Method for preparing regenerated cellulose fiber / film by separating waste polyester-cotton with phosphate ester ionic liquid

Abstract

The application provides a method for recycling waste polyester-cotton fabric to prepare regenerated cellulose fiber / film by using phosphate ester ionic liquid, which comprises the following steps: mixing phosphate ester ionic liquid with a cosolvent and pretreated polyester-cotton, and dissolving at a certain temperature; the obtained product is vacuum degassed and filtered, the filtrate is used to prepare regenerated cellulose fiber / film, the remaining fabric after filtration is washed by using the cosolvent or phosphate ester ionic liquid and water, and the phosphate ester ionic liquid and the cosolvent used in the separation process can be recycled. The operation method is simple, the solvents can be recycled, the polyester-cotton dissolution rate is 90.0-99.9%, the breaking strength of the obtained regenerated cellulose fiber is 1.0-2.3 cN / dtex, the elongation rate is 5%-17%, the longitudinal tensile strength of the regenerated cellulose film is 20-27 N / mm, and the transverse tensile strength is 10-17 N / mm.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of recycling and utilization of waste textiles, and particularly relates to a method for preparing regenerated cellulose fiber / regenerated cellulose film by separating waste polyester-cotton using phosphate ester ionic liquid. BACKGROUND

[0002] Polyester-cotton refers to the general term of polyester (polyethylene terephthalate, PET) and cotton blended fabric, and is a textile woven by 65%-67% polyester and 35%-33% cotton, commonly known as "Dekal", which is a commonly used material for making clothes. With the economic development and the continuous growth of population, the global textile production is increasing year by year, and the annual fiber production of the world was about 110 million tons in 2020, thus the pressure of waste textiles on the environment is also increasing. Since the 1980s, the recycling of waste textiles has been valued by some textile industrialized countries, and China also began the corresponding research in the 1990s. In 2020, the total production of waste textiles in China was about 30 million tons, and it is still increasing at a rate of 10% per year, among which the proportion of polyester-cotton fabric is as high as 76%, but its recycling rate is only less than 15%, and a large amount of waste textiles are buried and burned as garbage, causing a large amount of carbon dioxide emission and serious resource waste and environmental pollution. In addition, according to the research of the International Recycling Bureau: every 1 kg of waste textiles recycled can reduce 3.6 kg of CO2 emission, save 6000 liters of water, and reduce the use of 0.3 kg of chemical fertilizer and 0.2 kg of pesticide. Reducing CO2 emission level, improving energy utilization efficiency and building a green and low-carbon circular development economic system have become the main goal of national economic and social development. Therefore, the realization of large-scale and efficient recycling of waste textiles in the textile industry has important practical and social significance for relieving resource shortage and energy saving and emission reduction.

[0003] The recycling of waste polyester-cotton fabric is mainly through the degradation or dissolution of one component in polyester-cotton fabric. One method is to alcoholysis, ammonolysis or hydrolysis of polyester in waste polyester-cotton, and the cotton fiber component is retained, but these methods usually require high temperature and high pressure conditions, and the equipment requirements are higher. Another method is to degrade or dissolve the cotton fiber in waste polyester-cotton, and the polyester component is retained. In Chinese patent CN102199310A, N-methylmorpholine-N-oxide (NMMO) is used to dissolve the cotton fiber in waste polyester-cotton, and the polyester-cotton separation is realized, but this method has problems such as high viscosity of cellulose solution, difficult separation and serious degradation of regenerated cellulose. In recent years, ionic liquids have been rapidly developed as efficient and green solvents. Compared with other ordinary organic solvents, ionic liquids exhibit a series of excellent properties: almost no vapor pressure, structure can be designed, good thermal stability, etc., which not only effectively avoids the environmental pollution caused by the volatilization of ordinary organic solvents during use. In Chinese patent CN104130425A, carboxylic acid type ionic liquid and auxiliary solvent are used to prepare regenerated cellulose material, which significantly improves the toughness of the regenerated cellulose product, but the synthesis method of acetate ionic liquid is relatively complex and the stability is relatively poor; in CN106146877A, ionic liquids with halogen and acetate anions and water are used to selectively dissolve the cotton fiber component under vacuum and recover polyester and cotton, but the halogen ionic liquid in the patent has great corrosion to the equipment and the regenerated cellulose obtained is seriously degraded. At the same time, after the ionic liquid dissolves the waste polyester-cotton, the cellulose solution generally has the problems of high viscosity and difficult separation from polyester. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a method for recycling waste polyester-cotton to prepare regenerated cellulose fiber / film using phosphate ester ionic liquid, which uses phosphate ester ionic liquid and co-solvent with simple synthesis method, good stability and low viscosity to efficiently dissolve cotton fiber under normal pressure while reducing the viscosity of the cellulose solution, and obtain slightly degraded regenerated cellulose, which makes up for the shortcomings of using ionic liquid in the prior art and solves the problems of difficult separation of cellulose solution from polyester and serious degradation of regenerated cellulose.

[0005] To solve the above technical problems, the present application adopts the following technical scheme:

[0006] A method for recycling waste polyester-cotton to prepare regenerated cellulose fiber / film using phosphate ester ionic liquid, comprising the following steps:

[0007] (1) The waste polyester-cotton is pretreated by disinfection, decolorization, drying, crushing and the like;

[0008] (2) mixing the pretreated polyester-cotton raw material with the phosphate ester ionic liquid or mixing the pretreated polyester-cotton raw material with the phosphate ester ionic liquid and a cosolvent, and performing polyester-cotton dissolution separation under certain conditions;

[0009] (3) filtering the mixture obtained in step (2) to obtain a cellulose solution, vacuum degassing the cellulose solution, and preparing regenerated cellulose fibers by dry jet-wet spinning or preparing a cellulose film by a casting method;

[0010] (4) washing the remaining fabric obtained by filtering in step (3) with a cosolvent or the phosphate ester ionic liquid and water, and using the washed and dried remaining fabric as raw material for industrial production, and using the cosolvent or the phosphate ester ionic liquid used for flushing as a solvent for separating waste polyester-cotton fabric.

[0011] Further, the polymerization degree of the cotton fiber in the waste polyester-cotton in step (1) is 300-1000, and the molecular weight of the polyester in the waste polyester-cotton is 15000-23000.

[0012] Further, the pretreatment method in step (1) includes first disinfecting and decolorizing the waste polyester-cotton fabric, mixing it with 20-50 g / L of hydrogen peroxide or sodium hypochlorite, a solid-liquid mass ratio of 1:(10-30), a treatment temperature of 50-90℃, and a treatment time of 15-80 min, and drying the treated polyester-cotton fabric at a temperature of 80-100℃ for 3-6 h. The crushed polyester-cotton fabric is in the form of blocks with a size of 0.2-1.5 cm 2 .

[0013] Further, the phosphate ester ionic liquid in step (2) is any one or a combination of at least two of 1-R2-3-R1-imidazole dimethyl (or ethyl, butyl) phosphate, 1-R2-1,5-diazabicyclo[4.3.0]-5-nonene dimethyl (or ethyl, butyl) phosphate, wherein R1=C n H 2n+1 , n is 1-8, R2=C m H 2m+1 , m is 1-8 (n and m are positive integers).

[0014] Further, the phosphate ester ionic liquid in step (2) is 1-ethyl-3-methyl imidazole diethyl phosphate, 1-ethyl-3-methyl imidazole dimethyl phosphate, 1,5-diazabicyclo[4.3.0]non-5-ene diethyl phosphate, and 1,3-diethyl imidazole diethyl phosphate, etc.

[0015] Further, the cosolvent in step (2) includes DMSO and DMF.

[0016] Further, the mass ratio of the pretreated polyester-cotton raw material and the phosphate ester ionic liquid in the step (2) is (0.1-0.3):(1-5), and the mass ratio of the pretreated polyester-cotton raw material, the phosphate ester ionic liquid and the cosolvent in the step (2) is (0.1-0.3):(1-5):1.

[0017] Further, the dissolution temperature in the step (2) is 60-110 DEG C, the dissolution time is 3-6 h, and the mechanical stirring speed is 80-150 r / min.

[0018] Further, the dissolution rate of the polyester-cotton in the step (2) reaches 90.0-99.9%, and the degradation rate of the regenerated cellulose is about 2-10%.

[0019] Further, the breaking strength of the regenerated cellulose fiber is 1.0-2.3 cN / dtex, the elongation is 5%-17%, the longitudinal tensile strength of the regenerated cellulose film is 20-27 N / mm, and the transverse tensile strength is 10-17 N / mm.

[0020] The waste polyester-cotton is pretreated, mixed with the phosphate ester ionic liquid and the cosolvent in a certain proportion, and the cotton fiber in the raw material is dissolved under certain conditions, and then filtered, washed and dried, so as to realize the separation of the polyester and the cotton in the waste raw material, the separation process is simple, and the pollution to the environment is avoided. The cosolvent is used in the dissolution process, which can promote the swelling of the cotton fiber on the one hand, and reduce the viscosity of the phosphate ester ionic liquid on the other hand, so that the phosphate ester ionic liquid can fully contact with the polyester-cotton raw material, significantly improve the dissolution rate of the cotton, and make the polyester and the cellulose solution easy to separate, the dissolution and separation process does not need to add negative pressure, and the polyester-cotton separation can be realized in a green and low-energy consumption manner. In addition, the phosphate ester ionic liquid and the cosolvent solution can be recycled.

[0021] The phosphonate ionic liquid has the advantages of simple synthesis, good stability, small viscosity, small corrosion to equipment and high cellulose dissolution efficiency. The cotton dissolution rate reaches 90.0-99.9%, and the polyester cotton separation can be more efficiently realized. 2. The regenerated cellulose obtained by the phosphonate ionic liquid has small degradation and basically has no influence on the polyester. The degradation rate of halogen ionic liquid on cellulose is about 25%, and the degradation rate of phosphonate ionic liquid on cellulose is 2-10%. The phosphonate ionic liquid can significantly reduce the degradation of cellulose. 3. The phosphonate ionic liquid or the phosphonate ionic liquid and the cosolvent are used as the solvent to separate the cellulose in the polyester cotton, and then the dry spraying-wet spinning method is used to prepare the regenerated fiber, or the casting method is used to prepare the cellulose film, which has the advantages of green environmental protection, solvent recyclability, easy industrialization and the like. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a polarizing microscope photo of the polyester cotton raw material in the embodiment 5 of the present application.

[0023] Figure 2 It is a photo of the residual polyester after the phosphonate ionic liquid / cosolvent separates the polyester cotton in the embodiment 5 of the present application.

[0024] Figure 3 It is a polarizing microscope photo of the phosphonate ionic liquid / cosolvent-cellulose solution in the embodiment 5 of the present application. DETAILED DESCRIPTION

[0025] The technical solutions of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by the ordinary skilled in the art without creative labor are within the protection scope of the present application.

[0026] Embodiment 1

[0027] The method for recycling waste polyester cotton to prepare regenerated cellulose by using the phosphonate ionic liquid in the embodiment comprises the following steps:

[0028] (1) The recycled waste polyester cotton fabric (polyester 65% / cotton 35%, the polymerization degree of cotton is 1000, and the molecular weight of PET is 20000) is pretreated through disinfection, decolorization, drying and crushing processes. The specific method is as follows: the waste polyester cotton fabric is mixed with 40 g / L of hydrogen peroxide or sodium hypochlorite and water, the solid-liquid mass ratio is 1:10:10, the treatment temperature is 60℃, the treatment time is 60 min, the treated polyester cotton fabric is dried at 100℃ for 6 h, and finally crushed into 1cm 2 blocks.

[0029] (2) Take 0.4 g of pretreated waste polyester-cotton raw material and 10 g of 1-ethyl-3-methylimidazole dimethyl phosphate, mix them, and dissolve them at a temperature of 80 ℃ and a mechanical stirring speed of 120 r / min for 5 h;

[0030] (3) After the end, separate the glue solution from the remaining filament, rinse the filtered filament with the phosphate ester ionic liquid and water in turn, and dry to obtain regenerated polyester. The cellulose solution is prepared into regenerated cellulose fiber through a dry-jet wet spinning device, and then wound into a cylinder after a coagulation bath, washing, drying, and other steps, or the cellulose solution is prepared into a cellulose film by a casting method. The dissolution rate of cotton in the polyester-cotton raw material is 98.9%.

[0031] Through testing, the degradation rate of the prepared regenerated cellulose is about 3%, the breaking strength of the regenerated cellulose fiber is 1.68 cN / dtex, and the elongation rate is 11.2%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.5 N / mm, and the transverse tensile strength reaches 15.7 N / mm.

[0032] Example 2

[0033] The method for preparing regenerated cellulose by recycling waste polyester-cotton using a phosphate ester ionic liquid in this embodiment includes the following steps:

[0034] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the polymerization degree of cotton is 1000, and the molecular weight of PET is 20000) is pretreated through disinfection, decolorization, drying, and crushing processes; the specific method is the same as that in Example 1;

[0035] (2) Take 0.4 g of pretreated waste polyester-cotton raw material and 10 g of 1-ethyl-3-methylimidazole dimethyl phosphate, mix them, and dissolve them at a temperature of 80 ℃ and a mechanical stirring speed of 120 r / min for 5 h;

[0036] (3) After the end, separate the glue solution from the remaining filament, rinse the filtered filament with the phosphate ester ionic liquid and water in turn, and dry to obtain regenerated polyester. The cellulose solution is prepared into regenerated cellulose fiber through a dry-jet wet spinning device, and then wound into a cylinder after a coagulation bath, washing, drying, and other steps, or the cellulose solution is prepared into a cellulose film by a casting method. The dissolution rate of cotton in the polyester-cotton raw material is 98.9%.

[0037] Through testing, the degradation rate of the prepared regenerated cellulose is about 3%, the breaking strength of the regenerated cellulose fiber is 1.68 cN / dtex, and the elongation rate is 11.2%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.5 N / mm, and the transverse tensile strength reaches 15.7 N / mm.

[0038] Example 3

[0039] The method for preparing regenerated cellulose from waste polyester-cotton fabric using phosphate ester ionic liquid in this example comprises the following steps:

[0040] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the degree of polymerization of cotton is 1000, and the molecular weight of PET is 20000) was pretreated by disinfection, decolorization, drying, and crushing. The specific method was the same as that in Example 1.

[0041] (2) 0.4 g of the pretreated waste polyester-cotton fabric and 10 g of 1,3-diethylimidazole diethyl phosphate were mixed, and dissolved at 80°C under mechanical stirring at a speed of 120 r / min for 5 h;

[0042] (3) After the end, the glue solution was separated from the remaining filament, and the filtered filament was rinsed with phosphate ester ionic liquid and water in sequence and dried to obtain regenerated polyester. The cellulose solution was prepared into regenerated cellulose fiber by a dry-jet wet spinning device, and then wound into a cylinder after coagulation bath, washing, and drying. Or the cellulose solution was prepared into a cellulose film by a casting method. The dissolution rate of cotton in the polyester-cotton fabric was 95.3%.

[0043] Through testing, the degradation rate of the prepared regenerated cellulose was about 6%, the breaking strength of the regenerated cellulose fiber was 1.58 cN / dtex, and the elongation rate was 11.6%. The longitudinal tensile strength of the regenerated cellulose film reached 24.5 N / mm, and the transverse tensile strength reached 15.0 N / mm.

[0044] Example 4

[0045] The method for preparing regenerated cellulose from waste polyester-cotton fabric using phosphate ester ionic liquid in this example comprises the following steps:

[0046] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the degree of polymerization of cotton is 1000, and the molecular weight of PET is 20000) was pretreated by disinfection, decolorization, drying, and crushing. The specific method was the same as that in Example 1.

[0047] (2) 0.4 g of the pretreated waste polyester-cotton fabric and 10 g of 1,3-diethylimidazole diethyl phosphate were mixed, and dissolved at 80°C under mechanical stirring at a speed of 120 r / min for 5 h;

[0048] (3) After the end, the glue solution is separated from the remaining filament bundle, the filtered filament bundle is washed with the phosphonate ionic liquid and water in sequence, and is dried to obtain regenerated polyester, the cellulose solution is prepared into regenerated cellulose fiber through a dry spraying wet spinning device, and after the steps of coagulation bath, washing, drying, etc., it is wound into a cylinder, or the cellulose solution is prepared into a cellulose film by a flow casting method. The dissolution rate of cotton in the polyester-cotton raw material is 95.6%.

[0049] Through testing, the degradation rate of the prepared regenerated cellulose is about 7%, the breaking strength of the regenerated cellulose fiber is 1.53 cN / dtex, and the elongation rate is 11.8%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.1 N / mm, and the transverse tensile strength reaches 15.1 N / mm.

[0050] Example 5

[0051] The method for preparing regenerated cellulose by recycling waste polyester-cotton in the embodiment by using the phosphonate ionic liquid comprises the following steps:

[0052] (1) The recycled waste polyester-cotton fabric (polyester 65% and cotton 35%, the polymerization degree of cotton is 1000, and the molecular weight of PET is 20000) is pretreated through disinfection, decolorization, drying, and crushing processes; the specific method is as follows: the waste polyester-cotton fabric is mixed with 40 g / L of hydrogen peroxide or sodium hypochlorite and water, the solid-liquid mass ratio is 1:10:10, the treatment temperature is 60 ℃, the treatment time is 60 min, the treated polyester-cotton fabric is dried at 100 ℃ for 6 h, and finally crushed into 1 cm 2 blocks.

[0053] (2) 0.4 g of the pretreated waste polyester-cotton raw material is mixed with 10 g of the cosolvent DMSO and 10 g of 1-ethyl-3-methylimidazole diethyl phosphate under the conditions of a temperature of 80 ℃ and a mechanical stirring speed of 120 r / min for 5 h of dissolution;

[0054] (3) After the end, the glue solution is separated from the remaining filament bundle, the filtered filament bundle is washed with the phosphonate ionic liquid and water in sequence, and is dried to obtain regenerated polyester, the cellulose solution is prepared into regenerated cellulose fiber through a dry spraying wet spinning device, and after the steps of coagulation bath, washing, drying, etc., it is wound into a cylinder, or the cellulose solution is prepared into a cellulose film by a flow casting method. The dissolution rate of cotton in the polyester-cotton raw material is 95.6%.

[0055] Through testing, the degradation rate of the prepared regenerated cellulose is about 7%, the breaking strength of the regenerated cellulose fiber is 1.53 cN / dtex, and the elongation rate is 11.8%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.1 N / mm, and the transverse tensile strength reaches 15.1 N / mm.

[0056] Example 6

[0057] The method for preparing regenerated cellulose from waste polyester-cotton fabric by using phosphate ester ionic liquid in the embodiment comprises the following steps:

[0058] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the degree of polymerization of cotton is 1000, and the molecular weight of PET is 20000) is pretreated through disinfection, decolorization, drying and crushing processes; the specific method is the same as that in Example 1;

[0059] (2) 0.4 g of the pretreated waste polyester-cotton raw material, 10 g of the cosolvent DMF and 10 g of 1-ethyl-3-methylimidazole dimethyl phosphate are taken, and the mixture is dissolved at 80 ℃ and a mechanical stirring speed of 120 r / min for 5 h;

[0060] (3) After the end, the glue solution is separated from the remaining filament, the filtered filament is washed with the cosolvent and water in sequence and dried to obtain regenerated polyester, the cellulose solution is prepared into regenerated cellulose fiber through a dry-jet wet spinning device, and after the steps of coagulation bath, washing and drying, the regenerated cellulose fiber is wound into a cylinder, or the cellulose solution is prepared into a cellulose film by a casting method. The dissolution rate of cotton in the polyester-cotton raw material is 97.9%.

[0061] Through testing, the degradation rate of the prepared regenerated cellulose is about 2%, the breaking strength of the regenerated cellulose fiber is 1.68 cN / dtex, and the elongation rate is 16.4%; the longitudinal tensile strength of the regenerated cellulose film reaches 24.9 N / mm, and the transverse tensile strength reaches 14.8 N / mm.

[0062] Example 7

[0063] The method for preparing regenerated cellulose from waste polyester-cotton fabric by using phosphate ester ionic liquid in the embodiment comprises the following steps:

[0064] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the degree of polymerization of cotton is 1000, and the molecular weight of PET is 20000) is pretreated through disinfection, decolorization, drying and crushing processes; the specific method is the same as that in Example 1;

[0065] (2) 0.4 g of the pretreated waste polyester-cotton raw material and 5 g of the cosolvent DMSO and 10 g of 1,3-diethyl imidazole diethyl phosphate are mixed, and the mixture is dissolved at 80 ℃ and a mechanical stirring speed of 120 r / min for 5 h;

[0066] (3) After the end, the glue solution is separated from the remaining filament bundle, the filtered filament bundle is washed with a common solvent and water in sequence and dried to obtain regenerated polyester, the cellulose solution is prepared into regenerated cellulose fiber through a dry spraying wet spinning device, and after going through steps such as a coagulation bath, washing and drying, the regenerated cellulose fiber is wound into a bobbin, or the cellulose solution is prepared into a cellulose film by using a flow casting method. The dissolution rate of cotton in the cotton-polyester raw material is 99.5%.

[0067] Through testing, the degradation rate of the prepared regenerated cellulose is about 5%, the breaking strength of the regenerated cellulose fiber is 1.48 cN / dtex, and the elongation rate is 14.3%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.2 N / mm, and the transverse tensile strength reaches 15.7 N / mm.

[0068] Example 8

[0069] The method for preparing regenerated cellulose by recycling waste polyester-cotton in the embodiment of the application by using phosphate ester ionic liquid comprises the following steps:

[0070] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the polymerization degree of cotton is 1000, and the molecular weight of PET is 20000) is pretreated through disinfection, decolorization, drying and crushing processes; the specific method is the same as that in Example 1;

[0071] (2) 0.4 g of the pretreated waste polyester-cotton raw material and 10 g of a common solvent DMSO and 10 g of diethyl 1,5-diazabicyclo[4.3.0]non-5-ene phosphate are mixed, and dissolved at a temperature of 80 ℃ and a mechanical stirring speed of 120 r / min for 5 h;

[0072] (3) After the end, the glue solution is separated from the remaining filament bundle, the filtered filament bundle is washed with a common solvent and water in sequence and dried to obtain regenerated polyester, the cellulose solution is prepared into regenerated cellulose fiber through a dry spraying wet spinning device, and after going through steps such as a coagulation bath, washing and drying, the regenerated cellulose fiber is wound into a bobbin, or the cellulose solution is prepared into a cellulose film by using a flow casting method. The dissolution rate of cotton in the cotton-polyester raw material is 96.7%.

[0073] Through testing, the degradation rate of the prepared regenerated cellulose is about 5%, the breaking strength of the regenerated cellulose fiber is 1.52 cN / dtex, and the elongation rate is 13.2%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.5 N / mm, and the transverse tensile strength reaches 15.7 N / mm.

[0074] Example 9

[0075] The method for preparing regenerated cellulose by recycling waste polyester-cotton in the embodiment of the application by using phosphate ester ionic liquid comprises the following steps:

[0076] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the degree of polymerization of cotton is 1000, and the molecular weight of PET is 20000) is subjected to disinfection, decolorization, drying, and crushing processes; the specific method is the same as in Example 1.

[0077] (2) 0.4 g of the waste polyester-cotton raw material and 10 g of 1-ethyl-3-methylimidazole diethyl phosphate are mixed, and dissolved at a temperature of 80 °C and a mechanical stirring speed of 120 r / min for 5 h;

[0078] (3) After the end, the glue solution is separated from the remaining filament, and the filtered filament is washed with the phosphate ester ionic liquid and water in sequence and dried to obtain regenerated polyester, and the cellulose solution is prepared into regenerated cellulose fiber through a dry-jet wet spinning device, and then wound into a cylinder after coagulation bath, washing, and drying, or the cellulose solution is prepared into a cellulose film by a flow casting method.

[0079] (4) The coagulation bath obtained in the process is rotary evaporated and dried to obtain recycled 1-ethyl-3-methylimidazole diethyl phosphate, and the recycled phosphate ester ionic liquid is subjected to a dissolution experiment under the above conditions again, and the dissolution rate of cotton in the polyester-cotton raw material is 98.8%.

[0080] Through testing, the degradation rate of the prepared regenerated cellulose is about 3%, the breaking strength of the regenerated cellulose fiber is 1.70 cN / dtex, and the elongation rate is 12.6%; the longitudinal tensile strength of the regenerated cellulose film reaches 24.6 N / mm, and the transverse tensile strength reaches 14.7 N / mm.

[0081] Example 10

[0082] The method for preparing regenerated cellulose from recycled waste polyester-cotton by using a phosphate ester ionic liquid in this example comprises the following steps:

[0083] (1) The recycled waste polyester-cotton fabric (polyester 65% / cotton 35%, the degree of polymerization of cotton is 1000, and the molecular weight of PET is 20000) is subjected to disinfection, decolorization, drying, and crushing processes; the specific method is the same as in Example 1;

[0084] (2) 0.4 g of the waste polyester-cotton raw material and 10 g of 1-ethyl-3-methylimidazole diethyl phosphate are mixed, and dissolved at a temperature of 80 °C and a mechanical stirring speed of 120 r / min for 5 h;

[0085] (3) After the end, the glue solution is separated from the remaining tow, the filtered tow is washed with a co-solvent and water in turn and dried to obtain regenerated polyester, the cellulose solution is prepared into regenerated cellulose fiber by a dry-jet wet spinning device, and after a coagulation bath, washing, drying and other steps, it is wound into a cylinder, or the cellulose solution is prepared into a cellulose film by a casting method.

[0086] (4) The coagulation bath obtained in the process is rotary evaporated and dried to obtain recovered 1-ethyl-3-methylimidazole diethyl phosphate and a co-solvent, the ratio of the two is adjusted, and the recovered solvent is re-dissolved under the above conditions, and the dissolution rate of cotton in the polyester-cotton raw material is 99.7%.

[0087] Through testing, the degradation rate of the prepared regenerated cellulose is about 5%, the breaking strength of the regenerated cellulose fiber is 1.76 cN / dtex, and the elongation rate is 16.2%; the longitudinal tensile strength of the regenerated cellulose film reaches 25.4 N / mm, and the transverse tensile strength reaches 15.6 N / mm.

[0088] Comparative Example 1

[0089] On the basis of Example 1, the ionic liquid in Example 1 is replaced with 1-allyl-3-methylimidazole chloride salt, and the remaining implementation is the same as Example 1, and performance testing is performed, and the results are shown in Table 1.

[0090] Table 1 Performance test of ion liquid separation of waste polyester-cotton to prepare regenerated cellulose fiber / film in Example 1 and Comparative Example 1

[0091]

[0092] Comparative Example 2

[0093] On the basis of Example 5, the ionic liquid in Example 5 is replaced with 1-allyl-3-methylimidazole chloride salt, and the remaining implementation is the same as Example 5, and performance testing is performed, and the results are shown in Table 2.

[0094] Table 2 Performance test of ion liquid separation of waste polyester-cotton to prepare regenerated cellulose fiber / film in Example 5 and Comparative Example 2

[0095]

[0096] The above only describes the preferred embodiments of the present application and does not limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids, characterized in that... Includes the following steps: (1) The waste polyester cotton is disinfected, decolorized, dried and crushed in sequence for pretreatment; (2) Mix the pretreated polyester-cotton raw material with a phosphate ester ionic liquid or mix the pretreated polyester-cotton raw material with a phosphate ester ionic liquid and a co-solvent, and then dissolve and separate the polyester-cotton under mechanical stirring conditions; (3) Filter the mixture obtained in step (2), and degas the resulting cellulose solution under vacuum. Prepare regenerated cellulose fibers by dry-spray-wet spinning, or prepare cellulose films by casting. (4) The remaining fabric obtained from filtration in step (3) is washed with a co-solvent or phosphate ester ionic liquid and water. After washing and drying, the remaining fabric is used as raw material for industrial production. The co-solvent or phosphate ester ionic liquid used for rinsing is used for the separation of waste polyester-cotton fabric.

2. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: In step (1), the degree of polymerization of cotton fibers in waste polyester-cotton is 300~1000, and the molecular weight of polyester in polyester-cotton is 15000~23000.

3. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: The pretreatment method in step (1) includes disinfecting and decolorizing the waste polyester-cotton fabric, mixing it with 20-50 g / L hydrogen peroxide or sodium hypochlorite at a solid-liquid mass ratio of 1:(10-30), treating it at a temperature of 50-90 ℃ for 15-80 min, drying the treated polyester-cotton fabric at 80-100 ℃ for 3-6 h, and pulverizing the polyester-cotton fabric to a thickness of 0.2-1.5 cm. 2 Blocky.

4. The method for preparing regenerated cellulose fibers / membranes by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: The phosphate ester ionic liquid is any one or more of 1-R2-3-R1-imidazolium dimethyl phosphate, 1-R2-3-R1-imidazolium diethyl phosphate, 1-R2-3-R1-imidazolium dibutyl phosphate, 1-R2-1,5-diazabicyclo[4.3.0]-5-nonene dimethyl phosphate, 1-R2-1,5-diazabicyclo[4.3.0]-5-nonene diethyl phosphate, and 1-R2-1,5-diazabicyclo[4.3.0]-5-nonene dibutyl phosphate, wherein R1 = C n H 2n+1 n takes values ​​from 1 to 8, R² = C m H 2m+1 m takes values ​​from 1 to 8, and n and m are both positive integers.

5. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 4, characterized in that: The phosphate ester ionic liquid is 1-ethyl-3-methylimidazolium phosphate diethyl ester, 1-ethyl-3-methylimidazolium phosphate dimethyl ester, 1,5-diazabicyclo[4.3.0]-5-nonene phosphate diethyl ester or 1,3-diethylimidazolium phosphate diethyl ester.

6. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: The solvents used in step (2) include DMSO and DMF.

7. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: In step (2), when the pretreated polyester-cotton raw material is mixed with the phosphate ester ionic liquid, the mass ratio of the polyester-cotton raw material to the phosphate ester ionic liquid is (0.1~0.3):(1~5). In step (2), when the pretreated polyester-cotton raw material is mixed with the phosphate ester ionic liquid and the co-solvent, the mass ratio of the polyester-cotton raw material to the phosphate ester ionic liquid and the co-solvent is (0.1~0.3):(1~5):

1.

8. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: In step (2), the dissolution temperature is 60~110℃, the dissolution time is 3~6h, and the mechanical stirring speed is 80~150r / min.

9. The method for preparing regenerated cellulose fibers / films by separating waste polyester / cotton using phosphate ester ionic liquids according to claim 1, characterized in that: In step (2), the polyester-cotton dissolution rate is 90.0-99.9%, and the degradation rate of regenerated cellulose is 2-10%.

10. The regenerated cellulose fiber / film prepared according to any one of claims 1-9, characterized in that: The regenerated cellulose fiber has a breaking strength of 1.0~2.3 cN / dtex and an elongation of 5%~17%. The regenerated cellulose film has a longitudinal tensile strength of 20~27 N / mm and a transverse tensile strength of 10~17 N / mm.

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