Polyamide for industrial silk and preparation method and fiber thereof

Abstract

The present invention belongs to the technical field of polyamide fibers, and specifically relates to a polyamide for industrial silk and a preparation method and fiber thereof. The modified polyamide provided by the present invention has a structure shown in Formula I: wherein Q is a semi-aromatic amide structural unit, R is a phosphorus-containing semi-aromatic amide structural unit, S is an aliphatic amide structural unit, and P is a polyamide structural unit; a is 3 to 6, b is 4 to 8, c is 2 to 3, and d is 120 to 250. The present invention introduces an aromatic ring structure, a phosphorus-containing group and a long-chain polyamide segment into a polyamide molecular chain through an amide exchange reaction, utilizes the rigid benzene ring structure of the main chain and the side group to reduce the hydrogen bonding effect between the polyamide molecular chains, improves the proportion of amorphous regions of the modified polyamide and its drafting performance, utilizes the steric hindrance of the side group aromatic ring structure to improve its flowability and spinnability, utilizes the long-chain polyamide segment to improve the softness and mobility of the modified polyamide, and the modified polyamide has good spinning performance and drafting performance.

Description

Technical Field

[0001] The invention belongs to the technical field of polyamide fibers, and in particular relates to polyamide for industrial silk and a preparation method and fiber thereof. Background Art

[0002] Polyamide fiber is the earliest synthetic fiber to be industrially produced in the world. It has excellent mechanical properties, wear resistance and moisture absorption properties, and is widely used in various fields of people's lives. According to different application fields, polyamide fiber is divided into civil fiber and industrial fiber. In special application fields such as cord fabrics, parachutes, and climbing ropes, higher requirements are placed on the mechanical properties of polyamide fiber.

[0003] The existing method for preparing polyamide fibers with high mechanical properties mainly uses high-viscosity polyamide chips combined with subsequent spinning, drawing and shaping process adjustments to improve the mechanical properties of polyamide fibers. However, the mechanical strength of existing polyamide fibers with high mechanical properties is 7.0-9.0 cN / dtex, which cannot meet the requirements of special application fields for the mechanical strength of polyamide fibers, and its mechanical strength still needs to be improved. Summary of the invention

[0004] In view of this, the present invention provides a polyamide for industrial yarn and a preparation method and fiber thereof; the polyamide fiber prepared from the polyamide provided by the present invention has high breaking strength and breaking elongation, and can meet the requirements of special applications for the mechanical strength of the polyamide fiber.

[0005] In order to solve the above technical problems, the present invention provides a modified polyamide having a structure shown in Formula I:

[0006]

[0007] Wherein, Q is a semi-aromatic amide structural unit, R is a phosphorus-containing semi-aromatic amide structural unit, S is an aliphatic amide structural unit, and P is a polyamide structural unit;

[0008] a is 3 to 6, b is 4 to 8, c is 2 to 3, and d is 120 to 250.

[0009] Preferably, Q has a structure shown in any one of Formulas 1 to 5:

[0010]

[0011]

[0012] Wherein, x is any integer from 4 to 14.

[0013] Preferably, the R has a structure shown in any one of Formulas 6 to 8:

[0014]

[0015] Wherein, y is any integer from 4 to 14.

[0016] Preferably, the S has a structure shown in Formula 9:

[0017]

[0018] Here, m is an arbitrary integer from 8 to 12, and n is an arbitrary integer from 10 to 14.

[0019] Preferably, the P has a structure shown in any one of Formulas 10 to 12:

[0020]

[0021] The polyamide structural unit includes a polyamide 66 structural unit, a polyamide 6 structural unit or a polyamide 56 structural unit.

[0022] The present invention also provides a method for preparing the modified polyamide described in the above technical solution, comprising the following steps:

[0023] Dissolving an aromatic dibasic acid and a first aliphatic diamine in a first solvent, and performing a first salt-forming reaction to obtain a semi-aromatic amide salt;

[0024] dissolving the phosphorus-containing aromatic dibasic acid and the second aliphatic diamine in a second solvent, and performing a second salt-forming reaction to obtain a phosphorus-containing semi-aromatic amide salt;

[0025] dissolving the aliphatic dibasic acid and the third aliphatic diamine in a third solvent, and performing a third salt-forming reaction to obtain an aliphatic amide salt;

[0026] The semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt, molecular weight regulator and water are mixed to carry out melt polycondensation reaction to obtain a functional polymer;

[0027] The functional polymer and polyamide are mixed and subjected to amide exchange reaction to obtain the modified polyamide.

[0028] Preferably, the molar ratio of the aromatic dibasic acid to the first aliphatic diamine is 1:0.98-1.05;

[0029] The molar ratio of the phosphorus-containing aromatic dibasic acid to the second aliphatic diamine is 1:0.98-1.05;

[0030] The molar ratio of the aliphatic dibasic acid to the third aliphatic diamine is 1:0.98-1.05;

[0031] The temperatures of the first salt-forming reaction, the second salt-forming reaction and the third salt-forming reaction are independently 60 to 90° C., and the times of the first salt-forming reaction, the second salt-forming reaction and the third salt-forming reaction are independently 0.5 to 5 hours.

[0032] Preferably, before the melt polycondensation reaction, the process further comprises: mixing the semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt, molecular weight regulator and water to perform a prepolymerization reaction;

[0033] The molar ratio of the aromatic amide salt to the phosphorus-containing semi-aromatic amide salt is 3-6:4-8;

[0034] The molar ratio of the aromatic amide salt to the aliphatic amide salt is 3-6:2-3;

[0035] The pressure of the prepolymerization reaction is 0.5-2.5 MPa; the temperature of the prepolymerization reaction is 200-250° C.; and the time of the prepolymerization reaction is 1-3 hours.

[0036] Preferably, the vacuum degree of the melt polycondensation reaction is 10 to 200 Pa; the temperature of the melt polycondensation reaction is 220 to 280° C.; the time of the melt polycondensation reaction is 1 to 3 hours;

[0037] The mass ratio of the functional polymer to the polyamide is 10-20:100; the temperature of the amide exchange reaction is 260-280° C.; and the time of the amide exchange reaction is 0.5-3 hours.

[0038] The present invention also provides a modified polyamide fiber, which is prepared from the modified polyamide described in the above technical solution or the modified polyamide prepared by the preparation method described in the above technical solution.

[0039] The present invention provides a modified polyamide having a structure shown in Formula I: Among them, Q is a semi-aromatic amide structural unit, R is a phosphorus-containing semi-aromatic amide structural unit, S is an aliphatic amide structural unit, and P is a polyamide structural unit; a is 3 to 6, b is 4 to 8, c is 2 to 3, and d is 120 to 250. The present invention introduces aromatic ring structures and phosphorus-containing aromatic ring groups into polyamide molecular chains to provide a modified polyamide having an aromatic ring structure and a phosphorus-containing aromatic ring structure; the rigid benzene ring structure and the phosphorus-containing flame retardant structure are used to reduce the hydrogen bonding between polyamide molecular chains, thereby reducing the generation of hydrogen bonds in polyamide molecules, increasing the proportion of amorphous regions of the modified polyamide, and improving the drafting properties of the modified polyamide fiber prepared from the modified polyamide; the steric hindrance of the side aromatic ring structure is used to increase the distance between polyamide molecular chains, thereby reducing the molecular chain entanglement of high-viscosity polyamide, reducing its structural viscosity index, and improving its flowability and spinnability. The aromatic ring structure improves the drawing performance and mechanical strength of the polyamide fiber, but its elongation at break is reduced due to the rigidity of the molecular chain. The present invention simultaneously introduces a long-chain aliphatic amide structural unit into the modified polyamide to improve the elongation at break of its fiber. The long-chain polyamide structural unit is beneficial to improving the softness and mobility of the modified polyamide, thereby improving the elongation at break of the modified polyamide fiber and achieving moderate rigidity and flexibility of the modified polyamide fiber.

[0040] The present invention also provides a method for preparing the modified polyamide described in the above technical solution, comprising the following steps: dissolving an aromatic dibasic acid and a first aliphatic diamine in a first solvent, performing a first salt-forming reaction, and obtaining a semi-aromatic amide salt; dissolving a phosphorus-containing aromatic dibasic acid and a second aliphatic diamine in a second solvent, performing a second salt-forming reaction, and obtaining a phosphorus-containing semi-aromatic amide salt; dissolving an aliphatic dibasic acid and a third aliphatic diamine in a third solvent, performing a third salt-forming reaction, and obtaining an aliphatic amide salt; mixing the semi-aromatic amide salt, the phosphorus-containing semi-aromatic amide salt, the aliphatic amide salt, a molecular weight regulator and water, performing a melt polycondensation reaction, and obtaining a functional polymer; mixing the functional polymer and polyamide, performing an amide exchange reaction, and obtaining the modified polyamide. The present invention first prepares a functional polymer through a melt polycondensation reaction of an aromatic dibasic acid, a phosphorus-containing dibasic acid and an aliphatic amide salt, and then introduces a rigid benzene ring structure, an aliphatic amide structure and a phosphorus-containing flame retardant structure into a polyamide molecular chain through an amide exchange reaction; the rigid benzene ring structure and the phosphorus-containing flame retardant structure of the functional polymer are combined with the polyamide molecular chain through the amide exchange reaction, which will not reduce the polymerization degree and molecular weight of the polyamide molecular chain, and the addition ratio of the functional components can be flexibly designed to obtain a modified polyamide fiber with high mechanical properties, and the aliphatic amide structure can significantly improve the elongation at break of the modified polyamide. DETAILED DESCRIPTION

[0041] The present invention provides a modified polyamide having a structure shown in Formula I:

[0042]

[0043] Wherein, Q is a semi-aromatic amide structural unit. In the present invention, Q preferably has a structure shown in any one of Formulas 1 to 5:

[0044] More preferably Here, x is preferably an integer of 4-14, and more preferably an integer of 6-12.

[0045] In the present invention, R is a phosphorus-containing semi-aromatic amide structural unit; the R preferably has a structure shown in any one of Formulas 6 to 8:

[0046] Formula 8, more preferably Here, y is preferably an integer of 4 to 14, and more preferably an integer of 6 to 12.

[0047] In the present invention, the R and Q structural units jointly improve the mechanical properties of the modified polyamide, while the R structural unit as a flame retardant also improves the flame retardant properties of the modified polyamide.

[0048] In the present invention, S is an aliphatic amide structural unit, and the S preferably has a structure shown in Formula 9:

[0049]

[0050] Among them, m is preferably any integer from 8 to 12, and more preferably any integer from 10 to 12; n is preferably any integer from 10 to 14, and more preferably any integer from 12 to 14.

[0051] In the present invention, P is a polyamide structural unit, and the polyamide structural unit preferably includes a polyamide 66 structural unit, a polyamide 6 structural unit or a polyamide 56 structural unit, and more preferably a polyamide 66 structural unit or a polyamide 6 structural unit. In the present invention, the P preferably has a structure shown in any one of formulas 10 to 12:

[0052] More preferably

[0053] In the present invention, a is 3 to 6, preferably 4 to 5; b is 4 to 8, preferably 5 to 7; c is 2 to 3, and d is 120 to 250. When P is a polyamide 6 structural unit, d is preferably 230 to 250, and more preferably 240 to 250; when P is a polyamide 66 structural unit, d is preferably 120 to 140, and more preferably 130 to 140; when P is a polyamide 56 structural unit, d is preferably 120 to 140, and more preferably 130 to 140.

[0054] The present invention also provides a method for preparing the modified polyamide described in the above technical solution, comprising the following steps:

[0055] Dissolving an aromatic dibasic acid and a first aliphatic diamine in a first solvent, and performing a first salt-forming reaction to obtain a semi-aromatic amide salt;

[0056] dissolving the phosphorus-containing aromatic dibasic acid and the second aliphatic diamine in a second solvent, and performing a second salt-forming reaction to obtain a phosphorus-containing semi-aromatic amide salt;

[0057] dissolving the aliphatic dibasic acid and the third aliphatic diamine in a third solvent, and performing a third salt-forming reaction to obtain an aliphatic amide salt;

[0058] The semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt, molecular weight regulator and water are mixed to carry out melt polycondensation reaction to obtain a functional polymer;

[0059] The functional polymer and polyamide are mixed and subjected to amide exchange reaction to obtain the modified polyamide.

[0060] In the present invention, an aromatic dibasic acid and a first aliphatic diamine are dissolved in a first solvent, and a first salt-forming reaction is performed to obtain a semi-aromatic amide salt. In the present invention, the aromatic dibasic acid preferably includes More preferably In the present invention, the first aliphatic diamine preferably has a structure shown in formula a:

[0061]

[0062] Among them, f is preferably any integer from 4 to 14, and more preferably any integer from 6 to 12.

[0063] In the present invention, the first solvent preferably includes water or ethanol, more preferably ethanol.

[0064] In the present invention, the molar ratio of the aromatic dibasic acid to the first aliphatic diamine is preferably 1:0.98-1.05, more preferably 1:1. In the present invention, the mass ratio of the total mass of the aromatic dibasic acid and the first aliphatic diamine to the first solvent is preferably 1:3-6, more preferably 1:3-4.

[0065] The present invention has no special requirements for the dissolution, as long as it can be completely dissolved. In the present invention, the temperature of the first salt-forming reaction is preferably 60 to 90°C, more preferably 70 to 80°C; the time of the first salt-forming reaction is preferably 0.5 to 5h, more preferably 1 to 4h. In the present invention, the first salt-forming reaction is preferably accompanied by stirring. In the present invention, the stirring speed is preferably 20 to 100r / min, more preferably 40 to 80r / min.

[0066] In the present invention, a phosphorus-containing aromatic dibasic acid and a second aliphatic diamine are dissolved in a second solvent, and a second salt-forming reaction is performed to obtain a phosphorus-containing semi-aromatic amide salt. In the present invention, the phosphorus-containing aromatic dibasic acid preferably includes More preferably In the present invention, the second aliphatic diamine is preferably the same as the first aliphatic diamine, and will not be repeated here. In the present invention, the second solvent preferably includes water or ethanol, and more preferably ethanol.

[0067] In the present invention, the molar ratio of the phosphorus-containing aromatic dibasic acid to the second aliphatic diamine is 1:0.98-1.05, more preferably 1:1. In the present invention, the mass ratio of the total mass of the phosphorus-containing aromatic dibasic acid to the second aliphatic diamine to the second solvent is preferably 1:3-6, more preferably 1:3-4.

[0068] The present invention has no special requirements for the dissolution, as long as it can be completely dissolved. In the present invention, the temperature of the second salt-forming reaction is preferably 60 to 90°C, more preferably 70 to 80°C; the time of the second salt-forming reaction is preferably 0.5 to 5h, more preferably 1 to 4h. In the present invention, the second salt-forming reaction is preferably accompanied by stirring. In the present invention, the stirring speed is preferably 20 to 100r / min, more preferably 40 to 80r / min.

[0069] In the present invention, the aliphatic dibasic acid and the third aliphatic diamine are dissolved in a third solvent, and a third salt-forming reaction is performed to obtain an aliphatic amide salt. In the present invention, the aliphatic dibasic acid preferably has a structure shown in formula b:

[0070]

[0071] Wherein, e is preferably any integer from 8 to 12, and more preferably any integer from 10 to 12. In the present invention, the third aliphatic diamine is a linear diamine having 10 to 14 carbon atoms, and more preferably a linear diamine having 12 to 14 carbon atoms. In the present invention, the third solvent preferably includes water or ethanol, and more preferably ethanol.

[0072] In the present invention, the molar ratio of the aliphatic dibasic acid to the first aliphatic diamine is preferably 1:0.98-1.05, more preferably 1:1. In the present invention, the mass ratio of the total mass of the aliphatic dibasic acid and the third aliphatic diamine to the third solvent is preferably 1:3-6, more preferably 1:3-4.

[0073] The present invention has no special requirements for the dissolution, as long as it can be completely dissolved. In the present invention, the temperature of the third salt-forming reaction is preferably 60 to 90°C, more preferably 70 to 80°C; the time of the third salt-forming reaction is preferably 0.5 to 5h, more preferably 1 to 4h. In the present invention, the third salt-forming reaction is preferably accompanied by stirring. In the present invention, the stirring speed is preferably 20 to 100r / min, more preferably 40 to 80r / min.

[0074] After obtaining the semi-aromatic amide salt, the phosphorus-containing semi-aromatic amide salt and the aliphatic amide salt, the present invention mixes the semi-aromatic amide salt, the phosphorus-containing semi-aromatic amide salt, the aliphatic amide salt, the molecular weight regulator and water to carry out a melt polycondensation reaction to obtain a functional polymer. In the present invention, before the melt polycondensation reaction, it is preferred that the semi-aromatic amide salt, the phosphorus-containing semi-aromatic amide salt, the aliphatic amide salt, the molecular weight regulator and water are mixed to carry out a prepolymerization reaction.

[0075] In the present invention, the molecular weight regulator preferably includes one or more of terephthalic acid, adipic acid and acetic acid, more preferably adipic acid. In the present invention, the water is preferably deionized water.

[0076] In the present invention, the molar ratio of the semi-aromatic amide salt and the phosphorus-containing semi-aromatic amide salt is preferably 3-6:4-8, more preferably 3-4:4-6, and most preferably 3:4. In the present invention, the molar ratio of the semi-aromatic amide salt and the aliphatic amide salt is preferably 3-6:2-3, more preferably 3-4:2-3. In the present invention, the mass ratio of the total mass of the semi-aromatic amide salt, the phosphorus-containing semi-aromatic amide salt and the aliphatic amide salt to the molecular weight regulator is preferably 100:0.05-0.2, more preferably 100:0.1-0.15. In the present invention, the mass ratio of the total mass of the aromatic amide salt, the phosphorus-containing semi-aromatic amide salt and the aliphatic amide salt to water is preferably 100:80-120, more preferably 100:90-110.

[0077] In the present invention, the pressure of the prepolymerization reaction is preferably 0.5-2.5 MPa, more preferably 1-2 MPa; the temperature of the prepolymerization reaction is preferably 200-250°C, more preferably 220-250°C; the time of the prepolymerization reaction is preferably 1-3 h, more preferably 1-2 h.

[0078] In the present invention, the prepolymerization reaction is preferably carried out in a protective atmosphere, and the protective atmosphere preferably includes nitrogen or argon, more preferably nitrogen. In the present invention, the prepolymerization reaction is preferably carried out in a polymerization kettle.

[0079] The present invention can avoid the decomposition reaction of the amide salt or the degradation side reaction of the polyamide when the aromatic amide salt, the phosphorus-containing semi-aromatic amide salt and the aliphatic amide salt are directly polymerized at a high temperature through the prepolymerization reaction, and the present invention is conducive to the preparation of high molecular weight functional polymers through prepolymerization. In the present invention, the product of the prepolymerization reaction is a primary functional polymer with a certain degree of polymerization and a relatively small molecular weight.

[0080] In the present invention, the vacuum degree of the melt polycondensation reaction is preferably 10-200 Pa, more preferably 10-100 Pa; the temperature of the melt polycondensation reaction is preferably 220-280°C, more preferably 240-260°C; the time of the melt polycondensation reaction is preferably 1-3 hours, more preferably 2-3 hours. In the present invention, the melt polycondensation reaction is preferably carried out under a protective atmosphere, and the protective atmosphere is preferably consistent with the protective atmosphere of the prepolymerization. In the present invention, it is preferred to reduce the pressure to normal pressure under the pressure conditions of the prepolymerization reaction, and then evacuate to the vacuum degree required for the melt polycondensation reaction. In the present invention, the normal pressure is the standard atmospheric pressure, and the standard atmospheric pressure is 1.0×10 5 Pa. The present invention has no special requirements for the pressure reduction method, and the conventional method in the art can be used. In the present invention, the time for reducing the pressure from the prepolymerization reaction pressure to normal pressure is preferably 30 min to 120 min, more preferably 60 to 90 min.

[0081] In the present invention, the melt polycondensation reaction is preferably accompanied by stirring, and the stirring speed is preferably 20 to 100 r / min, more preferably 40 to 80 r / min.

[0082] In the present invention, the functional polymer preferably has a structure shown in formula c:

[0083]

[0084] Among them, j is preferably 30-60, more preferably 40-50; k is preferably 40-80, more preferably 50-70; l is preferably 20-30, more preferably 25-30.

[0085] After obtaining the functional polymer, the present invention mixes the functional polymer with polyamide and performs an amide exchange reaction to obtain the modified polyamide. In the present invention, the polyamide preferably includes polyamide 6, polyamide 66 or polyamide 56, more preferably polyamide 6 or polyamide 66. In the present invention, the mass ratio of the functional polymer to the polyamide is preferably 10 to 20:100, more preferably 10 to 15:100.

[0086] In the present invention, the temperature of the amide exchange reaction is preferably 260-280° C., more preferably 265-275° C.; the time of the amide exchange reaction is preferably 0.5-3 h, more preferably 0.5-1.5 h.

[0087] In the present invention, the functional polymer and the polyamide undergo an amide exchange reaction in a molten state.

[0088] In the present invention, the functional polymer prepared is preferably in a molten state. In the present invention, when the polyamide is a molten polyamide, the device for the transamide reaction preferably includes a polymerization kettle and a polymerization pipeline, more preferably a polymerization kettle. When the polyamide is a polyamide slice, the functional polymer and the polyamide slice are preferably melt-blended in a twin-screw extruder to perform the transamide reaction.

[0089] The invention can introduce more R structural units through amide exchange reaction, thereby improving the flame retardancy of the modified polyamide.

[0090] The present invention synthesizes an aromatic ring structure, a flame retardant structure and an aliphatic amide structure into a functional polymer through a melt polycondensation reaction, and the functional polymer improves the flame retardancy of the modified polyamide while improving the mechanical properties of the modified polyamide. In the process of preparing the functional polymer, only small molecular water is removed, and no harmful chemical substances are discharged, so the present invention has the characteristics of being green and environmentally friendly.

[0091] The functional polymer prepared by the present invention is combined with the polyamide molecular chain through an amide exchange reaction, and a high-performance polyamide fiber with high mechanical properties and flame retardant properties is obtained through melt spinning. The proportion and addition path of the functional polymer can be flexibly adjusted according to demand. The preparation method of the high-performance polyamide fiber has the characteristics of small addition amount, flexible and efficient, and long-lasting performance.

[0092] The present invention also provides a modified polyamide fiber, which is prepared from the modified polyamide described in the above technical solution or the modified polyamide prepared by the preparation method described in the above technical solution. In the present invention, the method for preparing the polyamide fiber is preferably to use the modified polyamide for melt spinning. In the present invention, the temperature of the melt spinning is preferably 270 to 310°C, more preferably 280 to 300°C; the winding speed in the melt spinning is preferably 2500 to 4000 m / min, more preferably 3000 to 4000 m / min; the draft ratio in the melt spinning is preferably 5 to 6, more preferably 5.0 to 5.5.

[0093] In the present invention, the breaking strength of the modified polyamide fiber is preferably 9.2 to 10.9 cN / dtex, the breaking elongation is preferably 15.2 to 28.7%, and the limiting oxygen index is preferably 30.3 to 35.7%.

[0094] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0095] Preparation of modified polyamide

[0096] Example 1

[0097] 5 mol (830.65 g) of terephthalic acid and 5 mol (581 g) of hexamethylenediamine were dissolved in 4235 g of ethanol, and a first salt-forming reaction was carried out at 70° C. (accompanied by stirring at a speed of 60 r / min) for 1 h to obtain hexamethylenediamine terephthalate;

[0098] 5 mol (1731 g) of 9,10-dihydro-9-oxa-10-phosphorylphenanthrene-succinic acid (DDP) and 5 mol (581 g) of hexamethylenediamine were dissolved in 6936 g of ethanol, and a second salt-forming reaction was carried out at 60° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain hexamethylenediamine DDP salt;

[0099] 5 mol of sebacic acid (1013.75 g) and 5 mol (861.5 g) of decanediamine were dissolved in 5625.8 g of ethanol, and a third salt-forming reaction was carried out at 60° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine sebacate;

[0100] 3 mol (847 g) of hexamethylenediamine terephthalate, 4 mol (1850 g) of hexamethylenediamine DDP salt, 2 mol (750 g) of decanediamine sebacate, 3447 g of deionized water and 3.5 g of adipic acid were added into a polymerization kettle, nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 2.0 MPa, and after a prepolymerization reaction at 230° C. for 2 h, the pressure was released to normal pressure in 30 min, and then evacuated to a vacuum degree of 200 Pa, and melt polycondensation reaction was carried out at 260° C. (accompanied by stirring at a speed of 50 r / min) for 2 h to obtain a functional polymer in a molten state;

[0101] The functional polymer in a molten state is mixed with the polyamide 6 in a molten state at a mass ratio of 10:100, and an amide exchange reaction is carried out at 270° C. for 1 hour to obtain a modified polyamide 6; the structural formula of the modified polyamide 6 is:

[0102]

[0103] Example 2

[0104] 5 mol (830.65 g) of isophthalic acid and 5 mol (861.55 g) of decanediamine were dissolved in 5077 g of ethanol, and a first salt-forming reaction was carried out at 80° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine isophthalate;

[0105] Dissolve 5 mol (1781.55 g) of 2,3-dicarboxypropyl diphenylphosphine oxide (DPOIA) and 5 mol (861.55 g) of decanediamine in 7930 g of ethanol, and perform a second salt-forming reaction at 80° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine DPOIA salt;

[0106] Dissolve 5 mol of dodecanedioic acid (1081.35 g) and 5 mol (861.5 g) of decanediamine in 5826.55 g of ethanol, and perform a third salt-forming reaction at 60° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine dodecanedioate;

[0107] 3 mol (1015.32 g) of decanediamine isophthalate, 4 mol (2114.48 g) of decanediamine DPOIA salt, 2 mol (777.14 g) of decanediamine dodecanedioate, 3906.94 g of deionized water and 3.9 g of terephthalic acid were added into a polymerization kettle, nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 1.8 MPa, and after a prepolymerization reaction at 260° C. for 1 hour, the pressure was released to normal pressure at 90 minutes, and then evacuated to a vacuum degree of 100 Pa, and melt polycondensation reaction was carried out at 260° C. (accompanied by stirring at a speed of 50 r / min) for 3 hours to obtain a functional polymer in a molten state;

[0108] The functional polymer in a molten state is mixed with the polyamide 66 in a molten state at a mass ratio of 15:100, and an amide exchange reaction is carried out at 275° C. for 1.5 hours to obtain a modified polyamide 66; the structural formula of the modified polyamide 66 is:

[0109]

[0110] Example 3

[0111] 5 mol (1080.95 g) of 1,4-naphthalenedicarboxylic acid and 5 mol (581 g) of hexamethylenediamine were dissolved in 6648 g of ethanol, and a first salt-forming reaction was carried out at 80° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain hexamethylenediamine naphthalenedicarboxylate;

[0112] 5 mol (1070.75 g) of 2-carboxyethylphenylphosphinic acid (CEPPA) and 5 mol (861.55 g) of decanediamine were dissolved in 7730 g of ethanol, and a second salt-forming reaction was carried out at 80° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine CEPPA salt;

[0113] 5 mol of dodecanedioic acid (1141.43 g) and 5 mol (861.5 g) of decanediamine were dissolved in 6008.8 g of ethanol, and a third salt-forming reaction was carried out at 70° C. (accompanied by stirring at a speed of 50 r / min) for 2 h to obtain decanediamine dodecanedioate;

[0114] 3 mol (1015.32 g) of hexamethylenediamine naphthalate, 4 mol (1545.84 g) of decanediamine CEPPA salt, 2 mol (801.2 g) of decanediamine dodecanedioate, 3362.4 g of deionized water and 3.4 g of adipic acid were added into a polymerization kettle, nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 2.0 MPa, and after a prepolymerization reaction at 260° C. for 1 hour, the pressure was released to normal pressure in 60 minutes, and then evacuated to a vacuum degree of 100 Pa, and melt polycondensation reaction was carried out at 270° C. (accompanied by stirring at a speed of 50 r / min) for 2 hours to obtain a functional polymer in a molten state;

[0115] The functional polymer in a molten state is mixed with the polyamide 56 in a molten state at a mass ratio of 15:100, and an amide exchange reaction is carried out at 275° C. for 1 hour to obtain a modified polyamide 56; the structural formula of the modified polyamide 56 is:

[0116]

[0117] Preparation of modified polyamide fibers

[0118] Example 4

[0119] The modified polyamide 6 prepared in Example 1 is melt-spinned to obtain modified polyamide 6 fibers;

[0120] The melt spinning temperature was 280° C., the take-up speed was 4000 m / min, and the draft ratio was 5.0.

[0121] Example 5

[0122] The modified polyamide 66 prepared in Example 2 is melt-spun to obtain modified polyamide 66 fibers;

[0123] The melt spinning temperature was 275° C., the take-up speed was 3500 m / min, and the draft ratio was 5.2.

[0124] Example 6

[0125] The modified polyamide 56 prepared in Example 3 is melt-spinned to obtain modified polyamide 56 fibers;

[0126] The melt spinning temperature was 270° C., the take-up speed was 3000 m / min, and the draft ratio was 5.5.

[0127] The mechanical properties of the modified polyamide fibers prepared in Examples 4 to 6 were tested according to GB / T 14344-2008 "Test Method for Tensile Properties of Chemical Fiber Filaments", wherein the clamping distance was 250 mm and the tensile speed was 500 mm / min; the flame retardant properties of the fabrics woven from the modified polyamide fibers in Examples 4 to 6 were tested according to GB / T 5454-1997 "Textile Combustion Performance Test Oxygen Index Method", and the results are shown in Table 1. The present invention has no special requirements for the method of weaving fabrics using modified polyamide fibers, and the conventional method in the art can be used.

[0128] Table 1 Mechanical properties and flame retardant properties of modified polyamide fibers prepared in Examples 4 to 6

[0129] Example Breaking strength (cN / dtex) Elongation at break (%) Limiting oxygen index (%) Example 4 10.9 15.2 30.3 Example 5 10.1 24.5 34.2 Example 6 9.2 28.7 35.7

[0130] It can be seen from Table 1 that the modified polyamide fiber prepared using the modified polyamide provided by the present invention as a raw material has high mechanical strength and flame retardant properties, and can be applied to special application fields such as cord fabrics, parachutes, and climbing ropes.

[0131] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A modified polyamide for industrial yarn, having any of the following structures: Modified polyamide 66 for industrial yarn, Modified polyamide 56 for industrial yarn.

2. The method for preparing the modified polyamide according to claim 1, comprising the following steps: Dissolve 5 mol of isophthalic acid and 5 mol of decanediamine in 5077 g of ethanol, and perform a first salt-forming reaction at 80° C. for 1 h to obtain decanediamine isophthalate; Dissolve 5 mol of 2,3-dicarboxypropyl diphenylphosphine oxide and 5 mol of decanediamine in 7930 g of ethanol, and perform a second salt-forming reaction at 80° C. for 1 h to obtain decanediamine DPOIA salt; Dissolve 5 mol of dodecanedioic acid and 5 mol of decanediamine in 5826.55 g of ethanol, and perform a third salt-forming reaction at 60° C. for 1 h to obtain decanediamine dodecanedioate; 3 mol of decanediamine isophthalate, 4 mol of decanediamine DPOIA salt, 2 mol of decanediamine dodecanedioate, 3906.94 g of deionized water and 3.9 g of terephthalic acid were added into a polymerization kettle, nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 1.8 MPa, and after a prepolymerization reaction at 260° C. for 1 hour, the pressure was released to normal pressure after 90 minutes, and then evacuated to a vacuum degree of 100 Pa, and melt polycondensed at 260° C. for 3 hours to obtain a functional polymer in a molten state; The functional polymer in a molten state is mixed with the polyamide 66 in a molten state at a mass ratio of 15:100, and an amide exchange reaction is carried out at 275° C. for 1.5 hours to obtain a modified polyamide 66 for industrial yarn; Alternatively, include the following steps: Dissolve 5 mol of 1,4-naphthalene dicarboxylic acid and 5 mol of hexamethylenediamine in 6648 g of ethanol, and perform a first salt-forming reaction at 80° C. for 1 h to obtain hexamethylenediamine naphthalene dicarboxylate; Dissolve 5 mol of 2-carboxyethylphenylphosphinic acid and 5 mol of decanediamine in 7730 g of ethanol, and perform a second salt-forming reaction at 80° C. for 1 h to obtain decanediamine CEPPA salt; Dissolve 5 mol of dodecanedioic acid and 5 mol of decanediamine in 6008.8 g of ethanol, and perform a third salt-forming reaction at 70° C. for 2 h to obtain decanediamine dodecanedioate; 3 mol of hexamethylenediamine naphthalate, 4 mol of decanediamine CEPPA salt, 2 mol of decanediamine dodecanedioate, 3362.4 g of deionized water and 3.4 g of adipic acid were added into a polymerization kettle, nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 2.0 MPa, and after a prepolymerization reaction at 260° C. for 1 hour, the pressure was released to normal pressure after 60 minutes, and then evacuated to a vacuum degree of 100 Pa, and melt polycondensed at 270° C. for 2 hours to obtain a functional polymer in a molten state; The functional polymer in a molten state was mixed with the polyamide 56 in a molten state at a mass ratio of 15:100, and an amide exchange reaction was carried out at 275° C. for 1 hour to obtain modified polyamide 56 for industrial yarn.

3. A modified polyamide fiber, prepared from the modified polyamide according to claim 1 or the modified polyamide prepared by the preparation method according to claim 2.

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