JP2010150470A - Antistatic polycarbonate resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic polycarbonate resin composition preventing reduction of thermal stability, a molecular weight and impact-resistance of a polycarbonate resin when a diglycerine fatty acid ester is used as an antistatic agent and having excellent transparency. <P>SOLUTION: The antistatic polycarbonate resin composition is characterized in that it comprises 100 pts.wt. of the polycarbonate resin (A), 0.1-5 pts.wt. of the diglycerine fatty acid ester (B), 0.0001-0.01 pt.wt. of an acidic substance (C) and 0.005-1 pt.wt. of a phosphorous antioxidant (D), and a molded article comprises the same. The antistatic polycarbonate resin composition is excellent in not only an antistatic property but also transparency, appearance and impact-resistance, and is preferably used for use in which it is transparent and deposition of dusts is abhorred, for example a peripheral member of a light source and a molded article in which a content can be confirmed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an antistatic polycarbonate resin composition excellent in thermal stability, impact resistance and transparency. More specifically, the present invention relates to an antistatic polycarbonate resin composition that prevents a decrease in molecular weight due to decomposition of a polycarbonate resin by an antistatic agent, improves impact resistance, and has excellent transparency.

Polycarbonate resins are excellent in impact resistance, heat resistance, and transparency, and are widely used in fields such as electrical / electronic, optical, building materials, medical, food, and vehicles. However, products obtained from polycarbonate resin are easily charged with static electricity, and there are problems associated with static electricity, such as adhesion of dust to packaging materials and molded products, electric shock during molding and use, and malfunction of OA machines. Conventionally, various formulations of antistatic agents have been studied.
Further, office equipment exterior parts such as optical disk cartridges are also required to have transparency so that the inside can be fully visually recognized simultaneously with the antistatic performance.

  In order to impart antistatic performance to the polycarbonate resin, a fatty acid monoglyceride is blended as an antistatic agent. (Patent Document 1) However, this composition cannot satisfy all of the antistatic performance, transparency and thermal stability.

  In addition, a diglycerin fatty acid ester and an antioxidant are blended in a polycarbonate resin. (Patent Document 2) Although this composition improves antistatic performance and transparency to some extent, there is a problem that it is inferior in thermal stability. In particular, since heat is applied in the melt-kneading process when the pellets of this composition are obtained and the molding process of the obtained pellets, a reaction occurs between the diglycerin fatty acid ester and the polycarbonate resin. There is a problem that the decomposition is promoted, the molecular weight is lowered, and the impact resistance inherent to the polycarbonate resin is remarkably lowered. Patent Document 2 discloses an example of a polycarbonate resin having a relatively high molecular weight of 25,000 in average molecular weight, but the polycarbonate resin generally used for injection molding has a lower molecular weight (viscosity average molecular weight of 17,000 to 21000). Therefore, Patent Document 2 has a fundamental problem in practical use in terms of the reduction in impact resistance.

Japanese Patent Publication No.55-4141 Japanese Patent Laid-Open No. 02-196852

  The present invention prevents the deterioration of the thermal stability, molecular weight and impact resistance of a polycarbonate resin when the above-mentioned diglycerin fatty acid ester is used as an antistatic agent, and has an excellent antistatic polycarbonate. It aims at providing a resin composition.

  As a result of diligent research in view of the above-mentioned problems, the present inventor has formulated a polycarbonate resin with a combination of diglycerin fatty acid ester and an acidic substance, thereby improving the thermal stability, molecular weight, and impact resistance of the polycarbonate resin. The inventors have found that an antistatic polycarbonate resin composition having excellent transparency can be obtained by adding a phosphorus-based antioxidant, and the present invention has been completed.

  That is, the present invention comprises 100 parts by weight of a polycarbonate resin (A), 0.1 to 5 parts by weight of a diglycerin fatty acid ester (B), 0.0001 to 0.01 parts by weight of an acidic substance (C) and a phosphorus-based antioxidant. (D) The present invention relates to an antistatic polycarbonate resin composition characterized by comprising 0.005 to 1 part by weight and a molded product comprising the same.

  The antistatic polycarbonate resin composition of the present invention is excellent not only in antistatic properties but also in transparency and appearance and impact resistance, and is transparent and used in applications where dust adhesion is avoided, such as confirmation of peripheral members and contents of light sources It is suitably used for molded products that can be used.

  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 an aromatic 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 15,000 to 35,000, and more preferably 17,000 to 21,000. In producing such a polycarbonate resin, a molecular weight regulator, a catalyst and the like can be used as necessary.

  The diglycerin fatty acid ester (B) used in the present invention can be obtained by esterification of diglycerin obtained by polymerizing glycerin and a fatty acid.

  As the diglycerin fatty acid ester (B), an ester compound of a fatty acid having 10 to 18 carbon atoms and diglycerin is preferably used. If the carbon number is less than 10, the sustainability of the antistatic performance may be inferior, and if the carbon number exceeds 18, the antistatic property may be inferior.

Examples of the fatty acid having 10 to 18 carbon atoms include capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid.

Specific examples of the diglycerin fatty acid ester (B) include diglycerin monolaurate, diglycerin monomyristate, and diglycerin monostearate. Diglycerin monolaurate is preferably used.

  The compounding amount of the diglycerin fatty acid ester (B) of the present invention is 0.1 to 5 parts by weight per 100 parts by weight of the polycarbonate resin (A). If the blending amount is less than 0.1 parts by weight, the antistatic property is inferior, and if it exceeds 5 parts by weight, the transparency and the appearance are deteriorated. More preferably, it is the range of 0.5-3 weight part.

  Examples of the acidic substance (C) used in the present invention include compounds such as phosphoric acid and boric acid. In particular, phosphoric acid which is a nonvolatile weak acid is preferably used.

  The compounding amount of the acidic substance (C) is 0.0001 to 0.01 part by weight per 100 parts by weight of the polycarbonate resin (A). If the blending amount is less than 0.0001 part by weight or more than 0.01 part by weight, the thermal stability and impact resistance are inferior. More preferably, it is the range of 0.001-0.005 weight part.

The phosphorus antioxidant (D) used in the present invention is composed of at least one of the compounds represented by the following general formulas (1) to (3) and a cyclic phosphite antioxidant. Is mentioned. In particular, a cyclic phosphite antioxidant is preferably used.
General formula (1)

In General formula (1), R1-4 shows a C1-C20 alkyl group or an aryl group. R1 to R4 may be the same or different.
Preferable examples of the substituent represented by R1 to R4 include 2,4-di-tert-butylphenyl.

General formula (2)

In General formula (2), R5 and R6 represent a C1-C20 alkyl group or an aryl group. R5 and R6 may be the same or different.
Preferable examples of the substituents represented by R5 and R6 include 2,4-di-tert-butylphenyl.

General formula (3)

In General formula (3), Ar shows the aryl group which may be substituted by a C1-C20 alkyl group. Ar may be the same or different.
Preferable examples of the substituent represented by Ar include 2,4-di-tert-butylphenyl.

  Examples of the cyclic phosphite antioxidant include those produced by reacting phenols or bisphenols, phosphorus trihalide and an amine compound. As a reaction method, a two-step reaction method is generally employed in which phenols or bisphenols and phosphorus trihalide are first reacted to form an intermediate, and then an amine compound is reacted. The reaction is usually performed in an organic solvent in an environment of 0 to 200 ° C. Of the cyclic phosphite antioxidants, 2,4,8,10-tetra-t-butyl-6- [3- (3-methyl-4hydroxy-5-t-butylphenyl) propoxy] dibenzo is particularly useful. [D, f] [1,3,2] dioxaphosphine is suitable, and is available as a commercial product, and Sumitomo Chemical Co., Ltd. Sumilizer GP can be mentioned.

  As a compounding quantity of phosphorus antioxidant (D), it is 0.005-1 weight part per 100 weight part of polycarbonate resin (A). If the blending amount is less than 0.005 parts by weight, the thermal stability is poor, which is not preferable. On the other hand, when the amount exceeds 1 part by weight, the light transmittance decreases, which is not preferable. This amount is preferably in the range of 0.01 to 0.5 parts by weight, more preferably 0.02 to 1 parts by weight.

  The antistatic polycarbonate resin composition of the present invention can be used in combination with other antistatic agents as long as the effects of the present invention are not impaired. As other antistatic agents that can be used in combination, widely known ones can be used, and examples thereof include alkylsulfonates, alkylbenzenesulfonates, ammonium salts, and other phosphonium salts. It is not limited to.

  The mixing method and mixing order of the polycarbonate resin (A), diglycerin fatty acid ester (B), acidic substance (C) and phosphorus antioxidant (D) are not particularly limited, and known mixers such as tumblers, It can be carried out by mixing with a ribbon blender, a high-speed mixer or the like and then melt-kneading with a single screw or twin screw extruder.

  Furthermore, a known additive such as a heat stabilizer, a release agent, an ultraviolet absorber, a flame retardant, and a dye / pigment may be blended as necessary within a range not impairing the effects of the present invention. .

  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 unless otherwise specified.

  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 250 ° C. using a twin screw extruder (TEX-30α manufactured by Nippon Steel). Various pellets were obtained.

The compounding components used are as follows.
1. Polycarbonate resin:
Sumitomo Dow Caliber 200-20
(Viscosity average molecular weight: 19000, hereinafter abbreviated as PC)
2. Diglycerin fatty acid ester:
Diglycerin monolaurate (Poem DL-100 manufactured by Riken Vitamin Co., hereinafter abbreviated as antistatic agent)
3. Acidic substances:
Phosphoric acid (Nacalai Tesque, hereinafter abbreviated as acidic substance)
4). Phosphorous antioxidants:
Cyclic phosphite antioxidant (Sumitomo Chemical Co., Ltd., Sumitizer GP, hereinafter abbreviated as AO)
2,4,8,10-tetra-tert-butyl-6- [3- (3-methyl-4hydroxy-5-tert-butylphenyl) propoxy] dibenzo [d, f] [1,3,2]
Dioxaphosphepine

  Using the obtained pellets, various test pieces were prepared using an injection molding machine (J100SAII manufactured by Nippon Steel Works) at a set temperature of the cylinder of 300 ° C. and subjected to each test.

The test method is as follows.
Melt volume rate (MVR):
The measurement was performed at 280 ° C. according to ISO 1133. It was passed 20cm ^3/10 minutes or less.

・ Surface resistivity:
A 70 × 40 × 3 mm flat plate was prepared by injection molding and measured under the following conditions.
After the plate test piece was conditioned for 24 hours under the conditions of 23 ° C. and 55% relative humidity, a high resistivity meter (Hirester UP MCP-HT450 manufactured by Mitsubishi Chemical Corporation) was used, and the measurement voltage was 1000 V and the sampling time was 30 seconds. The surface resistivity was measured under the conditions.
A surface resistivity of less than 1 × 10 ¹⁴ Ω / sq was accepted.

・ Charpy impact strength:
The notched Charpy impact strength at 23 ° C. was measured according to ISO 179-2.
10 kJ / m ² or more was accepted.

・ Total light transmittance:
Measured according to ASTM D1003. More than 87% was accepted.

ΔYI:
A 70 × 40 × 3 mm flat plate was formed by injection molding, then retained in a cylinder at a set temperature of 340 ° C. for 30 minutes, and further molded. The yellowness index (YI) of the molded product before residence and the molded product after residence was measured in accordance with ASTM D-1925. The difference between YI before retention and YI after residence was ΔYI, and 2 or less was accepted.

  The test results are shown in Tables 1 and 2.

  As shown in Examples 1 to 6, the polycarbonate resin composition having the requirements of the present invention satisfies all required performances including the surface specific resistance value.

On the other hand, in the case where the requirements of the present invention were not satisfied, each case had some drawbacks.
The comparative example 1 was inferior to MVR in the case where there are few compounding quantities of an acidic substance.
Comparative Example 2 was a case where the compounding amount of the acidic substance was large and was inferior to ΔYI.
In Comparative Example 3, the amount of AO was small, and the ΔYI value did not satisfy the required level.
In Comparative Example 4, the amount of AO blended was large, and the light transmittance and ΔYI value did not satisfy the required levels.
In Comparative Example 5, the amount of the antistatic agent was small, and the surface resistivity did not satisfy the required level.
In Comparative Example 6, the amount of the antistatic agent was large, and the MVR, Charpy impact strength, ΔYI value, and light transmittance did not satisfy the required levels.

Claims (10)

  100 parts by weight of polycarbonate resin (A), 0.1 to 5 parts by weight of diglycerin fatty acid ester (B), 0.0001 to 0.01 parts by weight of acidic substance (C) and 0.005 of phosphorus antioxidant (D) An antistatic polycarbonate resin composition comprising ˜1 part by weight.   2. The antistatic polycarbonate resin composition according to claim 1, wherein the diglycerin fatty acid ester (B) is an ester compound of a fatty acid having 10 to 18 carbon atoms and diglycerin.   2. The antistatic polycarbonate resin composition according to claim 1, wherein the diglycerin fatty acid ester (B) is diglycerin monolaurate.   2. The antistatic polycarbonate resin composition according to claim 1, wherein the amount of the diglycerin fatty acid ester (B) is 0.5 to 3 parts by weight per 100 parts by weight of the polycarbonate resin (A).   The antistatic polycarbonate resin composition according to claim 1, wherein the acidic substance (C) is one or more selected from phosphoric acid and boric acid.   The antistatic polycarbonate resin composition according to claim 1, wherein the amount of the acidic substance (C) is 0.001 to 0.005 parts by weight per 100 parts by weight of the polycarbonate resin (A).   The antistatic polycarbonate resin composition according to claim 1, wherein the phosphorus-based antioxidant (D) is a cyclic phosphite-based antioxidant.   Cyclic phosphite antioxidants include 2,4,8,10-tetra-t-butyl-6- [3- (3-methyl-4hydroxy-5-t-butylphenyl) propoxy] dibenzo [d , F] [1, 3, 2] dioxaphosphine, the antistatic polycarbonate resin composition according to claim 7.   2. The antistatic polycarbonate resin composition according to claim 1, wherein the amount of the phosphorus antioxidant (D) is 0.01 to 0.5 parts by weight per 100 parts by weight of the polycarbonate resin (A). .   A molded product formed by molding the antistatic polycarbonate resin composition according to any one of claims 1 to 9.