A long-lasting constant-temperature self-heating body and a method for manufacturing the same

Abstract

The application relates to the technical field of self-heating products, and provides a long-lasting constant-temperature self-heating body and a preparation method thereof, wherein the self-heating body comprises the following raw materials in proportion by weight: iron powder 40-60 parts, activated carbon 10-20 parts, modified polypropylene fiber 1-5 parts, water-absorbing material 1-3 parts, vermiculite 5-8 parts, binder 1-3 parts, salt 2-5 parts and deionized water 10-20 parts. The self-heating body provided by the application has the characteristics of constant-temperature and long-lasting heating.

Description

Technical Field

[0001] This invention relates to the field of self-heating product technology, and in particular to a long-lasting constant-temperature self-heating body and its preparation method. Background Technology

[0002] With the advancement of technology and the fast pace of life, people need to spend long periods of time facing computers or reading documents. Prolonged close-range use of the eyes can cause eye fatigue, leading to problems such as dry eyes, heavy eyelids, and eye socket pain. To address these issues, steam eye mask products have emerged on the market in recent years. The self-heating element is the key component in steam eye masks, which includes basic ingredients such as iron powder, activated carbon, vermiculite, resin, and salt. It utilizes the principle that oxygen in the air reacts with iron powder and activated carbon to form a heating element that releases water vapor and heat, thereby relieving eye fatigue, moisturizing, and enhancing blood circulation in the eyes.

[0003] Despite the numerous advantages mentioned above, the heating principle of steam eye masks is based on the chemical reaction between the heating element and oxygen in the air, which releases heat and achieves the purpose of heating. Because the heating element suddenly comes into contact with a large amount of oxygen after changing from an oxygen-free state, the reaction is relatively violent. As a result, most steam eye masks on the market currently have the problem of rapid heating in the early stage and rapid cooling in the later stage. Therefore, the development of steam eye masks is gradually moving towards the direction of being able to maintain the temperature for a longer time and a more constant temperature.

[0004] Patent CN 117379248 A discloses a method for preparing a thin and light self-heating sheet and its application. The self-heating sheet is composed of 30.0-50.0 parts of iron powder, 18.0-32.0 parts of activated carbon, 20.0-30.0 parts of salt water, and 5.0-12.0 parts of soft polymer hydrosol. The application obtains the thin and light self-heating sheet by spraying salt water onto the surface of a cut sheet, covering the surface of the sheet with a breathable and moisture-permeable membrane, and sealing the edges. The preparation method of this invention is simple and the self-heating sheet prepared is relatively uniform in heating, thin, has low hardness, and high tensile strength. However, this application does not address the problem of rapid early heating and rapid later cooling of steam eye masks.

[0005] Therefore, there is an urgent need in the market for a self-heating body that can generate heat at a constant and long-lasting temperature. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention selects iron powder, activated carbon, vermiculite and other substances as basic components, designs and adds modified polypropylene fiber, and combines it with water-absorbing materials, binders, salt and deionized water to make a self-heating body, which has the characteristics of being able to generate heat at a constant temperature and for a long time.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a long-lasting constant temperature self-heating body, which, by weight, comprises the following raw materials: 40-60 parts iron powder, 10-20 parts activated carbon, 1-5 parts modified polypropylene fiber, 1-3 parts water-absorbing material, 5-8 parts vermiculite, 1-3 parts binder, 2-5 parts salt, and 10-20 parts deionized water.

[0008] In some embodiments of the present invention, the iron powder has a particle size of 120-150 mesh.

[0009] The applicant selected iron powder with a particle size of 120-150 mesh, which has the characteristics of moderate heating rate, uniform heating and suitable continuous heating time.

[0010] In some embodiments of the present invention, the particle size of the activated carbon is 150-200 mesh.

[0011] The applicant selected activated carbon with a particle size of 150-200 mesh. Its high specific surface area allows it to quickly adsorb and store sufficient oxygen and moisture, enabling the iron powder oxidation reaction to start faster. Furthermore, the fine particles are easily dispersed evenly in the heating layer, reducing the risk of "hot spots".

[0012] In some embodiments of the present invention, the method for preparing the modified polypropylene fiber includes the following steps: (1) PP, EVOH and PP-g-MAH are dried separately, then mixed, extruded and granulated, and dried to obtain a mixed material for later use; (2) O-carboxymethyl chitosan was pulverized and dried to obtain microparticles for later use; (3) Add the microparticles from step (2) to the mixed material from step (1), blend and dry, extrude and granulate, melt and hollow spin at 190-200℃, cool to room temperature, and heat treat at 135-145℃ for 50-70 minutes to obtain modified polypropylene fiber.

[0013] In some embodiments of the present invention, in step (1), the mass ratio of PP to EVOH is 1:(0.05-0.15).

[0014] Preferably, in step (1), the mass ratio of PP to EVOH is 1:0.1.

[0015] In some embodiments of the present invention, in step (2), the particles are pulverized to an average particle size of 10-30 μm.

[0016] Preferably, in step (2), the particles are crushed to an average particle size of 20 μm.

[0017] In some embodiments of the present invention, in step (3), the mass ratio of the mixed material to the microparticles is 1:(0.01-0.03).

[0018] Preferably, in step (3), the mass ratio of the mixed material to the microparticles is 1:0.02.

[0019] Currently, most steam eye masks on the market have the problem of rapid early heating, and there is still room for improvement in terms of uniform heating. Polypropylene fiber has good compressive strength and resilience, so adding a certain amount of polypropylene fiber to the self-heating body and using a roller pressing process to mix it evenly can help improve the compaction density of the self-heating body. This is conducive to the formation of stable air channels inside the self-heating body, thus giving the self-heating body the characteristic of uniform heating.

[0020] Although polypropylene fibers can contribute to the uniform heating of self-heating elements, the surface of unmodified polypropylene fibers is hydrophobic. When used in the self-heating elements of steam eye masks, this hinders moisture penetration, reduces heating efficiency, weakens the heat therapy effect, and causes localized excessive moisture or stuffiness. To address these issues, the applicant introduced EVOH into the PP matrix and prepared a mixed material by improving the compatibility between the two through PP-g-MAH. By controlling the ratio between the raw materials, the mixed material possesses both good hydrophilicity and rigid elasticity. Furthermore, the applicant introduced O-carboxymethyl chitosan with a specific particle size into the mixed material. This material is characterized by high dispersion, biodegradability, broad-spectrum antibacterial properties, and good thermal stability, and can meet the rapid moisture absorption and wicking requirements of steam eye masks. After blending and granulation, the material was melt-spun at a controlled temperature to obtain hollow modified polypropylene fibers. PP provides strength, EVOH improves the overall elasticity of the fiber, and the O-carboxymethyl chitosan microdomains act as physical cross-linkers. The three components work synergistically to promote the formation of stable air channels inside, thereby making the heating of the self-heating element more uniform and closer to a constant temperature.

[0021] In some embodiments of the present invention, the absorbent material is silicone or sponge.

[0022] In some embodiments of the present invention, the binder is xanthan gum or sodium carboxymethyl cellulose.

[0023] In another aspect, the present invention provides a method for preparing the long-lasting constant-temperature self-heating element described in the above technical solution, comprising the following steps: S1. Mix iron powder, activated carbon, modified polypropylene fiber, water-absorbing material, vermiculite and binder, stir to obtain mixed powder, roll press to obtain core for later use; mix salt and deionized water, stir to obtain brine for later use. S2. Add the brine to the core from step S1, stir, first put it into an inner bag made of non-woven fabric with a multi-microporous oxygen-permeable membrane, then wrap it with an oxygen-barrier plastic outer bag, heat seal and cut it, and wait for the brine to disperse to obtain a long-lasting constant temperature self-heating body.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention selects iron powder, activated carbon, vermiculite and other substances as basic components, designs and adds modified polypropylene fiber, and combines it with water-absorbing materials, binders, salt and deionized water to make a self-heating body. Through the synergistic effect between the components, the self-heating body has the characteristics of being able to generate heat at a constant temperature and for a long time.

[0025] (2) In this invention, EVOH is first introduced into the PP matrix, and the compatibility between the two is improved by PP-g-MAH to prepare a mixed material. By controlling the ratio between the raw materials, the mixed material has both good hydrophilicity and hard elasticity. Furthermore, the applicant introduces O-carboxymethyl chitosan with a specific particle size into the mixed material, and after blending and granulation, the temperature is controlled to perform melt hollow spinning to obtain hollow modified polypropylene fibers. PP, EVOH and O-carboxymethyl chitosan have a synergistic effect to promote the formation of stable air channels inside, thereby making the heating of the self-heating body more uniform and closer to constant temperature. Detailed Implementation

[0026] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0027] In the following examples and comparative examples, except for the modified polypropylene fiber, all other compound monomers and related reagents used were commercially available. Specifically, the PP grade was T30S; the EVOH grade was L171B; the PP-g-MAH grade was Arkema CA100; O-carboxymethyl chitosan was purchased from Hubei Jiufenglong Chemical Co., Ltd.; xanthan gum was purchased from Renqiu Shuangcheng Chemical Products Factory; sodium carboxymethyl cellulose was purchased from Langfang Senxuan Cellulose Co., Ltd.; and the polypropylene fiber was purchased from Shandong Jinyi Building Materials Co., Ltd.

[0028] Preparation Example 1 The synthesis method of modified polypropylene fiber A includes the following steps: (1) 100g PP, 10g EVOH and 5g PP-g-MAH were dried at 80℃ for 24h and then mixed, extruded and granulated, and dried at 80℃ for 12h to obtain the mixed material for later use; (2) 20g of O-carboxymethyl chitosan was pulverized to an average particle size of 20μm and dried at 80℃ for 8h to obtain microparticles for later use; (3) Add 2g of the microparticles from step (2) to 100g of the mixed material from step (1), blend and dry (dry at 105℃ for 4h), extrude and granulate, melt and hollow spin at 195℃, cool to room temperature, and heat treat at 150℃ for 60min to obtain modified polypropylene fiber A.

[0029] Preparation Example 2 The method for synthesizing modified polypropylene fiber B is the same as that for synthesizing modified polypropylene fiber A, except that the mass of EVOH in step (1) is replaced with 4g.

[0030] Preparation Example 3 The method for synthesizing modified polypropylene fiber C is the same as the method for synthesizing modified polypropylene fiber A, except that the mass of the microparticles in step (3) is replaced with 0.8g.

[0031] Example 1 A long-lasting constant temperature self-heating body, by weight, comprises the following raw materials: 50 parts iron powder, 15 parts activated carbon, 3 parts modified polypropylene fiber A, 2 parts sponge, 6.5 parts vermiculite, 2 parts xanthan gum, 3.5 parts sodium chloride, and 15 parts deionized water.

[0032] The iron powder has a particle size of 130 mesh, and the activated carbon has a particle size of 180 mesh.

[0033] The preparation method of the long-lasting constant-temperature self-heating element in this embodiment includes the following steps: S1. Mix iron powder, activated carbon, modified polypropylene fiber A, sponge, vermiculite and xanthan gum, stir evenly to obtain mixed powder, roll press at 180℃ to obtain core for later use; mix sodium chloride and deionized water, stir evenly to obtain brine for later use. S2. Add the brine to the core from step S1 and stir for 10 minutes. First, put it into an inner bag made of non-woven fabric with a multi-microporous oxygen-permeable membrane, and then wrap it with an oxygen-barrier plastic outer bag. Heat seal and cut (thickness 2mm, length 10cm, width 6cm). After the brine is evenly dispersed, a long-lasting constant temperature self-heating body is obtained.

[0034] Example 2 A long-lasting constant temperature self-heating body, by weight, comprises the following raw materials: 40 parts iron powder, 10 parts activated carbon, 1 part modified polypropylene fiber A, 1 part sponge, 5 parts vermiculite, 1 part sodium carboxymethyl cellulose, 2 parts sodium chloride, and 10 parts deionized water.

[0035] The particle size of the iron powder and activated carbon is the same as in Example 1.

[0036] The preparation method of the long-lasting constant-temperature self-heating element in this embodiment includes the following steps: S1. Mix iron powder, activated carbon, modified polypropylene fiber A, sponge, vermiculite and sodium carboxymethyl cellulose, stir evenly to obtain mixed powder, roll press at 180℃ to obtain core for later use; mix sodium chloride and deionized water, stir evenly to obtain brine for later use. S2. Add the brine to the core from step S1 and stir for 10 minutes. First, put it into an inner bag made of non-woven fabric with a multi-microporous oxygen-permeable membrane, and then wrap it with an oxygen-barrier plastic outer bag. Heat seal and cut (thickness 2mm, length 10cm, width 6cm). After the brine is evenly dispersed, a long-lasting constant temperature self-heating body is obtained.

[0037] Example 3 A long-lasting constant temperature self-heating body, by weight, comprises the following raw materials: 60 parts iron powder, 20 parts activated carbon, 5 parts modified polypropylene fiber A, 3 parts sponge, 8 parts vermiculite, 3 parts xanthan gum, 5 parts sodium chloride, and 20 parts deionized water.

[0038] The particle size of the iron powder and activated carbon is the same as in Example 1.

[0039] The preparation method of the long-lasting constant temperature self-heating element in this embodiment is the same as that in Embodiment 1.

[0040] Example 4 This embodiment provides a long-lasting constant temperature self-heating element and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that the particle size of the iron powder is 200 mesh.

[0041] Example 5 This embodiment provides a long-lasting constant temperature self-heating element and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that the particle size of the activated carbon is 300 mesh.

[0042] Example 6 This embodiment provides a long-lasting constant temperature self-heating element and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that modified polypropylene fiber A is replaced by modified polypropylene fiber B in an equal amount.

[0043] Example 7 This embodiment provides a long-lasting constant temperature self-heating element and its preparation method. The specific implementation method is the same as that in Embodiment 1, except that modified polypropylene fiber A is replaced by modified polypropylene fiber C in an equal amount.

[0044] Comparative Example 1 This comparative example provides a long-lasting constant temperature self-heating element and its preparation method. The specific implementation method is the same as in Example 1, except that commercially available conventional polypropylene fiber is used to replace the modified polypropylene fiber A in an equal amount.

[0045] Performance testing The performance of the persistent constant temperature self-heating bodies of Examples 1-7 and Comparative Example 1 was tested, and the test results are shown in Table 1.

[0046] The heating temperature (unit: °C) and heating time (unit: min) of the self-heating bodies of Examples 1-7 and Comparative Example 1 were tested by placing thermocouple temperature probes on the self-heating bodies and recording the temperature changes within 0-45 min and the temperature at 120 min.

[0047] Table 1 As shown in Table 1, the self-heating bodies in Examples 1-3 of this invention all exhibited high maximum heating temperatures, long heating times, and near-constant heating at the maximum temperature, demonstrating the characteristics of constant and sustained heating. Specifically, Example 4 changed the particle size of the iron powder, and Example 5 changed the particle size of the activated carbon, resulting in a certain decrease in the maximum heating temperature and heating time, but with little impact on the constant heating performance. Examples 6-7 changed the addition ratio of the main raw materials EVOH and O-carboxymethyl chitosan powder during the preparation of the modified polypropylene fiber, preventing the formation of stable air channels within the self-heating body, leading to a decrease in the uniformity of heating and a certain decrease in the duration of constant heating. Comparative Example 1 used commercially available conventional polypropylene fiber to replace the modified polypropylene fiber A in equal amounts, and tests showed that the heating duration of the self-heating body decreased, and it was difficult to achieve near-constant heating.

[0048] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A long-lasting, constant-temperature self-heating element, characterized in that, The self-heating body comprises the following raw materials by weight: 40-60 parts iron powder, 10-20 parts activated carbon, 1-5 parts modified polypropylene fiber, 1-3 parts water-absorbing material, 5-8 parts vermiculite, 1-3 parts binder, 2-5 parts salt, and 10-20 parts deionized water. The method for preparing the modified polypropylene fiber includes the following steps: (1) PP, EVOH and PP-g-MAH are dried separately, then mixed, extruded and granulated, and dried to obtain a mixed material for later use; (2) O-carboxymethyl chitosan was pulverized and dried to obtain microparticles for later use; (3) Add the microparticles from step (2) to the mixed material from step (1), blend and dry, extrude and granulate, melt hollow spin at 190-200℃, cool to room temperature, heat treat at 135-145℃ for 50-70 min, and obtain modified polypropylene fiber. In step (1), the mass ratio of PP to EVOH is 1:(0.05-0.15). In step (3), the mass ratio of the mixed material to the microparticles is 1:(0.01-0.03).

2. The long-lasting constant-temperature self-heating element according to claim 1, characterized in that, The iron powder has a particle size of 120-150 mesh.

3. The long-lasting constant-temperature self-heating element according to claim 1, characterized in that, The activated carbon has a particle size of 150-200 mesh.

4. The long-lasting constant-temperature self-heating element according to claim 1, characterized in that, In step (2), the particles are crushed to an average particle size of 10-30 μm.

5. The long-lasting constant-temperature self-heating element according to claim 1, characterized in that, The absorbent material is silicone or sponge.

6. The long-lasting constant-temperature self-heating element according to claim 1, characterized in that, The binder is xanthan gum or sodium carboxymethyl cellulose.

7. A method for preparing a long-lasting constant-temperature self-heating element according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix iron powder, activated carbon, modified polypropylene fiber, water-absorbing material, vermiculite and binder, stir to obtain mixed powder, roll press to obtain core for later use; mix salt and deionized water, stir to obtain brine for later use. S2. Add the brine to the core from step S1, stir, first put it into an inner bag made of non-woven fabric with a multi-microporous oxygen-permeable membrane, then wrap it with an oxygen-barrier plastic outer bag, heat seal and cut it, and wait for the brine to disperse to obtain a long-lasting constant temperature self-heating body.

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