JP2018150199A - Optical glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical glass with excellent devitrification resistance and a high refractive index.SOLUTION: An optical glass contains, in mass%, 25-40% PO, 0-4% SiO+BO+AlO, 0-11% ZnO, 1.5-6% LiO, 1-20% NaO, 0-7% KO, 1-11% TiO, 10-30% NbO, 0-15% BiO, and 0-10% WO.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical glass.

For applications such as optical pickup lenses for CD, MD, DVD and other optical disk systems, imaging lenses for digital cameras, video cameras, camera-equipped mobile phones, and transmission / reception lenses used for optical communication, the refractive index nd is 1. A high refractive index glass lens of 65 to 1.85 is required. Conventionally, as a high refractive index glass lens, for example, B ₂ O ₃ —ZnO—La ₂ O ₃ based glass has been used. (For example, see Patent Document 1)

JP 2002-362938

  As a method for producing a glass lens, once molten glass is formed into an ingot, and then the glass material cut out to an appropriate size is polished, followed by mold pressing, and molten glass is dropped from the nozzle tip to form a droplet. There is known a method of performing mold pressing after polishing a glass material formed by so-called droplet forming or without polishing.

However, B ₂ O ₃ —ZnO—La ₂ O ₃ glass has a problem that workability is low because devitrification is high and liquid phase viscosity is reduced. That is, since the B ₂ O ₃ —ZnO—La ₂ O ₃ based glass has a strong tendency to devitrify, the mass productivity is poor when an ingot is produced by rapidly casting molten glass. In addition, since the molten glass is dropped from the tip of the nozzle in the droplet forming, the lower limit of the molding viscosity of the glass capable of forming the droplet is about 10 ^0.5 dPa · s. However, B ₂ O ₃ —ZnO—La ₂ O ₃ glass is devitrified at a low viscosity of 10 ^0.5 dPa · s or less, and is not suitable for droplet forming. If the liquid is dropped at a viscosity of 10 ^0.5 dPa · s or less, the glass flows out in a continuous flow, and the liquid droplet cannot be formed.

  In view of the above problems, an object of the present invention is to provide a high refractive index optical glass excellent in devitrification resistance.

The optical glass of the present invention is, by mass%, P ₂ O ₅ 25-40%, SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ 0-4%, ZnO 0-11%, Li ₂ O 1.5-6%. , Na ₂ O 1-20%, K ₂ O 0-7%, TiO ₂ 1-11%, Nb ₂ O ₅ 10-30%, Bi ₂ O ₃ 0-15%, WO ₃ 0-10% It is characterized by doing. In the present invention, excellent devitrification resistance is achieved by regulating P ₂ O ₅ to 25% by mass or more and SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ to 4% by mass or less. Further, TiO ₂ 1% by mass or more is a component for increasing the refractive index, by regulating the _Nb 2 _{O 5} more than 10 wt%, has achieved a high refractive index. Here, “SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ ” means the total content of SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ .

  The optical glass of the present invention preferably further contains MgO + CaO + SrO + BaO 0 to 2% by mass. Here, “MgO + CaO + SrO + BaO” means the total content of MgO, CaO, SrO and BaO.

The optical glass of the present invention preferably further contains, in mass%, ZrO ₂ 0 to 5% and La ₂ O ₃ 0 to 5%.

The optical glass of the present invention preferably contains substantially no PbO, As ₂ O ₃ or GeO ₂ . Here, “substantially does not contain PbO, As ₂ O ₃ , GeO ₂ ” means that these components are not intentionally added to the glass and means that unavoidable impurities are completely eliminated. Does not mean. More objectively, it means that the contents of PbO, As ₂ O ₃ and GeO ₂ are each less than 0.1%.

  The optical glass of the present invention preferably has a refractive index (nd) of 1.65 to 1.85. “Nd” is the refractive index at the d-line.

  The optical glass of the present invention preferably has a refractive index (n1310) of 1.64 to 1.84. “N1310” is the refractive index at a wavelength of 1310 nm.

  The optical glass of the present invention preferably has an Abbe number of 20 to 35.

  The optical glass of the present invention preferably has a glass transition point of 500 ° C. or lower.

The optical glass of the present invention preferably has a thermal expansion coefficient at 30 to 300 ° C. of 110 × 10 ⁻⁷ / ° C. or higher.

  The optical glass of the present invention preferably has an internal transmittance at 450 nm of 98% or more. The “internal transmittance” refers to the transmittance excluding the surface reflection loss on the incident side and the emission side of the sample. Further, the “internal transmittance” in the present invention refers to the internal transmittance at a thickness of 10 mm, and specifically, is calculated from the measured values of the transmittance including the respective surface reflection losses of the thicknesses of 5 mm and 10 mm.

  The optical glass of the present invention preferably has a liquidus viscosity of 10 dPa · s or more.

  The optical glass of the present invention is preferably used for press molding.

  The optical glass lens of the present invention is made of the above optical glass.

  The lens cap of the present invention includes a metal shell composed of a cylindrical side wall portion, an end wall portion provided at the tip of the side wall portion and having a lens holding hole at the center thereof, and a lens holding of the metal shell. The above-mentioned optical glass lens sealed and fixed in the hole, and a sealing material for fixing the optical glass lens in the lens holding hole of the metal shell.

  ADVANTAGE OF THE INVENTION According to this invention, the high refractive index optical glass excellent in devitrification resistance can be provided.

It is a typical sectional view showing composition of a lens cap.

The optical glass of the present invention is, by mass%, P ₂ O ₅ 25-40%, SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ 0-4%, ZnO 0-11%, Li ₂ O 1.5-6%. , Na ₂ O 1-20%, K ₂ O 0-7%, TiO ₂ 1-11%, Nb ₂ O ₅ 10-30%, Bi ₂ O ₃ 0-15%, WO ₃ 0-10% To do. Below, the reason which specified content of each component as mentioned above is explained in full detail. Unless otherwise specified, the following “%” means “mass%”.

P ₂ O ₅ has the effects of improving devitrification resistance and increasing the liquidus viscosity, reducing the high temperature viscosity of the glass, and further reducing the glass transition point. The content of P ₂ O ₅ is 25 to 40%, preferably 26 to 38%, 27 to 36%, and particularly preferably 28 to 34%. When the content of P ₂ O ₅ is too small, the effect is difficult to obtain. On the other hand, when the content of P ₂ O ₅ is too large, weather resistance tends to deteriorate, also tends to fuse to the glass mold during the press molding.

SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ have the effect of improving the weather resistance. The content of SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ is 0 to 4%, preferably 0 to 3%, particularly preferably 0.1 to 2%. When the content of SiO ₂ + B ₂ O ₃ + Al ₂ O ₃ is too large, the devitrification resistance is deteriorated, the liquidus viscosity is liable to be lowered, the refractive index is liable to be lowered, and the solubility of the glass is further deteriorated. It becomes easy to do.

_A preferable range of the content of SiO _2, B 2 _{O 3} and _Al 2 _{O 3} is as follows.

The content of SiO ₂ is preferably 0 to 4%, 0 to 3%, particularly preferably 0.1 to 2%.

The content of B ₂ O ₃ is preferably 0 to 4%, 0 to 3%, particularly preferably 0.1 to 2%.

The content of Al ₂ O ₃ is preferably 0 to 4%, 0 to 3%, particularly preferably 0.1 to 2%.

  ZnO has the effects of lowering the high temperature viscosity of the glass and lowering the glass transition point while maintaining weather resistance. The content of ZnO is 0 to 11%, preferably 1 to 8%, particularly preferably 2 to 5%. If the ZnO content is too large, the weather resistance tends to deteriorate, and the glass tends to be fused to the mold during press molding.

Li ₂ O has the effects of reducing the high temperature viscosity of the glass and significantly reducing the glass transition point. The content of Li ₂ O is 1.5 to 6%, preferably 2 to 5%, particularly preferably 2 to 4%. When the Li 2 _O content is too small, the effect is difficult to obtain. On the other hand, when the content of Li 2 _O is too large, weather resistance tends to deteriorate, also the devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

Na ₂ O has an effect of lowering the high temperature viscosity of the glass and remarkably lowering the glass transition point. The content of Na ₂ O is 1 to 20%, preferably 3 to 18%, 5 to 16%, particularly preferably 7 to 14%. When the Na 2 _O content is too small, the effect is difficult to obtain. On the other hand, when the content of Na 2 _O is too large, weather resistance tends to deteriorate, also the devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

K ₂ O has an effect of lowering the high temperature viscosity of the glass and lowering the glass transition point. The content of K ₂ O is 0 to 7%, preferably 0 to 6%, 0 to 5%, particularly preferably 0.1 to 4%. When the content of K 2 _O is too large, weather resistance tends to deteriorate, also the devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

TiO ₂ has the effect of increasing the refractive index and improving the weather resistance. The content of TiO ₂ is 1 to 11%, preferably 2 to 10%, particularly preferably 3 to 9%. When the content of TiO ₂ is too small, the effect is difficult to obtain. On the other hand, when the content of TiO ₂ is too large, the glass is colored and the transmittance is lowered, or the devitrification resistance is deteriorated and the liquid phase viscosity is liable to be lowered.

Nb ₂ O ₅ is effective in increasing the refractive index and improving the weather resistance. The content of Nb ₂ O ₅ is 10 to 30%, preferably 12 to 28%, 14 to 26%, 16 to 24%, and particularly preferably 18 to 22%. When the content of Nb ₂ O ₅ is too small, the effect is difficult to obtain. On the other hand, when the content of Nb ₂ O ₅ is too large, it lowered the glass is colored transmittance and devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

Bi ₂ O ₃ has the effect of increasing the refractive index and significantly lowering the glass transition point. The content of Bi ₂ O ₃ is 0 to 15%, preferably 0 to 12%, particularly preferably 1 to 9%. If the content of Bi ₂ O ₃ is too large, it lowered the glass is colored transmittance and glass tends to fuse to the press die.

WO ₃ is effective in increasing the refractive index and improving the weather resistance. The content of WO ₃ is 0 to 10%, preferably 3 to 9%, particularly preferably 6 to 9%. When the content of WO ₃ is too large, it lowered the glass is colored transmittance and devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

  In addition to the above components, the following various components can be contained.

  MgO, CaO, SrO and BaO have the effect of lowering the high temperature viscosity of the glass and lowering the glass transition point while maintaining the weather resistance. The content of MgO + CaO + SrO + BaO is preferably 0 to 2%, particularly preferably 0.1 to 1%. When there is too much content of MgO + CaO + SrO + BaO, devitrification resistance will deteriorate, liquid phase viscosity will fall, a weather resistance will deteriorate easily, and also glass will become easy to melt | fuse to a metal mold | die at the time of press molding.

  In addition, the preferable range of content of MgO, CaO, SrO, and BaO is as follows.

  The content of MgO is preferably 0 to 2%, particularly preferably 0 to 1%.

  The content of CaO is preferably 0 to 2%, particularly preferably 0.1 to 1%.

  The content of SrO is preferably 0 to 2%, particularly preferably 0 to 1%.

  The BaO content is preferably 0 to 2%, particularly preferably 0 to 1%.

ZrO ₂ has the effect of increasing the refractive index and improving the weather resistance. The content of ZrO ₂ is preferably 0 to 5%, 0 to 3%, particularly preferably 0 to 1%. When the content of ZrO ₂ is too large, it lowered the glass is colored transmittance and devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

La ₂ O ₃ has effects of increasing the refractive index and improving the weather resistance. The content of La ₂ O ₃ is preferably 0 to 5%, 0 to 3%, particularly preferably 0.1 to 1%. When the content of La ₂ O ₃ is too large, it lowered the glass is colored transmittance and devitrification resistance is deteriorated liquid phase viscosity tends to decrease.

Sb ₂ O ₃ has an effect of defoaming, and also has an effect of suppressing coloring due to Pt ions (mixed in the glass as impurities by several ppm). The content of Sb ₂ O ₃ is preferably 0 to 1%, 0 to 0.09%, particularly preferably 0 to 0.08%. Since Sb ₂ O ₃ has a strong oxidizing power, if the content of Sb ₂ O ₃ is too large, it will oxidize metals such as Pt and Rh used in the melting container and promote the deterioration of the melting container. It tends to decrease.

SnO ₂ has a defoaming effect. The SnO ₂ content is preferably 0 to 1%, 0 to 0.09%, particularly preferably 0 to 0.08%. When the content of SnO ₂ is too large, it tends to be devitrified.

Since PbO and As ₂ O ₃ are harmful, it is preferable that they are not substantially contained.

Since GeO ₂ is a rare raw material and leads to an increase in the raw material cost, it is preferable not to contain it substantially.

  Moreover, since Cu, Ag, Pr, and Br are components which color glass, it is preferable that they are not substantially contained. Considering the influence on the environment, Cd is preferably not substantially contained. “Substantially free of Cu, Ag, Pr, Br, and Cd” means that these components are not intentionally added to the glass, and that unavoidable impurities are completely eliminated. It doesn't mean. More objectively, it means that the content of Cu, Ag, Pr, Br, Cd is less than 0.1%.

  The optical glass of the present invention preferably has a refractive index nd of 1.65 to 1.85, 1.67 to 1.83, particularly 1.68 to 1.81, and a refractive index at 1310 nm of 1.64 to 1.64. It is preferably 1.84, 1.66 to 1.82, particularly 1.69 to 1.80. Further, the Abbe number is preferably 20 to 35, 22 to 33, and particularly preferably 24 to 31.

  The optical glass of the present invention preferably has a glass transition point of 500 ° C. or lower, 480 ° C. or lower, particularly 460 ° C. or lower. Although the minimum of a glass transition point is not specifically limited, Actually, it is 400 degreeC or more. Further, the softening point tends to be 700 ° C. or lower, 680 ° C. or lower, particularly 650 ° C. or lower. The lower limit of the softening point is not particularly limited, but is practically 550 ° C. or higher. When the glass transition point and the softening point are low, the press molding temperature is low and the deterioration of the mold is easily suppressed.

The optical glass of the present invention preferably has a thermal expansion coefficient of 110 × 10 ⁻⁷ / ° C. or higher, 120 × 10 ⁻⁷ / ° C. or higher, particularly 130 × 10 ⁻⁷ / ° C. or higher in the range of 30 to 300 ° C. . The upper limit of the thermal expansion coefficient is not particularly limited, but is practically 170 × 10 ⁻⁷ / ° C. or less. If the thermal expansion coefficient is too low, it becomes difficult to release the optical glass from the press mold after press molding and cooling.

  The optical glass of the present invention preferably has an internal transmittance at 450 nm of 98%, 98.5%, particularly 99% or more.

  The optical glass lens of the present invention preferably has a liquidus viscosity of 10 dPa · s or more. When the liquid phase viscosity is 10 dPa · s or more, it is suitable for droplet forming.

  Next, a method for producing the optical glass lens of the present invention will be described.

  First, after preparing a glass raw material so that it may become a desired composition, it fuse | melts with a glass melting furnace. In order to obtain homogeneous glass, the melting temperature is preferably 1150 ° C. or higher, 1200 ° C. or higher, particularly 1250 ° C. or higher. Note that the melting temperature is preferably 1450 ° C. or lower, 1400 ° C. or lower, 1350 ° C. or lower, particularly 1300 ° C. or lower from the viewpoint of preventing glass coloring due to Pt melting from platinum metal constituting the melting vessel.

  Further, if the melting time is too short, there is a possibility that sufficient defoaming cannot be performed. Therefore, the melting time is preferably 2 hours or more, particularly 3 hours or more. However, from the viewpoint of preventing glass coloring due to Pt penetration from the melting vessel, the melting time is preferably within 8 hours, particularly within 5 hours.

  Next, molten glass is dropped from the tip of the nozzle to produce droplet glass, and optical glass is obtained. Alternatively, a molten glass is rapidly cast to produce a glass block, which is then ground, polished and washed to obtain an optical glass.

  Subsequently, the optical glass is put into a precision-processed mold and press-molded while being heated until it becomes softened, and the surface shape of the mold is transferred to the optical glass. In this way, an optical glass lens can be obtained. The lens shape is not particularly limited, and examples thereof include a biconvex shape (for example, a spherical shape), a plano-convex shape, and a meniscus shape.

  For the purpose of improving the transmittance, an antireflection film may be formed on the surface of the optical glass lens.

  Next, an embodiment of a lens cap using the optical glass lens of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view showing a configuration of a lens cap.

  The lens cap 1 includes a metal shell 4 including a cylindrical side wall portion 2 and an end wall portion 3 provided at the tip of the side wall portion 2 and having a lens holding hole at the center thereof, and the metal shell 4. And an optical glass lens 6 sealed with a sealing material 5 in the lens holding hole.

  As the material of the metal shell 4, Hastelloy (registered trademark), Inconel (registered trademark), SUS, or the like can be used. Moreover, as the sealing material 5, low melting glass, an adhesive agent, solder, etc. can be used.

  Hereinafter, the optical glass of this invention is demonstrated in detail based on an Example.

  Tables 1 and 2 show examples (samples Nos. 1 to 15) and comparative examples (samples Nos. 16 and 17) of the present invention.

  Each sample was produced as follows.

  First, the glass raw material prepared so that it might become the composition of Table 1 and Table 2 was put into the platinum crucible, and it melted at 1300 degreeC for 2 hours, respectively. Next, the molten glass was poured onto a carbon plate, cooled and solidified, and then annealed to produce a glass block. Thereafter, grinding, polishing, and washing were performed to obtain an optical glass. Various characteristics of the sample thus obtained were evaluated. The results are shown in each table.

  The refractive index nd is indicated by a measured value at the d-line (wavelength: 587.6 nm) using a refractometer.

  The refractive index n1310 is indicated by a measured value at 1310 nm using a refractometer.

  The Abbe number νd uses the refractive index value of the d-line and the refractive index of the F-line (486.1 nm) of the hydrogen lamp and the C-line (656.3 nm) of the hydrogen lamp, and νd = [(nd−1 ) / (NF-nC)].

  The thermal expansion coefficient and glass transition point at 30 to 300 ° C. were measured with a thermal expansion measuring device (dilatometer).

  The internal transmittance is within a wavelength range of 200 to 800 nm for each polished sample having a thickness of 5 mm ± 0.1 mm and 10 mm ± 0.1 mm using a spectrophotometer (UV-3100 manufactured by Shimadzu Corporation). Then, the transmittance including the surface reflection loss was measured, and the internal transmittance at a wavelength of 450 nm was calculated from the obtained measurement value.

  The liquid phase viscosity was determined as follows. A sample crushed so as to have a particle size of 300 to 600 μm was placed in a platinum container and held in a temperature gradient furnace for 24 hours. The maximum temperature at which the interface crystals were precipitated on the bottom surface of the platinum container was defined as the liquidus temperature. The viscosity of the sample was measured, and the viscosity at the liquidus temperature was defined as the liquidus viscosity.

As is apparent from the table, No. 1 as an example of the present invention. Samples 1 to 15 have a refractive index nd of 1.69 to 1.79, a refractive index n1310 of 1.67 to 1.75, an Abbe number of 24 to 31 and a thermal expansion coefficient of 121 to 30 at 30 to 300 ° C. It was 152 * 10 < ^-7 > / ^degreeC . The glass transition point is 410 to 470 ° C., the liquidus viscosity of ^10~10 2.5 dPa · s. On the other hand, No. which is a comparative example. It was found that the sample No. 16 had a high glass transition point of 551 ° C. and was inferior in press moldability. No. Sample No. 17 had a low liquidus viscosity of 10 ^0.3 dPa · s, was inferior in mass productivity, and could not be formed into droplets.

DESCRIPTION OF SYMBOLS 1 Lens cap 2 Side wall part 3 End wall part 4 Metal shell 5 Sealing material 6 Optical glass lens

Claims (14)

By _{mass%, P 2 O 5 25~40%} , SiO 2 + B 2 O 3 + Al 2 O 3 0~4%, ZnO 0~11%, Li 2 O 1.5~6%, Na 2 O 1~20 %, K ₂ O 0-7%, TiO ₂ 1-11%, Nb ₂ O ₅ 10-30%, Bi ₂ O ₃ 0-15%, WO ₃ 0-10% Glass.   Furthermore, it contains MgO + CaO + SrO + BaO 0-2% by mass%, The optical glass of Claim 1 characterized by the above-mentioned. The optical glass according to claim 1, further comprising 0 to 5% ZrO _{2 and} 0 to 5% La ₂ O ₃ by mass%. _PbO, As ₂ O _3, the optical glass according to claim 1, the GeO _2, characterized in that is substantially free.   The optical glass according to any one of claims 1 to 4, wherein a refractive index (nd) is 1.65 to 1.85.   Refractive index (n1310) is 1.64-1.84, Optical glass in any one of Claims 1-5 characterized by the above-mentioned.   Abbe number is 20-35, Optical glass in any one of Claims 1-6 characterized by the above-mentioned.   A glass transition point is 500 degrees C or less, The optical glass in any one of Claims 1-7 characterized by the above-mentioned. The optical glass according to any one of claims 1 to 8, wherein a coefficient of thermal expansion at 30 to 300 ° C is 110 × 10 ^-7 / ° C or more.   The optical glass according to any one of claims 1 to 9, wherein the internal transmittance at 450 nm is 98% or more.   Liquid phase viscosity is 10 dPa * s or more, The optical glass in any one of Claims 1-10 characterized by the above-mentioned.   It is an object for press molding, The optical glass in any one of Claims 1-11 characterized by the above-mentioned.   An optical glass lens comprising the optical glass according to claim 1.   A metal shell composed of a cylindrical side wall portion, an end wall portion provided at the tip of the side wall portion and having a lens holding hole at the center thereof, and sealed and fixed to the lens holding hole of the metal shell A lens cap comprising: the optical glass lens according to claim 13; and a sealing material for fixing the optical glass lens to a lens holding hole of a metal shell.