Method for Producing Colored Yarns And/Or Colored Fabrics in Particular Without or with Only Limited Amount of Wastewater Discharge

This application claims the benefit under 35 U.S.C. 119(a) to European Patent Application No. 24 165 956.4, filed 25 Mar. 2024, the disclosure of which is incorporated herein by reference in its entirety.

The present invention relates to the technical field of yarn and/or fabric production.

In particular, the present invention relates to a method for producing a colored yarn based on synthetic fibers.

Furthermore, the present invention relates to a method for producing a colored fabric based on synthetic fibers.

Furthermore, the present invention relates to a use of a spinning additive in a method for producing a colored yarn based on synthetic fibers and/or for producing a colored fabric based on synthetic fibers.

Furthermore, the present invention also relates to a colored yarn comprising a spinning additive, wherein the spinning additive is self-elutable and/or self-sluicing upon washing the yarn with an aqueous solution.

Furthermore, the present invention also relates to a colored fabric obtained by a method for producing a colored fabric based on synthetic fibers.

The present invention, in particular the methods recited above, according to a preferred embodiment of the present invention and/or the recited methods, further include measures to perform the inventive methods without or with only limited discharge of wastewater.

The coloring or dyeing of textiles and yarns has been carried out industrially since the 19th century. Aqueous color solutions and/or color dispersions can be used, to which other auxiliary chemicals, such as salts, acids and alkalis, as well as color additives are added. These chemicals are intended to support the coloring or dyeing process, and beyond this are not needed in the further textile or fabric production. Hence, after coloring, the colorants and auxiliary chemicals are washed out. This results in large quantities of wastewater that is contaminated with the colorants and auxiliary chemicals and has to be cleaned at great expense. The high water demand and the chemicals used are particularly harmful to the environment.

The so-called dope-dyeing process is known to reduce the environmental impact. The dope-dyeing process is used to produce synthetic fibers or yarns based on polymers. A colorant is added to a polymer (granulate or melt) as a base material. The polymer-colorant mixture can then be processed into a homogeneous melt using an extruder, for example, and can be fed through a spinneret to produce fibers and/or yarn. A spinning additive must be added in order to feed the polymer melt through the spinnerets and form fibers without breakage or damage. The fibers can be wound up individually as a monofilament yarn or into several fibers as a multifilament yarn. The resulting yarn is already colored and can then be processed directly into a colored fabric and/or textile. In this way, the use of colorants and auxiliary chemicals can be reduced. The fabric and/or textile is washed to remove auxiliary chemicals, spinning additives and any other processing additives used. With the help of the dope-dyeing process, the use of chemicals can be reduced, thereby reducing the environmental impact. However, despite the improvements, the burden on the environment and workers in production remains comparatively high.

Against the background of the state of the art described above, the object of the present invention is thus to provide a method for producing a colored yarn and/or fabric which is more environmentally friendly and requires less water consumption. Furthermore, the process should be easy and inexpensive to carry out.

To solve the problem described above, the present invention thus proposes—according to a first aspect of the present invention—a method for producing a colored yarn based on synthetic fibers. Respective advantageous further embodiments and configurations of this aspect of the invention are subject-matter of the dependent claims relating thereto.

Further subject-matter of the present invention—according to a second aspect of the present invention—is a method for producing a colored fabric based on synthetic fibers. Respective advantageous further embodiments and configurations of this aspect of the invention are subject-matter of the dependent claims relating thereto.

Further subject-matter of the present invention—according to a third aspect of the present invention—is a use of a spinning additive in a method for producing a colored yarn based on synthetic fibers and/or for producing a colored fabric based on synthetic fiber. Respective advantageous further embodiments and configurations of this aspect of the invention are subject-matter of the dependent claims relating thereto.

Again further subject-matter of the present invention—according to a fourth aspect of the present invention—is a colored yarn comprising a spinning additive, wherein the spinning additive is self-elutable and/or self-sluicing upon washing the yarn with an aqueous solution and/or wherein the spinning additive is water-soluble. Respective advantageous further embodiments and configurations of this aspect of the invention are subject-matter of the dependent claims relating thereto.

Again further subject-matter of the present invention—according to a fifth aspect of the present invention—is a colored fabric obtained by a method for producing a colored fabric based on synthetic fibers. Respective advantageous further embodiments and configurations of this aspect of the invention are subject-matter of the dependent claims relating thereto.

It goes without saying that configurations, embodiments, advantages and the like, which are listed below for the purpose of avoiding repetition with respect to only one aspect of the invention, naturally also apply correspondingly with respect to the other aspects of the invention, without this requiring separate mention.

Furthermore, it goes without saying that, in the case of the following specifications of values, figures and ranges, the relevant specifications of values, figures and ranges are not to be understood as limiting; it goes without saying for the person skilled in the art that it is possible to deviate from the specified range or specifications on a case-by-case or application-related basis without departing from the scope of the present invention.

In addition, all the values or parameters or the like mentioned below can in principle be determined using standardized or standardized or explicitly stated determination methods or using determination methods known to a person skilled in the art onto this field.

Furthermore, in the case of all the relative or percentage, in particular weight-related, quantities stated below, it should be noted that these figures must be selected or combined by the skilled person with regard to the reference system used (e.g. dosage form) in such a way that the total-if necessary including further components or ingredients or additives or constituents, in particular as defined below-always results in 100% or 100 wt. %. However, this is self-evident to the person skilled in the art.

Furthermore, for the description of the present invention, the features of the present invention mentioned in each case in the context of the specific configurations, embodiments, advantages, examples or the like are also deemed to be disclosed in their combination. Thus, superordinate combinations of individual or several features which are cited for respective configurations, embodiments, examples of use or the like are also deemed to be disclosed in the present case.

In particular, for the features characterizing the invention, all possible combinations of these features are deemed to be disclosed, wherein embodiments of comparable or according to preference of the various features are preferably combined (e.g. quantities or quantity ranges of the related parameters of the same preference or the like).

In particular, it is also the case that, for the following details relating to the various parameters of the method according to the invention or the like, combinations of the same preference or the same preference level and relating to the various parameters are also disclosed with according to preference or preference. Likewise, all other combinations (i.e. combinations onto different preferences or different preference levels) are also disclosed.

With the foregoing in mind, the present invention is now explained in detail below:

Subject-matter of the present invention—according to a first aspect of the present invention—is a method for producing a colored yarn based on synthetic fibers. The method comprises the addition of a spinning additive, which preferably facilitates processing, in particular spinning, and prevents damage to the fibers during spinning.

It is envisioned that the spinning additive is self-elutable and/or self-sluicing upon washing the yarn and/or a fabric spun from the yarn with an aqueous solution and/or the spinning additive is water-soluble. In particular, the spinning additive is soluble in pure water. “Soluble in pure water” in the context of the present invention means soluble in water under ambient conditions without the need for the addition of detergents.

The spinning additive can therefore be easily removed from the yarn and/or textile and/or fabric produced of the yarn by washing with water. It is then possible to avoid using detergent when washing the yarn and/or fabric to largely reduce the amount of detergent used. By saving on detergents, the wastewater produced during the washing process is less contaminated, making it easier to treat the wastewater. At the same time, fewer environmentally harmful substances need to be disposed of. As the wastewater is less contaminated, the treated water can be reused more frequently to wash the textile, yarn or fabric, which can reduce the overall water requirement in yarn, textile and/or fabric production. Overall, the impact on the environment can be significantly reduced compared to the use of conventional spinning additives.

Further in the context of the present invention, the terms fabric and textile are used synonymously and understood to relate to a material, in particular cloth, produced by in particular weaving, or knitting, fibers spun to a yarn.

Preferably, the method for producing a colored yarn includes and/or is a dope-dyeing process. The dope-dyeing process is a well-known and established method that has been used for a long time to produce colored yarns. It is then possible to carry out the process in a particularly simple way with existing plants without any modifications.

In particular the addition of the spinning additive is performed while providing a base material for producing the yarn and/or while performing the dope-dyeing process. The spinning additive can then be added directly to the base material or added at a later stage in the process, which can increase flexibility.

The dope-dyeing process can comprise the method steps of providing the base material as a molten polymer and/or extruding the base material and spinning a yarn from the molten and/or extruded base material. In particular, the addition of the spinning additive is performed while providing the base material for extruding and/or as a polymer melt and/or while extruding the base material and/or while spinning a yarn from molten and/or extruded base material. The spinning additive can then be added in a particularly flexible manner and adapted to the specific application.

In the context of the invention, the term “extrusion” and/or the term “extrude” means melting of the plastic (granular) base material and providing of a constant melt flow of the molten plastic base material.

To enable the yarn to be colored evenly and easily, the base material for producing the yarn comprise a color masterbatch material and a plastic granular base material. Such color masterbatches are inexpensive and commercially available. Color masterbatches can be used to produce yarns from any color.

The method for producing a colored yarn based on synthetic fibers, can comprise the following method steps in the following order:

In at least one of the method steps a), b) and/or c) a spinning additive can be added, wherein the spinning additive is self-elutable and/or self-sluicing upon washing the yarn and/or a fabric spun from the yarn with an aqueous solution and/or the spinning additive is water-soluble. The spinning additive can be added to the process in a flexible manner.

The spinning additive is preferably added in only one of the method steps a), b) and c), preferably in method step b) or c). In particular, the spinning additive is added only in method step c). The spinning additive is then only added to the polymer melt at the point where the additive is required. In this way, damage to the additive during extrusion can be avoided.

The method steps b) and c), in particular a), b), and c), are preferably carried out continuously and/or without interruption consecutively, in particular within one production line. This is particularly advantageous when producing large quantities of yarn.

Alternatively, the method steps a), b), and/or c), in particular method step a), can be carried out discontinuously and/or with interruptions, in particular in from another different and/or separated production lines. In this way, a high degree of flexibility and decentral-ized production can be achieved.

The plastic granular base material preferably comprises and/or is a thermoplastic polymer material, in particular a thermoplastic polymer material selected from the group of polyolefins, polyesters, polyamides, polyacrylates, polyethers, polyacetals, polyurethanes, polystyrols and mixtures thereof, in particular polyolefins, polyesters, polyamides, polyacrylates and mixtures thereof. The most common synthetic yarns can then be produced.

The plastic granular base material usually is in the form of free-flowing bulk-goods, wherein the granules have sand- or grain-like shape and/or size.

The color masterbatch material can comprises at least one, in particular with the plastic granular base material compatible, colorant and, optionally, at least on dispersant, wherein the colorant and optionally the dispersant are comprised in a, in particular with the plastic granular base material compatible, resin matrix. The term “compatible with the plastic granular base material” means that the color masterbatch material, in particular the colorant and the resin material, is/are selected such that the color masterbatch material is mixable and/or fusible with the plastic granular base material, in particular upon melting and/or extruding in step b). To ensure good compatibility, the resin matrix preferably is selected from the same thermoplastic polymer materials than the plastic granular base material used. The colorant is preferably selected such, that the average particle size and/or the average particle diameter of the colorant is, in particular much, smaller than the average fiber diameter. In this way, a particularly uniform coloration of the yarn can be achieved. Further, a reliable fiber strength is ensured.

The color masterbatch material can be provided and/or mixed with the plastic granular base material, in particular in method step a), in an amount in the range of 0.05 wt. % to 10 wt. %, in particular 0.1 wt. % to 5 wt. %, preferably 0.25 wt. % to 4 wt. %, more preferably 0.4 wt. % to 3.5 wt. %, based on the weight of the plastic granular base material to achieve a particularly homogeneous coloration of the yarn.

The, in particular mixed, color masterbatch material and plastic granular base material can be dried in particular during or after method step a) and/or prior to method step b), preferably at temperatures above 100° C., preferably at temperatures in the range from 110° C. to 160° C., more preferably at temperatures in the range from 130° C. to 150° C., and/or in particular under such conditions, that the moisture content of the, in particular mixed, color masterbatch material and plastic granular base material is below 1%, preferably below 0.5%, more preferably below 0.1% after drying. This prevents fiber breakage and increases the strength of the yarn.

In particular in method step b), the mixed color masterbatch material and plastic granular base material is preferably melted by heating the mixed materials to a melting temperature above the melting point of the plastic granular base material, in particular wherein the melting temperature is set to 10° C., in particular 30° C., preferably 50° C., above the melting point of the plastic granular base material. In this way, a particularly homogeneous plastic melt with evenly distributed colorants can be achieved.

Preferably, the, in particular in method step c), molten mixed color masterbatch and plastic base material is fed through a nozzle, in particular a spinneret, under high pressure. In particular, the mixed color masterbatch material and plastic granular base material melted in step b) can be fed into the nozzle, in particular the spinneret, under high pressure. The melted mixed color masterbatch material and plastic granular base material exits the nozzle in particular into air, preferably such, that the viscous material stream solidifies to form the colored synthetic fiber and/or yarn. The term “high pressure” preferably means a pressure of 1 to 150 MPa, preferably of 2 to 100 MPa, more preferably of 3 to 50 MPa.

In at least one of the method steps a), b) and/or c), the added spinning additive can comprise at least one surface-active substance based on ethylenoxide, propylenoxide and mixtures thereof, in particular polyethylenoxide, polypropylenoxide and copolymers and mixtures thereof. Corresponding spinning additives can be washed out without detergents.

Additionally or alternatively, the surface-active substance can be a substance from the group of polyethers, in particular polyether homopolymers, polyether copolymers, preferably polyether block-copolymers, mixed ether-polyether-compounds and mixtures thereof, in particular wherein the polyether is a polyether of ethylenoxide, propylenoxide and mixtures thereof. In particular the surface-active substance is selected from the group of glycerol ethoxylate, polyoxyethylene-polyoxypropylene block-copolymers (Poloxamer), potas-siam polyoxyethylene laurylether phosphate, and mixtures thereof. Corresponding spinning additives can be washed out without detergents.

In at least one of the method steps a), b) and/or c), the added spinning additive can comprise at least one film-forming substance based on carbohydrates, modified carbohydrates and polymers and mixtures thereof, in particular modified carbohydrates and polymers and mixtures thereof, preferably modified chitosan, modified cellulose and polymers and mixtures thereof. Preferably, the film-forming substance is selected from the group of cellulose ether, glycol chitosan, carboxymethyl chitosan, trimethyl chitosan, and mixtures thereof, preferably carboxymethyl chitosan. Corresponding spinning additives can be washed out without detergents and are largely harmless to the environment.

In at least one of the method steps a), b) and/or c), the added spinning additive can comprise in addition surfactants, preservatives, lubricants, in particular plant-based lubricants, preferably vegetable oil, and/or stabilizers.

After the spinning step, the colored synthetic fiber and/or yarn obtained in method step c) is wound up onto a spool. Depending on the intended use, yarns can—in that step—also be stretched or the like within a pre- and/or post-processing treatment. Also, composite yarns can be formed by combining yarns made from different plastic granular base material with another.