A fast photo-crosslinkable anti-swelling high-strength polyvinyl alcohol hydrogel and a preparation method thereof

Abstract

The present application relates to the technical field of high molecular hydrogel materials, and particularly relates to a fast photo-crosslinkable anti-swelling high-strength polyvinyl alcohol hydrogel and a preparation method thereof. The present application firstly performs alkyl modification on polyvinyl alcohol to enhance the hydrophobic bonding between polyvinyl alcohol chains and reduce the swelling rate of the hydrogel; then further introduces a photosensitive group to enable the polyvinyl alcohol to have fast photo-crosslinking capability; then forms a primary hydrogel with nanocrystalline crosslinking under the conditions of freezing and solvent phase transition; then forms a stable chemical crosslinking network through ultraviolet light irradiation; finally, the hydrogel is stretched and heat set in the stretched state to improve the polymer chain orientation degree and crystallization degree, so that a polyvinyl alcohol hydrogel material with high strength, low swelling, fast photo-curing and excellent biocompatibility is obtained. The obtained hydrogel can be widely applied in the fields of flexible electronics, biosensing, neural electrodes, tissue engineering and implantable medical devices.

Description

Technical Field

[0001] This invention relates to the field of synthetic materials technology, and in particular to a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel and its preparation method. Background Technology

[0002] Hydrogels are a class of soft materials composed of three-dimensional polymer networks capable of absorbing large amounts of water. Due to their high water content, good flexibility, and mechanical properties similar to biological tissues, they show broad application prospects in tissue engineering, drug delivery, flexible electronics, biosensing, and implantable medical devices. To meet the performance requirements of different applications, researchers have developed various hydrogel systems with different chemical compositions, network structures, and functional properties in recent years. Among them, polyvinyl alcohol (PVA) has become one of the most representative materials in the field of biomedical hydrogels due to its excellent hydrophilicity, low coefficient of friction, low protein adsorption, good biocompatibility, and ease of processing.

[0003] However, traditional polyvinyl alcohol (PVA) hydrogels typically suffer from insufficient mechanical properties, poor fatigue resistance, and a tendency to swell in aqueous environments, thus limiting their further application in flexible implant devices, bioelectronic interfaces, and long-term biomaterials. Particularly in applications such as neural electrodes, flexible sensors, and tissue engineering scaffolds, materials not only need good biocompatibility but also must simultaneously meet requirements for high mechanical strength, low swelling, long-term structural stability, and rapid prototyping. Therefore, developing PVA hydrogels that combine high strength, low swelling, and rapid prototyping capabilities is of great significance.

[0004] Currently, the construction of polyvinyl alcohol (PVA) hydrogels mainly relies on physical or chemical crosslinking. Chemical crosslinking typically involves introducing chemical crosslinking agents (such as glutaraldehyde, boric acid, genipin, etc.) into the PVA system to promote the formation of a stable three-dimensional network structure of PVA molecular chains. Although this method can effectively improve the mechanical properties of hydrogels, its preparation process is often complex, crosslinking agent residues are difficult to completely remove, and may lead to a decrease in the biocompatibility of the material. For example, Chinese patent CN202010363171.6 discloses a high-strength PVA hydrogel with multiple chemical crosslinking processes and its preparation method. Although this method can obtain high-strength hydrogels, its preparation process is complex due to the involvement of multiple chemical crosslinking processes, and potential crosslinking agent residues limit its application in the biomedical field.

[0005] In contrast, physical crosslinking methods are more conducive to maintaining the biocompatibility of polyvinyl alcohol hydrogels because they do not require the introduction of highly toxic crosslinking agents. Common physical crosslinking methods include repeated freeze-thaw cycles, salting-out, and solvent phase transitions. These methods mainly construct a three-dimensional network structure by inducing the formation of microcrystalline regions and hydrogen bonding within the polyvinyl alcohol segments. For example, Chinese patent CN202510079727.1 discloses a polyvinyl alcohol hydrogel patch with a double-disc structure, its preparation method, and its applications. The hydrogel prepared by this method exhibits good biocompatibility, but its preparation cycle is long, the process is relatively cumbersome, and the resulting hydrogel still suffers from limited mechanical strength and high swelling ratio, making it difficult to meet the actual needs of high-performance biomedical materials.

[0006] In recent years, photocrosslinking technology has attracted widespread attention in the field of hydrogel materials due to its advantages such as fast reaction speed, strong spatiotemporal controllability, mild processing conditions, and ease of in-situ molding. By introducing photosensitive groups such as methacryloyl, acryloyl, or norbornene groups into the polymer side chains, materials can rapidly form chemical crosslinked networks under ultraviolet or visible light irradiation. However, existing photocrosslinked polyvinyl alcohol (PVA) systems typically suffer from problems such as a single crosslinked network, insufficient mechanical properties, and high swelling ratios. Furthermore, the network structure formed by simple photocrosslinking lacks effective orientation enhancement and microcrystalline strengthening mechanisms, making it difficult to simultaneously achieve high strength and flexibility. Moreover, most existing PVA photocrosslinking systems rely solely on a single chemical crosslinked network, lacking synergistic control over the hydrophobic association of polymer chains, nanocrystalline structure, and oriented crystallization structure. Therefore, it is difficult to simultaneously achieve key properties such as rapid ultraviolet curing, high mechanical strength, low swelling performance, good flexibility, and long-term structural stability.

[0007] Therefore, there is an urgent need to develop a novel polyvinyl alcohol hydrogel system. By modifying polyvinyl alcohol with hydrophobic alkylation and photosensitive groups, and combining it with multi-level structure regulation strategies such as freeze-induced phase transition-induced microcrystalline physical crosslinking, ultraviolet photochemical crosslinking, and stretching-heat-setting orientation enhancement, a polyvinyl alcohol hydrogel material with high strength, low swelling, rapid photocrosslinking, and excellent biocompatibility can be constructed to meet the application requirements of high-performance hydrogels in the fields of flexible bioelectronic devices and implantable medical materials.

[0008] To address this, a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel and its preparation method are proposed. Summary of the Invention

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel, characterized in that it is obtained by coagulation molding, ultraviolet light crosslinking, and post-treatment of a photocrosslinkable polyvinyl alcohol composition; the photocrosslinkable polyvinyl alcohol composition includes the following components: alkylated and photosensitive group-modified polyvinyl alcohol, a photoinitiator, and a solvent; the alkylated and photosensitive group-modified polyvinyl alcohol is obtained by sequentially modifying polyvinyl alcohol with alkyl aldehydes and photosensitive molecules.

[0010] As a preferred embodiment of the present invention, the photoinitiator includes one of Irgacure 2959, Irgacure 1173, riboflavin RF, eosin EY (tetrabromofluorescein), lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), and sodium phenyl-2,4,6-trimethylbenzoylphosphonate (NAP), and the solvent includes one or more of water, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0011] As a preferred embodiment of the present invention, the alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 6,000 to 200,000 and a degree of alcoholysis of 60% to 100%. The concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 1% to 90%. The amount of photoinitiator is 0.1% to 5% of the mass of the alkylated and photosensitive group-modified polyvinyl alcohol.

[0012] As a preferred embodiment of the present invention, the alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 80,000 to 170,000 and a degree of alcoholysis of 70% to 99%. The concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 10% to 60%. The amount of photoinitiator is 0.5% to 2% of the mass of the alkylated and photosensitive group-modified polyvinyl alcohol.

[0013] As a preferred embodiment of the present invention, the alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 120,000 to 150,000 and a degree of alcoholysis of 90% to 97%. The concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 20% to 40%. The photoinitiator is Irgacure 2959, and its dosage is 0.8% to 1.5% of the mass of the alkylated and photosensitive group-modified polyvinyl alcohol.

[0014] A method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel includes the following steps: S1, Preparation of alkylated polyvinyl alcohol: a polyvinyl alcohol solution is prepared by dissolving in a good solvent and mechanically stirring until completely dissolved. Then, an acidic reagent solution is added to adjust the pH of the reaction solution. An alkyl aldehyde solution is added dropwise and mechanically stirred until the reaction is complete. The reaction solution is then washed in a poor solvent and redissolved in a good solvent under mechanical stirring. An alkaline reagent solution is added to adjust the pH of the reaction solution. The reaction solution is then washed again in a poor solvent and dried to obtain solid alkylated polyvinyl alcohol. S2. Preparation of alkylated and photosensitive group modified polyvinyl alcohol: Dissolve the above solid alkylated polyvinyl alcohol in a good solvent to prepare a solution, stir mechanically until completely dissolved, add photosensitive molecule solution dropwise, stir mechanically until the reaction is complete, pour the reaction solution into a poor solvent for washing, and dry to obtain solid alkylated and photosensitive group modified polyvinyl alcohol; S3. Preparation of hydrogel: The modified polyvinyl alcohol, photoinitiator and good solvent are added into a stirred tank in proportion, heated and mechanically stirred until completely dissolved, filtered under pressure, and the filtrate is squeezed into a degassing tank and degassed under vacuum to obtain a homogeneous solution. The homogeneous solution is poured into a rectangular mold and placed in a coagulation bath to solidify and form. Then, it is rapidly photocrosslinked by ultraviolet light irradiation. Finally, after stretching, heat setting and washing, a high-strength polyvinyl alcohol hydrogel with anti-swelling properties that can be rapidly photocrosslinked is obtained.

[0015] As a preferred embodiment of the present invention, the good solvent includes one or more of water, DMF, DMAc, NMP, and DMSO; the poor solvent includes one or more of n-hexane, cyclohexane, petroleum ether, toluene, dichloromethane, chloroform, ethyl acetate, diethyl ether, acetone, ethanol, and ethylene glycol; the acidic reagent includes one or more of hydrochloric acid, sulfuric acid, acetic acid, and trifluoroacetic acid; the basic reagent includes one or more of sodium hydroxide, triethylamine, and sodium carbonate; the alkyl aldehyde includes one or more of butyraldehyde, hexanal, octaldehyde, dodecaldehyde, hexadecaldehyde, and octadecaldehyde; the photosensitive molecule includes one or more of methacrylic anhydride, methacryloyl chloride, acryloyl chloride, acrylic anhydride, glycidyl methacrylate, 5-norbornene-2-carboxylic acid, allyl glycidyl ether, and cinnamoyl chloride; and the coagulation bath components include one or more of ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

[0016] As a preferred embodiment of the present invention, in the preparation of S1 and alkylated polyvinyl alcohol, the dissolution temperature of polyvinyl alcohol is 20-250°C, and the concentration of the prepared polyvinyl alcohol solution is 0.5%-80%; the concentration of the acidic reagent solution is 1%-60%, and the pH of the reaction solution is adjusted to 0.1-7; the molar ratio of the alkyl aldehyde solution to the side chain hydroxyl group of polyvinyl alcohol is 0.0001-1, and the concentration is 1%-70%; the unsuitable solvent is 0.5-50 times the volume of the reaction solution; the concentration of the alkaline reagent solution is 1%-60%, and the pH of the reaction solution is adjusted to 1-13; the drying is performed by freeze-drying under vacuum, high-temperature vacuum drying, or high-temperature drying.

[0017] As a preferred embodiment of the present invention, in the preparation of S2, alkylated and photosensitive group modified polyvinyl alcohol, the concentration of the solution prepared by dissolving the alkylated polyvinyl alcohol in a good solvent is 0.5% to 80%; the molar ratio of the photosensitive molecule solution to the side chain hydroxyl group of the alkylated polyvinyl alcohol is 0.0001 to 1, and the concentration is 1% to 70%.

[0018] As a preferred technical solution of the present invention, in the preparation of S3 and the hydrogel, the temperature of the filtrate extruded into the degassing kettle is set to 0-200℃, the vacuum degassing time is 1h-72h; the temperature of the coagulation bath is -60-70℃, the ultraviolet light is configured with a wavelength of 200-400nm, an intensity of 20-150W, and an ultraviolet light irradiation time of 5s-180s; the stretching is 0.1-50 times, the heat setting temperature is 20-300℃, and the water washing temperature is 10-100℃.

[0019] As a preferred embodiment of the present invention, the polyvinyl alcohol is dissolved at a temperature of 40–150°C, and the concentration of the prepared polyvinyl alcohol solution is 1%–40%; the concentration of the acidic reagent solution is 5%–40%, and the pH of the reaction solution is adjusted to 0.5–5; the molar ratio of the alkyl aldehyde solution to the side chain hydroxyl group of the polyvinyl alcohol is 0.001–0.5, and the concentration is 5%–40%; the unsuitable solvent is 1–40 times the volume of the reaction solution; the concentration of the alkaline reagent solution is 5%–40%, and the pH of the reaction solution is adjusted to 3–11; the alkylated polyvinyl alcohol is dissolved in a good solvent for preparation. The solution concentration is 0.5%–80%; the molar ratio of photosensitive molecular solution to alkylated polyvinyl alcohol side chain hydroxyl groups is 0.001–0.5, and the concentration is 5%–40%; the temperature of the filtrate extruded into the degassing kettle is set to 40–150℃, and the vacuum degassing time is 6h–24h; the temperature of the coagulation bath is -40–20℃, the ultraviolet light is configured with a wavelength of 365nm, an intensity of 50–100W, and an ultraviolet light irradiation time of 10s–120s; the stretching is 1–30 times, the heat setting temperature is 80–200℃, and the water washing temperature is 50–90℃.

[0020] As a preferred embodiment of the present invention, the polyvinyl alcohol has a dissolution temperature of 80–100°C, and the concentration of the prepared polyvinyl alcohol solution is 5%–15%; the acidic reagent is hydrochloric acid or trifluoroacetic acid, the concentration of the acidic reagent solution is 10%–30%, and the pH of the reaction solution is adjusted to 1–3; the alkyl aldehyde is dodecaldehyde, the molar ratio of the alkyl aldehyde solution to the side chain hydroxyl group of polyvinyl alcohol is 0.005–0.05, and the concentration is 10%–20%; the unsuitable solvent is ethanol or acetone, and the unsuitable solvent is 2–10 times the volume of the reaction solution; the alkaline reagent is triethylamine or sodium hydroxide, the concentration of the alkaline reagent solution is 10%–30%, and the pH of the reaction solution is adjusted to 6–8; The solvent concentration for dissolving alkylated polyvinyl alcohol is 0.5%–80%; the photosensitive molecule is methacrylic anhydride, and the molar ratio of the photosensitive molecule solution to the hydroxyl groups on the side chain of alkylated polyvinyl alcohol is 0.01–0.1, with a concentration of 10%–30%; the temperature of the filtrate extruded into the degassing kettle is set at 60–90℃, and the vacuum degassing time is 3h–10h; the coagulation bath component is ethylene glycol monomethyl ether, the coagulation bath temperature is -30 to -10℃, the ultraviolet light is configured with a wavelength of 365nm, an intensity of 80W, and an ultraviolet light irradiation time of 30s–90s; the stretching is 5–10 times, the heat setting temperature is 140–180℃, and the water washing temperature is 80–95℃.

[0021] Compared with the prior art, the beneficial effects that this invention can achieve are: 1. This invention enhances the hydrophobic association between polyvinyl alcohol chains through alkylation modification, and combines freeze-induced and phase-transition-induced physical crosslinking with photo-induced chemical crosslinking to form a composite crosslinking network. Compared with traditional polyvinyl alcohol hydrogels that rely solely on single physical crosslinking (such as repeated freeze-thaw cycles) or single chemical crosslinking, the hydrogel of this invention exhibits significant improvements in tensile strength, elongation at break, and fatigue resistance, meeting the high mechanical performance requirements of applications such as flexible electronics, neural electrodes, and tissue engineering scaffolds.

[0022] 2. Traditional polyvinyl alcohol (PVA) hydrogels are prone to significant swelling in aqueous environments, leading to decreased mechanical properties and dimensional distortion, severely limiting their application in implantable medical devices and long-term biomaterials. This invention, through alkylation hydrophobic modification of PVA, effectively reduces the hydrophilicity of the polymer chains and increases inter-chain hydrophobic association, thereby inhibiting water molecule penetration into the network. Simultaneously, combining high-density chemical crosslinking, nanocrystalline physical crosslinking, and a drawn oriented crystalline structure further restricts the degrees of freedom of network chain movement, significantly reducing the equilibrium swelling rate of the hydrogel. Compared to unmodified or photocrosslinked PVA hydrogels, the hydrogel of this invention exhibits extremely low volume expansion and excellent dimensional stability in physiological environments or aqueous solutions.

[0023] 3. Existing methods for preparing polyvinyl alcohol hydrogels are often time-consuming, such as repeated freeze-thaw cycles which typically take hours or even days, and are difficult to achieve in-situ molding of complex shapes. This invention introduces photosensitive groups (such as methacryl and acryloyl groups) into the side chains of polyvinyl alcohol, and combined with ultraviolet light irradiation, can rapidly form a stable chemical crosslinking network within seconds to tens of seconds. This photocrosslinking process has excellent spatiotemporal controllability, and can achieve patterning, multilayer structures, or in-situ molding through mask or optical path design, significantly shortening the preparation cycle and improving production efficiency. Compared with traditional chemical crosslinking methods involving crosslinking agents (such as glutaraldehyde and genipin), this invention avoids the problem of toxic crosslinking agent residues, simplifies the process, and is more suitable for rapid prototyping and the preparation of personalized medical devices. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0025] To make the technical means, creative features, achieved objectives, and effects of this invention easier to understand, the invention is further described below with reference to specific embodiments. However, the following embodiments are merely preferred embodiments of this invention and not all of them. Other embodiments or implementations obtained by those skilled in the art based on the embodiments or implementations described in the specific embodiments without creative effort are all within the protection scope of this invention.

[0026] Implementation Method 1: A rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel is obtained by coagulation molding, ultraviolet light crosslinking, and post-treatment of a photocrosslinkable polyvinyl alcohol composition. The photocrosslinkable polyvinyl alcohol composition includes the following components: alkylated and photosensitive group-modified polyvinyl alcohol, photoinitiator, and solvent.

[0027] Among them, alkylated and photosensitive group modified polyvinyl alcohol is obtained by successively modifying polyvinyl alcohol with alkyl aldehyde and photosensitive molecules.

[0028] The alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 6,000 to 200,000 and a degree of alcoholysis of 60% to 100%. The concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 1% to 90%. The photoinitiator includes Irgacure 2959, Irgacure 1173, riboflavin RF, eosin EY (tetrabromofluorescein), lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), sodium phenyl-2,4,6-trimethylbenzoylphosphonate (NAP), etc., and is used in an amount of 0.1% to 5% of the mass of the alkylated and photosensitive group-modified polyvinyl alcohol. The solvent includes one or more of water, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0029] The preparation method of the hydrogel includes the following steps: S1. Preparation of alkylated polyvinyl alcohol: S1-1, Alkyl chain modification: At a certain temperature (20-250℃), dissolve and prepare a 0.5%-80% polyvinyl alcohol solution with a good solvent, and mechanically stir until completely dissolved. Then, add an acidic reagent solution with a concentration of 1%-60% to adjust the pH of the reaction solution to 0.1-7. Add dropwise an alkyl aldehyde solution (concentration 1%-70%) with a molar ratio of 0.0001-1 to the hydroxyl group of the polyvinyl alcohol side chain, and mechanically stir until the reaction is complete.

[0030] S1-2, Neutralizing Acidity: Pour the reaction solution into 0.5 to 50 times its volume of a poor solvent to wash it, then redissolve it with a good solvent under mechanical stirring, add a 1% to 60% alkaline reagent solution, and adjust the pH of the reaction solution to 1 to 13.

[0031] S1-3, Cleaning and Drying: The reaction solution is washed again in a poor solvent and then dried (freezing vacuum drying, high temperature vacuum drying, or high temperature drying) to obtain solid alkylated polyvinyl alcohol.

[0032] S2. Preparation of alkylated and photosensitive group-modified polyvinyl alcohol: S2-1, Photosensitive group modification: Dissolve the above alkylated polyvinyl alcohol in a good solvent to prepare a solution with a concentration of 0.5% to 80%, stir mechanically until completely dissolved, add dropwise a photosensitive molecule solution (concentration 1% to 70%) with a molar ratio of 0.0001 to 1 to the side chain hydroxyl group of alkylated polyvinyl alcohol, and stir mechanically until the reaction is complete.

[0033] S2-2, Cleaning and Drying: Pour the reaction solution into a poor solvent for washing, and dry to obtain solid alkylated and photosensitive group modified polyvinyl alcohol.

[0034] S3. Preparation of hydrogel: S3-1. Add the modified polyvinyl alcohol, photoinitiator and good solvent to a stirred tank in proportion, heat and mechanically stir until completely dissolved, and then pressurize and filter.

[0035] S3-2. The filtrate is squeezed into a degassing kettle and degassed under vacuum at 20-200℃ for 1-72 hours to obtain a homogeneous colloid.

[0036] S3-3. Pour the homogeneous adhesive into a rectangular mold and place it in a coagulation bath at -60 to 70°C to solidify and shape it. Then, irradiate it with ultraviolet light (wavelength 200 to 400 nm, intensity 20 to 150 W) for 5 to 180 seconds to perform rapid photocrosslinking. Finally, after stretching by 0.1 to 50 times, heat setting at 20 to 300°C, and washing with water at 10 to 100°C, a high-strength polyvinyl alcohol hydrogel with anti-swelling properties that can be rapidly photocrosslinked is obtained.

[0037] The good solvents include one or more of water, DMF, DMAc, NMP, and DMSO; the bad solvents include n-hexane, cyclohexane, petroleum ether, toluene, dichloromethane, chloroform, ethyl acetate, diethyl ether, acetone, ethanol, and ethylene glycol; the acidic reagents include hydrochloric acid, sulfuric acid, acetic acid, and trifluoroacetic acid; the basic reagents include sodium hydroxide, triethylamine, and sodium carbonate; the alkyl aldehydes include butyraldehyde, hexanal, octanal, dodecaldehyde, hexadecaldehyde, and octadecaldehyde; the photosensitive molecules include methacrylic anhydride, methacryloyl chloride, acryloyl chloride, acrylic anhydride, glycidyl methacrylate, 5-norbornene-2-carboxylic acid, allyl glycidyl ether, and cinnamoyl chloride; the coagulation bath components include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

[0038] Implementation Method Two: Based on Implementation Method One, further specifying that the alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 80,000–170,000 and a degree of alcoholysis of 70%–99%; the concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 10%–60%; the amount of photoinitiator is 0.5%–2% of the mass of the alkylated and photosensitive group-modified polyvinyl alcohol; the dissolution temperature is 40–150°C; the polyvinyl alcohol concentration is 1%–40%; the acid reagent concentration is 5%–40%; the pH is 0.5–5; the alkyl aldehyde molar ratio is 0.001–0.5, and the concentration is 5%–40%; the undesirable solvent volume ratio is 1–40; the alkaline reagent concentration is 5%–40%; and the pH is… 3~11; Molar ratio of photosensitive molecules 0.001~0.5, concentration 5%~40%; Degassing temperature 40~150℃, time 6h~24h; Coagulation bath temperature -40~20℃; Ultraviolet light wavelength 365nm, intensity 50~100W, irradiation time 10s~120s; Stretch ratio 1~30 times; Heat setting temperature 80~200℃; Water washing temperature 50~90℃.

[0039] By further narrowing the range of the above parameters, the molecular weight, degree of alcoholysis, and solution concentration of polyvinyl alcohol are made more suitable for subsequent alkylation modification and photosensitive group modification. This also allows for a more stable coordination relationship between acidic conditions, alkyl aldehyde dosage, photosensitive molecule dosage, degassing conditions, coagulation bath conditions, and ultraviolet irradiation conditions. This is beneficial for improving the uniformity of the modified polyvinyl alcohol solution, shortening the time required for ultraviolet crosslinking, and improving the anti-swelling properties and mechanical strength of the hydrogel after molding.

[0040] Implementation Method 3: Based on Implementation Method 2, further specifying that the alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 120,000–150,000, a degree of alcoholysis of 90%–97%, and a concentration of alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition of 20%–40%; the photoinitiator is Irgacure 2959, used in an amount of 0.8%–1.5% of the mass of the alkylated and photosensitive group-modified polyvinyl alcohol; the dissolution temperature is 80–100°C; the polyvinyl alcohol concentration is 5%–15%; the concentration of the acidic reagent (hydrochloric acid or trifluoroacetic acid) is 10%–30%, and the pH is 1–3; the molar ratio of alkyl aldehyde (dodecanal) is 0.005–0.05, and the concentration is 10%–20%; the volume ratio of the poor solvent (ethanol or acetone) is 2–10; the concentration of the alkaline reagent (triethylamine or sodium hydroxide) is 10%–30%, and the pH is [not specified in the original text]. 6-8; Molar ratio of photosensitive molecule (methacrylic anhydride) 0.01-0.1, concentration 10%-30%; Degassing temperature 60-90℃, time 3h-10h; Coagulation bath (ethylene glycol monomethyl ether) temperature -30--10℃; Ultraviolet light 365nm, 80W, irradiation 30s-90s; Stretch ratio 5-10 times; Heat setting temperature 140-180℃; Water washing temperature 80-95℃.

[0041] By combining the above parameters, the molecular weight, degree of hydrolysis, and concentration of polyvinyl alcohol are limited to a more concentrated range, and the specific types of photoinitiators, acidic reagents, alkyl aldehydes, basic reagents, photosensitive molecules, and coagulation baths are further limited, making the alkylation modification, photosensitive group modification, coagulation molding, and ultraviolet crosslinking processes easier to control. At the same time, combined with stretching, heat setting, and water washing treatments, it is beneficial to obtain polyvinyl alcohol hydrogels that can complete crosslinking within a shorter ultraviolet irradiation time and have both anti-swelling properties and high strength.

[0042] Specific Examples: The following examples all adopt the basic scope of Embodiment 3, and adjust one or a few parameters accordingly to demonstrate the adjustability and effects of the present invention. In all examples, the photoinitiator is Irgacure 2959 (1% dosage), the alkylating agent is dodecyl aldehyde (unless otherwise specified), the photosensitive molecule is methacrylic anhydride (substitution rate and alkyl substitution rate are independently controlled), the coagulation bath is -20℃ ethylene glycol monomethyl ether (unless otherwise specified), the ultraviolet irradiation is 365nm, 80W, 60s, the draw ratio is 5 times, the heat setting is 150℃, and the water washing is 90℃. The performance data are representative values ​​from actual tests.

[0043] Example 1: Alkylated PVA concentration: 5% (solvent water), alkyl substitution rate 1%, photosensitive substitution rate 2%.

[0044] Performance: Tensile strength 18.3 MPa, elongation at break 240%, swelling rate (PBS, 37℃, 24h) 22%, cell viability 94%.

[0045] Example 2: Alkylated PVA concentration: 10%.

[0046] Performance: Tensile strength 25.6 MPa, elongation at break 220%, swelling rate 18%, cell viability 95%.

[0047] Example 3: Alkylated PVA concentration: 20%.

[0048] Performance: Tensile strength 38.2 MPa, elongation at break 190%, swelling rate 14%, cell viability 95%.

[0049] Example 4: Alkylated PVA concentration: 30%.

[0050] Performance: Tensile strength 52.7 MPa, elongation at break 170%, swelling rate 11%, cell viability 94%.

[0051] Example 5: Alkylated PVA concentration: 40%.

[0052] Performance: Tensile strength 68.4 MPa, elongation at break 150%, swelling rate 9%, cell viability 93%.

[0053] Example 6: Alkyl chain type: butyraldehyde (substitution rate 1%), concentration 40%.

[0054] Properties: Tensile strength 42.1 MPa, swelling rate 15%.

[0055] Example 7: Alkyl chain type: hexanal, concentration 40%.

[0056] Properties: Tensile strength 55.3 MPa, swelling rate 12%.

[0057] Example 8: Alkyl chain type: Octaldehyde, concentration 40%.

[0058] Properties: Tensile strength 63.8 MPa, swelling rate 10%.

[0059] Example 9: Alkyl chain type: hexadecaldehyde, concentration 40%.

[0060] Properties: Tensile strength 59.2 MPa, swelling rate 7%.

[0061] Example 10: Alkyl chain type: octadecaldehyde, concentration 40%.

[0062] Properties: Tensile strength 48.5 MPa, swelling rate 6%.

[0063] Example 11: Alkyl substitution rate: 0.1% (dodecanoic acid), concentration 40%.

[0064] Properties: Tensile strength 30.5 MPa, swelling rate 20%.

[0065] Example 12: Alkyl substitution rate: 0.3%, concentration 40%.

[0066] Properties: Tensile strength 42.3 MPa, swelling rate 16%.

[0067] Example 13: Alkyl substitution rate: 0.5%, concentration: 40%.

[0068] Properties: Tensile strength 55.6 MPa, swelling rate 12%.

[0069] Example 14: Alkyl substitution rate: 0.8%, concentration: 40%.

[0070] Properties: Tensile strength 64.2 MPa, swelling rate 10%.

[0071] Example 15: Alkyl substitution rate: 1.5%, concentration 40%.

[0072] Performance: Tensile strength 58.7 MPa, swelling rate 8% (solubility slightly decreased).

[0073] Example 16: Photosensitive substitution rate: 0.5% (methacrylic anhydride), alkyl substitution rate 1%, concentration 40%.

[0074] Properties: Tensile strength 45.2 MPa, swelling rate 14%, incomplete cross-linking under ultraviolet light.

[0075] Example 17: Photosensitive substitution rate: 1.0%, concentration 40%.

[0076] Properties: Tensile strength 62.8 MPa, swelling rate 10%.

[0077] Example 18: Photosensitive substitution rate: 3.0%, concentration 40%.

[0078] Properties: Tensile strength 70.1 MPa, swelling rate 8%.

[0079] Example 19: Photosensitive substitution rate: 5.0%, concentration 40%.

[0080] Performance: Tensile strength 72.5 MPa, swelling rate 7% (high substitution increases cost).

[0081] Example 20: Coagulation bath temperature: 0°C (ethylene glycol monomethyl ether).

[0082] Properties: Tensile strength 48.6 MPa, swelling rate 16%.

[0083] Example 21: Coagulation bath temperature: -10℃.

[0084] Properties: Tensile strength 60.3 MPa, swelling rate 11%.

[0085] Example 22: Coagulation bath temperature: -30℃.

[0086] Properties: Tensile strength 70.8 MPa, swelling rate 8%.

[0087] Example 23: Ultraviolet light irradiation time: 10s.

[0088] Properties: Tensile strength 55.2 MPa, swelling rate 13% (insufficient cross-linking).

[0089] Example 24: Ultraviolet light irradiation time: 120s.

[0090] Properties: Tensile strength 72.5 MPa, swelling rate 7%.

[0091] Example 25: Draw ratio: 10 times.

[0092] Properties: Tensile strength 85.3 MPa, swelling rate 5%, elongation at break 110%.

[0093] The following comparative examples are used to compare the effects of existing technologies or those lacking key steps.

[0094] Comparative Example 1: No alkylation modification (only photosensitive modification, substitution rate 2%), concentration 40%, the rest is the same as Example 5.

[0095] Performance: Tensile strength 12.5 MPa, swelling rate 45%, cell viability 92%.

[0096] Comparative Example 2: No photosensitive group modification (only alkylation, substitution rate 1%), no ultraviolet light irradiation, relying solely on freeze-drying phase change + stretching.

[0097] Performance: Tensile strength 15.3 MPa, swelling rate 52%, cannot be rapidly molded.

[0098] Comparative Example 3: No freezing phase change (coagulation bath) steps: direct UV crosslinking + stretching.

[0099] Properties: Tensile strength 8.7 MPa, swelling rate 68%.

[0100] Comparative Example 4: No stretching or heat setting: only alkylation, photocrosslinking, and freeze-phase change.

[0101] Properties: Tensile strength 14.2 MPa, swelling rate 35%.

[0102] Comparative Example 5: Unmodified PVA (non-alkylated, non-photosensitive), repeated freeze-thaw method (-20℃ / room temperature, 3 cycles).

[0103] Properties: Tensile strength 1.8 MPa, swelling rate 130%.

[0104] Comparative Example 6: The alkylation substitution rate was too high (dodecyl molar ratio 1.2), resulting in insolubility.

[0105] Performance: Unable to form a uniform gel.

[0106] Comparative Example 7: The photosensitive substitution rate was too low (0.01%), and the crosslinking was extremely weak after ultraviolet light irradiation.

[0107] Properties: Tensile strength 5.2 MPa, swelling rate 70%.

[0108] Comparative Example 8: The coagulation bath temperature was too high (40℃), resulting in insufficient crystal formation.

[0109] Properties: Tensile strength 7.6 MPa, swelling rate 60%.

[0110] Comparative Example 9: No UV light irradiation (skipping the photocrosslinking step).

[0111] Properties: Tensile strength 16.5 MPa, swelling rate 48% (by physical cross-linking only).

[0112] Comparative Example 10: Glutaraldehyde chemical crosslinking was used instead of photocrosslinking (no alkylation, no photosensitization), with a glutaraldehyde concentration of 1%.

[0113] Performance: Tensile strength 8.2 MPa, swelling rate 42%, cell viability 68%.

[0114] Comparative Example 11: Boric acid crosslinking (no alkylation, no photosensitization), boric acid concentration 2%.

[0115] Performance: Tensile strength 5.5 MPa, swelling rate 55%, cell viability 72%.

[0116] Comparative Example 12: Alkylation only + photocrosslinking, no stretching, no heat setting (but retains freeze-thaw phase change).

[0117] Properties: Tensile strength 22.3 MPa, swelling rate 25%.

[0118] Comparative Example 13: Alkylation only + stretching and heat setting, no photocrosslinking, no freeze-thaw phase change (direct dissolution followed by stretching).

[0119] Properties: Tensile strength 9.8 MPa, swelling rate 40%.

[0120] Comparative Example 14: Maleic anhydride modification was used instead of alkylation modification (maleic anhydride substitution rate of 5%), while photosensitive modification (2%) was retained.

[0121] Performance: Tensile strength 28.5 MPa, swelling rate 32%, cell viability 80%.

[0122] Comparative Example 15: The coagulation bath used pure water (0°C) and had no solvent phase transition capability.

[0123] Properties: Tensile strength 6.3 MPa, swelling rate 85%.

[0124] Table 1. Composition and coagulation method of the adhesive solution in each preparation example and comparative example.

[0125] Table 2 Performance Comparison of Examples and Comparative Examples

[0126] As can be seen from the above embodiments and comparative examples: This invention employs a multi-level synergistic strategy involving alkylation hydrophobic modification, introduction of photosensitive groups, cryogenic phase change-induced microcrystals, rapid crosslinking under ultraviolet light, and stretching-heat-setting orientation enhancement. The resulting hydrogel exhibits a tensile strength of up to 85 MPa and a swelling rate as low as 5%, while maintaining good cell compatibility (>90%).

[0127] The comparative examples show that the absence of any key step (alkylation, photocrosslinking, freeze-thaw phase change, stretching) leads to a significant decrease in mechanical properties or a substantial increase in swelling rate.

[0128] Compared with traditional chemical crosslinking (glutaraldehyde, boric acid) or physical crosslinking (repeated freeze-thaw cycles), this invention has significant advantages in terms of strength, swelling resistance, biocompatibility and rapid prototyping.

[0129] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel, characterized in that, It is obtained by solidification molding, ultraviolet crosslinking and post-treatment of a photocrosslinkable polyvinyl alcohol composition; The photocrosslinked polyvinyl alcohol composition comprises the following components: alkylated and photosensitive group modified polyvinyl alcohol, photoinitiator, and solvent; The alkylated and photosensitive group-modified polyvinyl alcohol is obtained by sequentially modifying polyvinyl alcohol with alkyl aldehydes and photosensitive molecules.

2. The rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 1, characterized in that, The photoinitiator includes one of Irgacure 2959, Irgacure 1173, riboflavin RF, eosin EY (tetrabromofluorescein), lithium phenyl-2,4,6-trimethylbenzoylphosphonate (LAP), and sodium phenyl-2,4,6-trimethylbenzoylphosphonate (NAP).

3. The rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 2, characterized in that, The solvent includes one or more of water, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

4. The rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 3, characterized in that, The alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 6,000 to 200,000, a degree of alcoholysis of 60% to 100%, and a concentration of alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition of 1% to 90%. The amount of photoinitiator used is 0.1% to 5% of the mass of alkylated and photosensitive group-modified polyvinyl alcohol.

5. The rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 4, characterized in that, The alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 80,000 to 170,000 and a degree of alcoholysis of 70% to 99%. The concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 10% to 60%. The amount of photoinitiator used is 0.5% to 2% of the mass of alkylated and photosensitive group-modified polyvinyl alcohol.

6. The rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 5, characterized in that, The alkylated and photosensitive group-modified polyvinyl alcohol has a molecular weight of 120,000 to 150,000 and a degree of alcoholysis of 90% to 97%. The concentration of the alkylated and photosensitive group-modified polyvinyl alcohol in the photocrosslinkable polyvinyl alcohol composition is 20% to 40%. The photoinitiator is Irgacure 2959, and the amount used is 0.8% to 1.5% of the mass of alkylated and photosensitive group-modified polyvinyl alcohol.

7. A method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel, characterized in that, Includes the following steps: S1. Preparation of alkylated polyvinyl alcohol: Prepare a polyvinyl alcohol solution by dissolving it in a good solvent and stirring mechanically until completely dissolved. Then, add an acidic reagent solution to adjust the pH of the reaction solution. Add an alkyl aldehyde solution dropwise and stir mechanically until the reaction is complete. Pour the reaction solution into a poor solvent to wash it. Then, redissolve it in a good solvent under mechanical stirring. Add an alkaline reagent solution to adjust the pH of the reaction solution. Pour the reaction solution into a poor solvent again to wash it. After drying, obtain solid alkylated polyvinyl alcohol. S2. Preparation of alkylated and photosensitive group modified polyvinyl alcohol: Dissolve the above solid alkylated polyvinyl alcohol in a good solvent to prepare a solution, stir mechanically until completely dissolved, add photosensitive molecule solution dropwise, stir mechanically until the reaction is complete, pour the reaction solution into a poor solvent for washing, and dry to obtain solid alkylated and photosensitive group modified polyvinyl alcohol; S3. Preparation of hydrogel: The modified polyvinyl alcohol, photoinitiator and good solvent are added into a stirred tank in proportion, heated and mechanically stirred until completely dissolved, filtered under pressure, and the filtrate is squeezed into a degassing tank and degassed under vacuum to obtain a homogeneous solution. The homogeneous solution is poured into a rectangular mold and placed in a coagulation bath to solidify and form. Then, it is rapidly photocrosslinked by ultraviolet light irradiation. Finally, after stretching, heat setting and washing, a high-strength polyvinyl alcohol hydrogel with anti-swelling properties that can be rapidly photocrosslinked is obtained.

8. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 7, characterized in that, The good solvent includes one or more of water, DMF, DMAc, NMP, and DMSO; The undesirable solvents include one or more of n-hexane, cyclohexane, petroleum ether, toluene, dichloromethane, chloroform, ethyl acetate, diethyl ether, acetone, ethanol, and ethylene glycol.

9. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 8, characterized in that, The acidic reagent includes one or more of hydrochloric acid, sulfuric acid, acetic acid, and trifluoroacetic acid; The alkaline reagent includes one or more of sodium hydroxide, triethylamine, and sodium carbonate.

10. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 9, characterized in that, The alkyl aldehydes include one or more of butyraldehyde, hexanal, octaldehyde, dodecaldehyde, hexadecaldehyde, and octadecaldehyde; The photosensitive molecules include one or more of methacrylic anhydride, methacryloyl chloride, acryloyl chloride, acrylic anhydride, glycidyl methacrylate, 5-norbornene-2-carboxylic acid, allyl glycidyl ether, and cinnamoyl chloride.

11. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 10, characterized in that, The coagulation bath components include one or more of ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and propylene glycol monomethyl ether.

12. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 11, characterized in that, In the preparation of S1 and alkylated polyvinyl alcohol, the dissolution temperature of polyvinyl alcohol is 20-250°C, and the concentration of the prepared polyvinyl alcohol solution is 0.5%-80%. The concentration of the acidic reagent solution is 1% to 60%, and the pH of the reaction solution is adjusted to 0.1 to 7. The molar ratio of the alkyl aldehyde solution to the polyvinyl alcohol side chain hydroxyl group is 0.0001–1, and the concentration is 1%–70%. The unsuitable solvent is 0.5 to 50 times the volume of the reaction liquid; The concentration of the alkaline reagent solution is 1% to 60%, and the pH of the reaction solution is adjusted to 1 to 13. The drying process includes freeze-drying, high-temperature vacuum drying, or high-temperature drying.

13. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 12, characterized in that, In the preparation of S2, alkylated and photosensitive group modified polyvinyl alcohol, the concentration of the solution prepared by dissolving the alkylated polyvinyl alcohol in a good solvent is 0.5% to 80%. The photosensitive molecular solution has a molar ratio of 0.0001 to 1 to the hydroxyl side chain of alkylated polyvinyl alcohol, and a concentration of 1% to 70%.

14. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 13, characterized in that, In the preparation of S3 and hydrogel, the temperature of the filtrate squeezed into the degassing kettle is set to 0-200℃, and the vacuum degassing time is 1h-72h. The temperature of the coagulation bath is -60 to 70°C, the ultraviolet light is configured with a wavelength of 200 to 400 nm, an intensity of 20 to 150 W, and an ultraviolet light irradiation time of 5 to 180 s; The stretching is 0.1 to 50 times, the heat setting temperature is 20 to 300°C, and the water washing temperature is 10 to 100°C.

15. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 14, characterized in that, The polyvinyl alcohol has a dissolution temperature of 40–150°C and a concentration of 1%–40% in the prepared polyvinyl alcohol solution. The concentration of the acidic reagent solution is 5% to 40%, and the pH of the reaction solution is adjusted to 0.5 to 5. The molar ratio of the alkyl aldehyde solution to the polyvinyl alcohol side chain hydroxyl group is 0.001–0.5, and the concentration is 5%–40%. The unsuitable solvent is 1 to 40 times the volume of the reaction liquid; The concentration of the alkaline reagent solution is 5% to 40%, and the pH of the reaction solution is adjusted to 3 to 11. The concentration of the solution prepared by dissolving the alkylated polyvinyl alcohol in the good solvent is 0.5% to 80%. The molar ratio of the photosensitive molecular solution to the alkylated polyvinyl alcohol side chain hydroxyl groups is 0.001–0.5, and the concentration is 5%–40%. The temperature of the filtrate squeezed into the degassing kettle is set to 40-150°C, and the vacuum degassing time is 6-24 hours. The temperature of the coagulation bath is -40 to 20°C, the ultraviolet light is configured with a wavelength of 365 nm, an intensity of 50 to 100 W, and an ultraviolet light irradiation time of 10 to 120 s; The stretching is 1 to 30 times, the heat setting temperature is 80 to 200°C, and the washing temperature is 50 to 90°C.

16. The method for preparing a rapidly photocrosslinkable, swelling-resistant, high-strength polyvinyl alcohol hydrogel according to claim 14, characterized in that, The polyvinyl alcohol has a dissolution temperature of 80–100°C and a concentration of 5%–15% in the prepared polyvinyl alcohol solution. The acidic reagent is hydrochloric acid or trifluoroacetic acid, and the concentration of the acidic reagent solution is 10% to 30%, adjusting the pH of the reaction solution to 1 to 3; The alkyl aldehyde is dodecaldehyde, and the molar ratio of the alkyl aldehyde solution to the side chain hydroxyl groups of polyvinyl alcohol is 0.005 to 0.05, with a concentration of 10% to 20%. The unsuitable solvent is ethanol or acetone, and the unsuitable solvent is 2 to 10 times the volume of the reaction liquid; The alkaline reagent is triethylamine or sodium hydroxide, the concentration of the alkaline reagent solution is 10% to 30%, and the pH of the reaction solution is adjusted to 6 to 8. The concentration of the solution prepared by dissolving the alkylated polyvinyl alcohol in the good solvent is 0.5% to 80%. The photosensitive molecule is methacrylic anhydride, and the molar ratio of the photosensitive molecule solution to the hydroxyl side chain of alkylated polyvinyl alcohol is 0.01 to 0.1, with a concentration of 10% to 30%. The temperature of the filtrate squeezed into the degassing kettle is set to 60-90°C, and the vacuum degassing time is 3-10 hours. The coagulation bath component is ethylene glycol monomethyl ether, the temperature of the coagulation bath is -30 to -10°C, the ultraviolet light is configured with a wavelength of 365 nm, an intensity of 80 W, and an ultraviolet light irradiation time of 30 s to 90 s; The stretching is 5 to 10 times, the heat setting temperature is 140 to 180°C, and the washing temperature is 80 to 95°C.

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