CN114411283A

CN114411283A - Reactive dye easy-dyeing spandex and preparation method and dyeing method thereof

Info

Publication number: CN114411283A
Application number: CN202210111048.4A
Authority: CN
Inventors: 马立伟; 周莉; 张豪
Original assignee: ZHENGZHOU ZHONGYUAN SPANDEX ENGINEERING TECHNOLOGY CO LTD
Current assignee: ZHENGZHOU ZHONGYUAN SPANDEX ENGINEERING TECHNOLOGY CO LTD
Priority date: 2022-01-26
Filing date: 2022-01-26
Publication date: 2022-04-29
Anticipated expiration: 2042-01-26
Also published as: CN114411283B

Abstract

According to the invention, the branched chain with the electrophilic group is introduced into the main chain of the polyurethane polymer, and the group has stronger electron-withdrawing property in the subsequent dyeing process, can form a covalent bond with the reactive dye with the nucleophilic group, and fixes the reactive dye on the polyurethane fiber, so that the dyeing rate and the color fixing rate of the polyurethane fiber to the reactive dye are improved. The spandex is made into a skin-core structure, and the polyurethane of the core layer can be used for ensuring the fiber performance of the spandex. By adopting the dyeing method provided by the invention, the spandex fiber provided by the invention can obtain better dyeing effect by using the reactive dye with nucleophilic groups. The spandex, the core-spun yarn or the fabric prepared from the fiber provided by the invention can be dyed by reactive dye at one time, the operation is simple and convenient, the coloring is uniform, and the phenomenon that the dyeing of spandex-containing fabrics or fabrics is inconsistent is avoided.

Description

Reactive dye easy-dyeing spandex and preparation method and dyeing method thereof

Technical Field

The invention relates to reactive dye easy-dyeing spandex and a preparation method thereof, and a method for dyeing spandex-containing fabrics by using the reactive dye.

Background

The pure cotton fabric has the advantages of softness, good moisture absorption and air permeability and the like, and is a garment fabric commonly used in life. However, pure cotton fabric usually has no elasticity, and some garments requiring fabric elasticity, such as elastic jeans and the like, need to be blended with cotton yarn and spandex yarn to provide elasticity. Pure cotton fabrics are usually dyed using reactive dyes. The reactive dye has the characteristics of bright color, good leveling property, simple and convenient dyeing method, high dyeing fastness, complete chromatogram, lower cost and the like, and is mainly applied to dyeing and printing of fibers such as cotton, hemp, viscose, silk, wool and the like and blended fabrics thereof. Spandex fibers, because of their relaxed structure and low polarity, are usually dyed with disperse or acid dyes. Polyether and ester groups in the molecular structure of spandex are the main parts for dyeing disperse dyes, and amide groups in the crystalline region of spandex can also have hydrogen bond interaction with the dyes. The molecular structure of spandex does not have a molecular group which can be combined with reactive dyes, so that the reactive dyes are limited in the field of dyeing application of spandex fabrics.

As for the preparation method of reactive dye easy-dyeing spandex, few reports are reported in the prior patents, and the dyeing effect is basically improved by adding a dyeable component additive. For example, chinese patent document CN105442083A discloses adding a modifying assistant to a polyurethaneurea solution to perform quaternization modification on spandex fiber to improve the dye uptake, but only the ionic bond is performed with the water-soluble group of the reactive dye, so that the dyeing effect is improved to a limited extent; the Chinese patent document CN108138388A adopts the addition of alkaline earth metal salt additive in the stock solution, which can form covalent bond with the reactive dye to improve the dye uptake, and does not change the molecular structure of spandex. The methods provided by the above patent documents have limited improvement degree of dye uptake, no firmer covalent bond is formed between the active group of the reactive dye and the fiber molecule, and the dye is easy to fall off after washing or rubbing.

Compared with the prior art, the reactive dye easy-dyeing spandex fiber and the preparation technology thereof improve the covalent bond bonding capability of the molecular group of the spandex fiber and the reactive dye, so that the dye uptake and the fixation rate of the reactive dye are greatly enhanced.

Disclosure of Invention

The invention aims to provide spandex which is easy to dye by reactive dyes, and the invention also aims to provide a preparation method of the spandex which is easy to dye by the reactive dyes.

In the commonly used reactive dyes, there is a kind of reactive dye molecule having nucleophilic groups, which includes amino groups and hydroxyl groups on the original aromatic ring with weaker nucleophilicity in the dye molecule, or modified dyes with alkylamino groups and alkylhydroxyl groups introduced into the dye molecule. Therefore, the inventors thought that introducing electrophilic groups into the polyurethane polymer, so that the nucleophilic groups of the reactive dyes form covalent bonds with electrophilic groups in the polyurethane polymer during dyeing, can effectively improve the dyeability of the spandex to the reactive dyes.

Based on the principle, the scheme provided by the invention is as follows:

the reactive dye-dyeable spandex is characterized in that the reactive dye-dyeable spandex is of a skin-core structure, a skin layer is a reactive dye-dyeable polyurethane polymer, and a core layer is a conventional polyurethane polymer, wherein the reactive dye-dyeable polyurethane polymer comprises a branched chain with an electrophilic group.

Further, the electrophilic group is a vinyl group.

Further, in the reactive dye-dyeable polyurethane polymer, the mole percentage of the diol compound containing the branched chain with the electrophilic group in the whole alcohol raw material is 5-30%.

The electrophilic group adopted by the invention is a branched chain with vinyl introduced into a polyurethane polymer molecular chain, the vinyl on the branched chain has stronger electrophilicity, and can form covalent bond combination with the nucleophilic group of the reactive dye with the nucleophilic group, so that the reactive dye molecules are fixed on spandex fibers, and the dyeability of the spandex to the reactive dye is improved.

Since the vinyl group-branched diol compound generally has a lower molecular weight and thus lowers the average molecular weight of the soft segment, and the lower average molecular weight and branched structure of the diol compound adversely affect the tensile strength, modulus, etc. of the polyurethane polymer, the content of the vinyl group-containing diol in the skin structure is controlled. In the invention, in order to ensure the performance of the fiber made of the polyurethane polymer and simultaneously consider the number of vinyl groups capable of forming covalent bonds with reactive dyes on the branched chain, the mole percentage of the diol compound containing the vinyl groups in the whole alcohol raw material is selected to be 5-30%, preferably 5-15%, more preferably 10%, and is higher than the range, the physical performance of spandex is poorer, and if the mole percentage is lower than the range, the number of groups capable of being combined with the covalent bonds of the reactive dyes is too small, and the dyeing performance is insufficient. Wherein, the alcohol raw material is a raw material containing hydroxyl added in the stage of preparing the spinning solution.

Further, the skin layer area of the cross section of the reactive dye easy-dyeing spandex accounts for 5-50%, preferably 10% -30% of the whole cross section area.

The spandex easy to dye is in the cortex outside, and the physical characteristics of the spandex are ensured, so that the content of the cortex cannot be too large, and the content of the cortex cannot be too small for ensuring the dyeing effect.

Because the dyeability of the spandex fiber is the apparent performance of the fiber surface, in order to enable the prepared polyurethane fiber to have the best dyeability and simultaneously not reduce the fiber physical performance as much as possible, the inventor uses the polyurethane polymer with vinyl branched chains as the skin layer of the spandex fiber and uses the conventional polyurethane polymer as the core layer of the spandex fiber to prepare the polyurethane fiber with the skin-core structure. Therefore, the number of vinyl branched chains in the polyurethane polymer can be increased on the surface layer, the bonding capacity of the prepared spandex fiber surface layer and reactive dye is improved, the dyeability is improved, and meanwhile, the conventional polyurethane polymer is used on the spandex core layer to ensure the fiber mechanical property of the prepared spandex. Therefore, the sheath-core structure can give consideration to both the reactive dye dyeability and the fiber mechanical property of the spandex yarn, and the reactive dye dyeability of the spandex yarn is improved while the mechanical property of the spandex yarn is kept.

A preparation method of spandex which is easy to dye by reactive dye is characterized by comprising the following steps:

1) putting polyether diol or polyester diol, diol compound with electrophilic groups on side chains, micromolecular alcohols and diisocyanate into a polymerization kettle, reacting at the temperature of 90 ℃ under strong stirring to obtain a polymer, dissolving the obtained polyurethane polymer into a polar amide solvent, adding uniformly dispersed functional slurry, and uniformly mixing to finally obtain a 25-35% cortex spinning solution;

2) at least one of polyester diol of polyethylene glycol ester series, polytetrahydrofuran ether glycol, polycaprolactone glycol and polypropylene glycol is mixed with at least one of 4,4 '-diphenylmethane diisocyanate, 1, 5' -naphthalene diisocyanate, 1,4 '-cyclohexane diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate for reaction, wherein the molar ratio of diisocyanate to glycol is 1.6-2.1, after the reaction, the diisocyanate and the glycol are dissolved in an amide polar solvent, a chain extender and a terminator are added to prepare a polyurethane urea solution, and uniformly dispersed functional slurry is mixed with the functional slurry to finally obtain a polyurethane urea core layer spinning solution with the concentration of 35% -45%;

3) and (3) carrying out dry spinning by using a skin-core type composite spinning assembly to form the reactive dye easy-dyeing spandex with a skin-core structure, wherein the skin-layer spinning solution is used as a skin layer, and the core-layer spinning solution is used as a core layer.

Wherein, the sequence of the step 1) and the step 2) can be exchanged or carried out simultaneously.

The concentration of the cortex spinning solution prepared in the step 1) is lower than that of the core layer solution prepared in the step 2), because if the concentration of the cortex is higher, the solvent content of the cortex is relatively lower and can be quickly volatilized, so that a solid film is formed on the cortex, the volatilization of the core layer solvent is influenced, the solvent content of the cortex needs to be improved for ensuring the normal volatilization of the core layer solvent, and therefore, the concentration of the cortex is lower than the solid content of the core layer.

Further, the diol compound having an electrophilic group in a side chain in step 1) is preferably 2-vinylpropane-1.3 diol.

Further, the polyether glycol in the step 1) is polytetrahydrofuran ether glycol, and the molecular weight of the polyether glycol is preferably 1000-2000; the polyester dihydric alcohol is one or two of polybutylene glycol oxalate and polycarbonate dihydric alcohol, and the molecular weight of the polyester dihydric alcohol is preferably 1000-2000.

Further, the small molecule alcohols in the step 1) comprise dihydric alcohol and monohydric alcohol, and the dihydric alcohol is selected from one or more of ethylene glycol, 1, 4-butanediol, diethylene glycol, tripropylene glycol and ethylene diethylene glycol; the monohydric alcohol is selected from one or more of vinyl glycol ether and 4-hydroxybutyl vinyl ether.

The diol compounds in the small molecular alcohols have the function of chain extension, the monohydric alcohols have the function of termination, and the amine chain extender and the terminator can react with vinyl groups in the skin layer polyurethane polymer raw material to influence the molecular weight of the prepared polymer solution and the content of the vinyl groups, so that the preparation of the skin layer polyurethane solution containing vinyl needs to be chain extended by alcohols.

The vinyl glycol ether and the 4-hydroxybutyl vinyl ether are used as micromolecular alcohols, so that the vinyl content of the cortical polymer can be further improved, and the effect of further improving the dyeing effect of the product is achieved.

Preferably, the molar equivalent of the 2-vinyl propane-1.3 diol accounts for 10-30% of the molar equivalent of the total alcohol raw materials.

Further, the chain extender and the terminator of the core layer polyurethane polymer in the step 2) are at least two of ethylenediamine, propylenediamine, 1, 6-hexamethylenediamine, methyl dipropylamine, 1, 3-diamino-4-methylcyclohexane, diethylamine, cyclohexylamine, diisopropylamine, ethanolamine, diethanolamine, and N, N' -bis (2-hydroxypropyl) aniline.

Further, the functional slurry comprises: one or more of an anti-ultraviolet agent, an antioxidant, a lubricant, a chlorine-resistant agent and a delustering agent is ground by a grinding machine to achieve the purpose of uniform dispersion.

A method for dyeing reactive dye easy-dyeing polyurethane fiber is characterized by comprising the following steps:

1) degreasing the reactive dye easy-dyeing spandex fiber prepared by the method;

2) preparing a dye solution with the concentration of a reactive dye being 1% -3%, wherein the reactive dye is a reactive dye with nucleophilic groups, 10-30g of sodium sulfate or sodium chloride is added into each liter of the dye solution, and the pH value of the dye solution is adjusted to enable the solution to be in a range of 4.5-11;

3) weighing a spandex fiber sample, placing the spandex fiber sample in a dyeing cup, and adding a dye liquor according to a bath ratio of 1:10-1: 50;

4) dyeing, starting an infrared sample dyeing machine, heating to 40-50 ℃, putting into a dyeing cup, and keeping the temperature for 10-30 min. Then heating to 70-90 ℃, preserving heat for 20-50min, then cooling to normal temperature, and taking out a sample;

5) soaping, namely selecting soap powder or detergent, preparing soaping liquid with the concentration of 5-10g/L, soaping for 10-30min at the temperature of 70-90 ℃, and taking out a sample.

Wherein the purpose of soaping is to remove the surface flooding of the fibers.

Further, the deoiling treatment in the step 1) is to add a deoiling agent into hot water at the temperature of 80-90 ℃, soak spandex fibers and preserve heat for 10-30 min.

Because the polyurethane polymer easy to dye on the skin layer adopts alcohol chain extension, the obtained polyester polyurethane is easy to hydrolyze under the strong acid or strong alkali condition, so that the dyeing solution is kept to be weak acid or alkaline in the dyeing process, and the spandex fiber is dyed under the dyeing condition of the pH value of 4.5-11.

Furthermore, the nucleophilic group of the reactive dye is a nucleophilic group containing one or more of alkylamino, alkylhydroxy, aromatic ring with hydroxy and aromatic ring with amino.

Advantageous effects

Compared with the prior art, the electrophilic groups are introduced into the main chain of the polyurethane polymer, and the groups have stronger electron-withdrawing property in the subsequent dyeing process, can form covalent bonds with reactive dyes with nucleophilic groups, and fix the reactive dyes on polyurethane fibers, thereby improving the dyeing rate and the color fixing rate of the spandex to the reactive dyes. The spandex is made into a skin-core structure, and the polyurethane of the core layer can be used for ensuring the fiber performance of the spandex. By adopting the dyeing method provided by the invention, the spandex fiber provided by the invention can obtain better dyeing effect by using the reactive dye with nucleophilic groups.

The spandex, the core-spun yarn or the fabric prepared from the fiber provided by the invention can be dyed by reactive dye at one time, the operation is simple and convenient, the coloring is uniform, and the phenomenon that the dyeing of spandex-containing fabrics or fabrics is inconsistent is avoided.

Examples

Hereinafter, exemplary embodiments of the present invention will be described in detail, and the embodiments described below are exemplary and intended to explain the present invention and should not be construed as limiting the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. In the interest of clarity and conciseness, not all features of an actual implementation are described in the specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals.

Specifically, the invention provides reactive dye easy-dyeing spandex and a preparation method and a dyeing method thereof. The method comprises the following specific steps:

the reactive dye easy-dyeing spandex is characterized in that the reactive dye easy-dyeing spandex is of a skin-core structure, a skin layer is a reactive dye easy-dyeing polyurethane polymer, and a core layer is a conventional polyurethane polymer, wherein the reactive dye easy-dyeing polyurethane polymer comprises reactive dye easy-dyeing branched chains. The reactive dye-labile branch is not particularly limited in this regard, as long as the reactive dye-labile branch carries an electrophilic group that can react with a nucleophilic group in the reactive dye, and the reactive dye-labile branch can be a branch carrying an electrophilic group such as vinyl, nitrobenzene, aldonic group, carbonyl, or methylolacrylamide. The vinyl group can be added to spandex fiber by adding 2-vinyl propane-1.3 diol to the spandex raw material, and the method has simple process and low cost, so the electrophilic group is preferably the vinyl group in the invention. Wherein, in the reactive dye-dyeable polyurethane polymer, the molar percentage of the alcohol compound containing the reactive dye-dyeable branched chain in the whole alcohol raw material is 5-30%. The skin area of the cross section of the reactive dye easy-dyeing spandex is limited to be 5-50%, preferably 10% -30% of the whole cross section area.

The reactive dye easy-dyeing spandex is prepared by the following steps:

1) putting polyether diol or polyester diol, diol compound with a side chain containing vinyl, micromolecular alcohols and diisocyanate into a polymerization kettle, reacting at the temperature of 90 ℃ under strong stirring to obtain a polymer, dissolving the obtained polyurethane polymer into a polar amide solvent, adding uniformly dispersed multifunctional-containing slurry, and uniformly mixing to finally obtain a 25-35% cortex spinning solution;

according to the invention, the cortex spinning solution is prepared by adopting a bulk polymerization mode, and the main raw materials such as the diol compound, the vinyl-containing diol compound, the small molecular alcohol, the diisocyanate and the like are added at one time, and are dissolved in the solvent to obtain the spinning solution after the polymer is obtained by reaction, so that the reaction rate can be increased, the reaction steps can be saved, and the production efficiency of the spinning solution can be improved; as the amine chain extension can react with the groups of the reactive dye-easily-dyed branched chains to influence the components of the spinning solution, the invention adopts micromolecule alcohols as chain extension substances.

2) At least one of polyester diol of polyethylene glycol ester series, polytetrahydrofuran ether glycol, polycaprolactone glycol and polypropylene glycol is mixed with at least one of 4,4 '-diphenylmethane diisocyanate, 1, 5' -naphthalene diisocyanate, 1,4 '-cyclohexane diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate for reaction, wherein the molar ratio of diisocyanate to glycol is 1.6-2.1, after the reaction, the diisocyanate and the glycol are dissolved in an amide polar solvent, a chain extender and a terminator are added to prepare a polyurethane urea solution, and a slurry which is uniformly dispersed and contains multiple functions is mixed with the polyurethane urea solution to finally obtain a 35-45% polyurethane urea core layer spinning solution;

In the skin-core type composite spinning assembly, the ratio of the flow of the skin layer spinning solution to the flow of the core layer spinning solution is 0.05-1.

A dyeing method of reactive dye easy-dyeing polyurethane fiber comprises the following steps:

1) degreasing the easy-to-dye polyurethane fiber prepared by the method;

the presence of the fiber surface finish can cause difficult dye-uptake, so the fiber surface finish is generally removed by using a degreasing agent before dyeing.

the dye is usually dyed in light color, the dye concentration is about 1% -2%, and the dye is dyed in dark color, the dye concentration is higher, and is about 3%.

The sodium sulfate and the sodium chloride are neutral electrolytes and have the function of accelerating dyeing, so that the concentration difference of ions in the solution is ensured, and dye ions are promoted to approach fibers. The adsorption rate of the dye and the adsorption density of the fiber surface can be improved. The ionic strength of the solution can be effectively improved by increasing the concentration of the electrolyte, and the reaction of the dye and the fiber is accelerated. If the electrolyte concentration is too low, the color fixing effect cannot be achieved, if the electrolyte concentration is too high, the degree of dye aggregation and precipitation in the solution is easy to increase, the color fixing rate and efficiency of the dye are also reduced along with the increase of the electrolyte concentration, and the color fixing reaction is not favorable.

The pH of the solution has an effect on the solubility of the polyester spandex. The polyester spandex is easily dissolved under a low pH value, namely under a strong acidic condition and under a high pH value, namely under a strong basic condition, so that a weak acid or weak base or neutral environment is required.

3) Weighing a spandex fiber sample, and adding a dye solution according to a bath ratio of 1:10-1: 50;

the bath ratio refers to the mass ratio of the spandex fiber to the dye liquor. The bath ratio is related to the utilization rate of dye, leveling property, waste water amount and the like. Too large a bath ratio is beneficial to level dyeing, but the utilization rate of the dye is reduced, the dye is absorbed quantitatively by the fiber, and unabsorbed dye liquor is easy to waste. If the bath ratio is too low, the dye liquor quality is low, and the fibers cannot be completely dyed.

4) Dyeing, starting an infrared sample dyeing machine, heating to 40-50 ℃, putting into a dyeing cup, and keeping the temperature for 10-30 min. Then heating to 70-90 ℃, preserving heat for 20-50min, then cooling to normal temperature, and taking out a sample; after dyeing, a spectrophotometer can be used for measuring the absorbance of the dye liquor residual liquid and calculating the dyeing rate.

The dyeing step is divided into two sections for heat preservation, wherein the first section is the dyeing process, and the heat preservation time is the time for fully contacting the dyed fiber with the dye liquor. The second stage is the fixing process, and the temperature rise in the stage is the process of fully reacting the dye and the fiber.

5) Soaping, namely selecting soap powder or detergent, preparing soaping liquid with the concentration of 5-10g/L, soaping for 10-30min at the temperature of 70-90 ℃, and taking out a sample. After soaping, the absorbance of the soaping liquor can be measured by a spectrophotometer, and the color fixing rate is calculated.

The reason for soaping is to remove the loose color stained on the surface of the fiber, remove the unfixed dye and salt and ensure that the pH of the fabric is close to neutral.

The present invention will be described in more detail below with reference to examples.

Example 1

Firstly, preparing reactive dye easy-dyeing spandex, comprising the following steps:

step 1: preparation of reactive dye easy-dyeing spandex cortex spinning solution

1) Polytetramethylene ether glycol with the number average molecular weight of 2000, 4' -diphenylmethane diisocyanate, 2-vinyl propane-1.3 diol and ethylene glycol are mixed and stirred strongly, and react for 1h at the temperature of 90 ℃ to prepare the polymer. The NCO/OH molar ratio was 1, 2-vinylpropane-1.3 diol in 10 mol% of the diol content.

2) DMAC was added to the polymer and stirred for 30min to form a 30% strength solution.

3) Mixing 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -benzotriazole, triethylene glycol bis beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, magnesium stearate and titanium dioxide, adding the mixture into a DMAC solvent, stirring the mixture by a stirrer, and grinding the mixture by a grinder to achieve the purpose of uniform dispersion, wherein the mass percentage concentration of the prepared slurry is 30%;

4) and adding the slurry into a polymer solution to prepare a skin layer spinning solution, wherein the mass ratio of the slurry to the polymer solution is 1: 18.

Step 2: preparation of reactive dye easy-dyeing spandex core layer spinning solution

1) Polytetramethylene ether glycol (number average molecular weight 2000) and 4, 4' -diphenylmethane diisocyanate were reacted at 90 ℃ for 120min to prepare a prepolymer, in which the molar ratio NCO/OH was 1.7.

2) The prepared prepolymer was dissolved in N, N-dimethylacetamide to obtain a 40% concentration solution.

3) And (2) mixing ethylenediamine, pentamethylene diamine and diethylamine in a DMAC solvent to form a mixture with the concentration of 7%, uniformly mixing, adding the mixture into the prepolymer solution, and quickly stirring to prepare a polymer solution, wherein the molar ratio of amino group to isocyanic acid radical is 1.03.

4) Mixing 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -benzotriazole, triethylene glycol bis beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, magnesium stearate and titanium dioxide, adding the mixture into a DMAC solvent, stirring the mixture by a stirrer, and grinding the mixture by a grinder to achieve the purpose of uniform dispersion, wherein the mass percentage concentration of the prepared slurry is 40%;

5) and adding the slurry into a polymer solution to prepare a core layer spinning solution, wherein the mass ratio of the slurry to the polymer solution is 1: 16.

And step 3: preparation of reactive dye easy-dyeing spandex

And (3) carrying out dry spinning on the two spinning stock solutions through a skin-core type composite spinning assembly to obtain the reactive dye easy-dyeing spandex. In the spinning process, the ratio of the flow rates of the spinning solution of the skin layer to the core layer is 3: 7.

Through the steps, the reactive dye easy-dyeing spandex is prepared, the reactive dye easy-dyeing spandex is of a skin-core structure, the skin layer is reactive dye easy-dyeing polyurethane polymer containing vinyl branched chains, and the core layer is conventional polyurethane polymer. The area of the skin layer of the cross section of the spandex easy to dye of the reactive dye accounts for 36 percent of the area of the whole cross section.

Then, the prepared reactive dye easy-to-dye spandex is dyed by using the reactive dye, and the steps are as follows:

1) degreasing the easy-dyeing polyurethane fiber prepared by the method: adding a degreasing agent into hot water at the temperature of 80 ℃, then putting a spandex fiber sample, and soaking and preserving heat for 22 min;

2) preparing a dye solution with the concentration of a reactive dye being 2%, wherein the reactive dye is a reactive dye with nucleophilic groups, 25g of sodium sulfate is added into each liter of the dye solution, and the pH value of the dye solution is adjusted to be 7.5;

3) weighing 5g of spandex fiber sample, placing the spandex fiber sample in a dyeing cup, and adding a dye solution according to a bath ratio of 1: 20;

4) dyeing, starting the infrared sample dyeing machine, heating to 45 ℃, putting into a dyeing cup, and keeping the temperature for 25 min. Then heating to 80 ℃, preserving heat for 35min, then cooling to normal temperature, and taking out a sample;

5) and (4) soaping, namely selecting soap powder for washing, preparing soaping liquid with the concentration of 8g/L, soaping for 20min at the temperature of 80 ℃, and taking out a sample.

Example 2

1) Polytetramethylene ether glycol with the number average molecular weight of 2000, 4' -diphenylmethane diisocyanate, 2-vinyl propane-1.3 diol and ethylene glycol are mixed and stirred strongly, and react for 1h at the temperature of 90 ℃ to prepare the polymer. NCO/OH molar ratio was 0.95, 2-vinylpropane-1.3 diol accounted for 15% mol of diol content.

2) DMAC was added to the polymer and stirred for 30min to form a 35% strength solution.

3) Mixing 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -benzotriazole, triethylene glycol bis beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, magnesium stearate, and titanium dioxide, adding the mixture into a DMAC solvent, stirring the mixture by a stirrer, and grinding the mixture by a grinder to achieve the purpose of uniform dispersion, wherein the mass percentage concentration of the prepared slurry is 35%;

2) The prepared prepolymer was dissolved in N, N-dimethylacetamide to obtain a 35% concentration solution.

4) Mixing 2- (2' -hydroxy-3 ',5' -di-tert-butylphenyl) -benzotriazole, triethylene glycol bis beta- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, magnesium stearate, and titanium dioxide, adding the mixture into a DMAC solvent, stirring the mixture by a stirrer, and grinding the mixture by a grinder to achieve the purpose of uniform dispersion, wherein the mass percentage concentration of the prepared slurry is 35%;

And step 3: preparation of reactive dye easy-dyeing spandex

And (3) carrying out dry spinning on the two spinning stock solutions through a skin-core type composite spinning assembly to obtain the reactive dye easy-dyeing spandex.

In the spinning process, the ratio of the flow rates of the spinning solution of the skin layer to the core layer is 2: 8.

Through the steps, the reactive dye easy-dyeing spandex is prepared, the reactive dye easy-dyeing spandex is of a skin-core structure, the skin layer is reactive dye easy-dyeing polyurethane polymer containing vinyl branched chains, and the core layer is conventional polyurethane polymer. The area of the cortex of the cross section of the spandex easy to dye of the reactive dye accounts for 25% of the area of the whole cross section.

1) degreasing the easy-dyeing polyurethane fiber prepared by the method: adding a degreasing agent into hot water at 85 ℃, then putting a spandex fiber sample, and soaking and preserving heat for 25 min;

2) preparing a dye solution with the concentration of a reactive dye being 3%, wherein the reactive dye is a reactive dye with nucleophilic groups, 20g of sodium chloride is added into each liter of the dye solution, and the pH value of the dye solution is adjusted to be 7;

3) weighing 5g of spandex fiber sample, placing the spandex fiber sample in a dyeing cup, and adding a dye solution according to a bath ratio of 1: 25;

4) dyeing, starting an infrared sample dyeing machine, heating to 48 ℃, putting into a dyeing cup, and keeping the temperature for 22 min. Then heating to 85 ℃, preserving heat for 30min, then cooling to normal temperature, and taking out a sample;

5) and (4) soaping, namely selecting soap powder for washing, preparing a soaping liquid with the concentration of 7.5g/L, soaping for 25min at the temperature of 82 ℃, and taking out a sample.

The dyeing results of the two examples are shown in the table below, and the comparison shows that the dyeing rate and the color fastness of the reactive dye easy-dyeing spandex provided by the invention on the reactive dye are greatly improved compared with those of common spandex.

Examples	The dye uptake rate%	Color fixing rate%
			Example 1	≥80	≥80
Example 2	≥80	≥80
			Ordinary spandex	≥20	≥10

Claims

1. The reactive dye-dyeable spandex is characterized in that the reactive dye-dyeable spandex is of a skin-core structure, a skin layer is a reactive dye-dyeable polyurethane polymer, and a core layer is a conventional polyurethane polymer, wherein the reactive dye-dyeable polyurethane polymer comprises a branched chain with an electrophilic group.

2. The reactive dye-sensitized spandex according to claim 1, characterized in that said electrophilic groups are vinyl groups.

3. The reactive dye-dyeable polyurethane fiber according to claim 1, wherein the mole percentage of the alcohol compound containing a branch chain with an electrophilic group in the reactive dye-dyeable polyurethane polymer is 5-30% of the total alcohol raw material.

4. The reactive dye spandex of claim 1, wherein the sheath area of the cross-section of the reactive dye spandex is from 5 to 50% of the total cross-sectional area.

5. A process for the preparation of reactive dye-sensitized spandex according to any of claims 1 to 4, characterized in that it comprises the following steps:

2) at least one of polyester diol of polyethylene glycol ester series, polytetrahydrofuran ether glycol, polycaprolactone glycol and polypropylene glycol is mixed with at least one of 4,4 '-diphenylmethane diisocyanate, 1, 5' -naphthalene diisocyanate, 1,4 '-cyclohexane diisocyanate and 4, 4' -dicyclohexylmethane diisocyanate for reaction, wherein the molar ratio of diisocyanate to glycol is 1.6-2.1, after the reaction, the diisocyanate and the glycol are dissolved in an amide polar solvent, a chain extender and a terminator are added to prepare a polyurethane urea solution, and uniformly dispersed functional slurry is mixed with the polyurethane urea solution to finally obtain a polyurethane urea spinning solution with the concentration of 35-45 percent;

6. The method for preparing reactive dye-susceptible spandex according to claim 5, wherein the diol compound having an electrophilic group in a side chain in step 1) is preferably 2-vinyl propane-1.3 diol.

7. The method for preparing spandex with an easily dyeable reactive dye according to claim 6, wherein the molar equivalent of 2-vinyl propane-1.3 diol is 10% -30% of the molar equivalent of all the alcohol raw materials.

8. A process for dyeing spandex with reactive dye according to any of claims 1 to 4, characterized by comprising the following steps:

1) carrying out deoiling treatment on the reactive dye easy-dyeing spandex fiber;

4) dyeing, starting an infrared sample dyeing machine, heating to 40-50 ℃, putting into a dyeing cup, preserving heat for 10-30min, then heating to 70-90 ℃, preserving heat for 20-50min, then cooling to normal temperature, and taking out a sample;

9. The method for dyeing spandex easy to dye with reactive dye according to claim 8, wherein the nucleophilic group of the reactive dye is a nucleophilic group containing one or more of alkylamino, alkylhydroxy, aromatic ring with hydroxy and aromatic ring with amino.

10. Use of reactive dye dyeable spandex as claimed in any one of claims 1 to 4 for core-spun yarns, fabrics or garments.