Molding glass material

Abstract

[Problem] To provide a glass material that is to be used in molding and that has excellent stability when being reheated. [Solution] A glass material to be used in molding, wherein the maximum value αmax of the coefficient of linear expansion of the glass material and the total content [SiO2+ZrO2] of SiO2 and ZrO2 expressed as wt% satisfy formula (1). (1): αmax×[SiO2+ZrO2]≤27900

Description

[Technical Field]

[0001] The present invention relates to a glass material for molding. [Background technology]

[0002] Optical glass differs from conventional silicate-based glasses such as window glass and bottle glass in that it not only has specific optical constants such as refractive index and Abbe number, but also has high light transmittance and uniform optical properties.

[0003] In recent years, in order to keep up with the trend toward higher definition imaging equipment, there has been a growing demand for higher performance imaging equipment, as well as a growing demand for thinner optical elements themselves. This has led to a demand for optical glass that has a relatively high refractive index and excellent stability.

[0004] Examples of methods for manufacturing optical glass include the reheat press method, round bar molding method, extrusion molding method, etc., which involve reheating and shaping glass. In these manufacturing methods, silicate-based optical glass containing large amounts of components that improve optical properties, such as Nb2O5, TiO2, or La2O3, tends to have a problem in that the stability of the glass tends to decrease, and crystallization tends to progress particularly when reheated.

[0005] It is known that melts of inorganic compounds that easily crystallize can be vitrified by rapid cooling. Therefore, the inorganic glass of the present invention is obtained by cooling a molten inorganic compound at a rate faster than the rate at which crystallization proceeds, thereby maintaining or freezing the disordered atomic arrangement in the molten state even at room temperature.

[0006] However, optical glass that does not absorb at least visible light does not have a high thermal conductivity even in a molten state, so the cooling rate of the entire glass decreases as the thickness of the glass increases, and the rapid cooling effect is limited. For example, as shown in Non-Patent Document 1, if a 0.5 mm thick glass melt is press-molded with a metal plate, the cooling rate will be 10 2 ~10 3Even if a cooling rate of 100°C / sec can be obtained, when a 5 mm thick glass melt is press-molded with a metal plate, the cooling rate is only 10 to 20°C / sec. For this reason, the glass obtained by rapid cooling is said to be a "flake" as shown in Non-Patent Document 2.

[0007] Glass thick enough to be molded into optical elements is produced by continuously melting glass pieces approximately 10 mm thick, with some as thick as 30 or 40 mm. The presence of crystals inside the glass causes light scattering, making such glass unusable for optical elements. Even if glass of this thickness is obtained by rapidly cooling the surface, the interior of the glass may not be sufficiently cooled, resulting in the formation of crystals inside the glass. Furthermore, if the cooling conditions are too strong in an attempt to prevent such crystallization inside the glass, the surface of the glass will solidify before the interior, resulting in problems such as cracks or breakage of the glass.

[0008] Thus, when producing glass with a certain thickness, only the surface area can be vitrified without crystallization by the usual rapid cooling process. Furthermore, even if glass that has crystallized inside is reheated, the tendency to crystallize does not disappear, and there is a high possibility that the crystallization of the glass will progress again during molding. Therefore, the glass material obtained in this way cannot be softened by heating to obtain the desired shape, and therefore cannot be used as optical glass generally used in industry.

[0009] On the other hand, Patent Document 1 discloses prior art that proposes unusual cooling conditions for optical glass. Specifically, it discloses that for silicate glass containing a large amount of TiO2, a glass material can be obtained that can suppress the formation of crystals when reheated by cooling the molten glass to room temperature and then annealing it at a temperature lower than the glass transition temperature Tg to remove strain.

[0010] However, the optical glass obtained from the glass material of Patent Document 1 has low transmittance in the short wavelength region of visible light, especially blue light, and a large partial dispersion ratio Pg,F, and therefore cannot meet the demands of recent optical design. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-192384 [Non-patent literature]

[0012] [Non-Patent Document 1] Sakuka Tadao, "Science of Amorphous Glass" (1983) p.23 [Non-patent document 2] New Glass Forum, "Basic Lectures on New Glass" (1983), pp. 2-6 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above circumstances, and has as its object to provide a glass material for molding that has excellent stability when reheated. [Means for solving the problem]

[0014] The gist of the present invention is as follows. [1] Maximum linear expansion coefficient α max and the total content of SiO2 and ZrO2 in mass% [SiO2 + ZrO2] satisfy the following formula (1): α max ×[SiO2+ZrO2]≦27900 (1)

[0015] [2] Maximum value of linear expansion coefficient α max and the average linear expansion coefficient α at 100 to 300°C 100-300and the total content of SiO2 and ZrO2 [SiO2 + ZrO2] expressed in mass% satisfy the following formula (4): α max / α 100-300 ×[SiO2+ZrO2]≦264 (4)

[0016] [3] Maximum value of linear expansion coefficient α max The glass material for molding is soaked at the glass transition temperature Tg, then cooled at -30°C / hr for 4 hours, and then allowed to cool. The maximum linear expansion coefficient α of the glass material obtained is max (Tg) is smaller than that of a glass material for molding.

[0017] [4] The glass material for molding according to any one of [1] to [3], wherein when a sample of 11 mm × 11 mm × 10.5 mm is heat-treated for 5 minutes at a temperature 200°C higher than the glass transition temperature Tg, the number density D of crystals per 1 g of glass is less than 10 crystals / g.

[0018] [5] The glass material for molding according to any one of [1] to [4], wherein the TiO2 content [TiO2] and the Nb2O5 content [Nb2O5], expressed in mass%, satisfy the following formula (7): {5×[TiO2]} / {3×[Nb2O5]}≦3 (7)

[0019] [6] In the wavelength range of 280 to 700 nm, the wavelength λτ at which the internal transmittance of a 10 mm thick glass is 80% 80 The glass material for molding according to any one of [1] to [5], wherein the optical transmittance is 395 nm or less.

[0020] [7] The glass material for molding according to any one of [1] to [6], wherein the Abbe number vd and the partial dispersion ratio Pg,F satisfy the following formula (8): Pg,F≦-0.00286×νd+0.68700 (8)

[0021] [8] An optical glass made from the glass material for molding according to any one of [1] to [7] above. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a glass material for molding that has excellent stability when reheated. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a graph showing the glass temperature during the manufacturing process of an example of a glass material for molding according to this embodiment, where the vertical axis represents the glass temperature and the horizontal axis represents time (seconds) in logarithmic scale. DETAILED DESCRIPTION OF THE INVENTION

[0024] In this invention and this specification, glass compositions are expressed on an oxide basis unless otherwise specified. Here, "oxide-based glass composition" refers to a glass composition obtained by converting the glass raw materials into oxides that are present in the glass after they are all decomposed during melting, and each glass component is conventionally expressed as SiO2, TiO2, etc. The contents and total contents of glass components are expressed on a mass basis unless otherwise specified, and "%" means "mass %." Furthermore, "glass material for molding" may be simply referred to as "glass" or "glass material."

[0025] The content of glass components can be quantified by known methods, such as inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectroscopy (ICP-MS), etc. In this specification and the present invention, a content of 0% of a component means that the component is substantially not contained, and it is acceptable for the component to be contained at an unavoidable impurity level.

[0026] The glass material for molding of the present invention will be described below in three parts: a first embodiment, a second embodiment, and a third embodiment. The characteristics of the glass in the second and third embodiments are the same as those of the glass in the first embodiment. The actions and effects of each glass component in the second and third embodiments are the same as those of the glass component in the first embodiment. Therefore, in the second and third embodiments, matters that overlap with the explanation of the first embodiment will be omitted as appropriate.

[0027] First embodiment The glass material for molding according to the first embodiment is Maximum linear expansion coefficient α max and the total content of SiO2 and ZrO2 [SiO2 + ZrO2] expressed in mass % satisfy the following formula (1). α max ×[SiO2+ZrO2]≦27900 (1)

[0028] In the glass material for molding according to the first embodiment, the maximum value of the linear expansion coefficient α max and the total content of SiO2 and ZrO2 [SiO2 + ZrO2] expressed in mass % satisfy the following formula (1), preferably the following formula (2), and more preferably the following formula (3): By satisfying the following formula, a glass material for molding that has excellent stability when reheated can be obtained. α max ×[SiO2+ZrO2]≦27900 (1) α max ×[SiO2+ZrO2]≦27500 ···(2) α max ×[SiO2+ZrO2]≦27000 ···(3)

[0029] Maximum linear expansion coefficient α max can be controlled by adjusting the conditions for cooling the glass melt in the process of producing the glass material described below.

[0030] The linear expansion coefficient is measured in accordance with the Japan Engineering Society Standard JOGIS08. The sample is a round bar with a length of 20mm ± 0.5mm and a diameter of 5mm ± 0.5mm. With a load of 98mN applied to the sample, it is heated at a constant rate of 4°C per minute, and the temperature and expansion of the sample are measured every second. The maximum value of the linear expansion coefficient α max is the maximum value of the linear expansion coefficient between room temperature and the yield point temperature (the temperature at which the sample yields and the apparent expansion stops), so it is sufficient to find the linear expansion coefficient at the temperature at which the sample's expansion per unit temperature increase is at its maximum.MAX The maximum value obtained by performing a moving average process on the linear expansion coefficients at 31 measurement points may be used as the average linear expansion coefficient α 100-300 is the average value of the linear expansion coefficient at 100 to 300°C.

[0031] In this specification, the maximum value of the linear expansion coefficient α MAX and the average linear expansion coefficient α 100-300 In accordance with the provisions of JOGIS08, -7 °C -1 In other words, the maximum value of the linear expansion coefficient α MAX and the average linear expansion coefficient α 100-300 is [10 -7 °C -1 ] is displayed as an integer in units of . In this specification, the average linear expansion coefficient α is defined as [°C -1 ], but the unit is [K -1 ], the value of the average linear expansion coefficient α remains the same.

[0032] Non-limiting examples of properties and glass compositions other than those described above for the glass material for molding according to this embodiment are given below.

[0033] In the glass material for molding according to the first embodiment, the maximum value of the linear expansion coefficient α max and the average linear expansion coefficient α at 100 to 300°C 100-300 and the total content of SiO2 and ZrO2 [SiO2 + ZrO2] expressed in mass % preferably satisfy the following formula (4), more preferably satisfy the following formula (5), and even more preferably satisfy the following formula (5): In order to obtain a glass material for molding that has excellent stability when reheated, it is preferable that the following formula is satisfied. α max / α 100-300 ×[SiO2+ZrO2]≦264 (4) α max / α 100-300 ×[SiO2+ZrO2]≦260 (5) α max / α 100-300×[SiO2+ZrO2]≦255 (6)

[0034] Maximum linear expansion coefficient α max and the average linear expansion coefficient α 100-300 can be controlled by adjusting the conditions for cooling the glass melt in the process of producing the glass material described below.

[0035] In the glass material for molding according to the first embodiment, the maximum value of the linear expansion coefficient α max is preferably the maximum value α of the linear expansion coefficient of the glass material obtained by soaking the glass material for molding at the glass transition temperature Tg, then cooling it at -30°C / hr for 4 hours, and then allowing it to cool. max (Tg). However, the maximum linear expansion coefficient α max is the maximum value of the linear expansion coefficient α max (Tg) may be slightly larger than α max and α max (Tg) difference [α max (Tg)-α max ] is 10 -7 °C -1 When expressed in units of 1 to the first integer, it is preferably -9 or more, and more preferably -4 or more, 0 or more, 5 or more, 10 or more, 20 or more, 40 or more, 60 or more, 80 or more, 100 or more, 120 or more, 140 or more, 160 or more, 180 or more, 200 or more, 250 or more, 300 or more, 350 or more, and 400 or more in that order. max (Tg), and preferably α max (Tg) is about -100.

[0036] Maximum linear expansion coefficient α max (Tg) is the maximum value of the linear expansion coefficient of the glass obtained by holding the glass material for molding so that it is heated uniformly at the glass transition temperature Tg, and then cooling it at -30°C / hr for 4 hours. Note that the glass material for molding according to the first embodiment has a maximum linear expansion coefficient α max and the maximum value of the linear expansion coefficient α maxAs will be described later, the glass material for molding according to the first embodiment is obtained by being maintained at a temperature lower than the glass transition temperature Tg, and therefore does not have α max α smaller than (Tg) max It has.

[0037] When soaking at the glass transition temperature Tg, the glass material for molding may be heated to a temperature equal to or higher than Tg and then cooled to the same temperature as Tg, or the glass material for molding may be gradually heated to the same temperature as Tg.

[0038] 1 is a graph showing the glass temperature in the manufacturing process for an example of a molding glass material according to this embodiment. As will be described later, the molding glass material according to this embodiment is maintained at a temperature lower than the glass transition temperature Tg in step 2. Here, the maximum linear expansion coefficient α max (Tg) is the maximum value of the linear expansion coefficient for the glass obtained by maintaining the glass at the glass transition temperature Tg in step 2, as in the comparative example (Tg1) in FIG. 1. Alternatively, the maximum value of the linear expansion coefficient α max (Tg) may also be the maximum value of the linear expansion coefficient of the glass obtained by heating the glass material for molding from room temperature, soaking it at a temperature equal to Tg, and then cooling it, as in the comparative example (Tg2) in Figure 1.

[0039] When a molding glass material is heated to a temperature higher than the glass transition temperature Tg and then cooled, the lower limit of the time required for soaking at the glass transition temperature Tg depends on the size of the sample, but is approximately 30 minutes after the glass surface temperature reaches Tg, and may also be 1 hour, 2 hours, or 4 hours. There is no particular upper limit, and it is usually within 24 hours, preferably within 12 hours. The soaking time for the interior of the glass after reaching the Tg temperature may also be about 10 minutes.

[0040] When soaking a glass material for molding, even if the surface temperature of the glass reaches the glass transition temperature Tg, this does not necessarily mean that the internal temperature also reaches Tg. Whether soaking is sufficient can be determined by its specific gravity. Glass obtained by sufficiently soaking at the glass transition temperature Tg and then cooling shows almost no change in specific gravity even if the soaked state at Tg is maintained for a long time. On the other hand, glass obtained by cooling before soaking at the glass transition temperature Tg, for example, before the internal part of the glass reaches the glass transition temperature Tg, exhibits a difference in specific gravity compared to glass obtained by cooling after sufficiently soaking the internal part at Tg.

[0041] Therefore, for example, the absolute value of the change [d(t1)-d(t1+K)] between the specific gravity d(t1) of the glass obtained by heating a glass material for molding in a furnace so as to be soaked at the glass transition temperature Tg, holding the temperature for a holding time t1 (hr), and then cooling the glass and the specific gravity d(t1+K) of the glass obtained by heating the glass in a furnace, holding the temperature for a holding time t1+K (hr), and then cooling the glass is preferably 0.002 or less. Here, the lower limit of the value of K is preferably 4, more preferably 8, and even more preferably 12.

[0042] If the above change is satisfied, it can be determined that the heating for the holding time t1 is sufficient to soak the glass. In this case, the time required for soaking at the glass transition temperature Tg may be set to t1 or more.

[0043] The method for cooling the glass soaked at the glass transition temperature Tg is not particularly limited, as long as it is cooled at a cooling rate of −30° C. / hr for 4 hours after soaking. For example, a temperature-programmable slow cooling furnace can be used. If the temperature does not fall below the strain point of the glass even after cooling from the holding temperature Tg at a cooling rate of −30° C. / hr for 4 hours, the glass may be cooled from the holding temperature Tg at a cooling rate of −30° C. / hr for 5 to 6 hours.

[0044] The heating temperature during reheating is usually the temperature at which the glass softens and deforms. Specific examples of the heating temperature include a temperature about 50°C higher than the glass transition temperature Tg at the low end and a temperature about 200 to 300°C higher than the glass transition temperature Tg at the high end. When the heating temperature during reheating is low, i.e., when heating is performed at a temperature about 50°C higher than the glass transition temperature Tg, it is easy to ensure the stability of the glass, and the generation of crystals and devitrification can be suppressed.

[0045] However, if the reheating temperature is low, high pressure must be applied during molding. As a result, there is a higher possibility that cracks will occur in the molded glass product (e.g., lens, lens blank, round bar, extrusion molded product, etc.) or that the glass will break. Therefore, if the reheating temperature is low, the production yield is likely to decrease and the shapes of the glass molded products that can be molded are likely to be limited.

[0046] On the other hand, if the heating temperature during reheating is high, i.e., if heating is performed at a temperature about 200 to 300°C higher than the glass transition temperature Tg, deformation can be achieved in a shorter time and the degree of freedom in the shape of the molded product may be improved, but it is difficult to ensure the stability of the glass, and crystallization is likely to occur, leading to devitrification. For these reasons, in glasses having a composition such as that of the present invention, increasing the molding temperature makes crystals more likely to precipitate, and to avoid this crystal precipitation, it is necessary to lower the molding temperature than conventional glasses, which increases the possibility of deformation defects such as cracks and breakage.

[0047] In the glass material for molding according to the first embodiment, when a sample of 11 mm × 11 mm × 10.5 mm is heat-treated for 5 minutes at a temperature 200°C higher than the glass transition temperature Tg, the number density D of crystals per 1 g of glass is preferably less than 10 / g, with the upper limit being more preferably 9 / g, 8 / g, 7 / g, 6 / g, 5 / g, 4 / g, 3 / g, 2 / g, and 1 / g in that order. The number of crystals is most preferably 0 / g.

[0048] The number of crystals when calculating the number density D is the number of bright spots that can be recognized as crystals under an optical microscope (100x magnification).

[0049] The number density D is calculated by the following procedure.

[0050] [Sample preparation] First, observe with an optical microscope (100x magnification) to confirm that there are no visible foreign objects or crystals inside the glass. Then, cut and grind the glass to obtain a rectangular sample of approximately 11 mm x 11 mm x 10.5 mm. All surfaces of this sample are ground to a sand-polished surface using a grinding wheel with a grit size of #80 to #400.

[0051] [Heat treatment furnace temperature uniformity] The temperature is set to 200°C higher than the glass transition temperature Tg, and the material is heated in a heat treatment furnace with an internal space volume of approximately 25 cm x approximately 10 cm x approximately 10 cm that has been soaked for 15 minutes or more after the furnace temperature reaches Tg + 200°C.

[0052] In this case, the control thermometer of the heat treatment furnace is installed almost in the center of the internal space, and the glass sample is positioned within 3 cm of the control thermometer sensor when the glass sample is heat treated.

[0053] [Preheating the tray] The tray is a rectangular, hexahedral alumina ceramic plate measuring approximately 10.5 cm x 3 cm x 1 cm. An anti-fusing agent such as powdered alumina or a solid lubricant such as BN is applied to the tip of the tray in an amount of 0.01 to 0.3 g, preferably 0.5 g to 0.15 g, and more preferably 0.1 g. The glass sample is then placed on top of the tray and the tray is placed in a heat treatment furnace for heating. The tray is preheated in the heat treatment furnace for at least 15 minutes before testing.

[0054] [Heat treatment of glass samples] The saucer is removed from the heat treatment furnace just before the glass sample is introduced. The glass sample is immediately placed on the saucer in the position coated with the anti-fusing agent or solid lubricant, and the saucer and glass sample are returned to their original positions in the furnace. The time between removing the saucer and returning it to its original position is preferably within 10 seconds, more preferably within 8 seconds, and even more preferably within 6 seconds to avoid a drop in the temperature of the saucer. Five minutes after the glass sample is introduced, the glass and saucer are removed, and the glass sample is then removed from the saucer and cooled at a cooling rate sufficient to prevent breakage. To ensure efficient cooling without affecting the stability of the glass, the glass sample is removed from the furnace and immediately (approximately 3±1 seconds later) rolled onto a ceramic fiber or similar material, and then covered with ceramic fiber or similar material to prevent pressure on the top surface of the sample. After cooling, the edges of the glass sample are optically polished, and the interior of the glass sample is observed under an optical microscope (100x magnification). During optical polishing, preferably 80% or more, more preferably 85% or more of the softened glass sample is left as the observation volume. The number of crystals (bright spots) inside the glass sample is counted, and the weight of the sample after optical polishing is measured and converted into the number per gram.

[0055] In the glass material for molding according to the first embodiment, the TiO2 content [TiO2] and the Nb2O5 content [Nb2O5] expressed in mass % preferably satisfy the following formula (7). {5×[TiO2]} / {3×[Nb2O5]}≦3 (7)

[0056] The upper limit of the {5 × [TiO2]} / {3 × [Nb2O5]} ratio is preferably 2, with 1.25, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6, and 0.5 being more preferable in this order. On the other hand, from the viewpoint of particularly reducing Pg,F and further improving the transmittance λτ80 in the blue region, the upper limit of the {5 × [TiO2]} / {3 × [Nb2O5]} ratio is preferably 0.4, with 0.3, 0.2, and 0.1 being more preferable in this order. The {5 × [TiO2]} / {3 × [Nb2O5]} ratio can also be 0.0.

[0057] The above {5 × [TiO2]} / {3 × [Nb2O5]} represents the abundance ratio of Ti ions to Nb ions in the glass material for molding. If there are too many Ti ions, the partial dispersion ratio Pg,F may increase. Furthermore, there is a risk of fine crystal nuclei being generated when the molten glass is cooled, which may cause crystal growth under subsequent molding conditions, resulting in a decrease in optical quality and other problems that could interfere with glass production. Therefore, it is preferable to satisfy the above formula in order to suppress an increase in the partial dispersion ratio Pg,F and suppress glass crystallization.

[0058] In the glass material for molding according to the first embodiment, the partial dispersion ratio Pg,F preferably satisfies the following formula (8), more preferably the following formula (9), even more preferably the following formula (10), particularly preferably the following formula (11), and most preferably the following formula (12): When the partial dispersion ratio Pg,F satisfies the following formula, an optical glass that is suitable for correcting chromatic aberration can be provided. Pg,F≦-0.00286×νd+0.68700 (8) Pg,F≦-0.00286×νd+0.68600 (9) Pg,F≦-0.00286×νd+0.68500 (10) Pg,F≦-0.00286×νd+0.68400 (11) Pg,F≦-0.00286×νd+0.68300 (12)

[0059] The partial dispersion ratio Pg,F is expressed by the following formula (13) using the refractive indices ng, nF, and nC for the g-line, F-line, and C-line, respectively. Pg,F=(ng-nF) / (nF-nC) ···(13)

[0060] The partial dispersion ratio of Pg and F is the mass ratio [(Li2O + Na2O + K2O + Cs2O ) / (SiO2+P2O5+B2O3)], mass ratio [(Li2O+Na2O+K2O+Cs2O) / (Nb2O5+TiO2+WO3+Bi2O3)], mass ratio [(SiO2+P2O5+B2O3) / (Nb2O5+TiO2+WO3+Bi2O3)], mass ratio [ZrO2 / (Nb2O5+TiO2+WO3+Bi2O3)], mass ratio [P2O5 / (SiO2+P2O5+B2O3)], mass ratio [Nb2O5 / (Nb2O5+TiO2+WO3+Bi2O3)].

[0061] Also, ΔPg,F is the deviation of Pg,F from the normal line and is calculated as shown in equation (14). ΔPg,F=Pg,F-(0.6483-0.001802×νd) ···(14)

[0062] The molding glass material according to the first embodiment can be high-dispersion glass with a relatively small partial dispersion ratio Pg,f. By reducing the value of Pg,f in high-dispersion glass, it becomes easier to suppress the occurrence of focal length deviations near the g-line, i.e., chromatic aberration in the short wavelength range, when performing achromatization (adjusting the focal length) focusing on the usual F-line and C-line. It also makes it easier to improve the contrast when enlarging an image captured by a camera. Furthermore, when recognizing digital images electronically, it becomes easier to recognize the edges of the subject, which is expected to reduce the computational load on the image engine.

[0063] The glass material for molding according to this embodiment can have glass composition A, glass composition B, or glass composition C, which will be described in detail below.

[0064] (Glass composition A) The contents and ratios of the glass components and the glass properties when the glass material for molding according to this embodiment has glass composition A will be described below.

[0065] The glass material for molding according to this embodiment, in the case of glass composition A, is preferably a silicate glass containing SiO2 primarily as a glass network-forming component. The lower limit of the SiO2 content is preferably 0%, with larger values ​​being more preferred in the order of 6%, 11%, and 16%. In particular, when thermal stability is more important than the refractive index of the glass, the lower limit of the SiO2 content is preferably 21%, and can also be 24%, 26%, or 28%. The upper limit of the SiO2 content is preferably 40%, with smaller values ​​being more preferred in the order of 38%, 35%, and 33%. In particular, when refractive index is more important than glass stability, the upper limit of the SiO2 content is preferably 30%, and can also be 28%, 26%, or 25%.

[0066] In glass composition A, SiO2 serves as a glass network-forming component, improving the thermal stability, chemical durability, and weather resistance of the glass, increasing the viscosity of the glass melt, and making the glass melt easier to shape. It also increases the thermal stability during reheating and has the effect of reducing the crystal number density D. On the other hand, a high SiO2 content tends to reduce the devitrification resistance of the glass and increase Pg,F. Therefore, it is preferable that the SiO2 content be within the above range.

[0067] The glass material for molding according to this embodiment, when it has glass composition A, preferably contains P2O5. The lower limit of the P2O5 content is preferably 0%, and more preferably 0.2%, 0.4%, and 0.6%, in that order. The upper limit of the P2O5 content is preferably 10%, and more preferably 8%, 7%, 6%, 5%, and 4%, in that order.

[0068] In glass composition A, by satisfying the lower limit of the P2O5 content as described above, the thermal stability during reheating is improved and the number density D of the crystals is reduced. By satisfying the above upper limit, an increase in the partial dispersion ratio Pg,F can be suppressed, and stability during reheating can be maintained.

[0069] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the B2O3 content is preferably 20%, and more preferably 14%, 9%, and 4%, in that order. The B2O3 content may be 0%.

[0070] In glass composition A, B2O3 is a glass network-forming component that enhances the meltability of the glass and improves its thermal stability. On the other hand, if the B2O3 content is too high, there is a risk that the amount of volatilization of glass components increases during glass melting, and high dispersion is hindered, tending to reduce devitrification resistance. Furthermore, there is a risk that the viscosity of the glass will be lower than when the same amount of SiO2 is substituted. Furthermore, if excessive B2O3 is incorporated, there is a risk that the thermal stability during reheating will be reduced. Therefore, the B2O3 content is preferably within the above range.

[0071] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Al2O3 content is preferably 20%, and more preferably 9%, 4%, 2%, and 1% in that order. The lower limit of the Al2O3 content is preferably 0%, and more preferably 0.02%, 0.04%, 0.08%, 0.12%, 0.14%, 0.16%, 0.2%, and 0.3% in that order. The Al2O3 content may even be 0%.

[0072] In glass composition A, Al2O3 is a glass component that functions to improve the chemical durability and weather resistance of the glass, and can be considered a network-forming component. On the other hand, as the Al2O3 content increases, the devitrification resistance of the glass decreases. Furthermore, the glass transition temperature Tg increases, and problems such as a decrease in thermal stability when cooling the molten glass are likely to occur. To avoid such problems, the Al2O3 content is preferably within the above range. Furthermore, when a container and / or trough made of refractory bricks is used for melting or transporting the molten glass, the Al2O3 content can be set to 0.02% or more.

[0073] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the total content of SiO2 and P2O5 [SiO2 + P2O5] is preferably 5%, and more preferably 11%, 16%, and 21% in that order. In particular, when stability is important, the lower limit of the total content is preferably 24%, and can also be 27% or 30%. Furthermore, the upper limit of the total content is preferably 40%, and more preferably 38%, 36%, 34%, and 33% in that order.

[0074] In glass composition A, when the lower limit of the total content of SiO2 and P2O5 [SiO2 + P2O5] satisfies the above, thermal stability during reheating can be improved and the crystal number density D can be reduced. Furthermore, when the upper limit of the total content satisfies the above, a decrease in the refractive index and an increase in the partial dispersion ratio Pg,F can be suppressed, and the thermal stability of the glass can be maintained.

[0075] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the total content of SiO2, P2O5, and B2O3 [SiO2 + P2O5 + B2O3] is preferably 5%, and more preferably 10%, 15%, 18%, 21%, 22%, and 23% in that order. The upper limit of this total content is preferably 50%, and more preferably 45%, 40%, 37%, 35%, 34%, and 33% in that order. When refractive index is particularly important, the upper limit of this total content is preferably 30%, and can also be 28%, 26%, or 25%.

[0076] In glass composition A, the total content [SiO2+P2O5+B2O3] is preferably within the above range, from the viewpoint of maintaining stability during reheating.

[0077] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the B2O3 content to the SiO2 content [B2O3 / SiO2] is preferably 0.8 The lower limit of the mass ratio is preferably 0, and more preferably 0.70, 0.60, 0.50, 0.40, 0.30, 0.20, 0.10, 0.05, and 0.03 in that order. The lower limit of the mass ratio is preferably 0, and more preferably 0.005, 0.01, 0.015, and 0.02 in that order. The mass ratio may even be 0.

[0078] In glass composition A, the mass ratio [B2O3 / SiO2] is preferably within the above range, from the viewpoint of suppressing an increase in the specific gravity of the glass and suppressing an increase in coloration of the glass.

[0079] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the mass ratio of the content of P2O5 to the total content of SiO2 and P2O5 [P2O5 / (SiO2+P2O5)] is preferably 0.00, and more preferably 0.006, 0.011, 0.016, and 0.021 in that order. The upper limit of this mass ratio is preferably 0.20, and more preferably 0.18, 0.16, 0.14, 0.12, and 0.11 in that order.

[0080] In glass composition A, if the mass ratio [P2O5 / (SiO2+P2O5)] is too low, stability during reheating may deteriorate, while if it is too high, the partial dispersion ratio Pg,F may increase. Therefore, it is preferable that the mass ratio is within the above range.

[0081] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the mass ratio of the content of P2O5 to the total content of SiO2, P2O5, and B2O3 [P2O5 / (SiO2+P2O5+B2O3)] is preferably 0.00, and more preferably 0.006, 0.011, 0.016, and 0.021 in that order. The upper limit of this mass ratio is preferably 0.20, and more preferably 0.18, 0.16, 0.14, 0.12, and 0.11 in that order.

[0082] In the glass composition A, if the mass ratio [P2O5 / (SiO2+P2O5+B2O3)] is too high, the partial dispersion ratio Pg,F may increase. Therefore, it is preferable that the mass ratio is within the above range.

[0083] In the glass material for molding according to this embodiment, for glass composition A, the mass ratio of the SiO content to the total content of SiO, P, and B is preferably 0.100, and more preferably 0.200, 0.300, 0.400, 0.500, 0.600, 0.700, 0.800, 0.820, 0.840, and 0.860. The upper limit of this mass ratio is preferably 1.000, and more preferably 0.995, 0.990, 0.985, 0.980, and 0.978, in that order.

[0084] In glass composition A, the mass ratio [SiO2 / (SiO2+P2O5+B2O3)] is preferably within the above range, from the viewpoint of maintaining stability during reheating.

[0085] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the ZrO2 content is preferably 0%, and more preferably 2%, 3%, 4%, and 5%, in that order. In particular, when stability is more important than refractive index, the lower limit of the ZrO2 content is preferably 6%, or can be 8%. Furthermore, the upper limit of the ZrO2 content is preferably 15%, and more preferably 14%, 13%, 12%, 11%, and 10%, in that order. In particular, when the refractive index is more important than stability, the upper limit of the ZrO2 content is preferably 9%, and can also be set to 8%, 7%, or 6%.

[0086] In glass composition A, when the lower limit of the ZrO2 content satisfies the above, high refractive index, high dispersion, and high internal transmittance λτ 80Furthermore, by ensuring that the upper limit of the ZrO2 content satisfies the above-mentioned range, an increase in the partial dispersion ratio Pg,F can be suppressed, the occurrence of defects in optical elements can be suppressed, and the meltability and thermal stability of the glass can be maintained.

[0087] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the Nb2O5 content is preferably 1%, and more preferably 11%, 21%, 26%, 31%, 34%, and 36% in that order. When the refractive index is particularly important over stability, the lower limit of the Nb2O5 content is preferably 39%, and can also be 41%, 46%, 49%, or 50%. Furthermore, the upper limit of the Nb2O5 content is preferably 80%, and more preferably 70%, 64%, 59%, 56%, and 54% in that order. When the stability is particularly important over refractive index, the upper limit of the Nb2O5 content is preferably 51%, and can also be 47%, 44%, 43%, or 38%.

[0088] In glass composition A, if the lower limit of the Nb2O5 content satisfies the above, a high refractive index, high dispersion glass with a reduced partial dispersion ratio Pg,F can be obtained. Nb2O5 is also a glass component that improves the thermal stability and chemical durability of the glass. If the content is low, Pg,F may increase, while if it is excessive, the thermal stability of the glass may deteriorate. Therefore, if the upper limit of the Nb2O5 content satisfies the above, the thermal stability and chemical durability of the glass can be maintained well and the formability during reheating can be improved.

[0089] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the TiO content is preferably 0%, and more preferably 1%, 2%, 3%, and 4% in that order. The upper limit of the TiO content is preferably 20%, and more preferably 15%, 11%, 8%, and 6% in that order.

[0090] TiO2 is a component that contributes to a high refractive index and high dispersion in glass composition A. When coexisting with Nb2O5, it improves glass stability while maintaining a high refractive index, improving stability during reheating. However, excessive TiO2 content can increase the partial dispersion ratio Pg,F and reduce the transmittance of the glass in the short wavelength range. Furthermore, crystals can form in a temperature range lower than the glass's deformation point, potentially hindering glass productivity. Therefore, the TiO2 content is preferably within the above range.

[0091] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the total content of Nb2O5 and TiO2 [Nb2O5 + TiO2] is preferably 10%, and more preferably 20%, 30%, 35%, 38%, 39%, 40%, and 41% in this order. When the refractive index is particularly important over stability, the lower limit of the total content is preferably 45%, and can also be 48%, 51%, 53%, or 55%. Furthermore, the upper limit of the total content is preferably 80%, and more preferably 75%, 70%, 65%, 62%, 59%, and 56% in this order. When the stability is particularly important over refractive index, the upper limit of the total content is preferably 53%, and can also be 50%, 47%, 44%, or 43%.

[0092] In glass composition A, from the viewpoint of improving glass stability while maintaining a high refractive index and improving stability during reheating, the total content [Nb2O5+TiO2] is preferably within the above range.

[0093] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the TiO2 content to the Nb2O5 content [TiO2 / Nb2O5] is preferably 0.50, and more preferably 0.40, 0.30, 0.20, 0.18, and 0.16 in that order. The lower limit of this mass ratio is preferably 0, and more preferably 0.02, 0.04, 0.06, 0.08, and 0.10 in that order. This mass ratio may even be 0.

[0094] In glass composition A, from the viewpoint of suppressing an increase in the partial dispersion ratio Pg,F and increasing λτ80, the mass ratio [TiO2 / Nb2O5] is preferably in the above range.

[0095] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the mass ratio of the P2O5 content to the Nb2O5 content [P2O5 / Nb2O5] is preferably 0.000, and more preferably 0.005, 0.010, 0.015, and 0.020 in that order. The upper limit of this mass ratio is preferably 0.200, and more preferably 0.150, 0.100, 0.090, and 0.080 in that order.

[0096] In the glass composition A, from the viewpoint of suppressing an increase in the partial dispersion ratio Pg,F, the mass ratio [P2O5 / Nb2O5] is preferably in the above range.

[0097] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the mass ratio of the content of P2O5 to the total content of Nb2O5 and TiO2 [P2O5 / (Nb2O5+TiO2)] is preferably 0.000, and more preferably 0.005, 0.010, 0.015, and 0.018 in that order. The upper limit of this mass ratio is preferably 0.200, and more preferably 0.150, 0.100, 0.090, and 0.080 in that order.

[0098] In glass composition A, from the viewpoint of obtaining the desired high dispersibility, the mass ratio [P2O5 / (Nb2O5+TiO2)] is preferably in the above range.

[0099] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the WO3 content is preferably 20%, and more preferably 17%, 14%, 11%, 8%, 6%, 4%, 3%, 2%, 1%, 0.5%, and 0.2%, in that order. The lower limit of the WO3 content is preferably 0%. The WO3 content may be 0%.

[0100] WO3 is a component that improves the stability of glass composition A during reheating. On the other hand, WO3 increases the partial dispersion ratio Pg,F. It also tends to cause coloration of the glass and reduces λτ80. Therefore, the WO3 content is preferably within the above range.

[0101] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Bi2O3 content is preferably 20%, and more preferably 17%, 14%, 11%, 8%, 6%, 4%, 3%, 2%, 1%, 0.5%, and 0.2%, in that order. The lower limit of the Bi2O3 content is preferably 0%. The Bi2O3 content may be 0%.

[0102] When an appropriate amount of Bi2O3 is contained in glass composition A, it serves to improve the thermal stability of the glass. On the other hand, if the Bi2O3 content is too high, the partial dispersion ratio Pg,F increases. Furthermore, there is a risk that the coloring of the glass increases and λτ80 decreases. Therefore, it is preferable that the Bi2O3 content be within the above range.

[0103] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the total content of Nb2O5, TiO2, WO3, and Bi2O3 [Nb2O5 + TiO2 + WO3 + Bi2O3] is preferably 80%, and more preferably 75%, 70%, 65%, 62%, 59%, and 56% in that order. When stability is particularly important over refractive index, the upper limit of the total content is preferably 53%, and can also be 50%, 47%, 44%, or 43%. Furthermore, the lower limit of the total content is preferably 10%, and more preferably 20%, 30%, 35%, 38%, 39%, 40%, and 41% in that order. When refractive index is particularly important over stability, the lower limit of the total content is preferably 45%, and can also be 48%, 51%, 53%, or 55%.

[0104] In glass composition A, TiO2, WO3, and Bi2O3, together with Nb2O5, are components that contribute to a high refractive index and high dispersion. Therefore, the total content [Nb2O5 + TiO2 + WO3 + Bi2O3] is preferably within the above range.

[0105] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the content of Nb2O5 to the total content of Nb2O5, TiO2, WO3, and Bi2O3 [Nb2O5 / (Nb2O5+TiO2+WO3+Bi2O3)] is preferably 1, and more preferably 0.98, 0.96, 0.94, and 0.92, in order from the viewpoints of maintaining the thermal stability of the glass, increasing the λτ80 of the glass, and improving stability during reheating. The lower limit of this mass ratio is preferably 0.1, and more preferably 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8, in order.

[0106] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the content of ZrO2 to the total content of Nb2O5, TiO2, WO3, and Bi2O3 [ZrO2 / (Nb2O5+TiO2+WO3+Bi2O3)] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, and 0.25, from the viewpoint of maintaining the thermal stability of the glass. Moreover, the lower limit of the mass ratio [ZrO2 / (Nb2O5+TiO2+WO3+Bi2O3)] is preferably 0.01, and more preferably 0.03, 0.05, 0.08, 0.09, 0.10, and 0.11, from the viewpoint of increasing the λτ80 of the glass. From the viewpoint of maintaining high dispersibility of the glass, the upper limit of the mass ratio [ZrO2 / (Nb2O5+TiO2+WO3+Bi2O3)] can also be set to 0.02, 0.01, or 0.00.

[0107] In the glass according to this embodiment, for glass composition A, the upper limit of the mass ratio of the total content of SiO, P, and B to the total content of Nb, Ti, W, and Bi, [(SiO + P + B) / (Nb + Ti, W, and Bi)] is preferably 5, and more preferably 4, 3, 2, 1.5, 1.3, 1.1, 1.0, 0.9, and 0.8, in that order. When refractive index is particularly important, the upper limit of this mass ratio is preferably 0.7, and can also be 0.6, 0.5, or 0.45. The lower limit of this mass ratio is preferably 0.013, and more preferably 0.10, 0.20, 0.30, 0.35, and 0.40, in that order. When stability is particularly important, the lower limit of the mass ratio is preferably 0.50, and can also be set to 0.60, 0.70, or 0.75.

[0108] In glass composition A, by setting the mass ratio [(SiO2+P2O5+B2O3) / (Nb2O5+TiO2+WO3+Bi2O3)] within the above range, the refractive index of the glass can be adjusted and thermal stability can be maintained.

[0109] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Ta2O5 content is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4%, 2%, and 1% in that order. The lower limit of the Ta2O5 content is preferably 0%. The Ta2O5 content may be 0%.

[0110] Ta2O5 is a glass component in glass composition A that functions to improve the thermal stability of the glass. On the other hand, if the Ta2O5 content is high, the thermal stability of the glass decreases, and when the glass is melted, unmelted glass raw materials are likely to remain. In addition, Ta2O5 is an expensive component, and there is a risk that the manufacturing cost of the glass will increase. Therefore, the Ta2O5 content is preferably within the above range.

[0111] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the Ta2O5 content to the total content of Ta2O5, Nb2O5, TiO2, WO3, and Bi2O3 [Ta2O5 / (Ta2O5+Nb2O5+TiO2+WO3+Bi2O3)] is preferably 0.9, and more preferably 0.7, 0.5, 0.3, 0.2, 0.1, and 0.05 in that order. The lower limit of this mass ratio is preferably 0.000.

[0112] In glass composition A, the mass ratio [Ta2O5 / (Ta2O5+Nb2O5+TiO2+WO3+Bi2O3)] is preferably within the above range, from the viewpoint of suppressing an increase in specific gravity and suppressing an increase in the manufacturing cost of the glass.

[0113] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the LiO content is preferably 10%, and more preferably 9%, 8%, 7%, and 6% in that order. The lower limit of the LiO content is preferably 0%, and more preferably 1%, 2%, 3%, 3.5%, 4%, and 4.5% in that order.

[0114] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Na2O content is preferably 30%, and more preferably 25%, 20%, 18%, 16%, 14, and 12% in that order. The lower limit of the Na2O content is preferably 0%, and more preferably 1%, 2%, 3%, 3.5%, 4%, 4.5%, and 5% in that order.

[0115] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the K2O content is preferably 30%, and more preferably 20%, 15%, 10%, 7%, and 4% in that order. The lower limit of the K2O content is preferably 0%, and more preferably 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% in that order.

[0116] In glass composition A, Li2O, Na2O, and K2O all function to lower the liquidus temperature and improve the thermal stability of the glass, but if their contents increase, the chemical durability and weather resistance decrease. Therefore, it is preferable that the contents of Li2O, Na2O, and K2O are each within the above-mentioned ranges.

[0117] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the total content of LiO, NaO, and KO [LiO + NaO + KO] is preferably 1%, and more preferably 5%, 8%, 10%, 12%, 13%, and 14% in that order. The upper limit of the total content is preferably 40%, and more preferably 35%, 30%, 25%, 22%, 20%, 19%, 18%, and 17% in that order.

[0118] In glass composition A, when the lower limit of the total content [Li2O + Na2O + KO] satisfies the above range, the meltability of the glass can be improved and an increase in the liquidus temperature can be suppressed. When the upper limit of the total content satisfies the above range, the viscosity of the glass can be increased, the crystallization rate of the glass melt can be reduced, and stability during reheating can be improved.

[0119] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the mass ratio of the total content of Li2O, Na2O, and K2O to the total content of Nb2O5 and TiO2 [(Li2O + Na2O + K2O) / (Nb2O5 + TiO2)] is preferably 0.10, and more preferably 0.15, 0.18, 0.21, 0.23, and 0.25 in that order. The upper limit of this mass ratio is preferably 0.70, and more preferably 0.65, 0.60, 0.55, 0.50, and 0.45 in that order.

[0120] In glass composition A, the mass ratio [(Li2O+Na2O+K2O) / (Nb2O5+TiO2)] is preferably in the above range, from the viewpoint of obtaining desired optical constants while maintaining the melting characteristics and thermal stability of the glass.

[0121] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the content of P2O5 to the total content of Li2O, Na2O, K2O, and Nb2O5 [P2O5 / (Li2O+Na2O+K2O+Nb2O5)] is preferably 0.500, and more preferably 0.400, 0.300, 0.200, 0.100, 0.080, 0.070, and 0.060 in that order. The lower limit of this mass ratio is preferably 0, and more preferably 0.005, 0.010, 0.011, 0.012, 0.013, and 0.014 in that order.

[0122] In glass composition A, from the viewpoint of stabilizing the glass and suppressing an increase in the partial dispersion ratio Pg,F, the mass ratio [P2O5 / (Li2O+Na2O+K2O+Nb2O5)] is preferably in the above range.

[0123] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the CsO content is preferably 10%, and more preferably 8%, 6%, 4%, 3%, 2%, and 1% in that order. The lower limit of the CsO content is preferably 0%.

[0124] In glass composition A, CsO functions to improve the thermal stability of the glass, but if its content increases, the chemical durability and weather resistance decrease. Therefore, the CsO content is preferably within the above range.

[0125] In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the total content of LiO, NaO, KO, and CsO [LiO + NaO + KO + CsO] is preferably 1%, and more preferably 5%, 8%, 10%, 12%, 13%, and 14% in that order. The upper limit of the total content is preferably 40%, and more preferably 35%, 30%, 25%, 22%, 20%, 19%, 18%, and 17% in that order.

[0126] In glass composition A, the total content [Li2O+Na2O+K2O+Cs2O] is preferably within the above range, from the viewpoint of maintaining stability during reheating.

[0127] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the LiO content to the total content of LiO, NaO, KO, and CsO [LiO / (LiO+NaO+KO+CsO)] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.45, and 0.4, in order from the viewpoint of suppressing an increase in the liquidus temperature and suppressing a decrease in weather resistance. The lower limit of this mass ratio is preferably 0, and more preferably 0.1, 0.2, 0.25, 0.29, 0.31, and 0.33, in order.

[0128] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the content of Na2O to the total content of Li2O, Na2O, K2O, and Cs2O [Na2O / (Li2O+Na2O+K2O+Cs2O)] is preferably 1, and more preferably 0.95, 0.9, 0.85, 0.80, 0.75, 0.70, and 0.66, in order from the viewpoint of suppressing an increase in the liquidus temperature and suppressing a decrease in weather resistance. The lower limit of this mass ratio is preferably 0, and more preferably 0.1, 0.2, 0.25, 0.29, 0.31, 0.33, and 0.34, in order.

[0129] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the content of K2O to the total content of Li2O, Na2O, K2O, and Cs2O [K2O / (Li2O+Na2O+K2O+Cs2O)] is preferably 1, and more preferably 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.28, and 0.27, in order from the viewpoint of suppressing an increase in the liquidus temperature and suppressing a decrease in weather resistance. The lower limit of this mass ratio is preferably 0, and more preferably 0.1, 0.15, 0.20, 0.22, 0.24, and 0.25, in order.

[0130] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the content of P2O5 to the total content of Li2O, Na2O, K2O, Cs2O, Nb2O5, TiO2, WO3, and Bi2O3 [P2O5 / (Li2O+Na2O+K2O+Cs2O+Nb2O5+TiO2+WO3+Bi2O3)] is preferably 1, and more preferably 0.5, 0.3, 0.1, 0.08, 0.07, and 0.06 in that order. The lower limit of this mass ratio is preferably 0, and more preferably 0.005, 0.008, 0.011, and 0.012 in that order.

[0131] In glass composition A, the desired Abbe number νd and partial dispersion ratio Pg,F can be obtained by appropriately incorporating Li2O, Na2O, K2O, Cs2O, Nb2O5, TiO2, WO3, and Bi2O3 as glass components. However, incorporating these components into silicate-based glass may reduce stability during reheating. On the other hand, P2O5 is a component that improves stability during reheating. Therefore, if the mass ratio [P2O5 / (Li2O + Na2O + K2O + Cs2O + Nb2O5 + TiO2 + WO3 + Bi2O3)] is too high, the stability of the glass may be reduced and the partial dispersion ratio Pg,F may increase. Conversely, if it is too low, the stability during reheating may be reduced. Therefore, it is preferable that the mass ratio be within the above range.

[0132] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the total content of Li2O, Na2O, K2O, and Cs2O to the total content of SiO2, P2O5, and B2O3 [(Li2O + Na2O + K2O + Cs2O) / (SiO2 + P2O5 + B2O3)] is preferably 5, and more preferably 4, 3, 2, 1.5, 1, 0.9, 0.8, 0.7, and 0.6, in that order. The lower limit of this mass ratio is preferably 0.02, and more preferably 0.1, 0.2, 0.3, 0.4, and 0.45, in that order.

[0133] In glass composition A, if the mass ratio [(Li2O + Na2O + K2O + Cs2O) / (SiO2 + P2O5 + B2O3)] is too low, the glass transition temperature Tg increases, the meltability deteriorates, and the partial dispersion ratio Pg,F may increase. On the other hand, if it is too high, the viscosity of the glass during melting decreases, the thermal stability of the melt decreases, and the stability during reheating may deteriorate.

[0134] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the total content of Li2O, Na2O, K2O, and Cs2O to the total content of Nb2O5, TiO2, WO3, and Bi2O3 [(Li2O + Na2O + K2O + Cs2O) / (Nb2O5 + TiO2 + WO3 + Bi2O3)] is preferably 4, and more preferably 3, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, and 0.5, in that order. The lower limit of this mass ratio is preferably 0.015, and more preferably 0.100, 0.200, and 0.300, in that order.

[0135] In glass composition A, if the mass ratio [(Li2O + Na2O + K2O + Cs2O) / (Nb2O5 + TiO2 + WO3 + Bi2O3)] is too low, the partial dispersion ratio Pg,F increases and the transmittance may deteriorate. On the other hand, if it is too high, the Abbe number increases, the refractive index decreases, and the stability during reheating may deteriorate.

[0136] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the MgO content is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1%, in that order. The upper limit may be 0%. The lower limit of the MgO content is preferably 0%. In particular, when increasing the resistivity of the glass to improve melting efficiency, the lower limit of the MgO content is preferably 1%, and can also be 2%, 4%, or 6%.

[0137] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the CaO content is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1%, in that order. The upper limit may be 0%. The lower limit of the CaO content is preferably 0%. In particular, when increasing the resistivity of the glass to improve melting efficiency, the lower limit of the CaO content is preferably 1%, and can also be 2%, 4%, 6%, or 8%.

[0138] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the SrO content is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1%, in that order. The upper limit may be 0%. The lower limit of the SrO content is preferably 0%. In particular, when increasing the resistivity of the glass to improve melting efficiency, the lower limit of the SrO content is preferably 1%, and can also be 2%, 4%, 6%, or 8%.

[0139] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the BaO content is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1%, in that order. The upper limit may be 0%. The lower limit of the BaO content is preferably 0%. In particular, when increasing the resistivity of the glass to improve melting efficiency, the lower limit of the BaO content is preferably 1%, and can also be 2%, 4%, 6%, or 8%.

[0140] In glass composition A, MgO, CaO, SrO, and BaO are glass components that improve the thermal stability and devitrification resistance of the glass. However, if the content of these glass components increases, the specific gravity increases, high dispersibility is impaired, and the thermal stability and devitrification resistance of the glass decrease. Therefore, it is preferable that the content of each of these glass components be within the above-mentioned range.

[0141] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the ZnO content is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1%, in that order. The upper limit may be 0%. The lower limit of the ZnO content is preferably 0%. In particular, when increasing the resistivity of the glass to improve melting efficiency or when lowering the glass transition point, the lower limit of the ZnO content is preferably 1%, and can also be 2%, 4%, or 6%.

[0142] ZnO is a glass component in glass composition A that functions to improve the thermal stability of the glass. However, if the ZnO content is too high, the specific gravity may increase. Therefore, the ZnO content is preferably within the above range.

[0143] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the total content of MgO and CaO [MgO + CaO] is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1% in that order. The upper limit may be 0%. The lower limit of the total content is preferably 0%. From the viewpoint of maintaining thermal stability without interfering with high dispersion, the total content is preferably within the above range.

[0144] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the total content of MgO, CaO, SrO, BaO, and ZnO [MgO + CaO + SrO + BaO + ZnO] is preferably 20%, and more preferably 14%, 9%, 4%, 2%, and 1%, in that order. The upper limit may be 0%. The lower limit of the total content is preferably 0%. In particular, when increasing the resistivity of the glass to improve melting efficiency, the lower limit of the total content is preferably 1%, and can also be 2%, 4%, 6%, or 8%. From the viewpoints of suppressing an increase in specific gravity and maintaining thermal stability without hindering high dispersion, the total content is preferably within the above range.

[0145] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of LiO, NaO, KO, and CsO [(MgO + CaO + SrO + BaO + ZnO) / (LiO + NaO + KO + CsO)] is preferably 20, and more preferably 18, 16, and 14 in that order. The lower limit of this mass ratio is preferably 0, and more preferably 5, 8, 10, 12, and 13 in that order. This mass ratio may even be 0. From the viewpoints of suppressing an increase in the specific gravity of the glass, improving the filling rate of the glass to achieve a high refractive index and high dispersion while enhancing meltability, and maintaining an appropriate resistivity of the glass, it is preferable that this mass ratio be within the above range.

[0146] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the La2O3 content is preferably 20%, and more preferably 17%, 14%, and 12%, in that order. When stability is more important than refractive index, the upper limit of the La2O3 content can be 9%, 7%, 5%, 3%, 2%, or 1%. The upper limit may be 0%. Furthermore, the lower limit of the La2O3 content is preferably 0%. In particular, when the refractive index is increased while maintaining the content of the glass-forming components, the lower limit of the La2O3 content is preferably 1%, and can also be 2%, 4%, or 6%.

[0147] In glass composition A, if the content of La2O3 is too high, the high dispersion of the glass is suppressed and the thermal stability is reduced. Therefore, it is preferable that the content of La2O3 is within the above range.

[0148] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Y2O3 content is preferably 20%, and more preferably 17%, 14%, and 12%, in that order. When stability is more important than refractive index, the upper limit of the Y2O3 content can be 9%, 7%, 5%, 3%, 2%, or 1%. The upper limit may be 0%. Furthermore, the lower limit of the Y2O3 content is preferably 0%. In particular, when the refractive index is increased while maintaining the content of the glass-forming components, the lower limit of the Y2O3 content is preferably 1%, and can also be 2%, 3%, or 5%.

[0149] In glass composition A, if the Y2O3 content is too high, the high dispersion of the glass is suppressed, the thermal stability is reduced, and the glass is prone to devitrification during production. Therefore, the Y2O3 content is preferably within the above range.

[0150] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Sc2O3 content is preferably 3%, and more preferably 2%, 1.5%, 1%, and 0.5%, in that order. The upper limit may be 0%. The lower limit of the Sc2O3 content is preferably 0%.

[0151] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the HfO2 content is preferably 3%, and more preferably 2%, 1.5%, 1%, and 0.5%, in that order. The upper limit may be 0%. The lower limit of the HfO2 content is preferably 0%.

[0152] Sc2O3 and HfO2 have the function of increasing the dispersibility of the glass in glass composition A, but are expensive components, so the contents of Sc2O3 and HfO2 are preferably within the above ranges.

[0153] Note that a certain amount of HfO2 may be contained in the raw material for ZrO2. Therefore, glass containing ZrO2 may contain a certain amount of HfO2. Therefore, in the glass material for molding according to the first embodiment, in the case of glass composition A, the mass ratio of the HfO2 content to the ZrO2 content [HfO2 / ZrO2] may also be within a predetermined range. For example, the lower limit of the mass ratio [HfO2 / ZrO2] may be 0.005, or even 0.010, 0.013, or 0.015. On the other hand, the upper limit of the mass ratio may be 0.05, or even 0.040, 0.030, 0.020, or 0.018. From the viewpoint of preventing components of the refractory brick from dissolving into the glass, it is preferable that the glass contain a small amount of ZrO2, and therefore the HfO2 content is preferably within the above range.

[0154] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Lu2O3 content is preferably 3%, and more preferably 2%, 1.5%, 1%, and 0.5%, in that order. The upper limit may be 0%. The lower limit of the Lu2O3 content is preferably 0%.

[0155] In glass composition A, Lu2O3 has the function of increasing the dispersibility of the glass, but because of its large molecular weight, it is also a glass component that increases the specific gravity of the glass. Therefore, the content of Lu2O3 is preferably within the above range.

[0156] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the GeO2 content is preferably 3%, and more preferably 2%, 1.5%, 1%, and 0.5%, in that order. The upper limit may be 0%. The lower limit of the GeO2 content is preferably 0%.

[0157] In glass composition A, GeO2 has the function of increasing the high dispersibility of the glass, but is an extremely expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of the glass, it is preferable that the content of GeO2 be in the above range.

[0158] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Gd2O3 content is preferably 3%, and more preferably 2%, 1.5%, 1%, and 0.5%, in that order. The upper limit may be 0%. The lower limit of the Gd2O3 content is preferably 0%.

[0159] In glass composition A, if the Gd2O3 content is too high, the thermal stability of the glass decreases. Furthermore, if the Gd2O3 content is too high, the specific gravity of the glass increases, which is undesirable. Therefore, from the viewpoint of suppressing an increase in specific gravity while maintaining good thermal stability of the glass, it is preferable that the Gd2O3 content be within the above range.

[0160] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Yb2O3 content is preferably 3%, and more preferably 2%, 1.5%, 1%, and 0.5%, in that order. The upper limit may be 0%. The lower limit of the Yb2O3 content is preferably 0%.

[0161] In glass composition A, Yb2O3 has a larger molecular weight than La2O3, Gd2O3, and Y2O3, and therefore increases the specific gravity of the glass. An increase in the specific gravity of the glass increases the mass of the optical element. For example, if a heavy lens is incorporated into an autofocus imaging lens, the power required to drive the lens during autofocusing increases, resulting in rapid battery consumption. Therefore, it is desirable to reduce the Yb2O3 content and suppress the increase in the specific gravity of the glass.

[0162] Furthermore, if the Yb2O3 content in glass composition A is too high, the thermal stability of the glass decreases and absorption in the near-infrared region is likely to occur. From the viewpoints of maintaining the transmittance of the glass in the near-infrared region, preventing a decrease in thermal stability, and suppressing an increase in specific gravity, the Yb2O3 content is preferably within the above range.

[0163] In the case of glass composition A, the glass material for molding according to this embodiment is preferably composed mainly of the above-mentioned glass components, namely, SiO2, P2O5, B2O3, Al2O3, ZrO2, TiO2, Nb2O5, WO3, Bi2O3, Ta2O5, Li2O, Na2O, K2O, Cs2O, MgO, CaO, SrO, BaO, ZnO, La2O3, Y2O3, Sc2O3, HfO2, Lu2O3, GeO2, Gd2O3, and Yb2O3, and the lower limit of the total content of the above-mentioned glass components is preferably 95.5%, and more preferably 96.0%, 96.5%, 97.0%, 97.5%, 98.0%, 98.5%, and 99.0%, in that order.

[0164] It is preferable that the glass material for molding according to this embodiment is basically composed of the above glass components, but it may contain other components as long as they do not impair the effects of the present invention. Furthermore, the present invention does not exclude the inclusion of unavoidable impurities.

[0165] (Other ingredients) Pb, As, Cd, Tl, Be, and Se are all toxic, and therefore the glass material for molding according to this embodiment preferably does not contain these elements as glass components.

[0166] U, Th, and Ra are all radioactive elements, and therefore the glass material for molding according to this embodiment preferably does not contain these elements as glass components.

[0167] V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, and Tm increase the coloration of the glass and can be sources of fluorescence, so it is preferable that the glass material for molding according to this embodiment does not contain these elements as glass components.

[0168] Sb (Sb2O3) and Ce (CeO2) are elements that can be added as optional fining agents. Of these, Sb (Sb2O3) is a fining agent with a large fining effect, and even when introduced in small amounts, it promotes the oxidation of easily reduced components and increases λτ80. Ce (CeO2) has a smaller fining effect than Sb (Sb2O3). Ce (CeO2) tends to intensify the coloring of glass when added in large amounts.

[0169] The Sb2O3 content is expressed as an exclusive ratio. That is, when the total content of all glass components other than Sb2O3 and CeO2 is 100 mass%, the upper limit of the Sb2O3 content is preferably 1.000 mass%, and more preferably 0.500 mass%, 0.300 mass%, 0.100 mass%, 0.080 mass%, 0.060 mass%, and 0.040 mass% in that order. The lower limit of the Sb2O3 content is preferably 0.000 mass%, and more preferably 0.001 mass%, 0.003 mass%, 0.005 mass%, 0.010 mass%, 0.015 mass%, and 0.020 mass% in that order. Since Sb2O3 itself shifts the transmission / absorption edge of the glass to longer wavelengths, from the viewpoint of increasing the transmittance of the glass in the short wavelength range as much as possible, the Sb2O3 content may be 0.008 mass% or less, or even 0.004 mass% or less, or even 0.000 mass%.

[0170] The CeO2 content is also expressed as an exclusive percentage. That is, when the total content of all glass components other than CeO2 and Sb2O3 is taken as 100 mass%, the upper limit of the CeO2 content is preferably 1.000 mass%, and more preferably 0.500 mass%, 0.300 mass%, 0.100 mass%, 0.080 mass%, 0.060 mass%, and 0.040 mass% in that order. The lower limit of the CeO2 content is preferably 0.000 mass%, and more preferably 0.005 mass%, 0.010 mass%, 0.015 mass%, and 0.020 mass% in that order. The CeO2 content may even be 0 mass%.

[0171] (Glass properties when glass composition A is used) <Abbe number νd> In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the Abbe number vd is preferably 50, and may be 45, 40, 35, 33, 31, or 30. The lower limit of the Abbe number vd is preferably 15, and may be 17, 18, 19, 20, 21, 22, 23, or 24.

[0172] By setting the Abbe number vd within the above range, a highly dispersive glass can be obtained. The Abbe number νd can be controlled by adjusting the contents of Nb2O5, TiO2, WO3, and Bi2O3, which are glass components that contribute to high dispersion.

[0173] <Refractive index nd> In the glass material for molding according to this embodiment, in the case of glass composition A, the lower limit of the refractive index nd can be 1.65, or even 1.70, 1.72, 1.74, 1.76, or 1.80. The upper limit of the refractive index nd can be 2.30, or even 2.10, 2.00, or 1.90. The refractive index can be controlled by adjusting the contents of Nb2O5, TiO2, WO3, and Bi2O3, which are glass components that contribute to a high refractive index.

[0174] <Glass transition temperature Tg> In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the glass transition temperature Tg is preferably 700°C, 680°C, 670°C, 660°C, 650°C, 640°C, 630°C, 620°C, 610°C, 600°C, 590°C, and 580°C, in that order. The lower limit of the glass transition temperature Tg is not particularly limited, but is preferably 200°C, and more preferably 300°C, 400°C, and 450°C, in that order. The glass transition temperature Tg can be controlled by adjusting the mass ratio [(Li2O + Na2O + KO + Cs2O) / (Nb2O5 + TiO2 + WO3 + Bi2O3)], etc.

[0175] By ensuring that the upper limit of the glass transition temperature Tg satisfies the above range, increases in the molding temperature and annealing temperature during reheating of the glass can be suppressed, and thermal damage to the reheat molding equipment and annealing equipment can be reduced.

[0176] When the lower limit of the glass transition temperature Tg satisfies the above range, the glass of the present invention has the desired Abbe number, refractive index, or transmittance, and is more likely to maintain good formability during reheating and good thermal stability of the glass.

[0177] <Specific gravity> In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of the specific gravity is preferably 4.3, and more preferably 4.1, 4.0, 3.9, 3.8, 3.7, and 3.6 in that order. The lower limit of the specific gravity is not particularly limited, but is usually 2.0, and preferably 2.5.

[0178] The specific gravity is measured using a measurement method with repeatability accuracy within the range of ±0.001 to ±0.002.

[0179] <λτ80> For glass composition A, glass samples with thicknesses of 2.0 mm ± 0.1 mm and 10.0 mm ± 0.1 mm are used to measure the spectral transmittance in the wavelength range of 200 to 700 nm in accordance with JOGIS17 (Method for measuring the internal transmittance of optical glass), and the wavelength at which the internal transmittance of a 10 mm thickness is 80% is defined as λτ80.

[0180] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of λτ80 is preferably 395 nm, and further, the smaller the numerical value, the more preferable in the order of 390 nm, 385 nm, 380 nm, 375 nm, and 370 nm. The lower limit of λτ80 is not particularly limited, but is usually 250 nm, and may be 300 nm or even 320 nm from the viewpoint of suppressing the transmittance of ultraviolet light.

[0181] <λ70> In the case of glass composition A, the spectral transmittance is measured in the wavelength range of 200 to 700 nm for a glass sample having a thickness of 10.0 mm±0.1 mm, and the wavelength at which the external transmittance becomes 70% is defined as λ70.

[0182] In the glass material for molding according to this embodiment, in the case of glass composition A, the upper limit of λ70 is preferably 445 nm, and more preferably 440 nm, 430 nm, 420 nm, 410 nm, 400 nm, 390 nm, and 380 nm in that order. The lower limit of λ70 is not particularly limited, but is usually 255 nm, and may be 305 nm or even 325 nm from the viewpoint of suppressing the transmittance of ultraviolet light.

[0183] In the present invention, glass composition A has a high refractive index yet a small partial dispersion ratio Pg,f. Therefore, even when the cooling rate of the glass in step 3 described below is reduced to one-tenth, variations in the glass's dispersion can be suppressed. For example, in step 3, the change in Abbe number Δνd between the glass obtained at the cooling rate described below and the glass obtained when the cooling rate is reduced to one-tenth is preferably greater than −0.10, more preferably greater than −0.09, with the lower limits being preferably −0.08, −0.07, −0.06, −0.05, −0.04, and −0.03, in that order. Furthermore, from the perspective of effectively correcting chromatic aberration when combined with a low-dispersion lens, the Abbe number νd of the glass material of this embodiment is preferably 50 or less. Therefore, the upper limit of Δνd is +0.10, with the upper limit being more preferably +0.08, +0.06, +0.04, +0.02, and +0.01, in that order. In particular, when the Abbe number is 35 or less, preferably 30 or less, the upper limit of the above Δνd is preferably +0.005, and can also be set to +0.00, −0.01, −0.02, or −0.03.

[0184] <Average linear expansion coefficient α L > In the glass material for molding according to this embodiment, in the case of glass composition A, the average linear expansion coefficient α L The lower limit is preferably 0.70 × 10 -5 °C-1 and 0.71×10 -5 °C -1 , 0.72×10 -5 °C -1 , 0.73×10 -5 °C -1 , 0.74×10 -5 °C -1 , 0.75×10 -5 °C -1 , 0.76×10 -5 °C -1 , 0.77×10 -5 °C -1 , 0.78×10 -5 °C -1 , 0.79×10 -5 °C -1 In addition, the average linear expansion coefficient α L The upper limit of 1.10×10 is set to maintain the stability of the glass and obtain the desired optical properties. -5 °C -1 is an example, and preferably 1.05 × 10 -5 °C -1 is less than or equal to 1.00 x 10 -5 °C -1 , 0.96×10 -5 °C -1 , 0.92×10 -5 °C -1 , 0.88×10 -5 °C -1 , 0.84×10 -5 °C -1 The order of preference is:

[0185] For glass composition A, the average linear expansion coefficient α at -30 to 70°C L By setting the temperature within the above range, it is possible to obtain a glass material for molding that can be used in a wide range of temperature environments.

[0186] Average linear expansion coefficient α L The average linear expansion coefficient α is measured in accordance with the provisions of JOGIS16. The sample is a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm. With a load of 98 mN applied to the sample, it is heated at a constant rate of 4°C per minute, and the temperature and the elongation of the sample are measured in 1-second intervals. Lis the average value of the linear expansion coefficient at -30 to 70°C.

[0187] In addition, in JOGIS16, "the average linear expansion coefficient is 10 -7 °C -1 However, in this specification, the average linear expansion coefficient α L is [10 -5 °C -1 ] is displayed as a unit.

[0188] In this specification, the average linear expansion coefficient α L Regarding [10 -5 °C -1 ], but the unit is [10 -5 ·K -1 Even when using the average linear expansion coefficient α L The numerical values ​​are the same.

[0189] (Glass composition B) Next, the contents and ratios of the glass components and the glass properties when the glass material for molding according to this embodiment has glass composition B will be described.

[0190] In this embodiment, when glass composition B is used, the contents of the glass components SiO2, B2O3, Al2O3, Li2O, Na2O, K2O, Cs2O, MgO, CaO, SrO, BaO, ZnO, La2O3, Gd2O3, Y2O3, ZrO2, TiO2, Nb2O5, WO3, and Bi2O3 expressed in mass% are respectively set to C(SiO 2), C(B2O3), C(Al2O3), C(Li2O), C(Na2O), C(K2O), C(Cs2O), C(MgO), C(CaO), C(SrO), C(BaO), Let C(ZnO), C(La2O3), C(Gd2O3), C(Y2O3), C(ZrO2), C(TiO2), C(Nb2O5), C(WO3), and C(Bi2O3).

[0191] The contents of the glass components Ta2O5, Sc2O3, HfO2, Lu2O3, GeO2, and Yb2O3 other than those mentioned above, expressed in mass%, are C(Ta2O5), C(Sc2O3), C(HfO2), C(Lu2O3), C(GeO2), and C(Yb2O3), respectively.

[0192] In this embodiment, when the glass composition B is used, SiO2, BO 1.5 , AlO 1.5 , LiO 0.5 , NaO 0.5 , K.O. 0.5 , CsO 0.5 , MgO, CaO, SrO, BaO, ZnO, LaO 1.5 , GdO 1.5 ,YO 1.5 , ZrO2, TiO2, NbO 2.5 , WO3, and BiO 1.5 The formula weights of each compound are M(SiO2) and M(BO 1.5 ), M(AlO 1.5 ), M(LiO 0.5 ), M(NaO 0.5 ), M(KO 0.5 ), M(CsO 0.5 ), M(MgO), M(CaO), M(SrO), M(BaO), M(ZnO), M(LaO 1.5 ), M(GdO 1.5 ), M(YO 1.5 ), M(ZrO2), M(TiO2), M(NbO 2.5 ), M(WO3), and M(BiO 1.5 )

[0193] Glass components other than those mentioned above: TaO 2.5 , ScO 1.5 , HfO2, LuO 1.5 , GeO2, and YbO 1.5 The formula weights of each of the compounds are M(TaO 2.5 ), M(ScO 1.5 ), M(HfO2), M(LuO 1.5 ), M(GeO2), and M(YbO 1.5 )

[0194] That is, in this embodiment, when the glass composition B is used, for example, oxide X y O z The content in mass% is C(X y O z ) can be obtained. Also, oxide X y O z The formula weight per mole of cation (cation "X") in z / y The chemical formula in M(XO z / y ) and {C(X y O z ) / M(XO z / y )} is the content of cation "X" in mole percent, i.e., the content of "X" in cationic percent.

[0195] In the glass material for molding according to this embodiment, in the case of glass composition B, A1={C(B2O3) / M(BO 1.5 )} / {C(B2O3) / M(BO 1.5 )+C(SiO2) / M(SiO2)}, the lower limit of A1 is preferably 1 / 3, and more preferably 1.1 / 3, 1.2 / 3, 1.3 / 3, 1.4 / 3, 1.5 / 3, 1.6 / 3, 1.7 / 3, 1.8 / 3, and 1.9 / 3 in that order. The upper limit of A1 is preferably 3.0 / 3, and more preferably 2.9 / 3, 2.8 / 3, 2.7 / 3, 2.6 / 3, 2.5 / 3, 2.4 / 3, and 2.3 / 3 in that order.

[0196] In the glass composition B, by setting A1 in the above range, the average linear expansion coefficient α L It is possible to obtain a molding glass material with a large refractive index and low dispersion. In addition, the temperature coefficient of the relative refractive index (dn / dT) of the glass can be reduced. Furthermore, even when a large amount of La2O3 is contained, the deterioration of the thermal stability of the glass can be suppressed. On the other hand, if A1 is too small, the refractive index nd increases and the average linear expansion coefficient α L If the glass contains a large amount of La2O3 and Y2O3, which are glass components that prevent the deterioration of the glass's chemical properties, the glass may become unstable. Also, if A1 is too large, the stability, chemical durability, and mechanical properties of the glass may decrease.

[0197] In the glass material for molding according to this embodiment, in the case of glass composition B, B1={C(BaO) / M(BaO)+C(SrO) / M(SrO)} / {C(LiO) / M(LiO 0.5 ) + C(NaO) / M(NaO 0.5 ) + C(KO) / M(KO 0.5 ) + C(CsO) / M(CsO 0.5 ) + C(MgO) / M(MgO) + C(CaO) / M(CaO) + C(SrO) / M(SrO) + C(BaO) / M(BaO)}, the lower limit of B1 is preferably 0.62, and more preferably 0.63, 0.65, 0.67, 0.69, 0.71, 0.73, 0.75, 0.77, 0.79, 0.81, 0.83, 0.85, and 0.87, in that order. The upper limit of B1 is preferably 1.00, and more preferably 0.99 and 0.98, in that order. B1 may be 1.00.

[0198] In the glass composition B, by setting B1 in the above range, the average linear expansion coefficient α L A glass material for molding with a high refractive index and a large average linear expansion coefficient α L On the other hand, if B1 is too small, the average linear expansion coefficient α L In addition, the refractive index nd decreases, and the stability of the glass may be impaired.

[0199] In the glass material for molding according to this embodiment, in the case of glass composition B, C1 = {C(BaO) / M(BaO)+C(LiO) / M(LiO 0.5 )} / {C(NaO) / M(NaO 0.5 ) + C(KO) / M(KO 0.5 )+C(SiO2) / M(SiO2)+C(TiO2) / M(TiO2)+C(Nb2O5) / M(NbO 2.5) + C(WO3) / M(WO3)}, the lower limit of C1 is preferably 8 / 9, and more preferably 8.2 / 9, 8.4 / 9, 8.6 / 9, 8.8 / 9, 9.0 / 9, 9.2 / 9, 9.4 / 9, and 9.5 / 9 in that order. The upper limit of C1 is preferably 27 / 9, and more preferably 25 / 9, 23 / 9, 21 / 9, 19 / 9, 17 / 9, 15 / 9, 13 / 9, and 12 / 9 in that order.

[0200] In the glass composition B, by setting C1 in the above range, the average linear expansion coefficient α L A molding glass material with a high refractive index and low dispersion can be obtained. In addition, the temperature coefficient of the relative refractive index (dn / dT) of the glass can be reduced. On the other hand, if C1 is too small, the average linear expansion coefficient α L If C1 is too large, the stability of the glass may decrease.

[0201] In the glass material for molding according to this embodiment, in the case of glass composition B, when D1 = C(Gd2O3) + C(ZnO) + C(TiO2) + C(Nb2O5) + C(WO3) + C(ZrO2), the upper limit of D1 is preferably 13.50, and more preferably 12.00, 11.00, 10.50, 10.00, 9.50, 9.00, and 8.50 in that order. The lower limit of D1 is preferably 0, and more preferably 1, 2, 3, 4, 5, 6, 7, and 8 in that order. D1 may also be 0.

[0202] In the glass composition B, by setting D1 in the above range, the average linear expansion coefficient α L This can prevent a decrease in refractive index. Also, by preventing high dispersion, a molding glass material with high refractive index and low dispersion can be obtained. Furthermore, it has the effect of preventing an increase in the temperature coefficient of the relative refractive index (dn / dT) of the glass. D1 may be 0, but D1 can also be made larger than 0 in order to adjust optical constants such as the Abbe number νd. On the other hand, if D1 is too large, the average linear expansion coefficient α L This may result in a decrease in the refractive index and a loss of the high refractive index and low dispersion properties of the glass.

[0203] In the glass material for molding according to this embodiment, in the case of glass composition B, when E1={C(La2O3)+C(Gd2O3)+C(Y2O3)} / {C(SiO2)+C(B2O3)+C(Al2O3)}, the lower limit of E1 is preferably 1.25, and more preferably 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, and 1.70 in that order. The upper limit of E1 is preferably 3.00, and more preferably 2.80, 2.60, 2.40, 2.20, and 2.10 in that order.

[0204] In glass composition B, by setting E1 within the above range, a molding glass material with high refractive index and low dispersion can be obtained. On the other hand, if E1 is too small, the high refractive index and high dispersion properties of the glass are lost, and the average linear expansion coefficient α L Furthermore, if E1 is too large, the thermal stability of the glass may decrease.

[0205] In the glass material for molding according to this embodiment, in the case of glass composition B, F1={C(GdO) / M(GdO 1.5 )+C(ZnO) / M(ZnO)+C(TiO2) / M(TiO2)+C(Nb2O5) / M(NbO 2.5 )+C(WO3) / M(WO3)+C(Bi2O3) / M(BiO 1.5 )} / {C(Y2O3) / M(YO 1.5 )}, the upper limit of F1 is preferably 2.0, and more preferably 1.8, 1.6, 1.4, 1.2, 1.1, 1.0, 0.9, 0.8, and 0.6 in that order. The lower limit of F1 is preferably 0, and more preferably 0.1, 0.2, 0.3, and 0.4 in that order. F1 may be 0.

[0206] In the glass composition B, by setting F1 in the above range, the average linear expansion coefficient α L A molding glass material with a large coefficient of thermal expansion (F1) can be obtained. Furthermore, a decrease in the thermal stability of the glass can be suppressed. F1 may be 0, but F1 can also be made larger than 0 in order to adjust optical constants such as the Abbe number νd. On the other hand, if F1 is too large, the average linear expansion coefficient α LThis may result in a decrease in the refractive index and a loss of the high refractive index and low dispersion properties of the glass.

[0207] In the glass material for molding according to this embodiment, in the case of glass composition B, G1 = C(BaO) / M(BaO) + C(LaO) / M(LaO 1.5 ) + C(LiO) / M(LiO 0.5 )+C(Y2O3) / M(YO 1.5 ), the lower limit of G1 is preferably 0.47, and more preferably 0.475, 0.48, and 0.485 in that order. The upper limit of G1 is preferably 0.60, and more preferably 0.59, 0.58, 0.57, 0.56, 0.55, 0.54, and 0.53 in that order.

[0208] In glass composition B, the average linear expansion coefficient α L From the viewpoint of suppressing the decrease in the average linear expansion coefficient α and obtaining a molding glass material with a high refractive index and low dispersion, it is preferable to set G1 within the above range. L If G1 is too large, the thermal stability of the glass may decrease.

[0209] In this embodiment, in the case of glass composition B, {C(B2O3) / M(BO 1.5 The lower limit of {(SiO2)+C(SiO2) / M(SiO2)} is preferably 0.35, and more preferably 0.37, 0.39, 0.41, 0.43, 0.45, and 0.47 in that order. The upper limit is preferably 0.75, and more preferably 0.73, 0.71, 0.69, 0.67, 0.65, 0.63, 0.61, and 0.59 in that order.

[0210] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a glass material for molding with large and low dispersion, {C(B2O3) / M(BO 1.5 )+C(SiO2) / M(SiO2)} is preferably in the above range.

[0211] In this embodiment, for glass composition B, the lower limit of {C(BaO) / M(BaO)+C(SrO) / M(SrO)} is preferably 0.15, and more preferably 0.16, 0.17, 0.18, 0.19, and 0.20 in that order. The upper limit is preferably 0.30, and more preferably 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, and 0.23 in that order.

[0212] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a large refractive index and a high refractive index, it is preferable that {C(BaO) / M(BaO)+C(SrO) / M(SrO)} be in the above range.

[0213] In this embodiment, in the case of glass composition B, {C(LiO) / M(LiO 0.5 ) + C(NaO) / M(NaO 0.5 ) + C(KO) / M(KO 0.5 ) + C(CsO) / M(CsO 0.5 The lower limit of the ratio {C(MgO) / M(MgO)+C(CaO) / M(CaO)+C(SrO) / M(SrO)+C(BaO) / M(BaO)} is preferably 0.15, and more preferably 0.16, 0.17, 0.18, 0.19, and 0.20 in that order. The upper limit is preferably 0.35, and more preferably 0.34, 0.33, 0.32, 0.31, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, and 0.23 in that order.

[0214] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a glass material for molding with a high refractive index, {C(LiO) / M(LiO 0.5 ) + C(NaO) / M(NaO 0.5 ) + C(KO) / M(KO 0.5 ) + C(CsO) / M(CsO 0.5 ) + C(MgO) / M(MgO) + C(CaO) / M(CaO) + C(SrO) / M(SrO) + C(BaO) / M(BaO)} is preferably in the above range.

[0215] In this embodiment, in the case of glass composition B, {C(BaO) / M(BaO)+C(LiO) / M(LiO 0.5 )} is preferably 0.15, and more preferably 0.16, 0.17, 0.18, 0.19, and 0.20 in that order. The upper limit is preferably 0.35, and more preferably 0.34, 0.33, 0.32, 0.31, 0.30, 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, and 0.23 in that order.

[0216] In glass composition B, the average linear expansion coefficient α L In order to obtain a molding glass material with a high refractive index and low dispersion, {C(BaO) / M(BaO)+C(LiO) / M(LiO) 0.5 )} is preferably within the above range.

[0217] In this embodiment, in the case of glass composition B, {C(NaO) / M(NaO 0.5 ) + C(KO) / M(KO 0.5 )+C(SiO2) / M(SiO2)+C(TiO2) / M(TiO2)+C(Nb2O5) / M(NbO 2.5 The lower limit of {C(WO3) / M(WO3)} is preferably 0.05, and more preferably 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, and 0.16 in this order. The upper limit is preferably 0.30, and more preferably 0.29, 0.28, 0.27, 0.26, 0.25, 0.24, 0.23, 0.22, and 0.21 in this order.

[0218] In glass composition B, the average linear expansion coefficient α L In order to obtain a molding glass material with a high refractive index and low dispersion, C(NaO) / M(NaO 0.5 ) + C(KO) / M(KO 0.5 )+C(SiO2) / M(SiO2)+C(TiO2) / M(TiO2)+C(Nb2O5) / M(NbO 2.5 )+C(WO3) / M(WO3)} is preferably in the above range.

[0219] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [C(BaO) / {C(SiO)+C(TiO)+C(NbO)+C(WO)}] is preferably 1.0, and more preferably 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, and 2.4 in that order. The upper limit of this mass ratio is preferably 5.5, and more preferably 5.3, 5.1, 4.9, 4.7, 4.5, 4.3, 4.1, 3.9, 3.7, and 3.5 in that order.

[0220] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, and from the viewpoint of reducing the temperature coefficient of the relative refractive index (dn / dT), it is preferable that the mass ratio [C(BaO) / {C(SiO)+C(TiO)+C(NbO)+C(WO)}] be within the above range.

[0221] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [C(BaO) / {C(SiO)+C(B2O3)+C(TiO2)+C(Nb2O5)+C(WO3)}] is preferably 0.80, and more preferably 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, and 1.20 in that order. The upper limit of this mass ratio is preferably 1.70, and more preferably 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, and 1.35 in that order.

[0222] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, and from the viewpoint of reducing the temperature dependence of the temperature coefficient of the relative refractive index (dn / dT), it is preferable that the mass ratio [C(BaO) / {C(SiO)+C(B)O)+C(TiO)+C(NbO)+C(WO)}] be within the above range.

[0223] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [{C(BaO)+C(LiO)+C(SrO)} / {C(SiO)+C(TiO)+C(NbO)+C(WO)}] is preferably 0.5, and more preferably 1.0, 1.5, 2.0, 2.2, and 2.4 in that order. The upper limit of this mass ratio is preferably 7.0, and more preferably 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, and 3.5 in that order.

[0224] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, it is preferable that the mass ratio [{C(BaO)+C(LiO)+C(SrO)} / {C(SiO)+C(TiO)+C(NbO)+C(WO)}] be within the above range.

[0225] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [{C(LiO)+C(NaO)+C(KO)+C(CsO)+C(CaO)+C(SrO)+C(BaO)} / {C(SiO)+C(TiO)+C(NbO)+C(WO)}] is preferably 0.5, and more preferably 1.0, 1.5, 2.0, 2.2, and 2.4 in that order. The upper limit of this mass ratio is preferably 7.0, and more preferably 6.5, 6.0, 5.5, 5.0, 4.5, 4.0, and 3.5 in that order.

[0226] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, it is preferable that the mass ratio [{C(LiO)+C(NaO)+C(KO)+C(CsO)+C(CaO)+C(SrO)+C(BaO)} / {C(SiO)+C(TiO)+C(NbO)+C(WO)}] be within the above range.

[0227] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the total content [C(ZnO)+C(Gd2O3)+C(TiO2)+C(Nb2O5)+C(WO3)] is preferably 0, and more preferably 1, 2, 3, 4, and 5 in that order. The total content may be 0. The upper limit of the total content is preferably 15, and more preferably 14, 13, 12, 11, 10, 9, 8, 7, and 6 in that order.

[0228] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a glass material for molding with high specific gravity and low dispersion, it is preferable that the total content [C(ZnO)+C(Gd2O3)+C(TiO2)+C(Nb2O5)+C(WO3)] be within the above range.

[0229] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the total content [C(SiO2)+C(ZnO)+C(Gd2O3)+C(TiO2)+C(Nb2O5)+C(WO3)] is preferably 5, and more preferably 6, 7, 8, and 9. The upper limit of the total content is preferably 25, and more preferably 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, and 14, in that order.

[0230] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, it is preferable that the total content [C(SiO2) + C(ZnO) + C(Gd2O3) + C(TiO2) + C(Nb2O5) + C(WO3)] be within the above range.

[0231] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the total content [C(SiO2)+C(ZnO)+C(Gd2O3)+C(ZrO2)+C(TiO2)+C(Nb2O5)+C(WO3)] is preferably 5, and more preferably 6, 7, 8, and 9 in that order. The upper limit of the total content is preferably 25, and more preferably 24, 23, 22, 21, 20, 19, 18, 17, and 16 in that order.

[0232] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a large refractive index and low dispersion, it is preferable that the total content [C(SiO2) + C(ZnO) + C(Gd2O3) + C(ZrO2) + C(TiO2) + C(Nb2O5) + C(WO3)] be within the above range.

[0233] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the total content [C(Al2O3)+C(SiO2)+C(ZnO)+C(Gd2O3)+C(ZrO2)+C(TiO2)+C(Nb2O5)+C(WO3)] is preferably 5, and more preferably 6, 7, 8, and 9. The upper limit of the total content is preferably 25, and more preferably 24, 23, 22, 21, 20, 19, 18, 17, and 16, in that order.

[0234] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a large refractive index and low dispersion, it is preferable that the total content [C(Al2O3) + C(SiO2) + C(ZnO) + C(Gd2O3) + C(ZrO2) + C(TiO2) + C(Nb2O5) + C(WO3)] be within the above range.

[0235] In the present embodiment, in the case of glass composition B, the lower limit of the total content [C(La2O3)+C(Gd2O3)+C(Y2O3)] is preferably 25, and more preferably 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, and 38, in that order. The upper limit of the total content is preferably 50, and more preferably 49, 48, 47, 46, 45, 44, and 43, in that order.

[0236] In glass composition B, the total content [C(La2O3)+C(Gd2O3)+C(Y2O3)] is preferably within the above range, from the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion.

[0237] In the present embodiment, in the case of glass composition B, the lower limit of the total content [C(SiO2)+C(B2O3)+C(Al2O3)] is preferably 15, and more preferably 16, 17, 18, and 19 in that order. The upper limit of the total content is preferably 30, and more preferably 29, 28, 27, 26, and 25 in that order.

[0238] In glass composition B, from the viewpoint of obtaining a high-refractive-index, low-dispersion glass material for molding without decreasing the refractive index as much as possible, it is preferable that the total content [C(SiO2)+C(B2O3)+C(Al2O3)] be within the above range.

[0239] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [{C(LaO)+C(GdO)+C(YO)} / {2×C(SiO)+C(BO)+C(AlO)}] is preferably 1.00, and more preferably 1.05, 1.10, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, and 1.21 in that order. The upper limit of this mass ratio is preferably 1.80, and more preferably 1.75, 1.70, 1.65, 1.60, 1.55, 1.54, 1.53, 1.52, 1.51, and 1.50 in that order.

[0240] In glass composition B, from the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, it is preferable that the mass ratio [{C(La2O3)+C(Gd2O3)+C(Y2O3)} / {2×C(SiO2)+C(B2O3)+C(Al2O3)}] be in the above range.

[0241] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the total content [2 × C(SiO2) + C(B2O3) + C(Al2O3)] is preferably 20, and more preferably 21, 22, 23, 24, 25, and 26 in that order. The upper limit of the total content is preferably 45, and more preferably 44, 43, 42, 41, 40, 39, 38, 37, 36, and 35 in that order.

[0242] In glass composition B, the average linear expansion coefficient α L From the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, the total content [2×C(SiO2)+C(B2O3)+C(Al2O3)] is preferably within the above range.

[0243] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [{C(LaO)+C(YO)} / {C(BO)+C(BaO)}] is preferably 0.50, and more preferably 0.55, 0.60, 0.65, 0.70, 0.75, and 0.80 in that order. The upper limit of this mass ratio is preferably 1.30, and more preferably 1.25, 1.20, 1.15, 1.10, 1.05, 1.00, 0.95, and 0.92 in that order.

[0244] In glass composition B, from the viewpoint of obtaining a molding glass material with a high refractive index and low dispersion, it is preferable that the mass ratio [{C(La2O3)+C(Y2O3)} / {C(B2O3)+C(BaO)}] be in the above range.

[0245] In this embodiment, in the case of glass composition B, [C(GdO) / M(GdO 1.5 )+C(ZnO) / M(ZnO)+C(TiO2) / M(TiO2)+C(Nb2O5) / M(NbO 2.5 )+C(WO3) / M(WO3)+C(Bi2O3) / M(BiO 1.5 The lower limit of ( ) is preferably 0, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, and 0.06 in that order. The value may be 0. The upper limit is preferably 0.30, and more preferably 0.25, 0.20, 0.18, 0.16, 0.14, 0.12, 0.10, and 0.08 in that order.

[0246] In glass composition B, the average linear expansion coefficient α L In order to suppress the deterioration of the thermal stability of the glass, [C(Gd2O3) / M(GdO 1.5 )+C(ZnO) / M(ZnO)+C(TiO2) / M(TiO2)+C(Nb2O5) / M(NbO2.5 )+C(WO3) / M(WO3)+C(Bi2O3) / M(BiO 1.5 )] is preferably in the above range.

[0247] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [C(Y2O3) / {C(La2O3)+C(Y2O3)+C(Gd2O3)}] is preferably 0.20, and more preferably 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, and 0.34, in that order. The upper limit of this mass ratio is preferably 0.60, and more preferably 0.59, 0.58, 0.57, 0.56, 0.55, 0.54, 0.53, 0.52, 0.51, 0.50, 0.49, 0.48, 0.47, and 0.46, in that order.

[0248] In glass composition B, the average linear expansion coefficient α L From the viewpoint of suppressing a decrease in the thermal stability of the glass, it is preferable that the mass ratio [C(Y2O3) / {C(La2O3)+C(Y2O3)+C(Gd2O3)}] be set in the above range.

[0249] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the mass ratio [C(Y2O3) / {C(La2O3)+C(Y2O3)+C(TiO2)}] is preferably 0.20, and more preferably 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, and 0.32, in that order. The upper limit of this mass ratio is preferably 0.50, and more preferably 0.49, 0.48, 0.47, 0.46, and 0.45, in that order.

[0250] In glass composition B, the average linear expansion coefficient α L From the viewpoint of suppressing a decrease in the thermal stability of the glass, it is preferable that the mass ratio [C(Y2O3) / {C(La2O3)+C(Y2O3)+C(TiO2)}] be in the above range.

[0251] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the total content [C(BaO)+C(La2O3)+C(Y2O3)] is preferably 50, and more preferably 52, 54, 56, 58, 60, 62, 64, 66, 68, and 70, in that order. The upper limit of the total content is preferably 85, and more preferably 83, 81, 79, 77, and 76, in that order.

[0252] In glass composition B, the average linear expansion coefficient α L From the viewpoint of suppressing the decrease in refractive index and obtaining a molding glass material with a high refractive index and low dispersion, it is preferable that the total content [C(BaO)+C(La2O3)+C(Y2O3)] be in the above range.

[0253] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the SiO content is preferably 3.0%, and more preferably 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, and 7.0% in that order. The upper limit of the SiO content is preferably 15.0%, and more preferably 14.5%, 14.0%, 13.5%, 13.0%, 12.5%, 12.0%, 11.5%, 11.0%, 10.5%, and 10.0% in that order.

[0254] SiO2 is a glass network-forming component in glass composition B, and has the functions of improving the thermal stability, chemical durability, and weather resistance of glass, increasing the viscosity of molten glass, and making it easier to form molten glass. SiO2 also has a stronger effect of increasing the value of ΔPg,F than, for example, La2O3, BaO, and Y2O3, which are contained in large amounts in glass composition B. On the other hand, when the SiO2 content is high, the average linear expansion coefficient α L The refractive index nd may decrease, and the SiO2 content may decrease. If the SiO2 content is too low, the stability during reheating may decrease. Therefore, it is preferable that the SiO2 content be in the above range.

[0255] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the B2O3 content is preferably 8.0%, and more preferably 8.5%, 9.0%, 9.5%, 10.0%, 10.5%, 11.0%, 11.5%, and 12.0% in that order. The upper limit of the B2O3 content is preferably 20.0%, and more preferably 19.5%, 19.0%, 18.5%, 18.0%, 17.5%, 17.0%, 16.5%, 16.0%, 15.5%, and 15.0% in that order.

[0256] B2O3 is a glass network forming component in glass composition B and has the function of improving the thermal stability of the glass. In addition, among the network forming components, it has a relatively low average linear expansion coefficient α L It is a component that does not decrease the refractive index nd. Furthermore, from the viewpoint of obtaining a glass with a high refractive index nd without impairing low dispersion, the content of B2O3 can be set within the above range. On the other hand, if the content of B2O3 is too high, the refractive index nd may decrease. Furthermore, if the content of B2O3 is too low, the stability during reheating may deteriorate.

[0257] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Al2O3 content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the Al2O3 content is preferably 0%. The Al2O3 content may be 0%.

[0258] In glass composition B, Al2O3 is a glass component that improves the chemical durability and weather resistance of the glass and can be considered a network-forming component. On the other hand, if the Al2O3 content is too high, the refractive index nd decreases, and the thermal stability and meltability of the glass may decrease. Therefore, it is preferable that the Al2O3 content be within the above range.

[0259] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the P2O5 content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the P2O5 content is preferably 0%. The P2O5 content may be 0%.

[0260] In glass composition B, P2O5 is a component that lowers the refractive index nd and also lowers the thermal stability of the glass, so the content of P2O5 is preferably within the above range.

[0261] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Li2O content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the Li2O content is preferably 0%. The Li2O content may be 0%.

[0262] Li2O is a component in glass composition B that contributes to lowering the specific gravity of the glass, improves the meltability of the glass, and reduces the average linear expansion coefficient α L LiO has the function of increasing the refractive index. Furthermore, it is a component that contributes to lowering the glass transition temperature Tg, which contributes to improving moldability during precision press molding. Furthermore, from the viewpoint of obtaining a glass with a high refractive index nd without sacrificing low dispersion, the content of LiO can be set within the above range. On the other hand, if the content of LiO is too high, there is a risk that devitrification resistance and acid resistance will decrease. There is also a risk that low dispersion will be impaired.

[0263] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Na2O content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the Na2O content is preferably 0%. The Na2O content may be 0%.

[0264] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the K2O content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1% in that order. The lower limit of the K2O content is preferably 0%. The K2O content may be 0%.

[0265] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the total content of Na2O and KO is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.001%, 0.01%, and 0.05% in that order.

[0266] In glass composition B, Na2O and K2O both function to improve the meltability of the glass. They also function to increase the average linear thermal expansion coefficient. On the other hand, if their contents increase, the thermal stability, devitrification resistance, chemical durability, and weather resistance decrease. Therefore, it is preferable that the respective contents of Na2O and K2O and their total content are within the above ranges.

[0267] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the CsO content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the CsO content is preferably 0%. The CsO content may be 0%.

[0268] In glass composition B, CsO functions to improve the meltability of the glass, but if the content is too high, the thermal stability and refractive index nd of the glass will decrease, and volatilization of glass components during melting will increase, which may make it impossible to obtain the desired glass. Therefore, the CsO content is preferably within the above range.

[0269] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the total content of Li2O, Na2O, K2O, and Cs2O is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the total content is preferably 0%. The total content may be 0%. From the viewpoint of suppressing an increase in the liquidus temperature of the glass, it is preferable that the total content of Li2O, Na2O, K2O, and Cs2O be within the above range.

[0270] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the MgO content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the MgO content is preferably 0%. The MgO content may be 0%.

[0271] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the CaO content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.2%, and 0.1%, in that order. The lower limit of the CaO content is preferably 0%. The CaO content may be 0%.

[0272] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the SrO content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.4%, and 0.3%, in that order. The lower limit of the SrO content is preferably 0%, and more preferably 0.05%, 0.10%, 0.15%, and 0.20%, in that order.

[0273] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the total content of MgO, CaO, and SrO is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.4%, and 0.3% in that order. The lower limit of the total content is preferably 0%, and more preferably 0.05%, 0.10%, 0.15%, and 0.20% in that order. The total content may even be 0%.

[0274] In glass composition B, MgO, CaO, and SrO are glass components that improve the meltability of the glass and also relatively increase the average linear expansion coefficient. However, if the content of these glass components increases, the thermal stability and devitrification resistance of the glass decrease. Therefore, the individual contents and the total content of these glass components are preferably within the above ranges.

[0275] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the BaO content is preferably 20%, and more preferably 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, and 31% in that order. The upper limit of the BaO content is preferably 45%, and more preferably 44%, 43%, 42%, 41%, 40%, 39%, 38%, 37%, 36%, 35%, and 34% in that order.

[0276] In glass composition B, BaO has a low mean linear expansion coefficient α without impairing the high refractive index and low dispersion characteristics. L It is a glass component that has the function of increasing the refractive index and also serves to relatively reduce the value of ΔPg,F. By setting the content of BaO within the above range, it is possible to obtain a glass having a high refractive index and low dispersion, and a mean linear expansion coefficient α L On the other hand, if the BaO content is too high, the thermal stability of the glass may decrease, causing the glass to devitrify and resulting in poor stability during reheating.

[0277] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the total content of SiO2 and B2O3 is preferably 30%, and more preferably 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, and 20% in that order. The lower limit of the total content is preferably 13%, and more preferably 14%, 15%, 16%, 17%, and 18% in that order.

[0278] In glass composition B, the total content of SiO2 and B2O3 is preferably within the above range, from the viewpoint of suppressing a decrease in the refractive index while maintaining the stability of the glass.

[0279] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the mass ratio of the BaO content to the total content of SiO and B O [BaO / (SiO + B O)] is preferably 3.00, and more preferably 2.80, 2.60, 2.40, 2.20, 2.00, 1.80, and 1.70 in that order. The lower limit of this mass ratio is preferably 0.60, and more preferably 0.80, 0.90, 1.00, 1.10, 1.20, and 1.30 in that order.

[0280] In the glass composition B, the stability of the glass is maintained and the average linear expansion coefficient α L From the viewpoint of obtaining a glass having a large σ, the mass ratio is preferably within the above range.

[0281] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the ZnO content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, 0.03%, 0.02%, and 0.01% in that order. The lower limit of the ZnO content is preferably 0%. The ZnO content may be 0%.

[0282] ZnO is a glass component that functions to improve the meltability of glass in glass composition B. However, if the ZnO content is too high, the specific gravity of the glass increases and the average linear expansion coefficient αL The ZnO content may be lowered. Also, the low dispersion of the glass may be impaired. Furthermore, the glass transition temperature Tg may be lowered. Therefore, the ZnO content is preferably within the above range.

[0283] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the La2O3 content is preferably 15%, and more preferably 16%, 17%, 18%, 19%, 20%, 21%, and 22% in that order. The upper limit of the La2O3 content is preferably 40%, and more preferably 39%, 38%, 37%, 36%, 35%, 34%, 33%, 32%, 31%, 30%, 29%, and 28% in that order.

[0284] La2O3 is a glass component in glass composition B that acts to increase the refractive index while suppressing a decrease in the Abbe number νd. It is also a component that reduces the partial dispersion ratio Pg,F, and has a stronger effect of reducing the value of ΔPg,F than BaO. Therefore, by setting the content of La2O3 within the above range, it is possible to achieve a high refractive index, low dispersion, and a mean linear expansion coefficient α L This results in a glass material for molding that suppresses a decrease in the temperature coefficient of the relative refractive index (dn / dT) and suppresses an increase in the temperature coefficient of the relative refractive index (dn / dT). On the other hand, if the La2O3 content is too high, the thermal stability and devitrification resistance of the glass may decrease, and stability during reheating may also deteriorate.

[0285] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Gd2O3 content is preferably 20%, and more preferably 15%, 10%, 5%, 4%, 3%, 2%, 1%, and 0.5%, in that order. The lower limit of the Gd2O3 content is preferably 0%. The Gd2O3 content may be 0%.

[0286] In glass composition B, Gd2O3 has high refractive index and low dispersion, and has a mean linear expansion coefficient α LHowever, in the glass of the present embodiment, which incorporates a large amount of BaO, if the Gd2O3 content is too high, the thermal stability and devitrification resistance of the glass decrease, and the glass becomes more susceptible to devitrification during production. Furthermore, if the Gd2O3 content is too high, the specific gravity of the glass increases, which is undesirable. It is also disadvantageous from the viewpoint of reducing raw material costs. Therefore, it is preferable that the Gd2O3 content be within the above range.

[0287] In the glass material for molding according to this embodiment, in the case of glass composition B, the lower limit of the Y2O3 content is preferably 5%, and more preferably 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, and 14% in that order. The upper limit of the Y2O3 content is preferably 25%, and more preferably 24%, 23%, 22%, 21%, 20%, and 19% in that order.

[0288] Y2O3 is a component that acts to increase the refractive index while suppressing a decrease in the Abbe number νd in the glass composition B. In addition, in the glass of this embodiment in which a relatively large amount of BaO or SrO is introduced among the alkali components and alkaline earth components, the average linear expansion coefficient α L It is an effective component for suppressing the decrease in refractive index and imparting high refractive index and low dispersion characteristics. It also improves the chemical durability and weather resistance of the glass and increases the glass transition temperature. It is a component that reduces the partial dispersion ratio Pg,F and also reduces the value of ΔPg,F. On the other hand, if the Y2O3 content is too high, the thermal stability and devitrification resistance of the glass may decrease. There is also a risk of deterioration in stability during reheating. Therefore, it is preferable that the Y2O3 content be within the above range.

[0289] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the ZrO2 content is preferably 10%, and more preferably 9%, 8%, 7%, 6%, 5%, 4%, 3%, and 2.5% in that order. The lower limit of the ZrO2 content is preferably 0%, and more preferably 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1.0%, 1.5%, and 2.0% in that order. The ZrO2 content may even be 0%.

[0290] ZrO2 is a component in glass composition B that increases the refractive index, and by adding an appropriate amount, it also improves the thermal stability of the glass. However, ZrO2 has a low average linear expansion coefficient α L ZrO2 is a component that relatively reduces the refractive index, and also increases the temperature dependence of the temperature coefficient of the relative refractive index (dn / dT). If the content is too high, the thermal stability may be significantly reduced. Therefore, it is preferable that the content of ZrO2 be within the above range.

[0291] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the TiO2 content is preferably 15%, and more preferably 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, and 6% in that order. The lower limit of the TiO2 content is preferably 0%, and more preferably 1%, 2%, 3%, 4%, and 5% in that order. The TiO2 content may even be 0%.

[0292] TiO2 is a component in glass composition B that increases the refractive index, and when included in an appropriate amount, it also improves the thermal stability of the glass. TiO2 is a component that increases the partial dispersion ratio Pg,F, and has a stronger effect on increasing the values ​​of Pg,F and ΔPg,F compared to Nb2O5. On the other hand, if the TiO2 content is too high, the average linear expansion coefficient α L In addition, the Abbe number νd may decrease, the coloring of the glass may become stronger, and the melting property may deteriorate. There is also a risk of deterioration in stability during reheating. Therefore, it is preferable that the TiO2 content be within the above range.

[0293] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Nb2O5 content is preferably 20%, and more preferably 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 5%, 3%, 2%, and 1% in that order. The lower limit of the Nb2O5 content is preferably 0%, and more preferably 0.001%, 0.003%, 0.005%, 0.010%, 0.050%, 0.080%, and 0.100% in that order. The Nb2O5 content may even be 0%.

[0294] Nb2O5 is a component in glass composition B that increases the refractive index, and when included in an appropriate amount, it also improves the thermal stability of the glass. Nb2O5 is also a component that increases the partial dispersion ratios Pg,F and ΔPg,F. On the other hand, if the Nb2O5 content is too high, the average linear expansion coefficient α L In addition, the glass may become more colored. Stability during reheating may also be impaired. Therefore, the content of Nb2O5 is preferably within the above range.

[0295] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the WO3 content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, and 0.1% in that order. The lower limit of the WO3 content is preferably 0%. The WO3 content may be 0%.

[0296] In glass composition B, WO3 has the function of lowering the glass transition temperature Tg relative to other highly dispersive components, and therefore can be incorporated for the purpose of lowering the molding temperature to protect the molding die, its protective film, and the molding machine when softening and molding the glass, particularly when precision pressing is performed. On the other hand, from the viewpoints of increasing the transmittance of the glass and suppressing an increase in the temperature coefficient of the relative refractive index (dn / dT) of the glass, the content of WO3 is preferably within the above range.

[0297] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Bi2O3 content is preferably 10%, and more preferably 8%, 6%, 4%, 2%, 1%, 0.5%, and 0.1% in that order. The lower limit of the Bi2O3 content is preferably 0%. The Bi2O3 content may be 0%.

[0298] In glass composition B, Bi2O3 is a component that increases the refractive index nd while decreasing the Abbe number νd. It is also a component that tends to increase the coloration of the glass. Therefore, the Bi2O3 content is preferably within the above range.

[0299] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Ta2O5 content is preferably 20%, and more preferably 15%, 13%, 10%, 5%, 3%, and 1% in that order. The lower limit of the Ta2O5 content is preferably 0%. The Ta2O5 content may be 0%.

[0300] Ta2O5 is a glass component in glass composition B that functions to improve the thermal stability and devitrification resistance of the glass. On the other hand, Ta2O5 increases the refractive index and makes the glass highly dispersible. In addition, if the content of Ta2O5 increases, the thermal stability of the glass decreases, and when the glass is melted, the glass raw materials tend to remain unmelted. In addition, the average linear expansion coefficient α L Ta2O5 is a component that relatively reduces the glass viscosity. Therefore, the content of Ta2O5 is preferably within the above range. Furthermore, Ta2O5 is an extremely expensive component compared to other glass components, and a high Ta2O5 content increases the glass production cost. Furthermore, Ta2O5 has a larger molecular weight than other glass components, so it increases the specific gravity of the glass, resulting in an increase in the weight of the optical element.

[0301] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Sc2O3 content is preferably 2%, and the lower limit of the Sc2O3 content is preferably 0%.

[0302] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the HfO2 content is preferably 2%. The lower limit of the HfO2 content is preferably 0%.

[0303] In glass composition B, Sc2O3 and HfO2 both have the function of increasing the refractive index nd and are expensive components, so the contents of Sc2O3 and HfO2 are preferably within the above ranges.

[0304] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Lu2O3 content is preferably 2%, and the lower limit of the Lu2O3 content is preferably 0%.

[0305] Lu2O3 has the function of increasing the refractive index nd in glass composition B. It is also a glass component that increases the specific gravity of the glass due to its large molecular weight. Therefore, the content of Lu2O3 is preferably within the above range.

[0306] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the GeO2 content is preferably 2%. The lower limit of the GeO2 content is preferably 0%.

[0307] GeO2 has the function of increasing the refractive index nd in glass composition B, and is an extremely expensive component among commonly used glass components. Therefore, from the viewpoint of reducing the manufacturing cost of the glass, it is preferable that the content of GeO2 be in the above range.

[0308] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the La2O3 content is preferably 2%. The lower limit of the La2O3 content is preferably 0%. The La2O3 content may be 0%.

[0309] In glass composition B, if the content of La2O3 is large, the thermal stability and devitrification resistance of the glass decrease, and the glass becomes more susceptible to devitrification during production. Therefore, from the viewpoint of suppressing the decrease in thermal stability and devitrification resistance, the content of La2O3 is preferably within the above range.

[0310] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the Yb2O3 content is preferably 2%. %.

[0311] In glass composition B, if the Yb2O3 content is too high, the thermal stability and devitrification resistance of the glass may decrease. Furthermore, Yb2O3 is an expensive component among commonly used glass components. From the viewpoints of preventing a decrease in the thermal stability of the glass, suppressing an increase in specific gravity, and reducing the manufacturing cost of the glass, the Yb2O3 content is preferably within the above range.

[0312] In the case of glass composition B, the glass material for molding according to this embodiment is preferably composed mainly of the above-mentioned glass components SiO2, B2O3, Al2O3, P2O5, Li2O, Na2O, K2O, Cs2O, MgO, CaO, SrO, BaO, ZnO, La2O3, Gd2O3, Y2O3, ZrO2, TiO2, Nb2O5, WO3, Bi2O3, Ta2O5, Sc2O3, HfO2, Lu2O3, GeO2, and Yb2O3, and the total content of the above-mentioned glass components is preferably 95% or more, more preferably 98% or more, even more preferably 99% or more, and even more preferably 99.5% or more.

[0313] In the glass material for molding according to this embodiment, the upper limit of the TeO2 content is preferably 2%, and the lower limit of the TeO2 content is preferably 0%.

[0314] Since TeO2 is toxic, it is preferable to reduce the content of TeO2, and therefore the content of TeO2 is preferably within the above range.

[0315] In the glass material for molding according to this embodiment, in the case of glass composition B, the fluorine (F) content is preferably 3% or less, with the upper limit being 1%, 0.5%, and 0.3%, in that order. The lower the F content, the more preferable, and the lower limit is preferably 0%. The F content may be 0%. Preferably, the glass is substantially free of fluorine (F).

[0316] In glass composition B, by setting the F content within the above range, volatilization during melting of the glass can be suppressed, and fluctuations in the refractive index and striae can be suppressed.

[0317] It is preferable that the glass material for molding according to this embodiment is basically composed of the above glass components, but it may contain other components as long as they do not impair the effects of the present invention. Furthermore, the present invention does not exclude the inclusion of unavoidable impurities.

[0318] <Other ingredient composition> Pb, As, Cd, Tl, Be, and Se are all toxic, so it is preferable that the glass material for molding according to this embodiment does not contain these elements as glass components.

[0319] U, Th, and Ra are all radioactive elements, and therefore it is preferable that the glass material for molding according to this embodiment does not contain these elements as glass components.

[0320] V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, and Tm increase the coloration of the glass and can be sources of fluorescence, so it is preferable that the glass material for molding according to this embodiment does not contain these elements as glass components.

[0321] Sb (Sb2O3) and Ce (CeO2) are elements that can be added as fining agents. Of these, Sb (Sb2O3) is a fining agent with a large fining effect.

[0322] The content of Sb2O3 is expressed as an exclusive percentage. When the total content of all glass components is taken as 100% by mass, the Sb2O3 content is preferably less than 1% by mass, more preferably less than 0.1% by mass. Furthermore, less than 0.05% by mass, less than 0.03% by mass, less than 0.02% by mass, and less than 0.01% by mass are more preferable in this order. The Sb2O3 content may be 0% by mass.

[0323] The CeO2 content is also expressed as an exclusive percentage. That is, when the total content of all glass components other than CeO2 and Sb2O3 is taken as 100 mass%, the CeO2 content is preferably less than 2 mass%, more preferably less than 1 mass%, even more preferably less than 0.5 mass%, and even more preferably less than 0.1 mass%. The CeO2 content may be 0 mass%. By keeping the CeO2 content within the above range, the clarity of the glass can be improved.

[0324] (Glass properties when glass composition B is included) <Refractive index nd> In the glass material for molding according to this embodiment, in the case of glass composition B, the refractive index nd is not particularly limited and can be, for example, 1.60 to 2.10, preferably 1.65 to 2.00, more preferably 1.70 to 1.88, and even more preferably 1.73 to 1.85. The lower limit of the refractive index nd may be 1.65, 1.74, 1.75, 1.76, 1.77, 1.78, or 1.79, and the upper limit of the refractive index nd may be 2.0, 1.9, 1.84, 1.83, or 1.82.

[0325] The refractive index nd can be adjusted to a desired value by appropriately adjusting the content of each glass component in the glass composition B. The component that functions to relatively increase the refractive index nd (the component that increases the refractive index) is Nb 5+ , Ti 4+ , W 6+ , Bi 3+ , Ta 5+ , Zr 4+ , La 3+3 etc. (i.e., in oxide representation, Nb2O5, TiO2, WO3, Bi2O3, Ta2O5, ZrO2, La2O3 etc.). On the other hand, the components that act to relatively lower the refractive index nd (refractive index lowering components) are P 5+ , Si 4+ , B 3+ , Li + , Na + , K. + etc. (In other words, in oxide notation, P2O5, SiO2, B2O3, Li2O, Na2O, K2O, etc.) is.

[0326] <Abbe number νd> In the glass material for molding according to this embodiment, when glass composition B is used, the Abbe number vd can exhibit an Abbe number of 20 to 70, preferably 25 to 65, more preferably 30 to 60, and even more preferably 35 to 55. The lower limit of the Abbe number vd may be 23, 28, 32, 36, 37, 38, 39, or 40, and the upper limit of the Abbe number vd may be 67, 63, 57, 53, 51, 49, 47, 45, 43, or 42.

[0327] The Abbe number νd can be adjusted to a desired value by appropriately adjusting the content of each glass component in the glass composition B. The component that relatively lowers the Abbe number νd, i.e., the high dispersion component, is Nb 5+ , Ti 4+ , W 6+ , Bi 3+ , Ta 5+ , Zr 4+ etc. (In other words, in oxide representation, Nb2O5, TiO2, WO3, Bi2O3, Ta2O5, ZrO2, etc.) On the other hand, the components that relatively increase the Abbe number νd, that is, the low dispersion components, are P 5+ , Si 4+ , B 3+ , Li + , Na + , K. + , La 3+ , Ba 2+ , Ca 2+ , Sr 2+etc. (i.e., in oxide terms, P2O5, SiO2, B2O3, Li2O, Na2O, K2O, La2O3, BaO, CaO, SrO, etc.).

[0328] In the glass material for molding according to this embodiment, in the case of glass composition B, the refractive index nd and Abbe number vd preferably satisfy the following formula (1), more preferably satisfy the following formula (2), even more preferably satisfy the following formula (3), and particularly preferably satisfy the following formula (4): When the refractive index nd and Abbe number vd satisfy the following formula, a glass material for molding having high refractive index and low dispersion properties can be obtained. nd-(-0.0183 × Abbe number νd+2.502)≧0 …(1) nd-(-0.0183 × Abbe number νd+2.512)≧0 …(2) nd-(-0.0183 × Abbe number νd+2.522)≧0 …(3) nd-(-0.0183 × Abbe number νd+2.532)≧0 …(4)

[0329] <Average linear expansion coefficient α L > In the glass material for molding according to this embodiment, in the case of glass composition B, the average linear expansion coefficient α L The lower limit of is preferably 0.80 × 10 -5 °C -1 and 0.81×10 -5 °C -1 , 0.82×10 -5 °C -1 , 0.83×10 -5 °C -1 , 0.84×10 -5 °C -1 , 0.85×10 -5 °C -1 , 0.86×10 -5 °C -1 , 0.87×10 -5 °C -1 , 0.88×10 -5 °C -1 In addition, the average linear expansion coefficient α L The upper limit of 1.20×10 is set to maintain the stability of the glass and obtain the desired optical properties.-5 °C -1 can be exemplified, and preferably 1.10 × 10 -5 °C -1 is less than or equal to 1.00 x 10 -5 °C -1 , 0.98×10 -5 °C -1 , 0.96×10 -5 °C -1 , 0.95×10 -5 °C -1 , 0.94×10 -5 °C -1 , 0.93×10 -5 °C -1 The order of preference is:

[0330] In the case of glass composition B, the average linear expansion coefficient α at -30 to 70°C L By setting the temperature within the above range, it is possible to obtain a glass material for molding that can be used in a wide range of temperature environments.

[0331] Average linear expansion coefficient α L The average linear expansion coefficient α is measured in accordance with the provisions of JOGIS16. The sample is a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm. With a load of 98 mN applied to the sample, it is heated at a constant rate of 4°C per minute, and the temperature and the elongation of the sample are measured in 1-second intervals. L is the average value of the linear expansion coefficient at -30 to 70°C.

[0332] In addition, in JOGIS16, "the average linear expansion coefficient is 10 -7 °C -1 However, in this specification, the average linear expansion coefficient α L is [10 -5 °C -1 ] is displayed as a unit.

[0333] In this specification, the average linear expansion coefficient α L Regarding [10 -5 °C -1 ], but the unit is [10 -5 ·K -1Even when using the average linear expansion coefficient α L The numerical values ​​are the same.

[0334] <Average linear expansion coefficient α 100-300 > In the glass material for molding according to this embodiment, in the case of glass composition B, the average linear expansion coefficient α 100-300 The lower limit of the average linear expansion coefficient α is preferably 90, and more preferably 92, 94, and 95 in that order. 100-300 From the viewpoint of maintaining the stability of the glass and obtaining the desired optical properties, the upper limit of the glass viscosity can be 130, preferably 115, with 110, 106 and 104 being more preferred in that order.

[0335] Average linear expansion coefficient α 100-300 The average linear expansion coefficient α is measured in accordance with the JOGIS08 standard. The sample is a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm. With a load of 98 mN applied to the sample, it is heated at a constant rate of 4°C per minute, and the temperature and the elongation of the sample are measured every second. 100-300 is the average value of the linear expansion coefficient at 100 to 300°C.

[0336] In this specification, the average linear expansion coefficient α 100-300 In accordance with the provisions of JOGIS08, -7 °C -1 In other words, the average linear expansion coefficient α 100-300 is [10 -7 °C -1 ] is displayed as an integer in units of .

[0337] <Temperature coefficient of relative refractive index dn / dT> The temperature coefficient of the relative refractive index of glass (dn / dT) is measured according to Japanese Industrial Standard JIS B7072-2 (Method for measuring the temperature coefficient of refractive index of optical glass - Part 2: Interferometry) for light with a wavelength of 632.8 nm when the temperature is changed from -40°C to 110°C. In this specification, the temperature coefficient of the relative refractive index (dn / dT) is defined as [10-6 °C -1 ], but the unit is [10 -6 ·K -1 ], the value of the temperature coefficient of the relative refractive index dn / dT remains the same.

[0338] In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the temperature coefficient of the relative refractive index dn / dT is preferably 2.0 × 10 at the wavelength of the He—Ne laser (633 nm to 632.8 nm) and in the temperature range of 20 to 40° C. -6 °C -1 and even 1.5 × 10 -6 °C -1 , 1.0×10 -6 °C -1 , 0.5×10 -6 °C -1 , 0.0×10 -6 °C -1 , -0.5×10 -6 °C -1 , -1.0×10 -6 °C -1 Although there is no clear lower limit to the temperature coefficient of the relative refractive index dn / dT, it is preferably −13.0×10 in the wavelength of a He—Ne laser (633 nm to 632.8 nm) and in the temperature range of 20 to 40° C. -6 °C -1 and even -10.0×10 -6 °C -1 , -9.0×10 -6 °C -1 , -8.0×10 -6 °C -1 , -7.0×10 -6 °C -1 , -6.5×10 -6 °C -1 The order of preference is:

[0339] By setting dn / dT within the above range and combining it with an optical element in which dn / dT is a positive value, or an optical element in which dn / dT is a negative value and the lens focal length has a different sign, the fluctuations in the refractive index are reduced even in an environment in which the temperature of the optical element fluctuates greatly, and it is possible to exhibit the desired optical characteristics with high precision over a wider temperature range.

[0340] On the other hand, when high-energy light, such as laser light or light with a wavelength equivalent to that absorbed by glass, is incident on the glass, the extent of the temperature rise of the glass varies depending on the intensity of the light and the irradiation time. In this case, it may be required to reduce the temperature change of the refractive index of the glass of this embodiment alone.

[0341] In such a case, the upper limit of the temperature coefficient of the relative refractive index dn / dT is preferably 2.0×10 -6 °C -1 and even 1.5 × 10 -6 °C -1 , 1.0×10 -6 °C -1 , 0.5×10 -6 °C -1 , 0.3×10 -6 °C -1 , 0.1×10 -6 °C -1 The lower limit of the temperature coefficient of the relative refractive index dn / dT is preferably −2.0×10 -6 °C -1 and even -1.5×10 -6 °C -1 , -1.0×10 -6 °C -1 , -0.5×10 -6 °C -1 , -0.3 × 10 -6 °C -1 , -0.1×10 -6 °C -1 The temperature coefficient of the relative refractive index dn / dT is 0.0×10 -6 °C -1 The value of the temperature coefficient of relative refractive index (dn / dT) of the glass material for molding according to this embodiment may be appropriately selected within the above-mentioned preferred range depending on the laser wavelength to be used, taking into consideration the description in this specification.

[0342] <Method for measuring the temperature dependence of the temperature coefficient of relative refractive index dn / dT> The glass of this embodiment has a small temperature dependency of the temperature coefficient of relative refractive index (dn / dT) in the case of glass composition B. The measurement method is as follows.

[0343] Measurement is performed using the interference method, one of the methods described in the Japan Optical Glass Industry Association Standard JOGIS18, "Method for measuring the temperature coefficient of refractive index of optical glass." The temperature is changed from -40°C to 80°C, and dn / dT at a wavelength of 632.8 nm (hereinafter referred to as dn / dT@632.8) is measured at temperatures of -30°C, -10°C, +10°C, +30°C, +50°C, and +70°C. An approximation line for the dn / dT@632.8 values ​​versus temperature is obtained using the least squares method, and the slope of the line is defined as a, and the intercept at a temperature of 0°C is defined as b.

[0344] The closer the slope a is to 0, the smaller the amount of change in dn / dT due to temperature, which means that the change in the value of dn / dT per temperature change is smaller even in different temperature ranges. In other words, because the shift in focal length per unit temperature change of the optical element is constant regardless of temperature, the position adjustment mechanism on the light receiving element side can be simplified, which is effective for optical elements that require high-precision imaging.

[0345] Therefore, in the glass material for molding according to this embodiment, in the case of glass composition B, the range of the value of the slope a is preferably 10.0×10 -9 ~-10.0×10 -9 and 8.0×10 -9 ~-8.0×10 -9 , 6.0×10 -9 ~-6.0×10 -9 , 4.0×10 -9 ~-4.0×10 -9 , 3.0×10 -9 ~-3.0×10 -9 The order of preference is:

[0346] Also, the intercept b above is 0.0×10 -6The closer it is to this, the smaller the value of dn / dT@632.8 at 0°C on the approximation line is, which means that the absolute value of dn / dT is smaller. Therefore, the amount of focal length shift per unit temperature change of a single optical element is small, making it effective for optical elements that require high-precision imaging.

[0347] Therefore, in the glass material for molding according to this embodiment, in the case of glass composition B, the range of the value of the intercept b is preferably 3.0 × 10 -6 ~-3.0×10 -6 and even 2.0×10 -6 ~-2.0×10 -6 , 1.0×10 -6 ~-1.0×10 -6 , 0.5×10 -6 ~-0.5×10 -6 The intercept b does not necessarily have to be 0, provided that the value of the slope a is controlled to a certain value or less, preferably close to 0. The intercept b can also be set close to 0.

[0348] <Glass transition temperature Tg> In the glass material for molding according to this embodiment, in the case of glass composition B, the upper limit of the glass transition temperature Tg is preferably 730°C, and more preferably 720°C, 710°C, and 700°C in that order. The lower limit of the glass transition temperature Tg is preferably 500°C, and more preferably 550°C, 560°C, 570°C, and 580°C in that order.

[0349] By ensuring that the upper limit of the glass transition temperature Tg satisfies the above range, increases in the molding temperature and annealing temperature of the glass can be suppressed, thereby reducing thermal damage to press molding equipment and annealing equipment. Furthermore, by ensuring that the lower limit of the glass transition temperature Tg satisfies the above range, it becomes easier to maintain the desired Abbe number and refractive index while maintaining good thermal stability of the glass. Furthermore, good moldability can be obtained when used as a precision press material.

[0350] On the other hand, the higher the glass transition temperature Tg, the smaller the amount of expansion per unit temperature change, which tends to reduce the degree of shape change due to thermal expansion per unit temperature change. Also, if the temperature of the glass rises to near Tg or above the strain point by heating, there is a risk that the optical performance will not return to its original state even if the glass is subsequently cooled. Therefore, it is preferable that the lower limit of Tg be within the above range.

[0351] <Specific gravity of glass> In the glass material for molding according to this embodiment, when the glass has composition B, the specific gravity is preferably 5.50 or less, with 5.00 or less and 4.80 or less being more preferable. If the specific gravity of the glass can be reduced, the weight of the lens can be reduced. As a result, the power consumption of the autofocus drive of the camera lens in which the lens is mounted can be reduced.

[0352] <Light transmittance of glass> The light transmittance of the glass material for molding according to this embodiment can be evaluated by the coloring degrees λ5, λ70, and λ80. For glass composition B, the spectral transmittance is measured in the wavelength range of 200 to 700 nm for a glass sample with a thickness of 10.0 mm ± 0.1 mm, and the wavelength at which the external transmittance is 5% is defined as λ5, the wavelength at which the external transmittance is 70% is defined as λ70, and the wavelength at which the external transmittance is 80% is defined as λ80.

[0353] In the glass material for molding according to this embodiment, in the case of glass composition B, λ5 is preferably 400 nm or less, more preferably 380 nm or less, even more preferably 360 nm or less, and particularly preferably 350 nm or less.

[0354] In the glass material for molding according to this embodiment, in the case of glass composition B, λ70 is preferably 440 nm or less, more preferably 430 nm or less, and even more preferably 420 nm or less.

[0355] In the glass material for molding according to this embodiment, in the case of glass composition B, λ80 is preferably 510 nm or less, more preferably 500 nm or less, and even more preferably 490 nm or less.

[0356] By using a molding glass material in which λ5, λ70, and λ80 have been shortened as described above, it is possible to provide an optical element that allows for suitable color reproduction.

[0357] (Glass composition C) Next, when the glass material for molding according to this embodiment has glass composition C, the contents and ratios of the glass components and the glass properties will be described.

[0358] In the glass material for molding according to this embodiment, in the case of glass composition C, SiO2 is an essential component that functions as a glass network-forming component to improve the thermal stability, reheat devitrification resistance, chemical durability, and weather resistance of the glass, increase the viscosity of the glass melt, and make the glass melt easier to mold. From the above perspectives, the SiO2 content, expressed in mass%, is preferably greater than the total content of B2O3 and P2O5. In the case of glass composition C, a silicate glass is preferred. In the case of glass composition C, the SiO2 content is preferably 8.0% or more, and more preferably in this order: 10.00% or more, 11.00% or more, 12.00% or more, 13.00% or more, 14.00% or more, 14.50% or more, 15.00% or more, 15.50% or more, 16.00% or more, 16.50% or more, and 16.60% or more. In the glass material for molding according to this embodiment, in the case of glass composition C, from the viewpoint of improving the devitrification resistance, meltability, and partial dispersion characteristics of the glass, the SiO content is preferably 50.00% or less, and is more preferably 45.00% or less, 40.00% or less, 35.00% or less, 30.00% or less, 28.00% or less, 26.00% or less, 25.00% or less, 24.50% or less, 24.00% or less, 23.50% or less, 23.00% or less, 22.75% or less, 22.50% or less, and 22.00% or less in that order.

[0359] In the glass material for molding according to this embodiment, in the case of glass composition C, the total content of SiO2 and B2O3 (SiO2 + B2O3) is preferably 10.00% or more, and more preferably 12.00% or more, 14.00% or more, 15.00% or more, 16.00% or more, 17.00% or more, 17.75% or more, from the viewpoint of improving the thermal stability of the glass, further lowering the specific gravity, and obtaining more desirable optical constants. It is preferably 18.00% or more, 18.25% or more, 18.50% or more, and 18.60% or more in that order, and is preferably 35.00% or less, and more preferably 32.00% or less, 30.00% or less, 28.00% or less, 27.00% or less, 26.50% or less, 26.00% or less, 25.50% or less, 25.00% or less, 24.50% or less, 24.40% or less, and 24.30% or less in that order.

[0360] In the glass material for molding according to this embodiment, in the case of glass composition C, SiO2 and B2O3 function to improve the thermal stability of the glass, but as the SiO2 content increases, the meltability of the glass tends to decrease. From the above perspectives, the mass ratio of SiO2 to the total content of SiO2 and B2O3 (SiO2 / (SiO2+B2O3)) is preferably 0.50 or more, and more preferably 0.55 or more, 0.60 or more, 0.65 or more, 0.70 or more, 0.75 or more, 0.77 or more, and 0.80 or more, and is preferably 1.00 or less, and more preferably 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.89 or less, and 0.88 or less, in that order.

[0361] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the B2O3 content to the SiO2 content (B2O3 / SiO2) is maxFrom the viewpoint of reducing the mass ratio (B2O3 / SiO2) and improving reheat devitrification resistance, the mass ratio (B2O3 / SiO2) is preferably less than 1.00, and more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.35 or less, 0.32 or less, 0.31 or less, 0.30 or less, 0.29 or less, 0.28 or less, 0.27 or less, 0.26 or less, and 0.25 or less in this order. From the viewpoint of improving thermal stability, the mass ratio (B2O3 / SiO2) is preferably 0.00 or more, and more preferably 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, and 0.15 or more in this order.

[0362] In the glass material for molding according to this embodiment, in the case of glass composition C, the B2O3 content is preferably 0.00% or more, more preferably more than 0.00%, and more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.35% or more, 0.37% or more, 0.39% or more, 0.40% or more, 0.41% or more, 0.42% or more, 0.43% or more, 0.44% or more, 0.45% or more, 0.46% or more, 0.47% or more, 0.48% or more, and 0.49% or more, in that order. The B2O3 content is preferably 30.00% or less, and is more preferably 25.00% or less, 20.00% or less, 18.00% or less, 16.00% or less, 14.00% or less, 12.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.50% or less, 5.20% or less, 5.10% or less, 5.00% or less, 4.90% or less, and 4.80% or less, in that order. By keeping the B2O3 content within the above range, the specific gravity of the glass can be further reduced and the thermal stability of the glass can be improved.

[0363] In the glass material for molding according to this embodiment, in the case of glass composition C, the CaO content is preferably 3.00% or more, more preferably 4.00% or more, from the viewpoint of improving the meltability and thermal stability of the glass, and more preferably 5.00% or more, 5.10% or more, 5.20% or more, 5.30% or more, 5.40% or more, 5.50% or more, 5.60% or more, 5.70% or more, 5.80% or more, and 5.90% or more in this order. From the same viewpoint, the CaO content is preferably 40.00% or less, and more preferably 35.00% or less, 30.00% or less, 28.00% or less, 26.00% or less, 24.00% or less, 22.00% or less, 21.50% or less, 21.00% or less, 20.50% or less, 20.25% or less, 20.00% or less, and 19.50% or less in this order.

[0364] In the glass material for molding according to the present embodiment, in the case of glass composition C, the total content of the alkaline earth metal oxides MgO, CaO, SrO, and BaO and ZnO (MgO+CaO+SrO+BaO+ZnO) is preferably 5.00% or more, and more preferably in the following order: 7.00% or more, 10.00% or more, 11.00% or more, 12.00% or more, 13.00% or more, 13.50% or more, 14.00% or more, 14.50% or more, 15.00% or more, 15.30% or more, 15.50% or more, and 16.00% or more. The total content (MgO+CaO+SrO+BaO+ZnO) is preferably 50.00% or less, and more preferably 45.00% or less, 40.00% or less, 39.00% or less, 38.00% or less, 37.00% or less, 36.50% or less, 36.00% or less, 35.50% or less, 35.00% or less, 34.50% or less, and 34.00% or less in that order. The total content (MgO+CaO+SrO+BaO+ZnO) within the above range is preferred from the viewpoint of maintaining thermal stability without interfering with further lowering the specific gravity and high dispersion.

[0365] In the glass material for molding according to this embodiment, in the case of glass composition C, among MgO, CaO, SrO, BaO, and ZnO, MgO and CaO are more effective components in suppressing the specific gravity of the glass than SrO, BaO, and ZnO. Therefore, from the viewpoint of further suppressing an increase in specific gravity, the mass ratio of the total content of ZnO, SrO, and BaO to the total content of MgO and CaO ((ZnO+SrO+BaO) / (MgO+CaO)) is preferably 2.78 or less, and more preferably 2.77 or less, 2.76 or less, 2.75 or less, 2.74 or less, and 2.73 or less in that order. On the other hand, SrO, BaO, and ZnO work to improve partial dispersion characteristics more effectively than MgO and CaO. Therefore, from the viewpoint of improving partial dispersion characteristics, the mass ratio ((ZnO+SrO+BaO) / (MgO+CaO)) is preferably 0.17 or more, and more preferably 0.18 or more, 0.19 or more, and 0.20 or more in that order.

[0366] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the CaO content to the total content of MgO, CaO, SrO, BaO, and ZnO (CaO / (MgO+CaO+SrO+BaO+ZnO)) is preferably 0.35 or more, in order of increasing the refractive index and decreasing the specific gravity, and more preferably 0.36 or more, 0.37 or more, 0.38 or more, 0.39 or more, 0.40 or more, 0.41 or more, and 0.42 or more. From the viewpoint of improving thermal stability, the mass ratio (CaO / (MgO+CaO+SrO+BaO+ZnO)) is preferably 1.00 or less, and more preferably 0.95 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less, 0.86 or less, 0.85 or less, 0.84 or less, 0.83 or less, 0.80 or less, and 0.78 or less.

[0367] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the total content of CaO and MgO to the total content of MgO, CaO, SrO, BaO, and ZnO ((CaO+MgO) / (MgO+CaO+SrO+BaO+ZnO)) is preferably 0.35 or more, from the viewpoint of further reducing the specific gravity, and is more preferably 0.36 or more, 0.37 or more, 0.38 or more, 0.39 or more, 0.40 or more, 0.41 or more, and 0.42 or more in that order. From the viewpoint of improving thermal stability, the mass ratio ((CaO+MgO) / (MgO+CaO+SrO+BaO+ZnO) is preferably 1.00 or less, and more preferably 0.95 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less, 0.86 or less, 0.85 or less, 0.84 or less, 0.83 or less, 0.80 or less, and 0.78 or less in that order.

[0368] In the glass composition C of the molding glass material according to this embodiment, the alkaline earth metal oxides MgO, CaO, SrO, BaO, and ZnO lower the liquidus temperature and improve thermal stability. On the other hand, increasing their content tends to decrease chemical durability and / or weather resistance. Furthermore, SiO2 and BO3 improve thermal stability and reheat devitrification, but increasing their content tends to decrease meltability. From the above viewpoints, the mass ratio of the total content of SiO2 and B2O3 to the total content of MgO, CaO, SrO, BaO, and ZnO ((SiO2 + B2O3) / (MgO + CaO + SrO + BaO + ZnO)) is preferably 0.40 or more, and more preferably 0.45 or more, 0.50 or more, 0.52 or more, 0.54 or more, 0.56 or more, 0.57 or more, 0.58 or more, 0.59 or more, 0.60 or more, 0.61 or more, 0.70 or more, 0.80 or more, 0.90 or more, 1.00 or more, and 1.10 or more in that order; it is preferably 2.00 or less, and more preferably 1.80 or less, 1.60 or less, 1.55 or less, 1.50 or less, 1.45 or less, 1.40 or less, and 1.35 or less in that order.

[0369] In the glass material for molding according to this embodiment, in the case of glass composition C, the MgO content is preferably 0.00% or more. The MgO content is preferably 15.00% or less, and more preferably 12.00% or less, 9.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.50% or less, 3.00% or less, 2.50% or less, and 2.10% or less, in that order.

[0370] In the glass material for molding according to this embodiment, in the case of glass composition C, the SrO content is preferably 0.00% or more, and more preferably 0.10% or more, 0.20% or more, 0.25% or more, 0.26% or more, 0.27% or more, 0.28% or more, 0.29% or more, 0.30% or more, and 0.31% or more in that order. Also, the SrO content is preferably 15.00% or less, and more preferably 12.00% or less, 10.00% or less, 9.00% or less, 8.50% or less, 8.00% or less, 7.50% or less, 7.00% or less, 6.50% or less, and 6.00% or less in that order.

[0371] In the glass material for molding according to this embodiment, in the case of glass composition C, the BaO content is preferably 0.00% or more, and more preferably 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, 0.50% or more, 0.60% or more, 0.70% or more, 0.80% or more, 0.90% or more, 1.00% or more, 1.10% or more, 1.20% or more, and 1.30% or more in this order. Also, the BaO content is preferably 25.00% or less, and more preferably 22.00% or less, 20.00% or less, 19.00% or less, 18.00% or less, 17.00% or less, 16.50% or less, 16.00% or less, 15.50% or less, 15.25% or less, and 15.00% or less in this order.

[0372] MgO, CaO, SrO, and BaO are glass components that improve the thermal stability and devitrification resistance of the glass. From the viewpoints of high dispersibility and further reducing the specific gravity, and improving the thermal stability and devitrification resistance of the glass, the contents of these glass components are preferably within the above-mentioned ranges.

[0373] In the glass material for molding according to this embodiment, in the case of glass composition C, the ZnO content is preferably 0.00% or more. Furthermore, the ZnO content is preferably 10.00% or less, and more preferably 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, and 2.00% or less, in that order. ZnO is a glass component that functions to improve the thermal stability of the glass. From the viewpoints of further reducing the specific gravity, improving the thermal stability of the glass, and obtaining more desirable optical constants, the ZnO content is preferably within the above range.

[0374] In the glass material for molding according to this embodiment, in the case of glass composition C, the total content of the rare earth oxides La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is preferably more than 0% from the viewpoint of achieving a high refractive index and low dispersion, and more preferably 0.50% or more, 1.00% or more, 1.33% or more, 1.50% or more, 2.00% or more, 2.50% or more, and 3.00% or more in that order. From the viewpoint of further reducing the specific gravity, the total content of La2O3, Gd2O3, and Y2O3 (La2O3 + Gd2O3 + Y2O3) is preferably 30.00% or less, and more preferably 29.00% or less, 28.00% or less, 26.00% or less, 24.00% or less, 22.00% or less, 20.00% or less, 18.00% or less, 16.00% or less, 15.00% or less, 14.50% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.50% or less, and 12.00% or less in that order.

[0375] In the glass material for molding according to this embodiment, in the case of glass composition C, BaO and the rare earth oxides La2O3, Gd2O3, and Y2O3 are all components that contribute to low dispersion (i.e., increase the Abbe number vd), but increasing their contents tends to increase the specific gravity of the glass. From the above perspective, in the case of glass composition C, the total content of BaO and the rare earth oxides La2O3, Gd2O3, and Y2O3 (BaO + La2O3 + Gd2O3 + Y2O3) is preferably 30.00% or less, and more preferably 29.00% or less, 28.00% or less, 27.00% or less, 26.00% or less, 25.00% or less, 24.50% or less, 24.00% or less, 23.50% or less, and 23.00% or less, in that order. Furthermore, from the viewpoint of increasing the Abbe number vd, the total content of BaO, La2O3, Gd2O3, and Y2O3 (BaO + La2O3 + Gd2O3 + Y2O3) is preferably more than 0%, and more preferably 1.00% or more, 2.00% or more, 3.00% or more, 4.00% or more, 5.00% or more, 6.00% or more, 7.00% or more, 7.50% or more, 8.00% or more, and 8.50% or more, in that order.

[0376] In the glass material for molding according to this embodiment, in the case of glass composition C, both BaO and La2O3 are low-dispersion components, but BaO has a smaller effect of increasing the refractive index than La2O3. Therefore, from the viewpoint of increasing the refractive index, the mass ratio of the BaO content to the La2O3 content (BaO / La2O3) is preferably 8.30 or less, and is more preferably 8.00 or less, 7.50 or less, 7.00 or less, 6.50 or less, 6.00 or less, 5.50 or less, 5.40 or less, 5.30 or less, 5.20 or less, 5.10 or less, 5.00 or less, 4.90 or less, 4.80 or less, and 4.70 or less in that order. In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio (BaO / La2O3) may be 0 or 0.00 or more. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio (BaO / La2O3) is preferably more than 0.00, and is more preferably 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, and 0.11 or more in that order.

[0377] In the glass composition C of the molding glass material according to this embodiment, the rare earth oxides La2O3, Gd2O3, and YO3 can increase the refractive index and contribute to low dispersion, but increasing their content tends to decrease thermal stability. Also, SiO2 and BO3 function to improve thermal stability, but increasing their content tends to decrease meltability and the refractive index. From the above viewpoints, the mass ratio of the total content of SiO2 and B2O3 to the total content of La2O3, Gd2O3, and Y2O3 ((SiO2+B2O3) / (La2O3+Gd2O3+Y2O3)) is preferably more than 0.00, and is more preferably 0.25 or more, 0.50 or more, 0.75 or more, 1.00 or more, 1.25 or more, 1.50 or more, 1.75 or more, 1.80 or more, and 1.85 or more, in that order; it is preferably 7.47 or less, and is more preferably 7.40 or less, 7.35 or less, 7.30 or less, and 7.25 or less, in that order.

[0378] In the glass material for molding according to this embodiment, in the case of glass composition C, La2O3, Gd2O3, and Y2O3 are all components that can increase the refractive index of the glass, but Gd2O3 and Y2O3 are components that increase the specific gravity compared to La2O3. Therefore, from the viewpoint of further reducing the specific gravity, the mass ratio of the La2O3 content to the total content of La2O3, Gd2O3, and Y2O3 (La2O3 / (La2O3+Gd2O3+Y2O3)) is preferably greater than 0.00, and more preferably 0.10 or more, 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, and 0.75 or more in that order. The mass ratio (La2O3 / (La2O3+Gd2O3+Y2O3)) can be 1.00 or less. From the same viewpoint, in the case of glass composition C, the mass ratio of the Gd2O3 content to the total content of La2O3, Gd2O3, and Y2O3 (Gd2O3 / (La2O3+Gd2O3+Y2O3)) is preferably less than 1.00, and is more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less, 0.25 or less, and 0.20 or less, in that order. The mass ratio (Gd2O3 / (La2O3+Gd2O3+Y2O3)) can be 0.00 or more. From the same viewpoint, in the case of glass composition C, the mass ratio of the Y2O3 content to the total content of La2O3, Gd2O3, and Y2O3 (Y2O3 / (La2O3+Gd2O3+Y2O3)) is preferably less than 1.00, and is more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less, and 0.25 or less, in that order. The mass ratio (Y2O3 / (La2O3+Gd2O3+Y2O3)) can be 0.00 or more.

[0379] In the glass material for molding according to this embodiment, in the case of glass composition C, from the above viewpoint, the contents of the above components which are rare earth oxides are preferably in the following ranges. The La2O3 content is preferably 0.00% or more, and more preferably in the order of over 0.00%, 0.50% or more, 1.00% or more, 1.33% or more, 1.50% or more, 2.00% or more, 2.50% or more, 2.75% or more, and 3.00% or more. The La2O3 content is preferably 30.00% or less, and more preferably in the order of 25.00% or less, 20.00% or less, 18.00% or less, 16.00% or less, 15.00% or less, 14.00% or less, 13.50% or less, 13.00% or less, 12.50% or less, and 12.00% or less. The Gd2O3 content is preferably 0.00% or more. The Gd2O3 content is preferably 10.00% or less, and more preferably 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, and 2.00% or less in that order. The Y2O3 content is preferably 0.00% or more. The Y2O3 content is preferably 10.00% or less, and more preferably 9.00% or less, 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, and 2.00% or less in that order.

[0380] In the glass material for molding according to this embodiment, in the case of glass composition C, La2O3 functions to increase the refractive index of the glass, while B2O3 tends to decrease the refractive index of the glass. Therefore, from the viewpoint of achieving a higher refractive index, the mass ratio of the La2O3 content to the B2O3 content (La2O3 / B2O3) is preferably 1.30 or more, and more preferably 1.35 or more, 1.40 or more, 1.45 or more, 1.50 or more, 1.55 or more, 1.60 or more, 1.65 or more, 1.70 or more, and 1.72 or more in this order. From the viewpoint of achieving a lower specific gravity, the mass ratio (La2O3 / B2O3) is preferably 20.00 or less, and more preferably 18.00 or less, 16.00 or less, 14.00 or less, 13.00 or less, 12.00 or less, 11.50 or less, 11.00 or less, 10.50 or less, and 10.00 or less in this order.

[0381] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the B2O3 content to the La2O3 content (B2O3 / La2O3) is preferably 0.79 or less, and more preferably 0.78 or less, 0.77 or less, 0.76 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.64 or less, 0.62 or less, 0.61 or less, 0.60 or less, 0.59 or less, 0.58 or less, 0.57 or less, and 0.50 or less in that order. The mass ratio (La2O3 / B2O3) is preferably 0.00 or more, and more preferably greater than 0.00.

[0382] In the glass material for molding according to this embodiment, in the case of glass composition C, rare earth oxides can increase the refractive index of the glass, but increasing the content of rare earth oxides tends to decrease the thermal stability and meltability of the glass. Therefore, from the viewpoint of further increasing the refractive index while maintaining the thermal stability of the glass, the mass ratio of the total content of La2O3, Gd2O3, and Y2O3 to the total content of BaO, La2O3, Gd2O3, and Y2O3 ((La2O3 + Gd2O3 + Y2O3) / (BaO + La2O3 + Gd2O3 + Y2O3)) is preferably 1.00 or less, and is more preferably less than 1.00, 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, and 0.90 or less in that order. The mass ratio ((La2O3+Gd2O3+Y2O3) / (BaO+La2O3+Gd2O3+Y2O3)) is preferably greater than 0.00, and is more preferably 0.05 or greater, 0.06 or greater, 0.07 or greater, 0.08 or greater, 0.09 or greater, 0.10 or greater, 0.11 or greater, 0.12 or greater, 0.13 or greater, 0.14 or greater, 0.15 or greater, 0.16 or greater, 0.17 or greater, 0.18 or greater, and 0.20 or greater, in that order.

[0383] In the glass material for molding according to this embodiment, in the case of glass composition C, rare earth oxides can increase the refractive index of the glass, but increasing their content tends to decrease the meltability of the glass. On the other hand, alkaline earth metal oxides can increase the meltability of the glass, but increasing their content tends to decrease the refractive index. Therefore, in order to further increase the refractive index while maintaining the meltability of the glass, the mass ratio of the total content of La2O3, Gd2O3, and Y2O3 to the total content of MgO, CaO, SrO, BaO, ZnO, La2O3, Gd2O3, and Y2O3 ((La2O3+Gd2O3+Y2O3) / (MgO+CaO+SrO+BaO+ZnO+La2O3+Gd2O3+Y2O3)) is preferably greater than 0.00. It is preferably 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more in that order, and is preferably 0.85 or less, and more preferably 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.44 or less, 0.43 or less, 0.42 or less, 0.41 or less, 0.40 or less in that order.

[0384] In the glass material for molding according to this embodiment, in the case of glass composition C, rare earth oxides can increase the refractive index of the glass, but increasing their content tends to decrease the thermal stability of the glass. On the other hand, B2O3 can increase the thermal stability of the glass, but increasing their content tends to decrease the refractive index. Therefore, to further increase the refractive index while maintaining the thermal stability of the glass, the mass ratio of the B2O3 content to the total content of BaO, La2O3, Gd2O3, and YO3 (B2O3 / (BaO+La2O3+Gd2O3+YO3)) is preferably 0.00 or more, more preferably greater than 0.00, 0.01 or more, 0.02 or more, and 0.03 or more, in that order. It is preferably 1.00 or less, and even more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, and 0.35 or less.

[0385] In the glass material for molding according to this embodiment, in the case of glass composition C, La2O3, Gd2O3, and Y2O3 function to increase the refractive index of the glass, but a high total content of these elements tends to decrease the thermal stability. On the other hand, B2O3 functions to improve the thermal stability of the glass, but tends to decrease the refractive index. Therefore, from the viewpoint of increasing the refractive index while maintaining the thermal stability of the glass, the mass ratio of the total content of La2O3, Gd2O3, and Y2O3 to the total content of B2O3, La2O3, Gd2O3, and Y2O3 ((La2O3 + Gd2O3 + Y2O3) / (B2O3 + La2O3 + Gd2O3 + Y2O3)) is preferably 0.57 or greater, and more preferably 0.58 or greater, 0.59 or greater, 0.60 or greater, 0.61 or greater, 0.62 or greater, 0.63 or greater, and 0.64 or greater in that order. From the viewpoint of further reducing the specific gravity, the mass ratio ((La2O3+Gd2O3+Y2O3) / (B2O3+La2O3+Gd2O3+Y2O3)) is preferably 1.00 or less, and is more preferably less than 1.00, 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.89 or less, 0.88 or less, 0.87 or less, 0.86 or less, and 0.85 or less, in that order.

[0386] In the glass material for molding according to this embodiment, in the case of glass composition C, La2O3, Gd2O3, Y2O3, and ZrO2 increase the refractive index and improve partial dispersion characteristics, but as the ZrO2 content increases, the meltability of the glass tends to decrease. From the above viewpoints, the mass ratio of the ZrO2 content to the total content of La2O3, Gd2O3, Y2O3, and ZrO2 (ZrO2 / (La2O3+Gd2O3+Y2O3+ZrO2)) is preferably 0.01 or more, more preferably 0.02 or more, 0.03 or more, and 0.04 or more in that order, and is preferably 5.00 or less, and even more preferably 4.00 or less, 3.00 or less, and 2.00 or less in that order.

[0387] In the molding glass material according to this embodiment, in the case of glass composition C, La2O3, Gd2O3, Y2O3, and ZrO2 are all components that increase the refractive index, but ZrO2 has a greater effect of increasing the refractive index and also a greater effect of increasing dispersion (decreasing the Abbe number) than La2O3, Gd2O3, and Y2O3. From the viewpoint of maintaining low dispersion, the mass ratio of the ZrO2 content to the total content of La2O3, Gd2O3, and Y2O3 (ZrO2 / (La2O3+Gd2O3+Y2O3)) is preferably 3.30 or less, and more preferably 3.00 or less, 2.90 or less, 2.80 or less, 2.70 or less, 2.60 or less, 2.50 or less, 2.40 or less, 2.30 or less, 2.20 or less, 2.10 or less, 2.00 or less, 1.90 or less, 1.80 or less, 1.70 or less, 1.60 or less, 1.50 or less, 1.40 or less, 1.30 or less, and 1.25 or less in that order. The mass ratio (ZrO2 / (La2O3+Gd2O3+Y2O3)) can be 0.00 or more, and from the viewpoint of further increasing the refractive index, it is preferably more than 0.00, and more preferably 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, and 0.06 or more in that order.

[0388] In the glass material for molding according to this embodiment, in the case of glass composition C, the ZrO content is preferably 7.63% or less from the viewpoint of realizing desirable optical constants and improving partial dispersion characteristics, and is more preferably less than 7.63%, 7.60 or less, 7.50 or less, 7.40 or less, 7.30 or less, 7.20 or less, 7.10 or less, 7.00 or less, 6.90 or less, 6.80 or less, 6.70 or less, 6.60 or less, 6.50 or less, 6.40 or less, 6.30 or less, 6.20 or less, 6.10 or less, 6.00 or less, 5.95 or less, and 5.90 or less in this order, and particularly from the viewpoint of improving reheat devitrification resistance, is more preferably 6.00 or less, 5.50 or less, 5.00 or less, 4.00 or less, 3.00 or less, and 2.50 or less in this order. Furthermore, from the viewpoint of realizing more desirable optical constants and further improving partial dispersion characteristics, the ZrO content is preferably 0.00% or more, and more preferably in the order of more than 0.00%, 0.10% or more, 0.20% or more, 0.30% or more, 0.40% or more, 0.50% or more, 0.60% or more, 0.65% or more, 1.10% or more, and 1.60% or more.

[0389] In the glass material for molding according to this embodiment, in the case of glass composition C, MgO, CaO, SrO, BaO, and ZnO function to improve the thermal stability of the glass, but as their contents increase, the refractive index tends to decrease. On the other hand, La2O3, Gd2O3, and Y2O3 function to increase the refractive index, but as their contents increase, the thermal stability tends to decrease. From the above viewpoints, the mass ratio of the total content of MgO, CaO, SrO, BaO, and ZnO to the total content of La2O3, Gd2O3, and Y2O3 ((MgO+CaO+SrO+BaO+ZnO) / (La2O3+Gd2O3+Y2O3)) is preferably greater than 0.00, and more preferably 0.10 or more, 0.20 or more, 0.30 or more, 0.40 or more, 0.50 or more, 0.60 or more, 0.70 or more, or 0.80 or more. , 0.90 or more, 1.00 or more, 1.10 or more, 1.20 or more, 1.30 or more, 1.40 or more are more preferred in this order, and 20.00 or less is preferred, and 18.00 or less, 16.00 or less, 14.00 or less, 11.09 or less, 11.08 or less, 11.07 or less, 11.06 or less, 11.05 or less, 11.04 or less, 11.03 or less, 11.02 or less, 11.01 or less, 11.00 or less are more preferred in this order.

[0390] In the glass material for molding according to this embodiment, SrO, BaO, La2O3, Gd2O3, and Y2O3 are all components effective in maintaining low dispersion in the case of glass composition C. Therefore, from the viewpoint of maintaining even lower dispersion, the total content of SrO, BaO, La2O3, Gd2O3, and Y2O3 (SrO + BaO + La2O3 + Gd2O3 + Y2O3) is preferably 9.00% or more, and more preferably 9.50% or more, 10.00% or more, 10.50% or more, 11.00% or more, 11.50% or more, 12.00% or more, 12.50% or more, 13.00% or more, and 13.50% or more, in that order. Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition C, from the viewpoint of further reducing the specific gravity, the total content (SrO + BaO + La2O3 + Gd2O3 + Y2O3) is preferably 45.00% or less, and more preferably 40.00% or less, 35.00% or less, 30.00% or less, 29.00% or less, 28.00% or less, 27.00% or less, 26.00% or less, and 25.00% or less in that order.

[0391] In the glass material for molding according to this embodiment, in the case of glass composition C, La2O3, Gd2O3, and Y2O3 are components that function to increase the refractive index, and SiO2 is a component that maintains the thermal stability of the glass. From the viewpoint of further increasing the refractive index, the mass ratio of the total content of La2O3, Gd2O3, and Y2O3 to the total content of La2O3, Gd2O3, and SiO2 ((La2O3 + Gd2O3 + Y2O3) / (La2O3 + Gd2O3 + Y2O3 + SiO2)) is preferably 0.12 or more, and more preferably 0.13 or more. From the viewpoint of maintaining the thermal stability of the glass, the mass ratio ((La2O3+Gd2O3+Y2O3) / (La2O3+Gd2O3+Y2O3+SiO2)) is preferably 0.70 or less, and more preferably 0.60 or less, 0.50 or less, 0.49 or less, 0.48 or less, 0.47 or less, 0.46 or less, 0.45 or less, 0.44 or less, 0.43 or less, 0.42 or less, and 0.41 or less, in that order.

[0392] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the total content of SiO2 and CaO to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 ((SiO2+CaO) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is the total content of components that have a large effect of increasing the refractive index, and the numerator is the total content of components that are effective in reducing dispersion and specific gravity. From the viewpoints of achieving a high refractive index, maintaining low dispersion, reducing specific gravity, and maintaining thermal stability, the mass ratio ((SiO2+CaO) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 1.20 or less, and more preferably 1.09 or less, 1.08 or less, 1.07 or less, 1.06 or less, 1.05 or less, 1.04 or less, 1.03 or less, 1.02 or less, 1.01 or less, 0.99 or less, 0.94 or less, 0.89 or less, and 0.86 or less, in that order. Furthermore, from the viewpoint of achieving a higher refractive index, maintaining even lower dispersion, and further reducing the specific gravity, the mass ratio ((SiO2+CaO) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.25 or more, and more preferably 0.30 or more, 0.35 or more, 0.40 or more, 0.42 or more, 0.44 or more, 0.46 or more, 0.48 or more, 0.50 or more, 0.52 or more, 0.54 or more, and 0.55 or more, in that order.

[0393] In the glass material for molding according to this embodiment, in the case of glass composition C, of ​​the components that increase the refractive index, ZrO2, TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3, ZrO2 has a relatively small effect of increasing dispersion. Therefore, from the viewpoint of maintaining even lower dispersion, the mass ratio of the ZrO2 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (ZrO2 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.00 or greater, and more preferably 0.01 or greater, and 0.02 or greater in that order. From the viewpoint of maintaining the thermal stability of the glass and maintaining resistance to devitrification when the glass is heated, softened, and press-molded (stability during reheat press molding: also known as reheat press moldability), the mass ratio (ZrO2 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.21 or less, and more preferably 0.20 or less, 0.19 or less, 0.18 or less, 0.17 or less, 0.16 or less, 0.15 or less, 0.12 or less, 0.10 or less, 0.08 or less, and 0.06 or less, in that order.

[0394] In the glass material for molding according to this embodiment, in the case of glass composition C, the lower limit of the total content of LiO, NaO, and KO [LiO + NaO + KO] is preferably 0.1%, and more preferably 0.2%, 0.5%, 1.0%, 1.2%, and 1.5%, in that order. The upper limit of the total content is preferably 20%, and more preferably 15%, 10%, 8%, 6%, 4%, and 2%, in that order.

[0395] In glass composition C, when the lower limit of the total content [Li2O + Na2O + KO] satisfies the above range, the meltability of the glass can be improved and an increase in the liquidus temperature can be suppressed. When the upper limit of the total content satisfies the above range, the viscosity of the glass can be increased, the crystallization rate of the glass melt can be reduced, and stability during reheating can be improved.

[0396] In the glass material for molding according to this embodiment, in the case of glass composition C, the alkali metal oxides Li2O, Na2O, K2O, and Cs2O improve the partial dispersion characteristics, lower the liquidus temperature, and improve the thermal stability of the glass. From these viewpoints, the total content of Li2O, Na2O, K2O, and Cs2O (Li2O + Na2O + K2O + Cs2O) is preferably 0.00% or more, and more preferably in the following order: more than 0.00%, 0.05% or more, 0.10% or more, 0.15% or more, 0.20% or more, 0.25% or more, 0.28% or more, 0.60% or more, 1.10% or more, 1.30% or more, and 1.60% or more. From the viewpoint of improving chemical durability and weather resistance, the total content (Li2O+Na2O+K2O+Cs2O) is preferably 20.00% or less, and more preferably 18.00% or less, 16.00% or less, 14.00% or less, 12.00% or less, 10.00% or less, 9.00% or less, 8.00% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, 5.00% or less, 4.50% or less, 3.90% or less, 2.90% or less, and 2.40% or less in that order.

[0397] In the glass material for molding according to this embodiment, in the case of glass composition C, the upper limit of the mass ratio of the total content of Li2O, Na2O, K2O, and Cs2O to the total content of SiO2, P2O5, and B2O3 [(Li2O + Na2O + K2O + Cs2O) / (SiO2 + P2O5 + B2O3)] is preferably 1.0, and more preferably 0.7, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, and 0.08, in that order. The lower limit of this mass ratio is preferably 0.001, and more preferably 0.01, 0.02, 0.03, 0.04, 0.05, and 0.06, in that order.

[0398] In glass composition C, if the mass ratio [(Li2O + Na2O + K2O + Cs2O) / (SiO2 + P2O5 + B2O3)] is too low, the meltability may deteriorate. On the other hand, if it is too high, the viscosity of the glass during melting may decrease, reducing the thermal stability of the melt and possibly worsening the stability during reheating.

[0399] In the glass material for molding according to this embodiment, in the case of glass composition C, the upper limit of the mass ratio of the total content of Li2O, Na2O, K2O, and Cs2O to the total content of Nb2O5, TiO2, WO3, and Bi2O3 [(Li2O + Na2O + K2O + Cs2O) / (Nb2O5 + TiO2 + WO3 + Bi2O3)] is preferably 1.0, and more preferably 0.5, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, and 0.05, in that order. The lower limit of this mass ratio is preferably 0.005, and more preferably 0.01, 0.02, 0.03, and 0.04, in that order.

[0400] In glass composition C, if the mass ratio [(Li2O + Na2O + K2O + Cs2O) / (Nb2O5 + TiO2 + WO3 + Bi2O3)] is too low, the partial dispersion ratio Pg,F increases and the transmittance may deteriorate. On the other hand, if it is too high, the Abbe number increases, the refractive index decreases, and the stability during reheating may deteriorate.

[0401] In the glass material for molding according to this embodiment, in the case of glass composition C, alkali metal oxides and alkaline earth metal oxides can contribute to maintaining the meltability and thermal stability of the glass, but as their contents increase, the meltability and thermal stability of the glass tend to decrease. Therefore, from the viewpoint of maintaining the meltability and thermal stability of the glass, the total content of the alkali metal oxides Li2O, Na2O, K2O, and Cs2O and the alkaline earth metal oxides MgO, CaO, SrO, and BaO (Li2O + Na2O + K2O + Cs2O + MgO + CaO + SrO + BaO) is preferably 5.00% or more, and more preferably 7.00% or more, 9.00% or more, 10.00% or more, 12.00% or more, 14.00% or more, 15.00% or more, and most preferably 16.00% or more. It is preferably 0% or more, 16.00% or more, 17.00% or more, 18.00% or more, and 18.50% or more in that order, and is preferably 50.00% or less, and more preferably 48.00% or less, 46.00% or less, 44.00% or less, 43.00% or less, 42.00% or less, 41.00% or less, 40.00% or less, 39.00% or less, 38.00% or less, 37.00% or less, 36.00% or less, 35.00% or less, 34.50% or less, and 34.00% or less in that order.

[0402] In the glass material for molding according to this embodiment, in the case of glass composition C, alkali metal oxides and alkaline earth metal oxides function to lower the liquidus temperature and improve thermal stability, but as their content relative to the network-forming components of the glass increases, chemical durability and weather resistance tend to decrease. Also, SiO2 and B2O3 function to improve thermal stability, but as their content increases, meltability tends to decrease. From these perspectives, the mass ratio of the total content of Li2O, Na2O, K2O, Cs2O, MgO, CaO, SrO, and BaO to the total content of SiO2 and B2O3 ((Li2O + Na2O + K2O + Cs2O + MgO + CaO + SrO + BaO) / (SiO2 + B2O3)) is preferably 0.50 or more, and more preferably 0.52 or more, 0.54 or more, 0.56 or more, 0.58 or more, 0.60 or more, 0.62 or more, 0.63 or more, 0.64 or more, 0.65 or more, 0.66 or more, 0.67 or more, 0.68 or more, 0.69 or more, 0.70 or more, 0.71 or more, 0.72 or more, 0.73 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more, 0.78 or more, 0.79 or more, 0.80 or more, 0.81 or more, 0.82 or more, 0.83 or more, 0.84 or more, 0.85 or more, 0.86 or more, 0.87 or more, 0.88 or more, 0.89 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, 0.94 or It is preferably 0.64 or more, 0.66 or more, 0.68 or more, 0.70 or more, 0.72 or more, 0.74 or more, 0.75 or more, 0.76 or more, 0.77 or more, 0.78 or more, 0.79 or more in that order, and is preferably 5.00 or less, and more preferably 4.50 or less, 4.00 or less, 3.50 or less, 3.00 or less, 2.50 or less, 2.00 or less, 1.90 or less, 1.80 or less, 1.70 or less, 1.65 or less, 1.60 or less in that order.

[0403] In the glass material for molding according to this embodiment, in the case of glass composition C, of ​​Li2O, Na2O, and K2O, Li2O is the component that is least likely to lower the refractive index. Therefore, from the viewpoint of achieving a higher refractive index, the mass ratio of the Li2O content to the total content of Li2O, Na2O, and K2O (Li2O / (Li2O+Na2O+K2O)) is preferably 0.00 or more, and is more preferably greater than 0.00, 0.10 or more, 0.20 or more, 0.30 or more, 0.40 or more, and 0.45 or more in that order. On the other hand, the mass ratio (Li2O / (Li2O+Na2O+K2O)) can be, for example, 1.00 or less, and from the viewpoint of suppressing a decrease in reheat devitrification resistance, can also be 0.99 or less, 0.98 or less, 0.95 or less, 0.90 or less, 0.80 or less, 0.70 or less, 0.65 or less, 0.60 or less, or 0.50 or less.

[0404] In the glass material for molding according to this embodiment, in the case of glass composition C, LiO, NaO, KO, MgO, CaO, SrO, BaO, and ZnO have the functions of improving the thermal stability of the glass and improving the meltability of the glass, but as the total content of LiO, NaO, and KO increases, the glass tends to exhibit high dispersibility. Therefore, from the viewpoint of obtaining more desirable dispersibility, the mass ratio of the total content of LiO, NaO, and KO to the total content of MgO, CaO, SrO, BaO, and ZnO ((LiO+NaO+KO) / (MgO+CaO+SrO+BaO+ZnO)) is preferably 0.00 or more, and more preferably greater than 0.00, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, and 0.05 or more, in that order; it is preferably 4.00 or less, and more preferably 3.50 or less, 3.00 or less, 2.50 or less, 2.00 or less, 1.50 or less, 1.00 or less, 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, and 0.35 or less, in that order.

[0405] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the total content of Li2O, Na2O, and K2O to the total content of SiO2 and B2O3 ((Li2O + Na2O + K2O) / (SiO2 + B2O3)) is preferably 1.00 or less, and more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.35 or less, 0.30 or less, and 0.25 or less, in that order, from the viewpoint of maintaining thermal stability and / or maintaining reheat press formability. From the viewpoint of maintaining meltability and / or reducing the partial dispersion ratio to provide a glass that is suitable for correcting high-order chromatic aberrations, the mass ratio ((Li2O+Na2O+K2O) / (SiO2+B2O3)) is preferably 0.00 or greater, and more preferably greater than 0.00, 0.01 or greater, 0.02 or greater, 0.03 or greater, 0.04 or greater, and 0.05 or greater, in that order.

[0406] In the glass material for molding according to this embodiment, in the case of glass composition C, the LiO content is preferably 0.00% or more, and more preferably 0.05% or more, 0.10% or more, 0.15% or more, 0.20% or more, 0.25% or more, 0.30% or more, 0.40% or more, 0.50% or more, and 0.60% or more in this order. The LiO content is preferably 14.00% or less, and more preferably 12.00% or less, 10.00% or less, 8.00% or less, 7.00% or less, 6.50% or less, 6.00% or less, 5.50% or less, and 5.00% or less in this order. Setting the LiO content within the above range is preferable from the viewpoint of realizing more desirable optical constants and maintaining chemical durability, weather resistance, and stability during reheating.

[0407] In the glass material for molding according to this embodiment, in the case of glass composition C, the Na2O content is preferably 0.00% or more. The Na2O content is preferably 10.00% or less, and more preferably 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, and 2.00% or less in that order. Setting the Na2O content within the above range is preferred from the viewpoint of improving partial dispersion characteristics.

[0408] In the glass material for molding according to this embodiment, in the case of glass composition C, the K2O content is preferably 0.00% or more. The K2O content is preferably 10.00% or less, and more preferably 8.00% or less, 7.00% or less, 6.00% or less, 5.00% or less, 4.00% or less, 3.00% or less, and 2.00% or less, in that order. Setting the K2O content within the above range is preferred from the viewpoint of improving the thermal stability of the glass.

[0409] In the glass material for molding according to this embodiment, in the case of glass composition C, the CsO content is preferably 5.00% or less, and more preferably 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less in that order, and may even be 0%.

[0410] In the glass material for molding according to this embodiment, in the case of glass composition C, the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (TiO2 + Nb2O5 + Ta2O5 + WO3 + Bi2O3) is preferably 30.00% or more, from the viewpoint of achieving an even higher refractive index, and is more preferably 31.00% or more, 32.00% or more, 33.00% or more, 34.00% or more, 35.00% or more, 36.00% or more, 36.50% or more, 37.00% or more, and 37.55% or more in that order. From the viewpoint of further reducing the specific gravity and improving the thermal stability, the total content of TiO2, Nb2O5, Ta2O5, WO3 and Bi2O3 (TiO2 + Nb2O5 + Ta2O5 + WO3 + Bi2O3) is preferably 60.00% or less, and more preferably 58.00% or less, 56.00% or less, 54.00% or less, 52.00% or less, 51.00% or less, 50.00% or less, 49.50% or less, 49.00% or less, and 48.50% or less in that order.

[0411] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the total content of SiO2 and B2O3 to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 ((SiO2+B2O3) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.75 or less, from the viewpoint of obtaining glass with a high refractive index while suppressing an increase in specific gravity. In addition to the above, from the viewpoint of achieving a desirable Abbe number vd, improving partial dispersion characteristics, and enhancing devitrification resistance, the mass ratio ((SiO2+B2O3) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.16 or more, and more preferably 0.20 or more, 0.25 or more, 0.30 or more, 0.35 or more, 0.36 or more, 0.37 or more, 0.38 or more, 0.39 or more, 0.40 or more, 0.41 or more, and 0.42 or more in that order; it is preferably 0.75 or less, and more preferably 0.74 or less, 0.73 or less, 0.72 or less, 0.71 or less, 0.70 or less, 0.69 or less, 0.68 or less, 0.67 or less, 0.66 or less, 0.65 or less, and 0.64 or less in that order.

[0412] In the glass composition C of the molding glass material according to this embodiment, SiO2 and B2O3 act to decrease the refractive index and decrease dispersion (increase the Abbe number). Meanwhile, TiO2, Nb2O5, Ta2O5, WO3, Bi2O3, and ZrO2 are high-refractive-index, high-dispersion components. To further increase the refractive index, the mass ratio of the total content of SiO2 and B2O3 to the total content of TiO2, Nb2O5, Ta2O5, WO3, Bi2O3, and ZrO2 ((SiO2 + B2O3) / (TiO2 + Nb2O5 + Ta2O5 + WO3 + Bi2O3 + ZrO2)) is preferably 0.64 or less, more preferably 0.63 or less, 0.62 or less, 0.61 or less, 0.60 or less, 0.59 or less, and 0.58 or less, in that order. On the other hand, in the case of glass composition C, from the viewpoint of suppressing high dispersion, the mass ratio ((SiO2+B2O3) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3+ZrO2)) is preferably 0.13 or more, and is more preferably 0.15 or more, 0.20 or more, 0.25 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.30 or more, 0.31 or more, 0.32 or more, 0.33 or more, 0.34 or more, 0.35 or more, 0.36 or more, 0.37 or more, and 0.38 or more, in that order.

[0413] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the total content of Li2O, Na2O, and K2O to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 ((Li2O + Na2O + K2O) / (TiO2 + Nb2O5 + Ta2O5 + WO3 + Bi2O3)) is preferably 0.00 or more, and more preferably 0.01 or more, from the viewpoint of improving partial dispersion characteristics and transmittance. From the viewpoint of maintaining the thermal stability and / or reheat press formability of the glass, the mass ratio ((Li2O + Na2O + K2O) / (TiO2 + Nb2O5 + Ta2O5 + WO3 + Bi2O3)) is preferably 0.67 or less, and more preferably 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less, 0.20 or less, 0.15 or less, and 0.10 or less, in that order.

[0414] In the glass material for molding according to this embodiment, in the case of glass composition C, MgO, CaO, SrO, BaO, and ZnO function to improve the thermal stability of the glass, but increasing their contents tends to lower the refractive index and make the glass lower dispersion. On the other hand, TiO2, Nb2O5, WO3, and Bi2O3 tend to increase the refractive index and make the glass higher dispersion, but increasing their contents tends to lower the thermal stability. From the above viewpoints, the mass ratio of the total content of MgO, CaO, SrO, BaO and ZnO to the total content of TiO2, Nb2O5, Ta2O5, WO3 and Bi2O3 ((MgO+CaO+SrO+BaO+ZnO) / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.09 or more, more preferably 0.10 or more, 0.15 or more, 0.20 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, 0.25 or more. , 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.30 or more, 0.31 or more, 0.32 or more, 0.35 or more, 0.40 or more, 0.45 or more are more preferred in this order, and 1.66 or less is preferred, and 1.60 or less, 1.50 or less, 1.40 or less, 1.30 or less, 1.20 or less, 1.10 or less, 1.00 or less, 0.95 or less, 0.90 or less, 0.88 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less are more preferred in this order.

[0415] In the glass material for molding according to this embodiment, in the case of glass composition C, among MgO, CaO, SrO, BaO, and ZnO, MgO and CaO suppress the increase in the specific gravity of the glass compared to SrO, BaO, and ZnO, and 100-300 and α maxTherefore, from the viewpoint of suppressing an increase in specific gravity, the mass ratio of the total content of ZnO, SrO, and BaO to the total content of MgO and CaO ((ZnO+SrO+BaO) / (MgO+CaO)) is preferably 1.98 or less, and more preferably 1.96 or less, 1.94 or less, 1.92 or less, 1.90 or less, 1.88 or less, 1.86 or less, 1.85 or less, 1.84 or less, 1.83 or less, 1.82 or less, 1.81 or less, 1.80 or less, 1.79 or less, 1.78 or less, 1.50 or less, 1.20 or less, 0.95 or less, 0.80 or less, 0.70 or less, 0.60 or less, and 0.50 or less in that order.

[0416] On the other hand, in the glass material for molding according to this embodiment, in the case of glass composition C, the introduction of small amounts of SrO, BaO, and ZnO increases the stability of the glass and also increases the refractive index. Therefore, from the viewpoint of maintaining low dispersion, the mass ratio ((ZnO+SrO+BaO) / (MgO+CaO)) is preferably 0.17 or more, and more preferably 0.18 or more, 0.19 or more, 0.20 or more, 0.25 or more, and 0.30 or more in that order.

[0417] In the glass material for molding according to this embodiment, in the case of glass composition C, the lower limit of the mass ratio of the total content of Li2O, Na2O, and K2O to the total content of Nb2O5 and TiO2 [(Li2O + Na2O + K2O) / (Nb2O5 + TiO2)] is preferably 0.001, and more preferably 0.01, 0.02, 0.03, and 0.04 in that order. The upper limit of this mass ratio is preferably 1.00, and more preferably 0.50, 0.30, 0.20, 0.10, 0.08, and 0.06 in that order.

[0418] In glass composition C, from the viewpoint of obtaining desired optical constants while maintaining the melting characteristics, thermal stability, and stability during reheating of the glass, it is preferable that the mass ratio [(Li2O+Na2O+K2O) / (Nb2O5+TiO2)] be in the above range.

[0419] In the glass material for molding according to this embodiment, in the case of glass composition C, when TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 are compared with La2O3, Gd2O3, and Y2O3 in terms of their contribution to dispersibility, TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 tend to make the glass less dispersible, while La2O3, Gd2O3, and Y2O3 tend to make the glass more dispersible. From the viewpoint of obtaining desirable dispersibility, the mass ratio of the total content of La2O3, Gd2O3, and Y2O3 to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 ((La2O3 + Gd2O3 + Y2O3) / (TiO2 + Nb2O5 + Ta2O5 + WO3 + Bi2O3)) is preferably more than 0.00, and more preferably 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, and 0.07 or more, in that order; it is preferably 1.00 or less, and more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, and 0.32 or less, in that order.

[0420] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the TiO2 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (TiO2 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.00 or more, from the viewpoint of achieving a high refractive index and a low specific gravity, and is more preferably greater than 0.00, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.15 or more, 0.20 or more, 0.25 or more, and 0.30 or more in that order. On the other hand, from the viewpoint of suppressing coloration of the glass and enhancing the stability of the glass, it is preferably 1.00 or less, and more preferably less than 1.00, 0.95 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, 0.73 or less, 0.60 or less, 0.50 or less, 0.45 or less, and 0.40 or less in that order.

[0421] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the Nb2O5 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (Nb2O5 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 0.00 or more, from the viewpoint of improving partial dispersion characteristics, and is more preferably greater than 0.00, 0.01 or more, 0.05 or more, 0.10 or more, 0.15 or more, 0.20 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, 0.25 or more, 0.26 or more, and 0.27 or more in that order. On the other hand, in order to improve the thermal stability of the glass and to improve reheating devitrification resistance, the value is preferably 1.00 or less, and more preferably in the order of less than 1.00, 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.85 or less, 0.80 or less, 0.75 or less, 0.70 or less, and 0.66 or less.

[0422] In the glass material for molding according to this embodiment, in the case of glass composition C, the mass ratio of the Ta2O5 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (Ta2O5 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 1.00 or less, in order of preference 0.80 or less, 0.60 or less, 0.40 or less, 0.30 or less, 0.20 or less, and 0.10 or less, and is particularly preferably 0.

[0423] In the molding glass material according to this embodiment, in the case of glass composition C, among the high-refractive-index, high-dispersion components TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3, WO3 and Bi2O3 largely function to increase the specific gravity. Therefore, from the viewpoint of further reducing the specific gravity, the mass ratio of the WO3 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (WO3 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 1.00 or less, more preferably 0.80 or less, 0.60 or less, 0.40 or less, 0.30 or less, 0.20 or less, and 0.10 or less, in that order, is particularly preferred. From a similar viewpoint, in the case of glass composition C, the mass ratio of the Bi2O3 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 (Bi2O3 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3)) is preferably 1.00 or less, and more preferably 0.80 or less, 0.60 or less, 0.40 or less, 0.30 or less, 0.20 or less, and 0.10 or less, in that order, is more preferable, and 0 is particularly preferable.

[0424] In the glass composition C of the molding glass material according to this embodiment, Li2O3, La2O3, Gd2O3, Y2O3, ZrO2, TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 function to increase the refractive index, while SiO2, B2O3, Na2O, K2O, MgO, CaO, SrO, BaO, and ZnO tend to decrease the refractive index. From the viewpoint of achieving a higher refractive index, the mass ratio of SiO2, B2O3, Na2O, K2O, MgO, CaO, SrO, BaO, and ZnO to the total content of Li2O3, La2O3, Gd2O3, Y2O3, ZrO2, TiO2, Nb2O5, Ta2O5, WO3, and Bi2O3 is ((SiO2 + B2O3 + Na2O + K2O + MgO + CaO + SrO + BaO + ZnO) / (Li2O + La2O3 + Gd2O3 + Y2O3 + ZrO2 + TiO2 + Nb2O5 + Ta2O5 + WO 3+Bi2O3)) is preferably 0.12 or more, and more preferably 0.15 or more, 0.20 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.45 or more, 0.50 or more, and 0.55 or more in that order, and is preferably 2.83 or less, and more preferably 2.80 or less, 2.60 or less, 2.40 or less, 2.20 or less, 2.00 or less, 1.80 or less, 1.70 or less, 1.60 or less, 1.50 or less, 1.40 or less, 1.30 or less, 1.26 or less, 1.25 or less, and 1.24 or less in that order.

[0425] In the glass material for molding according to this embodiment, in the case of glass composition C, TiO2, Nb2O5, Ta2O5, WO3, Bi2O3, and ZrO2 function to increase the refractive index of the glass, but as the ZrO2 content increases, the meltability of the glass tends to decrease. From the above perspectives, the mass ratio of the ZrO2 content to the total content of TiO2, Nb2O5, Ta2O5, WO3, Bi2O3, and ZrO2 (ZrO2 / (TiO2+Nb2O5+Ta2O5+WO3+Bi2O3+ZrO2)) is preferably 0.00 or more, more preferably 0.01 or more and 0.02 or more, and is preferably 0.17 or less, and more preferably 0.16 or less, 0.15 or less, 0.14 or less, and 0.13 or less, in that order.

[0426] In the glass composition C of the molding glass material according to this embodiment, TiO2, Nb2O5, WO3, and ZnO tend to increase the refractive index and make the glass more highly dispersible, but when these are contained in large amounts, the thermal stability of the glass tends to decrease. On the other hand, MgO, CaO, SrO, and BaO tend to make the glass more low-dispersible and have the function of improving thermal stability, but when these are contained in large amounts, the refractive index tends to decrease. From the above viewpoints, the mass ratio of the total content of MgO, CaO, SrO and BaO to the total content of TiO2, Nb2O5, WO3 and ZnO ((MgO + CaO + SrO + BaO) / (TiO2 + Nb2O5 + WO3 + ZnO)) is preferably 0.10 or more, and more preferably 0.15 or more, 0.20 or more, 0.25 or more, 0.26 or more, 0.27 or more, 0.28 or more, 0.29 or more, 0.30 or more, 0.31 or more, and 0.32 or more in that order; it is preferably 1.50 or less, and more preferably 1.30 or less, 1.20 or less, 1.10 or less, 1.00 or less, 0.95 or less, 0.90 or less, and 0.87 or less in that order.

[0427] In the glass material for molding according to this embodiment, in the case of glass composition C, the TiO content is preferably 0.00% or more, more preferably greater than 0.00%, 0.50% or more, 1.00% or more, 1.50% or more, 2.00% or more, 2.50% or more, 3.00% or more, 3.50% or more, and 4.00% or more, and is preferably 50.00% or less, and more preferably 45.0% or less, 40.00% or less, 38.00% or less, 36.00% or less, 35.00% or less, 34.00% or less, 32.00% or less, 31.00% or less, 30.00% or less, 29.50% or less, and 29.00% or less. The TiO content within the above range is preferable from the viewpoint of realizing more desirable optical constants and reducing the raw material cost of the glass.

[0428] In the glass material for molding according to this embodiment, in the case of glass composition C, the Nb2O5 content is preferably 0.00% or more, and more preferably in the order of greater than 0.00%, 1.00% or more, 2.00% or more, 3.00% or more, 4.00% or more, 5.00% or more, 6.00% or more, 7.00% or more, 8.00% or more, 9.00% or more, 10.00% or more, and 10.50% or more. Furthermore, the Nb2O5 content is preferably 60.00% or less, and more preferably in the order of 58.00% or less, 56.00% or less, 54.00% or less, 52.00% or less, 50.00% or less, 49.00% or less, 48.00% or less, 47.00% or less, 46.00% or less, 45.00% or less, and 44.00% or less. The Nb2O5 content in the above range is preferable from the viewpoint of realizing more desirable optical constants, further lowering the specific gravity, and improving the partial dispersion characteristics.

[0429] In the glass material for molding according to this embodiment, in the case of glass composition C, the Ta2O5 content can be 0.00% or more. The Ta2O5 content is preferably 5.00% or less, and more preferably 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less in that order. A Ta2O5 content within the above range is preferred from the viewpoints of improving the thermal stability and melting property of the glass and further reducing the specific gravity.

[0430] In the glass material for molding according to this embodiment, in the case of glass composition C, the WO content can be 0.00% or more. The WO content is preferably 5.00% or less, and more preferably 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less, in that order. A WO content within the above range is preferred from the viewpoints of improving the transmittance of the glass, improving partial dispersion characteristics, and further lowering the specific gravity.

[0431] In the glass material for molding according to this embodiment, in the case of glass composition C, the Bi2O3 content can be 0.00% or more. The Bi2O3 content is preferably 5.00% or less, and more preferably 4.00% or less, 3.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less in that order. A Bi2O3 content within the above range is preferred from the viewpoints of improving the thermal stability of the glass, improving the partial dispersion characteristics, and further lowering the specific gravity.

[0432] In the glass material for molding according to this embodiment, in the case of glass composition C, GeO2 functions to increase the refractive index but is a very expensive component. From the viewpoint of reducing the manufacturing cost of the glass, the GeO2 content can be set to 0.00% or more, and is preferably 2.00% or less, with 1.50% or less, 1.00% or less, and 0.50% or less being more preferred in that order.

[0433] In the glass material for molding according to this embodiment, in the case of glass composition C, in addition to the above components, one or more of P2O5, Al2O3, and the like may also be contained. The P2O5 content can be 0.00% or more, and is preferably 10.00% or less, with 8.00% or less, 6.00% or less, 4.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less being more preferred in that order. A P2O5 content within the above range is preferred from the viewpoint of improving the thermal stability and partial dispersion characteristics of the glass. The Al2O3 content can be 0.00% or more, and is preferably 10.00% or less, with 8.00% or less, 6.00% or less, 4.00% or less, 2.00% or less, 1.00% or less, and 0.50% or less being more preferred in that order. An Al2O3 content within the above range is preferred from the viewpoint of improving the devitrification resistance and thermal stability of the glass.

[0434] Pb, As, Cd, Tl, Be, and Se are all toxic, and therefore it is preferable not to include these elements, i.e., not to introduce these elements into the glass as glass components. U, Th, and Ra are all radioactive elements, and therefore it is preferable not to include these elements, i.e., not to introduce these elements into the glass as glass components. V, Cr, Mn, Fe, Co, Ni, Cu, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Ce are undesirable elements to be contained in glass for optical elements because they increase the coloration of the glass or are sources of fluorescence. Therefore, it is preferable not to contain these elements, i.e., not to introduce these elements into the glass as glass components.

[0435] Sb and Sn are elements that can be added as desired and function as fining agents. The amount of Sb added is preferably in the range of 0 to 0.11 mass%, more preferably 0.01 to 0.08 mass%, and even more preferably 0.02 to 0.05 mass%, calculated as Sb2O3, when the total content of glass components other than Sb2O3 is taken as 100 mass%. The amount of Sn added is converted to SnO2 and, when the total content of glass components other than SnO2 is taken as 100 mass%, is preferably in the range of 0 to 0.50 mass%, more preferably in the range of 0 to 0.20 mass%, and even more preferably 0 mass%.

[0436] <Glass properties> (refractive index nd) In the glass material for molding according to this embodiment, glass composition C can produce a glass with a high refractive index. In the case of glass composition C, the refractive index nd is preferably 1.860 or more, and is more preferably 1.865 or more, 1.870 or more, 1.875 or more, 1.880 or more, 1.885 or more, 1.890 or more, 1.895 or more, and 1.900 or more in that order. Furthermore, the refractive index nd can be, for example, 1.950 or less, 1.945 or less, 1.940 or less, 1.935 or less, 1.930 or less, or 1.925 or less. In the present invention and this specification, "refractive index" means "refractive index nd."

[0437] (Abbe number νd) The Abbe number vd is a value that represents properties related to dispersibility, and is expressed as vd=(nd-1) / (nF-nC) using the refractive indices nd, nF, and nC at the d-line, F-line, and C-line. In the glass material for molding according to this embodiment, in the case of glass composition C, from the viewpoint of usefulness as a material for optical elements, the Abbe number vd is preferably 22.00 or more, and is more preferably 22.50 or more, 23.00 or more, 23.50 or more, 24.00 or more, 24.20 or more, 24.40 or more, 24.60 or more, 24.70 or more, 24.80 or more, 25.00 or more, 25.50 or more, 25.60 or more, 25.80 or more, and 26.00 or more in that order. From the same viewpoint, the Abbe number vd is preferably 30.00 or less, and more preferably 29.50 or less, 29.00 or less, 28.50 or less, 28.40 or less, 28.30 or less, 28.20 or less, 28.10 or less, 28.00 or less, 27.90 or less, 27.80 or less, and 27.70 or less in that order.

[0438] Furthermore, in the glass material for molding according to this embodiment, in the case of glass composition C, from the viewpoint of usefulness as a material for optical elements, it is also preferable that the refractive index nd and Abbe number νd satisfy one or more of the following relational expressions: nd≧-0.0025νd+1.925 nd≧-0.0025νd+1.935 nd≦-0.0025νd+1.995 nd≦-0.0025νd+2.005

[0439] (specific gravity d) The refractive power of the optical elements that make up an optical system is determined by the refractive index of the glass that makes up the optical element and the curvature of the optically functional surface of the optical element (the surface through which the light rays to be controlled enter and exit). Increasing the curvature of the optically functional surface also increases the thickness of the optical element. As a result, the optical element becomes heavier. In contrast, if glass with a high refractive index is used, a large refractive power can be obtained without increasing the curvature of the optically functional surface. From the above, if the refractive index can be increased while suppressing an increase in the specific gravity of the glass, it will be possible to reduce the weight of an optical element having a certain refractive power. From the above viewpoints, in the glass material for molding according to this embodiment, in the case of glass composition C, the specific gravity d is preferably 4.100 or less, and is more preferably 4.095 or less, 4.090 or less, 4.085 or less, 4.080 or less, 4.050 or less, 4.000 or less, 3.995 or less, 3.990 or less, and 3.985 or less in that order. Since a lower specific gravity is preferable from the viewpoint of reducing the weight of the optical element, the lower limit of the specific gravity is not particularly limited. In one embodiment, the specific gravity can be 3.400 or more, 3.450 or more, 3.500 or more, 3.550 or more, 3.600 or more, 3.650 or more, 3.700 or more, or 3.750 or more.

[0440] (d / nd) From the same viewpoint as described above regarding the specific gravity d, in the glass material for molding according to this embodiment, in the case of glass composition C, the value (d / nd) obtained by dividing the specific gravity d by the refractive index nd is preferably 4.35 or less, and more preferably 4.00 or less, 3.50 or less, 3.00 or less, 2.90 or less, 2.80 or less, 2.70 or less, 2.60 or less, 2.50 or less, 2.40 or less, 2.30 or less, 2.20 or less, and 2.15 or less in that order. A smaller value of (d / nd) is preferable from the viewpoint of reducing the weight of optical elements, so there is no particular lower limit for (d / nd). In one embodiment, (d / nd) can be, for example, 1.74 or more, 1.76 or more, 1.78 or more, 1.80 or more, 1.82 or more, 1.84 or more, 1.85 or more, 1.86 or more, 1.87 or more, 1.88 or more, 1.89 or more, 1.90 or more, 1.91 or more, 1.92 or more, 1.93 or more, 1.94 or more, or 1.95 or more.

[0441] (Coloring degree λ5) In the glass material for molding according to this embodiment, in the case of glass composition C, the light transmittance of the glass, specifically, the suppression of the shift of the optical absorption edge on the short wavelength side to longer wavelengths, can be evaluated by the coloring degree λ5. The coloring degree λ5 represents the wavelength at which the spectral transmittance (including surface reflection loss) of a 10 mm thick glass is 5% from the ultraviolet to visible range. In the case of glass composition C, the spectral transmittance is, for example, more specifically, the spectral transmittance obtained by using a glass sample having parallel flat surfaces polished to a thickness of 10.0±0.1 mm and illuminating light perpendicularly to the polished surface, i.e., Iout / Iin, where Iin is the intensity of light incident on the glass sample and Iout is the intensity of light transmitted through the glass sample. The coloring degree λ5 allows quantitative evaluation of the absorption edge on the short wavelength side of the spectral transmittance. When bonding lenses together with an ultraviolet-curable adhesive to produce a cemented lens, the adhesive is cured by irradiating it with ultraviolet light through an optical element. From the viewpoint of efficiently curing the ultraviolet-curable adhesive, it is preferable that the absorption edge on the short wavelength side of the spectral transmittance is in a short wavelength range. The coloring degree λ5 can be used as an index for quantitatively evaluating this absorption edge on the short wavelength side. In the case of glass composition C, a λ5 of 400 nm or less can be preferably exhibited. The λ5 is preferably 395 nm or less, 390 nm or less, 385 nm or less, and 380 nm or less, in that order. A lower λ5 is preferable, and the lower limit is not particularly limited.

[0442] (glass transition temperature Tg) In the glass material for molding according to this embodiment, in the case of glass composition C, the glass transition temperature Tg is preferably 560°C or higher from the viewpoint of machinability. Glass with a high glass transition temperature is preferred because it tends to be less likely to break when mechanically processing the glass, such as cutting, milling, grinding, and polishing. From the viewpoint of machinability, the glass transition temperature Tg is more preferably 570°C or higher, and further preferably 580°C or higher, 590°C or higher, and 600°C or higher in that order. On the other hand, from the viewpoint of reducing the burden on the annealing furnace and the molding die, the glass transition temperature Tg is preferably 800°C or lower, and more preferably 790°C or lower, 780°C or lower, 770°C or lower, 760°C or lower, 750°C or lower, and 740°C or lower in that order.

[0443] The glass transition temperature Tg can be determined as follows. In differential scanning calorimetry, when a glass sample is heated, an endothermic behavior associated with a change in specific heat, i.e., an endothermic peak, appears, and when the temperature is further increased, an exothermic peak appears. In differential scanning calorimetry, a differential scanning calorimetry curve (DSC curve) is obtained, with the horizontal axis representing temperature and the vertical axis representing quantities corresponding to the heat generation and endothermic heat of the sample. The glass transition temperature Tg is determined by the intersection of the tangent to the point where the slope of this curve becomes maximum when an endothermic peak appears from the baseline and the baseline. The glass transition temperature Tg can be measured by using glass that has been thoroughly crushed in a mortar or the like as a sample, using a differential scanning calorimeter, and at a heating rate of 10°C / min.

[0444] (liquidus temperature) The thermal stability of glass includes resistance to devitrification when molten glass is formed, and resistance to devitrification when glass that has been solidified is reheated. The liquidus temperature LT can be used as a guide for determining devitrification resistance during forming of a glass melt. It can be said that the lower the liquidus temperature, the better the devitrification resistance. With glasses with high liquidus temperatures, the temperature of the glass melt, i.e., the glass melt, must be maintained at a high temperature to prevent devitrification. This can lead to phenomena such as volatilization of easily volatile components, accelerated corrosion of the crucible, and, particularly in the case of a crucible made of a precious metal, the dissolution of precious metal ions into the glass melt, discoloring the glass, and reduced viscosity during forming, making it difficult to form a highly homogeneous glass. Therefore, for glass composition C, the liquidus temperature is preferably 1400°C or lower, and more preferably 1370°C or lower, 1340°C or lower, 1310°C or lower, 1280°C or lower, 1270°C or lower, 1260°C or lower, and 1250°C or lower, in that order. The liquidus temperature can be, for example, 1000°C or higher, 1050°C or higher, or 1100°C or higher, but can also be higher than the values ​​exemplified here.

[0445] The "liquidus temperature" in the present invention and this specification is determined by the following method. Using a differential scanning calorimeter, a 0.02 ml sample of crushed glass was heated to 1350 °C at a heating rate of 10 °C / min in a nitrogen atmosphere with a nitrogen flow rate of 0.3 L / min. The liquidus temperature was determined as the end point of the endothermic peak, which occurs when crystals formed in the glass during the heating process melt above the glass transition temperature and crystallization temperature. Figure 1 shows a schematic diagram of a differential scanning calorimeter (DSC) curve. The horizontal axis represents temperature, with higher temperatures moving to the right and lower temperatures moving to the left. The vertical axis represents the heat generation and endothermic peaks of the sample, with the area above the baseline (dotted line) representing heat generation and the area below representing endothermic peaks. The precipitation of crystals during the heating process corresponds to the exothermic peak, and the melting of the precipitated crystals corresponds to the endothermic peak. The temperature at which the crystals melt into a molten liquid is the liquidus temperature. The liquidus temperature is determined as the temperature at the intersection of the tangent to the higher temperature side of the endothermic peak and the baseline.

[0446] (Glass material manufacturing) Glass according to an embodiment of the present invention can be produced by blending glass raw materials to achieve the predetermined composition. For example, multiple compounds are blended and thoroughly mixed to form batch raw materials, which are then placed in a quartz crucible or platinum crucible for rough melting. The resulting molten material is cooled and crushed to produce cullet. The cullet is then placed in a platinum crucible, heated, and remelted to form a glass melt. This is then cooled, clarified, and homogenized, and the glass melt is poured into a mold whose temperature has been adjusted so that the glass melt reaches a temperature Tx below Tg (Step 1), and maintained at Tx (Step 2). The glass is then cooled at −30° C. / hr for 4 hours to ensure that the temperature is below the strain point of the glass (Step 3), and then allowed to cool at a rate slow enough to prevent the glass from breaking, until it can be removed from the furnace (Step 4).

[0447] The compounds used when preparing the batch raw materials are not particularly limited as long as they can introduce desired glass components into the glass to achieve desired contents. Examples of such compounds include oxides, carbonates, nitrates, hydroxides, and fluorides.

[0448] Steps 1 to 4 will be explained below.

[0449] (Process 1) In step 1, the molten glass is poured into a mold whose temperature has been adjusted to reach a temperature Tx below the glass transition temperature Tg. By controlling the temperature of the molten glass as described above, the thermal energy applied to the glass can be reduced, thereby suppressing the movement of atoms within the glass. As a result, atomic movement is restricted before structural factors within the glass, such as the bond distances and bond angles between atoms, become homogenized. By maintaining a disordered glass structure similar to that in the molten state, a glass material with excellent stability when reheated can be obtained.

[0450] The temperature of the molten glass before step 1 is usually between the liquidus temperature and the melting temperature of the glass. In step 1, the glass temperature when the molten glass is poured into the mold is the temperature at which the glass melts, and is generally in the range of 1500°C to 1100°C, preferably 1400°C to 1200°C. Therefore, in step 1, the molten glass is cooled before being poured into the mold. This cooling is usually achieved by allowing the glass to cool naturally in the atmosphere. However, if the cooling rate is too fast, some parts of the glass may become so viscous that they no longer flow, or may solidify. This can hinder the homogenization of the glass and may even cause cracks or breakage in the glass. Therefore, the lower limit of the cooling rate in step 1 is preferably about 1°C / sec, with 3°C / sec and 6°C / sec being more preferred. The upper limit of the cooling rate is preferably 20°C / sec, and more preferably 15°C / sec, 12°C / sec, and 10°C / sec in that order.

[0451] (Process 2) In step 2, the glass melt is maintained at a temperature Tx. The maintenance temperature Tx in step 2 is preferably lower than the glass transition temperature Tg, with the upper limit being, in order of preference, Tg-1°C, Tg-5°C, Tg-10°C, Tg-15°C, and Tg-20°C. By setting the upper limit of the maintenance temperature Tx within the above range, the disorder of the glass structure is increased, and a glass material with excellent stability when reheated can be obtained.

[0452] The lower limit of the holding temperature Tx in step 2 is preferably Tg-100°C, and more preferably Tg-90°C, Tg-80°C, Tg-70°C, Tg-60°C, and Tg-50°C in that order. In particular, it is preferable that Tx is not too far below the strain point, and it is more preferable that it is equal to or higher than the strain point. By setting the lower limit of the holding temperature Tx within the above range, it is possible to remove excess internal strain in the glass, suppress deterioration of the glass workability in subsequent steps, or prevent breakage of the glass bulk. In the case of processes in which deterioration of the glass workability in subsequent steps is not an issue, the lower limit of the temperature in step 2 is not particularly specified.

[0453] The holding time in step 2 tends to be longer as the thickness of the glass increases and as the volume of the glass increases in order to soak the high-temperature glass cooled from the molten state, but is preferably 10 minutes or more, and can also be 20 minutes or more, or 30 minutes or more. From the viewpoint of productivity and maintaining the thermal stability of the glass, the upper limit of the holding time is sufficient to be less than 3 hours, and may even be less than 2 hours, less than 1.5 hours, or less than 1.0 hour. If the holding time is too long, the disordered state of atomic arrangement in the molten state is not maintained, and the atomic arrangement becomes more ordered, reducing the thermal stability of the glass and increasing α max also tends to be larger.

[0454] (Step 3) In step 3, the glass is cooled at -30°C / hr for 4 hours to ensure that the temperature is below the strain point during annealing. When the temperature Tx is higher than the strain point, the cooling time is preferably 4 hours or more, more preferably 5 hours or more, and even more preferably 6 hours or more. When the temperature Tx is lower than the strain point, the cooling time can be less than 4 hours.

[0455] (Step 4) In step 4, the glass is cooled at a rate slow enough to prevent cracking, down to a temperature at which it can be removed from the furnace. The cooling rate in step 4 is preferably less than -50°C / hr, and can be approximately -10°C / hr or -30°C / hr. A rate slower than -1°C / hr may impair productivity. The temperature at which the glass can be removed from the furnace depends on the insulation conditions outside the furnace, but is preferably approximately 100°C or less, with 80°C or less, 60°C or less, 40°C or less, and 20°C or less being more preferred in this order. Expressed in terms of the difference from room temperature, the upper limit of the temperature at which the glass can be removed from the furnace is preferably room temperature + 50°C, and more preferably room temperature + 40°C, room temperature + 30°C, room temperature + 20°C, and room temperature + 10°C in this order. The lower limit of the temperature at which the glass can be removed from the furnace may be room temperature.

[0456] The glass can be slowly cooled by any known method that can obtain the above temperature profile, such as a temperature-programmable slow cooling furnace.

[0457] By setting the cooling rate in step 1 and the holding temperature Tx in step 2 within the above ranges, the disorder of the glass structure is increased, and a glass material with excellent stability when reheated can be obtained. Furthermore, by cooling and slowly cooling the glass as in steps 3 and 4, distortion in the glass can be removed, and the workability of the glass in subsequent steps can be maintained.

[0458] As the optical glass according to the embodiment of the present invention, the glass material for molding according to the embodiment of the present invention can be used as it is.

[0459] (Manufacturing of optical elements, etc.) To produce an optical element using the glass material for molding according to an embodiment of the present invention, a known method may be applied. For example, in the production of the glass material, molten glass is poured into a mold and molded into a plate to produce the glass material for molding according to the present invention. The obtained glass material is appropriately cut, ground, and polished to produce a molding precursor (also referred to as a cut piece) having a size and shape suitable for molding after reheating. The cut piece is heated and softened, and molded by a known method (reheat pressing, round bar molding, extrusion molding, etc.) to produce an optical element blank that approximates the shape of the optical element. The optical element blank is annealed, and then cut, ground, polished, etc. by a known method to produce an optical element.

[0460] The optically functional surface of the fabricated optical element may be coated with an anti-reflection film, a total reflection film, or the like depending on the intended use.

[0461] According to one aspect of the present invention, an optical element made of the above optical glass can be provided. Examples of types of optical elements include lenses such as spherical lenses and aspherical lenses, prisms, and diffraction gratings. Examples of lens shapes include biconvex lenses, plano-convex lenses, biconcave lenses, plano-concave lenses, convex meniscus lenses, and concave meniscus lenses. The optical element can be manufactured by a method including a step of processing a glass molded body made of the above optical glass. Examples of processing include cutting, milling, rough grinding, fine grinding, and polishing. By using the above glass during such processing, breakage can be reduced, allowing for a stable supply of high-quality optical elements.

[0462] Second embodiment The glass material for molding according to the second embodiment is Maximum linear expansion coefficient α max and the average linear expansion coefficient α at 100 to 300°C 100-300 and the total content of SiO2 and ZrO2 [SiO2 + ZrO2] expressed in mass % satisfy the following formula (4). α max / α 100-300 ×[SiO2+ZrO2]≦264 (4)

[0463] In the glass material for molding according to the second embodiment, the maximum value of the linear expansion coefficient α max and the average linear expansion coefficient α at 100 to 300°C 100-300 and the total content of SiO2 and ZrO2 [SiO2 + ZrO2] expressed in mass % satisfy the following formula (4), preferably the following formula (5), and more preferably the following formula (5): By satisfying the following formula, a glass material for molding that has excellent stability when reheated can be obtained. α max / α 100-300 ×[SiO2+ZrO2]≦264 (4) α max / α 100-300 ×[SiO2+ZrO2]≦260 (5) α max / α 100-300×[SiO2+ZrO2]≦255 (6)

[0464] Maximum linear expansion coefficient α max and the average linear expansion coefficient α 100-300 can be controlled by adjusting the conditions for cooling the molten glass in the process of producing the glass material.

[0465] Maximum linear expansion coefficient α max and the average linear expansion coefficient α 100-300 can be measured in the same manner as in the first embodiment.

[0466] In the glass material for molding according to the second embodiment, the maximum value of the linear expansion coefficient α max and the total content of SiO2 and ZrO2, [SiO2 + ZrO2], expressed in mass%, preferably satisfies the following formula (1), more preferably satisfies the following formula (2), and even more preferably satisfies the following formula (3): From the viewpoint of obtaining a glass material for molding that has excellent stability when reheated, it is preferable that the following formula is satisfied. α max ×[SiO2+ZrO2]≦27900 (1) α max ×[SiO2+ZrO2]≦27500 ···(2) α max ×[SiO2+ZrO2]≦27000 ···(3)

[0467] Maximum linear expansion coefficient α max can be controlled by adjusting the conditions for cooling the molten glass in the process of producing the glass material.

[0468] In the glass material for molding according to the second embodiment, the properties and glass composition other than those mentioned above can be the same as those in the first embodiment. Furthermore, the production of the glass material and the production of optical elements and the like in the second embodiment can also be the same as those in the first embodiment.

[0469] Third embodiment The glass material for molding according to the third embodiment is Maximum linear expansion coefficient α max The glass material for molding is soaked at the glass transition temperature Tg, then cooled at -30°C / hr for 4 hours, and then allowed to cool. The maximum linear expansion coefficient α of the glass material obtained is max (Tg) is smaller.

[0470] In the glass material for molding according to the third embodiment, the maximum value of the linear expansion coefficient α max is the maximum value of the linear expansion coefficient α of the glass material obtained by soaking the glass material for molding at the glass transition temperature Tg, cooling it at -30°C / hr for 4 hours, and then allowing it to cool. max (Tg). However, the maximum linear expansion coefficient α max is the maximum value of the linear expansion coefficient α max (Tg) may be slightly larger than α max and α max (Tg) difference [α max (Tg)-α max ] is 10 -7 °C -1 When expressed in units of 1 to the first integer, it is preferably -9 or more, and more preferably -4 or more, 0 or more, 5 or more, 10 or more, 20 or more, 40 or more, 60 or more, 80 or more, 100 or more, 120 or more, 140 or more, 160 or more, 180 or more, 200 or more, 250 or more, and 300 or more in that order. max (Tg), and preferably α max (Tg) is about -100.

[0471] In the glass material for molding according to the third embodiment, the maximum value α max The method for measuring (Tg) is the same as in the first embodiment.

[0472] In the glass material for molding according to the third embodiment, the maximum value of the linear expansion coefficient α maxand the total content of SiO2 and ZrO2, [SiO2 + ZrO2], expressed in mass%, preferably satisfies the following formula (1), more preferably satisfies the following formula (2), and even more preferably satisfies the following formula (3): From the viewpoint of obtaining a glass material for molding that has excellent stability when reheated, it is preferable that the following formula is satisfied. α max ×[SiO2+ZrO2]≦27900 (1) α max ×[SiO2+ZrO2]≦27500 ···(2) α max ×[SiO2+ZrO2]≦27000 ···(3)

[0473] Maximum linear expansion coefficient α max can be controlled by adjusting the conditions for cooling the molten glass in the process of producing the glass material.

[0474] In the glass material for molding according to the third embodiment, the properties and glass composition other than those mentioned above can be the same as those in the first embodiment. Furthermore, the production of the glass material in the third embodiment and the production of optical elements and the like can also be the same as those in the first embodiment. [Example]

[0475] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the embodiments shown in the examples.

[0476] (Example 1-1) Glass samples having glass composition I shown in Table 1(1) were prepared by the following procedure, and the obtained glass samples were subjected to various evaluations. The results are shown in Tables 2(1) and 2(2).

[0477] [Glass sample manufacturing] First, oxides, hydroxides, carbonates, and nitrates corresponding to the glass components were prepared as raw materials. These raw materials were weighed and mixed so that the resulting optical glass would have the glass composition shown in Table 1(1). The raw materials were thoroughly mixed. The resulting blended raw materials (batch raw materials) were placed in a platinum crucible and heated at 1350°C to 1450°C for 2 hours to form a molten glass. The mixture was stirred to homogenize and refined, and then the molten glass was cast into a mold preheated to an appropriate temperature and rapidly cooled (Step 1). The cast glass was then held for 30 minutes at a holding temperature Tx, which was 25°C lower than the glass transition temperature Tg (Step 2). The glass was then cooled at a rate of −30°C / hr to a temperature 120°C lower than the holding temperature Tx of Step 2 (Step 3), and then allowed to cool to room temperature in a furnace (Step 4), yielding a glass sample. The amount of glass used was 150 g.

[0478] Here, the holding temperature Tx in step 2 was set to a value 25°C lower than the glass transition temperature Tg (unit: °C) rounded to the nearest whole number, which was used as the Tg of the glass sample. Table 2(2) shows the difference between the rounded Tg and the holding temperature Tx, which corresponds to this temperature difference. In this way, the same holding temperature Tx can be set regardless of slight variations in the measured Tg values, and multiple samples can be held at the same time, thereby improving the production efficiency of the glass of the present invention.

[0479] [Confirmation of glass composition] The content of each glass component in the obtained glass sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and it was confirmed that the composition was as shown in Table 1(1).

[0480] [Glass transition temperature Tg] The glass transition temperature Tg was measured using a differential scanning calorimeter (DSC3300SA) manufactured by NETZSCH JAPAN at a temperature rise rate of 10°C / min.

[0481] [Stability test] The obtained glass sample was checked for the absence of internal foreign matter using an optical microscope (100x magnification), and then cut and milled to obtain a specimen measuring 11 mm x 11 mm x 10.5 mm. This sample was placed in a heat treatment furnace set to a temperature 200°C higher than the Tg and heated. After 5 minutes, it was removed and cooled. After cooling, the edges of the glass sample were optically polished, and the interior of the glass sample was observed using an optical microscope (100x magnification). The number of crystals (bright spots) observed throughout the glass sample was counted and converted to the number per gram. The crystals ranged in size from 1 to 300 μm. No cracks or striae were observed in the glass sample.

[0482] [Linear expansion coefficient] The average coefficient of linear expansion of the obtained glass samples was measured in accordance with the JOGIS08 standard. The sample was a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm. With a load of 98 mN applied to the sample, it was heated at a constant rate of 4°C per minute, and the temperature and elongation of the sample were measured in 1-second intervals. Between room temperature and the yield point temperature (the temperature at which the sample yields and apparent elongation stops), the maximum value of the coefficient of linear expansion at the temperature at which the sample elongates at a maximum per unit temperature increase was defined as α. max In addition, α max The maximum value obtained by performing a moving average process on the linear expansion coefficients at 31 measurement points was used. The average value of the linear expansion coefficients at 100 to 300°C was used as the average linear expansion coefficient α 100-300 It was decided.

[0483] Maximum linear expansion coefficient α max and the maximum value α of the linear expansion coefficient of the glass when the holding temperature Tx in step 2 is the glass transition temperature. max (Tg) and the difference Q:α max (Tg)-α max was calculated.

[0484] [Average linear expansion coefficient α L ] The average linear expansion coefficient of the obtained glass samples was measured in accordance with the provisions of JOGIS16. The average linear expansion coefficient was measured using a thermomechanical analyzer (TMA4000SE) manufactured by NETZSCH JAPAN. The sample was a round bar with a length of 20 mm ± 0.5 mm and a diameter of 5 mm ± 0.5 mm. First, the sample was cooled to -80°C or below using liquid nitrogen, and after holding for 20 minutes, the measurement was started. During the measurement, a load of 98 mN was applied to the sample, and the temperature was raised to 320°C at a constant rate of 4°C per minute, while the temperature and sample elongation were measured every second. The average value of the linear expansion coefficients from -30 to 70°C was taken as the average linear expansion coefficient α L It was decided.

[0485] [Optical property measurement] The refractive indices nd, ng, nF and nC, Abbe number νd, partial dispersion ratios Pg,F and ΔPg,F of the obtained glass samples were measured. The results are shown in Tables 2(1) and 2(2).

[0486] (i) Refractive indexes nd, ng, nF, nC and Abbe number νd The refractive indices nd, ng, nF, and nC of the glass sample were measured by the refractive index measurement method of Japanese Industrial Standards JIS B 7071-1, and the Abbe number vd was calculated according to the following formula. νd=(nd-1) / (nF-nC)

[0487] (ii) Partial dispersion ratio Pg,F, ΔPg,F The partial dispersion ratios Pg,F and ΔPg,F were calculated using the refractive indices ng, nF, and nC at the g-line, F-line, and c-line, respectively, based on the following formula. Pg,F=(ng-nF) / (nF-nC) ···(13) ΔPg,F=Pg,F-(0.6483-0.001802×νd) ···(14)

[0488] [Evaluation of light transmittance] (i)λτ80 Using glass samples with thicknesses of 2.0 mm ± 0.1 mm and 10.0 mm ± 0.1 mm, spectral transmittance was measured in the wavelength range of 200 to 700 nm in accordance with JOGIS17 (Method for measuring internal transmittance of optical glass). The wavelength at which the internal transmittance of a 10 mm thickness was 80% was defined as λτ80. The results are shown in Table 2(1).

[0489] (ii) λ70 The spectral transmittance of a glass sample with a thickness of 10.0 mm±0.1 mm was measured in the wavelength range of 200 to 700 nm. The wavelength at which the external transmittance was 70% was defined as λ70. The results are shown in Table 2(1).

[0490] [specific gravity] The specific gravity was measured by Archimedes' method, and the results are shown in Table 2(1).

[0491] (Example 1-2) In producing the glass sample, a glass sample was obtained in the same manner as in Example 1-1, except that the holding temperature Tx in step 2 was set to a temperature 50° C. lower than the glass transition temperature Tg. Various evaluations were performed in the same manner as in Example 1-1.

[0492] (Examples 1-3) In producing the glass sample, a glass sample was obtained in the same manner as in Example 1-1, except that the holding temperature Tx in step 2 was set to a temperature 100° C. lower than the glass transition temperature Tg. Various evaluations were performed in the same manner as in Example 1-1.

[0493] Example 2-1 A glass sample having glass composition II shown in Table 1(1) was produced. In producing the glass sample, raw materials were blended to obtain glass composition II, and the holding temperature Tx in step 2 was set to a temperature 60°C lower than the glass transition temperature Tg, but the other conditions were the same as in Example 1-1. Various evaluations were performed in the same manner as in Example 1-1.

[0494] (Comparative Example 1-1) In producing the glass sample, a glass sample was obtained in the same manner as in Example 1-1, except that the holding temperature Tx in step 2 was set to a temperature 30° C. higher than the glass transition temperature Tg. Various evaluations were performed in the same manner as in Example 1-1.

[0495] (Comparative Example 1-2) In the production of the glass sample, a glass sample was obtained in the same manner as in Example 1-1, except that the holding temperature Tx in step 2 was set to the glass transition temperature Tg. Various evaluations were performed in the same manner as in Example 1-1. Note that the maximum value of the linear expansion coefficient in Comparative Example 1-2 was α max (Tg), and the maximum linear expansion coefficient α in Examples 1-1, 1-2, and 1-3 max Compared to.

[0496] (Comparative Examples 1-3) In the production of the glass sample, a glass sample was obtained in the same manner as in Example 1-1, except that the holding time in step 2 was 72 hours. Various evaluations were performed in the same manner as in Example 1-1. Note that, although a glass was obtained in Comparative Example 1-3, significant devitrification occurred in the stability test. Furthermore, the refractive index nd, Abbe number νd, partial dispersion ratio Pg,F, and ΔPg,F could not be measured.

[0497] (Comparative Example 2-1) In the production of the glass sample, a glass sample was obtained in the same manner as in Example 2-1, except that the holding temperature Tx in step 2 was set to the glass transition temperature Tg. Various evaluations were performed in the same manner as in Example 2-1. Note that the maximum value of the linear expansion coefficient in Comparative Example 2-1 was α max (Tg), and the maximum linear expansion coefficient α in Example 2-1 max Compared to.

[0498] (Example 3-1) A glass sample having glass composition III shown in Table 1(2) was produced. In producing the glass sample, raw materials were blended to obtain glass composition III, and the holding temperature Tx in step 2 was set to a temperature 60°C lower than the glass transition temperature Tg, but the other conditions were the same as in Example 1-1. Various evaluations were performed in the same manner as in Example 1-1.

[0499] (Example 3-2) A glass sample having glass composition III shown in Table 1(2) was produced. In producing the glass sample, raw materials were blended to obtain glass composition III, and the holding temperature Tx in step 2 was set to a temperature 100°C lower than the glass transition temperature Tg, but the other procedures were the same as in Example 1-1 to obtain the glass sample. Various evaluations were performed in the same manner as in Example 1-1.

[0500] Example 4-1 A glass sample having glass composition IV shown in Table 1(3) was produced. In producing the glass sample, raw materials were blended to give glass composition IV, and the holding temperature Tx in step 2 was set to the same temperature as the glass transition temperature Tg, but other than that, the glass sample was obtained in the same manner as in Example 1-1. Various evaluations were performed in the same manner as in Example 1-1.

[0501] (Example 4-2) A glass sample having glass composition IV shown in Table 1(3) was produced. In producing the glass sample, raw materials were blended so as to obtain glass composition IV, and the glass sample was obtained in the same manner as in Example 1-1. Various evaluations were performed in the same manner as in Example 1-1.

[0502] [Table 1(1)]

[0503] [Table 1(2)]

[0504] [Table 1(3)]

[0505] [Table 2(1)]

[0506] [Table 2(2)]

[0507] Example 3 Lens blanks were prepared by known methods using the glass samples prepared in Examples 1-1, 1-2, 1-3, 2-1, 3-1, 3-2, 4-1, and 4-2, and various lenses were prepared by processing the lens blanks by known methods such as polishing. The optical lenses produced include various lenses such as biconvex lenses, biconcave lenses, plano-convex lenses, plano-concave lenses, concave meniscus lenses, and convex meniscus lenses. By combining various lenses with lenses made of other types of optical glass, it was possible to effectively correct secondary chromatic aberration.

[0508] In the same manner, prisms were fabricated using the various optical glasses fabricated in Examples 1-1, 1-2, 1-3, 2-1, 3-1, 3-2, 4-1, and 4-2.

[0509] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0510] For example, by adjusting the composition as described in the specification for the glass compositions exemplified above, an optical glass according to one aspect of the present invention can be produced. Furthermore, it is of course possible to arbitrarily combine two or more of the items described in the specification as examples or preferred ranges.

Claims

1. A glass material for molding that satisfies either A or B below: A. When the composition has the following composition I and the maximum linear expansion coefficient α max is 925, 720 or 631, or when the composition has the following composition II and α max is 615: Table 1 A. When a sample of 11 mm x 11 mm x 10.5 mm is heat-treated for 5 minutes at a temperature 200°C higher than the glass transition temperature Tg, the number density D of crystals per 1 g of glass is less than 10 crystals / g, The maximum value α max of the linear expansion coefficient and the total content of SiO 2 and ZrO 2 [SiO 2 +ZrO 2 ] expressed in mass % satisfy the following formula (1): α max × [SiO 2 + ZrO 2 ]≦27900 (1) Contains 6 to 40 mass % of SiO 2 , Contains 0 to 5 mass % of P 2 O 5 , the total content of SiO 2 and P 2 O 5 [SiO 2 +P 2 O 5 ] is 5 to 40 mass %, the total content of SiO 2 , P 2 O 5 and B 2 O 3 [SiO 2 +P 2 O 5 +B 2 O 3 ] is 5 to 50 mass %, Contains 0 to 20 mass % of TiO 2 , the total content of Nb 2 O 5 and TiO 2 [Nb 2 O 5 +TiO 2 ] is 10 to 80 mass %, Contains 0 to 20 mass % WO 3 , The content of ZrO 2 is 2 mass% or more, The content of Bi 2 O 3 is 20 mass % or less, When α max is 925 to 615.

2. In the case of A, 2. The glass material for molding according to claim 1, wherein when a sample of 11 mm × 11 mm × 10.5 mm is heat-treated for 5 minutes at a temperature 200° C. higher than the glass transition temperature Tg, the number density D of crystals per 1 g of glass is less than 10 crystals / g.

3. TiO in mass% 2 The content of [TiO 2 ] and Nb 2 O 5 The content of [Nb 2 O 5 3. The glass material for molding according to claim 1, wherein the following formula (7) is satisfied: {5×[TiO 2 ]} / {3×[Nb 2 O 5 ]}≦3 ・・・(7)

4. In the wavelength range of 280 to 700 nm, the wavelength λτ at which the internal transmittance of a 10 mm thick glass is 80% 80 The glass material for molding according to any one of claims 1 to 3, wherein the .lambda.

5. 5. The glass material for molding according to claim 1, wherein the Abbe number νd and the partial dispersion ratio Pg, F satisfy the following formula (8): Pg,F≦-0.00286×νd+0.68700...(8)

6. A method for producing an optical element, comprising the step of heating, softening, and molding the glass material for molding according to any one of claims 1 to 5.

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