JPH08104758A - Powdery polycarbonate and production thereof - Google Patents

Abstract

PURPOSE: To obtain a powdery polycarbonate which has high bulk specific gravity and degree of crystallinity and provides a molding excellent in color tone by selecting a specific powdery polycarbonate. CONSTITUTION: A powdery polycarbonate is selected which has been crystalized at least partially, is produced pref. by reacting a dihydric phenol with COCl2 or a carbonic ester compd., and has a viscosity-average mol.wt. of 10,000 or higher, a crystal m.p. of 255 deg.C or higher, and pref. a heat of melting of 25mJ/mg or higher. The polycarbonate is obtd. from a polycarbonate soln. in an org. solvent (e.g. methylene chloride) by removing the solvent by evaporating it at a temp. in the range of from 20 deg.C lower to 40 deg.C higher than the b.p. of the solvent at an evaporation rate of 10kg/hr or lower based on 1kg of the polycarbonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate powder and a method for producing the same, and more particularly to a polycarbonate powder having a high crystal melting point and an improved color tone, and a method for producing the same.

[0002]

2. Description of the Related Art As a method for producing polycarbonate, there are a melt polycondensation method (ester exchange method) and an interfacial polycondensation method (phosgene method). In general, the latter interfacial polycondensation method is predominant in industry. . In the interfacial polycondensation method, an alkaline aqueous solution of dihydric phenol and phosgene are usually reacted in the presence of an organic solvent to remove the organic solvent from an organic solvent solution of polycarbonate, and a drying step is performed to obtain a granular material. Conventionally, various methods have been studied as methods for obtaining polycarbonate powder particles from a solution of polycarbonate in an organic solvent. For example, a method in which a methylene chloride solution of polycarbonate is poured into warm water or hot water (Japanese Patent Publication No.
6-37424, Japanese Patent Publication No. 4-71412).
There is. However, the powder obtained by this method has a low bulk specific gravity, and since the biting speed of the polycarbonate particles into the extruder during extrusion is low, the oxygen concentration in the extruder becomes high and the color tone tends to deteriorate. . Further, a polycarbonate powder having a low bulk specific gravity generally has a crystal melting point (T
m) was also low, and the crystalline melting point of the polycarbonate powder obtained by this method was at most about 230 ° C. As a polycarbonate powder having a relatively high crystal melting point,
Grinding method using a kneader utilizing crystallization (JP-A-60-
115625, JP-A-4-189835,
JP-A-4-266930). However, the crystalline melting point is not necessarily high enough even in the powder or granules obtained by these methods, and moreover, the powder or granules to be seeds are charged in advance and contacted with an organic solvent solution of polycarbonate with stirring. However, there is also a drawback in that it takes time to replace the target powder in order to obtain a granular material. Crystallization with a poor solvent or non-solvent has also been attempted, but a large amount of solvent remains in the powder and granules obtained by this method, and it is difficult to remove it even in the drying step, resulting in poor color tone and poor thermal stability. There is a drawback that it is easy to generate.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a polycarbonate having a high bulk specific gravity, a high crystallinity and an excellent color tone when formed into a molded product.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its gist is a polycarbonate powder granulated at least in part. A crystalline powder having a crystalline melting point of 255 ° C. or higher, and a method for producing a polycarbonate powder by removing the organic solvent from an organic solvent solution of the polycarbonate, the organic solvent of polycarbonate The organic solvent is evaporated and removed from the solution at a temperature of 20 ° C. to 40 ° C. lower than the boiling point of the organic solvent at 1.0 kg / Hr or less relative to 1 kg of polycarbonate solid content, and a crystal melting point is 255 ° C. or more. A method for producing a polycarbonate powder is characterized in that a polycarbonate powder is obtained.

The present invention will be described in detail below. The type of polycarbonate in the polycarbonate powder or granule targeted by the present invention is not particularly limited, and it is obtained by a usual polycondensation reaction, and is obtained by the reaction of a dihydric phenol with phosgene or a carbonate compound. Various polycarbonates can be used. Examples of the dihydric phenol include hydroquinone;
4,4′-dihydroxydiphenyl; bis (4-hydroxyphenyl) alkane; bis (4-hydroxyphenyl) cycloalkane; bis (4-hydroxyphenyl)
Oxide; bis (4-hydroxyphenyl) sulfide; bis (4-hydroxyphenyl) sulfone; bis (4-hydroxyphenyl) ketone and the like, and halogen-substituted compounds thereof. Examples of the carbonic acid ester compound include diaryl carbonate such as diphenyl carbonate and dialkyl carbonate such as dimethyl carbonate and diethyl carbonate. And
For example, according to the phosgene method, most commonly, by reacting bisphenol A and phosgene in an inert solvent such as methylene chloride (methylene chloride) in the presence of a tertiary amine (such as treethylamine) catalyst, Obtainable. The polycarbonate in the present invention has a viscosity average molecular weight of 100 obtained by reacting a divalent phenol with phosgene or a carbonate compound.
A polycarbonate of 00 or more, more preferably 15,000 or more is preferable.

At least a part of the polycarbonate powder in the present invention is crystallized, and the crystallized polycarbonate has a melting point of 255 ° C. or higher. Further, the polycarbonate powder or granular material in the present invention has a high melting point and high crystallinity, and has a melting point of 255 ° C.
The above and the heat of fusion of 25 mJ / mg or more are preferable. Such a crystallized polycarbonate can be obtained by controlling the evaporation rate of the organic solvent from a solution of the polycarbonate in an organic solvent to a specific value or less.

The organic solvent used in the present invention is substantially inert to polycarbonate,
Any material that dissolves polycarbonate may be used. In addition to methylene chloride which is usually used preferably, chloroform, chlorobenzene and other chlorine-based solvents, benzene, toluene, xylene, acetone, methyl ethyl ketone, ethyl acetate, dioxane, tetrahydrofuran and other solvents, or a mixture thereof, or substantially Aliphatic alkanes such as heptane, hexane, pentane, etc., which have been mixed without problem in dissolving in, may be mixed.
And these solvents may contain a poor solvent to the extent that the polymer does not precipitate. Here, as the poor solvent,
Aromatic compounds such as benzene, toluene, xylene, alkanes such as pentane, hexane, heptane, octane, etc.
It is a ketone such as acetone or methyl ethyl ketone, or a mixed solvent thereof.

The concentration of the polycarbonate dissolved in the above solvent is 5 to 60% by weight, preferably 10 to 40% by weight.
Is appropriate. If the concentration is less than 5% by weight, it takes time to form the powder and granules, and the amount of the solvent to be recovered increases, which lowers the productivity and is not efficient. On the other hand, if it exceeds 60% by weight, it becomes solid and the fluidity becomes low, and the operation becomes difficult, which is not preferable.

An organic solvent solution of polycarbonate prepared by using the above-mentioned organic solvent is put into a container equipped with an evaporation removing device capable of uniformly stirring. The container is not particularly limited as long as it can uniformly stir the organic solvent solution of the polymer. For example, kneader,
A Nauter mixer, a tumbler, etc. are preferably used. It is not necessary to pre-fill the container with polymer powder or granules that will be seeds. With this method, it is possible to obtain the desired powder and granules from the beginning, and there is a feature that seed replacement is not required, and various methods such as batch method, continuous method, and semi-continuous method can be adopted.

The container jacket temperature is 20 ° C. to 40 ° C. lower than the boiling point of the organic solvent, and 20 ° C. to 40 ° C. higher than the low boiling point in the mixed solvent system, preferably higher than the high boiling point. A temperature near the boiling point is suitable, and for example, in the case of methylene chloride, a jacket temperature near 40 ° C. is suitable. If this temperature is too low, the evaporation rate of the organic solvent will be slowed down, resulting in reduced productivity and inefficiency. On the other hand, if it is too high, large lumps are likely to be formed, and it is difficult to obtain the intended powder or granules. Further, it can be carried out under reduced pressure to promote the evaporation of the organic solvent, but if it is too high, it is difficult to obtain a granular material having a uniform particle size, and the bulk specific gravity and the crystallinity are low and the color tone is also preferable. Absent. As described above, control of the evaporation rate of the organic solvent is extremely important in order to obtain the intended powder or granular material. The evaporation rate of the organic solvent is 1 polymer solids.
It is 1.0 kg / Hr or less with respect to kg.

Since the powder and granules obtained as described above contain a large amount of residual solvent, they are dried. Any dryer is used for drying, and examples thereof include a fluidized dryer, a paddle dryer, and a hot air dryer. The drying conditions are not particularly limited, but when an organic solvent or a poor solvent is contained, it is preferable to dry at a temperature of the highest boiling point or higher, preferably about 120 to 150 ° C. The drying time is usually 30 minutes or longer, preferably about 60 minutes to 24 hours.

[0012]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples unless it exceeds the gist thereof. The measurement was performed by the following method. (A) Bulk specific gravity ρB: It was measured according to JIS K-6721 using a bulk specific gravity measuring device [manufactured by Kuramochi Kagaku Kikai].

(B) Crystal melting point Tm and heat of fusion ΔH: DS
Using C-200 [manufactured by SEIKO], a sealed Al cell was used and scanning was performed at 20 ° C./min. ΔH was calculated from the following equation, where the peak temperature of the endothermic peak was Tm. Metals with clear literature values (In, Sn, P
b, Zn) and the reference value ΔHr
The apparatus constant K at the transition temperature of each standard substance was calculated from ef.

[0014]

[Equation 1] Ki = ΔHref · i / ΔHcal · i × C

Here, Ki is a device constant (μW) at the transition temperature of the standard substance i ΔHref · i: A reference value of ΔH of the standard substance i (mJ / m)
g) ΔHcal · i: Calculated value of standard substance i (mJ / mg) C: DSCspan value (μW) From the set of transition temperature Ti of each standard substance and device constant Ki, the device constant K (T) is expressed in the following form. Each coefficient was calculated by regressing into a quadratic equation of temperature.

[0016]

## EQU2 ## K (T) = C × (1 + dT + eT ² )

The obtained values of C, d, and e are respectively DSCs.
Input to pan, 1dimcal, 2dimcal.
In case of Al cell DSCspan, 1dimcal, 2d
imcal had the following values. ^{DSCspan: 1.361 × 10 5 1dimcal:} 1.070 × 10 3 2dimcal: 0.000 × 10 0

(C) Plate YI: injection molding machine [NISSEI F
S80S12ASE type] and diameter of 50mm at 290 ° C
A plate plate having a thickness of 3 mm is molded, and a color difference meter [manufactured by Suga Test Instruments Co., Ltd.] is used to measure JIS K-7105-Z 8722
The measurement was performed according to the standards. The smaller the value, the smaller the yellow tint. As an organic solvent solution of polycarbonate, a methylene chloride solution of polycarbonate having a viscosity average molecular weight of 30,000 (hereinafter referred to as PCM) obtained from bisphenol A and phosgene and a methylene chloride solution of a polycarbonate having a viscosity average molecular weight of 21,000 were concentrated by an evaporator to 30% by weight. I used one.

Example 1 A universal mixing stirrer 5DMV-01-Qr manufactured by Dalton Co., Ltd. was used, and a viscosity average molecular weight of 300 was used.
When 30 liters of PCM (3.5 liters) of 00 was charged and stirred at atmospheric pressure with a jacket temperature of 40 ° C., nitrogen was blown at 1.0 L / Hr and stirred for about 6 hours (methylene chloride removal rate 0.50 kg / Hr) Polycarbonate powder was obtained. The powder and granules were dried by a hot air circulation dryer at 100 ° C. for 24 hours and then by a vacuum dryer.
It was dried at 43 ° C. for 24 hours to obtain the desired product.

Example 2 The same operation as in Example 1 was carried out except that 30% by weight PCM having a viscosity average molecular weight of 21,000 was used in Example 1.

Comparative Example 1 The same operation as in Example 1 was carried out except that the gauge pressure was −150 mmHg (about 8 × 10 ⁵ Pa) and the jacket temperature was 60 ° C. A polycarbonate powder granule was obtained after stirring for about 3 hours (methylene chloride removal rate: 1.2 kg / Hr).

Comparative Example 2 The same operation as in Example 1 was carried out except that the gauge pressure was −300 mmHg (about 6 × 10 ⁵ Pa) and the jacket temperature was 40 ° C. A polycarbonate powder granule was obtained after stirring for about 3 hours (methylene chloride removal rate: 1.2 kg / Hr).

Comparative Example 3 In Example 1, when the jacket temperature was set to 90 ° C. under atmospheric pressure, a large lump was formed after 1 hour (methylene chloride removal rate 2.5 kg / Hr).
It became impossible to operate.

[Comparative Example 4] The same operation as in Example 1 was carried out except that the gauge pressure was -300 mmHg (about 6 x 10 ⁵ Pa) and the jacket temperature was 40 ° C. A polycarbonate powder granule was obtained after stirring for about 3 hours (methylene chloride removal rate: 1.2 kg / Hr). Table 1 shows the measurement results of the polycarbonate powder particles obtained in the examples and comparative examples.

[0025]

[Table 1]

[0026]

According to the present invention, it is possible to obtain a polycarbonate powder granule having a high bulk specific gravity, a high crystallinity and an improved color tone.

Claims (6)

[Claims] 1. A polycarbonate powder having at least a part thereof crystallized, wherein the powder has a crystal melting point of 255.
A polycarbonate powder granule characterized by having a temperature of ℃ or higher. 2. The polycarbonate powder or granular material according to claim 1, wherein the heat of fusion of the polycarbonate powder or granular material is 25 mJ / mg or more. 3. A method for producing a polycarbonate powder by removing the organic solvent from an organic solvent solution of polycarbonate, comprising: heating the solution from the organic solvent solution of polycarbonate at a temperature 20 ° C. lower than the boiling point of the organic solvent;
Polycarbonate powder particles having a crystalline melting point of 255 ° C. or higher by evaporating and removing the organic solvent at a temperature of 0 ° C. higher than 1.0 kg / Hr with respect to 1 kg of polycarbonate solid content Body manufacturing method. 4. The method for producing a polycarbonate powder or granular material according to claim 3, wherein the organic solvent solution of the polycarbonate is mixed with stirring. 5. The method for producing a polycarbonate powder or granular material according to claim 3, wherein the concentration of the polycarbonate in the polycarbonate organic solvent solution is 5 to 60% by weight. 6. The polycarbonate powder according to claim 1, wherein the polycarbonate is a polycarbonate having a viscosity average molecular weight of 10,000 or more obtained by the reaction of a dihydric phenol with phosgene or a carbonate compound. Grain.