Title of Invention

A ROOM TEMPERATURE CURABLE FLAME RETARDANT COMPOSITION

Abstract ABSTRACT A room temperature curable flame retardant composition comprises a linear organo polysiloxane, a silane compound, a metallic salt of a carboxylic acid, an inorganic filler such as silicon carbide, an organo phosphate and traces of platinum or platinum containing complex. This invention also includes a curable polysiloxane containing composition which contains polysiloxane and an inorganic filler such silicon carbide, an organo phosphate and traces of platinum or platinum containing complex. A composition for curing the above composition containing an alkyl oximo silane, aminoalkyl tri alkoxy silane and a metallic salt of a carboxylic acid.
Full Text

This invention relates to a room temperature curable flame retardant composition containing organo polysiloxane. The composition in the cured state exhibits excellent flame retardant properties when compared to the hitherto known flame retardant compositions.
Many commercially, industrially and domestically used materials are either combustible or inherently support combustion. Protection from fire and fire safety requirements are high in the agenda of both consumers and manufacturers. Various fire retardant compositions have been developed to reduce or to overcome the combustible nature of materials. Broad spectrum fire inhibitors known in the art are highly halogenated and give out highly toxic vapours when burnt
Self extinguishable and room temperature curable fire retardant composition according to the invention are useful as fire proof coatings on electrical insulation, for encapsulating electrical equipments and as sealants. They may be stored and shipped in the uncured state and avoids gelling on storage. This composition does not emit highly toxic fumes when burnt Moreover, such coatings avoid formation of dense smoke in the event of fire.
The flame retardant composition according to this invention comprises (1) a linear polyorgano siloxane having terminal silicon bonded hydroxy groups and an average of two methyl groups per silicon atom, (2) a silane of the formula R-Si-Y3 wherein R is an alkyl radical and Y is a radical of the formula -0-N=CR'R" wherein each R' and R" are selected from methyl and ethyl radicals, (3) a metallic salt of an organic carboxylic acid, (4) an organic phosphate, (S) an inorganic filler and (6) platinum or platinum containing compound.

In a preferred embodiment the components have the following weight ratio based on the weight of polyorgano siloxane.
100 parts by weight of polyorgano siloxane having terminal silicon bonded hydroxy groups, 2 to 20 parts by weight of a silane of the formula R-Si-Y3 where R and Yj have the meaning as described herein above, 50 to 200 parts by weight of an inorganic filler, all weights based on 100 parts by weight of the polyorgano siloxane and 10 to 250 parts per million by the weight of platinum or a platinum compound based on the polyorgano siloxane. 0.5 to 2 parts of a metal dicarboxylic acid salt based on the weight of silane the formula R-Si-Y3 is also added to the composition.
The preferred polyorgano siloxane is linear methyl polysiloxane which is well known in the art and may be prepared by heating a mixture of cyclic dimethyl polysiloxane of the formula [(CH3)2 Si 0]„, wherein n is at least three, siloxane rearrangement catalysts and condensation catalysts such as potassium hydroxide, tetra butyl phosphonium hydroxide and tetra methyl ammonium hydroxide. The mixture may be heated to 120°C to 150°C and the product may be recovered in a known maimer.
Silanes of the formula R-Si-Y3 are also known in the art. Ketoxime silanes are described in US patent no.3,189,576 which is incorporated by way of reference.
Organo phosphates upto 20 parts by weight added to the composition improves the process ability of the premix and enhances its fire retardant qualities. Tricresyl phosphate is an example of the organo phosphate used in the coating.

Any known inorganic fillers may be added to the mixture, though it is noticed that silicon carbide powder when used as a filler imparts superior fire retardancy to the composition. Preferably silicon carbide having an average particle size of 5 to 20 microns may be used. Silicon carbide may be prepared by Acheson process in which a mixture of silica rock and carbon is heated and reacted at high temperature in an electric furnace.
Platinum is present in the composition in the range of 10 to 250 parts by weight per million parts by weight of the organo siloxane. Platinum in any form which permits homogeneous dispersion in the composition may be used. Readily dispersible platinum compounds and complexes are known in the art. They include chloroplatinic acid, platinum chlorides, platinum bromides, and complexes of platinum halides with an olefin such as ethylene, propylene. Styrene complex of platinum with cyclohexane may also be used. Any known platinum containing compound or complex which is used and known in the field of Si H - Si-olefin addition reaction may be effectively employed.
It is observed that addition of platinum in an amount more than 300 parts per million does not effectively improve the quality of the final product. It is also essential to thoroughly mix platinum with the other constituents of the composition. Conventional techniques like kneading and milling may be used for preparing a homogeneous composition. This composition may be prepared by mixing the components in anhydrous conditions. For thorough mixing of the components, a three roll mill may be used.
This invention also includes an organopoly&iloxane composition curable at room temperature which in the cured state exhibit enhanced fire retardancy.

This composition consists of an oraganopolysiloxane which contains terminal silicon bonded hydroxy groups and has an average of at least two methyl groups per silicon atom. A preferred siloxane is methyl polysiloxane. The other component of this curable composition is a silane of the formula R-S1-Y3 wherein R is an alkyl radical and Y is a radical of the formula -0-N=CR'R" in which each R' and R" are either methyl or ethyl. Addition of a curing agent to this composition triggers the production of the cured compound in the composition which is a silicon polymer free of silicon bonded hydrogen atom.
This invention also includes a curing agent for curing the above mentioned polysiloxane composition. The curing agent composition consists of an alkyl oximinosilane, aminoalkyl tri- alkoxysilane and a metallic salt of a carboxylic and preferably, this composition contains methyl trimethyl ethyl ketoxime silane, 3-aminopropyl triethoxy silane and dibutyl tin dilaurate. Preferred range of these compounds in the composition based on the alkyl oximino silane is 10 to 20% of aminoalkyl triaJkoxysilane and 0.5 to 2% of the organo tin compound, the balance being alkyl oximino silane. It is observed that about 2 to 5% by weight of this composition is sufficient to initiate and complete curing of the room temperature curable composition discussed herein before.
Accordingly, this invention provides a room temperature curable flame retardant composition which comprises (1) a linear polyorgano siloxane having terminal silicon bonded hydroxy groups and an average of two methyl groups per silicon atom, (2) a silane of the formula R-Si-Y3 wherein R is an alkyl radical and Y is a radical selected from the groups consisting of an acetoxy radical and a ketoxime radical of the formula -0-N=CR'R" wherein each R' and R" are selected from methyl and ethyl radicals, (3) a metallic salt of a carboxylic acid, (4) an organic phosphate, (5) an inorganic filler and (6) platinum or a platinum containing compound.

This invention nirther includes a composition for curing the said organo polysiloxane composition which comprises an aikyl oxunino silane, aminoalkyl tri-alkoxy silane and a metallic salt of a carboxylic acid.
Obvious equivalents known to persons skilled in the art are not excluded from the scope of the appended claims.


WE CLAIM;
1. A room temperature curable flame relardanl composition comprising (i) a linear polyorgano siloxane having terminal silicon bonded hydroxy groups and an average of two methyl groups per silicon atom, (ii) a silane of the formula R-S1-Y3 wherein R is an alkyl radical, and Y is a radical selected from the groups consisting of an ac-etoxy radical and a ketoxime radical of the formula -0-N=CR'R" wherein ea^h R' and R" are selected from methyl and ethyl radicals, (iii) a metallic salt of a carboxylic acid, (iv) an organo phosphate, (v) a known filler, and (vi) platinum or a platinum containing compound.
1 The composition as claimed in claim 1 which comprises 100 parts by weight of
said polyorgano siloxane, 2 to 20 parts by weight of said silane, containing 0.5
to 2 parts by weight of said metallic carboxylic acid salt, 50 to 200 parts by
weight of said inorganic filler, all weights based on 100 parts by weight of said
\ polyorgano siloxane and 10 to 250 parts by weight per million of said platinum
1 or platmum containing compound.
3. The composition as claimed in claims 1 or 2 wherein said polyorgano siloxane
is linear dimethyl polysiloxane.
4. The composition as claimed in any one of the claims 1 to 3 wherein said
i organo phosphate is trycresyl phosphate.
5. The composition as claitfjed in any one of the claims 1 to 4 wherein said
I inorganic filler is silicon carbide having an average particle size of 5 to 20
Wcrons.

6. The composition as chmncu in any one of the claims 1 to 5 wherein said platinum compound is readily dispersible and is selected from chloroplatinic acid, platinum halides and platinum containing organic complexes.
7. A cured product obtained by curing the composition as claimed in any one of the claims 1 to 6 at a temperature range of 20 to 40°C for 24 to 48 hours.
8. An organopolysiloxane composition curable at room temperature comprising an organo polysiloxane having terminal silicon bonded hydroxy groups and an average of at least two methyl groups per silicon atoms, and a silane of the formula R-Si-Y3 wherein R is an alkyl radical, and Y is a radical selected from the groups consisting of an acetoxy radical, and a ketoxime radical of the formula -0-N=CR'R" wherein each R' and R" are either methyl or ethyl.
9. The composition as claimed in claims 7 or 8 wherein said silane is present in an amount of 2 to 20 parts by weight based on 100 parts by weight of said organo polysiloxane.
10. A composition for curing the organo polysiloxane composition as claimed in claims 8 or 9 comprising an alkyl oximino silane, aminoalkyl tri alkoxysilane and a metallic salt of a carboxylic acid.
11. The composition as claimed in claim 10 wherein said oximino silane is methyl tris methyl ethyl ketoxime silaxane and aminoalkyl tri alkoxy silane is 3-amino propyl tri ethoxy silane and said metallic sah of carboxylic acid is dibutyl tin dilaurate.

12. An organo polysiloxane composition curable at room temperature substantially as herein described.
13- A composition for curing organo polysiloxane composition substantially as herein described.
14. A room temperature curable flame retardant composition substantially as herein described.


Documents:

0110-che-2003 abstract duplicate.pdf

0110-che-2003 abstract.pdf

0110-che-2003 claims duplicate.pdf

0110-che-2003 claims.pdf

0110-che-2003 correspondence-others.pdf

0110-che-2003 correspondence-po.pdf

0110-che-2003 description (complete) duplicate.pdf

0110-che-2003 description (complete).pdf

0110-che-2003 form-1.pdf

0110-che-2003 form-19.pdf

0110-che-2003 form-26.pdf

0110-che-2003 form-3.pdf


Patent Number 206764
Indian Patent Application Number 110/CHE/2003
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date 11-May-2007
Date of Filing 07-Feb-2003
Name of Patentee INDIAN SPACE RESEARCH ORGNAISATION
Applicant Address ISRO HEADQUATTERS, DEPARMENT OF SPACE, ANTARIKSH BHAVAN, NEW BEL ROAD, BANGALORE 560 094
Inventors:
# Inventor's Name Inventor's Address
1 GEETHA JANARDHANAN NAIR C/O VIKRAM SARABHAI SPACE CENTRE, THIRUVANANTHAPURAM-695 022.
PCT International Classification Number C08K3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA