Polymeric materials

1. A method of making a fibre comprising a polymeric material and at least one additive, the method comprising:

A) selecting a liquid formulation comprising at least one additive and a vehicle comprising an aromatic tri-carboxylic acid covalently linked by ester bonds to two or more chains, wherein said chains comprise linear or branched alkyl groups with between 7 and 10 carbon atoms, wherein said formulation contains a total amount of from 39 to 60 wt % of additives and at least 20 wt % of vehicle, and said at least one additive is selected from colourants, stabilizers, delusterants, anti-static agents, optical brighteners, processing aids, light reflective additives, anti-soil additives, friction modifiers, antioxidants, and anti-flammability additives;

B) contacting the liquid formulation with said polymeric material in a melt processing apparatus;

wherein said carboxylic acid is of general formula:

where R 9 , R 10 and R 11 represent a hydrogen atom;

wherein the total amount of additives introduced into said polymeric material via said formulation in the method is at least 0.05 wt % and is less than 4 wt %;

wherein the total amount of vehicle introduced into said polymeric material via said formulation in the method is at least 0.0125 wt % and is less than 4 wt %;

wherein downstream of the point of contact of liquid formulation and polymeric material there is provided a spinning means for spinning the polymeric material to define fibres; and

wherein said polymeric material comprises a polyester.

2. A method according to claim 1 , wherein said chains are unsubstituted and include 7 to 10 carbon atoms; and wherein said vehicle is a trimellitate.

3. A method according to claim 1 , wherein said vehicle has a boiling point of greater than 285° C., and a molecular weight in the range 500 to 4200 g/mol.

4. A method according to claim 1 , wherein said liquid formulation is dosed into said polymeric material when the polymeric material is in a molten state, and said liquid formulation is injected at a pressure in the range 5 to 120 bar into the polymeric material, wherein a mixing means is provided for facilitating mixing of the liquid formulation and polymeric material.

5. A method according to claim 4 , wherein said mixing means comprises a cavity transfer mixer.

6. A method according to claim 1 , wherein said ester-containing vehicle is formed by reacting a selected tri-carboxylic acid with alkyl-containing moieties to provide the alkyl groups.

7. A method according to claim 1 , wherein said vehicle has a viscosity of between 100,000 cP and 1,000 cP.

8. A method according to claim 1 , wherein said polyester has an IV in the range of 0.5 to 1.2 dl/g.

9. A method according to claim 1 , wherein said vehicle comprises a trimellitate, has a boiling point of greater than 285° C., and a molecular weight in the range of 500 to 4,200 g/mol; and wherein said polyester has an IV in the range of 0.5 to 1.2 dl/g.

10. A method according to claim 9 , wherein said at least one additive is a colourant.

11. A method according to claim 10 , wherein the total amount of vehicle introduced into said polymeric material via said formulation in the method is at least 1 wt %; and wherein said at least one additive is a colourant.

12. A method according to claim 1 , wherein said vehicle comprises a trimellitate; wherein said polyester has an IV within the range of 0.5 to 1.2 dl/g; and wherein said at least one additive is a colourant.

13. A method according to claim 1 , wherein at least 2 wt % of said liquid formulation is contacted with said polymeric material in the method.

14. A method according to claim 1 , wherein said liquid formulation is dosed into said polymeric material when the polymeric material is in a molten state.

15. A method according to claim 1 , wherein the total amount of vehicle introduced into said polymeric material via said formulation in the method is at least 1 wt %; wherein said at least one additive is a colorant; wherein said vehicle comprises a trimellitate; wherein said polyester has an IV within the range 0.5 to 1.2 dl/g; and wherein said liquid formulation is dosed into said polymeric material when the polymeric material is in a molten state.

16. A method according to claim 15 , wherein at least 2 wt % of said liquid formulation is contacted with said polymeric material in the method.

17. A method according to claim 14 , wherein said polymeric material which is contacted in the method is supplied directly from a reactor in which the polymeric material is made in a polymerisation reaction.