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
2002-05-20
2004-07-06
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...
C002S161700, C427S002300, C428S035200, C428S500000, C428S532000, C524S035000, C524S043000, C524S045000, C524S046000, C524S047000, C524S052000, C524S507000, C524S512000, C524S514000, C524S515000
Reexamination Certificate
active
06759473
ABSTRACT:
TECHNICAL FIELD
This invention relates to a coating agent and a coated article. More particularly, it relates to a coating agent giving a coated article by coating a dip-formed article such as a glove with the coating agent, which coated article can be easily donned and put off, from which fine particles are not easily released and which has an enhanced anti-blocking property; and to a coated article made by coating a dip-formed article with the coating agent.
BACKGROUND ART
Dip-formed articles made from natural rubber latex or synthetic rubber latex are used, for example, as rubber gloves and finger cots. In general the skin-contacting inner surface of a rubber glove is sticky and not slippery, and the rubber glove cannot be easily donned and put off. To facilitate donning and putting off of the rubber glove, various methods have been proposed. For example, to enhance the anti-sticking property, a method of applying a dusting powder such as talc powder onto the inner surface of a glove, and a method of subjecting the inner surface of a glove to a chlorinating treatment to form protrusions on the inner surface. However, in the former method, the applied dusting powder is easily released upon donning and putting off the glove, and, when the glove is used in a medical field including surgery, the released dusting powder may contaminate an operated part and cause postoperative complications. In the latter method, the treating cost is high, the facilitation of donning and putting off cannot be enhanced to the desired extent, and the use of chlorine may cause environmental pollution.
Further, proposals of enhancing donning and putting-off properties of a glove have been made wherein an elastomer layer or a resin layer, which contains fine particles incorporated therein, is formed on the inner surface of a glove. For example, a medical rubber glove has been proposed in Japanese Examined Patent Publication No. S60-6655 (U.S. Pat. No. 4,070,713), which has an inner lubricating layer formed from a latex of carboxylated styrene-butadiene rubber having starch dispersed therein. A rubber glove has been proposed in Japanese Unexamined Patent Publication (hereinafter abbreviated to “JP-A”) No. H11-61527, which has an inner lubricating resin layer formed from an aqueous dispersion comprising a synthetic rubber latex and an organic filler, which rubber latex is incapable of being coagulated with a coagulant contained in a main rubber layer of the rubber glove. These proposals provide an improvement in the donning and putting-off properties to some extent, but, the surfaces of fine particles as lubricant are partly covered with a rubber latex. Thus, the improvement in donning and putting-off properties achieved is still not to the desired extent, and the inner lubricating layer tends to stick to each other and the sticking parts are difficult to separate.
A rubber glove has been proposed in JP-A H8-294930 which is made by forming on a glove form a covering resin layer from a rubber latex formulation comprising, as the principal ingredients, fine thermoplastic resin particles, a rubber latex, and a blocked isocyanate. By the use of a blocked isocyanate, adhesion of the thermoplastic resin particles to an elastomer layer formed from the rubber latex is enhanced, but, the improvement in the donning and putting-off properties is still not to the desired extent. Further, adhesion of the covering resin layer to a main rubber layer is poor, and thus, the covering resin layer tends to be separated from the main rubber layer, and pliability of the glove is liable to deteriorate due to the elastomer crosslinked with the blocked isocyanate.
DISCLOSURE OF THE INVENTION
In view of the foregoing prior art, a primary object of the present invention is to provide a dip-formed article such as, for example, a rubber glove, which can easily be donned and put off, and wherein fine particles and an elastomer ingredient not released, or are released only to a very slight extent, when the glove is donned or put off, or during wearing, and the inner elastomer coating layer exhibits an enhanced anti-blocking property; and to provide a coating agent used for the dip-formed article.
The present inventors made extensive research to achieve the above-mentioned object, and found that the aimed coated article is obtained by coating a dip-formed article with a coating agent comprising a polymer latex having incorporated there in a special dispersion stabilizer. Based on this finding, the present invention has been completed.
In accordance with the present invention, there is provided a coating agent comprising a polymer latex dispersion-stabilized with a water-soluble high-molecular weight compound having an alcoholic hydroxyl group. Preferably the coating agent further comprises fine particles.
In accordance with the present invention, there is further provided a coated article made by coating a dip-formed article with the above-mentioned coating agent.
BEST MODE FOR CARRYING OUT THE INVENTION
The polymer latex which can be used in the coating agent of the present invention is a polymer latex dispersion-stabilized with a water-soluble high-molecular weight compound having an alcoholic hydroxyl group (which compound is hereinafter referred to as “hydroxyl group-containing water-soluble polymer” when appropriate).
As specific examples of the hydroxyl group-containing water-soluble polymer, there can be mentioned vinyl alcohol polymers such as polyvinyl alcohol and various modified products thereof; alkali-soluble polymers having an alcoholic hydroxyl group; cellulose derivatives such as alkyl celluloses, hydroxyalkyl celluloses, alkylhydroxyalkyl celluloses and carboxymethyl cellulose; starch derivatives such as alkyl starches, carboxymethyl starch and oxidized starch; arabian gum and tragacanth gum; and polyalkylene glycols. Of these, vinyl alcohol polymers and alkali-soluble polymers having an alcoholic hydroxyl group are preferable because industrially quality-stabilized products thereof are easily available. Vinyl alcohol polymers are especially preferable because their coating layers have excellent water-resistance.
The hydroxyl group-containing water-soluble polymer preferably has a molecular weight (weight average molecular weight) of at least 2,000. When the molecular weight is smaller than 2,000, the dispersion-stabilizing effect is reduced.
The vinyl alcohol polymers are those which have vinyl alcohol units, are substantially soluble in water and, when they are used in polymerization, are capable of forming a stable polymer latex. Such vinyl alcohol polymers can easily be made by, for example, a process wherein a vinyl ester polymer is prepared by polymerizing a vinyl monomer composition comprising a vinyl ester monomer or monomers as principal ingredient by a publicly known procedure (namely, a homopolymer of a vinyl ester monomer, a copolymer of at least two kinds of vinyl ester monomers or a copolymer of a vinyl ester monomer with other ethylenically unsaturated monomer is prepared), and then, the vinyl ester polymer is saponified by an ordinary procedure. Vinyl alcohol polymers having a modifying group such as a mercapto group having introduced to their side chains or at terminals can also be used.
The vinyl ester monomers can be used provided that they are capable of being radically polymerized, and, as specific examples thereof, there can be mentioned vinyl formate, vinyl acetate, vinyl propionate, isopropenyl acetate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate and vinyl pivalate. Of these, vinyl acetate is preferable because it is industrially less costly produced.
As specific examples of the monomer copolymerizable with the vinyl ester monomer, there can be mentioned olefins such as ethylene, propylene, 1-butene and isobutene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride and itaconic anhydride; acrylic acid esters such as methyl acry
Inoue Toshihiro
Nakamura Misao
Armstrong Kratz Quintos Hanson & Brooks, LLP
Reddick Judy M.
Zeon Corporation
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