JPH0968679A - Spectacle lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the reflected light of a front face by forming a fine concave faces and/or convex face of a radius of curvature within a specific range on at least one face of the front surface, rear surface or boundary of a resin lens. SOLUTION: The superfine particle surface on the convex face side are subjected to sufficient washing, then to the vacuum vapor deposition of nickel and further to nickel plating. A mold is rotated in liquid in order to make the thickness of the nickel plating layer 6 uniform. The mold is taken out of a plating cell when the plating layer 6 attains a prescribed film thickness. The mold is then subjected to washing and drying and a mold 7 having the same curved surface as the curved surface of the plating layer 6 is adhered thereto. Such force as to part the mold 7 is applied thereon to separate the vacuum vapor deposited layer from the superfine particle surface. Ordinary cast polymn. is executed by using the mold 7 and nickel plating part obtd. in such a manner as a stamper 8, by which the lens 1 having the finely rugged surface 2 is obtd. The finely rugged surface having the radius of curvature of 15 to 150nm is formed on at least the one surface of the front surface, rear surface or the boundary of such lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a plastic lens for spectacles and a manufacturing method thereof.

[0002]

2. Description of the Related Art Eyeglasses are required not only for correction but also for protection from foreign matter and light rays and fashionability, and light and thin lenses are constantly required. Colored lenses are considered to be suitable for fashionability. There is. With the development of polymer materials with high refraction and excellent transparency, the demand for plastic lenses exceeds that of glass lenses. The performance required for plastic lenses is, first of all, high transparency as a lens, high refraction and low dispersibility, light weight, safety, dyeability, moldability, etc., as well as reducing the light reflected from the lens surface and increasing the transmittance. That is also important. Generally, the reflected light on one surface of the lens surface is 3% to 4%, and the reflected light tends to increase as the refractive index of the material increases. At present, the method of reducing the reflected light is to form a thin metal film in multiple layers and interfere the reflected light in each layer with each other to eliminate the reflected light.
Antireflection layers ranging from one to seven layers are used. The formation of this antireflection layer is performed using a vacuum vapor deposition device, but an extremely large vapor deposition device is required to process a large number of lenses, and running costs as well as running costs are factors that increase lens costs. Has become.

A technique for reducing the reflected light at the interface between a transparent material having a smooth surface and air can achieve the object by continuously changing the average refractive index between the air and the surface of the transparent material. it can. This idea is solved by forming a heterogeneous film on the surface of the transparent material. In consideration of this non-uniform antireflection principle, in the case where there is unevenness as shown in FIG. 9 as an example, the refractive index (nf (x)) can be expressed by one equation, where x is the depth direction of this layer. .

[0004]

Nf (x) = ng · V (x) + n ₀ (1-V (x)) (1)

Where ng is the refractive index of glass, V (x)
Is the volume occupied by the glass at x, and n ₀ is the refractive index of air. In this case, the refractive index changes discontinuously at the interface between the air and the film and at the interface between the film and the glass substrate, as shown in FIG. 10. Therefore, assuming that the refractive indices at this point are n ₁ and n ₂ , respectively. The reflectance R of the layer can be expressed by Equation 2.

[0006]

[Equation 2]

In this equation, n ₀ = 1.0, n ₁ =
When 1.1, n ₂ = 1.477 and ng = 1.53, the lowest reflectance is obtained when the surface unevenness is 100 nm. However, it is very difficult to form such fine irregularities. In order to solve this problem, by directly coating the surface of the transparent substrate with ultrafine particles in a film form,
Japanese Patent Application Laid-Open No. 2-175601 discloses an antireflection member that satisfies both low reflectance and transmittance. Further, by arranging the SiO ₂ ultrafine particles having a small variation in particle size and a single layer on the glass substrate, the transmittance is improved and an excellent antireflection effect is obtained.

In order to immobilize ultra-fine particles of SiO ₂ on a glass plate in a single layer, the glass plate was mixed with ethyl silicate, ethanol, IPA, MEK and the like, and water and nitric acid for hydrolyzing the ethyl silicate were mixed. Solution (S40
8. Asahi Glass Co., Ltd. and SiO with a particle size of 120 nm
Dip ₂ into a mixed solution of 20% decomposed in ethanol,
After vertically elevating at a rate of 0.98 mm per second to evaporate volatile components, it is baked in air at 150 ° C. for about 30 minutes to decompose tetraethoxysilane. Si produced by decomposition
It is firmly fixed in a continuous and uniform thin film of O ₂ .

FIG. 11 shows SiO ₂ fixed on a glass plate.
The pattern in which the ultrafine particles are fixed as described above is schematically shown as a cross section. The position shown by A in the figure has a refractive index n ₀ of air and its value is 1. At the position shown in B, the refractive index n of the ultrafine particles 4 is equal to 1.48. Therefore, the refractive index of the portion surrounded by A and B is based on the above-mentioned formula 1, and the average refractive index is It can be considered that it continuously changes depending on the ratio of the volume of the SiO ₂ portion to the entire volume of the plate. The refractive index at the position C slightly inside the A was n ₁ , the position at which the volume of the ultrafine particles of SiO ₂ occupied about 100% was B, and the refractive index was ng. The condition that the reflectance R of the glass surface is minimum when the refractive index at the position D is n ₂ is given by the following equation.

[0010]

(Equation 3)

From this, antireflection performance can be obtained when the condition of ng = n ₂ / n ₁ is satisfied. Here, the value of n ₂ / n ₁ is determined by the shape of the unevenness. Here, since n ₁ and n ₂ are numerical values determined according to the ratio of the volume inside the virtual microplate, it seems that they are unrelated to the diameter of the ultrafine particles, but when examined experimentally, the diameter is smaller than around 30 nm. On the other hand, due to manufacturing problems, the uneven surface becomes smooth and the function of suppressing the reflected light is lost. On the other hand, when the diameter is larger than around 300 nm, the transparency becomes cloudy and the transparent feeling of the transparent body is felt. I can't get it. As described above, the thickness of the ultrafine particles arranged in a single layer has the best antireflection function in the vicinity of 100 nm.

There is no problem in fixing a single layer of SiO ₂ on a glass plate, but when fixing these ultrafine particles on a transparent resin plate, for example, on a general-purpose transparent plate such as an acrylic plate or a polycarbonate plate. There are no binders that give strong adhesion to the. Further, in optical materials used for lenses and the like, for example, CR-39 and urethane resin, no suitable binder is found. Therefore, as a means for forming a minute uneven surface on the transparent resin body, an attempt was made to directly transfer the single-layer ultrafine particle surface to the resin body, and the result was shown in Japanese Patent Application No. 5-330768 by the present applicant.

Although the above-mentioned method can achieve a certain result by accurately transferring the transfer surface, when the transfer is repeatedly performed, it is difficult to remove the ultrafine particles and release, and the uniformity of the transfer surface. It caused problems and required further improvements. When the amount of the binder is increased to prevent the particles from falling off, the ultrafine particles become embedded in the binder, and the effect of continuously changing the refractive index decreases. Further, in order to transfer the shape of the ultrafine particles as accurately as possible and reproduce the radius of curvature of the particles, it is preferable that the amount of the binder is small. In terms of the degree of difficulty of mold release, a new matrix is desired because the resin flows between the particles and there is a portion exhibiting an anchor effect, which requires a large force for mold release and leads to damage to the matrix.

[0014]

The problem to be solved is to obtain a lens in which the reflected light on the surface is reduced by transferring by using a new matrix for transferring the ultrafine particle surface arranged in a single layer. That is.

[0015]

The present invention provides a spectacle lens by forming a fine concave surface and / or a convex surface having a radius of curvature of 15 nm to 150 nm on at least one surface of a resin lens, a front surface, a back surface, or an interface.

Another method is to transfer and form fine concave and / or convex surfaces using a stamper.

[0017]

Example 1 FIG. 1 is a schematic view showing a cross section of an eyeglass lens to which an ultrafine particle surface is transferred. Reference numeral 1 is a lens body, and 2 is a transfer surface of a single layer ultrafine particle surface. FIG. 2 shows a glass mold 3 for casting polymerization, which has a particle size of 120 nm of SiO 2.
₂ Ultrafine particles are firmly fixed by the method described above. In order to mold the lens 1 shown in FIG. 1, after the superfine particle surface 5 on the convex surface side shown in FIG. 2 is sufficiently washed, vacuum deposition of nickel is performed, and then nickel plating is performed to form the thickness of the nickel plating layer. The mold is rotated in the liquid to make the thickness uniform. When the plating layer 6 has a predetermined film thickness, it is taken out from the plating tank, washed and dried to obtain the plating layer 6
The mold 7 having the same curved surface as the curved surface of 1 is adhered (FIG. 4). A force that separates the molds 7 and 3 is applied to separate the vacuum-deposited layer and the ultrafine particle surface. A part of the separated mold 7 side is enlarged and shown in FIG. The mold 7 and the nickel-plated portion thus obtained are stamped 8
As a result, ordinary casting polymerization is carried out to obtain a lens 1 having a fine uneven surface 2 as shown in FIG. It is possible to create a second stamper that further transfers the transfer surface composed of the nickel-plated layer, and in this case, the shape of the surface naturally becomes the reverse shape.

When a minus lens for spectacles as shown in FIG. 1 is molded by using a high refractive index polyurethane resin and a refractive index of 1.66 as a resin for molding a lens and the reflectance of one surface is measured, it is as shown in FIG. The reflectance was shown. In this case, the reflectance is about 0.3% in the wavelength range around 500 nm to 550 nm where the eyes feel the strongest light, and the reflectance of the metal thin film formed by vacuum vapor deposition increases near this range, whereas It becomes almost flat in the light range. The color of the reflected light on the objective side surface of the lens obtained in this example is purple. or,
In this example, the particle size is 120 nm, but the particle size can be arbitrarily set between 30 nm and 300 nm, and therefore the reflectance characteristics can be changed.

In order to improve the scratch resistance of the fine uneven surface described above, a silicon-based hard coat material may be applied, but the uneven surface may become a smooth surface, and continuous refraction may occur. You cannot change the rate. As a solution to such a problem, first, a lens 1 shown in FIG. 1 is formed by an ordinary mold, and an adhesive layer 9 for improving adhesion as shown in FIG. 7 is formed on the surface thereof, and then a silicon hard coat layer 10 is further formed. The stamper 8 is applied to a thickness of 1 μm to 1.5 μm.
Press with. In this case, it is necessary to carry out the process in a vacuum chamber because the air on the fine uneven surface of the stamper is entrained and a uniform transfer surface cannot be obtained. Actually, since this method requires more steps, the work can be simplified by applying the hard coat liquid to the stamper, pressing the sticker surface 9 and pushing out the extra hard coat liquid. By heating and drying the stamper in a pressed state and removing the stamper, it is possible to form the fine uneven surface 11 having scratch resistance (FIG. 8).

The hard coat layer formed by this method has the effect of scattering the reflected light generated at the interface between the adhesive layer and the lens, and the surface of the hard coat layer has a refractive index of 1.38 MgF.
It is possible to further reduce the reflected light by further vacuum-depositing ₂ .

[0021]

As described above, since the ultrafine uneven surface for reducing the reflected light of the present invention can be processed at the time of lens molding, the conventional antireflection layer made of a multi-layered metal thin film is unnecessary, and the working process can be simplified. As a result, the manufacturing cost can be reduced. Further, since this method can be applied to the injection molding method, it is possible to continuously process a lens having a function of reducing reflected light. In addition, for the improvement of contamination and water repellency due to hand marks, the fluorocarbon coating material Florard (Sumitomo 3M Co., Ltd.) is effective, and the refractive index is 1.36, which is lower than that of MgF ₂ , and therefore reduces reflected light. Will be advantageous.

[Brief description of drawings]

FIG. 1 is a sectional view of a lens according to the present invention.

FIG. 2 is a glass mold used in the present invention.

FIG. 3 is a sectional view of a glass mold having a plated layer.

FIG. 4 is a sectional view showing a stamper manufacturing process.

FIG. 5 is a partially enlarged sectional view of a stamper.

FIG. 6 is a graph showing the reflectance of the present invention.

FIG. 7 is a cross-sectional view showing one step of the present invention.

FIG. 8 is a cross-sectional view of a lens having a hard coat layer on which fine convex surfaces are formed.

FIG. 9 is a theoretical explanatory diagram of reflected light prevention of the present invention.

FIG. 10 is an explanatory diagram showing a change situation of a refractive index.

FIG. 11 is an explanatory view showing the concept of continuous change of the refractive index of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Lens 2, 2-1 Fine uneven surface 3 Glass mold 4 SiO ₂ Ultrafine particle 6 Nickel plating layer 7 Glass mold 8 Stamper 10 Hard coat layer

Claims (2)

[Claims] 1. A spectacle lens in which at least one of a front surface, a back surface, or an interface of a resin lens has a minute concave surface and / or a convex surface having a radius of curvature of 15 nm to 150 nm. 2. The method for manufacturing a spectacle lens according to claim 1, wherein the fine concave surface and / or the convex surface is transferred and formed using a stamper.