OPTICAL GLASS WITH HIGH REFRACTIVE INDEX

Abstract

An optical glass having the following oxides in mass percentage relative to a total mass of the optical glass: 10.0%-30.0% SiO.sub.2, 10.0%-30.0% P.sub.2O.sub.5, 0.1%-5.0% B.sub.2O.sub.3, 0.1%-10.0% Al.sub.2O.sub.3, 0.1%-10.0% Rn oxides, 1.0%-20.0% R oxides, 0.1%-5.0% ZrO.sub.2, 10.0%-30.0% TiO.sub.2, 15.0%-50.0% Nb.sub.2O.sub.5, 0.1%-10.0% Ln oxides, and 0.1%-10.0% WO.sub.3, wherein TiO.sub.2+Nb.sub.2O.sub.5+P.sub.2O.sub.5+the R oxides accounts for 60.01% or above.

Claims

1. An optical glass, comprising the following oxides in mass percentage relative to a total mass of the optical glass: 0%-30.0% SiO.sub.2, 10.0%-30.0% P.sub.2O.sub.5, 0.1%-5.0% B.sub.2O.sub.3, 0.1%-10.0% Al.sub.2O.sub.3, 0.1%-10.0% Rn oxides, 1.0%-20.0% R oxides, 0.1%-5.0% ZrO.sub.2, 10.0%-30.0% TiO.sub.2, 15.0%-50.0% Nb.sub.2O.sub.5, 0.1%-10.0% Ln oxides, and 0.1%-10.0% WO.sub.3, wherein TiO.sub.2+Nb.sub.2O.sub.5+P.sub.2O.sub.5+the R oxides accounts for 60.01% or above.

2. The optical glass of claim 1, wherein the R oxides comprise 3MgCO.sub.3, 4MgCO.sub.3, CaCO.sub.3, SrO.sub.2, BaCO.sub.3, and Ba(NO.sub.3).sub.2.

3. The optical glass of claim 1, wherein the Ln oxides comprise Y.sub.2O.sub.3, Gd.sub.2O.sub.3, and Yb.sub.2O.sub.3.

4. The optical glass of claim 1, wherein the optical glass has a refractive index (nd) between 1.80000 and 2.40000, a 80 of less than 430 nm, and an Abbe number (vd) between 15.0 and 25.0.

5. The optical glass of claim 1, wherein the optical glass has a weight per volume of between 2.90 g/cm.sup.3 and 3.00 g/cm.sup.3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0017] The composition and preparation method of the present invention are further described in detail below with reference to specific examples, but the present invention is not limited to the following embodiments and examples, and can be carried out with appropriate modifications within the scope of the objective of the present invention.

[0018] The present invention provides an optical glass with a high refractive index, which comprises the following oxides in mass percentage relative to a total mass of the optical glass:

[0019] 10.0%-30.0% SiO.sub.2, 10.0%-30.0% P.sub.2O.sub.5, 0.1%-5.0% B.sub.2O.sub.3, 0.1%-10.0% Al.sub.2O.sub.3, 0.1%-10.0% Rn oxides, 1.0%-20.0% R oxides, 0.1%-5.0% ZrO.sub.2, 10.0%-30.0% TiO.sub.2, 15.0%-50.0% Nb.sub.2O.sub.5, 0.1%-10.0% Ln oxides, and 0.1%-10.0% WO.sub.3, wherein TiO.sub.2+Nb.sub.2O.sub.5+P.sub.2O.sub.5+the R oxides accounts for 60.01% or above.

[0020] When each of SiO.sub.2 and P.sub.2O.sub.5 has a mass percentage of 10.0% or above, transmittance to short-wavelength visible light can be increased by reducing the coloration of the glass, and stable glass formation is facilitated to increase devitrification resistance of the glass. By controlling the mass percentage of SiO.sub.2 to 30.0% or less, a decrease in refractive index due to presence of the SiO.sub.2 can be suppressed, and thus a high refractive index can be obtained more easily. Therefore, in the present invention, among the equivalents of oxides making the optical glass, SiO.sub.2 has a mass percentage of preferably 30.0% or less, more preferably 29.5% or less, and most preferably 29.0% or less, relative to the total mass of the optical glass; in another aspect, among the equivalents of oxides making the optical glass, SiO.sub.2 has a mass percentage of preferably 10.0% or more, more preferably 15.0% or more, and most preferably 18.0% or more, relative to the total mass of the optical glass.

[0021] B.sub.2O.sub.3 is a component of the optical glass in the present invention, which facilitates stable glass formation to increase devitrification resistance. By controlling a mass percentage of B.sub.2O.sub.3 to 5.0% or less, a decrease in refractive index due to the presence of B.sub.2O.sub.3 can be suppressed, and thus a high refractive index can be obtained more easily. In the present invention, among the equivalents of oxides making the optical glass, B.sub.2O.sub.5 has a mass percentage of preferably 5.0% or less, more preferably 4.8% or less, and most preferably 4.6% or less, relative to the total mass of the optical glass. In another aspect, among the equivalents of oxides making the optical glass, B.sub.2O.sub.3 has a mass percentage of preferably 1.2% or more, more preferably 2.2% or more, and most preferably 3.3% or more, relative to the total mass of the optical glass.

[0022] Al.sub.2O.sub.3 is also a component of the optical glass in the present invention. When its mass percentage is 0.1% or more, the viscosity of the optical glass during melting can be increased and the chemical durability of the optical glass can be improved. In the present invention, when the mass percentage of Al.sub.2O.sub.3 is 10.0% or less, the melting property of the optical glass is improved and the devitrification tendency of the glass is reduced. In another aspect, among the equivalents of oxides making the optical glass, Al.sub.2O.sub.3 has a mass percentage of preferably 10.0% or less, more preferably 5.0% or less, and most preferably 3.0% or less, relative to the total mass of the optical glass.

[0023] When a total mass percentage of the Rn oxides is 10.0% or less, more preferably 9.0% or less, and most preferably 8.0% or less, a desired coloration in the present invention is obtained. In another aspect, a lowest possible total mass percentage of the Rn oxides is preferably 0.1% or more, more preferably 1.0% or more, and most preferably 2.0% or more.

[0024] When a total mass percentage of the R oxides is 1.0% or above, the stability of the glass can be improved. In particular, the R oxides function to inhibit the permeation of TiO.sub.2. In the present invention, the total mass percentage of the R oxides is preferably 8.0% or more, more preferably 10.0% or more, or 12.0% or more, and most preferably 15.0% or more. In another aspect, to prevent or least reduce a decrease in refractive index, the total mass percentage of the R oxides is preferably 20.0% or less, more preferably 19.5% or less, further preferably 19.0% or less, furthermore preferably 18.5% or less, and most preferably 18.0% or less.

[0025] ZrO.sub.2 is a component of the optical glass in the present invention. When a mass percentage of the ZrO.sub.2 is 0.1% or above, the coloration of the glass can be reduced, the transmittance to short-wave visible light can be increased, stable glass formation can be promoted, and the light transmittance of the glass can be increased. In another aspect, by controlling the mass percentage of the ZrO.sub.2 to 5.0% or less, devitrification due to excessive ZrO.sub.2 can be reduced. Therefore, among the equivalents of oxides making the optical glass, ZrO.sub.2 has a mass percentage of preferably 5.0% or less, more preferably 4.5% or less, and most preferably 4.0% or less, relative to the total mass of the optical glass. In another aspect, among the equivalents of oxides making the optical glass, ZrO.sub.2 has a mass percentage of preferably 1.0% or more, more preferably 2.0% or more, and most preferably 3.0% or more, relative to the total mass of the optical glass.

[0026] By controlling a mass percentage of the Ln oxides to 10.0% or less, devitrification due to excessive Ln oxides can be suppressed, and a gram to cm.sup.3 (g/cm.sup.3) of the optical glass can kept low. Therefore, a greatest possible mass percentage of the Ln oxides is preferably 10.0% or less, more preferably 8.0% or less, further preferably 6.0% or less, furthermore preferably 4.0% or less, and most preferably 1.0% or less.

[0027] A total amount of the TiO.sub.2, Nb.sub.2O.sub.5, P.sub.2O.sub.5, and the R oxides can be reduced to 90.0% or less to reduce the gram to cm.sup.3 (g/cm.sup.3) of the optical glass. Many components contributing to the high refractive index account for more amounts in the optical glass compared with other components. By suppressing the amounts of these components contributing to the high refractive index, the gram to cm.sup.3 (g/cm.sup.3) of the optical glass can be kept low so that an optical apparatus can be made as small and as light as possible. Therefore, the total mass of TiO.sub.2. Nb.sub.2O.sub.5, P.sub.2O.sub.5, and the R oxides is preferably 88.0% or less, more preferably 86.0% or less, and most preferably 84.0% or less. In another aspect, in terms of improving refractive index and dispersion, the total mass of TiO.sub.2. Nb.sub.2O.sub.5, P.sub.2O.sub.5, and the R oxides may be 60.01% or more.

[0028] WO.sub.3 is a component of the optical glass in the present invention. When the mass percentage of WO.sub.3 is 0.1% or more, the effect of improving the strength and elastic modulus of the optical glass is obtained. In particular, the mass percentage of WO.sub.3 can be reduced to 10.0% or less to improve the melting property of the optical glass and reduce the devitrification tendency of the optical glass. Therefore, among the equivalents of oxides making the optical glass, the mass percentage of WO.sub.3 is preferably 10.0% or less, more preferably 5.0% or less, and most preferably 3.0% or less, relative to the total mass of the optical glass.

[0029] Specifically, the Rn oxides comprise Li.sub.2CO.sub.3, LiNO.sub.3, Na.sub.2CO.sub.3, NaNO.sub.3, K.sub.2CO.sub.3, KNO.sub.3, RbO.sub.2, and Cs.sub.2O. In order to obtain the desired high refractive index according to the present invention, Li.sub.2CO.sub.3, K.sub.2CO.sub.3, and Na.sub.2CO.sub.3 of the Rn oxides can be involved in ion exchanges in a chemical strengthening process, in which Li.sub.2CO.sub.3, K.sub.2CO.sub.3, and Na.sub.2CO.sub.3 are the object exchange substances of (K+) and (Li+) during ion exchanges; Li.sub.2CO.sub.3, K.sub.2CO.sub.3, and Na.sub.2CO.sub.3 have an effect of reducing dissolution viscosity and prevent dissolution and devitrification (i.e. they are devitrification resistant components). However, too many of these components may results in deterioration in chemical durability and permeation resistance.

[0030] Specifically, the R oxides comprise 3MgCO.sub.3, 4MgCO.sub.3, CaCO.sub.3, SrO.sub.2, BaCO.sub.3, and Ba(NO.sub.3).sub.2.

[0031] Specifically, the Ln oxides comprise Y.sub.2O.sub.3, Gd.sub.2O.sub.3, and Yb.sub.2O.sub.3.

[0032] Specifically, the optical glass has a refractive index (nd) between 1.80000 and 2.40000, a 80 of less than 430 nm, and an Abbe number (vd) between 15.0 and 25.0.

[0033] Specifically, the optical glass has a gram to cm.sup.3 (g/cm.sup.3) of between 2.90 and 3.00.

[0034] A method for preparing the optical glass of the present invention, comprising the steps of: mixing raw materials evenly according to the above mentioned mass percentages of the oxides to obtain a mixture; in one embodiment, the mixing is carried out in a mixer for a period of 5-60 min, and the mixer rotates at a speed of 1.0-30 rpm; melting the mixture in a quartz crucible, a zircon crucible, or a platinum crucible to form a melted mixture at a melting temperature of 1500-1700 C. for a period of 2-72 h; and the melting temperature is reduced to 1000-1450 C. at a start of a subsequent cooling step of the melted mixture, and then the melted mixture is poured into a mold in which the cooling step is performed where the melted mixture is slowly cooled to produce a glass sheet.

[0035] The optical glass of the present invention can be melted and shaped by known methods. The particular method of forming the melted mixture shall not be limited to the method described herein.

[0036] The optical glass eventually produced can be further processed to form a molded glass body, for example, by grinding and/or molding such as a secondary heat press molding or precise press molding. In other words, the molded glass body may be produced by grinding and polishing and/or other processing methods of the optical glass. The processing methods for producing the molded glass body are not limited to the processing methods described herein.

[0037] The glass sheet can be further subject to a chemical strengthening process to form compressive stress layers, particularly comprising the following steps: The glass sheet is in contact with or soaked in a molten salt containing potassium or sodium, such as potassium nitrate (KNO.sub.3), sodium nitrate (NaNO.sub.3), a mixture thereof or a compound salt thereof, carried out in one, two, or three stages;

[0038] for example, in case of a two-stage treatment, in the first stage, the glass sheet is in contact with or soaked in a sodium salt or a mixed salt of potassium and sodium for 1-720 min, preferably 30-500 min; then in the second stage, the glass sheet already subject to the first stage processing is in contact with or soaked in a potassium salt or a mixed salt of potassium and sodium for 1-720 min, preferably 10-500 min; in case of one-stage treatment, the glass sheet is in contact with or soaked in a potassium salt, a sodium salt, or a mixed salt thereof for 1-1440 min, preferably 60-800 min;

[0039] next, heating the glass sheet already subject to the previous treatment to 300-600 C. and then rapid cooling it, such as by water-cooling and/or air-cooling, so that compressive stress layers can be formed through a temperature difference between a surface and an interior of the rapidly cooled glass sheet.

[0040] Alternatively, the glass sheet can be further subject to ion implantation process to form compressive stress layers, particularly comprising the following steps: ions are implanted into the surface of the glass sheet under accelerated energy and accelerated voltage through collision of any ions with the surface of the glass sheet without damaging the surface of the glass sheet; subsequently, heating and rapid cooling treatments as same as those described in the previous paragraph are carried out as needed to form the compressive stress layers on the surface of the glass sheet.

[0041] As shown in Table 1 below, the compositions of optical glasses according to some examples of the present invention, the composition of an optical glass according to a comparative example, and values of the refractive index (nd), Abbe number (vd), and g/cm.sup.3 of these optical glasses are shown and compared.

TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 Oxide SiO.sub.2 30.00 16.62 13.40 20.00 11.44 11.65 11.74 (mass P.sub.2O.sub.5 17.00 10.35 13.34 10.11 15.33 20.00 10.00 percentage B.sub.2O.sub.3 0.55 5.00 2.21 0.50 2.00 1.33 1.00 %) Al.sub.2O.sub.3 0.55 1.22 3.58 2.07 1.00 2.22 1.00 Li.sub.2CO.sub.3 0.50 1.00 1.80 0.88 0.20 0.64 0.20 LiNO.sub.3 0.24 0.25 0.12 0.55 0.10 0.11 0.10 Na.sub.2CO.sub.3 0.55 1.00 4.44 2.22 0.50 3.31 0.50 NaNO.sub.3 0.19 0.25 1.25 1.13 1.20 1.11 1.20 K.sub.2CO.sub.3 0.34 0.75 1.00 1.14 4.44 1.33 4.44 KNO.sub.3 0.40 0.50 0.50 0.22 1.00 0.88 1.00 RbO.sub.2 0.74 1.00 0.44 0.11 1.00 0.33 1.00 Cs.sub.2O 0.74 0.25 0.45 0.55 1.00 0.11 1.00 3MgCO.sub.3 2.21 0.55 8.00 4.44 5.01 8.00 12.00 4MgCO.sub.3 1.00 0.50 0.53 0.50 0.50 1.00 0.50 CaCO.sub.3 1.00 1.33 2.04 0.50 1.00 1.00 1.75 SrO.sub.2 2.00 0.88 2.44 2.22 0.40 0.50 3.50 BaCO.sub.3 8.88 2.00 1.00 2.00 0.40 0.50 1.75 Ba(NO.sub.3).sub.2 3.11 1.22 1.00 2.00 0.30 0.50 0.50 ZrO.sub.2 1.40 1.00 0.80 1.00 5.00 4.22 1.00 TiO.sub.2 10.17 22.22 18.82 22.77 20.44 18.34 24.99 Nb.sub.2O.sub.5 15.33 20.78 20.33 23.44 25.44 18.99 18.33 Gd.sub.2O.sub.3 1.00 2.87 0.66 0.33 0.50 1.33 0.50 Yb.sub.2O.sub.3 1.00 5.88 0.66 0.66 0.50 0.30 0.50 Y.sub.2O.sub.3 1.00 1.25 0.55 0.33 1.00 0.30 1.00 WO.sub.3 0.12 1.33 0.64 0.33 0.30 2.00 0.50 ZnO La.sub.2O.sub.3 Sb.sub.2O.sub.3 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Rn.sub.2O (mass percentage %) 3.68 5.00 10.00 6.80 9.44 7.82 9.44 Ln.sub.2O.sub.3 (mass percentage %) 3.00 10.00 1.87 1.32 2.00 1.93 2.00 RO (mass percentage %) 18.20 6.48 15.01 11.66 7.61 11.50 20.00 TiO.sub.2 + Nb.sub.2O.sub.5 + P.sub.2O.sub.5 + RO 60.70 59.83 67.50 67.98 68.82 68.83 73.32 (mass percentage %) Optical Refractive 1.98868 2.16558 2.11124 1.94444 2.28033 2.04432 2.07643 Glass With Index (nd) High Abbe 22.34 16.33 17.23 22.67 16.32 22.11 22.06 Refractive number (vd) Index Weight per 2.90 2.92 2.96 2.91 2.94 2.98 2.93 volume (g/cm.sup.3) Optical Surface 933.1 733.7 886.9 968.9 345.8 689.9 444.4 Glass With compressive High stress - CS Refractive (Mpa) Index and Depth of 51.5 97.6 56.7 78.8 12.7 88.6 7.7 High Layers Strength DOL(m) in compressive stress Comparative Eample 8 9 10 11 12 13 14 15 example Oxide SiO.sub.2 10.35 12.66 12.14 10.08 11.26 13.62 10.16 13.11 14.00 (mass P.sub.2O.sub.5 10.66 12.22 15.24 12.44 16.66 11.11 12.22 10.33 percentage %) B.sub.2O.sub.3 4.00 2.22 1.33 2.00 12.22 1.11 0.40 1.11 24.00 Al.sub.2O.sub.3 5.11 10.00 4.44 2.00 1.88 2.22 1.22 1.11 Li.sub.2CO.sub.3 1.00 0.20 1.33 0.64 1.33 0.64 0.40 0.44 LiNO.sub.3 0.50 0.10 0.50 0.11 0.50 0.11 0.11 0.10 Na.sub.2CO.sub.3 4.00 0.50 4.44 4.44 4.44 3.31 4.44 0.50 NaNO.sub.3 1.11 1.20 0.50 1.11 0.50 1.11 2.22 1.20 K.sub.2CO.sub.3 1.33 4.44 1.33 1.33 1.33 1.33 1.33 2.22 KNO.sub.3 0.50 1.00 0.44 0.88 0.44 0.88 0.50 1.00 RbO.sub.2 0.50 1.00 0.44 0.44 0.44 0.33 0.50 1.00 Cs.sub.2O 1.00 1.00 0.33 0.50 0.22 0.11 0.50 1.00 3MgCO.sub.3 6.00 4.00 2.44 10.00 4.00 2.00 4.44 2.66 4MgCO.sub.3 2.00 0.50 1.00 1.00 1.00 1.11 1.11 0.50 CaCO.sub.3 1.00 2.00 2.44 1.00 4.00 2.00 1.11 0.50 6.00 SrO.sub.2 1.00 2.00 2.33 1.11 1.00 2.00 1.00 1.88 BaCO.sub.3 1.00 2.00 2.24 1.11 1.00 1.00 1.00 1.88 10.00 Ba(NO.sub.3).sub.2 0.50 1.00 0.33 1.11 0.50 1.11 0.55 0.50 ZrO.sub.2 2.44 2.22 0.66 4.22 4.66 0.55 1.11 4.22 6.00 TiO.sub.2 11.12 18.60 18.55 18.11 12.44 10.70 25.55 25.00 23.00 Nb.sub.2O.sub.5 28.88 16.66 17.22 14.66 24.66 40.00 16.11 24.98 2.00 Gd.sub.2O.sub.3 3.00 1.00 1.00 2.00 0.66 0.88 2.55 1.22 Yb.sub.2O.sub.3 1.00 1.00 1.00 5.00 1.00 0.66 0.22 1.22 Y.sub.2O.sub.3 1.00 0.32 5.00 1.00 1.00 1.00 1.25 0.64 WO.sub.3 1.00 2.16 3.33 3.71 2.86 1.11 10.00 1.68 ZnO 1.00 La.sub.2O.sub.3 13.90 Sb.sub.2O.sub.3 0.10 Total 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 Rn.sub.2O (mass percentage %) 9.94 9.94 9.31 9.45 9.20 7.82 10.00 7.46 0.00 Ln.sub.2O.sub.3 (mass percentage %) 5.00 2.32 7.00 8.00 2.66 2.54 4.02 3.08 0.00 RO (mass percentage %) 11.50 11.50 10.78 15.33 11.50 9.22 9.21 7.92 16.00 TiO.sub.2 + Nb.sub.2O.sub.5 + P.sub.2O.sub.5 + RO 62.16 58.98 61.79 60.54 65.26 71.03 63.09 68.23 41.00 (mass percentage %) Optical Glass Refractive Index 2.36442 2.33211 2.38964 2.14643 2.18656 2.23645 1.99783 2.40343 1.91 With High (nd) Refractive Abbe number (vd) 15.68 15.99 15.23 17.22 16.13 16.79 22.66 15.01 Index Weight per 2.96 2.98 2.99 2.98 2.99 2.96 2.93 2.99 4.50 volume (g/cm.sup.3) Optical Glass Surface 833.7 225.8 899.9 944.3 657.9 722.3 788.5 845.8 With High compressive Refractive stress - CS (Mpa) Index and Depth of Layers 44.6 5.6 44.4 88.6 45.1 86.3 66.8 23.6 High Strength DOL(m) in compressive stress

[0042] The refractive index (nd) and the Abbe number (vd) of the optical glasses in the examples and the comparative example were determined according to the V-block method specified in JISB7071-2:2018. Here, the refractive index (nd) was determined for a d line (587.56 nm) of a helium lamp. The Abbe number (vd) was calculated by using the values of the refractive index (nd) of the d line of the helium lamp, a refractive index (n.sub.F) of an F line (486.13 nm) of a hydrogen lamp, a refractive index (n.sub.C) of a C line (656.27 nm) of the hydrogen lamp, and the numerical formula for Abbe number (vd)=[(nd1)/(n.sub.Fn.sub.C)]. The refractive index (nd) and the Abbe number (vd) were determined by testing a glass obtained at a slow cooling of a temperature-decreasing speed of 25 C./hr.

[0043] The weight per volume (g/cm.sup.3) of the optical glasses in the examples was determined based on the method of measuring density and weight per volume by hydrostatic weighing method according to JISZ8807:2012.

[0044] The surface compressive stress (CS) and the total thickness of the compressive stress layers (depth of layer DOL) were determined by using a FSM-6000LE series glass surface stress meter manufactured by ORIHARA. A light source with a wavelength of 596 nm was selected as a light source for the measuring machine used in the CS test. The refractive index value at the wavelength of 596 nm was calculated from the refractive index measurement values at the wavelengths of C, d, F and g lines by second-order approximation according to the V-block method specified in JISB7071-2:2018.

[0045] It can be concluded from the above table that all the crystallized optical glasses obtained by the examples of the present invention meet the requirements of CS being 225.8-968.9 Mpa and DOL of 5.6-97.6 m. Accordingly, they can all achieve the technical effects of increasing the surface compressive stress of the compressive stress layers while reducing the central compressive stress, and having strong impact resistance, meaning that even if the glasses are impacted and thus damaged, they are not easy to be broken into shattered fragments.

[0046] The above description merely describes the preferred embodiments of the present invention, and is not intended to limit the present invention in any form. The protection scope of the present invention shall be defined by the protection scope of the claims. Although the preferred embodiments of the present invention are disclosed above, the embodiments are not intended to limit the present invention. Any of those skilled in the art may make some changes or modifications according to the above disclosure to obtain embodiments of equivalent technical effects without departing from the scope of the technical solutions of the present invention. Any simple amendment, equivalent variations, and modification made based on the above embodiments according to the technical essence of the present invention without departing from the teachings of the technical solutions of the present invention shall fall within the scope of the technical solutions of the present invention.