JPS5912962A - Heat stabilized polycarbonate resin composition - Google Patents

Abstract

PURPOSE:To suppress the foaming of a polycarbonate resin, clouding with steam, and discoloration and deterioration by high-temperature molding, by adding phosphorous acid, a specific phosphite and water to a polycarbonate resin. CONSTITUTION:Polycarbonate resin is compounded with 2-20ppm (by weight) of phosphorous acid, 50-300ppm of tri-(2,6-di-t-butylphenyl) phosphite and 0.1- 0.5wt% of water. The addition is carried out preferably, in view of dispersibility, by mixing dried resin powder with an aqueous solution of phosphorous acid together with the phosphite.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-stabilized polycarbonate resin composition in which color deterioration during molding at high temperatures is extremely effectively suppressed. ppm of 111-phosphoric acid and 5 U ~
5 U O ppm of 2, , 6-T
-butylphene I) phosphite and u. i~0.
Concerning a heat-stabilized polycarbonate resin composition that is made by adding 5% water and is highly effective in suppressing discoloration caused by high-temperature acids, molded articles obtained using the composition have good hot water resistance. Excellent and no decrease in mechanical strength.

Aromatic polycarbonate resin is transparent and has excellent heat resistance and impact resistance, so it is a useful resin that is widely used in a variety of applications.However, due to its high viscosity when melted,
It is difficult to mold large molded products or thin molded products.For this reason, aromatic polycarbonate resins have recently been molded at higher temperatures of 500°C or higher. In molding at high temperatures, particularly in continuous molding over long periods of time, aromatic polycarbonate resins often suffer discoloration and deterioration due to thermal decomposition in the retention area inside the cylinder of the molding machine, which poses a practical problem. Thermal decomposition in the retention zone is not simply caused by heat, but is thought to be promoted by some kind of action by the metal that the molten resin comes into contact with. This causes a significant decrease in component value.

Various methods have been proposed to prevent such color deterioration during molding of polycarbonate resin, for example,
A phosphorus compound such as phosphorous acid or triphenyl phosphite disclosed in Japanese Patent Publication No. 56-5596 is often used as a stabilizer. However, although phosphorous acid or organic phosphite esters are certainly effective in preventing color deterioration of polycarbonate resin, in the case of phosphorous acid, at least It is necessary to add 200 ppm or more of fiL each, which may cause defects such as air bubbles occurring inside the molded product during molding, or the molded product becoming extremely cloudy when exposed to water vapor, and a decrease in molecular weight and mechanical strength. It's difficult to avoid. In Special Publication No. 56-25950,
Attempts have been proposed to overcome the drawbacks associated with the use of phosphorous acid or organic phosphorous esters by blending them with alkali metal halides. However, when a considerable amount of an inorganic salt such as an alkali metal logenide is mixed into a polycarbonate resin, the transparency of the polycarbonate resin is impaired, and its commercial value for optical applications is significantly reduced. .

The inventors of the present invention have conducted extensive research to solve the drawbacks of incorporating such phosphorous acid or organic phosphite esters, and have found that a very small amount of phosphorous acid and a small amount of phosphorous acid esters are mixed with a very small amount of phosphorous acid. It has been found that by using a combination of J-(2,6-butylphenyl)phosphite and water, an unexpectedly excellent stabilizing effect is exhibited due to a mutual effect. The permeability and mechanical strength of the molded product molded from the heat-stabilized polycarbonate resin composition obtained here are not impaired at all, and no air bubbles are generated in the molded product, and furthermore,
For example, even when exposed to water vapor at 120° C. for a long time, the molded product showed no clouding at all, indicating that it had an extremely excellent thermal stabilizing effect.

The polycarbonate resin referred to in the present invention has the general formula (1)
Refers to aromatic polycarbonate homopolymers and copolymers obtained by reacting a dihydric phenol compound represented by the formula with a carbonate precursor, such as phosgene.

General formula (wherein R1, R2, 5 and R4 are hydrogen atoms,
They are lower alkyl groups or...rogen atoms, all of which may be the same or different, and Y represents alkylene, ether (-0-), thioether (-S-), or sulfone ( -5 2) The meaning of the bridge part is 1. ) Specifically, this divalent phenol compound includes 2
．． 2-bis(4-/-idroxyphenyl)bripan,
2,2-bis(4-/1 idroxyphenyl)methane,
4.4'-dihydroquine diphenylthioether sidiphenyls I lehon, 4.4'-dihydroxydiphenyl ether sifrim-4-hydro p-xyphenyl)propane, 2.
2-bis(5,5-dichloro-4-hydroxyphenyl)butane, 2,2-bis(5,5-dimethyl-4-
Hydroxyphenyl)propane and the like can be mentioned.

As mentioned above, the heat-stabilized polycarbonate resin composition of the present invention is obtained by blending three specific compounds in a specified range with a polycarbonate resin, and the combination of these two and its The formulation amount is extremely specific; for example, tri(di-butylphenyl) phosphite is a compound that belongs to the group of organic phosphites, but it is a compound that belongs to the same group. When triphenyl phosphite is used, the same effect as in the composition of the present invention cannot be obtained.

The amount of each compound added to the polycarbonate resin is 2 to 20 ppm for phosphorous acid, and 50 to 500 ppm for )2 (di-t-butyl'phenyl) phosphite.
1) 9m% and water is determined in the range of 0.1 to 0.5% (all based on weight), but if the amount below the lower limit is used, the desired stabilizing effect will not be achieved, and if the amount is above the upper limit For phosphorous acid and phosphite, the clouding phenomenon due to contact with superheated steam is
This tendency tends to be larger than in the case of polycarbonate resin without the addition of a stabilizer, which is not desirable in practice, and water causes poor penetration of the resin into the screw during melt extrusion, causing a decrease in production. The stabilizers used in combination in the present invention and the prescribed amounts will be specifically explained later in Examples.

There are no particular limitations on the method for preparing the polycarbonate resin composition of the present invention. For example, dry polycarbonate resin powder is mixed with an aqueous solution prepared by dissolving a predetermined amount of phosphorous acid in a predetermined amount of water, and a predetermined amount of phosphorous acid. The stabilizer may be mixed with an ester, and this method is a more preferable embodiment in terms of the dispersibility of the stabilizer.

The polycarbonate resin composition of the present invention may optionally contain various additives such as fillers, dyes and pigments, fiber reinforcing materials, antioxidants, ultraviolet absorbers, and mold release agents.

The present invention will be specifically explained below with reference to Examples and Comparative Examples. As can be seen from the results in Table 1 below, the tri(di-t-butylphenyl) phosphite used in the present invention is Unlike the case of phenyl phosphite, it has a poor stabilizing effect when used alone, but it is found to have extremely high resistance to the hot water phenomenon caused by exposure to water vapor and the generation of bubbles in molded products during molding. This is thought to be due to the fact that this phosphorous ester is resistant to hydrolysis and heat due to its structure. The present invention combines tri(di-t-butyphrephenyl) phosphite, which has high resistance to hydrolysis and heat but has a poor stabilizing effect on polycarbonate resins, and extremely ilk, i.e., sufficient By using phosphorous acid and water in an amount that is insufficient to exert a stabilizing effect, but does not cause clouding when exposed to water vapor, a balance in performance can be achieved and an extremely We have discovered a stabilizer that exhibits a high stabilizing effect.

Example 1 and Comparative Example 1-7 Polycarbonate resin obtained from 2.2-bis(4-hydroxyphenyl)furopane and phosgene by interfacial polycondensation method 1 [manufactured by Mitsubishi Gas Chemical Company, trade name: Niepiron 520]
00] powder, an aqueous solution in which phosphorous acid in an amount of 10 ppm based on the weight of the resin was dissolved in water in an amount equivalent to 0.596 weight based on the weight of the resin, and Tri(di-t-butylphenyl)phosphite in an amount of 50 oppm was added and thoroughly mixed using a mixer.The obtained powder was melt extruded using a 4016 screw extruder to form cubic pellets of 2W square.

Put this pellet) 4f in a test tube, dry it for 1 hour in an atmosphere of 120℃ without introducing nitrogen, and then dry it for 1 hour at a temperature of 540℃ in a nitrogen stream! A melting test was conducted. Separately, a small piece of 200 mesh wire mesh made of 5US516 was placed in a test tube to ensure contact with metal surfaces in the molding machine and in contact with the resin melt. A melting test was conducted. After completing the melting test,
The resin in the test tube was dissolved in 25 cc of methylene chloride, and the hue of the solution was visually compared with the color of a platinum-cobalt chromaticity standard solution, and measured as A P I (A value).

Next, using the above pellet, injection molding was performed to a thickness of 5
A two-open plate-shaped molded product was obtained. This was heated to steam at 120° C. for 100 hours in an autoclave. After the test, the acidity was measured using a haze meter.

The results of these measurements are shown in Table 1.

Furthermore, when the viscosity average molecular weight of the sample after the above water vapor treatment test was measured, the viscosity average molecular weight of the sample to which no stabilizer was added (blank) was 22 x 104 before the test and 2. lX1
The stabilizer of the present invention was added to 2.0' before the test. ．． 2X10. ', after the test 2. lX10'
Met. By the way, triphenylposphite 500
When ppm was added (Comparative Example 4), a similar test was conducted and the viscosity average molecular weight before the test was 2.2.
It was found that the value was 1.5X104 after the test.

For reference, a blank test (Comparative Example 1), phosphorous acid alone (Comparative Example 2), phosphorous ester alone (Comparative Example 5)
-5), water alone (Comparative Example 6) and a mixture of phosphorous acid and phosphite ester (Comparative Example 7) were blended, treated in the same manner as above, and measured. The results are also listed in Table 1.

As is clear from Table 1, Comparative Example 2. In 5.5 and 6, significant color deterioration equivalent to the plaque test was observed, indicating that the stabilizing effect was not achieved in either case.
It can be seen that in Comparative Example 4, although the deterioration of the adhesive 6 was suppressed, the clouding caused by the steam treatment was significant. On the other hand, the stabilizer system of the present invention shows the same effect as triphenyl phosphite in terms of color deterioration at ℃, but it can be said to be a surprising result that the hot water phenomenon caused by steam treatment is significantly prevented. .

In Table 1, 15 molded products with a resin temperature of 5 degrees were obtained from the above pellets, and the number of molded products in which at least one air bubble was formed is shown in the numerator to calculate the bubble generation rate. The results are also listed.

Compared to Comparative Examples 5 and 4, no bubbles were observed in the composition of the present invention.

・　□　　　　　　　　.

Table 1 σ) Note: -1+A is tri(2,6-di-t-butylphenyl) phosphite B is triphenyl phosphite *-2: 120'
After being exposed to the water vapor of C for 1 hour, the total transmittance Tt (= T2/TI) was determined using a haze meter, and the larger the value of 7+i% degrees, the greater the white turbidity. (Here, T1 is the amount of incident light, 1゛2 is the total amount of transmitted light, T3 is the amount of light scattered by the device, and T4 is
represents the amount of light scattered by the device and test t1. ) Example 2-4 The results of measuring various properties are also listed in Table 1 in the same manner as in Example 1 except that three types of stabilizers were used in the proportions shown in Table 1.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative Kazuyoshi Nagano

Claims (1)

[Claims] Polycarbonate resin with 2-20 ppm (wt) phosphorous acid, 50-500 ppm (wt) Tory C'2
．． 6-di-t-butylphenyrite and 0.1-0
．． A heat-stabilized polycarbonate resin composition that is made by adding 5% (by weight) of water and is highly resistant to color deterioration.