Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2001-02-07
2003-02-11
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S447000, C524S492000, C524S493000, C524S588000, C528S015000, C528S031000, C528S032000, C528S042000
Reexamination Certificate
active
06517946
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to addition reaction-curable compositions, and particularly to addition reaction-curable compositions which provide fluorinated elastomers having a good adhesion to various base materials and excellent bond durability.
2. Prior Art
Curable fluorinated elastomer compositions which are curable by means of an addition reaction between alkenyl groups and hydrosilyl groups are already known to the art. JP-A 9-95615 discloses compositions endowed with tack properties by the further addition, as a third constituent, of an organopolysiloxane having hydrosilyl groups and epoxy and/or trialkoxysilyl groups. Such compositions can be cured by heating for a short period of time and, when cured, are capable of bonding to a broad range of base materials. The resulting cured product has excellent resistance to solvents, chemicals and heat, excellent low-temperature properties, a low water-vapor permeability and outstanding electrical characteristics.
Such compositions bond to various kinds of base materials when heat-cured, but the bond is of insufficient durability. Hence, these prior-art compositions have a poor long-term reliability as adhesives. Because good long-term reliability is essential in automotive parts and in electrical and electronic components, there exists a strong desire for improved bond durability in compositions of this type which are used as adhesives.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide curable compositions capable of forming a fluorinated elastomer having good adhesion to various types of base materials and also endowed with excellent bond durability.
The inventors have discovered that curable compositions comprising (A) a specific type of fluorinated amide compound, (B) a specific fluorinated organohydrogen-siloxane as a crosslinking agent and a chain extender, (C) a platinum group compound as a catalyst, (D) an organosiloxane having at least one hydrogen atom bonded directly to a silicon atom and at least one epoxy group and/or trialkoxysilyl group bonded to a silicon atom through a carbon atom or a carbon atom and an oxygen atom per molecule, and preferably having also a fluoroalkyl or perfluoropolyether group, (E) silica powder as a filler and (F) a specific organosilane or organosiloxane as a surface treatment agent for the silica powder are endowed with excellent resistance to solvents, chemicals and heat, outstanding low-temperature properties, a low water-vapor permeability, and excellent electrical properties. Moreover, such compositions bond well to various types of base materials, and have outstanding bond durability.
Accordingly, the invention provides a curable composition comprising:
(A) a fluorinated amide compound of general formula (1) below
wherein R
1
is a substituted or unsubstituted monovalent hydrocarbon group,
R
2
is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group,
Q is a group of general formula (2)
in which R
2
is as defined above and R
3
is a substituted or unsubstituted divalent hydrocarbon group which may be separated by at least one atom selected from among oxygen, nitrogen and silicon atoms, or a group of general formula (3)
in which R
4
and R
5
are each independently a substituted or unsubstituted divalent hydrocarbon group, Rf is a divalent perfluoroalkylene or divalent perfluoropolyether group, and the letter “a” is 0 or a positive integer;
(B) a fluorinated organohydrogensiloxane having at least one monovalent perfluorooxyalkyl, monovalent perfluoroalkyl, divalent perfluorooxyalkylene or divalent perfluoroalkylene group and at least two hydrosilyl groups per molecule;
(C) a catalytic amount of a platinum group compound;
(D) an organosiloxane having, per molecule, at least one hydrogen atom bonded directly to a silicon atom and at least one epoxy group and/or trialkoxysilyl group bonded to a silicon atom through a carbon atom or a carbon atom and an oxygen atom;
(E) a silica powder having a BET specific surface area of at least 50 m
2
/g; and
(F) an organosilane or organosiloxane having, per molecule, at least one monovalent perfluorooxyalkyl, monovalent perfluoroalkyl, divalent perfluorooxyalkylene or divalent perfluoroalkylene group and at least one hydroxy group and/or alkoxy group bonded directly to a silicon atom;
wherein component B is included in an amount corresponding to 0.5 to 5 moles of hydrosilyl groups per mole of aliphatic unsaturated groups in the composition.
DETAILED DESCRIPTION OF THE INVENTION
The curable composition of the present invention includes a fluorinated amide compound of formula (1) below as the base polymer, a fluorinated organohydrogensiloxane as a crosslinking agent or chain extender for the base polymer, a platinum group compound as the catalyst, an organosiloxane as an adhesion-imparting agent, a silica powder as a filler, and a fluorinated organosilane or organosiloxane as a surface treatment agent for the silica powder.
The first essential constituent of the inventive composition, referred to hereinafter as component A, is a fluorinated amide compound of the following general formula (1)
In formula (1), R
1
is a substituted or unsubstituted monovalent hydrocarbon group of preferably 1 to 10 carbons, especially 1 to 8 carbons, and preferably without an aliphatic unsaturated bond. Illustrative examples include alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, octyl and decyl; cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl; alkenyl groups such as vinyl, allyl, propenyl, isopropenyl, butenyl and hexenyl; aryl groups such as phenyl, tolyl, xylyl and naphthyl; aralkyl groups such as benzyl, phenylethyl and phenylpropyl; and halogen-substituted alkyl groups composed of any of the above groups on which some or all of the hydrogen atoms are replaced with halogen atoms, such as chloromethyl, chloropropyl, bromoethyl, 3,3,3-trifluoropropyl and 6,6,6,5,5,4,4,3,3-nonafluorohexyl.
R
2
is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group of preferably 1 to 10 carbons, especially 1 to 8 carbons, and preferably without an aliphatic unsaturated bond. The monovalent hydrocarbon groups are exemplified by the same groups as mentioned above for R
1
, including alkyl groups such as methyl, ethyl, propyl and isopropyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl and tolyl; and halogen-substituted alkyl groups composed of any of the above groups on which some of the hydrogen atoms are replaced with halogen atoms, such as chloromethyl, chloropropyl, 3,3,3-trifluoropropyl and 6,6,6,5,5,4,4,3,3-nonafluorohexyl.
Q is a group of general formula (2) or general formula (3) below.
In formula (2), R
2
is as defined above. R
3
may be any substituted or unsubstituted divalent hydrocarbon group, although a divalent hydrocarbon group of 1 to 20 carbons, and especially 2 to 10 carbons, is preferred. Specific examples include alkylene groups such as methylene, ethylene, propylene, methylethylene, butylene and hexamethylene; cycloalkylene groups such as cyclohexylene; arylene groups such as phenylene, tolylene, xylylene, naphthylene and biphenylene; any of the above groups in which some of the hydrogen atoms have been replaced with halogen atoms; and combinations of such substituted or unsubstituted alkylene and arylene groups.
The R
3
group may be linked through one or more intervening atom selected from among oxygen, nitrogen and silicon atoms. If the atom is oxygen, the linkage may be —O-. If the atom is nitrogen, the linkage may be —NR′—, where R′ is a hydrogen atom or an alkyl or aryl group of 1 to 8 carbons, and preferably 1 to 6 carbons. If the atom is silicon, the linkage may be a group containing a linear or cyclic organosiloxane, such as those of the following formulas or an organosilylene group.
In the above formulas, R″ is an alkyl or aryl group of 1 to 8 carbons which may be exempli
Matsuda Takashi
Shiono Mikio
Dawson Robert
Millen, White, Zelano & Braningan, P.C.
Shin-Etsu Chemical Co. , Ltd.
Zimmer Marc S.
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