Compositions – Electrically conductive or emissive compositions
Reexamination Certificate
2001-06-07
2004-07-20
Boyer, Charles (Department: 1751)
Compositions
Electrically conductive or emissive compositions
C524S403000, C524S426000, C528S026000, C528S027000, C528S029000, C528S031000
Reexamination Certificate
active
06764616
ABSTRACT:
The present invention relates to a composition comprising an epoxy resin, various poly-siloxanes and fluorinated compounds, to crosslinked products obtainable by curing such a composition and to the use of such a composition as electrical insulating material.
Epoxy resins are frequently used as electrical insulating material on account of their good mechanical properties and their high specific resistance. Cycloaliphatic epoxy resins are especially suitable for outdoor applications because of their high resistance to weathering, but the problem arises, especially in regions having high levels of precipitation and air pollution, that a conductive dirt/water layer can form on the surface of the insulator which leads to leakage currents and arcing and may have consequences ranging from damage to the insulator up to total failure. Even only slightly soiled epoxy-based insulators can undergo a rise in surface conductivity if the surface becomes eroded by weathering in the course of time and the water is better able to wet the resulting roughened layer.
As disclosed in U.S. Pat. No. 3,926,885, epoxy resins can be provided with hydrophobic properties by the addition of polysiloxane/polyether copolymers and OH-terminated polysiloxanes, but the adhesion of the resulting material to metal is not sufficient for all applications.
JP-A 2-305454 describes epoxy resin mixtures having a high degree of stability towards moisture which, in addition to comprising an epoxy novolak and a phenolic resin, also comprise small amounts of a cyclic dimethylsiloxane. Although, in those compositions, the corrosion caused by binding of water on the surface is largely prevented, a hydrophobicity effect sufficient for use as an insulator is not achieved with such systems.
WO 98/32138 describes a resin system suitable as electrical insulating material that is based on curable mixtures of epoxy resins and specific silicone oligomers having terminal glycidyl groups. As a result of the curing, the silicone oligomers become part of the crosslinked structure that is formed, so that known properties of silicones, such as hydrophobicity and good resistance to weathering, can be imparted to the cured material. A disadvantage is the use of expensive commercially available silicone oligomers and a poor hydrophobicity transfer effect.
It has now been found that compositions comprising an epoxy resin, at least two specific polysiloxanes and a non-ionic, fluoroaliphatic surface-active reagent are able to yield storage-stable emulsions that in the fully cured state have a pronounced hydrophobicity transfer effect and recovery effect.
The present invention relates to a composition comprising
(a) an epoxy resin,
(b) an OH-terminated polysiloxane,
(c) a cyclic polysiloxane and
(d) a non-ionic, fluoroaliphatic surface-active reagent.
The amounts of components (a) to (c) in the compositions according to the invention can vary within wide limits.
Preference is given to compositions comprising,
based on the total composition (a), (b), (c) and (d),
from 77.0 to 97.99% by weight, especially from 86.0 to 96.95% by weight, component (a),
from 1.0 to 10.0% by weight, especially from 2.0 to 6.0% by weight, component (b),
from 1:0 to 10.0% by weight, especially from 1.0 to 5.0% by weight, component (c) and
from 0.01 to 3.0% by weight, especially from 0.05 to 3.0% by weight, component (d),
the sum of components (a), (b), (c) and (d) being 100% by weight.
As component (a) of the compositions according to the invention there are suitable any type of epoxide that contains at least one glycidyl or &bgr;-methylglycidyl group, a linear alkylene oxide group or a cycloalkylene oxide group.
Examples of suitable epoxy resins are polyglycidyl and poly(&bgr;-methylglycidyl)ethers obtainable by reaction of a compound containing at least two free alcoholic and/or phenolic hydroxyl groups per molecule with epichlorohydrin or &bgr;-methylepichlorohydrin under alkaline conditions, or alternatively in the presence of an acid catalyst with subsequent alkali treatment.
Suitable starting compounds for the preparation of such glycidyl or &bgr;-methylglycidyl ethers are, for example, acyclic alcohols, such as ethylene glycol, diethylene glycol and higher poly(oxyethylene)glycols, propane-1,2-diol and poly(oxypropylene)glycols, propane-1,3-diol, butane-1,4-diol, poly(oxytetramethylene)glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylolpropane, pentaerythritol or sorbitol, cycloaliphatic alcohols, such as resorcitol, quinitol, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxy-cyclohexyl)propane and 1,1-bis(hydroxymethyl)cyclohex-3-ene, and alcohols having aromatic nuclei, such as N,N-bis(2-hydroxyethyl)aniline and p,p′-bis(2-hydroxyethylamino)diphenyl-methane.
Further suitable dihydroxy compounds for the preparation of glycidyl or &bgr;-methylglycidyl ethers are mononuclear phenols, such as resorcinol and hydroquinone, polynuclear phenols, such as bis(4-hydroxyphenyl)methane, 4,4-dihydroxydiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) and 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, and novolaks, for example phenol and cresol novolaks.
Polyglycidyl and poly(&bgr;-methylglycidyl) esters are obtainable by reaction of a compound containing two or more carboxylic acid groups per molecule with epichlorohydrin, glycerol dichlorohydrin or &bgr;-methylepichlorohydrin in the presence of alkali. Such polyglycidyl esters can be derived from aliphatic polycarboxylic acids, e.g. oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or dimerised or trimerised linoleic acid, from cycloaliphatic polycarboxylic acids, such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid and 4-methylhexahydrophthalic acid, and from aromatic polycarboxylic acids, such as phthalic acid, isophthalic acid and terephthalic acid.
Further epoxides suitable as component (a) are poly(N-glycidyl) compounds, for example the products obtainable by dehydrochlorination of the reaction products of epichlorohydrin and amines containing at least two amino hydrogen atoms, such as aniline, n-butylamine, bis(4-aminophenyl)methane and bis(4-methyl-aminophenyl)methane. Also included are triglycidyl isocyanurate as well as N,N′-diglycidyl derivatives of cyclic alkyleneureas, such as ethylene-urea and 1,3-propyleneurea and hydantoins, such as 5,5-dimethylhydantoin. Poly(S-glycidyl) compounds, for example the di-S-glycidyl derivatives of dithiols, such as ethane-1,2-dithiol and bis(4-mercaptomethylphenyl) ether, are likewise suitable.
Preferably the compositions comprise as component (a) a cycloaliphatic epoxy resin or an epoxidation product of a natural unsaturated oil or a derivative thereof.
The term “cycloaliphatic epoxy resin” in the context of this invention denotes any epoxy resin having cycloaliphatic structural units, that is to say it includes both cycloaliphatic glycidyl compounds and &bgr;-methylglycidyl compounds as well as epoxy resins based on cyclo-alkylene oxides.
Suitable cycloaliphatic glycidyl compounds and Vmethylglycidyl compounds are the glycidyl esters and &bgr;-methylglycidyl esters of cycloaliphatic polycarboxylic acids, such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid, 3-methylhexahydrophthalic acid and 4-methylhexahydrophthalic acid.
Further suitable cycloaliphatic epoxy resins are the diglycidyl ethers and &bgr;-methylglycidyl ethers of cycloaliphatic alcohols, such as 1,2-dihydroxycyclohexane, 1,3-dihydroxycyclohexane and 1,4-dihydroxycyclohexane, 1,4-cyclohexanedimethanol, 1,1-bis(hydroxymethyl)cyclohex-3ene, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and bis(4-hydroxycyclohexyl)sulfone.
Examples of epoxy resins having cycloalkylene oxide structures are bis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentylglycidyl ether, 1,2-bis(2,3-epoxycyclopentyl)ethane, vinyl cyclohexene dioxide, 3,4-epoxycyclohexylm
Beisele Christian
Kainmüller Thomas
Tang Qian
Boyer Charles
Hamlin D. G.
Huntsman Advanced Materials Americas Inc.
Levato Tiffany A.
Neuman Kristin H.
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