JP6023381B1 - Polycarbonate resin pellets and method for producing the same - Google Patents

Abstract

Spherical polycarbonate resin pellets with low swarf generation, no internal void generation, and high sphericity are efficiently produced. A pellet of polycarbonate resin having a viscosity average molecular weight of 10,000 to 19000, wherein the pellet has an average minor axis of 1.5 mm or more, a sphericity (major axis / minor axis) of 1 to 1.6, and a bulk. A polycarbonate resin pellet having a density of 0.710 g / ml or more, and a polycarbonate resin having a viscosity average molecular weight of 10,000 to 19000 are melt-kneaded by an extruder, and then in a mist state of water and air. A method for producing polycarbonate resin pellets, which is extruded and cut into a cooling medium having a temperature of 95 to 140 ° C. [Selection] Figure 1

Description

  The present invention relates to a polycarbonate resin pellet and a method for producing the same. More specifically, the present invention relates to a low-molecular weight polycarbonate resin pellet having a high sphericity and less swarf, no internal voids, and hot The present invention relates to a method for efficiently producing by a cutting method.

Polycarbonate resin is a general-purpose engineering plastic with excellent transparency, impact resistance, heat resistance, dimensional stability, etc., and its excellent characteristics make it a wide range of fields such as electrical and electronic equipment parts, OA equipment parts, machine parts, and vehicle parts. Used in.
In recent years, especially in the field of electrical and electronic equipment parts, etc., products are becoming thinner and smaller, and the accompanying complexity of mold shapes is rapidly progressing. Polycarbonate resin materials with excellent moldability, specifically fluidity There is a strong demand for a polycarbonate resin composition having excellent properties, and for such a demand, the molecular weight of the polycarbonate resin is lowered to increase the fluidity.

  To make a polycarbonate resin material into pellets for molding, the polycarbonate resin raw material is conventionally heated in an extruder, melt-kneaded, extruded into a strand shape from a die at the tip of the extruder, and the strand is introduced into a cooling water tank. A strand cutting method is widely adopted in which the product is cooled and solidified and cut with a cutter to obtain cylindrical pellets.

  However, when the polycarbonate resin having a low molecular weight is pelletized, the pellet shape becomes indeterminate, or the pellets adhere to each other to form an adhering pellet, and bubbles (voids) are easily generated inside the pellet. There's a problem. The above-mentioned amorphous or inter-attached pellets generate a large amount of chips during pellet transportation (pneumatic transportation during pellet production or delivery to customers). Chips float in the working atmosphere (air) during actual molding operations. When molding operations are performed in such an environment, chips adhere to molded products and molds, resulting in white spots, and the appearance and design of the product. Will be damaged.

In addition to the strand cutting method, there is a method called hot cutting, which is a rotary cutter that attaches a porous die to the tip of the extruder and provides molten resin immediately after being extruded from the porous die so as to face the porous die. There are an air hot cut method, an underwater hot cut method, and a mist hot cut method depending on the cooling medium for cooling the resin (for example, see Patent Documents 1 and 2).
The air hot cut method is an air cooling method, and cools the pellets cut by the flow of supplied air. The underwater hot cut method is a method in which the pellets after cutting are rapidly cooled by water cooling. The mist hot cut method is a method in which water is cooled by a mist-like cooling medium. In any method, the cooling medium is desired to be as low as possible from the viewpoint of cooling efficiency.

  However, even if the above-described method is simply applied to the above-described low molecular weight polycarbonate resin, it is difficult to say that the pellets obtained are sufficient, and a higher level pellet and a method for producing the pellet have been desired.

Japanese Patent Laid-Open No. 48-75660 Japanese Patent Publication No. 1-24044

  An object (issue) of the present invention is to provide a spherical polycarbonate resin pellet having a high degree of sphericity as well as an efficient generation of pellets with less generation of chips, no generation of internal voids, and such pellets. It is to provide a method of manufacturing.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors are made of a specific low molecular weight polycarbonate resin, the average minor axis of the pellet is 1.5 mm or more, and the sphericity is 1 to 1.6. The high density polycarbonate resin pellets of bulk density of 0.710 g / ml or higher, and such pellets are in a mist state of water and air, and the temperature is in the range of 95 to 140 ° C. It has been found that it can be efficiently produced by extrusion cutting into a certain cooling medium, and has completed the present invention.
The present invention provides the following polycarbonate resin pellets and a method for producing polycarbonate resin pellets.

[1] A polycarbonate resin spherical pellet having a viscosity average molecular weight of 10,000 to 19000, wherein the pellet has an average minor axis of 1.5 mm or more, a sphericity of 1 to 1.6, and a bulk density (JIS K5101-12). -1) (measured in accordance with -1) is 0.710 g / ml or more.
[2] The polycarbonate resin pellet according to the above [1], wherein the bulk density is 0.730 g / ml or more.
[3] After melt-kneading a polycarbonate resin having a viscosity average molecular weight of 10000 to 19000 with an extruder, it is extruded and cut into a cooling medium having a temperature of 95 to 140 ° C. in a mist state of water and air. A method for producing polycarbonate resin pellets.
[4] The method for producing a polycarbonate resin pellet according to [3], wherein the cooling medium is a mist of water and air having a water volume ratio of 0.1% to 100%.
[5] The method for producing a polycarbonate resin pellet according to the above [3] or [4], wherein the cooling medium is a mist of water and air having a water volume ratio of 0.1% or more and less than 100%.

The polycarbonate resin pellet of the present invention is a low-molecular-weight polycarbonate resin pellet, but it is a spherical pellet with low internal bubble generation, high sphericity and bulk density, low chip generation, and filling during molding The ratio is high and the moldability is excellent, and the molded product has less haze.
Moreover, the method for producing resin pellets of the present invention can produce the above polycarbonate resin pellets efficiently and can produce a very small number of bubbles generated inside the pellets.

It is sectional drawing which shows an example of the hot cut system used by this invention. It is a right view of the hot cut system of FIG.

Hereinafter, although an embodiment and an example thing are shown and explained in detail about the present invention, the present invention is limited to the embodiment, an example thing, etc., and is not interpreted.
In the specification of the present application, “to” is used in the sense of including the numerical values described before and after the lower limit and the upper limit unless otherwise specified.

The polycarbonate resin pellet of the present invention is a spherical pellet of polycarbonate resin having a viscosity average molecular weight of 10,000 to 19000, the average minor axis of the pellet is 1.5 mm or more, the sphericity is 1 to 1.6, and the bulk density Is 0.710 g / ml or more.
Moreover, the polycarbonate resin pellet manufacturing method of the present invention is a method in which a polycarbonate resin having a viscosity average molecular weight of 10,000 to 19000 is melt-kneaded with an extruder and then in a mist state of water and air and the temperature is in the range of 95 to 140 ° C. It is characterized by extrusion cutting into a certain cooling medium.

  The polycarbonate resin used in the present invention includes an aromatic polycarbonate resin, an aliphatic polycarbonate resin, and an aromatic-aliphatic polycarbonate resin, preferably an aromatic polycarbonate resin, specifically, an aromatic dihydroxy compound. A thermoplastic aromatic polycarbonate polymer or copolymer obtained by reacting with phosgene or carbonic acid diester is used.

  Aromatic dihydroxy compounds include 2,2-bis (4-hydroxyphenyl) propane (ie, bisphenol A), tetramethylbisphenol A, α, α'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, hydroquinone , Resorcinol, 4,4′-dihydroxydiphenyl, and the like. Among these, as a preferable example of the polycarbonate resin, 2,2-bis (4-hydroxyphenyl) propane as a dihydroxy compound, or 2,2-bis (4-hydroxyphenyl) propane and another aromatic dihydroxy compound are used in combination. A polycarbonate resin is mentioned.

  The method for producing the polycarbonate resin is not particularly limited, but it is usually produced by an interfacial polymerization method (phosgene method) or a melting method (transesterification method).

  In the interfacial polymerization method, the polymerization reaction is usually carried out in the presence of an organic solvent inert to the reaction and an aqueous alkaline solution, and the pH is usually kept at 9 or higher. An aromatic dihydroxy compound and, if necessary, a molecular weight modifier (terminal terminator). Polycarbonate resin by using an antioxidant for preventing oxidation of aromatic dihydroxy compounds and reacting with phosgene, adding a polymerization catalyst such as tertiary amine or quaternary ammonium salt, and conducting interfacial polymerization Get. The addition of the molecular weight regulator is not particularly limited as long as it is from the time of phosgenation to the start of the polymerization reaction. In addition, reaction temperature is 0-40 degreeC, for example, and reaction time is several minutes (for example, 10 minutes)-several hours (for example, 6 hours), for example.

  Here, examples of the organic solvent inert to the reaction include chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, monochlorobenzene and dichlorobenzene. Examples of the alkali compound used in the alkaline aqueous solution include hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide.

  Examples of the molecular weight regulator include compounds having a monovalent phenolic hydroxyl group, such as m-methylphenol, p-methylphenol, m-propylphenol, p-propylphenol, p-tert-butylphenol and p-long chain alkyl. Preferred examples include substituted phenols. The amount of the molecular weight regulator used is preferably 50 to 0.5 mol, more preferably 30 to 1 mol, per 100 mol of the aromatic dihydroxy compound.

  Polymerization catalysts include tertiary amines such as trimethylamine, triethylamine, tributylamine, tripropylamine, trihexylamine, pyridine, and quaternary ammonium salts such as trimethylbenzylammonium chloride, tetramethylammonium chloride, and triethylbenzylammonium chloride. Etc.

  Explaining the melting method, the polymerization reaction in this method is, for example, a transesterification reaction between a carbonic acid diester and an aromatic dihydroxy compound. Examples of the carbonic acid diester include dialkyl carbonate compounds such as dimethyl carbonate, diethyl carbonate and di-tert-butyl carbonate, and substituted diphenyl carbonates such as diphenyl carbonate and ditolyl carbonate. The carbonic acid diester is preferably diphenyl carbonate or substituted diphenyl carbonate, more preferably diphenyl carbonate.

  In the melt transesterification reaction, usually, the mixing ratio of the carbonic acid diester and the aromatic dihydroxy compound and the degree of pressure reduction during the transesterification reaction are adjusted to obtain an aromatic polycarbonate resin having the desired molecular weight and terminal hydroxyl group content adjusted. be able to. Usually, in the melt transesterification reaction, an equimolar amount or more of carbonic acid diester is used with respect to 1 mol of the aromatic dihydroxy compound, among which 1.001 to 1.3 mol, particularly 1.01 to 1.2 mol is used. preferable. Further, as a more aggressive adjustment method, there is a method of adding a terminal terminator separately at the time of reaction, and examples of the terminal terminator in this case include monohydric phenols, monovalent carboxylic acids, and carbonic acid diesters. It is done.

  The polycarbonate resin used in the present invention may be produced by any of the above interfacial polymerization method and melting method.

  As the polycarbonate resin used in the present invention, those having a viscosity average molecular weight Mv of 10,000 to 19000 are used. When the Mv is in such a range, there is a problem that the pellets adhere to each other, the adhesive pellets are easily generated, bubbles are easily generated inside the pellets, and further, chips are easily generated. It has been found that the pellets of the present invention and the process for their production solve these problems. When Mv is less than 10,000, the pellet shape tends to be indefinite, and the strength of the molded product tends to decrease. When it exceeds 19000, the cutting property tends to be poor, and the fluidity becomes insufficient, and the molding of a thin-walled molded product is difficult. It becomes difficult. The viscosity average molecular weight Mv is preferably 10500 or more, more preferably 11000 or more, further preferably 11500 or more, more preferably 18000 or less, still more preferably 17000 or less, and particularly preferably 16000 or less.

Here, the viscosity average molecular weight Mv is obtained by using methylene chloride as a solvent and obtaining the intrinsic viscosity [η] (unit: dl / g) at a temperature of 20 ° C. using an Ubbelohde viscometer, and the Schnell viscosity equation, that is, η = 1.23 × 10 ⁻⁴ Mv ^0.83 . The intrinsic viscosity [η] is a value calculated from the following equation by measuring the specific viscosity [η _sp ] at each solution concentration [C] (g / dl).

  In addition, polycarbonate resin may use together 2 or more types of polycarbonate resins, and what adjusted the molecular weight of 10000-19000 as a whole by using together that whose viscosity average molecular weight Mv is outside the range of 10,000-19000 is used together. It may be used.

The polycarbonate resin used in the present invention preferably contains polyalkylene glycol in order to improve transmittance and hue.
The polyalkylene glycol may be a polymer having a linear alkylene ether unit, a polymer having a branched alkylene ether unit, or a copolymer thereof.

Examples of the polymer having a linear alkylene ether unit include a polymer having a linear alkylene ether unit represented by the following general formula (I).
(In the formula, n is an integer of 3 to 6.)

Moreover, as a polymer which has a branched alkylene ether unit, the polyalkylene glycol polymer which has the branched alkylene ether unit chosen from the unit represented by the following (II-1)-(II-4) is mentioned.
(In the formulas (II-1) to (II-4), R ^{1 to} R ¹⁰ are a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and in each of the formulas (II-1) to (II-4) , At least one of R ^{1 to} R ¹⁰ is an alkyl group having 1 to 3 carbon atoms.)

  Examples of the copolymer having a linear alkylene ether unit and a branched alkylene ether unit include the linear alkylene ether unit (B1) represented by the general formula (I) and the general formulas (II-1) to (II-4). And a copolymer having a branched alkylene ether unit selected from units represented by: The copolymer (B) may be a random copolymer or a block copolymer.

  As the linear alkylene ether unit represented by the general formula (I), when described as glycol, trimethylene glycol in which n is 3, tetramethylene glycol in which n is 4, pentamethylene glycol in which n is 5, Hexamethylene glycol in which n is 6 is preferable, and trimethylene glycol and tetramethylene glycol are more preferable.

  As the branched alkylene ether unit represented by the general formula (II-1), when this is described as glycol, (2-methyl) ethylene glycol, (2-ethyl) ethylene glycol, (2,2-dimethyl) ethylene glycol, etc. Is mentioned.

  As a branched alkylene ether unit represented by the above general formula (II-2), when described as glycol, (2-methyl) trimethylene glycol, (3-methyl) trimethylene glycol, (2-ethyl) trimethylene glycol , (3-ethyl) triethylene glycol, (2,2-dimethyl) trimethylene glycol, (2,2-methylethyl) trimethylene glycol, (2,2-diethyl) trimethylene glycol, (3,3-dimethyl ) Trimethylene glycol, (3,3-methylethyl) trimethylene glycol, (3,3-diethyl) trimethylene glycol and the like.

  As a branched alkylene ether unit represented by the above general formula (II-3), when described as glycol, (3-methyl) tetramethylene glycol, (4-methyl) tetramethylene glycol, (3-ethyl) tetramethylene glycol , (4-ethyl) tetramethylene glycol, (3,3-dimethyl) tetramethylene glycol, (3,3-methylethyl) tetramethylene glycol, (3,3-diethyl) tetramethylene glycol, (4,4-dimethyl) ) Tetramethylene glycol, (4,4-methylethyl) tetramethylene glycol, (4,4-diethyl) tetramethylene glycol and the like.

  As a branched alkylene ether unit represented by the above general formula (II-4), when described as glycol, (3-methyl) pentamethylene glycol, (4-methyl) pentamethylene glycol, (5-methyl) pentamethylene glycol , (3-ethyl) pentamethylene glycol, (4-ethyl) pentamethylene glycol, (5-ethyl) pentamethylene glycol, (3,3-dimethyl) pentamethylene glycol, (3,3-methylethyl) pentamethylene glycol (3,3-diethyl) pentamethylene glycol, (4,4-dimethyl) pentamethylene glycol, (4,4-methylethyl) pentamethylene glycol, (4,4-diethyl) pentamethylene glycol, (5,5 -Dimethyl) pentamethyleneglycol , (5,5-methylethyl) pentamethylene glycol, and the like (5,5-diethyl) pentamethylene glycol.

  As mentioned above, although the alkylene ether unit was described as an example for the sake of convenience, it should be understood that not only these glycols but also these alkylene oxides or these polyether-forming derivatives are described in the same manner.

  Moreover, it is preferable that the terminal group of the above-mentioned polyalkylene glycol polymer or copolymer is a hydroxyl group. However, even if one end or both ends are blocked with alkyl ether, aryl ether, aralkyl ether, etc., or fatty acid ester, aryl ester, etc., there is no effect on the performance, etherified product or ester Compounds can be used as well.

  As the alkyl group constituting the alkyl ether, either linear or branched can be used, and an alkyl group having 1 to 22 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a lauryl group, Preferred examples include stearyl groups such as polyalkylene glycol methyl ether, ethyl ether, butyl ether, lauryl ether, and stearyl ether.

  The aryl group constituting the aryl ether is preferably an aryl group having 6 to 22 carbon atoms, more preferably 6 to 12 carbon atoms, still more preferably 6 to 10 carbon atoms, such as a phenyl group, a tolyl group, or a naphthyl group. And a phenyl group, a tolyl group and the like are preferable. The aralkyl group is preferably an aralkyl group having 7 to 23 carbon atoms, more preferably 7 to 13 carbon atoms, still more preferably 7 to 11 carbon atoms, and examples thereof include a benzyl group and a phenethyl group. Particularly preferred.

The fatty acid constituting the fatty acid ester may be either linear or branched, and may be a saturated fatty acid or an unsaturated fatty acid.
The fatty acid constituting the fatty acid ester is a monovalent or divalent fatty acid having 1 to 22 carbon atoms, such as a monovalent saturated fatty acid, such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid. , Caprylic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid and monounsaturated fatty acids such as oleic acid, elaidic acid, Unsaturated fatty acids such as linoleic acid, linolenic acid, and arachidonic acid, and divalent fatty acids having 10 or more carbon atoms such as sebacic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, tapsiaic acid and decenedioic acid, undecene Diacid, dodecenedioic acid.

  The aryl group constituting the aryl ester is preferably an aryl group having 6 to 22 carbon atoms, more preferably 6 to 12 carbon atoms, and still more preferably 6 to 10 carbon atoms, such as a phenyl group, a tolyl group, or a naphthyl group. And a phenyl group, a tolyl group and the like are preferable. Since the end-capping group is an aralkyl group and exhibits good compatibility with the polycarbonate resin, it can exhibit the same action as an aryl group. The aralkyl group is preferably 7 to 23 carbon atoms, more preferably Is preferably an aralkyl group having 7 to 13 carbon atoms, more preferably 7 to 11 carbon atoms, and examples thereof include a benzyl group and a phenethyl group, and a benzyl group is particularly preferable.

The number average molecular weight of the polyalkylene glycol polymer or copolymer is preferably 200 to 5000, more preferably 300 or more, still more preferably 500 or more, more preferably 4000 or less, and still more preferably 3000 or less. It is. Exceeding the upper limit of the above range is not preferable because the compatibility with the polycarbonate resin decreases, and if it is lower than the lower limit of the above range, gas is generated during molding, which is not preferable.
In addition, the number average molecular weight of a polyalkylene glycol polymer here is a number average molecular weight calculated based on the hydroxyl value measured based on JISK1577.

  Polyalkylene glycol polymers include, among others, homopolymers composed of tetramethylene ether units, trimethylene ether units or 2-methylethylene ether units, copolymers composed of tetramethylene ether units and 2-methylethylene ether units, tetra A copolymer consisting of a methylene ether unit and a 3-methyltetramethylene ether unit, and a copolymer consisting of a tetramethylene ether unit and a 2,2-dimethyltrimethylene ether unit are particularly preferred.

  A preferable content when the polyalkylene glycol polymer or copolymer is contained is 0.1 to 4 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). More preferably, the content is 0.15 parts by mass or more, more preferably 0.2 parts by mass or more, more preferably 3.5 parts by mass or less, still more preferably 3 parts by mass or less, particularly preferably 2.5 parts by mass. Hereinafter, it is most preferably 2 parts by mass or less. When the content is less than 0.1 parts by mass, improvement in hue and yellowing tends to be insufficient, and when it exceeds 4 parts by mass, the transmittance tends to decrease due to white turbidity of the polycarbonate resin, and melt kneading by an extruder. In this case, breakage of the strands is likely to occur frequently, making it difficult to produce pellets.

  Polycarbonate resins are heat stabilizers, antioxidants, mold release agents, UV absorbers, fluorescent brighteners, pigments, dyes, other polymers, flame retardants, impact resistance improvers, antistatic agents, plasticizers, Various additives such as a compatibilizing agent can be contained. These additives may be used alone or in combination of two or more. Among these, it is particularly preferable to use a heat stabilizer and an antioxidant.

  Although there is no restriction | limiting in particular as a heat stabilizer, For example, a phosphorus compound is mentioned preferably. Any known phosphorous compound can be used. Specific examples include phosphorus oxo acids such as phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, polyphosphoric acid, acidic pyrophosphoric acid metal salts such as acidic sodium pyrophosphate, acidic potassium pyrophosphate, acidic calcium pyrophosphate, and phosphoric acid. Examples include Group 1 or Group 10 metal phosphates such as potassium, sodium phosphate, cesium phosphate, and zinc phosphate, organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds.

  Among them, triphenyl phosphite, tris (monononylphenyl) phosphite, tris (monononyl / dinonyl phenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, monooctyl diphenyl phosphite, Dioctyl monophenyl phosphite, monodecyl diphenyl phosphite, didecyl monophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) ) Organic phosphite compounds such as octyl phosphite are preferred. Specific examples of such organic phosphite compounds include, for example, “ADEKA STAB 1178”, “ADEKA STAB 2112”, “ADEKA STAB HP-10” manufactured by ADEKA, “JP-351” manufactured by Johoku Chemical Industry Co., Ltd., “ JP-360 ”,“ JP-3CP ”,“ Irgaphos 168 ”manufactured by BASF, and the like.

  The content of the heat stabilizer is usually 0.001 part by mass or more, preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, based on 100 parts by mass of the polycarbonate resin. It is not more than part by mass, preferably not more than 0.7 part by mass, more preferably not more than 0.5 part by mass. If the amount of the heat stabilizer is too small, the heat stabilization effect may be insufficient. If the amount of the heat stabilizer is too large, the effect may reach a peak and may not be economical.

  Moreover, as an antioxidant, a hindered phenolic antioxidant is mentioned preferably, for example. Specific examples thereof 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] phosphonate, 3,3 ', 3 ", 5,5', 5" -hexa-tert-butyl-a, a ', a -(Mesitylene-2,4,6-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- And bis (octylthio) -1,3,5-triazin-2-ylamino) phenol.

Among them, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate preferable. Specifically, as such a phenolic antioxidant, for example, “Irganox 1010” (registered trademark, the same shall apply hereinafter) manufactured by BASF, “Irganox 1076”, “ADEKA STAB AO-50” manufactured by ADEKA, "ADK STAB AO-60" etc. are mentioned.
In addition, 1 type may contain antioxidant and 2 or more types may contain it by arbitrary combinations and a ratio.

  The content of the antioxidant is usually 0.001 part by mass or more, preferably 0.01 part by mass or more, and usually 1 part by mass or less, preferably 0.5 part by mass with respect to 100 parts by mass of the polycarbonate resin. Or less. When the content of the antioxidant is less than the lower limit of the range, the effect as an antioxidant may be insufficient, and when the content of the antioxidant exceeds the upper limit of the range, There is a possibility that the effect reaches its peak and is not economical.

The pellet of the present invention is a spherical pellet of polycarbonate resin having the above-described viscosity average molecular weight of 10,000 to 19000, the average minor axis of the pellet is 1.5 mm or more, the sphericity is 1 to 1.6, and the bulk density (Measured according to JIS K5101-12-1) is 0.710 g / ml or more.
The spherical pellet does not have to be a perfect spherical shape, and means a substantially spherical shape, a substantially elliptical sphere shape, a substantially egg shape, or the like.

The average minor axis of the pellet is 1.5 mm or more. The minor axis means the shortest diameter of the pellet, and the major axis means the longest diameter of the pellet. Pellets having an average minor axis of less than 1.5 mm have a large specific surface area and are likely to absorb moisture, and haze is likely to occur during molding. A preferable average minor axis is 1.8 mm or more, more preferably 2 mm or more, further preferably more than 2.1 mm, preferably 4 mm or less, more preferably 3.5 mm or less, and further preferably 3 mm or less.
The average major axis of the pellet is preferably 5 mm or less, more preferably 4.5 mm or less, still more preferably 4 mm or less, particularly preferably 3 mm or less, provided that the sphericity is 1 to 1.6. The lower limit is preferably 1.5 mm, more preferably 2 mm, still more preferably 2.5 mm, and particularly preferably 3 mm.
Specifically, the average minor axis and the average major axis are average values obtained from a minor axis value or a major axis value measured for 100 randomly extracted pellets. At this time, in the case of including a continuous sphere in which spherical spheres are connected to each other, each of a plurality of spheres constituting the connected sphere is handled as one pellet for calculation.

  The sphericity of the pellet is 1 to 1.6. Here, the sphericity means the average major axis / average minor axis obtained by dividing the average major axis by the average minor axis. When the sphericity exceeds 1.6, the bulk density tends to increase, and a lot of air is contained between the pellets, so that haze is easily generated during molding. The sphericity is preferably 1.2 or more, more preferably 1.3 or more, and preferably 1.58 or less.

  The pellet of the present invention has a short diameter and a sphericity as described above, and thus has a high bulk density, and the bulk density is 0.710 g / ml or more. Here, the bulk density is measured according to JIS K5101-12-1, and details of the specific measurement method are as described in the examples. The preferred bulk density is 0.715 g / ml or more, more preferably 0.720 g / ml or more, preferably 0.800 g / ml or less, more preferably 0.780 g / ml or less, still more preferably 0.00. 770 g / ml or less, particularly preferably 0.760 g / ml or less, most preferably 0.750 g / ml or less.

  The above-mentioned polycarbonate resin pellet is preferably in a cooling medium in which the above-described polycarbonate resin or polycarbonate resin composition is melt-kneaded with an extruder and then in a mist state of water and air and the temperature is in the range of 95 to 140 ° C. Manufactured by hot cut method with extrusion cutting.

Hereinafter, it will be described with reference to the drawings.
FIG. 1 is a sectional view showing an example of a hot cut system used in the present invention, and FIG. 2 is a side view of the hot cut system of FIG.

First, the polycarbonate resin is sequentially supplied to the extruder 1 by a feeder (quantitative feeder) via a hopper chute installed on the extruder, and melted and kneaded in the extruder 1. As the extruder, a single screw extruder, a twin screw extruder or the like can be used.
When blending other components other than polycarbonate resin, for example, blend all components with a tumbler, Henschel mixer, blender, etc., then feed into the hopper chute via a feeder as necessary and feed to the extruder 1 May be.
The temperature for melt kneading is preferably in the range of 220 to 320 ° C, and preferably in the range of 240 to 300 ° C.

The melt-kneaded polycarbonate resin is extruded from a die 2 provided at the tip of the extruder 1 and cut by a cutter 4 provided on the front surface of the die.
As shown in FIG. 2, the preferred form of the die has a large number of holes 3 provided on the same circumference of the die plate 2, and the hole diameter depends on the extrusion pressure and the desired pellet size. However, the number is about 1 to 5 mm and the number is about 5 to 200.

  A rotary cutter 4 having a plurality of blades having axes at the circumferential center of the die hole 3 is preferably provided on the front surface of the die 2 and is cut into pellets 5 by the cutter 4. The rotary cutter 4 is rotationally driven by a motor 6 connected to a shaft passing through its central shaft, and the rotational speed is usually in the range of 100 to 5000 rpm.

In the method of the present invention, the extrusion of the polycarbonate resin from the die 2 is extruded into a cooling medium having a temperature of 95 to 140 ° C. in a mist state of water and air, and is cut by the cutter 4. Here, the mist state refers to a state in which a mixture of water and air is in a mist state (mist).
The die 2 and the cutter unit are accommodated in a casing 7 called a cutter hood (or cutter case). The inside of the die 2 and the cutter unit are extruded and cut after being made into a mist state of water at 95 to 140 ° C. If the temperature of the mist falls below 95 ° C, the resulting pellet is likely to be deformed and become indeterminate, air bubbles (voids) occur frequently in the pellet, and the amount of chips generated increases, resulting in a mist temperature. When the temperature exceeds 140 ° C., the resulting pellets tend to adhere to each other and form a continuous ball, and the amount of chips generated is significantly increased. The temperature of the mist is preferably 95 to 135 ° C.

In order to make such a mist state, as shown in FIG. 2, preheated water and air are injected in the direction of the arrow from the cooling medium inlets 8 and 9 provided in the casing, and the casing together with the pellets 5 obtained. It discharges from the lower discharge port 10. The temperature of the heated water to be injected is preferably 60 to 95 ° C, more preferably 65 to 95 ° C, particularly 70 to 95 ° C, and the heated air to be injected is preferably 150 ° C or higher, more preferably 170 ° C. More preferably, the temperature is 180 ° C. or higher, preferably 500 ° C. or lower, more preferably 400 ° C. or lower, further 300 ° C. or lower, and particularly preferably 250 ° C. or lower.
In addition, the proportion of water in water and air is preferably 0.1% or more and 100% or less, more preferably 0.1% or more and less than 100%. Furthermore, it is preferably 0.1% or more and 50% or less, more preferably 0.1% or more and 20% or less, particularly 0.1% or more and 10% or less, and particularly preferably 0.1% or more and 7% or less.
Further, the pressure of the mist-like cooling medium may be normal pressure or in a pressurized state.

  The pellets 5 obtained by cutting are discharged from the discharge port 10 of the casing 7 together with the cooling medium, guided to a dehydrating device, and dried to obtain pellets.

The polycarbonate resin pellet obtained by the method of the present invention has a feature that bubbles are hardly generated inside. Here, the bubble refers to a bubble (including a vacuum) enclosed in the pellet, and is also referred to as a void.
The degree of bubble generation can be expressed as a percentage (n / 100) of the number n of pellets containing bubbles by visually observing 100 randomly selected from the obtained pellets, In the present invention, the bubble generation rate (%) is preferably 20% or less, more preferably 15% or less, further preferably 10% or less, and particularly 5% or less.

The pellets of the present invention or the polycarbonate resin pellets obtained by the method of the present invention are molded into an arbitrary shape and used as a molded body. There is no restriction | limiting in the shape of a molded object, a pattern, a color, a dimension, etc., What is necessary is just to set arbitrarily according to the use of the molded object.
The manufacturing method of a molded object is not specifically limited, The molding method generally employ | adopted about polycarbonate resin can be employ | adopted arbitrarily. For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, hollow molding method such as gas assist, molding method using heat insulating mold, rapid heating mold were used. Molding method, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding method, extrusion molding method, sheet molding method, thermoforming method, rotational molding method, laminate molding method, press molding method, etc. Is mentioned. A molding method using a hot runner method can also be used.

  In particular, the pellets of the present invention or the polycarbonate resin pellets obtained by the method of the present invention are less likely to generate chips, have no internal voids, have a high bulk density, and have a high filling rate at the time of molding. Therefore, it is useful for parts such as electric and electronic equipment, OA equipment, and cameras as a thin molded product.

  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.

[Example 1]
A polycarbonate resin having a viscosity average molecular weight Mv of 13000 containing 0.02% by mass of a stabilizer (tris (2,4-di-tert-butylphenyl) phosphite, manufactured by ADEKA, trade name “ADK STAB 2112”) It was melt-kneaded with a twin screw extruder “TEM37BS” manufactured by Kikai Co., Ltd., and pelletized with a hot cut system manufactured by CTE Inc.
The extrusion conditions were a discharge rate of 20 kg / hr, a screw rotation speed of 200 rpm, a cylinder set temperature, a flange and die set temperature of 240 ° C. A rotary cutter having 10 holes, a hole diameter of 3 mm, and two blades was used. The cutter speed was 1000 rpm. The molten resin that came out of the die was extruded and cut into a cooling medium in a mist state of water and air.
That is, water was heated to 90 ° C. through a steam pipe at 1 l / min and supplied to the hot cut system. On the other hand, the pressure of the air is increased to 0.5 MPa by a compressor, lowered to 0.2 MPa by a regulator, passed through “Hot Air Beam Type E” (9 kW) manufactured by Yako Electric Co., Ltd. at a flow rate of 200 l / min, and heated to 180 ° C. And supplied to the hot cut system. It was confirmed that water and air became mist in the hot cut system and covered the dice and cutter. The temperature of the mist was 127 ° C. as measured with a thermocouple.

  The shape of the pellets coming out of the hot cut system was spherical with high sphericity. The bulk density of the obtained pellet was measured with a bulk density measuring device based on JIS K5101-12-1. Specifically, it was measured using a multifunctional powder physical property measuring instrument “Multi Tester MT-1001K” manufactured by Seishin Co., Ltd. The pellet was gently filled into a 100 g cell, and the pellet from the cell was scraped with a scraping plate, and the weight of the pellet contained in the container was determined to obtain the bulk density.

  Further, 100 samples randomly selected from the obtained pellets were visually observed, but there were no pellets containing bubbles, and the generation rate of the bubble-containing pellets was 0% (0/100). Moreover, the average weight of one pellet was 16 mg. The minor axis and major axis of the 100 pellets were measured, and the average minor axis, average major axis and sphericity were determined. The average minor axis was 2.5 mm, the average major axis was 3.5 mm, and the sphericity was 1.40.

  Moreover, the obtained pellet was dried, 500 g was put into a 2 L polyethylene container, put into a tumbler “SKD50” manufactured by Seiwa Iron Works, Inc., fixed, and then stirred for 120 minutes to generate chips. . The total amount of pellets and chips in the container was put into 1 L of a 1/1 mixed solvent of water and ethanol, and the mixture was lightly stirred and filtered to obtain chips with a particle size of 10 μm to 1000 μm. The amount of chips generated was 11.5 mg. That is, 23 ppm of chips were generated with respect to the pellets.

Furthermore, a 61 mm × 112 mm × 0.6 mm thin plate was molded from the obtained pellets using a Sodic “HSP100A” molding machine. The molding conditions were a resin temperature of 320 ° C., a mold temperature of 40 ° C., an injection speed of 1000 mm / second, a holding pressure of 40 MPa, 8 seconds, and a molding cycle of 30 seconds. The molded plate was visually confirmed, but there was no haze.
It is known that haze occurs when there are usually bubbles in the pellet or when the shape of the pellet is irregular. On the other hand, there was no haze and the result was good.
The evaluation results are shown in Table 1 below.

[Examples 2 to 6]
In Example 1, pellets were produced in the same manner as in Example 1 except that the temperature and amount of water to be supplied and the temperature and amount of supplied air were set to the values described in Table 1 below. In the same manner, the shape, bulk density, short diameter, long diameter, sphericity, bubble generation rate, chip generation amount, and the presence or absence of haze of the molded plate were evaluated. The results are shown in Table 1 below.

[Examples 7 to 10]
In Example 1, the polycarbonate resin used was changed to one having the viscosity average molecular weight (Mv) described in Table 1, and the temperature and amount of water to be supplied and the temperature and amount of air to be supplied were described in Table 1 below. Except for the values, pellets were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1 below.

[Example 11]
A homopolymer composed of (2-methyl) ethylene ether unit having a number average molecular weight Mn of 1000 (polypropylene glycol (PPG), manufactured by NOF Corporation, product name “100 parts by weight” of a polycarbonate resin having a viscosity average molecular weight Mv of 13000. Uniol D-1000 ") 0.7 parts by mass, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (manufactured by ADEKA, trade name" ADK STAB PEP-36 ") Pellets were produced from the polycarbonate resin containing 0.05 part by mass in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

[Example 12]
A homopolymer composed of tetramethylene ether units having a number average molecular weight Mn of 1000 (polytetramethylene glycol (PTMG), manufactured by Mitsubishi Chemical Corporation, trade name “PTMG1000”) with respect to 100 parts by mass of a polycarbonate resin having a viscosity average molecular weight Mv of 13000 ) 1.0 part by mass, 0.02 part by mass of bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (manufactured by ADEKA, trade name “ADK STAB PEP-36”) And a polycarbonate resin containing 0.03 parts by mass of 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexylcarboxylate (manufactured by Daicel, trade name “Celoxide 2021P”) in the same manner as in Example 1. The pellets were manufactured by the method and evaluated in the same manner as in Example 1. It was. The evaluation results are shown in Table 2 below.

[Example 13]
Copolymer (PTMG-PPG copolymer, manufactured by NOF Corporation) consisting of tetramethylene ether unit and 2-methylethylene ether unit having number average molecular weight Mn of 1000 with respect to 100 parts by mass of polycarbonate resin having viscosity average molecular weight Mv of 13000 , 1.0 part by mass of trade name “polyserine DCB-1000”) and 0.03 part by mass of tris (2,4-di-tert-butylphenyl) phosphite (trade name “ADK STAB AS2112” manufactured by ADEKA) Pellets were produced from the contained polycarbonate resin in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

[Example 14]
Homopolymer consisting of (2-ethyl) ethylene ether unit having a number average molecular weight Mn of 500 (polybutylene glycol (PBG), manufactured by NOF Corporation, product name) with respect to 100 parts by mass of a polycarbonate resin having a viscosity average molecular weight Mv of 16000 0.6 part by mass of “Uniol PB-500”), bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name “ADK STAB PEP-36” manufactured by ADEKA) 0.02 part by mass, 0.1 part by mass of tris (2,4-di-tert-butylphenyl) phosphite (manufactured by ADEKA, trade name “ADEKA STAB AS2112”), and 3,4-epoxycyclohexylmethyl- 3 ′, 4′-epoxycyclohexylcarboxylate (Daicel, trade name “Celoxide 2” 0.05 parts by weight containing polycarbonate resin 21P "), to prepare pellets in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

[Example 15]
A homopolymer consisting of a (2-ethyl) ethylene ether unit having a number average molecular weight Mn of 700 (polybutylene glycol (PBG), manufactured by NOF Corporation, trade name “Uniol” with respect to 100 parts by mass of a polycarbonate resin having a viscosity average molecular weight Mv of 16000. 0.6 parts by mass of PB-700 ") and 0 of bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (trade name" ADK STAB PEP-36 "manufactured by ADEKA) 0.02 part by mass, 0.1 part by mass of tris (2,4-di-tert-butylphenyl) phosphite (manufactured by ADEKA, trade name “ADK STAB AS2112”), and 3,4-epoxycyclohexylmethyl-3 ′ , 4'-epoxycyclohexylcarboxylate (manufactured by Daicel Corporation, trade name “Celoxide 20 0.05 parts by weight containing polycarbonate resin 1P "), to prepare pellets in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

[Comparative Example 1]
Pellets were produced in the same manner as in Example 1 except that the water temperature was 50 ° C. and the air temperature was 80 ° C. The mist temperature was 62 ° C. Evaluation was performed in the same manner as in Example 1.
The obtained pellets were amorphous. Of 100 randomly selected pellets, 82 pellets contained bubbles (bubble generation rate: 82%). The amount of chips generated was 128 ppm. The evaluation results are shown in Table 3 below.

[Comparative Examples 2-3]
Pellets were produced in the same manner as in Example 1 except that the temperature of the supplied air was changed to the values described in Table 2 below, and the same evaluation as in Example 1 was performed. In Comparative Example 3, only a continuous spherical shape was obtained. The evaluation results are shown in Table 3 below.

[Comparative Example 4]
In Example 1, pellets were produced in the same manner as in Example 1 except that the polycarbonate resin used was changed to that having the viscosity average molecular weight (Mv) described in Table 2, and the same evaluation as in Example 1 was performed. It was. The evaluation results are shown in Table 3 below.

[Comparative Example 5]
In Example 1, after changing the die to one having a hole diameter of 1 mm, pellets were produced and carried out in the same manner as in Example 1 except that the extrusion condition was 5 kg / hr and the cutter speed was 3000 rpm. Evaluation similar to Example 1 was performed. The evaluation results are shown in Table 3 below.

[Comparative Example 6 (Strand Cut Method)]
The strand extruded from the die in Example 1 was passed through a cooling water bath having a temperature of 52 ° C. as it was, and then the strand was cut with a pelletizer. The obtained pellets were cylindrical and the bubble generation rate was 100%. The amount of chips generated was 257 ppm.
The results are shown in Table 3 below.

  The pellets of the present invention or the polycarbonate resin pellets obtained by the method of the present invention are less likely to generate chips, have no internal voids, have a high bulk density, and have a high filling rate at the time of molding. Therefore, taking advantage of these features, it can be suitably used for parts such as electric and electronic equipment, OA equipment, cameras, etc., and industrial applicability is very high.

1 Extruder 2 Dies 3 Die Holes 4 Cutter 5 Pellet 8, 9 Cooling Medium Injection Port

Claims (5)

  A polycarbonate resin having a viscosity average molecular weight of 10,000 to 19000 is melt-kneaded by an extruder, and then extruded and cut into a cooling medium having a temperature of 95 to 140 ° C. in a mist state of water and air. A method for producing polycarbonate resin pellets. The method for producing a polycarbonate resin pellet according to claim 1 , wherein the cooling medium is a mist of water and air having a volume ratio of water of 0.1% to 100%. The method for producing a polycarbonate resin pellet according to claim 1 or 2 , wherein the cooling medium is a mist of water and air having a volume ratio of water of 0.1% or more and less than 100%. The polycarbonate resin pellet is a spherical pellet, the average minor axis of the pellet is 1.5 mm or more, the sphericity is 1 to 1.6, and the bulk density (measured according to JIS K5101-12-1) is 0. The method for producing polycarbonate resin pellets according to any one of claims 1 to 3, wherein the production method is 710 g / ml or more. The bulk density of a polycarbonate resin pellet is 0.730 g / ml or more, The manufacturing method of the polycarbonate resin pellet in any one of Claims 1-4.