A high-strength hydrogel / ultrafine fiber nonwoven composite material, a preparation method and applications thereof

Abstract

The application belongs to the technical field of hydrogel and ultrafine fiber, and provides a high-strength hydrogel / ultrafine fiber non-woven composite material, a preparation method and application thereof. The method comprises the following steps: independently melting a first polymer and a second polymer, and performing composite spinning on the obtained melt to obtain water-soluble polyvinyl alcohol bicomponent fibers, wherein the first polymer is thermoplastic polyvinyl alcohol; performing drafting, carding, reinforcing and water-soluble fiber opening treatment on the water-soluble polyvinyl alcohol bicomponent fibers to obtain a solution containing non-woven material; mixing the solution containing non-woven material and an additive solution, and sequentially performing cross-linking and freezing treatment to obtain the high-strength hydrogel / ultrafine fiber non-woven composite material. The composite material takes ultrafine fibers as a skeleton, realizes mutual coating between the hydrogel and the ultrafine fibers, has super-high mechanical strength, and has a good application prospect in the fields of masks, wound dressings, cooling patches and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydrogel and ultrafine fiber technology, and particularly relates to a high-strength hydrogel / ultrafine fiber non-woven composite material and a preparation method and application thereof. BACKGROUND

[0002] Melt-spun bicomponent ultrafine fibers have attracted much attention due to their excellent mechanical properties, fine fiber morphology and scalable preparation. Non-woven materials prepared from the fibers have good application prospects in the fields of ultrafine fiber synthetic leather, filter materials and wiping materials. However, there is little research on the application of bicomponent ultrafine fibers in the field of hydrogel. Polyvinyl alcohol bicomponent fibers can not only realize complete fiber splitting under green and low energy consumption, solve the problems of difficult splitting, easy pollution and high energy consumption of bicomponent fibers, but also have certain research value in the field of hydrogel due to the swelling property of polyvinyl alcohol.

[0003] Polyvinyl alcohol hydrogel is a cross-linked polymer network that swells in water. Due to its soft and water-containing characteristics, it has become a promising material in many fields such as biomedical engineering, flexible sensors and environmental research. However, traditional polyvinyl alcohol hydrogel is usually very fragile and easily broken due to loose cross-linking, low solid content and homogeneous structure, which greatly limits its application range.

[0004] To solve the above problems, patent CN115895155A discloses a preparation of poly-p-dioxanone / polyvinyl alcohol hydrogel, which uses poly-p-dioxanone as a reinforcing material, disperses it in a polyvinyl alcohol hydrogel as a host material, forms a hydrogel with a network interpenetrating structure, and thus improves the mechanical properties of the polyvinyl alcohol hydrogel; patent CN117736475A proposes a preparation method of a high-strength and wear-resistant hydrogel, which freezes and then thaws a polyvinyl alcohol / chitosan aqueous solution to obtain a polyvinyl alcohol / chitosan hydrogel, and then performs salt precipitation treatment, annealing treatment, and water dialysis balance on the polyvinyl alcohol / chitosan hydrogel to obtain a high-strength and wear-resistant hydrogel; patent CN116903977A invents a polyvinyl alcohol fabric hydrogel, which soaks a vinylon fabric in a sulfuric acid aqueous solution to reduce the vinylon to polyvinyl alcohol, rinses it with deionized water to obtain a polyvinyl alcohol fabric, then immerses it in a crosslinking agent, swells it sufficiently, and places it between two layers of polypropylene film, and then uses a physical freeze-thaw method to prepare a polyvinyl alcohol fabric gel. However, the polyvinyl alcohol hydrogel produced by the above preparation methods still has problems such as poor mechanical properties, complex preparation process, and the need to introduce other polymers, which cannot meet the actual application requirements. Therefore, how to prepare a polyvinyl alcohol hydrogel with excellent mechanical properties, high water content, and ultra-fine fiber skeleton has become a problem to be solved in the field of hydrogel. SUMMARY

[0005] The present application aims to overcome the problems in the prior art and provide a high-strength hydrogel / ultra-fine fiber non-woven composite material and a preparation method and application thereof.

[0006] To achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a high-strength hydrogel / ultra-fine fiber non-woven composite material, which comprises the following steps:

[0008] (1) independently melt the first polymer and the second polymer to obtain a melt of the first polymer and a melt of the second polymer; and composite spinning the melt of the first polymer and the melt of the second polymer to obtain water-soluble polyvinyl alcohol bi-component fibers; the first polymer is a thermoplastic polyvinyl alcohol;

[0009] (2) drawing the water-soluble polyvinyl alcohol bi-component fibers to obtain short fibers;

[0010] (3) carding the short fibers to obtain a polyvinyl alcohol bi-component fiber web;

[0011] (4) reinforcing the polyvinyl alcohol bi-component fiber web to obtain a water-soluble polyvinyl alcohol bi-component carding-needling non-woven material;

[0012] (5) The water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material is subjected to water-soluble fiber opening treatment to obtain a solution containing nonwoven material.

[0013] (6) The solution containing the nonwoven material and the additive solution are mixed and cross-linked and frozen in sequence to obtain the high-strength hydrogel / microfiber nonwoven composite material.

[0014] Preferably, the thermoplastic polyvinyl alcohol in step (1) has a weight-average molecular weight of 6600-7200, a degree of alcoholysis of 88-99%, a degree of polymerization of 300-700, and a melt flow index of 31-52 g / 10 min.

[0015] The second polymer includes polyester, polyamide, polybutylene adipate / terephthalate, or polylactic acid;

[0016] The mass ratio of the first polymer to the second polymer is 1–5:5–9.

[0017] Preferably, the die temperature of the composite spinning in step (1) is 230-250°C, and the composite spinning speed is 500-4000 m / min.

[0018] Preferably, the stretching method in step (2) is dry heat stretching, the stretching temperature is 95-105℃, and the stretching ratio is 3.5-5.5 times.

[0019] Preferably, the reinforcement method in step (4) is needle punching, with a needle punching density of 500–1500 needles / cm². 2 The acupuncture depth is 4–8 mm, the acupuncture frequency is 500–2000 times / min, and the acupuncture step size is 4–10 mm / needle.

[0020] Preferably, the mass fraction of the solution containing nonwoven material in step (5) is 2-15%.

[0021] Preferably, the additive in the additive solution in step (6) includes one or more of the following: sodium tetraborate, glutaraldehyde, sodium sulfate, zinc sulfate, maleic anhydride, phthaloyl chloride, phthalic anhydride, glutaric anhydride, succinic anhydride, phthalic acid, epichlorohydrin, formaldehyde, sodium hydroxide, potassium hydroxide, and boric acid; the mass fraction of the additive solution is 10-20%.

[0022] The mass fraction of the additive in the solution obtained by mixing in step (6) is 1-10%;

[0023] The crosslinking temperature in step (6) is 40–100°C, and the crosslinking time is 1–6 h.

[0024] Preferably, the freezing process in step (6) includes the following steps:

[0025] Freeze at 0 to -20°C for 2 to 8 hours. After freezing, thaw at 5 to 30°C for 1 to 5 hours. Repeat the above process 2 to 5 times to complete the freezing treatment.

[0026] The present invention also provides a method for preparing the high-strength hydrogel / microfiber nonwoven composite material, thereby obtaining the high-strength hydrogel / microfiber nonwoven composite material.

[0027] The present invention also provides the application of the high-strength hydrogel / microfiber nonwoven composite material in the fields of wound dressings, face masks or cooling patches.

[0028] The beneficial effects of this invention are:

[0029] (1) This invention uses thermoplastic polyvinyl alcohol as one of the raw materials to achieve water-soluble fiber opening of bicomponent fibers. It is not only green and environmentally friendly, fast and convenient, but also can achieve complete fiber opening. It solves the problems of high energy consumption, easy environmental pollution and difficulty in fiber opening of common orange petal and island bicomponent fibers. In addition, the diversity of other raw material selection and the diversity of fiber cross-section structure provide a wider range of application value for water-soluble polyvinyl alcohol bicomponent carding-needling nonwoven materials.

[0030] (2) The present invention uses a specific drawing process, which provides a good performance basis for subsequent processes. The specific combing and reinforcement processes are selected so that the prepared material has the characteristics of good isotropy, excellent mechanical properties and dense structure.

[0031] (3) Based on the form of polyvinyl alcohol component in the prepared high-strength hydrogel / microfiber nonwoven composite material, the high-strength hydrogel / microfiber nonwoven composite material prepared by the present invention uses microfiber as the skeleton to achieve mutual encapsulation between hydrogel and microfiber, and has ultra-high mechanical strength. It has good application prospects in the fields of face masks, wound dressings, and cooling patches. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the conjugated bicomponent melt spinning machine of the present invention. Figure 1 In the diagram, 2-1 is feed port A, 2-2 is screw A, 2-3 is feed port B, 2-4 is screw B, 2-5 is metering pump, 2-6 is orange petal type or island type spinning assembly, 2-7 is fiber bundle, and 2-8 is winding device.

[0033] Figure 2 This is a schematic diagram of the constant temperature drawing chamber in this invention. Figure 2In the diagram, 3-1 is drawing roller 1, 3-2 is drawing roller 2, 3-3 is drawing roller 3, 3-4 is drawing roller 4, 3-5 is constant temperature drawing box, and 3-6 is heating wire;

[0034] Figure 3 This is a schematic diagram of the preparation process of the high-strength hydrogel / microfiber nonwoven composite material in this invention;

[0035] Figure 4 This is a schematic diagram of the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material and the high-strength hydrogel / microfiber nonwoven composite material of the present invention. Figure 4 In the diagram, 4-1 is a water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material, 4-2 is the fiber cross-sectional structure of the water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material, 4-3 is a high-strength hydrogel / microfiber nonwoven composite material, and 4-4 is the fiber cross-sectional structure of the high-strength hydrogel / microfiber nonwoven composite material.

[0036] Figure 5 The image shows the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material in Example 1 under an electron microscope at 300x magnification.

[0037] Figure 6 The image shows the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material in Example 1 under an electron microscope at 500x magnification.

[0038] Figure 7 This is an electron microscope image of the high-strength hydrogel / microfiber nonwoven composite material in Example 1 at 500x magnification.

[0039] Figure 8 This is an electron microscope image of the high-strength hydrogel / microfiber nonwoven composite material in Example 1 at 255x magnification;

[0040] Figure 9 This is a diagram showing the diameter distribution of the ultrafine fibers in the high-strength hydrogel / ultrafine fiber nonwoven composite material in Example 1. Detailed Implementation

[0041] This invention provides a method for preparing a high-strength hydrogel / microfiber nonwoven composite material, comprising the following steps:

[0042] (1) The first polymer and the second polymer are melted independently to obtain a melt of the first polymer and a melt of the second polymer; the melt of the first polymer and the melt of the second polymer are combined and spun to obtain a water-soluble polyvinyl alcohol bicomponent fiber; the first polymer is thermoplastic polyvinyl alcohol.

[0043] (2) The water-soluble polyvinyl alcohol bicomponent fiber is stretched to obtain short fiber;

[0044] (3) The short fibers are combed to obtain a polyvinyl alcohol bicomponent fiber web;

[0045] (4) The polyvinyl alcohol bicomponent fiber web is reinforced to obtain a water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material.

[0046] (5) The water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material is subjected to water-soluble fiber opening treatment to obtain a solution containing nonwoven material.

[0047] (6) The solution containing the nonwoven material and the additive solution are mixed and cross-linked and frozen in sequence to obtain the high-strength hydrogel / microfiber nonwoven composite material.

[0048] In this invention, the weight-average molecular weight of the thermoplastic polyvinyl alcohol in step (1) is preferably 6600-7200, more preferably 6700-7100, and even more preferably 6800-7000; the degree of hydrolysis of the thermoplastic polyvinyl alcohol is preferably 88-99%, more preferably 90-98%, and even more preferably 92-95%; the degree of polymerization of the thermoplastic polyvinyl alcohol is preferably 300-700, more preferably 400-600, and even more preferably 500; the melt flow index of the thermoplastic polyvinyl alcohol is preferably 31-52 g / 10 min, more preferably 35-45 g / 10 min, and even more preferably 40-42 g / 10 min.

[0049] In this invention, the thermoplastic polyvinyl alcohol in step (1) is prepared according to patent CN116876153A.

[0050] In this invention, the second polymer preferably includes polyester, polyamide, polybutylene adipate / terephthalate, or polylactic acid.

[0051] In this invention, the mass ratio of the first polymer to the second polymer is preferably 1 to 5: 5 to 9, more preferably 2 to 4: 6 to 8, and even more preferably 3: 7.

[0052] In this invention, in step (1), melting and spinning are preferably carried out in a conjugate bicomponent melt spinning machine. A schematic diagram of a conjugate bicomponent melt spinning machine is shown below. Figure 1As shown; the first polymer and the second polymer are added to feed port A 2-1 and feed port B 2-3 respectively, and extruded through screw A 2-2 and screw B 2-4 respectively. Then, they are metered by metering pump 2-5, and then composite spun through orange petal type or island type spinning assembly 2-6. The spun fibers are bundled to obtain fiber bundle 2-7, and finally wound on the yarn bobbin through winding device 2-8 to form water-soluble polyvinyl alcohol bicomponent fiber; the cross-sectional structure of the water-soluble polyvinyl alcohol bicomponent fiber preferably includes island type, orange petal type, orange petal-indeterminate island type or island-indeterminate island type.

[0053] In this invention, the temperature of screw A is preferably set as follows: Zone 1 190-210℃, Zone 2 200-220℃, Zone 3 210-220℃, Zone 4 210-230℃, Zone 5 220-240℃; more preferably, it is set as follows: Zone 1 195-205℃, Zone 2 205-215℃, Zone 3 212-218℃, Zone 4 215-225℃, Zone 5 225-235℃; and even more preferably, it is set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 215℃, Zone 4 220℃, Zone 5 230℃. 0℃; The preferred temperature setting for screw B is: Zone 1 170~190℃, Zone 2 190~210℃, Zone 3 210~230℃, Zone 4 215~235℃, Zone 5 230~240℃, further preferably: Zone 1 175~185℃, Zone 2 195~205℃, Zone 3 215~225℃, Zone 4 220~230℃, Zone 5 232~238℃, and even more preferably: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 225℃, Zone 5 235℃.

[0054] In this invention, the die temperature of the composite spinning in step (1) is preferably 230-250°C, more preferably 235-245°C, and even more preferably 240°C; the composite spinning speed is preferably 500-4000 m / min, more preferably 1000-3500 m / min, and even more preferably 2000-3000 m / min; the cooling air temperature of the composite spinning is preferably 10-20°C, more preferably 12-18°C, and even more preferably 15°C.

[0055] In this invention, in step (2), the water-soluble polyvinyl alcohol bicomponent fiber wound on the filament bobbin is unwound and then drawn; the drawing is preferably carried out in a constant temperature drawing chamber, and a schematic diagram of the constant temperature drawing chamber is shown below. Figure 2 As shown; the temperature inside the entire constant temperature drawing box 3-5 is kept constant by electric heating, and the heating wire is 3-6, so that the fiber is heated evenly. The constant temperature drawing box has a multi-stage drawing structure with 4 drawing rollers 3-1, 3-2, 3-3, and 3-4, and 3 drawing zones.

[0056] In this invention, the stretching method in step (2) is preferably dry heat stretching, which can avoid the dissolution of polyvinyl alcohol components; the stretching temperature is preferably 95-105℃, more preferably 97-103℃, and even more preferably 100-101℃; the stretching ratio (the ratio of the speed of stretching roller 3-4 to the speed of stretching roller 3-1) is preferably 3.5-5.5 times, more preferably 4-5 times, and even more preferably 4.5 times. The specific stretching ratio achieves sufficient stretching of the water-soluble polyvinyl alcohol bicomponent fiber; the mechanical properties of the water-soluble polyvinyl alcohol bicomponent fiber are further improved through stretching.

[0057] In this invention, after the stretching in step (2), the obtained sample is cut with a fiber cutter to obtain short fibers; the length of the short fibers is preferably 20-60 mm, more preferably 30-50 mm, and even more preferably 40-45 mm.

[0058] In this invention, step (3) carding is preferably carried out in a high-speed random carding machine, and the carding method is preferably high-speed random carding. The short fibers are fully randomized through the triangular vortex zone between the cylinder and the randomizing roller, thereby achieving the isotropy of the polyvinyl alcohol bicomponent fiber web.

[0059] In this invention, the reinforcement method described in step (4) is preferably acupuncture, which is preferably performed in an active elliptical trajectory high-speed acupuncture machine, and the acupuncture density is preferably 500-1500 needles / cm. 2 A further preferred value is 800–1200 thorns / cm. 2 More preferably, 900–1000 spines / cm 2 The depth of acupuncture is preferably 4-8 mm, more preferably 5-7 mm, and even more preferably 6 mm; the frequency of acupuncture is preferably 500-2000 times / min, more preferably 1000-1500 times / min, and even more preferably 1200-1300 times / min; the step size of acupuncture is preferably 4-10 mm / needle, more preferably 5-9 mm / needle, and even more preferably 6-8 mm / needle.

[0060] In this invention, the water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material obtained in step (4) can be used in the fields of filter materials, microfiber synthetic leather, or wiping materials. The areal density of the water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material is 300-900 g / m³. 2The longitudinal tensile breaking strength is 880–1100 N (test standard GB / T 24218.3-2010), the longitudinal tensile breaking elongation is 22–40% (test standard GB / T 24218.3-2010), the transverse tensile breaking strength is 850–1076 N (test standard GB / T 24218.3-2010), the transverse tensile breaking elongation is 30–50% (test standard GB / T 24218.3-2010), and the air permeability is 205–281 L / m³. 2 / s (test standard is GB / T24218.15-2018), softness performance score is 71~82 (test standard is AATCC TM202), and water-soluble fiber opening rate is 100%.

[0061] In this invention, the mass fraction of polyvinyl alcohol in the solution containing nonwoven material in step (5) is preferably 2-15%, more preferably 6-12%, and even more preferably 7-10%.

[0062] In this invention, in step (5), the water-soluble polyvinyl alcohol bicomponent carded-needle nonwoven material is placed in a mold containing water (the water-soluble polyvinyl alcohol bicomponent carded-needle nonwoven material and the mold are the same size, which can avoid the collapse of the nonwoven material structure after polyvinyl alcohol dissolves in water, and also facilitates the uniform dispersion of polyvinyl alcohol components in the nonwoven material structure) for water-soluble fiber opening treatment. After the polyvinyl alcohol components are dissolved, the water-soluble fiber opening treatment is completed, and a solution containing nonwoven material is obtained.

[0063] In this invention, the temperature of the water-soluble fiber-opening treatment is determined according to the degree of hydrolysis of thermoplastic polyvinyl alcohol. When the degree of hydrolysis of thermoplastic polyvinyl alcohol is 88-90%, the temperature of the water-soluble fiber-opening treatment needs to be ≥60℃. When the degree of hydrolysis of thermoplastic polyvinyl alcohol is 90-95% but not including 90%, the temperature of the water-soluble fiber-opening treatment needs to be ≥80℃. When the degree of hydrolysis of thermoplastic polyvinyl alcohol is 95-99% but not including 95%, the temperature of the water-soluble fiber-opening treatment needs to be ≥90℃.

[0064] In this invention, the additive in the additive solution in step (6) preferably includes one or more of sodium tetraborate, glutaraldehyde, sodium sulfate, zinc sulfate, maleic anhydride, phthaloyl chloride, phthalic anhydride, glutaric anhydride, succinic anhydride, phthalic acid, epichlorohydrin, formaldehyde, sodium hydroxide, potassium hydroxide, and boric acid; the mass fraction of the additive solution is preferably 10-20%, more preferably 12-18%, and even more preferably 15-16%.

[0065] In this invention, the mass fraction of the additive in the solution obtained by mixing in step (6) is preferably 1 to 10%, more preferably 3 to 8%, and even more preferably 5 to 6%.

[0066] In this invention, the crosslinking temperature in step (6) is preferably 40-100°C, more preferably 50-90°C, and even more preferably 70-80°C; the crosslinking time is preferably 1-6 hours, more preferably 2-5 hours, and even more preferably 3-4 hours.

[0067] In this invention, after the crosslinking in step (6) is completed, the mold is placed in an ultrasonic instrument for ultrasonication to remove air bubbles in the system. Finally, a freezing treatment is performed. After the freezing treatment, the solution is in the form of a hydrogel, which is a high-strength hydrogel / microfiber nonwoven composite material. The ultrasonic temperature is preferably 50-100℃, more preferably 60-90℃, and more preferably 70-80℃. The ultrasonic time is preferably 1-6h, more preferably 2-5h, and more preferably 3-4h.

[0068] In this invention, the freezing process in step (6) preferably includes the following steps:

[0069] Freeze at 0 to -20°C for 2 to 8 hours. After freezing, thaw at 5 to 30°C for 1 to 5 hours. Repeat the above process 2 to 5 times to complete the freezing treatment.

[0070] In this invention, the freezing process in step (6) preferably further includes the following steps:

[0071] Freeze at -5 to -15°C for 3 to 7 hours. After freezing, thaw at 10 to 25°C for 2 to 4 hours. Repeat the above process 3 to 4 times to complete the freezing treatment.

[0072] In this invention, the freezing process in step (6) more preferably includes the following steps:

[0073] Freeze at -10 to -12°C for 4 to 6 hours. After freezing, thaw at 15 to 20°C for 3 to 3.5 hours. Repeat the above process 3 times to complete the freezing treatment.

[0074] A schematic diagram of the preparation process of the high-strength hydrogel / microfiber nonwoven composite material in this invention is shown below. Figure 3 As shown.

[0075] A schematic diagram of the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material and the high-strength hydrogel / microfiber nonwoven composite material in this invention is shown below. Figure 4 As shown; Figure 4 In the diagram, 4-1 represents a water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material, 4-2 represents the fiber cross-sectional structure of the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material, 4-3 represents a high-strength hydrogel / microfiber nonwoven composite material, and 4-4 represents the fiber cross-sectional structure of the high-strength hydrogel / microfiber nonwoven composite material. Figure 4As can be seen from the figure, the fiber cross-sectional structure of the water-soluble polyvinyl alcohol bicomponent carded-needle nonwoven material can be island type, orange petal type, orange petal-island type or island-island type, etc. (as shown in 4-3). After it is prepared into a high-strength hydrogel / ultrafine fiber nonwoven composite material, the polyvinyl alcohol component in the fiber is dissolved, and the fiber cross-sectional structure after dissolution is shown in 4-4.

[0076] The present invention also provides a method for preparing the high-strength hydrogel / microfiber nonwoven composite material, which yields a high-strength hydrogel / microfiber nonwoven composite material with a tensile breaking strength of 12-14 MPa and a water absorption ratio of 450-1020%.

[0077] The present invention also provides the application of the high-strength hydrogel / microfiber nonwoven composite material in the fields of wound dressings, face masks or cooling patches.

[0078] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0079] Example 1

[0080] Thermoplastic polyvinyl alcohol (weight average molecular weight 7000, degree of alcoholysis 98%, degree of polymerization 500, melt flow index 40 g / 10 min) and polylactic acid were added to feed port A2-1 (thermoplastic polyvinyl alcohol) and feed port B2-3 (polylactic acid), respectively, and fed through screws A2-2 and B2-3, respectively. 2-4 Extrusion, then metering by metering pump 2-5, followed by composite spinning via orange-petal-shaped spinning assembly 2-6. The spun fibers are bundled to obtain fiber bundles 2-7, and finally wound onto a yarn bobbin via winding device 2-8 to form water-soluble polyvinyl alcohol bicomponent fibers with an orange-petal-shaped cross-sectional structure. The mass ratio of thermoplastic polyvinyl alcohol to polylactic acid is 3:7. During the spinning process, the temperature of screw A is set as follows: Zone 1 200℃, Zone 2 210℃, Zone 3 215℃, Zone 4 220℃, Zone 5 230℃; the temperature of screw B is set as follows: Zone 1 180℃, Zone 2 200℃, Zone 3 220℃, Zone 4 225℃, Zone 5 235℃; the spinning die temperature is 230℃, the speed is 1000m / min, and the cooling air temperature is 15℃.

[0081] The water-soluble polyvinyl alcohol bicomponent fibers wound on the yarn bobbin are unwound and then subjected to dry heat drawing in a constant temperature drawing chamber. The temperature of the entire constant temperature drawing chamber 3-5 is kept constant by electric heating. The heating wire is 3-6. The drawing temperature is set to 100℃. The constant temperature drawing chamber has a multi-stage drawing structure with 4 drawing rollers 3-1, 3-2, 3-3, and 3-4, and 3 drawing zones. The drawing ratio is set to 3.5 times. After drawing, the fibers are cut into 30mm short fibers using a fiber cutter.

[0082] Short fibers are carded using a high-speed random carding machine to obtain a polyvinyl alcohol bicomponent fiber web, which is then reinforced (needling) using an active elliptical trajectory high-speed needle punching machine. The process parameters for the active elliptical trajectory high-speed needle punching machine are set as follows: needle density is 1500 needles / cm². 2 The depth is 8mm, the frequency is 1000 times / min, and the step size is 8mm / needle; a water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material is obtained through reinforcement.

[0083] A water-soluble polyvinyl alcohol (PVA) bicomponent carded-needle-punched nonwoven material was placed in a mold containing water (the size of the water-soluble PVA bicomponent carded-needle-punched nonwoven material was the same as that of the mold) and subjected to water-soluble fiber opening treatment at a temperature of 90°C. After the PVA component dissolved, the water-soluble fiber opening treatment was completed, resulting in a solution containing the nonwoven material (the mass fraction of PVA in the solution containing the nonwoven material was 6%). Then, a sodium hydroxide solution with a mass fraction of 15% was added and mixed, resulting in a sodium hydroxide mass fraction of 5% in the mixed solution. Crosslinking was carried out at 70°C for 4 hours. After crosslinking, the mold was placed in an ultrasonic instrument and ultrasonicated at 80°C for 2 hours. It was then frozen at -5°C for 6 hours. After freezing, it was thawed at 20°C for 2 hours. The above process was repeated 5 times to obtain a high-strength hydrogel / microfiber nonwoven composite material.

[0084] In this embodiment, the electron microscope image of the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material at 300x magnification is shown below. Figure 5 As shown; This embodiment features a 500x electron microscope image of the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material. Figure 6 As shown; the electron microscope image of the high-strength hydrogel / microfiber nonwoven composite material in this embodiment at 500x magnification, as shown. Figure 7 As shown; the electron microscope image of the high-strength hydrogel / microfiber nonwoven composite material in this embodiment at 255x magnification, as shown. Figure 8 As shown. From Figures 5 to 8It can be seen that the average diameter of the composite fibers in the water-soluble polyvinyl alcohol bicomponent carded-needle nonwoven material is 25μm, and the fiber distribution is relatively loose. In the high-strength hydrogel / microfiber nonwoven composite material prepared by water-soluble fiber opening and cross-linking, the microfiber and hydrogel are evenly distributed, and the hydrogel fills the three-dimensional structure of the microfiber nonwoven material.

[0085] The microstructure of the ultrafine fibers in the prepared high-strength hydrogel / ultrafine fiber nonwoven composite material was photographed using a desktop scanning electron microscope, and the diameter of the ultrafine fibers was measured using particle size distribution software. This yielded a diameter distribution map of the ultrafine fibers in the high-strength hydrogel / ultrafine fiber nonwoven composite material of this embodiment. Figure 9 As shown. From Figure 9 It can be seen that the equivalent diameter of the ultrafine fibers in the high-strength hydrogel / ultrafine fiber nonwoven composite material in this embodiment is 4.1 μm.

[0086] Example 2

[0087] Keeping other conditions unchanged in Example 1, the degree of hydrolysis of thermoplastic polyvinyl alcohol was modified to 88%, and the process of "placing water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material in a mold containing water for water-soluble fiber opening treatment" and subsequent processes were not performed, thus obtaining water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material.

[0088] Example 3

[0089] Keeping other conditions unchanged in Example 1, the mass ratio of thermoplastic polyvinyl alcohol and polylactic acid was modified to 5:5, and the process of "placing the water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material in a mold containing water for water-soluble fiber opening treatment" and subsequent processes were omitted, resulting in water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material.

[0090] Example 4

[0091] Keeping other conditions unchanged in Example 1, the draw ratio was modified to 4.5 times, and the process of "placing the water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material in a mold containing water for water-soluble fiber opening treatment" and subsequent processes were not performed, thus obtaining the water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material.

[0092] Example 5

[0093] Keeping other conditions unchanged in Example 1, the draw ratio was modified to 5.5 times, the mass ratio of thermoplastic polyvinyl alcohol and polylactic acid was 8:2, and the process of "placing water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material in a mold containing water for water-soluble fiber opening treatment" and subsequent processes were not performed, thus obtaining water-soluble polyvinyl alcohol bicomponent carding-needle-punched nonwoven material.

[0094] Example 6

[0095] By keeping other conditions unchanged in Example 1, the mass fraction of polyvinyl alcohol in the solution containing nonwoven material was modified to 9%, resulting in a high-strength hydrogel / microfiber nonwoven composite material.

[0096] Example 7

[0097] By keeping other conditions unchanged in Example 1, the mass fraction of polyvinyl alcohol in the solution containing nonwoven material was modified to 12%, resulting in a high-strength hydrogel / microfiber nonwoven composite material.

[0098] Example 8

[0099] By keeping other conditions unchanged in Example 1, the degree of alcoholysis of thermoplastic polyvinyl alcohol was modified to 88%, and the temperature of water-soluble fiber opening treatment was modified to 60°C, resulting in a high-strength hydrogel / microfiber nonwoven composite material.

[0100] The properties of the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven materials in Examples 1-5 were tested, and the test results are shown in Table 1. Specifically, the test methods are as follows:

[0101] (1) Determination of tensile fracture properties

[0102] The tensile breaking properties of nonwoven materials were determined using an electronic universal testing machine (CZ-4000D1, Yangzhou Changzhe Testing Machinery Co., Ltd., China). According to standard GB / T 24218.3-2010, water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material was cut into rectangles with a length of 200 mm and a width of 50 mm. The clamping distance of the instrument was 100 mm, the tensile speed was 100 mm / min, and 5 tests were performed. The average value was calculated.

[0103] (2) Determination of air permeability

[0104] The air permeability was tested using a fully automatic air permeability measuring instrument (YG461E-III, Ningbo Textile Instrument Factory, China). The test was conducted according to the standard GB / T 24218.15-2018 Textiles - Nonwovens - Test Methods - Part 15: Determination of Air Permeability. The air permeability instrument was set to fully automatic mode, and the unit was L / m. 2 / s, place the water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven material under the holder of the air permeability meter, measure the sample of each process 5 times, and then calculate the average value.

[0105] (3) Softness test

[0106] The softness performance was tested using the PhabrOmeter (F1S3-10, USA) according to the standard AATCC TM202 "Evaluation of Relative Hand Feel Values ​​of Textiles and Apparel: Instrumental Method". The sampling area was 100 cm². 2 Samples are taken using a disc sampler, and a 100g weight is added to the instrument. The softness of the sample is measured based on the softness score displayed on the instrument (scores range from 1 to 100, with 100 being the best). Samples from each process are measured three times, and the average value is taken.

[0107] Table 1. Performance test results of water-soluble polyvinyl alcohol two-component carded-needle-punched nonwoven materials in Examples 1-5.

[0108] Case Example 1 Example 2 Example 3 Example 4 Example 5 Area density (g / m 2 )]]> 600 500 550 700 700 Softness score 71 74 72 78 82 Machine direction tensile strength (N) 916 894 880 1023 1100 Machine direction elongation at break (%) 32 34 40 28 22 Cross direction tensile strength (N) 942 882 860 984 1076 Cross direction elongation at break (%) 47 45 50 41 31 Air permeability (L / m 2 / s) 205 231 255 274 281

[0109] The properties of the high-strength hydrogel / microfiber nonwoven composite materials obtained in Examples 1 and 6-8 were tested, and the performance test results of the high-strength hydrogel / microfiber nonwoven composite materials in Examples 1 and 6-8 are shown in Table 2. Specifically, the test methods are as follows:

[0110] (1) Determination of tensile fracture properties

[0111] The mechanical properties of high-strength hydrogel / microfiber nonwoven composites were characterized by measuring their tensile strength. Samples were cut into dumbbell shapes and stretched at a steady strain rate of 1 mm / min until fracture. Each experiment was repeated three times, and the average value was taken.

[0112] (2) Water absorption performance test

[0113] Different 15mm × 15mm test samples were immersed in distilled water at 20–30℃ for the same amount of time, then removed and weighed after removing excess solution from the nylon bag. The water absorption ratio at saturation can be calculated using the following formula:

[0114]

[0115] In the formula, W s W represents the mass of the swollen hydrogel at time t. d The dry weight of the sample was used. Three parallel experiments were repeated, and the water absorption ratio was taken as the average of the three experiments.

[0116] Table 2. Performance test results of high-strength hydrogel / microfiber nonwoven composite materials in Examples 1 and 6-8.

[0117]

[0118]

[0119] The test results above show that the water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material prepared by this invention has a longitudinal tensile breaking strength of 880–1100 N (test standard GB / T24218.3-2010), a longitudinal tensile breaking elongation of 22–40% (test standard GB / T24218.3-2010), a transverse tensile breaking strength of 850–1076 N (test standard GB / T24218.3-2010), a transverse tensile breaking elongation of 30–50% (test standard GB / T24218.3-2010), and an air permeability of 205–281 L / m³. 2 / s (test standard is GB / T 24218.15-2018), softness performance score is 71-82 (test standard is AATCC TM202), water-soluble fiber opening rate is 100%; the tensile breaking strength of high-strength hydrogel / microfiber nonwoven composite material is 9-14MPa, and the water absorption ratio can reach 450-1020%.

[0120] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength hydrogel / microfiber nonwoven composite material, characterized in that, Includes the following steps: (1) The first polymer and the second polymer are melted independently to obtain a melt of the first polymer and a melt of the second polymer; the melt of the first polymer and the melt of the second polymer are combined and spun to obtain water-soluble polyvinyl alcohol bicomponent fiber; The first polymer is thermoplastic polyvinyl alcohol; (2) The water-soluble polyvinyl alcohol bicomponent fiber is stretched to obtain short fibers; (3) The short fibers are combed to obtain a polyvinyl alcohol bicomponent fiber web; (4) The polyvinyl alcohol bicomponent fiber web is reinforced to obtain a water-soluble polyvinyl alcohol bicomponent carded-needle punched nonwoven material. (5) Water-soluble polyvinyl alcohol bicomponent carded-needle-punched nonwoven material is subjected to water-soluble fiber opening treatment to obtain a solution containing nonwoven material; (6) Mix the solution containing the nonwoven material and the additive solution, and perform cross-linking and freezing treatment in sequence to obtain the high-strength hydrogel / microfiber nonwoven composite material; The thermoplastic polyvinyl alcohol in step (1) has a weight-average molecular weight of 6600~7200, a degree of alcoholysis of 88~99%, a degree of polymerization of 300~700, and a melt flow index of 31~52 g / 10 min. The mass ratio of the first polymer to the second polymer is 1~5:5~9; The stretching method described in step (2) is dry heat stretching, the stretching temperature is 95~105℃, and the stretching ratio is 3.5~5.5 times; The reinforcement method described in step (4) is needle acupuncture, with a needle density of 500~1500 needles / cm². 2 The acupuncture depth is 4~8mm, the acupuncture frequency is 500~2000 times / min, and the acupuncture step is 4~10mm / needle; When the degree of hydrolysis of thermoplastic polyvinyl alcohol is 88~90%, the temperature of water-soluble fiber splitting treatment is ≥60℃; when the degree of hydrolysis of thermoplastic polyvinyl alcohol is 90~95% but not including 90%, the temperature of water-soluble fiber splitting treatment is ≥80℃; when the degree of hydrolysis of thermoplastic polyvinyl alcohol is 95~99% but not including 95%, the temperature of water-soluble fiber splitting treatment is ≥90℃.

2. The preparation method of the high-strength hydrogel / microfiber nonwoven composite material as described in claim 1, characterized in that, The second polymer includes polyester, polyamide, polybutylene terephthalate, or polylactic acid.

3. The method for preparing the high-strength hydrogel / microfiber nonwoven composite material as described in claim 1 or 2, characterized in that, In step (1), the die temperature of the composite spinning process is 230~250℃, and the composite spinning speed is 500~4000m / min.

4. The preparation method of the high-strength hydrogel / microfiber nonwoven composite material as described in claim 3, characterized in that, The mass fraction of polyvinyl alcohol in the solution containing nonwoven material in step (5) is 2-15%.

5. The method for preparing the high-strength hydrogel / microfiber nonwoven composite material as described in claim 4, characterized in that, The additives in the additive solution described in step (6) include one or more of the following: sodium tetraborate, glutaraldehyde, sodium sulfate, zinc sulfate, maleic anhydride, phthaloyl chloride, phthalic anhydride, glutaric anhydride, succinic anhydride, phthalic acid, epichlorohydrin, formaldehyde, sodium hydroxide, potassium hydroxide, and boric acid; the mass fraction of the additive solution is 10-20%. The mass fraction of the additive in the solution obtained by mixing in step (6) is 1-10%; The cross-linking temperature in step (6) is 40~100℃, and the cross-linking time is 1~6h.

6. The method for preparing the high-strength hydrogel / microfiber nonwoven composite material as described in claim 5, characterized in that, The freezing process in step (6) includes the following steps: Freeze at 0~-20℃ for 2~8 hours. After freezing, thaw at 5~30℃ for 1~5 hours. Repeat the above process 2~5 times to complete the freezing treatment.

7. The high-strength hydrogel / microfiber nonwoven composite material prepared by the preparation method of any one of claims 1 to 6.

8. The application of the high-strength hydrogel / microfiber nonwoven composite material according to claim 7 in the fields of wound dressings, face masks or cooling patches.

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