Method for improving steam decolorization rate of waste polyester textiles

Abstract

The present invention belongs to the technical field of waste polyester textile recycling. Disclosed is a method for improving the steam decolorization rate of waste polyester textiles. The method comprises: adding a phase change material to waste polyester textiles, the weight of the phase change material being 1% to 5% of the weight of the polyester in the waste polyester textiles; mixing uniformly to obtain waste polyester textiles to be decolorized, and then performing steam decolorization. The present invention solves the problem that when a large amount of waste polyester textiles are treated by steam decolorization, the steam diffusion resistance becomes large and it is difficult to enter the interior of the pile, resulting in decolorizing steam being unable to fully contact the waste polyester textiles, thus resulting in a low decolorization rate and uneven decolorization when the amount of waste polyester textiles is large. The method of the present invention improves the decolorization rate in this case to more than 97%, and is suitable for decolorization treatment on waste polyester textiles such as pure polyester, polyester-cotton, polyester-nylon, polyester-ammonia, and other polyester blended products.

Description

A method for improving steam decolorization rate of waste polyester textiles Technical Field

[0001] The invention belongs to the technical field of recycling waste polyester textiles and relates to the decolorization of waste polyester textiles, in particular to a method for improving the steam decolorization rate of waste polyester textiles. Background Art

[0002] As the production and sales of polyester (polyethylene terephthalate, PET) continue to grow, the amount of discarded polyester products is also increasing. Since polyester is often chemically colored during production, the wide variety of colors significantly limits the applications of recycled polyester textiles. Therefore, decolorization of waste polyester textiles has become a key process in polyester recycling.

[0003] Commonly used methods for decolorizing waste polyester textiles include immersion bleaching and steam bleaching. The former has the disadvantages of high water consumption and the need for drying of the polyester after decolorization. The existing steam bleaching method, such as the Chinese invention patent with publication number CN101644007A, heats the decolorizer to vaporize it and contact it with the polyester to dissolve the polyester dye. Although this method avoids the shortcomings of the immersion bleaching method and can ensure sufficient contact between the decolorizer vapor and the polyester when the processing volume of waste polyester textiles is small, when the processing volume increases, the waste polyester textiles will form accumulations on the metal mesh for steam bleaching. The waste polyester textile fabrics are thick or have a high knitting density, and the air tightness is relatively good. The steam diffusion resistance becomes large and it is difficult to enter the interior of the accumulation body, so that the decolorizer vapor cannot fully contact with the waste polyester textiles, which will lead to low decolorization rate and uneven decolorization.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving the steam decolorization rate of waste polyester textiles, so as to solve the problem of low decolorization rate and uneven decolorization when treating a large amount of waste polyester textiles by steam decolorization.

[0006] After long-term research on the decolorization method of waste polyester textiles, the inventor unexpectedly discovered that when phase change materials are used for steam decolorization of colored waste polyester textiles, the phase change material undergoes phase change under the influence of the high temperature of the decolorizer vapor, forming a local temperature difference inside the polyester pile, guiding the penetration of the decolorizer vapor, so that the steam and polyester are fully in contact, and the steam decolorization rate is significantly improved, thereby achieving an improved decolorization rate and uniform decolorization.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for improving the steam decolorization rate of waste polyester textiles, comprising adding a phase change material to the waste polyester textiles, mixing them evenly, obtaining the waste polyester textiles to be decolorized, and then performing steam decolorization;

[0009] Wherein, the amount of the phase change material is 1% to 5% of the weight of polyester in the waste polyester textiles;

[0010] The phase change temperature of the phase change material is not greater than the temperature of the decolorizing agent vapor in steam decolorization.

[0011] As a limitation of the present invention, the phase change material is a powdered solid. The powdered phase change material can be more evenly dispersed on the surface of the waste polyester textiles, thereby increasing the contact area between the phase change material and the waste polyester textiles.

[0012] As another limitation of the present invention, the phase change material is one or more of paraffin wax and polyethylene glycol, specifically one or more of industrial paraffin wax and polyethylene glycol with an average molecular weight of 600 to 20,000.

[0013] As a third limitation of the present invention, the phase change material is at least one of polyethylene glycol composite phase change materials, wherein the polyethylene glycol composite phase change material is a composite phase change material containing polyethylene glycol in its raw materials.

[0014] As a further limitation of the present invention, the polyethylene glycol composite phase change material is a polyethylene glycol-silicon oxide composite material, specifically a polyethylene glycol-silicon dioxide composite material.

[0015] As a fourth limitation of the present invention, the decolorizing agent used in the steam decolorization is a mixture of decolorizing agent I and decolorizing agent II in a mass ratio of 1:0.1-10;

[0016] The decolorizing agent I comprises at least one of N,N-dimethylformamide, ethylene glycol, acetic acid, aniline, dimethyl sulfoxide and N,N-dimethylacetamide;

[0017] The decolorizing agent II includes at least one of xylene, naphthalene and benzophenone.

[0018] Among them, the polarity of decolorizing agent I is higher than that of decolorizing agent II.

[0019] As another limitation of the present invention, the decolorizing agent used in the steam decolorization is N,N-dimethylformamide, dimethyl sulfoxide or ethylene glycol.

[0020] As a further limitation of the present invention, in the steam decolorization, the contact time between the decolorizer vapor and the waste polyester textile to be decolorized is not less than 0.5 h, preferably 2 h.

[0021] As a further limitation of the present invention, the waste polyester textiles are polyester-containing textiles with a polyester mass percentage of 65% to 99%;

[0022] The polyester-containing textiles include pure polyester, polyester-cotton, polyester-nylon, polyester-spandex and polyester blended textiles.

[0023] The polyester-containing textiles include but are not limited to waste scraps, waste silk, waste yarn, waste blocks, etc., which are waste textiles generated during the textile production process.

[0024] The polyester-containing textiles also include old clothing, old home textile products, old industrial textiles, etc., and waste textiles after use, including but not limited to old clothes, old sheets, old quilt covers, old pillowcases, old fabric products, old curtains, waste industrial textiles, etc.

[0025] Due to the adoption of the above technical solution, the present invention has the following technical advancements compared with the prior art:

[0026] (1) The present invention adds a phase change material with phase change properties to waste polyester textiles. When the decolorizing agent vapor rises, the temperature of the waste polyester textile pile increases, and the phase change material inside the pile reaches the phase change temperature and undergoes phase change, forming a local temperature difference, thereby guiding the decolorizing agent vapor to penetrate the pile with a high pile thickness or a high knitting density of the fabric, so that the decolorizing agent vapor can fully contact the polyester, thereby improving the decolorization uniformity and raising the decolorization rate to more than 97%;

[0027] (2) After steam decolorization treatment using the method of the present invention, the phase change material and the dye molecules in the waste polyester textiles are dissolved in the decolorizer vapor to form a decolorized waste liquid. The phase change material can be recovered by subsequent distillation of the decolorized waste liquid, thereby achieving resource conservation and reuse;

[0028] (3) When polyethylene glycol or polyethylene glycol composite phase change material is used in the present invention, polyethylene glycol has excellent properties such as suitable phase change temperature, large latent heat capacity, non-toxicity, low vapor pressure, and high thermochemical stability after long-term use, and has good recycling effect;

[0029] (4) The present invention uses decolorizer I and decolorizer II with different polarities, wherein the polarity of decolorizer I is higher than that of decolorizer II. The high-polarity decolorizer I can quickly dissolve the dye substance during the decolorization process, thereby improving the decolorization effect; while the lower-polarity decolorizer II has a polarity similar to that of the phase change material. Based on the principle of like dissolves like, it helps to guide the decolorizer vapor to penetrate the deposit with a high stacking thickness or a high knitting density of the fabric, so that the decolorizer vapor can fully contact the polyester, thereby improving the decolorization uniformity;

[0030] The invention is suitable for industrial decolorization treatment of a large amount of waste polyester textiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the description, but are not intended to limit the present invention.

[0032] FIG1 is a K / S value-wavelength diagram before and after treatment in Example 1 of the present invention;

[0033] FIG2 is a K / S value-wavelength diagram of Comparative Example 1 of the present invention before and after treatment;

[0034] FIG3 is a K / S value-wavelength diagram before and after treatment in Example 2 of the present invention;

[0035] FIG4 is a K / S value-wavelength diagram before and after treatment of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below through specific embodiments. All features disclosed in this specification, or steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, may be combined in any manner. It should be understood that the preferred embodiments described herein are intended only to illustrate and understand the present invention and are not intended to limit the present invention.

[0037] Unless otherwise specified, the materials and reagents used in the examples of the present invention can be obtained from commercial sources. Experimental methods without specific conditions in the examples are generally performed under conventional conditions or the conditions recommended by the manufacturer.

[0038] Example 1 A method for improving the steam decolorization rate of waste polyester textiles

[0039] This embodiment is a method for improving the steam decolorization rate of waste polyester textiles. The waste polyester textile processing volume is large, and specifically includes the following steps:

[0040] S1. 2.5 kg of colored waste polyester textiles containing polyester (pure polyester curtains with a polyester weight percentage of 65%) and 25 g of powdered polyethylene glycol 10000 (1% by weight of polyester in the waste polyester textiles) were uniformly mixed to obtain waste polyester textiles to be bleached;

[0041] S2. The waste polyester textile to be bleached is placed on a steam decolorization treatment metal mesh, with 60L N, N-dimethylformamide as a decolorizing agent, and steam decolorized;

[0042] The specific steps of steam decolorization are: stirring and heating the decolorizer to the boiling point of 153°C, maintaining the temperature for 2 hours, ensuring that the decolorizer vapor contacts the waste polyester textile to be decolorized, stopping heating, waiting for the decolorizer solution temperature to cool to room temperature, and then taking out the polyester, thus completing the steam decolorization of the waste polyester textile;

[0043] In this embodiment, the phase change temperature of the phase change material polyethylene glycol 10000 is about 65° C., which is not greater than the temperature of the decolorizing agent vapor.

[0044] Comparative Example 1: A method for steam decolorization of waste polyester textiles

[0045] This comparative example is a steam decolorization method for waste polyester textiles. The specific method is basically the same as that of Example 1, except that no phase change material is added. Specifically,

[0046] Place 2.5 kg of colored waste polyester textiles containing polyester on a metal mesh for steam decolorization treatment, use 60 L of N,N-dimethylformamide as a decolorizer, stir and heat the decolorizer to the boiling point of 153 ° C, maintain this temperature for 2 hours, stop heating, wait for the decolorizer solution temperature to cool to room temperature, take out the polyester, and complete the steam decolorization of waste polyester textiles.

[0047] Decolorization effect verification:

[0048] The decolorization rates of waste polyester textiles before and after treatment by the two methods of Example 1 and Comparative Example 1 were respectively tested to obtain a K / S value-wavelength graph before and after treatment of Example 1, as shown in FIG1 , and a K / S value-wavelength graph before and after treatment of Comparative Example 1, as shown in FIG2 .

[0049] The decolorization rate is calculated by the change in K / S value before and after treatment. The decolorization rate calculation formula is as follows:

[0050] △K / S=(K / S value before bleaching - K / S value after bleaching)÷K / S value before bleaching×100%

[0051] The calculated decolorization rate of Example 1 is 97.1%, and the decolorization rate of Comparative Example 1 is 72.9%. The results show that when treating 2.5 kg of colored waste polyester textiles containing polyester, compared with Comparative Example 1, adding 1 wt% of phase change material using the method of Example 1 can significantly improve the steam decolorization rate of the waste polyester textiles.

[0052] Example 2 A method for improving the steam decolorization rate of waste polyester textiles

[0053] This embodiment is another method for improving the steam decolorization rate of waste polyester textiles. The processing amount of colored waste polyester textiles is only 40% of that in Example 1. The method specifically includes the following steps:

[0054] S1. 1 kg of colored waste polyester textiles containing polyester (pure polyester curtains with a polyester weight percentage of 65%) and 25 g (2.5% by weight of polyester in the waste polyester textiles) of polyethylene glycol 10000 were uniformly mixed to obtain waste polyester textiles to be bleached;

[0055] S2. The waste polyester textile to be bleached is placed on a steam decolorization treatment metal mesh, with 60L N, N-dimethylformamide as a decolorizing agent, and steam decolorized;

[0056] The specific steps of steam decolorization are: stirring and heating the decolorizer to the boiling point of 153°C, maintaining the temperature for 2 hours, ensuring that the decolorizer vapor contacts the waste polyester textile to be decolorized, stopping heating, waiting for the decolorizer solution to cool to room temperature, and then taking out the textile, thus completing the steam decolorization of the waste polyester textile;

[0057] In this embodiment, the phase change temperature of the phase change material polyethylene glycol 10000 is about 65° C., which is not greater than the temperature of the decolorizing agent vapor.

[0058] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and a K / S value-wavelength graph before and after treatment in Example 2 was obtained, as shown in FIG3 . The calculated decolorization rate was 98.9%.

[0059] Comparative Example 2: A method for steam decolorization of waste polyester textiles

[0060] This comparative example is a steam decolorization method for waste polyester textiles. The specific method is basically the same as that of comparative example 1, except that the processing amount of colored waste polyester textiles is only 40% of that of comparative example 1. Specifically,

[0061] Place 1 kg of colored waste polyester textiles containing polyester on a metal mesh for steam decolorization treatment. Use 60 L of N,N-dimethylformamide as a decolorizer. Stir and heat the decolorizer to the boiling point of 153°C. Maintain this temperature for 2 hours. Stop heating and wait for the decolorizer solution to cool to room temperature. Take out the polyester and mark it as decolorized polyester D2. The steam decolorization of the waste polyester textiles is completed.

[0062] The decolorization rates of the waste polyester textiles before and after treatment by the method of this comparative example were tested, and a K / S value-wavelength graph before and after treatment of comparative example 2 was obtained, as shown in FIG4 . The calculated decolorization rate was 98.8%.

[0063] By comparing Figures 1 to 4, it is shown that the method of the present invention can improve the steam decolorization rate of waste polyester textiles. When the processing amount is 1 kg, the steam decolorization rate of waste polyester textiles is increased from 98.8% to 98.9%; when the processing amount is 2.5 kg, the steam decolorization rate of waste polyester textiles is increased from 72.9% to 97.1%. The results show that the present invention improves the steam decolorization rate of waste polyester textiles by adding phase change materials, and especially solves the problem that when the processing amount increases, the decolorant vapor cannot fully contact with the waste polyester textiles, which leads to low decolorization and uneven decolorization.

[0064] Example 3 A method for improving the steam decolorization rate of waste polyester textiles

[0065] Example 3 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in this field, is that: ① colored waste polyester textiles containing 1.2 kg of polyester (a polyester-cotton quilt cover with a polyester mass ratio of 83%) and 12 g of industrial paraffin (1% of the weight of polyester in the waste polyester textiles) are evenly mixed to obtain the waste polyester textiles to be decolorized; ② 60 L of dimethyl sulfoxide is used as a decolorizing agent.

[0066] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 98.8%.

[0067] Example 4: A method for increasing the steam decolorization rate of waste polyester textiles

[0068] Example 4 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in this field, is that: ① colored waste polyester textiles containing 1.5 kg of polyester (polyester-nylon waste yarn with a polyester mass ratio of 72%) and 45 g of polyethylene glycol 600 (3% of the weight of polyester in the waste polyester textiles) are evenly mixed to obtain waste polyester textiles to be decolorized; ② 60 L of ethylene glycol is used as a decolorizing agent; ③ the contact time of the decolorizing agent vapor and the waste polyester textile to be decolorized is 0.5 h.

[0069] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 98.3%.

[0070] Example 5: A method for increasing the steam decolorization rate of waste polyester textiles

[0071] Example 5 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in this field, is that: ① colored waste polyester textiles containing 1.8 kg of polyester (used polyester-spandex clothes with a polyester mass ratio of 99%) are evenly mixed with 18 g of industrial paraffin (1% of the weight of polyester in the waste polyester textiles) to obtain waste polyester textiles to be decolorized; ② N,N-dimethylacetamide (decolorizer I) and xylene (decolorizer II) are mixed in a mass ratio of 1:0.1 to prepare 60 L of decolorizer for decolorization; ③ The contact time of the decolorizer vapor with the waste polyester textile to be decolorized is 4 hours.

[0072] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 98.3%.

[0073] Example 6 A method for improving the steam decolorization rate of waste polyester textiles

[0074] Example 6 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to the conventional adaptive adjustments in this field, is that: ① colored waste polyester textiles containing 2.5 kg of polyester (a polyester blended quilt cover with a polyester mass ratio of 80%) is evenly mixed with 125 g of polyethylene glycol-silicon dioxide composite material (5% of the weight of polyester in the waste polyester textiles) to obtain waste polyester textiles to be decolorized; ② 60 L of decolorizer is prepared by mixing ethylene glycol (decolorizer I) and naphthalene (decolorizer II) in a mass ratio of 1:5 for decolorization; ③ the contact time of the decolorizer vapor with the waste polyester textile to be decolorized is 6 hours.

[0075] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 98.4%.

[0076] Example 7 A method for improving the steam decolorization rate of waste polyester textiles

[0077] Example 7 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in this field, is that: ① colored waste polyester textiles containing 5 kg of polyester (polyester-cotton pillowcases with a polyester mass ratio of 90%) are evenly mixed with 75 g of polyethylene glycol 2000 (1.5% of the weight of polyester in the waste polyester textiles) to obtain waste polyester textiles to be decolorized; ② 60 L of decolorizing agent is prepared by mixing aniline (decolorizing agent I) and benzophenone (decolorizing agent II) in a mass ratio of 1:10 for decolorization.

[0078] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 98.2%.

[0079] In other embodiments, polyethylene glycol with an average molecular weight of 600 to 20,000 is selected as the phase change material, which can achieve the effect of improving the steam decolorization rate of waste polyester textiles.

[0080] Example 8: A method for increasing the steam decolorization rate of waste polyester textiles

[0081] Example 8 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as Example 1. The only difference, in addition to conventional adaptive adjustments in the field, is that: ① colored waste polyester textiles containing 10 kg of polyester (polyester-spandex fabric with a polyester mass ratio of 65%) and 200 g of polyethylene glycol 10000 (2% of the weight of polyester in the waste polyester textiles) are evenly mixed to obtain waste polyester textiles to be decolorized; ② decolorizer I is prepared by mixing equal amounts of dimethyl sulfoxide and N,N-dimethylacetamide, and decolorizer II is prepared by mixing xylene and benzophenone in a mass ratio of 1:2. Decolorizer I and decolorizer II are mixed to prepare 240 L of a mixed decolorizer for decolorization, and the mass ratio of decolorizer I to decolorizer II in the mixed decolorizer is 1:6; ③ the contact time of the decolorizer vapor with the waste polyester textile to be decolorized is 1 hour.

[0082] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 97.4%.

[0083] Example 9: A method for increasing the steam decolorization rate of waste polyester textiles

[0084] Example 9 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in this field, is that: ① colored waste polyester textiles containing 20 kg of polyester (polyester-cotton fiber with a polyester mass ratio of 65%) and 800 g of polyethylene glycol-silicon dioxide composite material (4% of the weight of polyester in the waste polyester textiles) are evenly mixed to obtain waste polyester textiles to be decolorized; ② ethylene glycol, acetic acid and aniline are mixed in a mass ratio of 1:3:5 to prepare decolorizer I, and xylene, naphthalene and benzophenone are mixed in a mass ratio of 1:6:2 to prepare decolorizer II. Decolorizer I and decolorizer II are mixed to prepare 240 L of mixed decolorizer for decolorization, and the mass ratio of decolorizer I and decolorizer II in the mixed decolorizer is 1:8.

[0085] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 97.2%.

[0086] Example 10 A method for increasing the steam decolorization rate of waste polyester textiles

[0087] Example 10 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in the field, is that: ① colored waste polyester textiles containing 10 kg of polyester (pure polyester fiber with a polyester mass ratio of 70%) and 200 g of industrial paraffin (2% of the weight of polyester in the waste polyester textiles) are evenly mixed to obtain waste polyester textiles to be decolorized; ② N,N-dimethylformamide and ethylene glycol are mixed in a mass ratio of 1:3 to prepare decolorizer I, and xylene and naphthalene are mixed in a mass ratio of 1:6 to prepare decolorizer II. Decolorizer I and decolorizer II are mixed to prepare 240 L of mixed decolorizer for decolorization, and the mass ratio of decolorizer I and decolorizer II in the mixed decolorizer is 1:10; ③ The contact time of the decolorizer vapor with the waste polyester textile to be decolorized is 1.5 hours.

[0088] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 97.4%.

[0089] Example 11 A method for increasing the steam decolorization rate of waste polyester textiles

[0090] Example 11 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in the field, is that: ① colored waste polyester textiles containing 10 kg of polyester (pure polyester fiber with a polyester mass ratio of 80%) are evenly mixed with 200 g (2% of the weight of polyester in the waste polyester textiles) of polyethylene glycol-silicon dioxide composite material; ② N,N-dimethylformamide and ethylene glycol are mixed in a mass ratio of 1:3 to prepare decolorizer I, and xylene and naphthalene are mixed in a mass ratio of 1:6 to prepare decolorizer II. Decolorizer I and decolorizer II are mixed to prepare 240 L of mixed decolorizer for decolorization, and the mass ratio of decolorizer I to decolorizer II in the mixed decolorizer is 1:10; ③ The contact time of the decolorizer vapor with the waste polyester textile to be decolorized is 1.5 hours.

[0091] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 97.4%.

[0092] Example 12: A method for increasing the steam decolorization rate of waste polyester textiles

[0093] Example 12 is a method for improving the steam decolorization rate of waste polyester textiles. The specific method is basically the same as that of Example 1. The only difference, in addition to conventional adaptive adjustments in the field, is that: ① colored waste polyester textiles containing 10 kg of polyester (polyester-cotton fiber with a polyester mass ratio of 70%) and 200 g (2% of the weight of polyester in the waste polyester textiles) of polyethylene glycol 2000 are evenly mixed to obtain waste polyester textiles to be decolorized; ② N,N-dimethylformamide and ethylene glycol are mixed in a mass ratio of 1:3 to prepare decolorizer I, and xylene and naphthalene are mixed in a mass ratio of 1:6 to prepare decolorizer II. Decolorizer I and decolorizer II are mixed to prepare a mixed decolorizer 240 L for decolorization, and the mass ratio of decolorizer I and decolorizer II in the mixed decolorizer is 1:10; ③ The contact time of the decolorizer vapor with the waste polyester textile to be decolorized is 1.5 hours.

[0094] The decolorization rates of waste polyester textiles before and after treatment using the method of this embodiment were tested, and the calculated decolorization rate was 97.8%.

[0095] In other embodiments, the phase change material is at least one of the polyethylene glycol composite phase change materials, the total amount of the phase change material is a value between 1% and 5% of the weight of polyester in the waste polyester textiles, the phase change temperature of the phase change material is lower than the steam temperature of the decolorizer in steam decolorization, and the effect of improving the steam decolorization rate of the waste polyester textiles can be achieved. Among them, the closer the phase change temperature of the phase change material is to the steam temperature of the decolorizer in steam decolorization, the better the decolorization effect.

[0096] In other embodiments, waste polyester textiles are polyester-containing textiles with a polyester content ranging from 65% to 99% by mass; including pure polyester, polyester-cotton, polyester-nylon, polyester-spandex, and polyester blended textiles, including but not limited to waste scraps, silk waste, yarn waste, and scraps, generated during the textile manufacturing process. Examples include used clothing, used home textiles, and used industrial textiles. Used textiles include but are not limited to used clothes, used sheets, used quilt covers, used pillowcases, used fabric products, used curtains, and used industrial textiles. All of the above embodiments achieved good decolorization results.

[0097] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art may still modify the technical solutions described in the above embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for improving the steam decolorization rate of waste polyester textiles, characterized in that: Phase change materials are added to waste polyester textiles, mixed evenly, to obtain waste polyester textiles to be decolorized, and then steam decolorized; Wherein, the amount of the phase change material is 1% to 5% of the weight of polyester in the waste polyester textiles; The phase change temperature of the phase change material is not greater than the temperature of the decolorizing agent vapor in steam decolorization.

2. The method for improving the steam decolorization rate of waste polyester textiles according to claim 1, characterized in that: The phase change material is a powdered solid.

3. The method for improving the steam decolorization rate of waste polyester textiles according to claim 1, characterized in that: The phase change material is one or more of paraffin and polyethylene glycol.

4. The method for improving the steam decolorization rate of waste polyester textiles according to claim 1, characterized in that: The phase change material is at least one of polyethylene glycol composite phase change materials; the polyethylene glycol composite phase change material is a composite phase change material containing polyethylene glycol in its raw materials.

5. The method for improving the steam decolorization rate of waste polyester textiles according to claim 4, characterized in that: The polyethylene glycol composite phase change material is a polyethylene glycol-silicon oxide composite material.

6. A method for improving the steam decolorization rate of waste polyester textiles according to any one of claims 1 to 5, characterized in that: The decolorizing agent used in the steam decolorization is a mixture of decolorizing agent I and decolorizing agent II in a mass ratio of 1:0.1-10; The decolorizing agent I comprises at least one of N,N-dimethylformamide, ethylene glycol, acetic acid, aniline, dimethyl sulfoxide and N,N-dimethylacetamide; The decolorizing agent II includes at least one of xylene, naphthalene and benzophenone.

7. A method for improving the steam decolorization rate of waste polyester textiles according to any one of claims 1 to 5, characterized in that: The decolorizing agent used in the steam decolorization is N,N-dimethylformamide, dimethyl sulfoxide or ethylene glycol.

8. The method for improving the steam decolorization rate of waste polyester textiles according to claim 7, characterized in that: During the steam decolorization, the contact time between the decolorizer vapor and the waste polyester textile to be decolorized is not less than 0.5 h.

9. A method for improving the steam decolorization rate of waste polyester textiles according to any one of claims 1 to 5 and 8, characterized in that: The waste polyester textiles are polyester-containing textiles with a polyester mass ratio of 65% to 99%; the polyester-containing textiles include pure polyester, polyester-cotton, polyester-nylon, polyester-spandex and polyester blended textiles.

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