CN114751641A - Glass molding die for molding optical element, method for manufacturing glass molding die, and method for manufacturing optical element - Google Patents

Abstract

[ problem ] to]To provide a glass molding die for molding an optical element, a method for manufacturing the glass molding die, and a method for manufacturing an optical element, the glass molding die being mass-produced by press moldingIn the case of an optical element, the occurrence of shape variations in the optical element can be suppressed. [ solution means ] to]A glass-made molding die for molding an optical element, wherein the change A of Newton's rings before and after annealing at a temperature of 590 DEG C_590℃The number of the strands is 0.00 to 1.50.

Description

Glass-made mold for molding optical element, method for producing the same, and method for producing optical element

technical field

The present invention relates to a glass-made mold for molding an optical element, a method for producing the same, and a method for producing an optical element.

Background technique

As a manufacturing method of optical elements, such as a lens, the method of press-molding a to-be-molded material with a molding die is widely used. Patent Document 1 discloses a glass-made mold as a mold that can be used in this production method.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2019-127425

SUMMARY OF THE INVENTION

The problem to be solved by the invention

When mass-producing an optical element by press-molding a material to be molded with a molding die, usually, a plurality of molding materials are repeatedly press-molded using one molding die. From the viewpoint of stably supplying optical elements having desired optical properties to the market, it is preferable that such mass-produced optical elements have less shape variation.

An object of one aspect of the present invention is to provide a glass-made mold capable of suppressing the occurrence of shape deviation in optical elements when mass-producing optical elements by press molding.

means of solving problems

One aspect of the present invention relates to a glass-made mold for optical element molding (hereinafter also abbreviated as "glass-made mold" or "molding mold"), in which Newton rings before and after annealing at a temperature of 590° C. The amount of change A _590°C is 0.00 or more and 1.50 or less.

As a result of repeated intensive studies, the present inventors have newly discovered that in order to suppress the occurrence of the above-mentioned shape deviation of the optical element, it is necessary to use a glass product with less shape change before and after the cooling process usually included in the press molding process of the optical element. mold. In addition, the above-mentioned A _590°C can be used as an index of this shape change, and by using a glass-made molding die having an A _590°C of 0 or more and 1.5 or less to perform press molding of a plurality of to-be-molded materials, it is possible to mass-produce optics with little shape variation. element.

effect of invention

According to one aspect of the present invention, it is possible to provide a glass-made mold capable of suppressing shape deviation of the optical element when mass-producing the optical element by press molding. Moreover, according to one aspect of this invention, the manufacturing method of the glass-made mold suitable for manufacture of the said glass-made mold, and the manufacturing method of the optical element using the said glass-made mold can be provided.

Description of drawings

FIG. 1 is a schematic cross-sectional view showing an example of an optical element manufacturing apparatus including a glass-made mold.

FIG. 2 is a schematic cross-sectional view showing an example of a manufacturing apparatus of a glass-making mold.

Detailed ways

[Glass Molding Mold for Optical Element Molding]

Hereinafter, the above-mentioned glass forming mold will be described in more detail. The following description may be made with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

<Constitution of a glass mold>

FIG. 1 is a schematic cross-sectional view of an example of an optical element manufacturing apparatus including a glass-made mold. The manufacturing apparatus 10 for optical elements of FIG. 1 is a manufacturing apparatus which manufactures the optical element 20 from the to-be-molded material 21 by press molding, and is provided with the upper mold|type 11 and the lower mold|type 12 which are glass-made molding dies. The upper mold|type 11 and the lower mold|type 12 are supported in the guide mold|type 13 so that a relative movement is possible, and the mutual space|interval can be changed. Both the upper mold 11 and the lower mold 12 may be movable movable molds, or one may be a movable mold and the other may be a stationary mold that does not move.

The above-mentioned glass forming mold may be the upper mold 11 in one embodiment, and the lower mold 12 in another embodiment. In addition, in another form, the upper mold|type 11 and the lower mold|type 12 may be glass-made molds whose Newton ring change amount A _{590 degreeC} before and after annealing at 590 degreeC is 0.00 or more and 1.50 or less. The glass constituting the upper mold 11 and the lower mold 12 may be the same glass in one aspect, or different glass in another aspect. In a preferred form, the two forming molds of the upper mold 11 and the lower mold 12 may be glass-made molds with a Newton ring change A before and after annealing at a temperature of 590° C. at _{590° C.} of 0.00 or more and 1.50 or less, In a more preferable form, the glass constituting the upper mold 11 and the lower mold 12 may be the same glass.

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 lenticular lens whose both surfaces are aspherical, and the molding surface 14 and the molding surface 15 are concave surfaces (aspherical surfaces) of shapes corresponding to the respective convex surfaces (aspherical surfaces) of the optical element 20 . That is, the shapes of the molding surface 14 and the molding surface 15 are transferred by press molding to form the convex surface of the optical element 20 . However, the embodiment shown in FIG. 1 is merely an example, and the molding surface of the above-mentioned glass-forming mold has a convex shape in one aspect and a concave shape in another aspect.

Coating films 16 and 17 are formed on the molding surfaces 14 and 15, respectively. The films 16 and 17 may be a film generally called a release film, for example, a carbon film or the like, and can play a role of suppressing thermal sticking of the material to be molded. Although the films 16 and 17 shown in FIG. 1 have a single-layer structure, a film of a multilayer structure with different compositions may be provided. Alternatively, a configuration in which the coating films 16 and 17 are not provided and the molding surfaces 14 and 15 are exposed may be selected.

A heater (not shown) is provided outside the guide die 13 . During molding, a heater may be used to heat to a molding temperature at which the material 21 to be molded is softened.

In the present invention and this specification, the "glass-forming mold" refers to a portion having a molding surface. For example, in FIG. 1 , the entire portions of the upper mold 11 and the lower mold 12 excluding the coating films 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 a base part made of another material such as metal may be joined to the glass part to constitute the upper mold 11 and lower die 12.

<Newton's ring change A _590℃ >

The amount of Newton's ring change A _590°C before and after annealing of the glass-forming mold at a temperature of 590°C is 0.00 or more and 1.50 or less.

The amount of Newton's ring change A _590°C was obtained by the following method.

At room temperature (about 25° C.), the shape of the molding surface of the glass-forming mold before annealing was measured using a shape measuring device. As a shape measuring apparatus, an interferometer, a three-dimensional measuring machine (for example, UA3P by Panasonic Production Engineering), etc. are mentioned. The number of Newton rings when the measurement wavelength was set to 546.1 nm was calculated from the value of the curvature radius R of the molding surface (paraxial R for the aspherical molding surface) measured by shape measurement.

After that, place the glass mold in an annealing furnace, and the temperature in the furnace was raised from room temperature (about 25°C) to a holding temperature of 590°C in 5 hours. After cooling down to a temperature of -100°C holding temperature at a cooling rate of °C/hour, it was cooled down to room temperature (about 25°C) by power-off cooling.

The number of Newton rings when the measurement wavelength was set to 546.1 nm was calculated for the annealed glass-forming mold taken out from the annealing furnace.

The difference in the number of Newton rings before and after annealing (after annealing - before annealing) was defined as A _590°C .

In addition, the amount of Newton's ring change A _650°C , which will be described later in detail, was obtained by the above-described method, except that annealing was performed as follows.

The furnace temperature of the annealing furnace was raised from room temperature (about 25°C) to the holding temperature of 650°C in 5 hours. After holding the temperature at 650°C for 4 hours, it took 2 hours to cool down to the holding temperature at a cooling rate of -50°C/hour - The temperature of 100°C was then cooled down to room temperature (about 25°C) by power-off cooling.

The present inventors considered that the above-mentioned Newton's ring change amount A _590°C is a value that can be used as an index that the glass forming mold is less likely to change in shape before and after the cooling process usually included in the press-molding process of optical elements. More specifically, the present inventors considered that the glass-making mold having the above-mentioned Newton's ring change amount A _590°C of 0.00 or more and 1.50 or less has less shape change before and after the cooling process usually included in the compression molding process of optical elements, According to such a molding die, when the optical element is mass-produced by press molding, it is possible to suppress the occurrence of shape deviation of the optical element. From the viewpoint of further suppressing the shape deviation of the optical element, the amount of Newton's ring change A _590°C of the glass forming mold is preferably 1.00 or less, more preferably 0.50 or less, and still more preferably 0.25 or less. In addition, the amount of Newton's ring change A _590°C may be 0.00 or more, for example, 0.01 or more. Among them, the value of the Newton ring change amount A _590°C is preferably small from the viewpoint of suppressing the shape deviation of the optical element. Therefore, the Newton ring change amount A _590°C may be less than 0.01.

<Newton's ring change A _650℃ >

In one form, the above-mentioned glass-made mold may be a glass-made mold in which the Newton's ring change A _650°C before and after annealing at a temperature of 650°C is 0.00 or more and 1.50 or less. The present inventors consider that when the Newton ring change amount A _590°C is within the range described above and the Newton ring change amount A _650°C is 0 to 1.50, the process of cooling is usually included in the press molding process of optical elements before and after the cooling process. There is less variation in shape, and according to this molding die, when an optical element is mass-produced by press molding, it is possible to further suppress the shape deviation of the optical element. From the viewpoint of further suppressing the shape deviation of the optical element, the amount of Newton's ring change A _650°C of the glass forming mold is preferably 1.50 or less, more preferably 1.00 or less, 0.50 or less, and 0.25 or less in this order. In addition, the amount of Newton's ring change A _650°C may be, for example, 0.00 or more or 0.05 or more. From the viewpoint of suppressing the shape deviation of the optical element, the value of the Newton ring change amount A _650°C is preferably small, so the Newton ring change amount A _650°C may be less than 0.05 bars.

<The rate of change of the amount of change in Newton's ring relative to the temperature>

In one embodiment, the above-mentioned glass forming mold may have a rate of change of the amount of Newton's ring change with respect to temperature in the temperature range of 590°C to 650°C of 0.00×10 ^-2 bars/°C or more 4.00×10 ^-2 bars/ Glass molds below ℃. It is preferable that the value of the change rate of the above-mentioned Newton's ring change amount with respect to the temperature is small from the viewpoint of further suppressing the occurrence of shape deviation of the optical element when mass-producing the optical element by press molding. From the above point of view, in the above-mentioned glass forming mold, in the temperature range of 590°C to 650°C, the rate of change of the amount of Newton's ring change with respect to temperature is preferably 4.00×10 ⁻² bars/°C or less, and more preferably 3.50 ×10 ⁻² /°C or less, more preferably 3.00 × 10 ⁻² /°C or less, more preferably 2.50 × 10 ⁻² /°C or less, still more preferably 2.00 × 10 ⁻² /°C or less, 1.50 ×10 ^-2 bars/°C or less, 1.00×10 ^-2 bars/°C or less. In addition, the rate of change of the Newton ring change amount with respect to the temperature of the glass forming mold may be 0.00×10 ⁻² bars/°C or higher, or 0.05×10 ⁻² bars/°C or higher. Among them, it is preferable that the value of the rate of change of the amount of Newton's ring change with respect to temperature is small from the viewpoint of suppressing the shape deviation of the optical element, so the rate of change of the amount of change of Newton's ring with respect to temperature may be less than 0.05×10 ⁻² bar/°C.

The rate of change of the above-mentioned Newton's ring change amount with respect to temperature is obtained by the following method.

By the method described above, the amount of Newton's ring change A _590°C and the amount of Newton's ring change A _650°C of the glass-making mold were determined. From the obtained A _{590° C.} and A _{650° C.} , the rate of change (unit: bar/° C.) of the above-mentioned Newton’s ring change amount was obtained by the following formula.

The rate of change of the above-mentioned Newton's ring variation = (A _650°C -A _590°C )/(650-590)

The various values described above can be controlled by the composition of the glass constituting the glass forming mold and/or the manufacturing conditions in the manufacturing method of the glass forming mold. This point will be described later.

Hereinafter, the glass constituting the above-mentioned glass-making mold will be described in more detail.

<Glass composition>

In the present invention and the present specification, the glass composition refers to the cationic component of the glass on an oxide basis. Here, the "glass composition based on oxides" refers to the glass composition obtained by converting all the glass raw materials to be decomposed at the time of melting and to exist in the glass as oxides. In addition, unless otherwise stated, the glass composition is shown on a molar basis (mol %, molar ratio).

Regarding the various components constituting the glass, the content (elements) of the elements contained in the glass can be determined by known methods such as inductively coupled plasma optical emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), and the like. %) for quantification. The content of each element in mol % can be obtained by dividing the content of the element (mass % of the element) by the atomic weight.

In addition, in the present invention and the present specification, the content of a constituent component is 0% or not included or not incorporated means that the constituent component is not substantially contained, and the constituent component is allowed to be included at an unavoidable impurity level.

In one form, the glass may be an aluminosilicate glass. In the present invention and the present specification, "aluminosilicate glass" refers to a glass in which at least SiO ₂ and Al ₂ O ₃ are contained in the glass composition on the oxide basis as the cationic components of the glass.

In the above glass, the total content of SiO ₂ and Al ₂ O ₃ (SiO ₂ +Al ₂ O ₃ ) may be, for example, 60.0% or more. The present inventors believe that the total content (SiO ₂ +Al ₂ O ₃ ) of 60.0% or more helps to reduce the change in Young's modulus with respect to the temperature change, which leads to a reduction in the value of the Newton's ring change amount A _590°C , Furthermore, the value of Newton's ring change amount A _590°C is decreased. From this point of view, the total content (SiO ₂ +Al ₂ O ₃ ) is preferably 65.0% or more, and in addition to the above point, the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed is improved. ), it is preferably 66.0% or more, and on the basis of these aspects, from the point of view of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 68.0% or more, and on the basis of these aspects, from From the viewpoint of improving the thermal expansion characteristics of the glass (for example, α to be described later is low), it is preferably 70.0% or more.

On the other hand, the total content (SiO ₂ +Al ₂ O ₃ ) may be, for example, 100.0% or less, and is preferably 91.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature change. From the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 90.5% or less, and on the basis of these points, from the viewpoint of improving the heat resistance (for example, the Young's modulus) of the glass In terms of glass transition temperature), it is preferably 90.5% or less, and in addition to these points, it is preferably 89.5% or less in view of improving the thermal expansion characteristics of glass (eg, low α described later).

The molar ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the MgO content ((Li ₂ O+Na ₂ O+K ₂ O)/MgO) may be, for example, 0.000 or more or more than 0.000. The molar ratio ((Li ₂ O+Na ₂ O+K ₂ O)/MgO) may be, for example, 0.400 or less, and is preferably 0.300 or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature change. In addition to the above, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 0.200 or less, and on the basis of these aspects, the heat resistance ( For example, in terms of glass transition temperature), it is preferably 0.150 or less, and in addition to these points, it is preferably 0.100 or less in terms of improving the thermal expansion characteristics of glass (eg, low α described later).

The molar ratio of the MgO content to the total content of MgO+CaO+SrO+BaO (MgO/(MgO+CaO+SrO+BaO)) may 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 the temperature change. In addition to the above, from the viewpoint of improving the molding process in general The rigidity (for example, Young's modulus) of the glass at the temperature of the molding step is preferably 0.550 or more, and in addition to these points, the heat resistance (for example, the glass transition temperature) of the glass is improved, It is preferable that it is 0.600 or more, and it is preferable that it is 0.650 or more from the point of improving the thermal expansion characteristic of glass (for example, α mentioned later is low) in addition to these points.

The total content of Li ₂ O+Na ₂ O+K ₂ O (Li ₂ O+Na ₂ O+K ₂ O) may be, for example, 0.0% or more or more than 0.0%. In addition, the total content (Li ₂ O+Na ₂ O+K ₂ O) may be, for example, 4.25% or less. The total content (Li ₂ O+Na ₂ O+K ₂ O) is preferably 4.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature change. From the viewpoint of the rigidity (for example, Young's modulus) of the glass at the temperature of the press forming step, it is preferably 3.0% or less, and in addition to these points, from the viewpoint of improving the heat resistance (for example, the glass transition temperature) of the glass From this point of view, it is preferably 2.0% or less, and in addition to these points, it is preferably 1.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later).

The total content of Na ₂ O and K ₂ O (Na ₂ O+K ₂ O) may be, for example, 0.0% or more or more than 0.0%. In addition, the total content (Na ₂ O+K ₂ O) may be, for example, 4.25% or less. The total content (Na ₂ O+K ₂ O) may be, for example, 4.0% or less, 3.0% or less, or 2.0% in order to further reduce the change in Young's modulus with temperature change or to prevent the thermal expansion coefficient from becoming too large. or less, 1.0% or less, or 0.5% or less.

The total content of MgO, CaO, SrO and BaO (MgO+CaO+SrO+BaO) may be, for example, 35.0% or less. The total content (MgO+CaO+SrO+BaO) is preferably 32.5% or less from the viewpoint of further reducing the change in Young's modulus with respect to the temperature change, and in addition to the above-mentioned aspect, from the viewpoint of increasing the amount of the compression molding process usually performed From the viewpoint of the rigidity (for example, Young's modulus) of the glass at temperature, it is preferably 30.0% or less, and from the viewpoint of improving the heat resistance (for example, the glass transition temperature) of the glass in addition to these points, it is preferably 27.5% or less is preferably 25.0% or less from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later) in addition to these points.

In addition, the total content (MgO+CaO+SrO+BaO) may be, for example, 0.0% or more or 1.0% or more. The total content (MgO+CaO+SrO+BaO) is preferably 8.0% or more from the viewpoint of further reducing the change in Young's modulus with respect to the temperature change, and in addition to the above-mentioned aspect, from the viewpoint of increasing the amount of the compression molding process usually carried out From the viewpoint of the rigidity (for example, Young's modulus) of the glass at temperature, it is preferably 8.5% or more, and from the viewpoint of improving the heat resistance (for example, the glass transition temperature) of the glass in addition to these points, it is preferably In addition to these points, 9.0% or more is preferably 9.5% or more from the viewpoint of improving the thermal expansion characteristics of the glass (for example, α to be described later is low).

The total content of MgO and CaO (MgO+CaO) may be, for example, 32.5% or less. The total content (MgO+CaO) is preferably 30.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to the temperature change. In addition to the above, the glass at the temperature at which the press-molding step is usually carried out is improved. From the viewpoint of the rigidity (for example, Young's modulus) of the glass, it is preferably 27.5% or less, and on the basis of these aspects, from the viewpoint of improving the heat resistance (for example, the glass transition temperature) of the glass, it is preferably 25.0% or less, In addition to these points, it is preferable that it is 22.5% or less from the point of improving the thermal expansion characteristic of glass (for example, α mentioned later is low).

In addition, the total content (MgO+CaO) may be, for example, 0.0% or more or 1.0% or more. The total content (MgO+CaO) is preferably 8.0% or more from the viewpoint of further reducing the change in Young's modulus with respect to the temperature change. In addition to the above, the glass at the temperature at which the press forming process is usually carried out is improved. From the viewpoint of the rigidity (for example, Young's modulus) of glass, it is preferably 8.5% or more, and on the basis of these points, from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 9.0% or more, In addition to these points, from the viewpoint of improving the thermal expansion characteristics of the glass (for example, α to be described later is low), the content is preferably 9.5% or more.

The total content of SiO ₂ , Al ₂ O ₃ and MgO (SiO ₂ +Al ₂ O ₃ +MgO) may be, for example, 100.0% or less or less than 100.0%. In addition, the total content (SiO ₂ +Al ₂ O ₃ +MgO) may be, for example, 80.0% or more. The total content (SiO ₂ +Al ₂ O ₃ +MgO) is preferably 85.0% or more from the viewpoint of further reducing the change in Young's modulus with respect to the temperature change. The rigidity (for example, Young's modulus) of the glass at the temperature of the process is preferably 86.0% or more, and in addition to these points, the heat resistance (for example, the glass transition temperature) of the glass is improved, It is preferably 87.0% or more, and in addition to these points, it is preferably 88.0% or more from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later).

The total content of Li ₂ O, Na ₂ O, K ₂ O, SrO and BaO (Li ₂ O+Na ₂ O+K ₂ O+SrO+BaO) may be, for example, 0.0% or more or more than 0.0%.

In addition, the total content (Li ₂ O + Na ₂ O + K ₂ O + SrO + BaO) may be, for example, 4.5% or less, and is preferably 3.5% or less from the viewpoint of further reducing the change in Young's modulus with temperature change. On the basis of the above aspects, from the viewpoint of improving the rigidity (eg Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 3.0% or less. On the basis of these aspects, from the viewpoint of improving the glass From the viewpoint of the heat resistance of glass (eg, glass transition temperature), it is preferably 2.0% or less, and in addition to these aspects, from the viewpoint of improving the thermal expansion characteristics of the glass (eg, low α described later), it is preferably 1.0% the following.

The total content of SiO ₂ , Al ₂ O ₃ , MgO, CaO, ZrO ₂ and TiO ₂ (SiO ₂ +Al ₂ O ₃ +MgO+CaO+ZrO ₂ +TiO ₂ ) may be, for example, 100.0% or less or less than 100.0%. In addition, the total content (SiO ₂ +Al ₂ O ₃ +MgO+CaO+ZrO ₂ +TiO ₂ ) may be, for example, 85.0% or more, and is preferably 90.0 from the viewpoint of further reducing the change in Young's modulus with temperature change. % or more, in addition to the above, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, preferably 91.0% or more, in addition to these aspects, from In terms of improving the heat resistance of the glass (eg, glass transition temperature), it is preferably 92.0% or more, and in addition to these aspects, in terms of improving the thermal expansion characteristics of the glass (eg, low α described later), it is preferably 92.0% or more. 93.0% or more.

The molar ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of MgO and CaO ((Li ₂ O+Na ₂ O+K ₂ O)/(MgO+CaO)) may be, for example, 0.000 above or greater than 0.000. In addition, the molar ratio ((Li ₂ O+Na ₂ O+K ₂ O)/(MgO+CaO)) may be, for example, 2.000 or less, and from the viewpoint of further reducing the change in Young's modulus with temperature change, it is preferably 0.150 or less is preferably 0.100 or less from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, in addition to the above-mentioned aspects. From the viewpoint of the heat resistance of the glass (eg, glass transition temperature), it is preferably 0.050 or less, and from the viewpoint of improving the thermal expansion characteristics of the glass (eg, low α, which will be described later), it is preferably 0.030 or less. .

Molar ratio of the total content of Li ₂ O+Na ₂ O+K ₂ O to the total content of SiO ₂ +Al ₂ O ₃ +MgO ((Li ₂ O+Na ₂ O+K ₂ O)/(SiO ₂ + Al ₂ O ₃ +MgO)) may be, for example, 0.000 or more or more than 0.000. In addition, the molar ratio ((Li ₂ O+Na ₂ O+K ₂ O)/(SiO ₂ +Al ₂ O ₃ +MgO)) may be, for example, 0.050 or less, so as to further reduce the change in Young's modulus with respect to temperature change From the point of view, it is preferably 0.040 or less, and in addition to the above-mentioned aspects, from the point of view of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 0.030 or less. In these points On the basis of , from the viewpoint of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 0.020 or less, and on the basis of these points, from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later) From the starting point, it is preferably 0.010 or less.

The molar ratio of the total content of Li ₂ O+Na ₂ O+K ₂ O+SrO+BaO to the total content of SiO ₂ +Al ₂ O ₃ +MgO+CaO+ZrO ₂ +TiO ₂ ((Li ₂ O+Na ₂ O+K ₂ O+SrO+BaO)/(SiO ₂ +Al ₂ O ₃ +MgO+CaO+ZrO ₂ +TiO ₂ )) may be 0.000 or more or more than 0.000. In addition, the molar ratio ((Li ₂ O+Na ₂ O+K ₂ O+SrO+BaO)/(SiO ₂ +Al ₂ O ₃ +MgO+CaO+ZrO ₂ +TiO ₂ )) may be, for example, 0.100 or less, ranging from From the viewpoint of further reducing the change in Young's modulus with respect to temperature change, it is preferably 0.090 or less, and in addition to the above, the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed is improved. From the viewpoints of , it is preferably 0.080 or less. On the basis of these aspects, from the viewpoint of improving the heat resistance (eg glass transition temperature) of the glass, it is preferably 0.060 or less. On the basis of these aspects, from the viewpoint of improving the glass transition temperature From the viewpoint of thermal expansion characteristics (for example, α described later is low), it is preferably 0.050 or less.

Total content of La ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ and HfO ₂ (La ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ +Ta ₂ O ₅ +Nb ₂ O ₅ +HfO ₂ ) may be 0.000% or more or more than 0.000%. In addition, the total content (La ₂ O ₃ +Y ₂ O ₃ +Yb ₂ O ₃ +Ta ₂ O ₅ +Nb ₂ O ₅ +HfO ₂ ) may be, for example, 5.0% or less, so as to further reduce Young's change with respect to temperature change From the viewpoint of changing the modulus or not to make the specific modulus too small, 4.0% or less, 3.0% or less, 2.0% or less, and 1.0% or less are preferred in this order.

SiO ₂ is a skeleton component of glass, and is a useful component for reducing the change in Young's modulus with respect to temperature change. The SiO ₂ content is preferably 51.0% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold, and from the viewpoint of further reducing the change in Young's modulus with temperature change, it is preferable 55.0% or more, in addition to the above, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 56.0% or more, and in addition to these aspects , from the viewpoint of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 57.0% or more, and on the basis of these aspects, from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later), Preferably it is 58.0% or more.

In addition, the SiO ₂ content is preferably 79.0% or less from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass-making mold, and from the viewpoint of further reducing the change in Young's modulus with temperature change, 76.0% or less is preferable, and 75.0% or less is preferable from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press-molding process is usually performed in addition to the above-mentioned aspects. Above, from the viewpoint of improving the heat resistance of the glass (eg, glass transition temperature), it is preferably 74.0% or less, and in addition to these aspects, from the viewpoint of improving the thermal expansion characteristics of the glass (eg, low α described later) , preferably 73.0% or less.

Al ₂ O ₃ is a skeleton component of glass, and is a useful component for reducing the change in Young's modulus with temperature change. The Al ₂ O ₃ content is preferably 8.0% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold, and from the viewpoint of further reducing the change in Young's modulus with temperature change, 10.0% or more is preferable, and 11.0% or more is preferable from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press-molding process is usually performed in addition to the above points. Above, from the viewpoint of improving the heat resistance of the glass (for example, glass transition temperature), it is preferably 12.0% or more, and on the basis of these viewpoints, from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later) , preferably 12.5% or more.

In addition, the Al ₂ O ₃ content is preferably 24.0% or less from the viewpoint of suppressing generation of bubbles, striae, and/or undissolved matter in the glass-making mold, and from the viewpoint of further reducing the change in Young's modulus with temperature change From the viewpoint, it is preferably 22.0% or less, and in addition to the above-mentioned aspects, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 21.0% or less. In addition to this, from the viewpoint of improving the heat resistance of the glass (eg, glass transition temperature), it is preferably 20.5% or less, and on the basis of these aspects, from the viewpoint of improving the thermal expansion characteristics of the glass (eg, low α described later) From an aspect, it is preferably 20.0% or less.

B ₂ O ₃ is a component optionally contained in the above-mentioned glass, for example, in order to adjust the viscosity of the glass. The content of B ₂ O ₃ may be, for example, 0.0% or more or 0.0%, and may be 0.1% or more, 0.3% or more, or 0.5% from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold above or above 1.0%.

In addition, the content of B ₂ O ₃ is preferably 2.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to the temperature change. In addition to the above, the glass at the temperature at which the press-molding step is usually performed is improved. 2.0% or less is also preferable from the viewpoint of the rigidity (for example, Young's modulus) of glass, and 2.0% is also preferable from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass in addition to these points. Hereinafter, in addition to these points, from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later), the content is preferably 2.0% or less.

MgO is a component which can contribute to the improvement of the Young's modulus of glass, the reduction of specific gravity (and the improvement of specific modulus by reducing specific gravity), and/or the reduction of (alpha) mentioned later. The MgO content may be 0.0% or more, more than 0.0%, or 1.0% or more, but is preferably 6.0% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass-making mold, and from the viewpoint of further reducing the relative temperature From the viewpoint of changing Young's modulus, it is preferably 8.0% or more, and in addition to the above, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, It is preferably 8.5% or more, and in addition to these points, from the point of view of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 9.0% or more, and in addition to these points, in order to improve the thermal expansion characteristics of the glass (For example, α described later is low), it is preferably 9.5% or more.

In addition, the MgO content may be, for example, 30.0% or less, and is preferably 24.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold, and further reduces the Young's mode with respect to temperature changes. From the viewpoint of quantitative change, it is preferably 22.0% or less, and from the viewpoint of improving the rigidity (eg, Young's modulus) of the glass at the temperature at which the press molding process is usually performed in addition to the above-mentioned aspects, it is preferably 21.0% or less. On the basis of these aspects, from the viewpoint of improving the heat resistance of the glass (for example, the glass transition temperature), it is preferably 20.5% or less. From the viewpoint of low α), it is preferably 20.0% or less.

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

The CaO content may be, for example, 15.0% or less, and is preferably 10.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold and suppressing the reduction of the glass transition temperature. From the viewpoint of the change in Young's modulus with respect to the temperature change, it is preferably 8.0% or less, and in addition to the above-mentioned aspect, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed From the viewpoints, it is preferably 7.0% or less, and in addition to these aspects, from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 6.0% or less. In addition to these aspects, from the viewpoint of improving the glass From the viewpoint of the thermal expansion characteristics (for example, low α described later), it is preferably 5.5% or less.

The SrO content may be 0.0% or more or more than 0.0%. SrO is a component that can contribute to the adjustment of the meltability of glass, and is also a component that can contribute to further reducing the change in Young's modulus with respect to temperature change by substituting with an alkali component.

The SrO content may be, for example, 12.0% or less, and is preferably 6.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold and suppressing the reduction of the Young's modulus of the glass. From the viewpoint of further reducing the change in Young's modulus with respect to temperature change, it is preferably 5.0% or less, and in addition to the above, the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed is improved. ), it is preferably 4.0% or less, and in addition to these aspects, from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 3.5% or less, and on the basis of these aspects, from From the viewpoint of improving the thermal expansion characteristics of the glass (for example, α to be described later is low), the content is preferably 3.0% or less.

The BaO content may be 0.0% or more or more than 0.0%. BaO is a component that can contribute to the adjustment of the meltability of glass, and is also a component that can contribute to further reducing the change in Young's modulus with respect to temperature change by substituting with an alkali component.

The BaO content may be, for example, 12.0% or less, and is preferably 8.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold and suppressing the reduction of the Young's modulus of the glass. From the viewpoint of further reducing the change in Young's modulus with respect to temperature change, it is preferably 5.0% or less, and in addition to the above, the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed is improved. ), it is preferably 4.5% or less, and in addition to these aspects, from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 4.0% or less, and on the basis of these aspects, from From the viewpoint of improving the thermal expansion characteristics of the glass (for example, the below-mentioned α is low), it is preferably 3.8% or less.

The ZnO content may be 0.0% or more or more 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.

The ZnO content may be, for example, 10.0% or less, and is preferably 5.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold and the above-mentioned aspects, and from the viewpoint of further reducing Young's change with respect to temperature change From the viewpoint of a change in modulus, it is preferably 4.0% or less, and from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press-molding process is usually performed in addition to the above-mentioned aspects, it is preferably 3.5% Hereinafter, in addition to these points, from the point of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 3.0% or less, and in addition to these points, in order to improve the thermal expansion characteristics of the glass (for example, to be described later) From the viewpoint of low α), it is preferably 2.5% or less.

The Li ₂ O content may be 0.0% or more or more than 0.0%. Suppressing the Li ₂ O content to a certain amount or less can contribute to further reducing the change in Young's modulus with respect to temperature change, suppressing the decrease in the glass transition temperature, and/or suppressing the decrease in the Young's modulus.

The Li ₂ O content may be, for example, 8.0% or less, and is preferably 3.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold and the above-mentioned aspects. From the viewpoint of the change in Young's modulus, it is preferably 2.0% or less, and from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press-molding process is usually carried out in addition to the above, it is preferably 2.0% or less. 1.5% or less, in addition to these aspects, from the viewpoint of improving the heat resistance (eg glass transition temperature) of the glass, preferably 1.0% or less, on the basis of these aspects, from the viewpoint of improving the thermal expansion characteristics of the glass (eg From the viewpoint of α (low) described later, it is preferably 0.5% or less.

The Na ₂ O content may be 0.0% or more or more than 0.0%. Suppressing the Na ₂ O content to a certain amount or less can contribute to further reducing the change in Young's modulus with respect to the change in temperature, suppressing the decrease in the glass transition temperature, and/or suppressing the decrease in the Young's modulus.

The Na ₂ O content is preferably 3.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature change, and in addition to the above, from the viewpoint of improving the rigidity ( For example, from the viewpoint of Young's modulus), it is preferably 2.0% or less, and in addition to these aspects, from the viewpoint of improving the heat resistance (eg, glass transition temperature) of the glass, it is preferably 1.0% or less. In addition to , from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later), it is preferably 0.5% or less.

The K ₂ O content may be 0.0% or more or more than 0.0%. Suppressing the K ₂ O content to a certain amount or less can contribute to further reducing the change in Young's modulus with respect to temperature change, suppressing the decrease in the glass transition temperature, and/or suppressing the decrease in the Young's modulus.

The content of K ₂ O is preferably 3.0% or less from the viewpoint of further reducing the change in Young's modulus with respect to temperature change, and from the above-mentioned viewpoint, from the viewpoint of improving the rigidity ( For example, from the viewpoint of Young's modulus), it is preferably 2.0% or less, and in addition to these aspects, from the viewpoint of improving the heat resistance (eg, glass transition temperature) of the glass, it is preferably 1.0% or less. In addition to , from the viewpoint of improving the thermal expansion characteristics of the glass (for example, low α described later), it is preferably 0.5% or less.

ZrO ₂ is a component which may be optionally contained in the above-mentioned glass, for example, in order to increase Young's modulus. The ZrO ₂ content may be, for example, 0.0% or more or more than 0.0%. The ZrO ₂ content may be, for example, 10.0% or less, and is preferably 4.0% or less from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass-making mold, and further reduces the Young's modulus with respect to temperature changes. From the viewpoint of change, it is preferably 2.0% or less, and in addition to the above-mentioned aspects, from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press molding process is usually performed, it is preferably 2.0% or less, In addition to these aspects, from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 1.0% or less, and in addition to these aspects, from the viewpoint of improving the thermal expansion characteristics of the glass (for example, α described later) From the viewpoint of low), it is preferably 0.5% or less.

TiO ₂ is a component that may be optionally contained in the above-mentioned glass, for example, in order to increase Young's modulus and/or suppress generation of air bubbles in a glass-making mold. The TiO ₂ content may be, for example, 0.0% or more or more than 0.0%. The TiO ₂ content may be 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold.

In addition, the TiO ₂ content may be, for example, 6.0% or less, and preferably 5.0% or less from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass-making mold, and further reduces Young's change with respect to temperature change. From the viewpoint of a change in modulus, it is preferably 4.0% or less, and from the viewpoint of improving the rigidity (for example, Young's modulus) of the glass at the temperature at which the press-molding process is usually performed in addition to the above-mentioned aspects, it is preferably 3.0% Hereinafter, in addition to these points, from the point of view of improving the heat resistance (for example, glass transition temperature) of the glass, it is preferably 2.0% or less, and in addition to these points, in order to improve the thermal expansion characteristics of the glass (for example, to be described later) From the viewpoint of low α), it is preferably 1.0% or less.

The La ₂ O ₃ content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less, from the viewpoint of reducing the change in Young's modulus with respect to temperature change. _{The La2O3} content may be 0.0%, 0.0% or more, or more than 0.0%.

The content of Y ₂ O ₃ is preferably 4.0% or less, more preferably 3.0% or less, and preferably 2.0% or less, from the viewpoint of reducing the change in Young's modulus with respect to temperature change. The content of Y ₂ O ₃ may be 1.0% or less or 0.5% or less, and may also be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

The Yb ₂ O ₃ content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less, from the viewpoint of reducing the change in Young's modulus with respect to temperature change. The content of Yb ₂ O ₃ may be 1.0% or less or 0.5% or less, and may be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

The Ta ₂ O ₅ content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less, from the viewpoint of reducing the change in Young's modulus with respect to temperature change. The Ta ₂ O ₅ content may be 1.0% or less or 0.5% or less, and may be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

The Nb ₂ O ₅ content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less, from the viewpoint of reducing the change in Young's modulus with temperature change. The Nb ₂ O ₅ content may be 1.0% or less or 0.5% or less, and may also be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

The HfO ₂ content is preferably 4.0% or less, more preferably 3.0% or less, and even more preferably 2.0% or less, from the viewpoint of reducing the change in Young's modulus with respect to temperature change. The HfO ₂ content may be 1.0% or less or 0.5% or less, and may also be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

SnO ₂ is a component that may be optionally contained in the above-mentioned glass, for example, in order to increase Young's modulus and/or suppress generation of air bubbles in a glass-making mold. The SnO ₂ content may be, for example, 0.0% or more or more than 0.0%. The SnO ₂ content may be 0.05% or more, 0.3% or more, or 0.5% or more from the viewpoint of suppressing the generation of air bubbles, striae and/or undissolved matter in the glass forming mold.

In addition, the SnO ₂ content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, from the viewpoint of suppressing the generation of air bubbles, striae and/or undissolved matter in the glass forming mold , preferably 0.5% or less. The SnO ₂ content may be 0.2% or less or 0.1% or less, and may also be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

CeO ₂ is a component that may be optionally contained in the above-mentioned glass, for example, in order to increase Young's modulus and/or suppress generation of air bubbles in a glass-making mold. The CeO ₂ content may be, for example, 0.0% or more or more than 0.0%. The CeO ₂ content may be 0.05% or more, 0.3% or more, or 0.5% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold.

In addition, the CeO ₂ content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold , preferably 0.5% or less. The CeO ₂ content may be 0.2% or less or 0.1% or less, and may also be 0.0% (ie, not contained), 0.0% or more, or more than 0.0%.

Sb ₂ O ₃ is a component optionally contained in the above-mentioned glass, for example, in order to increase Young's modulus and/or suppress generation of air bubbles in a glass-forming mold. The Sb ₂ O ₃ content may be, for example, 0.0% or more or more than 0.0%. The Sb ₂ O ₃ content may be 0.05% or more, 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold.

In addition, the Sb ₂ O ₃ content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0%, from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass-making mold. % or less, preferably 0.5% or less.

Fe ₂ O ₃ is a component that may be optionally contained in the above-mentioned glass, for example, in order to increase Young's modulus and/or suppress generation of air bubbles in a glass-making mold. The Fe ₂ O ₃ content may be, for example, 0.0% or more or more than 0.0%. The Fe ₂ O ₃ content may be 0.05% or more, 0.3% or more, or 0.5% or more from the viewpoint of suppressing the generation of bubbles, striae and/or undissolved matter in the glass forming mold.

In addition, the Fe ₂ O ₃ content is preferably 2.0% or less, preferably 1.0% or less, preferably 0.5% or less, and preferably 0.2% from the viewpoint of suppressing generation of bubbles, striae, and/or undissolved matter in the glass-making mold. % or less, preferably 0.01% or less.

<Glass Properties>

In one embodiment, the glass constituting the above-mentioned glass forming mold can have one or more of the glass physical properties described below.

(glass transition temperature Tg, yield point temperature Ts)

In the present invention and this specification, the glass transition temperature Tg and the yield point temperature Ts of the glass constituting the above-mentioned glass forming mold are values obtained by the following methods.

Cut out a glass sample from a glass forming mold, or make a glass sample made of the same material as the glass forming mold. For each glass sample, thermal expansion characteristics were measured by a method according to JOGIS08-2003. Specifically, the Tg (unit:° C.) of the glass is rounded to the nearest 1 to obtain a temperature on a scale of 10° C., this temperature is set as the annealing temperature, and the glass sample is placed in an annealing temperature that can be raised to this temperature. In the furnace, it takes 1 to 2 hours to raise the temperature from room temperature (about 25°C) to the above-mentioned set temperature, and after holding for 2 hours, the temperature is lowered at a cooling rate of -30°C/hour for 4 hours, and then the temperature is kept at room temperature (about 25°C) in the furnace. ) Natural cooling, the glass sample after natural cooling is processed into a cylindrical glass sample with a diameter of 4.0 mm to 5.0 mm × a length of 10 mm to 20 mm. A load of 98 mN was applied to the glass sample, heated at a temperature increase rate of 4°C/min in this state, the elongation (unit: mm) with respect to the temperature was measured every 1 second, and the obtained graph (so-called thermal expansion curve). The temperature corresponding to the intersection of the extended line of the straight line portion of the low temperature region and the high temperature region in the above graph is taken as the glass transition temperature Tg, and the temperature at which the apparent expansion stops in the above graph, that is, the elongation rate increases with temperature. The temperature at the inflection point from increasing to decreasing is taken as the yield point temperature Ts.

The glass transition temperature Tg of the glass is preferably 755°C or higher, more preferably 760°C or higher, and still more preferably 765°C or higher, so that the glass-forming mold can be a mold suitable for press molding at a higher temperature. , more preferably 770°C or higher. Moreover, the glass transition temperature Tg of the said glass may be 860 degrees C or less, 855 degrees C or less, 850 degrees C or less, 845 degrees C or less, or 840 degrees C or less, for example.

In addition, in order that the above-mentioned glass forming mold can be a forming mold suitable for press molding at a higher temperature, the yield point temperature Ts of the above-mentioned glass is preferably 830°C or higher, more preferably 835°C or higher, and still more preferably 840°C above, and more preferably 845°C or above. Moreover, the yield point temperature Ts of the said glass may be 940 degrees C or less, 935 degrees C or less, 930 degrees C or less, 925 degrees C or less, or 920 degrees C or less, for example.

(average coefficient of linear expansion α)

For example, as shown in FIG. 1, a glass forming mold and a guide mold can be combined to constitute an optical element manufacturing apparatus. It is preferable to adjust the thermal expansion characteristics of the glass constituting the glass forming mold from the viewpoint of controlling the stress received by the glass forming mold in the optical element manufacturing apparatus when combined with the components such as the guide mold. In one embodiment, the thermal expansion characteristic of the glass constituting the above-mentioned glass-making mold is preferably 23.5×10 ⁻⁷ /°C or more, more preferably α in the temperature range of 100°C to 300°C. It is 24.0×10 ^-7 /°C or higher, more preferably 24.5×10 ^-7 /°C or higher, and still more preferably 25.0×10 ^-7 /°C or higher. The average linear expansion coefficient α of the glass is preferably 48.0×10 ^-7 /°C or lower, more preferably 47.0×10 ^-7 /°C or lower, further preferably 46.0×10 ^-7 /°C or lower, and even more preferably 45.0 ×10 ^-7 /°C or lower, more preferably 44.0 × 10 ^-7 /°C or lower.

The above-mentioned average linear expansion coefficient α is calculated by the formula: α=d/(L×T). d is the amount of change in the length of the sample 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 apparatus for the coefficient of linear expansion, a thermomechanical analysis apparatus (TMA; Thermomechanical Analysis) or a dilatometer can be used.

The above-mentioned average linear expansion coefficient α can be obtained, for example, by the following method.

For a glass sample cut out from a glass-making mold, or a glass sample made of the same material as the glass-making mold, a thermomechanical analyzer (TMA; Thermomechanical Analysis) can be used to determine the Tg ( The unit: °C) is rounded up to one digit to obtain a temperature with a scale of 10 °C, this temperature is set as the annealing temperature, and the glass sample is placed in an annealing furnace that can be heated to this temperature, and the temperature is changed from room temperature (about 25 °C) ) for 1 to 2 hours to raise the temperature to the above set temperature, hold for 2 hours, slowly cool at -30°C/hour for 4 hours, then naturally cool to room temperature (about 25°C) in the furnace, and test the glass after natural cooling. The sample was processed into a cylindrical glass sample with a diameter of 4.0 mm to 5.0 mm and a length of 10 mm to 20 mm. This glass sample was subjected to a load of 98 mN, heated at a temperature increase rate of 4°C/min in this state, and the elongation (unit: mm) with respect to the temperature was measured every 1 second. Thermal expansion curve) to obtain the average linear expansion coefficient α.

In one embodiment, the constituent member of the optical element manufacturing apparatus such as a guide mold may be a member made of silicon carbide (SiC). The above-mentioned average linear expansion coefficient α of SiC is about 37×10 ⁻⁷ /°C. When α of the glass constituting the above-mentioned glass-making mold is “A×10 ⁻⁷ /° C.”, from the viewpoint of suppressing the drop of the optical element during the manufacture of the optical element, it is calculated by the formula: X=A-37 X is preferably a negative value. From this point of view, X calculated by the above formula of the glass is preferably -13.5 or more, more preferably -13.0 or more, still more preferably -12.5 or more, and still more preferably -12.0 or more. In addition, the above-mentioned X may be, for example, 11.0 or less, 10.0 or less, 9.0 or less, 8.0 or less, or 7.0 or less, and is preferably less than 0.0 from the above point.

In addition, the absolute value |X| of the above-mentioned X is preferably 13.0 or less, more preferably 12.5 or less, and still more preferably 12.0 or less, from the viewpoint of suppressing stress applied to the glass-made mold from the SiC-made member in the optical element manufacturing apparatus , more preferably 11.5 or less. In addition, the absolute value |X| is preferably 0.0 or more, and more preferably more than 0.0.

(proportion)

It is preferable that the specific gravity of the said glass is small from the point of the adjustment of the specific modulus mentioned later. The specific gravity of the glass is preferably 2.98 or less, more preferably 2.93 or less, still more preferably 2.88 or less, and even more preferably 2.83 or less. Moreover, the specific gravity of the said glass may be 2.35 or more, 2.37 or more, 2.40 or more, or 2.43 or more, for example, and may be lower than the value illustrated here. The specific gravity of the above-mentioned glass can be determined by the Archimedes method with respect to a glass sample for measurement cut out from a glass mold or a glass sample for measurement composed of the same material as the glass mold.

(Young's modulus)

It is preferable that the Young's modulus of the glass which comprises the said glass making mold is high from a viewpoint of suppressing deformation|transformation of the said glass making mold. From this point of view, the Young's modulus of the glass is preferably 87.0 GPa or more, more preferably 88.0 GPa or more, still more preferably 89.0 GPa or more, and even more preferably 90.0 GPa or more. Moreover, the Young's modulus of the said glass may be 101.0GPa or less, 100.0GPa or less, 99.0GPa or less, 98.0GPa or less, or 97.0GPa or less, for example, or may exceed the value illustrated here. The Young's modulus of the above-mentioned glass can be measured at 25°C±5 for a glass sample for measurement cut out from a glass mold or a glass sample for measurement composed of the same material as the glass mold. The measurement temperature in °C is obtained by the ultrasonic pulse method described in JIS R1602:1995. The size of the glass sample for measurement can be appropriately set to a size equal to or greater than the minimum size described in JIS R1602:1995.

(specific modulus)

The specific modulus is obtained by dividing the Young's modulus of the glass by the density. Here, the density can be considered as a value obtained by adding the unit of g/cm ³ to the specific gravity of glass. A molding die made of glass with a higher specific modulus can be said to be a molding die that is lighter in weight but not easily deformed. From this point of view, the specific modulus of the glass is preferably 31.0MNm/kg or more, more preferably 32.0MNm/kg or more, still more preferably 33.0MNm/kg or more, and still more preferably 33.5MNm/kg or more. In addition, the specific modulus of the glass may be, for example, 41.0MNm/kg or less, 40.5MNm/kg or less, 40.0MNm/kg or less, 39.5MNm/kg or less, or 39.0MNm/kg or less, and may exceed the values exemplified here.

(modulus of stiffness)

The rigidity modulus of glass indicates the degree of easiness of deformation against shear force, and it is preferable that the rigidity modulus of the glass constituting the above-mentioned glass forming mold is high from the viewpoint of suppressing deformation of the above-mentioned glass forming mold. From this point of view, the rigidity modulus of the glass may be 33.0 GPa or more, preferably 34.0 GPa or more, 35.0 GPa or more, and 36.0 GPa or more in this order. The rigidity modulus of the said glass may be 42.0GPa or less, 41.5GPa or less, 41.0GPa or less, 40.5GPa or less, or 40.0GPa or less, for example.

The rigidity modulus of the above-mentioned glass can be measured at 25°C±5°C for a glass sample for measurement cut out from a glass mold or a glass sample for measurement composed of the same material as the glass mold. It was obtained by the ultrasonic pulse method described in JIS R1602:1995 at the measurement temperature of . The size of the glass sample for measurement can be appropriately set to a size equal to or greater than the minimum size described in JIS R1602:1995.

(Poisson's ratio)

The Poisson's ratio of glass is a unitless parameter calculated from the ratio of Young's modulus to rigidity modulus. The Poisson's ratio of the glass may be, for example, 0.190 or more, and preferably 0.195 or more, 0.200 or more, 0.205 or more, and 0.210 or more in this order. Moreover, the Poisson's ratio of the said glass may be 0.333 or less, for example, Preferably it is 0.300 or less, 0.290 or less, 0.280 or less, 0.270 or less, and 0.260 or less in this order.

The Poisson's ratio of the above-mentioned glass can be measured at 25°C ± 5°C for a glass sample for measurement cut out from a glass mold or a glass sample for measurement composed of the same material as the glass mold. It was obtained by the ultrasonic pulse method described in JIS R1602:1995 at the measurement temperature of . The size of the glass sample for measurement can be appropriately set to a size equal to or greater than the minimum size described in JISR1602:1995.

(liquidus temperature LT)

Liquidus temperature LT is mentioned as an index of the meltability of glass. The liquidus temperature LT of the glass constituting the glass forming mold is preferably 1440°C or lower, more preferably 1420°C or lower, still more preferably 1400°C or lower, and still more preferably 1380°C or lower, from the viewpoint of improving the meltability of the glass. , more preferably 1360°C or lower. Moreover, the liquidus temperature LT of the said glass may be 1150 degreeC or more, 1170 degreeC or more, 1200 degreeC or more, or 1230 degreeC or more, for example, and may be lower than the value illustrated here.

The "liquidus temperature" in the present invention and the present specification refers to a glass sample for measurement cut out from a glass forming mold or a glass sample for measurement composed of the same material as the glass forming mold by the following method. ask for.

About 20 cc of glass (for example, 50 g for glass with a specific gravity of 2.5 g/cc) is placed in a platinum crucible, and heated in a furnace with an atmosphere temperature of 1400 to 1600 °C for 15 to 30 minutes to bring it into a molten state After that, it is cooled to below the glass transition temperature Tg. After the cooled glass was moved into a furnace at a furnace atmosphere temperature T and held in the furnace for 16 hours, the presence or absence of crystal precipitation was determined by optical microscope observation (100 times magnification).

For different T (10°C scale), the presence or absence of crystal precipitation was determined by the method described above, respectively. The lowest temperature of T at which precipitation of crystals was not confirmed was taken as the liquidus temperature.

[Manufacturing method of glass molding mold]

The above-mentioned glass forming mold can be produced by extruding a glass blank for a glass forming mold using a master mold to obtain a glass forming mold having a concave or convex molding surface.

FIG. 2 is a schematic cross-sectional view of an example of a manufacturing apparatus of a molding die for glass (hereinafter, also referred to as a “molding die manufacturing apparatus”). The molding die manufacturing apparatus of FIG. 2 includes an upper die (mother die) 31 having a convex-shaped molding surface 34 , a lower die 32 , and a guide die 33 . The glass blank 41 is pressed between the upper die 31 and the lower die 32, and the surface shape of the molding surface 34 of the upper die is transferred to the glass blank 41, thereby obtaining a glass molding die having a concave shaped molding surface . The surface shape of the lower mold 32 may be any of a flat shape, a convex shape, and a concave shape, and is not particularly limited. In addition, in the molding die manufacturing apparatus of FIG. 2, the master mold for transferring the surface shape to the glass blank to form the molding surface of the glass molding mold is the upper mold, but the master mold may be arranged as the lower mold mold.

The upper die 31 and the lower die 32 are supported in a guide die (usually also referred to as a "sleeve") 33 so as to be movable relative to each other, and the mutual interval can be changed. Both the upper mold 31 and the lower mold 32 may be movable movable molds, or one may be a movable mold and the other may be a stationary mold that does not move.

A heater (not shown) is provided outside the guide die 33 . At the time of molding, a heater may be used to heat the glass blank 41 to a molding temperature Ta at which the glass blank 41 is softened. Ta may be set according to the kind of glass blank, for example, it can be the range of 700 degreeC - 1000 degreeC, Preferably it is the range of 750 degreeC - 950 degreeC. In addition, in one form, Ta=Ts±50°C. In the molding die manufacturing apparatus of FIG. 2 , 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 .

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

After that, the glass blank 41 is cooled in a state in contact with the surface of the mother mold. Regarding the cooling rate C in this cooling step, in terms of the average cooling rate from Ta to Tb, which will be described later, from the viewpoint of improving the productivity of the glass-making mold and/or suppressing the thermal degradation of the master mold, it 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, and may be -100.0 °C/min or less, -50.0 °C/min or less, -30.0 °C/min or less, -25.0 °C/min or less, -20.0 °C/min or less, -18.0 °C/min or less , -16.0°C/min or less, -14.0°C/min or less, -12.0°C/min or less, -10.0°C/min or less, -5.0°C/min or less, -3.0°C/min or less, or -1.0°C/min or less.

In one form, from the viewpoint of improving productivity, the press load and/or the cooling rate may be switched at a temperature Tm that exceeds Tb and is lower than Ta. The cooling rate C at this time can be expressed as C (unit: °C/min) = (Ta- Tb)/{(Ta-Tm)/Ca+(Tm-Tb)/Cb}.

It is thought that reducing the cooling rate C in the above-mentioned cooling process helps to reduce the change in Young's modulus with respect to the temperature change, and the present inventors speculate that this will lead to a reduction in the value of the Newton's ring change amount A _590°C , which in turn reduces the Newton's ring change Quantity A _590°C value. Therefore, when a glass forming mold is produced from a glass blank having a composition in which the Young's modulus change with temperature change tends to be large, the above-mentioned cooling rate C can be reduced, so that the Newton can be reduced. The value of the ring change amount A _590°C can be further reduced by the value of the Newton ring change amount A _590°C . From this point of view, the 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 surface of the master mold is released. In this way, the glass blank 41 is press-molded, and a glass molding mold having a concave molding surface formed by transferring the surface shape of the master surface (the molding surface 34 of the upper mold 31 in FIG. 2 ) can be obtained. The cancellation|release of the said contact state can be performed at the temperature Tb at which hardening of glass fully progresses. Tb is preferably sufficiently lower than the strain point of glass, and from this point of view, it can be, for example, Tg-150°C or lower, preferably Tg-160°C or lower, more preferably Tg-180°C or lower, and further preferably Tg-200°C or lower. From the viewpoint of making it easy to make the temperature of the glass forming mold and/or master mold 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. In addition, Tb is preferably sufficiently lower than the Tg of the glass-forming mold, and from this point of view, it may 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, and 400°C or lower. , below 350℃ or below 300℃. During the period of cooling from Ta to Tb, the pressing load may be continuously applied to the glass blank 41 by the upper die 31 and/or the lower die 32 as appropriate, or only the load of the die's own weight may be sufficient.

Using the molding die molding apparatus of FIG. 2 , a glass molding die having a concave molding surface was obtained. On the other hand, if the surface shape of the molding surface of the master mold is a concave shape, by transferring the concave shape to the glass blank, a glass molding die having a molding surface having a convex shape can be obtained. One or more of known post-processes such as annealing and coating film formation can be arbitrarily applied to the glass-forming mold taken out from the molding-mold forming apparatus.

The material of the master mold is not particularly limited. From the viewpoints of heat resistance, durability, and the like, a master mold made of silicon carbide (SiC), glass, or the like is preferable. The master mold can be produced by a known method.

[Manufacturing method of optical element]

1 aspect of this invention relates to the manufacturing method of an optical element which comprises press-molding a to-be-molded material with the said glass-made molding die.

As for the manufacturing method of the said optical element, the well-known technique regarding manufacture of the optical element by press molding can be applied, except for the point of using the glass molding die described above. An example of the manufacturing apparatus for optical elements which can be used for press molding is the manufacturing apparatus for optical elements of FIG. 1 demonstrated above.

As the optical element, various lenses such as spherical lenses, aspherical lenses, and microlenses, prisms, and the like can be exemplified. In addition, the material to be molded may be a glass blank, and the optical element may be an optical element made of glass.

For example, a glass block processed into a press molding (hereinafter, referred to as "glass blank for press molding") can be press-molded using the above-mentioned glass-forming mold. Examples of glass blanks for press molding include preforms for precision press molding, glass blanks for obtaining optical element blanks by press molding (glass gobs for press molding), and the like, which have a quality comparable to a press-molded product. quality glass blocks. The glass blank for press molding is produced through the process of processing a glass molding. A glass molded body can be manufactured by heating and melting a glass raw material, and shape|molding the obtained molten glass. As a processing method of a glass molding, cutting, grinding, grinding, etc. can be illustrated. In addition, the optical element blank is a glass molding having a shape similar to that of the optical element to be manufactured. The optical element blank can be produced by a method or the like in which glass is formed into a shape obtained by superimposing the amount of processing removed by processing in addition to the shape of the optical element to be produced. For example, a method of heating and softening a glass material for press molding and press-molding (reheat press method), or a method of supplying a molten glass block to a press-molding mold by a known method and press-molding (direct press method) etc. to make optical element blanks.

For example, the shape accuracy of the molding surface of a molding die for precision press molding is desired to be several times the shape accuracy required for optical elements. According to the manufacturing method of the glass-made molding die described above, the surface shape of a master mold can be transferred with high precision, and the glass-made molding die can be manufactured. The thus obtained glass molding mold is suitable as a molding mold for precision press molding. However, since the excellent shape accuracy of the molding surface is preferable in various press moldings, the glass molding mold produced by the above-mentioned production method is not limited to the molding mold for precision press molding, and is suitable for various press molding. Use a forming mold.

Hereinafter, a specific example of a method of obtaining an optical element made of glass by press molding will be described.

The molding surface of the glass-made mold was covered with a carbon film as a release film, and was placed in the optical element manufacturing apparatus. After supplying the glass blank for press molding (the glass blank to be shaped) into the optical element manufacturing apparatus, it is heated to a temperature at which the viscosity of the glass blank to be shaped reaches a viscosity equivalent to 10 ⁸ dPa·s to 10 ¹² dPa·s. After softening, the molding surface of the glass molding mold is transferred to the glass blank to be molded by pressing it with a molding die. The set temperature of the apparatus at this time is called a press temperature. In addition, in order to prevent oxidation of a molding surface, it is preferable to make the atmosphere at the time of molding non-oxidizing. After that, an appropriate load application program (for example, -50°C/min, etc.) can be applied to the glass forming mold and the glass blank to be shaped, and the molding surface can be kept in close contact with the glass blank to be shaped, while cooling until the In the vicinity of the glass transition temperature of the glass of the glass blank to be molded, the optical element manufacturing apparatus is opened (decomposed), and the molded body (optical element) is taken out.

Example

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

[Examples 1 to 5, Comparative Example A]

<Glass blanks for glass molds>

Glass blanks having the glass compositions shown in Table 1 were prepared by the following method.

Various oxides, boric acid, carbonate, and sulfate were used as raw materials for introducing each component so that the glass composition shown in Table 1 was obtained, and the raw materials were weighed and mixed well to prepare a preparation raw material. At this time, a total of 200 g of raw materials in terms of oxides were used. The crucible containing the prepared raw materials is put into a glass melting furnace, and the glass is melted, clarified and homogenized at 1600°C for 3 hours, and the molten glass is poured from the crucible into a preheated mold for molding. Next, the shaped glass was taken out from the mold, put into an annealing furnace whose furnace temperature was set to 750°C, and annealed at an annealing cooling rate of -30°C/hour to obtain a glass blank.

[Table 1-1]

Table 1

[Table 1-2]

<Master mold>

A SiC-made master mold is prepared as a master mold.

<Preparation of glass molding mold by press molding>

Each glass blank was press-molded by the method described above using the molding die manufacturing apparatus having the structure shown in FIG. 2 . The temperature Ta was set to the temperature shown in Table 2, and the glass blank was pressed with a load in a state in which it was in contact with the surface of the mother mold. The temperature Tb was set to the temperature shown in Table 1, and the average cooling from the temperature Ta to Tb was carried out. Cooling was performed at the cooling rate shown in Table 2 at the rate C. In any 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-mentioned cooling, it is naturally cooled to about room temperature in the molding die forming apparatus, the contact state with the master mold is released, and the surface shape of the master mold is taken out from the molding die manufacturing apparatus. forming mold.

In this way, a glass molding die having a concave molding surface was produced.

[Table 2]

Table 2

[Evaluation of glass molding molds]

<Glass Properties>

With respect to each of the glass forming molds of Examples 1 to 5 and Comparative Example A, various glass physical properties shown in Table 3 were obtained by the methods exemplified above, and are shown in Table 3.

[table 3]

table 3

<Newton's ring change A _590°C , Newton's ring change A _650°C , Newton's ring change rate with respect to temperature>

For each of the glass forming molds of Examples 1 to 5 and Comparative Example A, the amount of Newton's ring change A _590°C , the amount of Newton's ring change A _650°C , and the change in Newton's ring change with respect to temperature were obtained by the methods described above. rate, shown in Table 4. As the shape measuring device, a three-dimensional measuring machine (UA3P manufactured by Panasonic Production Engineering) was used.

[Manufacture and Evaluation of Optical Components]

It is considered that when the optical element is mass-produced by press molding, the less the shape change of the molding surface of the glass-made mold is, the more it is possible to suppress the occurrence of the shape deviation of the optical element. The degree of change in the shape of the molding surface of the glass molding mold when mass-producing optical elements by press molding can be evaluated by the following method.

The glass molding mold is exposed to the environment of the molding temperature in one lens molding cycle, and after being heated, it is cooled to the vicinity of the glass transition temperature. It is considered that the shape change of the molding surface of the glass-making mold mainly occurs at the high molding temperature in one lens molding cycle, and the change increases as the number of molding times increases. According to the method described above, Newton's rings are calculated from the shape of the glass mold used for lens molding for a certain number of times (number of shots) X or more (for example, 50 shots or more) at a certain molding temperature and the shape before use number of bars. As the shape measuring device, a three-dimensional measuring machine (UA3P manufactured by Panasonic Production Engineering) was used. Divide the difference D between the number of Newton rings before and after use (after use - before use) by the number of injections X, and multiply the value D/X by 100 times as the amount of Newton's ring change ΔN per injection. , and the amount of Newton's ring change 100D/X per 100 injections was obtained. The lower limit of the value of the number of press times X for obtaining 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 until the shape change of the glass-forming mold does not occur, the apparent ΔN will decrease, which may not be suitable for evaluation. Therefore, the upper limit of X is preferably 100 or less, and more preferably 80 or less. , more preferably 60 or less.

For example, regarding the amount of Newton's ring change ΔN per shot at 590°C, the shape and use of a glass-made mold that can be used for lens molding by a certain number of times X (50≤X≤100) at a molding temperature of 590°C The number of Newton rings calculated by the method described above is calculated, and the value D obtained by dividing the difference D (after use - before use) of the number of Newton rings before and after lens molding and use by the number of shots X is calculated. /X was used as "change amount ΔN of Newton's ring per injection at 590°C". It can be estimated that the smaller the value thus obtained, the less the shape change of the molding surface of the glass-forming mold is when mass-producing optical elements by press molding.

For Examples 1 to 5 and Comparative Example A, the above-mentioned concave-shaped glass molds were used as the upper mold and the lower mold, respectively, and the optical element having the structure shown in FIG. 1 was used by the method of the specific example described above. In the production apparatus, the molding temperature was set to 590° C. and the number of shots was set to X (50≦X≦60), and precision press molding of the glass to be formed glass blank was repeated to produce a glass optical element (lenticular lens). Then, 100D/X, which is obtained by multiplying ΔN=D/X obtained by the above method by 100 times, is calculated as "the amount of change in Newton's ring per injection at 590°C ΔN is multiplied by 100 times. The value of " is shown in Table 4. The "value obtained by multiplying the amount of Newton's ring change ΔN per injection at 590°C by 100 times" may be 0.00 or more or more than 0.00, and preferably 1.00 or less, more preferably 0.90 or less, and 0.80 in that order. or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, 0.30 or less. In Comparative Example A, since the change in the shape of the molding surface of the molding die was large, and it was not possible to perform press molding up to the number of shots X, it was shown in Table 4 as "impossible to press."

[Table 4]

Table 4

Finally, the above methods are summarized.

According to one aspect, there is provided a glass-made mold for molding an optical element, the amount of Newton's ring change A _590°C before and after annealing at a temperature of 590°C is 0.00 or more and 1.50 or less.

According to the above-described glass forming mold, when the optical element is mass-produced by press molding, it is possible to suppress the occurrence of shape deviation of the optical element.

In one form, the amount of Newton's ring change A _650°C before and after annealing at a temperature of 650°C in the glass-forming mold may be 0.00 or more and 1.50 or less.

In one embodiment, in the above-mentioned glass forming mold, in the temperature range of 590°C to 650°C, the rate of change of the amount of Newton's ring change with respect to temperature may be 0.00×10 ^-2 bars/°C or more and 4.00×10 ^-2 bars /°C or less.

In one embodiment, in the above-mentioned glass forming mold, in the temperature range of 590°C to 650°C, the rate of change of the amount of Newton's ring change with respect to temperature may be 0.00×10 ^-2 bars/°C or more and 2.50×10 ^-2 bar/°C or less.

In one embodiment, the total content of SiO ₂ and Al ₂ O ₃ may be 60.0% or more in the glass composition represented by the mol % of the glass.

In one embodiment, in the glass composition represented by the mol % of the glass, the content of SiO ₂ may be 51.0% to 79.0%, the content of Al ₂ O ₃ may be 8.0% to 24.0%, and the content of MgO, CaO, SrO and BaO may be 51.0% to 79.0%. The total content may be 1.0% to 35.0%.

In one embodiment, the glass may be aluminosilicate glass, and in the glass composition represented by the mol % of the glass, the content of MgO may be 1.0% to 30.0%, the content of CaO may be 0.0 to 15.0%, and the content of SrO may be 0.0～12.0%, BaO content can be 0.0～12.0%, ZnO content can be 0.0～10.0%, Li ₂ O content can be 0.0～8.0%, total content of Na ₂ O and K ₂ O can be 0.0～4.25% , the ZrO ₂ content can be 0.0-10.0%, the TiO ₂ content can be 0.0-6.0%, and 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 of can be 0.0 to 4.0%.

In one embodiment, in the glass composition represented by the mol % of the glass, the molar ratio of the total content of Li ₂ O, Na ₂ O and K ₂ O to the total content of SiO ₂ , Al ₂ O ₃ and MgO (Li ₂ O+Na ₂ O+K ₂ O)/(SiO ₂ +Al ₂ O ₃ +MgO) may be in the range of 0.000 to 0.050.

According to one aspect, there is provided a method of manufacturing a glass-made molding die, which is the above-mentioned manufacturing method of a glass-made molding die, comprising: extruding a glass blank for molding a molding die in contact with a surface of a master mold pressing; and cooling the glass blank for forming the molding die in the abutting state, and the cooling rate in the cooling is −30.0° C./min or less.

In one embodiment, the cooling rate in the cooling may be -15.0°C/min or less.

According to one aspect, there is provided a method of manufacturing an optical element, which includes press-molding a material to be molded using the above-described glass-made mold.

In one form, the optical element described above may be an optical element made of glass.

It should be understood that the embodiments disclosed this time are illustrative and non-restrictive in all respects. The scope of the present invention is shown not by the above description but by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

For example, it is needless to say that any combination of two or more of the aspects illustrated in the specification or described as preferred ranges is possible.

Claims (12)

1. A glass-made molding die for molding an optical element, wherein the amount of Newton's ring change A590°C before and after annealing at a temperature of _590°C is 0.00 or more and 1.50 or less. 2 . The glass forming mold according to claim 1 , wherein the Newton ring change amount A _{650° C.} before and after annealing at a temperature of 650° C. is 0.00 or more and 1.50 or less. 3 . 3. The glass forming mold according to claim 1 or 2, wherein in the temperature range of 590°C to 650°C, the rate of change of the amount of Newton's ring change with respect to temperature is 0.00×10 ⁻² bars/°C or more 4.00×10 ^-2 bars/°C or less. 4 . The glass forming mold according to claim 1 , wherein, in a temperature range of 590° C. to 650° C., the rate of change of the amount of Newton’s ring change with respect to temperature is 0.00×10 ⁻² . 2.50×10 ^-2 bars/°C or less. 5 . The glass forming mold according to claim 1 , wherein, in the glass composition represented by the mol % of the glass, 5 . The total content of SiO ₂ and Al ₂ O ₃ is 60.0% or more. 6 . The glass forming mold according to claim 1 , wherein, in the glass composition represented by the mol % of the glass, 6 . The content of SiO ₂ is 51.0% to 79.0%, The Al ₂ O ₃ content is 8.0% to 24.0%, and, The total content of MgO, CaO, SrO and BaO is 1.0% to 35.0%. 7. The glass forming mold according to any one of claims 1 to 6, wherein The glass is aluminosilicate glass, In the glass composition expressed in mol % of the glass, The MgO content is 1.0% to 30.0%, The CaO content is 0.0 to 15.0%, The SrO content is 0.0 to 12.0%, BaO content is 0.0 to 12.0%, ZnO content is 0.0 to 10.0%, Li ₂ O content is 0.0-8.0%, The total content of Na ₂ O and K ₂ O is 0.0-4.25%, The content of ZrO ₂ is 0.0 to 10.0%, The TiO ₂ content is 0.0 to 6.0%, and, The total content of La ₂ O ₃ , Y ₂ O ₃ , Yb ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ and HfO ₂ is 0.0 to 4.0%. 8 . The glass forming mold according to claim 1 , wherein, in the glass composition represented by the mol % of the glass, 8 . Molar ratio of the total content of Li ₂ O, Na ₂ O, K ₂ O to the total content of SiO ₂ , Al ₂ O ₃ and MgO (Li ₂ O+Na ₂ O+K ₂ O)/(SiO ₂ +Al ₂ O ₃ +MgO) is in the range of 0.000 to 0.050. 9 . A method for manufacturing a molding mold made of glass, which is the method for manufacturing a molding mold made of glass according to any one of claims 1 to 8 , comprising: extruding in a state where the glass blank for forming the forming die is brought into abutment with the surface of the mother die; and cooling the glass blank for forming the forming mold in the abutting state, The cooling rate in the cooling is -30.0°C/min or less. 10 . The method for producing a glass-forming mold according to claim 9 , wherein the cooling rate in the cooling is −15.0° C./min or less. 11 . 11 . A method for producing an optical element, comprising press-molding a to-be-molded material using the glass-made mold according to claim 1 . 12. The method of manufacturing an optical element according to claim 11, wherein the optical element is an optical element made of glass.

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