A hydrogel coating, preparation method and application

Abstract

The present invention belongs to the field of material technology, and discloses a hydrogel coating, a spraying method and an application. The spraying method comprises the following steps: (1) Using a high-voltage electrostatic spray gun, spraying hydrogel coating powder on the surface of a substrate material; (2) Spraying a solution on the surface of the substrate material to redissolve the hydrogel coating and form a hydrogel coating. In the present invention, the hydrogel coating powder is electrostatically adsorbed and sprayed on the surface of the substrate by electrostatic spraying first, and then water is sprayed to redissolve it. The hydrogel undergoes preliminary self-gelation through hydrogen bond action and binds to the base material, and then further binds through dynamic covalent bonds to form a hydrogel coating. The coating conditions are simple, the coating is fast, and there is no need for ultraviolet light irradiation, anaerobic environment, heating, molds, etc. during the coating process, breaking through the limitations of the polymerization and crosslinking conditions of hydrogels on traditional hydrogel coatings.

Description

Technical Field

[0001] The present invention belongs to the field of material technology, relates to surface processing and coatings, and in particular to a hydrogel coating, a preparation method and an application thereof. Background Art

[0002] The existing hydrogel coating technology has harsh conditions. Generally, the substrate material is pretreated first, then the hydrogel precursor solution is applied to the matrix, and then in-situ polymerization crosslinking is carried out (including small molecules polymerizing into long chains, long chains crosslinking into networks, and the networks forming links with the matrix material). This operation requires harsh conditions, such as surface pretreatment, anaerobic environment, ultraviolet light irradiation, use of molds, specific acid-base conditions or temperature changes, etc., and its scope of use and area of use are limited. In addition, in the existing hydrogel coating technology, brushing and dipping are mostly carried out with liquids. On complex surface devices, especially in parts such as corners, it is not easy to absorb the slurry and is prone to showing the base. And the hydrogel polymerized on the substrate has monomer residues, which are usually toxic substances and harmful to the human body. The hydrogel material has strong hydrophilicity, and the hydrogel coating formed by in-situ polymerization will absorb water and swell and deform in the solution.

[0003] Through retrieval, the following several patent literature related to the present invention patent application are found:

[0004] Patent document CN 110373069A discloses a hydrogel coating, a preparation method thereof and an application in reducing the freezing temperature and prolonging the freezing time. The hydrogel coating of the invention is prepared by alternately coating different polyelectrolytes on the surface of the substrate in a layer-by-layer assembly manner and forming a polyelectrolyte network structure through chemical crosslinking to achieve the purpose of reducing the freezing temperature and prolonging the freezing time. The polyelectrolytes are crosslinked by chemical bonds, and during the crosslinking process, the substrate needs to be immersed in a crosslinking agent solution under specific acid-base conditions, which is not suitable for large-scale application. And there will be monomer residues and water absorption and swelling deformation during in-situ polymerization.

[0005] Patent document CN113368315A discloses a medical nickel-titanium alloy material with a thermosensitive hydrogel coating, a preparation method thereof and an application. This method first prepares a porous titanium dioxide nanolayer by anodic oxidation, and then chemically grafts a polyisopropylacrylamide thermosensitive hydrogel onto the surface of the sample. However, this method requires pickling and thermal oxidation of the substrate, and then a thermosensitive hydrogel is formed by the polymerization of isopropylacrylamide. This method will have harmful monomer isopropylacrylamide residues (Problem 3) and water absorption and swelling deformation.

[0006] In addition, Hydrogel Paint discloses a method for coating a hydrogel paint. In this method, hydrogel monomers are polymerized with a silane coupling agent in advance to form a hydrogel paint. Then, the base material is pretreated with the silane coupling agent, painted on the base material, and then polymerized with each other and connected to the base material by reacting with a crosslinking agent. To a certain extent, this method avoids the harsh conditions for hydrogel polymerization. However, this method still requires pretreatment of the surface with a silane coupling agent, and the brushing method is not applicable to complex surfaces. Renatured hydrogel painting discloses a method for coating a regenerated hydrogel. In this method, the hydrogel is freeze-dried, ground into powder, then an adhesive is applied to the surface of the base material to stick the freeze-dried powder on the base material, and finally the hydrogel is regenerated by adding water to form a hydrogel coating. This method requires pretreatment of brushing an adhesive on the base material in advance, and this adhesive will introduce an intermediate layer, changing the mechanical properties of the hydrogel-substrate composite material.

[0007] Therefore, there is an urgent need to develop a simple and general hydrogel coating, preparation method and application. Summary of the Invention

[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a hydrogel coating, preparation method and application.

[0009] The technical solution adopted by the present invention to solve its technical problems is:

[0010] A method for coating a hydrogel, the method comprising the following steps:

[0011] (1) Using a high-voltage electrostatic spray gun, spraying hydrogel paint powder on the surface of the base material;

[0012] (2) Spraying a solution on the surface of the base material to redissolve the hydrogel paint powder and form a hydrogel coating.

[0013] Further, the preparation method of the hydrogel paint powder in step (1) is as follows:

[0014] S1. Prepare a viscous hydrogel and perform pretreatment;

[0015] S2. Grind into powder, freeze-dry, sieve, and perform vacuum plasma treatment for 5 - 15 min;

[0016] S3. Mix with functional powder to obtain.

[0017] Further, the viscous hydrogel in step S1 has self-healing properties and includes one or more of dynamic covalent bonds such as Schiff base rebonding, hydrazide rebonding, oxime rebonding, borate ester, phenylborate ester, and silanol condensation.

[0018] Furthermore, the viscous hydrogel is copolymerized from chitosan, 1-ethyl-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide, acrylic acid, α-ketoglutaric acid, and 3-methacryloxypropyltrimethoxysilane.

[0019] Furthermore, the ratio of chitosan, 1-ethyl-(3-dimethylaminopropyl) carbodiimide, N-hydroxysuccinimide, acrylic acid, α-ketoglutaric acid, and 3-methacryloxypropyltrimethoxysilane is g:g:g:mL:mL:μL = 0.56:0.28:0.12:20 - 40:5.6:20. Dissolve various viscous hydrogels in distilled water, and the ratio of chitosan to distilled water is g:mL = 0.56:100. Cure with ultraviolet light for 60 min to prepare the viscous hydrogel.

[0020] Furthermore, the hydrogel pretreatment is also included in step S1, including soaking in the working environment solution, and the working environment solution includes distilled water, physiological saline, digestive tract fluid, and seawater.

[0021] Furthermore, the functional powder in step S3 includes thermosensitive hydrogel dry powder, SiO2, nano magnetic particles, and medicinal powder;

[0022] Furthermore, the substrate material in step (2) includes various substrates such as metal, ceramic, wood, silica gel, glass, and skin;

[0023] Alternatively, the solution in step (2) includes various functional solutions such as salt solution, indicator solution, and organic water mixed solution.

[0024] The hydrogel coating prepared by the method as described above.

[0025] The application of the method as described above in surface processing and coating.

[0026] The advantages and positive effects obtained by the present invention are:

[0027] 1. The method of the present invention forms a hydrogel coating through a three-step method of "electrostatic - hydrogen bond - covalent bond", that is, first spray the hydrogel coating powder on the surface of the substrate by electrostatic adsorption using electrostatic spraying, then spray the solution for re-dissolution, and the hydrogel undergoes preliminary self-gelation by hydrogen bond action and binds to the base material, and then further combines with dynamic covalent bonds to form a hydrogel coating. The coating conditions are simple, the coating is fast, and there is no need for ultraviolet light irradiation, anaerobic environment, heating, molds, etc. during the coating process, breaking through the limitations of hydrogel polymerization and cross-linking conditions on traditional hydrogel coatings, and can be applied to large-area coatings.

[0028] 2. In the preparation process of the powder coating of the present invention, the hydrogel is ground into powder, freeze-dried, sieved, and subjected to vacuum plasma treatment, which increases the powder coating pickup rate from 87.4% ± 2.6% to 97.6% ± 2.1%.

[0029] 3. The present invention separates the two steps of hydrogel preparation and coating. The prepared hydrogel can be repeatedly soaked, and the residual acrylic monomer is reduced from 17.57 ± 1.8 mg / g by the traditional method to 0.18 ± 0.01 mg / g, avoiding the residual influence caused by harmful monomers.

[0030] 4. The hydrogel prepared by the method of the present invention can be pre-swollen in working environment solutions such as physiological saline and seawater, then powdered and freeze-dried, and then coated to avoid coating water absorption and deformation; the swelling rate of the coating is 7.48% ± 1.27%, effectively controlling the swelling rate of the coating in special solutions and reducing coating deformation.

[0031] 5. The present invention uses the dry powder spraying method to replace the liquid brushing for preparing the hydrogel coating. The hydrogel coating powder is initially electrostatically adsorbed on the object surface. Due to the tip effect of the charge, the powder is not easy to lose, and it is easier to form a uniform hydrogel coating on complex surfaces such as corners than liquid brushing.

[0032] 6. In the method of the present invention, since the hydrogel coating powder has strong hydrogen bonds and dynamic covalent bonds, it has self-adhesion and strong adhesion to various materials. It can absorb water and redissolve to form a hydrogel coating, firmly adhere to the substrate surface, and the coating adheres to the substrate surface in a point-bonding manner and is not easy to peel off.

[0033] 7. The method of the present invention coats in a point manner, having anti-tensile and variable properties; and has a wide application range. It can be doped with a variety of other materials and then sprayed to form functional hydrogel coatings with temperature response, pH response, water absorption, etc. Description of the Drawings

[0034] Figure 1 SEM image of the hydrogel coating of the preparation method in Example 1 of the present invention;

[0035] Figure 2 Comparison chart of the thickness data of the coatings at each part in Example 1 and Comparative Example 1 of the present invention;

[0036] Figure 3 Force-displacement curve during the coating peeling process in Example 1 and Comparative Example 2 of the present invention;

[0037] Figure 4 Comparison chart of the powder coating pickup rate of the hydrogel coating powder in Example 2 and Example 1 of the present invention;

[0038] Figure 5Graph showing the effect of different concentrations of glycerol on water retention in Example 3 of the present invention;

[0039] Figure 6 Graph comparing the swelling rates of the coatings in Example 4 and Comparative Example 3 of the present invention;

[0040] Figure 7 Graph comparing the monomer residue amounts of the coatings in Example 4 and Comparative Example 3 of the present invention;

[0041] Figure 8 Photograph of the hydrogel coating at 25°C in Example 5 of the present invention;

[0042] Figure 9 Photograph of the hydrogel coating at 45°C in Example 5 of the present invention;

[0043] Figure 10 Graph comparing the coating peeling area rates obtained in Example 6 and Comparative Example 4 of the present invention. Detailed implementation manners

[0044] The present invention will be further described below in conjunction with the embodiments. The following embodiments are narrative and not restrictive, and the protection scope of the present invention cannot be limited by the following embodiments.

[0045] All kinds of experimental operations involved in the specific embodiments are conventional techniques in the art. For the parts not specifically annotated in this article, those of ordinary skill in the art can refer to various commonly used reference books, scientific and technological literatures or relevant specifications, manuals, etc. before the filing date of the present invention application for implementation.

[0046] A hydrogel coating method, the method comprising the following steps:

[0047] (1) Using a high-voltage electrostatic spray gun, spraying hydrogel coating powder on the surface of the substrate material;

[0048] (2) Spraying a solution on the surface of the substrate material to redissolve the hydrogel coating powder and form a hydrogel coating.

[0049] Preferably, the preparation method of the hydrogel coating powder in step (1) is as follows:

[0050] S1. Prepare a viscous hydrogel and perform pretreatment;

[0051] S2. Grind it into powder, freeze-dry, sieve, and perform vacuum plasma treatment for 5 - 15 min;

[0052] S3. Mix with functional powder to obtain.

[0053] Preferably, the viscous hydrogel in step S1 has self-healing properties and includes one or more of dynamic covalent bonds such as Schiff base rebonding, hydrazide rebonding, oxime rebonding, borate ester, phenylborate ester, and silanol condensation.

[0054] Preferably, the viscous hydrogel is copolymerized from chitosan, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, acrylic acid, α-ketoglutaric acid, and 3-methacryloxypropyltrimethoxysilane.

[0055] Preferably, the ratio of chitosan, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, acrylic acid, α-ketoglutaric acid, and 3-methacryloxypropyltrimethoxysilane is g:g:g:mL:mL:μL = 0.56:0.28:0.12:20 - 40:5.6:20. Dissolve various viscous hydrogels in distilled water, and the ratio of chitosan to distilled water is g:mL = 0.56:100. Cure with ultraviolet light for 60 min to prepare the viscous hydrogel.

[0056] Preferably, step S1 also includes hydrogel pretreatment, including soaking in a working environment solution, and the working environment solution includes distilled water, physiological saline, digestive fluid, and seawater.

[0057] Preferably, the functional powder in step S3 includes thermosensitive hydrogel dry powder, SiO2, nano magnetic particles, and medicinal powder;

[0058] Preferably, the substrate material in step (2) includes various substrates such as metal, ceramic, wood, silica gel, glass, and skin;

[0059] Alternatively, the solution in step (2) includes various functional solutions such as salt solution, indicator solution, and organic water mixed solution.

[0060] A hydrogel coating prepared by the method described above.

[0061] The application of the method described above in surface processing and coating.

[0062] Specifically, the relevant preparation and detection are as follows:

[0063] Example 1

[0064] Use the coating method of the present invention to prepare a hydrogel coating on a 6 cm cube stainless steel target.

[0065] Preparation of hydrogel coating powder: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 40 mL of acrylic acid, 5.6 mL of 0.1 M α-ketoglutaric acid, and 20 μL of 3-methacryloxypropyltrimethoxysilane, dissolve them in 100 mL of distilled water, and carry out ultraviolet curing for 60 min to obtain a viscous hydrogel (the same applies to the following comparative examples). Freeze-dry, grind into powder, and pass through a 200-mesh sieve to obtain the hydrogel coating powder (i.e., viscous hydrogel dry powder, the same applies to the following comparative examples).

[0066] The specific steps of the hydrogel spraying method are as follows:

[0067] (1) Using a high-voltage electrostatic spray gun, spray the hydrogel coating powder onto the surface of a 6-cm cube stainless steel target;

[0068] (2) Spray water on the surface of the 6-cm cube stainless steel target to redissolve the hydrogel coating powder, and let it stand to wait for the formation of the hydrogel coating.

[0069] Freeze-dry the hydrogel coating, and use SEM electron microscopy to observe the surface morphology of the coating. The results are as Figure 1 shown, and a continuous and complete hydrogel coating can be formed on the stainless steel target.

[0070] Comparative Example 1

[0071] In Comparative Example 1, the hydrogel raw materials are the same as those in Example 1, and the difference lies in adopting the traditional coating steps:

[0072] Preparation of hydrogel coating: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 40 mL of acrylic acid, 5.6 mL of 0.1 M α-ketoglutaric acid, and 20 μL of 3-methacryloxypropyltrimethoxysilane, dissolve them in 100 mL of distilled water to prepare a hydrogel prepolymer solution;

[0073] The specific coating steps are as follows:

[0074] (1) In a glove box providing an inert gas environment, brush the hydrogel prepolymer solution onto a 6-cm cube stainless steel target;

[0075] (2) In a glove box providing an inert gas environment, carry out ultraviolet curing on the hydrogel prepolymer solution on the target to obtain a hydrogel coating.

[0076] Record the time and equipment required for the coating process in Table 1. The preparation method of the present invention takes significantly less time than the traditional method, and no complex equipment such as an ultraviolet light machine and a glove box is required during the spraying process, making it more convenient to use.

[0077] Table 1 Time required for the formation of the hydrogel coating

[0078] Spraying method Traditional method Coating time 11.5 ± 0.5 min 59.0 ± 4.4 min Coating equipment Electrostatic spray gun Glove box, ultraviolet lamp

[0079] The coating thickness at each corner, point center, and midpoint of the face (except the bottom face) of the cube was measured by the microscopic method. The coating was cut off, embedded in resin, and observed and measured under a microscope. The data are as Figure 2 shown. It can be seen that due to the flow of the prepolymer solution in the traditional method, it is not easy to coat at the edges and corners. The coating thickness at the edge is 41.3 ± 4.0 μm, and the coating thickness at the corner is 33 ± 2.1 μm, which is significantly lower than the coating thickness of 63 ± 5.1 μm on the face. For the coating prepared by the method of the present invention, the coating thicknesses at the face, edge, and corner are 62.6 ± 4.0 μm, 66.0 ± 5.6 μm, and 67.3 ± 6.8 μm, respectively, with no significant difference. This shows that the coating prepared by the method of the present invention has a higher uniformity.

[0080] Comparative Example 2

[0081] In Comparative Example 2, the coating raw materials were the same as those in Example 1, except that an ordinary spray gun was used for spraying instead of an electrostatic spray gun during the spraying process.

[0082] Preparation of hydrogel coating powder: 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 40 mL of acrylic acid, 5.6 mL of 0.1 M α-ketoglutaric acid, and 20 μL of 3-methacryloxypropyltrimethoxysilane were dissolved in 100 mL of distilled water and cured by ultraviolet light for 60 min to obtain a viscous hydrogel (the same for the following comparative examples). It was freeze-dried, ground into powder, and passed through a 200-mesh sieve to obtain the hydrogel coating powder (i.e., the viscous hydrogel dry powder, the same for the following comparative examples).

[0083] The specific steps of the hydrogel spraying method are as follows:

[0084] (1) Using a powder spray gun, the hydrogel coating powder was sprayed onto the surface of a 6-cm cube stainless steel target;

[0085] (2) Water was sprayed onto the surface of the 6-cm cube stainless steel target to redissolve the hydrogel coating powder, and it was left standing to wait for the formation of the hydrogel coating.

[0086] A universal testing machine was used to conduct a peeling test on the coating by the 90° peeling method. The film was peeled at a speed of 20 mm / min, and the force-displacement curve during the peeling process was recorded. The results are as Figure 3 shown. For the hydrogel coating prepared by the ordinary powder spraying method in Comparative Example 2, the film tearing force was unstable, while for the hydrogel coating prepared by the electrostatic powder spraying method in Example 1, the film tearing force was stable within a certain range, indicating that the use of the electrostatic spraying method is helpful for forming a uniform hydrogel coating.

[0087] Example 2

[0088] Prepare the hydrogel coating on a 6-cm cube stainless steel target by using the coating method described in the present invention.

[0089] Prepare the hydrogel coating powder: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 40 mL of acrylic acid, 5.6 mL of 0.1 M α-ketoglutaric acid, and 20 μL of 3-methacryloxypropyltrimethoxysilane and dissolve them in 100 mL of distilled water. Carry out ultraviolet curing for 60 min to obtain a viscous hydrogel (the same as in the comparative example below). Freeze-dry, grind into powder, pass through a 200-mesh sieve, and carry out vacuum plasma treatment for 10 min to obtain the hydrogel coating powder (i.e., viscous hydrogel dry powder, the same as in the comparative example below).

[0090] The specific steps of the hydrogel spraying method are as follows:

[0091] (1) Use a high-voltage electrostatic spray gun to spray the hydrogel coating powder on the surface of a 6-cm cube stainless steel target;

[0092] (2) Spray water on the surface of the 6-cm cube stainless steel target to redissolve the hydrogel coating powder, and let it stand to wait for the formation of the hydrogel coating.

[0093] Record the total weight of the powder used m t , the weight of the powder on the substrate surface m s , and calculate the powder deposition rate.

[0094] The powder deposition rate = m s / m t × 100%

[0095] The results are as Figure 4 shown. Compared with Example 1, vacuum plasma treatment increases the powder deposition rate from 87.4% ± 2.6% to 97.6% ± 2.1%, effectively enhancing the electrostatic spraying utilization rate of the powder.

[0096] Example 3

[0097] Prepare the hydrogel coating on a 6-cm cube stainless steel target by using the coating method described in the present invention.

[0098] Preparation of hydrogel coating powder: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 40 mL of acrylic acid, 5.6 mL of 0.1 M α-ketoglutaric acid, and 20 μL of 3-methacryloxypropyltrimethoxysilane, dissolve them in 100 mL of distilled water, and cure under ultraviolet light for 60 min to obtain a viscous hydrogel (the same applies to the following comparative examples). Freeze-dry, grind into powder, pass through a 200-mesh sieve, and perform vacuum plasma treatment for 10 min to obtain the hydrogel coating powder (i.e., viscous hydrogel dry powder, the same applies to the following comparative examples).

[0099] The specific steps of the hydrogel spraying method are as follows:

[0100] (1) Use a high-voltage electrostatic spray gun to spray the hydrogel coating powder on the surface of a 6-cm cube stainless steel target;

[0101] (2) Spray glycerol solutions with different concentrations on the surface of the 6-cm cube stainless steel target to redissolve the hydrogel coating powder, and let it stand to wait for the formation of the hydrogel coating.

[0102] Place the prepared sample in an environment of 25°C and 60% RH, measure the initial weight m1 of the hydrogel coating, measure the coating weight m2 after 3 days, and calculate the weight loss rate according to the following formula:

[0103] Weight loss rate = (m1 - m2) / m1 × 100%

[0104] The results are as Figure 5 shown. By changing the redissolving solution to a glycerol solution, the coating can be given moisture retention performance. For the hydrogel coating redissolved with pure water, the weight loss rate is nearly 100% after three days. Redissolving with glycerol solutions of different concentrations can significantly reduce the weight loss rate. It can be seen that the hydrogel coating can be given functionality by changing the redissolving solution, indicating that the coating method is flexible and has a wide range of applications.

[0105] At the same time, by comparing Example 1, Example 2, and Example 3, it can be seen that there is a synergistic effect between the two steps of vacuum plasma treatment and glycerol solution spraying in the method of the present invention, which can synergistically improve the relevant performance of the finally prepared hydrogel coating.

[0106] Example 4

[0107] Prepare a hydrogel coating for a medical forceps using the preparation method described in the present invention. The steps include:

[0108] Preparation of hydrogel coating powder: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 20 mL of acrylic acid, and 5.6 mL of 0.1 M α-ketoglutaric acid, dissolve them in 100 mL of distilled water, and perform ultraviolet curing for 60 min. Let it stand in physiological saline for 3 days, change the physiological saline every 24 h to pre-swell the coating, then freeze-dry, grind it into powder, pass through a 200-mesh sieve, and perform vacuum plasma treatment for 10 min to obtain the hydrogel coating powder.

[0109] The specific steps of the hydrogel spraying method are as follows:

[0110] (1) Use a high-voltage electrostatic spray gun to spray the coating powder on the surface of the medical forceps.

[0111] (2) Spray water on the surface of the medical forceps to re-dissolve the hydrogel coating powder and wait for the formation of the hydrogel coating.

[0112] Use the preparation method described in the present invention and the traditional method to prepare the hydrogel coating of the medical forceps with the same materials.

[0113] Comparative Example 3

[0114] The traditional method for preparing the hydrogel coating of the medical forceps includes the following steps:

[0115] Preparation of hydrogel coating: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 20 mL of acrylic acid, and 5.6 mL of 0.1 M α-ketoglutaric acid, dissolve them in 100 mL of distilled water to prepare a hydrogel prepolymer solution.

[0116] The specific steps of the traditional coating are as follows:

[0117] (1) In a glove box providing an inert gas environment, brush the hydrogel prepolymer solution on the medical forceps.

[0118] (2) In a glove box providing an inert gas environment, perform ultraviolet curing on the hydrogel prepolymer solution on the medical forceps to obtain the hydrogel coating.

[0119] Use a thickness gauge to measure the initial coating thickness l1 of the forceps prepared by the two methods. Immerse the forceps in plasma for 10 min and measure the coating thickness l2. Calculate the coating swelling rate according to the following formula:

[0120] Swelling rate = (l2 - l1) / l1 × 100%

[0121] The results are as Figure 6As shown, the swelling rate of the coating prepared by the traditional method used in Comparative Example 3 was 68.14% ± 10.05%, and the swelling rate of the coating prepared by the preparation method of the present invention in Example 4 was 7.48% ± 1.27%. It can be seen that the method of the present invention can effectively control the swelling rate of the coating in a special solution and reduce the coating deformation.

[0122] The liquid phase method was used to determine the monomer residue in the coating. An Agilent 1100 liquid phase instrument, an Elite Supersil AQ-C18 chromatographic column were used, the column temperature was 35 °C, the mobile phase A:B = 95:5, A was 0.5% diammonium hydrogen phosphate - phosphoric acid (pH 2.5), B was acetonitrile, and the flow rate was 1 ml / min. The results are as Figure 7 , the acrylic acid content of the coating prepared by the traditional method used in Comparative Example 3 was 17.57 ± 1.8 mg / g, and the acrylic acid content of the coating prepared by the preparation method of the present invention in Example 4 was 0.18 ± 0.01 mg / g. It can be seen that the method can effectively reduce the harmful monomer residue in the coating and reduce the toxicity of the coating.

[0123] Example 5

[0124] The hydrogel temperature-sensitive coating on a 6 cm * 6 cm circular glass target was prepared by the preparation method of the present invention.

[0125] Preparation of hydrogel coating powder: Viscous hydrogel dry powder and poly(N-isopropylacrylamide) dry powder were prepared and mixed in a mass ratio of 1:1 to obtain hydrogel coating powder;

[0126] The specific steps of the hydrogel spraying method are as follows:

[0127] (1) The coating powder was sprayed on the surface of a 6 cm * 6 cm circular glass target by a high-voltage electrostatic spray gun;

[0128] (2) Glycerol solutions with different concentrations were sprayed on the surface of the 6 cm * 6 cm circular glass target to redissolve the hydrogel coating powder and wait for the formation of a hydrogel temperature-sensitive coating.

[0129] The transparency changes of the coating at 25 °C and 45 °C were observed. The results are as Figure 8 , Figure 9 shown. The transparency of the hydrogel coating is different at different temperatures, and a temperature-sensitive hydrogel coating was successfully prepared. It can be seen that the coating method has flexibility and a wide application range. By doping functional powders, the hydrogel coating can be given functionality.

[0130] Example 6

[0131] Using the preparation method of the present invention, hydrogel coatings were prepared on the surfaces of different substrates (stainless steel, wood, glass, ceramic) with sizes of 1.5 cm * 6 cm.

[0132] Preparation of hydrogel coating powder: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 20 mL of acrylic acid, and 5.6 mL of 0.1 M α-ketoglutaric acid, dissolve them in 100 mL of distilled water, and cure under ultraviolet light for 60 min. Freeze-dry, grind into powder, and pass through a 200-mesh sieve to obtain the hydrogel coating powder.

[0133] The specific steps of the hydrogel spraying method are as follows:

[0134] (1) During the spraying process: Place a 0.5 cm * 5 cm acrylic film strip on the surface of the substrate, and use a high-voltage electrostatic spray gun to spray the coating powder on the surface of the tweezers on the surfaces of different substrates (stainless steel, wood, glass, ceramic).

[0135] (2) Spray water on the surfaces of different substrates (stainless steel, wood, glass, ceramic) to redissolve the hydrogel coating powder and wait for the formation of a hydrogel coating.

[0136] Comparative Example 4

[0137] In Comparative Example 4, the same hydrogel raw materials as in Example 6 were used, except that the traditional coating steps were adopted:

[0138] Preparation of hydrogel coating: Take 0.56 g of chitosan, 0.28 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide, 0.12 g of N-hydroxysuccinimide, 20 mL of acrylic acid, and 5.6 mL of 0.1 M α-ketoglutaric acid, dissolve them in 100 mL of distilled water to prepare a hydrogel prepolymer solution;

[0139] The specific steps of the traditional coating are as follows:

[0140] (1) In a glove box providing an inert gas environment, place a 0.5 cm * 5 cm acrylic film strip on the surface of the substrate, and brush the hydrogel prepolymer solution on the surfaces of different substrates (stainless steel, wood, glass, ceramic).

[0141] (2) In a glove box providing an inert gas environment, cure the hydrogel prepolymer solution on the surfaces of different substrates (stainless steel, wood, glass, ceramic) under ultraviolet light to obtain a hydrogel coating.

[0142] Use a universal testing machine to conduct a peeling test on the coating by the 90° peeling method, peel the film at a speed of 20 mm / min, and record the peeling area of the coating. Calculate the peeling area rate using the following formula:

[0143] Peeling area rate = peeling area / total coating area × 100%

[0144] The results are as Figure 10, the peeling area rate of the coating prepared by the traditional method is significantly higher than that of this preparation method during the peeling process. For example, the peeling area rate of the method on a stainless steel target can reach 13 ± 3.6%, while this preparation method is only 3.3 ± 1.5%. This shows that the hydrogel coating prepared by this preparation method has stronger adhesion, is not easy to fall off, and is applicable to a variety of substrates.

[0145] Although embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that: without departing from the spirit and scope of the present invention and the appended claims, various substitutions, changes, and modifications are possible. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments.

Claims

1. A hydrogel coating method, characterized in that: The method includes the following steps: (1) Using a high-voltage electrostatic spray gun, spraying the hydrogel coating powder on the surface of the substrate material; (2) Spraying a solution on the surface of the substrate material to redissolve the hydrogel coating powder and form a hydrogel coating; The preparation method of the hydrogel coating powder in step (1) is as follows: S1. Prepare a viscous hydrogel and perform pretreatment; S2. Grind it into powder, freeze-dry, sieve, and perform vacuum plasma treatment for 5 - 15 min; S3. Mix it with functional powder to obtain the product; In step S1, the viscous hydrogel has self-healing properties and includes one or more of Schiff base rebonding, hydrazide rebonding, oxime rebonding, borate ester, phenylborate ester, and silanol condensation dynamic covalent bonds; The viscous hydrogel is copolymerized from chitosan, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, acrylic acid, α-ketoglutaric acid, and 3-methacryloxypropyltrimethoxysilane; In step S1, hydrogel pretreatment is also included, which includes soaking in a working environment solution, and the working environment solution includes distilled water, physiological saline, digestive tract fluid, and seawater.

2. The preparation method according to claim 1, characterized in that: The ratio of chitosan, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, acrylic acid, α-ketoglutaric acid, and 3-methacryloxypropyltrimethoxysilane is g:g:g:mL:mL:μL as 0.56:0.28:0.12:20 - 40:5.6:

20. Dissolve various viscous hydrogels in distilled water, and the ratio of chitosan:distilled water is g:mL as 0.56:100, and perform ultraviolet curing for 60 min to prepare the viscous hydrogel.

3. The preparation method according to claim 1, characterized in that: In step S3, the functional powder includes thermosensitive hydrogel dry powder, SiO2, nano magnetic particles, and medicinal powder.

4. The hydrogel coating method according to claim 1, wherein: In step (2), the substrate material includes metal, ceramic, wood, silica gel, glass, or skin; Alternatively, in step (2), the solution includes a salt solution, an indicator solution, or an organic water mixed solution.

5. A hydrogel coating prepared by using the method according to any one of claims 1 to 4.

6. The application of the method according to any one of claims 1 to 4 in surface processing and coating.

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