A self-heating medical warming blanket and a preparation method thereof

Abstract

This invention belongs to the technical field of medical thermal insulation equipment, and provides a self-heating medical thermal blanket and its preparation method. The thermal blanket includes a flexible encapsulation body and, sequentially arranged within it, a water storage layer, a fiber transverse water-guiding layer, an independent self-gelling water-controlling layer, a molecular sieve heating layer, and a patient contact layer. The water storage layer has a fixed flow-resistance water outlet and a removable isolation strip covering the water outlet holes and having an exposed pull-out end. After activation, water flows through the flow restriction and spreads along the blanket's plane by the fiber transverse water-guiding layer. The independent self-gelling water-controlling layer includes overlapping calcium sulfate dihydrate spaced calcium source areas and sodium alginate spaced load areas, forming dispersed gel resistance-adjusting areas upon contact with water while retaining open water supply areas. The molecular sieve heating layer contains a partitioned encapsulated activated molecular sieve, and a thermal buffer layer is provided on the patient contact side. This thermal blanket can reduce water flow deviation and provide instantaneous concentrated water supply, improving temperature uniformity under bending, tilting, or localized pressure conditions.

Description

Technical Field

[0001] This invention belongs to the technical field of medical insulation equipment, and relates to a self-heating medical insulation blanket and its preparation method. Background Technology

[0002] Medical warming blankets can be used for patient transport, intraoperative warming, postoperative rewarming, and emergency treatment. Compared to heating devices that require an external power source, self-heating warming blankets using water-triggered inorganic heating materials are easy to carry, convenient to start, and can be used anywhere regardless of power supply conditions. These blankets typically separate and encapsulate the water and inorganic heating material; the separation is removed during use, allowing the water to enter the heating material layer and release heat through adsorption or hydration.

[0003] Flexible medical warming blankets are difficult to maintain a perfectly level and flat state during actual use. Changes in patient positioning, transfer procedures, blanket wrapping, and limb pressure can all cause the blanket to bend, tilt, or experience localized pressure. Once the water reservoir is activated, the water phase is easily affected by gravity, capillary action, and external pressure, causing it to flow along areas of lower resistance. This results in some areas receiving more water, while other areas receive insufficient water. Areas with concentrated water have an increased liquid-to-solid ratio, leading to a faster heating response and concentrated heat release; areas with insufficient water release exhibit weaker heat release, resulting in uneven temperature distribution within the blanket.

[0004] Existing technologies typically employ absorbent fibers, partitioned encapsulation, flow channels, or gel materials to regulate the water transfer process. However, simply increasing absorbency may cause water retention, hindering water from continuing to enter the heating material layer. Simply setting up flow channels may create preferential flow paths under inclined or pressurized conditions. Continuous gel layers may also generate significant water permeability resistance, affecting the normal water supply to the heating material. Therefore, existing structures struggle to simultaneously achieve lateral water phase spread, continuous supply, and localized flow constraints.

[0005] The technical problem to be solved by this application is that when water-triggered inorganic heating materials are used in flexible medical thermal blankets, the water phase after activation is prone to flow deviation during the bending, tilting or local pressure of the blanket, which increases the liquid-solid ratio in some areas and concentrates heat release, resulting in local overheating on the patient contact side. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a self-heating medical insulation blanket and its preparation method, specifically targeting the problem of localized overheating caused by water phase deviation when flexible medical insulation blankets are bent, tilted, or subjected to localized pressure. The insulation blanket incorporates a fixed flow-resistance water outlet, a transverse fiber water-guiding layer, and an independent self-gelling water-controlling layer between the water storage layer and the molecular sieve heating layer. Water supply is controlled collaboratively through flow restriction, transverse spreading, and zoned resistance adjustment. The invention also discloses methods for preparing, aligning, and sealing each functional layer, which can suppress water concentration, ensure uniform heating, and improve safety during use.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a self-heating medical thermal blanket, comprising a flexible encapsulation body and a water storage layer and a molecular sieve heating layer disposed within the flexible encapsulation body.

[0009] Between the water storage layer and the molecular sieve heating layer, a liquid isolation structure, a fiber transverse water-conducting layer, and an independent self-gelling water-controlling layer are sequentially provided from the water storage layer to the molecular sieve heating layer.

[0010] The water storage layer is provided with a fixed flow resistance water outlet on the side facing the fiber transverse water guiding layer. The fixed flow resistance water outlet includes at least two water outlet holes spaced apart along the plane of the blanket body. The diameter of the water outlet holes is 0.5 to 1.5 mm. The liquid isolation structure includes at least one removable isolation strip covering the water outlet holes. Each removable isolation strip covers at least one water outlet hole. One end of the removable isolation strip extends along the plane of the blanket body and protrudes from the flexible encapsulation body to form a pull-out end.

[0011] The fiber transverse water-conducting layer is continuously arranged along the plane of the blanket body;

[0012] The independent self-gelling water-controlling layer includes a first porous carrier, calcium sulfate dihydrate forming a spacer calcium source region on the first porous carrier, a second porous carrier, and sodium alginate forming a spacer load region on the second porous carrier. The spacer calcium source region and the spacer load region have their orthogonal projections in the thickness direction of the blanket coincide. The first porous carrier is located between the fiber transverse water-conducting layer and the second porous carrier.

[0013] The molecular sieve heating layer includes an activated 13X molecular sieve; a patient contact layer is provided on the side of the molecular sieve heating layer opposite to the independent self-gelling water control layer.

[0014] Preferably, the water storage layer includes a closed water storage cavity formed by a flexible water-resistant membrane and water contained in the closed water storage cavity; the water outlets are arranged in two rows at intervals, and each row of water outlets is covered by a PET / PE composite removable isolation strip.

[0015] Preferably, the first porous carrier is a two-component hot-air nonwoven fabric with PE as the outer layer and PET as the core layer, and has an areal density of 20-40 g / m³. 2 The second porous carrier is a spunlace nonwoven fabric formed of viscose fiber and polyester fiber, wherein the mass ratio of viscose fiber to polyester fiber is 50:50, and the areal density is 38-60 g / m³. 2 .

[0016] Preferably, the sodium alginate forms a circular loading region on the second porous carrier. The circular loading regions are arranged in a square array. The diameter of the circular loading region is 2-3 mm. An open region without sodium alginate is provided between adjacent circular loading regions. The orthographic projection of the open region in the thickness direction of the blanket does not overlap with the spacer calcium source region.

[0017] Preferably, the dry loading of sodium alginate on the second porous support is 12–30 g / m², based on the total area of ​​the second porous support. 2 The mass ratio of the calcium sulfate dihydrate to the sodium alginate is 0.25:1 to 0.40:1.

[0018] Preferably, the fiber transverse water-guiding layer comprises at least one of wood pulp air-laid nonwoven fabric, viscose fiber nonwoven fabric, and cellulose absorbent nonwoven fabric, and the areal density of the fiber transverse water-guiding layer is 40-100 g / m³. 2 .

[0019] Preferably, the molecular sieve heating layer includes at least two adjacent molecular sieve accommodating areas; the fiber transverse water guiding layer includes oriented fiber bundles and / or embossed flow guiding channels extending along the plane of the blanket, and the orthogonal projection of the oriented fiber bundles and / or embossed flow guiding channels on the molecular sieve heating layer continuously spans the adjacent molecular sieve accommodating areas.

[0020] Preferably, the activated 13X molecular sieve has a particle size of 0.4–1.2 mm, and the areal density of the activated 13X molecular sieve in the molecular sieve heating layer is 350–700 g / m³. 2 The mass ratio of water in the water storage layer to the activated 13X molecular sieve is 0.18:1 to 0.28:1.

[0021] Preferably, the molecular sieve heating layer includes two layers of water-permeable nonwoven fabric arranged opposite each other and at least two molecular sieve containing areas located between the two layers of water-permeable nonwoven fabric, and heat-sealing separation lines, ultrasonic welding separation lines or sewing separation lines are provided between adjacent molecular sieve containing areas.

[0022] Preferably, the water storage layer is sheet-like and is disposed opposite to the molecular sieve heating layer, and the planar overlap area between the water storage layer and the molecular sieve heating layer is 70% to 100% of the area of ​​the molecular sieve heating layer.

[0023] Preferably, a thermal buffer layer is provided between the molecular sieve heating layer and the patient contact layer. The thermal buffer layer includes fiber flocs and a phase change mixture disposed in the fiber flocs. The phase change mixture is composed of 70% to 80% by mass of n-docosahexanes and 20% to 30% by mass of porous silica. The phase change temperature of the n-docosahexanes is 39-41°C.

[0024] Preferably, the flexible encapsulation body includes a non-metallic moisture-barrier composite film disposed on the outside of the water storage layer and a skin-friendly non-woven fabric constituting the patient contact layer. The non-metallic moisture-barrier composite film is a PA / PE composite film, a PET / PE composite film, or a multilayer co-extruded polyolefin barrier film.

[0025] Secondly, the present invention provides a method for preparing the self-heating medical insulation blanket described in the first aspect, comprising the following steps:

[0026] S1, sodium alginate aqueous solution is coated intermittently onto the second porous support, and after drying, sodium alginate supported support is obtained.

[0027] S2, calcium sulfate dihydrate is distributed in a dry state at intervals on a first porous carrier and fixed by covering with a mesh, forming an interval calcium source region on the first porous carrier, thus obtaining a calcium sulfate dihydrate carrier.

[0028] S3, the calcium sulfate dihydrate carrier and the sodium alginate carrier are aligned and stacked with the carrier edge and corresponding positioning mark as common positioning reference. The orthographic projection of the spaced calcium source area and the spaced load area in the thickness direction of the blanket coincides, and spaced point fixation is performed in the periphery and the area outside the spaced load area to obtain an independent self-gelling water control layer.

[0029] S4, the activated 13X molecular sieve is laid between two layers of water-permeable nonwoven fabric, and the two layers of water-permeable nonwoven fabric are edge-sealed and area-separated to obtain the molecular sieve heating layer.

[0030] S5, water is sealed in a closed water storage cavity formed by a flexible water-blocking membrane, and a fixed flow-blocking water outlet part including a water outlet hole is formed on one side of the closed water storage cavity. At least one removable isolation strip is used to cover the water outlet hole, and one end of each removable isolation strip extends to the edge of the water storage layer to form a pull-out end, thereby obtaining a water storage layer.

[0031] S6, using skin-friendly non-woven fabric as the patient contact layer, and stacking it in the order of the water storage layer, the fiber transverse water guiding layer, the independent self-gelling water control layer, the molecular sieve heating layer and the patient contact layer, wherein the side of the water storage layer with the fixed flow resistance water outlet faces the fiber transverse water guiding layer, and the first porous carrier faces the fiber transverse water guiding layer.

[0032] S7, cover each layer after stacking with a flexible moisture-proof encapsulation film on the side away from the patient contact layer, seal the flexible moisture-proof encapsulation film and the patient contact layer along the periphery, and make the pull-out end of the removable isolation strip extend out of the flexible encapsulation body to form a flexible encapsulation body that accommodates each layer after stacking, and encapsulate the flexible encapsulation body in a flexible moisture-proof package.

[0033] Preferably, the sodium alginate aqueous solution used in S1 has a sodium alginate mass fraction of 1% to 4%, and the coating method is screen printing, stencil coating, gravure coating or dot roll coating; the second porous carrier after coating is dried at 50 to 80°C, and the moisture content after drying is not higher than 8%.

[0034] Preferably, S2 includes: sieving the calcium sulfate dihydrate dry powder; spreading the sieved calcium sulfate dihydrate dry powder at intervals on the first porous carrier to form the interval calcium source area; covering the interval calcium source area with a fixing mesh; connecting the fixing mesh to the first porous carrier by a point fixing method; the point fixing adopts ultrasonic point bonding, hot melt fiber point bonding or hot press point bonding, and the point fixing area is set between adjacent interval calcium source areas.

[0035] Preferably, before S4, the 13X molecular sieve is activated at 250-350°C for 2-6 hours; the activated 13X molecular sieve is cooled in a dry gas environment with a dew point not higher than -20°C and transferred between the two layers of the water-permeable nonwoven fabric, and the dew point of the environment in which the activated 13X molecular sieve is located is kept not higher than -20°C before the periphery of the flexible encapsulation body is sealed.

[0036] When the removable isolation strip covers the water outlet of the water storage layer, there is no liquid phase contact between the water and the fiber transverse water-conducting layer and the molecular sieve heating layer. During use, the removable isolation strip is simultaneously removed from the flexible packaging body, connecting the water outlet to the fiber transverse water-conducting layer. Water from the water storage layer enters the fiber transverse water-conducting layer through the water outlet. The sealed water storage cavity is composed of a flexible water-resistant membrane. During water discharge, it collapses flexibly as the liquid level drops. The negative pressure within the cavity, the flow resistance of the water outlet, and the capillary suction of the fiber transverse water-conducting layer work together to maintain a stable water discharge rate during the start-up phase. The pore size and total opening area of ​​the water outlet limit the amount of water entering the fiber transverse water-conducting layer per unit time during the start-up phase, allowing time for the dissolution of calcium sulfate dihydrate and the ionic cross-linking of sodium alginate. The water outlet serves as a flow constraint, while the removable isolation strip provides liquid isolation during storage.

[0037] After water enters the transverse water-conducting layer of the cellulose fibers, the hydroxyl groups on the fiber surface form hydrogen bonds with water molecules, causing the water to wet the fiber surface. The pores between the fibers form capillary channels, and the capillary pressure generated by the meniscus drives the water to diffuse along the plane of the blanket. The channels formed by the fiber intersections increase the length of the water flow path, causing liquid near the outlet to migrate to the surrounding area. When the blanket is tilted, capillary pressure and channel friction weaken the water migration caused by gravity; under localized pressure, the pores in the pressured area contract, generating a liquid phase pressure difference, and water transfers along the adjacent fiber channels to the unpressured area.

[0038] The calcium source carrier is a two-component hot-air nonwoven fabric with a polyethylene outer layer and a polyester core layer. Hot-air processing melts the polyethylene outer layer at fiber intersections, forming bonding points, while the polyester core layer maintains the fiber skeleton and porous structure. Calcium sulfate dihydrate is distributed between the calcium source carrier and the fixing mesh, with spaced dot-like connections restricting the planar migration of the powder during bending and compression, while retaining channels for water to enter the calcium source area. Polyethylene and polyester are insoluble in water and serve to support and confine the powder during operation, without participating in the alginate crosslinking reaction.

[0039] The sodium alginate carrier is a spunlace nonwoven fabric formed from viscose and polyester fibers. The hydroentangling process causes the fibers to interlock, entangle, and lock together, creating interconnected pores. When the coating solution enters the surface of the viscose fibers and at the fiber intersections, the hydroxyl and carboxylate groups on the sodium alginate chains form hydrogen bonds with the hydroxyl groups on the viscose fiber surface. During drying, moisture leaves the coated area, and the sodium alginate chains deposit on the fiber surface, forming polymer bridging structures between adjacent fibers. The polyester fibers restrict the dimensional changes of the carrier after water absorption, while the viscose fibers provide the interface for sodium alginate adhesion and moisture transfer.

[0040] Upon contact with water, calcium sulfate dihydrate establishes a dissolution equilibrium, releasing calcium and sulfate ions into the aqueous phase. In this scheme, calcium sulfate dihydrate does not act as a water absorber or exothermic agent; its role is to provide calcium ions. Sodium alginate undergoes segmental hydration upon contact with water, allowing sodium ions surrounding the carboxylate groups to enter the aqueous phase, transforming the polymer chains from a coiled state to a hydrated state. Calcium ions diffuse into the sodium alginate loading region and coordinate with the carboxylate oxygen groups on adjacent alginate chains, connecting different polymer segments. Guroguronic acid segments provide coordination sites, and calcium ions embed between segments to form an egg-box coordination structure, transforming water-soluble sodium alginate into a calcium alginate gel with ionic crosslinking points.

[0041] After calcium ions are coordinated by alginate chains, the activity of free calcium ions in the aqueous phase decreases, and the dissolution equilibrium of calcium sulfate dihydrate shifts towards dissolution, allowing the calcium source region to continue releasing calcium ions. This process forms a calcium supply mechanism driven by coordination consumption, preventing abrupt changes in calcium ion concentration when soluble calcium salts come into contact with water. The dissolution of calcium sulfate dihydrate, the diffusion of calcium ions, the hydration of sodium alginate, and interchain coordination occur sequentially. The constraint of the initial water flow by the fixed flow resistance at the outlet section allows the above process to establish flow resistance before a large amount of water penetrates the water-controlling layer.

[0042] The calcium source region and the sodium alginate-loaded region project onto the thickness of the blanket, and the diffusion path of calcium ions points towards the sodium alginate-loaded region. In the open regions without sodium alginate, calcium sulfate dihydrate is not placed at the corresponding locations, preventing water flow from carrying calcium ions around the sodium alginate-loaded region and avoiding ineffective calcium salt migration in the open regions. The loaded region forms a gel resistance-modulating area, while the open regions retain liquid phase channels. This structure prevents water channels from being blocked after a continuous gel film covers the blanket plane.

[0043] When the local influent flow rate increases, the hydration range of sodium alginate expands, increasing the number of chain segments entering the aqueous phase and consequently the number of carboxylate groups that can participate in coordination. The resulting ionic cross-linked network occupies the fiber pores, increasing the tortuosity of the liquid flow path and interfacial friction, leading to a rise in local pressure drop. Subsequent water flow then shifts to other open zones and adjacent channels. When the influent flow rate decreases, the open zones remain interconnected, maintaining water supply without relying on gel permeation. The juxtaposition of the gel zone and the open zone allows the water-controlling layer to simultaneously provide both flow regulation and continuous water supply pathways.

[0044] The gel forms in the fibrous pores and interstices of the sodium alginate support, with the polymer chains constrained by the support through hydrogen bonding, entanglement, and ionic cross-linking. When the blanket is compressed, the support skeleton bears the external force, and water in the pores of the gel region can enter adjacent pores and open regions, and then be redistributed by the transverse water-conducting layer. The open boundaries between discrete gel regions shorten the water migration path, reducing the impact of concentrated water evolution on the heating layer after continuous gel is compressed.

[0045] The activation process removes adsorbed water from the molecular sieve pores, exposing framework cations and adsorption sites on the pore walls. The aluminum-oxygen structure in the molecular sieve framework carries a negative charge, which is compensated for by sodium ions within the pores. When water enters the molecular sieve pores, the dipoles of water molecules interact with sodium ions, forming ionic dipoles, while simultaneously forming hydrogen bonds with framework oxygen. Subsequent water molecules entering the pores continue to form hydrogen-bonded clusters with already adsorbed water molecules, transforming the water from a free liquid phase to an adsorbed state within the pores. This state transition is accompanied by a decrease in enthalpy, and the released energy is transferred as heat to the molecular sieve particles, the water-permeable nonwoven fabric, and the patient contact layer. This exothermic reaction originates from adsorption and hydration and does not involve combustion or redox reactions.

[0046] Molecular sieve particles are encapsulated within separate containment zones, with the dividing lines restricting planar migration of the particles due to bending, tilting, and pressure. Water from the water control layer enters the pores between the particles through a permeable nonwoven fabric, and then enters the molecular sieve pores from the particle surface. The containment zones restrict the concentrated migration of liquid and particles along the blanket plane, ensuring that the water supply position corresponds to the adsorption and heat release position. Before encapsulation, the activated molecular sieve is protected from contact with ambient moisture to reduce the occupancy of adsorption sites by water before use.

[0047] Upon heating, n-docosahexanes in the heat buffer layer transition from a crystalline to a molten state, absorbing the heat released by the molecular sieve. As the temperature decreases, the n-docosahexanes recrystallize and release the latent heat of phase change. The pores of the porous silica exert capillary pressure on the molten n-docosahexanes, and dispersion occurs between the silanol surfaces and the alkanes, confining part of the molten phase within the pores. The remaining molten phase is distributed in the interparticle spaces and retained by the fiber flocs. The capillary confinement within the pores and the floc retention together inhibit liquid phase migration, maintaining the morphological stability of the phase change mixture within the operating temperature range. The phase change mixture thus absorbs heat from the peak heating level and releases the stored heat during the temperature decrease phase, altering the time distribution of heat transfer to the patient contact side.

[0048] Intermittent coating allows sodium alginate to enter the fiber pores only in predetermined areas, and drying creates a loaded structure where the fiber and polymer are bonded. Intermittent spreading and web-coating fixation allow calcium sulfate dihydrate to form a calcium source region corresponding to the sodium alginate loading area. Alignment and stacking determine the direction of calcium ion diffusion and the location of gel formation; point-like fixation restricts slippage between carriers while preventing the formation of closed bonding boundaries. Regional separation of the molecular sieve layer restricts particle migration, periphery sealing prevents liquid from leaving the blanket, and moisture-proof packaging prevents ambient moisture from entering the molecular sieve pores. The spatial correspondence formed during processing directly determines the locations where water supply, cross-linking, and exothermic reactions occur.

[0049] The ingenuity of this scheme does not stem from the individual material properties of calcium sulfate dihydrate, sodium alginate, water-conducting fibers, or molecular sieves, but rather from the structural relationship between fixed flow resistance, planar water conduction, the ion cross-linking region corresponding to the projection, the open water supply region, and the zoned adsorption and exothermic region. Fixed flow resistance suppresses the peak water flow during the initial stage, allowing calcium source dissolution and alginate cross-linking to precede the penetration of large amounts of water; the transverse water-conducting layer of the fibers transforms the water outlet from the pores into planar spreading; the overlapping projections allow calcium ions to form gel flow resistance at the location of sodium alginate; the open region maintains water transfer to the molecular sieve layer; and the molecular sieve containment region restricts the migration of heat source materials and the aqueous phase. This structure connects water flow velocity, diffusion direction, gel location, and exothermic location in series within the water transfer path.

[0050] Without a fixed flow resistance, water may penetrate the water-control layer before gel formation; without lateral water conduction, water will concentrate near the outlet; when the calcium source region and sodium alginate loading region are misaligned, calcium ions will pass through the open region with water, and sodium alginate may also swell and migrate; when sodium alginate is continuously covered, cross-linking will form a flow barrier that penetrates the plane; when the molecular sieve is not partitioned, particles and water will migrate locally under tilt and pressure. This scheme establishes a water supply constraint mechanism for the local liquid-solid ratio change caused by the water phase deviation by corresponding to the spatial and reaction time relationships of each structure. Its technical contribution is reflected in the simultaneous control of the reaction location and the liquid phase transfer path.

[0051] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention limits the instantaneous water output when the water storage layer is activated by fixing the flow resistance water outlet section, thus reducing the impact of water flow on subsequent functional layers; the fiber transverse water-guiding layer utilizes the capillary action of the fiber pores to guide water to spread along the blanket plane, reducing water phase deviation caused by bending, tilting, and local pressure. The overlapping calcium sulfate dihydrate source region and sodium alginate loading region form a dispersed ion-crosslinked gel region upon contact with water, increasing local flow resistance; the unloaded area retains water supply channels, preventing continuous gel layers from blocking water transfer to the molecular sieve heating layer. The partitioned encapsulation structure restricts the migration of molecular sieve particles and liquid on the blanket plane, ensuring that the water supply position corresponds to the heat release position. The heat buffer layer absorbs heat during the heat release process and releases it when the temperature drops, reducing temperature fluctuations on the patient contact side. Each functional layer maintains a spatial correspondence through aligned stacking and fixed spacing, reducing the probability of increased local liquid-to-solid ratio and concentrated heat release when the blanket is bent, tilted, or under pressure, thus improving heat distribution and safety. Detailed Implementation

[0052] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0053] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0054] The PE / PET bicomponent hot-air nonwoven fabric is a PE sheath / PET core bicomponent hot-air nonwoven fabric produced by Changzhou Youheng Nonwoven Fabric Co., Ltd., with a basis weight of 20-40 g / m². 2 The viscose / polyester spunlace nonwoven fabric is supplied by Foshan Kaiduan Textile Co., Ltd., with a viscose fiber to polyester fiber mass ratio of 50:50 and a basis weight of 38-60 g / m². 2 .

[0055] Sodium alginate, calcium sulfate dihydrate, wood pulp air-laid nonwoven fabric, activated 13X molecular sieve, n-docosahexadecane, porous silica, and fiber flocs are all commercially available industrial products; flexible water-blocking membrane, water-permeable nonwoven fabric, fixing mesh, PA / PE composite film, PET / PE composite film, multilayer co-extruded polyolefin barrier film, skin-friendly nonwoven fabric, and flexible moisture-proof packaging film are all commercially available industrial products.

[0056] Example 1

[0057] This embodiment provides a method for preparing a self-heating medical thermal blanket, the method specifically including the following steps:

[0058] S1, add 7.2g of sodium alginate to 712.8g of deionized water, stir until the sodium alginate dissolves, and let stand to remove bubbles to obtain an aqueous solution of sodium alginate with a solid content of 1wt.%; select a weight of 50g / m 2 A viscose / polyester spunlace nonwoven fabric was used as the second porous carrier, with a viscose fiber to polyester fiber mass ratio of 50:50. A commercially available dot-coating machine was used to coat the second porous carrier with sodium alginate aqueous solution in six coats, with surface drying after each coat. The coating area consisted of circular loading zones with a diameter of 2.0 mm, arranged in a square array with a center-to-center distance of 2.5 mm. After coating, the substrate was dried at 80℃ to obtain a moisture content of 8 wt.% and a dry sodium alginate loading of 12 g / m³. 2 Sodium alginate support;

[0059] S2, with a weight of 20g / m³ 2 A two-component hot-air nonwoven fabric with PE as the outer layer and PET as the core layer was used as the first porous carrier. Calcium sulfate dihydrate powder was passed through a 75μm sieve, and 2.88g of the sieve undersize was weighed and spaced onto the first porous carrier using a powder spreading roller, forming spaced calcium source zones with the same size and arrangement as the circular loading zone. A layer with a basis weight of 10g / m² was then placed on top of the calcium sulfate dihydrate. 2 The PE fixing net was ultrasonically spot-bonded in the area where calcium sulfate dihydrate was not sprinkled to obtain a calcium sulfate dihydrate carrier; the mass ratio of calcium sulfate dihydrate to sodium alginate was 0.40:1.

[0060] S3, using the edges and alignment marks of the two carriers as a reference, the calcium sulfate dihydrate carrier and the sodium alginate carrier are aligned and stacked so that the projection of the spacer calcium source area and the circular load area in the thickness direction of the blanket coincides, and the projection of the open area does not overlap with the spacer calcium source area; when stacking, the powder-free surface of the first porous carrier faces outward, and the sodium alginate load surface faces the calcium sulfate dihydrate. Spacer connection points are set along the periphery and the open area to obtain an independent self-gelling water control layer;

[0061] S4, Activate 13X molecular sieve at 350℃ for 2 hours; Cool the activated 13X molecular sieve in dry air with a dew point of -20℃; Lay it on two layers with a basis weight of 25g / m². 2 The surface density of the permeable nonwoven fabric is 350g / m². 2 The actual amount used is 210g; a square molecular sieve containing area with a side length of 50mm is formed by heat sealing, and heat sealing separation lines are set between adjacent containing areas to obtain the molecular sieve heating layer;

[0062] S5, a sealed water storage cavity with a length of 1000mm and a width of 420mm is formed by heat sealing with a PA / PE composite membrane. The planar overlap area between the water storage layer and the molecular sieve heating layer is 70% of the area of ​​the molecular sieve heating layer. 58.8g of deionized water is filled into the sealed water storage cavity and the filling port is sealed. Eight water outlet holes with a diameter of 0.5mm are set on the side of the water storage cavity facing the transverse water guiding layer of the fiber. The water outlet holes are arranged in two rows at intervals, with a total opening area of ​​1.57mm². 2 Two PET / PE composite removable isolation strips are used to cover the two rows of water outlets respectively, with one end of each removable isolation strip extending to the edge of the water storage layer to form a pull-out end;

[0063] S6, with a weight of 70g / m³ 2 Wood pulp airflow formed nonwoven fabric is used as the transverse water-guiding layer of the fibers. Its surface has embossed guiding channels extending along the length of the blanket, and the embossed guiding channels cross adjacent molecular sieve accommodating regions; n-dodecane is melted and mixed with porous silica at a mass ratio of 70:30 to obtain a phase change mixture; the phase change mixture is prepared at 70 g / m 2 The areal density is dispersed in an area with an areal density of 30 g / m 2 In the fiber flocs, an areal density of 100 g / m² was obtained. 2 A thermal buffer layer with a surface density of 60 g / m³ was selected. 2 The skin-friendly spunlace nonwoven fabric is used as the patient contact layer, and is stacked in the following order: water storage layer, fiber transverse water-conducting layer, independent self-gelling water-controlling layer, molecular sieve heating layer, thermal buffer layer and patient contact layer, wherein the first porous carrier faces the fiber transverse water-conducting layer.

[0064] S7, S3, S4, S6 and peripheral sealing are completed in a dry air environment with a dew point of -20℃. The time from cooling to peripheral sealing of the activated 13X molecular sieve is 60 minutes. A PET / PE composite moisture barrier membrane is set on the outside of the water storage layer, and the patient contact layer is coated with a basis weight of 60g / m². 2 The skin-friendly spunlace nonwoven fabric is heat-sealed along the perimeter of the blanket, then placed into a flexible moisture-proof packaging bag and sealed. When the perimeter is sealed, the pull-out ends of the two removable isolation strips extend out of the flexible packaging body.

[0065] Example 2

[0066] This embodiment provides a method for preparing a self-heating medical thermal blanket, the method specifically including the following steps:

[0067] S1, 10.8g of sodium alginate was added to 529.2g of deionized water, stirred to dissolve, and allowed to stand to remove bubbles, yielding an aqueous solution of sodium alginate with a solid content of 2wt.%; a weight of 38g / m³ was selected. 2A spunlace nonwoven fabric with a viscose fiber to polyester fiber mass ratio of 50:50 was used as the second porous carrier. The coating was applied in three stages using a dot-matrix roller coating method, with surface drying after each stage. The diameter of the circular loading zones was 2.4 mm, arranged in a square array with a center-to-center distance of 3.0 mm. After coating, the fabric was dried at 65℃ to obtain a moisture content of 6 wt.% and a dry sodium alginate loading of 18 g / m³. 2 Sodium alginate support;

[0068] S2, with a weight of 32 g / m² 2 A two-component hot-air nonwoven fabric with PE as the outer layer and PET as the core layer was used as the first porous carrier. Calcium sulfate dihydrate dry powder was passed through a 75μm sieve, and 3.24g of the sieve-filled material was weighed and sprinkled on the first porous carrier at intervals according to the size and arrangement of the circular loading area. After covering with a PE fixing mesh, hot-pressing was performed on the areas where no powder was sprinkled to obtain the calcium sulfate dihydrate carrier. The mass ratio of calcium sulfate dihydrate to sodium alginate was 0.30:1.

[0069] S3, calcium sulfate dihydrate carrier and sodium alginate carrier are aligned and stacked according to edge markings so that the projection of the spaced calcium source area coincides with the projection of the circular load area, and the projection of the open area does not overlap with the spaced calcium source area; the two carriers are fixed by peripheral point adhesion and open area spaced point adhesion to obtain an independent self-gelling water control layer.

[0070] S4. Activate the 13X molecular sieve at 300℃ for 4 hours and cool it in dry air with a dew point of -30℃; then lay the activated 13X molecular sieve between two layers of permeable nonwoven fabric with a layup density of 480 g / m². 2 The actual amount used is 288g; a molecular sieve containing area with a length of 60mm and a width of 50mm is formed by ultrasonic welding to obtain the molecular sieve heating layer;

[0071] S5, a sealed water storage cavity with a length of 1000mm and a width of 510mm is formed using a PET / PE composite film. The planar overlap area between the water storage layer and the molecular sieve heating layer is 85% of the area of ​​the molecular sieve heating layer. 51.8g of deionized water is filled into the sealed water storage cavity. Eight water outlet holes with a diameter of 1.0mm are set on the side of the water storage cavity facing the transverse water guiding layer of the fiber. The water outlet holes are arranged in two rows at intervals, with a total opening area of ​​6.28mm². 2 Two PET / PE composite removable isolation strips are used to cover the two rows of water outlets respectively, with one end of each removable isolation strip extending to the edge of the water storage layer to form a pull-out end;

[0072] S6, with a weight of 100g / m³ 2A cellulose-based absorbent nonwoven fabric is used as the transverse water-guiding layer, in which oriented fiber bundles extend along the length of the blanket and cross adjacent molecular sieve containment areas; n-docosahexanes and porous silica are mixed at a mass ratio of 73:27 to form a phase change mixture; the phase change mixture is prepared at a concentration of 70 g / m 2 The areal density is dispersed in an area with an areal density of 30 g / m 2 In the fiber flocs, an areal density of 100 g / m² was obtained. 2 A thermal buffer layer with a surface density of 60 g / m³ was selected. 2 The skin-friendly spunlace nonwoven fabric is used as the patient contact layer, and a water storage layer, a fiber transverse water-conducting layer, an independent self-gelling water control layer, a molecular sieve heating layer, a heat buffer layer, and a patient contact layer are stacked in sequence.

[0073] S7, S3, S4, S6 and perimeter sealing are completed in a dry air environment with a dew point of -30℃. The time from the completion of cooling of the activated 13X molecular sieve to the completion of perimeter sealing is 45 minutes. A PA / PE composite moisture barrier membrane is set on the outside of the water storage layer, and the patient contact layer is covered with skin-friendly spunlace nonwoven fabric. After perimeter heat sealing is completed, it is put into a flexible moisture barrier packaging bag. When perimeter sealing is performed, the pull-out ends of the two removable isolation strips extend out of the flexible package.

[0074] Example 3

[0075] This embodiment provides a method for preparing a self-heating medical thermal blanket, the method specifically including the following steps:

[0076] S1, 14.4g of sodium alginate was added to 345.6g of deionized water, stirred to dissolve and defoamed, to obtain an aqueous solution of sodium alginate with a solid content of 4wt.%; a weight of 60g / m³ was selected. 2 A spunlace nonwoven fabric with a viscose fiber to polyester fiber mass ratio of 50:50 was used as the second porous carrier. A two-stage coating process was employed, using a dotted roller coating method. The diameter of the circular loading areas was 2.7 mm, arranged in a square array with a center-to-center distance of 3.4 mm. After coating, the fabric was dried at 50℃ to obtain a moisture content of 5 wt.% and a sodium alginate dry loading of 24 g / m³. 2 Sodium alginate support;

[0077] S2, with a weight of 40g / m³ 2 A two-component hot-air nonwoven fabric with PE as the outer layer and PET as the core layer was used as the first porous carrier; calcium sulfate dihydrate dry powder was passed through a 75μm sieve, and 3.60g of the sieve material was weighed out and used to form a spaced calcium source area corresponding to the circular loading area using a powder spreading roller; after covering with a fixing net, the fixing net and the first porous carrier were connected by ultrasonic point bonding; the mass ratio of calcium sulfate dihydrate to sodium alginate was 0.25:1.

[0078] S3, according to the alignment marks on the edge of the carrier, stack the calcium sulfate dihydrate support carrier and the sodium alginate support carrier, so that the projection of the spaced calcium source area and the circular load area in the thickness direction coincides, and the projection of the open area does not overlap with the spaced calcium source area; perform spaced point adhesion along the periphery of the two carriers and the open area to obtain an independent self-gelling water control layer.

[0079] S4. Activate the 13X molecular sieve at 250℃ for 6 hours and cool it in dry air with a dew point of -35℃; then lay the activated 13X molecular sieve between two layers of permeable nonwoven fabric with a layup density of 700 g / m². 2 The actual amount used is 420g; a square molecular sieve containing area with a side length of 40mm is formed by using heat-sealing dividing lines to obtain the molecular sieve heating layer;

[0080] S5, a sealed water storage cavity with a length of 1000mm and a width of 600mm is formed by using a multi-layer co-extruded polyolefin water-blocking membrane. The water storage layer and the molecular sieve heating layer have the same planar overlap area. 92.4g of deionized water is filled into the sealed water storage cavity. Eight water outlet holes with a diameter of 1.5mm are set on the side of the water storage cavity facing the transverse water-conducting layer of the fiber. The water outlet holes are arranged in two rows at intervals, with a total opening area of ​​14.14mm². 2 Two PET / PE composite removable isolation strips are used to cover the two rows of water outlets respectively, with one end of each removable isolation strip extending to the edge of the water storage layer to form a pull-out end;

[0081] S6, with a weight of 40g / m³ 2 Viscose fiber nonwoven fabric is used as the transverse water-guiding layer, and continuous water-guiding channels extending along the length of the blanket are pressed on its surface; n-eicosane and porous silica are prepared into a phase change mixture at a mass ratio of 77:23; the phase change mixture is prepared at 70 g / m 2 The areal density is dispersed in an area with an areal density of 30 g / m 2 In the fiber flocs, an areal density of 100 g / m² was obtained. 2 A thermal buffer layer with a surface density of 60 g / m³ was selected. 2 The skin-friendly spunlace nonwoven fabric is used as the patient contact layer, and a water storage layer, a fiber transverse water-conducting layer, an independent self-gelling water control layer, a molecular sieve heating layer, a heat buffer layer, and a patient contact layer are stacked in sequence.

[0082] S7, S3, S4, S6 and peripheral sealing are completed in a dry air environment with a dew point of -35℃. The time from the completion of cooling of the activated 13X molecular sieve to the completion of peripheral sealing is 35 minutes. A multi-layer co-extruded polyolefin barrier film is set on the outside of the water storage layer, and the patient contact layer is covered with skin-friendly spunlace nonwoven fabric. After sealing, it is put into a flexible moisture-proof packaging bag. When sealing the perimeter, the pull-out ends of the two removable isolation strips extend out of the flexible package.

[0083] Example 4

[0084] This embodiment provides a method for preparing a self-heating medical thermal blanket, the method specifically including the following steps:

[0085] S1, 18g of sodium alginate was added to 582g of deionized water, stirred to dissolve and defoamed, to obtain an aqueous solution of sodium alginate with a solid content of 3wt.%; a weight of 45g / m³ was selected. 2 A spunlace nonwoven fabric with a viscose fiber to polyester fiber mass ratio of 50:50 was used as the second porous carrier. A three-stage dot-coating method was employed, with circular loading zones of 3.0 mm in diameter arranged in a square array with a center-to-center distance of 3.8 mm. After coating, the fabric was dried at 70℃ to obtain a moisture content of 7 wt.% and a sodium alginate dry loading of 30 g / m³. 2 Sodium alginate support;

[0086] S2, with a weight of 26 g / m³ 2 A two-component hot-air nonwoven fabric with PE as the outer layer and PET as the core layer was used as the first porous carrier; calcium sulfate dihydrate dry powder was passed through a 75μm sieve, and 6.30g of the sieve material was weighed out and used to form an intermittent calcium source area corresponding to the circular loading area using a powder spreading roller; after covering with a fixing mesh, the powder was fixed by hot-melt fiber spot bonding; the mass ratio of calcium sulfate dihydrate to sodium alginate was 0.35:1.

[0087] S3, the calcium sulfate dihydrate carrier and the sodium alginate carrier are aligned and stacked according to the edge reference line, so that the projection of the spaced calcium source area coincides with the projection of the circular load area, and the projection of the open area does not overlap with the spaced calcium source area; spaced connection points are set along the perimeter and the open area to obtain an independent self-gelling water control layer.

[0088] S4. Activate the 13X molecular sieve at 320℃ for 3.5h and cool it in dry air with a dew point of -25℃; then lay the activated 13X molecular sieve between two layers of permeable nonwoven fabric with a layup surface density of 590g / m². 2 The actual amount used is 354g; a molecular sieve containing area with a length of 50mm and a width of 40mm is formed by ultrasonic welding to obtain the molecular sieve heating layer;

[0089] S5, a closed water storage cavity with a length of 1000mm and a width of 540mm is formed using a PA / PE composite membrane. The planar overlap area between the water storage layer and the molecular sieve heating layer is 90% of the area of ​​the molecular sieve heating layer. 88.5g of deionized water is filled into the closed water storage cavity. Sixteen water outlet holes with a diameter of 0.8mm are set on the side of the water storage cavity facing the transverse water guiding layer of the fiber. The water outlet holes are arranged in two rows at intervals, with a total opening area of ​​8.04mm². 2Two PET / PE composite removable isolation strips are used to cover the two rows of water outlets respectively, with one end of each removable isolation strip extending to the edge of the water storage layer to form a pull-out end;

[0090] S6, with a weight of 85g / m³ 2 A cellulose-based absorbent nonwoven fabric is used as the transverse water-guiding layer, in which oriented fiber bundles extend along the length of the blanket, and embossed water-guiding channels with the same orientation direction are provided on its surface; n-docosane and porous silica are prepared into a phase change mixture at a mass ratio of 80:20; the phase change mixture is prepared at 70 g / m 2 The areal density is dispersed in an area with an areal density of 30 g / m 2 In the fiber flocs, an areal density of 100 g / m² was obtained. 2 A thermal buffer layer with a surface density of 60 g / m³ was selected. 2 The skin-friendly spunlace nonwoven fabric is used as the patient contact layer, and a water storage layer, a fiber transverse water-conducting layer, an independent self-gelling water control layer, a molecular sieve heating layer, a heat buffer layer, and a patient contact layer are stacked in sequence.

[0091] S7, S3, S4, S6 and perimeter sealing are completed in a dry air environment with a dew point of -25℃. The time from the completion of cooling of the activated 13X molecular sieve to the completion of perimeter sealing is 50 minutes. A PET / PE composite moisture barrier membrane is set on the outside of the water storage layer, and the patient contact layer is covered with skin-friendly spunlace nonwoven fabric. After perimeter sealing is completed, it is put into a flexible moisture barrier packaging bag and sealed. When perimeter sealing is performed, the pull-out ends of the two removable isolation strips extend out of the flexible package.

[0092] Comparative Example 1

[0093] This comparative example provides a method for preparing a self-heating medical thermal blanket. The difference from Example 1 is that the eight water outlets with a diameter of 0.5 mm on the water storage layer are replaced with eight water outlets with a diameter of 3.0 mm. The arrangement of the water outlets and the liquid isolation structure remain unchanged. Other process parameters and operating conditions are exactly the same as in Example 1.

[0094] Comparative Example 2

[0095] This comparative example provides a method for preparing a self-heating medical thermal blanket. The difference from Example 1 is that the transverse water-guiding layer of the fiber uses wood pulp air-laid nonwoven fabric with the same basis weight as in Example 1 but without embossed flow channels. Other process parameters and operating conditions are exactly the same as in Example 1.

[0096] Comparative Example 3

[0097] This comparative example provides a method for preparing a self-heating medical thermal blanket. The difference from Example 1 is that calcium sulfate dihydrate is not placed on the first porous carrier, and sodium alginate is not coated on the second porous carrier. The first and second porous carriers are simply stacked in the manner of Example 1. Other process parameters and operating conditions are exactly the same as in Example 1.

[0098] Comparative Example 4

[0099] This comparative example provides a method for preparing a self-heating medical thermal blanket. The difference from Example 1 is that calcium sulfate dihydrate is evenly spread on the entire surface of the first porous carrier, without forming an interstitial calcium source region that coincides with the projection of the sodium alginate circular loading area. The total amount of calcium sulfate dihydrate remains unchanged, and other process parameters and operating conditions are exactly the same as in Example 1.

[0100] Comparative Example 5

[0101] This comparative example provides a method for preparing a self-heating medical thermal blanket. The difference from Example 1 is that sodium alginate is continuously coated on the entire surface of the second porous carrier, and calcium sulfate dihydrate is uniformly sprinkled on the entire surface of the first porous carrier without leaving any open areas. The total amount of sodium alginate and calcium sulfate dihydrate remains unchanged, and other process parameters and operating conditions are exactly the same as in Example 1.

[0102] Test method:

[0103] All examples and comparative samples were placed in an environment of 23±2℃ and 50±5% relative humidity for 24 hours while still in their flexible moisture-proof packaging. The flexible moisture-proof packaging was removed before testing, and the corresponding tests were conducted immediately. Three samples were tested in each group, and the results were taken as the arithmetic mean. New samples were used for different test items, and the same insulation blanket was not used repeatedly.

[0104] I. Water outflow rate test of the reservoir:

[0105] Take an independent water storage layer made using the same process as the insulation blanket to be tested, and place it horizontally on a perforated plastic support plate with the water outlet facing downwards. Place a collection cup below the water outlet. Place the collection cup on an electronic balance with a graduation of 0.01g and zero the electronic balance reading.

[0106] Simultaneously, two removable isolation strips are pulled out and a stopwatch is started. Water from the storage layer flows into the collection cup through the outlet. After 60 seconds, the outflow mass (m) displayed on the electronic balance is read. 60 .

[0107] The average water output rate 60 seconds after startup is calculated using the following formula:

[0108] Q 60 =m 60 / 1min

[0109] In the formula, q 60 The average outflow rate within 60 seconds after startup is given, in g / min.

[0110] II. Molecular sieve heating layer water distribution uniformity test

[0111] During the preparation of the molecular sieve heating layer, 15 molecular sieve-containing areas were selected as detection zones at 5 locations along the length and 3 locations along the width, covering the four corners, edges, center, and core. When 13X molecular sieves were loaded into each detection zone, the dry mass M of the 13X molecular sieves in each detection zone was recorded. i After the area is sealed off, the total dry mass m of each testing area is weighed. 0i Weighing was performed using an electronic balance with a graduation of 0.01g.

[0112] Place the insulation blanket horizontally and simultaneously remove two removable insulating strips. After 10 minutes of operation, remove the insulation blanket from its perimeter and cut out 15 pre-marked testing zones along the dividing lines. Immediately place the cut testing zones into self-sealing bags and weigh them within 3 minutes to obtain the total mass m of each testing zone after water absorption. 1i .

[0113] The mass of water entering the molecular sieve heating layer in each testing area is calculated using the following formula:

[0114] W i =m 1i -m 0i

[0115] The water sieve mass ratio of each testing area is calculated using the following formula:

[0116] R i =W i / M i

[0117] Calculate the coefficient of variation of the water-screen mass ratio for the 15 testing areas. Where:

[0118]

[0119] In the formula, The average water-to-sieve mass ratio is given by s, which is its standard deviation. The test results are expressed as the coefficient of variation (CV) of the water-to-sieve mass ratio, representing the water distribution uniformity, in percentages (%).

[0120] III. Temperature Uniformity Test on the Patient Contact Side

[0121] Lay the thermal blanket flat on a 30mm thick rigid polyurethane foam board, with the water-retaining layer facing down and the patient contact layer facing up. Allow the thermal blanket to unfold naturally without applying external pressure.

[0122] The infrared thermal imager should be positioned directly above the patient's contact layer, with the lens perpendicular to the surface of the insulation blanket and 1.0m away from the patient's contact layer. The emissivity should be set to 0.95. The temperature measurement range of the infrared thermal imager should cover 20–60℃, with a measurement accuracy of no less than ±0.5℃.

[0123] At the same time, two removable isolation strips were extracted, and infrared thermal images were taken before startup and at 1 min, 3 min, 5 min, 10 min, 20 min, 30 min, 45 min and 60 min after startup.

[0124] Remove the area within 50mm of the perimeter of the insulation blanket. Divide the remaining area into 5 columns along the length and 3 rows along the width, forming 15 equal-area temperature measurement zones. Record the average temperature of each zone and take the highest value T among the 15 average temperatures at each test time. max and minimum value T min The temperature range is calculated using the following formula:

[0125] ΔT=T max -T min

[0126] The maximum value among all temperature ranges obtained at all test times is taken as the maximum temperature range ΔTmax on the patient's contact side, in °C.

[0127] IV. Local overheating performance test under bending, tilting and localized pressure conditions

[0128] New thermal blanket samples were used for tilting, bending, and localized pressure conditions, with three samples tested for each condition. Temperature measurements were taken at 5, 10, 20, 30, 45, and 60 minutes after startup.

[0129] During the tilt test, the thermal blanket was fixed to a support plate at a 30° angle to the horizontal plane, with the length of the blanket aligned with the tilt direction and the patient contact layer facing upwards. The infrared thermal imager lens was perpendicular to the patient contact layer, at a distance of 1.0m, and the emissivity was set to 0.95. Infrared thermal images were captured at each test moment, and the highest local temperature on the patient contact side was recorded.

[0130] During the bending test, the insulation blanket was wrapped around a cylindrical support with a radius of 50mm along its width, forming a 90° bend, with the patient contact layer located on the outside of the bend. The infrared thermal imager lens was pointed towards the bisector of the bend area, at a distance of 1.0m from the bend area. Infrared thermal images were captured at each test moment, and the highest local temperature on the patient contact side was recorded.

[0131] During the localized pressure test, a K-type thermocouple with a wire diameter not exceeding 0.20 mm is fixed to the center of the patient contact layer before the test, with the measuring end in contact with the patient contact layer surface. A 100 mm × 100 mm PTFE pressure plate is placed above the measuring end, and weights are loaded onto the pressure plate, making the total mass of the pressure plate and weights 5.1 kg, applying a pressure of approximately 5.0 kPa to the patient contact layer. Simultaneously, two removable isolation strips are removed, and a digital thermometer is used to read the temperature of the pressure area at each test moment. The pressure plate and weights are not moved during the test.

[0132] The highest temperatures under tilted, bent, and locally compressed conditions were obtained respectively, and the maximum value among the three was taken as the local maximum temperature T under complex usage conditions. complex This test only records T. complex The unit is ℃.

[0133] The test results are shown in Table 1.

[0134] Table 1. Test results of self-heating medical blankets in Examples 1-4 and Comparative Examples 1-5

[0135]

[0136] As shown in Table 1, compared with Example 1, the average water flow rate, water distribution coefficient of variation, maximum temperature range on the patient contact side, and local maximum temperature under complex usage conditions all increased in Comparative Example 1; the average water flow rate, water distribution coefficient of variation, maximum temperature range on the patient contact side, and local maximum temperature under complex usage conditions all increased in Comparative Example 2; the average water flow rate, water distribution coefficient of variation, maximum temperature range on the patient contact side, and local maximum temperature under complex usage conditions remained unchanged in Comparative Example 3, but the water distribution coefficient of variation, maximum temperature range on the patient contact side, and local maximum temperature under complex usage conditions all increased in Comparative Example 4; the average water flow rate, water distribution coefficient of variation, maximum temperature range on the patient contact side, and local maximum temperature under complex usage conditions all increased in Comparative Example 5; and the average water flow rate, water distribution coefficient of variation, maximum temperature range on the patient contact side, and local maximum temperature under complex usage conditions all increased in Comparative Example 5.

[0137] This is because, in Comparative Example 1, the pore size of the water outlet holes in the water storage layer was increased, resulting in a larger total opening area. Simultaneously, after removing the two removable isolation strips, the water in the water storage layer flowed out in a concentrated manner during the startup phase. The amount of water entering the transverse water-conducting layer of the fiber exceeded the speed at which the fiber pores spread along the blanket plane, and some water directly entered the independent self-gelling water-controlling layer along the thickness direction below the water outlet holes. Before the dissolution of calcium sulfate dihydrate, the diffusion of calcium ions, and the hydration and cross-linking of sodium alginate formed flow resistance, water had already entered the molecular sieve containing area at the corresponding location, causing a widening difference in the water-sieve mass ratio between different areas. The molecular sieve containing area, which obtained a larger amount of water, completed adsorption and heat release in a short time, leading to an increase in the maximum temperature difference on the patient contact side and the highest local temperature under complex usage conditions.

[0138] Comparative Example 2 used a wood pulp air-laid nonwoven fabric without embossed flow channels. The material composition and areal density of this nonwoven fabric were the same as in Example 1, but its fiber channels did not form a continuous flow path along the blanket plane through embossing. Water released from the water storage layer was mainly transferred to the molecular sieve heating layer along the pores below and near the water outlet, resulting in reduced spread on the blanket plane before entering the independent self-gelling water control layer. When bent, tilted, or under localized pressure, water further migrated along the direction of gravity or into localized low-resistivity areas, leading to an increase in the water distribution variation coefficient, the maximum temperature difference on the patient contact side, and the highest local temperature under complex usage conditions.

[0139] Comparative Example 3 did not have calcium sulfate dihydrate on the first porous carrier, nor sodium alginate coated on the second porous carrier. After water spreads through the transverse water-conducting layer of the fiber, it only passes through the two porous carrier layers before entering the molecular sieve heating layer, without calcium sulfate dihydrate dissolution, calcium ion diffusion, or sodium alginate ion cross-linking. When the local water flow rate increases, the pore structure of the porous carrier cannot form a corresponding flow resistance with the change in water flow, and the water continues to enter the molecular sieve containment area along the original low-resistance path. During the bending, tilting, or local pressure of the blanket, the already formed deflection cannot be constrained by the increased flow resistance in the gel area, leading to an increase in the coefficient of variation of water distribution and causing an increase in the maximum temperature difference on the patient contact side and the highest local temperature under complex usage conditions.

[0140] In Comparative Example 4, calcium sulfate dihydrate was uniformly distributed across the entire surface of the first porous carrier, without forming a spaced calcium source region that coincided with the projection of the sodium alginate circular loading area. When water passed through the first porous carrier, calcium ions dissolved in all regions. Calcium ions located in the corresponding positions of the sodium alginate circular loading area participated in cross-linking, while calcium ions located in the corresponding positions of the open areas passed through the second porous carrier with the water and entered the molecular sieve heating layer. The open areas did not form gel flow resistance and still constituted the preferred path for water flow; the diffusion distance of calcium ions and the degree of sodium alginate cross-linking also varied at different locations. The lack of a spatial correspondence between the calcium source positions and the sodium alginate loading positions resulted in a mismatch between the gel resistance adjustment area and the actual water flow path, thus increasing the coefficient of variation of water distribution, the maximum temperature difference on the patient contact side, and the local maximum temperature under complex usage conditions.

[0141] In Comparative Example 5, sodium alginate was continuously coated onto the entire surface of a second porous carrier, while calcium sulfate dihydrate was uniformly sprinkled onto the entire surface of a first porous carrier. After water entered between the two carriers, calcium ions cross-linked with the continuously distributed sodium alginate, forming a continuous gel layer on the blanket plane. This continuous gel layer occupies the interconnected pores of the second porous carrier, increasing the resistance to water transmission along the thickness direction and causing water to accumulate upstream of the gel layer. Differences in flow resistance caused by coating thickness, powder distribution, and localized pressure cause accumulated water to preferentially penetrate from areas of lower resistance, forming localized water supply channels. Because no open water supply area was maintained, water could not continuously enter the molecular sieve heating layer through the pre-set channels. Instead, it concentrated in the corresponding molecular sieve containment area after localized breakthroughs, leading to an increase in the coefficient of variation of water distribution, the maximum temperature difference on the patient contact side, and the highest local temperature under complex usage conditions.

[0142] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A self-heating medical thermal blanket, comprising a flexible encapsulation body and a water storage layer and a molecular sieve heating layer disposed within the flexible encapsulation body, characterized in that, Between the water storage layer and the molecular sieve heating layer, a liquid isolation structure, a fiber transverse water-conducting layer, and an independent self-gelling water-controlling layer are sequentially provided from the water storage layer to the molecular sieve heating layer. The water storage layer is provided with a fixed flow resistance water outlet on the side facing the fiber transverse water guiding layer. The fixed flow resistance water outlet includes at least two water outlet holes spaced apart along the plane of the blanket body. The diameter of the water outlet holes is 0.5 to 1.5 mm. The liquid isolation structure includes at least one removable isolation strip covering the water outlet holes. Each removable isolation strip covers at least one water outlet hole. One end of the removable isolation strip extends along the plane of the blanket body and protrudes from the flexible encapsulation body to form a pull-out end. The fiber transverse water-conducting layer is continuously arranged along the plane of the blanket body; The independent self-gelling water-controlling layer includes a first porous carrier, calcium sulfate dihydrate forming a spacer calcium source region on the first porous carrier, a second porous carrier, and sodium alginate forming a spacer load region on the second porous carrier. The spacer calcium source region and the spacer load region have their orthogonal projections in the thickness direction of the blanket coincide. The first porous carrier is located between the fiber transverse water-conducting layer and the second porous carrier. The molecular sieve heating layer includes an activated 13X molecular sieve; a patient contact layer is provided on the side of the molecular sieve heating layer opposite to the independent self-gelling water control layer.

2. The self-heating medical thermal blanket according to claim 1, characterized in that, The water storage layer includes a sealed water storage cavity formed by a flexible water-resistant membrane and water contained in the sealed water storage cavity; the water outlets are arranged in two rows at intervals, and each row of water outlets is covered by a PET / PE composite removable isolation strip.

3. The self-heating medical thermal blanket according to claim 1, characterized in that: The first porous carrier is a two-component hot-air nonwoven fabric with PE as the outer layer and PET as the core layer, and has an areal density of 20-40 g / m³. 2 The second porous carrier is a spunlace nonwoven fabric formed of viscose fiber and polyester fiber, wherein the mass ratio of viscose fiber to polyester fiber is 50:50, and the areal density is 38-60 g / m³. 2 .

4. The self-heating medical insulation blanket according to claim 3, characterized in that: The sodium alginate forms a circular loading region on the second porous carrier. The circular loading regions are arranged in a square array. The diameter of the circular loading region is 2-3 mm. An open region without sodium alginate is set between adjacent circular loading regions. The orthographic projection of the open region in the thickness direction of the blanket does not overlap with the spacer calcium source region.

5. The self-heating medical insulation blanket according to claim 3, characterized in that: Based on the total area of ​​the second porous support, the dry loading of sodium alginate on the second porous support is 12-30 g / m². 2 The mass ratio of the calcium sulfate dihydrate to the sodium alginate is 0.25:1 to 0.40:

1.

6. The self-heating medical thermal blanket according to claim 1, characterized in that: The fiber transverse water-guiding layer comprises at least one of wood pulp air-laid nonwoven fabric, viscose fiber nonwoven fabric, and cellulose absorbent nonwoven fabric, wherein the areal density of the fiber transverse water-guiding layer is 40–100 g / m³. 2 .

7. The self-heating medical insulation blanket according to claim 6, characterized in that: The molecular sieve heating layer includes at least two adjacent molecular sieve accommodating areas; the fiber transverse water guiding layer includes oriented fiber bundles and / or embossed flow guiding channels extending along the plane of the blanket, and the orthogonal projection of the oriented fiber bundles and / or embossed flow guiding channels on the molecular sieve heating layer continuously spans the adjacent molecular sieve accommodating areas.

8. The self-heating medical thermal blanket according to claim 1, characterized in that: The activated 13X molecular sieve has a particle size of 0.4–1.2 mm, and its areal density in the molecular sieve heating layer is 350–700 g / m³. 2 The mass ratio of water in the water storage layer to the activated 13X molecular sieve is 0.18:1 to 0.28:

1.

9. The self-heating medical thermal blanket according to claim 1, characterized in that: The molecular sieve heating layer includes two layers of water-permeable nonwoven fabric arranged opposite each other and at least two molecular sieve containing areas located between the two layers of water-permeable nonwoven fabric. A heat-sealing dividing line, an ultrasonic welding dividing line, or a sewing dividing line is provided between adjacent molecular sieve containing areas.

10. The self-heating medical thermal blanket according to claim 2, characterized in that: The water storage layer is sheet-shaped and is disposed opposite to the molecular sieve heating layer. The planar overlap area between the water storage layer and the molecular sieve heating layer is 70% to 100% of the area of ​​the molecular sieve heating layer.

11. The self-heating medical thermal blanket according to claim 1, characterized in that: A thermal buffer layer is disposed between the molecular sieve heating layer and the patient contact layer. The thermal buffer layer includes fiber flocs and a phase change mixture disposed within the fiber flocs. The phase change mixture consists of 70%–80% n-docosahexanes by mass and 20%–30% porous silica by mass. The phase change temperature of the n-docosahexanes is 39–41°C. The areal density of the phase change mixture in the thermal buffer layer is 70 g / m³. 2 The areal density of the fiber flocculation is 30 g / m³. 2 .

12. The self-heating medical thermal blanket according to claim 1, characterized in that: The flexible encapsulation body includes a non-metallic moisture-barrier composite film disposed on the outside of the water storage layer and a skin-friendly non-woven fabric constituting the patient contact layer. The non-metallic moisture-barrier composite film is a PA / PE composite film, a PET / PE composite film, or a multilayer co-extruded polyolefin barrier film.

13. A method for preparing the self-heating medical thermal blanket according to claim 1, characterized in that, Includes the following steps: S1, sodium alginate aqueous solution is coated intermittently onto the second porous support, and after drying, sodium alginate supported support is obtained. S2, calcium sulfate dihydrate is distributed in a dry state at intervals on a first porous carrier and fixed by covering with a mesh, forming an interval calcium source region on the first porous carrier, thus obtaining a calcium sulfate dihydrate carrier. S3, the calcium sulfate dihydrate carrier and the sodium alginate carrier are aligned and stacked with the carrier edge and corresponding positioning mark as common positioning reference. The orthographic projection of the spaced calcium source area and the spaced load area in the thickness direction of the blanket coincides, and spaced point fixation is performed in the periphery and the area outside the spaced load area to obtain an independent self-gelling water control layer. S4, the activated 13X molecular sieve is laid between two layers of water-permeable nonwoven fabric, and the two layers of water-permeable nonwoven fabric are edge-sealed and area-separated to obtain the molecular sieve heating layer. S5, water is sealed in a closed water storage cavity formed by a flexible water-blocking membrane, and a fixed flow-blocking water outlet part including a water outlet hole is formed on one side of the closed water storage cavity. At least one removable isolation strip is used to cover the water outlet hole, and one end of each removable isolation strip extends to the edge of the water storage layer to form a pull-out end, thereby obtaining a water storage layer. S6, using skin-friendly non-woven fabric as the patient contact layer, and stacking it in the order of the water storage layer, the fiber transverse water guiding layer, the independent self-gelling water control layer, the molecular sieve heating layer and the patient contact layer, wherein the side of the water storage layer with the fixed flow resistance water outlet faces the fiber transverse water guiding layer, and the first porous carrier faces the fiber transverse water guiding layer. S7, cover each layer after stacking with a flexible moisture-proof encapsulation film on the side away from the patient contact layer, seal the flexible moisture-proof encapsulation film and the patient contact layer along the periphery, and make the pull-out end of the removable isolation strip extend out of the flexible encapsulation body to form a flexible encapsulation body that accommodates each layer after stacking, and encapsulate the flexible encapsulation body in a flexible moisture-proof package.

14. The preparation method according to claim 13, characterized in that, The sodium alginate aqueous solution used in S1 has a sodium alginate mass fraction of 1% to 4%, and the coating method is screen printing, stencil coating, gravure coating or dot roll coating; the second porous carrier after coating is dried at 50 to 80°C, and the moisture content after drying is not higher than 8%.

15. The preparation method according to claim 13, characterized in that, S2 sequentially includes: sieving calcium sulfate dihydrate dry powder; spreading the sieved calcium sulfate dihydrate dry powder at intervals on a first porous carrier to form the interval calcium source area; covering the interval calcium source area with a fixing mesh; connecting the fixing mesh to the first porous carrier by a point fixing method; the point fixing adopts ultrasonic point bonding, hot melt fiber point bonding or hot press point bonding, and the point fixing area is set between adjacent interval calcium source areas.

16. The preparation method according to claim 13, characterized in that, Before S4, the 13X molecular sieve is activated at 250-350°C for 2-6 hours. The activated 13X molecular sieve is cooled in a dry gas environment with a dew point not higher than -20°C and transferred between the two layers of the water-permeable nonwoven fabric. Before the periphery of the flexible encapsulation body is sealed, the dew point of the environment in which the activated 13X molecular sieve is located is kept not higher than -20°C.

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