JP2003285320A - Manufacturing method for polyarylate resin pellet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing polyarylate resin pellets by cooling strands extruded from an extruder in a molten state without generating air bubbles in the strands to cut the cooled strands by a pelletizer. <P>SOLUTION: In the method for manufacturing polyarylate resin pellets by cooling the strands of a polyarylate resin held to a molten state in a water tank and cutting the cooled strands, the strands in the molten state are immersed in the water tank of which the temperature is held to a temperature lower than the glass transition temperature of the polyarylate resin by 100-120°C, and cooled at a cooling speed of 60°C/s or less until the surface temperature of the strands becomes lower than the glass transition temperature of the polyarylate resin by 10-50°C. After the surface temperature is held for 2 sec or more, the strands are cut to manufacture polyarylate resin pellets. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing pellets of polyarylate resin, more specifically, it is difficult to generate air bubbles in pellets of polyarylate resin, and to reduce fine powder and chips contained therein. The present invention relates to a method for producing pellets in which a defective appearance due to silver or the like when molded is not generated.

[0002]

2. Description of the Related Art Polyarylate composed of residues of 2,2-bis (4-hydroxyphenyl) propane (sometimes referred to as bisphenol A) and residues of terephthalic acid and isophthalic acid is already well known as an engineering plastic. Has been. Such polyarylate has high heat resistance, excellent mechanical strength typified by impact strength, and dimensional stability. In addition, since it is amorphous and transparent, its molded product is used in fields such as electric / electronic, automobile, and machine. Widely applied to.

The production method thereof includes a solution polymerization method, an interfacial polymerization method, a melt polymerization method, and the like, and those polymers are mainly powdery obtained by the solution polymerization method or the interfacial polymerization method. Gives pellets. The shape of the polymer thus obtained varies depending on the polymerization method, but even when the polymer is obtained in the form of powder due to handling problems, it is often further melted and pelletized. Further, in order to obtain a composition obtained by modifying the polyarylate, it is often the case that other polymers, various compounding agents and the like are kneaded in a molten state and then pelletized. In such cases. In the step of pelletizing the polyarylate resin, the polymer or composition is extruded in the form of a strand from an extruder, and the strand is cooled by dipping it in a water tank or directly spraying water, and then cut into a predetermined length. Methods have been used. Generally, a method of rapidly cooling a strand using a water tank and cutting it with a pelletizer is often used.

When the cooled strand of polyarylate resin is cut with a pelletizer or the like, fine powder is often generated and pellets are cracked or chipped. If these pieces are used in a state of being mixed with normal pellets, there arise problems such as generation of dust in a supply section such as a hopper and adhesion of dust inside the apparatus due to static electricity. Therefore, in the present situation, it is necessary to introduce a step of removing fine powder or pellet fragments in the pelletizing step or the subsequent pellet packing step. Further, when a pelletized resin is used when forming a pelletized resin, there is a problem that silver is generated and the appearance of the molded article is impaired. Silver is a phenomenon in which when a resin is filled in a mold in injection molding, air entrained when the resin is melted or gas generated from the molten resin appears as streaks on the surface portion of the resin. These problems are the same when pelletizing polycarbonate resin,
In JP 2001-269929 A, the production of aromatic polycarbonate pellets is controlled in a water tank of a plurality of stages while controlling the surface temperature of the strands to fall within a specific range, thereby suppressing the runout of the strands, and further pellets. A method for solving the above problems by suppressing the generation of bubbles in the inside has been proposed.

However, since polyarylate has poorer fluidity when melted than general polycarbonate, it is necessary to raise the melting temperature in an extruder and, in addition, the glass transition temperature is high, so that the effect described in the above publication is obtained. Is difficult to obtain. That is, when the strand of the polyarylate resin is cooled by the method described in the above-mentioned publication, the vibration of the strand when immersed in a water tank is suppressed, but the generation of bubbles in the strand is hardly suppressed, and bubbles are obtained in the resulting pellets. In addition to being left behind, when the strand was cut with a pelletizer, large air bubble portions in the strand were broken, and a large amount of pellet fragments were generated.

[0006]

In view of the above situation, an object of the present invention is to cool a strand melt-extruded by an extruder without generating bubbles therein and cut it with a pelletizer. It is to provide a method for producing polyarylate resin pellets.

[0007]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that a molten polyarylate resin strand is cooled by bringing it into contact with water and then cut into pellets. In the method of making, the temperature of the water is maintained in a specific range where the molten strand is contacted, the temperature of the strand is cooled at a specific cooling rate until it falls within a specific range, and the temperature is maintained for a predetermined period of time. Based on this finding, the present invention was reached based on the finding that when cut, not only bubbles do not occur in the strand, but also cracks and chips in the pellet that occur during cutting are significantly reduced. That is, according to the present invention, in a method for producing a polyarylate resin pellet by cooling a molten polyarylate resin strand in a water tank, the temperature is 100 to 120 from the glass transition temperature of the polyarylate resin.
The molten strand is immersed in a water bath maintained at a temperature lower than ℃, and the surface temperature of the strand is lower than the glass transition temperature of the polyarylate resin at a cooling rate of 60 ° C / sec or less.
Cool down to ~ 50 ° C, and increase the surface temperature to 2
The gist is a method for producing a polyarylate resin pellet, which is characterized in that the strand is cut after being held for a second or more.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the method for producing the polyarylate resin pellets of the present invention will be described in detail. The polyarylate of the present invention is an amorphous aromatic polyester substantially composed of a dihydric phenol and an aromatic dicarboxylic acid. What is used as the dihydric phenol component constituting the polyarylate resin of the present invention is 4,4′-dihydroxybiphenyl, 2-methyl-4,4′-dihydroxybiphenyl, 3-methyl-4,4′-dihydroxybiphenyl. , 2-chloro-4,4'-dihydroxybiphenyl, 3-chloro-4,4'-dihydroxybiphenyl, 3,3'-dimethyl-4,4'-dihydroxybiphenyl, 2,2'-dimethyl-4,4 '-Dihydroxybiphenyl, 2,3'-dimethyl-4,4'-dihydroxybiphenyl, 3,3'-dichloro-4,4'-dihydroxybiphenyl, 3,3'-di-tert-butyl-4,4' -Dihydroxybiphenyl, 3,3'-dimethoxy-4,4'-dihydroxybiphenyl, 3,
3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl, 3,3', 5,5'-tetra-tert
-Butyl-4,4'-dihydroxybiphenyl, 3,
3 ', 5,5'-tetrachloro-4,4'-dihydroxybiphenyl, 2,2'-dihydroxy-3,3'-dimethylbiphenyl, 3,3'-difluoro-4,4'-
Biphenol, 2,2'-dihydroxy-3,3 ',
5,5'-tetramethylbiphenyl, 3,3 ', 5,
5'-tetrafluoro-4,4'-biphenol, 2,
2 ', 3,3', 5,5'-hexamethyl-4,4'-
Biphenol, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane,
Bis (4-methyl-2-hydroxyphenyl) methane,
Bis (3,5-dimethyl-4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) -4-
Methyl pentane, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (3-methyl-4-)
Hydroxyphenyl) propane, 2,2-bis (3.5
-Dimethyl-4-hydroxyphenyl) propane, 1,
1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -2-
Ethylhexane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, bis (3-methyl-4-)
Hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) -2-methylpropane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl) octane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 2,2
-Bis (3-allyl-4-hydroxyphenyl) propane, 2,2-bis (3-isopropyl-4-hydroxyphenyl) propane, 2,2-bis (3-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (3-sec-butyl-4-hydroxyphenyl) propane, 1,1-bis (2-methyl-4-hydroxy-)
5-tert-butylphenyl) -2-methylpropane, 4,4 ′-[1,4-phenylene-bis (1-methylethylidene)] bis (3-methyl-4-hydroxyphenyl), 1,1-bis (3-phenyl-4-hydroxyphenyl) cyclohexane, bis (2-hydroxyphenyl) methane, 2,4′-methylenebisphenol,
Bis (3-methyl-4-hydroxyphenyl) methane,
1,1-bis (4-hydroxyphenyl) propane,
1,1-bis (2-hydroxy-5-methylphenyl)
Ethane, 1,1-bis (4-hydroxyphenyl) -3
-Methyl-butane, bis (2-hydroxy-3,5-dimethylphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclo Pentane, 3,3
-Bis (4-hydroxyphenyl) pentane, 3,3-
Bis (3-methyl-4-hydroxyphenyl) pentane, 3,3-bis (3,5-dimethyl-4-hydroxyphenyl) pentane, 2,2-bis (2-hydroxy-)
3,5-Dimethylphenyl) propane, 2,2-bis (4-hydroxyphenyl) nonane, 1,1-bis (3
-Methyl-4-hydroxyphenyl) -1-phenylethane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) decane, 1,1- Bis (4-hydroxyphenyl) decane, 1,1-bis (2-hydroxy-
3-tert-butyl-5-methylphenyl) methane,
Bis (4-hydroxyphenyl) diphenylmethane, terpene diphenol, 1,1-bis (3-tert-butyl-4-hydroxyphenyl) cyclohexane, 1,
1-bis (2-methyl-4-hydroxy-5-tert
-Butylphenyl) -2-methylpropane, 2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane, bis (3,5-di-tert-butyl-4-hydroxyphenyl) methane, bis (3,3 5-di-sec
-Butyl-4-hydroxyphenyl) methane, 1,1-
Bis (3-cyclohexyl-4-hydroxyphenyl)
Cyclohexane, 1,1-bis (2-hydroxy-3,
5-di-tert-butylphenyl) ethane, 1,1-
Bis (3-nonyl-4-hydroxyphenyl) methane,
2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 1,1-bis (2-hydroxy-3,5-di-tert-butyl-6-methylphenyl) methane, 1,1-bis (3-phenyl-4-hydroxyphenyl) -1-phenylethane, α, α′-
Bis (4-hydroxyphenyl) acetic acid butyl ester,
1,1-bis (3-fluoro-4-hydroxyphenyl) methane, bis (2-hydroxy-5-fluorophenyl) methane, 2,2-bis (3-fluoro-4-hydroxyphenyl) propane, 1,1 -Bis (3-fluoro-4-hydroxyphenyl) -1-phenylmethane,
1,1-bis (3-fluoro-4-hydroxyphenyl) -1- (p-fluorophenyl) methane, 1,1-
Bis (4-hydroxyphenyl) -1- (p-fluorophenyl) methane, 2,2-bis (3-chloro-4-hydroxy-5-methylphenyl) propane, 2,2-bis (3,5-dichloro) -4-hydroxyphenyl) propane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (3,5-dibromo-4)
-Hydroxyphenyl) methane, 2,2-bis (3,5)
-Dibromo-4-hydroxyphenyl) propane, 2,
2-bis (3-nitro-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) dimethylsilane, bis (2,3,5-trimethyl-4-hydroxyphenyl) -1-phenylmethane, 2,2- Bis (4-hydroxyphenyl) dodecane, 2,2-bis (3-methyl-4-hydroxyphenyl) dodecane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) dodecane, 1,1-bis (3-tert-butyl-4-hydroxyphenyl) -1-phenylethane, 1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) -1-phenylethane, 1,1-bis (2-Methyl-4-hydroxy-5-cyclohexylphenyl)-
2-methylpropane, 1,1-bis (2-hydroxy-
3,5-di-tert-butylphenyl) ethane, 2,
2-bis (4-hydroxyphenyl) propanoic acid methyl ester, 2,2-bis (4-hydroxyphenyl) propanoic acid ethyl ester, 2,2 ′, 3,3 ′, 5
5'-hexamethyl-4,4'-biphenol, bis (2-hydroxyphenyl) methane, 2,4'-methylenebisphenol, 1,2-bis (4-hydroxyphenyl) ethane, 2- (4-hydroxyphenyl) -2-
(2-Hydroxyphenyl) propane, bis (2-hydroxy-3-allylphenyl) methane, 1,1-bis (2-hydroxy-3,5-dimethylphenyl) -2-
Methyl propane, 1,1-bis (2-hydroxy-5-
tert-Butylphenyl) ethane, bis (2-hydroxy-5-phenylphenyl) methane, 1,1-bis (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, bis (2-methyl-4) -Hydroxy-5-cyclohexylphenyl) methane, 2,2-bis (4-hydroxyphenyl) pentadecane, 2,2-bis (3-methyl-4-hydroxyphenyl) pentadecane, 2,2-bis (3,5-) Dimethyl-4-hydroxyphenyl) pentadecane, 1,2-bis (3,5-di-
tert-butyl-4-hydroxyphenyl) ethane,
Bis (2-hydroxy-3,5-di-tert-butylphenyl) methane, 2,2-bis (3-styryl-4-)
Hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1- (p-nitrophenyl) ethane, bis (3,5-difluoro-4-hydroxyphenyl) methane, bis (3,5-difluoro-) 4-hydroxyphenyl) -1-phenylmethane, bis (3,5-difluoro-4-hydroxyphenyl) diphenylmethane, bis (3-fluoro-4-hydroxyphenyl) diphenylmethane, 2,2-bis (3-chloro-4) -Hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (4-hydroxyphenyl)
-3,3-Dimethyl-5,5-dimethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3
-Dimethyl-4-methyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5
-Ethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclopentane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) -3, 3-dimethyl-5-methyl-
Cyclohexane, 1,1-bis (3,5-diphenyl-
4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (3-methyl-4)
-Hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (3-phenyl-4)
-Hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (3,5-dichloro-4-hydroxyphenyl) -3,3-dimethyl-5-
Methyl-cyclohexane, 1,1-bis (3,5-dibromo-4-hydroxyphenyl) -3,3-dimethyl-
5-methyl-cyclohexane, 1,4-di (4-hydroxyphenyl) -p-menthane, 1,4-di (3-methyl-4-hydroxyphenyl) -p-menthane, 1,4
-Di (3,5-dimethyl-4-hydroxyphenyl)-
Examples thereof include terpene diphenols such as p-menthane.

Of these, 2,2-bis (4-hydroxyphenyl) propane is preferably used. These dihydric phenols may be used alone or in combination of two or more. In addition, a part of the dihydric phenol is converted into ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, dodecanediol, neopentyl glycol, cyclohexanediol, 1,4-dihydroxymethylcyclohexane, etc. It may be replaced with a dihydric alcohol.

Further, examples of the aromatic dicarboxylic acid component constituting the polyarylate of the present invention include terephthalic acid, isophthalic acid, phthalic acid, methyl group, ethyl group, n
-Phthalic group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group and the like, phthalic acid derivatives substituted with 1 or 2 alkyl groups, 1,5-
Naphthalenedicarboxylic acid derivatives such as naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-
Examples include dicarboxybiphenyl, diphenic acid, 4,4′-dicarboxydiphenyl ether, bis (p-carboxyphenyl) alkane, 4,4′-dicarboxydiphenyl sulfone, and the like, or a mixture of one or more of these. May be used. Among these, terephthalic acid and isophthalic acid are preferable, and a mixture of terephthalic acid and isophthalic acid is particularly preferable. The aromatic dicarboxylic acid component may be used as a free aromatic dicarboxylic acid or an aromatic dicarboxylic acid dihalide.

In the present invention, a part of the above-mentioned aromatic dicarboxylic acid may be replaced with another aliphatic dicarboxylic acid as long as the characteristics thereof are not substantially impaired. Examples of such dicarboxylic acid include dicarboxymethylcyclohexane, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, glutaric acid and dodecanedioic acid. The above-mentioned dihydric phenol and divalent aromatic carboxylic acid may be used as a copolymer of two or more kinds, or may be one other than those exemplified above.

In the present invention, the terminal of the polyarylate molecule is, in addition to phenol, o, m, p-cresol, dimethylphenol, o, m, p-ethylphenol, o,
m, pn-propylphenol, o, m, p-isopropylphenol, o, m, pn-butylphenol, o, m, p-isobutylphenol, o, m, p-
Monohydric phenol such as sec-butylphenol, o, m, p-tert-butylphenol, and one of methanol, ethanol, n-propanol, isopropanol, butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, phenethyl alcohol, etc. Monovalent carboxylic acids such as dihydric alcohol and acetic acid, propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, p-methoxyphenylacetic acid, benzoic acid chloride, It may be blocked with acid chlorides such as methanesulfonyl chloride and phenyl chloroformate.

Next, the method for producing the polyarylate resin pellets of the present invention will be described in more detail. The polyarylate to which the method of the present invention is applied can be produced by a melt polymerization method or an interfacial polymerization method. In the melt polymerization method, for example, an acetylated bisphenol and an aromatic dicarboxylic acid are optionally used as a Lewis acid or the like. High temperature in the presence of
It is produced by polymerization under reduced pressure. However, in this case, the resulting polymer is often colored. In the interfacial polymerization method, for example, an organic solvent solution prepared by dissolving terephthalic acid and / or isophthalic acid as an acid halide in an organic solvent incompatible with water, a dihydric phenol compound, and optionally the above-mentioned end capping agent together These two solutions are mixed and stirred in the coexistence of the dissolved alkaline aqueous solution and the polymerization catalyst to produce polyarylate. In this case, a polymer having a high degree of polymerization and little coloring can be obtained. The polyarylate used in the present invention is preferably polymerized by an interfacial polymerization method.

A general interfacial polymerization method for polyarylate is to use an alkaline aqueous solution in which a dihydric phenol compound is dissolved in the presence of a polymerization catalyst, and optionally an alkaline aqueous solution in which the above-mentioned terminal blocking agent is also dissolved. Mixing methylene chloride solution of dicarboxylic acid dihalide, 2 ~ 50 ℃
The reaction is carried out by reacting the dihydric phenol with the aromatic dicarboxylic acid dihalide with stirring for 0.5 to 5 hours.

The amount of methylene chloride at the time of interfacial polymerization is preferably used so that the polymer concentration is usually 5 to 25% by mass, more preferably 10 to 25% by mass. If the polymer concentration exceeds 25% by mass, the polymer may be gelled and precipitated during the polymerization. It is difficult to deactivate the active terminals such as acid halide groups in the gelled polymer, and such a polymer adversely affects the color tone during molding. The amount of alkaline water is usually 1 to 3 times the volume of methylene chloride.
Examples of the alkali used during the reaction include sodium hydroxide and potassium hydroxide.

Further, as a polymerization catalyst, trimethylamine, triethylamine, tri-n-butylamine, tri-n-propylamine, tri-isopropylamine, trihexylamine, tridecylamine, N, N-dimethylcyclohexylamine, pyridine, quinoline, Tertiary amines such as dimethylaniline, trimethylbenzylammonium halide, tetramethylbenzylammonium halide, triethylbenzylammonium halide, tri-n-butylbenzylammonium halide,
Quaternary ammonium salts such as tetra-n-butylammonium halide, trimethylbenzylphosphonium halide, tetramethylbenzylphosphonium halide, triethylbenzylphosphonium halide, tri-n-butylbenzylphosphonium halide, tetra-n-butylphosphonium halide, tri Quaternary phosphonium salts such as phenylbenzylphosphonium halide and tetraphenylphosphonium halide, 18-crown-6, 1
8-benzocrown-6,18-dibenzocrown-
Examples thereof include crown ethers such as 6,15-crown-5, and in particular, a quaternary ammonium salt is preferable in terms of polymerization rate and price.

Next, after the interfacial polymerization is completed, an acid is added to stop and neutralize the reaction, and an aqueous phase containing salts and unreacted monomers and a methylene chloride phase in which polyarylate is dissolved are allowed to stand and are separated in a centrifuge or a centrifuge. Separation is performed using a conventionally known method such as a separator. The acid used at this time is preferably hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid or the like. Further, it is preferable to wash the methylene chloride phase with water to remove residual salts and monomers.

In the interfacial polymerization method of polyarylate, an antioxidant such as a hindered phenol compound, a phosphorous acid compound, a hindered amine compound or a thioether compound, an additive such as a colorant is polymerized or washed with water. It is also possible to obtain a polyarylate containing various additives by adding it to a methylene chloride solution.

The polyarylate resin used in the present invention is obtained by isolating the polymer component from the thus obtained methylene chloride solution of polyarylate by a known method. This polymer component is isolated by a reprecipitation method in which a large excess amount of a poor solvent is added to a methylene chloride solution to precipitate the polymer component, and the methylene chloride solution is heated in a grinder at normal pressure or under reduced pressure to remove the solvent. To remove the solvent to produce a polyarylate powder, a spray-drying method to spray a methylene chloride solution to distill off the solvent to produce a fine-particle powder, and put the methylene chloride solution into warm water above the boiling point of the solvent. Then, the solvent is distilled off to obtain a granular polyarylate. Among these, the hot water method is preferable because a polyarylate resin excellent in handleability can be obtained with a relatively simple apparatus.

The number average molecular weight of the polyarylate used in the method of the present invention is 5000 in terms of polystyrene measured by gel permeation chromatography.
The above is preferably 10,000 to 200,000.
If the molecular weight is less than 5,000, the mechanical properties of the polymer will deteriorate, while if it exceeds 200,000, the fluidity during melt extrusion and the processability during molding will deteriorate, which is not preferable.

In a general isolation method of polyarylate from a methylene chloride solution, the particles have a non-uniform shape, or even the uniform shape has an extremely small particle size,
In many cases, the bulk density is low, and the handling property is often problematic. Therefore, the polyarylate resin isolated from the methylene chloride solution is not subjected to molding processing such as injection molding in its original shape, and is often melt extruded by an extruder and re-granulated into pellet form. Alternatively, melt extrusion with an extruder is performed for the purpose of alloying with other polymers for the purpose of modifying the polyarylate, and for adding polymer compounding agents such as stabilizers, ultraviolet absorbers, release agents, and colorants. You may be told. The present invention is applied to these cases.

The extruder used in the present invention is not particularly limited as long as it can melt and further knead a polyarylate resin to extrude it into a strand form, but a twin-screw extruder is preferable, and a raw material during melt kneading is used. It is more preferable to have a vent portion for removing volatile components contained in the resin. The rotation directions of the screws of the twin-screw extruder may be the same or different. In addition, when the vent portion is provided, the number of vents is not particularly limited, but one having 1 to 5 stages of vents is often used. It is usual to supply the polyarylate resin, other polymers, compounding agents for various polymers, etc. to the extruder at the most base side, but in order to change the kneading state of the resin or the compounding agent for polymers. In order to avoid sucking into the vent of the extruder, it is possible to provide one or more side feeders in the middle of the extruder and supply a part of the raw material components or all of the specific components from there.

When the polyarylate resin is extruded in a molten state as a strand from a die of an extruder, the cross-sectional shape of the strand is usually circular, but may be elliptical or polygonal. Strand diameter is 1.5-4.0m
m, preferably 1.7 to 3.5 mm. The diameter of the strand corresponds to the thickness of the product pellet. If it is smaller than 1.5 mm, the strand is likely to be cooled, but it is not preferable because an error may occur in measuring the raw material during processing such as molding. If it exceeds 4.0 mm, it is not preferable because the strand is hard to be cooled and bubbles are likely to be generated in the center part, or "beard" which causes dust at the time of cutting is easily generated. The temperature of the molten strand extruded from the extruder varies depending on the type of polyarylate resin, the type of other polymer to be alloyed, and the properties of the resin composition, but is usually 240 to 390 ° C., preferably 260 to 390 ° C.
370 ° C.

The strands of polyarylate resin extruded in the extruder are then introduced into the cooling process. This cooling step includes a method of immersing the strand in a water tank and a method of spraying water on the strand while the strand is taken from the extruder to the cutting step. In the present invention, either method may be used, but the cooling temperature and cooling rate of the strand are important points.

One of the important points of the present invention is that the temperature of the water which the molten strand contacts is 100 to 120 ° C., preferably 105 to 115 ° C. below the glass transition temperature of the polyarylate resin. is there. This temperature varies depending on the type and properties of polyarylate, but as an absolute value, it is usually 50 to 95 ° C., preferably 60 to 90.
It is selected from the range of ° C. Maintaining this water temperature is important for reducing the cooling rate of the strand. When the water temperature is low, the cooling rate of the strand becomes faster, but the surface is rapidly cooled and solidifies, but the central part is not sufficiently cooled and is in a molten state, so it is introduced into the density difference due to the temperature difference and / or the cutting process. A large amount of air bubbles are generated in the inside of the strand due to the drawing effect due to the take-up, and a large amount of cracks and chips occur when cutting in that state. On the other hand, if the water temperature is raised, the water approaches the boiling state, and the operability becomes very poor. As a result, it is important to practice the present invention that the cooling rate of the strand is 60 ° C./sec or less. The term "strand cooling rate" used herein means a value obtained by dividing the difference in temperature between the strands in the molten state immediately before they come into contact with water and the time when they no longer come into contact with the water, by the time in which they come into contact with water. The temperature of the strand represents the surface temperature of the strand, and the measuring method is not particularly limited, but it is preferable to measure with a non-contact type radiation thermometer that uses infrared rays.

The second point of the present invention is to control the strand temperature after being cooled with water from a molten state within a certain range. If the strand temperature after cooling is high and is close to the glass transition temperature, it becomes difficult to operate in the cutting step, and conversely, if the temperature is low, more bubbles are generated inside the strand during cooling. The strand temperature here is 10 from the glass transition temperature of the polyarylate resin.
The temperature is adjusted to -50 ° C, preferably 20-40 ° C lower. Although this temperature varies depending on the type of polyarylate resin and the like, it is selected from the range of 100 to 180 ° C., preferably 110 to 170 ° C. as an absolute value. Further, although the surface of the strand is solidified at this strand temperature, it is often not completely solidified up to the central portion, and it is possible to solidify up to the central portion by keeping this temperature for a while. When the holding time is 2 seconds or longer, preferably 4 seconds or longer, the strand can be completely solidified up to the center. If this holding time is short, the center part will not solidify, and problems such as strands wrapping around the pelletizer at the time of cutting will occur, or even if cutting can be done without problems, something like a beard will occur on the pellet, resulting in Moreover, it causes dust, which is not preferable. On the contrary, if you try to solidify to the center by cooling by applying cold air to shorten the holding time, bubbles will be generated inside the strand, and further residual strain will occur during solidification and it will be easily broken at the time of cutting It is not preferable.

In this way, the strand is cooled from the molten state to an appropriate temperature, and after a predetermined holding time has elapsed, it is cut into pellets by a pelletizer or the like in the cutting step. It is preferable to further lower the strand temperature in order to prevent problems such as the strand being wrapped around the cutter blade. That is, the strand temperature at the time of being introduced into the cutting step is higher than the glass transition temperature of the polyarylate resin by 50.
It is preferably cooled to a temperature lower by ˜70 ° C. This temperature is selected from the range of 90 to 140 ° C. as an absolute value. If the strand is cut at a temperature close to the glass transition temperature, there may be a problem in the operability in the cutting process as described above. Conversely, at a temperature considerably lower than the glass transition temperature, the strand becomes too hard and the Pellet chips and fine powder are likely to occur.

The pelletizer used in the cutting step is not limited in structure and shape as long as it is usually called a strand cutter. For example, a commercially available cutter manufactured by Osaka Seiki Kogyo Co., Ltd. or Isuzu Kakoki Co., Ltd. may be mentioned. The shape of the cutter, the number of blades, the number of rotations, the take-up speed, etc. are appropriately selected according to the extrusion capability of the extruder, the number of die nozzles, and the desired shape of pellets. For example, the take-up speed of the strand is 20-100.
m / min, and the pellet size is adjusted to 2 to 4 mm. The pellet diameter is 1.5 to 4.0 m as described above.
A range of m is preferred.

[0029]

EXAMPLES Next, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these Examples, and various modifications and alterations can be made without departing from the spirit of the present invention. It can be applied. The obtained samples were evaluated by the following methods. (1) Glass transition temperature The sample was heated from 30 ° C. to 280 ° C. with a differential scanning calorimeter, and the inflection point was taken as the glass transition temperature. (2) Temperature of Strand When the strand was not in contact with water, its surface temperature was measured with a non-contact type radiation thermometer. (3) Strand cooling rate (° C / sec) By the method of (2), the temperature immediately before the strand comes into contact with water and the temperature immediately after being separated from the water are measured, and the difference in temperature is measured when the strand comes into contact with water. Calculated by dividing by the time. (4) Ratio of Bubbles in Strand (mm / m) 1 m of the strand immediately before reaching the pelletizer through the cooling process from the extruder was sampled, and the length of the bubble portion inside the strand was added along the strand. (5) Fine powder of pellets (mg / kg) A 1 kg sample of the pellet was passed through a sieve with a mesh of 1 mm, and the mass of the powder passing through this was measured. (6) Fragment of pellets (mg / kg) A 1 kg sample of pellets was passed through a sieve with an opening of 2 mm, and what passed therethrough was further passed through a sieve with an opening of 1 mm, and the mass of what remained on the sieve was measured. (7) Appearance of molded product The pellets were dried at 120 ° C for 6 hours or more using a hot air dryer, and a mirror-finished plate was molded by an injection molding machine. Aluminum was vapor-deposited on the plate in a bell jar type vacuum device, and the appearance was visually observed.

Reference Example 1 (Preparation of polyarylate by interfacial polymerization) 100 parts by weight of 2,2-bis (4-hydroxyphenyl) propane and p-tert in a reaction vessel equipped with a stirrer.
-Butylphenol 3.4 parts by weight, sodium hydroxide 4
1.4 parts by weight and 0.6 parts by weight of trimethylbenzylammonium chloride were charged and dissolved in 1350 parts by weight of water (aqueous phase). Separately, 93 parts by weight of a terephthalic acid chloride / isophthalic acid chloride = 1/1 mixture was dissolved in 767 parts by weight of methylene chloride (organic phase). This organic phase was added to the previously prepared aqueous phase with vigorous stirring, and a polymerization reaction was carried out for 2 hours. Thereafter, 50 parts by weight of acetic acid was added to stop the reaction, the aqueous phase and the organic phase were separated, and the washing with water was repeated until the organic phase became neutral to obtain a methylene chloride solution in which 17% by mass of polyarylate was dissolved. It was Then, 100 parts by weight of warm water at 50 ° C. was added with 9 parts of a methylene chloride solution of polyarylate.
0 parts by weight was added, and the mixture was heated with stirring to maintain 50 ° C. to distill off methylene chloride to obtain a slurry of granular polyarylate resin. Further, the slurry was subjected to solid-liquid separation to obtain only a polymer component, which was dried with a hot air dryer to obtain a polyarylate resin. The molecular weight of the obtained polyarylate resin in terms of styrene by GPC was 67,000. The glass transition temperature was 185 ° C.

Example 1 A twin-screw extruder equipped with a two-stage vent section (manufactured by Toshiba Machine Co., Ltd., 50
mmφ, the same rotation direction of the screw), the polyarylate resin obtained in Reference Example 1 was continuously supplied at a rate of 50 kg / h from a supply port provided at the base thereof, and melt-kneaded to 100 mesh. 3 after passing through the screen
Four molten strands were extruded from a die set at 40 ° C and taken at a speed of 42 m / min. The strand was dipped in a water bath at 90 ° C. for 3.5 seconds, and after about 4 seconds, introduced into a pelletizer and cut into a length of about 3 mm to obtain pellets of polyarylate resin. The strand temperature before and after cooling was 342 ° C. immediately before being immersed in water and 162 ° C. immediately after leaving the water tank.
It was 1 ° C./second. The diameter of the strand is 2.2m.
In m, the rate of bubbles in the strand was 50 mm / m. When the obtained pellets were evaluated, the fine powder contained was 20 mg / kg and the pieces were 40 mg / kg, and the appearance of the molded product was good. The results are shown in Table 1.

Comparative Example 1 Pellets were obtained in the same manner as in Example 1 except that the temperature of the water tank for cooling the strand was 45 ° C. The strand temperature before and after cooling was 342 ° C. immediately before being immersed in the water tank, and 103 ° C. immediately after leaving the water tank, and the time of immersion in the water tank was 3.
5 seconds and thus the cooling rate was 68 ° C./second. The diameter of the strand was 2.3 mm, and the ratio of bubbles in the strand was 310 mm / m. The fine powder contained in the obtained pellets is 130 mg / kg, and the pieces are 370 m.
It was g / kg, and a silver streak was found in the appearance of the molded article of the pellet. The results are shown in Table 1.

Comparative Example 2 Example 1 except that the time for cooling the strand was 4 seconds
Pellets were obtained in the same manner as in. The strand temperature before and after cooling was 342 ° C immediately before it was immersed in the water tank, and 1 immediately after leaving the water tank.
23 ° C. and thus the cooling rate was 55 ° C./sec. The diameter of the strand was 2.1 mm, and the ratio of bubbles in the strand was 185 mm / m. Fine powder contained in the obtained pellets is 70 mg / kg, and fragments are 280 mg.
It was / kg. Silver streak was found in the appearance of the molded article of the pellet. The results are shown in Table 1.

Example 2 The same extruder as in Example 1 was used, and in the same manner as in Reference Example 1
The polyarylate resin obtained in 1. was extruded at a rate of 50 kg / h, and four molten strands were extruded from a die and taken at a speed of 42 m / min. While pulling the strand, while sliding on a steel plate having a smooth surface, water of 95 ° C. was continuously sprayed while the strand advanced 2.4 m. Approximately 4 seconds later, it was introduced into the pelletizer and the length was about 3
It was cut into mm to obtain pellets of polyarylate resin. The strand temperature before and after cooling is 339 ° C just before sprinkling water,
The temperature was 155 ° C. immediately after the completion of the water application, the time during which the strand was watered was 3.4 seconds, and when converted into the cooling rate, it was 54 ° C./second. The diameter of the strand is 2.1 mm, and the ratio of bubbles in the strand is 45 mm / m.
Met. When the obtained pellets were evaluated, the fine powder contained was 20 mg / kg and the fragments were 30 mg / kg, and the appearance of the molded product was good. The results are shown in Table 1.

Example 3 35 kg / h of the polyarylate resin obtained in Reference Example 1 and 15 k of a polycarbonate resin (manufactured by Teijin Chemicals Ltd., trade name Panlite L-1225W, viscosity average molecular weight 22200) are used.
Example 1 from a mass type weighing machine at a rate of g / h
Was fed to the same twin-screw extruder. Melt and knead 100
After passing through a mesh screen, extrude 4 molten strands from a die set at 300 ° C,
It was collected at a speed of 42 m / min. 75 that strand
The pellet was immersed in a water bath at 0 ° C. for 3 seconds, then, after about 4 seconds, introduced into a pelletizer and cut into a length of about 3 mm to obtain a pellet of the polyarylate resin composition. The strand temperature before and after cooling was 308 ° C immediately before immersion in water and 1 immediately after leaving the water tank.
The temperature was 41 ° C., which was 56 ° C./second when converted into the cooling rate. The diameter of the strand was 2.1 mm, and the ratio of bubbles in the strand was 70 mm / m. When the obtained pellets were evaluated, the fine powder contained was 30 mg / k.
g, the fraction was 60 mg / kg, and the appearance of the molded product was good. The results are shown in Table 1.

[0036]

[Table 1]

[0037]

EFFECTS OF THE INVENTION According to the present invention, by suppressing the generation of bubbles in the strand during pelletization, the pellet shape is made uniform and bubbles, fine powder, dusting, etc. are reduced, and pellets of polyarylate resin that are easy to handle are manufactured. be able to. Furthermore, by using the polyarylate resin pellets produced by the method of the present invention, the occurrence of silver streaks is suppressed during molding, and a molded product having a good appearance can be obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F201 AA27 AR06 AR12 AR20 BA02                       BC01 BC03 BC12 BC15 BL13                       BL25

Claims (4)

[Claims] 1. A method for producing a polyarylate resin pellet by cooling a strand of a molten polyarylate resin in a water tank and then cutting the strand, wherein the temperature is maintained at a temperature 100 to 120 ° C. lower than the glass transition temperature of the polyarylate resin. The molten strand is immersed in a water bath, and the strand is cooled at a cooling rate of 60 ° C./sec or less until the temperature becomes 10 to 50 ° C. lower than the glass transition temperature of the polyarylate resin, and the temperature is further changed to 2 seconds. A method for producing a polyarylate resin pellet, which comprises cutting the strand after holding the above. 2. A method for producing polyarylate resin pellets by spraying water on a molten polyarylate resin strand to cool it, and then cutting the strand to obtain polyarylate resin pellets, wherein water having a temperature 100 to 120 ° C. lower than the glass transition temperature of the polyarylate resin is used. Is sprayed onto the strand, the strand is cooled at a cooling rate of 60 ° C./sec or less until the temperature becomes 10 to 50 ° C. lower than the glass transition temperature of the polyarylate resin, and the temperature is maintained for 2 sec or more, and then the strand A method for producing a polyarylate resin pellet, which comprises cutting the resin. 3. The temperature of the strand is cooled to 10 to 50 ° C. lower than the glass transition temperature of the polyarylate resin, the temperature is maintained for 2 seconds or more, and then the temperature of the strand is lower than the glass transition temperature of the polyarylate resin. 50-
The method for producing polyarylate resin pellets according to claim 1 or 2, which comprises cooling again to a temperature lower by 70 ° C and then cutting. 4. The strand diameter is 1.5 to 4.0 mm.
4. The method for producing polyarylate resin pellets according to claim 1, wherein the polyarylate resin pellets are in the range.