EP3914438B1

EP3914438B1 - Method for dyeing a textile article made of modified polyester

Info

Publication number: EP3914438B1
Application number: EP20700933.3A
Authority: EP
Inventors: Nerino Grassi; Mauro ZALTIERI
Original assignee: Golden Lady Co SpA
Current assignee: Golden Lady Co SpA
Priority date: 2019-01-23
Filing date: 2020-01-22
Publication date: 2022-11-02
Anticipated expiration: 2040-01-22
Also published as: WO2020152225A1; ES2937975T3; PL3914438T3; EP3914438A1

Description

TECHNICAL FIELD

The present invention relates to the field of polymers. In particular, aspects disclosed herein relate to improvements to methods for producing or processing polymers for producing synthetic threads, fibers and yarns, for example for producing woven, nonwoven or other textile articles. Specifically, some aspects of the present invention relate to improvements to methods for dyeing polymer textile threads or yarns, or other textile articles, in particular based on polyesters and specifically on polyethylene terephthalate (hereinafter also PET).

STATE OF THE ART

In the production of textile articles, for example for the clothing, furnishing, automotive and other fields, processes for dyeing thread after extrusion thereof are known. To this end, the thread is wound around dyeing tubes to form reels or bobbins of thread, which are then stacked one on top of the other in a container of a dyeing machine. The container is closed and a dye bath is circulated therein. In some cases, garment yarn dyeing takes place, i.e. after the thread or yarn has been transformed into a finished or semi-finished product or textile article. In this case the textile article is first produced in the form of a garment, piece or other semi-finished article. The garment is then inserted into the dyeing machine.
Usually, the dye bath has high temperatures, higher than the boiling temperature at ambient pressure. Therefore, to reach the temperature required for dyeing, pressurized machines are necessary. Typically, dyeing of PET-based yarns takes place at temperatures that, in some steps of the cycle, are around 130°.
The high temperature and pressure conditions are maintained for considerable long time, for example for a few hours.
It is understood that the dyeing process is a particularly energy-intensive process.
In order to obtain some advantages, including the possibility of dyeing at lower temperatures, typically below 100°C, and hence at ambient pressure, cationic polyesters that require maximum temperatures of the dyeing cycle in the order of 98°C have been developed. However, these modified polymers require dyeing times that are around twice those required to dye unmodified PET. This has a negative impact on energy consumption, as the lower temperature required must nonetheless be maintained for longer times.
It is also necessary to use a carrier to accelerate the dyeing process, in combination with the dye. The amount of dye required is considerably higher than the amount required to dye standard PET. All this has a negative impact on the cost of the consumable materials and an environmental impact that is not negligible.
Moreover, cationic PET has costs around 25-35% higher than a standard PET. This nullifies or at least reduces the economic benefit of energy saving in the dyeing step.
The textile product obtained from dyeing cationic PET has poor dyeing quality. The dye is not well fixed to the fiber.
WO01/34693 and WO2018/154403 disclose the use of modified PET for the production of a textile article. Beyene Duecha: "Anionic dyeability of polyester fabric by chemical surface modification", 30 September 2017, XP055620214 and Mazeyar Parvinzadeh et al "Surface and bulk modification of synthetic textiles to improve dyeability", in Textile Dyeing, 14 December 2011, XP055620217, ISBN: 978-953-30-7565-5: DOI: 10.5772/18706 concern polymers with improved dyeability properties.
Therefore, there is a continuous need to reduce the production costs and energy consumptions involved in dyeing threads for textile use, in particular polymer threads, obtaining high quality products.

SUMMARY

It has surprisingly been discovered that a PET with a polyethylene terephthalate chain that has been modified with the introduction of at least a polyether amine can be dyed at low temperatures, which can be reached at ambient pressure, in times comparable with those required for pressurized dyeing of standard (unmodified) PET. The cost of a PET modified with polyether amine can in some cases be comprised between the cost of the standard PET and the cost of more expensive cationic PETs, with consequent reduction of the cost of the finished product.
The terpolymer comprising the monomers forming the PET in combination with polyether amine can be obtained with a polymerization process starting from the three components of which it is formed. In this case the polyether amine-functionalized PET can be made available in granules or chips. The terpolymer is melted and extruded to produce thread. In other embodiments, the terpolymer, i.e., the polyether amine-functionalized PET, is obtained from PET previously produced through a polymerization process, proceeding by melting the PET in the presence of polyether amine. The procedure can be a reactive extrusion procedure, where a standard PET is brought into contact with polyether amine at high temperature and pressure and the molten mass comprising both the constituents is extruded to obtain the thread or yarn.
Therefore, according to one aspect, the present invention relates to a method for dyeing a textile article made at least partly of a polymer fiber or polymer yarn, according to claim 1. Further features of advantageous embodiments of the method according to the invention are set forth in the dependent claims.
In the present context, textile article is intended generically as a semi-finished or finished article, in thread or in garment form. For example, the textile article can be a thread or yarn, a wick, a garment, a piece of woven or nonwoven fabric, intended for subsequent converting operations, such as cutting and sewing.
According to yet another aspect, the invention relates to a method for dyeing a textile article made at least partly of polymer fiber or polymer yarn, comprising the steps of:

introducing a textile article comprising a polyethylene terephthalate and a polyether amine, for example in the form of fibers and/or threads or yarns, into a dye bath;
dyeing the textile article at a dyeing bath temperature no greater than 100°C and preferably greater than 70°C, preferably greater than 80°C, more preferably comprised, for example, between around 90 and around 99°C, so as to be able to carry out said dyeing step at ambient pressure.

The textile article can be a package of thread or yarn, for example a reel or a bobbin. In other embodiments, the textile article or product can be a knitted or woven textile article, or a nonwoven textile article, or any other textile article utilizing fibers, threads or yarns made of the aforesaid polymer comprising PET functionalized with polyether amine. The article can be a finished garment and therefore not intended to undergo further operations of cutting, sewing or the like. In other embodiments, the textile article can be a semi-finished article intended to undergo further conversions of form, such as cutting and/or assembly with other components to obtain the finished product. The textile article can therefore also be a piece of woven or nonwoven fabric.
The term thread or yarn as used herein can indicate in particular a substantially one-dimensional article, which can be formed by spun fibers or by single or multiple continuous filaments. A thread or a yarn can thus consist of discontinuous fibers (for example staple fibers) spun to form a substantially continuous article, or of one or more continuous filaments, obtained by extrusion of a polymer mass, for example by means of an extruder or a drawing machine.
The use of polyether amines as molecules for the functionalization of polymers is known. WO2014/057364 and WO2015/001515 disclose methods for producing modified polyamides, comprising nylon and a polyether diamine, to increase moisture regain, i.e. the capacity to absorb and retain moisture. In particular, these modified polyamides are suggested to improve the hand of fabrics and garments obtained therewith. However, these documents relate to a different family of polymers and suggest the use of polyether amines for different purposes. WO2018154403 discloses PET functionalized with polyether amines to obtain biocidal properties. In this publication, however, no particular properties concerning the dyeability of yarns obtained with this modified PET are disclosed.
The introduction of at least a polyether amine in the chain based on polyethylene terephthalate improves the dyeability properties simplifying the dyeing cycle, reducing its costs in terms of energy consumption and making it possible to operate in less onerous conditions.
Preferably, the polyether amine is mainly positioned as chain terminal in the polyethylene terephthalate, with a free amino terminal (NH₂).
The polyether amine can be a polyether monoamine.
In currently preferred embodiments, the polyether amine comprises more than one amino group and can therefore for example be a polyether diamine or a polyether triamine.
The polyether amine can be present in a percentage by weight equal to at least about 1%, preferably equal to at least about 2%, more preferably equal to at least about 5%, with respect to the total weight of the polyester. In embodiments described herein the polyether amine can be present in an amount by weight no greater than about 50%, preferably no greater than about 30%, more preferably no greater than about 25%, even more preferably no greater than about 20%, with respect to the total weight of the polyester. For example, the percentage by weight of polyether amine in the polyester can be comprised between about 1% and about 50%, preferably between about 1% and about 25%. In some embodiments the polyester comprises a percentage of polyether amine comprised between about 1% and about 20%, for example between about 2% and about 20%, or between about 2.5% and about 15%.
In some embodiments, the polyester can comprise a percentage of polyethylene terephthalate of at least about 50% by weight, preferably at least about 60% by weight, more preferably at least about 70% by weight, even more preferably at least about 80% by weight, with respect to the total weight of the polyester. In embodiments described herein, the percentage by weight of polyethylene terephthalate is no greater than about 99%, preferably no greater than about 98% by weight, even more preferably no greater than about 95% by weight, with respect to the total weight of the polyester. For example, the polyester can comprise from about 50% to about 99% by weight, preferably between about 75% and about 99% by weight, for example between about 80% and about 99% by weight, or between about 80% and about 98%, or between about 85% and about 97.5% by weight of polyethylene terephthalate.
In some embodiments, the polyether amine has a weighted average molecular weight (Mw) equal to at least about 500, preferably equal to at least about 800, more preferably equal to at least about 1000, even more preferably equal to at least about 1500, and preferably no greater than about 5000, more preferably no greater than about 3000, for example comprised between 1500 and 2800.
The thread or yarn made of PET modified and dyed according to the methods described herein can comprise only polyester containing polyethylene terephthalate and at least a polyether amine, as described above, but in some embodiments, the thread or yarn can contain one or more further components in addition to the modified polyester containing PET and polyether amine. In exemplary embodiments, different polymers can be combined with the polyester containing PET and polyether amine. For example, embodiments can have bi-component threads or fibers, where one of the components consists of polyester containing PET and polyether amine, and the other component can consist of a different polymer, for example a polyamide, or polyethylene terephthalate without polyether amine.
The bi-component fibers or filaments can, for example, comprise a percentage by weight of polyester, containing polyethylene terephthalate and polyether amine, in a percentage equal to at least about 40% by weight, preferably equal to at least about 50% by weight, even more preferably equal to at least about 60% by weight with respect to the total weight of the textile product.
Threads, filaments, fibers or yarns produced with modified polyester, containing polyethylene terephthalate and polyether amine as described herein, can be used as is or in a blend with other natural, artificial or synthetic threads, filaments, fibers or yarns, for example produced with other polymers such as polyester without polyether amine, or polyamide or other suitable components. In this case, in the textile product the polyester containing polyethylene terephthalate and polyether amine can be present in a percentage by weight equal to at least about 10%, preferably equal to at least about 50%, more preferably equal to at least 60% or 70%. Preferably, this percentage is no greater than about 95%, more preferably no greater than about 80% of the total weight of the textile product.
According to a further aspect, disclosed herein is a use of a polyester containing polyethylene terephthalate and at least a polyether amine, for producing a product or article with easy dyeability properties at ambient pressure.
According to a further aspect, disclosed herein is a method for conferring improved dyeability properties on a polyester containing polyethylene terephthalate, the method comprising the step of introducing a polyether amine into the chain of the polyethylene terephthalate, for example in a polymerization process, or subsequently to a polymerization process, causing previously polymerized polyester and polyether amine to react.
According to yet a further aspect, there is described a method for producing a polyester, in particular a modified polyester with improved dyeability properties, comprising reacting terephthalic acid, ethylene glycol and a polyether amine at temperatures and pressures sufficient to cause polymerization and formation of polyester containing polyethylene terephthalate and polyether amine.
In some embodiments, the method comprises the steps of:

reacting terephthalic acid and ethylene glycol with excess of ethylene glycol to obtain polyethylene terephthalate with terminal carboxyl groups;
reacting the terminal carboxyl groups with polyether amine and obtaining polyester containing a chain of polyethylene terephthalate and polyether amine.

According to other embodiments, the method provides for modifying a previously polymerized polyester, in order to introduce at least a polyether amine into the polyethylene terephthalate chain. The method can comprise the step of reacting polyethylene terephthalate with a polyether amine and obtaining a polyester having improved dyeability properties and containing polyethylene terephthalate and polyether amine. The method can, for example, be implemented in an extruder for producing a continuous monofilament or multifilament thread, made of polyethylene terephthalate modified with polyether amine, having improved dyeability properties, starting from polyester containing polyethylene terephthalate for example in the form of chips, granules or the like, to which there is added, directly in the extruder or in a container separated from the extruder and for example in fluid connection therewith, a suitable amount of at least a polyether amine. The polyester reacts with the polyether amine and the polyester thus modified is extruded to form a semi-finished article, for example a thread, for textile applications or the like.
To facilitate the reaction between previously polymerized polyethylene terephthalate and polyether amine, in some embodiments the method can comprise the step of adding a grafter or a chain extender. The method can comprise the steps of reacting the grafter or the chain extender with the polyethylene terephthalate for obtaining a functionalized polyethylene terephthalate; and of reacting the polyethylene terephthalate functionalized with polyether amine.
According to a further aspect, the invention relates to the use of a polyester fiber or thread, containing polyethylene terephthalate and at least a polyether amine, for producing a yarn or thread subjected to dyeing at ambient pressure.
In some embodiments, the polyether amine has at least two amino groups (NH₂), one of which is used to react with the polyethylene terephthalate and form a covalent bond with the chain of the polyester, and the other remains available in the resulting polymer chain.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to a series of exemplary embodiments and of results achievable therewith, illustrated in the accompanying drawings, wherein:

Fig. 1 shows a dyeing cycle with a standard PET in a first embodiment;
Fig.2 shows a dyeing cycle with a cationic PET in a first embodiment;
Fig.3 shows a dyeing cycle with a PET functionalized with polyether amine according to the present description in a first embodiment;
Fig. 4 shows a dyeing cycle with a standard PET in a second embodiment;
Fig.5 shows a dyeing cycle with a cationic PET in a second embodiment; and
Fig.6 shows a dyeing cycle with a PET functionalized with polyether amine according to the present description in a second embodiment.

DETAILED DESCRIPTION

In the following detailed description of examples of embodiments, the reference to "an embodiment" or "the embodiment" or "some embodiments" means that a particular feature, structure or element described in relation to an embodiment is included in at least one embodiment of the object described. Therefore, the phrase "in an embodiment" or "in the embodiment" or "in some embodiments" at various points of the description does not necessarily refer to the same embodiment(s). Furthermore, the particular features, structures or elements may be combined in any appropriate manner in one or more embodiments.
Ratios, concentrations, amounts and other numerical data illustrated and mentioned in the present description and in the appended claims can be expressed in the form of ranges. It must be understood that this form of expression is used for convenience and brevity. It must not be understood in the sense that a range comprises only the numerical data explicitly indicated as limits of the range. Instead, a range of values must be understood as extensive and flexible, in the sense of comprising all the numerical values individually contained in the range, and all the sub-ranges, delimited by any two numerical values contained in the range. Therefore, in general, the expression "a range from about A to about B" discloses not only the range defined by the ends A and B, but also any sub-range from "about X to about Y", where X and Y are values contained between A and B.
When a content of a substance A in a set B of substances is defined with a series of percentages of maximum values and a series of percentages of minimum values, it must be understood that the substance A can be contained in the set B with amount within a plurality of ranges each defined by a pair of any one of the minimum values and any one of the maximum values. For example, the definition "containing at least x%, preferably at least (x-n)%, and no more than y%, preferably no more than (y-m)%", comprises the ranges [x; y], [x; (y-m)], [(x-n); y], [(x-n); (y-m)]. Each of these ranges also comprises each sub-range defined between its maximum and minimum limits.
The term "about" can comprise rounding off to significant figures of numerical values.
The term "about" as used herein when referring to a numerical value or range of numerical values allows a degree of variability of the numerical value or of the range for example within 10%, or within 5% of the numerical value indicated or of the limit indicated of a range.
According to embodiments described herein, to obtain a polyester based polymer, containing polyethylene terephthalate (PET) having an improved dyeability, a polyether amine bonded to one or more monomers of polyethylene terephthalate in the polyester chain are used.
The polyester containing polyethylene terephthalate and polyether amine can be obtained starting from monomers (terephthalic acid and ethylene glycol) for producing polyethylene terephthalate, with batch or continuous polymerization reaction, during which at least a polyether amine is added.
Examples of polyether amines, and in particular of polyether diamines and polyether triamines that can be used in the methods and in the products described herein will be indicated below.
In some embodiments, the method provides for reacting terephthalic acid and ethylene glycol with an excess of ethylene glycol to obtain polyethylene terephthalate with terminal carboxyl groups, according to the reaction:
The reaction is conducted at pressures comprised between about 150°C and about 200°C and at pressure of about 4 bar with acid catalyst. The PET thus obtained is reacted with a polyether diamine obtaining modified polyethylene terephthalate with terminal groups NH₂, according to the reaction
where H₂N-R-NH₂ is a generic polyether diamine, examples of which are given later on in the present description. The reaction can take place at temperatures comprised between about 120°C and about 140°C for 24 hours at atmospheric pressure.
The modified polyethylene terephthalate thus obtained can be in granules, chips or other suitable form and can be used in subsequent production processes, for example for molding, injection, co-molding, extrusion, blowing, etc.
In particular, the polyester containing polyethylene terephthalate and polyether amine thus obtained can be melted and extruded to obtain monofilament or multifilament threads, as semi-finished products for the subsequent production of textile articles. The continuous filaments can be cut into fibers, which can then be used for producing nonwoven fabrics, or can be spun to obtain continuous filaments.
In other embodiments, the modified polyester can be produced starting from previously polymerized polyethylene terephthalate, for example in the form of chips, granules or the like, causing a functionalization reaction, through which molecules of polyether amine react with terminal groups of the molecules of polyethylene terephthalate, or with two consecutive monomers of the molecules of PET. The following reaction can take place between a chain terminal group of the polyethylene terephthalate and a generic polyether diamine H₂N-R-NH₂ obtaining the modified polyester with formation of ethanol:
When the molecule of polyether amine reacts with two monomers of polyethylene terephthalate inside the chain, vice versa, the following reaction will be obtained:
To facilitate the formation of polymer chains containing modified polyethylene terephthalate with the addition of molecules of polyether amine starting from polyethylene terephthalate already polymerized, chain extenders or grafters can be used to facilitate the formation of bonds between the molecule of polyether amine and the monomers of the polyethylene terephthalate. In some embodiments, a sequence of formaldehyde and bromoacetic acid can be used as chain extender. In a first step the previously polymerized polyethylene terephthalate reacts with the chain extender to form a polyethylene terephthalate functionalized with carboxyl group, according to the following reactions
The first reaction can be conducted at about 30°C for about 4 hours in acetic acid 1M, while the second at about 30°C in sodium hydroxide 2M for 18 h.
The molecules thus obtained can react with the respective terminal groups COOH through an amidation reaction with the polyether amine giving rise to the polyester containing polyether amine according to the following reaction:
where H₂N-R-NH₂ once again represents a generic polyether diamine, examples of which will be given below and were m represents the number of monomers of PET, of a molecule containing n monomers of PET that reacted with the polyether amine. The reaction can be conducted at about 120-140°C for 24 hours at atmospheric pressure. The value
The parameter n can be comprised between about 10 and about 1000. The parameter m can be comprised between 1 and 100.
The reaction above can take place in a batch process.
In other embodiments, the polyethylene terephthalate can be functionalized with polyether amine in a continuous process, in which the polyethylene terephthalate is reacted with polyether amine, with or without grafters or chain extenders, according to the reaction described above, in temperatures and pressure conditions such as to obtain the functionalization reaction in short times, compatible with the residence time of the reagents in a continuously fed volume.
For example, polyester and polyether amine can be fed into an extruder, both in the same position or in different positions along the longitudinal extension of the extruder, i.e. along the extension of the auger or other feeding system of the material along the extruder. For example, polyethylene terephthalate can be fed in a position upstream into a container with longitudinal extension containing a single or double feed auger. The polyether amine can be introduced downstream of the polyethylene terephthalate feed-in point, with respect to the direction of feed of the auger, in this way coming into contact with previously melted polyethylene terephthalate in a section upstream of the path defined by the feed auger. Downstream of the polyether amine feed-in point, this latter reacts with the polyethylene terephthalate in this way obtaining the polyester functionalized with polyether amine, which is then extruded in line.
If the reaction takes place with the use of one or more reaction facilitators, for example grafters or chain extenders as described above, these can be introduced together with the polyethylene terephthalate, or subsequently, for example between the polyethylene terephthalate feed-in point and the polyether amine feed-in point, or together with the polyether amine or downstream of the polyether amine feed-in point.
The molten mass of polyethylene terephthalate that has reacted or is reacting with the polyether amine can be extruded to produce threads or filaments, or other semi-finished products of indefinite length.
In some embodiments with functionalization in extrusion the polyethylene and the polyether amine can be made to react in the extruder with a residence time of 200-800 seconds, for example comprised between about 300 and about 700 seconds, preferably between about 450 and about 600 seconds, typically about 550 seconds. The residence temperatures can be comprised between about 250°C and about 350°C, preferably between about 270°C and about 310°C, for example, in particular about 290°C). The pressure in the extruder can, for example, be comprised between about 100 bar and about 300 bar, preferably between about 100 bar and about 250 bar. The polymeric mass of polyethylene terephthalate functionalized with polyether amine can be extruded with a total flow rate comprised between 10 and 20 kg/h, preferably between 12 and 18 kg/h, for example about 15 kg/h. Exemplary embodiments defined by specific parameters of the monofilament or multifilament thread are described below.
The starting polyethylene terephthalate can have a weighted average molecular weight (Mw) comprised between about 10,000 and about 40,000 and in some embodiments a relative viscosity (method: dichloroacetic acid in 1% solution) that can be comprised between about 0.4 and about 1.0 dl/g. In some embodiments the PET can contain percentages by weight of TiO₂ up to 2%, preferably up to 1.5%. Examples of polyethylene terephthalate useful for producing modified polyester as described herein, particularly for textile use, are: the polyester RT20 produced and marketed by INVISTA Resins & Fibers GmbH & Co KG, Germany; SM-01/D535, marketed by Novapet, Spain.
In other embodiments polyether monoamines, or polyether triamines can be used instead of polyether diamines as indicated by way of example in the previous reactions.
Functionalization processes in which polyethylene terephthalate reacts directly, with or without grafters or chain extenders, with the polyether amine can be of particular interest in the case in which the polyester functionalized with polyether amine is intended for the production of continuous threads, for example for textile use. In fact, in this case it is possible to use polyethylene terephthalate in chips and polyether amine as starting materials in an extrusion and spinning process, where the two components (PET and polyether amine) are brought into mutual contact, for example in the extruder, or in a pressurized chamber in fluid connection with the extruder, at the outlet of which the die from which the continuous thread is delivered is positioned.
In other embodiments, the modified polymer obtained by reacting PET and polyether amine can be converted once again into chips, granules or into other forms, different than thread, to be used subsequently in any converting process, for example molding, or extrusion.
Some details will be provided below of possible polyether amines that can be used in the production processes of the polyester containing polyethylene terephthalate and polyether amine, using any one of the methods described above.
While in the present description specific reference is made to examples in which a single polyether amine is used, i.e. only one type of polyether amine molecule, it must be understood that in some embodiments more than one polyether amine with different formulas can also be incorporated into the chain of the polyethylene terephthalate.
In some embodiments the polyether amine can be a polyether monoamine with general formula
where R = H for ethylene oxide and R = CH₃ for propylene oxide, and wherein x and y vary according to the number of propylene oxides and ethylene oxides present in the chain. Polyether monoamines of formula (1) are available, for example, from Huntsman Corporation, USA, with the trade name Jeffamine^® M series.
In preferred embodiments, the polyether amine has more than one free NH₂ group, so that in the reaction with the polyethylene terephthalate one of the NH₂ groups forms a covalent bond with the chain of the polyethylene terephthalate while the remaining NH₂ groups remain available.
In some embodiments, the polyether amine is a polyether diamine, of formula
where x, y and z can vary according to the number of ethylene oxides and propylene oxides present in the chain.
Polyether diamines of general formula (2) are available, for example, from Huntsman Corporation, USA, under the trade name Jeffamine^® ED series and Elastamine^® RE series.
In preferred embodiments, the polyether diamine has a weighted average molecular weight (Mw) equal to at least about 500, preferably equal to at least about 800, more preferably equal to at least about 1000, even more preferably equal to at least about 1500, and preferably no greater than about 5000, more preferably no greater than about 3000, for example comprised between about 1500 and about 2500.
An embodiment provides for the use of Elastamine^® RE-2000 (Huntsman) or Jeffamine^® ED2003, both of formula (1) wherein:

y is equal to about 39 and
(x+z) is equal to about 6,
and having a weighted average molecular weight (Mw) of about 2000.

In other embodiments polyether diamine of formula (2) with the following characteristics can be used:

y ≅ 12.5; (x+z) ≅ 6, weighted average molecular weight Mw = 900
y ≅ 9; (x+z) ≅ 3,6, weighted average molecular weight Mw = 600

Preferably, the polyether diamine has an AHEW (Amine Hydrogen Equivalent Weight) no greater than 10% with respect to the idealized AHEW. The term (AHEW) is defined as the weighted average molecular weight of the polyether amine divided by the number of active amine hydrogens per molecule. For example, an idealized polyether amine, having a weighted average molecular weight of 2000 and in which all the ends of the polyether are amine ends, hence contributing with 4 active amine hydrogens per molecule, would have an AHEW of 500 g per equivalent. If 10% of the ends are hydroxyl rather than amine, there will be only 3.6 active amine hydrogens per molecule and the polyether amine will have an AHEW of 556 g per equivalent.
The number of active amine hydrogens per molecule, and hence the AHEW of a given polyether amine, can be calculated according to prior art and conventional techniques, for example by calculating the nitrogen content of the amine groups using the procedure defined by the standard ISO 9702.
In particularly advantageous embodiments, the polyether amine is a polyether diamine, preferably having a weighted average molecular weight equal to or greater than 1500 and an AHEW that does not exceed by more than 10% the idealized AHEW for this polyether amine.
In embodiments described herein the polyether diamine has a general formula (2) and a composition of the chain with prevalence of PEG (polyethylene glycol) groups with respect to the PPG (polypropylene glycol) groups, i.e. with y >(x+z).
In other embodiments the polyether diamine can have a chain containing polyethylene glycol (PEG) and polypropylene glycol (PPG) groups with predominance of PPG groups. Polyether diamines of this type are available from Huntsman Corporation, with the trade name Elastamine^® RP series.
In yet other embodiments, the polyether diamine can have a base structure of polypropylene glycol and poly(tetramethylene ether glycol) (PTMEG). Examples of polyether diamines of this type are the polyether diamines marketed by Huntsman Corporation with the trade name Elastamine^® RT series.
Although the RE series polyether diamines with weighted average molecular weight equal to or greater than about 1500 and equal to or less than about 2500 are currently preferred, in particular for applications to polyesters intended for the production of fibers and threads, it would also be possible to use polyether diamines with a higher weighted average molecular weight, for example up to about 5000, such as Elastamine^® RP3-5000 (Huntsman). In other embodiments, the polyether diamine can have weighted average molecular weights (Mw) of less than 1500, for example no greater than 1000, or no greater than 800.
In other embodiments the polyether diamine has a chain composed of polypropylene glycol PPG groups, of general formula
Examples of polyether diamines of this type are polyether diamines of the Jeffamine^® D series produced and marketed by Huntsman Corporation, with weighted average molecular weight (Mw) variable from about 230 to about 4000 and in which x can vary from about 2.5 to about 68.
In yet further embodiments polyether amines with a number of amino groups (NH₂) greater than two can be used. For example, the polyether amine can be a polyether triamine of general formula
in which (x+y+z) can be comprised between 5 and 6 and the weighted average molecular weight Mw can be equal to about 440. In other embodiments the polyether triamine can have the general formula
with x+y+z comprised between about 50 and about 85 for average molecular weights (Mw) increasing from about 3000 to about 5000. Polyether triamines of this type are, for example, the Jeffamine^® T series produced and marketed by Huntsman Corporation, USA.
In some embodiments, the amount of polyether amine in the polyester can be comprised between about 1% and about 50% by weight, for example between about 2% and about 30%, preferably between about 2% and about 25% by weight, for example between about 2.5% and about 20% by weight, or between about 5% and about 20% by weight, with respect to the total weight of the polyester.
In some embodiments the polyester comprises an amount of polyethylene terephthalate of at least about 50%, preferably at least about 60%, more preferably at least about 70%, even more preferably at least about 80%, for example at least about 85% by weight with respect to the total weight of the polyester. In embodiments the percentage of polyethylene terephthalate is no greater than about 99%, preferably no greater than about 98%, for example no greater than about 95%, or no greater than about 90%, or no greater than about 85 % by weight with respect to the total weight of the polyester.
If the modified polyester containing polyether amine is used in a blend or in combination with other polymers, for example in the case of bi-component fibers, or in the case of blends with fibers, threads or filaments made with other polymers, the percentages of polyethylene terephthalate and of polyether amine indicated above are referred to the total weight of the polyester containing polyethylene terephthalate and polyether amine, excluding the weight of any second or further blended polymer.
The polyester usable can have a molar mass for example comprised between about 1,000 and about 1,000,0000 g/mol. In some embodiments, the polyester has a molar mass between about 2,000 and about 1,000,000 g/mol.
The polyester described herein can be advantageously used for producing semi-finished products intended for the textile industry, in the form of continuous thread or of staple fiber. The thread can be monofilament or multifilament.
The thread can be obtained by extrusion and the staple fiber can be obtained by cutting the extruded continuous thread. The thread obtained from extrusion of the polymer according to the method described herein can be a multifilament textile thread of the LOY (low orientation yarn), POY (Partially Oriented Yarn), or FDY (Fully Drawn Yarn) type.
If the thread is cut into fibers, the fibers can, for example, have a length comprised between about 2 and about 200 mm, preferably between about 10 and about 100 mm. The staple fibers can be converted into continuous filaments using known spinning processes.
According to another aspect, the staple fibers can be used for producing nonwoven fabrics, forming plies of fibers subsequently subjected to mechanical, hydraulic, chemical or thermal bonding processes, or combinations thereof.
The threads or yarns can be used in weaving processes, knitting processes or for other uses.
Threads produced with the process described herein can subsequently be processed to modify their physical and mechanical characteristics. In some embodiments, the threads can be combined with other threads to obtain composite articles. In some embodiments the threads obtained from the spinneret can be texturized, or taslanized, stretched, combined with elastomeric threads for example through an interlacing or covering jet, or other suitable device.
The thread or the fiber can be mono-component. In this case the filament or filaments of which it is formed consist of a single material.
In other embodiments, the thread can be multi-component, for example bi-component. One, some or each filament forming the thread comprises, in this case, two parts formed by two different polymers. In some embodiments the filament comprises an inner core and an outer coating ("core-skin" bi-component fiber) produced in different polymers. According to possible embodiments, the outer part, or skin, that surrounds the inner core can be produced with polyester containing polyethylene terephthalate and polyether amine, while the core can be produced with a different polymer.
In some embodiments the bi-component fiber can have a second component consisting of or comprising polyamide, polypropylene or thermoplastic polyurethane, or polyester, for example polyethylene terephthalate or polybutylene terephthalate, without polyether amine.
In other embodiments the two components that form each filament can be side by side with one another ("side-by-side" bi-component fiber), rather than inserted one inside the other.
Extrusion heads for producing multi-component, in particular bi-component, threads are known and can be used advantageously in the context of the methods described herein.
In some embodiments, bi-component threads can be produced in which from 10% to 95% by weight, preferably from 50% to 80% by weight, of the polymer of which they are composed is a polyester containing polyethylene terephthalate and polyether amine, while the remaining part consists of polyamide, non-modified polyester, i.e. without polyether amine, or a polymer of another kind, for example polypropylene.
According to the use for which it is destined, the thread can have a number of filaments comprised between 1 (monofilament) and 10,000. In some embodiments the thread can have a count comprised between about 5 and about 6000 dtex, preferably between about 5 and about 5000 dtex, for example between about 5 and about 3000 dtex.
In some embodiments the thread is extruded with a number of filaments comprised between 1 and 300, for example between 5 and 200.
In advantageous embodiments the thread can have a DPF (dtex per filament) value comprised between 0.3 and 20, for example between 0.4 and 20.
In some embodiments, in particular for example for use in the production of garments, the thread can have a number of filaments comprised between 1 (monofilament) and about 100, preferably between about 30 and about 80, in some embodiments between about 40 and about 75, and a count comprised between about 7 and about 140 dtex, preferably between about 40 and about 120 dtex, for example between about 50 and about 100 dtex, in some embodiments about 90 dtex.
In some embodiments the polymer is extruded at an extrusion speed between 20 and 80 cm/s. The filaments exiting from the spinneret can advantageously be cooled in a known manner, for example in a current of air.
In this step the single filaments are cooled with a lateral flow of air and made to converge toward and through an oiler to be thus combined to form a multi-filament thread. Downstream the thread can be fed around one or more stretching and/or relaxing and/or stabilizing rollers, motorized and controlled at peripheral speeds that can differ from one another to give the thread the required and desired degree of stretch and/or orientation.
The thread can be subjected to a stretching and/or texturizing, with elongation percentages comprised between about 15% and about 200%. In some embodiments the thread is subjected to elongation comprised between 20% and 150%.
Finally, the thread is wound to form a reel or package. The winding speed can be comprised between about 1000 and about 5500 m/min, preferably between about 2000 and about 3500 m/min, for example between about 2500 and about 3000 m/min, in some embodiments about 2800 m/min.
It has surprisingly been discovered that a thread or yarn made with a polymer based on functionalized polyester terephthalate, as described above, by means of a polyether amine, has a dyeability, i.e. a capacity to absorb and retain a dye, much greater than a standard PET, commonly used for producing threads or yarns and which also has considerable advantages with respect to cationic PETs. Therefore, the polyester terephthalate described here makes it possible to carry out dyeing cycles that are simpler, less onerous from the point of view of energy consumption and environmental impact and with lower consumptions of materials or with the use of less costly materials.
In order to better understand the many advantages that can be obtained during dyeing with a PET functionalized as described herein, the operating parameters of three dyeing cycles, obtained with a standard PET, with a cationic PET of the state of the art and with a PET functionalized with polyether amine as described herein, will be compared below. For a better understanding of the dyeing cycles and of the related advantages, the aforesaid three cycles will be described with reference to the accompanying Figs. 1, 2 and 3, which provide diagrams with the times (in minutes) of the steps of a dyeing cycle shown on the abscissa and the temperatures (in °C) of the various steps shown on the ordinate.
With initial reference to Fig.1, this shows a time-temperature diagram, in which the dyeing cycle performed with a standard PET is summarized. In the case being examined a polyester RT20 manufactured by INVISTA was used to produce a textured thread DTY 50dtex/68filaments.
Garment dyeing was carried out, i.e. dyeing of the finished garment, but similar results are also obtained if the textile product is yarn-dyed, i.e., introducing reels of wound thread, destined for the subsequent production of garments, into the dyeing machine.
The dyeing cycle of Fig.1 is carried out with a water-based bath, containing a dispersant and a dye for polyester. The article to be dyed is placed in the bath at about 40°C for a duration of about 15 min. This temperature is defined here as a pre-dyeing temperature. Subsequently, a heating step up to 130°C is carried out. To prevent the dye bath from boiling, the process is carried out in an autoclave or in any case in a pressurized container, where the operating pressures can typically reach 0.7 bar.
The overall dwell time of the product in the bath can typically be about 120-125 minutes. In general, the dwell time at 130°C is about 30 minutes. The dyeing step is followed by a cooling step at 40°C and stripping at about 80°C, to eliminate the excess dye from the thread. The stripping step takes about 50 minutes and is followed by a finishing step in which additives are added to soften the fabric or yarn and obtain the desired consistency to the touch, with soft and pleasant hand.
Pressurized dyeing apparatus are complex and require regular testing and inspection operations, which are costly and have a negative impact on the availability of the machinery and therefore reduce the overall productivity of the system. Moreover, the operation of these systems raises problems of safety, as has been intrinsically shown by the mandatory need for regular testing and inspection.
To overcome these problems, in place of standard polyester cationic polyesters are at times used to produce thread and garments. Reels or garments made of thread based on cationic polyester are dyed with cycles of the type shown in Fig.2. The product to be dyed is introduced into a water-based bath containing basic dye, a dispersant and a carrier, having the function of accelerating the dyeing times. The bath is heated from a temperature of 40°C (pre-dyeing temperature) to a temperature of 98°C at which it is maintained for the necessary time. This step requires a total of about 225 minutes. The dwell step at 98°C can typically last for 120-140 minutes and is therefore considerably longer with respect to the high temperature step of the dyeing cycle of standard PET.
As the maximum temperature reached is lower than the boiling temperature of the water at ambient pressure, the cycle can be carried out at ambient pressure without requiring pressurized tanks. This is followed by stripping and finishing steps, just as for conventional PET.
Dyeing cationic PET has the advantage of not requiring pressurized vessels, but in order for it not to require execution times incompatible with the requirements of a sufficiently high productivity of the system, it is necessary to use carriers to accelerate the dyeing process. In any case, as mentioned above, the dwell times of the product to be dyed at the highest temperature of the cycle are about four times higher than the times required to dye standard PET. Dyeing cationic PET also requires double the amount of dye with respect to standard PET (Fig. 1).
Fig.3 shows, similarly to Figs. 1 and 2, the steps of a dyeing cycle of a modified PET, i.e. functionalized with polyether amine, according to the description above. The dyeing cycle is substantially equivalent to that of standard PET with regard to the succession of the steps and the time of each step. Moreover, as can be seen in Fig.3, the duration of the initial bath step (at the pre-dyeing temperature) and high temperature bath (dyeing temperatures), up to lowering of the temperature to 40°C for the start of the stripping step, can be lower with respect to the cycle for dyeing standard PET. In the second case, Fig.1 indicates a time of about 125 minutes, while in Fig.3 it can be observed that the dyeing cycle of a PET modified as described herein requires an actual dyeing step of 110 minutes, followed by cooling at 40°C and subsequent stripping. The lower dwell time is justified by the fact that dyeing takes place at temperatures lower than 100°C, typically between 90°C and 99°C. In the example illustrated dyeing takes place at 98°C. This temperature can be reached in shorter times with respect to those required to reach the 130° C required for dyeing standard PET.
Moreover, and more importantly, the temperature of the dyeing cycle of the PET functionalized with polyether amine is below boiling temperature and therefore does not require equipment with pressurized tanks. The lower operating temperature also implies an energy saving.
In total, with respect to the cycle of Fig.1, the dyeing cycle of the cationic polyethylene terephthalate implies an energy saving of about 10-15%, while the dyeing cycle of the PET functionalized or modified with polyether amine as described here implies an energy saving of about 32%. Added to this, with respect to standard PET, is a saving of 10% on the cost of the machinery, equivalent to the saving obtainable with cationic PET. However, the reduced cycle times obtainable with the PET functionalized with polyether amine increases the total productivity of the system due to a reduction of 75% of the time required for the actual dyeing step.
The cooling time from the dyeing temperature (98°C in the case of the dyeing cycle of Figs. 2 and 3 and 130°C in the case of the dyeing cycle of Fig.1) to the cooling temperature (in the example 40°C) preceding the stripping step is not represented in the diagrams, as the bath is replaced at the end of the dyeing step. The discharge times of the dye bath and the introduction time into the stripping bath are very short and not represented in Figs. 1, 2, 3.
However, in some cases it can be advisable to carry out a preliminary cooling step of the dye bath to reduce the temperature of the yarn before replacing the bath, in order to avoid or reduce thermal shock on the yarn. Figs. 4, 5 and 6 show the same dyeing cycles as Figs. 1, 2 and 3, respectively, but in which a cooling step from the dyeing temperatures to an intermediate temperature of 80°C is added, before discharging the dye bath and replacing it with the stripping bath at 40°C. This cooling step has a duration of about 40 min in the case of dyeing cycle with standard PET, with initial temperature (dyeing temperatures) of 130°C. Vice versa, in the case of dyeing cationic PET and PET modified according to the present invention, the cooling step has a shorter duration, of about 20 minutes, as the starting temperature is lower (98°C in the example illustrated).
This highlights a further advantage of the dyeing cycle according to the present invention over the dyeing cycle with conventional PET, consisting in the further reduction, in the example of 20 minutes, of the total duration of the dyeing cycle.
The reduced operating temperature of the dyeing machines also allows a saving on the processing costs of the thread, as a thread with lower features of resistance to temperature can be used.
In total, at current market conditions, moreover, the cost of the raw material for production in the case of cationic PET is about 30% higher than standard PET, while the PET modified with polyether amine has a cost equal to or slightly higher (about 10% higher) than the cost of standard PET.

Dyeing of the PET modified with polyether amine is carried out with normal dyes dispersed for dyeing standard PET, carrying out a thermodynamic control in the case of two colors and three colors, to verify dye affinity as they are used at a temperature below 100°C. The use of the dispersant is variable based on the intensity of the shade to be obtained. The tables below provide four dyeing recipes that can be used to dye PET modified with polyether amine according to the present description. The products indicated as "Prochimica" are available from Prochimica Novarese S.p.A., Novara, Italy. The production indicated as Archroma are available from Archroma Management GmbH, Basel, Switzerland. The amounts of dispersant and chemical agent for controlling the pH are indicated in grams per liter of dye. The amount of dyes is indicated in percentage by weight referred to the weight of the material (e.g. thread) to be dyed.

Example of Prochimica Tan (medium-light) color
Prochimica Egalen	TPL	(dye dispersant)	2	g/liter
Acetic	Acid	(chemical agent for pH 5/5.5)	2	g/liter
				% thread
Prochimica Tersol	Yellow	V-2R	0.517	weight
				% thread
Prochimica Tersol	Red	V-RL	0.455	weight
				% thread
Prochimica Tersol	Blue	V-BL	0.253	weight

Example of Archroma Tan (medium-light) color
Archroma	Setamol	WS	(dye dispersant)	2	g/liter
	Acetic	Acid	(chemical agent for PH 5/5.5)	2	g/liter
					% thread
Archroma	Lumacron	Yellow	SE3G	0.517	weight
					% thread
Archroma	Foron	Bright red	E-2BL	0.377	weight
					% thread
Archroma	Foron	Blue	EBL	0.349	weight

Example of Prochimica black color
Prochimica	Egalen	TPL	(dye dispersant)	1	g/liter
	Acetic	Acid	(chemical agent for PH 5/5.5)	2	g/liter
					% thread
Prochimica	Tersol	Black	H-MTL/2	6	weight

Example of Archroma black color
Archroma	Setamol	WS	(dye dispersant)	1	g/liter
	Acetic	Acid	(chemical agent for PH 5/5.5)	2	g/liter
					% thread
Archroma	Lumacron	Black	SEF	6	weight

Claims

A method for dyeing a textile article made at least partly of polymer fiber or polymer yarn, comprising the steps of:
introducing the textile article comprising polyethylene terephthalate and a polyether amine into a dye bath;

dyeing the textile article with a dyeing temperature of the bath no greater than 100°C and preferably between about 90 and about 99°C at ambient pressure for a time interval comprised between about 10 minutes and about 60 minutes
The method of claim 1, wherein the textile article consists at least partly of a terpolymer consisting of polyester functionalized with polyether amine.
The method of claim 1 or 2, wherein the step of dyeing the textile article comprises maintaining the textile article at the dyeing temperature for a time interval comprised between about 20 minutes and about 40 minutes, preferably comprised between about 25 minutes and about 35 minutes.
The method of one or more of the preceding claims, further comprising a preliminary step wherein the textile article is maintained in the dye bath at pre-dyeing temperature, lower than the dyeing temperature, said pre-dyeing temperature preferably being equal to or less than 50°C and preferably equal to or greater than 30°C, preferably about 40°C.
The method of one or more of the preceding claims, comprising a subsequent stripping step, at a temperature preferably no greater than 90°C and preferably no lower than 70°C, preferably about 80°C.
The method of claim 5, wherein between the dyeing step and the stripping step there is provided a gradual cooling step in the dye bath from the dyeing temperature to an intermediate temperature and a subsequent step of draining the dye bath and replacing with a stripping bath at a temperature lower than the intermediate temperature.
The method of one or more of the preceding claims, wherein the polyether amine is mainly positioned as chain terminal in the polyethylene terephthalate, with an amino terminal (NH₂).
The method of one or more of the preceding claims, wherein the polyether amine is a polyether diamine or a polyether triamine.
The method of one or more of the preceding claims, wherein the polyether amine is present in a percentage equal to at least about 1% by weight, preferably equal to at least about 2% by weight, more preferably equal to at least about 5% by weight, with respect to the total weight of the polyester; and wherein the percentage by weight of the polyether amine is no greater than about 50% by weight, preferably no greater than about 30% by weight, more preferably no greater than about 25% by weight, even more preferably no greater than about 20% by weight, with respect to the total weight of the polyester.
The method of one or more of the preceding claims, wherein the polyester comprises a percentage of polyethylene terephthalate of at least about 50% by weight, preferably at least about 60% by weight, more preferably at least about 70% by weight, even more preferably at least about 80% by weight, with respect to the total weight of the polyester; and wherein preferably the percentage by weight of polyethylene terephthalate is no greater than about 99%, preferably no greater than about 98% by weight, even more preferably no greater than about 95% by weight, with respect to the total weight of the polyester.
The method of one or more of the preceding claims, wherein the polyether amine has a weighted average molecular weight (Mw) equal to at least about 500, preferably equal to at least about 800, more preferably equal to at least about 1000, even more preferably equal to at least about 1500, and preferably no greater than about 5000, more preferably no greater than about 3000.