JPS62169605A - Granulation of polycarbonate - Google Patents

Abstract

PURPOSE:To facilitate handling, drying, transportation and the like and simplify the process of granulation by a method wherein undried and solid polycarbonate is supplied to an extruder provided externally with a die having a multitude of fine holes and is extruded under a temperature lower than the melting point thereof, thereafter, is cut into a desired length. CONSTITUTION:Aromatic polycarbonate, employed in this method, is obtained by liquid solution method wherein the dihydric phenol is polymerized by reacting with phosgene or dichloroformate by a normal method under the existence of methylene chloride. The undried and solid polycarbonate is supplied to an extruder provided externally with a die having a multitude of fine holes to extrude it under a temperature lower than the melting point thereof, thereafter, is cut into a desired length to obtain granular products. When the internal temperature of the extruder becomes higher than the melting point of the polycarbonate in this case, the polycarbonate comes into liquidous state and drips down from the die and the rolling of the undried and solid polycarbonate becomes unstable. This solid carbonate is granulated into grains with a high bulk density and equal size, therefore, handling may be facilitated thereafter, process may be simplified and the device therefor may be miniaturized and simplified.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention improves the appearance, shape retention, and fluidity of undried solid polycarbonate separated by concentrating a polycarbonate solution or contacting and gelating it with a non-solvent. .

The present invention relates to a method for producing granules that are easy to handle, have a large bulk density, and have a sharp particle size distribution.

(Prior Art) Various methods have been proposed for isolating polycarbonate obtained by a solution method. That is, a method of making flakes or granules by contacting with hot water or steam (for example,
6-11231. 40-3533. 40-9843
, 46-37424. Japanese Patent Publication No. 48-43752. Same 5
4-122393), a method of gelling and pulverizing by concentration or cooling (for example, Japanese Patent Publication No. 36-21033).
38-22497゜40-12379. 45-9
875. (Japanese Patent Publication No. 47-41421), gelling, pulverization, or fine granulation using a non-solvent or poor solvent (for example, Japanese Patent Publications No. 36-22447, No. 3B-22448, No. 37)
-7000. 42-1435. 42-7703. No. 46-31468, No. 55-21773), a method of heating and removing the solvent to form powder or pellets (for example, Japanese Patent Publications No. 3B-22890, No. 38-14499, No. 38 of the same
-24724. 48-22840), other methods (for example, Japanese Patent Publication No. 54-43040, Japanese Patent Publication No. 55-129)
Publication No. 8> etc. are known. However, in most of these methods, the resulting flakes or granules are dried to remove solvent, and then made into pellets by melt extrusion. It requires a lot of equipment and a lot of energy, and transportation is often troublesome.

Furthermore, the method of heating and desolventizing the solution to form powder or pellets requires large equipment and a lot of energy, and furthermore, the equipment is susceptible to corrosion.

(Objective of the Invention) The object of the present invention is to immediately granulate undried flaky, granular, or lumpy polycarbonate separated from a methylene chloride solution of aromatic polycarbonate for subsequent handling.

The object of the present invention is to provide a method for facilitating drying, transportation, etc. and simplifying the process.

(Structure of the Invention) The present invention involves supplying undried solid polycarbonate separated from a methylene chloride solution of aromatic polycarbonate obtained by a solution method to an extruder equipped with an external die having a large number of pores. This granulation method is characterized by extruding the material at a temperature below its melting temperature and then cutting it into desired lengths and granulating it.

The aromatic polycarbonate used in the present invention is
It is obtained by a solution method in which dihydric phenols are reacted with phosgene or dichloroformate in the presence of methylene chloride and polymerized by a conventional method.

The dihydric phenols used here include hydroquinone, 4.4-dihydroxydiphenyl, his(4-hydroxyphenyl)methane, 1.1-bis(4-hydroxyphenyl)ethane, 2.2-bis(4- hydroxyphenyl)propane (hereinafter referred to as bisphenol A), 2
．． 2-bis(4-hydroxyphenyl)butane, 1.1
-bis(4-hydroxyphenyl)cyclohexane, 1
-phenyl-1,1-bis(4-hydroxyphenyl)
Ethane.

Bis(4-hydroxyphenyl)ether, bis(4-
hydroxyphenyl)ketone, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)
Examples include sulfone and lower alkyl or halogen substituted products thereof.

The aromatic polycarbonate obtained from these dihydric phenols may be a homopolymer or copolymer, or a mixture of two or more types of polycarbonates.

In order to obtain undried solid polycarbonate from a methylene chloride solution of these aromatic polycarbonates, various methods as described above can be used, but the solid polycarbonate is in the form of flakes.

It may be in any shape, such as powder or small lumps, and may have either hardness or softness, but (1) it is not sticky at room temperature, and (2) it cannot be compressed at its melting temperature. It is desirable that the material can be molded by using the same method, and for that purpose, it is necessary to contain some good and/or poor solvents.

Good solvents and poor solvents differ depending on the type of aromatic polycarbonate used, but when talking about bisphenol A polycarbonate, good solvents include: 1.
1゜2.2. -Ethane tetrachloride, methylene chloride, 1.2-
Ethylene dichloride, chloroform, 1.1.2-ethane trichloride, ethane 1.2-dichloride, thiophene, dioxane, tetrahydrofuran, and examples of poor solvents include anisole and cyclohexane.

The content of good solvent and/or poor solvent varies depending on the type of aromatic polycarbonate and the type of solvent, but when talking about the combination of bisphenol A polycarbonate and methylene chloride, the content of methylene chloride is based on the total of both. is preferably about 10 to 70% by weight, more preferably 35 to 60% by weight.

The solid polycarbonate also contains various commonly used additives, such as stabilizers, ultraviolet absorbers, and mold release agents.

It may contain a coloring agent, an antistatic agent, a flame retardant, etc.

In the method of the present invention, the undried solid polycarbonate is fed to an extruder equipped with an external die having a large number of pores, extruded at a temperature below its melting temperature, cut into desired lengths, and turned into granules. become.

At this time, if the internal temperature of the extruder exceeds the melting temperature, the polycarbonate will flow down from the die in liquid form, and the undried solid polycarbonate will become unstable. Therefore,
The extruder may be cooled without heating to maintain an internal temperature of preferably 100°C or less, more preferably 5°C or less.
It is desirable to maintain the temperature below 0°C. Also, during this extrusion, most of the non-solvent that was attached to or contained in the undried solid polycarbonate is separated on the opposite side of the die.

The obtained granules are immediately heated continuously at 160°C or less, or
Even when dried in batches, there are no problems such as agglomeration, and granules with excellent appearance, fluidity, shape retention, and handling properties, large bulk density, and uniform particle size can be obtained.

The extruder used in the present invention is a single-screw or multi-screw extruder, or a plunger extruder.

Alternatively, an extruder having a mechanism such as an injection molding machine having an inner screw is exemplified, and furthermore, in extrusion of undried solid polycarbonate, depending on the solvent concentration in the polycarbonate and conditions, the polycarbonate may be extruded due to an increase in the internal temperature of the cylinder. In order to avoid problems such as melting, it is preferable to use a cylinder with a jacket for temperature control and a screw with a groove, and a cylinder with a vent and a screw with a compression ratio can also be used.

The die can be either a pre-extrusion die that extrudes in the same direction as the extruder, or a lateral extrusion die that extrudes at right angles to or transversely to the extrusion axis. The hole structure of the pre-extrusion die preferably has a hole diameter of 0.3 to 2 mm from the viewpoint of extrusion ability and solvent removal.

Although the land length may have the same hole diameter and pass through the die, it is preferable to use two-stage communicating holes with the same hole axis and different hole diameters. In that case, from the viewpoint of the strength of the granular material, the discharge pressure, and the strength of the die, the ratio of the small diameter land length (shi) and the hole diameter (D) should be L/D = 1 to
Preferably it is 10.

The diameter of the large hole and the land length may be such that they do not interfere with extrusion.

As for the outside-crossing method of the die, either the large or small hole diameter side may be attached to the cylinder, but it is preferable to attach the small hole side to the cylinder.

In a horizontal extrusion type die, one side of the tubular die is closed, and a hole is made in the tube wall at right angles or in a direction transverse to the extrusion axis, and a torpedo-shaped object is attached to reduce the amount remaining inside the tube. Also good. Hole diameter 0°3~2mm, land length 0.5mm
~The thickness of the tube wall is preferable, but if the tube wall is thick, a two-stage communicating hole may be used as in the pre-extrusion type.

The extruded solid polycarbonate can be cut in a variety of known ways. A preferred example is a method of cutting by rotating a propeller attached so as to be parallel to the die surface. Cutting can also be done underwater. The length of the granules is adjusted by the distance between the die and the propeller.

(Effects of the Invention) According to the method of the present invention, the solid polycarbonate separated from the methylene chloride solution is in the form of particles with high density and uniform size. is easy, therefore the process can be simplified,
The device can also be made small and simple. In addition, the polycarbonate granules obtained by drying have excellent appearance, shape retention, fluidity, and handling properties, and are easy to work with and measure when blending various additives and reinforcing materials, making it easy to automate processes. Make it. Furthermore, the dried granules can be easily fed to a molding machine without forming bridging in the hopper even if used as is without being melted into pellets, and the molded product has a small thermal history, making it an excellent product. Finished in hue and quality.

(Example) The present invention will be explained using an example. In the examples, the particle size is shown as the value at the 50% point of cumulative weight on the sieve, and the particle size distribution is RO3IN-
It is shown by the value of n in the distribution formula of R^LER. Note that % indicates weight %.

Example 1 A 150 g kneader was charged with 27 ρ of hot water at about 50°C, and while steam at a pressure of 3 kmCm2 was gradually blown into the aqueous layer, 15% polycarbonate (average molecular i25,0
A methylene chloride solution of 2401 (00) was gradually added to the mixture to gel and coarsely crush the mixture in about 1 hour. The resulting gelled crushed material contained 48% polycarbonate.

The content was 36% methylene chloride and 16% water.

The extruder used was a cylinder with a jacket for temperature control, a die was installed externally, and the diameter was 40 mm, L/D -8.
There is no compression ratio and a screw with a groove depth of 6 mm is installed inside. Furthermore, the external die has a hole diameter of 1 mm on the same hole axis, 1
．． 4mm, the corresponding land length is 2mm, 13mm2
It is a front extrusion type with a plate thickness of 15 mm and has 400 stepped communication holes. An end tube for measuring the discharge pressure was installed between the gouer and the cylinder, and a cutting machine (a single-blade propeller with a length of 50 mm) was placed in front of the die with an interval of 1.5 mm. The gelatinized coarse material was supplied to an extruder and cut by an extrusion cutting machine AORPM with a screw speed of 30 rpm to obtain a granular material. Separated water to the screw gland side is approximately 45.1! .

Discharge pressure is 32k(]/Cll12, discharge amount is 5kMH
It was r.

The granules were immediately dried in a vacuum dryer at 140°C for 6 hours. There was no problem with no agglomeration phenomenon. The particle size of the dry granules is 0.7 mm, the bulk density is 0.59 or/d, and n is 3.
6. The angle of repose was 27°.

Example 2 Using the same equipment as in Example 1, screw compression ratio 1.7°, screw 80 rpm, cooling water approximately 10°C, 500.1!
The process is the same as in Example 1 except that /Hr is circulated. Separated water is 40B.

The discharge pressure was 40 kmcm2, the discharge amount was 9 ka/Hr, and there was no problem with agglomeration during drying. Particle size is 0.7
5mm, bulk density is 0.57ill/11B1! , n
is 3.8. The angle of repose was 25°.

11 Example 3 To 25 g of the 15% polycarbonate solution obtained in Example 1, add 7 acetone, O, l! Mix evenly, about 40.1! Heat and concentrate at normal pressure in a jacketed kneader to give about 2.
It was gelled and crushed in 5 hours. The crude product was immediately treated in the same manner as in Example 1 using the same equipment. The discharge pressure is 3 og/cm2,
The discharge amount was 5kMHr. Immediately remove this granular material for 14
It was dried for 6 hours in a vacuum dryer at 0°C.

There were no problems such as agglomeration phenomenon. The particle size of the dry granules was 0.73 mm, and the bulk density was o, 58 gr/d.

n is 3,7. The angle of repose was 26°.

Example 4 1.1-Bis(4-hydroxyphenyl)cyclohexane and phosgene were reacted in the presence of methylene chloride,
A 15% solution of polycarbonate with ηsp 0.43 (0.7 or /100 trdl methylene chloride, 20° C.) was obtained.

Approximately 50℃ warm water 30.1 for a 150g kneader! Then, steam at a pressure of 3 kQ/Cm2 and 220 ml of polycarbonate solution were gradually injected, and in about 1.4 hours, a rice cake-like material consisting of 39% polycarbonate, 37% methylene chloride, and 24% water was obtained. This was fed to the extruder used in Example 1 to obtain granules. Separated water to the screw gland side is approximately 40.1! The discharge pressure was 34 kg/Cm2, and the discharge amount was 5 kmHr. The granules were immediately dried under an air stream at 120° C. for 9 hours, but there were no problems such as agglomeration. The diameter of the dry granules was 0.8 mm, the bulk density was 0.57 (1! r/ml, n was 3.6, and the angle of repose was 27°.

Example 5 262-bis(4-hydroxyphenyl)propane 50
% and 50% of 2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and phosgene were reacted in a conventional manner using methylene chloride7.
731) 0.47 (0.7gr/100ma
A copolymerized polycarbonate of methylene chloride (20°C) was obtained. 13% polycarbonate solution 200.1!
was treated in the same manner as in Example 4, and in about 1.5 hours, 45% polycarbonate, 30% methylene chloride, 25% water
% was obtained. This was treated in the same manner as in Example 2 using the same equipment.

The amount of separated water was approximately 35 B, the discharge pressure was 40 kg/cm2, and the discharge amount was 9 kmHr, and there was no problem with agglomeration during drying. The particle size is 0.75111111. Bulk density is 0.5
9Or/d, rl is 3.8. The angle of repose was 26°.

Comparative Example 1 1.1-Bis(4-hydroxyphenyl)cyclohexane and phosgene were reacted using methylene chloride in a conventional manner to give 77Sl) 0.44 (0.7or/10
A 14% solution of polycarbonate in methylene chloride (20° C.) was obtained. 30. Approximately 50℃ warm water in a 150ρ kneader. I! and pressure 3kMc
m2 of water vapor and a polycarbonate solution of 200 IQ were gradually added, and in about 1.5 hours a fibril-like solid material was obtained through a cake-like material. This solid was immediately dried under a stream of air at 120° C. for 9 hours. The particle size of the dried product is 1.2 mm, the bulk density is 0.42 Or/me, and n is 2.7. The angle of repose is 3
It was 9°.

Procedural amendment March 6th, 1985

Claims (1)

[Claims] (1) Undried solid polycarbonate separated from a methylene chloride solution of aromatic polycarbonate obtained by a solution method was fed to an extruder equipped with an external die having many pores and extruded at a temperature below its melting temperature. A method for granulating polycarbonate, which is then cut into desired lengths and granulated.