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
2001-11-16
2003-09-02
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...
C525S524000, C525S526000, C525S527000, C525S528000, C525S529000, C525S533000, C528S087000, C528S099000, C528S102000, C528S112000, C549S522000, C549S555000
Reexamination Certificate
active
06613849
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns hydroxyaliphatic functional diglycidyl ethers of bisphenols (epoxy resins); curable (thermosettable) mixtures of at least one hydroxyaliphatic functional epoxy resin and at least one curing agent and/or catalyst therefor, as well as cured (thermoset) compositions prepared therefrom; and derivatives prepared therefrom. The bisphenol precursor to the diglycidyl ether contains a hydroxyaliphatic group linkage between the two aromatic rings of the bisphenol.
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention provides novel hydroxyaliphatic epoxy resins, curable mixtures of at least one hydroxyaliphatic functional epoxy resin and at least one curing agent and/or catalyst therefor, as well as the cured (thermoset) compositions prepared therefrom. Epoxy resins are well established as a class of curable compositions which find efficacy in a myriad of applications. The curing of epoxy resins is effected by a wide range of curing agents including, for example, the primary and secondary aliphatic, cycloaliphatic and aromatic polyamines; dicarboxylic acids and the anhydrides thereof; aromatic hydroxyl containing compounds; imidazoles; guanidines; urea-aldehyde resins and alkoxylated derivatives thereof; melamine-aldehyde resins and alkoxylated derivatives thereof; amidoamines; epoxy resin adducts; and various combinations thereof. In addition to said curing agents, one or more catalysts, such as a quaternary ammonium or phosphonium salts are frequently added to accelerate the cure rate as well as to insure completeness of the cure. While the curing of epoxy resins may be effected via the usual epoxy resin curing agents and catalysts, a number of additional factors are critical to and interrelate to the curing process for epoxy resins. These factors include the processing time and temperature profile employed, the epoxide equivalent weight (EEW) of the epoxy resin component(s) employed, the active hydrogen equivalent weight of the curing agent component(s) employed, the final configuration of the curable mixture, and other such variables and combinations of variables. For many of the applications served by epoxy resins, it would be desirable to possess controlled higher reactivity during the curing process, while maintaining, or even improving one or more of the physical and/or mechanical and/or thermal properties of the cured products thereof. The hydroxyaliphatic epoxy resins of the present invention impart controlled higher reactivity during the curing process, while using a wide variety of conventional curing agents and/or catalysts.
The hydroxyaliphatic epoxy resins of the present invention possess a unique molecular structure heretofore unavailable in an epoxy resin. The key feature of the molecular structure inherent to the hydroxyaliphatic epoxy resins of the present invention is the presence of the hydroxy group attached to the aliphatic linkage between the two aromatic rings each bearing a glycidyloxy group. The hydroxy group inherent to the hydroxyaliphatic epoxy resins of the present invention provides curable epoxy resin compositions, with outstanding processability through acceleration of the cure and cured epoxy resin compositions thereof, with substantial improvements in one or more physical and/or mechanical and/or thermal properties. A specific mechanical property expected to be improved by the presence of the aliphatic hydroxy group is adhesion. Furthermore, this improvement is expected, without significantly diminishing the glass transition temperature of the cured epoxy resin. One conventional method for incorporation of aliphatic hydroxy groups into an epoxy resin specifically used to promote adhesion involves partial hydrolysis of epoxide groups to &agr;-glycol groups. However, this markedly lowers the glass transition temperature of the cured epoxy resin by removal of available epoxide groups for reaction with curing agent (lowers the crosslink density). The second conventional method for the incorporation of aliphatic hydroxy groups into an epoxy resin involves advancement of the epoxy resin to produce secondary aliphatic hydroxy groups. This again markedly lowers the glass transition temperature of the cured epoxy resin by forming highly flexible linkages (for example, diether linkages if a diphenol is used in the advancement reaction) between aromatic ring pairs.
Additionally, the hydroxy group inherent to the hydroxyaliphatic epoxy resins of the present invention is present in an exact and defined stoichiometry and thus serves as a convenient reactive site for conversion to a myriad of other functional moieties, thus providing additional epoxy resin compositions of the present invention. Thus, for example, esterification of the hydroxy group with an ethylenically unsaturated carboxylic acid halide, provides a novel thermosettable composition containing both diglycidyl ether and polymerizable ethylenic unsaturation. The resulting diglycidyl ether containing a polymerizable ethylenic unsaturation may be further reacted with an ethylenically unsaturated monocarboxylic acid, such as methacrylic acid, to provide vinyl ester resins containing three or four polymerizable ethylenically unsaturated groups. These novel vinyl ester resins may be thermoset to provide highly crosslinked products. The diglycidyl ether compositions of the present invention containing polymerizable ethylenic unsaturation may be further converted to a polymer modified epoxy resin, via copolymerization with one or more ethylenically unsaturated monomers. Reaction of a polymer modified epoxy resin with an ethylenically unsaturated monocarboxylic acid provides the polymer modified vinyl ester resins of the present invention.
As a further embodiment of the present invention, coupling of a pair of the hydroxyaliphatic epoxy resin molecules, for example via esterification with a diacid halide or, via reaction with a diisocyanate, provides novel tetraglycidyl ethers which can be thermoset to highly crosslinked products. These tetraglycidyl esters may be further reacted with ethylenically unsaturated monocarboxylic acid, such as acrylic acid or methacrylic acid, to provide vinyl ester resins containing four polymerizable ethylenically unsaturated groups. Such polyfunctional vinyl esters are thermosettable to provide highly crosslinked products.
One aspect of the present invention pertains to hydroxyaliphatic epoxy resins or vinyl ester resins represented by the following Formula I
wherein each R is independently hydrogen or a hydrocarbyl or hydrocarbyloxy group having from one to about 10, preferably one to about 4, carbon atoms, a halogen atom, preferably chlorine, bromine or fluorine, a nitro group, a nitrile group or a —CO—R
2
group; E is a
group; each R
1
is independently hydrogen or a hydrocarbyl group having from one to about 10, preferably one to about 6, carbon atoms; X is a
group, each R
2
is independently hydrogen or a hydrocarbyl group having from one to about 10, preferably one to about 2, carbon atoms; R
3
is a hydrocarbyl group having from one to about 10, preferably one to about 2, carbon atoms; n has a value of from one to about 10, preferably one to about 2.
A further aspect of the present invention pertains to advanced epoxy resins prepared using (A) one or more hydroxyaliphatic epoxy resins, optionally, (B) one or more epoxy resins, and (C) one or more compounds having an average of more than one hydrogen atom per molecule which is reactive with an epoxide group.
Another aspect of the present invention pertains to curable (thermosettable) compositions comprising (A) one or more hydroxyaliphatic epoxy resins, advanced hydroxyaliphatic epoxy resins, or a mixture thereof; optionally, (B) one or more epoxy resins; and (C) a curing amount of one or more curing agents and/or catalysts therefor.
A further aspect of the present invention pertains to products resulting from curing the aforementioned curable compositions.
Another aspect of the present invention pertains to curable (thermosettable) compositions comprising (
Clement Katherine S.
Hefner, Jr. Robert E.
Walker Louis L.
Sellers Robert E. L.
The Dow Chemical Company
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