Low-temperature spandex blended and shaped with PLA fibers and preparation method of low-temperature spandex

Abstract

The invention discloses low-temperature spandex blended and shaped with PLA fibers and a preparation method of the low-temperature spandex, and relates to the technical field of fiber manufacturing. The special low-temperature spandex capable of being blended and shaped with the PLA fiber is prepared by designing a synergistic compounding system of the polyether type melt-spun spandex slices, the polyester type melt-spun spandex slices and the NCO-terminated prepolymer, and the technical problems that when the PLA fiber is independently used, the skin-friendly performance is poor, the elasticity is insufficient, and when common spandex is subjected to white exposure or color grabbing during blending dyeing are effectively solved. According to the low-temperature spandex blended and shaped with the PLA fiber, the spandex can be netted at the shaping temperature of 120-140 DEG C, namely, the spandex has the effect of being freely cut and cut, uniform coloring of the spandex and the PLA fiber in the dyeing process is achieved, the problem that traditional spandex is uneven in color due to the difference of dye affinity is solved, and the low-temperature spandex is suitable for being used in the dyeing process. The industrial requirements of functional textiles on the consistency of comfort, elasticity, processability and dyeing property can be met.

Description

Technical Field

[0001] This invention relates to the field of fiber manufacturing technology, and in particular to a low-temperature spandex blended and shaped with PLA fiber and its preparation method. Background Technology

[0002] Polylactic acid (PLA) fiber, or PLA fiber for short, is a fiber obtained from crops such as corn through fermentation, condensation, polymerization reactions, and melt spinning processes.

[0003] Based on the skin-friendly properties of PLA fiber, and the moisture-wicking, quick-drying, lightweight, and warming functions offered by its special cross-section, PLA fiber will be widely used in a range of apparel and textile products, including sportswear, school uniforms, underwear, home furnishings, children's clothing, gloves, socks, and thermal clothing. The natural antibacterial, anti-mite, mildew-resistant, and flame-retardant properties of PLA fiber also make it suitable for decorative textiles (indoor products, bedding, and outdoor products), including carpets, sofa covers, curtains, towels, bath towels, sheets, duvet covers, comforters, pillowcases, quilt inserts, hotel linens, and outdoor carpets, tents, and other related products.

[0004] PLA fiber, due to its high crystallinity, high rigidity, and poor toughness, suffers from poor skin-friendliness when used alone. The solution is to blend PLA fiber with spandex to produce elastic core-spun yarn. Spandex filament is used as the core yarn, and PLA filament as the outer sheath fiber, resulting in PLA / spandex elastic core-spun yarn with better elasticity, abrasion resistance, and a superior hand feel than ordinary short-fiber yarn. PLA fiber has a relatively low glass transition temperature (Tg) and melting temperature (Tm), at 57℃ and 175℃ respectively. Therefore, the pre-setting temperature is generally selected at 120-130℃, the post-setting temperature at 135℃, and the setting time at 30-45 seconds. However, commercially available spandex generally cannot meet these setting conditions. PLA fiber is typically dyed with disperse dyes. Ordinary polyether spandex has poor dyeability, and blending it with PLA results in white showing during dyeing. While ordinary polyester spandex dyes quickly, blending it with PLA can lead to color competition, making it difficult to meet current requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature spandex blended and shaped with PLA fibers and its preparation method, so as to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] One of the technical solutions of this invention is to provide a low-temperature spandex blended and shaped with PLA fiber, wherein the raw materials include the following components by weight:

[0008] 15-30 parts of polyether-type melt-spun spandex chips, 60-80 parts of polyester-type melt-spun spandex chips, 3.5-7.5 parts of NCO-terminated prepolymer, and 1-2 parts of spinning oil;

[0009] The DSC melting point of the polyether-type melt-spun spandex chips is 165-175℃, and the glass transition temperature is -65℃ to -55℃.

[0010] The DSC melting point of the polyester melt-spun spandex chips is 110-120℃, and the glass transition temperature is -50℃ to -40℃.

[0011] The terminal NCO prepolymer is obtained by reacting castor oil, N,N'-di-tert-butylethylenediamine and MDI-50, with an NCO content of 4.5% to 4.8%.

[0012] The introduction of N,N'-di-tert-butylethylenediamine can partially end-cap the NCO prepolymer, increasing its lifespan. The long-chain fatty acid structure in castor oil can impart reactive activity to the NCO, improving the degree of crosslinking in the final spandex filament.

[0013] The low-temperature spandex blended and shaped with PLA fiber in this invention is obtained by blending two spandex fibers with different DSC melting points under the crosslinking of NCO prepolymer.

[0014] As a further preferred embodiment of the present invention, the MI of the polyether-type melt-spun spandex chips is 20-30 g / 10 min (190℃*2.16 kg), and the hardness is 82-84A; the MI of the polyester-type melt-spun spandex chips is 20-30 g / 10 min (200℃*2.16 kg), and the hardness is 82-84A.

[0015] As a further preferred embodiment of the present invention, the reaction raw materials for the polyether-type melt-spun spandex chips include polytetrahydrofuran polyol, MDI and 1,4-butanediol.

[0016] As a further preferred embodiment of the present invention, the molecular weight of the polytetrahydrofuran polyol (PTMEG) is 1400-2100; the molar ratio of the polytetrahydrofuran polyol to 1,4-butanediol is 1:1.4 to 1:2.2.

[0017] The polytetrahydrofuran polyol (PTMEG) can be commercially available, such as PTMEG-1400, PTMEG-1800, PTMEG-1840, and PTMEG-2000 produced by manufacturers like BASF; it can also be a mixture of PTMEG with a molecular weight less than 1400 and PTMEG with a molecular weight greater than 1400, such as mixing PTMEG-1000 and PTMEG-2000 in a 1 / 2 molar ratio to obtain PTMEG with a molecular weight of 1500.

[0018] As a further preferred embodiment of the present invention, the reaction raw materials for the polyester melt-spun spandex chips include polyester polyol, chain extender and MDI.

[0019] As a further preferred embodiment of the present invention, the polyester polyol has a molecular weight of 3800-4500; the polyester polyol is obtained by reacting sebacic acid, 2-butyl-2-ethyl-1,3-propanediol and 1,6-hexanediol.

[0020] To improve the resilience of polyester melt-spun spandex chips, the molecular weight of the high-molecular-weight polyester polyol used is typically increased. However, excessively high molecular weight can cause the soft segments of the polyester melt-spun spandex chips to crystallize, resulting in a loss of elasticity. This invention utilizes a polyester polyol prepared by reacting sebacic acid with 2-butyl-2-ethyl-1,3-propanediol and 1,6-hexanediol. By introducing branching while mixing the polyacids, the soft segment crystallization of the polyester melt-spun spandex chips is disrupted, thereby increasing the resilience of the polyester chips.

[0021] As a further preferred embodiment of the present invention, the molar ratio of 2-butyl-2-ethyl-1,3-propanediol and 1,6-hexanediol is 1:1 to 1:2; the chain extender is 3-methyl-1,5-pentanediol; and the molar ratio of the polyester polyol and the chain extender is 1:3.7 to 1:4.8.

[0022] As a further preferred embodiment of the present invention, the raw materials also include one or more of antioxidants, UV stabilizers, carbodiimide anti-hydrolysis agents, titanium dioxide matting agents, and lubricants.

[0023] As a further preferred embodiment of the present invention, the antioxidant is 0.5 to 1.5 parts by weight, the carbodiimide anti-hydrolysis agent is 0.3 to 1.2 parts, the UV stabilizer is 0.5 to 1.2 parts, the lubricant is 0.0 to 1.0 parts, and not 0, and the titanium dioxide matting agent is 0.0 to 2.0 parts.

[0024] The antioxidants include antioxidant 1010, antioxidant GA-80, antioxidant 168, antioxidant Revonox 420, Revonox 501, PDP, and antioxidant 626, etc.

[0025] The UV stabilizers include hindered amines, benzophenones, and benzotriazoles, such as light stabilizer 622, light stabilizer 770, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (HA-10), UV3030, UV903, UV-123, UV1, UV3, and UVT.

[0026] The lubricants include EBS, EBO, oleamide, modified EBS, stearic acid, calcium stearate, zinc stearate, magnesium stearate, etc.

[0027] The second technical solution of the present invention provides a method for preparing the above-mentioned low-temperature spandex blended and shaped with PLA fiber, comprising the following steps:

[0028] The polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips are mixed and melt-plasticized to obtain a mixed melt.

[0029] The spinning oil and NCO-terminated prepolymer are preheated to 100-120°C and mixed with the mixed melt to prepare a filamentous melt. The melt is then subjected to cooling, oiling, drawing, guiding and winding processes to obtain a spandex fiber filament cake.

[0030] The spandex fiber cake is cured to obtain the low-temperature spandex that is blended and shaped with PLA fiber.

[0031] As a further preferred embodiment of the present invention, before mixing and melting the polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips, the present invention further includes a step of drying the polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips to a moisture content of less than 0.03%.

[0032] As a further preferred embodiment of the present invention, the curing temperature is 30°C and the humidity is 80%. The curing time is one week.

[0033] As a further preferred embodiment of the present invention, the polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips are mixed and then melt-plasticized in a single-screw extruder; the single-screw extruder adopts a 7-stage temperature control, and the temperatures of stages 1 to 7 are 180℃, 190℃, 200℃, 210℃, 210℃, 200℃, and 200℃, respectively.

[0034] This invention employs a blend of polyether-type melt-spun spandex chips and polyester-type melt-spun spandex chips for spinning. By limiting the ratio of the two types of chips, the compatibility of the prepared spandex yarn with disperse dyes is adjusted, thereby controlling the dyeing effect after blending with PLA, ensuring neither white showing nor color interference. This invention uses chips with two different DSC melting points to ensure that the spun spandex yarn achieves both increased viscosity and prevents filament breakage during setting at 120℃~140℃, guaranteeing high elasticity after setting.

[0035] This invention introduces a crosslinking agent with high NCO content. By limiting the molecular content (MI) of the two types of chips, both types of chips can react with the crosslinking agent, linking the two types of chips intermolecularly, improving chip compatibility, and thus improving the weavability of low-temperature spandex.

[0036] The spinning oil of the present invention is first mixed with a crosslinking agent, which reduces the viscosity of the crosslinking agent system and increases the oil content of the prepared low-temperature spandex. This can reduce the friction in the low-temperature spandex spinning process and improve the efficiency of later use.

[0037] The present invention discloses the following technical effects:

[0038] This invention designs a synergistic compounding system of polyether-type melt-spun spandex chips, polyester-type melt-spun spandex chips, and NCO-terminated prepolymers to prepare a special low-temperature spandex that can be blended and shaped with PLA fibers. This effectively solves the technical problems of poor skin affinity and insufficient elasticity when PLA fibers are used alone, as well as the white showing or color stealing of ordinary spandex during blending and dyeing.

[0039] The low-temperature spandex blended and shaped with PLA fibers provided by this invention can form a web at a setting temperature of 120-140℃, allowing for arbitrary cutting and trimming. Furthermore, the resulting spandex fibers not only achieve uniform dyeing of both spandex and PLA fibers during the dyeing process, avoiding the uneven coloring problem caused by differences in dye affinity in traditional spandex, but also ensure that the spandex and PLA fibers prepared by this invention can be machine-woven with a draw ratio of 3.0 or higher. The fabric retains the environmentally friendly characteristics of PLA while compensating for its elasticity and tactile deficiencies, significantly improving the overall performance of the blended fabric and meeting the industrial demands for comfort, elasticity, and dyeing consistency in functional textiles. Attached Figure Description

[0040] 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.

[0041] Figure 1 The stitching effect of the high-elastic fabric woven in Embodiment 2 and Comparative Example 3 after setting at 140°C is shown.

[0042] Figure 2 The results are those of Example 2 and Comparative Example 2 after staining.

[0043] Figure 3 The image shows the unraveling effect of the high-elastic fabric woven in Example 8 of this invention after being set at 140°C.

[0044] Figure 4 These are the DSC spectra of the five slices used in this invention. Detailed Implementation

[0045] 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.

[0046] 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. Any stated value or intermediate value within a stated range, as well as each smaller range between 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.

[0047] 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.

[0048] 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 readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0049] 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.

[0050] In this invention, unless otherwise specified, "parts" refers to parts by weight.

[0051] One objective of this invention is to provide a low-temperature spandex blended and shaped with PLA fibers, wherein the raw materials comprise the following components by weight:

[0052] 15-30 parts of polyether-type melt-spun spandex chips, 60-80 parts of polyester-type melt-spun spandex chips, 3.5-7.5 parts of NCO-terminated prepolymer, and 1-2 parts of spinning oil;

[0053] The DSC melting point of the polyether-type melt-spun spandex chips is 165-175℃, and the glass transition temperature is -65℃ to -55℃.

[0054] The DSC melting point of the polyester melt-spun spandex chips is 110-120℃, and the glass transition temperature is -50℃ to -40℃.

[0055] The terminal NCO prepolymer is obtained by reacting castor oil, N,N'-di-tert-butylethylenediamine and MDI-50, with an NCO content of 4.5% to 4.8%.

[0056] The introduction of N,N'-di-tert-butylethylenediamine can partially end-cap the NCO prepolymer, increasing its lifespan. The long-chain fatty acid structure in castor oil can impart reactive activity to the NCO, improving the degree of crosslinking in the final spandex filament.

[0057] The low-temperature spandex blended and shaped with PLA fiber in this invention is obtained by blending two spandex fibers with different DSC melting points under the crosslinking of NCO prepolymer.

[0058] Preferably, the MI of the polyether-type melt-spun spandex chips is 20-30 g / 10 min (190℃*2.16 kg), and the hardness is 82-84A; the MI of the polyester-type melt-spun spandex chips is 20-30 g / 10 min (200℃*2.16 kg), and the hardness is 82-84A.

[0059] Preferably, the reaction raw materials for the polyether-type melt-spun spandex chips include polytetrahydrofuran polyol, MDI, and 1,4-butanediol.

[0060] Preferably, the molecular weight of the polytetrahydrofuran polyol (PTMEG) is 1400-2100; the molar ratio of the polytetrahydrofuran polyol to 1,4-butanediol is 1:1.4 to 1:2.2.

[0061] The polytetrahydrofuran polyol (PTMEG) can be commercially available, such as PTMEG-1400, PTMEG-1800, PTMEG-1840, and PTMEG-2000 produced by manufacturers like BASF; it can also be a mixture of PTMEG with a molecular weight less than 1400 and PTMEG with a molecular weight greater than 1400, such as mixing PTMEG-1000 and PTMEG-2000 in a 1 / 2 molar ratio to obtain PTMEG with a molecular weight of 1500.

[0062] Preferably, the reaction raw materials for the polyester melt-spun spandex chips include polyester polyol, chain extender and isocyanate.

[0063] Preferably, the polyester polyol has a molecular weight of 3800-4500; the polyester polyol is obtained by reacting sebacic acid, 2-butyl-2-ethyl-1,3-propanediol and 1,6-hexanediol.

[0064] Preferably, the molar ratio of 2-butyl-2-ethyl-1,3-propanediol and 1,6-hexanediol is 1:1 to 1:2; the chain extender is 3-methyl-1,5-pentanediol; the isocyanate is MDI; and the molar ratio of the polyester polyol to the chain extender is 1:3.7 to 1:4.8.

[0065] Preferably, the raw materials also include one or more of antioxidants, UV stabilizers, carbodiimide anti-hydrolysis agents, titanium dioxide matting agents, and lubricants.

[0066] Preferably, by weight, the antioxidant is 0.5-1.5 parts, the carbodiimide anti-hydrolysis agent is 0.3-1.2 parts, the UV stabilizer is 0.5-1.2 parts, the lubricant is 0.0-1.0 parts (not zero), and the titanium dioxide matting agent is 0.0-2.0 parts. The antioxidant includes antioxidant 1010, antioxidant GA-80, antioxidant 168, antioxidant Revonox 420, Revonox 501, PDP, and antioxidant 626, etc.

[0067] The UV stabilizers include hindered amines, benzophenones, and benzotriazoles, such as light stabilizer 622, light stabilizer 770, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (HA-10), UV3030, UV903, UV-123, UV1, UV3, and UVT.

[0068] The lubricants include EBS, EBO, oleamide, modified EBS, stearic acid, calcium stearate, zinc stearate, magnesium stearate, etc.

[0069] The second objective of this invention is to provide a method for preparing the above-mentioned low-temperature spandex blended and shaped with PLA fibers, comprising the following steps:

[0070] The polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips are mixed and melt-plasticized to obtain a mixed melt.

[0071] The spinning oil and NCO-terminated prepolymer are preheated to 100-120°C and mixed with the mixed melt to prepare a filamentous melt. The melt is then subjected to cooling, oiling, drawing, guiding and winding processes to obtain a spandex fiber filament cake.

[0072] The spandex fiber cake is cured to obtain the low-temperature spandex that is blended and shaped with PLA fiber.

[0073] Preferably, before mixing and melting the polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips, the method further includes drying the polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips to a moisture content of less than 0.03%.

[0074] Preferably, the curing temperature is 30°C and the humidity is 80%. The curing time is one week.

[0075] Preferably, the polyether-type melt-spun spandex chips and polyester-type melt-spun spandex chips are mixed and then melt-plasticized in a single-screw extruder; the single-screw extruder adopts a 7-stage temperature control, and the temperatures of stages 1 to 7 are 180℃, 190℃, 200℃, 210℃, 210℃, 200℃, and 200℃, respectively.

[0076] The present invention will be further described in detail below with reference to embodiments. It should be noted that any aspects of the present invention not described in detail are conventional practices in the art and are not the focus of the present invention.

[0077] The spinning oil used in this embodiment of the invention is DELION 342 (Takemoto Oils & Fats Co., Ltd., Japan); the antioxidants used are GA80, PDP, and Revonox 501; the UV stabilizers are HA-10 and UV3; the lubricant is EBS; and the hydrolysant is Rhein Chemicals. P.

[0078] The composition of the low-temperature spandex raw materials in Examples 1-6 and Comparative Examples 1-4 of this invention is shown in Table 1.

[0079] Table 1

[0080] The preparation of NCO-terminated prepolymer (crosslinking agent) and different polyether-type melt-spun spandex chips and polyester-type melt-spun spandex chips is as follows:

[0081] Preparation of polyether-type melt-spun spandex chips:

[0082] Mix 32.73% PTMEG-1000 and 65.47% PTMEG-2000 and preheat to 100°C, then add 0.75% GA80, 0.3% PDP, and 0.75% PTMEG-2000. P was used as component A; MDI preheated to 60℃ was used as component B; BDO ​​preheated to 60℃ was used as component C; the weight ratio of components A / B / C was controlled at 67.11 parts: 5.54 parts: 25.95 parts (PTMEG-1000, PTMEG-2000 and 1,4-butanediol molar ratio 0.5:0.5:1.4). Components A, B and C were injected into a twin-screw extruder using a filling machine. 0.2 parts of Revonox 501, 0.3 parts of HA-10, 0.5 parts of UV3, and 0.4 parts of EBS were added to the small feed port of the extruder to prepare polyether-type spandex chips ET-CHIP1 with a hardness of 82A, a minimum molecular weight (MI) of 20-30 g / 10 min (190℃ * 2.16 kg), a glass transition temperature of -56.3℃, and a melting point of 167.3℃. This product was labeled ET-CHIP1.

[0083] Preheat 98.20% PTMEG-1800 to 100-120℃, then add 0.75% GA80, 0.3% PDP, and 0.75% GA80. P is used as component A; MDI is preheated to 80℃ as component B; BDO ​​is preheated to 670℃ as component C; the weight ratio of components A / B / C is controlled at 67.39 parts: 5.96 parts: 25.25 parts (PTMEG-1800 and 1,4-butanediol molar ratio 1:1.8). Components A, B, and C are injected into a twin-screw extruder using a filling machine. 0.2 parts of Revonox 501, 0.3 parts of HA-10, 0.5 parts of UV3, and 0.4 parts of EBS are added to the small feed port of the extruder to prepare polyether-type spandex chips ET-CHIP2 with a hardness of 83A, a minimum viscosity (MI) of 20-30 g / 10 min (190℃ * 2.16 kg), a glass transition temperature of -59℃, and a melting point of 170.6℃.

[0084] Preheat 98.20% PTMEG-2000 to 100-120℃, then add 0.75% GA80, 0.3% PDP, and 0.75% GA80. P is used as component A; MDI is preheated to 60-80℃ as component B; BDO ​​is preheated to 60-70℃ as component C; the weight ratio of components A / B / C is controlled at 66.54 parts: 6.48 parts: 25.58 parts (PTMEG-2000 and 1,4-butanediol molar ratio 1:2.2). Components A, B, and C are injected into a twin-screw extruder using a filling machine. 0.2 parts of Revonox 501, 0.3 parts of HA-10, 0.5 parts of UV3, and 0.4 parts of EBS are added to the small feed port of the extruder to prepare polyether-type spandex chips ET-CHIP3 with a hardness of 84A, a minimum viscosity (MI) of 20-30 g / 10 min (190℃ * 2.16 kg), a glass transition temperature of -61.5℃, and a melting point of 174.6℃.

[0085] Polyester melt-spun spandex chips:

[0086] The molar ratio of 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol, and sebacic acid was controlled at 6.21:9.32:14.25. A macromolecular polyester polyol with a molecular weight of 4000 was prepared first using sebacic acid, 2-butyl-2-ethyl-1,3-propanediol, and 1,6-hexanediol. 98.13% of the macromolecular polyol was preheated to 100-120℃, and then 0.43% GA80, 0.29% PDP, and 1.15% [other ingredients] were added. P is used as component A; MDI is preheated to 60-80℃ as component B; 3-methyl-1,5-pentanediol is preheated to 60-70℃ as component C; the weight ratio of components A / B / C is controlled at 69.44 parts: 8.05 parts: 21.21 parts (molar ratio of macromolecular polyol and 1,4-butanediol 1:4.0). Components A, B, and C are injected into a twin-screw extruder using a filling machine. 0.1 parts of Revonox 501, 0.3 parts of HA-10, 0.5 parts of UV3, and 0.4 parts of EBS are added to the small feed port of the extruder to prepare polyester-type spandex chips ES-CHIP1 with a hardness of 82A, a minimum molecular weight (MI) of 20-30 g / 10 min (200℃ * 2.16 kg), a glass transition temperature of -44.6℃, and a melting point of 113.6℃. These chips are labeled as ES-CHIP1.

[0087] The molar ratio of 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol, and sebacic acid was controlled at 6.93:10.40:16.08. A macromolecular polyester polyol with a molecular weight of 4500 was prepared first using sebacic acid, 2-butyl-2-ethyl-1,3-propanediol, and 1,6-hexanediol. 98.13% of the macromolecular polyol was preheated to 100-120℃, and 0.43% GA80, 0.29% PDP, and 1.15%... P is used as component A; MDI is preheated to 60-80℃ as component B; 3-methyl-1,5-pentanediol is preheated to 60-70℃ as component C; the weight ratio of components A / B / C is controlled at 69.79 parts: 8.09 parts: 20.82 parts (molar ratio of macromolecular polyol and 1,4-butanediol 1:4.5). Components A, B, and C are injected into a twin-screw extruder using a filling machine. 0.1 parts of Revonox 501, 0.3 parts of HA-10, 0.5 parts of UV3, and 0.4 parts of EBS are added to the small feed port of the extruder to prepare polyester-type spandex chips ES-CHIP2 with a hardness of 84A, a minimum molecular weight (MI) of 20-30 g / 10 min (200℃ * 2.16 kg), a glass transition temperature of -47.5℃, and a melting point of 118.1℃, labeled as ES-CHIP2.

[0088] Preparation of NCO-terminated prepolymers:

[0089] First, the molar ratio of castor oil to MDI-50 was controlled at 1:5, and the reaction was carried out at 80℃ for 3 hours to evaporate excess MDI-50. Then, N,N'-di-tert-butylethylenediamine equivalent to 0.5 times the molar amount of castor oil was added, and the reaction was continued at 80℃ for 3 hours to obtain prepolymer PRE1 with an NCO content of 4.5% to 4.8%.

[0090] The preparation steps of low-temperature spandex in Examples 1-6 and Comparative Examples 1-4 of this invention are as follows:

[0091] Polyether-type melt-spun spandex chips and polyester-type melt-spun spandex chips were dried with nitrogen gas until the moisture content was below 0.03%.

[0092] The two selected chips were metered by a loss-in-weight pump and injected into a single-screw extruder according to the ratio to obtain a homogeneous melt. The temperatures of the screw extruder sections 1 to 7 were 180℃, 190℃, 200℃, 210℃, 210℃, 200℃, and 200℃, respectively.

[0093] The melt is pressurized by a melt pump and then filtered through a filter screen to obtain a refined melt.

[0094] Part of the spinning oil agent 1 and crosslinking agent are preheated to 120°C, mixed evenly, and metered together with the refined melt by a metering pump and fed into a static mixer (SH type, including 32 sections);

[0095] After the slicing melt, spinning oil and crosslinking agent are mixed evenly in a static mixer, gel impurities are removed by a filter screen and the fine filament melt is sprayed out through a spinneret. It is then cooled by an annular blower, oiled with the remaining spinning oil 2, and then processed through traction, guiding and winding processes to obtain 30D spandex fiber filament cake.

[0096] The spandex filament cake is cured for one week at a temperature of 30°C and a humidity of 80% to obtain the finished low-temperature spandex.

[0097] Performance tests were conducted on the low-temperature spandex fibers of Examples 1-6 and Comparative Examples 1-4:

[0098] The 300% elastic recovery rate and mechanical properties of low-temperature spandex were tested in accordance with "FZ / T 54010 Spandex Filament".

[0099] Low-temperature spandex and cotton fiber are woven into high-elastic fabric using a circular knitting machine. A small-scale shaping machine is used to set the shaping temperature at 120℃, 130℃, and 140℃ for shaping tests.

[0100] Low-temperature spandex and PLA fibers were machine-packaged to verify the pull ratio.

[0101] Set the liquor ratio to 1:20, the dyeing pH to 4.5, add 10% spandex and 90% PLA fiber for dyeing, the heating rate to 1℃ / min, the dyeing temperature to 110℃, and the dyeing time to 45min.

[0102] The test results are shown in Table 2.

[0103] Table 2

[0104]

[0105] It can be seen that in Comparative Example 3, where the proportion of polyether-type melt-spun spandex chips reaches 46.9 parts, no web formation occurs during setting at 120–130℃; in Comparative Example 1, which uses pure polyether-type melt-spun spandex chips, no web formation occurs during setting at 120–140℃; in Comparative Example 2, which uses pure polyester-type melt-spun spandex chips, elasticity is lost when the setting temperature reaches 130℃, and color bleeding occurs during dyeing; in Comparative Example 4, which uses a different crosslinking agent, elasticity is lost when set at 140℃, and the 300% elastic recovery rate of the spandex is less than 90%. The technical solution of this invention produces spandex with a breaking strength of over 1.2 cN / detx, a breaking elongation of over 550%, a strength of over 0.23 cN / detx at 300% elongation, an elastic recovery rate of over 90% at 300% elongation, a draw ratio of over 3.0, and web formation during setting at 120-140℃. It also allows for easy cutting and arbitrarily trimming, and provides good dyeing results without color bleeding.

[0106] Figure 1 The images show the unraveling effect of the high-elastic fabrics woven in Example 2 and Comparative Example 3 after setting at 140°C. It can be seen that the web formation in Example 2 is obvious, while a complete web cannot be unraveled in Comparative Example 3.

[0107] Figure 2 The results are those of Example 2 and Comparative Example 2 after dyeing. In Example 2, the dyeing rate was 94.7%, and in Comparative Example 2, the dyeing rate was 61.1%. In Example 2, PLA and spandex had almost no color difference and the dyeing was uniform. In Comparative Example 2, PLA was lightly dyed, and the spandex stole the color.

[0108] Figure 3 The image shows the unraveling effect of the high-elastic fabric woven in Example 8 of the present invention after setting at 140°C. It can be seen that Example 8 can produce a perfect net.

[0109] Figure 4 These are the DSC spectra of the five types of slices used in this invention.

[0110] In summary, the low-temperature spandex blended and shaped with PLA fiber according to this invention can achieve arbitrary cutting effect when shaped within a temperature range of 120-140℃, and can be blended and dyed with PLA fiber, achieving the effect of dyeing without overpowering the color.

[0111] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low-temperature spandex blended and shaped with PLA fiber, characterized in that, By weight, the raw materials include the following components: 15-30 parts of polyether-type melt-spun spandex chips, 60-80 parts of polyester-type melt-spun spandex chips, 3.5-7.5 parts of NCO-terminated prepolymer, and 1-2 parts of spinning oil; The DSC melting point of the polyether-type melt-spun spandex chips is 165-175℃, and the glass transition temperature is -65℃ to -55℃. The DSC melting point of the polyester melt-spun spandex chips is 110-120℃, and the glass transition temperature is -50℃ to -40℃. The terminal NCO prepolymer is obtained by reacting castor oil, N,N'-di-tert-butylethylenediamine and MDI-50, with an NCO content of 4.5% to 4.8%.

2. The low-temperature spandex according to claim 1, characterized in that, The melt of the polyether-type melt-spun spandex chips has an MI of 20-30 g / 10 min and a hardness of 82-84 A under conditions of 190°C and 2.16 kg; the melt of the polyester-type melt-spun spandex chips has an MI of 20-30 g / 10 min and a hardness of 82-84 A under conditions of 190°C and 2.16 kg.

3. The low-temperature spandex according to claim 1, characterized in that, The reaction raw materials for the polyether-type melt-spun spandex chips include polytetrahydrofuran polyol, MDI and 1,4-butanediol; the molecular weight of the polytetrahydrofuran polyol is 1400-2100; the molar ratio of the polytetrahydrofuran polyol to 1,4-butanediol is 1:1.4 to 1:2.

2.

4. The low-temperature spandex according to claim 1, characterized in that, The reaction raw materials for the polyester melt-spun spandex chips include polyester polyol, chain extender and MDI; the molar ratio of polyester polyol and chain extender is 1:3.7 to 1:4.

8.

5. The low-temperature spandex according to claim 4, characterized in that, The chain extender is 3-methyl-1,5-pentanediol.

6. The low-temperature spandex according to claim 4, characterized in that, The polyester polyol has a molecular weight of 3800-4500; the polyester polyol is obtained by reacting sebacic acid, 2-butyl-2-ethyl-1,3-propanediol and 1,6-hexanediol.

7. The low-temperature spandex according to claim 1, characterized in that, The raw materials also include one or more of the following: antioxidants, UV stabilizers, carbodiimide anti-hydrolysis agents, titanium dioxide matting agents, and lubricants.

8. The low-temperature spandex according to claim 7, characterized in that, Based on mass parts, the antioxidant is 0.5 to 1.5 parts, the carbodiimide anti-hydrolysis agent is 0.3 to 1.2 parts, the UV stabilizer is 0.5 to 1.2 parts, the lubricant is 0.0 to 1.0 parts, and not 0, and the titanium dioxide matting agent is 0.0 to 2.0 parts.

9. The method for preparing low-temperature spandex blended and shaped with PLA fiber as described in claim 1, characterized in that, Includes the following steps: The polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips are mixed and melt-plasticized to obtain a mixed melt. The spinning oil and the NCO-terminated prepolymer are mixed with the mixed melt to prepare a filamentous melt, which is then subjected to cooling, oiling, drawing, guiding and winding processes to obtain a spandex fiber filament cake. The spandex fiber cake is cured to obtain the low-temperature spandex that is blended and shaped with PLA fiber.

10. The preparation method according to claim 9, characterized in that, The polyether-type melt-spun spandex chips and the polyester-type melt-spun spandex chips are mixed and then melt-plasticized in a single-screw extruder. The single-screw extruder uses a 7-stage temperature control, with the temperatures of stages 1 to 7 being 180℃, 190℃, 200℃, 210℃, 210℃, 200℃, and 200℃, respectively.

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