Heat-absorbing pad

Abstract

The present application relates to a heat-absorbing pad comprising a binder resin and a heat-absorbing material, wherein the moisture content of 100 mg of the heat-absorbing pad, as measured within the temperature range of 150°C to 250°C using the Karl Fischer method, is at least 10,000 ppm. The heat-absorbing pad of the present application exhibits excellent thermal transfer delay characteristics, can exhibit excellent durability against flames, and can be effectively used to delay the transfer of heat to adjacent battery cells in the event of thermal runaway in a battery cell.

Description

Heat absorption pad

[0001] The present application relates to a heat-absorbing pad. The present application claims the benefit of priority based on Korean Patent Application No. 10-2024-0130013 filed September 25, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of the specification.

[0002] Thermal runaway in batteries occurs when the thermal stability of internal chemical substances exceeds its limits, causing the cell to rapidly release internal energy to the outside. It is defined as a drop in the cell's measured voltage, a measured temperature of dT / dt ≥ [4℃ / s], and a maximum operating temperature (approximately 120℃). Causes of thermal runaway include overcharging, collisions / drops, heat exposure, exposure to high voltage / current, and external / internal short circuits. Once thermal runaway begins, the battery's internal pressure increases, and flammable materials are ejected, leading to ignition. Subsequently, the fire heats adjacent cells and spreads rapidly. Although battery fires are classified as electrical fires and gas-based fire suppression systems are currently applied, battery modules are covered with metal protective covers, making it difficult for extinguishing agents to penetrate. Furthermore, since temperatures can rise to 1000℃ in a short period during thermal runaway, the release of extinguishing agents must occur at the very beginning of the fire. Therefore, to stop thermal runaway, sufficient cooling or complete combustion in the early stages of the fire is the ultimate means of extinguishment.

[0003] Phase Change Materials (PCMs) are materials that provide heat and cooling by releasing and absorbing energy through phase transitions. The latent heat generated by a phase transition is higher than general sensible heat, and the material converts from a solid or liquid state to another state, storing and releasing a large amount of energy at the Phase Change Temperature (PCT). Phase Change Materials are used in fields requiring energy storage and stable temperatures, such as heating pads, cooling devices, and clothing (Patent Document 1: Korean Patent Publication No. 10-2020-0107214).

[0004] The present application relates to a heat-absorbing pad. The heat-absorbing pad of the present application exhibits excellent heat transfer delay characteristics and can exhibit excellent durability against flames. The heat-absorbing pad can be usefully used to delay heat transfer to adjacent battery cells in the event of thermal runaway of a battery cell.

[0005] The present application relates to a heat-absorbing pad. The heat-absorbing pad may have the characteristic of absorbing heat generated from the surroundings. The heat-absorbing pad may include a heat-absorbing material and a binder resin. The heat-absorbing pad may include a resin composition comprising a heat-absorbing material and a binder resin in a cured state. That is, the heat-absorbing pad may include a cured product of the resin composition. The heat-absorbing pad may be the cured product of the resin composition itself. If additional layers other than the cured product of the resin composition are included, it may be referred to as a multilayer heat-absorbing pad.

[0006] Among the physical properties mentioned in this specification, those whose results are affected by the measured temperature and / or measured pressure are results measured at room temperature and / or atmospheric pressure, unless specifically stated otherwise. In this specification, the term "room temperature" refers to a natural temperature that has not been heated or cooled, and is typically a temperature within the range of about 10°C to 30°C, a temperature within the range of 20°C to 30°C, or about 23°C or about 25°C. In this specification, the unit of temperature is °C unless specifically defined otherwise. In this specification, the term "atmospheric pressure" refers to a natural pressure that has not been pressurized or depressurized, and typically means about 1 atmosphere, which is the level of atmospheric pressure. In this specification, physical properties whose results are affected by the measured humidity are, unless specifically defined otherwise, physical properties measured at natural humidity that has not been separately controlled under room temperature and atmospheric pressure conditions. The humidity may typically be 20% to 80% RH (Relative Humidity) or 40% to 80% RH (Relative Humidity).

[0007] In this specification, an endothermic material may refer to a material that absorbs or consumes heat generated from the surroundings. An endothermic material may spontaneously undergo thermal decomposition or generate new materials by utilizing the absorbed thermal energy.

[0008] The above-mentioned endothermic material may be an endothermic material that undergoes an irreversible endothermic reaction. That is, the above-mentioned endothermic material may be a material that reacts irreversibly when heated and cooled. In one example, the above-mentioned endothermic material undergoes thermal decomposition through endothermic reaction when the ambient temperature rises, and does not return to the state of the endothermic material prior to thermal decomposition even when the ambient temperature drops. This irreversibility can be advantageous for exhibiting excellent heat transition delay characteristics. On the other hand, paraffin, a representative phase change material (PCM), absorbs heat and melts into a liquid state when the ambient temperature rises, and releases heat to return to a solid state when the ambient temperature drops. The above-mentioned phase change material is a material that reacts reversibly through endothermic and exothermic reactions. The above-mentioned resin composition may not contain a phase change material that reacts reversibly as described above.

[0009] The thermal deposition temperature of the above-mentioned endothermic material may be 50°C or higher. The thermal deposition temperature of the above-mentioned endothermic material may be 300°C or lower. The above-mentioned thermal deposition temperature may also be referred to as the temperature at which the endothermic material undergoes an endothermic reaction (endothermic reaction temperature). The above-mentioned thermal decomposition may mean that when heat is applied to a substance, it chemically decomposes into a simpler substance. The above-mentioned thermal decomposition temperature may refer to the temperature at which the above-mentioned thermal decomposition occurs. The thermal decomposition temperature of the above-mentioned endothermic material may be 300°C or lower, 280°C or lower, 260°C or lower, 240°C or lower, 220°C or lower, 200°C or lower, 180°C or lower, 160°C or lower, 140°C or lower, 120°C or lower, or 100°C or lower. The thermal decomposition temperature of the above-mentioned endothermic material may specifically be 50°C or higher, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, 120°C or higher, 140°C or higher, 160°C or higher, or 180°C or higher. When the endothermic material is heated to the above-mentioned thermal decomposition temperature, it may decompose into the components constituting the endothermic material through endothermic reaction. If the thermal decomposition temperature of the endothermic material is within the above range, there is no or minimal endothermic reaction at the normal operating temperature of the battery, and if thermal runaway of the battery occurs, it may be advantageous in that it can provide a cooling effect to the ignited battery cell through the endothermic reaction (e.g., thermal decomposition) of the endothermic material and delay heat transfer to adjacent battery cells. The above-mentioned thermal decomposition temperature may be a value measured while increasing the temperature at a rate of 10°C / min using a differential scanning calorimeter (DSC Q2000, TA). A graph can be obtained from a differential scanning calorimeter with the x-axis representing temperature (°C) and the y-axis representing heat flow (W / g), and the temperature at the point where the absolute value of the heat flow (W / g) is maximum in the graph can be set as the pyrolysis temperature.

[0010] The endothermic substance may be a water-soluble substance. The water-soluble substance may refer to a substance having a solubility in water at 20°C greater than 0 g / 100 ml. In one example, the solubility of the endothermic substance in water at 20°C may be 4.5 g / 100 ml or more. Specifically, the solubility of the endothermic substance in water may be 5 g / 100 ml or more, 10 g / 100 ml or more, 15 g / 100 ml or more, 20 g / 100 ml or more, 25 g / 100 ml or more, 30 g / 100 ml or more, 35 g / 100 ml or more, or 40 g / 100 ml or more. The upper limit of the solubility of the endothermic substance in water may be, for example, 50 g / 100 ml or less. The above solubility can be determined by adding 1g of the endothermic substance to 100ml of water at a temperature of 20℃ and measuring the weight of the endothermic substance until a precipitate is formed.

[0011] The endothermic material may have thermal conductivity. In one example, the thermal conductivity (λ) of the endothermic material may be 20 W / mK or less. If the thermal conductivity of the endothermic material is within the above range, it may be advantageous for exhibiting excellent heat transfer delay characteristics. Specifically, the thermal conductivity of the endothermic material may be 15 W / mK or less, 10 W / mK or less, 5 W / mK or less, 4 W / mK or less, 3 W / mK or less, 2 W / mK or less, 1 W / mK or less, or 0.5 W / mK or less. The lower limit of the thermal conductivity of the endothermic material may be, for example, 0.001 W / mK or more. The thermal conductivity (λ) is a value defined by thermal diffusivity (α) × specific heat (Cp) × density (ρ). The thermal conductivity (λ) may be a value measured at a temperature of 25°C. The thermal conductivity of an endothermic material can be measured using known thermal conductivity measuring equipment. Alternatively, the thermal conductivity of an endothermic material is largely known, and an endothermic material satisfying the above thermal conductivity can be used.

[0012] In one example, when the endothermic material is thermally analyzed by increasing the temperature from 0°C to 350°C at a rate of 10°C / min using a differential scanning calorimeter, the endothermic peak temperature may be less than 200°C. In this specification, the endothermic peak temperature may refer to the temperature at the point where the absolute value of Heat Flow (W / g) is highest in a graph of Heat Flow (W / g) (y-axis) versus Temperature (°C) (x-axis) obtained through thermal analysis using a differential scanning calorimeter. The endothermic peak temperature may be, for example, 50°C or higher. If the endothermic peak temperature is within the above range, it may be advantageous for exhibiting excellent heat transfer characteristics. Specifically, the above endothermic peak temperature may be 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, or 100°C or lower, and may be 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, or 190°C or higher.

[0013] In one example, the endothermic material may have a single endothermic peak (one endothermic peak) at a temperature below 200°C. In another example, the endothermic material may have dispersed endothermic peaks (two or three or more endothermic peaks) at a temperature below 200°C. Having two or three or more endothermic peaks may mean having one endothermic peak with the highest absolute value of Heat Flow (W / g) and one or two or more additional endothermic peaks with the next highest absolute value of Heat Flow (W / g). Assuming the amount of heat absorbed is the same, the endothermic material having a single peak may have superior heat transfer delay characteristics. Examples of endothermic substances having a single peak include AlCl3·6H2O, MgSO4·7H2O, NiSO4·6H2O, Na4P2O7·10H2O, Sr(OH)2·8H2O, CaSO4·2H2O, etc.

[0014] In one example, the endothermic material may have an endothermic amount of 500 J / g or more. In this specification, the endothermic amount may refer to the total sum of heat (integral value on the DSC graph) from the point at which endothermic reaction begins to the point at which endothermic reaction ends. Specifically, the endothermic amount can be obtained by calculating the area of ​​the graph of the endothermic region (by integrating the graph of the endothermic region) on a graph of Heat Flow (W / g) (y-axis) against Temperature (°C) (x-axis) obtained through thermal analysis with a differential scanning calorimeter. The endothermic region may refer to the interval from the endothermic initiation temperature to the endothermic termination temperature on the graph. The area may refer to the area of ​​a closed curve formed by a straight line (A) connecting the graph point at the endothermic initiation temperature and the graph point at the endothermic termination temperature, and a continuous graph (B) of the interval from the endothermic initiation temperature to the endothermic termination temperature. If the endothermic amount at the endothermic peak is within the above range, it may be advantageous for exhibiting excellent heat transfer characteristics. Specifically, the above heat absorption amount may be 600 J / g or more, 700 J / g or more, 800 J / g or more, 900 J / g or more, 1,000 J / g or more, 1,100 J / g or more, 1,200 J / g or more, 1,300 J / g or more, 1,400 J / g or more, 1,500 J / g or more, 1,600 J / g or more, or 1,700 J / g or more, and may be 2,000 J / g or less. The above heat absorption amount may be a value measured while increasing the temperature at a rate of 10℃ / min using a differential scanning calorimeter (DSC Q2000, TA).

[0015] The endothermic material may include a water-containing material and / or a solid acid. The water-containing material may include hydrate particles and / or water microcapsules. The solid acid may include solid acid particles that exist in a solid state at room temperature, for example, about 25°C.

[0016] In one example, the endothermic substance may be hydrate particles. The hydrate particles may refer to particles containing water molecules (H2O). When hydrate particles are applied as the endothermic substance, water molecules may be dissociated from the endothermic substance through thermal decomposition. This may be advantageous for exhibiting excellent thermal transition delay characteristics. Specifically, the hydrate particles may be inorganic salts containing water molecules bonded to the crystals of a metal compound. The water contained in the hydrate particles may be referred to as crystal water. The hydrate particles are different from hydroxide particles, which may refer to a substance containing -OH (-hydroxyl group) without containing H2O.

[0017] In one example, the endothermic substance may be solid acid particles. The solid acid particles are, for example, boric acid (H3BO₃). 3) It may include particles and / or citric acid (HCl(COOH)(CH2COOH)2) particles.

[0018] In one example, the above endothermic substance is H3BO3, HOC(COOH)(CH2COOH)2(NH4)2O·5B2O3·8H2O, Mg(PO4)2·8H2O, MgCl2·6H2O, AlCl3·6H2O, Na4P2O7·10H2O, KAl(SO4)2·12H2O, NiSO4·6H2O, Mg(NO3)2·6H2O, CoSO4·7H2O, (NH4)2Fe(SO4)2·6H2O, CuSO4·5H2O, ZnSO4·7H2O, CoCl2·6H2O, CrCl3·6H2O, NiCl2·6H2O, MgSO4·7H2O, Al2(SO4)3·18H2O, Na2B4O7·10H2O, It may include one or more selected from the group consisting of Sr(OH)2·8H2O, CaC2O4·H2O, Ba(OH)2·8H2O, Ba(OH)2·H2O, Mg3(PO4)2·5H2O, Mg3(PO4)2·8H2O and FeSO4·7H2O.

[0019] In one example, the endothermic material may be a water microcapsule. The microcapsule may comprise a capsule portion and water contained within the capsule portion. The capsule portion may comprise one or more selected from the group consisting of poly(vinyl alcohol), poly(ethylene oxide), polyethylene glycol, poly(methyl methacrylate), butyl acrylate, and silicate. The size of the microcapsule may be, for example, in the range of 50 µm to 500 µm.

[0020] The content of the endothermic material may be appropriately selected within a range that does not impair the purpose of the present application. In one example, the endothermic material may be included in a range of 50 to 500 parts by weight relative to 100 parts by weight of binder resin. Specifically, the endothermic material may be included in an amount of 50 parts by weight or more, 100 parts by weight or more, 150 parts by weight or more, 200 parts by weight or more, 250 parts by weight or more, 300 parts by weight or more, 350 parts by weight or more, or 400 parts by weight or more, relative to 100 parts by weight of binder resin, and may be included in an amount of 500 parts by weight or less, 450 parts by weight or less, 400 parts by weight or less, 350 parts by weight or less, 300 parts by weight or less, 250 parts by weight or less, or 250 parts by weight or less. An endothermic pad in which the content of the endothermic particles is within the above range is suitable for production and may be advantageous for exhibiting excellent heat transfer delay characteristics.

[0021] The binder resin may include a main resin. The main resin may be a silicone resin. When a silicone resin is used as the main resin, it may be advantageous for exhibiting excellent heat transfer delay characteristics. In particular, even when an endothermic material containing water is used as the endothermic material, excellent heat transfer delay characteristics can be exhibited because no changes over time or water generation occur after mixing the main resin and the endothermic material. Meanwhile, while organic materials such as urethane resin or epoxy resin burn up in a flame, silicone resin may have better resistance to flame as the Si-O-Si siloxane chains change into SiO2 by heat.

[0022] The above silicone resin may be a polydimethylsiloxane having vinyl groups at both ends. The above silicone resin may be a compound represented by the following chemical formula 1. In the following chemical formula 1, n may be an integer greater than or equal to 1 and may be appropriately selected considering the molecular weight of the silicone resin.

[0023] [Chemical Formula 1]

[0024]

[0025] The molecular weight of the silicone resin may be selected within a range that does not impair the purpose of the present application. The molecular weight of the silicone resin refers to the molecular weight of the silicone polymer constituting the silicone resin. In one example, the molecular weight of the silicone resin may be 100,000 g / mol or less. When the molecular weight of the silicone resin is within the above range, the heat resistance performance is improved, which may be more advantageous for exhibiting excellent heat transfer delay characteristics. Specifically, the molecular weight of the silicone resin may be 90,000 g / mol or less, 80,000 g / mol or less, 70,000 g / mol or less, 60,000 g / mol or less, 50,000 g / mol or less, 40,000 g / mol or less, 30,000 g / mol or less, 25,000 g / mol or less, 20,000 g / mol or less, 15,000 g / mol or less, or 10,000 g / mol or less. The lower limit of the molecular weight of the above silicone resin may be 100 g / mol or more, 500 g / mol or more, or 1,000 g / mol from the perspective of handling the fabricated pad.

[0026] The viscosity of the silicone resin may be selected within a range that does not impair the purpose of the present application. In one example, the viscosity of the silicone resin may be 150,000 cSt or less. When the viscosity of the silicone resin is within the above range, it may be more advantageous to exhibit excellent heat transfer delay characteristics. The viscosity of the silicone resin may be 100,000 cSt or less, 50,000 cSt or less, or 10,000 cSt or less. Specifically, the viscosity of the above silicone resin may be less than 10,000 cSt, 9,000 cSt or less, 8,000 cSt or less, 7,000 cSt or less, 6,000 cSt or less, 5,000 cSt or less, 4,500 cSt or less, 4,000 cSt or less, 3,500 cSt or less, 3,000 cSt or less, 2,500 cSt or less, 2,000 cSt or less, 1,500 cSt or less, or 1,000 cSt or less. Regarding the viscosity of the silicone resin, for commercially available products, information on viscosity is provided by the seller. Therefore, a silicone resin product satisfying the above viscosity can be selected and used, and the viscosity measurement conditions can also follow those provided by the silicone resin seller. In one example, viscosity in cSt units can be measured using a Canon-Fenske Viscomete. The method for measuring viscosity using a Canon-Fenske viscometer is known. For example, cSt viscosity can be calculated from Efflux time x Viscometer Factor. Efflux time refers to the time it takes for a sample (relative to the top surface of the fluid) to descend from a specific upper mark to a specific lower mark due to gravity after filling the viscometer with the sample. At this time, the viscometer filled with the sample can be placed in a constant temperature water bath to allow the sample to reach the temperature to be measured, and then the time can be measured.The above temperature may be, for example, a temperature within the range of about 10°C to 30°C, about 20°C, or about 25°C. The Viscometer Factor is a coefficient unique to the viscometer at the temperature at which viscosity is to be measured, provided by the manufacturer of the viscometer. If the coefficient is not provided by the manufacturer, the coefficient may be corrected directly using water or other standard liquids.

[0027] The binder resin may further include a curing agent. The curing agent may be suitable for curing the main resin. In one example, when the main resin is a silicone resin, a silane compound may be used as the curing agent. The silane compound may refer to a compound having -SiH (silicon-hydride). The -SiH may react with the vinyl groups of the silicone resin. The silane compound may have at least one -CH3 group at the terminal and / or side chain It may be a polydimethylsiloxane substituted with H. In one example, the curing agent may be a pendent type curing agent. The pendent type curing agent may be a polydimethylsiloxane in which at least one -CH3 group of the pendent chain is substituted with -H and both ends are -CH3. In another example, the curing agent may be a hybrid type curing agent. The hybrid type curing agent may be a polydimethylsiloxane in which -CH3 groups at both ends are substituted with -H and at least one -CH3 group of the pendent chain is also substituted with -H.

[0028] In one example, a curing agent may be included in the resin composition such that the H / V ratio is within the range of 1 to 20. H is a value defined as H mmol / g × H wt%, and V is a value defined as V mmol / g × V wt%. In the above, H mmol / g refers to the mmol of Si-H (silicon-hydrogen) per gram of curing agent included in the resin composition, and V mmol / g refers to the mmol of Si-Vi (silicon-vinyl) per gram of silicone resin included in the resin composition. In the above, H wt% refers to the weight fraction of the curing agent relative to the weight of the total resin composition, and V wt% refers to the weight fraction of the silicone resin relative to the weight of the total resin composition. In the above, the weight fraction of the total resin composition is 100 wt%.

[0029] In one example, the resin composition and / or heat-absorbing pad may not include an amine compound and / or isocyanate compound. The amine compound and / or isocyanate compound may not be suitable for formulation with the heat-absorbing material. The amine compound may be a curing agent when an epoxy resin is used as the main resin, and the isocyanate compound may be a curing agent when a polyol resin or urethane resin is used as the main resin. According to the present application, the epoxy resin, polyol resin and / or urethane resin may not be included as the main resin.

[0030] The resin composition and / or heat-absorbing pad may further include a catalyst. The catalyst may promote the reaction between the main resin and the curing agent. In one example, the catalyst may promote a hydrosilylated addition reaction between a carbon-carbon double bond in the silicone resin and a SiH group in the curing agent. In one example, the catalyst may be a platinum group catalyst. The platinum group catalyst may include a platinum-based metal catalyst, a palladium-based metal catalyst, a rhodium-based metal catalyst, or a mixture thereof. In another example, the catalyst may be a metal salt catalyst. The metal salt catalyst may include a tin-based metal salt such as bis(2-ethylhexanoate)tin or dibutyldilauryltin, a zinc-based metal salt such as zinc octoate, an iron-based metal salt such as iron octoate, or a mixture thereof. The above catalyst may be included in a range of 0.01 to 10 parts by weight, 0.01 to 5 parts by weight, 0.01 to 3 parts by weight, 0.01 to 1 part by weight, or 0.01 to 0.5 parts by weight per 100 parts by weight of binder resin.

[0031] The resin composition and / or heat-absorbing pad may further include additives in addition to the main resin, curing agent, and catalyst. In one example, the resin composition may further include a dispersant. For example, an amino-silicone dispersant may be used as the dispersant. The dispersant may be included in a range of 0.1 to 10 parts by weight, 0.1 to 5 parts by weight, or 0.5 to 5 parts by weight per 100 parts by weight of the binder resin.

[0032] In one example, the resin composition and / or heat-absorbing pad may further comprise a chain extender. As the chain extender, for example, a compound having -SiH (silicon-hydride) at both ends may be used. The -SiH may react with the vinyl groups of the silicone resin. In one example, the chain extender may be a polydimethylsiloxane in which -CH3 at both ends are substituted with -H and the side chain is -CH3. When the resin composition comprises both a curing agent and a chain extender, the curing agent and the chain extender may be included in the resin composition such that the H / V ratio is within the range of 1 to 20. H is a value defined as (H1 mmol / g ≠ H1 wt% + H2 mmol / g ≠ H2 wt%), and V is a value defined as V mmol / g ≠ V wt%. In the above, H1 mmol / g refers to the mmol of Si-H (silicon-resin) per gram of the curing agent included in the resin composition, H2 mmol / g refers to the mmol of Si-H (silicon-resin) per gram of the chain extender included in the resin composition, and V mmol / g refers to the mmol of Si-Vi (silicon-vinyl) per gram of the silicone resin included in the resin composition. In the above, H1 wt% refers to the weight fraction of the curing agent relative to the weight of the total resin composition, H2 wt% refers to the weight fraction of the chain extender relative to the weight of the total resin composition, and V wt% refers to the weight fraction of the silicone resin relative to the weight of the total resin composition. In the above, the weight fraction of the total resin composition is 100 wt%.

[0033] In one example, the resin composition and / or heat-absorbing pad may further comprise a curing retardant. The curing retardant may be, for example, a compound having a carbon-carbon double bond or a carbon-carbon triple bond. The above-mentioned curing retardant is 1-ethynyl-1-cyclohexanol, 3-methyl-1-pentene-3-ol, 2-methyl-3-butyn-2-ol, 3-phenyl-3-butyn-2-ol, 2-phenyl-3-butyn-2-ol, 3,5-dimethyl-1-hexine-3-ol, 1,5-hexadiine, 1,6-heptadiine, 3,5-dimethyl-1-hexine, 2-ethyl-3-butine, 2-phenyl-3-butine, 1,3-divinyltetramethyldisiloxane, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane, 1,3-divinyl-1,3-diphenyldimethyldisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane and It may be one or more selected from the group consisting of divinyl-1,1,3,3-detramethyldisilazane, but is not limited thereto. The curing retardant may be included in the range of 0.1 to 10 parts by weight, 0.1 to 5 parts by weight, or 0.5 to 5 parts by weight per 100 parts by weight of binder resin.

[0034] In one example, the resin composition and / or heat-absorbing pad may further include a flame retardant. The flame retardant may be a solid flame retardant in the form of a filler or a liquid flame retardant. Liquid flame retardants may be suitably used when the amount of filler filled in the resin composition and / or heat-absorbing pad is large; for example, TEP, TCPP, etc. described below are representative liquid flame retardants. The flame retardant may include organic flame retardants, inorganic flame retardants, and / or organic-inorganic composite flame retardants. Organic flame retardants may include phosphorus-based flame retardants and / or melamine-based flame retardants. Inorganic flame retardants may include metal hydroxide-based flame retardants. Organic-inorganic composite flame retardants may include phosphorus-metal-based flame retardants.

[0035] In one example, the flame retardant may include one or more selected from the group consisting of: phosphorus-based flame retardants including ammonium polyphosphate (APP), red phosphorus, tris(2-chloroethyl) phosphate (TCEP), isopropylphenyl diphenyl phosphate (IPDP), tris(1-chloro-2-propyl) phosphate (TCPP), triphenyl phosphate (TPP), and triethyl phosphate (TEP); melamine-based flame retardants including melamine cyanurate; metal hydroxide-based flame retardants including aluminum hydroxide and magnesium hydroxide; and organic-inorganic composite flame retardants including aluminum diethyl phosphinate. According to one embodiment of the present application, the flame retardant may include a phosphorus-based flame retardant and a metal hydroxide flame retardant.

[0036] In one example, a coating layer may be present on the surface of the flame retardant. The coating layer may be appropriately selected considering the function to be added to the flame retardant. The coating layer may include, for example, one or more selected from the group consisting of a silicone-based coating layer, an epoxy-based coating layer, and a melamine-based coating layer. As a specific example, if the APP flame retardant has the coating layer, it may exhibit superior water resistance.

[0037] In one example, the flame retardant may be included in a range of 10 to 300 parts by weight, 10 to 200 parts by weight, or 30 to 150 parts by weight per 100 parts by weight of binder resin.

[0038] In one example, the resin composition and / or heat-absorbing pad may further include a flame retardant adjuvant. The flame retardant adjuvant is an additive that can be added to the resin composition along with the flame retardant to further improve the flame retardancy of the resin composition and / or heat-absorbing pad, and may include, for example, PTFE (Polytetrafluoroethylene). If the resin composition and / or heat-absorbing pad further include a flame retardant, it may be advantageous in terms of improving the heat transfer delay time, suppressing crack formation due to flame, and reducing the final insulation temperature.

[0039] In one example, the viscosity of the resin composition may be 500,000 cps or less. When the viscosity of the resin composition is within the above range, it may be advantageous to manufacture an endothermic pad through curing, and the endothermic pad manufactured therefrom may exhibit excellent heat transfer delay characteristics. Specifically, the viscosity of the resin composition may be 450,000 cps or less, 400,000 cps or less, 350,000 cps or less, 300,000 cps or less, 250,000 cps or less, 200,000 cps or less, 150,000 cps or less, or 100,000 cps or less. From the perspective of the pad manufacturing process, the lower limit of the viscosity of the resin composition may be 1,000 cps or more, 5,000 cps or more, 10,000 cps or more, 30,000 cps or more, or 50,000 cps or more. The above viscosity was determined using a Brookfield DV2T HB viscometer at a temperature of 25℃, a rotation speed of 1.2 rpm, and a shear rate (sec -1 ) 2.4, it may be a value measured under the condition of spindle CPA 52Z.

[0040] In one example, the resin composition may be a room-temperature curable resin composition. Accordingly, the resin composition can be cured by maintaining it at room temperature (e.g., about 20°C to 30°C), and separate processes for curing, such as the application of moisture, the application of heat, or irradiation with active energy rays (e.g., ultraviolet rays), may not be required. Furthermore, considering that the resin composition may be used as a heat-absorbing pad containing an endothermic material, it may be more advantageous to be a room-temperature curable type because it may be sensitive to heat that may entail a phase change of the endothermic material. Additionally, the room-temperature curable resin composition may be advantageous when curing must be performed inside a battery. This is because applying heat to the battery for curing inside the battery can be dangerous. Moreover, the room-temperature curable resin composition may be advantageous in that the curing speed can be easily controlled, as it can be cured by applying heat if necessary. In other words, in this specification, a room-temperature curable resin composition means that it can be cured by maintaining it at room temperature, and is not limited to a resin composition that is cured only by maintaining it at room temperature.

[0041] In one example, the moisture content measured by the Karl Fisher method for 100 mg of the heat-absorbing pad within a temperature range of 150°C to 250°C may be 10,000 ppm or more. A heat-absorbing pad containing moisture in this way may exhibit excellent heat transfer delay characteristics and excellent resistance to flame. The Karl Fisher method is a method known for measuring the moisture content of a sample. Specifically, the moisture content of the heat-absorbing pad may be measured by Karl-Fisher Oven Titration. Karl-Fisher Oven Titration is a method in which moisture is evaporated from a sample using an oven and then measured using the Karl Fisher titration method. The upper limit of the moisture content measured by the Karl Fisher method for 100 mg of the heat-absorbing pad within a temperature range of 150°C to 250°C may be 300,000 ppm or less.

[0042] In one example, for 100 mg of the heat-absorbing pad, at least one moisture content measured by the Karl Fisher method at temperatures of 150°C, 200°C, and 250°C, respectively, may be 10,000 ppm or more. In another example, for 100 mg of the heat-absorbing pad, the moisture content measured by the Karl Fisher method at temperatures of 150°C, 200°C, and 250°C, respectively, may all be 10,000 ppm or more.

[0043] As a specific example, for 100 mg of heat-absorbing pad, the moisture content measured at 150°C by the Karl Fisher method may be 10,000 ppm or more, 30,000 ppm or more, 50,000 ppm or more, 100,000 ppm or more, or 130,000 ppm or more, and the upper limit of the moisture content may be 300,000 ppm or less, 250,000 ppm or less, 200,000 ppm or less, 150,000 ppm or less, 100,000 ppm or less, or 50,000 ppm or less.

[0044] As a specific example, for 100 mg of heat-absorbing pad, the moisture content measured at 200°C by the Karl Fisher method may be 10,000 ppm or more, 30,000 ppm or more, 50,000 ppm or more, 100,000 ppm or more, 130,000 ppm or more, or 150,000 ppm or more, and the upper limit of the moisture content may be 300,000 ppm or less, 250,000 ppm or less, 200,000 ppm or less, 150,000 ppm or less, or 100,000 ppm or less.

[0045] As a specific example, for 100 mg of heat-absorbing pad, the moisture content measured at 250°C by the Karl Fisher method may be 10,000 ppm or more, 50,000 ppm or more, 100,000 ppm or more, or 150,000 ppm or more, and the upper limit of the moisture content may be 300,000 ppm or less, 250,000 ppm or less, 200,000 ppm or less, or 150,000 ppm or less.

[0046] In one example, the heat-absorbing pad may have a porous structure. A heat-absorbing pad having a porous structure may be referred to as a heat-absorbing foam pad. In one example, the density of the heat-absorbing foam pad is 1 g / cm³. 3 It may be less than or equal to. The density of the heat-absorbing foam pad is, for example, 0.9 g / cm³3 Below, 0.8 g / cm³ 3 Less than or equal to 0.7 g / cm³ 3 It may be less than or equal to. The lower limit of the density of the heat-absorbing foam pad is, for example, 0.1 g / cm³. 3 Above or 0.2 g / cm³ 3 It could be more than that.

[0047] In one example, an endothermic foam pad can be obtained by including a solvent in a resin composition for manufacturing the endothermic pad and evaporating the solvent to form a porous structure. In another example, an endothermic foam pad can be obtained by including foam particles in a resin composition for manufacturing the endothermic pad to form a porous structure.

[0048] In a method for forming a porous structure by evaporating the above solvent, the solvent may be an organic solvent. The conditions for evaporating the solvent may be performed within a range suitable for curing while forming a porous structure on the heat-absorbing pad. The temperature for evaporating the solvent may be higher than the boiling point of the solvent used. In one example, the organic solvent component may have a boiling point of 65°C or higher. The boiling point of the organic solvent component may be, for example, within the range of 65°C to 150°C. The above boiling point may be 65°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, 85°C or higher, 90°C or higher, 95°C or higher, 100°C or higher, or 105°C or higher, and may be 145°C or lower, 140°C or lower, 135°C or lower, 130°C or lower, 125°C or lower, 120°C or lower, 115°C or lower, 110°C or lower, 105°C or lower, 100°C or lower, 95°C or lower, 90°C or lower, 85°C or lower, or 80°C or lower.

[0049] In another example, the heat-absorbing pad may not have a porous structure. To distinguish a heat-absorbing pad that does not have a porous structure from a heat-absorbing foam pad, it may be referred to as a heat-absorbing sheet. In this specification, the statement that the heat-absorbing pad does not have a porous structure may mean a heat-absorbing pad for which no intentional process is performed to form a porous structure. Accordingly, the heat-absorbing sheet may not contain foaming particles (foaming agents) for foaming and / or a solvent for evaporation. The density of the heat-absorbing sheet is 1 g / cm³. 3 It may exceed. The upper limit of the density of the above-mentioned heat-absorbing hard pad is, for example, 5 g / cm³. 3 Below, 3 g / cm³ 3 Less than or equal to 1.5 g / cm³ 3 It may be less than.

[0050] The heat-absorbing pad described above may have a heat transfer delay effect. In this specification, the heat transfer delay effect may mean that when a flame is radiated onto a single heat-absorbing pad (in a state where no other layer affecting the thermal properties of the heat-absorbing pad is laminated), the heat-absorbing pad absorbs heat and maintains the temperature of the heat-absorbing pad for a certain period without rising. When a heat-absorbing pad having a heat transfer delay effect is applied to a battery cell, the transfer of heat to adjacent battery cells can be effectively delayed even if the battery cell to which the heat-absorbing pad is applied ignites. In this specification, when describing the characteristics of the heat-absorbing pad regarding a flame, the flame may refer to a flame resulting from the combustion of LPG (Liquid Petroleum Gas) or butane gas. The temperature of the flame may be, for example, about 1000°C or higher. The upper limit of the flame temperature may be, for example, 2000°C or lower or 1500°C or lower.

[0051] The fact that the heat-absorbing pad has a heat transfer delay effect may mean that the heat-absorbing pad has a heat transfer delay section. The heat transfer delay section can be defined as a continuous section in which the temperature change is less than 10°C or 5°C or less in a graph of temperature (°C) versus time (seconds) measured while applying a flame to the heat-absorbing pad. The temperature change being less than 10°C or 5°C or less means that the temperature rise per second is less than 10°C or 5°C or less. The heat transfer delay section may be due to the endothermic reaction of the heat-absorbing material. In one example, in a graph of temperature (°C) versus time (seconds) measured while applying a flame to the heat-absorbing pad, a heat transfer delay section may appear after a temperature rise section. In the temperature rise section, the starting temperature (temperature at 0 seconds) is approximately 25°C, and the temperature may increase almost linearly until the start time of the heat transfer delay section. Subsequently, the temperature may remain almost constant in the heat transfer delay section. After the above-mentioned heat transfer delay section, a temperature rise section may appear again. If distinction is necessary, the temperature rise section before the heat transfer delay section may be referred to as the first temperature rise section, and the temperature rise section after the heat transfer delay section may be referred to as the second temperature rise section. After the second temperature rise section, the temperature may converge to a constant temperature again, and this temperature may be referred to as the final adiabatic temperature. The above-mentioned final adiabatic temperature may appear, for example, after about 3 minutes, about 5 minutes, or about 10 minutes have passed since the flame was radiated onto the heat absorption pad.

[0052] In one example, the heat transfer delay temperature of the heat-absorbing pad may be 50°C or higher. The heat transfer delay temperature may be, for example, 60°C or higher, 70°C or higher, 80°C or higher, 90°C or higher, 100°C or higher, 110°C or higher, 120°C or higher, 130°C or higher, 140°C or higher, 150°C or higher, 160°C or higher, 170°C or higher, 180°C or higher, or 190°C or higher. The above heat transfer delay temperature may be, for example, 300°C or lower, 290°C or lower, 280°C or lower, 270°C or lower, 260°C or lower, 250°C or lower, 240°C or lower, 230°C or lower, 220°C or lower, 210°C or lower, 200°C or lower, 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, or 100°C or lower. The above heat transfer delay temperature may refer to the temperature of a part of the heat transfer delay interval (for example, the start time and / or end time of the heat transfer delay interval) or may refer to the temperature over the entire time of the heat transfer delay interval. If the heat transfer delay temperature is within the above range, it may be suitable for delaying rapid ignition caused by flames in the early stages by absorbing the initial heat generated when the battery cell explodes.

[0053] In one example, the heat transfer delay time of the heat-absorbing pad may be, for example, 5 seconds or more. The heat transfer delay time may be 10 seconds or more, 20 seconds or more, 30 seconds or more, 40 seconds or more, 60 seconds or more, 80 seconds or more, 100 seconds or more, 120 seconds or more, 140 seconds or more, 160 seconds or more, 180 seconds or more, or 200 seconds or more. The longer the heat transfer delay time, the more advantageous it is, and although there is no specific upper limit, it may be, for example, 60 minutes or less.

[0054] The heat-absorbing pad may have irreversibility, meaning its shape does not return to its original state after heating and cooling. In one example, the X-ray diffraction (XRD) pattern of the heat-absorbing pad measured after heating it to 200°C and cooling it to room temperature may differ from the X-ray diffraction (XRD) pattern of the heat-absorbing pad before heating. Heating the heat-absorbing pad to 200°C may be maintained for about 60 minutes. The heat-absorbing pad before heating refers to the heat-absorbing pad at room temperature without heating. The room temperature may be, for example, in the range of 20°C to 30°C or about 25°C. If the heat-absorbing pad does not have the irreversibility, the XRD patterns before and after heating may be identical. Specifically, when XRD analysis is performed on an endothermic pad, a graph can be obtained where the x-axis is 2θ (2Theta) and the y-axis is intensity (au) (θ is the angle of incidence of the diffracted X-ray, and intensity is the intensity of the diffracted X-ray). Multiple diffraction peaks appear on the graph, and a pattern can be obtained from them. Different XRD patterns may mean that at least one of the multiple diffraction peaks does not appear. Identical XRD patterns may mean that the multiple diffraction peaks appear identically.

[0055] In one example, the heat-absorbing pad may have a first temperature delay section and a second temperature delay section after the first temperature delay section. The first temperature delay section may be due to the heat absorption of the heat-absorbing pad, and the second temperature delay section may be due to the thermal insulation of the heat-absorbing pad. The definitions of the first and second temperature delay sections may each be the definitions of the heat transfer delay sections. That is, the first temperature delay section may be the first heat transfer delay section, and the second temperature delay section may be the second heat transfer delay section. Specifically, the first and second temperature delay sections may each refer to a continuous section (a section maintained for at least 5 seconds) in which the temperature change is less than 10°C or 5°C or less in a graph of temperature (°C) versus time (seconds) measured while applying a flame from the combustion of butane gas to the heat-absorbing pad. FIG. 1 is a diagram for explaining the first and second temperature delay sections. Figure 1 is intended to aid in understanding the first and second temperature delay periods, and the actual time and temperature values ​​of the temperature delay period of the heat absorption pad are not limited by Figure 1.

[0056] As shown in FIG. 1, the temperature before applying a flame to the heat-absorbing pad (0 sec) may be approximately 25°C. When a flame is continuously applied to the heat-absorbing pad, a first rising section (A) in which the temperature rises over time may be indicated. Subsequently, a first temperature delay section (B) in which the temperature is maintained over time may be indicated. Subsequently, a second rising section (C) in which the temperature rises over time may be indicated. Subsequently, a second temperature delay section (D) in which the temperature is maintained over time may be indicated. Subsequently, a third rising section (E) in which the temperature rises over time may be indicated.

[0057] In one example, the temperature (T1) of the first temperature delay section and the temperature (T2) of the second temperature delay section of the heat-absorbing pad may satisfy the following equations 1 and 2. That is, the temperature of the first temperature delay section may be equal to or greater than the thermal decomposition temperature of the heat-absorbing material. Additionally, the temperature of the second temperature delay section may be higher than the temperature of the first temperature delay section.

[0058] [Equation 1]

[0059] A ≤ T1

[0060] [Equation 2]

[0061] T1 < T2

[0062] In Equation 1, A is the thermal decomposition temperature (°C) of the endothermic substance, T1 is the temperature (°C) of the first temperature lag period, and T2 is the temperature (°C) of the second temperature lag period.

[0063] In one example, the temperature of the first temperature delay section of the heat absorption pad may be in the range of 50°C to 200°C. The temperature of the first temperature delay section may refer to the temperature throughout the entire first temperature delay section, or it may refer to the temperature at the point where the first temperature delay section begins or the temperature at the point where the second temperature delay section ends. If the temperature of the first temperature delay section is within the above range, it may be suitable for effectively delaying thermal runaway of the battery cell. Specifically, the temperature may be 80°C or higher, 100°C or higher, 120°C or higher, or 140°C or higher, and may be 200°C or lower, 180°C or lower, 160°C or lower, 140°C or lower, or 120°C or lower.

[0064] The temperature of the second temperature delay section of the heat absorption pad may be greater than 200°C and less than 400°C. The temperature of the second temperature delay section may refer to the temperature throughout the entire second temperature delay section, or it may refer to the temperature at the point where the second temperature delay section begins or the temperature at the point where the second temperature delay section ends. If the temperature of the second temperature delay section is within the above range, it may be suitable for effectively delaying thermal runaway of the battery cell. Specifically, the temperature may be 210°C or higher, 220°C or higher, 230°C or higher, 240°C or higher, or 250°C or higher, and may be less than 400°C, 390°C or lower, 380°C or lower, 370°C or lower, 360°C or lower, or 350°C or lower.

[0065] In one example, the difference (T2-T1) between the temperature (T2) at which the second temperature delay period is maintained and the temperature (T1) at which the first temperature delay period is maintained may be 100°C or more. The above T2-T1 may be, for example, 150°C or more, 200°C or more, and 350°C or less.

[0066] In one example, the time (S2) during which the second temperature delay period is maintained may be longer than the time (S1) during which the first temperature delay period is maintained (i.e., S2-S1>0). The time (S1) during which the first temperature delay period is maintained may be, for example, 30 seconds or more. The time (S1) during which the first temperature delay period is maintained may be, for example, less than 60 seconds or 50 seconds or less. The time (S2) during which the second temperature delay period is maintained may be, for example, 60 seconds or more. The longer the time during which the second temperature delay period is maintained, the more advantageous it is, and while there is no specific upper limit, it may be, for example, 60 minutes or less.

[0067] In one example, the thickness of the heat-absorbing pad may be, for example, 0.5 mm or more. Specifically, the thickness of the heat-absorbing pad may be 1 mm or more, 1.5 mm or more, 2 mm or more, 2.5 mm or more, or 3 mm or more. When the thickness of the heat-absorbing pad is within the above range, it may be advantageous to improve heat absorption performance and exhibit excellent heat transfer delay characteristics. The upper limit of the thickness of the heat-absorbing pad may be appropriately adjusted considering the battery module to which the pad is to be applied, for example, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, or 3 mm or less. In another example, the thickness of the pad may be less than 4 mm, 3.5 mm or less, 3.0 mm or less, 2.5 mm or less, or 2.0 mm or less. When the thickness of the pad is within the above range, it may be more advantageous in that it can exhibit a secondary temperature delay section.

[0068] The present application relates to the use of the resin composition and / or the heat-absorbing pad. In one example, the present application relates to a battery module comprising the resin composition and / or the heat-absorbing pad. Additionally, the present application relates to a battery pack cover comprising the resin composition and / or the heat-absorbing pad. The battery module or battery pack cover may comprise the resin composition in a cured state (i.e., a cured product of the resin composition).

[0069] The battery module described above may include a module case and battery cells. The battery cells may be housed within the module case. One or more battery cells may exist within the module case, and multiple battery cells may be housed within the module case. The number of battery cells housed within the module case is not specifically limited and is adjusted according to the intended use, etc. The battery cells housed within the module case may be electrically connected to one another. The type of battery cell housed within the module case is also not specifically limited, and various known battery cells may all be applied. In one example, the battery cell may be of the pouch type. A pouch-type battery cell may typically include an electrode assembly, an electrolyte, and a pouch outer casing.

[0070] A module case may include at least a side wall and a bottom plate forming an internal space in which a battery cell can be housed. Additionally, the module case may further include a top plate that seals the internal space. The side wall, bottom plate, and top plate may be formed integrally with each other, or the module case may be formed by assembling separate side walls, bottom plates, and / or top plates. The shape and size of such a module case are not particularly limited and may be appropriately selected depending on the application or the shape and number of battery cells housed in the internal space. In the above, the terms "top plate" and "bottom plate" are relative terms used to distinguish between the plates constituting the module case, as there are at least two plates. That is, it does not mean that in actual use, the top plate must necessarily be located at the top and the bottom plate must necessarily be located at the bottom.

[0071] The resin composition and / or heat-absorbing pad may be present on one side of a battery cell. If the battery module comprises a plurality of battery cells, the resin composition and / or heat-absorbing pad may be disposed between the battery cells. The resin composition and / or heat-absorbing pad maintain their original form without a change of state at the operating temperature of the battery, but when thermal runaway occurs, they can provide a cooling effect to the ignited cell through a change of state and delay the transfer of heat to adjacent cells.

[0072] The present application relates to a heat-absorbing pad. The heat-absorbing pad of the present application exhibits excellent heat transfer delay characteristics and can exhibit excellent durability against flames. The heat-absorbing pad can be usefully used to delay heat transfer to adjacent battery cells in the event of thermal runaway of a battery cell.

[0073] Figure 1 is a diagram illustrating the first and second temperature delay intervals.

[0074] The present application will be described in detail below through embodiments according to the present application, but the scope of the present application is not limited by the embodiments presented below.

[0075] Measurement Example 1. Measurement of Endothermic Peak Temperature and Endothermic Amount

[0076] The amount of endothermic heat was measured using a differential scanning calorimeter (DSC Q2000, TA). Specifically, 3 mg to 5 mg of the sample was placed in a pan and covered with a lid. The pan and lid were of the T-zero Hermetic type. A hole was drilled in the lid due to the pressure caused by the gas generated during heating. Subsequently, the sample was stabilized in an isothermal state at 0°C for 3 minutes, and then thermal analysis was performed while increasing the temperature to 350°C at a rate of 10°C / min. Through thermal analysis, a graph was obtained with the x-axis representing temperature (°C) and the y-axis representing heat flow (W / g), and the endothermic peak temperature and the amount of endothermic heat were derived from the graph.

[0077] Measurement Example 2. Density Measurement

[0078] The measurement target (heat absorption pad) was cut into a sample measuring 3cm x 3cm, and its thickness (cm) and weight (g) were measured. Density (g / cm²) 3 ) was calculated from weight (g) / width (cm) × length (cm) × thickness (cm).

[0079] Example 1

[0080] In the container of a paste mixer (Daehwa Tech, PDM-1K equipment), 88.5 parts by weight of silicone resin (VP10000, Dami Polychem) with a viscosity of 1000 cSt and 11.5 parts by weight of a random pendant type silicon-hydride curing agent (Andisil XL12, AB Specialty Silicones) were added, and the mixture was made to 100 parts by weight of binder resin. With respect to 100 parts by weight of binder resin, 120 parts by weight of Mg3(PO4)2·8H2O particles (Taepyeong Chemical) and 3 parts by weight of a dispersant (LP X 21879, BYK) were added, and the mixture was stirred for 2 minutes at 600 rpm rotation and 500 rpm rotation. After confirming that a uniform mixture had been achieved, the particles were degassed once and mixed for 2 minutes at 600 rpm rotation and 200 rpm rotation. Subsequently, 0.3 parts by weight of a platinum-based catalyst (SRX-212, Dow Chemical) were added, and secondary degassing was performed. The mixture was blended for 2 minutes at 600 rpm and 200 rpm to prepare a resin composition. The endothermic peak temperature of the Mg3(PO4)2·8H2O particles was approximately 179°C, and the endothermic amount was approximately 1016 J / g.

[0081] A frame-shaped silicone dam was prepared on a fluorine release liner (the overall size of the dam is width × height = 12 cm × 12 cm, the internal size is width × height = 10 cm × 10 cm, and the height of the dam is 2 mm). The resin composition was applied inside the silicone dam and then covered with a fluorine release liner. After pressing the fluorine release liner with a glass plate, the liner was left to cure at room temperature (25°C) for 24 hours to produce a heat-absorbing pad with a uniform thickness (2 mm). The density of the heat-absorbing pad is approximately 1.37 g / cm³. 3 The heat absorption peak temperature of the above heat absorption pad was approximately 228°C, and the amount of heat absorbed was approximately 503 J / g.

[0082] Example 2

[0083] 68 parts by weight of silicone resin (VP10000, Dami Polychem Co.) with a viscosity of 1000 cSt and 32 parts by weight of curing agent (Andisil XL12, AB Specialty Silicones Co.) were added to the container of a paste mixer (Daehwa Tech Co., PDM-1K equipment) and 100 parts by weight of binder resin were added. A mixture was prepared by adding 125 parts by weight of boric acid (H3BO3) particles (Daejeong Hwakum Co.), 40 parts by weight of APP (Ammonium Phosphate) (FR-624E, Chempia Co.) as flame retardant particles, 20 parts by weight of aluminum hydroxide particles (HWF-20, Chalco Co.), 0.9 parts by weight of dispersant (LP X 21879, BYK Co.), 0.8 parts by weight of curing retardant (VMC, HRS Co.), 26 parts by weight of hexane solvent (Daejeong Hwakum Co.), and 0.4 parts by weight of catalyst (SRX-212, Dow Co.) to 100 parts by weight of binder resin, and then mixing for 1 minute at 600 rpm and 500 rpm.

[0084] After placing a fluorine release film on an automatic coating device and adjusting the coating gap, the above-mentioned mixture was poured onto the fluorine release film and coated. Subsequently, an endothermic pad was manufactured by drying in a Matisse oven at 130°C for 10 minutes. The thickness of the manufactured endothermic pad was approximately 2.0 mm. The endothermic peak temperature of the H3BO3 particles was approximately 133°C, and the endothermic amount was approximately 1169 J / g. The density of the endothermic pad was approximately 0.5-0.7 g / cm³. 3 The heat absorption peak temperature of the above heat absorption pad was approximately 164°C, and the amount of heat absorbed was approximately 639 J / g.

[0085] Comparative Example 1

[0086] A polyurethane foam pad (LGC) with a thickness of about 2 mm that does not contain endothermic particles was prepared as Comparative Example 1.

[0087] Comparative Example 2

[0088] A silicone foam pad (L2Y) containing Al(OH)3 particles and having a thickness of about 2 mm was prepared as Comparative Example 2. The endothermic peak temperature of the foam pad was about 301°C and the amount of endothermic heat was about 284 J / g.

[0089] Comparative Example 3

[0090] A heat-dissipating adhesive (TRU7, LGC) containing alumina and having a thickness of about 2 mm was prepared as Comparative Example 3.

[0091] Comparative Example 4

[0092] An aerogel (LGC) with a thickness of about 2 mm was prepared as Comparative Example 4.

[0093] Comparative Example 5

[0094] A ceramic paper with a thickness of about 2 mm (Hi-Tems Co.) was prepared as Comparative Example 5.

[0095] Evaluation Example 1. Evaluation of thermal transition delay characteristics

[0096] The heat transfer delay characteristics were evaluated for the pads prepared in Examples 1 and 2, the pads prepared in Comparative Examples 1 to 5, the adhesive, the aerogel, and the ceramic paper (hereinafter referred to as samples). Specifically, the samples were prepared by cutting them into width × length = 6 cm × 6 cm. SUS frames were attached to the front and back sides of the samples. The SUS frames serve to prevent the samples from bending due to flames. The samples with the attached SUS frames were fixed vertically to a jig using clamps (the main surface of the sample is perpendicular to the ground, and the thickness direction of the sample is parallel to the ground). A butane gas torch (butane gas: Sun Lighter Gas 295ML, Taeyang Industrial Co., Ltd., gas torch: 500JET, Honest Co., Ltd.) was placed on the first main surface side of the sample, and a thermal imaging camera (A655SC, FLIR Co., Ltd.) was placed on the second surface side of the sample, opposite to the first main surface. The pixel resolution of the above thermal imaging camera is 640×480, and the upper limit of the measurement temperature is 660℃. The gas torch was positioned so that the flame-emitting part of the gas torch was centered on the first main surface of the sample, and the lens of the thermal imaging camera was positioned so that it was centered on the second main surface of the sample. In addition, the distance between the first main surface of the sample and the flame-emitting part of the gas torch was approximately 3 cm, and the distance between the second main surface of the sample and the lens of the thermal imaging camera was approximately 40 cm. The ambient temperature before the flame was emitted from the gas torch was approximately 25℃. While heating the sample by emitting a flame from the torch, the temperature of the second main surface of the sample over time was measured using the thermal imaging camera. The thermal imaging camera measures the infrared radiation emitted by the sample and calculates the temperature based on the measured infrared radiation values. The duration of flame emission by the gas torch was set to 3 minutes. The temperature measured by the thermal imaging camera is the temperature of the highest temperature point in the heated part of the sample.

[0097] As described above, when a flame is applied to a sample, if the sample absorbs heat and maintains its temperature for a certain period without rising, it can be considered to have a heat transfer delay effect. Specifically, when a flame is applied to a sample, the continuous section (heat transfer delay section) in which the temperature change is 5°C or less in the graph of the sample's temperature (°C) against the measured time (seconds) is 5 seconds or longer is evaluated as having a heat transfer delay effect, and the temperature at the end point of the heat transfer delay section is set as the heat transfer delay temperature and is listed in Table 1 below.

[0098] Evaluation Example 2. Evaluation of durability against flame

[0099] The durability against flame was evaluated for the pads prepared in Examples 1 and 2, the pads prepared in Comparative Examples 1 to 5, the adhesive, the aerogel, and the ceramic paper (hereinafter referred to as samples). Specifically, after setting up as in Evaluation Example 1 and applying a flame to the samples, the occurrence of holes in the samples was visually observed, and the results are recorded in Table 1 below (○: hole occurred, ×: no hole occurred).

[0100] Evaluation Example 3. Evaluation of Reversibility via XRD Analysis

[0101] The reversibility of the pads prepared in Examples 1 to 2, the pads prepared in Comparative Examples 1 to 5, the adhesive, the aerogel, and the ceramic paper (hereinafter referred to as samples) was evaluated through XRD analysis. Specifically, the samples were placed in a convection oven set to 200°C and heated and maintained for 60 minutes, after which they were cooled from room temperature (approx. 25°C) to an outdoor temperature. The lattice structure of the samples at room temperature before heating and the samples cooled after heating was analyzed using an XRD instrument (D8_Endeavor, Bruker), and the evaluation results are listed in Table 1 below. If there is a change in the XRD pattern before and after heating (evaluated as ○ in Table 1), it can be evaluated as irreversible, and if there is no change in the XRD pattern of the samples before and after heating (evaluated as × in Table 1), it can be evaluated as reversible.

[0102] Evaluation Example 4. Measurement of moisture content

[0103] The moisture content of the pads prepared in Examples 1 and 2, the pads prepared in Comparative Examples 1 to 5, the adhesive, the aerogel, and the ceramic paper (hereinafter referred to as "samples") was measured by Karl-Fisher Oven Titration. The above method involves evaporating moisture from the sample within a chamber using an oven and then measuring the moisture using the Karl-Fisher titration method, and the measurement conditions are as follows. Sample quantity refers to the weight of the sample for which moisture content is to be measured. The Drift Threshold is a criterion for determining whether the titrator has reached a steady state; a Drift Threshold of 20 μg / min means that the experiment was conducted when the background signal generated due to changes in the environment or the instrument during measurement was 20 μg / min or less. Stirrer speed is the stirring speed of the sample in the Karl-Fisher Oven Titration equipment. N2 flow rate means that nitrogen is flowed at a speed of 50 mL / min to push out the moisture from the sample and move it from the oven to the Karl-Fisher titrator. Dry room (-67Td, 22.5℃) means that the dew point temperature of the room where the experiment is conducted is -67℃ and the temperature is 22.5℃. After measuring the moisture content when the chamber temperature was 150℃, 200℃, and 250℃, respectively, the results are listed in Table 1 below.

[0104] - Sample amount: 100 mg

[0105] - Drift Threshold: 20μg / min

[0106] - Stirrer speed: 8

[0107] - N2 flow rate: 50 mL / min

[0108] - Dry room (-67Td, 22.5℃)

[0109] [Table 1]

[0110]

Claims

1. An endothermic pad comprising a binder resin and an endothermic material, wherein the moisture content measured by the Karl Fisher method within a temperature range of 150°C to 250°C per 100 mg of the endothermic pad is 10,000 ppm or more.

2. The heat-absorbing pad according to claim 1, wherein at least one moisture content measured by the Karl Fisher method at temperatures of 150°C, 200°C, and 250°C, respectively, for 100 mg of the heat-absorbing pad is 10,000 ppm or more.

3. The heat-absorbing pad according to claim 1, wherein the moisture content measured by the Karl Fisher method at temperatures of 150°C, 200°C, and 250°C, respectively, for 100 mg of the heat-absorbing pad is 10,000 ppm or more.

4. The heat-absorbing pad according to claim 1, wherein the moisture content measured by the Karl Fisher method within a temperature range of 150°C to 250°C for 100 mg of the heat-absorbing pad is within the range of 10,000 ppm to 300,000 ppm.

5. The heat-absorbing pad according to claim 1, wherein the heat transfer delay temperature of the heat-absorbing pad is 200℃ or lower.

6. The heat-absorbing pad according to claim 1, wherein the XRD pattern of the heat-absorbing pad measured after heating the heat-absorbing pad to 200°C and cooling it to room temperature is different from the XRD pattern of the heat-absorbing pad before heating.

7. The heat-absorbing pad according to claim 1, wherein the heat-absorbing material is a heat-absorbing pad in which the heat-absorbing peak temperature appears at less than 200℃ when the amount of heat absorbed is measured while increasing the temperature from 0℃ to 350℃ at a rate of 10℃ / min using a differential scanning calorimeter.

8. In claim 1, the endothermic substance is H3BO3, HOC(COOH)(CH2COOH)2(NH4)2O·5B2O3·8H2O, Mg(PO4)2·8H2O, MgCl2·6H2O, AlCl3·6H2O, Na4P2O7·10H2O, KAl(SO4)2·12H2O, NiSO4·6H2O, Mg(NO3)2·6H2O, CoSO4·7H2O, (NH4)2Fe(SO4)2·6H2O, CuSO4·5H2O, ZnSO4·7H2O, CoCl2·6H2O, CrCl3·6H2O, NiCl2·6H2O, MgSO4·7H2O, Al2(SO4)3·18H2O, Na2B4O7·10H2O, An endothermic pad comprising one or more selected from the group consisting of Sr(OH)2·8H2O, CaC2O4·H2O, Ba(OH)2·8H2O, Ba(OH)2·H2O, Mg3(PO4)2·5H2O, Mg3(PO4)2·8H2O, and FeSO4·7H2O.

9. In claim 1, the binder resin is a heat-absorbing pad comprising silicone resin.

10. The heat-absorbing pad according to claim 1, wherein the thickness of the heat-absorbing pad is within the range of 0.5 mm to 10 mm.

Images