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
2000-06-12
2003-09-23
Shosho, Callie (Department: 1714)
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...
C524S519000, C524S523000, C524S527000, C525S221000, C525S222000, C525S239000, C525S214000, C525S330700
Reexamination Certificate
active
06624234
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Technical Field
The present invention relates to an aqueous coating composition for automotive upholstery, which has excellent coatability to plastic materials, particularly, polyolefin materials.
B. Background Art
As to plastic materials utilized for automotive upholstery, various ones are selected from among such as polypropylene (PP), acrylonitrile-styrene (AS), acrylonitrile-butadiene-styrene (ABS), poly(phenylene oxide) (PPO), poly(vinyl chloride) (PVC), polyurethane (PU) and polycarbonate (PC) in accordance with physical properties demanded to product specifications. In recent years, however, polyolefin materials having excellent recyclability are getting often used in view of environmental protection.
Coatings suitable for upholstery are applied to these plastic materials. However, it is difficult to make the resultant coating films adhere to the polyolefin materials, because the polyolefin materials have low surface activity and are crystalline.
Therefore, a pretreatment to ensure the adhesion, such as plasma treatment and flame treatment, is made. Consequently, the coating process becomes complicated, and this pretreatment is a cause of an increase in costs.
In addition, in order to improve the coatability to the polyolefin, a coating composition is generally allowed to contain a poly(olefin chloride) resin to be a solvent type coating composition in which the poly(olefin chloride) resin is dissolved in an organic solvent. However, when such a solvent type coating composition is stored or handled, not only are there problems of environmental deterioration (such as destruction of ozone layer and occurrence of photochemical smog), but also there are anxieties about occurrence of fires and bad influence upon human bodies, because the solvent easily volatilizes.
Chemical resistance such as engine oil resistance and grease resistance will be demanded to automotive uses.
SUMMARY OF THE INVENTION
A. Object of the Invention
An object of the present invention is to provide a coating composition for automotive upholstery, with which a 1-coat finish of not yet surface-treated (pretreated) plastic materials such as polyolefin materials can be performed, and which is aqueous, and excellent also in chemical resistance.
B. Disclosure of the Invention
The present inventors made various experiments to solve the above-mentioned problems. As a result, they completed the present invention by verifying that, if an emulsion type is used as the poly(olefin chloride) resin, and if the chlorination degree thereof is adjusted to a specific ratio, and if this poly(olefin chloride) resin is combined with a large amount of emulsion of a pure acrylic resin within the specific ratio range, then the use of the organic solvent can be omitted or diminished, and further, the 1-coat finish of the plastic materials such as polyolefin materials can be performed, and the chemical resistance can also be enhanced.
That is to say, an aqueous coating composition for automotive upholstery, according to the present invention, comprises a resin emulsion as an essential component, wherein the resin emulsion includes poly(olefin chloride) resin emulsion A and pure acrylic resin emulsion B in a weight ratio (A/B) of 25/75~30/70 in terms of solid content, wherein poly(olefin chloride) resin emulsion A is an emulsion of a poly(olefin chloride) resin having a chlorine content of 22~25 wt % in terms of solid content and a weight-average molecular weight of 60,000~80,000, and wherein pure acrylic resin emulsion B is an emulsion of a pure acrylic resin having a glass transition temperature of not lower than 40° C.
When the above aqueous coating composition for automotive upholstery, according to the present invention, is a lacquer paint, it is preferable that the composition further comprises a scaly inorganic powder in a ratio of 60~75 parts by weight per 100 parts by weight of the resin emulsion in terms of solid content.
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
(Aqueous Coating Composition)
The aqueous coating composition for automotive upholstery, according to the present invention, comprises a resin emulsion as an essential component, wherein the resin emulsion includes poly(olefin chloride) resin emulsion A and pure acrylic resin emulsion B. The total ratio of these two kinds of resin emulsions is preferably in the range of 15~30 wt %, in terms of solid content, of the entirety of the coating composition.
In the present invention, usually, the poly(olefin chloride) resin and the pure acrylic resin are emulsified separately from each other, and then mixed together.
As to the above resin emulsion, the poly(olefin chloride) resin or pure acrylic resin is particulately dispersed in an aqueous medium, and the particle surfaces thereof are stabilized with such as emulsifiers, surfactants, or dispersants.
(Poly(olefin chloride) resin)
The poly(olefin chloride) resin gives the coating composition sufficient coatability to polyolefin materials, because the polyolefin has affinity for plastic materials to be coated therewith, particularly, polyolefin materials, and further because the polyolefin is polarized by chlorination to enhance its film formability.
Examples of the polyolefin include: homopolymers of such as ethylene and propylene; random copolymers or block copolymers obtained by copolymerizing two or more monomers such as olefin monomers (e.g. ethylene, propylene, 1-butene, 1-pentene, 1-heptene and 1-octene) and vinyl monomers having a terminal vinyl group (e.g. vinyl alkyl ethers, vinyl chloride and vinyl acetate); hydrogenated products from copolymers of such as styrene, butadiene, isoprene and dicyclopentadiene. These may be used either alone respectively or in combinations with each other. Although not especially limited, polypropylene is preferable because it is easily available and has high adhesion.
It is necessary that the poly(olefin chloride) has a weight-average molecular weight in the range of 60,000~80,000. In the case where the weight-average molecular weight is less than the above range, swelling with engine oil easily occurs, therefore the engine oil resistance is low. In the case where the weight-average molecular weight is more than the above range, the viscosity becomes high in the emulsifying step, therefore the emulsification is difficult, and further, the storage stability is also bad.
It is necessary that the poly(olefin chloride) has a chlorine content of 22~25 wt % in terms of solid content. In the case where the chlorine content is less than the above range, the affinity and the compatibility between the poly(olefin chloride) and the pure acrylic resin are both so poor that it is difficult to obtain a uniform coating film. On the other hand, in the case where the chlorine content is more than the above range, the adhesion to polyolefin materials is inferior.
In the present invention, the poly(olefin chloride) may be modified (grafted) with an unsaturated polycarboxylic acid and/or an acid anhydride thereof, because the compatibility between the poly(olefin chloride) and the pure acrylic resin is thereby improved to enhance the water dispersibility. If the poly(olefin chloride) is modified with the acid anhydride and/or carboxylic acid, then the acid anhydride group and/or carboxyl group thereof is in the form of a free radical and/or reacts with a basic substance to form a carboxylate anion, with the result that the water solubility is displayed. Therefore, the modified poly(olefin chloride) is easily emulsified and has high water dispersibility. As a result, the storage stability of the aqueous coating composition is enhanced.
Examples of the unsaturated acid anhydride and/or carboxylic acid include maleic acid, fumaric acid, maleic anhydride, citraconic acid, citraconic anhydride, itaconic acid and itaconic anhydride. These may be used either alone respectively or in combinations with each other. Although not especially limited
Ishimoda Yukiko
Itakura Tatsuya
Itoh Sukekuni
Kawano Shinnosuke
Watanabe Takashi
Haugen Law Firm PLLP
Honda Giken Kyogo Kabushiki Kaisha
Shosho Callie
LandOfFree
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