A constant temperature moxa sticking plaster based on phase change microcapsule-iron powder oxidation synergistic temperature control and a preparation method thereof

Abstract

This invention belongs to the technical field of external warming patch products, and discloses a constant-temperature moxibustion patch formula and its preparation method based on the synergistic temperature control of phase change microcapsules and iron powder oxidation. The constant-temperature moxibustion patch includes a patch body, which, in order of application from the skin side to the outside, comprises an artemisia heat-triggered release layer, a phase change microcapsule temperature control layer, an iron powder oxidation heating layer, and an oxygen-limiting breathable backing layer. The phase change microcapsule temperature control layer contains phase change microcapsules with a phase change temperature of 42-47℃, and the phase change microcapsules exhibit a gradient distribution in the thickness direction, with a higher content near the skin side and a lower content near the iron powder oxidation heating layer. The ratio of the total latent heat of the phase change microcapsules to the theoretical heat release of the iron powder is 0.06-0.18. This invention helps to reduce temperature peaks, prolong the duration of the suitable warming range, and improve the stability of the release of volatile components from artemisia.

Description

Technical Field

[0002] This invention relates to the field of external warming patch technology, specifically to a constant temperature moxibustion patch formula and its preparation method based on phase change microcapsules-iron powder oxidation synergistic temperature control. Background Technology

[0004] Moxibustion patches are a type of external warming patch product that combines the functional components of mugwort with a patch carrier and heating material. Compared to traditional open-flame moxibustion, they are convenient to carry, easy to use, and require no open flame. They are suitable for daily warming application to areas such as the shoulders, neck, waist, abdomen, and knees. Existing moxibustion patches typically use mugwort powder, mugwort extract, mugwort volatile oil, or mugwort floss as functional components, and provide heat through an iron powder oxidation self-heating system, allowing the mugwort components to be released under warm conditions.

[0005] Chinese patent document CN109528486A discloses a self-heating, smokeless moxibustion patch. The heating material in its self-heating layer is composed of iron powder, expanded vermiculite, activated carbon, industrial salt, water-absorbing resin, and water. Upon contact with air, it undergoes an oxidation-reduction reaction, releasing heat to provide warmth to the mugwort ointment layer. This design avoids the smoke problem associated with traditional burning moxibustion and improves ease of use.

[0006] However, existing iron powder oxidation-based moxibustion patches mainly rely on the ratio of heating materials and the structure of breathable bags to control temperature rise, resulting in a relatively crude temperature regulation method. The iron powder oxidation reaction tends to cause rapid temperature rise in the initial stage after opening due to ample oxygen supply, leading to a higher local temperature peak. Later in use, the temperature may decay rapidly due to a decrease in the iron powder oxidation rate, making it difficult to maintain a suitable temperature range for an extended period. Simultaneously, the volatile components of mugwort are easily affected by temperature fluctuations; when the temperature is too high, they are released too quickly in the early stages, with a significant decrease in aroma and volatile components later; when the temperature is too low, the release is insufficient, affecting the application experience. Furthermore, existing moxibustion patches typically only have a simple insulating layer between the heating layer and the mugwort layer, lacking an intermediate temperature control structure that can buffer heat on the skin side and compensate for heat decay during the heat dissipation phase.

[0007] Therefore, it is necessary to provide a constant-temperature moxibustion patch structure and its preparation method that can take into account the start-up heating speed, peak temperature control, continuous heating capacity and stable release of mugwort components. Summary of the Invention

[0009] The technical objective of this invention is to provide a constant temperature moxibustion patch based on phase change microcapsules-iron powder oxidation synergistic temperature control and its preparation method, so as to reduce the temperature peak in the initial stage of iron powder oxidation heating, prolong the duration of suitable warmth, and improve the stable release of volatile components of mugwort.

[0010] To achieve the above-mentioned technical objectives, the present invention provides the following technical solutions.

[0011] In a first aspect, the present invention provides a constant temperature moxibustion patch based on phase change microcapsules-iron powder oxidation synergistic temperature control, comprising a patch body, wherein the patch body comprises, in order from the skin side to the outside during use, a mugwort heat-triggered release layer, a phase change microcapsule temperature control layer, an iron powder oxidation heating layer and an oxygen-limiting breathable backing layer.

[0012] The mugwort heat-triggered release layer contains mugwort raw materials and / or a carrier of mugwort volatile components;

[0013] The phase change microcapsule temperature control layer contains phase change microcapsules with a phase change temperature of 42-47°C, and the phase change microcapsules are distributed in a gradient distribution in the thickness direction of the phase change microcapsule temperature control layer, with a high content near the skin side and a low content near the iron powder oxidation heating layer side.

[0014] The iron powder oxidation heating layer contains an oxidation heating system with iron powder as the heat source;

[0015] The oxygen-limiting and breathable backing layer is disposed on the side of the iron powder oxidation heating layer away from the skin, and is used to limit the oxygen flux entering the iron powder oxidation heating layer;

[0016] The ratio of the total latent heat of the phase change microcapsules to the theoretical heat release calculated based on the complete oxidation of iron powder in the iron powder oxidation heating layer to ferric oxide is 0.06 to 0.18.

[0017] Specifically, the phase change microcapsule includes a phase change core material and a wall material covering the phase change core material;

[0018] The phase change core material is paraffin wax, fatty acid ester, fatty alcohol, polyethylene glycol, or a combination thereof;

[0019] The wall material is melamine-formaldehyde resin, urea-formaldehyde resin, polyurethane, polymethyl methacrylate, silicon dioxide, or a combination thereof;

[0020] The phase change microcapsules have an average particle size of 5–80 μm and an encapsulation efficiency of 70–95%.

[0021] Specifically, the phase change microcapsule temperature control layer includes a high phase change content region near the skin side and a low phase change content region near the iron powder oxidation heating layer side;

[0022] The mass fraction of phase change microcapsules in the high phase change content region is 35-65%;

[0023] The mass fraction of phase change microcapsules in the low phase change content region is 15-35%;

[0024] Furthermore, the mass fraction of phase change microcapsules in the high phase change content region is 1.5 to 3.5 times that in the low phase change content region.

[0025] Specifically, the phase change microcapsule temperature control layer also includes thermally conductive fillers and elastic, breathable binders;

[0026] The thermally conductive filler is far-infrared ceramic powder, boron nitride, alumina, graphene microplates or a combination thereof, and the mass fraction of the thermally conductive filler in the phase change microcapsule temperature control layer is 3-15%.

[0027] The elastic and breathable adhesive is medical polyurethane, acrylate pressure-sensitive adhesive, silicone gel, or a combination thereof.

[0028] Specifically, the iron powder oxidation heating layer comprises, by mass parts: 45-60 parts iron powder, 4-10 parts activated carbon, 10-25 parts vermiculite, 1.5-5 parts inorganic salt, 10-22 parts water, and 1-5 parts water-absorbing resin;

[0029] The inorganic salt is sodium chloride, potassium chloride, sodium sulfate, or a combination thereof;

[0030] The water-absorbing resin is a polyacrylate water-absorbing resin, a starch-grafted water-absorbing resin, a polyvinyl alcohol water-absorbing resin, or a combination thereof.

[0031] Specifically, the mugwort heat-triggered release layer comprises, by mass, 30-70 parts of mugwort powder or mugwort floss powder, 3-15 parts of mugwort volatile oil inclusion complex, and 10-40 parts of breathable film-forming matrix;

[0032] The volatile oil inclusion complex of Artemisia argyi is an inclusion complex or adsorption complex formed by Artemisia argyi volatile oil and one or more of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, porous starch, and porous silica.

[0033] The breathable film-forming matrix is ​​hydroxypropyl methylcellulose, gelatin, sodium alginate, polyvinyl alcohol, medical polyurethane, or a combination thereof;

[0034] The mugwort heat-triggered release layer also includes one or more of the following: 1-8 parts ginger extract, 0.5-5 parts cinnamon extract, and 1-8 parts far-infrared ceramic powder.

[0035] Specifically, the oxygen-limiting and breathable backing layer is one of the following: microporous polyethylene membrane, microporous polypropylene membrane, polyurethane breathable membrane, and nonwoven fabric-microporous membrane composite layer, and the oxygen permeability of the oxygen-limiting and breathable backing layer is 2000-9000 cm⁻¹. 3 / (m 2 24h 0.1MPa);

[0036] The oxygen-limiting and breathable backing layer is provided with oxygen flux zones, and the oxygen permeability in the central area of ​​the body is lower than that in the edge area of ​​the body.

[0037] Specifically, the patch also includes a release protective layer and an annular positioning adhesive layer. The release protective layer is peelably covered on the side of the mugwort heat-triggered release layer and the annular positioning adhesive layer that is close to the skin. The annular positioning adhesive layer surrounds the outer periphery of the mugwort heat-triggered release layer, so that the central area of ​​the mugwort heat-triggered release layer is opposite to the skin during use and is not covered by pressure-sensitive adhesive.

[0038] The patch is sealed in an oxygen-barrier outer packaging bag before use. The oxygen-barrier outer packaging bag is an aluminum-plastic composite film bag or an aluminized composite film bag, and the oxygen volume fraction in the oxygen-barrier outer packaging bag is not higher than 2%.

[0039] Furthermore, the present invention also provides a method for preparing the constant temperature moxibustion patch described in the first aspect, comprising the following steps:

[0040] S1. Prepare phase change microcapsules by emulsifying and dispersing the phase change core material in an aqueous system and forming a coating wall material through in-situ polymerization, interfacial polymerization or sol-gel reaction to obtain phase change microcapsules with a phase change temperature of 42-47℃.

[0041] S2. The phase change microcapsules are prepared into a phase change microcapsule slurry, and a phase change microcapsule temperature control layer with a gradient distribution of phase change microcapsule content in the thickness direction is formed by multiple coating, dual-channel slit coating or layered calendering.

[0042] S3. Mix the mugwort raw material and / or the mugwort volatile component carrier with the breathable film-forming matrix to form a mugwort heat-triggered release layer;

[0043] S4. Mix iron powder, activated carbon, vermiculite, inorganic salts, water and water-absorbing resin to form an iron powder oxidation heating layer;

[0044] S5. The mugwort heat-triggered release layer, the phase change microcapsule temperature control layer, the iron powder oxidation heating layer and the oxygen-limiting breathable backing layer are sequentially composited to obtain the patch.

[0045] Specifically, in step S2, a low content of phase change microcapsule slurry is first applied to the side near the iron powder oxidation heating layer, and then a high content of phase change microcapsule slurry is applied to the side near the skin.

[0046] The solid content of the phase change microcapsules in the low-content phase change microcapsule slurry is 15-35%;

[0047] The high-content phase change microcapsule slurry has a solid content of 35-65% in the phase change microcapsules.

[0048] The drying temperature after each coating should not exceed 40℃.

[0049] Specifically, in step S3, the volatile oil of Artemisia argyi is first encapsulated or adsorbed with β-cyclodextrin, hydroxypropyl-β-cyclodextrin, porous starch or porous silica to obtain the volatile oil inclusion complex of Artemisia argyi. Then, the volatile oil inclusion complex of Artemisia argyi is mixed with Artemisia argyi powder or Artemisia argyi powder and a breathable film-forming matrix to form the heat-triggered release layer of Artemisia argyi.

[0050] Specifically, in step S4, the moisture content of the iron powder oxidation heating layer is controlled to be 12-24%. After mixing, it is allowed to stand and be balanced for 0.5-4 hours in a nitrogen environment or a low oxygen environment with an oxygen volume fraction of no more than 5% before being filled or compounded.

[0051] Specifically, after step S5, the patch is sealed inside an oxygen-barrier outer packaging bag.

[0052] This invention employs a phase change microcapsule temperature control layer between the mugwort heat-triggered release layer and the iron powder oxidation heating layer. The phase change microcapsules are distributed in a gradient along their thickness, with a higher content near the skin and a lower content near the iron powder oxidation heating layer. This allows the heat generated by the iron powder oxidation heating layer to be rapidly conducted through the low phase change content area, followed by heat absorption buffering and heat release compensation near the skin from the high phase change content area. This balances the rate of temperature rise after opening with control of the peak temperature on the skin side. Simultaneously, by limiting the heat matching ratio between the total latent heat of the phase change microcapsules and the theoretical heat release of the iron powder, the heat absorption and release capacity of the phase change microcapsules is matched with the heat release capacity of the iron powder oxidation, reducing initial temperature overshoot and subsequent temperature decay. Combined with the oxygen-limiting breathable backing layer regulating oxygen flux, the iron powder oxidation reaction rate is further smoothed, allowing the patch to maintain a suitable temperature range for a longer period and promoting the continuous and stable release of volatile components from the mugwort, thus improving application comfort and temperature stability. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the layered structure of the constant temperature moxibustion patch of the present invention.

[0055] Figure 2 This is a schematic diagram of the preparation method of the constant temperature moxibustion patch of the present invention. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are only used to illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the technical solution of the present invention, those skilled in the art can make adaptive adjustments to the thickness of each layer, component ratio, composite method and packaging specifications according to the application site, patch size, target heating time, production equipment conditions and product specifications.

[0058] I. Terminology Explanation

[0059] To facilitate understanding of the technical solution of this invention, some terms involved in this specific embodiment are explained below. Unless otherwise specifically defined, the following terms are only used to explain the embodiments of this invention and should not be construed as additional limitations on the scope of protection.

[0060] The patch refers to the main structure of the constant temperature moxibustion patch after the oxygen-barrier outer packaging bag is torn off. It includes at least a mugwort heat-triggered release layer, a phase change microcapsule temperature control layer, an iron powder oxidation heating layer, and an oxygen-limiting and breathable backing layer. In some embodiments, it may also include auxiliary structures such as a release protective layer and an annular positioning adhesive layer.

[0061] "Skin side" refers to the side of the patch that is closest to the skin during use; "outer side" refers to the side of the patch that is furthest from the skin and facing the external environment. The instruction manual's description of the layers being "installed sequentially from the skin side to the outer side" is based on the orientation of the patch under normal application conditions.

[0062] The mugwort heat-triggered release layer refers to a functional layer containing mugwort powder, mugwort floss powder, mugwort volatile oil inclusion complexes, or other mugwort volatile component carriers. Under the heat transferred by the phase change microcapsule temperature control layer, this layer gradually releases the volatile components of mugwort, creating a warm patch application experience.

[0063] Phase change microcapsules are microparticles formed by using a phase change material as the core material and a resin-based or inorganic shell material as the wall material. When the temperature reaches near its phase change temperature, the phase change core material absorbs or releases latent heat through a solid-liquid phase change, thereby buffering temperature fluctuations within the microcapsule.

[0064] Phase transition temperature refers to the temperature range within which the phase change core material inside the phase change microcapsule undergoes a phase transition. In this embodiment, the phase transition temperature of the phase change microcapsule is controlled at 42–47°C to match the suitable temperature range for application to the human body.

[0065] The phase change microcapsule temperature-controlling layer refers to a layered structure containing phase change microcapsules located between the mugwort heat-triggered release layer and the iron powder oxidation heating layer. Its function is to absorb, buffer, and re-release the heat generated by the iron powder oxidation heating layer, thereby maintaining a relatively stable surface temperature on the skin contact side.

[0066] The thickness gradient distribution refers to the fact that the phase change microcapsules are not uniformly distributed along the thickness direction of the phase change microcapsule temperature control layer, but rather have a higher content near the skin and a lower content near the iron powder oxidation heating layer. This structure is used to improve the temperature buffering capacity near the skin while ensuring the rapid heating rate at the start of the patch application.

[0067] The high phase change content region refers to the area in the phase change microcapsule temperature control layer that is closer to the skin and has a higher mass fraction of phase change microcapsules; the low phase change content region refers to the area in the phase change microcapsule temperature control layer that is closer to the iron powder oxidation heating layer and has a lower mass fraction of phase change microcapsules.

[0068] The iron powder oxidation heating layer refers to a heating layer that uses the oxidation reaction of iron powder as the main heat source. It typically includes iron powder, activated carbon, vermiculite, inorganic salts, water, and water-absorbing resin. During use, oxygen from the air enters this layer through the oxygen-limiting and breathable backing layer, undergoes a slow oxidation reaction with the iron powder, and releases heat.

[0069] An oxygen-limiting and breathable backing layer refers to a backing structure placed outside the iron powder oxidation heating layer that allows a certain amount of oxygen to pass through but restricts the rate of oxygen entry. This layer regulates the iron powder oxidation reaction rate by controlling the oxygen flux, thereby reducing the temperature peak and prolonging the heating duration.

[0070] Oxygen permeability refers to the volume of oxygen allowed to pass through a unit area of ​​membrane material per unit time under specified test conditions. In this embodiment, oxygen permeability is used to characterize the degree to which the oxygen-limiting and breathable backing layer regulates the oxygen supply capacity of the iron powder oxidation heating layer.

[0071] Oxygen-barrier outer packaging bags are packaging structures used for sealed preservation of skin patches before use. Their oxygen-barrier properties prevent the iron powder oxidation heating layer from reacting prematurely during storage. When the oxygen-barrier outer packaging bag is torn open during use, air enters the skin patch, and the iron powder oxidation heating layer begins to heat up.

[0072] The heat matching ratio refers to the ratio between the total latent heat of phase change microcapsules and the theoretical heat release of iron powder in the iron powder oxidation heating layer. This indicates that the theoretical heat release is only used for the design and comparative calculation of the heat matching ratio and does not imply that the iron powder must be completely oxidized during the application of the patch. This parameter is used to measure the matching relationship between the temperature control capability of the phase change microcapsule and the heat release capability of iron powder oxidation, and its calculation formula is:

[0073]

[0074] In the formula, This refers to the heat matching ratio; The latent heat of phase change microcapsules in the adherent is expressed in J. This represents the theoretical heat release in the iron powder oxidation heating layer, calculated based on the complete oxidation of iron powder to ferric oxide, expressed in J.

[0075] The surface temperature on the skin contact side refers to the temperature of the surface of the patch closest to the skin during simulated or actual application. This temperature is used to evaluate the patch's heating rate, peak temperature, suitable temperature duration, and application safety.

[0076] II. Overall Structure

[0077] like Figure 1 As shown, this embodiment provides a constant temperature moxibustion patch based on phase change microcapsules and iron powder oxidation synergistic temperature control, including a patch body 100. When in use, the patch body 100 includes, from the skin side to the outside, a mugwort heat-triggered release layer 10, a phase change microcapsule temperature control layer 20, an iron powder oxidation heating layer 30, and an oxygen-limiting breathable backing layer 40.

[0078] Before use, the patch 100 is sealed in an oxygen-barrier outer packaging bag. When using, tear open the oxygen-barrier outer packaging bag, and air enters the iron powder oxidation heating layer 30 through the oxygen-limiting and breathable backing layer 40. The iron powder slowly oxidizes and releases heat in the presence of oxygen and moisture. The heat is regulated by the phase change microcapsule temperature control layer 20 and then transferred to the mugwort heat-triggered release layer 10, so that the mugwort raw material or the mugwort volatile component carrier continuously releases volatile components under warm conditions.

[0079] The mugwort heat-triggered release layer 10 is disposed on the side closest to the skin and contains mugwort raw materials and / or a carrier of mugwort volatile components. The mugwort raw materials can be mugwort leaf powder, mugwort floss powder, or mugwort leaf extract powder; the mugwort volatile component carrier can be mugwort volatile oil inclusion complex, mugwort volatile oil porous adsorbent, or mugwort volatile oil microcapsules. The mugwort heat-triggered release layer 10 does not directly undertake the main heat release function, but slowly releases heat at the phase change plateau temperature, so that the patch maintains a stable mugwort scent and warm application sensation over a longer period of use.

[0080] The phase change microcapsule temperature control layer 20 is located between the Artemisia argyi heat-triggered release layer 10 and the iron powder oxidation heating layer 30, and contains phase change microcapsules with a phase change temperature of 42-47°C. The phase change microcapsule temperature control layer 20 is used to absorb excess heat generated during the initiation and intermediate stages of the iron powder oxidation heating layer 30, and releases the stored latent heat after the iron powder oxidation rate decreases, thereby reducing the peak temperature fluctuation on the skin side and maintaining the surface temperature on the skin contact side within a suitable application range.

[0081] The iron powder oxidation heating layer 30 contains an oxidation heating system with iron powder as the heat source. This system includes iron powder, activated carbon, vermiculite, inorganic salts, water, and water-absorbing resin. Iron powder is the main exothermic component; activated carbon improves oxygen distribution and heat conduction channels; vermiculite provides insulation and heat storage; inorganic salts promote iron powder oxidation; water provides the humidity required for the oxidation reaction; and water-absorbing resin adjusts the system's moisture content and reduces reaction unevenness caused by localized free water.

[0082] An oxygen-limiting and breathable backing layer 40 covers the side of the iron powder oxidation heating layer 30 away from the skin, and is used to limit the oxygen flux entering the iron powder oxidation heating layer 30. By controlling the oxygen permeability, the temperature surge caused by the excessively rapid initial iron powder oxidation reaction can be reduced, while the heating duration can be extended. The oxygen-limiting and breathable backing layer 40 can be a microporous polyethylene membrane, a microporous polypropylene membrane, a polyurethane breathable membrane, or a non-woven fabric-microporous membrane composite layer.

[0083] In some embodiments, the patch 100 further includes a release protective layer 50 and an annular positioning adhesive layer 60. The release protective layer 50 peelably covers the skin side of the mugwort heat-triggered release layer 10 and the annular positioning adhesive layer 60; wherein, the annular positioning adhesive layer 60 is used to fix the patch 100 to the area to be applied to the human body during use, and to ensure that the edge area of ​​the patch 100 forms a stable fit with the skin, reducing displacement, lifting, or detachment caused by human movement during use. Since the annular positioning adhesive layer 60 surrounds the outer periphery of the mugwort heat-triggered release layer 10 and does not cover the central area of ​​the mugwort heat-triggered release layer 10, it can avoid the problems of reduced breathability, obstructed release of volatile components, or local stuffiness caused by the pressure-sensitive adhesive directly covering the mugwort release area, allowing the mugwort heat-triggered release layer 10 to be more fully aligned with the skin side space and maintain a better heat release effect.

[0084] The release layer 50 is used to cover and protect the skin-side surfaces of the annular positioning adhesive layer 60 and the mugwort heat-triggered release layer 10 before the patch 100 is used. This prevents the pressure-sensitive adhesive layer from sticking, becoming contaminated, or losing its adhesion during storage, transportation, or handling. It also reduces powder shedding from the surface of the mugwort heat-triggered release layer 10 and the impact of external moisture and dust on the application surface. During use, the user peels off the release layer 50, exposing the annular positioning adhesive layer 60, which is then adhered to the skin surface, thus completing the positioning and application of the patch 100.

[0085] III. Phase Change Microcapsule Temperature Control Layer

[0086] like Figure 2 As shown, the phase change microcapsule temperature control layer 20 is disposed between the mugwort heat-triggered release layer 10 and the iron powder oxidation heating layer 30, and is used to buffer the heat generated by the iron powder oxidation heating layer 30 and reduce temperature fluctuations on the skin side. The phase change microcapsules in the phase change microcapsule temperature control layer 20 are distributed in a gradient along the thickness direction, that is, the content of phase change microcapsules is higher near the mugwort heat-triggered release layer 10 and the skin side, and lower near the iron powder oxidation heating layer 30.

[0087] In practice, high-content phase change microcapsule slurry and low-content phase change microcapsule slurry can be prepared separately. The mass fraction of phase change microcapsules in the high-content phase change microcapsule slurry is 35-65%, and the mass fraction of phase change microcapsules in the low-content phase change microcapsule slurry is 15-35%. First, the high-content phase change microcapsule slurry is coated on the release substrate and dried at low temperature. Then, the low-content phase change microcapsule slurry is coated on one side and dried at low temperature to form a double-layer composite phase change microcapsule temperature control layer 20. When applying the composite moxibustion patch, the side with high-content phase change microcapsules faces the mugwort heat-triggered release layer 10 and the skin side, and the side with low-content phase change microcapsules faces the iron powder oxidation heating layer 30.

[0088] Alternatively, a dual-channel slit coating method can be used, in which high-content phase change microcapsule slurry and low-content phase change microcapsule slurry are fed into the coating head separately. During the coating process, the upper and lower layers of the two slurries are controlled so that the high-content slurry is located on the skin side and the low-content slurry is located on the heating side. After drying, a phase change microcapsule temperature control layer 20 with a thickness gradient is formed in one step.

[0089] After adopting the above gradient setting, the low phase change content area near the iron powder oxidation heating layer 30 can reduce the initial thermal resistance and allow heat to be transferred to the inside of the patch more quickly; the high phase change content area near the skin can absorb the peak temperature heat, suppress the temperature overshoot on the skin contact side, and release latent heat after the iron powder oxidation heat release weakens, so that the mugwort heat triggering release layer 10 is in a more stable moxibustion temperature range.

[0090] Phase change microcapsules comprise a phase change core material and a wall material coating the core material. The core material can be paraffin wax, fatty acid esters, fatty alcohols, polyethylene glycol, or combinations thereof, while the wall material can be melamine-formaldehyde resin, urea-formaldehyde resin, polyurethane, polymethyl methacrylate, silica, or combinations thereof. The average particle size of the phase change microcapsules is 5–80 μm, with an encapsulation efficiency of 70–95%. When the particle size of the phase change microcapsules is too small, the preparation cost increases and the viscosity of the coating slurry rises; when the particle size is too large, the surface smoothness of the coating decreases, and it may cause localized capsule rupture when the capsule is bent. Therefore, in this embodiment, phase change microcapsules with an average particle size of 15–50 μm are preferred.

[0091] The phase change microcapsule temperature control layer 20 may also include a thermally conductive filler and an elastic, breathable adhesive. The thermally conductive filler is far-infrared ceramic powder, boron nitride, alumina, graphene microsheets, or a combination thereof, and its mass fraction in the phase change microcapsule temperature control layer 20 is 3–15%. The elastic, breathable adhesive is medical-grade polyurethane, acrylic pressure-sensitive adhesive, silicone gel, or a combination thereof. The thermally conductive filler is used to reduce the thermal resistance between the phase change microcapsule particles, making the heat absorption and release processes of the temperature control layer more uniform; the elastic, breathable adhesive is used to maintain the flexibility of the temperature control layer and prevent interlayer cracking when the patch is bent.

[0092] For ease of design and quality control, this embodiment defines the ratio of the total latent heat of the phase change microcapsules to the theoretical heat release of the iron powder in the iron powder oxidation heating layer as the heat matching ratio. It satisfies:

[0093]

[0094] In the formula, This refers to the heat matching ratio; The latent heat of phase change microcapsules in the adherent is expressed in J. This represents the theoretical heat release in the iron powder oxidation heating layer, calculated based on the complete oxidation of iron powder to ferric oxide, expressed in J.

[0095] in, Calculate according to the following formula:

[0096]

[0097] In the formula, The mass of the phase change core material within the phase change microcapsule in the patch is expressed in grams. The latent heat of phase change of the phase change core material is expressed in J / g.

[0098] Theoretical heat release of iron powder Based on the quality of iron powder and the oxidation state of iron... The reaction heat is converted. In actual production, a database of heat release per unit mass of the iron powder heating system can also be established through standard calorimetry testing, and then the measured heat release can be used as a process control parameter. In this embodiment, The control range is 0.06–0.18. If Below 0.06, the phase change heat absorption capacity is insufficient, resulting in a higher peak temperature on the skin side; if If the temperature is above 0.18, the heat is excessively absorbed during the start-up phase, the heating time is prolonged, and the temperature sensation after application is insufficient.

[0099] IV. Artemisia heat-triggered release layer

[0100] The heat-triggered release layer 10 of Artemisia argyi comprises, by weight, 30-70 parts of Artemisia argyi powder or Artemisia argyi floss powder, 3-15 parts of Artemisia argyi volatile oil inclusion complex, and 10-40 parts of a breathable film-forming matrix. In some embodiments, the heat-triggered release layer 10 of Artemisia argyi further includes one or more of the following: 1-8 parts of ginger extract, 0.5-5 parts of cinnamon extract, and 1-8 parts of far-infrared ceramic powder.

[0101] The inclusion complex of Artemisia argyi volatile oil can be an inclusion complex or adsorption complex formed by Artemisia argyi volatile oil and one or more of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, porous starch, and porous silica. The reason for using inclusion complexes or adsorption complexes is that Artemisia argyi volatile oil itself is volatile and easily oxidized; direct addition to the patch can easily lead to degradation during storage. Encapsulation with cyclodextrin or adsorption with porous materials can improve the stability of the volatile components and allow them to be gradually released under warm conditions.

[0102] The breathable film-forming matrix can be hydroxypropyl methylcellulose, gelatin, sodium alginate, polyvinyl alcohol, medical polyurethane, or a combination thereof. The breathable film-forming matrix forms a continuous porous network in the Artemisia argyi heat-triggered release layer 10, which disperses and fixes the Artemisia argyi powder or Artemisia argyi floss powder, while allowing volatile components to be released to the skin side and the surrounding air.

[0103] In one specific embodiment, the preparation steps of the Artemisia argyi volatile oil inclusion complex are as follows: Weigh 100 parts of β-cyclodextrin, add 800 parts of deionized water, and stir at 50-60°C until a uniform suspension is formed; dissolve 10-18 parts of Artemisia argyi volatile oil in a small amount of ethanol and slowly add it dropwise to the β-cyclodextrin suspension, and stir at 45-55°C for 2-4 hours; then cool to 10-15°C and let stand for 8-12 hours, filter to collect the precipitate, vacuum dry, pulverize and sieve to obtain the Artemisia argyi volatile oil inclusion complex. The quality control of the obtained inclusion complex can be performed by odor retention rate, thermogravimetric analysis or volatile component release test.

[0104] V. Iron powder oxidation heating layer and oxygen-limiting breathable backing layer

[0105] The iron powder oxidation heating layer 30 comprises, by weight, 45-60 parts iron powder, 4-10 parts activated carbon, 10-25 parts vermiculite, 1.5-5 parts inorganic salt, 10-22 parts water, and 1-5 parts water-absorbing resin. The inorganic salt can be sodium chloride, potassium chloride, sodium sulfate, or a combination thereof. The water-absorbing resin can be polyacrylate water-absorbing resin, starch-grafted water-absorbing resin, polyvinyl alcohol water-absorbing resin, or a combination thereof.

[0106] The preferred iron powder is reduced iron powder with a particle size of 50–200 mesh. If the particle size is too large, the specific surface area is insufficient, resulting in slow heating; if the particle size is too small, the oxidation rate is too fast, easily causing a rise in the peak temperature. The preferred activated carbon is powdered activated carbon with a specific surface area of ​​800–1500 m² / g. Expanded vermiculite can be used to improve heat storage performance and form a loose structure. The moisture content of the iron powder oxidation heating layer 30 is controlled at 12–24%. If the moisture content is too low, the oxidation reaction starts slowly; if the moisture content is too high, free water blocks the pores, reducing oxygen diffusion efficiency and potentially causing localized agglomeration.

[0107] The oxygen permeability of the oxygen-limiting and breathable backing layer 40 is preferably 2000–9000 cm³ / (m²·24h·0.1MPa). When the oxygen permeability is below 2000 cm³ / (m²·24h·0.1MPa), the iron powder oxidation heating layer 30 is insufficient in oxygen supply, and the heating time is significantly prolonged; when the oxygen permeability is above 9000 cm³ / (m²·24h·0.1MPa), the initial oxidation reaction is too fast, and the peak temperature of the bonded surface is difficult to control.

[0108] In some embodiments, the oxygen-limiting and breathable backing layer 40 is provided with oxygen flux zones, where the oxygen permeability in the central region of the body patch is lower than that in the edge region. The central region is usually farther from the heat dissipation boundary and is more prone to localized high temperatures; by reducing the oxygen permeability in the central region, the central temperature peak can be suppressed, while the edge region compensates for edge heat dissipation with higher oxygen permeability, thereby improving the overall temperature uniformity of the body patch.

[0109] VI. Preparation Method

[0110] like Figure 2 As shown, the constant temperature moxibustion patch of the present invention can be prepared according to the following steps.

[0111] S1. Preparation of Phase Change Microcapsules. A phase change core material is emulsified and dispersed in an aqueous system. A coated wall material is formed through in-situ polymerization, interfacial polymerization, or sol-gel reaction, yielding phase change microcapsules with a phase change temperature of 42–47°C. Taking paraffin-fatty alcohol composite core material and melamine-formaldehyde resin wall material as examples, the core material is heated to 60°C to melt and then added to an aqueous phase containing an emulsifier. A high-speed shearing process forms an emulsion. A prepolymer is then added, and the pH is adjusted to weakly acidic, allowing the wall material to solidify into a shell on the surface of oil droplets. After cooling, filtration, washing, and drying, phase change microcapsules are obtained.

[0112] S2. Preparation of the phase change microcapsule temperature control layer. Phase change microcapsules are formulated into a phase change microcapsule slurry, and a phase change microcapsule temperature control layer 20 with a gradient distribution of phase change microcapsule content in the thickness direction is formed through multiple coating processes, dual-channel slit coating, or layered calendering. Specifically, a low-content phase change microcapsule slurry can be coated first on the release film to form the side closest to the iron powder oxidation heating layer 30; then a high-content phase change microcapsule slurry can be coated to form the side closest to the skin. The phase change microcapsule solid content in the low-content slurry is 15-35%, and the phase change microcapsule solid content in the high-content slurry is 35-65%. The drying temperature after each coating should not exceed 40℃ to avoid melting and migration of the phase change core material or thermal deformation of the wall material.

[0113] S3. Preparation of the Artemisia argyi thermally triggered release layer. First, Artemisia argyi volatile oil is encapsulated or adsorbed with β-cyclodextrin, hydroxypropyl-β-cyclodextrin, porous starch, or porous silica to obtain an Artemisia argyi volatile oil inclusion complex. Then, the Artemisia argyi volatile oil inclusion complex is mixed with Artemisia argyi powder or Artemisia argyi floss powder and a breathable film-forming matrix to form a slurry. This slurry is coated onto the skin-side of the phase change microcapsule temperature-controlled layer 20 and dried to form the Artemisia argyi thermally triggered release layer 10. Alternatively, the Artemisia argyi thermally triggered release layer 10 can be composited with the phase change microcapsule temperature-controlled layer 20 using a calendering process.

[0114] S4. Preparation of the iron powder oxidation heating layer. Iron powder, activated carbon, vermiculite, inorganic salts, water, and water-absorbing resin are mixed according to a set ratio. During mixing, the activated carbon, vermiculite, and water-absorbing resin are premixed first, then the iron powder and inorganic salts are added. Finally, water is sprayed in and stirred at low speed to ensure uniform moisture distribution. After mixing, the mixture is allowed to stand and equilibrate for 0.5–4 hours in a nitrogen atmosphere or a low-oxygen environment with an oxygen volume fraction not exceeding 5% to stabilize the system's moisture content. Then, it is filled or pressed to form the iron powder oxidation heating layer 30.

[0115] S5. Composite Packaging. The Artemisia argyi thermally triggered release layer 10, the phase change microcapsule temperature control layer 20, the iron powder oxidation heating layer 30, and the oxygen-limiting breathable backing layer 40 are sequentially composited to obtain the patch 100. An annular positioning adhesive layer 60 and a release protective layer 50 are applied to the skin side of the patch. After visual inspection, temperature rise sampling inspection, and sealing inspection, the composite patch 100 is sealed in an aluminum-plastic composite film bag or an aluminized composite film bag, with the oxygen volume fraction inside the oxygen-barrier outer packaging bag controlled to be no higher than 2%.

[0116] VII. Specific Implementation Examples and Comparative Examples

[0117] The following examples illustrate the effects of different formulations and structures on temperature rise stability, sustained heating performance, and the volatilization and release properties of Artemisia argyi. All patches were 90mm × 120mm in size, with an effective heating area of ​​65mm × 85mm. The testing environment was 25℃ and 60% relative humidity. Temperature test points were set at the center point and four edge points on the skin contact side of the patch. The temperature at the center point and the average temperature at the five points were recorded. The temperature results in the table are the average values ​​of three samples.

[0118] 7.1 Example 1

[0119] The patch of Example 1 was prepared according to the following formulation.

[0120] The phase change microcapsules use paraffin-fatty alcohol composite core material microcapsules with a phase change temperature of 44.5℃, an average particle size of 28μm, an encapsulation efficiency of 86%, and a latent heat of phase change of 150J / g. The total thickness of the phase change microcapsule temperature control layer is 0.75mm, with a high phase change content region containing 50% phase change microcapsules and a low phase change content region containing 25% phase change microcapsules, with a thickness ratio of 1:1 between the high and low phase change content regions. 6% far-infrared ceramic powder and the remainder medical-grade polyurethane binder are added to the temperature control layer. Calculations show that... It is 0.11.

[0121] The iron powder oxidation heating layer comprises, by mass, 52 parts iron powder, 7 parts activated carbon, 18 parts expanded vermiculite, 3 parts sodium chloride, 17 parts water, and 3 parts polyacrylate water-absorbing resin, with a moisture content of 18%.

[0122] The heat-triggered release layer of Artemisia argyi comprises, by weight: 50 parts Artemisia argyi powder, 8 parts Artemisia argyi volatile oil β-cyclodextrin inclusion complex, 4 parts ginger extract, 2 parts cinnamon extract, 20 parts hydroxypropyl methylcellulose, 10 parts gelatin, and 3 parts far-infrared ceramic powder. The oxygen-limiting and breathable backing layer uses a microporous polyethylene membrane with an oxygen permeability of 5200 cm⁻¹. 3 / (m 2 ·24h·0.1MPa).

[0123] 7.2 Example 2

[0124] Example 2 is basically the same as Example 1, except that: the mass fraction of phase change microcapsules in the high phase change content region of the phase change microcapsule temperature control layer is 60%, and the mass fraction of phase change microcapsules in the low phase change content region is 30%; the total thickness of the temperature control layer is 0.80 mm. The oxygen permeability of the oxygen-limiting and breathable backing layer is 0.16. 3 / (m 2 ·24h·0.1MPa).

[0125] 7.3, Example 3

[0126] Example 3 is basically the same as Example 1, except that: the mass fraction of phase change microcapsules in the high phase change content region of the phase change microcapsule temperature control layer is 40%, and the mass fraction of phase change microcapsules in the low phase change content region is 20%; the total thickness of the temperature control layer is 0.65 mm. The value is 0.075. The oxygen-limiting and breathable backing layer is a non-woven fabric-microporous membrane composite layer with an oxygen permeability of 6500 cm⁻¹. 3 / (m 2 ·24h·0.1MPa).

[0127] 7.4 Comparative Example 1

[0128] Comparative Example 1 does not have a phase change microcapsule temperature control layer. Instead, it has an ordinary non-woven fabric isolation layer between the Artemisia argyi thermal trigger release layer and the iron powder oxidation heating layer. The rest of the formulation is the same as in Example 1.

[0129] 7.5, Comparative Example 2

[0130] Comparative Example 2 included a phase change microcapsule temperature control layer, but the phase change microcapsules were uniformly distributed along the thickness of the temperature control layer, and the total amount of phase change microcapsules added was the same as in Example 1. The value is 0.11, and the rest of the formulation is the same as in Example 1.

[0131] 7.6 Comparative Example 3

[0132] Comparative Example 3 features a gradient phase change microcapsule temperature control layer, but The value was 0.025, meaning the amount of phase change microcapsules added was significantly lower than in Example 1, while the rest of the formulation was the same as in Example 1.

[0133] 7.7, Comparative Example 4

[0134] Comparative Example 4 features a gradient phase change microcapsule temperature control layer, but The value was 0.25, meaning the amount of phase change microcapsules added was significantly higher than in Example 1, while the rest of the formulation was the same as in Example 1.

[0135] VIII. Testing Methods

[0136] 8.1 Temperature Rise Test: Remove the sample from the oxygen-barrier outer packaging bag, remove the release liner, and place it flat on the constant temperature test bench with the skin contact side facing upwards. Use a patch thermocouple to record the temperature at the center point and four edge points of the skin contact side for 6 hours. The test environment is 25℃, relative humidity 60%, and air velocity not exceeding 0.2m / s. It should be noted that in this embodiment, the phase change temperature of the phase change microcapsules is 42–47℃, used to absorb excess heat and inhibit further rapid temperature rise during the exothermic oxidation of iron powder. The 42–48℃ maintenance time mentioned in the temperature rise test refers to the duration during which the output temperature of the moxibustion patch remains within the effective warm range. This range is the overall heat output performance evaluation range of the product and is not equivalent to the phase change temperature range of the phase change microcapsule core material.

[0137] 8.2 Temperature Uniformity Test: Take the center point temperature and the temperatures of the four edge points at 60 minutes, 120 minutes, and 240 minutes after use, and calculate the temperature range at five points. The smaller the range, the more uniform the temperature distribution on the patch surface.

[0138] 8.3. Release Test of Volatile Components from Artemisia argyi: The patch was placed in a sealed release chamber, with the temperature maintained by the patch's own heating. Gas phase samples were collected at 1 hour, 2 hours, 4 hours, and 6 hours. The relative release amounts of representative volatile components such as eucalyptol, borneol, and camphor were detected using gas chromatography. The release amount at 1 hour in Example 1 was normalized to 100.

[0139] 8.4. Application Observation: A combination of observation through application to ex vivo pigskin and short-term application to volunteers' forearms was used to record skin erythema, stinging, burning discomfort, and other symptoms 4 hours after application. This test is only for evaluating temperature rise and formulation irritation trends; actual products should undergo a complete safety evaluation according to the corresponding product category.

[0140] IX. Test Results

[0141] 9.1 Key parameters of the embodiments and comparative examples are shown in Table 1.

[0142] Table 1 shows the key structural parameters of the embodiments and comparative examples.

[0143]

[0144] 9.2 The temperature rise test results of the examples and comparative examples are shown in Table 2.

[0145] Table 2 shows the temperature rise test results.

[0146]

[0147] As shown in Table 2, Examples 1 to 3 all reached temperatures above 40°C within approximately 30 minutes and maintained a patch temperature range of 42–48°C for a considerable period. Comparative Example 1, without a phase change microcapsule temperature control layer, achieved a maximum center temperature of 55.2°C, indicating a significantly higher temperature in the central area and a five-point temperature difference of 5.8°C, demonstrating that a simple insulating layer alone is insufficient for stable skin-side temperature control. Comparative Example 2, while incorporating a phase change microcapsule temperature control layer, employed a uniformly distributed structure, resulting in slower temperature rise during the initial stage and less stable temperature control compared to Example 1 during the mid-term. This suggests that a gradient distribution along the thickness direction is beneficial for balancing initial speed and peak temperature buffering. Comparative Example 3… If the temperature is too low, the latent heat of phase change is insufficient, and the peak temperature remains too high. (Comparative Example 4) The temperature was too high; the center temperature was only 36.8℃ after 30 minutes, resulting in insufficient warmth during initial use.

[0148] 9.3 The results of the volatile component release tests of the examples and comparative examples are shown in Table 3.

[0149] Table 3 shows the results of the volatile component release test.

[0150]

[0151] As shown in Table 3, Examples 1 to 3 exhibited relatively stable release of volatile components from Artemisia argyi within 1 to 4 hours. Comparative Examples 1 and 3, due to their higher temperature peaks, showed higher initial release rates, but the release rate decreased rapidly in the later stages. Comparative Example 4, due to insufficient initial heating, had a lower release rate after 1 hour; although the later release was more stable, the initial application experience was weaker. This indicates that the heat matching relationship between the iron powder oxidation heating layer, the gradient phase change microcapsule temperature control layer, and the Artemisia argyi heat-triggered release layer helps to achieve a relatively stable warming release process.

[0152] 9.4 The results of the patch application observations for the examples and comparative examples are shown in Table 4.

[0153] Table 4 shows the results of the patch application observation.

[0154]

[0155] As shown in Table 4, under the test conditions described in this embodiment, the temperature peak and the incidence of application discomfort in the embodiment group were lower than those in the comparative group.

[0156] In summary, when the patch is sequentially configured with an artemisia heat-triggered release layer, a phase change microcapsule temperature control layer, an iron powder oxidation heating layer, and an oxygen-limiting breathable backing layer from the skin side outwards, and the phase change microcapsules are arranged in a gradient distribution with a high content near the skin side and a low content near the iron powder oxidation heating layer in the thickness direction of the phase change microcapsule temperature control layer, while controlling the ratio of the total latent heat of the phase change microcapsules to the theoretical heat release of the iron powder to be 0.06 to 0.18, the patch can heat up to the effective temperature range in a short time and maintain a relatively stable surface temperature on the skin contact side for a longer period of time thereafter.

[0157] Furthermore, by using the mugwort volatile oil inclusion complex and the breathable film-forming matrix to form the mugwort heat-triggered release layer, the loss of volatile components during storage can be reduced, and they can be continuously released under warm application conditions. By controlling the rate at which oxygen enters the iron powder oxidation heating layer through the oxygen-limiting breathable backing layer, the temperature peak caused by the excessively rapid heat release in the early stage of iron powder oxidation can be reduced. Through the latent heat absorption and release effect of the phase change microcapsule temperature control layer, heat can be absorbed during the peak period of iron powder heat release and heat can be compensated during the heat release decay period, making the temperature curve of the patch smoother.

[0158] The structural composition, preparation method, temperature control mechanism, and usage effects of the present invention have been described above in conjunction with the accompanying drawings, embodiments, and comparative examples. It should be understood that the above embodiments are merely preferred implementations listed for the purpose of illustrating the technical solution of the present invention and do not constitute a limitation on the scope of protection of the present invention. For those skilled in the art, any adaptive adjustments made without departing from the core concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A constant-temperature moxibustion patch based on phase change microcapsules-iron powder oxidation synergistic temperature control, characterized in that, The patch includes, in order from the skin side to the outside during use, a mugwort heat-triggered release layer, a phase change microcapsule temperature control layer, an iron powder oxidation heating layer, and an oxygen-limiting breathable backing layer. The mugwort heat-triggered release layer contains mugwort raw materials and / or a carrier of mugwort volatile components; The phase change microcapsule temperature control layer contains phase change microcapsules with a phase change temperature of 42-47°C, and the phase change microcapsules are distributed in a gradient distribution in the thickness direction of the phase change microcapsule temperature control layer, with a high content near the skin side and a low content near the iron powder oxidation heating layer side. The iron powder oxidation heating layer contains an oxidation heating system with iron powder as the heat source; The oxygen-limiting and breathable backing layer is disposed on the side of the iron powder oxidation heating layer away from the skin, and is used to limit the oxygen flux entering the iron powder oxidation heating layer; The ratio of the total latent heat of the phase change microcapsules to the theoretical heat release calculated based on the complete oxidation of iron powder in the iron powder oxidation heating layer to ferric oxide is 0.06 to 0.

18.

2. The constant temperature moxibustion patch according to claim 1, characterized in that, The phase change microcapsule includes a phase change core material and a wall material covering the phase change core material; The phase change core material is paraffin wax, fatty acid ester, fatty alcohol, polyethylene glycol, or a combination thereof; The wall material is melamine-formaldehyde resin, urea-formaldehyde resin, polyurethane, polymethyl methacrylate, silicon dioxide, or a combination thereof; The phase change microcapsules have an average particle size of 5–80 μm and an encapsulation efficiency of 70–95%.

3. The constant temperature moxibustion patch according to claim 1, characterized in that, The phase change microcapsule temperature control layer includes a high phase change content region near the skin and a low phase change content region near the iron powder oxidation heating layer. The mass fraction of phase change microcapsules in the high phase change content region is 35-65%; The mass fraction of phase change microcapsules in the low phase change content region is 15-35%; Furthermore, the mass fraction of phase change microcapsules in the high phase change content region is 1.5 to 3.5 times that in the low phase change content region.

4. The constant temperature moxibustion patch according to claim 1, characterized in that, The phase change microcapsule temperature control layer also includes thermally conductive fillers and elastic, breathable adhesives; The thermally conductive filler is far-infrared ceramic powder, boron nitride, alumina, graphene microplates or a combination thereof, and the mass fraction of the thermally conductive filler in the phase change microcapsule temperature control layer is 3-15%. The elastic and breathable adhesive is medical polyurethane, acrylate pressure-sensitive adhesive, silicone gel, or a combination thereof.

5. The constant temperature moxibustion patch according to claim 1, characterized in that, The iron powder oxidation heating layer comprises, by weight, 45-60 parts iron powder, 4-10 parts activated carbon, 10-25 parts vermiculite, 1.5-5 parts inorganic salt, 10-22 parts water, and 1-5 parts water-absorbing resin. The inorganic salt is sodium chloride, potassium chloride, sodium sulfate, or a combination thereof; The water-absorbing resin is a polyacrylate water-absorbing resin, a starch-grafted water-absorbing resin, a polyvinyl alcohol water-absorbing resin, or a combination thereof.

6. The constant temperature moxibustion patch according to claim 1, characterized in that, The heat-triggered release layer of Artemisia argyi comprises, by mass, 30-70 parts of Artemisia argyi powder or Artemisia argyi floss powder, 3-15 parts of Artemisia argyi volatile oil inclusion complex, and 10-40 parts of breathable film-forming matrix. The volatile oil inclusion complex of Artemisia argyi is an inclusion complex or adsorption complex formed by Artemisia argyi volatile oil and one or more of β-cyclodextrin, hydroxypropyl-β-cyclodextrin, porous starch, and porous silica. The breathable film-forming matrix is ​​hydroxypropyl methylcellulose, gelatin, sodium alginate, polyvinyl alcohol, medical polyurethane, or a combination thereof; The mugwort heat-triggered release layer also includes one or more of the following: 1-8 parts ginger extract, 0.5-5 parts cinnamon extract, and 1-8 parts far-infrared ceramic powder.

7. The constant temperature moxibustion patch according to claim 1, characterized in that, The oxygen-limiting and breathable backing layer is one of microporous polyethylene membrane, microporous polypropylene membrane, polyurethane breathable membrane, and non-woven fabric-microporous membrane composite layer, and the oxygen permeability of the oxygen-limiting and breathable backing layer is 2000~9000cm³ / (m²·24h·0.1MPa). The oxygen-limiting and breathable backing layer is provided with oxygen flux zones, and the oxygen permeability in the central area of ​​the body is lower than that in the edge area of ​​the body. And / or, the patch further includes a release protective layer and an annular positioning adhesive layer, the release protective layer being peelably covered on the side of the mugwort heat-triggered release layer and the annular positioning adhesive layer near the skin, the annular positioning adhesive layer surrounding the outer periphery of the mugwort heat-triggered release layer, so that the central area of ​​the mugwort heat-triggered release layer is opposite to the skin during use and is not covered by pressure-sensitive adhesive; The patch is sealed in an oxygen-barrier outer packaging bag before use. The oxygen-barrier outer packaging bag is an aluminum-plastic composite film bag or an aluminized composite film bag, and the oxygen volume fraction in the oxygen-barrier outer packaging bag is not higher than 2%.

8. A method for preparing a constant-temperature moxibustion patch based on phase change microcapsules-iron powder oxidation synergistic temperature control as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Prepare phase change microcapsules by emulsifying and dispersing the phase change core material in an aqueous system and forming a coating wall material through in-situ polymerization, interfacial polymerization or sol-gel reaction to obtain phase change microcapsules with a phase change temperature of 42-47℃. S2. The phase change microcapsules are prepared into a phase change microcapsule slurry, and a phase change microcapsule temperature control layer with a gradient distribution of phase change microcapsule content in the thickness direction is formed by multiple coating, dual-channel slit coating or layered calendering. S3. Mix the mugwort raw material and / or the mugwort volatile component carrier with the breathable film-forming matrix to form a mugwort heat-triggered release layer; S4. Mix iron powder, activated carbon, vermiculite, inorganic salts, water and water-absorbing resin to form an iron powder oxidation heating layer; S5. The mugwort heat-triggered release layer, the phase change microcapsule temperature control layer, the iron powder oxidation heating layer and the oxygen-limiting breathable backing layer are sequentially composited to obtain the patch.

9. The preparation method according to claim 8, characterized in that, In step S2, a low content of phase change microcapsule slurry is first coated on the side near the iron powder oxidation heating layer, and then a high content of phase change microcapsule slurry is coated on the side near the skin. The solid content of the phase change microcapsules in the low-content phase change microcapsule slurry is 15-35%; The high-content phase change microcapsule slurry has a solid content of 35-65% in the phase change microcapsules. The drying temperature after each coating should not exceed 40℃; And / or, in step S3, the volatile oil of Artemisia argyi is first encapsulated or adsorbed with β-cyclodextrin, hydroxypropyl-β-cyclodextrin, porous starch or porous silica to obtain the volatile oil inclusion complex of Artemisia argyi. Then, the volatile oil inclusion complex of Artemisia argyi is mixed with Artemisia argyi powder or Artemisia argyi powder and a breathable film-forming matrix to form the heat-triggered release layer of Artemisia argyi.

10. The preparation method according to claim 8, characterized in that, In step S4, the moisture content of the iron powder oxidation heating layer is controlled to be 12-24%. After mixing, it is allowed to stand and be balanced for 0.5-4 hours in a nitrogen environment or a low oxygen environment with an oxygen volume fraction of no more than 5% before filling or compounding. And / or, after step S5, the patch is sealed in an oxygen-barrier outer packaging bag.

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