The present invention provides a dispersant of formula (1): T-V-(A)n, -U-Z-W, Formula (1) wherein, T is a polymerization terminating group; V is a direct bond or divalent linking group; A is the residue of one or more different hydroxy carboxylic acids or lactones thereof, U is a direct bond or a divalent linkage; Z is the residue of a polyamine or polyimine; W is the residue of an oxide or urea; m is from 2 to 2000; and x is from 1 up to the maximum number of available amino and/or imino groups in Z which do not carry the group T-V-(A) n , -U-.
1. A polyester amine dispersant of formula (1):
wherein,
T-V-(A) m -U- is a polyester chain
T is a polyester polymerisation terminating group containing R—C(═O)— or R—O— where R is a C 1 to C 20 hydrocarbyl group and T is derived from an ester forming reaction of a carboxylic acid or an alcohol;
V is a direct bond connecting T to (A) m ;
A is an oxyalkylenecarbonyl unit derived from one or more different hydroxyl-C 2-20 -alkenylene carboxylic acids or hydroxyl-C 1-20 -alkylene carboxylic acid or lactones thereof forming a polyester segment (A) m ;
U is a direct bond or a divalent linkage of the structure —CH 2 —CH(R 2 )—C(═O)—O—R 3 —O— wherein R 2 is hydrogen or methyl and R 3 is ethyl and being the residue of hydroxyethyl(meth)acrylate linking Z to (A) m ;
Z is polyvinylamine, polyallylamine or a poly(C 2-4 -alkyleneimine) of number average molecular weight of 1,000 to 100,0000 g/mole that has been linked to (A) m via U;
W is the reaction product of an amino or imino group of Z with a) urea at 100 to 150° C. or b) oxygen to form an N-oxide;
m is from 2 to 2000; and
x is from 1 up to the maximum number of available amino and/or imino groups in Z which do not carry the group T-V-(A) m -U-.
2. A dispersant as claimed in claim 1 wherein T is derived from an ester forming reaction of a carboxylic acid R—COOH with (A) m .
3. A dispersant as claimed in claim 2 wherein R is an alkyl which may be linear or branched.
4. A dispersant as claimed in claim 1 wherein A comprises an oxyalkylenecarbonyl repeat unit derived from 12-hydroxy stearic acid or ricinoleic acid reacted in a polyester polymerization.
5. A dispersant as claimed in claim 1 wherein the oxyalkylenecarbonyl repeat unit of (A), comprises the reaction product of ester polymerization of ε-caprolactone.
6. A dispersant as claimed in claim 1 wherein m is not greater than 20.
7. A dispersant as claimed in claim 1 wherein Z comprises polyvinylamine, polyallylamine or a poly(C 2-4 -alkyleneimine) carrying at least two chains of formula (3):
wherein, T, V, A, U and m are as defined in claim 1 .
8. A dispersant as claimed in claim 7 wherein the dispersant is represented by formula (4):
wherein,
X-*-*-X represents polyvinylamine, polyallylamine or poly(C 2-4 -alkyleneimine);
each Y represents the polyester chain T-V-(A) m -U which may be the same or different and is linked to X-*-*-X via an amide and/or salt linkage;
r is from 2 to 2000; and
T, V, A, U and m are as defined in claim 1 .
9. A dispersant as claimed in claim 8 wherein the weight ratio of X-*-*-X to Y is from 20:1 to 2:1.
10. A dispersant as claimed in claim 8 wherein Y represents a chain residue of formula (5):
wherein,
R 2 is hydrogen or C 1-4 -alkyl; and
R 3 is an aliphatic or aromatic residue containing up to 10 carbon atoms which optionally contains a polyether derived from propylene oxide and/or ethylene oxide.
11. A process for making a dispersant of formula 1 of claim 1 comprising reacting T-V-(A) m -U- with Z and then reacting imino or amino groups of Z, which do not carry the group T-V-(A) m -U-, with urea at a temperature from 100° C. to 150° C.
12. A composition comprising a particulate solid and a dispersant as claimed in claim 1 .
13. A composition as claimed in claim 12 which further comprises an organic liquid.
14. A millbase, paint or ink which comprises a particulate solid, organic liquid, film-forming binder resin and a dispersant as claimed in claim 1 .