JP2012171995A - Polycarbonate resin composition and optical molded article obtained from the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin composition that has high light transmittance and luminance and excellent hue without diminishing heat resistance, mechanical strength, etc., and an optical molded article, such as a light guide plate, a surface emitter material, and a nameplate, obtained by molding the polycarbonate resin composition, and especially to provide the polycarbonate resin composition that is most suitable for light guide plate applications because of the high light transmittance and luminance possessed.SOLUTION: The polycarbonate resin composition comprises: 100 pts.wt. of a resin component comprising 97-99.95 wt.% of a polycarbonate resin (A) having a viscosity-average molecular weight of 10,000-19,000 and a ratio (Mw/Mn) of a weight-average molecular weight to a number-average molecular weight, both of which are measured by GPC and undergo polystyrene conversion, of 1.3-2.0; 0.05-3 wt.% of a polystyrene resin (B) having a weight-average molecular weight of 1,000-18,000; and 0.02-2 pts.wt. of an antioxidant (C) as essential components. The optical molded article is obtained from the polycarbonate resin composition.

Description

  The present invention relates to a polycarbonate resin composition having a high light transmittance and luminance without impairing heat resistance, mechanical strength and the like, and excellent in hue, and a light guide plate and a surface light emitter formed by molding the same. The present invention relates to optical molded products such as 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 luminance is partially improved, the light transmittance is reduced by the addition of a bead-shaped cross-linked acrylic resin or a fluorescent brightening agent. 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 relates to a polycarbonate resin composition having a high light transmittance and luminance without impairing heat resistance, mechanical strength and the like, and excellent in hue, and a light guide plate and a surface light emitter formed by molding the same. The present invention relates to optical molded products such as materials and nameplates. In particular, the present invention relates to a polycarbonate resin composition that is optimal for use as a light guide plate because it has high light transmittance and luminance.

  As a result of intensive studies to solve such problems, the present inventors have found that a polycarbonate resin having a specific molecular weight and molecular weight distribution contains a polystyrene resin and an antioxidant, so that an extremely high light transmittance and The present invention has been completed by finding that an optical molded product such as a light guide plate having brightness and good hue can be obtained.

That is, the present invention relates to a polycarbonate resin (A) having a viscosity average molecular weight of 10,000 to 19000 (97) to 99.95% by weight and a polystyrene resin (B) having a weight average molecular weight of 1000 to 18000 from 0.05 to 3% by weight. A polycarbonate resin composition comprising 100 parts by weight of a resin component and 0.02 to 2 parts by weight of an antioxidant (C) as essential components,
The polycarbonate resin (A) has a ratio (Mw / Mn) of weight average molecular weight and number average molecular weight in terms of polystyrene measured by gel permeation chromatography of 1.3 to 2.0.
The present invention relates to a polycarbonate resin composition characterized by the above, and an optical molded article such as a light guide plate comprising the same.

  Since the polycarbonate resin composition of the present invention is excellent in luminance, light transmission performance, mechanical properties, heat resistance and hue stability, the hue is also obtained in the molding process of a thin (about 0.3 mm thick) light guide plate. It does not change or the resin itself deteriorates, and has a high light transmittance and luminance, so that 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 dihydroxy diaryl compounds and phosgene are reacted or a transesterification method obtained by reacting a dihydroxy diaryl 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 polycarbonate resin (A) has a viscosity average molecular weight of 10,000 to 19000, and a ratio (Mw / Mn) of polystyrene-equivalent weight average molecular weight and number average molecular weight measured by gel permeation chromatography is 1.3 to 2. .0 is a requirement.

  The method for adjusting the viscosity average molecular weight of the polycarbonate resin is not particularly limited. For example, a polycarbonate resin having a desired molecular weight can be obtained by adjusting the amount of the molecular weight regulator used in the polymerization step.

The above viscosity average molecular weight is 0.5 wt% polycarbonate resin solution using methylene chloride as a solvent, and the specific viscosity (η _sp ) is measured at a temperature of 20 ° C. using a Cannon-Fenske type viscosity tube. [Η] was obtained and calculated from the following SCHNELL equation.
[Η] = 1.23 × 10 ⁻⁴ M ^0.83

  On the other hand, the method for adjusting the (Mw / Mn) ratio of the polycarbonate resin is not particularly limited. For example, the amount of the molecular weight regulator used in the polymerization process, the addition timing of the molecular weight regulator may be changed, A method of adjusting polymerization conditions such as time and reaction temperature, a method of supplying polycarbonate resin pellets and powder to a poor solvent such as acetone to extract and remove low molecular weight components in the polycarbonate resin, or polycarbonate is a good solvent Examples include a method of preparing a solution dissolved in methylene chloride or the like and supplying the solution to acetone or the like as a poor solvent to precipitate a polycarbonate resin from which low molecular weight components are reduced or removed.

Said (Mw / Mn) ratio was calculated | required from the weight average molecular weight (Mw) and number average molecular weight (Mn) of polystyrene conversion measured by the gel permeation chromatography. The measurement conditions are as follows.
Apparatus: HP1100 manufactured by HEWLETT PACKARD
Column: manufactured by Polymer Laboratories
PLGe1 5μ MIXED-C
Fluid phase: Tetrahydrofuran Detector: UV lamp VWD module 264nm
The measurement solution was adjusted to a 0.5 wt% polycarbonate resin solution using methylene chloride as a solvent and filtered through a 0.2 μm polytetrafluoroethylene filter.

When the viscosity average molecular weight of the polycarbonate resin (A) is less than 10,000, the mechanical strength is lowered, which is not preferable. On the other hand, if it exceeds 19000, the molding processability is inferior, so that it is difficult to mold a thin-walled / large-sized light guide plate and the transferability required for the optical pattern is not only inferior but also the luminance is lowered, which is not preferable. Preferably, it is the range of 10,000-17000.
Moreover, when the ratio (Mw / Mn) of the weight average molecular weight and the number average molecular weight in terms of polystyrene measured by gel permeation chromatography of the polycarbonate resin (A) is less than 1.3, molding processability is insufficient. If it exceeds 2.0, the light transmittance and luminance are lowered, which is not preferable. More preferably, it is the range of 1.4-1.8.

  The weight average molecular weight of the polystyrene resin (B) used in the present invention is 1000 to 18000. Exceeding this range is not preferable because the light transmittance decreases. 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. Further, if the composition ratio exceeds 3% by weight, the light transmittance decreases, which is not preferable.

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

Examples of the antioxidant (C) used in the present invention include phosphorus antioxidants and phenolic antioxidants.
As phosphorus antioxidant, 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, 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 antioxidant (C) 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, if the amount exceeds 2 parts by weight, the light transmittance decreases, 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.

  Furthermore, an additive such as a colorant, a release agent, a softening material and an antistatic agent, an impact modifier, and other polymers may be blended within the range not impairing the effects of the present invention.

  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.

(Preparation of polycarbonate resin with low low molecular weight components)
A polycarbonate resin synthesized from bisphenol A and carbonyl chloride (Caliber SD 1080 (hereinafter abbreviated as “PC1”) manufactured by Sumitomo Dow Co., Ltd. was prepared as a raw material resin. The viscosity average molecular weight of PC1 was 15000, measured by gel permeation chromatography. The ratio (Mw / Mn) between the weight average molecular weight and the number average molecular weight in terms of polystyrene was 2.3.

Next, PC1 was introduced into methylene chloride so as to have a concentration of 60 g of PC1 per liter of methylene chloride, and dissolved at room temperature with stirring. The resulting methylene chloride solution of PC1 was transferred to a separatory funnel and dropped into acetone in the same volume as methylene chloride while stirring to reprecipitate the polycarbonate.
By the above operation, a powdery polycarbonate and an acetone solution in which low molecular weight components were extracted and dissolved were obtained.
In order to separate and collect the powdery polycarbonate, suction filtration was performed using a glass filter. Thereafter, the powdery polycarbonate laminated on the glass filter was washed with acetone three times.
The obtained powdery polycarbonate was transferred to a glass container and dried under reduced pressure at 80 ° C. for 18 hours using a vacuum dryer.
The polycarbonate resin after drying (hereinafter abbreviated as “PC2”) obtained by the above operation has a viscosity average molecular weight of 16,300, and the ratio of the weight average molecular weight in terms of polystyrene to the number average molecular weight measured by gel permeation chromatography. (Mw / Mn) was 1.6.

Example 1
P-EPQ manufactured by Clariant Japan Co., Ltd. using 99 parts of the obtained PC2 and 1 part of polystyrene resin having a weight average molecular weight of 2800 (JONCRYL ADF-1300 (hereinafter abbreviated as “PS1”) manufactured by BASF) and an antioxidant. (Hereinafter abbreviated as “AO1”) at a blending ratio of 0.1 part using a tumbler, and using a 40 mm diameter single screw extruder (manufactured by Tanabe Plastics) to a cylinder temperature of 220 ° C. And kneaded to obtain pellets of the polycarbonate resin composition.

  The following evaluation was performed using the obtained pellet. The results are shown in Table 1.

(How to make a test piece for total transmittance and luminance measurement)
The obtained pellets were dried at 120 ° C. for 4 hours, and then an JIS K7139 multipurpose test piece A type (length) at a molding temperature of 280 ° C. and a mold temperature of 100 ° C. using an injection molding machine (J-100SAII manufactured by Nippon Steel). 168 mm × thickness 4 mm). The end face was cut, and the cut end face was mirror-finished using a resin plate end face mirror machine PB-500 manufactured by Megaro Technica.

(Evaluation method of integrated transmittance)
The integrated transmittance is set to a Hitachi spectrophotometer U-4100 with a long optical path measurement accessory, using a 50 W halogen lamp as a light source, a mask before light source 5.6 mm × 2.8 mm, and a mask before sample 6.0 mm × 2 It was obtained by measuring the spectral transmittance every 1 nm in a state where 0.8 mm was used. The accumulated light transmittance in the wavelength range of 380 to 780 nm was determined to be 32,000 or more.

(Brightness evaluation method)
For evaluation of luminance, an LED lamp was brought into contact with the end surface of the above-mentioned multipurpose test piece, and the luminance was measured by installing a Topcon luminance meter BM-7 at a position of 418 mm from the LED lamp (168 mm test piece, 250 mm from the LED end surface). . As the light source, two of the three LED lamps of NTT N211is mobile phone were used. In order to prevent light passing through the multipurpose test piece from leaking to the outside, a test piece cover was prepared and installed using a light reflective polycarbonate SD polycarbonate LR8031V manufactured by Sumitomo Dow.
The luminance measured in a state where the LED was lit was 13200 cd / m 2 or more as a pass.

(Comparative Example 1)
Except for using PC1 instead of PC2, all operations were the same as in Example 1 to obtain polycarbonate resin composition pellets. Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 2)
In the adjustment of PC2, except that methyl alcohol was used instead of acetone, the same operation as the adjustment of PC2 was performed to prepare a polycarbonate resin after drying (hereinafter abbreviated as “PC3”).
The viscosity average molecular weight of PC3 was 15700, and the ratio (Mw / Mn) of polystyrene-equivalent weight average molecular weight and number average molecular weight measured by gel permeation chromatography was 2.1.
Using this, evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Examples 2-4, Comparative Examples 3-4)
Based on the blending components and blending amounts shown in Tables 1 and 2, various blending components were mixed using a tumbler and melt kneaded at a cylinder temperature of 220 ° C. using a 40 mm diameter single screw extruder (Tanabe Plastics). Various pellets were obtained.
The compounding components used are as follows.
Polystyrene resin:
Polystyrene (weight average molecular weight: 800) manufactured by Aldrich
(Hereafter abbreviated as “PS2”.)
Polystyrene (weight average molecular weight: 20000) manufactured by Aldrich
(Hereinafter abbreviated as “PS3”)
Phosphorous antioxidants:
Adeka Corporation Adeka Stub PEP-36
(Hereinafter abbreviated as “AO2”)
P-168 manufactured by Sumitomo Chemical Co., Ltd.
(Hereafter abbreviated as “AO3”.)
The results are shown in Tables 1 and 2.

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 4, when the requirements of the present invention were satisfied, the integrated light transmittance and luminance were excellent in the wavelength region of 380 to 780 nm.

  On the other hand, as shown in Comparative Examples 1 to 4, when the requirements of the present invention were not satisfied, the integrated light transmittance and luminance were inferior in the wavelength region of 380 to 780 nm.

Claims (4)

100 parts by weight of a resin component comprising 97 to 99.95% by weight of a polycarbonate resin (A) having a viscosity average molecular weight of 10,000 to 19000 and 0.05 to 3% by weight of a polystyrene resin (B) having a weight average molecular weight of 1000 to 18000 And a polycarbonate resin composition comprising 0.02 to 2 parts by weight of an antioxidant (C) as an essential component,
The polycarbonate resin (A) has a ratio (Mw / Mn) of weight average molecular weight and number average molecular weight in terms of polystyrene measured by gel permeation chromatography of 1.3 to 2.0.
A polycarbonate resin composition characterized by that.   The polycarbonate resin composition according to claim 1, wherein the polystyrene resin (B) has a weight average molecular weight of 2000 to 4000.   An optical molded article obtained by molding the polycarbonate resin composition according to claim 1.   A light guide plate formed by molding the polycarbonate resin composition according to claim 1.