Polycarbonate resin composition pellet and method for producing the same

Abstract

To provide a polycarbonate resin composition pellet capable of forming a molded article having excellent slipperiness and wear resistance and extremely low impurity ions such as fluoride ions, chloride ions and sulfate ions and to provide a method for producing the same.SOLUTION: There is provided a polycarbonate resin composition pellet which contains 4.0 to 15.0 pts.wt. of a maleic anhydride-modified ultra-high molecular weight polyethylene resin (B) and 0.3 pt.wt. of a phosphorous acid-based antioxidant (C) based on 100 pts.wt. of an aromatic polycarbonate resin (A) and contains not more than 0.1 pt.wt. of a fluorine-based resin (D), wherein the coefficient of kinetic friction of a 150 mm×90 mm×2 mm flat test piece prepared by injection molding is less than 0.3 when friction is applied at a speed of 100 mm / min with a gauze with a load of 200 g on a 63.5 mm x 63.5 mm flat indenter.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to polycarbonate resin composition pellets and a method for producing the same. [Background technology]

[0002] Polycarbonate resin is a thermoplastic resin that has excellent transparency, impact resistance, heat resistance, thermal stability, etc., and is widely used in fields such as electrical and electronics, ITE, machinery, and automobiles. Recently, however, due to its excellent heat resistance, thermal stability, impact resistance, etc., it has also been used for container materials for electronic-related parts, etc.

[0003] Examples of container members include resin holders that store and transport electronic components such as chips in a transport container. Electronic components may come into contact with and slide on the resin container member. Conventional container members do not have sufficient sliding properties against electronic components, so that the electronic components cannot move smoothly on the container member. This can lead to problems such as the electronic components being unable to be smoothly removed from the container member and the surfaces of the electronic components being finely damaged. Furthermore, friction between the electronic components and the container member can cause the container member to be scraped off, resulting in the generation of particles.

[0004] In order to overcome the above drawbacks, a resin composition in which a polytetrafluoroethylene resin is blended with a polycarbonate resin has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1-259059 Summary of the Invention [Problem to be solved by the invention]

[0006] Polycarbonate resin contains impurity ions such as sulfate ions, in addition to chloride ions derived from the raw material phosgene. When polycarbonate resin is mixed with polytetrafluoroethylene resin, fluoride ions derived from polytetrafluoroethylene resin are also contained. When a transport container is molded from pellets containing impurity ions, the impurity ions may damage the precision materials inside the transport container. Some organic fluorine compounds are also subject to international regulations, and there are moves to strengthen these regulations.

[0007] Therefore, there is a demand for polycarbonate resin pellets that can be used to form molded articles having excellent friction and wear properties and containing very little impurity ions such as fluoride ions, chloride ions, sulfate ions, etc. However, such polycarbonate resin composition pellets and a method for producing the same have not been investigated so far.

[0008] Therefore, an object of the present invention is to provide polycarbonate resin composition pellets which have excellent lubricity and abrasion resistance and can form molded articles with extremely low amounts of impurity ions such as fluoride ions, chloride ions and sulfate ions, and a method for producing the same. [Means for solving the problem]

[0009] The polycarbonate resin composition pellets according to the present invention contain 4.0 to 15.0 parts by weight of maleic anhydride modified ultra-high molecular weight polyethylene resin (B) and up to 0.3 part by weight of a phosphorous acid-based antioxidant (C) per 100 parts by weight of aromatic polycarbonate resin (A), and do not contain more than 0.1 part by weight of a fluororesin (D). The polycarbonate resin composition pellets are characterized in that they have a dynamic friction coefficient of less than 0.3 when a 150 mm x 90 mm x 2 mm polycarbonate resin plate test piece prepared by injection molding is rubbed with a gauze loaded with a 200 g load using a 63.5 mm x 63.5 mm flat indenter at a speed of 100 mm / min.

[0010] The method for producing polycarbonate resin composition pellets according to this embodiment is characterized by comprising a melt-kneading step of melt-kneading 100 parts by weight of an aromatic polycarbonate resin (A), 4.0 to 15.0 parts by weight of a maleic anhydride modified ultra-high molecular weight polyethylene resin (B), and up to 0.3 parts by weight of a phosphorous acid-based antioxidant (C) in a twin-screw extruder, and a cooling step of extruding the molten mixture from a nozzle and cooling the resulting strands in a pure water bath. Effect of the Invention

[0011] According to the present invention, there are provided polycarbonate resin composition pellets which are capable of forming molded articles having excellent lubricity and abrasion resistance and containing extremely small amounts of impurity ions such as fluoride ions, chloride ions and sulfate ions, and a method for producing the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments will be described in detail. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations of substantially the same configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the inventor provides the following explanations to enable those skilled in the art to fully understand the present invention, and does not intend for the subject matter described in the claims to be limited by them.

[0013] The polycarbonate resin composition pellets according to the present invention contain 100 parts by weight of an aromatic polycarbonate resin (A), 4.0 to 15.0 parts by weight of a maleic anhydride modified ultra-high molecular weight polyethylene resin (B), up to 0.3 parts by weight of a phosphorous acid-based antioxidant (C), and up to 0.1 parts by weight of a fluorine-based resin (D), and are characterized in that a dynamic friction coefficient of less than 0.3 is obtained when a 150 mm x 90 mm x 2 mm flat test piece prepared by injection molding is rubbed with a gauze loaded with a 200 g load using a 63.5 mm x 63.5 mm flat indenter at a speed of 100 mm / min.

[0014] The aromatic polycarbonate resin (A) used in the present invention is a polymer obtained by the phosgene process in which various dihydroxydiaryl compounds are reacted with phosgene, or the ester exchange process in which a dihydroxydiaryl compound is reacted with a carbonate ester such as diphenyl carbonate, and a representative example is an aromatic polycarbonate resin produced from 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A).

[0015] Examples of the dihydroxydiaryl compound 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-tert-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; bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)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'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; and dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone.

[0016] These may be used alone or in combination of two or more. In addition to these, piperazine, dipiperidylhydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, etc. may also be used in combination.

[0017] Furthermore, the above dihydroxyaryl compounds may be used in combination with the following trivalent or higher phenolic compounds: Trivalent or higher phenolic compounds 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)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane, and 2,2-bis-[4,4-(4,4'-dihydroxydiphenyl)-cyclohexyl]-propane.

[0018] The viscosity average molecular weight of the aromatic polycarbonate resin (A) is preferably 18,000 to 23,000. An aromatic polycarbonate resin having such a viscosity average molecular weight has a certain mechanical strength and is preferable because it has good fluidity during molding. If the molecular weight is less than 18,000, the molded product may not be given sufficient strength, and if the molecular weight is more than 23,000, the fluidity may be poor. In this case, phenols, which cause surface contamination of electronic-related parts housed in the molded product, are difficult to volatilize during processing, so the molding temperature needs to be increased, but increasing the molding temperature is not preferable because it may cause resin decomposition and increase the amount of phenols.

[0019] The phenols in the aromatic polycarbonate resin (A) refer to the monohydric phenol for blocking the terminals: PTBP and / or the dihydric phenol compound: bisphenol A, etc., including unreacted and decomposed phenols as raw materials. The concentration of the phenols is preferably less than 30 ppm, more preferably less than 10 ppm. Such aromatic polycarbonate resins have good molding flowability, 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, since the phenols that cause surface contamination of electronic-related parts to be housed in the molded product are sufficiently volatilized in the compounding process, the material can be made with extremely low volatile content without going through a degassing process using a vent. If the concentration of the phenols exceeds 30 ppm, the phenols volatilized from the molded product cannot be ignored, and may cause surface contamination of electronic-related parts to be housed in the molded product.

[0020] <Analysis method> The phenol concentration can be determined by dissolving 1.0 g of polycarbonate pellets in 20 mL of dichloromethane, dropping 90 mL of methanol thereto to precipitate an aromatic polycarbonate resin, concentrating the supernatant, and then measuring the concentrate by high performance liquid chromatography.

[0021] As a method for reducing the amount of phenols, a method of repeatedly washing the aromatic polycarbonate resin can be mentioned.

[0022] The maleic anhydride-modified ultra-high molecular weight polyethylene (B) is a polyethylene resin modified with maleic anhydride, and is a component that imparts slipperiness (low friction) and abrasion resistance to a molded article made of polycarbonate resin composition pellets. The average molecular weight of the maleic anhydride-modified ultra-high molecular weight polyethylene (B) is, for example, 1 million or more. When the maleic anhydride-modified ultra-high molecular weight polyethylene is added to the aromatic polycarbonate resin (A), even when a fluorine-based resin such as polytetrafluoroethylene is not added or the amount of the fluorine-based resin is extremely small, the slipperiness of the aromatic polycarbonate resin composition can be improved, the frictional resistance can be reduced, and the abrasion resistance can be improved. The method of modifying the polyethylene resin is not particularly limited, and for example, maleic anhydride-modified ultra-high molecular weight polyethylene can be obtained by generating radicals in polyethylene in the presence of a peroxide and graft-polymerizing maleic anhydride. The maleic anhydride-modified ultra-high molecular weight polyethylene can be obtained by introducing a functional group into ultra-high molecular weight polyethylene, and a polar group is introduced into the ultra-high molecular weight polyethylene by modifying it with maleic anhydride. In the process for obtaining maleic anhydride-modified ultra-high molecular weight polyethylene, for example, 1.2 parts by weight of maleic anhydride and 1 part by weight of lauroyl peroxide are added to 100 parts by weight of ultra-high molecular weight polyethylene, and the mixture is heated to 200°C or higher to obtain maleic acid-modified ultra-high molecular weight polyethylene. In this process, organic acids such as carboxylic acids and sulfonic acids, and inorganic oxyacids such as sulfuric acid and nitrous acid may be used in combination to increase reactivity. While the use of these acids can relatively increase stability, they can also result in the inclusion of sulfuric acid (SO4) in the maleic anhydride-modified high molecular weight polyethylene produced. 2- In some cases, anions such as those mentioned above may remain, making it difficult to use the material in highly clean applications such as semiconductor applications, which require minimal contamination with impurities. In consideration of the properties of maleic anhydride-modified high molecular weight polyethylene, the present inventors have proposed a method for solving the problem of the required cleanliness of the material in the method for producing pellets of the present invention, which will be described later.

[0023] The content of the maleic anhydride-modified ultra-high molecular weight polyethylene (B) is preferably 4.0 to 15.0 parts by weight per 100 parts by weight of the aromatic polycarbonate resin (A). When the content of the maleic anhydride-modified ultra-high molecular weight polyethylene (B) is less than 4.0 parts by weight per 100 parts by weight of the aromatic polycarbonate resin (A), it becomes difficult to sufficiently improve the sliding properties and the friction and wear properties. When the content of the maleic anhydride-modified ultra-high molecular weight polyethylene (B) is more than 15.0 parts by weight per 100 parts by weight of the aromatic polycarbonate resin (A), the compatibility between the aromatic polycarbonate resin (A) and the maleic anhydride-modified ultra-high molecular weight polyethylene (B) is poor, so that the maleic anhydride-modified ultra-high molecular weight polyethylene (B) is likely to come out to the surface, which is undesirable because it impairs the appearance of the molded product. As the maleic anhydride-modified ultra-high molecular weight polyethylene (B), for example, LUBMER LY1040 manufactured by Mitsui Chemicals, Inc. can be mentioned.

[0024] The aromatic polycarbonate resin composition pellets according to the embodiment contain a phosphorous acid-based antioxidant (C). By blending the maleic anhydride-modified ultra-high molecular weight polyethylene (B) with the aromatic polycarbonate resin (A), it is possible to obtain aromatic polycarbonate resin composition pellets having good slip properties and abrasion resistance. However, when the aromatic polycarbonate resin composition pellets contain the phosphorous acid-based antioxidant (C), it is possible to improve the slip properties and abrasion resistance while suppressing deterioration over time of various properties inherent to the aromatic polycarbonate resin, such as impact resistance, heat resistance, and thermal stability.

[0025] The phosphite-based antioxidant (C) is not particularly limited as long as it can provide the aromatic polycarbonate resin composition of the present invention, but it preferably contains a phosphite compound having the following phosphite structure: [ka]

[0026] In the aromatic polycarbonate resin composition according to an embodiment of the present invention, the phosphite-based antioxidant (C) preferably contains at least one compound selected from the group consisting of a phosphite compound represented by the following formula (1), a phosphite compound represented by the following formula (2), a phosphite compound represented by the following formula (3), and a phosphite compound represented by the following formula (4).

[0027] The phosphite-based antioxidant (C) preferably contains, for example, a compound represented by the following formula (1).

[0028] Formula (1): [ka] (In the formula, R 1 represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 0 to 3.

[0029] In the formula (1), R 1 is an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms.

[0030] Examples of the compound represented by formula (1) include triphenyl phosphite, tricresyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, trisnonylphenyl phosphite, etc. Among these, tris(2,4-di-t-butylphenyl) phosphite is particularly suitable, and is commercially available as, for example, Irgafos 168 manufactured by BASF ("Irgafos" is a registered trademark of BASF Societas Europea).

[0031] The phosphite-based antioxidant (C) preferably contains, for example, a compound represented by the following formula (2).

[0032] Formula (2): [ka] (In the formula, R 2 , R3 , R 5 and R 6 R 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. 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. Either Y or Z 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.

[0033] In formula (2), 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.

[0034] Here, examples of the alkyl group having 1 to 8 carbon atoms 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 the cycloalkyl group having 5 to 8 carbon atoms include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Examples of the alkylcycloalkyl group having 6 to 12 carbon atoms include 1-methylcyclopentyl, 1-methylcyclohexyl, and 1-methyl-4-i-propylcyclohexyl groups. Examples of the aralkyl group having 7 to 12 carbon atoms include benzyl, α-methylbenzyl, and α,α-dimethylbenzyl groups.

[0035] R 2 , R 3 and R 5 are each preferably independently 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. 2 and R 5 are each 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 is preferably an alkyl group having 1 to 5 carbon atoms, such as 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, and more preferably a methyl group, a t-butyl group, or a t-pentyl group.

[0036] R 6 is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms, and more preferably a hydrogen atom, or an alkyl group having 1 to 5 carbon atoms, such as 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.

[0037] In formula (2), R4 represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include the above-mentioned R 2 , R 3 , R 5 and R 6 In particular, R 4 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.

[0038] In formula (2), X is a single bond, a sulfur atom or a group represented by the formula: -CHR 7 -, where the formula is -CHR 7 -R in 7 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms and the cycloalkyl group having 5 to 8 carbon atoms include the above-mentioned R 2 , R 3 , R 5 and R 6 In particular, X is preferably a single bond, a methylene group, or a methylene group substituted with a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, or the like, and more preferably a single bond.

[0039] In formula (2), A is an alkylene group having 1 to 8 carbon atoms or a group represented by the formula: 8 Examples of the alkylene group having 1 to 8 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, and a 2,2-dimethyl-1,3-propylene group, and the like, with a propylene group being preferred. 8 -R in 8 R represents a single bond or an alkylene group having 1 to 8 carbon atoms. 8 Examples of the alkylene group having 1 to 8 carbon atoms represented by the formula (I) include the alkylene groups exemplified in the description of A above. 8is preferably a single bond or an ethylene group. 8 The * in - is a bond on the oxygen side, indicating that the carbonyl group is bonded to the oxygen atom of the phosphite group.

[0040] In formula (2), one of Y and Z 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. Examples of the alkoxy group having 1 to 8 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, and a pentyloxy group. Examples of the aralkyloxy group having 7 to 12 carbon atoms include a benzyloxy group, an α-methylbenzyloxy group, and an α,α-dimethylbenzyloxy group. Examples of the alkyl group having 1 to 8 carbon atoms include the above-mentioned R 2 , R 3 , R 5 and R 6 Examples of the alkyl group include those exemplified in the explanation of the above.

[0041] Examples of the compound 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]dioxaphosphepine, 6-[3-(3,5-di-t -butyl-4-hydroxyphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepine, 6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-4,8-di-t-butyl-2,10-dimethyl-12H-dibenzo[d,g][1,3,2]dioxaphosphocin, 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]dioxaphosphocin. Among these, when the resulting aromatic polycarbonate resin composition is to be used in fields where optical properties are particularly required, 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosphepine is suitable, and is commercially available, for example, as Sumilizer GP manufactured by Sumitomo Chemical Co., Ltd. ("Sumilizer" is a registered trademark).

[0042] The phosphite-based antioxidant (C) preferably contains, for example, a compound represented by the following formula (3).

[0043] Formula (3): [ka] (In the formula, R 9 and R 10 each independently represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and b and c each independently represent an integer of 0 to 3.

[0044] Examples of the compound represented by formula (3) include bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, etc. Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite is commercially available under the trade name "ADK STAB PEP-24G" manufactured by ADEKA CORPORATION. ADK STAB PEP-36 ("ADK STAB" is a registered trademark) manufactured by ADEKA CORPORATION is commercially available.

[0045] The phosphite-based antioxidant (C) preferably contains, for example, a compound represented by the following formula (3).

[0046] Formula (4): [ka]

[0047] (In the formula, R 11 ~R 18 R each independently represents an alkyl group or an 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 may be bonded to each other to form a ring. 19 ~R 22 are each independently a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. d to g each independently represent an integer of 0 to 5. X 1 ~X 4 Each of X independently represents a single bond or a carbon atom. 1 ~X 4 is a single bond, R 11 ~R 22 Among these, the functional group connected to the single bond is excluded from the general formula (4).

[0048] A specific example of the compound represented by formula (4) is bis(2,4-dicumylphenyl)pentaerythritol diphosphite, which is commercially available under the trade name "Doverphos (registered trademark) S-9228" manufactured by Dover Chemical Co., and under the trade name "ADEKA STAB PEP-45" (bis(2,4-dicumylphenyl)pentaerythritol diphosphite) manufactured by ADEKA Corporation.

[0049] The above-mentioned aromatic polycarbonate resin composition is preferably one that satisfies at least one selected from the following: The phosphite compound represented by formula (1) contains tris(2,4-di-t-butylphenyl)phosphite; The phosphite compound represented by formula (2) contains 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosphepine; The phosphite compound represented by formula (3) contains 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane; and The phosphite compound represented by formula (4) contains bis(2,4-dicumylphenyl)pentaerythritol diphosphite.

[0050] The content of the phosphorous acid-based antioxidant (C) is preferably up to 0.3 parts by weight, and more preferably from 0.01 to 0.1 parts by weight, based on 100 parts by weight of the aromatic polycarbonate resin (A).

[0051] The polycarbonate resin composition pellet according to the present embodiment may contain a small amount of fluorine-based resin (D). As the fluorine resin (D), from the viewpoint of sliding properties, a "non-fibril-forming" one that is not easily fibrous due to external action in a melt-kneaded state is preferable. For example, low molecular weight polytetrafluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-perfluoromethylvinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, etc. are mentioned, among which, from the viewpoint of sliding properties, the use of low molecular weight polytetrafluoroethylene is preferable. The low molecular weight polytetrafluoroethylene also includes one containing a small amount of copolymerization component. As the low molecular weight polytetrafluoroethylene, one that is usually used as a dry lubricant can be used, and is preferably in the form of fine particles. Regarding the particle diameter of the fine particles, the average particle diameter is preferably 1.0 to 20.0 μm, more preferably 3 to 10 μm, and even more preferably 3 to 8 μm, as determined by a method conforming to ASTM D4894.

[0052] The content of the fluorine-based resin (D) is 0.1 parts by weight or less relative to 100 parts by weight of the polycarbonate resin composition (A). In other words, the polycarbonate resin composition pellet according to this embodiment does not contain more than 0.1 parts by weight of the fluorine-based resin (D) relative to 100 parts by weight of the polycarbonate resin composition (A). By making the content of the fluorine-based resin (D) 0.1 parts by weight or less relative to 100 parts by weight of the polycarbonate resin composition (A), it is possible to reduce the fluoride ions derived from the fluorine-based resin (D) and minimize the concentration of fluoride ions eluted from the polycarbonate resin composition pellet into pure water, that is, the eluted fluoride ions.

[0053] Here, the concentration of eluted fluoride ions can be measured by the following method. <Analysis method> The eluted fluoride ion concentration can be determined by placing 30 g of polycarbonate resin composition pellets in 30 mL of pure water at 50° C., holding the pellets for 2 hours to elute fluoride ions, and then cooling the pellets and measuring the concentration by ion chromatography. The concentration of the eluted fluoride ions from the polycarbonate resin composition pellets in the eluate is preferably less than 20 μg / L, more preferably less than 10 μg / L, even more preferably less than 5 μg / L, and most preferably less than 2 μg / L. The market requirement for the eluted fluoride ion concentration from polycarbonate resin composition pellets is approximately less than 20 μg / L.

[0054] When the fluororesin (D) is added, it is preferable to wash the fluororesin (D) in advance with water or a solvent. By washing the fluororesin (D) in advance, the content of fluoride ions in the fluororesin can be reduced, and therefore the concentration of eluted fluoride ions in the obtained polycarbonate resin composition pellets can be reduced.

[0055] The polycarbonate resin composition pellets contain chloride ions derived from phosgene, etc., which is a raw material for the aromatic polycarbonate resin (A), and sulfate ions derived from the catalyst and maleic anhydride-modified ultra-high molecular weight polyethylene (B), etc. These chloride ions and sulfate ions are also impurities, so it is preferable that the content of these ions in the polycarbonate resin composition pellets is reduced as much as possible. Specifically, it is preferable that the chloride ion concentration eluted from the polycarbonate resin composition pellets in pure water at 50°C is less than 15 μg / L, and the sulfate ion concentration is less than 10 μg / L. The chloride ion concentration and sulfate ion concentration eluted in pure water at 50°C can be measured by the same method as the eluted fluoride ion concentration described above.

[0056] The aromatic polycarbonate resin composition pellets according to the present embodiment may contain various additives such as a heat stabilizer, an antioxidant other than a phosphorous acid-based antioxidant, a colorant, a release agent, a softener, an antistatic agent, and an impact modifier, as well as polymers other than the aromatic polycarbonate resin and the maleic anhydride-modified ultra-high molecular weight polyethylene resin, as appropriate, within the scope of not impairing the effects of the present invention.

[0057] The dynamic friction coefficient measured using a flat test piece made from the polycarbonate resin composition pellets according to the present embodiment is preferably less than 0.3, more preferably 0.2 or less. Here, the dynamic friction coefficient is less than 0.5 when a gauze loaded with 200 g is rubbed at a speed of 100 mm / min with a flat indenter of 63.5 mm x 63.5 mm on a flat test piece of 150 mm x 90 mm x 2 mm made by injection molding, and when the dynamic friction coefficient is less than 0.5, when a container member for use in electronic-related parts is molded from the polycarbonate resin composition pellets according to the present embodiment, the required slidability (sliding property) can be satisfied.

[0058] <Manufacturing method of polycarbonate resin pellets> The polycarbonate resin composition pellets according to the present embodiment can be produced, for example, by a production method including a melt-kneading step and a cooling step, which will be described in detail below.

[0059] In the melt-kneading step, polycarbonate resin (A) and maleic anhydride-modified ultra-high molecular weight polyethylene (B) are melt-kneaded in a twin-screw extruder. Phosphite-based antioxidant (C), fluorine-based compound (D), the above-mentioned other additives, and other resins can be blended. Examples of twin-screw extruders include twin-screw extruders such as intermeshing co-rotating twin-screw extruders and multi-screw extruders having two or more screws, with intermeshing co-rotating twin-screw extruders being preferred. The twin-screw extruder is preferably equipped with a hopper, which is a raw material supply port for supplying raw materials, an intermediate supply port, a vent, a jacketed cylinder, a die head, and the like.

[0060] The vent is used to discharge ions, gases, etc. inside the twin-screw extruder, and at least one vent is preferably provided at an appropriate location of 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 degree of the vent pressure is preferably 10 to 30 kPa (-0.091 MPa to -0.071 MPa).

[0061] The kneading temperature in the melt-kneading step is preferably from 230 to 300°C, more preferably from 240 to 280°C.

[0062] In the cooling step, the molten mixture is extruded from a nozzle, and the resulting strand is taken up by a roller and cooled in a pure water bath. In order to obtain pellets with a small amount of eluted fluoride ions in the pellets, the electrical conductivity of the pure water used is preferably 5 μS / cm or less, more preferably 1 μS / cm or less. By using a pure water bath with such electrical conductivity, pellets with a small amount of eluted chloride ions, eluted sulfate ions, etc. other than eluted fluoride ions can be obtained. The water temperature of the pure water bath is preferably about 20 to 80°C. In addition, it is preferable to control the electrical conductivity of the pure water bath so as to keep it constant while circulating it through, for example, a heat exchanger or filter made of a clean material. The concentration of fluoride ions eluted from the obtained polycarbonate resin pellets into the pure water was a low concentration of 9 μg / L. The combination of cooling with a pure water bath and the above-mentioned vent is particularly effective in reducing the fluoride ion concentration in the polycarbonate resin composition pellets.

[0063] After cooling, the strands are cut into pellets using a pelletizer.

[0064] The shape and size of the polycarbonate resin composition pellets are not particularly limited, and may be any shape and size that a typical resin pellet has. For example, the shape of the pellets may be an elliptical cylinder, a cylindrical shape, etc. The pellet size is preferably about 2 to 8 mm in length, and in the case of an elliptical cylinder, the major axis of the cross-sectional ellipse 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 cross-sectional circle is preferably about 1 to 6 mm. Each of the obtained pellets may be of such a size, or all of the pellets forming the pellet aggregate may be of such a size, or the average value of the pellet aggregate may be of such a size, and there is no particular limitation.

[0065] The sliding member for a semiconductor wafer transport container according to the present invention can be obtained by molding the above-mentioned polycarbonate resin composition pellets. The sliding member for a semiconductor wafer transport container is one example of a molded product, and the polycarbonate resin composition pellets according to the present invention can also be used to mold container members for storing electronic-related parts other than semiconductor wafers.

[0066] As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology of the present invention is not limited to these, and can be applied to embodiments in which appropriate changes, substitutions, additions, omissions, etc. are made. EXAMPLES

[0067] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" are based on weight.

[0068] The ingredients used are as follows: 1. Polycarbonate resin (A) Interfacial aromatic polycarbonate resins synthesized from bisphenol A and phosgene. Sumika Polycarbonate Co., Ltd. SD Polyca LE2011-15, viscosity average molecular weight: 20300, phenol concentration 10 ppm or less <Phenol concentration> 1.0 g of polycarbonate pellets was dissolved in 20 mL of dichloromethane, and then 90 mL of methanol was added dropwise to precipitate the polycarbonate resin. The supernatant liquid was then concentrated, and this concentrate was then measured by high performance liquid chromatography.

[0069] 2. Maleic anhydride modified ultra-high molecular weight polyethylene resin (B) Mitsui Chemicals LUBMER (registered trademark) LY1040 (sulfate ions before cleaning: 3000 μg / L, chloride ions: 200 μg / L)

[0070] 3. Phosphite-based antioxidants (C) 3-1. Tris(2,4-di-t-butylphenyl)phosphite, represented by the following formula: [ka] Irgafos 168 (product name) manufactured by BASF, hereinafter also referred to as "C1."

[0071] 3-2. 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: [ka] Adeka STAB PEP-36 (product name) manufactured by ADEKA, hereinafter also referred to as "C2".

[0072] 4. Fluorine-based resin (D) 4-1.Polytetrafluoroethylene INOLUB T212F (product name) manufactured by GFL, hereinafter referred to as "D1" Average particle size: 6.0μm, melting point: approx. 328℃ 4-2.Polytetrafluoroethylene Lubron L-5 (product name) manufactured by Daikin Industries, Ltd., hereinafter referred to as "D2" Average particle size: 4.0μm, melting point: approx. 328℃

[0073] (Examples 1 to 7 and Comparative Examples 1 to 3) A twin-screw extruder (TEK-51MHS manufactured by Japan Steel Works, Ltd.) was used, and the kneading zone temperature was set at 260°C and the screw rotation speed at 400 rpm. From a hopper installed at the most upstream part of the twin-screw extruder, aromatic polycarbonate resin (A), maleic anhydride-modified ultra-high molecular weight polyethylene (B), phosphorous acid-based antioxidant (C) and fluorine-based compound (D) were fed in the ratios shown in Table 1. A strand-shaped molten kneaded material (temperature 263°C) was extruded from the die head through a vent (vacuum degree 20 kPa) on the downstream side of the kneading zone, cooled in a pure water bath (electrical conductivity 1.0 μS / m or less) and pelletized to obtain polycarbonate resin pellets.

[0074] <Kinematic friction coefficient> The obtained resin pellets were dried at 120°C for 4 hours, and then flat test pieces (150mm x 90mm x 2mm) were made using an injection molding machine (ROBOSHOT S2000i100B manufactured by FANUC Corporation) at a set temperature of 300°C and an injection pressure of 65MPa. The dynamic friction coefficient of the obtained test piece was measured when it was rubbed at a speed of 100mm / min with gauze loaded with a 200g load using a flat indenter, and the dynamic friction coefficient of the material was 0.2. A dynamic friction coefficient of less than 0.3 was deemed to have passed the test.

[0075] <Fluoride ion concentration, chloride ion concentration, and sulfate ion concentration eluted from pellets> 30 g of the pellets were placed in 30 mL of pure water at 50°C and held for 3 hours to dissolve, and after cooling, the fluoride ion concentration, chloride ion concentration, and sulfate ion concentration were measured by ion chromatography. The test was deemed to have passed if the amount of eluted fluoride ions was less than 2 μg / L, the amount of eluted chloride ions was less than 15 μg / L, and the amount of eluted sulfate ions was less than 10 μg / L.

[0076] (Evaluation of Charpy notched impact strength) The pellets of each of the resin compositions obtained above were dried at 120°C for 4 hours, and then test pieces were prepared according to the ISO test method using an injection molding machine (ROBOSHOT S2000i100B manufactured by FANUC) at a set temperature of 280°C. The notched Charpy impact strength was measured according to ISO179-1 and ISO75-2 using the test pieces obtained. 2 Passed the above standard, 35KJ / m 2 Anything less than this was considered a failure.

[0077] (Evaluation of initial coloring) After drying the pellets of each of the resin compositions obtained above for 4 hours at 120°C, a flat test piece of 80mm x 50mm x 2mm was prepared using an injection molding machine (ROBOSHOT S2000i100B manufactured by FANUC) at a set temperature of 300°C. Next, the yellowness index (YI) was measured using a spectrophotometer (CMS-35SP manufactured by Murakami Color Research Laboratory) with a D65 light source, a viewing angle of 10°, and a reflection method. A yellowness index (YI) of less than 2 was indicated as ◎, a yellowness index of 2 or more but less than 6 was indicated as ○, and a yellowness index of 6 or more was indicated as ×.

[0078] Tables 1 and 2 show the compositions and evaluation results for each of the examples and comparative examples.

[0079] [Table 1]

[0080] [Table 2]

[0081] In the polycarbonate resin composition pellets according to Examples 1 to 7, the blending ratios of the maleic anhydride-modified ultra-high molecular weight polyethylene resin, the phosphorous-based antioxidant, and the fluororesin were within the above-mentioned ranges, so that the dynamic friction coefficient of the molded product was reduced to less than 0.3, and the concentrations of fluoride ions, chloride ions, and sulfate ions were also extremely low. That is, it was confirmed that the present invention can realize polycarbonate resin composition pellets capable of forming molded products having excellent slip properties and abrasion resistance and containing extremely low amounts of impurity ions such as fluoride ions, chloride ions, and sulfate ions.

[0082] In contrast to this, the polycarbonate resin composition pellets according to Comparative Example 1 had a high dynamic friction coefficient since they did not contain the maleic anhydride modified ultra-high molecular weight polyethylene resin.

[0083] The polycarbonate resin composition pellets according to Comparative Example 2 had a low notched Charpy impact strength and a high yellowness index because the blending amount of maleic anhydride-modified ultra-high molecular weight polyethylene was too high. In addition, the chloride ion and sulfate ion concentrations were high because the chloride ion and sulfate ion derived from the maleic anhydride-modified ultra-high molecular weight polyethylene increased.

[0084] The polycarbonate resin composition pellets according to Comparative Example 3 were prepared by blending a fluororesin instead of the maleic anhydride-modified ultra-high molecular weight polyethylene, and the fluorine ion concentration was increased due to the fluorine ions derived from the fluororesin. The dynamic friction coefficient was also higher than that of the Examples.

[0085] Furthermore, since the above-described embodiment is intended to illustrate the technology of the present invention, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0086] According to the polycarbonate resin composition pellets of the present invention, a molded article made from the pellets has excellent sliding properties and is characterized by an extremely small amount of impurity ions. For example, it can be suitably used as a sliding member for a semiconductor wafer transport container that requires reduced surface contamination, and has high industrial utility value.

Claims

1. A mixture of 100 parts by weight of an aromatic polycarbonate resin (A), 4.0 to 15.0 parts by weight of a maleic anhydride-modified ultra-high molecular weight polyethylene resin (B) and a phosphorous acid-based antioxidant (C ) up to 0.3 parts by weight, and not more than 0.1 parts by weight of fluorine-based resin (D); A polycarbonate resin composition pellet, characterized in that a dynamic friction coefficient of less than 0.3 is observed when a 150 mm x 90 mm x 2 mm flat test piece prepared by injection molding is rubbed with a gauze loaded with a 200 g load using a 63.5 mm x 63.5 mm flat indenter at a speed of 100 mm / min.

2. 2. The polycarbonate resin composition pellet according to claim 1, comprising 0.01 to 0.1 parts by weight of the phosphorous acid-based antioxidant (C).

3. 2. The polycarbonate resin composition pellet according to claim 1, wherein the phosphorous acid-based antioxidant (C) is tris(2,4-di-t-butylphenyl)phosphite or bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite.

4. 2. The polycarbonate resin composition pellet according to claim 1, wherein a concentration of fluoride ions dissolved from the polycarbonate resin composition pellet in pure water at 50° C. is less than 20 μg / L.

5. 2. The polycarbonate resin composition pellet according to claim 1, wherein the fluoride ion concentration eluted from the polycarbonate resin composition pellet in pure water at 50° C. is less than 2 μg / L, the chloride ion concentration is less than 15 μg / L, and the sulfate ion concentration is less than 10 μg / L.

6. The aromatic polycarbonate resin (A) has a viscosity average molecular weight of 18,000 to 23,000; 2. The polycarbonate resin composition pellet according to claim 1, wherein the aromatic polycarbonate resin (A) has a phenol concentration of less than 30 ppm.

7. 6. A sliding member for a semiconductor wafer transport container, which is obtained by molding pellets of the polycarbonate resin composition according to any one of claims 1 to 5.

8. A melt-kneading step of melt-kneading 100 parts by weight of an aromatic polycarbonate resin (A), 4.0 to 15.0 parts by weight of a maleic anhydride-modified ultra-high molecular weight polyethylene resin (B), and up to 0.3 parts by weight of a phosphorous acid-based antioxidant (C) in a twin-screw extruder; a cooling step of extruding the molten mixture from a nozzle and cooling the resulting strand in a pure water bath.