U.S. patent application number 10/512977 was filed with the patent office on 2006-04-27 for assembly for hydrosylilation, method for preparing same and silicone compositions incorporating same.
This patent application is currently assigned to RHODIA CHIMIE. Invention is credited to Sebastien Sterin, Remi Thiria.
Application Number | 20060089455 10/512977 |
Document ID | / |
Family ID | 29404172 |
Filed Date | 2006-04-27 |
United States Patent
Application |
20060089455 |
Kind Code |
A1 |
Sterin; Sebastien ; et
al. |
April 27, 2006 |
Assembly for hydrosylilation, method for preparing same and
silicone compositions incorporating same
Abstract
Process for preparing catalyst assemblies by mixing a metal
catalyst capable of catalyzing a hydrosilylation reaction and an
organophosphorus inhibitor of the formula (I) ##STR1## or of
formula (VIII) P(OR).sub.3, either by mixing the inhibitor into a
solution of catalyst in an unsaturated silane or siloxane or by
mixing the inhibitor into a gum or oil at a temperature greater
than the melting temperature or softening temperature of the
organophosphorus compound, then mixing the catalyst. Catalyst
assemblies, process for preparing one-component silicone
compositions, and resultant compositions.
Inventors: |
Sterin; Sebastien; (Lyon,
FR) ; Thiria; Remi; (Lyon, FR) |
Correspondence
Address: |
BUCHANAN INGERSOLL PC;(INCLUDING BURNS, DOANE, SWECKER & MATHIS)
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
RHODIA CHIMIE
BOULOGNE BILANCOURT
FR
|
Family ID: |
29404172 |
Appl. No.: |
10/512977 |
Filed: |
April 25, 2003 |
PCT Filed: |
April 25, 2003 |
PCT NO: |
PCT/FR03/01305 |
371 Date: |
August 30, 2005 |
Current U.S.
Class: |
524/863 ;
524/866; 528/12; 528/15; 528/23 |
Current CPC
Class: |
B01J 2531/828 20130101;
B01J 31/1865 20130101; C08G 77/20 20130101; C07F 15/0086 20130101;
C08L 83/04 20130101; C08L 83/00 20130101; C08L 2666/52 20130101;
C08L 83/04 20130101; B01J 31/185 20130101; C08L 83/04 20130101;
B01J 31/1608 20130101; C08K 5/0091 20130101; B01J 2231/321
20130101; C08G 77/12 20130101; B01J 31/2291 20130101; C08L 83/00
20130101 |
Class at
Publication: |
524/863 ;
524/866; 528/012; 528/015; 528/023 |
International
Class: |
C08L 83/04 20060101
C08L083/04; C08L 83/07 20060101 C08L083/07; C08G 77/08 20060101
C08G077/08 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 29, 2002 |
FR |
02/05380 |
Dec 2, 2002 |
FR |
02/15161 |
Claims
1-38. (canceled)
39. A process for preparing a hydrosilylation-crosslinkable
one-component silicone composition comprising at least one
polyorganosiloxane (POS) A bearing ethylenic and/or acetylenic
unsaturation(s), at least one polyorganohydrosiloxane (POS) B, a
hydrosilylation catalyst and an inhibitor which is an
organophosphorus compound inhibiting the action of the catalyst at
room temperature, said process comprising premixing said
hydrosilylation catalyst and said inhibitor to form a
catalyst/inhibitor additive and then combining said additive with
said at least one polyorganosiloxane (POS) A bearing ethylenic
and/or acetylenic unsaturation(s) and said at least one
polyorganohydrosiloxane (POS) B, wherein said inhibitor is of the
following formula (I): ##STR13## in which: R, R.sup.1, R.sup.2,
R.sup.3 and R.sup.4, which are identical or different, represent a
linear, branched or cyclic alkyl radical or an aryl radical which
is substituted or unsubstituted, especially: i. a linear or
branched alkyl radical having particularly 2 to 30 carbon (C)
atoms, preferably 2 to 12 C, ii. an alkyl radical containing one or
more rings, especially 1 or 2, it being possible in particular for
one ring to have 4 to 14 C, preferably 5 to 8 C, or iii. an aryl or
alkylaryl radical containing one or more fused or unfused aromatic
rings, especially 1 or 2 rings, it being possible for one ring to
contain 4 to 14 C, preferably 6 to 8 C, which is or are optionally
substituted by 1 or more, especially 1 to 2, linear or branched
alkyl(s), especially having 1 to 12 C, preferably 4 to 12 C; or
wherein the inhibitor is of formula (VIII) P(OR).sub.3 in which R
is an alkylaryl radical having in particular 7 to 31 carbon atoms,
preferably substituted phenyl radicals.
40. The process according to claim 39, wherein in the formula (I),
R is a cyclic alkyl radical or an aryl radical, preferably
biphenyl.
41. The process according to claim 39, wherein in the formula (I),
R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are cyclic alkyl radicals,
aryl radicals or alkylaryl radicals, preferably substituted phenyl
radicals.
42. The process according to claim 39, wherein the inhibitor is of
the formula (II): ##STR14## in which the radicals R.sup.5, which
are identical or different, preferably identical, are linear or
branched alkyls having in particular 1 to 12 C, preferably 4 to 12
C, and preferably represent t-Bu.
43. The process according to claim 39, wherein the inhibitor is of
the formula (IX): ##STR15## in which R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5, which are identical or different, represent H,
a linear or branched aliphatic radical, saturated, of formula
C.sub.nH.sub.2n+1, or unsaturated, of formula C.sub.mH.sub.2m-1, or
a radical of formula C.sub.nF.sub.2n+1, with n=1 to 15 and m=3 to
15, it not being possible for all of these radicals together to
represent H.
44. The process according to claim 39, wherein the inhibitor is:
##STR16##
45. The process according to claim 39, wherein the catalyst is a
platinum/unsaturated siloxane complex, especially a
platinum/vinylsiloxane complex, preferably a Karstedt complex.
46. The process according to claim 39, wherein the additive is
obtained by dispersing the inhibitor in a solution of the catalyst
in an unsaturated silane or siloxane, preferably vinylsiloxane.
47. The process according to claim 46, wherein the additive is
obtained by dispersing the inhibitor in a platinum/unsaturated
siloxane catalyst solution, in particular a platinum/vinylsiloxane
catalyst solution, preferably Karstedt solution.
48. The process according to claim 39, wherein the additive is
obtained by mixing the inhibitor in a silicone gum or oil at a
temperature greater than the melting temperature or softening
temperature of the inhibitor, followed by addition of the
catalyst.
49. A process for preparing a catalyst additive or assembly
comprising a metallic hydrosilylation catalyst and an
organophosphorus compound which inhibits the catalytic action of
the catalyst at room temperature, said process comprising adding
said organophosphorus compound to a silicone gum or oil and
dispersing said organophosphorus compound in said silicone gum or
oil at a temperature greater than the melting temperature or
softening temperature of said organophosphorus compound, and then
mixing said catalyst into the composition thus obtained.
50. The process according to claim 49, comprising first dispersing
said organophosphorus compound in said oil or gum and then heating
the resultant mixture to a temperature greater than the melting
temperature or softening temperature of the organophosphorus
compound.
51. The process according to claim 49, wherein the composition
formed from the silicone gum or oil and the organophosphorus
inhibitor is cooled, in particular at room temperature, prior to
mixing said composition with said catalyst.
52. A process for preparing a catalyst additive or assembly
comprising a metallic hydrosilylation catalyst and an
organophosphorus compound which inhibits the catalytic activity of
the catalyst at room temperature, comprising mixing a solution or
dispersion of said metal catalyst in an unsaturated silane or
siloxane, preferably vinylsiloxane, with said organophosphorus
compound.
53. The process according to claim 49, wherein the catalyst is a
platinum/unsaturated silane or platinum/unsaturated siloxane
solution, in particular a platinum/vinylsiloxane solution and
preferably a Karstedt solution.
54. The process according to claim 49, wherein the organophosphorus
compound is selected from organophosphorus compounds of formula
(I): ##STR17## in which: R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4,
which are identical or different, represent a linear, branched or
cyclic alkyl radical or an aryl radical which is substituted or
unsubstituted, especially: iv. a linear or branched alkyl radical
having particularly 2 to 30 carbon (C) atoms, preferably 2 to 12 C,
v. an alkyl radical containing one or more rings, especially 1 or
2, it being possible in particular for one ring to have 4 to 14 C,
preferably 5 to 8 C, or vi. an aryl or alkylaryl radical containing
one or more fused or unfused aromatic rings, especially 1 or 2
rings, it being possible for one ring to contain 4 to 14 C,
preferably 6 to 8 C, which is or are optionally substituted by 1 or
more, especially 1 to 2, linear or branched alkyl(s), especially
having 1 to 12 C, preferably 4 to 12 C, or wherein the inhibitor is
of the formula (VIII) P(OR).sub.3 in which R is an alkylaryl
radical having in particular 7 to 31 carbon atoms, preferably
substituted phenyl radicals.
55. The process according to claim 54, wherein the inhibitor is of
the following formula (IX): ##STR18## in which R.sup.1, R.sup.2,
R.sup.3, R.sup.4 and R.sup.5, which are identical or different,
represent H, a linear or branched aliphatic radical, saturated, of
formula C.sub.nH.sub.2n+1, or unsaturated, of formula
C.sub.mH.sub.2m-1, or a radical of formula C.sub.nF.sub.2n+1, with
n=1 to 15 and m=3 to 15, it not being possible for all of these
radicals together to represent H.
56. The process according to claim 54, wherein the inhibitor is of
the following formula (X): ##STR19##
57. An additive comprising a hydrosilylation catalyst and an
organophosphorus compound which inhibits the catalytic action of
the catalyst at room temperature, obtainable by the process
according to claim 49.
58. A catalyst assembly comprising, in an organosilicone solvent
such as an unsaturated silane, an unsaturated siloxane, a silicone
oil or a silicone gum, a metal catalyst capable of catalyzing a
hydrosilylation reaction and an inhibitor of the following formula
(I): ##STR20## in which: R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4,
which are identical or different, represent a linear, branched or
cyclic alkyl radical or an aryl radical which is substituted or
unsubstituted, especially: i. a linear or branched alkyl radical
having particularly 2 to 30 carbon (C) atoms, preferably 2 to 12 C,
ii. an alkyl radical containing one or more rings, especially 1 or
2, it being possible in particular for one ring to have 4 to 14 C,
preferably 5 to 8 C, or iii. an aryl or alkylaryl radical
containing one or more fused or unfused aromatic rings, especially
1 or 2 rings, it being possible for one ring to contain 4 to 14 C,
preferably 6 to 8 C, which is or are optionally substituted by 1 or
more, especially 1 to 2, linear or branched alkyl(s), especially
having 1 to 12 C, preferably 4 to 12 C, wherein the inhibitor
inhibits the catalytic action of the catalyst at room
temperature.
59. The catalyst assembly according to claim 58, wherein R is a
cyclic alkyl radical or an aryl radical, preferably biphenyl.
60. The catalyst assembly according to claim 58, wherein R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 are cyclic alkyl radicals, aryl
radicals or alkylaryl radicals, preferably substituted phenyl
radicals.
61. The catalyst assembly according to claim 58, wherein the
inhibitor is of the formula (II): ##STR21## in which the radicals
R.sup.5, which are identical or different, preferably identical,
are linear or branched alkyls having in particular 1 to 12 C,
preferably 4 to 12 C.
62. The catalyst assembly according to claim 58, wherein the
inhibitor is of the formula (III): ##STR22##
63. The catalyst assembly according to claim 58, wherein the molar
ratios of the metal catalyst to inhibitor are between 1/0.5 and
1/10, preferably between 1/1 and 1/5.
64. The catalyst assembly according to claim 58, wherein the metal
catalyst is a platinum catalyst.
65. The catalyst assembly according to claim 64, wherein the metal
catalyst is a platinum/unsaturated siloxane complex, preferably a
platinum/vinylsiloxane complex.
66. The catalyst assembly according to claim 64, wherein the metal
catalyst is a Karstedt complex.
67. A catalyst assembly comprising the following chemical species:
##STR23## in which: R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4, which
are identical or different, represent a linear, branched or cyclic
alkyl radical or an aryl radical which is substituted or
unsubstituted, especially: iv. a linear or branched alkyl radical
having particularly 2 to 30 carbon (C) atoms, preferably 2 to 12 C,
v. an alkyl radical containing one or more rings, especially 1 or
2, it being possible in particular for one ring to have 4 to 14 C,
preferably 5 to 8 C, or vi. an aryl or alkylaryl radical containing
one or more fused or unfused aromatic rings, especially 1 or 2
rings, it being possible for one ring to contain 4 to 14 C,
preferably 6 to 8 C, which is or are optionally substituted by 1 or
more, especially 1 to 2, linear or branched alkyl(s), especially
having 1 to 12 C, preferably 4 to 12 C.
68. A catalyst assembly comprising the following chemical species:
##STR24## in which the radicals R.sup.5, which are identical or
different, preferably identical, are linear or branched alkyls,
having in particular 1 to 12 C, preferably 4 to 12 C.
69. A catalyst assembly comprising the following chemical species:
##STR25##
70. A hydrosilylation-crosslinkable silicone composition comprising
at least one polyorganosiloxane (POS) A bearing ethylenic and/or
acetylenic unsaturation(s), at least one polyorganohydrosiloxane
(POS) B, a hydrosilylation catalyst and an inhibitor of formula
(I): ##STR26## in which: R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4,
which are identical or different, represent a linear, branched or
cyclic alkyl radical or an aryl radical which is substituted or
unsubstituted, especially: vii. a linear or branched alkyl radical
having particularly 2 to 30 carbon (C) atoms, preferably 2 to 12 C,
viii. an alkyl radical containing one or more rings, especially 1
or 2, it being possible in particular for one ring to have 4 to 14
C, preferably 5 to 8 C, or ix. an aryl or alkylaryl radical
containing one or more fused or unfused aromatic rings, especially
1 or 2 rings, it being possible for one ring to contain 4 to 14 C,
preferably 6 to 8 C, which is or are optionally substituted by 1 or
more, especially 1 to 2, linear or branched alkyl(s), especially
having 1 to 12 C, preferably 4 to 12 C.
71. The composition according to claim 70, wherein the silicone
composition is of the high-temperature-vulcanizable composition
type or of the room-temperature-vulcanizable type.
72. The composition according to claim 70, wherein the POS A has a
viscosity of at least 5.times.10.sup.5 mPa.s, preferably between
1.times.10.sup.6 and 1.times.10.sup.7 mPa.s, at 25.degree. C.
73. The composition according to claim 70, wherein the POS A has a
viscosity of between 1.times.10.sup.4 and 5.times.10.sup.5
mPa.s.
74. The composition according to claim 70, wherein the POS A has a
viscosity of between 100 and 10.sup.4 mpa.s, preferably between
1000 and 5000 mPa.s, at 25.degree. C.
75. The composition according to claim 70, wherein the POS B has a
viscosity of between 10 and 10 000 mpa.s, preferably between 50 and
1000 mPa.s, at 25.degree. C.
Description
[0001] The invention relates to new inhibitors of catalysts of
hydrosilylation reactions that involve polyorganosiloxanes (POS)
bearing Si--H units and POS bearing ethylenic and/or acetylenic
unsaturation(s), referred to hereinafter as POS bearing
Si-[ethylenic or acetylenic unsaturation] units, and to the
catalyst assemblies obtained from the mixture of these inhibitors
and catalysts. The invention also pertains to one-component
silicone compositions which crosslink by way of hydrosilylation
reactions and comprise such an inhibitor or catalyst assembly.
[0002] The invention likewise relates to particular methods of
employing hydrosilylation catalyst inhibitors, to processes for
preparing mixtures of inhibitors and catalysts, to processes for
preparing one-component silicone compositions and to the
compositions obtainable by employing these processes.
[0003] Hydrosilylation reactions allowing silicones to crosslink
are conventionally catalysed by platinum catalysts (U.S. Pat. No.
2,823,218, U.S. Pat. No. 2,970,150). In practice the majority of
industrial hydrosilylation reactions have to date been catalysed by
Karstedt solution, which is composed of complexes of platinum in
oxidation state 0 (U.S. Pat. No. 3,775,452 and U.S. Pat. No.
3,715,334). The ideal general formula of the Karstedt complex is
Pt.sub.2(tetramethyldivinylsiloxane).sub.3: ##STR2## where Me
represents methyl.
[0004] The Karstedt complex can be prepared by contacting
1,3-divinyl-tetramethyldisiloxane with chloroplatinic acid
(H.sub.2PtCl.sub.6), in the presence of NaHCO.sub.3 and an
aqueous-alcoholic solvent (e.g. isopropanol).
[0005] The very high catalytic activity of this type of catalyst,
even at room temperature, is a major drawback in the context of its
use in polyaddition HTV elastomers, since the crosslinking of the
elastomer begins as soon as the components are contacted with one
another.
[0006] More stable metallic Pt/carbene complexes have been
proposed. Thus, FR-A-2 801 887 discloses metal complexes useful as
hydrosilylation catalysts, of formula: ##STR3## in which: [0007]
R.sub.3 represents a hydrogen atom; a (C.sub.1-C.sub.8)alkyl group;
or a (C.sub.3-C.sub.8)cycloalkyl group optionally substituted by
(C.sub.1-C.sub.4)alkyl; [0008] T.sub.1 and T.sub.2 are identical
and represent (C.sub.1-C.sub.8)alkyl or
(C.sub.3-C.sub.8)cycloalkyl; [0009] R.sub.d and R.sub.e are
identical and represent (C.sub.1-C.sub.8)alkyl or
(C.sub.3-C.sub.8)cycloalkyl; (preferably
T.sub.1=T.sub.2=R.sub.d=R.sub.e=methyl).
[0010] Conventionally, in order to increase the room-temperature
storage stability (pot life) of one-component silicone compositions
which can be crosslinked by hydrosilylation reaction, use is made
of crosslinking inhibitors which act by masking the activity of the
catalyst at room temperature. The activity of the catalyst is
restored when the temperature is raised. Organophosphorus compounds
have been proposed.
[0011] Thus U.S. Pat. No. 3,188,300 describes the use of various
phosphine or phosphite ligands of formula: ##STR4## in which
R.sup.1, R.sup.2 and R.sup.3, which are identical or different, are
alkyl, aryl, aralkyl, alkaryl, alkoxy, aryloxy, aralkoxy or
alkaryloxy radicals.
[0012] U.S. Pat. No. 5,380,812 proposes di- and
trihydrocarbylphosphines, di- and trihydrocarbylphosphine oxides,
di- and triorganophosphites of formula
(R.sup.1O--).sub.aH.sub.(3-a)P and phospholene oxides. In the above
formula R.sup.1 is a substituted or unsubstituted monovalent
hydrocarbon radical, for example alkyl, aralkyl or alkaryl, and a
is 2 or 3.
[0013] Mention may also be made of U.S. Pat. No. 4,593,084, U.S.
Pat. No. 5,654,455 and U.S. Pat. No. 6,300,455. The latter
describes phosphite ligands of formula P(OR).sub.3 in which R is a
C.sub.7-C.sub.31 radical or an alkylaryl radical. Preferred ligands
are of formula: ##STR5##
[0014] The phosphines make it possible to inhibit the platinum
instantaneously, but their affinity for platinum is such that the
catalyst system finally obtained exhibits mediocre reactivity.
Phosphites present a more advantageous trade-off between inhibition
and reactivity.
[0015] Beyond the selection of an inhibitor/catalyst pairing, the
properties of the catalyst systems may depend on the conditions
under which they are employed and on the dispersion of the
inhibitor/catalyst pairing in the silicone material.
[0016] In U.S. Pat. No. 6,300,455 the organophosphorus inhibitor
(compound d) is added to the vinylsilicone oil (compound a) before
the hydrosilylation catalyst (compound c) is added, and then the
polyhydrosiloxane (compound b) is added in its turn.
[0017] However, generally speaking, organophosphorus compounds are
soluble only sparingly, if at all, in silicone oils, which tends to
give rise to poor dispersion of these compounds. The result is that
the complexation of the platinum, and hence its inhibition, may
take a long time to be obtained with such a method, which therefore
opens up the risk of a non-optimum homogeneity and of premature
crosslinking of the end composition.
[0018] It would be advantageous to have inhibitors which allow a
high inhibitory power to be combined with an effective catalytic
activity, and which make it possible to prepare one-component
compositions having a satisfactory pot life, e.g. of from 1 day to
several months. It would also be advantageous to have methods of
employing these inhibitors/catalysts which are highly
effective.
[0019] The objective of the present invention is therefore to
respond to this need by providing new inhibitors and more
particularly a new catalyst assembly comprising a catalyst and an
inhibitor, the catalytic activity being inhibited (undetectable) at
room temperature.
[0020] Another objective of the invention is to provide methods of
employing inhibitor/catalyst pairings which make it possible to
ensure, under the best of conditions, catalyst/inhibitor coupling
and/or dispersion of the catalyst, the inhibitor and the catalyst
assemblies in a silicone composition.
[0021] Yet another objective of the invention is to provide
catalyst assemblies exhibiting enhanced ease of use, particularly
for their mixing with silicone compositions.
[0022] Another objective, additionally, of the invention is to
provide a silicone composition which is crosslinkable by
hydrosilylation and comprises as catalyst a catalyst assembly of
this kind having inhibited activity at room temperature, so as to
make it possible to produce one-component compositions, comprising
the catalyst and compounds capable of reacting at high temperature
by way of hydrosilylation of unsaturated units (e.g. SiH
POS/Si-alkenyl POS), while being stable at room temperature for
long periods (e.g. 1 day to several months).
[0023] The present invention accordingly provides a catalyst
composition or assembly comprising a metal catalyst capable of
catalysing a hydrosilylation reaction and an inhibitor of the
following formula (I): ##STR6## in which: [0024] R, R.sup.1,
R.sup.2, R.sup.3 and R.sup.4, which are identical or different,
represent a linear, branched or cyclic alkyl radical or an aryl
radical which is substituted or unsubstituted, especially: [0025] a
linear or branched alkyl radical having particularly 2 to 30 carbon
(C) atoms, preferably 2 to 12 C, [0026] an alkyl radical containing
one or more rings, especially 1 or 2, it being possible in
particular for one ring to have 4 to 14 C, preferably 5 to 8 C, or
[0027] an aryl or alkylaryl radical containing one or more fused or
unfused aromatic rings, especially 1 or 2 rings, it being possible
for one ring to contain 4 to 14 C, preferably 6 to 8 C, which is or
are optionally substituted by 1 or more, especially 1 to 2, linear
or branched alkyl(s), especially having 1 to 12 C, preferably 4 to
12 C, the inhibitor in the composition or assembly inhibiting the
catalytic action of the catalyst. In particular the catalytic
action is inhibited at room temperature but may be restored by
heating (e.g. between 50 and 200.degree. C., more particularly
between 100 and 150.degree. C.). In the composition or assembly,
inhibitor and catalyst are complexed. Without wishing to be bound
by a specific theory, it is thought that the complexation results
from interactions between P and Pt, as will be illustrated later
on. In the present invention the term "inhibition" embraces what is
known as complete inhibition, owing to the incorporation of a
sufficient amount of inhibitor (especially with 1 atom or,
preferably, more than 1 atom of phosphorus P per metal atom of the
catalyst). The term also embraces what is known as incomplete
inhibition, if the amount of inhibitor incorporated is
insufficient. In this latter case in particular, inhibition may be
completed by separate incorporation of the same kind of inhibitor
or by way of another inhibitor.
[0028] According to one preferred embodiment the composition
comprises as solvent an organosilicon compound, such as a silane, a
siloxane, a silicone oil and/or a silicone gum. The composition may
therefore comprise one or more unsaturated silanes and/or one or
more unsaturated siloxanes containing one or more siloxane units
(e.g. from 2 to 200, preferably from 2 to 30). The compounds in
question are preferably vinylsilanes and/or vinylsiloxanes. Further
details regarding their nature will be given later on. The silanes
and siloxanes described in U.S. Pat. No. 3,775,452 and U.S. Pat.
No. 3,715,334, which are referred to later on, are possible
versions. The composition may further comprise one or more silicone
oils or gums such as those which are described later on, and which
embrace alkenyl types, especially vinyl types, and other types
(e.g. based on units of the formula (V), which is defined later
on).
[0029] According to one particular version the invention relates to
a catalyst composition or assembly comprising, optionally in an
organosilicon solvent as described above, the metal catalyst
capable of catalysing a hydrosilylation reaction and an inhibitor
of formula (I) in which: [0030] R, R.sup.1, R.sup.2, R.sup.3 and
R.sup.4, which are identical or different, represent a linear,
branched or cyclic alkyl radical or an aryl radical which is
substituted or unsubstituted, especially: [0031] a linear or
branched alkyl radical having 2 to 30 carbon (C) atoms, preferably
2 to 12 C, [0032] an alkyl radical containing one or more rings,
especially 1 or 2, it being possible in particular for one ring to
have 4 to 14 C, preferably 5 to 8 C, or [0033] an aryl or alkylaryl
radical containing one or more fused or unfused aromatic rings,
especially 1 or 2 rings, it being possible for one ring to contain
4 to 14 C, preferably 6 to 8 C, which is or are optionally
substituted by 1 or more, especially 1 to 2, linear or branched
alkyl(s), especially having 1 to 12 C, preferably 4 to 12 C.
[0034] The text below applies to the various embodiments and
versions defined above. In the formula (I), R is advantageously a
cyclic alkyl radical and more preferably an aryl radical,
especially biphenyl.
[0035] R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are advantageously
cyclic alkyl radicals and more preferably aryl radicals, and more
preferably still alkylaryl radicals, especially substituted phenyl,
e.g. tert-butylphenyl. R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are
preferably identical.
[0036] As inhibitor, preference is given to compounds containing
cyclic alkyl or aryl radicals, owing to their inhibitory activity
lasting longer than that of the compounds containing linear or
branched alkyl radicals.
[0037] Preferred inhibitors are of the formula (II): ##STR7## in
which the radicals R.sup.5, which are identical or different,
preferably identical, are linear or branched alkyls having in
particular 1 to 12 C, preferably 4 to 12 C.
[0038] The preferred inhibitor is of the formula (III):
##STR8##
[0039] CAS No.: 38613-77-3.
[0040] The molar ratios of catalyst metal to inhibitor may be
between 1/0.5 and 1/10, preferably between 1/1 and 1/5.
[0041] The catalysts to which the invention relates include all
catalysts useful for hydrosilylating POS which bear Si--H units and
POS which bear Si-[ethylenic or acetylenic unsaturation] units. The
compounds in question may therefore be compounds of platinum, of
rhodium, or iridium, of nickel, of ruthenium and/or of palladium.
More particularly they are compounds of iridium or, more
preferably, of platinum.
[0042] The compound of platinum may be any complex of platinum and
an organic product, examples being those described in patents U.S.
Pat. No. 3,159,601, U.S. Pat. No. 3,159,602, U.S. Pat. No.
3,220,972 and European patents EP-A-0 057 459, EP-A-0 188 978 and
EP-A-0 190 530, or any complex of platinum and vinyl
organosiloxanes, examples being those described in patents U.S.
Pat. No. 3,419,593, U.S. Pat. No. 3,715,334, U.S. Pat. No.
3,377,432 and U.S. Pat. No. 3,814,730.
[0043] Mention may be made of chloroplatinic acid, an
alcohol-modified chloroplatinic acid or else a complex of
chloroplatinic acid with an olefin, an aldehyde or a vinylsiloxane,
among others. U.S. Pat. No. 2,823,218 discloses a chloroplatinic
acid hydrosilylation catalyst and patent U.S. Pat. No. 3,419,593
relates to catalysts formed by complexes of chloroplatinic acid and
vinylsiloxane-type organosilicone. Complexes of platinum and
hydrocarbons which are useful as a hydrosilylation catalyst are
disclosed by patents U.S. Pat. Nos. 3,159,601 and 3,159,602. U.S.
Pat. No. 3,723,497 describes a platinum acetylacetonate and patent
U.S. Pat. No. 3,220,972 provides catalysts based on platinum
alkoxide.
[0044] The invention relates more particularly to
platinum/unsaturated siloxane complexes, particularly
platinum/vinylsiloxane complexes, especially those obtained by
reacting a platinum halide with an unsaturated organosilicon
material such as an unsaturated silane or an unsaturated siloxane,
in accordance for example with the teaching of U.S. Pat. No.
3,775,452 and U.S. Pat. No. 3,715,334, to which the skilled person
may refer. The invention applies preferably to Karstedt solutions
or Karstedt complexes.
[0045] The catalyst assembly according to the invention comprises a
mixture of the catalyst and the inhibitor that leads to a new type
of complex species between these two compounds. Without wishing to
be bound to any specific theory, it is thought that, starting from
the Karstedt complex and an inhibitor of formula (I), the new
species (I') exhibits a structure of the following type: ##STR9##
where R, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have the same
meanings as for formula (I).
[0046] With the inhibitors of formula (II) and (III), without
wishing to be bound to any specific theory, it is thought that the
new species (II') and (III') have, respectively, the following
structures: ##STR10##
[0047] In formulae (I'), (II') and (III') the arrows represent the
interactions between the orbitals of the P and Pt atoms.
[0048] The present invention also provides: [0049] these new
species, [0050] the use of a compound of formula (I), especially
(II) and preferably (III), as an inhibitor of a metal catalyst,
especially a platinum catalyst, in particular a hydrosilylation
catalyst, especially in a one-component silicone composition which
crosslinks by way of hydrosilylation reaction, and [0051] the use
of mixtures of catalyst and inhibitor according to the invention,
and of these new species, as a catalyst in compositions catalysed
in particular by platinum, especially silicone compositions which
crosslink by way of hydrosilylation reactions, and more
particularly still the one-component compositions according to the
invention.
[0052] As explained elsewhere, the catalyst is inhibited by the
inhibitor at room temperature. Its activation may be brought about
by temperature increase.
[0053] Very advantageously the inhibitors according to the
invention, such as the inhibitors of formula (II) and (III), are
soluble in unsaturated silanes, especially vinyl silanes such as
vinyltrimethoxysilane (VTMO), and in unsaturated siloxanes,
examples being vinylsiloxanes, and in platinum/unsaturated silane
and platinum/unsaturated siloxane solutions, e.g.
platinum/vinylsiloxane solutions. This results in a greater ease of
use in the case of mixing with silicone oils. For preparing a
catalyst solution of this kind, the solution of catalyst and the
inhibitor can be mixed until the inhibitor dissolves completely.
Preferably the inhibitor is added to the catalyst solution.
[0054] In order to endow the one-component silicone compositions
with the best possible properties in terms of inhibition of the
hydrosilylation reaction and of controlled pot life, the applicant
has developed a specific production procedure. A catalyst assembly
or additive (or catalyst composition) in which catalyst and
inhibitor are present in complex form is prepared to start with.
The catalyst is therefore inhibited at room temperature. This
additive is intended for addition to the one-component silicone
composition under conditions which ensure fine and homogeneous
dispersion.
[0055] The present invention therefore likewise provides a process
for preparing a catalyst assembly or additive (or catalyst
composition) comprising an inhibitor/catalyst pairing. This process
applies to the inhibitors of formula (I) and their described
variants, and also to other effective organophosphorus compounds,
and especially to the inhibitors of general formula (VIII)
P(OR).sub.3, in which R is an alkylaryl radical having in
particular 7 to 31 carbon atoms, preferably substituted phenyl
radicals, substituted for example by linear or branched alkyls,
preferably identical, having in particular 1 to 12 C, preferably 4
to 12 C, for example t-Bu.
[0056] Among the compounds of formula (VIII), those of the formula
(IX) below are preferred: ##STR11## in which R.sup.1, R.sup.2,
R.sup.3, R.sup.4 and R.sup.5, which are identical or different,
represent H, a linear or branched aliphatic radical which is
saturated, of formula C.sub.nH.sub.2n+1, or unsaturated, of formula
C.sub.mH.sub.2m+1, or a radical of formula C.sub.nF.sub.2n+1, with
n=1 to 15, and m=3 to 15, it not being possible for all of these
radicals together to represent H. Preferably, R.sup.2, R.sup.4 and
R.sup.5 represent H and R.sup.1 and R.sup.3 represent aliphatic
radicals, preferably identical aliphatic radicals, e.g. t-Bu.
[0057] It is possible to calculate the amounts to be employed in
terms of the ratio of catalyst metal to inhibitor. For inhibitors
of type (I) this ratio may be between 1/0.5 and 1/10, preferably
between 1/1 and 1/5. For inhibitors of type (VIII) this ratio may
be between 1/1 and 1/10, preferably between 1/2 and 1/5.
[0058] According to one particular version at least one inhibitor
of formula (I) and at least one inhibitor of formula (VIII) are
used (for example, an inhibitor of formula (II), especially (III),
and an inhibitor of formula (IX)). The amounts of inhibitors may be
determined so as to maintain substantially the ratio P of
inhibitor/catalyst Pt resulting from the application of the ratios
set out above. For example, the respective amounts of the
inhibitors are selected so as to ensure a ratio of catalyst metal
to phosphorus of between 1/1 and 1/10.
[0059] In a first embodiment of the process of the invention
(embodiment 1 below) a solution comprising the catalyst and the
inhibitor is prepared by mixing the organophosphorus inhibitor into
the catalyst in solution in an unsaturated silane, e.g.
vinylsilane, or an unsaturated siloxane, preferably unsaturated
siloxane such as vinylsiloxane, e.g. in the platinum/unsaturated
siloxane solution, in particular in the platinum/vinylsiloxane
solution, preferably in the Karstedt solution. U.S. Pat. No.
3,775,452, to which the skilled person may refer, describes
unsaturated silanes and unsaturated siloxanes under the formulae
(1) and, respectively, (2) to (5). U.S. Pat. No. 3,715,334, to
which the skilled person may refer, describes vinylsilanes and
vinylsiloxanes under the formulae (1) and, respectively, (2) to
(5). The content of these US patents, and especially the
description of their formulae (1) to (5) describing silanes and
siloxanes highly suitable for the invention, is incorporated here
by reference.
[0060] As has been seen above, the inhibitors of formula (I),
especially the inhibitors of formula (II) and (III), are soluble in
unsaturated silanes and siloxanes, thereby allowing these
inhibitors to be dissolved quickly and easily in a catalyst
solution, especially a siloxane-type catalyst solution, e.g. in
Karstedt solution, and allowing rapid and effective inhibition of
the catalyst.
[0061] In the case of the inhibitors of formula (VIII), for example
(IX), which are not soluble, the inhibitor is merely dispersed in
the catalyst solution. The inhibition of the catalyst takes a
little bit longer to obtain.
[0062] Generally speaking the catalyst/inhibitor solution may
contain from 0.1% to 15%, preferably from 5% to 10%, by weight of
platinum metal. Mixing may be carried out by any conventional
stirring means, e.g., with a blade mixer.
[0063] Complexation, which is the formation in situ of the
inhibitor/catalyst complex, is very rapid, particularly of the
order of a few minutes.
[0064] In a second embodiment (embodiment 2 below) the process
comprises [0065] dispersing the organophosphorus inhibitor in a
silicone gum and/or oil, [0066] heating the silicone gum or oil to
a temperature greater than the melting or softening temperature of
the inhibitor, [0067] adding and mixing the catalyst.
[0068] The silicone gum or oil is heated to the appropriate
temperature before, during and/or after the addition of the
organophosphorus derivative. According to one preferred version the
organophosphorus compound is first dispersed in the oil or gum,
which is held at a temperature below the melting point, and then
the composition is heated to a temperature greater than the melting
or softening temperature of the organophosphorus compound.
[0069] The organophosphorus compound undergoes rapid, effective and
homogeneous dispersion in the silicone gum or oil. It is possible
in general to consider a dispersion time of more than a few
minutes, in particular of the order of 5 minutes to 1 hour,
preferably 15 minutes to 30 minutes, to be sufficient.
[0070] The silicone material is preferably heated to a temperature
greater by 1 to 50.degree. C., in particular from 5 to 20.degree.
C., more preferably 10 to 20.degree. C., above the melting or
softening temperature of the organophosphorus compound used. At the
selected temperature the mixture of silicone material and inhibitor
is kept stirring for a time sufficient to ensure effective melting
of the dispersed organophosphorus compound. It is possible in
general to consider a heating and stirring time of more than a few
minutes, in particular of the order of 5 minutes to 1 h, preferably
15 minutes to 30 minutes, to be sufficient.
[0071] The catalyst may then be added to the composition obtained
beforehand. In order to prevent the catalyst being denatured, if
necessary, the composition from before is cooled to a temperature
less than the denaturation point of the catalyst. Generally
speaking it is preferred to take the above composition to ambient
temperature, e.g. of the order of 25.degree. C.
[0072] According to one preferred version of this preparation
embodiment, after the above composition has cooled, especially to
room temperature, the Karstedt solution or complex is added and the
mixture is stirred.
[0073] Mixing is continued until the catalyst is homogeneously
dispersed in the silicone material and an inhibitor/catalyst
complex, generated in situ is formed, which notably is dispersed
finely and homogeneously in the silicone oil or gum.
[0074] The silicone oil or gum, or a mixture, used to form this
solution is selected so as to be compatible with the end silicone
composition. According to one preferred version an oil, gum or
mixture is used whose viscosity is close to or the same as that of
the end silicone composition or of the portion of the latter in
which the inhibitor/catalyst solution will first be mixed. In
particular it is possible to use an oil or gum which is identical
or nearly identical to one or more compounds of the end silicone
composition. Thus it is possible to use an oil or a gum containing
an alkenyl group (alkenylated), preferably a vinyl group, such as
the POS A according to the invention, and more preferably still the
POS A forming part of the one-component silicone composition
referred to. It is also possible to use a polyorganosiloxane gum or
oil C formed from siloxyl units, of the formula (V) defined later
on. The oil or gum in question may in particular be a
polydimethylsiloxane (PDMS) oil or gum. The viscosity of these
non-vinyl (non-alkenyl) oils or gums may range from a few mPa/s to
several millions of mPa/s, it being possible for the selection to
depend in particular on the type of end silicone composition, e.g.
RTV, LSR or HTV elastomer, to which the text below relates. The
mixing of the ingredients at the various stages is carried out by
means of a mixing device adapted to the viscosity of the oil or gum
used. For relatively high viscosities, as in the case of the oils
or gums used in HTV elastomers, it is possible to employ a roll
mill or an arm-type mixer.
[0075] In the two embodiments 1 and 2 it may be useful to add to
the composition that is obtained each time one or more ingredients
intended to facilitate mixing with the end silicone composition.
The facilitation in question may in particular involve adapting the
viscosity, in order to bring it closer to that of the constituent
or mixture of constituents of the end silicone material to which
the additive is added. The ingredient in question may in particular
be a silicone gum or oil having a viscosity which is compatible
with the POS A. Depending on the silicone composition, the skilled
person is perfectly capable of selecting an appropriate oil or gum,
appropriate particularly in terms of viscosity, to dilute the
inhibitor/catalyst composition obtained beforehand. According to
one particular version an oil or gum is employed which is selected
in particular from the above-defined oils or gums C, especially
PDMS, or else from the POS A described with reference to the
silicone composition.
[0076] The additive obtained in accordance with embodiment 1 or
embodiment 2, after possible dilution in an oil or gum, contains
preferably from 0.001% to 10%, more preferably from 0.01% to 1%, by
weight of platinum metal.
[0077] Preferably the additive thus obtained (embodiment 1 or 2) is
a simple paste intended for subsequent addition to the silicone
composition proper. In other words, this additive constitutes a
fraction of the final one-component silicone composition. According
to one advantageous embodiment the paste is based on one of the
constituents of this composition and in particular is based on the
POS A or based on PDMS.
[0078] The catalyst compositions or additives or assemblies
obtained by employing the preparation embodiments described above
are likewise provided by the present invention. They preferably
comprise at least one inhibitor of formula (I), (II), (III), (VIII)
or (IX) and a catalyst in accordance with the invention. According
to one first embodiment the catalyst composition comprises the
catalyst, the inhibitor and an unsaturated silane, or an
unsaturated siloxane, containing one or more siloxane units (e.g.
from 2 to 200, preferably from 2 to 30), in particular in
accordance with the teaching of patents U.S. Pat. No. 3,775,452 and
U.S. Pat. No. 3,715,334 referred to above. The compounds in
question are preferably vinylsilanes and/or vinylsiloxanes.
According to one particular arrangement the composition is obtained
from a platinum/unsaturated silane or platinum/unsaturated siloxane
solution, in particular a platinum/vinylsiloxane solution, obtained
especially by reacting a platinum halide and an unsaturated
organosilicon material such as an unsaturated silane or an
unsaturated siloxane, an example being the Karstedt solution or
complex.
[0079] According to a second embodiment the catalyst composition
comprises the catalyst, the inhibitor, a silicone oil or gum, and
optionally a silane or a siloxane as described above. The oil or
gum is preferably identical or similar to one or more compounds of
the end silicone composition. It is preferred to use an oil or a
gum containing an alkenyl group, preferably a vinyl oil or gum,
such as the POS A according to the invention, and more preferably
still the POS A forming part of the intended one-component silicone
composition. It is also possible to have a polyorganosiloxane gum
or oil C, e.g. a PDMS.
[0080] According to one first version the catalyst composition
comprises at least one inhibitor of formula (I), (II) or (III),
optionally in combination with an inhibitor of formula (VIII) or
(IX), and an oil or gum containing an alkenyl group, preferably a
vinyl oil or gum, preferably POS A, and/or a polyorganosiloxane oil
or gum C, preferably PDMS.
[0081] According to a second version the catalyst composition
comprises or is essentially composed of at least one inhibitor of
formula (VIII) or (IX) and a polyorganosiloxane gum or oil C,
preferably PDMS.
[0082] In the catalyst composition the inhibitor inhibits the
catalytic action of the catalyst at room temperature. In
particular, inhibitor and catalyst are in complexed form.
[0083] The invention particularly provides an additive of this kind
in which the assembly of catalyst+inhibitor represents from 0.001
to 40% by weight, preferably from 0.01 to 30%, more preferably from
0.1 to 20%.
[0084] The present invention additionally provides a silicone
composition which is crosslinkable by hydrosilylation and comprises
at least one PolyOrganoSiloxane (POS) A bearing ethylenic and/or
acetylenic unsaturation(s), at least one hydrogenated
polyorganosiloxane B (POS B below) and also (a) a hydrosilylation
catalyst and an inhibitor of formula (I), (II) or (III), or (b) a
catalyst assembly obtained as described above.
[0085] By definition, throughout the present description, when it
is said that a silicone composition or a catalyst additive or
assembly comprises such or such an inhibitor of formula (I), (II),
(III), (VIII) or (IX), the reference should be understood as being
to the free inhibitor, to the inhibitor complexed to the catalyst,
or to a mixture of these two species.
[0086] According to the preferred version of the invention the
composition comprises a catalyst additive or assembly according to
the invention, preferably brought into the form of a paste prepared
in accordance with one of the above-defined preparation embodiments
1 and 2.
[0087] In a less preferred variant, the catalyst and the inhibitor
are added separately to the silicone composition. In that case it
is preferable to add them to POS A or to a composition containing
POS A and one or more other ingredients, with the exception of POS
B. POS B is incorporated after thorough mixing of the POS A, the
catalyst and the inhibitor, and advantageously after a certain
latency time. For its incorporation the inhibitor may
advantageously be in solution in a vinylsiloxane.
[0088] The invention relates both to polyaddition silicone
compositions which are room-temperature-vulcanizable (RTV; their
crosslinking may be accelerated at high temperature) and to
high-temperature-vulcanizable (HTV) elastomers. They are well known
to the skilled person, who may refer, for example, to patents U.S.
Pat. No. 3,220,972, U.S. Pat. No. 3,284,406, U.S. Pat. No.
3,346,366, U.S. Pat. No. 3,697,473 and U.S. Pat. No. 4,340,730.
[0089] As is known per se, POS A may be formed in particular of
siloxyl units of formula: Y a .times. Z b .times. SiO ( 4 - a - b )
2 ( IV ) ##EQU1## in which Y is a C.sub.2-C.sub.6 alkenyl,
preferably vinyl, Z is a monovalent hydrocarbon group which does
not have any adverse effect on the activity of the catalyst, Z
being selected generally from alkyl groups having 1 to 8 carbon
atoms inclusive, such as methyl, ethyl, propyl and
3,3,3-trifluoropropyl groups, and aryl groups, such as xylyl, tolyl
and phenyl, a is 1 or 2, b is 0, 1 or 2 and a+b is between 1 and 3,
optionally all of the other units being units of average formula: Z
c .times. SiO 4 - c 2 ( V ) ##EQU2## in which Z has the same
meaning as above and c has a value of between 0 and 3.
[0090] As is known per se, POS B may be formed in particular of
siloxyl units of formula: H d .times. W e .times. SiO 4 - d - e 2 (
VI ) ##EQU3## in which W is a monovalent hydrocarbon group having
no adverse effect on the activity of the catalyst and meeting the
same definition as Z, d is 1 or 2, e is 0, 1 or 2, d+e has a value
of between 1 and 3, optionally all of the other units being units
of average formula: W g .times. SiO 4 - g 2 ( VII ) ##EQU4## in
which W has the same meaning as above and g has a value of between
0 and 3.
[0091] These POS A & B are for example, respectively, a
polyorganovinylsiloxane and a polyorganohydrosiloxane. The organic
substituents other than the reactive groups, vinyl and hydrogen,
are for example methyls or cyclohexyls. The hydrogens and vinyls
are borne by siloxyl units M=[R.sub.3SiO--] and/or
D=[--(R).sub.2SiO--] and/or T=[--(R)SiO--]. These hydrogen or vinyl
units M or D each contain, respectively, one or more Hs or vinyls,
preferably just one.
[0092] The number of SiH or SiVi units per molecule is preferably
greater than or equal to 2. This may in particular represent from
0.01% to 10% (preferably 0.1 to 2%) of vinyl by weight for POS A
and from 0.001% to 5% (preferably 0.05 to 2%) of hydrogen by weight
for POS B.
[0093] Appropriate POS B are polymethylhydrosiloxanes having
--Si(CH.sub.3).sub.3 end groups and polydimethylsiloxanes having
--Si(CH.sub.3).sub.2H end groups, methylhydrodimethylsiloxane
copolymers having --Si(CH.sub.3).sub.2H end groups,
methylhydromethyloctylsiloxane copolymers and
methylhydrocyclosiloxane polymers.
[0094] Generally speaking the POS A & B have an average
molecular mass of between 1.times.10.sup.2 and 1.times.10.sup.7
(g/mol).
[0095] For POS A, this embraces in particular, in terms of dynamic
viscosity at 25.degree. C.: [0096] in the case of silicone
compositions which are high-temperature-vulcanizable (HTV) by
polyaddition, POS A having in particular a viscosity of at least
5.times.10.sup.5 mPa.s, preferably between 1.times.10.sup.6 and
1.times.10.sup.7 mpa.s, and even more, [0097] in the case of
silicone compositions which are high-temperature-vulcanizable by
polyaddition and are of liquid silicone elastomer (LSR) type, POS A
having in particular a viscosity of preferably between
1.times.10.sup.4 and 5.times.10.sup.5 mpa.s, and [0098] in the case
of silicone compositions which are room-temperature-vulcanizable
(the vulcanization being accelerated at high temperature) by
polyaddition, or RTV compositions, POS A having in particular a
viscosity of between 100 and 10.sup.4 mpa.s, preferably between
1000 and 5000 mpa.s.
[0099] The POS B generally have a viscosity of between 10 and 10
000 mPa.s, preferably between 50 and 1000 mPa.s.
[0100] According to one preferred version of the invention the
silicone compositions concerned are POS which are
high-temperature-vulcanizable (HTV) by polyaddition and in which
the POS A may have in practice a viscosity at 25.degree. C. of, for
example, 1.times.10.sup.6 to 5.times.10.sup.6 mPa.s and the POS B a
viscosity at 25.degree. C. of 10 to 5000 mPa.s, in particular from
50 to 1000 mpa.s (e.g. 300 mPa.s).
[0101] The viscosity is measured using a BROOKFIELD viscometer as
indicated in the standard AFNOR NFT 76 106 of May 1982.
[0102] All of the viscosities referred to in the present
specification correspond to a magnitude of dynamic viscosity at
25.degree. C. which is referred to as "Newtonian"; that is, the
dynamic viscosity which is measured, in a manner known per se, at a
shear rate sufficiently low for the measured viscosity to be
independent of the shear rate.
[0103] According to one particular version of the invention the
silicone composition comprising the POS A and B and the catalyst
assembly according to the invention may be admixed with an
inhibitor of formula (I), (II) or (III), especially in solution in
a vinylsiloxane, and/or with another crosslinking inhibitor, of
formula (VIII) or (IX) for example, with an acetylenic alcohol
(FR-A-2 372 874, FR-A-1 528 464), with a maleate compound (U.S.
Pat. No. 4,256,870 and U.S. Pat. No. 4,530,989) or with an
acetylene dicarboxylate compound (U.S. Pat. No. 4,504,645 and U.S.
Pat. No. 4,347,346).
[0104] The silicone compositions of the invention may further
comprise customary functional additives. Classes of customary
functional additives may include: [0105] fillers, [0106]
hydroxylated POS oils which are useful as compatibilizers, [0107]
adhesion promoters, [0108] adhesion modifiers, [0109] thermal
stability additives, [0110] additives for increasing the
consistency, [0111] pigments, [0112] thermal stability additives,
oil resistance additives, flame retardant additives (for example
metal oxides).
[0113] The fillers optionally provided are preferably minerals.
They may in particular be siliceous.
[0114] Siliceous materials may act as a reinforcing or
semi-reinforcing filler.
[0115] Reinforcing siliceous fillers are selected from colloidal
silicas, pyrogenic silica powders and precipitated silica powders,
or mixtures thereof. These powders have an average particle size of
generally less than 0.1 .mu.m and a BET specific surface area of
more than 50 m.sup.2/g, preferably between 150 and 350
m.sup.2/g.
[0116] Semi-reinforcing siliceous fillers, such as diatomaceous
earths or ground quartz, may also be employed.
[0117] Nonsiliceous mineral materials may play a part as a
semi-reinforcing or bulking mineral filler. Examples of these
nonsiliceous fillers, which can be used alone or in a mixture, are
carbon black, titanium dioxide, aluminium oxide, hydrated alumina,
expanded vermiculite, unexpanded vermiculite, calcium carbonate,
zinc oxide, mica, talc, iron oxide, barium sulphate and slaked
lime. These fillers have a particle size of generally between 0.001
and 300 .mu.m and a BET surface area of less than 100
m.sup.2/g.
[0118] From a practical but non-limitative standpoint, the fillers
employed may be a mixture of quartz and silica.
[0119] The fillers may be treated with any appropriate product.
[0120] From a weight standpoint it is preferred to employ an amount
of filler of between 10% and 50% by weight, preferably between 20%
and 40% by weight, relative to the entirety of the constituents of
the composition.
[0121] More generally, from a quantitative standpoint, the
compositions according to the invention are in accordance with
standard proportions in the technical field under consideration,
bearing in mind that the intended application must also be taken
into account.
[0122] The invention further provides a process for preparing a
hydrosilylation-crosslinkable one-component silicone composition
comprising at least one polyorganosiloxane (POS) A bearing
ethylenic and/or acetylenic unsaturation(s), at least one
hydrogenated polyorganosiloxane B (POS B below), at least one
hydrosilylation catalyst and at least one inhibitor of formula (I),
(II), (III), (VIII) and/or (IX), in which process the inhibitor and
the catalyst are brought into the form of a catalyst additive or
assembly prepared beforehand according to the invention, preferably
a paste formed from the premixing of the inhibitor and the
catalyst. In other words the catalyst is introduced in its
inhibited form in combination with the inhibitor. In accordance
with what was described above, the inhibition may relate to all or
part of the catalyst molecules, depending on the amount of
inhibitor present in the additive. The inhibition is preferably
complete.
[0123] This additive may be brought into the rest of the silicone
composition or into any fraction thereof, especially into a
fraction comprising or consisting of POS A, POS B or a mixture of
POS A and B. The process may also be defined as incorporating the
production of the additive as described above and then the bringing
of this additive into the silicone composition.
[0124] According to one first embodiment of the invention an
additive prepared in accordance with embodiment 1 described above
(with or without dilution) is added. The additive is therefore
obtained from the dispersing of the inhibitor in a solution of the
catalyst in an unsaturated silane or siloxane, preferably
vinylsiloxane.
[0125] According to a second embodiment an additive prepared in
accordance with embodiment 2 described above (with or without
dilution) is added. In that case the additive is obtained from the
mixing of the inhibitor in a silicone gum or oil at a temperature
greater than the melting temperature or softening temperature of
the inhibitor, followed by addition of the catalyst.
[0126] The additive may be added before, during or after addition
of other ingredients, such as mineral filler, crosslinking
inhibitor, hydroxylated POS oil, or other, customary functional
additives such as those described above.
[0127] The catalyst additives or assemblies according to the
invention may be easily mixed into this silicone composition. The
various mixing means commonly employed in the silicone industry may
be used, and especially arm-type mixers and roll mills when
required by the viscosity, particularly in the case of HTV
elastomers. The mixing operation is continued to give optimum
dispersion of the catalyst additive or assembly. The skilled worker
is capable of determining the optimum conditions.
[0128] The invention additionally provides one-component silicone
compositions obtainable by employing the preparation process
described above, these compositions being characterized in
particular by remarkably fine and homogeneous dispersion of the
catalyst/inhibitor pairing.
[0129] Further provided by the invention is a process for
hydrosilylating one or more POS A using one or more POS B,
characterized in that it consists in employing a silicone
composition as defined above and in heating it to the crosslinking
temperature, generally between 50 and 200.degree. C., more
particularly between 100 and 150.degree. C. Depending on the
composition, the skilled person has no difficulty at all in
determining the optimum temperature for initiating the
hydrosilylation.
[0130] The relative amount of unsaturated compound and of compound
containing Si--H unit may be controlled so as to ensure that all of
the unsaturations react with Si--H bonds.
[0131] In general the molar ratio of the unsaturations to the Si--H
bonds varies between 1:10 and 10:1.
[0132] According to the invention the hydrosilylation reaction is
conducted in the presence of a catalytic amount of the catalyst
according to the invention. By catalytic amount is meant less than
one molar equivalent of platinum relative to the amount of
unsaturations present in the reaction mixture.
[0133] Generally speaking it is enough to introduce less than 1000
ppm, preferably less than 100 ppm, more preferably less than 50 ppm
of platinum into the reaction mixture, calculated relative to the
total mass of the unsaturated compound and of the compound
containing Si--H units.
[0134] The POS A & B, the catalyst, the compounds of formula
(I), (II), (III), (VIII) and (IX) and also the other, conventional
additives, such as the fillers, are very readily available products
accessible to the skilled person.
[0135] The compounds of formula (I), (II) or (III) may be obtained
conventionally by reacting (i) a dihalogen compound X-R-X (X being
a halogen atom), R being as defined above with respect to formulae
(I), (II) and (III), with (ii) an excess of PCl.sub.3, then by
reacting the compound obtained in the preceding stage with 4
molecules of alcohol R'OH, thereby making it possible to form the
groups R.sup.1 to R.sup.4 of formulae (I), (II) and (III). The
resulting product may then be purified using the conventional
techniques known to the skilled person. They may also be prepared
in accordance with the teaching of U.S. Pat. No. 5,109,043.
[0136] The invention will now be described with the aid of
non-limitative examples.
EXAMPLES
Example 1
Preparation of a Catalyst Solution Having an Inhibitor (III)/Pt
Ratio=0.75 (i.e. P/Pt=1.5)
[0137] 10 g of a Karstedt platinum solution containing 12.6% of Pt
by weight (6.46 mmol of platinum) are placed in a flask equipped
with a magnetic stirrer.
[0138] 5.01 g (4.85 mmol or 0.75 equivalent) of inhibitor (III)
according to the invention are added to the above solution with
stirring.
[0139] Following the addition the reaction mixture is kept with
stirring for a few minutes. A catalyst solution is obtained which
contains 8.4% of platinum by weight. This clear, homogeneous,
readily manipulable solution is used in the following examples.
[0140] NMR analysis of this reaction mixture shows the complete
disappearance of the Karstedt catalyst.
Example 2
Preparation of a Catalyst Assembly Having an Inhibitor (IV)/Pt
ratio=1.5 (i.e. P/Pt=1.5)
[0141] 10 g of a Karstedt platinum solution containing 12.6% of Pt
by weight (6.46 mmol of platinum) are placed in a flask equipped
with a magnetic stirrer. 6.27 g (9.69 mmol or 1.5 equivalent) of an
inhibitor according to U.S. Pat. No. 6,300,455 are added to the
above solution with stirring. This inhibitor, of formula (IX)
above, conforms more specifically to the formula (X) below:
##STR12##
[0142] Following the addition the reaction mixture is
heterogeneous. It remains heterogeneous even after several minutes
of stirring. After 3 h of stirring the reaction mixture becomes
heterogeneous and white in colour. Stopping the stirring causes the
white solid to decant to the bottom of the flask.
[0143] NMR analysis of this reaction mixture shows the complete
disappearance of the Karstedt catalyst.
Example 3
Composition According to the Invention (All Parts Are Given by
Weight).
[0144] A/Preparation
[0145] In a Z-arm mill an HTV base 1 is prepared by mixing the
following for 2 hours at room temperature (23.degree. C.): [0146]
100 parts of a vinyl-containing polydimethylorganosiloxane
containing 720 ppm of groups Vi in the chain and having a viscosity
of 5 million mPa.s at 25.degree. C., [0147] 33 parts of
surface-treated pyrogenic silica with a specific surface area of 60
m.sup.2/g, [0148] 13 parts of an untreated silica with a specific
surface area of 150 m.sup.2/g and [0149] 6 parts of a
compatibilizing agent, which is a hydroxyl-containing
polyorganosiloxane oil. The following components are added to this
preparation on rolls: [0150] 0.604 part of a
polydimethylorganosiloxane oil containing 30% by weight of --SiH
groups and having a viscosity of 30 mpa.s at 25.degree. C. [0151]
2.5 ppm of platinum metal, brought into the form of the catalyst
assembly of Example 1. [0152] 6.25 ppm of inhibitor (III) in
solution in a vinylsiloxane.
[0153] B/Characterization of the Composition: [0154] One fraction
of the homogeneous mass obtained is used for measuring the
rheometric properties of the silicone elastomer in the course of
vulcanization of the polyorganosiloxane composition at 140.degree.
C. [0155] This characterization is conducted in accordance with
standards NF T43015 and ISO 6502. A specimen of catalysed elastomer
is compressed in an airtight chamber under a given pressure and at
a given temperature. The chamber is formed from two half-chambers,
one of which is subjected to linear or rotational (disc)
oscillations of low amplitude. This action produces in the specimen
an alternative sinusoidal deformation, linear or in torsion, and a
sinusoidal shearing torque or force which depend on the stiffness
(shear modulus) of the elastomer. The stiffness of the specimen
increases in line with the vulcanization or polyaddition reaction.
Measuring the torque required for the oscillation of the disc over
time makes it possible to obtain, at the end of measurement, the
vulcanization characteristics of the elastomer. Rheometric
properties recorded at 140.degree. C.: [0156] ts2: scorch time
(Cmin+2 points), corresponding to the vulcanization time [0157]
t50: time required to obtain 50% of the value of Cmax [0158] t90:
time required to obtain 90% of the value of Cmax [0159] Cmin:
minimum elastic torque applied (also called S'mini) [0160] Cmax:
maximum elastic torque applied (also called S'maxi)
[0161] Vmax: maximum vulcanization rate attained. TABLE-US-00001
Characteristics Values ts2 20 s t50 47 s t90 389 s Cmin 1 dNm Cmax
10.7 dNm Vmax 12.6 dNm/min
Pot life
[0162] After 4 weeks of ageing at room temperature the mixture has
still not crosslinked.
[0163] The entirety of these results shows that the novel catalyst
assembly claimed is characterized by great ease of use and by
high-performance catalyst properties (as measured by
rheometry).
Example 4
Preparation In Situ, by a High-temperature Process, of an Additive
Based on a Silicone Matrix, Karstedt Platinum and Inhibitor
(III)
[0164] 4a/ In an arm-type mixer, 0.261 g of inhibitor (III) is
added to 100 g of an HTV base 2 with a hardness of 35. After mixing
for 10 minutes, the temperature of the reaction mixture is raised
to at least 100.degree. C., a temperature higher than the softening
temperature--75-95.degree. C.--of inhibitor (III). After mixing for
10 minutes, the reaction mixture is allowed to cool to 25.degree.
C. Observation of the mixture does not reveal the presence of
agglomerates in the elastomer matrix.
[0165] 4b/ Subsequently, either on a roll mill or in an arm-type
mixer, 0.375 g of Karstedt catalyst is added (platinum in oxidation
state zero in solution in a vinylsilicone oil) (10% by mass of
platinum).
[0166] Note: for all of Examples 4 to 10 an HTV base 2 was used
which was composed of: [0167] 50 parts of vinyl-containing
polydimethylorganosiloxane containing 720 ppm of vinyl groups in
the chain and having a viscosity of 5 million mPa.s at 25.degree.
C., [0168] 50 parts of vinyl-containing polydimethylorganosiloxane
containing 120 ppm of vinyl groups in the chain and having a
viscosity of 5 million mPa.s at 25.degree. C., [0169] 30 parts of
surface-treated pyrogenic silica with a specific surface area of 55
m.sup.2/g, and [0170] 1.22 parts of a compatibilizing agent, which
is a hydroxyl-containing polyorganosiloxane oil.
Comparative Example 5
Preparation on a Roll Mill, by a Cold Process, of an Additive Based
on a Silicone Matrix, Karstedt Platinum and Inhibitor (III)
[0171] On a roll mill 1.305 g of inhibitor (III) as a powder are
added to 500 g of the HTV base 2 with a hardness of 35. Following
incorporation, 1.875 g of Karstedt catalyst are added dropwise.
Comparative Example 6
Preparation in an Arm-type Mixer, by a Cold Process, of an Additive
Based on a Silicone Matrix, Karstedt Platinum and Inhibitor
(III)
[0172] The same type of additive described in Example 5 was
produced using an arm-type mixer.
[0173] 6a/ 1.048 g of inhibitor as a powder are added to 400 g of
the HTV base 2 with a hardness of 35. Mixing is continued for 20
minutes.
[0174] 6b/ 1.5 g of Karstedt catalyst are subsequently added to the
reaction mixture.
Examples 7 and 8
Evaluation of the Various Additives Prepared According to Examples
4 and 6
[0175] The various additives described in Examples 4 and 6 were
tested in an HTV formulation for the one-component polyaddition
application.
[0176] The composition of this HTV formulation is as follows: 100 g
of an HTV base 1 according to Example 3 is admixed using a roll
mill with 0.94 part of --SiH-containing oil (440 meq --SiH/100 g of
oil, viscosity 250 mPa.s). Following incorporation, and then after
15 passes between the two rolls (improving the dispersion of the
additives), 0.037 part of an additive composed of the HTV base 2
with a hardness of 35 and of inhibitor (III) according to Examples
4a and 6a is added. Following incorporation, and then 15 passes of
the composition between the two rolls, 0.267 part of the additive
composed of the HTV base, inhibitor (III) and Karstedt platinum
(Examples 4 and 6 above) is added. The amount of platinum is 1 ppm.
15 passes between the two rolls are also carried out. The results
in terms of uncured appearance of the formulations produced,
kinetic characteristics and changes in the formulation after 3
months at 25.degree. C. are reported in Table 2.
Example 9
Stability of the Additives Prepared According to Example 4
[0177] In order to follow the stability of these additives and the
kinetics of complexation between the Karstedt platinum, the
additives prepared according to Example 4 were evaluated over time.
Via an HTV formulation for the one-component polyaddition
application, identical to that described in Example 7, the
complexation of the platinum by the inhibitor and the stability of
this additive were monitored by way of measurements determined by
rheometry (Table 3).
[0178] Discussion of the Results Obtained with Examples 4 to 9
[0179] The additives prepared cold from inhibitor (III) and the
Karstedt platinum (Examples 5 and 6) contain agglomerates whose
average diameters vary depending on the type of tool employed
(Table 1). This means that these additives are not as highly
performing as the additive prepared at high temperature according
to Example 4 (Table 2). These additized one-component HTV
formulations according to Examples 5 and 6, however, remain stable
after three months of ageing.
[0180] For the additive prepared according to Example 4 no problem
caused by the incorporation of the inhibitor and then of the
Karstedt platinum is noted. The uncured additive is homogeneous. It
exhibits no defects (Table 1). The one-component HTV formulation
additized with these additives is stable after 3 months of ageing,
and no change is observed in the quality of the mouldings (Table
2). Rheometric monitoring of the complexation between the inhibitor
and the Karstedt platinum shows that this complexation is extremely
rapid. The values obtained on day 0 are of the same order as those
obtained after 18 days. Moreover, the values over this period are
homogeneous, indicating the stability of the additive (Table
3).
CONCLUSION
[0181] Employing the high-temperature process allows additives to
be obtained whose active species are very well dispersed. The high
quality of these additives goes hand in hand with the high quality
and stability of the final one-component HTV formulations.
TABLE-US-00002 TABLE 1 Characteristics, in the uncured state, of
the additives produced Example 4 5 6 System Inhibitor (III),
Karstedt platinum Preparation Employed Arm-type Roll mill Arm-type
of the mixer mixer additive Incor- No No problem No problem
poration problem phase Appearance of the additive Homo-
Heterogeneous, Hererogeneous, after preparation geneous
agglomerates agglomerates with a diameter with a diameter of 0.5 to
of 0.3 to 0.8 mm 0.5 mm
[0182] TABLE-US-00003 TABLE 2 Characteristics of the one-component
HTV formulations according to the examples Example 7 8 Additive
utilized Example 4 Example 6 Characteristics Inhibitor (III),
Inhibitor (III), Karstedt platinum Karstedt platinum Arm-type mixer
Arm-type mixer Appearance of the mouldings after No defects,
Under-crosslinked curing for 8 min at 140.degree. C. homogeneous
areas, presence of gels Rheological ts2 30 30 characteristics t50
52 55 t90 428 438 Cmin 1.59 1.82 Cmax 9.15 9.02 Vmax 8.2 7.1
Changes in the formulation in the Effective Effective uncured state
after 3 months replastification replastification
[0183] TABLE-US-00004 TABLE 3 Changes in the additive prepared
according to Example 4 Evaluation of the corresponding
one-component HTV formulations Age of the additive of Example 4 0 d
1 d 2 d 5 d 6 d 18 d ts 2 (sec.) 24 25 24 23 25 26 t50 (sec.) 53 51
46 46 57 54 t90 (sec.) 412 426 411 403 439 410 Cmin (dNm) 1.04 0.99
0.97 0.93 0.97 1.02 Cmax (dNm) 8.46 7.88 7.47 7.70 8.02 8.20 Vmax
8.6 8.8 7.47 7.70 8.02 8.3 (dNm/Min)
Example 10
Preparation of Catalyst/Inhibitor (III) or (X) Complexes
[0184] Catalyst 1:
[0185] 3.6 g of Karstedt catalyst at a concentration of 12% by
weight of platinum in divinyltetramethyldisiloxane (DVTMS) are
admixed by spatula and with vigorous magnetic stirring with 1.32 g
of compound (III) (so that the P/Pt molar ratio=1.2). After a few
minutes a homogeneous and readily manipulable fluid solution (C1)
is obtained. It contains 7.65% of platinum by weight and is used
directly in the examples which follow.
[0186] Catalyst 2:
[0187] 4.3 g of Karstedt catalyst at a concentration of 10% by
weight of platinum in DVTMS is admixed by spatula and with magnetic
stirring with 1.7 g of compound (X) (so that the P/Pt molar
ratio=1.2). After a few minutes a heterogeneous reaction mixture
(C2) is obtained. It contains 7.2% of platinum by weight and is
used directly in the examples which follow.
Example 11
Evaluation of the Quality of Inhibition Provided by C1 and C2
[0188] A reaction system is prepared by mixing 20 grams of an
organovinylpolysiloxane having a viscosity of 230 mpa.s and
containing 0.61% of vinyls by weight with the catalyst mixture C1
or C2 so as to give 80 ppm by weight of platinum in the final
mixture; subsequently 5.4 grams of an organohydrosiloxane having a
viscosity of 300 mPa.s and containing 0.17% by weight of hydrogen
are added. This final reaction mixture is homogenized by stirring
for 5 minutes.
[0189] To assess the quality of the inhibition, the gel time
t.sub.gel, corresponding to the time for the reaction mixture to
set, is measured at room temperature. The comparative reactivity of
the two systems is evaluated by DSC (Differential Scanning
Calorimetry). TABLE-US-00005 Catalyst DSC mixture t.sub.gel
t.sub.peak (.degree. C.) t.sub.endset - t.sub.onset(.degree. C.)
.DELTA.H.degree.(kJ/mol) C1 >24 hours 104 12 20.7 C2 >24
hours 109 19 20.4
Comparative Example 12
[0190] A reaction system is prepared by mixing 20 grams of an
organovinylpolysiloxane having a viscosity of 230 mpa.s and
containing 0.61% of vinyl by weight, the amount of organophosphorus
inhibitor (III) or (X) required to give a P/Pt ratio of 1.2, then
the Karstedt catalyst (14.3% solution of platinum in DVTMS) so as
to give 80 ppm by weight of platinum in the final mixture. This
mixture is stirred for 10 minutes at room temperature and then 5.4
grams of an organohydrosiloxane having a viscosity of 300 mPa.s and
containing 0.17% by weight of hydrogen are added. This final
reaction mixture is homogenized by stirring for a few minutes.
[0191] To assess the quality of the inhibition, the gel time,
corresponding to the time taken for the reaction mixture to set, is
measured at room temperature. TABLE-US-00006 Inhibitor t.sub.gel
(III) <5 minutes (X) <5 minutes
[0192] Examples 11 and 12 show that: [0193] to obtain
high-performance inhibition it is preferable to incorporate the
platinum in a pre-complexed form rather than to carry out this
complexation directly in the final reaction mixture. [0194] The
inhibitor of type (III) gives homogeneous catalyst systems in
DVTMS, which greatly facilitates their use. [0195] The reactivities
of the two catalyst systems are comparable.
[0196] It should be well understood that the invention defined by
the attached claims is not limited to the specific embodiments
indicated in the above description but embraces the variants
thereof which are not outside either the scope or the spirit of the
present invention.
* * * * *