Cleaning and liquid contact with solids – Processes – Paints – varnishes – lacquers – or enamels – removal
Reexamination Certificate
1998-02-12
2001-06-26
Gulakowski, Randy (Department: 1746)
Cleaning and liquid contact with solids
Processes
Paints, varnishes, lacquers, or enamels, removal
C510S201000
Reexamination Certificate
active
06250317
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to films and methods for the removal of applied films.
2. Description of Related Art
At present, the development of coating materials that cause little or no environmental pollution and promise to conserve energy has been advancing to a large extent. In recent years, a great need has arisen for suitable methods for recovering and putting to reuse (recycling) articles that are coated with an applied film. When these coated articles are to be actually recovered and reused, however, difficulty is often encountered in removing the applied films from the coated articles, thus posing a serious obstacle. Particularly, substances such as plastics tend to aggravate the difficulty incurred in recovering and reusing the coated articles because they generally cannot be heated. However, in the case of an applied film which is intended to provide temporary protection for a coated article during fabrication, it is often preferable that the applied film be capable of being removed from the coated article with simplicity.
The resin for forming an applied film is generally a macromolecular substance which is capable of enabling the applied film to manifest superior and/or perfect film properties. Often, the applied film is in a cross-linked state. It is extremely difficult to remove this applied film simply using an organic solvent. This fact constitutes a serious hindrance to recovering and reusing the coated article. For the applied film to be easily removed, it might be thought that it would suffice to incorporate an easily severable bond into the applied film. However, a bond which is easily separable may possess inferior weatherability and, therefore, often proves to be unfit for a binder of a coating material.
SUMMARY OF THE INVENTION
The present inventor has pursued a diligent study with a view to solving the various defects suffered by the prior art as described above. As a result, the inventor found an applied film formed of a resin comprising a compound or unit represented by the following formula
excels in waterproofness and lightfastness, and also decomposes upon contact with an acid and water.
The present invention is therefore directed to films and methods for the removal of a film applied to an article, the film being formed of a resin containing a unit represented by the following formula
The method comprising contacting the film with a mixture (A) comprising (a) an acidic compound and (b) water.
Additional objects, features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The present invention also includes the use of mixtures (A) that contain (c) an organic solvent. The resin containing a chemical structure represented by the chemical structural formula (1) can be produced, for example, by a reaction of a carbonyl group-containing compound with a hydrazide group-containing compound. In addition, the applied film may optionally be a cross-linked applied film.
The applied film to be used in the method of this invention is subject to no particular restriction except for the requirement that the resin forming the applied film contain a chemical structure or compound represented by the chemical structure formula (1) mentioned above. Concrete examples of the applied film include an applied film which is formed by cross-linking a carbonyl group-containing resin with a polyhydrazide compound or a polysemicarbazide compound and an applied film which is formed by cross-linking a polyhydrazide-containing resin or a polysemicarbazide-containing resin with a carbonyl group-containing compound which have been reported in numerous articles of literature [for example,
The Chemistry of Amides, Part Two,
published by Interscience Publishers in 1970, Chapter 10, pp. 515-600 which is incorporated herein by reference].
The acidic compound (a) to be used in the mixture (A) by the method of this invention is generally intended as a catalyst for a hydrolytic reaction of a compound of formula (1) mentioned above. The acidic compound (a) is not subject to any particular restriction and, for effective use herein, may be, for example, either an inorganic acid or an organic acid. It should, however, preferably be an organic acid that would be readily soluble in the mixture (A), depending on the composition of (A). The power with which the acidic compound decomposes the applied film increases in proportion as the compound gains in acidity. As concrete examples of the acidic compound (a), monobasic acids, dibasic acid, polybasic acid, and inorganic acids may be cited.
Suitable monobasic acids include aromatic monobasic acids such as toluene sulfonic acid, benzoic acid, methylbenzoic acid, and p-t-butylbenzoic acid; saturated or unsaturated fatty acids of 1-24 carbon atoms such as formic acid, acetic acid, lactic acid, propionic acid, butyric acid, caproic acid, caprylic acid, peralgonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, cyclohexane carboxylic acid, 9-decenoic acid, oleic acid, eleostearic acid, eraidic acid, brassylic acid, linolic acid, and linoleic acid; and hydroxyl carboxylic acids (oxy acids) such as dimethyl propionic acid, oxypivalic acid, 12-hydroxydodecanoic acid, 12-hydroxystearic acid, ricinolic acid, paraoxybenzoic acid, salicylic acid, and 4,4-bis (4′-hydroxyphenyl) pentanoic acid, for example. Lower alkyl esters and glycerides of these monobasic acids and such cyclic ester compounds as &egr;-caprolactone, &ggr;-valerolactone, and other lactones are also usable as monobasic acids.
Concrete examples of the dibasic acid include aromatic dicarboxylic acids and anhydrides thereof such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, 4,4′-biphenyl dicarboxylic acid, and diphenyl methane-4,4′-dicarboxylic acid; alicyclic dicarboxylic acids and anhydrides thereof such as hexahydroisophthalic acid, hexahydroterephthalic acid, hexahydrophthalic acid, and tetrahydrophthalic acid; aliphatic dicarboxylic acids and anhydrides thereof such as adipic acid, sebacic acid, suberic acid, succinic acid, glutaric acid, maleic acid, chloromaleic acid, fumaric acid, dodecanoic diacid, pimelic acid, azelaic acid, itaconic acid, citraconic acid, and dimeric acid; and lower alkyl esters such as methyl esters and ethyl esters of these dicarboxylic acids.
Concrete examples of the polybasic acid include aromatic polybasic acids and anhydrides thereof such as phthalic acid, isophthalic acid, terephthalic acid, 4,4′-biphenyl dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, tetrachlorophthalic acid, 4,4′-diphenyl methane dicarboxylic acid, trimellitic acid, trimesic acid, and pyromellitic acid; saturated and unsaturated polybasic acids and anhydrides thereof such as succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecane dicarboxylic acid, suberic acid, pimelic acid, maleic acid, fumaric acid, itaconic acid, brassylic acid, and citraconic acid; alicyclic polybasic acids and anhydrides thereof such as hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, hexahydrotrimellitic acid, methyl hexahydro-phthalic acid, methyl hydroterephthalic acid, &Dgr;1-tetrahydrophthalic acid, &Dgr;2-tetrahydrophthalic acid, &Dgr;3-tetrahydrophthalic acid, &Dgr;4-tetrahydrophthalic acid, &Dgr;1-tetrahydroisophthalic acid, &Dgr;2-tetrahydroisophthalic acid, &Dgr;3-tetrahydroisophthalic acid, &Dgr;4-tetrahydroisophthalic acid, &Dgr;1-tetrahydroterephthalic acid, &Dgr;2-tetrahydroterephthalic acid, methyl tetrahydrophthalic acid, endomethylene tetrahydrophthalic acid, and methylendomethylene tetrahydrophthalic acid; hexachloroendomethyl
Gulakowski Randy
Kansai Paint Co. Ltd
Rader Fishman & Grauer
Wilkins Yolanda E.
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