JP5058147B2 - Antistatic polycarbonate resin composition with low molecular weight reduction and method for producing the same - Google Patents

Description

  The present invention relates to an antistatic polycarbonate resin composition excellent in thermal stability and impact resistance and a method for producing the same. More specifically, the present invention relates to an antistatic polycarbonate resin composition and a method for producing the same, in which a decrease in molecular weight due to decomposition of the polycarbonate resin by an antistatic agent is prevented, and a decrease in impact resistance is greatly improved.

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 for obtaining pellets of this composition 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 25000 average molecular weight, but the polycarbonate resin generally used for injection molding has a lower molecular weight (viscosity average molecular weight of 17000 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 is a polycarbonate resin composition that prevents deterioration of the thermal stability, molecular weight, and impact resistance of a polycarbonate resin when the above-described diglycerin fatty acid ester is used as an antistatic agent, and has excellent antistatic performance. It is an object to provide a product and a method for manufacturing the product.

  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 a 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 the reduction can be remarkably prevented and have completed the present invention.

That is, the first aspect of the present invention is a polycarbonate resin composition (C) comprising a polycarbonate resin (A) and a diglycerin fatty acid ester (B) as essential components,
(1) The amount of diglycerin fatty acid ester (B) is polycarbonate resin (A)
MW0 to MW1 when the viscosity average molecular weight of the polycarbonate resin (A) is MW0 and the viscosity molecular weight of the polycarbonate resin composition (C) is MW1 per 100 parts by weight. The present invention relates to an antistatic polycarbonate resin composition having a small decrease in molecular weight, characterized by having a value obtained by subtracting ≦ 600.

  In addition, in the second aspect of the present invention, in the production of the polycarbonate resin composition (C) comprising the polycarbonate resin (A) and the diglycerin fatty acid ester (B) as essential components, the acidic substance (D) 0.0001-0 The present invention relates to a method for producing an antistatic polycarbonate resin composition having a small decrease in molecular weight, characterized by adding .01 part by weight (per 100 parts by weight of polycarbonate resin (A)) and melt-kneading.

  The antistatic polycarbonate resin composition of the present invention is excellent not only in antistatic properties but also in impact resistance, and is transparent and used in applications where dust adhesion is avoided, such as a light source peripheral member and a molded product in which the contents can be confirmed. Preferably 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 (D) used in the present invention include compounds such as phosphoric acid and boric acid, and phosphoric acid which is a nonvolatile weak acid is particularly preferably used.

  The compounding amount of the acidic substance (D) 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 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.

  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. .

As a method for producing the antistatic polycarbonate resin composition of the present invention, an acidic substance (D) is added to a composition comprising polycarbonate resin (A) and diglycerin fatty acid ester (B) as essential components, and melt kneading. The method of doing is mentioned. In particular,
(1) To one or two selected from polycarbonate resin (A) and diglycerin fatty acid ester (B), an acidic substance (D) is added in advance and kneaded.
(2) To the polycarbonate resin (A), the acidic substance (D) is added in advance and melt kneaded, and then the diglycerin fatty acid ester (B) is added to the melt kneaded product and melt kneaded.
(3) The acidic substance (D) is added to the diglycerin fatty acid ester (B) in advance to create a mixture, and the mixture is added to the melt of the polycarbonate resin (A) and melt-kneaded.
Methods and the like. Among these, the method (2) is preferably used from the viewpoint of controlling the addition amount. By employ | adopting the said manufacturing method, the fall of the molecular weight of the obtained antistatic polycarbonate resin composition is suppressed, and a fall of impact resistance can be prevented.

  There are no particular limitations on the mixing method of two or more selected from polycarbonate resin (A), diglycerin fatty acid ester (B) and acidic substance (D), and known mixers such as tumblers, ribbon blenders, They can be mixed by a high-speed mixer or the like and then melt-kneaded by a single screw or twin screw extruder.

  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.

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)

(Examples 1-3 and Comparative Examples 1-4)
Based on the blending components and blending amounts shown in Tables 1 and 2, the various blending components were mixed together using a tumbler, and the cylinder temperature was 250 ° C. using a twin-screw extruder (TEX-30α manufactured by Nippon Steel). Various types of pellets were obtained by melt-kneading.

  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.
・ 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.

・ Molecular weight reduction:
A polycarbonate resin (composition) is dissolved in methylene chloride to prepare a solution having a resin (composition) concentration of 0.38% by weight. About the obtained solution, the viscosity was measured under the temperature of 20 degreeC using the Canon Fensuke viscosity tube. The viscosity average molecular weight was calculated according to the following formula.
[η] = 1.23 × 10 ⁻⁴ M ^0.83
[η]: Intrinsic viscosity M: Viscosity average molecular weight When the viscosity average molecular weight of the polycarbonate resin (A) is MW0 and the viscosity average molecular weight of the polycarbonate resin composition (C) is MW1, a value obtained by subtracting MW1 from MW0 (hereinafter referred to as ΔMW) Abbreviated as 600) or less.

・ Yellowness Index (YI)
A 70 × 40 × 3 mm flat plate was produced by injection molding, using a high-speed color analyzer CMS-35SP manufactured by Murakami Color Research Laboratory Co., Ltd., and conforming to ASTM D-1925.
Was measured. 2 or less was accepted.

  The test results are shown in Tables 1 and 2.

  As shown in Examples 1 to 3, the polycarbonate resin composition having the requirements of the present invention satisfies all the 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.
In Comparative Example 1, the amount of the antistatic agent was small, and the surface resistivity did not satisfy the required level.
In Comparative Example 2, the amount of the antistatic agent was large, and ΔMW, Charpy impact strength, and YI did not satisfy the required levels.
In Comparative Example 3, no acidic substance was added, and ΔMW and Charpy impact strength did not satisfy the required levels.
In Comparative Example 4, the amount of acidic substance was large, and YI did not satisfy the required level.

Example 4
Based on the same blending components and blending amounts as those in Example 1, the same operations and evaluations as in Example 1 were performed except that the blending component mixing method and the melt kneading method were changed as follows.
100 parts of PC and 0.001 part of acidic substance are mixed using a tumbler, melt-kneaded at a cylinder temperature of 250 ° C. using a twin screw extruder (TEX-30α manufactured by Nippon Steel Works, barrel number 12), and then 0.5 part of the antistatic agent was added from the zone of the barrel 9 to the melt-kneaded product using a liquid pump, and melt-kneaded to obtain pellets.
The results are shown in Table 3.

(Example 5)
Based on the same blending components and blending amounts as in Example 1, the same operations and evaluations as in Example 1 were performed except that the blending method and the melt-kneading method were changed as follows.
100 parts of PC was melt-kneaded at a cylinder temperature of 250 ° C. using a twin screw extruder (TEX-30α manufactured by Nippon Steel Works, barrel number 12), and 0.5 parts of antistatic agent and acidic substance 0 were mixed in advance. A mixture of 0.001 part was added from the zone of the barrel 9 to the melt-kneaded product using a liquid pump, and melt-kneaded to obtain pellets.
The results are shown in Table 3.

(Comparative Example 5)
All operations and evaluations were the same as in Example 4 except that no acidic substance was added.
The results are shown in Table 3.

  As shown in Examples 4 to 5, 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, Comparative Example 5 was a case where no acidic substance was added, and a decrease in molecular weight and a decrease in impact strength were observed.

Claims (10)

A polycarbonate resin composition (C) comprising a polycarbonate resin (A) and a diglycerin fatty acid ester (B) as essential components,
(1) The amount of diglycerin fatty acid ester (B) is polycarbonate resin (A)
When the viscosity average molecular weight of the polycarbonate resin (A) is MW0 and the viscosity average molecular weight of the polycarbonate resin composition (C) is MW1 per 100 parts by weight, from MW0 A value obtained by subtracting MW1 is 600 or less, and an antistatic polycarbonate resin composition having a small decrease in molecular weight.   2. The antistatic polycarbonate resin composition having a small molecular weight reduction 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 with little molecular weight reduction according to claim 1, wherein the diglycerin fatty acid ester (B) is diglycerin monolaurate.   2. The antistatic polycarbonate resin composition with little molecular weight reduction 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). object.   In the production of the polycarbonate resin composition (C) comprising the polycarbonate resin (A) and the diglycerin fatty acid ester (B) as essential components, 0.0001 to 0.01 part by weight of the acidic substance (D) (polycarbonate resin (A) 100 A method for producing an antistatic polycarbonate resin composition with low molecular weight reduction, characterized by adding (per part by weight) and melt-kneading.   The acidic substance (D) is added in advance to one or two kinds selected from the polycarbonate resin (A) and the diglycerin fatty acid ester (B) and melt-kneaded. A method for producing an antistatic polycarbonate resin composition with a small decrease in molecular weight.   The acidic substance (D) is previously added to the polycarbonate resin (A) and melt kneaded, and then the diglycerin fatty acid ester (B) is added to the melt kneaded product and melt kneaded. Item 6. A method for producing an antistatic polycarbonate resin composition according to Item 5, wherein the molecular weight reduction is small.   The acidic substance (D) is added to the diglycerin fatty acid ester (B) in advance to prepare a mixture, and the mixture is added to the melt of the polycarbonate resin (A) and melt kneaded. 5. A method for producing an antistatic polycarbonate resin composition having a small molecular weight decrease according to 5.   The antistatic polycarbonate resin composition with low molecular weight reduction according to any one of claims 5 to 8, wherein the acidic substance (D) is one or two selected from phosphoric acid and boric acid. Manufacturing method.   6. The antistatic polycarbonate resin with little molecular weight reduction according to claim 5, wherein the compounding amount of the acidic substance (D) is 0.001 to 0.005 parts by weight per 100 parts by weight of the polycarbonate resin (A). A method for producing the composition.