The invention relates to polyesters and particularly, although not exclusively, relates to dyeing of polyester fibre and textiles produced from polyester fibre.

Polyesters, especially polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) have a wide range of uses, with one use being in manufacture of fibres which are, in turn, used to manufacture textiles, for example clothing.

Textiles need to be available in a range of colours which means that polyester needs to be subjected to a colouring process which generally involves dyeing the polyester.

However, in polyester, for example PET, there are no dye sites in the molecular chains which makes it difficult to dye it. In addition, PET is a semi-crystalline polymer which also contributes to difficulties in dyeing the polymer as the dyeing process typically is done at high temperature of 130°C.

Steps to address the aforementioned problems may involve use of polyesters which have lower levels of crystallinity and/or include higher levels of amorphous regions. However, such modified polyesters may detrimentally affect the physical and/or chemical properties of the polyester itself.

It is also known to introduce functionality into polyester to make it have a higher affinity for cationic dyes, with the aim of then extruding and spinning that functionalised polyester to produce fibres. For example, a polyester polymer may be made with a sulfonic acid-containing monomer, thereby to incorporate sulfonate groups into the polyester and thereby increase the affinity of the polyester to cationic dyes. However, introduction of such monomers may disadvantageously lead to polymer chain breakage and lower IV. Furthermore, there is little scope to select and/or adjust functional additives included in the polyester. In addition, use of sulfonic acid-containing copolymers reduces the flexibility of being able to adjust IV to improve fiber physical properties.

It is an object of the present invention to address the above-described problems.

It is an object of the present invention to address problems of dyeing polyesters, especially PET, PBT and their recycled materials.

According to a first aspect of the invention, there is provided a composition for use in producing a dyeable polyester, the composition comprising: (i) a sulfopolyester; and

(ii) a carrier polymer which is preferably a polyethylene terephthalate (PET) based polyester or a polybutylene terephthalate (PBT) based polyester.

Solid sulfopolyester suitably includes a repeat unit comprising a phenyl moiety substituted by a moiety -SOs’. Said phenyl moiety may be substituted by a at least two carbonyl moieties which are suitably derived from carboxylic acid or carboxylic acid derivative groups.

Said sulfopolyester suitably includes a repeat unit which includes a moiety:

Preferably, the carbonyl moieties in moiety I are meta to one another. Preferably, the -SOs" moiety is meta to one or preferably both C=O moieties.

Said sulfo polyester preferably includes a repeat unit which includes a moiety:

In moieties I and/or II, a counter-ion to the -SOs moiety may be a Group I metal cation, preferably Na ⁺ .

Said sulfo polyester preferably includes a monosodium-5-sulfoisophthalate repeat unit. Said sulfo polyester is suitably a polyester made by polymerising diacid and dialcohol monomers. Preferably, in said sulfopolyester, the mole% of moieties derived from diacids which include unit I and/or II is in the range 1 to 20 mole %, more preferably in the range to 2 to 15 mole %; or is in the range 3 to 10 mole %, wherein the sum of the mol % of moieties derived from diacids is suitably taken to be 100 mole %.

Said sulfo polyester may include a repeat unit derived from a dialkylene glycol for example a C1- 6 dialkylene glycol.

Said sulfo polyester preferably includes acid moiety repeat units derived from isophthalic acid, terephthalic acid and/or phthalic acid in combination with 5-sulfoisophthalic acid. Preferably, said sulfo polyester includes acid moiety repeat units derived from isophthalic acid and 5- sulfoisophthalic acid.

Said sulfo polyester preferably includes hydroxy moiety repeat units derived from 1 ,4- cyclohexanone, dimethanol and/or diethylene glycol. Said sulfo polyester preferably includes hydroxy moiety repeat units derived from each of 1 ,4-cyclohexanone, dimethanol and diethylene glycol.

Preferably, said sulfopolyester contains substantially equimolar proportions of acid moiety repeating units (100 mole %) to hydroxy moiety repeating units (100 mole %), the sulfo polyester comprising repeating units of components (a), (b), (c) and (d), as follows wherein all stated mole percentages are based on the total of all acid and hydroxy moiety repeating units being equal to 200 mole %:

(a) about 90 to about 97 mole % isophthalic acid,

(b) about 3 to about 10 mole % 5-sulfoisophthalic acid,

(c) about 70 to about 85 mole % 1 ,4-cyclohexanedimethanol, and

(d) about 15 to about 30 mole % diethylene glycol.

The term "repeating unit" of a particular component in the sulfopolyester means that repeating unit of the particular component known in the art to be incorporated into a polyester. Thus, a "1 ,4-cyclohexanedimethanol repeating unit" is a moiety of the structure:

An "isophthalic acid repeating unit" is a moiety of the structure

A "5-sulfoisophthalic acid repeating unit" is of the structure:

A "diethylene glycol repeating unit" is of structure:

Therefore, any chemical derivative which will result in the desired repeating unit can be used to prepare the sulfo polyester. For example, the corresponding acid anhydrides, esters, and acid chlorides (as well as the free diacids themselves) can be used as the particular starting material for incorporating the desired dicarboxylic acid repeating unit into the polyester. The total amount of acid moiety repeating units in the sulfopolyester is 100 mole %. The acid moiety repeating unit in the sulfo polyester are components (a) and (b); therefore, the total mole percentage of components (a) plus (b) in the sulfopolyester is 100 mole %. Likewise, the total amount of hydroxy moiety repeating units in the sulfo polyester is 100 mole %. The hydroxy moiety repeating units in the sulfopolyester are components (c) and (d); therefore, the total mole percentage of components (c) plus (d) in the sulfopolyester is 100 mole %. It follows then that the total of all acid moiety and hydroxy moiety repeating units in the sulfopolyester totals 200 mole %.

In the sulfopolyester, component (b), i.e., the 5-sulfoisophthalic acid, is typically in the form of a metallic sulfonate salt.

The inherent viscosities (I.V.) of the particular sulfopolyester are suitably at least about 0.1 as determined according to ASTM D2857-70 procedure, in a Wagner Viscometer of lab Glass, Inc., of Vineland, N.J., having a 1/2 mL capillary bulb, using a polymer concentration of about 0.5% by weight in 60/40 by weight of phenol/tetrachloroethane. It is preferred that the I.V. of the sulfo polyester is about 0.1 to about 1 .0, more preferably about 0.2 to about 0.6. The procedure for determining I.V. is carried out by heating the polymer/solvent system at 120 °C for 15 minutes, cooling the solution to 25°C and measuring the time of flow at 25°C.

Unless otherwise stated, as used herein, particularly in the context of the carrier polymer, the term “IV” refers to the Intrinsic Viscosity of the polymeric material. It may be determined on a solution of 0.5 g of polymer dissolved in 100 ml of a mixture of phenol (60% by volume) and tetrachloroethane (40% by volume). It is suitably determined as described in ASTM D4603-18, the content of which is incorporated herein by way of reference.

Said carrier polymer suitably has an IV of greater than 0.5 dL/g, more preferably greater than 0.65 dL/g. The IV may be less than 0.85 dL/g, for example less than 0.81 dL/g.

Said carrier polymer may be a low melting polyester polymer, for example having a melting point of at least 165°C or at least 173°C, for example, in the range 165 to 185°C; or may have a melting point in the range 250 to 280°C.

Said carrier polymer suitably includes residues (A) of one or more dicarboxylic acids and residues (B) of one or more diols. Ester linkages are suitably defined between residues (A) and (B). Suitably, said carrier polymer is made by esterifying a dicarboxylic acid or ester (which produces residues (A)) and a diol (which produces residue (B)).

Said carrier polymer suitably includes a least 30 mol%, preferably at least 40 mol%, more preferably at least 45 mol% of residues (A). Said carrier polymer suitably includes a least 30 mol%, preferably at least 40 mol%, more preferably at least 45 mol% of residues (B).

Residues (A) preferably include a moiety

The floating bond in moiety III may be bonded to the benzene ring at the ortho position (so the moiety comprises a phthalic acid residue), at the meta position (so the moiety comprises an isophthalic acid residue) or at the para position (so the moiety comprises a terephthalic acid residue).

Residues (A) preferably comprise terephthalic acid residues. Preferably, at least 60wt%, at least 75wt%, at least 90wt% or at least 95 wt% of residues (A) which include moiety III are terephthalic acid residues. In some cases, about 100wt% of residues (A) are terephthalic acid residues.

When said carrier polymer includes residues (A) of one or more dicarboxylic acids which include moiety III and residues of other dicarboxylic acids, the other dicarboxylic acids may be selected from naphthalene-2,6-dicarboxylic acid, cyclohexanedicarboxylic acid, cyclohexanediacetic acid, diphenyl-4,4'-dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid and sebacic acid. However, said carrier polymer suitably includes less than 5wt% or less than 1wt% of said residues of other dicarboxylic acids. Said carrier polymer suitably includes 0wt% of said residues of other dicarboxylic acids.

Preferably, said residues (A) do not include any polymeric chain or repeat unit.

Residues (B) preferably include a moiety

0-(CH2 n-O

IV wherein n is in the range of 1 to 6. Preferably, n is in the range of 2 to 4 and is preferably 2 or 4. Thus, residues (B) are preferably ethylene glycol residues or butylene glycol residues.

Preferably, residues (B) comprise ethylene glycol residues or butylene glycol residues. Preferably, at least 60 wt%, at least 75 wt%, at least 90 wt% or, especially, at least 95 wt% of residues (B) include moiety IV and/or consists of ethylene glycol residues or butylene glycol residues. In some, preferred, cases, about 100 wt% of residues (B) comprise ethylene glycol residues or butylene glycol residues.

Preferably, at least 60 wt%, at least 75 wt%, at least 90 wt% or, especially, at least 95 wt% of residues (B) include moiety IV and/or consist of ethylene glycol residues; or at least 60 wt%, at least 75 wt%, at least 90 wt% or, especially, at least 95 wt% of residues (B) include moiety IV and/or consist of butylene glycol residues.

Residues (B) preferably include a moiety IV wherein n is 2 and/or residues (B) are ethylene glycol residues. Preferably, at least 60 wt%, at least 75 wt%, at least 90 wt% or, especially, at least 95 wt% of residues (B) include moiety IV and/or consist of ethylene glycol residues. In some, preferred cases, about 100 wt% of residues (B) comprise ethylene glycol residues.

When said carrier polymer includes residues (B) of one or more diols which include moiety IV and residues of other diols, the other diols may be selected from diethylene glycol, triethylene glycol, 1 ,4-cyclohexanedimethanol, propane-1 ,3-diol, butane-1 ,4-diol, pentane-1 ,5-diol, hexane- 1 ,6-diol, 3-methylpentane-2,4-diol, 2-methyl pentane-1 ,4-diol, 2,2,4-trimethylpentane-1 ,3-diol, 2-ethylhexane-1 ,3-diol, 2, 2-diethylpropane-1 ,3-diol, hexane-1 ,3-diol, 1 ,4-di(hydroxyethoxy)- benzene, 2,2-bis-(4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1 ,1 ,3,3-tetramethyl- cyclobutane, 2,2-bis-(3-hydroxyethoxyphenyl)-propane, and 2,2-bis-(4-hydroxypropoxyphenyl)- propane. However, said carrier polymer suitably includes less than 5wt% or less than 1wt% of said residues of other diols. Said carrier suitably includes 0wt% of said residues of other diols.

Preferably, said residues (B) do not include any polymeric chain or repeat unit.

Preferably, in the carrier polymer, the sum of the wt% of residues (A) and residues (B) is at least 75 wt%, is preferably at least 85 wt%, is more preferably at least 95% and, especially, is at least 99wt%.

In a preferred embodiment, said carrier polymer is not a co-polyethylene terephthalate; it suitably comprises substantially a homopolymer produced by esterification or transesterification of terephthalic acid or dimethyl terephthalate and ethylene glycol or butylene glycol to produce bis(2-hydroxyethyl) terephthalate or bis(2-hydroxybutyl) terephthalate which is then subjected to polycondensation at high temperatures in vacuum in the presence of a catalyst.

Preferably, in the carrier polymer, the sum of the wt% of residues (A) which are terephthalic acid residues and residues (B) which are ethylene glycol residues or butylene glycol residues, is at least 75 wt%, is preferably at least 85 wt%, is more preferably at least 95% and, especially, is at least 99wt%. Preferably, in the carrier polymer, the sum of the wt% of residues (A) which are terephthalic acid residues and residues (B) which are ethylene glycol residues, is at least 75 wt%, is preferably at least 85 wt%, is more preferably at least 95% and, especially, is at least 99wt%.

Said carrier polymer may comprise virgin polyester or recycled polyester of the types described. Said carrier polymer may comprise virgin PET or virgin PBT; or recycled PET (rPET) or recycled PBT (rPBT). Preferably, said carrier polymer is virgin PET or recycled PET (rPET).

In said composition of the first aspect, the sum of the wt% of one or more sulfo polyesters and one or more carrier polymers is suitably at least 80 wt%, preferably at least 90 wt%, especially at least 95 wt%. Said sum may be at least 98 wt%.

In said composition of the first aspect, the sum of the wt% of one sulfo polyester and one carrier polymer is suitably at least 80 wt%, preferably at least 90 wt%, especially at least 95 wt%. Said sum may be at least 98 wt%.

In one embodiment, said composition may include 5-99wt% of sulfopolyester. Said composition of the first aspect preferably includes at least 50 wt%, preferably 50-70 wt% of one or more, preferably a single type, of sulfopolyester.

Said composition of the first aspect may include at least 30 wt% of carrier polymer, for example a PET-based or PBT-based carrier polymer. Said composition of the first aspect may include at least 30 wt% of one type of carrier polymer, for example a PET-based or a PBT-based polymer. Said composition may include 30-50 wt% of carrier polymer, for example a single type of carrier polymer.

Said composition of the first aspect may include 0 -10wt%, preferably 0-5 wt%, for example 0- 2 wt%, of one or more other additives, for example functional additives which may be selected from chain extenders, impact modifiers, nucleating agents, UV stabilizers, anti-oxidants and flame retardants. Said composition may include at least 0.1 wt% of at least one functional additive, for example at least one of the specified functional additives.

In one embodiment, said composition may include a nucleating agent, for example a talc. Such a composition may include up to 28wt% or up to 16wt% of nucleating agent. A nucleating agent may be selected to increase crystallisation rate in use.

Said composition is preferably a solid masterbatch which is preferably in the form of pellets. Alternatively, said composition may be a dry blend comprising said sulfopolyester and said carrier polymer. According to a second aspect of the invention, there is provided a method of improving the dyeability, preferably with cationic dyes, of bulk polyester, the method comprising:

(i) selecting a composition of the first aspect;

(ii) contacting said composition with bulk polyester.

The ratio of the wt% of said composition selected divided by the wt% of said bulk polyester may be in the range 0.05-0.45, preferably in the range 0.15 to 0.35. In a preferred embodiment, 10- 30 wt% of said composition of the first aspect may be contacted with 70-90 wt% of said bulk polyester. Preferably, 15-25 wt% of said composition of the first aspect is contacted with 75-85 wt% of said bulk polyester.

The method of the second aspect preferably comprises melt-processing said composition and bulk polyester, for example in an extruder.

The method may comprise extruding a mixture comprising said composition of the first aspect and bulk polyester to prepare extruded fibre.

Said bulk polyester may comprise virgin polyester or recycled polyester. Said bulk polyester may comprise virgin PET or virgin PBT; or recycled PET (rPET) or recycled PBT (rPBT). Preferably, said bulk polyester is virgin PET or recycled PET (rPET). Advantageously, the dyeability of recycled polyesters may be improved. Thus, said bulk polyester preferably includes at least 5wt%, at least 10wt%, at least 20wt%, at least 35wt%, or at least 45wt%, of recycled polyester, for example recycled PET or PET. Said bulk polyester preferably includes at least 5wt% recycled PET.

Said bulk polyester suitably has an IV of greater than 0.5 dL/g, more preferably greater than 0.50 dL/g. The IV may be less than 0.85 dL/g, for example less than 0.80 dL/g or less than 0.70 dL/g.

According to a third aspect of the invention, there is provided a mixture comprising a composition of the first aspect and bulk polyester wherein, preferably, said mixture is made in the method of the second aspect.

In said mixture, preferably, the ratio of the wt% of said composition of the first aspect divided by the wt% of said bulk polyester is in the range 0.05-0.45, preferably in the range 0.15 to 0.35. In a preferred embodiment, said mixture includes 10-30 wt% of said composition of the first aspect and 70-90 wt% of said bulk polyester. Preferably, said mixture comprises 15-25 wt% of said composition of the first aspect and 75-85 wt% of said bulk polyester.

According to a fourth aspect of the invention, there is provided a method of making spun fibre, suitably with improved dyeability, the method comprising:

(i) selecting a mixture comprising a composition of the first aspect and bulk polyester as described in the second or third aspects and/or providing a mixture of the third aspect; and

(ii) extruding the mixture and drawing it to produce extruded fibre.

According to a fifth aspect of the invention, there is provided spun fibre with improved dyeability, the fibre comprising: a mixture of a composition of the first aspect and bulk polyester as described in the second and third aspects; or a mixture of the third aspect.

According to a sixth aspect of the invention, there is provided a method of dyeing bulk polyester, the method comprising:

(i) selecting a mixture of a composition of the first aspect and bulk polyester as described in the second and third aspects; or selecting a mixture of the third aspect; and

(ii) contacting the mixture with a dye.

Said dye is preferably a cationic dye. Cationic dyes are suitably dyes that can be dissociated into positively charged ions in aqueous solution. They can interact with the negative group on the sulfopolyester to form a salt, so the mixture is dyed. Said cationic dye is suitably an alkaline dye. Said cationic dye may be an azo dye, a methine dye, an anthraquinone dye and/or comprise a heterocyclic compound. The cationic portion of the dye suitably includes an onium moiety which may form a salt with a -SOs" moiety. The cations may include N+ ions. The dye may be water-soluble. Said dye may be selected from: ASTRAZON PINK FG, ASTRAZON RED 6B, ASTRAZON BRILLIANT RED 4G, BASIC YELLOW 11 , Cationic Orange G, Cationic Black O, BASIC RED 29, BASIC YELLOW 28, Cationic Yellow X-8GL, Basic Blue 159, Brilliant Red B, BASIC ORANGE 21 , 2-[2-[4-(diethylamino)phenyl]vinyl]-1 ,3,3-trimethyl-3H-indolium chloride, Cationic Red B, Cationic Black X-O, Cationic Blue GL, TAIACRYL BLUE AD-GSLNT, Turquoise Blue X-GB, Black X-FBL, Cationic starch, BASIC BLUE 41 (C. I. 11105), BASIC BLUE 4, Catonic Black XL, BASIC RED 18:1 , Cationic Red 6B, BASIC BLUE 3, Basic Yellow 21 , Cationic Red x- GRL, 3-(3-amino-3-oxopropyl)-2-[[1-methyl-2-(p-tolyl)-1 H-indol-3-yl]azo]benzothiazolium chloride, Catonic Black L and Flavine 10GFF.

Said dye may be provided in aqueous solution, for example including at least 95 wt% or at least 99 wt% water. The solution may be acidic.

Dyeing may be undertaken at an elevated temperature, for example at greater than 80°C; and, preferably, at less than 200°C, more preferably, at less than 150°C.

Preferably, in the method of the sixth aspect, spun fibre as described in the fourth and/or fifth aspects is dyed.

According to a seventh aspect of the invention, there is provided dyed spun fibre, the fibre being dyed as described in the sixth aspect and/or being spun fibre comprising:

(i) bulk polyester as described in the second and/or third aspects;

(ii) a sulfopolyester as described in the first aspect;

(iii) a carrier polymer as described in the first aspect;

(iv) dye, for example a cationic dye.

Any feature of any aspect of any invention or embodiment described herein may be combined with any feature of any other aspect of any invention or embodiment described herein mutatis mutandis.

Specific embodiments of the invention will now be described, by way of example.

The following materials are referred to hereinafter:

Eastman AQ™ 55S polymer - refers to polyeser-5, in pellet form, CAS No.54590-72-6, a sulfo polyester obtained from Eastman and having the following properties:

Eastion PET CB-602 - refers to polyethylene terephthalate-isophthalate), a condensation polymer produced from pure terephthalic acid (PTA), isoterephthalic acid (IPA) and ethylene glycol (EG), obtained from Far Eastern Textile Ltd and having the following properties:

PET CMFC - refers to polyethylene terephthalate-isophthalate), obtained from China Manmade Fiber Corp (CMFC) and having an intrinsic viscosity IV=0.6 dL/g; Low melting PET - refers to a PET having a melting point of 176°C and an IV of 0.676 dL/g;

TAIACRYL BLUE AD-GSLNT - a cationic dye; JintexEco APA - a precipitation inhibitor which prevents uneven dyeing caused by precipitation during dyeing;

Competitor Masterbatch (A) - refers to a competitor masterbatch sold for the same purpose as described herein.

Test 1 - Colour fastness

The test knitting socks(5 x 5 ± 0.2 cm) is attached to a piece of multi-fibre test fabrics (Testfabrics Inc, 54 mm filling bands) which is composed of acetate, cotton, polyamide, polyester, acrylic and wool. The test knitting socks which attached to a multi-fibre test fabrics is immersed in a boiled water for 5 minutes, and then rating the colour of the multi-fibre test fabrics by the Gray Scale to measure the grade of washing fastness after the test sample is dried.

1 - Preparation of masterbatch

Eastman AQ™ 55S was pre-dried at 50°C to 60°C in a dehumidifying dryer to a moisture content of less than 2000ppm. The dried pellets (50.0 wt%) were side fed to a hopper of an extruder and dry blended with milled Eastion PET CB-602 (50.0 wt%). The mixture was extruded at 280 °C to 260 C with 300rpm to produce pellets of masterbatch. fibre

The masterbatch of Example 1 (20 wt%) and PET CMFC (80 wt%) were mixed and melt- extruded through a 80cm extruder, L/D ratio 28/1 and a 72 hole (diameter 0.4mm) spin pack at 260 C to 290 C. The extruded fibre was drawn from the spinneret with 190-800 m/min. roller speed.

Fibre yarn was made to knitting socks by a cylinder knitting machine (Geeng Tyan Enterprise Co., Ltd, 200 needles) for dyeing. of blanks

A dye solution is formulated from the ingredients in the table below, with stirring over 24 hours at ambient temperature.

A tube filled with dye solution (40g) and knitting sample (2g) was heated at 2°C/minute to 80°C, then heated to 120 C at 5°C/minute, followed by being maintained at 120 C for 30 minutes for dyeing. The knitting sample is removed and washed with water after the tube has cooled to ambient temperature by natural cooling.

Example 5 (comparative example) - Preparation of blank from spun fibre incorporating Competitor Masterbatch (A)

Following the procedure described generally in Example 2, Competitor Masterbatch (A) (10 wt%) and the same PET as in Example 2 (90 wt%) were melt-extruded and processed to produce drawn fibre, as described in Example 2 from which a dyed blank was produced as described in Examples 3 and 4.

Example 6 - Comparison of dye blanks described in Examples 4 and 5

The blanks prepared as described in Examples 4 and 5 were subjected to Test 1 and the results showed that the colour depth of the two samples was similar. In addition, the wash colour fastness of the two samples in boiling water was similar.

Example 7 -Preparation and assessment of masterbatch made with rPET.

A masterbatch was prepared as described in Example 1 except that 50wt% of the PET used as the carrier resin was rPET and 50wt% was virgin PE. Dyed fibre was produced as described in Examples 2 to 4 mutatis mutandis. Analysis of the dyed samples showed that the tinting rate was similar for PET or rPET based masterbatches.

It will be appreciated from the above that the masterbatches prepared can produce excellent properties of dyed PET. In addition, there are a number of other advantages in using a masterbatch as described, including the following:

(i) As an alternative to use of virgin PET, rPET may be used to prepare a masterbatch as described in Example 1 . This would not readily be possible with Competitor Material (A) because that material is believed to prepare in a copolymerisation process and is therefore not relevant to rPET which by definition comprises pre-made PET.

(ii) Properties of the spun fibre can be manipulated by incorporating further ingredients in the masterbatch. For example, anti-oxidants (eg Irganox 1010, Irganox 1076, Irgafos 168, Revonox 608, DEOX 604), elastomers or chain extenders (eg Joncryl® ADR-4468, Joncryl® ADR- 4400, Trimethyl trimellitate) may be included in the masterbatch; or the possibility of selecting PET or rPET having a particular IV will allow tenacity of fibre produced to be readily adjusted.

(iii) The masterbatch may include toner to reduce yellowing which may occur during spinning processes using rPET.

(iv) Other functional additives (e.g. anti-bacterial agents, cooling agents, warming agents or anti-static agents) may be included in the masterbatch to enhance other properties.

Example 8 - Preparation of a dry blend for use in manufacture of spun fibre.

As an alternative to the masterbatch of example 1 , a dry blended composition may be prepared as follows:

(i) low melting PET and talc (15wt%), a nucleating agent, were extruded and pelletized.

(ii) 25 part by weight of the pellets produced in (i) were dry blended with 75 parts by weight of Eastman AQ™ 55S polymer.

(iii) The dry blend referred to in (ii) was used to produce fibres as described in example 2 mutadis mutandis.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.