Hydrogel composite water-resistant moisture-absorbing film as well as preparation method and application thereof

Abstract

The invention provides a hydrogel composite water-resistant moisture-absorbing film as well as a preparation method and application thereof. The hydrogel composite water-resistant moisture-absorbing film comprises a composite hydrogel layer located inside and a protective layer located outside. The composite hydrogel layer comprises a cross-linked network formed by combining modified polyurethane and comonomers through covalent bonds. The prepared hydrogel composite water-resistant moisture-absorbing film has better mechanical properties, is not easy to deform and damage due to pulling, has better moisture absorption performance, can clean absorbed liquid in time, and can still keep higher mechanical properties after absorbing moisture.

Description

Technical Field

[0001] This invention relates to the field of medical materials, and more specifically, to a hydrogel composite water-resistant and moisture-absorbing film, its preparation method, and its application. Background Technology

[0002] The tympanic membrane plays a vital role in conducting, pressurizing, and protecting the middle and inner ear. However, it is very fragile and easily damaged by external factors such as trauma or bacterial invasion, or by internal factors such as upper respiratory tract infection or otitis media. This can lead to conditions such as tympanic membrane perforation, tympanic membrane retraction, and acute or chronic inflammation, resulting in ear discharge, hearing loss, tinnitus, headache, and dizziness, which seriously affect normal life. Treatment methods include puncture drainage, insertion of a tympanic membrane ventilation tube, and administration of antibiotics.

[0003] During the recovery period after treatment, if external dust, bacteria, or water enters the ear canal and comes into contact with the affected area, it may worsen the condition. Currently, ear patches on the market commonly use polyurethane or silicone as a single component, primarily for external protection. They achieve an internal and external barrier by sealing the outer contour of the ear. However, when there is pus discharge, using these ear patches can prevent the pus from draining in time, leading to internal fluid accumulation and hindering eardrum recovery. Furthermore, if fluid seeps through the ear patch, it cannot be cleaned and absorbed promptly. Also, ear patches made of polyurethane or silicone have poor mechanical properties; they lose their protective effect after being stretched, deformed, or damaged. Single-component gel films experience a rapid decline in mechanical properties after absorbing moisture. These issues require further improvement.

[0004] Therefore, it is necessary to develop a hydrogel film that has good mechanical properties, is not easily stretched or deformed, has good moisture absorption properties, can clean up absorbed liquids in time, and can still maintain high mechanical properties after absorbing moisture. Summary of the Invention

[0005] To address the technical problems existing in the prior art, this invention provides a hydrogel composite water-resistant and moisture-absorbing film, its preparation method, and its application.

[0006] This invention first prepares modified polyurethane, and then uses free radical polymerization of the modified polyurethane with monomers such as acrylamide to form a multi-component hydrogel crosslinking network to prepare a moisture-absorbing layer. The hydrophilic segment can effectively improve the functionality, while the hydrophobic segment is conducive to bonding with the water-resistant layer at the hot-press interface. Finally, a hydrogel composite water-resistant and moisture-absorbing film is prepared. The obtained hydrogel composite water-resistant and moisture-absorbing film is waterproof, dustproof and bacteria-resistant on the outside, absorbs wound pus on the inside, has good strength and tensile resistance, and effectively solves practical problems.

[0007] One of the objectives of this invention is to provide a hydrogel composite water-resistant and moisture-absorbing film.

[0008] The hydrogel composite water-resistant and moisture-absorbing film includes an inner composite hydrogel layer and an outer protective layer; the composite hydrogel layer includes a cross-linked network formed by modified polyurethane and comonomers bonded by covalent bonds.

[0009] Modified polyurethane, after modification, carries hydrophilic and crosslinking groups. On the one hand, the hydrophilic groups help it to dissolve in water and polymerize in the aqueous phase. On the other hand, the crosslinking groups can polymerize with comonomers under the action of additives. The hydrophobic segments of modified polyurethane can maintain hydrophobic properties, which is beneficial for hot pressing with thermoplastic polyurethane elastomer films and provides moisture absorption properties.

[0010] In a preferred embodiment of the present invention,

[0011] The protective layer is a thermoplastic polyurethane elastomer, preferably at least one of polyester-type polyurethane elastomer and polyether-type polyurethane elastomer; the thermoplastic polyurethane elastomer can provide mechanical support, and at the same time, during hot pressing, it interacts with the soft and hard segments of the modified polyurethane in the internal composite hydrogel layer, resulting in better bonding.

[0012] The modified polyurethane contains hydrophilic groups and copolymer crosslinking groups; the hydrophilic groups are at least one of carboxyl groups and sulfonic acid groups; the copolymer crosslinking groups are modified groups, preferably at least one of hydroxyl groups and double bonds; more preferably, the modified polyurethane is obtained by reacting components including polyether polyol, polyisocyanate, chain extender, and modifier in the presence of a catalyst.

[0013] The comonomer is at least one of acrylamide, acrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

[0014] The second objective of this invention is to provide a method for preparing a hydrogel composite water-resistant and moisture-absorbing film, comprising the following steps:

[0015] (1) Prepare an aqueous solution of the comonomer;

[0016] (2) The components including polyether polyol, polyisocyanate, chain extender and modifier are reacted in the presence of a catalyst to obtain modified polyurethane;

[0017] (3) Prepare an aqueous solution of initiator and crosslinking agent;

[0018] (4) Under a protective gas atmosphere, triethylamine and the aqueous solution of the comonomer obtained in step (1) are added to the modified polyurethane obtained in step (2), and then the aqueous solution of the initiator and crosslinking agent obtained in step (3) is added. After the crosslinking reaction, the composite hydrogel layer is obtained.

[0019] (5) The composite hydrogel layer obtained in step (4) is hot-pressed with the protective layer to obtain the hydrogel composite water-resistant and moisture-absorbing film.

[0020] Triethylamine's main function is to ionize carboxyl groups, and it also helps with dispersion and end-capping in water.

[0021] In a preferred embodiment of the present invention,

[0022] Step (1),

[0023] The total concentration of the aqueous solution of the comonomer is 1-40 wt%, preferably 5-30 wt%; for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or any two of the above values, such as 10-30 wt%; the comonomer can be one or a combination of several, such as two or three, and the concentration of each comonomer is 1-20 wt%, preferably 3-15 wt%;

[0024] Heat and stir until completely dissolved, then cool to room temperature before use.

[0025] In a preferred embodiment of the present invention,

[0026] Step (2),

[0027] First, polyether polyol and polyisocyanate are prepolymerized in the presence of a catalyst under a protective gas atmosphere. Then, a chain extender is added to carry out reaction A, and a modifier is added to carry out reaction B under an air atmosphere.

[0028] The polyether polyol is at least one of polyethylene glycol, polypropylene glycol, polyethylene glycol monomethyl ether, and polyethylene glycol monobutyl ether;

[0029] The polyisocyanate is a diisocyanate, preferably at least one of hexamethylene diisocyanate, toluene diisocyanate, and isophorone diisocyanate, more preferably at least two;

[0030] The chain extender is at least one selected from 1,4-butanediol, ethylene glycol, propylene glycol, trihydroxypropane, and dimethylolpropionic acid.

[0031] The modifier is at least one of allyl alcohol and its silane derivatives, hydroxypropyl methacrylate, hydroxypropyl acrylate, and sodium ethylenediamine ethanesulfonate.

[0032] The catalyst is at least one of trimethyltin, trioctyltin, dibutyltin dilaurate, bismuth isooctanoate, bismuth laurate, and bismuth neodecanoate.

[0033] The mass ratio of the polyether polyol to the polyisocyanate is (0.3–1.1):1, preferably (0.3–0.8):1;

[0034] The mass ratio of the chain extender to the polyisocyanate is (0.01-0.1):1, preferably (0.05-0.1):1;

[0035] The mass ratio of the modifier to the polyisocyanate is (0.05-0.5):1, preferably (0.1-0.25):1;

[0036] The amount of catalyst used is 0.05 to 0.5 wt% of the total mass of the reactants, preferably 0.08 to 0.13 wt%.

[0037] Preferably,

[0038] The protective gas is at least one of nitrogen and inert gas;

[0039] The prepolymerization temperature is 50–80°C, and the prepolymerization time is 30–60 min;

[0040] The temperature of reaction A is 60–80℃, and the reaction time is 10–60 min;

[0041] The temperature of reaction B is 50–70℃, and the reaction time is 10–30 min.

[0042] In a preferred embodiment of the present invention,

[0043] Step (3),

[0044] The initiator is at least one of ammonium persulfate, potassium persulfate, sodium metabisulfite, and sodium bisulfite;

[0045] The crosslinking agent is at least one of N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and glutaraldehyde.

[0046] The concentration of the aqueous solution of the initiator is 0.01–1 wt%, preferably 0.1–0.5 wt%.

[0047] The concentration of the crosslinking agent in the aqueous solution is 0.005–1 wt%, preferably 0.01–0.1 wt%.

[0048] Stirring ensures that the initiator and crosslinking agent are completely dissolved in the water.

[0049] In a preferred embodiment of the present invention,

[0050] Step (4),

[0051] The mass ratio of the modified polyurethane, triethylamine, and comonomer aqueous solution is 1:(0.1-1):(1-6), preferably 1:(0.1-0.5):(3-5);

[0052] The amount of the initiator is 100 to 1000 ppm of the comonomer, preferably 300 to 600 ppm;

[0053] The amount of the crosslinking agent is 5 to 200 ppm of the comonomer, preferably 10 to 50 ppm;

[0054] The ppm concentration of initiators or crosslinkers based on comonomers refers to the concentration of the initiator or crosslinker by mass in parts per million (ppm) of the comonomer.

[0055] The comonomer aqueous solution is added to the modified polyurethane by dripping, and the dripping rate is more preferably carried out by using a peristaltic pump at 5-15 mL / min;

[0056] After the addition is complete, the mixing time of the modified polyurethane, triethylamine, and comonomer aqueous solution is 1-3 hours, the mixing temperature is 30-40℃, and the mixing is completed under stirring.

[0057] After mixing, cool to room temperature before adding the aqueous solution of initiator and crosslinking agent;

[0058] The cross-linking reaction temperature is 40–60℃, and the cross-linking reaction time is 1–3 hours.

[0059] After the crosslinking reaction, the product is soaked in a solvent; more preferably, the solvent is deionized water; and / or, the soaking time is 24 to 72 hours (soaking time refers to the soaking time of one soaking); the number of soakings is 3 to 6 (the solvent needs to be changed for a second soaking after each soaking); after soaking, the product is taken out and vacuum dried.

[0060] In a preferred embodiment of the present invention,

[0061] Step (5),

[0062] The proportion of hard segments in the thermoplastic polyurethane elastomer is 10-60 wt%, preferably 20-50 wt%.

[0063] The mass ratio of the composite hydrogel layer to the thermoplastic polyurethane elastomer is 10:90 to 90:10, preferably 20:80 to 40:60;

[0064] The hot pressing temperature is 120–150℃;

[0065] The hot pressing time is 5 to 20 minutes;

[0066] The thickness of the hydrogel composite water-resistant and moisture-absorbing film is 1-5 mm;

[0067] Rapid cooling process after hot pressing.

[0068] The third objective of this invention is to provide a hydrogel composite water-resistant and moisture-absorbing film obtained by the above preparation method.

[0069] The fourth objective of this invention is to provide an application of a hydrogel composite water-resistant and moisture-absorbing film in the medical field, preferably in the treatment of tympanic membranes.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0071] This invention first involves free radical polymerization of modified polyurethane and acrylamide to form a two-component hydrogel crosslinking network to prepare a moisture-absorbing layer. The hydrophilic segment effectively improves functionality, while the hydrophobic segment facilitates bonding with the water-resistant layer at the hot-press interface. Ultimately, a hydrogel composite water-resistant and moisture-absorbing film is prepared. The resulting hydrogel composite water-resistant and moisture-absorbing film is waterproof, dustproof, and antibacterial on the outside, absorbs wound pus on the inside, has good strength, and is resistant to tensile stress, effectively solving practical problems.

[0072] This invention improves the compatibility of hydrogel and thermoplastic polyurethane through prepolymer copolymerization modification. The combination of the two significantly improves mechanical strength and water resistance, while giving the film moisture-absorbing functionality. It also avoids the rapid decline in mechanical properties after water absorption by a single hydrogel, solving the problems of existing single-component ear patches that cannot absorb moisture, have rapid decline in mechanical properties after moisture absorption, and are prone to deformation, breakage and failure. Detailed Implementation

[0073] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0074] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0075] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0076] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0077] The thermoplastic polyurethane elastomer film is a polyether-type polyurethane elastomer manufactured by KRAIBURG TPE.

[0078] Test method:

[0079] Water pressure resistance test: The hydrostatic pressure tester is used to test the water pressure resistance tester. A 200×200×3mm sample is cut and placed in the test area under no tension. The distilled water pressure is adjusted to 6kPa / min. When 3 water droplets appear at different positions on the sample surface, the test ends and the water pressure value at this time is recorded. Each sample is tested at least 5 times.

[0080] Moisture absorption test: Cut a 10×10×3mm sample and place it in a petri dish. Add physiological saline to the film. The end standard is when the film can no longer absorb the liquid or the liquid overflows. Weigh the film before and after the test and calculate the difference in liquid weight that each gram of film can absorb.

[0081] Tear test: Refer to GB / T529 and use an electronic universal testing machine to test the tear performance of the sample.

[0082]

Example 1

[0083] Step (1): Prepare aqueous solutions of acrylamide and acrylic acid monomer (15 wt%), heat and stir to completely dissolve them, and then cool to room temperature to obtain an aqueous solution of comonomer for later use.

[0084] Step (2): Add 10g of isophorone diisocyanate, 15g of toluene diisocyanate, 15g of polyethylene glycol, and 0.05g of dibutyltin dilaurate to a water bath round-bottom flask. Heat the mixture to 80°C and stir for 60 minutes under a nitrogen atmosphere. Add 1g of dimethylolpropionic acid and 1.5g of butanediol to the flask and continue stirring at 80°C for 30 minutes. Stop the nitrogen flow and add 3g of hydroxypropyl methacrylate to the flask. React at 50°C under an air atmosphere for 10 minutes to obtain a modified polyurethane emulsion.

[0085] Step (3): Prepare an aqueous solution of sodium bisulfite (0.1 wt%) and a mixed aqueous solution of potassium persulfate (0.1 wt%) and N,N'-methylenebisacrylamide (0.01 wt%), and stir until completely dissolved.

[0086] Step (4): Take 10g of the modified polyurethane obtained in step (2) into a flask, introduce nitrogen gas, add 1g of triethylamine, and slowly add 30g of the aqueous solution of the comonomer obtained in step (1) to the flask. The dropping rate is 10ml / min using a peristaltic pump. After the dropping is completed, continue stirring the mixture at 30℃ for 1h. Then stop the nitrogen gas and stirring, transfer it to a nitrogen blowing mold and cool it to room temperature. Add the mixed aqueous solution obtained in step (3) to 250ppm (based on the comonomer, i.e., the ratio of the total mass of potassium persulfate and N,N'-methylenebisacrylamide in the mixed solution to the mass of the comonomer). Introduce sodium bisulfite aqueous solution to 300ppm (based on the comonomer, i.e., the ratio of the mass of sodium bisulfite to the mass of the comonomer). Stop the dropping after the reaction temperature rises to 50℃. Then keep it at the temperature and stand for 2h to crosslink the product hydrogel layer. The hydrogel layer of the product was removed and soaked in deionized water for 24 hours. Then the deionized water was replaced and the soaking was continued. This process was repeated three times. After removal, the product was vacuum dried to obtain the composite hydrogel layer.

[0087] Step (5): Take a thermoplastic polyurethane elastomer film with a hard segment ratio of 30wt%, cover it with a composite hydrogel layer, and the mass ratio of thermoplastic polyurethane elastomer to composite hydrogel layer is 20:80. Use a 3mm thick mold to hot press at 130℃ for 15min, and then use rapid cooling treatment to finally obtain a hydrogel composite polyurethane film.

[0088]

Example 2

[0089] Step (1): Prepare aqueous solutions of acrylamide and acrylic acid monomer (5 wt%), heat and stir to completely dissolve them, and then cool to room temperature to obtain an aqueous solution of comonomer for later use.

[0090] Step (2): Add 20g isophorone diisocyanate, 30g toluene diisocyanate, 15g polyethylene glycol, and 0.08g dibutyltin dilaurate to a water bath round-bottom flask. Heat the mixture to 80°C and stir for 60 minutes under a nitrogen atmosphere. Add 1.5g dimethylolpropionic acid and 1.5g butanediol to the flask and continue stirring at 80°C for 50 minutes. Stop the nitrogen flow and add 5g hydroxypropyl methacrylate to the flask. React at 50°C under an air atmosphere for 20 minutes to obtain a modified polyurethane emulsion.

[0091] Step (3): Prepare aqueous solutions of sodium bisulfite (0.1 wt%) and potassium persulfate (0.1 wt%) mixed with N,N'-methylenebisacrylamide (0.01 wt%), and stir until completely dissolved.

[0092] Step (4): Take 10g of the modified polyurethane obtained in step (2) into a flask, introduce nitrogen gas, add 1g of triethylamine, and slowly add 30g of the aqueous solution of the comonomer obtained in step (1) to the flask (note that the amount of the above three raw materials must comply with the limitation of claim 6). The dropping speed is 10ml / min using a peristaltic pump. After the dropping is completed, continue to stir the mixture at 30°C for 1h. Then stop the nitrogen gas and stirring, transfer it to a nitrogen blowing mold and cool it to room temperature. Add the mixed aqueous solution obtained in step (3) to 150ppm (based on the comonomer, i.e., the ratio of the total mass of potassium persulfate and N,N'-methylenebisacrylamide in the mixed solution to the mass of the comonomer). Add sodium bisulfite aqueous solution to 200ppm (based on the comonomer, i.e., the ratio of the mass of sodium bisulfite to the mass of the comonomer). Stop the dropping after the reaction temperature rises to 40°C. Then keep it at the temperature and stand for 3h to obtain the product hydrogel layer after the crosslinking reaction. The hydrogel layer of the product was removed and soaked in deionized water for 24 hours. Then the deionized water was replaced and the soaking was continued. This process was repeated three times. After removal, the product was vacuum dried to obtain the composite hydrogel layer.

[0093] Step (5): Take a thermoplastic polyurethane elastomer film with a hard segment ratio of 30wt%, cover it with a composite hydrogel layer, and the mass ratio of thermoplastic polyurethane elastomer to composite hydrogel layer is 20:80. Use a 3mm thick mold to hot press at 130℃ for 15min, and then use rapid cooling treatment to finally obtain a hydrogel composite polyurethane film.

[0094]

Example 3

[0095] Step (1): Prepare aqueous solutions of acrylamide and acrylic acid monomer (5 wt%), heat and stir to completely dissolve them, and then cool to room temperature to obtain an aqueous solution of comonomer for later use.

[0096] Step (2): Add 5g isophorone diisocyanate, 15g toluene diisocyanate, 15g polyethylene glycol, and 0.035g dibutyltin dilaurate to a water bath round-bottom flask. Heat the mixture to 50°C and stir for 30 minutes under a nitrogen atmosphere. Add 0.5g dimethylolpropionic acid and 1g butanediol to the flask and maintain the temperature at 80°C. Continue stirring for 30 minutes. Stop the nitrogen flow and add 5g hydroxypropyl methacrylate to the flask. React at 50°C under an air atmosphere for 10 minutes to obtain a modified polyurethane emulsion.

[0097] Step (3): Prepare aqueous solutions of sodium bisulfite (0.1 wt%) and potassium persulfate (0.1 wt%) mixed with N,N'-methylenebisacrylamide (0.01 wt%), and stir until completely dissolved.

[0098] Step (4): Take 2g of the modified polyurethane obtained in step (2) into a flask, introduce nitrogen gas, add 1g of triethylamine, and slowly add 10g of the aqueous solution of the comonomer obtained in step (1) to the flask (note that the amount of the above three raw materials must comply with the limitation of claim 6). The dropping speed is 10ml / min using a peristaltic pump. After the dropping is completed, continue to stir the mixture at 30°C for 1h. Then stop the nitrogen gas and stirring, transfer it to a nitrogen blowing mold and cool it to room temperature. Add the mixed aqueous solution obtained in step (3) to 150ppm (based on the comonomer, i.e., the ratio of the total mass of potassium persulfate and N,N'-methylenebisacrylamide in the mixed solution to the mass of the comonomer). Add sodium bisulfite aqueous solution to 200ppm (based on the comonomer, i.e., the ratio of the mass of sodium bisulfite to the mass of the comonomer). After the reaction temperature is raised to 40°C, stop the dropping. Then keep it warm and stand for 1h to obtain the product hydrogel layer after the crosslinking reaction. The hydrogel layer of the product was removed and soaked in deionized water for 24 hours. Then the deionized water was replaced and the soaking was continued. This process was repeated three times. After removal, the product was vacuum dried to obtain the composite hydrogel layer.

[0099] Step (5): Take a thermoplastic polyurethane elastomer film with a hard segment ratio of 30wt%, cover it with a composite hydrogel layer, and the mass ratio of thermoplastic polyurethane elastomer to composite hydrogel layer is 40:60. Use a 3mm thick mold to hot press at 150℃ for 5min, and then use rapid cooling treatment to finally obtain a hydrogel composite polyurethane film.

[0100] Comparative Example 1

[0101] The difference from Example 1 is that hydrogel composite is not used. Instead, a thermoplastic polyurethane elastomer film with a hard segment ratio of 30wt% is directly used. The film is hot-pressed at 130°C for 15 minutes using a 3mm thick mold, followed by rapid cooling treatment to finally obtain a polyurethane film.

[0102] Comparative Example 2

[0103] The difference from Example 1 is that polyurethane membrane composite is not used. Instead, the composite hydrogel layer prepared in Example 1 is used directly as the hydrogel membrane. That is, in step (5), the obtained composite hydrogel layer is hot-pressed at 130°C for 15 minutes using a 3 mm thick mold, and then subjected to rapid cooling treatment to finally obtain the composite hydrogel film.

[0104] Comparative Example 3

[0105] The difference from Example 1 is that step (2) to prepare modified polyurethane is omitted. Instead, in step (4), an aqueous solution of the comonomer obtained in step (1) is added dropwise to triethylamine, and then a polyacrylamide-acrylic hydrogel layer is obtained. Then, in step (5), the polyacrylamide-acrylic hydrogel layer is used to replace the composite hydrogel layer to obtain a hydrogel composite polyurethane film.

[0106] The performance of the samples was tested as follows:

[0107] Water pressure resistance test: The hydrostatic pressure tester was used. A 200×200×3mm sample was cut and placed in the test area under no tension. The distilled water pressure was increased to 6 kPa / min. The test ended when 3 water droplets appeared at different positions on the sample surface. The water pressure value at this time was recorded. Each sample was tested at least 5 times. The average value of the test results is shown in Table 1 below.

[0108] Table 1

[0109]

[0110] If the external liquid in the hydrogel composite water-resistant and moisture-absorbing film is flowing slowly, it can be removed through moisture absorption; if it is flowing rapidly, such as by sputtering, it needs to have water pressure resistance. As shown in Table 1, compared with Comparative Examples 1 to 3, the water pressure resistance of Example 1 is significantly better. The water pressure resistance of Examples 1 to 3 is between 9.8 and 13.5 kPa, all of which have good water pressure resistance.

[0111] Moisture absorption test: Cut a 10×10×3mm sample and place it in a petri dish. Add physiological saline to the film. The end standard is when the film can no longer absorb or the liquid overflows. Weigh the film before and after the test and calculate the difference in liquid weight that each g of film can absorb. The results are shown in Table 2 below.

[0112] Table 2

[0113]

[0114] As shown in Table 2, Comparative Example 2 is a pure hydrogel layer, which should theoretically have the best moisture absorption. However, the water absorption of Example 1 decreased by only about 8% compared to Comparative Example 2, proving that the water absorption capacity is well maintained after the composite hydrogel layer and the protective layer are combined.

[0115] Compared with Example 1, the water absorption of Example 1 is 88% higher than that of Comparative Example 3, proving that the modified polyurethane copolymer interpenetrating crosslinked network composite hydrogel layer of the present invention has better water absorption capacity than the polyacrylamide-acrylic hydrogel layer of the prior art.

[0116] Tear test: The tear performance of the samples was tested using an electronic universal testing machine in accordance with GB / T529. The results are shown in Table 3.

[0117] Table 3

[0118]

[0119] As shown in Table 3, before moisture absorption, the tear performance of Example 1 was higher than that of Comparative Example 1. This is because the composite material was prepared by compression, resulting in interlocking of soft and hard segments and higher tear strength. The tear performance of Comparative Example 2 decreased significantly after moisture absorption, and the tear strength of Comparative Example 3 before and after moisture absorption was significantly lower than that of Example 1. This demonstrates that adding modified polyurethane during polymerization can significantly improve the mechanical properties of the composite film before and after moisture absorption.

[0120] The hydrogel composite water-resistant and moisture-absorbing films prepared in Examples 1-3, through prepolymer copolymerization modification to improve the compatibility between the hydrogel and thermoplastic polyurethane, significantly enhance mechanical strength and water resistance. Simultaneously, they impart moisture-absorbing functionality to the film, avoiding the rapid decline in mechanical properties after water absorption by a single hydrogel. This solves the problems of existing single-component ear patches, such as inability to absorb moisture, rapid decline in mechanical properties after moisture absorption, and easy deformation and breakage. The resulting hydrogel composite water-resistant and moisture-absorbing film is externally waterproof, dustproof, and antibacterial, internally absorbs wound pus, has good strength, and is tensile-resistant, effectively solving practical problems.

Claims

1. A hydrogel composite water-resistant and moisture-absorbing film, comprising an inner composite hydrogel layer and an outer protective layer; the composite hydrogel layer comprising a cross-linked network formed by modified polyurethane and comonomers bonded by covalent bonds.

2. The hydrogel composite water-resistant and moisture-absorbing film as described in claim 1, characterized in that: The protective layer is a thermoplastic polyurethane elastomer, preferably at least one of polyester-type polyurethane elastomer and polyether-type polyurethane elastomer; and / or, The modified polyurethane contains hydrophilic groups and copolymer crosslinking groups; the hydrophilic groups are at least one of carboxyl groups and sulfonic acid groups; the copolymer crosslinking groups are modified groups, preferably at least one of hydroxyl groups and double bonds; more preferably, the modified polyurethane is obtained by reacting components including polyether polyol, polyisocyanate, chain extender, and modifier in the presence of a catalyst; and / or, The comonomer is at least one of acrylamide, acrylic acid, and 2-acrylamide-2-methylpropanesulfonic acid.

3. A method for preparing a hydrogel composite water-resistant and moisture-absorbing film as described in claim 1 or 2, comprising the following steps: (1) Prepare an aqueous solution of the comonomer; (2) The components including polyether polyol, polyisocyanate, chain extender and modifier are reacted in the presence of a catalyst to obtain modified polyurethane; (3) Prepare an aqueous solution of initiator and crosslinking agent; (4) Under a protective gas atmosphere, triethylamine and the aqueous solution of the comonomer obtained in step (1) are added to the modified polyurethane obtained in step (2), and then the aqueous solution of the initiator and crosslinking agent obtained in step (3) is added. After the crosslinking reaction, the composite hydrogel layer is obtained. (5) The composite hydrogel layer obtained in step (4) is hot-pressed with the protective layer to obtain the hydrogel composite water-resistant and moisture-absorbing film.

4. The method for preparing the hydrogel composite water-resistant and moisture-absorbing film as described in claim 3, characterized in that: Step (1), The total concentration of the aqueous solution of the comonomer is 1–40 wt%, preferably 5–30 wt%; and / or, Heat and stir until completely dissolved, then cool to room temperature before use.

5. The method for preparing the hydrogel composite water-resistant and moisture-absorbing film as described in claim 3, characterized in that: Step (2), First, prepolymerize polyether polyol and polyisocyanate in the presence of a catalyst under a protective gas atmosphere, then add a chain extender to carry out reaction A, followed by adding a modifier to carry out reaction B under an air atmosphere; and / or, The polyether polyol is at least one selected from polyethylene glycol, polypropylene glycol, polyethylene glycol monomethyl ether, and polyethylene glycol monobutyl ether; and / or, The polyisocyanate is a diisocyanate, preferably at least one of hexamethylene diisocyanate, toluene diisocyanate, and isophorone diisocyanate, more preferably at least two; and / or The chain extender is at least one selected from 1,4-butanediol, ethylene glycol, propylene glycol, trihydroxypropane, and dimethylolpropionic acid; and / or, The modifier is at least one selected from allyl alcohol and its silane derivatives, hydroxypropyl methacrylate, hydroxypropyl acrylate, and sodium ethylenediamine ethanesulfonate; and / or, The catalyst is at least one of trimethyltin, trioctyltin, dibutyltin dilaurate, bismuth isooctanoate, bismuth laurate, and bismuth neodecanoate. The mass ratio of the polyether polyol to the polyisocyanate is (0.3–1.1):1, preferably (0.3–0.8):1; and / or, The mass ratio of the chain extender to the polyisocyanate is (0.01–0.1):1, preferably (0.05–0.1):1; and / or, The mass ratio of the modifier to the polyisocyanate is (0.05–0.5):1, preferably (0.1–0.25):1; and / or, The catalyst is used in an amount of 0.05–0.5 wt% of the total mass of the reactants, preferably 0.08–0.13 wt%; and / or, Preferably, The protective gas is at least one of nitrogen and an inert gas; and / or, The prepolymerization temperature is 50–80°C, and the prepolymerization time is 30–60 min; and / or, The temperature of reaction A is 60–80℃, and the reaction time is 10–60 min; and / or, The temperature of reaction B is 50–70℃, and the reaction time is 10–30 min.

6. The method for preparing the hydrogel composite water-resistant and moisture-absorbing film as described in claim 3, characterized in that: Step (3), The initiator is at least one of ammonium persulfate, potassium persulfate, sodium metabisulfite, and sodium bisulfite; and / or, The crosslinking agent is at least one selected from N,N'-methylenebisacrylamide, polyethylene glycol diacrylate, and glutaraldehyde; and / or... The concentration of the initiator in aqueous solution is 0.01–1 wt%, preferably 0.1–0.5 wt%; and / or, The concentration of the crosslinking agent in the aqueous solution is 0.005–1 wt%, preferably 0.01–0.1 wt%; and / or, Stirring ensures that the initiator and crosslinking agent are completely dissolved in the water.

7. The method for preparing the hydrogel composite water-resistant and moisture-absorbing film as described in claim 3, characterized in that: Step (4), The mass ratio of the modified polyurethane, triethylamine, and comonomer aqueous solution is 1:(0.1-1):(1-6), preferably 1:(0.1-0.5):(3-5); and / or, The amount of the initiator is 100-1000 ppm of the comonomer, preferably 300-600 ppm; and / or, The amount of the crosslinking agent is 5-200 ppm of the comonomer, preferably 10-50 ppm; and / or, The comonomer aqueous solution is added to the modified polyurethane by dropwise addition, preferably using a peristaltic pump at a rate of 5–15 mL / min; and / or, After the addition is complete, the mixing time for the modified polyurethane, triethylamine, and comonomer aqueous solution is 1–3 hours, the mixing temperature is 30–40°C, and the mixing is completed under stirring; and / or, After mixing, cool to room temperature before adding the aqueous solution of initiator and crosslinking agent; and / or, The cross-linking reaction temperature is 40–60℃, and the cross-linking reaction time is 1–3 h; and / or, After the crosslinking reaction, the product is soaked in a solvent; more preferably, the solvent is deionized water; and / or, the soaking time is 24 to 72 hours; and / or, the number of soaking times is 3 to 6; after soaking, the product is vacuum dried.

8. The method for preparing the hydrogel composite water-resistant and moisture-absorbing film as described in claim 3, characterized in that: Step (5), The hard segment proportion of the thermoplastic polyurethane elastomer is 10–60 wt%, preferably 20–50 wt%; and / or, The mass ratio of the composite hydrogel layer to the thermoplastic polyurethane elastomer is 10:90 to 90:10, preferably 20:80 to 40:60; and / or, The hot pressing temperature is 120–150°C; and / or, The hot pressing time is 5–20 minutes; and / or, The thickness of the hydrogel composite water-resistant and moisture-absorbing film is 1–5 mm; and / or, Cooling treatment after hot pressing.

9. A hydrogel composite water-resistant and moisture-absorbing film obtained by the preparation method according to any one of claims 3 to 8.

10. The application of a hydrogel composite water-resistant and moisture-absorbing film as described in any one of claims 1 to 2, 9 in the medical field, preferably in the treatment of tympanic membranes.

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