Low modulus, humidity resistant silicone rtv compositions and method of preparing same
AssigneeHenkel Corporation
InventorAlfred A. DeCato
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Abstract
The present invention provides one-component silicone compositions, particularly useful as sealants, having low modulus and high elongation, as well as good resistance to high temperatures and humidity, and methods for preparing these sealants. In particular, the present invention provides compositions including a chain-extended curable polyorganosiloxane, a high molecular weight silicone gum and a cure system. The compositions may be used, for example, in sealing the stitching of automotive airbags.
Claims25
A composition comprising:
- a) a chain-extended curable polyorganosiloxane comprising the structure of formula III:
- wherein:
- R1 is selected from tert-butyl, alkyl, allyl, phenyl, alkenyl and aryl;
- R9, R10, R11 and R12 are independently selected from C1-4 alkyl;
- R13 is selected from alkoxy, acetoxy, enoxy, oximino and amino;
- R14 is selected from alkenyl and alkynyl;
- m is 10-2000;
- y is 1-50;
- z is 0-2;
- b) a high molecular weight silicone gum;
- and
- c) a cure system.
A composition comprising the reaction product of
- a) at least one hydroxy-functionalized polydiorganosiloxane;
- b) di (tert-butoxy) diacetoxysilane;
- c) vinyltrioximinosilane;
- d) a first adhesion promoter comprising tris(3-(trimethoxysilyl) propyl) isocyanurate;
- e) a second adhesion promoter comprising gamma-ureidopropyltrimethoxy wherein said first adhesion promoter is present in a ratio with said second adhesion promoter of about 3:1;
- and
- f) a catalyst.
A method of preparing a curable composition, comprising the steps of:
- a) reacting at least one hydroxy-functionalized polydimethylsiloxane with a silane comprising the structure:
- (R1O))x—Si—(R2)4-x
- wherein R1 is selected from tert-butyl, alkyl, allyl, phenyl, alkenyl and aryl, R2 is selected from alkoxy, alkenoxy, acetoxy, enoxy, oximo and alkyl and x is 1-2, in the presence of a catalyst;
- b) forming in situ a polyorganosiloxane comprising the structure of formula II:
- wherein R9, R10, R11 and R12 are independently selected from C1-4 alkyl, m is 10-2000 and y is 1-50;
- c) reacting formula II with a reactive silane selected from the group consisting of:
- alkoxy silanes;
- acetoxy silanes;
- enoxy silanes;
- oximino silanes;
- amino silanes;
- and combinations thereof;
- d) forming in situ a chain-extended curable polyorganosiloxane comprising the structure of formula III:
- wherein R13 is selected from alkoxy, acetoxy, enoxy, oximino and amino, R14 is selected from alkenyl and alkynyl and z is 0-2;
- and
- e) adding a high molecular weight silicone gum and a cure system to form a curable composition.
A method of sealing the stitching of an automobile airbag, comprising the steps of:
- a) providing a composition comprising:
- i) a chain-extended curable polyorganosiloxane comprising the structure of formula III:
- wherein:
- R1 is selected from tert-butyl, alkyl, allyl, phenyl, alkenyl and aryl;
- R9, R10, R11 and R12 are independently selected from C1-4 alkyl;
- R13 is selected from alkoxy, acetoxy, enoxy, oximino and amino;
- R14 is selected from alkenyl and alkynyl;
- m is 10-2000;
- y is 1-50;
- z is 0-2;
- ii) a high molecular weight silicone gum;
- and
- iii) a cure system;
- b) applying the composition to an inflatable substrate of an automobile airbag;
- c) exposing the substrate to moisture at ambient conditions;
- and
- d) stitching the substrate to form a sealed automobile airbag.
A composition comprising the reaction product of:
- a) a curable composition comprising:
- i) a chain-extended curable polyorganosiloxane comprising the structure of formula III:
- wherein:
- R1 is selected from tert-butyl, alkyl, allyl, phenyl, alkenyl and aryl;
- R9, R10, R11 and R12 are independently selected from C1-4 alkyl;
- R13 is selected from alkoxy, acetoxy, enoxy, oximino and amino;
- R14 is selected from alkenyl and alkynyl;
- m is 10-2000;
- y is 1-50;
- z is 0-2;
- and
- ii) a high molecular weight silicone gum;
- b) water;
- and
- c) a moisture curing catalyst.
Dependencies are inferred from the claim text.