Method for manufacturing polycarbonate resin composition pellets

Abstract

This invention efficiently produces a black polycarbonate resin composition that does not produce aggregates of fluororesin and carbon black, and possesses high Charpy impact strength and high flame retardancy. [Solution] Polycarbonate resin, carbon black, flame retardant masterbatch, fluororesin, and elastomer are supplied to a twin-screw extruder in the following amounts: 100 parts by mass of polycarbonate resin, 0.001 to 3 parts by mass of carbon black, 30 to 70 parts by mass of flame retardant masterbatch, 0.1 to 2 parts by mass of fluororesin, and 2 to 20 parts by mass of elastomer. The aforementioned flame retardant masterbatch is a masterbatch in which the mass ratio of a liquid condensed phosphate ester flame retardant at room temperature to a polycarbonate resin is 30-45:70-55. A method for producing polycarbonate resin composition pellets, characterized in that the value of Ns / Q, obtained by dividing the rotational speed Ns (rpm) of a twin-screw extruder by the discharge rate Q (kg / hr), is between 2 and 5.

Description

[Technical Field]

[0001] The present invention relates to a method for producing polycarbonate resin composition pellets, and more particularly to a method for producing black, flame-retardant polycarbonate resin composition pellets. [Background technology]

[0002] Polycarbonate resin is a resin with excellent heat resistance and mechanical properties, and is therefore widely used as a manufacturing material for parts in various fields, such as electrical equipment, electronic equipment, automobiles and other vehicles, office automation and information equipment such as printers and copiers, housing, construction, and other industrial sectors. These parts require flame retardancy from a safety standpoint to prevent fires caused by high temperatures, and flame-retardant polycarbonate resin compositions are particularly suitable for use in casings of computers, personal computers, various mobile terminals, batteries, and other components.

[0003] Conventionally, a widely known method for imparting flame retardancy to polycarbonate resin is to incorporate halogen-based flame retardants, such as organic bromine compounds, into the polycarbonate resin. However, resin compositions incorporating halogen-based flame retardants may suffer from reduced thermal stability and may cause corrosion of molding machine screws and molds during molding. Furthermore, the inclusion of halogen-based flame retardants may generate halogen-containing gases during combustion, and environmental pollution may become a problem during product disposal and recovery. Therefore, there is a need to achieve flame retardancy without using halogen-based flame retardants.

[0004] Furthermore, Patent Document 1 proposes incorporating phosphorus-based flame retardants into polycarbonate resins instead of halogen-based flame retardants, and currently, phosphorus-based flame retardants are becoming the main type used. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 62-4746 [Overview of the project] [Problems that the invention aims to solve]

[0006] Phosphorus-based flame retardants, such as phosphate ester flame retardants, exist in both solid and liquid forms at room temperature. Liquid forms require liquid addition to the extruder. However, when melt-mixing liquid phosphorus-based flame retardants with polycarbonate resin using an extruder, unmelted polycarbonate resin can be generated, and achieving uniform dispersion of the phosphorus-based flame retardant is difficult, often resulting in insufficient flame retardancy in the resulting polycarbonate resin composition pellets. While using a liquid phosphorus-based flame retardant as a masterbatch is an effective method, it has been found that when manufacturing pellets of a black flame-retardant polycarbonate resin composition containing carbon black, the impact resistance of the resulting molded articles decreases. [Means for solving the problem]

[0007] The inventors conducted extensive analysis to investigate the cause and found that the fluororesin and carbon black blended as flame retardant additives were poorly dispersed, resulting in the formation of aggregates with a particle size of 50 μm or less. Further investigation revealed that polycarbonate resin composition pellets produced by using a liquid condensed phosphate ester flame retardant at room temperature as a masterbatch with polycarbonate resin, and by setting the relationship between the rotational speed Ns (rpm) and discharge rate Q (kg / hr) of a twin-screw extruder within a specific range, could achieve high flame retardancy and a high Charpy impact value, thus completing the present invention. The present invention relates to a method for producing the following polycarbonate resin composition pellets.

[0008] 1. A method for producing pellets of a polycarbonate resin composition using a twin-screw extruder, comprising supplying polycarbonate resin, carbon black, flame retardant masterbatch, fluororesin, and elastomer to the twin-screw extruder, wherein the supply amounts are 0.001 to 3 parts by mass of carbon black, 30 to 70 parts by mass of flame retardant masterbatch, 0.1 to 2 parts by mass of fluororesin, and 2 to 20 parts by mass of elastomer per 100 parts by mass of polycarbonate resin. The aforementioned flame retardant masterbatch is a masterbatch in which the mass ratio of a liquid condensed phosphate ester flame retardant at room temperature to a polycarbonate resin is 30-45:70-55. A method for producing polycarbonate resin composition pellets, characterized in that the value of Ns / Q, obtained by dividing the rotational speed Ns (rpm) of a twin-screw extruder by the discharge rate Q (kg / hr), is between 2 and 5. 2. The manufacturing method according to item 1, wherein the fluororesin is an aqueous dispersion of polytetrafluoroethylene. 3. The manufacturing method according to 1 or 2 above, further comprising supplying 0.01 to 1 part by mass of a phosphorus-based stabilizer and / or a phenol-based stabilizer per 100 parts by mass of polycarbonate resin. [Effects of the Invention]

[0009] The present invention provides a method for producing polycarbonate resin composition pellets that suppresses the generation of aggregates of fluororesin and carbon black, and enables the efficient production of a black flame-retardant polycarbonate resin composition having high Charpy impact strength and high flame retardancy. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below with reference to embodiments and examples, but the present invention is not limited to these embodiments and examples.

[0011] The method for producing polycarbonate resin composition pellets of the present invention is a method for producing pellets of a polycarbonate resin composition using a twin-screw extruder, wherein a polycarbonate resin, carbon black, a flame retardant masterbatch, a fluorine-containing resin and an elastomer are fed into the twin-screw extruder, and the feeding amounts at that time are 0.001 to 3 parts by mass of carbon black, 30 to 70 parts by mass of the flame retardant masterbatch, 0.1 to 2 parts by mass of the fluorine-containing resin, and 2 to 20 parts by mass of the elastomer, relative to 100 parts by mass of the polycarbonate resin, The flame retardant masterbatch is a masterbatch in which the mass ratio of the condensed phosphate ester-based flame retardant that is liquid at room temperature to the polycarbonate resin is 30 to 45:70 to 55, The value of Ns / Q obtained by dividing the rotation speed Ns (rpm) of the twin-screw extruder by the discharge rate Q (kg / hr) is 2 to 5.

[0012] [Polycarbonate resin] Examples of the polycarbonate resin used in the method for producing polycarbonate resin composition pellets of the present invention include aromatic polycarbonate resins, aliphatic polycarbonate resins, and aromatic-aliphatic polycarbonate resins, with aromatic polycarbonate resins being preferred, and specifically, aromatic polycarbonate resins obtained by reacting an aromatic dihydroxy compound with phosgene or a diester of carbonic acid are used.

[0013] Preferable examples of the aromatic dihydroxy compound include 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), 2,2-bis(3-methyl-4-hydroxyphenyl)propane (i.e., bisphenol C), tetramethylbisphenol A, α,α'-bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, and 4,4'-dihydroxydiphenyl.

[0014] Preferable examples of the polycarbonate resin include aromatic polycarbonate resins using bisphenol A as the dihydroxy compound, or a combination of bisphenol A and other aromatic dihydroxy compounds, and aromatic polycarbonate resins using bisphenol C, or a combination of bisphenol C and other aromatic dihydroxy compounds (particularly bisphenol A).

[0015] The polycarbonate resin may be a homopolymer composed of one type of repeating unit, or a copolymer having two or more types of repeating units. At this time, various copolymer forms such as random copolymers and block copolymers can be selected for the copolymer. The method for producing the polycarbonate resin is not particularly limited, and conventional methods such as the phosgene method (interfacial polymerization method) and the melt method (transesterification method) can be used. Further, a polycarbonate resin obtained by subjecting a polycarbonate resin produced by the melt method to a post-treatment for adjusting the amount of terminal OH groups is also preferable.

[0016] The molecular weight of the polycarbonate resin is not limited, but the viscosity average molecular weight (Mv) is usually about 10,000 to 100,000, preferably about 12,000 to 35,000. By setting the viscosity average molecular weight to be equal to or higher than the lower limit of the above range, the mechanical strength of the polycarbonate resin composition can be further improved, which is more preferable when used in applications requiring high mechanical strength. On the other hand, by setting the viscosity average molecular weight to be equal to or lower than the upper limit of the above range, the decrease in fluidity of the polycarbonate resin composition can be suppressed and improved, the molding processability can be enhanced, and thin-wall molding can also be easily performed. Two or more types of polycarbonate resins having different viscosity average molecular weights may be mixed and used. In this case, polycarbonate resins having a viscosity average molecular weight outside the above-mentioned preferred range may be mixed to fall within the above-mentioned molecular weight range.

[0017] In this invention, the viscosity-average molecular weight (Mv) of the polycarbonate resin is calculated using an Ubbelohde viscometer to determine the viscosity of a methylene chloride solution of the polycarbonate resin at 25°C, thereby obtaining the intrinsic viscosity ([η]), and then using Schnell's viscosity formula. [η] = 1.23 × 10 -4 Mv 0.83

[0018] Furthermore, polycarbonate resin produced by the melting method and then subjected to post-treatment to adjust the amount of OH groups at the ends is also preferred.

[0019] The polycarbonate resin may be made from virgin raw materials or from polycarbonate resin recycled from used products (so-called material-recycled polycarbonate resin). It is also preferable to use both virgin raw materials and recycled resin in combination, or to consist solely of recycled polycarbonate resin. When using recycled polycarbonate resin, the proportion of recycled polycarbonate resin in the polycarbonate resin is preferably 40% by mass or more, 50% by mass or more, 60% by mass or more, 80% by mass or more, 90% by mass or more, and may be 100% by mass or more.

[0020] The raw material polycarbonate resin can be in any form, but it is usually in the form of pellets, granules, or flakes. The term "flake" in polycarbonate resin flakes is commonly used in this industry and refers to powder or granular material, including powder, granular, and flake forms.

[0021] [Carbon Black] In the manufacturing method of the present invention, carbon black is supplied. Because the resulting polycarbonate resin composition pellets contain carbon black, the molded product from the pellets can be colored black. There are no restrictions on the manufacturing method or raw material type of carbon black; any conventionally known type, such as oil furnace black, channel black, acetylene black, or Ketjen black, can be used. Among these, oil furnace black is preferred in terms of colorability and cost.

[0022] The average particle size of carbon black can be selected and determined as appropriate, but 5 to 60 nm is preferred, more preferably 7 to 55 nm, and especially preferably 10 to 50 nm. An average particle size of 5 nm or more tends to improve fluidity, while an average particle size of 60 nm or less improves the light-shielding properties of the molded product. The average particle size can be measured using methods such as dynamic light scattering.

[0023] The specific surface area for nitrogen adsorption of carbon black is typically 1000 m². 2 Less than / g is preferable, and among them 50-400m 2 It is preferable that the nitrogen adsorption specific surface area is 1000 m². 2 Setting the nitrogen adsorption specific surface area to less than / g tends to improve the fluidity of the polycarbonate resin composition of the present invention and the appearance of the molded product, which is preferable. The specific surface area of ​​nitrogen adsorption can be measured in accordance with JIS K6217. Furthermore, the DBP absorption capacity of carbon black is 300cm 3 It is preferable that the amount be less than 100g, and especially 30-200cm. 3 It is preferable that the DBP absorption amount is 300 cm³. 3 Using less than 100g tends to improve the fluidity of the polycarbonate resin composition and the appearance of the molded product, which is preferable. Furthermore, DBP absorption can be measured in accordance with JIS K6217.

[0024] Carbon black can be used alone or in combination of two or more types. It can also be granulated using a binder, and it is preferable to use it in the form of a masterbatch in which it is melt-mixed at a high concentration in a resin such as a polystyrene resin.

[0025] The supply amount of carbon black is 0.001 to 3 parts by mass relative to 100 parts by mass of the polycarbonate resin. By supplying in such an amount, pellets of a black, highly light-shielding, flame-retardant polycarbonate resin composition can be obtained. If the amount exceeds 3 parts by mass, the impact resistance of the resin composition decreases significantly, and the heat resistance also deteriorates; if the amount is less than 0.001 parts by mass, the light-shielding property becomes insufficient. The supply amount is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, still more preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more, and is preferably 2.5 parts by mass or less, particularly preferably 2 parts by mass or less.

[0026] [Flame Retardant Masterbatch] In the method for producing polycarbonate resin composition pellets of the present invention, the flame retardant masterbatch is supplied to a twin-screw extruder. As the flame retardant, a condensed phosphate ester-based flame retardant that is liquid at room temperature is used. Here, "liquid at room temperature" means being liquid at 23°C.

[0027] <Condensed Phosphate Ester-Based Flame Retardant> As the condensed phosphate ester, a phosphate ester compound represented by the following general formula (1) that is liquid at room temperature is particularly preferred. [Chemical Formula] (In the formula, R 1 , R 2 , R 3 and R 4 each represent an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms which may be substituted with an alkyl group; p, q, r and s are each 0 or 1, k is an integer of 1 to 5, and X 1 represents an arylene group.)

[0028] The phosphate ester compound represented by the above general formula (1) may be a mixture of compounds having different numbers of k, and in the case of such a mixture of phosphate ester compounds with different k values, k is the average value of those compounds. In the case of a mixture of phosphate ester compounds with different k values, the average k value is preferably 1 to 2, more preferably 1 to 1.5, even more preferably 1 to 1.2, and particularly preferably 1 to 1.15.

[0029] Also, X 1 The arylene group exhibits an arylene group and is a divalent arylene group derived from dihydroxy compounds such as resorcinol, hydroquinone, bisphenol A, 2,2'-dihydroxybiphenyl, 2,3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 1,8-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene. Of these, the divalent arylene group derived from bisphenol A and 3,3'-dihydroxybiphenyl is particularly preferred.

[0030] Furthermore, in general formula (1), p, q, r, and s each represent either 0 or 1, with 1 being preferred. Also, R 1 , R 2 , R 3 and R 4 Each of these represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 20 carbon atoms that may be substituted with an alkyl group. Examples of such aryl groups include phenyl, cresyl, xylyl, isopropylphenyl, butylphenyl, tert-butylphenyl, di-tert-butylphenyl, and p-cumylphenyl groups, but phenyl, cresyl, and xylyl groups are more preferred.

[0031] Among the condensed phosphate esters represented by general formula (1), bisphenol A bisdiphenyl phosphate is a preferred example of a liquid at room temperature. Examples of commercially available products include "CR-741" manufactured by Daihachi Chemical Industry Co., Ltd. and "ADEKA Stab FP-600" manufactured by ADEKA Corporation.

[0032] In the manufacturing method of the present invention, a condensed phosphate ester flame retardant that is liquid at room temperature is supplied in the form of a flame retardant masterbatch with a polycarbonate resin. The masterbatch used has a mass ratio of 30-45:70-55 between the condensed phosphate ester flame retardant that is liquid at room temperature and the polycarbonate resin. Having a mass ratio of 30-45:70-55 between the condensed phosphate ester flame retardant that is liquid at room temperature and the polycarbonate resin is within this range prevents the condensed phosphate ester flame retardant that is liquid at room temperature from becoming unevenly distributed or localized within the polycarbonate resin, resulting in a good flame retardant effect.

[0033] The method for producing a flame retardant masterbatch is not particularly limited, but it is preferable to supply a polycarbonate resin to a twin-screw extruder, and after the polycarbonate resin is melted in the kneading section of the extruder, a condensed phosphate ester flame retardant that is liquid at room temperature is supplied in the amount specified above in the mass ratio, and the polycarbonate resin and the condensed phosphate ester flame retardant that is liquid at room temperature are melt-kneaded in the kneading section downstream of the extruder.

[0034] The flame retardant masterbatch preferably contains a stabilizer, and the stabilizer content is preferably 0 to 0.1% by mass of the flame retardant masterbatch. A stabilizer content exceeding 0.1% by mass is undesirable because it tends to worsen the hue. Phosphorus-based stabilizers and / or phenol-based stabilizers are preferred as stabilizers. Furthermore, while it is preferable to include the stabilizer in the flame retardant masterbatch, it is also preferable to supply it into the twin-screw extruder, as with other raw materials, as described later.

[0035] The amount of flame retardant masterbatch supplied to the twin-screw extruder is 30 to 70 parts by mass, preferably 35 to 60 parts by mass, and more preferably 40 to 50 parts by mass, per 100 parts by mass of polycarbonate resin.

[0036] [Fluorine resin] In the method for producing polycarbonate resin composition pellets of the present invention, a fluororesin is supplied. By supplying the fluororesin together with each component, the melting properties of the resin composition can be improved, thereby improving drip prevention during combustion and further enhancing flame retardancy. As the fluororesin, fluoroolefin resins are preferred. Fluoroolefin resins are typically polymers or copolymers containing a fluoroethylene structure. Specific examples include difluoroethylene resins, tetrafluoroethylene resins, and tetrafluoroethylene / hexafluoropropylene copolymer resins, but tetrafluoroethylene resins are preferred among these.

[0037] Furthermore, as the fluororesin, one that has fibril-forming ability is preferred, and a specific example is a fluoroolefin resin that has fibril-forming ability. In this way, having fibril-forming ability tends to significantly improve the ability to prevent dripping during combustion. Furthermore, an aqueous dispersion of fluororesin, commonly known as a dispersion type, in which fluororesin is uniformly dispersed in an aqueous solution, is preferable because it allows for more uniform dispersion of the fluororesin component within the polycarbonate resin.

[0038] Furthermore, fluororesins coated with organic polymers can also be suitably used as fluororesins. Using organic polymer-coated fluororesins is preferable because it improves dispersibility, enhances the surface appearance of the molded product, and suppresses surface aggregates.

[0039] Organic polymer-coated fluororesins can be produced by various known methods, including (1) a method of producing them by mixing an aqueous dispersion of polyfluoroethylene particles and an aqueous dispersion of organic polymer particles and then pulverizing them by coagulation or spray drying; (2) a method of producing them by polymerizing monomers constituting an organic polymer in the presence of an aqueous dispersion of polyfluoroethylene particles, and then pulverizing them by coagulation or spray drying; and (3) a method of producing them by emulsion polymerization of monomers having ethylenically unsaturated bonds in a dispersion obtained by mixing an aqueous dispersion of polyfluoroethylene particles and an aqueous dispersion of organic polymer particles, and then pulverizing them by coagulation or spray drying. For producing organic polymers that coat fluoroolefin resins and other fluorine-containing resins, monomers with high affinity to polycarbonate resins are preferred from the viewpoint of dispersibility when blended with polycarbonate resins. Examples include aromatic vinyl monomers, (meth)acrylic acid ester monomers, and vinyl cyanide monomers.

[0040] One type of fluororesin may be used, or two or more types may be used in any combination and ratio.

[0041] The amount of fluororesin supplied is 0.1 to 2 parts by mass per 100 parts by mass of polycarbonate resin. By supplying fluororesin in this amount, the flame retardancy properties of the molded articles of the resulting polycarbonate resin composition pellets can be further improved. If the amount of fluororesin supplied is less than 0.1 parts by mass, the flame retardancy improvement effect of the fluororesin tends to be insufficient, and if it exceeds 2 parts by mass, poor appearance and reduced mechanical strength of the molded polycarbonate resin composition pellets tend to occur. The amount supplied is preferably 0.15 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 1.5 parts by mass or less, and more preferably 1 part by mass or less. When the fluororesin is used in the form of an aqueous dispersion, the amount of fluororesin should be within the above range.

[0042] [Elastomer] In the manufacturing method of the present invention, the elastomer is supplied to a twin-screw extruder. As the elastomer, copolymers obtained by graft copolymerizing a rubber component with a monomer component that can copolymerize with it are preferred. Among such elastomers, core-shell type elastomers are preferred.

[0043] As a core-shell type elastomer, a core-shell type graft copolymer is preferred, which consists of a rubbery polymer as the core layer and a shell layer formed around it by copolymerizing monomer components such as acrylic acid esters, methacrylic acid esters, and aromatic vinyl compounds.

[0044] As the core layer of the rubbery polymer, it is preferable to use at least one rubbery polymer selected from butadiene copolymer rubber, butyl acrylate copolymer rubber, 2-ethylhexyl acrylate copolymer rubber, and silicone rubber as the core layer. The rubbery polymer component is preferably one with a glass transition temperature of 0°C or lower, more preferably -20°C or lower, and even more preferably -30°C or lower.

[0045] As a core-shell type elastomer, a graft copolymer is preferred, which is obtained by graft polymerization of a monomer component copolymerizable with a diene-based rubber component. Such a graft copolymer may be manufactured using any of the following methods: bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, and the copolymerization method may be single-stage grafting or multi-stage grafting.

[0046] Specific examples of diene-based rubber components include polybutadiene rubber, butadiene-acrylic composite rubber, styrene-butadiene rubber, and ethylene-propylene-butadiene rubber. These may be used individually or in combination of two or more.

[0047] Specific examples of monomer components that can be graft copolymerized with rubber components include aromatic vinyl compounds, vinyl cyanide compounds, (meth)acrylic acid ester compounds, epoxy group-containing (meth)acrylic acid ester compounds such as glycidyl (meth)acrylate; maleimide compounds such as maleimide, N-methylmaleimide, and N-phenylmaleimide; and α,β-unsaturated carboxylic acid compounds such as maleic acid, phthalic acid, and itaconic acid, and their anhydrides (e.g., maleic anhydride). These monomer components may be used individually or in combination of two or more. Among these, aromatic vinyl compounds, vinyl cyanide compounds, (meth)acrylic acid ester compounds, and (meth)acrylic acid compounds are preferred in terms of mechanical properties and surface appearance, and (meth)acrylic acid ester compounds are more preferred. Specific examples of (meth)acrylic acid ester compounds include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, and octyl (meth)acrylate. Here, "(meth)acrylic" refers to either "acrylic" or "methacrylic," or both. The same applies to "(meth)acrylate."

[0048] The core-shell type elastomer is preferably a butadiene-based elastomer. Among these, a core-shell type graft copolymer consisting of a polybutadiene-based rubber component as the core layer is preferred, and a shell layer formed by copolymerizing (meth)acrylic acid ester around the core layer is particularly preferred. In the above core-shell type graft copolymer, it is preferable that the butadiene-based rubber component is contained in 40% by mass or more, and more preferably 60% by mass or more. Furthermore, it is preferable that the (meth)acrylic acid ester component is contained in 10% by mass or more.

[0049] Preferred specific examples of these core-shell type graft copolymers include methyl methacrylate-butadiene-styrene copolymer (MBS), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS), methyl methacrylate-butadiene copolymer (MB), methyl methacrylate-acrylic-butadiene rubber copolymer, and methyl methacrylate-acrylic-butadiene rubber-styrene copolymer. Such rubbery polymers may be used individually or in combination of two or more.

[0050] The amount of elastomer supplied is 2 to 20 parts by mass per 100 parts by mass of polycarbonate resin, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. If the supply amount exceeds 20 parts by mass, it is likely to cause a decrease in heat resistance and a deterioration in the flame retardancy of the polycarbonate resin composition.

[0051] [Phosphorus-based stabilizers and / or phenol-based stabilizers] In the method for producing polycarbonate resin composition pellets of the present invention, it is also preferable to supply and incorporate a phosphorus-based stabilizer and / or a phenol-based stabilizer.

[0052] As a phosphorus-based stabilizer, any known phosphorus compound other than the condensed phosphate esters that are liquid at room temperature as described above can be used. Specifically, examples include phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, polyphosphate and other phosphorus oxoacids; acidic pyrophosphate metal salts such as sodium acidic pyrophosphate, potassium acidic pyrophosphate, and calcium acidic pyrophosphate; phosphates of group 1 or group 2 metals such as potassium phosphate, sodium phosphate, cesium phosphate, and zinc phosphate; and organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds, but organic phosphite compounds are particularly preferred.

[0053] Examples of organic phosphite compounds include triphenyl phosphite, tris(mononylphenyl) phosphite, tris(mononyl / dinonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, monooctyldiphenyl phosphite, dioctylmonophenyl phosphite, monodecyldiphenyl phosphite, didecylmonophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, and bis(2,4-di-t-butylphenyl)pentaerythritol-diphosphite. Examples of such organic phosphite compounds include, for example, "ADEKA Stab 1178," "ADEKA Stab 2112," "ADEKA Stab HP-10," and "ADEKA Stab PEP-36" from ADEKA Corporation, "JP-351," "JP-360," and "JP-3CP" from Johoku Chemical Industry Co., Ltd., and "Irgaphos 168" from BASF. Furthermore, phosphorus-based stabilizers may be supplied as a single agent, or as two or more agents in any combination and ratio.

[0054] Examples of phenolic stabilizers include hindered phenolic antioxidants. Specific examples include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 2,4-dimethyl-6-(1-methylpentadecyl)phenol, diethyl[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphoate, 3,3',3”,5,5',5”-hexa-tert-butyl-a,a',a”-(mesitylene-2,4,6- Examples include triyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, ethylenebis(oxyethylene)bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-ylamino)phenol, and 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate.

[0055] Among these, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are preferred. Specific examples of such phenolic antioxidants include BASF's "Irganox 1010" and "Irganox 1076," and ADEKA's "ADEKA Stab AO-50" and "ADEKA Stab AO-60." Furthermore, the phenolic stabilizer may be supplied as a single agent, or as two or more agents in any combination and ratio.

[0056] The amount of phosphorus-based stabilizer supplied is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, per 100 parts by mass of polycarbonate resin, and usually 1 part by mass or less, preferably 0.7 parts by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.1 parts by mass or less. If the amount of phosphorus-based stabilizer supplied is below the lower limit of the above range, the thermal stabilization effect may be insufficient, and if the amount of phosphorus-based stabilizer supplied exceeds the upper limit of the above range, the effect may plateau and become uneconomical.

[0057] The amount of phenolic stabilizer supplied is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and usually 1 part by mass or less, preferably 0.5 parts by mass or less, and more preferably 0.2 parts by mass or less, per 100 parts by mass of polycarbonate resin. By supplying the amount of phenolic stabilizer above the lower limit of the above range, the effect of the phenolic stabilizer can be sufficiently obtained. Furthermore, by supplying the amount of phenolic stabilizer below the upper limit of the above range, the effect does not plateau, making it economical.

[0058] The total amount supplied of phosphorus-based stabilizers and phenol-based stabilizers is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and usually 1 part by mass or less, preferably 0.7 parts by mass or less, and more preferably 0.5 parts by mass or less, per 100 parts by mass of polycarbonate resin.

[0059] [Additives, etc.] In the method for producing polycarbonate resin composition pellets of the present invention, other additives besides those mentioned above can be supplied, such as mold release agents, ultraviolet absorbers, fluorescent whitening agents, pigments other than carbon black, dyes, antistatic agents, antifogging agents, fillers, antiblocking agents, flow improvers, plasticizers, dispersants, antibacterial agents, and compatibilizers. These additives may be supplied individually, or two or more may be supplied in any combination and ratio.

[0060] In addition, other resins besides polycarbonate resin may be supplied. Examples of other resins include thermoplastic polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate; styrene-based resins such as acrylonitrile-butadiene-styrene copolymer (ABS resin), polystyrene resin (GPPS), high-impact polystyrene resin (HIPS), and acrylonitrile-styrene copolymer (AS resin); polyolefin resins such as polyethylene resin and polypropylene resin; polyamide resin; polyimide resin; polyetherimide resin; polyurethane resin; polyphenylene ether resin; polyphenylene sulfide resin; polysulfone resin; and polymethacrylate resin. Furthermore, other resins may be supplied individually, or two or more types may be supplied in any combination and ratio. When supplying resins other than polycarbonate resin, the amount supplied is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, per 100 parts by mass of polycarbonate resin.

[0061] [Manufacturing of polycarbonate resin composition pellets] The present invention provides a method for producing polycarbonate resin composition pellets, comprising supplying polycarbonate resin, carbon black, flame retardant masterbatch, fluororesin, elastomer, and other components supplied as needed, in predetermined amounts to a twin-screw extruder, and setting the value of Ns / Q, obtained by dividing the rotational speed (also called screw rotational speed) Ns (rpm) of the twin-screw extruder by the discharge rate Q (kg / hr), to 2 to 5.

[0062] By keeping the Ns / Q value within this range, the decrease in impact resistance due to the incorporation of carbon black can be suppressed, and the condensed phosphate ester flame retardant can be homogeneously dispersed in the resin composition, enabling the stable expression of high flame retardancy. If the Ns / Q value falls below 2, minute aggregates remain due to poor dispersion of fluororesins such as PTFE and carbon black, resulting in reduced impact resistance and an appearance with many white spot aggregates. On the other hand, if it exceeds 5, the resin may decompose due to abnormally high shear heat generation, or the extruder may malfunction due to overload caused by excessively high rotation speeds, or production volume may be reduced due to reduced discharge rate. The rotational speed is preferably 350 to 700 rpm, and the discharge rate is preferably 130 to 350 kg / hr.

[0063] Various types of twin-screw extruders can be used, and the screw rotation method can be either co-direction or counter-direction, but a co-direction meshing twin-screw extruder is preferred. The length, diameter, meshing ratio, etc. of the twin-screw extruder screws can be any size or set as desired. In addition, the twin-screw extruder may be equipped with a vent that is either reduced in pressure or open to the atmosphere.

[0064] The polycarbonate resin and other components mentioned above are supplied to the extruder from the supply port at the base of the twin-screw extruder. The extruder barrel is heated and the screw rotates, causing the materials to melt and knead in the mixing section as they are carried towards the discharge port. After the discharged strands have cooled, they are cut into pellets in a granulator (pelletizer).

[0065] The screw configuration of the kneading section is preferably a combination of a forward-feeding kneading disc (R) and an orthogonal-feeding kneading disc (N) or a reverse-feeding kneading disc (L).

[0066] [Polycarbonate resin composition] The content of each of the above-mentioned components in the polycarbonate resin composition pellets obtained by the method of the present invention is preferably 0.001 to 3 parts by mass of carbon black, 7 to 23 parts by mass of condensed phosphate ester flame retardant, 0.1 to 2 parts by mass of fluororesin, and 2 to 20 parts by mass of elastomer per 100 parts by mass of polycarbonate resin.

[0067] The polycarbonate resin composition pellets obtained by the method of the present invention, when molded to a thickness of 0.8 mm and tested in accordance with UL94, can achieve a high flame retardancy of V-0. Furthermore, they can achieve a high Charpy impact strength; specifically, the notched Charpy impact strength measured according to ISO179 is preferably 40 kJ / m². 2 That is all. 45 kJ / m³ 2 It is more preferable that the above conditions are met. The notched Charpy impact strength described above is measured according to the example described below.

[0068] [Polycarbonate resin molded product] The method for manufacturing molded products from polycarbonate resin composition pellets is not particularly limited, and any molding method commonly used for polycarbonate resin can be employed, namely general injection molding, ultra-high-speed injection molding, injection compression molding, multi-color injection molding, gas-assisted injection molding, molding using a heat-insulating mold, molding using a rapidly heated and cooled mold, foam molding (including foam molding using supercritical fluid), insert molding, IMC (in-mold coating) molding, extrusion molding, sheet molding, thermoforming, rotational molding, lamination molding, and press molding. Furthermore, for various injection molding methods, a molding method using a hot runner system can also be selected.

[0069] The resulting molded products can be suitably used as electrical equipment, electronic equipment, vehicles such as automobiles, office automation and information equipment such as printers and copiers, housing, buildings, and other parts. In particular, they can be suitably used as housings for computers, personal computers, various mobile terminals, batteries, etc. [Examples]

[0070] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples. The raw material components used in the examples and comparative examples are shown in Table 1 below.

[0071] [Table 1]

[0072] The flame retardant masterbatch in the table above was manufactured using the following manufacturing example 1. (Manufacturing Example 1) Polycarbonate resin "S-3000" was supplied at 130 kg / hr to a twin-screw extruder (manufactured by Japan Steel Works, Ltd., TEX44αII, maximum rotation speed 733 rpm), and melt-kneaded in the first kneading section (RRNNL: the uppermost R is 1.0D in length, the other RNNLs are each 0.5D, D (screw diameter) = 44 mm). Downstream, liquid condensed phosphate ester flame retardant "Adekastab FP-600" at room temperature was supplied at 70 kg / hr and kneaded with the polycarbonate resin in the second kneading section downstream (RNL: each 0.5D in length). The mixture was extruded from the die nozzle, cooled in a water bath, and pelletized to obtain a masterbatch pellet with a concentration of 35% by mass of the condensed phosphate ester flame retardant (mass ratio of condensed phosphate ester flame retardant to polycarbonate resin of 35:65). The screw rotation speed was set to 700 rpm. R is a forward-feed kneading disc with 5 paddles, N is an orthogonal-feed kneading disc with 5 paddles, and L is a reverse-feed kneading disc with 5 paddles. The cylinder temperature was set to 240°C and the die temperature to 280°C.

[0073] (Examples 1-6, Comparative Examples 1-6) Each component listed in Table 1 was mixed in the proportions (parts by mass) listed in Tables 2 and below in a tumbler for 20 minutes. The mixture was then supplied at 170 kg / hr to the base hopper of a twin-screw extruder TEX44αII. The mixture was melt-kneaded in the kneading section (RRRNL: the uppermost R is 1.0D in length, the other RRNL are each 0.5D, D (screw diameter) = 44 mm) at the screw rotation speed (rpm) listed in Tables 2 and below. The mixture was then extruded from the die nozzle at the discharge rate (kg / h) listed in Tables 2 and below. After cooling in a water tank, the strands were cut in a pelletizer to obtain pellets of the polycarbonate resin composition. The cylinder temperature was 260°C and the die temperature was 260°C.

[0074] (Comparative Example 7) Each component listed in Table 1, excluding the liquid condensed phosphate ester flame retardant (Adekastab FP-600) at room temperature, was mixed in a tumbler for 20 minutes in the proportions (parts by mass) listed in Table 3. This mixture was then supplied at 153 kg / hr to the base hopper of a twin-screw extruder TEX44αII. Next, Adekastab FP-600 was added at 17 kg / hr in the proportions (parts by mass) listed in Table 3, between the base hopper and the kneading section (screw configuration is the same as in Example 1). The mixture was melt-kneaded at the screw rotation speed (rpm) listed in Table 3, extruded from the die nozzle at the discharge rate (kg / h) listed in Table 3, cooled in a water tank, and the strands were cut in a pelletizer to obtain pellets of the polycarbonate resin composition. The cylinder temperature was 260°C and the die temperature was 260°C.

[0075] [Flame retardancy evaluation: UL94 test] The polycarbonate resin composition pellets obtained above were dried at 120°C for 4 hours, and then UL test specimens with a thickness of 0.8 mm were obtained using an injection molding machine (Sumitomo Heavy Industries, Ltd. "SE100DU") under conditions of a resin composition temperature of 280°C and a mold temperature of 80°C. The obtained UL test specimens were conditioned for 48 hours in a high-temperature chamber at 23°C and 50% relative humidity, and then subjected to a vertical combustion test in accordance with the UL94 test (combustion test for plastic materials for equipment components) established by Underwriters Laboratories (UL) in the United States, to evaluate the flammability results. The evaluation results are ranked from best to worst as V-0, V-1, and V-2.

[0076] [Measurement of Charpy impact strength (with notch)] The polycarbonate resin composition pellets obtained above were dried at 120°C for 5 hours, and then 3 mm thick ISO dumbbell test pieces were molded using an injection molding machine (NEX80, manufactured by Nissei Plastic Industrial Co., Ltd.) under the following conditions: cylinder temperature 280°C, mold temperature 100°C, injection speed 30 mm / s, and holding pressure 90 MPa. Using the ISO dumbbell test specimens (3 mm thick) obtained above, the notched Charpy impact strength (unit: kJ / m²) was measured in accordance with ISO 179. 2 ) was measured. The evaluation results are shown in Table 2-3 below.

[0077] [Table 2]

[0078] [Table 3] [Industrial applicability]

[0079] According to the present invention, by suppressing the formation of aggregates of fluororesin and carbon black, a black polycarbonate resin composition having high Charpy impact strength and high flame retardancy can be efficiently produced.

Claims

1. A method for producing pellets of a polycarbonate resin composition using a twin-screw extruder, comprising supplying polycarbonate resin, carbon black, flame retardant masterbatch, fluororesin, and elastomer to the twin-screw extruder, wherein the supply amounts are 0.001 to 3 parts by mass of carbon black, 30 to 70 parts by mass of flame retardant masterbatch, 0.1 to 2 parts by mass of fluororesin, and 2 to 20 parts by mass of elastomer per 100 parts by mass of polycarbonate resin. The aforementioned flame retardant masterbatch is a masterbatch in which the mass ratio of a liquid condensed phosphate ester flame retardant at room temperature to a polycarbonate resin is 30 to 45:70 to 55. A method for producing polycarbonate resin composition pellets, characterized in that the value of Ns / Q, obtained by dividing the rotational speed Ns (rpm) of a twin-screw extruder by the discharge rate Q (kg / hr), is between 2 and 5.

2. The manufacturing method according to claim 1, wherein the fluorine-containing resin is an aqueous dispersion of polytetrafluoroethylene.

3. Furthermore, the manufacturing method according to claim 1 or 2, wherein 0.01 to 1 part by mass of a phosphorus-based stabilizer and / or a phenol-based stabilizer is supplied per 100 parts by mass of polycarbonate resin.

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