JPH04189835A - Production of polycarbonate granular substance - Google Patents

Abstract

PURPOSE:To obtain the subject granular substance, having a high bulk specific gravity and excellent in transportability by feeding a solution of a polycarbonate in an organic solvent to a granular substance of a polycarbonate during flowing at a higher temperature than the boiling point of the organic solvent in an atmosphere without containing moisture and evaporating the organic solvent. CONSTITUTION:A polycarbonate granular substance is produced from a solution of the polycarbonate in an organic solvent such as methylene chloride. In the aforementioned process, a solution of the polycarbonate in an organic solvent (the concentration is preferably 5-25wt.%) is fed to the polycarbonate granular substance flowing at a temperature, e.g. 100-150 deg.C which is higher than the boiling point of the aforementioned organic solvent in an atmosphere substantially without containing moisture to evaporate the organic solvent. Thereby, the objective granular substance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polycarbonate particles from a solution of polycarbonate in an organic solvent.

[Prior Art and Problems to be Solved by the Invention] Conventionally, the following method is known as a method for extracting polycarbonate powder from an organic solvent solution of polycarbonate.

1) A method in which an organic solvent solution of polycarbonate is added together with a precipitant into a mixing tank in which stirring is carried out, and the polycarbonate is precipitated as a fine powder, or the resulting lumps are crushed with a bladed stirring blade. 224
47, Special Publication No. 37-7000, Special Publication No. 46-37424
), the powder obtained by this method has a small bulk specific gravity (
0.23 to 0.38), it is less economical to store and transport, and has the disadvantage that it is difficult to handle because the product becomes a fine powder. In addition, increasing the concentration of the polycarbonate solution in an organic solvent has the disadvantage that it becomes difficult to operate and the workability is low.

2) Method of powdering by passing a polycarbonate solution in an organic solvent together with steam in a turbulent flow (Japanese Patent Publication No. 40-3533)
, Special Publication Sho 4O-9843). This method also has the same drawbacks as method 1) in that the bulk specific gravity of the powder obtained is at most 0.38, and it is difficult to handle because it becomes a fine powder.

3) A method for obtaining polycarbonate granules by supplying a polycarbonate solution and aquatic plants into a container containing uniformly stirred polycarbonate granules, and evaporating the 1R18 medium (Japanese Unexamined Patent Publication No. 162753/1989). This method is said to yield polycarbonate granules with a bulk specific gravity of 0.3 to 0.6, but the resulting polycarbonate granules each contain about 10% or more of organic solvent and water. Therefore, there is a drawback that a large amount of energy and time are required for subsequent drying. Furthermore, since water vapor is used, expensive corrosion-resistant materials are required to be selected from the viewpoint of corrosion, which increases equipment costs.Furthermore, the recovery of the solvent requires separation from water.

[Means for Solving the Problems] The present inventors have solved the above-mentioned problems, namely, that polycarbonate granules obtained from an organic solvent solution of polycarbonate are dry products that do not contain water or organic solvents.
It satisfies various conditions such as having a large bulk specific gravity and being easy to handle, being able to directly distill and recover the solvent without using poor solvents, etc., and being able to easily perform continuous operation on a large scale, and using capable machinery and inexpensive materials. We have conducted intensive research on a method for producing polycarbonate granules from a solution of polycarbonate in an organic solvent. As a result, in isolating polycarbonate as granules from the organic solvent f4'1& of polycarbonate, the present inventors constantly fluidized the polycarbonate granules and transferred the fluidized polycarbonate granules to the organic solvent of the polycarbonate organic solvent solution. Set the temperature above the boiling point of the solvent. Furthermore, the inside of the apparatus is made into an atmosphere substantially free of moisture, and the flowing polycarbonate granules contain polycarbonate. solvent f
If 4 Wft is supplied by spraying or dripping,
Yes! The solvent evaporates, and the polycarbonate particles that were initially introduced become a medium, and the organic solvent evaporates and the isolated polycarbonate is coated on the polycarbonate particles existing in the device. As the particles grow, it was discovered that dried polycarbonate granules having a certain favorable particle size range could be obtained, and the present invention was completed.

That is, the present invention provides a method for producing polycarbonate granules from a solution of polycarbonate in a medium, in which a solution of a polycarbonate in an organic solvent is heated in an atmosphere substantially free of water from the boiling point of the organic solvent. fed into polycarbonate granules flowing at high temperatures,
This method of producing polycarbonate is characterized by taking out granular polycarbonate by evaporating an organic solvent.

The present invention will be explained in more detail below.

The polycarbonate solution targeted by the present invention is prepared by reacting a dihydroxydiaryl compound with phosgene or a bischloroformate of a dihydroxydiaryl compound in the presence of an acid binder and an organic solvent that dissolves the polycarbonate according to a well-known method. Examples include the obtained polycarbonate solution or a solution obtained by appropriately concentrating the same, but solutions prepared by other methods may also be used.

The concentration of the polycarbonate solution can range from a low concentration to a saturated solution, but it is usually best to select a polycarbonate concentration of 5% or more, and in the above reaction, the polycarbonate concentration of 4% is usually 5% to 5%. Since a polycarbo2-)i@ liquid of about 25% by weight is obtained, it is best to use it as is.

As for dihydroxysoaryl compounds, -maximum % formula % [in the formula,
- or one side, a divalent group represented by -, R is a hydrogen atom,
Monovalent hydrocarbon residues or halogen atoms may be the same or different. R' is 2
Indicates the hydrocarbon residue of the valence. ] is a dihydroxydiaryl compound represented by

Specifically, bis(4-hydroquinphenyl)methane,
1,1-bis(4-hydroxyphenyl)ethane, 2.
2-bis(4-hydroquinphenyl)propane, 2゜2
-His(4-hydroquinphenyl)butane, 2,2-bis(4-hydroxyphenylnooctane, bis(4-hydroquinphenyl)phenylmethane, 2,2-bis(4-hydroxyphenyl)butane,
-hydroxy-3-methylphenyl)propane, 1.1
-bis(4-hydroxy-3-tert-butylphenyl)propane, 2.2-bis(4-hydroxy-3-bromophenyl)propane, 2.2-bis(4-hydroxy-3-bromophenyl)propane
15~nobromophenyl)propane, 2,2-bis(4
-bis(hydroxyaryl)alkanes such as hydroxy-3,5-dichlorophenyl)propane, 1.1
-bis(4=hydroxyphenyl)cyclopentane, 1
, bis(4-hydroxyaryl)cycloalkanes such as 1-bis(4-hydroxyphenyl)noclohexane, 4,4'-dihydroquinodiphenyl ether, 4
, 4"-dihydroquine-3,3"-dihydroxydiarylethers such as dimethyldiphenyl ether;
4,4″-dihydroxydiphenyl sulfide, 4,4
dihydroxydiaryl sulfides such as ゛-dihydroquino-3,3゛-dimethyldiphenyl sulfide;
4.4'-dihydroxydiphenyl sulfoxide, 4,
Dihydroquinodiaryl sulfokides such as 4′-dihydroxo-3,3′-dimethyldiphenyl sulfoxide, 4,4′-dihydroquinodiphenylsulfone, 4
, 41-dihydroxy-3,3'-dimethyldiphenylsulfone and other dihydroquine diarylsulfones.

These can be used alone or in a mixture of two or more,
In addition to these, hydroquinone, resorcinol, 4,4゛-
Dihydroxydiphenyl and the like may be used in combination.

Examples of solvents for dissolving polycarbonate include methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2-trichloroethane, tetrachloroethane, chlorhenzene, etc., or mixtures thereof. , those having a low boiling point that can dissolve polycarbonate well are preferred, and methylene chloride is preferred.

Examples of the acid binder include caustic alkalis such as caustic soda and caustic potash, and bases such as pyridine.

In the method of the present invention, various types of equipment commonly used for drying and mixing powder or granular materials can be used as the device for evaporating the J11 solvent in the organic solvent solution of polycarbonate, such as a fluidized bed or a transfer fluidized bed. It is preferable to use bed and vibrating fluidized bed type dryers, rotary drum mixers, kneaders, paddle mixers, ribbon dryers, stirring tanks, and the like.

The degree of fluidity of the polycarbonate granules is sufficient as long as it is sufficient to mix each particle. The particle size of the initially charged polycarbonate granules is 10 mm or less, preferably 0.
．． 1 to 411IllII11 are used.

The temperature of the polycarbonate granules is maintained at a temperature higher than the boiling point of the organic solvent, and the pressure inside the device is reduced from vacuum to 5 kg/kg.
For ease of operation, it is preferable to operate the pressure within the range of cilT -G, preferably at normal pressure. Furthermore, it is preferable in terms of product quality to constantly supply an inert gas, such as nitrogen or carbon dioxide gas, into the apparatus. If an organic solvent solution of polycarbonate is supplied into the apparatus under such conditions by a method such as spraying or dropping, the polycarbonate solution will come into contact with the polycarbonate particles present in the apparatus, and the so-called organic solvent will Some particles emit and form one after another on the upper surface of the flowing polycarbonate 7, or separate from the surface to form new granules.

The method described above may be carried out in batches, but continuous operation is more economical. In continuous operation, the amount of polycarbonate solution supplied is sufficient to match the amount of polycarbonate granules taken out, so that polycarbonate granules of uniform particle size within a certain particle size range are always present in the apparatus.

The temperature in the evaporator is set higher than the boiling point of the solvent used. For example, if the solvent is methylene chloride, 50 to 20
It may be operated at 0'C1, preferably 100 to 150'C.

Since the distilled solvent does not contain other poor solvents or water, it can be directly condensed in a cooler and recycled directly to the previous process.

To take out the polycarbonate granules, methods such as installing an overflow pipe at an appropriate position in the container and extracting the polycarbonate granules from it, or installing a switch such as a rotary valve at the bottom of the container and extracting the polycarbonate granules from there are adopted. It is better to do so.

The polycarbonate granules extracted in this way have a large bulk specific gravity of 0.5 to 0.6, and the particle sizes are uniform, so it is clear that this is convenient for workability in each subsequent process. It is.

As an industrial process that satisfies the present invention, the one shown in Figure 1 can be considered. That is, an organic solvent solution in which polycarbonate is dissolved is supplied from a storage tank 1 to a fluidized bed type evaporator 3 by a supply pump 2. Solid polycarbonate is charged into the evaporator 3 in advance. The hot air used for evaporating the organic solvent is transferred from the blower 9 to the heater 8.
The air is heated to a predetermined temperature through the air and blown into the evaporator.

The blown hot air passes through the perforated plate of the evaporator, and is discharged from the cyclone 4 through the cooler 6, accompanied by the evaporated organic solvent, to the waste gas treatment process. At this time, if polycarbonate powder is entrained, it is collected by the cyclone 4 and recovered.

The entrained organic solvent is condensed by a cooler 6 and collected into a receiver 7. The polycarbonate particles isolated from the organic solvent are discharged from the sequential evaporator 3, sieved by the sieve 5, and supplied to the next step.

A portion is recycled to the evaporator 3. Here, the evaporator 3 may be selected from those commonly used for drying and mixing powder and granular materials as described above.

[Example] The method of the present invention will be explained in more detail with reference to Examples below.

Example 1 This example was carried out using the apparatus shown in Figure 2.

Evaporator 2 in Figure-2 has an inner diameter of 10 cll+ and a height of 20 ci.
A stirring blade was installed in the container. In the evaporator, 50 g of grained polycarbonate particles (0.4-0.8 mm) are added.
It was then heated to 150°C using heating bath 3.

800 g of polycarbonate methylene chloride solution (polycarbonate content: 18% by weight) at 10 g/wi
was added dropwise to the evaporator at a flow rate of n. Add nitrogen gas to the evaporator
Supply at a flow rate of 1/win, and the rotation speed of the stirring blade is 600.
rpm. The evaporated methylene chloride was condensed in a cooler 4 and collected in a receiver 5.

As a result of analyzing the polycarbonate thus obtained, the content of methylene chloride was 1.0% by weight, and the moisture content was 0%.
The bulk specific gravity was 0.6 and the particle size was 1 to 3 am.

Further, there was no adhesion to the inner wall of the evaporator or the stirring blade.

Example 2 Fluidized bed type evaporator (inner diameter: 10CI11, total height;
It is a cylindrical type with a perforated plate with a porosity of 4% in the center of the 50C11, and the inert gas is supplied from the bottom).
) was added, and nitrogen gas was blown at 501/+*in at 120°C to keep the polycarbonate particles constantly in a fluid state.

Where this polycarbonate granule is flowing,
The same polycarbonate solution as in Example 1 was supplied from the top of the evaporator at a flow rate of 15 g/win, the organic solvent was evaporated, and the polycarbonate granules were taken out. As a result of analyzing the obtained polycarbonate granules, it was found that the content was 1.0% methylene chloride, 0% water, bulk specific gravity was 0.52, and particle size was 1.
．． 0-4°0II11 was 90% or more.

〔Effect of the invention〕

As is clear from the above examples, when the method of the present invention is applied to isolate polycarbonate from a solution of polycarbonate in an organic solvent, the method of the present invention has the following advantages over the conventional method. .

(1) The present invention does not require the use of special equipment (such as a normal fluidized bed, a fluidized bed with stirring blades, or a normal F
Any device that can fluidize the polycarbonate powder may be used, such as a cylindrical vertical pot with R stirring blades, and the polycarbonate can be taken out with a simple operation.

(2) The extracted polycarbonate is a dry product containing no organic solvent or water.

(3) The bulk specific gravity of the extracted polycarbonate is 0.5
It has a large diameter of 6 to 0.60, and is excellent in terms of storage and transportability.

(4) Since the polycarbonate particles taken out have a uniform particle size, they are easy to handle in subsequent steps.

(6) Since the solvent is directly distilled without using other poor solvents, the solvent can be easily recovered and recovered as quickly as possible.

[Brief explanation of the drawing]

Figures 1 through 2 are generally concave illustrating apparatus suitable for carrying out the invention. In the figure, 1 is a polycarbonate solution storage tank, 2 is a supply pump,
3 is a fluidized bed type evaporator, 4 is a cyclone, 5 is a sieve, 6 is a cooler, 7 is a solvent receiver, 8 is a heater, 9 is a blower, 110 is a perforated plate, 11 is an overflow pipe, I2 I3 is a polycarbonate solution powder atomizer, and I3 is a stirring blade. FIG. 2 is a schematic diagram of the apparatus used in Example I of the present invention. In the figure, 1 is a polycarbonate solution storage tank, 2 is an evaporator with stirring blades, 3 is a heating bath, 4 is a cooler, 5 is a solvent receiver, and 6
7 is a stirring blade, 7 is a polycarbonate solution dripping port, and 8 is a nitrogen supply port. Patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. In a method for producing polycarbonate granules from a polycarbonate solution in an organic solvent, a polycarbonate solution in an organic solvent is heated in an atmosphere substantially free of moisture.
A method for producing polycarbonate granules, which comprises feeding polycarbonate granules flowing at a temperature higher than the boiling point of the organic solvent to evaporate the organic solvent.