JP5315015B2 - Polycarbonate resin composition and optical molded article comprising the same - Google Patents

Description

  The present invention does not impair heat resistance, mechanical strength, etc., and further, has no white turbidity or a decrease in light transmittance, has a good hue and brightness, and a light guide plate formed by molding the same. The present invention relates to optical molded products such as illuminant materials and nameplates.

  In the liquid crystal display device, a planar light source device is incorporated in order to cope with demands for thinning, lightening, power saving, high luminance and high definition. This planar light source device is provided with a light guide plate having a wedge-shaped cross section having a uniformly inclined surface. In addition, in order to obtain high luminance, a proposal has also been made to provide a light scattering function by forming a prism-shaped uneven pattern on the inclined surface (Patent Document 1).

  The light guide plate is generally obtained by injection molding of a thermoplastic resin, and the concavo-convex pattern is given by transferring the concavo-convex pattern formed on the mold surface. Conventionally, the light guide plate has been formed from a material such as polymethyl methacrylate (PMMA). However, the heat generated inside devices such as personal computers, mobile phones, and PDAs tends to increase, and the thermoplastic resin used has high heat resistance in order to cope with the lighter, thinner and smaller devices, and Resins having high mechanical strength are demanded, and PMMA is being replaced with polycarbonate resins.

  Polycarbonate resin is superior in mechanical properties, thermal properties, and electrical properties to PMMA, but slightly inferior in light transmittance. Therefore, in the case of the planar light source device using the polycarbonate resin light guide plate, there is a problem that the luminance is lowered as compared with PMMA.

  Conventionally, several methods for increasing the luminance of a light guide plate made of polycarbonate resin have been proposed.

  In Patent Document 2, a method of using a fluorescent whitening agent and a bead-shaped cross-linked acrylic resin in combination, improving luminance with a fluorescent whitening agent, and reducing unevenness in luminance with a bead-shaped cross-linked acrylic fine particle, Patent Document 3 discloses an acrylic resin. And a method for improving light transmittance and luminance by adding an alicyclic epoxy resin, and Patent Document 4 proposes a method for improving luminance by introducing copolyestercarbonate to improve the transfer of uneven patterns. Has been.

  However, in the method of Patent Document 2, although the brightness is partially improved, the light transmittance is lowered by the addition of a bead-shaped cross-linked acrylic resin or a fluorescent brightening agent, so that the brightness of a portion far from the light source of the light guide plate is lowered. However, there is a problem that uniform brightness cannot be obtained. In the method of Patent Document 3, the hue is improved by the addition of the acrylic resin, but since it becomes cloudy, the light transmittance and the luminance cannot be increased, and the transmittance is improved by adding the alicyclic epoxy resin. Although there is a possibility, there was a problem that the effect of improving the hue was not recognized. In the case of the method of Patent Document 4, although an improvement effect of fluidity and transferability can be expected, there is a drawback that heat resistance is lowered.

JP-A-10-55712 Japanese Patent Laid-Open No. 9-20860 JP-A-11-158364 JP 2001-215336 A

  The present invention does not impair the original properties of polycarbonate resin, that is, heat resistance, mechanical strength, etc., and further, has no hue and light transmittance reduction, and has good hue and brightness, and molding the same. Optical molded products such as a light guide plate, a surface light emitter material, and a name plate are provided.

  As a result of intensive studies to solve such problems, the present inventors have found that the polycarbonate resin contains a polystyrene resin and a specific antioxidant, so that there is no decrease in white turbidity or light transmittance, hue and brightness. The present invention was completed by finding that an optical molded article such as an excellent light guide plate can be obtained.

  That is, the present invention relates to 100 parts by weight of a resin component consisting of 97 to 99.95% by weight of a polycarbonate resin (A) and 0.05 to 3% by weight of a polystyrene resin (B) having a weight average molecular weight of 1000 to 18000, The present invention relates to a polycarbonate resin composition comprising 0.02 to 2 parts by weight of an antioxidant (C) and / or a phenolic antioxidant (D), and an optical molded article such as a light guide plate comprising the polycarbonate resin composition.

  Since the polycarbonate resin composition of the present invention is excellent in luminance, light transmittance, mechanical properties, heat resistance and hue stability, the hue is also obtained in the molding of a thin (about 0.3 mm thick) light guide plate. It does not change or the resin itself deteriorates, and the industrial utility value is extremely high.

  The polycarbonate resin (A) used in the present invention is obtained by 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) is usually 10,000 to 100,000, preferably 12,000 to 25,000, and more preferably 12,000 to 18,000. In producing such a polycarbonate resin, a molecular weight regulator, a catalyst and the like can be used as necessary.

  The weight average molecular weight of the polystyrene resin (B) used in the present invention is 1000 to 18000. When the weight average molecular weight of the polystyrene resin (B) is less than 1000, the light transmittance is inferior. When the weight average molecular weight exceeds 18000, the light transmittance and the haze ratio are inferior. More preferably, it is 1500-10000, More preferably, it is the range of 2000-4000.

  The composition ratio of the polystyrene resin (B) is 0.05 to 3% by weight, preferably 0.1 to 1% by weight, based on the resin component consisting of (A) and (B). When the composition ratio of the polystyrene resin (B) is less than 0.05% by weight, the light transmittance and the luminance cannot be improved. On the other hand, if the composition ratio exceeds 3% by weight, the light transmittance decreases and the haze increases, which is not preferable.

  Commercially available polystyrene resin (B) includes JONCRYL ADF-1300 manufactured by BASF.

Examples of the phosphorus-based antioxidant (C) and / or the phenol-based antioxidant (D) used in the present invention include the following compounds.
As phosphorus antioxidant (C), what consists of 1 type or more among the compounds represented by the following general formula 1, 2, and 3 is mentioned.
General formula 1

（一般式１において、Ｒ１〜４は炭素数１〜２０のアルキル基、またはアルキル基で
置換されてもよいアリール基を示す。）
一般式２

(In General Formula 1, R1-4 represent an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group.)
General formula 2

（一般式２において、Ｒ５、Ｒ６は炭素数１〜２０のアルキル基、またはアルキル基で置換されてもよいアリール基を、ａ、ｂは整数０〜３を示す。）
一般式３

(In General Formula 2, R5 and R6 represent an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and a and b represent integers 0 to 3.)
General formula 3

（一般式３において、Ｒ７は炭素数１〜２０のアルキル基、またはアルキル基で置換されてもよいアリール基を、ｃは０〜３の整数を示す。）

(In General Formula 3, R7 represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and c represents an integer of 0 to 3)

  The compound of general formula 1 is Sandstub P-EPQ manufactured by Clariant Japan, the compound of general formula 2 is Adekastab PEP-36 manufactured by Adeka, and the compound of general formula 3 is Sumitizer P- manufactured by Sumitomo Chemical. 168 is listed as commercially available.

  Moreover, as a phenolic antioxidant (D), the compound of the following general formula 4 is mentioned. Formula 4

（一般式４において、Ｒ８は炭素数１〜２０のアルキル基、またはアルキル基で置換されてもよいアリール基を示す。）

(In General Formula 4, R8 represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group.)

As the compound of the general formula 4, Irganox 1076 manufactured by Ciba Specialty Chemicals is commercially available.

  The compounding quantity of phosphorus antioxidant (C) and / or phenolic antioxidant (D) is 0.02-2 weight part per 100 weight part of resin components which consist of (A) and (B). If the blending amount is less than 0.02 parts by weight, the thermal stability is poor, which is not preferable. On the other hand, when the amount exceeds 2 parts by weight, the light transmittance is lowered and the haze value is raised, which is not preferable. The amount is preferably 0.04 to 1 part by weight, more preferably 0.05 to 0.2 part by weight. In this range, the light transmittance does not decrease, and excellent thermal stability is exhibited.

  In addition, various heat stabilizers, antioxidants, colorants, mold release agents, softeners, antistatic agents, and other additives, impact modifiers, and other polymers are added as long as the effects of the present invention are not impaired. You may mix | blend.

  There are no particular limitations on the method of mixing the various components of the polycarbonate resin composition of the present invention, and examples thereof include mixing with a known mixer such as a tumbler or ribbon blender or melt kneading with an extruder.

  There is no restriction | limiting in particular in the method to shape | mold the polycarbonate resin composition of this invention, A well-known injection molding method, a compression molding method, etc. can be used.

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

Based on the ingredients and amounts shown in Tables 1 to 4, various ingredients are mixed using a tumbler and melt kneaded at a cylinder temperature of 220 ° C. using a 40 mm diameter single screw extruder (manufactured by Tanabe Plastics). Various pellets were obtained.
The compounding components used are as follows.
1. Polycarbonate resin:
Polycarbonate resin synthesized from bisphenol A and carbonyl chloride SD1080 (viscosity average molecular weight: 15000) manufactured by Sumitomo Dow
(Hereinafter abbreviated as “PC1”)
Polycarbonate resin synthesized from bisphenol A and carbonyl chloride SD2000W (viscosity average molecular weight: 13000) manufactured by Sumitomo Dow
(Hereinafter abbreviated as “PC2”)

2. Polystyrene resin:
JONCRYL ADF-1300 made by BASF
(Weight average molecular weight: 2800, hereinafter abbreviated as “PS1”)
Polystyrene (weight average molecular weight: 800) manufactured by Aldrich
(Hereafter abbreviated as “PS2”.)
Polystyrene (weight average molecular weight: 4000) manufactured by Aldrich
(Hereinafter abbreviated as “PS3”)
Polystyrene (weight average molecular weight: 13000) manufactured by Aldrich
(Hereinafter abbreviated as “PS4”)
Polystyrene (weight average molecular weight: 20000) manufactured by Aldrich
(Hereinafter abbreviated as “PS5”)
Polystyrene (weight average molecular weight: 23000) manufactured by Aldrich
(Hereafter abbreviated as “PS6”.)
Polystyrene (weight average molecular weight: 35000) manufactured by Aldrich
(Hereinafter abbreviated as “PS7”)

3. Phosphorous antioxidants:
P-EPQ made by Clariant Japan
(Hereinafter abbreviated as “P-based AO1”)
Adeka Corporation Adeka Stub PEP-36
(Hereinafter abbreviated as “P-based AO2”.)
P-168 manufactured by Sumitomo Chemical Co., Ltd.
(Hereinafter abbreviated as “P-based AO3”)
4). Phenolic antioxidants:
Irganox 1076 manufactured by Ciba Specialty Chemicals
(Hereinafter abbreviated as “Ph-based AO”)

(Method of making test piece for measuring chromaticity, light transmittance and haze value)
The various pellets obtained were dried at 120 ° C. for 4 hours, and then measured for chromaticity, transmittance and haze value at 280 ° C. and injection pressure 1200 Kg / cm 2 using an injection molding machine (J-100SAII manufactured by Nippon Steel). A test piece (90 × 50 × 2 mm) was prepared.

(Chromaticity evaluation method)
The chromaticity was measured using a spectrophotometer CMS35-SP manufactured by Murakami Color Research Laboratory with a D65 light source and a viewing angle of 10 °. When the chromaticity measurement was performed at n = 10, the difference between the maximum value and the minimum value of x and y was 0.0005 or less. The results are shown in Tables 1 to 4.

(Evaluation method of light transmittance and haze value)
The light transmittance and haze value were measured using a haze meter HM-150 manufactured by Murakami Color Research Laboratory. The total light transmittance Tt was 90.4% or more and the haze value H was 0.7% or less. The results are shown in Tables 1 to 4. Note that the haze value is defined by the following equation by the total light transmittance Tt and the diffuse transmittance Td.
Haze value H (%) = (diffuse transmittance Td / total light transmittance Tt) × 100

判定： 合格（○）、不合格（×）

Judgment: Pass (○), Fail (×)

判定： 合格（○）、不合格（×）

Judgment: Pass (○), Fail (×)

判定： 合格（○）、不合格（×）

Judgment: Pass (○), Fail (×)

  As shown in Examples 1 to 10, the polycarbonate resin composition having the requirements of the present invention exhibited high light transmittance and luminance, excellent hue stability and low haze value.

In Comparative Example 1, the amount of PS1 was less than the specified amount, and the light transmittance was inferior.
In Comparative Example 2, the amount of PS1 was greater than the specified amount, and the light transmittance and haze value were inferior.
Comparative Example 3 was a case where the blending amount of the phosphorus antioxidant was less than specified, and the hue stability was inferior.
The comparative example 4 was a case where the compounding quantity of phosphorus antioxidant was more than prescription | regulation, and the light transmittance and the haze value were inferior.
The comparative example 5 was a case where the compounding quantity of a phenolic antioxidant was less than prescription | regulation, and hue stability was inferior.

  As shown in Examples 11 and 12, the polycarbonate resin composition having the requirements of the present invention exhibited high light transmittance and luminance, excellent hue stability and low haze value.

Comparative Example 6 was a case where PS2 having a weight average molecular weight of 800 was used, and the light transmittance was inferior.
In Comparative Example 7, PS5 having a weight average molecular weight of 20000 was used, and the light transmittance was inferior.
In Comparative Example 8, PS6 having a weight average molecular weight of 23000 was used, and the light transmittance and haze value were inferior.
In Comparative Example 9, when PS7 having a weight average molecular weight of 35000 was used, the light transmittance and haze value were inferior.

Claims (10)

  Polycarbonate resin (A) 97 to 99.95% by weight and polystyrene resin (B) 0.05 to 3% by weight of polystyrene resin (B) having a weight average molecular weight of 1000 to 18000, 100 parts by weight of phosphorus antioxidant (C) A polycarbonate resin composition comprising 0.02 to 2 parts by weight of a phenolic antioxidant (D). 2. The polycarbonate resin composition according to claim 1, wherein the polycarbonate resin (A) has a viscosity average molecular weight of 12,000 to 18,000.   2. The polycarbonate resin composition according to claim 1, wherein the polystyrene resin (B) has a weight average molecular weight of 1500 to 10,000.   The polycarbonate resin composition according to claim 1, wherein the polystyrene resin (B) has a weight average molecular weight of 2000 to 4000.   The composition ratio of the said polystyrene resin (B) is 0.1 to 2 weight% based on the said resin component, The polycarbonate resin composition as described in any one of Claims 1-4 characterized by the above-mentioned.   The amount of the phosphorus-based antioxidant (C) and / or the phenol-based antioxidant (D) is 0.05 to 0.2 parts by weight per 100 parts by weight of the resin component. 2. The polycarbonate resin composition according to 1. The polycarbonate resin composition according to claim 1, wherein the phosphorus-based antioxidant (C) is one or more compounds selected from compounds represented by the following general formulas 1, 2, and 3.
General formula 1

(In General Formula 1, R1-4 represent an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group.)
General formula 2

(In General Formula 2, R5 and R6 represent an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and a and b represent integers 0 to 3.)
General formula 3

(In General Formula 3, R7 represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and c represents an integer of 0 to 3) The polycarbonate resin composition according to claim 1, wherein the phenolic antioxidant (D) is a compound represented by the following general formula 4.
Formula 4

(In General Formula 4, R8 represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group.)   The molded article for optics formed by shape | molding the polycarbonate resin composition of any one of Claims 1-8.   The light-guide plate formed by shape | molding the polycarbonate resin composition of any one of Claims 1-8.