JPH0535655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application The present invention relates to a method for manufacturing plastic lenses.

"Prior Art and its Problems" Plastic lenses are lighter than inorganic glass lenses, have excellent impact resistance, and are dyeable, so they have been frequently used as lenses for glasses and cameras in recent years.

Conventionally, plastic lenses are usually manufactured by a casting method, but at that time, a glass or metal mold is coated with a mold release agent in advance.
Thereafter, a monomer solution is injected, the monomer is polymerized and cured, the lens is released from the mold, and after cleaning, a cured film and an antireflection film are provided.

Methods for forming an antireflection film and a cured film include coating with an organic substance and curing it;
A method of vacuum-depositing an inorganic substance is known.

Although the method of vacuum-depositing inorganic substances can form a dense, hard thin film, it lacks flexibility, and if there is a difference in expansion coefficient with the base material, cracks may occur due to temperature changes. In addition, since plastic is water ^- absorbing, it cannot be heated sufficiently during vacuum evaporation, resulting in an unstable refractive index and variations in the reflected color of the anti-reflection film.
It takes more than an hour to raise the level of productivity,
It has the disadvantage of being uneconomical.

Additionally, many plastic cleansers require a temperature of 120°C.
At higher temperatures, materials that require heat treatment at high temperatures cannot be used for vapor deposition because they yellow or deform. For example, MgF ₂ has traditionally been used as a component of low refractive index films, but it cannot be applied to plastics because it must be heated to about 200°C.

``Purpose of the Invention'' The present invention is capable of efficiently forming an antireflection film made of an inorganic compound by a vacuum deposition method without causing cracks, yellowing, deformation, etc. on lenses, and is limited to the inorganic compounds used. The purpose of the present invention is to provide a method for manufacturing a plastic lens that can be applied without any problems.

"Structure of the Invention" The method for manufacturing a plastic lens according to the present invention involves first treating the surfaces of two molds to be used with a mold release agent, and then applying an antireflection film and a cured film thereon by vacuum evaporation. Next, a monomer liquid is injected into the space formed by the mold and the annular gasket, and the monomer is polymerized.

In the present invention, the mold may be made of glass or metal, and the gasket may be made of any polymer such as polyvinyl chloride, polyvinyl acetate, polyethylene, or silicone rubber. be able to.

To carry out the method of the invention, as described above,
First, the surfaces to be used of two glass or metal molds are treated with a mold release agent. Examples of mold release agents that can be used in the method of the present invention include various silicone mold release agents, fluoroalkylalkoxysilanes, mineral oils, fatty acids, fatty acid esters, fatty acid phosphate esters, and fluorocarbons. Such a mold release agent is applied by a dip coating method, a spin coating method, or the like, and heat treatment is performed as necessary depending on the type of mold release agent used to harden it. Among mold release agents, fluorine-based silicone coating liquid (manufactured by Shin-Etsu Chemical Co., Ltd., KP-801) is particularly preferable, and after applying this liquid by dip coating or spin coating,
Heat and harden.

In the method of the present invention, an antireflection film is formed by vacuum evaporation on the use surface of a mold that has been treated with a mold release agent as described above. There are no particular restrictions on the inorganic compounds that can be used to form the antireflection film, and various oxides, halides, and sulfides, such as MgF ₂ , SiO ₂ , and Na ₃ as low refractive index substances, can be used.
(AlF ₄ ), etc., as medium to high refractive index materials.
_{Al2O3 , CeF3} , mixture of MgO and _{Al2O3 , ThO2} ,
Nd ₂ O ₃ , ZrO ₂ , CeO ₂ , TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ ,
Examples include Y ₂ O ₃ , Yb ₂ O ₃ and ZnS.

Although the antireflection film may be a single layer, it is preferably formed by laminating a plurality of layers having different refractive indexes. The film thickness is selected from any combination of film thicknesses depending on the combination of refractive indexes, but when forming an antireflection film consisting of three layers, the optical film thickness is set to 1/4 and 1/4 of the design reference wavelength (λ). /2 and 1/4 or 1/4, 1/4 and 1/4 are preferable.

In the present invention, the anti-reflection film is formed by applying a vacuum deposition method known per se, but since it is deposited on the surface of a mold made of glass or metal, unlike when depositing on a plastic substrate, it is heated. There are no restrictions on conditions such as temperature, and conditions suitable for the substance to be deposited can be adopted.

After the antireflection films are formed on the use surfaces of the two molds as described above, an inorganic compound that acts as a cured film is similarly deposited by vacuum evaporation. Here, as inorganic compounds that can be used,
Examples include SiO ₂ Al ₂ O ₃ and a mixture of SiO ₂ and Al ₂ O ₃ . Regarding vacuum evaporation, it may be determined as appropriate depending on the substance used. In addition, the film thickness is
The thickness is usually 1 to 10 μm, preferably 2 to 5 μm.

After the anti-reflection film and the cured film are sequentially formed on the surfaces of the two molds, the monomer liquid, which is the raw material for the plastic lens, is poured into the space formed by the two molds and the annular gasket. is injected and polymerized and cured by a method known per se.

Plastics for lenses include, for example, acrylic resins, polycarbonates, diethylene glycol bisallyl carbonate polymers, di(meth)acrylate polymers of (halogenated) bisphenol A and their copolymers, and urethane-modified (monocarbon) polymers of (halogenated) bisphenol A. ) Acrylate polymers and copolymers thereof, polyurethane resins such as urethane resins made of diisocyanate and mercaptoalkyl ester of polyol, etc., but there are no particular limitations.

FIG. 1 shows the state before the mold is released when a plastic lens is manufactured by the method of the present invention. As shown in FIG. 1, a release agent layer 2, a vacuum-deposited layer 3 consisting of an antireflection film and a cured film are sequentially provided on the use surfaces of two molds 1. A plastic lens 5 is cast into the space formed by the mold 1 and the gasket 4.

The plastic lens taken out of the mold after polymerization and curing of the monomers according to the method of the present invention is a product lens already having a cured film and an antireflection film.

"Examples of the Invention" Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, in the examples, "parts" means "parts by weight" unless otherwise specified.

Example 1 A fluorine-based silicon coating solution (KP-801, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surfaces of two glass molds using a dip coating method, and heat treated at 120° C. for 1 hour.

The glass mold with the mold release agent layer formed in this way is placed into a vacuum evaporator, and first SiO ₂ is deposited at λ/4 (λ
A layer with a refractive index n = 1.45 was formed by vacuum evaporation to an optical thickness of λ/4 (λ = 510 nm), and then Ta ₂ O ₅ was vacuum deposited to an optical thickness of λ/4 (λ = 510 nm). A layer with a refractive index n = 2.00 is formed by vapor deposition, and a layer with a refractive index n = 1.86 is further formed by vacuum evaporation of Yb ₂ O ₃ to an optical thickness of λ/4 (λ = 510 nm). Finally, SiO ₂ was vacuum deposited to an actual thickness of 2 μm to form a layer with a refractive index n=1.45.

Diethylene glycol bisallyl carbonate was injected into the space surrounded by the two glass molds with the obtained anti-reflection film and cured film and the annular gasket, and heated at 40°C for 8 hours and at 50°C for 2 hours.
Polymerization was carried out at 70°C for 2 hours and at 80°C for 3 hours, and the mold was released.

The obtained lens molded product was an anti-reflection plastic lens with a total light transmittance of 98.5%.

Example 2 A fluorine-based silicone coating liquid (KP-801, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surfaces of two glass molds using a dip coating method, and heat treated at 120°C for 1 hour.

The glass mold with the mold release agent layer formed in this way was placed in a vacuum evaporator, and first, MgF ₂ was added at λ/4.
A layer with a refractive index n=1.38 was formed by vacuum evaporation to an optical thickness of (λ=510 nm), and then,
TiO ₂ was vacuum-deposited to an optical thickness of λ/2 to form a layer with a refractive index of n=2.08, and further,
Al ₂ O ₃ is vacuum evaporated to an optical thickness of λ/4 to form a layer with a refractive index n=1.65, and finally SiO ₂ is vacuum evaporated to an actual thickness of 2 μm to form a layer with a refractive index n=1.65. =
1.45 layers were formed.

When the same monomer as in Example 1 was injected into the space surrounded by the two glass molds with the obtained antireflection film and cured film and the annular gasket and polymerization was carried out in the same manner, the total light transmittance was A plastic lens with 99.5% antireflection was obtained.

"Effects of the Invention" According to the method of the present invention, a vacuum-deposited film is formed on the use surface of a mold, and this mold is used to mold a plastic lens, so high temperatures can be applied. The type of inorganic compound to be deposited can be selected without restriction, and the plastic lens will not crack, yellow, or deform.

Furthermore, according to the method of the present invention, since the monomer is polymerized in a mold having an antireflection film and a cured film, a plastic lens with good adhesion to these films can be obtained.

Furthermore, according to the method of the present invention, a high degree of vacuum can be rapidly achieved during vacuum evaporation.
It is also excellent in productivity and economy.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a plastic lens manufactured by the method of the present invention before being released from the mold. Explanation of symbols 1...mold type, 2...mold release agent layer,
3...Vacuum deposited layer, 4...Gasket, 5...Plastic lens.

Claims (1)

[Claims] 1. First, the surfaces to be used of the two molds are treated with a mold release agent, and then an antireflection film and a cured film are provided thereon by vacuum evaporation, and then the molds and the annular gasket are formed. A method for producing a plastic lens, which comprises injecting a monomer solution into a space in which the monomer is polymerized.