POLYMER, PROCESS AND COMPOSITION

1 . A copolymer having a low molecular weight and high glass transition temperature, the copolymer comprising (preferably consisting essentially of) moieties obtained and/or obtainable from the following components:

(a) at least 20 wt-% of one or more itaconate functional monomer(s) not containing acidic groups or precursor acid groups),

(b) not more than 40 wt-% of an acid functional monomer(s) in an amount sufficient to achieve an acid value from 65 to 325 mg KOH per g of solid polymer,

(c) optionally not more than 72 wt-% of other monomers not being either (a) or (b);

where the weight percentages of monomers (a), (b) and (c) total 100% and are calculated as a proportion of the total amount of monomers in the copolymer being 100%; and with the provisos:

(I) the copolymer has a number average molecular weight (M e ) of no more than 15 kilograms/mole (also referred to herein as tow MW'); and

(II) the copolymer has a glass transition temperature of at least 75° C. (also referred to herein as ‘High TG’),

and where either or both of provisos (III) and/or (IV) apply:

(III) the copolymer contains less than 40 wt-% vinyl aromatic monomer(s) (also referred to herein as ‘Low Vinyl Aromatic’ or Low-Styrene'); and/or

(IV) the copolymer contains less than 40 wt-% methacrylate monomer(s) (also referred to herein as ‘Low-MA’).

2 . A polymer composition as claimed in claim 1 , in which component (a) comprises a compound of Formula 1:

where Ra and Rb independently represent any optionally substituted hydrocarbo moiety (such as any aliphatic, cycloaliphatic or aromatic moieties); and

X and Y independently represent —O— and/or —NRc-, where Rc independently in each case represents H and/or any optionally substituted hydrocarbo moiety (such as any aliphatic, cycloaliphatic or aromatic moieties)

with the proviso that Formula 1 does not contain:

any acidic groups (such as carboxylic, phosphoric and/or sulphonic acid groups) or

any precursor acid groups, that is a group which readily generates an acid group under the conditions of polymerisation herein (such as an anhydride group).

3 . A polymer composition as claimed in claim 1 , in which component (b) is an acid functional monomer or precursor thereof selected form at least one ethylenically unsaturated carboxylic acid and/or derivatives thereof (such as anhydrides and/or salts).

4 . A polymer composition as claimed in claim 3 , in which the monomer composition is substantially free of arylalkylene and/or vinyl aromatic monomers.

5 . A polymer composition as claimed in claim 1 which is a solid grade oligomer (SGO).

6 . A process for preparing a polymer composition as claimed in claim 1 comprising the steps of:

(i) polymerising components (a), (b) and (c) (where present) in a solution polymerisation process in the presence of solvent,

(ii) removal of substantially all the solvent from step (i)

to obtain a copolymer comprising at least 95% solids.

7 . A process for preparing a polymer composition as claimed in claim 1 comprising the step of:

polymerising components (a), (b) and (c) (where present) in a bulk polymerisation process, where the bulk polymerisation is performed under at least one of the conditions (I) (II) and/or (III):

(I) in the presence of no more than 1 wt-% of chain transfer agent; relative to the total monomer composition (i.e. (a)+(b)+(c)) being 100%

(I) in the presence of no more than 1 mole-% of initiator; relative to the total monomer composition (i.e. (a)+(b)+(c)) being 100%; and/or

(III) with a maximum polymerisation temperature of no more than 250° C., preferably no more than 200° C.

8 . A polymer composition obtained and/or obtainable by a process as claimed in claim 6 .

9 . An aqueous composition comprising a polymer composition as claimed claim 1 and an aqueous medium.

10 . A coating composition comprising a polymer composition as claimed claim 1 .

11 . A substrate and/or article having coated thereon an (optionally cured) coating composition of claim 10 .

12 . A method of using a polymer composition as claimed in claim 1 to prepare a coating composition.

13 . A method for preparing a coated substrate and/or article comprising the steps of applying a coating composition of claim 10 to the substrate and/or article and optionally curing said composition in situ to form a cured coating thereon.

14 . A substrate and/or article obtained and/or obtainable by a method of claim 13 .