Method for the prevention of mist formation in a device comprising rolls during the coating of flexible supports with a cross-linkable liquid silicone composition
The invention relates to the general field of coating various flexible supports, such as sheets of paper or synthetic polymer (polyolefin, polyester, etc) sheets or fabric sheets, with a silicone on high-speed rolls. The invention relates to an efficient method for preventing mist formation when coating flexible supports with a liquid silicone composition precursor of cross-linked coatings, said coating process being performed using a coating device that includes a roll operating at a high speed.
1. A process for combating appearance of mist during coating of one or more flexible supports with a liquid silicone composition X which is crosslinkable by polyaddition, by dehydrogenative condensation, by polycondensation, by a cationic route or by a radical route and is a precursor of silicone coating(s), comprising the following I) and II):
I) preparing said liquid silicone composition X and
II) coating said liquid silicone composition X on a flexible support using a roll coating device, wherein, in I) said liquid silicone composition X is admixed with an anti-misting additive E obtained by reacting, optionally for 30 minutes to 12 hours, at a temperature of between 10° C. and 100° C.:
per 100 parts by weight of at least one organopolysiloxane F comprising from 10 to 80 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organopolysiloxane F,
from 0.01 to 1 part by weight of at least one compound chosen from the group consisting of:
an organopolysiloxane G comprising from 85 to 400 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organopolysiloxane G,
an organic compound H comprising from 300 to 1000 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organic compound H, and
mixtures thereof, and
from 5 to 40 parts by weight of at least one organopolysiloxane N comprising from 10 to 80 mmol of amine functions per 100 g of organopolysiloxane N,
the amounts of said compounds F, G, H and N employed being such that the initial molar ratio Ri=nAcr/nH is between 3.8 and 7, where nAcr is the total number of moles of (meth)acrylate functions of compounds F, G and H and nH is the number of moles of hydrogen atoms bonded to a nitrogen atom of the organopolysiloxane N.
2. The process for combating appearance of mist during coating of one or more flexible supports as claimed in claim 1 , in which the organopolysiloxane N is chosen from the organopolysiloxanes comprising siloxy units (I.1) and (I.2) of the following formulae:
Y
a
Z
b
1
SiO
4
-
(
a
+
b
)
2
;
(
I
.1
)
Z
c
2
SiO
4
-
c
2
(
I
.2
)
in which:
a=1 or 2, b=0, 1 or 2 and a+b=1, 2 or 3
c=1, 2 or 3
symbol Y, which may be identical or different, represents a functional group of formula (I.3):
-E 1 -(NH-G) h -(NH 2 ) i (I.3)
in which:
h=0 or 1;
i=0 or 1;
h+i=1 or 2;
E 1 represents a divalent aliphatic, cycloaliphatic or aromatic hydrocarbon radical comprising from 1 to 30 carbon atoms, optionally aliphatic and containing from 1 to 10 carbon atoms;
when it is present, G represents an aliphatic hydrocarbon radical comprising from 1 to 10 carbon atoms which is monovalent when i=0 and divalent when i=1;
the symbols Z 1 and Z 2 , which may be identical or different, represent a monovalent hydrocarbon radical having from 1 to 30 carbon atoms and optionally comprising one or more unsaturations and/or one or more fluorine atoms, a hydroxyl group or a radical —OR 1 with R 1 representing a linear, cyclic or branched C 1 -C 10 hydrocarbon radical, and optionally Z 1 and Z 2 represent a monovalent hydrocarbon group chosen from the group consisting of alkyl groups having from 1 to 8 carbon atoms, alkenyl groups having from 2 to 6 carbon atoms and aryl groups having from 6 to 12 carbon atoms optionally comprising one or more fluorine atoms, a hydroxyl group, or a radical —OR 1 with R 1 representing a linear, cyclic or branched C 1 -C 10 hydrocarbon radical, and optionally chosen from the group consisting of a methyl, ethyl, propyl, 3,3,3-trifluoropropyl, vinyl, hydroxyl, ethoxyl, methoxyl, xylyl, tolyl and phenyl group; said organopolysiloxane N comprising, per molecule, at least two siloxy units (I.1) bearing at least one functional group of formula (I.3).
3. The process for combating appearance of mist during coating of one or more flexible supports as claimed in claim 2 , in which the organopolysiloxane N is chosen from the organopolysiloxanes comprising siloxy units (I.1) and (I.2) of the following formulae:
Y
a
Z
b
1
SiO
4
-
(
a
+
b
)
2
;
(
I
.1
)
Z
c
2
SiO
4
-
c
2
(
I
.2
)
in which:
a=1 or 2, b=0, 1 or 2 and a+b =2 or 3
c=2 or 3.
4. The process for combating appearance of mist during coating of one or more flexible supports as claimed in claim 1 , in which the organopolysiloxanes F and G comprise:
a1) at least one unit of the following formula (VI.1):
R 6 a Z 3 b SiO (4−a−b)/2 (VI.1)
in which formula:
the symbols R 6 , which may be identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, optionally by halogen atoms, or an alkoxy radical —OR 7 with R 7 being a hydrogen atom or a hydrocarbon radical comprising from 1 to 10 carbon atoms,
the symbols Z 3 are monovalent radicals of formula -y-(Y′) n in which:
y represents a linear or branched C 1 -C 18 polyvalent alkylene radical optionally extended by divalent C 1 to C 4 oxyalkylene or polyoxyalkylene radicals, which is optionally substituted by a hydroxy radical,
Y′ represents a monovalent alkenylcarbonyloxy radical, and
n is equal to 1, 2 or 3, and optionally n is equal to 1,
a is an integer equal to 0, 1 or 2, b is an integer equal to 1 or 2 and the sum a+b=1, 2 or 3; and
a2) units of the following formula (VI.2):
R 8 a SiO (4−a)/2 (VI.2)
in which formula:
the symbols R 8 , which may be identical or different, each represent a linear or branched C 1 to C 18 alkyl group, a C 6 to C 12 aryl or aralkyl group, optionally substituted, optionally by halogen atoms, and
a is an integer equal to 0, 1, 2 or 3.
5. The process for combating appearance of mist during coating of one or more flexible supports as claimed in claim 1 , in which the organic compound H comprising at least two (meth)acrylate functions is chosen from the group consisting of alkanediol diacrylates and alkanediol dimethacrylates, including 1,3-butylene glycol diacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate and trimethylolpropane triacrylate.
6. The process for combating appearance of mist during coating of one or more flexible supports as claimed in claim 1 , in which the initial molar ratio Ri=nAcr/nH is between 4.5 and 7, optionally between 5 and 7 and optionally between 5.3 and 6.8.
7. The process for combating appearance of mist during coating of one or more flexible supports as claimed in claim 1 , in which said liquid silicone composition X which is a precursor of silicone coating(s) comprises:
at least one organopolysiloxane A1 which is crosslinkable by the radical route,
at least one radical photoinitiator C1, and
optionally at least one adhesion modulator system K.
8. A process for preparing an anti-misting additive E by reacting, optionally for 30 minutes to 12 hours, at a temperature of between 10° C. and 100° C.:
per 100 parts by weight of at least one organopolysiloxane F comprising from 10 to 80 mmol of (meth)acrylate functions per 100 g of organopolysiloxane F,
from 0.01 to 1 part by weight of at least one compound chosen from the group consisting of:
an organopolysiloxane G comprising from 85 to 400 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organopolysiloxane G,
an organic compound H comprising from 300 to 1000 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organic compound H, and
mixtures thereof, and
from 5 to 40 parts by weight of at least one organopolysiloxane N comprising from 10 to 80 mmol of amine functions per 100 g of organopolysiloxane N,
the amounts of said compounds F, G, H and N employed being such that the initial molar ratio Ri=nAcr/nH is between 3.8 and 7, where nAcr is the total number of moles of (meth)acrylate functions of compounds F, G and H and nH is the number of moles of hydrogen atoms bonded to a nitrogen atom of the organopolysiloxane N.
9. An anti-misting additive E obtained by reacting, optionally for 30 minutes to 12 hours, at a temperature of between 10° C. and 100° C.:
per 100 parts by weight of at least one organopolysiloxane F comprising from 10 to 80 mmol of (meth)acrylate functions per 100 g of organopolysiloxane F,
from 0.01 to 1 part by weight of at least one compound chosen from the group consisting of:
an organopolysiloxane G comprising from 85 to 400 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organopolysiloxane G,
an organic compound H comprising from 300 to 1000 mmol of (meth)acrylate, and optionally acrylate, functions per 100 g of organic compound H, and
mixtures thereof, and
from 5 to 40 parts by weight of at least one organopolysiloxane N comprising from 10 to 80 mmol of amine functions per 100 g of organopolysiloxane N,
the amounts of said compounds F, G, H and N employed being such that the initial molar ratio Ri=nAcr/nH is between 3.8 and 7, where nAcr is the total number of moles of (meth)acrylate functions of compounds F, G and H and nH is the number of moles of hydrogen atoms bonded to a nitrogen atom of the organopolysiloxane N.
10. A liquid silicone composition X which is crosslinkable by polyaddition, by dehydrogenative condensation, by polycondensation, by a cationic route or by a radical route, comprising the anti-misting additive E obtained as claimed in claim 9 .
11. A product comprising the anti-misting additive E as defined in accordance with claim 9 for reducing the appearance of mist during coating of one or more flexible supports with a liquid silicone composition X which is a precursor of silicone coating(s).