JPS58105102A - Plastic lens - Google Patents

Abstract

PURPOSE:To obtain a plastic lens low in refractive index by polymerizing fluoroalkyl methacrylate. CONSTITUTION:A plastic lens is prepared by polymerizing fluoroalkyl methacrylate represented by structural formula (II) using benzoyl peroxide as a polymn. initiator. Formula (II) is obtained by replacing hydrogen atoms of the alkyl group of alkyl methacrylate including methyl methacrylate having structural formula (I) by fluorine atoms. The refractive index of said polymer is in the range of 1.418-1.493 dependent on the structures of the fluoroalkyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic lens, particularly a plastic lens with a low refractive index.

Plastic lenses have become widely used in optical products because they are lighter than traditional glass lenses, have the potential for mass production, and are expected to be inexpensive. ing. Currently, the materials mainly used as plastic lens materials include diethylene glycol bisallyl carbonate and methyl methacrylate called Acrysilabu for injection molding, and polymethyl methacrylate for injection molding. , polycarbonate, etc. are commonly used, but compared to conventional glass lenses for both casting and injection molding, there are considerably fewer types of materials in practical use. Moreover, in the case of glass lenses, there is a considerable range of dispersion, ranging from low refractive index to high refractive index1, whereas plastic lens materials have a small number of types and have a large refractive index. 1.4
The width is about 9 to 1650, which is extremely narrow compared to glass lenses. This becomes a big problem when designing lenses. For example, in the case of eyeglass lenses, the refractive index is smaller than that of glass lenses, so the center thickness and curvature are large, giving the user a different impression from the appearance of conventional glass glasses. As another example, in camera lenses, microscope lenses, etc., in order to eliminate various aberrations such as chromatic aberration, 2 spherical aberration, and coma aberration, it is possible to combine lenses with different refractive indexes and dispersion, or to use plastic lenses. It is difficult to use this method because there are only a few species. ] From the above, in addition to the currently used plastic lens materials (diethylene glycol hisallyl carbonate-1, polymethyl methacrylate-1, etc.), we have developed lens materials with various refractive indexes and dispersions. Plastic lenses are highly desired.

In view of these points, the present invention provides alkyl methacrylate-1.
It has the same impact resistance as the current plastic lens obtained by RF bonding, has 244 additional requirements such as being transparent and capable of being molded into a '/1 mold, and is made of diethylene glycol. It provides a plastic lens having a lower refractive index than plastic lenses made of bisallyl carbonate or methyl methacrylate.

That is, the present invention focuses on the fact that fluorides have a low refractive index, and the present invention is based on the following structural formula (I) in which hydrogen and fluorine are substituted for the alkyl groups in the side chains of alkyl methacrylates such as methyl methacrylate shown by the following structural formula (I). This is based on the fact that by polymerizing the 70-oloalkyl methacrylate shown in II), a plastic lens meeting the above requirements by 441 can be obtained.

CH2-C(CH3)C00CnHk (I)
However, n is an integer from 1 to 3, k: 2n+1 or 2n.

CH2CH2-C(CH3)C00CnHk-(■), n = integer from 1 to 3, k-2n+1 or = 2n.

The boria 0-oloalkyl methacrylate obtained by polymerizing this noro-oloargyl methacrylate-1 has a structure that is almost the same as that of the alkyl methacrylate (formula (I) above) before fluorine substitution, and is The physical characteristics and transparency remain almost unchanged. The larger the number of fluorine atoms substituted with 1, the lower the refractive index. As the number ζ and n increases, the glass transition point decreases, and when n = 4 or more, it becomes impractical as a plastic lens.

As the polymerization initiator for polymerizing the fluoroalkyl methacrylate, a conventional thermal polymerization catalyst can be used. For example, t-butyl peroxybenzoate, benzoyl peroxide, t-butyl cumyl peroginde, t-
Examples include organic peroxides such as butyl peroxide.

When producing a lens that is even thinner, it is also possible to carry out photopolymerization using a photopolymerization initiator in order to shorten the polymerization time. Examples of the photopolymerization initiator include atentophenone, benzophenone and derivatives thereof, and benzoin argyl ether.

When using these photopolymerization initiators, it is not only possible to use them alone, but also to use them together with a thermal polymerization catalyst to effectively utilize the heat generated from the lamp during ultraviolet irradiation. It is.

In order to facilitate mold release, it is also possible to apply a known mold release agent to the surface of the mold in advance, or to add an internal mold release agent to the resin.

Examples of the present invention will be described below.

(Example) A concave glass mold and a flat glass mold having a radius of 200 m + 711 □ with a diameter of 50 M1 spherical surface were prepared, and a gasket was inserted between the two glass molds so that the edge thickness was 3 wn. On the other hand, 2 parts by weight of benzoyl peroxide as a polymerization initiator was mixed and dissolved in fluoroalkyl methacrylate to form a transparent solution. Pour this liquid between the glass molds,
Thermal polymerization was carried out at 60°C for 3 hours and then at 90°C for 2 hours. The refractive index of the completed plano-convex plastic lens was measured. The results are shown in Tables 1 to 7 of the following table.

As a comparative example, regarding alkyl methacrylate,
A plastic lens was obtained in the same manner, and its refractive index was measured (-7, so this result was also rounded according to numbers 8 to 10 in the following table.

As is clear from the above table, a plastic lens with a low refractive index can be obtained by polymerizing fluoroalkyl acrylate with a polymerization initiator.

As explained above, according to the present invention, it is possible to provide a plastic lens with a lower refractive index than conventional ones, so it can be used when combining lenses with different refractive indexes and dispersions to eliminate various aberrations, etc. This can be expected to have great effects.

Name of agent: Patent attorney Toshio Nakao and 1 other person7

Claims (1)

[Scope of Claims] A plastic lens characterized by using a resin obtained by polymerizing 70-oloalkyl methacrylate represented by the following structural formula. CH2-C(CH3)CoOCnHk-mFm,
n = integer from 1 to 3, k = 2 n + 1 or