JP2006089596A - Polycarbonate resin composition for light diffusion plate and lighting cover composed of the same composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polycarbonate resin composition which is remarkably excellent in performance balance of light transmissivity, resistance to hydrolysis, light diffusion property, impact resistance, etc., compared with conventional technique without sacrificing excellent characteristics which polycarbonate resin has originally as an illuminating lamp cover material excellent in transparency and to provide a lighting cover, particularly a lighting cover for bathroom lamps. <P>SOLUTION: The polycarbonate resin composition having a light diffusion property comprises (A) 100 pts. wt. polycarbonate resin and (B) 0.1-5 pts. wt. silicone rubber elastomer having a skeleton composed of a bifunctional siloxane unit and a trifunctional siloxane unit and having organic functional groups on the surface. The lighting cover is composed of the resin composition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light diffusing polycarbonate resin composition comprising a polycarbonate resin and a silicone rubber elastic body having a specific structure. In addition, the lighting cover formed by molding the light diffusing polycarbonate resin composition of the present invention has excellent light diffusibility, wet heat deterioration (hydrolysis) and impact resistance, and is particularly suitable for lighting covers for bathroom lamps. Preferably used.

  Polycarbonate resins are excellent in transparency, heat resistance and impact resistance, and are therefore used in various fields such as vehicles, electric / electronics, household goods, and building materials. When used as a lighting cover for a bathroom lamp, not only excellent light transmittance but also light diffusibility, that is, prevention of seeing through the internal light source is required. Moreover, since the said use is used in a hot and humid environment, it is calculated | required to suppress degradation of polycarbonate resin by hydrolysis to the minimum. Furthermore, since such a light cover is often installed at a relatively high place, drop strength (impact resistance) when the product is dropped is often required as one of the required characteristics.

A polycarbonate resin composition that uses calcium carbonate and titanium oxide in combination has already been proposed as an illumination lamp cover material that is milky-half-colored and excellent in transparency. However, it is light transmissive, hydrolyzable, and light diffusive. However, the balance of performance such as impact resistance is not always satisfactory, and improvement has been strongly desired.
Japanese Patent Publication No.57-24816 JP-A-6-32973 Japanese Patent Laid-Open No. 3-86764 JP 2000-169721 A

The present invention is an illumination lamp cover material with excellent transparency, and without sacrificing the original excellent characteristics of polycarbonate resin, light transmittance, hydrolyzability, light diffusibility, impact resistance, etc. The present invention provides a polycarbonate resin composition having an excellent performance balance, and a lighting cover comprising the same, particularly a lighting cover for bathroom lamps.

  As a result of intensive studies in view of the above problems, the present inventor has found that the above problems can be solved by blending a specific amount of a silicone rubber elastic body having a specific structure with a polycarbonate resin, and has reached the present invention. .

That is, the present invention provides a silicone rubber elastic body (B) of 0.1 to 5 weights having a skeleton composed of a bifunctional siloxane unit and a trifunctional siloxane unit and an organic functional group on the surface in 100 parts by weight of the polycarbonate resin (A). The present invention provides a light diffusing polycarbonate resin composition characterized by containing a part, and a lighting cover comprising the same.

  The light diffusing polycarbonate resin composition of the present invention is extremely excellent in light diffusibility, light permeability, hydrolysis, and impact resistance, and therefore can be suitably used as a lighting cover, particularly a lighting cover for bathroom lamps. .

  The polycarbonate resin (A) used in the present invention is a phosgene method in which various dihydroxydiaryl compounds and phosgene are reacted or a transesterification method obtained by reacting a dihydroxydiaryl compound and a carbonate such as diphenyl carbonate. A typical example is a polycarbonate resin produced from 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

  Examples of the dihydroxydiaryl compound include bisphenol 4-, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl-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-3,5-dibromophenyl) propane, 2,2-bis ( Bis (hydroxyaryl) alkanes such as 4-hydroxy-3,5-dichlorophenyl) propane, 1,1- (4-hydroxyphenyl) cyclopentane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3 Dihydroxy diaryl ethers such as 3,3'-dimethyldiphenyl ether, dihydroxy diaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3 ' Dihydroxy diaryl sulfoxides such as dimethyldiphenyl sulfoxide, dihydroxy diary such as 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone Sulfone, and the like.

  These are used individually or in mixture of 2 or more types. In addition to these, piperazine, dipiperidyl hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, and the like may be mixed and used.

  Furthermore, the above dihydroxyaryl compound and a trivalent or higher phenol compound as shown below may be used in combination. 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'-dihydroxydiphenyl) -cyclohexyl] -propane and the like.

  The viscosity average molecular weight of the polycarbonate resin (A) used in the present invention is 10,000 to 100,000. Preferably it is 15000-35000, More preferably, it is 17000-23000, and when manufacturing this aromatic polycarbonate resin, a molecular weight regulator, a catalyst, etc. can be used as needed.

The silicone rubber elastic body (B) used in the present invention comprises a skeleton of a bifunctional siloxane unit represented by the following general formula 1 and a trifunctional siloxane unit represented by the following general formula 2, and further has an organic functional group on the particle surface. Are present.
General formula 1

General formula 2

The ratio of the bifunctional siloxane unit in the skeleton constituting the silicone rubber elastic body (B) of the present invention is preferably 30 to 95% by weight, more preferably 40 to 70% by weight. The larger the ratio of the bifunctional siloxane unit, the lower the glass transition temperature (Tg) of the silicone resin rubber elastic body, and the lower the refractive index.

The trifunctional siloxane unit is preferably 5 to 70% by weight, more preferably 30 to 60% by weight of the siloxane unit constituting the silicone rubber elastic body (B). The trifunctional siloxane unit is used to make the silicone rubber elastic body (B) into a crosslinked structure, and thus the refractive index can be increased.

R ¹ , R ² and R ³ shown in the above general formulas 1 and 2 are organic functional groups, and among them, hydrocarbon groups having 1 to 20 carbon atoms are common. Specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, hexyl group, dodecyl group; phenyl group, benzyl group, tolyl group, naphthyl group; When an aromatic hydrocarbon group is used, the heat resistance of the silicone rubber elastic body (B) is improved and the refractive index is increased.

The silicone rubber elastic body (B) of the present invention can be produced by a known method. First, as described in, for example, “Synthesis and Application of Organosilicon Polymer” (published by CMC Co., Ltd., November 30, 1989), the skeleton is co-hydrolyzed of bifunctional and trifunctional chlorosilanes or alkoxysilanes. There is a method by co-condensation. By selecting an organic functional group directly bonded to Si of chlorosilane or alkoxysilane used at this time, R ¹ , R ² and R ³ can be determined.

What is necessary is just to select the quantity ratio of a bifunctional siloxane unit and a trifunctional siloxane unit with Tg and refractive index of a desired silicone rubber elastic body (B). In addition, −50 to −200 ° C. is suitable for the Tg of the silicone rubber elastic body (B). A refractive index of 1.39 to 1.46 is suitable.

The organic functional group present on the surface of the silicone rubber elastic body (B) of the present invention expresses the affinity between the silicone rubber elastic body (B) and the polycarbonate resin (A). Is an unsaturated alkyl functional group such as vinyl group, allyl group, ethynyl group, propargyl group; ether functional group such as methoxy group, ethoxy group, phenoxy group; formyl group, acetyl group, benzoyl group, acryloyl group Acyl functional groups such as methacryloyl groups; carboxylic acid functional groups such as carboxy groups; ester functional groups such as acetoxy groups, methacryloyloxy groups, acryloyloxy groups, methoxycarbonyl groups, and ethoxycarbonyl groups; Nitrile functional groups such as cyanate groups, cyanate ester functional groups such as cyanato groups, glycidyl groups And epoxy functional groups UNA and the like. Of these, unsaturated alkyl functional groups, ether functional groups, acyl functional groups, ester functional groups, and epoxy functional groups are preferred.

Content of an organic functional group is 0.05 to 10 weight% of the whole silicone rubber elastic body (B). In particular, 0.5 to 10% by weight is preferable.

There is a well-known method for making an organic functional group exist on the surface of the silicone rubber elastic body (B). For example, when the skeleton of the above-mentioned silicone rubber elastic body (B) is configured, the raw material chlorosilane and alkoxysilane R ¹ , R ² , R ³ having the organic functional group are selected. Alternatively, after forming the skeleton of the silicone rubber elastic body (B) using the method described in “Synthesis and Application of Organosilicon Polymer”, first, the hydrocarbon group on the surface is chlorinated, and this is treated with an organic functional group. There is a method of reacting with a Grineer reagent having a group.

The particle size of the silicone rubber elastic body (B) is preferably 0.5 to 10 μm in terms of weight average particle size. More preferably, it is the range of 1-5 micrometers. If the particle size is less than 0.5 μm, the particle size is smaller than the wavelength of light, and thus it may be difficult for light to diffuse. On the other hand, when the thickness exceeds 10 μm, the transmitted light is reduced, the light diffusion performance is deteriorated, and the impact strength of the obtained light diffusing polycarbonate resin composition may be lowered.

The silicone rubber elastic body (B) is easily available as a commercial product such as the Torefill E series manufactured by Toray Dow Corning Silicone.

The compounding amount of the silicone rubber elastic body (B) is 100 parts by weight of the polycarbonate resin (A) and is 0.1 to 5 parts by weight. More preferably, it is 0.5-3 weight part, More preferably, it is the range of 0.5-2 weight part. If the blending amount is less than 0.1 parts by weight, a sufficient light diffusion effect cannot be obtained and the light source can be seen through, which is not preferable. Moreover, when it exceeds 5 weight part, since the light transmittance and hydrolysis resistance of the obtained light diffusable polycarbonate resin composition will fall, it is unpreferable.

The mixing method and order of the polycarbonate resin (A) and the silicone rubber elastic body (B) are not particularly limited, and are mixed using a known mixer such as a tumbler, ribbon bender, high speed mixer, etc. And a melt kneading method using a single screw or twin screw extruder. It is also possible to prepare a master batch of the silicone rubber elastic body (B) using the polycarbonate resin (A) in advance, and mix and knead the polycarbonate rubber (A) with a specified amount, and then melt knead.

  When mixing, known additives such as phenol or phosphorus heat stabilizer [2,6-di-t-butyl-4-methylphenol, 2- (1-methylcyclohexyl) -4, 6-dimethylphenol, 4,4'-thiobis- (6-t-butyl-3-methylphenol), 2,2-methylenebis- (4-ethyl-6-t-methylphenol), n-octadecyl 3- ( 3,5-di-t-butyl-4-hydroxyphenyl) propionate, tris (2,4-di-t-butylphenyl) phosphite, 4,4'biphenylenediphosphinic acid tetrakis (2,4-di-t- Butylphenyl), etc.], UV absorber [pt-butylphenyl salicylate, 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hex ) Oxy] -phenol, 2,2'-dihydroxy-4-methoxybenzophenone, 2- (2'-hydroxy-4'-n-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-t) -Octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl) -2H-benzotriazole, etc.], other light diffusing particles [calcium carbonate, barium sulfate, Clay, kaolin, amorphous silica, crystalline silica, colloidal silica, calcium fluoride, glass, muscovite, talc, mica, aluminum hydroxide, epoxy resin, phenol resin, melamine resin, benzoguanamine, benzoguanamine / formaldehyde condensation resin, benzoguanamine・ Melamine / formaldehyde condensation resin, Cross-linked acrylic resin, urethane resin, cross-linked polystyrene, composite particles composed of melamine resin and silica, composite particles composed of acrylic and silica, etc.], mold release agent [beeswax, glycerol monostearate, montanic acid wax, polyethylene wax, pentaerythritol Tetrastearate, etc.], colorant [titanium oxide and other dyes and pigments], spreading agent [epoxidized soybean oil, liquid paraffin, etc.], monophosphate ester, flame retardant [brominated polycarbonate oligomer, aromatic sulfur-containing metal salt, par Fluorobutanesulfonic acid metal salt, polytetrafluoroethylene, etc.], and other thermoplastic resins such as polystyrene, acrylonitrile / styrene copolymer resin, styrene resins such as maleic anhydride / styrene copolymer resin, polyethylene terephthalate, Polybutylene A terephthalate, amorphous polyester, etc. can be mix | blended as needed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. “Parts” are based on weight.

Details of the materials used in the examples are as follows.
(A) Polycarbonate resin (hereinafter abbreviated as PC)
Caliber 200-13 (molecular weight: 20500) manufactured by Sumitomo Dow
(B) Silicone rubber elastic body (hereinafter abbreviated as Si-E)
TORAYFIL E-604 made by Toray Dow Corning Silicone
(Average particle size: 2 μm)
(C) Calcium carbonate (hereinafter abbreviated as CaCO ₃ )
Maruo Calcium CUVE7OA (average particle size: 6 μm)

  Based on the formulation shown in Table 1, various materials were dry-mixed with a tumbler, and then melt-mixed at 240 ° C. with a Kobe Steel 37 mmφ twin-screw extruder to be pelletized. The following measurements were performed using the pellets of the various compositions obtained.

1. Transmittance Using the obtained pellets, a three-stage plate having thicknesses of 1, 2, and 3 mm was molded using a 100-ton injection molding machine manufactured by Toshiba Machine under the condition of a melting temperature of 300 ° C. Using the plate having a thickness of 2 mm, transmittance T% was measured with a haze meter (HR-100, manufactured by Murakami Color Research Laboratory). A transmittance T% of 35% or more was regarded as acceptable.

2. Light diffusivity Using the 2 mm portion of the plate used in 1 above, the light diffusivity (D ₅₀ ) was determined by an automatic variable angle photometer (Goniophotometer GP-1R manufactured by Murakami Color Research Laboratory). The detailed measurement method is as follows.
Apply a straight beam from the light source of the automatic goniophotometer from the normal direction of the test piece, measure the intensity of the transmitted light with a movable receiver, and plot the transmittance against the angle from the normal direction. The angle (D ₅₀ ) at which the transmittance was 50% of the straight light transmittance was determined. The unit is “degree”, and the light diffusivity (D ₅₀ ) is 45 degrees or more.

3. Hydrolysis resistance Using the obtained pellets, a three-stage plate having thicknesses of 1, 2, and 3 mm was molded under the condition of a melting temperature of 300 ° C. by a Toshiba Machine 100-ton injection molding machine. The plate is exposed to 125 ° C. × 100% relative humidity in a pressure cooker (TPC-411) manufactured by Tabay Espec, and is subjected to wet heat degradation for one day and night. The test piece before and after the exposure was dissolved in dichloromethane, and NO. Filter the insoluble matter in the solution using 1 filter paper. The filtrate is dried up, and a certain amount (0.25 g) of the obtained polymer is dissolved in 50 ml of dichloromethane. The viscosity of the dilute dichloromethane solution was measured using a Canon-Fenske viscometer, and the viscosity average molecular weight of the polycarbonate resin was determined using the Schnell equation. As a measure of hydrolysis resistance, the measured viscosity average molecular weight before and after exposure was expressed as a molecular weight decrease calculated based on the following formula. A molecular weight decrease of 3500 or less was accepted.
Reduced molecular weight: (Molecular weight of plate before exposure)-(Molecular weight of plate after exposure)

4). Izod impact strength Using the obtained pellets, a test piece for measuring the impact strength having a thickness of 3.2 mm was molded on a 100-ton injection molding machine manufactured by Toshiba Machine under the condition of a melting temperature of 300 ° C. Using this test piece, the Izod impact strength at a measurement temperature of 23 ° C. was measured according to ASTM D256 standard. An Izod impact strength of 50 kg-cm / cm or higher was regarded as acceptable.

  As shown in Table 1, for each of the blending components and those blending amounts that satisfy the constituent requirements of the present invention (Examples 1 and 2), all the evaluation items satisfied the standards and passed. It was. On the other hand, those not satisfying the configuration of the present invention (Comparative Examples 1, 2, and 3) had their respective defects.

In Comparative Example 1, since the amount of the light diffusing particles is less than the lower limit of the defined range, the diffusion degree D ₅₀ had failed.

  In Comparative Example 2, since the blending amount of the light diffusing particles exceeded the upper limit of the specified range, the transmittance T% and the hydrolysis resistance (molecular weight reduction amount) did not satisfy the standard.

Comparative Example 3 is an example in which calcium carbonate is blended in the light diffusing particles, but the light diffusibility, impact resistance, and hydrolysis resistance (molecular weight reduction amount) did not satisfy the standards.

Claims (4)

100 parts by weight of the polycarbonate resin (A) contains 0.1 to 5 parts by weight of a silicone rubber elastic body (B) having a skeleton composed of a bifunctional siloxane unit and a trifunctional siloxane unit and an organic functional group on the surface. A light diffusing polycarbonate resin composition characterized by that. The light-diffusing polycarbonate resin composition according to claim 1, wherein the silicone rubber elastic body (B) has a weight average particle diameter of 0.5 to 10 μm. An illumination cover formed by molding the light diffusing polycarbonate resin composition according to claim 1. An illumination cover for a bathroom lamp formed by molding the light diffusing polycarbonate resin composition according to claim 1 or 2.