Spandex with yellowing resistance and preparation method thereof

Abstract

The present invention provides a spandex with yellowing resistance and a preparation method thereof. The spandex comprises a polyurethane-urea reaction product obtained from a polyether polyol, a polyisocyanate, and a mixed amine, wherein the polyurethane-urea reaction product has a terminal amine group content of less than 2 mmol / kg. The preparation method comprises dry spinning using the polyurethane-urea reaction product as a spinning solution; the spinning solution comprises the polyurethane-urea reaction product and a solvent, and the total terminal amine group content of the spinning solution is 2 to 6 mmol / kg, calculated based on the solid content of the spinning solution. The product prepared thereby has excellent yellowing resistance, can solve the problem of deterioration of spandex-containing fabrics during storage and use, and improve the performance and service life of spandex-containing fabrics.

Description

Technical Field

[0001] The present invention relates to a spandex with yellowing resistance and a preparation method thereof, belonging to the field of polyurethane elastic fibers. The spandex fiber prepared by the present invention has excellent light stability, heat resistance, yellowing resistance, and weather resistance, thereby preventing fabric degradation during storage and use and improving the performance and service life of spandex-containing fabrics. Background Art

[0002] Spandex is widely used in daily fabrics and is an indispensable member of modern fabrics. However, spandex-containing elastic fabrics are inevitably affected by light, heat, acids, alkalis, chlorine water and other substances during storage, sales, wearing and washing, causing the performance of spandex fibers to deteriorate. Spandex molecules contain ether bonds, amide bonds, carbamate bonds and other groups. These groups will undergo photolysis, thermal decomposition, oxidation and other chemical reactions under the influence of light, heat, acids, alkalis and active chlorine, resulting in the destruction and cracking of the molecular chain. The main reasons for yellowing are as follows: (1) Yellowing caused by the spandex raw materials themselves: Polymer polyols, polyisocyanates, small molecular amines and other raw materials generally contain BHT (2,6-di-tert-butyl-p-cresol), and active groups remain in the fiber during the production process, which reacts chemically with nitrogen oxides in the air, thereby causing yellowing. (2) Yellowing during packaging and storage: Packaging materials such as polyethylene (or polystyrene) contain antioxidants (mainly BHT). Since BHT has a low solubility in polyethylene and is easily volatile, it will diffuse onto the surface of the packaging material, forming a yellow substance. (3) Yellowing during the weaving process, wearing, and washing: Spandex is prone to yellowing due to sunlight, temperature changes, etc.

[0003] Over the years, numerous researchers and corporate engineers have conducted extensive research in this area. For example, physical modification—adding light stabilizers or antioxidants—is one of the simplest approaches to addressing photoaging. Patent CN105483856A discloses a method for producing UV-resistant spandex through in-situ polymerization. This method allows the UV-resistant additive to chemically bond to the spandex molecules, stably. Results show that the UV-resistant spandex produced using this method exhibits more durable UV resistance. However, this technology only provides limited improvements in certain aspects of spandex's performance and does not fundamentally address the yellowing issue. Patent CN101736432A discloses a method for producing yellowing-resistant polyurethane elastic fibers. During the prepolymerization process, isophorone diisocyanate (equivalent to 0.5-10% of the total isocyanate content) is added to reduce the presence of unsaturated double bonds in the polymer. However, this small amount of isophorone diisocyanate only provides a limited improvement; the polymer still yellows due to UV exposure and oxidation, failing to fundamentally address the yellowing issue. Patent CN110685034A discloses a method for preparing phenol yellowing-resistant spandex fiber, in which the anti-phenol yellowing agent is chemically bonded by an in-situ polymerization method. The phenol yellowing resistance performance does not decrease after multiple water washings. This technology is indeed helpful in solving the problem of durability, but it will destroy the molecular structure of the spandex itself and have a certain impact on its mechanical properties.

[0004] In summary, spandex yellowing is influenced by a variety of factors, which, to a certain extent, reduces spandex quality, particularly challenging the fiber's durability. While maintaining essentially unchanged polyurethane elastic fiber properties, the present invention not only enhances the spandex fiber's bright white color without yellowing, but also fundamentally resolves the yellowing problem of polyurethane elastic fiber during weaving and wearing. Summary of the Invention

[0005] Technical problem: The purpose of the present invention is to provide a spandex with yellowing resistance and a preparation method thereof. The product prepared therefrom has excellent yellowing resistance, can solve the deterioration of spandex-containing fabrics during storage and use, and improve the performance and service life of spandex-containing fabrics.

[0006] Technical solution: The present invention provides a spandex with yellowing resistance, which contains a polyurethane-urea reaction product obtained by polyether polyol, polyisocyanate and mixed amine, and the terminal amine content of the polyurethane-urea reaction product is less than 2 mmol / kg.

[0007] The spandex further comprises an anti-yellowing agent, wherein the main antioxidant in the anti-yellowing agent comprises one or more of a hydroxylamine antioxidant, a tertiary amine antioxidant, and a furanone antioxidant; the content of the anti-yellowing agent is 0.1 to 5%, calculated based on the mass of the spandex;

[0008] Preferably, the primary antioxidant specifically includes one or more of antioxidant 953, antioxidant Revonox 420, antioxidant Revonox 501, antioxidant Revonox 501, antioxidant DBHA, and antioxidant 264.

[0009] The polyether polyol includes one or more of polytetramethylene glycol polyol, polyethylene glycol polyol and polypropylene glycol polyol.

[0010] The polyisocyanate includes one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and / or derivatives and / or modified polymers.

[0011] The mixed amine comprises a chain extender diamine and a capping agent monoamine, wherein the diamine comprises one or more of ethylenediamine, propylenediamine, butylenediamine and pentamethylenediamine; the monoamine comprises one or more of diethylamine, dipropylamine and n-hexylamine; and the molar ratio of the diamine to the monoamine is 5:1 to 1:1.

[0012] The anti-yellowing additive further includes a secondary antioxidant, including a phosphate secondary antioxidant and / or a thioester secondary antioxidant, specifically including one or more of antioxidant 948, antioxidant 168, and antioxidant 412S.

[0013] The anti-yellowing additive further comprises an anti-nitrogen oxide agent; the anti-nitrogen oxide agent comprises at least one of GA-80 and HN-130; the content of the anti-nitrogen oxide agent is 0.1-1.5% based on the mass of the spandex.

[0014] The anti-yellowing additive further includes an anti-ultraviolet absorber, and the ultraviolet absorber includes one or more of salicylate ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, triazine ultraviolet absorbers, and formamidine ultraviolet absorbers.

[0015] Preferably, the anti-ultraviolet absorber includes one or more of UV-3030, UV-903, UV-123, UV3853, UV-1, and UV-T; and the content of the anti-ultraviolet absorber is 0.1 to 1.5% based on the mass of the spandex.

[0016] The method for preparing spandex with yellowing resistance of the present invention uses the polyurethane-urea reaction product as a spinning solution and obtains the spandex through dry spinning.

[0017] The spinning solution comprises a polyurethane-urea reaction product and a solvent, and the total terminal amino group content of the spinning solution is 2 to 6 mmol / kg, calculated based on the solid content of the spinning solution;

[0018] The preparation method is as follows:

[0019] 1) carrying out a prepolymerization reaction of polyisocyanate and polyether polyol in the presence of a solvent to prepare a polyurethane prepolymer solution;

[0020] 2) reacting a polyurethane prepolymer solution with a mixed amine solution to obtain a stock solution containing a polyurethane-urea reaction product;

[0021] 3) After the stock solution containing the polyurethane-urea reaction product is aged, the aged polyurethane-urea stock solution is used as a spinning solution to obtain spandex fiber with yellowing resistance through dry spinning technology.

[0022] Beneficial effects: The spandex with yellowing resistance of the present invention has excellent resistance to nitrogen oxide yellowing by controlling the terminal amine content of the polyurethane-urea reaction product. In addition, by compounding with a specific anti-yellowing agent, the spandex's resistance to nitrogen oxide yellowing and light yellowing are further improved, the fiber has a bright white color, and the mechanical properties of the spandex fiber of the present invention are guaranteed not to deteriorate and it will not turn yellow after long-term use. The yellowing resistance is far superior to similar products. DETAILED DESCRIPTION

[0023] The present invention provides a spandex with yellowing resistance, which contains a polyurethane-urea reaction product obtained by polyether polyol, polyisocyanate and mixed amine, wherein the terminal amine content of the polyurethane-urea reaction product is 0 to 2 mmol / kg;

[0024] Furthermore, the spandex with yellowing resistance comprises a polyurethane-urea reaction product obtained by reacting polyether polyol and polyisocyanate to obtain a polyurethane prepolymer and a mixed amine;

[0025] The mixed amine includes a chain extender diamine and a capping agent monoamine, the diamine includes one or more of ethylenediamine, propylenediamine, butylenediamine, and pentamethylenediamine, and the monoamine includes one or more of diethylamine, dipropylamine, and n-hexylamine;

[0026] The molar ratio of the diamine to the monoamine is 5:1 to 1:1.

[0027] The polyether polyol includes one or more of polytetramethylene glycol polyol, polyethylene glycol polyol and polypropylene glycol polyol;

[0028] The polyisocyanate includes one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and / or derivatives and / or modified polymers;

[0029] The spandex with yellowing resistance contains 0.1-5% of an anti-yellowing agent, preferably 0.5-3% of an anti-yellowing agent, calculated based on the mass of the spandex;

[0030] Furthermore, the anti-yellowing additive includes a primary antioxidant, and the primary antioxidant includes one or more of a hydroxylamine antioxidant, a tertiary amine antioxidant, and a furanone antioxidant;

[0031] Preferably, the antioxidant includes one or more of antioxidant 953, antioxidant Revonox420, antioxidant Revonox501, antioxidant DBHA, and antioxidant 264;

[0032] Furthermore, the antioxidant further comprises a phosphate auxiliary antioxidant and / or a thioester auxiliary antioxidant, including one or more of antioxidant 948, antioxidant 168, and antioxidant 412S;

[0033] In some embodiments of the present invention, the primary antioxidant is not a hindered phenol antioxidant or a primary amine antioxidant alone;

[0034] Preferably, the antioxidant content is 0.1-3%, calculated based on the mass of spandex;

[0035] Furthermore, the anti-yellowing additive includes an anti-nitrogen oxide agent;

[0036] The anti-nitrogen oxide agent includes one or more of GA-80 and HN-130;

[0037] The content of the anti-nitrogen oxide agent is 0.1-1.5%, calculated based on the mass of the spandex.

[0038] Furthermore, the anti-yellowing additive includes an anti-ultraviolet absorber, and the ultraviolet absorber includes one or more of a salicylate ultraviolet absorber, a benzotriazole ultraviolet absorber, a substituted acrylonitrile ultraviolet absorber, a triazine ultraviolet absorber, and a formamidine ultraviolet absorber;

[0039] In some embodiments of the present invention, the ultraviolet absorber includes one or more of a salicylate ultraviolet absorber, a substituted acrylonitrile ultraviolet absorber, a triazine ultraviolet absorber, and a formamidine ultraviolet absorber;

[0040] Preferably, the anti-ultraviolet absorber includes one or more of UV-3030, UV-903, UV-123, UV-3853, UV-1, and UV-T;

[0041] The content of the anti-ultraviolet absorber is 0.1-1.5%, calculated based on the mass of the spandex.

[0042] Optionally, the yellowing-resistant spandex is added with titanium dioxide and / or a fluorescent whitening agent to improve the chromaticity of the spandex fiber;

[0043] The fluorescent whitening agent includes a triazine amino stilbene fluorescent whitening agent;

[0044] The titanium dioxide content is 0.1% to 1%, calculated based on the mass of spandex;

[0045] The content of the fluorescent whitening agent is 10ppm to 10000ppm, calculated based on the mass of the spandex.

[0046] The present invention provides a method for preparing spandex with yellowing resistance, which is obtained by dry spinning using the polyurethane-urea reaction product as a spinning solution;

[0047] Preferably, the spinning solution contains a polyurethane-urea reaction product and a solvent, and the total amino group content of the spinning solution is 2 to 6 mmol / kg, calculated based on the solid content of the spinning solution;

[0048] The solvent includes one or more of N,N-dimethylacetamide DMAc, N-methyl-2-pyrrolidone NMP, and dimethylformamide DMF;

[0049] The mass concentration of the spinning solution is 30%wt to 40%wt;

[0050] The viscosity of the spinning solution is 3000 to 12000 poise.

[0051] In some embodiments of the present invention, the method for preparing spandex having yellowing resistance comprises:

[0052] 1) carrying out a prepolymerization reaction of polyisocyanate and polyether polyol in the presence of a solvent to prepare a polyurethane prepolymer solution;

[0053] 2) reacting a polyurethane prepolymer solution with a mixed amine solution to obtain a stock solution containing a polyurethane-urea reaction product;

[0054] 3) After the stock solution containing the polyurethane-urea reaction product is aged, the aged polyurethane-urea stock solution is used as a spinning solution to obtain spandex fiber with yellowing resistance through dry spinning technology.

[0055] The dry spinning technology includes the steps of spraying, stretching, drying, false twisting and winding into yarn;

[0056] Preferably, a spandex oil agent may be coated on the surface of the spandex after the false twisting step, wherein the spandex oil agent includes a hydrophilic silicone oil, such as polyether-modified polysiloxane or amino-modified polysiloxane.

[0057] The mass concentration of the spinning solution is 30%wt to 40%wt;

[0058] The viscosity of the spinning solution is 3000 to 12000 poise;

[0059] The total amino content of the spinning solution is 2-6 mmol / kg. Controlling the total amino content of the spinning solution within a lower range can reduce the reaction between active groups and nitrogen oxides and avoid yellowing.

[0060] The molar ratio of diamine to monoamine in the mixed amine is 5:1 to 1:1, which can regulate the viscosity of the spinning solution within an appropriate range to improve the spinning effect of spandex and also improve the yellowing resistance of spandex.

[0061] The NCO content of the polyurethane prepolymer is 2.5-3.5wt%.

[0062] Furthermore, in some embodiments of the present invention, the anti-yellowing agent, the optional titanium dioxide, and the optional fluorescent whitening agent are added in step 3);

[0063] As an example, the anti-yellowing agent, optional titanium dioxide, and optional fluorescent brightener may be dispersed in a solvent and added in step 3).

[0064] Furthermore, the spandex may be added with other functional additives commonly used in the art, as long as they do not deteriorate the performance of the product, such as one or more of lubricants, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries.

[0065] The following examples are used to describe the production process of the present invention in detail, but these examples should not be construed as limiting the present invention in any sense.

[0066] Example

[0067] The method for preparing spandex with yellowing resistance comprises:

[0068] 1) performing a prepolymerization reaction of diphenylmethane diisocyanate and polytetramethylene ether polyol in the presence of DMAc to prepare a polyurethane prepolymer solution;

[0069] 2) reacting a polyurethane prepolymer solution with a mixed amine solution to obtain a stock solution containing a polyurethane-urea reaction product;

[0070] 3) After the stock solution containing the polyurethane-urea reaction product is aged, an optional anti-yellowing agent is added, and the aged polyurethane-urea stock solution is used as a spinning solution to obtain a spandex fiber with yellowing resistance by dry spinning technology, wherein the spandex fiber has a denier of 44 dtex.

[0071] Please see Table 1, Table 2 and Table 3 below for details of the embodiments and comparative examples:

[0072] Table 1:

[0073]

[0074]

[0075] Table 2:

[0076]

[0077]

[0078] Table 3:

[0079]

[0080] Among them, the terminal amine group test method of the polyurethane-urea reaction product is as follows: the original solution containing the polyurethane-urea reaction product is coated and placed in an oven for drying to completely evaporate the free small molecule amines and the solvent DMAc. The dried film is then dissolved in DMAc, di-n-butylamine is added, and after stirring evenly, the film is titrated with methanesulfonic acid solution to obtain the amine group content.

[0081] The total amino content test method of the spinning solution is as follows: After diluting the spinning solution with DMAc, di-n-butylamine is added, and after stirring evenly, the solution is titrated with methanesulfonic acid solution to obtain the amino content.

[0082] Spandex breaking strength test method: The sample is placed under constant temperature and humidity conditions of 20℃±1℃ and 65%±5%, using a constant rate of elongation strength tester. A sample with an initial length of 50mm is pulled apart after sufficient balance, and the breaking strength is recorded.

[0083] Spandex yellowing resistance test method: (1) Sun method: Based on the phenomenon that white or light-colored products tend to turn yellow when exposed to natural sunlight for a long time, a sun lamp and a heating temperature control device are used to simulate a natural environment. The color change of the sample surface is observed within a specified time to determine the degree of discoloration of the sample, thereby determining the material's ability to resist yellowing under sunlight radiation. The test piece is exposed to light continuously at a temperature of (50±2)℃ for 8 hours. The chromaticity of the sample is detected by a spectrophotometer. The observation area of ​​the test sample is 0.390 inches. That is, the sample is placed 30mm from the center of the tray in the light-transmitting position of the spectrophotometer. The color difference between the sample and the blank sample is tested and evaluated. The sample color difference standard is based on the "Gray Sample Scale for Color Fastness Test of Textiles for Evaluation of Color Change" in GB / T 250-2008, and the corresponding yellowing level is obtained. (2) Ultraviolet method: Based on the phenomenon that white or light-colored products tend to turn yellow when exposed to ultraviolet light for a long time, the sample is irradiated with ultraviolet light. The color change of the sample surface is observed within a specified time to determine the degree of discoloration of the sample, thereby determining the material's ability to resist yellowing under ultraviolet radiation. The sample is placed on a tray with the irradiated surface of the sample facing the light source (D65 light source). The length of the sample is perpendicular to the length of the lamp tube. The irradiation time is 4 hours. The chromaticity of the sample is detected using a spectrophotometer. The observation area of ​​the test sample is 0.390 inches. That is, the sample is placed 30 mm from the center of the tray in the light transmission position of the spectrophotometer. The color difference between the sample and the blank sample is tested and evaluated. The color difference standard of the sample is based on the "Gray Sample Scale for Assessing Color Change in Textile Color Fastness Tests GB / T 250-2008", and the corresponding yellowing level is obtained. (3) Nitrogen oxide method: Test paper containing nitrophenol compounds provides nitrogen oxide groups to react with antioxidants in the fabric, accelerating the process of simulated fabric yellowing. The color change of the sample surface is observed within a specified time to determine the degree of discoloration of the sample, thereby determining the material's ability to resist nitrogen oxide yellowing. The test paper is folded in half along its length, and the spandex fiber is placed between the test papers. The test paper is placed in an oven at (50±2)℃ for 16 hours. The color of the sample is detected by a spectrophotometer. The observation area of ​​the test sample is 0.390 inches. The yellowed part of the sample is placed in the light-transmitting position of the spectrophotometer. The color difference between the sample and the blank sample is tested and evaluated. The color difference standard is based on the "GB / T 250-2008 Gray Scale Standard for Color Fastness Tests and Evaluation of Color Change in Textiles" to obtain the corresponding yellowing level.

Claims

1. A spandex with yellowing resistance, characterized in that The spandex contains a polyurethane-urea reaction product obtained from polyether polyol, polyisocyanate, and mixed amines, wherein the terminal amine content of the polyurethane-urea reaction product is less than 2 mmol / kg; the spandex also includes an anti-yellowing additive, wherein the main antioxidant in the anti-yellowing additive is one or more of a hydroxylamine antioxidant and a furanone antioxidant; the content of the anti-yellowing additive is 0.1-5%, calculated based on the mass of the spandex.

2. The spandex with yellowing resistance according to claim 1, characterized in that The main antioxidant specifically includes one or more of antioxidant 953, antioxidant Revonox 420, antioxidant Revonox 501, and antioxidant DBHA.

3. The spandex with yellowing resistance according to claim 1, characterized in that The polyether polyol includes one or more of polytetramethylene glycol polyol, polyethylene glycol polyol and polypropylene glycol polyol.

4. The spandex with yellowing resistance according to claim 1, characterized in that The polyisocyanate includes one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate.

5. The spandex with yellowing resistance according to claim 1, characterized in that The mixed amine includes a chain extender diamine and a capping agent monoamine, the diamine includes one or more of ethylenediamine, propylenediamine, butylenediamine, and pentamethylenediamine; the monoamine includes one or more of diethylamine, dipropylamine, and n-hexylamine; and the molar ratio of the diamine to the monoamine is 5:1 to 1:

1.

6. The spandex with yellowing resistance according to claim 2, characterized in that: The anti-yellowing additive further includes a secondary antioxidant, including a phosphate secondary antioxidant and / or a thioester secondary antioxidant, specifically including one or more of antioxidant 948, antioxidant 168, and antioxidant 412S.

7. The spandex with yellowing resistance according to claim 2, characterized in that: The anti-yellowing additive further includes an anti-nitrogen oxide agent; the anti-nitrogen oxide agent includes one or more of GA-80 and HN-130; the content of the anti-nitrogen oxide agent is 0.1-1.5% based on the mass of the spandex.

8. The spandex with yellowing resistance according to claim 2, characterized in that: The anti-yellowing additive further includes an anti-ultraviolet absorber, and the ultraviolet absorber includes one or more of salicylate ultraviolet absorbers, benzotriazole ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, triazine ultraviolet absorbers, and formamidine ultraviolet absorbers.

9. The spandex with yellowing resistance according to claim 8, characterized in that: The anti-ultraviolet absorber includes one or more of UV-3030, UV-903, UV-123, UV3853, UV-1, and UV-T; the content of the anti-ultraviolet absorber is 0.1-1.5% based on the mass of the spandex.

10. A method for preparing spandex with yellowing resistance according to claim 1, characterized in that: The method is obtained by dry spinning using the polyurethane-urea reaction product as a spinning solution; The spinning solution comprises a polyurethane-urea reaction product and a solvent, and the total terminal amine content of the spinning solution is 2 to 6 mmol / kg, calculated based on the solid content of the spinning solution; The preparation method is as follows: 1) Prepolymerizing polyisocyanate and polyether polyol in the presence of a solvent to prepare a polyurethane prepolymer solution; 2) reacting a polyurethane prepolymer solution with a mixed amine solution to obtain a stock solution containing a polyurethane-urea reaction product; 3) After the stock solution containing the polyurethane-urea reaction product is matured, the anti-yellowing additive is added to prepare a spinning solution, and spandex fibers with yellowing resistance are obtained through dry spinning technology.

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