Claims
- 1. A one-component RTV silicone rubber composition with good bonding properties even at high humidity conditions comprising (A) 100 parts by weight of a silanol end-stopped diorganopolysiloxane polymer having a viscosity of from 100 to 1,000,000 centipoise at 25.degree. C. where organo is a monovalent hydrocarbon radical (B) from 0.1 to 10 parts by weight of an acyloxy cross-linking agent of the formula,
- R.sub.m Si(OR.sup.1).sub.4-m
- where R is a monovalent hydrocarbon radical of 1 to 8 carbon atoms and R.sup.1 is an acyl radical of 2 to 20 carbon atoms, m is 0 or 1; (C) from 0.01 to 10 parts by weight of a curing promoter which is a metal salt of a carboxylic acid; and (D) about 4 parts by weight of acid scavenger selected from the group consisting of a magnesium or zinc salt of a carboxylic acid.
- 2. The composition of claim 1 wherein the acid scavenger is selected from the group consisting of zinc stearate, and magnesium stearate.
- 3. The composition of claim 2 wherein the cross-linking agent is methyl triacetoxysilane.
- 4. The composition of claim 2 wherein the cross-linking agent is methyl, tris (2-ethylhexanoxy) silane.
- 5. The composition of claim 4 wherein the curing promoter is dibutyl tin oxide.
- 6. The composition of claim 4 wherein the curing promoter is dimethyl tin bis-neodecanoate.
- 7. The composition of claim 6 further including from 1 to 10 parts by weight of an iron oxide thermal stabilizer.
- 8. The composition of claim 7 further comprising having therein from 10 to 100 parts by weight of a filler.
- 9. The composition of claim 8 wherein the filler is present at 10 to 100 parts by weight and is selected from the group consisting of fumed silica and precipitated silica.
- 10. The composition of claim 9 wherein the filler is treated with cyclopolysiloxanes prior to being incorporated into the composition.
- 11. The composition of claim 10 wherein the filler is treated with silazanes prior to being incorporated in the composition.
- 12. The composition of claim 10 wherein there is further present from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunctionality, tetra functionality or a mixture of tri and tetra functionality comprising
- (i) from 25 to 60 mole percent of monoalkylsiloxy units; siloxy units or a mixture of such units;
- (ii) from 1 to 6 mole percent of trialkylsiloxy units;
- (iii)from 34 to 74 mole percent of dialkylsiloxy units said polysiloxane containing from about 0.1 to 2% by weight of a silicone bonded hydroxyl groups.
- 13. The composition of claim 12 further including a sag control agent which is from 0.03 to 2 parts by weight of a polyether selected from the group consisting of
- A--O--(C.sub.x H.sub.2x O).sub.n --B
- and
- (A--O--(C.sub.x H.sub.2x O).sub.n).sub.y (Q).sub.z
- wherein A and B represent radicals selected from the group consisting of hydrogen, alkyl radicals containing 1 to 12 carbon atoms, cycloalkyl radicals containing 5 to 7 carbons in the ring, mononuclear and binuclear aryl radicals and mononuclear aryl lower alkyl radicals wherein the alkyl groups attached to the aroxatic nucleus contain a total of no more than 5 carbon atoms; ##STR5## where R.sup.2 is alkyl containing from 1 to 11 carbon atoms, Q is a residue of a polyhydroic initiator radical containing at least two hydroxyl radicals selected from the group consisting of ethylene glycol, glycerol, trimethylolpropane, and the polyhydric alcohols having from 2 to 6 hydroxyl groups, a is a number having a value of from 4 to 2000; x is a number having a value of 2 to 4; y has a value of from 2 to 10 and z has a value of from 1 to 5; the polyether having a moleculer weight of from about 300 to about 200,000.
- 14. The composition of claim 13 further including from 0.1 to 3 parts by weight of a self-bonding agent.
- 15. The composition of claim 14 wherein the self-bonding agent is 1, 3, 5-tristrimethoxysilylpropyl isocyanurate.
- 16. The composition of claim 14 wherein the self-bonding additive is selected from the group consisting of silyl maleates, silyl fumarates, silyl succinates and mixtures thereof.
- 17. The composition of claim 16 wherein the self-bonding additive is bis-trimethoxypropyl fumarate.
- 18. The composition of claim 16 wherein the self-bonding additive is bis-trimethoxypropyl maleate.
- 19. The composition of claim 16 wherein the silanol end-stopped diorganopolysiloxane polymer has the formula, ##STR6## where R.sup.3 and R.sup.4 are independently selected from monovalent hydrocarbon radicals and the value of s is such that the viscosity of the polymer varies from 100 to 1,000,000 centipoise at 25.degree. C.
Parent Case Info
This application is a division of application Ser. No. 571,138, now U.S. Pat. No. 4,680,363, filed 1/13/84 which is a continuation of 363,629 filed 03/30/82, now abandoned.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4680363 |
Beers |
Jul 1987 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
571138 |
Jan 1984 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
363629 |
Mar 1982 |
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