Honeycomb-like porous chinlon functional fiber and preparation method thereof

Abstract

The invention relates to the technical field of polyamide fibers, in particular to a honeycomb-like porous chinlon functional fiber and a preparation method thereof.The method comprises the steps that firstly, chinlon and alkali-soluble polyester containing sulfonic acid groups are subjected to melt mixing and melt spinning, the spun alkali-soluble fiber is subjected to alkali dissolution treatment, a KOH solution with the concentration being 10-20% is adopted, and the polyamide functional fiber is obtained; and treating at 70-90 DEG C for 2-3 hours to obtain the honeycomb-like alkali-soluble polyamide fiber. According to the invention, the alkali-soluble polyester is creatively added and is dissolved by an alkaline dissolving agent to form a three-dimensional microporous structure layer, and a plurality of irregular holes are formed in the axial direction of the polyamide fiber; by means of the formed holes, the moisture absorption performance of the fiber is greatly improved, and the problem of contradictory balance between hydrophilic durability and mechanical properties of the fiber in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyamide fibers, in particular to a honeycomb-like porous functional fiber and a preparation method thereof. BACKGROUND

[0002] Polyamide fibers (nylon fibers) are widely used in clothing, home textiles and industrial fields due to their high strength, wear resistance and easy processability. However, the traditional nylon fibers have obvious deficiencies in terms of moisture absorption, air permeability and environmental protection.

[0003] In the preparation of moisture absorption and quick drying performance of conventional nylon fibers, the moisture absorption and air permeability are basically achieved by changing the fiber cross-sectional shape or surface coating process, but the effect is very small. For example, the moisture absorption is improved by preparing a special cross-sectional design (such as cross-shaped, trilobal, and grooved) through a physical method, but the capillary effect is weak, the moisture absorption rate is low (the initial water absorption time is > 120 seconds), and the durability is poor (the capillary effect decreases by 35-42% after 20 washes).

[0004] Even if the traditional nylon fibers can achieve the purpose of moisture absorption and sweat release to some extent by using the capillary micropores between the grooves of the fibers, it is difficult to spin ultra-fine fibers. Especially when preparing fibers that need to be stretched, the problem of floating silk and broken ends is serious, and it is difficult to form; the strength of the stretched fiber is low, and the mechanical properties are unstable, which seriously increases the production cost of enterprises and reduces the product quality.

[0005] COPET is a material that can be dissolved under alkaline conditions. In the existing blending technology, when nylon and COPET are melt-mixed, due to the difference in molecular chain polarity, the compatibility is poor, and the interfacial bonding force is weak, resulting in high spinning breakage rate, low fiber strength and other problems. At the same time, the moisture absorption and hydrophobicity of traditional fibers are difficult to balance. The market usually uses surface coating of hydrophilic agents to temporarily improve the moisture absorption and hydrophobic effect, but the coating is easy to fall off, and the performance decreases significantly after washing.

[0006] Changing the characteristics of the fiber by blending includes physical blending or simple chemical modification, which cannot achieve the durability improvement of moisture absorption and moisture transfer function through structural design. For example, adding a hydrophilic agent can improve the moisture absorption, but the mechanical properties of the fiber are sacrificed. The current alkali dissolution technology is not mature, although there are research and development of alkali-soluble fibers, but the controllable solubility is poor, and the gradient pore structure cannot be accurately formed, resulting in low moisture absorption efficiency or sudden decrease in fiber strength.

[0007] To this end, based on the current problems of the preparation of the functional fibers of the polyamide fiber, such as moisture absorption, sweat, quick drying and the like, the first, the conventional polyamide fiber improves the moisture absorption by changing the fiber cross section shape, but the effect is limited, the second, the spinning process of the ultrafine fiber has the problems of high breakage rate and low strength, the third, the polyamide and COPET have poor compatibility, resulting in unstable performance of the blended fiber, the fourth, the existing fiber is difficult to consider high moisture absorption, mechanical properties and degradability, and the physical groove design or surface coating process has poor durability and low moisture absorption rate, therefore, the polyamide fiber with persistent moisture absorption function is developed, and the mechanical strength and mechanical stability are ensured when the ultrafine fiber is prepared. SUMMARY

[0008] The purpose of the present application is to solve the problems of poor moisture absorption, low spinning stability and environmental pollution of traditional fibers, and realize the synergistic optimization of lightweight, high moisture absorption and air permeability and degradability.

[0009] Specifically, the following technical scheme is adopted in the present application: A kind of functional fiber of porous polyamide fiber of imitating honeycomb shape is prepared by the following steps: Step 1: raw material preparation, polyamide and alkali-soluble polyester containing sulfonic acid group are mixed in a proportion of 70-95:30-5;The moisture content of polyamide chip is less than 600 ppm, and the moisture content of alkali-soluble polyester is less than 60 ppm; Step 2: melt mixing, the polyamide chip and the alkali-soluble polyester are melt mixed by screw extruder, and the temperature is controlled in sections, specifically: one zone 240-255 DEG C;Two zones 250-265 DEG C;Three zones 255-267 DEG C;Four zones 260-265 DEG C;Five zones 260-265 DEG C, the box temperature is 258-262 DEG C;Screw rotation speed: 25-30 rpm, mixing time 3-5 minutes; Step 3: melt spinning, then the mixture is melt spun, the spinning temperature is 260-265 DEG C, the side blowing temperature is 17-20 DEG C, the wind speed is 0.4-0.6 m / s, the specific spinning speed is: GR1: 3500-3700 m / min, GR2: 4200-4500 m / min, GR3: 4200-4500 m / min, the hot box temperature is 150-160 DEG C, and the winding speed is 4400-4600 m / min; Step 4: the alkali-soluble fiber spun is treated with alkali, a KOH solution with a concentration of 10-20% is used at 70-90 DEG C for 2-3 hours to obtain the alkali-soluble polyamide fiber with imitating honeycomb shape.

[0010] Further, the polyamide of step 1 is PA6 or PA66.

[0011] Further, the alkali-soluble polyester of step 1 contains 5-15 mol% of isophthalic acid-5-sodium sulfonate.

[0012] Further, the nylon chip in step 1 is first pretreated, specifically, vacuum drying at 80-100℃ for 4-6 hours, so that the water content is reduced to ≤400 ppm.

[0013] Further, the alkali-soluble polyester chip in step 1 is subjected to pre-crystallization treatment, specifically: temperature 150-170℃ for 1 h, drying temperature ≤170℃, time ≥6 hours.

[0014] Further, in step 3, the side blowing temperature is 17-20℃, and the wind speed is 0.4-0.6 m / s.

[0015] A honeycomb-like porous nylon functional fiber is prepared by the above preparation method.

[0016] Further, the porosity of the fiber obtained in step 4 is ≥4-8%, and the breaking strength is ≥4.00 cN / dtex.

[0017] Further, the fiber surface obtained in step 4 has a honeycomb-like micropore with multiple pores, and the micropore has an irregular shape with a pore size of about 0.1-1 μm.

[0018] The present application blends and melts nylon (PA6 / PA66) with alkali-soluble polyester containing sulfonic acid groups (ratio 90-95:5-10), utilizes the characteristics of isophthalic acid that is easily subjected to alkaline hydrolysis in strong alkali, and finally leads to the decomposition of the material, forms differential dissolution with the alkali resistance of nylon, and thus generates a honeycomb-like porous structure. This combination has not been reported in the prior art, and breaks through the limitations of traditional single material or conventional blending system.

[0019] The segmented temperature control (up to 270℃) of the screw extruder and the spinning conditions (such as gradient spinning speed GR1-GR3, hot box temperature) are precisely designed to ensure uniform melting and blending of the two-phase material and avoid thermal degradation. The parameters of alkali reduction treatment (6-10% KOH, 70-90℃) are optimized for the mixed system, so that COPET is completely dissolved, the nylon skeleton is not damaged, and a stable porous structure is formed.

[0020] Generally, alkali reduction treatment is commonly used for pure polyester fibers (such as polyester), in order to reduce the crystallinity of polyester and improve flexibility. However, for nylon, the dyeing effect will be greatly reduced after reduction treatment, and this technical operation is usually considered as a disadvantage. This scheme reverses the situation, converts the disadvantage into a structural advantage by introducing alkali-soluble polyester as a "sacrificial phase", which has a breakthrough in technical inspiration.

[0021] Through the above scheme, the honeycomb porous structure fiber is prepared, so that the porous is used to endow the fiber with excellent moisture absorption and air permeability, and light weight characteristics.

[0022] In the polyamide melting process, the on-line multi-point adding device is used to introduce a monomer containing a sulfonic acid group for copolymerization to form an alkali-soluble polyester-polyamide copolymer containing a sulfonic acid group. The copolymer is hydrolyzed and broken under alkaline (pH>10) conditions, which destroys the continuity of the polymer chain, dissolves on the surface of the PA skeleton axis, and forms many irregular honeycomb micro-hole structures. The capillary effect of the pores accelerates the adsorption and diffusion of moisture; at the same time, the density of the PA skeleton is reduced, the moisture absorption and air permeability of the product are improved, the material density is reduced, and the light weight is realized. Overall, the alkali-soluble polyester containing a sulfonic acid group is blended with polyamide to produce alkali-soluble fibers, and then treated with alkali to prepare honeycomb alkali-soluble fibers.

[0023] The present application successfully realizes the controllable phase separation of the fiber structure by introducing an alkali-soluble polyester blending system. The sulfonic acid group (the sulfonic acid group itself has hydrophilic and hydrophobic effects, so the residual sulfonic acid group in the PA skeleton after alkali dissolution can increase the air permeability and sweat-releasing performance of the fiber) significantly improves the moisture absorption and sweat-releasing performance of the fiber. The present application provides a new way for the development of functional composite fibers.

[0024] By adjusting the spinning process parameter combination, the fiber cross section and pore distribution morphology can be precisely controlled. The fabric made of porous polyamide fiber after hydrophilic modification has a cycle service life extended by 3-5 times. The breaking strength is greater than or equal to 4.00 cN / dtex. In addition to adding graphene, other functions such as ultraviolet protection and coolness can also be added.

[0025] The conventional physical groove cross-section design or surface coating process is used for the moisture absorption and quick-drying polyamide fiber, and there are technical bottlenecks such as limited moisture absorption rate and poor durability (the capillary effect decreases by 35%-42% after 20 times of washing). The application innovatively adds alkali-soluble polyester, and after being dissolved by an alkali dissolving agent, a three-dimensional microporous structure layer is formed, and a plurality of irregular holes are formed in the axial direction of the polyamide fiber. It has been found through actual measurement that the moisture regain of the fiber is increased to 8.2-9.5% (compared with 4.5-5.6% of the traditional product), and the water evaporation speed is increased to 4.2-5.8 cm³ / min (3.1-3.9 cm³ / min of the traditional fiber), and this breakthrough improvement is due to the synergistic effect of the multi-stage capillary effect formed by the micropores and the dynamic wetting of the sulfonic acid group, effectively breaking the contradiction and balance problem between the hydrophilic durability and the mechanical properties of the fiber in the traditional technology, and the product has excellent physical properties and significant moisture absorption, and the wearing comfort is improved.

[0026] Compared with the prior art, the application has the following beneficial effects: The application innovatively adds alkali-soluble polyester, and after being dissolved by an alkali dissolving agent, a three-dimensional microporous structure layer is formed, and a plurality of irregular holes are formed in the axial direction of the polyamide fiber; the formed holes greatly improve the moisture absorption performance of the fiber, and solve the contradiction and balance problem between the hydrophilic durability and the mechanical properties of the fiber in the traditional technology; Based on the compatibility problem of the alkali-soluble polyester and the polyamide at present, the interface bonding fracture strength of the polyamide and the COPET is increased by 30% through the compatibilizer and the segmented temperature control, the fracture strength is greater than or equal to 4.00 cN / dtex, and the spinning breakage rate is reduced to less than 3%; the porosity of the fiber after alkali dissolution is greater than or equal to 8-9%, the moisture absorption rate is increased by 50%; the water evaporation speed is 4.2-5.8 cm³ / min, and the moisture regain is 8.2-9.5%; The polyamide fiber prepared by the application has the advantages of high strength, high uniformity, dyeing property, light weight, excellent moisture absorption and air permeability, and is suitable for sports clothes and medical textiles; The method of the application has degradable characteristics, specifically, after the alkali-soluble COPET is treated by alkali, hydrolysis occurs, the remaining PA skeleton is removed after the COPET is removed, the preparation process meets the environmental protection requirements, and micro-plastic pollution is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is the surface appearance diagram of the honeycomb-shaped alkali-soluble polyamide fiber obtained after alkali reduction treatment of the application.

[0028] Figure 2 It is the state diagram of the honeycomb-shaped alkali-soluble polyamide fiber obtained after alkali reduction treatment of the application before dissolution.

[0029] Figure 3is a state diagram of the imitation honeycomb-shaped alkali-soluble nylon fiber after the alkali-reduction treatment of the present application. DETAILED DESCRIPTION

[0030] Representative embodiments illustrated in the drawings will now be further specified. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. Rather, it is intended to encompass alternative forms, modifications, and equivalents that can be included within the spirit and scope of the described embodiments as defined by the claims appended hereto.

[0031] Example 1: An 80D porous nylon fiber.

[0032] PA6 raw material with water content less than 600 ppm was selected at an addition ratio of 70%, and COPET with water content less than 650 ppm was set at an addition ratio of 30%. PA6 and COPET were melt blended, with a process of twin-screw extrusion at 270-285°C, tank temperature at 262°C, screw speed at 25 rpm, mixing for 3-5 min, spinning at 265°C, side-blowing temperature at 18°C, wind speed at 0.5 m / s, winding speed at 4500 m / min, and alkali treatment (20% KOH, 80-95°C, 3h).

[0033] Results: Linear density deviation rate: 0.09%; Breaking strength: 4.20 cN / dtex; After alkali dissolution, the skeleton porosity was 4-8%.

[0034] As shown in Figure 2 and Figure 3 , are state diagrams before and after dissolution.

[0035] Example 2: A 70D porous nylon fiber.

[0036] PA6 raw material with water content less than 600 ppm was selected at an addition ratio of 75%, and COPET with water content less than 650 ppm was set at an addition ratio of 20%. PA6 and COPET were melt blended, with a process of twin-screw extrusion at 270-285°C, tank temperature at 260°C, screw speed at 27 rpm, mixing for 3-5 min, spinning at 260°C, side-blowing temperature at 19°C, wind speed at 0.5 m / s, winding speed at 4200 m / min, and alkali treatment (20% KOH, 80-95°C, 3h).

[0037] Results: Linear density deviation rate: 0.09%; Breaking strength: 4.20 cN / dtex; After alkali dissolution, the skeleton porosity is 4-8%.

[0038] Example 3: A 50D porous polyamide fiber.

[0039] PA6 raw material with water content less than 600 ppm is selected at an addition ratio of 95%, and COPET with water content less than 650 ppm is set at an addition ratio of 5%. PA6 and COPET are melt blended, and the process is as follows: double screw extrusion at 270-285°C, box temperature at 265°C, screw speed at 27 rpm, mixing for 3-5 min, spinning at 265°C, side blowing temperature at 20°C, wind speed at 0.5 m / s, winding speed at 4000 m / min, and alkali treatment (20% KOH, 80-95°C, 3h).

[0040] Results: Linear density deviation rate: 0.20%; Breaking strength: 3.60 cN / dtex; After alkali dissolution, the skeleton porosity is 4-8%.

[0041] Examples 1-3 are designed according to the scheme of the present application.

[0042] Comparative Example 1: In this comparative example, the alkali-soluble polyester contains less than 5 mol% of sodium 5-sulfoisophthalic acid.

[0043] Linear density deviation rate: 0.40%; Breaking strength: 4.50 cN / dtex; After alkali dissolution, the skeleton porosity is 0.3-0.5%.

[0044] Comparative Example 2: In this comparative example, the alkali-soluble polyester contains more than 15 mol% of sodium 5-sulfoisophthalic acid.

[0045] Linear density deviation rate: 0.55%; Breaking strength: 3.15 cN / dtex; After alkali dissolution, the skeleton porosity is 10-25%.

[0046] The products of Examples 1-3 are subjected to moisture regain testing, and the structure makes the fiber moisture regain increase to 8.2-9.5%. The moisture evaporation speed of the traditional fiber is 4.2-5.8 cm3 / min, and that of the traditional fiber is 3.1-3.9 cm3 / min. This breakthrough improvement is due to the synergistic effect of the multi-stage capillary effect of the micropore formation and the dynamic wetting of the sulfonic acid group, effectively breaking the contradiction balance between the hydrophilicity durability and the mechanical properties of the fiber in the traditional technology. The product has excellent physical properties and significant moisture absorption, and improves the wearing comfort.

[0047] The strength of the products of Examples 1-3 and Comparative Example 1 is compared, so that the influence of the content change of sodium 5-sulfonate isophtalic acid is compared.

[0048] The comparison of Examples 1-3 and Comparative Example 2 proves the data of moisture absorption, mechanical strength and durability of the scheme of the application, which proves that the scheme of the application has good moisture absorption and mechanical strength performance.

[0049] It is obvious to those skilled in the art that certain modifications, combinations and variations can be made on the basis of the above teachings.

Claims

1. A method for preparing a honeycomb-like porous nylon functional fiber, characterized in that: It is prepared by the following steps: Step 1: Raw material preparation. Mix nylon with alkali-soluble polyester containing sulfonic acid groups at a ratio of 70-95:30-5; the moisture content of the nylon chips is less than 600 ppm, and the moisture content of the alkali-soluble polyester is less than 60 ppm. Step 2: Melt mixing. The nylon chips and alkali-soluble polyester are melt-mixed using a screw extruder with segmented temperature control: Zone 1 240-255℃; Zone 2 250-265℃; Zone 3 255-267℃; Zone 4 260-265℃; Zone 5 260-265℃; chamber temperature 258-262℃; screw speed: 25-30 rpm; mixing time 3-5 minutes. Step 3: Melt spinning. The mixture is then melt-spun. The spinning temperature is 260-265℃, the side-blowing air temperature is 17-20℃, and the air velocity is 0.4-0.6 m / s. The specific spinning speeds are: GR1: 3500-3700m / min, GR2: 4200-4500m / min, GR3: 4200-4500m / min. The hot box temperature is 150-160℃, and the winding speed is 4400-4600m / min. Step 4: The alkali-soluble fibers produced by spinning are subjected to alkali dissolution treatment using a 10-20% KOH solution at 70-90℃ for 2-3 hours to obtain honeycomb-like alkali-soluble nylon fibers.

2. The method for preparing the honeycomb-like porous nylon functional fiber according to claim 1, characterized in that: The nylon used in step 1 is PA6 or PA66.

3. The method for preparing the honeycomb-like porous nylon functional fiber according to claim 1, characterized in that: The alkali-soluble polyester in step 1 contains 5-15 mol% sodium isophthalic acid-5-sulfonate.

4. The method for preparing the honeycomb-like porous nylon functional fiber according to claim 1, characterized in that: In step 1, the nylon chips are first pretreated, specifically by vacuum drying at 80-100℃ for 4-6 hours to reduce the moisture content to ≤400ppm.

5. The method for preparing the honeycomb-like porous nylon functional fiber according to claim 1, characterized in that: In step 1, the alkali-soluble polyester chips undergo a pre-crystallization treatment, specifically: maintaining the temperature at 150-170℃ for 1 hour, drying at a temperature ≤170℃ for ≥6 hours.

6. A honeycomb-like porous nylon functional fiber, characterized in that: It is prepared by the preparation method described in any one of claims 1-5.

7. The honeycomb-like porous nylon functional fiber according to claim 6, characterized in that: The fiber has a porosity of ≥60% and a breaking strength of ≥4.00 cN / dtex.

8. The honeycomb-like porous nylon functional fiber according to claim 7, characterized in that: The fiber surface has a gradient distribution of honeycomb micropores with a pore size of 0.1-1 μm.

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