JP6639203B2 - Sheet containing cellulose fiber layer - Google Patents

Description

  The present invention relates to a sheet having a network structure made of cellulose fiber, a core material for a fiber-reinforced plastic film using the same, a core material for a vehicle, a core material for a printed wiring board for an electronic material, a core material for an insulating film, and a core. It relates to a core material for materials.

In recent years, fiber reinforced plastics (FRP) have attracted attention in various industrial fields as lightweight and high-strength materials. Fiber-reinforced composite materials consisting of glass fibers, carbon fibers, aramid fibers, and other reinforced fibers, and matrix resins are lightweight compared to competing metals, but have excellent mechanical properties such as strength and elastic modulus. It is used in many fields such as spacecraft components, automobile components, marine components, civil engineering and construction materials, and sporting goods. Particularly in applications requiring high performance, carbon fibers excellent in specific strength and specific elastic modulus are often used as reinforcing fibers. As the matrix resin, a thermosetting resin such as an unsaturated polyester resin, a vinyl ester resin, an epoxy resin, a phenol resin, a cyanate ester resin, and a bismaleimide resin is often used. Epoxy resins are widely used. Recently, in order to manufacture relatively large fiber reinforced plastic moldings at low cost, vacuum impregnation molding (VaRTM: Vacuum assist Resin Transfer Molding), which forms fiber reinforced plastics under reduced pressure by vacuum suction, has been adopted. (See, for example, Patent Document 1 below). On the other hand, fiber reinforced plastics manufactured by combining fibers and matrix resins studied in the past, because the fibers used are thick, their internal structure is clearly divided into fiber parts and resin parts, and as fiber reinforced plastics The effect of improving the mechanical properties is insufficient.
Here, the generally used fiber for FRP has a fiber diameter on the order of microns, so that a problem does not easily occur in the resin impregnation property of a thick film. However, simply converting general fibers into nanofibers increases the number of entanglement points per unit volume and improves the mechanical properties as FRP. However, the resin impregnation (permeability) is sufficient especially for applications requiring a thick film. Was not.

JP-A-60-83826

In view of the state of the above-mentioned technology, the present inventors have studied a technology for further improving the mechanical properties, and as a result, have increased the surface area by using nanofiberized fibers, and also have a thickness at the micron level. We paid attention to the fact that a hydrogen bonding network can be formed by controlling this, and a cellulose nanofiber sheet with extremely high thermal stability can be produced.
The problem to be solved by the present invention is to provide a sheet that is excellent in resin impregnation even though it is a thick film and that can improve sheet strength (elastic modulus) when combined.

[1] A sheet composed of a single layer containing at least one cellulose fiber layer containing 50% by weight or more of regenerated cellulose fibers or a plurality of layers of three or less layers, and the following requirements:
(1) The fiber constituting the cellulose fiber layer has a fiber diameter equivalent to a specific surface area of 0.20 μm or more and 2.0 μm or less;
(2) the thickness of the cellulose fiber layer is 20 μm or more;
( 3 ) air permeability resistance of the sheet is 1 s / 100 ml or more and 400,000 s / 100 ml or less; and ( 4 ) a film thickness of the sheet is more than 22 μm;
A sheet characterized by satisfying the following.
[2] The sheet according to [1], wherein the cellulose fiber layer contains 70% by weight or more of regenerated cellulose fibers.
[3] The sheet according to [1] or [2], wherein the air resistance is 5 s / 100 ml or more and 20,000 s / 100 ml or less.
[4] The regenerated cellulose fiber has a specific surface area equivalent fiber diameter of 0.20 μm or more and 2.0 μm or less, and the cellulose fiber layer contains fibers having a fiber diameter of 3 μm or more and 15 μm or less, more than 0% by weight and 30% by weight. The sheet according to any one of [1] to [3], which is included below.
[5] The sheet according to any one of [1] to [4], wherein the thickness of the sheet is more than 100 µm.
[6] The sheet according to any one of [1] to [5], wherein the fiber constituting the cellulose fiber layer has a fiber diameter equivalent to a specific surface area of 0.20 μm or more and 0.45 μm or less.
[7] The sheet according to any one of [1] to [6], wherein the basis weight of the cellulose fiber layer is 2 g / m ² or more.
[8] The sheet according to any of [1] to [7], wherein the cellulose fiber layer contains less than 50% by weight of natural cellulose fibers.
[9] The sheet according to [8], wherein the cellulose fiber layer contains less than 30% by weight of natural cellulose fibers.
[10] The sheet according to any of [1] to [7], wherein the cellulose fiber layer contains less than 50% by weight of a fiber made of an organic polymer other than cellulose.
[11] The sheet according to [10], wherein the cellulose fiber layer contains less than 30% by weight of a fiber made of an organic polymer other than cellulose.
[12] The sheet according to [11], wherein the fiber made of an organic polymer other than cellulose is aramid fiber and / or polyacrylonitrile fiber.
[13] The sheet according to any one of [1] to [12], wherein the cellulose fiber layer contains a reactive crosslinking agent in an amount of 10% by weight or less.
[14] one layer of the multilayer structure of more than the three layers having a basis weight including the base layer is a nonwoven fabric or paper is 5 g / ^{m 2} or more 200 g / ^{m 2} or less, any of [1] to [13] Crab sheet.
[15] and further with a multi-layer structure of more than the three-layer, sheet according to basis weight comprises a substrate layer is a nonwoven fabric or paper is 10 g / ^{m 2} or more 100 g / ^{m 2} or less, wherein [14].
[16] The method for producing a sheet according to any one of [1] to [15], including a water-based papermaking step.
[17] The method for producing a sheet according to any one of [1] to [15], including a coating step.
[18] The sheet according to any one of [1] to [15], used for sound insulation.
[19] (A) A composite film in which the sheet according to any of [1] to [15] is impregnated with (B) a resin.
[20] The composite film according to [19], wherein the resin (B) is one or more resins selected from the group consisting of a thermosetting resin, a photocuring resin, and a thermoplastic resin.
[21] The composite film according to [19] or [20], wherein the resin (B) is one or more of an epoxy resin, an acrylic resin, and a general-purpose plastic.
[22] The composite film according to any one of [19] to [21], wherein the resin (B) contains less than 50% by mass of inorganic fine particles.
[23] The composite film according to [22], wherein the inorganic fine particles are at least one selected from the group consisting of SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgO, ZnO, and BaTiO _3. .
[24] A composite prepreg film comprising (A) the sheet according to any of the above [1] to [15], and (B) a thermosetting resin and / or a photocurable resin.
[25] The composite prepreg film according to [24], wherein the resin (B) is an epoxy resin, an acrylic resin, and / or a polyimide resin.
[26] The composite prepreg film according to [24] or [25], wherein the resin (B) contains less than 50% by mass of inorganic fine particles.
[27] The composite prepreg according to [26], wherein the inorganic fine particles are at least one selected from the group consisting of SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , MgO, ZnO, and BaTiO _3. the film.
[28] A core material for a fiber-reinforced plastic film comprising the sheet according to any one of [1] to [15].
[29] The core material for a fiber-reinforced plastic film according to the above [28], for a vehicle-mounted material.
[30] The core material for a fiber-reinforced plastic film according to the above [28], for an electronic material.
[31] A prepreg for a fiber-reinforced plastic film, comprising the sheet according to any one of [1] to [15].
[32] A fiber-reinforced plastic film comprising the sheet according to any one of [1] to [15].
[33] The fiber-reinforced plastic film according to the above [32] for a vehicle-mounted material.

  The sheet of the present invention is excellent in resin impregnating property because it has a limited air permeability resistance range, that is, a pore diameter, although it is a thick film as a sheet. Therefore, for example, when used as a core material for a fiber reinforced plastic, thermal stability (reduction of linear thermal expansion coefficient and elasticity retention at high temperature) can be imparted when combined with a resin. Further, when used as a core material for in-vehicle materials, it is possible to secure mechanical properties when combined, while being lightweight as in-vehicle materials.

Hereinafter, embodiments of the present invention will be described in detail.
In the present embodiment, by using regenerated cellulose as a raw material, cellulose nanofibers having a fiber diameter in a predetermined range can be provided by miniaturization. The sheet produced in this way is thick as a sheet and has a limited air permeability resistance range, that is, a pore diameter, and thus has excellent resin impregnation properties. Therefore, for example, when used as a core material for a fiber-reinforced plastic, thermal stability (reduction in linear thermal expansion coefficient and retention of elastic modulus) can be imparted when combined with a resin. Further, when used as a core material for in-vehicle materials, sheet strength can be ensured while being thin as in-vehicle materials.
The regenerated cellulose fibers contained in the sheet of the present invention have a certain range of fiber diameters and therefore maintain a constant pore size, and also have a large number of entanglement points between the fibers, so that even when a thick film is formed, the strength is increased. While maintaining, it has the characteristics of being excellent in resin impregnating property and exhibiting flatness even when many layers are laminated due to small fiber diameter.

The sheet of the present embodiment is a sheet composed of a single layer containing at least one cellulose fiber layer containing 50% by weight or more of regenerated cellulose fibers or three or less layers.
(1) The fiber diameter corresponding to the specific surface area of the fibers constituting the cellulose fiber layer is 0.20 μm or more and 2.0 μm or less;
(2) air permeability is 1 s / 100 ml or more and 400,000 s / 100 ml or less; and (3) film thickness is more than 22 μm;
It is a sheet that satisfies. Such a sheet can be suitably used as a core material for a fiber-reinforced plastic film.
Hereinafter, the reason will be described.

  For example, in the field of fiber-reinforced plastic films, particularly in the field of in-vehicle and aircraft materials, there is a great need for a substrate to be lightweight and have a high elastic modulus. It can be a core material for a fiber reinforced plastic film, which is a material required in the field of use, is lightweight, has excellent suitability in processing steps such as resin impregnation, and has high thermal stability.

Hereinafter, the sheet of the present embodiment will be described in detail.
First, the cellulose fibers constituting the sheet of the embodiment will be described.
In the present embodiment, the regenerated cellulose is a substance obtained by regenerating natural cellulose by dissolving or crystal swelling (mercerizing) and regenerating it. The lattice spacings of the regenerated cellulose are 0.73 nm, 0.44 nm, and 0.4 nm by particle beam diffraction. Β-1,4-linked glucan (glucose polymer) having a molecular arrangement that gives a crystal diffraction pattern (cellulose type II crystal) having a diffraction angle corresponding to 40 nm as a vertex. In the X-ray diffraction pattern, the X-ray diffraction pattern in which the range of 2θ is 0 ° to 30 ° has one peak at 10 ° ≦ 2θ <19 ° and two peaks at 19 ° ≦ 2θ ≦ 30 °. Means, for example, regenerated cellulose fibers such as rayon, cupra, and tencel. Among these, it is preferable to use finely divided fibers made of cupra or tencel having high molecular orientation in the fiber axis direction from the viewpoint of ease of fineness.

  The maximum fiber thickness of the regenerated cellulose fiber is preferably 15 μm or less, more preferably 10 μm or less, further preferably 5 μm or less, and most preferably 3 μm or less. Here, that the maximum fiber thickness is 15 μm or less means that no fiber having a fiber diameter of more than 15 μm can be confirmed on an image by an electron microscope (SEM) of a cellulose nonwoven fabric measured under the following conditions. . A SEM image of the surface of the separator was collected at a magnification of 10,000 times, and the fiber diameter of any of the entangled fibers contained in the image was 15 μm or less. When a fiber having a fiber diameter of more than 15 μm cannot be confirmed for a total of 100 or more fibers, the maximum fiber diameter is defined to be 15 μm or less. However, if it is clearly confirmed that several fibers are multi-bunched in the image to have a fiber diameter of 15 μm or more, the fibers are not regarded as having a fiber diameter of 15 μm or more. When the regenerated cellulose filaments having a maximum fiber diameter of 3 μm or more and 15 μm or less are mixed with the regenerated cellulose fibers, or when the regenerated cellulose having a maximum fiber diameter of 3 μm or more and 15 μm or less remains after fineness, the resin of the thick film sheet is used. It is preferable because of its excellent impregnating property, and its content is preferably more than 0% by weight and 30% by weight or less.

As the sheet of the present embodiment, among the cellulose containing 50% by weight or more of the regenerated cellulose fibers, the fiber diameter equivalent to the specific surface area of the fiber layer is 2.0 μm or less, preferably 1.0 μm or less, more preferably 0.45 μm or less. And more preferably 0.40 μm or less. Here, the specific surface area equivalent fiber diameter will be described. First, the specific surface area was evaluated using the BET method by nitrogen adsorption, and the fibers constituting the separator were virtually in an ideal state in which no fusion occurred between fibers, and the cellulose density was lower than the specific surface area. According to a cylinder model assuming that the surface is composed of fibers that are cylinders having d (g / cm ³ ) and L / D (L: fiber length, D: fiber diameter (both in μm)) are infinite. The following formulas for specific surface area and fiber diameter:
Specific surface area = 4 / (dD) (m ² / g)
Was induced. The value converted into the fiber diameter D by substituting the specific surface area by the BET method as the specific surface area in the above equation and substituting d = 1.50 g / cm ³ as the cellulose density is defined as the specific surface area equivalent fiber diameter. Here, the specific surface area measurement by the BET method uses a specific surface area / pore distribution measuring device (manufactured by Beckman Coulter, Inc.) to measure the amount of nitrogen gas adsorbed at the boiling point of liquid nitrogen for about 0.2 g of a sample using the program. After measuring according to the formula, the specific surface area was calculated.

  The sheet of the present embodiment can suitably provide a sheet having a uniform thickness distribution by selecting the fiber diameter corresponding to the specific surface area of the cellulose fiber layer containing 50% by weight or more of the regenerated cellulose fibers in the above range. When the fiber diameter equivalent to the specific surface area of the cellulose fiber layer containing the regenerated cellulose fiber of 50% by weight or more exceeds 2.0 μm, the fiber diameter is too large, and the above-mentioned irregularities on the fiber sheet surface occur, and the distribution of the microporous structure is reduced. Since the holes become large, that is, holes having a large hole diameter are scattered, it becomes impossible to provide a thin and uniform sheet. Further, when the sheet of the present embodiment is used as a separator, if the fiber diameter corresponding to the specific surface area of the cellulose fiber layer exceeds 2.0 μm, it is not preferable from the viewpoint of short-circuit resistance.

  The cellulose fiber layer containing 50% by weight or more of regenerated cellulose fibers as the sheet of the present embodiment has a specific surface area equivalent fiber diameter of 0.20 μm or more, preferably 0.25 μm or more. When the fiber diameter corresponding to the specific surface area of the cellulose fiber layer containing 50% by weight or more of the regenerated cellulose fiber is less than 0.20 μm, the pore size of the fiber sheet becomes too small. Therefore, the resin is not impregnated when compounding the sheet and the resin for fiber reinforced plastic applications, and the fiber diameter is too small, which causes deterioration of the fiber reinforced plastic and increases the internal resistance over time and gas generation. It is not preferable because it may be connected. Further, at the time of producing a sheet in a paper making process and the like to be described later, fibers may come off and the yield may be reduced, which is not preferable.

  The sheet of the present embodiment contains regenerated cellulose fibers in an amount of 50% by weight or more. It is preferably at least 70% by weight, more preferably at least 80% by weight. By using a fiber containing 50% by weight or more of regenerated cellulose, when a sheet is formed by a papermaking method or a coating method using a cellulose nanofiber slurry in water, shrinkage of the fiber layer during drying is suppressed, and Can be maintained. Therefore, when the sheet and the resin are combined in a fiber-reinforced plastic application, the resin is easily impregnated and easily compounded, and the number of entangled points of the regenerated cellulose fiber is increased as compared with that of the ordinary cellulose fiber sheet. And thermal stability (combination of coefficient of linear thermal expansion, elasticity retention at high temperature) when combined with the above.

The sheet of the present embodiment is characterized in that the air resistance is in the range of 1 s / 100 cc to 400,000 s / 100 cc, preferably 100,000 s / 100 cc, more preferably 20,000 s / 100 cc. . Here, the air resistance means a value measured based on the Gurley tester method described in JIS P 8117. More preferably, the air resistance is in the range of 2 s / 100 cc to 10,000 s / 100 cc, further preferably, 5 s / 100 cc to 100 s / 100 cc, and most preferably, 8 s / 100 cc to 100 s / 100 cc. . In the case of a sheet having an air permeability lower than 1 s / 100 cc, it is difficult to produce a sheet uniformly without defects even though the sheet is composed of fine fibers. In addition, a fiber-reinforced plastic is not preferable because it causes a problem of strength and does not exhibit functions for various uses. On the other hand, when it exceeds 400,000 s / 100 cc, the porosity decreases or the pore diameter becomes too small. Therefore, when the sheet of the present invention is used as a fiber-reinforced plastic, the sheet is not impregnated with the resin, the composite is incomplete, and the thermal stability of the composite film, which should be originally exhibited (reduction of the coefficient of linear thermal expansion, Elastic retention at high temperatures).
Further, when the air resistance is 5,000 s / 100 cc or less, the resin is easily impregnated when the sheet and the resin are combined in a fiber-reinforced plastic application, so that it is preferable.

The sheet of the present embodiment can be obtained by processing cellulose fibers into a sheet as described above, but has a substantial film thickness of more than 22 μm. Here, the measurement of the film thickness is performed by using a surface contact type film thickness meter, for example, a film thickness meter (Model ID-C112XB) manufactured by Mitutoyo, etc., and cutting out 10.0 cm × 10.0 cm square pieces from various positions. The average value of the measured values at five points is defined as the film thickness T (μm). Further, from the thickness T (μm) of a 10.0 cm × 10.0 cm square piece cut out in the measurement of the film thickness and the weight W (g) thereof, the following formula:
W0 = 100 × W
Can be used to calculate the basis weight W0 (g / m ² ) of the film.

The sheet of the present embodiment is more preferably 100 μm or more and 10 mm or less. When the film thickness is in the above range, resin impregnation, strength (elastic modulus), and thermal stability can be imparted while maintaining flatness when a composite film is produced using the sheet. When the thickness is 22 μm or less, the strength (elastic modulus) and the thermal stability when impregnated with the resin may be poor.
In addition, the thickness of the fine cellulose layer itself is preferably 20 μm or more from the viewpoint of strength, and more preferably 50 μm or more.

The basis weight of the cellulose fiber layer used in the sheet of the present embodiment is 1 g / m ² or more, preferably 2 g / m ² or more and 1000 g / m ² or less, more preferably 3 g / m ² or more and 500 g / m ² or less. More preferably, it is 4 g / m ² or more and 100 g / m ² or less. If the basis weight is less than 1 g / m ² , it may be difficult to handle in the process of assembling various devices and may be inappropriate, which is not preferable from the viewpoint of long-term stability. The upper limit of the basis weight is not limited as long as there is no problem with the impregnating property of the resin, but is preferably 1000 g / m ² or less from the viewpoint of production.

  The cellulose fiber layer containing 50% by weight or more of regenerated cellulose fibers used in the sheet of the present embodiment may further contain less than 50% by weight of natural cellulose fibers in addition to the regenerated cellulose fibers. By using natural cellulose fibers, the production of fine cellulose fibers having a fiber diameter of less than 0.20 μm can be obtained relatively easily due to the fineness of the microfibrils which are the constituent units thereof. By mixing natural cellulose fibers having a large diameter ratio, the strength of the sheet can be increased. By containing less than 50% by weight of natural cellulose fibers, the strength of the cellulose fiber layer is increased, and a sheet having extremely good handleability and linear thermal expansion coefficient (CTE) when assembling a device is obtained. The content is more preferably less than 30% by weight.

As for the natural cellulose fiber diameter in the cellulose fiber layer used in the sheet of the present embodiment, the maximum fiber thickness is preferably 15 μm or less. When the maximum fiber diameter is 15 μm or less, it is preferable from the viewpoint of the surface flatness of the sheet.
Examples of natural cellulose fibers having a maximum fiber diameter of cellulose not exceeding 15 μm include wood pulp obtained from hardwood or coniferous wood, purified linter, or purified pulp from various plant species (bamboo, hemp fiber, bagasse, kenaf, linter, etc.). In addition to those obtained by the advanced treatment of natural cellulose fibers, natural cellulose fibers which are aggregates of never-dried and fine fibers such as bacterial cellulose (BC) produced by cellulose-producing bacteria (bacteria) are also included.

  Further, the cellulose fiber layer containing 50% by weight or more of the regenerated cellulose fiber used in the sheet of the present embodiment further contains less than 50% by weight of a fiber made of an organic polymer other than cellulose in addition to the regenerated cellulose fiber. And more preferably 30% by weight or less. As the organic polymer, any organic polymer capable of producing fibers can be used, for example, aromatic or aliphatic polyester, nylon, polyacrylonitrile, cellulose acetate, polyurethane, polyethylene, polypropylene, polyketone, and aromatic ketone. Examples include, but are not limited to, natural organic polymers other than cellulose, such as aromatic polyamides, polyimides, silk, and wool. Fibers made of the organic polymer are obtained by beating organic fibers, fibers highly fibrillated or refined by a fine treatment using a high-pressure homogenizer, fibers obtained by electrospinning using various polymers as raw materials, and various polymers as raw materials. Examples thereof include fibers obtained by a meltblown method, but are not limited thereto. Among them, particularly, the fine fibrous aramid obtained by miniaturizing the polyacrylonitrile nanofiber or the aramid fiber which is a wholly aromatic polyamide by a high-pressure homogenizer is preferably used in combination with the high heat resistance of the aramid fiber and the high chemical stability. be able to. The fiber diameter of these organic polymers is preferably such that the maximum fiber thickness is 15 μm or less.

Next, a method for producing a cellulose fiber will be described.
It is preferable that both the regenerated cellulose fiber and the natural cellulose fiber undergo a pretreatment step, a beating treatment step, and a refining step. In particular, when refining the regenerated cellulose fiber, the pretreatment step can be carried out in a water washing step using a surfactant in some cases to remove an oil agent. It is effective that the raw material pulp is easily made fine in the subsequent steps by autoclave treatment, enzymatic treatment, or the like under impregnation in water at a temperature of 150 ° C. During the pretreatment step, an autoclaving treatment may be performed by adding an inorganic acid (hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, etc.) or an organic acid (acetic acid, citric acid, etc.) at a concentration of 1% by weight or less. Some are valid. These pretreatments not only reduce the load of the micronization process, but also discharge the impurity components such as lignin and hemicellulose present on the surface and the gaps of the microfibrils constituting the cellulose fibers into the aqueous phase, and as a result, Since it also has the effect of increasing the α-cellulose purity of the converted fibers, it may be very effective in improving the heat resistance of the cellulose fiber nonwoven fabric.
After the beating treatment step, both regenerated cellulose fibers and natural cellulose fibers are produced with the following contents. In the beating treatment step, the raw material pulp is added in an amount of 0.5 to 4% by weight, preferably 0.8 to 3% by weight, more preferably 1.0 to 2.5% by weight. Disperse in water to a partial concentration and thoroughly promote fibrillation with a beater such as a beater or a disc refiner (double disc refiner). When a disc refiner is used, if the clearance between the discs is set as narrow as possible (for example, 0.1 mm or less) and the treatment is performed, extremely high-level beating (fibrillation) proceeds, so that a high-pressure homogenizer or the like is used. In some cases, the conditions for miniaturization can be relaxed and effective.

In the production of the cellulose fiber, it is preferable to perform a pulverization treatment using a high-pressure homogenizer, an ultra-high-pressure homogenizer, a grinder, or the like, following the beating step described above. At this time, the solid content concentration in the aqueous dispersion is 0.5% by weight or more and 4% by weight or less, preferably 0.8% by weight or more and 3% by weight or less, more preferably 1.0% by weight or less according to the above-described beating treatment. % By weight or more and 2.5% by weight or less. When the solid content concentration is in this range, clogging does not occur, and an efficient fine processing can be achieved.
Examples of the high-pressure homogenizer to be used include an NS-type high-pressure homogenizer of Niro Soavi (Italy), a Ranier type (R model) pressure-type homogenizer of SMT, and a high-pressure homogenizer of Sanwa Machine Co., Ltd. Any other device may be used as long as the device can be miniaturized by a mechanism substantially similar to these devices. The ultra-high pressure homogenizer means a high-pressure collision type miniaturization processing machine such as a microfluidizer of Mizuho Industry Co., Ltd., a Nanomizer of Yoshida Kikai Kogyo Co., Ltd., and an Ultimizer of Sugino Machine Co., Ltd. An apparatus other than these may be used as long as the apparatus performs the miniaturization with substantially the same mechanism. Examples of the grinder type refining device include a stone mill type grinding type represented by a pure fine mill of Kurita Machinery Co., Ltd. and a supermass colloider of Masuyuki Sangyo Co., Ltd. Any other device may be used as long as it performs the miniaturization by the mechanism described above.

The fiber diameter of the fine cellulose fiber is determined by the conditions of the fine treatment (selection of the apparatus, the operating pressure and the number of passes) using a high-pressure homogenizer or the conditions of the pretreatment before the fine treatment (for example, autoclave treatment, enzyme treatment, beating treatment). Etc.).
Furthermore, as natural cellulose fine fibers, cellulose-based fine fibers obtained by chemically treating the surface, and cellulose-based compounds in which a hydroxyl group at position 6 is oxidized by a TEMPO oxidation catalyst to become a carboxyl group (including an acid type and a salt type). Can also be used. In the former case, by performing various surface chemical treatments depending on the purpose, for example, some or most of the hydroxyl groups present on the surface of the fine cellulose fiber are esterified including acetate, nitrate, and sulfate. And etherified products including alkyl ethers represented by methyl ether, carboxy ethers represented by carboxymethyl ether, and cyanoethyl ether can be appropriately prepared and used. Further, in the latter, that is, in the preparation of fine cellulose fibers in which the hydroxyl group at position 6 is oxidized by the TEMPO oxidation catalyst, it is not always necessary to use a fine energy-reducing device such as a high-pressure homogenizer. A dispersion can be obtained. For example, as described in the literature (A. Isogai et al., Biomacromolecules, 7, 1687-1691 (2006)), 2,2,6,6-tetramethylpiperidinooxy is added to an aqueous dispersion of natural cellulose. A catalyst called TEMPO such as a radical coexists with an alkyl halide, an oxidizing agent such as hypochlorous acid is added thereto, and the reaction is allowed to proceed for a certain period of time. By performing the treatment, a dispersion of fine cellulose fibers can be obtained very easily.

  In the present embodiment, fine fibers of regenerated cellulose or natural cellulose based on the above-mentioned raw materials, fine fibers of natural cellulose having different degrees of fibrillation, fine fibers of natural cellulose whose surface is chemically treated, and fine fibers of organic polymer are used in the present embodiment. In some cases, it is also effective to form a cellulose fine fiber layer by mixing two or more of these components in a predetermined amount.

The cellulose fiber layer used in the sheet of the present embodiment is effective for reinforcing the strength even if it contains a reactive crosslinking agent at 10% by weight or less. The reactive cross-linking agent refers to a reactant derived from a polyfunctional isocyanate, and refers to a resin formed by an addition reaction between a polyfunctional isocyanate compound and an active hydrogen-containing compound. By containing the reactive cross-linking agent in an amount of 10% by weight or less, the strength of the cellulose fine fiber layer is increased, and the sheet becomes extremely good in handleability when assembling the device. It is more preferably at most 6% by weight.
Forming a reactive crosslinking agent in the cellulose fiber layer used in the sheet of the present embodiment, as the reactive crosslinking agent polyfunctional isocyanate compound, for example, aromatic polyfunctional isocyanate, araliphatic polyfunctional isocyanate, Alicyclic polyfunctional isocyanates, aliphatic polyfunctional isocyanates and the like can be mentioned. From the viewpoint of less yellowing, alicyclic polyfunctional isocyanates and aliphatic polyfunctional isocyanates are more preferred. Further, one or more polyfunctional isocyanate compounds may be contained.

Examples of the aromatic polyfunctional isocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and a mixture thereof (TDI), diphenylmethane-4,4′-diisocyanate (MDI), and naphthalene-1,5. Aromatic difunctional isocyanates such as diisocyanate, 3,3-dimethyl-4,4-biphenylene diisocyanate, crude TDI, polymethylene polyphenyl diisocyanate, crude MDI, phenylene diisocyanate and xylylene diisocyanate.
Examples of the alicyclic polyfunctional isocyanate include alicyclic polyfunctional isocyanates such as 1,3-cyclopentane diisocyanate, 1,3-cyclopentene diisocyanate, and cyclohexane diisocyanate.
Examples of the aliphatic polyfunctional isocyanate include aliphatic polyfunctional isocyanates such as trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate, pentamethylene diisocyanate, and hexamethylene diisocyanate.
Examples of the active hydrogen-containing compound include a hydroxyl group-containing compound containing a monohydric alcohol, a polyhydric alcohol and a phenol, an amino group-containing compound, a thiol group-containing compound, and a carboxyl group-containing compound. Further, water and carbon dioxide present in the air or in the reaction field are also included. One or more active hydrogen-containing compounds may be contained.

Examples of the monohydric alcohol include alkanols having 1 to 20 carbon atoms (such as methanol, ethanol, butanol, octanol, decanol, dodecyl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol), and alkanols having 2 to 20 carbon atoms (oleyl alcohol). And linolyl alcohol) and araliphatic alcohols having 7 to 20 carbon atoms (such as benzyl alcohol and naphthyl ethanol).
Examples of the polyhydric alcohol include dihydric alcohols having 2 to 20 carbon atoms [aliphatic diols (ethylene glycol, propylene glycol, 1,3- or 1,4-butanediol, 1,6-hexanediol, neopentyl glycol) And 1,10-decanediol, etc.), alicyclic diols (cyclohexanediol and cyclohexanedimethanol, etc.) and araliphatic diols {1,4-bis (hydroxyethyl) benzene, etc.} etc.), having 3 to 20 carbon atoms Trihydric alcohols [aliphatic triols (such as glycerin and trimethylolpropane)] and C4-20 hydric alcohols [aliphatic polyols (pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin and dipentaerythritol) Etc.) and sugars (sucrose, glue) Over scan, mannose, fructose, methyl glucoside and derivatives thereof)], and the like.

Examples of the phenols include monohydric phenols (phenol, 1-hydroxynaphthalene, anthrol, 1-hydroxypyrene, etc.), polyhydric phenols [phloroglucin, pyrogallol, catechol, hydroquinone, bisphenol A, bisphenol F, bisphenol S, 1,3,6,8-tetrahydroxynaphthalene, 1,4,5,8-tetrahydroxyanthracene, a condensate of phenol and formaldehyde (novolak), a polyphenol described in U.S. Pat. No. 3,265,641] and the like. Can be
Examples of the amino group-containing compound include monohydrocarbylamines having 1 to 20 carbon atoms [such as alkylamines (such as butylamine), benzylamine and aniline], and aliphatic polyamines having 2 to 20 carbon atoms (such as ethylenediamine, hexamethylenediamine, and the like). Alicyclic polyamines having 6 to 20 carbon atoms (such as diaminocyclohexane, dicyclohexylmethanediamine and isophoronediamine), aromatic polyamines having 2 to 20 carbon atoms (such as phenylenediamine, tolylenediamine and diphenylmethanediamine), carbon 2 to 20 heterocyclic polyamines (such as piperazine and N-aminoethylpiperazine), alkanolamines (such as monoethanolamine, diethanolamine and triethanolamine), dicarboxylic acid and excess polyamine Polyamide polyamine, polyether polyamine, hydrazine (such as hydrazine and monoalkyl hydrazine), dihydrazide (such as dihydrazide succinate and dihydrazide terephthalate), guanidine (such as butylguanidine and 1-cyanoguanidine) and dicyandiamide obtained by condensation with min. Is mentioned.

Examples of the thiol group-containing compound include monovalent thiol compounds having 1 to 20 carbon atoms (alkyl thiols such as ethyl thiol, phenyl thiol and benzyl thiol), and polyvalent thiol compounds (ethylene dithiol and 1,6-hexanedithiol) Etc.).
Examples of the carboxyl group-containing compound include monovalent carboxylic acid compounds (alkyl carboxylic acids such as acetic acid, aromatic carboxylic acids such as benzoic acid), polyvalent carboxylic acid compounds (alkyl dicarboxylic acids such as oxalic acid and malonic acid, and terephthalic acid). Aromatic dicarboxylic acids such as acids).

The cellulose fiber layer used in the sheet of the present embodiment has a basis weight of 2 g / m ² or more and 200 g / m ² or less, preferably 5 g / m ² or more and 100 g / m ² or less. It may include a substrate layer that is a nonwoven or paper. By including a substrate layer which is a nonwoven fabric or paper having a basis weight of 3 g / m ² or more and 200 g / m ² or less, even if the strength of the thin cellulose fiber layer itself is insufficient, the substrate layer compensates for the strength. For this reason, a sheet having extremely good handleability when producing members and components while maintaining the function as a sheet is obtained.

  Examples of the substrate layer used in the sheet of the present embodiment include polyamide fibers such as 6-nylon and 6,6-nylon, polyester fibers such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate, polyethylene fibers, and polypropylene. Nonwoven fabric or paper comprising at least one selected from the group consisting of fibers, natural cellulose fibers such as wood pulp and cotton linter, regenerated cellulose fibers such as viscose rayon and copper ammonia rayon, and purified cellulose fibers such as lyocell and tencel. From the viewpoint of impregnation of the electrolyte and the resin to be composited, cellulose, nylon and polypropylene are preferred. The base material layer can be suitably used as a melt-blow or electrospinning nonwoven fabric in the thickness range specified in the present invention.

  The sheet of the present embodiment may have an insulating porous film formed on one side or both sides. In particular, when the sheet is used as a separator for an electricity storage device, when the electricity storage device locally generates heat inside the battery due to an internal short circuit or the like, the separator around the heat generating portion shrinks and the internal short circuit further expands, Runaway heat generation may result in serious events such as ignition or rupture. By providing a laminated structure in which an insulating porous film is formed on one or both sides of the sheet, short-circuiting and expansion can be prevented, and a highly safe electricity storage device can be provided.

  Formed in the laminated film of the present embodiment, the insulating porous film on one or both surfaces is made of an inorganic filler and a thermosetting resin, without embedding the inorganic filler in the thermosetting resin, the gap between the inorganic filler. It is preferable to hold. Examples of the inorganic filler include, for example, inorganic oxides and hydroxides such as calcium carbonate, sodium carbonate, alumina, gibbsite, boehmite, magnesium oxide, magnesium hydroxide, silica, titanium oxide, barium titanate, and zirconium oxide, and aluminum nitride. And at least one selected from the group consisting of inorganic nitrides such as silicon nitride, calcium fluoride, barium fluoride, barium sulfate, silicon, aluminum compounds, zeolite, apatite, kaolin, mullite, spinel, olivine, mica, and montmorillonite. .

  Examples of the thermosetting resin used in the present embodiment include, for example, an epoxy resin, an acrylic resin, an oxetane resin, an unsaturated polyester resin, an alkyd resin, a novolak resin, a resole resin, a urea resin, and melamine. And the like. These can be used alone or in combination of two or more. These thermosetting resins are preferably water dispersions in terms of ease of handling and safety. The aqueous dispersion may contain a dispersant, an emulsifier, an organic solvent, and the like, if necessary. Examples of the epoxy resin include copolymers such as glycidyl acrylate, acrylic acid, methyl methacrylate, methacrylic acid, butyl methacrylate, and styrene. Examples of the acrylic resin include copolymers such as methyl methacrylate, butyl acrylate, methacrylic acid, hydroxyethyl methacrylate, and styrene.

Formed on the sheet of the present embodiment, the insulating porous film on one or both sides is made by contacting a mixed slurry of an inorganic filler and a thermosetting resin with a nonwoven fabric substrate, and drying, and is fixed to the cellulose fiber layer. . If necessary, a thickener, an antifoaming agent, and an organic solvent may be added to the mixed slurry.
The insulating porous film on one or both sides formed on the laminated film of the present embodiment preferably has a basis weight of 2 g / m ² or more and 10 g / m ² or less. When the basis weight is 2 g / m ² , pinholes may be generated. On the other hand, when the basis weight is greater than 10 g / m ² , the insulating layer becomes too thick to increase the internal resistance and the inorganic filler during bending. Powder falling and peeling may occur. The content of the inorganic filler in the laminated sheet is preferably 15.0 to 50.0% by weight. The solid content of the thermosetting resin in the separator is more preferably 1.0 to 15.0% by weight. If the content of the inorganic filler is less than 10.0% by weight and the solid content of the thermosetting resin is more than 20.0% by weight, pinholes may be generated. If the content of the inorganic filler is more than 70.0% by weight and the solid content of the thermosetting resin is less than 0.1% by weight, the inorganic filler may fall off or peel off.

  Further, in the sheet of the present embodiment, the chlorine ion content concentration, which is one measure of the amount of contained metal ions, is preferably 40 ppm or less depending on the use. When the chloride ion content is 40 ppm or less, metal ions such as Na and Ca are also contained at a relatively low concentration. As a result, for example, the heat resistance of the separator and the electric power of the electricity storage device incorporating the separator are reduced. This is because the inhibition of the characteristics can be suppressed. More preferably, the heat resistance is more preferably at most 30 ppm, most preferably at most 25 ppm. The evaluation of the chloride ion concentration can be performed by an ion chromatography method.

The main method for producing the sheet of the present embodiment is to form a dispersion of a highly regenerated cellulose fiber in a dispersion medium such as water by a papermaking method or a coating method. It is preferable to form a film by a papermaking method from the viewpoint of the efficiency of the method. Conventionally, in order to produce a sheet having a high porosity from cellulose fibers as in the present invention, fusion between fibers during drying, water in a wet paper formed by papermaking to suppress agglomeration. It was necessary to dry after replacing with an organic solvent, or to use a dispersion containing an organic solvent as a coating liquid for coating (for example, see Japanese Patent No. 4753874). However, in the present embodiment, by including a predetermined amount of regenerated cellulose fiber having a specific surface area equivalent diameter of 0.20 μm or more and 2.0 μm or less, an empty space required as a sheet by a papermaking method or a coating method without using an organic solvent. It has been found that the pores can be retained during drying. Here, the regenerated cellulose fiber having a specific surface area equivalent diameter of 0.20 μm or more and 2.0 μm or less is a single-layer papermaking (basis weight: 10 g / m ² ) from an aqueous dispersion containing only the relevant regenerated cellulose fiber. It means regenerated cellulose fibers having a specific surface area equivalent fiber diameter of 0.20 μm or more and 2.0 μm or less calculated from the specific surface area measured by the BET method of the single-layer sheet obtained at the time of film formation by the BET method. The fiber diameter corresponding to the specific surface area is preferably 0.25 μm or more. The fiber diameter corresponding to the specific surface area is preferably 1.0 μm or less, more preferably 0.45 μm or less, and most preferably 0.40 μm or less. When the specific surface area equivalent fiber diameter is smaller than 0.20 μm, it becomes difficult to maintain pores suitable for the sheet of the present invention from drying from an aqueous wet paper, and the specific surface area equivalent fiber diameter is less than 2.0 μm. When the thickness is too large, the problem that the thinning and uniformity cannot be achieved at the same time tends to occur.

When manufacturing the sheet of the present embodiment, a dispersion method for highly dispersing the cellulose fibers as an aqueous dispersion for papermaking or coating is also important, and the selection thereof is uniform in the thickness of the sheet described below. Has a significant effect on sex.
The dispersion containing the regenerated cellulose fibers obtained by the fibrillation treatment or the micronization treatment by the above-described production method is used as it is or diluted with water, and dispersed by an appropriate dispersion treatment to prepare the separator of the present embodiment. Can be used as a dispersion for papermaking or application. Components other than the regenerated cellulose fiber, for example, a fiber made of an organic polymer other than cellulose or natural cellulose fiber, or a reactive crosslinking agent may be mixed at any timing of each step of the dispersion production described above, for papermaking or It may be desirable to add it during the preparation of the dispersion for application. After mixing the components, the components are dispersed by an appropriate dispersion treatment to obtain a dispersion for papermaking or coating. In particular, regarding the timing of mixing fibers other than the regenerated cellulose fibers, the regenerated cellulose raw material (cut yarn) may be mixed and beaten in the beating step from the pulp or cut yarn stage, or the beaten-treated raw material may be mixed with a high-pressure homogenizer or the like. May be mixed in the step of performing the miniaturization treatment. The dilution treatment after dilution of the papermaking or coating dispersion or after mixing the raw materials may be performed by any dispersion method, but is appropriately selected according to the content of the mixed raw material components. For example, a disperser-type stirrer, various homomixers, various line mixers, and the like can be used, but are not limited thereto.

Hereinafter, a method of forming a film by a papermaking method will be mainly described.
The papermaking method can be carried out by using all industrially available continuous papermachines as well as batch-type papermachines. In particular, the composite sheet material of the present embodiment can be suitably manufactured by using an inclined wire type paper machine, a fourdrinier type paper machine, or a round net type paper machine. In order to improve the film quality uniformity, multi-stage paper making using one or two or more machines (for example, an inclined wire type paper machine is used for the underlayer papermaking and a round mesh type papermaking machine is used for the upper layer papermaking). Is effective in some cases. The papermaking multistage, for example, by performing carried out papermaking with a basis weight of 5 g / m ² in the first stage, the thus obtained wet the second stage of the paper of 5 g / m ² on paper, total 10 g / m ² This is a technique for obtaining the composite sheet material of the present invention having the following basis weight. In the case of multi-stage papermaking, when forming the upper layer and the lower layer from the same dispersion, a single-layer composite sheet material of the present invention is used. However, in the first step, the lower layer is finely divided using fibrillated fibers. A layer of a wet paper web is formed, and papermaking is performed with the above-described dispersion in the second stage, and the wet paper web, which is the lower layer, can function as a filter described later.

Since the sheet of this embodiment uses fine fibers, it is preferable to use a filter cloth or a plastic wire having a fine structure in which the fine fibers do not come off during paper making when forming a film by a paper making method. As a filter cloth or a plastic wire having such a fine structure, basically, the solid content in the dispersion for papermaking stops as wet paper, that is, 90% by weight of the solid content in the papermaking process. As described above, if a filter cloth or a plastic wire having a content of preferably 95% by weight or more, more preferably 99% by weight or more is selected, industrially suitable production becomes possible. The high yield also means that the penetration into the interior of the filter is low, and it is also preferable in that the releasability after papermaking is improved. In addition, it is desirable that the filter size be small, because the above-mentioned yield is improved. However, if the drainage is poor, the production speed of wet paper is unfavorably reduced. That is, the water permeation amount of wire mesh or cloth under 25 ° C. atmospheric pressure, is preferably 0.005ml / cm ² · s or more, more preferably 0.01ml / cm ² · s or more, productivity From the viewpoint of the above, suitable papermaking can be performed. Actually, it is preferable to select a filter cloth or a plastic wire having a high solid content yield and good drainage. Filter cloths and plastic wires satisfying the above conditions are limited. For example, TETEXMONODLW07-8435-SK010 (manufactured by PET) manufactured by SEFAR (Switzerland), NT20 (PET / nylon blend) manufactured by Shikishima Canvas as filter cloth, Examples include, but are not limited to, plastic wires LTT-9FE manufactured by Nippon Filcon, and multilayer wires described in JP-A-2011-42903.

  A papermaking dispersion prepared with a cellulose fiber concentration of 0.01% by weight or more and 0.5% by weight or less, more preferably 0.05% by weight or more and 0.3% by weight or less, on a filter cloth satisfying the above conditions. Then, the paper is deposited on the filter cloth by the operation of suction or the like to produce a wet paper having a solid content of 4% by weight or more of the cellulose fibers. The solid content at this time is preferably as high as possible, preferably 8% by weight or more, and more preferably 12% by weight or more. In general, by further pressing the wet paper, the dispersion medium in the papermaking dispersion can be removed with high efficiency, and the solid content in the obtained wet film can be increased. It is possible to obtain a wet paper having high strength. However, when a sheet having a relatively thick film is obtained, it is preferable not to perform the press treatment because a wet film having a large thickness, a low defect, a large hole diameter, and a high strength can be obtained. Further, a sheet having high flatness can be obtained without performing pressing, which is preferable from the viewpoint of productivity. Thereafter, a drying process is performed by a drying facility such as a drum dryer, and the sheet is wound up. In the drying step, the separator of the present invention can be obtained by drying the wet paper. Drying is usually performed under atmospheric pressure in a drum dryer or a pin tenter-type hot air drying chamber. In some cases, drying under pressure or under vacuum may be performed. At this time, it is more preferable to dry the wet paper with a drum dryer that can effectively dry at a fixed length for the purpose of securing uniformity of physical properties and suppressing shrinkage in the width direction. The drying temperature may be appropriately selected in the range of 60C to 150C. In some cases, multi-stage drying, such as a rough drying process at a low temperature of about 60 to 80 ° C. to give the wet paper web autonomy, and a main drying step at 100 ° C. or higher, is effective in operation. is there.

In order to continuously form a film of the sheet of the present embodiment, it is often effective to continuously perform the above-described paper making process and the drying process, and in some cases, the smoothing process by the calendering process. By performing the smoothing treatment by the calendering device, the above-mentioned thinning becomes possible, and it is possible to provide the sheet of the present invention in a wide range of combinations of film thickness / air resistance / strength. As a calender, a super calender having a structure in which these are installed in a multistage manner may be used in addition to a normal calender with a single press roll. By selecting these devices and the material (material hardness) and the linear pressure of each side of the roll at the time of calendering according to the purpose, the sheet of the present invention having various physical property balances can be obtained.
Further, in the above-described film forming process by papermaking, the filter cloth or plastic wire for papermaking used is an endless specification, and all the steps are performed by one wire, or an endless filter or an endless Of the film is picked up and transferred to a felt cloth, or transferred and transferred, or all or some of the steps of continuous film formation are performed as a roll-to-roll step using a filter cloth. However, the manufacturing method of the separator of the present embodiment is not limited to this.

Next, the combination of (A) the sheet of the present embodiment with (B) resin will be described.
Since the cellulose fiber layer containing the regenerated cellulose fibers in an amount of 50% by weight or more is designed to have a fiber diameter equivalent to a specific surface area of 0.20 μm or more and 2.0 μm or less, the number of entanglement points per unit volume, which is a characteristic of nanofibers, is large. Dry shrinkage due to cellulose hydroxyl groups during formation can be prevented, and porosity and pore size can be maintained. Since the pore diameter can be maintained, the resin can be easily impregnated into the cellulose fiber layer, and the cellulose fiber layer and the resin can be compounded.
Examples of the resin that can be impregnated into the regenerated cellulose fiber layer include a thermosetting resin and a photocurable resin, a resin obtained by thermosetting or photosetting these resins, and a thermoplastic resin.
Examples of the thermosetting resin that can be impregnated in the regenerated cellulose fiber layer include, for example, an epoxy resin, an acrylic resin, an oxetane resin, an unsaturated polyester resin, an alkyd resin, a novolak resin, a resol resin, a urea resin, Melamine resins and the like can be used, and these can be used alone or in combination of two or more.

  Thermosetting resin has excellent properties such as improvement of refractive index, improvement of curability, improvement of adhesion, improvement of flexibility of cured molded product, and improvement of handling property by reducing viscosity of thermosetting resin composition. For the purpose of providing a thermosetting resin composition having the following, it is preferable to add a thermosetting compound suitable for each purpose. These may be used alone or in a mixture of two or more. The addition amount of the thermosetting compound is preferably from 10 to 1,000 parts by weight, more preferably from 50 to 500 parts by weight, based on 100 parts by weight of the regenerated cellulose fiber layer. When the addition amount is 10 parts by mass or more, it is effective to exhibit thermal stability (reduction of linear thermal expansion coefficient, elasticity retention at high temperature), and when the addition amount is 1,000 parts by mass or less, thermosetting. It is possible to maintain high permeability and high heat resistance of the conductive resin assembly and the cured molded product.

  An epoxy compound that can be added as a thermosetting resin is, for example, an epoxy compound containing an aromatic group having thermal stability at high temperatures. An example is a glycidyl ether type epoxy resin having two or more functional groups. For example, bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetrabromobisphenol A, phenol novolak, cresol novolak, hydroquinone, resorcinol, 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylbiphenyl, Glycidyl ether type epoxy resin obtained by reaction of 1,6-dihydroxynaphthalene, 9,9-bis (4-hydroxyphenyl) fluorene, tris (p-hydroxyphenyl) methane, tetrakis (p-hydroxyphenyl) ethane and epichlorohydrin is used. No. Further, an epoxy resin having a dicyclopentadiene skeleton, an epoxy resin having a biphenylaralkyl skeleton, and triglycidyl isocyanurate can be used. In addition, an aliphatic epoxy resin and an alicyclic epoxy resin can be blended within a range that does not cause a significant decrease in Tg.

  In addition to the epoxy compound that can be added as a thermosetting resin, it is preferable to add a liquid aromatic diamine curing agent as a curing agent. Here, the term “liquid” refers to a liquid at 25 ° C. and 0.1 MPa. In addition, the aromatic diamine curing agent means a compound having two amine nitrogen atoms directly bonded to an aromatic ring in a molecule and having a plurality of active hydrogens. In addition, “active hydrogen” here refers to a hydrogen atom bonded to an amine nitrogen atom. It is necessary to be in a liquid state in order to ensure the impregnation property of the reinforcing fiber, and it is necessary to use an aromatic diamine curing agent in order to obtain a cured product having a high Tg. For example, 4,4'-methylenebis (2-ethylaniline), 4,4'-methylenebis (2-isopropylaniline), 4,4'-methylenebis (N-methylaniline), 4,4'-methylenebis (N- Ethylaniline), 4,4'-methylenebis (N-sec-butylaniline), N, N'-dimethyl-p-phenylenediamine, N, N'-diethyl-p-phenylenediamine, N, N'-di- sec-butyl-p-phenylenediamine, 2,4-diethyl-1,3-phenylenediamine, 4,6-diethyl-1,3-phenylenediamine, 2,4-diethyl-6-methyl-1,3-phenylene Liquid aromatic diamine curing agents such as diamine and 4,6-diethyl-2-methyl-1,3-phenylenediamine are exemplified. These liquid aromatic diamine curing agents may be used alone or in combination of two or more.

  Further, a latent curing agent may be added as the thermosetting resin of the present invention that can be added in addition to the epoxy compound. Latent curing agents are solid compounds that are insoluble in epoxy resins at room temperature, are solubilized by heating and function as curing accelerators, and are imidazole compounds that are solid at room temperature and solid dispersed amine adduct-based Examples of the curing accelerator include a reaction product of an amine compound and an epoxy compound (amine-epoxy adduct), and a reaction product of an amine compound and an isocyanate compound or a urea compound (urea-type adduct).

  Examples of the imidazole compound which is solid at ordinary temperature include 2-heptadecyl imidazole, 2-phenyl-4,5-dihydroxymethyl imidazole, 2-undecyl imidazole, 2-phenyl-4-methyl-5-hydroxymethyl imidazole, -Phenyl-4-benzyl-5-hydroxymethylimidazole, 2,4-diamino-6- (2-methylimidazolyl- (1))-ethyl-S-triazine, 2,4-diamino-6- (2'- Methylimidazolyl- (1) ′)-ethyl-S-triazine / isocyanuric acid adduct, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1 -Cyanoethyl-2-methylimidazole-trimellitate, 1 Examples include cyanoethyl-2-phenylimidazole-trimellitate, N- (2-methylimidazolyl-1-ethyl) -urea, N, N '-(2-methylimidazolyl- (1) -ethyl) -aziboyldiamide. However, the present invention is not limited to these.

  Examples of the epoxy compound used as one of the raw materials for producing the solid dispersion type amine adduct-based latent curing accelerator (amine-epoxy adduct) include polyphenols such as bisphenol A, bisphenol F, catechol and resorcinol, glycerin and Polyglycidyl ether obtained by reacting a polyhydric alcohol such as polyethylene glycol with epichlorohydrin; reacting a hydroxycarboxylic acid such as p-hydroxybenzoic acid or β-hydroxynaphthoic acid with epichlorohydrin Glycidyl ether ester obtained by the reaction; polyglycidyl ester obtained by reacting a polycarboxylic acid such as phthalic acid and terephthalic acid with epichlorohydrin; and epichlorohydrin such as 4,4'-diaminodiphenylmethane and m-aminophenol. A glycidylamine compound obtained by reacting with hydrin; furthermore, a multifunctional epoxy compound such as an epoxidized phenol novolak resin, an epoxidized cresol novolak resin, or an epoxidized polyolefin; Functional epoxy compound; and the like, but are not limited thereto.

  The amine compound used as another raw material for producing the solid dispersion type amine adduct-based latent curing accelerator has at least one active hydrogen in the molecule capable of undergoing an addition reaction with an epoxy group, and a primary amino group, What is necessary is just to have at least one functional group selected from the secondary amino group and the tertiary amino group in the molecule. Examples of such amine compounds are shown below, but are not limited thereto. That is, aliphatic amines such as, for example, diethylenetriamine, triethylenetetramine, n-propylamine, 2-hydroxyethylaminopropylamine, cyclohexylamine, 4,4'-diamino-dicyclohexylmethane; 4,4'-diaminodiphenylmethane And aromatic amine compounds such as 2-methylaniline; nitrogen-containing heterocycles such as 2-ethyl-4-methylimidazole, 2-ethyl-4-methylimidazoline, 2,4-dimethylimidazoline, piperidine and piperazine Compounds; and the like.

Further, a photo-acid generator may be added as a thermosetting resin of the present invention that can be added in addition to the epoxy compound. As the photoacid generator, those that generate a cationically polymerizable acid by irradiation with ultraviolet rays are used. Examples of such a photoacid generator include anions such as SbF ₆ ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , (C ₆ F ₅ ) ₄ ⁻ , and PF ₄ (CF ₂ CF ₃ ) ₂ ^−. Onium salts (a diazonium salt, a sulfonium salt, an iodonium salt, a selenium salt, a pyridinium salt, a ferrocenium salt, a phosphonium salt, etc.) comprising a component and a cation component are exemplified. These may be used alone or in combination of two or more. Specifically, an aromatic sulfonium salt, an aromatic iodonium salt, an aromatic phosphonium salt, an aromatic sulfoxonium salt, or the like can be used. Among them, from the viewpoint of photocurability and transparency, a photoacid generator containing hexafluorophosphate or hexafluoroantimonate as an anion component is preferable.
It is necessary to set the content of the photoacid generator in the range of 0.5 to 2.0 parts by weight based on 100 parts by weight of the total weight of the epoxy compound. More preferably, it is in the range of 0.5 to 1.5 parts by weight. If the content of the photoacid generator is too small, the curability may be deteriorated or the heat resistance may be reduced. If the content is too large, the curability is improved while the transparency is impaired.

  In addition, in addition to the above-described components, other additives can be appropriately added to the thermosetting resin of the present invention, which can be added in addition to the epoxy compound, if necessary. For example, a photosensitizer such as anthracene, an acid multiplying agent, and the like can be added as needed for the purpose of enhancing curability. In the case of using a cured product on a substrate such as glass, a coupling agent such as a silane-based or titanium-based coupling agent may be added in order to enhance the adhesiveness to the substrate. Further, an antioxidant, an antifoaming agent and the like can be appropriately compounded. These may be used alone or in combination of two or more. It is preferable to use these other additives in a range of 5% by weight or less based on the whole curable resin composition, from the viewpoint of not impairing the effects of the present invention.

Examples of the photocurable resin that can be impregnated into the regenerated cellulose fiber layer include compounds having one or more (meth) acryloyl groups in one molecule.
Photo-curable resins have the characteristics of improved refractive index, improved curability, improved adhesion, improved flexibility of cured molded products, and improved handling properties due to reduced viscosity of the photosensitive resin composition. It is preferable to add a compound having one or two or more (meth) acryloyl groups in one molecule suitable for each purpose in order to provide a photosensitive resin composition having the same. These may be used alone or in a mixture of two or more. The amount of the compound having one or two or more (meth) acryloyl groups in one molecule is preferably from 10 to 1,000 parts by weight, and more preferably from 50 to 500 parts by weight, per 100 parts by weight of the regenerated cellulose fiber layer. It is more preferred to be parts by mass. When the addition amount is 10 parts by mass or more, it is effective to exhibit thermal stability (reduction of linear thermal expansion coefficient, elasticity retention at high temperature), and when the addition amount is 1,000 parts by mass or less, photosensitive High permeability and high heat resistance of the resin assembly and the cured molded article can be maintained.

  The (meth) acrylate compound that can be added as a photocurable resin is, for example, a (meth) acrylate compound containing an aromatic group having thermal stability at high temperatures. Examples include phenoxyethyl acrylate, paraphenylphenoxyethyl acrylate (Aronix TO-1463, manufactured by Toagosei Co., Ltd.), paraphenylphenyl acrylate (Aronix TO-2344, manufactured by Toagosei Co., Ltd.), phenylglycidyl ether acrylate (hereinafter, "PGEA"). Benzyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenol (meth) acrylate modified with 3 to 15 mol of ethylene oxide, cresol (meth) modified with 1 to 15 mol of ethylene oxide Acrylate, nonylphenol (meth) acrylate modified with 1 to 20 mol of ethylene oxide, nonylphenol (meth) acrylate modified with 1 to 15 mol of propylene oxide ) Acrylate, bisphenol A di (meth) acrylate modified with 1 to 30 mol of ethylene oxide, bisphenol A di (meth) acrylate modified with 1 to 30 mol of propylene oxide, modified with 1 to 30 mol of ethylene oxide Preferred examples thereof include bisphenol F di (meth) acrylate, and bisphenol F di (meth) acrylate modified with 1 to 30 mol of propylene oxide. These may be used alone or in a mixture of two or more.

It is important that a photopolymerization initiator be added to the photocurable resin for the purpose of providing a photosensitive pattern.
Examples of the photopolymerization initiator (C) include the following photopolymerization initiators (1) to (10):
(1) Benzophenone derivatives: for example, benzophenone, methyl o-benzoylbenzoate, 4-benzoyl-4′-methyldiphenylketone, dibenzylketone, fluorenone,
(2) Acetophenone derivative: For example, 2,2'-diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one (IRGACURE651 manufactured by BASF) , 1-hydroxycyclohexylphenyl ketone (IRGACURE 184 manufactured by BASF), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (IRGACURE907 manufactured by BASF), 2-hydroxy-1 -{4- [4- (2-hydroxy-2-methylpropionyl) -benzyl] -phenyl} -2-methylpropan-1-one (IRGACURE127 manufactured by BASF), methyl phenylglyoxylate,
(3) Thioxanthone derivatives: for example, thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, diethylthioxanthone,
(4) benzyl derivatives: for example, benzyl, benzyl dimethyl ketal, benzyl-β-methoxyethyl acetal,
(5) Benzoin derivative: For example, benzoin, benzoin methyl ether, 2-hydroxy-2-methyl-1 phenylpropan-1-one (DAROCURE 1173, manufactured by BASF),
(6) Oxime compounds: For example, 1-phenyl-1,2-butanedione-2- (O-methoxycarbonyl) oxime, 1-phenyl-1,2-propanedione-2- (O-methoxycarbonyl) oxime, 1-phenyl-1,2-propanedione-2- (O-ethoxycarbonyl) oxime, 1-phenyl-1,2-propanedione-2- (O-benzoyl) oxime, 1,3-diphenylpropanetrione-2 -(O-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxypropanetrione-2- (O-benzoyl) oxime, 1,2-octanedione, 1- [4- (phenylthio) -2- (O-benzoyl) Oxime)] (IRGACURE OXE01 manufactured by BASF), ethanone, 1- [9-ethyl-6- (2-methylbenzo) Le) -9H- carbazol-3-yl] -, 1- (O- acetyloxime) (BASF Corp. IRGACURE OXE02),
(7) α-hydroxyketone compounds: for example, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl -1-propan-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) -benzyl] phenyl} -2-methylpropane,
(8) α-aminoalkylphenone-based compound: For example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (IRGACURE369 manufactured by BASF), 2-dimethylamino-2- ( 4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) butan-1-one (IRGACURE379 manufactured by BASF);
(9) Phosphine oxide compound: For example, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (IRGACURE819 manufactured by BASF), bis (2,6-dimethoxybenzoyl) -2,4,4- Trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (LUCIRIN TPO, manufactured by BASF),
(10) Titanocene compound: For example, bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium (manufactured by BASF) IRGACURE 784).
The photopolymerization initiators (1) to (10) may be used alone or in combination of two or more.

The content of the photopolymerization initiator is preferably 0.01% by mass or more, more preferably 0.1% by mass, from the viewpoint of obtaining sufficient sensitivity, based on the mass of all components other than the solvent in the photosensitive resin composition. %, On the other hand, from the viewpoint of sufficiently curing the bottom portion of the photosensitive resin layer, the amount is preferably 15% by mass or less, more preferably 10% by mass or less.
If desired, a sensitizer for improving photosensitivity can be added to the photocurable resin. Such sensitizers include, for example, Michler's ketone, 4,4'-bis (diethylamino) benzophenone, 2,5-bis (4'-diethylaminobenzylidene) cyclopentanone, 2,6-bis (4'-diethylamino) Benzylidene) cyclohexanone, 2,6-bis (4′-dimethylaminobenzylidene) -4-methylcyclohexanone, 2,6-bis (4′-diethylaminobenzylidene) -4-methylcyclohexanone, 4,4′-bis (dimethylamino) ) Chalcone, 4,4'-bis (diethylamino) chalcone, 2- (4'-dimethylaminocinnamylidene) indanone, 2- (4'-dimethylaminobenzylidene) indanone, 2- (p-4'-dimethylamino) Biphenyl) benzothiazole, 1,3-bis (4-dimethylaminobenzylide) Acetone, 1,3-bis (4-diethylaminobenzylidene) acetone, 3,3'-carbonyl-bis (7-diethylaminocoumarin), 3-acetyl-7-dimethylaminocoumarin, 3-ethoxycarbonyl-7-dimethyl Aminocoumarin, 3-benzyloxycarbonyl-7-dimethylaminocoumarin, 3-methoxycarbonyl-7-diethylaminocoumarin, 3-ethoxycarbonyl-7-diethylaminocoumarin, N-phenyl-N-ethylethanolamine, N-phenyldiethanolamine, Np-tolyldiethanolamine, N-phenylethanolamine, N, N-bis (2-hydroxyethyl) aniline, 4-morpholinobenzophenone, isoamyl 4-dimethylaminobenzoate, isoamino 4-diethylaminobenzoate , Benztriazole, 2-mercaptobenzimidazole, 1-phenyl-5-mercapto-1,2,3,4-tetrazole, 1-cyclohexyl-5-mercapto-1,2,3,4-tetrazole, 1- ( tert-butyl) -5-mercapto-1,2,3,4-tetrazole, 2-mercaptobenzothiazole, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) benzothiazole, -(P-dimethylaminostyryl) naphtho (1,2-p) thiazole, 2- (p-dimethylaminobenzoyl) styrene and the like. In use, they may be used alone or as a mixture of two or more.

If desired, a polymerization inhibitor can be added to the photosensitive resin composition for the purpose of improving the viscosity during storage and the stability of photosensitivity. Examples of such a polymerization inhibitor include hydroquinone, N-nitrosodiphenylamine, p-tert-butylcatechol, phenothiazine, N-phenylnaphthylamine, ethylenediaminetetraacetic acid, 1,2-cyclohexanediaminetetraacetic acid, glycol ether diaminetetraacetic acid. , 2,6-di-tert-butyl-p-methylphenol, 5-nitroso-8-hydroxyquinoline, 1-nitroso-2-naphthol, 2-nitroso-1-naphthol, 2-nitroso-5- (N- Ethyl-N-sulfopropylamino) phenol, N-nitroso-N-phenylhydroxyamine ammonium salt, N-nitroso-N-phenylhydroxylamine ammonium salt, N-nitroso-N- (1-naphthyl) hydroxylamine ammonium salt ,Screw Or the like can be used 4-hydroxy-3,5-di-tert- butyl) phenyl methane.
In addition to the above, the photosensitive resin composition, including an ultraviolet absorber and a coating smoothness imparting agent, etc., as long as it does not inhibit the various characteristics of the photosensitive resin composition, if necessary, various Additives can be appropriately compounded.

  As the resin that can be impregnated in the regenerated cellulose fiber layer, a thermosetting resin or a photocurable resin can be used, but the resin is impregnated in a short time by injection molding or the like on a sheet-like base material and is provided for molding of a mass-produced product or the like. It is preferable to use a thermoplastic resin from the viewpoint that the resin can be easily handled by various molding shapes. The thermoplastic resin used is not particularly limited. For example, polyolefins such as general-purpose plastics (polyethylene, polypropylene, etc.), ABS, polyamide, polyester, polyphenylene ether, polyacetal, polycarbonate, polyphenylene sulfide, polyimide, polyetherimide, Polyethersulfone, polyketone, polyetheretherketone, combinations thereof, and the like can be used.

  Further, inorganic fine particles may be added to the resin to be impregnated into the regenerated cellulose fiber layer, from the viewpoint of improving the thermal stability (linear thermal expansion coefficient and elasticity retention at high temperatures) of the resin. As the inorganic fine particles, for example, those having excellent heat resistance include alumina, magnesia, titania, zirconia, silica (quartz, fumed silica, precipitated silica, silicic anhydride, fused silica, crystalline silica, and ultrafine amorphous powder) Silica, etc.); those having excellent thermal conductivity include boron nitride, aluminum nitride, alumina oxide, titanium oxide, magnesium oxide, zinc oxide, silicon oxide, etc .; those having excellent conductivity include simple metals or alloys (for example, Metal filler and / or metal-coated filler using iron, copper, magnesium, aluminum, gold, silver, platinum, zinc, manganese, stainless steel, etc .; mica, clay, kaolin, talc as those having excellent barrier properties , Zeolite, wollastonite, smectite and other minerals, potassium titanate, magnesium sulfate , Sepiolite, zonolite, aluminum borate, calcium acid, titanium oxide, barium sulfate, zinc oxide, magnesium hydroxide; those having a high refractive index include barium titanate, zirconia, titanium oxide, etc .; Examples include titanium, cerium, zinc, copper, aluminum, tin, indium, phosphorus, carbon, sulfur, terium, nickel, iron, cobalt, silver, molybdenum, strontium, chromium, barium, lead, and other photocatalytic metals, Composites, their oxides and the like; metals having excellent abrasion resistance include metals such as silica, alumina, zirconia, and magnesium; and composites and oxides thereof; silver, copper, and the like having excellent conductivity Metals such as tin oxide, indium oxide, etc .; those having excellent insulating properties include silica, etc .; The excellent in line shielding, titanium oxide, zinc oxide and the like. These inorganic fine particles may be appropriately selected depending on the application, and may be used alone or in combination of two or more. In addition, the above-mentioned inorganic fine particles have various characteristics in addition to the specially-manufactured ones mentioned in the examples, and may be selected according to the intended use in a timely manner.

  For example, when silica is used as the inorganic fine particles, there is no particular limitation, and known silica fine particles such as powdered silica and colloidal silica can be used. Commercially available powdery silica fine particles include, for example, Aerosil 50 and 200 manufactured by Nippon Aerosil Co., Ltd., Sildex H31, H32, H51, H52, H121 and H122 manufactured by Asahi Glass Co., Ltd., and E220A manufactured by Nippon Silica Industry Co., Ltd. , E220, SYLYSIA470 manufactured by Fuji Silysia K.K., SG flake manufactured by Nippon Sheet Glass Co., Ltd., and the like. Examples of commercially available colloidal silica include methanol silica sol manufactured by Nissan Chemical Industries, Ltd., IPA-ST, PGM-ST, NBA-ST, XBA-ST, DMAC-ST, ST-UP, ST-OUP, ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, ST-OL and the like can be mentioned.

  Surface-modified silica fine particles may be used. For example, silica fine particles having a surface treated with a reactive silane coupling agent having a hydrophobic group or those modified with a compound having a (meth) acryloyl group may be used. can give. Commercially available powdered silica modified with a compound having a (meth) acryloyl group includes commercially available colloidal silica modified with a compound having a (meth) acryloyl group, such as Aerosil RM50, R7200, and R711 manufactured by Nippon Aerosil Co., Ltd. Is a colloidal silica surface-treated with a reactive silane coupling agent having a hydrophobic group such as MIBK-SD and MEK-SD manufactured by Nissan Chemical Industries, Ltd., and MIBK-ST manufactured by Nissan Chemical Industries, Ltd. MEK-ST and the like.

The shape of the silica fine particles is not particularly limited, and may be spherical, hollow, porous, rod-like, plate-like, fibrous, or irregular. For example, as commercially available hollow silica fine particles, Silex available from Nippon Steel Mining Co., Ltd. can be used.
The primary particle diameter of the inorganic fine particles is preferably in the range of 5 to 2,000 nm. When the thickness is 5 nm or more, the dispersion of the inorganic fine particles in the dispersion becomes good, and when the diameter is 2,000 nm or less, the strength of the cured product becomes good. More preferably, it is 10 nm to 1,000 nm. Here, the “particle size” is measured using a scanning electron microscope (TEM) or the like.
The inorganic fine particles are preferably blended at a ratio of 5 to 50% by weight based on the total solid content of the resin composite. For example, in the case of a heat-resistant material, the silica fine particles are preferably 5 to 50% by weight in order to achieve both a low coefficient of linear expansion and high strength of the cured product, and 20 to 50% by weight in order to further reduce the coefficient of linear expansion. More preferably, it is added in a proportion of 50% by weight, more preferably 30 to 50% by weight.

  When impregnating the regenerated cellulose fiber layer with the resin, the viscosity can be adjusted by adding a solvent as necessary. Suitable solvents include N, N-dimethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, tetrahydrofuran, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, pyridine, cyclohexane Pentanone, γ-butyrolactone, α-acetyl-γ-butyrolactone, tetramethylurea, 1,3-dimethyl-2-imidazolinone, N-cyclohexyl-2-pyrrolidone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, methyl ethyl ketone , Methyl isobutyl ketone, anisole, ethyl acetate, ethyl lactate, butyl lactate, etc., and these can be used alone or in combination of two or more. Among these, N-methyl-2-pyrrolidone, γ-butyrolactone, and propylene glycol monomethyl ether acetate are particularly preferred. These solvents can be appropriately added at the time of impregnation of the regenerated cellulose fiber layer with the resin according to the coating film thickness and the viscosity.

  The method for impregnating the regenerated cellulose fiber layer with the resin is not particularly limited, but after shaping and / or laminating a prepreg in which a sheet is impregnated with a thermosetting resin composition, and then shaping and / or laminating the sheet. Prepreg lamination molding method in which the resin is heated and cured while applying pressure to the material, resin transfer molding method in which the sheet is directly impregnated with the liquid thermosetting resin composition, and then cured, and the sheet is formed of the liquid thermosetting resin composition. After being continuously passed through a filled impregnation tank and impregnated with the thermosetting resin composition, while being continuously pulled out by a tensioning machine through a squeeze die and a heating mold, molding and curing are performed by a pultrusion method or the like. Can be.

Examples of the method of impregnating the resin include a wet method and a hot melt method (dry method).
The wet method is an epoxy resin composition or a photocurable resin composition in a solvent such as methyl ethyl ketone, after immersing the sheet in a solution in which a thermoplastic resin is dissolved, pull up the sheet, evaporate the solvent using an oven or the like, This is a method of impregnating a resin. The hot melt method is a method of directly impregnating a sheet with an epoxy resin composition, a photocurable resin composition, or a thermoplastic resin whose viscosity has been reduced by heating, and a film in which the epoxy resin composition is coated on release paper or the like. In this method, the film is stacked on both sides or one side of the reinforcing fiber, and the reinforcing fiber is impregnated with a resin by heating and pressing. At this time, it is preferable to perform a vacuum defoaming step to deaerate the air. Further, since there is no solvent remaining in the prepreg, it is preferable to use a hot melt method.

  The content of the cellulose fiber layer in the prepreg or its cured resin or thermoplastic resin is preferably 1 to 80% by weight, more preferably 5 to 50% by weight, and further preferably 10 to 30% by weight. . If the weight content of the cellulose fiber layer is less than 1% by weight, the ratio of the resin is too high, so that it is difficult to obtain the advantage of a composite material having excellent linear thermal expansion coefficient and elastic modulus when composited. Further, when the mass content of the reinforcing fibers exceeds 80% by weight, the impregnated amount of the resin is insufficient, so that the obtained composite material has many voids and the strength required as a film is low.

The sheet of the present embodiment can be suitably used as a core material for a fiber-reinforced plastic, more specifically, a core material or a core material for a vehicle-mounted or aircraft material. That is, especially when made of fiber reinforced plastic, it can meet the needs of high elasticity, high heat resistance and light weight in the field of in-vehicle and aircraft materials. For in-vehicle use, it has a high degree of freedom in moldability, so it is used for both interior and exterior, and is used for roofs, bumpers, doors, front-end modules, and the like. Furthermore, since the sheet has flatness and low defects, it is easy to design various applications.
Further, since the sheet alone or the core material has a high elastic modulus, it can be used as a material for absorbing and blocking sound and vibration, and because of its excellent thermal conductivity, it can be used as a heat dissipation sheet.
Since the sheet of this embodiment becomes high strength and lightweight by being compounded with a resin, it can be used as a substitute for a steel plate or a carbon fiber reinforced plastic. Examples thereof include industrial machine parts (eg, electromagnetic equipment housings, roll materials, transfer arms, medical equipment members, etc.), general machine parts, automobile / railway / vehicle parts (eg, outer plates, chassis, aerodynamics). Components, seats, etc.), marine components (eg, hulls, seats, etc.), aviation-related components (eg, fuselage, main wings, tail fins, rotor blades, fairings, cowls, doors, seats, interior materials, etc.), spacecraft, satellites Materials (motor case, main wing, structure, antenna, etc.), electronic and electric parts (for example, personal computer housing, mobile phone housing, OA equipment, AV equipment, telephone, facsimile, home appliances, toy supplies, etc.), construction and civil engineering Materials (for example, reinforcing bar replacement materials, truss structures, suspension bridge cables, etc.), daily necessities, sports and leisure goods (for example, golf club shafts, fishing rods, teni And like racket badminton), a wind power generation housing member or the like, also containers and packaging member, for example, can be a material for the high pressure container for filling and hydrogen gas as used in a fuel cell.
In addition to the above-mentioned uses, it can be applied as a material for various functional papers, absorbent materials, supports for medical materials, and the like.

Hereinafter, the present invention will be described specifically with reference to Examples, but the scope of the present invention is not limited to the following Examples.
[Preparation of sheet]
[Example 1]
Tencel cut yarn (3 mm length), which is a regenerated cellulose fiber obtained from Sojitz Corporation, is put into a washing net, a surfactant is added, and the washing is repeated with a washing machine to remove oil on the fiber surface. did. The obtained purified Tencel fiber (cut yarn) was dispersed in water so as to have a solid content of 1.5% by weight (400 L), and as a disk refiner device, SDR14 type laboratory refiner manufactured by Aikawa Teiko Co., Ltd. (pressurized DISK) Using the formula, 400 L of the aqueous dispersion was beaten for 20 minutes with a clearance between the disks of 1 mm. Subsequently, beating was performed under the condition that the clearance was reduced to a level close to almost zero to obtain a beating water dispersion (solid content concentration: 1.5% by weight). The obtained beating water dispersion was directly subjected to micronization treatment 5 times under an operating pressure of 100 MPa using a high-pressure homogenizer (NS015H manufactured by Niro Soavi Co., Ltd. (Italy)) to obtain an aqueous dispersion M1 of cellulose fibers (solids). Partial concentration: 1.5% by weight in both cases).

Subsequently, after diluting the aqueous dispersion M1 to a solid concentration of 0.1% by weight and dispersing it in a blender, a plain fabric made of PET / nylon blend (manufactured by Shikishima Canvas Co., Ltd., NT20, water at 25 ° C. in air) was used. Permeation amount: 0.03 ml / cm ² · s, batch type paper machine (Kumagaya Riki Kogyo Co., Ltd., automatic square type) set with a cellulose fiber capable of filtering at least 99% by filtration at 25 ° C. under atmospheric pressure The above-prepared papermaking slurry was charged into a sheet machine (25 cm × 25 cm, 80 mesh) using a cellulose sheet having a basis weight of 4 g / m ² as a guide. Thereafter, papermaking (dehydration) was performed at a reduced pressure of 4 KPa with respect to the atmospheric pressure.
The wet paper made of the concentrated composition in a wet state on the obtained filter cloth is peeled off from the wire, and the wet paper surface is brought into contact with the drum surface so that the wet paper / filter cloth is in two layers. The paper is dried for about 120 seconds in a drum dryer set at a temperature of 130 ° C. again so that the wet paper web comes in contact with the drum surface, and the filter cloth is separated from the cellulose sheet-like structure from the obtained dried two-layer body. Thus, a sheet (25 cm × 25 cm) S1 composed of white uniform cellulose fibers shown in Table 1 below was obtained.

[Example 2]
To the papermaking slurry prepared by diluting M1 of Example 1 with water, a papermaking slurry adjusted to give a cellulose sheet having a basis weight of 15 g / m ² was added, and the obtained wet paper was used as a wet paper / filter cloth. A sheet S2 made of white cellulose shown in Table 1 below was obtained in the same manner as in Example 1 except that the two-layer state was dried in a drying oven set at 130 ° C.

[Example 3]
The same operation as in Example 1 was carried out except that the papermaking slurry prepared by diluting M1 in water with water in Example 1 and adjusting to be a cellulose sheet with a basis weight of 50 g / m ² was added. Thus, a sheet S3 made of white cellulose shown in Table 1 below was obtained.

[Example 4]
The same operation as in Example 1 was carried out except that the papermaking slurry prepared by diluting M1 in water with water in Example 1 was adjusted to a cellulose sheet having a basis weight of 100 g / m ^2. Thus, a sheet S4 made of white cellulose shown in Table 1 below was obtained.

[Example 5]
The same operation as in Example 2 was carried out except that the papermaking slurry adjusted in M1 of Example 2 and the hydrophilic polypropylene long-fiber nonwoven fabric having a basis weight of 20 g / m ² obtained from Asahi Kasei Fibers Co., Ltd. were charged. Then, a sheet S5 made of white cellulose shown in Table 1 below was obtained.

[Example 6]
The same operation as in Example 1 was carried out except that the papermaking slurry prepared in M1 of Example 2 and a cellulose long-fiber nonwoven fabric having a basis weight of 17 g / m ² obtained from Asahi Kasei Fibers Co., Ltd. were used. A sheet S6 made of white cellulose shown in Table 1 was obtained.

[Example 7]
Aramid pulp, which is an organic polymer as a raw material, was put in a washing net, a surfactant was added, and the washing was repeated with a washing machine to remove oil on the fiber surface. The obtained purified Tencel fiber (cut yarn) was dispersed in water so as to have a solid content of 1.5% by weight (400 L), and as a disk refiner device, SDR14 type laboratory refiner manufactured by Aikawa Teiko Co., Ltd. (pressurized DISK) Using the formula, 400 L of the aqueous dispersion was beaten for 20 minutes with a clearance between the disks of 1 mm. Subsequently, beating was performed under the condition that the clearance was reduced to a level close to almost zero to obtain a beating water dispersion (solid content concentration: 1.5% by weight). The obtained beating water dispersion was subjected to micronization treatment under an operating pressure of 100 MPa using a high-pressure homogenizer (NS015H manufactured by Niro Soavi Co., Ltd. (Italy)) as it was to obtain an aramid nanofiber aqueous dispersion M2 (solid content concentration). : 1.5% by weight in both cases). Subsequently, water dispersion M1 solid content: water dispersion M2 solid content = 50: 45 as a solid content weight composition, and a solid content concentration of 0.1% by weight were mixed, diluted with water, and then diluted with water. Sheet S7 made of white cellulose shown in Table 1 below was obtained by performing the same operation as in Example 1 except that 5% by weight of the fiber weight was added.

Example 8
Linter pulp, which is natural cellulose as a raw material, is immersed in water so as to have a concentration of 4% by weight, and heat-treated at 130 ° C. for 4 hours in an autoclave. The obtained swollen pulp is washed with water many times and impregnated with water. A swelled pulp in a dried state was obtained. This was continuously beaten in the same manner as in Example 1, and subsequently subjected to fine treatment five times with a high-pressure homogenizer at an operating pressure of 100 MPa to obtain an aqueous dispersion M3 having a solid concentration of 1.5 wt%. Subsequently, the aqueous dispersion M1 solid content: the aqueous dispersion M3 solid content was 55:45, and the solid content concentration was 0.1% by weight as the solid content composition, and the same operation as in Example 1 was performed. Then, a sheet S8 made of white cellulose shown in Table 1 below was obtained.

[Example 9]
A sheet S9 made of white cellulose shown in Table 1 below was obtained in the same manner as in Example 8 except that the basis weight was changed.

[Example 10]
A sheet S10 made of white cellulose shown in Table 1 below was obtained by performing the same operation as in Example 2 except that the number of times of the fine processing was thoroughly performed.

[Example 11]
The water dispersion (solid content: 1.5 wt%) thoroughly beaten and refined obtained in Example 10 was diluted to a solid content of 0.2%. Thereafter, centrifugation was performed at 8,000 rpm for 20 minutes using a centrifuge (KUBOTA 7780). Thereafter, the supernatant liquid generated on the upper part of the aqueous dispersion was separated by decantation. The supernatant was diluted to a solid concentration of 0.1% by weight and dispersed in a blender. A plain fabric made of PET / nylon blend (manufactured by Shikishima Canvas Co., Ltd., NT20, water permeation amount at 25 ° C. under atmospheric pressure: 0.2%) was used. Batch type paper machine (Kumagaya Riki Kogyo Co., Ltd., automatic square sheet machine 25 cm × 25 cm) set with 03 ml / cm ² · s, capable of filtering at least 99% of cellulose fibers by filtration at atmospheric pressure at 25 ° C. , 80 mesh) was prepared in the same manner as in Example 1 except that the above-prepared papermaking slurry was charged with a cellulose sheet having a basis weight of 10 g / m ² as a guide. The obtained sheet S11 was obtained.

[Example 12]
A sheet S12 made of white cellulose shown in Table 1 below was obtained in the same manner as in Example 11 except that the basis weight was changed.

Example 13
The following operation was performed in the same manner as in Example 1 except that the beating was thoroughly performed, the fineness was not changed, and the basis weight was changed as shown in Table 1 below. A sheet S13 made of white cellulose shown in Table 1 was obtained.

[Example 14]
The white cellulose shown in Table 1 below was obtained by performing the same operation as in Example 1 except that the fineness treatment was not performed and the basis weight was changed as shown in Table 1 below. The produced sheet S14 was obtained.

[Comparative Example 1]
Except that an aqueous dispersion M2 of linter, a natural cellulose prepared in Example 7 to a paper slurry prepared by diluting with water, was charged the adjusted papermaking slurry as a cellulosic sheet having a basis weight of 15 g / m ² By performing the same operation as in Example 1, a reference sheet R1 shown in Table 1 below was obtained.

[Seat evaluation]
(1) Composition The raw materials and the content ratios of the sheets prepared in Examples 1 to 14 and Comparative Example 1 are summarized in Table 1 and described.
(2) Measurement of Sample Thickness Using a film thickness meter (Model ID-C112XB) manufactured by Mitutoyo, 10 cm × 10 cm square pieces were cut out of the sheet, and the average value of the measured values at five points at various positions was calculated as the film thickness T. (Μm).
(3) Weight Measurement of Cellulose Sheet The weight per 1 m ² was calculated from the weight W (g) of a 10.0 cm × 10.0 cm square piece cut out in (2) above and calculated from the average value.
(4) Calculation of the porosity of the molded body From the thickness d (μm) and the weight W (g) of the 10.0 cm × 10.0 cm square piece cut in the above (2), the porosity of the film is obtained. Pr (%) was evaluated at five points and calculated from the average value.
(5) Measurement of Fiber Diameter Equivalent to Specific Surface Area After measuring the adsorption amount of nitrogen gas at the boiling point of liquid nitrogen with respect to about 0.2 g of the sheet sample using a specific surface area / pore distribution measuring device (manufactured by Beckman Coulter, Inc.) The specific surface area (m ² / g) was calculated by an apparatus program, and a cylinder model (fiber was converted into a cylinder having a circular cross section) assuming an ideal state in which no fusion occurred between fibers and a cellulose density of 1.50 g / ml. Based on the formula (fiber diameter = 2.67 / specific surface area) introduced from the surface area / volume ratio when the length is ∝, the fiber diameter equivalent to the specific surface area was calculated from the average value of three times evaluation of the specific surface area.
(6) Measurement of Air Permeation Resistance of Membrane Using a Gurley-type densometer (Model G-B2C, manufactured by Toyo Seiki Co., Ltd.), measurement of the permeation time (unit: s / 100 cc) of 100 cc air of the sheet was performed at room temperature. went. As an index of the uniformity of the film, five measurements were made at various positions on the film.
(7) Resin impregnating property 10 μl of an epoxy monomer (Epolite 100MF, manufactured by Kyoeisha Chemical Co., Ltd.) was dropped on the sheet with the composition of Example 1-14 and Comparative Example 1, and the permeability was evaluated. Three minutes after the dropping, the case where the permeation reached the back surface was evaluated as 、, and the case where it did not permeate was evaluated as ×.

[Preparation of composite prepreg film]
[Example 15]
A composite prepreg film was produced by impregnating the sheet S2 with a resin component. A 10 cm square sheet and a 100 μm thick spacer were placed on a PET film coated with a release agent. A mixed solution prepared in advance with stirring and mixing according to the composition shown in Table 2 was dropped on a sheet, and a PET film coated with a release agent was placed thereon. While pressing this sheet from above the PET film at 10 kg / cm ² , vacuum defoaming was allowed to stand for several days at room temperature, whereby a composite prepreg film in which white cellulose shown in Table 2 below was impregnated with an epoxy resin was used. C1 was obtained.

[Name of compound used as composition described in Table 2]
C1
Epoxy resin: Epoxy resin JER825 (Mitsubishi Chemical Corporation)
Curing agent: Latent curing agent Fuji Cure FXE1000 (Fuji Kasei Co., Ltd.)
Inorganic fine particles: Colloidal silica (manufactured by Nissan Chemical Industries, Ltd.)

[Preparation of composite film]
[Examples 16 to 24, Comparative Examples 2 to 4]
A composite film was prepared by impregnating the sheet with a resin component. A 10 cm square sheet and a spacer having a predetermined thickness were placed on a PET film coated with a release agent. The composition and the sheet shown in Table 2 which were previously stirred and mixed were combined, and a PET film coated with a release agent was placed thereon. This sheet was vacuum defoamed while being pressed from above the PET film at 10 kg / cm ² . This was put in a dryer, and cured or melted by heat or ultraviolet irradiation to obtain a composite film C2-10 in which resin was impregnated in white cellulose as shown in Table 2 below, and a reference sheet RC2-4. .

[Name of compound used as composition described in Table 2]
C2
Epoxy resin: Epoxy resin JER828 (Mitsubishi Chemical Corporation)
Curing agent: ST12 (Mitsubishi Chemical Corporation)
C3
Epoxy resin: Epoxy resin JER825 (Mitsubishi Chemical Corporation)
Curing agent: Latent curing agent Fuji Cure FXE1000 (Fuji Kasei Co., Ltd.)
Inorganic fine particles: Colloidal silica (manufactured by Nissan Chemical Industries, Ltd.)
C4
Thermoplastic resin: Polypropylene film C5
Thermoplastic resin: Polypropylene film C6
Epoxy resin: Epoxy resin JER825 (Mitsubishi Chemical Corporation)
Curing agent: Latent curing agent Fuji Cure FXE1000 (Fuji Kasei Co., Ltd.)
Inorganic fine particles: Colloidal silica (manufactured by Nissan Chemical Industries, Ltd.)
C7
Epoxy resin: Epoxy resin JER825 (Mitsubishi Chemical Corporation)
Curing agent: Latent curing agent Fuji Cure FXE1000 (Fuji Kasei Co., Ltd.)
Inorganic fine particles: Colloidal silica (manufactured by Nissan Chemical Industries, Ltd.)
C8
Epoxy resin: Epoxy resin JER825 (Mitsubishi Chemical Corporation)
Curing agent: Latent curing agent Fuji Cure FXE1000 (Fuji Kasei Co., Ltd.)
Inorganic fine particles: Colloidal silica (manufactured by Nissan Chemical Industries, Ltd.)
C9
Epoxy resin: Epoxy resin JER825 (Mitsubishi Chemical Corporation)
Curing agent: Latent curing agent Fuji Cure FXE1000 (Fuji Kasei Co., Ltd.)
Inorganic fine particles: Colloidal silica (manufactured by Nissan Chemical Industries, Ltd.)
RC1
Epoxy resin: Epoxy resin JER828 (Mitsubishi Chemical Corporation)
Curing agent: ST12 (Mitsubishi Chemical Corporation)
RC2
Thermoplastic resin: Polypropylene film RC3
Epoxy resin: Epoxy resin JER828 (Mitsubishi Chemical Corporation)
Curing agent: ST12 (Mitsubishi Chemical Corporation)

[Composite prepreg film evaluation]
(1) Composition In Example 15, the raw materials and the content ratios used for producing the composite prepreg film are summarized and described in Table 2.
(2) Measurement of Sample Thickness Using a film thickness meter (Model ID-C112XB) manufactured by Mitutoyo, a 10 cm × 10 cm square piece was cut from the composite prepreg film, and the average value of the measured values at five points at various positions was determined as the film thickness. d (μm).
(3) Resin impregnating property With the composition of Example 15, 10 μl of an epoxy monomer (Epolite 100MF, manufactured by Kyoeisha Chemical Co., Ltd.) was dropped on the sheet, and the permeability was evaluated. Three minutes after the dropping, the case where the permeation reached the back surface was evaluated as 、, and the case where it did not permeate was evaluated as ×.

"Composite film evaluation"
(1) Composition In Examples 16 to 24 and Comparative Examples 2 to 4, the raw materials and the content ratios used for producing the composite films are summarized and described in Table 2.
(2) Measurement of Sample Thickness Using a film thickness meter (Model ID-C112XB) manufactured by Mitutoyo, 10 cm × 10 cm square pieces were cut from the composite film, and the average value of the measured values at five points at various positions was used as the film thickness d. (Μm).
(3) Resin impregnating property With the composition of Example 14-21 and Comparative example 2-4, 10 μl of an epoxy monomer (Epolite 100MF, manufactured by Kyoeisha Chemical Co., Ltd.) was dropped on the sheet, and the permeability was evaluated. Three minutes after the dropping, the case where the permeation reached the back surface was evaluated as 、, and the case where it did not permeate was evaluated as ×.
(4) Evaluation of Peelability After the composite film was cut out into a strip of 10 cm × 2.5 cm, a cut was made near the composite film core on the short side with a cutter. After that, when the tape was stuck on the surface of the composite film and a 90-degree peel test was performed using the tape, the tape was peeled off from the composite film, and the tape was peeled off at the interface between the core material of the composite film and the resin. The thing that got up was marked X.
(5) Evaluation of coefficient of linear thermal expansion Using the composite film cut out in (2) above, using TMA / SS6100 manufactured by Seiko Instruments Inc., the temperature was raised and lowered at a rate of 10 ° C./min once. Thereafter, the average linear expansion coefficient at 100 to 150 ° C. when the temperature was raised again at a rate of 10 ° C./min was measured.
(6) Evaluation of Improvement of Elastic Modulus A test piece having a width of 10 mm and a length of 60 mm was obtained from the cured resin using a film prepared with a composition of Examples 15 to 24 and Comparative Examples 2 to 4 having a composite film thickness of 2 mm. Was cut out and subjected to three-point bending using an Instron universal testing machine (manufactured by Instron) in accordance with JIS K7171 (1994), and the elastic modulus was measured. The average value of the values measured with the number of samples n = 3 is defined as the value of the elastic modulus, and the elastic modulus of the reference sheets (RC1 and RC2) having no film is improved by 1.2 times or more.た is given to those obtained, and ◎ is given to those showing a remarkable effect of improving the elastic modulus.

[Evaluation]
The composite prepreg film of Example 15 and the composite films of Examples 16 to 24 produced by compounding the sheet obtained in Examples 1 to 14 with each resin had a specific surface area equivalent fiber diameter of 0.20 μm. By using a regenerated cellulose having a size of 2.0 μm or less, a sheet having a large pore diameter and a large porosity can be designed, so that the resin impregnation property of the sheet is high and the composite is easily formed. In addition, by using nanofibers, the effects of improving the releasability, reducing the coefficient of linear thermal expansion, and improving the elastic modulus when combined with a resin were exhibited.
On the other hand, the composite film of Comparative Example 4 produced by combining the films obtained in Comparative Examples 2 and 3 with the resin of Comparative Example 1 has no sheet layer or has a specific surface area equivalent. Since the fiber diameter was 0.1 μm, it was found that the coefficient of linear thermal expansion could not be reduced because the resin was not easily impregnated even when the composite was formed.

  The sheet of the present invention is excellent in resin impregnation because it has a limited range of air permeability, that is, a pore size, although it is a thick film, for example, when used as a core material for fiber-reinforced plastic. Can provide thermal stability (reducing the coefficient of linear thermal expansion and maintaining elasticity at high temperatures) when combined with resin, and when used as a core material for automotive materials, Since the sheet strength can be ensured while being lightweight, it can be suitably used in these fields.

Claims (33)

A sheet comprising at least one cellulose fiber layer containing 50% by weight or more of regenerated cellulose fibers or a plurality of layers of three or less layers, the following requirements:
(1) The fiber constituting the cellulose fiber layer has a fiber diameter equivalent to a specific surface area of 0.20 μm or more and 2.0 μm or less;
(2) the thickness of the cellulose fiber layer is 20 μm or more;
( 3 ) air permeability resistance of the sheet is 1 s / 100 ml or more and 400,000 s / 100 ml or less; and ( 4 ) a film thickness of the sheet is more than 22 μm;
A sheet characterized by satisfying the following.   The sheet according to claim 1, wherein the cellulose fiber layer contains regenerated cellulose fibers in an amount of 70% by weight or more.   The sheet according to claim 1, wherein the air resistance is 5 s / 100 ml or more and 20,000 s / 100 ml or less.   The regenerated cellulose fiber contains at least a micronized cellulose fiber, the specific surface area equivalent fiber diameter of the micronized cellulose fiber is 0.20 μm or more and 2.0 μm or less, and the cellulose fiber layer has a fiber diameter of 3 μm or more and 15 μm or less. The sheet according to any one of claims 1 to 3, wherein the fiber is contained in an amount of more than 0% by weight and 30% by weight or less.   The sheet according to any one of claims 1 to 4, wherein the thickness of the sheet is more than 100 µm.   The sheet according to any one of claims 1 to 5, wherein a fiber diameter corresponding to a specific surface area of a fiber constituting the cellulose fiber layer is 0.20 µm or more and 0.45 µm or less. The sheet according to any one of claims 1 to 6, wherein the basis weight of the cellulose fiber layer is 2 g / m ² or more.   The sheet according to any one of claims 1 to 7, wherein the cellulose fiber layer contains less than 50% by weight of a natural cellulose fiber.   The sheet according to claim 8, wherein the cellulose fiber layer contains less than 30% by weight of natural cellulose fibers.   The sheet according to any one of claims 1 to 7, wherein the cellulose fiber layer contains less than 50% by weight of a fiber made of an organic polymer other than cellulose.   The sheet according to claim 10, wherein the cellulose fiber layer contains less than 30% by weight of a fiber made of an organic polymer other than cellulose.   The sheet according to claim 10, wherein the fiber made of an organic polymer other than cellulose is aramid fiber and / or polyacrylonitrile fiber.   The sheet according to any one of claims 1 to 12, wherein the cellulose fiber layer contains a reactive crosslinking agent at 10% by weight or less. The layer according to any one of claims 1 to 13, wherein the three-layer or less multi-layer structure includes a nonwoven fabric or paper having a basis weight of 5 g / m ² or more and 200 g / m ² or less. Sheet. More and to having a basis weight including the base layer is a nonwoven fabric or paper is 10 g / m ² or more 100 g / m ² or less, a sheet according to claim 14 of the multi-layer structure of the three layers or less.   The method for producing a sheet according to any one of claims 1 to 15, comprising an aqueous papermaking step.   The method for producing a sheet according to any one of claims 1 to 15, further comprising a coating step.   The sheet according to any one of claims 1 to 15, which is used for sound insulation.   (A) A composite film, wherein the sheet according to any one of claims 1 to 15 is impregnated with (B) a resin.   The composite film according to claim 19, wherein the resin (B) is one or more resins selected from the group consisting of a thermosetting resin, a photocuring resin, and a thermoplastic resin.   21. The composite film according to claim 19, wherein the resin (B) is one or more of an epoxy resin, an acrylic resin, and a general-purpose plastic.   The composite film according to any one of claims 19 to 21, wherein the resin (B) contains less than 50% by mass of inorganic fine particles. Wherein the inorganic fine particles _{is SiO 2, TiO 2, Al 2} O 3, ZrO 2, MgO, ZnO, and one or more selected from the group consisting of BaTiO _3, the composite film according to claim 22.   A composite prepreg film comprising (A) the sheet according to any one of claims 1 to 15 and (B) a thermosetting resin and / or a photocurable resin.   The composite prepreg film according to claim 24, wherein the resin (B) is an epoxy resin, an acrylic resin, and / or a polyimide resin.   The composite prepreg film according to claim 24 or 25, wherein the resin (B) contains less than 50% by mass of inorganic fine particles. Wherein the inorganic fine particles _{is SiO 2, TiO 2, Al 2} O 3, ZrO 2, MgO, ZnO, and one or more selected from the group consisting of BaTiO _3, the composite prepreg film according to claim 26.   A core material for a fiber-reinforced plastic film, comprising the sheet according to claim 1.   The core material for a fiber-reinforced plastic film according to claim 28, for an in-vehicle material.   The core material for a fiber-reinforced plastic film according to claim 28, for an electronic material.   A prepreg for a fiber-reinforced plastic film, comprising the sheet according to any one of claims 1 to 15.   A fiber-reinforced plastic film comprising the sheet according to any one of claims 1 to 15.   33. The fiber reinforced plastic film of claim 32 for in-vehicle materials.