Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-08-17
2001-10-30
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C526S279000, C528S018000, C528S034000, C528S901000, C556S413000
Reexamination Certificate
active
06310170
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polymers which can be cured by silane cure chemistry and to compositions made therefrom.
BACKGROUND OF THE INVENTION
Silane cure chemistry is used in different types of polymer technologies and compositions made therefrom, such as silylated acrylics, RTV silicones, silylated polyurethanes, silylated polyethers and others, for crosslinking. Such systems, when the backbones are organic polymers, are often referred to as hybrids, hybrid polymers, hybrid systems, or something similar since they can combine organic polymer chemistry with inorganic (silicon-based) cure chemistry. For this application RTV silicone systems are included in the compositions because they employ similar cure chemistry, even though they typically provide quite different cured properties. It is well known that the type of silane structure located on the polymer for crosslinking directly impacts the composition's properties, such as speed of cure, flexibility, adhesion or mechanical properties like tensile and tear strength at break.
Typical examples for the influence of the silane structure terminating the polymer chain on the system's properties after final cure are given for silylated urethane polymers e.g. in U.S. Pat. No. 4,374,237 to Berger, et al., where curable isocyanate-terminated polyurethanes are at least partially reacted with a secondary amine containing silane monomer having two trialkoxy silane groups. Other silane end-capped urethane polymers and sealants are disclosed in U.S. Pat. No. 3,627,722 to Seiter, which described polyurethane sealants such as alkylaminoalkyltrialkoxysilanes, mercaptoalkyltrialkoxysilanes, and arylaminoalkyltrialkoxysilanes containing a significant percentage, but preferably less than all, of terminal isocyanate groups endblocked with —Si(OR)
3
, where R was a lower alkyl group.
To overcome the problem of insufficient flexibility, U.S. Pat. No. 4,645,816 to Pohl and Osterholtz teaches a novel class of room-temperature, moisture-curable, silane-terminated polyurethanes bearing terminal isocyanate groups reacted with a silane monomer having one dialkoxy silane group and an organo-functional group with at least one active hydrogen. The polymers are crosslinked to produce elastomeric networks with improved flexibility.
Another approach to reducing the crosslinking density of the cured elastomers, is to use secondary aminosilanes with bulky substituents on the nitrogen as silane endcappers, preferably reacting all free isocyanate endgroups with these secondary amino silanes. EP 676,403 to Feng reports that the use of arylaminosilanes, particularly having one dialkoxy silane group provided the added benefit of further improved flexibility. Zwiener, et al. disclosed in U.S. Pat. No. 5,364,955 similar benefits using certain N-alkoxysilylalkyl-aspartic acid esters. U.S. Pat. No. 4,345,053 to Rizk, et al., describes a moisture-curable silane-terminated polymer prepared by reacting a polyurethane having terminal active hydrogen atoms with an isocyanato organosilane having a terminal isocyanate group and at least one hydrolyzable alkoxy group bonded to silicon. U.S. Pat. No. 4,625,012 to Rizk and Hsieh, describes a moisture-curable polyurethane having terminal isocyanate groups and silane groups having at least one hydrolyzable alkoxy group bonded to silicon, in which the silane groups may be pendant to the chain.
Similar teaching is given for other silane cure hybrid systems. Linear and branched silane terminated polyether polymers are mixed in different ratios to vary flexibility and mechanical properties. RTV silicone crosslinker functionality leads to tailored physical properties.
Improved cure speed of silane terminated polyurethanes using a small amount of amino silane additives such as N-(beta-aminoethyl)-gamma-aminopropyltrimethoxysilane has been shown in U.S. Pat. No. 3,979,344 by Bryant and Weis.
BRIEF SUMMARY OF THE INVENTION
This invention relates to the use of novel aminoalkylsilanes as adhesion promoters that have have a branched linkage to the silicon atom. Preferred silane adhesion promoters employed in the invention have a branched alkylene linkage between the silicon and amino groups thereof.
Inventive compositions employing hybrid polymers and the silane adhesion promoters of the present invention, show comparable to superior adhesion performance as compared to gamma-aminopropylsilane adhesion promoter on conventional substrates such as glass and aluminum. In addition, the compositions have improved flexibility significantly leading to higher elongation, lower modulus and softer sealant materials. The flexibility and adhesion enhancement allow for the realization of performance more nearly like that of RTV silicone sealants for building construction applications using hybrid organic polymer systems such as silylated polyurethanes.
The inventive compositions comprise:
a) a silylated polymer having terminal or pendant alkoxysilyl, aryloxysilyl or alkyloximinosilyl groups thereon; and
b) a silane adhesion promoter of the formula:
where R
1
is a branched or cyclic alkylene group, an arylene group or an alkarylene group, any of which optionally may be interrupted by one or more ether oxygen atoms or a (poly)sulfide bridge, provided that R
1
has at least 4 carbon atoms; R
2
is an alkyl, aryl or alkaryl radical having 1 to 6 carbons; R
3
is a C
1
to C
6
alkoxy group or a C
3
to C
5
ketoximato group; R
4
is hydrogen, a hydrocarbon group, which may optionally be substituted, or a group which will thermally deblock to form an amine group containing the nitrogen atom to which it is attached; and z is 0 or 1.
The silylated polymers employed in such compositions may be organic or inorganic. Particularly preferred polymers are silylated polyurethanes.
Polyorganosiloxanes having at least two silanol groups may also be used with the adhesion promoters specified above, in which case it is preferred that the composition of polymer and adhesion promoter be prepared at the time of use.
DETAILED DESCRIPTION OF THE INVENTION
The entire disclosures of all U.S. patents and other published documents and any copending U.S. patent applications mentioned anywhere herein are expressly incorporated herein by reference.
Unless otherwise indicated herein, “alkyl” may be linear, branched or cyclic; “aryl” includes alkaryl groups such as tolyl and aralkyl groups such as benzyl; “alkylene” may be linear, branched or cyclic and includes alkylene groups having pendent or internal aryl groups such as 1,4-diethylenephenylene:
or 3-phenyl-1,3-propylene; “arylene” includes arylene groups having pendant alkyl groups; and “alkarylene” refers to a divalent hydrocarbon in which one open valency is aryl and the other is alkyl.
The adhesion promoting silanes of the invention may be represented by the formula:
where R
1
is a branched or cyclic alkylene group, an arylene group or an alkarylene group, any of which optionally may be interrupted by one or more ether oxygen atoms or a (poly)sulfide bridge, provided that R
1
has at least 4 carbon atoms; R
2
is an alkyl, aryl or alkaryl radical having 1 to 6 carbons; R
3
is a C
1
to C
6
alkoxy group or a C
3
to C
5
ketoximato group; R
4
is hydrogen, a hydrocarbon group, which may optionally be substituted, or a group which will thermally deblock to form an amine group containing the nitrogen atom to which it is attached; and z is 0 or 1.
R
1
suitably contains from 4 to about 12 carbon atoms and is exemplified by branched or cyclic groups such as 1,3-butylene, 1,2-butylene or 2,2-dimethyl-1,3-propylene; 3-methylbutylene, 3,3-dimethylbutylene, 2-ethylhexylene, 1,4-diethylenephenylene, 3-phenyl-1,3-propylene; 1,4-cyclohexylene, and 1,4-diethylenecyclohexylene:
divalent ether and polyether groups of the formula:
—C
r
H
2r
—(OC
s
H
2s
)
q
—
where q is 1-50, preferably 1-5, r and s are integers of 2-6 and at least one —C
r
H
2r
— or —(OC
s
H
2s
)— group is branched; and divalent thioether or polysulfide-containing groups of the formula:
—C
t
H
2t
—S
u
—C
t
H
2t
—
where t is 2
Johnston Robert R.
Lehmann Patrice
CK Witco Corporation
Dawson Robert
Ma Shirley S.
Zimmer Marc S.
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