JP6520011B2 - Moisture resistant composite sheet comprising a base sheet layer containing fine fibers and an inorganic layer - Google Patents

Description

  The present invention relates to a composite sheet based on a fine fiber-containing sheet. In detail, by using a sheet containing a substituent-introduced fine fiber as a base material and further laminating an inorganic layer or an organic layer, under high temperature and high humidity while taking advantage of the characteristics of the fine fiber containing sheet such as high transparency. The present invention relates to a composite sheet in which coloration and dimensional change are suppressed.

  Currently, glass plates are used for many substrates for organic EL and liquid crystal displays. However, since the glass sheet has high specific gravity, is heavy, is broken, and can not be bent, it is considered difficult to cope with the reduction in weight and flexibility of various displays in the future. Therefore, in recent years, studies using plastic films such as polyimide and polycarbonate have been advanced as substitutes for glass plates. With regard to plastic films, in order to add various functions, studies have been conducted to laminate an anchor coat layer and an inorganic thin film layer to improve the manufacturability and the gas barrier property (Patent Document 1).

  In recent years, fine fibers having a fiber diameter of 1 μm or less, in particular, cellulose fine fibers have attracted attention. Cellulose fine fiber is an aggregate of cellulose crystals having a high elastic modulus and a low thermal expansion coefficient, and a composite with a non-woven fabric or a transparent resin prepared from this fine fiber has high transparency, high elastic modulus, low linear expansion coefficient It has been reported that it has flexible characteristics. Furthermore, as a method of producing cellulose fine fibers having a narrow fiber diameter, a method of introducing a substituent having electrostatic and / or steric functionality into a fiber raw material in order to facilitate the pulverization (fibrillation) of the fiber raw material is disclosed. It is known (for example, patent documents 2-5). Further, not only fiber materials can be easily refined (fibrillated), but also the fine fiber-containing slurry after micronization (fibrillation) has good drainage and dewaterability, and the obtained microfibers and the microfibers contained There is a need to improve sheet yellowing over time and heating yellowing. For this purpose, a method is also studied in which a substituent-introduced fine fiber is refined (disintegrated), and then a substituent introduced in a slurry state is removed (Patent Document 6).

  Furthermore, for the purpose of imparting oxygen barrier property, water vapor barrier property, etc. to the base material of cellulose fine fiber, laminating a layer made of an inorganic compound, containing a thermoplastic resin in the base material, orientation of cellulose And the like have been studied (Patent Documents 7 to 9).

JP, 2012-96551, A JP, 2010-254726, A JP, 2008-308802, A International Publication 2013/073652 Japanese Patent Application Publication No. 2012-511596 International Publication 2013/176049 JP, 2010-125814, A JP, 2011-152693, A JP, 2011-202101, A

  In general, a plastic film has a linear expansion coefficient higher than that of glass, and tends to cause warpage of the film and breakage of the electronic device when forming an electronic device (inorganic material) requiring a high temperature process. In applications where weight reduction and flexibility are important, there is a demand for novel materials having heat resistance and yellowing resistance that have transparency comparable to glass and low linear expansion coefficient, and can withstand various process temperatures.

  On the other hand, there is a dimensional change in a high temperature and high humidity environment as a subject in application to a sheet of an optical member using a fine fiber introduced with a substituent having an electrostatic and / or steric functionality. Although shrinkage due to humidity is largely influenced by the introduced substituent, since hydroxyl group of cellulose is also a factor, it is necessary to block hydroxyl group and to provide a barrier layer.

  According to the study of the present inventors, although a sheet using cellulose fine fibers into which a substituent is introduced has high transparency obtained by the introduction of a substituent, there is a problem that coloring due to high temperature treatment is remarkable. The On the other hand, when the substituent is removed at the stage of the slurry, the dispersibility in water is reduced, and there is a problem that the sheet itself is difficult to be highly transparent even if it is sheeted as it is. However, it has been found that these problems can be overcome by changing the degree of neutralization or removing a substituent after sheet formation. Different conditions may be used to stack different barrier layers, provided that coloration does not occur even at high temperatures. The present invention provides the following.

[1] A composite sheet comprising a base sheet layer containing fine fibers, and an inorganic layer formed on at least one side of the base sheet layer.
[2] The composite sheet according to 1, wherein the fine fiber is a fine fiber into which a substituent having electrostatic and / or steric functionality is introduced.
[3] The composite sheet according to 1 or 2, further comprising an organic layer formed on at least one side of the base sheet layer.
[4] The composite sheet according to any one of 1 to 3, wherein the fine fibers are cellulose fine fibers having an average fiber width of 2 to 1000 nm.
[5] The substituent is at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid and a group derived from sulfuric acid, and the amount of substituents introduced is 0.01 to 2.0 mmol / g The composite sheet according to any one of 1 to 4, which is
[6] The composite sheet according to any one of 1 to 5, wherein the thickness of the base sheet layer is 0.1 to 1200 μm.
[7] The inorganic layer is at least one selected from the group consisting of silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxycarbide and aluminum oxynitride The composite sheet according to any one of 1 to 6, which comprises.
[8] The composite sheet according to any one of 1 to 7, wherein the organic layer comprises a thermosetting resin or a photocurable resin.
[9] Base sheet layer:
(A) obtaining a substituent-introduced fiber into the fiber raw material and (b) mechanically treating the substituent-introduced fiber obtained in step (a) to obtain a substituent-introduced fine fiber and (c) a step (c) manufactured by a manufacturing method having a step of preparing a sheet from the substituent-introduced fine fiber obtained in b) and a step of removing at least a part of the introduced substituent from the sheet obtained in step (d) (d) The composite sheet according to any one of 1 to 8.
[10] The substituent having electrostatic and / or steric functionality is a group derived from phosphoric acid, and after step (a) and before step (c), further (e) substitution 9. The composite sheet according to 9, which is produced by a production method comprising the step of changing the degree of neutralization of the group introduced fiber or the substituent introduced fine fiber.
[11] At least one side of the substrate sheet layer,
The composite sheet according to any one of 1 to 10, wherein an inorganic layer and an organic layer laminated to the inorganic layer are formed, or an organic layer and an inorganic layer laminated to the organic layer are formed.
[12] A flexible display, a solar cell, a lighting element, a display element, a touch panel, a window material or a structural material using the composite sheet according to [11].
[13] A product using the composite sheet according to 1 to 11, or the solar cell, lighting element, display element, touch panel, window material or structural material according to 11.

  According to the present invention, it is possible to construct a composite sheet having a substituent-introduced fine fiber-containing sheet as a substrate, transparency, flexibility, low linear thermal expansion coefficient, and moisture resistance.

Calibration curve for substrate sheet layer. After preparing a non-woven fabric having a known amount of phosphoric acid group and performing fluorescent X-ray analysis, a calibration curve of characteristic X-ray intensity of P atom and the amount of introduced phosphoric acid group was prepared and tested in an experiment. Calibration curve for substrate sheet layer. A non-woven fabric having a known carboxyl group and a Na salt type was prepared, and a calibration curve of characteristic X-ray intensity of the Na atom and the amount of introduced carboxyl group was prepared and used for the experiment.

  In describing the present invention, its embodiments, and its examples, parts and% mean parts by mass and% by mass unless otherwise specified. Also, the numerical range "a to b" includes the values a and b at both ends, unless otherwise specified.

The composite sheet of the present invention is at least
(1) A base sheet layer, and (2) an inorganic layer formed on at least one side of the base sheet layer.

[Base sheet layer]
The base sheet layer in the composite sheet of the present invention contains fine fibers. The fine fiber is preferably a fine fiber into which a substituent having electrostatic and / or steric functionality is introduced.

<Fiber raw material>
Although it does not specifically limit as a fiber raw material for a base material sheet layer, For example, semi-synthetic fiber, a regenerated fiber, etc. are mentioned, such as an organic fiber, an inorganic fiber, a synthetic fiber. Examples of organic fibers include, but are not limited to, fibers derived from natural products such as cellulose, carbon fibers, pulp, chitin, chitosan and the like. Examples of inorganic fibers include, but are not limited to, glass fibers, rock fibers, metal fibers and the like. Examples of synthetic fibers include, but are not limited to, nylon, vinylon, vinylidene, polyester, polyolefin (for example, polyethylene, polypropylene and the like), polyurethane, acrylic, polyvinyl chloride, aramid and the like. Semi-synthetic fibers include, but are not limited to, acetate, triacetate, promix, and the like. Examples of the regenerated fiber include, but not limited to, rayon, cupra, polynozic rayon, lyocell, tencel and the like.

  Further, the fiber raw material used in the present invention is not particularly limited, but it is desirable to contain a hydroxyl group or an amino group because introduction of a substituent described later becomes easy.

  The fiber material is not particularly limited, but it is preferable to use pulp in terms of availability and low cost. The pulp is selected from wood pulp, non-wood pulp and deinked pulp. Examples of wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), soda pulp (AP), unbleached kraft pulp (UKP), oxygen bleached kraft pulp (OKP), etc. Chemical pulp etc. are mentioned. Also, semi-chemical pulp such as semi-chemical pulp (SCP), chemiground wood pulp (CGP), mechanical pulp such as ground pulp (GP), thermo-mechanical pulp (TMP, BCTMP), etc. may be mentioned, but not particularly limited. . Non-wood pulps include cotton-based pulps such as cotton linters and cotton lint, non-wood-based pulps such as hemp, wheat straw and bagasse, celluloses isolated from ascidians and seaweeds, chitin and chitosan . Examples of the deinked pulp include, but not particularly limited to, deinked pulp made from waste paper. The pulp of the present invention may be used alone or in combination of two or more. Among the above-mentioned pulps, wood pulps containing cellulose and deinked pulps are preferable in terms of availability. Among wood pulps, chemical pulp has a large ratio of cellulose, so the yield of fine cellulose fibers is high at the time of fiber refining (fibrillation), and decomposition of cellulose in the pulp is small, and fine fibers of long fibers having a large axial ratio Although it is especially preferable at the point from which a cellulose fiber is obtained, it does not specifically limit. Among them, kraft pulp and sulfite pulp are most preferably selected, but are not particularly limited. A sheet containing fine cellulose fibers of long fibers having a large axial ratio can obtain high strength.

<Substituents Having Electrostatic and / or Steric Functionality>
It does not specifically limit as a compound which reacts with a fiber raw material. For example, a compound having a group derived from phosphoric acid, a compound having a group derived from carboxylic acid, a compound having a group derived from sulfuric acid, a compound having a group derived from sulfonic acid, a compound having an alkyl group having 10 or more carbon atoms, an amine And the like. Preferred are compounds having at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid and a group derived from sulfuric acid from the viewpoint of ease of handling and reactivity with fine fibers. It is more preferable that these compounds form an ester or / and an amide with the fine fiber, but it is not particularly limited.

Although the introduction amount (by titration method) of the substituent in the substituent-introduced fiber is not particularly limited, 0.005α to 0.11α is preferable per 1 g (mass) of fiber, and 0.01α to 0.08α is more preferable. When the introduction amount of the substituent is less than 0.005α, it is difficult to make the fiber material finer (fibrillation) in the step (b) described later. If the introduced amount of the substituent exceeds 0.11α, the fiber may be dissolved. Here, α is an amount (unit: mmol / g) in which a functional group to which a compound reactive with the fiber material can react, such as a hydroxyl group or an amino group, is contained per 1 g of the fiber material. In addition, the measurement of the introduction amount (titration method) of the substituent on the fiber surface can be carried out by the following method, unless otherwise specified:
A fine fiber-containing slurry containing a solid content of about 0.04 g in bone dry mass is fractionated and diluted to about 50 g with ion exchanged water. While stirring this solution, measure the change of the value of electric conductivity when 0.01 N aqueous sodium hydroxide solution is added dropwise, and the amount of 0.01 N aqueous sodium hydroxide solution dropped when the value becomes minimum. , And the dropping amount at the titration end point. The amount of substituents X on the cellulose surface is represented by X (mmol / g) = 0.01 (mol / l) × V (ml) / W (g). Here, V: a dropping amount (ml) of a 0.01 N aqueous solution of sodium hydroxide, and W: solid content (g) contained in the fine cellulose fiber-containing slurry.

  When the substituent to be introduced is at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid, and a group derived from sulfuric acid, the amount of introduced substituent is not particularly limited. It can be set to 001 to 5.0 mmol / g. It is good also as 0.005-4.0 mmol / g, and good also as 0.01-2.0 mmol / g.

  In one embodiment of the present invention, after forming the substituent-introduced fiber into a sheet, the substituent introduced in step (d) to be described later can be treated to be eliminated to a desired degree. The amount of introduced substituent is not particularly limited, and is, for example, 70% or less, preferably 50% or less, more preferably 30% or less at the time of introduction. Or a process (d) can be performed until it becomes 0.7 mmol / g or less as introduction | transduction amount of the substituent of the sheet | seat after detachment | desorption. It is preferable to carry out until it becomes 0.5 mmol or less, It is more preferable to carry out until it becomes 0.1 mmol / g or less, and it is more preferable to carry out until it becomes 0.047 mmol / g. A smaller amount of substituent content can suppress yellowing and the like when the sheet is heated. In the present invention, the term “substituent introduction amount” in the base sheet layer means a value measured by X-ray fluorescence analysis unless otherwise specified. In the measurement, if necessary, a sheet with a known amount of introduced substituent can be prepared, and the characteristic X-ray intensity of an appropriate atom can be plotted against the amount of introduced substituent to prepare and use a calibration curve. . The detailed measurement method can be referred to the section of Examples in the present specification. In addition, regarding the composite sheet and base sheet layer of the present invention, when the substituent introduction amount is referred to, the amount of the substituent of the composite sheet or the base sheet layer as the final product, ie, the step In the case of d), it refers to the amount of substituents after elimination.

<Fiber width, etc>
The fiber width of the substituent-introduced fine fiber is not particularly limited, but may be, for example, 1 to 1000 nm, preferably 2 to 1000 nm, more preferably 2 to 500 nm, and still more preferably 3 to 100 nm. When the fiber width of the fine fiber is less than 1 nm, the molecule is dissolved in water, so that the physical properties (strength, rigidity, dimensional stability) as the fine fiber can not be expressed. On the other hand, if it exceeds 1000 nm, it can not be said that it is a fine fiber, and the physical properties (strength, rigidity, dimensional stability) as a fine fiber can not be obtained.

  In applications where transparency is required for fine fibers, when the fiber width exceeds 30 nm, it approaches 1/10 of the wavelength of visible light, and when combined with a matrix material, refraction and scattering of visible light are likely to occur at the interface And transparency tends to decrease. Therefore, the fiber width is not particularly limited, but is preferably 2 nm to 30 nm, and more preferably 2 to 20 nm. Composites obtained from such fine fibers as described above generally have high strength because they form a compact structure, and high transparency can also be obtained because there is little scattering of visible light.

The measurement of the fiber width of the fine fiber is performed as follows. A fine fiber-containing slurry having a concentration of 0.05 to 0.1% by mass is prepared, and the slurry is cast on a hydrophilized carbon film-coated grid to obtain a sample for TEM observation. In the case of containing wide fibers, an SEM image of the surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, 20000 times or 50000 times depending on the width of the fiber to be constructed. However, the sample, observation conditions and magnification are adjusted to satisfy the following conditions.
(1) One straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers cross the straight line X.
(2) Draw a straight line Y intersecting perpendicularly with the straight line in the same image, and 20 or more fibers cross the straight line Y.
With respect to the observation image satisfying the above conditions, the width of the fiber intersecting with the straight line X and the straight line Y is visually read. Thus, three or more sets of images of at least non-overlapping surface portions are observed, and for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. Thus, a fiber width of at least 20 x 2 x 3 = 120 is read. The fiber width in the present invention is an average value of the fiber widths read in this manner.

  The fiber length of the fine fiber is not particularly limited, but is preferably 0.1 μm or more. If the fiber length is less than 0.1 μm, it is difficult to obtain the strength improvement effect when the fine fiber is combined with the resin. The fiber length can be determined from image analysis of TEM, SEM, AFM. The said fiber length is a fiber length which occupies 30 mass% or more of a fine fiber.

  The axial ratio (fiber length / fiber width) of the fine fibers is not particularly limited, but is preferably in the range of 20 to 10,000. If the axial ratio is less than 20, it may be difficult to form the base sheet layer. When the axial ratio exceeds 10000, the viscosity of the slurry becomes high, which is not preferable.

<Thickness>
The thickness of the base sheet layer is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, and still more preferably 10 μm or more. From the viewpoints of transparency and flexibility, the thickness of the base sheet layer can be 1200 μm or less, may be 1000 μm or less, may be 500 μm or less, and may be 250 μm or less.

<Method of manufacturing base sheet layer>
The substrate sheet can be manufactured by a manufacturing method comprising at least the following:
(A) introducing a substituent having electrostatic and / or steric functionality into a fine fiber raw material to obtain a substituent-introduced fiber, and (b) mechanically processing the substituent-introduced fiber (c B) preparing a sheet from the machine-treated substituent-introduced fiber and (d) removing at least a part of the introduced substituent from the sheet, or treating the sheet with a polyhydric alcohol to remove the introduced substituent It has a process.

[Step (a)]
Step (a) is a step of introducing a substituent having electrostatic and / or steric functionality into the fiber material to obtain a substituent-introduced fiber. The step (a) is not particularly limited, but it is possible to introduce the above-mentioned substituent into the fiber material by mixing a compound which reacts with the fiber material with the dry or wet fiber material. . A heating method is particularly effective to promote the reaction upon introduction. Although the heat processing temperature in introduction of a substituent is not specifically limited, It is preferable that it is a temperature zone which thermal decomposition, hydrolysis, etc. of this fiber raw material do not occur easily. For example, when a fiber raw material containing cellulose as a fiber raw material is selected, it is preferably 250 ° C. or less from the viewpoint of thermal decomposition temperature, and heat treated at 100 to 170 ° C. from the viewpoint of suppressing hydrolysis of cellulose. preferable.

  When a compound having a group derived from phosphoric acid is used as the compound that reacts with the fiber raw material, it is not particularly limited, but it is composed of phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid or salts or esters thereof It is at least one selected from the group. Among these, compounds having a phosphoric acid group are preferable because they are low in cost, easy to handle, and can further improve the refining (disintegration) efficiency by introducing a phosphoric acid group into the fiber raw material, but are not particularly limited. .

The compound having a phosphoric acid group is not particularly limited, but includes phosphoric acid, lithium dihydrogen phosphate which is a lithium salt of phosphoric acid, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate and lithium polyphosphate . Furthermore, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate and sodium polyphosphate which are sodium salts of phosphoric acid can be mentioned. Furthermore, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate and potassium polyphosphate which are potassium salts of phosphoric acid can be mentioned. Furthermore, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium polyphosphate and the like which are ammonium salts of phosphoric acid can be mentioned.
Among these, phosphoric acid, a sodium salt of phosphoric acid, a potassium salt of phosphoric acid, and an ammonium salt of phosphoric acid are preferable from the viewpoint of high efficiency of phosphoric acid group introduction and industrially easy application, sodium dihydrogenphosphate And disodium hydrogen phosphate are more preferable, but not particularly limited.

  Moreover, although it is preferable to use a compound as aqueous solution from the uniformity of reaction, and the introduction | transduction efficiency of group derived from phosphoric acid being high, it is not specifically limited. The pH of the aqueous solution of the compound is not particularly limited, but is preferably 7 or less because the efficiency of introducing a phosphoric acid group is high. Although the pH of 3 to 7 is particularly preferable from the viewpoint of suppressing the hydrolysis of the fiber, it is not particularly limited.

  When a compound having a group derived from a carboxylic acid is used as a compound which reacts with a fiber material, it is not particularly limited, but a compound having a carboxyl group, an acid anhydride of a compound having a carboxyl group and derivatives thereof It is at least one selected.

  The compound having a carboxyl group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. .

  The acid anhydride of the compound having a carboxyl group is not particularly limited, but acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, itaconic anhydride and the like can be mentioned. Be

  Although it does not specifically limit as a derivative of the compound which has a carboxyl group, The imidate of the acid anhydride of the compound which has a carboxyl group, The derivative of the acid anhydride of the compound which has a carboxyl group is mentioned. Although it does not specifically limit as an imide compound of the acid anhydride of the compound which has a carboxyl group, The imidate of dicarboxylic acid compounds, such as maleimide, a succinimide, phthalimide, is mentioned.

  The acid anhydride derivative of the compound having a carboxyl group is not particularly limited. For example, at least a part of hydrogen atoms of an acid anhydride of a compound having a carboxyl group such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride and the like have a substituent (for example, an alkyl group, a phenyl group, etc. And the like.

  Among compounds having a group derived from a carboxylic acid, maleic anhydride, succinic anhydride and phthalic anhydride are preferable because they are industrially easily applied and gasified easily, but are not particularly limited.

  When a compound having a group derived from sulfuric acid is used as the compound that reacts with the fiber raw material, it is not particularly limited, but it is at least one selected from the group consisting of sulfuric anhydride, sulfuric acid and salts and esters thereof. Among these, sulfuric acid is preferable because it is low in cost and sulfuric acid is introduced into the fiber raw material to further improve the refining (disintegration) efficiency, although not particularly limited.

  By introducing a substituent into the fiber raw material in the step (a), the dispersibility of the fiber in the solution can be improved, and the disaggregation efficiency can be enhanced.

[Step (b)]
The step (b) is a step of subjecting the substituent-introduced fiber obtained in the step (a) to micronization (fibrillation) processing using a defibration treatment apparatus to obtain a substituent-introduced fine fiber.

  The defibration treatment apparatus is not particularly limited. For example, high-speed fibrillation machines, grinders (miller mills), high-pressure homogenizers and ultra-high pressure homogenizers, Creamix, high-pressure collision mills, ball mills, bead mills, disc refiners, conical refiners, etc. may be mentioned. In addition, an apparatus such as a twin-screw kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic dispersion machine, a beater, etc. can be suitably used.

  At the time of the defibration treatment, it is preferable to dilute the substituent-introduced fiber obtained in the step (a) to form a slurry by diluting water and an organic solvent singly or in combination, but it is not particularly limited. The solid content concentration of the substituent-introduced fiber after dilution is not particularly limited, but is preferably 0.1 to 20% by mass, and more preferably 0.5 to 10% by mass. If the solid content concentration of the substituent-introduced fiber after dilution is equal to or higher than the lower limit value, the efficiency of the defibration treatment is improved, and if it is equal to or less than the upper limit value, clogging in the defibration treatment device can be prevented. The dispersion medium is not particularly limited, but in addition to water, polar organic solvents can be used. Preferred polar organic solvents include, but are not limited to, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butyl alcohol. Furthermore, ketones such as acetone and methyl ethyl ketone (MEK), ethers such as diethyl ether and tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethyl acetamide (DMAc) and the like can be mentioned. These may be one kind or two or more kinds. Moreover, in addition to said water and a polar organic solvent, you may use a nonpolar organic solvent if it is a range which does not prevent the dispersion stability of a fine fiber containing slurry.

  The content of the fine fibers in the fine fiber-containing slurry after the refining (fibrillation) treatment is not particularly limited, but is preferably 0.02 to 10% by mass, and more preferably 0.1 to 5% by mass preferable. If the content of the fine fibers is in the above range, the production efficiency at the time of producing the sheet described later is excellent, and the dispersion stability of the slurry is excellent.

[Step (c)]
Step (c) is a step of preparing the substituent-introduced fine fiber obtained in step (b) into a base sheet layer.

  The base sheet layer is not particularly limited, but the fine fibers and fibers other than the fine fibers (hereinafter, referred to as "additional fibers") can also be prepared by mixing at least one or more kinds. Examples of the additional fibers include, but are not particularly limited to, inorganic fibers, organic fibers, synthetic fibers and the like, semi-synthetic fibers, and regenerated fibers. Examples of inorganic fibers include, but are not limited to, glass fibers, rock fibers, metal fibers and the like. Examples of organic fibers include, but are not limited to, fibers derived from natural products such as cellulose, carbon fibers, pulp, chitin, chitosan and the like. Examples of synthetic fibers include, but are not limited to, nylon, vinylon, vinylidene, polyester, polyolefin (for example, polyethylene, polypropylene and the like), polyurethane, acrylic, polyvinyl chloride, aramid and the like. Semi-synthetic fibers include, but are not limited to, acetate, triacetate, promix, and the like. Examples of the regenerated fiber include, but not limited to, rayon, cupra, polynozic rayon, lyocell, tencel and the like. The additional fibers can be subjected to treatments such as chemical treatment and defibration treatment as required. When the additional fiber is treated with chemical treatment or defibration treatment, it may be mixed with the fine fiber and then treated with chemical treatment, defibration treatment or the like, or the additional fiber may be chemically treated with disintegration treatment. It can be mixed with the fine fiber after being subjected to a treatment such as treatment. When the additional fiber is mixed, the addition amount of the additional fiber in the total amount of the fine fiber and the additional fiber is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30 It is less than mass%. Particularly preferably, it is at most 20% by mass.

  A hydrophilic polymer may be added at the time of preparation of a substrate sheet layer. The hydrophilic polymer is not particularly limited. For example, polyethylene glycol, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose etc.), casein, dextrin, starch, modified starch etc. may be mentioned. In addition, polyvinyl alcohol and modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol and the like) can be mentioned. Furthermore, polyethylene oxide, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylates, polyacrylamide, alkyl acrylate copolymer, urethane copolymer and the like can be mentioned.

  Also, instead of hydrophilic polymers, hydrophilic low molecular weight compounds can also be used. The hydrophilic low molecular weight compound is not particularly limited. For example, glycerin, erythritol, xylitol, sorbitol, galactitol, mannitol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol and the like can be mentioned. The addition amount in the case of adding a hydrophilic polymer or a hydrophilic low molecular weight compound is not particularly limited. For example, the amount is 1 to 200 parts by mass, preferably 1 to 150 parts by mass, more preferably 2 to 120 parts by mass, and still more preferably 3 to 100 parts by mass with respect to 100 parts by mass of the solid content of the fine fiber.

  The preparation of the base sheet layer is not particularly limited, but can typically be based on the following papermaking method, coating method and the like.

[Papermaking method]
The fine fiber-containing slurry is used in ordinary papermaking in addition to continuous paper machines such as long net type, circular net type, inclined type etc., multilayer papermaking machine combining these, and further known paper making methods such as hand paper making etc. It is possible to make a sheet and make it into a sheet in the same manner as general paper. That is, after the fine fiber-containing slurry is filtered and dewatered on a wire to obtain a wet paper sheet, it is possible to obtain a sheet by pressing and drying. The concentration of the slurry is not particularly limited, but is preferably 0.05 to 5% by mass. If the concentration is too low, it takes an enormous amount of time to filter, and conversely, if the concentration is too high, uniform sheets can not be obtained. When the slurry is filtered and dewatered, it is not particularly limited as a filter cloth at the time of filtration, but it is important that fine fibers do not pass and the filtration rate does not become too slow. Such a filter cloth is not particularly limited, but a sheet made of an organic polymer, a woven fabric, and a porous membrane are preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and the like are preferable. Specific examples thereof include porous films of polytetrafluoroethylene with a pore diameter of 0.1 to 20 μm, for example, 1 μm, and woven fabrics of polyethylene terephthalate or polyethylene with a pore diameter of 0.1 to 20 μm, for example 1 μm.

  It does not specifically limit as a method to manufacture a sheet from the slurry containing a fine fiber. For example, the method described in WO2011 / 2013567 and the like can be mentioned. Specifically, by using the following manufacturing apparatus. A water squeezing section for discharging a slurry containing fine cellulose fibers onto the upper surface of an endless belt and squeezing a dispersion medium from the squeezed slurry to form a web, and a drying section for drying the web to form a fiber sheet And The endless belt is disposed from the water squeezing section to the drying section, and the web generated in the water squeezing section is conveyed to the drying section while being placed on the endless belt.

  The dehydrating method which can be used is not particularly limited, and the dehydrating method usually used in the production of paper may be mentioned, and the method of dehydrating with a long mesh, circular mesh, inclined wire or the like and then dehydrating with a roll press is preferred. Further, the drying method is not particularly limited, and examples thereof include methods used in the production of paper. For example, methods such as a cylinder drier, a Yankee drier, hot air drying, an infrared heater and the like are preferable.

[Coating method]
The coating method is a method of obtaining a sheet by coating a fine fiber-containing slurry on a substrate and drying it to peel off the fine fiber-containing layer formed from the substrate. A sheet can be continuously produced by using a coating device and a long base material. The quality of the substrate is not particularly limited, but a material having high wettability to the fine fiber-containing slurry may be capable of suppressing shrinkage of the sheet during drying, but the sheet formed after drying may be easily peeled off. It is preferable to choose what can be done. Among them, a resin plate or a metal plate is preferable, but it is not particularly limited. Among them, suitable ones are preferably used alone or laminated, but are not particularly limited. For example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polyvinylidene chloride plates, etc., metal plates such as aluminum plates, zinc plates, copper plates, iron plates and the like, and their surfaces oxidized. A stainless steel plate, a brass plate, etc. can be used. In order to apply the fine fiber-containing slurry onto the substrate, various coaters capable of applying a predetermined amount of slurry to the substrate may be used, but are not particularly limited. For example, a roll coater, a gravure coater, a die coater, a curtain coater, a spray coater, a blade coater, a rod coater, an air doctor coater or the like can be used. Above all, coating methods such as a die coater, a curtain coater, a spray coater and an air doctor coater are effective for uniform coating.

  The drying method is not particularly limited, but it may be either a non-contact drying method or a method of drying while restraining the sheet, or a combination thereof.

  The non-contact drying method is not particularly limited, but a method of heating and drying by hot air, infrared rays, far infrared rays or near infrared rays (heat drying method), a method of vacuum drying (vacuum drying method) may be applied. Can. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Drying by infrared light, far infrared light or near infrared light can be performed using an infrared light device, a far infrared light device or a near infrared light device, but is not particularly limited. The heating temperature in the heating and drying method is not particularly limited, but is preferably 40 to 120 ° C., and more preferably 40 to 105 ° C. When the heating temperature is at least the lower limit value, the dispersion medium can be volatilized quickly, and if it is at most the upper limit value, the cost required for heating can be suppressed, and discoloration of the fine fibers due to heat can be suppressed.

[Step (d)]
Step (d) is a step of removing all or part of the introduced substituents from the base sheet layer obtained in step (c). In the present invention, after the fibrils into which the substituent produced in the above step is introduced are sheeted, the substituent introduced into the fibril contained in the sheet is removed.

An alcohol is used when removing a substituent in step (d). It is preferable to use a polyhydric alcohol from the viewpoint of high ability to separate. Polyhydric alcohol refers to alcohol having two or more OH groups. When a polyhydric alcohol is used, it is preferable to use one having an OH / C ratio of 0.15 or more. More preferably, it is 0.2 or more. The “OH / C ratio” refers to the number of OH groups per carbon (C) atom contained in the molecule, for example, the OH / C ratio of ethylene glycol (C ₂ H ₆ O ₂ ) is 1, and diethylene glycol The OH / C ratio of (C ₄ H ₁₀ O ₃ ) is 0.67.

  Examples of polyhydric alcohols having an OH / C ratio of 0.2 or more include ethylene glycol, diethylene glycol, propylene glycol (1,2-propanediol), glycerin (glycerol, 1,2,3-propanetriol) It is. Other examples are pentanediol, octanediol, decanediol, sugar alcohols (eg sorbitol, lactitol, maltitol, mannitol, xylitol).

  The amount of alcohol used in the step (d) is not particularly limited as long as the elimination of the substituent can be sufficiently performed, but can be appropriately determined based on the sheet weight. Also when using any alcohol, 1-100 mass parts of alcohol can be used with respect to 1 mass part of sheets, for example. If the amount of alcohol used is less than 1 part by mass with respect to 1 part by mass of the sheet, desorption may not be sufficiently performed.

  The temperature at which the step (d) is performed is not particularly limited as long as desorption of the substituent can be sufficiently performed, but may be 140 ° C. or higher, preferably 160 ° C. or higher, and more preferably 170 ° C. or higher. However, it is preferable to select a temperature at which the decomposition of the fiber raw material is suppressed, and is not particularly limited. For example, when cellulose is used as the fiber raw material, it is 250 ° C. or less, more preferably 200 ° C. or less. In addition, when heating, additives such as acid or base may be added as appropriate.

  The time for performing step (d) is not particularly limited as long as the elimination of the substituent can be sufficiently performed. For example, when using glycerin which is a polyhydric alcohol having an OH / C ratio of 1 as the alcohol and carried out at 180 ° C., it can be 10 to 120 minutes, preferably 15 to 90 minutes, and more preferably 15 to 60 minutes. preferable. The same can be said for other alcohols.

Step (d) can be carried out until the introduced substituent is eliminated to the desired degree. The amount of the substituent after elimination is not particularly limited, and is, for example, 70% or less, preferably 50% or less, more preferably 30% or less at the time of introduction. Or a process (d) can be performed until it becomes 0.7 mmol / g or less as introduction | transduction amount of the substituent of the sheet | seat after detachment | desorption. It is preferable to carry out until it becomes 0.5 mmol or less, It is more preferable to carry out until it becomes 0.1 mmol / g or less, and it is more preferable to carry out until it becomes 0.047 mmol / g. A smaller amount of substituent content can suppress yellowing and the like when the sheet is heated. In the present invention, the term “substituent introduction amount” in the base sheet layer means a value measured by X-ray fluorescence analysis unless otherwise specified. In the measurement, if necessary, a sheet with a known amount of introduced substituent can be prepared, and the characteristic X-ray intensity of an appropriate atom can be plotted against the amount of introduced substituent to prepare and use a calibration curve. . The detailed measurement method can be referred to the section of Examples in the present specification.
[Step (e)]
In one embodiment of the present invention, a phosphoric acid group is introduced as a substituent having electrostatic and / or steric functionality to the fiber material. In this case, the step (a) may further include the step of changing the degree of neutralization of the substituent-introduced fiber or the substituent-introduced fiber after the step (a) and before the step (c). When the phosphate group is introduced into the fiber, the degree of neutralization is usually 2 (also referred to as the degree of neutralization 100%).

For example, when a phosphoric acid group is introduced into a cellulose fiber using a sodium salt of phosphoric acid, the state of neutralization degree 2 (100% neutralization degree) after introduction is cellulose-O-P (= O) (- ^{O - Na +) (- O} - Na +) is represented as. In the case of performing substituent removal using an alcohol in step (d), it is preferable that the electron pair on the hydroxyl group possessed by the alcohol be susceptible to nucleophilic attack on the phosphorus of the phosphate group. When the degree of neutralization is 2 (100% degree of neutralization), the phosphate group has a strong negative charge and is less susceptible to nucleophilic attack. The cellulose -O-P (= O) ( - O - H +) in the state of (- ^- O H ⁺⁾ and the degree of neutralization represented 0 (neutralization degree of 0%), hydrogen between phosphate groups Bonding becomes strong, making it difficult to attack nucleophiles. Therefore, by changing the degree of neutralization, the influence of the negative charge amount of the phosphate group and the hydrogen bond between the phosphate groups can be reduced, and the desorption efficiency of the substituent is improved. In this specification, the case where cellulose fiber is used as an example of fiber may be described as an example, but those skilled in the art can apply the description to the case where other types of fiber are used. I can understand.

The means for changing the degree of neutralization in the step (e) is not particularly limited. For example, ion exchange treatment may be carried out by using fine fibers having a degree of neutralization of 2 (100% degree of neutralization) as a suspension. . The ion exchange treatment is also preferable from the viewpoint that a desired effect is sufficiently obtained and the operation is simple. In the ion exchange treatment, a cation exchange resin is used. In addition, H ⁺ ion is usually used as a counter ion. By treating with an appropriate amount of cation exchange resin for a sufficient time, fine fibers with a degree of neutralization of 0 (degree of neutralization 0%) can be obtained. Mixing the obtained fine fibers of degree of neutralization 0 (degree of neutralization 0%) with fine fibers of degree of neutralization 2 (degree of neutralization 100%) without changing the degree of neutralization at an appropriate ratio Thus, fine fibers with various degrees of neutralization between 0 (degree of neutralization 0%) and 2 (degree of neutralization 100%) can be obtained.

  In the ion exchange treatment, either a strongly acidic ion exchange resin or a weakly acidic ion exchange resin can be used, but it is preferable to use a strongly acidic one. Specifically, a styrene resin or an acrylic resin into which a sulfonic acid group or a carboxy group is introduced can be used. The shape of the ion exchange resin is not particularly limited, and various materials such as fine particles (granular particles), membranes, fibers, liquids, etc. can be used, but from the viewpoint of efficiently treating the fine fiber suspension. Is preferably granular. As a specific example, commercially available Amberjet 1020, 1024, 1060, 1220 (Organo Co., Ltd.) may be mentioned. Other examples include Amberlite IR-200C, IR-120B (above, Tokyo Organic Chemical Co., Ltd.), Levatit SP 112, S100 (manufactured by Bayer), GEL CK 08 P (Mitsubishi Chemical), Dowex 50W- X8 (Dow Chemical) and the like.

 Specifically, in the ion exchange treatment, a particulate ion exchange resin and a fiber suspension (slurry) were mixed, and the ion exchange resin was brought into contact with the fine fibers for a certain time while stirring and shaking as necessary. Then, by separating the ion exchange resin and the slurry.

  When treating with an ion exchange resin, the concentration of the fiber suspension (slurry) and the ratio to the ion exchange resin are not particularly limited, and a person skilled in the art can appropriately perform the ion exchange efficiently. It can be designed. The concentration may be such that processing for forming a sheet is easy in the subsequent steps. Specifically, the concentration of the slurry is preferably 0.05 to 5% by mass. When the concentration is too low, processing takes time, and conversely, when the concentration is too high, a sufficient ion exchange effect can not be obtained, which is not preferable. When a slurry having such a concentration range is used, for example, a strongly acidic ion exchange resin having an apparent density of 800 to 830 g / L-R, a water holding capacity of 36 to 55%, and a total exchange capacity of 1.8 eq / L-R is used. . At this time, 1/50 to 1/5 ion exchange resin can be used with respect to the slurry volume 1. The treatment time is also not particularly limited, and can be appropriately designed by those skilled in the art from the viewpoint of efficiently performing ion exchange. For example, it can process for 0.25 to 4 hours.

  Step (e) can be carried out until the degree of neutralization is altered to the desired degree. Also, as described above, the degree of neutralization is adjusted by mixing fibers of degree of neutralization 2 (degree of neutralization 100%) with fibers of degree of neutralization 0 (degree of neutralization 0%) at an appropriate ratio. May be In any case, the degree of neutralization can be 0 (degree of neutralization 0%) to 2 (degree of neutralization 100%), 0.3 (degree of neutralization 15%) to 2 (neutralization) The degree is preferably 100%, and more preferably 0.3 (degree of neutralization 15%) to 1.7 (degree of neutralization 85%).

[Other process]
In the present invention, in addition to the above steps (a) to (d), if necessary, other steps such as a washing step may be performed before each step, before step (a) or after step (d). Although it may have it suitably, it is not limited in particular. For example, although a foreign substance removal process may be employed upstream of the process (b), and a purification process such as centrifugation may be employed downstream of the process (b), it is not particularly limited. The desalting step is preferred in that the purity of the fine fiber is increased. When the desalting step is performed, the means is not particularly limited, and examples include washing by filtration, dialysis, and ion exchange.

  In the method of Patent Document 6 mentioned above, the dispersibility in water is inferior because the substituent is eliminated from the fine fibers in the form of a slurry before the base sheet layer is prepared. May occur. In such a case, a redispersion step can be added, but in the present invention, in which the removal of substituents is performed after sheeting, the substituent is maintained in water without the addition of this redispersion step. Thus, the dispersing effect of the fine fibers by the substituent is sufficiently exhibited.

[Inorganic layer]
The composite sheet of the present invention has an inorganic layer formed on at least one side of the base sheet layer. The inorganic layer may be formed only on one side of the base sheet layer, or may be formed on both sides. In addition, it may be formed in contact with the base sheet layer, or may be formed with another layer, for example, an organic layer described later interposed between the base sheet layer and the base sheet layer. The inorganic layer may be at least one layer formed, and may be stacked as a plurality of layers.

<Material>
The material constituting the inorganic layer is not particularly limited, but, for example, aluminum, silicon, magnesium, zinc, tin, nickel, titanium; their oxides, carbides, nitrides, oxidized carbides, oxynitrides, or oxycarbonitriding Or mixtures thereof. Silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxynitride carbonitride, aluminum oxide, aluminum nitride, aluminum oxycarbide, aluminum oxynitride, or these from the viewpoint that high moisture resistance can be stably maintained. Mixtures are preferred.

<Formation method>
The method of forming the inorganic layer is not particularly limited. Generally, methods for forming thin films are roughly classified into chemical vapor deposition (CVD) and physical vapor deposition (PVD), both of which can be applied for the present invention. . Specific examples of the CVD method include plasma CVD using plasma, and catalytic chemical vapor deposition (Cat-CVD) which catalytically decomposes a material gas using a heating catalyst. Specifically as a PVD method, vacuum evaporation, ion plating, sputtering etc. are mentioned.

  On the other hand, in atomic layer deposition (ALD), a thin film is formed on an atomic layer basis by alternately supplying source gases of the respective elements constituting the film to be formed on the surface forming the layer. How to Although there is a disadvantage that the deposition rate is slow, there is an advantage over the plasma CVD method that it can cleanly cover even complex shapes and can deposit a thin film with few defects. In addition, the ALD method has an advantage that the film thickness can be controlled in nano order, and covering a wide surface is relatively easy. Furthermore, the ALD method can be expected to improve the reaction rate, reduce the temperature to a low temperature, and reduce the unreacted gas by using plasma.

  From the viewpoint of obtaining a uniform thin film having high gas barrier properties, the method of forming an inorganic layer for the present invention is preferably a CVD method, and more preferably an ALD method.

The conditions for forming the inorganic layer can be appropriately designed by those skilled in the art. In the case of a substrate sheet layer subjected to the neutralization treatment of the above step (e) and the desorption treatment of the step (d), since yellowing under high temperature and humidity is suppressed, various conditions are made inorganic without problems. It can be adopted for the membrane. For example, when an inorganic layer of aluminum oxide is applied to a substrate sheet layer subjected to a substituent elimination treatment, trimethylaluminum (TMA) is used as an aluminum raw material, and H ₂ O is used for oxidation of TMA, and the chamber temperature is It can be set to 120 to 170 ° C. Further, the pulse time of TMA can be 0.05 to 2 seconds, the purge time can be 1 to 10 seconds, the pulse time of H ₂ O can be 0.05 to 2 seconds, and the purge time can be 1 to 10 seconds. By repeating this cycle several tens to several hundreds of times, it is possible to obtain a sheet in which an aluminum oxide film having a thickness of 10 to 60 nm is laminated on both sides of the sheet.

<Thickness>
The thickness of the inorganic layer is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 20 nm or more, in order to exhibit stable moisture-proof performance. The thickness of the inorganic layer is preferably 1000 nm or less, more preferably 800 nm or less, and still more preferably 600 nm or less from the viewpoint of transparency and flexibility. In the inorganic layer of the composite sheet of the present invention, the thickness refers to the thickness of each inorganic layer unless a plurality of inorganic layers are provided, unless otherwise specified.

[Organic layer]
The composite sheet of the present invention may contain an organic layer in addition to the base sheet layer and the inorganic layer. The organic layer may be formed only on one side of the base sheet layer, or may be formed on both sides. Moreover, it may be formed in contact with the base sheet layer, and may be formed with another layer, for example, an inorganic layer, between the base sheet layer and the base sheet layer. The organic layer may be a single layer or may be stacked as a plurality of layers.

  In forming the organic layer, the base sheet layer may be subjected to a chemical modification treatment or a hydrophobization treatment, if necessary, and then laminated, for example, with a matrix resin. Since the substrate sheet layer of the present invention is subjected to a substituent elimination treatment and the like, yellowing at a high temperature is suppressed, and therefore heating during the formation of the organic layer usually promotes yellowing. A process or a UV irradiation process may be included, and various means can be taken.

<Matrix resin material>
The matrix resin is not particularly limited. Irradiated with a thermoplastic resin, a thermosetting resin (a cured product obtained by polymerizing and curing a precursor of a thermosetting resin by heating), or a photocurable resin (a precursor of a photocurable resin (such as ultraviolet light or electron beam)) And the like can be used. These may be 1 type and may be 2 or more types.

  The thermoplastic resin is not particularly limited. Examples thereof include styrene resins, acrylic resins, aromatic polycarbonate resins, aliphatic polycarbonate resins, aromatic polyester resins, aliphatic polyester resins, and aliphatic polyolefin resins. In addition, cyclic olefin resins, polyamide resins, polyphenylene ether resins, thermoplastic polyimide resins, polyacetal resins, polysulfone resins, non-crystalline fluorine resins and the like can be mentioned.

  Although it does not specifically limit as a thermosetting resin, An epoxy resin, an acrylic resin, oxetane resin, a phenol resin, a urea resin, a melamine resin etc. are mentioned. In addition, unsaturated polyester resin, silicone resin, polyurethane resin, silsesquioxane resin, diallyl phthalate resin and the like can be mentioned.

  Although it does not specifically limit as a photocurable resin, The epoxy resin, the acrylic resin, silsesquioxane resin, or oxetane resin etc. which were illustrated as the above-mentioned thermosetting resin are mentioned.

  Furthermore, as a specific example of a thermoplastic resin, a thermosetting resin, or a photocurable resin, the thing as described in Unexamined-Japanese-Patent No. 2009-299043 is mentioned.

The matrix resin is preferably a synthetic polymer which is amorphous and has a high glass transition temperature (Tg) in terms of obtaining a composite excellent in transparency and high in durability. The degree of amorphousness is preferably 10% or less in crystallinity, and more preferably 5% or less. Further, Tg preferably is 110 ° C. or more, particularly 120 ° C. or more, particularly 130 ° C. or more. If the Tg is low, for example, there is a risk of deformation when touching with hot water or the like, which causes a problem in practical use. The Tg of the matrix resin is determined by measurement by DSC method, and the degree of crystallinity can be calculated from the density of the amorphous part and the crystalline part.
Further, in order to obtain a low water absorption composite, the matrix resin preferably has a small amount of hydrophilic functional groups such as a hydroxy group, a carboxyl group, or an amino group.

  In one particularly preferred embodiment as a composite sheet in which organic layers are laminated, polysilsesquioxane obtained by crosslinking and curing a silsesquioxane resin is used as a matrix resin. As commercially available silsesquioxane resin which can be used for this embodiment, for example, OX-SQ TX-100, OX-SQ SI-20, OX-SQ ME-20, OX-SQ HDX, AC-SQ TA -100 are mentioned. In addition, MAC-SQ TM-100, AC-SQ SI-20, MAC-SQ SI-20, MAC-SQ HDM (above, Toagosei), and Compoceran SQ series (Arakawa Chemical Industries) can be mentioned. A thiol group containing silsesquioxane compound can be used for bridge | crosslinking of silsesquioxane resin. Examples of commercially available thiol group-containing silsesquioxane compounds that can be used in the present embodiment include Compoceran HBSQ series (Arakawa Chemical Industries).

  In another preferred embodiment, as a matrix resin, a urethane acrylate resin composition may be used which is rapidly cured three-dimensionally by radical polymerization by irradiation with an electron beam or ultraviolet light. As a commercially available urethane acrylate resin which can be used for this embodiment, beam set 575CB (Arakawa Chemical Industries) etc. are mentioned, for example. For crosslinking, methyl ethyl ketone can be used. The resin layer to be formed has good chemical resistance and surface curability, and is thus further laminated to the inorganic layer to be suitable as a composite sheet having a large surface hardness.

<Thickness>
The thickness of the organic layer is not particularly limited, but is preferably sufficient to impart moisture resistance to the base sheet layer and to such an extent that the advantage of low linear thermal expansion of the sheet is not impaired. For example, it may be about 0.1 to 50 μm, may be 0.1 to 30 μm, may be 0.2 to 20 μm, and may be 0.5 to 10 μm. In addition, regarding the organic layer of the composite sheet of the present invention, the thickness refers to the thickness of each organic layer, unless otherwise specified, in the case where a plurality of binding layers are provided.

<Method of laminating matrix resin>
There is no restriction | limiting in particular as a method to laminate | stack matrix resin, For example, the following method is mentioned.
(A) A method of alternately arranging a thermoplastic resin sheet and a base sheet layer and bringing them into close contact with a heating press or the like.
(B) One or more selected from a liquid thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor on one side or both sides of the inorganic sheet laminated on the substrate sheet or on the substrate sheet Method of applying and polymerization curing.
(C) A method of applying a resin solution to one side or both sides of an inorganic layer laminated on a substrate sheet or on a substrate sheet, removing a solvent, and optionally polymerizing and curing it. Here, the resin solution is a solution containing one or more solutes selected from a thermoplastic resin, a thermoplastic resin precursor, a thermosetting resin precursor, and a photocurable resin precursor.

As a method of (a), a film or sheet of a thermoplastic resin is disposed on one side or both sides of an inorganic layer laminated to a substrate sheet or to a substrate sheet, and heat or press is applied if desired. The method of bonding together a plastic resin and a base material sheet layer is mentioned. In this case, an adhesive, a primer, or the like may be applied to the surface of the base sheet layer and attached. A method of passing between two pressurized rolls or a method of pressing in a vacuum state can be used so that air bubbles are not held in bonding.

As a method of (b), there is a method of applying a thermosetting resin precursor formulated with a thermal polymerization initiator on one side or both sides of a substrate sheet layer and curing by heating to adhere both of them. . Moreover, the method of apply | coating and hardening radiation, such as an ultraviolet-ray, is apply | coated to the single side | surface or both surfaces of a base material sheet layer by apply | coating the photocurable resin precursor which prescribed the photoinitiator.
Moreover, after apply | coating a heat | fever or a photocurable resin precursor to a base material sheet layer, you may make it harden | cure, after making a multilayer structure, such as laminating | stacking a base material sheet layer further.

As the method (c), there is a method of preparing a resin solution in which a resin soluble in a solvent is dissolved, applying the solution on one side or both sides of a substrate sheet layer, and removing the solvent by heating. In the case of a photocurable resin, polymerization curing by radiation or the like is performed if desired.
The solvent for dissolving the resin may be selected according to the solubility of the resin.

[Curable composition]
In the above thermoplastic resin precursor, thermosetting resin precursor, and photocurable resin precursor, a chain transfer agent, an ultraviolet absorber, a filler other than cellulose, a silane coupling agent, etc. are appropriately blended. It may be a composition (hereinafter, referred to as "curable composition").

When the curable composition contains a chain transfer agent, the reaction can proceed uniformly. As a chain transfer agent, for example, a polyfunctional mercaptan compound having two or more thiol groups in the molecule can be used. By using a polyfunctional mercaptan compound, it is possible to provide the cured product with appropriate toughness.
The mercaptan compound is not particularly limited. For example, pentaerythritol tetrakis (β-thiopropionate), trimethylolpropane tris (β-thiopropionate), or tris [2- (β-thiopropionyloxyethoxy) ethyl] triisocyanurate and the like can be mentioned. It is preferable to use one or more of these.
When the curable composition contains a chain transfer agent, the chain transfer agent is usually contained in a proportion of 30% by mass or less based on the total of the radically polymerizable compounds in the curable composition.

When the curable composition contains a UV absorber, coloring can be prevented. The ultraviolet absorber is selected from, for example, benzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers, and the ultraviolet absorber may be used alone or in combination of two or more.
When the curable composition contains a UV absorber, the UV absorber is usually contained in a proportion of 0.01 to 1 part by mass with respect to 100 parts by mass of the total of the radically polymerizable compounds in the curable composition. .

  The filler is not particularly limited, and examples thereof include inorganic particles and organic polymers. Specifically, inorganic particles such as silica particles, titania particles, or alumina particles can be mentioned. Further, particles of a transparent cycloolefin polymer such as Zeonex (Nippon Zeon Co.) or Arton (JSR Co.), or particles of a general-purpose thermoplastic polymer such as polycarbonate or polymethyl methacrylate can be mentioned. Among them, use of nano-sized silica particles is preferable because transparency can be maintained. In addition, it is preferable to dissolve the polymer to a high concentration by using particles of a polymer similar in structure to the ultraviolet curable monomer as a filler.

The silane coupling agent is not particularly limited, and examples thereof include γ-((meth) acryloxypropyl) trimethoxysilane and γ-((meth) acryloxypropyl) methyldimethoxysilane. Further, γ-((meth) acryloxypropyl) methyldiethoxysilane γ-((meth) acryloxypropyl) triethoxysilane or γ- (acryloxypropyl) trimethoxysilane may, for example, be mentioned. These are preferable because they have a (meth) acrylic group in the molecule and can be copolymerized with other monomers.
When the curable composition contains a silane coupling agent, the amount of the silane coupling agent is usually 0.1 to 50% by mass, preferably 1 to 20% by mass, based on the total of the radically polymerizable compounds in the curable composition. It is contained so that it becomes mass%. If this compounding amount is too small, the effect of containing this may not be obtained sufficiently, and if too large, optical properties such as transparency of the cured product may be impaired.

[Curing method]
The curable composition can be polymerized and cured by a known curing method to give a cured product.
The curing method may, for example, be thermal curing or radiation curing, and preferably radiation curing. Examples of radiation include infrared rays, visible rays, ultraviolet rays, and electron beams, and preferably light having a wavelength of 1 to 1000 nm. The electromagnetic wave is more preferably an electromagnetic wave having a wavelength of about 200 nm to 450 nm, and still more preferably an ultraviolet ray having a wavelength of 300 to 400 nm.

  As a specific curing method of the curable composition, a method of adding a thermal polymerization initiator which generates radicals and acids by heating in advance to the curable composition, and heating and polymerizing (hereinafter referred to as “thermal polymerization” In some cases, a photopolymerization initiator that generates radicals or acids by radiation such as ultraviolet light is added to a curable composition in advance, and radiation (preferably light) is applied to polymerize (hereinafter referred to as “light” Polymerization), or a method in which both a thermal polymerization initiator and a photopolymerization initiator are added in advance, and polymerization is performed by a combination of heat and light.

When polymerization and curing are performed by irradiation, the amount of radiation to be irradiated is arbitrary as long as the photopolymerization initiator generates radicals. However, when the amount is extremely small, the polymerization is incomplete and the heat resistance or mechanical properties of the cured product are not sufficiently expressed. On the other hand, when the amount is extremely excessive, light degradation such as yellowing of the cured product occurs. . Therefore, depending on the composition of the monomer and the type and amount of the photopolymerization initiator, ultraviolet light of 300 to 450 nm, preferably in the range of 0.1 to 200 J / cm ² , more preferably in the range of 1 to ²⁰ J / cm ² Irradiate.
Furthermore, it is more preferable to divide the radiation two or more times and to irradiate it. That is, by irradiating about 1/20 to 1/3 of the total irradiation amount at the first time and irradiating the necessary remaining amount after the second time, a cured product with smaller birefringence can be obtained.
As a specific example of the lamp used for radiation irradiation, a metal halide lamp, a high pressure mercury lamp lamp, an ultraviolet LED lamp, an electrodeless mercury lamp, etc. can be mentioned.

  Photopolymerization and thermal polymerization may be conducted simultaneously to complete the polymerization curing promptly. In this case, curing is performed by heating the curable composition in the range of 30 to 300 ° C. simultaneously with the radiation irradiation. In addition, although a thermal polymerization initiator may be added to the curable composition in order to complete the polymerization, if added in a large amount, the birefringence of the cured product is increased and the hue is deteriorated. Therefore, it is preferable that it is 0.1-2 mass% with respect to the sum total of a curable monomer component, and, as for the addition amount of a thermal-polymerization initiator, it is more preferable that it is 0.3-1 mass%.

Examples of the thermal polymerization initiator used for thermal polymerization include hydroperoxide, dialkyl peroxide, peroxy ester, diacyl peroxide, peroxy carbonate, peroxy ketal, ketone peroxide and the like. Specifically, benzoyl peroxide, diisopropyl peroxycarbonate, t-butylperoxy (2-ethylhexanoate) dicumyl peroxide, di-t-butyl peroxide, t-butylperoxybenzoate, t-butylhydro Peroxide, diisopropylbenzene hydroperoxide, or 1,1,3,3-tetramethylbutyl hydroperoxide can be used. These polymerization initiators may be used alone or in combination of two or more.
When thermal polymerization is initiated at the time of light irradiation, it becomes difficult to control the polymerization, so the thermal polymerization initiator preferably has a one-minute half-life temperature of 120 ° C. or more and 300 ° C. or less.

  As a photopolymerization initiator used for photopolymerization, a photo radical generator or a photo cationic polymerization initiator is usually used. The photopolymerization initiator may be used alone or in combination of two or more.

  As the photoradical generator, known compounds known to be usable for this use can be used. For example, benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2,6-dimethylbenzoyl diphenyl phosphine oxide, or 2,4,6-trimethyl benzoyl diphenyl phosphine oxide etc. may be mentioned. . Among these, benzophenone or 2,4,6-trimethyl benzoyl diphenyl phosphine oxide is preferable.

  A photocationic polymerization initiator is a compound which starts cationic polymerization by irradiation of radiations, such as an ultraviolet-ray and an electron beam, and the following are mentioned.

  For example, as an aromatic sulfonium salt, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate, bis [4- (diphenylsulfone) Nio) phenyl] sulfide bishexafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfide tetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoro, diphenyl-4- (phenylthio) ) Phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenyls Phonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrafluoroborate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, bis [4- (di ( 4- (2-hydroxyethoxy) phenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonylio) phenyl] sulfide bishexafluoroantimo , Bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonylio) phenyl] sulfide tetrafluoroborate, or bis [4- (di (4 (4 (2-hydroxyethoxy)) phenylsulfonyl O) phenyl] sulfide tetrakis (pentafluorophenyl) borate, and the like.

  As aromatic iodonium salts, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate, bis (dodecylphenyl) iodonium hexafluoroantimonate, bis (dodecyl) Phenyl) iodonium tetrakis (pentafluorophenyl) borate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluorophosphate, 4-methylphenyl-4- (1-methylethyl) phenyliodonium hexafluoroantimonate, 4-Methylphenyl-4- (1-methylethyl) phenyliodonium hexafluoroborate Or 4-methylphenyl-4- (1-methylethyl) phenyl iodonium tetrakis (pentafluorophenyl) borate, and the like.

  As the aromatic diazonium salt, phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis (pentafluorophenyl) borate and the like can be mentioned.

  As an aromatic ammonium salt, 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2-cyano Cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, 1- (naphthylmethyl) -2- Examples include cyanopyridinium tetrafluoroborate, 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) borate and the like. As (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron salt, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron (II) Hexafluorophosphate, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron (II) hexafluoroantimonate, (2,4-cyclopentadien-1-yl) [(1-Methylethyl) benzene] -iron (II) tetrafluoroborate, (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron (II) tetrakis (pentafluorophenyl) Borate etc. are mentioned.

  As a commercial item of these photocationic polymerization initiators, for example, UVI6990 manufactured by Union Carbide, UVI6979, SP-150 manufactured by ADEKA, SP-170, or SP-172, Irgacure 261 manufactured by Ciba Geigy, or Irgacure 250, Rhodia's RHODORSIL PI 2074, JMF-2456, Sanshin Chemical Industry Co., Ltd. Sanaid SI-60L, SI-80L, SI-100L, SI-110L, SI-180L, SI-100L, etc. .

  Furthermore, in addition to the photocationic polymerization initiator, a curing agent for curing the cationically polymerizable monomer may be added. Examples of curing agents include compounds such as amine compounds and polyaminoamide compounds synthesized from amine compounds, tertiary amine compounds, imidazole compounds, hydrazide compounds, melamine compounds, acid anhydrides, phenol compounds, thermal latent cationic polymerization catalysts Or dicyanamide and derivatives thereof. These curing agents may be used alone or in combination of two or more. Among these, as a heat latent cationic polymerization catalyst, Adekaoptone CP-66 or CP-77 (manufactured by ADEKA Co., Ltd.), or SunAid SI-15, SI-20, SI-25, SI-40, SI -45, SI-47, SI-60, SI-80, SI-100, SI-100L, SI-110L, SI-145, SI-150, SI-160, or SI-180L (Shin Shin Chemical Industry Co., Ltd. And the like).

  Photosensitizers can also be added. Specific examples include pyrene, perylene, acridine orange, thioxanthone, 2-chlorothioxanthone and benzoflavin. Examples of commercially available photosensitizers include Adekaitomer SP-100 (manufactured by ADEKA Co., Ltd.).

The component amount of the photopolymerization initiator is preferably 0.001 parts by mass or more, and preferably 0.01 parts by mass or more, based on 100 parts by mass of the total of the polymerizable compounds in the curable composition. Is more preferable, and more preferably 0.05 parts by mass or more. Further, the component amount of the photopolymerization initiator is preferably 5 parts by mass or less, more preferably 2 parts by mass or less, and still more preferably 0.1 parts by mass or less.
That is, the range of the component amount of the photopolymerization initiator is preferably 0.001 to 5 parts by mass, and 0.01 to 2 parts by mass, based on 100 parts by mass of the total of the polymerizable compounds in the curable composition. A part is more preferable and 0.05-0.1 mass part is further more preferable.
However, when a photoinitiator is a photocationic polymerization initiator, it is 0.01 mass part or more with respect to 100 mass parts of total amounts of a cationically polymerizable monomer. The amount is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, usually 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 1 part by mass or less.
That is, when the photopolymerization initiator is a photocationic polymerization initiator, the range of the component amount of the photopolymerization initiator is 0.01 to 10 parts by mass with respect to 100 parts by mass of the total of the cationically polymerizable monomers Is preferred. Moreover, 0.1-5 mass parts is more preferable, and 0.5-1 mass part is further more preferable.
When the addition amount of the photopolymerization initiator is too large, the polymerization proceeds rapidly, which not only increases the birefringence of the obtained cured product but also deteriorates the hue. For example, when the concentration of the photopolymerization initiator is 5 parts by mass, absorption of the photopolymerization initiator causes an uncured part to be generated because light can not reach the side opposite to the irradiation of the ultraviolet light. In addition, it is colored yellow and the hue is significantly degraded. On the other hand, if the amount is too small, the polymerization may not proceed sufficiently even if ultraviolet irradiation is performed.

[Chemical modification treatment as a step before resin compounding]
When laminating an organic layer on a substrate sheet, in order to improve adhesiveness with resin, a chemical modification process can be performed to a substrate sheet layer before laminating a matrix resin.

  Chemical modification is to react a chemical modifier with a hydroxy group in cellulose to add a functional group including a structure which the chemical modifier had.

  The modification method is not particularly limited, but there is a method of reacting cellulose fibers with the following chemical modifiers. The reaction conditions are also not particularly limited, but if desired, a solvent, a catalyst, or the like may be used, or heating, pressure reduction, or the like may be performed.

  The type of chemical modifier is one or two selected from the group consisting of acids, acid anhydrides, alcohols, halogenating reagents, isocyanates, alkoxysilanes, alkoxysiloxanes, cyclic ethers such as silazane and oxirane (epoxy). The above substances can be mentioned.

Examples of the acid include acetic acid, acrylic acid, methacrylic acid, propanoic acid, butanoic acid, 2-butanoic acid, and pentanoic acid.
Examples of the acid anhydride include acetic anhydride, acrylic anhydride, methacrylic anhydride, propanoic acid anhydride, butanoic acid anhydride, 2-butanoic acid anhydride, or pentanoic acid anhydride.
Examples of the halogenation reagent include acetyl halide, acryloyl halide, methacroyl halide, propanoyl halide, butanoyl halide, 2-butanoyl halide, pentanoyl halide, benzoyl halide, naphthoyl halide and the like.
Examples of the alcohol include methanol, ethanol, propanol, 2-propanol and the like.
Examples of the isocyanate include methyl isocyanate, ethyl isocyanate, propyl isocyanate and the like.
As an alkoxysilane, a methoxysilane, an ethoxysilane, etc. are mentioned, for example.
Examples of alkoxysiloxanes include butoxypolydimethylsiloxane and the like.
Examples of silazane include hexamethyldisilazane, tetramethyldisilazane, diphenyltetramethyldisilazane and the like.
Examples of cyclic ethers such as oxirane (epoxy) include ethyl oxirane and ethyl oxetane.
Among these, in particular, acetic anhydride, acrylic anhydride, methacrylic anhydride, benzoyl halide, naphthoyl halide, methoxysilane or hexamethyldisilazane is preferable.
One of these chemical modifiers may be used alone, or two or more thereof may be used in combination.

  As the catalyst, it is preferable to use a basic catalyst such as pyridine, triethylamine, sodium hydroxide or sodium acetate, or an acidic catalyst such as acetic acid, sulfuric acid or perchloric acid.

  As temperature conditions in chemical modification, if it is too high, yellowing of cellulose and a decrease in the degree of polymerization may occur, and if it is too low, the reaction rate may decrease, so 10 to 250 ° C. is preferable. The reaction time depends on the chemical modifier and the chemical modification rate, but is usually several minutes to several tens of hours.

In the present invention, the chemical modification ratio of cellulose is usually 65 mol% or less, preferably 50 mol% or less, more preferably 40 mol% or less based on the total hydroxyl groups of cellulose. There is no particular lower limit of the chemical modification rate.
By performing chemical modification, the decomposition temperature of cellulose is increased and the heat resistance is increased. However, when the chemical modification rate is too high, the cellulose structure is broken and the crystallinity is reduced. The thermal expansion coefficient tends to be large, which is not preferable.

  The term "chemical modification rate" as used herein refers to the proportion of chemically modified ones of all the hydroxy groups in cellulose. The chemical modification ratio can be determined by IR, NMR, titration method or the like. For example, the chemical modification rate of cellulose ester by titration method can be determined according to the description in the above-mentioned Patent Document 4.

  When the base sheet layer is chemically modified, it is preferable that the chemical modification is followed by sufficient washing to terminate the reaction. Unreacted unreacted chemical modifiers are not preferable because they may cause coloration later or cause problems when they are complexed with a resin. Further, after sufficient washing, it is preferable to further substitute with an organic solvent such as alcohol. In this case, the base sheet layer can be easily substituted by immersing the base sheet layer in an organic solvent such as alcohol.

When the base sheet layer is chemically modified, the base sheet layer is usually dried after the chemical modification. This drying may be air drying, vacuum drying, pressure drying, or heat drying.
When heating during drying, the temperature is preferably 50 ° C. or more, more preferably 80 ° C. or more, and preferably 250 ° C. or less, more preferably 150 ° C. or less.
That is, 50-250 degreeC is preferable and, as for the range of the temperature in the case of heating at the time of drying, 80-150 degreeC is more preferable.
If the heating temperature is too low, drying may take time or drying may be insufficient. If the heating temperature is too high, the base sheet layer may be colored or decomposed.
Moreover, as for a pressure (gauge pressure), when pressurizing, 0.01 MPa or more is preferable, 0.1 MPa or more is more preferable, 5 MPa or less is preferable, and 1 MPa or less is more preferable.
That is, as for the range of the pressure (gauge pressure) in the case of pressurizing, 0.01-5 Mpa is preferable and 0.1-1 Mpa is more preferable.
Too low a pressure may result in insufficient drying, and too high a pressure may cause the base sheet layer to collapse or decompose.

[Composite sheet]
<Stacking>
The composite sheet constructed according to the present invention is formed on at least one side of a base sheet layer containing fine fibers into which a substituent having electrostatic and / or steric functionality is introduced, and a base sheet layer. Containing an inorganic layer. The composite sheet preferably includes at least one inorganic layer and at least one organic layer formed on at least one side of the base sheet layer. When laminating the inorganic layer and the organic layer, although the order is not particularly limited, laminating the organic layer on the surface of the base sheet first makes the surface for forming the inorganic layer smooth and the inorganic layer formed Is preferable in that it can be made less defective. In addition, other component layers other than the organic layer and the inorganic layer may be included, for example, an easily adhesive layer for facilitating adhesion of the upper layer.

  The number of layers such as the inorganic layer and the organic layer is not particularly limited. From the viewpoint of sufficient moisture resistance while maintaining flexibility and transparency, it is preferable to alternately stack, for example, 2 layers of inorganic layers and 2 layers of organic layers on one side, for example, 3 layers to 7 Layer lamination is more preferable.

<Specially Preferred Properties>
The composite sheet obtained according to the present invention may have properties such as total light transmittance, haze, yellowness, linear thermal expansion coefficient, and water vapor transmittance, which are desirable properties as an optical material. The measuring method and preferable range of these characteristics are demonstrated below.

[Total light transmittance]
In the present invention, the term "total light transmittance (%)" refers to a value measured by C light using a haze meter in accordance with JIS K7105 unless otherwise specified.

  According to the configuration of the present invention, the total light transmittance can be 80% or more in a composite sheet having flexibility, a low linear thermal expansion coefficient, and moisture resistance. In a preferred embodiment, it can be 82% or more, and in a more preferred embodiment, it can be 90% or more.

[Haze]
In the present invention, the term “haze value” refers to a value measured by C light using a haze meter in accordance with JIS K7136 unless otherwise specified. Haze is an index relating to the transparency of a sheet and represents turbidity (cloudiness). It is determined from the ratio of diffuse transmission light to total light transmission light, and can also be affected by the surface roughness.

  By setting it as the composite sheet of the structure of this invention, in the composite sheet which has flexibility, a low linear thermal expansion coefficient, and also moisture resistance was provided, a haze value can be 2 or less. In a preferred embodiment, it may be 1.2 or less, and in a more preferred embodiment, it may be 1.0 or less.

Yellowness
In the context of the present invention, yellowness, unless otherwise stated, refers to the value determined by the sheet under the ASTM standard and the E313 yellow index (YI) by means of a suitable spectrophotometer (Spectro Eye), unless otherwise stated. . Yellowness can be measured before and after heating at 200 ° C. for 4 hours under vacuum and can be judged by their difference.

  By setting it as the composite sheet of the structure of this invention, the yellowness degree (YI) after a heating can be made 23 or less. In a preferred embodiment, it may be 12 or less, and in a more preferred embodiment, it may be 8 or less. Moreover, the change ((DELTA) YI) of the degree of yellowness before and behind a heating can be made 17 or less by setting it as the composite sheet of the structure of this invention. In a preferred embodiment, it may be 5 or less, and in a more preferred embodiment, it may be 3 or less.

[Linear thermal expansion coefficient]
In the present invention, the term "linear thermal expansion coefficient" refers to a value obtained as follows, unless otherwise specified. The target sheet is cut into 3 mm wide × 30 mm long by a laser cutter. The temperature is changed from room temperature to 180 ° C. at 5 ° C./min. Temperature from 180 ° C. to 25 ° C. at 5 ° C./min. Temperature from 25 ° C. to 180 ° C. at 5 ° C./min. To raise the temperature. The linear thermal expansion coefficient is determined from the measured values at 60 ° C. to 100 ° C. when the temperature is raised to the second time.

  By setting it as the composite sheet of the structure of this invention, a linear thermal expansion coefficient can be 18 or less. In a preferred embodiment, it may be 15 or less, and in a more preferred embodiment, it may be 10 or less.

[Humidity expansion coefficient]
In the present invention, the term "humidity expansion coefficient" refers to a value determined under the conditions described in the Examples section of the present specification using an appropriate humidity expansion and contraction measuring device, unless otherwise specified.

  By setting it as the composite sheet of the structure of this invention, a moisture expansion coefficient can be 50 or less in the composite sheet which has high transparency, flexibility, and a low linear thermal expansion coefficient. In a preferred embodiment, it may be 40 or less, and in a more preferred embodiment, it may be 20 or less.

[Water vapor permeability]
In the present invention, when the water vapor transmission rate (g / m ² · day) is referred to, the temperature is 40 ° C., 90% using an appropriate water vapor transmission rate measuring device according to JIS standard K7129 except when specifically described. The value when measured under the atmosphere of RH.

By setting it as the composite sheet of the structure of this invention, water vapor transmission rate can be 800 g / m < ² > * day or less in the composite sheet which has high transparency, flexibility, and a low linear thermal expansion coefficient. In a preferred embodiment, it may be 400 g / m ² · day or less, and in a more preferred embodiment, it may be 200 g / m ² · day or less.

[Others]
By setting it as the composite sheet of the structure of this invention, the sheet | seat excellent also in surface roughness, surface hardness, a bending test (mandrel method), etc. can be obtained. These test methods are well known to those skilled in the art.

[Use of composite sheet]
In the embodiment of the present invention, it is possible to obtain a composite sheet in which yellowing is suppressed and moisture resistance is improved while taking advantage of the characteristics of the fine fiber-containing sheet having transparency, high elastic modulus, and low latent thermal expansion coefficient. Such a composite sheet is suitable for use as a display element, a lighting element, a solar cell or a window material, or a panel or a substrate for these, since it has excellent optical properties.

  More specifically, the composite sheet is suitable for use as a flexible display, a touch panel, a liquid crystal display, a plasma display, an organic EL display, a field emission display, a display such as a rear projection television, or an LED element. In addition, the composite sheet is suitable for use as a solar cell substrate such as a silicon-based solar cell or a dye-sensitized solar cell. In applications as a substrate, it may be laminated with a barrier film, ITO, TFT or the like. In addition, it is suitable for use as a window material for automobiles, railway vehicles, aircraft, houses, office buildings, factories and the like. As the window material, if necessary, a film such as a fluorine film or a hard coat film or a material having impact resistance and light resistance may be laminated.

  The composite sheet can also be used as a structural material other than transparent material applications, taking advantage of properties such as low coefficient of linear expansion, high elasticity, high strength, and light weight. In particular, suitable as glazing, interior materials, outer plates, bumpers, automobiles, railway vehicles, aircraft materials, PC cases, home appliance parts, packaging materials, construction materials, civil engineering materials, marine materials, other industrial materials, etc. It can be used for

  The composite sheet provided in the embodiments of the present invention can be used for various products. Examples of the product include a computer using the above-described display element or display, a tablet terminal, a mobile phone, a light bulb using the light element, a light (lighting fixtures / lighting device), an induction light, a backlight for liquid crystal panel, a flashlight Lights, headlights for bicycles, car interior lights and meters, traffic lights, height lights inside and outside the building, home lights, school lights, medical lights, plant lights, plant growing lights, video lighting lights Lighting in a 24-hour or late-night store such as a convenience store, lighting in a cold storage / freezer; houses, buildings, cars, railway cars, aircraft, home appliances, etc. using window materials and structural materials be able to.

  Hereinafter, the present invention will be described by way of examples, but the scope of the present invention is not limited by the examples.

Example 1
<Preparation of phosphate group introduced cellulose fiber>
Impregnate unrefined softwood kraft pulp (manufactured by Oji Holdings) at 1000 g with absolutely dry mass, impregnate a chemical solution consisting of urea, sodium phosphate (molar ratio of phosphorus atom to sodium atom Na / P = 1.45), water, and squeeze The excess chemical solution was squeezed off to obtain a chemical solution impregnated pulp. The chemical solution-impregnated pulp contained 1000 g of pulp, 950 g of urea, 400 g of sodium phosphate as phosphorus atom, and 1200 g of water as bone dry mass. The chemical-impregnated pulp was dried and heated in an oven heated to 150 ° C. to introduce phosphoric acid groups into the pulp. After pouring 25 L of ion-exchanged water into the drug solution impregnated pulp which has been subjected to the drying and heating steps, stirring and uniformly dispersing, the step of dewatering by filtration and obtaining a dewatered sheet was repeated twice. Next, the obtained dewatered sheet was diluted with 25 L of ion exchanged water, and 1N aqueous sodium hydroxide solution was added little by little while stirring to obtain a pulp slurry having a pH of 11 to 13. Thereafter, the pulp slurry is dewatered to obtain a dewatered sheet, and then 25 L of ion-exchanged water is poured again, and after stirring and uniformly dispersing, the step of dewatering by filtration and obtaining the dewatered sheet is repeated twice. A phosphate-modified cellulose fiber was obtained.

<Machine processing>
Ion-exchanged water was added to the pulp obtained after washing and dewatering to make a 1.0 mass% pulp suspension. This pulp suspension was passed 5 times at an operating pressure of 1200 bar with a high pressure homogenizer (manufactured by NiroSoavi: Panda Plus 2000) to obtain a fine fibrous cellulose suspension. Furthermore, it passed 5 times at a pressure of 245 MPa with a wet atomization device (manufactured by Sugino Machine Co., Ltd .: Altimizer) to obtain a fine fibrous cellulose suspension (1). The average fiber width of the fine fibrous cellulose was 4.2 nm.

<Change in degree of neutralization>
A 1/10 strongly acidic ion exchange resin (manufactured by Organo Corporation: Amberjet 1024) by volume was added to the fine fibrous cellulose suspension (1) obtained by mechanical treatment, and shaking was performed for 1 hour. Then, it poured on the mesh of 90 micrometers of openings, and the resin and the slurry were isolate | separated, and the fine fibrous cellulose suspension (2) was obtained. The fine fibrous cellulose suspension (1) and the fine fibrous cellulose suspension (2) were mixed at a volume ratio of 50:50 to obtain a fine fibrous cellulose suspension (3).

<Sheet form>
Polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd .: molecular weight 4,000,000) was added to the fine fibrous cellulose suspension (3) to 15 parts by mass with respect to 100 parts by mass of the fine fibrous cellulose. In addition, concentration adjustment was performed so that solid content concentration might be 0.5 mass%. The suspension was weighed so that the finished basis weight of the sheet was 37.5 g / m ² , spread on a commercially available acrylic plate, and dried in an oven at 50 ° C. In addition, a plate for blocking was arranged on the acrylic plate so as to obtain a predetermined basis weight, and the obtained sheet was made to be a square. A sheet was obtained by the above procedure. The thickness of the obtained sheet was 25 μm, and the density was 1.49 g / cm ³ .

<Substituent desorption process>
A 15 cm square hole was placed on a heat-resistant rubber sheet (manufactured by Shin-Etsu Chemical Co., Ltd .: X-30-4084-U) as a spacer on a stainless steel plate, and 50 mL of glycerin was developed into the hole. A sheet cut out in a size of 12 cm was dipped therein, a stainless steel plate was stacked thereon, and the sheet was installed in a heat press (manual hydraulic vacuum heating press manufactured by Imoto Machinery Co., Ltd.) heated to 180 ° C. As a substituent removal treatment, the sheet was treated at 180 ° C. for 30 minutes, and then the sheet was immersed in 150 mL of methanol and washed. The washing was repeated three times, and the sheet was attached to glass and dried by heating at 100 ° C. for 5 minutes to obtain a sheet.

<Aluminum oxide film formation processing>
The sheet subjected to the substituent elimination treatment was subjected to aluminum oxide film formation with SUNALE R-100B (manufactured by Picosun). Trimethylaluminum (TMA) was used as an aluminum raw material, and H ₂ O was used for oxidation of TMA. The chamber temperature was set to 150 ° C., the TMA pulse time was 0.1 second, the purge time was 4 seconds, the H ₂ O pulse time was 0.1 second, and the purge time was 4 seconds. By repeating this cycle for 405 cycles, a sheet in which an aluminum oxide film having a film thickness of 30 nm was laminated on both sides of the sheet was obtained.

Example 2
The resin layer was laminated | stacked on both surfaces of the substituent detachment sheet | seat obtained by carrying out similarly to Example 1 in the following procedures. 10 parts by weight of a silsesquioxane resin ("Compoceran SQ 107" manufactured by Arakawa Chemical Industries, Ltd.), 30 parts by weight of a curing agent ("HBSQ 202" manufactured by Arakawa Chemical Industries, Ltd.), 60 parts by weight of isopropyl alcohol Obtained. Next, the coating liquid was applied to one side of the substrate with a mayer bar. Then, after drying for 3 minutes at 100 ° C., ultraviolet light of 300 mJ / cm ² is irradiated using a UV conveyor device (“ECS-4011 GX” manufactured by Eye Graphics Co., Ltd.) to cure the coating liquid, and the thickness is 5 μm. The resin layer of Furthermore, a resin layer having a thickness of 5 μm was formed on the opposite surface in the same manner. Furthermore, in the same manner as in Example 1, an aluminum oxide film was formed on the obtained resin laminate sheet. By the above procedure, a sheet in which an aluminum oxide film was laminated on both sides on which the resin layer was deposited was obtained.

[Example 3]
On the resin laminated sheet obtained in Example 2, a silicon oxynitride film was formed by using an ICP-CVD roll-to-roll apparatus (manufactured by Celback Co., Ltd.). The resin laminated sheet was bonded to the upper surface of the carrier film (PET film) with a double-sided tape and placed in a vacuum chamber. The temperature in the vacuum chamber was set to 50 ° C., and the inflowing gases were silane, ammonia, oxygen and nitrogen. Plasma discharge was generated and film formation was performed for 45 minutes, to obtain a sheet in which a silicon oxynitride film having a film thickness of 500 nm was laminated on one side of a resin laminated sheet. Furthermore, a film was formed on the opposite side by the same procedure to obtain a sheet in which a silicon oxynitride film having a thickness of 500 nm was laminated on both sides of the sheet.

Example 4
A resin layer was laminated on the both sides of the aluminum oxide film laminated sheet obtained in Example 3 in the following procedure. A curable resin precursor solution was obtained by mixing 50 parts by weight of a urethane acrylate resin composition ("Beamset 575CB" manufactured by Arakawa Chemical Industries, Ltd.) and 50 parts by weight of methyl ethyl ketone. The curable resin precursor solution described above was coated on a sheet using a mayer bar. Next, after drying at 80 ° C. for 3 minutes, 300 mJ / cm 2 of ultraviolet light is irradiated using a UV conveyor device (“ECS-4011 GX” manufactured by Eye Graphics Co., Ltd.) to cure the curable resin precursor solution, and the thickness is A 5 μm resin layer was formed. Furthermore, a resin layer having a thickness of 5 μm was formed on the opposite surface in the same manner. By the above procedure, a sheet in which the resin layer was laminated on both sides of the laminated aluminum oxide film was obtained.

[Example 5]
Hardwood kraft pulp (LBKP) was dried at 105 ° C. for 3 hours to obtain a dry pulp having a water content of 3% by mass or less. Then, 4 g of dried pulp and 4 g of maleic anhydride (100 parts by mass with respect to 100 parts by mass of dried pulp) were charged in an autoclave and treated at 150 ° C. for 2 hours. Next, the maleic anhydride-treated pulp was washed three times with 500 mL of water, and then ion-exchanged water was added to prepare a 490 mL slurry. Then, while stirring the slurry, 10 mL of 4 N aqueous sodium hydroxide solution was added little by little to make the pH of the slurry 12-13, and the pulp was alkali-treated. Thereafter, the pulp after alkali treatment was washed with water until the pH became 8 or less. Ion-exchanged water was added to the pulp obtained after washing and dewatering to make a 1.0 mass% pulp suspension. This pulp suspension was passed 5 times at an operating pressure of 1200 bar with a high pressure homogenizer (manufactured by NiroSoavi: Panda Plus 2000) to obtain a fine fibrous cellulose suspension. Furthermore, it passed 5 times at a pressure of 245 MPa with a wet atomization device (manufactured by Sugino Machine Co., Ltd .: Altimizer) to obtain a fine fibrous cellulose suspension (4). The average fiber width of the fine fibrous cellulose was 4.5 nm.
A sheet was produced in the same manner as in Example 1 using the fine fibrous cellulose suspension (4) as a raw material, and then a substituent removal treatment was performed to obtain a sheet. An aluminum oxide film and a resin layer were laminated in the same manner as in Example 2 for the obtained sheet, and a sheet in which the resin layer was laminated on both sides of the laminated aluminum oxide film was obtained.

Comparative Example 1
A sheet was obtained in the same manner as in Example 1 except that the aluminum oxide film forming process was not performed.

Comparative Example 2
A sheet was obtained in the same manner as in Example 5 except that the aluminum oxide film formation treatment and the resin layer deposition were not performed.

[Evaluation]
<Method>
The sheets produced in Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated according to the following evaluation method.

(1) Total Light Transmittance The total light transmittance of C light was measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS K7105.

(2) Haze Based on JIS standard K7136, the haze value by C light was measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd.).

(3) Yellowness The obtained sheet was heated at 200 ° C. under vacuum for 4 hours, and then the E313 yellow index was measured using a handy spectrophotometer (Spectro Eye) manufactured by Gretag Macbeth in accordance with ASTM standards.

(4) Amount of Phosphoric Acid Group and Amount of Carboxyl Group The phosphorus and sodium atom concentrations in the sheet were measured by fluorescent X-ray analysis. That is, when the sheet is irradiated with X-rays, the characteristic X-rays of the phosphorus or sodium atoms released when the electrons of the outer shell transition to the holes generated by exciting the inner-shell electrons of the phosphorus or sodium atoms By measuring the intensity, the concentration of phosphorus or sodium atom was obtained. The measurement conditions are as follows.

・ Analyzer: X-ray fluorescence analyzer (XRF) PW-2404 manufactured by Spectris Co.
Measurement sample: Circular sample 27 mm in diameter X-ray tube: Rh tube Anticathode: Rhodium Spectroscopic crystal: Ge111 (phosphorus), PX1 (sodium)
・ Excitation light energy: 32kV-125mA
· Measurement line: phosphorus P-Kα1, sodium Na-Kα1
・ 2θ angle peak: 141.112 (phosphorus), 28.020 (sodium)
・ Measurement time: 54 seconds (phosphorus), 50 seconds (sodium)

  The functional group introduction amount was calculated from a calibration curve prepared by the following method. After preparing a sheet with a known amount of phosphate group and performing fluorescent X-ray analysis, a calibration curve of characteristic X-ray intensity of P atom and the amount of introduced phosphate group was created (FIG. 1). Similarly, for the carboxyl group, a sheet having a known carboxyl group and a Na salt type was prepared, and a calibration curve of characteristic X-ray intensity of the Na atom and the amount of introduced carboxyl group was prepared (FIG. 2).

(5) Linear thermal expansion coefficient The obtained sheet was cut into 3 mm wide × 30 mm long by a laser cutter. This was subjected to a chucking interval of 20 mm, a load of 10 g, in a nitrogen atmosphere, from room temperature to 180 ° C. at 5 ° C./min. Temperature from 180 ° C to 25 ° C at 5 ° C
/ Min. Temperature from 25 ° C. to 180 ° C. at 5 ° C./min. The linear thermal expansion coefficient was determined from the measured values at 60 ° C. to 100 ° C. at the second temperature rise when the temperature was raised.

(6) Humidity expansion coefficient Humidity expansion and contraction test was conducted under the following measurement conditions using a humidity expansion and contraction measuring device manufactured by Sagawa Works.

Test specimen: 15 mm × 90 mm N = 3
-Chuck distance: 50 mm
Weight: 10g
Temperature: 23 degrees Humidity: 30% RH 3 hours → 60% RH 3 hours Humidity stretch ratio (ppm /% RH) = (stretch ratio (60% RH) -stretch ratio (30% RH)) /
(60% RH-30% RH) x 10 ⁶
Stretching ratio (% RH) = ((L (30) -L (0)) / L (0) × 100)
L (0): The length of the test piece when a predetermined load is applied at a relative humidity of 50%.
L (30): The length of the test piece when a predetermined load is applied at a relative humidity of 30%.
L (60): The length of the test piece when a predetermined load is applied at a relative humidity of 60%.

(7) Water Vapor Permeability Measured under an atmosphere of temperature 40 ° C. and 90% RH using a water vapor permeability measuring device (manufactured by MOCON: PERMATRAN W / 33) according to JIS Standard K7129.

(8) Surface Roughness The obtained sheet was performed using a scanning probe microscope (Nanoscope IV and Nanoscope IIIa manufactured by Veeco) in accordance with ASME B46.12. Images were captured using a Si single crystal probe as a probe, a measurement mode of Tapping mode, and a measurement area of 10 μm × 10 μm. The obtained image is subjected to one Flatten processing (0th order) and one Planefit processing (XY) once as image processing for removing waviness using analysis software attached to a scanning probe microscope. The surface roughness was calculated.

(9) Surface Hardness The obtained sheet was evaluated for surface hardness by pencil hardness in accordance with JIS K 5600 5-4 scratch hardness (pencil method).
(10) Measurement of thickness of each layer
The thickness of the organic layer of 1 μm or more was measured before and after resin coating using Millitron 1202 d manufactured by Mahr. The film thickness of the inorganic layer of 1 μm or less was measured by a film thickness measuring apparatus F70 manufactured by Filmetrics. After forming the film on the silicon wafer under the same conditions as the film forming conditions of the aluminum oxide or silicon oxynitride film, each value measured in F70 is indirectly made the film thickness of the inorganic layer formed on the CNF sheet .

<Result>
The results are shown in Table 1.

Claims (22)

A composite comprising a base sheet layer containing fine fibers into which a substituent having electrostatic and / or steric functionality is introduced, and an inorganic layer formed on at least one side of the base sheet layer a seat, have a 2 or less haze value, the substituent is a group derived from phosphoric acid, a group derived from a carboxylic acid, a group derived from sulfuric acid, a group derived from sulfonic acid, alkyl group having 10 or more carbon atoms, And a composite sheet which is at least one selected from an amine-derived group . The composite sheet according to claim 1, further comprising an organic layer formed on at least one side of the base sheet layer. The composite sheet according to claim 2, wherein the thickness of the organic layer is 0.5 to 10 μm. The composite sheet according to any one of claims 1 to 3 , wherein the fine fibers are cellulose fine fibers having an average fiber width of 2 to 1000 nm. The substituent is at least one selected from the group consisting of a group derived from phosphoric acid, a group derived from carboxylic acid, and a group derived from sulfuric acid, and the substituent introduction amount is 0.01 to 2.0 mmol / g, The composite sheet according to any one of claims 1 to 4 . The composite sheet according to any one of claims 1 to 5 , wherein a substituent introduction amount in the sheet is 0.01 to 0.1 mmol / g. The composite sheet according to any one of claims 1 to 6 , wherein the thickness of the base sheet layer is 0.1 to 1200 μm. The inorganic layer comprises at least one selected from the group consisting of silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxycarbide, aluminum oxide, aluminum nitride, aluminum oxycarbide and aluminum oxynitride. The composite sheet according to any one of Items 1 to 7 . The composite sheet according to claim 2 , wherein the organic layer contains a thermosetting resin or a photocurable resin. Base sheet layer:
(A) obtaining a substituent-introduced fiber into the fiber raw material and (b) mechanically treating the substituent-introduced fiber obtained in step (a) to obtain a substituent-introduced fine fiber and (c) a step (c) manufactured by a manufacturing method having a step of preparing a sheet from the substituent-introduced fine fiber obtained in b) and a step of removing at least a part of the introduced substituent from the sheet obtained in step (d) (d) The composite sheet according to any one of claims 1 to 9 . The substituent having electrostatic and / or steric functionality is a group derived from phosphoric acid, and after step (a) and before step (c), further (e) a substituent-introduced fiber 11. The composite sheet according to claim 10 , which is produced by a production method having a step of changing the degree of neutralization of the substituent-introduced fibrils. The E313 yellow index (YI) change measured before and after heating at 200 ° C. for 4 hours under vacuum is 5 or less, and the thickness of the base sheet layer is 10 μm or more. Or the composite sheet described in 1 above. A composite sheet of 3 mm in width × 30 mm in length is placed between chucks of 20 mm and a load of 10 g under a nitrogen atmosphere from room temperature to 180 ° C. at 5 ° C./min. Temperature from 180 ° C. to 25 ° C. at 5 ° C./min. Temperature from 25 ° C. to 180 ° C. at 5 ° C./min. The composite sheet according to any one of claims 1 to 12, wherein the linear thermal expansion coefficient obtained from the measured values at 60 ° C to 100 ° C when the temperature is raised by the second temperature raising at the second time is 18 or less. . The composite sheet according to any one of claims 1 to 13, wherein the humidity expansion coefficient is 50 or less.
However, when the humidity expansion coefficient is changed from 30% RH 3 hours to 60% RH 3 hours with a composite sheet of 15 mm width x 90 mm length at a chuck interval of 50 mm, a load of 10 g, and a temperature of 23 degrees, the following equation Is the value obtained by
Humidity stretch ratio (ppm /% RH) = (stretch ratio (60% RH)-stretch ratio (30% RH)) /
(60% RH-30% RH) × 10 ⁶
Scaling factor (% RH) = ((L (30) -L (0)) / L (0) × 100)
L (0): The length of the test piece when a predetermined load is applied at a relative humidity of 50%.
L (30): The length of the test piece when a predetermined load is applied at a relative humidity of 30%.
L (60): The length of the test piece when a predetermined load is applied at a relative humidity of 60%. On at least one side of the substrate sheet layer,
The composite according to any one of claims 1 to 14 , wherein an inorganic layer and an organic layer laminated to the inorganic layer are formed, or an organic layer and an inorganic layer laminated to the organic layer are formed. Sheet. A flexible display using the composite sheet according to claim 15 . A solar cell using the composite sheet according to claim 15 . A lighting element using the composite sheet according to claim 15 . A display device using the composite sheet according to claim 15 . A touch panel using the composite sheet according to claim 15 . A window material using the composite sheet according to claim 15 . A structural material using the composite sheet according to claim 15 .

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