Method for recycling fiber products containing cellulose as main component

Abstract

Provided is a method for recycling fiber products containing cellulose, whereby even cellulose materials that are difficult to recycle, such as materials deteriorated by repeated use, materials having a reduced degree of cellulose polymerization due to decrosslinking agent treatment, defunctionalization agent treatment, decolorization treatment, or repeated recycling of fiber products, and materials having a low degree of polymerization of original cellulose such as Rayon or Lyocell, can be regenerated into cellulosic fibers having sufficient strength.　A method for recycling fiber products containing cellulose as a main component comprises at least: a decomposition step for decomposing cellulose into sugar; and a bacterial cellulose generation step for generating fiber product-derived bacterial cellulose by using the sugar obtained by the decomposition step as a material.

Description

Method for recycling textile products whose main component is cellulose

[0001] The present invention relates to a method for recycling textile products whose main component is cellulose.

[0002] The fashion industry has come to be seen as an industry with a significant environmental impact due to mass production, mass consumption, and mass waste, which has led to increased resource and energy consumption in manufacturing and a shorter life cycle, and this has become an international issue.

[0003] In order to realize a recycling-oriented society, various measures are being taken to make effective use of resources and reduce waste, but many textile products such as clothing are discarded or incinerated after use.

[0004] Regarding cellulose materials, reasons for disposal or incineration include deterioration due to repeated use of textile products, a decrease in the degree of polymerization of cellulose due to repeated pre-treatment and recycling, and the fact that materials such as rayon and lyocell, which have a low degree of polymerization of the original cellulose, are not suitable for use as recycled materials.

[0005] Patent Document 1 (JP 2024-504096 A) discloses high tenacity regenerated cellulosic fibers prepared from a cellulosic raw material, the cellulosic raw material comprising 5 to 100% by weight of pretreated bacterial cellulose having a degree of polymerization in the range of 450 to 2000; and 0 to 95% by weight of an additional cellulosic material selected from the group consisting of dissolving grade pulp, bamboo pulp, hemp, recycled cotton pulp, regenerated cellulosic materials, and mixtures thereof, the fibers having a tenacity of at least 4.5 grams / denier and an elongation of at least 10% as measured in accordance with ASTM D 3822.

[0006] Patent document 2 (CN Patent No. 101492837) describes a method for preparing regenerated bacterial cellulose fibers by using bacterial cellulose with a high degree of polymerization of 1500 to 16000, dissolving it in a suitable solvent such as an ionic liquid to prepare a solution in the range of 1 to 30%, and then filtering and spinning it.

[0007] However, Patent Documents 1 and 2 do not consider the recycling of textile products containing cellulose, in particular the recycling of cellulose materials that are difficult to recycle, such as materials that have deteriorated due to repeated use, materials whose degree of cellulose polymerization has decreased due to repeated pretreatment and recycling, or materials such as rayon and lyocell, whose cellulose itself originally has a low degree of polymerization.

[0008] Special Publication No. 2024-504096 Chinese Patent No. 101492837 Specification

[0009] The present invention relates to a method for recycling textile products containing cellulose, and aims to provide a recycling method capable of regenerating into cellulosic fibers having sufficient strength even cellulose materials that are difficult to recycle, such as materials that have deteriorated due to repeated use, materials whose cellulose polymerization degree has decreased due to textile product treatment with a decrosslinking agent, treatment with a defunctionalizing agent, or bleaching treatment, or repeated recycling, and materials whose original cellulose polymerization degree is low, such as rayon and lyocell.

[0010] As a result of extensive research, the present inventors have discovered that in a method for recycling textile products whose main component is cellulose, it is possible to regenerate the cellulose into cellulosic fibers with sufficient strength by providing at least a decomposition step for decomposing the cellulose into sugars and a bacterial cellulose production step for producing bacterial cellulose derived from the textile product using the sugar obtained in the decomposition step, and have completed the present invention.

[0011] The present invention is a method for recycling textile products whose main component is cellulose, and is based on the following technology.

[0012] (1) A method for recycling textile products whose main component is cellulose, comprising at least a decomposition step of decomposing cellulose into sugars, and a bacterial cellulose production step of producing textile-derived bacterial cellulose using the sugars obtained in the decomposition step.

[0013] (2) The method for recycling textile products according to (1), wherein the textile product mainly composed of cellulose contains one or more types of cellulosic fibers selected from cotton, rayon, and lyocell.

[0014] (3) The method for recycling textile products according to (2), wherein part or all of the cellulosic fibers are cellulosic fibers that have been recycled multiple times.

[0015] (4) The method for recycling textile products according to any one of (1) to (3), wherein the bacterial cellulose production step is a step of producing bacterial cellulose using acetic acid bacteria.

[0016] (5) A method for recycling textile products according to any one of (1) to (4), comprising a bacterial cellulose dissolving step of dissolving the bacterial cellulose obtained in the bacterial cellulose production step in a solvent.

[0017] (6) The method for recycling textile products according to (5), comprising a bacterial cellulose solution / cellulose component solution mixing step of mixing the bacterial cellulose solution obtained in the bacterial cellulose dissolution step with a cellulose component solution in which cellulose components other than bacterial cellulose are dissolved in a solvent.

[0018] (7) The method for recycling textile products according to (5) or (6), wherein the solvent is an ionic liquid.

[0019] (8) A method for recycling a textile product according to any one of (1) to (4), comprising a bacterial cellulose / cellulose component mixing step of mixing the bacterial cellulose obtained in the bacterial cellulose production step with a cellulose component other than bacterial cellulose.

[0020] (9) The method for recycling textile products according to (8), comprising a step of dissolving a mixture of bacterial cellulose and cellulose components, in which the mixture of bacterial cellulose obtained in the step of mixing bacterial cellulose and cellulose components and cellulose components other than bacterial cellulose is dissolved in a solvent.

[0021] (10) The method for recycling textile products according to (9), wherein the solvent is an ionic liquid.

[0022] According to the present invention, a recycling method for textile products containing cellulose can be provided that can regenerate into cellulosic fibers with sufficient strength even cellulosic materials that are difficult to recycle, such as materials that have deteriorated due to repeated use, materials that have had their degree of cellulose polymerization reduced due to textile products being treated with a decrosslinking agent, a defunctionalizing agent, or a bleaching treatment, or repeated recycling, and materials such as rayon and lyocell, whose cellulose itself originally has a low degree of polymerization.

[0023] In the present invention, the method for recycling textile products containing cellulose as a main component includes at least a decomposition step of decomposing cellulose into sugars and a bacterial cellulose production step of producing textile-derived bacterial cellulose using the sugars obtained in the decomposition step.

[0024] <Textile products containing cellulose as a main component> In the present invention, the textile product containing cellulose as a main component refers to a textile product containing one or more cellulosic fibers selected from cotton, rayon, and lyocell, and may be a textile product made of 100% cellulosic fibers, or a textile product made of a composite fiber of cellulosic fibers and fibers other than cellulosic fibers. Also, the cellulose fibers may be cellulosic fibers that have been partially or entirely recycled multiple times.

[0025] When the textile product is made of a composite fiber of cellulosic fibers and fibers other than cellulosic fibers, a cellulosic fiber separation step can be provided in which only the cellulosic fibers are extracted.

[0026] Furthermore, if the textile product has been treated with a crosslinking agent, a decrosslinking agent treatment may be carried out; if the textile product has been treated with a functional finishing agent such as stain-resistant, deodorizing, water-repellent, or cool feeling, a defunctionalizing agent treatment may be carried out; and if the textile product has been dyed, a decolorizing treatment may be carried out.

[0027] By providing the cross-linking removal agent treatment step, the functionalization removal agent treatment step, and the decolorization treatment step, impurities are removed, and the conversion rate of cellulose to sugars can be increased in the decomposition step described next.

[0028] The cross-linking agent removing treatment step, functionalizing agent removing treatment step, and decolorizing treatment step may be carried out either before or after the cellulosic fiber separation step.

[0029] <Decomposition Step> In the decomposition step, cellulose is decomposed into sugars. Cellulose is a polysaccharide in which 1,000 or more glucose molecules are linked by β-glycosidic bonds, and by decomposing cellulose, glucose, a monosaccharide, can be obtained.

[0030] Methods for decomposing cellulose into sugars include thermal decomposition, acid catalyst methods using sulfuric acid or the like as a catalyst (e.g., alkenol method), pressurized hot water methods in which cellulose is hydrolyzed in a supercritical or subcritical aqueous solution, and enzyme reaction methods in which cellulose is hydrolyzed by an enzymatic reaction.

[0031] Enzymatic reaction methods using cellulase-containing enzymes are preferred because they consume less energy than chemical methods that use chemicals or high temperatures and pressures, can be carried out under mild reaction conditions, and produce fewer by-products.

[0032] <Bacterial cellulose production step> In the bacterial cellulose production step, bacterial cellulose is produced by culturing cellulose-producing bacteria in a medium containing the sugar (glucose) obtained in the decomposition step, and the liquid component is removed from the obtained bacterial cellulose.

[0033] The culture method may be a known method such as a static culture method or an agitation culture method, and from the viewpoint of the rapid rate of bacterial cellulose production, it is preferable to apply the agitation culture method.

[0034] Cellulose-producing bacteria are bacteria that produce bacterial cellulose, and examples thereof include bacteria of the genus Komagataibacter, Acetobacter, Gluconacetobacter, Pseudomonas, Agrobacterium, Rhizobium, and Enterobacter.

[0035] As the cellulose-producing bacteria, it is preferable to use acetic acid bacteria belonging to the genus Acetobacter, from the viewpoint of high cellulose production ability and ease of cultivation.

[0036] Furthermore, the components contained in the medium other than glucose are not particularly limited, but are determined taking into consideration the type of bacteria used, culture conditions, production costs, and the like.

[0037] Examples of components of the medium include a nitrogen source, inorganic salts, and organic trace nutrients.

[0038] Examples of the nitrogen source include organic or inorganic nitrogen sources such as ammonium salts such as ammonium sulfate, ammonium chloride, and ammonium phosphate, nitrates, urea, and peptone.

[0039] Examples of inorganic salts include phosphate salts, magnesium salts, calcium salts, iron salts, and manganese salts.

[0040] Examples of organic micronutrients include amino acids, vitamins, fatty acids, nucleic acids, and further, peptones containing these nutrients, yeast extract, casamino acids, and soy protein hydrolysates. When an auxotrophic mutant strain that requires amino acids for growth is used, the required nutrients can be further supplemented to the medium.

[0041] <Bacterial cellulose dissolving step> This is a step of dissolving the bacterial cellulose obtained in the bacterial cellulose production step in a solvent.

[0042] Examples of the solvent include N-methylmorpholine-N-oxide (NMMO), dimethyl sulfoxide / calcium chloride, dimethylacetamide / lithium chloride, and ionic liquids. Ionic liquids are preferred because they can dissolve cellulose under mild conditions and have high cellulose solubility.

[0043] The bacterial cellulose solution obtained in the bacterial cellulose dissolution step is subjected to dry-wet spinning in the fiber formation step, whereby cellulosic fibers with sufficient strength can be obtained.

[0044] <Step of Mixing Bacterial Cellulose Lysate and Cellulose Component Lysate> Cellulose components other than bacterial cellulose may be added to the bacterial cellulose lysate obtained in the bacterial cellulose dissolving step.

[0045] In this case, a bacterial cellulose lysate / cellulose component lysate mixing step is provided in which a cellulose component lysate in which cellulose components other than bacterial cellulose are dissolved in a solvent is added to and mixed with the bacterial cellulose lysate obtained in the bacterial cellulose dissolving step.

[0046] In the step of mixing the bacterial cellulose solution and the cellulose component solution, the solvent for dissolving the cellulose components other than bacterial cellulose is the same as the solvent used in the bacterial cellulose dissolving step.

[0047] The mixed solution of bacterial cellulose solution and cellulose component solution obtained in the bacterial cellulose solution / cellulose component solution mixing step is subjected to dry / wet spinning in the fiber forming step, whereby cellulose-based fibers with sufficient strength can be obtained.

[0048] In the above-mentioned bacterial cellulose solution / cellulose component solution mixing step, the bacterial cellulose solution is mixed with a cellulose component solution in which cellulose components other than bacterial cellulose are dissolved in a solvent, but the bacterial cellulose and the bacterial cellulose components can also be mixed before being dissolved in a solvent.

[0049] <Bacterial cellulose and cellulose component mixing step> This is a step of mixing the bacterial cellulose obtained in the bacterial cellulose production step with cellulose components other than bacterial cellulose.

[0050] <Step of Dissolving Bacterial Cellulose and Cellulose Component Mixture> This is a step of dissolving the bacterial cellulose and cellulose component mixture obtained in the bacterial cellulose and cellulose component mixing step in a solvent.

[0051] Examples of the solvent include N-methylmorpholine-N-oxide (NMMO), dimethyl sulfoxide / calcium chloride, dimethylacetamide / lithium chloride, and ionic liquids. Ionic liquids are preferred because they can dissolve cellulose under mild conditions and have high cellulose solubility.

[0052] The bacterial cellulose / cellulose component mixture solution obtained in the bacterial cellulose / cellulose component mixture dissolution step is subjected to dry / wet spinning in the fiber formation step, whereby cellulosic fibers with sufficient strength can be obtained.

[0053] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0054] (Example 1) <Decomposition step> Cellulosic fibers were separated from textile waste and then finely pulverized using a pulverizer. 0.1 M acetate buffer (pH 5.0), 5 w / v % of the pulverized cellulosic fibers, and 1 w / v % of cellulase were placed in an Erlenmeyer flask, and the mixture was saccharified at 50°C for 96 hours using a thermostatic shaker to obtain glucose.

[0055] <Bacterial cellulose production step> The glucose obtained in the above decomposition step was replaced with glucose in Hestrin-Schram standard medium (glucose: 2%, bactopeptone: 0.5%, yeast extract: 0.5%, disodium hydrogen phosphate: 0.27%, citric acid: 0.12%, adjusted to pH 6.8), and acetic acid bacteria (Gluconacetobacter xylinus) were added to this medium and allowed to stand at 30°C for 7 days. After standing, the produced pellicles were collected and immersed in 1N NaOH overnight. After immersion, the pellicles were washed with distilled water until neutral, and bacterial cellulose was obtained.

[0056] <Bacterial cellulose dissolution step> The bacterial cellulose obtained in the bacterial cellulose production step was freeze-dried and then pulverized in a ball mill to obtain bacterial cellulose powder. A twin-screw kneader (KZW15TW-120MG-NH(-1100), L / D 120, screw diameter 15 mm, manufactured by Technovel Co., Ltd.) was preheated to 95°C, the screw rotation speed was set to 100 rpm, and the ionic liquid DBUH·AcO was supplied at 321 g / h. After increasing the screw rotation speed to 500 rpm, bacterial cellulose powder was supplied at a supply rate of 10 g / h. Kneading was performed under conditions of a residence time (mixing time) of approximately 23 minutes, and a bacterial cellulose solution was obtained.

[0057] <Fibration step> The bacterial cellulose solution obtained in the bacterial cellulose dissolution step was supplied to a spinneret (manufactured by a synthetic fiber nozzle, number of holes: 100, hole diameter: 0.4 mm), and spun under the conditions of a dry-wet spinning method (spinning speed: 10 m / min, coagulation bath temperature (water temperature): 5°C) to obtain a long fiber with a fineness of 1.7 dtex.

[0058] <Evaluation of Fiber> The properties of the continuous fiber of Example 1 obtained in the above fiberization process were measured using a tensile tester (Autograph AGS-X, 10N-10kN, manufactured by Shimadzu Corporation). The strength was 5.7 cN / dtex, which was sufficient strength.

[0059] (Example 2) <Bacterial cellulose / cellulose component mixing step> 50 parts of freeze-dried bacterial cellulose obtained through the same decomposition step and bacterial cellulose production step as in Example 1 and 50 parts of 100% cotton textile waste were charged into a ball mill grinder, and grinding and mixing were carried out simultaneously in the grinder to obtain a bacterial cellulose / cellulose component mixture with a bacterial cellulose component:other cellulose component ratio of 50:50.

[0060] <Bacterial cellulose / cellulose component mixture dissolving step> The bacterial cellulose / cellulose component mixture obtained in the bacterial cellulose / cellulose component mixing step was used as a raw material and fed into a twin-screw kneader under the same conditions as in Example 1 to obtain a bacterial cellulose / cellulose component mixture solution.

[0061] <Fiber Formation Step> The bacterial cellulose / cellulose component mixture solution obtained in the bacterial cellulose / cellulose component mixture dissolving step was supplied to the fiber formation step, and subjected to dry / wet spinning under the same conditions as in Example 1 to obtain long fibers with a fineness of 1.7 dtex.

[0062] <Evaluation of Fiber> The properties of the long fibers of Example 2 obtained in the above fiberization process were measured using a tensile tester (Shimadzu Autograph AGS-X, 10N-10kN). The strength was 5.3 cN / dtex, which was sufficient strength.

[0063] Comparative Example 1: 100% rayon fiber waste was fed into a ball mill to obtain rayon powder. Using this powder as a raw material without going through the bacterial cellulose production process, the dissolution process and fiberization process were attempted in the same manner as in Example 1. However, the viscosity of the solution was extremely low and the spinnability was poor, so spinning was not possible and a fibrous sample could not be obtained.

[0064] Comparative Example 2 50 parts of 100% rayon fiber waste and 50 parts of 100% cotton fiber cutting waste were charged into a ball mill grinder, and grinding and mixing were simultaneously carried out in the grinder to obtain a mixed powder of rayon component:other cellulose component=50:50.

[0065] Using this powder as a raw material, the dissolution process and fiber formation process were attempted in the same manner as in Example 1. Spinning was possible under the same conditions as in Example 1, and a long fiber sample could be obtained, but frequent fiber breakage occurred and the spinning state was unstable.

[0066] The physical properties of the obtained continuous fiber of Comparative Example 2 were measured using a tensile tester (Autograph AGS-X, 10N-10kN, manufactured by Shimadzu Corporation), and the strength was 2.4 cN / dtex, which was insufficient.

[0067] According to the present invention, it is possible to provide a recycling method capable of regenerating into cellulosic fibers with sufficient strength cellulosic materials that are difficult to recycle, such as materials that have deteriorated due to repeated use, materials that have been treated with a decrosslinking agent, a defunctionalizing agent, or a bleaching treatment on textile products, or materials whose degree of cellulose polymerization has decreased due to repeated recycling, and materials such as rayon and lyocell, whose original degree of polymerization of cellulose itself is low, and the present invention is of great practical value.

Claims

1. A method for recycling textile products whose main component is cellulose, comprising at least a decomposition step of decomposing cellulose into sugars, and a bacterial cellulose production step of producing textile-derived bacterial cellulose using the sugars obtained in the decomposition step.

2. The method for recycling textile products according to claim 1, characterized in that the textile products containing cellulose as a main component contain one or more types of cellulosic fibers selected from cotton, rayon and lyocell.

3. The method for recycling textile products according to claim 2, wherein part or all of the cellulosic fibers are cellulosic fibers that have been recycled multiple times.

4. The method for recycling textile products according to claim 1, wherein the bacterial cellulose production step is a step of producing bacterial cellulose using acetic acid bacteria.

5. The method for recycling textile products according to claim 1, further comprising a bacterial cellulose dissolving step of dissolving the bacterial cellulose obtained in the bacterial cellulose production step in a solvent.

6. The method for recycling textile products according to claim 5, characterized in that it includes a bacterial cellulose solution / cellulose component solution mixing step of mixing the bacterial cellulose solution obtained in the bacterial cellulose dissolution step with a cellulose component solution in which cellulose components other than bacterial cellulose are dissolved in a solvent.

7. The method for recycling textile products according to claim 5, wherein the solvent is an ionic liquid.

8. The method for recycling textile products according to claim 1, characterized in that it comprises a bacterial cellulose / cellulose component mixing step of mixing the bacterial cellulose obtained in the bacterial cellulose production step with cellulose components other than bacterial cellulose.

9. The method for recycling textile products according to claim 8, further comprising a step of dissolving a mixture of bacterial cellulose and cellulose components, in which the mixture of bacterial cellulose obtained in the step of mixing bacterial cellulose and cellulose components and cellulose components other than bacterial cellulose is dissolved in a solvent.

10. The method for recycling textile products according to claim 9, wherein the solvent is an ionic liquid.