JPH0359028A - Production of polycarbonate by solid-state polymerization - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

(Prior Art) Polycarbonate has been industrialized by an interfacial polycondensation method of 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A) and phosgene.

This method has the disadvantage that, in addition to the necessity of using toxic phosgene, hydrogen chloride and sodium chloride produced as by-products are corrosive, and if they remain in the polymer, they adversely affect the physical properties. Another disadvantage is that a large amount of methylene chloride is used as a solvent, and
Methylene chloride is difficult to separate from the polymer, and methylene chloride remaining in the polymer has an adverse effect on the physical properties of the polymer.

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 products with high molecular weight. are doing.

The present applicant previously disclosed in JP-A-1-158033 a technique for producing polycarbonate free from the above-mentioned problems by solid-phase polymerization of a crystalline polycarbonate prepolymer.

The method described in the above-mentioned publication is to carry out solid phase polymerization. A method for removing aromatic monohydroxy compounds by entraining them with these gases is disclosed.

When attempting to implement the above method industrially, disposing of inert gas or lower hydrocarbon gas in one bath results in a large loss in terms of cost. Therefore, it is preferable that these gases be recovered and reused.

However, depending on the recovery method, diaryl carbonates and aromatic monohydroxy compounds may remain in these inert gases and lower hydrocarbon gases. A method for solid-phase polymerization of polycarbonate by feeding a gas containing diaryl carbonate or an aromatic monohydroxy compound has not been previously known.

(Problems to be Solved by the Invention) The present invention overcomes various drawbacks of the conventional phosgene method and melting method, and provides a solid phase polymerization method for producing high-quality polycarbonate that does not contain chlorine compounds. The present invention aims to provide an industrially useful method using an inert gas containing an aromatic monohydroxy compound.

(Means for Solving the Problems) As a result of intensive studies on solid-phase polymerization of polycarbonate using an inert gas containing an aromatic monohydroxy compound, the present inventors found that by selecting specific conditions, It was discovered that the solid phase polymerization rate was increased and a high molecular weight polycarbonate could be obtained, and based on this knowledge, the present invention was completed.

That is, the present invention has; General formula (I): ]I represents the number of repetitions) When a crystalline polycarbonate prepolymer having a number average molecular weight of 1,500 or more is solid-phase polymerized in a temperature range of 150 to 260°C under an inert gas flow, The present invention relates to a method for solid-phase polymerization of polycarbonate, characterized in that the partial pressure of HOXX'' in an active gas is in the range of 0.001 to 5 msHg.

A further preferred embodiment of the present invention is the solid phase polymerization method of polycarbonate described above, in which an inert gas recovered from solid phase polymerization is used as the inert gas to be supplied.

The present invention will be explained in detail below.

The crystalline polycarbonate prepolymer used in the present invention is represented by general formula (1).

1 X (-OCOA r÷-, Y ・ ・-(1)
Here, R represents hydrogen or an alkyl group, Ar represents an aromatic residue, n represents the repeating number, )CH.

As a specific example of R, -H.

-CH,, CCHt CH.

Hs CH.

As a specific example of Ar, C.F.

etc.

In the crystalline polycarbonate prepolymer, Ar may be used alone or in combination of two or more types, but it is usually preferable that the diarylalkane residue is 50m02% or more in Ar, and more preferably 80m0j! % or more is particularly preferred.

The number average molecular weight of the crystalline polycarbonate prepolymer used in the present invention is 1.500 or more. 1.500
In the following, the solid phase heavy metal time becomes too long, and fusion during solid phase heavy metal tends to occur, which is undesirable.In addition, there is no particular limit on the upper limit of the number average molecular weight of the crystalline polycarbonate prepolymer; 20,000 or less,
Particularly - generally, 10,000 or less are used.

As is clear from structural formula (4), the terminal end of the crystalline polycarbonate prepolymer of the present invention consists of a hydroxyl group and an aryl carbonate group.

There is no particular restriction on the ratio of hydroxyl group to aryl carbonate group, but from the viewpoint of solid phase polymerization rate, it is 98:2 to 2:
98, preferably in the range of 95:5 to 5:95, and particularly preferably in the range of 90:10 to 10:90.

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

If the degree of crystallinity is low, fusion will easily occur, and if it is too high, the polymerization rate will be slow.

Further, there is no particular restriction on the shape of the crystalline polycarbonate prepolymer of the present invention, and it may be in the form of powder, pellet, fiber, or film.

In the present invention, solid phase polymerization is carried out under inert gas flow while removing aromatic monohydroxy compounds such as phenol and diaryl carbonate produced as the polymerization progresses from the system.

In the present invention, an aromatic monohydroxy compound (R represents hydrogen or an alkyl group) is present in the inert gas supplied to solid phase polymerization at a partial pressure of 0.001 to 5 m
Included in the range of sHg.

This aromatic monohydroxy compound is the same as that normally produced during solid phase polymerization, and is contained in the inert gas used in solid phase polymerization. When the partial pressure of the aromatic monohydroxy compound is 5 mm Hg or more, the solid phase supersonant velocity becomes slow and it becomes difficult to obtain a high molecular weight polycarbonate. Further, the partial pressure of the aromatic monohydroxy compound is 0.
If it is lower than 0.001 theoretical Hg, there will be no particular problem in polymerization, but the cost of recovering and reusing the inert gas used in solid phase polymerization will increase, which is industrially unfavorable.

Examples of the inert gas used in the present invention include nitrogen, neon, argon, CO3, etc., and nitrogen is particularly preferred in terms of easy availability.

In the present invention, the flow rate of the inert gas used in solid phase polymerization is preferably in the range of 0.1 to 7 Nf/Hr, more preferably 0.2 to 5 Nffi/Hr per 1 g of crystalline polycarbonate prepolymer. . If the flow rate of the inert gas is lower than this range, the solid phase polymerization rate will be slow. Moreover, if it is larger than this range, the equipment for separating the inert gas from the condensation by-product, such as aromatic monohydroxy compound such as phenol or diaryl carbonate, will become large, which is industrially undesirable.

The solid phase polymerization of the present invention is carried out at a temperature above the glass transition temperature and below the melting point of the crystalline prepolymer, and is 150°C to 26°C.
In the range of 0°C, below 150°C, the polymerization rate is slow, and above 260'C, fusion during solid phase polymerization becomes intense, which is not preferable.

There is no particular restriction on the pressure for solid phase polymerization, and it can be carried out at reduced pressure, normal pressure, or increased pressure, but it has become clear that polymerization can proceed easily even under normal pressure or slightly increased pressure, so it is an inexpensive method. Another feature of the present invention is that it can be easily implemented industrially using equipment.

Various methods are known as solid phase polymerization processes, and any of these methods can be used.

Examples include tumbler type, kiln type, paddle dryer type, screw conveyor type, vibrating type, fluidized bed type, fixed bed type, moving bed type, and the like.

The number average molecular weight of the aromatic polycarbonate obtained by solid phase polymerization is usually 6.000 to 20oo, ooo.

Although solid-phase polymerization can be carried out in the presence or absence of a catalyst, non-catalytic polymerization is preferred because the resulting polymer has much better color, heat resistance, and hot water resistance.

Examples of polymerization catalysts that can be used as needed include various known transesterification catalysts used for polycarbonate or polyester. Examples include alkali metal salts of bisphenol A, tin, and lead compounds. It will be done.

In order to obtain the crystalline polycarbonate prepolymer of the present invention, a method is usually used in which first a non-grade polycarbonate prepolymer is synthesized and then this non-grade polycarbonate prepolymer is crystallized.

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

■ Synthesis by melt polymerization of biphenol such as bisphenol A and diaryl carbonate by transesterification method, ■ Interfacial polycondensation of biphenol and phosgene in the presence of an aromatic monohydroxy compound such as phenol or t-butylphenol as a terminal stopper. Method of synthesis, ■ Molar ratio of biphenol and diaryl carbonate: 1:
A method in which the condensate of 2 is synthesized in advance and this is melt-polymerized with biphenol. ■ In interfacial polycondensation, biphenol is newly added to the phenyl carbonate-terminated polycarbonate oligomer obtained by reacting excess phosgene and phenol with respect to biphenol. Examples include a method of adding and melt polymerizing.

In the present invention, polycarbonate substantially free of chlorine compounds can be obtained.

For example, when a non-grade polycarbonate prepolymer obtained by a transesterification method is used, since there is no chlorine compound in the raw material, a polycarbonate containing no chlorine at all can be produced.

In addition, even if a non-quality polycarbonate prepolymer is produced using phosgene or the like, it is easy to remove chlorine from a low molecular weight amorphous prepolymer. Polycarbonate-free polycarbonate can be obtained.

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 of crystallizing a non-grade polycarbonate prepolymer using an appropriate solvent,
Specifically, there are two methods: (1) dissolving a non-quality polycarbonate prepolymer in a solvent and then precipitating a crystalline prepolymer from this solution; (2) using a solvent with low dissolving power for the prepolymer;
the time required for the solvent to penetrate into the non-grade polycarbonate prepolymer and crystallize the prepolymer;
A method in which the prepolymer is brought into contact with a liquid solvent or solvent vapor is preferably used.

Solvents that can be used for such solvent treatment of prepolymers include, for example, chloromethane, methylene chloride, chloroform, carbon tetrachloride, chloroethane, dichloroethane (various isomers), trichloroethane (various isomers), trichloroethylene, Aliphatic halogenated hydrocarbons such as tetrachloroethane (various isomers); aromatic halogenated hydrocarbons such as chlorobenzene and dichlorobenzene; ethers such as tetrahydrofuran and dioxane; esters such as methyl acetate and ethyl acetate; acetone , ketones such as methyl ethyl ketone; aromatic hydrocarbons such as benzene, toluene, and xylene. Halogen-free solvents are particularly preferred in order to obtain high quality polymers. These solvents may be used alone or in combination of two or more.

On the other hand, heating crystallization method (2) is a method in which the prepolymer is crystallized by heating at a temperature above the glass transition temperature of the target aromatic polycarbonate and below the temperature at which the prepolymer begins to melt. It is. This method can be carried out industrially very easily since the prepolymer can be crystallized simply by holding it under heat.

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 number average molecular weight (1) was measured by gel vermini-silane chromatography.

Further, (2) The ratio of phenyl carbonate groups and hydroxyl groups, which are the terminal groups of the prepolymer, was analyzed by high performance liquid chromatography or NMR.

■Crystallinity is determined by powder x1 diffraction using JP-A-1-1580.
It was measured by the method described in Publication No. 33.

Also, ■The partial pressure of phenol in nitrogen saturated with phenol can be found in "Kagaku Handran" (published by Maruzen in 1980), II-1.
From page 28, it was determined from the phenol vapor pressure using the following formula: % formula %).

Example 1 Bisphenol A and diphenyl carbonate were prepolymerized in a molten state, crystallized by immersion in acetone, and then dried to obtain a number average molecule of 14,100 and a molar ratio of terminal hydroxyl groups of 3.
Using a crystalline polycarbonate prepolymer having a molar ratio of 5%, a terminal phenyl carbonate group molar ratio of 65%, and a crystallinity of 25%, solid phase polymerization was carried out in a glass gas flow reactor with an inner diameter of 15 mm.

The polymerization conditions were as follows: 2 g of powdered crystalline polycarbonate prepolymer was charged with 2 g of nitrogen gas saturated with phenol (phenol partial pressure 0°028 + sHg) at 0°C.
．． Flow at 5Nl/Hr, under normal pressure, from 180℃ to 210''
C for 30 minutes, then raised to 210℃ for 2 hours and 30 minutes.
I kept it. Number average molecule 1111,40 after polymerization time of 3 hours
0 polymer was obtained.

Example 2 and Comparative Example 1 Example 1 except that nitrogen gas saturated with phenol at 50°C (Example 2) and 63°C (Comparative Example 1) was used.
Table 1 shows the results of solid-phase polymerization of the same crystalline polycarbonate prepolymer in exactly the same manner as in Example 1.

The table shows that when the partial pressure of phenol in nitrogen gas was 2.3 mHg, the number average molecular weight increased to 6,800, but when the partial pressure of phenol was 5.7 mHH, the molecular weight hardly increased. .

Example 3 As a crystalline polycarbonate prepolymer, a pellet (diameter l-1 length from 0.5 to 2.0 mm) having a number average molecular weight of 3,980, a molar proportion of terminal hydroxyl groups of 36%, and a crystallinity of 25% was used.
The number average molecular weight of the polymer obtained after 3 hours of reaction was 1.
It was 0,500.

Example 4 As a crystalline polycarbonate prepolymer, number average molecular weight 3,500, terminal hydroxyl group molar ratio 50%,
-20 using a powdered prepolymer with a crystallinity of 23%.
Nitrogen gas saturated with phenol (phenol partial pressure 0.0021 mHg) at 4 Nj! Solid phase polymerization was carried out in exactly the same manner as in Example 1, except that the flow rate was 1/hr. However, the holding time at 21O'C was 7.5 hours. The number average molecular weight of the obtained polymer was 17,400.

Comparative Example 2 Example 4 except that nitrogen gas saturated with phenol at 30°C (phenol partial pressure 0.0004 Hg) was used.
Polymerization was carried out under exactly the same conditions.

After a reaction time of 8 hours, the number average molecular weight of the obtained polymer was 17,600, and the effect of lowering the phenol partial pressure compared to Example 4 was hardly recognized, and the phenol partial pressure was reduced to 0. It was found that there was no need to lower the temperature to 0.0004 mmHg.

The crystalline polycarbonate prepolymer used in Example 3.4 and Comparative Example 2 was prepared by prepolymerizing bisphenol A and diphenyl carbonate in a molten state, crystallizing it by immersing it in acetone, and then drying it. This was obtained by

Example 5 The crystalline polycarbonate prepolymer pellet used in Example 3 was solidified using a 5US304 moving bed continuous gas flow reactor with an inner diameter of 102.3 m and an effective length of 1 m, equipped with an air pump and a gas cooling device. Phase polymerization was performed.

The feeding rate of pellets from the top of the reactor was set at 1.2 kg/
Hr, polymerization temperature was 210℃, and nitrogen gas was 6rrr.
/Hr, the gas discharged from the reactor is cooled to O'C, and then the gas is supplied to the reactor again.
Continuous operation for 0 hours was carried out. 10 hours after start of operation ~2
After 0 hours, the number average molecular weight of the pellets discharged from the lower part of the reactor was in the range of 10,800 to 11,000, and the nitrogen gas could be recovered and reused.

Note that the partial pressure of phenol at 0° C. is 0.028 nmHg from the above formula.

Examples 6 to 9 Using crystalline polycarbonate prepolymers obtained by prepolymerizing bisphenol A1 diphenyl carbonate and various dihydroxydiaryl compounds and subsequently crystallizing them, solidification was performed in exactly the same manner as in Example 1. Phase polymerization was performed.

The results are summarized in Table 2.

(Effects of the Invention) In the present invention, when solid-phase polymerizing a crystalline polycarbonate prepolymer, an inert gas containing an aromatic monohydroxyl compound is used under specific p conditions. High quality polycarbonate can be easily produced.

(1 other person)

Claims (1)

[Claims] (1) General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, X is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ is -A
rOH, and Y represents -OH or ▲numerical formula, chemical formula, table, etc.▼ group. Here, R represents hydrogen or an alkyl group, Ar represents an aromatic residue, and n represents the number of repeats. ) in the inert gas supplied when solid-phase polymerizing a crystalline polycarbonate prepolymer with a number average molecular weight of 1,500 or more at a temperature range of 150 to 260°C under inert gas flow. , chemical formulas, tables, etc. The partial pressure of ▼ is 0.001 to 5
A method for solid-phase polymerization of polycarbonate, characterized in that the temperature is in the range of mmHg.