Water-thinnable polymer precursors, their preparation and use
The present invention is directed towards water-thinnable phosphorous-containing polymers precursors, their preparation and use. The precursors of the invention are useful in compositions for preparing coatings which impart and/or exhibit resistance to attack, for example which are useful as flame-retardant coatings.
1. A process for preparing a water-thinnable phosphorous-containing polymer precursor which polymer precursor is a polyester, which process comprises the steps of
(a) providing a polyester which comprises a plurality of di- or polycarboxylic acid residues and a plurality of di- or polyol residues and which comprises phosphinate ester (P—O—C) bonds and
(b) hydrolysing at least part of said phosphinate ester (P—O—C) bonds.
2. A process as claimed in claim 1 , in which at least part of said phosphinate ester (P—O—C) bonds are hydrolyzed selectively without hydrolyzing the polyester backbone of the polymer precursor.
3. A process as claimed in claim 1 , in which at least part of said phosphinate ester (P—O—C) bonds are hydrolyzed in the presence of an alcoholic solvent.
4. A process as claimed in claim 3 , in which the alcoholic solvent is selected from straight, branched or cyclic, saturated or unsaturated C 1-6 -alkanols and in particular from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and tert.-butanol.
5. A process as claimed in claim 1 , in which at least part of said phosphinate ester (P—O—C) bonds are hydrolyzed in the presence of a base.
6. A process as claimed claim 1 , in which the polyester comprises at least two (meth)acrylate groups.
7. A process as claimed in claim 1 , in which the polymer precursor is a radiation-curable polyester, the process comprising the steps of
(a) mixing together:
(i) a compound containing at least one hydrocarbylidenically unsaturated group and a plurality of carbonyloxy groups;
(ii) optionally a compound having a plurality of carbonyloxy groups and optionally free of hydrocarbylidenically unsaturated groups;
(iii) a polyol, and
(iv) an oxyphosphorous-containing compound (component (iv)) in which the phosphorous atom has at least one P—C bond and at least one P—O—C moiety which are resistant to hydrolysis or transesterification under the reaction conditions under steps (b) and (c); such component (iv) comprising a compound of formula (I) and/or effective isomers, salts and
mixtures thereof:
where, in formula (I): the phosphorous atom is substituted with at least one carbon atom to form at least one P—C bond; the P—O bond forms part of an organo ring, the ring being optionally substituted with one or more organo groups and/or optionally fused to one or more other organo rings;
(b) initiating polymerization of the mixture to form a hydroxy and/or carboxy terminated phosphorous containing polyester oligomer (“First Polymer”),
(c) reacting the First Polymer with at least one acrylating agent to form a radiation-curable polymer precursor (“Second Polymer”),
(d) hydrolyzing at least part of the phosphinate ester (P—O—C) bonds in the Second Polymer.
8. A process as claimed in claim 7 , in which component (IV) comprises a compound of formula II where
R 1 R 2 R 3 P═O
in formula (II): at least R 1 and R 2 independently represents C 1-20 organo group substituted by one or more hydroxy and/or carboxy group; R 3 represents H or optionally substituted C 1-20 organo group.
9. A process as claimed in claim 1 , in which said phosphinate ester (P—O—C) bonds are in the side chain(s) of the polyester and the phosphorous atom of said phosphinate ester (P—O—C) bonds forms part of the backbone of said polyester or is directly or indirectly bonded to the backbone of said polyester via a bond which is not said phosphinate ester (P—O—C) bond.
10. A process as claimed in claim 1 , in which the polyester comprises 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide residues.
11. A water-thinnable phosphorous-containing polymer precursor obtained from the process as claimed in claim 1 .
12. A flame-retardant composition comprising a polymer precursor as claimed in claim 11 .
13. A flame-retardant coating comprising a flame-retardant layer over a substrate (layer ( 1 )) which layer is obtained by curing a composition as claimed in claim 12 .
14. A flame-retardant coating as claimed in claim 13 , comprising at least one other layer (layer ( 2 )) over the flame retardant coating, said other layer containing optionaly sublayers ( 2 a , 2 b . . . ).
15. A flame-retardant coating as claimed in claim 14 , in which at least layer ( 2 ) is transparent.
16. A flame-retardant coating as claimed in claim 14 , in which layer ( 2 ) imparts abrasion-resistance to the coating.
17. A flame-retardant coating as claimed claim 14 , in which the layer ( 2 ) contains at least one flame-retardant sublayer.
18. Method for preparing a flame-retardant composition which comprises employing the polymer precursor of claim 11 .
19. Method for coating a substrate which comprises applying to the substrate, the flame retardant composition of claim 12 .
20. A substrate at least part of which is coated with a coating as claimed in claim 13 .
21. A coated substrate according to claim 20 , which substrate comprises wood, textile, fiber, metal or plastics.
22. The process as claimed in claim 5 wherein the base is a strong base.