Protective coatings
A mixture curable in the presence of a suitable metallic catalyst to provide an intumescent coating material. The mixture comprises: a siloxane polymer; a cross-linker for cross-linking the siloxane polymer; filler, wherein the filler comprises char reinforcing filler; and an intumescent ingredient. The intumescent ingredient comprises a phosphorus containing compound or a composition comprising a phosphorus containing compound. The mixture comprises 5 to 20% by weight of the phosphorus containing compound or composition comprising a phosphorus containing compound. The intumescent ingredient comprises 10 to 40% by weight expandable graphite.
1. A mixture curable in the presence of a suitable metallic catalyst to provide an intumescent coating material, wherein the mixture comprises:
a siloxane polymer;
a cross-linker for cross-linking the siloxane polymer;
filler, wherein the filler comprises char reinforcing filler; and
an intumescent ingredient, wherein the intumescent ingredient comprises expandable graphite and a phosphorus containing compound or a composition comprising a phosphorus containing compound, wherein the mixture comprises 5 to 20% by weight of the phosphorus containing compound or composition comprising a phosphorus containing compound;
wherein the expandable graphite is present in an amount between 10 to 40% by weight of the intumescent ingredient, and wherein the expandable graphite is a blend of two or more grades.
2. A mixture according to claim 1 , wherein the intumescent ingredient comprises 10 to 35% by weight expandable graphite.
3. A mixture according to claim 1 , wherein the phosphorus containing compound or composition comprising a phosphorus containing compound comprises ammonium polyphosphate.
4. A mixture according to claim 1 , wherein the mixture comprises 6 to 25% by weight of the char reinforcing filler.
5. A mixture according to claim 1 , wherein the mixture comprises 7 to 20% by weight of the char reinforcing filler.
6. A mixture according to claim 1 , wherein the expandable graphite has an onset of expansion temperature of 160 to 180° C.
7. A mixture according to claim 1 , wherein a first of the grades has a relatively low thermal expansion, and a second of the grades has a relatively high thermal expansion.
8. A mixture according to claim 1 , wherein the mixture comprises polydialkylsiloxane which is unreactive with the siloxane polymer.
9. A mixture according to claim 1 , wherein the siloxane polymer comprises polydiorganopolysiloxane.
10. A mixture according to claim 9 , wherein the polydiorganopolysiloxane comprises at least two condensable or hydrolyzable groups.
11. A mixture according to claim 10 , wherein the at least two condensable or hydrolyzable groups comprise hydroxyl groups or alkoxy groups.
12. A mixture according to claim 1 , wherein the suitable metallic catalyst comprises a metallic condensation catalyst.
13. A mixture according to claim 12 , wherein the metallic condensation catalyst comprises a tin based condensation catalyst.
14. A mixture according to claim 1 , wherein the filler comprises reinforcing and/or non-reinforcing filler.
15. A mixture according to claim 1 , wherein the mixture comprises an adhesion promotor.
16. A mixture according to claim 1 , wherein the mixture comprises a compatibilizer.
17. A method, the method comprising mixing:
a siloxane polymer;
a cross-linker for cross-linking the siloxane polymer;
filler, wherein the filler comprises char reinforcing filler; and
an intumescent ingredient, wherein the intumescent ingredient comprises expandable graphite and a phosphorus containing compound or a composition comprising a phosphorus containing compound, wherein the mixture comprises 5 to 20% by weight of the phosphorus containing compound or composition comprising a phosphorus containing compound; wherein the expandable graphite is present in an amount between 10 to 40% by weight of the intumescent ingredient, and wherein the expandable graphite is a blend of two or more grades;
the method further comprising allowing the mixture to cure in the presence of a suitable metallic catalyst to provide an intumescent coating material.
18. An intumescent coating material, wherein the intumescent coating material is the cured reaction product of a mixture comprising:
a siloxane polymer;
a cross-linker for cross-linking the siloxane polymer;
filler, wherein the filler comprises char reinforcing filler; and
an intumescent ingredient, wherein the intumescent ingredient comprises expandable graphite and a phosphorus containing compound or a composition comprising a phosphorus containing compound, wherein the mixture comprises 5 to 20% by weight of the phosphorus containing compound or composition comprising a phosphorus containing compound;
wherein the expandable graphite is present in an amount between 10 to 40% by weight of the intumescent ingredient, and wherein the expandable graphite is a blend of two or more grades.
19. A mixture according to claim 3 , wherein the mixture comprises 10 to 20% by weight of the ammonium polyphosphate.