High refractive index glass

Abstract

To provide a high refractive index glass which has a high transmittance property in the visible wavelength range and has a lowest possible density.SOLUTION: A glass having a refractive index nd of 1.95 to 2.05 and a dispersion vd of 22 to less than 35 contains the following components in mass%: 4 to 12 of SiO2; 4 to 11 of B2O3; less than 10 of BaO; 30 to less than 52 of La2O3; less than 14 of Gd2O3; less than 5.5 of ZrO2; 10 to 25 of TiO2; 3 to 16 of Nb2O5; and 2.0 or less of ZnO. The sum total of the mass proportions of SiO2 and B2O3 is at least 10 mass%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a material having a high refractive index, particularly a refractive index n of 1.95 to 2.05. d and Abbe number v from 22 to less than 35 d The present invention relates to a glass having the above-mentioned formula: The glass preferably has a high transmittance in the visible wavelength range, especially in the lower visible wavelength range. The present invention also relates to the use of the glass. The glass according to the present invention can be used especially for AR glasses. Further applications are, for example, the use in the optical field as lenses or waveguides. [Background technology]

[0002] The field of the so-called "Augmented Reality" (AR) is becoming more and more important. This is understood to mean an extension of reality, especially for visually presented computer-generated information. For this purpose, special glasses, so-called AR glasses, are often used. To produce such glasses, glasses with a particularly high refractive index are required, since this increases the field of view (FoV). Furthermore, the glasses should preferably have a particularly good transmittance in the visible wavelength range. In this regard, especially in the case of high-refractive index glasses, the transmittance in particular in the lower visible wavelength range, for example in the blue range 420 nm to 490 nm, in particular at 420 nm or 460 nm, proves to be a problem. In this regard, one also speaks of the so-called "UV edge" of the glasses. If the UV edge is shifted too far into the visible range or does not rise steeply enough, the transmittance properties are not good in the lower visible wavelength range. Furthermore, it has proven difficult to provide glasses with a particularly high refractive index in the entire visible range (in particular 380 nm to 750 nm). Therefore, for example, a refractive index n of 2.001 d However, glasses are known that have a refractive index of at least 2.000 at other wavelengths in the visible range.

[0003] In the past, glasses based especially on niobium phosphates were used. However, these glasses are very problematic in production, because in the already reducing phosphoric acid system, the loss of oxygen, especially due to the high melting and fining temperatures, leads to a lower oxidation state of Nb than V and thus to a coloration ranging from dark brown to black. Furthermore, these glasses, like the lanthanum borate or borosilicate systems, not only tend to crystallize at the interfaces, but also show very fast crystal growth, which makes subsequent cooling (stress cooling or adjustment of the refractive power) potentially critical for the pre-nucleated glass. Furthermore, the glasses are relatively brittle, which makes them difficult to polish into thin wafers.

[0004] In particular, refractive indices between 1.93 and 2.08 over the entire visible range of the spectrum and / or refractive indices n d A glass having a refractive index of 0.1 to 0.5 should be provided. The glass is preferably characterized by good transmission properties, especially also in the lower visible wavelength range, for example at 420 nm and / or 460 nm. Furthermore, the batch costs should remain reasonable. The glass should have a good ability to be finished without streaks. Furthermore, the glass should be able to be finished into wafers with good yields. The glass should be particularly well hot-formable and well processable. The glass should have the lowest possible density despite a high refractive index. This can increase the wearing comfort of the AR glasses in particular. Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to provide a glass which overcomes the drawbacks from the prior art. Said object is achieved by the subject matter of the claims. [Means for solving the problem]

[0006] Description of the invention In one embodiment, the present invention provides a method for producing a refractive index nd 1.95 to 2.05, and variance v d A glass having 22 to 35% by mass of the following components: [Table 1] where SiO 2 and B. 2 O 3 is at least 10% by mass.

[0007] In a further aspect, the present invention provides a method for producing a fluororesin having a refractive index n d 1.95 to 2.05, and advantageously a variance v d A glass having 22 to 35% by mass of the following components: [Table 2] where SiO 2 and B. 2 O 3 is at least 10% by mass.

[0008] In a further aspect, the present invention provides a fluororesin having a refractive index of 1.93 to 2.08 and a dispersion v d A glass having 22 to 35% by mass of the following components: [Table 3] where SiO 2 and B. 2 O 3 is at least 10% by mass.

[0009] According to the invention, the glass has a refractive index n of 1.95 to 2.05, preferably 1.97 to 2.02, particularly preferably 1.98 to 2.01, and further particularly preferably 1.99 to 2.01. d has.

[0010] Refractive index nd is known to those skilled in the art and specifically denotes the refractive index at a wavelength of about 587.6 nm (the wavelength of the d line of helium). d It is known to those skilled in the art how to identify

[0011] Preferably, the refractive index is determined using a refractometer, in particular a V-block refractometer. In particular, a square or nearly square base sample (e.g., having dimensions of about 20 mm x 20 mm x 5 mm) may be used. When measuring with a V-block refractometer, the sample is usually placed in a V-shaped block prism with a known refractive index. The refraction of the incident light beam depends on the difference between the refractive index of the sample and the refractive index of the V-block prism, so that the refractive index of the sample can be determined. The measurement is preferably performed at a temperature of 22°C.

[0012] The refractive index depends on the wavelength of light, and at various wavelengths, e.g., n d n can be specified at about 587.6 nm, nF at about 486 nm, and nC at about 656 nm. Preferably, the glass has a refractive index between 1.93 and 2.08 over the entire visible range of the spectrum (especially between 380 nm and 750 nm).

[0013] The refractive index value nF indicates the refractive index at a wavelength of about 486 nm. The refractive index nF of the glass of the present invention is preferably in the range of 1.96 to 2.08, for example, 1.98 to 2.06, 1.99 to 2.05, or 2.00 to 2.04.

[0014] The refractive index value nF indicates the refractive index at a wavelength of about 656 nm. The refractive index nC of the glass of the present invention is preferably in the range of 1.93 to 2.04, for example 1.95 to 2.03, or 1.96 to 2.02.

[0015] The glass has a dispersion v of 22 to less than 35, preferably 24 to 30, and particularly preferably 25 to 28. d has.

[0016] According to the invention, the glass has an internal transmittance TI of at least 80%, preferably at least 85%, preferably at least 90%, more preferably at least 91%, more preferably at least 92%, more preferably at least 93%, more preferably at least 94%, more preferably at least 95%, more preferably at least 96%, more preferably at least 97%, said internal transmittance being measured at a wavelength of 460 nm and a sample thickness of 10 mm.

[0017] The internal transmittance or internal transmission rate can be measured in a manner well known to the person skilled in the art, for example according to DIN 5036-1:1978. In this specification, the statements about the internal transmittance refer to a sample thickness of 10 mm. The statement of "sample thickness" does not mean that the glass has this thickness, but merely describes the thickness to which the statements about the internal transmittance refer.

[0018] Unless otherwise stated or apparent to one of ordinary skill in the art, measurements described herein are made at 20° C. and 101.3 kPa pressure.

[0019] The density of the glass according to the invention is preferably 4.40 g / cm 3 ~5.30g / cm 3 , and more preferably 4.45 g / cm 3 ~5.20g / cm 3 , and more preferably 4.50 g / cm 3 ~5.10g / cm 3 In some embodiments, the density of the glass is in the range of 5.05 g / cm 3 Less than 5.00 g / cm 3 Less than 4.95 g / cm 3 Less than 4.90 g / cm 3 Less than 4.85 g / cm 3 Less than 4.80 g / cm 3 Less than 4.70 g / cm 3 Less than 4.60 g / cm 3 is less than.

[0020] It is known that the density of a glass increases with an increase in the refractive index. However, the glasses according to the invention are particularly characterized by a relatively low density despite their high refractive index. d The ratio to is preferably 2.10 to 2.60 g / cm 3 , and more preferably 2.25 to 2.55 g / cm 3 , more preferably 2.30 to 2.50 g / cm 3 The range of density and refractive index n d The ratio of the density value (g / cm 3 ) with the refractive index n d It is particularly preferable to divide the refractive index n d The ratio to is 2.60g / cm 3 less than 2.55 g / cm 3 less than 2.50 g / cm 3 less than 2.45 g / cm 3 less than 2.40 g / cm 3 less than 2.35 g / cm 3 is less than.

[0021] The glasses of the invention preferably have a high transmission in the visible range, especially also in the lower visible wavelength range, for example at 420 nm and / or 460 nm, and thus, despite the high refractive index characteristic, preferably have a relatively low UV edge.

[0022] Preferably, the internal transmittance TI of the glass is at least 25%, more preferably at least 30%, more preferably at least 40%, more preferably at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, more preferably at least 87.5%, and more preferably at least 90%, measured at a wavelength of 420 nm and a sample thickness of 10 mm. In some embodiments, the internal transmittance TI of the glass is at most 99%, at most 98%, at most 95%, or at most 92.5%, measured at a wavelength of 420 nm and a sample thickness of 10 mm.

[0023] Preferably, the internal transmittance TI of the glass is at least 63%, more preferably at least 65%, more preferably at least 70%, more preferably at least 75%, more preferably at least 80%, more preferably at least 85%, more preferably at least 87.5%, more preferably at least 90%, more preferably at least 91%, more preferably at least 92%, more preferably at least 93%, more preferably at least 94%, more preferably at least 95%, more preferably at least 96%, and more preferably at least 97% when measured at a wavelength of 460 nm and a sample thickness of 10 mm. In some embodiments, the internal transmittance TI of the glass is at most 99.99%, at most 99.9%, at most 99%, or at most 98% when measured at a wavelength of 460 nm and a sample thickness of 10 mm.

[0024] If the glass transition temperature Tg is too high, the subsequent cooling takes a long time. However, Tg is also a measure for chemical durability and hardness (the higher the Tg, the more stable the network, and therefore the harder and more chemically durable the glass). High chemical durability is good, but on the other hand too high hardness is also expensive, because grinding and polishing take a long time and must be done very carefully so as not to generate too many microcracks. Therefore, the glass transition temperature Tg of the glass according to the invention is preferably in the range of 650°C to 800°C, more preferably 680°C to 760°C, more preferably 690°C to 750°C.

[0025] Viscosity is 10 1 The temperature T1 in dPas is preferably in the range of 1100° C. to 1250° C., more preferably in the range of 1150° C. to 1200° C., or in the range of 1100° C. to 1150° C., or in the range of 1200° C. to 1250° C. Thus, the glass composition of the present invention allows a particularly low melting temperature.

[0026] Viscosity is 10 4 The temperature T4 in dPas is preferably in the range of 875°C to 1025°C, more preferably in the range of 925°C to 975°C, or in the range of 875°C to 925°C, or in the range of 975°C to 1025°C.

[0027] Viscosity is 10 7.6 The softening temperature T7.6 in dPas (English "softening temperature") is preferably in the range of 750°C to 900°C, more preferably 800°C to 850°C, or 750°C to 800°C, or 850°C to 900°C.

[0028] The crystallization temperature TK is preferably in the range of 1000° C. to 1200° C., more preferably 1025° C. to 1175° C., and still more preferably 1050° C. to 1150° C., or 1025° C. to 1125° C., or 1075° C. to 1175° C. The viscosity at TK is preferably in the range of 10 to 100 dPas.

[0029] The viscosity of the glass can be determined, for example, using a rotational viscometer according to DIN ISO 7884-2:1998-2. The temperature dependence of the viscosity can be determined using the VFT curve (Vogel-Fulcher-Tammann equation). The softening temperature can be determined using a spindle viscometer according to ISO 7884-2.

[0030] The glasses of the invention preferably have a coefficient of thermal expansion (in English "coefficient of thermal expansion (CTE)") in the temperature range 20°C to 300°C (CTE(20,300)) ranging from 6.7 to 10.0 ppm / K, more preferably from 7.0 to 9.7 ppm / K, more preferably from 7.3 to 9.4 ppm / K, more preferably from 7.6 to 9.1 ppm / K, more preferably from 7.8 to 8.8 ppm / K, more preferably from 7.9 to 8.6 ppm / K, more preferably from 8.0 to 8.5 ppm / K. The CTE should be well matched to the coating, where particularly very high CTEs often cause problems, since polymers often do not have a linear CTE progression in this range, but rather a more abrupt one. If the glass has an incompatible CTE, cracks or delamination of the layer may occur. For this reason, among others, the above CTE values ​​are preferred.

[0031] Preferably, the glass comprises the following components in mass %: [Table 4] where SiO 2 and B. 2 O 3 The total mass ratio of is in the range of 12 to 21, and preferably SiO 2 The proportion of B 2 O 3 %, preferably more than that.

[0032] More preferably, the glass has the following components in mass %: [Table 5] where SiO 2 and B. 2 O 3 The total mass ratio of is in the range of 13 to 20, and preferably SiO 2 The proportion of B 2 O 3 %, preferably more than that.

[0033] The glass of the present invention is SiO 2 The content is 4 to 12 mass %, preferably 5 to 11 mass %. 2 is a glass former. The oxide contributes significantly to the chemical durability, but also increases the processing temperature. If it is used in too large an amount, the refractive index according to the invention cannot be achieved. Particularly preferred is SiO 2 The proportion is preferably in the range of 6.5 to 10.5 mass %, more preferably 7 to 10 mass %, and even more preferably 7.5 to 9.5 mass %.

[0034] B 2 O 3 has proven to be particularly suitable for achieving low melting temperatures. However, due to its corrosiveness, especially towards the material of the melting bath, B 2 O 3 The content of B is limited. 2 O 3 The content is 4 to 11 mass %, preferably 4.5 to 10 mass %, more preferably 5 to 9 mass %, and further preferably 5.5 to 8.5 mass %.

[0035] SiO 2 and B. 2 O 3 If the sum of the mass fractions of SiO is very large, this has a negative effect on the refractive index. 2 and B. 2 O 3 Since SiO is needed as a network former, its proportion must not be very small. 2 and B. 2 O 3 The total mass proportion of is at least 10 mass%. Preferably, SiO2 and B. 2 O 3 The total mass proportion of the above is preferably 11 to 22 mass%, more preferably 12 to 21 mass%, even more preferably 13 to 20 mass%, and still more preferably 13.5 to 19 mass%.

[0036] In some embodiments, SiO 2 The mass ratio of B 2 O 3 The mass fraction of SiO 2 For example, B 2 O 3 However, in the case of B, the fireproofing material is not attacked. 2 O 3 is favorable for melting behavior. SiO 2 Percentage of B 2 O 3 Mass ratio of SiO 2 / B 2 O 3 ) is preferably in the range of 0.85 to 2.0, preferably 0.95 to 1.9, more preferably 1.0 to 1.8, and even more preferably 1.05 to 1.75. In a preferred embodiment, SiO 2 The mass ratio of B 2 O 3 and particularly preferably more than this mass proportion.

[0037] SiO 2 Percentage of B 2 O 3 The mass to volume ratio can be advantageously used to appropriately adjust the melting temperature and corrosivity of the melt.

[0038] Preferably, the La in the glass according to the invention 2 O 3 , Nb 2 O 5 , TiO 2 and ZrO 2 The total proportion of is 80 mass% or less, preferably 78 mass% or less, more preferably 76 mass% or less, and even more preferably 75 mass% or less. 2 O 3, Nb 2 O 5 , TiO 2 and ZrO 2 In some embodiments, the total proportion of La is in the range of 62% by mass to 80% by mass. 2 O 3 , Nb 2 O 5 , TiO 2 and ZrO 2 The total proportion of La is in the range of 68% by mass to 80% by mass, preferably in the range of 70% by mass to 78% by mass, and particularly preferably in the range of 71% by mass to 76% by mass. 2 O 3 , Nb 2 O 5 , TiO 2 and ZrO 2 The total proportion of these components is in the range of 62 to 66% by mass, preferably 63 to 65% by mass. A high proportion of these components is advantageous for achieving a particularly high refractive index. However, it may also increase the tendency to crystallize, so it may be advantageous to limit their content.

[0039] La 2 O 3 , Nb 2 O 5 , TiO 2 and ZrO 2 The percentage of total SiO 2 and B. 2 O 3 The mass ratio to the total proportion of is preferably in the range of 3.4 to 5.6, more preferably 3.8 to 5.5, and particularly preferably 4.0 to 5.1.

[0040] BaO, La 2 O 3 , Nb 2 O 5 , TiO 2 and ZrO 2 The percentage of total SiO 2 and B. 2 O 3 The mass ratio to the total proportion of is preferably in the range of 3.9 to 5.8, more preferably 4.0 to 5.7, and particularly preferably 4.3 to 5.8.

[0041] La 2 O 3 has a proportion of 30 to less than 52 mass % and is one of the main components of the glass according to the present invention. 2 O 3 SiO 2 and B. 2 O 3 Together with TiO, a dense glass network is formed. 2 is inserted. 2 O 3 is stable, is not redox sensitive, and is comparable in price and availability to Gd 2 O 3 and Nb 2 O 5 It is also more advantageous in some embodiments. 2 O 3 The proportion of La is in the range of 35 to 51 mass%, more preferably 37 to 50 mass%, particularly preferably 39.5 to 49 mass%, more preferably 40 to 48 mass%, and even more preferably 42 to 47 mass%. 2 O 3 Increasing the proportion of La has a detrimental effect on the refractive index. 2 O 3 Also increases the tendency for crystallization. 2 O 3 The proportion is in the range of 30 to 35 mass %, preferably 30.5 to 33 mass %.

[0042] La 2 O 3 Nb 2 O 5 , TiO 2 and ZrO 2 In view of the fact that the redox stability or crystallization stability is higher than that of La, in some embodiments of the glass according to the present invention, 2 O 3 The proportion of La 2 O 3 , TiO 2 , Nb 2 O 5 and ZrO 2On the other hand, it is advantageous to adjust the refractive index to a certain minimum ratio to the sum of the proportions of La 2 O 3 The ratio of La should not be too high. 2 O 3 The proportion of La 2 O 3 , TiO 2 , Nb 2 O 5 and ZrO 2 It has proven to be advantageous for the mass ratio to the sum of the proportions of in the range from 0.42 to 0.65, preferably from 0.45 to 0.64, preferably from 0.47 to 0.63, particularly preferably from 0.59 to 0.64.

[0043] The glass according to the present invention contains Nb 2 O 5 In addition to having a large effect on the refractive index, Nb is contained in the glass in an amount of 3 to 16 mass %, preferably 5 to 13 mass %, and particularly preferably 6.5 to 12.5 mass %. 2 O 5 It also has a positive effect on the glass density. This component can be used to reduce the density. However, there may be a tendency towards oxygen loss and the formation of lower oxidation numbers and therefore strong coloration.

[0044] La 2 O 3 and Nb 2 O 5 The total proportion of La is preferably in the range of 35 to 65 mass%, more preferably 45 to 62 mass%, and still more preferably 48 to 60 mass%. 2 O 3 and Nb 2 O 5 The total proportion of La is preferably in the range of 35 to 45 mass%, more preferably 37 to 42 mass%. 2 O 3 and Nb 2 O 5 The sum of the proportions is at least 50% by weight, very particularly preferably at least 57.5% by weight.

[0045] The glass of the present invention is TiO 2 In some embodiments, TiO 2 The proportion of TiO is 12 to 20 mass%, more preferably 13 to 19.5 mass%, and still more preferably 14 to 19 mass%. 2 The proportion of TiO is preferably 19 to 25 mass%, particularly preferably 21.5 to 24 mass%. 2 In particular, TiO contributes to the high refractive index and also helps to keep the density relatively low. 2 It is advantageous to limit the proportion of since, as a nucleating agent, it can contribute to crystal growth, which makes subsequent hot working, e.g. pressing, difficult.

[0046] ZrO 2 is TiO 2 In contrast to ZrO, it does not tend to form the less colored oxidation states. 2 The solubility and rate of dissolution are limited by the high percentage of ZrO 2 is disadvantageous because a higher temperature is required for complete dissolution, which in turn has a negative effect on the transmittance. 2 The purity of ZrO is not very high (especially due to contamination with Fe). 2 An upper limit is set for the content of ZrO in the glass according to the invention. 2 The proportion of is less than 5.5% by weight, preferably less than 5% by weight, particularly preferably less than 4.5% by weight, preferably less than 3.5% by weight. 2 The proportion of ZrO is 0.5 to 5 mass%, more preferably 0.5 to 4.5 mass%, more preferably 1.0 to 4.0 mass%, and even more preferably 1.5 to 3.5 mass%. In order to suppress possible crystal growth, ZrO 2 It is also advantageous to limit the proportion of ZrO 2 Not included.

[0047] TiO 2 and ZrO 2In particular, TiO contributes to the high refractive index. 2 On the other hand, TiO also contributes to the relatively low density. 2 and ZrO 2 The proportion of TiO should not be too large, especially with regard to solubility, nucleation, and crystallization. 2 and ZrO 2 The total proportion of TiO is preferably in the range of 14 to 30 mass%, more preferably 15 to 27.5 mass%, and still more preferably 17.5 to 22 mass%. 2 and ZrO 2 The sum of the proportions is even at least 24% by weight.

[0048] TiO 2 and ZrO 2 The total proportion of TiO 2 , ZrO 2 , Nb 2 O 5 , La 2 O 3 , Gd 2 O 3 and Y 2 O 3 It has been found to be advantageous for the ratio of the proportions to the sum to be in the range of 0.20 to 0.36, preferably 0.21 to 0.27.

[0049] Due to the tendency to crystallize, TiO in the glass 2 The possible proportion of TiO 2 As its Ti(IV) form, it also absorbs in the blue wavelength range, while Nb(V) absorbs in the UV. However, reduced Nb 2 O 5 is the reduced TiO 2 This causes significantly more absorption in the visible range than La 2 O 3 is stable and not redox sensitive. Therefore, on the one hand, TiO 2 On the other hand, an upper limit is set for the proportion of TiO in order to prevent the UV absorption of the glass from being shifted too far into the visible range in the case of fully oxidized components. 2 High n dIt is advantageous to take advantage of the contribution of La and the contribution of low density. 2 O 3 and Nb 2 O 5 ZrO also contributes a high refractive index, stabilizes the network, and keeps the UV transmittance in the high range as long as they remain oxidized. 2 , La 2 O 3 and Nb 2 O 5 The total proportion of TiO 2 Mass ratio of ZrO to 2 , La 2 O 3 , Gd 2 O 3 and Y 2 O 3 The total proportion of TiO 2 and Nb 2 O 5 It has proven advantageous to target the weight ratio of the proportions to the sum of the proportions, in particular to set a lower limit.

[0050] La 2 O 3 , Nb 2 O 5 and ZrO 2 The total proportion of TiO 2 The mass ratio of La 2 O 3 +Nb 2 O 3 +ZrO 2 ) / TiO 2 In the case of the glass of the present invention, La is preferably in the range of 1.5 to 5. 2 O 3 , Nb 2 O 5 and ZrO 2 The total proportion of TiO 2 The mass ratio of La 2 O 3 +Nb 2 O 3 +ZrO 2 ) / TiO 2) is preferably in the range of 2 to 4.6, preferably 2.5 to 4.4, and particularly preferably 2.8 to 4.2. 2 O 3 , Nb 2 O 5 and ZrO 2 The total proportion of TiO 2 The mass ratio of La 2 O 3 +Nb 2 O 3 +ZrO 2 ) / TiO 2 ) is preferably in the range of 1.5 to 2.0, particularly preferably 1.7 to 1.9.

[0051] ZrO 2 , La 2 O 3 , Gd 2 O 3 and Y 2 O 3 The total proportion of TiO 2 and Nb 2 O 5 In the case of the glass of the present invention, the mass ratio of ZrO to the total proportion is preferably in the range of 1.3 to 2.5. 2 , La 2 O 3 , Gd 2 O 3 and Y 2 O 3 The total proportion of TiO 2 and Nb 2 O 5 The mass ratio of ZrO to the total proportion is preferably in the range of 1.5 to 2.5, preferably 1.6 to 2.4. 2 , La 2 O 3 , Gd 2 O 3 and Y 2 O 3 The total proportion of TiO 2 and Nb 2 O 5 The mass ratio of the above to the total proportion is preferably in the range of 1.3 to 1.5.

[0052] color, n d From the above considerations of the contribution of TiO, the contribution of density, and the crystallization, 2 and Nb 2 O 5 It is also advantageous to target the ratio of the proportions of SiO 2 The composition can be chosen to be particularly stable, so that the range of refractive powers can be variably adjusted by simply increasing or decreasing

[0053] Preferably, TiO 2 Nb 2 O 5 The mass ratio of Nb 2 O 5 and La 2 O 3 The ratio of the proportions to the total is in the range of 0.02 to 0.08, preferably 0.03 to 0.07, and particularly preferably 0.035 to 0.065.

[0054] Preferably, La 2 O 3 and Nb 2 O 5 The total proportion of TiO 2 and ZrO 2 The mass ratio of the above to the total proportion is in the range of 1.3 to 3.5, preferably 2.0 to 3.3, and particularly preferably 2.3 to 2.1.

[0055] Nb 2 O 5 and ZrO 2 The total proportion of Nb is preferably in the range of 7 to 17 mass%, more preferably 8 to 15 mass%, and even more preferably 9 to 16 mass%. 2 O 5 and ZrO 2 It is advantageous to set an upper limit on the total proportion of ZrO, because ZrO is a component that is particularly difficult to dissolve. 2 A high proportion of Nb 2 O 5 This can be particularly problematic in relation to Nb 2 O 5 Especially at interfaces, e.g. ZrO2 This is because crystallization occurs on nuclei. During repressing, lowering or post-cooling, this can lead to uncontrolled growth of very large crystals in the body, which can even cause cracks in the casting. During lowering, and worse, cooling, there is also the risk of a thick crystalline layer forming, which is extremely difficult to remove without destruction.

[0056] The glass composition of the present invention is therefore based on a balance of the most diverse, sometimes opposing, effects. If the proportion of non-coloring components is too high, this can have a detrimental effect on the stability of the glass. 2 and Nb 2 O 5 The proportion of TiO is preferably also very high, and here too attention must be paid to the crystallization process. 2 is cheap and has a positive effect on the refractive index, but is unfavorable with respect to UV absorption. Therefore, further sums and ratios are provided, which are described below, and which lead to particularly advantageous glasses.

[0057] Preferably Nb 2 O 5 and ZrO 2 The total mass ratio of TiO 2 Particularly preferably, the mass ratio of Nb 2 O 5 and ZrO 2 The total proportion of TiO 2 Mass ratio of Nb 2 O 5 +ZrO 2 ) / TiO 2 is <1, preferably less than 0.9, preferably less than 0.8, preferably less than 0.7, and preferably in the range of 0.5 to 0.98, preferably 0.6 to 0.95. 2 O 5 and ZrO 2 The total proportion of TiO 2 Mass ratio of Nb 2 O 5 +ZrO 2 ) / TiO 2is in the range of 0.35 to 0.5.

[0058] La 2 O 3 , TiO 2 The total proportion of La and BaO is preferably in the range of 55 to 70 mass%, more preferably 60 to 68 mass%, and particularly preferably 61 to 66 mass%. 2 O 3 , TiO 2 If the sum of the proportions of BaO and CdO is selected accordingly, a glass is obtained which has good meltability at relatively low melting temperatures as well as a refractive index in the target range according to the invention.

[0059] In some embodiments, La 2 O 3 , Nb 2 O 5 and ZrO 2 On the one hand, the total mass fraction of ZrO is adjusted to a desired value, while the melting temperature is relatively low, especially ZrO 2 On the other hand, it ensures sufficient melting of Nb 2 O 5 It is advantageous to ensure sufficient redox stability of the

[0060] Accordingly, in a preferred embodiment, La 2 O 3 , Nb 2 O 5 and ZrO 2 The total proportion of La is preferably in the range of 55 to 75 mass%, more preferably 57.5 to 72.5 mass%, and still more preferably 60 to 70 mass%. 2 O 3 , Nb 2 O 5 and ZrO 2 The sum of the proportions is at least 62.0% by weight, or even at least 64.0% by weight.

[0061] Preferably, TiO 2 Percentage of ZrO 2 Mass ratio of TiO 2 / ZrO 2) is at least 4, preferably at least 4.5, at least 5, at least 5.2. In some embodiments, the ratio is preferably at least 6, preferably at least 7, preferably at least 8, or even at least 9. The corresponding mass ratios are ZrO 2 It has been found to be advantageous to avoid melting problems of the

[0062] Preferably, TiO in proportion to BaO 2 Mass ratio of BaO to TiO 2 ) is in the range of 0.13 to 0.35, preferably 0.16 to 0.33. Here, it is advantageous to set an upper limit for said ratio, since otherwise an undesirable decrease in the refractive index may occur. On the other hand, the above mentioned lower limit should also not be exceeded, since otherwise the TiO 2 This is because sufficient stabilization of the ion exchange rate can no longer be ensured.

[0063] The glass of the present invention contains Gd 2 O 3 The content is less than 14% by mass, preferably 3 to 12% by mass, more preferably 4 to 10% by mass, and preferably 4.5 to 9% by mass. 2 O 3 can adversely affect the stability of the glass.

[0064] The glass of the present invention is Y 2 O 3 Preferably, Y 2 O 3 The proportion of Y is in the range of 0 to 5 mass %, preferably 0.1 to 2 mass %, and more preferably 0.5 to 1.5 mass %. 2 O 3 Not included. High percentage of Y 2 O 3 can adversely affect the stability of the glass.

[0065] The glass of the present invention may contain BaO. BaO can lower the melting temperature, thereby reducing the melting temperature of other glass components, especially TiO. 2and Nb 2 O 5 Therefore, BaO can prevent or reduce the decrease in the oxidation number of TiO in the glass. 2 and Nb 2 O 5 On the other hand, however, a high BaO content may adversely affect the refractive index. The BaO content is in the range of 0 to less than 10% by mass, preferably from more than 0% to 9% by mass, more preferably from 1 to 9% by mass, and particularly preferably from 2 to 8.5% by mass. In some embodiments, the BaO content is in the range of 1 to 6.5% by mass, preferably from 2 to 6% by mass. In some embodiments, the BaO content is in the range of 5 to 9.5% by mass, preferably from 6 to 9% by mass. Some embodiments are free of BaO.

[0066] The glass of the present invention contains, in particular, HfO 2 Preferably, HfO 2 The proportion of HfO is in the range of 0 to 1 mass %, for example, 0.05 to 0.4 mass %, or 0.1 to 0.25 mass %. 2 is usually not a problem. Nevertheless, some embodiments may use HfO 2 Not included.

[0067] The glass of the present invention is preferably made of alkali metal oxides, particularly Li 2 O. However, preferably the glass is free of alkali metal oxides. Preferably, Li 2 The proportion of O is in the range of 0 to 0.5 mass%, for example, 0.05 to 0.2 mass%. 2 O is used as little as possible or in small amounts, since it is known to be corrosive to ceramic bath and crucible materials and can further lead to clouding of the glass and adverse crystal formation. 2 Contains no O.

[0068] The glass of the present invention may contain ZnO. Preferably, the proportion of ZnO is 2.0% by weight or less, preferably 1.5% by weight or less, more preferably 1% by weight or less, or 0.5% by weight or less. ZnO reduces the refractive power of the glass and can adversely affect the physical properties of the glass. Therefore, preferably, the glass is free of ZnO.

[0069] In one embodiment, the glass is at least 95.0% by weight, in particular at least 98.0% by weight, or at least 99.0% by weight, of SiO 2 , B 2 O 3 , La 2 O 3 , Gd 2 O 3 , Nb 2 O 5 , TiO 2 and ZrO 2 or preferably SiO 2 , B 2 O 3 , La 2 O 3 , Gd 2 O 3 , Nb 2 O 5 , TiO 2 , ZrO 2 and BaO. In one embodiment, the glass is essentially entirely composed of SiO 2 , B 2 O 3 , La 2 O 3 , Gd 2 O 3 , Nb 2 O 5 , TiO 2 , ZrO 2 and HfO 2 or SiO 2 , B 2 O 3 , La 2 O 3 , Gd 2 O 3 , Nb 2 O 5 , TiO 2 , ZrO2 , HfO 2 and BaO.

[0070] Preferably, the glass of the invention is free of one or more elements selected from MgO, CaO and SrO. Particularly preferably, the glass is free of MgO, CaO and SrO. These components reduce the refractive power and destabilize the glass. The same applies to Al 2 O 3 Therefore, preferably the glass is Al 2 O 3 Not included.

[0071] Preferably, the glass is WO 3 , Ta 2 O 5 and / or GeO 2 Particularly preferably, the glass is free of one or more of the components of WO 3 , Ta 2 O 5 and GeO 2 The presence of these components significantly increases batch costs. 2 O 5 and W.O. 3 increases the density of the glass.

[0072] The glass melt can be refined using conventional fining agents. However, since the glass can be melted especially at temperatures below 1300° C. and, due to its low viscosity, fining at rather moderate temperatures is also possible, it is possible to use, for example, Sb for UV transmission. 2 O 3 , As 2 O 3 and / or SnO 2 The Sb content can be reduced (e.g. to <0.1% by weight) or avoided (pure physical fining). 2 O 3 , As 2 O 3 and SnO 2can be used as fining agents. They are used only in small amounts. In particular arsenic and antimony are under discussion due to their health risks. The glass can be fined without the use of chemical fining agents. Optionally, the glass can have one or more of the following components with a fining action, in the proportions stated in weight percent: Sb 2 O 3 0.0~0.5 As 2 O 3 0.0~0.5 SnO 2 0.0~0.5.

[0073] SnO 2 Fining with SnO requires relatively high temperatures. 2 The glass of the present invention preferably contains SnO 2 Not included.

[0074] Sb 2 O 3 has been found to be less effective for fining and the absorption of Sb in the glass can worsen the UV edge. Therefore, it is preferred to use Sb 2 O 3 The glass of the present invention preferably contains Sb 2 O 3 Not included.

[0075] As 2 O 3 In particular, the glass of the present invention is preferably free of As 2 O 3 Not included.

[0076] In embodiments of the present invention, sulfates can be used as fining agents. However, sulfate sources often contribute iron, which can be accompanied by a deterioration in transmittance. Therefore, sulfate sources are preferably avoided. The glasses of the present invention are preferably sulfate-free.

[0077] As 2 O 3 In addition, both sulfate and N2 It is not effective against air bubbles. 2 In order to prevent bubbles from forming, for example, an inert gas atmosphere, particularly preferably CO 2 Or use argon, N 2 can be kept away from the melt surface.

[0078] The glasses according to the invention are preferably free of absorbing components, in particular free of components with absorption in the visible range. Particularly preferably, the glasses according to the invention are free of Fe 2 O 3 Not included.

[0079] Preferably, the glass is made of phosphate (P 2 O 5 ) is free, since it significantly reduces the melt and therefore significantly increases the oxygen demand of the melt. Preferably, the glass is essentially free of one or more elements selected from lead, bismuth, cadmium, nickel, platinum, arsenic and antimony, particularly preferably free of all elements.

[0080] When a glass is described herein as being free of a component or not containing a particular component, it means that this component may be present in the glass at most as an impurity. This means that they are not added in an essential amount. According to the present invention, an essential amount is an amount less than 200 ppm, preferably less than 100 ppm, preferably less than 50 ppm, and most preferably less than 10 ppm (m / m).

[0081] The proportion of platinum is preferably particularly low, since platinum particularly reduces the transmittance of the glass, preferably the proportion of platinum is less than 5 ppm, more preferably less than 3 ppm, more preferably less than 1 ppm, more preferably less than 50 ppb, more preferably less than 20 ppb.

[0082] In one aspect, the present invention relates to a glass article comprising or consisting of the glass described above. The glass article may have a variety of forms. Optionally, the article is Glasses for spectacles, in particular glasses for spectacles made of wafer stacks Wafers, in particular wafers having a maximum diameter of 5.0 cm to 40.0 cm; Lenses, in particular spherical lenses, prisms or aspherical lenses, and / or Optical waveguides, in particular fibres or plates It has the following form.

[0083] In a further aspect, the invention relates to the use of the glasses or glass articles described herein in AR glasses, wafer level optics, optical wafer applications, or conventional optics. Alternatively or additionally, the glasses or glass articles described herein can be used as wafers, lenses, spherical lenses, or optical waveguides.

[0084] The present invention also relates to a method for producing a glass or glass article according to the invention, said method comprising the steps of: melting the glass raw materials; Optionally, forming a glass article from the glass melt; Glass cooling stage Includes.

[0085] The melting of the frits can be carried out at a relatively low melting temperature based on the glass composition according to the invention. A relatively low melting temperature is advantageous in order not to reduce the oxygen content of the batch too much, which may otherwise lead to a brown coloration due to niobium or a strong yellow coloration due to reduced titanium. Preferably, the melting of the frits is carried out at a melting temperature of less than 1400°C, more preferably less than 1350°C, even more preferably less than 1330°C.

[0086] The production method according to the invention may also include a fining step. Preferably, the fining temperature is also relatively low, in particular below 1550° C., more preferably below 1450° C., more preferably below 1400° C., more preferably below 1350° C. Pure physical fining, i.e. without the addition of fining agents, is preferred.

[0087] Preferably, the fining temperature is no more than 100° C. above the melting temperature, preferably no more than 50° C. above the melting temperature.

[0088] Preferably O 2 Bubbling and O 2 Due to the preferred low process temperature, the melt is 2 There is enough O to retain the highest oxidation states of, for example, Nb(V) or Ti(IV) required for the UV edge without the addition of O. 2 Furthermore, Pt does not enter the glass.

[0089] The cooling of the glass is preferably carried out at a cooling rate in the range of 1 K / h to 20 K / h, more preferably 1.15 K / h to 15 K / h, and even more preferably 1.3 K / h to 10 K / h. Low cooling rates are particularly advantageous in order to reduce or avoid stresses. [Brief description of the drawings]

[0090] [Figure 1] FIG. 2 is a plot of the ratio of the mass fractions of TiO2 and Nb2O5 against the sum of the mass fractions of La2O3 and Nb2O5 for glasses according to the invention. EXAMPLES

[0091] Exemplary compositions shown in the table below in weight percent were melted and their properties investigated.

[0092] Table 1: "High lanthanum variants" [Table 6-1]

[0093] [Table 6-2]

[0094] The example glasses have a high refractive index and low density. Examples 1-8 also have high internal transmittance.

[0095] FIG. 1 shows the TiO 2 and Nb 2 O 5 The ratio of the mass proportions of La 2 O 3 and Nb 2 O 5 The glass according to the invention is depicted as a point along the line and has a high refractive index and a relatively low density. 2 Nb 2 O 5 has a high mass ratio to La 2 O 3 and Nb 2 O 5 The glasses with a lower total mass fraction of TiO 2 Nb 2 O 5 It is the case that the glass has a lower density than a glass having a lower mass ratio to TiO. Accordingly, the drawn line indicates that the glass according to the invention is reduced in thickness by 100 nm to 100 nm so that, at the same refractive index, the desired density for the respective application is obtained. 2 , Nb 2 O 5 and La 2 O 3 Furthermore, at the same time, the TiO content defined for each refractive index can be modified. 2 Nb 2 O 5 This can affect the transmittance properties of the glass because the TiO 2 Content and Nb 2 O 5As the content increases, the oxygen demand of the melt increases and the glass becomes more redox sensitive, which can lead to a deterioration in transmittance. In summary, the density and transmittance of the glasses according to the invention can be adjusted for a target range of refractive index to obtain an optimized glass for the respective application.

Claims

1. Refractive index n d 1.95–2.05, and variance v d Glass having a concentration of 22 to less than 35, and containing the following components in mass%: Yes 2 4~12 B 2 O 3 4~11 BaO < 10 L 2 O 3 30~<52 Gd 2 O 3 <14 ZrO 2 <5.5 TO 2 10 to 25 Nb 2 O 5 3~16 ZnO ≤ 2.0 This includes, where SiO 2 and B 2 O 3 The glass wherein the total mass percentage of the elements is at least 10% by mass.

2. Y 2 O 3 The glass according to claim 1, wherein the proportion of is 0 to 5% by mass, preferably 0.1 to 2% by mass, and more preferably 0.5 to 1.5% by mass.

3. La 2 O 3 , TiO 2 The glass according to claim 1, wherein the total proportion of BaO is 55 to 70% by mass.

4. The glass according to claim 1, wherein the proportion of BaO is greater than 0 to 9% by mass, preferably 1 to 9% by mass, and particularly preferably 2 to 8.5% by mass.

5. ZrO 2 The glass according to claim 1, wherein the proportion is 0.5 to 5% by mass, more preferably 0.5 to 4.5% by mass, and even more preferably 1.0 to 4.0% by mass.

6. The glass according to claim 1, wherein the proportion of ZnO is 1.5% by mass or less, preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less.

7. SiO 2 B 2 O 3 Mass ratio to proportion (SiO 2 / B 2 O 3 The glass according to claim 1, wherein the ratio is in the range of 0.85 to 2.0, preferably 0.95 to 1.9, and more preferably 1.0 to 1.

8.

8. The glass according to claim 1, wherein the glass has an internal transmittance TI of at least 80% as measured at a wavelength of 460 nm and a sample thickness of 10 mm.

9. Nb 2 O 5 and ZrO 2 The sum of the proportions of TiO 2 The glass according to claim 1, wherein the mass ratio to the proportion is less than 1, preferably less than 0.9, preferably less than 0.8, and preferably less than 0.

7.

10. A glass article comprising the glass described in any one of claims 1 to 9, • Eyeglass glass, especially in the form of wafer stacks. • Wafers, especially wafers having a maximum diameter of 5.0 cm to 40.0 cm, Lenses, especially spherical lenses, prisms or aspherical lenses, and / or Optical waveguides, especially fiber or plate The article in the form of the aforementioned article.

11. Use of the glass according to any one of claims 1 to 9 in AR glasses, wafer-level optical components, optical wafer applications, or conventional optical components, and / or as a wafer, lens, spherical lens, or optical waveguide.

Images