A high-strength, low-shrinkage PA6 industrial yarn and its preparation method

Abstract

This invention discloses a method for preparing high-strength, low-shrinkage PA6 industrial yarn, comprising: premixing PA6A (relative viscosity 2.4-2.8, mass fraction 80-99%) and PA6B (relative viscosity 3.4-4.0, mass fraction 1-20%) at high speed with stirring; drying to remove moisture to obtain PA6 spinning particles; adding a high-temperature antioxidant to the PA6 spinning particles; preparing PA6 nascent fibers using a melt spinning machine; coating the fiber surface with an antioxidant oil; and then preparing high-strength, low-shrinkage PA6 industrial yarn using a subsequent drawing system with multi-stage drawing and high-temperature tension setting technology. This invention utilizes a small amount of high-molecular-weight PA6B molecular chains as binding chains to induce crystallization and orientation of conventional molecular weight PA6A molecules, improving the condensed-state structure of the fiber and enhancing the mechanical properties of the PA6 industrial yarn.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of PA6 industrial yarn preparation, and particularly relates to a high-strength and low-shrinkage PA6 industrial yarn and a preparation method thereof. BACKGROUND

[0002] Polyamide 6 (PA6) is a linear semi-crystalline aliphatic thermoplastic engineering plastic, which has excellent properties such as light weight, high strength, wear resistance, fatigue resistance, resistance to weak acid, weak base and some organic solvents, and corrosion resistance. PA6 is easy to process and can be made into engineering plastics, films and fibers through processes such as injection molding, blow molding, extrusion, film pressing and melt spinning, so it can not only be used as a reinforcing material, but also can replace steel, copper and other metals, and can be blended with other fibers to make cord, conveyor belt and parachute with high wear resistance, and has a wide application in the fields of textile and garment, industrial textiles and national defense and military industry. Therefore, a high-strength and low-shrinkage PA6 industrial yarn with simple process is developed to be better applied in various fields, and is concerned by researchers at home and abroad.

[0003] The invention patent with the Chinese patent number CN115559012A discloses a preparation method of high-strength PA6 industrial yarn. The patent introduces nylon 5T structural units into nylon 6 for copolymerization and modification, and then the copolyamide chips are extracted and dried, and then melt spinning is carried out, and then the high-strength PA6 industrial yarn is obtained after side blowing, oiling, drawing and winding. The melting point of the PA6 / 5T copolyamide obtained by the method is significantly higher than that of PA6, which increases the energy consumption and production cost of the spinning process.

[0004] The invention patent with the Chinese patent number CN114990729A discloses a wear-resistant nylon yarn and a preparation method thereof. The patent uniformly mixes nylon resin, wear-resistant agent, antioxidant, lubricant and modified reinforcing agent, granulates the nylon through a double-screw extruder and a granulator, and then spins to obtain a nylon yarn with good wear resistance and high mechanical strength. The method needs additional extrusion granulation, which makes the preparation process complex and the production cost high, and the mixing of inorganic fillers in high-viscosity materials also easily causes problems such as agglomeration and gelation, which greatly affects the spinning temperature and component pressure.

[0005] With the development of society, general materials have been unable to meet the demand, and each field has put forward higher requirements for materials. PA6 fiber has outstanding mechanical properties, and is indispensable in the field of textile and garment, and is widely used in many fields, especially in the field of industrial yarn. The PA6 industrial yarn in the prior art has insufficient strength, a complex preparation process and high production cost, therefore, developing high-strength, high-temperature antioxidant oil agent, and easy-to-process high-strength low-shrinkage PA6 industrial yarn, which is better applied in the fields of national defense and military industry, transportation, etc., has become an important research topic. SUMMARY

[0006] Therefore, the application provides a high-strength low-shrinkage PA6 industrial yarn and a preparation method thereof to solve the problems of insufficient strength, complex preparation process and high production cost of the PA6 industrial yarn in the prior art. To achieve the above-mentioned purpose, the application provides a preparation method of high-strength low-shrinkage PA6 industrial yarn, which comprises the following steps:

[0007] S1: stirring and premixing PA6A with low relative viscosity and PA6B with high relative viscosity, drying to remove water, and obtaining PA6 spinning particles;

[0008] S2: adding an antioxidant above 300 DEG C to the PA6 spinning particles prepared in step S1, preparing PA6 primary fibers by a melt spinning machine, coating the surface of the fibers with an antioxidant oil agent, and then preparing high-strength low-shrinkage PA6 industrial yarn by a subsequent drawing system, using multi-stage drawing and high-temperature tension setting technology.

[0009] As a further preferred technical solution of the application, in step S1, the relative viscosity of PA6A is 2.4-2.8, the mass fraction is 80-99%, the relative viscosity of PA6B is 3.4-4.0, and the mass fraction is 1-20%.

[0010] As a further preferred technical solution of the application, in step S2, the mass fraction of the antioxidant above 300 DEG C is 0.1-1.0%.

[0011] As a further preferred technical solution of the application, in step S2, the antioxidant oil agent is an oil-soluble high-temperature antioxidant with a mass fraction of 3.0-5.0% added to the base oil agent.

[0012] As a further preferred technical solution of the application, in step S2, the multi-stage drawing technology is a one-stage drawing ratio, a two-stage drawing temperature, and a two-stage drawing ratio multiple coupling regulation technology, wherein the one-stage drawing ratio is 2.5-4.5, the two-stage drawing temperature is 140-180 DEG C, and the two-stage drawing ratio is 1.1-1.5.

[0013] As a further preferred technical solution of the present application, in step S2, the high-temperature tension setting technology is a heat setting temperature and heat setting tension coupling regulation technology, wherein the heat setting temperature is 200-225 DEG C, and the difference between the setting roller speed and the tension roller speed is 1-5%.

[0014] According to another aspect of the present application, the present application also provides a high-strength and low-shrinkage PA6 industrial yarn prepared by the above-mentioned preparation method of high-strength and low-shrinkage PA6 industrial yarn, and has a fineness of 80 dtex, a tensile strength of 7.05-10.32 cN / dtex, and an elongation at break of 13-30%.

[0015] Compared with the closest prior art, the technical solution provided by the present application has the following beneficial effects:

[0016] 1. The preparation method of the present application uses a small amount of high-molecular-weight PA6B molecular chain as a constraint chain to induce the crystallization and orientation of conventional-molecular-weight PA6A, improves the condensed state structure of the fiber, and further improves the mechanical properties of the PA6 industrial yarn;

[0017] 2. The preparation method of the present application balances the mechanical properties and spinnability of high-molecular-weight PA6B and conventional-molecular-weight PA6A by regulating the ratio of the two, realizes complementary advantages, and thus improves the tensile strength and spinnability of the multifilament;

[0018] 3. The preparation method provided by the present application avoids the energy consumption and inconvenience of recycling caused by repeated granulation of organic or inorganic additives, and is simple in process and cost-saving;

[0019] 4. The preparation method of the present application prepares a high-strength and low-shrinkage PA6 industrial yarn with excellent mechanical properties, which can be widely used in industrial textiles, national defense and military industry, and transportation and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a physical map of the high-strength and low-shrinkage PA6 industrial yarn prepared in Example 4 of the present application;

[0021] Figure 2 It is a mechanical property comparison chart of the PA6 industrial yarn obtained when the total draw ratio is different when Example 3 is taken as the experimental object;

[0022] Figure 3 It is a stress-strain curve chart of the high-strength and low-shrinkage PA6 industrial yarn prepared in Examples 1, 2 and 3 of the present application;

[0023] Figure 4 It is a mechanical property chart of the high-strength and low-shrinkage PA6 industrial yarn prepared in Examples 1-4 and Comparative Examples 1-3 of the present application. DETAILED DESCRIPTION

[0024] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0025] Please refer to Figures 1 to 4 The present application provides a preparation method of high-strength and low-shrinkage PA6 industrial yarn, specifically comprising the following steps:

[0026] S1: PA6A with a relative viscosity of 2.4-2.8 and a mass fraction of 80-99% and PA6B with a relative viscosity of 3.4-4.0 and a mass fraction of 1-20% are stirred and premixed, and then dried to remove water to obtain PA6 spinning particles;

[0027] S2: The PA6 spinning particles prepared in step S1 are added with 0.1-1.0% of an antioxidant with a temperature of above 300 DEG C, and then passed through a melt spinning machine to prepare PA6 primary fibers, and the surface of the fibers is coated with an oil agent with an oil-soluble high-temperature antioxidant with a mass fraction of 3.0-5.0%; then the fibers are passed through a subsequent drawing system, and a multi-stage drawing and high-temperature tension setting technology is used, wherein the primary drawing ratio is 2.5-4.5, the secondary drawing temperature is 140-180 DEG C, the secondary drawing ratio is 1.1-1.5, the heat setting temperature is 200-225 DEG C, and the difference between the setting roller speed and the tension roller speed is 1-5%, to prepare high-strength and low-shrinkage PA6 industrial yarn.

[0028] The PA6A and the PA6B in the present application are PA6 materials with different relative viscosities and different use ratios, and the high-strength and low-shrinkage PA6 industrial yarn prepared by the above method has a fineness of 80 dtex, a tensile strength of 7.05-10.32 cN / dtex, and an elongation at break of 13-30%, and the excellent mechanical properties can be widely used in industrial textiles, national defense and military industry, and transportation, etc.

[0029] The high molecular weight PA6 industrial yarn has high tensile strength, but poor spinnability, and the conventional molecular weight PA6 industrial yarn has good spinnability, but insufficient mechanical properties. The application utilizes high molecular weight PA6 to induce the orientation and crystallization of conventional molecular weight PA6 to improve the performance of PA6 industrial yarn, and a small amount of high molecular weight PA6B molecular chain is used as a constraint chain to induce the crystallization and orientation of conventional molecular weight PA6A, so as to improve the condensed state structure of the fiber and the mechanical properties of the PA6 industrial yarn. By adjusting the ratio of high molecular weight PA6B and conventional molecular weight PA6A, the mechanical properties and spinnability of the two are balanced, the optimal ratio scheme is found, the advantages are complementary, and the tensile strength and spinnability of the industrial yarn are improved. The preparation method avoids the energy consumption and inconvenience of recycling caused by repeated granulation of organic or inorganic additives, and has simple process and cost saving.

[0030] In order for those skilled in the art to better understand and implement the technical solutions of the application, the above preparation method and the corresponding process parameters provided in Table 1 are used to propose Examples 1-4 and Comparative Examples 1-3.

[0031]

[0032]

[0033] Table 1 Process parameter table of Examples 1-4 and Comparative Examples 1-3

[0034] The high-strength low-shrinkage PA6 industrial yarn prepared by the above method has the mechanical property indexes shown in Table 2.

[0035]

[0036]

[0037] Table 2 Performance index table of high-strength low-shrinkage PA6 industrial yarn prepared in Examples 1-4 and Comparative Examples 1-3

[0038] As can be seen from Table 2, the high-strength low-shrinkage PA6 industrial yarn prepared in Examples 1-4 all has good tensile strength, and the tensile strength of the high-strength low-shrinkage PA6 industrial yarn prepared in Examples 1-4 is 9.13-10.32 cN / dtex. Figure 1 The stress-strain curves of the prepared high-strength low-shrinkage PA6 industrial yarn are shown in Figure 2 .

[0039] Taking Example 3 as the experimental object, the total draft ratio of the fiber is changed under the condition that other parameters remain unchanged, and the specific reference is shown in Table 3. Figure 3 The breaking strength of the PA6 industrial yarn increases with the increase of the total draft ratio, and the mechanical strength is between 9.13-10.32 cN / dtex when the total draft ratio is in the range of 4.50-4.89, which shows good tensile properties.

[0040] Referring to Tables 1 and 2, the mass fraction of the raw materials in Comparative Example 1 is out of the value range, and the mechanical properties of the prepared PA6 industrial yarn are obviously worse than those of the PA6 industrial yarn prepared in Example 1; Comparative Example 2 does not add high relative viscosity PA6B, and the mechanical properties of the prepared industrial yarn are obviously worse than those of the industrial yarn prepared in Example 4; Comparative Example 3 does not use low relative viscosity PA6A, and the mechanical properties of the prepared industrial yarn are obviously worse than those of the industrial yarn prepared in Example 3. The mechanical properties of the high-strength and low-shrinkage PA6 industrial yarn prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Table 3. Figure 4

[0041] The above examples are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the above examples, the ordinary skilled in the art can still modify or equivalently replace the specific embodiments of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application is within the protection scope of the claims of the application to be granted.​

Claims

1. A process for the production of high-strength low-shrinkage PA 6 industrial yarn, characterized in that, The method comprises the following steps: S1: stirring and premixing PA6A with a relative viscosity of 2.4-2.8 and a mass fraction of 90-99% and PA6B with a relative viscosity of 3.4-4.0 and a mass fraction of 1-10%, drying to remove water to obtain PA6 spinning particles; stirring and premixing PA6A with a low relative viscosity and PA6B with a high relative viscosity, drying to remove water to obtain PA6 spinning particles; S2: adding an antioxidant with a mass fraction of 0.1-1.0% and a temperature of 300°C or higher to the PA6 spinning particles prepared in step S1, preparing PA6 primary fibers by a melt spinning machine, coating the fibers with an antioxidant oil with a mass fraction of 3.0-5.0%, and then passing through a subsequent drafting system to prepare high-strength and low-shrinkage PA6 industrial yarn by using a multi-stage drafting technology and a high-temperature tension setting technology; the multi-stage drafting technology is a multi-coupling regulation technology of a first-stage drafting ratio, a second-stage drafting temperature, and a second-stage drafting ratio, wherein the first-stage drafting ratio is 2.5-4.5, the second-stage drafting temperature is 140-180°C, and the second-stage drafting ratio is 1.1-1.5; the high-temperature tension setting technology is a coupling regulation technology of a heat setting temperature and a heat setting tension, wherein the heat setting temperature is 200-225°C, and the difference between the setting roller speed and the tension roller speed is 1-5%.

2. A high-strength low-shrinkage PA 6 industrial yarn, characterized in that, The high-strength and low-shrinkage PA6 industrial yarn prepared by the method of claim 1 has a fineness of 80 dtex, a tensile strength of 7.05-10.32 cN / dtex, and an elongation at break of 13-30%.

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