JP3270022B2 - Optical glass and optical products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical glass, a molding material comprising the optical glass, a method for producing the same, and an optical product obtained by using the optical glass as a material and a method for producing the same. Refractive index, high ~
The present invention relates to a medium-dispersed optical glass, a material for precision press molding comprising the optical glass, a method for producing the same, an optical product obtained by using the optical glass as a material, and a method for producing the same.

[0002]

2. Description of the Related Art In forming a desired optical system,
In general, it is necessary to combine various optical elements having different refractive indexes n _d and Abbe numbers ν _d . Therefore, the refractive index n _d
And various optical glasses having different Abbe numbers ν _d have been developed. For example, the high refractive index having a refractive index n _d is an Abbe number [nu _d is approximately 28 to 41 in approximately 1.7 or more, as the optical glass of high-dispersion, heavy barium flint glass, dense flint glass, lanthanum flint glass And various glasses classified as heavy lanthanum flint glass and the like have been developed (see JIS Z8120).

Incidentally, precision press molding is widely used at present as one method of forming optical products such as optical elements (lenses and prisms) and optical fiber fixing members with glass. Precision press molding when obtaining a molded product made of glass is performed by pressing a predetermined precision press molding material (glass preform) under high temperature using a mold having a cavity of a predetermined shape, This is for producing a glass molded article having a shape or a shape very similar to the shape. Each molding surface of a molding die used for precision press molding has high surface accuracy. When the molding die and the material for precision press molding (preliminary glass molding) are within a predetermined temperature range, By pressing the material for precision press molding (preliminary glass molding) using the mold, the shape of each molding surface is transferred to the material for precision press molding (preliminary glass molding).

[0004] In order to obtain a glass molded product by precision press molding, it is necessary to press-mold the material for precision press molding at a high temperature as described above. And high pressure is applied. Therefore, for precision press molding materials, (1) from the viewpoint of suppressing damage to the mold itself and the release film provided on the inner surface of the mold due to the high temperature environment during press molding. It is desired that the glass yield point be as low as possible,
(2) From the viewpoint of suppressing a reaction product from being generated by a reaction between the material for precision press molding and the mold and deteriorating the surface properties of the molded article, the reactivity with the mold is suppressed as low as possible. It is desired. further,
(3) From the viewpoint of environmental protection, it is desired not to contain lead oxide (PbO).

From the viewpoints of the above (2) and (3), a high refractive index, high to medium dispersion optical glass which is preferable as a material for precision press molding is a high refractive index, high to medium dispersion which does not contain lead oxide as an essential component. , Such as lanthanum flint glass or heavy lanthanum flint glass. High refractive index, high to medium dispersion optical glasses containing lead oxide as an essential component, for example, optical glasses classified as heavy barium flint glass or heavy flint glass, are considered from the viewpoints of the above (2) and (3). ,
It cannot be said that it is preferable as the material for precision press molding.

A high refractive index which does not contain lead oxide as an essential component,
The high to medium dispersion optical glass is generally a borate glass or a borosilicate glass, and examples of the optical glass include B ₂ O ₃ —SiO ₂ — disclosed in JP-A-61-232243. _{Li 2 O-CaO-La 2} O 3 -
TiO ₂ —ZrO ₂ —Nb ₂ O ₅ -based optical glass and SiO ₂ disclosed in JP-A-61-146730.
_{-B 2 O 3 -Li 2 O-} La 2 O 3 -ZrO 2 -Nb 2 O 5 system of the optical glass is known.

[0007]

There are various methods for producing a material for press molding used in precision press molding, depending on the type of a target molded product and the like. It is necessary to prepare a desired glass melt in a melting furnace, guide the glass melt to a desired location by an outflow pipe, and let it flow down from the outlet.

[0008] Pt (platinum) or a Pt alloy is generally used as a material for the melting furnace and the outflow pipe. A conventional high refractive index, high to medium dispersion which does not contain lead oxide as an essential component. An optical glass, that is, a conventional high refractive index, high to medium dispersion optical glass made of borate glass or borosilicate glass,
It is easily wetted with Pt or Pt alloy used as a material for melting furnaces and outflow pipes.

When the glass melt easily wets the outflow pipe made of Pt or Pt alloy, as shown in FIG. 1, the outflow pipe 1 is arranged so that the outflow port is directed vertically downward. However, a phenomenon in which a part 2a of the glass melt 2 flowing down from the outflow pipe 1 wets outside the front end on the outflow side of the outflow pipe 1 (hereinafter, this phenomenon is referred to as "wetting phenomenon"). As the diameter of the outflow pipe 1 becomes smaller, the wetting phenomenon becomes more prominent. Note that reference numeral 3 in FIG.
Indicates an outflow furnace for heating the outflow pipe 1.

In order to obtain a material for precision press molding for small optical products, for example, a material for precision press molding for small-diameter lenses, the diameter of the outflow pipe 1 is inevitably reduced, so that lead oxide is not an essential component. In the above-mentioned conventional high-refractive-index, high-medium dispersion optical glass, when the material for precision press molding for the small-sized optical product is obtained, the above-mentioned wetting-up phenomenon becomes remarkable. When the above wetting phenomenon becomes remarkable, (i) striae occurs in the glass gob when the glass melt is flowed down from the outflow pipe to obtain a glass gob, and as a result, from the glass gob, It becomes impossible to obtain an optical product having the desired optical characteristics, and (ii) the weight of the glass gob cannot be adjusted when the glass melt is allowed to flow down from the outflow pipe to obtain a glass gob. There arises a problem that the weight of the optical product to be obtained from the glass gob cannot be adjusted or a process for adjusting the weight of the optical product is required.

A first object of the present invention is to provide an optical glass in which the above wetting phenomenon hardly occurs, and which can easily obtain a glass having a high refractive index and a high to medium dispersion.
A second object of the present invention is to provide a precision press-molding material which can easily obtain a small-sized optical glass having a high refractive index and a high to medium dispersion, and a method for producing the same. The third object of the present invention is to provide a high refractive index and a high refractive index.
An object of the present invention is to provide an optical product and a method for manufacturing the same, which can easily obtain a small-sized product made of a medium-dispersed optical glass.

[0012]

The optical glass of the present invention, which achieves the first object, has a refractive index ( _nd ) containing silicon oxide and boron oxide of 1.7 or more and an Abbe number (ν).
_d ) The optical glass of Nos. 28 to 41, wherein the ratio of the content of silicon oxide to the content of boron oxide is larger than 0.78, and Pt or a Pt alloy at a predetermined temperature or a predetermined temperature range equal to or higher than the liquidus temperature. Has a contact angle of 40 ° or more and a sag point T _s of 580 ° C. or less (hereinafter, this optical glass is referred to as “optical glass I”).

Further, another optical glass of the present invention which achieves the first object contains silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide in a total amount of 63 wt% or more. The content of each of these components is 17 to 33 wt% of silicon oxide (however, 1
Excluding the cases of 7 wt% and 33 wt%, respectively. ), 1-25 wt% boron oxide, 5-5 lithium oxide
11 wt%, calcium oxide 5-27 wt% (however, 5 wt%
Except when it is%. ), 1 to 20 wt% of titanium oxide, 13 to 30 wt% of niobium oxide (excluding the case of 13 wt%), and the total amount of silicon oxide and boron oxide is 20 to 50 wt%. The ratio of the content of silicon oxide to the content of boron is greater than 0.78, lanthanum oxide is 0 to less than 16 wt%, and zinc oxide is 0 to 0 wt%.
12 wt%, 0-15 wt% barium oxide, 0-10 wt% zirconium oxide, 0-10 wt% strontium oxide
%, 0-6 wt% tungsten oxide, 0-7 wt% aluminum oxide, 0-5 wt% sodium oxide, 0-5 wt% potassium oxide, 0-5 wt% yttrium oxide, 0-5 wt% gadolinium oxide, Ytterbium oxide
~ 5wt%, tantalum oxide 0 ~ 5wt%, arsenic oxide 0 ~ 5wt%
It is characterized by containing 2 wt% of antimony oxide and 0 to 2 wt% of antimony oxide (hereinafter, this optical glass is referred to as “optical glass II”).

On the other hand, a material for precision press molding of the present invention, which achieves the second object, is characterized by comprising the optical glass of the present invention. In addition, the method for producing a material for precision press molding includes forming a glass gob obtained by dropping a glass melt from which the optical glass of the present invention is obtained from an outlet of an outflow pipe made of Pt or a Pt alloy. And a material for precision press molding.

An optical product of the present invention that achieves the third object is characterized by being made of the optical glass of the present invention.

The method for manufacturing an optical product according to the present invention is characterized in that the precision press-molding material of the present invention is placed in a mold having at least an upper mold and a lower mold as mold elements for forming a cavity having a predetermined shape. The material for precision press molding manufactured by the manufacturing method is arranged, and the material for precision press molding is precision press-molded to a predetermined shape using the above-mentioned mold under the condition that the material for precision press molding is softened by heating. It is characterized by including a process.

[0017]

Embodiments of the present invention will be described below in detail. First, the optical glass I of the present invention will be described. As described above, the optical glass I of the present invention is an optical glass containing silicon oxide and boron oxide and having a refractive index (n _d ) of 1.7 or more and an Abbe number (ν _d ) of 28 to 41, The ratio of the content of silicon oxide to the content of boron oxide is greater than 0.78, and the contact angle with Pt or a Pt alloy becomes 40 ° or more at a predetermined temperature or a predetermined temperature region or higher, and the yield point T _s
Is 580 ° C. or lower.

Here, "Pt alloy" as used in the present specification is used as a material of an outflow pipe used to guide a molten glass (glass melt) from a melting furnace or a molten glass tank to a desired place. Means Pt alloy. Specific examples of the “Pt alloy” include, for example, Au
An alloy of Pt with at least one selected from the group consisting of (gold), Rh (rhodium), Ir (iridium), and Pd (palladium). Among them, Pt is 8
Those containing 0 at% or more, containing 20 at% or less of Au, and containing 10 at% or less in total of Rh, Ir and Pd (including the case where neither Rh, Ir nor Pd is contained), particularly 95 Pt. -5Au alloy is used as a material for the above-mentioned outflow pipe.

The term "contact angle" as used herein means the magnitude of the contact angle between glass and a Pt plate or a Pt alloy plate, measured as follows.
First, as shown in FIG. 2 (a), a plate 5 made of Pt or a Pt alloy (horizontal surface is mirror-finished. Its size in plan view is 10 × 10 mm. 4 × 4 near the center of plate 5 ”)
The glass sample 6a having a size of × 4 mm is placed thereon, and the glass sample 6a is heated to a desired temperature not lower than its liquidus temperature (LT) in the atmosphere and kept in this state for 30 minutes. After the glass sample is once melted, it is annealed. This annealing is performed by holding the molten glass sample at the glass transition point temperature for 1 hour, and then -30 ° C /
It is performed by cooling to room temperature under a rate of temperature decrease of hr. Next, as shown in FIG. 2B, the solidified glass sample 6b is regarded as a liquid, and the contact angle θ between the glass sample 6b and the plate 5 is measured.

The “plate made of Pt or Pt alloy whose surface is mirror-finished” means that the surface has an _Rz of 500 to 500.
Pt processed to 10,000 angstroms
Or a plate made of Pt alloy. The smaller the value of _Rz, the less likely the measurement results to vary,
Within the above range, for example, it may be 5000 to 10000 angstroms, or 1000 to 1000 angstroms.
It may be 0 Å.

The inventor of the present invention has determined that the contact angle is 40 or less at a temperature or a temperature range when the glass melt (molten glass) flows out from the outflow pipe, that is, at a predetermined temperature or temperature range higher than the liquidus temperature of the glass. By selecting the composition of the glass so as to be equal to or more than 0 °, for example, even when using a small-diameter outflow pipe (meaning an outflow pipe having an inner diameter of 1 to 8 mm; the same applies hereinafter),
It has been found that the aforementioned "wetting up phenomenon" can be suppressed.

If the glass satisfies the above conditions for the contact angle, a glass gob with less striae and weight variation can be easily formed even if the glass melt flows down from the small-diameter outflow pipe. become. As a result, it is possible to obtain a precision press-molding material (glass preform) for a small optical product (for example, a small-diameter lens) having desired optical characteristics and weight with high productivity, It becomes easy to obtain an optical product, for example, an optical element such as a lens, manufactured by molding a material into a predetermined shape by a precision press molding method or another molding method with high productivity. The above contact angle is preferably from 40 ° to about 120 °, and is preferably about 5 °.
The angle is more preferably from 0 ° to about 120 °, and still more preferably from about 60 ° to about 120 °.

The heating temperature of the glass sample at the time of obtaining the contact angle (heating temperature for once melting the glass sample) depends on the temperature of the glass melt at the time of flowing the glass melt from the outflow pipe. , Usually its liquidus temperature L. Since T is within the range of [(LT) +40] ° C., it is preferable to set the temperature to a predetermined temperature within this temperature range,
The temperature is more preferably set to a predetermined temperature within a temperature range of [(LT) +10] ° C to [(LT) +20] ° C.

Further, the present inventors have used silicon oxide and boron oxide as glass-forming components, and have set the ratio of the silicon oxide content to the boron oxide content to 0.1%.
By making it larger than 78, the above conditions for the contact angle are satisfied, and the refractive index (n _d ) is 1.7 or more and the Abbe number (ν _d ) is 28 to 41. It has been found that an optical glass can be easily obtained, and that its yield point can be lowered to 580 ° C. or lower.

The optical glass I of the present invention has been invented based on the above two findings. Therefore, even when the glass melt flows down from a small-diameter outflow pipe made of Pt or a Pt alloy, the optical glass I hardly causes the above-mentioned wetting phenomenon, and has a high refractive index and a high to medium dispersion. It is an optical glass that is easy to obtain.
If it is difficult for the above-mentioned wetting phenomenon to occur when the glass melt flows down from a small-diameter outflow pipe made of Pt or a Pt alloy, when obtaining a material for precision press molding having a diameter of 1 to 5 mm, The above-mentioned wetting phenomenon is unlikely to occur even when the glass melt flows down from a small-diameter outflow pipe (inner diameter is about 1 to 3 mm) made of Pt or Pt alloy, so that the precision press molding is performed. It is possible to easily obtain the material for use with high weight accuracy.

The optical glass I having the above-mentioned advantages has a contact angle of 40 by appropriately selecting the composition.
° or more, the yield point is 580 ° C or less, and the optical constants (n _d ,
ν _d ) can be obtained. The refractive index n _d is approximately 1.70 or more, the Abbe number v _d is approximately 28 to 41, the contact angle is 40 ° or more, and the yield point is 5
From the viewpoint of obtaining the optical glass I having a temperature of 80 ° C. or lower, it is preferable to contain lithium oxide, calcium oxide, titanium oxide, and niobium oxide in addition to silicon oxide and boron oxide.

Of the above glass components, both silicon oxide and boron oxide are required as glass forming components. Silicon oxide is also an important component for obtaining an optical glass having low wettability with Pt and a Pt alloy. Lithium oxide is a component for improving the meltability of the silicon oxide, an important component even for obtaining a glass having low yield point T _s.

Calcium oxide is a component that functions to lower the liquidus temperature in order to obtain an optical glass having a high refractive index and a high to medium dispersion, and at the same time, an optical glass having low wettability with Pt and a Pt alloy. It is a necessary component for obtaining. Both titanium oxide and niobium oxide are necessary components for obtaining a high-refractive-index optical glass, and also necessary components for obtaining a high-dispersion optical glass.

When a material for precision press molding is to be obtained by using the optical glass I, it is necessary to prevent the mold from being damaged during precision press molding.
Of it it is not preferably to the yield point T _s to approximately 580 ° C. or less, by combining the above six kinds of the glass components, also by adding other ingredients as needed, the refractive index n _d Is approximately 1.70 or more, the Abbe number ν _d is approximately 28 to 41, the contact angle is 40 ° or more, and the yield point T _s is approximately 580 ° C. or less.
Can be easily obtained.

The optical glass I having a refractive index n _{d of} about 1.70 or more, an Abbe number ν _{d of} about 28 to 41, the contact angle of 40 ° or more, and a yield point T _{s of} about 580 ° C. or less.
Can be obtained by, for example, making the composition as shown in the following (1) or (2).

(1) The total amount of silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide is at least 63 wt%, and the content of each of these components is 17 to 33 wt% of silicon oxide (provided that 17 wt% and 33 wt%, respectively.),
Boron oxide 1-25 wt%, lithium oxide 5-11 wt%,
5 to 27% by weight of calcium oxide (excluding 5% by weight), 1 to 20% by weight of titanium oxide, 1 of niobium oxide
3 to 30% by weight (excluding 13% by weight)
And the total amount of the silicon oxide and the boron oxide is 20 to 50 wt%, lanthanum oxide is less than 0 to 16 wt%, zinc oxide is 0 to 12 wt%, and barium oxide is 0 to 15 wt%.
wt%, 0-10 wt% zirconium oxide, 0-10 wt% strontium oxide, 0-6 wt% tungsten oxide
%, Aluminum oxide 0-7 wt%, sodium oxide 0-5 wt%, potassium oxide 0-5 wt%, yttrium oxide 0-5 wt%, gadolinium oxide 0-5 wt%, ytterbium oxide 0-5 wt%, 0-5 tantalum oxide
wt%, arsenic oxide 0-2 wt%, antimony oxide 0-2
wt% respectively. Of course, in the glass composition at this time, the ratio of the content of silicon oxide to the content of boron oxide is set to be larger than 0.78 as described above.

(2) The total amount of silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide is at least 63 wt%, and the content of each of these components is 17 to 33 wt% of silicon oxide (however, 17 wt% and 33 wt%, respectively.),
Boron oxide 1-25 wt%, lithium oxide 5-11 wt%,
5 to 27% by weight of calcium oxide (excluding 5% by weight), 1 to 20% by weight of titanium oxide, 1 of niobium oxide
3 to 30% by weight (excluding 13% by weight)
And the total amount of the silicon oxide and the boron oxide is 20 to 50 wt%, lanthanum oxide is less than 0 to 16 wt%, zinc oxide is 0 to 12 wt%, and barium oxide is 0 to 15 wt%.
wt%, 0-10 wt% zirconium oxide, 0-10 wt% strontium oxide, and 0-2 wt% antimony oxide. Of course, in the glass composition at this time, the ratio of the content of silicon oxide to the content of boron oxide is set to be larger than 0.78 as described above.

The reason why it is preferable to set the content of each component in the above-mentioned compositions (1) and (2) within the above range is as follows. That is, the content of silicon oxide is 17
If it is less than wt%, it may be difficult to obtain an optical glass having the above-mentioned contact angle of 40 ° or more.
% Or more, it may be difficult to obtain an optical glass having a high refractive index. The content of silicon oxide is 17.5
More preferably, it is about 31% by weight.

If the content of boron oxide is less than 1 wt%, vitrification may be difficult, and if the content is less than 25% by weight.
If the content exceeds wt%, it may be difficult to obtain an optical glass having a high refractive index, and striae may be easily generated in the glass due to volatilization of the boron oxide. More preferably, the content of boron oxide is 1.5 to 22 wt%.

[0035] In less than 5 wt% content of lithium oxide or have the unmelted material of silicon oxide is likely to remain in the glass, it is difficult to yield point T _s to obtain a generally 580 ° C. or less of the optical glass When the content exceeds 11% by weight, the liquidus temperature of the glass may be increased to lower the mass productivity, and it may be difficult to obtain an optical glass having a high refractive index. . The content of lithium oxide is more preferably from 5.3 to 9.5 wt%, even more preferably from 6.5 to 9.5 wt%.

If the content of calcium oxide is less than 5 wt%, the above-mentioned effects caused by the inclusion of calcium oxide may not be substantially obtained. If the content exceeds 27 wt%, the liquidus temperature of the glass may be reduced. May be higher. The content of calcium oxide is 5.5 to 2
More preferably, it is 4.5 wt%, and 6.5 to 22 wt%.
% Is more preferable.

When the content of titanium oxide is less than 1% by weight, the above-mentioned effects caused by the inclusion of titanium oxide may not be substantially obtained, and the content may be 20%.
If the content exceeds wt%, the liquidus temperature of the glass may increase, and coloring may increase. More preferably, the content of titanium oxide is 2.5 to 18 wt%.

If the content of niobium oxide is 13 wt% or less, the above-mentioned effects caused by the inclusion of niobium oxide may not be substantially obtained. If the content exceeds 30 wt%, the glass liquid may not be obtained. Phase temperature may be high. The content of niobium oxide is 13-27.5 wt.
% (However, excluding the case of 13 wt%).

Even if the contents of the above-mentioned silicon oxide, lithium oxide, calcium oxide, titanium oxide, niobium oxide and boron oxide are within the above-mentioned ranges, if the total amount of these essential components is less than 63 wt%, the refractive index will be low. The ratio n _d is approximately 1.70 or more, and the Abbe number ν _d is approximately 28 to 41.
In, it may become difficult to obtain an optical glass glass deformation point T _s is approximately 580 ° C. or less. The total amount is
More preferably, it is at least 65 wt%.

The total amount of silicon oxide and boron oxide is 2
If the amount is less than 0 wt%, vitrification may be difficult, and if the total amount exceeds 50 wt%, it may be difficult to obtain an optical glass having a high refractive index. More preferably, the total amount of silicon oxide and boron oxide is 24-43 wt%.

Further, if the ratio of the content of silicon oxide to the content of boron oxide is 0.78 or less, it may be difficult to obtain an optical glass having the contact angle of 40 ° or more. If the ratio exceeds 30, the liquidus temperature may increase. This ratio is particularly preferably from 0.8 to 27.

On the other hand, among the substances listed as components whose content may be 0 wt% (hereinafter, these components are referred to as “optional components”), lanthanum oxide, barium oxide, zirconium oxide, strontium oxide, tungsten oxide , Aluminum oxide, yttrium oxide, gadolinium oxide, ytterbium oxide and tantalum oxide function to lower the liquidus temperature of the glass by adding an appropriate amount, respectively, and by appropriately selecting the content of these components within the above range. It is possible to adjust the optical constants (n _d , ν _d ) of the glass. However, if the content of any one of these components exceeds the above range, the liquidus temperature of the glass may increase. More preferable contents of these components are 0 to 15% by weight of lanthanum oxide, 0 to 12% by weight of barium oxide, 0 to 7% by weight of zirconium oxide,
Strontium oxide 0-8wt%, Tungsten oxide 0-0
4 wt%, aluminum oxide 0-5 wt%, yttrium oxide 0-3 wt%, gadolinium oxide 0-3 wt%, ytterbium oxide 0-3 wt%, tantalum oxide 0-3 wt%. And about lanthanum oxide, the content is set to 0.
More preferably, it is set to 〜13 wt%.

[0043] Also, zinc oxide mentioned as optional ingredients, sodium and potassium oxide oxidation serves to lower the yield point T _s of the glass by the appropriate amount of additives. However, if the content of any one of these components exceeds the above range, the liquidus temperature of the glass may increase, and the devitrification may increase. More preferred contents of these components are zinc oxide 0 to 11 wt%, sodium oxide 0 to 3
wt% and potassium oxide 0 to 3 wt%.

The arsenic oxide and antimony oxide given as optional components each function as a defoaming agent or a fining agent when added in appropriate amounts. However, if the content of any one of these components exceeds the above range, the liquidus temperature of the glass may increase. The more preferred content of these components is 0 to 2 wt.
%, And 0 to 2% by weight of antimony oxide. Among the optional components described above, lanthanum oxide, zirconium oxide and zinc oxide have an advantage that the devitrification resistance of the glass is hardly reduced as compared with the other optional components described above.

The optical glass I of the present invention may contain phosphorus oxide, germanium oxide, cesium oxide, manganese oxide, manganese oxide, tellurium oxide, bismuth oxide or lead oxide as long as the object of the present invention is not impaired. Good. However, since phosphorus oxide has the effect of reducing the contact angle of glass with Pt or a Pt alloy, its content is preferably less than 4% by weight, more preferably less than 3% by weight.

In obtaining the optical glass I of the present invention described above, first, desired raw materials are weighed in predetermined amounts in accordance with the composition of the target optical glass, and these raw materials are mixed to obtain a prepared raw material. . Next, this prepared raw material was added to 1
The glass melt is melted in a melting furnace heated to 000 to 1350 ° C., and the glass melt is clarified and stirred to be homogenized. Thereafter, the homogenized glass melt is guided to a desired location by an outflow pipe, and the glass melt flowing down from the outflow pipe can be obtained by being gradually cooled while being formed into a desired shape or while being formed. At this time, B ₂ O ₃ and H ₃ BO are used as raw materials for boron oxide.
₃ etc., and the raw material for aluminum oxide is Al
₂ O ₃ , Al (OH) _3, etc., and as a raw material for other components, carbonates, nitrates, oxides, etc. of cations constituting the target component can be used as appropriate.

Next, the optical glass II of the present invention will be described. As described above, the optical glass II of the present invention comprises silicon oxide, boron oxide, lithium oxide, calcium oxide,
It contains titanium oxide and niobium oxide in a total amount of 63% by weight or more, and the content of each of these components is 17 to 33% by weight of silicon oxide (excluding cases where the content is 17% by weight and 33% by weight, respectively). ), Boron oxide 1
-25 wt%, lithium oxide 5-11 wt%, calcium oxide 5-27 wt% (except when it is 5 wt%), titanium oxide 1-20 wt%, niobium oxide 13-3
0 wt% (excluding the case of 13 wt%), and the total amount of the silicon oxide and the boron oxide is 2%.
0-50 wt%, the ratio of silicon oxide content to boron oxide content is greater than 0.78, lanthanum oxide is less than 0-16 wt%, zinc oxide is 0-12 wt%, barium oxide is 0-15 wt% , Zirconium oxide is 0-10wt
%, 0-10 wt% strontium oxide, 0-6 wt% tungsten oxide, 0-7 wt% aluminum oxide, 0-5 wt% sodium oxide, 0-5 wt% potassium oxide.
%, Yttrium oxide 0-5 wt%, gadolinium oxide 0-5 wt%, ytterbium oxide 0-5 wt%, tantalum oxide 0-5 wt%, arsenic oxide 0-2 wt%, antimony oxide 0-2 wt% It is characterized by containing.

That is, the optical glass II of the present invention is one of the preferred embodiments of the optical glass I of the present invention described above. Therefore, a specific description of each component is omitted here. The optical glass II has a refractive index n _d of approximately 1.70 or more, an Abbe number ν _d of approximately 28 to 41,
When the above-mentioned contact angle is 40 ° or more, the yield point T _s is approximately 58
It is an optical glass that can easily be obtained at a temperature of 0 ° C. or lower.

Next, the material for precision press molding of the present invention will be described. As described above, the material for precision press molding of the present invention is obtained by molding the optical glass I or the optical glass II of the present invention into a predetermined shape. The shape of the material for precision press molding is not particularly limited, and may be spherical, marble, plate, or the like depending on the shape of the molded product to be obtained by precision press molding using the material for precision press molding. A pillar shape, a go stone shape, or the like is appropriately selected.

The material for precision press molding of the present invention has the above-mentioned optical glass I or optical glass II of the present invention, that is, the wet phenomena described above hardly occurs even when it flows down from a small-diameter outflow pipe, and For precision press molding, it is easy to obtain optical glass with high refractive index and high to medium dispersion, so it is easy to obtain optical glass with high refractive index and high to medium dispersion. Material.

The production method for obtaining the material for precision press molding of the present invention having the above-mentioned advantages is not particularly limited, and cold working such as grinding and polishing may be performed according to the desired shape. Methods such as the method of the invention described in JP-A-61-146721 and the method of the invention described in JP-B-7-51446 can be appropriately applied.

Among these methods, from the above-mentioned characteristics of the optical glass I and the optical glass II of the present invention and the production of the target material for precision press molding to the production of an optical product using the material for precision press molding. Taking into account the productivity of the present invention, the method for producing a material for precision press molding of the present invention, that is, the above-mentioned glass melt from which the optical glass I or the optical glass II of the present invention is obtained is made of Pt or Pt alloy. A method of forming a glass gob obtained by dripping from an outlet of an outflow pipe to obtain a material for precision press molding,
It is preferable to obtain the target material for precision press molding.

Next, the optical product of the present invention will be described. As described above, the optical product of the present invention is characterized by comprising the optical glass I or the optical glass II of the present invention. Here, specific examples of the optical product include optical elements such as a lens and a prism.

In consideration of the productivity of the objective optical product, the optical product is manufactured by precision press-molding the above-described material for precision press molding of the present invention using a molding die having a cavity of a predetermined shape. It is preferred that it is. In this case, as the type of the optical product is not limited, the shape of the material for precision press molding is not particularly limited, and according to the type and shape of the target optical product, for example, marble Shape, flat plate, columnar shape, spherical shape, stone shape, etc. can be selected as appropriate. However, as described above, the characteristics of the optical glass I and the optical glass II of the present invention and the productivity from the production of the target material for precision press molding to the production of an optical product using the material for precision press molding are considered. Considering the above, it is preferable that the material for precision press molding is manufactured by the method for manufacturing a material for precision press molding of the present invention described above.

As described above, the optical product of the present invention comprises the optical glass I or the optical glass II of the present invention. Then, as described above, the optical glass I of the present invention has a high refraction index and a high to medium dispersion in which the wetting phenomenon described above does not easily occur even when the optical glass I flows down from a small-diameter outflow pipe. It is an optical glass that can be easily manufactured and has a deformation point of 580 ° C. or less. Further, as already described, the optical glass II of the present invention is a high-refractive-index, high-to-medium dispersion optical glass in which the wetting phenomenon described above is unlikely to occur even when flowing down from a small-diameter outflow pipe, It is an optical glass whose yield point is easy to obtain at 580 ° C or lower. Therefore, the optical product of the present invention is an optical product that is easy to obtain a small one made of optical glass having a high refractive index and a high to medium dispersion, and a precision press molding method is used in manufacturing the optical product. It is an optical product that is easy to apply.

When a lens is to be obtained as an optical product of the present invention, for example, a lens of various sizes, for example, a large lens having a diameter exceeding 20 mm, a lens having a diameter of 2
Small lens of 0 mm or less, micro lens of 12 mm or less in diameter, super micro lens of 8 mm or less in diameter, 4 m in diameter
m can be obtained.
These lenses can be used by being incorporated in, for example, a camera or a VTR, and can also be used as an objective lens, a collimator lens, or the like used in a laser optical system in an optical pickup or the like. When trying to manufacture the optical product of the present invention by precision press molding,
For example, an optical product manufacturing method of the present invention described below can be applied.

Next, a method for manufacturing the optical product of the present invention will be described. The method of manufacturing an optical product of the present invention is to manufacture the above-described optical product of the present invention by using a precision press molding method, and the manufacturing method is, as described above, for forming a cavity having a predetermined shape. The precision press molding material manufactured by the method for manufacturing a precision press molding material of the present invention described above is arranged in a molding die having at least an upper mold and a lower mold as mold elements for the precision press molding. The method includes a step of precision press-molding the material for precision press molding into a predetermined shape using the molding die in a state where the material is softened by heating. The above-mentioned molding die may form a cavity of a predetermined shape by an upper die and a lower die, or may form a cavity of a predetermined shape by an upper die, a lower die, and a guide die (body die). There may be.

The precision press molding using the mold is as follows.
The viscosity of the material for precision press molding is approximately 10 ⁶ to 10
⁹ poise (approximately 10 ⁵ to 10 ⁸ Pa · s), preferably approximately 10 ⁷ to 10 ⁹ poise (approximately 10 ⁶ to 10 ⁸ Pa · s), more preferably approximately 10 ^7.5 to ^108.5 poise (approximately 10 10
It is preferably performed at ^6.5 to ^107.5 Pa · s).

By this precision press molding, a desired optical product (the optical product of the present invention described above) or an optical product having a shape very close to the final shape of the optical product (the optical product is also the optical product of the present invention described above) One of them.)
Can be obtained. When an optical product having a shape very close to the final shape of the target optical product is obtained, after performing precision press molding, a predetermined post-process is performed as necessary to obtain a desired optical product (this optical product). The product is also one of the optical products of the present invention described above.)

[0060]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to the following examples. Examples 1 to 29 and Comparative Examples 1 to 5 First, for each example or each comparative example, Table 1, Table 2, Table 3,
Predetermined amounts of desired raw materials were weighed so that the glass compositions shown in Table 4, Table 5, or Table 6 were obtained, and these raw materials were mixed to obtain a prepared raw material. Next, for each of the examples or comparative examples, the above prepared raw material was melted in a melting furnace heated to 1000 to 1350 ° C. to obtain a glass melt, and the glass melt was clarified and homogenized by stirring. After casting into a mold having a shape, the resultant was gradually cooled to obtain a target optical glass.

At this time, the raw material for boron oxide is H
₃ BO ₃ , Al (OH) ₃ as a raw material for aluminum oxide, and these oxides as raw materials for lithium oxide, sodium oxide, potassium oxide, calcium oxide and barium oxide. Carbonate for the cation element used, strontium nitrate as a raw material for strontium oxide, and oxide as a raw material for other components were used.

For each of the optical glasses obtained as described above, the refractive index n _d , Abbe number ν _d , yield point T _s , liquid phase temperature L.D. T and the contact angle were measured as follows. These results are also shown in Tables 1 to 6. -Refractive index n _d and Abbe number ν _{d The} rate of temperature decrease when the glass melt cast in the mold is gradually cooled
The target optical glass was obtained at 30 ° C./h, and the optical glass was measured. Measurement was performed under the condition of a temperature rising rate of 8 ° C./min using a yield point T _s thermal expansion measuring instrument. Liquid phase temperature L. T First, a predetermined number of samples were prepared for each of the examples and comparative examples.
These samples were placed in a devitrification test furnace provided with a temperature gradient of 500 to 1100 ° C., held for 30 minutes, and then cooled to room temperature. Next, the presence or absence of crystals in these samples was observed under a microscope with a magnification of 100 times, and the lowest devitrification test temperature at which no crystals were found in the samples was taken as the liquidus temperature.

Contact Angle A plate 5 (see FIG. 2) made of 95Pt-5Au is used, and the heating temperature for once melting the glass sample is determined by the liquidus temperature of the glass sample. The temperature was measured at T + 20 ° C. by the method described above. In addition, the value of the contact angle measured as described above is the value obtained when the contact angle between the glass sample and the plate 5 (see FIG. 2) in a molten state under the above conditions is measured using a high-temperature microscope. It was confirmed that the value was almost the same.

[0064]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6] As shown in Table 1 to Table 5, the optical glasses obtained in Examples 1 to 29, the refractive index n _d 1.7209 to 1.8
197, a high refractive index, high to medium dispersion optical glass having an Abbe number ν _d of 28.6 to 40.9, and the contact angle of these optical glasses is as large as 53 to 65 °. Accordingly, each of the optical glasses obtained in Examples 1 to 29 has a glass melt of Pt having a small inner diameter of, for example, 1 to 8 mm.
The "wetting up phenomenon" described above is unlikely to occur even when flowing down from an outflow pipe made of Pt or Pt alloy.

On the other hand, as shown in Table 6, the optical glasses obtained in Comparative Examples 1 and 2 each had a high refractive index and a high refractive index.
In these optical glasses, the ratio of the content of silicon oxide to the content of boron oxide is 0.11 or 0.18, which is out of the limited range in the present invention. Angle 35 ° or 34 °
And small. The optical glass obtained in Comparative Example 3 is a glass having a high refractive index and a high dispersion corresponding to the glass of Example 6 described in JP-A-61-232243.
In this optical glass, the ratio of the content of silicon oxide to the content of boron oxide is 0.76 wt%, which is out of the limit range in the present invention, and the contact angle is as small as 37 °. As described above, since the optical glass obtained in Comparative Examples 1 to 3 has a small contact angle, when the glass melt flows down from the outflow pipe, the above-mentioned “wetting phenomenon” is likely to occur. It is.

The optical glass obtained in Comparative Example 4 is disclosed in
This optical glass corresponds to the glass of Example 10 described in JP-146730A, and the optical glass is 1.71.
It has a high refractive index of 13. The contact angle is as large as 45 °. However, since the Abbe number ν _d of this optical glass is as large as 45, the optical glass is not the high to medium dispersion optical glass aimed at by the present invention.

The optical glass obtained in Comparative Example 5 is disclosed in
This is a high refractive index, high to medium dispersion optical glass corresponding to the glass of Example 11 described in JP-146730A. However, in this optical glass, the ratio of the content of silicon oxide to the content of boron oxide is 0.1%.
7 wt%, which is outside the limited range of the present invention, and the contact angle is as small as 37 °. Therefore, when the glass melt of the optical glass flows down from the outflow pipe, the above-mentioned "wetting phenomenon" is likely to occur.

For example, as one method for mass-producing small lenses by precision press molding, a predetermined glass melt is
A glass gob obtained by dropping from an outlet of an outflow pipe made of t or Pt alloy is formed to obtain a material for precision press molding such as a sphere, a true sphere or a stone, and the material for precision press molding is formed into a predetermined shape. There is a method of precision press-molding the lens using a mold having the above cavity. As described above, the glass melt from which the optical glass having the composition shown in Examples 1 to 29 is obtained has a large contact angle of 53 to 65 ° according to the present invention. It is suitable as a material for obtaining a material for precision press molding.

Actually, a glass melt (the temperature at which the viscosity becomes 8 poise (0.8 Pa · s)) from which an optical glass having the composition shown in Examples 1 to 29 was obtained was applied to an inner diameter of 2 m.
When a predetermined number of precision press-molding materials for microlenses were continuously produced by dropping from a m-Pt alloy (95Pt-5Au) outflow pipe, a precision press-forming material having no striae was obtained. These precision press molding materials have small weight variations among the individual materials.

Hereinafter, with respect to some of the glass melts from which the optical glasses having the compositions shown in Examples 1 to 29 are obtained, the glass melt is a small precision press molding material or a small precision press molding. The fact that the material is suitable for mass-producing products will be described more specifically.

Measurement of Weight Difference A glass melt from which an optical glass having the composition shown in Example 11 was obtained was prepared, and a Pt alloy outflow pipe having an inner diameter of 2 mm and arranged so that the outlet was directed vertically downward. The glass melt is guided to a desired location, and a glass gob that is continuously dropped from the outlet of the Pt alloy outflow pipe is sequentially and continuously formed using a plurality of molds to have a predetermined shape. A total of 1000 glass molded products were obtained. Then, for these glass molded articles, the following equation: Weight difference (%) = [(maximum weight−minimum weight) / reference weight]
× 100 Maximum weight: the weight of the heaviest of the above 1000 glass molded products Minimum weight: the weight of the lightest of the above 1000 glass molded products Reference weight: The weight difference is determined by the design weight of the glass molded product Was. Further, for each of the optical glass having the composition shown as Comparative Example 1 and the optical glass having the composition shown as Comparative Example 2, the weight difference was determined in the same manner as described above.

As a result, the glass molded article produced from the glass melt from which the optical glass having the composition shown in Example 11 was obtained had a small weight difference of 0.3%, whereas Comparative Example 2 A glass molded product produced from a glass melt from which an optical glass having the composition shown was obtained had a weight difference of 1.3.
%, And the glass molded article produced from the glass melt from which the optical glass having the composition shown in Comparative Example 1 was obtained had a larger weight difference of 1.5%.

The above-mentioned weight difference indicates the degree of weight variation between the obtained glass molded products. If the weight difference exceeds 1% when obtaining an optical product, it cannot be used as a product. In some cases. For example, in a precision press molding material for obtaining a small optical product (an optical product having a weight of 100 mg or less), the weight variation is ± 2.
% Or less, and preferably ± 1% or less. In addition, optical products larger than small items (weight 10
(More than 0 mg) in a precision press-molding material to obtain a weight variation of preferably ± 5% or less, more preferably ± 3% or less,
It is particularly preferable to be ± 1% or less. Therefore, the optical glass of Example 11 capable of obtaining a glass molded product having a weight difference of 0.3% as described above is suitable as a material glass when mass-producing optical products.

Example 30 (Production of a material for precision press molding) First, a concave portion having a predetermined shape and a gas blowing hole opening at the bottom of the concave portion were provided, and the vertical cross section of the concave portion was vertical. A predetermined number of molds having a trumpet shape opened upward (vertically upward during use) were prepared. Also,
A glass melt from which an optical glass having the same composition as the optical glass obtained in Example 1 was obtained was prepared. And, Tokuhei 7-51
According to the molding method described in Japanese Patent No. 446, a predetermined number of spherical molded articles were obtained from the glass melt.

The molding conditions at this time were the same as the molding conditions shown in the column of "Experimental result 1" in the publication. That is, the “spread angle θ” of the concave portion in each of the molds was 15 °, the diameter of the pores was 2 mm, and
The glass melt was guided vertically above the above-mentioned mold by an outflow pipe having an inner diameter of 1 mm and a tip having an outer diameter of 2.5 mm which was disposed so that the outflow port was directed vertically downward, and its viscosity was 8 poise (0 poise). (0.8 Pa · s), and spontaneously dropped from here. Then, air of 1 liter per minute is blown out from the gas blowout pores in the above-mentioned mold in advance, and the blowout of the air sufficiently cools the glass lump naturally dropped from the outflow pipe. Continued until Under the above conditions, the glass lump spontaneously dropped from the outflow pipe is received by the recess without almost contacting the inner surface of the recess of the mold, and rotates in a state of slightly floating with little contact, Sphere.

Each of the spherical molded products thus obtained exhibited a spherical shape having a high sphericity of 4.92 mm ± 0.04 mm, and no scratches or stains were observed on the surface. The weight accuracy is 220mg ± 0.5
mg was high. These molded products have, for example, a high refractive index,
It is suitable as a material for precision press molding when a high to medium dispersion aspherical lens is obtained by precision press molding.

Example 31 (Manufacture of optical product) The material for precision press molding obtained in Example 30 was used as a material to be molded, and the material to be molded was precision press molded by the precision press molding apparatus shown in FIG. 6.4 mmφ aspherical lens. The molding conditions at this time, the viscosity of the molded product of the molding temperature the (viscosity of the glass) is 10 ⁹ poise (1
0 ⁸ Pa · s) and press pressure 180 kg /
cm ² and the press time was 10 seconds.

The precision press molding apparatus 1 shown in FIG.
In 1, a molding die 14 composed of an upper die 14a, a lower die 14b, and a guide die (body die) 14c is placed on a support base 13 provided at one end of a support rod 12, and these are formed by a lower die. An object to be molded (a material for precision press molding) 15 is placed on the molding surface of 14b, the upper die 14a is placed thereon, and then placed in a quartz tube 17 around which a heater 16 is wound around the outer periphery. The upper mold 14a is a movable mold,
At the time of precision press molding, a load is applied by a push rod 18 from vertically above the upper mold 14a. A thermocouple 19 is inserted into the inside of the lower mold 14b via the support rod 12 and the support base 13, and the temperature of the molding die 14 is monitored using the thermocouple 19. You.

The aspherical lens thus obtained is
The shape accuracy was extremely high. In addition, since the weight variation of the above-mentioned molded article (material for precision press molding) 15 is very small at 0.45% (see Example 30), the volume of the cavity of the mold 14 in precision press molding is small. There was no excess or deficiency in the volume of the workpiece (material for precision press molding) 15, and as a result, even when the aspherical lenses were mass-produced, the weight variation among the individual aspherical lenses was very small. .

[0080]

As described above, in the optical glass of the present invention, even when the glass melt flows down from a small-diameter outflow pipe made of Pt or a Pt alloy, a part of the glass melt flows out of the outflow pipe. Is a high-refractive-index, high-to-medium dispersion optical glass in which the phenomenon that the outside of the tip of the substrate does not wet easily occurs. Therefore, according to the present invention, it becomes easy to mass-produce small optical products made of optical glass having a high refractive index and high to medium dispersion.

[Brief description of the drawings]

FIG. 1 schematically shows a phenomenon that occurs when a glass melt flows down from an outflow pipe made of Pt or a Pt alloy and that a part of the glass melt wets out of a tip portion of the outflow pipe. It is sectional drawing.

FIG. 2 is a side view for explaining a method of measuring a “contact angle” according to the present invention.

FIG. 3 is a sectional view schematically showing a precision press molding apparatus used in Example 31.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pt or Pt alloy outflow pipe, 2 ... Glass melt, 2a ... Glass melt wet out of the tip of the outflow pipe, 5 ... 95Pt-5Au alloy plate, 6a ... Before melting The glass sample of 6b ...
Glass sample melted and solidified, θ ... contact angle, 1
5. Material for precision press molding.

Claims (13)

(57) [Claims] 1. A refractive index (n _d ) containing silicon oxide and boron oxide of 1.7 or more, and an Abbe number (ν _d ) of 28 to 4
1. The optical glass according to 1, wherein the ratio of the content of silicon oxide to the content of boron oxide is greater than 0.78, and the contact angle with Pt or a Pt alloy at a predetermined temperature or a predetermined temperature region equal to or higher than the liquidus temperature. An optical glass characterized by being 40 ° or more and having a sag point T _s of 580 ° C. or less. 2. The optical glass according to claim 1, further comprising lithium oxide, calcium oxide, titanium oxide, and niobium oxide, in addition to silicon oxide and boron oxide. 3. Silicon oxide, boron oxide, lithium oxide
Of calcium oxide, calcium oxide, titanium oxide and niobium oxide
Amount is more than 63wt%, silicon oxide is 17 ~ 33wt%
(However, if it is 17 wt% or 33 wt%
Exclude each case. ), 1-25 wt% boron oxide, acid
5-11% by weight of lithium oxide and 5-27% of calcium oxide
wt% (except when it is 5 wt%), titanium oxide
1 to 20% by weight of lanthanum oxide, less than 0 to 16% by weight,
Contain 0-10wt% zirconium oxide
The optical glass according to claim 2, wherein: 4. A lanthanum oxide containing 2.5 to less than 16% by weight.
The optical glass according to claim 3, comprising: 5. It contains silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide in a total amount of at least 63 wt%, and the content of each of these components is 17 to 3 of silicon oxide.
3 wt% (excluding cases of 17 wt% and 33 wt%, respectively), 1 to 25 wt% of boron oxide
%, Lithium oxide 5 to 11 wt%, calcium oxide 5 to 2
7% by weight (excluding 5% by weight), 1 to 20% by weight of titanium oxide, 13 to 30% by weight of niobium oxide (excluding 13% by weight), and the silicon oxide and the oxidation The total amount of boron is 20-50 wt%, lanthanum oxide is less than 0-16 wt%, and zinc oxide is 0-12
wt%, 0-15 wt% barium oxide, 0-10 wt% zirconium oxide, 0-10 wt% strontium oxide,
0-6 wt% of tungsten oxide and 0 of aluminum oxide
0-7 wt%, sodium oxide 0-5 wt%, potassium oxide 0-5 wt%, yttrium oxide 0-5 wt%, gadolinium oxide 0-5 wt%, ytterbium oxide 0-5 wt%
wt%, 0-5 wt% tantalum oxide, 0-2 wt% arsenic oxide
%, And each containing antimony oxide 0-2 wt%, the optical glass according to any one of claims 1 to 4. 6. It contains silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide in a total amount of at least 63 wt%, and the content of each of these components is 17.5% of silicon oxide.
~ 31 wt%, boron oxide 1.5 ~ 22 wt%, lithium oxide 5.3 ~ 9.5 wt%, calcium oxide 5.5 ~ 24.
5 wt%, titanium oxide 2.5-18 wt%, niobium oxide 13
２７27.5 wt% (excluding the case of 13 wt%), and the total amount of the silicon oxide and the boron oxide is 24-43 wt%, and the content of the silicon oxide with respect to the content of the boron oxide Is greater than 0.80, lanthanum oxide is 0 to 15 wt%, and zinc oxide is 0 to 11 wt%
%, Barium oxide 0-12 wt%, zirconium oxide 0-7 wt%, strontium oxide 0-8 wt%, tungsten oxide 0-4 wt%, aluminum oxide 0-5 wt%
%, Sodium oxide 0 to 3 wt%, potassium oxide 0 to 0%
3 wt%, 0-3 wt% yttrium oxide, 0-3 wt% gadolinium oxide, 0-3 wt% ytterbium oxide,
The optical glass according to any one of claims 1 to 5 , comprising 0 to 3 wt% of tantalum oxide, 0 to 2 wt% of arsenic oxide, and 0 to 2 wt% of antimony oxide. 7. It contains silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide and niobium oxide in a total amount of at least 63 wt%, and the content of each of these components is 17 to 3 of silicon oxide.
3 wt% (excluding cases of 17 wt% and 33 wt%, respectively), 1 to 25 wt% of boron oxide
%, Lithium oxide 5 to 11 wt%, calcium oxide 5 to 2
7% by weight (except when it is 5% by weight), 1 to 20% by weight of titanium oxide, 13 to 30% by weight of niobium oxide (excluding the case of 13% by weight). The total amount of boron oxide is 20-50wt%
The ratio of the content of silicon oxide to the content of boron oxide is larger than 0.78, lanthanum oxide is 0 to less than 16 wt%, and zinc oxide is 0 to 12
wt%, 0-15 wt% barium oxide, 0-10 wt% zirconium oxide, 0-10 wt% strontium oxide,
0-6 wt% of tungsten oxide and 0 of aluminum oxide
0-7 wt%, sodium oxide 0-5 wt%, potassium oxide 0-5 wt%, yttrium oxide 0-5 wt%, gadolinium oxide 0-5 wt%, ytterbium oxide 0-5 wt%
wt%, 0-5 wt% tantalum oxide, 0-2 wt% arsenic oxide
%, And antimony oxide are contained in an amount of 0 to 2 wt%, respectively. A glass gob obtained by dropping a glass melt from which an optical glass is obtained from an outlet of an outflow pipe made of Pt or a Pt alloy is formed, and precision is obtained. A method for producing a material for precision press molding, characterized by obtaining a material for press molding. 8. Silicon oxide, boron oxide, lithium oxide
Containing calcium oxide, calcium oxide, titanium oxide and niobium oxide
The total amount of the components is 63% by weight or more;
Content of silicon oxide is 17 to 33 wt% (however, 1
7% by weight and 33% by weight respectively
except. ), 1-25 wt% boron oxide, 5-5 lithium oxide
11 wt%, calcium oxide 5-27 wt% (however, 5 wt%
Except when it is%. ), 1-20 wt% titanium oxide
And the total amount of the silicon oxide and the boron oxide is 20
Silicon oxide to boron oxide content at ~ 50 wt%
Is greater than 0.78, and lanthanum oxide
2.5 to less than 16 wt%, 0 to 10 wt% zirconium oxide
% Of the glass melt from which the optical glass is obtained.
Gas obtained by dropping from the outlet of a gold outflow pipe
Forming rasgob to obtain materials for precision press molding
A method for producing a material for precision press molding, characterized by the following . 9. The optical glass according to claim 1, wherein the content of each of silicon oxide, boron oxide, lithium oxide, calcium oxide, titanium oxide, and niobium oxide is 17.5 to silicon oxide.
31 wt%, boron oxide 1.5 to 22 wt%, lithium oxide 5.3 to 9.5 wt%, calcium oxide 5.5 to 24.5
wt%, titanium oxide 2.5-18 wt%, niobium oxide 13-
27.5wt% (except when it is 13wt%)
And the total amount of the silicon oxide and the boron oxide is 24-43 wt%, the ratio of the silicon oxide content to the boron oxide content is greater than 0.80, and lanthanum oxide is 0-15 wt%. 0-11wt zinc oxide
%, Barium oxide 0-12 wt%, zirconium oxide 0-7 wt%, strontium oxide 0-8 wt%, tungsten oxide 0-4 wt%, aluminum oxide 0-5 wt%
%, Sodium oxide 0 to 3 wt%, potassium oxide 0 to 0%
3 wt%, 0-3 wt% yttrium oxide, 0-3 wt% gadolinium oxide, 0-3 wt% ytterbium oxide,
The method according to claim 7 , wherein the optical glass contains 0 to 3 wt% of tantalum oxide, 0 to 2 wt% of arsenic oxide, and 0 to 2 wt% of antimony oxide. 10. The method of claim 1-6 material for precision press-molding, characterized by comprising the optical glass according to any one of. 11. shaping the glass gob obtained by causing dropped molten glass optical glass is obtained according to any one of claims 1 to 6 Pt metal or Pt outlet of alloy flow pipe, A method for producing a material for precision press molding, characterized by obtaining a material for precision press molding. 12. An optical product comprising the optical glass according to any one of claims 1 to 6 . 13. The method according to claim 7 , wherein the mold is provided with at least an upper mold and a lower mold as mold elements for forming a cavity having a predetermined shape. Placing the material for precision press molding, including the step of precision press molding the material for precision press molding into a predetermined shape using the mold under the condition that the material for precision press molding is softened by heating A method of manufacturing an optical product.