JP2020132843A - Fire-resistant resin composition, fireproof sheet, and battery - Google Patents

Abstract

To provide a fire-resistant resin composition capable of extinguishing a fire in a short time with respect to firing due to a rapid temperature rise or the like.SOLUTION: A fire-resistant resin composition includes: an endothermic agent in which a start temperature of thermal decomposition is 800°C or below and endotherm is 300 J/g or more; a resin; and a thermal conductive material. A content of the endothermic agent relative to 100 pts.mass of the resin is 10-1,500 pts.mass.SELECTED DRAWING: None

Description

The present invention relates to a refractory resin composition, a refractory sheet made of the refractory resin composition, and a battery including the refractory sheet.

In various batteries typified by lithium batteries, the batteries may run away due to thermal runaway due to an internal short circuit or the like, causing problems such as ignition and smoking. In order to minimize the damage caused by such a defect, a method of making it difficult to transfer the heat of the abnormally high temperature battery to the surrounding battery and the housing containing the battery is being studied. For example, around the battery cell. A method of using a protective material such as a fireproof material or a heat insulating layer can be mentioned.

For example, Patent Document 1 discloses a battery cell in which at least a part of the outside is covered with a fire-resistant coating, and the fire-resistant coating is an ablation coating, an expansion coating, or an endothermic coating. It is disclosed that polyurethane-based coatings can be used.
Further, Patent Document 2 provides a heat insulating layer containing heat-absorbing inorganic compound particles having a thermal conductivity of 0.2 W / m · K or less and having an endothermic peak at a temperature of 80 ° C. or higher, and a binder. A portable electronic device powered by a secondary battery is disclosed.

Special Table 2013-528911 Japanese Patent No. 5643648

By the way, in recent years, batteries of mobile phones and the like have a high battery capacity and are easily ignited due to a rapid temperature rise, and there is a demand for a property of extinguishing a fire in a short time after the ignition. However, although the refractory coating of Patent Document 1 has a property of protecting the battery in the event of ignition, it has not been shown to have a property of extinguishing the fire in a short time. Further, although the heat insulating layer disclosed in Patent Document 2 absorbs heat generated in a battery cell, it has not been shown to have fire resistance.

Therefore, in the present invention, for example, a refractory resin composition capable of extinguishing a fire in a short time against ignition caused by a sudden temperature rise of the battery, a refractory sheet, a battery including the refractory sheet, and an exterior film including the refractory sheet. The challenge is to provide.

The gist of the present invention is as follows [1] to [17].
[1] A resin, a heat absorbing agent having a thermal decomposition start temperature of 800 ° C. or less and an endothermic amount of 300 J / g or more, and a heat conductive substance are contained, and the content of the endothermic agent with respect to 100 parts by mass of the resin is A fireproof resin composition of 10 to 1500 parts by mass.
[2] The refractory resin composition according to [1], wherein the content of the thermally conductive substance with respect to 100 parts by mass of the resin is 10 to 200 parts by mass.
[3] The refractory resin composition according to [1] or [2], wherein the heat absorbing agent has an average particle size of 0.1 to 90 μm.
[4] The refractory resin composition according to any one of [1] to [3], wherein the melt flow rate of the resin is 1.0 g / 10 min or more.
[5] The refractory resin composition according to any one of [1] to [4], wherein the endothermic agent is a metal hydroxide.
[6] The refractory resin composition according to [5], wherein the metal hydroxide is at least one selected from the group consisting of aluminum hydroxide, magnesium hydroxide and calcium hydroxide.
[7] The refractory resin composition according to any one of [1] to [6], wherein the resin is a thermoplastic resin.
[8] The refractory resin composition according to any one of [1] to [7], wherein the endothermic agent has a thermal decomposition start temperature of 500 ° C. or lower and a heat absorption amount of 500 J / g or more.
[9] The refractory resin composition according to any one of [1] to [8] used for a battery.
[10] A refractory sheet comprising the refractory resin composition according to any one of [1] to [9].
[11] The refractory resin composition according to [10], wherein the average thermal conductivity in the plane direction is 0.4 to 80 W / m · K, and the thermal conductivity in the thickness direction is 0.3 to 60 W / m · K. A fireproof sheet made of things.
[12] A refractory sheet made of a refractory resin composition containing a heat absorbing agent, a heat conductive substance, and a resin, wherein the amount of heat absorbed when heated from 23 ° C. to 1000 ° C. is 120 J / g or more. A refractory sheet in which the heat absorption start temperature of the refractory sheet is 800 ° C. or lower.
[13] The refractory resin composition according to [12], wherein the average thermal conductivity in the plane direction is 0.4 to 80 W / m · K, and the thermal conductivity in the thickness direction is 0.3 to 60 W / m · K. A fireproof sheet made of things.
[14] The refractory sheet according to any one of [10] to [13], which has a thickness of 5 to 10000 μm.
[15] A battery comprising the fireproof sheet according to any one of [10] to [14] and a battery cell, and the fireproof sheet is attached to the surface of the battery cell.
[16] An exterior film comprising the fireproof sheet according to any one of [10] to [14].
[17] A base material layer, a metal layer, and a sealant layer are provided in this order, and the fireproof sheet is provided between the base material layer and the metal layer, between the metal layer and the sealant layer, and the base material layer. The exterior film according to the above [16], which is arranged on at least one of the outsides of the above.

According to the present invention, it is possible to provide a refractory resin composition capable of extinguishing a fire in a short time against ignition caused by a sudden temperature rise or the like, a refractory sheet, a battery including the refractory sheet, and an exterior film including the refractory sheet. ..

It is the schematic sectional drawing which shows one Embodiment of the battery which has a square battery cell. FIG. 5 is a schematic cross-sectional view showing another embodiment of a battery having a square battery cell. It is a schematic sectional drawing which shows one Embodiment of the battery which has a laminated type battery cell. FIG. 5 is a schematic cross-sectional view showing an embodiment of a battery having a cylindrical battery cell. It is the schematic sectional drawing which shows one Embodiment of the exterior film. FIG. 5 is a schematic cross-sectional view showing another embodiment of the exterior film.

Hereinafter, the present invention will be described in detail.
[Refractory resin composition]
The fire-resistant resin composition of the present invention contains a resin, an endothermic agent having a thermal decomposition start temperature of 800 ° C. or less and an endothermic amount of 300 J / g or more, and a heat conductive substance, and is said to be said for 100 parts by mass of the resin. The content of the heat absorbing agent is 10 to 1500 parts by mass.
Since the fire-resistant resin composition of the present invention has a heat-absorbing agent having a specific thermal decomposition start temperature and heat absorption amount and a resin in a specific ratio, for example, a battery in which a fire-resistant material made of this fire-resistant resin composition is arranged around. Even if the cell ignites, it can be extinguished quickly. Further, since it contains a heat conductive substance, heat transfer to the heat absorbing material becomes smooth through the heat conductive substance, and fire extinguishing becomes faster.

Further, in the refractory resin composition of the present invention, the average particle size of the endothermic agent is preferably 0.1 to 90 μm, and the melt flow rate of the resin is preferably 1.0 g / 10 min or more. In the present invention, by keeping the average particle size of the endothermic agent and the melt flow rate of the resin within a certain range, the moldability when forming a sheet or the like is improved. When the moldability is good, for example, when a refractory sheet is formed, it can be wound into a roll.

<Resin>
Examples of the resin include a thermoplastic resin and an elastomer resin.
Examples of the thermoplastic resin include polypropylene resins, polyethylene resins, poly (1-) butene resins, polyolefin resins such as polypentene resins, polyester resins such as polyethylene terephthalate, polystyrene resins, acrylonitrile-butadiene-styrene (ABS) resins, and the like. Examples include synthetic resins such as ethylene vinyl acetate copolymer (EVA), polycarbonate resin, polyphenylene ether resin, (meth) acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolak resin, polyurethane resin, and polyisobutylene. Be done.

Elastomer resins include acrylonitrile butadiene rubber, liquid acrylonitrile butadiene rubber, ethylene-propylene-diene rubber (EPDM), liquid ethylene-propylene-diene rubber (liquid EPDM), ethylene-propylene rubber, liquid ethylene-propylene rubber, natural rubber, and liquid natural. Rubber, polybutadiene rubber, liquid polybutadiene rubber, polyisoprene rubber, liquid polyisoprene rubber, styrene-butadiene block copolymer, liquid styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, liquid hydrogenated styrene- Butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, liquid hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene block copolymer, liquid hydrogenated styrene-isoprene block copolymer Examples thereof include coalescence, hydrogenated styrene-isoprene-styrene block copolymer, and liquid hydrogenated styrene-isoprene-styrene block copolymer.
In the present invention, one of these resins may be used alone, or two or more thereof may be mixed and used.

Among the above resins, from the viewpoint of improving moldability, thermoplastic resins such as ethylene vinyl acetate copolymer (EVA), polycarbonate resin, (meth) acrylic resin, polyamide resin, and polyvinyl chloride resin (PVC) are used. Preferably, ethylene vinyl acetate copolymer (EVA) is more preferable.

In the present invention, as described above, the melt flow rate of the resin is preferably 1.0 g / 10 min or more. When the melt flow rate of the resin is 1.0 g / 10 min or more, the dispersibility of the endothermic agent becomes good, the endothermic agent is uniformly dispersed, and good sheet moldability is maintained even if a large amount of the endothermic agent is blended. .. The melt flow rate is more preferably 2.4 g / 10 min or more, further preferably 10 g / 10 min or more, and even more preferably 20 g / 10 min or more. By setting the melt flow rate to these lower limit values or more, the dispersibility of the endothermic agent is improved and it becomes easier to blend a larger amount of the endothermic agent.
The melt flow rate of the resin is preferably 40 g / 10 min or less, more preferably 35 g / 10 min or less.
The melt flow rate was measured according to JIS K 7210-2: 1999 under the conditions of 190 ° C. and a 2.16 kg load.

The content of the resin in the refractory resin composition is preferably 5% by mass or more, more preferably 6% by mass or more, and further preferably 8% by mass or more. When the content of the resin in the refractory resin composition is at least these lower limit values, the moldability when molding the refractory resin composition into the refractory sheet is improved. The content is preferably 85% by mass or less, more preferably 80% by mass or less, still more preferably 50% by mass or less, still more preferably 15% by mass or less. Further, in the present invention, a large amount of the endothermic agent can be blended by setting the upper limit value or less. Further, even with a small amount of resin such as 15% by mass or less, the moldability is improved by adjusting the melt flow rate of the resin and the average particle size of the heat absorbing agent and the heat conductive substance.

<Heat absorber>
In the present invention, as the endothermic agent, one having a thermal decomposition start temperature of 800 ° C. or less and a heat absorption amount of 300 J / g or more is used. If either the thermal decomposition start temperature or the amount of heat absorption is out of the above range, it becomes difficult to extinguish the fire promptly when the battery or the like ignites.
The heat absorbing agent preferably has an average particle size of 0.1 to 90 μm. By setting the average particle size within the above range, the endothermic agent can be easily dispersed in the resin, the endothermic agent can be uniformly dispersed in the resin, and a large amount can be blended.
In the following description, the endothermic agent having a thermal decomposition start temperature of 800 ° C. or less and an endothermic amount of 300 J / g or more is simply referred to as an endothermic agent, but may also be a first endothermic agent.

The thermal decomposition start temperature of the endothermic agent is preferably 500 ° C. or lower, more preferably 400 ° C. or lower, further preferably 300 ° C. or lower, and even more preferably 250 ° C. or lower. By setting the thermal decomposition start temperature of the endothermic agent to these upper limit values or less, the endothermic agent is rapidly decomposed at the time of ignition, and the fire can be extinguished quickly. The thermal decomposition start temperature of the endothermic agent is, for example, 50 ° C. or higher, preferably 100 ° C. or higher, more preferably 150 ° C. or higher, still more preferably 180 ° C. or higher.
The thermal decomposition start temperature can be measured by a thermogravimetric differential thermal analyzer (TG-DTA), and specifically, can be measured by the method described in Examples.

The endothermic amount of the heat absorbing agent is preferably 500 J / g or more, more preferably 600 J / g or more, and further preferably 900 J / g or more. When the heat absorption amount of the heat absorbing agent is within the above range, the heat absorption is improved, so that the fire resistance becomes better. The endothermic amount of the endothermic agent is usually 4000 J / g or less, preferably 3000 J / g or less, and more preferably 2000 J / g or less.
The amount of heat absorbed can be measured using a thermogravimetric differential thermal analyzer (TG-DTA), and specifically, it can be measured by the method described in Examples.

The average particle size of the heat absorbing agent is more preferably 0.5 to 60 μm, further preferably 0.8 to 40 μm, and even more preferably 0.8 to 10 μm. When the average particle size of the endothermic agent is within the above range, the dispersibility of the endothermic agent in the refractory resin composition is improved, the endothermic agent is uniformly dispersed in the resin, and the amount of the endothermic agent blended with the resin is large. Can be done.
The average particle size of the heat absorbing agent is a value of the median diameter (D50) measured by a laser diffraction / scattering type particle size distribution measuring device.

The endothermic agent is not particularly limited as long as it satisfies the above-mentioned thermal decomposition start temperature, heat absorption amount, and average particle size, and examples thereof include metal hydroxides, boron compounds, and hydrates of metal salts. Of these, metal hydroxides are preferable. When a metal hydroxide is used, it is preferable because water is generated by the heat generated by ignition and the fire can be extinguished quickly. Further, a combination of a metal hydroxide compound and a hydrate of a metal salt is also preferable.
Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, hydrotalcite, talcite and the like, and among them, aluminum hydroxide, magnesium hydroxide and calcium hydroxide are preferable. Examples of the boron-based compound include zinc borate and the like. Zinc borate may is hydrate, e.g. _{2ZnO · 3B 2 O 5 · 3.5H} 2 O. Examples of the hydrate of the metal salt include calcium sulfate hydrate (for example, dihydrate), magnesium sulfate hydrate (for example, heptahydrate), kaolin clay, boehmite, dosonite and the like. You may.
Among these, aluminum hydroxide, magnesium hydroxide, and zinc borate are preferable, and aluminum hydroxide and magnesium hydroxide are more preferable.

The content of the endothermic agent in the refractory resin composition is 10 to 1500 parts by mass with respect to 100 parts by mass of the resin. If it is less than 10 parts by mass, the fire cannot be extinguished promptly when the battery or the like ignites. On the other hand, if the amount exceeds 1500 parts by mass, it becomes difficult for the heat absorbing agent to be uniformly dispersed in the resin, and the moldability and the like deteriorate.
The content of the endothermic agent is preferably 100 parts by mass or more, more preferably 500 parts by mass or more, and even more preferably 900 parts by mass or more. Further, it is preferably 1450 parts by mass or less, more preferably 1300 parts by mass or less, and even more preferably 1150 parts by mass or less. By setting the content of the endothermic agent to these lower limit values or more, it is possible to alleviate a rapid temperature rise and to extinguish the fire promptly even if it ignites. Further, when the value is not more than these upper limit values, it becomes easy to disperse uniformly in the resin, and the moldability and the like become excellent.

As a preferred embodiment of the refractory resin composition, as the endothermic agent, a heat absorbing agent having a thermal decomposition start temperature of 500 ° C. or less and a heat absorbing amount of 500 J / g or more is used. By using such an endothermic agent, even if the battery cell ignites, the fire can be extinguished more quickly.

Further, as a preferred embodiment, the refractory resin composition contains, as the endothermic agent, two or more kinds of endothermic agents having different thermal decomposition start temperatures. When two or more endothermic agents having different pyrolysis start temperatures are used, an endothermic reaction is continuously generated in the process of increasing the temperature, and the fire can be effectively extinguished. Further, in a battery, for example, an electrolytic solution is often burned, and the electrolytic solution is burned by ignition or ignition. However, when two or more endothermic agents are contained, the thermal decomposition start temperature corresponding to each flash point and ignition point is set. By using the heat absorbing agent, the fire can be extinguished more effectively.
From the above viewpoint, when the heat absorbing agents contain two or more types having different thermal decomposition start temperatures, the thermal decomposition start temperatures are preferably 50 ° C. or higher and different from each other, and more preferably 70 ° C. or higher.

When two or more types having different pyrolysis start temperatures are included, for example, as one embodiment, an endothermic agent having a pyrolysis start temperature of 250 ° C. or higher (high temperature side heat absorber) and an endothermic agent having a pyrolysis start temperature of less than 250 ° C. (Low temperature side heat absorber) may be used in combination. In this case, the thermal decomposition start temperature of the high temperature side heat absorber is preferably 275 ° C. or higher, and the thermal decomposition start temperature of the low temperature side heat absorber is preferably 225 ° C. or lower. The thermal decomposition start temperature of the high temperature side heat absorber is 800 ° C. or lower, preferably 500 ° C. or lower, more preferably 400 ° C. or lower, and the thermal decomposition start temperature of the low temperature side heat absorber is preferably 110 ° C. or higher, 150 ° C. The above is more preferable. Examples of the high temperature side heat absorbing agent in such an embodiment include magnesium hydroxide, and examples of the low temperature side heat absorbing agent include aluminum hydroxide.

Further, as another embodiment, for example, a heat absorbing agent having a thermal decomposition start temperature of 150 ° C. or higher (high temperature side heat absorbing agent) and a heat absorbing agent having a thermal decomposition starting temperature of less than 150 ° C. (low temperature side heat absorbing agent) are used in combination. It is good to do. In this case, the thermal decomposition start temperature of the high temperature side heat absorber is preferably 175 ° C. or higher, and the thermal decomposition start temperature of the low temperature side heat absorber is preferably 130 ° C. or lower. The thermal decomposition start temperature of the high temperature side heat absorber is 800 ° C. or lower, preferably 500 ° C. or lower, more preferably 250 ° C. or lower, and the thermal decomposition start temperature of the low temperature side heat absorber is preferably 50 ° C. or higher. Examples of the high-temperature side endothermic agent in the present embodiment include aluminum hydroxide, and examples of the low-temperature side endothermic agent include calcium sulfate hydrate and magnesium sulfate hydrate.

As described above, when two or more kinds are used in combination in each embodiment, the hydrate of the low temperature side endothermic metal salt with respect to the content of the high temperature side endothermic agent is not particularly limited, but is 1/9 or more and 9/1 or less. Preferably, it is preferably 2/8 or more and 8/2 or less, and more preferably 3/7 or more and 7/3 or less.

<Thermal conductive material>
The thermally conductive substance refers to a substance having a thermal conductivity of 5 W / m · K or more, and examples thereof include a thermally conductive filler, whiskers, and chopped strands. Of these, a thermally conductive filler is preferable, and examples of the thermally conductive filler include fillers such as graphite, metal, and inorganic compounds.
Examples of the metal filler include aluminum, silver, copper, magnesium, iron, chromium, nickel, titanium, zinc, tin, molybdenum, tungsten, and alloys containing any of these (stainless steel and the like). As the metal filler, silver, copper, aluminum, iron and stainless steel are preferable.
Examples of the inorganic compound filler include metal oxides such as aluminum oxide, magnesium oxide, calcium oxide, magnesium oxide, iron oxide, titanium oxide, tin oxide, antimony oxide and zinc oxide, and nitrides such as boron nitride, aluminum nitride and silicon nitride. , Carbides such as silicon carbide, basic magnesium carbonate, magnesium carbonate, zinc carbonate, strontium carbonate, carbonate compounds such as barium carbonate (however, other than calcium carbonate) and the like. In addition to these, silica, talc, diatomaceous soil, barium sulfate, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, silica-based balloon, graphite, graphene, carbon black, carbon fiber, carbon Examples thereof include balloons, charcoal powder, ferrite, potassium titanate, magnesium sulfate, lead zirconate titanate, zinc stearate, calcium stearate, aluminum borate, molybdenum sulfide, stainless steel fiber, slag fiber, and fly ash.

As the inorganic compound filler, magnesium oxide, aluminum oxide, zinc oxide and boron nitride are preferable, and boron nitride and magnesium oxide are more preferable.
From the viewpoint of facilitating the improvement of thermal conductivity, boron nitride is further considered to be agglomerated particles which are secondary particles in which primary particles of boron nitride are agglomerated, for example, agglomerated particles in which fragile primary particles are agglomerated. preferable.

As the heat conductive filler, one type may be used alone, or two or more types may be mixed and used. Further, these thermally conductive fillers may be surface-treated in order to improve the adhesion to the resin and the workability.

The content of the thermally conductive substance (particularly, the thermally conductive filler) in the refractory resin composition is preferably 10 to 600 parts by mass, more preferably 10 to 550 parts by mass, and 10 to 500 parts by mass with respect to 100 parts by mass of the resin. By mass is even more preferred, and 10 to 200 parts by mass is even more preferred. When the content of the heat conductive filler is within the above range, it becomes easier to improve the heat conductivity.

Thermally conductive material (in particular, the thermally conductive filler) density of, preferably 2.0~8.0g / cm ^3, more preferably 2.0~6.0g / cm ^3, 2.0~5.0g / Cm ³ is more preferred.
The average particle size of the heat conductive substance (particularly, the heat conductive filler) is preferably 0.1 to 200 μm, more preferably 5 to 150 μm, still more preferably 10 to 100 μm.
The method for measuring the average particle size is the same as the method for measuring the average particle size of the heat absorber.
The thermal conductivity of a thermally conductive substance (particularly, a thermally conductive filler) is preferably 5 W / m · K or more, more preferably 10 W / m · K or more, and the upper limit is not particularly limited, but is usually 2000 W / m · K. It is as follows.
The shape of the heat conductive substance (particularly, the heat conductive filler) is not particularly limited, and may be any shape such as a spherical shape, a hollow shape, a plate shape, a fragment shape, and a needle shape, and different shapes may be mixed. It may be agglomerated particles which are secondary particles in which primary particles are agglomerated.

From the viewpoint of efficient heat transfer to the heat absorbing agent, the mass ratio of the heat conductive substance to the heat absorbing agent (heat conductive substance / heat absorbing agent) is preferably 2/98 to 20/80, preferably 5/95. It is preferably ~ 15/85.

<Arbitrary ingredient>
[Heat absorbing agents other than the above-mentioned heat absorbing materials]
In the refractory resin composition of the present invention, in addition to the above-mentioned endothermic agent (first endothermic agent), an endothermic agent having a thermal decomposition start temperature higher than 800 ° C. (hereinafter, also referred to as "second endothermic agent"). May be contained. In this case, as the second endothermic agent, an endothermic agent having a thermal decomposition start temperature higher than 800 ° C. and an endothermic amount of 300 J / g or more is preferable. By using a second endothermic agent having a high thermal decomposition start temperature and a high endothermic amount in combination with the above-mentioned first endothermic agent, for example, after a certain amount of combustion continues, the second endothermic agent Since combustion is suppressed, for example, it is possible to prevent the battery from spreading.
The thermal decomposition start temperature of the second endothermic agent is preferably 1200 ° C. or lower, more preferably 1000 ° C. or lower. By setting these upper limits or less, combustion can be effectively suppressed by the second endothermic agent.
The heat absorption amount of the second endothermic agent is preferably 500 J / g or more, more preferably 600 J / g or more, still more preferably 900 J / g or more, still more preferably 1500 J / g, from the viewpoint of enhancing the combustion suppressing effect. It is g or more. The heat absorption amount of the second endothermic agent is usually 4000 J / g or less, preferably 3000 J / g or less, and more preferably 2000 J / g or less.

Examples of the second heat absorbing agent include metal carbonates such as calcium carbonate, basic magnesium carbonate, magnesium carbonate, zinc carbonate, strontium carbonate, and barium carbonate.
The content of the second endothermic agent is not particularly limited, but the mass ratio (second endothermic agent / first endothermic agent) to the content of the first endothermic agent is 1/9 or more and 7/3 or less. It is preferable, 2/8 or more and 6/4 or less is more preferable. By setting the mass ratio of the contents within the above range, the effect of using the second endothermic agent can be easily exerted.
The average particle size of the second endothermic agent is not particularly limited, but is preferably 0.1 to 90 μm. When the average particle size is within the above range, the moldability is improved. The average particle size of the second endothermic agent is more preferably 0.5 to 60 μm, further preferably 0.8 to 40 μm, and even more preferably 0.8 to 10 μm. The method for measuring the average particle size of the second endothermic agent is as described above.

〔Flame retardants〕
The refractory resin composition of the present invention preferably further contains a flame retardant. When the refractory resin composition of the present invention contains a flame retardant, the spread of fire can be suppressed even when the refractory sheet using the flame retardant is ignited.
Examples of the flame retardant include various phosphate esters such as red phosphorus, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresil diphenyl phosphate, and xylenyl diphenyl phosphate, sodium phosphate, potassium phosphate, and the like. Examples thereof include metal phosphates such as magnesium phosphate, ammonium polyphosphate, and compounds represented by the following general formula (1).

In the general formula (1), R ¹ and R ³ represent hydrogen, a linear or branched alkyl group having 1 to 16 carbon atoms, or an aryl group having 6 to 16 carbon atoms, which are the same or different. R ² represents a hydroxyl group, a linear or branched alkyl group having 1 to 16 carbon atoms, straight-chain or branched alkoxy group having 1 to 16 carbon atoms, an aryl group having 6 to 16 carbon atoms, or carbon atoms It shows 6 to 16 aryloxy groups.

Specific examples of the compound represented by the general formula (1) include methylphosphonate, dimethyl methylphosphonate, diethyl methylphosphonate, ethylphosphonate, n-propylphosphonate, n-butylphosphonate, and 2-methylpropylphosphonate. , T-butylphosphonate, 2,3-dimethyl-butylphosphonate, octylphosphonate, phenylphosphonic acid, dioctylphenylphosphonate, dimethylphosphonate, methylethylphosphinic acid, methylpropylphosphinic acid, diethylphosphonate, dioctylphosphonate , Phosphonate, diethylphenylphosphonate, diphenylphosphonate, bis (4-methoxyphenyl) phosphonate and the like. The flame retardant may be used alone or in combination of two or more.
Among the flame retardants, red phosphorus, ammonium polyphosphate, and the compound represented by the general formula (1) are preferable from the viewpoint of improving the flame retardancy of the fireproof sheet, and the flame retardant performance, safety, cost, and the like are preferable. Ammonium polyphosphate is more preferable from the viewpoint of.

When the refractory resin composition of the present invention contains a flame retardant, the content thereof is preferably 1 to 200 parts by mass, more preferably 5 to 100 parts by mass, and 5 to 50 parts by mass with respect to 100 parts by mass of the resin component. Is more preferable. When the content of the flame retardant is within the above range, the spread of fire can be suppressed when the refractory sheet using the refractory resin composition ignites.

[Thermal expandable graphite]
The refractory resin composition of the present invention may contain heat-expandable graphite. When the refractory resin composition contains heat-expandable graphite, the heat-expandable graphite expands when heated to form a large-capacity void and functions as a flame retardant. Therefore, the refractory resin composition is used for fire resistance. When the sheet is ignited, the spread of fire can be suppressed.

The heat-expandable graphite is not particularly limited as long as it expands when heated, and powders such as natural scaly graphite, pyrolytic graphite, and kiss graphite are treated with an inorganic acid and a strong oxidizing agent to form a graphite intercalation compound. Examples include those produced, which are crystalline compounds that maintain the layered structure of carbon.
Examples of the inorganic acid include concentrated sulfuric acid, nitric acid, selenic acid and the like, and examples of the strong oxidizing agent include concentrated nitric acid, perchloric acid, perchlorate, permanganate, dichromate, hydrogen peroxide and the like. Can be mentioned.
The heat-expandable graphite may be further neutralized. Specifically, it is preferable to further neutralize the heat-expandable graphite obtained by the acid treatment with ammonia, an aliphatic lower amine, an alkali metal compound, an alkaline earth metal compound or the like.
The particle size of the heat-expandable graphite is preferably 20 to 200 mesh. When the particle size of the expandable graphite is within the above range, it expands and easily forms a large-capacity void, so that the flame retardancy is improved. In addition, the dispersibility in the resin is also improved.

The average aspect ratio of the heat-expandable graphite is preferably 2 or more, more preferably 5 or more, and even more preferably 10 or more. The upper limit of the average aspect ratio of the heat-expandable graphite is not particularly limited, but is preferably 1,000 or less from the viewpoint of preventing the heat-expandable graphite from cracking. When the average aspect ratio of the heat-expandable graphite is 2 or more, it expands and easily forms a large-capacity void, so that flame retardancy is improved.
The average aspect ratio of the heat-expandable graphite was measured for each of the 10 heat-expandable graphites in the maximum dimension (major axis) and the minimum dimension (minor axis), and the maximum dimension (major axis) was divided by the minimum dimension (minor axis). Let the average value be the average aspect ratio. The major axis and minor axis of the heat-expandable graphite can be measured using, for example, a field emission scanning electron microscope (FE-SEM).

When the refractory resin composition contains thermally expandable graphite, the content thereof is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, and further 30 to 100 parts by mass with respect to 100 parts by mass of the resin. preferable. When the content of the heat-expandable graphite is within the above range, it becomes easy to form a large-capacity void in the refractory resin composition, so that the flame retardancy is improved.

[Inorganic filler]
The fire-resistant resin composition of the present invention may further contain an inorganic filler other than an endothermic agent, a flame retardant, a heat conductive substance and expansive graphite.
The inorganic filler is not particularly limited, and examples thereof include glass fibers, glass beads, and dehydrated sludge. These inorganic fillers may be used alone or in combination of two or more.

The average particle size of the inorganic filler is preferably 0.5 to 100 μm, more preferably 1 to 50 μm. When the content of the inorganic filler is low, the particle size is preferably small from the viewpoint of improving dispersibility, and when the content is high, the viscosity of the refractory resin composition increases and the moldability becomes higher as the filling progresses. It is preferable that the particle size is large because it decreases.

When the fire-resistant resin composition of the present invention contains an inorganic filler other than a heat absorbing agent, a heat conductive substance and expansive graphite, the content thereof is preferably 10 to 300 parts by mass with respect to 100 parts by mass of the resin. More preferably, it is 10 to 200 parts by mass. When the content of the inorganic filler is within the above range, the mechanical properties of the refractory sheet using the inorganic filler can be improved.

[Plasticizer]
The refractory resin composition of the present invention may further contain a plasticizer. In particular, when the resin component is a polyvinyl chloride resin, it is preferable to include a plasticizer from the viewpoint of improving moldability.
The plasticizer is not particularly limited as long as it is a plasticizer generally used in producing a polyvinyl chloride resin molded product. Specifically, for example, phthalate ester plasticizers such as di-2-ethylhexylphthalate (DOP), dibutylphthalate (DBP), diheptylphthalate (DHP), and diisodecylphthalate (DIDP), di-2-ethylhexyl adipate (di-2-ethylhexyl adipate). DOA), diisobutyl adipate (DIBA), dibutyl adipate (DBA) and other fatty acid ester plasticizers, epoxidized soybean oil and other epoxidized ester plasticizers, adipic acid ester, adipate polyester and other adipic acid ester plasticizers, Tory 2 -Examples include trimellitic acid ester plasticizers such as ethylhexyl trimellitate (TOTM) and triisononyl trimellitate (TINTM), and process oils such as mineral oil. The plasticizer may be used alone or in combination of two or more.
When the refractory resin composition of the present invention contains a plasticizer, the content thereof is preferably 5 to 40 parts by mass, more preferably 5 to 35 parts by mass with respect to 100 parts by mass of the resin. When the content of the plasticizer is within the above range, the extrusion moldability tends to be improved, and it is possible to prevent the molded product from becoming too soft.

<Other ingredients>
The refractory resin composition of the present invention may contain various additive components as necessary, as long as the object of the present invention is not impaired.
The type of this additive component is not particularly limited, and various additives can be used. Examples of such additives include lubricants, shrinkage inhibitors, crystal nucleating agents, colorants (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, antistatic agents, fillers, reinforcing agents, flame retardant aids. , Antistatic agents, surfactants, vulcanizing agents, surface treatment agents and the like. The amount of the additive added can be appropriately selected as long as the moldability and the like are not impaired. The additive may be used alone or in combination of two or more.

<Manufacturing method>
In the fire-resistant resin composition of the present invention, the resin, heat absorbing agent, heat conductive substance, and optional components are mixed using a known device such as a Banbury mixer, a kneader mixer, a kneading roll, a Raikai machine, and a planetary stirrer. Can be obtained by doing.

[Fireproof sheet]
The refractory sheet of the present invention comprises the above refractory resin composition. In the present invention, by using the refractory sheet around the battery or the like, even if the battery or the like ignites, it can absorb heat and quickly extinguish the fire.
The thickness of the refractory sheet is not particularly limited, but is preferably 5 to 10000 μm, more preferably 20 to 4000 μm, further preferably 50 to 2000 μm, further preferably 100 to 1800 μm, and even more preferably 500 to 1500 μm. When the thickness of the refractory sheet is within the above range, it can be used for a small battery cell while maintaining the mechanical strength. The "thickness" of the refractory sheet in the present specification refers to the average thickness of three points in the width direction of the refractory sheet.

The refractory sheet of the present invention may be used as a single refractory sheet, or may be formed by laminating layers other than the refractory sheet to form a refractory multilayer sheet. The refractory multilayer sheet has, for example, a base material and a fireproof sheet provided on at least one surface of the base material.
Here, the base material may be a combustible layer, a semi-incombustible layer, or a non-combustible layer. The thickness of the base material is not particularly limited, but is, for example, 5 μm to 1 mm. Examples of the material used for the flammable layer include one type or two or more types of cloth material, paper material, wood, resin film and the like. When the base material is a semi-incombustible layer or a non-combustible layer, examples of the material used for the semi-incombustible layer or the non-combustible layer include a metal and an inorganic material.

Further, the refractory multilayer sheet may include a refractory sheet and an adhesive layer provided on at least one surface of the refractory sheet. The pressure-sensitive adhesive layer may be provided on the above-mentioned base material, or may be formed directly on the surface of the refractory sheet. Further, a double-sided adhesive tape provided with adhesive layers on both surfaces of the base material may be attached to at least one surface of the refractory sheet. That is, the pressure-sensitive adhesive layer, the base material, and the pressure-sensitive adhesive layer may be provided on one surface of the refractory sheet in this order.
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include, but are not limited to, an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is, for example, 3 to 500 μm, preferably 10 to 200 μm.

In one aspect of the present invention, the refractory sheet is made of a refractory resin composition containing a resin, a heat absorbing agent and a heat conductive substance, and the heat absorbing amount of the refractory sheet is 120 J / g or more. is there. In the present specification, the "heat absorption amount of the refractory sheet" means the heat absorption amount generated when heating from 23 ° C. to 1000 ° C.
If the heat absorption amount of the refractory sheet is less than 120 J / g, it becomes difficult to extinguish the fire promptly when the battery or the like ignites. From the viewpoint of quickly extinguishing the ignition of the battery, the heat absorption amount of the refractory sheet is preferably 120 J / g or more, more preferably 400 J / g or more, and further preferably 700 J / g or more. ..
Further, from the viewpoint of improving the moldability by containing a certain resin in the refractory sheet, the heat absorption amount of the refractory sheet is preferably 2500 J / g or less, more preferably 2000 J / g or less. It is more preferably 1500 J / g or less.
In the present invention, as shown above, the fireproof sheet contains a resin, a heat absorbing agent, and a heat conductive substance, and the amount and type of the heat absorbing agent and the heat conductive substance are appropriately adjusted to absorb the fireproof sheet. The amount of heat can be adjusted within the above range.

The heat absorption start temperature of the refractory sheet is, for example, 800 ° C. or lower. By setting the thermal decomposition start temperature to 800 ° C. or lower, the heat absorption amount of the refractory sheet can be adjusted within a specified range. The heat absorption start temperature of the refractory sheet is preferably 500 ° C. or lower, more preferably 400 ° C. or lower, further preferably 300 ° C. or lower, and even more preferably 250 ° C. or lower. By setting the heat absorption start temperature of the refractory sheet to these upper limit values or less, the refractory sheet is quickly decomposed and absorbs heat at the time of ignition, and the fire can be extinguished quickly.
The heat absorption start temperature of the refractory sheet is, for example, 50 ° C. or higher, preferably 100 ° C. or higher, more preferably 150 ° C. or higher, still more preferably 180 ° C. or higher.

The refractory sheet of the present invention including one aspect of the present invention has an average thermal conductivity of 0.4 to 80 W / m · K in the plane direction and a thermal conductivity of 0.3 to 60 W / m · K in the thickness direction. It is preferably K. Within the above range, heat conduction proceeds evenly in all directions such as the surface direction and the thickness direction, the heat conduction efficiency to the heat absorbing agent is increased, and the fire can be extinguished faster. The average thermal conductivity in the plane direction is more preferably 0.4 to 80 W / m · K. The thermal conductivity in the thickness direction is more preferably 0.3 to 60 W / m · K.
The average thermal conductivity in the plane direction and the thickness direction can be measured by the method described in Examples.

<Manufacturing method of refractory sheet>
The refractory sheet of the present invention can be produced by molding the refractory resin composition of the present invention. Specific examples thereof include extrusion molding, press molding, and injection molding. Among them, extrusion molding is preferable, and molding can be performed using a single-screw extruder, a twin-screw extruder, an injection molding machine, or the like.

[battery]
The refractory sheet of the present invention is preferably used for a battery. A battery typically has at least one battery cell, to which a fireproof sheet may be attached. The refractory sheet is usually attached to the surface of the battery cell. The battery may have one battery cell or two or more batteries.

The battery cell refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, a negative electrode terminal, and the like are housed in an exterior member. Further, the battery cell is classified into a cylindrical type, a square type, and a laminated type according to the shape of the cell.
When the battery cell has a cylindrical shape, it refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, a negative electrode terminal, an insulating material, a safety valve, a gasket, a positive electrode cap, and the like are housed in an outer can. On the other hand, when the battery cell is square, it refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, a negative electrode terminal, an insulating material, a safety valve, and the like are housed in an outer can. When the battery cell is a laminated type, it refers to a constituent unit of a battery in which a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, a negative electrode terminal, and the like are housed in an exterior film. In a laminated battery, between two exterior films, or one exterior film is folded in half, for example, and between the folded exterior films, a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, And the negative electrode terminal and the like are arranged, and the outer edge portion of the exterior film is crimped by heat sealing. Examples of the exterior film include an aluminum film on which a polyethylene terephthalate film is laminated.
The battery cells are lithium-ion batteries, lithium-ion polymer batteries, nickel-hydrogen batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead storage batteries, and air batteries. Etc., and among these, a lithium ion battery is preferable.
Batteries are used, for example, in small electronic devices such as mobile phones and smartphones, notebook computers, automobiles, and the like, but are not limited thereto.

The refractory sheet may be provided on any surface of the battery cell, but preferably covers the surface of most of the battery cell (eg, 50% or more, more preferably 70% or more of the surface area). Since the fireproof sheet covers most of the surface, it is easy to extinguish the fire quickly against the ignition of the battery cell.
Further, the battery cell often has a safety valve, but when it has a safety valve, it is preferable that the battery cell is provided so as to cover the safety valve with a fireproof sheet. At this time, in order to ensure the function of the safety valve, the fireproof sheet may be covered so as not to seal the safety valve. Further, in the case of a laminated type battery cell, it is preferable that the battery cell is provided so as to cover the heat seal portion to be crimped by the heat seal.
Since the battery cell often ignites from the safety valve or the heat seal portion, covering these with a fireproof sheet makes it easier to extinguish the fire more effectively than the ignition of the battery cell.
Further, when the fireproof sheet has a large surface of most of the battery cell and has a safety valve or a heat seal portion, it is more preferable that the fireproof sheet is arranged so as to cover the safety valve or the heat seal portion as well. For example, the refractory sheet may be arranged so as to be wound around the battery cell.

For example, when the battery cell 11 of the battery 10 is square as shown in FIG. 1, the fireproof sheet 12 is arranged so that the outer peripheral surface of the battery cell 11 can be wound around, for example, the main surfaces 11A and 11B thereof and the end surfaces thereof. It is preferably placed on top of 11C, 11D. The main surfaces 11A and 11B are both sides having the largest area in the square battery cell 11, and the end surfaces 11C and 11D are end surfaces connecting the main surfaces 11A and 11B. In a square cell, a safety valve (not shown) is generally provided on either of the end faces 11C and 11D. Therefore, even in the configuration of FIG. 1, the fireproof sheet 11 covers the safety valve of the battery cell 11.
Further, for example, when the battery cell 11 is square as shown in FIG. 2, the refractory sheet 12 may be provided only on both the main surfaces 11A and 11B. Further, it may be provided on only one of the main surfaces 11A and 11B.

When the battery cell 11 is a laminated type, as shown in FIG. 3, the fireproof sheet 12 may be provided so as to cover both sides 11X and 11Y of the battery cell 11, for example. At this time, the fireproof sheet 12 may be arranged so as to cover the heat seal portion 11Z as well. Even in the laminated type, the refractory sheet 12 may be provided so as to cover only one surface 11X. Further, also in the laminated type, the refractory sheet 12 may be arranged so as to wind around the outer peripheral surface of the battery cell 11.
Further, as shown in FIG. 4, when the battery cell 11 is cylindrical, the refractory sheet 12 may be arranged so as to be wound around the outer peripheral surface of the battery cell 11.
In addition, in FIGS. 1 to 4, the refractory sheet 12 may be adhered to the battery cell 11 via an adhesive layer provided on one surface of the refractory sheet 12.
Further, the configurations shown in FIGS. 1 to 4 are merely examples of the arrangement positions of the refractory sheets, and may be arranged at positions other than these.

[Exterior film]
The fireproof sheet of the present invention can be used as an exterior film for a battery cell. Generally, the exterior film is a laminate in which a base material layer, a metal layer, and a sealant layer are laminated in this order, and may further include an adhesive layer for the purpose of enhancing the adhesive strength of each layer.

FIG. 5 shows a cross-sectional view of an embodiment of the exterior film provided with the fireproof sheet of the present invention. The exterior film 20 is an exterior film including a fireproof sheet 24. In addition to the fireproof sheet 24, the exterior film 20 includes a base material layer 21, a metal layer 22, and a sealant layer 23 in this order. Specifically, the base material layer 21, the fireproof sheet 24, the metal layer 22, and the sealant layer 20 are provided. 23 are laminated in this order. The exterior film 20 can be processed into a container by heat-sealing the sealant layers 23 with each other, and accommodates and seals battery cell components such as a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, and a negative electrode terminal. can do. That is, a battery cell using the exterior film 20 as an exterior material can be used.
Since the exterior film 20 includes the fireproof sheet of the present invention, it is possible to extinguish the fire in a short time even if a fire occurs due to an abnormality such as a short circuit of a battery cell. Further, in this case, the fireproof sheet 24 also has a function as an adhesive layer that enhances the adhesive force between the metal layer 22 and the base material layer 21.

In FIG. 5, the fireproof sheet 24 is provided between the base material layer 21 and the metal layer 22, but may be provided between the metal layer 22 and the sealant layer 23, and the base material layer 21 may be provided. It may be provided on the outside of the. Above all, from the viewpoint of improving fire extinguishing property, it is preferable that the fireproof sheet is provided between the base material layer 21 and the metal layer 22 as shown in FIG.

Further, as shown in FIG. 6, an adhesive layer 25 may be provided between the refractory sheet 24 and the metal layer 22. Thereby, the adhesive force between the refractory sheet 24 and the metal layer 22 can be enhanced. The position of the adhesive layer 25 is not limited to this aspect, and may be arranged between any layers constituting the exterior film, and may be provided, for example, between the refractory sheet 24 and the base material 21.

Further, as described above, the exterior film is generally a laminate in which a base material layer, a metal layer, and a sealant layer are laminated in this order, but instead of the base material layer, a fireproof sheet of the present invention is used to withstand fire. It is also possible to obtain an exterior film in which a sheet, a metal layer, and a sealant layer are laminated in this order. In this case as well, an adhesive layer may be provided between any two layers, and for example, the adhesive layer may be provided between the refractory sheet and the metal layer.

(Base material layer)
The material for forming the base material layer 21 is not particularly limited, but a material having an insulating property is preferable. Resin is preferable as the material for forming the base material layer 21, and for example, polyester resin, polyamide resin, epoxy resin, acrylic resin, fluororesin, polyurethane resin, silicon resin, phenol resin, polyetherimide resin, polyimide resin, and the like. Examples thereof include a resin film formed from a mixture of the above. Among these, polyester resin, polyamide resin and the like are preferable.
Examples of the polyester resin include polyethylene terephthalate and polybutylene terephthalate.
Examples of the polyamide resin include nylons such as nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, and nylon 612.
The base material layer 21 is preferably a resin film formed of the above resin, and may be a uniaxially or biaxially stretched stretched film or an unstretched film. Among them, a stretched film is preferable, and a biaxially stretched film is more preferable, from the viewpoint of increasing heat resistance and pinhole resistance. The base material layer may be formed into multiple layers by laminating different materials from the viewpoint of enhancing pinhole resistance.

The thickness of the base material layer is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and further preferably 20 to 70 μm. When the thickness of the base material is at least the above lower limit value, mechanical strength such as pinhole resistance is improved, and when it is at least the above upper limit value, the thickness of the entire exterior film is thinned and the battery cell is lightened. Or it becomes easy to miniaturize.

(Metal layer)
The exterior film of the present invention includes a metal layer. By providing the metal layer, the pinhole resistance of the battery exterior film can be improved, and water vapor, oxygen, light, etc. can be prevented from entering the inside of the battery.
Examples of the material for forming the metal layer include metal foils such as aluminum, stainless steel, and titanium, and aluminum is particularly preferable.
The thickness of the metal layer is not particularly limited, but is, for example, 10 to 200 μm, preferably 20 to 100 μm.

(Adhesive layer)
The adhesive layer 25 is not particularly limited as long as it is possible to bond the layers constituting the exterior film, and known ones can be used without particular limitation.
The adhesive used to form the adhesive layer 25 may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesion mechanism of the adhesive used for forming the adhesive layer is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a thermal pressure type and the like.

The adhesive layer 25 is formed of a resin component a, and the resin component a includes, for example, a polyester resin, a polyether resin, a polyurethane resin, an epoxy resin, a phenol resin, a polyamide resin, a polyolefin resin, or a polyacetic acid. Examples thereof include vinyl-based resins, cellulose-based resins, (meth) acrylic-based resins, polyimide-based resins, urea resins, amino resins, rubbers, silicone-based resins, and ethylene-fluorinated propylene copolymers. These resin components a may be used alone or in combination of two or more.

The thickness of the adhesive layer 25 is not particularly limited, but is, for example, 2 to 50 μm, preferably 3 to 25 μm.

(Sealant layer)
The sealant layer 23 corresponds to the innermost layer, and is a layer in which the sealant layers are heat-welded to each other when the battery cell is assembled to seal the components of the battery cell.
As described above, the sealant layer 23 may be heat-welded to seal the battery element, and the material thereof is not particularly limited. The sealant layer is formed of, for example, a resin component b, and examples of the resin component b include polyolefins and carboxylic acid-modified polyolefins.
Examples of the polyolefin include chain polyolefins and cyclic polyolefins.
Specific examples of the chain polyolefin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene and other polyethylenes, homopolypropylene, and polypropylene block copolymers (for example, propylene and ethylene block copolymers). , Polypropylene such as a random copolymer of polypropylene (for example, a random copolymer of propylene and ethylene), ethylene-butene-propylene tarpolymer and the like. Among these polyolefins, polyethylene and polypropylene are preferable.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin which is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Can be mentioned. Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene, and specifically, cyclic diene such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these cyclic monomers, cyclic alkene is preferable, and norbornene is more preferable.

Examples of the carboxylic acid-modified polyolefin include a carboxylic acid-modified chain polyolefin and a carboxylic acid-modified cyclic polyolefin.
The carboxylic acid-modified chain polyolefin is a polymer modified by block-polymerizing or graft-polymerizing the chain polyolefin with a carboxylic acid. Examples of the carboxylic acid used for modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like.

, Β-Unsaturated carboxylic acid or its anhydride by copolymerization, or by block polymerization or graft polymerization of α, β-unsaturated carboxylic acid or its anhydride with respect to cyclic polyolefin. Is. The same applies to the cyclic polyolefin modified with carboxylic acid. The carboxylic acid used for the modification is the same as that used for the modification of the acid-modified cycloolefin copolymer. The carboxylic acid-modified cyclic polyolefin means that a part of the monomer constituting the cyclic polyolefin is copolymerized in place of α, β-unsaturated carboxylic acid or its anhydride, or α, β with respect to the cyclic polyolefin. -A polymer obtained by block-polymerizing or graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof. The same applies to the cyclic polyolefin modified with carboxylic acid. The carboxylic acid used for the modification is the same as that used for the modification of the chain polyolefin.
Among these, the resin component b is preferably a carboxylic acid-modified chain polyolefin, and more preferably a carboxylic acid-modified polypropylene.

The sealant layer may be formed of one type of resin component b or may be formed of a blend polymer in which two or more types of resin component b are combined. Further, the sealant layer may be formed of only one layer, or may be formed of two or more layers with the same or different resin components.
The thickness of the sealant layer can be appropriately selected, for example, 10 to 100 μm, preferably 15 to 50 μm.

(Making exterior film)
The exterior film of the present invention can be produced by using a heat laminating method, an extrusion molding method, or the like. For example, each layer constituting the exterior film can be prepared and formed into a laminate by a known method such as thermal lamination. Further, among the layers constituting the exterior film, the first laminate in which at least two layers are laminated, and the second layer of the layers constituting the exterior film for a battery other than the layer constituting the first laminate. The exterior film may be produced by preparing a laminate of the above and adhering the two by heat laminating or interposing an adhesive layer.
In the case of forming the first or second laminate, for example, when the fireproof sheet is formed on an arbitrary layer constituting the exterior film such as on the base material layer, the fireproof resin composition is formed on, for example, the base material layer. A diluted solution of the material can be applied and dried to form a refractory sheet. Alternatively, a refractory sheet can be formed by extruding a refractory resin composition onto a base material layer or the like. As yet another method, a refractory sheet prepared in advance may be laminated on a base material layer or the like and heat-laminated.
Further, for example, when the sealant layer is laminated on the metal layer, an extrusion molding method, a thermal laminating method, a gravure coating method, a roll coating method, or the like can be applied.

(Battery cell)
It is preferable to use the above-mentioned exterior film to produce a battery cell using the exterior film as an exterior material. More specifically, it is preferable that the exterior film is used as the exterior material, and at least the positive electrode material, the negative electrode material, the separator, the positive electrode terminal, the negative electrode terminal, and the like are enclosed in the exterior material to form a battery cell. The exterior material is usually formed by heat-sealing the sealant layers of the exterior film, and has a flange portion (a region where the sealant layers are in close contact with each other by the heat seal) on the peripheral edge. Further, normally, the positive electrode terminal and the negative electrode terminal connected to each of the positive electrode and the negative electrode project from the flange portion to the outside.
The battery cell may be either a primary battery or a secondary battery, but is preferably a secondary battery. The type of the secondary battery is not particularly limited, and can be applied to the various secondary batteries described above, and a suitable application target includes a lithium ion battery.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

<Examples 1 to 12, Comparative Examples 1 to 3>
The fire-resistant resin composition containing the resin, heat absorbing agent, heat conductive substance, and flame retardant shown in Tables 1 and 2 was supplied to a uniaxial extruder and extruded at 150 ° C. to a thickness of 1.0 mm. Obtained a fireproof sheet. The following were used as each component.

<Resin>
The following ethylene-vinyl acetate (EVA) resin was used as the resin.
EVA (1): Evaflex EV460, Mitsui DuPont Polychemical Co., Ltd. EVA (2): Evaflex EV150, Mitsui DuPont Polychemical Co., Ltd.

<Heat absorber>
The following compounds were used as heat absorbers.
Aluminum hydroxide: BF013, manufactured by Nippon Light Metal Co., Ltd. Calcium hydroxide: CAOH-2, manufactured by Suzuki Kogyo Co., Ltd. Zinc borate: Firebreak ZB, manufactured by Borax Co., Ltd. Calcium carbonate: Whiten BF-300 Bikita Flourization Co., Ltd.

<Thermal conductive material>
The following thermally conductive filler was used as the thermally conductive substance.
Stainless steel (SUS): Trade name DSR03F, manufactured by Daido Special Steel Co., Ltd., average particle size: 3 μm, density: 7.5 g / cm ³ , thermal conductivity (λ): 16 to 20 W / m · K, spherical magnesium oxide ( MgO): RF-50-SC, manufactured by Ube Material Co., Ltd. Average particle size: 50 μm, density: 3.65 g / cm ³ , thermal conductivity (λ): 42-60 W / m · K, spherical copper (Cu): Product name FMC-SB, manufactured by Furukawa Chemicals Co., Ltd. Average particle size: 1 μm, density: 4.0 g / cm ³ , thermal conductivity (λ): 375-425 W / m · K, spherical boron nitride (BN): PTX60S, Made by Momentive, agglomerate average particle size: 60 μm, density: 2.2 g / cm ³ , thermal conductivity (λ): 30 to 150 W / m · K, fragment-like agglomerate carbon black: trade name carbon black # 20, Made by Mitsubishi Chemical Co., Ltd., average particle size: 50 nm, density: 2.1 g / cm ³ , thermal conductivity (λ): 150-200 W / m · K, spherical

<Flame retardant>
The following compounds were used as flame retardants.
Ammonium polyphosphate: AP422, Clariant AG

<Measurement method of melt flow rate (MFR)>
The melt flow rate was measured according to JIS K 7210-2: 1999 under the conditions of 190 ° C. and 2.16 kg load.
<Measurement method of thermal decomposition start temperature of endothermic agent>
The measurement was performed using a thermogravimetric differential thermal analyzer (TG-DTA). The measurement conditions were from room temperature to 1000 ° C., a heating rate of 4 ° C./min, and an endothermic agent weight of 10 mg. The temperature at which the weight began to decrease from the obtained TG curve was defined as the thermal decomposition start temperature.
<Measurement method of endothermic amount of heat absorber>
Using a thermogravimetric differential thermal analyzer (TG-DTA), the measurement conditions were from room temperature to 1000 ° C., a heating rate of 4 ° C./min, and an endothermic agent weight of 10 mg. The amount of heat absorption (area of the recess) was calculated from the obtained DTA curve.
<Measurement method of average particle size of heat absorber and heat conductive substance>
The average particle size of the heat absorber and the heat conductive substance was measured by a laser diffraction method. Specifically, the average particle size was defined as the particle size at an integrated value of 50% in the particle size distribution obtained by a particle size distribution meter such as a laser diffraction / scattering type particle size distribution meter.

<Measurement method of heat absorption of refractory sheet>
Using a thermogravimetric differential thermal analyzer (TG-DTA), the measurement conditions were from room temperature (23 ° C.) to 1000 ° C., a heating rate of 4 ° C./min, and a refractory sheet weight of 10 mg. The amount of heat absorption (area of the recess) was calculated from the obtained DTA curve.

<Measurement method of endothermic start temperature of refractory sheet>
Using a thermogravimetric differential thermal analyzer (TG-DTA), the measurement conditions were from room temperature (23 ° C.) to 1000 ° C., a heating rate of 4 ° C./min, and a refractory sheet weight of 10 mg. From the obtained DTA curve, the temperature at which the heat absorption amount of the refractory sheet reached 20% was calculated, and the value was used as the heat absorption start temperature of the heat absorption sheet.

<Measurement method of average thermal conductivity>
The average thermal conductivity in the plane direction of the refractory sheet was measured using a Thermowave Analyzer TA manufactured by Hudson Laboratory in the vertical thermal conductivity mode.
Further, the thermal conductivity in the thickness direction of the refractory sheet was measured by setting the thermal conductivity mode in the horizontal direction using a thermowave analyzer TA manufactured by Hudson Laboratory.

<Battery fire extinguishing test>
A fireproof sheet prepared in Examples and Comparative Examples is placed around a laminated lithium-ion battery used in a smartphone, and a test piece is placed on a hot plate set at 400 ° C. to release fire. The time it took for the fire to go out was evaluated. "AA" when the fire extinguishing time is within 3 seconds, "A" when the fire extinguishing time is more than 3 seconds and less than 5 seconds, and "B" when the fire extinguishing time is more than 5 seconds and less than 10 seconds. , When the fire extinguishing time is more than 10 seconds, it is evaluated as "C", and the shorter the fire extinguishing time, the better the fire extinguishing performance. The results are shown in Tables 1 and 2.

<Sheet moldability>
When the sheet was formed into a sheet under the conditions of the above embodiment using a uniaxial extruder, it could be wound with a take-up roll, and when a roll of the sheet was formed, it was "A", and it could not be taken up with a take-up roll. The case where the roll body of the sheet could not be formed was evaluated as "B". The results are shown in Tables 1 and 2.

As is clear from the results of the above examples, according to the present invention, a refractory resin composition capable of extinguishing a fire in a short time against ignition caused by a sudden temperature rise or the like during thermal runaway of a battery cell can be provided. I was able to provide it.

<Example 13>
(1) Preparation of Refractory Sheet A refractory resin composition having the same composition as that used in Example 2 was supplied to a uniaxial extruder and extruded at 150 ° C. to obtain a refractory sheet (thickness 50 μm). ..
(2) Preparation of exterior film (base material layer / fireproof sheet / adhesive layer / metal layer / sealant layer)
The biaxially stretched nylon film (base material layer, thickness 25 μm) and the refractory sheet prepared in (1) above were laminated by thermal lamination to obtain a laminate A of the biaxially stretched nylon film and the refractory sheet. Next, a carboxylic acid-modified polypropylene layer (first sealant layer, thickness 15 μm) and a homopolypropylene layer (second sealant layer, thickness 15 μm) are co-extruded onto one surface of the aluminum foil (metal layer, thickness 40 μm). By doing so, a laminate B in which the metal layer, the carboxylic acid-modified polypropylene layer, and the homopolypropylene layer were laminated in this order was obtained. An adhesive layer composition containing 100 parts by mass of an epoxy resin (phenol novolac type epoxy resin) and 100 parts by mass of an acid anhydride (methylhexahydrophthalic anhydride) is applied to the surface of the metal layer of the laminate B, and the coating is applied. The laminate A was laminated on the adhesive layer composition so that the fireproof sheet was in contact with the adhesive layer composition. After laminating, it was heated to cure the adhesive layer composition to form an adhesive layer (thickness 10 μm) to obtain an exterior film. The exterior film is an exterior film in which a biaxially stretched nylon film (base material layer) / fireproof sheet / adhesive layer / metal layer / carboxylic acid-modified polypropylene layer / homopolypropylene layer are laminated in this order. The obtained exterior film was subjected to a battery fire extinguishing test (2) described later. The results are shown in Table 3.

<Example 14>
(1) Preparation of Fireproof Sheet A fireproof sheet was obtained in the same manner as in Example 13 except that the thickness was set to 40 μm.
(2) Exterior film (base material layer / fireproof sheet / metal layer / sealant layer)
In the same manner as in Example 13, a laminate A of a biaxially stretched nylon film and a fireproof sheet, and a laminate B in which a metal layer, a carboxylic acid-modified polypropylene layer, and a homopolypropylene layer were laminated in this order were obtained. The laminated body A and the laminated body B were laminated by a thermal laminating method to obtain an exterior film. The exterior film is an exterior film in which a biaxially stretched nylon film (base material layer) / fireproof sheet / metal layer / carboxylic acid-modified polypropylene layer / homopolypropylene layer are laminated in this order. The obtained exterior film was subjected to a battery fire extinguishing test (2) described later. The results are shown in Table 3.

<Comparative example 4>
An exterior film was obtained in the same manner as in Example 13 except that the refractory resin composition was changed to that used in Comparative Example 1. The obtained exterior film was subjected to a battery fire extinguishing test (2) described later. The results are shown in Table 3.

<Battery fire extinguishing test (2)>
A battery cell was produced by sealing the components of a battery cell used in a smartphone (including a positive electrode material, a negative electrode material, a separator, a positive electrode terminal, and a negative electrode terminal) with an exterior film manufactured in each Example and Comparative Example. .. Specifically, in a state where the positive electrode terminal and the negative electrode terminal connected to each of the positive electrode material and the negative electrode material are projected outward, the peripheral sealant layers are heat-sealed and sealed to form a battery cell (test piece). Was produced.
The test piece was placed on a hot plate set at 300 ° C., and the time from the release of the fire to the extinguishment of the fire was evaluated according to the following evaluation criteria. The results are shown in Table 3.
AA ... within 1 second A ... over 1 second within 3 seconds B ... over 3 seconds within 5 seconds C ... over 5 seconds

As is clear from the results of Examples 13 and 14 above, it was found that the exterior film provided with the fireproof sheet of the present invention can extinguish a fire in a short time when an abnormality occurs when it is used as an exterior material of a battery cell.

10 Battery 11 Battery cell 12 Fireproof sheet 20 Exterior film 21 Base material layer 22 Metal layer 23 Sealant layer 24 Fireproof sheet 25 Adhesive layer

Claims (17)

It contains a resin, a heat absorbing agent having a thermal decomposition start temperature of 800 ° C. or less and an endothermic amount of 300 J / g or more, and a heat conductive substance, and the content of the heat absorbing agent with respect to 100 parts by mass of the resin is 10 to 1500. A fireproof resin composition which is a mass part. The refractory resin composition according to claim 1, wherein the content of the thermally conductive substance with respect to 100 parts by mass of the resin is 10 to 200 parts by mass. The refractory resin composition according to claim 1 or 2, wherein the heat absorbing agent has an average particle size of 0.1 to 90 μm. The refractory resin composition according to any one of claims 1 to 3, wherein the melt flow rate of the resin is 1.0 g / 10 min or more. The refractory resin composition according to any one of claims 1 to 4, wherein the endothermic agent is a metal hydroxide. The refractory resin composition according to claim 5, wherein the metal hydroxide is at least one selected from the group consisting of aluminum hydroxide, magnesium hydroxide and calcium hydroxide. The refractory resin composition according to any one of claims 1 to 6, wherein the resin is a thermoplastic resin. The refractory resin composition according to any one of claims 1 to 7, wherein the endothermic agent has a thermal decomposition start temperature of 500 ° C. or lower and a heat absorption amount of 500 J / g or more. The refractory resin composition according to any one of claims 1 to 8, which is used for a battery. A refractory sheet comprising the refractory resin composition according to any one of claims 1 to 9. The refractory resin composition according to claim 10, wherein the average thermal conductivity in the plane direction is 0.4 to 80 W / m · K, and the thermal conductivity in the thickness direction is 0.3 to 60 W / m · K. Fireproof sheet. A refractory sheet composed of a refractory resin composition containing a heat absorbing agent, a heat conductive substance, and a resin, wherein the amount of heat absorbed when heated from 23 ° C. to 1000 ° C. is 120 J / g or more.
A refractory sheet in which the heat absorption start temperature of the refractory sheet is 800 ° C. or lower. The refractory resin composition according to claim 12, wherein the average thermal conductivity in the plane direction is 0.4 to 80 W / m · K, and the thermal conductivity in the thickness direction is 0.3 to 60 W / m · K. Fireproof sheet. The fireproof sheet according to any one of claims 10 to 13, which has a thickness of 5 to 10000 μm. A battery comprising the fireproof sheet according to any one of claims 10 to 14 and a battery cell, and the fireproof sheet is attached to the surface of the battery cell. An exterior film comprising the fireproof sheet according to any one of claims 10 to 14. A base material layer, a metal layer, and a sealant layer are provided in this order.
The exterior film according to claim 16, wherein the fireproof sheet is arranged at least between the base material layer and the metal layer, between the metal layer and the sealant layer, and outside the base material layer.