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
1999-08-30
2001-07-24
Dawson, Robert (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...
C528S032000, C528S041000, C528S038000, C427S515000, C522S099000, C522S031000, C522S066000, C430S280100, C430S281100
Reexamination Certificate
active
06265496
ABSTRACT:
This application is an application under 35 U.S.C. Section 371 of International Application Number PCT/FR97/02382, filed on Dec. 22, 1997.
The present invention relates to stable compositions based on polyorganosiloxanes containing cationically crosslinkable functional groups, to their use for preparing anti-adherent or anti-adhesive coatings and to articles consisting of a solid support, at least one surface of which is made anti-adherent or anti-adhesive by coating with the said functional polyorganosiloxanes crosslinked by photochemical activation and/or by activation with a beam of electrons.
It is known practice, for preparing anti-adhesive coatings, to use compositions based on a polyorganosiloxane containing functional groups (such as epoxy, vinyl ether, etc.) to which is added a cationic initiator onium salt for the crosslinking (U.S. Pat. Nos. 4,450,360; 4,576,999; 4,640,967).
Compositions based on UV-crosslinkable polyorganosiloxanes of the prior art can have problems of stability and of ageing in the presence or absence of light. In particular, it has been found that in the presence of a photoinitiator in the said compositions conditioned in liquid form, uncontrolled polymerization reactions of the polyorganosiloxanes took place in the medium, this occurring without UV irradiation.
Furthermore, when a photoinitiator is used under liquid conditioning, it has a tendency to degrade, and gives reduced performance if it is used after a long period of storage.
The Applicant has found and developed novel compositions based on at least one polyorganosiloxane (A) containing crosslinkable functional groups, these compositions having none of the drawbacks of the compositions of the prior art. In particular, these novel compositions based on polyorganosiloxane(s) (A) contain at least one stabilizing amino agent consisting of a polyorganosiloxane (B) functionalized with at least one amino group. These novel crosslinkable compositions have markedly improved stability on storage and also markedly improved stability during their use. Thus, uncontrolled polymerization reactions in the compositions are all but eliminated, without, however, reducing the ability of the said compositions to crosslink under controlled conditions.
The novel compositions in accordance with the invention comprise at least one polyorganosiloxane (A) containing crosslinkable functional groups, which is stable on use and on storage, characterized in that the said compositions comprise at least one stabilizing amino agent consisting of a polyorganosiloxane (B) functionalized with at least one amino group, and a system for initiating curing under radiation, in particular UV, the polyorganosiloxane (B) being miscible with the polyorganosiloxane (A).
In general, the stable and crosslinkable compositions according to the invention are in liquid and homogeneous form.
Advantageously, the amino group of the polyorganosiloxane (B) is an amino group in which the amine is stearically hindered. More specifically, the polyorganosiloxane (B), used in the compositions according to the invention, is a linear, cyclic or three-dimensional polyorganosiloxane with a molecular mass of from 200 to 200,000 grams per mole and which comprises identical or different units of general formula (I):
R
a
X
b
V
c
SiO
4
-
(
a
+
b
+
c
)
2
(
I
)
in which:
(1)
a=0, 1, 2 or 3
b=0, 1, 2, or 3
c=0, 1, 2 or 3
a+b+c≦3
(2) the symbols R are identical and/or different and represent a monovalent hydrocarbon-based radical chosen from linear or branched alkyl radicals containing from 1 to 4 carbon atoms, a hydrogen radical, linear or branched alkoxy radicals containing from 1 to 4 carbon atoms, a phenyl radical and, preferably, a hydroxyl radical, an ethoxy radical, a methoxy radical or a methyl radical,
(3) the symbols X are cationically crosslinkable, identical or different functional residues, preferably an epoxy functional and/or vinyloxy functional group, connected to the silicon of the polyorganosiloxane via a divalent radical containing from 2 to 20 carbon atoms and which can contain at least one hetero atom, preferably oxygen,
(4) the symbols V are identical and/or different functional residues and represent a residue containing one (or more) stearically hindered piperidyl group(s) chosen from:
For the residues of formula (II):
R
1
is a divalent hydrocarbon-based radical chosen from:
linear or branched alkylene radicals containing 2 to 18 carbon atoms;
alkylenecarbonyl radicals in which the alkylene part is linear or branched contains 2 to 20 carbon atoms;
alkylenecyclohexylene radicals in which the alkylene part is linear or branched contains 2 to 12 carbon atoms and the cyclohexylene part contains an OH group and optionally 1 or 2 alkyl radicals containing 1 to 4 carbon atoms;
the radicals of formula —R
4
—O—R
4
in which the radicals R
4
, which may be identical or different, represent alkylene radicals containing 1 to 12 carbon atoms;
the radicals of formula —R
4
—O—R
4
in which the radicals R
4
have the meanings given above and one or both of them are substituted with one or two —OH group(s);
the radicals of formula —R
4
—COO—R
4
in which the radicals R
4
have the meanings given above;
the radicals of formula —R
5
—O—R
6
—O—CO—R
5
in which the radicals R
5
and R
6
, which may be identical or different, represent alkylene radicals containing 2 to 12 carbon atoms and the radical R
6
is optionally substituted with a hydroxyl radical;
U represents —O— or —NR
7
—, R
7
being a radical chosen from a hydrogen atom, a linear or branched alkyl radical containing 1 to 6 carbon atoms and a divalent radical of formula:
in which R
1
has the meaning given above, R
2
and R
3
have the meanings given below and R
8
represents a linear or branched divalent alkylene radical containing from 1 to 12 carbon atoms, one of the valency bonds (that of R
8
) being connected to the atom of —NR
7
—, the other (that of R
1
) being connected to a silicon atom;
the radicals R
2
are identical or different and are chosen from linear or branched alkyl radicals containing 1 to 3 carbon atoms and the phenyl radical;
the radical R
3
represents a hydrogen radical or the radical R
2
or O&Circlesolid;.
For the residues of formula (III):
R
9
is chosen from a trivalent group of formula:
in which m represents a number from 2 to 20,
and a trivalent group of formula:
in which p represents a number from 2 to 20;
U′ represents —O— or NR
10
—, R
10
being a radical chosen from a hydrogen atom and a linear or branched alkyl radical containing 1 to 6 carbon atoms;
R
2
and R
3
have the same meanings as those given with regard to formula (II).
According to one preferred embodiment of the invention, the polyorganosiloxane (B) has a molecular mass of from 1000 to 50,000 grams per mole.
In accordance with the definition of the polyorganosiloxanes (B) given above, the latter preferably have the average general formula (IV):
in which:
(1′) the symbols R are identical or different and have the meanings given above;
(2′) the symbols X are identical or different and have the meanings given above;
(3′) the symbols V are identical or different and have the meanings given above;
(4′) the symbols Z are identical or different and represent R and/or V as defined above; and
(5′) x, y, z and w are totally independent fractional values chosen such that:
4<x+y+z+w<10,000, preferably 10<x+y+z+w<2000,
0<x<8000, preferably 2<x<1500,
0<y<1000, preferably 1<y<200,
0.2<z<500, preferably 1<z<100,
and 0<w<300, preferably 0<w<100.
In particular, the best results were obtained with polyorganosiloxanes (B) in which the independent fractional values x, z, and w are such that:
20<x+y+z+w<100
5<x<80
2<y<10
1<z<50
and 0<w<5.
Moreover, the symbol Z is preferably a stearically hindered cyclic amine comprising branched alkyl groups of 1 to 4 carbon atoms &agr; to the ni
Priou Christian
Soldat Andre
Chimie Rhodia
Dawson Robert
Peng Kuo-Liang
Seugnet Jean-Louis
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