JPS59136311A - Resin for lens - Google Patents

Abstract

PURPOSE:To provide the titled resin having high refractive index and small aberration, by polymerizing tribromophenyl methacrylate, methyl methacrylate, polyethylene glycol di(meth)acrylate and brominated phenyl acrylate at specific ratios. CONSTITUTION:The objective resin having an Abbe number of >=34, preferably >=35, and a refractive index of >=1.55, preferably >=1.58 can be prepared by polymerizing a mixture containing (A) 40-90wt%, preferably 50-80wt% of tribromophenyl methacrylate, (B) 5-30wt%, preferably 15-25wt% of methyl methacrylate, (C) 2-30wt%, preferably 5-20wt% of one or more polyethylene glycol di(meth)acrylates of formula (R is H or methyl; n is 1-23) and (D) 3- 40wt%, preferably 5-30wt% of brominated phenyl acrylates having 1-5 Br atoms on the aromatic ring. EFFECT:It has excellent surface hardness, impact resistance, processability, and heat resistance and low moisture absorptivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synthetic resin composition for a lens that has a refractive index of about 100% and has small aberrations.

Various studies have been conducted on synthetic resins for lenses that can replace inorganic glass. Examples of these include polydiethylene glycol-rubisallyl carbonate (hereinafter abbreviated as CR-39), polymethyl methacrylate, polycarbonate, polystyrene, and the like. However, CR-39, polymethyl methacrylate, is lightweight;
It has the advantage of being resistant to impact, but its refractive index is 1.4.
While polycarbonate and polystyrene have a high refractive index of 159, they have the disadvantage of large chromatic aberration.

In recent years, research has been conducted to produce resins with high refractive index and small chromatic aberration, and Japanese Patent Application Laid-open No. 13747/1983 describes di(meth)acrylic esters, (meth)acrylic esters, or styrene monomers. In JP-A-54-77686, there is a description of a high refractive index resin composition obtained by copolymerizing a monomer with a chlorine, bromine or iodine atom in an aromatic ring, and carbonates or (
There is a description of a transparent high refractive index resin composition obtained by copolymerizing meth)acrylic acid esters. The resin composition obtained in this way has a high refractive index of 160,
It is stated that the chromatic aberration is small and the light transmittance is 85% or more. However, monomers with chlorine, bromine, or iodine atoms in their aromatic rings become solid needle-like crystals at room temperature as the amount of halogen atoms they contain increases, and monomers that contain chlorine, bromine, or iodine atoms in their aromatic rings become solid needle-like crystals at room temperature. Degassing is extremely difficult, the polymer is extremely brittle, and its heat resistance and weather resistance are also unsatisfactory. Furthermore, if the above-mentioned monomer is dissolved in (meth)acrylic acid ester, cast polymerization can be carried out in the same process as in the case of a normal liquid upper layer, but even in this case, the content of the above-mentioned monomer is When the amount increases, the impact strength, heat resistance, and weather resistance of the produced polymer also decrease.

We, the inventors, conducted research aimed at obtaining a resin for lenses that has a high refractive index, low chromatic aberration, and has excellent transparency, impact resistance, and heat resistance.As a result, we found a composition that generally has tribromophenyl methacrylate as its main component. However, the remaining monomers in the resin can be reduced by copolymerizing specific monomers in a specific ratio. They discovered that it is possible to obtain a resin that has a high refractive index and low chromatic aberration, and also satisfies the transparency, impact resistance, heat resistance, weather resistance, etc. desired as a resin for lenses.
This invention was completed.

That is, this invention contains 40 to 90% by weight of [A] tribromophenyl methacrylate, based on the total amount of the monomer mixture;
B] Methyl methacrylate 5 to 30% by weight (C) At least one compound represented by general formula (I) 2 to 30% by weight
Weight%0 0
and (D) 3-40% of at least one brominated phenyl acrylate having 1-5 bromine atoms in the aromatic ring
The resin for lenses is characterized in that it has an Abbe number of at least 34 and a refractive index of at least 1.55, obtained by polymerizing a mixture containing the following.

In this invention, the content of tribromophenyl methacrylate is preferably 40 to 90% by weight, preferably 50 to 80% by weight. Tripro and flame retardancy are improved, but
When the content of tribromophenyl methacrylate exceeds 90% by weight, the impact strength decreases significantly, and along with the decrease in the polymerization rate, the heat resistance and weather resistance also decrease. On the other hand, if the content of tribromophenyl methacrylate is less than 40% by weight, the refractive index value is small and the object of the invention cannot be achieved.

The content of methyl methacrylate is preferably 5 to 30% by weight, preferably 15 to 25% by weight.

If the content of methyl methacrylate is less than 5% by weight, not only will it be difficult to dissolve tribromophenyl methacrylate, but it will also be necessary to prevent dissolved tribromophenyl methacrylate from precipitating during various steps such as injection into a mold and degassing. Workability deteriorates as it is necessary to maintain the polymer at a high temperature, and as a result, polymerization distortion and defects are likely to occur.

If the content of methyl methacrylate exceeds 30% by weight, the refractive index and heat resistance will decrease.

Polyethylene glycol di(
As meth)acrylate, diethylene glycol di(
meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate
Examples include those in which the average molecular weight of the acrylate and polyethylene glycol moieties is 400.600.1000.

The content of the compound represented by formula (I) is suitably 2 to 30% by weight, preferably 5 to 20% by weight. General formula (
If the content of the compound represented by I) is less than 2% by weight, the resulting resin composition will have insufficient impact resistance, and if it exceeds 30% by weight, the resulting resin will contain a large amount of unpolymerized residual monomers. Not only does the heat resistance decrease, 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 general formula CI), the value of n is preferably in the range of 1 to 23, and among these, 4 to 23 are particularly effective in improving impact resistance.
The range is 20.

The content of the brominated phenyl acrylate having 1 to 5 bromine atoms in the aromatic ring used in this invention is suitably 3 to 40% by weight, preferably 5 to 30% by weight. If the content of brominated phenyl acrylate is less than 3% by weight, the desired effect of reducing residual monomers will be small, and if it exceeds 40% by weight, although the residual monomers will be reduced, heat resistance will decrease and A partial peeling phenomenon occurs. That is, in the present invention, by using brominated phenyl acrylate having 1 to 5 bromine atoms in the aromatic ring, a high polymerization rate can be obtained without significant decrease in refractive index and transparency.

According to the present invention, it has the above composition, has an Abbe number that is a measure of chromatic aberration of 34 or more, preferably 35 or more, and has a refractive index of 1.
It is suitably used for lenses having a diameter of 55 or more, preferably 1.58 or more. Resin can be obtained.

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 peroxy pivalate,
t'-phthyl baroxy-2-ethylhexanoate,
Organic peroxides such as di-t-butylshiba-oxyisophthalate or 2. z′-azobisisobutyronitrile,
2. Known radical initiators such as '2'-azobis-2,4-dimethylvaleronitrile, 1-azobis-1-cyclohexanecarbonitrile, and dimethyl-2,2'-azobisisobutyrate may be used alone or in combination. can.

As described above, the lens resin composition of the present invention not only has a higher refractive index than conventionally known CR-39 and polymethyl methacrylate, and has smaller chromatic aberration than polycarbonate and polystyrene, but also has a surface area necessary for a lens resin. Lenses made from this resin composition have excellent morphological stability during use because they have high impact resistance, excellent processability, high heat resistance, and low moisture absorption. .

Additionally, known ultraviolet absorbers such as salicylic acid esters, benzophenones, and benzotriazoles, higher alcohols, higher fatty acids, and mold release agents such as wax can be added to this resin composition.

The present invention will be specifically explained below with reference to Examples.

Example 1. ') Ribromophenyl methacrylate s
After dissolving 30 parts by weight of tribromophenyl acrylate in 15 parts by weight of methyl methacrylate while heating at 50°C, 5 parts by weight of n-14 polyethylene glycol dimethacrylate was added, and further 0.05 parts by weight of lauroyl peroxide.
Parts by weight were added and stirred. Insoluble materials were removed through a filter, and the mixture was injected into a glass plate-making cell prepared by sandwiching a vinyl chloride gasket between two flat glasses placed 5 mm apart.

After degassing under reduced pressure, polymerization was carried out at 80°C for 2 hours, and after being left at 130°C for 2 hours, it was cooled to obtain a 511 m flat plate. When the refractive index of this plate was measured at 125°C with an Atsbe refractometer, it was 160, and the Atsbe number was 36.
It was 6. In addition, the total light transmittance is 90%, the residual monomer content is 14%, and the Pickert softening point (v, s, p.

) was 138°C. As a measure of the impact resistance of the obtained plate, cutting with a circular saw cutter, drilling with a drill press, etc. were attempted, and as a result, it was found to have sufficient workability to be used as a plastic material for lenses.

The outline of the cutter and drill press used in the test is as follows.

Circular saw cutter Drilling machine model % Formula % Rake angle 0° Lead angle 20° 1/- Outer diameter rake angle 15° 11 Examples 2 to 9, Comparative Examples 1 to 6 Compositions prepared in the same manner as Example 1 Table 1 shows the physical properties of objects.
Shown below. For comparison, commercially available plastic materials for lenses are also listed. This clearly shows that the composition of the present invention has excellent physical properties.

Table 1 Note: Workability is a comprehensive judgment based on the results of cutting, machining, drilling, etc., and is indicated as ○...Good, Mu...Poor, ×...Severely poor.

TBPMA...tridi-10mophenyl methacrylate B
PM...brominated phenyl acrylate 0 is the number of bromine atoms MMA...methyl methacrylate PEG
MA...Polyethylene glycol dimethacrylate 0 is the value of n CR-39...Polydiethylene glycol bisallyl carbonate pc...Polycarbonate psi...Polystyrene patent 1'1Lit person Kyowa Gas Chemical Co., Ltd. Procedure amendment Document (method) 1. Case evidence Patent Application No. 58-10969 2. Name of the invention Lens resin 3. Person making the amendment 4. Date of amendment order April 6, 1980 April 1988 Sent on the 26th, 5, the descriptions in column 6 of "Detailed Description of the Invention" of the specification subject to amendment, and on pages 1 and 13 of page 42 of the specification of contents of the amendment are corrected as shown in the attached sheet. (There are no changes to the content.)

Claims (1)

[Scope of Claims] 1) [A] tripromophenyl methacrylate 40 to 90] ii 1% CB) methyl methacrylate 5 to 30% by weight based on the total amount of the monomer mixture (C) of the compound represented by general formula (I) The Atsube number obtained by polymerizing a mixture containing 2 to 30% by weight of at least one type of 0 and (2) 3 to 40% by weight of at least one type of brominated phenyl acrylate having 1 to 5 bromine atoms in the aromatic ring is A resin for a lens, characterized in that a refractive index of at least 34 is at least 155.