Glass mold for forming optical elements, method for manufacturing the same, and method for manufacturing optical elements

Abstract

To provide a glass molding die that can reduce variations in shapes of optical elements when producing the optical elements by press molding.SOLUTION: A glass molding die for optical element molding has a Newton variation A590°C of 0.00 or more and 1.50 or less before and after annealing at 590°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a glass molding die for molding optical elements, a method for producing the same, and a method for producing an optical element.

Background Art

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

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] When mass-producing optical elements by press-molding a material to be molded with a molding die, press molding of a plurality of materials to be molded is usually repeated using a single molding die. Low shape variation in optical elements mass-produced in this way is desirable for stably supplying optical elements having desired optical performance to the market.

[0005] An object of one aspect of the present invention is to provide a glass molding die capable of suppressing the occurrence of shape variation in optical elements when mass-producing optical elements by press molding.

Means for Solving the Problem

[0006] One aspect of the present invention is: Newton variation A before and after annealing at a temperature of 590°C 590℃ is 0.00 fringes or more and 1.50 fringes or less, which is a glass molding die for molding optical elements (hereinafter, also simply referred to as "glass molding die" or "molding die"), Regarding.

[0007] As a result of diligent research, the inventors have newly discovered that in order to suppress the occurrence of shape variations in the optical element described above, a glass mold that undergoes little shape change before and after the cooling process, which is normally included in the press molding process of the optical element, should be used. 590℃ This can serve as an indicator of such shape changes, A 590℃ By using a glass mold with a ratio of 0 to 1.5 lines to perform press molding of multiple materials, it becomes possible to mass-produce optical elements with minimal shape variation. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to provide a glass mold that can suppress variations in the shape of optical elements when mass-producing optical elements by press molding. Furthermore, according to one aspect of the present invention, it is also possible to provide a method for manufacturing a glass mold suitable for the manufacture of the above-mentioned glass mold, and a method for manufacturing optical elements using the above-mentioned glass mold. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing an example of a manufacturing apparatus for optical elements, including a glass mold. [Figure 2] This is a schematic cross-sectional view showing an example of a manufacturing apparatus for glass molding dies. [Modes for carrying out the invention]

[0010] [Glass molds for forming optical elements] The glass mold described above will be explained in more detail below. While the following explanation may refer to the drawings, the present invention is not limited to the embodiments shown in the drawings.

[0011] <Composition of glass molding die> Figure 1 is a schematic cross-sectional view of an example of a manufacturing apparatus for optical elements equipped with a glass mold. The optical element manufacturing apparatus 10 in Figure 1 manufactures an optical element 20 from a workpiece 21 by press molding and includes an upper mold 11 and a lower mold 12, which are glass molds. The upper mold 11 and the lower mold 12 are supported within a guide mold 13 so as to be able to move relative to each other, and the distance between them can be changed. The upper mold 11 and the lower mold 12 may both be movable molds, or one may be movable and the other fixed.

[0012] The above glass mold can be an upper mold 11 in one embodiment and a lower mold 12 in another embodiment. In the other embodiment, the upper mold 11 and the lower mold 12 are the Newton change A before and after annealing at a temperature of 590°C. 590℃ The glass mold may have a ratio of 0.00 to 1.50. The glass constituting the upper mold 11 and the lower mold 12 may be the same in one embodiment and different in another embodiment. In a preferred embodiment, both the upper mold 11 and the lower mold 12 have a Newton change A before and after annealing at a temperature of 590°C. 590℃ The glass mold can have between 0.00 and 1.50 strands, and in a more preferred form, the glass constituting the upper mold 11 and the lower mold 12 can be the same glass.

[0013] The upper mold 11 and the lower mold 12 have molding surfaces 14 and 15 on opposite sides. The optical element 20 is specifically a biconvex lens with aspherical surfaces on both sides, and the molding surfaces 14 and 15 are concave surfaces (aspherical surfaces) corresponding to the shapes of the convex surfaces (aspherical surfaces) of the optical element 20. That is, the shapes of the molding surfaces 14 and 15 are transferred by press molding to form the convex surfaces of the optical element 20. However, the embodiment shown in Figure 1 is illustrative, and the molding surfaces of the glass mold may have a convex shape in one embodiment and a concave shape in another embodiment.

[0014] Coatings 16 and 17 are respectively formed on the molding surfaces 14 and 15. The coatings 16 and 17 can be coatings generally called release coatings, for example, they can be carbon films or the like and can play a role in suppressing fusion bonding of a material to be molded. Although the coatings 16 and 17 shown in Fig. 1 have a single-layer structure, a coating with a multi-layer structure composed of different compositions can also be provided. Alternatively, a configuration in which the molding surfaces 14 and 15 are exposed without providing the coatings 16 and 17 is also selectable.

[0015] A heater (not shown) is provided outside the guide mold 13. During molding, heating can be performed by the heater to a molding temperature at which the material 21 to be molded softens.

[0016] In the present invention and the present specification, the term "glass molding die" refers to a portion provided with a molding surface. For example, in Fig. 1, the entire portions of the upper mold 11 and the lower mold 12 excluding the coatings 16 and 17 may be made of glass. Alternatively, only a part 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 the upper mold 11 or the lower mold 12 can also be configured by joining a base portion made of another material such as metal to the glass portion.

[0017] <Newton variation A 590℃ > The Newton variation A before and after annealing of the above glass molding die at a temperature of 590°C 590℃ is 0.00 or more and 1.50 or less. Newton variation A 590℃ is obtained by the following method. The shape of the molding surface of the glass molding die before annealing is measured at room temperature (about 25°C) using a shape measuring instrument. Examples of the shape measuring instrument include an interferometer, a three-dimensional measuring machine (for example, UA3P manufactured by Panasonic Production Engineering Co., Ltd.), and the like. The number of Newton rings when the measurement wavelength is 546.1 nm is calculated from the value of the radius of curvature R of the molding surface (paraxial R for an aspheric molding surface) measured by shape measurement. Thereafter, the glass mold is placed in an annealing furnace, the furnace temperature is increased from room temperature (about 25°C) to a holding temperature of 590°C over 5 hours, held at 590°C for 4 hours, then decreased to a temperature 100°C lower than the holding temperature at a cooling rate of -50°C / hour over 2 hours, then cooled by turning off the power to cool down to room temperature (about 25°C). For the annealed glass mold taken out from the annealing furnace, the number of Newton rings is calculated when the measurement wavelength is set to 546.1 nm. Let the difference in the number of Newton rings between before annealing and after annealing (after annealing - before annealing) be A 590℃ . In addition, Newton variation A, the details of which will be described later 650℃ is obtained by the above method, except that annealing is performed as follows. The furnace temperature of the annealing furnace is increased from room temperature (about 25°C) to a holding temperature of 650°C over 5 hours, held at 650°C for 4 hours, then decreased to a temperature 100°C lower than the holding temperature at a cooling rate of -50°C / hour over 2 hours, then cooled by turning off the power to cool down to room temperature (about 25°C).

[0018] The present inventor considers that the above-mentioned Newton variation A 590℃ is a value that can serve as an indicator that the shape of a glass mold is less likely to change before and after the cooling process normally included in the press molding process of optical elements. More specifically, the present inventor considers that a glass mold having the above-mentioned Newton variation A 590℃ of 0.00 rings or more and 1.50 rings or less has small shape change before and after the cooling process normally included in the press molding process of optical elements, and according to such a mold, when mass-producing optical elements by press molding, it is possible to suppress the occurrence of shape variation in optical elements. From the viewpoint of further suppressing the occurrence of shape variation in optical elements, the Newton variation A of the glass mold 590℃ is preferably 1.00 rings or less, more preferably 0.50 rings or less, and still more preferably 0.25 rings or less. In addition, Newton variation A 590℃ is 0.00 rings or more, and can be, for example, 0.01 rings or more. However, Newton variation A 590℃A smaller value is preferable for suppressing variation in the shape of the optical element, so Newton change amount A 590℃ can be less than 0.01 fringes.

[0019] <Newton change amount A 650℃ > In one embodiment, the glass molding die described above has a Newton change amount A before and after annealing at a temperature of 650°C 650℃ can be a glass molding die of 0.00 fringes or more and 1.50 fringes or less. Newton change amount A 590℃ is within the range described above, and when Newton change amount A 650℃ is 0 fringes or more and 1.50 fringes or less, shape change before and after the cooling step normally included in the press molding process of optical elements is further reduced. The present inventor considers that with such a molding die, when mass-producing optical elements by press molding, it becomes possible to further suppress the occurrence of shape variation in optical elements. From the viewpoint of further suppressing the occurrence of shape variation in optical elements, the Newton change amount A of the glass molding die 650℃ is preferably 1.50 fringes or less, and more preferably in the order of 1.00 fringes or less, 0.50 fringes or less, and 0.25 fringes or less. Further, Newton change amount A 650℃ can be, for example, 0.00 fringes or more or 0.05 fringes or more. Newton change amount A 650℃ A smaller value is preferable for suppressing variation in the shape of the optical element, so Newton change amount A 650℃ can also be less than 0.05 fringes.

[0020] <Rate of change of Newton change amount with respect to temperature> In one embodiment, in the temperature range of 590°C to 650°C, the glass molding die has a rate of change of Newton change amount with respect to temperature of 0.00×10 -2 fringes / °C or more and 4.00×10 -2The glass mold can be less than 10¹⁰ / °C. A small value for the rate of change of the Newtonian change with respect to temperature is preferable from the viewpoint of further suppressing the occurrence of shape variations in optical elements when mass-producing optical elements by press molding. From the above viewpoint, in the glass mold described above, the rate of change of the Newtonian change with respect to temperature in the temperature range of 590°C to 650°C is 4.00 × 10¹⁰. -2 Preferably below 3.50 × 10 -2 It is more preferable that the temperature is below 1 / °C, and 3.00 × 10 -2 It is even more preferable that the temperature be below 2.50 × 10 -2 It is even more preferable that the temperature is below 2.00 × 10 -2 books / ℃ or less, 1.50×10 -2 books / ℃ or less, 1.00×10 -2 The order of preference is increasingly less than 10°C / °C. Furthermore, the rate of change of the Newton change in the above glass mold with respect to the above temperature is 0.00 × 10⁻⁶ -2 It can be above 1 / ℃, or 0.05 × 10 -2 It can be 1 / °C or higher. However, since a small value for the rate of change of the Newtonian change with respect to the above temperature is preferable for suppressing the occurrence of shape variations in the optical element, the rate of change of the Newtonian change with respect to the above temperature is 0.05 × 10 -2 It can also be below 1 / ℃.

[0021] The rate of change of the Newtonian change with respect to the above temperature can be determined by the following method. The Newton change A of the glass mold is determined by the method described above. 590℃ and Newton change A 650℃ We find A. 590℃ and A 650℃ From there, the following formula: The rate of change of the above Newton change = (A 650℃ -A 590℃ ) / (650-590) This allows us to determine the rate of change (in units: barrels / °C) of the above Newton rate of change.

[0022] The various values ​​described above can be controlled by the composition of the glass constituting the glass mold and / or the manufacturing conditions in the manufacturing method of the glass mold. This will be discussed later.

[0023] The glass used to make up the above-mentioned glass mold will be described in more detail below.

[0024] <Glass composition> In the present invention and this specification, the glass composition is expressed on an oxide basis with respect to the cationic components of the glass. Here, "glass composition on an oxide basis" means the glass composition obtained by calculating it assuming that all glass raw materials decompose during melting and exist as oxides in the glass. Unless otherwise specified, the glass composition is expressed on a molar basis (mol%, molar ratio). The various components that make up glass can be quantified using known methods, such as inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). By dividing this elemental content (elemental mass %) by its atomic weight, the content of each element can be determined in mole percent. Furthermore, in the present invention and this specification, a component content of 0% or not present or introduced means that the component is substantially absent, and it is permissible for the component to be present at an unavoidable impurity level.

[0025] The above glass may, in one form, be aluminosilicate glass. In the present invention and this specification, "aluminosilicate glass" means glass in which the glass composition, expressed on an oxide basis for the cation components of the glass, contains at least SiO2 and Al2O3.

[0026] In the above glass, the total content of SiO2 and Al2O3 (SiO2 + Al2O3) can be, for example, 60.0% or more. Having a total content of 60.0% or more (SiO2 + Al2O3) is thought to contribute to reducing the change in Young's modulus with respect to temperature changes, and this is related to the change in Newton's modulus A. 590℃ To reduce the value of, and furthermore, the Newton change A 590℃ The inventors believe that this will lead to a reduction in the value of . From this viewpoint, the total content (SiO2 + Al2O3) is preferably 65.0% or more, and in addition to the above viewpoint, it is preferably 66.0% or more from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, and in addition to the above viewpoint, it is preferably 68.0% or more from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and in addition to the above viewpoint, it is preferably 70.0% or more from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later). On the other hand, the total content (SiO2 + Al2O3) can be, for example, 100.0% or less, preferably 91.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 90.5% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, preferably 90.5% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), preferably 90.5% or less from the viewpoint of increasing the heat resistance of the glass, preferably 90.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0027] The molar ratio of the total content of Li2O, Na2O, and K2O to the MgO content ((Li2O+Na2O+K2O) / MgO) can be, for example, 0.000 or more or greater than 0.000. The molar ratio ((Li2O+Na2O+K2O) / MgO) can be, for example, 0.400 or less, preferably 0.300 or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 0.200 or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 0.150 or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 0.100 or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0028] The molar ratio of MgO content to the total MgO + CaO + SrO + BaO content (MgO / (MgO+CaO+SrO+BaO)) can be, for example, 1.000 or less. The molar ratio (MgO / (MgO+CaO+SrO+BaO)) is preferably 0.500 or more from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 0.550 or more from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press forming process is normally performed, preferably 0.600 or more from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 0.650 or more from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0029] The total content of Li2O+Na2O+K2O (Li2O+Na2O+K2O) can be, for example, 0.0% or more or greater than 0.0%. Furthermore, the total content (Li2O+Na2O+K2O) can be, for example, 4.25% or less. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, the total content (Li2O+Na2O+K2O) is preferably 4.0% or less. In addition to the above viewpoint, from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press forming process is normally performed, it is preferably 3.0% or less. In addition to these viewpoints, from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), it is preferably 2.0% or less. In addition to these viewpoints, from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later), it is preferably 1.0% or less.

[0030] The total content of Na2O and K2O (Na2O + K2O) can be, for example, 0.0% or more, or greater than 0.0%. Furthermore, the total content (Na2O + K2O) can be, for example, 4.25% or less. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes or avoiding excessively large thermal expansion coefficients, the total content (Na2O + K2O) can be, for example, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, or 0.5% or less.

[0031] The total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) can be, for example, 35.0% or less. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, the total content (MgO + CaO + SrO + BaO) is preferably 32.5% or less. In addition to the above viewpoint, from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press forming process is normally performed, it is preferably 30.0% or less. In addition to these viewpoints, from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), it is preferably 27.5% or less. In addition to these viewpoints, from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later), it is preferably 25.0% or less. Furthermore, the total content (MgO + CaO + SrO + BaO) can be, for example, 0.0% or more or 1.0% or more. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, the total content (MgO + CaO + SrO + BaO) is preferably 8.0% or more. In addition to the above viewpoint, from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, it is preferably 8.5% or more. In addition to these viewpoints, from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), it is preferably 9.0% or more. In addition to these viewpoints, from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later), it is preferably 9.5% or more.

[0032] The total content of MgO and CaO (MgO + CaO) can be, for example, 32.5% or less. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, the total content (MgO + CaO) is preferably 30.0% or less. In addition to the above viewpoint, from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, it is preferably 27.5% or less. In addition to these viewpoints, from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), it is preferably 25.0% or less. In addition to these viewpoints, from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later), it is preferably 22.5% or less. Furthermore, the total content (MgO + CaO) can be, for example, 0.0% or more or 1.0% or more. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, the total content (MgO + CaO) is preferably 8.0% or more. In addition to the above viewpoint, from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, it is preferably 8.5% or more. In addition to these viewpoints, from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), it is preferably 9.0% or more. In addition to these viewpoints, from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later), it is preferably 9.5% or more.

[0033] The total content of SiO2, Al2O3, and MgO (SiO2 + Al2O3 + MgO) can be, for example, 100.0% or less or less than 100.0%. Alternatively, the total content (SiO2 + Al2O3 + MgO) can be, for example, 80.0% or more. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, the total content (SiO2 + Al2O3 + MgO) is preferably 85.0% or more. In addition to the above viewpoint, it is preferably 86.0% or more from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed. In addition to these viewpoints, it is preferably 87.0% or more from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature). In addition to these viewpoints, it is preferably 88.0% or more from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α value, as described later).

[0034] The total content of Li2O, Na2O, K2O, SrO, and BaO (Li2O + Na2O + K2O + SrO + BaO) can be, for example, 0.0% or more or greater than 0.0%. Furthermore, the total content (Li2O + Na2O + K2O + SrO + BaO) can be, for example, 4.5% or less, preferably 3.5% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 3.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, preferably 2.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 1.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0035] The total content of SiO2, Al2O3, MgO, CaO, ZrO2, and TiO2 (SiO2 + Al2O3 + MgO + CaO + ZrO2 + TiO2) can be, for example, 100.0% or less or less than 100.0%. Furthermore, the total content (SiO2 + Al2O3 + MgO + CaO + ZrO2 + TiO2) can be, for example, 85.0% or more, preferably 90.0% or more from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 91.0% or more from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 92.0% or more from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 93.0% or more from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0036] 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. Furthermore, the molar ratio ((Li2O+Na2O+K2O) / (MgO+CaO)) can be, for example, 2.000 or less, preferably 0.150 or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 0.100 or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 0.100 or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, preferably 0.050 or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 0.030 or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0037] 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. Furthermore, the molar ratio ((Li2O+Na2O+K2O) / (SiO2+Al2O3+MgO)) can be, for example, 0.050 or less, preferably 0.040 or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 0.030 or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 0.030 or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, preferably 0.020 or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 0.010 or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0038] 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 0.000 or greater, or greater than 0.000. Furthermore, the molar ratio ((Li2O+Na2O+K2O+SrO+BaO) / (SiO2+Al2O3+MgO+CaO+ZrO2+TiO2)) can be, for example, 0.100 or less, preferably 0.090 or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 0.080 or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 0.080 or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, preferably 0.060 or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0039] The total content of La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5, and HfO2 (La2O3+Y2O3+Yb2O3+Ta2O5+Nb2O5+HfO2) can be 0.000% or more, or greater than 0.000%. Furthermore, the total content (La2O3+Y2O3+Yb2O3+Ta2O5+Nb2O5+HfO2) can be, for example, 5.0% or less, and from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes or from the viewpoint of not making the specific modulus too small, it is preferable in the order of 4.0% or less, 3.0% or less, 2.0% or less, and 1.0% or less.

[0040] SiO2 is a skeletal component of glass and is a useful component for reducing the change in Young's modulus due to temperature changes. The SiO2 content is preferably 51.0% or more from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in glass molds, preferably 55.0% or more from the viewpoint of further reducing the change in Young's modulus due to temperature changes, preferably 56.0% or more from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoints, preferably 57.0% or more from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 58.0% or more from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later). Furthermore, the SiO2 content is preferably 79.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold; preferably 76.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes; preferably 75.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, in addition to the above viewpoints; preferably 74.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), in addition to the above viewpoints; and preferably 73.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0041] Al2O3 is a skeletal component of glass and is a useful component for reducing the change in Young's modulus due to temperature changes. The Al2O3 content is preferably 8.0% or more from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in glass molds, preferably 10.0% or more from the viewpoint of further reducing the change in Young's modulus due to temperature changes, preferably 11.0% or more from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoints, preferably 12.0% or more from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 12.5% ​​or more from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later). Furthermore, the Al2O3 content is preferably 24.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold; preferably 22.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes; preferably 21.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, in addition to the above viewpoints; preferably 20.5% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), in addition to the above viewpoints; and preferably 20.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0042] B2O3 is a component that can be optionally included in the glass, for example, to adjust the viscosity of the glass. The B2O3 content can be, for example, 0.0% or more or greater than 0.0%, and from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold, it can be 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more. Furthermore, the B2O3 content is preferably 2.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, and also from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, and also from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and also from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0043] MgO is a component that can contribute to improving the Young's modulus of glass, lowering its specific gravity (and improving its specific modulus by lowering its specific gravity), and / or lowering α as described below. The MgO content can be 0.0% or more, greater than 0.0%, or 1.0% or more. From the viewpoint of suppressing the occurrence of bubbles, striations, and / or undissolved material in the glass mold, it is preferable to have 6.0% or more. From the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, it is preferable to have 8.0% or more. In addition to the above viewpoint, from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, it is preferable to have 8.5% or more. In addition to the above viewpoint, from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), it is preferable to have 9.0% or more. In addition to the above viewpoint, from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described below), it is preferable to have 9.5% or more. Furthermore, the MgO content can be, for example, 30.0% or less, preferably 24.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold, preferably 22.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 21.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, preferably 20.5% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 20.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0044] The CaO content can be 0.0% or more, or greater than 0.0%. CaO is a component that can contribute to improving the Young's modulus of glass and lowering its specific gravity (and improving its specific modulus by lowering its specific gravity), and it is preferable to use it in combination with MgO. The CaO content can be, for example, 15.0% or less, preferably 10.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold and suppressing a decrease in the glass transition temperature, preferably 8.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 7.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoints, preferably 6.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 5.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0045] The SrO content can be 0.0% or more, or greater than 0.0%. SrO is a component that can contribute to adjusting the fusion properties of glass, and by substituting it with alkaline components, it can further reduce the change in Young's modulus with respect to temperature changes. The SrO content can be, for example, 12.0% or less, preferably 6.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold and suppressing a decrease in the Young's modulus of the glass, preferably 5.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 4.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoints, preferably 3.5% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 3.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0046] The BaO content can be 0.0% or more, or greater than 0.0%. BaO is a component that can contribute to adjusting the fusion properties of glass, and by substituting it with an alkaline component, it can further reduce the change in Young's modulus due to temperature changes. The BaO content can be, for example, 12.0% or less, preferably 8.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold and suppressing a decrease in the Young's modulus of the glass, preferably 5.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 4.5% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoints, preferably 4.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 3.8% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0047] The ZnO content can be 0.0% or more, or greater than 0.0%. Keeping the ZnO content below a certain level may contribute to suppressing a decrease in the glass transition temperature and / or a decrease in the specific modulus. The ZnO content can be, for example, 10.0% or less, preferably 5.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold and from the above viewpoint, preferably 4.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 3.5% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 3.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoints, and preferably 2.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0048] The Li2O content can be 0.0% or more, or greater than 0.0%. Keeping the Li2O content below a certain amount may contribute to further reducing the change in Young's modulus with respect to temperature changes, suppressing the decrease in the glass transition temperature, and / or suppressing the decrease in Young's modulus. The Li2O content can be, for example, 8.0% or less, preferably 3.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold and from the above viewpoint, preferably 2.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 1.5% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed in addition to the above viewpoint, preferably 1.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature) in addition to the above viewpoint, and preferably 0.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α as described later).

[0049] The Na2O content can be 0.0% or more, or greater than 0.0%. Keeping the Na2O content below a certain level can contribute to further reducing the change in Young's modulus with respect to temperature changes, suppressing the decrease in the glass transition temperature, and / or suppressing the decrease in Young's modulus. The Na2O content is preferably 3.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes; preferably 2.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, in addition to the above viewpoint; preferably 1.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), in addition to the above viewpoint; and preferably 0.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0050] The K2O content can be 0.0% or more, or greater than 0.0%. Keeping the K2O content below a certain amount can contribute to further reducing the change in Young's modulus with respect to temperature changes, suppressing the decrease in the glass transition temperature, and / or suppressing the decrease in Young's modulus. The K2O content is preferably 3.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes; preferably 2.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, in addition to the above viewpoint; preferably 1.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), in addition to the above viewpoint; and preferably 0.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0051] ZrO2 is a component that can be optionally included in the glass, for example, to improve 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, preferably 4.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold, preferably 2.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 2.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, preferably 1.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 0.5% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0052] TiO2 is a component that can be optionally included in the glass, for example, to improve Young's modulus and / or to suppress the formation of bubbles in the glass mold. The TiO2 content can be, for example, 0.0% or more or greater than 0.0%. From the viewpoint of suppressing the formation of bubbles, striations and / or undissolved material in the glass mold, the TiO2 content can be 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more. Furthermore, the TiO2 content can be, for example, 6.0% or less, preferably 5.0% or less from the viewpoint of suppressing the occurrence of bubbles, striations and / or undissolved material in the glass mold, preferably 4.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature changes, preferably 3.0% or less from the viewpoint of increasing the rigidity of the glass (e.g., Young's modulus) at the temperature at which the press molding process is normally performed, preferably 2.0% or less from the viewpoint of increasing the heat resistance of the glass (e.g., glass transition temperature), and preferably 1.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (e.g., having a low α, as described later).

[0053] From the viewpoint of reducing the change in Young's modulus with respect to temperature changes, the La2O3 content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. The La2O3 content can be 0.0%, 0.0% or more, or greater than 0.0%.

[0054] From the viewpoint of reducing the change in Young's modulus with respect to temperature changes, 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, and may also be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0055] From the viewpoint of reducing the change in Young's modulus with respect to temperature changes, the Yb2O3 content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. The Yb2O3 content may also be 1.0% or less or 0.5% or less, and may also be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0056] From the viewpoint of reducing the change in Young's modulus with respect to temperature changes, the Ta2O5 content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. The Ta2O5 content may also be 1.0% or less or 0.5% or less, and may also be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0057] From the viewpoint of reducing the change in Young's modulus with respect to temperature changes, the Nb2O5 content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. The Nb2O5 content may also be 1.0% or less or 0.5% or less, and may also be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0058] From the viewpoint of reducing the change in Young's modulus with respect to temperature changes, the HfO2 content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less. The HfO2 content may also be 1.0% or less or 0.5% or less, and may also be 0.0% (i.e., not contained), 0.0% or more, or greater than 0.0%.

[0059] SnO2 is a component that can be optionally included in the glass, for example, to improve Young's modulus and / or to suppress the formation of bubbles in the glass mold. The SnO2 content can be, for example, 0.0% or more or greater than 0.0%. From the viewpoint of suppressing the formation of bubbles, striations and / or undissolved material in the glass mold, the SnO2 content can be 0.05% or more, 0.3% or more, or 0.5% or more. Furthermore, 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, from the viewpoint of suppressing the formation of bubbles, striations and / or undissolved matter in the glass mold. The SnO2 content may also be 0.2% or less or 0.1% or less, and may also be 0.0% (i.e., none), 0.0% or more, or greater than 0.0%.

[0060] CeO2 is a component that can be optionally included in the glass, for example, to improve the Young's modulus and / or to suppress the formation of bubbles in the glass mold. The CeO2 content can be, for example, 0.0% or more or greater than 0.0%. From the viewpoint of suppressing the formation of bubbles, striations and / or undissolved material in the glass mold, the CeO2 content can be 0.05% or more, 0.3% or more, or 0.5% or more. Furthermore, 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, from the viewpoint of suppressing the formation of bubbles, striations and / or undissolved matter in the glass mold. The CeO2 content may also be 0.2% or less or 0.1% or less, and may also be 0.0% (i.e., none), 0.0% or more, or greater than 0.0%.

[0061] Sb2O3 is a component that can be optionally included in the glass, for example, to improve Young's modulus and / or to suppress the formation of bubbles in the glass mold. The Sb2O3 content can be, for example, 0.0% or more or greater than 0.0%. From the viewpoint of suppressing the formation of bubbles, striations and / or undissolved material in the glass 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. Furthermore, 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, from the viewpoint of suppressing the formation of bubbles, striations and / or undissolved matter in the glass mold.

[0062] Fe2O3 is a component that can be optionally included in the glass, for example, to improve Young's modulus and / or to suppress the formation of bubbles in the glass mold. The Fe2O3 content can be, for example, 0.0% or more or greater than 0.0%. From the viewpoint of suppressing the formation of bubbles, striations and / or undissolved material in the glass mold, the Fe2O3 content can be 0.05% or more, 0.3% or more, or 0.5% or more. Furthermore, 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, from the viewpoint of suppressing the formation of bubbles, striations and / or undissolved matter in the glass mold.

[0063] <Glass Properties> The glass constituting the above-mentioned glass mold may, in one embodiment, possess one or more of the following glass properties.

[0064] (Glass transition temperature Tg, flexion point Ts) In the present invention and this specification, the glass transition temperature Tg and the bending point Ts of the glass constituting the glass mold described above are values ​​that can be determined by the following method. Glass samples are cut from a glass mold, or glass samples are prepared from the same material as the glass mold. For each glass sample, the thermal expansion properties are measured according to the method specified in JOGIS08-2003. Specifically, the annealing temperature is set by rounding the last digit of the glass's Tg (unit: °C) to the nearest 10°C. The glass sample is placed in an annealing furnace capable of reaching this temperature, heated from room temperature (approximately 25°C) to the set temperature in 1-2 hours, held for 2 hours, then cooled at a rate of -30°C / hour for 4 hours, and then allowed to cool in the furnace to room temperature (approximately 25°C). The glass sample is then processed into a cylindrical glass sample with a diameter of 4.0-5.0 mm and a length of 10-20 mm. A load of 98 mN is applied to this glass sample, and it is heated at a rate of 4°C / minute. The amount of elongation (unit: mm) with respect to temperature is measured every second, and a graph (so-called thermal expansion curve) is created. The temperature corresponding to the intersection of the extensions of the straight lines in the low-temperature and high-temperature regions in the graph above is defined as the glass transition point Tg, and the temperature at which expansion seemingly stops in the graph above, that is, the temperature at the inflection point where the elongation changes from increasing to decreasing with increasing temperature, is defined as the flexing point Ts. For the above glass mold to be suitable for press molding at higher temperatures, the glass transition temperature Tg of the glass is preferably 755°C or higher, more preferably 760°C or higher, even more preferably 765°C or higher, and even more preferably 770°C or higher. Furthermore, the glass transition temperature Tg of the glass can be, for example, 860°C or lower, 855°C or lower, 850°C or lower, 845°C or lower, or 840°C or lower. Furthermore, in order for the above-mentioned glass mold to be a mold suitable for press molding at higher temperatures, the bending point Ts of the glass is preferably 830°C or higher, more preferably 835°C or higher, even more preferably 840°C or higher, and even more preferably 845°C or higher. Also, the bending point Ts of the glass can be, for example, 940°C or lower, 935°C or lower, 930°C or lower, 925°C or lower, or 920°C or lower.

[0065] (Mean coefficient of linear expansion α) For example, as shown in Figure 1, a glass mold can be combined with a guide mold to constitute a manufacturing apparatus for optical elements. From the viewpoint of stress control on the glass mold when combined with such guide molds and other components in the manufacturing apparatus for optical elements, it is preferable to adjust the thermal expansion characteristics of the glass constituting the glass mold. In one embodiment, the thermal expansion characteristics of the glass constituting the glass mold are set to an average linear expansion coefficient α in the temperature range of 100 to 300°C, which is 23.5 × 10⁻⁶. -7 It is preferable that the temperature is above / ℃, and 24.0 × 10 -7 It is more preferable that the temperature is above / ℃, and 24.5 × 10 -7 It is even more preferable that the temperature be above / ℃, 25.0 × 10 -7 It is even more preferable that the temperature is above / ℃. Furthermore, the average coefficient of linear expansion α of the glass is 48.0 × 10 -7 It is preferable that the temperature is below / ℃, and 47.0 × 10 -7 It is more preferable that it be below / ℃, 46.0 × 10 -7 It is even more preferable that it be below / ℃, 45.0 × 10 -7 It is even more preferable that the temperature be below / ℃, 44.0 × 10 -7 It is even more preferable that the temperature be below / ℃. The average linear expansion coefficient α is calculated using the formula: α = d / (L × T), where d is the change in sample length (mm) in the temperature range of 100 to 300°C, L is the initial length of the sample (mm), and T is the temperature difference (K) (300°C - 100°C = 200°C). A thermomechanical analyzer (TMA) or a dilatometer can be used to measure the linear expansion coefficient. The average coefficient of linear expansion α mentioned above can be determined, for example, by the following method. For glass samples cut from a glass mold, or glass samples made from the same material as the glass mold, a thermomechanical analysis (TMA) is used to set the annealing temperature by rounding the last digit of the glass's Tg (in °C) to the nearest 10°C. The glass sample is then placed in an annealing furnace capable of reaching this temperature, heated from room temperature (approximately 25°C) to the set temperature in 1-2 hours, held for 2 hours, then slowly cooled at -30°C / hour for 4 hours, and finally allowed to cool to room temperature (approximately 25°C) in the furnace. This glass sample is then processed into a cylindrical glass sample with a diameter of 4.0-5.0 mm and a length of 10-20 mm. A load of 98 mN is applied to this glass sample, and it is heated at a heating rate of 4°C / min. The elongation (in mm) with respect to temperature is measured every second, and the average linear expansion coefficient α can be determined from the resulting graph (so-called thermal expansion curve).

[0066] In one embodiment, the components of a manufacturing apparatus for optical elements such as guide types can be made of silicon carbide (SiC). SiC has an average coefficient of linear thermal expansion α of 37 × 10⁻⁶. -7 The temperature is approximately / °C. -7When the temperature is " / ℃", it is preferable that X calculated by the formula X=A-37 is a negative value from the viewpoint of suppressing the falling of the optical element during manufacturing. From this viewpoint, it is preferable that X calculated by the above formula for the glass be -13.5 or higher, more preferably -13.0 or higher, even more preferably -12.5 or higher, and even more preferably -12.0 or higher. Furthermore, X can be, for example, 11.0 or lower, 10.0 or lower, 9.0 or lower, 8.0 or lower, or 7.0 or lower, and from the above viewpoint, it is preferable that it be less than 0.0. Furthermore, from the viewpoint of suppressing stress on the glass mold from the SiC component in the manufacturing apparatus for optical elements, the absolute value of X|X| is preferably 13.0 or less, more preferably 12.5 or less, even more preferably 12.0 or less, and even more preferably 11.5 or less. Also, the absolute value of X|X| is preferably 0.0 or more, and even more preferably greater than 0.0.

[0067] (specific gravity) From the viewpoint of adjusting the specific modulus of elasticity, as described later, it is preferable for the glass to have a low specific gravity. The specific gravity of the glass is preferably 2.98 or less, more preferably 2.93 or less, even more preferably 2.88 or less, and even more preferably 2.83 or less. The specific gravity of the glass can also be, for example, 2.35 or more, 2.37 or more, 2.40 or more, or 2.43 or more, and can be lower than the values ​​exemplified here. The specific gravity of the glass can be determined by the Archimedes method for a glass sample cut from a glass mold, or for a glass sample made from the same material as the glass mold.

[0068] (Young's modulus) From the viewpoint of suppressing deformation of the glass mold described above, it is preferable that the glass constituting the glass mold has a high Young's modulus. From this viewpoint, the Young's modulus of the glass is preferably 87.0 GPa or higher, more preferably 88.0 GPa or higher, even more preferably 89.0 GPa or higher, and even more preferably 90.0 GPa or higher. Furthermore, the Young's modulus of the glass can be, for example, 101.0 GPa or less, 100.0 GPa or less, 99.0 GPa or less, 98.0 GPa or less, or 97.0 GPa or less, or it can exceed the values ​​exemplified herein. The Young's modulus of the glass can be determined for a glass sample cut from the glass mold, or for a glass sample made of the same material as the glass mold, at a measurement temperature of 25°C ± 5°C by the ultrasonic pulse method described in JIS R1602:1995. The size of the glass sample can be appropriately set to a size greater than or equal to the minimum dimensions described in JIS R1602:1995.

[0069] (Specific modulus of elasticity) The specific modulus of elasticity is the Young's modulus of glass divided by its density. Here, density is the specific gravity of the glass divided by g / cm³. 3 This can be considered as a value with the unit attached. A mold made from glass with a higher specific modulus of elasticity can be said to be a mold that is lighter and less prone to deformation. From this viewpoint, the specific modulus of elasticity of the glass is preferably 31.0 MNm / kg or more, more preferably 32.0 MNm / kg or more, even more preferably 33.0 MNm / kg or more, and even more preferably 33.5 MNm / kg or more. Furthermore, the specific modulus of elasticity of the glass can be, for example, 41.0 MNm / kg or less, 40.5 MNm / kg or less, 40.0 MNm / kg or less, 39.5 MNm / kg or less, or 39.0 MNm / kg or less, and can exceed the values ​​exemplified here.

[0070] (rigidity) The rigidity modulus of glass represents its resistance to deformation under shear force, and from the viewpoint of suppressing deformation of the glass mold, it is preferable for the glass constituting the glass mold to have a high rigidity modulus. From this viewpoint, the rigidity modulus of the glass can be 33.0 GPa or higher, and is preferably 34.0 GPa or higher, 35.0 GPa or higher, and 36.0 GPa or higher, in that order. 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. The rigidity modulus of the above-mentioned glass can be determined for a glass sample cut from a glass mold, or for a glass sample made from the same material as the glass mold, at a measurement temperature of 25°C ± 5°C using the ultrasonic pulse method described in JIS R1602:1995. The size of the glass sample can be appropriately set to a size greater than or equal to the minimum dimensions described in JIS R1602:1995.

[0071] (Poisson's ratio) The Poisson's ratio of glass is a dimensionless parameter determined from the ratio of Young's modulus to shear modulus. The Poisson's ratio of the glass can be, for example, 0.190 or higher, and is preferably 0.195 or higher, 0.200 or higher, 0.205 or higher, and 0.210 or higher, in that order. Alternatively, the Poisson's ratio of the glass can be, for example, 0.333 or lower, and is preferably 0.300 or lower, 0.290 or lower, 0.280 or lower, 0.270 or lower, and 0.260 or lower, in that order. The Poisson's ratio of the above-mentioned glass can be determined for a glass sample cut from a glass mold, or for a glass sample made from the same material as the glass mold, at a measurement temperature of 25°C ± 5°C using the ultrasonic pulse method described in JIS R1602:1995. The size of the glass sample can be appropriately set to a size greater than or equal to the minimum dimensions described in JIS R1602:1995.

[0072] (Liquidus temperature LT) The liquidus temperature LT can be cited as an indicator of the meltability of glass. From the viewpoint of improving the meltability of glass, the liquidus temperature LT of the glass constituting the glass mold is preferably 1440°C or lower, more preferably 1420°C or lower, even more preferably 1400°C or lower, even more preferably 1380°C or lower, and even more preferably 1360°C or lower. Furthermore, the liquidus temperature LT of the glass can be, for example, 1150°C or higher, 1170°C or higher, 1200°C or higher, or 1230°C or higher, and can also be lower than the values ​​exemplified here.

[0073] In the present invention and this specification, "liquid phase temperature" is determined for a glass sample cut from a glass mold, or for a glass sample made from the same material as the glass mold, by the following method. Approximately 20cc of glass (for example, 50g of glass with a specific gravity of 2.5g / cc) is placed in a platinum crucible and heated in a furnace with an ambient temperature of 1400°C to 1600°C for 15 to 30 minutes until molten. Then, it is cooled to below the glass transition temperature Tg. The cooled glass is moved to a furnace with an ambient temperature T and held in the furnace for 16 hours. After that, the presence or absence of crystal precipitation is determined by observation with an optical microscope (magnification 100x). For each different temperature T (in 10°C increments), the presence or absence of crystal precipitation is determined using the method described above. The lowest temperature T at which no crystal precipitation is observed is defined as the liquidus temperature.

[0074] [Manufacturing method for glass molding molds] The above-mentioned glass molding die can be manufactured as a glass molding die having a concave or convex molding surface by pressing a glass material for glass molding dies with a master die.

[0075] Figure 2 is a schematic cross-sectional view of an example of a glass mold manufacturing apparatus (hereinafter also referred to as "mold manufacturing apparatus"). The mold manufacturing apparatus in Figure 2 includes an upper mold (master mold) 31 having a convex molding surface 34, a lower mold 32, and a guide mold 33. A glass material 41 is pressed 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 material 41, thereby obtaining a glass mold having a concave molding surface. The surface shape of the lower mold 32 may be planar, convex, or concave, and is not particularly limited. In addition, in the mold manufacturing apparatus in Figure 2, the master mold for transferring the surface shape to the glass material and forming the molding surface of the glass mold is the upper mold, but such a master mold can also be arranged as the lower mold.

[0076] The upper mold 31 and the lower mold 32 are supported within a guide mold (also commonly called a "sleeve") 33 so as to be able to move relative to each other, and the distance between them can be changed. Both the upper mold 31 and the lower mold 32 may be movable, or one may be movable and the other fixed.

[0077] A heater (not shown) is provided on the outside of the guide mold 33. During molding, the glass material 41 can be heated by the heater to a molding temperature Ta at which it softens. Ta can be set according to the type of glass material, for example, in the range of 700 to 1000°C, preferably in the range of 750 to 950°C. In one embodiment, Ta can be set to Ta = Ts ± 50°C. In the mold manufacturing apparatus of Figure 2, the upper mold, lower mold, and guide mold are heated together with the glass material by the heater provided on the outside of the guide mold 33.

[0078] The glass material, heated to temperature Ta, is pressed against the master mold surface (the molding surface 34 of the upper mold 31 in Figure 2). The glass material 41 can be pressed by applying a pressing load to it via the upper mold 31 and / or the lower mold 32.

[0079] Subsequently, the glass material 41 is cooled in contact with the master mold surface. The cooling rate C in this cooling process is the average cooling rate from Ta to Tb (described later), and from the viewpoint of increasing the productivity of the glass mold and / or suppressing thermal degradation of the master mold, it is -0.1°C / min or higher, -0.3°C / min or higher, -0.5°C / min or higher, -1.0°C / min or higher, -3.0°C / min or higher, -5.0°C / min or higher, -10.0°C / min or higher, or -15.0°C / min. It can be above -100.0°C / min or lower, -50.0°C / min or lower, -30.0°C / min or lower, -25.0°C / min or lower, -20.0°C / min or lower, -18.0°C / min or lower, -16.0°C / min or lower, -14.0°C / min or lower, -12.0°C / min or lower, -10.0°C / min or lower, -5.0°C / min or lower, -3.0°C / min or lower, or -1.0°C / min or lower. In one configuration, from the viewpoint of increasing productivity, the press load and / or cooling rate may be switched at temperatures Tm above Tb and below Ta. The cooling rate C in this case is determined from the cooling rate Ca (unit: °C / min) from Ta to Tm and the cooling rate Cb (unit: °C / min) from Tm to Tb. C (unit: °C / min) = (Ta - Tb) / {(Ta - Tm) / Ca + (Tm - Tb) / Cb} It can be calculated as follows. It is thought that lowering the cooling rate C in the above cooling process contributes to reducing the change in Young's modulus in response to temperature changes, and this is related to the change in Newton's modulus A. 590℃ To reduce the value of, and furthermore, the Newton change A 590℃ The inventors surmise that this leads to a reduction in the value of A. Therefore, when manufacturing a glass mold from a glass material having a composition that tends to exhibit a relatively large change in Young's modulus with respect to temperature changes, by making the cooling rate C slower, the Newton change A can be reduced. 590℃ The value of can be reduced, and furthermore, the Newton change A 590℃The value of can also be reduced. From this point of view, a preferred cooling rate C is -15°C / min or less, and more preferably -10°C / min or less. After the above cooling, the contact state with the master mold surface is released. In this way, the glass material 41 is press-molded, and a glass mold can be obtained having a concave molded surface formed by transferring the surface shape of the master mold surface (molding surface 34 of the upper mold 31 in Figure 2). The above release of the contact state can be performed at a temperature Tb in which the hardening of the glass has progressed sufficiently. It is preferable that Tb is well below the strain point of the glass, and from this viewpoint, for example, it can be Tg-150°C or less, preferably Tg-160°C or less, more preferably Tg-180°C or less, and even more preferably Tg-200°C or less. From the viewpoint of making it easier for the temperature of the glass mold and / or master mold to follow the cooling rate, Tb can be, for example, 20°C or higher, 50°C or higher, 70°C or higher, 100°C or higher, 150°C or higher, 200°C or higher, 250°C or higher, 300°C or higher, 350°C or higher, or 400°C or higher. Furthermore, it is preferable that Tb be well below the Tg of the glass mold, and from this viewpoint, it can be, for example, 900°C or lower, 800°C or lower, 700°C or lower, 600°C or lower, 550°C or lower, 500°C or lower, 400°C or lower, 350°C or lower, or 300°C or lower. During cooling from Ta to Tb, a pressing load may be continuously applied to the glass material 41 via the upper mold 31 and / or lower mold 32 as appropriate, or the load may be only the weight of the mold itself.

[0080] According to the mold molding apparatus shown in Figure 2, a glass mold having a concave molding surface can be obtained. On the other hand, if the surface shape of the molding surface of the master mold is concave, the concave shape can be transferred to the glass material, thereby obtaining a glass mold having a convex molding surface. The glass mold removed from the mold molding apparatus can be subjected to one or more known post-processes, such as annealing and coating formation.

[0081] The material of the master mold is not particularly limited. From the viewpoint of heat resistance, durability, etc., master molds made of silicon carbide (SiC) or glass are preferred. The master mold can be manufactured by known methods.

[0082] [Manufacturing method for optical elements] One aspect of the present invention relates to a method for manufacturing an optical element, which includes press molding a material to be molded using the glass mold described above.

[0083] Regarding the manufacturing method of the optical element described above, known techniques for manufacturing optical elements by press molding can be applied, except for the use of the glass mold described earlier. An example of an optical element manufacturing apparatus that can be used for press molding is the optical element manufacturing apparatus shown in Figure 1, which was described earlier.

[0084] Examples of optical elements include various lenses such as spherical lenses, aspherical lenses, and microlenses, as well as prisms. Furthermore, the material to be molded can be glass, and the optical elements can be glass optical elements.

[0085] For example, using the above-mentioned glass mold, a glass block processed for press molding (hereinafter referred to as "press-molding glass material") can be press-molded. Examples of press-molding glass materials include glass blocks having a mass equivalent to the mass of a press-molded product, such as a preform for precision press molding or a glass material for obtaining an optical element blank by press molding (press-molding glass gob). Press-molding glass materials are produced through a process of processing a glass molded body. A glass molded body can be produced by heating and melting glass raw materials and molding the resulting molten glass. Examples of processing methods for glass molded bodies include cutting, grinding, and polishing. An optical element blank is a glass molded body having a shape that approximates the shape of the optical element to be manufactured. An optical element blank can be produced by a method such as molding glass to a shape that includes the processing allowance to be removed by processing, in addition to the shape of the optical element to be manufactured. For example, optical element blanks can be manufactured by methods such as the reheat press method, which involves heating and softening a glass material for press molding, or the direct press method, which involves supplying a molten glass mass to a press mold using a known method and then press molding it.

[0086] For example, the shape accuracy of the molding surface of a mold for precision press forming requires several times the shape accuracy required for optical elements. According to the glass mold manufacturing method described above, a glass mold can be manufactured by transferring the surface shape of a master mold with high precision. The glass mold thus obtained is suitable as a mold for precision press forming. However, since excellent shape accuracy of the molding surface is desirable in various press forming processes, the glass mold manufactured by the above manufacturing method is not limited to molds for precision press forming, but is suitable as a mold for various press forming processes.

[0087] The following describes a specific example of a method for obtaining glass optical elements by press molding. A carbon film is coated as a release film on the molding surface of a glass mold and placed inside the optical element manufacturing apparatus. After supplying the press-molded glass material (glass material to be molded) into the optical element manufacturing apparatus, the viscosity of the glass material to be molded is 10 8 dPa·s~10 12 The glass is heated and softened to a temperature equivalent to a viscosity of dPa·s, and then pressed with a mold to transfer the molding surface of the glass mold to the glass material to be molded. The temperature set in the apparatus at this time is called the press temperature. To prevent oxidation of the molding surface, it is preferable to maintain a non-oxidizing atmosphere during molding. After this, the glass mold and the glass material to be molded are cooled to near the glass transition temperature of the glass constituting the glass material to be molded, while maintaining close contact between the molding surface and the glass material to be molded, while applying an appropriate load application schedule (for example, -50°C / min). After that, the optical element manufacturing apparatus can be opened (disassembled) and the molded body (optical element) can be removed. [Examples]

[0088] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

[0089] [Examples 1-5, Comparative Example A] <Glass material for glass molding dies> Glass materials having the glass composition shown in Table 1 were prepared by the following method. To obtain the glass composition shown in Table 1, various oxides, boric acid, carbonates, and sulfates were used as raw materials to introduce each component. The raw materials were weighed and thoroughly mixed to form the blended raw materials. At this time, a total of 200g of each raw material in terms of oxide equivalent was used. The crucible containing the blended raw materials was placed in a glass melting furnace, and the glass was melted, clarified, and homogenized at 1600°C for 3 hours. The molten glass was then poured from the crucible into a preheated mold and shaped. Next, the shaped glass was removed from the mold and placed in an annealing furnace set to a furnace temperature of 750°C, and annealed at a slow cooling rate of -30°C / hour to obtain the glass material.

[0090] [Table 1-1]

[0091] [Table 1-2]

[0092] <Master type> A SiC master mold was prepared as the master mold.

[0093] <Fabrication of glass molds by press molding> For each glass material, press molding was performed using the mold manufacturing apparatus configured as shown in Figure 2, according to the method described above. The glass material was pressed by applying a load while in contact with the master mold surface at a temperature Ta as shown in Table 2, and then cooled to a temperature Tb as shown in Table 1, with the average cooling rate C from temperature Ta to Tb being the cooling rate shown in Table 2. In all of Examples 1 to 5 and Comparative Example A, the cooling rate Ca between Ta and Tm was set to 10°C / min. After the above cooling process, the mold was allowed to cool to room temperature within the mold molding apparatus. Then, the contact with the master mold was released, and the glass mold, on which the surface shape of the master mold had been transferred and the molding surface formed, was removed from the mold manufacturing apparatus. In this way, a glass mold having a concave molding surface was fabricated.

[0094]

Table 2

[0095] [Evaluation of Glass Mold] <Glass Physical Properties> For each glass mold of Examples 1 to 5 and Comparative Example A, various glass physical properties shown in Table 3 were obtained by the method exemplified above, and the results are shown in Table 3.

Table 3

[0096] <Newton change amount A 590℃ , Newton change amount A 650℃ , rate of change of Newton change amount with respect to temperature> For each glass mold of Examples 1 to 5 and Comparative Example A, the Newton change amount A at 590°C, the Newton change amount A at 650°C, and the rate of change of the Newton change amount with respect to temperature were obtained by the method described above, and the results are shown in Table 4. A three-dimensional measuring machine (UA3P, manufactured by Panasonic Production Engineering) was used as the shape measuring instrument.

[0097] [Manufacturing and Evaluation of Optical Elements] It is considered that when mass-producing optical elements by press molding, the smaller the shape change of the molding surface of the glass mold, the more the occurrence of shape variation in optical elements can be suppressed. The degree of change in the shape of the molding surface of a glass mold during mass production of optical elements by press molding can be evaluated by the following method. During a single lens molding cycle, the glass mold is exposed to the press temperature environment, heated, and then cooled to near its glass transition temperature. The shape change of the molded surface of the glass mold primarily occurs at the high press temperature during a single lens molding cycle, and this change is expected to increase with the number of presses. The number of Newton lines is calculated from the shape of the glass mold used for lens molding for a certain number of times (shots) X or more (e.g., 50 shots or more) at a certain press temperature, and its shape before use, using the method described above. A three-dimensional measuring machine (Panasonic Production Engineering Co., Ltd. UA3P) was used as the shape measuring instrument. The difference in the number of Newton lines D (after use - before use) before and after use is divided by the number of shots X to obtain the value D / X, which is the Newton change per shot ΔN. Multiplying this by 100 gives the Newton change per 100 shots, 100D / X. The lower limit of the number of presses X used to calculate ΔN is set to 50 or more, considering the measurement error of ΔN. Regarding the upper limit of X, if X is increased to the point where no further shape changes occur in the glass mold, the apparent ΔN becomes small and may not be suitable for evaluation. Therefore, it is preferable that the upper limit of X be 100 or less, more preferably 80 or less, and even more preferably 60 or less. For example, the Newton change ΔN per shot at 590°C can be calculated by determining the number of Newtons from the shape of the glass mold used for lens molding a certain number of times X (50 ≤ X ≤ 100) at a press temperature of 590°C, and the shape before use, using the method described above. Then, the difference in the number of Newtons before and after lens molding, D (after use - before use), is divided by the number of shots X to obtain the value D / X, which is the "Newton change ΔN per shot at 590°C". The smaller this value, the less change in the shape of the molding surface of the glass mold can be evaluated when mass-producing optical elements by press molding. For Examples 1 to 5 and Comparative Example A, the glass molds having the concave shape described above were used as the upper and lower molds, and precision press molding of glass materials to be molded was performed in the optical element manufacturing apparatus with the configuration shown in Figure 1, according to the method of the specific example described above, to produce glass optical elements (biconvex lenses). This process was repeated at a press temperature of 590°C, with X being the number of shots (50 ≤ X ≤ 60). Subsequently, ΔN = D / X obtained by the above method was multiplied by 100 to calculate 100D / X, which is shown in Table 4 as "the value obtained by multiplying the Newton change amount ΔN per shot at 590°C by 100". The value obtained by multiplying the Newton change ΔN per shot at 590℃ by 100 can be 0.00 or greater, and preferably 1.00 or less, in the order of 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. In the case of Comparative Example A, the change in the molding surface shape of the mold was large, and press molding could not be performed up to the number of shots X, so it is indicated as "Pressing not possible" in Table 4.

[0098] [Table 4]

[0099] Finally, we will summarize each of the aforementioned aspects.

[0100] According to one embodiment, the change in Newtonian values ​​A before and after annealing at a temperature of 590°C 590℃ A glass mold for forming optical elements is provided, having a ratio of 0.00 to 1.50.

[0101] According to the glass molding die described above, when mass-producing optical elements by press molding, it is possible to suppress variations in the shape of the optical elements.

[0102] In one embodiment, the Newton change A of the glass mold before and after annealing at a temperature of 650°C is 650℃ The number can be between 0.00 and 1.50.

[0103] In one embodiment, in the above-mentioned glass mold, the rate of change of the Newtonian change with respect to temperature in the temperature range of 590°C to 650°C is 0.00 × 10⁻⁶ -2 Books / ℃ or higher 4.00×10 -2 It can be below 1 / ℃.

[0104] In one embodiment, in the above-mentioned glass mold, the rate of change of the Newtonian change with respect to temperature in the temperature range of 590°C to 650°C is 0.00 × 10⁻⁶ -2 Books / ℃ or higher 2.50×10 -2 It can be below 1 / ℃.

[0105] In one embodiment, the total content of SiO2 and Al2O3 in the glass composition expressed in mole percent of the above glass can be 60.0% or more.

[0106] In one embodiment, the glass composition expressed in mole percent of the above glass may have an SiO2 content of 51.0-79.0%, an Al2O3 content of 8.0-24.0%, and a total content of MgO, CaO, SrO, and BaO of 1.0-35.0%.

[0107] In one embodiment, the glass may be an aluminosilicate glass, and the glass composition of the glass, expressed in molar percentages, may be: MgO content 1.0-30.0%, CaO content 0.0-15.0%, SrO content 0.0-12.0%, BaO content 0.0-12.0%, ZnO content 0.0-10.0%, Li2O content 0.0-8.0%, total content of Na2O and K2O 0.0-4.25%, ZrO2 content 0.0-10.0%, TiO2 content 0.0-6.0%, and total content of La2O3, Y2O3, Yb2O3, Ta2O5, Nb2O5, and HfO2 0.0-4.0%.

[0108] In one embodiment, in the glass composition expressed in molar percentages of the above glass, the molar ratio of the total content of Li2O, Na2O, and K2O to the total content of SiO2, Al2O3, and MgO ((Li2O+Na2O+K2O) / (SiO2+Al2O3+MgO)) can be in the range of 0.000 to 0.050.

[0109] According to one embodiment, a method for manufacturing a glass mold is provided, comprising pressing a glass material for mold making against the surface of a master mold while in contact with it, and cooling the glass material for mold making while in contact with it, wherein the cooling rate in the cooling is -30.0°C / min or less.

[0110] In one embodiment, the cooling rate in the above cooling process can be -15.0°C / min or less.

[0111] According to one embodiment, a method for manufacturing an optical element is provided, which includes press-molding a material to be molded using the glass mold described above.

[0112] In one embodiment, the optical element can be a glass optical element.

[0113] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. For example, it is certainly possible to arbitrarily combine two or more of the forms described in the specification as examples or preferred scopes.

Claims

1. Change in Newton values ​​A before and after annealing at a temperature of 590°C ５９０℃ A glass mold for forming optical elements, wherein the number of fibers is between 0.00 and 1.

50. In the glass composition expressed in mol% of the aforementioned glass, SiO ２ The content is 51.0-79.0%. Al ２ O ３ The content is 11.0-24.0%. The MgO content is 6.0-30.0%. CaO content is 0.0-7.0%. Li ２ The oxygen content is 0.0-2.0%. Na ２ The oxygen content is 0.0-3.0%. K ２ The oxygen content is 0.0-3.0%. The SrO content is 0.0 to 5.0%, and The glass mold having a BaO content of 0.0 to 5.0%.

2. Change in Newton values ​​A before and after annealing at a temperature of 650°C ６５０℃ The glass mold according to claim 1, wherein the number is 0.00 or more and 1.50 or less. In the glass composition expressed in mol% of the aforementioned glass, SiO ２ the content is 51.0% to 79.0%, Al ２ O ３ The content is 11.0-24.0%. The MgO content is 6.0-30.0%. CaO content is 0.0-7.0%. Li ２ The oxygen content is 0.0-2.0%. Na ２ The oxygen content is 0.0-3.0%. K ２ The oxygen content is 0.0-3.0%. The SrO content is 0.0 to 5.0%, and The glass mold having a BaO content of 0.0 to 5.0%.

3. In the temperature range of 590°C to 650°C, the rate of change of the Newton change with respect to temperature is 0.00 × 10⁻⁶. －２ Books / ℃ or higher 4.00 x 10 －２ A glass mold according to claim 1 or 2, wherein the temperature is 1 / °C or less.

4. In the temperature range of 590°C to 650°C, the rate of change of the Newton change with respect to temperature is 0.00 × 10⁻⁶. －２ Books / ℃ or above 2.50×10 －２ A glass mold according to any one of claims 1 to 3, wherein the temperature is 1 / °C or less.

5. In the glass composition expressed in mol% of the aforementioned glass, SiO ２ and Al ２ O ３ The total content is 60.0% or more. A glass mold according to any one of claims 1 to 4.

6. In the glass composition expressed in mol% of the aforementioned glass, The total content of MgO, CaO, SrO, and BaO is 6.0-35.0%. A glass mold according to any one of claims 1 to 5.

7. The aforementioned glass is aluminosilicate glass. In the glass composition expressed in mol% of the aforementioned glass, The ZnO content is 0.0 to 10.0%. Na ２ O and K ２ The total content with O is 0.0 to 4.25%. ZrO ２ The content is 0.0 to 10.0%. TiO ２ The content is 0.0 to 6.0%, La ２ O ３ , Y ２ O ３ Yb ２ O ３ Ta ２ O ５ , Nb ２ O ５ and HfO ２ The total content is 0.0-4.0%. A glass mold according to any one of claims 1 to 6.

8. In the glass composition expressed in mol% of the aforementioned glass, SiO ２ Al ２ O ３ , and Li relative to the total content of MgO ２ O, Na ２ O, K ２ Molar ratio of total O content (Li ２ O + Na ２ O+K ２ O) / (SiO ２ +Al ２ O ３ A glass mold according to any one of claims 1 to 7, wherein the amount of (+MgO) is in the range of 0.000 to 0.

050.

9. A method for manufacturing a glass mold according to any one of claims 1 to 8, Pressing a molded glass material heated to temperature Ta against the surface of a master mold, Cooling the glass material for the mold to the temperature Tb while in contact with the aforementioned state, To release the contact state at the aforementioned temperature Tb, Includes, A method for manufacturing a glass mold, wherein the average cooling rate during cooling from temperature Ta to temperature Tb is -30.0°C / min or less.

10. The method for manufacturing a glass mold according to claim 9, wherein the average cooling rate is -15.0°C / min or less.

11. Press-molding the material to be molded using a glass mold described in any one of claims 1 to 8, A method for manufacturing optical elements, including

12. The method for manufacturing an optical element according to claim 11, wherein the optical element is a glass optical element.

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