WO2006118130A1

WO2006118130A1 - Optical glass

Info

Publication number: WO2006118130A1
Application number: PCT/JP2006/308699
Authority: WO
Inventors: Umihiko Mori; Tatsuo Hidaka; Akio Konishi; Hideyuki Kuribayasi
Original assignee: Nihon Yamamura Glass Co., Ltd.
Priority date: 2005-04-27
Filing date: 2006-04-26
Publication date: 2006-11-09
Also published as: JP4560438B2; JP2006306648A

Abstract

Disclosed is an optical glass which is easily molded without adhering to a metal mold while having an improved devitrification resistance. The optical glass is characterized by containing 1-8% by weight of SiO2, 16-40% by weight of B2O3 (provided that the amount of B2O3 and SiO2 are 20-42% by weight in total), 0-4% by weight of Li2O, Na2O and K2O in total, 10-30% by weight of ZnO, 20-40% by weight of La2O3, 6.5-12% by weight of of Y2O3, 0-10% by weight of Gd2O3, 0.05-3% by weight of Yb2O3 (provided that the amount of Y2O3, La2O3, Yb2O3 and Gd2O3 are 25-50% by weight in total), 0-8% by weight of ZrO2 and 0-8% by weight of Ta2O5, and having a refractive index of 1.70-1.82 and an Abbe number of 40-55.

Description

Specification

Optical glass

[0001] The present invention relates to an optical glass. More specifically, the refractive index (n) is 1.70 to: L 82, Abbe

d

Number) 0 to 55, and has a composition suitable for molding, and has a resistance against devitrification d

Relates to an improved optical glass.

Background art

[0002] In recent years, aspherical lenses have come to be used in many cases while the small and light weight of optical devices has been remarkably advanced. This is because aspherical lenses can easily correct light aberrations, reduce the number of lenses, and make the device compact.

[0003] Aspherical lenses are manufactured by heating and softening a glass preform and precision molding press molding it into a desired shape. There are two main methods for obtaining preforms: one is to cut glass pieces into glass blocks or rods and process them into spheres, and the other is to use glass melt with the nozzle tip force. This is a method of dropping to obtain a spherical glass preform.

[0004] In order to obtain a glass molded article by precision mold press molding, it is necessary to perform pressure molding of the preform at a temperature equal to or higher than the yield point (At). For this reason, the higher the yield point (At) of the preform, the higher the temperature of the mold in contact with it, and the easier it is for the surface of the mold to be consumed by acid and so on. Cannot be realized. For this reason, it is desired that the optical glass constituting the preform can be molded at a relatively low temperature, and therefore the glass transition point (Tg) and Z or the yield point (At) are low.

[0005] In addition, at a temperature equal to or higher than the yield point (At), the mold surface in contact with the preform may be denatured by reacting with the preform and become adherent during molding. Although most of the mold surface in contact with the preform can be prevented from sticking by pretreatment with a mold release agent, the sliding surfaces of the partial molds cannot be treated with the mold release agent, and the sliding surface is not yet open. It remains in the process. For this reason, adhesion occurs between the press-molded glass in the mold and the sliding surface in contact with the glass, and this extremely reduces productivity and makes mass production impossible. It will be a function.

[0006] Optical glasses used for aspherical lenses are required to have various optical constants, but in particular, those having a high refractive index and a high Abbe number (low dispersion) are strongly required. (See Patent Documents 1, 2, and 3). Conventionally, lanthanum borate is a typical glass having such an optical constant. However, in general, lanthanum borate glasses with a low glass transition point (Tg) and yield point (At) have a problem of poor devitrification, that is, they tend to lose transparency. In the preform manufacturing process, there was a problem that it was often devitrified and clouded. Further, these glasses have a problem that even if the devitrification property can be improved, there is a problem that the surface of the mold is easily modified to be adhesive, and the moldability is inferior.

Patent Document 1: Japanese Patent Laid-Open No. 60-221338

Patent Document 2: Japanese Unexamined Patent Application Publication No. 2004-161506

Patent Document 3: Japanese Patent Laid-Open No. 2002-173334

Disclosure of the invention

Problems to be solved by the invention

[0007] The present invention improves various disadvantages found in the above-mentioned optical glass, and has a desirable optical constant of 1.70 to: a refractive index (n) of L 82 and 40

d Abbe number of ~ 55 (V

It is an object of the present invention to provide an optical glass having d) which is easy to mold, does not adhere to a mold during molding, and has improved devitrification.

Means for solving the problem

[0008] As a result of repeated studies to achieve the above object, the present inventors have obtained the above-described desirable optical constant, excellent anti-devitrification property, and gold by setting the composition within a specific range. The inventors have found that an optical glass can be obtained that exhibits excellent moldability by preventing the adhesion of the mold surface and has a low bending yield point (At), and has completed the present invention.

That is, the present invention provides the following.

(1) Optical glass, the following components:

SiO... 1 to 8% by weight,

2

BO ··· 16 to 40% by weight (However, BO + SiO · · · 20-42 weight ⁰ /.),

2 3 2

LiO + NaO + KO — 0-4% by weight,

2 2 2

ZnO ', '10 -30% by weight,

La O—20-40% by weight,

twenty three

YO · '· 6.5~12 weight ^_0/0,

twenty three

GdO — 0-10% by weight,

twenty three

Yb O ... (). 05-3wt%

twenty three

(However, YO + La O + Yb O + GdO · · · 25~50 weight ^_0/0),

2 3 2 3 2 3 2 3

ZrO ',' 0-8 wt%, and

2

Ta O '' '0-8 wt%,

twenty five

The refractive index (n) is 1.70-1.82 and the Abbe number (V) is 0 to 55.

Optical glass, which is a feature.

(2) The following ingredients:

MgO ··· () ~: L0 weight ^_0/0,

CaO ··· () ~ 10 weight ^_0/0,

SrO ··· () ~ 10 weight ^_0/0,

BaO ··· () ~ 10 weight ^_0/0,

NbO "'0-8% by weight, and

twenty five

WO ··· ^{0 to} 3.5 weight ⁰

Three

The optical glass of 1 above, further comprising

(3) Optical glass, the following components:

SiO ··· 1 to 6% by weight,

2

BO ', '16 -40% by weight,

twenty three

GeO '.' 0 ~ 3wt%

2

(However, BO + SiO ··· 22~42 weight ^_0/0),

2 3 2

Li O + Na O + K · ··· 0.5-4 weight ⁰ /. ,

2 2 2

ZnO ', '11 -28 wt%,

La Ο —20-38% by weight, YO · '· 6.5~: L1 weight ^_0/0,

twenty three

GdO ',' 1-10% by weight,

twenty three

Yb O --- 0.05-3wt%

twenty three

(However, YO + La Ο + Yb Ο + Gd Ο · · · 25~48 weight ^_0/0),

2 3 2 3 2 3 2 3

ZrO '' '0-6 wt%,

2

Ta O '' '0-8 wt%,

twenty five

MgO '.' 0-8% by weight,

CaO '.' 0-8% by weight,

SrO '.' 0-8% by weight,

BaO '.' 0-8% by weight,

NbO "'0-8% by weight, and

twenty five

WO · '· 0~3.5 weight ^_0/0,

Three

The refractive index (η) is 1.70-1.82 and the Abbe number (V) is 0 to 55.

Optical glass, which is a feature.

(4) The optical glass as described in any one of 1 to 3 above, which has a glass transition point (Tg) of 510 to 570 ° C.

(5) The optical glass as described in any one of 1 to 4 above, which has a yield point (At) force of 50 to 610 ° C.

The invention's effect

[0010] According to the present invention having the above-described compositions, 1.70 to: a refractive index (n) of L 82 and 40 to 55

Tube number (V)

It is possible to obtain an optical glass which has d, is easy to mold, does not cause adhesion to the mold during molding, and has improved devitrification.

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, the refractive index (n) is the refractive index d at 587.56 nm given by helium.

Say.

In the present invention, the Abbe number (V) is defined by V = (n-l) / (n-n), and this d d d F C

Where n is the refractive index at 486.13 nm given by hydrogen and n is given by 656.2

F C

Refractive index at 7nm. A large Abbe number means that the wavelength dependence of the refractive index is low ( That is, dispersion is low), and chromatic aberration is suppressed.

[0012] In addition, the yield point (At) is the maximum point at which the expansion curve turns upward and downward due to the softness of the glass when the thermal expansion is measured with a thermomechanical analyzer (TMA). When the temperature.

In the composition of the optical glass of the present invention, SiO is a glass network structure forming component, and

2

It is an essential component for giving the glass a stable manufacturable stability. In order to obtain a remarkable stabilization effect, the SiO content is preferably 1% by weight or more, more preferably 2% by weight or more.

2

Preferred 2. More preferably 5% by weight or more. In order to obtain a high refractive index as an optical glass, the SiO content is preferably 8% by weight or less, and preferably 6% by weight or less.

2

More preferably, it is more preferably 5.5% by weight or less.

[0014] B 2 O is also a glass network structure-forming component, and has high resistance to devitrification in the optical glass of the present invention.

twenty three

It is an essential component for providing stability. B O for high stability

2 3 content is

16% by weight or more is preferable. 18% by weight or more is more preferable. In order to obtain a high refractive index as an optical glass, the content of B 2 O should be 40% by weight or less.

twenty three

It is more preferably 38% by weight or less.

[0015] However, in order to prevent devitrification and stably produce a transparent optical glass even within the above range, the total content of SiO and BO should be 20% by weight or more. 22%

2 2 3

More preferably. On the other hand, for high refractive index, the total content of SiO and B 2 O is included.

2 2 3 The content is preferably 42% by weight or less, more preferably 40% by weight or less.

[0016] Li 0, Na 2 O and Κ Ο are not essential components, but their content is 0% by weight.

2 2 2

Although it is good, it is an effective component for remarkably lowering the glass transition point and the yield point, and both can be interchanged with each other at an equivalent content. When added, these components can be added to a total of, for example, 0.5% by weight or more. On the other hand, in order not to lower the stability of the glass, it is preferable to keep the content of these components (the total of two or more of them) within 4% by weight. More preferably, it is as follows.

[0017] ΖηΟ is an essential component that lowers the glass transition point and yield point, and at the same time contributes to the stability of the glass. In order to achieve a sufficiently low yield point, the content of ΖηΟ is preferably 10% by weight or more, more preferably 11% by weight or more. On the other hand, of glass In order to achieve stability and an excellent optical constant, the content of ZnO is preferably 30% by weight or less, more preferably 28% by weight or less.

[0018] La O is a component that contributes to an improvement in both the refractive index and the Abbe number. Refractive index and Abbe

twenty three

In order to obtain a sufficient improvement in the number, it is preferable that the content of La O is 20% by weight or more.

twenty three

More preferably, the content is 22% by weight or more. On the other hand, excessive inclusion increases the tendency to devitrification. To prevent this, it is preferable that the content of La O be 40% by weight or less.

twenty three

More preferably, it is 8% by weight or less.

[0019] Y O, like La O, is a component that contributes to an improvement in both the refractive index number and the Abbe number.

2 3 2 3

The As a result of examination, to obtain these effects sufficiently for the purpose of the present invention, Y

It has been found that the content of 2 o 3 should be 6.5% by weight or more. However, excessive content increases the tendency of glass to devitrify. To prevent this, the content of Y 2 O is 12% by weight.

twenty three

The content is preferably 11% by weight or less, and more preferably 10% by weight or less.

[0020] Gd O is not an essential component, but its content may be 0% by weight.

Like 2 3 2 3, it is a component that contributes to an improvement in both the refractive index number and the Abbe number. For example, it is more preferably contained at 1.0% by weight. However, excessive content increases the tendency of glass to devitrify. To prevent this, the Gd O content is preferably 10% by weight or less.

twenty three

More preferably, it is more preferably 5% by weight or less.

[0021] YbO, like LaO, is a component that contributes to improving both the refractive index number and the Abbe number.

2 3 2 3

is there. As a result of the study, in order to obtain these effects sufficiently for the purpose of the present invention, Yb

2 o 3

It has been found that it is extremely preferable to contain 0.05% by weight or more. On the other hand, excessive content increases the tendency of glass to devitrify. To prevent this, the YbO content should be less than 3% by weight.

twenty three

2% by weight or less is preferable, and 1% by weight or less is more preferable.

[0022] In addition, using two or more of La 2 O, Y 2 O, Gd 2 O, and Yb 2 in combination improves the refractive index.

2 3 2 3 2 3 2 3

It is advantageous to increase the stability of the glass against devitrification. In order to achieve the objective high refractive index of the present invention, the total amount thereof is preferably 25% by weight or more, more preferably 27% by weight or more, and more preferably 30% by weight or more. Is more preferred Yes. On the other hand, in order not to reduce the stability of the resulting glass, their total amount is

It is preferably 50% by weight or less, more preferably 48% by weight or less, and still more preferably 46% by weight or less.

[0023] ZrO is not an essential component and its content may be 0% by weight!

2

Since it contributes to the improvement of devitrification and has the effect of increasing the refractive index, the content is more preferably, for example, 1% by weight or more, more preferably 2% by weight or more. On the other hand, in order not to decrease the stability of the glass due to excessive ZrO content,

2 2 The content is preferably 8% by weight or less, more preferably 6% by weight or less, and even more preferably 5% by weight or less.

[0024] Ta O is not an essential component, but its content may be 0% by weight.

twenty five

For example, the content is more preferably 1% by weight or more, and more preferably 2% by weight. On the other hand, in order not to cause an increase in dispersion and a decrease in the Abbe number V due to an excessive content, the d 2 5 content of Ta O should be 8% by weight or less, and 7.5% by weight or less. More preferable.

[0025] GeO is not an essential component, and its content may be 0% by weight.

2 2 and B O

As in 23, the glass network structure-forming component has the effect of maintaining the stability that can be produced in glass, and is more advantageous than SiO and B 2 O in achieving a high refractive index. Therefore

2 2 3

The GeO content is more preferably 0.5% by weight or more, for example, 1% by weight or more.

2

More preferably. However, it is expensive and from an economically effective point of view, the GeO content is

2

3% by weight or less is preferable.

[0026] MgO, CaO, SrO and BaO are not essential, but are all components contributing to the stability of the glass. Each content is preferably 0 to 10% by weight. In addition, when two or more of these components are contained, the total content thereof is preferably 0 to 10% by weight.

[0027] WO is not an essential component but its content may be 0% by weight.

Three

It is a component that contributes to stability against devitrification of laths. However, this component may oxidize the mold surface by changing to w ⁶⁺ force w ^5+. Preferred 3% by weight or less is more preferred 2 More preferably, it is not more than% by weight.

[0028] The content of NbO, which is not an essential component, may be 0% by weight.

twenty five

It is a component that contributes to stability. In addition, Nb O is a part or all of the WO.

2 5 3

It is also a component that can be substituted to replace the action of WO. If excessively contained, reverse

Three

In order to prevent the glass from devitrifying, the NbO content must be 8% by weight or less.

twenty five

More preferably, it is 6% by weight or less, and more preferably 4% by weight or less.

[0029] As a raw material for producing the optical glass of the present invention, for example, for BO, HBO, B

2 3 3 3 2 o, etc. can be used, and other ingredients can be used as raw materials such as various oxides, carbonates, and glass.

Three

Usual optical glass materials such as acid salts can be used. The raw materials for production are mixed at a ratio that achieves the oxide composition in the above-mentioned predetermined range, the mixture is melted at 1100 to 1250 ° C, homogenized through the steps of clarification (degassing) and stirring, The optical glass of the present invention, which is colorless, has a high refractive index, has a high Abbe number, is transparent, is homogeneous, and has excellent workability, can be obtained by lowering the temperature to 950 to 1050 ° C. and pouring into a mold. it can.

Example

Hereinafter, the present invention will be described more specifically with reference to examples. However, it is not intended that the present invention be limited to these examples.

[0031] The composition of the optical glasses of the examples and comparative examples shown in Table 1 and the measurement of the refractive index (n), Abbe number (V), yield point (At), and glass transition point were performed. went. Compare here d d

Example 1 is the same composition as the glass described in Example 36 of Patent Document 1, Comparative Example 2 is the same composition as the glass described in Example 7 of Patent Document 2, and Comparative Example 3 is a patent document. 3. It has the same composition as the glass described in Example 3.

[0032] The refractive index (n) and the Abbe number (V) are measured using a refractometer (KPR-200d d

).

The glass transition point (Tg) and yield point (At) are measured by heating and heating a rod-shaped sample with a length of 15 to 20 mm and a diameter of 3 to 4 mm at a constant rate of 5 ° C / min. Was obtained from the thermal expansion curve obtained by measuring.

The measurement results are shown in the lower part of the table. [table 1]

As can be seen in Table 1, all the glasses of the examples of the present invention have a refractive index (n) of 1.70 to L

d

82, Abbe number (V) force 0 55, sufficient optical constant as optical glass

d

. In addition, devitrification that does not adhere to the mold surface during molding was also strong. Therefore, it has suitable properties to enable mass production. Furthermore, in both cases, the glass transition point (Tg) is in a relatively low temperature range of 510 570 ° C and At is 550 610 ° C. Easy to shape. The glass of the examples is suitable for both the formation of a spherical preform by dripping and the precision mold press because it is excellent in devitrification.

On the other hand, in Comparative Examples 1 to 3, the refractive index (n) is 1.70-1.82 and Abbe d

Although the number (V) force is in the range of 0 to 55, it is the same as the example, but d in Comparative Example 1

It has been confirmed that devitrification occurs in glass, and the glass of Comparative Example 2 has a yield point (At) and a glass transition point (Tg) that are very high compared to the glass of Example, and can be molded by a normal apparatus. In Comparative Example 3, it was extremely difficult to crystallize and glass could not be formed. Therefore, it was impossible to measure the refractive index and the Abbe number. The numerical values of the refractive index and Abbe number of Comparative Example 3 described in the table are described in Patent Document 3 as the numerical values of the glass of Example 3, and are reprinted. As shown by the results of these comparative examples, these comparative examples were not suitable for efficiently forming a spherical preform by dropping or precision mold press molding.

Industrial applicability

[0036] According to the present invention, 1. 70 ~: optical glass having a refractive index (n) of L 82 and an dd of 40 to 55 having an Abbe number (V), a sufficient optical constant, is stably mass-produced. can do. In addition, mold molding is easy, it does not cause adhesion to the mold during molding, and has excellent devitrification properties.

Since it is suitable for mass production and can keep the glass transition point (Tg) and yield point (At) low, it is possible to provide optical glass with particularly high mass production efficiency.

Claims

The scope of the claims

An optical glass having the following components:

SiO ··· 1 to 8% by weight,

2

BO ··· 16 to 40% by weight

twenty three

(However, BO + SiO · · · 20-42 weight ⁰ /.),

2 3 2

LiO + NaO + KO — 0-4% by weight,

2 2 2

ZnO ', '10 -30% by weight,

La O—20-40% by weight,

twenty three

YO --- 6.5~12 weight ^_0/0,

twenty three

GdO — 0-10% by weight,

twenty three

Yb O --- 0.05-3wt%

twenty three

(However, YO + La O + Yb O + GdO · · · 25~50 weight ^_0/0),

2 3 2 3 2 3 2 3

ZrO ',' 0-8 wt%, and

2

Ta O '' '0-8 wt%,

twenty five

The refractive index (n) is 1.70-1.82 and the Abbe number (V) is 0 to 55.

Optical glass, which is a feature.

The following ingredients,

MgO ··· () ~: L0 weight ^_0/0,

CaO ··· () ~ 10 weight ^_0/0,

SrO ··· () ~ 10 weight ^_0/0,

BaO ··· () ~ 10 weight ^_0/0,

NbO "'0-8% by weight, and

twenty five

WO ··· ^{0 to} 3.5 weight ⁰

Three

The optical glass of claim 1, further comprising:

An optical glass having the following components:

SiO ··· 1 to 6% by weight,

2

BO ', '16 -40% by weight,

twenty three

GeO '.' 0 ~ 3wt% (However, BO + SiO 22-42 weight ⁰ / o),

2 3 2

Li O + Na O + KO · · · 0.5-4 weight ⁰ /. ,

2 2 2

ZnO ', '11 -28 wt%,

La O—20-38% by weight,

twenty three

YO · '· 6.5~: LI weight ^_0/0,

twenty three

GdO ',' 1-10% by weight,

twenty three

Yb O --- 0.05-3wt%

twenty three

(However, Y Ο + La Ο + Yb Ο + Gd Ο · · · 25~48 weight ^_0/0),

2 3 2 3 2 3 2 3

ZrO '' '0-6 wt%,

2

Ta O '' '0-8 wt%,

twenty five

MgO '.' 0-8% by weight,

CaO '.' 0-8% by weight,

SrO '' '0-8 wt%,

BaO '.' 0-8% by weight,

NbO "'0-8% by weight, and

twenty five

WO · '· 0~3.5 weight ^_0/0,

Three

The refractive index (η) is 1.70-1.82 and the Abbe number (V) is 0 to 55.

Optical glass, which is a feature.

4. The optical glass according to claim 1, wherein the glass transition point (Tg) is 510 to 570 ° C.

The optical glass according to any one of claims 1 to 4, wherein a yield point (At) is 550 to 610 ° C.