JP6907601B2 - Laminated sheet - Google Patents

Description

The present invention relates to a laminated sheet. Specifically, the present invention relates to a laminated sheet containing fine fibrous cellulose.

In recent years, due to the substitution of petroleum resources and heightened environmental awareness, materials using reproducible natural fibers have been attracting attention. 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 paper products.

As the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Then, a sheet composed of such fine fibrous cellulose and a composite sheet containing a fine fibrous cellulose-containing sheet and a resin layer have been developed. As the composite sheet, a sheet obtained by dispersing and curing fine fibrous cellulose in a resin composition and a sheet obtained by impregnating a fine fibrous cellulose sheet with a resin component are known. Further, a laminated sheet obtained by laminating a resin sheet and a fine fibrous cellulose sheet is also known.

In a sheet containing fine fibrous cellulose as described above, it has been studied to exhibit desired properties by forming an uneven shape on the sheet surface or the laminated surface of the sheet. For example, Patent Document 1 describes cellulose nano having a base material having a groove-shaped pattern and a cellulose nanofiber layer formed by applying a coating liquid containing cellulose nanofibers to a surface on which the groove shape is formed. Fiber laminates are disclosed. In the cellulose nanofiber laminate of Patent Document 1, the interface between the base material and the cellulose nanofiber layer is formed to have an uneven shape, and by adopting such a structure, the laminate has excellent gas barrier properties. Is being considered for manufacture.

Since the fine fibrous cellulose sheet has excellent transparency, its application to an optical sheet is also being studied. For example, Patent Document 2 discloses an optical film containing a transparent film and a hard coat layer having an uneven structure on the surface, and the hard coat layer contains a curable resin precursor and cellulose nanofibers. Further, Patent Document 3 discloses an organic EL device in which a curable resin layer, a transparent conductive layer, an organic layer and a metal electrode layer are laminated on a transparent substrate. In the organic EL device disclosed in Patent Document 3, the transparent substrate contains cellulose nanofibers, and a concavo-convex pattern shape is formed on the opposite surface of the curable resin layer in contact with the transparent substrate.

Japanese Unexamined Patent Publication No. 2014-65233 Japanese Unexamined Patent Publication No. 2014-92551 Japanese Unexamined Patent Publication No. 2012-28307

A sheet containing fine fibrous cellulose and having an uneven shape on the surface is expected to be applied to various uses, and depending on the use, tensile resistance may be required. Further, when the concave-convex-shaped recess becomes a groove, it may be required that the groove functions well as a flow path.
Therefore, in order to solve the problems of the prior art, the present inventors have made a fine fibrous cellulose-containing sheet having an uneven shape on the surface, which has both tensile resistance and flow path functionality. We proceeded with the study for the purpose of providing the containing sheet.

As a result of diligent studies to solve the above problems, the present inventors have found that a laminated sheet having a fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a first resin layer has a first layer. It has been found that by forming an intermittent portion in the resin layer, a laminated sheet having both tensile resistance and flow path functionality can be obtained.
Specifically, the present invention has the following configuration.

[1] A laminated layer comprising a fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a first resin layer on at least one surface of the fiber layer, and the first resin layer is partially provided with an intermittent portion. Sheet.
[2] The laminated sheet according to [1], wherein the intermittent portion is a groove portion, and a part of the constituent surface of the groove portion includes an exposed surface of the fiber layer.
[3] The laminated sheet according to [2], wherein the maximum width of the groove is 1 μm or more and 10 mm or less.
[4] The laminated sheet according to [2] or [3], wherein when the maximum width of the groove is W and the depth of the groove is T, the value represented by W / T is 0.1 or more and 1000 or less. ..
[5] The laminated sheet according to any one of [2] to [4], wherein the groove portion is a flow path for flowing a fluid.
[6] The laminated sheet according to any one of [1] to [5], wherein the first resin layer contains a hydrophobic resin.
[7] One of [1] to [6] having a second resin layer further on one surface of the fiber layer and on the surface opposite to the surface on which the first resin layer is provided. The laminated sheet described.
[8] The laminated sheet according to any one of [1] to [7], which has a tensile strength of 65 MPa or more.

According to the present invention, it is possible to obtain a laminated sheet having both tensile resistance and flow path functionality.

FIG. 1 is a cross-sectional view of an embodiment of the laminated sheet of the present invention. FIG. 2 is a plan view illustrating the form of the intermittent portion of the laminated sheet of the present invention. FIG. 3 is a cross-sectional view illustrating the cross-sectional shape of the intermittent portion of the laminated sheet of the present invention. FIG. 4 is a graph showing the relationship between the amount of NaOH added dropwise to the fiber raw material having a phosphoric acid group and the electrical conductivity. FIG. 5 is a graph showing the relationship between the amount of NaOH added to the fiber raw material having a carboxyl group and the electrical conductivity. FIG. 6 is a cross-sectional view of an embodiment of the laminated sheet of the present invention.

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

(Laminated sheet)
The present invention relates to a laminated sheet comprising a fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a first resin layer on at least one surface of the fiber layer. In the laminated sheet of the present invention, the first resin layer has an intermittent portion in a part thereof.

FIG. 1 is a cross-sectional view illustrating the configuration of the laminated sheet of the present invention. As shown in FIG. 1, the laminated sheet 10 has a structure in which the first resin layer 14 is laminated on the fiber layer 12. The first resin layer 14 has an intermittent portion 20. In the present specification, the intermittent portion 20 included in the first resin layer 14 means a region in which a part of the first resin layer 14 is missing and the fiber layer 12 is exposed. In FIG. 1, a plurality of intermittent portions 20 are formed, but only one may be formed.

Since the laminated sheet of the present invention has the above structure, it has excellent tensile resistance and flow path functionality. Here, the tensile strength of the laminated sheet can be evaluated by measuring the tensile strength of the laminated sheet. Specifically, the laminated sheet is a test piece cut into a length of 7 cm and a width of 15 mm, and the tensile tester (manufactured by L & W, Tensile Tester CODE SE-) conforms to JIS P 8113 except that the distance between chucks is 50 mm. 064) is used to measure the tensile strength (unit: N / m) at a temperature of 23 ° C. and a relative humidity of 50%. The tensile strength is divided by the thickness of the test piece (the thickness of the entire laminated sheet measured in the region where the intermittent portion does not exist) to obtain the tensile strength (unit: MPa). When the first resin layer of the laminated sheet has a groove, when cutting out the test piece, the test piece is cut so that the extending direction of the groove and the length direction of the test piece are orthogonal to each other. The tensile strength of the laminated sheet measured in this way is preferably 50 MPa or more, more preferably 65 MPa or more, and even more preferably 80 MPa or more. The upper limit of the tensile strength of the laminated sheet is not particularly limited, but may be, for example, 500 MPa. In the laminated sheet of the present invention, since the first resin layer having an intermittent portion is formed on the fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less, the tensile strength is maintained at a high level.

The flow path functionality of the laminated sheet can be judged by whether or not the fluid flows smoothly through the intermittent portion (groove portion) of the laminated sheet. Specifically, when a fluid is dropped on one end region in the longitudinal direction of the intermittent portion (groove portion) and the laminated sheet is tilted by 20 ° so that the end region is upward, the intermittent portion (groove portion) It is preferred that the fluid reach the other end region in the longitudinal direction. At this time, it is more preferable that the diffusion of the fluid stays only in the intermittent portion (groove portion) and the region around the intermittent portion (groove portion), and further preferably stays only in the intermittent portion (groove portion). Further, it is preferable that the diffusion in the thickness direction is small, and it is preferable that the fluid does not reach the back surface of the fiber layer of the laminated sheet. As the fluid used for evaluating the flow path functionality of the sheet, for example, an organic solvent such as isopropyl alcohol can be used.

Since the laminated sheet of the present invention has a fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less, it is also characterized in that the formability (dimensional stability) of the groove formed in the first resin layer is good. be. In the present invention, since the fiber layer functions to suppress the distortion of the first resin layer, it is possible to effectively suppress the distortion of the size of the groove formed in the first resin layer.

In the present invention, the intermittent portion 20 is preferably a groove portion. Even when the intermittent portion 20 is a groove portion, a part of the constituent surface of the groove portion includes an exposed surface of the fiber layer 12. In the present invention, the shape of the groove is not particularly limited, but it is preferable that the groove extends in one direction on the surface of the laminated sheet. For example, FIG. 2A shows a plan view of a laminated sheet in which one groove is formed in the first resin layer 14. Here, the widths of the grooves are substantially the same in the longitudinal direction. Further, a plurality of grooves may be formed, and for example, it may have a form as shown in FIG. 2 (b). Further, one end and the other end of the groove may coincide with the end face of the laminated sheet, or may exist inside the end face of the laminated sheet.

Further, as shown in FIG. 2C, the groove portion may have a structure in which the width of the groove portion narrows from one end to the other end in the longitudinal direction of the groove portion, as shown in FIG. 2D. In addition, a meandering groove structure can also be adopted. It is also possible to adopt a structure in which two or more grooves meet at one place or a structure in which they intersect.

In order to further improve the flowability of the fluid, the groove portion can be provided with an inclination. For example, by giving a gradient to the thickness of the fiber layer 12, the groove portion may be inclined in the longitudinal direction.

The cross-sectional shape of the groove in the thickness direction is not particularly limited, and may be a shape in which the periphery is surrounded by two side surfaces and a bottom surface, or a shape in which the periphery is surrounded by a series of curved surfaces. .. For example, FIG. 3A shows an example in which the cross-sectional shape of the groove portion in the thickness direction is a shape (square shape) surrounded by two side surfaces and a bottom surface. In FIG. 3A, the two side surfaces forming the groove portion are the exposed side surfaces of the first resin layer 14, and the bottom surface connecting the two side surfaces is the exposed surface of the fiber layer 12. Further, FIG. 3B exemplifies a groove portion having a shape surrounded by a curved surface. In such a case, a part of the curved surface is formed by the exposed surface of the fiber layer 12, or a part between the curved surface is formed by the exposed surface of the fiber layer 12. In FIG. 3C, a ∨-shaped groove portion surrounded by two side surfaces is formed. In this case, the bottom surface is not formed in the groove, but since the top of the ∨-shaped shape reaches the fiber layer 12, it can be said that a part of the constituent surface of the groove includes the exposed surface of the fiber layer 12. ..

The maximum width of the groove can be appropriately adjusted depending on the application of the laminated sheet, but for example, it is preferably 1 μm or more and 10 mm or less, more preferably 5 μm or more and 5 mm or less, and 5 μm or more and 2 mm or less. More preferred. Here, the maximum width of the groove portion is the width indicated by W in FIGS. 3A to 3C, and is the maximum width in the cross-sectional view in the thickness direction of the groove portion. When measuring the maximum width of the groove, observe the cross section of the laminated sheet in the thickness direction of the groove with an optical microscope, measure the maximum width of the groove at any 10 points, calculate the average value, and calculate the maximum width of the groove. And.

When the maximum width of the groove is W and the depth of the groove is T, the value represented by W / T is preferably 0.1 or more and 1000 or less, and preferably 0.1 or more and 500 or less. More preferably, it is 0.2 or more and 250 or less. The value represented by W / T can also be said to be the aspect ratio of the cross-sectional shape in the thickness direction of the groove portion. By setting the value represented by W / T within the above range, it is possible to improve the flow when the fluid flows through the groove. The depth T of the groove is the thickness of the first resin layer constituting the groove.

As described above, since the groove can allow the fluid to flow down, it is preferable to use the groove as a flow path for flowing the fluid. That is, the laminated sheet of the present invention is preferably a flow path-containing laminated sheet.

(Fiber layer)
The fiber layer is a layer containing fibrous cellulose having a fiber width of 1000 nm or less. In the present specification, fibrous cellulose having a fiber width of 1000 nm or less is also referred to as fine fibrous cellulose.

In the present invention, the content of fibrous cellulose (fine fibrous cellulose) having a fiber width of 1000 nm or less contained in the fiber layer is preferably 60% by mass or more with respect to the total mass of the fiber layer, and is 70. It is more preferably mass% or more, and even more preferably 80% by mass or more. Further, the content of the fine fibrous cellulose contained in the fiber layer may be 100% by mass.

The thickness of the fiber layer is preferably 5 μm or more, more preferably 10 μm or more, further preferably 20 μm or more, and even more preferably 30 μm or more. The upper limit of the thickness of the fiber layer is not particularly limited, but is preferably 500 μm, for example.

The fibrous layer may further contain other optional components in addition to the fine fibrous cellulose. As the optional component, for example, an oxygen-containing organic compound (however, the above-mentioned cellulose fiber is excluded) can be mentioned. The oxygen-containing organic compound is preferably a hydrophilic organic compound. Hydrophilic oxygen-containing organic compounds can improve the strength, density, chemical resistance, etc. of the fiber layer.

Examples of oxygen-containing organic compounds include polyethylene glycol, polyethylene oxide, casein, dextrin, starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), polyethylene oxide, polyvinylpyrrolidone, polyvinylmethyl ether, and poly. Hydrophilic polymers such as acrylates, polyacrylamides, acrylic acid alkyl ester copolymers, urethane copolymers, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.); hydrophilicity such as glycerin, sorbitol, ethylene glycol, etc. Small sex molecules can be mentioned. Among these, polyethylene glycol, polyethylene oxide, glycerin, sorbitol, and polyvinyl alcohol are preferable, and at least one selected from polyethylene glycol, polyvinyl alcohol, and polyethylene oxide is preferable from the viewpoint of improving the strength, density, chemical resistance, and the like of the fiber layer. More preferably it is a seed.

The oxygen-containing organic compound is preferably an organic compound polymer having a molecular weight of 50,000 or more and 8 million or less. The molecular weight of the oxygen-containing organic compound is preferably 100,000 or more and 5 million or less, but for example, it may be a low molecular weight having a molecular weight of less than 1000.

Moreover, as an optional component, an organic ion can also be mentioned. Examples of the organic ion include tetraalkylammonium ion and tetraalkylphosphonium ion. Examples of the tetraalkylammonium ion include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, tetraheptylammonium ion, tributylmethylammonium ion, and lauryltrimethyl. Examples thereof include ammonium ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, octyldimethylethylammonium ion, lauryldimethylethylammonium ion, didecyldimethylammonium ion, lauryldimethylbenzylammonium ion and tributylbenzylammonium ion. Examples of the tetraalkylphosphonium ion include tetramethylphosphonium ion, tetraethylphosphonium ion, tetrapropylphosphonium ion, tetrabutylphosphonium ion, and lauryltrimethylphosphonium ion. Further, examples of the tetrapropyl onium ion and the tetrabutyl onium ion include tetra n-propyl onium ion and tetra n-butyl onium ion, respectively.

Further, the fiber layer has optional components such as a coupling agent, an inorganic layered compound, an inorganic compound, a leveling agent, a defoaming agent, an organic particle, a lubricant, an antistatic agent, an ultraviolet protective agent, a dye, a pigment, a stabilizer, and magnetism. It may contain a powder, an orientation accelerator, a plasticizing agent, a cross-linking agent and the like.

The content of the optional component contained in the fiber layer is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and 20 parts by mass with respect to 100 parts by mass of the fine fibrous cellulose contained in the fiber layer. It is more preferably parts by mass or less. By setting the content of the optional component within the above range, a laminated sheet having high transparency and strength can be formed.

<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. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen bleached craft. Examples thereof include chemical pulp such as pulp (OKP). Further, semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), mechanical pulp such as crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP) and the like can be mentioned, but are 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, and cellulose, chitin and chitosan isolated from sea squirts and seaweed, but are not particularly limited. .. Examples of the deinked pulp include deinked pulp made from used paper, but the deinking pulp is not particularly limited. As the pulp of the present embodiment, one of the above types may be used alone, or two or more types may be mixed and used. Among the above pulps, wood pulp containing cellulose and deinked pulp are preferable in terms of availability. Among wood pulps, chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber refining (defibration) is high, the decomposition of cellulose in the pulp is small, and the fine fibers with a large axial ratio are fine. It is preferable in that fibrous cellulose can be obtained. Of these, kraft pulp and sulfite pulp are most preferably selected.

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. If the average fiber width of the fine fibrous cellulose is less than 2 nm, it is dissolved in water as a cellulose molecule, so that the physical properties (strength, rigidity, dimensional stability) of the fine fibrous cellulose tend to be difficult to develop. .. The fine fibrous cellulose is, for example, a monofibrous cellulose having a fiber width of 1000 nm or less.

The fiber width of the fine fibrous cellulose is measured by electron microscope observation 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 hydrophilized carbon film-coated grid to form a sample for TEM observation. do. If it contains wide fibers, an SEM image of the surface cast on the glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, or 50,000 times depending on the width of the constituent fibers. However, the sample, observation conditions and magnification should be adjusted so as to satisfy the following conditions.

(1) A 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 that intersects the straight line perpendicularly is drawn in the same image, and 20 or more fibers intersect the straight line Y.

The width of the fiber intersecting the straight line X and the straight line Y is visually read with respect to the observation image satisfying the above conditions. In this way, at least three sets of images of the non-overlapping surface portions are observed, and the widths of the fibers intersecting the straight lines X and Y are read for each image. In this way, at least 20 fibers × 2 × 3 = 120 fibers are read. The average fiber width of the fine fibrous cellulose is the average value of the fiber widths read in this way.

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, the destruction of the crystal region of the fine fibrous cellulose can be suppressed, and the slurry viscosity of the fine fibrous cellulose can be set within an appropriate range. The fiber length of the fine fibrous cellulose can be obtained by image analysis by TEM, SEM, or 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 the diffraction profile obtained from the wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418 Å) monochromatic with graphite. Specifically, it can be identified by having typical peaks at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less.
The ratio of the type I crystal structure to the fine fibrous cellulose is preferably 30% or more, more preferably 50% or more, still more preferably 70% or more. In this case, further excellent performance can be expected in terms of heat resistance and low coefficient of linear thermal expansion. The crystallinity is determined by a conventional method from the X-ray diffraction profile measured and the pattern (Seagal et al., Textile Research Journal, Vol. 29, p. 786, 1959).

The fine fibrous cellulose preferably has an ionic functional group. The ionic functional group is preferably an anionic group, and examples of such an ionic functional group include a phosphate group, a substituent derived from the phosphate group (sometimes simply referred to as a phosphate group), and a carboxyl group. Alternatively, it may be at least one selected from a substituent derived from a carboxyl group (sometimes simply referred to as a carboxyl group) and a sulfone group or a substituent derived from a sulfone group (sometimes simply referred to as a sulfon group). It is more preferably at least one selected from a phosphoric acid group and a carboxyl group, and particularly preferably a phosphoric acid group.

The phosphoric acid group is a divalent functional group obtained by removing the hydroxyl group from phosphoric acid. Specifically, it is a group represented by _{−PO 3} H _2. Substituents derived from phosphate groups include substituents such as polycondensation groups of phosphate groups, salts of phosphate groups, and phosphate ester groups, and even if they are ionic substituents, they are nonionic substituents. It may be a group.

In the present invention, the phosphoric acid group or the substituent derived from the phosphoric acid group may be a substituent represented by the following formula (1).

In equation (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (an integer of n = 1 or more and n or less) and α'are independent of each other. Represents R or OR. R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group. , Aromatic groups, or inducing groups thereof; β is a monovalent or higher cation consisting of an organic or inorganic substance.

<Phosphate group introduction process>
In the phosphoric acid group introduction step, a fiber raw material containing cellulose is reacted with at least one selected from a compound having a phosphoric acid group and a salt thereof (hereinafter, referred to as “phosphorylation reagent” or “Compound A”). Can be done by. Such phosphorylation reagents may be mixed with the dry or wet fiber raw material in the form of powder or aqueous solution. As another example, a powder or an aqueous solution of a phosphorylation reagent may be added to the slurry of the fiber raw material.

The phosphoric acid group introduction step can be carried out by reacting a fiber raw material containing cellulose with at least one selected from a compound having a phosphoric acid group and a salt thereof (phosphorylation reagent or compound A). This reaction may be carried out in the presence of at least one selected from urea and its derivatives (hereinafter referred to as "Compound B").

An example of a method of allowing compound A to act on a fiber raw material in the coexistence of compound B includes a method of mixing a powder or an aqueous solution of compound A and compound B with a fiber raw material in a dry state or a wet state. Another example is a method of adding a powder or an aqueous solution of Compound A and Compound B to a slurry of a fiber raw material. Of these, since the reaction uniformity is high, a method of adding an aqueous solution of compound A and compound B to a dry fiber raw material, or adding a powder or aqueous solution of compound A and compound B to a wet fiber raw material. The method is preferred. Further, compound A and compound B may be added at the same time or separately. Alternatively, compound A and compound B to be tested in the reaction may be added as an aqueous solution first, and the excess chemical solution may be removed by squeezing. The form of the fiber raw material is preferably cotton-like or thin sheet-like, but is not particularly limited.

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

Of these, from the viewpoints of high efficiency of introduction of phosphoric acid group, easy improvement of defibration efficiency in the defibration step described later, low cost, and easy industrial application, phosphoric acid and phosphoric acid A sodium salt, a potassium salt of phosphoric acid, or an ammonium salt of phosphoric acid is preferable. Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferred.

Further, the compound A is preferably used as an aqueous solution because the uniformity of the reaction is enhanced and the efficiency of introducing the phosphoric acid group is increased. The pH of the aqueous solution of compound A is not particularly limited, but is preferably 7 or less because the efficiency of introducing a phosphoric acid group is high, and more preferably 3 or more and pH 7 or less from the viewpoint of suppressing hydrolysis of pulp fibers. The pH of the aqueous solution of the compound A may be adjusted, for example, by using a compound having a phosphoric acid group in combination with an acidic compound and an alkaline compound, 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 compound having a phosphoric acid group and showing acidity.

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 phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material (absolute dry mass) is 0.5% by mass or more and 100% by mass. The following is preferable, 1% by mass or more and 50% by mass or less is more preferable, and 2% by mass or more and 30% by mass or less is most preferable. When the amount of phosphorus atom added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. When the amount of the phosphorus atom added to the fiber raw material exceeds 100% by mass, the effect of improving the yield reaches a plateau and the cost of the compound A used increases. On the other hand, the yield can be increased by setting the addition amount of phosphorus atoms to the fiber raw material to be equal to or higher than the above lower limit value.

Examples of compound B used in this embodiment include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like.

Compound B is preferably used as an aqueous solution like compound A. Further, since the uniformity of the reaction is enhanced, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved. The amount of compound B added to the fiber raw material (absolute dry mass) is preferably 1% by mass or more and 500% by mass or less, more preferably 10% by mass or more and 400% by mass or less, and 100% by mass or more and 350% by mass or less. It is more preferably 150% by mass or more, and particularly preferably 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 amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine and the like. Among these, triethylamine in particular is known to act as a good reaction catalyst.

In the phosphoric acid group introduction step, it is preferable to perform heat treatment. The heat treatment temperature is preferably selected so that the phosphate group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. Specifically, it is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 150 ° C. or higher and 200 ° C. or lower. Further, a vacuum dryer, an infrared heating device, and a microwave heating device may be used for heating.

During the heat treatment, when the fiber raw material slurry containing the compound A contains water and the fiber raw material is allowed to stand for a long time, the water molecules and the dissolved compound A move to the surface of the fiber raw material as it dries. do. Therefore, the concentration of the compound A in the fiber raw material may be uneven, and the introduction of the phosphoric acid group to the fiber surface may not proceed uniformly. In order to suppress the occurrence of uneven concentration of compound A in the fiber raw material due to drying, a very thin sheet-shaped fiber raw material is used, or the fiber raw material and compound A are kneaded or stirred with a kneader or the like and dried by heating or under reduced pressure. You can take the method.

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 fibers such as phosphate groups to the hydroxyl groups to the outside of the device system. For example, a blower type oven. Etc. are preferable. If the water in the apparatus system is constantly discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphate esterification, can be suppressed, and the acid hydrolysis of the sugar chain in the fiber can also be suppressed. , Fine fibers with a high axial ratio can be obtained.

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

The content of the phosphoric acid group (the amount of the phosphoric acid group introduced) is preferably 0.10 mmol / g or more, and more preferably 0.20 mmol / g or more per 1 g (mass) of the fine fibrous cellulose. , 0.50 mmol / g or more, more preferably. The content of the phosphoric acid group is preferably 3.65 mmol / g or less, more preferably 3.50 mmol / g or less, and 3.00 mmol / g or less per 1 g (mass) of fine fibrous cellulose. Is more preferable. By setting the content of the phosphoric acid group within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous cellulose. In the present specification, the content of phosphoric acid groups (introduction amount of phosphoric acid groups) of the fine fibrous cellulose is equal to the amount of strong acid groups of the phosphoric acid groups of the fine fibrous cellulose, as will be described later.

The amount of the phosphoric acid group introduced into the fiber raw material can be measured by the conductivity titration method. Specifically, it is refined by a defibration treatment step, the obtained fine fibrous cellulose-containing slurry is treated with an ion exchange resin, and then the change in electrical conductivity is obtained while adding an aqueous sodium hydroxide solution. The amount introduced can be measured.

In the conductivity titration, the addition of alkali gives the curve shown in FIG. Initially, the electrical conductivity drops sharply (hereinafter referred to as the "first region"). After that, the conductivity begins to increase slightly (hereinafter referred to as "second region"). After that, the increment of conductivity increases (hereinafter referred to as "third region"). That is, three regions appear. The boundary point between the second region and the third region is defined by the point at which the second derivative value of the conductivity, that is, the amount of change in the increment (slope) of the conductivity is maximized. Of these, the amount of alkali required in the first region is equal to the amount of strong acid 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 phosphoric acid group causes condensation, the weakly acidic group is apparently lost, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When it is said, it means the amount of strongly acidic groups. 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 the amount of substituent introduced (mmol / g).

The phosphoric acid group introduction step may be performed at least once, but may be repeated a plurality of times. In this case, more phosphate groups are introduced, which is preferable.

<Carboxyl group introduction process>
In the present invention, when the fine fibrous cellulose has a carboxyl group, for example, the fiber raw material is subjected to an oxidation treatment such as a TEMPO oxidation treatment, or a compound having a group derived from a carboxylic acid, a derivative thereof, or an acid thereof. A carboxyl group can be introduced by treating with an anhydride or a derivative thereof.

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. Be done.

The acid anhydride of the compound having a carboxyl group is not particularly limited, and examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Be done.

The derivative of the compound having a carboxyl group is not particularly limited, and examples thereof include an imide of an acid anhydride of a compound having a carboxyl group and a derivative of an acid anhydride of a compound having a carboxyl group. The imide of the acid anhydride of the compound having a carboxyl group is not particularly limited, and examples thereof include an imide of a dicarboxylic acid compound such as maleimide, succinateimide, and phthalateimide.

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

The amount of the carboxyl group introduced is preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol / g or more per 1 g (mass) of the fine fibrous cellulose. Is even more preferable. The content of the carboxyl group is preferably 3.65 mmol / g or less, more preferably 3.50 mmol / g or less, and 3.00 mmol / g or less per 1 g (mass) of fine fibrous cellulose. It is more preferable to have.
The amount of the carboxyl group introduced into the fiber raw material can be measured by the conductivity titration method. In the conductivity titration, the addition of alkali gives the curve shown in FIG. The amount of alkali (mmol) required in the first region of the curve shown in FIG. 5 is divided by the solid content (g) in the slurry to be titrated to obtain the amount of substituent introduced (mmol / g).

<Alkaline treatment>
When producing fine fibrous cellulose, an alkali treatment may be performed between the ionic substituent introduction step such as the phosphate group introduction step and the carboxyl group introduction step and the defibration treatment step described later. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the ionic substituent-introduced fiber in an alkaline solution.
The alkaline compound contained in the alkaline solution is not particularly limited, but may be an inorganic alkaline compound or an organic alkaline 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.
Further, 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 alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower.
The immersion time in the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less.
The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, preferably 1000% by mass or more and 10000% by mass or less, based on the absolute dry mass of the ionic substituent-introduced fiber. More preferably.

In order to reduce the amount of the alkaline solution used in the alkaline treatment step, the ionic substituent-introduced fiber may be washed with water or an organic solvent before the alkaline treatment step. After the alkali treatment, in order to improve the handleability, it is preferable to wash the alkali-treated ionic substituent-introduced fiber with water or an organic solvent before the defibration treatment step.

<Fiber processing process>
The ionic substituent-introduced fiber is defibrated in the defibration treatment step. In the defibration treatment step, the fibers are usually defibrated using a defibration treatment device to obtain a fine fibrous cellulose-containing slurry, but the treatment device and the treatment method are not particularly limited.
As the defibration processing apparatus, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill and the like can be used. Alternatively, as the defibration processing device, a wet pulverizing 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 should be used. You can also. The defibration processing apparatus 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 crushed media and less likely to cause contamination.

At the time of the defibration treatment, it is preferable to dilute the fiber raw material alone or in combination with water and an organic solvent to form a slurry, but the fiber raw material is not particularly limited. As the dispersion medium, a polar organic solvent can be used in addition to water. Preferred polar organic solvents include, but are not limited to, alcohols, ketones, ethers, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butyl alcohol and the like. Examples of the ketones include acetone, methyl ethyl ketone (MEK) and the like. Examples of ethers include diethyl ether and tetrahydrofuran (THF). The dispersion medium may be one kind or two or more kinds. Further, the dispersion medium may contain a solid content other than the fiber raw material, for example, urea having a hydrogen bond property.

In the present invention, the defibration 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, a method of using a commonly used dehydrator, press, and dryer. In addition, known methods such as those described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used. Further, the concentrated fine fibrous cellulose may be made into a sheet. The sheet can also be crushed for defibration treatment.

Equipment used for crushing fine fibrous cellulose includes high-speed defibrator, grinder (stone mill type crusher), high-pressure homogenizer, ultra-high pressure homogenizer, high-pressure collision type crusher, ball mill, bead mill, disc type refiner, and conical. Wet pulverizers such as refiners, twin-screw kneaders, vibration mills, homomixers under high-speed rotation, ultrasonic dispersers, beaters, etc. can also be used, but are not particularly limited.

(First resin layer)
The laminated sheet of the present invention includes a first resin layer on at least one surface of the above-mentioned fiber layer, and the first resin layer has an intermittent portion.

Examples of the resin component constituting the first resin layer include acrylic resin, polycarbonate resin, polyvinyl alcohol resin, olefin resin, polyester resin, styrene resin, urethane resin, phenol resin, and fluorine resin. , Epoxy resin, polyamide resin, polyimide resin, silicon resin and the like. The resin component may be a copolymer of the monomers constituting the above-mentioned resin, or may be a mixture of the above-mentioned resins. Among them, the resin component constituting the first resin layer preferably contains a hydrophobic resin, and particularly preferably contains an acrylic resin. In this specification, the hydrophobic resin is defined as a resin having a contact angle with water of 60 degrees or more in a dry state. Here, "in a dry state" means excluding a state in which the hydrophobic resin has an affinity for water, such as when it is in an emulsion state.

Examples of the acrylic monomer constituting the acrylic resin include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol di (meth). Meta) acrylate, neopentyl glycol adipate di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, EO-modified phosphorus Acid di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethyl propanetri (meth) acrylate, ethylene oxide-modified trimethylol propanetri (meth) acrylate, diventaerythritol tri ( Meta) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, PO-modified trimethylolpropantri (meth) acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol tetraacrylate, ditri Methylolpropantetraacrylate, dipentaerythritol penta (meth) acrylate propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, 1,10-decane Examples thereof include diol diacrylate.

Further, as the acrylic monomer, it is also preferable to use a monofunctional alkyl (meth) acrylate in combination with the above-mentioned polyfunctional acrylic monomer. Examples of the monofunctional alkyl (meth) acrylate include pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, n-octyl (meth) acrylate, and 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 can be mentioned.

The first resin layer is preferably a thermosetting resin layer or an ultraviolet curable resin layer, and more preferably an ultraviolet curable resin layer. With such a configuration, one resin layer having an intermittent portion can be easily formed. Specifically, the first resin composition is applied to the entire surface of the fiber layer, the region other than the intermittent portion is cured by ultraviolet rays, and the uncured portion is removed to form the first resin layer having the intermittent portion. be able to.

When forming the first resin layer having an intermittent portion, the first resin composition is applied to the entire surface on the fiber layer, the entire surface is cured, and then the intermittent portion is formed by plasma etching processing. You may. In this case, the plasma etching process is preferably repeated until the exposure of the fiber layer is confirmed.

The thickness of the first resin layer is preferably 1 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, still more preferably 10 μm or more. The upper limit of the thickness of the first resin layer is not particularly limited, but is preferably 500 μm, for example.

The content of the resin component contained in the first resin layer is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and 90% by mass or more. Is more preferable.

The first resin layer may contain an arbitrary component. Optional components include, for example, an ultraviolet protective agent, a radical scavenger, a water-soluble polymer other than the resin component described above, a saccharide exemplified for pectin, a coupling agent, an inorganic compound, a leveling agent, a defoaming agent, and an organic system. Examples thereof include particles, lubricants, antistatic agents, stabilizers, magnetic powders, orientation promoters, plasticizers, cross-linking agents and the like.

(Second resin layer)
The laminated sheet of the present invention may further have a second resin layer on one surface of the fiber layer and on the surface opposite to the surface on which the first resin layer is provided. FIG. 6 is a cross-sectional view illustrating the configuration of the laminated sheet 10 in which the second resin layer 16 is laminated on one surface of the fiber layer 12. The second resin layer 16 is laminated on one surface of the fiber layer 12 and on the surface opposite to the surface on which the first resin layer 14 is provided. By providing the second resin layer 16 as shown in FIG. 6 on the fiber layer 12, the tensile resistance of the laminated sheet can be increased more effectively.

Examples of the resin component constituting the second resin layer include the same resin components as those of the first resin layer. The resin component constituting the first resin layer and the resin component constituting the second resin layer may be the same resin component or different resin components.

The thickness of the second resin layer is preferably 1 μm or more, more preferably 3 μm or more, further preferably 5 μm or more, and even more preferably 10 μm or more. The upper limit of the thickness of the second resin layer is not particularly limited, but is preferably 500 μm, for example.

The content of the resin component contained in each of the second resin layers is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and 90% by mass. The above is more preferable.

The second resin layer may contain an arbitrary component, and as an optional component. Examples of components similar to the optional components that can be contained in the first resin layer can be mentioned.

(Manufacturing method of laminated sheet)
The method for producing a laminated sheet of the present invention includes a step of obtaining a fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a step of forming a first resin layer having an intermittent portion on at least one surface of the fiber layer. And, including.

(Process to obtain fiber layer)
The step of obtaining the fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less includes a step of coating a fine fibrous cellulose-containing slurry on a substrate or a step of making a paper of the fine fibrous cellulose-containing slurry. Above all, the step of obtaining the fiber layer containing the fine fibrous cellulose preferably includes a step of coating the fine fibrous cellulose-containing slurry on the base material.

<Coating process>
In the coating step, a fine fibrous cellulose-containing slurry is applied onto a base material, and the fine fibrous cellulose-containing sheet formed by drying the slurry is peeled off from the base material to obtain a sheet (fiber layer). It is a process. By using a coating device and a long base material, sheets can be continuously produced. The concentration of the slurry to be coated is not particularly limited, but is preferably 0.05% by mass or more and 5% by mass or less.

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

In the coating process, when the viscosity of the fine fibrous cellulose-containing slurry is low and it develops on the base material, it is used for damming on the base material in order to obtain a fine fibrous cellulose-containing sheet having a predetermined thickness and basis weight. The frame may be fixed and used. The quality of the dammed frame is not particularly limited, but it is preferable to select one in which the end portion of the sheet that adheres after drying can be easily peeled off. Of these, those obtained by molding 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, metal plates such as aluminum plates, zinc plates, copper plates and iron plates, and those whose surfaces are oxidized, stainless steel. Molded plates, brass plates, etc. can be used.

As a coating machine for coating the fine fibrous cellulose-containing slurry, for example, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater and 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 20 ° C. or higher and 45 ° C. or lower, more preferably 25 ° C. or higher and 40 ° C. or lower, and further preferably 27 ° C. or higher and 35 ° C. or lower. When the coating temperature is at least the above lower limit value, the fine fibrous cellulose-containing slurry can be easily coated, and when it is at least the above upper limit value, volatilization of the dispersion medium during coating can be suppressed.

In the coating step, it is preferable to coat 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.} 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 fiber layer containing the fine fibrous cellulose preferably includes a step of drying the fine fibrous cellulose-containing slurry coated on the base material. The drying method is not particularly limited, but either a non-contact drying method or a method of drying while restraining the sheet may be used, or a combination of these may be used.

The non-contact drying method is not particularly limited, but a method of heating and drying with hot air, infrared rays, far infrared rays or near infrared rays (heat drying method) and a method of vacuum drying (vacuum drying method) are applied. Can be done. The heat drying method and the vacuum drying method may be combined, but the heat drying method is usually applied. Drying with infrared rays, far infrared rays or near infrared rays can be performed using an infrared device, a far infrared device or a near infrared device, but is not particularly limited. The heating temperature in the heat-drying method is not particularly limited, but is preferably 20 ° C. or higher and 120 ° C. or lower, and more preferably 25 ° C. or higher and 105 ° C. or lower. When the heating temperature is at least the above lower limit value, the dispersion medium can be rapidly volatilized, and when it is at least the above upper limit value, the cost required for heating can be suppressed and the discoloration of fine fibrous cellulose due to heat can be suppressed. ..

After drying, the obtained fine fibrous cellulose-containing sheet is peeled off from the base material. When the base material is a sheet, the fine fibrous cellulose-containing sheet and the base material are wound while being laminated to form fine fibers. The fine fibrous cellulose-containing sheet may be peeled off from the process substrate immediately before the use of the cellulose-containing sheet.

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

In the papermaking process, the fine fibrous cellulose-containing slurry is filtered on a wire and dehydrated to obtain a wet paper sheet, which is 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 the slurry is filtered and dehydrated, the filter cloth for filtration is not particularly limited, but it is important that the fine fibrous cellulose does not pass through and the filtration rate does not become too slow. Such a filter cloth is not particularly limited, but a sheet made of an organic polymer, a woven fabric, or a porous membrane is preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE) are preferable. Specific examples thereof include a porous membrane of polytetrafluoroethylene having a pore size of 0.1 μm or more and 20 μm or less, for example, 1 μm, polyethylene terephthalate having a pore size of 0.1 μm or more and 20 μm or less, for example, 1 μm, or a polyethylene woven fabric, but the present invention is not particularly limited.

The method for producing a sheet from the fine fibrous cellulose-containing slurry is not particularly limited, and examples thereof include a method using the production apparatus described in WO2011 / 013567. This manufacturing equipment discharges a slurry containing fine fibrous cellulose onto the upper surface of an endless belt, and squeezes a dispersion medium from the discharged slurry to generate a web, and a water-squeezed section that dries the web to produce a fiber sheet. It has a drying section to produce. An endless belt is arranged from the watering section to the drying section, and the web generated in the watering 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 examples thereof include a dehydration method that is usually used in the production of paper. A method of dehydrating with a long net, a circular net, an inclined wire, or the like and then dehydrating with a roll press. Is preferable. The drying method is not particularly limited, and examples thereof include methods used in the production of paper. For example, a cylinder dryer, a yankee dryer, hot air drying, a near infrared heater, an infrared heater and the like are preferable.

(Step of forming the first resin layer)
In the step of forming the first resin layer, a step of applying the first resin composition on at least one surface of the fiber layer obtained by the above-mentioned method and a step of curing the first resin composition. And a step of forming an intermittent portion. The step of forming the intermittent portion is preferably the step of forming the groove portion.

The first resin composition preferably contains a polymerization initiator. Since at least a part of the polymerization initiator remains in the resin layer, it is preferable that the first resin layer contains the polymerization initiator. Examples of the polymerization initiator added to the first resin composition include thermal polymerization initiators and photopolymerization initiators.

Examples of the thermal polymerization initiator include hydroperoxide, dialkyl peroxide, peroxyester, diacyl peroxide, peroxycarbonate, peroxyketal, ketone peroxide and the like. Specifically, benzoyl peroxide, diisopropylperoxycarbonate, t-butylperoxy (2-ethylhexanoate) dicumyl peroxide, dit-butyl peroxide, t-butylperoxybenzoate, t-butylhydro. Perkiside, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide and the like can be used. These polymerization initiators may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include a photoradical generator or a photocationic polymerization initiator. The photopolymerization initiator may be used alone or in combination of two or more.
Examples of the photoradical generator include benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,6-dimethylbenzoyldiphenylphosphine oxide, or 2,4,6-trimethylbenzoyldiphenyl. Examples include phosphine oxide. Among these, benzophenone or 2,4,6-trimethylbenzoyldiphenylphosphine oxide can be mentioned.
The photocationic polymerization initiator is a compound that initiates cationic polymerization by irradiation with radiation such as ultraviolet rays or electron beams. For example, aromatic sulfonium salt, aromatic iodonium salt, aromatic diazonium salt, aromatic ammonium salt and the like can be used. Can be mentioned.

The content of the polymerization initiator is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the first resin composition. The content of the polymerization initiator is preferably 10% by mass or less with respect to the total mass of the first resin composition.

The first resin composition may further contain an isocyanate compound. Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and the like. The isocyanate compound includes biuret-type, nurate-type, adduct-type and other polyisocyanates, and such polyisocyanates can also be used.

The content of the isocyanate compound is preferably 1% by mass or more, more preferably 5% by mass or more, based on the total mass of the first resin composition. The content of the isocyanate compound is preferably 50% by mass or less with respect to the total mass of the first resin composition.

Since some of the thermal polymerization initiator, photopolymerization initiator, and isocyanate compound as described above remain in an unreacted state, they are also contained in the first resin layer after curing.
The content of the polymerization initiator in the first resin layer is preferably 0.5% by mass or more and 20% by mass or less, and 1% by mass or more and 10% by mass or less, based on the total mass of the first resin layer. More preferably.
The content of the isocyanate compound in the first resin layer is preferably 3% by mass or more and 50% by mass or less, and 5% by mass or more and 30% by mass or less, based on the total mass of the first resin layer. Is more preferable.

The first resin composition may further contain a solvent. Solvents include esters such as ethyl acetate, butyl acetate and propyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl, dibutyl ketone and cyclohexanone, aromatics and hydrocarbons such as toluene, xylene and hexane, 1-propanol and the like. Examples include organic solvents such as alcohols.

In the step of applying the first resin composition, the first resin composition is applied on at least one surface of the fiber layer. As a coating machine that can be used in the step of coating the first resin composition, 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.

In the step of curing the first resin composition, only a part of the coated first resin composition may be cured, or the entire first resin composition may be cured. In the step of curing the first resin composition, when only a part of the coated first resin composition is cured, the step of curing the first resin composition and the step of forming the intermittent portion are simultaneously performed. It will be done. In the step of curing the first resin composition, when the entire first resin composition is cured, a step of forming an intermittent portion is provided after the step of curing the first resin composition. Become.

When only a part of the coated first resin composition is cured, for example, a sheet (photomask) in which a light-shielding pattern is formed in the shape of the intermittent portion to be formed is placed on the coating film of the first resin composition. By irradiating ultraviolet rays from the sheet (photomask) side, the coating film other than the portion where the light-shielding pattern is laminated can be cured. Then, the uncured portion of the first resin composition is removed by removing it by a washing treatment or the like using an organic solvent. Before the sheet (photomask) is placed on the coating film of the first resin composition, a part of the monomer components in the first resin composition may be cured to be in a semi-cured state.

When irradiating ultraviolet rays from the sheet (photomask) side, the amount of ultraviolet rays to be irradiated is not particularly limited, but for example, ultraviolet rays of 300 nm or more and 450 nm or less are 10 mJ / cm ² or more and 1000 mJ / cm ² or less. It is preferable to irradiate in a range. It is also preferable to irradiate the radiation in two or more divided doses. Specific examples of the lamp used for irradiation include a metal halide lamp, a high-pressure mercury lamp, an ultraviolet LED lamp, an electrodeless mercury lamp, and the like.

In the step of curing the first resin composition, when the entire coated first resin composition is cured, plasma is formed at a portion where an intermittent portion is desired to be formed after the first resin composition is completely cured. It is preferable to perform an etching process. Specifically, after the coating film of the first resin composition is completely cured by thermosetting and / or ultraviolet curing, plasma processing in which the portion where the intermittent portion is formed on the first resin layer becomes a void. Laminate the masks for. After that, by performing the plasma etching process, the plasma etching process is performed only on the void portion of the plasma processing mask. The plasma etching process may be repeated a plurality of times until the fiber layer is exposed.

As a method for forming the intermittent portion on the first resin layer, the following method can be adopted in addition to the above-mentioned method. For example, a method of completely curing the entire first resin composition and then cutting a portion where an intermittent portion is desired to be formed with a sharp metal or the like, a method of cutting by laser processing, a method of etching with short wavelength ultraviolet rays, or the like. Can be mentioned. Further, a method (pressing method) in which a mold having a convex portion is pressed before the first resin composition is cured and the first resin composition is cured in that state can also be adopted.

(Step of forming the second resin layer)
When the laminated sheet of the present invention has a second resin layer, the method for producing a laminated sheet further includes a step of forming the second resin layer. In this case, the step of forming the second resin layer may be provided before the step of forming the intermittent portion, or may be provided after the step of forming the intermittent portion. The step of forming the second resin layer is a step of applying the second resin composition on one surface of the fiber layer and on the surface opposite to the surface on which the first resin layer is provided. , A step of curing the second resin composition. Examples of the coating machine that can be used in the step of coating the second resin composition include the above-mentioned coating machines.

The second resin composition preferably contains a polymerization initiator. Moreover, the second resin composition may contain an isocyanate compound. Examples of the polymerization initiator and the isocyanate compound include the above-mentioned polymerization initiators. The content of the polymerization initiator is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the second resin composition. The content of the polymerization initiator is preferably 10% by mass or less with respect to the total mass of the second resin composition. The content of the isocyanate compound is preferably 1% by mass or more, more preferably 5% by mass or more, based on the total mass of the second resin composition. The content of the isocyanate compound is preferably 50% by mass or less with respect to the total mass of the second resin composition.

Since some of the thermal polymerization initiator, photopolymerization initiator, and isocyanate compound as described above remain in an unreacted state, they are also contained in the second resin layer after curing.
The content of the polymerization initiator in the second resin layer is preferably 0.5% by mass or more and 10% by mass or less, and 1% by mass or more and 5% by mass or less, based on the total mass of the second resin layer. More preferably.
The content of the isocyanate compound in the second resin layer is preferably 20% by mass or more and 90% by mass or less, and is 30% by mass or more and 70% by mass or less, based on the total mass of the second resin layer. Is more preferable.

The second resin composition preferably further contains a solvent. Examples of the solvent include the above-mentioned solvents.

As a curing method in the step of curing the second resin composition, for example, thermosetting or ultraviolet curing can be adopted. Thermosetting and UV curing can be performed at the same time.

When the second resin composition is cured by thermosetting, it is preferable to heat the coating film of the second resin composition in a temperature range of 70 ° C. or higher and 200 ° C. or lower. The heating time can be 10 minutes or more and 10 hours or less.

When the second resin composition is cured by ultraviolet curing, the amount of ultraviolet rays to be irradiated is not particularly limited, but for example, ultraviolet rays of 300 nm or more and 450 nm or less are emitted from 10 mJ / cm ² or more and 1000 mJ / cm ² It is preferable to irradiate in the following range. It is also preferable to irradiate the radiation in two or more divided doses. Specific examples of the lamp used for irradiation include a metal halide lamp, a high-pressure mercury lamp, an ultraviolet LED lamp, an electrodeless mercury lamp, and the like.

(Use)
The laminated sheet of the present invention can be used, for example, as a sheet for analysis and measurement. Specifically, a fluid or the like can be dropped onto the intermittent portion of the laminated sheet of the present invention to analyze the physical characteristics of the fluid, the type of the inclusion, the amount of the inclusion, and the like. In this case, a reagent or the like suitable for each measurement may be bonded to the inner wall of the intermittent portion. Above all, the laminated sheet of the present invention is preferably used as a biosensor. In this case, for example, an antibody or the like suitable for each measurement is bonded to the inner wall of the intermittent portion, and a biological liquid sample such as blood is dropped onto the intermittent portion to identify the substance contained in the biological liquid sample or to identify the substance. Quantification can be performed.

In addition to the above applications, the laminated sheet of the present invention may be used for substrates of electronic devices, electronic device members, optical members, window materials of various vehicles and buildings, interior materials, exterior materials, packaging materials, and the like. can.

The features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed in a limited manner by the specific examples shown below.

[Example 1]
<Preparation of phosphoric acid group-introduced cellulose fiber>
As softwood kraft pulp, pulp made by Oji Paper (solid content 93% by mass, ^{sheet shape with basis weight 208 g / m 2} , separated and measured according to JIS P 8121, Canadian standard drainage degree (CSF) is 700 ml) Was used as a raw material. 100 parts by mass (absolute dry mass) of the softwood kraft pulp is impregnated into a mixed aqueous solution of ammonium dihydrogen phosphate and urea, squeezed to 49 parts by mass of ammonium dihydrogen phosphate and 130 parts by mass of urea, and impregnated with a chemical solution. Obtained pulp. The obtained chemical-impregnated pulp was dried in a dryer at 105 ° C. to evaporate the water content and pre-dried. Then, the pulp was heated in a blower dryer set at 140 ° C. for 10 minutes to introduce a phosphoric acid group into the cellulose in the pulp to obtain phosphorylated pulp.

100 g of the obtained phosphorylated pulp was taken out by the pulp mass, 10 L of ion-exchanged water was poured, the mixture was stirred and uniformly dispersed, and then filtered and dehydrated to obtain a dehydrated sheet. The process was repeated twice. Next, the obtained dehydrated sheet was diluted with 10 L of ion-exchanged water, and a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a pulp slurry having a pH of 12 or more and 13 or less. Then, this pulp slurry was dehydrated to obtain a dehydrated sheet, and then 10 L of ion-exchanged water was added. After stirring and uniformly dispersing, the steps of filtering and dehydrating to obtain a dehydrated sheet were repeated twice.

A dehydrated sheet of phosphorylated cellulose was obtained twice by repeating the steps of introducing a phosphoric acid group and filtering and dehydrating the obtained dehydrated sheet in the same manner as above. The infrared absorption spectrum of the obtained dehydrated sheet was measured by FT-IR. As a result, ^{absorption based on the phosphate group was observed at 1230 cm -1} or more and 1290 cm ^-1 or less, and the addition of the phosphate group was confirmed.

<Fiber processing>
Ion-exchanged water was added to the obtained dehydrated sheet of twice-phosphorylated cellulose to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated three times with a wet atomizer (Ultimizer manufactured by Sugino Machine Limited) at a pressure of 245 MPa to obtain a fine fibrous cellulose dispersion.

<Measurement of substituent amount>
The amount of substituents introduced is the amount of phosphoric acid groups introduced into the fiber raw material, and the larger this value is, the more phosphoric acid groups are introduced. The amount of the substituent introduced was measured by diluting the target fine fibrous cellulose with ion-exchanged water so that the content was 0.2% by mass, treating with an ion-exchange resin, and titrating with an alkali. In the treatment with an ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) with a volume of 1/10 is added to a slurry containing 0.2% by mass of fibrous cellulose and shaken for 1 hour. Processing was performed. Then, the resin and the slurry were separated by pouring on a mesh having a mesh size of 90 μm. In the titration using alkali, the change in the value of electrical conductivity exhibited by the slurry was measured while adding a 0.1 N aqueous sodium hydroxide solution to the fibrous cellulose-containing slurry after ion exchange. That is, the amount of alkali (mmol) required in the first region of the curve shown in FIG. 4 (phosphate group) is divided by the solid content (g) in the slurry to be titrated, and the amount of substituent introduced (mmol / mmol /). g). As a result of calculation, it was 0.98 mmol / g.

<Measurement of fiber width>
The fiber width of the fine fibrous cellulose was measured by the following method.
The supernatant of the fine fibrous cellulose dispersion was diluted with water so that the concentration was 0.01% by mass or more and 0.1% by mass or less, and the solution was added dropwise to the hydrophilized carbon grid film. After drying, it was stained with uranyl acetate and observed with a transmission electron microscope (JEOL-2000EX, manufactured by JEOL Ltd.). As a result, it was confirmed that the cellulose was fine fibrous cellulose having a width of about 4 nm.

<Sheet>
Polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight: 4 million) was added to the fine fibrous cellulose dispersion so as to be 20 parts by mass with respect to 100 parts by mass of the fine fibrous cellulose. Then, the concentration was adjusted so that the solid content concentration was 0.6% by mass. The dispersion was weighed so that the finished basis weight of the sheet was 68 g / m ² , developed on a commercially available acrylic plate, and dried in a dryer at 70 ° C. for 24 hours. A dammed plate was placed on the acrylic plate so as to have a predetermined basis weight. By the above procedure, a sheet (A) to be a fiber layer later was obtained, and the thickness thereof was 45 μm.

<Lamination of the first resin layer>
100 parts by mass of an acrylic resin containing pentaerythritol tetraacrylate as a main component (Beamset 710 manufactured by Arakawa Chemical Industries, Ltd.), 100 parts by mass of methyl ethyl ketone, and 5 parts by mass of a radical polymerization initiator (BASF, Irgacure 184) are mixed. The first resin composition was obtained. Next, the first resin composition was applied to one surface of the sheet (A) with a bar coater, and then heated at 100 ° C. for 5 minutes to volatilize the methyl ethyl ketone. Next, a 7 cm square photomask in which 10 linear light-shielding patterns having a width of 2000 μm were evenly formed on the surface of the sheet (A) coated with the resin composition (A) (each linear light-shielding pattern is: It was parallel and extended to both ends of the photomask). The first resin composition was cured by irradiating with ultraviolet rays of ^{500 mJ / cm 2} using a UV conveyor device (ECS-4011GX manufactured by Eye Graphics Co., Ltd.) to form a first resin layer. By the above procedure, a laminated sheet (B) in which the first resin layer was laminated on the fiber layer was formed, and the thickness of the first resin layer was 10 μm.

<Formation of intermittent part (groove part)>
The laminated sheet (B) was immersed in a metal container filled with methyl ethyl ketone. Next, the metal container was placed on a shaking device (PersonalLt-10F manufactured by Titec Co., Ltd.), and the shaking washing treatment was performed for 5 minutes. By repeating this operation twice with the methyl ethyl ketone replaced, the first resin composition existing in the light-shielding pattern portion of the photomask was removed, and a laminated sheet in which a groove-shaped intermittent portion was formed in the first resin layer (a laminated sheet ( C) was obtained. It was confirmed that the fiber layer was exposed at the intermittent portion of the laminated sheet (C).

<Lamination of second resin layer>
100 parts by mass of acrylic resin graft-polymerized with acryloyl group (Acryt 8KX-012C manufactured by Taisei Fine Chemical Co., Ltd .: acrylic resin component 39.0% by mass, 1-propanol 30.5% by mass, butyl acetate 30.5% by mass), poly A second resin composition was obtained by mixing 38 parts by mass of an isocyanate compound (TPA-100 manufactured by Asahi Kasei Chemicals Co., Ltd.) and 2 parts by mass of a radical polymerization initiator (Irgacure 184 manufactured by BASF Co., Ltd.). Next, the second resin composition was applied to the surface of the fiber layer on which the first resin layer was not formed with a bar coater, and then heated at 100 ° C. for 1 hour to be cured to form the second resin layer. .. By the above procedure, a laminated sheet (D) in which the first resin layer, the fiber layer, and the second resin layer were laminated in this order was formed, and the thickness of the second resin layer was 10 μm. In addition, in the step of <lamination of the first resin layer>, a portion (7 cm square portion) in which the photomask was left to stand was cut out and used as an evaluation sheet for the laminated sheet (D).

[Example 2]
In Example 1, a laminated sheet and an evaluation sheet in which groove-shaped intermittent portions were formed in the first resin layer were obtained in the same manner as in Example 1 except that the second resin layer was not laminated.

[Example 3]
In Example 1, instead of the photomask used when forming the intermittent portion, a 7 cm square photomask in which 10 linear light-shielding patterns having a width of 50 μm were uniformly formed in the plane (each linear light-shielding pattern is , Parallel and extending to both ends of the photomask), the same as in Example 1, with the laminated sheet and the evaluation sheet having groove-shaped intermittent portions (grooves) formed in the first resin layer. Obtained.

[Example 4]
The entire surface of the first resin layer was cured to obtain a laminated sheet (B) without using the photomask used in <Lamination of the first resin layer> of Example 1. Next, a stainless steel plasma processing mask in which 10 linear voids (defects) having a width of 5 μm and a length of 7 cm were uniformly formed in the plane on the first resin layer of the laminated sheet (B). It was left still. Then, the laminated sheet (B) was allowed to stand in the chamber of a plasma etching apparatus (NE-550X manufactured by ULVAC, Inc.) and subjected to plasma etching treatment. Then, a portion (7 cm square portion) of the laminated sheet (B) on which the plasma processing mask was left to stand was cut out to obtain an evaluation sheet. Other operations were the same as in Example 1.

[Example 5]
In <Lamination of the first resin layer> of Example 3, the composition of the first resin composition was changed as follows. Specifically, 20 parts by mass of a polyvinyl alcohol resin (PVA105 manufactured by Kuraray Co., Ltd.) and 80 parts by mass of ion-exchanged water were mixed to obtain a first resin composition. The thickness of the laminated first resin layer was 10 μm. Except for the above, in the same manner as in Example 3, a laminated sheet and an evaluation sheet in which groove-shaped intermittent portions (groove portions) were formed in the first resin layer were obtained.

[Comparative Example 1]
In Example 1, the sheet (A) was not used, and the resin layer was formed on the light peeling separator in which the silicon peeling layer was formed on the PET film. The formation of the resin layer was repeated four times to form a resin sheet having a thickness of 45 μm (this resin sheet later became the first resin layer). Next, a second resin layer was formed on one surface of the resin sheet (first resin layer). After that, the light release separator is peeled off from the resin sheet (first resin layer), and an intermittent portion (groove portion) is formed from the other surface side of the resin sheet (first resin layer) in the same procedure as in Example 1. A laminated sheet and an evaluation sheet in which groove-shaped intermittent portions (groove portions) were formed in the first resin layer were obtained.

[Comparative Example 2]
When forming the resin sheet of Comparative Example 1, the composition of the first resin composition was changed as follows. Specifically, 20 parts by mass of a polyvinyl alcohol resin (PVA105 manufactured by Kuraray Co., Ltd.) and 80 parts by mass of ion-exchanged water were mixed to obtain a first resin composition. The thickness of the obtained resin sheet was 45 μm. Except for the above, in the same manner as in Comparative Example 1, a laminated sheet and an evaluation sheet in which groove-shaped intermittent portions (groove portions) were formed in the first resin layer were obtained.

[Comparative Example 3]
In the <sheeting> of Example 1, a fibrous cellulose suspension was used instead of the fine fibrous cellulose dispersion. The fibrous cellulose suspension was produced as follows. Ion-exchanged water was added to softwood bleached kraft pulp (water content 50% by mass, Canadian standard drainage (CSF) 700 ml measured according to JIS P8121) to make a 1.0% by mass pulp suspension. .. This pulp suspension was treated with a lab refiner machine (manufactured by Aikawa Iron Works Co., Ltd.) at 10,000 rpm for 5 hours to obtain a fibrous cellulose suspension. The average fiber width of the fibrous cellulose contained in this fibrous cellulose suspension was 3 μm. The finished basis weight of the sheet was 45 g / m ² , and the thickness of the obtained sheet was 45 μm. Except for the above, in the same manner as in Example 1, a laminated sheet and an evaluation sheet in which groove-shaped intermittent portions (groove portions) were formed in the first resin layer were obtained.

<Measurement>
The evaluation sheets obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were measured according to the following method.

[Width of intermittent part (groove part)]
The intermittent portion of the evaluation sheet was observed with an optical microscope, and the maximum width of the intermittent portion was measured. As for the maximum width of the intermittent portion, the maximum width of any 10 points in the intermittent portion was measured, and the average value thereof was taken as the maximum width of the intermittent portion.

[Aspect ratio of intermittent part (groove part)]
The maximum width of the intermittent portion was divided by the thickness of the first resin layer to obtain the aspect ratio (W / T) of the intermittent portion.

<Evaluation>
The evaluation sheets obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated according to the following methods.

[Function as a flow path of the intermittent part (groove part)]
A test solution was prepared by mixing 95 parts by mass of isopropyl alcohol and 5 parts by mass of a dye (CI Acid Red 52 manufactured by Tokyo Chemical Industry Co., Ltd.). Next, 50 μL of the test solution was dropped onto one of the ends of the intermittent portion (groove portion) of the evaluation sheet with a micropipette. Further, the evaluation sheet was tilted by 20 °, and after 1 minute, the evaluation sheet was observed and evaluated according to the following criteria.
⊚: The test solution is observed only in the groove, and the test solution reaches the other end.
◯: The test solution is observed only in and around the groove, and the test solution reaches the other end.
Δ: The test solution is observed on the back surface of the fiber layer, but the test solution reaches the other end.
X: The test solution is observed on the back surface of the fiber layer, and the test solution does not reach the other end.

[Tensile resistance]
The evaluation sheet was cut into a width of 15 mm so that the extending direction of the groove and the longitudinal direction of the evaluation sheet were orthogonal to each other to obtain a test piece. Using this test piece, it conforms to JIS P 8113 except that the distance between chucks is 50 mm, and uses a tensile tester (Tensile Tester CODE SE-064 manufactured by L & W) at a temperature of 23 ° C. and a relative humidity of 50%. Tensile strength (unit: N / m) was measured. The tensile strength was divided by the thickness of the test piece (thickness measured in the region where the intermittent portion (groove portion) does not exist) to obtain the tensile strength (unit: MPa). Based on the calculated tensile strength, evaluation was performed according to the following criteria.
⊚: The tensile strength is 80 MPa or more.
◯: The tensile strength is 65 MPa or more and less than 80 MPa.
Δ: The tensile strength is 50 MPa or more and less than 65 MPa.
X: The tensile strength is less than 50 MPa.

As is clear from Table 1, in the example provided with the fiber layer containing the fine fibrous cellulose, the intermittent portion functioned well as a flow path, and the tensile resistance of the laminated sheet was excellent.
Regarding the function of the intermittent portion as a flow path, it is better in Examples 1 to 4 in which the hydrophobic resin is used in the first resin layer than in Example 5 in which the hydrophilic resin is used for the first resin layer. It became an evaluation. Further, regarding the tensile resistance, the evaluation was more excellent in Examples 1 and 3 to 5 having the second resin layer than in Example 2 having no second resin layer.
On the other hand, in Comparative Examples 1 and 2 having no fiber layer, the tensile resistance was significantly inferior. Further, in Comparative Example 3 which did not contain fine fibrous cellulose and had a fibrous layer composed of fibrous cellulose, the function of the intermittent portion as a flow path was significantly inferior.

10 Laminated sheet 12 Fiber layer 14 First resin layer 16 Second resin layer 20 Intermittent part

Claims (7)

A fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a first resin layer on at least one surface of the fiber layer are provided.
The first resin layer may have a discontinuous portion in a part,
The intermittent portion is a groove portion and is
A laminated sheet including an exposed surface of the fiber layer as a part of the constituent surface of the groove portion. The laminated sheet according to claim 1 , wherein the maximum width of the groove is 1 μm or more and 10 mm or less. The laminated sheet according to claim 1 or 2 , wherein when the maximum width of the groove is W and the depth of the groove is T, the value represented by W / T is 0.1 or more and 1000 or less. The laminated sheet according to any one of claims 1 to 3 , wherein the groove is a flow path for flowing a fluid. The laminated sheet according to any one of claims 1 to 4 , wherein the first resin layer contains a hydrophobic resin. The aspect according to any one of claims 1 to 5 , wherein the second resin layer is further provided on one surface of the fiber layer and on the surface opposite to the surface on which the first resin layer is provided. Laminated sheet. The laminated sheet according to any one of claims 1 to 6 , wherein the tensile strength is 65 MPa or more.

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