Method for separating and recycling cellulose-containing waste textiles

Abstract

The invention discloses a method for separating and recycling cellulose-containing waste textiles, and belongs to the technical field of cellulose textiles. Comprising the following steps: opening the cellulose-containing waste textile, and mixing with a cellulose solvent to obtain a mixture of a cellulose solution and an undissolved textile; and carrying out solid-liquid separation, recovering the cellulose solution, and washing and drying the undissolved fabric to obtain the non-cellulose component fabric. According to the method for separating, recycling and reusing the cellulose waste textiles, the alkali concentration is controlled to be 4-10%, the temperature is controlled to be 0-20 DEG C, degradation and damage of the non-cellulose component textiles are avoided to the maximum extent, and recycling of the non-cellulose component textiles is guaranteed. Meanwhile, the cellulose solution obtained by the method can realize simple and low-cost reutilization and product remanufacturing, and regenerated cellulose fibers, cellulose films and cellulose plastics can be obtained in modes of wet spinning, wet film forming, casting molding and the like.

Description

Technical Field

[0001] The invention relates to the technical field of cellulose textiles, and in particular to a method for separating and recycling waste cellulose-containing textiles. Background Art

[0003] The research on separation technology of waste cellulose-containing textiles has always been a hot topic for researchers. Currently, there are mainly physical, chemical and biological methods. These methods can achieve the separation of blended textiles to a certain extent, but there are still problems such as low separation efficiency, high cost and environmental pollution. Recently, green strategies such as ionic liquids and co-solvents have attracted attention for dissolving and separating waste cellulose-containing textiles. However, the ionic liquid and co-solvent systems have high costs, high equipment requirements and the system requires high purity of raw materials. How to achieve green and efficient separation of cotton-containing waste textiles is still a challenge. Therefore, starting from the essence of polymer physics, explore a low-cost and green strategy to improve the separation efficiency of waste fiber-containing textiles, and at the same time, green reprocess cellulose to achieve key technological breakthroughs and industrial development for the high-value utilization of waste textiles. Summary of the invention

[0004] The purpose of the present invention is to provide a method for separating and recycling waste textiles containing cellulose to solve the problems existing in the above-mentioned prior art. The solvent provided by the present invention is a sodium hydroxide aqueous solution (or a sodium hydroxide / urea aqueous solution), the system has wide applicability, and the recovered cellulose solution can be better reused.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is a method for separating and recycling waste cellulose-containing textiles, comprising the following steps:

[0007] After the cellulose-containing waste textile is opened, the mixture is mixed with a cellulose solvent to obtain a mixture of a cellulose solution and undissolved textile;

[0008] The solid and liquid are separated, the cellulose solution is recovered, and the undissolved fabric is washed and dried to obtain the non-cellulose component fabric.

[0009] Based on the above technical solution, the present invention has the following technical effects:

[0010] The present invention provides a method for separating, recycling and reusing waste cellulose-containing textiles, comprising a green solvent: 4 to 10 parts of alkali, 0 to 8 parts of urea, and 82 to 96 parts of water. In the method for separating, recycling and reusing waste cellulose textiles of the present invention, the alkali concentration is controlled at 4 to 10% and the temperature is controlled at 0 to -20°C, thereby avoiding the degradation and destruction of non-cellulose component fabrics to the greatest extent and ensuring the recycling of non-cellulose component fabrics. At the same time, the cellulose solution obtained by the present method can realize simple and low-cost reuse and product remanufacturing, including obtaining regenerated cellulose fibers, cellulose films and cellulose plastics by wet spinning, wet film forming and casting. The preparation method provided by the present invention is simple to operate and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] Figure 1 Schematic diagram of separation, recovery and reuse technology of waste textiles containing cellulose;

[0013] Figure 2 This is a microscopic picture of the waste textile in Example 2 after being dissolved in a low-temperature alkaline solution and filtered and separated;

[0014] Figure 3 Graph showing the tensile mechanical properties of the regenerated cellulose fibers and films obtained in step (6) of Examples 1 to 2 and Example 4. DETAILED DESCRIPTION

[0015] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0016] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0017] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0018] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0019] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0020] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or are publicly available.

[0021] The embodiment of the present invention provides a method for separating and recycling waste textiles containing cellulose, comprising the following steps:

[0022] After the cellulose-containing waste textile is opened, the mixture is mixed with a cellulose solvent to obtain a mixture of a cellulose solution and undissolved textile;

[0023] The solid and liquid are separated, the cellulose solution is recovered, and the undissolved fabric is washed and dried to obtain the non-cellulose component fabric.

[0024] In the present invention, unless otherwise specified, the cellulose-containing waste textile raw materials used in the present invention are preferably recycled waste textiles (including used old fabrics, textile manufacturing scraps, etc.).

[0025] The solid-liquid separation technique is preferably filter pressing.

[0026] In some specific embodiments, the cellulose-containing waste textiles include viscose, viscose / polyester and cotton / polyester.

[0027] In some specific embodiments, the cellulose solvent comprises the following raw materials in parts by weight: 4-10 parts of alkali, 0-8 parts of urea and 82-96 parts of water; preferably 6-10 parts of alkali, 2-5 parts of urea and 85-92 parts of water.

[0028] In some specific embodiments, the temperature of obtaining the cellulose solution is 0 to -20°C.

[0029] In some specific embodiments, the mass concentration of the cellulose solution is 1-10%.

[0030] In some specific embodiments, the recycling and reuse methods include wet spinning, wet film forming and casting.

[0031] In some specific embodiments, the cellulose solution is recycled to obtain regenerated cellulose filaments, cellulose films and cellulose plastic products.

[0032] In some specific embodiments, the mass concentration of cellulose in the mixture of cellulose solution and undissolved fabric is 4.67-5.94%, the mass concentration of lignin is 0.048-0.48%, and the mass concentration of inorganic material is 0.47-1.95%.

[0033] The regenerated cellulose fiber preparation process also includes pre-treatment (re-filtration and degassing treatment). In the present invention, the filtration is preferably continuous filtration; the pore size of the filter element of the filtration is preferably 1-20 μm; the degassing is preferably vacuum degassing or static degassing; the vacuum degassing time is preferably 3-6 hours, and the static degassing time is preferably 8-16 hours.

[0034] In the present invention, the regenerated cellulose fiber is preferably prepared by continuous wet spinning technology. In the present invention, the continuous wet spinning preferably includes: extruding the pre-treated cellulose solution through a wet spinning machine to regenerate filaments in a coagulation bath, stretching the preformed filaments through a drafting roller, washing with water to remove sodium hydroxide and coagulation bath components, and drying after oiling to obtain cellulose fibers.

[0035] In the present invention, the regenerated cellulose film is preferably prepared by a continuous wet film-forming process. In the present invention, the continuous wet film-forming process preferably comprises: extruding the cellulose solution through a slit extrusion device and continuously wet-forming the film in a coagulation bath, pulling and stretching, washing with water to remove sodium hydroxide and coagulation bath components, and drying to obtain a cellulose film.

[0036] In the present invention, the coagulation bath is preferably an organic solvent, an acid or a salt; the organic solvent is preferably an ethanol aqueous solution with a volume concentration of 60%; the acid is preferably sodium bicarbonate with a mass concentration of 10%, and the salt is preferably sodium citrate with a mass concentration of 10%.

[0037] In the present invention, the regenerated cellulose plastic is preferably prepared by casting technology. In the present invention, the casting technology preferably includes: pre-crosslinking of cellulose solution, casting, molding, washing, hydrophobic treatment, and drying molding.

[0038] In the present invention, the cellulose solution pre-crosslinking is preferably epichlorohydrin crosslinking;

[0039] In the present invention, the hydrophobic treatment is preferably a hexadecyltrimethoxysilane hydrophobic agent;

[0040] The present invention preferably further comprises cleaning, and the cleaning agent is preferably water. The present invention does not specifically limit the amount of the cleaning agent and the number of cleaning times, as long as the alkali and salt can be cleaned.

[0041] The present invention does not specifically limit the drying parameters, as long as the excess solvent can be completely removed.

[0042] Example 1

[0043] (1) Sodium hydroxide and water are mixed in a mass ratio of 8:92 and precooled at -12°C to obtain a cellulose solvent.

[0044] (2) Waste viscose / polyester (75% / 25%) was opened in a pulverizer to obtain a flocculent raw material, 12 g of the flocculent viscose / polyester was added to 100 g of a cellulose solvent, and mechanically stirred at -10°C to obtain a cellulose solution and a polyester fiber mixture.

[0045] In the present invention, the dissolution process is carried out under stirring conditions. The present invention does not specifically limit the stirring speed, as long as the cellulose can be fully dissolved.

[0046] (3) The mixed solution is filtered through a filter (20 μm) and pressurized to improve the separation efficiency to obtain a cellulose solution and polyester fibers.

[0047] (4) The residual polyester fiber solution is washed with water and then dried in an oven at 60° C. to obtain polyester fiber.

[0048] (5) The cellulose solution is further filtered step by step through a 20 μm-5 μm-1 μm filter element, and the filtrate is allowed to stand and degas for 3 hours.

[0049] (6) The degassed solution is extruded through a wet spinning machine into a 10 wt% sodium bicarbonate coagulation bath to regenerate filaments, and then washed, oiled, and dried to obtain regenerated cellulose fibers.

[0050] The cellulose mixed solution obtained in steps (2) and (5) and the separated cellulose solution were observed using an optical microscope. Figure 2 , polyester fiber maintains a good fiber morphology in low-temperature alkaline solution without obvious damage, and a clear and transparent cellulose solution can be obtained after filtration.

[0051] The tensile mechanical properties of the regenerated cellulose fiber obtained in step (6) were tested by a tensile performance test method. The result showed that the tensile strength of the regenerated cellulose fiber was 171.6 MPa.

[0052] Example 2

[0053] (1) Sodium hydroxide and water are mixed in a mass ratio of 8:92 and precooled at -12°C to obtain a cellulose solvent.

[0054] (2) Waste viscose / polyester (75% / 25%) was opened in a pulverizer to obtain a flocculent raw material, 12 g of the flocculent viscose / polyester was added to 100 g of a cellulose solvent, and mechanically stirred at -20°C to obtain a cellulose solution and a polyester fiber mixture.

[0055] (3) The mixed solution is filtered through a filter (20 μm) and pressurized to improve the separation efficiency to obtain a cellulose solution and polyester fibers.

[0056] (4) The residual polyester fiber solution is washed with water and then dried in an oven at 60° C. to obtain polyester fiber.

[0057] (5) The cellulose solution is further filtered step by step through a 20 μm-5 μm-1 μm filter element, and the filtrate is degassed for 3 hours.

[0058] (6) The degassed solution is formed into a film by a casting method, and then regenerated into a film in a 10 wt % sodium bicarbonate coagulation bath, and finally washed with water and dried to obtain a regenerated cellulose film.

[0059] The tensile mechanical properties of the regenerated cellulose film obtained in step (6) were tested by a tensile properties test method. The result showed that the tensile strength of the regenerated cellulose film was 102.9 MPa.

[0060] Example 3

[0061] (1) Sodium hydroxide and water are mixed in a mass ratio of 8:92 and precooled at -12°C to obtain a cellulose solvent.

[0062] (2) Waste viscose / polyester (75% / 25%) was opened in a pulverizer to obtain a flocculent raw material, 12 g of the flocculent viscose / polyester was added to 100 g of a cellulose solvent, and mechanically stirred at 0° C. to obtain a cellulose solution and a polyester fiber mixture.

[0063] (3) The mixed solution is filtered through a filter (20 μm) and pressurized to improve the separation efficiency to obtain a cellulose solution and polyester fibers.

[0064] (4) The residual polyester fiber solution is washed with water and then dried in an oven at 60° C. to obtain polyester fiber.

[0065] (5) 1.5 mL of epichlorohydrin is further added to the cellulose solution, cross-linked at 5°C, centrifuged for degassing, injected into a specific mold, and molded at room temperature for 12 hours. The cellulose plastic box is obtained after washing and drying.

[0066] Example 4

[0067] (1) Sodium hydroxide, urea and water are mixed in a mass ratio of 8:4:88 and precooled at -12°C to obtain a cellulose solvent.

[0068] (2) Waste cotton / polyester (50% / 50%) was opened in a pulverizer to obtain a flocculent raw material, 6 g of the flocculent cotton / polyester was added to 100 g of a cellulose solvent, and mechanically stirred at -10°C to obtain a cellulose solution and a polyester fiber mixture.

[0069] (3) The mixed solution is filtered through a filter (20 μm) and pressurized to improve the separation efficiency to obtain a cellulose solution and polyester fibers.

[0070] (4) The residual polyester fiber solution is washed with water and then dried in an oven at 60° C. to obtain polyester fiber.

[0071] (5) The cellulose solution is further filtered step by step through a 20 μm-5 μm-1 μm filter element, and the filtrate is allowed to stand and degas for 3 hours.

[0072] (6) The degassed solution is formed into a film by a casting method, and then the film is regenerated in a 60% ethanol solid bath, and finally washed with water and dried to obtain a regenerated cellulose film.

[0073] The tensile mechanical properties of the regenerated cellulose film obtained in step (6) were tested by a tensile properties test method. The result showed that the tensile strength of the regenerated cellulose film was 142.6 MPa.

[0074] Comparative Example 1

[0075] (1) Sodium hydroxide and water are mixed in a mass ratio of 8:92 and precooled at -12°C to obtain a cellulose solvent.

[0076] (2) The waste polyester was opened in a pulverizer to obtain a flocculent raw material, 12 g of the polyester was added to 100 g of a cellulose solvent, and mechanically stirred at -10°C to obtain a polyester fiber mixed solution.

[0077] (3) The mixed solution is filtered through a filter (20 μm) and pressurized to improve the separation efficiency to obtain a cellulose solution and polyester fibers.

[0078] (4) The residual polyester fiber solution is washed with water and then dried in an oven at 60° C. to obtain polyester fiber.

[0079] (5) Conducting quality inspection on the polyester fiber obtained in (4).

[0080] Through quality testing, it was found that there was almost no loss of polyester during the solvent treatment process, and the recovery rate was 95-100%. By comparison with Example 1, it was found that the low-temperature alkaline solvent selectively dissolved cellulose, retained cellulose, and achieved efficient separation of viscose / polyester.

[0081] Comparative Example 2

[0082] (1) Sodium hydroxide, urea and water are mixed in a mass ratio of 8:4:88 and precooled at -12°C to obtain a cellulose solvent.

[0083] (2) Waste cotton / polyester (75% / 25%) was opened in a pulverizer to obtain a flocculent raw material, 12 g of the flocculent cotton / polyester was added to 100 g of a cellulose solvent, and mechanically stirred at -10°C to obtain a cellulose solution and a polyester fiber mixture.

[0084] (3) The mixed solution is filtered through a filter (20 μm) and pressurized to improve the separation efficiency to obtain a cellulose solution and polyester fibers.

[0085] (4) The residual polyester fiber solution was fully washed with water and then dried in an oven at 60° C. to obtain a fiber product.

[0086] (5) The cellulose solution is further filtered step by step through a 20 μm-5 μm-1 μm filter element, and the filtrate is allowed to stand and degas for 3 hours.

[0087] (6) The degassed solution is formed into a film by a casting method, and then the film is regenerated in a 60% ethanol solid bath, and finally washed with water and dried to obtain a regenerated cellulose film.

[0088] Through the test of Comparative Example 2, it was found that (4) the obtained product contained cellulose and polyester, and (6) the moldability was poor, indicating that the cellulose concentration was low. That is, compared with Examples 1 and 3, the separation effect of this method on cotton / polyester was relatively poor, because the cellulose molecular weight of cotton was high and its solubility was relatively low compared with viscose.

[0089] In summary, the present invention provides a method for separating and recycling cellulose-containing textiles. A green alkali system for separating cellulose-containing textiles is provided, and the cellulose component in the textiles is physically dissolved by a green solvent (sodium hydroxide aqueous solution or sodium hydroxide / urea aqueous solution), thereby achieving efficient separation of cellulose-containing textiles (viscose fiber / polyester, cotton / polyester and other textiles). The method avoids the degradation of the second component (such as polyester) to the greatest extent, and obtains a cellulose solution at the same time. Finally, the separated cellulose solution is used for the development of cellulose regeneration products, such as regenerated fibers, regenerated films and bioplastics.

[0090] Obviously, the above embodiments of the present invention are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For ordinary technical users in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for separating and recycling waste cellulose-containing textiles, characterized in that: The following steps are involved: After the cellulose-containing waste textile is opened, the mixture is mixed with a cellulose solvent to obtain a mixture of a cellulose solution and undissolved textile; The solid and liquid are separated, the cellulose solution is recovered, and the undissolved fabric is washed and dried to obtain the non-cellulose component fabric.

2. The method according to claim 1, characterized in that: The cellulose-containing waste textiles include viscose, viscose / polyester and cotton / polyester.

3. The method according to claim 1, characterized in that The cellulose solvent comprises the following raw materials in parts by weight: 4 to 10 parts of alkali, 0 to 8 parts of urea and 82 to 96 parts of water.

4. The method according to claim 1, characterized in that: The temperature of the cellulose solution is 0 to -20°C.

5. The method according to claim 1, characterized in that The mass concentration of the cellulose solution is 1-10%.

6. The method according to claim 1, characterized in that The recycling and reuse methods include wet spinning, wet film forming and casting.

7. The method according to claim 6, characterized in that The cellulose solution is recycled to obtain regenerated cellulose silk, cellulose film and cellulose plastic products.

8. The method according to claim 1, characterized in that: The mass concentration of cellulose in the mixture of cellulose solution and undissolved fabric is 4.67-5.94%, the mass concentration of lignin is 0.048-0.48%, and the mass concentration of inorganic material is 0.47-1.95%.

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