Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-06-25
2001-11-20
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S588000, C524S860000, C524S863000, C525S477000, C556S458000, C556S459000, C528S017000, C528S018000, C427S387000
Reexamination Certificate
active
06319982
ABSTRACT:
BACKGROUND OF THE INVENTION
Silicone based aqueous dispersions crosslinkable into elastomeric sealants and coatings are known in the art. They generally comprise an oil in water emulsion of a polyorganosiloxane with hydroxy endgroups, a crosslinking agent, a non-siliceous inorganic filler and a curing catalyst. In particular, a great deal of effort has been directed to emulsions of standard &agr;,&ohgr;-dihydroxypolydimethylsiloxane fluids in combination with many different crosslinkers as a basis for producing silicone latex sealants. The crosslinkers have included alkoxysilanes (U.S. Pat. No. 4,100,129), colloidal silica (U.S. Pat. No. 4,221,688), sodium silicate (U.S. Pat. No. 4,224,849), silsesquioxanes (U.S. Pat. No. 3,355,406), siliconates (EP 266 729), and reactive resins (U.S. Pat. No. 4,554,187). More recently the use of a disiloxane curative has been disclosed (WO 98/13410, Rhone Poulenc). Unfortunately, these emulsions have suffered from poor shelf stability, poor adhesion and poor physical properties.
Combinations of silicone emulsions and acrylic emulsions have been recently suggested to address some of these issues (U.S. Pat. No. 5,360,851 and EP 246 537, Rhone Poulenc). Similarly, U.S. Pat. No. 5,621,038 to Chen et al. discloses the modification of dispersion polymers with vinylsilanes containing hindered alkoxy groups. However, it does not mention silicone polymers modified with these vinyl silanes. U.S. Pat. No. 5,686,523 discloses the mixture of a dispersion polymer modified with a silyl group and an additional silane additive in the form of an alkoxysilane with hindered alkoxy groups.
U.S. Pat. No. 5,714,532, incorporated herein by reference, describes a series of alkoxysilanes which can be formulated into stable emulsions for waterborne coating or sealant formulations as crosslinkers or adhesion promoters.
Co-pending U.S. application Ser. No. 09/149,337, filed Sep. 8, 1998, incorporated herein in its entirety by reference extends the use of hindered silanes as additives to waterborne acrylic sealants. Increases in adhesion, shelf life and sealant physical properties are noted. In this technology the silanes are used as additives to a resin system or are incorporated into the resin during resin synthesis.
SUMMARY OF THE INVENTION
The present invention pertains to hindered siloxane compounds and to uses of said compositions in a variety of applications including RTV latex sealants, and more generally self-crosslinking sealants, as well as adhesives and coatings.
In one aspect the invention is a storage-stable aqueous silicone emulsion composition which cures upon drying, the composition comprising a blend of:
a) one or more emulsions which collectively comprise a reactive polymer/crosslinker system, the reactive polymer/crosslinker system comprising at least one condensable polyorganosiloxane polymer and at least one crosslinking compound, which may be the same or different than said condensable polyorganosiloxane polymer, the crosslinking compound having a plurality of hindered alkoxy groups of the formula —OR
3
thereon, where R
3
is an alkyl or alkoxy-substituted alkyl, aryl or aralkyl group and has from two to ten carbon atoms; and
b) a separate aqueous emulsion comprising a silicone condensation catalyst. The reactive polymer/crosslinker system suitably includes a compound having thereon a group of the formula:
—SiR
2
a
(OR
3
)
b
I
where R
2
is alkyl, alkoxy-substituted alkyl, aryl or aralkyl, and has from one to twelve carbon atoms; R
3
is as previously defined; a is 0 or 1; b is 2 or 3 and a+b=3.
The compound having thereon a group of formula I may include at least one novel polyorganosiloxane polymer having thereon a plurality of groups of the formula II:
R
1
—SiR
2
a
(OR
3
)
b
II
linked to silicon atoms of at least one polyorganosiloxane backbone, where R
1
is a divalent organic group and R
2
, R
3
, a and b are as previously defined. In such cases, the polyorganosiloxane polymer is self-crosslinking so that the reactive polymer/crosslinker system may consist only of the polyorganosiloxane polymer. These novel polymers constitute a further aspect of the invention.
Alternatively the reactive polymer/crosslinker system may include an emulsified silanol fluid and one or more crosslinker and/or adhesion promoter compounds of the formula III:
R
4
—SiR
2
a
(OR
3
)
b
III
wherein R
2
, R
3
, a and b are as previously defined and R
4
is a vinyl group or a hydrocarbon group having from three to thirty carbon atoms which is optionally substituted with an organic functional group or an SiR
2
a
(OR
3
)
b
group. Reactive polymer/crosslinker systems also may be formulated which include a polyorganosiloxane polymer having thereon a plurality of groups of the formula II together with one or both of a silanol fluid and a compound of formula III.
Silanes and organosiloxane compounds having hydrolyzable groups wherein the hydrolyzable groups are hindered alkoxy groups defined by the formula OR
3
have good stability in water so that they may be formulated into aqueous silicone emulsion compositions in a blend with a separately emulsified catalyst. By separately emulsifying the catalyst component, the catalyst can be kept isolated from the reactive polymer and crosslinker components of the composition until the composition is dried. As the composition dries the non-volatile components coalesce, bringing catalyst, polymer and crosslinker components into contact, thereby initiating curing.
DETAILED DESCRIPTION OF THE INVENTION
In formulae I, II, III, above, R
1
is exemplified by ethylene, propylene, propenylene, 1,4-butylene, 1,2-butylene, 1,3-butylene, amylene, phenethylene, &agr;-methylphenethylene, and the like. R
2
is exemplified by methyl, ethyl, n-propyl, n-butyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, lauryl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, isopropyl, isobutyl, sec-butyl, isoamyl, sec-amyl, 4-methyl-2-pentyl, 2-ethylhexyl and phenyl. R
3
is exemplified by ethyl, n-propyl, n-butyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, isopropyl, isobutyl, sec-butyl, isoamyl, sec-amyl, 4-methyl-2-pentyl, 2-ethylhexyl and phenyl. R
3
groups having branched structures are preferred as they hydrolyze slower.
In formula III, above when R
4
is an unsubstituted saturated or aromatic hydrocarbon group the compound of formula III will generally be considered to be a crosslinker whereas when R
4
is an aliphatically unsaturated hydrocarbon group or has an organic functional group substituent the compound of formula III will generally be considered to be an adhesion promoter. In either case, however, the compound of formula III can function as a crosslinking compound within the definition of the invention herein. R
4
hydrocarbon groups may be alkyl, aralkyl, alkaryl, or aryl groups. Specific examples include propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, octyl, xylyl, benzyl, phenyl, cyclopentyl, cyclohexyl, phenylmethyl, phenylethyl, and the like. Examples of optional organic-functional group substituents which may be included on the R
4
group include mercapto, epoxy, methacryloxy, acryloxy, chloro, bromo, iodo, cyano, ketone, aldehyde, carboxylate, carboxylic acid, silyl ester (e.g., —SiR
2
b
(OR
3
)
3−b
where R
2
and R
3
are as previously defined), amine, alkylamine, dialkylamine, arylamine, diarylamine, ureide, amide, isocyanurate, and alkoxy groups substituted with any of the foregoing. R
4
may also be a 3-30 carbon alkenyl group such as vinyl, allyl, oleyl, linoleyl, linolenyl, etc.
Polyorganosiloxanes having thereon a plurality of groups of the formula:
—R
1
SiR
2
a
(OR
3
)
b
II
linked to silicon atoms of the polyorganosiloxane backbone, where R
1
is a divalent hydrocarbon group; R
2
is alkyl, alkoxy-substituted alkyl, aryl or aralkyl, and has from one to twelve carbon atoms; R
3
is alkyl or alkoxy-substituted alkyl, aryl or aralkyl group, and has from two to ten carbon atoms; a is 0 or 1; b is 2 or 3
Cooke Jeff A.
Huang Misty Weiyu
Waldman Bruce A.
CK Witco Corporation
Dawson Robert
Dilworth Michael P.
Grandinetti Paul
Peng Kuo-Liang
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