Note: Descriptions are shown in the official language in which they were submitted.
' Le A 31 2$6-Eiorei~n Cr~lln~rieal Bs /ngb/S-P 2 1 ~ ~ 4 ~ 1
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Cl~ kq~ mixtures, a method of nre~arin~ them and their use
The present invention relates to crosslinkable mixtures, to a method of preparing
5 them and to thei} use.
The use of silicones for the adhesive coating of substrates such as paper, plastics
or metal foils, for example, i.e. for coatings which repel adhesive substances, has
been hnown for some time. In this connection, a liquid mixture comprising a
vinyl-containing polydiorganosiloxane, an Si-H-containing polydiorgqnr~eiloYqn~
10 (polyhydrogensiloxane) and a suitable catalyst is applied to the paper and is cured
at elevated Lt~ rldLulu~ by what is termed a hydrosilylation reaction (addition-u~u~ hillg systems). A solid silicone layer which adheres to the substrate is
formed in the course of this procedure. The silicone layer is applied to the
substrate via rollers, which take up the liquid, reactive silicone mixture from a vat
15 and transfer it to the substrate. If a substrate coating machine such as this breaks
down for an extended period of time for technical reasons, the silicone film is
capable of crosslinhing on the rollers even at room Ltlllp~,.a~ul~. This results in
silicone residues on the rollers which are extremely difficult to remove, and which
make it impossible to achieve trouble-free operation again aRer the machine has
20 been re-started.
Since problems which are similar in principle also arise in other applications of
addition-crosslinhing silicone systems (e.g. lLS~), numerous additives (inhibitors)
have been developed in the past, the function of all of which is to keep the
reactive mixtures liquid for longer at }oom ~tUll~ldLUlt:. Thus US-A-4 329 275,
25 for example, discloses the use of phosphorus compounds in combination with
peroxides as worhing life extenders. However, the addition of peroxides is
associated with safety risks during the production and processing of mixtures ofthis type. US-A-4 645 815 relates to the use of cyclometallized Pt phosphite
complexes. In this disclosure the catalyst complex is produced in a separate step,
30 which is associated with additional costs. However, both of the aforementioned
possible solutions have a further, very senous disadvantage. They were developedfor systems which employ relatively low concentrations of catalyst (10 ppm).
Silicone mixtures which have a considerably higher content of catalyst (100 ppm)are used for the coating of substrates, however. In systems with high catalyst
35 concentrations such as this, the aforementioned inhibitors do not fulfil the
requirements which are desired by the market as regards room temperature
.. . . ..... . . . . ..... ... .. .
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stability. US-A-4 851 452 ptoposes the use of Pt-vinylsiloxane complexes in
eombination with Pt-phosphine complexes as catalysts which haYe a signifieantly
decreased activity at room temperature. However, phosphines have the
disadvantage that the activity of the catalyst is also decreased to an appreciable
5 extent at elevated ~l..p~ld~Ulc~ (T=180C), i.e. under curing eonditions. For this
reason, they are only of very limited value for substrate coating applications.
a-hydroxyacetylenes, whieh are deseribed in detail in US-A-3 445 420, eonstitute -
another group of inhibitors which can be used. These e~mro~m~i~ do in fact
prolong the working life of the system "in bulk", but are extremely I '` y
10 as regards prolonging the working life of thin films such as those which are
present on the rollers during the coating operation.
The object of this invention is therefore to provide suitable mixtures which
decrease the aetivity of the catalyst at room Lclllpcld~UIc, even in rapid, addition-
~,lu~lillkillg silicone systems, without prolonging the curing times under reaction
15 conditions. At the same time, an object is to be able to prepare the mixture in a
simple manner and without safety risks.
It llas now been found that these problems can be solved with addition-erosslinking polysiloxane mixtures which contain Pt compounds or elemental Pt,
an a-hydlu~yacc~ylene or an ester of a dicarboxy acid and at least one
20 organophosphorus eompound of the type speeified in detail below.
The present invention therefore relates to ulu~ kal)le mixtures eûntaining
a) at least one polysiloxane which contains at least two olefinically or
acetylenically unsaturated multiple bonds,
b) at least ore polyll~.llu~;c..siloxane which eontains at least two hydrogen
atoms direetly bonded to silieon,
e) at least one substanee which eatalyzes hydrosilylation,
d) at least one inhibitor, and
e) at least one phosphorus eompound of formula (1)
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PR3 (1)
wherein
R each independently is H, Cl-CI8-alkyl, C6-C30-aryl, C7-C3l-
alkylaryl, or ORI
S Rl each in~ r~n~ is Cl-C18-alkyl, C6-C30-aryl, C7-C3l-alkylaryl,
and
wherein the aryl radicals may optionally be substituted with linear or branched
alkyl radicals and R and Rl may have a different meaning within the molecule,
and
f) optionally other auxiliary materials.
Component a) in the sense of the invention is preferably a cyclic, linear or
branched polysiloxane which is synthesized from units of tlle general formula (II)
(R3)a(R4)bsio(4 -a-b) 2 (Il)
Here, R3 represents a C2-C8 alkenyl radical, e.g. vinyl, allyl, I-butenyl, I-hexenyl,
etc. The alkenyl radicals may be bonded to silicon atoms within the chain or at
the end of the chain. R4 is a ~ luv 1~..., saturated lly~l~JuallJwl radical containing
up to 10 carbon atoms, from the group comprising substituted and .~
alkyl, aryl and arylalkyl radicals. Examples of monovalent radicals R4 include
methyl, ethyl, propyl, isopropyl, butyl, octyl, etc., cyclobutyl, cyclopentyl,
20 cyclohexyl, etc., phenyl, tolyl, xylyl, naphthyl, etc., and benzyl, phenylethyl or
phenylpropyl. The relationships 0 < a < 3, 0 < b < 3 and 0 < a + b < 4 apply
to the integers a and b. . a is preferably equal to 0 or 1. In radicals R4 of the
present invention, some or all of the hydrogen atoms may be substituted by
fluorine and / or chlorine, bromine, or iodine atoms or cyano radicals This means
25 that R4 may also be a chloromethyl, trinu~"o~",yl, chlorophenyl, dibromophenyl,
~3-cyanoethyl, ~-uya~ l or y-cyanopropyl radical, for example.
Using the nnm~n~l~fllre familiar to one skilled in the art:
,
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M: (CH3)3SiOI/2
D: (CH3)2SiO22
T: (CH3)SiO3/2
MVi: (cH2=cH)(cH3)2siol/2
5 DVi: (CH2=CEI)(CH3)siO2/2~
the following examples of component a) can be cited:
M2DIooD
M ViD
MViMDIooD
I O T5Ds5OM7Vi
T3DsooM2ViM3
T6D3OoDviM4vlM4 .
The molar proportion of unsaturated radicals of type R3 may be selected to have
any desired value.
In component a), the molar proportion of unsaturated radicals of type R3 should
preferably be between 0.01 and 10 mmole per gram, more preferably between 0.05
and I mmole per gram, and most preferably between 0.1 and 0.'.7 mmole per gram
of component a). The viscosity of component a) is preferably between 0.01 and
100,000 Pa s, more preferably between 10 and 100,000 mPa s at 25C.
Component b) in the sense of the present invention is a polysilo~ane which is
synthesized from units of general formula (III)
HC(R4)dsio(4 -c d)/2 (III)
where R4 has already been defined above and may optionally also have the
meaning of R3. The si~ ,hir~me~ric suffices c and d are integers, where 0 < d < 3
and 0 c c < 2, and where 0 < c + d < 4. Preferably, 0 < c < 1.
.
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Using the nomenclature familiar to one skilled in the art:
Mll: H(CH3)2SiOI,2
Dl~: H(CH3)SiO2/2,
the following examples of component b) can be cited:
M2 Dlo
MDIoDIoH
M211DZoDIoH
M viD H
M2D3ViD8H
(where M, D, MVi and DVi are defined as for component a)).
The molar proportion of hydrogen atoms which are directly bonded to a silicon
atom in component b) may be selected to have any desired value.
In component b), the molar proportion of hydrogen atoms which are directly
bonded to a silicon atom is preferably between 0.01 and 17 mmole, more
preferably between 0.1 and 1~ mmole, and most preferably between I and 17
mmole per gram of component b).
In the total mixture described above, r.nmrnnr-nt.i a) and b) should preferably be
present in a quantitative ratio such that the molar ratio of hydrogen atoms which
are directly bonded to silicon atoms (SiH) in component b) to the unsaturated
radicals (Si-vinyl) in corr;ponent a) is between 0 05 and 20, more preferably
between 0.5 and 10 and most preferably between 1 and 5.
Component c) in the sense of the invention preferably compnses the elements
platinum, rhodium, iridium, nickel, ruthenium and/or palladium, in elemental form
on a supporting substance or in the form of their compounds. Platinum
compounds or platinum complexes are preferred, such as H2PtCI6, platinum-olefin
complexes, platinum-alcohol complexes, platinum-vinylsiloxane complexes and
., . _, . .. , . .... ... ., ..... ..... .. . .. ... _ .. ......
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also elemental platinum on a supporting substance, such as activated carbon7
Al2O3 or SiO2 for exampie. Component c) is most preferably a platinum-vinyl-
siloxane complex. Platinum-vinylsiloxane complexes most preferably contain at
least two olefinically unsaturated double bonds in the siloxane; see US 3 715 334
5 for example.
The term "siloxane" includes polysiloxanes, i.e. it includes vi~ylpoly~;loxanes also,
for example. The proportion of component c) in the total mixture should -
preferably be between I and 1000 ppm, more preferably between I and 500 ppm,
and most preferably between 25 and 250 ppm.
10 Component d) in the sense of the invention comprises all the inhibitors which are
known in the prior art, such as maleic acid and derivatives thereof, amines, alkyl
isu~,y~lluldl~ and acetylenically unsaturated alcohols in which the OH group is
bonded to a carbon atom adjacent to the C-C triple bond, such as those describedin detail in US 3 445 420, for example. Component d) is preferably 2-methyl-3-
15 butyn-2-ol or l-ethynylcyclohexanol or (+) 3-phenyl-1-butyn-3-ol. Component d)
is preferably added to the mixture in a quantitative proportion of 0.0001 % to S %
with respect to the total weight of mixture, more preferably 0.01 % to 2 %, and
most preferably 0.1 to I %.
Component e) in the sense of the invention is an orgam",l~ ,llvlu~ compound of
20 type PR3. In this respect, R is a hydrogen atom or a monovalent hydrocarbon
radical from the group comprising Cl-C~s alkyl, C6-C30 aryl and C7-C3l alkylaryl.
R may have a different meaning within a molecule. In a preferred i-mhorlimPn~ ofthe present invention, component e) is a compound of formula P(ORI)3, where R~
= C~-CIs alkyl, C6-C30 aryl or C7-C3l alkylaryl, wherein the aryl radicals may
25 optionally be substituted with linear or branched alkyl radicals and Rl may have
different meanings within the molecule. Examples of component e) include
triphenylphosphine, triethylphosphine, tribu~ l.o~lli,.e, phosphoric acid trimethyl
ester, phosphoric acid triisopropyl ester, phosphoric acid triphenyl ester or tris-
(2,4-di-tert. butylphenyl)-phosphite. Component e) of the invention can also
30 include phosphite derivatives of pentaerythritol, such as, for example, bis (2,4-di-
tert.butylphenyl)-~ .yLl..i~ol diphosphite (obtainable from the &reak Dakes
Company under the trade name Alkanox P24(~). Component e) of the present
invention is preferably added in a quantitative proportion of 0.0001 % to S % with
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respect to the total weight of the mixture, more preferably 0.001 % to 4 % and
most preferably between 0.001 % and 2.~ %.
Examples of auxiliary materials (component f)) in the sense of the invention
include polysiloxane resins which are synthesized from Culllpu~ of general
formulae (II) and (111), filrers which have a positive effect on the mechanical and
electrical properties of the cured mixture according to the invention, such as
pyrogenic and ~ dte:l hydrated silicas having a BET specific surface of 5û to
50û m2/g, for example. The surfaces of fillers of this type may be modified, e g.
with organosilicon compounds. Modification may also be effected during tlleir
incorporation into the polymer, by the addition of hexamethyldisilazane or 1,3-
divinyl-1,1,3,3-tetramethyldisilazane with the addition of water, for example.
Substances such as ~ om~ oll~ earths, finely divided quartz flour, amorphous
hydrated silicas or carbon blacks may also be used as fillers, for example.
In another embodiment the mixtures according to the invention additionally
contain water or an orgMic solvent.
In a preferred embodiment of the invention, cul~ ullell~ a) and b) are present in a
quantitative ratio such that
the SiH:Si-vinyl ratio is between 0.1 and 10,
the content of component c) is between 1 and 1000 ppm,
the content of component d) is between 0.0001 and 5 %, and
the content of component e) is between 0.0001 and 5 %,
wherein the quantitative data are given with respect to the total weight of the
mixture in each case.
This invention also relates to a method of preparing the crosslinkable mixtures
according to the invention. In this process, ~ulllpu~ a), d) and e) are preferably
mixed, and thereafter component b) and finally component c) are added.
This invention further relates to the use of the crosslinkable mixture according to
the invention for the coating of substrates.
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The following examples serve to explain the invention. The invention is not
restricted to these examples, however.
Exam~les of ~
In the following examples, all parts by weight and p~ CS are given with
5 respect to the weight of the total mixture unless defined otherwise.
General (-~1" ' ' procedure for Examples la ~o lj
The quantitative data which do not appear in this description, as well as the type
of ~ and the experimental results, are given in Table 1.
9.15 g of a branched polydimethylsiloxane with a viscosity of ~ = 250 mPa s and
10 a content of vinyl groups bonded directly to silicon of 0.32 mmole/g were mixed
optionally with an cc-hyd~u~y~,c~ylene (see Table 1) and optionally with an
or~n-~rh--~rh~lrus compound (see Table 1) 0~5 g of a pulyllydl~ cilo~r~ne
having a content of hydrogen atoms bonded directly to silicon of 11~3 mmole/g
were then added ~inally, a sufficient amount of a soluhon of a Pt-vinylsiloxane
15 complex were added to the vinyl-containing polymer described above in order to
obtain a Pt content of 100 ppm. The meanings of the abbreviations in the
following Table are as follows:
ECH: I-ethynylcyclohexanol
PhB ~ 3-phenyl-1-butyn-3-ol
PoVI: triphenyl phosphite
PoVZ: triethyl phosphite
PoV3: triisopropyl phosphite
PoV4: tris-(2,4-di-tert butylphenyl)-phosphite
PoV5: triphenylphosphine oxide (companson)
PoV6: trimethyl phosphite
. ` ~e A 31 286-FQrei~n Cr~llntrjP~ 2 7 ~ ~ 4 ~ 1
Table
E~. a-hydrmcy- Amount Organo- Amount Workin~ Workin~
No. acctylcnc pho~phoru~ lifo a~ thin iirc in l~ulk
compouml film
lal) EC~ 27 mg - - 20 min 24 h
S Ibl) - - PoV4 10 mg 5 s 5 s
Ic ECI~ 27 mg PoV4 10 mg 22 h >10 days
Id ECH 27 mg PoV3 10 mg 3 h 15 min >6 days
le ECH 27 mg PoV2 10 mg 4 h 15 min >6 days
If ECH 27 mg PoV6 10 mg 2 h 20 min >6 days
10 Igl) - PoVI 10 mg 1 h 40 min >6 days
Ih ECH 27 mg PoVI 10 mg 22 h >10 days
lil) PhB 10 mg - - 20 min 24 h
Il rhB 10 mg PoVI 10 mg 26 h >10 days
~) comparative examples
15 The combination of 1.""l",.. ,l~ d) and e) is an essenùal part of this invention
As can be seen from ~WII~ala~;V~ examples la, Ib7 Ig and li, the presence of only
one of the two components does not result in a long working life.
Example 2
The following example demonstrates the effect of certain or~nr~rho~rhl~rus
20 compounds on the curing times at T = 180C. An o~-hydroxyacetylene and an
organu~ho~ .us compound, of the type and in the amounts given in detail in
Table 2, were added to 8 96 g of the vinyl-containing polymer described in
Example 1. Thereafter, 0.21 g of the polyhydrogensiloxane described in Example
I and a sufficient amount of the catalyst solution described in Example I were
25 added, in order to obtain a Pt content of 100 ppm. The results are given in Table
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Table 2
a-hydro~y- Amount Or~ano- Amount Working lifc Curing timc at
acotylcne pho~phoru~ a~ thin film T = 180C
compound
ECI~ 27 mg 20 min 7 s
S ECI~ 27 mg PoV4 10 mg 21 h 7 s
ECI~ 27 mg PoVS 10 mg 50 min >60 s
It will be understood that the specification and examples are illustrative but not
limitabve of the present invention and that other ~ budi~ b within the spirit
and scope of the invention will suggest themselves to those skilled in the art.
10 EYample 3
The following example is intended to demonstrate the synergistic effect of the
inhibitory activity of a dicarboxylic acid ester and an organophosphorus
compound.
9.15 g of a branched polydimethylsiloxane with a viscosity of ~ = 250 mPas and
15 a content of vinyl groups bonded directly to the silicon of 0.32 mmol g~l aremixed with an ul~lu~llo;,~)llul~ls compound and a dicarboxylic acid ester. Then
0.55 g of a polylly~lu~ siloxane which has a content of hydrogen atoms directly
bonded to the silicon of 11.3 mmol g~l is added. Then a sufficient quantity of asolution of a Pt/vinylsiloxane complex is added in order to obtain a Pt content of
20 100 ppm. The exact quantities and the type of inhibitors used are shown in Table
3. The organophosphorus compound has the name given in Example 1.
2 ~ 8~44 1
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T,tble 3
Ex. No. Dicarho~ylic Quantity Organo- Quantity Worldng life as acid cstcr ,oh~Jphorus thin rllm
compounll
3al dimethyl 0 mg PoV4 10 mg 5 sZ
maleate
3bl dimethyl 32 mg PoV4 O mg 25 min
maleate
5 3c dimethyl 32 mg PoV4 ~0 mg 12 h
maleate
I U~ Ja~ iV~ example
2The whole mixture gelated immediately after the introduction of the Pt catalyst solution
