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
2001-10-02
2003-12-30
Reddick, Judy M. (Department: 1713)
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...
C428S328000, C428S424400, C428S516000, C524S476000, C524S501000, C524S504000, C524S517000, C524S519000, C524S522000, C525S192000, C525S207000, C525S214000, C525S221000
Reexamination Certificate
active
06670414
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention provides a binder resin composition that forms a coated film with excellent and well balanced adherence, water resistance, weather resistance and flexibility without primer treatment on the surface of polyolefinic resin moldings.
A binder resin composition containing a mixture of carboxyl group-containing chlorinated polyolefin (1) with 1 to 10 wt. % of grafting rate of at least one kind of unsaturated carboxylic acid monomer selected from carboxylic acids or carboxylic anhydrides and 5 to 50 wt. % of chlorine content, with ethylene-vinyl acetate copolymer (II).
2. Description of the Related Art
Because of high productivity, broad degree of freedom for design and many advantages such as light weight, corrosion and shock resistance, in recent years, plastics have been used broadly as the materials of choice for automotive parts, electrical parts, building materials, etc. Above all, because of low price and many excellent properties such as moldability, chemical resistance, heat resistance, water resistance and good electrical characteristics, polyolefinic resin moldings are used extensively as industrial materials, ranking them as one of the materials for which the growth of demand thereof is most expected in future. For example, polyolefinic resin moldings are used for prime materials of exterior parts such as bumper in automotive use and it is usual to paint the surface thereof to provide the design properties as well as improved weather resistance.
However, different from the moldings of synthetic resins with polarity such as polyurethane resin, polyamide resin, acrylic resin and polyester resin, polyolefinic resin moldings are nonpolar and crystalline, hence they have drawbacks such as poor paint adhesion. For this reason, an exclusive primer is coated prior to coating with base paint to enhance the adherence between base paint film and said prime materials and, as the case may be, to enhance the water resistance, then the base paint is coated thereon for weather resistance etc.
So far, for the primer, chlorinated polyolefin with strong adherence to polyolefinic resin moldings is used as a binder resin.
In recent years, aiming at the reduction of cost in painting process of automotive exterior parts, the development of base paints (hereinafter referred to as primeness base paint) capable of being used without coating the primer beforehand onto polyolefinic resin moldings is implemented. To obtain the primeness base paint, it is conceivable to formulate chlorinated polyolefin being a component contained in the primer with acrylic polyol that works to improve the weather resistance etc.
However, since the chlorinated polyolefin has poor tolerance to heat or ultraviolet rays, if formulating chlorinated polyolefin into base paint, then problems to deteriorate chlorinated polyolefin by heat or ultraviolet rays imposed directly or through clear film coated on the surface, and the like arise.
As described above, since the chlorinated polyolefin has poor tolerance to heat or ultraviolet rays, epoxy compounds containing glycidyl groups are added generally as stabilizers. However, only with epoxy compound as the only additive, the epoxy migrates out of the system over the time after formation of coated film, resulting in insufficient effect as a stabilizer.
To prevent the migration of epoxy compound, a method of reacting epoxy compound with chlorinated polyolefin is desirable. Primer compositions or base paint compositions with epoxy compounds reacted with chlorinated polyolefin are disclosed, for example, in Japanese Patent Publication Nos. Sho 63-50381 and Hei 1-16414, Japanese Unexamined Patent Publication No. Hei 8-100032, etc. In these, epoxy compound is added to carboxyl group-containing chlorinated polyolefin obtainable by graft polymerizing unsaturated carboxylic acid or its anhydride onto polyolefin, followed by chlorination, which is then painted onto polyolefinic resin moldings and then the carboxyl group is reacted with epoxy compound, or carboxyl group and epoxy compound are reacted beforehand in the presence of a catalyst such as tertiary amine or tin compound, which is then painted.
Among these compositions, however, in the case of epoxy compound added and painted, because of poor reactivity between carboxyl group and epoxy compound, the epoxy compound is liable to migrate out of system over the time, resulting in insufficient stability to heat or ultraviolet rays. While, in the case of reacting carboxyl group with epoxy compound beforehand in the presence of a catalyst such as tertiary amine or tin compound, followed by painting, carboxyl group and epoxy compound lead to crosslinking, resulting in poor adherence onto polyolefinic resin moldings. Further, to solve this, in Japanese Unexamined Patent Publication No. Hei 10-204372, a binder resin composition, in which a monomer with ethylenic unsaturated bond and glycidyl group is graft polymerized onto carboxyl group-containing chlorinated polyolefin, is provided. Although this was an effective composition for preventing the migration of epoxy out of system, it was not enough in the point of the flexibility of coated film, and required the use of a flexible resin in combination. However, because of poor compatibility of chlorinated polyolefin with flexible resin, there was a problem of deteriorated storage stability of paint.
On the other hand, the polyolefin resin has been used broadly as a prime material replaceable vinyl chloride resin. For example, for the decorative sheet to be used as a decorative laminate by laminating on the surface of woody board, inorganic board and metal plate with adhesive, vinyl chloride sheet with excellent flexibility, embossing property, contamination resistance, etc. has seen broad application, but, since vinyl chloride resin can cause incinerator corrosion and acid rain due to hydrogen chloride gas at the time of incineration, thermoplastic polyolefin resins such as polypropylene and polyethylene are investigated as alternative resins (Japanese Unexamined Patent Publication Nos. Hei 8-230113, Hei 8-90740, Hei 8-1181, Hei 6-155692 and Hei 6-198831). For the adhesives to be used in their place, urethane-based, polyester-based and aqueous acrylic emulsion-based adhesives for polyolefin are mentioned, but currently, even if these adhesives are used, sufficient adhesive strength has not been obtained.
Moreover, the inventors have proposed an adhesive for polyolefin sheets previously in Japanese Unexamined Patent Publication No. Hei 9-64227. This had good adhesiveness onto some polyolefin sheets, but the adhesiveness onto various sheets was insufficient.
SUMMARY OF THE INVENTION
The purpose of the invention is to provide a binder resin composition that can be painted directly onto the surface of polyolefinic resin moldings, without primer treatment, and exhibits excellent adherence, flexibility, water resistance and weather resistance and is well balanced in these physical properties, a primer and base paint for polyolefinic resin moldings and an adhesive for polyolefinic sheets.
As a result of diligent studies to solve said aforementioned problems, the inventors have found that a composition comprising a mixture of carboxyl group-containing chlorinated polyolefin (I) with 1 to 10 wt. % of grafting rate of at least one kind of unsaturated carboxylic acid monomer selected from carboxylic acids or carboxylic anhydrides to raw material polyolefin and 5 to 50 wt. % of chlorine content, with ethylene-vinyl acetate copolymer (II) can solve said subject.
The invention relates to a binder resin composition to be used for the purpose of protecting or enhancing the appearance of polyolefinic resins, for example, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, etc., and, in more detail, it relates to a composition to be used as a binder resin for primer and base paint with excellent adherence and other physical properties onto polyolefin sheets, films and
Komoto Naosuke
Shiraishi Kazunori
Ueda Takaaki
Urata Keiji
Nippon Paper Industries Co. Ltd.
Reddick Judy M.
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