Method for recycling cellulosic fiber products

Abstract

The present invention relates to a method for recycling a cellulose-containing fiber product, and an object of the present invention is to provide a recycling method capable of regenerating a cellulose-based fiber having sufficient strength even in a cellulose material which is difficult to be recycled, such as a material deteriorated due to repeated use, a material having a reduced cellulose polymerization degree due to a decrosslinking agent treatment, a defunctionalizing agent treatment, or a decoloring treatment of a fiber product, or a material having a low polymerization degree of original cellulose itself, such as rayon or lyocell.SOLUTION: The method for recycling a fiber product containing cellulose as a main component includes at least a decomposition step of decomposing cellulose into sugar and a bacterial cellulose production step of producing bacterial cellulose derived from the fiber product using the sugar obtained in the decomposition step as a material.SELECTED DRAWING: None

Description

[Technical Field]

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

[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, as well as increased resource and energy consumption in manufacturing and shorter life cycles, 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 and 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] Cited Document 1 (JP 2024-504096 A) discloses high tenacity regenerated cellulosic fibers prepared from cellulosic raw materials, the cellulosic raw materials including 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, reclaimed 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] Reference 2 (Chinese Patent No. 101492837) describes a method for preparing regenerated bacterial cellulose fibers by using bacterial cellulose with a high degree of polymerization of 1500-16000, dissolving it in a suitable solvent such as an ionic liquid to prepare a solution in the range of 1-30%, and then filtering and spinning it.

[0007] However, neither Cited Document 1 nor Cited Document 2 considers the recycling of textile products containing cellulose, particularly the recycling of difficult-to-recycle cellulose materials such as materials that have deteriorated due to repeated use, materials whose degree of cellulose polymerization has decreased due to repeated pretreatment or recycling, or materials such as rayon and lyocell whose cellulose itself has a low degree of polymerization. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2024-504096 [Patent Document 2] Chinese Patent No. 101492837 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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 bacterial cellulose derived from textile products using the sugars obtained in the decomposition step.

[0013] (2) A method for recycling textile products according to (1), wherein the textile product containing cellulose as a main component contains one or more types of cellulosic fibers selected from cotton, rayon, and lyocell.

[0014] (3) The method for recycling a textile product 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 waste according to any one of (1) to (4), which comprises 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 waste 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 waste 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 waste according to (8), which comprises a step of dissolving a mixture of bacterial cellulose and cellulose components, obtained in the step of mixing bacterial cellulose and cellulose components, in a solvent.

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

[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. DETAILED DESCRIPTION OF THE INVENTION

[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 whose main component is cellulose> In the present invention, a textile product containing cellulose as a main component refers to a textile product containing one or more types of cellulosic fibers selected from cotton, rayon, and lyocell, and may be a textile product made of 100% cellulosic fibers, a textile product made of a composite fiber of cellulosic fibers and fibers other than cellulosic fibers, or a cellulose fiber in which part or all of the cellulosic fibers have been 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] <Disassembly process> In the decomposition process, cellulose is broken down into sugars. Cellulose is a polysaccharide consisting of more than 1,000 glucose molecules linked together by β-glycosidic bonds, and by decomposing cellulose, the monosaccharide glucose 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., the 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 process> 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 selected 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 nitrogen sources 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 dissolution process> This is a step of dissolving the bacterial cellulose obtained in the bacterial cellulose production step in a solvent.

[0042] Examples of solvents 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 dissolving step is subjected to dry-wet spinning in the fiber forming step, whereby cellulosic fibers with sufficient strength can be obtained.

[0044] <Bacterial cellulose lysate and cellulose component lysate mixing process> Cellulose components other than bacterial cellulose may be added to the bacterial cellulose solution obtained in the bacterial cellulose dissolution 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 the bacterial cellulose lysate obtained in the bacterial cellulose dissolving step and mixed.

[0046] In the step of mixing the bacterial cellulose dissolving solution and the cellulose component dissolving 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, thereby obtaining cellulosic fibers with sufficient strength.

[0048] In the above-mentioned mixing process of the bacterial cellulose solution and the cellulose component solution, the bacterial cellulose solution is mixed with the 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 the solvent.

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

[0050] <Bacterial cellulose and cellulose component mixture dissolution process> This is a step of dissolving the bacterial cellulose / cellulose component mixture obtained in the bacterial cellulose / cellulose component mixing step in a solvent.

[0051] Examples of solvents 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, thereby obtaining cellulosic fibers with sufficient strength. [Example]

[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 <Disassembly process> After separating the cellulosic fibers from the textile waste, they were finely pulverized using a grinder. A 0.1 M acetate buffer solution (pH 5.0), 5 w / v% of the pulverized cellulosic fibers, and 1 w / v% 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 process> The glucose obtained in the decomposition process was replaced with glucose in Hestrin-Schramm 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 formed pellicles were collected and soaked in 1N NaOH overnight. After soaking, they were washed with distilled water until neutral, yielding bacterial cellulose.

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

[0057] <Fiber production process> The bacterial cellulose solution obtained in the bacterial cellulose dissolution step was supplied to a spinneret (a synthetic fiber nozzle with 100 holes and a hole diameter of 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] <Fiber evaluation> The physical properties of the long fibers of Example 1 obtained in the above fiberization process were measured using a tensile tester (Shimadzu Autograph AGS-X, 10N-10kN). The strength was 5.7 cN / dtex, which was sufficient strength.

[0059] Example 2 <Bacterial cellulose and cellulose component mixing process> Fifty parts of freeze-dried bacterial cellulose obtained through the same decomposition process and bacterial cellulose production process as in Example 1 and 50 parts of 100% cotton textile waste were placed in 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 and cellulose component mixture dissolution process> The bacterial cellulose and cellulose component mixture obtained in the bacterial cellulose and cellulose component mixing step was used as a raw material and was fed into a twin-screw kneader under the same conditions as in Example 1 to obtain a bacterial cellulose and cellulose component mixture solution.

[0061] <Fiber production process> The bacterial cellulose / cellulose component mixture solution obtained in the bacterial cellulose / cellulose component mixture dissolution process was supplied to the fiberization process, and dry / wet spinning was carried out under the same conditions as in Example 1 to obtain long fibers with a fineness of 1.7 dtex.

[0062] <Fiber evaluation> The physical 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), and the strength was 5.3 cN / dtex, which was sufficient strength.

[0063] (Comparative Example 1) Rayon powder was obtained by feeding 100% rayon fiber waste into a ball mill. Using this powder as a raw material without going through the bacterial cellulose production process, the dissolution and fiberization processes 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) Fifty parts of 100% rayon textile waste and 50 parts of 100% cotton textile cutting waste were put into a ball mill grinder, and by simultaneously grinding and mixing in the grinder, a mixed powder of rayon components and other cellulose components = 50:50 was obtained.

[0065] Using this powder as a raw material, the dissolution process and fiberization 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 was obtained, but the spinning conditions were unstable with frequent thread breakage.

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

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

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

4. 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. 5. The method for recycling textile waste 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. 6. The textile waste recycling method according to claim 5, further 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.

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

8. 5. The method for recycling textile products according to claim 1, further 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.

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

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