JP2002187193A - Method for producing polycarbonate resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polycarbonate resin molding containing only a trace amount of a chlorine compound from a methylene chloride solution of the polycarbonate resin without using a special extruder or without replacing the solvent with another one. SOLUTION: In the method for producing the polycarbonate molding continuously from the methylene chloride solution of the polycarbonate resin by using a twin-screw extruder with multistage (at least three) vents, the solution is heated in the extruder to the melting temperature of the resin while the solvent is volatilized to obtain the molten polycarbonate resin the chlorine content of which is 2,000 ppm or below. Next, the molten resin, after water is added, is extruded while being degasified by the vents downstream from a water inlet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a molded article of a polycarbonate resin. More specifically, the present invention relates to a method for producing a polycarbonate resin molded product in which a polycarbonate resin molded product having an extremely small chlorine compound content is continuously produced from a methylene chloride solution of a polycarbonate resin by a simple method.

[0002]

2. Description of the Related Art Polycarbonate resins are excellent in transparency, heat resistance, impact resistance, etc., and are therefore melt-molded by injection molding, compression molding, extrusion molding, rotational molding, and the like. It is used for applications. Such a polycarbonate resin, particularly a polycarbonate resin produced by a so-called interfacial polymerization method in which a dihydric phenol and phosgene are reacted in the presence of methylene chloride, is obtained by using a chlorine compound such as methylene chloride or a compound having a chloroformate group as a terminal residual group. These chlorine compounds are contained, albeit slightly, and decompose during melt molding to generate acidic substances, which cause corrosion of molds and corrosion of recording films of optical disks, magnetic disks and the like. In particular, in recent years, the problem of mold corrosion has been largely addressed by shortening the molding cycle. Also, recording media such as optical disks and magnetic disks have been shifting to higher densities, and corrosion of the recording film is a major problem.

In general, a methylene chloride solution of a polycarbonate resin produced by interfacial polymerization is used in a form capable of being processed by removing the methylene chloride solution by any method, for example, in the form of powder or pellets.

Polycarbonate resin A method for producing a solid polycarbonate resin from a methylene chloride solution is as follows.
Japanese Patent Publication No. 38-24724 discloses that in a state where the solution temperature is heated to a temperature at which the polycarbonate resin can flow under pressure, most of the solvent is removed, and then a trace amount of the solvent is removed under reduced pressure. It is described. To carry out this method, a special extruder was required, and further, there was a drawback that the residual solvent in the obtained polycarbonate was large.

Japanese Patent Publication No. 48-22840 discloses a method for producing a polycarbonate resin solid using a chlorinated aromatic hydrocarbon having a high boiling point. However, methylene chloride used in a polycarbonate resin polymerization step is used. And a step of substituting the above-mentioned chlorinated aromatic hydrocarbon having a high boiling point. Also in this method, the chlorinated aromatic hydrocarbon has a high boiling point, and thus has a disadvantage that the residual amount in the obtained polycarbonate resin is large.

[0006]

An object of the present invention is to use a special extruder from a methylene chloride solution of a polycarbonate resin obtained as a reaction product when a polycarbonate resin is produced by an interfacial polymerization method. Another object of the present invention is to provide a method for producing a molded article of a polycarbonate resin having an extremely small chlorine compound content without requiring a solvent replacement step with another solvent. Here, the term "molded article" refers to an extruded article in general, and includes a molded article for a molding material such as a pellet.

The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have a multi-stage vent having three or more vents.
Using a screw extruder, the polycarbonate resin methylene chloride solution was heated to a temperature at which the polycarbonate resin melted to obtain a molten polycarbonate resin having a chlorine atom content of 2000 ppm or less. By injecting and adding water immediately before venting and degassing at one or more locations by venting, it is possible to continuously produce polycarbonate resin molded products with low chlorine compound content from polycarbonate resin methylene chloride solution. Heading, the present invention has been reached.

[0008]

That is, according to the present invention, a polycarbonate resin molded article is continuously produced from a methylene chloride solution of a polycarbonate resin using a twin screw extruder equipped with a multistage vent having three or more vents. In the method, a methylene chloride solution of the polycarbonate resin is heated to the melting temperature of the polycarbonate resin in the extruder while evaporating the methylene chloride to obtain a molten polycarbonate resin having a chlorine atom content of 2000 ppm or less, and then A method is provided for producing a polycarbonate resin molded product in which water is added to the molten polycarbonate resin from before the at least one vent and melt-extruded while deaerated by a vent after the water inlet.

The methylene chloride solution of the polycarbonate resin used in the present invention is usually obtained by a so-called interfacial polymerization method in which a dihydric phenol and phosgene are reacted in the presence of methylene chloride, but the polycarbonate obtained by using another solvent is used. A solution in which a resin or a polycarbonate resin produced by a melting method or the like is dissolved in methylene chloride may be used. Basic means of the production method using the interfacial polymerization method will be briefly described.

In the interfacial polymerization method for producing a polycarbonate resin using a dihydric phenol and phosgene, the reaction is usually carried out in the presence of an acid binder and an organic solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide or an amine compound such as pyridine is used. As the organic solvent, for example, a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used. In order to promote the reaction, a catalyst such as a tertiary amine or a quaternary ammonium salt can be used. As the molecular weight regulator, it is desirable to use a terminal terminator such as an alkyl-substituted phenol such as phenol or p-tert-butylphenol. The reaction temperature is usually from 0 to 40.
C., the reaction time is preferably several minutes to 5 hours, and the pH during the reaction is preferably maintained at 10 or more.

The dihydric phenol used herein includes hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane,
1,1-bis (4-hydroxyphenyl) ethane, 2,
2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A), 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane (commonly known as bisphenol Z) , 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (3-isopropyl-
4-hydroxyphenylpropane, 2,2-bis (4-
Hydroxyphenyl) butane, 2,2-bis (3,5-
Dimethyl-4-hydroxyphenyl) propane, 2,2
-Bis (3,5-dibromo-4-hydroxyphenyl)
Propane, 4,4'-dihydroxydiphenyl sulphoxide, 4,4'-dihydroxydiphenyl sulphide,
3,3'-dimethyl-4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl oxide, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (3-methyl-4- Hydroxyphenyl) fluorene, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 4,
4 ′-(m-phenylenediisopropylidene) diphenol, 4,4 ′-(p-phenylenediisopropylidene) diphenol, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane and the like No. Polycarbonate resins obtained from these dihydric phenols may be used alone or in combination of two or more. However, the fact that the obtained polycarbonate resin is soluble in methylene chloride is considered to be soluble in methylene chloride. This is an essential condition in the invention. Further, as long as the compound is soluble in methylene chloride, a small amount of a compound having three or more functional groups may be used as a branching agent, or a small amount of an aliphatic bifunctional compound may be copolymerized.

In the present invention, as the methylene chloride solution of the polycarbonate resin, a polycarbonate resin solution obtained by purifying the methylene chloride solution of the polycarbonate resin obtained by the above-mentioned production method by washing with water or the like is preferably used.

In the present invention, the polycarbonate resin solution may be supplied as it is to a twin-screw extruder, or methylene chloride may be volatilized to some extent, and a concentrated solution or a paste-like material may be twin-screw extruded. Machine. Preferably, a solution state is supplied to the extruder.

A transportation line (pipe) for connecting the polycarbonate resin solution and the twin-screw extruder is provided, and the transportation line is heated to concentrate the polycarbonate resin solution under the condition that the transportation line is not blocked. A method of continuously supplying the obtained resin solution or paste to a twin-screw extruder is also employed. The degree of concentration is appropriately adjusted so that a polycarbonate resin having a low chlorine atom content can be stably obtained. Hereinafter, the polycarbonate resin solution or paste supplied to the twin-screw extruder may be referred to as “polycarbonate supply”.

The polycarbonate feed supplied to the twin-screw extruder is preferably substantially free of water, and desirably has a water content not higher than the saturation solubility. If water having a saturation solubility or higher exists, hydrochloric acid may be generated due to contact between water and methylene chloride at a high temperature.

The concentration of the polycarbonate resin solution supplied to the twin-screw extruder is appropriately selected depending on the molecular weight of the polycarbonate resin, and is preferably 5% by weight or more. When the solution concentration is 5% by weight or more, it becomes easy to efficiently obtain a target polycarbonate resin having a low chlorine compound content. The solution concentration is preferably a high concentration in consideration of productivity, but a polycarbonate resin having crystallinity, such as a polycarbonate resin using bisphenol A, has a limit to the solubility of the polycarbonate resin in methylene chloride. Is preferably supplied to a twin-screw extruder. Polycarbonate resin having high amorphousness, such as a polycarbonate resin using bisphenol Z, can have a high concentration. However, considering the supply to the twin-screw extruder, the viscosity of the polycarbonate resin methylene chloride solution or paste supplied to the twin-screw extruder is preferably 5,000 poise or less. If the viscosity of the polycarbonate supply is too high, supply to the twin-screw extruder becomes difficult, and problems such as blockage of the transport line may occur.

The twin-screw extruder with a multi-stage vent used in the present invention requires three or more vents. Preferably 3
To 6 locations, more preferably 4 to 6 locations.

In the twin-screw extruder, (1) a zone for concentrating to reduce the proportion of the solvent in the polycarbonate feed (pre-concentration zone); and (2) a chlorine atom content of the molten polycarbonate resin is reduced to 2000 ppm or less. Zone for further concentration (post-concentration zone) and (3) a zone for injecting and adding water, degassing from the vent portion, and extruding the molten polycarbonate resin (water addition zone).
And at least one vent is required for each zone.

The polycarbonate feed is supplied to a twin-screw extruder at room temperature or in a heated state. In the pre-concentration zone,
The polycarbonate feed supplied to the twin-screw extruder proceeds toward the extruder outlet while being sequentially concentrated in the twin-screw extruder at a temperature equal to or higher than the boiling point of methylene chloride. It is preferable that the concentration temperature is gradually increased in the direction in which the resin travels.
The temperature is set according to the glass transition temperature of the polycarbonate resin and the concentration or viscosity of the polycarbonate feed.
It is preferable to optimize as appropriate. The temperature may be raised to a temperature at which the polycarbonate is melted. The methylene chloride volatilized up to the seal portion immediately before the post-concentration zone is discharged to the outside of the extruder through a vent installed in the pre-concentration zone under normal pressure or reduced pressure, preferably under normal pressure. When the pressure is reduced, it is sufficient to promote the discharge of methylene chloride. If the degree of pressure reduction is high, venting may occur due to foaming, which is not appropriate. The position of the methylene chloride discharge vent installed in the pre-concentration zone may be either before or after the supply port of the polycarbonate supply, but is preferably between the supply port and the screw root in order to prevent vent up.

In this pre-concentration zone, most of the methylene chloride in the polycarbonate feed is volatilized and discharged out of the extruder through a vent. It is preferable that a seal portion is provided between the pre-concentration zone and the post-concentration zone because methylene chloride volatilized in the pre-concentration zone is easily discharged out of the extruder. The polycarbonate resin concentrated in the pre-concentration zone then moves to the post-concentration zone.

The post-concentration zone is a zone where the polycarbonate resin is melted and kneaded, and the chlorine atom content in the molten polycarbonate resin can be reduced to 2000 ppm or less by reducing the pressure of the vent to a high degree. The set temperature of the post-concentration zone is not lower than the melting temperature of the polycarbonate resin to be used and should not exceed the decomposition temperature.

Further, at least one vent portion is required in the post-concentration zone, and it is preferable to increase the degree of pressure reduction to the upper limit at which vent-up can be suppressed. The degree of reduced pressure is preferably from 1.3 × 10 ^{2 to} 6.6 × 10 ⁴ Pa, more preferably from 1.3 × 10 ^{3 to} 4.0 × 10 ⁴ Pa. It is preferable that the depressurized vent portions are individually sealed, and the methylene chloride remaining in the polycarbonate resin is efficiently removed. The molten polycarbonate resin obtained in the post-concentration zone has a chlorine atom content of 2000 p.
pm or less, preferably 1000 ppm or less, more preferably 500 ppm or less. If the chlorine atom content in the polycarbonate resin remains more than 2000 ppm, then, when water is added and added, hydrochloric acid may be generated due to the contact between water and methylene chloride, the main component of the chlorine atom-containing compound. And the generated hydrochloric acid is
Corrosion of the twin-screw extruder may occur, and corrosive substances are mixed in the polycarbonate resin as foreign substances, which is not preferable. Further, it becomes difficult to obtain a target polycarbonate resin having a low chlorine atom content. This chlorine atom content 20
00 ppm or less of the molten polycarbonate resin then moves to the water addition zone.

In the water addition zone, an operation of injecting and adding water to the molten polycarbonate resin and performing degassing from a vent located downstream of the water injection port is performed.

The addition of water has the effect of reducing the chlorine atom content of the polycarbonate resin obtained. Injection and addition of water is necessary at least at one or more places. Injection and addition of water at two or more places is required to achieve the target level of the chlorine atom content in the molten polycarbonate resin and the chlorine atom content in the obtained polycarbonate resin molded article. In addition, it may be appropriately implemented. If the amount of water added is too small, the effect of water injection does not appear, and the chlorine atom content in the polycarbonate resin molded product does not decrease. On the other hand, if the amount is too large, deaeration in the vent portion where the pressure is reduced is insufficient, and adverse effects such as hydrolysis will be exerted on the polycarbonate resin. Preferably, the amount is 0.2 to 4 parts by weight per 100 parts by weight of the polycarbonate resin.

The degree of vacuum at each vent in the water addition zone is preferably 6.7 × 10 ³ Pa or less,
It is more preferably 4.0 × 10 ³ Pa or less. When the degree of vacuum is in such a range, the water added and injected is sufficiently removed at the vent portion, and the polycarbonate resin is preferably not adversely affected by hydrolysis or the like.

The cylinder temperature in the water addition zone may be any temperature at which the polycarbonate resin used melts.
The temperature is preferably about the same as that of the post-concentration zone.

The polycarbonate resin molded product obtained by the method of the present invention preferably has a chlorine atom content of 10 p.
pm or less, more preferably 7 ppm or less, particularly preferably 5 ppm or less. The polycarbonate resin molded product having an extremely small chlorine atom content can be suitably used as a substrate of an information recording medium such as an optical disk or a magnetic disk.

The additives to be added to the polycarbonate resin molded article as desired may be added in advance to a methylene chloride solution of the polycarbonate resin, and then the polycarbonate resin molded article of the present invention may be produced. In addition, when using an additive that easily sublimates or evaporates, if the additive is added at a position closer to the extruder nozzle than the vent immediately after water injection and addition closest to the extruder nozzle, escape to the outside of the system can be significantly prevented. It is preferred. In this case, venting is not necessary after the additives have been added. The locations where additives are added are 1-3
The location is appropriate. The kind of the additive may be one kind or plural kinds. In the case of plural kinds, they may be added separately or mixed and added. The solid additive may be forcibly fed into the cylinder using a side feeder or the like, or may be added from the opening of the cylinder. Alternatively, the mixture may be heated and melted, and forcibly fed into the cylinder by an injection pump or the like. The liquid additive may be forcibly fed into the cylinder by an injection pump or the like,
It may be added from the cylinder opening.

[0029]

The present invention will be described in detail below with reference to examples. Parts in Examples are parts by weight, and% means% by weight unless otherwise specified. The evaluation was based on the following method.

(1) Specific viscosity (η _sp ): methylene chloride 10
0.7 g of polycarbonate resin dissolved in 0 ml
Measured in ° C.

(2) Chlorine atom content: When the chlorine atom content is 100 ppm or more, using a fluorescent X-ray analyzer and a calibration curve of chlorine atom content prepared in advance,
The chlorine atom content of the sample was determined. When the concentration is less than 100 ppm, the sample is completely burned, and the generated hydrogen chloride (HC
1) was subjected to potential titration with silver ions (Ag ⁺ ), and the chlorine atom content was determined from the quantity of electricity required for the potential titration.

(3) Water injection addition amount: Water injection addition amount based on the polycarbonate resin equivalent discharge amount per unit time calculated from the concentration and supply amount of the polycarbonate resin methylene chloride solution supplied to the twin-screw extruder. It was determined. The amount of water addition in Table 1 is based on 100 parts by weight of the polycarbonate resin.

(4) Chlorine atom content before water injection addition: Except that all vents after the water injection addition position were closed, the chlorine atom content of the pellets obtained by extrusion under the same conditions was determined by water injection. The chlorine atom content before the addition was taken.

[Examples 1 to 5 and Comparative Examples 1 and 2] A twin screw extruder having a screw diameter of 46φ and having four vents as shown in FIG. 1 (C0 to C12 in the figure each represent a barrel) [ HYPERKTX-46, manufactured by Kobe Steel, Ltd.], the polycarbonate resin methylene chloride solution shown in Table 1 was supplied, and extruded in a strand shape under the extrusion conditions shown in Table 1.
Cut to produce pellets. Table 1 shows the evaluation results.

The symbols of the raw materials in Table 1 are as follows.

Raw Material Resin A: A polycarbonate resin having a specific viscosity of 0.285 obtained by reacting bisphenol A and phosgene in a methylene chloride solution by an interfacial polymerization method is used in a solution (based on the total amount of resin and methylene chloride) of 15%. Methylene chloride solution containing polycarbonate resin by weight.

Raw material resin B: 50 mol% of 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and 50 mol% of 4,4 ′-(m-phenylenediisopropylidene) diphenol A polycarbonate resin methylene chloride solution containing 40% by weight (based on the total amount of resin and methylene chloride) of a polycarbonate resin having a specific viscosity of 0.275 obtained by reacting phosgene in a methylene chloride solution by an interfacial polymerization method.

[0038]

[Table 1]

[0039]

According to the present invention, the polycarbonate resin methylene chloride solution is continuously concentrated without a special extruder or a replacement step with another solvent to obtain a polycarbonate resin molded product having an extremely small chlorine compound content. It can be manufactured, and the industrial effect it produces is exceptional.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a twin-screw extruder used in the present invention.

[Explanation of symbols]

 1. Vent (1) 2. Supply port 3. 3. Vent (2) 4. Water addition port (1) Vent (3) 6. 6. Water addition port (2) Vent (4)

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Claims (4)

[Claims] 1. A method for continuously producing a polycarbonate resin molded product from a methylene chloride solution of a polycarbonate resin using a twin screw extruder with a multi-stage vent having three or more vents. While evaporating methylene chloride, the extruder was heated to the melting temperature of the polycarbonate resin in the extruder to obtain a molten polycarbonate resin having a chlorine atom content of 2000 ppm or less. And extruding while degassing at a vent downstream of the injection port. 2. The method for producing a polycarbonate resin molded product according to claim 1, wherein the chlorine atom content of the molten polycarbonate resin before water is added and added is 1,000 ppm or less. 3. The method for producing a polycarbonate resin molded product according to claim 1, wherein the water is injected a plurality of times in a portion where the polycarbonate resin is in a molten state. 4. The method for producing a polycarbonate resin molded article according to claim 3, wherein the amount of water injected and added at each water injection addition point is 0.2 to 4 parts by weight per 100 parts by weight of the molten polycarbonate resin.