CN114751641A

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

Info

Publication number: CN114751641A
Application number: CN202210012503.5A
Authority: CN
Inventors: 仓泽裕己; 佐藤浩一; 白石幸一郎
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2021-01-08
Filing date: 2022-01-06
Publication date: 2022-07-15
Anticipated expiration: 2042-01-06
Also published as: JP2022107530A

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 molding die for molding optical element, method for manufacturing glass molding die, and method for manufacturing optical element

Technical Field

The present invention relates to 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.

Background

As a method for manufacturing an optical element such as a lens, a method of press molding a material to be molded with a molding die is widely used. As a mold usable in this manufacturing method, patent document 1 discloses a glass mold.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2019-127425

Disclosure of Invention

Problems to be solved by the invention

When mass production of optical elements is performed by press molding a material to be molded with a molding die, it is common to repeat press molding of a plurality of materials to be molded with one molding die. From the viewpoint of stably supplying optical elements having desired optical properties to the market, it is preferable that the shape variations of the optical elements mass-produced in this way are small.

An object of one embodiment of the present invention is to provide a glass-made molding die that can suppress the occurrence of shape variations in optical elements when the optical elements are mass-produced by press molding.

Means for solving the problems

One embodiment of the present invention relates to a glass forming mold (hereinafter, also simply referred to as "glass forming mold" or "forming mold") for forming an optical element, the change a of newton ring before and after annealing at a temperature of 590 ℃_590℃The number of the strands is 0.00 to 1.50.

The inventors have conducted intensive studies repeatedly, and as a result, have newly found that: in order to suppress the occurrence of the shape variation of the optical element, a glass molding die having a small change in shape before and after a cooling process usually included in a press molding step of the optical element should be used. And, the above-mentioned A _590℃Can be used as an index of the shape change by using A_590℃The glass forming mold with 0-1.5 strips can be used for compression molding of multiple materials to be molded, and mass production of optical elements with less shape deviation can be realizedAnd (3) a component.

ADVANTAGEOUS EFFECTS OF INVENTION

According to one aspect of the present invention, there is provided a glass-made molding die capable of suppressing occurrence of shape variations in optical elements when the optical elements are mass-produced by press molding. Further, according to an aspect of the present invention, it is possible to provide a method for manufacturing a glass molding die suitable for manufacturing the glass molding die and a method for manufacturing an optical element using the glass molding die.

Drawings

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

Fig. 2 is a schematic cross-sectional view showing an example of a manufacturing apparatus for a glass molding die.

Detailed Description

[ glass-made Molding die for Molding optical element ]

The glass molding die will be described in more detail below. The following description is sometimes made with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

< construction of glass Molding die >

Fig. 1 is a schematic cross-sectional view of an example of an optical element manufacturing apparatus provided with a glass molding die. The optical element manufacturing apparatus 10 of fig. 1 is a manufacturing apparatus for manufacturing an optical element 20 from a material 21 to be molded by press molding, and includes an upper mold 11 and a lower mold 12 as a glass molding die. The upper die 11 and the lower die 12 are supported in the guide die 13 so as to be relatively movable, and the interval therebetween can be changed. The upper mold 11 and the lower mold 12 may be both movable molds, or one may be a movable mold and the other may be a fixed mold.

The glass molding die may be an upper die 11 in one embodiment and a lower die 12 in another embodiment. In another embodiment, the change amount A of Newton's rings before and after annealing at 590 ℃ may be set for the upper mold 11 and the lower mold 12_590℃0.00 to 1.50 glass piecesAnd (5) molding. The glass constituting the upper mold 11 and the lower mold 12 may be the same glass in one embodiment, and may be different glasses in another embodiment. In a preferred embodiment, the change amount A of Newton's rings before and after annealing at 590 ℃ may be set for both the upper mold 11 and the lower mold 12 _590℃The number of the glass-forming dies is 0.00 to 1.50, and in a more preferable embodiment, the glass constituting the upper die 11 and the lower die 12 may be the same glass.

The upper die 11 and the lower die 12 have a molding surface 14 and a molding surface 15 on the sides facing each other. The optical element 20 is specifically a biconvex lens having aspheric surfaces on both sides, and the molding surface 14 and the molding surface 15 are concave surfaces (aspheric surfaces) having shapes corresponding to the respective convex surfaces (aspheric surfaces) of the optical element 20. That is, the shapes of the molding surface 14 and the molding surface 15 are transferred by press molding, and the convex surface of the optical element 20 is formed. However, the embodiment shown in fig. 1 is merely an example, and the molding surface of the glass molding die has a convex shape in one aspect and a concave shape in another aspect.

The

molding surfaces

14 and 15 are respectively provided with films 16 and 17. The coatings 16 and 17 may be generally called release films, for example, carbon films, and can suppress the sticking of the material to be molded. The coatings 16 and 17 shown in fig. 1 have a single-layer structure, but a multilayer structure having different compositions may be provided. Alternatively, the

molding surfaces

14 and 15 may be exposed without providing the films 16 and 17.

A heater (not shown) is provided outside the guide die 13. At the time of molding, the molding material may be heated by a heater to a molding temperature at which the molding material 21 is softened.

In the present invention and the present specification, the "glass molding die" 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 except for the coating films 16 and 17 may be made of glass. Alternatively, only a portion of the upper mold 11 and the lower mold 12 including the molding surface 14 and the molding surface 15 may be made of glass, and a base portion made of another material such as metal may be joined to the glass portion to form the upper mold 11 and the lower mold 12.

<Newton's ringVariation A_590℃>

Change A of Newton's Ring before and after annealing at 590 deg.C in the above glass-forming mold_590℃The number of the strands is 0.00 to 1.50.

Newton's Ring variation A_590℃The measurement was carried out by the following method.

The shape of the molded surface of the glass mold before annealing was measured at room temperature (about 25 ℃ C.) by using a shape measuring device. Examples of the shape measuring device include an interferometer and a three-dimensional measuring machine (for example, UA3P manufactured by Panasonic Production Engineering). The number of Newton rings was calculated from the value of the radius of curvature R of the molded surface (paraxial R in the case of the molded surface having an aspherical surface) measured by the shape measurement so that the measurement wavelength was 546.1 nm.

Then, the glass-made mold was placed in an annealing furnace, the temperature in the furnace was raised from room temperature (about 25 ℃) to a holding temperature of 590 ℃ for 5 hours, the temperature was held at 590 ℃ for 4 hours, then the temperature was lowered to a holding temperature of-100 ℃ at a cooling rate of-50 ℃/hour for 2 hours, and then the glass-made mold was cooled to room temperature (about 25 ℃) by cooling with power off.

The number of Newton rings was calculated for the annealed glass mold taken out of the annealing furnace so that the measurement wavelength was 546.1 nm.

The difference in the number of Newton rings between before and after annealing (after annealing-before annealing) was defined as A_590℃。

Further, the Newton's Ring variation A will be described in detail later_650℃The annealing was carried out in the following manner, and the annealing temperature was determined by the method described above.

The temperature in the annealing furnace was raised from room temperature (about 25 ℃ C.) to a holding temperature of 650 ℃ for 5 hours, and after holding at 650 ℃ C. for 4 hours, the temperature was lowered to the holding temperature of-100 ℃ at a cooling rate of-50 ℃ C/hour for 2 hours, and thereafter, the annealing furnace was cooled to room temperature (about 25 ℃ C.) by cooling with power off.

The present inventors considered that the above-mentioned change A in Newton's Ring_590℃Is a glass forming mold capable of being used as a cooling step usually included in a press molding process of an optical element The index value of the shape change is likely to occur. More specifically, the inventors considered that the above-mentioned change amount A of Newton's rings_590℃The glass-made mold having a diameter of 0.00 to 1.50 strands is less likely to change in shape before and after a cooling process normally included in a press molding step of an optical element, and according to this mold, it is possible to suppress the occurrence of shape variations of the optical element when the optical element is mass-produced by press molding. The amount of change in Newton's Ring of the glass-made mold is set so that the variation in shape of the optical element can be further suppressed_590℃Preferably 1.00 or less, more preferably 0.50 or less, and still more preferably 0.25 or less. Further, the amount of change of Newton's Ring A_590℃The number of the strands is 0.00 or more, for example, 0.01 or more. Among them, the newton ring change amount a is preferable from the viewpoint of suppressing the occurrence of shape variations in the optical element_590℃Is small, so that the Newton's Ring variation A is small_590℃Also below 0.01 stripes.

<Newton's Ring variation A_650℃>

In one embodiment, the glass-forming mold may have a change amount a of newton ring before and after annealing at a temperature of 650 ℃_650℃The number of the glass forming molds is 0.00 to 1.50. The inventors considered that the Newton's Ring variation A _590℃In the above-mentioned range and the Newton's Ring variation A_650℃When the number of the molding dies is 0 or more and 1.50 or less, the shape change before and after the cooling process usually included in the molding step of the optical element is less, and according to such a molding die, the occurrence of shape variations in the optical element can be further suppressed when the optical element is mass-produced by molding. The amount of change in Newton's Ring of the glass-made mold is set so that the variation in shape of the optical element can be further suppressed_650℃Preferably 1.50 or less, and more preferably 1.00 or less, 0.50 or less, and 0.25 or less, in this order. Further, the amount of change of Newton's Ring A_650℃For example, the number of the strands may be 0.00 or more or 0.05 or more. The change amount A of Newton's rings is preferably selected from the viewpoint of suppressing the occurrence of shape variations in the optical element_650℃Is small, so that the Newton's Ring variation A is small_650℃Also less than 0.05 strips.

< Change Rate of Newton Ring Change amount with respect to temperature >

In one embodiment, the glass-forming mold may have a rate of change of newton ring change amount with respect to temperature of 0.00 × 10 in a temperature range of 590 to 650 ℃^-24.00 x 10 at above bar/DEG C^-2A glass molding die having a bar/DEG C or lower. In order to further suppress the occurrence of shape variations in the optical element when the optical element is mass-produced by press molding, the change rate of the newton ring change amount with respect to temperature is preferably small. From the above aspect, in the above glass-made molding die, the rate of change of the amount of change of Newton's Ring with respect to temperature is preferably 4.00X 10 in the temperature range of 590 to 650 DEG C ^-2bar/DEG C or less, more preferably 3.50X 10^-2The strip/DEG C is preferably 3.00X 10 or less^-2bar/DEG C or less, more preferably 2.50X 10^-2The ratio of the length of the strip to the temperature of less than 2.00X 10 is more preferable in this order^-2Strip/° C or less, 1.50 × 10^-2strip/DEG C or less, 1.00X 10^-2Bars/° c. Further, the glass forming mold may have a rate of change of the amount of change of newton ring with respect to temperature of 0.00 × 10^-2bar/DEG C or higher, or may be 0.05X 10^-2bars/deg.C or higher. However, since the rate of change of the amount of change in newton ring with respect to temperature is preferably small in order to suppress the occurrence of shape variations in the optical element, the rate of change of the amount of change in newton ring with respect to temperature may be less than 0.05 × 10^-2bar/deg.C.

The change rate of the newton ring change amount with respect to temperature is determined by the following method.

The amount of change A in Newton's Ring of the glass mold was determined by the method described above_590℃And Newton's Ring Change amount A_650℃. From the determined A_590℃And A_650℃The rate of change (unit: bar/. degree. C.) of the above change in Newton's rings was determined by the following equation.

The change rate of the newton ring change amount is (a)_650℃－A_590℃)/(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 is as described later.

The glass constituting the glass-made mold will be described in more detail below.

< glass composition >

In the present invention and the present specification, the glass composition is expressed by the cationic component of the glass on an oxide basis. Here, the "oxide-based glass composition" refers to a glass composition obtained by converting glass raw materials into oxides that are present in the glass as they are all decomposed during melting. Unless otherwise specified, the glass composition is expressed on a molar basis (mol%, molar ratio).

The content of the element (mass% of the element) contained in the glass can be quantified by a known method, for example, inductively coupled plasma emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), or the like. The content of each element (mass% of the element) can be determined by dividing the content by the atomic weight.

In the present invention and the present specification, the content of the constituent component being 0% or not contained or not introduced means that the constituent component is not substantially contained, and the constituent component is allowed to be contained at an inevitable impurity level.

In one embodiment, the glass may be an aluminosilicate glass. In the present invention and the present specification, "aluminosilicate glass" means a glass containing at least SiO as a cation component of the glass in a glass composition expressed on an oxide basis₂And Al₂O₃The glass of (2).

Of the above glasses, SiO₂With Al₂O₃Total content of (SiO)₂+Al₂O₃) For example, 60.0% or more is preferable. The inventors believe that the total content (SiO)₂+Al₂O₃) 60.0% or more contributes to reducing the change in Young's modulus with respect to the change in temperature, which results inReduction of Newton's Ring variation A_590℃Is measured, thereby reducing the Newton's Ring variation A_590℃The value of (c). From this aspect, the total content (SiO)₂+Al₂O₃) Preferably 65.0% or more, and preferably 66.0% or more in terms of enhancing the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and preferably 68.0% or more in terms of enhancing the heat resistance (e.g., glass transition temperature) of the glass in addition to the above-described aspect, and preferably 70.0% or more in terms of improving the thermal expansion characteristics (e.g., low α described later) of the glass in addition to the above-described aspect.

On the other hand, total content (SiO)₂+Al₂O₃) For example, it may be 100.0% or less, and preferably 91.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and preferably 90.5% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, and preferably 90.5% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and preferably 89.5% or less from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

Li₂O、Na₂O and K₂Molar ratio of total O content to MgO content ((Li)₂O+Na₂O+K₂O)/MgO) may be, for example, 0.000 or more than 0.000. Molar ratio ((Li)₂O+Na₂O+K₂O)/MgO) may be, for example, 0.400 or less, and preferably 0.300 or less from the viewpoint of further reducing the change in young's modulus with respect to a change in temperature, and preferably 0.200 or less from the viewpoint of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is normally performed, and preferably 0.150 or less from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, and from the viewpoint of improving the glassFrom the viewpoint of thermal expansion characteristics (e.g., a is low as described later), it is preferably 0.100 or less.

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 a change in temperature, and is preferably 0.550 or more from the viewpoint of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is normally performed, and is preferably 0.600 or more from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, and is preferably 0.650 or more from the viewpoint of improving the thermal expansion characteristics (for example, low α described later) of the glass.

Li₂O+Na₂O+K₂Total content of O (Li)₂O+Na₂O+K₂O) may be, for example, 0.0% or more than 0.0%. In addition, total content (Li)₂O+Na₂O+K₂O) may be, for example, 4.25% or less. Total content (Li) from the viewpoint of further reducing the change in Young's modulus with respect to the change in temperature₂O+Na₂O+K₂O) is preferably 4.0% or less, and in addition to the above, 3.0% or less is preferable from the viewpoint of enhancing the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and in addition to these, 2.0% or less is preferable from the viewpoint of enhancing the heat resistance (e.g., glass transition temperature) of the glass, and in addition to these, 1.0% or less is preferable from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

Na₂O and K₂Total content of O (Na)₂O+K₂O) may be, for example, 0.0% or more than 0.0%. In addition, the total content (Na)₂O+K₂O) may be, for example, 4.25% or less. The total content (Na) is determined from the viewpoint of further reducing the change in Young's modulus with respect to the change in temperature or from the viewpoint of not excessively increasing the thermal expansion coefficient₂O+K₂O) may be, for example, 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, or 0.5% or less.

The total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) may be 35.0% or less, for example. 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 a change in temperature, and is preferably 30.0% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and is preferably 27.5% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and is preferably 25.0% or less from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

The total content (MgO + CaO + SrO + BaO) may be 0.0% or more or 1.0% or more, for example. The total content (MgO + CaO + SrO + BaO) is preferably 8.0% or more in terms of further reducing the change in young's modulus with respect to a change in temperature, and is preferably 8.5% or more in terms of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is normally performed, and is preferably 9.0% or more in terms of improving the heat resistance (for example, glass transition temperature) of the glass in addition to these, and is preferably 9.5% or more in terms of improving the thermal expansion characteristics (for example, low α described later) of the glass in addition to these.

The total content of MgO and CaO (MgO + CaO) may be 32.5% or less, for example. 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 a temperature change, and is preferably 27.5% or less from the viewpoint of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is generally performed, and is preferably 25.0% or less from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, and is preferably 22.5% or less from the viewpoint of improving the thermal expansion characteristics (for example, low α described later) of the glass.

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 in terms of further reducing the change in young's modulus with respect to a temperature change, and is preferably 8.5% or more in terms of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is normally performed, and is preferably 9.0% or more in terms of improving the heat resistance (for example, glass transition temperature) of the glass in terms of these aspects, and is preferably 9.5% or more in terms of improving the thermal expansion characteristics (for example, low α described later) of the glass in terms of these aspects.

SiO₂、Al₂O₃And total content of MgO (SiO)₂+Al₂O₃+ MgO) may be, for example, 100.0% or less than 100.0%. In addition, the total content (SiO)₂+Al₂O₃+ MgO) may be 80.0% or more, for example. Total content (SiO) in order to further reduce the change in Young's modulus with respect to the change in temperature₂+Al₂O₃+ MgO) is preferably 85.0% or more, and in addition to the above, is preferably 86.0% or more in terms of improving the rigidity (for example, young's modulus) of the glass at the temperature at which the press molding step is normally performed, and in addition to these, is preferably 87.0% or more in terms of improving the heat resistance (for example, glass transition temperature) of the glass, and in addition to these, is preferably 88.0% or more in terms of improving the thermal expansion characteristics (for example, low α described later) of the glass.

Li₂O、Na₂O、K₂O, SrO and BaO (Li)₂O+Na₂O+K₂O + SrO + BaO) may be, for example, 0.0% or more than 0.0%.

In addition, the total content (Li)₂O+Na₂O+K₂O + SrO + BaO) may be, for example, 4.5% or less, and preferably 3.5% or less from the viewpoint of further reducing the change in young's modulus with respect to a change in temperature, and in addition to the above, from the viewpoint of improving the degree of improvement in the molding process in generalThe rigidity (e.g., young's modulus) of the glass at temperature is preferably 3.0% or less, and in addition to these, the rigidity is preferably 2.0% or less in order to improve the heat resistance (e.g., glass transition temperature) of the glass, and in addition to these, the rigidity is preferably 1.0% or less in order to improve the thermal expansion characteristics (e.g., a low α described later) of the glass.

SiO₂、Al₂O₃、MgO、CaO、ZrO₂And TiO₂Total content of (SiO)₂+Al₂O₃+MgO+CaO+ZrO₂+TiO₂) For example, it may be 100.0% or less than 100.0%. In addition, the total content (SiO)₂+Al₂O₃+MgO+CaO+ZrO₂+TiO₂) For example, it may be 85.0% or more, preferably 90.0% or more from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and in addition to the above, 91.0% or more from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and in addition to these, 92.0% or more from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and in addition to these, 93.0% or more from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

Li₂O、Na₂O and K₂Molar ratio of total content of O to total content of MgO and CaO ((Li)₂O+Na₂O+K₂O)/(MgO + CaO)) may be, for example, 0.000 or more than 0.000. In addition, the molar ratio ((Li)₂O+Na₂O+K₂O)/(MgO + CaO)) may be, for example, 2.000 or less, preferably 0.150 or less from the viewpoint of further reducing the change in young's modulus with respect to a change in temperature, preferably 0.100 or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, preferably 0.050 or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass,from the viewpoint of improving the thermal expansion characteristics of the glass (for example, a is low as described later), it is preferably 0.030 or less.

Li₂O+Na₂O+K₂Total content of O relative to SiO₂+Al₂O₃+ molar ratio of total content of MgO ((Li)₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃+ MgO)) may be, for example, 0.000 or more than 0.000. In addition, the molar ratio ((Li)₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃+ MgO)) may be, for example, 0.050 or less, and preferably 0.040 or less from the viewpoint of further reducing the change in young's modulus with respect to a change in temperature, and in addition to the above, 0.030 or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding process is normally performed, and 0.020 or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and in addition to these, 0.010 or less from the viewpoint of improving the thermal expansion characteristics (e.g., a low described later) of the glass.

Li₂O+Na₂O+K₂The total content of O + SrO + BaO relative to SiO₂+Al₂O₃+MgO+CaO+ZrO₂+TiO₂Molar ratio of the total content of ((Li)₂O+Na₂O+K₂O+SrO+BaO)/(SiO₂+Al₂O₃+MgO+CaO+ZrO₂+TiO₂) ) may be 0.000 or more than 0.000. In addition, the molar ratio ((Li)₂O+Na₂O+K₂O+SrO+BaO)/(SiO₂+Al₂O₃+MgO+CaO+ZrO₂+TiO₂) For example, 0.100 or less, preferably 0.090 or less from the viewpoint of further reducing the change in young's modulus with respect to a change in temperature, and preferably 0.080 or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and preferably 0.06 or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass0 or less, and in addition to these, 0.050 or less is preferable in terms of improving the thermal expansion characteristics of the glass (for example, α is low as described later).

La₂O₃、Y₂O₃、Yb₂O₃、Ta₂O₅、Nb₂O₅And HfO₂Total content of (La)₂O₃+Y₂O₃+Yb₂O₃+Ta₂O₅+Nb₂O₅+HfO₂) May be 0.000% or more than 0.000%. In addition, the total content (La)₂O₃+Y₂O₃+Yb₂O₃+Ta₂O₅+Nb₂O₅+HfO₂) For example, the Young's modulus may be 5.0% or less, and from the viewpoint of further reducing the change in Young's modulus with respect to a change in temperature or not excessively reducing the specific modulus, 4.0% or less, 3.0% or less, 2.0% or less, and 1.0% or less are preferable in this order.

SiO₂Is a glass skeleton component and is a component useful for reducing the change in Young's modulus with respect to a change in temperature. SiO is used for suppressing generation of bubbles, striae and/or undissolved matter in a glass mold ₂The content is preferably 51.0% or more, and is preferably 55.0% or more from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and is preferably 56.0% or more from the viewpoint of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is usually performed, and is preferably 57.0% or more from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, and is preferably 58.0% or more from the viewpoint of improving the thermal expansion characteristics (for example, low α described later) of the glass.

In addition, SiO is used for suppressing the generation of bubbles, striae, and/or undissolved matter in the glass mold₂The content is preferably 79.0% or less, and from the viewpoint of further reducing the change in Young's modulus with respect to a change in temperature, is preferably 76.0% or less, in the above formulaIn addition, the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is normally performed is preferably 75.0% or less, in addition, the heat resistance (for example, glass transition temperature) of the glass is preferably 74.0% or less, and in addition, the thermal expansion characteristic (for example, low α described later) of the glass is preferably 73.0% or less.

Al₂O₃Is a glass skeleton component and is a component useful for reducing the change in Young's modulus with respect to a change in temperature. Al for suppressing generation of bubbles, striae, and/or undissolved matter in a glass mold₂O₃The content is preferably 8.0% or more, and is preferably 10.0% or more from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and is preferably 11.0% or more from the viewpoint of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is usually performed, and is preferably 12.0% or more from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, and is preferably 12.5% or more from the viewpoint of improving the thermal expansion characteristics (for example, low α described later) of the glass.

Further, Al is added to suppress the generation of bubbles, striae, and/or undissolved matter in the glass mold₂O₃The content is preferably 24.0% or less, and is preferably 22.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and is preferably 21.0% or less from the viewpoint of improving the rigidity (for example, young's modulus) of the glass at a temperature at which the press molding step is generally performed, and is preferably 20.5% or less from the viewpoint of improving the heat resistance (for example, glass transition temperature) of the glass, and is preferably 20.0% or less from the viewpoint of improving the thermal expansion characteristics (for example, a is low, which will be described later) of the glass.

B₂O₃Is, for example, adjustedViscosity of the glass and may optionally contain ingredients in the above glass. B₂O₃The content may be, for example, 0.0% or more than 0.0%, and 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, from the viewpoint of further reducing the change in Young's modulus with respect to the change in temperature, B₂O₃The content is preferably 2.0% or less, and in addition to the above, 2.0% or less is also preferable from the viewpoint of enhancing the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, and in addition to these, 2.0% or less is also preferable from the viewpoint of enhancing the heat resistance (e.g., glass transition temperature) of the glass, and in addition to these, 2.0% or less is also preferable from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

MgO is a component that contributes to an increase in young's modulus, a decrease in specific gravity (and an increase in specific modulus due to a decrease in specific gravity) and/or a decrease in α described below of the glass. The MgO content may be 0.0% or more, more than 0.0% or 1.0% or more, and is preferably 6.0% or more from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass forming mold, and is preferably 8.0% or more from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and is preferably 8.5% or more from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and is preferably 9.0% or more from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and is preferably 9.5% or more from the viewpoint of improving the thermal expansion characteristics (e.g., a low described later) of the glass.

The MgO content may be, for example, 30.0% or less, preferably 24.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass mold, preferably 22.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, preferably 21.0% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, preferably 20.5% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and preferably 20.0% or less from the viewpoint of improving the thermal expansion characteristics (e.g., a low α described later) of the glass.

The CaO content may be 0.0% or more than 0.0%. CaO is a component that contributes to an increase in Young's modulus and a decrease in specific gravity of glass (and an increase in specific modulus due to a decrease in specific gravity), and is preferably used in combination with MgO.

The CaO content may be, for example, 15.0% or less, preferably 10.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass mold and suppressing the decrease in glass transition temperature, more preferably 8.0% or less from the viewpoint of further reducing the change in young's modulus with respect to the temperature change, preferably 7.0% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, preferably 6.0% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and preferably 5.5% or less from the viewpoint of improving the thermal expansion characteristics (e.g., a low described later) of the glass.

The SrO content may be 0.0% or more than 0.0%. SrO is a component that can contribute to adjustment of the melting property of glass, and also contributes to further reduction of the change in young's modulus with respect to a temperature change by substitution with an alkali component.

The SrO content may be, for example, 12.0% or less, preferably 6.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass-forming mold and suppressing the decrease in the young's modulus of the glass, more preferably 5.0% or less from the viewpoint of further decreasing the change in the young's modulus with respect to a temperature change, and preferably 4.0% or less from the viewpoint of increasing the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, and preferably 3.5% or less from the viewpoint of increasing the heat resistance (e.g., glass transition temperature) of the glass, and preferably 3.0% or less from the viewpoint of improving the thermal expansion characteristics (e.g., a is low, which will be described later) of the glass.

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

The BaO content may be, for example, 12.0% or less, preferably 8.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass-made mold and suppressing the decrease in the young's modulus of the glass, more preferably 5.0% or less from the viewpoint of further decreasing the change in the young's modulus with respect to a temperature change, preferably 4.5% or less from the viewpoint of increasing the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, preferably 4.0% or less from the viewpoint of increasing the heat resistance (e.g., glass transition temperature) of the glass, and preferably 3.8% or less from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

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

The ZnO content may be, for example, 10.0% or less, preferably 5.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass mold and the above-mentioned viewpoint, preferably 4.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, preferably 3.5% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, preferably 3.0% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass and preferably 2.5% or less from the viewpoint of improving the thermal expansion characteristics (e.g., a low described later) of the glass.

Li₂The O content may be 0.0% or more than 0.0%. Mixing Li₂Suppressing the O content to a certain amount or less can contribute to further reducing the change in young's modulus with respect to a temperature change, suppressing a decrease in glass transition temperature, and/or suppressing a decrease in young's modulus.

Li₂The O content may be, for example, 8.0% or less, preferably 3.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass mold and the above-mentioned viewpoint, and preferably 2.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and preferably 1.5% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, and preferably 1.0% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass and preferably 0.5% or less from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass in addition to the above-mentioned aspects.

Na₂The O content may be 0.0% or more than 0.0%. Na is mixed with₂Suppressing the O content to a certain amount or less can contribute to further reducing the change in young's modulus with respect to a temperature change, suppressing a decrease in glass transition temperature, and/or suppressing a decrease in young's modulus.

From the viewpoint of further reducing the change in Young's modulus with respect to the change in temperature, Na₂The O content is preferably 3.0% or less, and in addition to the above, 2.0% or less is preferred in terms of improving the rigidity (e.g., Young's modulus) of the glass at a temperature at which the press molding step is normally performed, and in addition to these, the heat resistance (e.g., glass transition temperature) of the glass is improvedPreferably 1.0% or less, and in addition to these, preferably 0.5% or less in view of improving the thermal expansion characteristics of the glass (for example, a is low as described later).

K₂The O content may be 0.0% or more than 0.0%. Will K₂Suppressing the O content to a certain amount or less can contribute to further reducing the change in young's modulus with respect to a change in temperature, suppressing a decrease in glass transition temperature, and/or suppressing a decrease in young's modulus.

From the viewpoint of further reducing the change in Young's modulus with respect to the change in temperature, K₂The O content is preferably 3.0% or less, and in addition to the above, 2.0% or less is preferable from the viewpoint of enhancing the rigidity (e.g., young's modulus) of the glass at a temperature at which the press molding step is normally performed, and in addition to these, 1.0% or less is preferable from the viewpoint of enhancing the heat resistance (e.g., glass transition temperature) of the glass, and in addition to these, 0.5% or less is preferable from the viewpoint of improving the thermal expansion characteristics (e.g., low α described later) of the glass.

ZrO₂Is a component which may be optionally contained in the above glass, for example, for the purpose of improving the Young's modulus. ZrO (zirconium oxide)₂The content may be, for example, 0.0% or more than 0.0%. ZrO (ZrO)₂The content may be, for example, 10.0% or less, preferably 4.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass mold, and preferably 2.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and preferably 2.0% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, and preferably 1.0% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and preferably 0.5% or less from the viewpoint of improving the thermal expansion characteristics (e.g., a low described later) of the glass.

TiO₂For example, the Young's modulus may be increased and/or bubbles may be suppressed from being generated in a glass moldOptionally containing ingredients in the above glasses. TiO 2₂The content may be, for example, 0.0% or more than 0.0%. TiO in order to suppress the generation of bubbles, striae, and/or undissolved matter in a glass mold ₂The content may be 0.1% or more, 0.3% or more, 0.5% or more, or 1.0% or more.

In addition, TiO₂The content may be, for example, 6.0% or less, preferably 5.0% or less from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in a glass mold, more preferably 4.0% or less from the viewpoint of further reducing the change in young's modulus with respect to a temperature change, and preferably 3.0% or less from the viewpoint of improving the rigidity (e.g., young's modulus) of the glass at a temperature at which a press molding step is normally performed, and preferably 2.0% or less from the viewpoint of improving the heat resistance (e.g., glass transition temperature) of the glass, and preferably 1.0% or less from the viewpoint of improving the thermal expansion characteristics (e.g., a low described later) of the glass.

La is considered to reduce the change in Young's modulus with respect to the change in temperature₂O₃The content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. La₂O₃The content may be 0.0%, 0.0% or more, or more than 0.0%.

From the viewpoint of reducing the change in Young's modulus with respect to the change in temperature, Y ₂O₃The content is preferably 4.0% or less, more preferably 3.0% or less, and preferably 2.0% or less. Y is₂O₃The content may be 1.0% or less or 0.5% or less, or may be 0.0% (that is, not contained), 0.0% or more, or more than 0.0%.

Yb in view of reducing the change in Young's modulus with respect to the change in temperature₂O₃The content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. Yb of₂O₃The content may be 1.0% or less or 0.5% or less, or may be 0.0% (that is, not contained), 0.0% or more than 0.0%。

Ta from the viewpoint of reducing the change in Young's modulus with respect to temperature change₂O₅The content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. Ta₂O₅The content may be 1.0% or less or 0.5% or less, or may be 0.0% (that is, not included), 0.0% or more, or more than 0.0%.

Nb for reducing the change in Young's modulus with respect to the change in temperature₂O₅The content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. Nb₂O₅The content may be 1.0% or less or 0.5% or less, or may be 0.0% (that is, not included), 0.0% or more, or more than 0.0%.

HfO for reducing the change of Young's modulus with respect to the change of temperature₂The content is preferably 4.0% or less, more preferably 3.0% or less, and further preferably 2.0% or less. HfO₂The content may be 1.0% or less or 0.5% or less, or may be 0.0% (that is, not included), 0.0% or more, or more than 0.0%.

SnO₂Are components which may optionally be contained in the above glass, for example, for the purpose of improving the Young's modulus and/or suppressing the generation of bubbles in a glass-made mold. SnO₂The content may be, for example, 0.0% or more than 0.0%. SnO in order to suppress the generation of bubbles, striae and/or undissolved matter in a glass-made mold₂The content may be 0.05% or more, 0.3% or more, or 0.5% or more.

Further, SnO is considered to suppress the generation of bubbles, striae and/or undissolved substances in a glass mold₂The content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, preferably 0.5% or less. SnO₂The content may be 0.2% or less or 0.1% or less, or may be 0.0% (that is, not included), 0.0% or more, or more than 0.0%.

CeO₂For example, for improving Young's modulus and/or suppressing the generation of bubbles in a glass molding die May optionally contain ingredients in the above glasses. CeO (CeO)₂The content may be, for example, 0.0% or more than 0.0%. CeO for suppressing generation of bubbles, striae and/or undissolved matter in a glass mold₂The content may be 0.05% or more, 0.3% or more, or 0.5% or more.

Further, CeO is used for suppressing the generation of bubbles, striae and/or undissolved matter in a glass mold₂The content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, preferably 0.5% or less. CeO (CeO)₂The content may be 0.2% or less or 0.1% or less, or may be 0.0% (that is, not included), 0.0% or more, or more than 0.0%.

Sb₂O₃Are components which may optionally be contained in the above glass, for example, for the purpose of improving the Young's modulus and/or suppressing the generation of bubbles in a glass-made mold. Sb₂O₃The content may be, for example, 0.0% or more than 0.0%. Sb is a compound which suppresses the generation of bubbles, striae and/or undissolved matter in a glass mold₂O₃The content can be more than 0.05%, more than 0.1%, more than 0.3%, more than 0.5% or more than 1.0%.

In addition, Sb is added to suppress the generation of bubbles, striae and/or undissolved matter in the glass mold ₂O₃The content is preferably 3.0% or less, preferably 2.0% or less, preferably 1.5% or less, preferably 1.0% or less, preferably 0.5% or less.

Fe₂O₃Are components which may optionally be contained in the above glass, for example, for the purpose of improving the Young's modulus and/or suppressing the generation of bubbles in a glass-made mold. Fe₂O₃The content may be, for example, 0.0% or more than 0.0%. Fe for suppressing generation of bubbles, striae and/or undissolved matter in a glass mold₂O₃The content may be 0.05% or more, 0.3% or more, or 0.5% or more.

Further, from the viewpoint of suppressing the generation of bubbles, striae, and/or undissolved matter in the glass mold, Fe₂O₃The content is preferably 2.0% or less, preferably 1.0% or less, preferably 0.5% or less, preferably 0.2% or less, preferably 0.01% or less.

< glass Properties >

In one embodiment, the glass constituting the glass molding die may have one or more of the following glass properties.

(glass transition temperature Tg, sag temperature Ts)

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

A glass sample is cut out from the glass forming mold, or a glass sample made of the same material as the glass forming mold is produced. For each glass sample, the thermal expansion characteristics were measured by the method according to JOGIS 08-2003. Specifically, a glass sample is placed in an annealing furnace capable of being heated to a temperature of 10 ℃ on a scale obtained by dividing the Tg (unit:. degree. C.) into two places by three places, and the temperature is set to the annealing temperature, and the glass sample is heated to the temperature from room temperature (about 25 ℃ C.) over 1 to 2 hours, and after being held for 2 hours, the temperature is lowered at a cooling rate of-30 ℃/hour for 4 hours, and then the glass sample is naturally cooled in the furnace at room temperature (about 25 ℃ C.), and the glass sample after natural cooling is processed into a cylindrical glass sample having a diameter of 4.0mm to 5.0mm and a length of 10mm to 20 mm. The glass sample was heated at a temperature rise rate of 4 ℃/min under a load of 98mN, and the elongation (unit: mm) per 1 second with respect to the temperature was measured, and the obtained graph (so-called thermal expansion curve) was prepared. The temperature corresponding to the intersection point of the extensions of the straight line portions of the low temperature region and the high temperature region in the graph is defined as the glass transition temperature Tg, and the temperature at the inflection point where the apparent expansion stops, that is, the elongation changes from increasing to decreasing with an increase in temperature in the graph is defined as the yield point temperature Ts.

In order that the glass-forming mold may be a molding mold suitable for press molding at a higher temperature, the glass transition temperature Tg of the glass is preferably 755 ℃ or higher, more preferably 760 ℃ or higher, still more preferably 765 ℃ or higher, and yet more preferably 770 ℃ or higher. The glass transition temperature Tg of the glass may be, for example, 860 ℃ or lower, 855 ℃ or lower, 850 ℃ or lower, 845 ℃ or lower, or 840 ℃ or lower.

In order that the glass-forming mold may be a mold suitable for press molding at a higher temperature, the sag temperature Ts of the glass is preferably 830 ℃ or higher, more preferably 835 ℃ or higher, still more preferably 840 ℃ or higher, and yet more preferably 845 ℃ or higher. The sag temperature Ts of the glass may be 940 ℃ or lower, 935 ℃ or lower, 930 ℃ or lower, 925 ℃ or lower, or 920 ℃ or lower, for example.

(average coefficient of linear expansion. alpha.)

For example, as shown in fig. 1, a glass molding die and a guide die may be combined to constitute a manufacturing apparatus for an optical element. In order to control the stress to which the glass forming mold is subjected in the optical element manufacturing apparatus when combined with the constituent members such as the guide mold, it is preferable to adjust the thermal expansion characteristics of the glass constituting the glass forming mold. In one embodiment, the thermal expansion characteristic of the glass constituting the glass forming mold is preferably 23.5 × 10 in terms of an average linear expansion coefficient α in a temperature range of 100 to 300 ℃ ^-7/. degree.C.or more, more preferably 24.0X 10^-7/. degree.C.or more, more preferably 24.5X 10^-7/. degree.C.or more, more preferably 25.0X 10^-7Above/° c. In addition, the average linear expansion coefficient α of the glass is preferably 48.0 × 10^-7Lower than/° C, more preferably 47.0X 10^-7Preferably 46.0X 10 or less/° C^-7Lower than/° C, more preferably 45.0X 10^-7Preferably 44.0X 10 or less/° C^-7Below/° c.

The average linear expansion coefficient α is represented by the formula: α is calculated as d/(L × T). d is the amount of change (mm) in the sample length in the temperature range of 100 ℃ to 300 ℃, L is the initial length (mm) of the sample, and T is the temperature difference (K) (300 ℃ to 100 ℃ to 200 ℃). As a device for measuring the linear expansion coefficient, a Thermomechanical analyzer (TMA) or a dilatometer can be used.

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

A glass sample cut out from a glass mold or a glass sample made of the same material as the glass mold is subjected to a Thermal Mechanical Analysis (TMA) in which 1-position of Tg (unit:. degree. C.) of glass is divided into three by 1-position to obtain a temperature of 10 ℃ scale, the temperature is set as an annealing temperature, the glass sample is placed in an annealing furnace capable of being heated up to the annealing temperature, the temperature is raised from room temperature (about 25 ℃) to the above-mentioned set temperature for 1 to 2 hours, the glass sample is held for 2 hours, then slowly cooled for 4 hours at-30 ℃/hour, and then naturally cooled in the furnace to room temperature (about 25 ℃) to process the naturally cooled glass sample into a cylindrical glass sample having a diameter of 4.0mm to 5.0mm and a length of 10mm to 20 mm. The glass sample was heated at a temperature rise rate of 4 ℃/min under a load of 98mN, and the elongation (unit: mm) per 1 second with respect to the temperature was measured, and the average linear expansion coefficient α was determined from the obtained graph (so-called thermal expansion curve).

In one embodiment, the component of the manufacturing apparatus for an optical element such as a guide die may be a silicon carbide (SiC) component. The average linear expansion coefficient α of SiC was 37X 10^-7About/° c. The glass constituting the above glass forming mold has an α of "Ax 10^-7In the case of/° c ", from the viewpoint of suppressing the falling of the optical element during the production of the optical element, the following formula: x calculated by X-a-37 is preferably a negative value. From this viewpoint, X of the glass calculated by the above formula is preferably-13.5 or more, more preferably-13.0 or more, further preferably-12.5 or more, and still more preferably-12.0 or more. In addition, 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 in view of the above.

In the optical element manufacturing apparatus, the absolute value | X | of X is preferably 13.0 or less, more preferably 12.5 or less, further preferably 12.0 or less, and further preferably 11.5 or less, in order to suppress stress on the glass mold from the SiC member. The absolute value | X | is preferably 0.0 or more, and more preferably greater than 0.0.

(specific gravity)

From the aspect of specific modulus adjustment described later, the specific gravity of the glass is preferably small. The specific gravity of the glass is preferably 2.98 or less, more preferably 2.93 or less, further preferably 2.88 or less, and further preferably 2.83 or less. The specific gravity of the glass may be, for example, 2.35 or more, 2.37 or more, 2.40 or more, or 2.43 or more, or may be lower than the values exemplified herein. The specific gravity of the glass can be determined by the archimedes method for a glass sample for measurement cut out from a glass forming mold or for a glass sample for measurement made of the same material as the glass forming mold.

(Young's modulus)

In order to suppress deformation of the glass forming mold, the young's modulus of the glass constituting the glass forming mold is preferably high. From this point of view, the Young's modulus of the glass is preferably 87.0GPa or more, more preferably 88.0GPa or more, still more preferably 89.0GPa or more, and still more preferably 90.0GPa or more. The Young's modulus of the glass may be, for example, 101.0GPa or less, 100.0GPa or less, 99.0GPa or less, 98.0GPa or less, or 97.0GPa or less, or may exceed the values exemplified herein. The Young's modulus of the glass may be determined by cutting a glass sample for measurement out of a glass forming mold or by measuring a glass sample made of the same material as the glass forming mold at a measurement temperature of 25 ℃. + -. 5 ℃ according to JIS R1602: 1995, ultrasonic pulse method. The size of the glass sample for measurement can be appropriately set to JIS R1602: the size above the lowest size reported in 1995.

(specific modulus)

The specific modulus is obtained by dividing the Young's modulus of glass by the density. Here, the density is considered to be the specific gravity added g/cm to the glass³The value obtained in this unit. A mold made of glass having a higher specific modulus can be said to be a mold that is lighter in weight but is less likely to deform. From this aspect, the above glass The specific modulus of the glass is preferably 31.0MNm/kg or more, more preferably 32.0MNm/kg or more, further preferably 33.0MNm/kg or more, and still more preferably 33.5MNm/kg or more. 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, or may exceed the values exemplified herein.

(modulus of rigidity)

The modulus of rigidity of glass indicates the ease of deformation against shear force, and the modulus of rigidity of glass constituting the glass molding die is preferably high in order to suppress deformation of the glass molding die. From this point of view, the glass may have a modulus of rigidity of 33.0GPa or more, preferably 34.0GPa or more, 35.0GPa or more, and 36.0GPa or more in this order. The glass may have a modulus of rigidity of 42.0GPa or less, 41.5GPa or less, 41.0GPa or less, 40.5GPa or less, or 40.0GPa or less, for example.

The modulus of rigidity of the glass can be determined by cutting a glass sample for measurement out of a glass forming mold or by measuring a glass sample made of the same material as the glass forming mold at a measurement temperature of 25 ℃. + -. 5 ℃ according to JIS R1602: 1995, ultrasonic pulse method. The size of the glass sample for measurement may be appropriately set to JIS R1602: the size above the lowest size reported in 1995.

(Poisson's ratio)

The poisson's ratio of glass is a unitless parameter determined from the ratio of young's modulus to stiffness modulus. The poisson ratio of the glass may be, for example, 0.190 or more, and is preferably 0.195 or more, 0.200 or more, 0.205 or more, and 0.210 or more in this order. The poisson ratio of the glass may be 0.333 or less, and is preferably 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 glass can be determined by measuring the poisson's ratio of a glass sample cut out from a glass forming mold or a glass sample made of the same material as the glass forming mold at a measurement temperature of 25 ℃ ± 5 ℃ according to JIS R1602: 1995 (1995) ultrasonic pulse method. The size of the glass sample for measurement can be appropriately set to JIS R1602: the size above the lowest size reported in 1995.

(liquidus temperature LT)

The index of the meltability of the glass includes a liquidus temperature LT. The liquidus temperature LT of the glass constituting the glass forming mold is preferably 1440 ℃ or lower, more preferably 1420 ℃ or lower, still more preferably 1400 ℃ or lower, still more preferably 1380 ℃ or lower, and still more preferably 1360 ℃ or lower, from the viewpoint of improving the meltability of the glass. The liquidus temperature LT of the glass may be, for example, 1150 ℃ or higher, 1170 ℃ or higher, 1200 ℃ or higher, or 1230 ℃ or higher, or may be lower than the values exemplified herein.

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

About 20cc of glass (for example, 50g for a glass having a specific gravity of 2.5 g/cc) is put in a platinum crucible, heated in a furnace at an atmospheric temperature of 1400 to 1600 ℃ for 15 to 30 minutes to be in a molten state, and then cooled to a glass transition temperature Tg or lower. The cooled glass was moved into a furnace at a furnace atmosphere temperature T and held in the furnace for 16 hours, and then observed by an optical microscope (magnification: 100 times) to determine whether or not crystal deposition occurred.

The presence or absence of crystal precipitation was judged for each T (10 ℃ scale) by the method described above. The lowest temperature of T at which crystal precipitation was not observed was defined as the liquid phase temperature.

[ method for producing glass Molding die ]

The glass forming mold can be manufactured by press-molding a glass material for a glass forming mold using a master mold to form a glass forming mold having a concave or convex forming surface.

Fig. 2 is a schematic cross-sectional view of an example of a glass molding die manufacturing apparatus (hereinafter, also referred to as "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 material 41 is pressed between the upper mold 31 and the lower mold 32, and the surface shape of the molding surface 34 of the upper mold is transferred to the glass material 41, thereby obtaining a glass molding die having a concave molding surface. The surface shape of the lower die 32 may be any of a planar shape, a convex shape, and a concave shape, and is not particularly limited. In the mold manufacturing apparatus of fig. 2, the master mold for forming the molding surface of the glass mold by transferring the surface shape to the glass material is the upper mold, but the master mold may be arranged as the lower mold.

The upper die 31 and the lower die 32 are relatively movably supported in a guide die (also referred to as a "sleeve") 33, and the distance between them can be changed. The upper die 31 and the lower die 32 may be both movable dies, or one may be a movable die and the other may be a fixed die.

A heater (not shown) is provided outside the guide die 33. At the time of molding, the glass blank 41 may be heated by a heater to a molding temperature Ta at which the glass blank is softened. Ta may be set according to the kind of the glass material, and may be, for example, in the range of 700 to 1000 ℃ and preferably in the range of 750 to 950 ℃. In one embodiment, Ta may be made equal to Ts ± 50 ℃. 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 material by the heater provided outside the guide die 33.

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

Thereafter, the glass material 41 is cooled in a state of being in contact with the surface of the mother die. The cooling rate C in the cooling step may be-0.1 ℃/min or more, -0.3 ℃/min or more, -0.5 ℃/min or more, -1.0 ℃/min or more, -3.0 ℃/min or more, -5.0 ℃/min or more, -10.0 ℃/min or more, or-15.0 ℃/min or more, or-100.0 ℃/min or less, -50.0 ℃/min or less, -30.0 ℃/min or less, -25.0 ℃/min or less, -20.0 ℃/min or less, -18.0 ℃/min or less, from the viewpoint of improving the productivity of the glass molding die and/or suppressing the thermal degradation of the mother die, based on the average cooling rate from Ta to Tb described later, -16.0 ℃/min or less, -14.0 ℃/min or less, -12.0 ℃/min or less, -10.0 ℃/min or less, -5.0 ℃/min or less, -3.0 ℃/min or less-1.0 ℃/min or less.

In one mode, from the viewpoint of improving productivity, the molding load and/or the cooling rate may be switched at a temperature Tm exceeding Tb and lower than Ta. The cooling rate C in this case can be determined from the cooling rates Ca (unit:. degree. C/min) of Ta to Tm and the cooling rates Cb (unit:. degree. C/min) of Tm to Tb by the ratio of C (unit:. degree. C/min) (Ta-Tb)/{ (Ta-Tm)/Ca + (Tm-Tb)/Cb }.

It is considered that lowering the cooling rate C in the cooling step contributes to lowering the change in Young's modulus with respect to the change in temperature, and the present inventors speculate that this leads to lowering the change amount A of Newton's Ring_590℃And further decrease the Newton's Ring variation A_590℃The value of (c). Therefore, when a glass forming mold is manufactured from a glass material having a composition in which the change in young's modulus with respect to the change in temperature tends to be large as a glass composition, the amount of change in newton ring a can be reduced by lowering the cooling rate C_590℃And further the Newton's Ring variation A can be reduced_590℃The value of (c). From this viewpoint, the cooling rate C is preferably-15 ℃/min or less, more preferably-10 ℃/min or less. After the cooling, the contact state with the surface of the master model is released. Thus, the glass material 41 is press-molded to obtain a glass molding die having a concave molding surface formed by transferring the surface shape of the surface of the master die (the molding surface 34 of the upper die 31 in fig. 2). The above-described release of the contact state may be performed at a temperature Tb at which the curing of the glass is sufficiently performed. Tb is preferably sufficiently lower than the strain point of the glass, and from this viewpoint, it may be, for example, Tg-150 ℃ or lower, preferably Tg-160 ℃ or lower, more preferably Tg-180 ℃ or lower, and still more preferably Tg-200 ℃ or lower. To facilitate the shaping of the glass into moulds and/or In terms of the temperature of the master mold following the cooling rate, Tb may be, for example, 20 ℃ or more, 50 ℃ or more, 70 ℃ or more, 100 ℃ or more, 150 ℃ or more, 200 ℃ or more, 250 ℃ or more, 300 ℃ or more, 350 ℃ or more, or 400 ℃ or more. In addition, Tb is preferably sufficiently lower than Tg of the glass mold, and from this viewpoint, it may be 900 ℃ or lower, 800 ℃ or lower, 700 ℃ or lower, 600 ℃ or lower, 550 ℃ or lower, 500 ℃ or lower, 400 ℃ or lower, 350 ℃ or lower, or 300 ℃ or lower, for example. During the cooling from Ta to Tb, the pressing load may be continuously applied to the glass material 41 by the upper mold 31 and/or the lower mold 32 as appropriate, or may be a load of only the self weight of the mold.

A glass molding die having a concave molding surface was obtained by the molding die molding device of fig. 2. On the other hand, when the surface shape of the molding surface of the master mold is a concave shape, the concave shape is transferred to the glass material, whereby a glass molding die having a convex molding surface can be obtained. One or more of known post-steps such as annealing and film formation may be optionally applied to the glass-made mold taken out of the molding-mold forming device.

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

[ method for producing optical element ]

One embodiment of the present invention relates to a method for manufacturing an optical element, including press molding a material to be molded with the glass mold.

As for the method for producing the optical element, a known technique relating to the production of an optical element by press molding can be applied, except that the above-described glass forming mold is used. An example of the manufacturing apparatus for an optical element that can be used for press molding is the manufacturing apparatus for an optical element illustrated in fig. 1 described above.

Examples of the optical element include various lenses such as a spherical lens, an aspherical lens, and a microlens, and a prism. The material to be molded may be a glass material, and the optical element may be a glass optical element.

For example, a glass gob for press molding (hereinafter referred to as "glass material for press molding") can be press molded using the above-mentioned glass molding die. Examples of the glass material for press molding include glass gobs having a quality equivalent to that of press moldings, such as preforms for precision press molding and glass materials (press molding glass gobs) for obtaining optical element blanks by press molding. The press molding glass material is produced through a step of processing a glass molded body. The glass molded body can be produced by heating and melting a glass raw material and molding the obtained molten glass. Examples of the method of processing the glass molded body include cutting, grinding, and polishing. The optical element blank is a glass molded body having a shape similar to the shape of the optical element to be manufactured. The optical element blank may be produced by a method of molding glass into a shape obtained by superimposing the amount of processing removed by processing on the shape of the optical element to be produced. For example, an optical element blank can be produced by a method in which a glass material for press molding is heated, softened and press molded (reheat press method), a method in which a molten glass gob is supplied to a press mold by a known method and press molded (direct press method), or the like.

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

Specific examples of a method for obtaining a glass optical element by press molding will be described below.

A carbon film is coated on a molding surface of a glass molding die as a mold release film, and is disposed in a manufacturing apparatus for an optical element. A glass material for press molding (a glass material to be molded) is supplied into a manufacturing apparatus for an optical element, and then heated until the viscosity of the glass material to be molded reaches 10⁸dPa·s～10¹²And a temperature corresponding to dPas, and pressing the glass blank with a molding die, thereby transferring the molding surface of the glass molding die to the glass blank to be molded. The set temperature of the apparatus at this time is referred to as a mold temperature. In order to prevent oxidation of the molding surface, the atmosphere during molding is preferably non-oxidizing. Thereafter, the glass forming mold and the glass material to be formed are subjected to an appropriate load application program (for example, -50 ℃/min) and cooled to a temperature near the glass transition temperature of the glass constituting the glass material to be formed while maintaining the adhesion between the forming surface and the glass material to be formed, and thereafter, the manufacturing apparatus for an optical element is opened (disassembled) to take out the formed body (optical element).

Examples

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

Examples 1 to 5 and comparative example A

< glass material for glass forming mold >

Glass blanks having glass compositions shown in table 1 were prepared by the following methods.

Various oxides, boric acid, carbonates, and sulfates were used as raw materials for introducing the respective components so as to achieve the glass compositions shown in table 1, and the raw materials were weighed and sufficiently mixed to prepare formulated raw materials. In this case, 200g of the total amount of the raw materials in terms of oxides were used. The crucible containing the prepared raw materials is put into a glass melting furnace, the glass is melted, clarified and homogenized after being used for 3 hours at 1600 ℃, and the molten glass is poured into a preheated mold from the crucible for molding. Next, the molded glass was taken out of the mold, placed in an annealing furnace having a furnace temperature of 750 ℃ and annealed at an annealing cooling rate of-30 ℃/hr to obtain a glass material.

[ Table 1-1]

TABLE 1

[ tables 1-2]

< mother mold >

A SiC master mold was prepared as a master mold.

< production of glass Molding die by Press Molding >

Each glass material was press-molded by the method described above using a mold manufacturing apparatus having the structure shown in fig. 2. The temperature Ta was set to the temperature shown in table 2, and the glass material was pressed with a load applied in a state in which the surface of the mother die was in contact with the glass material, while the temperature Tb was set to the temperature shown in table 1, and the average cooling rate C between the temperatures Ta to Tb was set to the cooling rate shown in table 2. In each of examples 1 to 5 and comparative example A, the cooling rate Ca between Ta and Tm was set to 10 ℃/min.

After the cooling, the glass-made mold having the molding surface formed by transferring the surface shape of the master mold is removed from the molding-mold manufacturing apparatus after naturally cooling to room temperature in the molding-mold molding apparatus.

Thus, a glass molding die having a concave molding surface was produced.

[ Table 2]

TABLE 2

[ evaluation of glass Molding die ]

< glass Properties >

The physical properties of each glass shown in table 3 were obtained by the above-described exemplary method for each glass-forming mold of examples 1 to 5 and comparative example a, and are shown in table 3.

[ Table 3]

TABLE 3

<Newton's Ring variation A_590℃Newton's ring variation A _650℃Rate of change of Newton's Ring variation with respect to temperature>

The amount of change in Newton's Ring formation A was determined by the method described above for each of the glass molds of examples 1 to 5 and comparative example A_590℃Newton's ring variation A_650℃And the rate of change of the newton ring change amount with respect to temperature are shown in table 4. As a shape measuring device, a three-dimensional measuring machine (UA 3P manufactured by Panasonic Production Engineering) was used.

[ production and evaluation of optical elements ]

It is considered that, when optical elements are mass-produced by press molding, the occurrence of shape variations of the optical elements can be further suppressed as the shape change of the molding surface of the glass molding die is smaller. The degree of change in the shape of the molding surface of a glass molding die in mass production of optical elements by press molding can be evaluated by the following method.

The glass molding die was exposed to the molding temperature in 1 lens molding cycle, heated, and then cooled to around the glass transition temperature. It is considered that the change in shape of the molding surface of the glass molding die mainly occurs at a molding temperature high in temperature in 1 lens molding cycle, and the change increases with the increase in the number of times of molding. The number of newton rings is calculated by the above-described method from the shape of the glass mold used for molding a lens at a certain molding temperature (number of shots) X or more (for example, 50 shots or more) and the shape before use. As the shape measuring device, a three-dimensional measuring machine (UA 3P manufactured by Panasonic Production Engineering) was used. The difference D between the number of Newton rings before and after use (after use-before use) was divided by the number of injections X, and the obtained value D/X was defined as the amount of change in Newton rings Δ N per 1 injection, and the amount of change in Newton rings per 100 injections was multiplied by 100 times, thereby obtaining the amount of change in Newton rings 100D/X. The lower limit of the value of the number of embossings X for obtaining Δ N is set to 50 or more in consideration of the measurement error of Δ N. The upper limit of X is preferably 100 or less, more preferably 80 or less, and still more preferably 60 or less, because when X is increased to such an extent that no change in shape of the glass forming mold occurs, the apparent Δ N decreases and may be unsuitable for evaluation.

For example, the change Δ N in newton rings per injection at 590 ℃ can be determined as "the change Δ N in newton rings per injection at 590 ℃", by calculating the number of newton rings calculated by the above-described method from the shape of the glass mold used for molding a lens at a molding temperature of 590 ℃ by a predetermined number of times X (50. ltoreq. x.ltoreq.100) and the shape before use, and dividing the difference D in the number of newton rings before and after use of the lens molding (after use-before use) by the number of injections X. As the value thus obtained becomes smaller, it can be evaluated that the change in shape of the molding surface of the glass molding die is smaller when the optical element is mass-produced by press molding.

In examples 1 to 5 and comparative example A, the above-described glass forming mold having a concave shape was used as an upper mold and a lower mold, respectively, and by the method of the specific example described above, in the manufacturing apparatus for an optical element having the configuration shown in FIG. 1, precision press molding of a glass material to be formed of glass was repeated, assuming that the press molding temperature was 590 ℃ and the number of injections was X (50. ltoreq. X.ltoreq.60), to manufacture a glass optical element (lenticular lens). Then, 100D/X obtained by multiplying D/X by 100 times Δ N obtained by the above method is calculated and shown in table 4 as "a value obtained by multiplying 100 times the newton ring change amount Δ N per 1 injection at 590 ℃. The "value obtained by multiplying the newton ring change amount Δ N per 1 injection at 590 ℃ by 100 times" may be 0.00 or more than 0.00, and is preferably 1.00 or less, and is more preferably 0.90 or less, 0.80 or less, 0.70 or less, 0.60 or less, 0.50 or less, 0.40 or less, and 0.30 or less in this order. In comparative example a, the molding surface shape of the molding die changed greatly, and the molding could not be performed up to the injection number X, and therefore table 4 shows "could not perform molding".

[ Table 4]

TABLE 4

Finally, the above-described modes are summarized.

According to one aspect, there is provided a glass-made molding die for molding an optical element, the glass-made molding die having a Newton's Ring Change amount A before and after annealing at a temperature of 590 DEG C_590℃The number of the strands is 0.00 to 1.50.

According to the glass-made mold, when the optical element is mass-produced by press molding, the occurrence of shape variations in the optical element can be suppressed.

In one embodiment, the change amount of Newton's Ring A before and after annealing of the glass-forming mold at 650 ℃_650℃The number of the strands may be 0.00 to 1.50.

In one embodiment, in the above glass-made mold, a rate of change in newton ring variation with respect to temperature may be 0.00 × 10 in a temperature range of 590 to 650 ℃^-24.00X 10 at above strip/DEG C^-2Bars/° c.

In one embodiment, in the above glass-made molding die, a rate of change of the newton ring variation with respect to temperature may be 0.00 × 10 in a temperature range of 590 to 650 ℃^-22.50X 10 above strip/° C^-2Bars/° c.

In one embodiment, SiO is contained in the glass composition expressed by mol% of the glass₂With Al₂O₃The total content of (a) may be 60.0% or more.

In one embodiment, the glass is provided SiO in the glass composition expressed by mol% of the glass₂The content of Al can be 51.0 to 79.0 percent₂O₃The content is 8.0 to 24.0%, and the total content of MgO, CaO, SrO, and BaO may be 1.0 to 35.0%.

In one embodiment, the glass may be an aluminosilicate glass, and in the glass composition expressed in mol% of the glass, the MgO content may be 1.0% to 30.0%, the CaO content may be 0.0 to 15.0%, the SrO content may be 0.0 to 12.0%, the BaO content may be 0.0 to 12.0%, the ZnO content may be 0.0 to 10.0%, and Li may be 0.0 to 12.0%₂The content of O is 0.0-8.0%, Na₂O and K₂The total content of O may be 0.0 to 4.25%, ZrO₂The content of TiO can be 0.0-10.0%₂The content of La may be 0.0-6.0%₂O₃、Y₂O₃、Yb₂O₃、Ta₂O₅、Nb₂O₅And HfO₂The total content of (A) may be 0.0 to 4.0%.

In one embodiment, in the glass composition expressed by mol% of the glass, Li is contained₂O、Na₂O、K₂Total content of O relative to SiO₂、Al₂O₃And the molar ratio of the total content of MgO (Li)₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃+ MgO) may be in the range of 0.000 to 0.050.

According to one aspect, there is provided a method for manufacturing a glass molding die, the method including: extruding the glass blank for forming the forming mold in a state of being in contact with the surface of the female mold; and cooling the glass material for forming the forming mold in the contact state, wherein the cooling rate during the cooling is-30.0 ℃/min or less.

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

According to one aspect, there is provided a method for manufacturing an optical element, including press-molding a material to be molded with the glass molding die.

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

The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined not by the above description but by the claims, and includes all modifications within the meaning and scope equivalent to the claims.

For example, two or more of the embodiments described as examples or preferred ranges in the specification may be arbitrarily combined.

Claims

1. 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.

2. The glass-forming mold according to claim 1, wherein the amount of change in Newton's Ring A before and after annealing at a temperature of 650 ℃_650℃The number of the strands is 0.00 to 1.50.

3. The glass-made molding die according to claim 1 or 2, wherein a rate of change of the newton ring variation with respect to temperature is 0.00 x 10 in a temperature range of 590 ℃ to 650 ℃ ^-24.00X 10 at above strip/DEG C^-2Bars/° c.

4. The glass-forming mold according to any one of claims 1 to 3, wherein a rate of change in Newton's Ring variation with respect to temperature is 0.00 x 10 in a temperature range of 590 ℃ to 650 ℃^-22.50X 10 above strip/° C^-2Bars/° c.

5. The glass forming mold according to any one of claims 1 to 4, wherein in a glass composition represented by mol% of the glass,

SiO₂with Al₂O₃The total content of (A) is more than 60.0%.

6. The glass forming mold according to any one of claims 1 to 5, wherein in a glass composition represented by mol% of the glass,

SiO₂the content is 51.0 to 79.0 percent,

Al₂O₃the content is 8.0-24.0%, and,

the total content of MgO, CaO, SrO and BaO is 1.0-35.0%.

7. The glass forming mold according to any one of claims 1 to 6,

the glass is an aluminosilicate glass and the glass is a non-aluminosilicate glass,

in the glass composition expressed in mol% of the glass,

MgO content of 1.0-30.0%,

the content of CaO is 0.0-15.0%,

SrO content is 0.0-12.0%,

BaO content is 0.0-12.0%,

ZnO content of 0.0-10.0%,

Li₂the content of O is 0.0 to 8.0 percent,

Na₂o and K₂The total content of O is 0.0-4.25%,

ZrO₂The content is 0.0-10.0%,

TiO₂the content is 0.0 to 6.0%, and,

La₂O₃、Y₂O₃、Yb₂O₃、Ta₂O₅、Nb₂O₅and HfO₂The total content of (A) is 0.0-4.0%.

8. The glass forming mold according to any one of claims 1 to 7, wherein in a glass composition represented by mol% of the glass,

Li₂O、Na₂O、K₂total content of O relative to SiO₂、Al₂O₃And the molar ratio of the total content of MgO (Li)₂O+Na₂O+K₂O)/(SiO₂+Al₂O₃And + MgO) is in the range of 0.000 to 0.050.

9. A method for manufacturing a glass molding die according to any one of claims 1 to 8, comprising:

extruding the glass blank for forming the forming mold in a state of being in contact with the surface of the female mold; and

cooling the glass material for molding the molding die in the contact state,

the cooling rate in the cooling is-30.0 ℃/min or less.

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

11. A method for producing an optical element, comprising press-molding a material to be molded with the glass molding die according to any one of claims 1 to 8.

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