Regeneration method of waste cotton / polyester fiber blended fabric

Abstract

The invention belongs to the technical field of textile material regeneration, and relates to a waste cotton / polyester fiber blended fabric regeneration method, which comprises: mixing a waste cotton / polyester fiber blended fabric with a first solvent, and carrying out heat preservation under the conditions of pressure of 0.1 MPa, temperature of T and stirring until polyester fibers in the waste cotton / polyester fiber blended fabric are completely dissolved, the polymerization degree of the cotton fibers is reduced to 700-950, separating filtrate and a filter cake, treating the filtrate to obtain regenerated polyester, and treating the filter cake to obtain regenerated cellulose fibers. By controlling the adding amount of the first solvent, the type of the first solvent, the temperature and other conditions, reduction of the polymerization degree of the cotton fibers is reasonably controlled, the situation that cellulose dissolution in the subsequent cotton fiber regeneration process is affected due to insufficient reduction of the polymerization degree is avoided, and meanwhile excessive reduction of the polymerization degree of the cotton fibers is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of textile material regeneration and relates to a method for regenerating a waste cotton / polyester fiber blended fabric. Background Art

[0002] With the rapid development of the global textile industry, the amount of waste textiles is increasing, which not only occupies a large amount of land resources, but also causes serious pollution to the environment. Therefore, the recycling and reuse of waste textiles has become an environmental challenge that needs to be solved urgently. Among them, the recycling problem of waste cotton / polyester blended fabrics is particularly prominent as a material that is widely used in textiles and has a huge output. Due to the mixed entanglement of cotton and polyester components, the recycling method brings technical complexity and high cost, making the separation and reprocessing of fibers extremely difficult. Therefore, it is of great practical significance to develop a simple, efficient and environmentally friendly separation and regeneration process to solve the recycling problem of cotton / polyester blended fabrics.

[0003] There are two main methods for separating waste cotton / polyester blended fabrics: one is to retain cotton fibers by selectively dissolving polyester fibers, and the other is to retain polyester fibers by dissolving cotton fibers. The former utilizes the excellent chemical stability of cotton fibers to avoid the loss of cotton fibers during the dissolution process. The operation is relatively simple and helps to achieve efficient recovery of polyester fibers. The latter requires precise selection of solvents to ensure that only cotton fibers are dissolved without destroying the structure of polyester fibers. Since cotton fibers are natural fibers with strong chemical stability and are not easily dissolved by most organic solvents, by selecting solvents that can dissolve polyester fibers for separation, intact cotton fibers can be retained for recycling or reprocessing, which helps to recycle resources. In contrast, the process of dissolving cotton fibers may lead to excessive degradation of cotton fibers, thereby affecting the quality of recycling. Therefore, from the perspective of ease of operation and resource recovery efficiency, the method of dissolving polyester fibers and retaining cotton fibers usually has obvious advantages.

[0004] The patent application number CN118685473A discloses a method for high-value utilization of waste polyester-cotton. The method uses organic solvents such as hexafluoroisopropanol, γ-valerolactone or dimethyl sulfoxide to dissolve polyester (PET) and separate insoluble cotton fibers. Subsequently, enzymatic degradation is carried out under the action of PET degrading enzymes to generate terephthalic acid crystals (TPA) and ethylene glycol (EG) solutions. At the same time, the cotton fibers are treated with alkali solution and then enzymatically degraded to obtain a glucose solution. However, this method ultimately converts cellulose into glucose, and its added value is low.

[0005] The patent application publication number CN109467740A discloses a method for recycling waste polyester-cotton blended fabrics. The method comprises the following steps: first, using an ester solvent to dissolve polyester at high temperature; then, obtaining a polyester solution and cotton fiber insolubles by solid-liquid separation; then, treating the polyester solution to recover polyester; and finally, treating the cotton fiber insolubles to obtain cellulose regenerated fibers. However, the patent requires further reducing the polymerization degree of cotton fibers by adding hydrogen peroxide after dissolving polyester with an organic solvent, and the operation is relatively complicated. In addition, since the organic solvent itself has a weak polarity, it has limited effect on the polymerization degree of cellulose, resulting in low solubility of cotton fibers, which affects the production efficiency of the subsequent wet spinning process. In addition, each step of the method requires precise control of temperature, time and the amount of chemicals added, which makes the entire operation process relatively complicated.

[0006] If a method can be provided that can reduce the degree of polymerization of cotton fibers while using an organic solvent to dissolve polyester and ensure that the cotton fibers have a high solubility in the subsequent cellulose regeneration process, then this will be of great practical significance. Summary of the invention

[0007] The purpose of the invention is to solve the problems existing in the prior art and provide a method for regenerating waste cotton / polyester fiber blended fabrics.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for regenerating a waste cotton / polyester fiber blended fabric comprises mixing the waste cotton / polyester fiber blended fabric and a first solvent, and then keeping the mixture warm under a pressure of 0.1 MPa, a temperature of T, and stirring until the polyester fibers in the waste cotton / polyester fiber blended fabric are completely dissolved and the polymerization degree of the cotton fibers is reduced to 700-950, separating a filtrate and a filter cake, treating the filtrate to obtain regenerated polyester, and treating the filter cake to obtain regenerated cellulose fibers;

[0010] The polyester fiber content in the waste cotton / polyester fiber blended fabric is 10-90wt%, and the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:4-10;

[0011] The first solvent is NMP (N-methylpyrrolidone), DMF (dimethylformamide), DMAc (dimethylacetamide), HMPA (hexamethylphosphoric acid triamide) or DMSO (dimethyl sulfoxide); or, the first solvent is a mixture of NMP and DMAc, and the mass ratio of NMP to DMAc is 1:1, 2:1 or 3:1; or, the first solvent is a mixture of NMP and HMPA, and the mass ratio of NMP to HMPA is 7:3, 8:2 or 6:4; or, the first solvent is a mixture of NMP and DMSO, and the mass ratio of NMP to DMSO is 1:1 or 2:1;

[0012] T is 130-190℃.

[0013] Traditional regenerated cellulose fiber production mostly uses wood pulp fiber because of its low degree of polymerization and easy dissolution. However, the regeneration of waste cotton / polyester fiber blended fabrics faces the challenge of high degree of polymerization of cotton fiber. The existing cotton fiber depolymerization methods, such as inorganic or organic acid degradation, are often difficult to accurately control the reduction of degree of polymerization, which may lead to unstable quality of regenerated cellulose fiber.

[0014] The present invention reasonably controls the reduction of the polymerization degree of cotton fibers by controlling the addition amount of the first solvent, the type of the first solvent, the temperature and other conditions, thereby avoiding that the polymerization degree is not reduced enough to affect the cellulose dissolution in the subsequent cotton fiber regeneration process, and at the same time avoiding excessive reduction of the polymerization degree of cotton fibers.

[0015] The present invention can reduce the polymerization degree of cotton fiber while using an organic solvent to dissolve polyester, and ensure that the cotton fiber has a high solubility in the subsequent cellulose regeneration process. The specific reasons are as follows:

[0016] The first solvent is a polar solvent, which effectively destroys the hydrogen bonds and van der Waals forces between the polyester molecular chains through polar interactions. Polar solvents can form hydrogen bonds or dipole-dipole interactions with the carbonyl groups in the polyester molecules, thereby promoting the dissociation of the polyester molecular chains. Under high temperature conditions, the interaction between the first solvent and the polyester molecular chains is further enhanced, making it easier for the first solvent molecules to penetrate into the amorphous and crystalline regions of the polyester, thereby improving the dissolution efficiency. In addition, the polar functional groups of the first solvent can form competitive hydrogen bonds with the hydroxyl groups on the cellulose molecular chains, weakening the hydrogen bonding between cellulose molecules. This process causes the ratio of the crystalline and amorphous regions of cellulose to change, and the degree of polymerization is reduced, but it is not enough to dissolve the cellulose, making its chain structure looser and easier to separate. At the same time, the mechanical stirring and high temperature conditions during the dissolution process further promote the breakage of the cellulose molecular chains and further reduce the degree of polymerization of cellulose. This change helps to accelerate the dissolution rate of cellulose and increase its solubility in the subsequent cellulose regeneration process, providing more efficient conditions for subsequent processing and conversion.

[0017] As the preferred technical solution:

[0018] A method for regenerating a waste cotton / polyester fiber blended fabric as described above, wherein the initial polymerization degree of the cotton fiber in the waste cotton / polyester fiber blended fabric is 1500-3000, and the polymerization degree of the polyester fiber is 100-200;

[0019] The total insulation time is t2. When the insulation reaches t1, the polyester fiber in the waste cotton / polyester fiber blended fabric is completely dissolved. <t2;

[0020] When the first solvent is NMP, T is 130-190°C, t1 is 5-30min, 30min <t2<190min;

[0021] When the first solvent is DMF, T is 130-150°C, t1 is 15-30min, 110min <t2<190min;

[0022] When the first solvent is DMAc, T is 140-160°C, t1 is 10-30min, 170min <t2<250min;

[0023] When the first solvent is HMPA, T is 150-180°C, t1 is 30-60min, 200min <t2<250min;

[0024] When the first solvent is DMSO, T is 150-170℃, t1 is 5-15min, 160min <t2<190min;

[0025] When the first solvent is a mixture of NMP and DMAc, T is 140-190°C, t1 is 5-30min, 20min <t2<220min;

[0026] When the first solvent is a mixture of NMP and HMPA, T is 150-190°C, t1 is 30-60min, 140min <t2<250min;

[0027] When the first solvent is a mixture of NMP and DMSO, T is 140-190°C, t1 is 5-30min, 90min <t2<180min。

[0028] The first solvent selected in the present invention has high dissolving power and dissolving efficiency, and in particular, exhibits more efficient dissolving performance than traditional solvents under normal pressure, and can effectively break the interaction between polyester molecules and quickly dissolve polyester under low temperature conditions. In particular, the present invention finds that when the first solvent is a mixture, the integrity of the cotton fiber can be better preserved under the premise of effectively dissolving the polyester.

[0029] In the above-mentioned method for regenerating waste cotton / polyester fiber blended fabric, the stirring speed is 50-300r / min.

[0030] A method for regenerating waste cotton / polyester fiber blended fabric as described above, wherein the material of the polyester fiber in the waste cotton / polyester fiber blended fabric is one or more of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid (PLA), polybutylene succinate (PBS) and polyarylate.

[0031] The specific process of treating the filtrate to obtain the regenerated polyester in the above-mentioned method for regenerating the waste cotton / polyester fiber blended fabric is as follows: first, a decolorizing agent is added to the filtrate (used to eliminate the dye color in the waste cotton / polyester fiber blended fabric to ensure the color and quality of the regenerated product), and the reaction is carried out at 60-100°C for 30-80 minutes, and then the system after the reaction is filtered to collect the new filtrate, and deionized water or ethanol is added thereto, and then mechanically stirred, and finally the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a regenerated polyester granular material with a b value ≤16 and an L value ≥60.

[0032] In the above-mentioned method for regenerating waste cotton / polyester fiber blended fabric, the decolorizing agent is one or more of sodium hypochlorite, hydrogen peroxide, activated carbon and sodium formaldehyde sulfoxylate, the mass ratio of the decolorizing agent to the filtrate is 1:20-50; the volume of deionized water or ethanol is more than 5 times the volume of the new filtrate.

[0033] In the above-mentioned method for regenerating waste cotton / polyester fiber blended fabric, the regenerated polyester granules are spun to obtain regenerated polyester fibers.

[0034] According to the above-mentioned method for regenerating a waste cotton / polyester fiber blended fabric, the process of processing the filter cake to obtain regenerated cellulose fiber is as follows: after dissolving the filter cake in a second solvent NMMO aqueous solution to obtain a first regenerated cellulose solution, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 60-110° C. for 15-80 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fiber, wherein the concentration of the NMMO aqueous solution is 80-86wt%.

[0035] In the above-mentioned method for regenerating waste cotton / polyester fiber blended fabric, the concentration of the first regenerated cellulose solution is 6-10wt%; the decolorizing agent is one or more of sodium hypochlorite, hydrogen peroxide, activated carbon and sodium formaldehyde sulfoxylate, and the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:10-50.

[0036] As described above, the method for regenerating waste cotton / polyester fiber blended fabrics, the process parameters of the spinning process include: spinning temperature 90-120°C, spinning speed 40-90m / min, draft ratio 1:3-6; the dry breaking strength of the regenerated cellulose fiber is 3-4cN / dtex, the dry breaking elongation is 10-15%, and the wet breaking strength is 2-3cN / dtex.

[0037] Beneficial effects:

[0038] (1) The present invention reasonably controls the reduction of the polymerization degree of cotton fibers by controlling the amount of the first solvent added, the type of the first solvent, the temperature and other conditions, thereby avoiding that the polymerization degree is not reduced enough to affect the dissolution of cellulose in the subsequent cotton fiber regeneration process, and at the same time avoiding excessive reduction of the polymerization degree of cotton fibers.

[0039] (2) The first solvent selected by the present invention has high dissolving power and dissolving efficiency, and in particular, exhibits more efficient dissolving performance than traditional solvents under normal pressure. Under low temperature conditions, it can effectively break the interaction between polyester molecules and quickly dissolve polyester. In particular, the present invention has found that when the first solvent is a mixture, it can better retain the integrity of cotton fibers while effectively dissolving polyester.

[0040] (3) The method of the present invention also has wide adaptability. It can be used not only to treat blended fabrics of cotton and polyester (PET), but also to treat blended fibers containing other types of polyester (such as PBT, PTT, etc.), which further broadens the application scope and market prospects of the method of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0042] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0043] Dry breaking strength, dry breaking elongation, wet breaking strength: measured in accordance with GB / T 14337-2022.

[0044] Degree of polymerization: measured according to ASTM D1795-13 (2021).

[0045] b value, L value: measured in accordance with GB / T 14190-2017 standard.

[0046] Example 1

[0047] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0048] (1) Preparation of materials;

[0049] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2400; the polyester fiber content is 10wt%, the material of polyester fiber is PET, and the polymerization degree of PET is 100;

[0050] First solvent: NMP;

[0051] Decolorizing agent: sodium hypochlorite;

[0052] Deionized water;

[0053] Second solvent: NMMO aqueous solution with a concentration of 80wt%;

[0054] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 130°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 50 r / min for 30 min to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric (at this time, the polymerization degree of the cotton fiber is 1400), and then the stirring is continued at the same stirring speed for 150 min to reduce the polymerization degree of the cotton fiber to 950. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:5;

[0055] (3) Treat the filtrate and filter cake separately;

[0056] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 60° C. for 30 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, and then drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:20, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0057] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 6wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 60°C for 15 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:10; and the process parameters of the spinning process include: spinning temperature 90°C, spinning speed 90m / min, and draft ratio 1:3.

[0058] Tests show that the b value of the recycled polyester granules is 16 and the L value is 60; the dry breaking strength of the regenerated cellulose fiber is 4 cN / dtex, the dry breaking elongation is 10%, and the wet breaking strength is 3 cN / dtex.

[0059] Comparative Example 1

[0060] A method for regenerating waste cotton / polyester fiber blended fabric, which is different from Example 1 only in that the first solvent is replaced by methyl benzoate of the same mass.

[0061] Due to the low polarity of methyl benzoate, it is unable to form sufficiently strong hydrogen bonds or dipole-dipole interactions with the carbonyl groups in the polyester molecules, which hinders the dissociation process of the polyester molecular chains and makes it difficult to penetrate into the amorphous and crystalline regions of the polyester. As a result, in step (2), the polyester fibers in the waste cotton / polyester fiber blended fabric are only partially dissolved. At the same time, methyl benzoate is difficult to destroy the hydrogen bonds between cellulose molecules. As a result, in step (2), the degree of polymerization of the cotton fibers (reduced to only 1700) cannot be effectively reduced, and the regenerated cellulose cannot be subsequently dissolved.

[0062] Comparative Example 2

[0063] A method for regenerating waste cotton / polyester fiber blended fabric, which is different from Example 1 only in that the first solvent is replaced by ethyl benzoate of the same mass.

[0064] Due to the low polarity of ethyl benzoate, it is unable to form sufficiently strong hydrogen bonds or dipole-dipole interactions with the carbonyl groups in the polyester molecules, which hinders the dissociation process of the polyester molecular chains and makes it difficult to penetrate into the amorphous and crystalline regions of the polyester. As a result, in step (2), the polyester fibers in the waste cotton / polyester fiber blended fabric are only partially dissolved. At the same time, ethyl benzoate is difficult to destroy the hydrogen bonds between cellulose molecules. As a result, in step (2), the degree of polymerization of the cotton fibers (reduced to only 1700) cannot be effectively reduced, and the regenerated cellulose cannot be subsequently dissolved.

[0065] Comparative Example 3

[0066] A method for regenerating waste cotton / polyester fiber blended fabric, which is different from Example 1 only in that: in step (2), the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:0.5.

[0067] Since the amount of the first solvent added is too low, only the surface of the polyester fiber in the blended fabric is dissolved, while the interior remains solid; at the same time, due to insufficient solvent, it can only work on the surface of the cotton fiber and is difficult to penetrate into the interior of the cotton fiber. Therefore, the degree of polymerization of the cotton fiber is not reduced effectively (only reduced to 1600), resulting in the inability to effectively dissolve the regenerated cellulose subsequently.

[0068] Comparative Example 4

[0069] A method for regenerating waste cotton / polyester fiber blended fabric, which is different from Example 1 only in that the temperature of the system in step (2) is 120°C.

[0070] Since the temperature of the system in step (2) is too low, the polyester fibers in the waste cotton / polyester fiber blended fabric cannot be dissolved and the subsequent separation process cannot be carried out.

[0071] Example 2

[0072] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0073] (1) Preparation of materials;

[0074] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 1900; the polyester fiber content is 20wt%, the material of polyester fiber is PET, and the polymerization degree of PET is 150;

[0075] First solvent: NMP;

[0076] Decolorizing agent: sodium hypochlorite;

[0077] Ethanol;

[0078] Second solvent: NMMO aqueous solution with a concentration of 85wt%;

[0079] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 190°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 100 r / min for 5 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 30 minutes to reduce the polymerization degree of the cotton fiber to 880. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0080] (3) Treat the filtrate and filter cake separately;

[0081] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 70° C. for 40 minutes, then filtering the system after the reaction, collecting a new filtrate, adding ethanol thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granule, and spinning the regenerated polyester granule to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:25, and the volume of the ethanol is more than 5 times the volume of the new filtrate;

[0082] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 7wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 70°C for 20 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:15; and the process parameters of the spinning process include: a spinning temperature of 100°C, a spinning speed of 60m / min, and a draft ratio of 1:4.

[0083] Tests show that the b value of the recycled polyester granules is 15 and the L value is 63; the dry breaking strength of the regenerated cellulose fiber is 3.8 cN / dtex, the dry breaking elongation is 10%, and the wet breaking strength is 2.9 cN / dtex.

[0084] Example 3

[0085] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0086] (1) Preparation of materials;

[0087] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2000; the polyester fiber content is 30wt%, the material of polyester fiber is PET, and the polymerization degree of PET is 150;

[0088] First solvent: DMF;

[0089] Decolorizing agent: sodium hypochlorite;

[0090] Deionized water;

[0091] Second solvent: NMMO aqueous solution with a concentration of 82wt%;

[0092] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 130°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 150 r / min for 30 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 150 minutes to reduce the polymerization degree of the cotton fiber to 850. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0093] (3) Treat the filtrate and filter cake separately;

[0094] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 80° C. for 50 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, and then drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:30, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0095] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 8wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 80°C for 30 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:20; and the process parameters of the spinning process include: a spinning temperature of 110°C, a spinning speed of 80m / min, and a draft ratio of 1:5.

[0096] Tests show that the b value of the recycled polyester granules is 14 and the L value is 62; the dry breaking strength of the regenerated cellulose fiber is 3.6 cN / dtex, the dry breaking elongation is 12%, and the wet breaking strength is 2.5 cN / dtex.

[0097] Example 4

[0098] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0099] (1) Preparation of materials;

[0100] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2200; the polyester fiber content is 40wt%, the material of polyester fiber is PTT, and the polymerization degree of PTT is 100;

[0101] First solvent: DMF;

[0102] Decolorizing agent: sodium hypochlorite;

[0103] Deionized water;

[0104] Second solvent: NMMO aqueous solution with a concentration of 80wt%;

[0105] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 150° C., and the waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 200 r / min for 15 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 100 minutes to reduce the polymerization degree of the cotton fiber to 820, and then the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0106] (3) Treat the filtrate and filter cake separately;

[0107] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 90° C. for 60 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, and then drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:35, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0108] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 9wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 90°C for 40 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:25; and the process parameters of the spinning process include: a spinning temperature of 100°C, a spinning speed of 70m / min, and a draft ratio of 1:6.

[0109] Tests show that the b value of the recycled polyester granules is 13 and the L value is 65; the dry breaking strength of the regenerated cellulose fiber is 3.4 cN / dtex, the dry breaking elongation is 14%, and the wet breaking strength is 2.4 cN / dtex.

[0110] Example 5

[0111] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0112] (1) Preparation of materials;

[0113] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2300; the polyester fiber content is 50wt%, the material of polyester fiber is PTT, and the polymerization degree of PTT is 80;

[0114] First solvent: DMAc;

[0115] Decolorizing agent: hydrogen peroxide;

[0116] Ethanol;

[0117] Second solvent: NMMO aqueous solution with a concentration of 85wt%;

[0118] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 140°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 250 r / min for 30 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 210 minutes to reduce the polymerization degree of the cotton fiber to 790. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:5;

[0119] (3) Treat the filtrate and filter cake separately;

[0120] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, and the reaction is carried out at 100° C. for 70 minutes, and then the system after the reaction is filtered to collect a new filtrate, and ethanol is added thereto, and then mechanically stirred, and finally the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a regenerated polyester granular material, and the regenerated polyester granular material is spun to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:40, and the volume of the ethanol is more than 5 times the volume of the new filtrate;

[0121] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 10wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 100°C for 50 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:30; and the process parameters of the spinning process include: a spinning temperature of 90°C, a spinning speed of 50m / min, and a draft ratio of 1:3.

[0122] Tests show that the b value of the recycled polyester granules is 12 and the L value is 68; the dry breaking strength of the regenerated cellulose fiber is 3.1 cN / dtex, the dry breaking elongation is 15%, and the wet breaking strength is 2.2 cN / dtex.

[0123] Example 6

[0124] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0125] (1) Preparation of materials;

[0126] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2100; the polyester fiber content is 60wt%, the material of polyester fiber is PTT, and the polymerization degree of PTT is 120;

[0127] First solvent: DMAc;

[0128] Decolorizing agent: hydrogen peroxide;

[0129] Ethanol;

[0130] Second solvent: NMMO aqueous solution with a concentration of 82wt%;

[0131] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 160° C., and the mixture is first stirred at a stirring speed of 300 r / min for 10 min to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 170 min to reduce the polymerization degree of the cotton fiber to 750, and then the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0132] (3) Treat the filtrate and filter cake separately;

[0133] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, and the reaction is carried out at 100° C. for 80 minutes, and then the system after the reaction is filtered to collect a new filtrate, and ethanol is added thereto, and then mechanically stirred, and finally the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a regenerated polyester granular material, and the regenerated polyester granular material is spun to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:45, and the volume of the ethanol is more than 5 times the volume of the new filtrate;

[0134] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 9wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 95°C for 60 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:35; and the process parameters of the spinning process include: a spinning temperature of 120°C, a spinning speed of 60m / min, and a draft ratio of 1:4.

[0135] Tests show that the b value of the recycled polyester granules is 11 and the L value is 70; the dry breaking strength of the regenerated cellulose fiber is 3cN / dtex, the dry breaking elongation is 15%, and the wet breaking strength is 2cN / dtex.

[0136] Example 7

[0137] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0138] (1) Preparation of materials;

[0139] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2200; the polyester fiber content is 70wt%, the material of polyester fiber is PBT, and the polymerization degree of PBT is 80;

[0140] First solvent: HMPA;

[0141] Decolorizing agent: hydrogen peroxide;

[0142] Deionized water;

[0143] Second solvent: NMMO aqueous solution with a concentration of 83wt%;

[0144] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 150° C., and the mixture is first stirred at a stirring speed of 250 r / min for 60 min to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 150 min to reduce the polymerization degree of the cotton fiber to 750, and then the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:8;

[0145] (3) Treat the filtrate and filter cake separately;

[0146] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 80° C. for 40 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granule, and spinning the regenerated polyester granule to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:30, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0147] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 7wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 100°C for 70 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:40; and the process parameters of the spinning process include: a spinning temperature of 110°C, a spinning speed of 70m / min, and a draft ratio of 1:5.

[0148] Tests show that the b value of the recycled polyester granules is 14 and the L value is 65; the dry breaking strength of the regenerated cellulose fiber is 3 cN / dtex, the dry breaking elongation is 15%, and the wet breaking strength is 2.1 cN / dtex.

[0149] Example 8

[0150] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0151] (1) Preparation of materials;

[0152] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2400; the polyester fiber content is 80wt%, the material of polyester fiber is PBT, and the polymerization degree of PBT is 120;

[0153] First solvent: HMPA;

[0154] Decolorizing agent: hydrogen peroxide;

[0155] Deionized water;

[0156] Second solvent: NMMO aqueous solution with a concentration of 81wt%;

[0157] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 180°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 300 r / min for 30 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then the stirring is continued at the same stirring speed for 210 minutes to reduce the polymerization degree of the cotton fiber to 700. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:10;

[0158] (3) Treat the filtrate and filter cake separately;

[0159] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 90° C. for 50 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:35, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0160] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 8wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 100°C for 80 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:45; and the process parameters of the spinning process include: a spinning temperature of 100°C, a spinning speed of 80m / min, and a draft ratio of 1:6.

[0161] Tests show that the b value of recycled polyester granules is 13 and the L value is 71; the dry breaking strength of regenerated cellulose fiber is 3.2 cN / dtex, the dry breaking elongation is 14%, and the wet breaking strength is 2.1 cN / dtex.

[0162] Comparative Example 5

[0163] A method for regenerating waste cotton / polyester fiber blended fabric, which is different from Example 8 only in that the temperature of the system in step (2) is 230°C.

[0164] Tests show that the dry breaking strength of regenerated cellulose fiber is 1.9 cN / dtex and the wet breaking strength is 1.3 cN / dtex.

[0165] Compared with Example 8, the dry breaking strength and wet breaking strength of the regenerated cellulose fiber are significantly reduced in Comparative Example 5. This is because the temperature of the system in step (2) is too high, and the degree of polymerization of the cotton fiber is excessively reduced (the final degree of polymerization is reduced to 400), which makes the molecular chain structure of the fiber weaker and the bearing capacity of the fiber decreases, thereby reducing the dry breaking strength. At the same time, the degree of polymerization of the cotton fiber is too low, resulting in too low crystallinity of the fiber, thereby reducing the wet breaking strength.

[0166] Comparative Example 6

[0167] A method for regenerating waste cotton / polyester fiber blended fabric, which is different from Example 8 only in that: in step (2), the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:15.

[0168] Tests show that the dry breaking strength of regenerated cellulose fiber is 2.6 cN / dtex and the wet breaking strength is 1.7 cN / dtex.

[0169] Compared with Example 8, the dry breaking strength and wet breaking strength of the regenerated cellulose fiber in Comparative Example 6 are significantly reduced. This is because the amount of the first solvent added is too high, and the degree of polymerization of the cotton fiber is excessively reduced (the final degree of polymerization is reduced to 500), which makes the molecular chain structure of the fiber weaker and the bearing capacity of the fiber decreases, thereby reducing the dry breaking strength; at the same time, the degree of polymerization of the cotton fiber is too low, resulting in too low crystallinity of the fiber, thereby reducing the wet breaking strength.

[0170] Example 9

[0171] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0172] (1) Preparation of materials;

[0173] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 1900; the polyester fiber content is 90wt%, the material of polyester fiber is PBT, and the polymerization degree of PBT is 120;

[0174] First solvent: DMSO;

[0175] Decolorizing agent: activated carbon, manufactured by Aladdin Company, product number C112241;

[0176] Deionized water;

[0177] Second solvent: NMMO aqueous solution with a concentration of 80wt%;

[0178] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 170°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 200 r / min for 5 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 180 minutes to reduce the polymerization degree of the cotton fiber to 880. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:4;

[0179] (3) Treat the filtrate and filter cake separately;

[0180] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 70° C. for 30 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, and then drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:40, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0181] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 9wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 85°C for 60 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:35; and the process parameters of the spinning process include: a spinning temperature of 120°C, a spinning speed of 50m / min, and a draft ratio of 1:4.

[0182] Tests show that the b value of the recycled polyester granules is 15 and the L value is 72; the dry breaking strength of the regenerated cellulose fiber is 3.8 cN / dtex, the dry breaking elongation is 10%, and the wet breaking strength is 2.8 cN / dtex.

[0183] Example 10

[0184] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0185] (1) Preparation of materials;

[0186] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2100; the polyester fiber content is 60wt%, the material of polyester fiber is PBS, and the polymerization degree of PBS is 100;

[0187] First solvent: DMSO;

[0188] Decolorizing agent: activated carbon, manufactured by Aladdin Company, product number C112241;

[0189] Ethanol;

[0190] Second solvent: NMMO aqueous solution with a concentration of 86wt%;

[0191] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 150° C., and the mixture is stirred at a stirring speed of 250 r / min for 15 minutes to completely dissolve the polyester fibers in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 140 minutes to reduce the polymerization degree of the cotton fibers to 900, and then the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:4;

[0192] (3) Treat the filtrate and filter cake separately;

[0193] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 60° C. for 40 minutes, then filtering the system after the reaction, collecting a new filtrate, adding ethanol thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granule, and spinning the regenerated polyester granule to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:25, and the volume of the ethanol is more than 5 times the volume of the new filtrate;

[0194] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 6wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 90°C for 70 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:30; and the process parameters of the spinning process include: a spinning temperature of 110°C, a spinning speed of 40m / min, and a draft ratio of 1:5.

[0195] Tests show that the b value of the recycled polyester granules is 14 and the L value is 74; the dry breaking strength of the regenerated cellulose fiber is 3.8 cN / dtex, the dry breaking elongation is 11%, and the wet breaking strength is 3 cN / dtex.

[0196] Embodiment 11

[0197] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0198] (1) Preparation of materials;

[0199] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2300; the polyester fiber content is 30wt%, the material of polyester fiber is PBS, and the polymerization degree of PBS is 200;

[0200] First solvent: a mixture of NMP and DMAc in a mass ratio of 1:1;

[0201] Decolorizing agent: activated carbon, manufactured by Aladdin Company, product number C112241;

[0202] Deionized water;

[0203] Second solvent: NMMO aqueous solution with a concentration of 80wt%;

[0204] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 140°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 50 r / min for 30 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 180 minutes to reduce the polymerization degree of the cotton fiber to 860. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0205] (3) Treat the filtrate and filter cake separately;

[0206] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 80° C. for 70 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granule, and spinning the regenerated polyester granule to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:20, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0207] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 7wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 80°C for 20 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:20; and the process parameters of the spinning process include: a spinning temperature of 120°C, a spinning speed of 50m / min, and a draft ratio of 1:6.

[0208] Tests show that the b value of recycled polyester granules is 12 and the L value is 71; the dry breaking strength of regenerated cellulose fiber is 3.7 cN / dtex, the dry breaking elongation is 11%, and the wet breaking strength is 2.7 cN / dtex.

[0209] Example 12

[0210] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0211] (1) Preparation of materials;

[0212] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 1500; the polyester fiber content is 70wt%, the material of polyester fiber is PET / PTT (the mass ratio of PET to PTT is 70:30), the polymerization degree of PET is 100, and the polymerization degree of PTT is 120;

[0213] First solvent: a mixture of NMP and DMAc in a mass ratio of 2:1;

[0214] Decolorizing agent: activated carbon, manufactured by Aladdin Company, product number C112241;

[0215] Deionized water;

[0216] Second solvent: NMMO aqueous solution with a concentration of 85wt%;

[0217] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 190°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 300 r / min for 5 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 20 minutes to reduce the polymerization degree of the cotton fiber to 780. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:7;

[0218] (3) Treat the filtrate and filter cake separately;

[0219] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, and the reaction is carried out at 100° C. for 60 minutes, and then the system after the reaction is filtered to collect a new filtrate, and deionized water is added thereto, and mechanical stirring is performed, and finally the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a regenerated polyester granular material, and the regenerated polyester granular material is spun to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:45, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0220] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 10wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 110°C for 60 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:45; and the process parameters of the spinning process include: a spinning temperature of 90°C, a spinning speed of 90m / min, and a draft ratio of 1:3.

[0221] Tests show that the b value of recycled polyester granules is 11 and the L value is 77; the dry breaking strength of regenerated cellulose fiber is 3.2 cN / dtex, the dry breaking elongation is 14%, and the wet breaking strength is 2.2 cN / dtex.

[0222] Example 13

[0223] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0224] (1) Preparation of materials;

[0225] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 1900; the polyester fiber content is 40wt%, the material of polyester fiber is PET / PBT (the mass ratio of PET to PBT is 60:40), the polymerization degree of PET is 150, and the polymerization degree of PBT is 120;

[0226] First solvent: a mixture of NMP and DMAc in a mass ratio of 3:1;

[0227] Decolorizing agent: activated carbon, manufactured by Aladdin Company, product number C112241;

[0228] Ethanol;

[0229] Second solvent: NMMO aqueous solution with a concentration of 84wt%;

[0230] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 180°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 250 r / min for 10 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 40 minutes to reduce the polymerization degree of the cotton fiber to 800. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:7;

[0231] (3) Treat the filtrate and filter cake separately;

[0232] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, and the reaction is carried out at 100° C. for 50 minutes, and then the system after the reaction is filtered to collect a new filtrate, and ethanol is added thereto, and then mechanically stirred, and finally the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a regenerated polyester granular material, and the regenerated polyester granular material is spun to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:40, and the volume of the ethanol is more than 5 times the volume of the new filtrate;

[0233] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 9wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 100°C for 50 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:40; and the process parameters of the spinning process include: a spinning temperature of 100°C, a spinning speed of 80m / min, and a draft ratio of 1:4.

[0234] Tests show that the b value of the recycled polyester granules is 12 and the L value is 78; the dry breaking strength of the regenerated cellulose fiber is 3.1 cN / dtex, the dry breaking elongation is 15%, and the wet breaking strength is 2.1 cN / dtex.

[0235] Embodiment 14

[0236] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0237] (1) Preparation of materials;

[0238] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2600; the polyester fiber content is 50wt%, the material of polyester fiber is PET / PLA (the mass ratio of PET to PLA is 80:20), the polymerization degree of PET is 100, and the polymerization degree of PLA is 200;

[0239] First solvent: a mixture of NMP and HMPA in a mass ratio of 7:3;

[0240] Decolorizing agent: activated carbon, manufactured by Aladdin Company, product number C112241;

[0241] Ethanol;

[0242] Second solvent: NMMO aqueous solution with a concentration of 80wt%;

[0243] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 190°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 200 r / min for 30 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 120 minutes to reduce the polymerization degree of the cotton fiber to 830. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:5;

[0244] (3) Treat the filtrate and filter cake separately;

[0245] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 90° C. for 40 minutes, then filtering the system after the reaction, collecting a new filtrate, adding ethanol thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, and then drying and granulating in sequence to obtain a regenerated polyester granule, and spinning the regenerated polyester granule to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:35, and the volume of the ethanol is more than 5 times the volume of the new filtrate;

[0246] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 8wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 90°C for 40 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:35; and the process parameters of the spinning process include: a spinning temperature of 110°C, a spinning speed of 70m / min, and a draft ratio of 1:5.

[0247] Tests show that the b value of the recycled polyester granules is 13 and the L value is 80; the dry breaking strength of the regenerated cellulose fiber is 3.4 cN / dtex, the dry breaking elongation is 12%, and the wet breaking strength is 2.4 cN / dtex.

[0248] Embodiment 15

[0249] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0250] (1) Preparation of materials;

[0251] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2400; the polyester fiber content is 60wt%, the material of polyester fiber is PET / PBS (the mass ratio of PET to PBS is 70:30), the polymerization degree of PET is 150, and the polymerization degree of PBS is 120;

[0252] First solvent: a mixture of NMP and HMPA in a mass ratio of 8:2;

[0253] Decolorizing agent: sodium formaldehyde sulfoxylate;

[0254] Deionized water;

[0255] Second solvent: NMMO aqueous solution with a concentration of 86wt%;

[0256] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 150° C., and the mixture is first stirred at a stirring speed of 150 r / min for 40 min to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 110 min to reduce the polymerization degree of the cotton fiber to 860, and then the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0257] (3) Treat the filtrate and filter cake separately;

[0258] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 70° C. for 30 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, and then drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:30, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0259] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 7wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 70°C for 30 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:30; and the process parameters of the spinning process include: a spinning temperature of 120°C, a spinning speed of 60m / min, and a draft ratio of 1:6.

[0260] Tests show that the b value of the recycled polyester granules is 15 and the L value is 64; the dry breaking strength of the regenerated cellulose fiber is 3.8 cN / dtex, the dry breaking elongation is 10%, and the wet breaking strength is 2.8 cN / dtex.

[0261] Example 16

[0262] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0263] (1) Preparation of materials;

[0264] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2500; the polyester fiber content is 70wt%, the material of polyester fiber is PET / polyarylate (the mass ratio of PET to polyarylate is 80:20), the polymerization degree of PET is 150, and the polymerization degree of polyarylate is 100;

[0265] First solvent: a mixture of NMP and HMPA in a mass ratio of 6:4;

[0266] Decolorizing agent: sodium formaldehyde sulfoxylate;

[0267] Deionized water;

[0268] Second solvent: NMMO aqueous solution with a concentration of 82wt%;

[0269] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 160° C., and the mixture is first stirred at a stirring speed of 100 r / min for 60 min to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 180 min to reduce the polymerization degree of the cotton fiber to 880, and then the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0270] (3) Treat the filtrate and filter cake separately;

[0271] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 80° C. for 30 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:25, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0272] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 6wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 80°C for 20 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:25; and the process parameters of the spinning process include: a spinning temperature of 90°C, a spinning speed of 50m / min, and a draft ratio of 1:3.

[0273] Tests show that the b value of recycled polyester granules is 14 and the L value is 77; the dry breaking strength of regenerated cellulose fiber is 3.7 cN / dtex, the dry breaking elongation is 12%, and the wet breaking strength is 2.8 cN / dtex.

[0274] Embodiment 17

[0275] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0276] (1) Preparation of materials;

[0277] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 3000; the polyester fiber content is 50wt%, the material of polyester fiber is PTT / PLA (the mass ratio of PTT to PLA is 70:30), the polymerization degree of PTT is 80, and the polymerization degree of PLA is 200;

[0278] First solvent: a mixture of NMP and DMSO in a mass ratio of 1:1;

[0279] Decolorizing agent: sodium formaldehyde sulfoxylate;

[0280] Deionized water;

[0281] Second solvent: NMMO aqueous solution with a concentration of 80wt%;

[0282] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 190°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 200 r / min for 5 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 90 minutes to reduce the polymerization degree of the cotton fiber to 870. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:6;

[0283] (3) Treat the filtrate and filter cake separately;

[0284] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, and the reaction is carried out at 100° C. for 50 minutes, and then the system after the reaction is filtered to collect a new filtrate, and deionized water is added thereto, and mechanical stirring is performed, and finally the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a recycled polyester granular material, and the recycled polyester granular material is spun to obtain a recycled polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:50, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0285] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 9wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 100°C for 40 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:50; and the process parameters of the spinning process include: a spinning temperature of 100°C, a spinning speed of 70m / min, and a draft ratio of 1:5.

[0286] Tests show that the b value of recycled polyester granules is 11 and the L value is 76; the dry breaking strength of regenerated cellulose fiber is 3.8 cN / dtex, the dry breaking elongation is 11%, and the wet breaking strength is 2.9 cN / dtex.

[0287] Embodiment 18

[0288] A method for regenerating waste cotton / polyester fiber blended fabric, the specific steps are as follows:

[0289] (1) Preparation of materials;

[0290] Waste cotton / polyester fiber blended fabric: the polymerization degree of cotton fiber is 2300; the polyester fiber content is 50wt%, the material of polyester fiber is PBT / PLA (the mass ratio of PBT to PLA is 60:40), the polymerization degree of PBT is 120, and the polymerization degree of PLA is 200;

[0291] First solvent: a mixture of NMP and DMSO in a mass ratio of 2:1;

[0292] Decolorizing agent: sodium formaldehyde sulfoxylate;

[0293] Deionized water;

[0294] Second solvent: NMMO aqueous solution with a concentration of 85wt%;

[0295] (2) After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the pressure is always maintained at 0.1 MPa and the temperature is 140°C. The waste cotton / polyester fiber blended fabric is first stirred at a stirring speed of 150 r / min for 30 minutes to completely dissolve the polyester fiber in the waste cotton / polyester fiber blended fabric, and then stirred at the same stirring speed for 120 minutes to reduce the polymerization degree of the cotton fiber to 840. Subsequently, the filtrate and the filter cake are separated; wherein the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:5;

[0296] (3) Treat the filtrate and filter cake separately;

[0297] The treatment process of the filtrate is as follows: first, a decolorizing agent is added to the filtrate, reacting at 90° C. for 60 minutes, then filtering the system after the reaction, collecting a new filtrate, adding deionized water thereto, mechanically stirring, and finally filtering the new filtrate, collecting the filter cake, drying and granulating in sequence to obtain a regenerated polyester granular material, and spinning the regenerated polyester granular material to obtain a regenerated polyester fiber; wherein the mass ratio of the decolorizing agent to the filtrate is 1:40, and the volume of the deionized water is more than 5 times the volume of the new filtrate;

[0298] The filter cake treatment process is as follows: after dissolving the filter cake in a second solvent to obtain a first regenerated cellulose solution with a concentration of 7wt%, a decolorizing agent is added to the first regenerated cellulose solution, reacting at 80°C for 50 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, and spinning the second regenerated cellulose solution to obtain regenerated cellulose fibers; wherein the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:40; and the process parameters of the spinning process include: a spinning temperature of 110°C, a spinning speed of 80m / min, and a draft ratio of 1:4.

[0299] Tests show that the b value of recycled polyester granules is 12 and the L value is 78; the dry breaking strength of regenerated cellulose fiber is 3.4 cN / dtex, the dry breaking elongation is 13%, and the wet breaking strength is 2.3 cN / dtex.

Claims

1. A method for regenerating waste cotton / polyester fiber blended fabric, characterized in that: After mixing the waste cotton / polyester fiber blended fabric and the first solvent, the mixture is kept warm under the conditions of a pressure of 0.1 MPa and a temperature of T with stirring until the polyester fiber in the waste cotton / polyester fiber blended fabric is completely dissolved and the polymerization degree of the cotton fiber is reduced to 700-950, the filtrate and the filter cake are separated, the filtrate is treated to obtain regenerated polyester, and the filter cake is treated to obtain regenerated cellulose fiber; The polyester fiber content in the waste cotton / polyester fiber blended fabric is 10-90wt%, and the mass ratio of the waste cotton / polyester fiber blended fabric to the first solvent is 1:4-10; The first solvent is NMP, DMF, DMAc, HMPA or DMSO; or, the first solvent is a mixture of NMP and DMAc, the mass ratio of NMP to DMAc is 1:1, 2:1 or 3:1; or, the first solvent is a mixture of NMP and HMPA, the mass ratio of NMP to HMPA is 7:3, 8:2 or 6:4; or, the first solvent is a mixture of NMP and DMSO, the mass ratio of NMP to DMSO is 1:1 or 2:1; T is 130-190℃.

2. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 1, characterized in that: The initial polymerization degree of cotton fiber in the waste cotton / polyester fiber blended fabric is 1500-3000, and the polymerization degree of polyester fiber is 100-200; The total insulation time is t2. When the insulation reaches t1, the polyester fiber in the waste cotton / polyester fiber blended fabric is completely dissolved. <t2; When the first solvent is NMP, T is 130-190°C, t1 is 5-30min, 30min <t2<190min; When the first solvent is DMF, T is 130-150°C, t1 is 15-30min, 110min <t2<190min; When the first solvent is DMAc, T is 140-160°C, t1 is 10-30min, 170min <t2<250min; When the first solvent is HMPA, T is 150-180°C, t1 is 30-60min, 200min <t2<250min; When the first solvent is DMSO, T is 150-170℃, t1 is 5-15min, 160min <t2<190min; When the first solvent is a mixture of NMP and DMAc, T is 140-190°C, t1 is 5-30min, 20min <t2<220min; When the first solvent is a mixture of NMP and HMPA, T is 150-190°C, t1 is 30-60min, 140min <t2<250min; When the first solvent is a mixture of NMP and DMSO, T is 140-190°C, t1 is 5-30min, 90min <t2<180min。 3. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 1, characterized in that: The stirring speed is 50-300r / min.

4. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 1, characterized in that: The material of the polyester fiber in the waste cotton / polyester fiber blended fabric is one or more of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, polybutylene succinate and polyarylate.

5. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 1, characterized in that: The specific process of treating the filtrate to obtain the recycled polyester is as follows: first, a decolorizing agent is added to the filtrate, and the reaction is carried out at 60-100°C for 30-80 minutes. Then, the system after the reaction is filtered, and a new filtrate is collected, and deionized water or ethanol is added thereto, and mechanical stirring is performed. Finally, the new filtrate is filtered, and after the filter cake is collected, it is dried and granulated in sequence to obtain a recycled polyester granular material with a b value ≤16 and an L value ≥60.

6. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 5, characterized in that: The decolorizing agent is one or more of sodium hypochlorite, hydrogen peroxide, activated carbon and sodium formaldehyde sulfoxylate, and the mass ratio of the decolorizing agent to the filtrate is 1:20-50; the volume of deionized water or ethanol is more than 5 times the volume of the new filtrate.

7. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 5, characterized in that: The recycled polyester granules are also spun to obtain recycled polyester fibers.

8. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 1, characterized in that: The process of treating the filter cake to obtain regenerated cellulose fiber is as follows: dissolving the filter cake in a second solvent NMMO aqueous solution to obtain a first regenerated cellulose solution, adding a decolorizing agent to the first regenerated cellulose solution, reacting at 60-110° C. for 15-80 minutes, filtering the system after the reaction, collecting a transparent and colorless second regenerated cellulose solution, spinning the second regenerated cellulose solution to obtain regenerated cellulose fiber, wherein the concentration of the NMMO aqueous solution is 80-86wt%.

9. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 8, characterized in that: The concentration of the first regenerated cellulose solution is 6-10wt%; the decolorizing agent is one or more of sodium hypochlorite, hydrogen peroxide, activated carbon and sodium formaldehyde sulfoxylate, and the mass ratio of the decolorizing agent to the first regenerated cellulose solution is 1:10-50.

10. The method for regenerating waste cotton / polyester fiber blended fabric according to claim 8, characterized in that: The process parameters of the spinning process include: spinning temperature 90-120°C, spinning speed 40-90m / min, and draft ratio 1:3-6; the dry breaking strength of the regenerated cellulose fiber is 3-4cN / dtex, the dry breaking elongation is 10-15%, and the wet breaking strength is 2-3cN / dtex.