Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-02-22
2003-07-08
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S141000, C524S310000, C525S067000
Reexamination Certificate
active
06590016
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a flame retardant resin composition, and more particularly, it relates to a non-halogen-based flame retardant thermoplastic resin composition which is excellent in impact resistance, heat resistance, fluidity, flame retardance and extrusion-production stability.
Conventionally, flame retardant ABS resins have been extensively used in various applications such as electric and electronic devices and office automation devices because these resins are excellent in appearance of molded products produced therefrom, moldability, mechanical properties or the like. In recent years, there is a tendency that the use of halogen-based flame retardants in these products should be avoided from the viewpoint of environmental protection. For this reason, there have been presently marketed such flame retardant resin materials containing a PC (polycarbonate)/ABS alloy resin as a base resin and a phosphate-based flame retardant.
However, in the case where the PC/ABS alloy resin is used in combination with the phosphate-based flame retardant, the obtained materials tend to show a poor extrusion-production stability, and also tends to be deteriorated in chemical resistance.
In the case where such a polycarbonate resin having a low molecular weight is used in combination with the phosphate-based flame retardant to enhance extrusion stability, the obtained composition is deteriorated in impact resistance in spite of the enhanced extrusion stability. Further, such a composition generally contains polytetrafluoroethylene as an anti-dripping agent. However, since the polytetrafluoroethylene usually has a molecular weight as high as not less than 1,000,000, it becomes difficult to uniformly disperse the polytetrafluoroethylene in the resin, so that the obtained composition has problems such as deteriorated impact resistance and unstable production of strands when pelletized by an extruder.
As a result of the present inventors' earnest studies to solve the above problems, it has been found that the problems can be solved by using a specific rubber-reinforced thermoplastic resin, a specific aromatic polycarbonate, a specific phosphate-based flame retardant and specific additives in combination. The present invention has been attained on the basis of this finding.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a non-halogen-based flame retardant thermoplastic resin composition which is free from the above problems and excellent in impact resistance, heat resistance, fluidity, flame retardance and extrusion-production stability.
To attain the above aim, in accordance with the present invention, there is provided a flame retardant thermoplastic resin composition comprising:
(A) 10 to 40 parts by weight of a rubber-reinforced resin produced by graft-polymerizing a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound as main ingredients in the presence of a rubber polymer comprising particles having a particle size of not more than 150 nm in an amount of 0 to 15% by weight, particles having a particle size of from more than 150 to less than 350 nm in an amount of 60 to 100% by weight and particles having a particle size of not less than 350 nm in an amount of 0 to 25% by weight; and
(B) 90 to 60 parts by weight of an aromatic polycarbonate having a viscosity-average molecular weight of 16,000 to 30,000, with the proviso that the total amount of the components (A) and (B) is 100 parts by weight;
said composition further comprising:
(C) a phosphate compound represented by the general formula (I):
wherein R
1
, R
2
, R
3
and R
4
are independently phenyl group or xylenyl group; X is m-phenylene group or 2,2-bis(4′-phenylene)propane group; and n is 0.5 to 1.2,
in an amount of 8 to 25 parts by weight based on 100 parts by weight of the sum of said components (A) and (B); and
(D) a component comprising 10 to 70% by weight of polytetrafluoroethylene (d1) and 90 to 30% by weight of a lubricant (d2) with the proviso that the total amount of (d1) and (d2) is 100% by weight, in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the sum of said components (A) and (B).
DETAILED DESCRIPTION OF THE INVENTION
The rubber-reinforced resin (A) used in the present invention may be produced by graft-polymerizing a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound as main ingredients in the presence of a rubber polymer having a specific particle size distribution.
Meanwhile, the rubber-reinforced resin (A) used in the present invention may be in the form of a mixture obtained by blending the graft copolymer produced by the above graft polymerization, with a separately produced polymer or copolymer of at least one monomer component selected from the group consisting of the above aromatic vinyl compounds and vinyl cyanide compounds.
As the rubber polymers, there may be exemplified polybutadiene, styrene-butadiene copolymers, styrene-isoprene copolymers, butadiene-acrylonitrile copolymers, ethylene-propylene or ethylene-propylene-non-conjugated diene copolymers, ethylene-butene-1 or ethylene-butene-1-non-conjugated diene copolymers, isobutylene-isoprene copolymers, acrylic rubbers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, polyurethane rubbers, silicone rubbers or the like. Specific examples of the styrene-butadiene copolymers may include styrene-butadiene random copolymers, styrene-butadiene block copolymers or the like. In addition, hydrogenated products of the above-described polybutadiene, styrene-butadiene copolymers or the like may also be used as the rubber polymers. These rubber polymers may be used alone or in the form of a mixture of any two or more thereof. Among these rubber polymers, polybutadiene, styrene-butadiene copolymers, ethylene-propylene or ethylene-propylene-non-conjugated diene copolymers, hydrogenated diene-based polymers or copolymers and silicone rubbers are preferred.
In the present invention, the particle size distribution of the rubber polymer is very important. The rubber polymer is required to have the following particle size distribution. Namely, the rubber polymer contains particles having a particle size of 50 to 150 nm in an amount of 0 to 15% by weight, preferably 0 to 12% by weight; particles having a particle size of from more than 150 to less than 350 nm in an amount of 60 to 100% by weight, preferably not less than 65 to 100% by weight; and particles having a particle size of 350 to 2000 nm in an amount of 0 to 25% by weight, preferably 0 to 20% by weight.
When the particle size distribution of the rubber polymer which largely influences the rubber orientation upon molding, lies within the above-specified range, the obtained composition can exhibit a good practical impact resistance. Here, the “rubber orientation” means such a phenomenon that rubber particles are deformed in the flowing direction by shear force applied upon melding. When the rubber orientation is increased, the practical impact resistance of the composition becomes deteriorated.
When the content of the rubber polymer particles having a particle size of not more than 150 nm is exceeds 15% by weight, the stress distribution effect by rubber particles within the molded product may be deteriorated, resulting in poor practical impact resistance thereof. When the content of the rubber polymer particles having a particle size of not less than 350 nm exceeds 25% by weight, the rubber orientation becomes considerably large, resulting in poor practical impact resistance and deterioration in burning evaluation rating (flame retardance).
The rubber polymer has a gel fraction of preferably 40 to 90% by weight, more preferably 50 to 90% by weight, especially preferably 60 to 90% by weight. When the gel fraction of the rubber polymer is less than 40% by weight, the obtained composition may be deteriorated in impact resistance, stiffness, flame retardance and the like. On the contrary, when the gel fraction o
Higaki Keigo
Itoh Hiroyuki
Miyazaki Hiroaki
Noro Masahiko
Buttner David J.
Nixon & Vanderhye P.C.
Techno Polymer Co., Ltd.
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