Multifilament polyester fibres

1. A multifilament fibre comprising

at least one polymer comprising a polyester, and

at least one filler comprising calcium carbonate, wherein the calcium carbonate is present in the multifilament fibre in an amount of at least 2 wt.-%, based on the total weight of the multifilament fibre and the calcium carbonate is a surface-treated calcium carbonate comprising on at least a part of its accessible surface area a treatment layer comprising a hydrophobising agent, where the hydrophobising agent is selected from a phosphoric acid ester blend of one or more phosphoric acid mono-ester and/or reaction products thereof and one or more phosphoric acid di-ester and/or reaction products thereof and mixtures thereof.

2. The multifilament fibre of claim 1 , wherein the polyester is selected from the group consisting of a polyglycolic acid, a polycaprolactone, a polyethylene adipate, a polyhydroxyalkanoate, a polyhydroxybutyrate, a polyalkylene terephthalate, a polyethylene terephthalate, a polytrimethylene terephthalate, a polybutylene terephthalate, a polyethylene naphthalate, a polylactic acid, or a mixture thereof, or copolymers thereof.

3. The multifilament fibre of claim 1 , wherein the polyester is a polyethylene terephthalate and/or a polybutylene terephthalate.

4. The multifilament fibre of claim 1 , wherein the calcium carbonate has a weight median particle size d50 from 0.1 to 3 μm.

5. The multifilament fibre of claim 1 , wherein the calcium carbonate is present in the multifilament fibre in an amount from 2 to 50 wt.-%, based on the total weight of the multifilament fibre.

6. The multifilament fibre of claim 1 , wherein the multifilament fibre has a linear mass density from 284 to 4000 dtex.

7. A textile article comprising at least one multifilament fibre according to claim 1 .

8. The textile article according to claim 7 , wherein said textile article is selected from construction products, consumer apparel, industrial apparel, medical products, home furnishings, protective products, packaging materials, cosmetic products, hygiene products, filtration materials, hoses, power belts, ropes, nets, threads, tire cords, auto upholsteries, sails, floppy disk liners, or fibrefills.

9. A process for producing a multifilament fibre comprising the steps of

a) providing a mixture comprising at least one polymer comprising a polyester and at least one filler comprising calcium carbonate,

b) melting the mixture of step a) and passing the same through shaped orifices to form a multifilament fibre, and

c) quenching the multifilament fibre,

wherein the calcium carbonate is present in the multifilament fibre in an amount of at least 2 wt.-%, based on the total weight of the multifilament fibre and the calcium carbonate is a surface-treated calcium carbonate comprising on at least a part of its accessible surface area a treatment layer comprising a hydrophobising agent, where the hydrophobising agent is selected from a phosphoric acid ester blend of one or more phosphoric acid mono-ester and/or reaction products thereof and one or more phosphoric acid di-ester and/or reaction products thereof and mixtures thereof.

10. The process of claim 9 , wherein the mixture of step a) is a mixture of a masterbatch and an additional polymer, wherein the masterbatch comprises at least one polymer comprising a polyester and at least one filler comprising calcium carbonate.

11. The process of claim 9 , wherein the process further comprises a step d) of drawing the multifilament fibre.

12. A process for producing a textile article comprising incorporating and/or manipulating at least one multifilament fibre according to claim 1 to produce the textile article.

13. The multifilament fibre according to claim 1 and/or a textile article comprising at least one multifilament fibre according to claim 1 , wherein the multifilament fibre and/or textile article is suitable for use in construction products, waterproofing, thermal insulation, soundproofing, roofing, consumer apparel, upholstery and clothing industries, industrial apparel, medical products, home furnishings, protective products, packaging materials, cosmetic products, hygiene products, filtration materials, agritechnical applications, building applications, geotechnical applications, industrial applications, medical applications, transporting, ecotechnical applications, packaging applications, personal protection, property protection, or sport applications.

14. The multifilament fibre of claim 1 , wherein the calcium carbonate has a weight median particle size d50 from 1.2 to 2.0 μm.

15. The multifilament fibre of claim 1 , wherein the calcium carbonate is present in the multifilament fibre in an amount from 10 wt.-% to 30 wt.-%, based on the total weight of the multifilament fibre.

16. The multifilament fibre of claim 1 , wherein the multifilament fibre has a linear mass density from 294 to 4000 dtex.

17. The process of claim 9 , wherein the mixture of step a) is a mixture of a masterbatch and an additional polymer, wherein the masterbatch comprises at least one polymer comprising a polyester and at least one filler comprising calcium carbonate, and in the masterbatch the calcium carbonate is present in an amount from 40 wt.-% to 75 wt.-%, based on the total weight of the masterbatch.

18. The process of claim 12 , wherein the incorporating and/or manipulating comprises layering, plaiting, braiding, knotting, weaving, knitting, crocheting, tufting, collecting on a surface or a carrier, bonding, thermal point bonding, calendering, ultrasonic bonding, hydroentanglement, needling, through-air bonding, dry laying, wet laying, direction orientation, creping, or embossing.

19. The multifilament fibre of claim 1 , wherein the multifilament fibre has a linear mass density from 403 to 1500 dtex.

20. The process of claim 9 , wherein the multifilament fibre has a linear mass density from 284 to 4000 dtex.