Method for producing flame-retardant polycarbonate resin composition pellets

Abstract

To provide a method for producing polycarbonate resin composition pellets which are uniform and excellent in flame retardancy and hue.SOLUTION: There is provided a method for producing flame-retardant polycarbonate resin composition pellets which are composed of: 30 to 85 mass% of resin pellets (A) containing more than 40 mass% of a polycarbonate resin having Mw / Mn of 2.7 to 3.4; 5 mass% or more and less than 25 mass% of a phosphorus-based flame retardant (B); 0.1 to 1.0 mass% of polytetrafluoroethylene (C); 0 to 50 mass% of polycarbonate resin flakes (D); 0 to 30 mass% of an ABS resin (E); and 0 to 15 mass% of an additive (F) other than additives (B) and (C) based on the 100 mass% of the materials (A) to (F). The method for producing flame-retardant polycarbonate resin composition pellets comprises: putting the materials (A), (C), (D), (E) and (F) into a twin-screw extruder; kneading a resulting material at a first kneading section; adding the material (B) at a downstream section of the first kneading section and kneading the resulting material at a second kneading section; and then extruding a kneaded material in a strand-shape from the twin-screw extruder; and cutting an extruded material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing flame-retardant polycarbonate resin composition pellets.

Background Art

[0002] Since polycarbonate resin is a resin excellent in heat resistance and mechanical properties, it is widely used, for example, as a material for manufacturing parts in various fields such as vehicles such as electric appliances, electronic devices, automobiles, OA devices such as printers and copiers, houses, buildings, and other industrial fields. These products are required to have flame retardancy from the viewpoint of safety for preventing fires caused by high temperatures. In particular, flame-retardant polycarbonate resin compositions are suitably used as housings for OA devices such as printers and copiers, personal computers, various portable terminals, batteries, and the like.

[0003] On the other hand, in recent years, due to the increasing awareness of environmental protection, recycling of resins has been strongly demanded socially, and regulations are also being strengthened by various laws and regulations. In particular, there is a requirement for the use of recycled resins for the exteriors and housings of OA devices and electronic devices, etc., and there are an increasing number of cases where a polycarbonate resin composition containing a predetermined amount of recycled resin is required.

[0004] In order to recycle thermoplastic plastics from used products, for example, as described in Patent Document 1, the thermoplastic plastic members recovered from equipment parts are pulverized, washed with a cleaning liquid, and the thermoplastic plastic pulverized matter is separated from the pulverized mixture.

[0005] Examples of raw materials for recycled materials of polycarbonate resin include optical disks such as CDs and DVDs, light guide plates, vehicle transparent members such as automotive window glass and automotive headlamp lenses, windshields, containers such as water bottles, spectacle lenses, building members such as soundproof walls and glass windows, corrugated sheets, etc. Pellets obtained by pulverizing, washing, separating, and recovering these are used. Also, by-products such as sprues and runners during molding are repelletized and used.

[0006] In order to particularly employ such recycled materials in OA equipment and the like, high flame retardancy is required. As a means for imparting flame retardancy to polycarbonate resin, conventionally, a method of blending a halogen-based flame retardant such as an organic bromine compound with polycarbonate resin has been widely known. In recent years, however, it has been proposed to blend a halogen-based flame retardant and a phosphorus-based flame retardant with polycarbonate resin, and currently, phosphorus-based flame retardants are becoming the mainstay.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] Phosphorus-based flame retardants, particularly phosphate ester-based flame retardants and the like, have a low melting temperature. When melt-kneaded with polycarbonate resin pellets or resin pellets containing polycarbonate resin, it is difficult for the phosphorus-based flame retardant to mix with the pellets, and unmelted materials of the polycarbonate resin pellets or resin pellets containing polycarbonate resin are likely to occur. This is because the melted phosphorus-based flame retardant acts as a lubricant, weakening the force such as shear applied to the pellets from the extruder. As a result, it is easy for venting to occur at the vent opening, the discharge amount not to increase, the strand not to be taken up, and the flame retardancy of the obtained polycarbonate resin composition pellets to be insufficient, and the impact strength is likely to decrease due to heat retention during molding. An object (problem) of the present invention is to provide a method for producing flame-retardant polycarbonate resin pellets that solves the above problems.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above problems, the inventors of the present invention added a phosphorus-based flame retardant and polytetrafluoroethylene to resin pellets containing a polycarbonate resin having a molecular weight distribution within a specific range, and when producing them with a twin-screw extruder, kneaded them in a specific kneading section, and found that no generation of unmelted matter or vent-up occurred, and excellent polycarbonate resin composition pellets with stable productivity at a high discharge rate, uniform and excellent flame retardancy, and excellent impact strength that hardly decreases even when heat is retained can be produced, thus completing the present invention. The present invention relates to a method for producing the following flame-retardant polycarbonate resin composition pellets.

[0010] [1] A method for producing flame-retardant polycarbonate resin composition pellets consisting of 30 to 85% by mass of resin pellets (A) containing more than 40% by mass of a polycarbonate resin having Mw / Mn of 2.7 to 3.4 in the pellets, 5% by mass or more and less than 25% by mass of a phosphorus-based flame retardant (B), 0.1 to 1.0% by mass of polytetrafluoroethylene (C), 0 to 50% by mass of polycarbonate resin flakes (D), 0 to 30% by mass of an ABS resin (E), and 0 to 15% by mass of other additives (F) other than (B) and (C) [however, the total of (A) to (F) is 100% by mass], using a twin-screw extruder, putting the above (A), (C), (D), (E) and (F) into a twin-screw extruder, including a first step of kneading in a first kneading section and a second step of adding the (B) to a downstream portion of the first kneading section and kneading in a second kneading section, the first kneading section being composed of a configuration having a length of 1.5D to 6.5D (D is the barrel diameter) in which two or more of an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, a mixing screw, or a rotor screw are combined, the second kneading section being composed of a configuration having a length of 1.3D to 6.5D (D is the barrel diameter) in which two or more of an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, a mixing screw, or a rotor screw are combined, A method for producing flame-retardant polycarbonate resin pellets, characterized by extruding strands from a twin-screw extruder and cutting them after the second step. [2] The production method according to [1] above, wherein the average weight of the resin pellets (A) is 13 to 35 mg / piece. [3] The production method according to [1] or [2] above, wherein the resin pellets (A) are recycled pellets. [4] The production method according to any one of [1] to [3] above, wherein the phosphorus-based flame retardant (B) is a condensed phosphate ester compound. [5] The production method according to any one of [1] to [4] above, wherein the phosphorus-based flame retardant (B) is a condensed phosphate ester compound that is liquid at room temperature.

Advantages of the Invention

[0011] According to the production method of the present invention, a polycarbonate resin having a wide molecular weight distribution with Mw / Mn of 2.7 to 3.4 is kneaded by a screw having a specific configuration, so that a polycarbonate resin composition pellet with high discharge amount, stable productivity, uniform and excellent flame retardancy, and difficult to reduce impact strength even when heat is retained can be produced. A polycarbonate resin having a wide molecular weight distribution with Mw / Mn of 2.7 to 3.4 is likely to have an increased viscosity in the low shear rate region. This is considered to be because the entanglement of the polycarbonate polymer chains of the high molecular weight component is difficult to unravel and stress relaxation does not proceed. Therefore, it is considered that dripping during combustion is suppressed and the flame retardancy is improved. In addition, when producing a polycarbonate resin having a wide molecular weight distribution as described above, it is necessary to apply a heat history to the polycarbonate resin or melt-knead a high molecular weight polycarbonate and a low molecular weight polycarbonate. However, when melt-kneading a high molecular weight polycarbonate and a low molecular weight polycarbonate, the viscosity difference between the two is large, and strong kneading is required to uniformly melt-knead them, and the temperature during kneading is also likely to rise. As a result, the high molecular weight polycarbonate is easily damaged. It is considered that the impact strength of the retention molding is likely to decrease due to this, but according to the method of the present invention, the impact strength of the retention molding can be achieved at a high level.

Brief Description of the Drawings

[0012]

Figure 1

Mode for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not construed as being limited to such embodiments and examples.

[0014] The raw materials used in the method for producing the polycarbonate resin composition pellets of the present invention are, based on a total of 100% by mass of (A) to (F), 30 to 85% by mass of resin pellets (A) containing more than 40% by mass of a polycarbonate resin having an Mw / Mn of 2.7 to 3.4 in the pellets, 5% by mass or more and less than 25% by mass of a phosphorus-based flame retardant (B), 0.1 to 1.0% by mass of polytetrafluoroethylene (C), 0 to 50% by mass of polycarbonate resin flakes (D), 0 to 30% by mass of an ABS resin (E), and 0 to 15% by mass of other additives (F) other than (B) and (C).

[0015] [Resin Pellets (A)] The method for producing the polycarbonate resin composition pellets of the present invention uses resin pellets (A) containing more than 40% by mass of a polycarbonate resin having an Mw / Mn of 2.7 to 3.4 in the pellets. As the resin pellet (A), a polycarbonate resin having an Mw / Mn in the range of 2.7 to 3.4 may be contained in an amount of more than 40% by mass as the resin pellet (A). A mixture or alloy containing other resins or the like in addition to the polycarbonate resin can also be preferably used. The resin pellet (A) containing more than 40% by mass of the polycarbonate resin having an Mw / Mn of 2.7 to 3.4 in the pellet is a resin pellet composed of the polycarbonate resin having the above molecular weight distribution and, for example, a resin or additive incompatible therewith. Specifically, it is preferably a resin pellet composed of a polycarbonate resin and an ABS resin, an AS resin, a polystyrene-based resin, a polyolefin resin, an elastomer incompatible with the polycarbonate resin, a filler, etc., and contains more than 40% by mass of the polycarbonate resin having an Mw / Mn of 2.7 to 3.4. Naturally, the polycarbonate resin itself (i.e., 100% by mass) may be used. In the resin pellet (A), the polycarbonate resin pellet having an Mw / Mn of 2.7 to 3.4 is preferably more than 50% by mass.

[0016] The measurement of Mw / Mn of the resin pellet (A) is determined in terms of polystyrene by GPC. The details of the measurement method are as described in detail in the examples.

[0017] The Mw / Mn of the resin pellet (A) is preferably 2.7 or more, more preferably 2.8 or more, preferably 3.4 or less, and more preferably 3.3 or less.

[0018] Here, the pellet referred to is one that has been once melted and uniformly formed into granules. The preferred average weight of the resin pellet (A) is in the range of 10 to 40 mg / piece, preferably 13 to 35 mg / piece, and more preferably 15 to 30 mg / piece. If the average weight is small, melting in the extruder is accelerated, the resin temperature tends to increase, and the polycarbonate resin and polytetrafluoroethylene are damaged, resulting in a decrease in flame retardancy and an easy decrease in the retention impact strength. On the other hand, if the average weight is large, melting becomes insufficient, and vent-up and strand breakage are likely to occur.

[0019] The resin pellets (A) may be unused so-called virgin pellets, or may be recycled material (reclaimed material) pellets or those containing recycled material pellets. Examples of the raw materials for the recycled material pellets include optical discs such as CDs and DVDs, light guide plates, vehicle transparent members such as automotive window glass and automotive headlamp lenses, windshields, containers such as water bottles, spectacle lenses, building members such as soundproof walls, glass windows, and corrugated sheets. Also, it may be pulverized products obtained from defective products during molding, sprues or runners, etc., and those obtained by pulverizing, washing, separating and recovering these and then repelletizing them. Hereinafter, these recycled materials, reclaimed materials, repellets, etc. are collectively referred to as recycled materials or recycled pellets.

[0020] The method for producing the polycarbonate resin composition pellets of the present invention preferably uses recycled material pellets in particular. The use of recycled material pellets is preferable because the LCA (Life Cycle Assessment) becomes low. Recycled materials often contain other resins and various additives in addition to the polycarbonate resin, but any of them can be used as long as the polycarbonate resin is more than 40% by mass as the resin pellets (A). It is also possible to purchase and use the pellets of the recycled material of the polycarbonate resin from the manufacturer of the recycled material.

[0021] [Polycarbonate resin] Examples of the polycarbonate resin include aromatic polycarbonate resins, aliphatic polycarbonate resins, and aromatic-aliphatic polycarbonate resins. Preferably, it is an aromatic polycarbonate resin. Specifically, an aromatic polycarbonate polymer or copolymer obtained by reacting an aromatic dihydroxy compound with phosgene or a diester of carbonic acid is used.

[0022] 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), tetramethyl bisphenol A, α,α'-bis(4-hydroxyphenyl)-p-diisopropylbenzene, hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, and the like.

[0023] Preferred examples of the polycarbonate resin include a polycarbonate resin in which bisphenol A or a combination of bisphenol A and another aromatic dihydroxy compound is used as the dihydroxy compound, and a polycarbonate resin in which bisphenol C or a combination of bisphenol C and another aromatic dihydroxy compound (particularly bisphenol A) is used.

[0024] The polycarbonate resin may be a homopolymer composed of one kind of repeating unit or a copolymer having two or more kinds of repeating units. At this time, various copolymerization forms such as a random copolymer and a block copolymer can be selected for the copolymer. The method for producing the aromatic polycarbonate resin is not particularly limited, and it can be carried out by a conventional method such as the phosgene method (interfacial polymerization method) or the melt method (transesterification method).

[0025] 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 not less than the lower limit value of the above range, the mechanical strength of the polycarbonate resin composition can be further improved, which is more preferable when used in applications with high requirements for mechanical strength. On the other hand, by setting the viscosity average molecular weight to be not more than the upper limit value of the above range, the decrease in the fluidity of the polycarbonate resin composition can be suppressed and improved, the molding processability can be enhanced, and thin-walled molding can also be easily carried out. Two or more types of polycarbonate resins having different viscosity-average molecular weights may be mixed and used. In this case, a polycarbonate resin having a viscosity-average molecular weight outside the above preferred range may be mixed.

[0026] In the present invention, the viscosity-average molecular weight (Mv) of the polycarbonate resin is a value calculated from the following Schnell viscosity formula by measuring the viscosity of a methylene chloride solution of the polycarbonate resin at 25 °C using an Ubbelohde viscometer and obtaining the intrinsic viscosity ([η]). [η]=1.23×10 -4 Mv 0.83

[0027] The method for producing the polycarbonate resin is not particularly limited, and polycarbonate resins produced by any of 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. Examples of the used products preferably include optical recording media such as optical disks (CD, DVD), light guide plates, vehicle transparent members such as automotive window glass, automotive headlamp lenses, and windshields, containers such as water bottles, spectacle lenses, building members such as soundproof walls, glass windows, and corrugated sheets. Further, as the recycled polycarbonate resin, defective products during molding, pulverized products obtained from sprues or runners, or pelletized products obtained by melting them can also be used.

[0028] [Phosphorus-based flame retardant (B)] The phosphorus-based flame retardant (B) in the present invention is a compound containing phosphorus in the molecule, and may be a low molecule, an oligomer, or a polymer. However, from the viewpoint of thermal stability, for example, a condensed phosphoric acid ester compound represented by the following general formula (1) and phosphazene compounds represented by general formulas (2) and (3) are preferable.

[0029]

Chemical formula

[0030]

Chem.

[0031] <Condensed phosphate ester compound> The condensed phosphate ester compound represented by the general formula (1) may be a mixture of compounds having different values of k. In the case of a mixture of condensed phosphate esters with different values of k, k is the average value of those mixtures. k is usually an integer from 0 to 5. In the case of a mixture of compounds having different numbers of k, the average number of k is preferably in the range of 0.5 to 2, more preferably 0.6 to 1.5, still more preferably 0.8 to 1.2, and particularly preferably 0.95 to 1.15.

[0032] Also, X 1 represents a divalent arylene group, and examples thereof include divalent groups 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, 2,7-dihydroxynaphthalene. Among these, divalent groups derived particularly from resorcinol, bisphenol A, and 3,3'-dihydroxybiphenyl are preferred.

[0033] Also, in the general formula (1), p, q, r, and s each represent 0 or 1, and among them, 1 is preferred. Also, R 1 、R 2 、R 3and R 4 each represents 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. Examples of such aryl groups include a phenyl group, a cresyl group, a xylyl group, an isopropylphenyl group, a butylphenyl group, a tert-butylphenyl group, a di-tert-butylphenyl group, a p-cumylphenyl group, etc., and a phenyl group, a cresyl group, and a xylyl group are more preferable.

[0034] Specific examples of the condensed phosphate ester compound represented by the general formula (1) include aromatic phosphate esters such as triphenyl phosphate (TPP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), cresyl diphenyl phosphate (CDP), 2-ethylhexyl diphenyl phosphate (EHDP), tert-butylphenyl diphenyl phosphate, bis-(tert-butylphenyl)phenyl phosphate, tris-(tert-butylphenyl)phosphate, isopropylphenyl diphenyl phosphate, bis-(isopropylphenyl)diphenyl phosphate, tris-(isopropylphenyl)phosphate, etc.; condensed phosphate esters such as resorcinol bis-diphenyl phosphate (RDP), resorcinol bis-dixylenyl phosphate (RDX), bisphenol A bis-diphenyl phosphate (BDP), biphenyl bis-diphenyl phosphate, etc.; and the like.

[0035] The acid value of the condensed phosphate ester compound represented by the general formula (1) is preferably 0.2 mgKOH / g or less, more preferably 0.15 mgKOH / g or less, still more preferably 0.1 mgKOH / g or less, and particularly preferably 0.05 mgKOH / g or less. The lower limit of such an acid value can be substantially 0. On the other hand, the content of the half ester is more preferably 1.1 parts by mass or less, and still more preferably 0.9 parts by mass or less. When the acid value exceeds 0.2 mgKOH / g or the half ester content exceeds 1.5 mg, it causes a decrease in the thermal stability and hydrolysis resistance of the polycarbonate resin composition of the present invention.

[0036] As phosphate ester compounds, in addition to those described above, 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,3-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,4-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, polyester resins, polycarbonate resins or epoxy resins containing a phosphate ester moiety are of course also included.

[0037] <Phosphazene compound> Examples of the phosphazene compounds represented by general formulas (2) and (3) include, for example, phenoxyphosphazene, (poly)tolyloxyphosphazene (e.g., o-tolyloxyphosphazene, m-tolyloxyphosphazene, p-tolyloxyphosphazene, o,m-tolyloxyphosphazene, o,p-tolyloxyphosphazene, m,p-tolyloxyphosphazene, o,m,p-tolyloxyphosphazene, etc.), (poly)xylyloxyphosphazene, etc., cyclic and / or chain C 1-6 alkyl C 6-20 aryloxyphosphazene, and (poly)phenoxytolyloxyphosphazene (e.g., phenoxyo-tolyloxyphosphazene, phenoxym-tolyloxyphosphazene, phenoxyp-tolyloxyphosphazene, phenoxyo,m-tolyloxyphosphazene, phenoxyo,p-tolyloxyphosphazene, phenoxym,p-tolyloxyphosphazene, phenoxyo,m,p-tolyloxyphosphazene, etc.), (poly)phenoxyxylyloxyphosphazene, (poly)phenoxytolyloxyxylyloxyphosphazene, etc., cyclic and / or chain C 6-20 aryl C 1-10 alkyl C 6-20 aryloxyphosphazene, etc. can be exemplified. Among these, preferably, cyclic and / or chain phenoxyphosphazene, cyclic and / or chain C 1-3 alkyl C 6-20 aryloxyphosphazene, C 6-20 aryloxy C1-3 Alkyl C 6-20 It is aryloxyphosphazene (for example, cyclic and / or linear trilyloxyphosphazene, cyclic and / or linear phenoxytolylphenoxyphosphazene, etc.).

[0038] As the cyclic phosphazene compound represented by the general formula (2), R 5 and R 6 may be the same or different and each represents an aryl group or an alkylaryl group. Examples of such aryl group or alkylaryl group include phenyl group, naphthyl group, methylphenyl group, benzyl group, etc. Among them, cyclic phenoxyphosphazene in which R 5 and R 6 are phenyl groups is particularly preferred.

[0039] Examples of such cyclic phenoxyphosphazene compounds include compounds such as phenoxycyclotriphosphazene, octaphenoxycyclotetraphosphazene, and decaphenoxycyclopentaphosphazene obtained by substituting a phenoxy group after extracting cyclic chlorophosphazene such as hexachlorocyclotriphosphazene, octachlorocyclotetraphosphazene, and decachlorocyclopentaphosphazene from a cyclic and linear chlorophosphazene mixture obtained by reacting ammonium chloride and phosphorus pentachloride at a temperature of 120 to 130°C.

[0040] In the formula (2), t represents an integer of 3 to 25. Among them, compounds in which t is an integer of 3 to 8 are preferred, and a mixture of compounds with different t values may also be used. Among them, a mixture of compounds in which those with t = 3 are 50% by mass or more, those with t = 4 are 10 to 40% by mass, and those with t = 5 or more are 30% by mass or less in total is preferred.

[0041] In the formula (3), R 7 and R 8 may be the same or different and each represents an aryl group or an alkylaryl group. Examples of such aryl group or alkylaryl group include phenyl group, naphthyl group, methylphenyl group, benzyl group, etc. Among them, R7 and R 8 A chain - like phenoxyphosphazene in which R is a phenyl group is particularly preferred.

[0042] Such a chain - like phenoxyphosphazene compound can be obtained, for example, by ring - opening polymerization of hexachlorocyclotriphosphazene obtained by the above - mentioned method at a temperature of 220 - 250 °C, and then substituting the obtained linear dichlorophosphazene with a polymerization degree of 3 - 10,000 with a phenoxy group. Also, R 9 represents at least one selected from the group consisting of -N = P(OR 7 )3 group, -N = P(OR 8 )3 group, -N = P(O)OR 7 group, -N = P(O)OR 8 group, and R 10 represents at least one selected from the group consisting of -P(OR 7 )4 group, -P(OR 8 )4 group, -P(O)(OR 7 )2 group, -P(O)(OR 8 )2 group. In addition, in formula (3), u represents an integer of 3 - 10,000, preferably 3 - 1,000, more preferably 3 - 100, and even more preferably 3 - 25.

[0043] Also, the phosphazene compound may be a cross - linked phosphazene compound in which a part of it is cross - linked. Having such a cross - linked structure tends to improve the heat resistance. Examples of such cross - linked phosphazene compounds include compounds having a cross - linked structure represented by the following general formula (4), for example, compounds having a cross - linked structure of 4,4’ - sulfonyldiphenylene (bisphenol S residue), compounds having a cross - linked structure of 2,2 - (4,4’ - diphenylene) isopropylidene group, compounds having a cross - linked structure of 4,4’ - oxydiphenylene group, compounds having a cross - linked structure of 4,4’ - thiodiphenylene group, etc., and compounds having a cross - linked structure of 4,4’ - diphenylene group.

Chemical formula

[0044] Among these, more preferable ones are condensed phosphate ester compounds, which have high flame retardancy and high retention impact strength. Condensed phosphate ester compounds include those in solid state and liquid state at room temperature, but the condensed phosphate ester compounds in liquid state at room temperature are more preferable. By supplying this using a liquid addition device such as a liquid addition pump, the condensed phosphate ester compound in liquid state at room temperature can be added uniformly, pellets with a uniform addition amount can be obtained, there is no concern about classification due to mixing of powder raw materials, and stable flame retardancy can be exhibited.

[0045] Here, specifically, room temperature means 23°C. Specific examples of the condensed phosphate ester compound in liquid state at room temperature preferably include bisphenol A bis - diphenyl phosphate, etc. Commercially available products include, for example, "FP - 600" manufactured by ADEKA Corporation, "CR - 741" manufactured by Daihachi Chemical Industry Co., Ltd., etc.

[0046] The content of the phosphorus - based flame retardant (B) is 5 mass% or more and less than 25 mass% based on 100 mass% of the total of (A) to (F), preferably 6 mass% or more, more preferably 8 mass% or more, preferably 22 mass% or less, more preferably 20 mass% or less.

[0047] [Polytetrafluoroethylene (C)] Polytetrafluoroethylene (C) preferably has fibril - forming ability. By having fibril - forming ability, the dripping prevention property during combustion tends to be significantly improved. Polytetrafluoroethylene is made by suspension polymerization method or emulsion polymerization method. Emulsion polymerization products exist as powder - like substances called fine powder or as suspensions (dispersions).

[0048] As the polytetrafluoroethylene (C), polytetrafluoroethylene coated with an organic polymer can also be preferably used. By using the organic polymer-coated polytetrafluoroethylene, the dispersibility can be improved, the surface appearance of the molded product can be improved, and surface foreign matters can be suppressed. As the monomer for producing the organic polymer for coating polytetrafluoroethylene, from the viewpoint of dispersibility when blended with the polycarbonate resin, those having high affinity with the polycarbonate resin are preferable, and aromatic vinyl monomers, (meth)acrylate monomers, and vinyl cyanide monomers are more preferable.

[0049] One type of polytetrafluoroethylene (C) may be used, or two or more types may be used in combination at any combination and any ratio. The content of polytetrafluoroethylene (C) is 0.1 to 1.0% by mass based on 100% by mass in total of (A) to (F).

[0050] [Production of Polycarbonate Resin Composition Pellets] The method for producing the polycarbonate resin composition pellets of the present invention comprises putting the above-described resin pellets (A), phosphorus-based flame retardant (B), polytetrafluoroethylene (C), and other desired components (D)(E)(F) into a twin-screw extruder and kneading in a first kneading section in a first step, adding the (B) to a downstream section of the first kneading section and kneading in a second kneading section in a second step, and then extruding in a strand form from the extruder and cutting into pellets.

[0051] In the production method of the present invention, a twin-screw extruder is used. Various types of twin-screw extruders can be used, and the rotation mode of the screw may be a co-rotating type or a counter-rotating type, but a co-rotating meshing twin-screw extruder is preferable. Further, it is preferable to provide a vent port in the twin-screw extruder that is depressurized or open to the atmosphere.

[0052] FIG. 1 is a cross-sectional view showing an example of the screw configuration of the extruder used in the method of the present invention. Hereinafter, the production method of the present invention will be described with reference to FIG. 1.

[0053] The raw material resin pellets (A) and other components (C) to (E) are supplied to the extruder from the supply port 1 at the base of the twin-screw extruder. The resin pellets (A) are conveyed while being melt-kneaded toward the discharge port 9 on the right in FIG. 1 by the heating of the extruder barrel and the rotation of the screw, and the strands discharged from the discharge port 9 are cut by a granulator and pelletized.

[0054] The resin pellets (A), etc. supplied from the supply port 1 are supplied, conveyed, and preheated in the supply, conveyance, and preheating section 2. The screw for conveyance is preferably composed of normal flight-shaped screw elements.

[0055] Next, the resin pellets (A) are melted in the first kneading section 3. The first kneading section 3 is composed of a configuration with a length of 1.5D to 6.0D (D is the barrel diameter) by combining two or more of an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, a mixing screw, or a rotor screw.

[0056] The R kneading disk is also called a forward-feed kneading disk (hereinafter sometimes referred to as R). Usually, there are two or more blades, and the twist angle Θ of the blades is from 10 degrees to 75 degrees. By installing the blades shifted by a predetermined angle in this way, the resin can be fed and a strong shearing force can be applied. The N kneading disk is also called an orthogonal kneading disk (hereinafter sometimes referred to as N). Usually, there are two or more blades, and the twist angle Θ of the blades is from 75 degrees to 105 degrees. Since the blades are installed with a shift of approximately 90 degrees, there is almost no force to feed the resin, but the kneading force is strong. The L kneading disk is also called a reverse-feed kneading disk (hereinafter sometimes referred to as L), usually having two or more blades, and the twist angle Θ of the blades is from -10 degrees to -75 degrees. The L kneading disk is an element that dams the incoming resin and has a pressure boosting ability in the direction of sending the sent resin back. By being provided on the downstream side of the element that promotes kneading, it dams the resin and exhibits a strong kneading effect. The L screw is also called a reverse-feed screw. It is a screw that spirals in the opposite direction to a normal feed screw. It is an element that dams the resin and has a pressure boosting ability in the direction of sending the sent resin back. Similar to the L kneading disk, by being provided on the downstream side of the element that promotes kneading, it dams the resin and exhibits a strong kneading effect.

[0057] The above-mentioned blades are usually elliptical, and flat portions are provided at the two vertices of the ellipse. This blade is also called a disk, and each kneading disk is usually composed of 3 to 7 disks. This disk may be substantially triangular and have three vertices, and is also called a three-blade kneading disk. Similarly, there are R, N, and L types. These can also be used in the same way. Among the kneading disks, there are also twist kneading disks in which the vertices are twisted in the screw axis direction, and similar kneading effects can be obtained.

[0058] The seal ring is a ring-shaped one that fits onto the screw, blocks about 70 to 90% of the flow path, retains the flow of the resin, and thereby can increase the resin pressure. Similar to the L kneading, by being provided on the downstream side of the element that promotes kneading, it dams the resin and can exhibit a strong kneading effect. The mixing screw is formed by cutting the crest portion of the screw flight. It is a single or double-feed or reverse-feed screw and is an element having a strong shear dispersion force. There are a forward-feed notch type mixing screw and a reverse-feed notch type mixing screw. The rotor screw forms an elliptical shape (two-wing structure) or a triangular rotor blade, and a strong shearing force can be generated by the gap (chip clearance) between the rotor and the inner wall surface of the barrel.

[0059] The first kneading section 3 combines two or more of the above-mentioned components. Preferably, a combination of an R kneading disk, an N kneading disk, and an L kneading disk is preferred. For example, a configuration in which a plurality of Ns are arranged after R and then L, particularly RNNL, RNNNL, etc. are preferred.

[0060] Also, the disk configuration of the first kneading section has a length of 1.5D to 6.0D, preferably in the range of 2.0 to 5.5D.

[0061] This first kneading section can be divided into a plurality of parts. A normal flight screw element may be arranged after RL or RNL, and then RL or RNL may be connected. What is important is the total length of the first kneading section. The normal flight screw element has no kneading effect and is not included in the length of the kneading section. It is not included in the length of 1.5D to 6.0D.

[0062] Due to the first kneading section configured as described above, sufficient melting of the resin pellets (A) is achieved, and then they are conveyed to the second kneading section 6 by the conveying section 4. At this time, a liquid phosphate ester flame retardant (B) is added by a liquid adding device 5 (such as a liquid supply pump) provided downstream of the first kneading section. Due to the first kneading section configured as described above, sufficient melting of the resin pellets (A) is achieved, and then a phosphorus-based flame retardant (B) is added. They are conveyed to the second kneading section 6 by the conveying section 4, and it may be added at this time. When the phosphorus-based flame retardant (B) is liquid at room temperature, it is added in a liquid state by the liquid adding device 5 (such as a liquid supply pump).

[0063] The addition amount of the phosphorus-based flame retardant (B) is 5% by mass or more and less than 25% by mass with respect to 100% by mass of the obtained polycarbonate resin composition pellets. By setting the addition amount in such a range, high flame retardancy and heat resistance can be achieved simultaneously. When the addition amount is 25% by mass or more, the heat resistance decreases. The addition amount is preferably 7% by mass or more, more preferably 10% by mass or more, preferably 23% by mass or less, and more preferably 21% by mass or less.

[0064] In the second kneading section 6, the molten resin pellets (A) and the like and the phosphorus-based flame retardant (B) are melt-kneaded.

[0065] The second kneading section 6 is composed of a configuration with a length of 1.3D to 6.5D, which is a combination of two or more of an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, a mixing screw, or a rotor screw. By setting the screw configuration of the second kneading section 6 as described above and combining it with the screw configuration of the first kneading section 3, homogeneous melt-kneading of the resin pellets (A) and the phosphorus-based flame retardant (B), particularly a liquid phosphate ester flame retardant, can be achieved, and polycarbonate resin composition pellets with stable productivity, uniform and excellent flame retardancy, and excellent hue can be produced.

[0066] The second kneading section combines two or more of the above-mentioned components. Preferably, a combination of an R kneading disk, an N kneading disk, and an L kneading disk is preferred. For example, it is preferred to arrange a plurality of Ns after R and then have an L configuration. In particular, RNL, RNNL, RNNNL, RNNNNL, RNNNNNL, etc. are preferred.

[0067] Also, the disk configuration of the second kneading section has a length of 1.3D to 6.5D, but is preferably in the range of 2.0D to 6.0D.

[0068] This second kneading section, like the first kneading section, can be divided into a plurality of parts. Ordinary flighted screw elements can be arranged after RL or RNL, and then RL or RNL can be connected. What is important is the total length of the second kneading section. Ordinary flighted screw elements have no kneading effect and are not included in the length of the kneading section. They are not included in the length of 1.3D to 6.5D.

[0069] After the second kneading section 6, preferably at the downstream part of the kneading section, the vent 7 is depressurized for devolatilization, and by the extrusion section 8, the polycarbonate resin composition is extruded in a strand shape from the extrusion die at the discharge section 9 at the tip of the extruder.

[0070] The rotational speed of the screw of the twin-screw extruder is preferably about 500 to 900 rpm. The preferred discharge amount in the extruder is such that the value obtained by dividing the extrusion weight Q (g / sec) per unit second by the cube of the barrel diameter D (cm) is from 0.5 g / cm 3 ·sec to 2 g / cm 3 ·sec. More preferably, it is in the range of 0.7 to 1.7 g / cm 3 ·sec, and even more preferably, it is in the range of 0.9 to 1.4 g / cm 3 ·sec. If it is too small, the polycarbonate resin and polytetrafluoroethylene are likely to be damaged, and the flame retardancy and retention impact strength are likely to decrease. If it is too large, the melting of the polycarbonate is likely to be insufficient, and vent up and strand breakage are likely to occur. Since the barrel diameter D of the representative twin-screw extruder TEM41SX manufactured by Shibaura Machine Co., Ltd. is 4.1 cm, in this case 0.5 g / cm 3 ·sec corresponds to 34.5 g / sec and a discharge amount of 124 kg / h, and 2 g / cm 3 ·sec corresponds to 496 kg / h. Also, 0.7 g / cm 3 ·sec corresponds to 174 kg / h, and 1.7 g / cm 3 ·sec corresponds to 422 kg / h.

[0071] Then, the strand-shaped melt of the extruded polycarbonate resin composition is preferably cooled in water and cut into pellets. The shape of the extrusion die is not particularly limited, and known ones are used. The diameter of the die of the discharge nozzle is usually about 2 to 5 mm, although it also depends on the extrusion pressure and the desired dimensions of the pellets. The temperature of the polycarbonate resin immediately after extrusion is preferably about 250 to 300°C, more preferably about 260 to 290°C.

[0072] In the method of the present invention, in addition to the resin pellet (A), the phosphorus-based flame retardant (B), and the polytetrafluoroethylene (C), it is also preferable to blend a polycarbonate resin flake (D), an ABS resin (E), and other additives (F) other than (B) and (C). The blending amount of each component is based on 100% by mass of the total of (A) to (F), 0 to 50% by mass of the polycarbonate resin flake (D), 0 to 30% by mass of the ABS resin (E), and 0 to 15% by mass of other additives (F) other than (B) and (C). Such components (D) to (F) are supplied from the supply port at the base of the twin-screw extruder together with the resin pellet (A) or by separate feeding, except in cases where side feeding is particularly preferred.

[0073] The polycarbonate resin flake (D) preferably has an average particle size of 2 mm or less, more preferably 1.5 mm or less. By supplying the flaky polycarbonate resin, the generation of unmelted matter and the aggregation of additives are suppressed, and a homogeneous polycarbonate resin composition pellet is easily obtained. The polycarbonate resin of the polycarbonate resin flake (D) is as described above. When using the polycarbonate resin flake (D), the blending amount is preferably 5 to 45% by mass.

[0074] The ABS resin (E) preferably consists of an aromatic vinyl monomer component, a vinyl cyanide monomer component, and a diene rubber-like polymer component, and an acrylonitrile-butadiene-styrene copolymer is preferred. The ABS resin (E) in pellet form is preferably supplied from the supply port 1 at the base of the twin-screw extruder together with the resin pellet (A). When using the ABS resin (E), the blending amount is preferably 5 to 25% by mass.

[0075] Examples of additives (F) other than phosphorus-based flame retardant (B) and polytetrafluoroethylene (C) include various elastomers (impact modifiers), mold release agents, stabilizers, fillers, reinforcing agents, other resin components, flame retardants other than phosphorus-based flame retardant (B), coloring materials (dyes and pigments), ultraviolet absorbers, antistatic agents, antifogging agents, antiblocking agents, fluidity improvers, plasticizers, dispersants, antibacterial agents, etc. When using additives (F) other than (B) and (C), the blending amount is 15% by mass or less, preferably 13% by mass or less, more preferably 12% by mass or less, particularly preferably 11% by mass or less, and especially preferably 10% by mass or less.

[0076] The flame-retardant polycarbonate resin composition pellets obtained by the production method of the present invention are composed of 30 to 85% by mass, preferably 30 to 80% by mass, of the resin derived from resin pellets (A), 5% by mass or more and less than 25% by mass of phosphorus-based flame retardant (B), 0.1 to 1.0% by mass of polytetrafluoroethylene (C), 0 to 50% by mass of the polycarbonate resin derived from polycarbonate resin flakes (D), 0 to 30% by mass of ABS resin (E), and 0 to 15% by mass of additives (F) other than (B) and (C) [however, the total of (A) to (E) is 100% by mass].

[0077] The method for producing a molded article from the obtained polycarbonate resin composition pellets is not particularly limited, and molding methods generally employed for polycarbonate resins can be adopted, that is, general injection molding methods, ultra-high-speed injection molding methods, injection compression molding methods, multi-color injection molding methods, gas-assisted injection molding methods, molding methods using heat-insulating molds, molding methods using rapid heating and cooling molds, foam molding (including supercritical fluids), insert molding, IMC (in-mold coating molding) molding methods, extrusion molding methods, sheet molding methods, thermoforming methods, rotational molding methods, lamination molding methods, press molding methods, etc.

[0078] The obtained molded product can be suitably used as parts for OA equipment such as printers and copiers, electrical equipment, electronic equipment, vehicles such as automobiles, OA equipment such as printers and copiers, houses, buildings, and others. In particular, it can be suitably used as a housing for OA equipment such as printers and copiers, computers, personal computers, various portable terminals, batteries, and the like.

Example

[0079] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the following examples.

[0080] The screw configurations of the extruders used in the examples and comparative examples are as follows. <Configuration Example of the First Kneading Section> Each of the kneading disks in Configuration Examples 2 to 4 is five in number and the length of each disk is 1D, and each of the kneading disks in Configuration Example 1 is five in number and the length of each disk is 0.5D. Configuration Example 1: RL length 1.0D (equivalent to comparative example) Configuration Example 2: RNL length 3.0D (equivalent to example) Configuration Example 3: RNNNL length 5.0D (equivalent to example) Configuration Example 4: RNNNNNL length 7.0D (equivalent to comparative example) <Configuration Example of the Second Kneading Section> Each of the kneading disks in Configuration Examples 2 to 4 is five in number and the length of the disk is 1D, and each of the kneading disks in Configuration Example 1 is five in number and the length of the disk is 0.5D. Configuration Example 1: RL length 1.0D (equivalent to comparative example) Configuration Example 2: RNL length 3.0D (equivalent to example) Configuration Example 3: RNNNL length 5.0D (equivalent to example) Configuration Example 4: RNNNNNL length 7.0D (equivalent to comparative example)

[0081] The raw materials used in the examples and comparative examples are as shown in Table 1 below.

Table 1

[0082] <Manufacture of Polycarbonate Resin Pellets (Adjustment of Molecular Weight Distribution)> PC-2: 47.5% by mass of the above 7022R, 47.5% by mass of 7025R, and 5% by mass of AL071 were fed into the main supply port at the root of an extruder ("TEM41SX" manufactured by Shibaura Machine Co., Ltd.), and uniformly compounded at a discharge rate of 300 kg / h, a screw rotation speed of 650 rpm, and a cylinder set temperature of 280°C. The strand was extruded, cooled, and cut by a pelletizer to obtain pellets (hereinafter, "PC-2"). The temperature of the strand at this time was 339°C. The average weight of the pellets was 19 mg / piece. PC-2S: The strand was extruded in the same manner as the above PC-2, and the rotation speed of the pelletizer was increased to obtain pellets "PC-2S" with an average weight of 11 mg / piece. PC-2L: The strand was extruded in the same manner as the above PC-2, and the rotation speed of the pelletizer was decreased to obtain pellets "PC-2L" with an average weight of 37 mg / piece. PC-3: 90% by mass of 7025R and 10% by mass of AL071 were compounded in the same manner as the above PC-2 to obtain pellets "PC-3". The temperature of the strand was 347°C. The average weight of the pellets was 20 mg / piece. PC-5: 80% by mass of M7027BF and 20% by mass of AL071 were compounded in the same manner as the above PC-2 to obtain pellets "PC-5". The temperature of the strand was 355°C. The average weight of the pellets was 20 mg / piece. PC-1: 7022R pellets were designated as "PC-1". The average weight of the pellets was 19 mg / piece. PC-4: Recycled polycarbonate resin 2010ANC pellets were designated as "PC-4". The average weight of the pellets was 20 mg / piece.

[0083] <Flow rate per unit time: Q value (unit: ×10 -2cm 3 Measurement of ( / sec) After drying each of the above pellets at 80°C for 5 hours using a hot air circulation dryer, using the "Flow Tester CFT-500D" manufactured by Shimadzu Corporation, at 280°C and 160 kg / cm 2 Apply a load of, extrude the resin from a nozzle with a nozzle diameter of 1 mm and a nozzle length of 10 mm, and measure the volume of the resin flowing per second (unit: ×10 -2 cm 3 / sec) and used it as an index of fluidity.

[0084] Measurement of Molecular Weight Distribution (Mw / Mn) The Mw and Mn of each of the above pellets were measured in terms of polystyrene under the following apparatus and measurement conditions, and Mw / Mn was calculated. Apparatus: HLC-8320GPC / EcoSEC (TOSOH) Column: 3 Shodex KF-805L (8.0 mm I.D., 300 mm) Detector: UV-8320 Detection wavelength: 254 nm Column temperature: 40°C Flow rate: 1.2 mL / min Injection volume: 200 μL Eluent: Tetrahydrofuran For calibration curve: Standard polystyrene (used at 8 points) Sample solution concentration: 0.3%

[0085] The Mw / Mn, Q value (unit: ×10 -2 cm 3 / sec), and the average weight of the pellets (mg / piece) are shown in Table 2 below.

[0086]

Table 2

[0087] <Example A1> 150 kg / h (50 mass%) of polycarbonate resin pellets (PC-2), 95.1 kg / h (31.7 mass%) of polycarbonate resin flakes (D1), 18 kg / h (6 mass%) of impact modifier (F1), and 0.9 kg / h (0.3 mass%) of polytetrafluoroethylene (C1) were fed into a co-rotating twin-screw extruder (manufactured by Shibaura Machine Co., Ltd., model "TEM41SX", barrel diameter D: 41 mm) from the feed port at the cylinder position C1, kneaded in the first kneading section of screw configuration example 3, and then 36 kg / h (12 mass%) of phosphorus-based flame retardant (B1) was added from a liquid supply pump at C10, kneaded in the second kneading section of screw configuration example 2, then depressurized at the vent, extruded from the discharge port to form strands, cooled in a water tank, and then cut by a pelletizer to obtain polycarbonate resin composition pellets. The screw rotation speed was 650 rpm, and the cylinder set temperature was 260 °C.

[0088] <Flammability Evaluation UL94 Test> After drying the pellets obtained by the above method at 80 °C for 5 hours, injection molding was performed using a SE100DU type injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. under the conditions of a cylinder temperature of 270 °C and a mold temperature of 80 °C to form UL test specimens with a length of 125 mm, a width of 13 mm, and a thickness of 0.8 mm. For the evaluation of flammability, the UL test specimens obtained above were conditioned in a constant temperature chamber at a temperature of 23 °C and a humidity of 50% for 48 hours, and the test was carried out in accordance with the UL94 test (combustion test for plastic materials for parts of equipment) defined by Underwriters Laboratories (UL) in the United States. A total of 10 flame contacts were made on 5 test specimens, and the total flaming combustion time was determined. In the case of flame-retardant polycarbonate, the total flaming combustion time needs to be 50 seconds or less. For more stable expression of flame retardancy, the total flaming combustion time is preferably 40 seconds or less. For even more stable expression of flame retardancy, the total flaming combustion time is preferably 30 seconds or less.

[0089] <Measurement of Retained Molding Impact Strength> Preparation of Test Specimens After drying the pellets obtained above at 80°C for 5 hours, using the injection molding machine "SG75MII" manufactured by Sumitomo Heavy Industries, Ltd., under the conditions of a cylinder temperature of 300°C and a mold temperature of 80°C, an ISO multi-purpose test piece with a thickness of 3 mm was molded in 7 shots with a molding cycle of 5 minutes. In accordance with ISO179-1 and ISO179-2, using an ISO multi-purpose test piece, at 23°C, the notched Charpy impact strength (unit: kJ / m 2 ) was measured. The average of 7 samples was taken as the dwell molding impact strength. The dwell molding Charpy impact strength should be 30 kJ / m or more in the system with an impact resistance improver added, preferably 40 kJ / m 2 or more. In the system without an impact strength improver added, 8 kJ / m 2 or more is required, preferably 9 kJ / m 2 or more. 2 The results are shown in Table 3.

[0090] There was no vent up, the strand take-up was stable, and the productivity was good. The total flaming combustion time was also 50 seconds or less, which was good, and the dwell molding impact resistance strength was also 40 kJ / m or more, which was good. 2

[0091] <Example A2> It was carried out in the same manner as in Example A1, except that the first kneading section of the screw configuration was RNL of Configuration Example 2. <Example A3> It was carried out in the same manner as in Example A1, except that the second kneading section of the screw configuration was RNNNL of Configuration Example 3. <Example A4> It was carried out in the same manner as in Example A1, except that the polycarbonate resin pellet PC-2 was changed to PC-3. <Example A5> It was carried out in the same manner as in Example A1, except that the polycarbonate resin pellet PC-2 was changed to PC-4. <Example A6> It was carried out in the same manner as in Example A1, except that the polycarbonate resin pellet PC-2 was changed to PC-2S. <Example A7> Except for using polycarbonate resin pellet PC-2 as PC-2L, it was carried out in the same manner as in Example A1. There was a slight vent-up at the edge of the vent hardware, and the strand broke about once every 10 minutes, but it was not to the extent that production was impossible.

[0092] <Comparative Example A1> Except for using RL (length 1.0D) of Configuration Example 1 for the first kneading section of the screw configuration, it was carried out in the same manner as in Example A1. However, vent-up occurred, the strand broke, and pellets could not be collected. <Comparative Example A2> Except for using RL (length 1.0D) of Configuration Example 1 for the first kneading section of the screw configuration and RNNNL of Configuration Example 3 for the second kneading section, it was carried out in the same manner as in Example A1. However, vent-up occurred, the strand broke, and pellets could not be collected. <Comparative Example A3> Except for using RNNNNNL of Configuration Example 4 for the first kneading section of the screw configuration, it was carried out in the same manner as in Example A1. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. Probably, the screw configuration strongly damaged polytetrafluoroethylene, and the flame retardancy decreased.

[0093] <Comparative Example A4> Except for using RL (length 1.0D) of Configuration Example 1 for the second kneading section of the screw configuration, it was carried out in the same manner as in Example A1. However, vent-up occurred, the strand broke, and pellets could not be collected. <Comparative Example A5> Except for using RNNNNNL of Configuration Example 4 for the second kneading section of the screw configuration, it was carried out in the same manner as in Example A1. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. Probably, the screw configuration strongly damaged polytetrafluoroethylene, and the flame retardancy decreased. <Comparative Example A6> Except for using polycarbonate resin pellet PC-2 as PC-1, it was carried out in the same manner as in Example A1. The total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. It is considered that the molecular weight distribution of the polycarbonate resin pellet was narrow, the dripping speed during combustion was fast, and the flame retardancy deteriorated. <Comparative Example A7> Except for using polycarbonate resin pellet PC-2 as PC-5, it was carried out in the same manner as in Example A1. Although the flame retardancy was good, the retention molding Charpy impact strength decreased. It is considered that the high molecular weight components in the polycarbonate resin pellet with a wide molecular weight distribution were damaged during the kneading process, resulting in a decrease in the retention molding impact strength.

[0094] The above results are shown in Table 3 below. In the table, the judgment in the column of "flammability & retention impact strength" is that the total flaming combustion time is 50 seconds or less, and the retention molding impact strength is 30 kJ / m 2 The above were marked as "〇", and the others were marked as "×". Also, the evaluation of productivity (〇, △, ×) was judged according to the following criteria and described in Table 3. Note that Tables 4-5 and 7 described later were also judged according to the same criteria. 〇: There is no vent up, the strand take-up is stable, and the productivity is good. △: Slight vent up is observed, and the strand sometimes breaks, but it is not to the extent that production cannot be carried out. ×: Vent up occurs, the strand breaks, and pellets cannot be collected. In each of the following tables, "Ex." represents an example, and "Comp." represents a comparative example.

[0095]

Table 3

[0096] <Example B1> 249 kg / h (83% by mass) of polycarbonate resin pellets (PC-2) and 0.9 kg / h (0.3% by mass) of polytetrafluoroethylene (C1) were fed into a co-rotating twin-screw extruder (manufactured by Shibaura Machine Co., Ltd., model "TEM41SX", barrel diameter D: 41 mm) from the supply port of C1, kneaded in the first kneading section of screw configuration example 3, and then 50.1 kg / h (16.7% by mass) of a phosphorus-based flame retardant (B1) was added from a liquid supply pump from C10, kneaded in the second kneading section of screw configuration example 2, then evacuated at the vent, extruded from the discharge port to form strands, cooled in a water bath, and cut by a pelletizer to obtain polycarbonate resin composition pellets. The screw rotation speed was 650 rpm, and the cylinder set temperature was 260°C. The obtained pellets were tested in the same manner as in Example A1.

[0097] <Example B2> It was carried out in the same manner as in Example B1, except that the first kneading section of the screw configuration was RNL of Configuration Example 2. <Example B3> It was carried out in the same manner as in Example B1, except that the second kneading section of the screw configuration was RNNNL of Configuration Example 3. <Example B4> It was carried out in the same manner as in Example B1, except that the polycarbonate resin pellets PC-2 were changed to PC-3. <Example B5> It was carried out in the same manner as in Example B1, except that the polycarbonate resin pellets PC-2 were changed to PC-4. <Example B6> It was carried out in the same manner as in Example B1, except that the polycarbonate resin pellets PC-2 were changed to PC-2S. <Example B7> It was carried out in the same manner as in Example B1, except that the polycarbonate resin pellets PC-2 were changed to PC-2L. A slight vent-up was observed at the edge of the vent hardware, and the strand broke about once every 15 minutes, but it was not to the extent that production was impossible.

[0098] <Comparative Example B1> It was carried out in the same manner as in Example B1, except that the first kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1. However, venting occurred, the strand broke, and pellets could not be collected. <Comparative Example B2> It was carried out in the same manner as in Example B1, except that the first kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1 and the second kneading section was RNNNL of Configuration Example 3. However, venting occurred, the strand broke, and pellets could not be collected. <Comparative Example B3> It was carried out in the same manner as in Example A1, except that the first kneading section of the screw configuration was RNNNNNL of Configuration Example 4. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. Presumably, the screw configuration strongly damaged the polytetrafluoroethylene, resulting in a decrease in flame retardancy. <Comparative Example B4> It was carried out in the same manner as in Example A1, except that the second kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1. However, venting occurred, the strand broke, and pellets could not be collected. <Comparative Example B5> It was carried out in the same manner as in Example B1, except that the second kneading section of the screw configuration was RNNNNNL of Configuration Example 4. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. Presumably, the screw configuration strongly damaged the polytetrafluoroethylene, resulting in a decrease in flame retardancy. <Comparative Example B6> It was carried out in the same manner as in Example B1, except that the polycarbonate resin pellets PC-2 were changed to PC-1. The molecular weight distribution of the polycarbonate resin pellets was narrow, the dripping speed during combustion was fast, and it is considered that the flame retardancy deteriorated. <Comparative Example B7> Except for using polycarbonate resin pellets PC-2 as PC-5, the procedure was the same as in Example B1. Although the flame retardancy was good, the retention molding Charpy impact strength decreased. It is considered that the high molecular weight components in the polycarbonate resin pellets with a wide molecular weight distribution were damaged during the kneading process, resulting in a decrease in the retention molding impact strength.

[0099] The above results are shown in Table 4 below. In Table 4, the judgment in the column of "flammability & retention impact strength" was as follows: those with a total flaming combustion time of 50 seconds or less and a retention molding impact strength of 8 kJ / m 2 or more were marked as "〇", and the others were marked as "×".

[0100]

Table 4

[0101] <Example C1> 180 kg / h (60 mass%) of polycarbonate resin pellets (PC-2), 17.1 kg / h (5.7 mass%) of polycarbonate resin flakes (D1), 45 kg / h (15 mass%) of ABS resin (E1), 12 kg / h (4 mass%) of impact modifier (F1), and 0.9 kg / h (0.3 mass%) of polytetrafluoroethylene (C1) were fed from the supply port of C1 into a co-rotating twin-screw extruder ("TEM41SX" manufactured by Shibaura Machine Co., Ltd., barrel diameter D: 41 mm), kneaded in the first kneading section of screw configuration example 3, and then 45 kg / h (15 mass%) of phosphorus-based flame retardant (B1) was added from a liquid supply pump from C10, kneaded in the second kneading section of screw configuration example 2, then evacuated at the vent, extruded from the discharge port to form strands, cooled in a water tank, and cut by a pelletizer to obtain polycarbonate resin composition pellets. The screw rotation speed was 650 rpm, and the cylinder set temperature was 260 °C. The obtained pellets were tested in the same manner as in Example A1.

[0102] <Example C2> The procedure was the same as in Example C1 except that the first kneading section of the screw configuration was RNL of configuration example 2. <Example C3> It was carried out in the same manner as in Example C1, except that the second kneading section having a screw configuration was set as RNNNL of Configuration Example 3. <Example C4> It was carried out in the same manner as in Example C1, except that the polycarbonate resin pellets PC-2 were changed to PC-3. <Example C5> It was carried out in the same manner as in Example C1, except that the polycarbonate resin pellets PC-2 were changed to PC-4. <Example C6> It was carried out in the same manner as in Example C1, except that the polycarbonate resin pellets PC-2 were changed to PC-2S. <Example C7> It was carried out in the same manner as in Example C1, except that the polycarbonate resin pellets PC-2 were changed to PC-2L. A vent up was slightly observed at the edge of the vent hardware, and the strand broke about once every 15 minutes, but it was not to the extent that production was impossible.

[0103] <Comparative Example C1> It was carried out in the same manner as in Example C1, except that the first kneading section having a screw configuration was set as RL (length 1.0D) of Configuration Example 1. However, a vent up occurred, the strand broke, and pellets could not be collected. <Comparative Example C2> It was carried out in the same manner as in Example C1, except that the first kneading section having a screw configuration was set as RL (length 1.0D) of Configuration Example 1, and the second kneading section was set as RNNNL of Configuration Example 3. However, a vent up occurred, the strand broke, and pellets could not be collected. <Comparative Example C3> It was carried out in the same manner as in Example C1, except that the first kneading section having a screw configuration was set as RNNNNNL of Configuration Example 4. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. It is considered that perhaps the screw configuration strongly damaged the polytetrafluoroethylene and the flame retardancy decreased. <Comparative Example C4> It was carried out in the same manner as in Example C1, except that the second kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1. However, venting occurred, the strand broke, and pellets could not be collected. <Comparative Example C5> It was carried out in the same manner as in Example C1, except that the second kneading section of the screw configuration was RNNNNNL of Configuration Example 4. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. It is considered that the screw configuration strongly damaged the polytetrafluoroethylene and the flame retardancy decreased. <Comparative Example C6> It was carried out in the same manner as in Example C1, except that the polycarbonate resin pellet PC-2 was changed to PC-1. The molecular weight distribution of the polycarbonate resin pellet was narrow, the dripping rate during combustion was fast, and it is considered that the flame retardancy deteriorated. <Comparative Example C7> It was carried out in the same manner as in Example C1, except that the polycarbonate resin pellet PC-2 was changed to PC-5. Although the flame retardancy was good, the retention molded Charpy impact strength decreased. It is considered that the high molecular weight components in the polycarbonate resin pellet with a wide molecular weight distribution were damaged during the kneading process, resulting in a decrease in the retention molded impact strength.

[0104] The above results are shown in Table 5. In Table 5, the judgment in the column of "flammability & retention impact strength" is that when the total flaming combustion time is 50 seconds or less and the retention molded impact strength is 30 kJ / m 2 or more, it is marked as "〇", and the others are marked as "×".

[0105]

Table 5

[0106] <Production of Polycarbonate Resin / ABS Resin Pellets> PC / ABS-1: Feed 85.7% by mass of 7022R and 14.3% by mass of ABS resin (E1) to the base of TEM41SX. Using the screw configuration diagram 1, set the cylinder temperature to 280 °C, compound at a discharge rate of 300 kg / h and a screw rotation speed of 650 rpm, extrude the strand, cool it, and cut it with a pelletizer to obtain pellets (PC / ABS-1). The strand temperature at this time was 335 °C. The average weight of the pellets was 20 mg / piece.

[0107] PC / ABS-2: Compound 77.13% by mass of 7025R, 8.57% by mass of AL071, and 14.3% by mass of ABS resin (E1) in the same manner as the above PC / ABS-1 to obtain pellets (PC / ABS-2). The strand temperature was 345 °C. The average weight of the pellets was 20 mg / piece.

[0108] PC / ABS-2S: After extruding the strand in the same manner as above, increase the rotation speed of the pelletizer to obtain pellets (PC / ABS-2S) with an average weight of 11 mg / piece. PC / ABS-2L: After extruding the strand in the same manner as above, decrease the rotation speed of the pelletizer to obtain pellets (PC / ABS-2L) with an average weight of 37 mg / piece.

[0109] PC / ABS-3: Compound 85.7% by mass of 2010ANC and 14.3% by mass of ABS resin (E1) in the same way to obtain pellets (PC / ABS-3). The strand temperature was 340 °C. The average weight of the pellets was 20 mg / piece.

[0110] PC / ABS-4: Compound 68.56% by mass of M7027BF, 17.14% by mass of AL071, and 14.3% by mass of ABS resin (E1) in the same way to obtain pellets (PC / ABS-4). The strand temperature was 351 °C. The average weight of the pellets was 19 mg / piece.

[0111] The Q values of these PC / ABS pellets were measured. The molecular weight distribution of the polycarbonate resin in the polycarbonate resin / ABS resin pellets was determined by filtering out the THF-soluble fraction, calculating Mw and Mn from this using the aforementioned method, and then calculating Mw / Mn. The Mw / Mn, Q value, and average weight of the above PC / ABS pellets are summarized in Table 6 below.

[0112]

Table 6

[0113] <Example D1> 210 kg / h (70 mass%) of PC / ABS resin pellets (PC / ABS-2), 17.1 kg / h (5.7 mass%) of polycarbonate resin flakes (D1), 15 kg / h (5 mass%) of ABS resin (E1), 12 kg / h (4 mass%) of impact modifier (F1), and 0.9 kg / h (0.3 mass%) of polytetrafluoroethylene (C1) were fed into a co-rotating twin-screw extruder (manufactured by Shibaura Machine Co., Ltd., "TEM41SX", barrel diameter D: 41 mm) from the supply port of C1, kneaded in the first kneading section of screw configuration example 3, and then 45 kg / h (15 mass%) of phosphorus-based flame retardant (B1) was added from a liquid supply pump from C10, kneaded in the second kneading section of screw configuration example 2, then pulled under reduced pressure at the vent, extruded from the discharge port to form strands, cooled in a water tank, and cut by a pelletizer to obtain polycarbonate resin composition pellets. The screw rotation speed was 650 rpm, and the cylinder set temperature was 260 °C. The obtained pellets were tested in the same manner as in Example A1.

[0114] <Example D2> It was carried out in the same manner as in Example D1, except that the first kneading section of the screw configuration was RNL of Configuration Example 2. <Example D3> It was carried out in the same manner as in Example D1, except that the second kneading section of the screw configuration was RNNNL of Configuration Example 3. <Example D4> Example D1 was repeated, except that the polycarbonate resin pellets PC / ABS-2 were replaced with PC / ABS-3. <Example D5> Example D1 was repeated, except that the polycarbonate resin pellets PC / ABS-2 were replaced with PC / ABS-2S. <Example D6> Example D1 was repeated, except that the polycarbonate resin pellets PC / ABS-2 were replaced with PC / ABS-2L. There was a slight vent up at the edge of the vent hardware, and the strand broke about once every 10 minutes, but it was not to the extent that production was impossible.

[0115] <Comparative Example D1> Example D1 was repeated, except that the first kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1. However, vent up occurred, the strand broke, and pellets could not be collected. <Comparative Example D2> Example D1 was repeated, except that the first kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1 and the second kneading section was RNNNL of Configuration Example 3. However, vent up occurred, the strand broke, and pellets could not be collected. <Comparative Example D3> Example D1 was repeated, except that the first kneading section of the screw configuration was RNNNNNL of Configuration Example 4. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. Presumably, the screw configuration strongly damaged the polytetrafluoroethylene, resulting in a decrease in flame retardancy. <Comparative Example D4> Example D1 was repeated, except that the second kneading section of the screw configuration was RL (length 1.0D) of Configuration Example 1. However, vent up occurred, the strand broke, and pellets could not be collected. <Comparative Example D5> It was carried out in the same manner as in Example D1, except that the second kneading section with a screw configuration was set as RNNNNNL in Configuration Example 4. However, the total flaming combustion time exceeded 50 seconds, and the flame retardancy deteriorated. The result was not V-0 in UL94. Probably, the screw configuration strongly damaged the polytetrafluoroethylene, resulting in a decrease in flame retardancy. <Comparative Example D6> It was carried out in the same manner as in Example D1, except that the polycarbonate resin pellet PC / ABS-2 was changed to PC / ABS-1. The molecular weight distribution of the polycarbonate resin pellet was narrow, the dripping speed during combustion was fast, and it is considered that the flame retardancy deteriorated. <Comparative Example D7> It was carried out in the same manner as in Example D1, except that the polycarbonate resin pellet PC / ABS-2 was changed to PC / ABS-4. Although the flame retardancy was good, the retention molding Charpy impact strength decreased. It is considered that the high molecular weight components in the polycarbonate resin pellet with a wide molecular weight distribution were damaged during the kneading process, resulting in a decrease in the retention molding impact strength.

[0116] The above results are shown in Table 7. In Table 7, the judgment in the column of "flammability & retention impact strength" is that the total flaming combustion time is 50 seconds or less and the retention molding impact strength is 30 kJ / m 2 or more is marked as "〇", and the others are marked as "×".

[0117]

Table 7

[0118] In all of the above examples, it can be seen that the flame retardancy of the PC-4 pellets made of recycled polycarbonate resin 2010ANC and the resin composition pellets manufactured using PC / ABS-3 containing the same is good. The recycled pellets undergo many heat histories such as molding, pulverization, and re-kneading. Therefore, the crosslinked structure develops, making it difficult to drip during combustion, and it is considered that the flame retardancy is improved.

Industrial Applicability

[0119] According to the method of the present invention, generation of unmelted matter and vent-up do not occur, and excellent polycarbonate resin composition pellets can be stably produced with high productivity, uniform and excellent flame retardancy, and excellent impact strength that is difficult to decrease even when there is heat retention. The obtained polycarbonate resin pellets can be widely used as materials for manufacturing parts in various fields such as OA equipment such as printers and copiers, electrical equipment, electronic equipment, vehicles such as automobiles, housing, construction, and other industrial fields, and the industrial applicability is very high.

Claims

1. A method for producing flame-retardant polycarbonate resin pellets by a twin-screw extruder, comprising 50 to 85% by mass of resin pellets (A) containing more than 50% by mass of a polycarbonate resin with an Mw / Mn of 2.7 to 3.4 in the pellets, 5% by mass or more and less than 25% by mass of a phosphorus-based flame retardant (B), 0.1 to 1.0% by mass of polytetrafluoroethylene (C), 0 to 45% by mass of polycarbonate resin flakes (D), 0 to 25% by mass of an ABS resin (E), and 0 to 15% by mass of other additives (F) other than (B) and (C) [however, the total of (A) to (F) is 100% by mass], putting the above (A), (C), (D), (E) and (F) into a twin-screw extruder, including a first step of kneading in a first kneading section and a second step of adding the above (B) to a downstream section of the first kneading section and kneading in a second kneading section, wherein the first kneading section is composed of a configuration with a length of 2.0D to 5.5D (D is the barrel diameter) by combining two or more of an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, a mixing screw, or a rotor screw, the second kneading section is composed of a configuration with a length of 2.0D to 6.0D (D is the barrel diameter) by combining two or more of an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, a mixing screw, or a rotor screw, and after the second step, extruding in a strand shape from the twin-screw extruder and cutting, which is characterized in that it is a method for producing flame-retardant polycarbonate resin pellets.

2. The production method according to claim 1, wherein the average weight of the resin pellets (A) is 13 to 35 mg / piece.

3. The production method according to claim 1 or 2, wherein the resin pellets (A) are recycled pellets.

4. The production method according to any one of claims 1 to 3, wherein the phosphorus-based flame retardant (B) is a condensed phosphate ester compound.

5. The production method according to any one of claims 1 to 4, wherein the phosphorus-based flame retardant (B) is a condensed phosphate ester compound that is liquid at room temperature.

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