JP6641912B2 - Laminate and method of manufacturing laminate - Google Patents

Description

  The present invention relates to a laminate and a method for producing the laminate. Specifically, the present invention relates to a laminate having a fiber layer containing fine fibrous cellulose, an adhesive layer containing a specific functional group, and a resin layer containing a polymer of an acrylic monomer.

  2. Description of the Related Art In recent years, attention has been paid to materials that use reproducible natural fibers due to the substitution of petroleum resources and increasing environmental awareness. Among natural fibers, fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, particularly fibrous cellulose (pulp) derived from wood, has been widely used mainly as a paper product.

  Fine fibrous cellulose having a fiber diameter of 1 μm or less is also known as fibrous cellulose. Further, sheets composed of such fine fibrous cellulose and composite sheets including a fine fibrous cellulose-containing sheet and a resin layer have been developed. It is known that, in a sheet or a composite sheet containing fine fibrous cellulose, the number of contact points between fibers is significantly increased, so that tensile strength and the like are greatly improved. It is also known that when the fiber width is shorter than the wavelength of visible light, the transparency is greatly improved.

  Examples of the composite sheet include a sheet obtained by dispersing and curing fine fibrous cellulose in a resin composition containing an acrylic monomer and the like (for example, Patent Documents 1 and 2), and a porous fine fibrous cellulose. Sheets obtained by impregnating a containing sheet with a resin composition containing an acrylic monomer or the like (for example, Patent Documents 3 and 4) are known.

  As a composite sheet including a fine fibrous cellulose-containing sheet and a resin layer, a laminate in which a high-density nonporous fine fibrous cellulose-containing sheet and a resin layer are laminated via an adhesive layer is known (for example, , Patent Documents 5-7). Patent Documents 5 and 6 disclose a resin layer (base material) mainly composed of a polyester resin or the like, an adhesive layer containing a polyester resin or the like having a carboxyl group, and a fine fibrous cell made of fine fibrous cellulose having a carboxyl group. A laminate in which cellulose-containing sheets are laminated is disclosed. Here, a treatment such as a corona treatment is applied to the surface of the resin layer in order to enhance the adhesiveness of the resin layer. Patent Document 7 discloses a laminate in which an acrylic resin layer, an adhesive layer containing a polyester resin, and a fine fibrous cellulose-containing sheet having a phosphate group are laminated.

JP 2012-167202 A JP 2012-252038 A JP 2006-316253 A JP 2008-106152 A JP 2014-079938 A International Publication WO2012 / 070441 International Publication WO2015 / 163281

As described above, various aspects of composite sheets have been developed. However, in the composite sheets of Patent Documents 1 and 2, fine fibrous cellulose may aggregate in the resin composition, and in this case, there is a concern that the strength of the composite sheet is reduced. In addition, in order to prevent aggregation of the fine fibrous cellulose, a technique of dispersing the hydrophobic fine fibrous cellulose in the resin composition is also being studied, but in this case, the reinforcement derived from hydrogen bonding of the fine fibrous cellulose is considered. There was a problem that the effect could not be obtained.
On the other hand, in the composite sheets of Patent Literatures 3 and 4, there is a problem that the density of the fine fibrous cellulose decreases due to the porosity of the fine fibrous cellulose, and the strength of the composite sheet cannot be sufficiently obtained.

  As described in Patent Documents 5 and 6, it has been studied to obtain a laminate having excellent durability and the like by laminating a resin layer and a fine fibrous cellulose-containing sheet. There was a problem that the strength and the adhesion between the layers were not sufficient. Further, in the laminate of Patent Document 7, although the adhesion between the layers is improved, there is room for further improvement in the adhesion between the layers when placed under severe conditions of high temperature and high humidity. It became clear by the examination of those.

  In order to solve the problems of the related art, the present inventors have developed a laminate having high transparency and sufficient strength, and have excellent interlayer adhesion even in a severe environment. The study was conducted for the purpose of providing a laminate capable of exhibiting the above.

As a result of intensive studies to solve the above problems, the present inventors have found that a fiber layer containing fine fibrous cellulose and a laminate containing a resin layer containing a polymer of an acrylic monomer, a fiber layer and a resin It has been found that, by laminating the layers via an adhesive layer containing a specific functional group, excellent interlayer adhesion can be exhibited even in a severe environment. The present inventors have found that such a laminate, in addition to having high transparency and sufficient strength, can exhibit excellent interlayer adhesion under a severe environment, and completed the present invention. Reached.
Specifically, the present invention has the following configuration.

[1] A fiber layer, an adhesive layer, and a resin layer are provided in this order, the fiber layer includes fine fibrous cellulose having a fiber width of 1000 nm or less, and the adhesive layer is covalently bonded to a (meth) acryloyl group. And the resin layer further comprises at least one selected from a functional group (B) forming a covalent bond with a hydroxyl group and a hydrolyzable group of the functional group (B). A laminate comprising a polymer of the formula:
[2] The functional group (A) according to [1], wherein the functional group (A) is at least one selected from a group represented by (meth) acryloyl group and H ₂ C ＝ CR ² —CH (—OH) —. (Where R ² represents a hydrogen atom or a methyl group).
[3] The laminate according to [1] or [2], wherein the functional group (B) is at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an alkoxysilyl group, a silanol group, and an oxazoline group.
[4] The laminate according to any one of [1] to [3], wherein the adhesive layer includes a polymer having a functional group (A) and a compound having a functional group (B).
[5] After the laminate was placed under the conditions of a temperature of 85 ° C. and a relative humidity of 85% for 240 hours, the number of peelings in 100 fiber masses of the fiber layer 100 when performing a cross cut test in accordance with JIS K 5400 was 10 or less. The laminate according to any one of [1] to [4].
[6] The laminate according to any one of [1] to [5], wherein the density of the fiber layer is 1.0 g / cm ³ or more.
[7] The laminate according to any one of [1] to [6], which has a tensile modulus of 5 GPa or more.
[8] The laminate according to any one of [1] to [7], having a total light transmittance of 85% or more.
[9] The laminate according to any one of [1] to [8], wherein the adhesive layer further includes a polymerization initiator.
[10] The laminate according to any one of [1] to [9], wherein the resin layer further includes a polymerization initiator.
[11] The laminate according to any one of [1] to [10], wherein the adhesive layer is a coating adhesive layer, and the resin layer is a coating resin layer.
[12] An adhesive layer is formed by applying a composition containing a resin having a functional group (A) and a hydroxyl group and a compound having at least two functional groups (B) on at least one surface of the fiber layer. The laminate according to any one of [1] to [11], which is manufactured by applying a resin composition containing an acrylic monomer onto the adhesive layer to form a resin layer.
[13] A step of obtaining a fibrous layer containing fine fibrous cellulose having a fiber width of 1000 nm or less, and a functional group (A) forming a covalent bond with a (meth) acryloyl group and a hydroxyl group on at least one surface of the fibrous layer. Having a step of applying a composition containing a functional group (B) that forms a covalent bond with the resin, and forming an adhesive layer; and a step of applying a resin composition containing an acrylic monomer to form a resin layer. Manufacturing method.
[14] The functional group (A) is described in [13], which is at least one selected from a (meth) acryloyl group and a group represented by H ₂ C ＝ CR ² —CH (—OH) —. (Wherein R ² represents a hydrogen atom or a methyl group).
[15] The laminate according to [13] or [14], wherein the functional group (B) is at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an alkoxysilyl group, a silanol group, and an oxazoline group. Production method.
[16] The composition containing a functional group (A) and a functional group (B) contains a resin having a functional group (A) and a hydroxyl group, and a compound having at least two functional groups (B) [13] to The method for producing a laminate according to any one of [15].
[17] The method for producing a laminate according to any one of [13] to [16], wherein the composition containing the functional group (A) and the functional group (B) further includes a polymerization initiator.
[18] The method for producing a laminate according to any one of [13] to [17], wherein the resin composition further includes a polymerization initiator.

  ADVANTAGE OF THE INVENTION According to this invention, it is a laminated body which has high transparency and sufficient intensity | strength, and can obtain the laminated body which can exhibit the excellent interlayer adhesiveness even when it exists in a severe environment.

FIG. 1 is a cross-sectional view illustrating an example of the layer configuration of the laminate of the present invention. FIG. 2 is a cross-sectional view illustrating an example of the layer configuration of the laminate of the present invention. FIG. 3 is a cross-sectional view illustrating an example of the layer configuration of the laminate of the present invention. FIG. 4 is a graph showing the relationship between the amount of NaOH added to the fiber material and the electrical conductivity. FIG. 5 is a schematic diagram illustrating the structure of a glass cell for forming a resin layer according to an embodiment.

  Hereinafter, the present invention will be described in detail. The description of the components described below may be made based on representative embodiments or specific examples, but the present invention is not limited to such embodiments.

(Laminate)
The present invention relates to a laminate having a fiber layer, an adhesive layer, and a resin layer in this order. In the laminate, the fibrous layer contains fine fibrous cellulose having a fiber width of 1000 nm or less. The adhesive layer contains a functional group (A) that forms a covalent bond with a (meth) acryloyl group, and is further selected from a functional group (B) that forms a covalent bond with a hydroxyl group and a hydrolyzable group of the functional group (B). At least one. The resin layer contains a polymer of an acrylic monomer.

  FIG. 1 is a cross-sectional view illustrating an example of the layer configuration of the laminate of the present invention. As shown in FIG. 1, the laminate 100 of the present invention includes a fiber layer 10, an adhesive layer 20, and a resin layer 30 in this order. That is, in the laminate 100, the fiber layer 10 and the resin layer 30 are bonded via the bonding layer 20.

  Since the laminate of the present invention has the fiber layer 10 containing fine fibrous cellulose, the adhesive layer 20 containing a specific functional group, and the resin layer 30 containing a polymer of an acrylic monomer, it has excellent transparency and strength. I have. Further, the durability of the laminate of the present invention is good. Here, "good durability" means that the adhesion between the layers of the laminate is excellent, and that good adhesion is exhibited even under severe conditions such as high temperature and high humidity conditions. This is because the functional group (B) contained in the composition forming the adhesive layer 20 is covalently bonded to the hydroxyl group of the fine fibrous cellulose contained in the fibrous layer 10 and is contained in the composition forming the adhesive layer 20. The functional group (A) forms a covalent bond with the acryloyl group contained in the resin layer 30, and the hydroxyl group and the functional group (B) contained in the composition forming the adhesive layer 20 form a covalent bond. It is believed that this is achieved by forming That is, it is considered that a series of cross-linking structures that connect the fiber layer 10 and the resin layer 30 are formed in the adhesive layer 20, so that the adhesion between the layers of the laminate is strengthened.

  The laminate 100 of the present invention may be a three-layer laminate 100 containing at least one fiber layer 10, one adhesive layer 20, and one resin layer 30. It may be a laminate of four or more layers. For example, as shown in FIG. 2, the laminate 100 of the present invention may be a laminate having a combination of the adhesive layer 20 and the resin layer 30 on both surfaces of the fiber layer 10, and may have a five-layer structure. It may be a laminate. Further, as shown in FIG. 3, the laminate 100 of the present invention may be a laminate having a combination of the adhesive layer 20 and the fiber layer 10 on both surfaces of the resin layer.

  When the laminate has a configuration as shown in FIG. 2, the resin layer 30 can function as a layer that coats the surface of the fiber layer 10. When the laminate has a configuration as shown in FIG. 3, the fiber layer 10 may have a function of reinforcing the resin layer 30, and the fiber layer 10 can function as a reinforcing layer. . As described above, each layer can exhibit various functions depending on the application and the configuration. Further, it is preferable that the thickness of each layer is appropriately selected according to the application and the configuration.

  The thickness of the resin layer is preferably at least 1 μm, more preferably at least 3 μm, even more preferably at least 5 μm. When the resin layer functions as a layer for coating the surface of the fiber layer, it may be a thin film. Further, the thickness of the resin layer is preferably 10 mm or less, and more preferably 5 mm or less. When the fiber layer is configured to reinforce the resin layer, the resin layer preferably has a certain thickness.

  The thickness of the fiber layer is preferably at least 1 μm, more preferably at least 3 μm, even more preferably at least 5 μm. The thickness of the fiber layer is preferably 1 mm or less, more preferably 100 μm or less.

  The thickness of the adhesive layer is preferably at least 0.1 μm, more preferably at least 0.5 μm, even more preferably at least 1 μm. The thickness of the adhesive layer is preferably 100 μm or less, more preferably 50 μm or less. By setting the thickness of the adhesive layer within the above range, the interlayer adhesion in the laminate can be more effectively increased.

The laminate of the present invention has excellent adhesion between the layers, and the fiber layer is firmly adhered to the resin layer via the adhesive layer. Specifically, in a cross-cut test based on JIS K 5400 for the laminate, the number of peelings in 100 fiber layers is preferably 10 or less, more preferably 5 or less, and 3 or less. Is more preferred.
The method for evaluating the adhesion in accordance with JIS K 5400 is specifically as follows. First, 100 cross cuts of 1 mm ² were put on the surface of the fiber layer side of the laminate, and a cellophane tape (manufactured by Nichiban Co., Ltd.) was adhered thereon and pressed with a load of 1.5 kg / cm ² , and then 90 ° In the direction, count the number of squares (1 mm ² square squares) peeled off. The number of the cells is defined as the number of peelings in 100 cells.

  The laminate of the present invention is also characterized in that the adhesion between the layers does not decrease even under severe conditions such as high temperature and high humidity conditions. Even when the laminate is placed in a high-temperature and high-humidity condition for a long time, the fiber layer is firmly adhered to the resin layer via the adhesive layer. Specifically, the number of peelings in the 100 masses of the fiber layer when performing a cross-cut test in accordance with JIS K 5400 after placing the laminate at a temperature of 85 ° C. and a relative humidity of 85% for 240 hours is 20. It is preferably at most 10, more preferably at most 10, still more preferably at most 5, particularly preferably at most 3.

  The tensile modulus of the laminate of the present invention is preferably 5 GPa or more, more preferably 7 GPa or more, and even more preferably 9 GPa or more. The tensile modulus of the laminate is a value measured according to JIS P 8113, and is the tensile modulus at a temperature of 23 ° C. and a relative humidity of 50%. As a tensile tester, Tensile Tester CODE SE-064 manufactured by L & W can be used.

  The total light transmittance of the laminate of the present invention is preferably 85% or more, more preferably 87% or more, and even more preferably 90% or more. The total light transmittance of the laminate is a value measured by a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K7361.

  The haze value of the laminate of the present invention is preferably 20% or less, more preferably 15% or less, and even more preferably 10% or less. The haze value of the laminate is a value measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7136.

The laminate of the present invention comprises a resin having a functional group (A) and a hydroxyl group and at least two functional groups (B) on at least one surface of a fiber layer containing fine fibrous cellulose having a fiber width of 1000 nm or less. After forming an adhesive layer by applying a composition containing a compound having, and that is further manufactured by forming a resin layer by further applying a resin composition containing an acrylic monomer on the adhesive layer Is preferred. That is, in the laminate of the present invention, the adhesive layer is preferably a coating adhesive layer, and the resin layer is preferably a coating resin layer. Here, the application adhesive layer is a layer obtained by applying the composition as described above and then curing the composition. The application resin layer is a layer obtained by applying a resin composition containing an acrylic monomer and then curing the resin composition.
In the present invention, by forming the adhesive layer and the resin layer by the above-described method, a series of crosslinked structures that connect the fiber layer and the resin layer are formed in the adhesive layer. For this reason, it is possible to more effectively increase the interlayer adhesion in the laminate.

(Fiber layer)
The fibrous layer contains fine fibrous cellulose having a fiber width of 1000 nm or less. The content of fine fibrous cellulose contained in the fiber layer is preferably at least 60% by mass, more preferably at least 70% by mass, and at least 80% by mass, based on the total mass of the fiber layer. More preferably, it is particularly preferably 90% by mass or more.

<Fine fibrous cellulose>
The fibrous cellulose raw material for obtaining fine fibrous cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Pulp includes wood pulp, non-wood pulp, and deinked pulp. Examples of the wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen bleached kraft. Chemical pulp such as pulp (OKP) is exemplified. In addition, semi-chemical pulp such as semi-chemical pulp (SCP) and chemical ground wood pulp (CGP), mechanical pulp such as groundwood pulp (GP) and thermomechanical pulp (TMP and BCTMP) are exemplified, but not particularly limited. Examples of the non-wood pulp include cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, cellulose isolated from sea squirts and seaweed, and the like, but are not particularly limited. . Examples of the deinked pulp include, but are not particularly limited to, deinked pulp made from waste paper. As the pulp of this embodiment, one of the above-mentioned types may be used alone, or two or more types may be used in combination. Among the above pulp, wood pulp containing cellulose and deinked pulp are preferable in terms of availability. Among wood pulp, chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber refining (fibrillation) is high, and the decomposition of cellulose in pulp is small, and the fineness of long fibers with a large axial ratio is reduced. This is preferable in that fibrous cellulose can be obtained. Among them, kraft pulp and sulfite pulp are most preferably selected. A sheet containing long-fiber microfibrous cellulose having a large axial ratio tends to have high strength.

  The average fiber width of the fine fibrous cellulose is 1000 nm or less when observed with an electron microscope. The average fiber width is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and further preferably 2 nm or more and 10 nm or less, but is not particularly limited. When the average fiber width of the fine fibrous cellulose is less than 2 nm, the physical properties (strength, rigidity, and dimensional stability) of the fine fibrous cellulose tend to be hardly exhibited because they are dissolved in water as cellulose molecules. . The fine fibrous cellulose is, for example, a monofibrous cellulose having a fiber width of 1000 nm or less.

  The measurement of the average fiber width of fine fibrous cellulose by observation with an electron microscope is performed as follows. An aqueous suspension of fine fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less was prepared, and this suspension was cast on a carbon membrane-coated grid subjected to hydrophilization treatment to prepare a TEM observation sample. I do. In the case of including a wide fiber, an SEM image of a surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1,000 times, 5000 times, 10,000 times, or 50,000 times depending on the width of the constituent fibers. However, the sample, observation conditions and magnification are adjusted so as 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 intersect the straight line X.
(2) A straight line Y perpendicular to the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.

  With respect to the observed image satisfying the above conditions, the width of the fiber intersecting with the straight lines X and Y is visually read. In this way, at least three or more sets of images of the non-overlapping surface portion are observed, and the width of the fiber intersecting with the straight line X and the straight line Y is read for each image. Thus, a fiber width of at least 20 × 2 × 3 = 120 fibers is read. The average fiber width of the fine fibrous cellulose (sometimes simply referred to as “fiber width”) is the average value of the fiber widths thus read.

  The fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and particularly preferably 0.1 μm or more and 600 μm or less. By setting the fiber length within the above range, destruction of the crystal region of the fine fibrous cellulose can be suppressed, and the slurry viscosity of the fine fibrous cellulose can be adjusted to an appropriate range. The fiber length of the fine fibrous cellulose can be determined by image analysis using TEM, SEM, and AFM.

The fine fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous cellulose has an I-type crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418 °) monochromated with graphite. Specifically, it can be identified by having typical peaks at two positions near 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less.
The proportion of the type I crystal structure in the fine fibrous cellulose is preferably at least 30%, more preferably at least 50%, even more preferably at least 70%.

  The ratio of the crystal part contained in the fine fibrous cellulose is not particularly limited in the present invention, but it is preferable to use cellulose having a crystallinity determined by X-ray diffraction method of 60% or more. The crystallinity is preferably 65% or more, more preferably 70% or more. In this case, further excellent performance can be expected in terms of heat resistance and low linear thermal expansion coefficient. The crystallinity can be determined by measuring the X-ray diffraction profile and using a pattern thereof according to a conventional method (Seagal et al., Textile Research Journal, Vol. 29, p. 786, 1959).

<Chemical treatment>
Fine fibrous cellulose is obtained by defibrating a cellulose raw material. In addition, in the present invention, it is preferable to add a substituent to the fine fibrous cellulose by subjecting the cellulose raw material to a chemical treatment before the fibrillation treatment. The substituent added to the fine fibrous cellulose is preferably an ionic substituent, more preferably an anionic substituent. Examples of the anionic substituent include a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group), and at least one substituent selected from a carboxyl group and a sulfone group. it can. Among them, the anionic substituent is preferably at least one selected from a phosphate group and a carboxyl group, and more preferably a phosphate group.

  The fine fibrous cellulose used in the present invention preferably has an anionic substituent in an amount of 0.1 mmol / g to 3.5 mmol / g per 1 g (mass) of the fine fibrous cellulose. The fine fibrous cellulose having the above-described anionic substituent in the above ratio is preferable in that it can be made ultrafine by an electrostatic repulsion effect.

<General chemical treatment>
The method for chemically treating the cellulose raw material is not particularly limited as long as it is a method capable of obtaining fine fibers. Examples of the chemical treatment include an acid treatment, an ozone treatment, a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation treatment, an enzyme treatment, and a covalent bond with a functional group in a cellulose or fiber raw material. And the like, which can form a compound.

Examples of acid treatments include Otto van den Berg; Jeffrey R. Capadona; Christoph Weder;
Biomacromolecules 2007, 8, 1353-1357. Specifically, the fine fibrous cellulose is hydrolyzed with sulfuric acid, hydrochloric acid, or the like. The non-crystalline region produced by the high-concentration acid treatment is almost completely decomposed and has short fibers (also called cellulose nanocrystals), which are also included in the fine fibrous cellulose.

  As an example of the ozone treatment, a method described in JP-A-2010-254726 can be exemplified, but is not particularly limited. Specifically, after the fibers are subjected to ozone treatment, they are dispersed in water, and the resulting aqueous suspension of fibers is pulverized.

  As an example of TEMPO oxidation, the method described in Saito T & al. Homogeneous suspensions of individualized microfibrils from TEMPO-catalyzed oxidation of native cellulose. Biomacromolecules 2006, 7 (6), 1687-91 can be mentioned. Specifically, the fibers are subjected to a TEMPO oxidation treatment, then dispersed in water, and the resulting aqueous suspension of the fibers is pulverized.

  Examples of the enzyme treatment include, but are not particularly limited to, the method described in WO2013 / 176033 (the contents described in WO2013 / 176033 are all cited in the specification of the present application). . Specifically, this is a method in which a fiber raw material is treated with an enzyme under the condition that the ratio of the EG activity to the CBHI activity of the enzyme is at least 0.06.

  Examples of the treatment with a compound capable of forming a covalent bond with a functional group in cellulose or a fiber raw material include those described in WO 2013/073652 (PCT / JP2012 / 079743), “Oxic acid containing a phosphorus atom in the structure, And a method using at least one compound selected from polyoxoacids and salts thereof.

<Introduction of anionic substituent>
The fine fibrous cellulose preferably has an anionic substituent. Among them, the anion group is preferably at least one selected from a phosphate group, a carboxyl group and a sulfone group, more preferably at least one selected from a phosphate group and a carboxyl group. Particularly preferred is an acid group.

<Amount of substituent introduced>
The introduction amount of the anionic substituent is not particularly limited, but is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and more preferably 0.3 mmol / g or more per 1 g (mass) of the fine fibrous cellulose. / G or more, more preferably 0.5 mmol / g or more. Further, the amount of the anionic substituent introduced is preferably 3.5 mmol / g or less, more preferably 3.0 mmol / g or less, even more preferably 2.5 mmol / g or less. It is particularly preferred that it is 0 mmol / g or less. By setting the introduction amount of the anionic substituent within the above range, the fineness of the fiber raw material can be facilitated, and the stability of the fine fibrous cellulose can be increased.

<Introduction of phosphate group>
In the present invention, the fine fibrous cellulose preferably has a phosphate group or a substituent derived from the phosphate group.

<Phosphate group introduction step>
The phosphate group introduction step can be performed by reacting at least one selected from a compound having a phosphate group and a salt thereof (hereinafter, referred to as "compound A") with a fiber material containing cellulose. . Such a compound A may be mixed with a dry or wet fiber raw material in the form of a powder or an aqueous solution. As another example, a powder or an aqueous solution of compound A may be added to the slurry of the fiber raw material.

  The phosphate group-introducing step can be performed by reacting at least one compound (compound A) selected from a compound having a phosphate group and a salt thereof with a fiber material containing cellulose. This reaction may be performed in the presence of at least one selected from urea and its derivatives (hereinafter, referred to as “compound B”).

  As an example of a method of causing compound A to act on a fiber raw material in the presence of compound B, a method of mixing powder or an aqueous solution of compound A and compound B with a dry or wet fiber raw material is exemplified. As another example, there is a method of adding a powder or an aqueous solution of the compound A and the compound B to a slurry of a fiber raw material. Among them, the method of adding an aqueous solution of the compound A and the compound B to the fiber material in a dry state or the addition of a powder or an aqueous solution of the compound A and the compound B to the fiber material in a wet state because of high uniformity of the reaction. The method is preferred. Compound A and compound B may be added simultaneously or separately. Alternatively, compound A and compound B to be subjected to the reaction may be first added as an aqueous solution, and excess chemical solution may be removed by pressing. The form of the fiber raw material is preferably in the form of cotton or a thin sheet, but is not particularly limited.

The compound A used in the present embodiment is at least one selected from a compound having a phosphate group and a salt thereof.
Examples of the compound having a phosphate group include, but are not particularly limited to, phosphoric acid, a lithium salt of phosphoric acid, a sodium salt of phosphoric acid, a potassium salt of phosphoric acid, and an ammonium salt of phosphoric acid. Examples of the lithium salt of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. Examples of the sodium salt of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate. Examples of the potassium salt of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate. Examples of the ammonium salt of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate.

  Among these, phosphoric acid, sodium phosphate, from the viewpoint of high efficiency of phosphate group introduction, higher defibration efficiency in the defibration step described later, lower cost, and industrial applicability. Salts, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferred. Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferred.

  In addition, compound A is preferably used as an aqueous solution because the uniformity of the reaction is increased and the efficiency of introducing a phosphate group is increased. The pH of the aqueous solution of the compound A is not particularly limited, but is preferably 7 or less from the viewpoint of increasing the efficiency of phosphate group introduction, and more preferably from 3 to 7 from the viewpoint of suppressing hydrolysis of pulp fibers. The pH of the aqueous solution of compound A may be adjusted, for example, by using a combination of acidic and alkaline compounds among the compounds having a phosphate group, and changing the amount ratio thereof. The pH of the aqueous solution of the compound A may be adjusted by adding an inorganic alkali or an organic alkali to the acidic compound among the compounds having a phosphate group.

  The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to the amount of phosphorus atom, the amount of phosphorus atom added to the fiber material is preferably 0.5% by mass or more and 100% by mass or less, It is more preferably from 50% by mass to 50% by mass, most preferably from 2% by mass to 30% by mass. When the amount of phosphorus atoms added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. If the amount of the phosphorus atom added to the fiber raw material exceeds 100% by mass, the effect of improving the yield will level off and the cost of the compound A to be used will increase. On the other hand, the yield can be increased by setting the amount of phosphorus atoms to be added to the fiber raw material at or below the lower limit.

  Compound B used in this embodiment includes urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzoleinurea, hydantoin and the like. Among these, urea is preferred because it is easy to handle at low cost and easily forms a hydrogen bond with a fiber material having a hydroxyl group.

  Compound B is preferably used as an aqueous solution like compound A. In addition, it is preferable to use an aqueous solution in which both the compound A and the compound B are dissolved because the uniformity of the reaction is enhanced. The amount of compound B to be added to the fiber raw material is preferably 1% by mass or more and 300% by mass or less.

  In addition to compound A and compound B, amides or amines may be included in the reaction system. Examples of the amide include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of the amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine. Among these, it is known that triethylamine particularly works as a good reaction catalyst.

  It is preferable to perform a heat treatment in the phosphoric acid group introduction step. As the heat treatment temperature, it is preferable to select a temperature at which a phosphate group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis of the fiber. Specifically, the temperature is preferably from 50 ° C. to 300 ° C., more preferably from 100 ° C. to 250 ° C., and even more preferably from 150 ° C. to 200 ° C. Further, a vacuum dryer, an infrared heater, and a microwave heater may be used for heating.

  During the heat treatment, while the water is contained in the fiber raw material slurry to which the compound A has been added, if the time for allowing the fiber raw material to stand is long, the compound A dissolved with water molecules moves to the surface of the fiber raw material with drying. I do. Therefore, there is a possibility that unevenness occurs in the concentration of the compound A in the fiber raw material, and the introduction of the phosphate group to the fiber surface may not proceed uniformly. In order to suppress the occurrence of concentration unevenness of the compound A in the fiber raw material due to drying, a very thin sheet-like fiber raw material is used, or the fiber raw material and the compound A are kneaded or kneaded with a kneader or the like, and heated or dried under reduced pressure while stirring. A method may be adopted.

  The heating device used for the heat treatment is preferably a device capable of constantly discharging the water retained by the slurry and the water generated by the addition reaction of the fibers such as the phosphate groups to the hydroxyl groups to the outside of the apparatus system. Are preferred. If the water in the system is constantly drained, the hydrolysis of the phosphate bond, which is the reverse reaction of the phosphorylation, can be suppressed, and the acid hydrolysis of sugar chains in the fiber can also be suppressed. Thus, fine fibers having a high axial ratio can be obtained.

  The time of the heat treatment is affected by the heating temperature, but is preferably 1 second or more and 300 minutes or less, preferably 1 second or more and 1000 seconds or less after the water is substantially removed from the fiber raw material slurry. Preferably, it is 10 seconds or more and 800 seconds or less. In the present invention, by setting the heating temperature and the heating time in an appropriate range, the amount of the phosphoric acid group to be introduced can be within a preferable range.

<Amount of phosphate group introduced>
The amount of phosphate groups introduced is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and more preferably 0.3 mmol / g or more per 1 g (mass) of fine fibrous cellulose. More preferably, it is particularly preferably 0.5 mmol / g or more. Further, the amount of phosphate groups introduced is preferably 3.5 mmol / g or less, more preferably 3.0 mmol / g or less, even more preferably 2.5 mmol / g or less, and 2.0 mmol / g or less. / G or less is particularly preferred. By setting the amount of the phosphoric acid group to be in the above range, the fiber raw material can be easily made finer, and the stability of the fine fibrous cellulose can be increased.

  The amount of the phosphate group introduced into the fiber raw material can be measured by a conductivity titration method. Specifically, by performing the fineness in the defibration process, after treating the obtained fine fibrous cellulose-containing slurry with an ion exchange resin, by determining the change in electrical conductivity while adding an aqueous sodium hydroxide solution, The amount introduced can be measured.

  In the conductivity titration, the curve shown in FIG. 4 is given as the alkali is added. At first, the electrical conductivity sharply decreases (hereinafter, referred to as “first region”). Thereafter, the conductivity starts to slightly increase (hereinafter, referred to as “second region”). Thereafter, the increment of the conductivity increases (hereinafter, referred to as “third region”). That is, three regions appear. Of these, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is equal to the amount of weakly acidic groups in the slurry used for titration. Become equal. When the phosphate group causes condensation, the weakly acidic group is apparently lost, and the amount of alkali required in the second region is smaller than the amount of alkali required in the first region. On the other hand, since the amount of the strongly acidic group coincides with the amount of the phosphorus atom irrespective of the presence or absence of condensation, the amount of the introduced phosphate group (or the amount of the phosphoric acid group) or the amount of the introduced substituent (or the amount of the substituent) is simply referred to. In this case, it indicates the amount of the strongly acidic group. That is, the amount of alkali (mmol) required in the first region of the curve shown in FIG. 4 is divided by the solid content (g) in the slurry to be titrated to obtain a substituent introduction amount (mmol / g).

  The phosphate group introduction step may be performed at least once, but may be repeated a plurality of times. This case is preferable because more phosphate groups are introduced.

<Introduction of carboxyl group>
In the present invention, when the fine fibrous cellulose has a carboxyl group, for example, a compound having a group derived from an oxidizing treatment such as the above-described TEMPO oxidizing treatment or a carboxylic acid, a derivative thereof, or an acid anhydride or a derivative thereof , A carboxyl group can be introduced.

  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, and examples thereof include maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and acid anhydrides of dicarboxylic acid compounds such as itaconic anhydride. Can be

  The derivative of the compound having a carboxyl group is not particularly limited, and examples thereof include imidized products of an acid anhydride of a compound having a carboxyl group and derivatives of an acid anhydride of a compound having a carboxyl group. The imidized product of the acid anhydride of the compound having a carboxyl group is not particularly limited, and examples thereof include imidized products of dicarboxylic acid compounds such as maleimide, succinimide, and phthalimide.

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

<Amount of carboxyl group introduced>
The amount of the carboxyl group introduced is preferably 0.1 mmol / g or more, more preferably 0.2 mmol / g or more, and more preferably 0.3 mmol / g or more per 1 g (mass) of the fine fibrous cellulose. Is more preferable, and it is particularly preferable that it is 0.5 mmol / g or more. Further, the amount of carboxyl groups introduced is preferably 3.5 mmol / g or less, more preferably 3.0 mmol / g or less, even more preferably 2.5 mmol / g or less, and 2.0 mmol / g or less. g is particularly preferable. By setting the introduction amount of the carboxyl group within the above range, the fineness of the fiber raw material can be easily made, and the stability of the fine fibrous cellulose can be increased.

<Introduction of cationic substituent>
In the present embodiment, a cationic substituent as an ionic substituent may be introduced into the fine fibrous cellulose. For example, a cationic substituent can be introduced into the fiber raw material by adding a cationizing agent and an alkali compound to the fiber raw material and reacting them.
As the cationizing agent, those having a quaternary ammonium group and having a group that reacts with the hydroxyl group of cellulose can be used. Examples of the group that reacts with the hydroxyl group of cellulose include an epoxy group, a functional group having a halohydrin structure, a vinyl group, and a halogen group. Specific examples of the cationizing agent include glycidyltrialkylammonium chlorides such as glycidyltrimethylammonium chloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride, and halohydrin-type compounds thereof.
The alkali compound contributes to promoting the cationization reaction. Alkali compounds include alkali metal hydroxides or alkaline earth metal hydroxides, alkali metal carbonates or alkaline earth metal carbonates, alkali metal phosphates and alkaline earth metal phosphates. Or an alkali alkali compound such as ammonia, an aliphatic amine, an aromatic amine, an aliphatic ammonium, an aromatic ammonium, a heterocyclic compound, and a hydroxide, carbonate, or phosphate thereof. It may be. The amount of the introduced cationic substituent can be measured by, for example, elemental analysis or the like.

<Alkali treatment>
In the case of producing fine fibrous cellulose, an alkali treatment can be performed between the substituent introduction step and the defibration step described below. The method of the alkali treatment is not particularly limited, and includes, for example, a method of immersing the phosphate group-introduced fiber in an alkaline solution.
The alkali compound contained in the alkali solution is not particularly limited, but may be an inorganic alkali compound or an organic alkali compound. The solvent in the alkaline solution may be either water or an organic solvent. The solvent is preferably a polar solvent (water or a polar organic solvent such as alcohol), and more preferably an aqueous solvent containing at least water.
Among the alkaline solutions, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is particularly preferable because of its high versatility.

The temperature of the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 ° C or more and 80 ° C or less, more preferably 10 ° C or more and 60 ° C or less.
The immersion time in the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, more preferably 10 minutes or more and 20 minutes or less.
The amount of the alkali solution used in the alkali treatment is not particularly limited, but is preferably from 100% by mass to 100,000% by mass, and more preferably from 1,000% by mass to 10,000% by mass, based on the absolute dry mass of the phosphate group-introduced fiber. Is more preferable.

  Before the alkali treatment step, the phosphate group-introduced fiber may be washed with water or an organic solvent in order to reduce the amount of the alkali solution used in the alkali treatment step. After the alkali treatment, in order to improve the handleability, it is preferable to wash the alkali-treated phosphate group-introduced fiber with water or an organic solvent before the fibrillation treatment step.

<Fibrillation processing>
The ionic substituent-introduced fiber is defibrated in a defibration process. In the defibration treatment step, the fibers are usually defibrated using a defibration treatment device to obtain a slurry containing fine fibrous cellulose, but the treatment device and treatment method are not particularly limited.
As the defibrating device, a high-speed defibrating machine, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultra-high-pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, or the like can be used. Alternatively, as the defibrating device, use is made of a wet crushing device such as a disc type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater. Can also. The defibrating device is not limited to the above. Preferred defibration treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by the pulverized media and are less likely to cause contamination.

  In the case of the defibration treatment, it is preferable to dilute the fiber raw material with water or an organic solvent alone or in combination to form a slurry, but there is no particular limitation. As the dispersion medium, a polar organic solvent can be used in addition to water. Preferred polar organic solvents include, but are not particularly limited to, alcohols, ketones, ethers, dimethylsulfoxide (DMSO), dimethylformamide (DMF), and dimethylacetamide (DMAc). Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butyl alcohol. Examples of ketones include acetone and methyl ethyl ketone (MEK). Examples of the ethers include diethyl ether and tetrahydrofuran (THF). The dispersion medium may be one type or two or more types. Further, the dispersion medium may contain a solid content other than the fiber raw material, for example, urea having a hydrogen bonding property.

  In the present invention, the fibrillation treatment may be performed after the fine fibrous cellulose is concentrated and dried. In this case, the method of concentration and drying is not particularly limited, and examples thereof include a method of adding a concentrating agent to a slurry containing fine fibrous cellulose, and a method of using a commonly used dehydrator, press, or dryer. In addition, known methods, for example, methods described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used. Further, the concentrated fine fibrous cellulose may be formed into a sheet. The sheet may be pulverized to perform a defibration treatment.

  Apparatuses used for pulverizing fine fibrous cellulose include a high-speed defibrator, a grinder (stone mill type pulverizer), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type pulverizer, a ball mill, a bead mill, a disk type refiner, and a conical. A wet pulverizer such as a refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater can be used, but is not particularly limited.

  The fine fibrous cellulose having a phosphate group obtained by the above-described method is a fine fibrous cellulose-containing slurry, and may be used after being diluted with water so as to have a desired concentration. The fine fibrous cellulose-containing slurry is formed into a sheet by a method described below, and a fibrous layer is formed.

<Fiber layer density>
The density of the fiber layer is preferably at least 1.0 g / cm ^3, more preferably at least 1.2 g / cm ³ , even more preferably at least 1.4 g / cm ³ . Further, the density of the fiber layer is preferably 2.0 g / cm ³ or less. The density of the fiber layer is calculated from the basis weight and thickness of the fiber layer according to JIS P8118. The basis weight of the fiber layer can be calculated according to JIS P8124. When the fiber layer contains an optional component other than the fine fibrous cellulose, the density of the fiber layer is a density containing an optional component other than the fine fibrous cellulose.

The present invention is also characterized in that the fiber layer is a non-porous layer. Here, that the fiber layer is non-porous means that the density of the entire fiber layer is 1.0 g / cm ³ or more. If the density of the entire fiber layer is 1.0 g / cm ³ or more, it means that the porosity contained in the fiber layer is suppressed to a predetermined value or less, and is distinguished from a porous sheet or layer. .
The fact that the fiber layer is non-porous is also characterized by the fact that the porosity is 15% by volume or less. The porosity of the fiber layer referred to here is simply determined by the following equation (a).
Formula (a): Porosity (% by volume) = [1-B / (M × A × t)] × 100
Here, A is the area (cm ² ) of the fiber layer, t is the thickness (cm) of the fiber layer, B is the mass (g) of the fiber layer, and M is the density of cellulose.

<Other components>
Other components contained in the fiber layer include, for example, hydrophilic polymers and organic ions. Examples of the hydrophilic polymer include polyethylene glycol, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.), casein, dextrin, starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), Examples include polyethylene oxide, polyvinylpyrrolidone, polyvinyl methyl ether, polyacrylates, polyacrylamide, alkyl acrylate copolymers, and urethane copolymers. Examples of the organic ion include a tetraalkylammonium ion and a tetraalkylphosphonium ion. Examples of the tetraalkylammonium ion include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, tetraheptylammonium ion, tributylmethylammonium ion, lauryltrimethyl Examples include ammonium ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, octyldimethylethylammonium ion, lauryldimethylethylammonium ion, didecyldimethylammonium ion, lauryldimethylbenzylammonium ion, and tributylbenzylammonium ion. Examples of the tetraalkylphosphonium ion include a tetramethylphosphonium ion, a tetraethylphosphonium ion, a tetrapropylphosphonium ion, a tetrabutylphosphonium ion, and a lauryltrimethylphosphonium ion. Examples of the tetrapropyl onium ion and the tetrabutyl onium ion include a tetra n-propyl onium ion and a tetra n-butyl onium ion, respectively.

(Adhesive layer)
The adhesive layer contains a functional group (A) that forms a covalent bond with a (meth) acryloyl group, and is further selected from a functional group (B) that forms a covalent bond with a hydroxyl group and a hydrolyzable group of the functional group (B). At least one is included. That is, the adhesive layer includes the functional group (A) and the functional group (B) or a group derived from the functional group (B). In the present invention, by including such a plurality of types of functional groups in the adhesive layer, the interlayer adhesion in the laminate can be increased.

  The adhesive layer preferably contains a compound a having a functional group (A) and a compound b having a functional group (B), but at least one functional group (A) and one functional group (B) are included in one molecule. It may contain compounds contained therein. The compound a having the functional group (A) is preferably a polymer (resin) having the functional group (A), and both the functional group (A) and the functional group (B) are contained in one molecule. In such a case, such a compound is also preferably a polymer (resin).

The functional group (A) that forms a covalent bond with the (meth) acryloyl group includes a (meth) acryloyl group (H ₂ C = CR ¹ -C (＝ O) —) and H ₂ C = CR ² —CH ( It is preferably at least one selected from the group represented by -OH)-. In the specification of the present application, “(meth) acryloyl group” indicates an acryloyl group or a methacryloyl group. R ¹ and R ² are a hydrogen atom or a methyl group.
In the present invention, a polymer having a functional group (A) (resin) is (meth) acryloyl groups, ^{_{and, H 2 C = CR 2 -CH}} (-OH) - at least one selected from the group represented by is preferably an acrylic resin having a (meth) acryloyl groups, ^{_{and, H 2 C = CR 2 -CH}} (-OH) - is an acrylic resin having at least one grafted polymer is selected from the groups represented more preferably, (meth) acryloyl groups, ^{_{and, H 2 C = CR 2 -CH}} (-OH) - and particularly preferably both a group represented by is an acrylic resin obtained by graft polymerization.

The functional group (B) forming a covalent bond with a hydroxyl group is preferably at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an alkoxysilyl group, a silanol group and an oxazoline group, and is an isocyanate group. Is more preferred.
The hydrolyzable group of the functional group (B) is a group obtained by hydrolyzing the above-mentioned functional group, and is a group derived from the functional group (B).

  The compound b having a functional group (B) is preferably an isocyanate compound. Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. The isocyanate compound includes a polyisocyanate of a biuret type, a nullate type, an adduct type and the like, and such a polyisocyanate can also be used. Among them, a nurate-type polyisocyanate is preferred from the viewpoint of suppressing coloring due to heating and deterioration over time. In addition, the compound b detected in the adhesive layer may be a hydrolyzable group obtained by hydrolyzing at least one isocyanate group of the above isocyanate compound.

  The functional group (A) is a group that forms a covalent bond with an acryloyl group of the acrylic monomer polymer contained in the resin layer. The functional group (B) is a group that forms a covalent bond with a hydroxyl group of the fine fibrous cellulose contained in the fiber layer. Further, the functional group (B) is a group that is covalently bonded to a hydroxyl group contained in the compound having the functional group (A). For example, the functional group (B) is a group covalently bonded to a hydroxyl group in the following structure contained in the adhesive layer, but the group to which the functional group (B) is covalently bonded is not limited thereto.

In the above structural formula, R ² represents a hydrogen atom or a methyl group.

  For example, a compound a having at least one functional group (A) and a hydroxyl group and a compound b having two or more functional groups (B) in one molecule are contained in an adhesive composition for forming an adhesive layer. The hydroxyl group of the compound a first forms a covalent bond with the first functional group (B) of the compound b, and the functional group (A) of the compound a is acryloyl of the acrylic monomer polymer contained in the resin layer. Form a covalent bond with the group. Then, the second functional group (B) of the compound b forms a covalent bond with a hydroxyl group of the fine fibrous cellulose contained in the fibrous layer. As described above, the fine fibrous cellulose contained in the fiber layer and the polymer of the acrylic monomer contained in the resin layer are linked by a crosslinked structure in which the respective functional groups of the compound a and the compound b are covalently bonded. That is, the component contained in the adhesive layer forms a covalent bond with both the component contained in the fiber layer and the component contained in the resin layer. Since the adhesive layer includes the above-described series of crosslinked structures, it is considered that the adhesion between the layers in the laminate is improved.

The adhesive layer is preferably a coating adhesive layer formed by coating, and the composition (coating solution) forming the adhesive layer includes a compound a having at least one functional group (A) and a hydroxyl group, It is preferable to include a compound b having two or more groups (B) in one molecule. Compound a (meth) acryloyl groups, ^{_{and, H 2 C = CR 2 -CH}} (-OH) - It is more preferably one having one by at least one group represented by. When two or more groups represented by H ₂ C ＝ CR ² —CH (—OH) — are included as the functional group (A) included in the compound a, the first H ₂ C ＝ CR ² The group represented by —CH (—OH) — is counted as the functional group (A), and the second group represented by H ₂ C ＝ CR ² —CH (—OH) — is the number of hydroxyl groups. Is counted as
The formation of the adhesive layer includes a step of curing after applying such a composition, and in this curing step, each functional group forms a covalent bond. In the cured adhesive layer, the remaining functional groups (A) and (B) not subjected to the covalent bond are detected. In addition, since the functional group (B) contained in the adhesive layer may be easily hydrolyzed, even if a hydrolyzable group of the functional group (B) is detected from the adhesive layer instead of the functional group (B). Good. Alternatively, a structure in which each functional group is covalently bonded may be detected to confirm that each functional group is included.

The functional group (B) is a group that forms a covalent bond with a hydroxyl group of the fine fibrous cellulose contained in the fibrous layer, but may be formed with a covalent bond with another substituent of the fine fibrous cellulose. Good. For example, a covalent bond may be formed with —O ⁻ Na ⁺ of a phosphate group, which is an ionic substituent of fine fibrous cellulose.

  Examples of the device for detecting the functional group (A), the functional group (B), and the hydrolyzable group of the functional group (B) include a nuclear magnetic resonance analyzer, an infrared spectrometer, an X-ray photoelectron analyzer, and a Raman spectrometer. And the like. When detecting the functional group (A), the functional group (B), and the hydrolyzable group of the functional group (B) contained in the adhesive layer, the cross section of the adhesive layer may be analyzed. After polishing and exposing the adhesive layer, the polished surface may be analyzed.

  The adhesive layer preferably contains a resin, and more preferably contains a polymer (resin) having a functional group (A). That is, the adhesive layer is preferably a layer obtained by polymerizing and curing a curable composition containing a curable monomer component constituting such a resin by a known curing method. Examples of the curing method include thermal curing and radiation curing, and thermal curing is preferred. In addition, examples of the radiation include infrared light, visible light, ultraviolet light, and an electron beam. Preferably, the light is electromagnetic light having a wavelength of 1 nm or more and 1000 nm or less. More preferably, it is an electromagnetic wave having a wavelength of 200 nm or more and 450 nm or less, and further preferably, ultraviolet light having a wavelength of 300 nm or more and 400 nm or less.

  The curable composition forming the adhesive layer preferably contains a polymerization initiator. For this reason, since at least a part of the polymerization initiator remains in the adhesive layer, the adhesive layer preferably contains the polymerization initiator. When the curable composition contains a polymerization initiator, the hardness of the adhesive layer can be adjusted.

  It is preferable to add a thermal polymerization initiator that generates a radical or an acid by heating to the curable composition. It is also preferable to add a photopolymerization initiator which generates radicals and acids by radiation such as ultraviolet rays to the curable composition. Note that a method may be adopted in which both a thermal polymerization initiator and a photopolymerization initiator are added to the curable composition, and polymerization is performed by a combination of heat and light.

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

  The amount of the thermal polymerization initiator to be added is preferably 0.1% by mass or more and 2% by mass or less, more preferably 0.3% by mass or more and 1% by mass or less based on the total mass of the curable monomer component. preferable.

  Examples of the photopolymerization initiator include a photoradical generator and a photocationic polymerization initiator. The photopolymerization initiator may be used alone or in combination of two or more.

  Examples of the photo radical generator include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, and 2,4,6-trimethylbenzoyldiphenyl Hosifine oxide and the like. Among these, benzophenone or 2,4,6-trimethylbenzoyldiphenylphosphine oxide is preferred.

  A photocationic polymerization initiator is a compound that initiates cationic polymerization by irradiation with radiation such as ultraviolet rays or electron beams, and examples thereof include aromatic sulfonium salts, aromatic iodonium salts, aromatic diazonium salts, and aromatic ammonium salts. No.

  As the aromatic sulfonium salt, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfidebishexafluoroantimonate, bis [4- (diphenylsulfonio) ) Phenyl] sulfide bishexafluoroborate, bis [4- (diphenylsulfonio) phenyl] sulfidetetrakis (pentafluorophenyl) borate, diphenyl-4- (phenylthio) phenylsulfonium hexafluoro, diphenyl-4- (phenylthio) Phenylsulfonium hexafluoroantimonate, diphenyl-4- (phenylthio) phenylsulfonium tetrafluoroborate, diphenyl-4- (phenylthio) phenylsulfo 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)) phenylsulfonio) phenyl] sulfidebishexafluoroantimonate , Bis [4- (di (4- (2-hydroxyethoxy)) phenylsulfonio) phenyl] sulfide tetrafluoroborate, or bis [4- (di (4- (2 Hydroxyethoxy)) phenylsulfonyl O) phenyl] sulfide tetrakis (pentafluorophenyl) borate, and the like.

  As the aromatic iodonium salt, 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.

  Examples of the aromatic diazonium salt include phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, and diphenyliodonium tetrakis (pentafluorophenyl) borate.

  Examples of the aromatic ammonium salt include 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, 1-benzyl-2-cyanopyridinium tetrafluoroborate, 1-benzyl-2- Cyanopyridinium tetrakis (pentafluorophenyl) borate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluorophosphate, 1- (naphthylmethyl) -2-cyanopyridinium hexafluoroantimonate, 1- (naphthylmethyl) -2- And cyanopyridinium tetrafluoroborate, 1- (naphthylmethyl) -2-cyanopyridinium tetrakis (pentafluorophenyl) borate and the like. (2,4-cyclopentadien-1-yl) [(1-methylethyl) benzene] -iron salt includes (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 and the like.

  Commercial products of these photocationic polymerization initiators include, for example, UVI6990 and UVI6979 manufactured by Union Carbide, SP-150, SP-170 or SP-172 manufactured by ADEKA, Irgacure 261 or Irgacure manufactured by Ciba Geigy. 250, RHODORSIL PI2074, JMF-2456 manufactured by Rhodia, or San Aid SI-60L, SI-80L, SI-100L, SI-110L, SI-180L, or SI-100L manufactured by Sanshin Chemical Industry Co., Ltd. .

  Further, in addition to the photocationic polymerization initiator, a curing agent for curing the cationically polymerizable monomer may be added. Examples of the curing agent include amine compounds, compounds such as polyaminoamide compounds synthesized from amine compounds, tertiary amine compounds, imidazole compounds, hydrazide compounds, melamine compounds, acid anhydrides, phenol compounds, and heat-latent cationic polymerization catalysts. Or dicyanamide and its derivatives.

  In addition, a photosensitizer can be added. Specific examples include pyrene, perylene, acridine orange, thioxanthone, 2-chlorothioxanthone, and benzoflavin.

  The addition amount of the photopolymerization initiator is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 2% by mass or less based on the total mass of the curable monomer component. More preferably, it is 0.05% by mass or more and 0.1% by mass or less.

(Resin layer)
The resin layer contains a polymer of an acrylic monomer. The resin layer is preferably a coating resin layer formed by coating, and the coating liquid (resin composition) for forming the resin layer preferably contains an acrylic monomer.

  The resin layer is preferably a coating resin layer formed by coating, and is preferably a layer obtained by polymerizing and curing a resin composition containing an acrylic monomer by a known curing method. The curing method includes, for example, heat curing, radiation curing, and the like, and is preferably radiation curing.

  The resin composition forming the resin layer preferably contains a polymerization initiator. For this reason, since at least a part of the polymerization initiator remains in the resin layer, the resin layer preferably contains the polymerization initiator. In addition, as a polymerization initiator added to a resin composition, the above-mentioned thermal polymerization initiator and photopolymerization initiator can be illustrated.

  The coating liquid (resin composition) for forming the resin layer may contain an acrylic monomer or a prepolymer of the acrylic monomer. The prepolymer may be composed of one type of acrylic monomer described below, or may be composed of a combination of two or more types. Further, the prepolymer may be a copolymer in which an acrylic monomer described later is copolymerized with a urethane structure or an epoxy structure.

  As the acrylic monomer, for example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, neopentyl Glycol adipate di (meth) acrylate, neopentyl glycol hydroxypivalate di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, EO-modified di (meth) acrylate phosphate , Allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth ) Acrylate, diventerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanate Nurate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol penta (meth) acrylate propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meta) ) Acrylate, 1,10-decanediol diacrylate and the like. In particular, the acrylic monomer is preferably at least one selected from pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and 1,10-decanediol diacrylate. The acrylic monomers may be used alone or in combination of two or more.

  Further, as the acrylic monomer, it is also preferable to use a monofunctional alkyl (meth) acrylate together with the above-mentioned polyfunctional acrylic monomer. Examples of the monofunctional alkyl (meth) acrylate include, for example, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, N-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, lauryl (meth) acrylate, (meth) ) Stearyl acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like.

  An acrylic resin containing pentaerythritol tetraacrylate or dipentaerythritol hexaacrylate as a monomer component tends to have a large shrinkage when cured. For this reason, when such a monomer component is used, it tends to be more difficult to enhance the adhesiveness between the adhesive layer and the fiber layer and the resin layer, but in the present invention, the adhesive layer is formed of a specific functional group. , The interlayer adhesion was successfully improved even when a monomer component having a large degree of shrinkage upon curing was used.

(Inorganic film laminate)
The laminate of the present invention may further have an inorganic film (hereinafter, also referred to as an inorganic layer). The inorganic layer may be laminated on the fiber layer side, or may be laminated on the resin layer side. Further, the inorganic layers may be laminated on both sides of the laminate.

  The material constituting the inorganic layer is not particularly limited, but includes, for example, aluminum, silicon, magnesium, zinc, tin, nickel, and titanium; oxides, carbides, nitrides, oxycarbides, oxynitrides, or oxycarbonitrides thereof. Or a mixture thereof. From the viewpoint that high moisture resistance can be stably maintained, silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxycarbide, aluminum oxynitride, or these Mixtures are preferred.

  The method for forming the inorganic layer is not particularly limited. Generally, a method of forming a thin film is roughly classified into a chemical vapor deposition method (Chemical Vapor Deposition, CVD) and a physical film formation method (Physical Vapor Deposition, PVD), and any method may be employed. . Specific examples of the CVD method include plasma CVD using plasma, catalytic chemical vapor deposition (Cat-CVD) in which a material gas is catalytically thermally decomposed using a heated catalyst, and the like. Specific examples of the PVD method include vacuum deposition, ion plating, and sputtering.

  As a method for forming the inorganic layer, an atomic layer deposition (ALD) method can also be employed. The ALD method is a method of forming a thin film in atomic layer units by alternately supplying source gases of respective elements constituting a film to be formed to a surface on which a layer is formed. Although there is a disadvantage that the film formation rate is low, there is an advantage over a plasma CVD method that a surface having a complicated shape can be covered finely and a thin film with few defects can be formed. Further, the ALD method has an advantage that the film thickness can be controlled on the order of nanometers, and it is relatively easy to cover a wide surface. Further, in the ALD method, by using plasma, an improvement in the reaction rate, a low-temperature process, and a reduction in unreacted gas can be expected.

  Although the thickness of the inorganic layer is not particularly limited, for example, when the purpose is to exhibit moisture-proof performance, it is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more. The thickness of the inorganic layer is preferably 1,000 nm or less, more preferably 800 nm or less, and still more preferably 600 nm or less, from the viewpoint of transparency and flexibility.

(Production method of laminate)
The present invention also relates to a method for manufacturing a laminate. The manufacturing process of the laminate of the present invention includes a process of obtaining a fiber layer containing fine fibrous cellulose having a fiber width of 1000 nm or less, and a process of forming a covalent bond with a (meth) acryloyl group on at least one surface of the fiber layer. A step of applying a composition containing a group (A) and a functional group (B) that forms a covalent bond with a hydroxyl group to form an adhesive layer, and a step of applying a resin composition containing an acrylic monomer to form a resin layer And a step.

<Step of obtaining fiber layer containing fine fibrous cellulose>
The step of obtaining a fibrous layer containing fine fibrous cellulose includes a step of applying a fine fibrous cellulose-containing slurry on a substrate or a step of paper-making the fine fibrous cellulose-containing slurry. Above all, the step of obtaining a fibrous layer containing fine fibrous cellulose preferably includes a step of applying a fine fibrous cellulose-containing slurry on a substrate.

<Coating process>
In the coating step, a sheet (fibrous layer) is obtained by applying a fine fibrous cellulose-containing slurry onto a base material, and drying and drying the fine fibrous cellulose-containing sheet from the base material. It is a process. The sheet can be continuously produced by using the coating device and the long base material. The concentration of the slurry to be applied is not particularly limited, but is preferably from 0.05% by mass to 5% by mass.

  The quality of the base material used in the coating step is not particularly limited, but those having high wettability with respect to the fine fibrous cellulose-containing slurry may be able to suppress shrinkage of the sheet during drying, but may be formed after drying. It is preferable to select a sheet that can be easily peeled off. Among them, a resin plate or a metal plate is preferable, but not particularly limited. For example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, and polyvinylidene chloride plates, and metal plates such as aluminum plates, zinc plates, copper plates, and iron plates, and those whose surfaces are oxidized, stainless steel A plate, a brass plate, or the like can be used.

  In the coating process, when the viscosity of the fine fibrous cellulose-containing slurry is low and spreads on the base material, in order to obtain a fine fibrous cellulose-containing sheet having a predetermined thickness and a basis weight, a dam is formed on the base material. Frame may be fixed and used. The quality of the damming frame is not particularly limited, but it is preferable to select a sheet that can easily peel off the end of the sheet attached after drying. Among them, those formed from a resin plate or a metal plate are preferable, but are not particularly limited. For example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, and polyvinylidene chloride plates, and metal plates such as aluminum plates, zinc plates, copper plates, and iron plates, and those whose surfaces are oxidized, stainless steel Plates, brass plates and the like can be used.

  As a coating machine for applying the fine fibrous cellulose-containing slurry, for example, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, or the like can be used. A die coater, a curtain coater, and a spray coater are preferable because the thickness can be made more uniform.

  The coating temperature is not particularly limited, but is preferably from 20 ° C to 45 ° C, more preferably from 25 ° C to 40 ° C, even more preferably from 27 ° C to 35 ° C. When the coating temperature is equal to or higher than the lower limit, the slurry containing fine fibrous cellulose can be easily applied. When the coating temperature is equal to or lower than the upper limit, volatilization of the dispersion medium during coating can be suppressed.

In the coating step, it is preferable to apply the slurry so that the finished basis weight of the sheet is 10 g / m ² or more and 100 g / m ² or less, preferably 20 g / m ² or more and 50 g / m ² or less. By coating so that the basis weight is within the above range, a fiber layer having excellent strength can be obtained.

  The step of obtaining the fibrous layer containing fine fibrous cellulose preferably includes a step of drying the fine fibrous cellulose-containing slurry applied on the substrate. The drying method is not particularly limited, but may be any of a non-contact drying method, a method of drying while restraining a sheet, and a combination thereof.

  The non-contact drying method is not particularly limited, but a method of drying by heating with hot air, infrared rays, far infrared rays or near infrared rays (heat drying method), and a method of drying by vacuum (vacuum drying method) may be applied. Can be. The heat drying method and the vacuum drying method may be combined, but usually, the heat drying method is applied. Drying by infrared rays, far infrared rays or near infrared rays can be performed using an infrared ray device, a far infrared ray device or a near infrared ray device, but is not particularly limited. The heating temperature in the heating and drying method is not particularly limited, but is preferably from 20 ° C to 120 ° C, more preferably from 25 ° C to 105 ° C. When the heating temperature is equal to or higher than the lower limit, the dispersion medium can be quickly volatilized. When the heating temperature is equal to or lower than the upper limit, the cost required for heating can be suppressed and the fine fibrous cellulose can be prevented from being discolored by heat. .

  After drying, the obtained fine fibrous cellulose-containing sheet is peeled off from the base material, but when the base material is a sheet, the fine fibrous cellulose-containing sheet and the base material are wound while being laminated, and the fine fibrous Immediately before using the cellulose-containing sheet, the fine fibrous cellulose-containing sheet may be peeled off from the process substrate.

<Paper making process>
The step of obtaining a fibrous layer containing fine fibrous cellulose may include a step of paper-making a slurry containing fine fibrous cellulose. Examples of the paper machine in the paper making process include a continuous paper machine of a fourdrinier type, a circular net type, an inclined type, and the like, and a multi-layered laminating paper machine combining these. In the papermaking step, known papermaking such as hand-making may be performed.

  In the papermaking process, the fine fibrous cellulose-containing slurry is filtered and dehydrated on a wire to obtain a wet-sheet state sheet, and then pressed and dried to obtain a sheet. The concentration of the slurry is not particularly limited, but is preferably 0.05% by mass or more and 5% by mass or less. When filtering and dewatering the slurry, the filter cloth at the time of filtration is not particularly limited, but it is important that the fine fibrous cellulose does not pass through and the filtration speed is not too slow. Such a filter cloth is not particularly limited, but a sheet, a woven fabric, and a porous membrane made of an organic polymer are preferable. The organic polymer is not particularly limited, but is preferably a non-cellulose organic polymer such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and the like. Specific examples include, but are not particularly limited to, a porous film of polytetrafluoroethylene having a pore size of 0.1 μm to 20 μm, for example, 1 μm, and a polyethylene terephthalate or polyethylene fabric having a pore size of 0.1 μm to 20 μm, for example, 1 μm.

  A method for producing a sheet from the fine fibrous cellulose-containing slurry is not particularly limited, and examples thereof include a method using a production apparatus described in WO2011 / 113567. This manufacturing apparatus discharges a slurry containing fine fibrous cellulose onto the upper surface of the endless belt, squeezes a dispersion medium from the discharged slurry to generate a web, and dries the web to form a fiber sheet. Drying section to produce. An endless belt is provided 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 dehydration method that can be used in the present invention is not particularly limited, and includes a dehydration method that is generally used in the production of paper. A dehydration method using a long net, a circular net, an inclined wire, and the like, followed by a dehydration method using a roll press. Is preferred. The drying method is not particularly limited, but includes a method used in the production of paper. For example, a method using a cylinder dryer, a Yankee dryer, hot air drying, a near infrared heater, an infrared heater, or the like is preferable.

<Step of forming adhesive layer>
In the step of forming the adhesive layer, a composition comprising a functional group (A) forming a covalent bond with a (meth) acryloyl group and a functional group (B) forming a covalent bond with a hydroxyl group on at least one surface of the fiber layer. Apply things.

Here, as the functional group (A) and the functional group (B), each of the above-described functional groups is preferably selected. Among these functional groups (A) are (meth) acryloyl group, ^{_{and, H 2 C = CR 2 -CH}} (-OH) - is preferably at least one selected from the group represented by the functional group ( B) is preferably at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an alkoxysilyl group, a silanol group and an oxazoline group.

  The composition containing the functional group (A) and the functional group (B) includes a compound a having at least one functional group (A) and a hydroxyl group, and a compound b having at least two functional groups (B). However, a compound having at least one functional group (A) and one functional group (B) in one molecule may be included.

The compound a having at least one functional group (A) and one hydroxyl group is preferably a polymer (resin) having the functional group (A). Further, a polymer having a functional group (A) (resin) is (meth) acryloyl groups, ^{_{and, H 2 C = CR 2 -CH}} (-OH) - acrylic having at least one selected from the group represented by A resin is preferable, and an acrylic resin obtained by graft polymerization of at least one selected from a (meth) acryloyl group and a group represented by H ₂ C ＝ CR ² —CH (—OH) — is particularly preferable. preferable.

  The compound b having at least two functional groups (B) is preferably an isocyanate compound. Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. The isocyanate compound includes a polyisocyanate of a biuret type, a nullate type, an adduct type and the like, and such a polyisocyanate can also be used. Among them, a nurate-type polyisocyanate is preferred from the viewpoint of suppressing coloring due to heating and deterioration over time.

  Compound a preferably has at least one functional group (A) and at least one hydroxyl group. The hydroxyl group of compound a first forms a covalent bond with the first functional group (B) of compound b, The functional group (A) forms a covalent bond with an acryloyl group of the acrylic monomer polymer contained in the resin layer. Then, the second functional group (B) of the compound b forms a covalent bond with a hydroxyl group of the fine fibrous cellulose contained in the fibrous layer. As described above, the fine fibrous cellulose contained in the fiber layer and the polymer of the acrylic monomer contained in the resin layer are linked by a crosslinked structure in which the respective functional groups of the compound a and the compound b are covalently bonded.

  The composition containing the functional group (A) and the functional group (B) may contain the functional group (B) in an amount of 0.5 mol or more and 5.0 mol or less per 1 mol of the functional group (A). More preferably, it is contained in an amount of 0.5 mol or more and 3.0 mol or less. By setting the molar ratio of the functional group (B) to 1 mol of the functional group (A) within the above range, a crosslinked structure can be formed more effectively, and the interlayer adhesion in the laminate can be further increased. it can.

  The composition containing the functional group (A) and the functional group (B) preferably further contains a polymerization initiator. Examples of the polymerization initiator include the above-described polymerization initiators. Above all, it is preferable that the composition containing the functional group (A) and the functional group (B) contains a photopolymerization initiator. By including the photopolymerization initiator in the composition containing the functional group (A) and the functional group (B), the hardness of the adhesive layer can be further increased by the radiation applied when the resin layer is cured.

  The composition containing the functional group (A) and the functional group (B) may further contain a solvent. Examples of the solvent include esters such as ethyl acetate, butyl acetate and propyl acetate; ketones such as methyl ethyl ketone, methyl isobutyl, dibutyl ketone and cyclohexanone; and organic solvents such as aromatics and hydrocarbons such as toluene, xylene and hexane. No.

  In the step of forming the adhesive layer, a composition comprising a functional group (A) forming a covalent bond with a (meth) acryloyl group and a functional group (B) forming a covalent bond with a hydroxyl group on at least one surface of the fiber layer. Apply things. As a coating machine that can be used in the coating step, for example, a bar coater, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, or the like can be used.

  After the application, a polymerization step is preferably provided, and a thermal polymerization step is more preferably provided. In the thermal polymerization step, for example, it is preferable to heat at 70 to 200 ° C. for 0.1 to 10 hours. In the thermal polymerization step, for example, a method of drying by heating with hot air, infrared rays, far infrared rays or near infrared rays (heat drying method), or a method of drying under vacuum (vacuum drying method) can be applied.

In the polymerization step, a photopolymerization step may be employed, or the thermal polymerization step and the photopolymerization step may be performed simultaneously. In this case, photopolymerization step, the 450nm UV light below or 300 nm, it is preferable to irradiate with 10 mJ / cm ² or more 8000 mJ / cm ² or less.

<Step of forming resin layer>
In the step of forming the resin layer, a resin composition containing at least one selected from an acrylic monomer and a prepolymer of an acrylic monomer is applied.
Examples of the acrylic monomer contained in the resin composition include the above-described acrylic monomers. In particular, the acrylic monomer is preferably at least one selected from pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and 1,10-decanediol diacrylate. Examples of the prepolymer of the acrylic monomer include a copolymer in which the above-described acrylic monomer is copolymerized with a urethane structure or an epoxy structure.

  The resin composition preferably contains a solvent. Examples of the solvent include esters such as ethyl acetate, butyl acetate and propyl acetate; ketones such as methyl ethyl ketone, methyl isobutyl, dibutyl ketone and cyclohexanone; and organic solvents such as aromatics and hydrocarbons such as toluene, xylene and hexane. No.

  It is preferable that the resin composition further contains a polymerization initiator. Examples of the polymerization initiator include the above-described polymerization initiators. Especially, it is preferable that a photopolymerization initiator is contained in the resin composition.

  In the step of forming the resin layer, the resin composition is applied on the surface of the adhesive layer formed on at least one surface of the fiber layer. As a coating machine that can be used in the coating step, for example, a bar coater, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, or the like can be used.

  After applying the resin composition, it is preferable to heat at 70 ° C. to 200 ° C. for 0.1 hour to 1 hour in order to volatilize the solvent. In the heating step, for example, a method of drying by heating with hot air, infrared rays, far infrared rays or near infrared rays (heating drying method), or a method of drying under vacuum (vacuum drying method) can be adopted.

After evaporating the solvent, it is preferable to provide a step of curing the resin composition. Here, it is preferable to polymerize and cure by irradiation of radiation.
The amount of radiation to be irradiated is arbitrary as long as the photopolymerization initiator generates a radical. Specifically, it is preferable to irradiate ultraviolet rays having a wavelength of 300 nm to 450 nm in a range of 10 mJ / cm ^{2 to} 1000 mJ / cm ² . It is also preferable to irradiate radiation twice or more. Specific examples of the lamp used for irradiation include a metal halide lamp, a high-pressure mercury lamp, an ultraviolet LED lamp, and an electrodeless mercury lamp.

  In the step of curing the resin composition, photopolymerization and thermal polymerization may be performed simultaneously. In this case, the resin composition is heated at a temperature of 70 ° C. or more and 200 ° C. or less at the same time as irradiation with radiation to cure the resin composition.

(Application)
Since the laminate of the present invention has excellent optical characteristics, it can be used as a display element, a lighting element, a solar cell or a window material, or a panel or a substrate therefor.
More specifically, the laminate can be used 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.

  Further, the laminate can be used as a substrate for solar cells such as a silicon-based solar cell and a dye-sensitized solar cell. For use as a substrate, a barrier film, ITO, TFT, or the like may be laminated.

  Further, the laminate of the present invention is used for automobiles, railway vehicles, aircraft materials such as window materials, glazing, interior materials, outer panels, bumpers, etc. of automobiles, railway vehicles, aircraft, houses, office buildings, factories, etc., and personal computer housings. It can also be used as a structural material with home electric parts, packaging materials, building materials, civil engineering materials, marine products, and other industrial materials. As the window material, a film such as a fluorine film or a hard coat film or a material having impact resistance and light resistance may be laminated as necessary.

  Hereinafter, features of the present invention will be described more specifically with reference to examples and comparative examples. Materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples described below.

<Example 1>
[Preparation of phosphorylation reagent]
265 g of sodium dihydrogen phosphate dihydrate and 197 g of disodium hydrogen phosphate were dissolved in 538 g of water to obtain an aqueous solution of a phosphate compound (hereinafter, referred to as “phosphorylation reagent”).

[Phosphorylation]
Softwood bleached kraft pulp (manufactured by Oji Holdings Co., Ltd., water content 50% by mass, Canadian standard freeness (CSF) 700 ml measured according to JIS P 8121) is diluted with ion-exchanged water to a water content of 80% by mass. Thus, a pulp suspension was obtained. To the 500 g of the pulp suspension, 210 g of a phosphorylating reagent was added, and the mixture was occasionally kneaded with a blow dryer at 105 ° C. (manufactured by Yamato Scientific Co., Ltd., DKM400) until the mass became constant and dried. Subsequently, the mixture was heated for 1 hour while occasionally kneading with a blow dryer at 150 ° C. to introduce a phosphate group into the cellulose. At this time, the introduced amount of the phosphate group was 0.98 mmol / g.

  The amount of phosphate groups introduced was measured by diluting cellulose with ion-exchanged water to a content of 0.2% by mass, treating with an ion-exchange resin, and titrating with an alkali. In the treatment with the ion-exchange resin, 1/10 by volume of a strongly acidic ion-exchange resin (manufactured by Organo Co., Ltd., Amberjet 1024: conditioned) is added to the slurry containing 0.2% by mass of cellulose, followed by shaking for 1 hour. went. Thereafter, the mixture was poured onto a mesh having openings of 90 μm to separate the resin and the slurry. In the titration using an alkali, a change in the electric conductivity value of the slurry was measured while adding a 0.1 N aqueous sodium hydroxide solution to the slurry containing fibrous cellulose after ion exchange. That is, the amount of alkali (mmol) required in the first region of the curve shown in FIG. 4 was divided by the solid content (g) in the slurry to be titrated to obtain a substituent introduction amount (mmol / g).

[Alkali treatment, washing]
Next, 5000 ml of ion-exchanged water was added to the cellulose into which the phosphate group had been introduced. The pulp after dehydration was diluted with 5000 ml of ion-exchanged water, and a 1N aqueous sodium hydroxide solution was added little by little until the pH became 12 or more and 13 or less while stirring to obtain a pulp dispersion liquid. Thereafter, the pulp dispersion was dehydrated and washed by adding 5000 ml of ion-exchanged water. This dehydration washing was repeated once more.

[Machine processing]
Ion-exchanged water was added to the pulp obtained after the washing and dehydration to obtain a pulp dispersion having a solid content of 1.0% by mass. This pulp dispersion was treated using a high-pressure homogenizer (Panda Plus 2000, manufactured by NiroSoavi) to obtain a cellulose dispersion. In the treatment using the high-pressure homogenizer, it was passed through the homogenizing chamber 5 times at an operating pressure of 1200 bar. Further, this cellulose dispersion was treated using a wet atomizer (Ultimizer, manufactured by Sugino Machine Co., Ltd.) to obtain a fine fibrous cellulose dispersion. In the treatment using the wet atomization device, the mixture was passed through the treatment chamber five times at a pressure of 245 MPa. The average fiber width of the fine fibrous cellulose contained in the fine fibrous cellulose dispersion was 4 nm.

[Sheet]
The concentration was adjusted so that the solid content concentration of the fine fibrous cellulose dispersion was 0.5% by mass. Then, 20 parts by mass of a 0.5% by mass aqueous solution of polyethylene oxide (PEO-18, manufactured by Sumitomo Seika) was added to 100 parts by mass of the fine fibrous cellulose dispersion. Next, the dispersion was weighed so that the finished basis weight of the sheet became 45.0 g / m ² , spread on a commercially available acrylic plate, and dried in a thermo-hygrostat at 35 ° C. and a relative humidity of 15%. In addition, a metal frame for damming (a metal frame having an inner size of 180 mm × 180 mm) was arranged on the acrylic plate so as to have a predetermined basis weight. By the above procedure, a fine fibrous cellulose-containing sheet (fiber layer) was obtained. The thickness of the fine fibrous cellulose-containing sheet measured by a stylus thickness gauge (Millitron 1202D, manufactured by Marl) is 29.8 μm, and the density calculated by dividing the grammage by the thickness is 1.51 g / cm ^3. Met.

[Lamination of adhesive layer]
100 parts by mass of an acrylic resin grafted with an acryloyl group (Acryt 8KX-012C, manufactured by Taisei Fine Chemical Co., Ltd.), 38 parts by mass of a polyisocyanate compound (TPA-100, manufactured by Asahi Kasei Chemicals Corporation), a radical polymerization initiator (manufactured by BASF, 2 parts by mass of Irgacure 184) were mixed to obtain an adhesive composition. Next, the adhesive composition was applied to one surface of the fine fibrous cellulose-containing sheet using a bar coater, and then heated and cured at 100 ° C. for 1 hour to laminate an adhesive layer. Further, an adhesive layer was laminated on the other surface of the fine fibrous cellulose-containing sheet in the same manner. The thickness of the adhesive layer was 5 μm on one side. According to the above procedure, an adhesive layer laminated sheet (A) in which an adhesive layer was laminated on both surfaces of the fine fibrous cellulose-containing sheet was obtained.

[Lamination of resin layer]
A resin composition was obtained by mixing 100 parts by mass of a urethane acrylic resin (Beam Set 575CB, manufactured by Arakawa Chemical Industries, Ltd.) containing 5% by mass of 1-hydroxycyclohexylphenyl ketone as a photopolymerization initiator and 100 parts by mass of methyl ethyl ketone. Next, the resin composition was applied to one surface of the adhesive layer laminated sheet (A) with a bar coater, and heated at 100 ° C. for 5 minutes to volatilize methyl ethyl ketone. Further, the resin composition was cured by irradiating it with ultraviolet rays of 500 mJ / cm ² using a UV conveyor device (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) to form a resin layer. Further, a resin layer was formed on the other surface of the adhesive layer laminated sheet (A) by the same procedure. The thickness of the resin layer was 10 μm on one side. According to the above procedure, a laminate in which resin layers were laminated on both surfaces of the adhesive layer laminated sheet (A) was obtained.

<Example 2>
[Lamination of resin layer]
100 parts by mass of an acrylic resin containing pentaerythritol tetraacrylate as a main component (manufactured by Arakawa Chemical Industries, beam set 710), 100 parts by mass of methyl ethyl ketone, and 5 parts by mass of a radical polymerization initiator (IRGACURE 184, manufactured by BASF) are mixed. A resin composition was obtained. Next, the resin composition was applied to one surface of the adhesive layer laminated sheet (A) obtained in Example 1 with a bar coater, and heated at 100 ° C. for 5 minutes to volatilize methyl ethyl ketone. Further, the resin composition was cured by irradiating it with ultraviolet rays of 500 mJ / cm ² using a UV conveyor device (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) to form a resin layer. Further, a resin layer was formed on the other surface of the adhesive layer laminated sheet (A) by the same procedure. The thickness of the resin layer was 10 μm on one side. According to the above procedure, a laminate in which resin layers were laminated on both surfaces of the adhesive layer laminated sheet (A) was obtained.

<Example 3>
[Lamination of resin layer]
100 parts by mass of an acrylic resin containing dipentaerythritol hexaacrylate as a main component (manufactured by Arakawa Chemical Industries, beam set 710), 100 parts by mass of methyl ethyl ketone, and 5 parts by mass of a radical polymerization initiator (IRGACURE 184, manufactured by BASF) are mixed. Thus, a resin composition was obtained. Next, the resin composition was applied to one surface of the adhesive layer laminated sheet (A) obtained in Example 1 with a bar coater, and heated at 100 ° C. for 5 minutes to volatilize methyl ethyl ketone. Further, the resin composition was cured by irradiating it with ultraviolet rays of 500 mJ / cm ² using a UV conveyor device (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) to form a resin layer. Further, a resin layer was formed on the other surface of the adhesive layer laminated sheet (A) by the same procedure. The thickness of the resin layer was 10 μm on one side. According to the above procedure, a laminate in which resin layers were laminated on both surfaces of the adhesive layer laminated sheet (A) was obtained.

<Example 4>
[Preparation of glass cell for resin layer molding]
Two pieces of the adhesive layer laminated sheet (A) obtained in Example 1 were cut into a size of 120 mm in length and 55 mm in width. Next, a spacer having a length of 95 mm, a width of 40 mm, and a thickness of 2 mm was provided in the center of a silicone rubber having a length of 125 mm, a width of 60 mm, and a thickness of 2 mm to serve as a spacer. The adhesive layer laminated sheet (A) was inserted along the inner peripheral edge of the silicone rubber. In addition, an opening having a width of 5 mm for injecting a resin composition to be described later into the gap was provided on the side of the silicone rubber and the adhesive layer laminated sheet (A) serving as a spacer. Further, two sheets of the adhesive layer laminated sheet (A) are sandwiched between two glass plates having a length of 125 mm, a width of 60 mm, and a thickness of 3 mm from above and below, and two points on each side and one point on each side are fixed with a double clip and sealed. did. FIG. 5 is a view of the glass cell 200 for forming a resin layer formed as described above as viewed from above, and is a schematic view of the glass cell for forming a resin layer with the upper glass plate removed. As shown in FIG. 5, in the glass cell 200 for forming a resin layer, an adhesive layer laminated sheet (A) 130, silicon rubber 120, and a glass plate 110 are disposed around an internal space.

[Formation of resin layer]
100 parts by mass of an acrylic resin containing 1,10-decanediol diacrylate as a main component (manufactured by Shin-Nakamura Chemical Co., Ltd., A-DOD-N) and 3 parts by mass of a radical polymerization initiator (manufactured by BASF, Irgacure 184) are mixed. Thus, a resin composition was obtained. Next, the resin composition was injected into the internal space of the glass cell 200 for forming a resin layer using a micropipette through the opening of the spacer. Furthermore, silicone rubber is inserted into the opening and sealed, and the resin composition is cured by irradiating it with UV light of 300 mJ / cm ² 20 times using a UV conveyor device (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.). I let it. Thereafter, the glass plate and the silicone rubber were removed to obtain a laminate in which a fine fibrous cellulose-containing sheet (fiber layer) was laminated on both surfaces of a resin layer having a thickness of 1920 μm via an adhesive layer.

<Comparative Example 1>
In Example 1, the adhesive layer was not laminated. Other procedures were the same as in Example 1 to obtain a laminate.

<Comparative Example 2>
In Example 2, the adhesive layer was not laminated. Other procedures were the same as in Example 2 to obtain a laminate.

<Comparative Example 3>
In Example 3, the adhesive layer was not laminated. Other procedures were the same as in Example 3 to obtain a laminate.

<Comparative Example 4>
[Lamination of adhesive layer]
An adhesive composition was prepared by mixing 76 parts by mass of a UV coating anchor agent (Arakawa Chemical Industries, Ltd., Aracoat AP2510) which is a polyester resin, 10 parts by mass of a curing agent (Arakawa Chemical Industries, Ltd., Aracoat CL2502) and 14 parts by mass of methyl ethyl ketone. Obtained. Next, after applying the above adhesive composition to one surface of the fine fibrous cellulose-containing sheet (fibrous layer) obtained in Example 1 with a bar coater, the adhesive composition is cured by heating at 100 ° C. for 3 minutes. The layers were stacked. Further, an adhesive layer was laminated on the other surface of the fine fibrous cellulose-containing sheet in the same manner. The thickness of the adhesive layer was 5 μm on one side. According to the above procedure, an adhesive layer laminated sheet (B) in which the adhesive layers were laminated on both surfaces of the fine fibrous cellulose-containing sheet was obtained.

[Lamination of resin layer]
A resin layer was laminated on the adhesive layer laminated sheet (B) in the same procedure as in Example 1 to obtain a laminate.

<Comparative Example 5>
A resin layer was laminated on the adhesive layer laminated sheet (B) obtained in Comparative Example 4 in the same procedure as in Example 2 to obtain a laminate.

<Comparative Example 6>
A resin layer was laminated on the adhesive layer laminated sheet (B) obtained in Comparative Example 4 in the same procedure as in Example 3 to obtain a laminate.

<Comparative Example 7>
[Lamination of adhesive layer]
An adhesive composition was obtained by mixing 26 parts by mass of a silsesquioxane-based resin (composeran SQ107, manufactured by Arakawa Chemical Industry Co., Ltd.), 14 parts by mass of a curing agent (HBSQ202, manufactured by Arakawa Chemical Industry Co., Ltd.), and 60 parts by mass of isopropyl alcohol. . Next, the adhesive composition was applied to one surface of the fine fibrous cellulose-containing sheet obtained in Example 1 with a bar coater, and then heated at 100 ° C. for 5 minutes to volatilize isopropyl alcohol. Further, an ultraviolet ray of 300 mJ / cm ² was irradiated using a UV conveyor device (ECS-4011GX, manufactured by Eye Graphics Co., Ltd.) to cure the adhesive composition and laminate the adhesive layer. Further, an adhesive layer was laminated on the other surface of the fine fibrous cellulose-containing sheet in the same manner. The thickness of the adhesive layer was 5 μm on one side. By the above procedure, an adhesive layer laminated sheet (C) in which the adhesive layers were laminated on both surfaces of the fine fibrous cellulose-containing sheet was obtained.

[Lamination of resin layer]
The resin layer was laminated on the adhesive layer laminated sheet (C) in the same procedure as in Example 1 to obtain a laminate.

<Comparative Example 8>
A resin layer was laminated on the adhesive layer laminated sheet (B) obtained in Comparative Example 7 in the same procedure as in Example 2 to obtain a laminate.

<Comparative Example 9>
A resin layer was laminated on the adhesive layer laminated sheet (B) obtained in Comparative Example 7 in the same procedure as in Example 3 to obtain a laminate.

<Evaluation>
The laminates obtained in Examples and Comparative Examples were measured by the following methods.

[Tensile modulus]
Based on JIS P 8113, the tensile modulus at a temperature of 23 ° C. and a relative humidity of 50% was measured using a tensile tester (L & W, Tensile Tester CODE SE-064).

[Total light transmittance]
The total light transmittance was measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory) according to JIS K7361.

[Initial adhesion]
According to JIS K 5400, 100 1 mm ² cross cuts were put on the surface of the laminate on the fiber layer side, a cellophane tape (manufactured by Nichiban Co., Ltd.) was stuck thereon, and pressed with a load of 1.5 kg / cm ^2. After that, it was peeled in the 90 ° direction. The adhesion between the resin layer and the fibrous layer (fine fibrous cellulose-containing sheet) was evaluated based on the number of peeled cells.

[Adhesion after accelerated test]
The laminate was placed in a thermo-hygrostat (KCL-2000, manufactured by Tokyo Rika Instruments) having a temperature of 85 ° C. and a relative humidity of 85%, and was allowed to stand for 240 hours. Thereafter, the laminate was placed in an environment at a temperature of 23 ° C. and a relative humidity of 50% for one hour. Thereafter, 100 crosscuts of 1 mm ² were put on the surface of the laminate on the fiber layer side according to JIS K 5400, and a cellophane tape (manufactured by Nichiban Co., Ltd.) was stuck thereon, and a load of 1.5 kg / cm ² was applied. And then peeled in the 90 ° direction. The adhesion between the resin layer and the fibrous layer (fine fibrous cellulose-containing sheet) was evaluated based on the number of peeled cells.

As is clear from Table 1, in Examples 1 to 4 in which the adhesive layer contains an acryloyl group as a functional group forming a covalent bond with a (meth) acryloyl group and an isocyanate group as a functional group forming a covalent bond with a hydroxyl group. Thus, a laminate having high tensile elastic modulus, high total light transmittance, and good initial adhesion and adhesion after the acceleration test was obtained. This is because covalent bonds are formed between the isocyanate group of the adhesive layer and the hydroxyl group of the fine fibrous cellulose-containing sheet, and between the acryloyl group of the adhesive layer and the acryloyl group of the resin layer, respectively. It is considered that a strong adhesion was obtained because a covalent bond was also formed between the acryloyl group and the acryloyl group of the adhesive layer.
On the other hand, in Comparative Examples 1 to 3 in which no adhesive layer was laminated, both the initial adhesiveness and the adhesiveness after the accelerated test were low. In Comparative Examples 4 to 6 using a polyester resin as the adhesive layer and Comparative Examples 7 to 9 using a silsesquioxane-based resin, although the initial adhesion was relatively good, the adhesion after the accelerated test was good. Is insufficient, and practical use is concerned in applications where use under severe conditions is assumed.

(Production example)
<Example 5 (Production example 1 of inorganic film laminate)>
Using the laminates obtained in Examples 1 to 4, an inorganic film laminate can be produced by the following procedure.
An aluminum oxide film is formed on the stacked body by using an atomic layer deposition apparatus (SUNALE R-100B, manufactured by Picosun). Trimethylaluminum (TMA) is used as an aluminum raw material, and H ₂ O is used for the oxidation of TMA. The chamber temperature is set to 150 ° C., the pulse time of TMA is 0.1 second, the purge time is 4 seconds, the pulse time of H ₂ O is 0.1 second, and the purge time is 4 seconds. By repeating this cycle for 405 cycles, an inorganic film laminate in which a 30-nm-thick aluminum oxide film is laminated on both surfaces of the laminate is obtained.

<Example 6 (Example 2 of manufacturing inorganic film laminate)>
Using the laminates obtained in Examples 1 to 4, an inorganic film laminate can be produced by the following procedure.
A silicon oxynitride film is formed on the laminate by a plasma CVD apparatus (ICP-CVD roll-to-roll apparatus, manufactured by Cellvac). The laminate is stuck on 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 is set to 50 ° C., and the inflow gas is silane, ammonia, oxygen, and nitrogen. A plasma discharge is generated to form a film for 45 minutes to obtain an inorganic film laminate in which a silicon oxynitride film having a thickness of 500 nm is laminated on one surface of the laminate. Further, by forming a film on the opposite surface in the same procedure, an inorganic film laminate in which a silicon oxynitride film having a thickness of 500 nm is laminated on both surfaces of the laminate can be obtained.

Reference Signs List 10 fibrous layer 20 adhesive layer 30 resin layer 100 laminated body 110 glass plate 120 silicon rubber 130 adhesive layer laminated sheet (A)
150 Opening 200 Glass cell for forming resin layer

Claims (14)

Having a fiber layer, an adhesive layer, and a resin layer in this order,
The fiber layer contains fine fibrous cellulose having a fiber width of 1000 nm or less,
The adhesive layer includes a functional group (A) that forms a covalent bond with a (meth) acryloyl group, and further includes a functional group (B) that forms a covalent bond with a hydroxyl group and a hydrolyzable group of the functional group (B). Including at least one selected,
The functional group (A) are (meth) acryloyl group, _{^{and, H 2 C = CR 2 -CH}} (-OH) - is at least one selected from the group represented by,
The functional group (B) is at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an alkoxysilyl group, a silanol group, and an oxazoline group;
The resin layer is a laminate including a polymer of an acrylic monomer.
(However, R ² represents a hydrogen atom or a methyl group)   The laminate according to claim 1, wherein the adhesive layer includes a polymer having the functional group (A) and a compound having the functional group (B). After leaving the laminated body at a temperature of 85 ° C. and a relative humidity of 85% for 240 hours, the number of peelings in 100 masses of the fiber layer is 10 or less when a cross-cut test according to JIS K 5400 is performed. Item 3. The laminate according to Item 1 or 2 . Laminate according to any one of claims 1 to 3 density of the fiber layer is 1.0 g / cm ³ or more. The laminate according to any one of claims 1 to 4 , having a tensile modulus of 5 GPa or more. The laminate according to any one of claims 1 to 5 , having a total light transmittance of 85% or more. The laminate according to any one of claims 1 to 6 , wherein the adhesive layer further includes a polymerization initiator. The laminate according to any one of claims 1 to 7 , wherein the resin layer further includes a polymerization initiator. The laminate according to any one of claims 1 to 8 , wherein the adhesive layer is a coating adhesive layer, and the resin layer is a coating resin layer. The adhesive layer is formed by applying a composition containing the functional group (A) and a resin having a hydroxyl group, and a compound having at least two functional groups (B) on at least one surface of the fiber layer. The laminate according to any one of claims 1 to 9 , wherein the laminate is formed by forming and applying a resin composition containing an acrylic monomer onto the adhesive layer to form the resin layer. A step of obtaining a fiber layer containing fine fibrous cellulose having a fiber width of 1000 nm or less;
A composition comprising a functional group (A) forming a covalent bond with a (meth) acryloyl group and a functional group (B) forming a covalent bond with a hydroxyl group is applied to at least one surface of the fiber layer, and an adhesive layer is formed. Forming a;
Applying a resin composition containing an acrylic monomer, and forming a resin layer, a method for producing a laminate comprising :
The functional group (A) are (meth) acryloyl group, _{^{and, H 2 C = CR 2 -CH}} (-OH) - is at least one selected from the group represented by,
The method for producing a laminate, wherein the functional group (B) is at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an alkoxysilyl group, a silanol group, and an oxazoline group.
(However, R ² represents a hydrogen atom or a methyl group) The functional group (A) and composition said containing functional group (B), the functional group (A) and a resin having a hydroxyl group, according to claim 11, wherein the functional group (B) and a compound having at least two The method for producing a laminate according to the above. The method for producing a laminate according to claim 11, wherein the composition containing the functional group (A) and the functional group (B) further includes a polymerization initiator. The method for producing a laminate according to any one of claims 11 to 13 , wherein the resin composition further includes a polymerization initiator.

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