Method for treating waste fabrics containing polyester and nylon

Abstract

The present invention provides a method for treating waste fabrics containing polyester and nylon, which comprises the following steps. Step a: providing waste fabrics containing polyester and nylon. Step b: performing a first stage treatment including acid treatment on the waste fabric to obtain a first liquid and a first solid. Step c: performing a second stage treatment on the first liquid to obtain a second liquid and a second solid. Step d: performing a third stage treatment including acid treatment on the first solid to obtain a third liquid. Step e: performing a fourth stage treatment on the third liquid to obtain a fourth liquid and a fourth solid. The acid concentration of the second liquid is less than that of the first liquid. The acid concentration of the fourth liquid is less than that of the third liquid.

Description

Technical Field

[0001] The invention relates to a method for treating waste fabrics, in particular to a method for treating waste fabrics containing polyester and nylon. Background Art

[0002] Polyester fiber fabrics or nylon fiber fabrics are widely used in the market or in daily life. For example, polyester fiber can be co-woven with nylon fiber, and then through the common methods in the textile industry or garment industry, a variety of hats, clothes, pants, skirts, socks and other fabrics can be made. Therefore, with the rising awareness of environmental protection today, how to recycle the polyester and / or nylon in these co-woven fabrics and / or treat the waste containing polyester has become a current research topic. Summary of the invention

[0003] The present invention is directed to a method for treating waste fabrics containing polyester and nylon, which can reduce the overall usage of acid and / or increase the recovery of polyester and / or nylon.

[0004] According to an embodiment of the present invention, a method for treating waste fabrics containing polyester and nylon includes the following steps. Step a: providing waste fabrics containing polyester and nylon. Step b: performing a first stage treatment on the waste fabric to obtain a first liquid and a first solid. Step c: performing a second stage treatment on the first liquid to obtain a second liquid and a second solid. Step d: performing a third stage treatment on the first solid to obtain at least a third liquid. Step e: performing a fourth stage treatment on the third liquid to obtain a fourth liquid and a fourth solid. The first stage treatment includes an acid treatment. The acid concentration of the second liquid is less than that of the first liquid. The third stage treatment includes an acid treatment. The acid concentration of the fourth liquid is less than that of the third liquid. The third solid contains recycled polyester, and / or the second solid and / or the fourth solid contain recycled nylon.

[0005] Based on the above, through the above steps, the method for treating waste fabrics containing polyester and nylon of the present invention can reduce the overall usage of acid solution and / or increase the recovery amount of nylon and / or polyester. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a partial flow diagram of a method for treating waste containing polyester and nylon according to an embodiment of the present invention. DETAILED DESCRIPTION

[0007] In the following detailed description, for the purpose of illustration and not limitation, exemplary embodiments that disclose specific details are set forth to provide a thorough understanding of the various principles of the present invention. However, it will be apparent to one of ordinary skill in the art that, with the benefit of this disclosure, 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 to avoid obscuring the description of the various principles of the present invention.

[0008] Ranges may be expressed herein as from "about" one particular value to "about" another particular value, which may also be expressed directly as one particular value and / or to another particular value. When expressing the range, another embodiment includes from the one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation via the 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 range may be clearly related to or independent of the other endpoint.

[0009] In this document, non-limiting terms (such as: may, can, for example or other similar terms) mean that implementation, inclusion, addition or existence are optional or necessary.

[0010] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It will also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the relevant technical context and should not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0011] [Recyclables]

[0012] Provide recycled materials containing polyester and nylon.

[0013] In one embodiment, the method of obtaining recyclables includes, for example, collecting various types of recyclables or waste containing nylon; and classifying the recyclables according to their types, colors, and / or uses. The recyclables may include clothing, for example, but the present invention is not limited thereto. Generally, regular clothing labels will indicate the fiber composition used.

[0014] In one embodiment, the recyclables containing nylon may be further subjected to one of the following pre-treatments (i.e., treatment before subsequent treatment; still recyclables in essence): removing objects on the recyclables (e.g., clips, fasteners, accessories, labels and / or other objects that are obviously not nylon-containing); performing preliminary cleaning on the recyclables (e.g., washing stains, shaking off impurities, etc., but not limited to); reducing the single size of the recyclables by physical means (e.g., shearing, cutting, or slicing, but not limited to); and / or drying the recyclables.

[0015] In one embodiment, the method of obtaining the recyclables may also include, for example, directly purchasing the processed recyclables containing nylon.

[0016] It should be noted that the term "nylon" in this article includes polymers commonly referred to as nylon, such as: Nylon 66, Nylon 6, Nylon 510, Nylon 1,6, other similar polymers including polyamide functional groups and similar to the aforementioned polymers, the aforementioned copolymers or the aforementioned co-woven fabrics.

[0017] It should be noted that the term "polyester" herein includes polymers commonly referred to as polyesters, particularly aromatic polyesters, and particularly refers to polyesters derived from purified terephthalic acid (PTA) and ethylene glycol (EG) (i.e., polyethylene terephthalate (PET)).

[0018] In addition, the polyester herein may also be, for example, poly(trimethylene terephthalate), poly(butylene terephthalate), polyethylene naphthalate, or a combination thereof. In this embodiment, the polyester is preferably polyethylene terephthalate, poly(trimethylene terephthalate), or a combination thereof. In addition, copolymers may also be used, which particularly refer to copolymers that can be obtained by using two or more dicarboxylic acids and / or two or more diol components.

[0019] [First stage processing]

[0020] The aforementioned recovered material is subjected to a first stage of treatment to obtain a first liquid material and a first solid material.

[0021] It should be noted that the term "liquid" in this article is not limited to the object being completely liquid. For example, "liquid" may include liquid; and suspended matter suspended in or on the liquid. The particle size of the aforementioned suspended matter may be less than or equal to 1 millimeter (mm); or, according to the standard of ASTM E11-01, the aforementioned suspended matter may pass through a sieve with a mesh number of 18 or more. For another example, "liquid" may include a polymer solution (polymer colloid) or other similar colloids (colloid).

[0022] It should be noted that the term "solid" herein is not limited to a completely solid state. For example, a "solid" may include a solid; and a liquid attached to the solid or located between two solids through capillary phenomena. The "solid" may be dried in an appropriate manner (e.g., heating and / or reduced pressure drying) to obtain a solid that is almost free of liquid. Based on the total weight of the "solid", the weight of the solid after drying may be about 80% or more; preferably about 90% or more; and more preferably about 95% or more.

[0023] In this embodiment, the first stage of treatment may include acid treatment. For example, the aforementioned recyclables may be immersed in acid solution, and then the first liquid and the first solid may be separated from each other by an appropriate method (such as, but not limited to, filtering with a screen).

[0024] In one embodiment, the acid treatment in the first stage of treatment may involve immersing the recyclate in an acid solution (which may be referred to as: acid washing).

[0025] In one embodiment, the acid treatment in the first stage of treatment may be performed by immersing the recyclate in an acid solution and heating it (eg, heating it to about 50±5° C.), but the present invention is not limited thereto.

[0026] In one embodiment, the acid treatment in the first stage of treatment can be performed by immersing the recyclate in an acid solution and stirring and / or standing (e.g., stirring and / or standing for more than 30 minutes; or, stirring and / or standing for more than 60 minutes), but the present invention is not limited thereto.

[0027] In one embodiment, the acid treatment of the first stage treatment can be performed via an aqueous solution of an organic acid. If nitric acid, hydrochloric acid or sulfuric acid is used, it is easy to damage the acid treatment tank (such as: pickling tank; but not limited) or other possible metal tools (such as: stainless steel tools; but not limited). Sulfuric acid may cause other non-nylon fibers (such as: polyester fibers) to dissolve, resulting in reduced separation between liquid and solid. Hydrofluoric acid is more likely to cause industrial safety hazards. Oxalic acid has a low water solubility (such as: about 14.3g / 100ml@25℃), so it is more difficult to prepare a high-concentration aqueous solution at room temperature to dissolve nylon. Phosphoric acid has poor solubility in nylon.

[0028] In one embodiment, the acid treatment of the first stage of treatment can be performed via an aqueous solution of a fatty acid. Aromatic acids (such as, but not limited to, benzoic acid) have low water solubility, so it is difficult to prepare a high-concentration aqueous solution at room temperature to dissolve nylon. In addition, compared to nylon, other non-nylon fibers (such as polyester fibers or other polymers containing aromatic groups) may be more difficult to be dissolved by fatty acids.

[0029] In one embodiment, the acid treatment of the first stage treatment can be performed by an aqueous solution of a straight chain fatty acid. When comparing fatty acids with the same carbon number, straight chain fatty acids generally have better water solubility than sidechain fatty acids.

[0030] In one embodiment, the acid treatment of the first stage treatment may be performed by an aqueous solution of a straight chain fatty acid having a carbon number of 3 or less. The straight chain fatty acid having a carbon number of 3 or less may have better water solubility.

[0031] In one embodiment, the first stage of the acid treatment can be performed by an aqueous solution of formic acid (i.e., formic acid; secreted by ants, bees, and other hymenoptera) or acetic acid (i.e., acetic acid; produced by acetic acid bacteria). Formic acid and acetic acid are biological acids found in nature and are more eco-friendly in terms of application and / or treatment (e.g., waste liquid treatment, but not limited to).

[0032] In one embodiment, the acid treatment of the first stage treatment can be performed by an aqueous solution of formic acid, which can dissolve nylon more easily than acetic acid.

[0033] In one embodiment, the acid treatment of the first stage treatment may be performed by a 99 wt % formic acid aqueous solution.

[0034] In one embodiment, the first solid material may include other non-nylon polymers (eg polyester). However, it should be noted that the present invention does not exclude the first solid material from also including a small amount of nylon.

[0035] In one embodiment, the first liquid may include an acid solution and nylon or a nylon suspension dissolved in the acid solution.

[0036] In one embodiment, based on the total amount of nylon in the recyclate, the amount of nylon in the first liquid is about 75 wt % to 90 wt %, and the amount of nylon in the first solid is correspondingly about 25 wt % to 10 wt %.

[0037] [Second stage processing]

[0038] The first liquid material is subjected to a second-stage treatment to obtain a second liquid material and a second solid material.

[0039] In this embodiment, the second stage of treatment may include dilution. For example, the solvent used in the acid treatment in the first stage of treatment may be added to the first liquid, and then the second liquid and the second solid may be separated from each other by an appropriate method (such as, but not limited to, filtering with a mesh or standing to separate).

[0040] In one embodiment, the second stage treatment method may also include adding the aforementioned solvent to the aforementioned first liquid and then cooling the solution (e.g., cooling to room temperature (about 25° C.); or, cooling to below room temperature and above freezing point), but the present invention is not limited thereto.

[0041] In one embodiment, the second stage treatment method may also include adding the aforementioned solvent to the aforementioned first liquid, and then stirring and / or standing the solution (e.g., stirring for 3 minutes and standing for more than 30 minutes; or, stirring for 5 minutes and standing for more than 60 minutes), but the present invention is not limited to this.

[0042] In one embodiment, the first stage treatment may include acid treatment via a 99 wt % formic acid aqueous solution, and the second stage treatment may include adding water to the first liquid to reduce the formic acid concentration in the solution to about 60 wt % to 70 wt %.

[0043] In one embodiment, the second solid object may include nylon.

[0044] In one embodiment, the second liquid may include an acid solution and nylon or nylon suspension dissolved in the acid solution. The concentration of the acidic substance in the second liquid is less than the concentration of the acidic substance in the first liquid.

[0045] [Third stage processing]

[0046] The first solid material is subjected to a third stage of treatment to obtain a third liquid material and a third solid material.

[0047] In this embodiment, the third stage treatment may include an acid treatment. In one embodiment, the acid treatment method of the third stage treatment may be similar to the acid treatment method of the first stage treatment. For example, the first solid may be immersed in an acid solution, and then the third liquid and the third solid may be separated from each other by an appropriate method (such as filtering with a sieve, but not limited thereto).

[0048] In one embodiment, the acid treatment in the third stage may be performed by immersing the first solid in an acid solution and heating it (eg, heating it to about 70±5° C. to 100±5° C.), but the present invention is not limited thereto.

[0049] In one embodiment, the acid treatment in the third stage can be performed by immersing the first solid in an acid solution and stirring and / or standing (e.g., stirring and / or standing for more than 30 minutes; or, stirring and / or standing for more than 60 minutes), but the present invention is not limited thereto.

[0050] In one embodiment, the solute and solvent used in the acid treatment of the third stage of treatment may be the same as or similar to the solute and solvent used in the acid treatment of the first stage of treatment.

[0051] In one embodiment, the acid concentration of the acid treatment in the third stage is different from that in the first stage; and the acid concentration of the acid treatment in the third stage is different from that in the second liquid.

[0052] In one embodiment, the acid concentration of the acid solution in the third stage of the acid treatment is less than that in the first stage of the acid treatment; and the acid concentration of the acid solution in the third stage of the acid treatment is greater than the acid concentration of the second liquid.

[0053] In one embodiment, a 99 wt% formic acid aqueous solution can be mixed with a 60-70 wt% recycled formic acid aqueous solution, and then the mixed solution can be used as the acid solution for the third stage of treatment. In this way, the overall amount of formic acid used can be reduced. In one embodiment, the concentration of formic acid in the mixed solution can be greater than 80 wt%. In this way, a better dissolving effect can be achieved on nylon.

[0054] In one embodiment, the aforementioned recovered formic acid aqueous solution may include the second liquid obtained after the second stage treatment (including: the second liquid obtained in this treatment cycle; and / or the second liquid obtained in the previous treatment cycle when the method of the present invention is performed multiple times); and / or, the fourth liquid obtained after the fourth stage treatment (described in detail below) performed in the previous treatment cycle (when the method of the present invention is performed multiple times). In this way, the overall usage of formic acid can be reduced, and the nylon or nylon suspension dissolved in the acid solution in the recovered formic acid aqueous solution (such as: the second liquid and / or the fourth liquid) can continue to be subsequently recovered, thereby increasing the amount of nylon recovered.

[0055] In one embodiment, the third solid may include other non-nylon polymers (such as polyester). However, it should be noted that the present invention does not exclude the third solid from also including a very small amount of nylon.

[0056] In one embodiment, the proportion of nylon in the third solid (which may be the weight ratio of nylon to the entire third solid) is smaller than the proportion of nylon in the first solid (which may be the weight ratio of nylon to the entire first solid).

[0057] In one embodiment, the proportion of polyester in the third solid (which may be the weight ratio of polyester to the entire third solid) is greater than the proportion of polyester in the first solid (which may be the weight ratio of polyester to the entire first solid).

[0058] In one embodiment, the third liquid may include an acid solution and nylon or a nylon suspension dissolved in the acid solution.

[0059] In one embodiment, the amount of nylon in the third liquid may be about 90 wt% or more, or more preferably 95 wt% or more, based on the total amount of nylon in the first solid. That is, after two stages of acid treatment (i.e., acid treatment in the first stage and acid treatment in the third stage), the nylon in the recyclate may be almost dissolved and separated in the subsequent steps.

[0060] [Fourth stage processing]

[0061] The third liquid material is subjected to a fourth stage of treatment to obtain a fourth solid material and a fourth liquid material.

[0062] In this embodiment, the fourth stage of treatment may include dilution. For example, the solvent used in the acid treatment in the first stage of treatment or the third stage of treatment may be added to the third liquid, and then the fourth liquid and the fourth solid may be separated from each other by an appropriate method (such as, but not limited to, filtering with a mesh or standing to separate).

[0063] In one embodiment, the fourth stage of treatment may further include adding the aforementioned solvent to the aforementioned third liquid and then cooling the solution (eg, cooling to room temperature (about 25° C.); or, cooling to below room temperature and above freezing point), but the present invention is not limited thereto.

[0064] In one embodiment, the fourth stage treatment method may also include adding the aforementioned solvent to the aforementioned third liquid, and then stirring and / or standing the solution (e.g., stirring for 3 minutes and standing for more than 30 minutes; or, stirring for 5 minutes and standing for more than 60 minutes), but the present invention is not limited to this.

[0065] In one embodiment, the first stage treatment may include acid treatment of the first stage treatment via a 99 wt % formic acid aqueous solution, the third stage treatment may include acid treatment of the third stage treatment via two stages of formic acid aqueous solutions of different concentrations, and the fourth stage treatment may include adding water to the aforementioned third liquid to reduce the formic acid concentration in the solution to about 60 wt % to 70 wt %.

[0066] In one embodiment, the fourth solid object may include nylon.

[0067] In one embodiment, the fourth liquid may include an acid solution and nylon or nylon suspension dissolved in the acid solution. The concentration of the acidic substance in the fourth liquid is less than the concentration of the acidic substance in the third liquid.

[0068] [Recycling of nylon]

[0069] The second solid and / or the fourth solid comprising nylon can basically be recycled and reused by appropriate methods (such as nylon drawing or nylon granulation, but not limited to).

[0070] In one embodiment, the second solid and / or the fourth solid may be further washed with water to reduce the concentration of the acid solution in the second solid and / or the fourth solid, but the present invention is not limited thereto.

[0071] In one embodiment, the second solid material and / or the fourth solid material may be dried, but the present invention is not limited thereto.

[0072] [Recycling of polyester]

[0073] The third solid material including polyester can basically be recycled and reused by appropriate means (such as polyester granulation, but not limited to).

[0074] In one embodiment, the third solid may be further washed with water to reduce the concentration of the acid solution in the third solid, but the present invention is not limited thereto.

[0075] In one embodiment, the third solid material may be dried, but the present invention is not limited thereto.

[0076] [Practicality]

[0077] Through the method of the present invention, nylon or polyester in the recyclate can be recovered. Moreover, the recycled nylon or polyester can be reused. The way of reuse is, for example, but not limited to: the manufacture of nylon-containing materials such as fabrics, curtains, tires, etc. The processing methods of recycled polyester include physical reprocessing or chemical reprocessing. Physical reprocessing includes using an extruder to melt the treated polyester and then extrude it into granules. Chemical reprocessing includes depolymerizing the recovered polyester with a chemical depolymerization liquid, and then repolymerizing the monomers and / or oligomers obtained after depolymerization under specific conditions, and then granulating; the chemical depolymerization liquid can be water, methanol, ethanol, ethylene glycol, diethylene glycol or any combination. The processing method of recycled polyester can refer to the Taiwan Patent Application No. 110113065 and / or the Chinese Invention Patent Application No. 202110825541.8.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for treating waste fabrics containing polyester and nylon, characterized in that: include: Step a: providing waste fabrics containing polyester and nylon; Step b: performing a first-stage treatment on the waste fabric to obtain a first liquid and a first solid, wherein the amount of nylon in the first liquid is 75wt% to 90wt%, and the amount of nylon in the first solid is 25wt% to 10wt% based on the total amount of nylon in the waste fabric; Step c: performing a 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 a third solid, wherein the weight ratio of nylon in the third solid is less than the weight ratio of nylon in the first solid, and the weight ratio of polyester in the third solid is greater than the weight ratio of polyester in the first solid; and Step e: performing a fourth stage treatment on the third liquid to obtain a fourth liquid and a fourth solid, wherein: The first stage treatment includes acid treatment; The second stage of treatment includes dilution; The acid concentration of the second liquid is lower than the acid concentration of the first liquid; The third stage treatment includes acid treatment; The fourth stage of treatment includes dilution; The acid concentration of the fourth liquid substance is lower than the acid concentration of the third liquid substance; The third solid comprises recycled polyester, and the second solid and the fourth solid comprise recycled nylon; The acid treatment in the first stage and the acid treatment in the third stage are performed by acid treatment only with an aqueous solution of a straight-chain fatty acid; The acid concentration of the acid treatment in the third stage is less than the acid concentration of the acid treatment in the first stage, and the acid concentration of the acid treatment in the third stage is greater than the acid concentration of the second liquid; Step a, step b, step d and step e are performed N times, where N is greater than or equal to 2; Step c is performed M times, where M is less than or equal to N; The acid treatment of the third stage treatment for the Nth time includes acid treatment of the second liquid for the Mth time; and The acid treatment of the third stage treatment for the Nth time includes acid treatment via the fourth liquid for the Pth time, wherein P is less than N.

2. The method for treating waste fabrics containing polyester and nylon according to claim 1, characterized in that: The straight-chain fatty acid comprises formic acid or acetic acid.

3. The method for treating waste fabrics containing polyester and nylon according to claim 1, characterized in that: Wherein the step a, the step b, the step c, the step d and the step e are performed in sequence.

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