Polymeric organosilicon compounds, their production and use

Details Polymeric organosilicon compounds, their production and use Polymeric organosilicon compounds, their production and use

1999-08-13

2001-07-10

Moore, Margaret G. (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From silicon reactant having at least one...

C528S031000, C528S032000, C528S025000, C428S447000, C427S387000, C427S434300, C427S435000, C427S430100, C427S453000, C427S462000, C427S479000

Reexamination Certificate

active

06258913

ABSTRACT:

The invention relates to polymeric organosilicon compounds which contain hydrocarbon radicals having terminal aliphatic carbon-carbon double bonds, to a process for their preparation, and to their use in crosslinkable compositions, in particular for preparing antiadhesive coatings.
Polyaddition reactions of organopolysiloxanes having at least three Si-bonded hydrogen atoms per molecule with &agr;,&ohgr;-dialkenyldiorganopolysiloxanes lead, with a C═C/Si—H ratio of close to 1, to insoluble networks. If soluble alkenyl-containing organopolysiloxanes are to be prepared, a larger excess of the &agr;,&ohgr;-dialkenyldiorganopolysiloxane is necessary, which after the end of the polyaddition cannot be removed and thus dilutes the polyaddition product.
U.S. Pat. No. 5,241,034 discloses alkenyl-containing siloxane copolymers which are prepared by reacting an organic compound (1) having two, three or four terminal aliphatic carbon-carbon double bonds with an organopolysiloxane (2) which contains Si-bonded hydrogen atoms in the presence of a hydrosilylation catalyst. In this reaction, polyaddition products are obtained in which organopolysiloxane blocks are connected by hydrocarbon bridges. In order to obtain unsaturated siloxane copolymers the ratio of C═C double bond in organic compound (1) to Si-bonded hydrogen in the organopolysiloxane (2) must always be greater than 1. The organopolysiloxane (2) containing Si-bonded hydrogen atoms does not contain any alkenyl radicals.
U.S. Pat. No. 5,504,175 describes a process for preparing linear &agr;,&ohgr;-dialkenyldiorganopolysiloxanes in which a linear &agr;-hydrido-&ohgr;-alkenyldiorganopolysiloxane is reacted with a linear &agr;,&ohgr;-dialkenyldiorganosiloxane in the presence of a hydrosilylation catalyst. The linear &agr;,&ohgr;-dialkenyldiorganopolysiloxanes prepared by the process can contain on average not more than two alkenyl groups.
In J. Inorg. Organomet. Polymer 4 (1), 61 (1994) a process is described for preparing highly branched vinylsiloxanes. A platinum catalyst is added to tris(dimethylvinylsiloxy)silane, and the system reacts in an uncontrollable polyaddition to give siloxanes with a high vinyl density. Tris(dimethylvinylsiloxy)silane contains three vinyl groups and one Si-bonded hydrogen atom per molecule. Compounds which contain alkenyl groups and are free from Si-bonded hydrogen are not employed in the process.
The object was to provide polymeric organosilicon compounds which are branched or star-shaped, which contain on average more than two hydrocarbon radicals having at least one terminal aliphatic carbon-carbon double bond, which contain only small amounts of linear &agr;,&ohgr;-dialkenyldiorganopolysiloxanes, which can be prepared by a simple process, and which crosslink with organosilicon compounds containing Si-bonded hydrogen atoms in the presence of catalysts which promote the addition of Si-bonded hydrogen onto aliphatic multiple bond. The object was, furthermore, to provide crosslinkable compositions which are suitable for preparing coatings which repel tacky substances. The object is achieved by the invention.
The invention provides polymeric organosilicon compounds which contain hydrocarbon radicals having at least one terminal aliphatic carbon-carbon double bond, preparable by reacting
(A) compounds which contain at least one terminal aliphatic carbon-carbon double bond per molecule with
(B) oligomeric or polymeric organosilicon compounds which comprise units of the general formula
R
1
R
2
SiO
1/2
and units of the general formula
HRSiO and/or HSiO
3/2
and, if desired, units of the general formula
R
2
SiO,
where R is identical or different at each occurrence and is a monovalent, substituted or unsubstituted hydrocarbon radical having 1 to 18 carbon atoms per radical, which is free from aliphatic carbon-carbon double bonds,
R
1
is identical or different at each occurrence and is a monovalent hydrocarbon radical having 1 to 18 carbon atoms per radical, which contains at least one terminal aliphatic carbon-carbon double bond,
with the proviso that the sum of the units HRSiO and R
1
R
2
SiO
1/2
is on average greater than 2.0 if (B) contains no units HSiO
3/2
, and the number of radicals R
1
is on average greater than the number of Si-bonded hydrogen atoms, in the presence of
(C) catalysts which promote the addition of Si-bonded hydrogen onto aliphatic double bond,
the ratio of aliphatic double bond in components (A) and (B) to Si-bonded hydrogen in component (B) that is employed being from 1.5 to 10, preferably from 1.5 to 5.0, more preferably from 1.5 to 4.0,
with the proviso that the polymeric organosilicon compounds contain on average more than two hydrocarbon radicals having at least one terminal aliphatic carbon-carbon double bond.
The invention also provides a process for preparing polymeric organosilicon compounds which contain hydrocarbon radicals having at least one terminal aliphatic carbon-carbon double bond, which comprises reacting
(A) compounds which contain at least one terminal aliphatic carbon-carbon double bond per molecule with
(B) oligomeric or polymeric organosilicon compounds which comprise units of the general formula
 R
1
R
2
SiO
1/2
and units of the general formula
HRSiO and/or HSiO
3/2
and, if desired, units of the general formula R
2
SiO,
where R and R
1
are as defined above, with the proviso that the sum of the units HRSiO and R
1
R
2
SiO
1/2
is on average greater than 2.0 if (B) contains no units HSiO
3/2
, and the number of radicals R
1
is on average greater than the number of Si-bonded hydrogen atoms, in the presence of
(C) catalysts which promote the addition of Si-bonded hydrogen onto aliphatic double bond,
the ratio of aliphatic double bond in components (A) and (B) to Si-bonded hydrogen in component (B) that is employed being from 1.5 to 10, preferably from 1.5 to 5.0, more preferably from 1.5 to 4.0,
with the proviso that the resulting polymeric organosilicon compounds contain on average more than two hydrocarbon radicals having at least one terminal aliphatic carbon-carbon double bond.
The polymeric organosilicon compounds of the invention preferably have a viscosity of from 20 to 2,000,000 mPa.s at 25° C., preferably from 100 to 500,000 mPa.s at 25° C.
Preferably, the numerical content of hydrocarbon radicals having at least one terminal aliphatic carbon-carbon double bond in the polymeric organosilicon compounds of the invention is such that they contain on average from 2.5 to 50 terminal aliphatic carbon-carbon double bonds.
The polymeric organosilicon compounds of the invention preferably have iodine numbers of from 0.5 to 40, preferably from 1.0 to 20, the iodine number indicating the amount of iodine, in grams, consumed in the course of addition onto the double bond, per 100 grams of organopolysiloxane of the invention that is employed.
In the process of the invention it is preferred to employ as component (A) polymeric organosilicon compounds selected from the group of the general formula
R
1
a
R
3−a
Si(R
1
RSi)
n
(R
2
Si)
m
SiR
1
a
R
3−a
  (I)
R
1
a
R
3−a
SiO(R
1
RSiO)
n
(R
2
SiO)
m
SiR
1
a
R
3−a
  (II)
and
R
1
a
R
3−a
Si—R
2
—(R
1
RSi—R
2
—)
n
(R
2
Si—R
2
—)
m
SiR
1
a
R
3−a
  (III),
preferably organopolysiloxanes of the general formula
R
1
a
R
3−a
SiO(R
1
RSiO)
n
(R
2
SiO)
m
SiR
1
a
R
3−a
  (II)
where R and R
1
are as defined above,
R
2
is a divalent hydrocarbon radical having 2 to 8 carbon atoms,
a is identical or different at each occurrence and is 0 or 1, preferably 1,
n is 0, 1, 2, 3 or 4, preferably 0, 1 or 2, and
m is 0 or an integer from 1 to 1500,
with the proviso that they contain at least one terminal radical R
1
per molecule.
The organosilicon compounds of the formula (I), (II) or (III) which are employed as component (A) can also comprise, to a minor extent, preferably less than 5 mol-%, T or Q units, and also bifunctional bridges or trifunctional organic branching sites.
The organopolysiloxanes of the formula (II) preferably have a viscosity o

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