PL248741B1 - Method for obtaining granulate containing recyclate from textile waste - Google Patents

Abstract

The subject of the application is a method for obtaining granulate containing recyclate from textile waste according to the invention, which is characterized in that the textile waste material is transformed into a powder—textile recyclate—using cryogenic grinding. The resulting powder is combined with: a) a commercial polymer material, or b) polymer recyclate, or c) a mixture of polymer material and recyclate (a) + b)), creating a mixture that, after melting, produces a composite material—thermoplastic + textile recyclate, which is transformed into a filament of a predetermined diameter. The resulting filament is cut into commercial granulate.

Description

The subject of the invention is a method for obtaining granulate containing recyclate from textile waste.

The term "textiles" encompasses various types of fabrics, knits, and nonwovens, primarily produced by the clothing industry, but also widely used in the furniture, automotive, agricultural, hospitality, environmental protection, medical, and other industries. Textiles encompass natural materials such as cotton, cotton derivatives such as viscose, and a wide range of synthetic materials, including polyesters, polyamides, polyurethanes, and other synthetics. A fundamental and fundamental hurdle in textile recycling is the fact that these materials are often mixed materials, meaning they can be made from natural, artificial, or synthetic fibers, which significantly complicates the recycling process. Regardless of what the textiles are made of and how long they will ultimately be used, they lose their original properties under the influence of external factors and time, becoming waste. The simplest way to reuse textile waste is, for example, to donate clothes to those in need or use them as fuel. In advanced solutions, waste textiles are processed by completely converting the initial waste made of polyethylene terephthalate, known as PET, into a material for reuse in the textile industry.

The American invention US20110236678A1 is known for its method of recycling used clothing and home textiles, where textile waste is sorted according to its properties and subjected to modification, which includes the removal of undesirable materials such as rubber, glue, etc. The textile waste is then reduced in volume and mixed with resin, and then formed into the appropriate shape.

US patent US11021589B2 describes a method for recycling polyester textile waste. Polyester textiles impregnated with a mixture containing a solvent and a catalyst are subjected to high temperatures in the range of 80-240°C during depolymerization of the polyester in said polyester textiles. The catalyst used contains calcium oxide.

U.S. Patent No. 10501599B2 discloses methods for recycling cotton and polyester fibers from textile waste. These methods involve a subcritical water reaction to recycle cellulosic and polyester components from cotton and cotton/polyester blend textile waste that would otherwise be discarded or disposed of. Specifically, the disclosed methods treat waste textiles to produce advanced materials, including cellulose and terephthalic acid (TPA), with low environmental impact. The resulting cellulose and TPA are of high quality, enabling the production of regenerated cellulose and regenerated polyethylene terephthalate (PET) suitable for fiber spinning and textile applications.

A process for recycling plastics, products, and their applications is known from patent application publication No. WO2013057737A2. This process comprises: separating plastic waste collected from various sources and then cleaning the segregated plastic waste to obtain segregated, cleaned waste; shredding the segregated, cleaned waste to obtain shredded waste; feeding the shredded waste into an extrusion line having a venting extruder component as part of the extrusion line to obtain molten plastic; and removing contaminants by vacuum venting the molten plastic to obtain contaminant-free recovered plastic.

European invention No. EP1036641A1 discloses a process for recycling ABS plastics which is accomplished by first shredding used plastics to produce shredded plastics, separating metals and undesirable plastics from the shredded plastics to produce separated plastics, analyzing the material composition of the separated plastics, and mixing the separated plastics to produce the desired recycled plastic.

A method for producing a composite of a thermoplastic polymer with natural fibers by mixing sections of natural fibers with a thermoplastic polymer, heating the mixture and extruding is known from Polish patent description No. PL208532B1, which is characterized in that the natural fibers are cut into fragments 0.0003-0.010 m long, then added to the thermoplastic polymer in quantities of 25 to 80 weight units, the components are mixed and the obtained mixture is extruded at the processing temperature of the polymer being the matrix of the composite to obtain granulate.

A method for producing a composite material from textile waste and waste polyethylene film is known from the Polish patent application no. PL429361A1, comprising the following steps: a) shredding textile fibers from textile waste into a fraction of up to 15 mm, b) shredding polyethylene film into a fraction of up to 15 mm, c) separating metal parts from shredded textile fibers, d) separating metal parts and plastics that are not foil flakes from shredded polyethylene film, e) further shredding textile fibers into a fraction of up to 5 mm, f) mixing shredded textile fibers with shredded polyethylene film, wherein textile fibers constitute 10-50% of the mixture, g) plasticizing, homogenizing and extruding the obtained mixture in an extruder at a temperature of 170-240°C and under pressure. 8-15 MPa.

Polish patent no. PL237721B1 describes a method for producing granules and microgranules containing plastics, in which the plastic and additional components are dispensed, mixed, compacted, and forced through passageways. The pressing through the passageways is accomplished using compression rollers, and the plastic and additional components are dispensed into the passageways using a dispenser and distributed using a spreader bar. The passageways move relative to the compression rollers and the spreader bar.

Polish patent no. PL234858B1 describes a method for producing a recycled polyolefin composite. This method involves mixing and grinding plastic waste, removing solid contaminants from the resulting mixture, and then subjecting the mixture to preliminary washing and grinding, followed by washing. The washed mixture is subjected to flotation, water is removed from the mixture, and the mixture is dried with a stream of hot air. The mixture is then mixed with filler, extruded, and regenerated. The resulting regranulate is packaged in bulk containers. The method according to the invention is characterized by mixing and grinding plastic waste containing: recycled low-density polyethylene (rLDPE) in an amount of 50 to 75 parts by weight and recycled linear low-density polyethylene (rLLDPE) in an amount of 25 to 50 parts by weight. At least one inorganic material selected from the group consisting of: talc, chalk, mica and zeolite is used as a filler in a total amount ranging from 30 to 60 parts by weight.

A method for producing PVC eco-agglomerate with uniform density and raw material composition throughout the cross-section is known from the Polish patent application no. PL413632A1, characterized in that it consists of the following successive stages: a) a stage of grinding the material to obtain a uniform grain size, wherein the grain size is 20 mm, b) a stage of gravity separation to separate light chips from heavy impurities (e.g. wooden elements), c) a stage of separating metal from the crushed chips using a magnetic field, wherein the magnetic field has an induction of not less than 0.28 [T] (2800 Gs), d) a stage of pelletizing (formation of an agglomerate under the influence of pressure and temperature), wherein the temperature is 170-190°C and the pressure is 50-200 MPa, e) a stage of removing pellets containing non-ferrous metals (aluminum, brass) using a non-ferrous metal separator.

A method for obtaining thermoplastic composites reinforced with short cellulose fibers is known from the Polish patent description No. PL234621B1, which consists in mixing a polymer matrix, short cellulose fibers and a compatibilizer, characterized in that in two composite granulates A and B the interphase of polymer matrix - cellulose fibers is modified using a compatibilizer or an anticompatibilizer, wherein the composite granulates A and B are obtained by melt mixing of the polymer matrix with cellulose fibers in a ratio of 70:30% by weight to 50:50% by weight, wherein in granulate A the compatibilizer is a polymer wax miscible with the matrix polymer in an amount of 0.5-3% by weight in relation to the matrix polymer, and in granulate B the anticompatibilizer is a polymer wax immiscible with the matrix polymer in an amount of 0.25-3% by weight of the matrix polymer. Granulates A and B are then melt-mixed in a ratio of 1:1 to 3:1 during further injection molding or extrusion processing, obtaining a composite with a differentiated fiber-matrix interface. Recycling processes for waste textiles, particularly mixtures of natural and synthetic textiles, leading to a material in a form suitable for industrial reuse are complex and difficult to implement, which poses a serious technical challenge. The method for obtaining granulate containing recyclate from textile waste according to the invention enables the production of a starting material suitable for industrial reuse in various sectors.

The essence of the method for obtaining granulate containing recyclate from textile waste according to the invention, which involves drying, segregation by properties, size fractionation, mixing, heating and cooling, and grinding, is characterized in that the textile waste material is transformed into a powder – textile recyclate – using cryogenic grinding. The resulting powder is then combined with: a) a polymeric material, or b) polymer recyclate, or c) a mixture of polymeric material and polymer recyclate (a+b), creating a mixture. After melting the mixture, a composite material is created, combining the selected thermoplastic with textile recyclate (textile powder), which is then transformed into a filament of a predetermined diameter. The resulting filament is cut into granules.

The method according to the invention in particular comprises the following processes:

a. drying the waste textile material, preferably vacuum drying; a step omitted in one version of the invention,

b. segregation of dry textile waste into two main fractions: the first fraction, where natural, plant-based materials such as cellulose and its derivatives, such as viscose, predominate, with synthetic textile fibers as an addition, wherein natural fibers constitute more than 51% of the weight share, and the second fraction, wherein synthetic materials such as polyesters, polyurethanes, polyamides predominate, with natural fibers as an addition, wherein synthetic fibers constitute more than 51% of the weight share; a step omitted in one version of the invention,

c. cutting, preferably with scissors, the waste textile material into strips of 1 to 5 mm thickness, preferably 1 mm,

d. freezing strips of waste textile material in tanks with liquid nitrogen,

e. cryogenic grinding of frozen strips of waste textile material into powder form,

f. drying the frozen and powdered textile waste until the temperature is equal to the ambient temperature,

g. fractionating the powdered and dry waste textile material according to grain size into a fraction with a grain size below 100 μm and into a fraction with a grain size above 100 μm; a step omitted in one version of the invention,

h. mechanical mixing of powdered textile waste material with: a) thermoplastic granulate, or b) recyclate granulate, i.e. polymer or composite material resulting from recycling, or c) a mixture of thermoplastic and composite (a+b),

i. melting and mixing the resulting mixture at a high temperature corresponding to the plasticity temperature of the thermoplastic,

j. forming a beam by forcing the molten mixture through a nozzle system,

k. cooling the resulting bundle and winding it onto a spool,

l. unwinding the resulting filament from the spool and cutting it using a scissors system into sections that form the target granulate.

As a thermoplastic in step h), one of the following is used: PMMA (polymethyl methacrylate), PC (polycarbonate), PLA (polylactide), PCL (polycaprolactone), ABS (acrylonitrile butadiene styrene terpolymer), PP (polypropylene), PE (polyethylene).

The method of obtaining granulate containing recyclate from textile waste according to the invention enables a wide use of the resulting granulate, among others, in injection molding machines, in the production of EPP (expanded polypropylene), nonwoven production technologies (e.g. melt-blown, spun-lace), shaped parts production technologies and 3D printing technologies using thermoplastics.

The subject of the invention is presented in the embodiment examples.

EXAMPLE 1

The method of obtaining granulate containing recyclate from textile waste according to the invention, where the processes of drying, segregation according to properties, size fractionation, mixing, heating and cooling, and grinding are carried out, is characterized in that the input textile waste material with a dominant (over 51%) share of components of natural origin (cotton) is subjected to the following successive stages:

a. vacuum drying for 2 to 24 hours,

b. scissor cutting into strips 1 to 5 mm thick, preferably 1 mm,

c. placing the strips in a grinding container and freezing for 20 to 60 minutes (preferably 60 minutes) at the temperature of liquid nitrogen,

d. cryogenic grinding to powder form - from 5 to 15 grinding cycles (preferably 10 cycles), where one cycle includes 5 minutes of grinding and 2 minutes of freezing,

e. drying until the temperature is equal to the ambient temperature, which includes: heating to a temperature of 50°C, drying at a reduced pressure compared to the atmospheric pressure for 1 to 2 hours (preferably 2 hours),

f. fractionation into a fraction with a grain size below 100 μm and into a fraction with a grain size above 100 μm using a shaker with a set of sieves, wherein the fraction above 100 μm is returned to the grinding process in order to minimize the generation of waste, g. mechanical mixing of the obtained cotton powder with polypropylene granulate (thermoplastic), wherein the share of cotton powder in relation to the share of polypropylene granulate is from 1:99 to 50:50 (preferably 20:80),

h. melting and mixing the resulting mixture at a high temperature corresponding to the plasticity temperature of the thermoplastic,

i. forming a cylindrical, rectangular or square cross-section bundle (filament) from the heated mixture by forcing it through a system of nozzles,

j. cooling the resulting bundle (filament) and winding it onto a spool,

k. unwinding the resulting filament from the spool and cutting it using a scissors system into sections that form the target granulate.

EXAMPLE 2

The method of obtaining granulate containing recyclate from textile waste according to the invention, where the processes of drying, segregation according to properties, size fractionation, mixing, heating and cooling, and grinding are carried out, is characterized in that the input textile waste material with a dominant (over 51%) share of components of artificial origin (viscose) is subjected to the following processes:

a. vacuum drying for 2 to 24 hours,

b. scissor cutting into strips 2 to 5 mm thick, preferably 2 mm,

c. placing the strips in a grinding container and freezing for 20 to 60 minutes (preferably 60 minutes) at the temperature of liquid nitrogen,

d. cryogenic grinding to powder form - from 5 to 15 grinding cycles (preferably 10 cycles), where one cycle includes 5 minutes of grinding and 2 minutes of freezing,

e. drying until the temperature is equal to the ambient temperature, which includes: heating to a temperature of 50°C, drying at a reduced pressure compared to the atmospheric pressure for 1 to 2 hours (preferably 2 hours),

f. fractionation into a fraction with a grain size below 100 μm and into a fraction with a grain size above 100 μm using a shaker with a set of sieves, wherein the fraction above 100 μm is returned to the grinding process in order to minimize the generation of waste, g. mechanical mixing of the obtained cotton powder with polypropylene recyclate (recycled material), wherein the share of cotton powder in relation to the share of polypropylene recyclate is from 1:99 to 50:50 (preferably 20:80),

h. melting and mixing the resulting mixture at a high temperature corresponding to the plasticity temperature of the thermoplastic,

i. forming a cylindrical, rectangular or square cross-section bundle (filament) from the heated mixture by forcing it through a system of nozzles,

j. cooling the resulting bundle (filament) and winding it onto a spool,

k. unwinding the resulting filament from the spool and cutting it using a scissors system into sections that form the target granulate.

Claims (2)

1. A method for obtaining granulate containing recyclate from textile waste, wherein the processes of drying, segregation based on properties, size fractionation, mixing, heating and cooling, and grinding are carried out, characterized in that the waste textile material is transformed into a powder - textile recyclate - using cryogenic grinding; the resulting powder is combined with: a) a polymeric material, or b) polymer recyclate, or c) a mixture of polymeric material and recyclate (a+b), forming a mixture from which, after melting, a composite material is obtained - thermoplastic + textile recyclate, which is transformed into a filament of a given diameter; the resulting filament is cut to form granulate; the method according to the invention in particular comprises the following steps: a. drying the waste textile material, preferably vacuum drying; a step omitted in one version of the invention, b. segregation of dry textile waste into two main fractions: the first fraction, where natural, plant-based materials such as cellulose and its derivatives, such as viscose, predominate, with synthetic textile fibers as an addition, with natural fibers constituting more than 51% of the weight share, and the second fraction, where synthetic materials such as polyesters, polyurethanes, polyamides predominate, with natural fibers as an addition, with synthetic fibers constituting more than 51% of the weight share; a step omitted in another version of the invention, c. cutting, preferably with scissors, the waste textile material into strips of 1 to 5 mm thickness, preferably 1 mm, d. freezing strips of waste textile material in tanks with liquid nitrogen, e. cryogenic grinding of frozen strips of waste textile material to powder form, f. drying the frozen and powdered textile waste until the temperature is equal to the ambient temperature, g. fractionating the powdered and dry textile waste material according to grain size into a fraction with a grain size below 100 gm and into a fraction with a grain size above 100 gm; a step omitted in yet another version of the invention, h. mechanical mixing of powdered textile waste material with: a) thermoplastic granulate, or b) recyclate granulate, i.e. polymer or composite material resulting from recycling, or c) a mixture of thermoplastic and composite (a+b), i. melting and mixing the resulting mixture at a high temperature corresponding to the plasticity temperature of the thermoplastic, j. forming a beam by forcing the molten mixture through a nozzle system, k. cooling the resulting bundle and winding it onto a spool, l. unwinding the resulting filament from the spool and cutting it using a scissors system into sections that form the target granulate. 2. A method according to claim 1, characterized in that one of the following is used as a thermoplastic in step h): PMMA (polymethyl methacrylate), PC (polycarbonate), PLA (polylactide), PCL (polycaprolactone), ABS (acrylonitrile-butadiene-styrene terpolymer), PP (polypropylene), PE (polyethylene).