JPH04189834A - Production of polycarbonate granular substance - Google Patents

Abstract

PURPOSE:To obtain the subject granular substance, excellent in processability and handleability and useful for extrusion molding, etc., by introducing a polycarbonate granular substance containing a prescribed amount or more of an organic solvent in an atmosphere at a temperature above the glass transition temperature, vaporizing the organic solvent and providing a bulk density within a specific range. CONSTITUTION:For example, a polycarbonate granular substance containing >=20wt.% organic solvent such as methylene chloride is introduced into an atmosphere kept at a temperature above the glass transition temperature of the polycarbonate constituting the aforementioned granular substance (the temperature is preferably 140-180 deg.C) to vaporize the organic solvent contained in the above-mentioned granular substance with, e.g. a paddle type dryer and the bulk density of the aforementioned granular substance is regulated to 0.35-0.7g/cm<3>. Thereby, the objective granular substance is obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing polycarbonate powder, and more specifically, to a method for producing polycarbonate powder, which has high density, excellent drying properties, processability, and handling properties. Regarding manufacturing methods.

<Prior art> Polycarbonate is usually obtained as an organic solvent solution of polycarbonate by reacting dihydric phenol and a carbonate precursor in the presence of an organic solvent, and the organic solvent is removed from this organic solvent solution to obtain polycarbonate powder. It is then dried to remove residual organic solvents and moisture, and then used for molding. It is preferable that the powder to be subjected to molding has a high bulk density, good fluidity (small angle of repose), little fine powder, and little organic solvent and moisture.

As a method for obtaining polycarbonate powder from an organic solvent solution, the organic solvent solution of polycarbonate is appropriately concentrated to gel or crystallize to make it easier to crush, pulverize, and dry at a temperature of 120 to 140°C. Method for removing solvents and water (Japanese Patent Publication No. 36-21033, Japanese Patent Publication No. 38
-22497 Publication, Special Publication No. 1979-12379,
Special Publication No. 45-9875, Special Publication No. 46-31468
Publication No.) is known.

However, although gelled or crystallized and pulverized products have a high bulk density, since there are almost no pores in the powder, large particles have poor drying efficiency, and It takes a very long time to sufficiently remove volatile components (organic solvents and moisture). In order to improve this drying efficiency, it is necessary to pulverize the powder or granules. However, when pulverized powder dries, electrostatic adhesion to the walls of the equipment becomes significant.
This may reduce drying efficiency and cause powder to fuse, causing trouble. In addition, many problems arise in handling, processability, hygiene due to dust generation, stability of extrusion molding, etc. when subjected to processing.

<Object of the Invention> An object of the present invention is to provide polycarbonate powder having a large bulk density and excellent drying properties, processability, and handling properties.

In order to achieve the above object, the present inventor made extensive inquiries into the manufacturing method of polycarbonate powder and found that polycarbonate powder containing a specific amount or more of an organic solvent was placed in an atmosphere maintained at a temperature higher than the glass transition temperature. By adding it to the powder, appropriate pores are generated inside the powder.
The present invention was achieved by discovering that residual solvent and water can be efficiently removed in the drying process without significantly reducing the density.

<Structure of the Invention> In the present invention, polycarbonate powder containing 20% by weight or more of an organic solvent is placed in an atmosphere maintained at a temperature equal to or higher than the glass transition temperature of the powder. The organic solvent contained in the powder is vaporized to reduce the bulk density of the powder to 0.
35 to 0.79/d is a method for producing polycarbonate powder.

The polycarbonate powder used in the present invention may be produced by any method, but is particularly obtained by a so-called solution method in which dihydric phenol and carbonate precursor are reacted in the presence of an organic solvent. Particles obtained from an organic solvent solution by, for example, gelation by concentrating the solution or gelation by adding a non- or poor solvent are preferable because they inherently contain an organic solvent.

The dihydric phenol mentioned above is mainly 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), but part or all of it may be replaced with other dihydric phenols.

Other dihydric phenols include, for example, hydroquinone, 4
, 4-dihydroxydiphenyl, bis(4-hydroxydiphenyl)methane, 1.1-bis(4-hydroxyphenyl)ethane, 2.2-bis(4-hydroxyphenyl)butane, 1-phenyl-1,1-bis (4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ketone,
Bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl)
-hydroxyphenyl) sulfone or lower alkyl or halogen substituted products thereof.

Examples of carbonate precursors include carbonyl halides, carbonyl esters, heroformates, etc., and specific examples include phosgene, diphenyl carbonate, and dihaloformates of dihydric phenols.

Polycarbonates obtained from these dihydric phenols may be used alone or as a mixture of two or more types of polycarbonates, and even polycarbonates that cannot be produced by gelling powder processing can be gelled by mixing with the above polycarbonates. If so, it can be applied.

Examples of the organic solvent contained in the polycarbonate powder include methylene chloride, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, tetrachloroethane, chlorobenzene, and mixtures thereof. In addition, a non- or poor solvent such as acetone, heptane, hexane, etc. may also be contained.

Organic solvent concentration W contained in polycarbonate powder
Weight % is expressed by the following formula, where X is the amount of polycarbonate in the powder, Y is the amount of organic solvent in the powder, and 7 is the amount of water in the powder.

W=(Y)x100/(X+Y+Z)≧20, preferably 30 to 60% by weight. When the organic solvent content is less than 20% by weight, pores are not sufficiently generated inside the powder and the drying efficiency is difficult to improve. In addition, if the amount is too large, it becomes difficult to handle as powder or granules.

Polycarbonate powder containing an organic solvent can be obtained by any method, but for example, an organic solvent solution obtained by reacting a dihydric phenol and a carbonate precursor in the presence of an organic solvent is sufficiently purified. A preferred method is to pour the mixture under stirring into a kneader containing warm water at a temperature slightly higher than the boiling point of the organic solvent, thereby concentrating it into a gel.

The polycarbonate powder containing an organic solvent is pulverized with a pulverizer or the like in order to have an appropriate particle size as necessary, and then placed in a container maintained at a temperature equal to or higher than the glass transition temperature of the polycarbonate. By doing so, the temperature of the granular material is rapidly raised, the organic solvent inside the granular material is rapidly vaporized, and pores are generated inside the granular material.

If the temperature of the atmosphere into which the powder is introduced is lower than the glass transition temperature of polycarbonate, the formation of pores will be significantly reduced, making it impossible to achieve the object of the present invention. The upper limit of the atmospheric temperature to be charged depends on the processing time, stirring conditions during processing, etc. - Although it cannot be generally specified, the preferable temperature is 140~
The temperature is 180°C. If the processing time is too short, the amount of pores formed inside the powder or granules will be reduced, so it is usually 1 minute or more, preferably 10 minutes or more, and when drying is subsequently performed in this atmosphere, the treatment time is 5 to 7 o'clock. It is preferable to carry out fjjl￥ degree.

By the hot water treatment described above, the bulk density of the powder or granule is determined by A, which is the bulk density of the powder or granule before heat treatment, and B, which is the bulk density of the powder or granule after high temperature treatment.
Then, normally A-8≧0.04 (g/Cl11'). That is, the high density is reduced by 0.04 g/Cwl' or more by the a-water treatment, and the target IIM density is 0.35 to 0.7 g/c.
Powder d is obtained. Particles with a bulk density higher than 0.79/Cd do not generate sufficient pores and do not improve drying efficiency. In addition, if the density is lower than 0.35y/, -,1', the drying efficiency will improve, but the fluidity, handling, and storage properties will be poor, and the stability during processing will also deteriorate, making it impractical. .

The equipment used for high-temperature treatment may be any equipment as long as it can rapidly raise the temperature of the granular material, such as equipment with an agitator such as a paddle dryer, rotating equipment such as a rotary kiln, equipment such as a jacketed mixer, or an inert equipment. A variety of devices can be used for fluidizing devices using gas hot air. Additionally, these devices may be used in combination. Various types of heat medium are used in these devices, including superheated steam, indirect heating using far infrared rays, and electron beams. Further, the processing means may be either a batch type or a continuous type.

<Effects of the Invention> According to the present invention, polycarbonate powder having a large bulk density and excellent drying properties, processability, and handling properties can be easily produced.

<Example> The present invention will be explained in further detail by giving examples below.

In addition, the measurement is based on the following method.

■Solvent concentration (weight %): The organic solvent concentration W weight i% contained in the polycarbonate powder is determined by the amount of polycarbonate in the powder being X, the amount of organic solvent in the powder being Y, the powder If the amount of water in the body is 7, it is expressed by the following formula.

W=Yx 100/ (X0Y+Z) Amount of solvent (methylene chloride) Before heat treatment: After thermally decomposing the sample with Ha leaf solution,
CI analysis is performed using a conventional method, and the amount is converted into methylene chloride.

After heat treatment: Total organic halogen analyzer (TO manufactured by Mitsubishi Kasei)
C! Analyze and convert into methylene chloride amount.

Polycarbonate amount: 140% of wet sample before heat treatment
Dry under reduced pressure at ℃ for 24 hours, and use the remaining amount as polycarbonate.

Moisture I (1% by weight): When the sample amount (polycarbonate powder or granules) is U, the amount of polycarbonate in the powder or granules is X, the amount of organic solvent in the powder or granules is Y, and the amount of water in the powder or granules is 7. , is expressed by the following equation.

Z-[U-(X+Y)] x 100/Ll■
Bulk 1! ! Il! Before heat treatment = powder dried at normal pressure for 48 hours at 120℃
Measure according to IS K-6721.

After heat treatment: Heat-treated powder and granules are JISK-67 as they are.
Measure according to 21.

Example 1 Viscosity average molecular weight 25.3 obtained by reacting bisphenol A with phosgene in the presence of methylene chloride and thoroughly purifying it.
00 polycarbonate solution (concentration 15% by weight) 10
25 degrees Celsius was added to a kneader with a capacity of 500 and Q, which had been charged with 50 tons of warm water at 40 to 42 degrees Celsius in advance, and the liquid temperature was 40 to 42 degrees Celsius while stirring.
with steam at a vapor pressure of 3 Ky/d at a rate that maintains the temperature at 1
．． It was dried for 5 hours to obtain powder.

This granular material was pulverized with a hammer mill and centrifugally dehydrated to obtain a polycarbonate granular material (glass transition temperature: 150° C.) containing 52% by weight of methylene chloride and 5% by weight of water.

This granular material is placed in the jacket in advance at a vapor pressure of 5.5 kg.
/cIi water vapor was passed therethrough, and heat treatment was carried out at a flow rate of 100μ,/hr, by continuously charging the product into a two-shaft paddle dryer with a capacity of 25ρ and having an overflow port, which was heated to 155°C. The residence time was set at 15 minutes. The heat-treated powder was further dried with hot air at 140°C and 155°C for 5 hours, respectively. Table 1 shows the methylene chloride content, high density, and pore state of the obtained granules.

Example 2 Viscosity average molecular weight 22.0 obtained by reacting bisphenol A with phosgene in the presence of methylene chloride and thoroughly purifying it.
00 polycarbonate solution (11 degrees 15% by weight),
As in Example 1, polycarbonate powder (glass transition temperature: 150 DEG C.) containing 48% by weight of methylene chloride and 5% by weight of water was obtained through kneader, hammer mill, and centrifugal dehydration.

This granular material is placed in the jacket in advance at a vapor pressure of 5.5'.
Heat treatment was carried out by continuously introducing water vapor at a rate of 10 ρ/hr into a twin-shaft paddle dryer having a capacity of 50 i and having an overflow port heated to 160° C. through water vapor at a rate of 10 ρ/hr.

The residence time was 5 hours and no drying was necessary in this case. Table 1 shows the methylene chloride content, high density, and pore state of the obtained granules.

Example 3 The same procedure as Example 2 was carried out except that the jacket temperature of the paddle dryer was set to 170°C. The results are shown in Table 1.

Example 4 Two 25-degree paddle dryers are connected, and the jacket temperature of the first machine is 160°C, and the jacket temperature of the second machine is 140°C.
The same procedure as in Example 2 was carried out except that the temperature was adjusted to 0.degree. C. and the residence time in each case was changed to 2 hours and 30 minutes. The results are shown in Table 1.

Example 5 A granular material containing methylene chloride of 1t60@ω% was obtained in the same manner as in Example 2, except that the temperature of the kneader was set to 39 to 41°C. Using this powder, the jacket temperature of a paddle dryer was adjusted. The heat treatment was carried out in the same manner as in Example 2 except that the temperature was 170°C. The results are shown in Table 1.

Example 6 2J of the powder containing 52% by weight of methylene chloride and 5% by weight of water used in Example 1 and 80 grams of acetone were mixed in a volume of 15%.
After acetone treatment by stirring for 20 minutes in a 0μ stirrer-equipped container, the powder was deliquified using a centrifugal separator and placed in a paddle dryer heated and maintained at a jacket temperature of 160°C, where it was heat-treated for 5 hours. . The results are shown in Table 1.

Comparative Example 1 The same conditions as in Example 1 were carried out except that the jacket temperature of the paddle dryer was 140°C. As shown in Table 1, the results showed that the methylene chloride content was significantly high and the number of pores in the powder was very small.

Comparative Example 2 The same procedure as in Example 2 was carried out except that the jacket temperature of the paddle dryer was 140°C. As shown in Table 1, the results showed that the methylene chloride content was high and the pores in the powder were very small.

Comparative Example 3 The same procedure as in Example 6 was carried out except that the jacket temperature of the paddle dryer was 140°C. As shown in Table 1, the results showed that the methylene chloride content was high and the pores in the powder were very small.

(Margin below) Procedural amendment July/7th, 1991

Claims (1)

[Claims] Polycarbonate powder containing 20% by weight or more of an organic solvent is placed in an atmosphere maintained at a temperature higher than the glass transition temperature of the powder to vaporize the organic solvent contained in the powder. The bulk density of the powder is set to 0.35 to 0.
A method for producing polycarbonate powder, characterized in that the particle size is 7 g/cm^3.