Antistatic polycarbonate resin composition pellets and method for producing the same

Abstract

The present invention relates to an antistatic polycarbonate resin composition pellet and a method for producing the same, which can form molded products having excellent antistatic properties and appearance, and containing extremely low levels of impurity ions such as fluoride ions, sulfate ions, and calcium ions. [Solution] A polycarbonate resin composition pellet comprising 100 parts by weight of a resin component consisting of an aromatic polycarbonate resin (A) and an acrylonitrile-butadiene-styrene copolymer (B), 5 to 20 parts by weight of a polyamide-polyether block copolymer (C), and 0.1 to 2.0 parts by weight of a phosphate ester compound (D), wherein the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09, wherein the fluoride ion concentration eluted from 30 g of pellets in 30 mL of 50°C hot water for 3 hours is less than 1 μg / L, the sulfate ion concentration is less than 30 μg / L, and the calcium ion concentration is less than 30 μg / L.

Description

Technical Field

[0001] The present invention relates to an antistatic polycarbonate resin composition pellet and a method for producing the same.

Background Art

[0002] Polycarbonate resin is a thermoplastic resin excellent in transparency, impact resistance, heat resistance, thermal stability, etc., and is widely used in fields such as electrics, electronics, ITE (information technology equipment), machinery, and automobiles. Among them, in recent years, because of its excellent heat resistance, thermal stability, impact resistance, etc., its use as a member for containers such as electronic-related parts has been studied.

[0003] As a member for containers, for example, in a transport container, there are resin holders and the like that play a role of storing and protecting electronic-related parts such as chips. However, conventional members for containers have insufficient antistatic properties, attract dust and dirt derived from the environment, and have a problem of adversely affecting the stored chips.

[0004] Therefore, for example, in Patent Document 1, an antistatic property is imparted to a polycarbonate resin by adding a polyamide-polyether block copolymer to the polycarbonate resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1, mentioned above, includes polytetrafluoroethylene resin for the purpose of imparting flame retardancy, in addition to polycarbonate resin and polyamide / polyether block copolymer. When polytetrafluoroethylene resin is blended with polycarbonate resin, fluoride ions derived from the polytetrafluoroethylene resin are included. Furthermore, since polycarbonate resin and polyamide / polyether block copolymer also contain impurity ions such as sulfate ions and calcium ions, when a component for a transport container is molded, there is a risk that electronic components inside the transport container may be damaged by these impurity ions, making it unsuitable for transport container applications.

[0007] Therefore, there is a need for polycarbonate resin pellets that do not contain fluoride ions, have extremely low levels of impurity ions such as sulfate ions and calcium ions, and can form molded products with antistatic properties.

[0008] The present invention relates to an antistatic polycarbonate resin composition pellet and a method for producing the same, which can form molded products that have excellent antistatic properties, contain very few impurity ions such as anions (fluoride ions, sulfate ions, etc.) and cations (calcium ions, etc.), exhibit little color change due to heat, and have rigidity suitable for use in transport containers and the like. [Means for solving the problem]

[0009] The present invention relates to the following [1] to [3]. [1] A polycarbonate resin composition pellet comprising 100 parts by weight of a resin component consisting of an aromatic polycarbonate resin (A) and an acrylonitrile-butadiene-styrene copolymer (B), 5 to 20 parts by weight of a polyamide-polyether block copolymer (C), and 0.1 to 2.0 parts by weight of a phosphate ester compound (D), wherein the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09, wherein the fluoride ion concentration eluted from 30 g of pellets in 30 mL of 50°C hot water for 3 hours is less than 1 μg / L, the sulfate ion concentration is less than 30 μg / L, and the calcium ion concentration is less than 30 μg / L. [2] A method for producing antistatic polycarbonate resin composition pellets, comprising a melt-kneading step of melt-kneading a raw material in a twin-screw extruder, the raw material comprising 100 parts by weight of a resin component consisting of an aromatic polycarbonate resin (A) and an acrylonitrile-butadiene-styrene copolymer (B), 5 to 20 parts by weight of a polyamide-polyether block copolymer (C), and 0.1 to 2.0 parts by weight of a phosphate ester compound (D), wherein the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09; and a cooling step of extruding the melt-kneaded material from a nozzle and cooling the resulting strand with water having an electrical conductivity of 5 μS / cm or less. [3] A carrier case containing the antistatic polycarbonate resin composition pellets described in [1]. [Effects of the Invention]

[0010] The antistatic polycarbonate resin composition pellets of the present invention exhibit excellent antistatic properties, contain extremely low levels of impurity ions such as fluoride ions, sulfate ions, and calcium ions, and exhibit minimal color change due to heat. They also provide the excellent effect of forming molded products with rigidity suitable for applications such as transport containers. [Modes for carrying out the invention]

[0011] [Antistatic polycarbonate resin composition pellets] The antistatic polycarbonate resin composition pellets of the present invention contain, per 100 parts by weight of a resin component consisting of an aromatic polycarbonate resin (A) and an acrylonitrile-butadiene-styrene copolymer (B), 5 to 20 parts by weight of a polyamide-polyether block copolymer (C) and 0.1 to 2.0 parts by weight of a phosphate ester compound (D), and the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09.

[0012] In the present invention, "aromatic polycarbonate resin (A)" is a polymer obtained by a phosgene method, which involves reacting various dihydroxydiaryl compounds with phosgene, or by a transesterification method, which involves reacting dihydroxydiaryl compounds with carbonate esters such as diphenyl carbonate. A typical example is an aromatic polycarbonate resin produced from 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A).

[0013] The above dihydroxydiaryl compounds include, in addition to bisphenol A, bis(hydroxyaryl)alkanes such as 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-tertiary butylphenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, and 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane; 1,1-bis(4-hydroxyphenyl) Examples include bis(hydroxyaryl)cycloalkanes such as roxyphenyl)cyclopentane and 1,1-bis(4-hydroxyphenyl)cyclohexane; dihydroxydiaryl ethers such as 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether; dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide; dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; and dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone. These are used individually or in combination of two or more. In addition to these, piperazine, dipiperidylhydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, etc. may be used in combination.

[0014] Furthermore, the above-mentioned dihydroxyaryl compounds may be mixed with trivalent or higher phenol compounds as shown below. Examples of trivalent or higher phenol compounds include phloroglucin, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene, 2,4,6-trimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane, 1,3,5-tri-(4-hydroxyphenyl)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane, and 2,2-bis-[4,4-(4,4'-dihydroxydiphenyl)-cyclohexyl]-propane.

[0015] The viscosity-average molecular weight of the aromatic polycarbonate resin (A) is preferably between 17,000 and 28,000. Aromatic polycarbonate resins having such a viscosity-average molecular weight are preferable because they possess a certain level of mechanical strength and good fluidity during molding. If the molecular weight is less than 17,000, the molded product may not have sufficient strength, and if the molecular weight exceeds 28,000, the fluidity may be poor. Furthermore, if the molecular weight exceeds 28,000, it is necessary to raise the molding temperature to increase the fluidity of the resin, but raising the molding temperature can cause resin decomposition and increase the amount of phenols, which is undesirable.

[0016] The phenols in aromatic polycarbonate resin (A) refer to phenol compounds contained in raw materials such as monovalent phenol for end-binding, PTBP, and / or bisphenol A, and include unreacted and decomposed raw materials. The concentration of phenols is preferably less than 30 ppm, and more preferably 10 ppm or less. Such aromatic polycarbonate resins have good fluidity during molding, and even at high compounding temperatures, the decomposition of the aromatic polycarbonate resin does not progress, and the amount of phenols does not increase. For example, phenols that cause surface contamination of electronic components housed in the molded product are sufficiently volatilized during the compounding process, so it can be used as a material with an extremely low phenol content without the need for degassing processes such as venting. If the concentration of phenols exceeds 30 ppm, phenols volatilizing from the molded product cannot be ignored, and there is a possibility that they may cause surface contamination of electronic components housed in the molded product.

[0017] <Analysis method> The phenol concentration can be determined by dissolving 1.0 g of polycarbonate resin composition pellet in 20 mL of dichloromethane, then adding 90 mL of methanol dropwise to precipitate the aromatic polycarbonate resin, concentrating the supernatant, and measuring this concentrate using high-performance liquid chromatography.

[0018] Methods for reducing phenols include repeatedly washing aromatic polycarbonate resins.

[0019] "Acrylonitrile-butadiene-styrene copolymer (B)" (commonly known as ABS resin) is a styrene-based resin reinforced with rubber components. By blending ABS resin with aromatic polycarbonate resin, it is possible to further reduce the surface resistance of the resulting molded product and improve its antistatic properties compared to molding with aromatic polycarbonate resin alone and an antistatic agent.

[0020] The ABS resin is not particularly limited as long as it is mainly composed of a copolymer of acrylonitrile-butadiene-styrene, and may contain other monomers, or it may be a graft copolymer. The ABS resin may be prepared according to known methods, or a commercially available product may be used, or two or more may be used in combination. Among these, the resin obtained by bulk polymerization is preferred because it has fewer impurities and excellent color.

[0021] The resin component in this invention consists of an aromatic polycarbonate resin (A) and an ABS resin (B). The combination of component (A) and component (B) is not particularly limited, and a polymer alloy, which is a blend of component (A) and component (B), may be used. In addition, other resins may be included as long as they do not impair the effects of this invention.

[0022] The weight ratio (component (A) / component (B)) of aromatic polycarbonate resin (A) to ABS resin (B) is preferably 50 / 50 to 90 / 10, and more preferably 60 / 40 to 80 / 20, from the viewpoint of improving heat resistance and antistatic properties.

[0023] The "polyamide-polyether block copolymer (C)" can be any copolymer whose main component is a block copolymer in which polyamide and polyether are linked via ester bonds. The polyamide portion can improve the dispersibility and strength of the resin component, while the polyether portion can improve the antistatic properties.

[0024] Examples of polyamide constituent units include nylon 6, nylon 66, nylon 11, and nylon 12. Examples of polyether constituent units include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and polyethylene glycol adducts. These can be used individually or in combination of two or more.

[0025] As the polyamide-polyether block copolymer (C), one prepared according to known methods may be used, a commercially available product may be used, or two or more may be used in combination. Suitable commercially available products include, for example, the "Perestat®" series and "Perectron®" series from Sanyo Chemical Industries, the "Ilgastat® P" series from BASF, and the "Pebax®" series from Arkema.

[0026] The content of polyamide-polyether block copolymer (C) is preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and even more preferably 7 parts by weight or more, per 100 parts by weight of the resin component, from the viewpoint of improving antistatic properties, and preferably 20 parts by weight or less, more preferably 18 parts by weight or less, and even more preferably 16 parts by weight or less, from the viewpoint of reducing impurity ions and maintaining the rigidity of the resulting resin composition. If the rigidity decreases, the shape cannot be maintained when a load is applied, which is undesirable for a housing.

[0027] The "phosphate ester compound (D)" can be a compound represented by the following general formula (I). In this invention, it is presumed that by incorporating the phosphate ester compound (D), the transesterification reaction between the aromatic polycarbonate resin (A) and the polyamide-polyether block copolymer (C) can be suppressed, thereby enabling the production of pellets with improved antistatic properties. Formula (I): O=P(OH) n (OR) 3-n [In formula (I), R is an alkyl group or an aryl group, which may be the same or different, and n is an integer from 0 to 3.]

[0028] In the above general formula (I), R is preferably an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms, and more preferably an alkyl group having 2 to 25 carbon atoms. Also, n is preferably 1 or 2.

[0029] Examples of phosphate ester compounds of formula (I) include mono- or di-stearyl acid phosphates, and stearyl phosphate mixed esters (a mixture of approximately 50 mol% monostearyl phosphate and approximately 50 mol% distearyl phosphate, such as "AX-71" manufactured by ADEKA Corporation) are known.

[0030] The content of the phosphate ester compound (D) is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, and even more preferably 0.1 parts by weight or more, per 100 parts by weight of the resin component, from the viewpoint of suppressing the transesterification reaction between the aromatic polycarbonate resin (A) and the polyamide-polyether block copolymer (C), and from the viewpoint of suppressing discoloration, preferably 2.0 parts by weight or less, more preferably 1.0 part by weight or less, and even more preferably 0.5 parts by weight or less. If the content of the phosphate ester compound (D) exceeds 2.0 parts by weight, initial discoloration due to the effect of the additive and hue changes due to heat retention become larger, which is undesirable in terms of the appearance of the molded product.

[0031] The weight ratio of component (D) to component (C) [(D) / (C)] is preferably 0.005 or higher, more preferably 0.009 or higher, and even more preferably 0.01 or higher, from the viewpoint of maintaining the rigidity of the resin composition and suppressing hue changes during heat retention. Furthermore, from the viewpoint of suppressing coloration and hue changes during heat retention, it is preferably less than 0.09, more preferably 0.08 or lower, even more preferably 0.07 or lower, even more preferably 0.06 or lower, and even more preferably 0.05 or lower.

[0032] Furthermore, the antistatic polycarbonate resin composition pellets of the present invention preferably further contain a phosphorus-based antioxidant (E). In the present invention, it is presumed that the further incorporation of a phosphorus-based antioxidant (E) can suppress the deterioration over time of various properties inherent to aromatic polycarbonate resins, such as impact resistance, heat resistance, and thermal stability, without degrading the antistatic performance.

[0033] The phosphorus-based antioxidant (E) is not particularly limited as long as it can be used to obtain the antistatic polycarbonate resin composition pellets that are the target of the present invention, but examples include phosphite ester compounds having the following structure.

[0034] [ka]

[0035] The phosphite ester compound preferably includes at least one compound selected from the phosphite ester compound represented by formula (1), the phosphite ester compound represented by formula (2), the phosphite ester compound represented by formula (3), and the phosphite ester compound represented by formula (4).

[0036] Formula (1): [ka] (In the formula, R 1 (where represents an alkyl group with 1 to 20 carbon atoms, and 'a' represents an integer from 0 to 3.)

[0037] In the above equation (1), R 1 The alkyl group is a C1-C20 alkyl group, but more preferably a C1-C10 alkyl group.

[0038] Examples of compounds represented by formula (1) include triphenyl phosphite, tricresyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, and trisnonylphenyl phosphite. Among these, tris(2,4-di-t-butylphenyl) phosphite is preferred and is commercially available, for example, as Irgaphos 168 manufactured by BASF ("Irgaphos" is a registered trademark of BASF Societas Europia).

[0039] Formula (2): [ka] (wherein, R 2 , R 3 , R 5 and R 6 each independently represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms or a phenyl group. R 4 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. X represents a single bond, a sulfur atom or a group represented by the formula: -CHR 7 -(where R 7 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms). A represents an alkylene group having 1 to 8 carbon atoms or a group represented by the formula: *-COR 8 -(where R 8 represents a single bond or an alkylene group having 1 to 8 carbon atoms, and * represents a bond on the oxygen side). Y and Z are such that one of them represents a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms).)

[0040] R 2 , R 3 , R 5 and R 6Each of these independently represents a hydrogen atom, a C1-C8 alkyl group, a C5-C8 cycloalkyl group, a C6-C12 alkylcycloalkyl group, or a C7-C12 aralkyl or phenyl group. Examples of C1-C8 alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, t-pentyl, i-octyl, t-octyl, and 2-ethylhexyl groups. Examples of C5-C8 cycloalkyl groups include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Examples of C6-C12 alkylcycloalkyl groups include 1-methylcyclopentyl, 1-methylcyclohexyl, and 1-methyl-4-i-propylcyclohexyl groups. Examples of aralkyl groups having 7 to 12 carbon atoms include the benzyl group, α-methylbenzyl group, and α,α-dimethylbenzyl group.

[0041] The aforementioned R 2 , R 3 and R 5 Each of these is preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or an alkylcycloalkyl group having 6 to 12 carbon atoms. In particular, R 2 and R 5 Each of these is preferably independently a t-alkyl group such as a t-butyl group, a t-pentyl group, or a t-octyl group, a cyclohexyl group, or a 1-methylcyclohexyl group. 3 The group is preferably a C1-C5 alkyl group such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, or t-pentyl group, and more preferably a methyl group, t-butyl group, or t-pentyl group.

[0042] The aforementioned R 6The group is preferably a hydrogen atom, a C1-C8 alkyl group, or a C5-C8 cycloalkyl group, and more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, or a t-pentyl group, which are C1-C5 alkyl groups.

[0043] In equation (2), R 4 R represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of alkyl groups having 1 to 8 carbon atoms include the aforementioned R. 2 , R 3 , R 5 and R 6 Examples of alkyl groups are given in the explanation. Among them, R 4 It is preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and more preferably a hydrogen atom or a methyl group.

[0044] In formula (2), X is a single bond, a sulfur atom, or a compound of the formula -CHR. 7 This indicates a group represented by -. Here, the formula is -CHR 7 -R inside 7 R represents a hydrogen atom, a C1-C8 alkyl group, or a C5-C8 cycloalkyl group. Examples of C1-C8 alkyl groups and C5-C8 cycloalkyl groups are, for example, the R group. 2 , R 3 , R 5 and R 6 Examples of alkyl groups and cycloalkyl groups are given in the description. In particular, X is preferably a single bond, a methylene group, or a methylene group substituted with a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, etc., and more preferably a single bond.

[0045] In formula (2), A is an alkylene group having 1 to 8 carbon atoms or formula:*-COR 8This indicates a group represented by -. Examples of alkylene groups having 1 to 8 carbon atoms include methylene, ethylene, propylene, butylene, pentamethylene, hexamethylene, octamethylene, and 2,2-dimethyl-1,3-propylene, with propylene being preferred. Also, formula: *-COR 8 -R in 8 R represents a single bond or an alkylene group having 1 to 8 carbon atoms. 8 Examples of alkylene groups having 1 to 8 carbon atoms that exhibit this property include the alkylene groups exemplified in the explanation of A above. 8 It is preferably a single bond or an ethylene group. Also, formula: *-COR 8 The asterisk (*) in the - indicates the oxygen-side bond, showing that the carbonyl group is bonded to the oxygen atom of the phosphite group.

[0046] In formula (2), Y and Z represent either a hydroxyl group, a carbon-1 to carbon-8 alkoxy group, or a carbon-7 to carbon-12 aralkyloxy group, and the other a hydrogen atom or a carbon-1 to carbon-8 alkyl group. Examples of carbon-1 to carbon-8 alkoxy groups include methoxy, ethoxy, propoxy, t-butoxy, and pentyloxy groups. Examples of carbon-7 to carbon-12 aralkyloxy groups include benzyloxy, α-methylbenzyloxy, and α,α-dimethylbenzyloxy groups. Examples of carbon-1 to carbon-8 alkyl groups include the aforementioned R. 2 , R 3 , R 5 and R 6 Examples of alkyl groups are given in the explanation.

[0047] Examples of compounds represented by formula (2) include 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosfepine, 6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosfepine, 6 Examples include -[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-4,8-di-t-butyl-2,10-dimethyl-12H-dibenzo[d,g][1,3,2]dioxaphosphosine and 6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-4,8-di-t-butyl-2,10-dimethyl-12H-dibenzo[d,g][1,3,2]dioxaphosphosine. Among these, when using antistatic polycarbonate resin composition pellets obtained for transport containers for electronic components, etc., 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosfepine is preferred, and is commercially available, for example, as Sumirizer GP ("Smirizer" is a registered trademark) manufactured by Sumitomo Chemical Co., Ltd.

[0048] Formula (3): [ka] (In the formula, R 9 and R 10 Each of the following independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and each of the following independently represents an integer from 0 to 3.

[0049] Examples of compounds represented by formula (3) include bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, and phenylbisphenol A pentaerythritol diphosphite. Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite is commercially available as "ADEKA Stab PEP-24G" from ADEKA, and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite is commercially available as "ADEKA Stab PEP-36" from ADEKA.

[0050] Formula (4): [ka] (In the formula, R 11 ~R 18 Each of these independently represents an alkyl or alkenyl group having 1 to 3 carbon atoms. 11 and R 12 , R 13 and R 14 , R 15 and R 16 , R 17 and R 18 These elements may be joined together to form a ring. 19 ~R 22 Each of these independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. d to g are each independently integers from 0 to 5. 1 ~X 4 Each of these independently represents a single bond or a carbon atom. 1 ~X 4 If it is a single bond, R 11 ~R 22 Of these, the functional group attached to the single bond in question is excluded from general formula (4).

[0051] A specific example of the compound represented by formula (4) is bis(2,4-dicumylphenyl)pentaerythritol diphosphite. This is commercially available as "Doverphos® S-9228" from Dover Chemical and "ADEKA Stab PEP-45" from ADEKA.

[0052] Furthermore, instead of the compounds represented by formulas (1) to (4) above, or in addition to any of the compounds represented by formulas (1) to (4) above, the compound represented by formula (5) below may be used.

[0053] Formula (5): [ka] (In the formula, R 23 ~R 26 (This represents an alkyl group having 1 to 20 carbon atoms, or an aryl group which may be substituted with an alkyl group.)

[0054] Specific examples of compounds represented by formula (5) include, for example, [1,1'-biphenyl]-4,4-diylbis[bis(2,4-di-t-butylphenoxy)phosphine], for which "Irgaphos P-EPQ" from BASF and "Sandstab P-EPQ" from Clariant Japan are commercially available.

[0055] Furthermore, in the present invention, phosphoric acid can be used as a phosphorus-based antioxidant. Phosphoric acid is a non-volatile weak acid and commercially available products can be used; there are no particular limitations. Examples include phosphoric acid manufactured by Nacalai Tesque and phosphoric acid manufactured by Wako Pure Chemical Industries.

[0056] The amount of phosphorus-based antioxidant (E) added is preferably 0.01 parts by weight or more, more preferably 0.03 parts by weight or more, and preferably 0.1 parts by weight or less, and more preferably 0.08 parts by weight or less, per 100 parts by weight of the resin component. Amounts exceeding 0.1 parts by weight are undesirable because they lead to a decrease in physical properties, insufficient thermal stability during retention in the molding process, and discoloration.

[0057] The antistatic polycarbonate resin composition pellets of the present invention may contain, in addition to the components described above, heat stabilizers, other antioxidants, pigments, colorants, mold release agents, softeners, flame retardants, ultraviolet absorbers, other antistatic agents, and impact modifiers, to the extent that they do not impair the effects of the present invention. Furthermore, other polymer materials and other resin compositions may be included to the extent that they do not hinder the effects of the present invention. The content of these materials can be appropriately adjusted according to known art.

[0058] The antistatic polycarbonate resin composition pellets of the present invention can be prepared using raw materials that contain 5 to 20 parts by weight of polyamide-polyether block copolymer (C) and 0.1 to 2.0 parts by weight of phosphate ester compound (D) per 100 parts by weight of resin component consisting of aromatic polycarbonate resin (A) and acrylonitrile-butadiene-styrene copolymer (B), and the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09. For example, aromatic polycarbonate resin (A), acrylonitrile-butadiene-styrene copolymer (B), polyamide-polyether block copolymer (C), and phosphate ester compound (D), along with other optionally blended components, can be mixed in any known mixer, such as a tumbler and ribbon blender, and then melt-kneaded in a conventional single-screw or twin-screw extruder. The resulting molten mixture is cooled with water having an electrical conductivity of 5 μS / cm or less, for example, so that the impurity ion content is within a specific range, and then processed into pellets to obtain the pellets of the present invention. The pellets may be dried or cooled.

[0059] The shape and size of the pellets of the present invention are not particularly limited, and any shape and size common to resin pellets is acceptable. For example, the pellet shape can be an elliptical column or a cylindrical shape. The size of the pellet is preferably about 2 to 8 mm in length, and in the case of an elliptical column, the major axis of the ellipse cross-section is preferably about 2 to 8 mm and the minor axis is preferably about 1 to 4 mm, and in the case of a cylindrical shape, the diameter of the circle cross-section is preferably about 1 to 6 mm. Note that each individual pellet obtained may be of this size, all pellets forming a pellet aggregate may be of this size, or the average size of the pellet aggregate may be of this size, and there are no particular limitations.

[0060] Generally, polycarbonate resin composition pellets contain impurity ions such as sulfate ions and calcium ions derived from the raw materials. For example, when a polyamide-polyether block copolymer distributed on the market is analyzed under the following conditions, the fluoride ion concentration is about 70-90 μg / L, the sulfate ion concentration is about 14,000-16,000 μg / L, and the calcium ion concentration is about 550-750 μg / L. On the other hand, the antistatic polycarbonate resin composition pellets of the present invention are characterized by having an extremely low content of these impurity ions. Specifically, the antistatic polycarbonate resin composition pellets of the present invention contain fluoride ions (F - ) The concentration is less than 1 μg / L (ppb), and sulfate ions (SO4 2- The concentration is less than 30 μg / L (ppb), preferably less than 20 μg / L, and calcium ions (Ca 2+The concentration is less than 30 μg / L (ppb), preferably less than 20 μg / L. In the antistatic polycarbonate resin composition of the present invention, if the content of the aforementioned impurity ions is within the above range, surface contamination by impurity ions derived from the resulting molded product can be reduced. The method of adjusting the content of impurity ions is not particularly limited as long as it is within the above range. For example, when preparing the antistatic polycarbonate resin composition pellets of the present invention, the concentration of these impurity ions can be reduced by adjusting the electrical conductivity of the water used during cooling after melting and kneading. Specifically, the electrical conductivity of the cooling water is preferably 5 μS / cm or less, more preferably 1 μS / cm or less. The lower limit is not particularly limited, but for example, it is about 0.01 μS / cm. Any water exhibiting an electrical conductivity within the above range can be used without particular limitation. For example, ion-exchanged water adjusted through an ion-exchange membrane can be suitably used, and it may be pure water that has been ion-exchanged, industrial water that has been ion-exchanged, or tap water that has been ion-exchanged. Cooling is not particularly limited as long as the water exhibiting the aforementioned electrical conductivity is used; it may be performed by continuous flow or by immersion in water filled with a water bath. The market requirements for these impurity ion concentrations are less than 1 μg / L for fluoride ions, about 30 μg / L for sulfate ions, and about 30 μg / L for calcium ions.

[0061] The concentration of impurity ions can be measured by the following method. <Analysis method> The elution can be performed by placing 30 g of polycarbonate resin composition pellets in 30 mL of 50°C pure water, holding for 3 hours to elute impurity ions, and then determining the composition by ion chromatography after cooling. During elution, the mixture should be stirred at a speed that does not cause the pellets to escape from the elution solution, and it is acceptable for the pellets to be damaged or to maintain their initial shape due to the stirring. The elution solution should be kept warm in a water bath at 50°C (preferably within a temperature range of 50 ± 1°C).

[0062] [Method for producing antistatic polycarbonate resin composition pellets] The polycarbonate resin composition pellets according to this embodiment can be manufactured, for example, by a manufacturing method that includes a melt-kneading step and a cooling step, as detailed below.

[0063] In the melt-kneading process, an aromatic polycarbonate resin (A), an acrylonitrile-butadiene-styrene copolymer (B), a polyamide-polyether block copolymer (C), and a phosphate ester compound (D) are melt-kneaded in an extruder. Other optional components can be added here. Examples of extruders include twin-screw extruders such as mesh-type co-rotating twin-screw extruders and multi-screw extruders with two or more shafts, but a mesh-type co-rotating twin-screw extruder is preferred. The twin-screw extruder preferably includes a hopper which is a raw material supply port, an intermediate supply port, a vent, a jacketed cylinder, a die head, etc.

[0064] Vents are used to discharge ions, gases, and other substances from inside the twin-screw extruder, and it is preferable that at least one vent be provided in a suitable location on the twin-screw extruder (for example, between the hopper and the intermediate feed port, or between the intermediate feed port and the die head). The vacuum pressure of the vent is preferably 10 to 30 kPa (gauge pressure: -0.091 MPa to -0.071 MPa).

[0065] The mixing temperature in the melt-mixing process is preferably 230-290°C, and more preferably 240-280°C.

[0066] In the cooling process, the molten mixture is extruded from a nozzle, the resulting strand is taken up by a roller, and cooled in a water bath filled with, for example, ion-exchanged water. The cooling time is not particularly limited; it should be cooled until the strand reaches a temperature at which it can be cut. To obtain pellets with few impurity ions, the electrical conductivity of the water used is preferably 5 μS / cm or less, and more preferably 1 μS / cm or less. Using a water bath filled with water of such electrical conductivity makes it possible to obtain pellets with few impurity ions. The water temperature of the water bath is preferably around 20 to 80°C. Furthermore, it is preferable to control the electrical conductivity of the water bath by circulating it through, for example, a heat exchanger or filter (such as an ion exchange membrane) made of clean material, while maintaining a constant electrical conductivity. The combination of cooling by water bath and the vent described above is particularly effective in reducing impurity ions in polycarbonate resin composition pellets.

[0067] After cooling, the strands are cut into pellets using a known pelletizer or similar device.

[0068] The antistatic polycarbonate resin composition pellets obtained in this way can be molded by known molding methods. Because the pellets of this invention have antistatic properties, the molded articles have excellent antistatic properties. Furthermore, because they contain very few impurity ions such as fluoride ions, sulfate ions, and calcium ions, the resulting molded articles can reduce environmental pollution. In addition, it is possible to produce molded articles with good appearance and minimal change in hue during processing.

[0069] The polycarbonate resin molded articles of the present invention have good moldability of the antistatic polycarbonate resin composition pellets, excellent antistatic properties and heat resistance, and contain very few impurity ions, making them suitable for use, for example, as housings for electronic components and transport container components.

[0070] For example, a carrier case obtained by molding the antistatic polycarbonate resin composition pellets of the present invention has a surface resistivity of 1 × 10¹⁶ when measured by the MCC method using a Hi-Resta UX (MCP-HT800) manufactured by Nitto Seikou Analytech. 9 ~1 × 10 12 With a capacitance of Ω / □, it exhibits excellent antistatic properties and possesses heat resistance derived from polycarbonate resin, making it suitable for use as a carrier case for electronic components. [Examples]

[0071] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way by these examples.

[0072] Examples 1-6 and Comparative Examples 1-4 The ingredients used are listed below. (A) Aromatic polycarbonate resin Aromatic polycarbonate resin synthesized from bisphenol A and phosgene Viscosity-average molecular weight 23,000, phenol concentration 10 ppm or less, manufactured by Sumika Polycarbonate, "SD Polycarbonate (registered trademark) 200-8" (B)ABS resin Clarastic (registered trademark) AT-05: Manufactured by A&L Japan. (C) Polyamide-polyether block copolymer Pelektron (registered trademark) AS: Manufactured by Sanyo Chemical Industries, Ltd. (D) Phosphate ester compounds Stearyl phosphate mixed ester (a mixture of approximately 50 mol% monostearyl phosphate and approximately 50 mol% distearyl phosphate), ADEKA AX-71 stub. (E) Phosphite-based antioxidants Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (IUPAC name: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane), represented by the following formula, is available in ADEKA's ADEKA stub "PEP-36". [ka]

[0073] A twin-screw extruder (manufactured by Japan Steel Works, TEK-51MHS) was used, with the mixing zone temperature set to 250°C and the screw rotation speed to 500 rpm. The above components were dry-mixed using a tumbler in the weight ratios shown in Table 1. The raw materials were then supplied from a hopper located at the uppermost part of the twin-screw extruder and extruded through a vent (vacuum 20 kPa) on the downstream side of the mixing zone via the die head to prepare a strand-like molten mixture. The obtained molten mixture was cooled with ion-exchanged water (electrical conductivity 1.0 μS / m or less) or water that does not pass through an ion-exchange membrane (electrical conductivity 20 μS / m), and then pelletized to obtain polycarbonate resin composition pellets. The obtained pellets were used for the following various evaluations. The results are shown in Table 1.

[0074] Test Example 1 (Impure Ion Concentration) 30 g of the obtained pellet was placed in 30 mL of pure water at 50°C, and dissolved for 3 hours while stirring gently to prevent the pellet from splashing out. After cooling, the fluoride ion concentration, sulfate ion concentration, and calcium ion concentration were measured by ion chromatography. The sample was considered acceptable if the fluoride ion concentration was less than 1 μg / L, the sulfate ion concentration was less than 30 μg / L, and the calcium ion concentration was less than 30 μg / L.

[0075] Test Example 2 (Antistatic Properties) After drying the obtained pellets at 100°C for 4 hours, a flat plate test specimen (150mm × 90mm × 2mm) was fabricated using an injection molding machine (FANUC ROBOSHOT S2000i100B) at a set temperature of 260°C and an injection pressure of 55MPa. The surface resistivity (Ω / □) near the center of the plate surface was measured using a high-resistivity resistivity meter (Nitto Seikou Analytech Highresta UX MCP-HT800) at an applied voltage of 1000V. 13 If Ω / □ is less than or equal to 1 × 10 13 If the ratio exceeded Ω / □, the student failed.

[0076] Test Example 3 (Flexural Modulus) The obtained pellets were dried at 100°C for 4 hours. Then, test specimens were prepared using an injection molding machine (FANUC ROBOSHOT S2000i100B) at a set temperature of 250°C in accordance with the ISO test method. The flexural modulus of the obtained test specimens was measured in accordance with ISO 178. A flexural modulus of 1800 MPa or higher was considered acceptable.

[0077] Test Example 4 (Hue) After drying the obtained pellets at 100°C for 4 hours, a flat plate test specimen 1 (150mm × 90mm × 2mm) was fabricated using an injection molding machine (FANUC ROBOSHOT S2000i100B) at a set temperature of 260°C and an injection pressure of 55MPa. Similarly, a flat plate test specimen 2 was fabricated using the same method, after leaving the resin pellets in a cylinder at 260°C for 10 minutes and then injecting them at an injection pressure of 55MPa. Next, the yellowness (YI) was measured using a spectrophotometer (Murakami Color Research Institute CMS-35SP) with a D65 light source, a viewing angle of 10°, and the reflectance method. The YI of flat plate test specimen 1 was defined as the initial YI, and ΔYI was calculated by subtracting the YI of flat plate test specimen 1 from the YI of flat plate test specimen 2. Test specimens with an initial YI of less than 40 and a ΔYI of less than 3 were considered acceptable.

[0078] [Table 1]

[0079] From the above results, it can be seen that the antistatic polycarbonate resin composition pellets of the present invention have excellent antistatic properties and appearance. Furthermore, they contain very few impurity ions such as fluoride ions, sulfate ions, and calcium ions, making them suitable for use as components for transport containers where surface contamination reduction is required.

[0080] In contrast, Comparative Example 1 had an excessively high weight ratio of component (D) to component (C) [(D) / (C)], resulting in discoloration from the initial state and significant color change due to heat retention, leading to an inferior appearance. Comparative Example 2 had an excessively high content of component (C), resulting in high concentrations of sulfate and calcium ions even when treated with cooling water with an electrical conductivity of 1.0 μS / m or less. Furthermore, the resulting molded product could not maintain its rigidity and exhibited significant color change due to heat retention. Comparative Example 3 did not contain component (D), resulting in significant color change due to heat retention and an inferior appearance. Comparative Example 4 exhibited excellent antistatic properties and suppressed color change, but the electrical conductivity of the water used for cooling was 20 μS / m, resulting in a high concentration of impurity ions. Therefore, it is considered difficult to apply it to transport containers for precision machinery such as semiconductor wafers. [Industrial applicability]

[0081] The polycarbonate resin composition pellets of the present invention can be suitably used as housing components for semiconductor wafer transport containers and the like, where surface contamination reduction and antistatic effect are required.

Claims

1. A polycarbonate resin composition pellet comprising 100 parts by weight of a resin component consisting of an aromatic polycarbonate resin (A) and an acrylonitrile-butadiene-styrene copolymer (B), 5 to 20 parts by weight of a polyamide-polyether block copolymer (C), and 0.1 to 2.0 parts by weight of a phosphate ester compound (D), wherein the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09, An antistatic polycarbonate resin composition pellet in which, after holding a 30g pellet in 30mL of 50°C hot water for 3 hours, the eluted fluoride ion concentration is less than 1 μg / L, the sulfate ion concentration is less than 30 μg / L, and the calcium ion concentration is less than 30 μg / L.

2. The antistatic polycarbonate resin composition pellet according to claim 1, wherein the aromatic polycarbonate resin (A) contains bisphenol A as a raw material monomer.

3. The antistatic polycarbonate resin composition pellet according to claim 1, wherein the phosphate ester compound (D) is a compound represented by the following general formula (I). Formula (I): O=P(OH) ｎ (OR) ３－ｎ [In formula (I), R is an alkyl group or an aryl group, which may be the same or different, and n is an integer from 0 to 3.]

4. The antistatic polycarbonate resin composition pellet according to claim 3, wherein the compound represented by general formula (I) comprises a mixture of monostearyl phosphate and distearyl phosphate.

5. Furthermore, the antistatic polycarbonate resin composition pellet according to claim 1 contains 0.01 to 0.1 parts by weight of a phosphorus-based antioxidant (E).

6. The antistatic polycarbonate resin composition pellet according to claim 5, wherein the phosphorus-based antioxidant (E) is tris(2,4-di-t-butylphenyl) phosphite or bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (IUPAC name: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane).

7. The antistatic polycarbonate resin composition pellet according to claim 1, wherein the viscosity-average molecular weight of the aromatic polycarbonate resin (A) is 17,000 to 28,000, and the phenol concentration is less than 30 ppm.

8. The antistatic polycarbonate resin composition pellet according to claim 1, wherein a 150 mm × 90 mm × 2 mm flat test piece, manufactured by an injection molding machine at a molding temperature of 260°C, has a YI of less than 40 when measured with a spectrophotometer (CMS-35SP manufactured by Murakami Color Research Institute), and the change in YI after 10 minutes of residence at 260°C is less than 3.

9. A method for producing antistatic polycarbonate resin composition pellets, comprising: a melt-kneading step of melt-kneading a raw material in a twin-screw extruder, the raw material comprising 100 parts by weight of a resin component consisting of an aromatic polycarbonate resin (A) and an acrylonitrile-butadiene-styrene copolymer (B), 5 to 20 parts by weight of a polyamide-polyether block copolymer (C), and 0.1 to 2.0 parts by weight of a phosphate ester compound (D), wherein the weight ratio of component (D) to component (C) [(D) / (C)] is 0.005 or more and less than 0.09; and a cooling step of extruding the melt-kneaded material from a nozzle and cooling the resulting strand with water having an electrical conductivity of 5 μS / cm or less.

10. A carrier case comprising a molded article made of antistatic polycarbonate resin composition pellets according to any one of claims 1 to 8.

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