Intumescent coating composition with enhanced metal adhesion
View Patent ↗An intumescent coating composition and a process for curing the coating to obtain an intumescent coating is provided. The intumescent coating composition contains a thermoplastic polymer which comprises as a copolymerized component, an acid (meth)acrylate or a copolymerizable polyfunctional carboxylic acid; at least one ethylenically unsaturated monomer; an azo or organic peroxide initiator; an acid source; a carbon source; and a gas source.
1. An intumescent coating composition, comprising:
a thermoplastic polymer which comprises as a copolymerized component, an acid (meth)acrylate or a copolymerizable polyfunctional carboxylic acid such that at least one acid carboxylate group is pendant to the carbon-carbon chain of the thermoplastic polymer;
at least one ethylenically unsaturated monomer;
an azo or organic peroxide initiator;
an acid source;
a carbon source; and
a gas source;
wherein the thermoplastic polymer is a (meth)acrylate polymer or a polymer of at least one vinyl monomer selected from the group consisting of styrene, vinyltoluene, vinyl chloride, vinyl acetate, vinylidene chloride and a vinyl ester, and
wherein the polymer of the vinyl monomer optionally comprises a diene component.
2. The intumescent coating composition according to claim 1 , wherein the copolymerized component of the thermoplastic polymer is a copolymerizable polyfunctional carboxylic acid which is a dicarboxylic acid.
3. The intumescent coating composition according to claim 1 , wherein the copolymerized component of the thermoplastic polymer is an acid (meth)acrylate which is a beta-carboxyethyl acrylate (beta-CEA) of formula:
4. The intumescent coating composition according to claim 1 , wherein the copolymerized component of the thermoplastic polymer is a copolymerizable polyfunctional carboxylic acid which is selected from the group consisting of itaconic acid, fumaric acid and maleic acid.
5. The intumescent coating composition according to claim 1 , wherein a content of the thermoplastic polymer, is from 10 to 60% by weight of the total weight of the intumescent coating composition.
6. The intumescent coating composition according to claim 1 , wherein the thermoplastic polymer comprises a (meth)acrylate as a polymerized component.
7. The intumescent coating composition according to claim 6 , wherein the thermoplastic polymer is a (meth)acrylate copolymer.
8. The intumescent coating composition according to claim 7 , wherein the methacrylate copolymer comprises at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.
9. The intumescent coating composition according to claim 1 , wherein the thermoplastic polymer comprises as polymerized components: one or more dienes and at least one selected from the group consisting of styrene, vinyltoluene, vinyl chloride, vinyl acetate, vinylidene chloride and a vinyl ester.
10. The intumescent coating composition according to claim 1 , wherein the at least one ethylenically unsaturated monomer is a methacrylate or an acrylate monomer.
11. The intumescent coating composition according to claim 1 , wherein the at least one ethylenically unsaturated monomer is at least one monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2 hydroxyethyl (meth)-acrylate, 2-hydroxypropyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.
12. A process for curing the intumescent coating composition, according to claim 1 , comprising:
polymerizing the at least one ethylenically unsaturated monomer and the thermoplastic polymer wherein the polymerizing is a free radical polymerization.
13. The process for curing the intumescent coating composition according to claim 12 , wherein the free radical polymerization is initiated by an organic peroxide.
14. The process for curing the intumescent coating composition according to claim 13 , wherein the organic peroxide is selected from the group consisting of dialkyl peroxides, keto peroxides, peroxy esters, diacyl peroxides, hydroperoxides and peroxy ketals.
15. A coated substrate, comprising at least one surface coated with an intumescent coating obtained by curing the intumescent coating composition according to claim 1 , wherein the substrate is metal or wood.
16. The intumescent coating composition according to claim 1 , wherein the acid source is at least one selected from the group consisting of ammonium polyphosphate, a polyphosphoric acid, melamine phosphate, magnesium sulphate and boric acid.
17. The intumescent coating composition according to claim 1 , wherein the carbon source is at least one selected from the group consisting of pentaerythritol, dipentaerythritol, starch and expandable graphite.
18. The intumescent coating composition according to claim 1 , wherein the gas source is at least one selected from the group consisting of melamine, melamine phosphate, melamine borate, melamine-formaldehyde, melamine cyanurate, tris(hydroxyethyl)isocyanurate, ammonium polyphosphate and a chlorinated paraffin.
19. The intumescent coating composition according to claim 1 , wherein a content of the acid source, carbon source and gas source is 40%-85% by weight of the intumescent coating composition.