Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1996-10-25
1998-06-02
Zitomer, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525154, 525398, 525401, 525523, 525529, C08L 5902, C08L 5904
Patent
active
057601380
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is related to polyacetal resin compositions, and, in more detail, to polyacetal resin compositions having improved heat aging resistance and creep resistance and which present no problems of deterioration of physical properties at the welded portion.
2. Description of the Related Art
Since polyacetal resins have superior fatigue properties, friction and abrasion resistances and superior balance of mechanical properties among plastic materials, they are widely used as automobile, electric motor and electronic parts.
However, the polyacetal resins present the problem that if they are repeatedly used at high temperatures of 90.degree.-120.degree. C. for a long time, generally they are easily acid aged, their superior mechanical properties cannot be maintained and are found to be sharply worsened.
Therefore, it is necessary to improve their heat aging resistance (long-time thermal stability) in order to use the polyacetal resins at high temperatures for a long time, and various improvements have been attempted so far for this purpose. For example, methods of adding polyamides, antioxidants, such as polycarbodiimide and heat stabilizers to the polyacetal resins are described in U.S. Pat. No. 4,098,843 and U.S. Pat. No. 4,845,161.
As the polyacetal resins with improved heat aging resistance and creep resistance (long-time oil resistance), moreover, polyacetal resin compositions consisting of polyacetal resins and compounds having at least one functional group selected from the epoxy group, nitrile group and oxazolyl group have been known (TK Heisei3(1991)-118909).
SUMMARY OF THE INVENTION
However, the deterioration of physical properties, such as heat aging resistance, etc., of the portions where injected or extruded resins from feed entrances or feeding gates of different resins are merged inside a mold, i.e. the welding portions, has still not been sufficiently improved.
This invention aims at providing polyacetal resin compositions having improved heat aging resistance and creep resistance and no problems with deterioration of physical properties at the welding portions.
The purpose of the invention is to provide polyacetal resin compositions having improved heat aging resistance and creep resistance and no problem with deterioration of the physical properties at the welded portion.
Polyacetal resin compositions characterized in that they are polyacetal resin compositions essentially consisting of a polyacetal resin, an olefin polymer containing a glycidyl group on the side chain and a styrene polymer having an oxazolyl group, the total content of the said olefin polymer having a glycidyl group on the side chain and the said styrene polymer having an oxazolyl group is 0.1-15 weight % with respect to the said polyacetal resin composition, and the content of the said styrene polymer having an oxazolyl group is 50-200 weight parts with respect to 100 weight parts of the said olefin polymer containing a glycidyl group on the side chain.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a transmission electron micrograph of a test piece II of Example 1.
FIG. 2 is a transmission electron micrograph of a test piece II of Example 4.
FIG. 3 is a transmission electron micrograph of a test piece III of Example 4.
DETAILED DESCRIPTION
As a result of earnest studies to solve the problems described above, the inventors achieved this invention by discovering that polyacetal resin compositions having improved heat aging resistance and creep resistance and no problems with deterioration of physical properties at the welding portions were obtained by compounding given amounts of an olefin polymer containing a glycidyl group on the side chain and a styrene polymer having an oxazolyl group with a polyacetal resin.
That is, this invention is related to polyacetal resin compositions characterized by the fact that they are polyacetal resin compositions, essentially consisting of an olefin polymer having a glycidyl group on the side chain and a styrene polymer
REFERENCES:
patent: 4098843 (1978-07-01), Johnson
patent: 4845161 (1989-07-01), Richardson
patent: 5418286 (1995-05-01), Takahashi et al.
patent: 5523341 (1996-06-01), Kobayashi et al.
E. I. Du Pont de Nemours and Company
Zitomer Fred
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