Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-06-11
2003-07-29
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S221000, C525S222000, C525S240000
Reexamination Certificate
active
06599980
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to an aqueous coating composition which has excellent properties to plastic materials, and a coated article.
B. Background Art
Plastic materials utilized for automotive interior parts include polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), poly(phenylene oxide) (PPO) and polycarbonate (PC). In recent years, polyolefin materials have been used often in view of cost and recyclability.
Coatings designed for interior parts are applied to these plastic materials. However, it is difficult for a paint to have good properties on polyolefin materials, because the polyolefin materials have low polarity.
In order for a coating to have good properties on the polypropylene materials, a coating composition is generally formulated using a poly(propylene chloride) resin and an organic solvent. The organic solvent forms uniform coating films and improves adhesion by swelling the materials.
However, organic solvents are also troublesome substances for working environments and fire, and besides are a cause of pollution. Organic solvents are being strictly regulated worldwide.
Accordingly, the development of aqueous coating compositions is very necessary.
Beef tallow resistance and chemical resistance such as alkaline resistance will be demanded for automotive uses.
SUMMARY OF THE INVENTION
A. OBJECT OF THE INVENTION
An object of the present invention is to provide: an aqueous coating composition, with which a 1-coat finish of plastic materials such as polyolefin materials can be performed, and which is aqueous, has high adhesion, and is excellent in beef tallow resistance and alkaline resistance; and a coated article.
B. DISCLOSURE OF THE INVENTION
The present inventors made various experiments to solve the abovementioned problems. As a result, they completed the present invention by verifying that, if an emulsion type is used as the poly(propylene chloride) resin, and if the chlorination degree and maleic anhydride moiety content thereof are adjusted to a specific ratio, and if this poly(propylene chloride) resin is combined with an emulsion of the acrylic resin or the acrylic resin modified by a small amount of poly(propylene chloride) having a high glass transition temperature within the specific ratio range, and with polycarbodiimide as a crosslinking agent, and further with a resin powder, then the amount of the organic solvent as used can be diminished, and further, the 1-coat finish of the plastic materials such as polyolefin materials can be performed, and the beef tallow resistance and chemical resistance such as alkaline resistance can also be enhanced.
An aqueous coating composition, according to the present invention, comprises: a poly(propylene chloride) resin emulsion including a poly(propylene chloride) resin which has a chlorine content of 15 to 25 weight % and a maleic anhydride moiety content of 1.0 to 5.0 weight %; an acrylic resin emulsion including an acrylic resin which is obtained by modifying the poly(propylene chloride) resin of 0 to 30 weight % and has a glass transition temperature of not lower than 90° C.; a polycarbodiimide crosslinking agent; and a resin powder,
wherein: the nonvolatile solid content of the poly(propylene chloride) resin emulsion is in the range of 10 to 30 weight %, the nonvolatile solid content of the acrylic resin emulsion is in the range of 40 to 65 weight %, the nonvolatile solid content of the polycarbodiimide crosslinking agent is in the range of 5 to 25 weight %, of the entirety of the nonvolatile solid content of the poly(propylene chloride) resin emulsion, the acrylic resin emulsion, and the polycarbodiimide crosslinking agent, and
wherein: the content of the resin powder is in the range of 5 to 10 weight % of the nonvolatile solid content of the aqueous coating composition except the resin powder.
A coated article, according to the present invention, is coated with the aqueous coating composition.
These and other objects and the advantages of the present invention will be more fully apparent from the following detailed disclosure.
DETAILED DESCRIPTION OF THE INVENTION
The aqueous coating composition, according to the present invention, comprises a resin emulsion as an essential component, wherein the resin emulsion includes a poly(propylene chloride) resin emulsion and an acrylic resin emulsion, and further comprises a polycarbodiumide crosslinking agent and a resin powder.
In the present invention, usually, the poly(propylene chloride) resin and the acrylic resin are emulsified separately from each other, and then mixed together.
As to the above resin emulsion, the poly(propylene chloride) resin or acrylic resin is particularly dispersed in an aqueous medium, and the particle surfaces thereof are stabilized with additives such as emulsifiers, surfactants, or dispersants.
(Poly(propylene Chloride) Resin):
The poly(propylene chloride) resin, which is included in the poly(propylene chloride) resin emulsion as used in the present invention, is a polypropylene derivative comprising polypropylene chloride moiety (a1) and maleic anhydride moiety (a2) as bonded to moiety (a1).
Polypropylene chloride moiety (a1) is a moiety comprising a polypropylene including a substituent chlorine. In addition, maleic anhydride moiety (a2) comprises a group as derived from maleic anhydride, and is a modified moiety as obtained by graft.
The chlorine content of the poly(propylene chloride) resin is in the range of 15 to 25 weight %. In the case where the chlorine content is less than the above range, the emulsification is difficult. In the case where the chlorine content is more than the above range, not only the adhesion to propylene materials but also the beef tallow resistance is inferior.
The maleic anhydride moiety content is in the range of 1.0 to 5.0 weight %. In the case where the maleic anhydride moiety content is less than the above range, the emulsification is difficult. In the case where the maleic anhydride moiety content is more than the above range, the adhesion to propylene materials is inferior.
The weight-average molecular weight of the poly(propylene chloride) resin is not especially limited, but is preferably in the range of 30,000 to 100,000. In the case where the weight-average molecular weight is less than 30,000, the beef tallow resistance is inferior. On the other hand, in the case where the weight-average molecular weight is more than 100,000, the emulsification is difficult.
The poly(propylene chloride) resin is obtained by the internal modification of a polypropylene which is allowed to react with maleic anhydride and chlorine, and is, for example, produced by reacting chlorine and maleic anhydride upon a polypropylene, wherein either of the chlorine and the maleic anhydride may be reacted earlier upon the polypropylene. The reaction with chlorine is, for example, carried out by introducing a chlorine gas into a solution including a polypropylene. In addition, the reaction with maleic anhydride is, for example, carried out by reacting the maleic anhydride upon a polypropylene (or polypropylene chloride) in the presence of a peroxide.
(Acrylic Resin):
Because the above poly(propylene chloride) has a low level of coating film strength and weather resistance, the acrylic resin, which is included in the acrylic resin emulsion as used in the present invention, is a component to make up for this and to provide the beef tallow resistance and the solvent resistance along with the coating film strength and the weather resistance to the present invention aqueous coating composition.
The acrylic resin may be a pure acrylic resin as explained below, but may be a resin obtained by modifying a pure acrylic resin with the above poly(propylene chloride). The amount as modified is in the range of 0 to 30 weight %. In the case where the amount is more than this range the beef tallow resistance is inferior.
The pure acrylic resin is a resin obtained by homopolymerizing or copolymerizing acrylic monomers.such as (meth)acrylic acid, (meth)acrylic monomers containing a
Fritcher Jesse
Kim Juhan
Kozaki Mamoru
Makarewicz Jeffrey
Watanabe Takashi
Haugen Law Firm PLLP
Nutter Nathan M.
Toyota Technical Center U.S.A., Inc.
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