WO2009076990A1

WO2009076990A1 - Process for the preparation of synthetic fibres for yarns with increased dyeability

Info

Publication number: WO2009076990A1
Application number: PCT/EP2007/063930
Authority: WO
Inventors: Gino Declercq; Jan Lams; Johan Lammens; Luc Callens; Luc Nelis; Luc Vlieghe
Original assignee: Balta Industries Nv
Priority date: 2007-12-14
Filing date: 2007-12-14
Publication date: 2009-06-25
Also published as: BE1018358A3

Abstract

This invention relates to a process for the preparation of polyolefin based synthetic fibres for yarns, in which a polymer mass is melted under pressure and then forced through a spinning block to form fibres, and in which the fibre bundle thus obtained is cooled, wherein prior to extrusion a mixture of PET (polyethylene terephthalate) or co - polyester and SEBS (styrene ethylene butylenes copolymer) is added to the molten polymer stream, so that the dyeability of the synthet ic fibres is improved. The invention also relates to the synthetic fibres for yarns, made in this way. This invention further relates to a rug or carpet comprising such a synthetic fibres.

Description

PROCESS FOR THE PREPARATION OF SYNTHETIC FIBRES FOR YARNS WITH INCREASED DYEABILITY

The present invention relates to a process for the preparation of synthetic fibres for yarns, in which a polymer mass is melted under pressure and then forced through a spinning block to form fibres, and in which the fibre bundle thus obtained is cooled. The invention also relates to the synthetic fibres for yarns, made in this way. This invention further relates to a rug or carpet comprising such a synthetic fibres.

Synthetic fibres are some of the starting materials used in the rug and carpet (textile floor coverings) industry, along with natural fibres such as cotton, wool and silk, for example. For making such fibres, synthetic starting materials are supplied in the form of granulates or particles, examples being polyamides (PAs), polyesters (PET or PESs), polypropylene (PP) and polyethylene (PE). These starting materials are converted into synthetic fibres by melting, and the semi- finished product thus obtained is used as the starting material for further processing in the textile industry.

Synthetic textile fibres can be either staple fibres or filaments, depending on their length: - staple fibres or simply "fibres" have a fairly short length of a tens or hundreds of millimetre, while - filaments have a continuous length of thousands of metres.

Fibres can be spun into yarns in spinning mills. Filaments, on the other hand, are taken together to form a bundle of fibres, or in particular a bundle filaments, at the bottom of a spinning shaft. The number of filaments involved here varies according to the quality and the application envisaged. Yarns are used to make woven fabrics, carpets, knitwear and clothes. Synthetic fibres are marketed in various forms, such as continuous fibres (CF), bulked continuous fibres (BCF), staple fibres, tapes and monofilaments, which have the following characteristics:

- continuous fibres are endless untextured yarns; - bulked continuous fibres are endless but textured or bulked yarns, which have been made fuller by texturing or bulking;

- staple fibres are filaments that have been cut into fibres for further processing and can be used either in spinning mills or for making non- woven materials; - tapes are made by cutting a film and are often used as a starting material in the production of packaging materials or for the backing and/or binding of carpets, and;

- monofilaments are threads consisting of only one fibre.

In the production of synthetic fibres for yarns for rugs and carpets, polypropylene homopolymer is often used and has economic and physical advantages, e.g. stain free and a low cost compared to other polymers. Polypropylenes are translucent white in their natural condition and can be coloured via different methods. In the production of synthetic fibres, the fibres are, coloured in the mass by, for example, adding a masterbatch containing organic and/or mineral pigments to the melt in order to obtain the desired colour of the final carpet fibre. Another method for colouring synthetic fibres is dyeing the fibres after spinning, however, in contrary with most other artificial fibres, polyolefins are not easily dyeable by the common dyes, known by those skilled in the art.

Dyes have been developed permitting direct dyeing of the polyolefin fibre with hydrocarbon soluble dyes with long alkyl-chains.

Since 1960, an important number of patents and publications describe the modification of the virgin polymer permitting the dyeing of the polyolefin after spinning: use of nickel compounding in the fibre and ligand- forming dyes, blends with polyamides and co-polyamides, polyesters and co-polyesters, blends with polyethylene alkylacrylates, blends with ethylene vinylacetates, blends with polystyrene and modified polystyrene, blends with hyperbranched polyesters, hyperbranched polyester-amides, in situ grafted unsatured amphiphiles, blends with nanoparticles.

Mostly blends are stabilised by the use of a compatibilizer, known by those skilled in the art, with or without reactive groups or grafts, are made in situ by maleic anhydride or maleated polypropylene, or a radical initiator during the blending step of the polymers.

US 4.764.551 describes a blend of a poly-alfa olefin and an ethylene dialkylaminalkylacrylamide copolymer, and an alkali metal salt of an organic carboxylic acid dyeable with acid dyes.

US 5.576.366 and WO 95/33882 describes a blend of polyolefϊn with ethylene alkylacrylate, a small amount of polyester and a hydrophilic modifier comprising of a monoglyceride and a salt of a linear alkyl. The blend is dyeable with disperse dyes. Sulfonic acid groups may be added to the polyester for cationic dyes.

US 5.468.259 describes the blend or graft of ethylene alkylacrylates onto polyolefin, in particular polypropylene.

US 6.127.480 describes a blend of polyolefin with the reaction of a functionalized polyolefin and polyetheramine. Disperse dyeable polyolefin fibres are disclosed.

US 6.555.038 describes a method for producing aqueous liquor dyeable modified polypropylene threads. A CR polypropylene is mixed with a reaction partner which can react with CR polypropylene. Suitable reaction partners are difunctional carboxylic acids or corresponding carboxylic acid derivatives. Acid dyes, dispersion dyes, reactive dyes as well as cationic dyes are used. US 6.312.631 describes a polyolefϊn composition having enhanced dyeing capability containing a polyolefϊn and a migratable amphiphile and 0.01 to 1000 ppm of a transition metal. Acid dyes, reactive dyes and basic dyes are used.

WO 97/47684 describes a blend of polypropylene, a co-polyamide and EVA. The blend is dyeable with disperse dyes.

US 4.520.155 discloses a polyolefϊn composition dyeable with acid dyes, basic dyes, disperse dyes, soluble vat dyes, azoic dyes and premetallized dyes.

US 6.646.026 discloses a new method of dyeing polymers by dispersing nano materials into the polymers to form polymer nanocomposites. The polymer nanocomposites obtained are dyeable using conventional methods.

US 6.444.758 describes the incorporation of amphiphilic blockcopolymers in order to increase the surface energy of polymeric substrates. A dyeable polypropylene fibre is disclosed. Disperse dyes and acid dyes are revealed as the colouring agents.

WO 2006/038061 describes the colouring process of polypropylene/polystyrene support in which the support is coloured by means of polypropylene/polystyrene support, especially fibres, by means of an aqueous composition comprising 0,1 to 4

% by weight disperse dye, organic acid with 1 to 6 carbon atoms, and at least a surfactant whereby said colouring is at least operated partly at a temperature higher than 90⁰C. the polystyrene/polypropylene weight ratio comprised between 1 :20 and 1 :4.

WO 03/029536 describes a blend of a polyolefm and a fibril forming polymer, whereby the exterior surface of the fibres is substantially devoid of fibrils. Between 5

- 45 % polyamides and polyesters are used as fibril forming polymers. Preferred polycondensation products are polyethylene terephtalate, polybuthylene terephtalate and polytrimethylene terephtalate. The blend may contain between 0 and 20% of an interphase modifier (compatibilizer) selected from several polyolefm polymers reacted with acids or anhydrides.

US 6.537.660 describes a fibre including 2% - 95 % block copolymer of at least one polymer block comprising 50 to 100 % by weight of olefinic monomers units and one polymer block comprising 0,1 to 100 % by weight of (meth)acrylic monomer units.

US 6.312.783 claims a fibre comprising 60-95% polypropylene, 0,1 - 10 % w/w maleated polypropylene and 5 - 40 weight% nylon or polyester.

US 6.869.679 describes the use of PET G in a blend with polypropylene and the use of maleic anhydride as a grafting agent. The application is demonstrated with examples in the apparel and home furnishing industry.

US 6.054.215 describes disperse dyeable polypropylene fibers manufactured by making polypropylene resin composition chips by dispersing 100 parts by weight polypropylene, 1 -10 parts by weight of semi-cristalline functional high polymer, 0.05 - 5 parts by weight of amorphous functional polymer and 0.1 - 3 parts by weight additives. The novel fibre has the aromatic, ester, ether and hydroxyl radical all together.

US 6.165.584 describes a resin comprising the reaction product of a polypropylene and the ethylene alkyl acrylate copolymer. The fibre comprises a polyester, a hydrophilic modifier or a polyamide.

Most of the above mentioned techniques may suffer from different problems such as for example problems during industrial spinning caused by the dye improving compounds hence limiting speed and increasing production cost, insufficient dye uptake for deep dyeing applications, insufficient rub resistance, degrading of resilience or reducing the "point" (filaments remaining together after twisting and heatsetting) of the carpet fibre, odour problems during spinning.

The aim of the present invention is to provide an alternative method for the preparation of synthetic fibres for yarns, in particular for use in carpet manufacturing, with enhanced dyeability. Further object of the invention is to obtain a synthetic fibre, which is easy to dye and with good properties.

The aim of the invention is achieved with a process for the preparation of polyolefm based synthetic fibres for yarns, in which a polymer mass is melted under pressure and then forced through a spinning block to form fibres, and in which the fibre bundle thus obtained is cooled, wherein prior to extrusion a mixture of PET (polyethylene terephthalate) or co-polyester and SEBS (styrene ethylene butylenes styrene-copolymer) is added to the molten polymer stream, so that the dyeability of the synthetic fibres is improved. Preferably, the polymer mass comprises from about 80 % to about 99 % w/w polypropylene homopolymer or polypropylene copolymer. The presence of PET or co-polyester and the SEBS copolymer permit the production of a fibre with a strongly increased dispersible dye uptake, a high rubbing fastness, good colour light fastness and good resilience for use in the carpet and rugs production. Further, due to the method according to this invention the yarn is very easy to produce and gives no odour problems during spinning.

In a preferred embodiment of the process according to the present invention the mixture comprises from about 1 to about 15 % w/w PET or co-polyester and from about 0 to about 5 % w/w SEBS. PET may be used in the blend, but most preferably an amorphous co -polyester polymer is used in order to decrease the processing temperature at the yarn extrusion step. Said amorphous co -polyester has in a preferred embodiment of the process according to the invention a glass transition temperature inferior to 100⁰C, and preferably around 80⁰C in order to obtain a fast dye uptake in standard atmospheric pressure procedures.

The SEBS may contain functional groups like e.g. sulfonic acid groups, or an epoxygroup, but preferably unmodified SEBS is used to improve the dispersion of the PET or co -polyester in the polyolefin matrix.

In a more preferred embodiment of the process according to the present invention the mixture comprises from about 0 to about 3 % w/w amphiphile. The amphiphile is added in order to control the melt viscosity of the co-polyester in the masterbatch and to improve its dispersion in the polyolefin matrix. Said amphiphile is preferably a metal alkylbenzenesulfonate and has preferably a low molecular weight, most preferred are sodium stearate and his fatty acid homologues and sodium dodecylbenzene sulfonate and its alkylbenzene sulfonate homologues. The presence of the amphiphile improves the dispersion of the co-polyester during extrusion and the dye uptake during the dye process.

In a particularly preferred embodiment of the process according to the present invention, said process further comprising heatsetting the obtained fibre bundle at a temperature in the range of 130 ⁰C to 150 ⁰C. After heatsetting the fibre demonstrates an improved elastic behaviour.

In a most preferred embodiment of the process according to the invention the said process further comprises dyeing the fibre bundle with a disperse dye to provide dyed fibres.

Another aspect of the present invention relates to polyolefin based synthetic fibres for yarns wherein a process as described above preferably produces the synthetic fibres in question The obtained fibre is preferably absolutely colourless before dyeing and insensitive towards yellowing, typical for some polyamide containing polyolefϊn blends. The mechanical properties of the obtained fibre allow twisting, cabling, heatsetting, weaving or tufting, knitting and all other textile operations without creating supplementary problems.

In particular the fibre according to the invention can be used for the manufacturing of interior textile, rugs, carpets and upholstery.

A further aspect of this invention relates to a rug or carpet, wherein said rug or carpet comprises polyolefϊn based synthetic fibres as described above.

The following more detailed description of the process according to the invention is given to illustrate the features, advantages and special characteristics of the invention in more detail. However, it will be obvious that the scope of protection sought in the claims in respect of the process and the synthetic fibres according to the invention is not restricted by anything stated in the following description.

To produce synthetic fibres for yarns, in particular yarns for rugs or carpets, by the process according to the invention, a polymer mass is first melted under pressure and then forced through a spinning block to form fibres, after which the resulting bundle of fibres is cooled. A continuous process produces the synthetic fibres. The individual filaments may be of any cross-sectional shape, including trilobal, round, multilobal, deltashape, hollow, core - shell, etc... . The carpet yarns are between 600 and 6000 dtex and are composed of 50 to 420 filaments. These values are only given as an example, and are no limits.

A synthetic starting material, preferably polypropylene homopolymer or polypropylene copolymer for example, polypropylene containing a variable amount of ethylene, or other alfa olefin, supplied in granulate or particulate form, is melted under pressure in a melting device, which may be an extruder, for example. In order to improve the dyebility of the produced fibres, a mixture of a PET or co - polyester and SEBS is added to the molten polymer stream. Said mixture may be added directly on a BCF carpet yarn extrusion line, or preferably a masterbatch may be prepared in order to add the mixture and eventually other additives to the polypropylene before extrusion. A compound containing all the fibre constituents may also be prepared.

The SEBS copolymer may contain reactive groups, for example sulfonic acid or carboxylic acid or carboxylic acid salt groups, and most preferably epoxy groups, but unmodified SEBS performs very well.

The presence of PET or co - polyester and the SEBS copolymer permit the production of a fibre with a strongly increased dispersible dye uptake, a high rubbing fastness, good colour light fastness and good resilience for use in the carpet and rugs production. After heatsetting between 130 ⁰C and 150 ⁰C, the obtained fibre demonstrates an elastic behaviour which may increase the comfort of the user.

The obtained fibre is further processed in order to make space dyed yarn and printed and dyed carpets with disperse dyes. Following processes are given as an illustration but are not limiting the scope of this invention and other applications in apparel and upholstery are possible.

PET may be used in the blend, but most preferably an amorphous co-polyester polymer is used in order to decrease the processing temperature at the yarn extrusion step. Sufficient (co-)polyester fibrils should be at the fibre surface in order to facilitate the colour uptake. Amphiphiles may be present to increase the wet-ability of the fibre (anti static and dyeability improvement) and permit to control the rheology of the co-polyester because they act as a plasticizer or even by degrading the polyester polymer chain during the melt phase. The amorphous co -polyester is composed of terepthalic acid and may contain isopthalic acid and other aromatic dicarboxylic acids (example 2,6-napthalene dicarboxylic acid) or aliphatic dicarboxylic acid (1,4 -cyclohexane -dicarboxylic acid) and as a diol may contain ethylene glycol, 1,4 -cyclohexane dimethanol, 2,2- dimethylpropane- 1 ,3 -diol, propylene glycol, butylene glycol, 1 ,2 -butanediol, 1,3 - butanediol, 1,4 -butanediol, 1,2 -pentanediol, 1,4 -pentanediol, 1,5 -pentanediol, 1,6 -hexanediol, 2,2,4 -trimethyl-1,3 -pentanediol and mixtures thereof. The co- polyester may also contain low amounts of a trifunctional monomer as described in US patent 4,983,711.

The used amorphous co-polyester has a sufficient low shear viscosity at 250 ⁰C, this will permit a good blending in industrial single screw extruders used in BCF carpet yarn production lines. The melt viscosity is determined with the standard MFI test, but at extrusion temperature (250 ⁰C) and 2,16 kg pressure.

Values for the basic polymers, without plasticizers or melt flow modifiers are: polypropylene 33,4 co -polyester EB022 19,1 co -polyester EB062 14,2

The glass transition temperature (Tg) should preferably be inferior to 100 ⁰C, and most preferably around 80 ⁰C, in order to obtain a fast dye uptake in standard atmospheric pressure procedures. The hardness of the polyester copolymer should be as high as possible, since a number of the co-polyester micelles of the PP/co- polyester/SEBS blend are at the surface of the fibre, permitting very fast colour uptake during dyeing, but could render the fibre fragile against rubbing in dry or humid test conditions.

Excellent rubbing test are obtained with deep dyed fibres. In our examples, we use two commercial types produced by Eastman which are very satisfactory having recommended extrusion temperatures in the range of 220 ⁰C - 245 ⁰C, which are attainable on the classical polypropylene yarn extrusion and are the preferred extrusion temperatures for BCF carpet yarns, as known by those skilled in the art. The amorphous co -polyester used in the examples are: Eastar co-polyester EB062 and Eastar copolyester EB022.

As a compatibilizer and a fibre modifier, a SEBS copolymer is used in the blend. This SEBS copolymer has a preferred styrene content from 10 to 35 % Styrene. The following products are used in the examples tested: ASAHI KASEI CORPORATION, tuftec H 1062 (medium Styrene), tuftec H 1221 (low Styrene), and POLIMERI EUROPA Europrene SOL TH 2311 (high Styrene).

SEBS, co-polyester and polyolefin should be selected in order to obtain a very fine dispersion of the micelles in the polyolefin matrix. Known by those skilled in the art, the shear viscosity of all constituents of the blend should be as close as possible at the processing temperature. The use of a static mixer to improve further the dispersion of the blend, installed between the extruder and the spinnerets, could further enhance the process.

Other common constituents may be added to the blend, like for example, without limitation, slipagents, pigments, TiO₂ as an anti lustre agent, flame retardant agents, anti oxidants, UV protection agents, other polymers like EVA, EMA, EEA, mineral particles like calcium carbonate or talc, chemical blowing agents, etc...

In a preferred embodiment, a part of the polyester or co -polyester may be replaced by a medium molecular weight polystyrene. Since SEBS is used as a compatibilizer, polystyrene is very well dispersed in the fibre and will enhance the dyeability. The polystyrene will not degrade the rubbing fastness of the fibre. The amount of polystyrene is preferably between 0 % and 5% and most preferably between 0 % and 2 %. All polypropylene in the test was standard grade fibre forming polypropylene from Basell (Basell Moplen HP552R with a MFI of 25 at standard conditions). The presence of 0 - 3% of a low molecular weight amphiphile, most preferred are sodium stearate and its homologues, and sodium dodecylbenzene sulfonate and its homologues improve the dispersion of the co -polyester during extrusion and the dye uptake during the dye process. It is known that meltblending of an aromatic polyester and a metal alkylbenzene sulfonate may degrade the polyester.

Not be bounded by any theory, the decomposition of polyesters by metal dodecylbenzene sulfonate is described as a not wanted phenomenon in US 5,045,580. However, this degradation of the polyester reduces the molecular weight and hence reduces the melt viscosity and improves the dispersion of the polyester in the polyolefm matrix. An other amphiphile acting as a plasticizer for the (co- )polyester and improving dispersion of the (co-)polyester in the polyolefm matrix is N ',N' - ethylene - bis - stearamide known as a plasticizer for polyester by lowering the Tg of the blend (US patent 4,894,404). Fatty acid esters from alkyl alcohols or from polyols (ex. polyglycol stearates) could be added and could under certain conditions react by transesterification in the extruder during the production of the masterbatch containing the (co-)polyester and the other additives. This masterbatch will be used in the final processing with the polyolefm during the yarn extrusion step.

A blend of Eastman co-polyester Eastar EB022 with 5 % N₅N' - ethylene -bis- stearamide has a MFI at 250 ⁰C and 2,16 kg of 24,4. No degradation of the polyester has been detected. Preferably a masterbatch containing the co-polyester, the SEBS copolymer, eventually some polyolefm and the metal alkylbenzene sulfonate is preferred to obtain a homogeneous polymer blend with fine micelles of the co- polyester in the polyolefm matrix. Sodium dodecylbenzene sulfonate is known in itself as a dye enhancing compound in polyolefϊns (WO 1985/004889).

Following polypropylene blends containing 7 % co-polyester, 3 % SEBS and 0,1 % wt, 0,3 % wt, 0,6 % wt and 1 % sodium dodecylbenzene sulfonate have been extruded and 138 filament 2000 dtex yarns has been produced. After tufting, the yarns are dyed with disperse dyes under standard conditions and the colour intensity is appreciated. Increasing amounts of sodium dodecylbenzene sulfonate improve strongly the dye uptake of the fiber, even at these low concentrations.

The blends of sodium dodecylbenzene sulfonate and a co-polyester (Eastar EB022) permit to control the rheology of the co -polyester containing masterbatch. Measurements at 230 ⁰C and at 250 ⁰C reveal a decreasing viscosity. The two components are blended in a double screw blender at 250 ⁰C, and the MFI is determined at two temperatures:

Example 1 of the fibre manufacturing

In a Rieter industrial BCF yarn extrusion unit, at a temperature of 250 ⁰C, 90 % polypropylene with a MFI of 25 is blended with 10 % w/w of a masterbatch, composed of 70 % co-polyester (Eastman Eastar EB062) and 30 % SEBS (Europrene SOL TH 2311). An equivalent of 0,1% TiO₂ is added through the way of a second TiO₂ containing masterbatch. Extrusion parameters are the usual one known by those skilled in the art. Extruder temperature was 250 ⁰C. The winder speed after the cooling drum was 2200 meter per minute. The yarn was a 1250 dtex, 69 filament, trilobal type. A spinoil with sufficient hydrophilic properties should be selected (emulsion type), since the surface properties of the filaments are clearly modified compared to a mass dyed polypropylene fibre. This yarn has been cabled at 210 twist/meter and has been heatset on a Superba machine with saturated steam at 134 ⁰C for one minute. A frise effect is obtained by use of a stuffer box with steam injection.

The dyeability of the yarn has been evaluated in different ways. Colour uptake Yield has been determined by light reflection measurements of the fibres and by spectrophotometric measurements of the dyebath before and after dyeing. In all cases colour yields are superior to 85 %.

Example 2

In a Rieter industrial BCF yarn extrusion unit, at a temperature of 250 ⁰C, 90 % polypropylene with a MFI of 25 is blended with 10 % of a masterbatch, composed of 50 % co-polyester (Eastman Eastar EB022), 20 % polystyrene (Polimeri Europa, medium molecular weight PS (Mn: ± 62 000; Mw: ± 118 000; Mz: ± 190 000) and a MFR at 200 ⁰C - 5 kg. (ISOl 133) of 25) and 30 % SEBS (Marubeni, Tuftec H1062). Extrusion parameters are the ones mentioned in example 1. The yarn is a 2150 dtex 96 trilobal filament yarn and is used as such in further trials.

Example 3

A masterbatch containing 7 parts of amorphous co-polyester (Eastman Eastar EB022), 3 parts of SEBS and 1 part of sodium dodecyl benzene sulfonate is prepared in a double screw extruder Leistrits (27 mm, 32 L/D) at a temperature of 220 ⁰C. The masterbatch components are blended with polypropylene at a ratio 11 % masterbatch and 89 % polypropylene and extruded on an industrial BCF carpet yarn Rieter production line at 250 ⁰C extruder temperature at a yarn winder speed of 2200 m/minute. The obtained yarns can be used with and without heatsetting, but some properties are only revealed after heatsetting. We found that after heatsetting the fibre becomes more elastic than the non-heatset fibre. Dye uptake was excellent after heatsetting, most preferably after heatsetting with saturated steam. Also, the behaviour of the yarn according to this invention allowed further processing at speeds that are known and normal for unmodified polypropylene yarns.

Above mentioned yarns are further processed as described in following known processes by those skilled in the art of polyamide dyeing.

The synthetic fibres for yarns according to this invention have an enhanced dyeability. Following is an example (in different stages) of a colouring method of the synthetic fibres produced by the process according to this invention.

Stage 1

Fibres made according a process as described above - in a dtex that may vary between 1200 and 4500 - were knitted into socks on e.g. 1/5" gauge circular knitting machines containing 186 needles each and making between 180 and 270 rpm. The socks were rolled on a cone to form rolls of between 30 and 50 kg.

Stage 2

Following dyeing bath was prepared for the padder:

A tank containing water at room temperature was agitated. Hereto 1 to 10 g/1 of an anionic or non-ionic surfactant was added, together with an acid in an amount as to achieve a pH of between 4 and 6. Also 10 to 15 g/1 of a printing thickener was added, before adding the necessary amount of separately in hot water diluted disperse dyes, in this case between 0,1 and 1 g/1. The disperse dyes in this case being of a type like e.g. Huntsman's Terasil C. For the print rollers which are carved with a design, the dye bath was as described for the padder, except for the amount of printing thickener which was much higher, i.e. between 30 and 50 g/1. Also much more - 2 to 15 g/1 - of separately diluted disperse dyes of the same type were added.

All tanks were then stirred for at least 30 minutes before using.

Stage 3

The rolls of socks described in stage 1 were put on the rack of a space dyeing machine - 3 or 4 next to each other, according to their width - and melt or sewed to a leader fabric and later to the next roll, thus allowing a continuous process of dyeing, steaming, rinsing, lubricating, drying and winding back onto rolls.

When the machine was started, the socks were gradually wound off and first led in the dyebath of the padder (in this case a horizontal Kϋsters type), after which they were squeezed between its rollers in order to obtain a dye-bath pick-up of between 70 and 120% on the weight of the socks. Thus a ground-shade was provided to the socks. Pre -washing (cold or warm) is optional, but was not used in this case. The speed of the machine may vary between 15 and 40 meters per minute. The socks were then led between up to 4 pairs of printing-rollers, in this case placed vertically above each other and engraved with a design. Each pair of rollers contains a part of the design and puts on a specific colour.

The socks were subsequently led into a steamer at atmospheric pressure at a temperature of between 95 and 105⁰C, this during a period of 4 to 7 minutes.

In a next step of the continuous colouring process, the socks were washed and squeezed in up to 4 cold or warm water rinsing baths and were then led through a bath containing a lubricating product and squeezed again before drying during 30 to 90 seconds at 105 to 130⁰C, preferably 110⁰C. The coloured socks were finally rewound onto cones forming rolls again.

Stage 4 The threads of the coloured socks on rolls were then rewound onto cones, a process which occurs at a speed of between 500 and 1100 m/min. this process is facilitated by the lubricating agent added in the previous stage.

Stage 5 The thus obtained coloured threads or yarns were then - partly through an intermediate operation, such as air-entangling or cabling and heat-setting - used as pile material for tufted or woven carpets. They may in the intermediate operation be mixed with other types of yarns, such as e.g. nylon or standard solution dyed polypropylene.

Stage 6

Carpets thus made have been proven to posses good colour-fastnesses. The score for light-fastness was at least 5/6, mostly better. Rubbing fastnesses dry and wet were awarded between 4 and 4/5-5. The said carpets also proved to be bleach-resistant, in a way equal to standard solution dyed polypropylene.

Brief description of other examples of colouring applications

Ex. 1:

If yarns according to this invention - dyed and printed in the above described way - are combined with ecru PA yarns through air-entangling or cabling and heat-setting and made into carpets by tufting or weaving to be dyed a second time with conventional acid or metal complex dyes such as Tectilon or Lanacrone (by Huntsman), they do not take up the colorants of the second dyebath, i.e they are overdyeable with such colorants and retain their original colour. The ecru PA yarns of course are coloured by this second dyeing operation.

Ex. 2: If yarns according to this invention in ecru condition are combined with ecru PA and made into a carpet, they can be dyed with a bath containing both acid (or metal complex) dyestuffs and disperse dyestuffs, resulting in a two colour effect. This phenomenon can be called differential dyeing and is explained by the fact that the yarn according to this invention only takes up disperse dyestuffs, whereas PA takes up both disperse and acid/metal complex dyestuffs, resulting in two different colours.

Ex. 3:

Ecru carpets made of yarns according to this invention can be printed with a light and bright colourdots and subsequently overdyed with a dark flood. Both print - and dyebaths contain disperse dyestuffs. This mechanical resist printing is strong enough to prevent serious contamination of the printed colours by the dark flood without the help of a chemical additive traditionally needed for this method of printing on PA carpets or yarns.

Claims

1. Process for the preparation of polyolefm based synthetic fibres for yarns, in which a polymer mass is melted under pressure and then forced through a spinning block to form fibres, and in which the fibre bundle thus obtained is cooled, characterized in that prior to extrusion a mixture of PET or co -polyester and SEBS is added to the molten polymer stream, so that the dyeability of the synthetic fibres is improved.

2. Process according to claim 1, characterized in that the mixture comprises from about 1 to about 15 % w/w PET or co -polyester and from about 0 to about 5 % w/w SEBS.

3. Process according to claim 1 or 2, characterized in that the polymer mass comprises from about 80 to about 99 % w/w polypropylene homopolymer or polypropylene copolymer.

4. Process according to any one of the preceding claims, characterized in that said co -polyester is an amorphous co -polyester.

5. Process according to any one of the preceding claims, characterized in that the mixture comprises from about 0 to about 3 % w/w amphiphile.

6. Process according to claim 5, characterized in that said amphiphile is a metal alkylbenzenesulfonate.

7. Process according to claim 5 or 6, characterized in that said amphiphile is sodium dodecylbenzene sulfonate.

8. Process according to any one of the preceding claims, characterized in that said process further comprising heatsetting the obtained fibre bundle at a temperature in the range of 130 ⁰C to 150 ⁰C.

9. Process according to any one of the preceding claims, characterized in that said process further comprising dyeing the fibre bundle with a dispersed dye to provide dyed fibres.

10. Polyolefm based synthetic fibres for yarns, characterized in that the said synthetic fibres are made by a process specified in any one of Claims 1 to 9.

11. Rug or carpet, characterized in that said rug or carpet comprises polyolefm based synthetic fibres according to claim 10.