JPS58171445A - Optical resin composition and optical element - Google Patents

Abstract

PURPOSE:The titled composition having low birefringence properties, heat resistance and improved flow properties in molding, comprising a vinyl-based polymer having a dispersion (weight-average molecular weight/number-average molecular weight) and a weight-average molecular weight in a specific range as a main component. CONSTITUTION:An optical resin composition comprising a vinyl-based polymer having <=2.0, preferably <=1.8 dispersion (weight-average molecular weight/number-average molecular weight) and 10,000-1,000,000, preferably 30,000-500,000 molecular weight as a main component (more than 95wt%). Styrene derivative, acrylic acid ester, conjugated nitriles, alkylallyl esters may be cited as a monomer constituting the polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic optical element made by injection molding, pressure molding, etc., and an optical resin composition containing a vinyl polymer as a main component used therein.

Conventional optical resin materials that are transparent and have a relatively high refractive index include polystyrene, styrene-acrylonitrile copolymer, and polycarbonate IrI4, but they have large birefringence and are difficult to use for high-precision light tube elements. It was not satisfactory as a molding resin.

On the other hand, when molding optical elements, the stability of the resin resin material itself is important because thermal decomposition of the resin is observed when melt molding is performed at a relatively high temperature to ensure good fluidity. It's coming. Therefore, it has been desired to develop an optical resin composition with improved fluidity.

In particular, in high N-density optical systems used for reading information using laser light, inertia, etc., it is important that the resin material used as the optical element has no birefringence and has high heat resistance. Improvements were desired.

As a result of intensive research, the inventors have determined @Ill? By using a vinyl polymer having characteristic values within the range i, it is possible to obtain an optical resin composition with improved fluidity, and by molding the composition, it is possible to produce a heat-resistant optical element with low birefringence. I found out what I can get.

An object of the present invention is to provide an optical resin composition and an optical element with low birefringence.

Another object of the present invention is to provide an optical resin composition and an optical element that have heat resistance.

Still another object of the present invention is to provide an optical resin composition with improved fluidity during molding.

This purpose is to have a dispersion value (weight average molecular weight/number average molecular size) of 2.0 or less, and a weight average molecular weight of 10,000 to 100.
Vinyl polymer C within the range of 10,000 yen will hereinafter be referred to as the vinyl polymer of the present invention. ) as a main component. 'Furthermore, an optical element that achieves the above object is characterized by molding an optical resin composition containing the vinyl polymer of the present invention as a main component.

Here, containing the vinyl polymer of the present invention as a main component means containing the vinyl polymer in an amount of more than 95% by weight in the optical resin composition.

In the optical resin composition of the present invention, the dispersion ratio (weight average molecule II/number average molecule is 2.0 or less, preferably 1.8 or less, and the weight average molecular weight is 10,000 to 1,000,000, It is characterized by containing the vinyl polymer of the present invention preferably in the range of 30,000 to 500,000 as a main component.

When the dispersion value of the vinyl polymer of the present invention is larger than 2.0, the molecular weight distribution becomes broad, the viscosity tends to be high during molding, and distortion tends to remain after cooling, so that good properties cannot be obtained. Furthermore, when the weight average molecule f is less than 10,000,
It has no heat resistance and is unstable when melt molded, resulting in a molded product with poor impact resistance, etc. On the other hand, if it exceeds 1 million, it has high viscosity during molding and has poor moldability, making it unsuitable. .

The term "birefringence" as used in the present invention has a general meaning, and refers to the difference between an ordinary wavefront and an extraordinary wavefront in a medium such as a resin through which light propagates! The light is polarized into 9 paths, each with a different speed.1. .

As a result, a phase relationship occurs between each component, and the phase difference changes in proportion to the characteristics of the medium such as resin and the thickness of the plate. The phase difference - is given by φ=hesaku10-eat.

represents.

Therefore, birefringence can be determined by optically measuring this phase difference.

Regarding the fluidity of the optical resin composition of the present invention, in order to increase the melt index value (ZSOR-1133 method), it is generally preferable to reduce the molecular weight of the molding resin. However, if the molecular weight is too small, the heat resistance of the molded product will deteriorate, so the molecular weight distribution of the vinyl polymer of the present invention is That is, the dispersion value (!1 average molecular weight/number average molecular weight) is controlled.

In the vinyl polymer of the present invention, suitable low-resin characteristics are obtained by reducing the dispersion value (average molecular weight/number average molecular weight) and limiting the weight average molecular weight within a certain range.

As a polymerization method for adjusting the vinyl polymer of the present invention to a polymer with a small dispersion value, Japanese Patent Publication No. 40-7050, No. 4
No. 2-17485, No. 47-19687, No. 47-3
Examples include the living polymer polymerization method described in Japanese Patent Publication No. 3274, and the cationic polymerization method described in Japanese Patent Publication No. 53-5908.

In the present invention, the vinyl resin refers not only to a homopolymer of vinyl threads, but also to other polymers that can be copolymerized with vinyl monomers.
Contains copolymer resin with l-mer.

Vinyl type used in the present invention! Examples of polymers include styrene, α-methylstyrene, p-methylstyrene, and p-methylstyrene.
-tert-butylstyrene, p-methoxystyrene,
Alkyl-substituted styrenes such as p-phenylstyrene, chlorostyrene, bromostyrene, iodostyrene, and halogenated styrenes having several halogen substituents on the benzene nucleus, phenoxy group on the benzene nucleus, benzyloxy 5
, alkyloxystyrenes having one or more alkyloxy groups such as t=butoxy group, alkylthiostyrenes having one or more benzene nuclear groups, phenylthio groups, mercapto groups, etc., methyl methacrylate, cyclohexyl methacrylate, adamantyl methacrylate ester, 2-methylcyclohexyl methacrylate, isobornyl methacrylate, glycidyl methacrylate and
A series of acrylic esters used in the polymer synthesis of axes described in Publication No. 1-2519, phenyl methacrylates substituted with one or more halogen atoms in the benzene nucleus, conjugated nitriles such as acrylonitrile and methacrylaterile, ethylene glycol, propylene Preferred are esters of methacrylic acid and polyhydric alcohols such as glycol, diethylene glycol, pentaerythritol, and trimethylolpropane, and alkyl allyl ethers such as allyl diglycol carbonate.

In addition, the optical resin composition of the present invention has the following properties in order to improve light resistance:
It may also contain an ultraviolet absorber. The UV absorber may be one that does not reduce the transmittance in the visible range and does not degrade other resin properties, such as 0-hydroxysalicylic acid phenyl compounds, 0-hydroxybenzophenone compounds, 2-( (0-hydroxyphenyl)-benzotriazole compounds and cyanoacrylate compounds can be used.

Furthermore, 2,6-di-tert-butyl-P is used as a heat stabilizer.
-Cresol, 2,4-di-methyl-6-tert-butyl-
Phenol, 2,2'-methylenebis(4-methyl-6
-tert-butylphenol), 4.4'-butylidenebis(3-methyl-6-tert-butylphenol), 4.
4'-thiobis(3-methyl-6-tert-butylphenol), 1,1,3-)-lis(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, below margin t -But - B
uH -Bu (R'C1j! to C14 alkyl group) may contain dilaurylthiodipropionate, distearylthiodipropionate, diss, thearyl-β, β-thi, etc.

The resin composition of the present invention may contain a plasticizer in order to further improve fluidity during molding. As a plasticizer,
2-ethylhexyl phthalate, n-butyl phthalate, isodecanyl phthalate, tridecanyl phthalate,
Alkyl phthalates such as heptyl phthalate and nonyl phthalate, alkyl esters of dibasic acids such as 2-ethylhexyl adipate, sebacic acid, 2-ethylhexyl, tributyl phosphate, trioctyl phosphate, tricresyl phosphate, triphenyl phosphate , phosphoric acid alkyl esters such as tricylenyl phosphate, epoxidized fatty acid esters such as epoxidized octyl oleate, epoxidized butyl oleate, and other polyester plasticizers,
Any material can be used as long as it functions as a plasticizer, such as chlorinated fatty acid esters.

Also, two or more of these may be used in combination.

In addition, silicone oil, dimethylpolysiloxane, polysiloxane, aliphatic fluorocarbon,
Liquid or solid paraffin, butyl acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, β-chloroethyl acid phosphate, di(2-ethylhexyl) phosphate, ethylene glycol acid phosphate, (2
-Hydroxyethyl) methacrylate acid phosphate, alkyl acrylate oligomer, etc. may be contained.

Molding methods for producing optical elements by molding the resin composition of the present invention include injection molding, compression molding, or a combination of injection molding and compression molding, such as the low-links method, micromolding method, etc. - Any method of molding the resin by melting or semi-melting it can be applied. Among these molding methods, the present invention has a large effect on molding methods in which the degree of birefringence is relatively large in conventional general-purpose resins. Specifically, for example, the present invention is most advantageous in injection molding methods, and is advantageous in combination methods of injection molding and compression molding, and compression molding methods.

In the optical element obtained by molding the optical resin composition of the present invention, the fluidity of the resin composition is improved, and the homogeneity of the resin is good, so there is no distortion due to molding, and there are no complexities. Refraction is reduced, and compared to conventional general-purpose resins,
It is clear that this is an extremely suitable optical element.

According to the optical resin composition containing the vinyl polymer of the present invention as a main component, the change in characteristics of the resulting optical element is improved, but in order to further improve dimensional stability, coating is required on the surface of the molded product. Measures may also be taken to improve the cutting lubricity and, as a result, the dimensional stability.

Optical elements obtained by molding the resin composition of the present invention include so-called lenses such as still cameras, video cameras, telescopes, eye chains, hard contact lenses, and sunlight collecting IU; Elements that perform their functions by transmitting light, such as prisms such as pentaprisms, mirrors such as concave mirrors and polygons, light guide elements such as optical fibers and optical waveguides, and discs such as optical video discs and audio discs. means.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

[Example-1] After completely purging a T-shaped flask equipped with a stirring bar, a thermometer, a nitrogen introduction tube, a dropping funnel, and a cooling tube with nitrogen, the above composition was mixed to prepare an initiator solution, and - Cooled to 60°C. A solution of chlorstyrene in tetrahydrofuran (50%) was added dropwise to this solution at a rate that did not allow the temperature of the solution to rise above 150°C. After completing the dropwise addition, add this solution to 5000 parts by weight of methanol,
When the polymer was deposited and dried temporarily, the weight average molecular weight of the obtained polymer was 32,000, and the dispersion value (My/In) was 1.42. Also, the melt index value of this polymer is 150 R-1133
The speed was 25.611/10 minutes under the conditions of 230°C and 5kgf, and the glass transition temperature (Tg) was 123°C. When this polymer was injection molded at 240'C to obtain a lens molded product with a thickness of 3 mm at the center, a molded product with good homogeneity with a phase lag of 90 degrees in birefringence was obtained. .

[Example-2] A one-bottle flask equipped with a stirring bar, a thermometer, a nitrogen inlet tube, a dropping funnel, and a cooling tube was completely purged with nitrogen, and then 300 parts by weight of dehydrated benzene and boron triborate diethyl etherate were added. 0.5 parts by weight and 0.5 parts by weight of isopropyl peroxydicarbonate yB5 were added, and the mixture was heated to 30°C. A solution of 100 parts by weight of vinylcarbazole dissolved in 300 parts by weight of benzene was slowly added dropwise to this solution, and the temperature reached 50%.
It was cooled to below 'C. The solution polymerized for 6 hours was poured into 2,000 parts methanol to obtain a precipitated polymer. The weight average molecular weight of this polymer is 24
,000, and the variance value was 1.61.

Moreover, the melt index value of this polymer is 22, f
/10 minutes, the glass transition conductivity (Tg) was 152°C, and when this was injection molded at 250°C to obtain a molded product with a thickness of 3 mm at the center, the birefringence was determined by a phase lag of 160 degrees. A molded product was obtained.

[Comparative Example-1] Chlorstyrene was polymerized using ordinary suspension polymerization to obtain a polymer having a weight average molecular weight of 9,000 and a dispersion value of 2.60. The melt index value of this polymer is 459/1
At 0 minutes, the glass transition temperature (Tg) was 88°C. When this polymer was injection molded under the same conditions as in Example 1 to obtain a lens molded product, a molded product with birefringence having a phase lag of 190 degrees was obtained.

[Comparative Example-2] Chlorstyrene was polymerized using commercially available suspension polymerization to obtain a polymer having a polymerization average molecular weight of 1.1 million and a dispersion value of 2.57.

The melt index value of this polymer is 2.0g/10
The glass transition temperature (Tg) was 120°C. When this polymer was injection molded under the same conditions as in Example 1 to obtain a lens molded product, a molded product with a refraction phase delay of 188 degrees was obtained.

[Comparative Example-3] Chlorstyrene was polymerized using normal suspension polymerization to obtain a polymer having a weight average molecular weight of 28,000 and a dispersion value of 2.46. The melt index value of this polymer is 21.5g
/10 minutes, the glass transition temperature (rg) was 114°C. When this polymer was injection molded under the same conditions as in Example 1 to obtain a lens molded product, the birefringence showed a phase lag of 18
A 5 degree molded product was obtained.

[Comparative Example-4] Polyvinyl carbazole polymerized by normal solution polymerization method, weight average molecular weight ff 124,000, dispersion value 2.8
A polymer was obtained. When this polymer was injection molded in the same manner as in Actual Measurement Example 1, the birefringence of the molded product had a phase lag of 300 degrees.

Claims (2)

[Claims] (1) Dispersion value (weighted average numerator maximum/number average numerator odd) is 26
0 or less and having a weight average molecular weight within the range of 10,000 to 1,000,000, as a main component. (2) Dispersion value (weight average molecular weight/number average molecular weight) is 2.
0 or less and a weight average molecular weight within the range of 10,000 to 1 million.