A kind of easily recyclable nylon-spandex fabric and recycling method thereof

Abstract

The present invention provides a nylon-spandex fabric that is easy to recycle and a recycling method thereof, wherein the fabric comprises nylon and spandex, wherein the dihydroxy compound raw material of the spandex comprises polyether ester diol, and the structure of the polyether ester diol comprises an ester bond and a polyether segment. The fabric adopts an alkali-alcohol solution to dissolve the spandex therein during the recycling process, and then the remaining nylon is physically or chemically recycled after the fabric is rinsed. In the nylon-spandex fabric of the present invention, the spandex contains a polyether ester segment, and the spandex can be decomposed during the fabric recycling process by an alkali-alcohol solution, while the nylon is retained, so as to avoid the spandex from becoming an impurity in the nylon recycling process. Compared with conventional polyester-type spandex, the decomposition speed of the spandex in the nylon-spandex fabric of the present invention is faster, thereby improving the recycling efficiency of the nylon-spandex fabric.

Description

Technical Field

[0001] The invention relates to the field of blended fabric recycling, and in particular to an easily recyclable nylon-spandex fabric and a recycling method thereof. Background Art

[0002] Nylon-spandex fabric refers to textiles mainly blended from nylon and spandex. Nylon is polyamide fiber, also known as nylon, which has the characteristics of good wear resistance, not easy to wrinkle, easy to wash, and quick drying. Spandex is polyurethane fiber, which is usually obtained by reacting dihydroxy compounds and diisocyanate compounds to form prepolymers, and then using chain extenders to extend the chain. Spandex has excellent stretching and resilience properties, which can increase the elasticity and comfort of the fabric. The nylon-spandex fabric blended from the two is widely used in T-shirts, shirts, tights, down jackets, jackets and other clothing due to its advantages of wear resistance and high elasticity.

[0003] At present, nylon is mainly recycled by chemical or physical methods. The physical method recycles by melt regeneration, while the chemical method chemically degrades nylon into nylon raw materials, and then prepares nylon for reuse. When nylon-spandex fabrics containing nylon and spandex are physically recycled, spandex, as an impurity, cannot normally participate in the melt regeneration of nylon; when chemically degraded, spandex will also degrade in the process, and its degradation products, as impurities, will affect the quality of nylon chemical degradation products caprolactam (for nylon 66, it is adipic acid and hexamethylenediamine).

[0004] In order to solve the above problems, the present invention provides an easily recyclable nylon-spandex fabric and a recycling method thereof. Summary of the invention

[0005] The object of the present invention is to provide a nylon-spandex fabric that is easy to recycle and a recycling method thereof, which can prevent nylon from becoming an impurity in the recycling process. The specific scheme is as follows:

[0006] The invention discloses a nylon-spandex fabric which is easy to recycle. The fabric comprises nylon and spandex, and is characterized in that the dihydroxy compound raw material of the spandex comprises polyether ester diol, and the structure of the polyether ester diol comprises an ester bond and a polyether segment.

[0007] To avoid confusion, "dihydroxy compound" in the present invention refers to the diol raw material in the prepolymerization stage of spandex, that is, the "dihydroxy compound" mentioned below does not include small molecule diols used as chain extenders and polyether diols used as raw materials for polyether ester diols. "Polyether diol" hereinafter refers to the polyether diol used to prepare polyether ester diols.

[0008] Furthermore, the molecular weight of the polyetherester diol is 800-5000.

[0009] Furthermore, the polyether segment in the polyether ester diol is a residue after the reaction of polyether diol with carboxyl group, and the polyether segment includes a first type of polyether segment and an optional second type of polyether segment, wherein the first type of polyether segment is at least one of polyethylene glycol residue, poly 1,3-propylene glycol residue, and poly 1,2-propylene glycol residue, and the second type of polyether segment includes a residue of polytetrahydrofuran. The "residue" mentioned here refers to the part remaining after the polyether diol reacts with carboxylic acid and the hydrogen atom of the terminal hydroxyl group is removed from the polyether diol. The molecular weights of the first type of polyether ester segment and the second type of polyether segment are both 100-2000.

[0010] Furthermore, the polyether ester diol is obtained by reacting dicarboxylic acid and polyether diol.

[0011] Furthermore, the molecular weight of the polyether diol is 100-2000.

[0012] Furthermore, the polyether diol includes a first type of polyether diol and an optional second type of polyether diol, wherein the first type of polyether diol is at least one of polyethylene glycol, poly 1,3-propylene glycol, and poly 1,2-propylene glycol, and the second type of polyether diol includes polytetrahydrofuran.

[0013] Furthermore, the mass ratio of the first type of polyether diol to the total polyether diol is 3-100%.

[0014] Furthermore, the mass ratio of the polyether chain segment in the polyether ester diol is 45-91%. The mass ratio refers to the mass ratio of the first and second polyether diol residues in the polyether ester diol after the polyether ester diol is prepared.

[0015] Furthermore, the dicarboxylic acid is at least one of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an alicyclic dicarboxylic acid.

[0016] A method for recycling nylon-spandex fabric, wherein the nylon-spandex fabric is the nylon-spandex fabric described above, characterized in that it comprises the following steps:

[0017] 1) immersing the nylon-spandex fabric in an alkali-alcohol solution to dissolve the spandex therein;

[0018] 2) Rinse the dissolved nylon-spandex fabric;

[0019] 3) Physical or chemical recovery of washed nylon;

[0020] Wherein, the alkali-alcohol solution comprises a small molecule alcohol and an alkali metal hydroxide, wherein the small molecule alcohol is an alcohol hydroxyl compound with a molecular weight less than 200, and can be a monofunctional small molecule alcohol or a difunctional alcohol, and preferably the small molecule alcohol is at least one of methanol or ethanol. The alkali metal is at least one of lithium, sodium, and potassium. Specifically, the alkali solution of the present invention is a small molecule alcohol solution of an alkali metal hydroxide, such as a n-butanol and / or ethylene glycol solution of sodium hydroxide and / or potassium hydroxide.

[0021] Furthermore, the proportion of small molecule alcohol in the alkali-alcohol solution is 60-95% by mass, and the proportion of alkali therein is 5-40%.

[0022] Furthermore, the alkali-alcohol solution consists of an alcohol hydroxyl compound with a molecular weight less than 200 and an alkali metal hydroxide.

[0023] Furthermore, in the step 1), during the dissolution process, the temperature is preferably lower than the boiling point of the selected alcohol, and the operation is performed at normal pressure.

[0024] Furthermore, in step 3), the nylon is further washed before recycling.

[0025] Beneficial effects:

[0026] In the nylon-spandex fabric of the present invention, the spandex contains a specific polyether ester segment, and the spandex can be decomposed by a specific alkali-alcohol solution during the fabric recycling process, while the nylon is retained, thereby preventing the spandex from becoming an impurity in the nylon recycling process. At the same time, the polyether ester segment with a specific structure provided by the present invention can greatly increase the reaction rate of the spandex and the alkali-alcohol solution, thereby improving the recycling efficiency of the nylon-spandex fabric. DETAILED DESCRIPTION

[0027] Nylon-spandex fabrics are widely used in clothing due to their advantages such as wear resistance and high elasticity. However, nylon and spandex are difficult to separate during the recycling process. During the recycling process, spandex will become an impurity that affects the quality of the recycled nylon. Therefore, the present invention provides an easily recyclable nylon-spandex fabric and a recycling method thereof.

[0028] Specifically, the present invention provides an easily recyclable nylon-spandex fabric, wherein the nylon-spandex fabric comprises nylon and spandex, wherein the dihydroxy compound raw material of the spandex comprises polyether ester diol, and the structure of the polyether ester diol comprises an ester bond and a polyether segment.

[0029] In the present invention, the nylon refers to polyamide fiber, also known as nylon, which is a general term for thermoplastic resins containing repeating amide groups on the molecular chain, including aliphatic polyamide, aromatic polyamide of aliphatic-aromatic polyamide. In the present invention, there is no special requirement for nylon, and common polyamide fibers on the market can be used as the nylon in the present invention, such as nylon 6, nylon 66, nylon 56, nylon 46, nylon 8, nylon 6-9, nylon 6-12, nylon 11, nylon 4T, nylon 6T, etc.

[0030] Spandex refers to polyurethane fiber. In the production of spandex, the raw materials used usually include diisocyanate, dihydroxy compound, chain extender and additives. First, diisocyanate and dihydroxy compound react to form prepolymer, then chain extender is added to react to obtain polyurethane, and finally additives are added and spun to obtain spandex. In the spandex molecule obtained, dihydroxy compound provides the soft segment of spandex, and diisocyanate and chain extender provide the hard segment of spandex.

[0031] Furthermore, the molecular weight of the polyether segment is greater than 100 and less than 2000.

[0032] If the molecular weight of the polyether segment is too small, the elasticity of the spandex will be affected, and if the molecular weight is too large, the stress of the spandex yarn will be too low. Preferably, the molecular weight of the polyether segment is greater than 200.

[0033] Preferably, the molecular structure of the polyetheresterdiol comprises the following structure:

[0034]

[0035] Among them, R1 is an aliphatic, alicyclic or aromatic group, and R2 is at least one of saturated alkane groups having 2 to 3 carbon atoms.

[0036] In the above formula, (R2-O) x The chain segment is a polyether chain segment, and the saturated alkane group with 2-3 carbon atoms between the ether oxygen bonds has excellent polarity, can promote the reaction between the polyether ester chain segment and the alkali-alcohol system, and improve the reaction efficiency. The chain segment is called the first type of polyether chain segment in the polyether ester diol in the present invention. In order to ensure the reaction ability of spandex in the alkali-alcohol system solution, the content of the first type of polyether chain segment in the polyether ester diol should exceed 3% to ensure that the final spandex can be degraded by breaking the ester bond of the above formula.

[0037] The molecular structure of the polyether ester diol may also contain some other types of polyethers, such as polytetrahydrofuran and other types of polyether segments usually used as raw materials for the soft segment. These polyether segments are referred to as the second type of polyether segments in the present invention. Preferably, the first type of polyether segments account for 3-100% of the total polyether segment mass. When the first type of polyether diol accounts for 100% of the total polyether diol mass, the amount of the second type of polyether diol added is 0.

[0038] Preferably, the mass proportion of the total polyether chain segments in the polyetherester diol is 45-91%.

[0039] In addition, the polyetherester diol may also contain some other polyester structures that can be used as spandex soft segments, or aliphatic structures and aromatic structures used to modify spandex, etc. These structures are not essential for the present invention.

[0040] Preferably, the molecular weight of the polyetherester diol is 1000-5000.

[0041] The polyether ester diol is obtained by reacting a dicarboxylic acid with a polyether diol. Preferably, the polyether diol is at least one of polyethylene glycol, poly 1,3-propylene glycol, and poly 1,2-propylene glycol. Preferably, the dicarboxylic acid is at least one of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an alicyclic dicarboxylic acid. The aliphatic dicarboxylic acid is a general term for chain hydrocarbons (open-chain hydrocarbons) and cyclic hydrocarbons other than aromatic compounds and their derivatives. In addition to carbon and hydrogen, it may also contain oxygen, nitrogen, sulfur, chlorine and other elements. The optional aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, sebacic acid, and dodecanedioic acid. etc.; Aromatic refers to substances with aromatic rings or aromatic heterocycles in their molecular structures. Optional aromatic dicarboxylic acids include terephthalic acid, phthalic acid, isophthalic acid, biphenyl dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,5-furan dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, etc.; Alicyclic refers to a molecule containing a carbon ring connected by 3 or more carbon atoms, and the two adjacent carbon atoms in the ring can be a single bond, a double bond or a triple bond, and the number of rings can be one or more, such as 1,4-cyclohexane dicarboxylic acid, etc.

[0042] In actual production, the polyether diol can also be a product of polymerization of multiple small molecule diols, such as polyether diols formed by polymerization of at least two of ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol. Under the condition of ensuring the density of ether oxygen bonds in polyether ester, it is also allowed to add a small amount of small molecule diols with more carbon atoms such as butanediol in the production of polyether diol, but these types of polyether diols are not economical in production. Therefore, the polyether diol used as a raw material in the present invention is preferably polyethylene glycol, poly 1,3-propylene glycol, and at least one of poly 1,2-propylene glycol, and polyethylene glycol is most preferred. These polyether diols are referred to as the first type of polyether diols in this application, and the first type of polyether diols are essential for the present invention. In addition, the raw materials for preparing polyether ester diols can also include other types of polyether diols such as polytetrahydrofuran ether diol, which are used to improve the mechanical properties of spandex. These polyether diols are referred to as the second type of polyether diols in the present invention.

[0043] Preferably, the polyether ester diol can be prepared by reacting the polymer diol, dicarboxylic acid and other optional raw materials. The present invention does not make specific requirements on the equipment and process used for the reaction, as long as the polyether ester diol meeting the above requirements can be obtained. In a specific embodiment, the polyether diol is obtained by reacting polyethylene glycol, polytetrahydrofuran and dicarboxylic acid, and the preparation process of the polyether ester diol is as follows:

[0044] Put polyether diol (including polyethylene glycol and polytetrahydrofuran) and dicarboxylic acid into a reactor, pass nitrogen to replace the air in the reactor, start stirring the reactor, program the system to heat up, keep it for a period of time, continue to heat up, and keep it warm until the water output rate of the system reaches more than 90% of the theoretical value and the solution becomes homogeneous, add a catalyst, and gradually evacuate. When the acid value is lower than 0.5 mgKOH / g, polyether ester diol is obtained.

[0045] Using the above polyether ester diol as raw material, polyether ester type spandex can be prepared by the following steps:

[0046] Add the obtained polyether ester diol to a reactor that has been kept at a constant temperature of 45°C and start stirring. Add a diisocyanate compound, stir for 5 minutes, and then heat it to 90°C; react it at 90°C for 2 hours to obtain a prepolymer. Cool the prepolymer to 50°C, use dimethylacetamide to dissolve the prepolymer, and then add an amine solution with a mass concentration of 3% containing a chain extender and a chain terminator (such as amine substances such as ethylenediamine and diethylamine) to carry out a chain extension reaction. After the chain extension reaction is completed, add necessary antioxidants, dyeing agents and other auxiliaries, and mature for 30 hours to obtain a spinning solution with a solid content of 35%. The above solution is dry-spun to obtain a polyurethane elastic fiber with a denier of 40D, namely spandex.

[0047] In the nylon-spandex fabric of the present invention, a polyether ester diol containing a specific polyether segment is selected as the dihydroxy compound raw material of spandex, and a polyether ester structure containing the specific polyether segment is introduced into the spandex soft segment. The ester bond-polyether structure can provide sufficient elasticity for the spandex, and the ester bond is easy to break in an alkali-alcohol environment, which can make the spandex quickly decompose under relatively mild conditions, so that the spandex is easily removed from the nylon-spandex fabric to obtain a single component of nylon, which is convenient for further recycling of the nylon. Compared with ordinary polyester-type spandex, the polyether ester diol containing the specific polyether segment has better polarity, and the spandex prepared by the polyether ester spandex has a faster decomposition rate in an alkali-alcohol environment than the traditional polyether ester spandex prepared by polytetrahydrofuran and the polyester spandex prepared by polyester diol, which can improve the recycling efficiency of the fabric.

[0048] In the present invention, the dihydroxy compound raw material of spandex may be a mixture of the polyether ester diols described above and other polyether dihydroxy compounds or polyester dihydroxy compounds. The above-mentioned polyether ester diols play a role in promoting the decomposition of spandex in spandex. Specifically, other polyether dihydroxy compounds may be polytetrahydrofuran ether diols, and polyester dihydroxy compounds may be polyethylene adipate glycol ester diol, polybutylene adipate glycol ester diol, polyester dihydroxy compounds prepared from adipic acid and mixed low molecular weight diols, or polyether ester diols synthesized using polytetrahydrofuran. Preferably, the polyether ester diols described in the present invention account for more than 50% of all dihydroxy compound raw materials, preferably more than 75%, and preferably 100%.

[0049] The present invention also provides a method for recycling nylon-spandex fabric, wherein the nylon-spandex fabric is the nylon-spandex fabric described above, and the method is characterized in that the method comprises the following steps:

[0050] 1) immersing the nylon-spandex fabric in an alkali-alcohol system solution to react and decompose the spandex therein;

[0051] Specifically, when there are other debris in the fabric, the fabric can be sorted in advance according to the situation.

[0052] The alkali-alcohol solution of the present invention is a mixture of small-molecule alcohol and alkali metal hydroxide, and the purpose is to make the ester bond in the spandex undergo alcoholysis in the alkali-alcohol environment, thereby playing a role in decomposing the spandex in the nylon-spandex fabric. The molecular alcohol is preferably an alcohol hydroxyl compound with a molecular weight below 200. If the molecular weight of the alcohol compound is too high, the solubility of the alkali metal in the alcohol is poor. Specifically, the small-molecule alcohol in the present invention can be a monofunctional pure alcohol such as methanol, ethanol, propanol, butanol, or ethylene glycol, propylene glycol, diethylene glycol, etc., preferably methanol and ethanol. Alcohol substances with smaller molecular weights have higher reaction rates and lower boiling points, and are easy to recover by distillation. Other mutually soluble substances such as water, ammonia, tetrahydrofuran, DMAc, etc. can also be present in the alkali-alcohol system solution.

[0053] Specifically, the alkali-alcohol solution can be prepared from the following substances: small molecule alcohols and alkali metal hydroxides, and substances that are miscible with the above system, such as water, ammonia water, tetrahydrofuran, DMAc, etc.

[0054] The decomposition reaction of spandex is carried out at a temperature below the boiling point of small molecule alcohols and at normal pressure. Since small molecule alcohols have a strong attack on the above-mentioned polyether ester segments with strong polarity, the ester groups of the polyether ester segments with strong polarity are more likely to decompose under alkali-alcohol conditions to form segments ending with alcohols (i.e., alcohol products) and form alkali metal salts with dicarboxylic acid residues.

[0055] 2) washing the nylon-spandex fabric after the reaction;

[0056] After dissolving in step 1), the spandex in the nylon-spandex fabric is decomposed into alcohol products, dicarboxylates and spandex polymer residues, wherein the alcohol products and dicarboxylates are dissolved in the liquid, and the spandex polymer residues are present in the system in the form of fine particles. Nylon has good resistance in the alkali-alcohol system, so the nylon in the fabric can basically maintain the original fabric structure. The fabric after the reaction is rinsed, and the decomposition products of the spandex are separated from the fabric in the form of liquid or fine particles along with the alkali-alcohol system solution, thereby obtaining nylon without spandex polymer.

[0057] 3) Physical or chemical recovery of the filtered nylon;

[0058] After rinsing, the fabric obtained has basically only nylon left, and the rinsed nylon can be further washed to remove the residual reaction liquid and fine particles on the surface. The washed nylon can be used for the next step of nylon recovery.

[0059] Specifically, nylon can be recycled physically through melt regeneration and granulation; it can also be recycled chemically by causing the polymer materials in nylon to undergo degradation reactions under the action of heat and chemical reagents to form products with lower molecular weight such as caprolactam, dibasic acids, diamines, etc., which can be further recycled.

[0060] Example

[0061] The present invention is described in more detail by way of examples. In each of the examples below, the weight loss rate of the fabric is greater than the spandex content in the fabric, which may be caused by the fact that some oil-like substances in the fabric are washed away. Therefore, in the present invention, whether the spandex is completely decomposed is determined by observing the typical urea carbonyl infrared absorption peak of spandex.

[0062] Examples 1-4 relate to nylon-spandex fabrics.

[0063] Example 1

[0064] A nylon-spandex fabric is blended by nylon 66 and spandex in a circular knitting form, wherein nylon accounts for 80% and spandex accounts for 20%, and the spandex is prepared in the following manner:

[0065] 1 part by weight of polyethylene glycol PEG600 (number average molecular weight 600), 16 parts by weight of polytetrahydrofuran PTG650 (number average molecular weight 650) and 2.8 parts by weight of terephthalic acid are reacted to obtain a polyether ester diol with a number average molecular weight of 2050.

[0066] The above polyether ester diol is reacted with diphenylmethane diisocyanate to obtain a prepolymer. After the prepolymer is cooled, it is dissolved with dimethylacetamide, and then a 3% amine solution is added to carry out a chain extension reaction. After the chain extension reaction is completed, necessary antioxidants, dyeing agents and other auxiliaries are added, and then ripened to obtain a spinning solution with a solid content of 35%. The above solution is dry-spun to obtain a polyurethane elastic fiber with a denier of 40D, namely spandex. The soft segment of the spandex contains a benzene ring and a polyethylene glycol residue structure connected by an ester bond (the polyethylene glycol residue structure is a straight-chain alkane with 2 carbon atoms between the ether oxygen bonds).

[0067] Example 2

[0068] A nylon-spandex fabric is blended by nylon 6 and spandex in a warp knitting form, wherein nylon accounts for 84% and spandex accounts for 16%, and the spandex is prepared by the following method:

[0069] 17 parts by weight of polypropylene glycol PPG950 (number average molecular weight of 950) and 2.1 parts by weight of terephthalic acid were reacted to obtain a polyether ester diol having a number average molecular weight of 3600.

[0070] The above-mentioned polyetheresterdiol is spun into spandex with a denier of 40D in the same manner as in Example 1, wherein the soft segment of the spandex is a benzene ring and a poly(1,3-propylene glycol) residue structure connected by ester bonds (the poly(1,3-propylene glycol) residue structure is a straight-chain alkane with 3 carbon atoms between the ether oxygen bonds).

[0071] Example 3

[0072] A nylon-spandex fabric is blended by nylon 56 and spandex in a circular knitting machine, wherein nylon accounts for 90% and spandex accounts for 10%, and the spandex is prepared by the following method:

[0073] 17 parts by weight of polyethylene glycol PEG600 (number average molecular weight 600) and 2.9 parts by weight of adipic acid were reacted to obtain a polyether ester diol with a number average molecular weight of 2300.

[0074] The polyetheresterdiol is spun into 40D spandex in the same manner as in Example 1, wherein the soft segment of the spandex is a structure of 4 methylene groups and polyethylene glycol residues connected by ester bonds (the polyethylene glycol residue structure is a straight-chain alkane with 2 carbon atoms between ether oxygen bonds).

[0075] Example 4

[0076] A nylon-spandex fabric is blended by nylon 6-12 and spandex in a circular knitting form, wherein the nylon accounts for 70% and the spandex accounts for 30%, and the spandex is prepared in the following manner:

[0077] 5 parts by weight of polyethylene glycol PEG600 (number average molecular weight 600), 12 parts by weight of poly 1,3-propylene glycol PPG950 (molecular weight 950) and 1.8 parts by weight of terephthalic acid are reacted to obtain a polyether ester diol with a number average molecular weight of 2300.

[0078] The polyetherester diol is spun into a spandex with a denier of 40D in the same manner as in Example 1, wherein the soft segment of the spandex is a benzene ring and a polyether structure connected by an ester bond (the polyether structure is a residue of a straight-chain alkane with a carbon number of 2 and a 1,3-propylene glycol with a carbon number of 3 between the ether oxygen bonds)

[0079] Examples 5-8 relate to a method for recycling nylon-spandex fabrics.

[0080] Example 5

[0081] The nylon-spandex fabric described in Example 1 was immersed in an alkali-alcohol system solution, wherein the alkali-alcohol system solution was prepared by 90 parts by mass of methanol and 10 parts by mass of sodium hydroxide, and reacted at 50°C for 30 minutes to degrade the fabric. The fabric after the reaction was thoroughly washed, dried and weighed, and the weight loss rate of the fabric after the reaction was 22.3%. The fabric before and after the alkali-alcohol solution treatment was subjected to ATR mode infrared testing, and it was found that the typical spandex yarn had a 1713cm -1 The mixed absorption peaks of carbamate carbonyl and polyether ester carbonyl have disappeared, indicating that the spandex has been completely decomposed and removed by the alkali alcohol solution in this process. The washed nylon fabric with spandex removed is crushed and melt-cut to obtain regenerated nylon chips.

[0082] Example 6

[0083] The nylon-spandex fabric described in Example 2 was immersed in an alkali-alcohol system solution, wherein the alkali-alcohol system solution was prepared by 90 parts by mass of ethanol and 10 parts by mass of potassium hydroxide, and reacted at 60°C for 35 minutes to degrade the fabric. The fabric after the reaction was thoroughly washed, dried and weighed, and the weight loss rate of the fabric after the reaction was 18.2%. The fabric before and after the alkali-alcohol solution treatment was subjected to ATR mode infrared testing, and it was found that the typical spandex yarn had a 1713cm -1 The mixed absorption peak of carbamate carbonyl and polyether ester carbonyl has disappeared, indicating that the spandex has been completely decomposed and removed by the alkali alcohol solution in this process. After washing, the nylon fabric with spandex removed is crushed and melt-cut to obtain regenerated nylon chips.

[0084] Example 7

[0085] The nylon-spandex fabric described in Example 3 was immersed in an alkali-alcohol system solution, wherein the alkali-alcohol system solution was prepared by 50 parts by mass of ethanol, 40 parts by mass of water, and 10 parts by mass of potassium hydroxide, and reacted at 60°C for 40 minutes to degrade the fabric. The fabric after the reaction was thoroughly washed, dried and weighed, and the weight loss rate of the fabric after the reaction was 11.3%. The fabric before and after the alkali-alcohol solution treatment was subjected to ATR mode infrared testing, and it was found that the typical spandex yarn had a 1713cm -1 The mixed absorption peak of carbamate carbonyl and polyether ester carbonyl has disappeared, indicating that the spandex has been completely decomposed and removed by the alkali alcohol solution in this process. After washing, the nylon fabric fragments without spandex are chemically recovered to obtain pentamethylenediamine and adipic acid.

[0086] Example 8

[0087] The nylon-spandex fabric described in Example 4 was immersed in an alkali-alcohol system solution, wherein the alkali-alcohol system solution was prepared by 90 parts by mass of ethylene glycol and 10 parts by mass of sodium hydroxide, and reacted at 70°C for 40 minutes to degrade the fabric. The fabric after the reaction was thoroughly washed, dried and weighed, and the weight loss rate of the fabric after the reaction was 31.5%. The fabric before and after the alkali-alcohol solution treatment was subjected to ATR mode infrared testing, and it was found that the typical spandex yarn had a 1713cm -1 The mixed absorption peak of carbamate carbonyl and polyether ester carbonyl has disappeared, indicating that the spandex has been completely decomposed and removed by the alkali alcohol solution in this process. After washing, the nylon fabric fragments without spandex are chemically recovered to obtain hexamethylenediamine and 1,12-dodecane dioic acid.

[0088] Comparative Example 1

[0089] The nylon-spandex fabric used in this comparative example is similar to the nylon-spandex fabric of Example 1, except that the polyether used to prepare the polyether ester is replaced by 1 part by weight of PTG650 instead of polyethylene glycol.

[0090] The nylon-spandex fabric was treated with an alkali-alcohol solution in the manner described in Example 5. After the reaction, the weight loss rate of the fabric was 6.5%. After infrared detection, the typical 1713cm -1 The mixed absorption peaks of carbamate carbonyl and polyether ester carbonyl still exist. The slices prepared using the treated fabric have a darker color, showing a distinct brownish yellow color, indicating that the spandex is not treated cleanly, and residual components of spandex remain in the prepared slices, which significantly reduces the quality of the slices.

[0091] Comparative Example 2

[0092] The nylon-spandex fabric used in this comparative example is similar to the nylon-spandex fabric of Example 1, except that the polyol used to prepare spandex is replaced by traditional polytetrahydrofuran.

[0093] The nylon-spandex fabric was recycled in the manner described in Example 5. After the reaction, the weight loss rate of the fabric was 0.5%. After infrared detection, the typical urea carbonyl infrared absorption peak of spandex was basically similar to the infrared spectrum of the original fabric, indicating that the spandex yarn prepared using traditional polytetrahydrofuran is hardly degraded in this process.

[0094] Comparative Example 3

[0095] The nylon-spandex fabric used in this comparative example is similar to the nylon-spandex fabric of Example 3, except that the polyether used to prepare the polyetherester is prepared from 1 part by mass of ethylene glycol, 16 parts by mass of PTG650 and 5.4 parts by mass of PTA.

[0096] The nylon-spandex fabric was treated with an alkali-alcohol solution in the manner described in Example 7. After the reaction, the weight loss rate of the fabric was 2.6%. According to infrared detection, the typical 1713 cm -1 The mixed absorption peak of carbamate carbonyl and polyether ester carbonyl still exists, and the peak height is relatively high, indicating that the spandex prepared by using traditional polytetrahydrofuran and small molecule diol to prepare polyether ester diol and then using the obtained polyether ester diol will not be completely degraded in this process. The slices prepared by using the treated fabric have a darker color, showing a distinct reddish brown, indicating that the spandex is not mostly treated cleanly, and residual components of spandex remain in the prepared slices, which significantly reduces the quality of the slices.

[0097] The experimental results of the above embodiments are summarized in the following table.

[0098]

[0099]

[0100] As can be seen from the above table, compared with conventional nylon-spandex fabrics, the nylon-spandex fabric provided by the present invention can completely decompose the spandex in an alkali-alcohol system solution using the fabric containing the polyether-ester spandex of the present invention, significantly reducing the impurities present in the nylon recovery process. Moreover, under the same recovery process and within the same processing time, the polyether-ester spandex provided by the present invention can be completely decomposed, while conventional nylon-spandex fabrics are difficult to completely decompose, which indicates that the decomposition rate of the spandex provided by the present invention is faster, and the recovery efficiency of the nylon-spandex fabric is improved.

Claims

1. An easily recyclable nylon-spandex fabric, comprising nylon and spandex, characterized in that: The dihydroxy compound raw material of the spandex includes polyether ester diol, and the structure of the polyether ester diol includes ester bonds and polyether segments.

2. The easily recyclable nylon-spandex fabric according to claim 1, characterized in that: The polyether segment in the polyetherester diol is a residue after the reaction of polyether diol and carboxyl group, and the polyether segment includes a first type of polyether segment and an optional second type of polyether segment, the first type of polyether segment is at least one of polyethylene glycol residue, poly 1,3-propylene glycol residue, and poly 1,2-propylene glycol residue, and the second polyether diol includes a residue of polytetrahydrofuran.

3. The easily recyclable nylon-spandex fabric according to claim 1, characterized in that: The molecular weights of the first type of polyether diol and the second type of polyether diol are both 100-2000.

4. The easily recyclable nylon-spandex fabric according to claim 3, characterized in that: The polyether ester diol is obtained by reacting dicarboxylic acid and polyether diol. The polyether diol includes a first type of polyether diol and an optional second type of polyether diol. The first type of polyether diol is at least one of polyethylene glycol, poly 1,3-propylene glycol, and poly 1,2-propylene glycol. The second type of polyether diol includes polytetrahydrofuran. The first type of polyether diol accounts for 3-100% of the total polyether diol mass.

5. The easily recyclable nylon-spandex fabric according to claim 1, characterized in that: The mass proportion of the polyether segment in the polyether ester diol is 45-91%.

6. The easily recyclable nylon-spandex fabric according to claim 4, characterized in that: The dicarboxylic acid is at least one of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an alicyclic dicarboxylic acid.

7. A method for recycling nylon-spandex fabric, wherein the nylon-spandex fabric is the nylon-spandex fabric according to any one of claims 1 to 6, characterized in that: The steps include: 1) immersing the nylon-spandex fabric in an alkali-alcohol solution to dissolve the spandex therein; 2) Rinse the dissolved nylon-spandex fabric; 3) Physical or chemical recovery of washed nylon; The alkali-alcohol solution comprises a small molecule alcohol and an alkali metal hydroxide, and the small molecule alcohol is an alcohol hydroxyl compound with a molecular weight less than 200.

8. The method for recycling nylon-spandex fabric according to claim 7, characterized in that: The small molecule alcohol is at least one of methanol or ethanol.

9. The method for recycling nylon-spandex fabric according to claim 7, characterized in that: The proportion of small molecule alcohol in the alkali-alcohol solution is 60-95% by mass, and the proportion of alkali therein is 5-40% by mass.

10. The method for recycling nylon-spandex fabric according to claim 7, characterized in that: In the step 1), during the dissolution process, the process temperature is lower than the boiling point of the alcohol in the alkali-alcohol solution, and the reaction pressure is normal pressure.

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