Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
1999-06-21
2001-05-15
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C427S387000, C428S451000, C524S588000, C525S100000, C525S479000, C156S329000
Reexamination Certificate
active
06231990
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable
FEDERALLY SPONSORED RESEARCH
Not applicable
FIELD OF THE INVENTION
The present invention relates to primer compositions, more specifically to primer compositions for bonding room temperature vulcanizable (“RTV”) silicone elastomers to diverse substrates.
BRIEF DESCRIPTION OF THE RELATED ART
The use of primers for the purpose of improving the adhesion of RTV silicone elastomers are known, see for example, U.S. Pat. Nos. 4,681,636 and 4,749,741.
U.S. Pat. No. 4,147,685 discloses a primer composition that is a reaction product of methyl or butyl methacrylate and an acrylate functional silane in an organic solvent. The reaction product is made by heating the primer ingredients at a temperature of 50 to 80° C. in the presence of a peroxide catalyst. The compositions disclosed in the '685 patent exhibit improved adhesion to plastics, but have been found to be deficient when the solids content of the primer as unreacted acrylate functional silane monomer is less than 10%. Additionally, the compositions disclosed in the '685 patent exhibit high volatile organic compounds (VOCs).
What is needed in the art is a primer composition that provides improved adhesion to diverse substrates, particularly concrete and plastics, while exhibiting lower VOCs.
SUMMARY OF THE INVENTION
The present invention is directed to a low VOC primer composition suitable for use with room temperature vulcanizable silicone elastomers, comprising the product formed by combining:
(i) a polyorganosiloxane resin;
(ii) an acrylic resin;
(iii) an organotitanate;
(iv) a silane or partial hydrolyzate thereof; and
(v) an organic liquid in amount effective to dissolve components (i), (ii), (iii) and (iv) of the primer composition.
The primer composition of the present invention provides improved adhesion to diverse substrates, particularly concrete.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment, the primer composition of the present invention comprises, based on 100 parts by weight (“pbw”) of the primer composition, from 1 pbw to 80 pbw, more preferably from 5 pbw to 50 pbw, still more preferably from 15 pbw to 25 pbw, of the polyorganosiloxane resin; from 0.1 pbw to 25 pbw, more preferably from 0.5 pbw to 15 pbw, still more preferably from 1 pbw to 10 pbw, of the acrylic resin; from 1 pbw to 25 pbw, more preferably from 5 pbw to 20 pbw, still more preferably from 8 pbw to 15 pbw, of the organotitanate; from 0.01 pbw to 20 pbw, more preferably from 0.1 pbw to 10 pbw, still more preferably from 0.2 pbw to 5 pbw, of the silane or partial hydrolyzate thereof; from 0.5 pbw to 95 pbw, more preferably from 25 pbw to 85 pbw, still more preferably from 50 pbw to 75 pbw, of the organic liquid.
Polyorganosiloxane Resin
Polyorganosiloxane resins that are suitable as the polysiloxane resin component of the composition of the present invention are those resins containing structural units according to the formula (I):
M
a
D
b
T
c
(I)
wherein:
M is R
1
R
2
R
3
SiO
1/2
;
D is R
4
R
5
SiO
2/2
;
T is R
6
SiO
3/2
;
R
1
, R
2
, R
3
, R
4
, R
5
and R
6
are each independently hydrogen or monovalent hydrocarbon radicals; and
a, b and c are each integers, wherein 1≦a≦10,000, 1≦b≦10,000 and 1≦c≦10,000.
Suitable monovalent hydrocarbon radicals include monovalent acyclic hydrocarbon radicals, monovalent alicyclic hydrocarbon radicals and monovalent aromatic hydrocarbon radicals.
As used herein, the terminology “acyclic hydrocarbon radical” means a straight chain or branched hydrocarbon radical, preferably containing from 2 to 24 carbon atoms per radical, which may be saturated or unsaturated. Suitable monovalent acyclic hydrocarbon radicals include, for example, methyl, sec-butyl, tert-butyl, octyl, decyl, dodecyl, cetyl, stearyl, propenyl, and butynyl.
As used herein, the terminology “alicyclic hydrocarbon radical” means a radical containing one or more saturated hydrocarbon rings, preferably containing from 4 to 10 carbon atoms per ring, per radical which may optionally be substituted on one or more of the rings with one or more alkyl or alkylene groups, each preferably containing from 2 to 6 carbon atoms per groups and which, in the case of two or more rings, may be fused rings. Suitable monovalent alicyclic hydrocarbon radicals include, for example, cyclohexyl, cyclooctyl.
As used herein, the term “aromatic hydrocarbon radical” means a hydrocarbon radical containing one or more aromatic rings per radical, which may optionally be substituted on the one or more aromatic rings with one or more alkyl or alkylene groups, each preferably containing from 2 to 6 carbon atoms per group, or other functional groups and which, in the case of two or more rings, may be fused rings. Suitable monovalent aromatic hydrocarbon radicals include, for example, aryl radicals such as, for example, phenyl, naphthyl and aralkyl, such as, for example, phenethyl.
In a preferred embodiment, R
1
, R
2
, R
3
, R
4
and R
5
are each independently (C
1
-C
8
)alkyl, aryl or aralkyl.
In a more highly preferred embodiment, R
1
, R
2
, R
3
, R
4
and R
5
are each independently methyl, propyl, octyl, phenyl or diphenyl.
Acrylic Resin
Acrylic resins that are suitable as the acrylic resin component of the composition of the present invention are homopolymers, comprising first repeating units derived from one monomer selected from (meth)acrylic ester monomers, (meth)acrylic acid monomers and (meth)acrylamide monomers and, optionally, second repeating units derived from one or more monoethylenically unsaturated monomers copolymerizable therewith. As used herein, the term “(meth)acrylic” refers collectively to acrylic and methacrylic, “(meth)acrylate” refers collectively to acrylates and methacrylates, and the term “(meth)acrylamide” refers collectively to acrylamides and methacrylamides.
Suitable (meth)acrylic ester monomers include, for example, alkyl (meth)acrylate monomers, preferably (C
1
-C
8
)alkyl (meth)acrylate monomers such as, for example, methyl methacrylate, butyl acrylate, ethylhexylmethacrylate; hydroxy(C
1
-C
8
)alkyl (meth)acrylate monomers such as, for example, hydroxyethyl methacrylate; (C
4
-C
8
)cycloalkyl (meth)acrylate monomers such as, for example, cyclohexyl methacrylate. Suitable (meth)acrylic acid monomers include, for example, acrylic acid, methacrylic acid. Suitable (meth)acrylamide monomers include acrylamide and methacrylamide. Suitable copolymerizable monomers include, for example, monoethylenically unsaturated carboxylic acids such as, for example, itaconic acid; maleimide monomers such as, for example, N-alkyl maleimides, N-aryl maleimides, maleic anhydride, vinyl esters such as, for example, vinyl acetate, vinyl versatate and vinyl propionate.
In a preferred embodiment, the acrylic resin comprises an acrylic resin selected from poly(methyl methacrylate), poly(acrylonitrile), poly(acrylamide), poly(acrylic acid), and poly(methacrylic acid).
In a preferred embodiment, the acrylic resin has a weight average molecular weight of from 40,000 to 250,000 grams per mole (“g/mol”), more preferably from 75,000 to 200,000 g/mol, and still more preferably from 90,000 to 150,000 g/mol.
In a preferred embodiment, the acrylic resin comprises a resin selected from polymethylmethacrylate, polyacrylic acid, polyacrylamide, polymethacrylic acid or polyacrylonitrile. In a most preferred embodiment, the acrylic resin is Paraloid® B-72 acrylic resin (sold by Rohm and Haas Company).
Organotitanate
Organotitanates that are suitable as the organotitanate component of the composition of the present invention include, for example, organotitanate esters, titanium complexes, titanium chelate compounds, partially alkoxylated partial chelates of titanium, as well as partial hydrolysis-condensation products of any of these compounds.
In a preferred embodiment, the organotitanate component is an organotitanate ester according to the structural formula:
Ti(OR
7
)
4
wherein each R
7
is independently (C
1
-C
8
)alkyl.
Preferably the organotitanate component comprises an or
Bayly Brian P.
Fahrenkopf Timothy J.
Lin Chiu-Sing
Lucas Gary M.
Dawson Robert
General Electric Company
Zimmer Marc S.
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