Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2000-09-15
2004-01-20
Berman, Susan W. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S084000, C522S085000, C522S086000, C522S088000, C522S146000, C522S148000, C522S170000, C522S172000, C522S181000, C524S588000, C524S837000, C524S800000, C524S732000, C524S612000
Reexamination Certificate
active
06680347
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
Photocurable coatings, known in the industry as UV curables, possess various characteristics which render their use highly desirable for applications requiring the formation of a coating. These characteristics include: (1) they are comprised of 100% reactive components which provide for environmentally acceptable coatings, (2) they are energy efficient requiring a small fraction of the energy normally consumed in thermally cured coating, (3) they can easily be formulated to meet a variety of applications since functionalized monomers and oligomers are available covering a wide range of properties, (4) the UV curing process in itself often imparts desirable properties to the cured coating, which cannot be achieved with thermally cured coatings and, (5) due to the wide range of viscosities inherent in the reactive monomers used in UV curable components, coating can be readily formulated to meet demanding viscosity requirements dictated by certain coatings applications.
There are two primary types of UV curable systems. The first proceeds by a free radical chain process in which low molecular weight monomers and oligomers are converted by absorption to UV radiation into highly-crosslinked, chemically-resistant films. The second type of UV curable system, which shows great promise for the future, polymerizes by a cationic mechanism and has the advantage of oxygen insensitivity compared to free-radical photocurable systems.
In general, cationic photocure systems are often deemed superior to free-radical photocuring processes for the following reasons: (a) they are readily sensitized by dyes and/or polycyclic aromatics, (b) they are insensitive to oxygen inhibitors, (c) they are terminated only by impurity quenching, and (d) they are characterized by an efficient post thermal cure.
One drawback associated with the use of cationic polymeric oligomers stems from their being poor film formers when used alone, i.e., they cure much more slowly than acrylate oligomers when irradiated with UV light. When they are blended with an appropriate reactive diluent, they form highly flexible films possessing desirable mechanical and physical properties. However, due to their slow cure rate, their use in quick-curing applications where time is of the essence, up to now, has been prohibited.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a process for making a self-dispersible, radiation curable coating composition involving:
(a) providing from about 10 to about 90% by weight of a cationic oligomer;
(b) providing from about 10 to about 90% by weight of an epoxy functional monomer;
(c) providing from about 0 to about 30% by weight of a surfactant component;
(d) providing from about 0 to about 10% by weight of a transfer agent;
(e) providing from about 1 to about 10% by weight of a photoinitiator, all weights being based on the weight of the composition; and
(f) mixing (a)-(e) to form the coating composition.
The present invention is also directed to a process for coating a substrate involving applying the above-disclosed radiation curable coating composition onto a surface of the substrate.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Not applicable.
DETAILED DESCRIPTION OF THE INVENTION
Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions are to be understood as being modified in all instances by the term “about”.
Cationic oligomers which may be employed by the present invention include epoxy oligomers, cycloaliphatic epoxy oligomers, vinyl ether oligomers, butyryl oligomers, unsaturated polyester oligomers and organosilicone oligomers.
Useful epoxy oligomers include those derived from glycidyl ethers of both polyhydric phenols and polyhydric alcohols, epoxidized fatty acids or drying oil acids, epoxidized diolefins, epoxidized di-unsaturated acid esters, as well as epoxidized unsaturated polyesters, preferably containing an average of more than one epoxide group per molecule. The preferred epoxy oligomers will have a molecular weight of from about 300 to about 600 and an epoxy equivalent weight of between about 150 and about 1,200. Representative examples of epoxy oligomers include condensation products of polyphenols and (methyl)epichlorohydrin. For the polyphenols, there may be listed bisphenol A, 2,2′-bis(4-hydroxyphenyl)methane (bisphenol F), halogenated bisphenol A, resorcinol, hydroquinone, catechol, tetrahydroxyphenylethane, phenol novolac, cresol novolac, bisphenol A novolac and bisphenol F novolac. There may also be listed epoxy compounds of the alcohol ether type obtainable from polyols such as alkylene glycols and polyalkylene glycols, e.g. ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerine, diglycerol, trimethylolpropane, pentaerythritol, inositol, sorbitol, polyethylene glycol, polypropylene glycol, polytetrahydrofuran, (i.e., poly(1,4-butanediol), which is obtainable under the designation TERATHONE® from DuPont), and alkylene oxide-adduct of bisphenols, and (methyl)epichlorohydrin; glycidyl amines obtainable from anilines such as diaminodiphenylmethane, diaminophenylsulfone and p-aminophenol, and (methyl)epichlorohydrin; glycidyl esters based on acid anhydrides such as phthalic anhydride and tetrahydro- or hexahydro-phthalic anhydride; and alicyclic epoxides such as 3,4-epoxy-6-methylcyclohexylmethyl and 3,4-epoxy-6-methylcyclohexyl carboxylate.
Glycidyl polyethers of polyhydric phenols are made from the reaction of a polyhydric phenol with epihalohydrin or glycerol dihalohydrin, and a sufficient amount of caustic alkali to combine with the halogen of the halohydrin. Glycidyl ethers of polyhydric alcohols are made by reacting at least about 2 moles of an epihalohydrin with 1 mole of a polyhydric alcohol such as ethylene glycol, pentaerythritol, etc., followed by dehydrohalogenation.
In addition to polyepoxides made from alcohols or phenols and an epihalohydrin, polyepoxides made by the known peracid methods are also suitable. Epoxides of unsaturated esters, polyesters, diolefins and the like can be prepared by reacting the unsaturated compound with a peracid. Preparation of polyepoxides by the peracid method is described in various periodicals and patents and such compounds as butadiene, ethyl linoleate, as well as di- or tri-unsaturated drying oils or drying oil acids, esters and polyesters can all be converted to polyepoxides. Epoxidized drying oils are also well known, these polyepoxides usually being prepared by reaction of a peracid such as peracetic acid or performic acid with the unsaturated drying oil according to U.S. Pat. No. 2,569,502.
In certain embodiments, the diepoxide is an epoxidized triglyceride containing unsaturated fatty acids. The epoxidized triglyceride may be produced by epoxidation of one or more triglycerides of vegetable or animal origin. The only requirement is that a substantial percentage of diepoxide compounds should be present. The starting materials may also contain saturated components. However, epoxides of fatty acid glycerol esters having an iodine value of 50 to 150 and preferably 85 to 115 are normally used. For example, epoxidized triglycerides containing 2% to 10% by weight of epoxide oxygen are suitable. The epoxide oxygen content can be established by using triglycerides with a relatively low iodine value as the starting material and thoroughly epoxidizing them or by using triglycerides with a high iodine value as starting material and only partly reacting them to epoxides. Products such as these can be produced from the following fats and oils (listed according to the ranking of their starting iodine value): beef tallow, palm oil, lard, castor oil, peanut oil, rapeseed oil and, preferably, cottonseed oil, soybean oil, train oil, sunflower oil, linseed oil. Examples of typical epoxidized oils are epoxidized soybean oil with an epoxide value of 5.8
Johnson Grannis S.
Saint Victor Marie-Esther
Berman Susan W.
Cognis Corporation
Drach John E.
Trzaska Steven J.
LandOfFree
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