Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1996-08-28
2004-01-13
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S015000, C528S031000, C524S588000, C427S387000, C428S447000
Reexamination Certificate
active
06677407
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to silicone release coatings which cure at low temperatures. More particularly, the present invention relates to curable silicone release coatings which contain certain silylated acetylenic inhibitors.
Acetylenic compounds which are suitable as inhibitors in curable silicone coating compositions have been disclosed. For example, Shirahata et al. in U.S. Pat. No. 4,465,818 discloses organopolysiloxane compositions, which react by way of a hydrosilylation reaction to undergo an increase in viscosity, and have longer pot life and/or shorter cure time than analogous compositions in the art by incorporating therein an unsaturated hydrocarbon having from 6 to 10 carbon atoms, a terminal acetylenic linkage, and an olefinic linkage conjugated therewith. Chandra et al. in U.S. Pat. No. 4,472,563 discloses improved inhibitors for the reaction of silicon hydride containing silicones with vinyl or hydroxyl containing silicones, the inhibitors being mixtures of conjugated ene-ynes and vinylcyclosiloxanes. Sasaki et al. in U.S. Pat. No. 4,559,396 discloses room temperature storable, heat-curable organopolysiloxane compositions which comprise silicon-bonded vinyl radicals, silicon-bonded hydrogen atoms, a platinum-type compound and an unsaturated hydrocarbon compound of the conjugated ene-yne type provide a release surface for tacky substances when coated onto the surface of a base material and heated. VanWert et al. in U.S. Pat. No. 5,082,894 discloses a one-part organosiloxane composition that cures by platinum catalyzed hydrosilylation which contains an acetylenic alcohol containing at least 8 carbon atoms such as 3,5-dimethyl-1-hexyn-3-ol as the catalyst inhibitor. Ushio et al. in U.S. Pat. No. 5,210,126 discloses a silicone rubber composition prepared by mixing a diorganopolysiloxane which contains 0.1 to 5 percent of a low molecular weight organosiloxane with a vapor pressure at 200° C. of at least 10 mm Hg, with at least 90 weight percent of a low-molecular-weight organosiloxane with a boiling point not exceeding 250° C. at 760 mm Hg and a curing agent, which can further contain a curing retarder such as 3-methyl-1-butyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-3-pentene-1-yne, 3,5-dimethyl-3-hexene-1-yne, and methylvinylsiloxane cyclics.
VanWert et al. in U.S. Pat. No. 5,270,425 discloses one part organosiloxane compositions comprising a vinyltrialkoxysilane, an epoxy-substituted alkoxysilane, a vinyl-containing hydroxylated polyorganosiloxane, a chelated aluminum compound, and an inhibitor composition comprising a mixture of at least one cyclic methylvinylsiloxane and an acetylenic alcohol containing at least 6 carbon atoms.
Silicone coatings which contain silylated acetylenic inhibitors have been disclosed. For example, Kookootsedes et al. in U.S. Pat. No. 3,445,420 discloses a curable composition which can be stored in the presence of a catalyst but cures by heating or exposure to the atmosphere is a mixture of an olefin containing organosilicon polymer, an organosilicon compound containing silicon-bonded hydrogen atoms, a platinum catalyst, and an acetylenic compound such as C
6
H
5
Si(OCH
2
C≡CH)
3
, C
6
H
5
Si(CH
3
)(OCH(CH
3
)C≡CH)
2
, or (HC≡CSi(CH
3
)
2
)O.
Lee et al. in U.S. Pat. No. 4,032,502 discloses organopolysiloxane compositions for use in a liquid injection molding process are produced by mixing a vinyl-endblocked polydiorganosiloxane fluid copolymer, a treated reinforcing silica filler, a platinum containing catalyst, a dimethylhydrogensiloxane curing agent, and acetylenic silanes as an inhibitor for the catalyst. The acetylenic silanes are disclosed as being of the formulae R″
v
Si(OC(CH
3
)
2
C≡CH)
4−v
or
where R″ is independently methyl, ethyl, phenyl, or 3,3,3-trifluoropropyl and v is an integer from 0 to 2 inclusive. Shirahata in U.S. Pat. No. 4,472,562 discloses heat curable polyorganosiloxane compositions comprising a vinyl containing polyorganosiloxane, a polyorganosiloxane containing silicon-bonded hydrogen atoms, a platinum, palladium, or rhodium catalyst, and specified acetylenic silanes as storage stabilizers. The silanes are of the general formula R
4
Si(OCR
5
R
6
C≡CH)
3
where R
4
, R
5
, and R
6
are identical or different monovalent hydrocarbon radicals containing from 1 to 10 carbon atoms, or R
5
and R
6
jointly form a divalent hydrocarbon radical.
Japanese Pat. Publication No. 1-12786 (12,786/1989) discloses a silicone composition for mold-release paper, composed of (1) 100 parts by weight of an organopolysiloxane that has a viscosity of 50 centistokes or greater at 25° C., contains at least two bonds between a vinyl group and a silicon atom in each molecule and has an essentially linear structure, (2) 0.2 to 50 parts by weight of an organopolysiloxane having at least two bonds between hydrogen atoms and silicon atoms in each molecule, (3) 2-500 ppm of a platinum compound in terms of metallic platinum with respect to component (1) indicated above, and (4) 0.1 to 10 parts by weight of an organosilicon compound having the general formula
wherein R
1
, R
2
, R
3
, R
4
, and R
5
denote hydrogen atoms or the same or different substituted or unsubstituted aliphatic monovalent hydrocarbon groups having 1 to 10 carbon atoms that has a boiling point of 250° C. or less and has acetylenic unsaturated groups that are compatible with the aforementioned first or second organopolysiloxane components. Examples of the specific compounds disclosed include
However, nowhere in the above Japanese Pat. Publication are these types of silylated acetylenic inhibitors disclosed in combination with higher alkenyl containing organopolysiloxane polymers.
SUMMARY OF THE INVENTION
The present invention relates to a method of making silicone release coating compositions comprising mixing a vinyl functional organopolysiloxane, an organohydrogensilicon compound, a platinum group metal-containing catalyst, and certain silylated acetylenic inhibitors.
The present invention further relates to a method of making silicone release coating compositions comprising mixing an organopolysiloxane compound having alkenyl groups which contain at least four carbon atoms, an organohydrogensilicon compound, a platinum group metal-containing catalyst, and silylated inhibitors.
It is an object of the present invention to produce silicone release coatings which cure quickly at low temperatures.
It is a further object of this invention to produce silicone release coatings which can be coated on heat sensitive substrates.
DETAILED DESCRIPTION OF THE INVENTION
The first embodiment of the present invention relates to a method of making a curable silicone release coating composition comprising (I) mixing (A) an organopolysiloxane compound having its formula selected from the group consisting of (i) R
1
3
SiO(R
2
SiO)
x
(RR
1
SiO)
y
SiR
1
3
, (ii) R
1
3
SiO(R
2
SiO)
x
SiR
1
3
, and (iii) R
1
3
SiO(RR
1
SiO)
y
SiR
1
3
, wherein R is independently selected from monovalent hydrocarbon or halohydrocarbon radicals free of aliphatic unsaturation and having from 1 to 20 carbon atoms, R
1
is independently selected from the group consisting of R and vinyl, x has a value of from greater than zero to 7000, and y has a value of from greater than zero to 350 with the proviso that there are at least two vinyl groups per compound, (B) an organohydrogensilicon compound, (C) a platinum group metal-containing catalyst, (D) a silylated acetylenic compound having its formula selected from the group consisting of:
and optionally (E) a diluent.
The monovalent radicals of R in compound (A) can contain up to 20 carbon atoms and include hydrocarbon or halohydrocarbon radicals free of aliphatic unsaturation. Monovalent hydrocarbon radicals free of aliphatic unsaturation include alkyl radicals such as methyl, ethyl, propyl, butyl, hexyl, octyl, and decyl, cycloaliphatic radicals such as cyclohexyl, aryl radicals such as phenyl, tolyl, and xylyl, and aralkyl radicals such as benzyl and phenylethyl. Highly preferred mon
Bilgrien Carl Joseph
Mealey Shawn Keith
Skinner Michael Ward
Dow Corning Corporation
Sellers Robert E. L.
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