CN117248298A - A kind of spandex with yellowing resistance and preparation method thereof - Google Patents

Abstract

The invention relates to polyurethane with yellowing resistance and a preparation method thereof, wherein the polyurethane contains polyurethane-urea reaction products obtained by polyether polyol, polyisocyanate and mixed amine, and the content of terminal amino groups of the polyurethane-urea reaction products is below 2 mmol/kg. The preparation method takes the polyurethane-urea reaction product as spinning solution and obtains the polyurethane-urea through dry spinning; the spinning solution comprises a polyurethane-urea reaction product and a solvent, wherein the total amine end group content of the spinning solution is 2-6 mmol/kg, calculated based on the solid content of the spinning solution; the product prepared by the method has excellent yellowing resistance, can solve the problem that the spandex fabric is deteriorated in the storage and use processes, and improves the service performance and service life of the spandex fabric.

Description

A kind of spandex with yellowing resistance and preparation method thereof

Technical field

The invention relates to spandex with yellowing resistance and a preparation method thereof, and belongs to the field of polyurethane elastic fibers. The spandex fiber prepared by the invention has excellent light stability, heat resistance, yellowing resistance, weather resistance, etc., which can prevent the fabric from deteriorating during storage and use, and improve the performance and service life of the spandex-containing fabric.

Background technique

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 and other substances during storage, sales, wearing, and cleaning processes, causing the performance of spandex fibers to deteriorate. Spandex molecules contain groups such as ether bonds, amide bonds, and urethane bonds. These groups will undergo chemical reactions such as photolysis, pyrolysis, and oxidation under the influence of light, heat, acid-base substances, and active chlorine, resulting in The molecular chain is damaged and cracked, and the reasons for yellowing are mainly as follows: (1) Yellowing caused by the spandex raw material itself: BHT is commonly contained in polymer polyols, polyisocyanates, small molecule amines and other raw materials (2, 6-di-tert-butyl-p-cresol), as well as reactive groups remaining in the fiber during the production process, which react chemically with nitrogen oxides in the air, resulting in yellowing. (2) Yellowing during packaging and storage: Packaging materials are polyethylene (or polystyrene) and other materials, which contain antioxidants (mainly BHT). Since BHT has very little solubility in polyethylene and is easy to volatilize , therefore, it will spread to the surface of the packaging material and form a yellow substance. (3) Yellowing during the weaving process, wearing and washing: Spandex is prone to yellowing due to exposure to sunlight, temperature changes, etc.

Over the years, many scientific researchers and corporate technical engineers have conducted a lot of research in this area. For example, to solve the problem of photoaging, one of the simplest methods is to solve the problem of photoaging through physical modification - adding light stabilizers or antioxidants. Patent CN105483856A discloses a method for preparing anti-UV aging spandex through in-situ polymerization. This method enables the anti-UV additive to be stably combined with spandex molecules in the form of chemical bonds. The results show that the UV-resistant spandex prepared by this method has more durable UV-resistant properties. Such technology can only improve certain aspects of spandex to a limited extent, but does not fundamentally solve the problem of anti-yellowing. Patent CN101736432A discloses a production method for yellowing-resistant polyurethane elastic fibers. During the prepolymerization process, isophorone diisocyanate equivalent to 0.5-10% of the total amount of isocyanate is added to reduce the amount of unsaturated double bonds in the polymer. A small amount of isophorone diisocyanate only has a certain improvement effect. The polymer will still turn yellow when exposed to ultraviolet rays and oxidation, and does not fundamentally solve the yellowing problem. Patent CN110685034A discloses a method for preparing spandex fiber that is resistant to phenol yellowing. The anti-phenol yellowing agent is connected through chemical bonds through an in-situ polymerization method. The phenol yellowing resistance does not decrease after multiple washings. This technology is indeed effective in solving the problem of durability. It is helpful, but it will destroy the molecular structure of spandex itself and have a certain impact on its mechanical properties.

All in all, there are many factors that affect the yellowing of spandex, which reduces the quality of spandex to a certain extent, especially the durability of the fiber. Under the condition that the performance of the polyurethane elastic fiber is basically unchanged, the invention can not only improve the color of the spandex fiber to be bright and white without turning yellow, but also fundamentally solve the problem of yellowing of the polyurethane elastic fiber during weaving and wearing.

Contents of the invention

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

Technical solution: The present invention provides a spandex with yellowing resistance. The spandex contains a polyurethane-urea reaction product obtained from a polyether polyol, a polyisocyanate, and a mixed amine. The polyurethane-urea reaction product has a terminal amine group content of Below 2mmol/kg.

The spandex also includes an anti-yellowing auxiliary, and the main antioxidant in the anti-yellowing auxiliary includes more than one of hydroxylamine antioxidants, tertiary amine antioxidants, and furanone antioxidants; The anti-yellowing additive content is 0.1 to 5%, calculated based on the quality of spandex;

Preferably, the main antioxidant specifically includes one or more of antioxidant 953, antioxidant Revonox420, antioxidant Revonox501, antioxidant Revonox 501, antioxidant DBHA and antioxidant 264.

The polyether polyol includes at least one of polytetrahydrofuran ether polyol, polyethylene glycol polyol, and polypropylene glycol polyol.

The polyisocyanates include diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and/or derivatives and/or modified polymers More than one kind.

The mixed amine includes a chain extender diamine and an end-capping agent monoamine, and the diamine includes at least one of ethylenediamine, propylenediamine, butanediamine, and pentanediamine; the monoamine Including one or more of diethylamine, dipropylamine, and n-hexylamine; the molar ratio of the diamine to the monoamine is 5:1 to 1:1.

The anti-yellowing auxiliary also includes auxiliary antioxidants, including phosphate ester auxiliary antioxidants and/or thioester auxiliary antioxidants, specifically including antioxidant 948, antioxidant 168, antioxidant More than one of 412S.

The anti-yellowing auxiliary also includes an anti-nitrogen oxide agent; the anti-nitrogen oxide agent includes more than one of GA-80 and HN-130; the content of the anti-nitrogen oxide agent is based on the The spandex mass is calculated as 0.1~1.5%.

The anti-yellowing auxiliary also includes anti-UV absorbers, and the UV absorbers include salicylate UV absorbers, benzotriazole UV absorbers, substituted acrylonitrile UV absorbers, triazines One or more of UV absorbers and formamidine UV absorbers.

Preferably, the anti-UV absorber includes at least one of UV-3030, UV-903, UV-123, UV3853, UV-1, and UV-T; the content of the anti-UV absorber is based on the quality of spandex. Calculated as 0.1~1.5%.

The preparation method of spandex with yellowing resistance of the present invention is obtained by dry spinning by using the polyurethane-urea reaction product as a spinning solution;

The spinning liquid includes a polyurethane-urea reaction product and a solvent, and the total terminal amine content of the spinning liquid is 2 to 6 mmol/kg, calculated based on the solid content of the spinning liquid;

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) React the polyurethane prepolymer solution with the mixed amine solution to prepare a stock solution containing the polyurethane-urea reaction product;

3) After aging the stock solution containing the polyurethane-urea reaction product, use the aged polyurethane-urea stock solution as the spinning liquid to obtain spandex fiber with yellowing resistance through dry spinning technology.

Beneficial effects: The spandex with yellowing resistance of the present invention has excellent resistance to nitrogen and oxygen yellowing by controlling the terminal amine group content of the polyurethane-urea reaction product. In addition, by compounding with a specific anti-yellowing agent, the spandex can further The spandex's resistance to nitrogen-oxygen yellowing and light-yellowing is improved, and the color of the fiber is bright and white. This ensures that the spandex fiber of the present invention will not turn yellow when used for a long time without deteriorating its mechanical properties, and its yellowing resistance is much higher than that of similar products.

Detailed ways

The invention provides a spandex with yellowing resistance, which contains a polyurethane-urea reaction product obtained by polyether polyol, polyisocyanate and mixed amine. The terminal amine group content of the polyurethane-urea reaction product is between 0 and 2 mmol/kg. ;

Further, the spandex with yellowing resistance contains polyurethane prepolymer obtained by the reaction of polyether polyol, polyisocyanate and polyurethane-urea reaction product obtained by mixed amine;

The mixed amine includes a chain extender diamine and an end-capping agent monoamine. The diamine includes at least one of ethylenediamine, propylenediamine, butanediamine, and pentanediamine. The monoamine Including one or more of diethylamine, dipropylamine and n-hexylamine;

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

The polyether polyol includes at least one of polytetrahydrofuran ether polyol, polyethylene glycol polyol, and polypropylene glycol polyol;

The polyisocyanates include diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and/or derivatives and/or modified polymers more than one kind;

The spandex with yellowing resistance contains 0.1 to 5% of anti-yellowing additives, preferably 0.5 to 3% of anti-yellowing additives, calculated based on the quality of the spandex;

Further, the anti-yellowing auxiliary includes a main antioxidant, and the main antioxidant includes more than one of hydroxylamine antioxidants, tertiary amine antioxidants, and furanone antioxidants;

Preferably, the antioxidant includes at least one of antioxidant 953, antioxidant Revonox420, antioxidant Revonox501, antioxidant DBHA and antioxidant 264;

Further, the antioxidants also include phosphate ester auxiliary antioxidants and/or thioester auxiliary antioxidants, including more than one of antioxidant 948, antioxidant 168, and antioxidant 412S. ;

In some examples of the present invention, the main antioxidant does not use hindered phenolic antioxidants or primary amine antioxidants alone;

Preferably, the antioxidant content is 0.1 to 3%, calculated based on the mass of spandex;

Further, the anti-yellowing auxiliary agent 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 to 1.5%, calculated based on the mass of spandex.

Furthermore, the anti-yellowing additives include anti-UV absorbers, and the UV absorbers include salicylate UV absorbers, benzotriazole UV absorbers, and substituted acrylonitrile UV absorbers. , one or more of triazine UV absorbers and formamidine UV absorbers;

In some examples of the present invention, the ultraviolet absorbers include at least one of salicylate ultraviolet absorbers, substituted acrylonitrile ultraviolet absorbers, triazine ultraviolet absorbers, and formamidine ultraviolet absorbers. ;

Preferably, the anti-UV absorber includes at least one of UV-3030, UV-903, UV-123, UV-3853, UV-1, and UV-T;

The content of the anti-UV absorber is 0.1 to 1.5%, calculated based on the mass of spandex.

Optionally, the yellowing resistant spandex is added with titanium dioxide and/or fluorescent whitening agent to improve the color of the spandex fiber;

The fluorescent whitening agent includes triazine amino stilbene type fluorescent whitening agent;

The titanium dioxide content is 0.1% to 1%, calculated based on the quality of spandex;

The content of the fluorescent whitening agent is 10 ppm to 10,000 ppm, calculated based on the quality of spandex.

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

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

The solvent includes at least one of N,N-dimethylacetamide DMAc, N-methyl-2-pyrrolidone NMP, and dimethylformamide DMF;

The mass concentration of the spinning liquid is 30%wt～40%wt;

The viscosity of the spinning liquid is 3000-12000 poise.

In some examples of the present invention, the preparation method of spandex with yellowing resistance includes:

1) Prepolymerizing polyisocyanate and polyether polyol in the presence of a solvent to prepare a polyurethane prepolymer solution;

2) React the polyurethane prepolymer solution with the mixed amine solution to prepare a stock solution containing the polyurethane-urea reaction product;

3) After aging the stock solution containing the polyurethane-urea reaction product, use the aged polyurethane-urea stock solution as the spinning liquid to obtain spandex fiber with yellowing resistance through dry spinning technology.

The dry spinning technology includes the steps of jetting, drawing, drying, false twisting, and winding into filament;

Preferably, spandex oil can be coated on the spandex surface after the false twisting step. The spandex oil includes hydrophilic silicone oil, such as polyether-modified polysiloxane and amino-modified polysiloxane.

The mass concentration of the spinning liquid is 30%wt～40%wt;

The viscosity of the spinning liquid is 3000-12000 poise;

The total amine content of the spinning solution is between 2 and 6 mmol/kg. Controlling the total amine content of the spinning solution in a lower range can reduce the reaction between active groups and nitrogen oxides and avoid yellowing.

The molar ratio of diamine to monoamine in the mixed amine is 5:1 to 1:1, which can adjust the viscosity of the spinning solution in a suitable range to improve the spinning effect of spandex, and also improve the yellowing resistance of spandex.

The NCO content of the polyurethane prepolymer is 2.5 to 3.5 wt%.

Further, in some examples of the present invention, the anti-yellowing auxiliary agent, optional titanium dioxide, and optional fluorescent whitening agent are added in step 3);

As an example, the anti-yellowing additive, optional titanium dioxide, and optional fluorescent whitening agent can be dispersed in a solvent and added in step 3).

Furthermore, the spandex can also be added with other common functional additives in this field, as long as the performance of the product is not degraded. Such as one or more of lubricants, matting agents, dyeing auxiliaries, and chlorine-resistant auxiliaries.

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

Example

The preparation method of spandex with yellowing resistance includes:

1) Prepolymerize diphenylmethane diisocyanate and polytetrahydrofuran ether polyol in the presence of DMAc to prepare a polyurethane prepolymer solution;

2) React the polyurethane prepolymer solution with the mixed amine solution to prepare a stock solution containing the polyurethane-urea reaction product;

3) After aging the stock solution containing the polyurethane-urea reaction product, add an optional anti-yellowing auxiliary, and use the matured polyurethane-urea stock solution as the spinning liquid to obtain a yarn with yellowing resistance through dry spinning technology. Performance spandex fiber, the denier of spandex fiber is 44dtex.

For details of the examples and comparative examples, please see Table 1, Table 2, and Table 3 below:

Table 1:

Table 2:

table 3:

Among them, the test method for the terminal amine group of the polyurethane-urea reaction product: coat the original solution containing the polyurethane-urea reaction product and put it into an oven to dry, so that the free small molecule amine and the solvent DMAc are completely volatilized, and then the dried Dissolve the film in DMAc, add di-n-butylamine, stir evenly, and titrate with methanesulfonic acid solution to obtain the amine content.

Test method for the total amine content of the spinning solution: dilute the spinning solution with DMAc, add di-n-butylamine, stir evenly, and titrate with methane sulfonic acid solution to obtain the amine content.

Test method for the breaking strength of spandex: The sample is subjected to constant temperature and humidity conditions of 20℃±1℃ and humidity of 65%±5%, using a constant velocity elongation strength machine, using a sample with a starting length of 50mm. After sufficient balance, pull it off and record the breaking strength.

Spandex yellowing resistance test method: (1) Solar method: According to the phenomenon that white or light-colored products are prone to yellowing under long-term exposure to natural sunlight, a solar lamp and heating temperature control device are used to simulate the natural environment. Observe the color changes on the surface of the sample within a specified period of time to determine the degree of discoloration of the sample, thereby determining the material's ability to resist yellowing under solar radiation. Let the test piece be exposed to light continuously at a temperature of (50±2)℃ for 8 hours. Use a spectrophotometer to detect the chromaticity of the sample. The observation area of the test sample is 0.390 inches. That is, place the sample 30mm close to the center side of the tray at the light-transmitting position of the spectrophotometer. Test and evaluate the color of the sample and the blank sample. Color difference value. The color difference standard of the sample is based on "GB/T 250-2008 Gray Sample Card for Evaluating Discoloration in Textile Color Fastness Tests", and the corresponding yellowing progression is obtained. (2) Ultraviolet method: According to 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 rays, and the change in color of the surface of the sample is observed within a specified time to determine the quality of the sample. The degree of discoloration is used to determine the material's ability to resist yellowing under ultraviolet radiation. Place the sample on the tray, with the illuminated surface of the sample facing the light source (D65 light source). The length direction of the sample is perpendicular to the length direction of the lamp tube. The irradiation time is 4 hours. Use a spectrophotometer to detect the chromaticity of the sample. The observation area of the test sample is 0.390 inches. That is, place the sample 30mm close to the center side of the tray at the light-transmitting position of the spectrophotometer. Test and evaluate the color of the sample and the blank sample. Color difference value. The color difference standard of the sample is based on "GB/T 250-2008 Gray Sample Card for Evaluating Discoloration in Textile Color Fastness Tests", and the corresponding yellowing progression is obtained. (3) Nitrogen-oxygen method: Use test paper containing nitrophenolic compounds to provide nitrogen-oxygen groups to react with the antioxidants in the fabric to accelerate the process of simulating the yellowing of the fabric, and observe the changes in the color of the sample surface within a specified time. , determine the degree of discoloration of the sample, and thereby determine the material's ability to resist nitrogen and oxygen yellowing. Fold the test paper in half along its length, place the spandex fiber between the test papers, and place it in an oven at (50±2)°C for 16 hours. Use a spectrophotometer to detect the color of the sample. The observation area of the test sample is 0.390 inches. That is, place the yellowed part of the sample in the light-transmitting position of the spectrophotometer, and test and evaluate the color difference between the sample and the blank sample. The color difference standard is based on the "GB/T 250-2008 Gray Card Standard for Evaluating Discoloration in Textile Color Fastness Tests", and the corresponding yellowing progression is obtained.

Claims (10)

1. The polyurethane-urea reaction product is characterized in that the polyurethane-urea reaction product is obtained by polyether polyol, polyisocyanate and mixed amine, and the amine end group content of the polyurethane-urea reaction product is below 2 mmol/kg.

2. The spandex with yellowing resistance according to claim 1, wherein the spandex further comprises an anti-yellowing auxiliary agent, wherein the main antioxidant in the anti-yellowing auxiliary agent comprises more than one of hydroxylamine antioxidants, tertiary amine antioxidants and furanone antioxidants; the content of the anti-yellowing auxiliary agent is 0.1-5%, calculated based on the mass of spandex; the main antioxidants specifically comprise more than one of antioxidant 953, antioxidant Revonox420, antioxidant Revonox501, antioxidant DBHA and antioxidant 264.

3. The spandex of claim 1 wherein the polyether polyol comprises at least one of polytetrahydrofuran ether polyol, polyethylene glycol polyol, polypropylene glycol polyol.

4. The spandex of claim 1 wherein the polyisocyanate comprises one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and/or derivatives and/or modified polymers.

5. The spandex with yellowing resistance according to claim 1, wherein the mixed amine comprises chain extender diamine and end capping agent monoamine, and the diamine comprises more than one of ethylenediamine, propylenediamine, butylenediamine and pentylene diamine; the monoamine comprises more than one of diethylamine, dipropylamine and n-hexylamine; the molar ratio of diamine to monoamine is 5:1-1:1.

6. The spandex with yellowing resistance according to claim 2, wherein the anti-yellowing auxiliary agent further comprises an auxiliary antioxidant, wherein the auxiliary antioxidant comprises more than one of phosphate auxiliary antioxidants and/or thioester auxiliary antioxidants, and the auxiliary antioxidant specifically comprises an antioxidant 948, an antioxidant 168 and an antioxidant 412S.

7. The spandex having a yellowing resistance according to claim 2, wherein the anti-yellowing auxiliary further comprises an anti-nitrogen oxide agent; the anti-nitrogen oxide agent comprises more than one of GA-80 and HN-130; the content of the anti-nitrogen oxide agent is calculated to be 0.1-1.5% based on the mass of the spandex.

8. The spandex with yellowing resistance according to claim 2, wherein the anti-yellowing auxiliary further comprises an anti-ultraviolet absorber, and the ultraviolet absorber comprises more than one of salicylate ultraviolet absorber, benzotriazole ultraviolet absorber, substituted acrylonitrile ultraviolet absorber, triazine ultraviolet absorber and formamidine ultraviolet absorber.

9. The spandex having anti-yellowing property according to claim 8, wherein the anti-ultraviolet absorber comprises one or more of UV-3030, UV-903, UV-123, UV3853, UV-1, UV-T; the content of the ultraviolet resistant absorbent is calculated to be 0.1-1.5% based on the mass of the spandex.

10. A method for preparing spandex with yellowing resistance according to claim 1, wherein the polyurethane-urea reaction product is obtained by dry spinning with a spinning solution;

the spinning solution comprises a polyurethane-urea reaction product and a solvent, wherein the total amine end group content of the spinning solution is 2-6 mmol/kg, calculated based on the solid content of the spinning solution;

the preparation method comprises the following steps:

1) Carrying out prepolymerization reaction on polyisocyanate and polyether polyol in the presence of a solvent to prepare polyurethane prepolymer solution;

2) Reacting the polyurethane prepolymer solution with a mixed amine solution to obtain a stock solution containing a polyurethane-urea reaction product;

3) And (3) curing the stock solution containing the polyurethane-urea reaction product, and taking the cured polyurethane-urea stock solution as spinning solution to obtain the polyurethane fiber with yellowing resistance through a dry spinning technology.