JP2581777B2 - Flame retardant polycarbonate resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a flame-retardant polycarbonate resin composition having light diffusion properties. More specifically, the present invention relates to a polycarbonate composition having excellent flame retardancy and light diffusibility having excellent non-dripping properties, and being useful as a backlight for liquid crystal displays in the optical field.

<Prior art> Conventionally, as a light diffusion plate for a backlight of a liquid crystal display,
An acrylic resin mixed with a light diffusing agent is used. However, recently, the flame retardancy and the heat resistance of the light diffusing plate used for such an application have been demanded, and the conventional acrylic resin cannot satisfy those demands.

On the other hand, polycarbonate resin has excellent heat resistance and
A polycarbonate resin composition containing a specific amount of short glass fiber and finely divided calcium carbonate dispersed therein is suitable for a light diffusion plate because it has flame retardancy that meets UL standard 94V-2. And proposed earlier (Japanese Patent Application No. 63-32596).

However, as products have become lighter and thinner, a polycarbonate resin light diffusion plate has also been required to be thinner and have higher flame retardancy.

That is, the resin composition for a light diffusion plate has excellent flame retardancy,
If a total light transmittance of about 35% or more, a half-angle of about 15 ° or more and a highly corrosive gas are generated, the internal IC substrate will be damaged, so it is desired not to generate a highly corrosive gas.

<Object of the Invention> The object of the present invention is to have excellent flame retardancy and optical characteristics, having a total light transmittance of about 35% or more and a half angle of about 15 ° or more, An object of the present invention is to provide a flame-retardant polycarbonate resin composition which does not generate a strong gas and is particularly suitable for a backlight of a liquid crystal display.

The present inventors have worked diligently to solve this problem, and as a result of intensive research, a specific amount of finely-divided calcium carbonate and a polycarbonate resin composition in which glass short fibers are dispersed, a metal salt of an organic phosphoric acid ester is further added. The present inventors have found that a polycarbonate resin composition containing polytetrafluoroethylene having a fibril-forming ability satisfies the above-mentioned various requirements, and arrived at the present invention.

<Constitution of the Invention> The present invention relates to (A) 60 to 99% by weight of a polycarbonate resin, (B) 1 to 20% by weight of finely divided calcium carbonate and (C) 0 to 39% by weight of short glass fibers, provided that (B) Ingredient +
(C) 100 parts by weight of a resin composition having a light diffusion property of ≦ 40% by weight, and (D) the following general formula [I] (Wherein, R ₁ and R ₂ are each independently an alkyl group or an aryl group which is halogen-substituted or unsubstituted, at least one of R ₁ and R ₂ is an aryl group, and R ₁ and R ₂ are When both R ₂ are aryl groups, R ₁ and R ₂ may be bonded directly or by an alkylene group, or may form one condensed ring. M represents an alkali metal.)
Flame-retardant with light diffusing properties obtained by dispersing at least one metal salt of an organic phosphate represented by the formula (1) in an amount of 0.001 to 5.0 parts by weight and (E) 0.01 to 2.0 parts by weight of polytetrafluoroethylene having a fibril-forming ability. It relates to a polycarbonate resin composition.

The polycarbonate resin used in the present invention is produced by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method. A typical example of dihydric phenol is 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 1,1-bis (4-
(Hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4
-Hydroxy-3,5-dibromophenyl) propane, 2,2
-Bis (4-hydroxy-3-methylphenyl) propane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone and the like. Preferred dihydric phenols are bis (4-hydroxyphenyl) alkanes, especially those containing bisphenol A as a main raw material. Examples of the carbonate precursor include carbonyl halide, carbonyl ester and haloformate, and specific examples thereof include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol, and a mixture thereof. In producing the polycarbonate resin, the dihydric phenol can be used alone or in combination of two or more. Also, two or more of the thus obtained polycarbonate resins may be mixed.

The viscosity average molecular weight of polycarbonate resin is generally 1
It is 10,000 to 100,000, preferably 15,000 to 60,000. When producing a polycarbonate resin having such a viscosity average molecular weight, an appropriate molecular weight regulator, a branching agent for improving processability, a catalyst for accelerating the reaction, and the like may be added.

As the finely divided calcium carbonate (B) used in the present invention, a commercially available product can be used as it is, but it is preferable that the average particle size is about 4 to 6 μm and angular.

The short glass fiber (C) used in the present invention is obtained by cutting or pulverizing glass fiber having a diameter of 5 to 15 μm to a length of 100 μm or less. As the glass, alkali-free glass, for example, E glass is preferable. The refractive index is preferably different from that of the polycarbonate used by 0.01 to 0.04. Such short glass fibers can be easily obtained from the market as milled fibers or glass powder.

The mixing ratio of these fine calcium carbonate and short glass fiber is as follows: (A) 60 to 99% by weight of a polycarbonate resin; (B) 1 to 20% by weight of finely divided calcium carbonate; (C) 0 to 39% by weight of short glass fiber; Component (B) + component (C) ≦ 40% by weight.

If the proportion of the finely divided calcium carbonate is less than 1% by weight, it is insufficient to impart light diffusibility. If the total amount of (B) the finely divided calcium carbonate and (C) the short glass fiber exceeds 40% by weight, As a result, melt molding becomes difficult, and the appearance of the obtained molded product deteriorates.

The metal salt of the organic phosphoric acid ester used in the present invention is a compound represented by the general formula [I].

In the formula, R ₁ and R ₂ are each independently an alkyl group or an aryl group, at least _one of R ₁ and R ₂ is an aryl group, and at least one of R ₁ and R ₂ is substituted with halogen. You may. Preferred examples of the alkyl group and the aryl group include a methyl group, an ethyl group, an isopropyl group, a t-butyl group, and n.
-Nonyl group, phenyl group and the like. When R ₁ and R ₂ are both an aryl group, R ₁ and R ₂ may be directly or via an alkylene group, or may form one condensed ring. For example (Where m and n are 0 or a positive integer) and the like.
M is an alkali metal, preferably sodium and potassium.

The metal salt of an organic phosphate represented by the above general formula [I] is commercially available as a nucleating agent for crystalline polymers (trade names NA-10, NA-11) from, for example, Adeka Argus, and is easily available. it can. The metal salt of a halogenated organic phosphoric ester represented by the above general formula is disclosed in
No. 47953, JP-A-61-210090, U.S. Pat.
It can be easily synthesized according to the specification of No. 70,614.

The mixing ratio of the metal salt of these organic phosphates is 0.001 to 5.5 parts by weight based on 100 parts by weight of the resin composition comprising the polycarbonate resin, the finely divided calcium carbonate and the short glass fiber.
0 parts by weight, preferably 0.005 to 2.0 parts by weight.
If the amount is less than 0.001 part by weight, the flame retardant effect is insufficient, and
If the amount exceeds 5.0 parts by weight, not only the thermal stability decreases, but also the flammability increases.

Polytetrafluoroethylene used in the present invention,
It has fibril-forming ability and is classified into type 3 according to ASTM standards. The polytetrafluoroethylene having the above-mentioned fibril-forming ability is, for example, Teflon 6J from Mitsui-DuPont Fluorochemicals Co., Ltd., or Polyflon D-1 (aqueous dispersion) from Daikin Chemical Industries, Ltd.
And are readily available.

The compounding ratio of the polytetrafluoroethylene is 0.01 to 100 parts by weight based on 100 parts by weight of the resin composition comprising the polycarbonate resin, the finely divided calcium carbonate and the short glass fiber.
2.0 parts by weight, preferably 0.05 to 1.0 part by weight.
If the amount is less than 0.01 part by weight, it is insufficient to impart non-dripping property at the time of combustion, and if it exceeds 2.0 parts by weight, the viscosity of the resin is significantly increased, which is not preferable as a molding material.

An arbitrary method is employed for producing the resin composition of the present invention. For example, a powdery polycarbonate resin and finely powdered calcium carbonate, glass short fibers, a powdery metal salt of an organic phosphate, and a powdery polytetrafluoroethylene may be dry-blended using a supermixer, a tumbler or the like. An aqueous solution of a metal salt of an organic phosphate may be added to a polycarbonate resin powder and then dried, followed by mixing fine powdered calcium carbonate, short glass fiber, and powdered polytetrafluoroethylene.

Also, any method such as adding an aqueous dispersion of polytetrafluoroethylene to a polycarbonate resin powder, drying the mixture, and mixing finely powdered calcium carbonate, glass short fibers, and a powdery metal salt of an organic phosphoric acid ester is used. However, the effect is sufficiently exhibited.

The obtained composition can be used as it is or after being formed into pellets by an extruder, and then formed into a molded product by a method such as ordinary injection molding, extrusion molding, or compression molding.

The composition of the present invention may optionally contain any additives such as stabilizers, release agents, lubricants, antistatic agents, ultraviolet absorbers,
Dyes and pigments can be added.

<Effect of the Invention> The composition of the present invention has excellent flame retardancy as compared with the conventional light diffusing polycarbonate composition, and has a total light transmittance of about 35% or more and a half angle reduction of about 15 ° or more. The light diffusing plate obtained from the present composition is suitable for a backlight of a liquid crystal display since it has excellent performance of not generating a highly corrosive gas.

<Example> Hereinafter, the present invention will be described specifically with reference to examples.

The total light transmittance and half angle were measured by the following methods.

 Total light transmittance: based on JIS K-6735.

Half angle reduction: Using a gloss meter VGS-1D manufactured by Nippon Denshoku Industries Co., Ltd., place the molded plate 1 on the sample table as shown in the figure, and light from a 5V-1.25A halogen lamp (light source 2) from immediately above. , And the intensity of the transmitted light perpendicular to the sample surface is measured by the light receiver 3, which is designated as A. The light receiver is moved in the circumferential direction as shown in the figure, and the angle γ ° at which the intensity of the transmitted light becomes A / 2 is obtained.

Examples 1 to 5 and Comparative Examples 1 to 5 Polycarbonate resin, finely powdered calcium carbonate, short glass fiber, metal salt of an organic phosphate and polytetrafluoroethylene were mixed in a blender as shown in Table 1 using a blender. Thereafter, the mixture was extruded into a pellet at a cylinder temperature of 290 ° C. using a 30 mmφ vent type extruder (Nakatani Co., Ltd .: VSK-30).

After drying these pellets at 120 ° C for 6 hours, a 5 ”x 1/2” x 2mm test was performed using an injection molding machine (Sumitomo Cycap 480/150) at a cylinder temperature of 300 ° C and a mold temperature of 100 ° C. The pieces were molded and subjected to a UL 94 fire test. The results are shown in Table 1. Further, a square plate of 150 mm × 150 mm × 2 mm was formed under the same conditions, and the total light transmittance and the half angle were measured. The results are shown in Table 1.

The symbols in the table indicate the following substances.

(A) polycarbonate resin; Teijin Chemicals Ltd. Panlite L-1250 (B) fine powder calcium carbonate; Sipron Chemical Co., Ltd. Sipron A (C) short glass fiber; Nitto Boseki Co., Ltd. PFB-101 (D) organic Metal salt of phosphate ester; Adeka Argus Co., Ltd. NA-10 (E) a metal salt of an organic phosphate ester; Adeka Argus Co., Ltd. NA-11 (F) polytetrafluoroethylene; Teflon 6J, Mitsui-Dupont Fluorochemicals Co., Ltd. (G) Metal salt of halogenated organic phosphate (H) Metal salts of halogenated organophosphates (I) Polytetrafluoroethylene; Daikin Chemical Industry Co., Ltd. Polyflon F-103 (J) Titanium oxide; Ishihara Sangyo Co., Ltd. Taipae CR-60

[Brief description of the drawings]

The figure is a diagram for explaining a method for measuring the half angle of a transmitted light beam. In the figure, 1 is a sample, 2 is a light source, and 3 is a light receiver.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 27:18)

Claims (1)

(57) [Claims] (A) 60 to 99% by weight of a polycarbonate resin (B) 1 to 20% by weight of finely divided calcium carbonate (C) 0 to 39% by weight of short glass fiber provided that component (B) + component (C) ≦ With respect to 100 parts by weight of a resin composition having a light diffusion property of 40% by weight, (D) the following general formula [I] (Wherein, R ₁ and R ₂ are each independently an alkyl group or an aryl group which is halogen-substituted or unsubstituted, at least one of R ₁ and R ₂ is an aryl group, and R ₁ and R ₂ are When both R ₂ are aryl groups, R ₁ and R ₂ may be bonded directly or by an alkylene group, or may form one condensed ring. M represents an alkali metal.)
Flame-retardant material having light diffusibility obtained by dispersing 0.001 to 5.0 parts by weight of at least one metal salt of an organic phosphate represented by the formula and 0.01 to 2.0 parts by weight of (E) polytetrafluoroethylene having a fibril-forming ability. Polycarbonate resin composition.