Polyamide material for industrial yarn and preparation method thereof, fiber

Abstract

The present invention belongs to the technical field of polyamide fibers, and specifically relates to a polyamide material for industrial silk, a preparation method thereof, and fibers. 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 1 to 3, c is 2 to 5, and d is 110 to 240. The present invention introduces aromatic ring structure, phosphorus-containing group and flexible chain segment into polyamide molecular chain through copolymerization, utilizes rigid benzene ring structure and phosphorus-containing flame retardant structure to reduce hydrogen bonding between polyamide molecular chains, increases the proportion of amorphous region of modified polyamide, utilizes long-chain polyamide flexible chain segment to improve the softness and activity of modified polyamide, and at the same time, the side group phosphorus-containing aromatic ring structure also improves the flame retardant performance of modified polyamide.

Description

Technical Field

[0001] The invention belongs to the technical field of polyamide fibers, and in particular relates to a polyamide material for industrial yarn 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 material for industrial yarn and a preparation method and fiber; 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 polyamide fibers.

[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 1 to 3, c is 2 to 5, and d is 110 to 240.

[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 6 structural unit, a polyamide 66 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, polyamide monomer, molecular weight regulator and water are mixed to perform a prepolymerization reaction to obtain a prepolymer;

[0027] The prepolymer is subjected to polymerization 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, the molar ratio of the semi-aromatic amide salt to the phosphorus-containing semi-aromatic amide salt is 3-6:1-3;

[0033] The molar ratio of the semi-aromatic amide salt to the aliphatic amide salt is 3-6:2-5

[0034] The molar ratio of the semi-aromatic amide salt to the polyamide monomer is 3-6:110-240;

[0035] The pressure of the prepolymerization reaction is 1.7-2.5 MPa; the temperature of the prepolymerization reaction is 220-250° C.; and the time of the prepolymerization reaction is 1-3 hours.

[0036] Preferably, the vacuum degree of the polymerization reaction is 10-800 Pa, the temperature of the polymerization reaction is 260-280° C., and the time of the polymerization reaction is 1-3 h.

[0037] 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.

[0038] 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 1 to 3, c is 2 to 5, and d is 110 to 240. The present invention simultaneously introduces a rigid benzene ring structure into the modified polyamide main chain and the side group, destroying the regularity within and between the molecular chains of the modified polyamide, thereby reducing the formation of hydrogen bonds in the polyamide molecules, increasing the proportion of the amorphous region 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 the polyamide molecular chains, thereby reducing the molecular chain entanglement of the high-viscosity polyamide, reducing its structural viscosity index, and improving its flowability and spinnability. In the present invention, the phosphorus-containing semi-aromatic amide reduces the crystallinity of the modified polyamide while also improving the flame retardant properties of the modified polyamide, so that the modified polyamide has both good mechanical properties and flame retardant properties. The present invention also introduces long-chain aliphatic amide structural units into the modified polyamide to improve the elongation at break of its fiber. The long-chain polyamide structural units are 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 molecular chain.

[0039] 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, the polyamide monomer, the molecular weight regulator, and water, and performing a prepolymerization reaction to obtain a prepolymer; and performing a polymerization reaction on the prepolymer to obtain the modified polyamide. From the perspective of molecular structure design, the present invention introduces aromatic ring structure compounds to destroy the formation of intermolecular hydrogen bonds and increase the proportion of amorphous regions, thereby improving the drawing properties and mechanical properties of the fiber. The present invention introduces a compound with an aromatic ring structure and a phosphorus-containing group into a polyamide molecular chain through a copolymerization reaction, prepares a modified polyamide with an aromatic ring structure and a phosphorus-containing flame retardant structure in the main chain, and improves the mechanical properties and flame retardant properties of the modified polyamide. Aromatic dibasic acid and phosphorus-containing dibasic acid introduce rigid benzene ring structures into the main chain and side groups of polyamide respectively. The rigid benzene ring structure has a large steric hindrance effect, which destroys the hydrogen bond formation between polyamide molecular chains to a certain extent, reduces the regularity of the polyamide molecular chain, increases the proportion of amorphous regions, and is beneficial to the movement of the polyamide molecular chain, thereby improving the mechanical properties. The present invention utilizes the steric hindrance of the side aromatic ring structure 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 flow properties and spinnability. The present invention introduces a long carbon chain aliphatic amide structure into the modified polyamide in a copolymerization manner to significantly improve the elongation at break of the modified polyamide. 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 molecular chain. DETAILED DESCRIPTION

[0040] The present invention provides a modified polyamide having a structure shown in Formula I:

[0041]

[0042] 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:

[0043] More preferably Here, x is preferably an integer of 4-14, and more preferably an integer of 6-12.

[0044] 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:

[0045] Formula 8, more preferably Here, y is preferably an integer of 4 to 14, and more preferably an integer of 6 to 12.

[0046] 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.

[0047] In the present invention, S is an aliphatic amide structural unit, and the S preferably has a structure shown in Formula 9:

[0048]

[0049] 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.

[0050] 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; 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:

[0051] More preferably

[0052] In the present invention, a is 3 to 6, preferably 4 to 5; b is 1 to 3, preferably 2; c is 2 to 5, preferably 3 to 4; d is 110 to 240, and when P is a polyamide 6 structural unit, d is preferably 220 to 240, and more preferably 230 to 240; when P is a polyamide 66 structural unit, d is preferably 110 to 130, and more preferably 120 to 130; when P is a polyamide 56 structural unit, d is preferably 110 to 130, and more preferably 120 to 130.

[0053] The present invention also provides a method for preparing the modified polyamide described in the above technical solution, comprising the following steps:

[0054] 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;

[0055] 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;

[0056] 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;

[0057] The semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt, polyamide monomer, molecular weight regulator and water are mixed to perform a prepolymerization reaction to obtain a prepolymer;

[0058] The prepolymer is subjected to polymerization reaction to obtain the modified polyamide.

[0059] 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:

[0060]

[0061] Among them, f is preferably any integer from 4 to 14, and more preferably any integer from 6 to 12.

[0062] In the present invention, the first solvent preferably includes water or ethanol, more preferably ethanol.

[0063] 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 mass of the first solvent is preferably 1:3-6, more preferably 1:3-4.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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:

[0069]

[0070] 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.

[0071] In the present invention, the molar ratio of the aliphatic dibasic acid to the third 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 mass of the third solvent is preferably 1:3-6, more preferably 1:3-4.

[0072] 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.

[0073] 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 polyamide monomer, the molecular weight regulator and water to carry out a prepolymerization reaction to obtain a prepolymer. In the present invention, the polyamide monomer preferably includes hexamethylenediamine adipate, caprolactam or pentamethylenediamine adipate, more preferably hexamethylenediamine adipate. 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.

[0074] In the present invention, the molar ratio of the semi-aromatic amide salt to the phosphorus-containing semi-aromatic amide salt is preferably 3-6:1-3, more preferably 3-5:2-3, and most preferably 3:2. In the present invention, the molar ratio of the semi-aromatic amide salt to the aliphatic amide salt is preferably 3-6:2-5, more preferably 3-4:3-4. In the present invention, the molar ratio of the semi-aromatic amide salt to the polyamide monomer is preferably 3-6:110-240. In the present invention, when the polyamide monomer is hexamethylenediamine adipate, the molar ratio of the semi-aromatic amide salt to hexamethylenediamine adipate is preferably 3-6:110-130, more preferably 3-5:120-130; when the polyamide monomer is caprolactam, the molar ratio of the semi-aromatic amide salt to caprolactam is preferably 3-6:220-240, more preferably 3-5:230-240; when the polyamide monomer is pentamethylenediamine adipate, the molar ratio of the semi-aromatic amide salt to pentamethylenediamine adipate is preferably 3-6:110-130, more preferably 3-5:120-130. In the present invention, the mass ratio of the total mass of the aromatic amide salt, the phosphorus-containing semi-aromatic amide salt, the aliphatic amide salt and the polyamide monomer to the molecular weight regulator is preferably 100:0.1-0.2, more preferably 100:0.1-0.15. In the present invention, when the polyamide monomer is hexamethylenediamine adipate, the mass ratio of the total mass of the semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt and hexamethylenediamine adipate to water is preferably 100:80-120, more preferably 100:90-110; in the present invention, when the polyamide monomer is pentamethylenediamine adipate, the mass ratio of the total mass of the semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt and pentamethylenediamine adipate to water is preferably 100:80-120, more preferably 100:90-110; in the present invention, when the polyamide monomer is caprolactam, the mass ratio of the total mass of the semi-aromatic amide salt, phosphorus-containing semi-aromatic amide salt, aliphatic amide salt and caprolactam to water is preferably 100:3-10, more preferably 100:5-8.

[0075] The present invention has no particular limitation on the mixing, as long as the mixing can be uniform.

[0076] In the present invention, the pressure of the prepolymerization reaction is preferably 1.7-2.5 MPa, more preferably 1.8-2.0 MPa; the temperature of the prepolymerization reaction is preferably 200-250°C, more preferably 220-240°C; the time of the prepolymerization reaction is preferably 1-3 hours, more preferably 1-2 hours. 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.

[0077] After obtaining the prepolymer, the present invention performs a polymerization reaction on the prepolymer to obtain the modified polyamide. In the present invention, the vacuum degree of the polymerization reaction is preferably 10 to 800 Pa, more preferably 200 to 700 Pa; the temperature of the polymerization reaction is preferably 260 to 280° C., more preferably 260 to 270° C.; the time of the polymerization reaction is preferably 1 to 3 hours, more preferably 2 hours. In the present invention, the polymerization reaction is preferably accompanied by stirring, and the stirring speed is preferably 20 to 100 r / min, more preferably 50 to 80 r / min.

[0078] The present invention preferably reduces the pressure to normal pressure under the pressure condition of the prepolymerization reaction and then evacuates to the pressure required for the polymerization reaction. In the present invention, the normal pressure is preferably a standard atmospheric pressure. The present invention has no special requirements for the method of reducing the pressure, and the conventional method in the art can be used. In the present invention, the time for reducing the pressure from the prepolymerization reaction to normal pressure is preferably 30 to 120 minutes, more preferably 60 to 90 minutes.

[0079] In the present invention, the product after the polymerization reaction is in a molten state. In the present invention, the process of the prepolymerization reaction and the polymerization reaction is collectively referred to as a copolymerization reaction. The present invention introduces Q structural units, R structural units and S structural units through copolymerization reaction, thereby improving the mechanical properties of the modified polyamide and the flame retardancy of the modified polyamide.

[0080] In the present invention, after the polymerization reaction, the following steps are preferably further included: casting the molten modified polyamide, pelletizing, extracting, and drying in sequence to obtain the modified polyamide.

[0081] The present invention has no special requirements for the casting, pelletizing and extraction, and conventional operations in the art can be used. In the present invention, the drying temperature is preferably 90 to 120° C., more preferably 110 to 120° C.; the drying time is preferably 12 to 48 hours, more preferably 24 to 36 hours.

[0082] 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.

[0083] In the present invention, the breaking strength of the modified polyamide fiber is preferably 8.5 to 9.8 cN / dtex, the breaking elongation is preferably 15 to 30%, and the limiting oxygen index is preferably 25 to 29%.

[0084] 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.

[0085] Preparation of modified polyamide

[0086] Example 1

[0087] 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 50 r / min) for 1 h to obtain hexamethylenediamine terephthalate;

[0088] 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 70° C. (accompanied by stirring at a speed of 60 r / min) for 1 h to obtain hexamethylenediamine DDP salt;

[0089] 5 mol of sebacic acid (1013.75 g) and 5 mol (861.5 g) of decanediamine were dissolved in 5625.9 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;

[0090] 120 mol (31482 g) of hexamethylenediamine adipate, 3 mol (847 g) of hexamethylenediamine terephthalate, 2 mol (564.66 g) of hexamethylenediamine DDP salt, 3 mol (1125.2 g) of decanediamine sebacate, 34019 g of deionized water and 34 g of adipic acid were added to a polymerization kettle, and nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 2.0 MPa. After prepolymerization at 235 ° C for 2 h, the pressure was released to normal pressure (1.01×10 5 After the mixture was stirred for 2 h at 260° C., the mixture was stirred for 2 h at a speed of 50 r / min to obtain a modified polyamide polymer in a molten state.

[0091] The modified polyamide polymer in a molten state is subjected to strip casting, pelletizing, extraction, and drying at 110° C. for 24 hours to obtain modified polyamide 66; the structural formula of the modified polyamide 66 is:

[0092]

[0093] Example 2

[0094] 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 70° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine isophthalate;

[0095] 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;

[0096] Dissolve 5 mol of dodecanedioic acid (1151.35 g) and 5 mol (861.5 g) of decanediamine in 6039 g of ethanol, and perform a third salt-forming reaction at 90° C. (accompanied by stirring at a speed of 50 r / min) for 1 h to obtain decanediamine azelaic acid salt;

[0097] 220 mol (24895.2 g) of caprolactam, 3 mol (1015.32 g) of decanediamine isophthalate, 3 mol (1585.86 g) of decanediamine DPOIA salt, 3 mol (1207.71 g) of decanediamine dodecanedioate, 28862 g of deionized water and 28.8 g of adipic acid were added to a polymerization kettle, and nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 1.9 MPa. After prepolymerization at 235 ° C for 2 h, the pressure was released to normal pressure (1.01×10 5After the mixture was stirred for 2 h at 260° C., the mixture was stirred for 2 h at a speed of 50 r / min to obtain a modified polyamide polymer in a molten state.

[0098] The molten modified polyamide polymer is subjected to strip casting, pelletizing and extraction and then dried at 120° C. for 24 hours to obtain modified polyamide 6. The structural formula of the modified polyamide 6 is:

[0099]

[0100] Example 3

[0101] 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 50 r / min) for 1 h to obtain hexamethylenediamine terephthalate;

[0102] 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;

[0103] Dissolve 5 mol of dodecanedioic acid (1151.35 g) and 5 mol (861.5 g) of decanediamine in 6039 g of ethanol, and perform a third salt-forming reaction at 90° C. (accompanied by stirring at a speed of 50 r / min) for 2 h to obtain decanediamine dodecanedioate;

[0104] 120 mol (31482 g) of pentamethylenediamine adipate, 3 mol (847 g) of hexamethylenediamine terephthalate, 1 mol (386.46 g) of decanediamine CEPPA salt, 3 mol (1207.71 g) of decanediamine dodecanedioate, 33917 g of deionized water and 33 g of adipic acid were added to a polymerization kettle, and nitrogen was introduced to replace the air in the polymerization kettle to maintain a pressure of 2.0 MPa. After prepolymerization at 230 ° C for 2 h, the pressure was released to normal pressure (1.01×10 5 After the mixture was stirred for 2 h at 275° C., the mixture was stirred for 2 h at a speed of 50 r / min to obtain a modified polyamide polymer in a molten state.

[0105] The molten modified polyamide polymer was subjected to strip casting, pelletizing and extraction and then dried at 110° C. for 36 hours to obtain modified polyamide 56. The structural formula of the modified polyamide 56 is:

[0106]

[0107] Preparation of modified polyamide fibers

[0108] Example 4

[0109] The modified polyamide 66 prepared in Example 1 is melt-spinned to obtain modified polyamide 66 fibers;

[0110] The melt spinning temperature was 280°C, the take-up speed was 4000 m / min, and the draft ratio was 5.0.

[0111] Example 5

[0112] The modified polyamide 6 prepared in Example 2 is melt-spinned to obtain modified polyamide 6 fibers;

[0113] The melt spinning temperature was 280° C., the take-up speed was 3500 m / min, and the draft ratio was 5.2.

[0114] Example 6

[0115] The modified polyamide 56 prepared in Example 3 is melt-spinned to obtain modified polyamide 56 fibers;

[0116] The melt spinning temperature was 280° C., the take-up speed was 3000 m / min, and the draft ratio was 5.5.

[0117] The mechanical properties of the modified polyamide fibers prepared in Examples 4 to 6 were tested according to GB / T14344-2008 "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 / T5454-1997 "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.

[0118] Table 1 Mechanical properties and flame retardant properties of modified polyamide fibers prepared in Examples 4 to 6

[0119] Example Breaking strength (cN / dtex) Elongation at break (%) Limiting oxygen index (%) Example 4 9.8 16.2 27.2 Example 5 9.1 25.5 28.6 Example 6 8.6 29.7 25.3

[0120] 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.

[0121] 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 the structure shown in formula I:

2. The method for preparing the modified polyamide for industrial yarn 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 70° 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 6039 g of ethanol, and perform a third salt-forming reaction at 90° C. for 1 h to obtain decanediamine dodecanedioate; 220 mol of caprolactam, 3 mol of decanediamine isophthalate, 3 mol of decanediamine DPOIA salt, 3 mol of decanediamine dodecanedioate, 28862 g of deionized water and 28.8 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 1.9 MPa, and after prepolymerization at 235° C. for 2 hours, the pressure was released to normal pressure within 90 minutes, and then vacuum was evacuated to a vacuum degree of 400 Pa, and polymerization was carried out at 260° C. for 2 hours to obtain a modified polyamide polymer in a molten state; The modified polyamide polymer in a molten state is subjected to strip casting, pelletizing and extraction, and then dried at 120° C. for 24 hours to obtain the modified polyamide for industrial yarn.

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

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