CN116003875A

CN116003875A - Method for treating waste fabric containing polyester, spandex and dye

Info

Publication number: CN116003875A
Application number: CN202210171090.5A
Authority: CN
Inventors: 廖德超; 庄荣仁; 黄章鉴; 翁梓桓
Original assignee: Nan Ya Plastics Corp
Current assignee: Nan Ya Plastics Corp
Priority date: 2021-10-21
Filing date: 2022-02-22
Publication date: 2023-04-25

Abstract

The invention provides a method for treating waste dye fabrics containing polyester, spandex and the like, which comprises the following steps. Step a: waste fabrics containing polyester, spandex, and dye are provided. Step b: the waste fabric is subjected to a first stage treatment including elution to obtain a first liquid and a first solid. The first stage treatment involves elution by means of a co-solvent mixed with an oxidizing agent. The first solids comprise recycled polyester and/or the first liquid comprises recycled spandex or degraded spandex.

Description

Method for treating waste fabric containing polyester, spandex and dye

Technical Field

The present invention relates to a method for treating waste fabrics, and more particularly, to a method for treating waste fabrics containing polyester, spandex and dye.

Background

Polyester fiber fabrics or spandex fiber fabrics are very widely used in the market or in life. For example, the polyester fibers may be co-woven with spandex fibers and then used in the textile industry or in the garment industry to create a wide variety of fabrics such as caps, garments, pants, skirts, socks, and the like. Therefore, how to recover and/or treat polyester-containing waste from these co-fabrics, such as polyester and/or spandex, has been the subject of current research.

Disclosure of Invention

The invention aims at a method for treating waste fabrics containing polyester, spandex and dye, which can reduce the overall use amount of cosolvent and/or improve the recovery amount or quality of polyester and/or spandex.

According to an embodiment of the present invention, a method for treating waste fabrics containing polyester, spandex and dye includes the following steps. Step a: waste fabrics containing polyester, spandex, and dye are provided. Step b: the waste fabric is subjected to a first stage treatment including elution to obtain a first liquid and a first solid. The first stage treatment involves elution by means of a co-solvent mixed with an oxidizing agent. The first solids comprise recycled polyester and/or the first liquid comprises recycled spandex or degraded spandex.

The invention can improve the decoloring function of the oxidant under the cosolvent environment, including the physical removal of dye from the fiber and the removal of chromophore, and improves the hue quality of the recovered fiber so as to improve the economic value of recovery and reuse.

Based on the above, by the steps, the method for treating the waste fabric containing polyester, spandex and dye can reduce the total use amount of the cosolvent and/or improve the recovery amount or quality of the spandex and/or the polyester.

Drawings

Fig. 1 is a schematic partial flow diagram of a method for treating waste containing polyester and spandex according to an embodiment of the invention.

Detailed Description

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

In the following detailed description, for purposes of explanation and not limitation, example embodiments disclosing specific details are set forth in order to provide a thorough understanding of the various principles of the present invention. However, it will be apparent to one having ordinary skill in the art having had the benefit of the present disclosure, that the present invention may be practiced in other embodiments that depart from the specific details disclosed herein. In addition, descriptions of well-known devices, methods and materials may be omitted so as to not obscure the description of the various principles of the present invention.

Ranges may be expressed herein as from "about" one particular value to "about" another particular value, as well as directly to one particular value and/or to another particular value. When the range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are obviously related to the other endpoint or independent of the other endpoint.

Non-limiting terms (such as may, for example, or other like terms) are used herein in a non-essential or alternative manner, including, adding or otherwise.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[ recycle ]

A recycle containing polyester (polyester), spandex (spandex) and dye is provided.

In one embodiment, the recovery method includes: collecting various types of recycled materials or waste containing spandex and polyester; the corresponding classification may be performed according to the type, color and/or use of the recycled material. The aforementioned recyclates may include, for example, clothing, but the present invention is not limited thereto. The fibrous components used are noted on a generally regular clothing label.

In one embodiment, the recycle containing spandex and polyester may be further subjected to one of the following pretreatment (i.e., treatment prior to subsequent treatment; still essentially recycle): removing objects (e.g., clips, fasteners, ornaments, labels, and/or other objects that are not significantly spandex or polyester-containing) from the recycle; preliminary cleaning of the recovered material (e.g., washing the soil with water, throwing away impurities, etc., but not limited thereto); the single size of the recycled material is reduced by physical means (such as shearing, cutting or cutting, but not limited to); and/or drying the recovered product.

In one embodiment, the recovery method may also include: by directly purchasing the treated recycle containing spandex and polyester (e.g., recycle duvet, but not limited to).

It is noted that the term "spandex" as used herein includes polymers commonly referred to as spandex or polyurethane elastic fibers (Polyurethane elastomeric fibre). For fabric applications, common trade names for inclusion of spandex polymers include, for example, acepora, creora, dorlastan (Dorlastan), elaspan, ESPA, INVIYA, linel, lycra/lecra (Lycra), nylon (Neolon), ROICA, and the like. Spandex can be formed by chain extension (chain extension reaction) of a prepolymer and a diamine. In the aforementioned chain extension reaction, the solvent used is usually Dimethylformamide (DMF) or dimethylacetamide (DMAc). The spandex may comprise polyester spandex or polyether spandex. In this context, polyester spandex is meant in particular. In the chain extension reaction for forming the polyester urethane elastic fiber, the prepolymer used may be formed by a mixed reaction of glycol (e.g., ethylene Glycol (EG)) and diisocyanate monomer (diisocyanate monomer).

It is noted that the term "polyester" herein includes polymers commonly referred to as polyesters, particularly aromatic polyesters, and herein particularly polyesters derived from terephthalic acid (purified terephthalic acid; PTA) and Ethylene Glycol (EG) (i.e., polyethylene terephthalate (polyethylene terephthalate; PET)).

In addition, the polyesters herein may also be, for example, poly (trimethylene terephthalate), poly (tetramethylene terephthalate), poly (ethylene naphthalate), or combinations of the foregoing. In this embodiment, the polyester is preferably polyethylene terephthalate, polypropylene terephthalate, or a combination thereof. In addition, a copolymer, which particularly means a copolymer obtainable by using two or more dicarboxylic acids and/or two or more diol components, may also be used.

In one embodiment, the dye used in the fabric is mostly an organic dye. For example, azo dyes such as monoazo dyes (monoazo dyes) or disazo dyes (disazo dyes) are often used for dyeing spandex or polyester. The adhesion of organic dyes to polymers is generally better. It is noted that the present invention is not limited to the kind of organic dye.

In one embodiment, the dye for the fabric does not comprise an inorganic dye. Most inorganic dyes contain heavy metal elements, and can easily cause allergy or discomfort of human bodies.

[ first stage Process ]

The recovered material is subjected to a first stage treatment to obtain a first liquid material and a first solid material.

It should be noted that the term "liquid" in this specification is not limited to the fact that the substance is completely liquid. For example, "liquid" may include a liquid; and a suspension suspended in or on the liquid. The particle size of the aforementioned suspension may be less than or equal to 1 millimeter (mm); alternatively, the foregoing suspension may pass through a mesh having a mesh number (mesh) of 18 or greater, as per ASTM E11-01. Also for example, "liquid" may include polymer solutions (polymer colloids) or other similar colloids.

It should be noted that the term "solid" is not limited to the fact that the solid is completely solid. For example, "solids" may include solids; and a liquid attached to the solid or located between two of the solids by capillary phenomenon. The "solids" may be dried by suitable means (e.g., heat drying and/or reduced pressure drying) to obtain the solids with little or no liquid. The weight of the solids after drying may be about 80% or more based on the total weight of the "solids"; preferably about 90% or more; more preferably about 95% or more.

In this embodiment, the first stage treatment may include immersing the recovered material in a mixed solution of an organic solvent and water (hereinafter referred to as "cosolvent") (which may be referred to as "elution"). For example, the aforementioned recyclates may be immersed in a co-solvent mixed with an oxidizing agent; alternatively, the above-mentioned recovered material is immersed in a cosolvent, and then an oxidizing agent is mixed therein. The first liquid and the first solid may then be separated from each other by any suitable means, such as, but not limited to, filtering with a screen.

In one embodiment, the weight ratio of the recycle to the co-solvent mixed with the oxidant (i.e., the weight of the recycle to the weight of the co-solvent mixed with the oxidant) in the first stage treatment may be about 1:8 to about 1:30. Preferably, in the first stage treatment, the weight ratio of recycle to co-solvent mixed with oxidant may be about 1:10 to about 1:15.

In one embodiment, the first stage process may be performed by leaching the recycle into a co-solvent mixed with an oxidant and heating to a temperature of about 80 ℃ to 160 ℃. Preferably, the heating may be to about 90℃to 150℃at a temperature above the glass transition temperature of the polyester. If the heating temperature is too low (e.g., less than 80 ℃), the productivity may be poor due to too slow reaction. If the heating temperature is too high (e.g., greater than 160 ℃), the organic dye may be degraded or decolorized poorly (e.g., too much oxidant produces self-redox reactions), and/or there may be a worker's concern.

In one embodiment, the first stage treatment may be a solvent wash in which the recovery is immersed in a co-solvent mixed with the oxidant, stirred and/or allowed to stand for more than about 1 hour. Preferably, stirring and/or standing is carried out for about 1 to 9 hours. More preferably, stirring and/or standing is performed for more than about 2 hours. Still more preferably, stirring and/or standing is carried out for about 2 hours to 8 hours.

In one embodiment, the first stage process may be performed by immersing the recycle in a co-solvent mixed with an oxidant and heating (the heating temperature may be as described above); and stirred and/or allowed to stand during heating (stirring and/or standing time may be as described above).

In one embodiment, the elution of the first stage treatment may be performed by a mixture of an amide solvent and water.

In one embodiment, the preferred amide solvent may include dimethylformamide, dimethylacetamide, or a combination thereof, one of which may be: dimethylacetamide or dimethylformamide are more commonly used as solvents in the reaction for synthesizing spandex.

In one embodiment, a more suitable amide solvent is dimethylformamide. At the same amount used, dimethylformamide may be better soluble in spandex than dimethylacetamide.

In one embodiment, the concentration of the organic solvent in the co-solvent mixed with the oxidizing agent is about 20wt% (weight percent) to about 95wt% based on the total of the co-solvent mixed with the oxidizing agent. Preferably, the concentration of the organic solvent is about 30wt% to about 90wt% based on the total of the co-solvents mixed with the oxidizing agent.

For example, the concentration of dimethylformamide is about 20wt% to about 95wt% based on the total of dimethylformamide/water co-solvent mixed with the oxidizing agent. Preferably, the concentration of dimethylformamide is about 30wt% to about 90wt% based on the total of the dimethylformamide/water co-solvent mixed with the oxidizing agent.

In one embodiment, in the first stage of the process, the oxidizing agent used is an inorganic oxidizing agent. Inorganic oxidizing agents may include hydrogen peroxide (hydrogen peroxide), chlorates (e.g., sodium or calcium chlorate), hypochlorites (e.g., calcium hypochlorite (calcium hypochlorite) or sodium hypochlorite (sodium hypochlorite)), perchlorates, ozone, nitric acid, nitrates, perborates (e.g., sodium perborate), permanganates (e.g., potassium permanganate (potassium permanganate)), dichromates (e.g., sodium dichromate), or combinations thereof.

In one embodiment, in the acid treatment of the first stage treatment, the inorganic oxidizing agent used comprises hydrogen peroxide, hypochlorite or ozone. The reduction product of hydrogen peroxide is typically water, oxygen or hydroxyl (hydroxide). The hypochlorite reduction product may typically be chloride. The ozone reduction product may typically be oxygen. Hydrogen peroxide, hypochlorite or ozone is easier to use and/or treat (e.g., waste or exhaust treatment, but not limited to).

In one embodiment, the oxidizing agent is adapted to oxidize the organic dye, which may decompose or decolorize it. Therefore, the cosolvent containing the oxidant can have the effects of separation and decolorization on the polyester-spandex blended fabric containing the dye. That is, compared with the method of dissolving or degrading spandex with a solvent without an oxidizing agent, and then removing dye for color removal (e.g., using an oxidizing agent) after separating polyester-spandex, the method of this embodiment or the like can further improve the recycling quality of polyester and spandex, and can further improve the recycling value.

In one embodiment, the concentration of the oxidant in the co-solvent mixed with the oxidant is about 0.5wt% to about 10wt% based on the total co-solvent mixed with the oxidant. Preferably, the concentration of the oxidizing agent is about 1wt% to about 8wt% based on the total co-solvent mixed with the oxidizing agent. If the concentration of the oxidizing agent is too low (e.g., less than 0.5 wt%), the organic dye may be decomposed or decolorized poorly. If the concentration of the oxidizing agent is too high (e.g., greater than 10 wt%), there may be a worker's safety concern.

In one embodiment, the oxidizing agent may decompose the organic dye such that it does not have the original color (i.e., discolors).

In one embodiment, the oxidizing agent may cause a portion of the functional groups of the organic dye to be altered, thereby making it easier to detach (i.e., decolorize) from other polymers (i.e., polyester or spandex).

In one embodiment, the decomposed or structurally modified organic dye may be more easily dissolved in the solvent by the treatment of the oxidizing agent. For example, the decomposed or structurally modified organic dye may be more easily dissolved in water or an organic solvent.

In one embodiment, the first solid may include other polymers other than spandex (e.g., polyester). It is noted that the invention does not exclude that small amounts of spandex are also included in the first solids.

In one embodiment, the first liquid may include a co-solvent and spandex/degraded spandex, spandex suspension, or degraded spandex suspension dissolved in the co-solvent. It is noted that the invention does not exclude that the first liquid material also comprises a small amount of a polymer other than spandex.

In one embodiment, the first liquid may not contain an oxidizing agent. For example, hydrogen peroxide may be decomposed into water and oxygen after heating. For another example, hydrogen peroxide that has not reacted with the dye may be decomposed into water and oxygen after heating.

In one embodiment, the amount of spandex in the first liquid is about 75wt% to about 90wt% and the amount of spandex in the first solid is correspondingly about 25wt% to about 10wt% based on the total amount of spandex in the recycle.

In one embodiment, the recovery or quality of spandex and/or polyester can be improved by the co-solvent mixed with the oxidant.

In one embodiment, the color of the recycled polyester may be near white. As indicated by a chromaticity diagram (CIE 1931color space) defined by the international commission on illumination (International Commission on Illumination; CIE), if the color brightness (i.e., L) of the recycled material comprising polyester, spandex and dye is about 20, the color brightness of the polyester recycled by the above method may be about 75 or more, the a may be about-4 to +4, and the b may be about-8 to +8.

In one embodiment, the whiteness is improved to improve the utilization value of recycled materials (such as recycled spandex and/or recycled polyester).

[ second stage treatment ]

In one embodiment, the first liquid material may be subjected to a second stage treatment to obtain a second liquid material and a second solid material.

In one embodiment, the second stage treatment may include dilution. For example, the non-organic solvent (e.g., water) used in the first stage of the above-described process may be added to the first liquid, and then the second liquid and the second solid may be separated from each other by a suitable means (e.g., filtering with a screen or standing separation; but not limited to).

In one embodiment, the second stage treatment may further include cooling the solution (e.g., cooling to room temperature (about 25 ℃) or cooling to below room temperature and above the freezing point) after adding the non-organic solvent to the first liquid material, but the invention is not limited thereto.

In one embodiment, the second stage treatment may further include stirring and/or standing the solution (e.g. stirring for 3 minutes and standing for 30 minutes or more, or stirring for 5 minutes and standing for 60 minutes or more) after adding the non-organic solvent to the first liquid material, but the invention is not limited thereto.

In one embodiment, the first stage treatment may include a first stage treatment by solvent elution with a dimethylformamide/water co-solvent containing an oxidizing agent and containing 20wt% to 95wt% dimethylformamide, and the second stage treatment may include adding water to the first liquid as described above to reduce the concentration of dimethylformamide in the solution to less than about 20 wt%.

In one embodiment, the second solid may comprise spandex.

In one embodiment, the second liquid may include a co-solvent and spandex/degraded spandex, spandex suspension, or degraded spandex suspension dissolved in the co-solvent. The concentration of the organic solvent in the second liquid material is less than the concentration of the organic solvent in the first liquid material.

In one embodiment, the second liquid may not contain an oxidizing agent.

[ third stage Process ]

In an embodiment, the first solid may be subjected to a third stage treatment to obtain a third liquid and a third solid.

In one embodiment, the third stage treatment may include elution. In one embodiment, the third stage process may be similar to the first stage process. For example, the first solid may be immersed in the co-solvent, and then the third liquid and the third solid may be separated from each other by a suitable means (e.g., screen filtration; but not limited to).

In one embodiment, the third stage of the process may be performed by immersing the first solid in the co-solvent and heating (e.g., to about 70.+ -. 5 ℃ C. To about 100.+ -. 5 ℃ C.), but the invention is not limited thereto.

In one embodiment, the third stage of the process may be performed by immersing the first solid in the co-solvent and stirring and/or standing (e.g., stirring and/or standing for 30 minutes or more, or stirring and/or standing for 60 minutes or more), but the invention is not limited thereto.

In one embodiment, the organic solvent used for the elution of the third stage treatment may be the same as or similar to the organic solvent used for the elution of the first stage treatment.

In one embodiment, the concentration of the organic solvent in the dissolved co-solvent of the third stage treatment is different from the concentration of the organic solvent in the dissolved co-solvent of the first stage treatment; and the concentration of the organic solvent in the dissolved co-solvent of the third stage treatment is different from the concentration of the organic solvent in the second liquid.

In one embodiment, the concentration of the organic solvent in the dissolved co-solvent of the third stage treatment is less than the concentration of the organic solvent in the dissolved co-solvent of the first stage treatment; and the concentration of the organic solvent in the dissolved cosolvent of the third stage treatment is greater than the concentration of the organic solvent in the second liquid.

In one embodiment, the concentration of the oxidizing agent in the solution used in the elution of the third stage treatment may be less than 0.5wt%. In one embodiment, the solution used for the elution of the third stage treatment may be free of oxidizing agent.

In one embodiment, dimethylformamide having a purity of 99wt% or more may be first mixed with a recovered dimethylformamide/water co-solvent having a concentration of about 20% or less, and then the above mixture may be used as a solvent for the third stage treatment. Thus, the overall usage amount of dimethylformamide can be reduced. In one embodiment, the concentration of dimethylformamide in the aforementioned mixture may be greater than 80wt%. Therefore, the polyurethane fiber dissolving agent has a better dissolving effect on polyurethane fibers.

In one embodiment, the recovered dimethylformamide/water cosolvent may include a second liquid obtained after the second stage treatment (including the second liquid obtained in the present treatment cycle; and/or the second liquid obtained in the previous treatment cycle under the multiple times of the method of the present invention); and/or by a fourth liquid obtained after a fourth stage of treatment (as described in more detail later) carried out in a previous treatment cycle (under the process of the invention). In this way, the whole usage amount of the dimethylformamide can be reduced, and the recovered dimethylformamide/water cosolvent (such as the second liquid material and/or the fourth liquid material) can be dissolved in the cosolvent to further recover the spandex/the degraded spandex, the spandex suspension or the degraded spandex suspension, so that the recovery amount of the spandex can be improved.

For example, the method of treating waste fabric containing polyester, spandex and dye may include the following steps. Step a: waste fabrics containing polyester, spandex, and dye are provided. Step b: the waste fabric is subjected to a first stage treatment including elution to obtain a first liquid and a first solid. Step c: and performing a second stage treatment on the first liquid material to obtain a second liquid material and a second solid material. Step d: the first solid is subjected to a third stage treatment to obtain at least a third liquid. In the multiple processing processes, the step a, the step b and the step d can be executed N times, wherein N is greater than or equal to 1; step c is performed M times, wherein M is less than or equal to N; and the elution of the nth third stage treatment includes elution by the mth second liquid.

Also for example, the method of treating waste fabric containing polyester, spandex and dye may include the following steps. Step a: waste fabrics containing polyester, spandex, and dye are provided. Step b: the waste fabric is subjected to a first stage treatment including elution to obtain a first liquid and a first solid. Step c: and performing a second stage treatment on the first liquid material to obtain a second liquid material and a second solid material. Step d: the first solid is subjected to a third stage treatment to obtain at least a third liquid. Step e: the third liquid material is subjected to a fourth stage treatment (described later) to obtain a fourth liquid material and a fourth solid material. In the multiple processing processes, the steps a, b, d and e can be performed N times, where N is greater than or equal to 2; the elution of the nth third stage treatment includes eluting with a fourth liquid of the nth time, wherein P is less than N.

In one embodiment, the third solid may include other polymers other than spandex (e.g., polyester). It is noted that the present invention does not exclude that the third solid also includes a very small amount of spandex.

In one embodiment, the proportion of spandex in the third solid (which may be the weight ratio of spandex to the total weight of the third solid) is less than the proportion of spandex in the first solid (which may be the weight ratio of spandex to the total weight of the first solid).

In one embodiment, the proportion of polyester in the third solid (which may be the weight ratio of polyester to the total weight of the third solid) is greater than the proportion of polyester in the first solid (which may be the weight ratio of polyester to the total weight of the first solid).

In one embodiment, the third liquid may include a co-solvent and spandex/degraded spandex, spandex suspension, or degraded spandex suspension dissolved in the co-solvent.

In an embodiment, the amount of spandex in the third liquid may be about 90wt% or more based on the total amount of spandex in the first solid; or more 95wt% or more. That is, by means of two-stage elution (i.e., the first stage and the third stage), the spandex in the recovered product can be almost dissolved or degraded to be separated in the subsequent steps.

[ fourth stage Process ]

In one embodiment, the third liquid material may be subjected to a fourth stage treatment to obtain a fourth solid material and a fourth liquid material.

In one embodiment, the fourth stage process may include dilution. For example, the non-organic solvent used in the first stage treatment or the third stage treatment may be added to the third liquid material, and then the fourth liquid material and the fourth solid material may be separated from each other by a suitable means (e.g., filtering with a screen or standing separation; but not limited to).

In one embodiment, the fourth stage may further comprise cooling the solution (e.g. to room temperature (about 25 ℃) or below room temperature and above freezing point) after adding the solvent to the third liquid material, but the invention is not limited thereto.

In one embodiment, the fourth stage may further include stirring and/or standing the solution (e.g., stirring for 3 minutes or more and standing for 30 minutes or stirring for 5 minutes or more and standing for 60 minutes or more) after adding the non-organic solvent to the third liquid material, but the present invention is not limited thereto.

In one embodiment, the first stage treatment may comprise a first stage treatment of the solvent with an oxidizing agent and a dimethylformamide/water co-solvent containing 20wt% to 95wt% dimethylformamide, the third stage treatment may comprise a third stage treatment of the solvent with two stages of different concentrations of dimethylformamide/water co-solvent, and the fourth stage treatment may comprise adding water to the third liquid as described above to reduce the concentration of dimethylformamide in the solution to less than about 20%.

In one embodiment, the fourth solid may comprise spandex.

In one embodiment, the fourth liquid may include a co-solvent and spandex/degraded spandex, spandex suspension, or degraded spandex suspension dissolved in the co-solvent. The concentration of the organic solvent in the fourth liquid material is less than the concentration of the organic solvent in the third liquid material.

[ Recycling of Spandex ]

The second solids and/or the fourth solids, including spandex, may be substantially recycled by any suitable means (e.g., but not limited to, spandex drawing or spandex granulation).

In one embodiment, the second solid and/or the fourth solid may be further washed to reduce the concentration of the organic solvent or other substances (e.g., decomposed or structurally modified organic dye or decomposed or non-decomposed oxidizer; but not limited thereto) in the second solid and/or the fourth solid.

In one embodiment, the second solid and/or the fourth solid may be dried, but the present invention is not limited thereto.

[ Recycling of polyester ]

The third solid comprising polyester may basically be recycled by any suitable means (e.g., but not limited to, granulation of polyester).

In one embodiment, the first solid and/or the third solid may be further washed to reduce the concentration of the organic solvent or other substances (e.g., decomposed or structurally modified organic dye or decomposed or non-decomposed oxidizer; but not limited thereto) in the first solid and/or the third solid.

In one embodiment, the first solid and/or the third solid may be dried, but the present invention is not limited thereto.

Examples and comparative examples

The present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited at all by the examples.

EXAMPLE 1

The first stage is to take 20g (g) of Polyester (PET) -spandex (spandex) blended waste fabric (L=27%, PET weight is 80% and spandex weight is 20%), place the waste fabric into a 1 liter (liter; L) reaction tank, and place 100g of water, 400g of dimethylformamide and 1.5g of sodium hypochlorite. Stirring was carried out at 120℃for 6 hours, the spandex had dissolved and the PET retained the fiber structure. The temperature was reduced to 40℃and PET (i.e., first solids) was separated from the spandex slurry (i.e., first liquid) by passing through a 3 millimeter (millimeter; mm) screen.

The second stage treatment is to separate the spandex from the co-solvent with a 10 micron (μm) screen and wash the spandex powder (i.e., second solids) with 8g of water. The co-solvent separated by the 10 μm sieve and the water used for washing may be collected (i.e., the second liquid).

The third stage treatment is that the PET fibers (i.e. the first solids) are placed on a 3mm screen, washed with the second liquid and then washed with 32g of water. The cleaned PET fibers may be collected (i.e., third solids). The second liquid material after washing and the water after washing may be collected (i.e., the third liquid material).

A fourth stage of treatment, namely separating spandex and cosolvent from the third liquid material by a 1 μm filter screen to obtain a fourth solid material and a fourth liquid material

Drying the PET fiber (namely, the third solid matter) for 2 hours at 105 ℃ to obtain the PET fabric with the purity weight ratio of 99.7%; l=84%, a=0.9, b=5.7, facilitating recycling applications.

The measurement mode of the purity weight ratio of PET is as follows: an Erlenmeyer flask having a volume of 1000 cubic centimeters (cc) was taken, 600cc of a 75% strength by weight aqueous sulfuric acid solution was poured, 3g of the separated PET fabric sample was put into the flask, and the flask was heated to 50.+ -. 5 ℃ for 1 hour and shaken 1 time every 10 minutes. Pouring 200cc of sulfuric acid aqueous solution with the concentration of 75% by weight into a funnel to clean the fabric, pumping air and draining liquid, and pouring 200cc of clean water into the funnel to clean the fabric for 2 times; the liquid is pumped out each time. Then, the treated PET fabric was dried in an oven at 105℃for 2 hours and weighed to 2.986g, and the purity to weight ratio was confirmed to be 99.5%. This method is adopted in the following other examples and comparative examples, and thus will not be described in detail.

EXAMPLE 2

The steps or modes are similar to those of the example 1, and only dimethylacetamide is used for replacing dimethylformamide, so that the purity weight ratio of the PET fabric is 99.3%; l=81%, a=1.4, b=6.9, facilitating recycling applications.

EXAMPLE 3

The steps or modes are similar to those of example 1, and only calcium hypochlorite is used for replacing sodium hypochlorite, so that the purity weight ratio of the PET fabric is 99.6%; l=85%, a=0.9, b=3.4, facilitating recycling applications.

Comparative example 1

Similar to the first stage process: 20g (L=27%, 80% of PET and 20% of spandex) of PET-spandex blended waste fabric is taken, placed in a 1L reaction tank, 100g of water and 400g of dimethylformamide are placed in the reaction tank, stirred for 6 hours at the temperature of 110 ℃, the spandex is dissolved, and the PET retains the fiber structure. Cooling to 40 ℃, and separating PET (similar to first solid matters; abbreviated as first solid matters) from spandex slurry (similar to first liquid matters; abbreviated as first liquid matters) through a screen with the diameter of 3 mm.

Similar to the second stage process: the spandex slurry (i.e., first-like liquid) was separated from the co-solvent with a 10 μm sieve, and the spandex powder (i.e., second-like solid; abbreviated as second-like solid) was washed with 8g of water. The co-solvent separated by the 10 μm sieve and the water used for washing can be collected (i.e., similar to the second liquid; abbreviated as "second liquid").

Similar to the third stage process: the PET fibers (i.e., first-like solids) were placed on a 3mm screen, washed with a second-like liquid, and the PET fibers (i.e., third-like solids; abbreviated as third-like solids) were washed with 32g of water. The second liquid-like material used after the washing and the water used after the washing can be collected (i.e., similar to the third liquid-like material; simply referred to as the third liquid-like material).

Similar to the fourth stage process: separating spandex from cosolvent with 1 μm sieve to obtain solid similar to fourth solid (called fourth solid for short) and liquid similar to fourth liquid (called fourth liquid for short).

Drying the PET fiber (namely, similar third solid matter) for 2 hours at 105 ℃ to obtain the PET fabric with the purity weight ratio of 99.4%; l=57%, a=2.2, b=9.4. The PET fiber is gray yellow, and can be recycled by decoloring.

[ practicality ]

By the method, the spandex or the polyester in the recycled material can be recycled. And the recovered spandex or polyester can be reused. The manner of reuse is for example but not limited to: for producing spandex-containing articles such as fabrics, curtains, tires, etc. The treatment method for recycling the polyester comprises physical remanufacturing or chemical remanufacturing. Physical remanufacturing comprises melting the treated polyester by an extruder, and then extruding and granulating. The chemical remanufacturing comprises depolymerizing the recovered polyester by utilizing a chemical depolymerization solution, repolymerizing the monomer and/or oligomer obtained after depolymerization under specific conditions, and then granulating; the chemical depolymerization liquid may be water, methanol, ethanol, ethylene glycol, diethylene glycol, or any combination. The treatment of the recovered polyester may be referred to as taiwan patent application No. 110113065 and/or chinese invention patent application No. 202110825541.8.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A method for treating waste fabrics containing polyester and spandex, comprising the steps of:

step a: providing a waste fabric comprising polyester, spandex and dye; and

step b: performing a first stage treatment on the waste fabric to obtain a first liquid and a first solid, wherein:

the first stage treatment comprises elution by means of a co-solvent mixed with an oxidizing agent; and is also provided with

The first solids comprise recycled polyester and/or the first liquid comprises recycled spandex or degraded spandex.

2. The method for treating waste fabrics containing polyester and spandex according to claim 1, wherein a cosolvent comprising an amide solvent and water is used in the first-stage treatment.

3. The method for treating waste fabrics containing polyester and spandex according to claim 2, wherein the organic solvent used in the co-solvent comprises only dimethylformamide or dimethylacetamide.

4. The method of claim 1, wherein the oxidizing agent is an inorganic oxidizing agent comprising hydrogen peroxide, permanganate, ozone, nitric acid, nitrate, chlorate, perchlorate, hypochlorite, perborate, dichromate, or a combination thereof.

5. The method for treating waste fabrics containing polyester and spandex according to claim 1, wherein the concentration of the organic solvent in the co-solvent used in the elution of the first-stage treatment is 20 to 95wt%.

6. The method of treating waste fabrics containing polyester and spandex according to claim 1, wherein the concentration of the oxidizing agent used in the elution of the first-stage treatment is 0.5 to 10wt%.

7. The method of treating waste fabrics containing polyester and spandex according to claim 1, wherein the acid treatment is performed at a temperature higher than the glass transition temperature of polyester.

8. The method of claim 1, wherein the first stage treatment is performed by a solvent which further comprises heating to 80 ℃ to 150 ℃.

9. The method of treating waste fabrics containing polyester and spandex according to claim 1, wherein in the step b, the weight ratio of the waste fabrics to the co-solvent mixed with the oxidizer is 1:8 to 1:30.

10. The method of treating waste fabrics containing polyester and spandex according to claim 1, wherein the treatment time of the first stage treatment is 1 to 9 hours.

11. The method for treating waste fabrics containing polyester and spandex according to claim 1, further comprising:

step c: performing second-stage treatment on the first liquid material to obtain a second liquid material and a second solid material;

step d: performing a third stage treatment on the first solid to obtain at least a third liquid; and

step e: performing a fourth stage treatment on the third solid to obtain a fourth liquid and a fourth solid, wherein:

the concentration of the organic solvent in the second liquid material is less than the concentration of the organic solvent in the first liquid material;

the third stage treatment comprises elution;

the concentration of the organic solvent in the fourth liquid material is less than the concentration of the organic solvent in the third liquid material; and is also provided with

The third solid comprises recycled polyester and/or the second solid and/or the fourth solid comprises recycled spandex.

12. The method of claim 1, wherein the recycled polyester has an L value of 75% or more, a is from-4 to +4, and b is from-8 to +8.