Crosslinkable organopolysiloxane materials

Details Crosslinkable organopolysiloxane materials Crosslinkable organopolysiloxane materials

1998-12-23

2002-02-19

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...

C528S015000, C528S031000, C528S032000, C524S730000, C524S731000

Reexamination Certificate

active

06348557

ABSTRACT:

The invention relates to crosslinkable organopolysiloxane compositions which are prepared with addition of low molecular weight organosilicon compounds.
For the purposes of the present invention, the term organopolysiloxanes encompasses dimeric, oligomeric and polymeric siloxanes.
DE-B 24 22 846 (Rhone-Poulenc S.A.; issued on Apr. 23, 1976) and the corresponding U.S. Pat. No. 3,933,729 and U.S. Pat. No. 3,983,265 describe condensation-crosslinkable organopolysiloxane compositions which, to improve adhesion, contain from 10 to 50 parts of MQ resin having a ratio of triorganosiloxy units (M units) to SiO
4/2
units (Q units) of less than or equal to 1.2.
EP-A 217 333 (Dow Corning Corp.; issued on Oct. 18, 1989) discloses a process for preparing condensation-crosslinking RTV-1 compositions based on hydroxyl-terminated poly(trifluoropropyl)methylsiloxane, silica and 1,3-bis(3,3,3-trifluoropropyl)tetramethyldisilazane.
DE-A-42 16 139 (Wacker-Chemie GmbH; issued on Nov. 18, 1993) and the corresponding US application having the serial number U.S. Ser. No. 08/313,192 describes MQ resins having a ratio of M units to Q units of less than or equal to 1. Powders having a particle size of, for example, 1-100 &mgr;m can be prepared from these resins. The molecular weight is, in particular, from 500 to 10,000 g/mol.
The German application number 195 45 363.8 (Wacker-Chemie GmbH; filed on Dec. 5, 1995) describes the use of low molecular weight organosilicon compounds containing aliphatically unsaturated radicals in crosslinkable compositions based on organopolysiloxanes.
WO 93/17654 describes addition-crosslinking dental compositions and the addition of resins comprising M and Q constituents and having a molecular weight of 100-100,000. EP-A-0 291 871 describes the preparation of H-siloxanes having 3-5 Si atoms and their use as building blocks in chemical synthesis (hydrosilylation) and in organopolysiloxanes as coupling agent. DE-A-26 09 681 describes the preparation of low molecular weight SiOH-siloxanes and their later use, with the silanol content of the low molecular weight siloxanes being 6.5<OH<14% by weight. JP-A-01203467 describes the use of siloxanes comprising D units as additives in peroxidically crosslinking HTV rubber. DE-A-41 14 554 describes the preparation of H-siloxanes having 3-1000 Si atoms and their use as coupling agents in silicone rubber. EP-A-0 693 533 and EP-A-0 575 863 each describe condensation-crosslinking compositions. U.S. Pat. No. 3,361,714 describes peroxidically crosslinking HTV compositions and the use of compounds of the type M
a
D
b
T
c
. EP-A-0 651 021 describes addition-crosslinking compositions and the use of MQ resin with M:Q of from 1:1 to 2:1 and comprising M and Q units; according to page 4, lines 51-55 small amounts of low molecular weight MQ resins can be present as a result of the method of preparation. EP-A-0 628 617 describes high temperature condensation-crosslinking compositions and describes the use of solid MQ compounds with M:Q of from 0.5:1 to 1.2:1 and comprising M and Q units.
The invention provides crosslinkable, organopolysiloxane-based compositions which comprise, in addition to organopolysiloxanes, at least one low molecular weight organosilicon compound having from 2 to 17 silicon atoms and comprising units of the formula
R
1
a
R
2
b
(OR
3
)
c
SiO
4−(a+b+c)/2
  (I)
where
R
1
can be identical or different and are each a hydrogen atom or an aliphatically saturated, SiC-bonded hydrocarbon radical having from 1 to 18 carbon atoms, where at most one radical R
1
per silicon atom can be a hydrogen atom,
R
2
can be identical or different and are each an aliphatically saturated, halogen-substituted SiC-bonded hydrocarbon radical having from 1 to 18 carbon atoms,
R
3
can be identical or different and are each a hydrogen atom or an unsubstituted or halogen-substituted hydrocarbon radical having from 1 to 12 carbon atoms, which may be interrupted by oxygen atoms,
a is 0, 1, 2 or 3,
b is 0, 1, 2 or 3,
c is 0, 1, 2 or 3 and
the sum of a, b and c in formula (I) is less than or equal to 3, with the proviso that low molecular weight organosilicon compounds comprising units of the formula (I) where b=0 contain at least one unit of the formula (I) in which a is 0 or 1 and at least one unit of the formula (I) in which a is 3.
The low molecular weight organosilicon compounds used according to the invention have a molecular weight of preferably from 150 to 2500 g/mol, particularly preferably from 150 to 1500 g/mol, in particular from 150 to 500 g/mol.
The low molecular weight organosilicon compounds used according to the invention preferably have a boiling point of greater than 200° C. at a pressure of from 900 to 1100 hPa.
Examples of aliphatically saturated hydrocarbon radicals R
1
are alkyl radicals such as the methyl radical, the ethyl radical, propyl radicals such as the iso- or n-propyl radical, butyl radicals such as the tert- or n-butyl radical, pentyl radicals such as neo-, iso- or n-pentyl radicals, hexyl radicals such as the n-hexyl radical, heptyl radicals such as the n-heptyl radical, octyl radicals such as the 2-ethylhexyl or n-octyl radical, decyl radicals such as the n-decyl radical, dodecyl radicals such as the n-dodecyl radical, hexadecyl radicals such as the n-hexadecyl radical and octadecyl radicals such as the n-octadecyl radical, aryl radicals such as the phenyl, biphenyl or naphthenyl radical, alkylaryl radicals such as benzyl, ethylphenyl, toluyl or xylyl radicals.
The radical R
1
is preferably an aliphatically saturated hydrocarbon radical having from 1 to 18 carbon atoms, particularly preferably a methyl radical, phenyl radical or octyl radical, in particular the methyl radical for reasons of availability.
Examples of radical R
2
are halogenated aliphatically saturated alkyl radicals such as the 3-chloropropyl, 3,3,3-trifluoro-n-propyl, 2,2,2,2′,2′,2′-hexafluoroisopropyl, heptafluoroisopropyl or perfluorohexylethyl radical, halogenated aryl radicals such as the o-, m-, p-chlorophenyl or o-, m-, p-chlorobenzyl radicals.
The radical R
2
is preferably a 3,3,3-trifluoropropyl radical or a perfluorohexylethyl radical, with particular preference being given to the 3,3,3-trifluoropropyl radical for reasons of availability.
Examples of hydrocarbon radicals R
3
are the radicals having from 1 to 12 carbon atoms indicated for R
1
and R
2
and also alkoxyalkyl radicals such as the methoxymethyl radical and the ethoxyethyl radical and alkenyl radicals such as the vinyl and allyl radicals.
The radical R
3
is preferably a hydrogen atom or a methyl or ethyl radical, with particular preference being given to a hydrogen atom.
The organosilicon compounds used according to the invention can be branched, linear or cyclic siloxanes, with the proviso that low molecular weight organosilicon compounds comprising units of the formula (I) where b=0 contain at least one unit of the formula (I) in which a is 0 or 1 and at least one unit of the formula (I) in which a is 3.
The low molecular weight organosilicon compounds used according to the invention are preferably compounds which consist of M units, i.e. units of the formula (I) where a+b=3, and also Q units, i.e. units of the formula (I) where a+b=0, and/or T units, i.e. units of the formula (I) where a+b=1, where the numerical ratio of M units to the sum of Q units and/or T units is greater than or equal to 1, preferably greater than or equal to 2, particularly preferably greater than or equal to 2.5, or compounds which consist of units of the formula (I) where a=b=1 and, if desired, units of the formula (I) where a=b=c=1.
The low molecular weight organosilicon compounds used according to the invention are particularly preferably compounds which consist of M units, i.e. units of the formula (I) where a+b=3, and Q units, i.e. units of the formula (I) where a+b=0, where the numerical ratio of M units to Q units is greater than or equal

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