Aliphatic spandex elastic fiber and preparation method thereof

Abstract

The invention discloses an aliphatic spandex elastic fiber and a preparation method thereof. By using an aliphatic diisocyanate, yellowing of the benzene ring structure of diphenylmethane diisocyanate in a conventional spandex formula is avoided, and the yellowing resistance of the spandex is greatly improved. By using a primary amine chain extender containing a sterically hindered group and simultaneously introducing a secondary amine chain extender containing a large steric hindrance, the steric hindrance of the spandex molecular chain is increased, the crystallization performance of the spandex is reduced, thereby solving the problem that the spandex spinning solution of the aliphatic isocyanate system is prone to gelling.

Description

Technical Field

[0001] The present invention relates to the field of dry-process spandex preparation, and in particular to an aliphatic spandex elastic fiber and a preparation method thereof. Background Art

[0002] Spandex fiber has excellent high elasticity. Adding a small amount of spandex can significantly increase the elasticity of the fabric. It is widely used in clothing such as swimwear and fitness wear, as well as in medical applications such as medical bandages. Traditional spandex is made from diphenylmethane diisocyanate, which contains a benzene ring structure. This results in poor yellowing resistance. It tends to yellow with prolonged storage or exposure to sunlight, especially in light-colored spandex products. This yellowing problem is particularly pronounced, significantly limiting spandex's application.

[0003] Patent CN101736432B provides a method for producing yellowing-resistant polyurethane elastic fibers, which uses 4,4-diphenylmethane diisocyanate and isophorone diisocyanate to polymerize with polyols to prepare polyurethane elastic fibers, reducing the tendency of the polymer to turn yellow due to the presence of unsaturated double bonds, ultraviolet radiation, and oxidation.

[0004] Patent CN110241473B provides a method for preparing spandex with long-lasting aging resistance. End-hydroxyl hydrogenated polybutadiene and norbornane diisocyanate are introduced into the polyurethane molecular chain in a certain proportion to prepare spandex fiber. The spandex prepared by this patented technology has excellent light stability, heat resistance, yellowing resistance, and weather resistance, extending the service life of spandex-containing fabrics.

[0005] Patent CN105401250B provides a reactive stabilizer for spandex that has the dual effects of an antioxidant and an anti-yellowing agent. 3,5-di-tert-butyl-4-hydroxyphenylpropionylhydrazide or 3-methyl-5-tert-butyl-4-hydroxyphenylpropionylhydrazide is added to spandex in a certain proportion. The use of the reactive stabilizer using this patented technology can significantly improve the spandex's anti-yellowing, NOx resistance, and heat resistance.

[0006] Although the above patents have improved the yellowing resistance of spandex to a certain extent, diphenylmethane diisocyanate still accounts for a large proportion in its formula, making it difficult to fundamentally solve the yellowing problem.

[0007] In the existing field of thermoplastic polyurethane elastomers, aliphatic isocyanates are used to achieve good yellowing resistance. However, in the spandex field, if aliphatic isocyanates are used directly to produce spandex, due to their relatively soft and regular molecular structure, when polymerized with traditional amine chain extenders, the synthesized molecular chains have strong crystallinity, resulting in a decrease in the solubility of the prepared spandex in solvents. The spandex spinning solution is prone to gelling, making it difficult to flow and hindering the spinning operation, which has seriously hindered the development of aliphatic spandex products. Summary of the Invention

[0008] In response to the above-mentioned technical problems and the shortcomings in the art, the present invention provides an aliphatic spandex elastic fiber, which uses aliphatic diisocyanates to avoid the yellowing of the benzene ring structure of diphenylmethane diisocyanate in conventional spandex formulas, thereby greatly improving the yellowing resistance of the spandex; by using a primary amine chain extender containing a sterically hindered group and simultaneously introducing a secondary amine chain extender containing a large steric hindrance, the steric hindrance of the spandex molecular chain is increased, and the crystallization performance of the spandex is reduced, thereby solving the problem that the spandex spinning solution of the aliphatic isocyanate system is prone to gelation.

[0009] An aliphatic spandex elastic fiber, the raw materials of which include aliphatic diol, aliphatic diisocyanate, a solvent, a secondary amine chain extender, a primary amine chain extender containing a sterically hindered group, and a terminator;

[0010] The mass ratio of aliphatic diol to aliphatic diisocyanate is 100:18-30;

[0011] The mass ratio of the prepolymer formed by the reaction of the aliphatic diol and the aliphatic diisocyanate to the solvent is 1:1 to 3;

[0012] Since the secondary amine chain extender contains large steric hindrance, when the secondary amine chain extender accounts for a large proportion, the mechanical properties of the spandex will be significantly reduced. If the secondary amine chain extender is not added, it will easily cause the spandex spinning solution to gel. Therefore, in order to solve the gel phenomenon of the spandex spinning solution while ensuring the mechanical properties of the spandex, the mass ratio of the secondary amine chain extender to the primary amine chain extender is 1 to 30:100, preferably 4 to 17:100;

[0013] In order to ensure that both the secondary amine chain extender and the primary amine chain extender can react with isocyanate and polymerize in the spandex molecular chain, the ratio of the total molar number of -NH- groups and -NH2 groups in the secondary amine chain extender and the primary amine chain extender to the molar number of isocyanate in the prepolymer formed by the reaction of the aliphatic diol and the aliphatic diisocyanate is 1:0.95-1.05. To obtain spandex with the best overall performance, the ratio is preferably 1:1.01-1.03.

[0014] The mass ratio of the primary amine chain extender to the terminator is 5 to 15:1;

[0015] The secondary amine chain extender is an addition reaction product of a primary diamine compound and diethyl maleate;

[0016] Secondary amine chain extenders prepared from different primary diamine compounds have different reactivity and also have a certain impact on the performance of spandex. In order to obtain a secondary amine chain extender with moderate reactivity and excellent spandex performance, the primary diamine compound includes at least one of propylene diamine, hexamethylene diamine, pentamethylene diamine, 1,4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

[0017] The primary diamine compound can be expressed as NH2-R-NH2, and the corresponding structure of the secondary amine chain extender can be expressed as:

[0018]

[0019] The aliphatic diol may include at least one of polytetramethylene ether glycol, polypropylene glycol, and polyneopentyl adipate glycol.

[0020] The hydroxyl value of the aliphatic diol may be 37.4 to 112 mgKOH / g, and further may be 56.1 to 62.3 mgKOH / g.

[0021] The aliphatic diisocyanate may include at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and 1,4-cyclohexyl diisocyanate.

[0022] The primary amine chain extender may include at least one of isophoronediamine, 1,2-propylenediamine, trimethylhexanediamine, 1,4-pentanediamine, 2-methyl-1,5-pentanediamine, 1,4-cyclohexanediamine, 1-methyl-2,4-cyclohexanediamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and diaminodicyclohexylmethane.

[0023] Furthermore, in the primary amine chain extender, the mass proportion of the isophorone diamine may be 50% to 100%.

[0024] The solvent may be N,N-dimethylformamide.

[0025] The terminator may be diethylamine.

[0026] The mass ratio of the primary diamine compound to the diethyl maleate may be 100:140-570.

[0027] The present invention prepares a secondary amine chain extender containing a large steric hindrance by an addition reaction between a primary diamine compound and diethyl maleate. In one embodiment, the preparation method of the secondary amine chain extender comprises: adding diethyl maleate dropwise to the primary diamine compound under inert gas protection and stirring at 40-70°C, and then heating the reaction temperature to 70-90°C to obtain the secondary amine chain extender. Furthermore, the diethyl maleate can be added at a rate of 2-6 g / min, and the reaction time at 70-90°C can be 24-48 hours.

[0028] The present invention also provides a method for preparing the aliphatic spandex elastic fiber, comprising the steps of:

[0029] S1, a prepolymer obtained by reacting an aliphatic diisocyanate with an aliphatic diol;

[0030] S2, dissolving the prepolymer obtained in step S1 in a solvent, adding a secondary amine chain extender under inert gas protection and stirring at 0-10° C. to react for 0.5-1 hour, then dropwise adding a primary amine chain extender and a terminator, mixing well, aging at 50-80° C., degassing to obtain a spandex spinning solution, and finally using a dry spandex spinning device for spinning and winding to obtain a finished aliphatic spandex elastic fiber.

[0031] The preparation method of the aliphatic spandex elastic fiber of the present invention can be summarized as follows:

[0032] 1) Aliphatic diisocyanate and aliphatic diol react to obtain a prepolymer;

[0033] 2) dissolving the prepolymer in a solvent, and adding a secondary amine chain extender, a primary amine chain extender and a terminator to react, and obtaining a spandex spinning solution after aging and degassing;

[0034] 3) The spandex spinning solution is used to prepare aliphatic spandex elastic fibers using a dry spinning device.

[0035] In one embodiment, step S1 may specifically include: under inert gas protection, stirring and reacting aliphatic diol and aliphatic diisocyanate at 50-60° C. for 0.5-1 hour, then heating to 80-90° C. and reacting for 4-6 hours to obtain a prepolymer.

[0036] In step S2, the primary amine chain extender and terminator may be diluted with a solvent in advance before being added dropwise.

[0037] Furthermore, the rate of adding the diluted primary amine chain extender and terminator dropwise may be 2 to 6 g / min.

[0038] The ratio of the solvent used to dilute the primary amine chain extender and the terminator to the solvent used to dissolve the prepolymer obtained in step S1 can be 1:1-2.

[0039] In step S2, the aging time may be 24 to 48 hours.

[0040] In step S2, the spinning and winding of the aliphatic spandex elastic fiber product using the dry-process spandex spinning equipment may specifically include: passing the spandex spinning solution through a spinneret and a hot air tunnel to evaporate the solvent, and then winding the solution to form the dry-process aliphatic spandex elastic fiber product.

[0041] The present invention uses a primary amine chain extender containing a sterically hindered group and simultaneously introduces a secondary amine chain extender containing a large steric hindrance, thereby increasing the steric hindrance of the spandex molecular chain and reducing the crystallization performance of the spandex, thereby solving the problem that the aliphatic isocyanate system spandex spinning solution is prone to gelling, and further effectively improving the yellowing resistance of the spandex.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The use of aliphatic diisocyanate avoids the yellowing of the benzene ring structure of diphenylmethane diisocyanate in conventional spandex formulas, greatly improving the yellowing resistance of spandex.

[0044] 2. By using a primary amine chain extender containing a steric hindrance group and introducing a secondary amine chain extender containing a large steric hindrance, the steric hindrance of the spandex molecular chain is increased, the crystallization performance of the spandex is reduced, thereby solving the problem of easy gelation of the aliphatic isocyanate system spandex spinning solution. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0046] The raw materials used in the following examples and comparative examples are all commercially available industrial products, wherein the hydroxyl values ​​of the relevant oligomeric aliphatic diols are: polyneopentyl adipate diol 56.1 mgKOH / g; polytetramethylene ether diol 62.3 mgKOH / g; and polypropylene glycol 56.1 mgKOH / g.

[0047] Example 1

[0048] 74.13 g of propylene diamine was added to the reactor, and under nitrogen protection, the temperature was maintained at 40 ° C. and stirred, and 344 g of diethyl maleate was added dropwise at a rate of 2 g / min. After the addition was completed, the temperature was raised to 80 ° C. and the reaction was carried out for 48 hours to obtain a secondary amine chain extender a for standby use; poly (neopentyl adipate glycol) diol and hexamethylene diisocyanate were added to the reactor in a mass ratio of 100:18.67, and under nitrogen protection, the stirring speed was 500 r / min, the temperature was controlled at 60 ° C., the reaction was carried out for 1 hour, and then the temperature was raised to 80 ° C. and the reaction was continued for 4 hours to obtain a prepolymer; 100 g of the prepolymer was dissolved in 140 g of N, N-dimethylformamide. After uniform dissolution, the temperature was lowered to about 7 ° C., 0.3 g of secondary amine chain extender a was added, and the reaction was carried out for 0.5 hours. Then, 100 g of the prepolymer was added dropwise at a rate of 2 g / min. A mixed solution consisting of N,N-dimethylformamide, 3.63g of isophorone diamine, 2.43g of 1,4-cyclohexane diamine, and 0.62g of diethylamine was mixed evenly and then aged at 50°C for 24h to obtain a spandex spinning solution; finally, a dry spandex spinning device was used for spinning and winding to obtain a spandex finished product.

[0049] Example 2

[0050] 116.21g of hexamethylenediamine was added to the reactor, and under nitrogen protection, the temperature was maintained at 50°C with stirring, and 344g of diethyl maleate was added dropwise at a rate of 2g / min. After the addition was completed, the temperature was raised to 80°C and the reaction was carried out for 48h to obtain the secondary amine chain extender b for standby use; polytetramethylene glycol and isophorone diisocyanate were added to the reactor in a mass ratio of 100:24.7, and under nitrogen protection, the stirring speed was 500r / min, the temperature was controlled at 60°C, the reaction was carried out for 1h, and then the temperature was raised to 80°C and the reaction was continued for 4h to obtain a prepolymer; 100g of the prepolymer was dissolved in 140g of N,N-dimethylformamide, and after uniform dissolution, the temperature was lowered to about 7°C, 0.3g of secondary amine chain extender b was added, and the reaction was carried out for 0.5h, and then 100g of N,N-dimethylformamide, 3.45g of isophorone diamine, 1.5g of A mixed solution consisting of 1,2-propylenediamine and 0.59g of diethylamine was mixed evenly and then aged at 50°C for 24h to obtain a spandex spinning solution; finally, a dry spandex spinning device was used for spinning and winding to obtain a spandex finished product.

[0051] Example 3

[0052] 102.18g of pentamethylenediamine was added to the reactor, and under nitrogen protection, the temperature was maintained at 40°C with stirring, and 344g of diethyl maleate was added dropwise at a rate of 2g / min. After the addition was completed, the temperature was raised to 80°C and the reaction was carried out for 48h to obtain the secondary amine chain extender C for standby use; polytetramethylene ether glycol, hexamethylene diisocyanate, and isophorone diisocyanate were added to the reactor in a mass ratio of 100:9.34:12.35, and under nitrogen protection, the stirring speed was 500r / min, the temperature was controlled at 60°C, the reaction was carried out for 1h, and then the temperature was raised to 80°C and the reaction was continued for 4h to obtain a prepolymer; 100g of the prepolymer was dissolved in 140g of N,N-dimethylformamide, and after uniform dissolution, the temperature was lowered to about 7°C, 0.5g of the secondary amine chain extender C was added, and the reaction was carried out for 0.5h, and then 100g of A mixed solution consisting of N,N-dimethylformamide, 3.55g isophorone diamine, 3.29g trimethylhexanediamine, and 0.61g diethylamine was mixed evenly and then aged at 60°C for 24h to obtain a spandex spinning solution; finally, a dry spandex spinning device was used for spinning and winding to obtain a spandex finished product.

[0053] Example 4

[0054] 114.19g of 1,4-cyclohexanediamine was added to the reactor, and under nitrogen protection, the temperature was maintained at 50°C with stirring, and 344g of diethyl maleate was added dropwise at a rate of 2g / min. After the addition was completed, the temperature was raised to 80°C and the reaction was continued for 48h to obtain the secondary amine chain extender d for standby use; polytetramethylene glycol, polypropylene glycol, and dicyclohexylmethane diisocyanate were added to the reactor in a mass ratio of 80:20:29.15, and under nitrogen protection, the stirring speed was 500r / min, the temperature was controlled at 60°C, the reaction was carried out for 1h, and then the temperature was raised to 80°C and the reaction was continued for 4h to obtain a prepolymer; 100g of the prepolymer was dissolved in 140g of After being uniformly dissolved in N,N-dimethylformamide, the temperature was lowered to about 7°C, 0.5g of secondary amine chain extender d was added and reacted for 0.5h, and then a mixed solution consisting of 100g of N,N-dimethylformamide, 6.66g of isophorone diamine, and 0.57g of diethylamine was added dropwise at a rate of 2g / min. After mixing evenly, the mixture was placed in an environment of 60°C and aged for 48h to obtain a spandex spinning solution; finally, a dry spandex spinning device was used for spinning and winding to obtain a spandex finished product.

[0055] Example 5

[0056] 210.36g of 4,4'-diaminodicyclohexylmethane was added to the reactor, and under nitrogen protection, the temperature was maintained at 50°C with stirring, and 344g of diethyl maleate was added dropwise at a rate of 2g / min. After the addition was completed, the temperature was raised to 85°C and the reaction was carried out for 48h to obtain the secondary amine chain extender e for standby use; polytetramethylene ether glycol, polypropylene glycol, and 1,4-cyclohexyl diisocyanate were added to the reactor in a mass ratio of 80:20:18.46, and under nitrogen protection, the stirring speed was 500r / min, the temperature was controlled at 60°C, the reaction was carried out for 1h, and then the temperature was raised to 80°C and the reaction was continued for 4h to obtain a prepolymer; 100g of the prepolymer was dissolved in 140g of N,N-dimethylformamide, and after uniform dissolution, the temperature was lowered to about 7°C, 0.5g of the secondary amine chain extender e was added, and the reaction was carried out for 1h, and then 100g of the prepolymer was added dropwise at a rate of 2g / min. A mixed solution consisting of N,N-dimethylformamide, 3.63g of isophorone diamine, 2.18g of 1,4-pentanediamine, and 0.62g of diethylamine was mixed evenly and then aged at 70°C for 24h to obtain a spandex spinning solution; finally, a dry spandex spinning device was used for spinning and winding to obtain a spandex finished product.

[0057] Example 6

[0058] 238.41g of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane was added to the reactor, and under nitrogen protection, the temperature was maintained at 50°C with stirring, and 344g of diethyl maleate was added dropwise at a rate of 2g / min. After the addition was completed, the temperature was raised to 85°C and the reaction was carried out for 48h to obtain the secondary amine chain extender f for standby use; polytetramethylene ether glycol, polypropylene glycol, and hexamethylene diisocyanate were added to the reactor in a mass ratio of 80:20:18.68, and under nitrogen protection, the stirring speed was 500r / min, the temperature was controlled at 60°C, the reaction was carried out for 1h, and then the temperature was raised to 80°C and the reaction was continued for 4h to obtain a prepolymer; 100g of the prepolymer was dissolved in 140g of N,N-dimethylformamide, and after uniform dissolution, the temperature was lowered to about 7°C, 1g of the secondary amine chain extender f was added, and the reaction was carried out for 1h, and then 100g of the prepolymer was added dropwise at a rate of 2g / min. A mixed solution consisting of N,N-dimethylformamide, 3.63g of isophorone diamine, 2.48g of 2-methyl-1,5-pentanediamine, and 0.62g of diethylamine was mixed evenly and then aged at 80°C for 24h to obtain a spandex spinning solution; finally, a dry spandex spinning device was used for spinning and winding to obtain a spandex finished product.

[0059] Comparative Example 1

[0060] The method of Comparative Example 1 is substantially the same as that of Example 1, except that no secondary amine chain extender a is added during the synthesis process. The spandex spinning solution prepared in this manner gelled after being placed in an environment of 25° C. for 3 days.

[0061] Comparative Example 2

[0062] The method of Comparative Example 2 is substantially the same as that of Example 1, except that 2.56 g of ethylenediamine is used in place of 3.63 g of isophoronediamine and 2.43 g of 1,4-cyclohexanediamine. The spandex spinning solution prepared in this manner immediately gelled.

[0063] Comparative Example 3

[0064] The method of Comparative Example 3 is basically the same as that of Example 1, except that the amount of secondary amine chain extender a added during the synthesis process is 2 g, and finally a dry-process spandex spinning equipment is used for spinning and winding to obtain a spandex finished product.

[0065] Comparative Example 4

[0066] Polytetramethylene glycol and diphenylmethane diisocyanate were added to a reactor in a mass ratio of 100:27.78. Under nitrogen protection, the stirring speed was 500 r / min, the temperature was controlled at 60°C, the reaction was carried out for 1 hour, and then the temperature was raised to 80°C and the reaction was continued for 2 hours to obtain a prepolymer. 100 g of the prepolymer was dissolved in 140 g of N,N-dimethylformamide. After uniform dissolution, the temperature was lowered to about 7°C, and a mixed solution consisting of 100 g of N,N-dimethylformamide, 1.17 g of ethylenediamine, 1.45 g of 1,2-propylenediamine, and 0.57 g of diethylamine was added dropwise at a rate of 2 g / min. After uniform mixing, the mixture was placed in an environment of 50°C and aged for 24 hours to obtain a spandex spinning solution. Finally, the prepolymer was spun and wound using a dry spandex spinning device to obtain a spandex finished product.

[0067] Comparative Example 5

[0068] The method of Comparative Example 5 is basically the same as that of Comparative Example 4, except that 1 g of spandex anti-yellowing agent HN-130 is additionally added to the mixed solution to obtain a spandex finished product.

[0069] Comparative Example 6

[0070] The method of Comparative Example 6 is basically the same as that of Comparative Example 4, except that 2 g of spandex anti-yellowing agent HN-130 is additionally added to the mixed solution to obtain a spandex finished product.

[0071] Comparative Example 7

[0072] The method of Comparative Example 7 is basically the same as that of Comparative Example 4, except that 1 g of spandex anti-yellowing agent HN-130 and 1 g of spandex anti-yellowing agent UDT are additionally added to the mixed solution to obtain a spandex finished product.

[0073] The spandex properties of each embodiment and comparative example were tested according to the test standard in FZ / T 54010-2014, and the properties are shown in Table 1 below.

[0074] Table 1

[0075]

[0076] As can be seen from the table above, the performance of aliphatic spandex is similar to that of conventional spandex (Comparative Examples 4-7), and can meet the requirements of conventional spandex applications. At the same time, as can be seen from Example 1 and Comparative Examples 1-3, when the formula contains no secondary amine chain extender or when a primary amine chain extender without steric hindrance, such as ethylenediamine, is used, the aliphatic spandex spinning solution is very prone to gel formation. When the secondary amine chain extender is used in the formula at a level of 2 g, which is 33% of the total mass of the primary amine chain extender, the prepared spandex yarn has a significant decrease in breaking strength, elongation at break, and 300% elastic recovery. Therefore, it is essential to use a primary amine chain extender with steric hindrance and to introduce a secondary amine chain extender with large steric hindrance in the present invention, while also stipulating that the secondary amine chain extender amount accounts for 1% to 30% of the total mass of the primary amine chain extender.

[0077] The spandex spinning solutions prepared in the examples and comparative examples were coated on flat glass to form films, and then placed in a 70°C UV aging test chamber and a 50°C sun lamp aging test chamber for 7 days to test the yellowing resistance of each sample. The specific indicators are shown in Table 2 below.

[0078] Table 2

[0079]

[0080] From the test data, the yellowing resistance of the spandex prepared in each embodiment is much higher than that of the spandex prepared with conventional spandex formulations in the comparative examples (Comparative Examples 4 to 7).

[0081] In summary, it can be seen that the basic properties of the aliphatic spandex of the present invention, such as breaking strength, elongation at break, and 300% elastic recovery rate, are similar to those of traditional spandex. At the same time, its yellowing resistance is very excellent, and it has great application prospects in the field of traditional spandex, especially light-colored spandex products.

[0082] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An aliphatic spandex elastic fiber, characterized in that: The raw materials include aliphatic diols, aliphatic diisocyanates, solvents, secondary amine chain extenders, primary amine chain extenders containing steric hindrance groups, and terminators; the primary amine chain extenders include at least one of isophorone diamine, 1,2-propylene diamine, trimethyl hexamethylene diamine, 1,4-pentamethylene diamine, 2-methyl-1,5-pentamethylene diamine, 1,4-cyclohexane diamine, 1-methyl-2,4-cyclohexane diamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and diaminodicyclohexylmethane; in the primary amine chain extenders, the mass proportion of isophorone diamine is 50% to 100%; The mass ratio of aliphatic diol to aliphatic diisocyanate is 100:18-30; The mass ratio of the prepolymer formed by the reaction of the aliphatic diol and the aliphatic diisocyanate to the solvent is 1:1 to 3; The mass ratio of the secondary amine chain extender to the primary amine chain extender is 1 to 30:100; The ratio of the total molar number of -NH- groups and -NH2 groups in the secondary amine chain extender and the primary amine chain extender to the molar number of isocyanate in the prepolymer formed by the reaction of the aliphatic diol and the aliphatic diisocyanate is 1:0.95-1.05; The mass ratio of the primary amine chain extender to the terminator is 5 to 15:1; The secondary amine chain extender is an addition reaction product of a primary diamine compound and diethyl maleate; The mass ratio of the primary diamine compound to the diethyl maleate is 100:140-570; The primary diamine compound includes at least one of propylene diamine, hexamethylene diamine, pentamethylene diamine, 1,4-cyclohexamethylene diamine, 4,4'-diaminodicyclohexylmethane, and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

2. The aliphatic spandex elastic fiber according to claim 1, characterized in that The aliphatic diol includes at least one of polytetramethylene ether glycol, polypropylene glycol, and polyneopentyl adipate glycol; The hydroxyl value of the aliphatic diol is 37.4 to 112 mgKOH / g.

3. The aliphatic spandex elastic fiber according to claim 1, characterized in that The hydroxyl value of the aliphatic diol is 56.1 to 62.3 mgKOH / g.

4. The aliphatic spandex elastic fiber according to claim 1, characterized in that The aliphatic diisocyanate includes at least one of isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and 1,4-cyclohexyl diisocyanate.

5. The aliphatic spandex elastic fiber according to claim 1, characterized in that The solvent is N,N-dimethylformamide; The terminator is diethylamine.

6. The aliphatic spandex elastic fiber according to claim 1, characterized in that The preparation method of the secondary amine chain extender comprises: adding diethyl maleate dropwise to a primary diamine compound under inert gas protection and stirring at 40-70° C., and heating the temperature to 70-90° C. after the addition is completed to react and obtain the secondary amine chain extender.

7. The aliphatic spandex elastic fiber according to claim 1, characterized in that The mass ratio of the secondary amine chain extender to the primary amine chain extender is 4 to 17:

100.

8. The aliphatic spandex elastic fiber according to claim 1, characterized in that The ratio of the total molar number of -NH- groups and -NH2 groups in the secondary amine chain extender and the primary amine chain extender to the molar number of isocyanate in the prepolymer generated by the reaction of the aliphatic diol and the aliphatic diisocyanate is 1:1.01-1.

03.

9. The method for preparing aliphatic spandex elastic fiber according to any one of claims 1 to 8, characterized in that: Including steps: S1, a prepolymer obtained by reacting an aliphatic diisocyanate with an aliphatic diol; S2, dissolving the prepolymer obtained in step S1 in a solvent, adding a secondary amine chain extender under inert gas protection and stirring at 0-10° C. to react for 0.5-1 hour, then dropwise adding a primary amine chain extender and a terminator, mixing well, aging at 50-80° C., degassing to obtain a spandex spinning solution, and finally using a dry spandex spinning device for spinning and winding to obtain a finished aliphatic spandex elastic fiber.

10. The preparation method according to claim 9, characterized in that Step S1 specifically comprises: under the protection of inert gas, stirring and reacting an aliphatic diol and an aliphatic diisocyanate at 50-60° C. for 0.5-1 hour, then heating to 80-90° C. for 4-6 hours to obtain a prepolymer; In step S2: The primary amine chain extender and terminator are diluted with solvent in advance and then added dropwise; The ratio of the solvent used to dilute the primary amine chain extender and the terminator to the solvent used to dissolve the prepolymer obtained in step S1 is 1:1-2; The diluted primary amine chain extender and terminator are added dropwise at a rate of 2 to 6 g / min; The aging time is 24 to 48 hours; The method of spinning and winding the finished aliphatic spandex elastic fiber using the dry-process spandex spinning equipment specifically includes: passing the spandex spinning solution through a spinneret and a hot air tunnel to evaporate the solvent, and then winding the solution to form the finished dry-process aliphatic spandex elastic fiber.

Images