Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-04-09
2004-02-03
Mullis, Jeffrey (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S502000, C524S501000, C524S504000, C525S071000
Reexamination Certificate
active
06686411
ABSTRACT:
FIELD OF THE ART
This invention relates to a vinyl chloride-based resin composition which is highly excellent in weatherability, impact resistance, gloss and extrusion molding properties.
BACKGROUND ART
Because of having a low price and favorable mechanical and chemical properties, molded articles made of vinyl chloride-based resins have been widely used in various fields. However, these products have some disadvantages such that having only insufficient impact resistance, having a processing temperature close to the thermal decomposition temperature and thus being moldable only within a narrow temperature range, and taking a long time to achieve the molten state.
To solve the problem of having the insufficient impact resistance, a number of methods have been pointed out hitherto. Among all, it has been a common practice to use MBS resins and ABS resins obtained by graft-copolymerizing butadiene rubber-based polymers with methyl methacrylate, styrene or acrylonitrile.
Although the impact resistance can be improved by blending these MBS resins and ABS resins with vinyl chloride-based resins, the weatherability is deteriorated, and there arises a problem that the thus produced molded articles show considerably worsened impact resistance when used outdoors. Accordingly, it is proposed to improved the weatherability of the MBS resins and impart a good impact resistance thereto by graft-polymerizing an alkyl acrylate rubber-based polymer free from any double bonds with methyl methacrylate, an aromatic vinyl compound and an unsaturated nitrile (JP-B-51-28117 and JP-B-57-8827; the term “JP-B” as used herein means an “examined Japanese patent publication”).
In case of using the graft copolymer obtained by this method, the molded vinyl chloride-based resin articles thus produced have an excellent weatherability and, therefore, appropriately usable in the field of constructional materials with a need for a long-lasting weatherability such as window frames and siding sheets.
As a technique for improving the processability of these vinyl chloride-based resins, it is proposed to add form about 0.5 to 5% of a copolymer containing a repeating unit derived from methyl methacrylate as the main component as a processing aid (JP-B-52-49020). Generally, by using this processing aid in the extrusion molding of window frames or siding sheets, the gelation of the vinyl chloride-based resin is promoted and thus favorable molded articles can be obtained.
Some of the vinyl chloride-based resin compositions for the field of constructional materials contain calcium carbonate or titanium oxide as a filler. Among all, calcium carbonate has been widely employed since it is not only less expensive and thus exerts a cost-down effect but also contributes to the elevation of the heat deforming temperature, the improvement in insulating resistance and the improvement in the dimensional stability. In case of, for example, window frames, it is needed to produce molded articles having smooth and glossy surface, but no method has been developed hitherto to meet the needs for improving the gloss. That is to say, although the gloss is improved by using a large amount of the processing aid, the effect of improving the gloss is still insufficient and, moreover, there arises another problem of the worsening of the impact resistance. Although the gloss can be improved by reducing the content of calcium carbonate, this method is undesirable since it results in an increase in the cost. Although improved gloss can be obtained by elevating the molding temperature, there arise some problems in this case, for example, a decrease in the discharge due to an increase in the extrusion torque and the occurrence of the heat decomposition of vinyl chloride. Accordingly, it is very difficult to simultaneously achieve a favorable gloss, a high impact resistance, a high productivity and a low cost.
SUMMARY OF THE INVENTION
The invention, which has been made by taking the problems encountering in the conventional art into consideration, aims at providing a vinyl chloride-based resin composition from which highly glossy molded articles with favorable surface properties can be obtained without worsening the impact resistance.
The inventors have conducted intensive studies to solve the problems as described above. As a result, they have found out that highly glossy molded articles can be obtained without worsening the impact resistance by using a hard polymer containing an acrylate rubber-based graft copolymer and a repeating unit derived from methyl methacrylate with an extremely high molecular weight as the main components.
Accordingly, the present invention provides the following vinyl chloride-based resin composition which can achieve the object mentioned above.
1. A vinyl chloride-based resin composition which comprises:
(A) 100 parts by weight of a vinyl chloride-based resin;
(B) from 1 to 30 parts by weight of a graft copolymer which is obtained by graft-polymerizing, in the presence of from 70 to 95 parts by weight of a crosslinked acrylic rubber-like polymer (b-
1
), from 5 to 30 parts by weight of a vinyl monomer (b-
2
) while controlling the sum of (b-
1
) and (b-
2
) to 100 parts by weight;
(C) from 0.1 to 5 parts by weight of a methyl methacrylate-based two stages polymer which is obtained by, in the presence of a polymer obtained by emulsion-polymerizing from 50 to 100 parts by weight of a monomer or a monomer mixture (c-
1
) comprising from 50 to 100% by weight of methyl methacrylate, from 0 to 50% by weight of a monomer selected from the group consisting of alkyl methacrylates other than methyl methacrylate and alkyl acrylates and from 0 to 20% by weight of a vinyl monomer copolymerizable therewith, while controlling the sum of the monomers to 100% by weight, and a solution of 0.1 g of the polymer in 100 ml of chloroform showing a specific viscosity of 0.7 or more at 30° C., adding from 0 to 50 parts by weight of a monomer or a monomer mixture (c-
2
) comprising from 0 to 50% by weight of methyl methacrylate, from 50 to 100% by weight of at least one monomer selected from the group consisting of alkyl methacrylates other than methyl methacrylate and alkyl acrylates and from 0 to 20% by weight of a vinyl monomer copolymerizable therewith, while controlling the sum of the monomers to 100% by weight, while controlling the sum of (c-
1
) and (c-
2
) to 100 parts by weight, and a solution of 0.1 g of the two stages polymer in 100 ml of chloroform showing a specific viscosity of 0.5 or more at 30° C.; and
(D) from 1 to 20 parts by weight of calcium carbonate.
2. The vinyl chloride-based resin composition of 1 above wherein the methyl methacrylate-based two stages polymer (C) is a methyl methacrylate-based two stages polymer a solution of 0.1 g of which in 100 ml of chloroform shows a specific viscosity of 0.7 or more at 30° C.
3. The vinyl chloride-based resin composition as of 1. or 2. above wherein the graft copolymer (B) is a graft copolymer which is obtained by polymerizing, in the presence of from 70 to 95 parts by weight of a crosslinked rubber polymer comprising from 70 to 99.99% by weight of an alkyl acrylate having an alkyl group carrying form 2 to 8 carbon atoms, from 0.01 to 5% by weight of a polyfunctional monomer and from 0 to 30% by weight of a monomer copolymerizable therewith while controlling the sum of the monomers to 100% by weight, from 5 to 30 parts by weight of graft monomer component(s) comprising from 60 to 100% by weight of methyl methacrylate and from 0 to 40% by weight of at least one monomer selected from the group consisting of alkyl methacrylates other than methyl methacrylate, alkyl acrylates, unsaturated nitriles and aromatic vinyl compounds, while controlling the sum to 100 parts by weight.
4. A molded article obtained by molding the composition as claimed in any one of 1 to 3 above.
5. A window frame or a door frame obtained by molding the composition as claimed in 4 above.
Best Mode of the Invention
The vinyl chloride-based resin (A) to be used in the invention includes vinyl chloride homopolymer
Iguchi Hirokazu
Kadokura Mamoru
Nakajima Nobumasa
Yui Koji
Armstrong Kratz Quintos Hanson & Brooks, LLP
Kaneka Corporation
Mullis Jeffrey
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