Dyeing aid and easy-to-dye polyurethane urea elastic fiber containing dyeing aid

Abstract

The invention relates to a dyeing auxiliary agent and a dyeable polyurethane urea elastic fiber containing the dyeing auxiliary agent. Copolymerized polyamide comprises a reaction product of at least one aliphatic acid and at least one micromolecular amine; the elastic fiber contains 1.0%-5.0% of the dyeing auxiliary agent based on the total mass of the easy-to-dye polyurethane urea elastic fiber; the elastic fiber also contains a color fixing agent and / or a whitening agent; polyurethane-urea, a dyeing aid, an optional color fixing agent and an optional whitening agent are used as spinning raw materials, and the easy-to-dye polyurethane-urea elastic fiber containing the dyeing aid is obtained through dry spinning in the presence of a solvent. The auxiliary has good dissolving and dispersing capacity in a polyurethane-urea spinning solution, and has high amine value, hydroxyl value and transparent chromaticity, so that the dyeing auxiliary has good dyeing performance and color fastness while keeping the existing appearance and physical properties of spandex fibers after being added into spandex.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and particularly relates to a dyeing assistant, and also relates to a dyeable polyurethane-urea elastic fiber containing the dyeing assistant. Technical Background

[0002] Polyurethane-urea elastic (spandex) fiber, as an elastic fiber, has been widely used in the textile industry due to its excellent tensile and elastic recovery properties. It is often blended with fibers such as polyester, nylon, and cotton to endow fabrics with better elasticity, comfort, and durability. However, with the improvement of the national consumption level, people have put forward higher requirements for the performance of spandex blended fabrics. At present, the dyeing of spandex blended fabrics is widely used, but its dyeing performance is greatly affected by the types of blended fibers. When blended with polyester, since both have good lipophilicity, using disperse dyes for dyeing can easily obtain good dyeing effects. However, nylon and cotton fibers have strong hydrophilicity and are usually dyed with acid or reactive dyes. At this time, due to the dense polymer structure of spandex and the presence of a large number of soft segments with relatively weak polarity, the binding force with dyes is weak, resulting in difficult coloring of spandex fibers. As a result, cotton-spandex and nylon-spandex blended fabrics often have problems such as non-dyeing of spandex, easy appearance of "white spots", and poor wash fastness and color fastness of clothes, which limit the further development of blended spandex fabrics in the mid- to high-end fields.

[0003] Therefore, improving the dye uptake rate and color fastness of spandex in different types of blended fabrics is a major problem faced by technical personnel in the textile field at present. Currently, to improve the dyeing effect of spandex fibers, the dye uptake rate of spandex can be increased by adding a dyeing assistant. For example, CN105420843A improves the dyeability and dyeing color fastness of polyurethane elastic fibers by adding a dialkyldimethylammonium salt assistant as a dyeing assistant, but the price of quaternary ammonium salt products is generally relatively high, and the dyeing effect on dark dyes (such as acid black, acid dark blue, etc.) is poor. CN112410925A improves its dyeability by adding ground nylon 6 and nylon 610 as dyeing assistants into the spandex spinning solution; CN112410930A adds a solid polyamide resin modified with a mixture of a silane coupling agent and a polyethylene-olefin copolymer grafted maleic anhydride polymer to achieve excellent dyeing performance of polyurethane elastic fibers;

[0004] CN107641847A improves the dyeing performance of spandex by adding liquid polyamides such as epoxy resin curing agents; the following problems generally exist in these common dyeing assistants for polyamide resins: ① It is only soluble in some strongly polar solvents and has poor solubility in the commonly used solvents for spandex. The uneven solution affects the spinnability of spandex; ② The amine end group content is small. When the addition amount is low, the improvement of dyeing performance is not obvious. When the addition amount is high, it affects the physical properties of the fiber; ③ The hydroxyl group content is small, and the binding ability with reactive dyes is weak, and it cannot improve the dyeing ability under the dyeing conditions of spandex, neutral, reactive, etc.; ④ The color is opaque and the yellow color is relatively deep. After adding, it is easy to affect the appearance chromaticity of spandex products, and the dyeing of the corresponding color system in the subsequent process is restricted to a certain extent. Summary of the Invention

[0005] Technical Problem: Aiming at the deficiencies of the prior art, the present invention provides a dyeing assistant, which has good dissolution and dispersion ability in polyurethane-urea spinning solution, and has a high amine value, hydroxyl value and relatively transparent chromaticity, so that when the dyeing assistant is added to spandex, while maintaining the existing appearance and physical properties of spandex fibers, it has good dyeing performance and color fastness.

[0006] Technical Solution: The present invention provides a dyeing assistant, including modified copolyamide, wherein the copolyamide includes the reaction product of at least one aliphatic acid and at least one small molecule amine;

[0007] The aliphatic acid includes aliphatic polybasic acids with 12 to 36 carbon atoms. Further, it includes one or more of dodecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, docosanedioic acid, dimer fatty acid, and dimer linoleic acid.

[0008] The small molecule amine includes polyamines with 2 to 12 carbon atoms. Further, it includes one or more of ethylenediamine, propylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dihexenetriamine, dibutenetriamine, and triethylenetetramine.

[0009] The number average molecular weight of the copolyamide is 500 to 5000 g / mol; the acid value of the copolyamide is below 1 mg KOH / g, and the amine value is 20 to 40 mg KOH / g; the chromaticity of the copolyamide, that is, the iron-cobalt color number, is 4 to 6.

[0010] The modified copolyamide is hydroxyl modified, and the hydroxyl modified copolyamide is obtained by reacting the copolyamide resin with an aqueous aldehyde solution in the presence of an acid catalyst.

[0011] The aldehydes described above include one or more of formaldehyde, acetaldehyde, and propionaldehyde; the acid catalysts described above include one or more of formic acid, sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid; the hydroxyl value of the hydroxyl-modified copolyamide is 10 to 30 mg KOH / g.

[0012] The easily dyeable polyurethane-urea elastic fiber containing the above dyeing assistant contains 1.0% to 5.0% of the above dyeing assistant based on the total mass of the easily dyeable polyurethane-urea elastic fiber.

[0013] The elastic fiber described above also contains a fixing agent and / or a brightening agent. The mass content of the fixing agent is 0.2% to 1.0%, calculated based on the total mass of the easily dyeable polyurethane-urea elastic fiber; the mass content of the brightening agent is 0.05% to 0.20%, calculated based on the total mass of the easily dyeable polyurethane-urea elastic fiber.

[0014] The fixing agents described above include one or more of cetylpyridinium chloride, cetylpyridinium bromide, the condensate of dimethylamine and epichlorohydrin, the condensate of diethanolamine polyether and epichlorohydrin, and ethyl dimethylaminoethyl methacrylate quaternary salt; the brightening agents described above include one or more of polydimethylsiloxane, sodium diphenylstyrylbiphenyl disulfonate, 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, solvent blue 45, and phthalocyanine blue.

[0015] The preparation method of the easily dyeable polyurethane-urea elastic fiber of the present invention is as follows:

[0016] Using polyurethane-urea, a dyeing assistant, an optional fixing agent, and an optional brightening agent as spinning raw materials, and obtaining them by dry spinning in the presence of a solvent;

[0017] Among them, the polyurethane-urea is the reaction product of a polymer polyol, a polyisocyanate, a diamine chain extender, and a terminator;

[0018] The polymer polyol includes a polyester polyol and / or a polyether polyol. The polymer polyol includes a polyether polyol, and the polyether polyol includes one or more of polytetrahydrofuran diol, polyethylene glycol, or polypropylene glycol;

[0019] The number average molecular weight of the polymer polyol is 1000 to 2000 g / mol;

[0020] The polyisocyanates include one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dimethylbiphenyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dicyclohexylmethane diisocyanate, and / or derivatives and / or modified polymers;

[0021] The diamine chain extender described above includes one or more of ethylenediamine, propanediamine, 2-methyl-1,5-pentanediamine, pentanediamine, and hexanediamine;

[0022] The terminator includes one or more of dimethylamine, diethylamine, dipropylamine, n-butanol, and ethanolamine.

[0023] The solvent described above includes one or more of N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide.

[0024] Beneficial effects: The present invention prepares a dyeing assistant, which has good dissolution and dispersion ability in the polyurethane-urea spinning solution, and has a relatively high amine value, hydroxyl value, and relatively transparent chromaticity. The spandex fiber products added with this assistant have good dyeing performance and color fastness while maintaining the existing appearance and physical properties. Specific embodiments

[0025] A dyeing assistant of the present invention includes a modified copolyamide, wherein the copolyamide includes a reaction product of at least one aliphatic acid and at least one small molecule amine;

[0026] The aliphatic acid includes aliphatic polybasic acids with 12 to 36 carbon atoms, and further includes one or more of dodecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, docosanedioic acid, dimer fatty acid, and dimer linoleic acid;

[0027] In some examples of the present invention, the aliphatic acid includes one or more of dodecanedioic acid, octadecanedioic acid, and dimer linoleic acid;

[0028] The small molecule amine includes polyamines with 2 to 12 carbon atoms, and further includes one or more of ethylenediamine, propanediamine,, pentanediamine, hexanediamine, diethylenetriamine, dipropylenetriamine, dihexylenetriamine, dibutylenetriamine, and triethylenetetramine;

[0029] In some examples of the present invention, the small molecule amine includes one or more of ethylenediamine, propanediamine, diethylenetriamine, and dihexylenetriamine;

[0030] The number average molecular weight of the copolyamide is 500 to 5000 g / mol;

[0031] In the present invention, the molecular weight is obtained by testing with a gel permeation chromatograph GPC;

[0032] The acid value of the copolyamide is less than 1 mg KOH / g, and the amine value is 20 to 40 mg KOH / g;

[0033] Preferably, the chromaticity (iron-cobalt color number) of the copolyamide is 4 to 6;

[0034] In the present invention, the acid value is calibrated by dissolving the copolyamide in N,N-dimethylformamide and titrating with a standard potassium hydroxide solution until the color of the phenolphthalein indicator changes to mark the titration end point; the acid value is calculated based on the volume and concentration of the consumed standard potassium hydroxide solution and the mass of the sample.

[0035] In some examples of the present invention, by controlling the molar amount of the polyamine to be higher than that of the aliphatic polyacid, the prepared copolyamide is controlled to be amine-terminated and substantially free of carboxylic acid end groups.

[0036] In the present invention, the amine value is calculated by dissolving the copolyamide in glacial acetic acid and titrating the sample solution with a standard perchloric acid solution until a significant change in the color of the indicator occurs; the amine value is calculated based on the volume and concentration of the consumed standard perchloric acid solution and the mass of the sample.

[0037] In the present invention, the chromaticity (iron-cobalt color number) is obtained by grinding the sample into a powder and then pressing it into a sheet to obtain a uniform surface; under a D65 standard light source, the sample is compared with an iron-cobalt color card, and the closest color card is selected as the iron-cobalt color number of the sample.

[0038] The modified copolyamide is modified with hydroxyl groups, and the hydroxyl-modified copolyamide is obtained by reacting an aqueous aldehyde solution with a copolyamide resin in the presence of an acid catalyst to obtain a hydroxyl-modified copolyamide;

[0039] The aldehyde substances include one or more of formaldehyde, acetaldehyde, and propionaldehyde;

[0040] The acid catalysts include one or more of formic acid, sulfuric acid, hydrochloric acid, and p-toluenesulfonic acid;

[0041] The hydroxyl value of the hydroxyl-modified copolyamide is 10 to 30 mg KOH / g;

[0042] In the present invention, the hydroxyl value is obtained by mixing the hydroxyl-modified copolyamide with acetic anhydride and pyridine and reacting for a period of time to completely acetylate the hydroxyl groups; after the reaction is completed, water is added to decompose the excess acetic anhydride to generate acetic acid; the generated acetic acid is titrated with a standard potassium hydroxide solution, and the phenolphthalein indicator is used to indicate the titration end point; the hydroxyl value is calculated based on the volume and concentration of the consumed standard potassium hydroxide solution and the mass of the sample.

[0043] As an example, the specific preparation method of the hydroxyl-modified copolyamide is as follows:

[0044] React the copolyamide with an aqueous formaldehyde solution, using formic acid as a catalyst, and after removing the unreacted substances by precipitation, vacuum drying to obtain a hydroxylated modified copolyamide resin;

[0045] In the present invention, the hydroxylated modified copolyamide resin contains a relatively low crystalline region and has poor crystallinity regularity. Compared with conventional polyamide materials such as nylon 66, nylon 6, and nylon 610, it has better compatibility with the polyurethane-urea system. During the subsequent dyeing process, dyes can more easily penetrate into the amorphous region. The hydroxylated modified copolyamide resin also contains a large number of amino and hydroxyl groups, which can further improve the hydrophilicity of the polyamide and has a better dyeing and fixing effect on various dyes such as acidic and reactive dyes, thereby improving the dye uptake rate and color fastness of the fiber.

[0046] The easily dyeable polyurethane-urea elastic fiber of the present invention contains 1.0% to 5.0% of a dyeing assistant, calculated based on the total mass of the easily dyeable polyurethane-urea elastic fiber;

[0047] Preferably, the fiber further contains a fixing agent and / or a brightening agent;

[0048] The mass content of the fixing agent is 0.2% to 1.0%, calculated based on the total mass of the easily dyeable polyurethane-urea elastic fiber;

[0049] The mass content of the brightening agent is 0.05% to 0.20%, calculated based on the total mass of the easily dyeable polyurethane-urea elastic fiber;

[0050] The fixing agent includes one or more of cetylpyridinium chloride, cetylpyridinium bromide, the condensate of dimethylamine and epichlorohydrin, the condensate of diethanolamine polyether and epichlorohydrin, and ethyl dimethylaminoethyl methacrylate quaternary ammonium salt;

[0051] The brightening agent includes one or more of polydimethylsiloxane, sodium diphenylstyrylbiphenyl disulfonate, 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, solvent blue 45, and phthalocyanine blue;

[0052] In the present invention, the addition of the fixing agent can act synergistically with the dyeing assistant to further improve the binding force between the dye and the fiber, reduce the dye migration rate, and further improve the color fastness of the finished spandex fabric after multiple washings and sun exposures.

[0053] In the present invention, the addition of the brightening agent can improve the problem of the deep color of the polyamide, make the prepared spandex product have good appearance whiteness, and thus reduce the influence of the product background color on subsequent dyeing.

[0054] The easily dyeable polyurethane-urea elastic fiber will include polyurethane-urea, a dyeing assistant, an optional fixing agent, and an optional brightening agent as spinning raw materials, and is obtained by dry spinning in the presence of a solvent.

[0055] The polyurethane-urea includes the reaction product of a polymer polyol, a polyisocyanate, a diamine chain extender, and a terminator;

[0056] The polymer polyol described above includes polyester polyol and / or polyether polyol. Further, the polymer polyol includes polyether polyol, and the polyether polyol includes one or more of polytetrahydrofuran diol, polyethylene glycol, or polypropylene glycol;

[0057] The number-average molecular weight of the polymer polyol is 1000 - 2000 g / mol;

[0058] The polyisocyanate includes one or more of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dimethylbiphenyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dicyclohexylmethane diisocyanate, and / or derivatives and / or modified polymers;

[0059] The diamine chain extender includes one or more of ethylenediamine, propylenediamine, 2-methyl-1,5-pentanediamine, pentanediamine, and hexamethylenediamine;

[0060] The terminator independently includes one or more of dimethylamine, diethylamine, dipropylamine, n-butanol, and ethanolamine;

[0061] The solvent includes one or more of N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylformamide.

[0062] As an example, the preparation method of the polyurethane-urea is as follows: React the polymer polyol and polyisocyanate described above to obtain a prepolymer mixture, dissolve it in the presence of a solvent to obtain a prepolymer solution, and react the prepolymer solution with a mixed amine solution containing a diamine chain extender and a terminator to obtain a polyurethane-urea spinning dope;

[0063] The NCO mass content of the prepolymer mixture is 2 wt% - 4 wt%;

[0064] The mass concentration of the prepolymer solution is 30 wt% - 60 wt%;

[0065] Control the molar ratio A / NCO of the amine end group (A) in the mixed amine to the isocyanate end group (NCO) in the prepolymer mixture to be 1.01 - 1.10; The molar ratio of the diamine chain extender to the terminator is 1:1 - 30:1;

[0066] The mass concentration of the mixed amine solution is 3 wt% - 10 wt%;

[0067] The mass concentration of the polyurethane-urea dope is 30 wt% - 45 wt%.

[0068] The preparation method of the easily dyed polyurethane-urea elastic fiber is as follows:

[0069] A solution containing a dyeing auxiliary, optionally a fixing agent, and optionally a brightening agent is added to the polyurethane-urea stock solution, and after thorough mixing and curing, a spinning dope is obtained.

[0070] Among them, the mass concentration of the solution containing the dyeing auxiliary, optionally the fixing agent, and optionally the brightening agent is 30-60%.

[0071] The spinning dope is conveyed by a metering pump, spun through a spinneret assembly, and formed through a spinning channel, a false-twist device, and a winding machine respectively to obtain easily dyeable polyurethane-urea elastic fibers.

[0072] Optionally, other common functional auxiliaries in the art can be added to the polyurethane-urea stock solution. There is no special requirement for the addition amount of the auxiliaries as long as the performance of the product is not deteriorated, such as one or more of antioxidants, ultraviolet absorbers, lubricants, chlorine-resistant auxiliaries, and cohesion auxiliaries.

[0073] The following examples are used to describe the production process of the present invention in detail, but these examples should not be construed as any limitation to the present invention.

[0074] Preparation of Dyeing Auxiliary 1:

[0075] 1) Add 314 g of octadecanedioic acid to a reaction kettle and stir thoroughly. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping a mixed solution of ethylenediamine and diethylenetriamine with a molar ratio of 1:1. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator, and then cool under vacuum to obtain a copolyamide with a chromaticity (iron-cobalt color number) of 5, an amine value of 31 mg KOH / g, an acid value of 0.5 mg KOH / g, and a number-average molecular weight of 1626 g / mol.

[0076] 2) React the copolyamide obtained above with an aqueous formaldehyde solution using formic acid as a catalyst at 50 °C for 10-12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and obtain Dyeing Auxiliary 1 with a hydroxyl value of 18 mg KOH / g after vacuum drying.

[0077] Preparation of Dyeing Auxiliary 2:

[0078] 1) Add 230 g of dodecanedioic acid into a reaction kettle and stir well. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping a mixed solution of ethylenediamine and diethylenetriamine with a molar ratio of 1:1. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator. After vacuumizing and cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 6, an amine value of 35 mg KOH / g, an acid value of 0.7 mg KOH / g is obtained, and its number-average molecular weight is 816 g / mol;

[0079] 2) React the copolyamide obtained above with an aqueous formaldehyde solution, using formic acid as a catalyst, and react at 50 °C for 10 - 12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and obtain dyeing auxiliary 2 with a hydroxyl value of 12 mg KOH / g after vacuum drying.

[0080] Preparation of dyeing auxiliary 3:

[0081] 1) Add 561 g of dimerized linoleic acid into a reaction kettle and stir well. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping a mixed solution of ethylenediamine and dihexenetriamine with a molar ratio of 1:2. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator. After vacuumizing and cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 5, an amine value of 31 mg KOH / g, an acid value of 0.4 mg KOH / g is obtained, and its number-average molecular weight is 2650 g / mol;

[0082] 2) React the polyamide obtained above with an aqueous formaldehyde solution, using formic acid as a catalyst, and react at 50 °C for 10 - 12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and obtain dyeing auxiliary 3 with a hydroxyl value of 20 mg KOH / g after vacuum drying.

[0083] Preparation of dyeing auxiliary 4:

[0084] Add 561 g of dimerized linoleic acid into a reaction kettle and stir well. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping a mixed solution of ethylenediamine and dihexenetriamine with a molar ratio of 1:2. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator. After vacuumizing and cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 5, an amine value of 31 mg KOH / g, an acid value of 0.4 mg KOH / g is obtained, and its number-average molecular weight is 2650 g / mol. Without hydroxyl modification, it is used as dyeing auxiliary 4.

[0085] Preparation of dyeing auxiliary 5:

[0086] 1) Add 561 g of dimerized linoleic acid to the reaction kettle and stir well. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping a mixed solution of ethylenediamine and dihexenetriamine with a molar ratio of 1:2. Reduce the molar ratio of the added mixed amine. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator. After vacuum cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 5, an amine value of 20 mg KOH / g, an acid value of 10 mg KOH / g, and a number-average molecular weight of 3710 g / mol is obtained;

[0087] 2) React the polyamide obtained above with an aqueous formaldehyde solution using formic acid as a catalyst and react at 50 °C for 10 - 12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and after vacuum drying, a dyeing auxiliary 5 with a hydroxyl value of 10 mg KOH / g is obtained.

[0088] Preparation of dyeing auxiliary 6:

[0089] 1) Add 561 g of dimerized linoleic acid to the reaction kettle and stir well. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping a mixed solution of ethylenediamine and dihexenetriamine with a molar ratio of 3:1. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator. After vacuum cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 5, an amine value of 10 mg KOH / g, an acid value of 0.4 mg KOH / g, and a number-average molecular weight of 4940 g / mol is obtained;

[0090] 2) React the polyamide obtained above with an aqueous formaldehyde solution using formic acid as a catalyst and react at 50 °C for 10 - 12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and after vacuum drying, a dyeing auxiliary 6 with a hydroxyl value of 5 mg KOH / g is obtained.

[0091] Preparation of dyeing auxiliary 7:

[0092] 1) Add 561 g of dimerized linoleic acid to the reaction kettle and stir well. Without the protection of a nitrogen atmosphere, directly heat up to 150 °C and start dropping a mixed solution of ethylenediamine and dihexenetriamine with a molar ratio of 1:2. After reacting at a constant temperature for 1 h, quickly heat up to 250 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets drip out from the water separator. After vacuum cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 10, an amine value of 31 mg KOH / g, an acid value of 0.4 mg KOH / g, and a number-average molecular weight of 2650 g / mol is obtained;

[0093] 2) React the polyamide obtained above with an aqueous formaldehyde solution using formic acid as a catalyst and react at 50 °C for 10 - 12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and after vacuum drying, a dyeing auxiliary 7 with a hydroxyl value of 20 mg KOH / g is obtained.

[0094] Preparation of Dyeing Auxiliary 8:

[0095] 1) Add 561 g of dimerized linoleic acid to a reaction kettle and stir well. Under the protection of a nitrogen atmosphere, slowly heat up to 130 °C and start dropping the DMAC solution of ethylenediamine. After reacting at a constant temperature for 1 h, quickly heat up to 230 °C and react at a constant temperature for 2 h. Stop heating until no obvious water droplets come out from the water separator. After vacuum cooling, a copolyamide with a chromaticity (iron-cobalt color number) of 5, an amine value of 24 mg KOH / g, an acid value of 0.7 mg KOH / g, and a number-average molecular weight of 2280 g / mol is obtained;

[0096] 2) React the copolyamide obtained above with an aqueous formaldehyde solution using formic acid as a catalyst at 50 °C for 10 - 12 h. Remove the unreacted formaldehyde and catalyst by precipitation, and obtain Dyeing Auxiliary 8 with a hydroxyl value of 14 mg KOH / g after vacuum drying.

[0097] Preparation of Polyurethane-Urea:

[0098] Mix polytetrahydrofuran ether diol with a number-average molecular weight of 1800 g / mol and 4,4'-diphenylmethane diisocyanate, and react at 45 °C for 2 h to obtain a polyurethane prepolymer mixture with an NCO mass content of 2.60%. Dissolve the polyurethane prepolymer mixture in a DMAc solution, add a DMAc mixed amine solution of ethylenediamine / diethylamine with a molar ratio of 15:1 for chain growth and chain termination reactions, and control the molar ratio A / NCO of the amine end groups (A) in the mixed amine to the isocyanate end groups (NCO) in the prepolymer mixture to be 1.02 to obtain a 35% mass concentration of polyurethane-urea stock solution.

[0099] Example 1

[0100] Preparation of Polyurethane-Urea Elastic Fiber: Add a solution containing Dyeing Auxiliary 1, a condensate of fixing agent dimethylamine and epichlorohydrin, and optical brightener Solvent Blue 45 to the polyurethane-urea stock solution, and obtain a spinning dope after fully mixing and curing for 12 h;

[0101] Among them, the mass concentration of the solution containing the dyeing auxiliary, the fixing agent, and the optical brightener is 40%; the dyeing auxiliary accounts for 2.5% of the fiber solid content, the fixing agent accounts for 0.25% of the fiber solid content, and the optical brightener accounts for 0.10% of the fiber solid content;

[0102] Adopt dry spinning technology, convey the spinning dope through a metering pump, spin and form through a spinneret hole assembly, and form through a spinning duct, a false-twist device, and a winding machine respectively to obtain 40D polyurethane-urea elastic fiber.

[0103] Example 2

[0104] The spandex fibers were prepared by the same method as described in Example 1, except that the dyeing assistant added was Dyeing Assistant 2, and the dyeing assistant accounted for 4.5% of the fiber solids content; the fixing agent added was ethyl dimethylaminoethyl methacrylate quaternary ammonium salt, and the brightening agent added was phthalocyanine blue, and the addition ratios remained unchanged.

[0105] Example 3

[0106] The spandex fibers were prepared by the same method as described in Example 1, except that the dyeing assistant added was Dyeing Assistant 3, the fixing agent added was the condensate of diethanolamine polyether and epichlorohydrin, and the brightening agent added was sodium diphenylstyryl biphenyl disulfonate, and the addition ratios remained unchanged.

[0107] Example 4

[0108] The spandex fibers were prepared by the same method as described in Example 3, except that the Dyeing Assistant 3 added accounted for 7.5% of the fiber solids content, and the other additives and addition ratios remained unchanged.

[0109] Example 5

[0110] The spandex fibers were prepared by the same method as described in Example 3, except that the Dyeing Assistant 3 added accounted for 0.25% of the fiber solids content, and the other additives and addition ratios remained unchanged.

[0111] Example 6

[0112] The spandex fibers were prepared by the same method as described in Example 3, except that Dyeing Assistant 4 was added, and the other additives and addition ratios remained unchanged.

[0113] Example 7

[0114] The spandex fibers were prepared by the same method as described in Example 3, except that no fixing agent was added, and the other additives and addition ratios remained unchanged.

[0115] Example 8

[0116] The spandex fibers were prepared by the same method as described in Example 3, except that no brightening agent was added, and the other additives and addition ratios remained unchanged.

[0117] Example 9

[0118] The spandex fibers were prepared by the same method as described in Example 3, except that Dyeing Assistant 5 was added, and the other additives and addition ratios remained unchanged.

[0119] Example 10

[0120] The spandex fibers were prepared by the same method as described in Example 3, except that Dyeing Assistant 6 was added, and the other additives and addition ratios remained unchanged.

[0121] Example 11

[0122] Spandex fibers were prepared by the same method as described in Example 3, except that dyeing assistant 7 was added and other additives and their addition ratios remained unchanged.

[0123] Example 12

[0124] Spandex fibers were prepared by the same method as described in Example 3, except that dyeing assistant 8 was added and other additives and their addition ratios remained unchanged.

[0125] Comparative Example 1

[0126] Using the dry spinning technique, without adding dyeing assistants, optical brighteners, and color fixatives, the polyurethane-urea spinning dope was directly transported through a metering pump, extruded through a spinneret assembly to form filaments, and then formed through a spinning duct, a false twister, and a winding machine to obtain 40D polyurethane-urea elastic fibers.

[0127] Comparative Example 2

[0128] Spandex fibers were prepared by the same method as described in Example 3, except that the added dyeing assistant was ground nylon 6 and other additives and their addition ratios remained unchanged.

[0129] Comparative Example 3

[0130] Spandex fibers were prepared by the same method as described in Example 3, except that the added dyeing assistant was ground nylon 610 and other additives and their addition ratios remained unchanged.

[0131] Comparative Example 4

[0132] Spandex fibers were prepared by the same method as described in Example 3, except that the added dyeing assistant was liquid polyamide 650 and other additives and their addition ratios remained unchanged.

[0133] The polyurethane-urea fibers prepared in the examples and comparative examples were respectively tested for chromaticity, mechanical properties, dye uptake rate, and color fastness. The test methods are as follows:

[0134] (1) Chromaticity (iron-cobalt color number):

[0135] By grinding the sample into powder and then pressing it into a sheet to obtain a uniform surface; under a D65 standard light source, comparing the sample with an iron-cobalt color card and selecting the closest color card as the iron-cobalt color number of the sample.

[0136] (2) Mechanical properties:

[0137] Test the breaking strength and elongation at break of the fiber samples according to the method provided in the industry standard FZ / T 50006-2013 "Test Method for Tensile Properties of Spandex Yarn".

[0138] Breaking strength: Under the specified tensile test conditions, record the maximum load that the specimen can withstand when stretched to breakage.

[0139] Elongation at break: Calculate the percentage of the elongation at break of the specimen to the initial length.

[0140] The clamp gauge length of the tensile testing machine is 50 ± 0.5 mm, and the tensile speed is 500 mm / min.

[0141] (3) Dye uptake rate:

[0142] Acid dye uptake rate: Dye for 30 min under the conditions of a weak acid red dye concentration of 2% (owf, relative to the fabric weight), a temperature of 100 °C, a pH value of 4.8, and a bath ratio of 1:40. Immerse the sample at 40 °C and increase the temperature at a rate of 1 °C / min. After dyeing, take out the sample, rinse it in clear water until the water does not change color, and then dry it at room temperature. Measure the maximum absorbance of the dye solution before and after dyeing using a UV-visible spectrophotometer, and calculate the acid dye uptake rate.

[0143] Reactive dye uptake rate: Dye for 60 min under the conditions of a reactive yellow dye concentration of 2% (owf, relative to the fabric weight), a temperature of 85 °C, a pH value of 7.0, and a bath ratio of 1:40. Immerse the sample at 40 °C and increase the temperature at a rate of 1 °C / min. After dyeing, take out the sample, rinse it in clear water until the water does not change color, and then dry it at room temperature. Measure the maximum absorbance of the dye solution before and after dyeing using a UV-visible spectrophotometer, and calculate the reactive dye uptake rate.

[0144] Dye uptake rate = A 0 - A 1 / A 0 × 100%, where A 0 and A 1 are the absorbances of the dye solution before and after dyeing, respectively.

[0145] (4) Color fastness:

[0146] Test the color fastness of the fiber samples after acid dyeing and reactive dyeing according to the method provided in GB / T 3921-2008 "Textiles - Tests for color fastness - Color fastness to soaping". When determining whether staining occurs, use the standard staining color card for staining to distinguish into 9 grades: 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5. The closer to grade 5, the less staining occurs.

[0147] The performance is shown in the following table:

[0148]

Claims

1. A dyeing auxiliary agent, characterized in that: The invention comprises a modified copolymer polyamide, wherein the copolymer polyamide comprises a reaction product of at least one aliphatic acid and at least one small molecule amine.

2. A dyeing auxiliary according to claim 1, characterized in that: The aliphatic acid includes an aliphatic polyacid having 12 to 36 carbon atoms, and further includes one or more of dodecanedioic acid, hexadecanedioic acid, octadecanedioic acid, eicosanedioic acid, docosenedioic acid, dimer fatty acid, and dimer linoleic acid.

3. A dyeing auxiliary according to claim 1, characterized in that: The small molecule amine includes a polyamine with a carbon number of 2 to 12, and further includes one or more of ethylenediamine, propylenediamine, pentylenediamine, hexamethylenediamine, diethylenetriamine, dipropylenetriamine, dihexylenetriamine, dibutylenetriamine, and triethylenetetramine.

4. A dyeing auxiliary according to claim 1, characterized in that: The number average molecular weight of the copolymer polyamide is 500-5000 g / mol; the acid value of the copolymer polyamide is below 1 mg KOH / g, and the amine value is 20-40 mg KOH / g; the chromaticity of the copolymer polyamide, i.e., the iron-cobalt color number, is 4-6.

5. A dyeing auxiliary according to claim 1, characterized in that: The modified copolymer polyamide is hydroxyl-modified, and the hydroxyl-modified copolymer polyamide is obtained by reacting an aldehyde aqueous solution with a copolymer polyamide resin in the presence of an acid catalyst.

6. A dyeing auxiliary according to claim 5, characterized in that: The aldehydes include one or more of formaldehyde, acetaldehyde and propionaldehyde; the acid catalysts include one or more of formic acid, sulfuric acid, hydrochloric acid and p-toluenesulfonic acid; and the hydroxyl value of the hydroxyl-modified copolymer polyamide is 10 to 30 mg KOH / g.

7. An easily dyeable polyurethane urea elastic fiber containing the dyeing auxiliary according to claim 1, characterized in that: The elastic fiber contains 1.0% to 5.0% of the dyeing auxiliary agent based on the total mass of the easily dyeable polyurethane urea elastic fiber.

8. The easily dyeable polyurethane urea elastic fiber according to claim 7, characterized in that: The elastic fiber also contains a fixing agent and / or a whitening agent, wherein the fixing agent has a mass content of 0.2% to 1.0%, calculated based on the total mass of the easily dyeable polyurethane urea elastic fiber; and the whitening agent has a mass content of 0.05% to 0.20%, calculated based on the total mass of the easily dyeable polyurethane urea elastic fiber.

9. The easily dyeable polyurethane urea elastic fiber according to claim 8, characterized in that: The color fixing agent includes at least one of cetylpyridinium chloride, cetylpyridinium bromide, a condensation product of dimethylamine and epichlorohydrin, a condensation product of diethanolamine polyether and epichlorohydrin, and a quaternary ammonium salt of dialkylaminoethyl methacrylate; the whitening agent includes at least one of polydimethylsiloxane, sodium distyrylbiphenyl disulfonate, 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene, solvent blue 45, and phthalocyanine blue.

10. A method for preparing the easily dyeable polyurethane urea elastic fiber as claimed in claim 7, characterized in that: The spinning raw materials include polyurethane-urea, dyeing auxiliary, optional fixing agent and optional brightening agent, and are obtained by dry spinning in the presence of a solvent; Wherein, the polyurethane-urea comprises the reaction product of a polymer polyol, a polyisocyanate, a diamine chain extender and a terminator; The polymer polyol includes polyester polyol and / or polyether polyol, the polymer polyol includes polyether polyol, and the polyether polyol includes one or more of polytetramethylene glycol, polyethylene glycol or polypropylene glycol; The polyisocyanate includes toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dimethylbiphenyl diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, dicyclohexylmethane diisocyanate and / or derivatives and / or modified polymers. The diamine chain extender includes one or more of ethylenediamine, propylenediamine, 2-methyl-1,5-pentanediamine, pentamethylenediamine, and hexamethylenediamine; The terminator includes one or more of dimethylamine, diethylamine, dipropylamine, n-butanol and ethanolamine.

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