JPH0453824A - Method of solid state polymerization of aromatic polycarbonate - Google Patents

Abstract

PURPOSE:To obtain a high-quality arom. polycarbonate without allowing bridging to occur by intermittently increasing the amt. of flow of an inert gas in the solid state polymn. of a crystalline polycarbonate prepolymer by the fixed or moving bed method. CONSTITUTION:In the solid state polymn. of a crystalline polycarbonate prepolymer by the fixed or moving bed method under the flow of an inert gas, the amt. of the flowing gas is intermittently increased so as to bring about a temporary fluidized bed state. Thus a high-quality arom. polycarbonate is prepd. without allowing bridging to occur by the fixed or moving bed method which requires less amt. of the flowing inert gas than the fluidized bed method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for solid-phase polymerization of aromatic polycarbonate, which is an engineering plastic.

[Prior art and problems to be solved by the invention] Aromatic polycarbonates have been industrialized by an interfacial polycondensation method of 2,2'-bis(4hydroxyphenyl)propane (hereinafter referred to as bisphenol A) and phosgene. . This method has disadvantages in that toxic phosgene must be used, by-products such as hydrogen chloride and sodium chloride are corrosive, and if they remain in the polymer, they will adversely affect physical properties. Another drawback is that a large amount of methylene chloride is used as a solvent, making it difficult to separate the polymer, and residual methylene chloride also adversely affects physical properties.

A transesterification method in which bisphenol A and diphenyl carbonate are melt-polymerized is also known, but because the polymerization is carried out using a catalyst at high temperatures, it has the drawbacks of poor color, easy branching, and difficulty in producing high molecular weight polymers. .

The present inventors have disclosed in Japanese Patent Application No. 1-171084 that a high-quality aromatic polycarbonate containing no chlorine compounds can be obtained by solid-phase polymerizing a crystalline polycarbonate prepolymer in an inert gas stream. I filed an application. The patent describes the types of solid phase polymerizers as tumbler type, kiln type, paddle dryer type, screw conveyor type,
The vibrating type, fluidized bed type, fixed bed type, moving bed type, etc. are described.

Among these methods, fixed bed type and moving bed type have advantages such as simple equipment and low flow rate of inert gas used, but on the other hand, polymers stick together in the polymerization vessel and prudence occurs. There was a problem that it was easy to occur.

[Means to solve the problem]

An object of the present invention is to overcome these handling problems and provide an industrially advantageous method for homopolymerizing aromatic polycarbonate.

As a result of intensive research on the production method of aromatic polycarbonate by solid-phase polymerization, the present inventors solid-phase polymerized crystalline polycarbonate prepolymers under an inert gas flow in a fixed bed system or a moving bed system to achieve a high degree of polymerization. In manufacturing aromatic polycarbonate, the inventors discovered that the above problem could be solved by intermittently increasing the flow rate of inert gas and temporarily creating a fluidized bed state.Based on this knowledge, the present invention was completed. I let it happen.

That is, in the present invention, a crystalline polycarbonate prepolymer is solid-phase polymerized in a fixed bed system or a moving bed system under an inert gas flow. This is a solid phase polymerization method for aromatic polycarbonate, which is characterized in that in producing aromatic polycarbonate having a ti11i degree, the flow rate of an inert gas is increased intermittently to temporarily create a fluidized bed state.

In the present invention, the fixed bed method or the moving bed method is carried out under the condition that the packed crystalline polycarbonate prepolymer and the aromatic polycarbonate in the middle of polymerization do not flow due to an inert gas. The flow of the inert gas varies depending on the particle size of the crystalline polycarbonate prepolymer and is not particularly limited, but the superficial velocity is usually 0.001 to 1.0 m/s.
It is ec. In the present invention, while the solid-state combination is progressing using a fixed bed method or a moving bed method, the inert gas flow rate is increased intermittently to temporarily create a fluidized bed state.

There is no particular restriction on the time to maintain the fluidized bed state, but it is usually about 0.5 seconds to 10 seconds. Further, there is no particular restriction on the frequency of bringing the fluidized bed into a state, but it is usually preferable to bring the fluidized bed into an interval of 0.5 to 30 minutes.

In addition, the inert gas flow i1 when creating a fluidized bed state in the present invention! The amount is the amount necessary to temporarily bring the crystalline polycarbonate prepolymer and the aromatic polycarbonate during polymerization into a fluidized bed state.

It depends on the particle size of the crystalline polycarbonate prepolymer, and there is no particular limit, but the superficial velocity is usually 0.1 to 5.
m/sec.

The crystalline polycarbonate prepolymer used in the present invention is represented by the formula;

Such aromatic residues include, for example, phenylene (various types), naphthylene (various types), biphenylene (various types), pyridazine (each a), and the following - ship stock; Examples include aromatic groups.

Here, Ar" and Ar" are divalent aromatic groups which may be the same or different, and include, for example, phenylene [11], naphthylene (various types), biphenylene (
Represents groups such as (various), pyridazine (various), etc. Z is a simple bond or -〇--CO-S--3O2--CO2-
-CON(R') represents a divalent group. (Here, R1, R
2, R3 and R' may be the same or different,
It represents a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a cycloalkyl group, and k represents an integer of 3 to 11. ) Furthermore, in such a divalent aromatic group (i.e., Ar', or Ar2, Ar5), one or more hydrogen atoms are
Other substituents that do not adversely affect the reaction, such as halogen atoms, lower alkyl groups, lower alkoxy groups, phenyl groups, phenoxy groups, vinyl groups, cyano groups, ester groups,
It may be substituted with amide 4, nitro group, etc.

Such an aromatic group includes, for example, a substituted or unsubstituted phenylene group represented by: a substituted or unsubstituted biphenylene group represented by: (R5 and R
6 is a hydrogen atom, a halogen atom, a lower alkyl group having 1 to 4 carbon atoms, a lower alkoxy group having 1 to 4 carbon atoms, a cycloalkyl group, or a phenyl group, and these may be the same or different from each other. m and n
is an integer from 1 to 4, and when m is 2 or more, R5 may be different from each other, and when n is 2 or more, R6 may be different from each other). Examples include substituted or unsubstituted divalent aromatic groups.

Among these structures, Ar' is CB.

OCCH3 etc.

CH.

CH2 Examples are 10, -CH,, -C-CI,.

CH3 The polycarbonate includes those having a branched structure using a compound having a trifunctional or higher functional group.

Furthermore, it is also possible to include an ester bond in the main chain structure within a range that does not impair the effects of the present invention.

Further, there is no particular restriction on the degree of crystallinity of the crystalline polycarbonate prepolymer used in the present invention, but the degree of crystallinity is usually in the range of 5 to 55% (according to X-ray diffraction method).

The number average molecular weight of the crystalline polycarbonate prepolymer used in the present invention is 1,500 or more, preferably 2.0.
00 to 20,000.

Furthermore, the terminal groups of the crystalline polycarbonate prepolymer consist of hydroxyl groups and aryl carbonate groups. There is no particular restriction on the ratio of hydroxyl group to aryl carbonate group, but from the viewpoint of polymerization rate it is 10:90-90.
:10, particularly preferably in the range of 20:80 to 80:20.

There are no particular limitations on the shape of the crystalline polycarbonate prepolymer used in the present invention. It may be in the form of irregular shapes or granules, but it may also be in the form of pellets, tablets, etc. molded by known seeding methods such as extrusion granulation or compression molding.

The inert gas used in the present invention includes nitrogen ions,
Examples include argon and CO2. Nitrogen is particularly preferred from the viewpoint of easy availability.

The production method of the present invention is carried out by solid phase polymerization at a temperature above the glass transition temperature and below the melting point of the crystalline polycarbonate prepolymer, and is in the range of 150°C to 260°C.

The pressure for solid phase polymerization is not particularly limited, and it can be carried out at reduced pressure, normal pressure, or increased pressure.

The number average molecular weight of the aromatic polycarbofoot obtained by solid phase polymerization is usually 6,000 to 200,000.

Note that solid-phase polymerization is possible in the presence or absence of a catalyst, and non-catalytic polymerization is preferable because the color, heat resistance, and hot water resistance of the resulting polymer are superior to P stages. As the polymerization catalyst, various known transesterification catalysts used for polycarbonate or polyester can be used. Examples include alkali metal salts of bisphenol A, tin, and button compounds.

The method for obtaining the crystalline polycarbonate preponomer used in the present invention is usually to first synthesize a non-grade polycarbonate prepolymer and then to crystallize the non-grade polycarbonate prepolymer.

There are no particular limitations on the method of synthesizing the non-quality prepolymer, and it can be synthesized by the various methods described below.

That is, a method of synthesizing by melt polymerization of biphenol such as bisphenol A and diaryl carbonate by transesterification method, and interfacial polycondensation of biphenol and phosgene in the presence of an aromatic monohydroxy compound such as phenol or tert-butylphenol as a terminal stopper. A method in which a condensate of biphenol and diaryl carbonate at a molar ratio of 1:2 is synthesized in advance and this is melt-polymerized with biphenol.A method in which excess phosgene and phenol are reacted with biphenol in interfacial polycondensation. Examples include a method in which biphenol is newly added to a phenyl carbonate-terminated polycarbonate oligomer obtained by melt polymerization.

Although there are no particular limitations on the method for crystallizing the non-quality polycarbonate prepolymer, solvent treatment methods and heating crystallization methods are usually preferably used.

The former solvent treatment method is a method in which a prepolymer is crystallized using an appropriate solvent. Specifically, an amorphous prepolymer is dissolved in a solvent, and then a crystalline prepolymer is precipitated from this solution. The prepolymer is kept in a liquid state for a period of time necessary for the solvent to penetrate into the non-quality prepolymer and crystallize the amorphous prepolymer by using a solvent with low dissolving power for the prepolymer. A method of contacting with a solvent or solvent vapor is preferably used.

Solvents that can be used for solvent treatment of such amorphous prepolymers include, for example, chloromethane, methylene chloride, chloroform, carbon tetrachloride, chloroethane, dichloroethane (various), trichloroethane (each W), l-
Aliphatic halogenated hydrocarbons such as dichloroethylene and tetrachloroethane (various); aromatic halogenated hydrocarbons such as chlorobenzene and dichlorobenzene; ethers such as tetrahydrofuran and dioxane; esters such as methyl acetate and ethyl acetate Ketones such as acetone and methyl ethyl ketone; Aromatic hydrocarbons such as benzene, toluene and xylene. Halogen-free solvents are particularly preferred in order to obtain high quality polymers. One type of these solvents may be used, or two types may be used.
A mixture of more than one species may be used.

On the other hand, the heating crystallization method is a method in which the prepolymer is crystallized by heating at a temperature that is above the glass transition temperature of the target aromatic polycarbonate and below the temperature at which the prepolymer begins to melt. be. Since this method can be crystallized simply by holding the prepolymer under heat, it can be carried out in a very convenient manner on an industrial scale.

〔Example〕

EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

Note that the molecular weight is a number average molecular weight measured by gel vermusion chromatography (GPC).

The end groups in the prepolymer were analyzed by high performance liquid chromatography or NMR.

Crystallinity was determined by powder X-ray diffraction according to patent application No. 63-24078.
It was determined by the method described in No. 5.

Example 1 Crystals with a number average molecular weight of 4,000, 36% terminal hydroxyl groups, 64% terminal phenyl carbonate groups, and 24% crystallinity were obtained by solvent crystallization using acetone using bisphenol A and diphenyl carbonate as raw materials. A polycarbonate prepolymer with a diameter of 31 mm was processed using a rotary granulator (Disc pelleter F-5 manufactured by Fuji Baudal).
Using pellets molded to 1t111 and approximately 5cm in length,
Solid phase polymerization was carried out in an SO3304 gas flow reactor with an inner diameter of 200 m+.

The polymerization conditions were as follows: Nitrogen was constantly supplied at 13 Nm/Hr to 10 kg of the charged crystalline polycarbonate prepolymer, and nitrogen was pulsed at 8ONrrr/Hr for 3 seconds once every 20 minutes at 210°. It was done in C.

With a polymerization time of 10 hours, a polymer with number average molecular weight [13,300] was obtained. During the polymerization, the pellets were normally in a stationary state, but when nitrogen was pulsed at 8ON/Hr, they were fluid, and after 10 hours of polymerization, the pellets (
There were no pecks at all.

Example 2 The same pellets as in Example 1 were used, and the polymerization temperature was 220°C.
Solid phase polymerization was carried out in exactly the same manner as in Example 1, except that the frequency of intermittently changing the fluidized bed state was once every 10 minutes. After a polymerization time of 5 hours, a polymer having a number average molecular weight of 12,500 was obtained, and no sticking of the pellets to each other was observed.

Comparative Example 1 Surface phase polymerization was carried out in the same manner as in Example 1, except that nitrogen was not supplied in pulses once every 20 minutes.

After 10 hours of polymerization, a polymer with a number average molecular weight of 13.100 was obtained, but the pellets stuck together, causing a prying phenomenon in the polymerization vessel.

Example 3 The same crystalline polycarbonate prepolymer as in Example 1 was molded into pellets with a diameter of 2 m and a length of about 3 mm using an extrusion granulator (manufactured by Fuji Baudal Mai, EXKF-1 type pelletizer). Solid phase polymerization was carried out in the same manner as in 1. However, the nitrogen flow in pulses is 6ONr once every 30 minutes.
rf/Hr for 4 seconds each time. Polymerization time 10
A polymer with a number average molecular weight of 13.300 was obtained in hours. During the polymerization, when nitrogen was pulsed at 6ON/hr, the pellets were fluid, and after 10 hours of polymerization, the pellets did not stick together at all.

Example 4 Synthesized by interfacial polycondensation of bisphenol A and phosgene in the presence of phenol, followed by solvent crystallization using acetone. Number average molecular weight 3,500, terminal hydroxyl group 40%, terminal phenyl carbonate group. A crystalline polycarbonate prepolymer having a crystallinity of 60% and a crystallinity of 23% was pelletized in the same manner as in Example 1, and solid phase polymerization was performed. However, the fluidization state was intermittently carried out once every 10 minutes until 2 hours after the start of polymerization, and once every 30 minutes from 2 hours to 10 hours. After 10 hours, the number average molecular weight was 12.900, and no adhesion between berenes was observed.

Example 5 Bisphenol A with a number average molecule i3,800 obtained by solvent crystallization using acetone using bisphenol A, bisphenol S and diphenyl carbonate as raw materials
The ratio of Unisito and Bisphenol S Unisito is 9515
(molar ratio), 50% terminal hydroxyl groups, 50% terminal phenyl carbonate groups, and 22% crystallinity crystalline polycarbo Z, -Dobrebotsmer was formed into pellets in the same manner as in Example 1, and solid phase polymerization was performed. Ta. After 10 hours, the number average molecular weight of the polymer was 11,900, and no sticking of the pellets to each other was observed.

〔Effect of the invention〕

The present invention is an industrially advantageous method that makes it possible to produce high-quality aromatic polycarbonate without causing bridging using a fixed bed method or a moving bed method that uses a lower inert gas flow rate than a fluidized bed method. This is a solid phase polymerization method.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] When producing aromatic polycarbonate with a high degree of polymerization by solid-phase polymerization of crystalline polycarbonate prepolymer in a fixed bed method or moving bed method under inert gas flow, the amount of inert gas flow is increased intermittently and temporary polymerization is performed. A method for solid-phase polymerization of aromatic polycarbonate, which is characterized in that it is in a fluidized bed state.