Acid dyeable melt-spun spandex and preparation method thereof

Abstract

The invention discloses acid dyeable melt-spun spandex and a preparation method thereof, and belongs to the technical field of fiber manufacturing. A preparation method of acid dyeable melt-spun spandex comprises the following steps that melt-spun spandex slices are extruded and plasticized through a single screw, a cross-linking agent is added, and the acid dyeable melt-spun spandex is prepared through melt spinning; the melt spinning spandex slices contain carbodiimide groups; the cross-linking agent contains a carbodiimide group and tertiary amine ester. According to the invention, a tertiary amino structure is introduced into the cross-linking agent and then is further introduced into spandex macromolecules, so that a dyeing seat of an acid dye is provided, and the prepared acid dyeable spandex has very good washing color fastness. According to the invention, a high-rigidity carbodiimide structure is introduced into spandex macromolecules, so that the heat resistance of the acid dyeable spandex is improved, elasticity loss is avoided during sizing at 170-180 DEG C, and the requirement of nylon blending sizing is met.

Description

Technical Field

[0001] This invention belongs to the field of fiber manufacturing technology, and in particular relates to an acid-dyeable melt-spun spandex and its preparation method. Background Technology

[0002] In the weaving of spandex elastic fabrics, direct weaving with bare yarn is rare; most are used in the form of core-spun yarn and covered yarn. Therefore, the dyes used for dyeing are generally determined by the fibers mixed with spandex. For example, disperse dyes are used for polyester / spandex fabrics, neutral dyes for cotton / spandex fabrics, and acid dyes for nylon / spandex fabrics.

[0003] Studies have shown that spandex achieves a high equilibrium dye uptake of 70%-80% when dyed with acidic dyes in a weakly acidic bath. However, after soaping, the dye uptake drops to 56%-58%. Cross-section observation reveals that almost all the dye remaining on the fiber after soaping is transferred to the fiber surface. This results in poor lightfastness of spandex dyed with acidic dyes. The reason for this problem is that under acidic conditions, the imine groups in spandex bind protons, becoming positively charged and forming dye sites that bind acidic dyes. These sites can adsorb the anionic sulfonic acid groups in the acidic dyes. However, during soaping, the pH of the solution inside the spandex increases, causing the imine groups to lose protons, i.e., losing the positively charged dye sites that bind acidic dyes. Simultaneously, the soft chain segments of the spandex macromolecules, which have a very low glass transition temperature and are non-crystallizable, undergo violent motion, insufficient to bind the acidic dyes. This causes the acidic dyes to quickly diffuse from the fiber interior to the fiber surface and desorb into the solution. Therefore, conventionally soaped spandex exhibits poor colorfastness and is unsuitable for dyeing with acidic dyes.

[0004] Currently, dry spinning can improve the dyeing performance of spandex by introducing amide groups into the spandex macromolecule. For example, patents CN202011352833.6, CN202011262690.X and CN201710938274.9 directly add polyamide or modified polyamide to the spinning solution; patents CN202280061764.4 and CN202180085995.4 add carboxylic acid to the spinning solution. The carboxylic acid reacts with the primary and secondary amine groups in the spinning solution to form amide groups. However, none of the above methods are suitable for melt spinning. Therefore, there is an urgent need in the field for a melt-spun spandex suitable for acid dyes. Summary of the Invention

[0005] To address the above problems, this invention provides an acid-dyeable melt-spun spandex and its preparation method.

[0006] One of the technical solutions provided by this invention:

[0007] A method for preparing acid-dyeable melt-spun spandex includes the following steps: plasticizing melt-spun spandex chips by single-screw extrusion, adding a crosslinking agent, and obtaining the acid-dyeable melt-spun spandex by melt spinning; the melt-spun spandex chips contain carbodiimide groups; the crosslinking agent contains carbodiimide groups and tertiary amine esters.

[0008] Furthermore, the chemical structural formula of the carbodiimide group is as follows:

[0009]

[0010] The chemical structural formula of the tertiary amino ester is:

[0011] Wherein, R1 is a straight-chain or branched alkylene group with 2-6 carbon atoms, selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, or n-hexyl.

[0012] Furthermore, the mass ratio of the melt-spun spandex chips to the crosslinking agent is (85-90):(10-15).

[0013] Furthermore, the melt-spun spandex chips are selected from polyether-type melt-spun spandex chips, polyester-type melt-spun spandex chips, or ester-ether mixed-type melt-spun spandex chips.

[0014] Furthermore, the preparation method of the polyether-type melt-spun spandex chips or polyester-type melt-spun spandex chips includes the following steps: adding antioxidants and internal lubricants to polyether polyols or polyester polyols to obtain component A; adding component A, carbodiimide-modified isocyanate and chain extender to a twin-screw extruder; after melt reaction, adding external lubricants and UV agents; reacting extrusion; drying and curing to prepare the polyether-type melt-spun spandex chips or polyester-type melt-spun spandex chips, wherein the molecular weight of the polyether polyol is 600-3000; and the molecular weight of the polyester polyol is 600-6000, preferably 1500-5000.

[0015] Furthermore, the mass ratio of component A, chain extender, and carbodiimide-modified isocyanate is (63-73):(3.5-9.0):(17-32).

[0016] The chain extender includes one or more of the following: ethylene glycol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,2-propanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 1,6-hexanediol, 1,3-propanediol, 3-methyl-1,5-pentanediol, spirodiol, HQEE (hydroquinone dihydroxyethyl ether), resorcinol dihydroxyethyl ether, cyclohexanediol, and bisphenol A dihydroxyethyl ether.

[0017] The antioxidants include one or more of antioxidants 1010, 1076, 1024, GA-80, 168, Revonox 420, Revonox 501, PDP, or 626.

[0018] The UV stabilizers include hindered amines, benzophenones, or benzotriazoles, such as light stabilizers 622, UV1355, 770, 292, UV3030, UV903, UV-123, UV3, UVT, and UV234.

[0019] The matting agent is a titanium dioxide-based matting agent.

[0020] The lubricant includes one or more of EBS, EBO, oleamide, hydroxyethyl ethylene bis-stearamide, hydroxy silicone oil, stearic acid, calcium stearate, zinc stearate, or magnesium stearate.

[0021] Furthermore, the polyether polyol includes one or more of polytetrahydrofuran polyol, polyethylene glycol, tetrahydrofuran, and ethylene oxide copolymer polyol; and / or, the polyester polyol includes one or more of polyester polyol synthesized from diacids and diols or polycarbonate polyols.

[0022] The dicarboxylic acid includes one or more of adipic acid, sebacic acid, terephthalic acid, or succinic acid; the diol includes one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentanediol, or 1,6-hexanediol.

[0023] Further, the preparation method of the crosslinking agent includes the following steps: at 40-70°C, a macromolecular polyol with a tertiary amine ester is added to a carbodiimide-modified isocyanate, the mixture is stirred and reacted, the temperature is lowered to 40-50°C for further aging, and then the mixture is degassed under vacuum at 40-50°C to obtain the crosslinking agent.

[0024] Furthermore, the macromolecular polyol with tertiary amine ester is a hydroxyl-terminated polyester polyol synthesized from a derivative of diethanolamine and a dicarboxylic acid, and the molecular weight of the polyester polyol is 650-4000.

[0025] Furthermore, the diethanolamine derivatives include one or more of N-methyldiethanolamine, N-ethyldiethanolamine, N-n-propyldiethanolamine, N-isopropyldiethanolamine, N-n-butyldiethanolamine, N-isobutyldiethanolamine, N-tert-butyldiethanolamine, N-pentyldiethanolamine, or N-hexyldiethanolamine; and / or, the dicarboxylic acid includes adipic acid or sebacic acid.

[0026] The isocyanates required for preparing the crosslinking agent and melt-spun spandex chips in this invention include one or more of the following: MDI (diphenylmethane diisocyanate), toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, terephthalic diisocyanate, 1,4-cyclohexane diisocyanate, phenylenediamine diisocyanate, cyclohexanediamine diisocyanate, norbornene diisocyanate, and lysine diisocyanate.

[0027] Carbodiimide-modified MDI is a type of liquefied MDI. It is produced by partially condensing the NCO groups on the MDI molecule into carbodiimide under high temperature and catalysis. Further controlled reaction conversion transforms the carbodiimide portion into a trifunctional urea-ketimide. Existing carbodiimide-modified MDIs contain 28%-31% NCO, including those from BASF 103C, Covestro CD-C, Wanhua 100LL, Tosoh MX, Mitsui LL, Dow 143LP, and Huntsman 2020.

[0028] The second technical solution provided by this invention:

[0029] An acid-dyeable melt-spun spandex prepared by the above method. After dyeing with acid dyes, it exhibits uniform and consistent dyeing with nylon, excellent color fastness after soaping, and retains its elasticity and can form a web under heat setting conditions of 170-180℃.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] This invention introduces a tertiary amine structure into a crosslinking agent, and then further into the spandex macromolecule, providing a dyeing seat for acid dyes. The prepared acid-dyeable spandex has excellent wash fastness.

[0032] This invention introduces a high-rigidity carbodiimide structure into the spandex macromolecule, improving the heat resistance of acid-dyeable spandex and preventing loss of elasticity during setting at 170-180℃, thus satisfying the requirements for blending and setting of nylon.

[0033] This invention introduces a carbodiimide structure into the spandex molecular chain. During dyeing, the carbodiimide structure reacts with the carboxyl groups generated by the hydrolysis of spandex chips to form amide bonds. On the one hand, this provides a dyeing site for acid dyes, producing excellent acid-dyeable spandex. On the other hand, it improves the hydrolysis resistance of spandex and prevents the spandex from losing elasticity during high-temperature dyeing.

[0034] The present invention introduces a carbodiimide structure into the spandex molecular chain, which continues to react with the carboxyl groups generated by the hydrolysis of spandex in subsequent operations, generating amide bonds, providing a dyeing seat for acid dyes, and improving the color fastness to washing.

[0035] The acid-dyeable spandex prepared by this invention has long-lasting hydrolysis resistance and does not lose elasticity due to dyeing hydrolysis, which can meet the requirements of re-dyeing. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 DSC test curves of melt-spun spandex chips prepared in Examples 1-3 and Comparative Example 4;

[0038] Figure 2 The images are photographs of Examples 10, 12, 3, and 7 after staining. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] Unless otherwise specified, "parts" in this embodiment of the invention refers to "parts by mass".

[0045] This invention provides a method for preparing melt-spun spandex chips, the specific preparation process of which is as follows:

[0046] a. Obtain the raw material system, add antioxidants and internal lubricants to the polymer to form component A, and keep it at 100-120℃; add carbodiimide-modified isocyanate and keep it at 40-80℃ to form component B; use a small molecule chain extender as component C; the polymer is selected from polyether polyols or polyester polyols.

[0047] b. Components A, B, and C are added to a twin-screw extruder via a filling machine. After melting and reacting, other auxiliaries are added, followed by reaction extrusion. The mixture is then dried and cured in a drying oven to obtain melt-spun spandex chips. The external lubricant used for melt-spun spandex chips is added directly at the small feed port of the twin-screw extruder. Other auxiliaries include lubricants, anti-hydrolysis agents, and matting agents. The mass ratio of polymer, antioxidant, lubricant, UV stabilizer, anti-hydrolysis agent, and matting agent is 97.5-99.5:0.3-2.0:0.3-1.0:0-1.0:0-1.0:0-3.0. In some preferred embodiments, the mass ratio of component A, chain extender, and carbodiimide-modified isocyanate is (63-73):(3.5-9.0):(17-32).

[0048] In some preferred embodiments, the polyether polyol includes one or more of polytetrahydrofuran polyol, polyethylene glycol, tetrahydrofuran, and ethylene oxide copolymer polyol; and / or, the polyester polyol includes one or more of polyester polyol or polycarbonate polyol synthesized from diacids and diols; the diacid includes one or more of adipic acid, sebacic acid, terephthalic acid, or succinic acid; the diol includes one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentanediol, or 1,6-hexanediol. For example, the polyester polyol is PMPA-4000, a polyester polyol with a molecular weight of 4000 synthesized from adipic acid and 3-methyl-1,5-pentanediol, or PCL-3000, a polycarbonate polyol with a molecular weight of 2000 based on 1,5-pentanediol, and the polyether polyol is PTMEG-1800 (polytetrahydrofuran ether diol).

[0049] The hardness of the melt-spun spandex chips prepared in the embodiments of the present invention is 81-84A, and the DSC melting point is 178-185℃.

[0050] The present invention also provides a method for preparing a crosslinking agent, comprising the following steps: at 40-70°C, a macromolecular polyol with a tertiary amine ester is added to a carbodiimide-modified isocyanate, the mixture is stirred and reacted, the temperature is lowered to 40-50°C for further aging, and then the mixture is degassed under vacuum at 40-50°C to obtain the crosslinking agent.

[0051] In some preferred embodiments, the macromolecular polyol with a tertiary amine ester is a hydroxyl-terminated polyester polyol synthesized from a derivative of diethanolamine and a dicarboxylic acid; the diethanolamine derivative includes one or more of N-methyldiethanolamine, N-ethyldiethanolamine, N-n-propyldiethanolamine, N-isopropyldiethanolamine, N-n-butyldiethanolamine, N-isobutyldiethanolamine, N-tert-butyldiethanolamine, N-pentyldiethanolamine, or N-hexyldiethanolamine; and / or, the dicarboxylic acid includes adipic acid or sebacic acid. Exemplarily, the hydroxyl-terminated polyester polyol is adipic acid and N-methyldiethanolamine to synthesize polyester polyols PEA-800, PEA-1000, PEA-2000, or PEA-3000, or sebacic acid and N-ethyldiethanolamine to synthesize PEA-1000.

[0052] This invention also provides an acid-dyeable melt-spun spandex, prepared by a melt spinning process:

[0053] The dried melt-spun spandex chips are metered by a loss-in-weight pump and injected into a single-screw extruder according to the specified ratio to obtain a homogeneous melt. The temperatures of sections 1 to 7 of the screw extruder are 190℃, 200℃, 210℃, 220℃, 220℃, 210℃, and 210℃, respectively. The melt is pressurized by a melt pump and then filtered through a filter screen to obtain a refined melt. The crosslinking agent is preheated to 80-120℃ and metered by a metering pump, then fed into a static mixer along with the refined melt. After the refined melt and crosslinking agent are mixed evenly in the static mixer, gel impurities are removed by a filter screen, and the melt filaments are extruded through a spinneret. The filaments are then cooled by an annular blower, oiled with spinning oil, and then subjected to traction, guiding, and winding processes to obtain acid-dyeable melt-spun spandex.

[0054] In some preferred embodiments, the mass ratio of the melt-spun spandex chips to the crosslinking agent is (85-90):(10-15). For example, the mass ratio of the melt-spun spandex chips to the crosslinking agent is 90:10 or 85:15.

[0055] Example 1

[0056] This embodiment uses polyether polyols to prepare polyether-type melt-spun spandex chips. The specific preparation method includes the following steps:

[0057] S1. Weigh 0.77% of antioxidant 1076, 0.46% of Revonox 420 (antioxidant), and 0.46% of hydroxyethyl ethylene bis-stearamide (internal lubricant) and add them to 98.31% PTMEG-1800 (polytetrahydrofuran ether glycol) to obtain component A, and keep it at 110°C; keep Wanhua 100LL at 60°C to obtain component B, and keep ethylene glycol (chain extender) at 60°C to obtain component C;

[0058] S2. The mass ratio of component A: component C: component B is controlled at 64.71:3.98:30.21. The mixture is added to a two-stage twin-screw extruder via a filling machine. 0.3 parts of UV1355 (UV agent), 0.3 parts of 292 (UV agent), and 0.5 parts of calcium stearate (external lubricant) are added to the rear section of the second screw. The temperature of the first screw is controlled at 200-270℃, and the temperature of the second screw is controlled at 140-240℃. The mixture is reacted and extruded, then dried in a drying oven (80℃, 48h) to obtain polyether-type melt-spun spandex chips, denoted as melt-spun spandex chip Chip1, with a hardness of 84A and a DSC melting point of 180.5℃.

[0059] Example 2

[0060] This embodiment uses polyester polyols to prepare polyester melt-spun spandex chips. The polyester polyol PMPA-4000 with a molecular weight of 4000 is synthesized using adipic acid and 3-methyl-1,5-pentanediol. The specific preparation method includes the following steps:

[0061] S1. Weigh 0.69% of antioxidant 1076, 0.42% of Revonox 420 and 0.42% of hydroxyethyl ethylene bis-stearamide and add them to 98.47% of PMPA-4000 to obtain component A, and keep it at 110℃; keep Wanhua 100LL at 60℃ to obtain component B, and keep HQEE (chain extender) at 130℃ to obtain component C;

[0062] S2. The mass ratio of component A: component C: component B is controlled at 71.97:8.5:18.43. The mixture is added to a two-stage twin-screw extruder via a filling machine. 0.3 parts UV1355, 0.3 parts 292, and 0.5 parts calcium stearate are added to the rear section of the second screw. The temperature of the first screw is controlled at 200-270℃, and the temperature of the second screw is controlled at 140-240℃. The mixture is then reacted and extruded, and dried in a drying oven (80℃, 48h) to obtain polyester melt-spun spandex chips, denoted as melt-spun spandex chip Chip2. Its hardness is 83A, and its DSC melting point is 183.2℃.

[0063] Example 3

[0064] This embodiment uses 1,5-pentanediol-based polycarbonate polyol PCL-2000 with a molecular weight of 2000 to prepare polyester melt-spun spandex chips. The specific preparation method includes the following steps:

[0065] S1. Weigh 0.76% of antioxidant 1076, 0.46% of Revonox 420, and 0.46% of hydroxyethyl ethylene bis-stearamide and add them to 98.32% PCL-2000 to obtain component A, and keep it at 110℃; keep Wanhua 100LL at 60℃ to obtain component B; keep 1,3-propanediol (chain extender) at 60℃ to obtain component C;

[0066] S2. The mass ratio of component A: component C: component B is controlled at 65.65:4.5:28.61. The mixture is added to a two-stage twin-screw extruder via a filling machine. 0.3 parts UV1355, 0.3 parts 292, and 0.5 parts calcium stearate are added to the rear section of the second screw. The temperature of the first screw is controlled at 200-270℃, and the temperature of the second screw is controlled at 140-240℃. The mixture is then reacted and extruded, and dried in a drying oven (80℃, 48h) to obtain polyester melt-spun spandex chips, denoted as melt-spun spandex chip Chip3. Its hardness is 81A, and its DSC melting point is 180.1℃.

[0067] Comparative Example 1

[0068] This comparative example uses polyester polyols to prepare polyester melt-spun spandex chips. The polyester polyol PMPA-4000 with a molecular weight of 4000 was synthesized using adipic acid and 3-methyl-1,5-pentanediol. The specific preparation method includes the following steps:

[0069] S1. Weigh 0.68% of antioxidant 1076, 0.41% of Revonox 420 and 0.41% of hydroxyethyl ethylene bis-stearamide and add them to 98.50% PMPA-4000 to obtain component A, and keep it at 110℃; keep pure MDI at 60℃ to obtain component B, and keep HQEE (chain extender) at 60℃ to obtain component C;

[0070] S2. The mass ratio of component A: component C: component B is controlled at 74.03:8.72:16.05. The mixture is added to a two-stage twin-screw extruder via a filling machine. 0.3 parts UV1355, 0.3 parts 292, and 0.5 parts calcium stearate are added to the rear section of the second screw. The temperature of the first screw is controlled at 200-270℃, and the temperature of the second screw is controlled at 140-240℃. The mixture is then reacted and extruded, and dried in a drying oven (8℃, 48h) to obtain polyester melt-spun spandex chips, denoted as melt-spun spandex chip Chip4, with a hardness of 82A and a DSC melting point of 168.8℃.

[0071] Figure 1The image shows the DSC melting point test results of the melt-spun spandex chips prepared in Examples 1-3 and Comparative Example 1.

[0072] Example 4

[0073] At 60℃, a polyester polyol PAA-800 with a molecular weight of 800, synthesized from adipic acid and N-methyldiethanolamine, was added to Wanhua 100L. The mass ratio of PAA-800 to Wanhua 100L was controlled at 400:300. The mixture was stirred and reacted for 30 min, then cooled to 45℃ and allowed to mature for 48 h. Finally, it was degassed under vacuum at 45℃ to obtain crosslinking agent 1 with an NCO content of 5.9%.

[0074] Example 5

[0075] At 60℃, a polyester polyol PAA-1000 with a molecular weight of 1000, synthesized from adipic acid and N-methyldiethanolamine, was added to Wanhua 100LL. The mass ratio of PAA-1000 to Wanhua 100LL was controlled at 500:300. The mixture was stirred and reacted for 30 min, then cooled to 45℃ and allowed to mature for 48 h. Finally, it was degassed under vacuum at 45℃ to obtain crosslinking agent 2 with an NCO content of 5.2%.

[0076] Example 6

[0077] At 60℃, a polyester polyol PAA-2000 with a molecular weight of 2000, synthesized from adipic acid and N-methyldiethanolamine, was added to Wanhua 100LL. The mass ratio of PEA-2000 to Wanhua 100LL was controlled at 1000:300. The mixture was stirred for 30 min, cooled to 45℃ and matured for 48 h. Then, it was degassed under vacuum at 45℃ to obtain crosslinking agent 3 with an NCO content of 3.2%.

[0078] Example 7

[0079] At 60℃, a polyester polyol PAA-3000 with a molecular weight of 3000, synthesized from adipic acid and N-methyldiethanolamine, was added to Wanhua 100LL. The mass ratio of PAA-3000 to Wanhua 100LL was controlled at 1500:300. The mixture was stirred and reacted for 30 min, then cooled to 45℃ and allowed to mature for 48 h. Finally, it was degassed under vacuum at 45℃ to obtain crosslinking agent 4 with an NCO content of 2.2%.

[0080] Example 8

[0081] At 60℃, PAS-1000, a polyester polyol with a molecular weight of 1000 synthesized from sebacic acid and N-ethyldiethanolamine, was added to Wanhua 100LL. The mass ratio of PAS-1000 to Wanhua 100LL was controlled at 500:300. The mixture was stirred and reacted for 30 min. The temperature was then lowered to 45℃ and allowed to mature for 48 h. Finally, the mixture was degassed under vacuum at 45℃ to obtain crosslinking agent 5 with an NCO content of 5.3%.

[0082] Comparative Example 2

[0083] At 60℃, a polyester polyol POA-800 with a molecular weight of 800, synthesized from adipic acid and 1,5-pentanediol, was added to pure MDI. The mass ratio of POA-800 to pure MDI was controlled at 400:250. The mixture was stirred and reacted for 30 min, then cooled to 45℃ and allowed to mature for 48 h. Finally, the mixture was degassed under vacuum at 45℃ to obtain crosslinking agent 6 with an NCO content of 6.1%.

[0084] Example 9

[0085] S1. Dry Chip1 with nitrogen gas until the moisture content is below 0.03%;

[0086] S2. The dried Chip1 is metered by a loss-in-weight pump and injected into a single-screw extruder according to the formula to melt and plasticize to obtain a homogeneous melt. The temperatures of sections 1-7 of the screw extruder are 190℃, 200℃, 210℃, 220℃, 220℃, 210℃, and 210℃, respectively. The melt is pressurized by a melt pump and then filtered through a filter screen to obtain refined Chip1 melt.

[0087] S3. Preheat crosslinking agent 1 to 100°C, and pump it together with the refined melt prepared in S2 into a static mixer, controlling the crosslinking agent 1 to account for 10% and the refined melt of Chip 1 to account for 90%.

[0088] S4.Chip1 refined melt and crosslinking agent 1 are mixed evenly in a static mixer, then gel impurities are removed by a filter screen, and fine filament melt is spun out through a spinneret. The filament melt is cooled by an annular blower, oiled with spinning oil, and then traction, guiding, and winding processes are performed to prepare acid-dyeable melt-spun spandex 1.

[0089] Example 10

[0090] Same as Example 9, except that Chip1 prepared in Example 1 is replaced with Chip2 prepared in Example 2 to prepare acid-dyeable melt-spun spandex 2.

[0091] Example 11

[0092] Same as Example 9, except that Chip1 is replaced with Chip3 to prepare acid-dyeable melt-spun spandex 3.

[0093] Example 12

[0094] Same as Example 10, except that crosslinking agent 1 is replaced with crosslinking agent 2 to prepare acid dyeable melt-spun spandex 4.

[0095] Example 13

[0096] Same as Example 10, except that 85% Chip2 and 15% crosslinking agent 2 are added to prepare acid-dyeable melt-spun spandex 5.

[0097] Example 14

[0098] Same as Example 10, except that crosslinking agent 1 is replaced with crosslinking agent 3 to prepare acid-dyeable melt-spun spandex 6.

[0099] Example 15

[0100] Same as Example 10, except that crosslinking agent 1 is replaced with crosslinking agent 4 to prepare acid dyeable melt-spun spandex 7.

[0101] Example 16

[0102] Same as Example 10, except that crosslinking agent 1 is replaced with crosslinking agent 5 to prepare acid dyeable melt-spun spandex 8.

[0103] Comparative Example 3

[0104] Same as Example 10, except that crosslinking agent 1 is replaced with 5130 (Dow) was used to prepare melt-spun spandex 9.

[0105] Comparative Example 4

[0106] Same as Example 12, except that 95% Chip2 and 5% crosslinking agent 2 are added to prepare melt-spun spandex 10.

[0107] Comparative Example 5

[0108] Same as Example 12, except that 80% Chip2 and 20% crosslinking agent 2 are added to prepare melt-spun spandex 11.

[0109] Comparative Example 6

[0110] Same as Example 12, except that Chip2 is replaced with Chip4 to prepare melt-spun spandex 12.

[0111] Comparative Example 7

[0112] Same as Example 12, except that crosslinking agent 2 is replaced with crosslinking agent 7 to prepare melt-spun spandex 13.

[0113] Table 1 shows the raw materials and amounts used for the melt-spun spandex prepared in Examples 9-16 and Comparative Examples 3-7.

[0114] Table 1

[0115]

[0116] Acid-dyeable melt-spun spandex 1-13 was cured for one week at 30℃ and 80% humidity for performance verification. The coefficient of variation (CV), 300% elastic recovery rate, and mechanical properties of the melt-spun spandex were tested according to FZ / T54010 "Spandex Filament". The melt-spun spandex and cotton fiber were woven into high-elastic fabrics on a circular knitting machine. A small-scale setting machine was used, with setting temperatures of 170℃ and 180℃, for setting tests. Acid Blue 113 (CAS No. 3351-05-1) was used, with a liquor ratio of 1:20, dyeing pH of 4.5, and 10% spandex and 90% nylon added for dyeing. The heating rate was 1℃ / min, the dyeing temperature was 90℃, and the dyeing time was 40 minutes. Figure 2 The images are of Examples 10, 12, Comparative Example 3 and Comparative Example 7 after staining. The test results are shown in Table 2.

[0117] Table 2

[0118]

[0119] As shown in Table 2, the acid-dyeable spandex prepared by simultaneously introducing tertiary amine ester and carbodiimide groups in Examples 9-16 exhibited dyeing effects consistent with nylon, without color interference, and showed good results. Furthermore, it showed good web formation at 170℃-180℃, demonstrating excellent setting effects. Comparative Example 3 used a commercially available crosslinking agent, resulting in poor dyeability and almost no coloring. Comparative Example 4 reduced the crosslinking agent content, leading to a lower dyeing rate and lower heat resistance; slight loss of elasticity occurred at 180℃ setting. Comparative Example 5 increased the crosslinking agent content, resulting in a normal dyeing rate, but the spandex filament had a high CV value and poor strength. Comparative Example 6 used MDI instead of carbodiimide-modified MDI to prepare chips; the spandex suffered significant performance loss after dyeing, exhibiting poor hydrolysis resistance, slight loss of elasticity at 170℃ setting, and complete loss of elasticity at 180℃ setting, indicating poor heat resistance. Comparative Example 7 used 1,5-pentanediol instead of diethanolamine derivatives, lacking tertiary amine ester groups, and similarly showed almost no coloring.

[0120] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing acid-dyeable melt-spun spandex, characterized in that, Includes the following steps: The acid-dyeable melt-spun spandex chips are plasticized by single-screw extrusion, crosslinking agent is added, and the chips are melt-spun to obtain the acid-dyeable melt-spun spandex. The melt-spun spandex chips contain carbodiimide groups. The crosslinking agent contains carbodiimide groups and tertiary amine esters.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the melt-spun spandex chips to the crosslinking agent is (85-90):(10-15).

3. The preparation method according to claim 1, characterized in that, The melt-spun spandex chips are selected from polyether-type melt-spun spandex chips, polyester-type melt-spun spandex chips, or ester-ether mixed-type melt-spun spandex chips.

4. The preparation method according to claim 3, characterized in that, The preparation method of the polyether-type melt-spun spandex chips or polyester-type melt-spun spandex chips includes the following steps: adding antioxidants and internal lubricants to polyether polyols or polyester polyols to obtain component A; adding component A, carbodiimide-modified isocyanate and chain extender to a twin-screw extruder; after melt reaction, adding external lubricants and UV agents; reacting extrusion; drying and curing to prepare the polyether-type melt-spun spandex chips or polyester-type melt-spun spandex chips.

5. The preparation method according to claim 4, characterized in that, The mass ratio of component A, chain extender, and carbodiimide-modified isocyanate is (63-73):(3.5-9.0):(17-32).

6. The preparation method according to claim 4, characterized in that, The polyether polyol includes one or more of polytetrahydrofuran polyol, polyethylene glycol, tetrahydrofuran, and ethylene oxide copolymer polyol; and / or, the polyester polyol includes one or more of polyester polyol or polycarbonate polyol synthesized from diacids and diols; the diacid includes one or more of adipic acid, sebacic acid, terephthalic acid, or succinic acid; the diol includes one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentanediol, or 1,6-hexanediol.

7. The preparation method according to claim 1, characterized in that, The preparation method of the crosslinking agent includes the following steps: at 40-70°C, a macromolecular polyol with a tertiary amine ester is added to a carbodiimide-modified isocyanate, the mixture is stirred and reacted, the temperature is lowered to 40-50°C for further aging, and then the mixture is degassed under vacuum at 40-50°C to obtain the crosslinking agent.

8. The preparation method according to claim 7, characterized in that, The macromolecular polyol with tertiary amine esters is a hydroxyl-terminated polyester polyol synthesized from a derivative of diethanolamine and a dicarboxylic acid.

9. The preparation method according to claim 8, characterized in that, The derivatives of the diethanolamine include one or more of N-methyldiethanolamine, N-ethyldiethanolamine, N-n-propyldiethanolamine, N-isopropyldiethanolamine, N-n-butyldiethanolamine, N-isobutyldiethanolamine, N-tert-butyldiethanolamine, N-pentyldiethanolamine, or N-hexyldiethanolamine; and / or, the dicarboxylic acid includes adipic acid or sebacic acid.

10. An acid-dyeable melt-spun spandex prepared by the preparation method according to claims 1-9.

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