JP2007204554A - Optical resin molding, and light guide plate and light diffusion plate comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical resin molding, typically a light guide plate or a light diffusion plate, having excellent heat resistance, excellent non-hygroscopicity, and reduced warp and deformation under high-temperature and high-humidity. <P>SOLUTION: The optical resin molding (a light guide plate or a light diffusion plate) is molded from a resin composition comprising 5 to 95 wt.% copolymer (A) comprising 1 to 10 wt.% alkyl (meth)acrylate monomer and 99 to 90 wt.% aromatic vinyl monomer and having a polystyrene-equivalent weight-average molecular weight of not smaller than 100,000 and a molecular weight distribution Mw/Mn of 1.8 to 3.0 and 95 to 5 wt.% polycarbonate resin (B). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical resin molded article having good heat resistance and hygroscopicity, and more particularly to a light guide plate and a diffusion plate comprising the same.

Acrylic resins are widely used in outdoor applications such as automobile exterior parts and exterior products because of their excellent transparency, light resistance, and surface hardness. Acrylic resin is one of the plastics that is optically very excellent because it has a light transmittance in the visible light region that is more than that of glass and has a small birefringence after molding. For this reason, acrylic resins have been conventionally used as various optical materials, and their application as optical parts such as optical plastic lenses, optical discs, and light guide plates is progressing.
However, although acrylic resin is excellent in transparency and moldability, it is known that defects such as warpage and dimensional change of a molded product caused by low impact strength and moisture absorption due to long-term use occur. Furthermore, due to the lack of heat resistance, there is a problem that the molded product easily deforms depending on the use conditions.
To solve these problems, replacement with polycarbonate resin has been proposed, but there are problems such as a decrease in optical properties or a decrease in moldability due to an increase in price or a decrease in birefringence, so that sufficient problems can be solved. Has not reached.
It has also been proposed to use a styrene- (meth) acrylic ester copolymer comprising an acrylic monomer and a styrene monomer (Patent Document 1: Japanese Patent Application Laid-Open No. 2003-165895). The improvement of the warp due to is insufficient.
Furthermore, an alloy of a polycarbonate resin and a styrene- (meth) acrylic acid ester copolymer (Patent Document 2: Japanese Patent Application Laid-Open No. 2004-189805) has been proposed, but it is still satisfactory because of insufficient transparency. At present, nothing is available.
JP 2003-165895 A JP 2004-189805 A

  An object of the present invention is to provide an optical resin molded article (particularly a light guide plate and a diffusion plate) having good heat resistance and moisture absorption.

As a result of intensive studies in view of such problems, the present inventors have found that the above object can be achieved by using a specific copolymer composed of a specific monomer composition and a polycarbonate resin. Has been reached.
That is, the present invention has a polystyrene-reduced weight average molecular weight of 100,000 or more and a molecular weight distribution Mw / Mn of 1.8 to 3.0 (meth) acrylic acid alkyl ester monomer 1 to 10% by weight and aromatic vinyl. Heat resistance and hygroscopicity obtained by molding a resin composition consisting of 99 to 90% by weight of a copolymer (A) 5 to 95% by weight and a polycarbonate resin (B) 95 to 5% by weight The present invention provides an optical resin molded product that is excellent in performance.

  The optical resin molded product obtained in the present invention is excellent in heat resistance and hygroscopicity, so it can suppress warping and deformation of the product under high temperature and high humidity, and has high industrial value. In particular, it can be used effectively as a light guide plate or a diffusion plate.

The present invention will be described in detail below.
The optical resin molded product in the present invention has a polystyrene-reduced weight average molecular weight of 100,000 or more and a molecular weight distribution Mw / Mn of 1.8 to 3.0 (meth) acrylic acid alkyl ester monomer 1 to 10 weight. Obtained by molding a resin composition comprising 5 to 95% by weight of a copolymer (A) consisting of 99% to 90% by weight and an aromatic vinyl monomer and 95 to 5% by weight of a polycarbonate resin (B) It is.

As the (meth) acrylic acid ester monomer constituting the copolymer (A) in the present invention, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2 Ethyl acrylate acrylate and the like, and aromatic vinyl monomers include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl-p-methyl styrene, Halogenated styrene, ethyl styrene, p-isopropyl styrene, pt-butyl styrene, 2,4-dimethyl styrene, divinyl benzene, etc. are exemplified, and one or more types can be selected and used. is there. Among these, methyl acrylate, butyl acrylate, methyl methacrylate, and butyl methacrylate are particularly preferable as the (meth) acrylic acid ester monomer, and styrene is preferable as the aromatic vinyl monomer.
In the present invention, monomers that can be copolymerized with these monomers within a range that does not impede its purpose, for example, vinyl cyanide monomers such as acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile, etc. , Maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and (anhydrous) maleic acid, and epoxy group-containing monomers such as glycidyl methacrylate It is also possible to select one or more types for use.

  It is important that the content of the (meth) acrylic acid ester monomer in the copolymer (A) in the present invention is in the range of 1 to 10% by weight. When the content is less than 1% by weight (the aromatic vinyl monomer exceeds 99% by weight) or exceeds 10% by weight (the aromatic vinyl monomer is less than 90% by weight), the polycarbonate resin (B ), The transparency characteristic of the present invention is greatly impaired. Preferably, it is 2 to 8% by weight of (meth) acrylic acid alkyl ester monomer and 98 to 92% by weight of aromatic vinyl monomer.

  In addition, it is important that the copolymer (A) in the present invention has a polystyrene-equivalent weight average molecular weight of 100,000 or more and a molecular weight distribution Mw / Mn in the range of 1.8 to 3.0. When the weight average molecular weight in terms of polystyrene is less than 100,000, the difference in melt viscosity with the polycarbonate resin is large, so that appearance defects in the final product are likely to occur, and the molecular weight distribution Mw / Mn is 1.8 to 3.0. Deviating from the range is not preferable because the product strength tends to be impaired.

  The copolymer (A) in the present invention can be produced by a known polymerization method. Among them, a bulk polymerization method or a solution polymerization method is preferable, and a continuous bulk or solution polymerization method is more preferably used. . More specifically, a raw material in which a (meth) acrylic acid ester monomer, an aromatic vinyl monomer, and, if necessary, a solvent such as ethylbenzene, toluene, methyl ethyl ketone, etc., is supplied to the polymerization step, After the step of polymerizing the monomer and after the step, the mixed liquid containing the polymer, the unreacted monomer and / or the solvent is heated, and simultaneously or after heating, the mixture is introduced into the decompression chamber and the unreacted monomer and / or Or the separation and recovery process for separating the solvent from the polymer, and further pelletizing the polymer discharged from the recovery process by adding additives such as colorants, antioxidants, and diffusing agents as necessary. It is preferable to consist of the granulation process.

As a method for adjusting the polystyrene-equivalent weight average molecular weight (100,000 or more) and molecular weight distribution (Mw / Mn 1.8 to 3.0) of the copolymer (A) in the present invention, the polymerization method, polymerization temperature, or It can be adjusted by appropriately setting the amount of the polymerization initiator and molecular weight regulator used.
The polystyrene-converted weight average molecular weight and molecular weight distribution of the copolymer (A) in the present invention can be measured using a Shimadzu high performance liquid chromatography (HSG column) after dissolving the copolymer in tetrahydrofuran. It is.

  Furthermore, the pH of the copolymer (A) in the present invention is preferably 7.0 or less from the viewpoint of product strength as a light guide plate or a diffusion plate. More preferably, it is 6.0 or less. In addition, this pH is arbitrarily adjusted by adding an acid component such as phosphoric acid when mixing the copolymer (A) and the polycarbonate or the amount of the polymerization method and the additive during polymerization. Is possible.

  Furthermore, it is preferable that the alkali metal salt in the copolymer (A) in the present invention is less than 0.1% by weight in terms of product strength as a light guide plate or a diffusion plate, as with pH. In addition, about content of an alkali metal salt, it can adjust arbitrarily by the polymerization method of a copolymer (A), adjustment of the additive at the time of superposition | polymerization, its quantity, or the washing | cleaning method of a copolymer (A). Is possible.

  The polycarbonate resin (B) in the present invention is a polymer obtained by a phosgene method in which various dihydroxydiaryl compounds and phosgene are reacted, or a transesterification method in which a dihydroxydiaryl compound and a carbonate such as diphenyl carbonate are reacted. Representative examples include 2,2-bis (4-hydroxyphenyl) propane; polycarbonate resin produced from “bisphenol A”.

  Examples of the dihydroxydiaryl compound include bisphenol A, bis (4-hydroxydiphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2, 2-bis (4-hydroxyphenyl) octane, bisbis (4-hydroxydiphenyl) phenylmethane, 2,2-bis (4-hydroxydiphenyl-3-methylphenyl) propane, 1,1-bis (4-hydroxy-3) -Tert-butylphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 2,2-bis (4-hydroxy-3,5dibromophenyl) propane, 2,2-bis (4 Bis (hydroxyaryl) alkanes such as -hydroxy-3,5-dichlorophenyl) propane; , 1-bis (4-hydroxyphenyl) cyclopentane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4′-dihydroxydiphenyl ether, 4,4′- Dihydroxy diaryl ethers such as dihydroxy-3,3′-dimethyldiphenyl ether, 4,4′-dihydroxydiphenyl sulfide, dihydroxydiaryl sulfides such as 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfide Dihydroxy diaryl sulfoxides such as 4,4′-dihydroxydiphenyl sulfoxide, dihydro such as 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfone Siji aryl sulfones and the like.

  These may be used alone or in combination of two or more. In addition to these, piperazine, dipiperidyl hydroquinone, resorcin, 4,4′-dihydroxydiphenyls, and the like may be mixed.

  Further, the above-mentioned dihydroxydiaryl compound and a trivalent or higher valent phenol compound as shown below may be mixed and used. Trihydric or higher phenols include phloroglucin, 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -heptene-2,4,6-dimethyl-2,4,6-tri- (4 -Hydroxyphenyl) -heptane, 1,3,5-tri- (4-hydroxyphenyl) -benzol, 1,1,1-tri- (4-hydroxyphenyl) -ethane and 2,2-bis- (4 4 '-(4,4'-hydroxydiphenyl) cyclohexyl) -propane and the like. In addition, when manufacturing these polycarbonate resins, a molecular weight regulator, a catalyst, etc. can be used as needed.

  The optical resin molded product in the present invention is obtained by molding a resin composition comprising the above-mentioned copolymer (A) 5 to 95% by weight and polycarbonate resin (B) 95 to 5% by weight. When the polymer (A) is less than 5% by weight (the polycarbonate resin (B) exceeds 95% by weight), the optical properties and moldability tend to be inferior, and when the copolymer (A) exceeds 95% by weight ( (Polycarbonate resin (B) is less than 5% by weight) This is not preferable because heat resistance tends to be insufficient.

In the present invention, benzotriazole-based ultraviolet absorbers such as Tinuvin P, 234, 326, 329, 360 (manufactured by Ciba Specialty Chemicals), Sumisorb 100, 110, 130 (manufactured by Sumitomo Chemical Co., Ltd.), etc. It is possible to add one or more benzoate ultraviolet absorbers such as benzophenone ultraviolet absorbers and SUMISORB 400 (manufactured by Sumitomo Chemical Co., Ltd.).
These ultraviolet absorbers are preferably blended at a ratio of 0.01 to 5 parts by weight with respect to 100 parts by weight of the resin composition, and sufficient light resistance can be obtained by adding in this range. If the amount exceeds 5 parts by weight, problems such as coloring, deterioration of heat resistance, mold contamination and the like tend to occur, such being undesirable.

Furthermore, in the resin composition of the present invention, as a diffusing agent, for example, inorganic fine particles such as titanium oxide, silica, barium sulfate, and calcium carbonate, and organic cross-linked fine particles made of methacrylic resin, silicon resin and the like can be used. . Although there is no restriction | limiting in particular about the average particle diameter of these diffusing agents, It is preferable that it is the range of 0.1-20 micrometers.
Moreover, it is also possible to add a dye / pigment, a lubricant, a release agent, an antioxidant, and the like as long as the characteristics are not impaired.

  The molding temperature for molding the optical resin molded product of the present invention is preferably 230 to 280 ° C. If the molding temperature is less than 230 ° C., warpage and deformation are likely to occur due to residual molding strain, and if it exceeds 280 ° C., there is a tendency to cause appearance defects due to silver streak or burning, which is not preferable.

  In addition, in order to obtain the optical resin molded product of the present invention, it is molded into various optical resin molded products, particularly a light guide plate and a diffusion plate, by a molding method according to the purpose such as injection molding, extrusion molding, and profile extrusion molding. It is possible.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not restrict | limited at all by these.

〔Example〕
-Copolymer (A)-
Copolymer A-1: An acrylic copolymer was produced using a continuous polymerization apparatus comprising one fully mixed reaction tank having a capacity of 20 liters. 92 parts by weight of styrene as an aromatic vinyl monomer, 8 parts by weight of methyl methacrylate as a (meth) acrylic acid alkyl ester monomer, 0.03 parts by weight of t-dodecyl mercaptan, and t-butyl par as a polymerization initiator Polymerization is carried out by continuously supplying a polymerization raw material consisting of 0.015 parts by weight of oxy (2-ethylhexanoate) and 10 parts by weight of ethylbenzene to the reaction vessel at a rate of 13 kg / h using a plunger pump. The polymerization conversion at the outlet of the reaction vessel was adjusted to 53.5% by weight by adjusting the temperature. The polymerization temperature at this time was 150 ° C. The number of revolutions in the reaction vessel was 150 rpm, and the polymerization temperature was measured by inserting thermocouples in the upper, middle, and lower portions of the reaction vessel. The temperature at the three locations was an average value of ± 0.2 ° C. It is considered that the polymerization liquid is uniformly mixed. Following the polymerization, the polymerization solution continuously drawn out from the reaction vessel is supplied to a devolatilizer to separate volatile components such as unreacted monomers and organic solvents, and then the resin is passed through an extruder. Pelletization was performed to prepare a copolymer A-1.
Polystyrene-converted average weight molecular weight Mw and molecular weight distribution Mw / Mn were measured using high-performance liquid chromatography (manufactured by Shimadzu Corporation) and Shimadzu HSG column in 0.02 g of the obtained copolymer dissolved in 10 ml of THF (hereinafter the same) When measured by a method), they were 200,000 and 2.1, respectively. Further, the polymer was incinerated, dissolved in pure water, and quantified by ICP method and atomic absorption method (hereinafter measured by the same method). The content of alkali metal salt was 0.003% by weight, 1 g of the combined product was dissolved in 40 ml of acetone, then 40 ml of methanol and 40 ml of pure water were added, and the pH of the supernatant obtained by allowing to stand for 1 hour was measured (hereinafter measured by the same method) and found to be 6.3. .

  Copolymer A-2: Copolymer A-2 was prepared in the same manner as Copolymer A-1, except that 5 parts by weight of methyl methacrylate, 95 parts by weight of styrene, and 0.01 parts by weight of t-dodecyl mercaptan were used. Created. The copolymer A-2 had Mw of 250,000, Mw / Mn of 2.2, an alkali metal salt content of 0.002% by weight, and a pH of 6.4.

  Copolymer Ai: Copolymer-i was prepared in the same manner as Copolymer-1, except that 20 parts by weight of methyl methacrylate, 80 parts by weight of styrene, and 0.02 parts by weight of t-dodecyl mercaptan were used. . The copolymer Ai had an Mw of 240,000, an Mw / Mn of 2.2, an alkali metal salt content of 0.003% by weight, and a pH of 6.4.

  Copolymer A-ii: A copolymer A-ii was prepared in the same manner as the copolymer A-1, except that 100 parts by weight of styrene and 0.00 part by weight of t-dodecyl mercaptan were used. The copolymer A-ii had an Mw of 280,000, an Mw / Mn of 2.1, an alkali metal salt content of 0.002% by weight, and a pH of 6.4.

  Copolymer A-iii: A nitrogen-replaced glass reactor was charged with 110 parts of pure water and heated to 70 ° C. Thereafter, an emulsifier aqueous solution in which 1.0 part of potassium oleate was dissolved in 20 parts of pure water and a monomer mixture consisting of 5 parts by weight of methyl methacrylate, 95 parts by weight of styrene and 0.01 part by weight of t-dodecyl mercaptan was added for 4 hours. Over a period of time. Thereafter, the polymerization was continued for 3 hours to complete the polymerization. After completion of the polymerization, 5 parts of 10% aqueous sodium hydroxide solution is added per 100 parts by weight of copolymer latex (solid content), and then salted out, dehydrated and dried using magnesium sulfate to obtain copolymer A-iii. It was. The copolymer A-iii had an Mw of 260,000, an Mw / Mn of 2.5, an alkali metal salt content of 0.85% by weight, and a pH of 8.9.

-Polycarbonate resin (B)-
B-1: Caliber 200-20 (manufactured by Sumitomo Dow)

-UV absorber (C)-
C-1: TINUVIN P (Ciba Specialty Chemicals)

Examples and comparative examples
About each said component, it mixed in the ratio shown in Table 1, and the predetermined | prescribed pellet was obtained with the twin-screw extruder (Nippon Steel Works TEM-35) which set the cylinder temperature to 240 degreeC. The obtained pellets were pre-dried at 100 ° C., and then various test pieces were obtained at a cylinder temperature of 260 ° C. using an injection molding machine (J-150EP manufactured by Nippon Steel). The results are shown in Table 1. Various test conditions are as follows.

Heat resistance : The deflection temperature under load was measured according to ISO 75 under the condition of 0.46 MPa. Unit: ° C
Hygroscopicity : A 12-inch light guide plate (thickness 2 mm) was molded, and the amount of warpage was measured when left in a thermostatic chamber at 55 ° C. and 80% relative humidity for 500 hours. Unit: mm
Transparency : A flat plate of 100 × 50 × 3 was prepared, and haze was measured using a haze meter (HM-150 Murakami Color Research Laboratory).

  Optical resin molded products (especially light guide plates and diffuser plates) in the present invention are excellent in heat resistance and moisture absorption characteristics, and therefore can suppress warpage and deformation of products under high temperature and high humidity, so that the light guide plate has high industrial value. Alternatively, it can be used as various optical resin molded products including a diffusion plate.

Claims (6)

A polystyrene-reduced weight average molecular weight of 100,000 or more and a molecular weight distribution Mw / Mn of 1.8 to 3.0 (meth) acrylic acid alkyl ester monomer 1 to 10% by weight and aromatic vinyl monomer 99 An optical resin molded article obtained by molding a resin composition comprising 5 to 95% by weight of a copolymer (A) consisting of ˜90% by weight and 95% to 5% by weight of a polycarbonate resin (B). The optical resin molded product according to claim 1, wherein the pH of the copolymer (A) is less than 7. The optical resin molded article according to claim 1, wherein the content of the alkali metal salt in the copolymer (A) is less than 0.1% by weight. Optical resin formed by molding a resin composition obtained by further blending 0.01 to 5 parts by weight of the ultraviolet absorber (C) with respect to 100 parts by weight of the resin composition according to any one of claims 1 to 3. Molding. A light guide plate comprising the optical resin molded product according to claim 1. A diffusion plate comprising the optical resin molded product according to claim 1.