High skin adhesion, ultra-thin self-heating sheet and preparation method thereof

Abstract

The application provides a high-skin-adhesion, ultra-thin self-heating sheet and a preparation method thereof. A precursor solution is prepared by mixing a suspending agent with water, dissolving at high temperature, adding a metal salt after cooling, stirring uniformly, adding a heating powder, and stirring at room temperature until a high suspension state is obtained. A support solution is prepared by dissolving an elastic polymer and a lignocellulose in a polar organic solvent, stirring and dissolving at high temperature, and obtaining the support solution. The precursor solution is placed in a pressure injector, and the support solution is placed in an electrostatic spinning device. The two solutions are sprayed to a collecting device at the same time from the same plane to obtain a sponge-like heating body film. The sponge-like heating body film is vacuum dried to obtain the high-skin-adhesion, ultra-thin self-heating sheet. The self-heating sheet has the advantages of simple structure, ultra-thin, easy-to-implement preparation process, high softness, high skin adhesion, and uniform heating, and can be widely applied to the fields of portable heating, medical care, and other related fields of people's livelihood and military.

Description

Technical Field

[0001] This invention relates to the field of self-heating materials technology, and in particular to a highly skin-adhesive, ultra-thin self-heating sheet and its preparation method. Background Technology

[0002] As humanity's exploration of nature continues and its activity space expands, combating low temperatures has become a major challenge. Traditional passive heating is unsuitable for extremely cold environments and for those engaged in delicate work. This problem has driven the development of active heating methods, also known as passive body heating, which convert external energy into heat to assist in body warming. Clinical studies have shown that appropriately introducing heat from outside the body can promote sleep and alleviate and treat conditions such as temperature-sensitive diseases and chronic pain. Chemical heating agents, primarily made from iron powder, utilize the electrochemical corrosion of iron to generate heat. They offer advantages such as high energy density, easy triggering, rapid heating, and low cost. They are widely used in portable heating and healthcare applications closely related to people's livelihoods and the military, and are particularly suitable for situations requiring high mobility, limited resources, and urgent needs, such as field rescue and outdoor activities.

[0003] Currently, self-heating products generally exist in the form of powdered heating elements or thin sheet heating elements. An invention patent (publication number CN 1596850A) discloses a self-heating foot warmer, comprising a heat-releasing material, an inner bag, and an outer bag. The heat-releasing material, by weight percentage, includes: 25-85% iron powder, 1-12% inorganic salts, 3-50% activated carbon, 0-40% water, and 0-10% wood powder. The heat-releasing material is placed inside the inner bag, which is placed inside the outer bag made of plastic material. The inner bag material is a slightly breathable non-woven composite film. However, this self-heating foot warmer is a bagged powder, which cannot be shaped. In practical applications, uneven thickness can easily lead to uneven heating. Furthermore, since the heating element is powder, if the powder leaks and comes into direct contact with skin or clothing, or even be ingested, there is a risk of burns, contamination, and poisoning.

[0004] In addition, existing thin-film heating elements have problems such as poor skin adhesion, easy formation of hard lumps over time, and poor flexibility due to their thickness, making them unsuitable for use in wearable products.

[0005] In view of this, it is necessary to design an improved, highly skin-adhesive, ultra-thin self-heating pad and its preparation method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a highly skin-friendly, ultra-thin self-heating sheet and its preparation method. By selecting a suspending agent with high suspension performance and combining it with the preparation process, the dispersion uniformity of the heating powder in the sponge support is improved, resulting in an ultra-thin self-heating sheet with simple structure, high elasticity, high softness, high skin-friendliness and uniform heating.

[0007] To achieve the above-mentioned objectives, this invention provides a method for preparing a highly skin-adhesive, ultra-thin self-heating pad, comprising the following steps:

[0008] S1. Preparation of precursor solution: The suspending agent powder is mixed with water, dissolved at high temperature, cooled to a preset temperature, and then a metal salt is added and stirred evenly. Finally, the heating powder is added and stirred at room temperature until a high suspension state is reached to obtain the precursor solution; the suspending agent powder is gellan gum powder.

[0009] S2. Preparation of the support solution: The elastic polymer and lignocellulose are dissolved in a polar organic solvent and stirred at high temperature to obtain the support solution.

[0010] S3. Place the precursor solution from step S1 into a pressure injector, and place the support solution from step S2 into an electrospinning device. The injection tip of the pressure injector and the spinneret of the electrospinning device are on the same plane. At the same time, spray the solution onto the collection device for a preset time to obtain a sponge-like heating element film.

[0011] S4. Place the sponge-like heating element film obtained in step S3 under vacuum drying at 140-160℃ for 22-26 hours to obtain a highly skin-friendly, ultra-thin self-heating sheet.

[0012] As a further improvement of the present invention, in step S1, the mass ratio of the suspending agent to the metal salt in the precursor solution is (0.1-3):(20-50), and the mass ratio of the suspending agent to the heating powder is 1:(40-240); the mass percentage of all solutes in the precursor solution is 21%-47%.

[0013] As a further improvement of the present invention, in step S1, the high temperature for dissolving the suspending agent powder is 70-90°C, the preset temperature is 35-45°C, and the metal salt is one of sodium chloride, potassium chloride, and magnesium chloride halide.

[0014] As a further improvement of the present invention, in step S2, the mass percentage concentration of the solute in the support solution is 8% to 20%; the mass percentage of the elastic polymer to the lignocellulose is (30% to 80%):(70% to 20%), and the elastic polymer includes one of polyurethane, polyvinylidene fluoride, and polyacrylonitrile.

[0015] As a further improvement of the present invention, in step S3, the distance between the collecting device and the plane where the injection tip and the spinneret are located is 8 to 30 cm.

[0016] As a further improvement of the present invention, the pressure of the pressure injector is 20-30 kPa, the voltage of the electrospinning device is 8-25 kV, the propulsion speed is 0.1-2 mL / h, and the preset spraying time is 2-10 h.

[0017] As a further improvement of the present invention, in step S1, the precursor solution further includes a solution A with a mass percentage of 14% to 21%, wherein the solute of solution A includes wood pulp and superabsorbent resin in a mass ratio of (5 to 10):(1.5 to 5), and the solvent is water.

[0018] As a further improvement of the present invention, the heating powder comprises, by weight percentage: 40% to 90% iron powder, 7% to 10% activated carbon and 1% to 20% vermiculite.

[0019] As a further improvement of the present invention, in step S2, the polar organic solvent includes one of dimethylformamide, dimethylacetamide, and dimethyl sulfoxide; the temperature for stirring and dissolving is 50-60°C.

[0020] A highly skin-friendly, ultra-thin self-heating sheet prepared by any one of the above methods, the highly skin-friendly, ultra-thin self-heating sheet comprising a sponge-like support and a heating element composited within the sponge-like support; the thickness of the highly skin-friendly, ultra-thin self-heating sheet is 0.5–1.5 mm.

[0021] The beneficial effects of this invention are:

[0022] 1. In the highly skin-friendly, ultra-thin self-heating sheet and its preparation method of the present invention, the precursor solution is prepared by dissolving a suspending agent with high suspension performance in water, adding a metal salt and stirring evenly. Under the action of the metal salt, the suspending agent forms a network cross-linked structure in the solution, exhibiting a gel-like state. Finally, the heating powder is added. Under the action of the highly suspension-performance suspending agent, the heating powder is uniformly and stably distributed in a suspended state in the precursor, which is beneficial for the uniform loading of the heating powder in the support during subsequent spraying, forming a uniformly heated self-heating sheet. In addition, the present invention uses an elastic polymer and lignocellulose as support materials. The elastic polymer improves the elasticity and extensibility of the self-heating sheet, which is beneficial for preparing a soft, highly skin-friendly self-heating sheet; lignocellulose acts as a water conductor, which is beneficial for the dispersion of water in the self-heating sheet and promotes the uniformity of heating. Thus, the self-heating sheet has the advantages of simple structure, easy preparation process, high elasticity, high softness, high skin-friendliness and uniform heating, and has a wide range of applications.

[0023] 2. In the preparation process of the self-heating sheet of this invention, the precursor solution is placed in a pressure injector, and the support solution is placed in an electrospinning device, and both are sprayed onto the collection device simultaneously from the same plane. This not only allows for flexible control of the thickness of the self-heating sheet, resulting in an ultra-thin self-heating sheet, but also facilitates the uniform loading of the heating powder in the precursor solution into the spatial structure of the sponge support, avoiding the problem of uneven heating caused by the deposition of heating material. Furthermore, the pressure injection method imparts a certain impact force to the heating material, which is more conducive to its firm bonding with the sponge support, improving the bonding force between the support and the heating powder, thereby improving the practical performance of the self-heating sheet.

[0024] 3. The highly skin-friendly, ultra-thin self-heating sheet of the present invention can be used as a heating element for wearable products and can be widely used in portable heating and medical care and other fields closely related to people's livelihood and military affairs. It is especially suitable for situations with high mobility, limited conditions and urgent needs, such as field rescue and outdoor activities. Attached Figure Description

[0025] Figure 1 This is a simplified schematic diagram of the preparation method of the highly skin-adhesive, ultra-thin self-heating sheet of the present invention.

[0026] Figure 2 This is a schematic diagram of the internal structure of the highly skin-adhesive, ultra-thin self-heating sheet of the present invention.

[0027] Figure Labels

[0028] 100 - Pressure injector; 110 - Injection tip; 200 - Electrospinning device; 210 - Spinneret; 300 - Collection device. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0031] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] Please see Figure 1As shown, a method for preparing a highly skin-adhesive, ultra-thin self-heating pad includes the following steps:

[0033] S1. Preparation of precursor solution: Mix suspending agent powder with water, dissolve at high temperature, cool to the preset temperature, add metal salt and stir evenly, finally add heating powder and stir at room temperature until highly suspended to obtain precursor solution; suspending agent powder is gellan gum powder.

[0034] After dissolving a suspending agent with high suspension performance in water, metal salts are added and stirred evenly. Under the action of the metal salts, the suspending agent forms a network cross-linked structure in the solution, exhibiting a gel-like state. Finally, heating powder is added. Under the action of the suspending agent with high suspension performance, the heating powder is uniformly and stably distributed in the precursor in a suspended state, which is beneficial for the heating powder to be uniformly loaded in the support during the subsequent spraying process, forming a self-heating sheet with uniform heating.

[0035] S2. Preparation of support solution: Dissolve the elastic polymer and lignocellulose in a polar organic solvent and stir at high temperature to obtain the support solution;

[0036] Elastic polymers and lignocellulose were selected as support materials. The elastic polymers improved the elasticity and extensibility of the self-heating sheet, which is beneficial for preparing a soft and highly skin-friendly self-heating sheet. Because a certain amount of water needs to be injected into the highly skin-friendly and ultra-thin self-heating sheet in advance, the heating rate will be accelerated after contact with air during subsequent application. The lignocellulose plays a water-conducting role, which is conducive to the dispersion of water in the self-heating sheet and promotes the uniformity of heating.

[0037] S3. Place the precursor solution from step S1 into the pressure injector 100, and place the support solution from step S2 into the electrospinning device 200. The injection tip 110 of the pressure injector 100 and the spinneret 210 of the electrospinning device 200 are located on the same plane. At the same time, spray the solution onto the collection device 300 for a preset time to obtain a sponge-like heating element film.

[0038] This process not only allows for flexible control of the thickness of the self-heating sheet, resulting in an ultra-thin self-heating sheet, but also facilitates the uniform loading of the heating powder in the precursor solution onto the spatial structure of the sponge support, avoiding uneven heating caused by the deposition of heating materials. Furthermore, the pressure injection method imparts a certain impact force to the heating material, which is more conducive to its firm bonding with the sponge support, improving the bonding force between the support and the heating powder, thereby enhancing the practical performance of the self-heating sheet.

[0039] S4. Place the sponge-like heating element film obtained in step S3 under vacuum drying at 140-160℃ for 22-26 hours to obtain a highly skin-friendly, ultra-thin self-heating sheet.

[0040] Specifically, in step S1, the mass ratio of suspending agent to metal salt in the precursor solution is (0.1–3):(20–50), and the mass ratio of suspending agent to heating powder is 1:(40–240); the mass percentage of all solutes in the precursor solution is 21%–47%. The high temperature for dissolving the suspending agent powder is 70–90°C, with a preset temperature of 35–45°C. The metal salt is one of the halide salts such as sodium chloride, potassium chloride, and magnesium chloride. The heating powder, by weight percentage, comprises: 40%–90% iron powder, 7%–10% activated carbon, and 1%–20% vermiculite.

[0041] In step S2, the mass percentage concentration of the solute in the support solution is 8%–20%; the mass percentage of the elastic polymer to lignocellulose is (30%–80%):(70%–20%), and the elastic polymer includes one of polyurethane (PU), polyvinylidene fluoride (PVDF), and polyacrylonitrile (PAN). The polar organic solvent includes one of dimethylformamide, dimethylacetamide, and dimethyl sulfoxide; the stirring and dissolving temperature is 50–60°C.

[0042] In step S3, the distance between the collecting device and the plane containing the injection tip and the spinneret is 8–30 cm. The pressure of the pressure injector is 20–30 kPa, the voltage of the electrospinning device is 8–25 kV, and the propulsion speed is 0.1–2 mL / h; the preset spraying time is 2–10 h.

[0043] In some other embodiments, in step S1, the precursor solution further includes a solution A with a mass percentage of 14% to 21%, wherein the solute of solution A includes wood pulp and superabsorbent resin in a mass ratio of (5 to 10):(1.5 to 5), and the solvent is water.

[0044] A highly skin-friendly, ultra-thin self-heating pad includes a sponge-like support body and a heating element composited within the sponge-like support body; the thickness of the highly skin-friendly, ultra-thin self-heating pad is 0.5–1.5 mm. This self-heating pad has the advantages of simple structure, easy manufacturing process, high elasticity, high softness, high skin-fittingness, and uniform heating, and has a wide range of applications. This self-heating pad can be used as a heating element in wearable products and can be widely applied in portable heating and healthcare fields closely related to people's livelihoods and the military, especially suitable for situations with high mobility, limited conditions, and urgent needs, such as field rescue and outdoor activities.

[0045] In practical applications, the highly skin-friendly, ultra-thin self-heating sheet of the present invention needs to be covered with breathable membranes on both sides to control the heating rate. Other functional membrane layers can also be combined according to the actual application scenario.

[0046] Example 1

[0047] Please see Figure 1As shown, this embodiment provides a highly skin-adhesive, ultra-thin self-heating pad and its preparation method, including the following steps:

[0048] S1. Preparation of precursor solution: Add 0.25g of gellan gum powder to water to a weight of 60g and mix. Dissolve at 80℃, cool to 40℃ and add 13.3g of sodium chloride and stir evenly. Finally, add 40g of heating powder and stir at room temperature until it reaches a high suspension state to obtain the precursor solution. The heating powder contains 80% iron powder and 20% activated carbon.

[0049] S2. Preparation of the support solution: Dissolve PAN and lignocellulose in dimethylformamide and stir at 50°C to obtain the support solution; wherein the mass percentage of PAN and lignocellulose is 50%:50%;

[0050] S3. Place the precursor solution from step S1 into a pressure injector, and place the support solution from step S2 into an electrospinning device. The injection tip of the pressure injector and the spinneret of the electrospinning device are on the same plane. At the same time, spray the solution onto the collection device for a preset time to obtain a sponge-like heating element film.

[0051] The distance between the collecting device and the plane containing the injection tip and spinneret is 13 cm. The pressure of the pressure injector is 20 kPa, the voltage of the electrospinning device is 20 kV, the feed rate is 1 mL / h, and the preset spraying time is 6 h.

[0052] S4. Place the sponge-like heating element film obtained in step S3 under vacuum drying at 150°C for 24 hours to obtain a highly skin-friendly, ultra-thin self-heating sheet with a thickness of 1 mm.

[0053] Comparative Example 1

[0054] Comparative Example 1 provides a self-heating element and its preparation method. The difference from Example 1 is that gellan gum powder is not added in step S1. The rest is roughly the same as Example 1, and will not be repeated here.

[0055] Comparative Example 2

[0056] Comparative Example 2 provides a self-heating pad and its preparation method. The difference from Example 1 is that sodium chloride is not added in step S1. The rest is roughly the same as Example 1, and will not be repeated here.

[0057] Comparative Example 3

[0058] Comparative Example 3 provides a self-heating sheet and its preparation method. The difference from Example 1 is that lignocellulose is not added in step S2. The rest is roughly the same as Example 1 and will not be repeated here.

[0059] Comparative Example 4

[0060] Comparative Example 4 provides a self-heating sheet and its preparation method. Compared with Example 1, the difference is that in step S3, after the support solution is prepared into a film using an electrospinning device, the precursor solution from step S1 is directly coated onto the film surface. The rest is roughly the same as in Example 1, and will not be described again here.

[0061] Comparative Example 5

[0062] Comparative Example 5 provides a self-heating element and its preparation method. Compared with Example 1, the difference is that in step S3, the pressure injector and the electrospinning device are alternately sprayed in a cycle. The rest is roughly the same as Example 1, and will not be described again here.

[0063] Comparative Example 6

[0064] Comparative Example 6 provides a self-heating sheet and its preparation method. Compared with Example 1, the difference is that in step S3, after mixing the precursor solution and the support solution, the self-heating sheet is directly prepared by electrospinning. The rest is roughly the same as Example 1, and will not be described again here.

[0065] Softness rating:

[0066] The softness of different samples was rated from level 1 to level 6, with softness increasing. The existing powdered heating packs of the same size were rated as level 1 in terms of softness.

[0067] The softness, elasticity, and heating performance of the self-heating sheets prepared in Example 1 and Comparative Examples 1-6 were tested, and the results are shown in the table below. The heating time is the time when the temperature of the self-heating sheet exceeds 40°C; if it does not exceed 40°C, the heating effect is not considered.

[0068] Table 1. Performance test results of the self-heating element in Example 1 and Comparative Examples 1-6

[0069] Example 1 Softness level 5 45 58.8 Comparative Example 1 Softness level 6 0 25.3 Comparative Example 2 Softness level 6 No fever 21.5 Comparative Example 3 Softness level 3 11 42.5 Comparative Example 4 Softness level 5 21 62.3 Comparative Example 5 Softness level 4 0 37.5 Comparative Example 6 Softness level 5 45 61.8

[0070] As shown in Table 1, in Comparative Example 1, the absence of gellan gum prevented the iron powder from being evenly dispersed in the precursor solution, resulting in the heating element barely generating heat. In Comparative Example 2, the absence of sodium chloride meant there was no electrolyte solution in the reaction, preventing the redox reaction and the exothermic reaction, thus the heating element did not generate heat. In Comparative Example 3, the absence of lignocellulose resulted in little change in heating efficiency compared to the examples, but the softness of the self-heating element decreased. In Comparative Example 4, after the support solution was prepared into a film using an electrospinning device in step S3, the precursor solution from step S1 was directly coated onto the film surface. Due to the concentrated and high-purity heating powder, the reaction was fast and the heating temperature was high, but the bonding force between the heating powder and the support was poor, leading to easy powder shedding and poor applicability of the heating element. In Comparative Example 5, when the pressure injector and the electrospinning device were used for alternating spraying in step S3, the heating powder was unevenly dispersed, resulting in poor heating efficiency. Furthermore, due to the presence of a separate heating layer, the softness was not as good as in Example 1. In Comparative Example 6, the precursor solution and support solution were mixed, and self-heating sheets were directly prepared using an electrospinning device. Due to poor mixing uniformity, the heating was uneven, with the highest heating point reaching 61.8℃, which reduced comfort during use. Regarding softness, if the suspension effect of the precursor solution is poor, heating sheets with gradually decreasing softness will appear during mass production. This is because when the suspension performance is poor, the heating sheets initially obtained from spraying contain only lighter components such as activated carbon, resulting in high softness. However, in the final product, the heavier portion of the heating powder is sprayed out, forming the heating sheet with low softness, which is detrimental to product performance stability and quality assurance.

[0071] Examples 2-7 and Comparative Examples 7-8

[0072] Examples 2-7 and Comparative Examples 7-8 respectively provide a self-heating sheet and its preparation method. Compared with Example 1, the difference is that in step S1, the amount of gellan gum powder, sodium chloride and heating powder added is different, as shown in Table 2. The rest is roughly the same as in Example 1, and will not be repeated here.

[0073] Table 2 shows the parameter settings for Examples 2-7 and Comparative Examples 7-8.

[0074] Example 2 2 13.3 40 Example 3 5 13.3 40 Example 4 0.25 10 40 Example 5 0.25 15 40 Example 6 0.25 13.3 32.5 Example 7 0.25 13.3 45 Comparative Example 7 0.1 13.3 40 Comparative Example 8 0.25 5 40

[0075] The self-heating sheets prepared in Examples 2-7 and Comparative Examples 7-8 were tested for softness, stretchability, and heating performance. The results are shown in the table below.

[0076] Table 3. Performance test results of the self-heating elements in Examples 2-7 and Comparative Examples 7-8

[0077] Example 2 Softness level 5 53 61.2 Example 3 Softness level 5 53 59.3 Example 4 Softness level 4 13 51.6 Example 5 Softness level 5 46 55.2 Example 6 Softness level 5 37 42 Example 7 Softness level 5 85 67.3 Comparative Example 7 Softness level 4 10 48.1 Comparative Example 8 Softness level 4 3 42.1

[0078] Table 3 shows that the effective concentration of gellan gum is 0.25g. After reaching this concentration, further increases in concentration do not affect its suspension effect on the heating powder. In Comparative Example 7, the amount of gellan gum added was relatively small, resulting in poor suspension. The iron powder could not be evenly dispersed in the precursor solution, leading to a decrease in the maximum temperature and heating time of the self-heating sheet. Furthermore, the initial heating effect of the sheet was poor, with a low temperature and a long heating time. Additionally, due to the poor suspension of the heating powder, it concentrated on the surface of the self-heating sheet in the later stages of preparation, reducing its softness. Correspondingly, sodium chloride, as an auxiliary suspending agent, also has an effective concentration. Low concentrations affect the suspension effect, as seen in Comparative Example 8, but increasing the concentration does not have a significant impact. The softness of the self-heating sheet is significantly affected by the concentration of the suspending agent. In actual mass production, only by reaching the effective concentration of the suspending agent can a precursor solution with high suspension of the heating powder be obtained, resulting in a heating sheet with uniform dispersion of various components after spraying, avoiding problems of uneven dispersion and poor softness.

[0079] In summary, this invention provides a highly skin-adhesive, ultra-thin self-heating sheet and its preparation method. By selecting a suspending agent with high suspension performance and combining it with the preparation process, the uniformity of the dispersion of the heating powder in the sponge support is improved. The high suspension performance, under the action of the metal salt, forms a network cross-linked structure in the solution, exhibiting a gel-like state. Under the action of the high suspension performance suspending agent, the heating powder is uniformly and suspended in the precursor, which is beneficial for the uniform loading of the heating powder in the support during subsequent spraying, forming a uniformly heating self-heating sheet. In the preparation process of the self-heating sheet, the pre-... The precursor solution is placed in a pressure injector, while the support solution is placed in an electrospinning device. Both solutions are simultaneously sprayed onto a collecting device from the same plane. This not only allows for flexible control of the self-heating sheet thickness, resulting in an ultra-thin self-heating sheet, but also facilitates the uniform loading of the heating powder in the precursor solution into the spatial structure of the sponge support, avoiding uneven heating caused by the deposition of heating materials. Furthermore, the pressure injection method imparts a certain impact force to the heating material, which is more conducive to its firm bonding with the sponge support, improving the adhesion between the support and the heating powder, thereby enhancing the practical performance of the self-heating sheet. The self-heating sheet of this invention features a simple structure, ultra-thinness, high elasticity, high softness, high skin-fittingness, and uniform heating. It can be used as a heating element for wearable products and can be widely applied in portable heating and healthcare fields closely related to people's livelihoods and the military. It is particularly suitable for situations with high mobility, limited conditions, and urgent needs, such as field rescue and outdoor activities.

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a highly skin-adhesive, ultra-thin self-heating pad, characterized in that, Includes the following steps: S1. Preparation of precursor solution: Gellan gum powder is mixed with water and dissolved at high temperature. After cooling to a preset temperature, metal salt is added and stirred evenly. The gellan gum powder forms a network cross-linked structure in the solution. Finally, heating powder is added and stirred at room temperature until it reaches a high suspension state to obtain the precursor solution. The precursor solution also includes solution A with a mass percentage of 14% to 21%. The solute of solution A includes wood pulp and superabsorbent resin in a mass ratio of (5 to 10): (1.5 to 5), and the solvent is water. The heating powder comprises 80% iron powder and 20% activated carbon by weight percentage. In the precursor solution, the mass ratio of gellan gum powder to metal salt is (0.1~3):(20~50), and the mass ratio of gellan gum powder to exothermic powder is 1:(40~240). S2. Preparation of the support solution: The elastic polymer and lignocellulose are dissolved in a polar organic solvent and stirred at high temperature to obtain the support solution. In the support solution, the mass percentage concentration of the solute is 8%~20%; the mass percentage of the elastic polymer to lignocellulose is (30%~80%):(70%~20%). S3. Place the precursor solution from step S1 into a pressure injector, and place the support solution from step S2 into an electrospinning device. The injection tip of the pressure injector and the spinneret of the electrospinning device are on the same plane. At the same time, spray the solution onto the collection device for a preset time to obtain a sponge-like heating element film. S4. The sponge-like heating element film obtained in step S3 is placed in a vacuum dryer at 140~160 ℃ for 22~26 h to obtain a highly skin-friendly, ultra-thin self-heating sheet; the highly skin-friendly, ultra-thin self-heating sheet relies on the electrochemical corrosion of iron powder with oxygen in the presence of an aqueous electrolyte to release heat.

2. The method for preparing the highly skin-adherent, ultra-thin self-heating sheet according to claim 1, characterized in that, In step S1, the high temperature for dissolving the gellan gum powder is 70~90℃, the preset temperature is 35~45℃, and the metal salt is one of sodium chloride, potassium chloride, and magnesium chloride.

3. The method for preparing the highly skin-adherent, ultra-thin self-heating sheet according to claim 1, characterized in that, In step S2, the elastic polymer includes one of polyurethane, polyvinylidene fluoride, and polyacrylonitrile.

4. The method for preparing the highly skin-adherent, ultra-thin self-heating sheet according to claim 1, characterized in that, In step S3, the distance between the collecting device and the plane where the injection tip and the spinneret are located is 8~30 cm.

5. The method for preparing the highly skin-adherent, ultra-thin self-heating sheet according to claim 4, characterized in that, The pressure of the pressure injector is 20~30 kPa, the voltage of the electrospinning device is 8~25 kV, the propulsion speed is 0.1~2 mL / h, and the preset spraying time is 2~10 h.

6. The method for preparing the highly skin-adherent, ultra-thin self-heating sheet according to claim 1, characterized in that, In step S2, the polar organic solvent includes one of dimethylformamide, dimethylacetamide, and dimethyl sulfoxide; the temperature for stirring and dissolving is 50~60℃.

7. A highly skin-adherent, ultra-thin self-heating sheet prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The highly skin-friendly, ultra-thin self-heating sheet includes a sponge-like support and a heating element composited inside the sponge-like support; the thickness of the highly skin-friendly, ultra-thin self-heating sheet is 0.5~1.5 mm.

Images