Composite shape

Abstract

This disclosure aims to provide a composite molded article with improved thermal insulation and handling properties. [Solution] A composite molded article containing heat-resistant organic short fibers (1), fibrillated fibers (2), and non-flammable heat-insulating particles (3) is provided.

Description

[Technical Field]

[0001] The present invention relates to composite molded articles, and more particularly to aerogel-fiber composite molded articles. [Background technology]

[0002] Inorganic fibers or non-combustible, flame-resistant organic fibers are used as base materials for thermal insulation in high-temperature environments. Furthermore, aerogels, being porous materials, have low thermal conductivity, making them useful for improving the thermal insulation properties of components, and their use in thermal insulation is attracting attention.

[0003] On the other hand, aerogel itself is very brittle and easily cracked, making it difficult to use on its own. Therefore, its use as an insulating material was being considered in the form of a composite molded body of fibers and aerogel.

[0004] For example, Patent Document 1 describes a method for producing an insulating material that maintains thermal conductivity and is excellent in heat resistance, low dust, tensile strength, and flexibility, comprising: a first step of mixing inorganic fibers and water to obtain a mixture; a second step of making paper from the mixture obtained in the first step to obtain a paper product; and a third step of heating the paper product obtained in the second step to obtain an insulating material, wherein the first step further mixes a polyimide precursor composition containing a polyimide precursor and an aqueous solvent, and / or the second step impregnates the paper product with a polyimide precursor composition containing a polyimide precursor and an aqueous solvent.

[0005] Furthermore, Patent Document 2 describes the density, thickness, and thermal conductivity of a thin-film insulating material containing cellulose fibers and fillers, from the viewpoint of efficiently and inexpensively providing a thin film that achieves both thermal insulation performance and heat resistance as an insulating material that can be installed in a confined space. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-188766 [Patent Document 2] Japanese Patent Publication No. 2019-095046 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, thermal insulation materials have been used in a variety of fields, such as energy storage devices, mobile devices, tools, construction machinery, automobiles, ships, railways, and aircraft. In particular, in fields where thermal runaway, ignition, smoke, explosion, and deterioration can occur due to damage, internal short circuits, or external stresses, there is a need for materials that are both thermally insulating and flame-retardant.

[0008] Aerogel and fiber composites are a very effective means of simultaneously achieving both thermal insulation and flame retardancy. However, there are challenges in efficiently compounding fibers and aerogel, and in providing composites that are flexible, easy to handle, and also have excellent thermal insulation properties. For example, conventional thermal insulation materials described in Patent Document 1 have room for improvement in terms of handling. The thermal insulation material described in Patent Document 2 has excellent handling properties, but there is room for improvement in terms of thermal insulation.

[0009] This disclosure aims to provide a composite molded article with improved thermal insulation and handling properties, in view of the problems associated with conventional thermal insulation materials. [Means for solving the problem]

[0010] One aspect of this disclosure is listed below. <1> The following ingredients: (1) Heat-resistant organic staple fibers; (2) Fibrillated fibers; and (3) Non-combustible adiabatic particles A composite molded article containing the following: <2> The composite molded article according to item 1, comprising oxidized polyacrylonitrile (PAN) fibers as the heat-resistant organic short fibers. <3> The composite molded article according to item 1, comprising 10% or more by dry weight of oxidized polyacrylonitrile (PAN) fibers as the heat-resistant organic short fibers. <4> The composite molded article according to any one of items 1 to 3, wherein the fibrillated fiber includes at least one selected from the group consisting of fibrillated PAN fiber (acrylic pulp), cellulose nanofiber, microfibrillated cellulose, chitin nanofiber, chitosan nanofiber, and aramid pulp. <5> The composite molded article according to any one of items 1 to 4, wherein the fibrillated fiber comprises at least one selected from the group consisting of fibrillated PAN fiber (acrylic pulp), cellulose nanofiber, and microfibrillated cellulose. <6> A composite molded article according to any one of items 1 to 5, comprising aerogel particles having an average particle diameter of 10 μm to 500 μm as the non-combustible heat insulating particles. <7> A composite molded article according to any one of items 1 to 6, wherein the content of the non-combustible heat insulating particles is 10% to 60% by dry weight. <8> A composite molded article according to any one of items 1 to 7, wherein the content of the non-combustible heat insulating particles is 10% to 60% by volume. <9> The composite molded body according to any one of items 1 to 8, wherein the thermal conductivity of the composite molded body is 0.035 W / m·K or less. <10> The composite molded body according to any one of items 1 to 9, wherein the average thickness of the composite molded body is 0.5 mm to 5.0 mm. <11> The composite molded article according to any one of items 1 to 10, wherein the composite molded article is a paper-formed sheet. <12> The following steps: (i) A step of dispersing heat-resistant organic short fibers, fibrillated fibers, and non-flammable insulating particles in a solvent to obtain a dispersion, (ii) The step of removing the solvent from the dispersion by filtration and forming it into a flat film or a three-dimensional shape. A method for manufacturing a composite molded article, including the following: <13> A method for manufacturing the composite body according to item 12, including a step of heating or drying a flat film-like or three-dimensional shaped body at a temperature of 100 °C or higher and lower than 150 °C. <14> A method for manufacturing the composite body according to item 12 or 13, in which a flat film-like or three-dimensional shaped body is obtained by wet papermaking. <15> A method of using a structure including the composite body according to any one of items 1 to 11 as an inter-cell separator for a lithium-ion battery (LiB).

Advantages of the Invention

[0011] According to the present disclosure, a composite body having high heat insulation properties and excellent handling properties such as self-supporting property, flexibility, and work safety can be provided.

Brief Description of the Drawings

[0012] [Figure 1] Scanning electron microscope (SEM) observation photos of the composite body according to one embodiment at magnifications of (a) 100 times and (b) 500 times. [Figure 2] Schematic front view (a) for explaining the measurement of the thermal conductivity of the non-combustible heat insulating particles, and schematic side view (b) with a stainless steel plate fixed. [Figure 3] Schematic diagram for explaining the measurement of the thermal conductivity of the composite body. ​​​​​​​​​​​​​​​​​ <Composite molded body> In one embodiment, the following components: (1) Heat-resistant organic staple fibers; (2) Fibrillated fibers; and (3) Non-combustible adiabatic particles A composite molded article containing the above is provided.

[0017] In this disclosure, a composite molded article means a molded article that is a composite of (1) heat-resistant organic short fibers and (2) fibers such as fibrillated fibers and (3) particles such as non-combustible heat insulating particles.

[0018] By including at least the components described in (1) to (3) above, the composite molded body can have improved thermal insulation and handling properties, and even in the case of a single-layer structure, it can achieve both high thermal insulation and high flame retardancy, excellent handling properties such as self-supporting properties, flexibility and work safety, ease of manufacture, and the ability to create three-dimensional shapes as needed.

[0019] The composite molded article may optionally contain components other than those described in (1) to (3) above.

[0020] Figure 1 shows scanning electron microscope (SEM) images of a composite molded body according to one embodiment at magnifications of (a) 100x and (b) 500x. As shown in Figures 1(a) and (b), the non-combustible insulating particles (3) are dispersed within the framework of the heat-resistant organic short fibers (1). In addition, the morphology of the fibrillated fibers (2) can be clearly observed in Figure 1(b).

[0021] The composite molded article of this disclosure can suppress or prevent the combustion of the fibers forming the skeleton by compounding (3) non-combustible insulating particles with (1) heat-resistant organic short fibers or (2) fibrillated fibers to appropriately encapsulate (3) non-combustible insulating particles. In one example, as shown in Figure 1, the non-combustible insulating particles (3) are contained within the skeleton of the heat-resistant organic short fibers (1), thereby preventing the combustion of the heat-resistant organic short fibers (1) forming the skeleton.

[0022] From the viewpoint of thermal insulation, the thermal conductivity of the composite molded article is preferably 0.035 W / m·K or less, more preferably 0.030 W / m·K or less, even more preferably less than 0.025 W / m·K, and particularly preferably 0.024 W / m·K or less. The thermal conductivity of the composite molded article can be adjusted to 0.035 W / m·K or less by controlling the materials, composition, and physical properties of (1) heat-resistant organic short fibers, (2) fibrillated fibers, and (3) non-combustible thermal insulating particles in, for example, during the manufacturing process.

[0023] From the viewpoint of flame retardancy, the heat resistance temperature of the composite molded article is preferably 500°C or higher. The heat resistance temperature of the composite molded article can be adjusted to within the above range by, for example, dispersing non-combustible heat insulating particles inside the skeleton of heat-resistant organic short fibers, or by applying a flame retardant or non-combustible paint as a component other than those described in (1) to (3) above, as needed.

[0024] The average thickness of the composite molded body is preferably in the range of 0.5 mm to 5.0 mm, more preferably 1.0 mm to 4.0 mm, and even more preferably 1.5 mm to 3.0 mm. As described later, the thermal resistance value of the insulating material is expressed as the value obtained by dividing the thickness of the insulating material by the thermal conductivity, and in practical use, controlling the thermal resistance value is extremely important.

[0025] The thermal resistance value of the composite molded body is 0.04 m 2 It is preferable that the thermal resistance is kW or higher. Thermal resistance is generally expressed as the value obtained by dividing the thickness of the insulating material by the thermal conductivity, as shown in the following formula X. A larger value of this is necessary to prevent heat from flowing from one surface of the insulating material to the other. (Equation X) Introduction of the thermal resistance formula: Thermal resistance = Thickness / Thermal conductivity m 2 K / W In other words, by designing the thickness and thermal conductivity of the composite molded body to arbitrary values, it is possible to control the thermal insulation performance when using the insulation material, and it is preferable to set a thermal resistance value that is suitable for the application. Preferably, the thermal resistance value of the composite molded body is 0.05 m 2It is kW or higher, and more preferably 0.06 m 2 kW or higher, particularly preferably 0.1 m 2 It is kW or higher.

[0026] From the viewpoint of ease of manufacture, ease of molding, and three-dimensional shapeability, the composite molded article is preferably in the form of at least one selected from the group consisting of paper-making sheets, papermaking, woven fabrics, knitted fabrics, nonwoven fabrics (including, for example, felt), and single-layer films, with the form of a paper-making sheet being more preferred, and the form of a wet-machined paper-making sheet or wet-machined paper being even more preferred. Felt is a type of nonwoven fabric in which fibers are intertwined and integrated by processes such as needle punching or columnar flow punching (spunlace) to entangle the fibers.

[0027] • Heat-resistant organic staple fibers The composite molded article of this disclosure contains heat-resistant organic staple fibers as component (1). Here, heat-resistant organic staple fibers refer to organic staple fibers whose melting point, thermal decomposition temperature, and autoignition point are all 200°C or higher. Compared to inorganic fibers, organic fibers have a lower thermal conductivity and, due to their flexibility, are less prone to plastic deformation when compressed. Therefore, when processed onto a nonwoven fabric, they are less likely to be compacted, and solid heat conduction between fibers can be inhibited, thus reducing the thermal conductivity of the composite molded article.

[0028] Heat-resistant organic staple fibers may have a heat-resistant and / or non-flammable backbone. Heat-resistant organic staple fibers may consist of a single type of staple fiber, a combination of multiple types of staple fibers, or a blended yarn of multiple types of staple fibers.

[0029] The term "short fiber" refers to a fibrous material having a fiber length of 20 mm or less, and is typically represented by continuous long fibers cut to a predetermined length, but is not limited by the manufacturing method.

[0030] The material may include one type of heat-resistant organic fiber or a combination of multiple heat-resistant organic staple fibers, and may include or consist of materials known in the art from the viewpoint of composite molding with (2) fibrillated fibers and (3) non-combustible heat-insulating particles, as well as improving heat insulation, flame retardancy and handling. Among the known materials, it is also possible to use a combination of inorganic fibers such as ceramic fibers, carbon fibers, metal fibers, and glass fibers from the viewpoint of heat resistance when used in high-temperature environments. Preferably, the heat-resistant organic staple fiber is oxidized PAN fiber, and by using oxidized PAN fiber, the ease of manufacturing in the manufacturing method described later is high, and because it has the flexibility characteristic of organic fibers, it is excellent in handling and safety when manufacturing or handling the composite molded body.

[0031] In this disclosure, oxidized PAN fibers refer to fibers obtained by heat-treating polyacrylonitrile fibers in an oxidizing atmosphere, for example, in the flame-retardant process, which is the first or upstream step in the carbon fiber manufacturing process.

[0032] Generally, PAN-oxide fibers are non-flammable or infusible in air and are a type of flame-resistant organic fiber. Optionally, PAN-oxide fibers may also possess heat resistance, chemical resistance, flexibility, lightness, a soft texture, and insulation properties.

[0033] Oxidized PAN fibers are given by the following formula (I): [ka] {In the expression, n is an integer greater than or equal to 1.} The structure represented by [formula] exhibits high flame retardancy and fire resistance, and from the viewpoint of further improving flame retardancy and fire resistance, it is more preferable to include this structure as a repeating unit (n≧2 in formula (I)).

[0034] The repeating units of the structure represented by formula (I) above may be included randomly or in blocks in the PAN oxide fibers, or in the polymer structure randomly or in blocks. The PAN oxide fibers containing the repeating units of the structure represented by formula (I) above have a preferred atomic composition (mol%) of 60-65% carbon atoms (C), 1-5% hydrogen atoms (H), 16-24% nitrogen atoms (N), and 10-18% oxygen atoms (O), and a more preferred atomic composition (mol%) of 61-64% C, 2-4% H, 18-22% N, and 12-16% O.

[0035] In addition, as an example of a fiber having repeating units of the structure represented by formula (I) above, oxidized PAN fibers, that is, fibers obtained by cyclizing and / or oxidizing an acrylic resin such as polyacrylonitrile (PAN), and further carbonizing it to a predetermined atomic composition as necessary, other heat-resistant organic staple fibers containing a similar structure can also be used in the present invention.

[0036] Oxidized PAN fibers are electrically nonconductive and can function as electrical insulators even after exposure to heat or direct flame. Furthermore, PAN fibers can exhibit chemical resistance to organic solvents, acids, or bases.

[0037] For example, "PANOX (registered trademark)" can be used as the oxidized PAN fiber.

[0038] In another example, as an oxidized PAN fiber, a blended yarn can be used with "PANOX®" / "Pyromex®" / "ZOLTEK (trade name)" and aramid fibers (e.g., "Technora®", "Kevlar®", "Twaron®", etc.), or they can be used in combination.

[0039] (1) The content of heat-resistant organic short fibers in the composite molded article is preferably in the range of 40% to 80% by dry weight, more preferably 50% to 70% by dry weight, based on the dry weight of the composite molded article, from the viewpoint of achieving both high heat insulation and high flame retardancy, from the viewpoint of excellent handling, and from the viewpoint of balancing ease of manufacture and moldability.

[0040] The specific gravity of the heat-resistant organic short fibers is preferably 1.2 to 1.6, more preferably 1.3 to 1.5, and even more preferably 1.4 ± 0.5, relative to the density of water, considering the lightweight nature of the composite molded product, ease of handling in the manufacturing process, and especially its dispersibility in aqueous solvents.

[0041] Multiple heat-resistant organic staple fibers can be used in combination to improve the thermal insulation and flame retardancy of the composite molded article. When multiple heat-resistant organic staple fibers are used in combination, it is preferable to include at least oxidized PAN fibers as part of the heat-resistant organic staple fibers. Including oxidized PAN fibers can impart thickness and flexibility to the composite molded article, thereby increasing safety during the manufacture or handling of the composite molded article. The content of oxidized PAN fibers is preferably 10% or more by dry weight of the composite molded article, more preferably 20% or more by dry weight, even more preferably 30% or more by dry weight, and particularly preferably 35% or more by dry weight, based on the dry weight of the composite molded article. The upper limit of the content of oxidized PAN fibers can be determined according to the balance between thermal insulation, flame retardancy, ease of manufacture, and moldability, and is not limited, but for example, it may be 80% or less by dry weight, based on the dry weight of the composite molded article.

[0042] • Fibrillated fiber The composite molded article of this disclosure contains fibrillated fibers as component (2).

[0043] Fibrillated fibers are fibers that have split axially, subdivided, and become fuzzy. Fibrillated fibers can be broadly classified into two types: those produced by physically or chemically destroying the structure of fibers without a branched structure, and those produced by intentionally creating fluffiness during the spinning of polymer compounds. Examples of the former include microfibrillated cellulose (cellulose fibers that have been micronized using at least one physical or chemical means, synonymous with common names such as CNF, CeNF, cellulose nanofiber, MFC, cellulose microfiber, and microfibrous cellulose), acrylic pulp (fibrillated polyacrylonitrile fibers, also called fibrillated PAN fibers), synthetic pulps such as aramid pulp, chitin nanofibers, chitosan nanofibers, and silk nanofibers. Examples of the latter include synthetic pulps produced by flash spinning. Generally, due to their manufacturing method, fibrillated fibers have a structure in which the fiber diameter is partially thinner compared to ordinary fibers without a branched structure. As a result, fibrillated fibers tend to have a large surface area and, at the same time, a large number of bent structures. Due to these characteristics, in composite molded articles, fibrillated fibers have the effect of a binder, binding other fibers, such as heat-resistant organic short fibers, together through physical entanglement. Therefore, as fibrillated fibers, fibrillated binder fibers or fibrillated aqueous binder fibers can be used.

[0044] Among the fibrillated fibers exemplified above, at least one selected from the group consisting of fibrillated PAN fibers (acrylic pulp), cellulose nanofibers, microfibrillated cellulose, chitin nanofibers, chitosan nanofibers, and aramid pulp is preferred from the viewpoint of achieving both high thermal insulation and high flame retardancy, and improving thermal insulation and flame retardancy, and at least one selected from the group consisting of fibrillated PAN fibers (acrylic pulp), cellulose nanofibers, and microfibrillated cellulose is more preferred.

[0045] The fibrillation rate of the fibrillated fibers in the composite molded article is preferably 0.3% or higher. Here, the fibrillation rate refers to the ratio of the total length of branched fibers to the length of the main stem of the fibrillated fiber. Within this range, a sufficient binder effect is obtained, and the shedding of fibers and particles from the composite molded article is reduced. The fibrillation rate of the fibrillated fibers is more preferably 0.5% or higher, even more preferably 0.9% or higher, particularly preferably 1.1% or higher, exceptionally preferably 1.7% or higher, and most preferably 2.2% or higher. There is no particular upper limit to the fibrillation rate, and it may be 100% or less.

[0046] The average fiber length of the fibrillated fibers in the composite molded article is preferably 20 μm or more. Within this range, sufficient binder effect can be obtained. Furthermore, the longer the average fiber length of the fibrillated fibers, the easier it is for the fibrillated fibers to crosslink with other fibers. This crosslinking of fibrillated fibers increases the rigidity of the composite molded article, such as a nonwoven fabric, acting as a binder. Therefore, the more crosslinked fibrillated fibers there are, the greater the rigidity of the composite molded article. Also, fibrillated fibers that do not crosslink will exist in a manner that clings to the outer surface of other fibers and other constituent components. The average fiber length of the fibrillated fibers is more preferably 25 μm or more, and even more preferably 40 μm or more. As an upper limit for the average fiber length, a length of 200 μm or less is preferable because it allows for excellent mixability with other fibers and a uniform molded article can be obtained. Furthermore, in the manufacturing process of fibrillated fibers, the average fiber diameter increases as the average fiber length increases, but if the average fiber diameter is large, the entanglement between fibrillated fibers weakens, and the binder effect decreases. The upper limit of the average fiber length of the fibrillated fibers is more preferably 150 μm or less, even more preferably 100 μm or less, particularly preferably 90 μm or less, especially preferably 60 μm or less, and most preferably 55 μm or less.

[0047] The area fineness ratio of fibrillated fibers in the composite molded article is preferably 2.0% or more. Here, fine fibers refer to fibers with a fiber length of less than 100 μm, and the area fineness ratio is the ratio of the total area of ​​the observed images of fine fibers with a fiber length of less than 100 μm to the total area of ​​the observed images of all fibers (area of ​​normal fibers + area of ​​fine fibers). As mentioned above, in the manufacturing process of fibrillated fibers, the average fiber diameter increases as the average fiber length increases, but if the average fiber diameter is large, the entanglement between fibrillated fibers weakens, and the effect as a binder also decreases. If the area fineness ratio is within this range, a sufficient effect as a binder is obtained, and the shedding of fibers from the composite molded article is reduced. The area fineness ratio is more preferably 3.0% or more, even more preferably 8.0% or more, particularly preferably 27.0% or more, and most preferably 30.0% or more. Furthermore, the presence of ordinary fibers with a fiber length of 100 μm or more allows the fine fibers to form entanglements with the ordinary fibers as the main axis; therefore, it is desirable to include a certain amount of ordinary fibers. For this reason, the upper limit of the area fine fiber ratio is preferably 90.0% or less, more preferably 50.0% or less, and even more preferably 40.0% or less. The advantage of adjusting the area fine fiber ratio within the above range is particularly pronounced when the composite molded product is a nonwoven fabric.

[0048] The average fiber diameter of the fibrillated fibers in the composite molded body is preferably 50 μm or less. This range is preferable because it allows for sufficiently small pore sizes to form within the composite molded body, thereby inhibiting heat transfer by air convection. More preferably, the average fiber diameter of the fibrillated fibers is 20 μm or less, even more preferably 15 μm or less, and most preferably 13 μm or less. The lower limit may be 1.5 μm or more, depending on the resolution of the apparatus. Furthermore, from the viewpoint of drainage in the wet papermaking method and the pulp molding method, the lower limit is preferably 2.5 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more.

[0049] In one example, it is preferable that the composite molded article contains (2) microfibrillated cellulose as fibrillated fibers. As raw materials for this microfibrillated cellulose, examples of so-called wood pulp such as coniferous pulp and hardwood pulp, and non-wood pulp can be used as raw materials for type I cellulose. Examples of raw materials for coniferous pulp include fir, hemlock, Himalayan cedar, larch, spruce, Japanese red pine, Japanese red pine, Japanese black pine, Japanese white pine, longleaf pine, spruce, cypress, sawara cypress, Japanese cedar, metasequoia, Japanese yew, Japanese umbrella pine, Japanese juniper, goldcrest, and blue ice. Examples of raw materials for hardwood pulp include eucalyptus, poplar, Japanese oak, oak, birch, beech, maple, chestnut, paulownia, birch, elm, and aspen. Examples of non-wood pulps include cotton-derived pulps such as cotton linter pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp. Cotton-derived pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp refer to refined pulps obtained from raw materials such as cotton lint or cotton linter, hemp-based abaca (for example, often from Ecuador or the Philippines), zaisal, bagasse, kenaf, bamboo, and straw through a purification process aimed at deligninization by pulping and removal of hemicellulose, as well as a bleaching process. In addition, refined products such as cellulose derived from bacteria such as acetic acid bacteria, cellulose derived from seaweed, and ascidian cellulose can also be used as raw materials for cellulose microfibers. As raw materials for type II cellulose, cut yarns of regenerated cellulose fibers (rayon, lyocell, Bemberg, etc.) and cut yarns of cellulose derivative fibers, or pulp can also be used as raw materials for cellulose microfibers. Furthermore, cut yarns of ultrafine regenerated cellulose or cellulose derivatives obtained by electrospinning can also be used as raw materials for cellulose microfibers or as cellulose microfibers themselves. These raw materials may be used individually or in mixtures of two or more. The average fiber diameter can be adjusted by mixing multiple raw materials.

[0050] The crystalline form of cellulose is not unique; it has various crystalline forms and is broadly classified into type I and type II cellulose. Of these two, type I crystals exhibit high values ​​in terms of rigidity and thermal properties. From the viewpoint of rigidity, it is preferable that the crystalline form of fibrillated fiber cellulose also includes type I crystals. To be precise academically, type I cellulose crystals include two types, Iα and Iβ, but the mixing ratio of Iα and Iβ does not need to be considered here. Also, the higher the proportion of crystalline components (degree of crystallinity) in the cellulose, the greater the rigidity of the microfibrillated cellulose. The degree of crystallinity is preferably 60% or more, and may be 100% or less. More preferably, the degree of crystallinity is 70% or more, even more preferably 80% or more, particularly preferably 85% or more, and most preferably 90% or more. The degree of crystallinity is determined by X-ray diffraction, where diffraction lines from crystalline material are detected as peaks, and scattered light from amorphous material is detected as halos. By fitting these peaks and halos, the following formula is obtained: Crystallinity [%]=100×Ic / (Ic+Ia) The degree of crystallinity can be calculated by substituting {Ic: integrated scattering intensity of the peak, Ia: integrated scattering intensity of the halo} into the formula.

[0051] Microfibrillated cellulose can be obtained by micronizing the raw materials described above. In this disclosure, "micronization" means controlling the fiber length, fiber diameter, fibrillation rate, etc., while reducing the size of the cellulose. In one embodiment, a pretreatment step may be performed before the micronization process. In the pretreatment step, it is effective to prepare the raw material pulp to a state that is easy to micronize by autoclaving under water impregnation at a temperature of 100°C to 150°C, enzymatic treatment, or a combination thereof. These pretreatments not only reduce the burden of the micronization process, but also have the effect of discharging impurities such as lignin and hemicellulose present on the surface and in the gaps of the microfibrils that make up the cellulose fibers into the aqueous phase, thereby increasing the α-cellulose purity of the micronized fibers, and can be effective in improving the heat resistance of microfibrillated cellulose.

[0052] In the pulping process, the raw pulp is dispersed in water and then pulverized using known pulping equipment such as beaters, single-disc refiners, double-disc refiners, and high-pressure homogenizers. The optimal treatment concentration for pulping varies depending on the equipment used and can be set arbitrarily.

[0053] When cellulose is refined in multiple stages, it is effective to combine two or more refinement devices with different refinement mechanisms or shear rates. Here, as a method of multi-stage refinement, it is preferable to refine in multiple stages using disc refiners with different disk configurations, or to refine in a high-pressure homogenizer after refinement in a disc refiner. Here, either a single disc refiner or a double disc refiner may be used.

[0054] When performing multi-stage refinement using multiple disc refiners, it is preferable to use refiners having at least two different disc configurations. By using refiners with different disc configurations, it is possible to control various shape parameters of microfibrillated cellulose, namely the fibrillation rate, average fiber length, and average fiber diameter.

[0055] Adjusting the disc structure of a disc refiner is an effective means of controlling various shape parameters of microfibrillated cellulose. Important structural features of the disc refiner include blade width, groove width, and the blade-to-groove ratio (blade width divided by groove width). Of these, the blade-to-groove ratio is particularly important for producing fibrillated fibers. A small blade-to-groove ratio results in a greater fiber-cutting action, leading to shorter fiber lengths. A large blade-to-groove ratio results in a greater fiber-crushing (beating) action, leading to a higher fibrillation rate. From the viewpoint of fibrillated fiber content in the composite molded article, a blade-to-groove ratio of 0.2 or higher is preferable, 0.4 or higher is more preferable, and 0.5 or higher is most preferable. Furthermore, if the blade-to-groove ratio is constant, smaller absolute values ​​for blade width and groove width result in finer and more uniform microfibrillated cellulose.

[0056] In disc refiners, controlling the distance between the two discs (rotating blade and stationary blade) (hereinafter referred to as "inter-blade distance") is also important. By controlling the inter-blade distance, it is possible to control the average fiber length of microfibrillated cellulose; the smaller the inter-blade distance, the smaller the average fiber length. In the initial processing stage, it is preferable to set the inter-blade distance to 0.05 mm or more and 2.0 mm or less, and in the subsequent processing stage, it is preferable to set the inter-blade distance to 0.05 mm or more and 1.0 mm or less. When adjusting the inter-blade distance, it is preferable to gradually narrow it from a wider inter-blade distance to the desired distance. By controlling it in this way, clogging and overload of the equipment can be prevented, and highly homogeneous microfibrillated cellulose with a narrow distribution of fiber length and fiber diameter can be obtained.

[0057] The degree of refinement can also be controlled by the number of times the cellulose passes through the disc portion (hereinafter referred to as "number of passes"). By increasing the number of passes, cellulose fibers with a uniform distribution of fiber diameter and fiber length can be obtained. In this disclosure, "number of passes" means the number of times the refiner treatment is performed after the blade distance has been set to the desired value. Preferably, the number of passes for the disc refiner is 5 or more, more preferably 20 or more, and even more preferably 40 or more. A higher number of passes is preferable because the distribution of fiber shape gradually converges to a constant value as the number of passes increases, but considering productivity, the upper limit of the number of passes is 300 or less.

[0058] Methods for controlling the number of passes include using one tank for one refiner and simply circulating the slurry, controlling the number of passes based on the flow rate, or using two tanks for one refiner and reciprocating the slurry between the tanks during the refiner process. The former allows for simplification of the equipment. On the other hand, in the latter case, since the cellulose reliably passes through the disc section in each process, a more uniform microfibrillated cellulose can be obtained.

[0059] Another preferred method is to further refine the cellulose fibers, which have been refined by a disc refiner, using a high-pressure homogenizer. Compared to a disc refiner, a high-pressure homogenizer is more effective at thinning the fibers, and by combining it with refinement by a disc refiner, it is possible to obtain elongated microfibrillated cellulose.

[0060] In one example, it is preferable that the composite molded article contains synthetic pulp as (2) fibrillated fibers. Synthetic pulp can be obtained by methods such as spinning and drawing of pre-existing polymers, flash spinning from a solution or emulsion, strip fiber method by uniaxial stretching of a film, or shear polymerization in which monomers are polymerized under shear stress. In addition, BiPUL (registered trademark, manufactured by Nippon Exlan Industries Co., Ltd.) can be used as acrylic pulp, and Kevlar (registered trademark, manufactured by DuPont) or Tiara (registered trademark, manufactured by Daicel Mirise Co., Ltd.) can be used as aramid pulp. It can also be produced by high-pressure homogenization treatment, similar to finely milled cellulose.

[0061] The content of (2) fibrillated fibers in the composite molded article is preferably in the range of 1% to 16% by dry weight, more preferably 2% to 12% by dry weight, based on the dry weight of the composite molded article, from the viewpoint of achieving both high heat insulation and high flame retardancy, as well as balancing ease of manufacture and moldability.

[0062] • Non-combustible insulating particles The composite molded article of this disclosure contains non-combustible heat insulating particles as component (3). Non-combustible heat insulating particles are particles that possess both non-combustibility and heat insulating properties, and can impart extremely excellent heat insulating properties to the composite molded article with components (1) and (2). The composite molded article may contain a single type of non-combustible heat insulating particle, or a combination of multiple types of non-combustible heat insulating particles.

[0063] From the viewpoint of imparting extremely excellent heat insulation properties to the composite molded body, the thermal conductivity of the non-combustible heat insulating particles is preferably in the range of 0.010 W / m·K to 0.026 W / m·K, and more preferably in the range of 0.01 W / m·K to 0.020 W / m·K.

[0064] From the viewpoint of balancing heat insulation, flame retardancy, and ease of manufacture, the average particle size of the non-combustible insulating particles is preferably between 10 μm and 500 μm.

[0065] The density of the non-combustible insulating particles is set at 50 kg / m³, considering the balance between insulating properties, flame retardancy, handling ease, and ease of manufacture. 3 ~200kg / m 3 It is preferable that this be the case.

[0066] Examples of non-combustible insulating particles include, but are not limited to, inorganic particles, organic particles, or combinations thereof, which are known as "insulating particles," and aerogels. Among these, aerogels are preferred from the viewpoint of achieving both high non-combustibility and high insulating properties, and aerogel particles with an average particle diameter of 10 μm to 500 μm are more preferred.

[0067] The thermal insulation particles are not particularly limited as long as they can impart thermal insulation and non-combustibility to the composite molded article; for example, they may be hollow particles or non-hollow particles. Inorganic thermal insulation particles may include, for example, glass, silica particles, etc.

[0068] Organic thermal insulation particles may include polymer thermal insulation particles such as styrene-based resins like cross-linked styrene-acrylic resin, acrylic-based resins like acrylonitrile-acrylic resin, methacrylic resins, phenolic resins, fluororesins, polyamide resins, polyimide resins, polycarbonate resins, and polyether resins.

[0069] In this disclosure, "aerogel" is not limited to the manufacturing method, but refers to a general term for foams having thermal insulation properties greater than those of still air, specifically a thermal conductivity of 0.026 W / m·K or less.

[0070] According to this disclosure, aerogel has been found to exhibit excellent thermal insulation properties in composite molded bodies from the standpoint of convective heat transfer, conductive heat transfer, and radiative heat transfer, although we do not wish to be bound by theory.

[0071] With respect to convective heat transfer, aerogels tend to provide good insulation because their mean free path is smaller than, for example, the mean free path of the molecules that make up the air used as a medium.

[0072] For conductive heat transfer, for example, when the medium is solid and silica aerogel is used as the aerogel, its thermal conductivity is significantly low, making it easier to insulate.

[0073] With respect to radiative heat transfer, the thermal insulation properties can vary depending on the material of the aerogel. For example, aerogels that can absorb infrared radiation as a medium tend to provide better insulation.

[0074] Aerogels can be obtained by known manufacturing methods. As an example, the manufacturing method, classification, and uses of silica aerogels using tetraethoxysilane (TEOS) are described below.

[0075] TEOS is mixed with a solvent such as water, methanol, or ethanol, and optionally an acid catalyst, and hydrolyzed (solified). Then, a base catalyst is added to the hydrolyzate to dehydrate (or alcohol) condensate (gelled) and obtain a gel. The obtained gel is then subjected to solvent replacement to evaporate / dry the liquid medium inside the gel, thereby obtaining a monolithic, granular, powdery, or film-like aerogel. Drying methods include supercritical drying and non-supercritical drying (e.g., atmospheric pressure drying, freeze-drying, etc.). The granular or powdery aerogel can be used as (3) non-flammable insulating particles in this disclosure.

[0076] Monolithic aerogels can be used in a variety of applications, such as building materials, although this is not limited to them. Film-like aerogels can be used in a variety of applications, such as insulation for windows, although this is not limited to them.

[0077] The granular or powdered aerogel can, for example, be used as (3) non-flammable insulating particles, or dispersed in a paint to be used as an insulating paint.

[0078] Alternatively, a base catalyst can be added to the above hydrolysate to dehydrate (or alcohol) condensate (gel) it, and then the resulting gel can be composite-molded with components (1) and (2) of this disclosure to obtain a fibrous substrate. The obtained fibrous substrate can be used, but is not limited to, for example, as insulation for building materials or piping, or as inter-cell insulation for batteries.

[0079] Alternatively, a base catalyst can be added to the above hydrolysate to cause dehydration (or alcohol) condensation (gelation), and the resulting gel can be mixed with components (1) and (2) of the present disclosure, and then the solvent can be replaced and dried to form an insulating material for building materials or piping, or an insulating material between battery cells.

[0080] This material exhibits extremely low thermal conductivity due to its unique combination of fibrillated fibers and non-combustible insulating particles. While we do not wish to be constrained by theory, generally speaking, composite materials consisting of non-combustible insulating particles and fibers can be considered porous materials with continuous pores, and therefore their thermal conductivity does not decrease as easily as that of closed-cell insulating materials. However, in the composite molded article according to this embodiment, the fibrillated fibers act as a ventilation-inhibiting film in any layer within the composite, resulting in almost no heat transfer by convection in the thickness direction. In addition, the non-combustible insulating particles uniformly dispersed in the structure exhibit extremely high thermal insulation in both the thickness direction and the planar direction. As a result, it exhibits extremely low thermal conductivity with a small aerogel content compared to similar composite materials.

[0081] Therefore, the content of (3) non-combustible heat insulating particles in the composite molded article is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, based on the volume of the composite molded article, from the viewpoint of improving heat insulation and flame retardancy. On the other hand, from the viewpoint of exhibiting sufficient heat insulation while balancing handling, ease of manufacture, moldability, etc., it is preferably 70% by volume or less, more preferably 60% by volume or less, and even more preferably within the range of 50% by volume or less.

[0082] Similarly, the content of (3) non-combustible heat insulating particles in the composite molded article is preferably 10% by dry weight or more, more preferably 15% by dry weight or more, even more preferably 25% by dry weight or more, and particularly preferably 30% by dry weight or more, based on the dry weight of the composite molded article, from the viewpoint of improving heat insulation and flame retardancy. On the other hand, from the viewpoint of exhibiting sufficient heat insulation while balancing handling, ease of manufacture, and moldability, the upper limit of the content is preferably 60% by dry weight or less. It is more preferably within the range of 50% by dry weight, and even more preferably 45% by dry weight or less.

[0083] • Additional elements The composite molded article may optionally contain additional elements other than components (1) to (3). These additional elements may include fibers that do not fall under either component (1) or component (2), such as non-heat-resistant fibers, heat-resistant long fibers, non-fibrillated fibers, etc.; fiber dispersants; papermaking adhesives; binders; crosslinking agents; and residues derived from the manufacturing process.

[0084] From the viewpoint of achieving both high thermal insulation and high flame retardancy, it is preferable that the composite molded body does not contain thermally conductive particles.

[0085] <Method for manufacturing composite molded articles> In another embodiment, a method for manufacturing a composite molded article is provided. The method for manufacturing a composite molded article includes, for example, the following steps: (i) A step of dispersing heat-resistant organic short fibers, fibrillated fibers, and non-flammable insulating particles in a solvent to obtain a dispersion, (ii) The step of removing the solvent from the dispersion by filtration and forming it into a flat film or a three-dimensional shape. It can include...

[0086] According to the method for manufacturing a composite molded article, which includes steps (i) and (ii) described above, a flat film-like or three-dimensional composite molded article having high heat insulation and high flame retardancy can be easily manufactured.

[0087] The components of the composite molded article described above can be used as various materials for use in the manufacturing method of the composite molded article of this disclosure.

[0088] The solvent used in the method for producing the composite molded article of this disclosure is not particularly limited, and known liquid media such as water or organic solvents can be used. Water is preferred considering ease of handling and environmental impact, but a non-polar organic solvent with lower surface tension may be used to control the thickness and density of the composite molded article. When water is used as the liquid medium, a surfactant may be added to control the surface tension.

[0089] From the viewpoint of improving the thermal insulation and flame retardancy of the composite molded article, the method for manufacturing the composite molded article preferably includes a step of heating or drying a flat film-like or three-dimensional molded article at a temperature of 100°C or higher but less than 150°C.

[0090] By adding fiber dispersants, binders, and crosslinking agents as additives during molding, it is possible to control the strength, handling properties such as fiber shedding, and structural properties such as internal uniformity and surface smoothness of the composite molded product. These additives may be used individually or in combination of two or more types.

[0091] Fiber dispersants include surfactants that facilitate the defibrillation of bundled fibers in a liquid medium, and viscous agents that adjust the viscosity of the liquid medium and prevent fiber aggregation. These agents enable improved smoothness and homogeneity of the molded surface, as well as control of the air permeability resistance per unit thickness by homogenizing the internal structure.

[0092] The added surfactants can also affect the surface tension of the liquid medium. Binders refer to adhesive components such as starch, which can bond fibers together, thereby controlling the structural strength and air permeability resistance per unit thickness. Crosslinking agents refer to isocyanates, polyurethanes, etc., which can prevent fiber shedding and adjust strength by chemically or physically crosslinking the entanglement points of fibers.

[0093] When using materials with hydrophilic functional groups such as hydroxyl groups, carbonyl groups, carboxyl groups, and amino groups as fibers, such as heat-resistant organic staple fibers and fibrillated fibers, repeated absorption and dehumidification of moisture from the air may cause the fibers to aggregate, altering their microstructure. In such cases, it is possible to stop this fiber movement and suppress aggregation by constraining the fibers with a crosslinking agent.

[0094] Specifically, the wet papermaking method and the pulp molding method are preferred as molding methods according to this disclosure, since they allow for processing into any shape. The wet papermaking method tends to easily yield two-dimensional planar or flat film-shaped molded articles (which can also be called nonwoven fabrics). On the other hand, the pulp molding method makes it possible to create complex three-dimensional shapes. From the viewpoint of balancing thermal insulation, flame retardancy, ease of manufacture, and moldability, it is more preferable that flat film-shaped or three-dimensional molded articles be obtained by the wet papermaking method.

[0095] As an example, a method for manufacturing a flat-film-shaped composite molded body is shown below. A method for manufacturing a flat-film composite molded body includes, for example, the following steps: (a) Dispersing oxidized PAN fibers and cellulose nanofibers in a medium such as water using a fiber dispersant to form a first dispersion; (b) Adding aerogel particles to the first dispersion and further dispersing them to form a second dispersion; (c) Add a papermaking viscous agent to the second dispersion and stir to form a dispersion; (d) The step of forming a paper body by papermaking the dispersion into a flat film using a suction filter; and (e) The step of drying the papered body in a drum dryer; It can include...

[0096] Step (c) described above is advantageous in terms of suppressing the levitation of aerogel particles.

[0097] Step (e) above can be carried out by drying the papermaking body with a drum dryer or the like.

[0098] As another example, the method for manufacturing a composite molded article according to the present disclosure makes it possible to easily manufacture a composite molded article having high thermal insulation and high flame retardancy, as well as a three-dimensional structure. A three-dimensional structure means that the composite molded article is not a two-dimensional (planar or flat) structure, but has at least one curved structure, and is hereinafter also referred to as "three-dimensional" or "three-dimensional structure".

[0099] Composite molded articles having a three-dimensional structure are preferably obtained by the pulp molding method. There are several different methods of pulp molding depending on the type of molded article to be produced. These include the thick wall method, which produces very thick molded articles with a film thickness of 5 mm to 10 mm and high load-bearing capacity; the transfer mold method, which produces molded articles with a film thickness of 3 mm to 5 mm and a smooth surface; the thermoformed mold method, which produces complex shapes with a film thickness of 1 mm to 3 mm; the PIM (Pulp injection mold) method, which produces more complex shapes such as bosses and ribs, like ordinary plastic molded articles; and the PF (Pulp forming) method, which produces lightweight and soft molded articles by foaming in the mold. Any method that does not belong to these classifications may be used as long as it is possible to create a three-dimensional shape. Various additives may be added to the liquid medium during molding.

[0100] <Use of composite molded products> The composite molded body described above can be used as a structure for a cell or as a separator in an assembly.

[0101] In this disclosure, "cell" refers to a single cell, which is the smallest 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, etc., are housed in an outer casing.

[0102] Examples of cells, though not limited to them, include lithium-ion batteries (LIBs), lithium-ion secondary batteries, nickel-metal hydride batteries, lithium-sulfur batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, sodium-sulfur batteries, lead-acid batteries, air batteries, all-solid-state batteries, and all-resin batteries. Among these, LIBs or lithium-ion secondary batteries are preferred from the viewpoint of the effects and benefits of the present invention.

[0103] In this disclosure, "assembly" refers to a collection of multiple cells, and "cell unit" refers to a battery pack including the assembly, which may also be called an energy storage module when housed in a casing, a cell stack when multiple cells are stacked, or a battery pack when multiple energy storage modules are housed in a casing. In addition to cells, the assembly and cell unit may include, as necessary, components such as electrical connection cables and lead tabs that are electrically connected to the cells.

[0104] The structure may consist of or contain a composite molded body.

[0105] A structure consisting of, or including, the composite molded body described above, can be used as a separator between multiple cells in an assembly and / or as a separator between multiple electrode materials in a cell.

[0106] In one embodiment, a method is provided for using a structure consisting of the composite molded body described above, or a structure including the composite molded body, as an inter-cell separator for LiBs. [Examples]

[0107] The following describes specific examples illustrating the structure and effects of the present invention, but the present invention is not limited in any way by the following examples.

[0108] <Density of non-combustible insulating particles> When using commercially available non-combustible insulating particles, the particle density may be the value stated in the publicly available data sheet. If the particle density is given as a range, the following formula applies: Particle density = (Particle density lower limit + Particle density upper limit) / 2 The value calculated by this method may be used as the particle density. However, if the upper / lower particle density limit listed in the datasheet is > 10, if multiple different non-combustible insulating particles are used in combination, or if the particle density published in the datasheet is unavailable, the value measured using a known instrument such as a helium pycnometer should be used.

[0109] <Average particle size of non-combustible insulating particles> When using commercially available non-combustible insulating particles, the average particle size may be the value stated in the published datasheet. If the average particle size is not specified, or if the particle size is specified as a specific range, the following formula may be used: Average particle size = (lower limit of particle size + upper limit of particle size) / 2 The value calculated by this method may be used as the average particle diameter. However, if the upper / lower particle diameter limit listed in the datasheet is > 5, if multiple different non-combustible insulating particles are used in combination, or if the average particle diameter published in the datasheet cannot be obtained or calculated, the value of the average particle diameter measured using a known instrument such as a sieve shaker (e.g., Retsch AS 200 basic) should be used.

[0110] <Average thickness of composite molded body> The average thickness of the composite molded body was measured according to the following procedure. (1) Sections measuring 5 cm x 5 cm were obtained from five different locations on the composite molded body. However, if the dimensions of the composite molded body are 5 cm x 5 cm or less, five sections were obtained from multiple composite molded bodies. (2) The thickness of each section was measured using an ABS Digimatic Indicator ID-CX (manufactured by Mitoyo Co., Ltd.). A 15 mm flat measuring probe was used for this measurement. (3) The average value of the five points obtained in procedure (2) was taken as the average thickness of the composite molded body.

[0111] 〈Volume of non-combustible heat-insulating particles〉 The volume of the non-combustible heat-insulating particles is determined as follows. Volume of non-combustible heat-insulating particles [cm 3 = Weight of non-combustible heat-insulating particles [g] / Density of non-combustible heat-insulating particles [g / cm 3

[0112] 〈Volume content ratio of non-combustible heat-insulating particles〉 The content ratio of the non-combustible heat-insulating particles in the composite molded body is determined as follows. Volume content ratio of non-combustible heat-insulating particles [vol%] = (Volume of non-combustible heat-insulating particles [cm 3 / Volume of the composite [cm 3 ) × 100

[0113] 〈Thermal conductivity of non-combustible heat-insulating particles〉 When using a commercially available product as the non-combustible heat-insulating particles, as the thermal conductivity, the representative value described in the published data sheet may be used. When multiple thermal conductivities are disclosed for each temperature, the thermal conductivity at room temperature or 20 - 25°C is used. When the thermal conductivity in the range of 20 - 25°C published in the data sheet etc. cannot be obtained, in the case of using a combination of multiple non-combustible heat-insulating particles, the measured value measured under the following conditions may be used. Figure 2 is a schematic front view (a) for explaining the measurement of the thermal conductivity of non-combustible heat-insulating particles, and a schematic side view (b) with two stainless steel plates fixed.

[0114] As illustrated in Figure 2(a), a 200 mm square was cut out from the center of a 7 mm thick, 300 mm square phenolic foam (thermal conductivity: 0.020 W / m·K). As illustrated in Figure 2(b), the upper and lower surfaces were fixed with stainless steel plates 0.5 mm thick and 250 mm square using Teflon (registered trademark) tape etc., and the cut-out part was filled with aerogel particles. The thermal conductivity at 23°C was measured in accordance with the flat plate heat flow method and in accordance with JIS A 1412 under the conditions of a low-temperature plate of 13°C and a high-temperature plate of �3°C.

[0115] ​ <Thermal conductivity of composite molded materials> Figure 3 is a schematic diagram illustrating the measurement of the thermal conductivity of a composite molded body. As illustrated in Figure 3, the composite molded body was placed on a 25 mm thick, 300 mm square sheet of phenolic foam (thermal conductivity: 0.020 W / m·K) for measurement. The thermal conductivity at 23°C was measured according to the flat plate heat flow method in accordance with JIS A 1412, under conditions of 13°C for the low-temperature plate and 33°C for the high-temperature plate. Series Model equation for the thermal conductivity of a two-component mixed system:

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[0116] <Composite molded material, heat-generating properties> A 100mm square sample was cut from the composite test specimen, and in accordance with ISO-5660, a cone calorimeter was used to measure the radiant heat at 50kW / m². 2 The maximum heat generation rate was measured when heated for 20 minutes.

[0117] <Flexibility and self-supporting properties of composite molded bodies> The flexibility and self-supporting properties of the composite molded body were evaluated based on the following criteria. [Flexibility and self-supporting properties of composite molded bodies] A: It has no obvious structural defects and will not break even if bent slightly. B: There are no obvious structural defects, but slight bending can cause partial cracks or breakage. C: There is a clear structural defect, or the structure collapses when slightly bent.

[0118] <Work safety of composite molded products> The work safety of the composite molded product was evaluated based on the following criteria. [Work safety of composite molded products] A: It is not irritating even when handled with bare hands. B: When handling it with bare hands, it can occasionally cause irritation. C: When handling it with bare hands, it frequently causes irritation.

[0119] <Fibrillated fiber A> Using linter pulp, a natural cellulose obtained from Nippon Paper Pulp Trading Co., Ltd., the linter pulp was immersed in water to a concentration of 1.5% by mass, then simply dispersed using a lab pulper (manufactured by Aikawa Iron Works), and finally transferred to a tank. The slurry was then refined while circulating by a single disc refiner (pre-stage) connected to the tank, which had a disc with a blade width of 2.5 mm and a groove width of 7.0 mm. At this time, operation was started with a blade distance of 1.0 mm, and the blade distance was gradually reduced until the final blade distance was 0.05 mm. After the blade distance reached 0.05 mm, operation was continued while monitoring the flow rate, and the operation was terminated when the entire slurry had passed through the disc section 10 times. Subsequently, the slurry was refined while circulating by a single disc refiner (post-stage) equipped with a disc with a blade width of 0.6 mm and a groove width of 1.0 mm. At this time, operation was started with a blade spacing of 1.0 mm, and the blade spacing was gradually reduced until the final blade spacing was 0.05 mm. After the blade spacing reached 0.05 mm, operation was continued while monitoring the flow rate, and the operation was terminated when the entire slurry had passed through the disc section 180 times. The obtained microfibrillated cellulose was designated as fibrillated fiber A. The moisture content of fibrillated fiber A was measured using an infrared moisture meter and found to be 1.0% by weight (wt%) of solid content.

[0120] <Fibrilized fiber B> Fibrillated polyacrylonitrile fibers, commonly known as acrylic pulp (manufactured by Nippon Exlan Industries Co., Ltd.: BiPUL, solid content 18% by mass), were used as fibrillated fiber B.

[0121] Example 1 As a heat-resistant organic staple fiber, oxidized PAN fiber (manufactured by SGL Carbon, trademark name: PANOX, grade: S2-1.7 / 1.39-A110, fiber length: 2.0 mm, linear density: 1.7 dtex, fiber density: 1.37 g / cm³) is used. 3 ), as fibrillated fibers, the aforementioned fibrillated fiber A, and as non-flammable insulating particles, silica aerogel powder (Cabot, grade name: IC3105, average particle size range: 0.1-0.5 mm, particle bulk density: 120-180 kg / m³) 3 Bulk density: 80-100 kg / m³ 3 , Specific surface area: 600-800m 2 The PAN-oxidized fibers (wt%) (thermal conductivity at room temperature: 0.018 W / m·K) were weighed out so that their dry weight fractions (wt%) were 63 wt%, 7 wt%, and 30 wt%, respectively, and added to a dispersion medium (water) so that the final solid concentration was 0.5 wt%. Furthermore, a papermaking dispersant (manufactured by Meisei Chemical Co., Ltd., grade name: Meikasurf BP-25) was added so that the solid content equivalent to 3.0 wt% of the weight of the PAN-oxidized fibers was added, and this was dispersed in the dispersion medium by stirring for 1 minute with a household mixer (manufactured by Vita-mix, model number: 4992831637653) (dispersion 1). If dispersion 1 could not be prepared with one mixer, multiple household mixers were operated simultaneously. Next, dispersion 1 was transferred to a 5L stainless steel beaker, and a papermaking viscous (manufactured by Meisei Chemical Co., Ltd., grade name: Pamol) was added to the dispersion medium to a final concentration of 10 ppm. The mixture was then stirred for 10 minutes at 500 rpm using a three-one motor (dispersion 2). Dispersion 2 obtained here was then fed into a rectangular sheet machine (manufactured by Kumagai Riki Kogyo Co., Ltd., product number: No. 2555, papermaking size: 250 mm) equipped with a metal mesh with a mesh size of Φ150, resulting in a surface density of 215 g / m² after removal of the dispersion medium. 2The mixture was introduced in this manner, and the dispersion medium was removed by suction filtration. The resulting molded body was sandwiched between absorbent sheets on both sides and compressed using a hydraulic press (manufactured by Kumagai Riki Kogyo Co., Ltd., product number: No. 2570-B, square plate dimensions: 420 mm square) at 0.1 MPa for 1 minute to further remove the dispersion medium. The compressed molded body was dried in a rotary dryer (manufactured by Kumagai Riki Kogyo Co., Ltd., product number: No. 2575-II) at 130°C until the moisture content of the molded body after drying was 5 wt% or less. The resulting molded body is designated as composite molded body A.

[0122] Figure 1 shows scanning electron microscope (SEM) images of composite molded body A at magnifications of (a) 100x and (b) 500x. From Figure 1, it was confirmed that the aerogel particles were dispersed within the framework of the oxidized PAN fibers.

[0123] Example 2 The dry weight ratio of heat-resistant organic short fibers, fibrillated fibers, and non-flammable insulating particles is 48 wt%, 12 wt%, and 40 wt%, and the surface density when dispersion 2 is fed into a rectangular sheet machine is 250 g / m². 2 A composite molded body was obtained in the same manner as in Example 1, except for the aforementioned difference. The obtained molded body is designated as composite molded body B.

[0124] Example 3 The surface density when dispersion 2 is introduced into the rectangular sheet machine is 430 g / m². 2 A composite molded body was obtained in the same manner as in Example 1, except for the aforementioned difference. The obtained molded body is designated as composite molded body C.

[0125] Example 4 When the dry weight ratio of heat-resistant organic short fibers, fibrillated fibers, and non-flammable insulating particles is 45 wt%, 5 wt%, and 50 wt%, and the dispersion 2 is fed into a rectangular sheet machine, the surface density is 600 g / m². 2 A composite molded body was obtained in the same manner as in Example 1, except for the aforementioned difference. The obtained molded body is designated as composite molded body D.

[0126] Example 5 The dry weight ratio of heat-resistant organic short fibers, fibrillated fibers, and non-flammable insulating particles is 73.8 wt%, 8.2 wt%, and 18 wt%, and the surface density when dispersion 2 is fed into a rectangular sheet machine is 360 g / m². 2 A composite molded body was obtained in the same manner as in Example 1, except for the aforementioned difference. The obtained molded body is designated as composite molded body E.

[0127] Example 6 A composite molded body was obtained in the same manner as in Example 1, except that fibrillated fiber B was used as the fibrillated fiber. The obtained molded body was designated as composite molded body F.

[0128] Comparative Example 1 A composite molded body was obtained in the same manner as in Example 1, except that PET short fibers (Teijin Corporation: TA04PN, fineness: 0.1T, average fiber diameter: 3.0 μm, cut length: 3 mm) were used instead of fibrillated fibers. The obtained molded body was designated as composite molded body I. Composite molded body I easily disintegrated when attempted to be lifted, making it impossible to measure various physical properties.

[0129] Comparative Example 2 As heat-resistant organic short fibers, PET fibers and fibrillated fibers, the aforementioned fibrillated fiber A, were measured out so that their dry weight fractions were 90 wt% and 10 wt%, respectively, and added to a dispersion medium (water) so that the final solid concentration was 0.5 wt%. Furthermore, a papermaking dispersant (manufactured by Meisei Chemical Co., Ltd., grade name: Meikasurf BP-25) was added so that the solid content equivalent to 3.0 wt% of the weight of the PET fibers was added, and this was dispersed in the dispersion medium by stirring for 1 minute using a household mixer (manufactured by Vita-mix, model number: 4992831637653) (dispersion 3). The obtained dispersion 3 was filtered and dried in the same procedure as in Example 1, and dried so that the moisture content of the molded body after drying was 5 wt% or less. The obtained molded body was designated as composite molded body J.

[0130] Comparative Example 3 A composite molded body K was prepared in the same manner as in Example 3, except that ceramic fibers were used as the heat-resistant short fibers.

[0131] Table 1 shows the evaluation results for Examples 1-6 and Comparative Examples 1-3.

[0132] [Table 1-1]

[0133] [Table 1-2] [Explanation of Symbols]

[0134] 1. Heat-resistant organic staple fibers 2. Fibrillated fibers 3. Non-combustible insulating particles

Claims

1. The following ingredients: (1) Heat-resistant organic staple fibers; (2) Fibrillated fibers; and (3) Non-combustible adiabatic particles A composite molded article containing the following:

2. The composite molded article according to claim 1, wherein the heat-resistant organic short fiber comprises oxidized polyacrylonitrile (PAN) fiber.

3. The composite molded article according to claim 1, comprising 10% or more by dry weight of oxidized polyacrylonitrile (PAN) fibers as the heat-resistant organic short fibers.

4. The composite molded article according to any one of claims 1 to 3, wherein the fibrillated fiber includes at least one selected from the group consisting of acrylic pulp, cellulose nanofibers, microfibrillated cellulose, chitin nanofibers, chitosan nanofibers, and aramid pulp.

5. The composite molded article according to any one of claims 1 to 3, wherein the fibrillated fiber comprises at least one selected from the group consisting of acrylic pulp, cellulose nanofibers, and microfibrillated cellulose.

6. The composite molded article according to any one of claims 1 to 3, wherein the non-flammable heat insulating particles include aerogel particles having an average particle diameter of 10 μm to 500 μm.

7. The composite molded article according to any one of claims 1 to 3, wherein the content of the non-combustible heat insulating particles is 10% by dry weight to 60% by dry weight.

8. The composite molded article according to any one of claims 1 to 3, wherein the content of the non-combustible heat insulating particles is 10% by volume to 60% by volume.

9. The composite molded article according to any one of claims 1 to 3, wherein the thermal conductivity of the composite molded article is 0.035 W / m·K or less.

10. The composite molded article according to any one of claims 1 to 3, wherein the average thickness of the composite molded article is 0.5 mm to 5.0 mm.

11. The composite molded article according to any one of claims 1 to 3, wherein the composite molded article is a paper-formed sheet.

12. The following steps: (i) A step of dispersing heat-resistant organic short fibers, fibrillated fibers, and non-flammable insulating particles in a solvent to obtain a dispersion, (ii) The step of removing the solvent from the dispersion by filtration and forming it into a flat film or a three-dimensional shape. A method for manufacturing a composite molded article, including [the specified element].

13. A method for producing a composite molded article according to claim 12, comprising the step of heating or drying a flat film-like or three-dimensional molded article at a temperature of 100°C or higher and less than 150°C.

14. A method for producing a composite molded article according to claim 12 or 13, wherein a flat film-like or three-dimensional molded article is obtained by wet papermaking.

15. A method for using a structure including a composite molded body according to any one of claims 1 to 3 as an inter-cell separator for a lithium-ion battery (LiB).

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