JPH0319242B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a synthetic resin composition for lenses having a high refractive index and low dispersion. Regarding synthetic resins for lenses that have traditionally replaced inorganic glass,
Various studies have been conducted. Examples of these are polydiethylene glycol bisallyl carbonate (hereinafter referred to as polydiethylene glycol bisallyl carbonate)
(abbreviated as CR-39). Examples include polymethyl methacrylate, polycarbonate, and polystyrene. but
CR-39, polymethyl methacrylate, is lightweight;
It has the advantage of being resistant to impact, but its refractive index is
While polycarbonate and polystyrene have a high refractive index of 1.59, they have the disadvantage of large dispersion. In recent years, research has been conducted to produce resins with high refractive index and low dispersion, and
Publication No. 13747 describes a high refractive index resin composition obtained by copolymerizing di(meth)acrylic esters and (meth)acrylic esters or a styrene monomer. 54−
No. 77686 describes a transparent high refractive index resin composition obtained by copolymerizing a monomer having a chlorine, bromine, or iodine atom in an aromatic ring with carbonates or (meth)acrylic acid esters. The resin composition obtained in this way has a high refractive index of 1.60, low dispersion, and low light transmittance.
It is stated that it is 85% or more. However, monomers containing chlorine, bromine, or iodine in their aromatic rings form solid needle-like crystals at room temperature as the amount of halogen atoms they contain increases, and monomers that contain monomers that contain chlorine, bromine, or iodine in their aromatic rings form solid needle-like crystals at room temperature. The polymer is extremely brittle and unsatisfactory in terms of heat resistance and weather resistance. We, the inventors, investigated the purpose of obtaining a resin for lenses that has a high refractive index and low dispersion, and has excellent transparency, impact resistance, heat resistance, and dyeability.As a result, we found that the main component is tripromophenyl methacrylate. However, by copolymerizing specific monomers in a specific ratio, the remaining monomers in the resin can be reduced. As a result, the resin has a high refractive index and low dispersion, and also satisfies the transparency, impact resistance, heat resistance, weather resistance, etc. desired as a resin for lenses, and has good dyeability. They discovered that it is possible to obtain the following, and completed this invention. That is, this invention is based on the formula

Tribromophene represented by [Formula] 40-70% by weight of methacrylate units, formula

10 to 40% by weight of styrene units represented by [formula] and general formula (1) [In the formula, R represents hydrogen or a methyl group, and n is an integer of 1 to 23. ] 5 to 30% by weight of at least one type of polyethylene glycol di(meth)acrylate unit represented by
A resin composition for lenses having good dyeability and having an Abbe number of at least 33 and a refractive index of at least 1.58. In this invention, the content of tribromophenyl methacrylate units is preferably 40 to 70% by weight,
45-65% by weight is preferred. The higher the content of tribromophenyl methacrylate units, the better the refractive index, hardness, heat resistance, hygroscopicity, and flame retardancy of the resulting resin. If it exceeds this limit, the monomer mixture not only cannot be mixed at room temperature, but also has significantly reduced impact strength and weather resistance. On the other hand, if the content of tribromophenyl methacrylate is less than 40% by weight, the dispersion with respect to the refractive index becomes large and the heat resistance also decreases. The content of styrene units is 10-40% by weight, preferably 15-35%
% by weight is preferred. Styrene unit content is 10
When the amount is less than % by weight, heating is required to dissolve tribromophenyl methacrylate, resulting in poor workability, which tends to cause defects such as polymerization distortion. When the content of styrene units exceeds 40% by weight, not only the heat resistance decreases and dispersion increases, but also the dyeability deteriorates. Monomers constituting the polyethylene glycol di(meth)acrylate unit represented by general formula (1) include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. Examples include those in which the average molecular weight of ethylene glycol di(meth)acrylate and polyethylene glycol moiety is 400, 600,1000. The content of polyethylene glycol di(meth)acrylate units represented by general formula (1) is 5 to 30
% by weight, preferably 10-25% by weight is suitable. If the content of the compound represented by general formula (1) is less than 5% by weight, the resulting resin composition will have insufficient impact resistance, and if it exceeds 30% by weight, the resulting resin will contain unpolymerized residual monomers. Not only does this increase the heat resistance, but also the shrinkage of the polymer increases at the end of polymerization, which tends to cause partial peeling of the resin from the mold surface, resulting in poor surface properties. In the general formula (1), the value of n is preferably in the range of 1 to 23, and among these, the range of 4 to 20 is particularly effective in improving impact properties. When polymerizing the copolymer of the present invention, other unsaturated vinyl compounds copolymerizable with the monomers constituting the three types of units can be used as necessary. This other copolymerizable unsaturated vinyl compound is used to improve the solubility and reduce the dispersion of tribromophenyl methacrylate, and its amount is 10% based on the total amount of the monomer mixture.
% by weight or less. Specific examples of unsaturated vinyl compounds include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and benzyl methacrylate;
Examples include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate, with methyl methacrylate and benzyl methacrylate being particularly preferred. According to the present invention, it is possible to obtain a resin suitably used for lenses, which has the above composition, has an Abbe's number, which is a measure of dispersion, of 33 or more and a refractive index of 1.58 or more. The resin composition of the present invention can be obtained by polymerization in a suitable mold in the presence of a polymerization initiator. Examples of such polymerization initiators include lauroyl peroxide, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxyisobutyrate, t-butyl peroxyvivalate, and t-butyl peroxide.
butyl peroxy-2-ethylhexanoate,
Organic peroxides such as di-t-butyldiperoxyisophthalate or 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1-azobis-1cyclohexane Known radical initiators such as carbonitrile and dimethyl-2,2'-azobisisobutyrate can be used alone or in combination. As described above, the resin composition for lenses of the present invention is similar to the conventionally known CR
-39, not only has a higher refractive index than polymethyl methacrylate and lower dispersion than polycarbonate and polystyrene, but also has the surface properties and surface hardness necessary for a lens resin, and has high impact resistance and excellent processability. Since it not only has high heat resistance but also low moisture absorption, lenses made from this resin composition have excellent morphological stability during use and can be dyed freely. In addition, known ultraviolet absorbers such as salicylic acid esters, benzophenones, and benzotriazoles, mold release agents such as higher alcohols, higher fatty acids, and waxes can be added to this resin composition. The present invention will be specifically explained below with reference to Examples. Example 1 After dissolving 58 parts by weight of tribromophenyl methacrylate in 20 parts by weight of styrene and 5 parts by weight of methyl methacrylate, 13 parts by weight of polyethylene glycol dimethacrylate with n=14 and 2 parts by weight of ethylene glycol dimethacrylate with n=1 were added. Then, 0.1 part by weight of lauroyl peroxide was added and stirred.
Insoluble materials were removed through a filter, and the mixture was poured into a glass plate-making cell prepared by sandwiching a 5 mm vinyl chloride gasket between two plates of flat glass. Thereafter, polymerization was carried out at 80°C for 2 hours, and after being left at 130°C for 2 hours, the mixture was cooled to obtain a flat plate with a thickness of 5 mm. The refractive index of this plate was measured at 25°C using an Atsube refractometer, and it was 1.59, and the Atsube number was 34.8.
It was hot. Furthermore, the total light transmittance was 90% and the Bitskart softening point (VSP) was 145°C or higher. As a measure of the impact resistance of the obtained board, we tried cutting it with a circular saw cutter, drilling holes with a drill press, etc.
It had sufficient workability as a plastic material for lenses. In addition, sufficient dyeability was observed in a dyeing test using commercially available dyes. The outline of the cutter and drill press used in the test is as follows. Circular saw cutter Drilling machine model Outer diameter 255mm Outer diameter 2mm Number of teeth 100 Number of revolutions 500rpm Tooth width 3mm Number of revolutions 2800rpm Rake angle 0°Lead angle 20°Outer diameter nip angle 15°Examples 2-9, Comparative Examples 1-7 Implementation Each composition (5 mm thickness) was prepared in the same manner as in Example 1. The physical property values are shown in Table 1 together with comparative examples, and it is clear that the resin composition of the present invention is excellent as a lens resin.

Claims (1)

[Scope of Claims] 1 40 to 70% by weight of tribromophenyl methacrylate units represented by the formula [Formula], 10 to 40% by weight of styrene units represented by the formula [Formula], and general formula (1) [In the formula, R represents hydrogen or a methyl group, and n is an integer of 1 to 23. ] 5 to 30% by weight of at least one type of polyethylene glycol di(meth)acrylate unit represented by
1. A resin composition for lenses having good dyeability, which is a copolymer consisting of a copolymer having an Abbé number of at least 33 and a refractive index of at least 1.58.