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
1997-06-18
2002-03-19
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S449000, C525S451000, C525S532000, C525S922000
Reexamination Certificate
active
06359082
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for the preparation of epoxy(meth)acrylates which may be used as free radical curing binders for coating compositions, caulks and sealants and for the preparation of molded articles.
2. Description of the Prior Art
Epoxy(meth)acrylates, which are prepared by reaction of an epoxy resin, e.g., bisphenol-A-diglycidylether, with (meth)acrylic acid in the presence of catalysts are described, e.g., in DE-A 2,349,979. The epoxy(meth)acrylates are normally highly viscous substances, which are dissolved in low molecular weight monomers, such as hexane diol diacrylate, before undergoing further processing.
Modified epoxy(meth)acrylates have previously been prepared, e.g., by reaction with amines (DE-A 2,429,527) or dicarboxylic acids (DE-A 4,217,761), or by the reaction of the OH groups, which are produced during the addition of (meth)acrylic acid onto the epoxide group, with acid anhydrides (DE-A 4,109,048) or isocyanates (DE-A 3,519,117).
SUMMARY OF THE INVENTION
The present invention relates to a process for the preparation of epoxy(meth)acrylates by simultaneously reacting 1 equivalent of organic compounds containing epoxide groups with
A) 0.8 to 1.2 moles of organic dicarboxylic anhydrides having a molecular weight from 98 to 166 and
B) 0.8 to 1.2 OH equivalents of OH group-containing reaction products, which are prepared at a COOH/OH equivalent ratio of 0.6:1 to 0.95:1, of
a) (meth)acrylic acid and
b) tri- or tetrahydric ether alcohols having a number average molecular weight of 180 to 1000 and containing at least two ethylene and/or propylene oxide units as part of an ether structure.
DETAILED DESCRIPTION OF THE INVENTION
It could not have been predicted that it would be possible to react polyepoxides with dicarboxylic anhydrides and OH compounds to form epoxy(meth)acrylates, since polyepoxides are known to react with dicarboxylic anhydrides while undergoing cross-linking with one another. This reaction is utilized, e.g., for the preparation of molded articles.
Within the context of the present invention, “compounds having epoxide groups” mean organic compounds which have a number average molecular weight (M
n
) of 130 to 1000 and contain an average of at least one, preferably 1.5 to 6 and more preferably 1.5 to 2 epoxide groups per molecule. An “epoxide equivalent” means the amount of epoxide compounds in grams that contains one mole of epoxide groups.
Preferred compounds having epoxide groups are those having an epoxide equivalent weight of 100 to 500. Examples include polyglycidylethers of polyhydric phenols such as pyrocatechol, resorcinol, hydroquinone, 4,4′-dihydroxydiphenylmethane, 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A), 4,4′dihydroxydiphenylcyclohexane, 4,4′-dihydroxy-diphenylsulphone, tris-(4-hydroxyphenyl)-methane and novolaks (i.e., reaction products of mono- or polyhydric phenols with aldehydes, particularly formaldehyde, in the presence of acid catalysts). Polyglycidyl ethers of bisphenol A are preferred.
Also suitable are glycidyl ethers of monoalcohols such as n-butanol or 2-ethylhexanol; glycidyl ethers of polyhydric alcohols such as butane 1,4-diol, butene 1,4-diol, hexane 1,6-diol, glycerol, trimethylolpropane, pentaerythritol and polyethylene glycols; triglycidyl isocyanurate; polyglycidyl thioethers of polyhydric thiols such as bismercaptomethylbenzene; glycidyl esters of monocarboxylic acids such as versatic acid; and glycidyl esters of polyvalent, aromatic, aliphatic and cycloaliphatic carboxylic acids such as phthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, adipic acid diglycidyl ester and hexahydrophthalic acid diglycidyl ester.
Dicarboxylic anhydrides A) are selected from saturated, aromatic or unsaturated (cyclo)aliphatic dicarboxylic anhydrides having 4 to 9 carbon atoms such as the anhydrides of maleic acid, succinic acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid or norbornene dicarboxylic acid.
Component B) is selected from OH group-containing reaction products (meth)acrylic acid with tri- or tetrahydric ether alcohols having a number average molecular weight (determined by end group analysis) of 180 to 1000 and containing at least two ethylene and/or propylene oxide units as part of an ether structure. These reaction products are prepared at a COOH/OH equivalent ratio of 0.6:1 to 0.95:1, preferably 0.65:1 to 0.90:1. The ether alcohols are obtained by the alkoxylation of suitable starter molecules in known manner. Preferred starter molecules are ether group-free tri- or tetrahydric alcohols, which correspond to the ether alcohols. Examples include glycerol, trimethylolpropane, trimethylolethane, pentaerythritol and mixtures thereof. The ether alcohols preferably have a degree of alkoxylation of 2 to 20, more preferably 2 to 15. The degree of alkoxylation refers to the average number of moles of ethylene oxide and/or propylene oxide which have been added onto 1 mole of an alcohol used as starter molecule.
The reaction between the components a) and b) takes place according to known methods, e.g., by azeotropic esterification of (meth)acrylic acid with the ether alcohols.
The reaction of the epoxides with compounds A) and B) takes place in one step, for example, according to the processes of DE-OS 2,429,527 and DE-A 2,534,012 (which correspond to U.S. Pat. Nos. 4,253,198 and 4,081,492, respectively, both of which are herein incorporated by reference), optionally in the presence of solvent. Suitable solvents include inert solvents such as butyl acetate, toluene, cyclohexane and mixtures thereof, and also copolymerizable monomers such as those described below. Preferably, no solvents or monomers are used.
The reaction is generally carried out in the presence of about 0.01 to 3 wt. %, based on the epoxide, of catalysts such as tertiary amines, quaternary ammonium salts, alkali hydroxides, alkali salts of organic carboxylic acids, mercaptans, dialkyl sulphides, sulphonium or phosphonium compounds and phosphines. The use of quaternary ammonium salts such as triethylbenzylammonium chloride is particularly preferred. The reaction takes place at 20 to 120° C., preferably 40 to 90° C.
The epoxy(meth)acrylates may optionally be modified with basic nitrogen compounds in a amount sufficient to provide up to 0.3 NH equivalents per epoxide equivalent. The modification reaction may be carried out before or after the epoxide reaction with components A) and B). Suitable basic nitrogen compounds include ammonia, (cyclo)aliphatic primary or secondary mono- or polyamines, preferably having a molecular weight of 31 to 300.
Examples of primary amines include mono- and diamines such as methylamine, n-butylamine, n-hexylamine, 2-ethylhexylamine, cyclohexylamine, ethanolamine, benzylamine, ethylene diamine, the isomeric diaminobutanes, the isomeric diaminohexanes and 1,4-diaminocyclohexane.
Examples of secondary amines include dimethylamine, diethylamine, diethanolamine, diisopropanolamine, N-methylethanolamine and N-cyclohexylisopropylamine.
The reaction of the epoxide groups with the nitrogen compounds may optionally take place in the presence solvents such as those previously set forth. The reaction is preferably carried out in the absence of solvent. The reaction temperature is 20 to 120° C., preferably 40 to 90° C.
The quantities of starting compounds are chosen such that,the reaction leads to essentially complete conversion of the epoxide groups originally present.
In order to protect the polymerizable reaction products according to the invention from unwanted premature polymerization, it is advisable to add, during the preparation process, 0.001 to 0.2 wt. %, based on the total reaction mixture including auxiliaries and additives, of polymerization inhibitors or antioxidants, such as phenols and phenol derivatives, preferably sterically hindered phenols. Other suitable stabilizers are described in “Methodender organischen Chemie” (Ho
Bayer Aktiengesellschaft
Eyl Diderico van
Gil Joseph C.
Roy Thomas W.
Sellers Robert E. L.
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