JPH06306266A - Light-diffusing polycarbonate resin composition - Google Patents

Abstract

PURPOSE:To provide a polycarbonate resin composition containing a specific inorganic compound, exhibiting light-diffusibility and opaque white translucency, free from excessive depression of melt-viscosity of a polycarbonate resin used as the base resin and preventing the surface roughening caused by the secondary agglomeration of the light-diffusing agent. CONSTITUTION:A light-diffusing polycarbonate resin composition is produced by compounding 100 pts.wt. of a polycarbonate resin with 0.5-10 pts.wt. of precipitated barium sulfate having an average particle diameter of 0.1-20mum and pH of 3.0-7.5. A light-diffusing, opaque white translucent polycarbonate resin composition is produced by compounding the above light-diffusing resin composition with 0.001-0.2 pts.wt. of titanium oxide based on 100 pts.wt. of the polycarbonate resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin composition containing a specific inorganic compound and exhibiting light diffusivity and translucency of milky white.

[0002]

2. Description of the Related Art Polycarbonate resins have excellent impact resistance, heat resistance, weather resistance and the like, and are used in various applications as resins having high light transmittance. Of them
A semi-transparent material may be required for various lighting fixture covers, translucent plates that block light inside and outside the factory to take in light. As a material suitable for this kind of use, a polycarbonate composition comprising calcium carbonate and titanium oxide in combination has been proposed (Japanese Patent Publication No. 57-24816). However, since the polycarbonate composition described in JP-B-57-24816 significantly lowers the melt viscosity of the polycarbonate in the product manufacturing process, the molding conditions are not stable in extrusion molding and a good surface condition is obtained. Molded product cannot be obtained. In addition, in injection molding, since the temperature range in which molding is possible is narrow, there is a drawback that problems such as defective molding and damage to the mold are likely to occur. further,
The calcium carbonate used in the proposal had many drawbacks such as difficulty in obtaining a product having a good glossy surface condition because secondary aggregation was likely to occur.

[0003]

DISCLOSURE OF THE INVENTION The present invention has a light diffusivity that does not significantly lower the melt viscosity of a polycarbonate resin that is a base resin and that eliminates surface roughness due to secondary aggregation of a light diffusing agent. It is an object of the present invention to provide the above polycarbonate resin composition.

[0004]

As a result of intensive studies to solve such problems, an average particle diameter of 0.1 to 20 μm and a pH of 3.0 with respect to 100 parts by weight of a polycarbonate resin.
It was found that the polycarbonate resin composition to which the precipitated barium sulfate in the range of ˜7.5 is dispersedly added can exhibit an excellent light diffusivity with almost no decrease in melt viscosity.

The present invention will be specifically described below. The aromatic polycarbonate used in the present invention is a polymer obtained by a phosgene method of reacting various dihydroxydiaryl compounds with phosgene, or a transesterification method of reacting a dihydroxydiaryl compound with a carbonic acid ester such as diphenyl carbonate. As a typical example, there is a polycarbonate produced from 2,2-bis (4-hydroxyphenyl) propane 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

Examples of the dihydroxydiaryl compound include bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, and 2,2-bis (4-hydroxyphenyl) butane, in addition to bisphenol A. , 2,2-bis (4-hydroxyphenyl)
Octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl-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-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-)
Bis (hydroxyaryl) alkanes such as 3,5-dichlorophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4
Bis (hydroxyaryl) cycloalkanes such as -hydroxyphenyl) cyclohexane, 4,4'-
Dihydroxy diphenyl ether, dihydroxy diaryl ethers such as 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide Such dihydroxydiaryl sulfides, 4,4′-dihydroxydiphenyl sulfoxide, 4,4′-dihydroxy-3,3′-dimethyldiphenyl sulfoxide such as 4,4 ′
-Dihydroxy diphenyl sulfones, dihydroxy diaryl sulfones such as 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone, and the like. These may be used alone or in admixture of two or more, but in addition to these, piperazine, dipiperidyl hydroquinone, resorcin, 4,4'-dihydroxyphenyl and the like may be mixed and used.

Further, the above-mentioned dihydroxyaryl compound and a phenol compound having a valence of 3 or more as shown below may be mixed and used.

As trihydric or higher phenols, phloroglucin, 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -heptene, 4,6-dimethyl-
2,4,6-tri- (4-hydroxyphenyl) -heptane, 1,3,5-tri- (4-hydroxyphenyl)
-Benzol, 1,1,1-tri- (4-hydroxyphenyl) -ethane and 2,2-bis- [4,4-
(4,4′-dihydroxydiphenyl) -cyclohexyl] -propane and the like. The viscosity average molecular weight of polycarbonate is usually 10,000 to 100,000.
It is 0, preferably 15,000 to 35,000. In producing such a polycarbonate, a molecular weight modifier, a catalyst and the like can be used if necessary.

The precipitated barium sulfate of the present invention is obtained by a method which is generally used industrially. For example, a sodium sulfate solution is added to a barium sulfide solution obtained by reduction barite burning of barite to cause precipitation. It is desirable that the pH is in the range of 3.0 to 7.5, and more preferably 5.0 to 6.5. Also,
The average particle diameter used in the present invention is required to be in the range of 0.1 to 20 μm, and particularly preferably 1 to 15 μm. When the average particle diameter is less than 0.1 μm, effective light diffusion cannot be obtained when dispersed and added to polycarbonate. On the other hand, if the average particle size exceeds 20 μm, the impact resistance, which is a characteristic of polycarbonate, is significantly reduced. If the amount of the precipitated barium sulfate added is less than 0.5 parts by weight with respect to 100 parts by weight of the polycarbonate resin, effective light diffusivity cannot be obtained. Therefore, when you look at the object on the other side through the molded product manufactured using the resin composition, the shape of the object becomes clear,
It is not suitable as a so-called ground glass substitute application. Again 1
Even if added in an amount of more than 0 parts by weight, the total light transmittance and the light diffusion transmittance will be low, and the original purpose cannot be achieved.

The pH of the precipitated barium sulfate referred to in the present invention means that 5 g of precipitated barium sulfate is added to an Erlenmeyer flask (1
00cc), add 50cc of water and boil for 5 minutes,
To reduce the amount, add boiled water in advance and cool to 20 ° C., then use a glass electrode pH meter to measure JIS Z-8802.
It is the value measured by the pH measuring method. Measurement is about 20 ℃
Try to finish within 10 minutes. When the pH value measured in this way is less than 3.0, the obtained light-diffusing polycarbonate becomes yellowish.
On the other hand, when the pH value exceeds 7.5, the melt viscosity of the polycarbonate having a light diffusing property lowers, which causes troubles during molding, and it becomes difficult to achieve the object of the present invention.

The average particle size of titanium oxide used in the present invention is not limited, but it is preferably 0.05 to 1 μm from the viewpoint of transparency and light diffusion of the final composition. When the average particle diameter of titanium oxide is 0.05 μm to 1 μm, a particularly good synergistic effect can be imparted in obtaining effective milky white translucency. There is no particular limitation on the mixing method and the mixing order of the polycarbonate and the above compounds, and they can be mixed by a known mixer such as a tumbler or a Henschel mixer and melt-kneaded.

At the time of mixing, known additives such as a release agent, an antistatic agent, an antioxidant, an ultraviolet absorber, a flame retardant, a dye and pigment may be added, if necessary.

The present invention will be specifically described below with reference to examples, but the invention is not limited to these examples. "Parts" are based on weight basis.

[0014]

EXAMPLES Materials used in Examples and Comparative Examples are as follows. PC: viscosity average molecular weight 30,000, MFR = 2.6 g / 10 min (MFR measurement condition 28
0 ° C., 2.16 kgf) Barium sulfate: pH 7.0, average particle size 8.1
μm Barium sulfate: pH 4.1, average particle size 2.6
μm Barium sulfate: pH 2.5, average particle size 6.3
μm Barium sulfate: pH 8.2, average particle size 4.5
μm Calcium carbonate: Average particle size 4.9 μm Titanium oxide: Average particle size 0.25 μm

Pellets of the materials having the specific compounding amounts shown in Table 1 were obtained by a single screw extruder at a kneading temperature of 280 ° C., dried in a vacuum dryer (120 ° C.) for 24 hours, and then their MFR was measured. Also, a 3 mm thick plate was molded at a molding temperature of 280 ° C., and the total light transmittance and the light diffusion transmittance were measured by Nippon Denshoku Industries Co., Ltd.
It was measured by SZ-Σ90 manufactured by. Also, the yellow index (hereinafter referred to as YI) is SZ-Σ9 manufactured by Nippon Denshoku Industries Co., Ltd.
It was measured with a colorimeter of 0. The YI measurement method was a reflection method in which a standard white plate was placed on the side opposite to the color measurement surface. The Izod impact value (description in the table: Iz value) was obtained according to ASTM D256 on a 1/4 inch test piece.

[0016]

[Table 1]

[0017]

[Table 2]

Table 1 shows examples of light diffusing polycarbonates. As a result, the same total light transmittance and light diffusion transmittance were obtained for both barium sulfate and calcium carbonate.
MFR becomes high when barium sulfate (Comparative Example 2) and calcium carbonate (Comparative Example 3) of 8.2 are used. Moreover, it was confirmed that YI was increased with barium sulfate having a pH of 2.5 (Comparative Example 1).

Table 2 shows examples of light diffusing and milky white translucent polycarbonates. As a result, except for Comparative Example 4, milky white was translucent, but with barium sulfate having a pH of 2.5 (Comparative Example 4), YI was high, whiteness was impaired, and yellowing did not occur, resulting in no milky white translucent. In addition, barium sulfate having a pH of 8.2 (Comparative Example 5) and calcium carbonate (Comparative Example 6) had MF.
It was confirmed that R was high.

In addition, in the examples using calcium carbonate (Comparative Examples 3 and 6), the Izod impact strength (Iz value) is remarkably lowered. It was clarified that the use of precipitated barium sulfate is effective for maintaining the physical properties of polycarbonate.

[0021]

The light-diffusing or milky white translucent polycarbonate resin according to the present invention has a good light-diffusing property even though the total light transmittance is high. In addition, the original melt viscosity of the base resin, polycarbonate, is not reduced. Therefore, at the time of molding, there is no concern about molding defects due to a decrease in viscosity, for example, burrs of molded products, damage of the mold due to biting of the molded product into the mold, and the like as a light-diffusing or milky white translucent polycarbonate resin composition. Applications can be expected.

Claims (2)

[Claims] 1. An average particle diameter of 0.1 to 20 μm and a pH of 3.0 to 7.5 with respect to 100 parts by weight of a polycarbonate resin.
The light-diffusing polycarbonate resin composition is characterized by containing 0.5 to 10 parts by weight of precipitated barium sulfate in the range of 1. 2. The light-diffusing polycarbonate resin composition according to claim 1, wherein 0.001 to 0.2 part by weight of titanium oxide is added to 100 parts by weight of the polycarbonate resin. Transparent polycarbonate resin composition.