FIREPROOF POLYAMIDE ARTICLE INCLUDING A COATING FORMED BY PLASMA TREATMENT
Polyamide articles are described, in particular molded fireproof articles, including a coating deposited using cold plasma. The articles can have excellent flame properties, and can include, in the polyamide matrix, at least one fireproofing system and have such a coating on at least one of the surfaces thereof.
1 . A flame-retardant article, the article comprising a polyamide composition comprising at least one flame retardant system, wherein the article further comprises, at least over a portion of its surface, a coating produced by cold-plasma-enhanced chemical deposition.
2 . The flame-retardant article as defined by claim 1 , wherein the composition additionally comprises reinforcing fillers.
3 . The flame-retardant article as defined by claim 1 , wherein the flame retardant system of the polyamide composition comprises at least one flame retardant selected from the group consisting of: phosphine oxides, phosphonic acids or salts thereof, phosphinic acids or salts thereof, cyclic phosphonates, organic phosphates, inorganic phosphates and red phosphorus.
4 . The flame-retardant article as defined by claim 1 , wherein the flame retardant system of the polyamide composition comprises at least one flame retardant selected from the group consisting of: triazines, cyanuric acid and/or isocyanuric acid, melamines, melamine oxalate, phthalate, borate, sulfate, phosphate, polyphosphate and/or pyrophosphate, products condensed from melamine, tris(hydroxyethyl) isocyanurate, benzoguanamine, guanidine, allantoin and glycoluril.
5 . The flame-retardant article as defined by claim 1 , wherein the flame retardant system of the polyamide composition comprises at least one flame retardant selected from the group consisting of: PBDPOs (polybromodiphenyl oxides), BrPS (polybromostyrene and brominated polystyrene), poly(pentabromobenzyl acrylate), brominated indane, tetradecabromodiphenoxybenzene, 1,2-bis(pentabromophenyl)ethane, tetrabromobisphenol A and brominated epoxy oligomers.
6 . The flame-retardant article as defined by claim 1 , wherein the composition comprises from 5% to 40% by weight of flame retardants, with respect to the total weight of the composition.
7 . The flame-retardant article as defined by claim 1 , wherein the composition comprises from 1% to 50% by weight of reinforcing fillers, with respect to the total weight of the composition.
8 . The flame-retardant article as defined by claim 1 , wherein the coating is produced by cold-plasma-enhanced chemical deposition at a temperature of between 20° C. and 350° C.
9 . The flame-retardant article as defined by claim 1 , wherein the coating is produced by cold-plasma-enhanced polymerization techniques, under reduced pressure or atmospheric pressure.
10 . The flame-retardant article as defined by claim 1 , wherein the coating is produced by cold-plasma-enhanced chemical deposition via PECVD (plasma-enhanced chemical vapor deposition).
11 . The flame-retardant article as defined by claim 1 , wherein the chemical deposition has an SiO 2 inorganic structure and/or a siloxane and/or polysiloxane organic structure.
12 . The flame-retardant article as defined by claim 1 , wherein the coating on the surface of the article has a thickness of between 1 μm and 200 μm.
13 . The flame-retardant article as defined by claim 1 , wherein the coating on the surface of the article has a thickness of between 8 μm and 20 μm.
14 . The flame-retardant article as defined by claim 1 , wherein said article is an extruded or injected article.
15 . A process for the manufacture of a flame retardant article, the process comprising applying a coating by cold-plasma-enhanced chemical deposition over at least a portion of a surface of the article obtained by forming a polyamide composition comprising at least one flame retardant system, in particular after a surface treatment step has been carried out in order to increase adhesion between the surface and the coating.
16 . The process as defined by claim 15 , wherein the compounds used for making the coating produced by cold-plasma-enhanced chemical deposition are selected from the group consisting of: tetramethyldisiloxane, hexamethyldisiloxane, octamethylcyclotetrasiloxane, and tetraethoxysilane.
17 . The flame retardant article as defined by claim 7 , wherein the reinforcing fillers are present in an amount from 15% to 50% by weight.