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
1995-12-18
2002-12-03
Gulakowski, Randy (Department: 1746)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S423000, C525S524000, C525S532000, C525S533000, C525S540000, C528S093000, C528S103000, C528S103500, C528S111000, C528S111300, C528S111500, C528S113000, C428S413000
Reexamination Certificate
active
06489405
ABSTRACT:
The present invention relates to a curable epoxy resin formulation containing specific long-chain epoxy group-terminated polysters and polyalkylene di- and triamines, and to the use thereof for encapsulating electrical and electronic components.
Curable epoxy resin formulations which may be used as casting resin materials for encapsulating electrical and electronic components are known in the art. Exacting demands are made of such encapsulating materials, in particular with respect to heat ageing and to flexibility at different temperatures.
In U.S. Pat. No. 3,299,169 there is disclosed a flexible epoxy resin formulation in which the diglycidyl ether of a diphenol is modified with a diglycidyl ether of a polyalkylene glycol, and a low molecular weight polyoxyalkylenediamine is used as hardener. The mouldings fabricated from such epoxy resin formulations have only comparatively low flexibility.
In U.S. Pat. No. 3,929,717 there is likewise disclosed an encapsulating formulation consisting of a diglycidyl ether of a diphenol, a diglycidyl ether of a polyalkylene glycol and a polyoxyalkylenediamine, which formulation additionally comprises primary or secondary aryl- or alkanolamines for enhancing the solubility of the encapsulating formulation in alcohol. The mouldings obtained from these epoxy resin formulations are of comparatively low flexibility.
In U.S. Pat. No. 4,866,108 there are disclosed adhesive formualtions based on the diglycidyl ester of dimerised linoleic acid and an adduct of 2 mol of the diglycidyl ether of bisphenol A and 1 mol of dimerised linoleic acid, and which additionally comprise plasticisers. In these formulations polyesters based on linoleic acid are neither used nor in any way made obvious to those skilled in the art.
It has now been found that it is possible to obtain flexible mouldings which are based on modified epoxy resins and which retain their flexibility over a wide temperature range, especially at low temperatures, and which also meet exacting demands made of ageing resistance, by using as epoxy resin an epoxy group-terminated polyester of a dimerised or trimerised fatty acid and a polyhydric alcohol and, as hardener for the epoxy resin, a mixture of a polyoxyalkylene di- or triamine and a hardener which is not a polyoxyalkyleneamine.
Accordingly, the invention relates to a curable epoxy resin formulation which comprises
a) 40 to 100% by weight of an epoxy group-terminated polyester of a dimerised or trimerised fatty acid and a polyhydric alcohol, and 0 to 60% by weight of a diepoxide which is not an epoxy group-terminated polyester,
b) a hardener for epoxy resins consisting of 50 to 99% by weight of a polyoxyalkylene di- or triamine and 1 to 50% by weight of a hardener which is not a polyoxyalkyleneamine, and comprising as further optional components
c) a curing accelerator, and
d) customary modifiers for epoxy casting resins, with the proviso that the sum of the constituents in component a) as well as in component b) is in each case 100% by weight.
Component a) of the novel epoxy resin formulations constitutes a known class of compounds and embraces the adducts of diepoxides with carboxyl-terminated polyesters. Such adducts based on diglycidyl compounds and carboxyl-terminated polyesters of dimerised monomeric unsaturated fatty acid and alkane diols and the preparation thereof are disclosed, inter alia, in U.S. Pat. No. 3,816,365. Epoxy group-containing adducts of cycloaliphatic diepoxides which contain at least one one 1,2-epoxy group located at a 5- or 6-membered carbocyclic ring, typically bis(2,3-epoxycyclopentyl) ether, 2,3-epoxy-cyclopentylglycidyl ether, 1,2-bis(2,3-epoxycyclopentyloxy)ethane or 3,4-epoxy-cyclohexylmethyl-3′, 4′-epoxycyclohexanecarboxylate, and the carboxyl-terminated polyesters of dimerised monomeric unsaturated fatty acid and alkanediols, as well as the preparation thereof, are more fully disclosed in U.S. Pat. No. 3,642,674. These epoxy group-containing adducts may usually be prepared by reacting 1 mol of the carboxyl group-terminated polyester with 2 mol of the diepoxide at elevated temperature.
Component a) of the the epoxy resin formulations of this invention is preferably an epoxy group-containing adduct of a diglycidyl compound and a carboxyl-terminated polyester of formula I
wherein
R
1
is the hydrocarbon radical of an unsaturated or a saturated aliphatic-cycloaliphatic dicarboxylic acid obtained by dimerisation of an unsaturated monomeric fatty acid containing 14 to 24, preferably 16 to 18, carbon atoms, in the molecule, and optional subsequent hydrogenation of such a dimerised fatty acid,
A is a straight-chain or branched alkylene radical of 2 to 18 carbon atoms,
z is 1 or 2, and
n is an integer from 1 to 20, preferably from 2 to 6.
Diglycidyl compounds suitable for the preparation of the epoxy group-containing adducts are the standard epoxy resins of epoxy resin technology. Typical examples of epoxy resins are:
I) Polyglycidyl and poly(&bgr;-methylglycidyl)esters which are obtainable by reacting a compound containing at least two carboxyl groups in the molecule and epichlorohydrin or &bgr;-methylepichlorohydrin. The reaction is conveniently carried out in the presence of a base.
Compounds containing at least two carboxyl groups in the molecule may suitably be aliphatic polycarboxylic acids. Examples of such polycarboxylic acids are oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, suberic acid, azelaic acid or dimerised or trimerised linoleic acid. It is, however, also possible to use cycloaliphatic polycarboxylic acids such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid or 4-methylhexahydrophthalic acid. Aromatic polycarboxylic acids can also be used, typically phthalic acid, isophthalic acid and terephthalic acid.
II) Polyglycidyl or poly(&bgr;-methylglycidyl)ethers which are obtainable by reacting a compound containing at least two free alcoholic hydroxyl groups and/or phenolic hydroxyl groups and epichlorohydrin or &bgr;-methylepichlorohydrin, under alkaline conditions or in the presence of an acid catalyst and subsequent treatment with an alkali.
The glycidyl ethers of this type are typically derived from acyclic alcohols, typically from ethylene glycol, diethylene glycol and higher poly(oxyethylene)glycols, 1,2-propanediol or poly(oxypropylene) glycols, 1,3-propanediol, 1,4-butanediol, poly(oxytetramethylene)glycols, 1,5-pentanediol, 1,6-hexanediol, 2,4,6-hexanetriol, glycerol, 1,1,1-trimethylol-propane, pentaerythritol, sorbitol, as well as from polyepichlorohydrins. They may also be derived from cycloaliphatic alcohols such as 1,4-cyclohexanedimethanol, bis(4-hydroxy-cyclohexyl)methane or 2,2-bis(4-hydroxycyclohexyl)propane, or they contain aromatic nuclei such as N,N-bis(2-hydroxyethyl)aniline or p,p′-bis(2-hydroxyethylamino)diphenyl-methane.
The glycidyl ethers may also be derived from mononuclear phenols, typically from resorcinol or hydroquinone, or they are derived from polynuclear phenols such as bis(4-hydroxyphenyl)methane, 4,4′-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis (4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, as well as from novolaks obtainable by condensation of aldehydes such as formaldehyde, acetaldehyde, chloral or furfuraldehyde, with phenols such as phenol, or with phenols which are substituted in the nucleus by chlorine atoms or C
1
-C
9
alkyl groups, for example 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol, or by condensation with bisphenols of the type cited above.
III) Poly-(N-glycidyl) compounds obtainable by dehydrochlorination of the reaction products of epichlorohydrin with amines which contain at least two amino hydrogen atoms. These amines are typically aniline, n-butylamine, bis(4-aminophenyl)methane, m-xylylenediamine or bis(4-methylaminophenyl)methane. The poly(N-glycidyl) compounds also include triglycidyl isocyanurate, N,N′-diglycidyl derivatives of cycloalkylene ureas such as e
Gulakowski Randy
Neuman, Esq. Kristin H.
Proskauer Rose LLP
Vantico Inc.
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