JP5491686B2 - Glass - Google Patents

Description

  The present invention relates to an ultra-low refractive index ultra-low dispersion glass having a refractive index (nd) of 1.41 to 1.47 and an Abbe number (νd) of 90 to 100, a lens obtained using this glass, With regard to an optical element such as a prism, in particular, a raw material composition that effectively suppresses devitrification (crystal) generated when cooled from a molten state, which is a problem during glass production, requires highly accurate chromatic aberration characteristics. The present invention relates to a glass material suitable for a projection lens and a prism of an optical device typified by a camera or a projector, an optical element produced therefrom, and an optical device.

Low refractive index and low dispersion optical materials are characterized by small changes in refractive index (dispersion) due to the wavelength of light, and are suitable for lenses and prisms of optical devices that require high-accuracy chromatic aberration characteristics. The material calcium fluoride crystal (CaF ₂ ) was used, but it is difficult to produce a homogeneous and large crystal, and it is necessary to pay close attention to the processing of the crystal. Glass materials that are excellent in workability and chemical durability are frequently used. As glass materials, Patent Documents 1 to 3 disclose various glass compositions and preparation compositions.

  In order to realize low refractive index and low dispersion characteristics with a glass material, it is necessary to introduce a large amount of anion components (typically fluorine components) other than oxygen ions into the glass, but glass containing a large amount of fluorine components. Is inferior in devitrification resistance, causing devitrification in the process of cooling the glass melt, making it difficult to obtain a stable and large amount of homogeneous glass material, which is one of the factors hindering economic production activities. there were.

  In Patent Documents 1 and 3, improvement studies on the devitrification resistance of glass are performed, but in them, only the improvement of devitrification in a short time of keeping the temperature around the glass forming temperature for about 1 to 2 hours is considered. However, the long-term devitrification resistance applicable to a highly economical continuous melt molding production system has not been considered sufficient.

  Patent Document 4 discloses a method for producing a fluoride phosphate optical glass for the purpose of suppressing devitrification and formation of striae, but obtains a large glass material with a high glass melt casting temperature. Attempts to form in a low-viscosity region make it impossible to strictly control the glass flow rate, and as a result, there is a concern that streaky non-uniform portions (streaks) may occur due to the flow of glass melt. Due to the properties of glassy materials with low thermal conductivity, the inside of the glass is harder to cool than the surface, and as a result, the time of exposure to the temperature at which devitrification occurs increases, and devitrification occurs inside the glass. It could not be said that it was improved enough.

JP-A-60-210545 JP 63-144141 A Japanese Patent Laid-Open No. 06-191876 JP 09-142875 A

  The object of the present invention is to obtain a refractive index (nd) of 1.41 to 1.47 and an Abbe number (νd) that can be stably obtained by a general melting method under the circumstances of the prior art. An object of the present invention is to provide an ultra-low refractive index ultra-low dispersion fluorophosphate glass having a refractive index of 90-100.

  As a result of intensive studies and research in order to achieve the above-mentioned goals, the present inventors made Si and / or B contain less than 0.005 to 0.2 element mass% in the glass raw material composition, and P, Al, By adjusting the component ratios of Ca, Sr, Ba, Y, F, and O, devitrification (crystal) generation inside the glass during the cooling process from the molten state while realizing the desired refractive index and Abbe number. It discovered that the said objective could be achieved by suppressing effectively, and came to make this invention. The configuration is shown below.

(Configuration 1)
Glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, wherein P is 0.1 to 5.0%, Al 1.0 to 20.0%, F 30.0 to 60.0%, O 1.0 to 20.0%, and one or more of Ca, Sr and Ba are essential. And an optical constant having a refractive index (nd) of 1.41-1.47 and an Abbe number (νd) of 90-100.
(Configuration 2)
Glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, wherein P is 0.1 to 5.0%, Al 1.0-20.0%, Ca 3.0-20.0%, Sr 1.0-20.0%, Ba 1.0-2
0.0%, F 30.0-60.0%, O 1.0-20.0%, Mg 0-10.0%, Y 0-10.0%, nd) is a glass having an optical constant of 1.41-1.47 and an Abbe number (νd) of 90-100.
(Configuration 3)
Glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, wherein P is 1.0 to 5.0%, Al 8.0 to 18.0%, Ca 3.0 to 18.0%, Sr 3.0 to 19.0%, Ba 3.0 to 1
8.0%, F 32.0-58.0%, O 1.0-18.0%, Mg 0.3-8.0
% And Y from 0.1 to 8.0% and La from 0 to 5.0% and / or Gd from 0 to 5.0% and / or Li from 0 to 3.0% and / or Na from 0 -3.0% and / or K contains 0-3.0%, and has an optical constant in the range of refractive index (nd) of 1.42-1.46 and Abbe number (νd) of 92-98. Glass.
(Configuration 4)
The glass according to any one of configurations 1 to 3, wherein the element mass% ratio (Si + B + P + Al) / F is in the range of 0.15 to 0.40.
(Configuration 5)
It is glass as described in any one of the structures 1-3, Comprising: Element mass% ratio (Si + B + P + Al) / F is 0.20-0.35, and element mass% ratio Ba / Sr is 0.6-1. Glass in the range of 0.0.
(Configuration 6)
A glass having an optical constant having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98,
Based on the total mass of the glass raw material,
Less than 0.005% to 0.2% of Si and / or B is introduced from the raw materials except the oxide,
1.0 to 5.0% of P introduced from the phosphoric acid compound raw material,
3.0 to 20.0% of Al introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
Mg introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride is 0.0 to 5.
0%,
3.0 to 20.0% of Ca introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
3.0 to 20.0% of Sr introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
3.0 to 20.0% of Ba introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
0.01 to less than 8.0% of Y introduced from the raw material essentially containing fluoride,
0.0 to 5.0% of La introduced from a raw material essentially containing fluoride,
0.0 to 5.0% of Gd introduced from a raw material essentially containing fluoride,
0.0 to 3.0% of Li introduced from a raw material essentially containing fluoride,
0.0 to 3.0% of Na introduced from the raw material containing the fluoride essential,
0.0 to 3.0% of K introduced from a raw material essentially containing fluoride,
35 to 65% of F introduced from a raw material essentially containing fluoride,
0.0 to 3.0% of Cl introduced from the chloride raw material,
0.0 to 5.0% of Br introduced from bromide raw material,
0.0 to 5.0% of I introduced from the iodide raw material,
0.1 to 10% of O introduced from phosphoric acid compound raw material and oxide raw material
A glass obtained by melting a glass raw material composition characterized by containing.
(Configuration 7)
Element mass%
Si and / or B introduced from the raw material excluding oxide is 0.005 to less than 0.2%,
1.0 to 5.0% of P introduced from the phosphoric acid compound raw material,
8.0 to 18.0% of Al introduced from the phosphoric acid compound raw material and / or fluoride raw material,
0.3 to 3.0% of Mg introduced from the phosphoric acid compound raw material and / or fluoride raw material,
7.0 to 15.0% of Ca introduced from the phosphoric acid compound raw material and / or fluoride raw material,
11.0 to 18.0% of Sr introduced from the phosphoric acid compound raw material and / or fluoride raw material,
Ba introduced from the phosphoric acid compound raw material and / or fluoride raw material is 5.0 to 15.0%,
However, the mass% sum (Sr + Ba) is 20.0-35.0%,
0.5 to less than 6% of Y introduced from the fluoride raw material,
0.0 to 4.0% La introduced from the fluoride raw material,
0.0 to 4.0% of Gd introduced from the fluoride raw material,
0.0 to 2.0% of Li introduced from the fluoride raw material,
0.0 to 2.0% of Na introduced from the fluoride raw material,
0.0 to 1.0% of K introduced from the fluoride raw material,
40 to 55% of F introduced from the fluoride raw material,
0.0 to 1.0% of Cl introduced from the chloride raw material,
0.0 to 1.0% of Br introduced from bromide raw material,
0.0 to 1.0% of I introduced from the iodide raw material,
0.5 to 8% of O introduced from phosphoric acid compound raw material and oxide raw material
The glass according to Configuration 6, which is obtained by melting a glass raw material composition characterized by containing.
(Configuration 8)
Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.0 to 10.0%,
20-35% AlF ₃
CaF ₂ 15-25%,
15 to 28% of SrF ₂
BaF ₂ 5-20%,
0.1 to 10.0% of YF ₃
Melting a glass raw material composition containing less than 0.005 to 0.2% of Si and / or B introduced from the raw material excluding oxides in elemental mass%. Glass having an optical constant having a refractive index (nd) of 1.41 to 1.47 and an Abbe number (νd) of 90 to 100.
(Configuration 9)
Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.0 to 10.0%,
20-35% AlF ₃
CaF ₂ 15-25%,
15 to 28% of SrF ₂
BaF ₂ 5-20%,
0.1 to 10.0% of YF ₃
Melting a glass raw material composition containing less than 0.005 to 0.2% of Si and / or B introduced from the raw material excluding oxides in elemental mass%. Glass as described in any one of the structures 1-7 obtained by this.
(Configuration 10)
Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.5 to 10.0%,
AlF ₃ and 22 to 33 percent,
₁ to 7.0% MgF ₂
16-24% CaF ₂
However, the mass% ratio (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) is less than 0.77, and SrF ₂ is 15.5 to 27%.
BaF ₂ 6-18%,
YF ₃ 0.5-9.0%,
A glass raw material composition containing less than 0.005 to 0.2% of Si and / or B introduced from a raw material excluding oxides in elemental mass%. The glass of the structure 8 or the structure 9 obtained by fuse | melting a thing.
(Configuration 11)
A glass according to any one of configurations _{1~10, SiO 2, B 2 O} 3, Ba (PO 3) 2, BaCl 2, LiF, NaF, KF, and LiPF _6, NaPF _6, KPF ₆ A glass obtained by melting a glass raw material composition which is not contained.
(Configuration 12)
Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.5 to 10.0%,
AlF ₃ and 22 to 33 percent,
₁ to 7.0% MgF ₂
16-24% CaF ₂
However, the mass% ratio (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) is less than 0.73, and SrF ₂ is 15.5 to 27%.
BaF ₂ is less than 6-18%,
YF ₃ 0.5-9.0%,
Na ₂ SiF ₆ 0.0-3.0%,
The K ₂ SiF ₆ 0.0~3.0%,
However, the mass sum (Na ₂ SiF ₆ + K ₂ SiF ₆ ) is 0.01 to 5.0%,
0.1 to 3.0% of KHF ₂ ,
NH ₄ F · HF is 0.0 to 1.0%
Melting glass raw material composition characterized by containing SiO ₂ , B ₂ O ₃ , Ba (PO ₃ ) ₂ , BaCl ₂ , LiF, NaF, KF, LiPF ₆ , NaPF ₆ , KPF ₆ Glass having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98.
(Configuration 13)
It is glass as described in any one of the structures 6-12, Comprising: By element mass% on the basis of the total mass of a glass raw material, (Si + B + P + Al) / F is adjusted in the range of 0.20-0.40. A glass obtained by melting a glass raw material composition.
(Configuration 14)
It is glass as described in any one of composition 6-12, Comprising: It is element mass% on the basis of the total mass of a glass raw material, (Si + B + P + Al) / F is 0.27-0.30, and Ba / Sr Is obtained by melting a glass raw material composition characterized by being adjusted to a range of 0.6 to 1.0.
(Configuration 15)
The glass according to any one of the constitutions 1 to 14, wherein the glass is devitrified (crystal) even if it is kept at 690 ° C. for 60 hours after being cooled to 690 ° C. after being melted at 1000 ° C. Glass characterized by not generating.
(Configuration 16)
It is glass as described in any one of the structures 1-15, Comprising: The devitrification temperature (Tx) calculated from the devitrification loss temperature (Tm) in the temperature rising process in DTA measurement, and the heat generation start temperature in the temperature decreasing process The difference in glass is 15 ° C. or more.
(Configuration 17)
The glass according to any one of Structures 1 to 16, wherein the acid resistance of the glass measured by the Japan Optical Glass Industry Association Standard JOGIS06-1999 “Measurement Method of Chemical Durability of Optical Glass (Powder Method)” Glass characterized by being of grades 1 to 3.
(Configuration 18)
The optical element which uses as a base material the glass as described in any one of the structures 1-17.
(Configuration 19)
Reheat press working optical elements to create a glass according to any one of configurations 1 to 17.
(Configuration 20)
An optical apparatus using the optical element according to Configuration 18 or Configuration 19 .

The optical glass having configurations 1 to 3 according to the present invention will be described. In composition 1-5, the element mass% notation of each component displays each component contained in the glass finally produced by melting the raw material by mass% for each element.
The glass of constitution 1 is a glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, and P is 0.1 to 0.1%. 5.0%, Al is 1.0 to 20.0%, F is 30.0 to 60.0%, O is 1.0 to 20.0%, and one of Ca, Sr, and Ba It contains at least seeds and has an optical constant having a refractive index (nd) of 1.41 to 1.47 and an Abbe number (νd) of 90 to 100.

  In order to realize a low refractive index and low dispersion characteristics, it is necessary to introduce a large amount of F into the glass component. In order to form the glass skeleton with P, Al, F, and O, these are essential constituent elements. It is. Moreover, when there are too few P, Al, F, and O, the sum total of a glass modification element will increase too much with respect to the sum total of a glass skeleton formation element, and it will become difficult to form a stable glass skeleton.

  The effects and preferred contents of the individual elements will be described. P is an ingredient that has the effect of improving the mechanical properties of glass and the effect of making it difficult to break during processing such as cutting and polishing. If the amount of P is too small, not only is it difficult to form a stable glass skeleton, but it is also difficult to obtain the above-mentioned effects sufficiently. Therefore, preferably 0.1% or more, more preferably 0.5% or more, and most preferably Is 1.0% or more. On the other hand, if the amount of P is too much, the glass skeleton is stabilized, but the refractive index and dispersion are likely to be large, and it is difficult to realize a desired low refractive index and low dispersion characteristic. More preferably, it is 4.8% or less, and most preferably 4.5% or less.

  In the glass of the present invention, Al is a main glass skeleton-forming component. In addition to the effect of improving the mechanical properties of the glass, the average linear expansion coefficient (α) of the glass is reduced, and the chemical durability of the glass is improved. It becomes easy to obtain the effect to improve. If the amount of Al is too small, not only will it be difficult to form a stable glass skeleton, but it will also be difficult to obtain the above-mentioned effects sufficiently, so it is preferably 1.0% or more, more preferably 3.0% or more, most preferably 8 0.0% or more. On the other hand, if there is too much Al, the glass is not only easily broken, but devitrification is likely to occur in the cooling process from the melt, so it is preferably 20.0% or less, more preferably 19. 0% or less, most preferably 18.0% or less.

  In addition to being a glass skeleton-forming component, F has the effect of reducing the refractive index and dispersion in the glass of the present invention. If F is too small, the refractive index and dispersion tend to increase, making it difficult to achieve the desired optical characteristics. Therefore, it is preferably 30.0% or more, more preferably 32.0% or more, and most preferably 35.0%. That's it. On the other hand, if there is too much F, the ionic bondability in the glass will increase, and devitrification of the ionic bond crystal will likely occur in the cooling process from the melt, so it is preferably 60.0% or less, more preferably It is 58.0% or less, and most preferably 55.0% or less.

  O is a glass skeleton-forming component in the glass of the present invention, and has the effect of improving the mechanical properties of the glass and the effect of adjusting the refractive index. If the amount of O is too small, it is difficult to obtain the above-mentioned effects. Therefore, it is preferably 1.0% or more, more preferably 1.2% or more, and most preferably 1.5% or more. On the other hand, too much O not only makes it difficult to achieve the desired refractive index, but also increases the covalent bondability in the glass and causes devitrification of oxide crystals with a high melting point during the cooling from the melt. Since it becomes easy, it is preferably 20.0% or less, more preferably 18.0% or less, and most preferably 15.0% or less.

  In addition to the glass skeleton-forming component, at least one of Ca, Sr, and Ba is included as a glass modifying component in order to stably obtain the glass while realizing desired low refractive index and low dispersion characteristics. Is preferred. The glass modifying component is easy to obtain the effect of improving the devitrification resistance and the effect of adjusting the refractive index and dispersion by making the glass component multicomponent, and the elements that can obtain the effect are limited to Ca, Sr, and Ba. Although not necessarily, in order to stably obtain the low refractive index and low dispersion glass of the present invention, it is effective to introduce a cation element having a relatively large ion radius such as Ca, Sr, or Ba. Preferably, one or more of Ca, Sr, and Ba, more preferably two or more of Ca, Sr, and Ba, and most preferably, Ca, Sr, and Ba are essential.

  The inclusion of Si and / or B in the glass raw material composition is an important and indispensable element for suppressing the occurrence of devitrification (crystal) inside the glass during the cooling process from the molten state. In order to realize a low refractive index and a low dispersion characteristic, it is necessary to introduce a large amount of F into the glass component, and such intermolecular bonds of glass have stronger ionic bonds than covalent bonds. In the component component type and the composition ratio, in the process of cooling the glass melt, it becomes easy to change to an ionic crystal state that is more thermodynamically stable than maintaining the glass state. Therefore, in such a case, it is very difficult to improve the devitrification resistance of the glass while realizing the desired low refractive index and low dispersion properties by adjusting the glass constituent components. The essential constituents mentioned above, except for P and Al, have many elements with relatively large ionic radii, and by introducing Si and / or B with relatively small ionic radii into the glass appropriately, the glass structure of the main constituents It is possible to effectively inhibit the change from the glass state to the crystal state without significantly deforming the film. In order to sufficiently obtain this effect, the glass raw material composition preferably contains Si and / or B in a total amount of 0.005% or more, more preferably 0.008% or more, and most preferably 0.01. % Or more. On the other hand, if Si and / or B is contained in a large amount in the glass raw material composition, since Si and / or B has strong covalent bond, not only the covalent bond crystal is likely to precipitate, but also low It becomes difficult to realize low refractive index dispersion characteristics. Preferably, it is less than 0.2%, more preferably 0.195% or less, and most preferably 0.19% or less.

  The amount of Si and / or B introduced is expressed as the amount contained in the glass raw material composition. Si and / or B is introduced to suppress devitrification in the cooling process from the glass melt. When glass is obtained by a general melting method, various glass raw materials are weighed, prepared and mixed, put into a high-temperature melting furnace and vitrified, and the glass melt is clarified, stirred, and homogenized. , Solidify by cooling. The glass raw material can be selected from a wide variety of oxides, carbonic acid compounds, nitric acid compounds, sulfuric acid compounds, phosphoric acid compounds, halides, hydroxides, and the like of the desired glass constituent elements. Because of the complexity and infinite number of combinations, it is not uniquely determined, and the coordination number, ionic radius, and ionic valence of the elements present in the final glass are not unique, so they are expressed in elements. did.

  A glass having an optical constant having a refractive index (nd) of 1.41 to 1.47 and an Abbe number (νd) of 90 to 100 is suitable for a change in light wavelength even when a lens is made of this glass alone. Refractive index change (dispersion) is small, especially useful for optical equipment that uses light in the visible light region such as cameras, etc., but compact and highly accurate with low chromatic aberration in optical design combined with high refractive index and high dispersion glass Since an optical device can be realized, it is a very useful material in industry.

The glass of constitution 2 is a glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, and P is 0.1 to 0.1%. 5.0%, Al 1.0-20.0%, Ca 1.0-20.0%, Sr 1.0-20.0%, Ba 1.0-20.0%, F 30.0 to 60.0%, O is 1.0 to 20.0%, Mg is 0 to 10.0%, Y is 0 to 10.0%, and the refractive index (nd) is 1.41. ˜1.47, Abbe number (νd) has an optical constant in the range of 90-100.
The constituent elements that are the same as those in the first configuration are as described above, and are therefore omitted.

  Ca is a useful component having an effect of improving the chemical durability of glass while realizing low dispersion characteristics, among other glass modifying components. In order to obtain the effect sufficiently, it is desirable to contain 1.0% or more, more preferably 3.0% or more, and most preferably 5.0% or more. On the other hand, when excessively added, it becomes easy to produce an ion-bonding crystal with F which is a main glass skeleton component. Therefore, it is preferably 20.0% or less, more preferably 18.0% or less, and most preferably 15 0.0% or less is contained.

  Sr has the effect of adjusting the refractive index among the glass-modifying components, and is useful for improving the devitrification resistance of the glass when coexisting with other divalent elements (especially alkaline earth elements). Is an essential ingredient. In order to obtain the effect sufficiently, it is preferable to contain 1.0% or more, more preferably 3.0% or more, and most preferably 8.0% or more. On the other hand, if added excessively, the refractive index becomes too high, and it becomes difficult not only to realize the desired low refractive index and low dispersion characteristics, but also the devitrification resistance of the glass is deteriorated. More preferably, it contains 19.0% or less, and most preferably 18.0% or less.

  Ba is a useful component that has the effect of adjusting the refractive index among the glass modifying components and the effect of improving the devitrification resistance of the glass. In order to obtain the effect sufficiently, it is preferable to contain 1.0% or more, more preferably 3.0% or more, and most preferably 5.0% or more. On the other hand, when added excessively, not only the refractive index becomes too high, but also the specific gravity of the resulting glass increases and the chemical durability tends to deteriorate, so it is preferably 20.0% or less, more preferably 18 0.0% or less, most preferably 15.0% or less.

  Mg functions as a glass modifying component, and it is easy to obtain the effect of adjusting the refractive index and the effect of improving the chemical durability, so it can be arbitrarily contained. Even if it is not contained, it is possible to obtain the glass of the present invention, but if it is desired to improve chemical durability while realizing a desired refractive index, it may contain 0.3% or more. More preferably, it is more preferably 0.5% or more. On the other hand, when it is added excessively, the devitrification resistance of the glass is remarkably deteriorated. Therefore, it is preferably 10.0% or less, more preferably 8.0% or less, and most preferably 5.0% or less.

  Y is a trivalent glass-modifying component, and can be contained arbitrarily because it has the effect of adjusting the refractive index and the effect of improving the devitrification resistance of the glass. Even if it is not contained, it is possible to obtain the glass of the present invention, but if it is desired to improve the devitrification resistance while realizing a desired refractive index, it may contain 0.1% or more. More preferred. On the other hand, if added excessively, the refractive index of the glass tends to be higher than necessary, so that the upper limit is preferably 10.0% or less, more preferably 8.0% or less, and most preferably 6.0% or less. It is desirable to do.

  The glass of the said structure 3 is glass obtained by melting the glass raw material composition which contains less than 0.005-0.2% of Si and / or B with element mass%, Comprising: P is 1.0. -5.0%, Al 8.0-18.0%, Ca 5.0-15.0%, Sr 8.0-18.0%, Ba 5.0-15.0%, 35.0-55.0% F, 1.0-15.0% O, 0.3-5.0% Mg, 0.1-8.0% Y, and La 0-5 0.0% and / or Gd 0-5.0% and / or Li 0-3.0% and / or Na 0-3.0% and / or K 0-3.0%, It has an optical constant having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98.

A glass having an optical constant having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98 is combined with a commercially available high refractive index and high dispersion glass that can be easily procured from the market. It is a particularly useful material in the industry because it is possible to design a compact and highly accurate optical system with little chromatic aberration.
In order to stably obtain a glass having this refractive index and Abbe number, Configuration 3 is a configuration in which the types and configuration ratios of the constituent components described in Configuration 2 are further preferably set. A description of the overlapping components is omitted.
La and Gd can be arbitrarily added because the same effects as Y can be easily obtained as a trivalent glass modifying component. However, if added excessively, the refractive index of the glass tends to increase, so that it is 5.0% or less, more preferably 4.5% or less, and most preferably 4.0% or less.

  Li, Na, and K are monovalent glass modifying components, and by adding an appropriate amount, it is easy to obtain the effect of improving the devitrification resistance due to the multi-component of the glass component, so add arbitrarily. Is possible. However, monovalent glass modifying components tend to be ion-bonded crystals when combined with F forming the glass skeleton, and are each 3.0% or less, more preferably 2.5% or less, and most preferably 2.0%. The following.

  Although the preferable glass raw material form for obtaining the glass of the said structures 1-3 is mentioned later, it is not limited to the description matter of this specification.

  Each transition metal component such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, excluding Ti, is colored even when contained in a small amount by combining them individually or in combination. In order to cause absorption at the wavelength of the optical glass, it is preferable that the optical glass using the wavelength in the visible region does not substantially contain. Furthermore, each component of Pb, Th, Cd, Tl, As, Os, Be, and Se has tended to be refrained from being used as a harmful chemical material in recent years. Therefore, it is preferable not to include it substantially when the environmental impact is important.

  The element mass% ratio (Si + B + P + Al) / F shown in Configuration 4 is one of the indicators for judging the devitrification resistance of the glass, and is preferably in the range of 0.15 to 0.40. Of the molecules in this element mass% ratio, each element of Si and B is a component that improves the devitrification resistance of the glass by adding a small amount as described in paragraph [0017]. Moreover, each element of P and Al is an element (cation component) that forms a glass skeleton, and is a component that increases the viscosity of the glass melt and improves the devitrification resistance. On the other hand, the denominator F has the effect of lowering the viscosity of the glass melt. If this ratio is too small, the viscosity of the glass melt is low, and it becomes difficult to form a glass article, and the devitrification resistance is likely to be deteriorated, so that the productivity tends to be deteriorated. On the other hand, if this ratio is too large, the amount of F in the glass skeleton will be relatively too small, so that the devitrification resistance is likely to deteriorate and the desired optical constant (particularly low dispersion characteristics) is realized. It becomes difficult to do. Therefore, it is preferably 0.40 or less, more preferably less than 0.37, most preferably 0.35 or less, preferably greater than 0.15, more preferably greater than 0.18, and most preferably 0. 20 or more.

  As shown in Configuration 5, when (Si + B + P + Al) / F is within a predetermined range and the element mass% ratio Ba / Sr is in the range of 0.6 to 1.0, the devitrification resistance is further improved. The effect is easily obtained. If this Ba / Sr ratio is too small, it means that the relative ratio of Ba where the effect of improving devitrification resistance is easily obtained is too small, and the devitrification resistance of the glass tends to be deteriorated. Above, more preferably 0.62 or more, and most preferably 0.65 or more. On the other hand, if this ratio is too large, the refractive index tends to be larger than the desired value, so it is preferably 1.0 or less, more preferably 0.98 or less, and most preferably 0.95 or less.

Next, optical glasses having configurations 6 to 8 of the present invention will be described. In composition 6-8, the element mass% notation of each component represents each component contained in the raw material before melting in mass% for each element.
The structure 6 includes a glass raw material and a glass component for stably obtaining a glass having an optical constant having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98. Element. Since the role and effect about a glass component have already been demonstrated, they are omitted. Configuration 7 is a more preferable aspect of Configuration 6, and Configuration 8 is a more preferable aspect of Configuration 7.

  When glass is obtained by the melting method, the glass raw material composition undergoes a vitrification reaction, which is a chemical change, to form a glass melt, but in order to make the vitrification reaction proceed smoothly, the form and combination of the glass raw materials must be changed. It is important to consider.

  In general, the oxide raw material has a high melting point, and in the vitrification reaction of the entire glass raw material composition, the glass raw material tends to remain until the final stage.If the vitrification reaction temperature, that is, the melting temperature of the glass raw material is too low, Oxide raw material may remain unmelted. In order to prevent unmelted residue, it is considered to increase the melting temperature of the glass raw material or to increase the melting time. However, in the low refractive index low dispersion glass in the present invention, a large amount of F having high volatility is used. These measures are not preferred because they need to be included. Therefore, it is not preferable to use a large amount of oxide raw material in the glass raw material composition for obtaining the glass of the present invention.

The most inexpensive and readily available raw material form for introducing Si is an oxide (typically SiO ₂ ). In the present invention, Si is introduced into the glass from the beginning of the vitrification reaction. Therefore, it is preferable to introduce Si with a glass raw material other than the oxide raw material.
B ₂ O ₃ , which is an oxide of B, is an unstable compound and has a high hygroscopic property. Therefore, it needs to be carefully stored and managed, and inhibits stable production activities. It is preferable to introduce B.
The total amount of Si and / or B contained in the raw material is preferably less than 0.2%, more preferably 0.195% or less, most preferably 0.19% or less, preferably 0. The lower limit is 0.005%, more preferably 0.008%, and most preferably 0.01%.

Since the phosphoric acid complex salt is an essential source of P for the glass of the present invention, it is used as a glass raw material. The phosphoric acid complex salt has a lower melting point than the oxide raw material, and the vitrification reaction tends to proceed at a low temperature. Therefore, it is preferably used as a glass raw material for obtaining the glass of the present invention. Since the oxide raw material and / or the phosphoric acid compound raw material is an essential supply source of O for the glass of the present invention, it is necessary to use it as a glass raw material. It is necessary to keep in mind that it is introduced inside. In addition, it is also possible to use glass raw materials, such as a general carbonic acid compound, a nitric acid compound, a sulfuric acid compound, a hydroxide, as a supply source of O. However, these raw materials are decomposed during the vitrification reaction to release gas components (for example, carbon dioxide in the case of carbonic acid compounds), so that if used excessively, the glass melt will foam and be melted from the melting crucible. When the spilled or released gas component becomes bubbles and floats and disappears on the melt surface (bubbles repel), the volatilization of the F component in the glass melt tends to be promoted. When used, it is desirable to use a small amount (less than 5.0% in terms of the total mass% of the glass raw material).
P contained in the raw material is preferably 5.0%, more preferably 4.9%, and most preferably 4.8%, preferably 1.0%, more preferably 1.1%, Most preferably, the lower limit is 1.2%.
Since the fluoride raw material is an essential supply source of F for the glass of the present invention, it is used as an essential glass raw material.

  Configuration 7 is a more preferable aspect of Configuration 6, and Configuration 8 is a more preferable aspect of Configuration 7. In addition, about the role and effect about a glass structural component introduce | transduced from the glass raw material of the structure 7 and the structure 8, and a raw material form, it is the same as the above-mentioned structures 1-5.

Each elemental component of Al, Mg, Ca, Sr, and Ba is preferably introduced with a phosphate complex salt and / or a fluoride raw material as essential. As the phosphoric acid complex salt for introducing Al, Al (PO ₃ ) ₃ , AlPO _{4 and the} like, and as the fluoride raw material for introducing Al, AlF ₃ is preferable. Examples of the phosphate complex salt for introducing the alkaline earth metal element (R "= Mg, Ca, Sr, Ba) include alkaline earth metal elements such as R" (PO ₃ ) ₂ , R " ₂ P ₂ O ₇ As a fluoride raw material for introducing (R "= Mg, Ca, Sr, Ba), R" F ₂ is preferable.
Al contained in the raw material is preferably 20.0%, more preferably 18.0%, and preferably 3.0%, more preferably 8.0%.
Mg contained in the raw material is preferably 5.0%, more preferably 3.0%. Further, Mg may be contained, but it is preferable to contain 0.3% or more.
Ca contained in the raw material is preferably 20.0%, more preferably 15.0% as an upper limit, preferably 3.0%, more preferably 7.0%.
Sr contained in the raw material is preferably 20.0%, more preferably 18.0% as the upper limit, preferably 3.0%, more preferably 11.0% as the lower limit.
Ba contained in the raw material is preferably 20.0%, more preferably 15.0% as the upper limit, preferably 3.0%, more preferably 5.0%.
The sum of Sr + Ba is preferably in the range of 20.0% to 35.0%, and more preferably in the range of 22.0 to 33.0%.

Each element component of Y, La, and Gd is preferably introduced with a fluoride raw material as an essential component. Although introduction with a phosphoric acid complex salt is possible (for example, a metaphosphoric acid compound), these compounds are difficult to obtain and expensive, and therefore, when the glass of the present invention is to be obtained stably and economically, it is a fluoride. It is more preferable to introduce the raw materials (YF ₃ , LaF ₃ , GdF ₃ ) as essential.
Y contained in the raw material is preferably 8.0%, more preferably 6.0%, and most preferably less than 4.0%, preferably 0.01%, more preferably 0.5%. To do.
La contained in the raw material is preferably 5.0%, more preferably 4.0%, and most preferably 3.0%.
Gd contained in the raw material is preferably 5.0%, more preferably 4.0%, and most preferably 3.0%.

Each element component of the alkali metal element (R = Li, Na, K) is preferably introduced as a fluoride raw material in order to supply a large amount of F essential to the present invention to the glass. These fluorides are introduced with complex fluorides such as R ₂ SiF ₆ and R ₃ AlF ₆ because the RF form has too strong ionic bond of RF and the vitrification reaction does not proceed smoothly. It is preferable to do. When introducing by phosphoric acid compounds (including hydrates) such as RPO ₃ , R ₃ PO ₄ and R ₂ HPO ₄ , consideration is given so that P and O introduced from these raw materials become a predetermined amount.
The upper limit of Li contained in the raw material is preferably 3.0%, more preferably 2.0%, and most preferably 1.0%.
Na contained in the raw material is preferably 3.0%, more preferably 2.0%, and most preferably 1.0%.
K contained in the raw material is preferably 3.0%, more preferably 2.0%, and most preferably 1.0%.
In addition, F contained in the raw material is preferably 65%, more preferably 55% as the upper limit, preferably 35%, more preferably 40% as the lower limit.

Each elemental component of Cl introduced from a chloride raw material, Br introduced from a bromide raw material, and I introduced from an iodide raw material is substituted into a part of F, and is introduced into the glass. Since the devitrification resistance improving effect by crystallization and the use of an appropriate amount of these glass raw materials can promote the vitrification reaction and the defoaming effect in the glass, it can be used arbitrarily. However, if the Cl introduced from the chloride raw material is 3.0%, Br introduced from the bromide raw material and I introduced from the iodide raw material are more than 5.0% introduced into the glass, the ionic radius is Since these large elements are introduced into the glass in a large amount and destabilize the glass structure, the devitrification resistance of the glass is remarkably deteriorated. A more preferable upper limit value is 1.0% for all elemental components.
Further, O contained in the raw material is preferably 10.0%, more preferably 8.0% as the upper limit, preferably 0.1%, more preferably 0.5% as the lower limit.

  By adjusting the glass raw material composition so as to be in the limited range of the element mass% described in the configuration 7 and the configuration 8, the low refractive index and low dispersion glass described in the configurations 1 to 6 is generally melted. It becomes possible to acquire stably by the law.

Next, the glass of the structures 9-13 of this invention is demonstrated. In composition 9-13, the mass% notation of each component represents each component contained in the raw material before melting in mass% for each compound.
In order to obtain glass having optical constants in which the refractive index (nd) is 1.41 to 1.47 and the Abbe number (νd) is 90 to 100, It is shown. In this paragraph, “mass% based on the total mass of the glass raw material” is simply expressed as “%”.

Al (PO ₃ ) ₃ is a useful raw material for introducing Al, P, and O into glass, and promotes stable glass formation, and has an effect of increasing the mechanical strength and chemical durability of the obtained glass. There is. If the amount is too small, it is difficult to obtain this effect sufficiently. Therefore, the content is preferably 2.0% or more, more preferably 2.5% or more, and most preferably 3.0% or more. On the other hand, if used excessively, the refractive index and dispersion of the glass will increase, making it difficult to achieve the desired optical constant, so it is preferably 10.0% or less, more preferably 9.5% or less, most preferably, 9.0% or less.

AlF ₃ is a useful raw material for introducing Al and F into the glass, and has the effect of promoting the vitrification reaction and promoting the stable glass formation, and reduces the refractive index and dispersion of the resulting glass. effective. If the amount is too small, it becomes difficult to achieve a desired optical constant. Therefore, the content is preferably 20% or more, more preferably 22% or more, and most preferably 25% or more. On the other hand, if used excessively, the devitrification resistance of the glass deteriorates, so it is preferably 35% or less, more preferably 33% or less, and most preferably 30% or less.

CaF ₂ is a useful raw material for introducing Ca and F into glass, and an effect of reducing the dispersion and specific gravity of the obtained glass and an effect of promoting stable glass formation are obtained. If the amount is too small, it is difficult to obtain the effect sufficiently. Therefore, the content is preferably 15% or more, more preferably 16% or more, and most preferably 18% or more. On the other hand, when used excessively, the devitrification resistance of the glass deteriorates, so it is preferably 25% or less, more preferably 24% or less, and most preferably 22% or less.

SrF ₂ is a useful raw material for introducing Sr and F into glass, and an effect of adjusting the refractive index of the obtained glass and an effect of promoting stable glass formation are obtained. If the amount is too small, it is difficult to obtain the effect sufficiently. Therefore, the content is preferably 15% or more, more preferably 15.5% or more, and most preferably 16% or more. On the other hand, if it is used excessively, it becomes difficult to realize a desired optical constant, and the devitrification resistance of the glass deteriorates. Therefore, it is preferably 28% or less, more preferably 27% or less, and most preferably 25% or less. .

BaF ₂ is a useful raw material for introducing Ba and F into the glass, and an effect of adjusting the refractive index of the obtained glass and an effect of promoting stable glass formation are obtained. If the amount is too small, it is difficult to obtain the effect sufficiently. Therefore, the amount is preferably 5% or more, more preferably 6% or more, and most preferably 8% or more. On the other hand, when used excessively, not only the refractive index of the glass obtained becomes too high, but also the glass specific gravity becomes heavy and the chemical durability of the glass deteriorates, so it is preferably 20% or less, more preferably 18% or less. And most preferably 15% or less.

YF ₃ is a useful raw material for introducing Y and F into the glass, and an effect of adjusting the refractive index of the obtained glass and an effect of promoting stable glass formation are obtained. If the amount is too small, it is difficult to obtain the effect sufficiently. Therefore, the content is preferably 0.1% or more, more preferably 0.5% or more, and most preferably 1.0% or more. On the other hand, if it is used excessively, the refractive index of the resulting glass tends to be high, so it is preferably 10% or less, more preferably 9% or less, and most preferably 8% or less.
Adding Si introduced from the raw material excluding oxide in the range of 0.005 to less than 0.2 elemental mass% suppresses the occurrence of devitrification (crystal) inside the glass during the cooling process from the molten state. As described above, it is an important and indispensable element.

  The configuration 11 specifically shows a more preferable configuration of the raw material composition among the configurations 9 and 10. In this paragraph, “mass% based on the total mass of the glass raw material” is simply expressed as “%”, and the description of the elements overlapping with configurations 9 and 10 is omitted.

MgF ₂ is a useful raw material for introducing Mg and F into the glass, and an effect of adjusting the refractive index of the obtained glass and an effect of improving the chemical durability of the glass are obtained. If the amount is too small, the effect of enhancing the chemical durability is difficult to obtain. Therefore, the content is preferably 1% or more, more preferably 1.5% or more, and most preferably 2% or more. On the other hand, since the devitrification resistance of the glass deteriorates when used excessively, it is preferably 7% or less, more preferably 6.5% or less, and most preferably 6% or less.

Further, by setting the mass% ratio (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) to be less than 0.77, the devitrification resistance of the obtained glass can be further improved. . MgF ₂ and CaF ₂ , molecules of this mass% ratio, are raw materials that have a strong tendency to deteriorate devitrification when contained in a large amount, while denominator Al (PO ₃ ) ₃ and AlF ₃ are stable glass. Since this is a raw material that has a high effect of promoting formation and improving the devitrification resistance of glass, the smaller this ratio, the better the devitrification resistance of the resulting glass. This mass% ratio is preferably less than 0.77, more preferably less than 0.73, and most preferably 0.72 or less. When the mass% ratio is 0.5 or less, it is difficult to achieve a desired optical constant even if the glass is excellent in devitrification resistance.

  The structure 12 is a description regarding the raw material form for stably and economically obtaining the glasses described in the structures 1 to 11.

Since SiO ₂ and B ₂ O ₃ are oxides, as described above, they are raw material forms that tend to hinder a smooth vitrification reaction. When these are introduced into glass, it is desirable to use raw materials other than oxides such as fluorides or phosphoric acid compounds. It is not preferable to use a hydrate of B ₂ O ₃ (such as H ₃ BO ₃ ) as a raw material because water (H ₂ O) is generated in the vitrification reaction to promote F volatilization.

Ba (PO ₃ ) ₂ and BaCl ₂ are raw material forms that can easily form an alloy with a platinum group such as Pt, which is a material of general glass melting equipment, particularly during the vitrification reaction. Ba is particularly easy to form an alloy with Pt among platinum group ions, and an alloy accident is likely to occur particularly when a phosphoric acid compound is used as a glass raw material. In order to stably obtain the glass of the present invention without damaging the melting equipment, it is not preferable to use this raw material form. Further, Cl introduced from BaCl ₂ tends to invade Pt of the melting equipment and easily elutes a large amount of Pt ions into the glass. In particular, Pt ions are absorbed in a short wavelength region of 450 nm or less, and the light transmittance of the glass tends to deteriorate.

  In the raw material form of LiF, NaF and KF, not only is the ionic bondability of R—F so strong that the vitrification reaction does not proceed smoothly, but during the vitrification reaction, Pt of the melting instrument is ionized. Since it is easy to elute in a large amount in the glass, it is not preferable because absorption of Pt ions is likely to occur particularly in a short wavelength region of 450 nm or less and the light transmittance of the glass tends to deteriorate.

LiPF ₆ , NaPF ₆ , and KPF ₆ tend to ionize Pt of the melting apparatus and easily elute it in the glass in the vitrification reaction, so that absorption of Pt ions is likely to occur particularly in the short wavelength region of 450 nm or less. The light transmittance of the glass tends to deteriorate, which is not preferable. In addition, since these alkali metal composites are raw materials that are difficult to obtain and relatively expensive, it is desirable not to use them in order to obtain the glass of the present invention economically.

  Configuration 13 is a more specific requirement for obtaining the glass of the present invention stably and economically. Explanation of elements that overlap with the previous explanation is omitted.

Na ₂ SiF ₆ is a component that can introduce Na, Si, and F into the glass, and is a suitable raw material for introducing Si indispensable in the present invention. K ₂ SiF ₆ is a component that can introduce K, Si, and F into glass, and is a suitable raw material for introducing Si indispensable in the present invention. When these are used individually by 3.0% or more, excessive F is introduced into the glass, and not only the devitrification resistance of the glass is likely to deteriorate, but Na and K are excessively introduced into the glass. Therefore, the chemical durability is likely to deteriorate, so that it is preferably 3.0% or less, more preferably 2.8% or less, and most preferably 2.5% or less.

In order to introduce Si into the glass, either one of the glass raw materials may be used, or both may be used in combination, so the mass sum (Na ₂ SiF ₆ + K ₂ SiF ₆ ) is at least 0. 0.01% or more is necessary, preferably 0.03% or more, and most preferably 0.05% or more. On the other hand, when the total amount exceeds 5.0%, excessive F is introduced into the glass, and not only the devitrification resistance of the glass is likely to deteriorate, but Na and K are excessively introduced into the glass. As a result, the chemical durability deteriorates (→ if possible, it is changed to “easy to deteriorate”), so the preferable upper limit is 5.0% or less, more preferably 4.0% or less, and most preferably 3.0%. The following.

KHF ₂ is a useful glass raw material because an effect as an acidifying agent for directing a glass melt having a strong defoaming effect and reduction tendency to a neutral direction is obtained. When the reduction tendency of the glass melt is strengthened, Ba and P in the glass react with the melting equipment composed of platinum group metals and easily elute Pt ions into the glass. In severe cases, platinum group metals and alloys The possibility of an alloy accident in which the glass flows out of the alloy portion due to the formation of the film increases. If it is less than 0.1%, these effects cannot be obtained sufficiently. Therefore, it is preferably 0.1% or more, more preferably 0.13% or more, and most preferably 0.15% or more. On the other hand, since it will be easy to increase the volatilization amount of F in glass, when it uses for a glass raw material too much, Preferably, it is 3.0% or less, More preferably, it is 2.8%. Hereinafter, most preferably 2.5% or less.

NH ₄ F · HF is added arbitrarily as KHF ₂ because the defoaming effect of the glass melt and the effect as an acidifying agent for directing the glass melt having a strong reduction tendency to the neutral direction are obtained. It is possible. However, since the amount of HF gas introduced is larger than that of KHF ₂ , the upper limit is preferably 1.0%.

  Configuration 14 is a requirement for limiting the preferred range for further improving the devitrification resistance in the process of cooling the glass melt among the glasses according to any one of Configurations 6 to 13. By adjusting the element mass% ratio (Si + B + P + Al) / F to a ratio of 0.20 to 0.40 in the state of the glass raw material composition (raw material before melting), it is easy to obtain the glasses described in the constitutions 1 to 5. Become. If this ratio is too small, excessive F component is easily introduced into the glass, so that the viscosity of the glass melt is low, and it becomes difficult to form a glass article, and the devitrification resistance is likely to deteriorate. Therefore, productivity tends to deteriorate. On the other hand, if this ratio is too large, the amount of F in the glass skeleton is relatively decreased due to the vitrification reaction and volatilization of the F component during melting, and thus the devitrification resistance tends to deteriorate. Thus, it becomes difficult to achieve a desired optical constant (particularly low dispersion characteristics). Therefore, it is preferably 0.40, more preferably 0.35 or less, most preferably 0.30 or less, preferably 0.20 or more, more preferably 0.25 or more, and most preferably 0.27 or more. To do.

  Configuration 15 is a requirement to limit the most preferable range for further improving the devitrification resistance in the process of cooling the glass melt among the glasses according to any one of claims 6 to 13. is there. When (Si + B + P + Al) / F is within a predetermined range and the element mass% ratio Ba / Sr is in the range of 0.6 to 1.0, the effect of improving devitrification resistance is more easily obtained. If this Ba / Sr ratio is too small, it means that the relative ratio of Ba where the effect of improving devitrification resistance is easily obtained is too small, and the devitrification resistance of the glass tends to be deteriorated. Above, more preferably 0.62 or more, and most preferably 0.65 or more. On the other hand, if this ratio is too large, the refractive index tends to be larger than the desired value, so it is preferably 1.0 or less, more preferably 0.98 or less, and most preferably 0.95 or less.

  The configuration 16 is a requirement characterized in that devitrification hardly occurs in the process of cooling the glass melt in any one of the glasses of the configurations 1 to 15.

When glass is obtained by the economical continuous melt molding production method, the glass melt is kept at a low temperature and the viscosity is high in order to suppress the occurrence of streaky heterogeneous parts (striae) due to convection of the outflow glass. Molded with In the case of a glass composition in which the devitrification resistance of the glass is inferior, crystals are generated in the glass when the temperature of the glass melt is lowered. Crystal generation from the glass melt is affected not only by the temperature factor but also by the time factor. If the temperature is kept at a low temperature for a long time, crystals are generated from the glass melt by the time factor. When such glass is continuously formed for a long time (at least several days), crystals are generated in the melting equipment, and the crystals are mixed into the obtained solidified glass to obtain a homogeneous glass free from foreign matter. Or crystals may stay in the melting equipment and affect the flow of the effluent glass, resulting in non-uniform portions (streaks) in the resulting glass. In the case where there is a concern that the above phenomenon occurs, in the continuous melt molding production method with high economic efficiency, glass cannot be stably obtained. Therefore, another method with poor productivity has to be taken, which is inferior in economic efficiency.
1000 ° C. is a temperature sufficiently higher than the temperature at which crystals are generated from the glass melt, and 690 ° C., which holds the temperature for 60 hours, is a temperature close to the glass forming temperature of components 1 to 15. If it can be confirmed by this evaluation method that no crystals are formed inside the glass, it is easy to obtain a glass stably by applying a highly economical continuous melt molding production method.

The structure 17 evaluates the devitrification property of glass by differential thermal measurement (DTA). Although there is no melting point in glass, when the temperature of the glass is raised, crystals (devitrification) are generated above a certain temperature, and the crystals (devitrification) generated by further raising the temperature are melted. This devitrification disappearance (melting) temperature is expressed as Tm, and is detected as an endothermic peak in the DTA curve. On the other hand, when the glass melt is cooled after the crystal (devitrification) is sufficiently melted, heat generated by the generation of the crystal (devitrification) is observed in the DTA curve. This exothermic start temperature, that is, the crystal (devitrification) precipitation start temperature is expressed as Tx ₍ temperature _{decrease rate per minute)} . In the process of cooling the glass melt (DTA temperature decreasing process), the observed heat generation start temperature depends on the cooling rate of the glass melt. Crystallization (devitrification) is less likely to occur from the liquid state as the liquid state is rapidly cooled. Therefore, the heat generation start temperature is observed at a lower temperature as the temperature decrease rate is higher. A heat generation start temperature is measured at a different temperature decrease rate, and a value obtained by extrapolating them to a temperature decrease rate of 0 ° C./min is expressed as “devitrification temperature (Tx)”.
The larger (Tm−Tx) means that the crystal (devitrification) is less likely to occur in the cooling process from the melt. By setting this value to 15 ° C. or higher, the temperature of the glass can be lowered to a low temperature. Since crystals (devitrification) are unlikely to occur, it becomes easy to increase the glass viscosity at the time of molding, and it becomes easy to effectively suppress the occurrence of streaky non-uniform portions (striates) due to convection of the outflow glass. In order to stably and economically produce a desired low refractive index and low dispersion glass, (Tm−Tx) is more preferably 18 ° C. or higher, and most preferably 20 ° C. or higher.

The structure 18 is a requirement regarding the chemical durability of the glass of any one of the structures 1 to 17.
Acid resistance of the glass measured by Japanese Optical Glass Industrial Standard JOGIS06 ^-1999 "chemical durability of the measurement method of the optical glass (Powder Method)" is characterized by a grade 1-3.

  When processing glass into lenses and prisms, it is exposed to water, abrasives, and cleaning agents. At this time, the material having poor acid resistance is likely to elute the glass component, so the finish of the polished surface tends to be poor, and a great deal of labor must be applied to obtain a clean and smooth polished surface, which is uneconomical. Therefore, the acid resistance of the glass is preferably tertiary or higher.

  As described in Structures 18-21, the glass described in Structures 1-17 is useful as a base material for producing optical elements such as lenses and prisms, and the optical elements are used in cameras and projectors. Thus, highly accurate chromatic aberration characteristics can be realized.

  As a representative example of a method for producing a lens or a prism using the glass of the present invention as a base material, reheat press processing is given as the configuration 20, but it is not limited to this manufacturing method. For example, a technique such as mold press processing is used. It is possible to produce an optical element using

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by this example.

Tables 1 to 4 show that the refractive index (nd) is 1.41 to 1.47 and the Abbe number (νd) is 90 to 100, which can be stably obtained by a general melting method. Preferred raw material (No. 1-28) glass raw material constituent element composition, element mass% ratio (Si + B + P + Al) / F, and Ba / Sr ratio, refractive index (nd), for obtaining a low dispersion fluorophosphate glass Abbe number (νd), insulation test result, (Tm−Tx) value are shown. The glass raw material mass% and mass% ratio of each example of _{(MgF 2 + CaF 2) /} (Al (PO 3) 3 + AlF 3), described in Table 5-8. That is, each Example of Tables 5-8 changes the notation of the same composition as the corresponding Example of Tables 1-4.

Table 9 shows the glass compositions and various physical property values of comparative examples (Nos. A to E) of known optical glasses. Here, Comparative Example A is Example 6 of JP-A-10-212133, Comparative Examples B and C are Examples 3 and 5 of JP-A 63-14141, and Comparative Examples D and E are Example 2 and Example 7 of JP-A-06-1919876, and the refractive index (nd) and Abbe number (νd) in the table are the values described in the respective publications. The comparative example is interpreted to mean the glass raw material composition, and for Comparative Example A, the mol% notation is converted into the mass% notation, and the glass raw material is melted by the procedures described in the respective publications to obtain glass. .
Table 10 shows the glass raw material mass% and the mass% ratio (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) of Comparative Examples (No. A to E).

About the obtained optical glass, the refractive index (nd), the Abbe number (νd), the evaluation result of the heat retention test, and the powder method acid resistance were measured as follows.
(1) Refractive index (nd) and Abbe number (νd)
It measured about the optical glass obtained by making slow cooling temperature-fall rate -25 degreeC / hour.
(2) Thermal insulation test evaluation The obtained glass is crushed to a size of 5 mm or less, put into a platinum crucible with a capacity of 50 cc, put into an alumina furnace with a lid made of alumina, and kept warm for 1 hour. Subsequently, the temperature of the electric furnace is decreased at a rate of about 100 ° C./hour (from 1000 ° C. to 690 ° C. for 3 hours), and the temperature is kept in the electric furnace at 690 ° C. for 60 hours. The inside of the glass was visually observed under a bright light source, and “O” indicates that no devitrification (crystal) was observed, and “X” indicates that devitrification (crystal) occurred.
(3) Difference between devitrification disappearance temperature (Tm) and devitrification temperature (Tx) Tm-Tx
The obtained glass is crushed to a particle size of 425 to 600 μm, and about 200 mg of the crushed glass sample is weighed, put in an alumina DTA crucible, and detected in the process of heating to 800 ° C. at a heating rate of 10 ° C./min. Among the endothermic peaks of the thermal curve, the highest endothermic peak temperature is defined as the devitrification disappearance temperature Tm. After reaching 800 ° C., the heat generation start temperature Tx ₍₋₅₎ at the highest temperature of the suggested heat curve detected in the process of cooling to 300 ° C. at a temperature decrease rate of 5 ° C./min, and similarly after reaching 800 ° C. The heat generation start temperature Tx ₍₋₁₀₎ at the highest temperature of the suggested heat curve detected in the process of cooling to 300 ° C. at a temperature decrease rate of 10 ° C./min is measured twice, and from these values, the temperature decrease rate is 0 The temperature extrapolated to ° C./min is defined as the devitrification temperature (Tx), and the difference (Tm−Tx) is calculated.
Table 1 shows Tm-Tx of Example 1 and Comparative Example D, and FIG. 1 shows the relationship between the heat generation start temperature and the temperature lowering rate.
(4) Powder Method acid resistance acid resistance (class) is the Japanese Optical Glass Industrial Standard "chemical durability of the measurement method of the optical glass (Powder Method)" JOGIS06- based on ^1999, particle size 425～ the resulting glass Crush the glass sample to 600μm, take a specific gravity gram, put it in a platinum basket, put the platinum basket into a quartz glass round bottom flask containing 10mmol / l (= 0.01N) nitric acid aqueous solution, and boil water bath After processing for 60 minutes, the weight loss rate (%) of the treated glass sample is calculated. If the weight loss rate is less than 0.20%, it is Class 1, and the weight loss rate is less than 0.20 to 0.35%. The case of No. 2 is grade 2, and the case where the weight loss rate is less than 0.35 to 0.65% is grade 3. The smaller the number of grades, the better the water resistance of the glass.

  The glasses of the examples of the present invention described in Tables 1 to 8 were weighed and mixed at a predetermined ratio using the ordinary optical glass raw materials described in this specification, and then covered with a refractory such as platinum or alumina. In a platinum crucible with a mechanism capable of melting, melting in a temperature range of 900 to 1050 ° C. in a temperature range of 900 to 1050 ° C. for 3 to 4 hours according to the melting difficulty of the glass composition, stirring and homogenizing, and then 2 to 3 in the electric furnace It was obtained by lowering to 680 ° C. over time, casting into a mold, etc., and slow cooling.

As shown in Tables 1 to 8, in the preferred embodiments of the present invention, all of the desired optical constants were realized, and devitrification was not confirmed in the glass in the heat retention test. It was found to be a glass having devitrification. In addition, the acid resistance of the powder method was all in the third grade. Furthermore, in Examples 1, 6 to 20, 22 to 25, 27, and 28, the element mass% ratio (Si + B + P + Al) / F is 0.27 to 0.30, and the element mass% ratio Ba / Sr is Since it is 0.6 or more, (Tm−Tx) is 20 ° C. or more. On the other hand, in Comparative Examples A and D shown in Table 9, although optical constants are realized, Si and / or B are used as the glass raw material. The element mass% ratio (Si + B + P + Al) / F based on the total mass of the glass raw material is less than 0.27 and the mass% ratio based on the total mass of the glass raw material ( Since MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) is greater than 0.77, the glass substrate has poor devitrification resistance, and the glass is devitrified in a 60-hour heat retention test at 690 ° C. Occurrence was confirmed. Further, Comparative Examples B and C do not contain Si and / or B in the glass raw material, and the element mass% ratio (Si + B + P + Al) / F based on the total mass of the glass raw material is more than 0.30. Since the glass substrate is large and the devitrification resistance is poor, a transparent glass cannot be obtained for Comparative Example B (crystals are generated inside and become cloudy). In Comparative Example C, a heat insulation test at 690 ° C. for 60 hours is performed. The occurrence of devitrification was confirmed inside the glass. In Comparative Example C, not only that, but there was much Ba in the glass, so the powder method acid resistance was quaternary. Comparative Example E does not contain Si and / or B in the glass raw material, and the element mass% ratio (Si + B + P + Al) / F, Ba / Sr ratio, and the total mass of the glass raw material are based on the total mass of the glass raw material. Each of the reference mass% ratios (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) is slightly out of the preferred range, but devitrification occurs inside the glass in the 60-hour heat retention test at 690 ° C. Was not recognized. However, the glass viscosity at 690 ° C. is very low, and at this temperature, streaky non-uniform portions (streaks) are likely to occur due to convection of the outflow glass, and it is considered difficult to obtain highly homogeneous optical glass. When (Tm−Tx) by DTA measurement was measured, the value was 6 ° C., and it is considered that it is difficult to sufficiently increase the glass viscosity at the time of molding, and it is difficult to obtain a desired optical glass stably and economically. Conceivable.

  Moreover, when the glass of the Example described in Tables 1-8 was cold-worked or reheat-pressed, problems such as devitrification did not occur inside the glass, and could be stably processed into various lenses and prism shapes. . Moreover, when the precision mold press molding process was implemented about the glass of the Example whose glass softening temperature is comparatively low, it was possible to acquire a favorable lens.

  When the lens or prism manufactured as described above was mounted on a camera or projector and the imaging characteristics were confirmed, it was possible to realize an optical system with small chromatic aberration, particularly in the visible region.

Although the present invention has been described in detail for the purpose of illustration, this embodiment is only for the purpose of illustration, and many modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention. Will be understood.

  According to the present invention, a refractive index (nd) of 1.41 to 1.47, which is a glass material suitable for a projection lens and a prism of an optical apparatus typified by a camera or projector that requires high-accuracy chromatic aberration characteristics. Moreover, devitrification (crystals) that occurs when an ultra-low refractive index ultra-low dispersion glass having an Abbe number (νd) of 90 to 100 is cooled from a molten state, which is a problem during glass production, is effectively suppressed. Thus, it is possible to stably obtain lenses and prisms of imaging devices such as high-precision cameras and image projection (reproduction) devices such as projectors using this optical glass.

It is a graph which shows the relationship of the heat_generation | fever start temperature and the temperature-fall rate about Example 1 and Comparative Example D.

Claims (20)

Glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, wherein P is 0.1 to 5.0%, Al 1.0 to 20.0%, F 30.0 to 60.0%, O 1.0 to 20.0%, and one or more of Ca, Sr and Ba are essential. And an optical constant having a refractive index (nd) of 1.41-1.47 and an Abbe number (νd) of 90-100. Glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, wherein P is 0.1 to 5.0%, Al 1.0-20.0%, Ca 3.0-20.0%, Sr 1.0-20.0%, Ba 1.0-2
0.0%, F 30.0-60.0%, O 1.0-20.0%, Mg 0-10.0%, Y 0-10.0%, nd) is a glass having an optical constant of 1.41-1.47 and an Abbe number (νd) of 90-100. Glass obtained by melting a glass raw material composition containing elemental mass% and Si and / or B less than 0.005 to 0.2%, wherein P is 1.0 to 5.0%, Al 8.0 to 18.0%, Ca 3.0 to 18.0%, Sr 3.0 to 19.0%, Ba 3.0 to 1
8.0%, F 32.0-58.0%, O 1.0-18.0%, Mg 0.3-8.0
% And Y from 0.1 to 8.0% and La from 0 to 5.0% and / or Gd from 0 to 5.0% and / or Li from 0 to 3.0% and / or Na from 0 -3.0% and / or K contains 0-3.0%, and has an optical constant in the range of refractive index (nd) of 1.42-1.46 and Abbe number (νd) of 92-98. Glass. It is a glass as described in any one of Claims 1-3, Comprising: Element mass% ratio (Si + B + P + Al) / F is a glass whose range is 0.15-0.40. It is glass as described in any one of Claims 1-3, Comprising: Element mass% ratio (Si + B + P + Al) / F is 0.20-0.35, and element mass% ratio Ba / Sr is 0.6-. Glass in the range of 1.0. A glass having an optical constant having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98,
Based on the total mass of the glass raw material,
Si and / or B introduced from the raw material excluding oxide is 0.005 to less than 0.2%,
1.0 to 5.0% of P introduced from the phosphoric acid compound raw material,
3.0 to 20.0% of Al introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
Mg introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride is 0.0 to 5.
0%,
3.0 to 20.0% of Ca introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
3.0 to 20.0% of Sr introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
3.0 to 20.0% of Ba introduced from a raw material essentially containing a phosphoric acid compound and / or fluoride,
0.01 to less than 8.0% of Y introduced from the raw material essentially containing fluoride,
0.0 to 5.0% of La introduced from a raw material essentially containing fluoride,
0.0 to 5.0% of Gd introduced from a raw material essentially containing fluoride,
0.0 to 3.0% of Li introduced from a raw material essentially containing fluoride,
0.0 to 3.0% of Na introduced from the raw material containing the fluoride essential,
0.0 to 3.0% of K introduced from a raw material essentially containing fluoride,
35 to 65% of F introduced from a raw material essentially containing fluoride,
0.0 to 3.0% of Cl introduced from the chloride raw material,
0.0 to 5.0% of Br introduced from bromide raw material,
0.0 to 5.0% of I introduced from the iodide raw material,
0.1 to 10% of O introduced from phosphoric acid compound raw material and oxide raw material
A glass obtained by melting a glass raw material composition characterized by containing. Element mass%
Si and / or B introduced from the raw material excluding oxide is 0.005 to less than 0.2%,
1.0 to 5.0% of P introduced from the phosphoric acid compound raw material,
8.0 to 18.0% of Al introduced from the phosphoric acid compound raw material and / or fluoride raw material,
0.3 to 3.0% of Mg introduced from the phosphoric acid compound raw material and / or fluoride raw material,
7.0 to 15.0% of Ca introduced from the phosphoric acid compound raw material and / or fluoride raw material,
11.0 to 18.0% of Sr introduced from the phosphoric acid compound raw material and / or fluoride raw material,
Ba introduced from the phosphoric acid compound raw material and / or fluoride raw material is 5.0 to 15.0%,
However, the mass% sum (Sr + Ba) is 20.0-35.0%,
0.5 to less than 6% of Y introduced from the fluoride raw material,
0.0 to 4.0% La introduced from the fluoride raw material,
0.0 to 4.0% of Gd introduced from the fluoride raw material,
0.0 to 2.0% of Li introduced from the fluoride raw material,
0.0 to 2.0% of Na introduced from the fluoride raw material,
0.0 to 1.0% of K introduced from the fluoride raw material,
40 to 55% of F introduced from the fluoride raw material,
0.0 to 1.0% of Cl introduced from the chloride raw material,
0.0 to 1.0% of Br introduced from bromide raw material,
0.0 to 1.0% of I introduced from the iodide raw material,
0.5 to 8% of O introduced from phosphoric acid compound raw material and oxide raw material
The glass according to claim 6, which is obtained by melting a glass raw material composition containing the glass raw material composition. Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.0 to 10.0%,
20-35% AlF ₃
CaF ₂ 15-25%,
15 to 28% of SrF ₂
BaF ₂ 5-20%,
0.1 to 10.0% of YF ₃
Melting a glass raw material composition containing less than 0.005 to 0.2% of Si and / or B introduced from the raw material excluding oxides in elemental mass%. Glass having an optical constant having a refractive index (nd) of 1.41 to 1.47 and an Abbe number (νd) of 90 to 100. Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.0 to 10.0%,
20-35% AlF ₃
CaF ₂ 15-25%,
15 to 28% of SrF ₂
BaF ₂ 5-20%,
0.1 to 10.0% of YF ₃
Melting a glass raw material composition containing less than 0.005 to 0.2% of Si and / or B introduced from the raw material excluding oxides in elemental mass%. The glass as described in any one of Claims 1-7 obtained by these. Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.5 to 10.0%,
AlF ₃ and 22 to 33 percent,
₁ to 7.0% MgF ₂
16-24% CaF ₂
However, the mass% ratio (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) is less than 0.77, and SrF ₂ is 15.5 to 27%.
BaF ₂ 6-18%,
YF ₃ 0.5-9.0%,
A glass raw material composition containing less than 0.005 to 0.2% of Si and / or B introduced from a raw material excluding oxides in elemental mass%. The glass according to claim 8 or 9, which is obtained by melting an object. A glass according to any one of claims _{1~10, SiO 2, B 2 O} 3, Ba (PO 3) 2, BaCl 2, LiF, NaF, KF, LiPF 6, NaPF 6, KPF 6 A glass obtained by melting a glass raw material composition characterized by not containing any of the above. Based on the total mass of the glass raw material,
Al (PO ₃ ) ₃ is 2.5 to 10.0%,
AlF ₃ and 22 to 33 percent,
₁ to 7.0% MgF ₂
16-24% CaF ₂
However, the mass% ratio (MgF ₂ + CaF ₂ ) / (Al (PO ₃ ) ₃ + AlF ₃ ) is less than 0.73, and SrF ₂ is 15.5 to 27%.
BaF ₂ is less than 6-18%,
YF ₃ 0.5-9.0%,
Na ₂ SiF ₆ 0.0-3.0%,
The K ₂ SiF ₆ 0.0~3.0%,
However, the mass sum (Na ₂ SiF ₆ + K ₂ SiF ₆ ) is 0.01 to 5.0%,
0.1 to 3.0% of KHF ₂ ,
NH ₄ F · HF is 0.0 to 1.0%
Melting glass raw material composition characterized by containing SiO ₂ , B ₂ O ₃ , Ba (PO ₃ ) ₂ , BaCl ₂ , LiF, NaF, KF, LiPF ₆ , NaPF ₆ , KPF ₆ Glass having a refractive index (nd) of 1.42 to 1.46 and an Abbe number (νd) of 92 to 98. It is glass as described in any one of Claims 6-12, Comprising: (Si + B + P + Al) / F is adjusted in the range of 0.20-0.40 by element mass% on the basis of the total mass of a glass raw material. A glass obtained by melting a glass raw material composition. It is glass as described in any one of Claims 6-12, Comprising: It is element mass% on the basis of the total mass of a glass raw material, (Si + B + P + Al) / F is 0.27-0.30, and Ba / Glass obtained by melting a glass raw material composition characterized in that Sr is adjusted to a range of 0.6 to 1.0. The glass according to any one of claims 1 to 14, wherein the glass is devitrified (crystallized) even after being cooled to 690 ° C from a melted state at 1000 ° C and then kept at 690 ° C for 60 hours. ) Does not occur. It is a glass as described in any one of Claims 1-15, Comprising: The devitrification temperature (Tx) calculated from the devitrification loss temperature (Tm) in the temperature rising process in DTA measurement, and the heat generation start temperature in the temperature decreasing process ) Having a difference of 15 ° C. or more. A glass according to any one of claims 1 to 16, the acid resistance of the glass measured by Japanese Optical Glass Industrial Standard JOGIS06- ¹⁹⁹⁹ "chemical durability of the measurement method of the optical glass (Powder Method)" Is a grade 1-3. The optical element which uses as a base material the glass as described in any one of Claims 1-17. An optical element produced by reheat pressing the glass according to any one of claims 1 to 17 . An optical apparatus using the optical element according to claim 18 or 19 .

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