JPS61250025A - Production of dried polycarbonate solid particles - Google Patents

Abstract

PURPOSE:To obtain the titled solid particles suitable for optical purposes, having a small amount of occurrence and admixture of dust during filtration and drying, by filtering water slurry of polycarbonate resin solid particles and drying the particles by the use of a specific circular barrel type filtering and drying machine. CONSTITUTION:A circular barrel type filtering and drying machine which has a conical shape at the top, cylindrical shape at the barrel part, a filtering plate in the vicinity of the bottom and rotatable round a horizontal shaft is used. Firstly, the machine is made to stand still in such a way that the filtering plate is made level, water slurry of polycarbonate resin solid particles is fed from the top to the machine in an clean air atmosphere and the slurry is filtered. Then, the solid particles are dried under heating through the heat transfer surface of the filtering and drying machine while rotating the filtering and drying machine and introducing a drying medium gas. Further, the filtering and drying machine is stopped while laying the top down and the dried solid particles are transferred to a container in the clean air atmosphere.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing dry polycarbonate solid particles, and in particular, is characterized in that filtration and drying are carried out in the same processing machine. There is little generation or contamination of fine dust due to the movement of solid particles during the drying process or imbalance in heat transfer, and the drying conditions for solid particles can be easily changed. It is particularly suitable as a method for producing polycarbonate resin for optical use.

[Conventional technology and its problems]

Conventionally, the method of extracting dry solid powder used for pellet production from a polycarbonate resin solution is to filter and separate the semi-crystalline or amorphous solidified material solidified in a solidification tank, crush it, and then It depends on the method of drying. Although this method is preferable in terms of the size of the manufacturing equipment and processing efficiency, it is difficult to avoid the generation and contamination of dust 1 from piping and equipment in the process of transferring the aqueous slurry solution of the solidified material to the drying process of the pulverized particles. Due to these problems, it has sometimes been insufficient as a method for producing polycarbonate resins for applications that require higher quality, that is, less "dust", particularly for optical applications.

[Means for solving problems]

The inventors of the present invention have developed a method that substantially eliminates the generation of dust during the process from transport in piping to drying of pulverized particles. They discovered a method for filtering and separating solid particles from an aqueous slurry and drying them in the same processing machine, and completed the present invention.

That is, the present invention provides a cylindrical filter dryer that has a conical top, a cylindrical body, and a filter plate near the bottom, and is rotatable around a horizontal axis. Stand still with the machine facing down, and perform filtration by introducing an aqueous slurry of polycarbonate resin solid particles from the top in a clean air atmosphere. Then, while rotating the filtration dryer and introducing a drying medium gas, the filtration drying process is carried out. Dry polycarbonate solid particles characterized in that the solid particles are heated and dried through the heat transfer surface of the machine, and then the filter dryer is stopped with the top down and the dry solid particles are taken out into a container in a clean air atmosphere. In a preferred embodiment, 90 wt% or more of the solid particles in the aqueous slurry of polycarbonate resin solid particles are spherical particles, and the average particle diameter is 0.5 to 2 sm. is used.

The configuration of the present invention will be explained below.

The aqueous slurry of polycarbonate resin solid particles of the present invention is a dihydric phenol compound (
A solution of a homo- or copolymer of an aromatic polycarbonate resin made by reacting BP (hereinafter abbreviated as BP) as a main component with phosgene using a small amount of a molecular weight regulator and optionally a branching agent, for example, n
- A solidification solvent such as hexane, n-hebutane, cyclohexane, toluene, etc. is added and mixed, and then the mixture is added to hot water under heating while the polymerization solvent and solidification solvent are distilled off. It is a water slurry liquid.

Preferred BPs of the present invention are of the following general formula (11
It is a compound represented by the general formula (l): (R in the formula is a divalent aliphatic, alicyclic, or phenyl-substituted alkyl group having 1 to 15 carbon atoms, or -0-, -
S-, -5o-', -3O2-, -Co-.

X is an alkyl group, an aryl group, or a halogen atom, and p
+Q is an integer from O to 2. ) Specifically, bis(4-
hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)sulfide, bis(
4-hydroxyphenyl)ketone, 1,1-bis(4-
hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis-(4-hydroxyphenyl)cyclohexane, 2,2-bis (4-hydroxy-3,5-dibromophenyl)propane, 2.2
-bis(4-hydroxy-3,5-dichlorophenyl)
Propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-
3-chlorophenyl)propane, 2.2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2.
2-bis(4-hydroxy-3-methylphenyl)propane, 1.1-bis(4-hydroxyphenyl)-1-
Examples include phenylethane and bis(4-hydroxyphenyl)diphenylmethane.

As a branching agent, phloroglycin, 2,6-dimethyl-2.4.6-tri(4-hydroxyphenyl)
Hebutene-3,4,6-dimethyl-2.4.6-)
(4-hydroxyphenyl)hebutene-2,1,3,5
-)li(2-hydroxyphenyl)penzole, 1.
1.1-)su(4-hydroxyphenyl)ethane, 2
．． 6-bis(2-hydroxy-5-methylbenzyl)-
4-methylfuenol, α, α1. α”-tri (4
-hydroxyphenyl)-1,3,5-)polyhydroxy compounds exemplified by lyisopropylbenzene,
and 3,3-bis(4-hydroxyaryl)oxindole (=isatin bisphenol), 5-chloroisatin bisphenol, 5,7-cycloisatin bisphenol, 5-bromi-isatin bisphenol, etc. The exemplified branching agent is usually 0.02 to 3 mol %, preferably 0.1 to 1. -0 mol% range is used.

In addition, monovalent aromatic hydroxy compounds as molecular weight regulators or terminal stoppers include
and p-propylphenol, p-bromophenol, p-tert-butylphenol and P-long chain alkyl substituted phenol, P-long chain alkyl etherified phenol, P-hydroxyalkyl benzoate and the like are preferred.

Aromatic polycarbonate resins include, in particular, polycarbonates containing bisphenol A as a main raw material,
Preferred examples include polycarbonate copolymers obtained by combining this with bisphenol Z, branched products thereof, and those modified with long-chain alkyl terminals.

The polycarbonate resin solution produced by the above method is subjected to the usual methods such as removing the catalyst, neutralizing, washing with water, concentrating, etc., and then microfiltered to obtain a purified polycarbonate resin solution. ,
Usually, a solidifying solvent is added and mixed, and then the mixed solution is added to hot water under heating while the solvent and the solidifying solvent are distilled off, and further, at the same time, the polycarbonate solid particles of the present invention are wet-pulverized. Water slurry liquid.

Here, the shape of the polycarbonate solid particles in the aqueous slurry obtained by this method is usually semi-crystalline or amorphous, and the size is also irregular, and there are cases where it is unsuitable for filtration or drying. be. In such a case, prior to the filtration and drying of the present invention, it is preferable to pulverize the slurry liquid using a wet pulverizer to make the particle morphology uniform.Particularly preferably, during the above-mentioned solidification, the solidified liquid is pulverized using a wet pulverizer. In particular, 90% or more of the solid content after drying, obtained by a method of circulating and pulverizing, is spherical polycarbonate solid particles, and the average diameter of the core spheres is 0.5 to 2. It is suitably used as the polycarbonate solid particle water slurry liquid of the present invention.

In a clean air atmosphere, the above water slurry of polycarbonate solid particles is introduced from the top into a stationary filtration dryer with the bottom facing down so that the filter plate is horizontal, and filtered. The solid particles are heated and dried through the heat transfer surface of the filter dryer while rotating and introducing a drying medium gas, and then the filter dryer is stopped with the top down and the solid particles are dried in a clean air atmosphere. Filtration separation and drying are performed by removing the particles into a container.

As the filter dryer used in the present invention, any device can be used as long as it meets the above conditions, but for example, a filter dryer manufactured by Tsukishima Kikai ■ is exemplified as a suitable model, and furthermore, A closed type filter dryer manufactured by Kuri Kagakuso Wl@ is also exemplified.

Examples of the drying medium gas include clean air obtained by filtering, or air obtained by adding an inert gas such as nitrogen to avoid the explosion limit due to organic solvent vapor generated in the drying atmosphere. , introduced under normal pressure to pressurization at a temperature of 120 to 150°C, and discharged. When the exhaust gas contains a large amount of organic solvent components or when recovery is required, treatment by catalytic catalytic combustion, cooling, adsorption, or other means is naturally carried out as appropriate.

The temperature of the heat transfer surface of the filtration dryer is adjusted appropriately to be in the range of 80 to 160°C, especially 100 to 150°C, and the heating method is steam heating or oil circulation heating to avoid local heating. A method using a heat medium such as is preferred.

In addition, the drying time varies depending on the size, density, solidification method, etc. of the solid particles in the water slurry used, and is selected as appropriate, but is usually in the range of 3 to 12 hours. selected from.

Incidentally, the temperature and degree of drying during drying in the filtration dryer are naturally selected and used appropriately.

〔Example〕

Hereinafter, this will be explained in detail using examples and the like.

Example-1 Using 2.2-bis(4-hydroxyphenyl)propane (hereinafter referred to as BPA) as BP, converting it to 2.6-dimethyl-2.4.6-tri(4-hydroxyphenyl) as a branching agent. Terminated p-tert-butylphenol (hereinafter referred to as
Spherical polycarbonate resin solid particles obtained by wet-pulverizing a purified polycarbonate resin solution with a viscosity average molecular weight of 115.000 (referred to as PTBP) at the same time as solidification.
Using a 0% by weight water slurry, the water slurry was introduced into a filtration dryer (trade name: filtration dryer, manufactured by Tsukishima Kikai ■) installed in a clean room, and after filtration, the filtration dryer was While rotating, steam was passed through the jacket side at a rate of about 0.5 kg/cdG, and dust-removed nitrogen gas was passed through the main body side as a carrier gas under atmospheric pressure, while drying was carried out for about 8 hours.

Table 1 shows the measurement results of the number of particles in the solidified material, the amount of bead-like particles in the solid particles, their average diameter, etc.

Example 2 The same procedure as in Example 1 was carried out except that an aqueous slurry of polycarbonate resin containing lauryl p-hydroxybenzoate was used instead of PTBP.

Table 1 shows the measurement results of the number of particles, the amount of bead-like particles in the solid particles, their average diameter, etc. of this solidified material.

Comparative Example 1 In Example 1, the aqueous slurry of polycarbonate resin was separated into solid and liquid using a centrifuge, and then dried for about 3 hours using a flash dryer and a paddle dryer. Note that the atmospheric conditions during transfer, drying, etc. were the same as in Example-1.

The measurement results of this solidified product are shown in Table 1.

Table 1 [Operations and Effects of the Invention] As is clear from the detailed description and examples above, the polycarbonate resin produced by the filtration and drying method of the present invention has extremely low generation and contamination of dust during filtration and drying. It can be seen that the solidified material is extremely clean as in the water slurry.

Claims (1)

[Claims] 1. A cylindrical filtration dryer having a conical top, a cylindrical body and a filter plate near the bottom, and rotatable around a horizontal axis,
The filter plate stands still with its bottom facing down horizontally, and a water slurry of polycarbonate resin solid particles is introduced from the top in a clean air atmosphere to perform filtration, and then the drying medium is removed while rotating the filter dryer. heating and drying the solid particles through the heat transfer surface of the filter dryer while introducing gas, and then stopping the filter dryer with its top down and removing the dry solid particles into a container in a clean air atmosphere; A method for producing dry polycarbonate solid particles characterized by: 2. The manufacturing method according to claim 1, wherein 90 wt % or more of the polycarbonate resin solid particles in the aqueous slurry are spherical particles and have an average particle diameter of 0.5 to 2 mm.