WO2018051754A1

WO2018051754A1 - Tempered lens and method for manufacturing tempered lens

Info

Publication number: WO2018051754A1
Application number: PCT/JP2017/030245
Authority: WO
Inventors: 長嶋　達雄; 茂輝澤村; 周作秋葉; 伸一安間
Original assignee: 旭硝子株式会社
Priority date: 2016-09-14
Filing date: 2017-08-24
Publication date: 2018-03-22

Abstract

Provided is a tempered lens having high impact resistance. Also provided is a method for manufacturing a tempered lens having high impact resistance, wherein a chemical tempering treatment does not significantly change the shape of the lens. The tempered lens is a chemically tempered lens of a lens molded body of a glass, wherein the glass contains 30-65 mol% of SiO₂, 10 mol% or more of Li₂O, and 0-10 mol% of SrO+BaO, and Li₂O/(Li₂O+Na₂O+K₂O) is at least 0.5. The method for manufacturing a tempered lens comprises the steps of: molding a glass having the above composition into a lens molded body; and performing a chemical tempering treatment, under conditions satisfying a predetermined treatment temperature and treatment time, on the lens molded body by using a tempered molten salt containing at least sodium nitrate, the tempered molten salt containing 25 mass% or more of sodium nitrate and 95 mass% or more total of sodium nitrate and potassium nitrate.

Description

Reinforcement lens and method for manufacturing the reinforcement lens

The present invention relates to a reinforced lens, and more particularly to a reinforced lens having a high impact strength and a method for manufacturing the reinforced lens.

Conventionally, an imaging glass lens having a small and wide imaging angle of view has been used for applications such as an in-vehicle camera, a robot vision sensor, a surveillance camera, and a wearable camera.

In addition, since automobiles, robots, and surveillance cameras are assumed to move at high speeds or be used in harsh environments, an imaging glass lens mounted on an in-vehicle camera or the like is more than an imaging lens of a general camera. It is necessary to have extremely high strength. For example, an in-vehicle camera is required not to cause damage or erosion due to impact or wind pressure associated with traveling of an automobile or sand dust splashed by traveling. Furthermore, it is also important that there is little surface degradation or alteration due to chemicals such as acid rain, detergents and waxes used in car washing.

In the case of wearable cameras, it is assumed that the user accidentally drops or wipes dirt such as sebum and sand dust, so high impact resistance and mechanical strength are required, similar to in-vehicle camera lenses.

In order to obtain such high impact resistance and mechanical strength, a lens subjected to chemical strengthening treatment is disclosed. (For example, refer to Patent Document 1).

JP 2000-226227 A

However, the lens thus chemically strengthened deforms due to the formation of a compressive stress layer, and when incorporated in the imaging optical system of the camera, the image formation in the peripheral part away from the optical axis is shifted. There was a problem that the image quality deteriorated.

The present invention has been made from the above viewpoint, and an object thereof is to provide a reinforced lens having high impact resistance. It is another object of the present invention to provide a method for manufacturing a reinforced lens having high impact resistance, in which the shape does not change greatly even when chemically strengthened.

The present invention is a chemically strengthened lens of a glass lens molded body, wherein the glass contains 30 to 65 mol% of SiO ₂ , 10 mol% or more of Li ₂ O, 0 to 10 mol% of SrO + BaO, and Li ₂ O. A reinforced lens having / (Li ₂ O + Na ₂ O + K ₂ O) of 0.5 or more is provided.

In the reinforced lens of the present invention, when a 64.6 g iron ball is dropped toward the center of the reinforced lens placed on a horizontal plane, the falling ball strength indicated as a height at which the reinforced lens does not break is 80 cm or more. It is preferable that

In the reinforced lens of the present invention, the lens molding has a first main surface and a second main surface facing each other, the lens molding has a diameter of 14 mm, a radius of curvature of the first main surface of 12 mm, and The amount of change in the radius of curvature of the first main surface before and after chemical strengthening when the second main surface is molded to a radius of curvature of 3 mm is preferably 10 μm or less.

The reinforced lens of the present invention preferably has a crack initiation load (CIL) of 100 gf or more.
In the reinforced lens of the present invention, the glass preferably has a glass transition point (Tg) of 500 ° C. to 630 ° C.
The reinforced lens of the present invention preferably has a refractive index (nd) of 1.73 to 2.10 and an Abbe number (νd) of 15 to 45.
The reinforced lens of the present invention preferably has a refractive index (nd) of 1.63 or more and less than 1.73 and an Abbe number (νd) of 35 to 55.
The reinforced lens of the present invention preferably has a refractive index (nd) of 1.50 or more and less than 1.63 and an Abbe number (νd) of 45 to 65.

The reinforced lens of the present invention preferably has a water resistance of grade 3 or higher and an acid resistance of grade 3 or higher as measured according to JOGIS06-2008 according to the Japan Optical Glass Industry Association standard.
The reinforced lens of the present invention preferably includes an antireflection layer on at least one main surface of the first main surface and the second main surface.
The reinforced lens of the present invention preferably includes an antifouling coating layer on at least one main surface of the first main surface and the second main surface.

The present invention contains 30 to 65 mol% of SiO ₂ , 10 mol% or more of Li ₂ O, 0 to 10 mol% of SrO + BaO, and Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) is 0.5 or more. Mold glass into a lens molding,
The lens molded body is a reinforced molten salt containing at least sodium nitrate, and the reinforced molten salt contains 25% or more of sodium nitrate in terms of mass%, and contains 95% or more of sodium nitrate and potassium nitrate in total. Is used to provide a method for manufacturing a reinforced lens that is chemically strengthened under conditions satisfying the following formula (1), where T (unit: ° C.) is the chemical strengthening temperature and t (unit: time) is the processing time. To do.
30000 <T ^1.8 × t ^0.5 <50000 Formula (1)

According to the present invention, a reinforced lens having excellent impact resistance can be provided. In addition, according to the present invention, in a method for manufacturing a reinforced lens having high impact resistance, it is possible to provide a manufacturing method in which the shape does not change greatly even if chemical strengthening treatment is performed. The reinforced lens of the present invention has a strength that can sufficiently withstand a harsh usage environment without deteriorating the image quality when used for an imaging lens of a vehicle-mounted camera, for example.

It is sectional drawing of an example of the reinforced lens of embodiment of this invention. It is the schematic which shows the method of evaluating the falling ball intensity | strength of a reinforced lens in this invention.

Hereinafter, embodiments of the present invention will be described.
[Strengthened lens]
The strengthening lens of the present invention is a chemically strengthened lens of a glass lens molded body, wherein the glass contains 30 to 65 mol% of SiO ₂ , 10 mol% or more of Li ₂ O, 0 to 10 mol% of SrO + BaO, and _{_{_{Li 2 O / (Li 2 O}}} + Na 2 O + K 2 O) is 0.5 or more.

The reinforced lens of the present invention is obtained by using glass having the above-mentioned predetermined composition as a lens molded body, and chemically strengthening the lens molded body. In the reinforced lens of the present invention thus obtained, shape correction is basically not performed after the chemical strengthening process. Therefore, in the chemical strengthening treatment, sufficient impact resistance and mechanical characteristics must be obtained under the condition that the lens shape of the lens molded body obtained by molding does not change greatly. Details of a method of using glass as a lens molded body and a method of chemically strengthening the lens molded body will be described later.

The reinforced lens of the present invention is suitably used as a lens disposed on the most object side of an imaging lens such as an in-vehicle camera that requires sufficient strength, for example. An imaging lens such as a vehicle-mounted camera usually has a configuration in which a plurality of lenses are arranged so as to intersect the optical axis from the subject side toward the imaging element. Since lenses other than the lens arranged closest to the subject (hereinafter referred to as “other lenses”) are not directly exposed to the outside, the required intensity is smaller than the lens arranged closest to the subject.

The shape of the reinforced lens in the present invention is not particularly limited, and is appropriately selected according to the device used and the application. FIG. 1 is a cross-sectional view of an example of a reinforced lens according to an embodiment of the present invention. A reinforced lens 10 shown in FIG. 1 is a typical example of a lens disposed on the most object side of a vehicle-mounted camera. The strengthening lens 10 has a first main surface 1 disposed on the subject side and a second main surface 2 facing the first main surface 1. The first main surface 1 is a curved surface having a convex shape on the subject side, and the radius of curvature is R1. The diameter of the reinforced lens 10 is D1. The second main surface 2 has a convex curved surface on the subject side having a diameter D2 at the center, and the radius of curvature of the curved surface is R2. In the reinforced lens 10 shown in FIG. 1, the thickness of the convex portion is T1, and the distance between the apex of the curved surface of the second main surface 2 and the base portion is indicated by T2. The thickness of the reinforced lens 10 is T1 + T2.

The specific size of the reinforced lens 10 is, for example, a diameter D1 of the reinforced lens 10 of 5 to 50 mm, a radius of curvature R1 of the first main surface 1 of 5 to 500 mm, and a diameter of a curved surface of the second main surface 2. D2 is 2 to 40 mm, its radius of curvature R2 is 2 to 400 mm, the thickness T1 of the convex part is 0.1 to 10 mm, and the distance T2 between the vertex of the curved surface of the second main surface 2 and the base is 1 to 19 mm, strengthening The thickness of the lens 10 is 2 to 20 mm. In the following description, the curvature radius R2 of the curved surface of the second main surface 2 is referred to as the curvature radius R2 of the second main surface 2.

Note that the reinforced lens of the present invention is not limited to the reinforced lens having the cross-sectional shape shown in FIG. The reinforced lens of the present invention is a plano-convex reinforced lens mainly for convex lenses, having a curved surface on the first main surface disposed on the subject side, and a second main surface having a planar shape. Also good.

In order to obtain a reinforced lens having such a shape, the present invention obtains a molded lens by molding glass into a predetermined shape, and has sufficient impact resistance even under chemical strengthening conditions in which the shape does not change greatly. A chemical strengthening treatment can be performed so as to obtain mechanical properties.

As a result of intensive studies to solve the above problems, the present inventors have found that SiO ₂ is contained in an amount of 30 to 65 mol%, Li ₂ O is contained in an amount of 10 mol% or more, SrO + BaO is contained in an amount of 0 to 10 mol%, and Li ₂ O / It is found that the above-mentioned problem can be solved by molding glass having a (Li ₂ O + Na ₂ O + K ₂ O) of 0.5 or more into a lens molded body and subjecting the lens molded body to chemical strengthening treatment under predetermined conditions. The invention has been completed. In the present specification,% when referring to the composition of glass is mol% based on oxide unless otherwise specified.

(I) In general, chemical strengthening treatment in a glass molded body is performed by replacing alkali ions having a small ion radius with alkali ions having a large ion radius, so that a compression stress layer (hereinafter referred to as “strengthening layer”) is formed on the surface of the molded body. Is formed, and the impact resistance and mechanical properties are enhanced. Alkali ions have larger ionic radii in the order of Li ⁺ , Na ⁺ and K ⁺ , and in the chemical strengthening treatment, Li ⁺ is exchanged with Na ⁺ or K ⁺ , or Na ⁺ is exchanged with K ⁺ , The exchange speed is clearly faster in the former.

When a glass molding having a three-dimensional structure, such as a lens molding, having an asymmetric shape in the cross-sectional direction is chemically strengthened, the shape changes as the chemical strengthening time increases and the processing temperature increases. It becomes easy. Further, it was found that even when the chemical strengthening treatment is performed under the same conditions, the shape change is large when Na ⁺ is replaced with K ⁺ . In the present invention, the glass contains 10 mol% or more of Li ₂ O because sufficient impact resistance and mechanical properties can be obtained under chemical strengthening conditions in which the lens shape obtained by molding does not change significantly. In order to make the chemical strengthening treatment efficient, Li ₂ O is preferably 12% or more, and more preferably 15% or more. Further, from the viewpoint of suppressing stress relaxation in chemically strengthened glass due to devitrification and Tg reduction, Li ₂ O in the glass is preferably 30% or less, and more preferably 25% or less.

(II) In the glass constituting the lens molding, the ratio of Li ₂ O content to the total content of alkali metal components (Li ₂ O + Na ₂ O + K ₂ O), Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) Is 0.5 or more. By setting Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) to 0.5 or more, the efficiency with which Li ⁺ is exchanged with Na ⁺ or K ⁺ can be increased. The ratio is more preferably 0.6 or more, and further preferably 0.7 or more.

(III) In the glass constituting the lens molding, SrO + BaO is 10 mol% or less. SrO and BaO are components that impair the impact resistance and mechanical properties that inhibit the chemical strengthening treatment and increase the specific gravity of the glass. More preferably, it is 8% or less, More preferably, it is 6% or less. SrO and BaO are preferably not included from the viewpoint of impact resistance and mechanical properties, but this purpose is lost for reasons such as increasing the Abbe number, increasing the refractive index, and improving the thermal stability of the glass. You may make it contain in the range which is not.

(IV) In the glass, SiO ₂ is contained in the range of 30 to 65 mol%. SiO ₂ is a glass network former, and if it is less than 30%, impact resistance and mechanical properties deteriorate. Preferably it is 35% or more, more preferably 40% or more. If it exceeds 65%, Tg becomes too high and chemical strengthening treatment cannot be carried out efficiently, and the melting temperature rises and productivity may be impaired. Preferably it is 62% or less, More preferably, it is 60% or less.

The reinforced lens of the present invention obtained by molding glass having the above composition into a lens molded body and chemically strengthening it preferably has the following impact resistance. The falling ball strength was used as an index of impact resistance in the present invention. FIG. 2 shows a schematic diagram of the falling ball strength test.

The falling ball strength in the present invention means, for example, a height that does not break even if a 64.6 g iron ball 12 is dropped on the center C of the reinforced lens 10 placed on the horizontal surface 11 as shown in FIG. The test starts from a height of 10 cm (h), and if it is not broken, it is raised by 10 cm. When the reinforced lens is broken or cracked, the test is terminated and the height (h) immediately before breaking. Was the falling ball strength.

The reinforced lens of the present invention preferably has a falling ball strength of 80 cm or more (corresponding to 0.5 J). The strengthening lens used for the drop-ball strength test has a predetermined shape, that is, in the strengthening lens shown in FIG. 1, the diameter D1 of the strengthening lens 10 is 14 mm, the radius of curvature R1 on the first principal surface 1 is 12 mm, and the second principal The curved surface diameter D2 of the surface 2 is 5.72 mm, the curvature radius R2 thereof is 3 mm, the convex portion thickness T1 is 1.4 mm, and the distance T2 between the vertex of the curved surface of the second main surface 2 and the base portion is 2. The test reinforced lens is 1 mm, and the thickness of the reinforced lens 10 is 3.5 mm.

In the reinforced lens of the present invention obtained by molding glass having the above composition into a lens molded body and chemically strengthening it, it is preferable that the lens shape change before and after chemical strengthening is in the following range. The lens shape change before and after chemical strengthening can be measured, for example, by the following method.

The lens molded body has a first main surface and a second main surface facing each other, and is molded into a diameter of 14 mm, a radius of curvature of 12 mm of the first main surface, and a radius of curvature of 3 mm of the second main surface. The amount of change in the radius of curvature of the first main surface before and after chemical strengthening is measured. More specifically, the shape of the molded lens used for the chemical strengthening treatment is the same as the shape of the strengthened lens used for the falling ball test.

The radius of curvature of the first principal surface of the lens molded body and the reinforced lens obtained by chemical strengthening treatment can be measured, for example, with a 3D measuring device (manufactured by KEYENCE, VR-3200). In addition, as conditions for the chemical strengthening treatment in the test, for example, using a strengthened molten salt containing 25% by mass of sodium nitrate and 75% by mass of potassium nitrate with respect to the total amount of the strengthened molten salt, Conditions are mentioned.

In the reinforced lens of the present invention, it is preferable that the amount of change in the radius of curvature on the first main surface before and after the chemical tempering treatment is 10 μm or less as evaluated in this way. When the amount of change in the radius of curvature on the first main surface exceeds 10 μm, if the shape correction by polishing or the like is not performed after the chemical strengthening process, the image is formed particularly in the peripheral part away from the optical axis when incorporated in the imaging optical system of the camera. May shift and the image quality may deteriorate. Further, when polishing is performed for shape correction, the reinforcing layer obtained by the chemical strengthening treatment is lost, and it may be impossible to expect improvement in impact resistance and mechanical properties. The amount of change in the radius of curvature on the first main surface before and after the chemical strengthening treatment is preferably 5 μm or less, more preferably 3 μm or less, and particularly preferably 1 μm or less.

Furthermore, as an index of strength in the reinforced lens of the present invention, the load of the Vickers indenter at which the occurrence rate of cracks when the indentation is formed using the Vickers indenter is 50% (this load is referred to as crack initiation load (CIL)). ) Can be used.

CIL is an index of crack resistance, and the larger the CIL, the less likely it is to crack. The CIL of the reinforced lens of the present invention is preferably 100 gf or more, more preferably 200 gf or more, and further preferably 300 gf or more.

In the present specification, the CIL value of the reinforced lens of the present invention refers to the CIL value in an evaluation sample obtained by molding the glass used for the reinforced lens into a plate shape and chemically strengthened, obtained by the following method. .

A Vickers hardness tester was used to push the Vickers indenter for 15 seconds on the surface of the evaluation sample that had been mirror-polished on both sides of a 2 mm thick glass plate and then removed the Vickers indenter. Observe. An average value of the number of cracks generated with respect to the indentation load of the Vickers indenter of 100 gf, 200 gf, 300 gf, 500 gf, 1000 gf, and 2000 gf is calculated for each load. The relationship between the load and the number of cracks is calculated by regression using a sigmoid function. From the regression calculation result, the load at which the number of cracks is two can be used as the CIL (gf) of the sample for evaluation. The occurrence rate is 100% when a total of four cracks are generated from all four corners of the indentation.

Compressive stress (CS) of the reinforcing layer in the reinforced lens of the present invention is preferably 50 MPa or more, more preferably 100 MPa or more, and further preferably 150 MPa or more.

The depth of the reinforcing layer (DOL; Depth of layer) in the reinforced lens of the present invention is preferably 5 μm or more from the surface. More preferably, it is 10 micrometers or more, More preferably, it is 20 micrometers or more. Considering the shape of the reinforced lens, the thickness of the reinforced layer is preferably 500 μm or less. The thickness of the reinforcing layer is more preferably 300 μm or less, and further preferably 200 μm or less. The CS and DOL of the reinforced lens in the present invention are preferably measured at the central portion of the first main surface of the reinforced lens.

CS and DOL, for example, measure the retardation of the surface compressive stress layer by passing light through the reinforcing layer on the cross section of the reinforced lens using a birefringence imaging system Abrio (manufactured by Tokyo Instruments), and use the photoelastic constant of the glass. Can be calculated.

The reinforced lens of the present invention has a water resistance (RW) of grade 3 or higher measured according to the “Optical Glass Chemical Durability Measurement Method (Powder Method)” (JOGIS06-2008) according to the Japan Optical Glass Industry Association Standard. The acid resistance (RA) is preferably grade 3 or higher. In the reinforced lens of the present invention, the RW and RA of the reinforced layer and the RW and RA of the glass inside the reinforced lens are strictly different, but in the present invention, there is no great difference that the grade is different. In the invention, both are treated as substantially the same.

Specifically, RW is measured as follows. For a glass powder having a diameter of 420 to 600 μm, a mass reduction rate (%) when immersed in 80 mL of pure water at 100 ° C. for 1 hour is measured. A predetermined grade is given according to the mass reduction rate. The smaller the numerical value, the better the RW. In the reinforced lens of the present invention, RW is more preferably grade 2 or more, and 1 is particularly preferred.

Specifically, RA is measured as follows. For a glass powder having a diameter of 420 to 600 μm, a mass reduction ratio (%) when immersed in 80 mL of a 0.01 N nitric acid aqueous solution at 100 ° C. for 1 hour is measured. A predetermined grade is given according to the mass reduction rate. The smaller the numerical value, the better the RA. In the reinforced lens of the present invention, RA is more preferably grade 2 or more, and 1 is particularly preferred.

In the reinforced lens of the present invention, the glass preferably has a specific gravity of 4.0 g / cm ³ or less. In the reinforced lens of the present invention, the specific gravity of the reinforced layer and the specific gravity of the glass inside the reinforced lens are substantially the same at the first place after the decimal point and are treated as the same. Thereby, when it is set as a reinforced lens, a crack is hard to generate | occur | produce. Therefore, a high-strength reinforced lens that hardly causes cracks starting from cracks can be obtained. The specific gravity is preferably 3.7 g / cm ³ or less, and more preferably 3.5 g / cm ³ or less.

In the reinforced lens of the present invention, the glass preferably has a glass transition point (Tg) of 500 ° C. or higher and 630 ° C. or lower. In the reinforced lens of the present invention, the Tg of the reinforced layer and the Tg of the glass inside the reinforced lens are substantially the same and are treated as the same. When glass has a low Tg of 630 ° C. or lower, for example, moldability when producing a reinforced lens by precision press molding with high manufacturing efficiency (hereinafter simply referred to as “press molding”) is good. In addition, if Tg is too low, it is preferable that the temperature is 500 ° C. or higher because compression stress is likely to be relaxed in a reinforced lens having a reinforced layer. The Tg of the glass is preferably 520 to 600 ° C, more preferably 540 to 590 ° C. Tg can be measured by, for example, a thermal expansion method.

In the present invention, the Young's modulus refers to the Young's modulus of the glass inside the reinforced lens. The Young's modulus is preferably 80 GPa or more, more preferably 90 GPa or more, still more preferably 95 GPa or more, and still more preferably 100 GPa or more.

In the present invention, the refractive index (nd) and Abbe number (νd) of the reinforced lens mean the refractive index and Abbe number of the glass inside the reinforced lens. Strictly speaking, the refractive index of the reinforcing layer is different from the refractive index of the glass inside the reinforcing lens, but the numerical value is different to the third place after the decimal point. In the present invention, both are treated as substantially the same.

The reinforced lens in the present invention preferably has a refractive index of 1.50 to 2.10, and is divided into three cases according to the specification.
<Strengthened lens of the first specification>
The first type of reinforced lens uses a glass lens with a high Abbe number that can shoot a smaller and wider area and that other lenses placed closer to the image sensor can sufficiently correct chromatic aberration. It is a reinforced lens suitable when possible. The reinforced lens of the first specification preferably has a refractive index (nd) in the range of 1.73 to 2.10 and an Abbe number (νd) in the range of 15 to 45. More preferably, nd is in the range of 1.75 to 2.00 and νd is in the range of 20 to 43, and further preferably, nd is in the range of 1.77 to 1.90 and νd is in the range of 25 to 41.

<Strengthened lens of the second specification>
The reinforced lens of the second specification is a glass with a high Abbe number so that the lens arranged on the side closer to the imaging device can sufficiently correct chromatic aberration when photographing a wide range with high resolution and cost. This lens is a reinforced lens that cannot be used with a lens, and is suitable when a low-cost glass or resin lens is used. The reinforced lens of the second specification preferably has a refractive index (nd) of 1.63 or more and less than 1.73 and an Abbe number (νd) of 35 to 55. More preferably, nd is in the range of 1.65 to 1.72, and νd is in the range of 40 to 53, and further preferably, nd is in the range of 1.67 to 1.70, and νd is in the range of 45 to 51.

<Third specification reinforced lens>
The third type of reinforced lens is a reinforced lens that is suitable when high resolution is more important than the viewing angle, or when the lens placed closer to the image sensor can only be used from the viewpoint of cost. It is. The reinforced lens of the third specification preferably has a refractive index (nd) of 1.50 or more and less than 1.63 and an Abbe number (νd) of 45 to 65. More preferably, nd is in the range of 1.55 to 1.62 and νd is in the range of 50 to 63, and further preferably, nd is in the range of 1.57 to 1.61 and νd is in the range of 55 to 61.

In order for the refractive index of the reinforced lens of the present invention to be 1.50 to 2.10, the glass used for the reinforced lens of the present invention is further expressed in mol% on an oxide basis.
SiO ₂ : 30% to 65%,
Al ₂ O ₃ : 0% to 20%,
B ₂ O ₃ : 0% to 40%,
P ₂ O ₅ : 0% to 20%,
MgO: 0% to 20%,
CaO: 0% to 20%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO ₂ : 0% to 20%,
ZrO ₂ : 0% to 15%,
Li ₂ O + Na ₂ O + K ₂ O: 10% to 30%,
Li ₂ O: 10% to 30%,
Na ₂ O: 0% to 15%,
K ₂ O: 0% to 5%,
Nb ₂ O ₅ : 0% to 30%,
Ln ₂ O ₃ : 0% to 20%,
La ₂ O ₃ : 0% to 20%,
Y ₂ O ₃ : 0% to 20%,
Gd ₂ O ₃ : 0% to 20%,
Ta ₂ O ₅ : 0% to 20%,
WO ₃ : It is preferable to contain 0% to 20%.
_Ln 2 _{O 3} in the above _shows the _{_{_{La 2 O 3 + Y 2 O}}} 3 + Gd 2 O 3. The same applies to the following description.

In order for the refractive index of the reinforced lens of the first specification of the present invention to be 1.73 to 2.10, the glass used for the reinforced lens of the first specification of the present invention may further include mol% based on oxide. In the display,
SiO ₂ : 30% to 55%,
Al ₂ O ₃ : 0% to 5%,
B ₂ O ₃ : 0% to 40%,
P ₂ O ₅ : 0% to 20%,
MgO: 0% to 10%,
CaO: 0% to 10%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO ₂ : 0% to 20%,
ZrO ₂ : 0% to 15%,
Li ₂ O + Na ₂ O + K ₂ O: 10% to 30%,
Li ₂ O: 10% to 30%,
Na ₂ O: 0% to 15%,
K ₂ O: 0% to 5%,
Nb ₂ O ₅ : 0% to 30%,
Ln ₂ O ₃ : 0% to 20%,
La ₂ O ₃ : 0% to 20%,
Y ₂ O ₃ : 0% to 20%,
Gd ₂ O ₃ : 0% to 20%,
Ta ₂ O ₅ : 0% to 20%,
WO _3: 0% ~ 20%
It is preferable to contain.

In addition, in order for the refractive index of the reinforced lens of the second specification of the present invention to be 1.63 or more and less than 1.73, the glass used for the reinforced lens of the second specification of the present invention is further oxide-based. In mol% display
SiO ₂ : 30% to 60%,
Al ₂ O ₃ : 0% to 10%,
B ₂ O ₃ : 0% to 20%,
P ₂ O ₅ : 0% to 20%,
MgO: 0% to 20%,
CaO: 0% to 20%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO ₂ : 0% to 5%,
ZrO ₂ : 0% to 15%,
Li ₂ O + Na ₂ O + K ₂ O: 10% to 30%,
Li ₂ O: 10% to 30%,
Na ₂ O: 0% to 10%,
K ₂ O: 0% to 5%,
Nb ₂ O ₅ : 0% to 15%,
Ln ₂ O ₃ : 0% to 20%,
La ₂ O ₃ : 0% to 20%,
Y ₂ O ₃ : 0% to 10%
Gd ₂ O ₃ : 0% to 10%,
Ta ₂ O ₅ : 0% to 10%,
WO ₃ : 0% to 10%
_Contains, it is preferable _{_{_{_{SiO 2 + Al 2 O 3 +}}}} B 2 O 3 + P 2 O 5 is less than 65% to 30%. The glass used for the reinforced lens of the second specification preferably has B ₂ O ₃ / Li ₂ O of 0.75 or less, and more preferably 0.7 or less.

In addition, in order for the refractive index of the reinforced lens of the third specification of the present invention to be 1.50 or more and less than 1.63, the glass used for the reinforced lens of the third specification of the present invention is further oxide-based. In mol% display
SiO ₂ : 30% to 65%,
Al ₂ O ₃ : 0% to 20%,
B ₂ O ₃ : 0% to 40%,
P ₂ O ₅ : 0% to 20%,
MgO: 0% to 20%,
CaO: 0% to 20%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO ₂ : 0% to 5%,
ZrO ₂ : 0% to 10%,
Li ₂ O + Na ₂ O + K ₂ O: 10% to 25%,
Li ₂ O: 10% to 20%,
Na ₂ O: 0% to 10%,
K ₂ O: 0% to 5%,
Nb ₂ O ₅ : 0% to 10%,
Ln ₂ O ₃ : 0% to 10%,
La ₂ O ₃ : 0% to 10%,
Y ₂ O ₃ : 0% to 5%,
Gd ₂ O ₃ : 0% to 5%,
Ta ₂ O ₅ : 0% to 5%,
WO ₃ : 0% to 5%
_{_{_{_{Containing, SiO 2 + Al 2 O 3}}}} + B 2 O 3 + P 2 O 5 and is 65% and less than _80%, it is preferred _{_{TiO 2 + Nb 2 O 5 +}} WO 3 is 10% or less.

The glass used for the reinforced lenses of the first to third specifications will be described below. The glass used in the present invention is not limited to the composition of the glass used for the reinforced lenses of the first to third specifications as long as the obtained reinforced lens has the characteristics described above, but is preferably in the following range. . In each glass, “substantially does not contain” means that it is not contained except for inevitable impurities. The content of inevitable impurities is 0.1% or less in the present invention. Preferably it is 0.05% or less, More preferably, it is 0.02% or less.

<Glass used for reinforced lenses of the first specification>
Hereinafter, the composition of the glass used for the reinforced lens of the first specification will be described.
SiO ₂ is an essential component in a glass network former, and if it is less than 30%, impact resistance and mechanical properties are lowered. Preferably it is 35% or more, more preferably 40% or more. If it exceeds 55%, the refractive index may decrease. Preferably it is 54% or less, More preferably, it is 52% or less.

Al ₂ O ₃ is an optional component. Al ₂ O ₃ is a component that improves chemical durability and improves impact resistance and mechanical properties, but when Al ₂ O ₃ increases, the refractive index decreases, Tg increases too much, glass May be easily devitrified. Preferably it is 3% or less, More preferably, it is 2% or less.

B ₂ O ₃ is an optional component. B ₂ O ₃ is a component that lowers the Tg, improves the thermal stability of the glass, and improves impact resistance and mechanical properties. However, if the amount of B ₂ O ₃ is large, the refractive index decreases. There is a risk that chemical durability tends to decrease. Preferably it is 30% or less, more preferably 20% or less.

P ₂ O ₅ is an optional component. P ₂ O ₅ is a component that lowers the Tg and is a component for adjusting the Abbe number. However, if the amount of P ₂ O ₅ is large, the refractive index, impact resistance, and mechanical properties are likely to be lowered. Preferably it is 10% or less, More preferably, it is 4% or less, More preferably, it is 2% or less. Most preferably, P ₂ O ₅ is not substantially contained.

MgO is an optional component. MgO is a component that improves the meltability of glass, suppresses devitrification, and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, when the amount of MgO increases, devitrification is promoted. Preferably it is 5% or less, More preferably, it is 3% or less.

CaO is an optional component. CaO is a component that suppresses devitrification and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, when the amount of CaO is large, the chemical strengthening treatment is hindered, and the impact resistance and mechanical properties are likely to deteriorate. Therefore, when CaO is contained, it is preferably 5% or less, more preferably 3% or less.

SrO is an optional component. SrO is a component that suppresses devitrification and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, if the amount of SrO is large, the impact resistance and mechanical properties, which impede the chemical strengthening treatment and increase the specific gravity of the glass, are significantly reduced. Therefore, when SrO is contained, it is preferably 5% or less, more preferably 3% or less, and further preferably 2% or less. Most preferably, SrO is not substantially contained.

BaO is an optional component. BaO is a component that suppresses devitrification and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, when the amount of BaO is large, the impact resistance and mechanical properties that inhibit the chemical strengthening treatment and increase the specific gravity of the glass are remarkably lowered. Therefore, when BaO is contained, it is preferably 5% or less, more preferably 3% or less, and further preferably 2% or less. Most preferably, BaO is not substantially contained.

ZnO is an optional component that adjusts optical constants such as the Abbe number and refractive index of glass to improve mechanical properties. On the other hand, since it will become easy to devitrify when there is much quantity of ZnO, Preferably it is 15% or less, More preferably, it is 10% or less, More preferably, it is 5% or less.

TiO ₂ is an optional component, and can be expected to increase the refractive index of the glass and improve the mechanical properties. On the other hand, when TiO ₂ is too much, it is easy to be colored, the transmittance is lowered, and in order to reduce the Abbe number, it is preferably 10% or less, more preferably 5% or less, and further preferably 3% or less. When TiO ₂ is contained, it is preferably 0.5% or more, more preferably 1% or more, and further preferably 1.5% or more.

ZrO ₂ is an optional component, and is a component that increases the refractive index of the glass and increases the chemical durability of the glass. Inclusion of ZrO ₂ can be expected to improve mechanical properties. On the other hand, when there is too much ZrO ₂ , devitrification tends to occur, so it is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. When ZrO ₂ is contained, it is preferably 0.5% or more, more preferably 1% or more, and further preferably 2% or more.

Li ₂ O is an essential component and is contained at 10% or more. In order to make the chemical strengthening treatment efficient, Li ₂ O is preferably 12% or more, more preferably 15% or more. Further, from the viewpoint of suppressing stress relaxation in the chemically strengthened glass due to devitrification and a decrease in Tg, Li ₂ O in the glass is preferably 30% or less, more preferably 25% or less.

Na ₂ O is an optional component that suppresses devitrification, lowers Tg, and enhances the efficiency of replacement with K ⁺ when the strengthened molten salt is a mixed salt of sodium nitrate and potassium nitrate. If it is too high, impact resistance and mechanical properties are likely to deteriorate. Preferably it is 15% or less, More preferably, it is 10% or less. When Na ₂ O is contained, it is preferably 1.5% or more, more preferably 2% or more, and further preferably 2.5% or more.

K ₂ O is an optional component and is a component that improves the meltability of the glass and suppresses devitrification. However, if it is too much, impact resistance and mechanical properties are likely to deteriorate. Preferably it is 5% or less, More preferably, it is 3% or less.

The total content of alkali metal components (R ₂ O = Li ₂ O + Na ₂ O + K ₂ O) is 10 to 30%. If it exceeds 30%, Tg may decrease, and acid resistance and water resistance may decrease. Preferably it is 28% or less, More preferably, it is 25% or less. Further, Li ₂ O content relative to _{_{_{R 2 O Li 2 O / (}}} Li 2 O + Na 2 O + K 2 O) is 0.5 or more. By setting Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) to 0.5 or more, the efficiency with which Li ⁺ is exchanged with Na ⁺ or K ⁺ can be increased. 0.6 or more is more preferable, and 0.7 or more is more preferable.

Nb ₂ O ₅ is an optional component that increases the refractive index of glass and can be expected to improve impact resistance and mechanical properties. On the other hand, if Nb ₂ O ₅ is too much, it tends to be devitrified, and the transmittance is lowered. In order to reduce the Abbe number, it is preferably 30% or less, more preferably 25% or less, and further preferably 20% or less. is there. When Nb ₂ O ₅ is contained, it is preferably 5% or more, more preferably 7% or more, and further preferably 10% or more.

La ₂ O ₃ is an optional component. La ₂ O ₃ is a component that does not reduce the Abbe number for improving the refractive index of the glass, so it can be used for adjusting the optical constant, etc., but it is lost if the amount of La ₂ O ₃ is too large. It becomes easy to see through, the specific gravity increases, and the impact resistance and mechanical properties are lowered. Therefore, if containing _La 2 _{O 3,} preferably 20% or less, more preferably 15% or less.

Y ₂ O ₃ is an optional component. Y ₂ O ₃ is a component that improves the refractive index of glass and can be expected to improve mechanical properties. However, if the amount of Y ₂ O ₃ is too large, it tends to be devitrified. _Therefore, when they contain Y 2 _{O 3,} preferably 20% or less, more preferably 15% or less.

Gd ₂ O ₃ is an optional component. Gd ₂ O ₃ is a component that does not reduce the Abbe number for improving the refractive index of the glass, so it can be used for adjustment of the optical constant, etc., but it is lost if the amount of Gd ₂ O ₃ is too large. It becomes easy to see through, the specific gravity increases, and the impact resistance and mechanical properties are lowered. Therefore, if containing _Gd 2 _{O 3,} preferably 20% or less, more preferably 15% or less.

Ln ₂ O ₃ (Ln is at least one selected from the group consisting of Y, La, Gd, Yb, and Lu. That is, Ln ₂ O ₃ is La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ Is an optional component. Ln ₂ O ₃ is a component that improves the refractive index of the glass. However, if the amount of Ln ₂ O ₃ is too large, it tends to devitrify. Therefore, if containing _Ln 2 _{O 3,} preferably 20% or less, more preferably 15% or less.

Ta ₂ O ₅ is an optional component. Ta ₂ O ₅ is a component that improves the refractive index of the glass. However, if the amount of Ta ₂ O ₅ is too large, it tends to devitrify and the specific gravity also increases. Therefore, if containing _Ta 2 _{O 5,} preferably 20% or less, more preferably 15% or less.

WO ₃ is an optional component. WO ₃ is a component that improves the refractive index of the glass and improves the thermal stability of the glass. However, if the amount of WO ₃ is too large, it tends to devitrify, reduce the Abbe number, and increase the specific gravity. . Therefore, if containing WO _3, preferably 20% or less, more preferably 15% or less.

As other components, Bi ₂ O ₃ and TeO ₂ may be contained in less than 10%. These are not essential components, but can be expected to increase the refractive index and improve the meltability. When these components are contained, the total content is preferably 5% or less, and more preferably 3% or less.

Since As ₂ O ₃ is a harmful chemical substance, it tends to be refrained from use in recent years, and measures for environmental measures are required. Therefore, when importance is placed on the environmental impact, it is preferable that the substance is not substantially contained except for inevitable mixing.

Furthermore, it is preferable that at least one of Sb ₂ O ₃ and SnO ₂ is contained. These are not essential components, but can be added for the purpose of adjusting refractive index characteristics, improving meltability, suppressing coloring, improving transmittance, clarifying, and improving chemical durability. When these components are contained, the total content is preferably 1% or less, and more preferably 0.5% or less.

Furthermore, it is preferable that F is contained. Although F is not essential, it can be added for the purpose of improving meltability, improving transmittance, improving clarity, and the like. When F is contained, the content ratio is preferably 5% or less, and more preferably 3% or less.

<Glass used for reinforced lenses of the second specification>
Hereinafter, the composition of the glass used for the reinforced lens of the second specification will be described.
SiO ₂ is an essential component in a glass network former, and if it is less than 30%, impact resistance and mechanical properties are lowered. Preferably it is 35% or more, more preferably 40% or more. If it exceeds 60%, the refractive index may decrease. Preferably it is 58% or less, More preferably, it is 56% or less.

Al ₂ O ₃ is an optional component. Al ₂ O ₃ is a component that improves chemical durability and improves impact resistance and mechanical properties, but when Al ₂ O ₃ increases, the refractive index decreases, Tg increases too much, glass May be easily devitrified. Preferably it is 5% or less, More preferably, it is 3% or less.

B ₂ O ₃ is an optional component. B ₂ O ₃ is a component that lowers the Tg, improves the thermal stability of the glass, and improves impact resistance and mechanical properties. However, if the amount of B ₂ O ₃ is large, the refractive index decreases. There is a risk that chemical durability tends to decrease. Preferably it is 20% or less, More preferably, it is 15% or less.

P ₂ O ₅ is an optional component. P ₂ O ₅ is a component that lowers the Tg and is a component for adjusting the Abbe number. However, if the amount of P ₂ O ₅ is large, the refractive index, impact resistance, and mechanical properties are likely to be lowered. Preferably it is 20% or less, More preferably, it is 15% or less, More preferably, it is 10% or less. Most preferably, P ₂ O ₅ is not substantially contained.

SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ + P ₂ O ₅ is 30% or more and less than 65%. When SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ + P ₂ O ₅ is less than 30%, the Abbe number becomes small. Preferably it is 35% or more, more preferably 40% or more. On the other hand, at 65% or more, the refractive index is low. Preferably it is 62% or less, More preferably, it is 60% or less.

MgO is an optional component. MgO is a component that improves the meltability of glass, suppresses devitrification, and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, when the amount of MgO increases, devitrification is promoted. Preferably it is 15% or less, More preferably, it is 10% or less.

CaO is an optional component. CaO is a component that suppresses devitrification and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, when the amount of CaO is large, the chemical strengthening treatment is hindered, and the impact resistance and mechanical properties are likely to deteriorate. Therefore, when CaO is contained, it is preferably 15% or less, more preferably 10% or less.

SrO is an optional component. SrO is a component that suppresses devitrification and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, if the amount of SrO is large, the impact resistance and mechanical properties, which impede the chemical strengthening treatment and increase the specific gravity of the glass, are significantly reduced. Therefore, when SrO is contained, it is preferably 8% or less, more preferably 5% or less, and further preferably 3% or less.

BaO is an optional component. BaO is a component that suppresses devitrification and adjusts optical constants such as the Abbe number and refractive index of glass. On the other hand, when the amount of BaO is large, the impact resistance and mechanical properties that inhibit the chemical strengthening treatment and increase the specific gravity of the glass are remarkably lowered. Therefore, when BaO is contained, it is preferably 8% or less, more preferably 5% or less, and further preferably 3% or less.

TiO ₂ is an optional component, and can be expected to increase the refractive index of the glass and improve the mechanical properties. On the other hand, when TiO ₂ is too much, it is easy to be colored, the transmittance is lowered, and in order to reduce the Abbe number, it is preferably 5% or less, more preferably 3% or less, and further preferably 2% or less.

ZrO ₂ is an optional component, and is a component that increases the refractive index of the glass and increases the chemical durability of the glass. Inclusion of ZrO ₂ can be expected to improve mechanical properties. On the other hand, if there is too much ZrO ₂ , devitrification tends to occur, so it is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. When ZrO ₂ is contained, it is preferably 0.5% or more, more preferably 1% or more, and further preferably 2% or more.

The value obtained by dividing B ₂ O ₃ by Li ₂ O, B ₂ O ₃ / Li ₂ O, is preferably 0.75 or less, more preferably 0.7 or less. If it exceeds 0.75, the volatilization of the glass becomes intense when the glass is melted, and the variation in the refractive index when the reinforced lens is made increases. More preferably, it is 0.6 or less, More preferably, it is 0.5 or less.

Na ₂ O is an optional component that suppresses devitrification, lowers Tg, and enhances the efficiency of replacement with K ⁺ when the strengthened molten salt is a mixed salt of sodium nitrate and potassium nitrate. If it is too high, the refractive index will be low, the Abbe number will be small, and the impact resistance and mechanical properties will tend to deteriorate. Preferably it is 10% or less, More preferably, it is 5% or less. When Na ₂ O is contained, it is preferably 1.5% or more, more preferably 2% or more, and further preferably 2.5% or more.

K ₂ O is an optional component that improves the meltability of the glass and suppresses devitrification. However, if it is too much, the refractive index decreases, the Abbe number decreases, and the impact resistance. And mechanical properties are likely to deteriorate. Preferably it is 5% or less, More preferably, it is 3% or less.

Nb ₂ O ₅ is an optional component that increases the refractive index of glass and can be expected to improve impact resistance and mechanical properties. On the other hand, if Nb ₂ O ₅ is too much, it tends to be devitrified, and the transmittance is lowered. In order to reduce the Abbe number, it is preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less. is there.

Y ₂ O ₃ is an optional component. Y ₂ O ₃ is a component that improves the refractive index of glass and can be expected to improve mechanical properties. However, if the amount of Y ₂ O ₃ is too large, it tends to be devitrified. _Therefore, when they contain Y 2 _{O 3,} preferably 10% or less, more preferably 5% or less.

Gd ₂ O ₃ is an optional component. Gd ₂ O ₃ is a component that does not reduce the Abbe number for improving the refractive index of the glass, so it can be used for adjustment of the optical constant, etc., but it is lost if the amount of Gd ₂ O ₃ is too large. It becomes easy to see through, the specific gravity increases, and the impact resistance and mechanical properties are lowered. Therefore, if containing _Gd 2 _{O 3,} preferably 10% or less, more preferably 5% or less.

Ta ₂ O ₅ is an optional component. Ta ₂ O ₅ is a component that improves the refractive index of the glass. However, if the amount of Ta ₂ O ₅ is too large, it tends to devitrify and the specific gravity also increases. Therefore, if containing _Ta 2 _{O 5,} preferably 10% or less, more preferably 5% or less.

WO ₃ is an optional component. WO ₃ is a component that improves the refractive index of the glass and improves the thermal stability of the glass. However, if the amount of WO ₃ is too large, it tends to devitrify, reduce the Abbe number, and increase the specific gravity. . Therefore, if containing WO _3, preferably 10% or less, more preferably 5% or less.

The glass used for the reinforced lens of the second specification contains Bi ₂ O ₃ , TeO ₂ , Sb ₂ O ₃ , SnO ₂ , and F in addition to the above components in the same manner as the glass used for the reinforced lens of the first specification. May be. The content ratio of these components can be the same as that of the glass used for the reinforced lens of the first specification including the preferred embodiment.

<Glass used for reinforced lenses of the third specification>
Hereinafter, the composition of the glass used for the reinforced lens of the third specification will be described.
SiO ₂ is an essential component in a glass network former, and if it is less than 30%, impact resistance and mechanical properties are lowered. Preferably it is 35% or more, more preferably 40% or more. If it exceeds 65%, Tg tends to be too high. Preferably it is 63% or less, More preferably, it is 62% or less.

Al ₂ O ₃ is an optional component. Al ₂ O ₃ is a component that improves chemical durability and improves impact resistance and mechanical properties, but when Al ₂ O ₃ increases, Tg becomes too high and the glass tends to devitrify. There is a fear. Preferably it is 15% or less, More preferably, it is 13% or less.

B ₂ O ₃ is an optional component. B ₂ O ₃ is a component that lowers the Tg, improves the thermal stability of the glass, and improves impact resistance and mechanical properties. However, if the amount of B ₂ O ₃ is large, chemical durability is increased. It tends to decrease. Preferably it is 40% or less, More preferably, it is 35% or less.

P ₂ O ₅ is an optional component. P ₂ O ₅ is a component that lowers the Tg and is a component that increases the Abbe number. However, if the amount of P ₂ O ₅ is large, impact resistance and mechanical properties are likely to deteriorate. Preferably it is 20% or less, More preferably, it is 15% or less.

SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ + P ₂ O ₅ is 65% or more and less than 80%. When SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ + P ₂ O ₅ is less than 65%, the Abbe number becomes small. Preferably it is 66% or more, More preferably, it is 67% or more. On the other hand, at 80% or more, melting of the glass becomes difficult. Preferably it is 78% or less, More preferably, it is 76% or less.

Li ₂ O is an essential component and is contained at 10% or more. In order to make the chemical strengthening treatment efficient, Li ₂ O is preferably 11% or more, more preferably 12% or more. Further, from the viewpoint of suppressing stress relaxation in the chemically strengthened glass due to devitrification and Tg reduction, Li ₂ O in the glass is preferably 20% or less, more preferably 18% or less.

Na ₂ O is an optional component that suppresses devitrification, lowers Tg, and enhances the efficiency of replacement with K ⁺ when the strengthened molten salt is a mixed salt of sodium nitrate and potassium nitrate. If it is too high, the Abbe number becomes small, and the impact resistance and mechanical properties are likely to deteriorate. Preferably it is 10% or less, More preferably, it is 5% or less. When Na ₂ O is contained, it is preferably 1.5% or more, more preferably 2% or more, and further preferably 2.5% or more.

K ₂ O is an optional component that improves the meltability of the glass and suppresses devitrification. However, if it is too large, the Abbe number decreases, impact resistance and mechanical properties decrease. Easy to do. Preferably it is 5% or less, More preferably, it is 3% or less.

The total content of alkali metal components (R ₂ O = Li ₂ O + Na ₂ O + K ₂ O) is 10 to 25%. If it exceeds 25%, the Abbe number will be small, and the acid resistance and water resistance may be reduced. Preferably it is 20% or less, More preferably, it is 18% or less, More preferably, it is 15% or less. Further, Li ₂ O content relative to _{_{_{R 2 O Li 2 O / (}}} Li 2 O + Na 2 O + K 2 O) is 0.5 or more. By setting Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) to 0.5 or more, the efficiency with which Li ⁺ is exchanged with Na ⁺ or K ⁺ can be increased. 0.6 or more is more preferable, and 0.7 or more is more preferable.

Nb ₂ O ₅ is an optional component that increases the refractive index of glass and can be expected to improve impact resistance and mechanical properties. On the other hand, if Nb ₂ O ₅ is too much, it tends to be devitrified, and the transmittance is lowered. In order to reduce the Abbe number, it is preferably 10% or less, more preferably 8% or less, and further preferably 5% or less. is there.

La ₂ O ₃ is an optional component. La ₂ O ₃ is a component that does not reduce the Abbe number for improving the refractive index of the glass, so it can be used for adjusting the optical constant, etc., but it is lost if the amount of La ₂ O ₃ is too large. It becomes easy to see through, the specific gravity increases, and the impact resistance and mechanical properties are lowered. Therefore, if containing _La 2 _{O 3,} preferably 10% or less, more preferably 8% or, more preferably not more than 5%.

Y ₂ O ₃ is an optional component. Y ₂ O ₃ is a component that improves the refractive index of glass and can be expected to improve mechanical properties. However, if the amount of Y ₂ O ₃ is too large, it tends to be devitrified. _Therefore, when they contain Y 2 _{O 3,} preferably 5% or less, more preferably 3% or less.

Gd ₂ O ₃ is an optional component. Gd ₂ O ₃ is a component that does not reduce the Abbe number for improving the refractive index of the glass, so it can be used for adjustment of the optical constant, etc., but it is lost if the amount of Gd ₂ O ₃ is too large. It becomes easy to see through, the specific gravity increases, and the impact resistance and mechanical properties are lowered. Therefore, if containing _Gd 2 _{O 3,} preferably 5% or less, more preferably 3% or less.

Ln ₂ O ₃ (Ln is at least one selected from the group consisting of Y, La, Gd, Yb, and Lu. That is, Ln ₂ O ₃ is La ₂ O ₃ + Y ₂ O ₃ + Gd ₂ O ₃ Is an optional component. Ln ₂ O ₃ is a component that improves the refractive index of the glass. However, if the amount of Ln ₂ O ₃ is too large, it tends to devitrify. Therefore, if containing _Ln 2 _{O 3,} preferably 10% or less, more preferably 5% or less.

Ta ₂ O ₅ is an optional component. Ta ₂ O ₅ is a component that improves the refractive index of the glass. However, if the amount of Ta ₂ O ₅ is too large, it tends to devitrify and the specific gravity also increases. Therefore, if containing _Ta 2 _{O 5,} preferably 5% or less, more preferably 3% or less.

WO ₃ is an optional component. WO ₃ is a component that improves the refractive index of the glass and improves the thermal stability of the glass. However, if the amount of WO ₃ is too large, it tends to devitrify, reduce the Abbe number, and increase the specific gravity. . Therefore, if containing WO _3, preferably 5% or less, more preferably 3% or less.

_{_{_{TiO 2 + Nb 2 O 5 +}}} WO 3 is 10% or less. If it exceeds 10%, the Abbe number becomes small. More preferably, it is 8% or less, More preferably, it is 5% or less.

The glass used for the strengthened lens of the third specification contains Bi ₂ O ₃ , TeO ₂ , Sb ₂ O ₃ , SnO ₂ , and F in addition to the above components in the same manner as the glass used for the strengthened lens of the first specification. May be. The content ratio of these components can be the same as that of the glass used for the reinforced lens of the first specification including the preferred embodiment.

[Method of manufacturing reinforced lens]
The reinforced lens of this invention can be manufactured by the method including the following process A and process B, for example.
(Step A) 30 to 65 mol% of SiO ₂ , 10 mol% or more of Li ₂ O, 0 to 10 mol% of SrO + BaO, and Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) is 0.5 or more Mold glass into a lens molding.

(Step B) The lens molding is subjected to chemical strengthening treatment.
Thereby, a reinforced lens excellent in impact resistance and mechanical properties is produced. The chemical strengthening treatment can be performed by a conventionally known method. Specifically, the lens molding is brought into contact with a melt of an alkali metal salt containing an alkali metal ion having an ionic radius larger than that of the alkali metal ion in the lens molding by immersion or the like. As a result, the reinforced lens of the present invention in which the metal ions having a small ion radius are replaced with the metal ions having a large ion radius only in the surface layer portion of the lens molding, and the surface layer portion is given compressive stress.

Here, in the manufacturing method of the present invention, the chemical strengthening treatment of the lens molded body in the step B is a strengthened molten salt containing at least sodium nitrate, and the strengthened molten salt contains 25% or more of sodium nitrate in terms of mass%. And a strengthened molten salt containing 95% or more of sodium nitrate and potassium nitrate (hereinafter referred to as “strengthened molten salt (X)”), the chemical strengthening treatment temperature is T (unit: ° C.), and the treatment time is t. When (unit: time), it is performed under conditions that satisfy the following formula (1). Hereinafter, the chemical strengthening treatment process according to the production method of the present invention is referred to as process B2.
30000 <T ^1.8 × t ^0.5 <50000 Formula (1)

By performing the chemical strengthening treatment in the above-described conditions in the step B2, the lens molded body obtained in the above step A can be made into a strengthened lens with almost no change in shape. Specifically, the amount of change in the radius of curvature of the first main surface before and after the chemical strengthening treatment in the lens molded body having a predetermined shape can be set to 10 μm or less by the above method. The amount of change is preferably 5 μm or less, more preferably 3 μm or less, and particularly preferably 1 μm or less. Hereinafter, each process of the manufacturing method of this invention is demonstrated.

<Process A (Lens molding process)>
In order to produce a lens molded body, first, raw materials are weighed so as to have the predetermined glass composition and mixed uniformly. The prepared mixture is put into a platinum crucible, a quartz crucible or an alumina crucible and roughly melted. Thereafter, it is placed in a gold crucible, platinum crucible, platinum alloy crucible or iridium crucible and melted at a temperature range of 1200 to 1400 ° C. for 2 to 10 hours, clarified and homogenized by degassing, stirring, etc. By casting and gradually cooling, a glass ingot or further molding is performed to produce a lens preform.

For the lens preform produced above, a lens molded body can be produced using means such as reheat press molding or precision press molding. That is, after the glass raw material is melted, a lens molded body is produced by a direct press method, or a preform for mold press molding is produced, and after the reheat press molding is performed on the preform, polishing is performed. To produce a lens molded body, for example, by performing precision press molding on a preform produced by polishing, to produce a lens molded body, or by directly polishing from the optical glass ingot to form a lens The body can be made. The means for producing the lens molded body is not limited to these means.

<Process B2 (Lens Molded Body Chemical Strengthening Process)>
The chemical strengthening treatment in the present invention is characterized in that sufficient impact resistance and mechanical properties can be obtained under chemical strengthening conditions in which the lens shape of the lens molded body obtained by molding does not change greatly, and the exchange of main alkali metal ions Is the replacement of Li ⁺ ions with Na ⁺ ions. In step B2, chemical strengthening treatment is performed using the strengthened molten salt (X) under conditions of a chemical strengthening treatment temperature T (unit: ° C.) and a treatment time t (unit: time) that satisfy the above formula (1). .

(Strengthened molten salt (X))
As the melt of the alkali metal salt used for the chemical strengthening treatment, the strengthened molten salt (X) is used. Unless otherwise specified, the content of each component is expressed as a percentage by mass with respect to the total amount of the strengthened molten salt (X).

(1) Sodium nitrate Sodium nitrate is essential in the strengthened molten salt (X). The content of sodium nitrate in the strengthened molten salt (X) is 25% or more. The content of sodium nitrate is preferably 30% or more, more preferably 50% or more. The upper limit of the content of sodium nitrate is 100%, preferably 95% or less, more preferably 90% or less.

(2) Potassium nitrate Potassium nitrate is mainly strengthened because the rate at which K ⁺ in the molten molten salt (X) is ion exchanged with Li or Na in the glass is slower than the ion exchange between Li ⁺ ions and Na ⁺ ions. It is not an ion but an optional component. Potassium nitrate, the freezing point depression, lowering the melting point of the reinforcing molten salt (X), and as the lithium nitrate, is not that difficult and enhanced too much content, further Li ⁺ ions and Na ⁺ ions Since ion exchange, ion exchange of Na ⁺ ions and K ⁺ ions and mutual diffusion are promoted and strengthening can be promoted more than sodium nitrate single molten salt, they may be mixed.

The content of potassium nitrate in the reinforced molten salt (X) is preferably 10% or more, and more preferably 20% or more. The content of potassium nitrate is 75% or less in relation to the content of sodium nitrate. If the content exceeds 75%, the ion exchange rate may be slow. The content of potassium nitrate is preferably 70% or less, more preferably 50% or less.

The total amount of sodium nitrate and potassium nitrate is 95% or more. The total amount is preferably 98% or more, more preferably 99% or more.
(3) Lithium nitrate In the strengthened molten salt (X), lithium nitrate is an optional component. If the content of lithium nitrate exceeds 5%, Na ⁺ ions and K ⁺ ions in the molded lens body are promoted to exchange with Li ⁺ ions and are not easily strengthened. Moreover, the surface layer part of the reinforced lens obtained becomes a tension layer instead of a compression layer, and the strength may be smaller than that of the lens molding. Therefore, the content of lithium nitrate is preferably 3% or less, more preferably 2% or less, and still more preferably 1% or less.

The strengthened molten salt (X) used for the chemical strengthening treatment of the lens molded body consists essentially of the above components, but may contain other components as required while maintaining the above essential composition range. Examples of other components include sodium sulfate, potassium sulfate, sodium chloride, potassium chloride, calcium sulfate, strontium sulfate, barium sulfate, calcium sulfate, strontium chloride, and barium chloride, and other alkali sulfates, alkali chlorides, and alkaline earths. Examples thereof include sulfates and alkaline earth chlorides.

The content of these other components in the strengthened molten salt (X) is 5% or less, preferably 1% or less. If it is in the said range, another component has an effect which prevents volatilization in melt | dissolution of strengthening molten salt (X). On the other hand, if it exceeds 5%, it is difficult to perform strengthening when chemical strengthening treatment is performed.

(Chemical strengthening treatment temperature and treatment time)
In the chemical strengthening treatment in the present invention, the heating temperature of the strengthened molten salt (X), that is, the chemical strengthening treatment temperature is T (unit: ° C.), and the immersion time of the lens molded body in the strengthened molten salt (X), that is, the processing time is When t (unit: time) is used, T and t are processes satisfying the above formula (1), that is, 30000 <T ^1.8 × t ^0.5 <50000.

Using the manufacturing method of the present invention, the lens molded body obtained by using the predetermined glass in the step A is subjected to a chemical strengthening treatment using a strengthened molten salt (X) under the conditions where T and t satisfy the above formula (1). The reinforced lens obtained in this way is a reinforced lens that has sufficient impact resistance and has little shape change due to chemical strengthening treatment. That is, the lens is a reinforced lens that can be evaluated by the above method and has a falling ball strength of 80 cm or more and a change amount of the radius of curvature of the first main surface of 10 μm or less.

In the reinforced lens obtained when T ^1.8 × t ^0.5 is 30000 or less, sufficient impact resistance and mechanical properties cannot be obtained. Further, if T ^1.8 × t ^0.5 is 50000 or more, the lens shape, particularly the radius of curvature of the first main surface, greatly changes.

The chemical strengthening treatment temperature T is preferably less than (Tg-100) ° C. of the glass constituting the lens molding. If the chemical strengthening treatment temperature T is (Tg-100) ° C. or more, there is a possibility that the strengthened lens of the present invention cannot be obtained without sufficient strengthening of the molded lens body even if ion exchange occurs due to stress relaxation. is there.

The treatment time t is preferably 0.25 hours or more. If it is less than 0.25 hours, when the immersion time is too short and a large number of lens molded bodies are arranged side by side and subjected to chemical strengthening treatment, unevenness may be caused in some places.

In addition, the chemical strengthening treatment step of the lens molded body in the step B2 may include the following (1) preheating step before the immersion treatment of the lens molded body in the reinforced molten salt (X). You may have the following (2) cooling and washing | cleaning processes after a process.

That is, in the process B2, for example, a sample holder dedicated to the lens molded body is prepared, and the sample holder in which a large number of the lens molded bodies obtained in the process A are arranged is continuously used in the preheating furnace and the reinforced molten salt (X). It may be a step in which a preheating step, a chemical strengthening treatment step, a cooling step, and a washing step are successively performed by passing through the filled strengthening tank, cooling tank, and washing tank.

(1) Preheating step Before the lens molded body is further immersed in the reinforced molten salt (X), the lens molded body is preheated so that the temperature of the lens molded body is equal to or higher than the melting point of the reinforced molten salt (X). It is preferable to keep it. This prevents solidification of the molten salt on the surface of the lens molded body when immersed in the reinforced molten salt (X), reduces the ion exchange rate, and uneven distribution in the glass surface of the surface layer portion to which compressive stress is applied. It is for suppressing becoming.

The preheating temperature of the lens molding is preferably less than 400 ° C, more preferably 350 ° C or less. If it is 400 ° C. or higher, the shape may change due to the influence of residual stress during preheating or due to nonuniformity of the glass in-plane temperature at the point of contact with the sample holder.

(2) Cooling and washing step The reinforced lens of the present invention in which the lens molded body is immersed in the reinforced molten salt (X) under the above-described predetermined conditions to form a reinforced layer having a compressive stress applied to the lens molded body. can get. The reinforced lens is usually pulled up from the reinforced molten salt (X) and gradually cooled.

In the above, instead of gradual cooling, the reinforced lens pulled up from the reinforced molten salt (X) is kept waiting for 30 seconds to 2 minutes, and after the tempered lens temperature becomes 300 ° C. or lower, the reinforced lens is brought into contact with the refrigerant. It is preferable to cool rapidly. The cooling rate of the reinforced lens is preferably 100 ° C./min or more. Moreover, 4000 degrees C / min or less is preferable and 3000 degrees C / min or less is more preferable.

When the cooling rate of the reinforced lens is less than 100 ° C./min, the reinforced molten salt (X) adhering to the reinforced lens also undergoes ion exchange only at the contact point in the cooling process, and the reinforced lens is given compressive stress. Since the in-plane distribution of the layers becomes non-uniform, the shape of the obtained reinforced lens, particularly the radius of curvature of the first main surface, may change significantly.

Also, if the cooling rate of the reinforced lens exceeds 4000 ° C./min, the shape of the reinforced lens, particularly the curvature radius on the first main surface, may change significantly. In addition, if the lens is brought into contact with a coolant without waiting to be cooled rapidly, the reinforced lens may be broken by a heat shock. Further, the shape of the reinforced lens, particularly the radius of curvature of the first main surface, may change greatly.

In order to drop the strengthened molten salt (X) adhering to the strengthening lens after cooling or during the cooling process, ultrasonic cleaning is preferable. The cleaning liquid is not particularly limited, but a cleaning liquid that has high solubility of the strengthened molten salt (X) and is suitable for cleaning the strengthened lens is selected. For example, in the case of washing in a continuous washing line of a plurality of tanks, after the ion exchange water and IPA (isopropyl alcohol) washing, a drying process is performed.

Thus, in the manufacturing method of the present invention, a reinforced lens having sufficient impact resistance and little shape change due to chemical strengthening treatment can be obtained. In the manufacturing method of the present invention, it is preferable that the first main surface and the second main surface of the reinforced lens are not re-polished after the chemical strengthening treatment step of the B2 step. This is because, according to the manufacturing method of the present invention, the shape of the reinforced lens is sufficiently stable even if the reinforced lens is not re-polished after the chemical strengthening treatment step of the B2 step. On the other hand, the reinforcing lens side surface may be subjected to centering processing or the like as necessary.

The reinforced lens of the present invention may include an antireflection layer and / or an antifouling coating layer on at least one main surface of the first main surface and the second main surface. The antireflection layer is provided in order to improve the transmittance by preventing reflection of light incident on the reinforced lens and to efficiently use incident light. In addition, the antifouling coating layer can be expected to have functions such as improvement of surface hardness, scratch resistance, and wear resistance, as well as suppression of deterioration in image quality of the camera due to adhesion of dirt such as sebum oil, raindrops, and dust.

In the reinforced lens produced as described above, when the reinforced lens is a lens arranged closest to the subject side of the imaging lens and the first main surface is a main surface arranged on the subject side, at least the first main surface Preferably, an antireflection layer and an antifouling coating layer are formed. When both the antireflection layer and the antifouling coating layer are provided, the antireflection layer and the antifouling coating layer are usually provided in this order from the reinforced lens side. The same applies to the second main surface. The types and forming methods of the constituent materials for the antireflection layer and antifouling coating layer are shown below. The antireflection layer and the antifouling coating layer are formed by coating the first main surface and / or the second main surface of the reinforced lens obtained after the step B2.

(C1) Formation of antireflection layer Antireflection layer is formed by silica, titania, niobium oxide, tantalum pentoxide, yttria, nitridation formed by sputtering method, vacuum deposition method, ion beam method, ion plating method, plasma CVD method, etc. One or more layers of silicon, silicon oxynitride, aluminum oxynitride, sialon, magnesium fluoride, zirconia, alumina, etc., silicate-based, silicone-based, fluorinated methacrylate-based films formed by sol-gel method, coating method, etc. It is composed of a film or the like. The thickness of the antireflection layer is usually in the range of 100 to 600 nm. The antireflection layer may be provided on the first main surface and the second main surface of the reinforced lens. The antireflection layer preferably has a reflectance of 1% or less over, for example, 420 to 750 nm.

(C2) Formation of antifouling coating layer Antifouling coating layer is formed by sputtering, vacuum deposition, ion beam method, ion plating method, plasma CVD method or the like, titania, tin oxide, tungsten oxide, strontium titanate, etc. And a silicate-based, silicone-based, fluorinated methacrylate-based, or fluorine-containing organic compound film containing the photocatalytic metal fine particles formed by a sol-gel method, a coating method, or the like. The thickness of the antifouling coating layer is in the range of 100 to 2000 nm. The antifouling coating layer is not particularly required to be provided on the second main surface, but may be formed on the second main surface when formed by dip coating or the like among the application methods.

The reinforced lens produced in this way is useful for various camera applications, and in particular, it is suitably used for applications exposed to harsh environments such as an imaging lens used for a vehicle-mounted camera.

The reinforced lens of the present invention described above is a reinforced lens having high impact resistance, and is suitable for an imaging lens used for a vehicle-mounted camera exposed to a harsh environment. Further, according to the production method of the present invention, the lens is a reinforced lens having excellent impact resistance and mechanical properties, and also having good acid resistance and water resistance, and the shape does not change greatly even after chemical strengthening treatment. A lens can be obtained.

The raw materials were weighed so as to have chemical compositions shown in Tables 1 to 6 (mol% in terms of oxide). As raw materials, high-purity raw materials used for ordinary lenses such as oxides, hydroxides, carbonates, nitrates, fluorides, hydroxides, and metaphosphate compounds are selected as raw materials for each component. Used.

The weighed raw materials are uniformly mixed, put in a platinum crucible with an internal volume of about 300 mL, melted at about 1400 ° C. for about 2 hours, stirred and kept at 1400 ° C. for 0.5 hour for clarification, and the temperature reaches about 650 ° C. After casting into a preheated rectangular mold having a length of 50 mm and a width of 100 mm, the glass was slowly cooled at about 0.5 ° C./min to obtain a glass of length 50 mm × width 100 mm × thickness 15 mm.

The glass obtained above is processed into a plate shape having a size of about 20 mm × 20 mm × 2 mm (thickness), and the surface of 20 mm × 20 mm is mirror-polished with CeO ₂ to be a glass plate for CIL evaluation test A shaped molded body was obtained. Next, the following chemical strengthening treatment was performed. That is, nitrate of NaNO ₃ to KNO ₃ is 100: 0 nitrate (hereinafter referred to as “100Na”), 75:25 nitrate (hereinafter referred to as “75Na25K”), 50:50 nitrate (hereinafter referred to as “100Na”). , “50Na50K”) and 0: 100 nitrate (hereinafter, “100K”) are prepared, heated to 400 ° C., and melted into melts of glass for 30 minutes each. Immersion and chemical strengthening treatment were performed to obtain an evaluation sample for CIL evaluation test. In addition, for 0: 100 nitrate, an evaluation sample for CIL evaluation test obtained by immersion for 4 hours was also prepared. The size of the obtained sample for evaluation was 20 mm × 20 mm × 2 mm (thickness).

^{^{Incidentally, 400 ℃, T 1.8 × t}} 0.5 chemical strengthening treatment of 30 minutes is ^{34134, 400 ℃, T 1.8 ×} t 0.5 chemical strengthening treatment of 4 hours is a 96547 .

[Evaluation]
The glass transition point (Tg), refractive index (nd), Abbe number (νd), specific gravity (d), Young's modulus (E), devitrification temperature, water resistance (RW), acid resistance of the above glass are as follows. Sex (RA) was measured. Among these physical properties, the refractive index (nd), Abbe number (νd), specific gravity (d), water resistance (RW), acid resistance (RA) are as described above when the reinforced lens after chemical strengthening is used. It is substantially the same as refractive index (nd), Abbe number (νd), specific gravity (d), water resistance (RW), and acid resistance (RA).

In addition, as described above, the crack initiation load (CIL) was measured as follows for the evaluation sample in which glass was molded into a plate shape and chemically strengthened. In the present invention, the CIL of the reinforced lens refers to the CIL of the glass plate measured in this way.

Tg: A glass sample processed into a cylindrical shape having a diameter of 5 mm and a length of 20 mm, and a temperature rising rate of 5 ° C./min by a thermal expansion method using a thermomechanical analyzer (trade name: TMA4000SA, manufactured by Bruker AXS) Measured with

Nd: Glass was processed into a triangular prism having a side of 30 mm and a thickness of 10 mm, and measured with a refractometer (manufactured by Kalnew, instrument name: KPR-2000).

Δnd: nd of a glass prism melted at 1200 to 1400 ° C. for 2 hours to obtain the triangular prism and a glass prism melted at the same temperature for 6 hours to obtain the triangular prism were measured by the above method, and the refraction Rate differences were evaluated.

Νd: nC and nF were measured in the same manner as nd, and calculated from νd = (nd−1) / (nF−nC).

Specific gravity: The ratio between the mass of the glass sample and the mass of 4 ° C. pure water of the same volume under a pressure of 101.325 kPa (standard atmospheric pressure) is displayed as SG, and JIS Z8807 (1976, in liquid) It measured according to the measuring method to weigh.

E: About the sample of the block-shaped glass of 20 mm x 20 mm x 10 mm, it measured using the ultrasonic precision board thickness meter (The product made by OLYMPUS, MODEL 38DL PLUS) (unit: GPa).

RW: Measured according to the measuring method (powder method) of chemical durability of JOGIS06-2008 optical glass. Specifically, when the glass was made into a glass powder having a diameter of 420 to 600 μm using an alumina mortar and pestle, the mass reduction ratio (%) when immersed in 80 mL of pure water at 100 ° C. for 1 hour was measured. If the mass reduction ratio is less than 0.05 (%), it is grade 1, if it is 0.05 or more and less than 0.10 (%), it is grade 2, and if it is 0.10 or more and less than 0.25 (%), it is grade 3, 0.25 or more and 0. Less than .60 (%) was grade 4, 0.60 or more and less than 1.10 (%), grade 5 and 1.10 (%) or more, grade 6.

RA: Measured according to the measuring method (powder method) of chemical durability of JOGIS06-2008 optical glass. Specifically, when the glass was made into a glass powder having a diameter of 420 to 600 μm using an alumina mortar and pestle, the mass reduction ratio (%) when immersed in 80 mL of a 0.01 N nitric acid aqueous solution at 100 ° C. for 1 hour. ) Was measured. Grade 1 if the mass reduction rate is less than 0.20 (%), Grade 2 if it is less than 0.20 and less than 0.35 (%), Grade 3, if it is less than 0.35 and less than 0.65 (%), 0.65 or more and 1 Less than .20 (%), grade 4, 1.20 or more and less than 2.20 (%), grade 5, and 2.20 (%) or more, grade 6.

CIL: measured by the method described above. When the CIL value was 2000 gf or more, it was expressed as “> 2000”. In Tables 1 to 6, the CIL of the glass plate after chemical strengthening treatment at 400 ° C. and 100Na for 30 minutes was expressed as CIL _100Na-05h . The conditions were similarly indicated for the CIL of the glass plate chemically treated under other conditions.

The results are shown in Tables 1 to 6 together with the glass composition. In Tables 1-6, Examples 1-31, 41-46 are Examples, Examples 32-35, 37-40 are Comparative Examples, and Example 36 is a Reference Example. “-” In the table means unmeasured.

Moreover, in the glass of Table 7, the glass of Example 1, 7, 16, 18, 23, 25, 42, 44 corresponding to the said Example, and the glass of Example 35, 36, 38 corresponding to a comparative example The raw materials are weighed so as to have the chemical compositions shown in Tables 1 to 6, mixed in the same manner as described above, placed in a platinum crucible having an internal volume of about 700 mL, melted at 1200 to 1400 ° C. for about 6 hours, and stirred. After fining, hold at 1200-1400 ° C for 0.5 hour, cast into a rectangular mold of 100mm length × 150mm width preheated to approximately 650 ° C, and then slowly cool at about 0.2 ° C / min to 100mm length A glass having a width of 150 mm and a thickness of 40 mm is obtained, and after slicing and polishing, a diameter D1 having a cross-sectional shape as shown in FIG. 1 is 14 mm, a radius of curvature R1 in the first main surface 1 is 12 mm, and a second main surface 2 Curved surface The diameter D2 is 5.72 mm, the curvature radius R2 is 3 mm, the thickness T1 of the convex portion is 1.4 mm, the distance T2 between the apex of the curved surface of the second main surface 2 and the base is 2.1 mm, and the reinforced lens 10 A lens molded body having a thickness of 3.5 mm was processed. The shape of the lens molding was measured with a 3D measuring device (manufactured by KEYENCE, VR-3200).

The obtained lens molding was subjected to chemical strengthening treatment under various conditions shown in Table 7 to obtain a strengthened lens. The chemical strengthening treatment includes nitrate with a mass% of NaNO ₃ to KNO ₃ of 75:25 (indicated as “75% NaNO ₃ + 25% KNO ₃ ” in Table 7), and nitrate of 0: 100 (in Table 7, “ 100% KNO ₃ ”) was prepared, and strengthening was performed at the chemical strengthening treatment temperature T (unit: ° C.) and the treatment time t (unit: time) shown in Table 7. Table 7 also shows T ^1.8 × t ^0.5 .

Prior to strengthening, put in an electric furnace kept at 400 ° C for 10 minutes, preheat and then strengthen with reinforced molten salt under the specified strengthening conditions. It was ultrasonically cleaned for 10 minutes and dried to obtain a reinforced lens. After measuring the shape of the reinforced lens with the same 3D measuring instrument as described above, the falling ball strength was evaluated. The results are shown in Table 7.

Using the glass of Example 7, Example 16, and Example 25, a lens molded body was obtained in the same manner as described above, and the obtained lens molded body was obtained by adding 400% at 30 ° C. with nitrate of NaNO ₃ to KNO ₃ of 75: 25% by mass. Reinforced lenses were obtained. For the reinforced lens obtained, after ultrasonic cleaning, a total of 7 layers of SiO ₂ and Si ₃ N ₄ are alternately laminated on the first main surface by a sputtering process to form an antireflection layer with a total thickness of 0.5 μm. A reinforced lens with an antireflection layer was obtained. In any reinforced lens with an antireflection layer, the reflectance was 1% or less over 420 to 750 nm. The falling ball strength was also evaluated for the three types of reinforced lenses with an antireflection layer. The results are shown in Table 7 in Example 7-C, Example 16-C, and Example 25-C.

Falling ball strength [cm]: measured by the method described above.
Change in shape before and after chemical strengthening: The amount of change [μm] in the radius of curvature of the first principal surface of the molded lens and the strengthened lens was calculated by the method described above.

The glass in each Example are both the Li ₂ O and containing at least 10 mol%, and _{_{_{Li 2 O / (Li 2 O}}} + Na 2 O + K 2 O) ≧ 0.5, SrO + BaO is less 10 mol%, SiO ₂ 30 Since it is ˜65 mol%, CIL has a high strength of 100 gf or more. CIL is any one of CIL _100Na-0.5h , CIL _75Na25K-0.5h , CIL _50Na50K-0.5h , that is, any of CIL of a glass plate chemically strengthened using reinforced molten salt (X). May be 100 gf or more.

In addition, it is assumed that Example 34 glass in which B ₂ O ₃ / Li ₂ O greatly exceeds 0.75 has a high Δnd of 0.003 or more and a process margin at the time of manufacture is narrow.

In addition, the strengthened lens using the glass of this example of Examples 1, 7, 16, 18, 23, 25, 42, 44 is nitrate (strengthened molten salt (X)) in which the mass% of NaNO ₃ to KNO ₃ is 75:25. ), The falling ball strength is 80 cm or more even under the chemical strengthening condition at 400 ° C. for 30 minutes, and the shape change is suppressed to 10 μm or less. On the other hand, when the tempering time is extended or the tempering temperature is increased to 500 ° C. with the reinforced lens using the glass of Examples 7 and 16, the shape change becomes large. This is because T ^1.8 × t ^0.5 is out of the range of the production method of the present invention.

Further, in the case of a reinforced lens using the glass of Example 7 using a reinforced molten salt of 100% KNO ₃ which is not a reinforced molten salt (X), the falling ball strength is 80 cm or less in the chemical tempering treatment at 400 ° C. for 30 minutes. The shape change is 10 μm or more, and it can be seen that the shape change is large despite the slow K ion strengthening speed. On the other hand, in the reinforced lens using the glass of Example 7, when the tempering time is extended to 4 hours at 100% KNO ₃ and 400 ° C., the falling ball strength reaches 80 cm or more, but the shape change is further increased.

In this way, from the results of Table 7, if the glasses of Examples 1, 7, 16, 18, 23, 25, 42, and 44 of this example are used, the processing time is such that the shape does not change greatly even when chemically strengthened. It can be seen that a reinforced lens having sufficiently high impact resistance and a high refractive index can be obtained.

In Comparative Examples 32 to 34, since SiO ₂ is less than 30 mol%, CIL is estimated to be less than 100 gf and falling ball strength is estimated to be less than 80 cm.
Further, the glasses of Example 35 (Comparative Example) and Example 36 (Reference Example) have Li ₂ O of less than 10 mol% and poor chemical strengthening efficiency. In Example 35, CIL is less than 100 gf. In Example 36, CIL _100K-4h is ₁₀₀ gf or more, but any of CIL _100Na-0.5h , CIL _75Na25K-0.5h , and CIL _50Na50K-0.5h does not satisfy the condition of 100 gf or more. In the case of the strengthened lens using the glass of Example 36, the falling ball strength is 75% NaNO ₃ + 25% KNO ₃ strengthened molten salt or 100% KNO ₃ strengthened molten salt at 400 ° C. for a strengthening time of 30 minutes. Like the reinforced lens using the glass of Example 7 having a falling ball strength of less than 80 cm, the falling ball strength is more than 80 cm at 100% KNO ₃ at 400 ° C. for 4 hours strengthening time, but the shape change due to strengthening is 10 μm. Become super.

The glass of Example 37 has Li ₂ O / (Li ₂ O + Na ₂ O + K ₂ O) of less than 0.5, the efficiency of chemical strengthening is poor, and the CIL is less than 100 gf, so the falling ball strength is less than 80 cm. It is guessed. In Examples 38 to 40, SrO + BaO is more than 10 mol%, the chemical strengthening efficiency is poor, and the CIL is less than 100 gf. Therefore, it is estimated that the falling ball strength is less than 80 cm. When the glass of Example 38 was made into a reinforced lens, it was a 75% NaNO ₃ + 25% KNO ₃ reinforced molten salt, and even when tempered at 400 ° C. for 30 minutes, the falling ball strength was as low as 10 cm.

Therefore, the reinforced lens of the present invention is excellent in impact resistance, and has a strength that can sufficiently withstand harsh usage environments without deterioration in image quality when used for an imaging lens of an in-vehicle camera, for example. It is. Therefore, it is suitable for an imaging lens used for a vehicle-mounted camera that is exposed to a harsh environment. In addition to in-vehicle cameras, it is also suitable for applications such as robot vision sensors, surveillance cameras, and wearable cameras.

Further, according to the method for manufacturing a reinforced lens of the present invention, a reinforced lens having high impact resistance and suppressed shape change due to chemical strengthening treatment can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Reinforcement lens, 1 ... 1st main surface, 2 ... 2nd main surface, 11 ... Horizontal surface, 12 ... Iron ball.

Claims

A chemically strengthened lens of a glass lens molded body, wherein the glass contains 30 to 65 mol% of SiO 2 , 10 mol% or more of Li 2 O, 0 to 10 mol% of SrO + BaO, and Li 2 O / (Li 2 A reinforced lens in which O + Na 2 O + K 2 O) is 0.5 or more.
2. The falling ball strength indicated as a height at which the strengthening lens does not break when a 64.6 g iron ball is dropped toward the center of the strengthening lens placed on a horizontal plane is 80 cm or more. Reinforced lens.
The lens molding has a first main surface and a second main surface facing each other. The lens molding has a diameter of 14 mm, a radius of curvature of the first main surface of 12 mm, and the second main surface. 3. The reinforced lens according to claim 1, wherein the amount of change in the radius of curvature of the first main surface before and after chemical strengthening when molded to a radius of curvature of 3 mm is 10 μm or less.
The reinforced lens according to any one of claims 1 to 3, wherein the reinforced lens has a crack initiation load (CIL) of 100 gf or more.
The reinforced lens according to any one of claims 1 to 4, wherein the glass has a glass transition point (Tg) of 500 ° C to 630 ° C.
6. The reinforced lens according to claim 1, wherein the reinforced lens has a refractive index (nd) of 1.73 to 2.10 and an Abbe number (νd) of 15 to 45.
The reinforced lens according to any one of claims 1 to 5, wherein the reinforced lens has a refractive index (nd) of 1.63 or more and less than 1.73 and an Abbe number (νd) of 35 to 55.
6. The reinforced lens according to claim 1, wherein the reinforced lens has a refractive index (nd) of 1.50 or more and less than 1.63 and an Abbe number (νd) of 45 to 65.
The glass is expressed in mol% based on oxide,
SiO 2 : 30% to 65%,
Al 2 O 3 : 0% to 20%,
B 2 O 3 : 0% to 40%,
P 2 O 5 : 0% to 20%,
MgO: 0% to 20%,
CaO: 0% to 20%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO 2 : 0% to 20%,
ZrO 2 : 0% to 15%,
Li 2 O + Na 2 O + K 2 O: 10% to 30%,
Li 2 O: 10% to 30%,
Na 2 O: 0% to 15%,
K 2 O: 0% to 5%,
Nb 2 O 5 : 0% to 30%,
Ln 2 O 3 : 0% to 20%,
La 2 O 3 : 0% to 20%,
Y 2 O 3 : 0% to 20%,
Gd 2 O 3 : 0% to 20%,
Ta 2 O 5 : 0% to 20%,
WO 3: 0% ~ 20%
The reinforced lens according to any one of claims 6 to 8, comprising:
The glass is expressed in mol% based on oxide,
SiO 2 : 30% to 55%,
Al 2 O 3 : 0% to 5%,
B 2 O 3 : 0% to 40%,
P 2 O 5 : 0% to 20%,
MgO: 0% to 10%,
CaO: 0% to 10%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO 2 : 0% to 20%,
ZrO 2 : 0% to 15%,
Li 2 O + Na 2 O + K 2 O: 10% to 30%,
Li 2 O: 10% to 30%,
Na 2 O: 0% to 15%,
K 2 O: 0% to 5%,
Nb 2 O 5 : 0% to 30%,
Ln 2 O 3 : 0% to 20%,
La 2 O 3 : 0% to 20%,
Y 2 O 3 : 0% to 20%,
Gd 2 O 3 : 0% to 20%,
Ta 2 O 5 : 0% to 20%,
WO 3: 0% ~ 20%
The reinforced lens according to claim 6, comprising:
The glass is expressed in mol% based on oxide,
SiO 2 : 30% to 60%,
Al 2 O 3 : 0% to 10%,
B 2 O 3 : 0% to 20%,
P 2 O 5 : 0% to 20%,
MgO: 0% to 20%,
CaO: 0% to 20%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO 2 : 0% to 5%,
ZrO 2 : 0% to 15%,
Li 2 O + Na 2 O + K 2 O: 10% to 30%,
Li 2 O: 10% to 30%,
Na 2 O: 0% to 10%,
K 2 O: 0% to 5%,
Nb 2 O 5 : 0% to 15%,
Ln 2 O 3 : 0% to 20%,
La 2 O 3 : 0% to 20%,
Y 2 O 3 : 0% to 10%
Gd 2 O 3 : 0% to 10%,
Ta 2 O 5 : 0% to 10%,
WO 3 : 0% to 10%
The reinforced lens according to claim 7, comprising: SiO 2 + Al 2 O 3 + B 2 O 3 + P 2 O 5 of 30% or more and less than 65%.
The glass is reinforced lens according to claim 7 or 11 B 2 O 3 / Li 2 O is 0.75 or less.
The glass is reinforced lens according to claim 7 or 11 B 2 O 3 / Li 2 O is 0.7 or less.
The glass is expressed in mol% based on oxide,
SiO 2 : 30% to 65%,
Al 2 O 3 : 0% to 20%,
B 2 O 3 : 0% to 40%,
P 2 O 5 : 0% to 20%,
MgO: 0% to 20%,
CaO: 0% to 20%,
SrO: 0% to 10%,
BaO: 0% to 10%,
ZnO: 0% to 20%,
TiO 2 : 0% to 5%,
ZrO 2 : 0% to 10%,
Li 2 O + Na 2 O + K 2 O: 10% to 25%,
Li 2 O: 10% to 20%,
Na 2 O: 0% to 10%,
K 2 O: 0% to 5%,
Nb 2 O 5 : 0% to 10%,
Ln 2 O 3 : 0% to 10%,
La 2 O 3 : 0% to 10%,
Y 2 O 3 : 0% to 5%,
Gd 2 O 3 : 0% to 5%,
Ta 2 O 5 : 0% to 5%,
WO 3 : 0% to 5%
The reinforced lens according to claim 8, wherein SiO 2 + Al 2 O 3 + B 2 O 3 + P 2 O 5 is 65% or more and less than 80% and TiO 2 + Nb 2 O 5 + WO 3 is 10% or less.
The reinforced lens has a water resistance measured according to JOGIS06-2008 according to the Japan Optical Glass Industry Association standard of grade 3 or higher and an acid resistance of grade 3 or higher. Reinforced lens.
The reinforced lens according to any one of claims 1 to 15, wherein the reinforced lens includes an antireflection layer on at least one main surface of the first main surface and the second main surface.
The reinforced lens according to any one of claims 1 to 16, wherein the reinforced lens includes an antifouling coating layer on at least one of the first main surface and the second main surface.
Lens molding of glass containing 30 to 65 mol% of SiO 2 , 10 mol% or more of Li 2 O, 0 to 10 mol% of SrO + BaO, and Li 2 O / (Li 2 O + Na 2 O + K 2 O) of 0.5 or more Molded into the body,
The lens molded body is a reinforced molten salt containing at least sodium nitrate, and the reinforced molten salt contains 25% or more of sodium nitrate in terms of mass%, and contains 95% or more of sodium nitrate and potassium nitrate in total. A method for manufacturing a reinforced lens, in which the chemical strengthening treatment is performed under the condition satisfying the following formula (1) when the chemical strengthening treatment temperature is T (unit: ° C.) and the treatment time is t (unit: time).
30000 <T 1.8 × t 0.5 <50000 Formula (1)