High-strength nylon 56 composite fiber and method for producing the same

Abstract

The application belongs to the technical field of high polymer materials, and discloses a high-strength nylon 56 composite fiber and a preparation method thereof.The preparation method comprises the following steps: mixing nylon 56 salt, a catalyst, an antioxidant, a molecular weight regulator and a solvent, sequentially performing prepolymerization and final polymerization to obtain a nylon 56 polymer; and mixing the nylon 56 polymer with an adhesive, and performing melt spinning to obtain the high-strength nylon 56 composite fiber.The nylon 56 composite fiber prepared by using the scheme has the advantages of high strength, excellent mechanical properties and low yarn breakage rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, and particularly relates to a high-strength nylon 56 composite fiber and a preparation method thereof. BACKGROUND

[0002] Currently, a commonly used spinning method is direct melt spinning, but the direct melt spinning generally has problems such as poor spinnability, high fiber breakage rate and poor mechanical properties of obtained fibers. For nylon 66 (PA66), due to the excessively fast crystallization speed, it is more difficult to control the dyeing uniformity rate when melt spinning, especially when spinning fine denier yarns. Meanwhile, due to the high melting point of PA66 and the reasons of its structure, the thermal stability of PA66 is poor, and under the condition of no oxygen, thermal degradation reaction occurs at a temperature above the melting point, accompanied by crosslinking reaction, which further generates gel, and affects the pipeline transportation in the industrialized production of PA66 and the subsequent spinning work, causing economic losses to enterprises. The above problems make the spinning cost of PA66 high.

[0003] Nylon 56 (PA56) as a good substitute for PA66 can reduce the processing cost, and at present, a large number of enterprises use it. However, due to the short molecular chain of PA56, the phenomenon of broken yarn and unevenness easily occurs in the spinning process, the breaking strength of PA56 is not as good as that of long-chain nylon, the mechanical properties are poor, and the problems of poor strength and toughness generally exist. SUMMARY

[0004] The present application relates to the technical field of high polymer materials, and particularly relates to a high-strength nylon 56 composite fiber and a preparation method thereof.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a high-strength nylon 56 composite fiber, comprising the following steps:

[0007] (1) mixing nylon 56 salt, a catalyst, an antioxidant, a molecular weight regulator and a solvent, and sequentially performing prepolymerization and final polymerization to obtain a nylon 56 polymer;

[0008] (2) mixing the nylon 56 polymer in step (1) with an adhesive to perform melt spinning, and obtaining a high-strength nylon 56 composite fiber;

[0009] In the step (1), the final polymerization is performed under a closed condition;

[0010] The adhesive in step (2) comprises one or more of a biological adhesive, a mineral adhesive and a high molecular polymer;

[0011] The mass of the adhesive in step (2) is 1-10% of the mass of the nylon 56 polymer.

[0012] Preferably, in the preparation method, the catalyst in step (1) comprises one or more of sodium hydroxide, boric acid, toluene diisocyanate, a titanium-based catalyst, and a phosphorus-based catalyst; the titanium-based catalyst comprises one or more of titanium dioxide, titanium chloride, and titanate; the phosphorus-based catalyst comprises one or more of a phosphorus-containing inorganic acid catalyst, a phosphorus-containing alkane catalyst, and a phosphorus-containing metal salt catalyst; the phosphorus-containing inorganic acid catalyst comprises one or more of phosphoric acid, phosphorous acid, and hypophosphorous acid; the phosphorus-containing alkane catalyst comprises one or more of alkyl-substituted phosphoric acid, aryl-substituted phosphoric acid, and aryl-substituted hypophosphorous acid; and the phosphorus-containing metal salt catalyst comprises one or more of sodium hypophosphite, sodium metaphosphate, and sodium pyrophosphate.

[0013] Preferably, in the preparation method, the antioxidant in step (1) comprises one or more of antioxidant 1010, antioxidant DLTDP, antioxidant DSTDP, a phenolic antioxidant, and an amine antioxidant; the phenolic antioxidant is a monophenol and / or a polyphenol; and the amine antioxidant comprises one or more of naphthylamine, diphenylamine, and p-phenylenediamine.

[0014] Preferably, in the preparation method, the molecular weight regulator in step (1) is phosphorous acid and / or an organic acid; the organic acid is a dibasic acid and / or a monobasic aromatic acid; the dibasic acid comprises one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, dodecanedioic acid, and tridecanedioic acid; and the monobasic aromatic acid is benzoic acid and / or phenylacetic acid.

[0015] Preferably, in the preparation method, in step (1), the mass of the nylon 56 salt is 30-80% of the sum of the mass of the nylon 56 salt and the solvent; and the mass of the catalyst, the antioxidant, and the molecular weight regulator independently is 0.01-0.5% of the sum of the mass of the nylon 56 salt and the solvent.

[0016] Preferably, in the preparation method, the temperature of the prepolymerization reaction in step (1) is 120-200°C, the pressure is 0.5-3 MPa, and the time is 0.5-8 h.

[0017] Preferably, in the preparation method, in step (1), the temperature of the final polymerization reaction is 220-290°C, and the time is 30-240 min; and the final polymerization reaction further comprises vacuuming, and the time of the vacuuming is 10-60 min.

[0018] Preferably, in the preparation method, in step (2), the biological adhesive is animal glue and / or rosin, the animal glue is shellac and / or skin glue; the mineral adhesive comprises one or more of asphalt, geocare adhesive and sulfur adhesive; and the high molecular polymer comprises one or more of nylon 510, nylon 512 and nylon 612.

[0019] Preferably, in the preparation method, the temperature for melt spinning in step (2) is 250-290 DEG C, and the draw ratio is 1.5-4 times.

[0020] The application further provides a high-strength nylon 56 composite fiber prepared by the preparation method.

[0021] According to the technical scheme, compared with the prior art, the application has the following beneficial effects:

[0022] (1) In the technical scheme, the catalyst is conducive to the polymerization reaction, can accelerate the formation of intermolecular hydrogen bonds, and is conducive to the growth of nylon molecular chains; the antioxidant can improve the yellowing phenomenon of the polymer or fiber due to oxidation; the molecular weight regulator can act as an initiator to initiate the polymerization reaction and control the molecular weight of the nylon; the prepolymerization reaction can first cause the dehydration condensation reaction of the nylon 56 salt to form a low-molecular-weight prepolymer, and then discharge water vapor and some by-products out of the kettle; the final polymerization reaction mainly performs a polycondensation reaction on the nylon 56 salt, and by optimizing the final polymerization process conditions (temperature and time), the molecular weight can be narrowed, the polymer viscosity can be increased, and thus the strength and mechanical properties of the nylon 56 composite fiber can be increased; and the main purpose of adding the adhesive is to add a material (for example, long-chain nylon) having a bonding effect (for example, long-chain nylon, because the mechanical properties such as tensile strength and breaking rate of long-chain nylon are better than those of nylon 56), which can reduce the yarn breakage rate of the nylon 56 polymer during the spinning and drawing process and improve the mechanical properties of the nylon 56 composite fiber. Therefore, by adopting the scheme, the adhesive and the nylon 56 polymer are melt spun together, and the prepared nylon 56 composite fiber has the advantages of high strength, excellent mechanical properties and low yarn breakage rate.

[0023] (2) The improvement idea of the application for the nylon 56 salt not only lies in the optimization of a single material, but also can be extended to other nylon salts, and has broad development potential and application prospect. DETAILED DESCRIPTION

[0024] The application provides a preparation method of a high-strength nylon 56 composite fiber, which comprises the following steps:

[0025] (1) mixing the nylon 56 salt, the catalyst, the antioxidant, the molecular weight regulator and the solvent, and sequentially performing prepolymerization and final polymerization to obtain a nylon 56 polymer;

[0026] (2) mixing the nylon 56 polymer of step (1) with an adhesive to melt-spinning, obtaining high-strength nylon 56 composite fiber;

[0027] wherein the final polymerization of step (1) is carried out under airtight condition;

[0028] The adhesive of step (2) comprises one or more of biological adhesive, mineral adhesive and high molecular polymer;

[0029] The mass of the adhesive of step (2) is 1-10% of the mass of the nylon 56 polymer.

[0030] In the present application, the catalyst of step (1) preferably comprises one or more of sodium hydroxide, boric acid, toluene diisocyanate, titanium-based catalyst and phosphorus-based catalyst, further preferably comprises sodium hydroxide, boric acid, toluene diisocyanate, titanium-based catalyst or phosphorus-based catalyst, and more preferably is phosphorus-based catalyst.

[0031] In the present application, the titanium-based catalyst preferably comprises one or more of titanium dioxide, titanium chloride and titanate, further preferably is titanium dioxide or titanate, and more preferably is titanium dioxide.

[0032] In the present application, the phosphorus-based catalyst preferably comprises one or more of phosphorus-containing inorganic acid catalyst, phosphorus-containing alkane catalyst and phosphorus-containing metal salt catalyst, further preferably is phosphorus-containing inorganic acid catalyst, phosphorus-containing alkane catalyst or phosphorus-containing metal salt catalyst, and more preferably is phosphorus-containing metal salt catalyst.

[0033] In the present application, the phosphorus-containing inorganic acid catalyst preferably comprises one or more of phosphoric acid, phosphorous acid and hypophosphorous acid, further preferably is phosphoric acid, phosphorous acid or hypophosphorous acid, and more preferably is hypophosphorous acid.

[0034] In the present application, the phosphorus-containing alkane catalyst preferably comprises one or more of alkyl-substituted phosphoric acid, aryl-substituted phosphoric acid and aryl-substituted hypophosphorous acid, further preferably is alkyl-substituted phosphoric acid, aryl-substituted phosphoric acid or aryl-substituted hypophosphorous acid, and more preferably is aryl-substituted hypophosphorous acid.

[0035] In the present application, the phosphorus-containing metal salt catalyst preferably comprises one or more of sodium hypophosphite, sodium metaphosphate and sodium pyrophosphate, further preferably is sodium hypophosphite or sodium metaphosphate, and more preferably is sodium hypophosphite.

[0036] In the present application, the antioxidant of step (1) preferably comprises one or more of antioxidant 1010 (butylated triphenyl phosphate), antioxidant DLTDP (dilauryl thiodipropionate), antioxidant DSTDP (distearyl thiodipropionate), a phenolic antioxidant, and an amine antioxidant, further preferably comprises one or more of antioxidant 1010, antioxidant DLTDP, and antioxidant DSTDP, more preferably is antioxidant 1010.

[0037] In the present application, the phenolic antioxidant is preferably a monophenol and / or a polyphenol, further preferably a polyphenol; the polyphenol is preferably hydroquinone and / or thiodiphenol, further preferably thiodiphenol.

[0038] In the present application, the amine antioxidant preferably comprises one or more of naphthylamine, diphenylamine, and p-phenylenediamine, further preferably is naphthylamine, diphenylamine, or p-phenylenediamine, more preferably is p-phenylenediamine.

[0039] In the present application, the molecular weight regulator of step (1) is preferably phosphorous acid and / or an organic acid, further preferably phosphorous acid or an organic acid, more preferably phosphorous acid.

[0040] In the present application, the organic acid is preferably a dibasic acid and / or a monobasic aromatic acid, further preferably a dibasic acid.

[0041] In the present application, the dibasic acid preferably comprises one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, dodecanedioic acid, and tridecanedioic acid, further preferably oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, or benzoic acid, more preferably adipic acid.

[0042] In the present application, the aromatic acid preferably comprises benzoic acid and / or phenylacetic acid, further preferably benzoic acid.

[0043] In the present application, the solvent of step (1) is preferably water.

[0044] In the present application, the mass of the nylon 56 salt of step (1) is preferably 30-80% of the sum of the mass of the nylon 56 salt and the mass of the solvent, further preferably 50-70%, more preferably 60%.

[0045] In the present application, the mass of the catalyst of step (1) is preferably 0.01-0.5% of the sum of the mass of the nylon 56 salt and the mass of the solvent, further preferably 0.2-0.5%, more preferably 0.3%.

[0046] In the present application, the mass of the antioxidant in step (1) is preferably 0.01 to 0.5% of the total mass of the nylon 56 salt and the solvent, further preferably 0.05 to 0.2%, and more preferably 0.1%.

[0047] In the present application, the mass of the molecular weight regulator in step (1) is preferably 0.01 to 0.5% of the total mass of the nylon 56 salt and the solvent, further preferably 0.1 to 0.3%, and more preferably 0.15%.

[0048] In the present application, the temperature of the prepolymerization in step (1) is preferably 120 to 200°C, further preferably 160 to 200°C, and more preferably 200°C; the pressure is preferably 0.5 to 3 MPa, further preferably 0.5 to 2 MPa, and more preferably 0.8 to 1.5 MPa; and the time is preferably 0.5 to 8 h, further preferably 1 to 3 h, and more preferably 2 h.

[0049] In the present application, the prepolymerization in step (1) is preferably further followed by reduction to normal pressure. The time for the reduction to normal pressure is preferably 0.1 to 3 h, further preferably 1 to 2 h, and more preferably 1.5 h.

[0050] In the present application, the temperature of the final polymerization in step (1) is preferably 220 to 290°C, further preferably 240 to 280°C, and more preferably 260°C; the time is preferably 30 to 240 min, further preferably 45 to 90 min, and more preferably 60 min; and the pressure is preferably normal pressure.

[0051] In the present application, the final polymerization in step (1) is preferably further followed by vacuuming. The time for the vacuuming is preferably 10 to 60 min, further preferably 10 to 30 min, and more preferably 20 min.

[0052] In the present application, the adhesive in step (2) includes one or more of a biological adhesive, a mineral adhesive, and a high-molecular polymer, and is preferably a biological adhesive, a mineral adhesive, or a high-molecular polymer, and further preferably a high-molecular polymer.

[0053] In the present application, the biological adhesive is preferably animal glue and / or rosin, and further preferably animal glue.

[0054] In the present application, the animal glue is preferably shellac and / or skin glue, and further preferably shellac.

[0055] In the present application, the mineral adhesive preferably includes one or more of asphalt, geoclay adhesive, and sulfur adhesive, and is further preferably asphalt or sulfur adhesive, and more preferably asphalt.

[0056] In the present application, the high molecular polymer preferably comprises one or more of nylon 510, nylon 512 and nylon 612, further preferably nylon 510, nylon 512 or nylon 612, and further preferably nylon 510.

[0057] In the present application, the mass ratio of the adhesive to the nylon 56 polymer in step (2) is 1-10%, preferably 5-10%, and further preferably 10%.

[0058] In the present application, before mixing the nylon 56 polymer and the adhesive in step (2), the nylon 56 polymer and the adhesive are preferably pulverized. The present application does not limit the size of the pulverization, which can be achieved by means well known to those skilled in the art.

[0059] In the present application, the temperature for melt spinning in step (2) is preferably 250-290°C, further preferably 260-280°C, and more preferably 270°C; and the draw ratio is preferably 1.5-4, further preferably 2-3, and more preferably 2.

[0060] In the present application, the normal pressure is one atmosphere, unless otherwise specified.

[0061] The present application also provides a high-strength nylon 56 composite fiber prepared by the preparation method.

[0062] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0063] Embodiment 1

[0064] The present embodiment provides a preparation method of a high-strength nylon 56 composite fiber, comprising the following steps:

[0065] (1) 160.18 g of nylon 56 salt, 106.79 g of deionized water, 0.8009 g of sodium hypophosphite, 0.2670 g of antioxidant 1010 and 0.4005 g of phosphorous acid are added into a reaction kettle, and pre-polymerization is carried out at 200°C and 0.8-1.5 MPa for 2 h; after the pre-polymerization is completed, the exhaust valve is opened to slowly exhaust for 1.5 h to normal pressure, and the temperature is raised to 260°C for final polymerization under the condition of closed normal pressure for 60 min; after the final polymerization is completed, vacuum is applied for 20 min, and the material is extruded by opening the discharge valve, to obtain a nylon 56 polymer, and the molecular weight Mn of the nylon 56 polymer is 25543.

[0066] (2) 50 g of the nylon 56 polymer is crushed to 1 mm together with 0.5 g of the long-chain nylon 510, and mixed uniformly, and then put into a melt spinning machine to spin, the spinning temperature is 270°C, the draw ratio is 2 times, and after winding, high-strength nylon 56 composite fibers are obtained.

[0067] Example 2

[0068] (1) 160.23 g of nylon 56 salt, 106.82 g of deionized water, 0.8012 g of sodium hypophosphite, 0.2671 g of antioxidant 1010, and 0.4005 g of phosphorous acid are added into a reaction kettle, and pre-polymerized at 200°C and 0.8-1.5 MPa for 2 h; after pre-polymerization is completed, the exhaust valve is opened to slowly exhaust for 1.5 h to normal pressure, and heated to 260°C to perform final polymerization under the condition of closed normal pressure for 60 min; after the final polymerization is completed, vacuum is extracted for 20 min, the discharge valve is opened to pressurize and extrude the material, and nylon 56 polymer is obtained, the molecular weight Mn of the nylon 56 polymer is 26623;

[0069] (2) 50 g of the nylon 56 polymer is crushed to 1 mm together with 2.5 g of the long-chain nylon 510, and mixed uniformly, and then put into a melt spinning machine to spin, the spinning temperature is 270°C, the draw ratio is 2 times, and after winding, high-strength nylon 56 composite fibers are obtained.

[0070] Example 3

[0071] (1) 160.34 g of nylon 56 salt, 106.89 g of deionized water, 0.8017 g of sodium hypophosphite, 0.2673 g of antioxidant 1010, and 0.4008 g of phosphorous acid are added into a reaction kettle, and pre-polymerized at 200°C and 0.8-1.5 MPa for 2 h; after pre-polymerization is completed, the exhaust valve is opened to slowly exhaust for 1.5 h to normal pressure, and heated to 260°C to perform final polymerization under the condition of closed normal pressure for 60 min; after the final polymerization is completed, vacuum is extracted for 20 min, the discharge valve is opened to pressurize and extrude the material, and nylon 56 polymer is obtained, the molecular weight Mn of the nylon 56 polymer is 26031;

[0072] (2) 50 g of the nylon 56 polymer is crushed to 1 mm together with 5 g of the long-chain nylon 510, and mixed uniformly, and then put into a melt spinning machine to spin, the spinning temperature is 270°C, the draw ratio is 2 times, and after winding, high-strength nylon 56 composite fibers are obtained.

[0073] Example 4

[0074] The embodiment provides a preparation method of high-strength nylon 56 composite fibers, comprising the following steps:

[0075] (1) Take 160.94 g of nylon 56 salt, 107.29 g of deionized water, 0.8047 g of sodium hypophosphite, 0.2682 g of antioxidant 1010, and 0.4023 g of phosphorous acid into a reaction kettle, and pre-polymerize at 200°C and 0.8-1.5 MPa for 2 h. After pre-polymerization, slowly release the gas for 1.5 h to normal pressure by opening the gas valve, and then raise the temperature to 260°C to perform final polymerization under the condition of closed normal pressure for 60 min. After the final polymerization, vacuumize for 20 min, open the discharge valve to pressurize and extrude the material, and obtain nylon 56 polymer. The molecular weight of the nylon 56 polymer is Mn26410.

[0076] (2) Crush 50 g of the nylon 56 polymer and 5 g of long-chain nylon 512 to 1 mm and mix uniformly, and then put them into a melt spinning machine to perform spinning. The spinning temperature is 270°C, and the draw ratio is 2 times. After winding, high-strength nylon 56 composite fibers are obtained.

[0077] Example 5

[0078] The embodiment provides a preparation method of high-strength nylon 56 composite fibers, which comprises the following steps:

[0079] (1) Take 160.02 g of nylon 56 salt, 106.68 g of deionized water, 0.8001 g of sodium hypophosphite, 0.2667 g of antioxidant 1010, and 0.4000 g of phosphorous acid into a reaction kettle, and pre-polymerize at 200°C and 0.8-1.5 MPa for 2 h. After pre-polymerization, slowly release the gas for 1.5 h to normal pressure by opening the gas valve, and then raise the temperature to 260°C to perform final polymerization under the condition of closed normal pressure for 60 min. After the final polymerization, vacuumize for 20 min, open the discharge valve to pressurize and extrude the material, and obtain nylon 56 polymer. The molecular weight of the nylon 56 polymer is Mn26848.

[0080] (2) Crush 50 g of the nylon 56 polymer and 5 g of long-chain nylon 612 to 1 mm and mix uniformly, and then put them into a melt spinning machine to perform spinning. The spinning temperature is 270°C, and the draw ratio is 2 times. After winding, high-strength nylon 56 composite fibers are obtained.

[0081] Comparative Example 1

[0082] The comparative example provides a preparation method of nylon 56 fibers, which comprises the following steps:

[0083] (1) Take 160.10 g of nylon 56 salt, 106.73 g of deionized water, 0.8005 g of sodium hypophosphite, 0.2668 g of antioxidant 1010, and 0.4002 g of phosphorous acid into a reaction kettle, and pre-polymerize at 200°C and 0.8-1.5 MPa for 2 h. After pre-polymerization, slowly release the gas for 1.5 h to normal pressure by opening the gas valve, and then raise the temperature to 260°C to perform final polymerization under the condition of closed normal pressure for 60 min. After the final polymerization, vacuumize for 20 min, open the discharge valve to pressurize and extrude the material, and obtain nylon 56 polymer. The molecular weight Mn of the nylon 56 polymer is 25436.

[0084] (2) Crush the nylon 56 polymer to 1 mm, and then put it into a melt spinning machine to perform spinning. The spinning temperature is 270°C, and the draw ratio is 2 times. After winding, nylon 56 fiber is obtained.

[0085] Comparative Example 2

[0086] The present comparative example provides a preparation method of nylon 56 fiber, comprising the following steps:

[0087] (1) Take 160.26 g of nylon 56 salt, 106.84 g of deionized water, 0.8013 g of sodium hypophosphite, 0.2671 g of antioxidant 1010, and 0.4007 g of phosphorous acid into a reaction kettle, and pre-polymerize at 200°C and 0.8-1.5 MPa for 2 h. After pre-polymerization, slowly release the gas for 1.5 h to normal pressure by opening the gas valve, and then raise the temperature to 260°C to perform final polymerization under the condition of closed normal pressure for 60 min. After the final polymerization, vacuumize for 20 min, open the discharge valve to pressurize and extrude the material, and obtain nylon 56 polymer. The molecular weight Mn of the nylon 56 polymer is 26475.

[0088] (2) Crush the nylon 56 polymer to 1 mm, and then put it into a melt spinning machine to perform spinning. The spinning temperature is 270°C, and the draw ratio is 2 times. After winding, nylon 56 fiber is obtained.

[0089] Comparative Example 3

[0090] The present comparative example provides a preparation method of nylon 56 fiber, comprising the following steps:

[0091] (1) Take 160.14 g of nylon 56 salt, 106.76 g of deionized water, 0.8007 g of sodium hypophosphite, 0.2669 g of antioxidant 1010, and 0.4004 g of phosphorous acid into a reaction kettle, and pre-polymerize at 200℃ under 0.8-1.5 MPa for 2 h; after pre-polymerization is completed, slowly release the gas for 1.5 h to normal pressure by opening the gas release valve, and then raise the temperature to 260℃ to perform final polymerization under the condition of closed normal pressure for 60 min; after the final polymerization is completed, open the discharge valve to pressurize and extrude the material after vacuumizing for 20 min, to obtain a nylon 56 polymer, and the molecular weight Mn of the nylon 56 polymer is 25272;

[0092] (2) Crush the nylon 56 polymer to 1 mm, and then put it into a melt spinning machine to perform spinning, the spinning temperature is 260℃, the draw ratio is 2 times, and after winding, a nylon 56 fiber is obtained.

[0093] Comparative Example 4

[0094] The present comparative example provides a preparation method of a nylon 56 composite fiber, comprising the following steps:

[0095] (1) Take 160.05 g of nylon 56 salt, 106.70 g of deionized water, 0.8003 g of sodium hypophosphite, 0.2668 g of antioxidant 1010, and 0.4001 g of phosphorous acid into a reaction kettle, and pre-polymerize at 200℃ under 0.8-1.5 MPa for 2 h; after pre-polymerization is completed, slowly release the gas for 1.5 h to normal pressure by opening the gas release valve, and then raise the temperature to 260℃ to perform final polymerization under the condition of closed normal pressure for 60 min; after the final polymerization is completed, open the discharge valve to pressurize and extrude the material after vacuumizing for 20 min, to obtain a nylon 56 polymer, and the molecular weight Mn of the nylon 56 polymer is 25304;

[0096] (2) Crush 50 g of the nylon 56 polymer and 10 g of long-chain nylon 510 to 1 mm and mix uniformly, and then put it into a melt spinning machine to perform spinning, the spinning temperature is 270℃, the draw ratio is 2 times, and after winding, a high-strength nylon 56 composite fiber is obtained.

[0097] Test Example 1

[0098] (1) The relative viscosity of the fiber product obtained in Examples 1-5 and Comparative Examples 1-4 is measured in a 96% concentrated sulfuric acid solution at 25±0.01℃ using an Ubbelohde viscometer, and the concentration is 0.01 g / mL;

[0099] (2) The fineness of the fiber obtained in Examples 1-5 and Comparative Examples 1-4 is determined according to the method of GB / T 14343-2003;

[0100] (3) The breaking strength and elongation at break of the fiber obtained in Examples 1-5 and Comparative Examples 1-4 were determined according to the method of GB / T 14344-2008.

[0101] The results of Test Example 1 are shown in Table 1.

[0102] Table 1. Results of Test Example 1

[0103]

[0104] As shown in Table 1, the addition of long-chain high-molecular nylon polymer increases the breaking strength and elongation at break of the nylon 56 fiber, and the mechanical properties thereof are superior to those of pure nylon 56 fiber without the addition of long-chain nylon. The nylon 56 composite fiber obtained by adding long-chain high-molecular nylon polymer PA510 has higher strength and is more suitable for PA56 spinning. However, when the addition amount of long-chain high-molecular nylon polymer is higher than 10 wt% of the nylon 56 polymer, the mechanical properties such as the strength and elongation at break of the nylon 56 composite fiber are not as good as those when the addition amount is 1-10%, because too much long-chain high-molecular nylon polymer cannot be well fused together after melting, resulting in layering and poor mechanical properties.

[0105] The above description is only preferred embodiments of the present application, and it should be pointed out that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing high-strength nylon 56 composite fiber, characterized in that, Includes the following steps: (1) Nylon 56 salt, catalyst, antioxidant, molecular weight regulator and solvent are mixed and subjected to prepolymerization reaction and final polymerization reaction in sequence to obtain Nylon 56 polymer; (2) The nylon 56 polymer described in step (1) is mixed with an adhesive and melt-spun to obtain high-strength nylon 56 composite fiber; Wherein, the molecular weight regulator in step (1) is phosphorous acid; In step (1), the mass of the catalyst, the antioxidant, and the molecular weight regulator is independently 0.01~0.5% of the sum of the masses of nylon 56 salt and solvent; In step (1), the mass of the nylon 56 salt is 30-80% of the sum of the masses of the nylon 56 salt and the solvent; The temperature of the prepolymerization reaction in step (1) is 120~200℃, the pressure is 0.5~3MPa, and the time is 0.5~8h; The final polymerization reaction described in step (1) is carried out under closed conditions; The adhesive used in step (2) is nylon 510; The mass of the adhesive in step (2) is 10% of the mass of the nylon 56 polymer.

2. The preparation method according to claim 1, characterized in that, The catalyst in step (1) includes one or more of sodium hydroxide, boric acid, toluene diisocyanate, titanium-based catalysts, and phosphorus-based catalysts; the titanium-based catalyst includes one or more of titanium dioxide, titanium chloride, and titanate; the phosphorus-based catalyst includes one or more of phosphorus-containing inorganic acid catalysts, phosphorus-containing alkyl catalysts, and phosphorus-containing metal salt catalysts; the phosphorus-containing inorganic acid catalyst includes one or two of phosphoric acid and hypophosphoric acid; the phosphorus-containing alkyl catalyst includes one or more of alkyl-substituted phosphoric acid, aryl-substituted phosphoric acid, and aryl-substituted hypophosphoric acid; the phosphorus-containing metal salt catalyst includes one or more of sodium hypophosphite, sodium metaphosphate, and sodium pyrophosphate.

3. The preparation method according to claim 1 or 2, characterized in that, The antioxidants in step (1) include one or more of antioxidant 1010, antioxidant DLTDP, antioxidant DSTDP, phenolic antioxidants and amine antioxidants; the phenolic antioxidants are monophenols and / or polyphenols; the amine antioxidants include one or more of naphthylamine, diphenylamine and p-phenylenediamine.

4. The preparation method according to claim 1, characterized in that, In step (1), the temperature of the final polymerization reaction is 220~290℃ and the time is 30~240min; after the final polymerization reaction, vacuuming is also included, and the vacuuming time is 10~60min.

5. The preparation method according to claim 1, characterized in that, The temperature of melt spinning in step (2) is 250~290℃ and the draw ratio is 1.5~4 times.

6. High-strength nylon 56 composite fiber prepared by the preparation method according to any one of claims 1 to 5.

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