JPS60184814A - Manufacture of polycarbonate resin molding material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polycarbonate resin molding material having excellent optical properties such as transparency, and a method for producing a transparent optical polycarbonate resin molded article using the same.

For optical applications such as optical recording discs, video discs, and compact discs, transparency, moldability (including transferability), low birefringence, mold releasability, moisture resistance (especially warping due to moisture absorption), foreign matter contamination, etc. In this respect, much higher performance than conventional molding materials is required.

Polycarbonate resin is transparent, has excellent dimensional stability, and has little warping due to moisture absorption, so it is the most suitable material for compact discs, etc., but polycarbonate!・As the resin has a high melt viscosity, under normal molding conditions,
There are disadvantages such as not being able to obtain a thin disc-shaped molded product, or even if it is obtained, the birefringence of the molded product becomes large.

In order to reduce the melt viscosity of the resin, it is possible to mold the resin at a temperature higher than the usual molding temperature of 270-300°C, for example 330-380°C, but at such high temperatures, the Phenomena are observed in which the molded product is colored yellow to yellowish brown due to thermal decomposition, etc., and the molded product is dotted with brown to blackish brown dust-like substances that are insoluble in methylene chloride (a good solvent for polycarbonate resin).

Contamination of foreign substances in materials such as optical parts is an extremely serious problem in terms of performance. Contamination of foreign matter from the outside can be easily resolved by making the manufacturing, storage, and other environments dust-free. There is no other way than to prevent deterioration, and this was a fatal problem.

The inventors have made a 380° understanding of the cause of the above drawbacks.
An attempt was made to reproduce this by a melting test using a test tube under a stream of C1 nitrogen. As a result, although yellow to yellowish brown coloring of the resin was observed in glass test tubes, it was found that there was a brown to blackish brown dust-like substance in the resin that was insoluble in methylene chloride (polycarbonate-1, a good solvent for resin). No formation was observed, but it was observed when a small piece of 200 mesh wire mesh made of SO53i6, which is often used in extruders, was placed in a test tube. Furthermore, when a small piece of wire mesh was placed in a test tube, the size and amount of dust-like substances produced were approximately the same regardless of the hue of the resin used in the test. Furthermore, in the glass test tube test described above, when a small amount (about 1%) of oxygen was mixed into nitrogen, the coloring phenomenon was significantly accelerated.

From the above test results, the present inventors found that the high-temperature deterioration of polycarbonate resin is caused by: (1) deterioration that appears under anoxic conditions as a coloring phenomenon due to high temperatures, (2) significant acceleration of the coloring phenomenon by oxygen, and (2) It is assumed that there are three types of deterioration: one is the formation of brown to blackish brown dust-like substances insoluble in methylene chloride due to some interaction with the metal, that is, the metal surface inside the molding machine.

The inventors of the present invention have conducted intensive studies from various aspects to resolve the above-mentioned drawbacks, particularly the generation of dust-like substances insoluble in methylene chloride. As a result, the inventors have found that, in melting treatment in a nitrogen stream, even in the presence of small pieces of wire mesh, the resin The present invention was achieved by discovering a method for producing pellets that produces almost no trash-like substances insoluble in methylene chloride, although they are colored.

That is, the present invention provides a method for producing pellets by extruding polycarbonate resin powder using a screw extruder equipped with a hent, in which the polycarbonate resin powder is pre-impregnated with 0.1 to 5% by weight of water. ,
Or, in the hopper of the extruder, 0.0% of the weight of the extruded resin.
A method for producing polycarbonate 13] fat molding abrasive characterized by melt extruding while supplying water in an amount of 1 to 5% by weight, and in a preferred embodiment, the water has an electrical conductivity of 10 μS, 'cm or less, particularly preferably 1 μS/cm or less, is used. It also provides a method for producing a transparent optical polycarbonate resin molded product, which comprises drying the pellets obtained by the above method and then charging the pellets into a hopper supplying dry nitrogen to a molding machine for molding. It is. The present invention will be explained below.

The polycarbonate resin powder of the present invention may be a normal one, but when used as an optical material, it is preferable to use a synthetic raw material for polycarbonate resin that has been made dust-free in an environment such as production and storage. .

The water used in the present invention is pure water with an electrical conductivity of 10 μS/cm or less, particularly preferably 1 μS/am or less. Water with high conductivity often contains inorganic salts, and if such inorganic salts are mixed into the molding material, the light transmittance of the molded product will decrease due to diffuse reflection of light. Transparency is compromised.

Water can be prepared by pre-containing 0.1 to 5% water in the extruded resin powder, or adding water to the extruded resin powder in an amount of 0.1 to 5% by weight based on the extruded resin powder. Of these, the preferred method is to supply it to the screw as close to LJ as possible. If the water supplied into the popper during extrusion is not supplied smoothly to a portion of the screw, it tends to cause inconveniences such as fluctuations and steady extrusion becoming difficult.

If the amount used is less than 0.1% by weight, the stabilizing effect of the present invention will be weak, and if it exceeds 5% by weight, the resin powder will not penetrate into the screw and the amount of extruded resin will decrease, which is not preferable.

The extrusion method of the present invention is characterized by the use of water as described above, and other aspects may be the same as conventional methods. In addition, the stability of the polycarbonate resin molding material is greatly improved by the use of water, and the viscosity average molecular weight of the polycarbonate resin pellet obtained by the method of the present invention and the polycarbonate resin powder supplied to the extruder hopper are further improved. The fact that the viscosity average molecular weight of the polycarbonate resin is almost the same as that of the polycarbonate resin means that the polycarbonate resin is an ester. This is unexpected based on the common sense of those skilled in the art regarding the nature of life.

In a preferred molding method of the present invention, the dry nitrogen inserted into the hopper during molding has a purity of 99.9% or more, preferably 99.99% or more, and is preferably inserted as close to the screw as possible.

The polycarbonate resin molding material produced by the method of the present invention as described above has excellent thermal stability and does not substantially generate dust during molding, so it is equivalent to an optical additive. One thing is that there is no pay, and even for the general monthly molding fee, defects due to dust etc. are greatly reduced, so it is possible to obtain molded products with more stable physical properties. Further, according to the molding method of the present invention, high-temperature coloring is also significantly reduced, so it is suitable for molding for optical applications such as optical recording discs, video discs, and compact discs.

The present invention will be explained below with reference to Examples.

Example 1: Production of methylene chloride-insoluble substances in pellets Two types of pellets were obtained by interfacial polycondensation reaction of salty 2,2-bis(4-hydroxyphenyl)propane (hereinafter referred to as bisphenol A) and phosgene. Polycarbonate resin powder (hereinafter referred to as Δ, B) having a viscosity average molecular weight of approximately 1.8X+o' and 2.3XIO' was melt-extruded using a 40-fin φ screw extruder to form cubic pellets with a fighting angle of approximately 2.

During this extrusion, there are two types: one in which pure water with a conductivity of less than 10 μS/cm is mixed in at an amount of 2 M% based on the amount of resin (hereinafter referred to as AI, Bl), and one in which water is not used (hereinafter referred to as A2). There were a total of four types of pellets (referred to as .B2).

4g of each of the above four types of pellets were placed in a glass test tube and a glass test tube containing a 5US316 200m wire mesh, dried in a hot air circulation dryer at 120°C for 6 hours, and then dried at 120°C for 6 hours. The inside of the test tube was replaced with nitrogen by blowing dry nitrogen into the test tube for 1 hour at ℃, and immediately placed in an electric furnace maintained at 380℃ into which dry nitrogen was blown, and after being kept for 1 hour, it was cooled to room temperature. The test tube was destroyed, the resin inside was taken out, and dissolved in 25 ml of methylene chloride without stirring or other operations to obtain a resin liquid.

The entire resin solution was transferred to a petri dish with a flat bottom, and the size and number of methylene chloride-insoluble dust-like substances in each sample were visually measured.

In addition, the resin liquid was passed through a glass filter and placed in a colorimeter tube with a diameter of 10 fins, and the color of the resin liquid (APIIA) was measured by visually comparing it with the color of a platinum cobalt chromaticity standard solution of the same liquid height. . After that, the resin liquid was diluted 5 times with methylene chloride, and
It was filtered with a micron membrane filter, and the size and number of minute dust-like substances were measured using a microscope.

The results are shown in Table 1.

Example 2 In Example 1, water was not mixed into the resin powder in advance, a conduit was inserted into the hopper mouth of the screw extruder as close to the screw as possible, and the conductivity was measured using a Blunger Quibb chemical metering pump. The procedure was the same except that pure water smaller than 1071 S/am was injected at a concentration of 2% by weight based on the amount of resin extruded to obtain pellets. 5 in a glass test tube
Although the IIS 316i200 mesh wire mesh was used, almost no methylene chloride-insoluble dust-like substances were observed as in Example-1.゛Example-3 In Example-1, the pellets obtained using 2% by weight of water were placed in a hopper of a molding machine that was supplying dry nitrogen at a rate of 112/min to a part of the hopper as close to the screw as possible. injection molded at a resin temperature of 360°C to a thickness of 3II.
A disc-shaped molded product with straight f & 10 cm was obtained in step a.

A small piece of 4 g was cut out from this molded product, and its pH was measured in the same manner as in Example-1 and found to be 60. Incidentally, when molding was performed without supplying dry nitrogen, the 8-day I8 was 80.

Furthermore, in any case, no methylene chloride-insoluble substances were observed by visual observation.

Table 1

Claims (1)

[Claims] 1. A method for producing pellets by melt-extruding polycarbonate resin powder using a vented screw extruder, in which the polycarbonate resin powder contains 0.1
-5% by weight of water is added to the extruder, or by melt extrusion while supplying water in an amount of 0.1 to 5% by weight of the weight of the extruded resin into the hopper of the extruder. A method for producing a polycarbonate resin molding material characterized by: 2. The manufacturing method according to claim 1, wherein pure water with an electrical conductivity of 10 μS/cm or less is used as water. 3. In a method of producing pellets by extruding polycarbonate resin powder using a vented screw extruder, the polycarbonate resin powder is preliminarily 0.1 to 5
% by weight of water, or in the hopper of the extruder, 1 to 5% by weight of O3 based on the weight of the extruded resin.
After drying the pellets obtained by supplying an amount of water such that Manufacturing method for polycarbonate resin molded products.