A kind of spandex fiber with high elongation and high breaking strength and preparation method thereof

Abstract

The invention discloses a spandex fiber with high elongation and high breaking strength, wherein the main raw materials of the spandex fiber include polytetrahydrofuran diol, terminal hydroxyl polybutadiene, diisocyanate compound, chain extender and end capping agent. Its preparation method is to prepare spandex fiber by compounding terminal hydroxyl polybutadiene (THPB) with a molecular weight of 4000-10000 and polytetrahydrofuran (PTMEG) with a molecular weight of 2000-3000 as mixed diols, wherein the mass of THPB accounts for 3-7% of the mass of the mixed diols. The spandex fiber prepared by the method of the present invention has higher breaking strength and elongation at break, and its elongation at break is greater than 600%, and the breaking strength is greater than 55cN. The present invention prepares spandex fiber and also has good chlorine resistance, acid resistance and alkali resistance. After soaking in sodium hypochlorite, acid and alkaline solution for 24h, the breaking strength retention rate of the fiber is higher than 90%.

Description

Technical Field

[0001] The invention belongs to the field of chemical materials and textile fibers, and relates to a spandex fiber with high elongation and high breaking strength and a preparation method thereof. Background Art

[0002] Spandex, commonly known as Spandex internationally, is also known as polyurethane elastic fiber. It is a highly elastic fiber that was industrially produced in the 1950s. With the improvement of production technology and the promotion of application technology, the production and consumption of spandex have been strongly promoted, especially in recent years, which has ushered in the rapid development of spandex fiber production and consumption.

[0003] Spandex is the trade name of polyurethane elastic fiber. The macromolecular chain segments of polyurethane fiber contain polyurethane. The fiber has an amorphous structure and a low glass transition temperature. At room temperature, the flexible chain segments of the macromolecules are in a highly elastic state. This structural feature makes the fiber have great extensibility at standard temperature and humidity, and the maximum elongation can reach 400-800%.

[0004] If polyurethane is made into a homopolymer, the fiber is the same as ordinary fiber and has no elasticity. Spandex is a fiber made by block copolymerization. Its molecular structure contains both soft, non-crystalline low-molecular segments, such as polyester and polyether segments, and hard rigid segments, such as diisocyanate, which is crystalline and can produce transverse cross-linking. These two segments with different properties are connected in an inlaid manner, and the flexible segments have certain cross-linking to form a network structure. When the fiber is subjected to external force, the flexible segments are easily stretched and deformed due to the small interaction force between the molecular chains. This is the reason why spandex is easy to be stretched. On the other hand, due to the presence of rigid segments, the molecules will not slip when subjected to external forces, which gives it sufficient resilience. Furthermore, because a certain network structure is formed between the flexible segments, this structure allows the molecules to always maintain a certain relative position. Even if it is stretched tens of thousands of times, it can still have resilience like a rubber band.

[0005] The length of the soft segment molecular chain is longer than that of the hard segment, and the soft segment contains more hydrocarbon structures, which makes the soft segment in an amorphous state at room temperature. The chemical regularity of the soft segment phase, the main valence force of the macromolecular chain, the force between molecules and the flexibility of the macromolecular chain have a great influence on the low temperature resistance, crystallinity, mechanical properties, melting point and flexibility of polyurethane elastomers.

[0006] The influence of the soft segment on polyurethane elastomers or fibers is mainly manifested in: the type of soft segment, molecular weight (hydroxyl value) and functionality. Elastomers with polyester polyol as the soft segment have good heat resistance, relatively good tensile strength, tear strength, oil resistance and wear resistance. Elastomers with polyether polyol as the soft segment have good hydrolysis resistance, low soft segment glass transition temperature and good mildew resistance, but poor mechanical properties.

[0007] Polyols provide soft chain ends for polyurethane elastomers, and their physical properties are flexibility. Polyols in polyurethane elastomers are generally oligomer polyols, with functionalities of 2-3 and molecular weights of 400-6000, with 1000-3000 being the most commonly used. The lower the molecular weight of the soft segment, the higher the relative content of the hard segment.

[0008] Unlike the hard segment structure which mainly determines the rebound recovery rate of spandex fiber, the soft segment structure mainly determines the elongation and breaking strength of spandex fiber. The polyurethane soft segment is generally composed of oligomer polyols.

[0009] At present, most oligomer polyols mainly include polyester polyols and polyether polyols. The soft segment content in polyurethane elastomers is relatively large, and generally forms soft segment crystals, and the glass transition temperature is lower than room temperature. Common polyether polyols for preparing spandex fibers include polytetramethylene glycol (PTMEG), polypropylene oxide (PPG), poly-1,3-propylene glycol, and other copolyether diols. Common polyester polyols for preparing spandex fibers include polybutylene succinate (PBS), polycaprolactone (PCL), polyhexane adipate, and other copolyester diols.

[0010] The elongation of spandex fibers prepared from polyether and polyester diols is generally between 300% and 500%. At the same time, the breaking strength of the spandex fibers prepared is relatively low. For example, the breaking strength of spandex with a fiber fineness of 20D is often below 30cN.

[0011] In order to obtain spandex fibers with high elongation, the method adopted in patent CN201611046662.8 is to use a mixed diamine of fatty amine and polyether amine as a chain extender during chain extension. However, the use of polyether amine as a chain extender may reduce the content of diisocyanate as a hard segment component. Although the elongation of the prepared spandex fiber is improved, the acid and alkali resistance of the spandex fiber is poor; the method adopted in CN202110212692.6 is to use high molecular weight PTMEG instead of the common PTMEG with a molecular weight of 1800 to produce spandex. The fiber uses a molecular weight of PTMEG between 2300 and 28000, and PTMEG with a molecular weight of 28000 is expensive and extremely difficult to obtain; Patent CN202310035659.X introduces a method for preparing melt-spinning spandex with high elongation at break and high bio-based content, which uses polyester diols obtained by polycondensation of bio-based 1,3-propylene glycol and cyclohexanedimethanol, or neopentyl glycol and undecanediol to prepare spandex, and its spinning process is melt spinning, rather than the common solution dry spinning. In addition, the spandex fiber prepared by this method has a low breaking strength. Therefore, how to obtain a spandex fiber with high elongation, high breaking strength and strong acid and alkali resistance has become the current research focus. Summary of the invention

[0012] In view of the above-mentioned problems, the present invention provides a spandex fiber with high elongation and high breaking strength and a preparation method thereof, wherein terminal hydroxyl polybutadiene (abbreviated as hydroxybutyl, HTPB, with the structural formula as follows) is used as a modifier, compounded with common polytetrahydrofuran (PTMEG), and the spandex fiber is prepared by solution dry spinning, so as to solve the problems of low elongation, low breaking strength and poor acid and alkali resistance of spandex fiber in the prior art.

[0013] The invention firstly provides a spandex fiber with high elongation and high breaking strength. The main raw materials of the spandex fiber include polytetramethylene glycol (PTMEG), hydroxyl-terminated polybutadiene (HTPB), a diisocyanate compound, a chain extender and a capping agent.

[0014] The present invention adopts terminal hydroxyl polybutadiene (abbreviated as hydroxybutadiene, HTPB, with the structural formula as follows) as a modifier, and mixes it with common polytetramethylene glycol (PTMEG) to prepare spandex fiber together, so as to improve the elongation and breaking strength of the spandex fiber.

[0015]

[0016] Hydroxyl-terminated polybutadiene (HTPB) structure

[0017] Hydroxyl-terminated polybutadiene (HTPB) itself is a very important translucent liquid rubber, and its molecular weight is generally between 2000 and 10000 g / mol. HTPB is often used in the preparation and production of cast elastomers, general rubber products, thermal insulation materials, adhesives, coatings, injection materials, waterproof and anti-corrosion materials, insulation materials, building materials and epoxy resin modification. HTPB has the advantages of good transparency, low viscosity, low temperature performance and good processing performance. At the same time, HTPB does not contain the ether bonds and ester bonds of ordinary polyester and polyether spandex fibers, so the prepared spandex fibers have the characteristics of hydrolysis stability, chlorine bleaching resistance, oil resistance, and good aging resistance.

[0018] In one embodiment of the present invention, the polytetrahydrofuran diol (PTMEG) is polytetrahydrofuran (PTMG) with a molecular weight of 1800-3000, preferably 2000-3000, and a hydroxyl value of 37.39-56.1 mgKOH / g, and its structure is as follows:

[0019]

[0020] Where n represents the degree of polymerization of PTMG, which is a natural number between 28 and 42.

[0021] In one embodiment of the present invention, the molecular weight of the hydroxyl-terminated polybutadiene (HTPB) is between 4000 and 10000, the hydroxyl value is 11.22 to 28.05 mgKOH / g, and the structural formula is as follows:

[0022]

[0023] In one embodiment of the present invention, the mass of the hydroxyl-terminated polybutadiene (HTPB) is 3-7% of the total mass of polytetramethylene glycol (PTMEG) and the hydroxyl-terminated polybutadiene (HTPB).

[0024] In one embodiment of the present invention, the diisocyanate compound is diphenylmethane diisocyanate (MDI) and / or toluene diisocyanate (TDI).

[0025] In one embodiment of the present invention, the ratio of the molar amount of the diisocyanate compound to the total molar amount of polytetramethylene glycol (PTMEG) and hydroxy-terminated polybutadiene (HTPB) is (2-2.02):1.

[0026] In one embodiment of the present invention, the chain extender is 1,4-cyclohexanediamine and / or ethylenediamine.

[0027] In one embodiment of the present invention, the ratio of the molar amount of the chain extender to the total molar amount of polytetramethylene glycol (PTMEG) and hydroxy-terminated polybutadiene (HTPB) is 0.9:1 to 1.1:1.

[0028] In one embodiment of the present invention, the capping agent is diethylamine and / or n-butylamine.

[0029] In one embodiment of the present invention, the ratio of the molar amount of the end-capping agent to the total molar amount of polytetramethylene glycol (PTMEG) and hydroxy-terminated polybutadiene (HTPB) is (0.1-0.15):1.

[0030] The present invention also discloses a method for preparing the above-mentioned spandex fiber with high elongation and high breaking strength, comprising the following steps:

[0031] (1) Prepolymerization: Mix the mixed diol of HTPB and PTMEG with an organic solvent to prepare a mixed solution, add a diisocyanate compound to the mixed solution while stirring, and prepolymerize at 40-45° C. for 3-6 hours to obtain a polyurethane prepolymer solution;

[0032] (2) Chain extension: adding a chain extender to the polyurethane prepolymer solution obtained in step (1), and carrying out a chain extension reaction at 40-45° C. for 2-3 hours;

[0033] (3) Capping: adding a capping agent to the mixed solution after chain extension in step (2), and capping at 40-45° C. for 2-3 hours to obtain a polyurethane solution;

[0034] (4) Ripening: Ripening the polyurethane solution obtained in step (3) at 37-45° C. with continuous stirring for 28-30 hours;

[0035] (5) Spinning: The spinning solution matured in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers.

[0036] In one embodiment of the present invention, in the mixed solution of step (1), the mass concentration of the mixed diol of HTPB and PTMEG is 20-40%.

[0037] In one embodiment of the present invention, the organic solvent in step (1) is N,N-dimethylacetamide.

[0038] In one embodiment of the present invention, in the mixed diol of HTPB and PTMEG in step (1), the mass ratio of HTPB to the mixed diol is 3-7%;

[0039] In one embodiment of the present invention, the molecular weight of HTPB is between 4000-10000, and the molecular weight of PTMEG is between 1800-2500.

[0040] Beneficial effects of the present invention:

[0041] 1. The present invention adopts HTPB and PTMEG compound as soft segments to prepare spandex fibers, thereby improving elongation and breaking strength. The spandex fibers prepared by the present invention have elongation at break greater than 600% and breaking strength greater than 55 cN.

[0042] 2. By adding HTPB to polytetrahydrofuran diol, the hydrolysis stability and chlorine bleaching resistance, oil resistance and aging resistance of the spandex fiber are improved. After the spandex fiber prepared by the present invention is immersed in sodium hypochlorite, acid and alkaline solutions for 24 hours, the fiber's breaking strength retention rate is higher than 90%. DETAILED DESCRIPTION

[0043] The following examples are provided to further illustrate the present invention, but the present invention is not limited thereto.

[0044] Example 1

[0045] A method for preparing a spandex fiber with high elongation and high breaking strength comprises the following steps:

[0046] (1) Prepolymerization: In a reaction kettle filled with 500 kg of N,N-dimethylacetamide (DMAc), 194 kg of PTMEG (polytetrahydrofuran, molecular weight 2000, hydroxyl value 56.1 mgKOH / g, produced by Shanxi Sanwei Group) and 6 kg of HTPB (hydroxy-terminated polybutadiene, molecular weight 10000, hydroxyl value 11.22 mgKOH / g, produced by EVONIK) were added, and then 48.8 kg of diphenylmethane diisocyanate (produced by BASF Chemical) was added while stirring, and prepolymerization was carried out at 40°C for 3 hours;

[0047] (2) Chain extension: 11.14 kg of chain extender 1,4-cyclohexanediamine (produced by Sinopharm Group) was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 2 hours;

[0048] (3) End-capping: 0.3 kg of end-capping agent diethylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 40° C. for 2 hours.

[0049] (4) Ripening: The polyurethane solution prepared in step (3) was stirred continuously at 45° C. for 28 hours for aging, and the system viscosity was measured to be 4200 poise.

[0050] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, numbered 1#.

[0051] Example 2

[0052] A method for preparing a spandex fiber with high elongation and high breaking strength comprises the following steps:

[0053] (1) Prepolymerization: In a reaction kettle charged with 700 kg of N,N-dimethylacetamide (DMAc), 190 kg of PTMEG (polytetrahydrofuran, molecular weight 2300, hydroxyl value 48.78 mgKOH / g, produced by Shanxi Sanwei Group) and 10 kg of HTPB (hydroxy-terminated polybutadiene, molecular weight 4000, hydroxyl value 28.05 mgKOH / g, produced by EVONIK) were added, and then 42.55 kg of diphenylmethane diisocyanate (produced by BASF Chemical) was added while stirring, and prepolymerization was carried out at 40° C. for 3 hours;

[0054] (2) Chain extension: 5.1 kg of chain extender ethylenediamine was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 2 hours;

[0055] (3) End-capping: 3.1 kg of end-capping agent n-butylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 40° C. for 2 hours.

[0056] (4) Ripening: The polyurethane solution prepared in step (3) was matured by continuous stirring at 45° C. for 28 hours. The system viscosity was measured to be 5020 poise.

[0057] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, numbered 2#.

[0058] Example 3

[0059] A method for preparing a spandex fiber with high elongation and high breaking strength comprises the following steps:

[0060] (1) Prepolymerization: 398 kg PTMEG (molecular weight 3000, hydroxyl value 37.39 mgKOH / g) and 30 kg HTPB (hydroxyl-terminated polybutadiene, molecular weight 6000, hydroxyl value 18.7 mgKOH / g, produced by EVONIK) were added to a reactor containing 1000 kg DMAc, and then toluene diisocyanate was added while stirring. T65N (a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, produced by Covestro) 47.9 kg, prepolymerized at 44 ° C for 6 hours;

[0061] (2) Chain extension: Add 7.85 kg of a mixture of 1,4-cyclohexanediamine and 4.13 kg of ethylenediamine to the reactor of step (1), and perform a chain extension reaction on the prepolymer prepared in step (1) at 45° C. for 2 hours;

[0062] (3) End-capping: 3.1 kg of end-capping agent n-butylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 45° C. for 2 hours.

[0063] (4) Ripening: The bio-based polyurethane solution prepared in step (3) was matured by continuous stirring at 40° C. for 28 hours. The system viscosity was measured to be 5500 poise.

[0064] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, numbered 3#.

[0065] Example 4

[0066] A method for preparing a spandex fiber with high elongation and high breaking strength comprises the following steps:

[0067] (1) Prepolymerization: In a reactor containing 700 kg of N,N-dimethylacetamide (DMAc), 380 kg of PTMEG (polytetrahydrofuran, molecular weight 2500, hydroxyl value 44.88 mgKOH / g, produced by Shanxi Sanwei Group) and 20 kg of HTPB (hydroxy-terminated polybutadiene, molecular weight 6000, hydroxyl value 18.7 mgKOH / g, produced by EVONIK) were added, and then toluene diisocyanate was added while stirring. T65N (a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, produced by Covestro) 54.1 kg, prepolymerized at 40°C for 3 hours;

[0068] (2) Chain extension: 17.7 kg of chain extender 1,4-cyclohexanediamine was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 2 hours;

[0069] (3) End-capping: 0.5 kg of end-capping agent diethylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 40° C. for 2 hours.

[0070] (4) Ripening: The polyurethane solution prepared in step (3) was matured by continuous stirring at 45° C. for 28 hours. The system viscosity was measured to be 6050 poise.

[0071] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, numbered 4#.

[0072] Example 5

[0073] A method for preparing a spandex fiber with high elongation and high breaking strength comprises the following steps:

[0074] (1) Prepolymerization: In a reactor containing 1000 kg of DMAc, 518.4 kg of PTMEG (molecular weight 2300, hydroxyl value 48.78 mgKOH / g) and 21.6 kg of HTPB (molecular weight 8000, 14.02 mgKOH / g) were added, and then toluene diisocyanate was added while stirring. T65N 79.38kg, prepolymerized at 44°C for 6 hours;

[0075] (2) Chain extension: 13 kg of chain extender 1,4-cyclohexanediamine and 6.8 kg of chain extender ethylenediamine were added to the reaction kettle to carry out chain extension reaction on the prepolymer prepared in step (1) at 45° C. for 2.3 hours;

[0076] (3) End-capping: 0.5 kg of end-capping agent n-butylamine and 0.1 kg of end-capping agent diethylamine were added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 45° C. for 3 hours.

[0077] (4) Ripening: The bio-based polyurethane solution prepared in step (3) was matured by continuous stirring at 40° C. for 28 hours. The measured system viscosity was 6100 poise.

[0078] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, numbered 5#.

[0079] Example 6

[0080] A method for preparing a spandex fiber with high elongation and high breaking strength comprises the following steps:

[0081] (1) Prepolymerization: In a reactor containing 1000 kg of DMAc, 502.2 kg of PTMEG (molecular weight 2300, hydroxyl value 48.78 mg KOH / g) and 37.8 kg of HTPB (molecular weight 8000, 14.02 mg KOH / g) were added, and then toluene diisocyanate was added while stirring. T65N 76.22kg, prepolymerized at 40°C for 5 hours;

[0082] (2) Chain extension: 13.1 kg of chain extender ethylenediamine was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 1 hour;

[0083] (3) End-capping: 1.4 kg of end-capping agent n-butylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 45° C. for 2 hours.

[0084] (4) Ripening: The bio-based polyurethane solution prepared in step (3) was matured by continuous stirring at 40° C. for 28 hours. The measured system viscosity was 6220 poise.

[0085] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, numbered 6#.

[0086] Comparative Example 1

[0087] The difference between Comparative Example 1 and Example 1 is that in step (1), no HTPB is added and the mass of the added PTMEG is 200 kg.

[0088] A method for preparing spandex fiber comprises the following steps:

[0089] (1) Prepolymerization: In a reaction kettle filled with 700 kg of N,N-dimethylacetamide (DMAc), 200 kg of PTMEG (molecular weight 2300, hydroxyl value 48.78 mgKOH / g) was added, and then 43.48 kg of diphenylmethane diisocyanate (produced by BASF Chemical) was added while stirring, and prepolymerization was carried out at 40°C for 3 hours;

[0090] (2) Chain extension: 5.22 kg of chain extender ethylenediamine was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 2 hours;

[0091] (3) End-capping: 3.0 kg of end-capping agent n-butylamine was added to end-cap the polymer prepared in step (2) at 40° C. for 2 hours.

[0092] (4) Ripening: The polyurethane solution prepared in step (3) was matured by continuous stirring at 45° C. for 28 hours. The system viscosity was measured to be 4200 poise.

[0093] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, which are numbered as comparative sample 1#.

[0094] Comparative Example 2

[0095] The difference between Comparative Example 2 and Example 6 is that in step (1), no HTPB is added and the mass of the added PTMEG is 540 kg.

[0096] A method for preparing spandex fiber comprises the following steps:

[0097] (1) Prepolymerization: In a reactor containing 1000 kg of DMAc, 540 kg of PTMEG (molecular weight 2300, hydroxyl value 48.78 mg KOH / g) was added, and then toluene diisocyanate was added while stirring. T65N 81.7kg, prepolymerized at 40°C for 5 hours;

[0098] (2) Chain extension: 14.1 kg of chain extender ethylenediamine was added to the reaction kettle of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 1 hour;

[0099] (3) End-capping: 1.4 kg of end-capping agent n-butylamine was added to end-cap the polymer prepared in step (2) at 45° C. for 2 hours.

[0100] (4) Ripening: The bio-based polyurethane solution prepared in step (3) was matured by continuous stirring at 40° C. for 28 hours. The measured system viscosity was 6220 poise.

[0101] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, which are numbered as comparative sample 2#.

[0102] Comparative Example 3

[0103] The difference between Comparative Example 3 and Example 6 is that in step (1), the molecular weight of the added HTPB is 2000, and the added amount is still 37.8 kg.

[0104] A method for preparing spandex fiber comprises the following steps:

[0105] (1) Prepolymerization: In a reactor containing 1000 kg of DMAc, 502.2 kg of PTMEG (molecular weight 2300, hydroxyl value 48.78 mg KOH / g) and 37.8 kg of HTPB (molecular weight 2000, hydroxyl value 56.1 mg KOH / g) were added, and then toluene diisocyanate was added while stirring. T65N 78.76kg, prepolymerized at 40°C for 5 hours;

[0106] (2) Chain extension: 13.6 kg of chain extender ethylenediamine was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 1 hour;

[0107] (3) End-capping: 1.4 kg of end-capping agent n-butylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 45° C. for 2 hours.

[0108] (4) Ripening: The bio-based polyurethane solution prepared in step (3) was matured by continuous stirring at 40° C. for 28 hours. The system viscosity was measured to be 3720 poise.

[0109] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, which are numbered as comparative sample 3#.

[0110] Comparative Example 4

[0111] The difference between Comparative Example 4 and Example 6 is that in step (1), the molecular weight of the added HTPB is 8000 and the added amount is 38.00 kg.

[0112] (1) Prepolymerization: In a reactor containing 1000 kg of DMAc, 502.2 kg of PTMEG (molecular weight 2300, hydroxyl value 48.78 mg KOH / g) and 38.00 kg of HTPB (molecular weight 8000, hydroxyl value 14.03 mg KOH / g) were added, and then toluene diisocyanate was added while stirring. T65N 76.22kg, prepolymerized at 40°C for 5 hours;

[0113] (2) Chain extension: 13.1 kg of chain extender ethylenediamine was added to the reactor of step (1) to carry out chain extension reaction on the prepolymer prepared in step (1) at 40° C. for 1 hour;

[0114] (3) End-capping: 1.4 kg of end-capping agent n-butylamine was added to the mixture after chain extension in step (2) to end-cap the polymer prepared in step (2) at 45° C. for 2 hours.

[0115] (4) Ripening: The bio-based polyurethane solution prepared in step (3) was matured by continuous stirring at 40° C. for 28 hours. The system viscosity was measured to be 4220 poise.

[0116] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers, which are numbered as comparative sample 4#.

[0117] High elongation and high breaking strength spandex fiber performance test

[0118] The spandex fiber samples prepared in the examples and comparative examples were tested according to standards FZ / T 50006-2013 (test method for tensile properties of spandex fibers) and FZ / T 50007-2012 (test method for elasticity of spandex yarns).

[0119] The chlorine resistance test of spandex fiber is carried out in accordance with standard FZ / T 50034-2016 (test method for chlorine resistance of spandex filaments), and the sodium hypochlorite used for the test is prepared in accordance with standard FZ / T 50034-2016;

[0120] The acid resistance test of the fiber was carried out using the same equipment and test procedures as standard FZ / T 50034-2016, except that the acidic and alkaline solutions for fiber immersion treatment were prepared as shown in Table 1, and the breaking strength retention was tested and calculated according to the following method.

[0121] Table 1 Acid and alkali solution for spandex fiber acid and alkali resistance test

[0122] Reagents acidic solution Alkaline solution Sodium dihydrogen phosphate 5g Dilute hydrochloric acid (10%) 1 ml Dilute sulfuric acid 10% 0.2 ml Sodium carbonate 5g Sodium hydroxide 1 gram Deionized water 1000ml 1000ml

[0123] The fiber was treated in deionized water, sodium hypochlorite solution, acid solution and alkaline solution for 24 hours (room temperature 25°C), and then the strength of the fiber after treatment in the four solutions was measured. The fiber breaking strength retention rate was calculated according to the following formula (1):

[0124]

[0125] In formula (1):

[0126] A---Breaking strength retention rate;

[0127] F0---Fiber breaking strength after soaking in deionized water, unit is centinewton (cN);

[0128] F1---Fiber breaking strength after immersion in test solution, in centinewton (cN);

[0129] The mechanical property test results of the spandex fibers prepared in the examples and comparative examples are shown in Table 2. It can be seen from Table 2 that after adding THPB to PTMEG, the tensile elongation and breaking strength of the spandex fibers prepared are significantly improved, the tensile elongation is greater than 600%, and the breaking strength is greater than 55cN. For ordinary polyether-based spandex fibers, the breaking elongation strength of 20D spandex fibers does not exceed 25cN, and the breaking elongation is about 400%. When the molecular weight of the added THPB is less than 4000, the breaking strength of the spandex fibers prepared is also less than 25cN, and the breaking elongation is less than 300%.

[0130] Table 2 Mechanical properties test of spandex fiber

[0131]

[0132]

[0133] Table 3 shows the test results of the chlorine resistance, acid resistance and alkali resistance of the spandex fibers prepared in the examples and comparative examples. It can be seen from Table 3 that the spandex fibers prepared by mixing THPB and PTMEG have greatly improved chlorine bleaching resistance, acid resistance and alkali resistance, and the fiber breaking strength retention rate is higher than 90%.

[0134] Table 3 Mechanical properties test of spandex fiber

[0135]

[0136] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A spandex fiber with high elongation and high breaking strength, characterized in that: The main raw materials of the spandex fiber are composed of polytetramethylene glycol, terminal hydroxyl polybutadiene, diisocyanate compound, chain extender and end-capping agent.

2. The spandex fiber according to claim 1, characterized in that: Described polytetrahydrofuran diol is the polytetrahydrofuran of molecular weight 1800-3000, and its structure is as follows: Wherein, n represents the degree of polymerization of PTMG, which is a natural number ranging from 28 to 42.

3. The spandex fiber according to claim 1, characterized in that: The molecular weight of the hydroxy-terminated polybutadiene is between 4000 and 10000, the hydroxyl value is between 11.22 mg KOH / g and 28.05 mg KOH / g, and the structural formula is as follows:

4. The spandex fiber according to claim 1, characterized in that: The mass of the terminal hydroxyl polybutadiene is 3-7% of the total mass of the polytetrahydrofuran diol and the terminal hydroxyl polybutadiene.

5. The spandex fiber according to claim 1, characterized in that: The diisocyanate compound is diphenylmethane diisocyanate and / or toluene diisocyanate, and the ratio of the molar amount of the diisocyanate compound to the total molar amount of polytetrahydrofuran diol and terminal hydroxyl polybutadiene is (2-2.02):

1.

6. The spandex fiber according to claim 1, characterized in that: The chain extender is 1,4-cyclohexanediamine and / or ethylenediamine, and the ratio of the molar amount of the chain extender to the total molar amount of polytetrahydrofuran diol and terminal hydroxyl polybutadiene is 0.9:1-1.1:

1.

7. The spandex fiber according to claim 1, characterized in that: The end-capping agent is diethylamine and / or n-butylamine, and the ratio of the molar amount of the end-capping agent to the total molar amount of polytetrahydrofuran diol and terminal hydroxyl polybutadiene is (0.1-0.15):

1.

8. A method for preparing spandex fiber with high elongation and high breaking strength according to claims 1 to 7, characterized in that: The following steps are involved: (1) Prepolymerization: Mixing a mixed diol of terminal hydroxyl polybutadiene and polytetrahydrofuran diol with an organic solvent to prepare a mixed solution, adding a diisocyanate compound to the mixed solution while stirring, and prepolymerizing at 40-45° C. for 3-6 hours to obtain a polyurethane prepolymer solution; (2) Chain extension: adding a chain extender to the polyurethane prepolymer solution obtained in step (1), and carrying out a chain extension reaction at 40-45° C. for 2-3 hours; (3) Capping: adding a capping agent to the mixed solution after chain extension in step (2), and capping at 40-45° C. for 2-3 hours to obtain a polyurethane solution; (4) Ripening: Ripening the polyurethane solution obtained in step (3) at 37-45° C. with continuous stirring for 28-30 hours; (5) Spinning: The spinning solution matured in step (4) is spun through operations such as discharging, spraying, stretching, false twisting and oiling to produce spandex fibers.

9. The preparation method according to claim 8, characterized in that: In the mixed solution described in step (1), the mass concentration of the mixed diol of terminal hydroxyl polybutadiene and polytetrahydrofuran diol is 20-40%.

10. The preparation method according to claim 8, characterized in that: The molecular weight of the hydroxy-terminated polybutadiene is between 4000 and 10000, and the molecular weight of the polytetramethylene glycol is between 1800 and 2500.

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