Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1991-06-25
1993-05-04
Hoke, Veronica P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524100, 524102, 524208, 524291, 524336, 524337, C08K 53435, C08K 53475, C08K 520, C08K 513
Patent
active
052082792
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INDUSTRIAL APPLICATION
The present invention relates to a polyacetal resin composition excellent in weathering (light) resistance. More particularly, the present invention provides a polyacetal resin composition extremely excellent in weathering resistance which is prepared by adding a weathering stabilizer and a specific graft copolymer to a polyacetal resin, and a molded article thereof.
PRIOR ART
As well known, a polyacetal resin has recently been used in an extremely wide field as an engineering plastic excellent in physical characteristics such as mechanical and electrical properties and chemical characteristics such as resistances to chemicals and heat. As the application field of a polyacetal resin has enlarged, however, the resin has been frequently required to exhibit unique properties as the material. One of such unique properties is weathering (light) resistance and the resin has been expected to be further improved in this respect. That is, automobile interior or exterior trim parts and components of electrical appliances and business machines suffer from various troubles in long-term service depending upon the service conditions such as exposure to sunlight, fluorescent lamp, rain or the open air. For example, they discolor, lose their surface smoothness to exhibit lowered gloss, or cause surface crack to result in impaired surface appearance. In order to overcome these disadvantages, it has been proposed to improve the weathering (light) resistance of a polyacetal resin by the addition of various weathering (light) stabilizers and/or polycarbonate or acrylic resins thereto.
Although the weathering (light) resistance of a polyacetal resin is improved to some extent by these means, a molded article made from the resulting composition is not always satisfactory in respect of surface appearance (such as crack and gloss) and mechanical properties, when exposed to sunlight (ultraviolet rays) and rain in the outdoor for a long period of time. Therefore, a polyacetal resin composition further improved in weathering (light) resistance has been frequently demanded.
Even if the amount of the weathering (light) stabilizer or acrylic resin to be added is increased for the purpose of satisfying the demand, the improvement attained by the addition thereof has a limit. Further, the increase in the amount of such additive has various disadvantages and problems that it brings about lowering in the mechanical properties (particularly, tensile elongation and Izod impact strength) and that the resulting composition fails in mold release, sticks in cavity or deposits on the mold surface (i.e., forms so-called mold deposit) in molding, so that the resulting molded article is poor in dimensional accuracy and surface appearance and that the frequency of mold cleaning increases to lower the working efficiency in molding.
DISCLOSURE OF THE INVENTION
The inventors of the present invention have eagerly studied for the purpose of further improving the weathering (light) resistance of a polyacetal resin in outdoor service without impairing the characteristics inherent in the resin and have accomplished the present invention.
Namely, the present invention relates to a weather resistant polyacetal resin composition which comprises (co)polymer and (b) one or more vinyl (co)polymers which are chemically bonded to each other to form a branched or crosslinked structure.
The polyacetal resin (A) to be used in the present invention is a polymer mainly composed of oxymethylene (-CH.sub.2 O-) units, which may be either a polyoxymethylene homopolymer or a copolymer, terpolymer or block copolymer containing small amounts of other constituent units in addition to the oxymethylene units. Further, these (co)polymers may be linear, branched or crosslinked. Furthermore, the degree of polymerization thereof is not particularly limited.
Preferred examples of the weathering (light) stabilizer (B) to be used in the present invention include 1 benzotriazoles, 2 benzophenones, 3 aromatic benzoates, 4 cyanoacrylates, 5 oxalanilide
REFERENCES:
patent: 3749755 (1973-07-01), Bronstert et al.
patent: 4556690 (1985-12-01), Nakawaga
patent: 4639488 (1987-01-01), Schuette et al.
patent: 4975478 (1990-12-01), Okuda
patent: 5039741 (1991-08-01), Burg et al.
patent: 5059644 (1991-10-01), Kosinski
patent: 5079282 (1992-01-01), Okuda
patent: 5118734 (1992-06-01), Katsumata
Hoke Veronica P.
Polyplastics Co. Ltd.
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