Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2002-06-12
2004-05-25
Peng, Kuo-Liang (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S689000, C502S326000, C528S031000, C427S301000
Reexamination Certificate
active
06740418
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a low temperature curable coatings, more particularly to addition curable organopolysiloxane coatings that cure rapidly at low temperature.
BRIEF DESCRIPTION OF THE RELATED ART
Addition curable release coating compositions and their use as release coatings are known, see, for example, coassigned U.S. Pat. No. 4,448,815. A layer of such coating is typically applied to a substrate, such as paper, from a reactive coating bath which contains an alkenyl-functional organopolysiloxane, a hydride-functional organopolysiloxane, a precious metal catalyst and a cure inhibitor. Once applied, the layer of coating is cured by exposing the coated substrate to elevated temperature.
The cure inhibitor retards cure of the coating and enables a balance between a long useful coating bath life at low temperature and rapid cure speed at elevated temperature to be maintained. There is a constant desire in the art to provide increased cure speed without compromising bath life.
The need to subject the coated substrate to elevated temperature to cure the coating layer introduces some drawbacks to the use of addition cure organopolysiloxane release coatings coating process, in the form of energy costs, a need to rehydrate coated paper substrates after curing and a limited ability to use such coatings to coat temperature sensitive substrates, such as, for example, some polymer films. Due to these drawbacks, there is a desire in the art to provide coatings that are curable at lower temperature without compromising bath life.
SUMMARY OF THE INVENTION
In a first aspect, the present invention is directed to a method of making a coated substrate.
In a first embodiment, a method of making a coated substrate comprises: applying a layer of a coating composition, said coating composition comprising an alkenyl functional organopolysiloxane and a hydride functional organopolysiloxane, to a substrate, said substrate comprising a catalytically effective amount of a precious metal catalyst, and allowing the layer to cure.
In a second embodiment, a method of making a coated substrate comprises: applying a layer of a first component of a coating composition, said first component comprising an alkenyl functional organopolysiloxane and a catalytically effective amount of a precious metal catalyst to a substrate, applying a layer a second component of a coating composition, said second component comprising a hydride functional organopolysiloxane, to the substrate, and allowing the layers of coating composition to cure.
In a third embodiment, a method of making a coated substrate comprises: applying a layer of a coating composition, said coating composition comprising organopolysiloxane having both alkenyl and hydride radicals present on the same molecule, to the substrate, said substrate comprising a catalytically effective amount of a precious metal catalyst, and allowing the layer to cure.
The method of the present invention allows the use of a non-catalyzed coating bath having a very long useful life, while providing a highly reactive coating layer that may be rapidly cured at low temperature and thereby avoids some of the drawbacks, for example, high energy costs, the need to rehydrate paper substrates and the limited applicability to temperature sensitive substrates, that characterize typical addition cure coatings.
Another aspect of the present invention is directed to a catalyzed article comprising a substrate selected from paper sheets, polymer films, polymer coated paper sheets and metal foils, and a precious metal catalyst disposed on at least one surface of the substrate.
Another aspect of the present invention is directed to a method of forming a catalyzed article, comprising: forming a dilute catalyst by dissolving a precious metal catalyst in a volatile organic or organosiloxane solvent; or by dispersing a precious metal catalyst in a binder composition; or by dispersing a precious metal catalyst in a film forming polymer composition, and applying the dilute catalyst to the substrate, wherein the composition of the dilute catalyst and application rate of dilute catalyst on the substrate are selected to provide a selected amount of precious metal per unit area of substrate surface.
DETAILED DESCRIPTION OF THE INVENTION
Alkenyl functional organopolysiloxanes suitable for use in the method of the present invention are those including structural units of the formula (I):
R
1
a
SiO
4−a/2
(I)
wherein:
each R
1
is independently hydroxyl or a monovalent hydrocarbon radical, and
a is an integer wherein 0≦a≦3,
provided that at least two R
1
groups per molecule of such alkenyl functional organopolysiloxane are each independently alkenyl radicals.
As used herein “monovalent hydrocarbon radical” means a monovalent acyclic hydrocarbon radical, a monovalent alicyclic hydrocarbon radical or a monovalent aromatic hydrocarbon radical.
As used herein, the terminology “acyclic hydrocarbon radical” means a monovalent straight chain or branched hydrocarbon radical, preferably containing from 2 to 20 carbon atoms per radical, which may be saturated or unsaturated and which may be optionally substituted or interrupted with one or more functional groups, such as, for example, carboxyl, cyano, hydroxy, halo and oxy. Suitable monovalent acyclic hydrocarbon radicals include, for example, alkyl, alkenyl, alkynyl, hydroxyalkyl, cyanoalkyl, carboxyalkyl, carboxamide, a]kylamido and haloalkyl, such as, for example, methyl, ethyl, sec-butyl, tert-butyl, octyl, decyl, dodecyl, cetyl, stearyl, ethenyl, propenyl, butynyl, hydroxypropyl, cyanoethyl, carboxymethyl, chloromethyl and 3,3,3-fluoropropyl.
As used herein the term “alkyl” means a saturated straight or branched monovalent hydrocarbon radical. In a preferred embodiment, monovalent alkyl groups are selected from linear or branched alkyl groups containing from 1 to 12 carbons per group, such as, for example, methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, decyl, dodecyl.
As used herein the term “alkenyl” means a straight or branched monovalent terminally unsaturated hydrocarbon radical, preferably containing from 2 to 10 carbon atoms per radical, such as, for example, ethenyl, 2-propenyl, 3-butenyl, 5-hexenyl, 7-octenyl and ethenylphenyl.
As used herein, the terminology “monovalent alicyclic hydrocarbon radical” means a monovalent 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 radicals, each preferably containing from 2 to 6 carbon atoms per group, halo radicals or other functional groups and which, in the case of a monovalent alicyclic hydrocarbon radical containing two or more rings, may be fused rings. Suitable monovalent alicyclic hydrocarbon radicals include, for example, cyclohexyl and cyclooctyl.
As used herein, the terminology “monovalent aromatic hydrocarbon radical” means a monovalent hydrocarbon radical containing one or more aromatic rings per radical, which may, optionally, be substituted on the aromatic rings with one or more alkyl radicals, each preferably containing from 2 to 6 carbon atoms per group, halo radicals or other functional groups and which, in the case of a monovalent aromatic hydrocarbon radical containing two or more rings, may be fused rings. Suitable monovalent aromatic hydrocarbon radicals include, for example, phenyl, tolyl, 2,4,6-trimethylphenyl, 1,2-isopropylmethylphenyl, 1-pentalenyl, naphthyl, anthryl.
In a preferred embodiment, the alkenyl functional organopolysiloxane comprises one or more organopolysiloxane polymers or copolymer of the formula (II):
M
1
b
M
vi
c
D
1
d
D
vi
e
T
1
f
T
vi
g
Q
h
(II)
wherein:
M
1
is R
2
3
SiO
½
,
M
vi
is R
3
2
R
4
SiO
½
,
D
1
is R
5
2
SiO
{fraction (2/2)}
,
D
vi
is R
6
R
7
SiO
{fraction (2/2)}
,
T
1
is R
8
SiO
{fraction (3/2)}
,
T
vi
is R
9
SiO
{fraction (3/2)}
,
Q is SiO
{fracti
Lewis Larry N.
O'Brien Michael J.
General Electric Company
Peng Kuo-Liang
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