Glass molding mold for optical element molding and method for manufacturing optical element

Abstract

[Subject] Provide a glass molding mold for molding an optical element with low temperature dependence of elasticity and a method for manufacturing an optical element. [Solution] A glass molding mold for molding an optical element. The glass is an aluminosilicate glass, and in the glass composition expressed in mole % of the glass, the total content of SiO2 and Al2O3 is 60% or more, and the molar ratio of the total content of Li2O, Na2O and K2O to the content of MgO (Li2O+Na2O+K2O) / MgO is in the range of 0.000 to 0.400.

Description

Technical Field

[0001] The present invention relates to a glass molding mold for molding an optical element and a method for manufacturing the optical element. Background Art

[0002] As a method for manufacturing optical elements such as lenses, a method of press-molding a molding material using a molding die is widely used. As a molding die that can be used in this manufacturing method, Patent Document 1 discloses a glass molding die.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-127425 Summary of the invention

[0006] Problems to be solved by the invention

[0007] When a molding die is used to perform compression molding on a molding material to mass-produce optical elements, a molding die is usually used to repeatedly perform compression molding on a plurality of molding materials. From the perspective of stably supplying optical elements with desired optical properties to the market, it is preferred that the shape deviation of such mass-produced optical elements is small. In the process of repeatedly conducting in-depth research on this point, the inventors have obtained the following new discovery: as a glass molding die, a glass molding die with low temperature dependence of elasticity is preferred. This is because, when the molding material is compression molded, the glass molding die undergoes a heating process and a cooling process together with the molding material. If the elasticity of the glass molding die in the process changes greatly, the molding surface shape of the glass molding die will change significantly, and the surface shape of the optical element molded by transferring the molding surface will deviate.

[0008] In view of the above circumstances, an object of one embodiment of the present invention is to provide a glass molding mold having a small temperature dependency of elasticity.

[0009] Means for solving problems

[0010] The inventors of the present invention have repeatedly conducted in-depth studies and have made a new discovery as a result: in aluminosilicate glass, by setting the molar ratio of the total content of Li2O, Na2O and K2O to the content of MgO (Li2O+Na2O+K2O) / MgO in the range of 0.000 to 0.400, it is possible to suppress the elasticity of the glass from changing significantly with temperature. Specifically, it is possible to suppress the temperature dependence of the Young's modulus.

[0011] That is, one embodiment of the present invention relates to a glass molding mold for molding an optical element, wherein:

[0012] The above glass is aluminosilicate glass.

[0013] In the glass composition expressed in mol% of the above glass,

[0014] The total content of SiO2 and Al2O3 is more than 60%, and

[0015] The molar ratio of the total content of Li2O, Na2O and K2O to the content of MgO (Li2O+Na2O+K2O) / MgO is in the range of 0.000 to 0.400.

[0016] Another embodiment of the present invention relates to a method for producing an optical element, comprising press-molding a material to be molded using the glass molding die described above.

[0017] Effects of the Invention

[0018] According to one embodiment of the present invention, a glass molding mold can be provided, which is a glass molding mold for molding an optical element and has low temperature dependence of elasticity. In addition, according to one embodiment of the present invention, a method for manufacturing an optical element can be provided, which uses the above-mentioned glass molding mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic cross-sectional view showing an example of an optical element manufacturing apparatus including a glass molding mold.

[0020] Figure 2 This is a schematic cross-sectional view showing an example of an apparatus for manufacturing a glass molding die. DETAILED DESCRIPTION

[0021] [Glass molding mold for optical element molding]

[0022] The glass molding die is described in more detail below. The following description may refer to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

[0023] <Constitution of glass molding mold>

[0024] Figure 1 This is a schematic cross-sectional view of an example of an optical element manufacturing apparatus including a glass molding mold. Figure 1The optical element manufacturing device 10 is a manufacturing device for manufacturing an optical element 20 from a molding material 21 by compression molding, and includes an upper mold 11 and a lower mold 12 as glass molding molds. The upper mold 11 and the lower mold 12 are supported in a guide mold 13 in a relatively movable manner, and the mutual interval can be changed. Both the upper mold 11 and the lower mold 12 can be movable molds, or one can be a movable mold and the other can be a fixed mold that does not move.

[0025] The glass molding mold having the above composition may be the upper mold 11 in one embodiment, and may be the lower mold 12 in another embodiment. In addition, in another embodiment, the upper mold 11 and the lower mold 12 may both be glass molding molds having the above composition. The glass constituting the upper mold 11 and the lower mold 12 may be the same glass in one embodiment, and may be different glasses in another embodiment. In a preferred embodiment, the two molding molds, the upper mold 11 and the lower mold 12, may be glass molding molds having the above composition, and in a more preferred embodiment, the glass constituting the upper mold 11 and the lower mold 12 may be the same glass.

[0026] The upper mold 11 and the lower mold 12 have a molding surface 14 and a molding surface 15 on the sides facing each other. Specifically, the optical element 20 is a biconvex lens with aspheric surfaces on both sides, and the molding surface 14 and the molding surface 15 are concave surfaces (aspheric surfaces) of shapes corresponding to the convex surfaces (aspheric surfaces) of the optical element 20. That is, the shapes of the molding surface 14 and the molding surface 15 are transferred by compression molding to form the convex surface of the optical element 20. However, Figure 1 The embodiments shown are merely examples, and the molding surface of the glass molding die has a convex shape in one embodiment and a concave shape in another embodiment.

[0027] Films 16 and 17 are formed on the molding surfaces 14 and 15, respectively. The films 16 and 17 may be films generally called mold release films, such as carbon films, and can play a role in suppressing the thermal adhesion of the molding material. Figure 1 The coatings 16 and 17 shown are single-layer structures, but coatings of multiple layers having different compositions may be provided. Alternatively, a configuration may be selected in which the coatings 16 and 17 are not provided and the molding surfaces 14 and 15 are exposed.

[0028] A heater (not shown) is provided outside the guide die 13. During molding, the heater can be used to heat the molding material 21 to a molding temperature at which the molding material 21 softens.

[0029] In the present invention and this specification, "glass molding die" refers to a part having a molding surface. Figure 1In the embodiment, the upper mold 11 and the lower mold 12 may be made entirely of glass except for the coatings 16 and 17. Alternatively, only a portion of the upper mold 11 and the lower mold 12 including the molding surface 14 and the molding surface 15 may be made of glass, and a base portion made of other materials such as metal may be joined to the glass portion to form the upper mold 11 and the lower mold 12.

[0030] Hereinafter, the glass constituting the above-mentioned glass forming mold will be described in more detail.

[0031] <Glass Composition>

[0032] In the present invention and this specification, the glass composition is expressed by the cation components of the glass on an oxide basis. Here, the "glass composition on an oxide basis" refers to the glass composition obtained by converting the glass raw materials so that they are completely decomposed during melting and exist in the glass as oxides. In addition, unless otherwise specified, the glass composition is expressed on a molar basis (molar %, molar ratio).

[0033] The various components constituting the glass can be quantitatively determined by a known method, such as inductively coupled plasma emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), etc. The content of each element (mass %) contained in the glass can be divided by the atomic weight to obtain the content of each element expressed in mol %.

[0034] In the present invention and this specification, "the content of a constituent is 0% or is not contained or not introduced" means that the constituent is not substantially contained, but inclusion of the constituent at an unavoidable impurity level is permitted.

[0035] The above-mentioned glass is aluminosilicate glass. In the present invention and this specification, "aluminosilicate glass" refers to a glass containing at least SiO2 and Al2O3 as cationic components of the glass in the glass composition expressed on an oxide basis. In the above-mentioned glass, the total content of SiO2 and Al2O3 (SiO2+Al2O3) is 60.0% or more. It is believed that the total content (SiO2+Al2O3) of 60.0% or more helps to reduce the temperature dependence of elasticity (specifically, the temperature dependence of Young's modulus, the same below). From this aspect, the total content (SiO2+Al2O3) is preferably greater than 65.0%. On the basis of the above aspects, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is preferably greater than 66.0%. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably greater than 68.0%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably greater than 70.0%.

[0036] On the other hand, from the perspective of further reducing the temperature dependence of elasticity, the total content (SiO2+Al2O3) is preferably less than 91.0%. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is normally carried out (for example, Young's modulus), it is preferably less than 90.5%. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably less than 90.5%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 89.5%.

[0037] From the perspective of reducing the temperature dependence of elasticity, the molar ratio of the total content of Li2O, Na2O and K2O to the content of MgO ((Li2O+Na2O+K2O) / MgO) is 0.400 or less, preferably 0.300 or less. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the press molding process is usually performed (e.g., Young's modulus), it is preferably 0.200 or less. Based on these, from the perspective of improving the heat resistance of the glass (e.g., glass transition temperature), it is preferably 0.150 or less. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (e.g., α low described later), it is preferably 0.100 or less. The molar ratio ((Li2O+Na2O+K2O) / MgO) is 0.000 or more, and can be 0.000 or more.

[0038] The molar ratio of the MgO content to the total content of MgO+CaO+SrO+BaO (MgO / (MgO+CaO+SrO+BaO)) can be, for example, 1.000 or less. From the perspective of further reducing the temperature dependence of elasticity, the molar ratio (MgO / (MgO+CaO+SrO+BaO)) is preferably 0.500 or more. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the press molding process is usually performed (e.g., Young's modulus), it is preferably 0.550 or more. Based on these, from the perspective of improving the heat resistance of the glass (e.g., glass transition temperature), it is preferably 0.600 or more. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (e.g., α low described later), it is preferably 0.650 or more.

[0039] The total content of Li2O+Na2O+K2O (Li2O+Na2O+K2O) may be, for example, 0.0% or more or greater than 0.0%. In addition, the total content (Li2O+Na2O+K2O) may be, for example, 4.25% or less. From the perspective of further reducing the temperature dependence of elasticity, the total content (Li2O+Na2O+K2O) is preferably 4.0% or less. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually performed (for example, Young's modulus), it is preferably 3.0% or less. Based on these, from the perspective of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 2.0% or less. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 1.0% or less.

[0040] The total content of Na2O and K2O (Na2O+K2O) may be, for example, 0.0% or more or greater than 0.0%. In addition, the total content (Na2O+K2O) may be, for example, 4.25% or less. In order to further reduce the temperature dependence of elasticity or to prevent the thermal expansion coefficient from being too large, the total content (Na2O+K2O) may be, for example, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, or 0.5% or less.

[0041] The total content of MgO, CaO, SrO and BaO (MgO+CaO+SrO+BaO) may be, for example, 35.0% or less. From the perspective of further reducing the temperature dependence of elasticity, the total content (MgO+CaO+SrO+BaO) is preferably 32.5% or less. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the press molding process is usually performed (e.g., Young's modulus), it is preferably 30.0% or less. Based on these, from the perspective of improving the heat resistance of the glass (e.g., glass transition temperature), it is preferably 27.5% or less. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (e.g., α low described later), it is preferably 25.0% or less.

[0042] In addition, the total content (MgO+CaO+SrO+BaO) may be, for example, 0.0% or more or 1.0% or more. From the perspective of further reducing the temperature dependence of elasticity, the total content (MgO+CaO+SrO+BaO) is preferably 8.0% or more. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the press molding process is usually performed (e.g., Young's modulus), it is preferably 8.5% or more. Based on these, from the perspective of improving the heat resistance of the glass (e.g., glass transition temperature), it is preferably 9.0% or more. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (e.g., α low described later), it is preferably 9.5% or more.

[0043] The total content of MgO and CaO (MgO+CaO) may be, for example, 32.5% or less. From the perspective of further reducing the temperature dependence of elasticity, the total content (MgO+CaO) is preferably 30.0% or less. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually performed (e.g., Young's modulus), it is preferably 27.5% or less. Based on these, from the perspective of improving the heat resistance of the glass (e.g., glass transition temperature), it is preferably 25.0% or less. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (e.g., α low described later), it is preferably 22.5% or less.

[0044] In addition, the total content (MgO + CaO) may be, for example, 0.0% or more or 1.0% or more. From the perspective of further reducing the temperature dependence of elasticity, the total content (MgO + CaO) is preferably 8.0% or more. Based on the above, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually performed (e.g., Young's modulus), it is preferably 8.5% or more. Based on these, from the perspective of improving the heat resistance of the glass (e.g., glass transition temperature), it is preferably 9.0% or more. Based on these, from the perspective of improving the thermal expansion characteristics of the glass (e.g., α low described later), it is preferably 9.5% or more.

[0045] The total content of SiO2, Al2O3 and MgO (SiO2+Al2O3+MgO) can be, for example, 100.0% or less or less than 100.0%. In addition, the total content (SiO2+Al2O3+MgO) can be, for example, 80.0% or more. From the perspective of further reducing the temperature dependence of elasticity, the total content (SiO2+Al2O3+MgO) is preferably 85.0% or more. On the basis of the above, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually performed (for example, Young's modulus), it is preferably 86.0% or more. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 87.0% or more. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 88.0% or more.

[0046] The total content of Li2O, Na2O, K2O, SrO and BaO (Li2O+Na2O+K2O+SrO+BaO) may be, for example, 0.0% or more or greater than 0.0%.

[0047] In addition, the total content (Li2O+Na2O+K2O+SrO+BaO) can be, for example, 4.5% or less. From the perspective of further reducing the temperature dependence of elasticity, it is preferably 3.5% or less. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is preferably 3.0% or less. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, glass transition temperature), it is preferably 2.0% or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 1.0% or less.

[0048] The total content of SiO2, Al2O3, MgO, CaO, ZrO2 and TiO2 (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2) may be, for example, 100.0% or less or less than 100.0%. In addition, the total content (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2) may be, for example, 85.0% or more, preferably 90.0% or more from the perspective of further reducing the temperature dependence of elasticity, and preferably 91.0% or more from the perspective of improving the rigidity of the glass at the temperature at which the press molding process is usually performed (for example, Young's modulus), and preferably 92.0% or more from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), and preferably 93.0% or more from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later).

[0049] The molar ratio of the total content of Li2O, Na2O and K2O to the total content of MgO and CaO ((Li2O+Na2O+K2O) / (MgO+CaO)) can be, for example, 0.000 or more or greater than 0.000. In addition, the molar ratio ((Li2O+Na2O+K2O) / (MgO+CaO)) can be, for example, 2.000 or less. From the perspective of further reducing the temperature dependence of elasticity, it is preferably 0.150 or less. On the basis of the above aspects, from the perspective of improving the rigidity of the glass at the temperature at which the press molding process is usually performed (for example, Young's modulus), it is preferably 0.100 or less. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably 0.050 or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 0.030 or less.

[0050] The molar ratio of the total content of Li2O+Na2O+K2O to the total content of SiO2+Al2O3+MgO ((Li2O+Na2O+K2O) / (SiO2+Al2O3+MgO)) can be, for example, 0.000 or more or greater than 0.000. In addition, the molar ratio ((Li2O+Na2O+K2O) / (SiO2+Al2O3+MgO)) can be, for example, 0.050 or less. From the perspective of further reducing the temperature dependence of elasticity, it is preferably 0.040 or less. On the basis of the above aspects, from the perspective of improving the rigidity of the glass (for example, Young's modulus) at the temperature at which the press molding process is usually performed, it is preferably 0.030 or less. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably 0.020 or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 0.010 or less.

[0051] The molar ratio of the total content of Li2O+Na2O+K2O+SrO+BaO to the total content of SiO2+Al2O3+MgO+CaO+ZrO2+TiO2 ((Li2O+Na2O+K2O+SrO+BaO) / (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2)) can be above 0.000 or greater than 0.000. In addition, the molar ratio ((Li2O+Na2O+K2O+SrO+BaO) / (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2)) can be, for example, less than 0.100. From the perspective of further reducing the temperature dependence of elasticity, it is preferably less than 0.090. On the basis of the above aspects, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is preferably less than 0.080. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably less than 0.060. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 0.050.

[0052] The total content of La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5 and HfO2 (La2O3+Y2O3+Yb2O3+Ta2O5+Nb2O5+HfO2) may be 0.000% or more or greater than 0.000%. In addition, the total content (La2O3+Y2O3+Yb2O3+Ta2O5+Nb2O5+HfO2) may be, for example, 5.0% or less. From the perspective of further reducing the temperature dependence of elasticity or not making the specific modulus too small, it is preferably 4.0% or less, 3.0% or less, 2.0% or less, and 1.0% or less, respectively.

[0053] SiO2 is a skeleton component of glass and is a useful component in reducing the temperature dependence of elasticity. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the SiO2 content is preferably 51.0% or more, from the perspective of further reducing the temperature dependence of elasticity, it is preferably 55.0% or more, based on the above aspects, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually performed (for example, Young's modulus), it is preferably 56.0% or more, based on these aspects, from the perspective of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 57.0% or more, and based on these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 58.0% or more.

[0054] In addition, from the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the SiO2 content is preferably less than 79.0%, from the perspective of further reducing the temperature dependence of elasticity, it is preferably less than 76.0%, and on the basis of the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is normally carried out (for example, Young's modulus), it is preferably less than 75.0%, and on the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, glass transition temperature), it is preferably less than 74.0%, and on the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 73.0%.

[0055] Al2O3 is a skeleton component of glass and is a useful component in reducing the temperature dependence of elasticity. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the Al2O3 content is preferably 8.0% or more, from the perspective of further reducing the temperature dependence of elasticity, it is preferably 10.0% or more, based on the above aspects, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually performed (for example, Young's modulus), it is preferably 11.0% or more, based on these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably 12.0% or more, and based on these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 12.5% ​​or more.

[0056] In addition, from the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the Al2O3 content is preferably less than 24.0%, and from the perspective of further reducing the temperature dependence of elasticity, it is preferably less than 22.0%. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is normally carried out (for example, Young's modulus), it is preferably less than 21.0%. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, the glass transition temperature), it is preferably less than 20.5%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 20.0%.

[0057] B2O3 is a component that can be optionally contained in the glass, for example, in order to adjust the viscosity of the glass. The B2O3 content can be, for example, 0.0% or more or greater than 0.0%, and can be 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more from the perspective of suppressing the generation of bubbles, ribs, and / or undissolved matter in the glass molding mold.

[0058] In addition, from the perspective of further reducing the temperature dependence of elasticity, the B2O3 content is preferably less than 2.0%. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is also preferably less than 2.0%. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is also preferably less than 2.0%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is also preferably less than 2.0%.

[0059] MgO is a component that can contribute to the improvement of the Young's modulus of the glass, the reduction of the specific gravity (and the improvement of the specific modulus by reducing the specific gravity) and / or the reduction of α described later. The MgO content can be 0.0% or more, more than 0.0% or 1.0% or more, preferably 6.0% or more from the aspect of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass forming mold, preferably 8.0% or more from the aspect of further reducing the temperature dependence of elasticity, and based on the above aspects, preferably 8.5% or more from the aspect of improving the rigidity of the glass at the temperature of the usual press molding process (for example, Young's modulus), based on these aspects, preferably 9.0% or more from the aspect of improving the heat resistance of the glass (for example, glass transition temperature), and based on these aspects, preferably 9.5% or more from the aspect of improving the thermal expansion characteristics of the glass (for example, α low described later).

[0060] In addition, the MgO content can be, for example, less than 30.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the MgO content is preferably less than 24.0%. From the perspective of further reducing the temperature dependence of elasticity, the MgO content is preferably less than 22.0%. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass (for example, Young's modulus) at the temperature at which the press molding process is normally carried out, the MgO content is preferably less than 21.0%. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, the glass transition temperature), the MgO content is preferably less than 20.5%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), the MgO content is preferably less than 20.0%.

[0061] The CaO content may be 0.0% or more. CaO is a component that can contribute to the improvement of the Young's modulus and the reduction of the specific gravity of the glass (and the improvement of the specific modulus due to the reduction of the specific gravity), and is preferably used together with MgO.

[0062] The CaO content can be, for example, 15.0% or less. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold and suppressing the decrease in the glass transition temperature, the CaO content is preferably 10.0% or less. From the perspective of further reducing the temperature dependence of elasticity, the CaO content is preferably 8.0% or less. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass (for example, Young's modulus) at the temperature at which the press molding process is normally carried out, the CaO content is preferably 7.0% or less. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, glass transition temperature), the CaO content is preferably 6.0% or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), the CaO content is preferably 5.5% or less.

[0063] The SrO content may be 0.0% or more or more than 0.0%. SrO is a component that can contribute to adjusting the solubility of glass, and is also a component that can contribute to further reducing the temperature dependency of elasticity by replacing with an alkali component.

[0064] The SrO content can be, for example, 12.0% or less. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold and suppressing the reduction of the Young's modulus of the glass, the SrO content is preferably 6.0% or less. From the perspective of further reducing the temperature dependence of the elasticity, the SrO content is preferably 5.0% or less. On the basis of the above aspects, from the perspective of improving the rigidity of the glass (for example, Young's modulus) at the temperature at which the press molding process is usually carried out, the SrO content is preferably 4.0% or less. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, the glass transition temperature), the SrO content is preferably 3.5% or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), the SrO content is preferably 3.0% or less.

[0065] The BaO content may be 0.0% or more or more. BaO is a component that can contribute to adjusting the solubility of glass, and is also a component that can contribute to further reducing the temperature dependency of elasticity by replacing with an alkali component.

[0066] The BaO content can be, for example, less than 12.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold and suppressing the reduction of the Young's modulus of the glass, it is preferably less than 8.0%. From the perspective of further reducing the temperature dependence of elasticity, it is preferably less than 5.0%. On the basis of the above aspects, from the perspective of improving the rigidity of the glass (for example, Young's modulus) at the temperature at which the molding process is normally carried out, it is preferably less than 4.5%. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably less than 4.0%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 3.8%.

[0067] The ZnO content may be 0.0% or more or greater than 0.0%. Suppressing the ZnO content to a certain amount or less can contribute to suppressing a decrease in the glass transition temperature and / or a decrease in the specific modulus.

[0068] The ZnO content can be, for example, 10.0% or less. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold and the above-mentioned aspects, it is preferably 5.0% or less. From the perspective of further reducing the temperature dependence of elasticity, it is preferably 4.0% or less. On the basis of the above-mentioned aspects, from the perspective of increasing the rigidity of the glass (for example, Young's modulus) at the temperature at which the press molding process is normally carried out, it is preferably 3.5% or less. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, the glass transition temperature), it is preferably 3.0% or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 2.5% or less.

[0069] The Li2O content may be 0.0% or more. Reducing the Li2O content to a certain amount or less can help further reduce the temperature dependence of elasticity, suppress the decrease in glass transition temperature, and / or suppress the decrease in Young's modulus.

[0070] The Li2O content can be, for example, 8.0% or less. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold and the above-mentioned aspects, it is preferably 3.0% or less. From the perspective of further reducing the temperature dependence of elasticity, it is preferably 2.0% or less. On the basis of the above-mentioned aspects, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is preferably 1.5% or less. On the basis of these aspects, from the perspective of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 1.0% or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 0.5% or less.

[0071] The Na2O content may be 0.0% or more. Suppressing the Na2O content to a certain amount or less can help further reduce the temperature dependence of elasticity, suppress the decrease in glass transition temperature, and / or suppress the decrease in Young's modulus.

[0072] From the perspective of further reducing the temperature dependence of elasticity, the Na2O content is preferably less than 3.0%. Based on the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is preferably less than 2.0%. Based on these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably less than 1.0%. Based on these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 0.5%.

[0073] The K2O content may be 0.0% or more. Suppressing the K2O content to a certain amount or less can help further reduce the temperature dependence of elasticity, suppress the decrease in glass transition temperature, and / or suppress the decrease in Young's modulus.

[0074] From the perspective of further reducing the temperature dependence of elasticity, the K2O content is preferably 3.0% or less. Based on the above aspects, from the perspective of improving the rigidity of the glass at the temperature at which the molding process is usually carried out (for example, Young's modulus), it is preferably 2.0% or less. Based on these aspects, from the perspective of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably 1.0% or less. Based on these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 0.5% or less.

[0075] ZrO2 is a component that can be optionally contained in the above-mentioned glass, for example, in order to increase the Young's modulus. The ZrO2 content can be, for example, 0.0% or more or greater than 0.0%. The ZrO2 content can be, for example, 10.0% or less. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, it is preferably 4.0% or less. From the perspective of further reducing the temperature dependence of elasticity, it is preferably 2.0% or less. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass at the temperature at which the molding process is usually performed (for example, Young's modulus), it is preferably 2.0% or less. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, the glass transition temperature), it is preferably 1.0% or less. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably 0.5% or less.

[0076] TiO2 is a component that can be optionally contained in the above-mentioned glass in order to increase Young's modulus and / or suppress the generation of bubbles in the glass molding mold. The TiO2 content can be, for example, 0.0% or more or greater than 0.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the TiO2 content can be 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more.

[0077] In addition, the TiO2 content can be, for example, less than 6.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, it is preferably less than 5.0%. From the perspective of further reducing the temperature dependence of elasticity, it is preferably less than 4.0%. On the basis of the above aspects, from the perspective of increasing the rigidity of the glass (for example, Young's modulus) at the temperature at which the molding process is normally carried out, it is preferably less than 3.0%. On the basis of these aspects, from the perspective of increasing the heat resistance of the glass (for example, the glass transition temperature), it is preferably less than 2.0%. On the basis of these aspects, from the perspective of improving the thermal expansion characteristics of the glass (for example, α low described later), it is preferably less than 1.0%.

[0078] From the perspective of reducing the temperature dependence of elasticity, the La2O3 content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. The La2O3 content may be 0.0%, 0.0% or more, or greater than 0.0%.

[0079] From the perspective of reducing the temperature dependence of elasticity, the Y2O3 content is preferably 4.0% or less, more preferably 3.0% or less, and preferably 2.0% or less. The Y2O3 content may also be 1.0% or less or 0.5% or less, or may be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0080] From the perspective of reducing the temperature dependence of elasticity, the Yb2O3 content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. The Yb2O3 content may also be 1.0% or less or 0.5% or more, or 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0081] From the perspective of reducing the temperature dependence of elasticity, the Ta2O5 content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. The Ta2O5 content may also be 1.0% or less or 0.5% or more, or 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0082] From the perspective of reducing the temperature dependence of elasticity, the Nb2O5 content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. The Nb2O5 content may also be 1.0% or less or 0.5% or less, or may be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0083] From the perspective of reducing the temperature dependence of elasticity, the HfO2 content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. The HfO2 content may also be 1.0% or less or 0.5% or more, or 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0084] SnO2 is a component that can be optionally contained in the above-mentioned glass in order to increase Young's modulus and / or suppress the generation of bubbles in the glass molding mold. The SnO2 content can be, for example, 0.0% or more or greater than 0.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the SnO2 content can be 0.05% or more, 0.3% or more, or 0.5% or more.

[0085] In addition, from the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the SnO2 content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, and preferably 0.5% or less. The SnO2 content may also be 0.2% or less or 0.1%, or 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0086] CeO2 is a component that can be optionally contained in the above-mentioned glass in order to increase Young's modulus and / or suppress the generation of bubbles in the glass molding mold. The CeO2 content can be, for example, 0.0% or more or greater than 0.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the CeO2 content can be 0.05% or more, 0.3% or more, or 0.5% or more.

[0087] In addition, from the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the CeO2 content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, and preferably 0.5% or less. The CeO2 content may also be 0.2% or less or 0.1%, or 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0088] Sb2O3 is a component that can be optionally contained in the above-mentioned glass in order to increase Young's modulus and / or suppress the generation of bubbles in the glass molding mold. The Sb2O3 content can be, for example, 0.0% or more or greater than 0.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the Sb2O3 content can be 0.05% or more, 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more.

[0089] In addition, from the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the Sb2O3 content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, and preferably 0.5% or less.

[0090] Fe2O3 is a component that can be optionally contained in the glass, for example, in order to increase Young's modulus and / or suppress the generation of bubbles in the glass molding mold. The Fe2O3 content can be, for example, 0.0% or more or greater than 0.0%. From the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the Fe2O3 content can be 0.05% or more, 0.3% or more, or 0.5% or more.

[0091] In addition, from the perspective of suppressing the generation of bubbles, ribs and / or undissolved matter in the glass molding mold, the Fe2O3 content is preferably 2.0% or less, preferably 1.0% or less, preferably 0.5% or less, preferably 0.2% or less, and preferably 0.01% or less.

[0092] <Glass Properties>

[0093] In one embodiment, the glass constituting the glass molding die may have one or more of the glass properties described below.

[0094] (Glass transition temperature Tg, yield point temperature Ts)

[0095] In the present invention and this specification, the glass transition temperature Tg and the deformation point temperature Ts of the glass constituting the above-mentioned glass molding die are values ​​obtained by the following method.

[0096] A glass sample is cut out from a glass molding mold, or a glass sample made of the same material as the glass molding mold is prepared. For each glass sample, the thermal expansion characteristics are measured by the method according to JOGIS08-2003. Specifically, the temperature of 10°C is obtained by rounding off the first digit of the Tg (unit: °C) of the glass, and the temperature is set as the annealing temperature. The glass sample is placed in an annealing furnace that can be heated to the temperature, and the temperature is raised from room temperature (about 25°C) to the above-mentioned set temperature in 1 to 2 hours. After keeping for 2 hours, the temperature is lowered at a cooling rate of -30°C / hour for 4 hours, and then naturally cooled at room temperature (about 25°C) in the furnace. The naturally cooled glass sample is processed into a cylindrical glass sample with a diameter of 4.0mm to 5.0mm and a length of 10mm to 20mm. A load of 98mN is applied to the glass sample, and it is heated at a heating rate of 4°C / minute in this state. The elongation (unit: mm) relative to the temperature is measured every 1 second, and the resulting curve (the so-called thermal expansion curve) is prepared. The temperature corresponding to the intersection of the extended lines of the straight line parts of the low temperature area and the high temperature area in the above curve is taken as the glass transition temperature Tg, and the temperature at which the expansion apparently stops in the above curve, that is, the inflection point temperature where the elongation changes from increasing to decreasing as the temperature rises, is taken as the yield point temperature Ts.

[0097] In order to make the glass molding mold suitable for compression molding at a higher temperature, the glass transition temperature Tg of the glass is preferably 755°C or higher, more preferably 760°C or higher, further preferably 765°C or higher, and even more preferably 770°C or higher. In addition, the glass transition temperature Tg of the glass may be, for example, 860°C or lower, 855°C or lower, 850°C or lower, 845°C or lower, or 840°C or lower.

[0098] In addition, in order to make the glass forming mold suitable for press molding at a higher temperature, the yield point temperature Ts of the glass is preferably 830°C or higher, more preferably 835°C or higher, further preferably 840°C or higher, and even more preferably 845°C or higher. In addition, the yield point temperature Ts of the glass may be, for example, 940°C or lower, 935°C or lower, 930°C or lower, 925°C or lower, or 920°C or lower.

[0099] (Average linear expansion coefficient α)

[0100] For example Figure 1As shown, a glass molding mold and a guide mold can be combined to form an optical element manufacturing device. From the perspective of controlling the stress on the glass molding mold in the optical element manufacturing device when combined with the guide mold and other components, it is preferred to adjust the thermal expansion characteristics of the glass constituting the glass molding mold. In one embodiment, the thermal expansion characteristics of the glass constituting the glass molding mold are preferably 23.5×10 -7 / °C or more, more preferably 24.0×10 -7 / °C or more, more preferably 24.5×10 -7 / °C or more, more preferably 25.0×10 -7 / °C or more. In addition, the average linear expansion coefficient α of the glass is preferably 48.0×10 -7 / °C or less, more preferably 47.0×10 -7 / °C or less, more preferably 46.0×10 -7 / ℃ or less, more preferably 45.0×10 -7 / °C or less, and more preferably 44.0×10 -7 / ℃ below.

[0101] The above average linear expansion coefficient α is calculated by the formula: α = d / (L×T). d is the change in sample length in the temperature range of 100°C to 300°C (mm), L is the initial length of the sample (mm), and T is the temperature difference (K) (300°C-100°C=200°C). As a measuring device for the linear expansion coefficient, a thermomechanical analyzer (TMA; ThermomechanicalAnalysis) or a dilatometer can be used.

[0102] The average linear expansion coefficient α can be obtained, for example, by the following method.

[0103] For a glass sample cut out from a glass molding mold or a glass sample made of the same material as the glass molding mold, a thermomechanical analysis device (TMA) is used to round off the Tg (unit: °C) of the glass to a temperature of 10°C on the scale, and the temperature is set as the annealing temperature. The glass sample is placed in an annealing furnace that can be heated to the temperature, and the temperature is raised from room temperature (about 25°C) to the above-set temperature in 1 to 2 hours, and then maintained for 2 hours, and then slowly cooled at -30°C / hour for 4 hours, and then naturally cooled to room temperature (about 25°C) in the furnace, and the naturally cooled glass sample is processed into a cylindrical glass sample with a diameter of 4.0mm to 5.0mm and a length of 10mm to 20mm. A load of 98mN is applied to the glass sample, and in this state, the temperature is heated at a heating rate of 4°C / minute, and the elongation (unit: mm) relative to the temperature is measured every 1 second. From the obtained curve (the so-called thermal expansion curve), the average linear expansion coefficient α can be obtained.

[0104] In one embodiment, the components of the optical element manufacturing apparatus such as the guide die may be made of silicon carbide (SiC). The average linear expansion coefficient α of SiC is 37×10 -7 / ℃. The α of the glass constituting the above-mentioned glass molding mold is "A×10 -7 / °C", from the aspect of suppressing the falling of the optical element during the manufacture of the optical element, X calculated by the formula: X=A-37 is preferably a negative value. From this aspect, X of the above-mentioned glass calculated by the above formula is preferably greater than -13.5, more preferably greater than -13.0, further preferably greater than -12.5, and even more preferably greater than -12.0. In addition, the above-mentioned X can be, for example, less than 11.0, less than 10.0, less than 9.0, less than 8.0 or less than 7.0, and from the above aspect, it is preferably less than 0.0.

[0105] In addition, from the perspective of suppressing the stress on the glass molding mold from the SiC component in the optical element manufacturing apparatus, the absolute value of X |X| is preferably 13.0 or less, more preferably 12.5 or less, further preferably 12.0 or less, and even more preferably 11.5 or less. In addition, the absolute value |X| is preferably 0.0 or more, and more preferably greater than 0.0.

[0106] (proportion)

[0107] From the aspect of the adjustment of the specific modulus described later, it is preferred that the specific gravity of the above-mentioned glass is small. The specific gravity of the above-mentioned glass is preferably below 2.98, more preferably below 2.93, further preferably below 2.88, and even more preferably below 2.83. In addition, the specific gravity of the above-mentioned glass can be, for example, above 2.35, above 2.37, above 2.40, or above 2.43, or can be lower than the value exemplified here. The specific gravity of the above-mentioned glass can be obtained by the Archimedean method for a measuring glass sample cut out from a glass molding mold or for a measuring glass sample composed of the same material as the glass molding mold.

[0108] (Young's modulus)

[0109] From the perspective of suppressing the deformation of the glass molding mold, it is preferred that the glass constituting the glass molding mold has a high Young's modulus. From this perspective, the Young's modulus of the glass is preferably 87 GPa or more, more preferably 88 GPa or more, further preferably 89 GPa or more, and even more preferably 90 GPa or more. In addition, the Young's modulus of the glass may be, for example, 120 GPa or less, 110 GPa or less, 101 GPa or less, 100 GPa or less, 99 GPa or less, 98 GPa or less, or 97 GPa or less, or may exceed the values ​​exemplified herein. The Young's modulus of the glass may be obtained by the ultrasonic pulse method described in JIS R1602:1995 at a measuring temperature of 25°C±5°C for a measuring glass sample cut out from the glass molding mold or for a measuring glass sample made of the same material as the glass molding mold. The size of the measuring glass sample may be appropriately set to a size greater than the minimum size described in JIS R1602:1995.

[0110] Regarding the glass constituting the glass molding mold, it is preferred that the rigidity of the glass at the temperature at which the molding process is usually performed is high. From this aspect, the Young's modulus of the above-mentioned glass at a measurement temperature of 590°C is preferably 80 GPa or more, more preferably 85 GPa or more, further preferably 88 GPa or more, more preferably 90 GPa or more, further preferably 91 GPa or more, and further more preferably 92 GPa or more. In addition, the Young's modulus of the above-mentioned glass at a measurement temperature of 590°C can be, for example, 118 GPa or less, 107 GPa or less, 102 GPa or less, 100 GPa or less, 98 GPa or less, 97 GPa or less, or 96 GPa or less, or it can also exceed the values ​​exemplified here.

[0111] In addition, from the above aspect, the Young's modulus of the glass at a measurement temperature of 650°C is preferably 80 GPa or more, more preferably 84 GPa or more, further preferably 87 GPa or more, further preferably 89 GPa or more, further preferably 90 GPa or more, and further more preferably 91 GPa or more. In addition, the Young's modulus of the glass at a measurement temperature of 650°C may be, for example, 117 GPa or less, 106 GPa or less, 101 GPa or less, 99 GPa or less, 97 GPa or less, 96 GPa or less, or 95 GPa or less, or may exceed the values ​​exemplified here.

[0112] The Young's modulus at the measurement temperature of 590°C or 650°C can be determined by the above-mentioned method for measuring the Young's modulus, except that the measurement temperature is 590°C or 650°C.

[0113] (Specific modulus)

[0114] The specific modulus is obtained by dividing the Young's modulus of the glass by its density. Here, density can be considered as adding g / cm to the specific gravity of the glass. 3 The value obtained by this unit. The molding mold composed of glass with higher specific modulus can be said to be a molding mold that is lighter but not easily deformed. From this aspect, the specific modulus of the above-mentioned glass is preferably 31.0MNm / kg or more, more preferably 32.0MNm / kg or more, further preferably 33.0MNm / kg or more, and more preferably 33.5MNm / kg or more. In addition, the specific modulus of the above-mentioned glass can be, for example, less than 41.0MNm / kg, less than 40.5MNm / kg, less than 40.0MNm / kg, less than 39.5MNm / kg or less than 39.0MNm / kg, and can also exceed the values ​​exemplified here.

[0115] (Modulus of rigidity)

[0116] The rigidity modulus of glass indicates the degree of resistance to shear deformation. From the aspect of suppressing the deformation of the glass forming mold, the rigidity modulus of the glass constituting the glass forming mold is preferably high. From this aspect, the rigidity modulus of the glass can be 33.0 GPa or more, preferably 34.0 GPa or more, 35.0 GPa or more, and 36.0 GPa or more. The rigidity modulus of the glass can be, for example, 42.0 GPa or less, 41.5 GPa or less, 41.0 GPa or less, 40.5 GPa or less, or 40.0 GPa or less.

[0117] The rigidity modulus of the glass can be determined by an ultrasonic pulse method described in JIS R1602: 1995 at a measurement temperature of 25°C ± 5°C for a glass sample cut out from a glass molding mold or a glass sample made of the same material as the glass molding mold. The size of the glass sample can be appropriately set to a size greater than the minimum size described in JIS R1602: 1995.

[0118] (Poisson's ratio)

[0119] The Poisson's ratio of the glass is a unitless parameter obtained by the ratio of the Young's modulus to the rigidity modulus. The Poisson's ratio of the glass may be, for example, 0.190 or more, preferably 0.195 or more, 0.200 or more, 0.205 or more, and 0.210 or more. In addition, the Poisson's ratio of the glass may be, for example, 0.333 or less, preferably 0.300 or less, 0.290 or less, 0.280 or less, 0.270 or less, and 0.260 or less.

[0120] The Poisson's ratio of the glass can be determined by an ultrasonic pulse method described in JIS R1602: 1995 at a measurement temperature of 25°C ± 5°C for a glass sample cut out from a glass molding mold or a glass sample made of the same material as the glass molding mold. The size of the glass sample can be appropriately set to a size greater than the minimum size described in JIS R1602: 1995.

[0121] (Liquid phase temperature LT)

[0122] As an index of the fusibility of glass, the liquidus temperature LT can be cited. From the perspective of improving the fusibility of glass, the liquidus temperature LT of the glass constituting the glass forming mold is preferably 1440°C or less, more preferably 1420°C or less, further preferably 1400°C or less, further preferably 1380°C or less, and further preferably 1360°C or less. In addition, the liquidus temperature LT of the glass can be, for example, 1150°C or more, 1170°C or more, 1200°C or more, or 1230°C or more, and can also be lower than the values ​​exemplified here.

[0123] The "liquidus temperature" in the present invention and this specification is obtained by the following method for a glass sample for measurement cut out from a glass molding die or for a glass sample for measurement made of the same material as the glass molding die.

[0124] About 20cc of glass (for example, 50g for glass with a specific gravity of 2.5g / cc) is placed in a platinum crucible, heated in a furnace at an atmosphere temperature of 1400°C to 1600°C for 15 to 30 minutes to become molten, and then cooled to a temperature below the glass transition temperature Tg. The cooled glass is moved to a furnace at an atmosphere temperature of T and kept in the furnace for 16 hours, and then observed under an optical microscope (magnification 100 times) to determine whether crystals are precipitated.

[0125] The presence or absence of crystal precipitation was determined at different T (10°C scale) by the above method. The lowest temperature T at which crystal precipitation was not confirmed was defined as the liquidus temperature.

[0126] <Method for manufacturing glass molding mold>

[0127] The glass molding die can be manufactured by press-molding a glass blank for the glass molding die using a master mold to form a glass molding die having a molding surface with a concave shape or a convex shape.

[0128] Figure 2 It is a schematic cross-sectional view of an example of a manufacturing apparatus for a glass molding die (hereinafter, also referred to as a "molding die manufacturing apparatus"). Figure 2 The molding die manufacturing device includes an upper mold (mother mold) 31 having a molding surface 34 with a convex shape, a lower mold 32, and a guide mold 33. The glass blank 41 is squeezed between the upper mold 31 and the lower mold 32, and the surface shape of the molding surface 34 of the upper mold is transferred to the glass blank 41, thereby obtaining a glass molding mold having a molding surface with a concave shape. The surface shape of the lower mold 32 can be any one of a flat shape, a convex shape, and a concave shape, without particular limitation. In addition, Figure 2 In the molding die manufacturing device, the mother mold for transferring the surface shape to the glass blank to form the molding surface of the glass molding die is the upper mold, but the mother mold can also be configured as the lower mold.

[0129] The upper mold 31 and the lower mold 32 are supported in a guide mold (also commonly referred to as a "sleeve") 33 in a relatively movable manner, and the distance between them can be changed. The upper mold 31 and the lower mold 32 can both be movable molds, or one can be a movable mold and the other can be a fixed mold.

[0130] A heater (not shown) is provided on the outside of the guide mold 33. During molding, the heater can be used to heat the glass blank 41 to a molding temperature Ta at which the glass blank 41 softens. Ta can be set according to the type of glass blank, and can be, for example, in the range of 700°C to 1000°C, preferably in the range of 750°C to 950°C. In one embodiment, Ta can be set to Ts ± 50°C. Figure 2In the molding die manufacturing device, the upper die, the lower die and the guide die are also heated together with the glass blank by the heater provided on the outer side of the guide die 33.

[0131] The glass blank heated to temperature Ta is in contact with the surface of the master mold ( Figure 2 The glass blank 41 is pressed while being in contact with the molding surface 34 of the upper mold 31. The glass blank 41 can be pressed by applying a pressing load to the glass blank 41 by the upper mold 31 and / or the lower mold 32.

[0132] Thereafter, the glass blank 41 is cooled while in contact with the surface of the master mold. The cooling rate C in the cooling step may be -0.1°C / min or more, -0.3°C / min or more, -0.5°C / min or more, -1.0°C / min or more, -3.0°C / min or more, -5.0°C / min or more, -10.0°C / min or more, or -15.0°C / min or more, in terms of the average cooling rate from Ta to Tb described later, from the perspective of improving the productivity of the glass molding mold and / or suppressing thermal degradation of the master mold. In addition, it can be below -100.0°C / minute, below -50.0°C / minute, below -30.0°C / minute, below -25.0°C / minute, below -20.0°C / minute, below -18.0°C / minute, below -16.0°C / minute, below -14.0°C / minute, below -12.0°C / minute, below -10.0°C / minute, below -5.0°C / minute, below -3.0°C / minute or below -1.0°C / minute.

[0133] In one embodiment, from the perspective of improving productivity, the mold load and / or cooling rate may be switched at a temperature Tm that is higher than Tb and lower than Ta. The cooling rate C at this time may be obtained from the cooling rate Ca (unit: °C / minute) from Ta to Tm and the cooling rate Cb (unit: °C / minute) from Tm to Tb as C (unit: °C / minute) = (Ta-Tb) / {(Ta-Tm) / Ca+(Tm-Tb) / Cb}.

[0134] After the above cooling, the contact state with the master mold surface is released. In this way, the glass blank 41 is molded and can obtain a glass blank having a master mold surface ( Figure 2A glass molding mold having a concave molding surface formed by transferring the surface shape of the molding surface 34 of the upper mold 31. The release of the above-mentioned abutment state can be carried out at a temperature Tb at which the solidification of the glass is fully carried out. Tb can be, for example, a temperature near or below Tg. Tb is preferably sufficiently lower than the strain point of the glass. From this aspect, it can be, for example, below Tg-150°C, preferably below Tg-160°C, more preferably below Tg-180°C, and further preferably below Tg-200°C. From the aspect of making it easy to make the temperature of the glass molding mold and / or the master mold follow the cooling rate, Tb can be, for example, above 20°C, above 50°C, above 70°C, above 100°C, above 150°C, above 200°C, above 250°C, above 300°C, above 350°C or above 400°C. In addition, Tb is preferably sufficiently lower than Tg of the glass molding mold, and from this perspective, it may be, for example, 900° C. or less, 800° C. or less, 700° C. or less, 600° C. or less, 550° C. or less, 500° C. or less, 400° C. or less, 350° C. or less, or 300° C. or less. During the cooling from Ta to Tb, the upper mold 31 and / or the lower mold 32 may continue to apply a pressing load to the glass blank 41 as appropriate, or the load may be only the weight of the mold itself.

[0135] use Figure 2 By using a molding mold forming device, a glass molding mold having a molding surface with a concave shape can be obtained. On the other hand, if the surface shape of the molding surface of the mother mold is a concave shape, by transferring the concave shape to the glass blank, a glass molding mold having a molding surface with a convex shape can be obtained. The glass molding mold taken out from the molding mold forming device can be subjected to any one or more of the known post-processes such as annealing and film formation.

[0136] The material of the master mold is not particularly limited. From the perspective of heat resistance, durability, etc., a master mold made of silicon carbide (SiC) or glass is preferred. The master mold can be produced by a known method.

[0137] [Method for manufacturing optical element]

[0138] One embodiment of the present invention relates to a method for producing an optical element, comprising press-molding a material to be molded using the above-mentioned glass molding die.

[0139] Regarding the method for manufacturing the optical element, in addition to using the glass molding mold described above, known techniques related to the manufacture of optical elements using press molding can be applied. An example of an optical element manufacturing apparatus that can be used for press molding is the one described above. Figure 1 Optical element manufacturing device.

[0140] Examples of the optical element include various lenses such as spherical lenses, aspherical lenses, and micro lenses, and prisms. In addition, the molding material may be a glass blank, and the optical element may be a glass optical element.

[0141] For example, the glass block processed for press molding (hereinafter referred to as "press molding glass blank") can be press molded using the above-mentioned glass molding mold. Examples of press molding glass blanks include preforms for precision press molding, glass blanks for obtaining optical element blanks by press molding (glass droplets for press molding), and other glass blocks having a mass equivalent to that of press molded products. The press molding glass blank is made by a process of processing a glass molded body. The glass molded body can be made by heating and melting glass raw materials and molding the obtained molten glass. As a processing method for the glass molded body, cutting, grinding, and polishing can be exemplified. In addition, the optical element blank is a glass molded body having a shape similar to the shape of the optical element to be manufactured. The optical element blank can be made by a method such as molding glass into a shape obtained by superimposing the processing amount removed by processing on the shape of the optical element to be manufactured. For example, an optical element blank can be produced by heating and softening a press-molding glass blank and performing press molding (reheat press molding), or by supplying a molten glass block to a press molding die using a known method and performing press molding (direct press molding).

[0142] For example, regarding the shape accuracy of the molding surface of the molding die for precision press molding, it is desired that the shape accuracy is several times that required by the optical element. According to the manufacturing method of the glass molding die described above, the surface shape of the master mold can be transferred with high precision to manufacture a glass molding die. The glass molding die thus obtained is suitable as a molding die for precision press molding. However, since the shape accuracy of the molding surface is excellent, it is preferred in various press moldings. Therefore, the glass molding die manufactured by the above-mentioned manufacturing method is not limited to a molding die for precision press molding, and is suitable as a molding die for various press moldings.

[0143] Hereinafter, a specific example of a method for obtaining a glass optical element by press molding will be described.

[0144] A carbon film is coated on the molding surface of the glass molding mold as a mold release film and is arranged in an optical element manufacturing device. After the glass blank for press molding (glass blank to be molded) is supplied to the optical element manufacturing device, it is heated until the viscosity of the glass blank to be molded reaches 10 8 dPa·s~10 12dPa·s equivalent viscosity is softened by pressing it with a molding die, thereby transferring the molding surface of the glass molding die to the molded glass blank. The set temperature of the device at this time is called the molding temperature. It should be noted that in order to prevent oxidation of the molding surface, the atmosphere during molding is preferably set to be non-oxidizing. Afterwards, an appropriate load application program (for example, -50°C / minute, etc.) can be applied to the glass molding die and the molded glass blank, and the molding surface and the molded glass element are maintained in close contact, while cooling to near the glass transition temperature of the glass constituting the molded glass blank, and then the optical element manufacturing device is opened (decomposed) to take out the molded body (optical element).

[0145] Example

[0146] Hereinafter, the present invention will be described in further detail by way of examples, but the present invention is not limited to the embodiments shown in the examples.

[0147] [Examples 1 to 20, Comparative Example 1]

[0148] <Glass blank for glass molding mold>

[0149] Glass materials having the glass compositions shown in Table 1 were prepared by the following method.

[0150] Various oxides, borates, carbonates, and sulfates are used as raw materials for introducing each component to achieve the glass composition shown in Table 1. The raw materials are weighed and fully mixed to prepare the blended raw materials. At this time, a total of 200 g of raw materials in terms of oxide conversion are used. The crucible containing the blended raw materials is placed in a glass melting furnace, and the glass is melted, clarified, and homogenized at 1600°C for 3 hours. The molten glass is poured from the crucible into a preheated mold for molding. Next, the molded glass is taken out of the mold, placed in an annealing furnace with the furnace temperature set at 750°C, and annealed at an annealing cooling rate of -30°C / hour to obtain a glass blank.

[0151] [Table 1-1]

[0152] Table 1

[0153]

[0154] [Table 1-2]

[0155] Table 1 (continued)

[0156]

[0157] <Master mold>

[0158] As a master mold, a SiC master mold is prepared.

[0159] <Preparation of glass molding mold by press molding>

[0160] For each glass blank, use Figure 2 The molding die manufacturing device of the structure shown in the figure performs press molding by the method described above. The temperature Ta is set to a range of 780°C to 900°C, a load is applied to the glass blank while the glass blank is in contact with the surface of the master mold, the temperature Tb is set to a range of 450°C to 650°C, and the cooling rate C (average cooling rate from temperature Ta to Tb) is set to a range of -5.0°C / min to -30.0°C / min, and then the glass blank is cooled naturally to room temperature in the molding die molding device, the contact state with the master mold is released, and the glass molding die with the molding surface formed by transferring the surface shape of the master mold is taken out from the molding die manufacturing device.

[0161] In this way, a glass molding mold having a concave molding surface is produced.

[0162] [Evaluation of glass molding molds]

[0163] <Glass Properties>

[0164] For each glass molding mold of Examples 1 to 20 and Comparative Example 1, various glass properties shown in Table 3 were obtained by the above-described methods and are shown in Table 2. The Young's modulus shown in Table 2 is the Young's modulus at a measurement temperature of 25°C ± 5°C.

[0165] [Table 2]

[0166] Table 2

[0167]

[0168] <Evaluation of Temperature Dependence of Elasticity (Young's Modulus)>

[0169] For each glass molding mold of Examples 1 to 20, the Young's modulus at each measurement temperature was measured at a measurement temperature of 590° C., 650° C., 700° C., and 750° C. by the method exemplified above.

[0170] The glass molding die of Comparative Example 1 was measured at measurement temperatures of 590° C. and 650° C., and the Young's modulus at each measurement temperature was measured by the method exemplified above.

[0171] In Table 3, E(590), E(650), E(700), and E(750) respectively represent Young's modulus at the measurement temperature of the values ​​in parentheses. The unit is "GPa".

[0172] From the measurement results, an approximate straight line was prepared by the least square method with Young's modulus as the vertical axis and the measurement temperature as the horizontal axis, and the slope of the approximate straight line was shown as "Slope of Young's modulus" in Table 3. The unit of the slope of Young's modulus is "GPa / °C".

[0173] The smaller the absolute value of the slope of the Young's modulus thus obtained, the smaller the temperature dependence of the Young's modulus of the glass molding mold can be determined. From the results shown in Table 3, it can be confirmed that the temperature dependence of the Young's modulus of the glass molding molds of Examples 1 to 20 is smaller than that of the glass molding mold of Comparative Example 1. In one embodiment, the slope of the Young's modulus calculated as above from the Young's modulus at the four measurement temperatures of 590°C, 650°C, 700°C and 750°C is preferably -0.0100 GPa / °C or more, more preferably -0.0090 GPa / °C or more, further preferably -0.0080 GPa / °C or more, more preferably -0.0070 GPa / °C or more, further preferably -0.0060 GPa / °C or more, further more preferably -0.0050 GPa / °C or more, further preferably -0.0045 GPa / °C or more, and further preferably -0.0040 GPa / °C or more. The slope of the Young's modulus may be, for example, -0.0010 GPa / °C or less or -0.0020 GPa / °C or less, or may exceed the values ​​exemplified here.

[0174] [Table 3]

[0175] Table 3

[0176]

[0177] [Manufacturing and evaluation of optical components]

[0178] It is believed that when mass-producing optical elements by compression molding, the less the shape change of the molding surface of the glass molding mold is, the more the shape deviation of the optical element can be further suppressed. The degree of change in the shape of the molding surface of the glass molding mold when mass-producing optical elements by compression molding can be evaluated by the following method.

[0179] The glass molding mold is exposed to the molding temperature environment in one lens molding cycle, and after being heated, it is cooled to near the glass transition temperature. It is believed that the shape change of the molding surface of the glass molding mold mainly occurs at the high molding temperature in one lens molding cycle, and the change increases with the increase in the number of moldings. The number of Newton rings is calculated from the shape of the glass molding mold used in lens molding for a certain number of times (number of injections) X or more (for example, more than 50 injections) at a certain molding temperature and the shape before use.

[0180] The number of Newton's rings is calculated by the following method.

[0181] At room temperature (about 25°C), the shape of the molding surface of the glass molding mold is measured using a shape measuring device. As shape measuring equipment, interferometers, three-dimensional measuring machines (such as UA3P manufactured by Panasonic Production Engineering) and the like can be cited. UA3P manufactured by Panasonic Production Engineering is used here. The number of Newton's rings when the measurement wavelength is 546.1nm is calculated from the value of the curvature radius R of the molding surface measured by shape measurement (for non-spherical molding surfaces, it is the paraxial R).

[0182] The difference D between the number of Newton rings before and after use (after use - before use) is divided by the number of injections X, and the obtained value D / X is taken as the Newton ring change ΔN per injection, and it is multiplied by 100 times to obtain the Newton ring change 100D / X per 100 injections. The lower limit of the number of molding times X used to calculate ΔN is set to 50 or more in consideration of the measurement error of ΔN. Regarding the upper limit of X, if X is increased to the point where the glass molding mold no longer changes in shape, the apparent ΔN decreases and may be unsuitable for evaluation. Therefore, the upper limit of X is preferably 100 or less, more preferably 80 or less, and further preferably 60 or less.

[0183] For example, regarding the Newton ring change ΔN per shot at 590°C, the number of Newton rings calculated by the above-described method can be calculated from the shape of the glass molding mold used in lens molding for a certain number of times X (50≤X≤100) at a molding temperature of 590°C and the shape before use, and the difference D (after use - before use) between the number of Newton rings before and after lens molding is divided by the number of shots X, and the resulting value D / X is obtained as "the Newton ring change ΔN per shot at 590°C". The smaller the value thus obtained, the less the shape change of the molding surface of the glass molding mold can be evaluated when mass-producing optical elements by press molding.

[0184] For Examples 7, 11, 12 and Comparative Example 1, the above-mentioned glass molding molds with concave shapes were used as upper and lower molds, respectively, and the above-mentioned specific example method was used to prepare the glass molding molds. Figure 1In the optical element manufacturing apparatus of the structure shown, the precision press molding of the glass blank to be molded is repeatedly performed at a molding temperature of 590°C and an injection number of X (50≤X≤60), and a glass optical element (double convex lens) is manufactured. Then, 100D / X is calculated by multiplying ΔN=D / X obtained by the above method by 100 times, and is shown in Table 4 as "the value obtained by multiplying the Newton ring change ΔN per injection at 590°C by 100 times". The "value obtained by multiplying the Newton ring change ΔN per injection at 590°C by 100 times" can be 0.00 or more or more than 0.00, and 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, and 0.30 or less. Regarding Comparative Example 1, the shape of the molding surface of the molding die changed greatly and press molding up to the shot number X could not be performed, so it is indicated as “press molding not possible” in Table 4.

[0185] [Table 4]

[0186] Table 4

[0187]

[0188] As shown in Table 3, the temperature dependence of the Young's modulus of the glass molding mold of the embodiment composed of the glass having the composition described above is small. The results shown in Table 4 show that when the glass molding mold having such a small temperature dependence of the Young's modulus is used to mass-produce optical elements by press molding, the shape of the molding surface of the glass molding mold changes little.

[0189] Finally, the above methods are summarized.

[0190] According to one embodiment, a glass molding mold is provided, which is a glass molding mold for molding optical elements, wherein the glass is an aluminosilicate glass, and in the glass composition expressed in mole % of the glass, the total content of SiO2 and Al2O3 is greater than 60%, and the molar ratio of the total content of Li2O, Na2O and K2O to the MgO content (Li2O+Na2O+K2O) / MgO is in the range of 0.000 to 0.400.

[0191] The glass molding mold may be a glass molding mold for an optical element, and may have a low temperature dependency of elasticity.

[0192] In one embodiment, in the glass composition expressed in mol % of the glass, the molar ratio of MgO to the total content of MgO, CaO, SrO, and BaO, MgO / (MgO+CaO+SrO+BaO), may be 0.500 or more.

[0193] In one embodiment, in the glass composition expressed in mol % of the above-mentioned glass, the molar ratio of the total content of Li2O, Na2O, K2O, SrO and BaO to the total content of SiO2, Al2O3, MgO, CaO, ZrO2 and TiO2 ((Li2O+Na2O+K2O+SrO+BaO) / (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2)) can be in the range of 0.000 to 0.100.

[0194] In one embodiment, in the glass composition expressed in mol% of the above-mentioned glass, the MgO content can be 1.0% to 30.0%, the CaO content can be 0.0 to 15.0%, the SrO content can be 0.0 to 12.0%, the BaO content can be 0.0 to 12.0%, the ZnO content can be 0.0 to 10.0%, the Li2O content can be 0.0 to 8.0%, the total content of Na2O and K2O can be 0.0 to 4.25%, the ZrO2 content can be 0.0 to 10.0%, the TiO2 content can be 0.0 to 6.0%, and the total content of La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5 and HfO2 can be 0.0 to 4.0%.

[0195] In one embodiment, the glass may have a Young's modulus of 80 GPa or more at a measurement temperature of 590° C.

[0196] In one embodiment, the glass may have a Young's modulus of 80 GPa or more at a measurement temperature of 650° C.

[0197] According to one embodiment, there is provided a method for manufacturing an optical element, the method comprising press-molding a material to be molded using the glass molding die described above.

[0198] In one embodiment, the optical element may be a glass optical element.

[0199] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and includes all modifications within the meaning and scope equivalent to the claims.

[0200] For example, it is of course possible to arbitrarily combine two or more of the aspects described as examples or as preferred ranges in the specification.

Claims

1. A glass molding mold, which is a glass molding mold for molding optical elements, wherein: The glass is aluminosilicate glass, In the glass composition expressed in mol% of the glass, The total content of SiO2 and Al2O3 is more than 77.31%, the total content of SiO2, Al2O3 and MgO is more than 88.0%, and the content of Al2O3 is 12.5% ​​to 24.0%. The molar ratio of the total content of Li2O, Na2O and K2O to the content of MgO (Li2O+Na2O+K2O) / MgO is in the range of 0.000 to 0.

400. The molar ratio of MgO to the total content of MgO, CaO, SrO and BaO (MgO / (MgO+CaO+SrO+BaO)) is 0.600 or more and 1.000 or less, The content of ZnO is 0.0~2.5%, The content of B2O3 is not less than 0.0 mol% and not more than 2.0 mol%.

2. The glass forming mold according to claim 1, wherein: In the glass composition expressed in mol% of the glass, The molar ratio of MgO to the total content of MgO, CaO, SrO and BaO, MgO / (MgO+CaO+SrO+BaO), is 0.650 or more and 1.000 or less.

3. The glass forming mold according to claim 1 or 2, wherein: In the glass composition expressed in mol% of the glass, The molar ratio of the total content of Li2O, Na2O, K2O, SrO and BaO to the total content of SiO2, Al2O3, MgO, CaO, ZrO2 and TiO2 (Li2O+Na2O+K2O+SrO+BaO) / (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2) is in the range of 0.000 to 0.

100.

4. The glass forming mold according to claim 1 or 2, wherein: In the glass composition expressed in mol% of the glass, MgO content is 1.0% to 30.0%, CaO content is 0.0~15.0%, SrO content is 0.0~12.0%, BaO content is 0.0~12.0%, The ZnO content is 0.0-2.5%, Li2O content is 0.0~8.0%, The total content of Na2O and K2O is 0.0~4.25%, ZrO2 content is 0.0~10.0%, The TiO2 content is 0.0-6.0%, and The total content of La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5 and HfO2 is 0.0-4.0%.

5. The glass forming mold according to claim 1 or 2, wherein: The glass has a Young's modulus of 80 GPa or more at a measurement temperature of 590°C.

6. The glass forming mold according to claim 1 or 2, wherein: The glass has a Young's modulus of 80 GPa or more at a measurement temperature of 650°C.

7. A method for producing an optical element, comprising press-molding a material to be molded using the glass molding mold according to any one of claims 1 to 6.

8. The method for manufacturing an optical element according to claim 7, wherein: The optical element is a glass optical element.

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