Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-08-22
2003-12-02
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S013000, C524S425000, C524S426000, C524S427000
Reexamination Certificate
active
06656982
ABSTRACT:
The present invention relates to a woody thermoplastic resin composition which is prepared by incorporating a certain specific additive into a woody thermoplastic resin comprising a thermoplastic resin and wood flour and which may be widely utilized in the fields where wood-like appearance is required.
PRIOR ART
A wood has been extensively used as a construction material. However, the articles made from wood have disadvantages in their inherent nature of combustibility, durability, weather resistance, etc. Also, an environmental disruption by deforestation has become a serious problem. Under these circumstances, it is well known that a molded article having a wood-like appearance may be prepared from a mixture of a thermoplastic resin and wood flour as wood replacement. In recent years, there have been an increase in the case where wood flour-containing thermoplastic resin is used as the interior and exterior materials for house such as floor, ceiling, banister, window frame, doorframe, veranda and the like.
However, wood flour-containing thermoplastic resin causes problems of forming rust on the surface of metals such as screw, cylinder, mold, etc. in the molding machine during molding possessing such as extrusion molding or injection molding. In addition, volatile substance such as the decomposition product of the resin, water and the like generate during molding processing to cause problems of foaming the molded article and forming silver stripe on the surface of the molded article. To prevent these problems the following techniques were already proposed.
(1) A technique for prevent rust by a method which comprises incorporating at least one compound selected from the group consisting of hydrotalcites, zeolites, alkaline earth metal oxides or carbonates salts, fibrous magnesium oxysulfates, metal salts of hydrofatty acids and hindered amine light stabilizers into a polyolefin composition comprising a polyolefin and a plastic modifying agent mainly consisting of waste paper pulp (Japanese Patent Laid-Open No. Hei 11-60830). Among alkaline earth metal oxides or carbonates salts for use in said technique, oxide or carbonate of magnesium and calcium are the constituent ingredients of dolomite involving in the present invention. However, there is neither description nor suggestion in said prior art reference with respect to not only dolomite which is a magnesium-calcium complex salt for use in the present invention but also rust preventive effect to be caused when dolomite was incorporated into a woody thermoplastic resin.
(2) A technique for suppressing the generation of volatile substances by a method which comprises incorporating rice hull into a thermoplastic resin composition containing a basic filler such as magnesium oxide, calcium oxide, calcium carbonate or calcium hydroxide (Japanese Patent Laid-Open No. Sho 63-202661). Although a basic filler such as magnesium oxide, calcium oxide, calcium carbonate or calcium hydroxide for use in said technique are the constituent ingredients of dolomite involving in the present invention, there is neither description nor suggestion in said prior art reference with respect to not only dolomite which is a magnesium-calcium complex salt for use in the present invention but also volatile substances-suppressing effect to be caused when dolomite was incorporated into a woody thermoplastic resin.
There was practically incorporated into a woody thermoplastic resin composed of wood flour and thermoplastic resin an element selected from hydrotalcites, zeolites, alkaline earth metal oxides or carbonates salts, fibrous magnesium oxysulfates, metal salts of hydrofatty acids and hindered amine light stabilizers disclosed in Japanese Patent Laid-Open No. Hei 11-60830 and further the basic filler disclosed in Japanese Patent Laid-Open No Sho 63-202661. As the results, in any case the rust preventive effect and volatile substance-reducing effect could not be achieved sufficiently.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a woody thermoplastic resin composition (a wood flour-containing thermoplastic resin composition) which can prevent the rusting on the surface of metals including screw, cylinder and mold in the molding machine and at the same time which can suppress the generation of the volatile substances during heat molding processing such as extrusion molding and injection molding.
As a result of having ardently studied to achieve the above object, the present inventors have found that a thermoplastic resin composition comprising incorporating a specific amount of dolomite into a woody thermoplastic resin composed of a thermoplastic resin and wood flour in a specific ratio has excellent effect to prevent the occurrence of rust on the surface of metals including screw, cylinder and mold in the molding machine and to suppress the generation of volatile substance during molding processing such as extrusion molding and injection molding. The present invention is based on the above finding.
That is, the present invention is a thermoplastic resin composition which comprises (A) 100 parts by weight of a thermoplastic resin, (B) 5-150 parts by weight of wood flour, and (C) 0.01-20.0 parts by weight, based on the total of the components (A) and (B), of dolomite and which has excellent rust-preventive effect on the surface of metals including screw, cylinder and mold in the molding machine and volatile substances-reducing effect during molding processing such as extrusion molding and injection molding.
Also, by using a thermoplastic resin composition which comprising (A) 100 parts by weight of a thermoplastic resin, (B) 5-150 parts by weight of wood flour, and (C) 0.01-20.0 parts by weight, based on the total of the components (A) and (B), of natural dolomite and/or a synthetic dolomite consisting of magnesium carbonate-calcium carbonate, the rust preventive and volatile substances-reducing effects may be enhanced.
Also, a thermoplastic resin composition comprising (A) 100 parts by weight of a thermoplastic resin, (B) 5-150 parts by weight of wood flour, and (C) 0.01-20.0 parts by weight, based on the total of the components (A) and (B), of dolomite consisting of magnesium carbonate-calcium carbonate complex salt in which the weight ratio of magnesium to calcium is 5:95-95:5 in terms of MgO:CaO exerts the increased rust preventive and volatile substances-reducing effects.
Furthermore, a thermoplastic resin composition comprising (A) 100 parts by weight of a thermoplastic resin, (B) 5-150 parts by weight of wood flour, and (C) 0.01-20.0 parts by weight, based on the total of the components (A) and (B), of light burned dolomite prepared by light burning a dolomite consisting of magnesium carbonate-calcium carbonate complex salt in which the weight ratio of magnesium to calcium is 5:95-95:5 in terms of MgO:CaO exerts significantly increased rust preventive and volatile substances-reducing effects.
A thermoplastic resin for use in the present invention may be one which is usually being used. Examples of the thermoplastic resin include polyvinyl chloride, vinyl chloride-related resin such as chlorinated polyvinyl chloride, styrene-related resins such as polystyrene(PS), high-impact polystyrene(HIPS), syndiotactic polystyrene, acrylonitrile-butadien-styrene copolymer (ABS resin), acrylonitrile-butadien-styrene-(&agr;-methyl) styrene copolymer, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-ethylene-styrene copolymer (AES resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin) and the like; polyesters such as poly(ethylene terephthalate), poly(butylene terephthalate), polyacrylate and the like; polyamides such as nylon 6, nylon 12, nylon 66, nylon 610, nylon 612, nylon MXD6 and the like; polycarbonate, polyacetal, vinyl acetate resin, ethylene- vinyl acetate resin, poly(vinyl alcohol), poly (vinyl acetal), polyphenylene oxide, polysulfone, polyether sulfone, polyphenylene sulfide, their blend resin (polymer alloy), etc.
Wood flour for use in the present invention may be one which is generally being used. E
Anzai Yoshihito
Kubo Michihiro
Ohno Hirokazu
Yasuda Naoki
Yoshimura Shigeto
Ajinomoto Co. Inc.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Szekely Peter
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