Easily dyeable spandex and preparation method thereof

Abstract

According to the easy-to-dye spandex and the preparation method thereof provided by the invention, the polyether ester polyol with a specific structure is added into a diol raw material in a spandex preparation process, so that a molecular soft segment of the prepared spandex fiber contains a specific aromatic group-polyether block structure. Compared with conventional spandex, the easy-to-dye spandex has the advantages that the dye-uptake rate and the color fixing capacity of the spandex to disperse dyes and acid dyes can be increased under the condition that the mechanical property of the spandex is not lost. By adjusting the mass ratio of the aromatic group-polyether block structure in the spandex molecule soft segment, the spandex has better alkali resistance under the condition of sufficient dye uptake and fixation rate.

Description

Technical Field

[0001] The invention relates to the field of chemical fibers, and in particular to an easy-to-dye spandex and a preparation method of the easy-to-dye spandex. Background Art

[0002] Spandex, also known as polyurethane fiber, is the most widely used elastic fiber. In applications, spandex is rarely used as an independent fabric and is often blended with other types of fibers. The mainstream spandex on the market is polyether spandex made by dry spinning using polytetramethylene ether diol and diisocyanate as raw materials. Conventional spandex is usually dyed with disperse dyes or acid dyes. However, in actual use, the dyeing rate and color fastness of spandex are poor. After blending and dyeing with other fibers, color difference or "whitening" will occur, which has a great impact on the appearance of textile products. The reason is that the molecular structure of spandex is mainly composed of a polyether part with lower polarity and a polyurethane or polyurethane urea part with higher polarity. The polyether part of the mainstream spandex product is the residue of polytetramethylene ether diol, which belongs to the non-crystalline region in the microphase separation structure and has a loose structure. It provides elasticity for the spandex fiber and is the main site for dyeing with disperse dyes, but has weak binding force with disperse dyes. The polyurethane or polyurethane urea part can theoretically dye with acid, neutral, acidic medium and disperse dyes through hydrogen bonds and their coordination bonds, but because this part is the crystalline region, the molecular chain segments are stacked tightly, and it is difficult for dye molecules to diffuse into the interior of the crystalline region, which greatly reduces the dyeing rate.

[0003] Based on the above problems, the present invention provides an easily dyeable spandex, which improves the dyeing rate and color fixation ability of the spandex fiber to disperse dyes and acid dyes. Summary of the invention

[0004] An easily dyeable spandex, characterized in that the soft segment of the molecular structure of the easily dyeable spandex comprises a repeating unit described in the following formula (1):

[0005]

[0006] Wherein R1 is at least one of an aromatic ring and an aromatic heterocyclic ring, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a linear saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20;

[0007] The mass of the repeating unit represented by formula (1) accounts for more than 2%, preferably more than 5%, more preferably more than 10%, less than 70%, preferably less than 65% of the mass of the spandex soft segment.

[0008] Optionally, the soft segment of the molecular structure of the spandex further includes a polytetramethylene ether segment.

[0009] The soft segment mass in the present invention refers to the mass of the molecular structure of the part of the spandex after the diol raw material reacts with diisocyanate and the terminal hydroxyl group is removed. The diol raw material refers to the diol compound used as the raw material of the polyurethane molecular weight soft segment, including the polyether ester polyol defined in the present invention, and the optional polytetramethylene glycol and other substances, but does not include the small molecule diol compound used as the chain extender.

[0010] The high resilience coarse denier spandex can be prepared by dry spinning or melt spinning. Specifically, the preparation method of dry spinning is as follows:

[0011] A method for preparing easy-to-dye spandex, characterized in that it comprises the following steps:

[0012] Step 1): using a diisocyanate raw material to cap a diol raw material to prepare a prepolymer;

[0013] Step 2): dissolving the prepolymer using a polar solvent to obtain a prepolymer solution;

[0014] Step 3): using a mixed solution of a linker and a terminator to chain extend the prepolymer to obtain a polyurethane / polyurethane urea solution;

[0015] Step 4): adding an auxiliary agent to obtain a spinning solution;

[0016] Step 5): The obtained spinning solution is passed through a spinning device to obtain easily dyeable spandex.

[0017] The preparation method of melt spinning is as follows:

[0018] A method for preparing easy-to-dye spandex comprises the following steps:

[0019] Step a) adding a diisocyanate raw material, a diol raw material, and a small molecule polyol chain extender into a reaction container respectively;

[0020] Step b) mixing the materials in the reaction container, and heating the materials during or after the mixing process to react and extruding and granulating the materials to obtain polyurethane particles;

[0021] Step c) drying the polyurethane particles, adding an auxiliary agent and performing melt spinning to obtain easily dyeable spandex.

[0022] In one embodiment of the present invention, the diol raw material includes a polyether ester polyol having an aromatic group-polyether block structure, and the polyether ester polyol is composed of a repeating unit represented by formula (1) and a capped alcohol hydroxyl group:

[0023]

[0024] Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00; the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

[0025] Optionally, the polyetherester polyol is heated at 90°C and a shear rate of 1 s -1 The viscosity of the above-mentioned solvent may be less than 500 poise, preferably less than 200 poise.

[0026] Optionally, the mass ratio of the polyether ester polyol in the diol raw material is greater than 2%, preferably greater than 5%, and more preferably greater than 10%.

[0027] Optionally, the mass ratio of the polyether ester polyol in the diol raw material is less than 70%, preferably less than 65%.

[0028] Optionally, the diol raw materials also include other diol compounds that can be used as spandex soft segments, as the second type of diol raw materials, such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol and other polyether glycols, polybutylene adipate glycol, adipic acid and mixed diols (such as ethylene glycol / 1,4-butanediol, ethylene glycol / 1,2-propylene glycol, 1,6-hexanediol / 2,2-dimethylpropylene glycol-1,3) copolyester diols, other polyether ester diols that can be used as spandex soft segments, or a mixture of at least two of the above diol compounds.

[0029] Preferably, the mass of the second type of diol raw material accounts for 30%-95% of the total diol raw materials. That is, the preferred solution is that the polyol and the second type of diol raw material are blended as the diol raw material of spandex.

[0030] The preferred second type of diol starting material is furanyl ether diol.

[0031] In another embodiment of the present invention, the diol raw material includes a polyether ester polyol having an aromatic group-polyether block structure, and the polyether ester polyol comprises a repeating unit represented by formula (1) and a capped alcohol hydroxyl group:

[0032]

[0033] Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the mass percentage of the repeating unit represented by formula (1) in the polyether ester polyol is greater than 5%; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00, and the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

[0034] The polyetherester polyol may contain some other polyester structures or polyether structures, or some aliphatic structures as modified structures.

[0035] Likewise, the polyetherester polyols mentioned above can be blended with the second type of diol raw material mentioned above to serve as diol raw materials for spandex.

[0036] Beneficial effects:

[0037] The easy-dye spandex provided by the present invention is prepared by adding a polyether ester polyol of a specific structure to a diol raw material, so that the molecular soft segment of the prepared spandex fiber contains a specific aromatic group-polyether block structure, and the easy-dye spandex is spun. Compared with conventional spandex, the easy-dye spandex of the present invention can increase the dyeing rate and color fixing ability of the spandex to disperse dyes and acid dyes without losing the mechanical properties of the spandex.

[0038] By adjusting the mass ratio of the aromatic group-polyether block structure in the soft segment of the spandex molecule, the spandex has sufficient dyeing rate and fixation rate and better alkali resistance. DETAILED DESCRIPTION

[0039] The present invention provides an easy-to-dye spandex having good dye uptake and fixation ability for disperse dyes and acid dyes. The soft segment of the molecular structure of the easy-to-dye spandex comprises a repeating unit described in the following formula (1):

[0040]

[0041] Wherein R1 is at least one of an aromatic ring and an aromatic heterocyclic ring, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a linear saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20;

[0042] The mass of the repeating unit represented by formula (1) accounts for 5% or more, preferably 10% or more of the mass of the soft segment.

[0043] Optionally, the soft segment of the molecular structure of the spandex further includes a polytetramethylene ether segment.

[0044] For the convenience of description, the aromatic ring or aromatic heterocyclic ring represented by R1 is collectively referred to as an aromatic group herein.

[0045] Since the dye molecules of disperse dyes and acid dyes are all in the aqueous solution of dye molecules, all the dye molecules are dissolved in water. The glycol raw material used in ordinary spandex is polytetrahydrofuran, and the prepared polyurethane urea polymer has hydrophobicity. The molecular structure of the easy-to-dye spandex provided by the present invention has the above formula (1), wherein (R2-O) x The hydrophilicity of the molecular chain is increased. The structure is introduced into the spandex molecular structure by polyether ester polyol prepared by PEG and P3OG (polyethylene glycol and poly 1,3-propylene glycol, especially polyethylene glycol) and aromatic dibasic acid. Compared with polytetrahydrofuran, the above structure contains a higher density of ether oxygen bonds. The polyurethane urea polymer prepared by using the polyether ester polyol has stronger hydrophilicity, making it easier for spandex to be swollen by dye solution during acid dyeing and disperse dyeing, and the gap between molecules becomes larger, making it easier for dye molecules to enter the spandex yarn. In addition, since acid dye molecules and disperse dye molecules are mostly macromolecules containing aromatic rings, the aromatic ring structure introduced by polyether ester polyol has a stronger van der Waals force with the dye molecules, so that the dye molecules entering the spandex have a stronger interaction force with the polyether ester polyol, and are more easily fixed in the spandex molecules, thereby showing a higher dyeing rate and fixation rate for acid dye dyeing and disperse dye dye chromosomes.

[0046] While meeting the requirements of dye uptake and fixation rate of the dye, the introduction of the structure of formula (1) should avoid affecting the mechanical properties of spandex as much as possible. Therefore, the present invention makes more specific requirements for the structure of formula (1).

[0047] In the repeating unit shown in formula (1), when the content of the aromatic group R1 is too high, the molecular rigidity of the final spandex will be too large, affecting the elongation at break and the ability to resist plastic deformation of the spandex; when the content of the aromatic group R1 is too low, it will not play a role in reducing the permanent deformation rate of the spandex, and will also lead to a decrease in the recovery modulus of the spandex. Therefore, in the present invention, the mass content of R1 in the repeating unit is preferably 4.5% to 44%. Wherein R1 is at least one of an aromatic ring and an aromatic heterocyclic ring, and the aromatic ring can be at least one of an aromatic ring such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, etc.; the aromatic heterocyclic ring can be at least one of a pyridine, a furan ring, a thiazole ring, a pyrimidine ring, etc. In an optional embodiment, R1 includes 1-4 methylene groups in addition to the aromatic ring or the aromatic heterocyclic ring.

[0048] In the structure of formula (1) above, (R2-O) xThe structure actually represents a polyether segment, and the x in the polyether segment represents the degree of polymerization of the (R2-O) structure. The degree of polymerization x of the polyether segment is preferably 2-20, more preferably 3-10, and the molecular weight of the polyether segment can be 100-1000, preferably 300-1000, and more preferably 600-900. In fact, only when the degree of polymerization and number average molecular weight of the polyether segment are within the above range can the influence of the polyetherester structure on the mechanical properties of spandex be avoided as much as possible. (R2-O) x If the length of the polyether chain segment is too short, the spandex molecules produced will be too rigid, affecting the elongation at break of the spandex. x If the length of the chain segment is too long, it will have an adverse effect on the permanent deformation rate of spandex. In the polyether chain segment, R2 is preferably a straight-linked saturated alkane group with 2-3 carbon atoms. For the present invention, the fewer the number of carbon atoms in R2, the greater the density of the ether oxygen bond, which can make the water absorption of spandex stronger, and more conducive to the entry of dye molecules into the interior of the spandex fiber, which is conducive to improving the dyeing rate of spandex. The molecular structure containing branched chains will have an adverse effect on the water absorption of spandex. Therefore, in the present invention, R2 is preferably a straight-linked saturated alkane group, specifically, (R2-O) x It can be a polyether segment of PEG, a polyether segment of P3OG, or a polyether segment of ethylene glycol and 1,3-propylene glycol copolymer, among which a straight-chain saturated alkane group having 2 carbon atoms is most preferred.

[0049] In the spandex molecular structure of the present invention, the structure represented by formula (1) should account for a certain proportion in the soft segment to improve the dye uptake and fixation rate of spandex. In the present invention, the mass proportion of the structure represented by formula (1) in the soft segment should be greater than 2%, preferably greater than 5%, preferably greater than 10%, more preferably greater than 30%, and most preferably greater than 50%.

[0050] The polyether ester structure shown in formula (1) has little effect on the mechanical properties of spandex, so its mass proportion in the soft segment can be appropriately increased. However, due to the presence of ester groups in the structure, the spandex containing the structure has a certain gap in alkali resistance compared with the spandex made from polytetrahydrofuran ether diol, and may cause mechanical property losses during the dyeing and finishing process. Therefore, the mass proportion of the polyether ester structure shown in formula (1) in the spandex soft segment should not be too high, preferably less than 80%, more preferably less than 70%, and more preferably less than 65%. Specifically, spandex prepared from polyether ester polyol and spandex prepared from polyether polyol can be blended in the form of raw materials, prepolymers and polymers to improve the alkali resistance of spandex prepared from polyether ester polyol.

[0051] The present invention also provides a method for preparing the above-mentioned easy-to-dye spandex. The easy-to-dye spandex can be prepared by dry spinning or melt spinning, wherein the dry spinning comprises the following steps:

[0052] Step 1): using a diisocyanate raw material to cap a diol raw material to prepare a prepolymer;

[0053] Step 2): dissolving the prepolymer using a polar solvent to obtain a prepolymer solution;

[0054] Step 3): using a mixed solution of a linker and a terminator to chain extend the prepolymer to obtain a polyurethane / polyurethane urea solution;

[0055] Step 4): adding an auxiliary agent to obtain a spinning solution;

[0056] Step 5): The obtained spinning solution is passed through a spinning device to obtain easily dyeable spandex.

[0057] Compared with conventional spandex dry spinning, the improvement of the scheme of the present invention mainly lies in the change of diol raw materials.

[0058] In one embodiment of the present invention, the diol raw material includes a polyether ester polyol having an aromatic group-polyether block structure, and the polyether ester polyol is composed of a repeating unit represented by formula (1) and a capped alcohol hydroxyl group:

[0059]

[0060] Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00; the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

[0061] Optionally, the polyetherester polyol is heated at 90°C and a shear rate of 1 s -1 The viscosity of the above-mentioned solvent may be less than 500 poise, preferably less than 200 poise.

[0062] The polyether ester polyol can be subjected to a condensation reaction or an ester exchange reaction with an aromatic dibasic acid, its esterification product or its anhydride and a polyether diol. In one embodiment, the esterification product can be obtained by reacting an aromatic dibasic acid with a monohydric alcohol having a boiling point below 150°C, such as a small molecule alcohol such as methanol, ethanol, n-butanol, and n-hexanol, so that they can be easily removed by distillation in a subsequent esterification reaction or ester exchange reaction; the small molecule alcohol is preferably methanol or ethanol. Moreover, compared with aromatic dibasic acids, the ester exchange reaction between the above-mentioned esterification product and the polyether diol can be carried out under milder reaction conditions, which is conducive to the design of production process. The aromatic dibasic acid suitable for the present invention can be derived from recycled plastics, thereby achieving waste recycling and reducing the production cost of polyurethane fibers, which is more in line with the requirements of the current green economy.

[0063] In order to ensure that the dye molecules can more easily enter the spandex yarn, the polyether diol is preferably at least one of the directly connected saturated alkane groups with 2-3 carbon atoms. The high density of ether oxygen bonds can make the polyether segment more hydrophilic, which can make the spandex more easily swollen by the dye solution during acid dyeing and disperse dyeing, and the gap between molecules becomes larger, making it easier for the dye molecules to enter the spandex yarn. Specifically, the polyether diol can be polyethylene glycol (PEG), poly 1,3-propylene glycol (P3OG), or a copolyether diol of ethylene glycol and 1,3-propylene glycol. Preferably, the polyether diol is polyethylene glycol (PEG), which has a higher ether oxygen bond density, which can make the spandex more hydrophilic, so that the dye molecules can more easily enter the spandex yarn.

[0064] The aromatic dibasic acid can be selected from one or more of terephthalic acid, isophthalic acid, phthalic acid, biphenyl dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,5-furan dicarboxylic acid, terephthalic acid, isophthalic acid, and phthalic acid. Since acid dye molecules and disperse dye molecules are mostly macromolecules containing aromatic rings, the aromatic ring structure introduced by the polyether ester polyol has a stronger van der Waals interaction with the dye molecules, so that the dye molecules entering the spandex have a stronger interaction with the polyether ester chain segment and are more easily fixed in the spandex molecules. Therefore, under the joint action of the polyether chain segment and the aromatic ring structure, the spandex with the polyether-aromatic ring structure has a better dyeing rate and fixation rate than conventional spandex.

[0065] By using the polyetherester polyol containing the aromatic group-polyether block structure as the soft segment raw material of spandex, the structure described in formula (1) can be introduced into the molecular structure of spandex.

[0066] To ensure that the polyetherester segment does not have an adverse effect on the mechanical properties of spandex, the number average molecular weight of the polyetherester polyol described above should be 800-5000, preferably 1000-3500, more preferably 1400-2500, and most preferably 1500-2300. The larger the number average molecular weight of the polyetherester polyol, the greater its viscosity, and it is difficult to carry out continuous operation on an industrial scale. However, the molecular weight of the polyetherester polyol is too small. When the molecular weight requirements of the polyurethane prepolymer are consistent, more diisocyanates are required to participate in the synthesis, resulting in a high content of carbamate groups in the prepolymer, so the interaction between the prepolymer molecules is enhanced, the viscosity will also increase, and the soft segment length in the polyurethane formed at this time is shorter, which will affect the recovery performance of the final polyurethane fiber.

[0067] In the polyether ester polyols described above, the average functionality of the end-capped alcoholic hydroxyl groups can be 1.95-2.00, preferably 1.96-2.00, and more preferably 1.98-2.00, so that the polyether ester polyols can be smoothly end-capped with isocyanate and then chain extended by small molecule amines or alcohols. "Average functionality" refers to the average number of moles of alcoholic hydroxyl groups that can participate in the reaction per mole of polyether ester polyol. In the present invention, considering the dehydration of the end-hydroxyl groups of the polyether diol to form double bonds and the presence of unreacted carboxyl groups, the average functionality of the alcoholic hydroxyl groups can be calculated by the following formula:

[0068] Functionality = 2* moles of alcoholic hydroxyl groups / (moles of alcoholic hydroxyl groups + moles of carboxyl groups + moles of double bonds)

[0069] In the above polyether ester polyols, due to the presence of ester groups, if all of the polyether ester polyols are used as diol raw materials for spandex, the spandex will have a certain gap in alkali resistance compared with polyether spandex. Therefore, it is necessary to limit the mass ratio of the aromatic group-polyether block structure in the spandex soft segment. The specific way to control the mass ratio can be to blend the spandex prepared from the polyether ester polyol with the spandex prepared from the polyether polyol in the form of diol raw materials, prepolymers or polymers to improve the alkali resistance of the spandex prepared from the polyether ester polyol.

[0070] Taking the blending of glycol raw materials for spandex as an example, in order to make the spandex have better dyeing rate and fixation rate, the mass ratio of the polyether ester polyol in the glycol raw materials should be greater than 2%, preferably greater than 5%, preferably greater than 10%, more preferably greater than 20%, more preferably greater than 30%, more preferably greater than 40%, and most preferably greater than 50%.

[0071] In order to ensure the alkali resistance of the prepared spandex, the mass ratio of the polyether ester polyol in the diol raw material is less than 80%, preferably less than 70%, and more preferably less than 65%.

[0072] Optionally, in addition to the polyether ester polyols described above, the diol raw materials also include other diol compounds that can be used as spandex soft segments, as the second type of diol raw materials, such as polytetrahydrofuran ether diol, polyethylene glycol, polypropylene glycol and other polyether diols, polybutylene adipate diol, adipic acid and mixed diols (such as ethylene glycol / 1,4-butanediol, ethylene glycol / 1,2-propylene glycol, 1,6-hexanediol / 2,2-dimethylpropylene glycol-1,3) copolyester diols, and other polyether ester diols that can be used as spandex soft segments, or a mixture of at least two of the above diol compounds. In order to ensure the alkali resistance of spandex, polyether diols are preferably used as the second type of diol raw materials, and polytetrahydrofuran ether diol is most preferred. Preferably, the mass of the second type of diol raw materials accounts for 30%-98% of all diol raw materials, preferably 35%-90%. That is, a preferred solution is to blend the polyetherester polyol with the second type of diol raw material as the diol raw material for spandex.

[0073] The method of blending with prepolymers or polymers is similar to that described above and will not be described in detail here.

[0074] In order to ensure the alkali resistance of the obtained spandex, in another embodiment of the present invention, the diol raw material includes a polyether ester polyol of an aromatic group-polyether block structure, and the polyether ester polyol comprises a repeating unit represented by formula (1) and a capped alcohol hydroxyl group:

[0075]

[0076] Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the mass percentage of the repeating unit represented by formula (1) in the polyether ester polyol is greater than 2%, preferably greater than 5%, preferably greater than 10%; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00, and the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

[0077] Different from the method of blending polyether ester polyol with the second type diol raw material in the previous embodiment, this embodiment chooses to reduce the proportion of the cyclic structure in formula (1) in the polyether ester polyol. In order to balance the dyeing performance and alkali resistance of spandex, in a preferred embodiment, the mass ratio of the cyclic structure in formula (1) in the polyether ester polyol should be greater than 5%, preferably greater than 10%, more preferably greater than 30%, and most preferably greater than 50%. At the same time, it is preferably less than 80%, more preferably less than 70%, and more preferably less than 65%. The rest of the polyether ester polyol may have some other polyester structures or polyether structures, or some aliphatic structures as modified structures. In order to ensure the mechanical properties of spandex, a polyether structure is preferred, and a polytetramethylene ether structure is most preferred.

[0078] Likewise, the polyetherester polyols mentioned above can be blended with the second type of diol raw material mentioned above to serve as diol raw materials for spandex.

[0079] In the method for preparing easy-dye spandex of the present invention, the diisocyanate raw material in step 1) can be one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isomers thereof.

[0080] The polar solvent in step 2) is at least one of N,N-dimethylformamide and N,N-dimethylacetamide.

[0081] The chain extender in step 3) can be an amine or alcohol chain extender, wherein the amine chain extender can be a diamine with 2 to 30 carbon atoms, for example, it can be selected from one or more of ethylenediamine, propylenediamine, butylenediamine, pentylenediamine, methylpentylenediamine, methylpropylenediamine, hexylenediamine, triethylenediamine, benzylenediamine, phenylenediamine, diaminocyclohexane, hexamethylenediamine, and dopamine; the alcohol chain extender can be one or more of common chain extenders such as ethylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, 1,3-propylene glycol, and 1,4-dihydroxymethylcyclohexane. The chain terminator can be a monoamine having 2 to 20 carbon atoms, and can be selected from one or more of ethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, cyclohexylamine or ethanolamine.

[0082] Melt spinning includes the following steps:

[0083] Step a) adding a diisocyanate raw material, a diol raw material, and a small molecule polyol chain extender into a reaction container respectively;

[0084] Step b) mixing the materials in the reaction container, and heating the materials during or after the mixing process to react and extruding and granulating the materials to obtain polyurethane particles;

[0085] Step c) drying the polyurethane particles, adding an auxiliary agent and then performing melt spinning.

[0086] The raw materials for preparing the above-mentioned melt-spinning spandex, such as diisocyanate and diol raw materials, are similar to the raw materials for dry spinning, except that the chain extender in step a) is only an alcohol chain extender.

[0087] Example

[0088] The present invention is described in more detail below by way of examples, wherein the testing methods of the parameters involved are specifically as follows:

[0089] 1. Average functionality:

[0090] Functionality = 2* number of moles of alcoholic hydroxyl groups / (number of moles of alcoholic hydroxyl groups + number of moles of carboxyl groups + number of moles of double bonds).

[0091] The acid value is measured by the method described in HG / T 2708-1995; the hydroxyl value is measured by the method described in HG / T 2709 / 1995; and the unsaturation is measured by the method described in GB / T 12008.6-2010. The corresponding acid value, hydroxyl value, and unsaturation are converted into the molar number of the corresponding terminal groups in the polyetherester diol.

[0092] 2. 300% tensile stress, breaking strength and breaking elongation: all in accordance with the "Textile Industry Standard of the People's Republic of China" FZ / T 50006-2013, "Test method for tensile properties of spandex yarn".

[0093] 3. Dyeing rate of acid dyes and fixation rate after soaping:

[0094] In the present invention, acid red is used as an acid dye, the dye concentration in the dye liquor before dyeing is measured as A, the dye concentration after dyeing is measured as B, and the dye concentration in the washing liquor after soaping is measured as C, and the following is obtained:

[0095] Acid dye uptake = (AB) / A

[0096] Acid dye fixation rate after soaping = (ABC) / A

[0097] 4. Dyeing rate of disperse dyes and fixation rate after soaping:

[0098] In the present invention, disperse orange is used as a spinning dye, and the dye concentration in the dye liquor before dyeing is measured as P, the dye concentration after dyeing is measured as Q, and the dye concentration in the washing liquid after soaping is measured as M, and the following is obtained:

[0099] Disperse dye uptake = (PQ) / P

[0100] Disperse dye fixation rate after soaping = (PQM) / P

[0101] 5. Spandex hysteresis test:

[0102] In the present invention, the hysteresis degree of the fiber is characterized by the ratio of the tensile stress when stretched to 200% for the fifth time and the recovery stress when recovered to 200% for the fifth time through 5 stretching cycle tests, that is, the smaller the ratio, the more serious the hysteresis phenomenon of the spandex is, and the larger the ratio, the smaller the hysteresis phenomenon of the spandex is. Specifically, hereinafter, "5LP200%" represents the tensile stress value when stretched to 200% elongation for the fifth time, that is, F1, "5UP200%" represents the rebound stress value when recovered to 200% elongation for the fifth time, that is, F2; "5UP200% / 5LP 200%" represents the ratio of the recovery stress when recovered to 200% for the fifth time and the tensile stress when stretched to 200% for the fifth time in the 5 stretching cycle tests.

[0103] 6. Spandex alkali resistance test:

[0104] The spandex yarn was boiled in 10 g / L potassium hydroxide solution at 100 °C for 1 hour, and the mechanical properties before and after boiling in alkali solution were tested.

[0105] In addition, the antioxidant mentioned in the following examples is antioxidant 245, the dyeing aid is DH300R or 2462B, and the light stabilizer is Tinuvin 791, all of which are commercially available substances.

[0106] Example 1

[0107] 17 parts by weight of polyethylene glycol PEG600 (number average molecular weight of 600) and 2.7 parts by weight of terephthalic acid are added into a reactor, and nitrogen is passed through to replace the air in the reactor. The stirring in the reactor is turned on at a speed of 150 rpm. The system is subjected to a programmed temperature increase to 150°C and maintained for 5 hours; the temperature is continued to be increased to 230°C and maintained at this temperature until the water output rate of the system reaches more than 90% of the theoretical value and the solution becomes homogeneous, and the catalyst tetraisopropyl titanate is added and the solution is gradually evacuated to 2000Pa; when the acid value is lower than 0.5 mgKOH / g, a polyether ester diol with a number average molecular weight of 1500 is obtained. After testing, its average functionality is 1.98, 90°C 1S -1 The viscosity is 25 poise and it is liquid at room temperature.

[0108] Example 2

[0109] The polyether ester diol of Example 1 is used to prepare polyurethane elastic fiber

[0110] 100 kg of the polyether ester polyol prepared in Example 1 was added to a reactor which had been kept at a constant temperature of 45°C, stirring was started at a speed of 150 rpm, 31 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90°C; the reactor was reacted at 90°C for 2 hours to obtain a prepolymer.

[0111] The prepolymer was cooled to 50°C, 166.72 kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer, and then an amine solution containing 2.40 kg of ethylenediamine and 0.29 kg of diethylamine with a mass concentration of 3.2% was added, and the stirring speed was increased to 300 rpm to carry out a chain extension reaction. After the chain extension reaction was completed, necessary antioxidants, dyeing agents and other auxiliaries were added, and the spinning solution with a solid content of 35% was obtained after aging for 30 hours. The above solution was dry-spun to obtain a polyurethane elastic fiber PUU-1 with a denier of 40D.

[0112] Example 3

[0113] The polyetherester polyol of Example 1 and polytetrahydrofuran (PTMG) with a number average molecular weight of 2000 are used to prepare polyurethane fibers.

[0114] 50 kg of the polyether ester polyol prepared in Example 1 and 50 kg of polytetrahydrofuran with a number average molecular weight of 2000 were added to a reactor which had been kept at a constant temperature of 45° C., stirring was started at a speed of 150 rpm, 21.88 kg of diphenylmethane diisocyanate was added, and the mixture was stirred for 5 minutes and then heated to 90° C.; the mixture was reacted at 90° C. for 2 hours to obtain a prepolymer.

[0115] The prepolymer was cooled to 50°C, 161.3kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer, and then an amine solution containing 2.38kg of ethylenediamine and 0.29kg of diethylamine with a mass concentration of 3.26% was added, and the stirring speed was increased to 300rpm to carry out the chain extension reaction. After the chain extension reaction was completed, necessary antioxidants, dyeing agents and other auxiliaries were added (the amount of dyeing agents added was 1%, 2462B), and the spinning solution with a solid content of 35% was obtained after aging for 30 hours. The above solution was dry-spun to obtain a polyurethane elastic fiber PUU-2 with a denier of 40D.

[0116] Example 4

[0117] The prepolymer prepared from the polyetherester polyol of Example 1 and polytetrahydrofuran (PTMG) with a number average molecular weight of 2000 is used to prepare polyurethane fibers

[0118] 50 kg of the polyether ester polyol prepared in Example 1 was added to a reactor whose temperature had been kept at 45° C., stirring was started at a speed of 150 rpm, 15.64 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90° C.; the reactor was reacted at 90° C. for 2 hours to obtain prepolymer 1.

[0119] 50 kg of polytetrahydrofuran with a number average molecular weight of 2000 was added to a reactor whose temperature had been kept at 45°C, stirring was started at a speed of 150 rpm, 11.1 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90°C; it was reacted at 90°C for 2 hours to obtain prepolymer 2.

[0120] Prepolymer 1 and prepolymer 2 were cooled to 50°C and transferred to the same reactor. 161.3 kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer, and then an amine solution containing 2.38 kg of ethylenediamine and 0.29 kg of diethylamine with a mass concentration of 3.26% was added. The stirring speed was increased to 300 rpm to carry out the chain extension reaction. After the chain extension reaction was completed, necessary antioxidants, dyeing agents and other auxiliaries were added (the amount of dyeing agents added was 1%, 2462B), and the spinning solution with a solid content of 35% was obtained after aging for 30 hours. The above solution was dry-spun to obtain a polyurethane elastic fiber PUU-3 with a denier of 40D.

[0121] Example 5

[0122] 100 kg of the stock solution prepared in Example 2 and 100 kg of the stock solution prepared in Comparative Example 1 were blended to prepare a stock solution for preparing polyurethane fibers.

[0123] Take 100 kg of the stock solution PUU3 prepared in Example 8 and 100 kg of the stock solution PUU0 prepared in Comparative Example 1, mix them evenly by stirring in a reactor combined with static mixing, and dry-spin the above stock solutions to obtain a polyurethane elastic fiber PUU-4 with a denier of 40D.

[0124] Example 6

[0125] The polyetherester polyol of Example 1 and polytetrahydrofuran (PTMG) with a number average molecular weight of 2000 are used to prepare polyurethane fibers.

[0126] 10 kg of the polyether ester polyol prepared in Example 1 and 90 kg of polytetrahydrofuran with a number average molecular weight of 2000 were added to a reactor which had been kept at a constant temperature of 45° C., stirring was started at a speed of 150 rpm, 21.88 kg of diphenylmethane diisocyanate was added, and the mixture was stirred for 5 minutes and then heated to 90° C.; the mixture was reacted at 90° C. for 2 hours to obtain a prepolymer.

[0127] The prepolymer was cooled to 50°C, 161.3kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer, and then an amine solution containing 2.38kg of ethylenediamine and 0.29kg of diethylamine with a mass concentration of 3.26% was added, and the stirring speed was increased to 300rpm to carry out the chain extension reaction. After the chain extension reaction was completed, necessary antioxidants, dyeing agents and other auxiliaries were added (the amount of dyeing agents added was 1%, 2462B), and the spinning solution with a solid content of 35% was obtained after aging for 30 hours. The above solution was dry-spun to obtain a polyurethane elastic fiber PUU-5 with a denier of 40D.

[0128] Example 7

[0129] The polyetherester polyol of Example 1 and polytetrahydrofuran (PTMG) with a number average molecular weight of 2000 are used to prepare polyurethane fibers.

[0130] 65 kg of the polyether ester polyol prepared in Example 1 and 35 kg of polytetrahydrofuran with a number average molecular weight of 2000 were added to a reactor which had been kept at a constant temperature of 45° C., stirring was started at a speed of 150 rpm, 21.88 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90° C.; the reactor was reacted at 90° C. for 2 hours to obtain a prepolymer.

[0131] The prepolymer was cooled to 50°C, 161.3kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer, and then an amine solution containing 2.38kg of ethylenediamine and 0.29kg of diethylamine with a mass concentration of 3.26% was added, and the stirring speed was increased to 300rpm to carry out the chain extension reaction. After the chain extension reaction was completed, necessary antioxidants, dyeing agents and other auxiliaries were added (the amount of dyeing agents added was 1%, 2462B), and the spinning solution with a solid content of 35% was obtained after aging for 30 hours. The above solution was dry-spun to obtain a polyurethane elastic fiber PUU-6 with a denier of 40D.

[0132] Comparative Example 1

[0133] The polytetrahydrofuran (PTMG) stock solution with a number average molecular weight of 2000 is used to prepare polyurethane elastic fibers.

[0134] 100 kg of polytetrahydrofuran PTMG2000 (number average molecular weight of 2000) was added to a reactor that had been kept at a constant temperature of 45°C, and stirring was started at a speed of 150 rpm. 22.2 kg of diphenylmethane diisocyanate was added, stirred for 5 minutes, and then heated to 90°C, and reacted at 90°C for 2 hours to obtain a prepolymer.

[0135] The prepolymer was cooled to 50°C, 155.5 kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer, and then a 3.2% amine solution containing 2.26 kg of ethylenediamine and 0.28 kg of diethylamine was added, and the stirring speed was increased to 300 rpm to carry out a chain extension reaction. After the chain extension reaction was completed, necessary antioxidants, dyeing agents and other auxiliaries were added, and the spinning solution with a solid content of 35% was obtained after aging for 30 hours. The above solution was dry-spun to obtain a polyurethane elastic fiber PUU-0 with a denier of 40D.

[0136] According to the test method described above, the mechanical property test results of the polyurethane elastic fibers (i.e., spandex fibers) obtained in the above examples and comparative examples are summarized in the following table:

[0137] Table 1 Comparison of mechanical properties tests

[0138]

[0139] It can be seen from the above table that the spandex yarn prepared by the method of the present invention has no obvious decrease in mechanical properties compared with conventional polyether spandex.

[0140] According to the test method described above, the dyeing performance test results of the polyurethane elastic fibers (i.e., spandex yarns) obtained in the above examples and comparative examples are summarized in the following table:

[0141] Table 2 Comparison of dyeing properties of acid dyes

[0142] Acid dye staining Dyed silk mass, g Dyeing rate, % Fixation rate after soaping, % PUU-0 1.32 10.68 5.63 PUU-1 1.33 62.45 41.35 PUU-2 1.31 31.25 23.25 PUU-3 1.32 32.23 22.13 PUU-4 1.33 29.25 20.16 PUU-5 1.33 15.61 9.30 PUU-6 1.34 43.50 30.21

[0143] Table 3 Comparison of dyeing properties of disperse dyes

[0144] Acid dye staining Dyed silk mass, g Dyeing rate, % Fixation rate after soaping, % PUU-0 1.51 15.2 7.65 PUU-1 1.53 56.48 42.65 PUU-2 1.55 31.25 24.12 PUU-3 1.54 33.13 23.15 PUU-4 1.52 28.15 22.16 PUU-5 1.51 20.03 11.94 PUU-6 1.49 42.87 29.87

[0145] It can be seen from the above table that the spandex yarn prepared by the method of the present invention has significantly improved dyeing rate and fixation rate of acid dyes and disperse dyes compared with conventional polyether spandex.

[0146] According to the test method described above, the alkali resistance test results of the polyurethane elastic fibers (i.e., spandex fibers) obtained in the above examples and comparative examples are summarized in the following table:

[0147] Table 4 Alkali resistance test comparison

[0148]

[0149]

[0150] It can be seen from the above table that after boiling with alkali solution, the mechanical properties of PUU-1, which is made entirely of polyether ester polyol as the soft segment raw material, partially deteriorated, while the mechanical properties of PUU-2 to PUU-6, which are mixed soft segment raw materials, changed less than before alkali boiling.

[0151] It can be seen from the above test results that the easy-dye spandex provided by the present invention significantly improves the dyeing rate and fixation rate of spandex yarn to acid dyes and disperse dyes, compared with conventional spandex, while ensuring the mechanical properties. By adjusting the formula, the problem of deterioration of the alkali resistance of spandex yarn is also avoided, and the requirements of mechanical properties, dyeability and alkali resistance of spandex yarn can be met.

Claims

1. An easy-to-dye spandex, characterized in that: The soft segment of the molecular structure of the easily dyeable spandex comprises a repeating unit represented by the following formula (1): Wherein R1 is at least one of an aromatic ring and an aromatic heterocyclic ring, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a linear saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20; The mass of the repeating unit represented by formula (1) accounts for more than 2% and less than 70% of the mass of the spandex soft segment.

2. The easy-to-dye spandex according to claim 1, characterized in that: The soft segment of the molecular structure of the spandex further comprises a polytetramethylene ether segment.

3. A method for preparing easy-to-dye spandex, characterized in that: The steps include: Step 1): using a diisocyanate raw material to cap a diol raw material to prepare a prepolymer; Step 2): dissolving the prepolymer using a polar solvent to obtain a prepolymer solution; Step 3): using a mixed solution of a linker and a terminator to chain extend the prepolymer to obtain a polyurethane / polyurethane urea solution; Step 4): adding an auxiliary agent to obtain a spinning solution; Step 5): the obtained spinning solution is passed through a spinning device to obtain easy-to-dye spandex; The diol raw materials include polyether ester polyols having an aromatic group-polyether block structure.

4. The method for preparing the easily dyeable spandex according to claim 3, characterized in that: The polyetherester polyol is composed of a repeating unit and a capped alcohol hydroxyl group as shown in formula (1): Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00; the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

5. The method for preparing the easily dyeable spandex according to claim 4, characterized in that: The mass ratio of the polyether ester polyol in the diol raw material is greater than 5% and less than 70%.

6. The method for preparing the easily dyeable spandex according to claim 4, characterized in that: The diol raw materials also include one or more of polytetramethylene glycol, polyethylene glycol, polypropylene glycol, polybutylene adipate glycol, adipic acid and copolyester diol of mixed diols.

7. The method for preparing the easily dyeable spandex according to claim 3, characterized in that: The diol raw material includes a polyether ester polyol having an aromatic group-polyether block structure, and the polyether ester polyol comprises a repeating unit represented by formula (1) and a capped alcohol hydroxyl group: Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the mass percentage of the repeating unit represented by formula (1) in the polyether ester polyol is greater than 5% and less than 70%; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00, and the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

8. A method for preparing easily dyeable spandex, characterized in that: The steps include: Step a) adding a diisocyanate raw material, a diol raw material, and a small molecule polyol chain extender into a reaction container respectively; Step b) mixing the materials in the reaction container, and heating the materials during or after the mixing process to react and extruding and granulating the materials to obtain polyurethane particles; Step c) drying the polyurethane particles, adding an auxiliary agent and performing melt spinning to obtain easily dyeable spandex; Wherein, the diol raw material includes polyether ester polyol with an aromatic group-polyether block structure.

9. The method for preparing the easily dyeable spandex according to claim 8, characterized in that: The polyetherester polyol is composed of a repeating unit and a capped alcohol hydroxyl group as shown in formula (1): wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a linear saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the average functionality of the capped alcohol hydroxyl group is 1.95 to 2.00; the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300; The mass ratio of the polyether ester polyol in the diol raw material is greater than 5% and less than 70%.

10. The method for preparing the easily dyeable spandex according to claim 8, characterized in that: The polyetherester polyol comprises a repeating unit and a capped alcohol hydroxyl group as shown in formula (1): Wherein R1 is at least one of an aromatic ring and an aromatic heterocycle, and the mass content of R1 in the repeating unit is 4.5% to 44%; R2 is at least one of a straight-linked saturated alkane group having 2 to 3 carbon atoms; x is 2 to 20, preferably 3 to 10; the mass percentage of the repeating unit represented by formula (1) in the polyether ester polyol is greater than 5%; the average functionality of the end-capped alcohol hydroxyl group is 1.95 to 2.00, and the number average molecular weight of the polyether ester polyol is 800 to 5000, preferably 1000 to 3500, more preferably 1400 to 2500, and most preferably 1500 to 2300.

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