Crosslinkable organopolysiloxane compositions

Details Crosslinkable organopolysiloxane compositions Crosslinkable organopolysiloxane compositions

2000-11-17

2002-11-26

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...

C528S034000

Reexamination Certificate

active

06486288

ABSTRACT:

TECHNICAL FIELD
The invention relates to organopolysiloxane compositions which are stable on storage in the absence of moisture and can be crosslinked at room temperature on admission of moisture using a titanium catalyst, and to a process for preparing such compositions.
BACKGROUND ART
The use of titanium(IV) compounds, particularly chelated titanates, as condensation catalysts in RTV-1 silicone rubbers is generally known. In RTV-1 compositions, these titanium compounds have the disadvantage that they cause undesirable yellowing of the rubbers and thus make it possible to obtain only pigmented compositions, but no translucent compositions. Numerous methods have therefore been developed for reducing yellowing, for instance additives which suppress yellowing as disclosed in U.S. Pat. No. 4,906,719; the use of phosphatotitanates in RTV isocyanate systems as described in U.S. Pat. No. 4,433,127; the use of specific titanium catalysts which are prepared by reaction of organotitanates with hydroxycarboxylic esters, as known from DE 42 13 873; specific titanium catalysts which are prepared by reaction of organotitanates with a &bgr;-dicarbonyl compound and additionally with a citric ester, as disclosed in U.S. Pat. No. 5,428,103; and specific titanates whose organic radicals are derived from monohydric alcohols and diols or dihydroxycarboxylic acids, as described in DE 44 27 528 A.
DISCLOSURE OF INVENTION
The present invention is directed to storage stable, moisture curable compositions employing hydrolyzable organosilicon compounds, and employing as a condensation catalyst, at least one titanium compound of the formula
 Ti(OR)
4-n
[(OR
1
)
x
—OR
2
]
n
  (I)
where
R may be identical or different and are monovalent, substituted or unsubstituted hydrocarbon radicals,
R
1
may be identical or different and are divalent, substituted or unsubstituted hydrocarbon radicals,
R
2
may be identical or different and are as defined for R,
n is 1, 2, 3 or 4 and
x is an integer greater than or equal to 1.
BEST MODE FOR CARRYING OUT THE INVENTION
The invention provides organopolysiloxane compositions which are stable on storage in the absence of moisture and can be crosslinked at room temperature on admission of moisture, these compositions comprising organosilicon compounds containing at least two hydrolyzable groups, and comprising, as a catalyst, at least one titanium compound of the formula
Ti(OR)
4-n
[(OR
1
)
x
—OR
2
]
n
  (I)
wherein
R may be identical or different and are monovalent, substituted or unsubstituted hydrocarbon radicals,
R
1
may be identical or different and are divalent, substituted or unsubstituted hydrocarbon radicals,
R
2
may be identical or different and are as defined for R,
n is 1, 2, 3 or 4 and
x is an integer greater than or equal to 1.
The compositions of the invention are preferably one-component compositions which vulcanize at room temperature (RTV-1 compositions). Depending on the application, these can be solid or fluid.
Examples of radicals R are alkyl radicals such as the methyl, ethyl, n-propyl, isopropyl, 1-n-butyl, 2-n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl or tert-pentyl radicals; hexyl radicals such as the n-hexyl radical; heptyl radicals such as the n-heptyl radical; octyl radicals such as the n-octyl radical and isooctyl radicals such as the 2,2,4-trimethylpentyl radical; nonyl radicals such as the n-nonyl radical; decyl radicals such as the n-decyl radical; dodecyl radicals such as the n-dodecyl radical; octadecyl radicals such as the n-octadecyl radical; cycloalkyl radicals such as the cyclopentyl, cyclohexyl or cycloheptyl radicals and methylcyclohexyl radical; alkenyl radicals such as the vinyl, 1-propenyl and 2-propenyl radicals; aryl radicals such as the phenyl, naphthyl, anthryl and phenanthryl radicals; alkaryl radicals such as o-, m-, p-tolyl radicals, xylyl radicals and ethylphenyl radicals; and aralkyl radicals such as the benzyl radical, the &agr;-phenylethyl radical and the &bgr;-phenylethyl radical.
Examples of substituted radicals R are haloalkyl radicals such as the 3,3,3-trifluoro-n-propyl radical, the 2,2,2,2′,2′,2′-hexafluoroisopropyl radical and the heptafluoroisopropyl radical, and haloaryl radicals such as the o-, m- and p-chlorophenyl radicals.
The radicals R are preferably unsubstituted or halogen-substituted, monovalent hydrocarbon radicals having from 1 to 18 carbon atoms, most preferably alkyl radicals, in particular the ethyl radical and the isopropyl radical.
Examples of radicals R
1
are alkylene radicals such as the methylene, ethylene, propylene, methylethylene and butylene radicals. The radicals R
1
are preferably unsubstituted or halogen-substituted, divalent hydrocarbon radicals having from 1 to 4 carbon atoms, particularly preferably the ethylene, methylethylene and butylene radicals, in particular the methylethylene radical and ethylene radical.
Examples of radicals R
2
are the examples given for R, with preference being given to alkyl radicals and particular preference being given to ethyl and methyl radicals.
In the above formula, n is preferably 2, 3 or 4, in particular 4, and x is preferably an integer from 2 to 12, more preferably from 2 to 4.
Examples of titanium compounds of the formula (I) used according to the invention are
Ti[(OCH
2
CH
2
)
2-12
—OCH
3
]
4
,
Ti[(OCH
2
CH
2
)
2-12
—O—CH
2
CH
2
CH
2
CH
3
]
4
,
Ti[(OCH(CH
3
)CH
2
)
2-12
—OCH
3
]
4
,
Ti[(OCH(CH
3
)CH
2
))
2-12
—O—CH
2
CH
2
CH
2
CH
3
]
4
,
Ti(OEt)
2
[(OCH
2
CH
2
)
2-12
—OCH
3
]
2
and
Ti(OiPr)[(OCH
2
CH
2
)
2-12
—OCH
3
]
3
, where Et is ethyl and iPr is isopropyl, with preference being given to Ti[(OCH
2
CH
2
)
2-12
—OCH
3
]
4
and particular preference being given to Ti[(OCH
2
CH
2
)
2-4
—OCH
3
]
4
.
The titanium compounds of the formula (I) used according to the invention are commercial products or can be prepared by chemical methods known per se, for instance by reaction of Ti(OR)
4
with n H[(OR
1
)
x
OR
2
] with elimination of n HOR, where R, R
1
, R
2
, n and x are each as defined above. Both Ti(OR)
4
and H[(OR
1
)
x
OR
2
] are commercial products or can be prepared by known chemical methods.
The catalysts used according to the invention can also be prepared in situ by direct addition of the starting materials, e.g. oligomeric polyxyalkylated alcohols and tetraorganotitananates Ti(OR)
4
, to the crosslinkable organopolysiloxane compositions.
In addition to the titanium compounds used according to the invention as condensation catalysts, the compositions of the invention may further comprise all components which have been used hitherto for preparing organopolysiloxane compositions which are stable on storage in the absence of moisture and can be crosslinked at room temperature on admission of moisture. The hydrolyzable groups present in the organosilicon compounds which participate in the crosslinking reaction can be any hydrolyzable groups, for example organyloxy groups, in particular alkoxy radicals such as ethoxy radicals, alkoxyethoxy radicals and methoxy radicals. The organosilicon compounds can have siloxane (≡Si—O—Si≡) structures or silocarbane (≡Si—R
5
—Si≡ structures where R
5
is a divalent, substituted or unsubstituted hydrocarbon radical), or their copolymers, for instance organosilicon compounds of the formula (R
3
O)
3-a
R
4
a
Si—R—[R
4
2
SiO]
b
—R
4
2
Si—R
5
—SiR
4
a
(OR
3
)
3-a
, where R
3
, R
4
, a and b are as defined for formula (II) below, and R
5
is a divalent, substituted or unsubstituted hydrocarbon radical. Reference may be made, for example, to EP 747 443 A2, page 2, lines 42 to 53.
The crosslinkable organopolysiloxane compositions of the invention are preferably ones which comprise
(A) essentially linear diorganopolysiloxanes having at least two organyloxy radicals at each end group,
(B) organyloxy-functional crosslinkers having at least three organyloxy groups and/or their partial hydrolyzates an

Affiliated with

Also associated with

Rating

Crosslinkable organopolysiloxane compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Crosslinkable organopolysiloxane compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crosslinkable organopolysiloxane compositions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2950040