JP6965912B2 - Laminated body and manufacturing method of laminated body - Google Patents

Description

The present invention relates to a laminate and a method for producing a laminate.

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. Further, a sheet composed of such fine fibrous cellulose and a composite containing a fine fibrous cellulose-containing sheet and a resin layer have been developed. It is known that in sheets and composites containing fine fibrous cellulose, the contact points between fibers are remarkably increased, so that the tensile strength and the like are greatly improved. It is also known that the transparency is greatly improved when the fiber width is shorter than the wavelength of visible light.

For example, Patent Documents 1 to 3 disclose a laminate in which a resin layer composed of a resin such as polyethylene terephthalate or nylon and a fine fibrous cellulose-containing sheet are laminated. In these documents, in order to improve the adhesion between the resin layer and the fine fibrous cellulose-containing sheet, it is proposed to perform surface treatment such as corona treatment or to use a hydrophilic base material as the resin layer. There is. Further, Patent Document 3 proposes to improve the adhesion between the resin layer and the fine fibrous cellulose-containing sheet by blending a silane coupling agent in the fine fibrous cellulose-containing sheet. Further, Patent Document 4 proposes that a polycarbonate sheet is heat-fused to a fine fibrous cellulose-containing sheet to form a laminate. Here, the fine fibrous cellulose-containing sheet and the polycarbonate sheet, which have been previously impregnated with a primer treatment liquid such as an acrylic primer, are heat-sealed to form a laminate.

Japanese Unexamined Patent Publication No. 2015-218421 International Publication WO2013 / 042653 International Publication WO2011 / 118360 Japanese Unexamined Patent Publication No. 2010-023275

However, in the conventional laminate, the adhesion between the fine fibrous cellulose-containing sheet (fiber layer) and the resin layer is not sufficient, and further improvement may be required in terms of use.
Therefore, in order to solve the problems of the prior art, the present inventors have an object of providing a laminate of a fine fibrous cellulose-containing sheet (fiber layer) and a resin layer having better adhesion. We proceeded with the examination.

As a result of diligent studies to solve the above problems, the present inventors have conducted a laminate having a fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a resin layer in contact with one surface of the fiber layer. It has been found that the adhesion between the fiber layer and the resin layer can be improved by setting the water contact angle of the surface of the resin layer on the fiber layer side within a predetermined range.
Specifically, the present invention has the following configuration.

[1] At least one fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and a resin layer in contact with one surface of the fiber layer are provided, and distilled water is dropped on the surface of the resin layer on the fiber layer side. A laminated body having a water contact angle of 60 ° or less after 30 seconds.
[2] The laminate according to [1], wherein the resin layer contains at least one selected from a polycarbonate resin and an acrylic resin.
[3] The laminate according to [1] or [2], wherein the surface of the resin layer on the fiber layer side has a hydrophilic group.
[4] The laminate according to any one of [1] to [3], wherein the surface of the resin layer on the fiber layer side contains an organosilicon compound.
[5] The laminate according to any one of [1] to [4], wherein the surface of the resin layer on the fiber layer side has a fine concavo-convex structure.
[6] The laminate according to any one of [1] to [5], wherein the density of the fiber layer is 1.0 g / cm ^{3 or more.}
[7] A step of hydrophilizing at least one surface of the resin layer so that the water contact angle 30 seconds after dropping the distilled water is 60 ° or less, and a step of hydrophilizing the resin layer on the surface of the fibers. A method for producing a laminate, which comprises a step of applying a fine fibrous cellulose dispersion liquid containing fibrous cellulose having a width of 1000 nm or less.
[8] The method for producing a laminate according to [7], further comprising a step of forming a fine concavo-convex structure before the hydrophilization treatment step.

According to the present invention, it is possible to obtain a laminate in which the adhesion between the fiber layer containing fine fibrous cellulose and the resin layer is enhanced. Since the laminated body of the present invention is a laminated body having excellent adhesion, it can be applied to various uses.

FIG. 1 is a cross-sectional view illustrating the configuration of the laminated body of the present invention. FIG. 2 is a cross-sectional view illustrating the configuration of the laminated body of the present invention. FIG. 3 is a graph showing the relationship between the amount of NaOH added to the fiber raw material and the electrical conductivity.

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 body)
The present invention relates to a laminate having at least one fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less (hereinafter, also referred to as fine fibrous cellulose) and a resin layer in contact with one surface of the fiber layer. .. In the laminate of the present invention, the water contact angle of the surface of the resin layer on the fiber layer side 30 seconds after dropping the distilled water is 60 ° or less.
Since the laminate of the present invention has the above structure, it has excellent adhesion between the fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and the resin layer.

FIG. 1 is a cross-sectional view illustrating the configuration of the laminated body of the present invention. As shown in FIG. 1, the laminate 10 of the present invention has a fiber layer 2 and a resin layer 6. The fiber layer 2 and the resin layer 6 are laminated so as to be in contact with each other on one of the surfaces.

The laminate of the present invention may have at least one fiber layer 2 and one resin layer 6, but may have two or more fiber layers 2 and two or more resin layers 6. It may be. For example, FIG. 2 shows a laminate 10 having two resin layers 6. As shown in FIG. 2, the two resin layers 6 may be provided on both sides of the fiber layer 2. Further, the fiber layer 2 sandwiched between the resin layers 6 may be a multi-layered fiber layer.

In the laminate of the present invention, the water contact angle of the surface of the resin layer on the fiber layer side 30 seconds after dropping the distilled water may be 60 ° or less, preferably 50 ° or less, and 45 ° or less. Is more preferable, and 40 ° or less is further preferable. The lower limit of the water contact angle is not particularly set, but it is generally preferably 5 ° or more. By setting the water contact angle of the surface of the resin layer on the fiber layer side within the above range, the adhesion between the fiber layer and the resin layer can be more effectively enhanced. Here, when measuring the water contact angle of the surface of the resin layer on the fiber layer side, the laminate is immersed in ion-exchanged water for 24 hours, and then the fiber layer is peeled off from the resin layer. The water contact angle is a value measured in accordance with JIS R 3257, and 4 μL of distilled water is dropped on the surface of the resin layer on the fiber layer side, and a dynamic water contact angle tester (1100 DAT manufactured by Fibro) is used. It is a value measured 30 seconds after dropping using.
The water contact angle of the surface of the resin layer on the fiber layer side 30 seconds after dropping the distilled water is about the same before and after laminating with the fiber layer. That is, after laminating the resin layer with the fiber layer, the resin layer was peeled off by the above procedure, and the water contact angle of the surface of the resin layer on the fiber layer side was measured. The results of measuring the water contact angle of the surface arranged on the side are about the same.

As a method of setting the water contact angle of the surface of the resin layer on the fiber layer side within a desired range, for example, a method of applying a surface treatment to the resin layer can be mentioned. Examples of the surface treatment method include corona treatment, plasma discharge treatment, UV irradiation treatment, electron beam irradiation treatment, flame treatment and the like. Above all, the surface treatment is preferably at least one selected from the corona treatment and the plasma discharge treatment. The plasma discharge treatment is preferably a vacuum plasma discharge treatment.

Further, as a method of setting the water contact angle of the surface of the resin layer on the fiber layer side within a desired range, there is also a method of incorporating a hydrophilic group on the surface of the resin layer on the fiber layer side. Such a method may be applied in combination with the surface treatment method described above. Examples of the hydrophilic group include a hydroxyl group, a hydroxyalkyl group, a pyrrolidonyl group, a carboxyl group, a phosphoric acid group, a sulfone group, a carbonyl group, an amino group, a mercapto group and the like. Among them, the hydrophilic group is preferably at least one selected from a hydroxyl group, a carbonyl group and a carboxyl group.

When the amount of hydrophilic groups on the surface of the resin layer on the fiber layer side is Cx (mmol / g) and the amount of hydrophilic groups in the cross section at a position 50% in the thickness direction of the resin layer is Cy (mmol / g), Cx / Cy is preferably 1 or more, more preferably 5 or more, and even more preferably 10 or more. Here, the hydrophilic group amount is a numerical value measured by an X-ray electron spectroscope or an infrared spectrophotometer. In the measurement of the cross section at the position of 50% in the thickness direction of the resin layer, the cross section of the laminated body is cut out by Ultra Microtome UC-7 (manufactured by JEOL Ltd.), and the cross section is measured by the apparatus.

The surface of the resin layer on the fiber layer side preferably has an organosilicon compound. The organosilicon compound preferably has a hydrophilic group, and it is also preferable that the water contact angle of the surface of the resin layer on the fiber layer side is within a desired range by containing such a compound.

Examples of the organosilicon compound include a compound having a siloxane structure and a compound that forms a siloxane structure by condensation. For example, a silane coupling agent or a condensate of a silane coupling agent can be mentioned. The silane coupling agent may have a functional group other than the alkoxysilyl group, or may have no other functional group. Examples of the functional group other than the alkoxysilyl group include a vinyl group, an epoxy group, a styryl group, a methacryloxy group, an acryloxy group, an amino group, a ureido group, a mercapto group, a sulfide group and an isocyanate group. The silane coupling agent used in the present invention is preferably a silane coupling agent containing a methacryloxy group.

Specific examples of the silane coupling agent having a methacryloxy group in the molecule include methacryloxypropylmethyldimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, and methacryloxypropyltriethoxysilane. Examples thereof include 1,3-bis (3-methacryloxypropyl) tetramethyldisiloxane. Among them, at least one selected from methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane and 1,3-bis (3-methacryloxypropyl) tetramethyldisiloxane is preferably used. The silane coupling agent preferably contains 3 or more alkoxysilyl groups.

In the silane coupling agent, silanol groups are generated after hydrolysis, and at least a part of the silanol groups is present even after the fiber layers are laminated. Since the silanol group is a hydrophilic group, it becomes easy to set the water contact angle of the surface of the resin layer on the fiber layer side within a desired range.

In the laminate of the present invention, it is also preferable that the surface of the resin layer on the fiber layer side has a fine concavo-convex structure. Since the surface of the resin layer on the fiber layer side has a fine concavo-convex structure, the adhesion between the fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and the resin layer can be more effectively enhanced. When the surface of the resin layer on the fiber layer side has a fine concavo-convex structure, the water contact angle of the surface constituting the fine concavo-convex structure can be easily set to 60 ° or less.

In the present specification, the fine concavo-convex structure means a structure in which the number of recesses existing on one straight line having a length of 1 mm drawn at an arbitrary position is 10 or more. When measuring the number of recesses, the laminate is immersed in ion-exchanged water for 24 hours, and then the fiber layer is peeled off from the resin layer. After that, the surface of the resin layer on the fiber layer side can be measured by scanning with a stylus type surface roughness meter (Surfcoder series manufactured by Kosaka Research Institute). Scanning probe microscope (AFM5000II manufactured by Hitachi High-Tech Science Corporation) when the uneven pitch is submicron and nano-order extremely small.
, And the number of irregularities can be measured from the observation image of AFM5100N).

When the surface of the resin layer on the fiber layer side has a fine concavo-convex structure, such a structure is formed by, for example, a treatment step such as a blasting treatment, an embossing treatment, an etching treatment, a corona treatment, or a plasma discharge treatment. Is preferable.

When the surface of the resin layer on the fiber layer side has a fine concavo-convex structure, the arithmetic mean surface roughness (Ra) of the surface of the resin layer on the fiber layer side is preferably 0.07 μm or more and 1.00 μm or less. It is more preferably 08 μm or more and 0.75 μm or less, and further preferably 0.10 μm or more and 0.50 μm or less. Here, when measuring the arithmetic mean surface roughness (Ra), the laminate is immersed in ion-exchanged water for 24 hours, and then the fiber layer is peeled off from the resin layer. The arithmetic mean surface roughness (Ra) is a value measured by scanning the surface of the resin layer on the fiber layer side with a stylus type surface roughness meter (Surf coder series manufactured by Kosaka Research Institute). In the measurement, the measurement length is set to 8.0 mm, the cutoff value is set to 0.8 mm, and the measurement speed is set to 0.1 mm / sec.

The total thickness of the laminate of the present invention is not particularly limited, but is preferably 50 μm or more, more preferably 100 μm or more, and further preferably 200 μm or more. Further, the total thickness of the laminated body is preferably 20 mm or less. It is preferable to appropriately adjust the thickness of the laminate according to the application.

The thickness of the fiber layer of the laminated body is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. In addition, the thickness of the fiber layer is
It is preferably 500 μm or less, more preferably 200 μm or less.
It is more preferably 100 μm or less. Here, the thickness of the fiber layer constituting the laminate is measured by cutting out a cross section of the laminate with an ultramicrotome UC-7 (manufactured by JEOL Ltd.) and observing the cross section with an electron microscope, a magnifying glass or visually. Value. When the laminate contains a plurality of fiber layers, it is preferable that the total thickness of the fiber layers is within the above range.

The thickness of the resin layer of the laminated body is preferably 10 μm or more, more preferably 20 μm or more, further preferably 50 μm or more, further preferably 100 μm or more, and further preferably 200 μm or more. Is particularly preferred. The thickness of the resin layer is preferably 15,000 μm or less, more preferably 5000 μm or less, and even more preferably 500 μm or less. Here, the thickness of the resin layer constituting the laminate is measured by cutting out a cross section of the laminate with an ultramicrotome UC-7 (manufactured by JEOL Ltd.) and observing the cross section with an electron microscope, a magnifying glass or visually. Value. When the laminate contains a plurality of resin layers, the total thickness of the resin layers is preferably within the above range.

In the laminate of the present invention, the thickness of the resin layer is preferably 30% or more, more preferably 100% or more of the thickness of the fiber layer. When the laminate has at least one of the fiber layer and the resin layer, the ratio of the total thickness of the resin layer to the total thickness of the fiber layer (total thickness of the resin layer / thickness of the fiber layer). The total) is preferably 0.5 or more. By setting the ratio of the total thickness of the resin layer to the total thickness of the fiber layer in the above range, the mechanical strength of the laminate can be increased.

The total light transmittance of the laminated body is preferably 60% or more, more preferably 65% or more, further preferably 70% or more, and particularly preferably 85% or more. By setting the total light transmittance of the laminate within the above range, it becomes easy to apply the laminate of the present invention to applications to which transparent glass has been conventionally applied. Here, the total light transmittance is a value measured using a haze meter (manufactured by Murakami Color Technology Research Institute, HM-150) in accordance with JIS K 7361.

The haze of the laminate is preferably 20% or less, more preferably 15% or less, further preferably 10% or less, and particularly preferably 5% or less. The lower the haze, the easier it is to apply the laminate of the invention to applications where transparent glass has traditionally been applied. Here, the haze is a value measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7136.

The tensile elastic modulus of the laminate at 23 ° C. and 50% relative humidity is preferably 2.5 GPa or more, more preferably 5.0 GPa or more, and even more preferably 10 GPa or more. The tensile elastic modulus of the laminate at 23 ° C. and 50% relative humidity is preferably 30 GPa or less, more preferably 25 GPa or less, and even more preferably 20 GPa or less. The tensile elastic modulus of the laminate is a value measured in accordance with JIS P 8113.

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

The density of the fiber layer ^{is preferably 1.0 g / cm 3} or more, more preferably 1.2 g / cm ³ or more, and even more preferably 1.4 g / cm ³ or more. The density of the fiber layer is preferably 1.7 g / cm ³ or less, more preferably 1.65 g / cm ³ or less, further preferably 1.6 g / cm ³ or less. When the laminate contains two or more fiber layers, the density of each fiber layer is preferably within the above range.

The density of the fiber layer is calculated from the basis weight and thickness of the fiber layer in accordance with JIS P 8118. The basis weight of the fiber layer can be calculated by cutting with Ultra Microtome UC-7 (manufactured by JEOL Ltd.) so that only the fiber layer of the laminate remains, and in accordance with JIS P 8124. When the fiber layer contains an optional component other than the fine fibrous cellulose, the density of the fiber layer is a density including an optional component other than the fine fibrous cellulose.

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

<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). Examples thereof include 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), 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. A fiber layer containing fine fibrous cellulose of long fibers having a large axial ratio tends to obtain high strength.

The average fiber width of the fine fibrous cellulose is 1000 nm or less when observed with an electron microscope. The average fiber width is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and further preferably 2 nm or more and 10 nm or less, but is not particularly limited. 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 prepare 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 (sometimes simply referred to as "fiber width") 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 a 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.

The ratio of the crystal portion contained in the fine fibrous cellulose is not particularly limited in the present invention, but it is preferable to use cellulose having a crystallinity of 60% or more determined by the X-ray diffraction method. The crystallinity is preferably 65% or more, more preferably 70% or more, and 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 a substituent, and the substituent is preferably an anionic group. Examples of the anion group include a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group), a carboxyl group or a substituent derived from a carboxyl group (sometimes simply referred to as a carboxyl group), and the like. And, it is preferable that it is at least one selected from a sulfone group or a substituent derived from a sulfone group (sometimes simply referred to as a sulfone group), and at least one selected from a phosphoric acid group and a carboxyl group. It is more preferable, and it is particularly preferable that it is a phosphate group.

The fine fibrous cellulose preferably has a phosphoric acid group or a substituent derived from the 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 phosphoric acid groups include substituents such as a group obtained by decomposing a phosphoric acid group, a salt of a phosphoric acid group, and a phosphoric acid ester group, and even if it is an ionic substituent, it is a nonionic substituent. It may be a group.

In the present invention, the phosphate 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 to n) 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 phosphate group introduction step, 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") is reacted with a fiber raw material containing cellulose. 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 phosphate 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").

As an example of the method of allowing the compound A to act on the fiber raw material in the coexistence of the compound B, a method of mixing the powder or the aqueous solution of the compound A and the compound B with the fiber raw material in a dry state or a wet state can be mentioned. 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 that exhibits acidity and an alkalinity in combination 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.

It is preferable to perform heat treatment in the phosphoric acid group introduction step. The heat treatment temperature is preferably selected so that the phosphoric acid 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 130 ° 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, if the fiber raw material is allowed to stand for a long time while the fiber raw material slurry to which the compound A is added contains water, 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 agitated 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 phosphoric acid groups to the hydroxyl groups to the outside of the device system. For example, a ventilation 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 amount of the phosphoric acid group introduced is preferably 0.1 mmol / g or more and 3.5 mmol / g or less, and more preferably 0.14 mmol / g or more and 2.5 mmol / g or less per 1 g (mass) of fine fibrous cellulose. , 0.2 mmol / g or more and 2.0 mmol / g or less, more preferably 0.2 mmol / g or more and 1.8 mmol / g or less, and 0.4 mmol / g or more and 1.8 mmol / g or less is particularly preferable. It is preferably 0.6 mmol / g or more and 1.8 mmol / g or less. By setting the amount of the phosphoric acid group introduced 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. Further, by setting the amount of the phosphoric acid group introduced within the above range, the viscosity of the slurry of fine fibrous cellulose can be adjusted within an appropriate range.

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. At first, 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. 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. 3 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.

<Alkaline treatment>
When producing fine fibrous cellulose, an alkali treatment may be performed between the phosphoric acid 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 phosphate group-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, and 1000% by mass or more and 10000% by mass or less with respect to the absolute dry mass of the phosphate group-introduced fiber. Is more preferable.

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

<Fiber processing>
The phosphoric acid group-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, use 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. 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.

The fine fibrous cellulose-containing material having a phosphoric acid group obtained by the above-mentioned method is a fine fibrous cellulose-containing slurry, and may be diluted with water so as to have a desired concentration.

<Arbitrary ingredient>
The fiber layer may contain an arbitrary component other than fine fibrous cellulose. Examples of the optional component include hydrophilic polymers and organic ions. The hydrophilic polymer is preferably a hydrophilic oxygen-containing organic compound (however, the above-mentioned cellulose fibers are excluded). The oxygen-containing organic compound is preferably non-fibrous, and such non-fibrous oxygen-containing organic compound does not include fine fibrous cellulose or thermoplastic resin fiber.

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. The hydrophilic oxygen-containing organic compound preferably has an SP value of, for example, 9.0 or more. Further, the hydrophilic oxygen-containing organic compound is preferably one in which 1 g or more of the oxygen-containing organic compound is dissolved in 100 ml of ion-exchanged water, for example.

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.); hydrophilics such as glycerin, sorbitol, ethylene glycol, etc. Sexual small molecules can be mentioned. Among these, polyethylene glycol, polyethylene oxide, glycerin, and sorbitol are preferable from the viewpoint of improving the strength, density, chemical resistance, etc. of the fiber layer, and at least one selected from polyethylene glycol and polyethylene oxide is more preferable. It is preferably polyethylene glycol, more preferably polyethylene glycol.

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 small molecule having a molecular weight of less than 1000.

The content of the oxygen-containing organic compound contained in the fiber layer is preferably 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the fine fibrous cellulose contained in the fiber layer, and is preferably 10 parts by mass or more and 30 parts by mass. It is more preferably 15 parts by mass or more and 25 parts by mass or less. By setting the content of the oxygen-containing organic compound within the above range, a laminate having high transparency and strength can be formed.

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.

(Resin layer)
The resin layer is a layer containing a resin such as a natural resin or a synthetic resin as a main component. Here, the main component refers to a component contained in an amount of 50% by mass or more with respect to the total mass of the resin layer. The content of the resin 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, based on the total mass of the resin layer. The above is particularly preferable. The resin content may be 100% by mass or 95% by mass or less.

Examples of the natural resin include rosin-based resins such as rosin, rosin ester, and hydrogenated rosin ester.

As the synthetic resin, for example, at least one selected from polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polyimide resin, polystyrene resin and acrylic resin is preferable. Among them, the synthetic resin is preferably at least one selected from the polycarbonate resin and the acrylic resin, and more preferably the polycarbonate resin. The acrylic resin is preferably at least one selected from polyacrylonitrile and poly (meth) acrylate.

Examples of the polycarbonate resin constituting the resin layer include aromatic polycarbonate-based resins and aliphatic polycarbonate-based resins. These specific polycarbonate-based resins are known, and examples thereof include the polycarbonate-based resins described in JP-A-2010-023275.

In the present invention, the water contact angle of the surface of the resin layer on the fiber layer side 30 seconds after dropping the distilled water may be 60 ° or less, preferably 50 ° or less, and more preferably 45 ° or less. It is preferably 40 ° or less, and more preferably 40 ° or less. By setting the water contact angle of the surface of the resin layer on the fiber layer side within the above range, the adhesion between the fiber layer and the resin layer can be more effectively enhanced.

As a method for setting the water contact angle of the surface of the resin layer on the fiber layer side within a desired range, the above-mentioned method can be mentioned, and the preferred enumeration is the same as above.

It is also preferable that the surface of the resin layer on the fiber layer side contains an organosilicon compound. The organosilicon compound can more effectively enhance the adhesion between the fiber layer and the resin layer. The above-mentioned compounds can be listed as preferable examples of the organosilicon compound.

It is also preferable that the surface of the resin layer on the fiber layer side has a fine concavo-convex structure. Since the surface of the resin layer on the fiber layer side has a fine concavo-convex structure, the adhesion between the fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less and the resin layer can be more effectively enhanced.
When the surface of the resin layer on the fiber layer side has a fine concavo-convex structure, the above-mentioned step can be mentioned as a step of forming such a structure.

The resin layer may contain an arbitrary component other than the synthetic resin. Examples of the optional component include known components used in the field of resin films such as fillers, pigments, dyes, and ultraviolet absorbers.

(Manufacturing method of laminated body)
In the present invention, at least one surface of the resin layer is hydrophilized so that the water contact angle 30 seconds after dropping the distilled water is 60 ° or less, and the surface of the resin layer is hydrophilized. It also relates to a step of applying a fine fibrous cellulose dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less, and a method for producing a laminate including the step.

In the step of hydrophilizing at least one surface of the resin layer so that the water contact angle is 60 ° or less, corona treatment, plasma discharge treatment, UV irradiation treatment, electron beam irradiation treatment, flame treatment, etc. may be performed. can. Above all, in the step of hydrophilization treatment, it is preferable to apply at least one selected from corona treatment and vacuum plasma discharge treatment.

When corona treatment is performed in the step of hydrophilization treatment, the treatment output is preferably 10 W or more and 500 W or less, and the treatment speed is 0.1 m / min or more and 250 m / min or less as the corona discharge treatment condition. preferable. The corona discharge treatment may be repeated once or more and 100 times or less. The corona discharge treatment can be performed using, for example, a corona surface modifier (TEC-4AX manufactured by Kasuga Electric Co., Ltd.).

When the plasma discharge treatment is performed in the step of hydrophilization treatment, the treatment output is preferably 50 W or more and 1000 W or less, and the treatment time is preferably 1 minute or more and 100 minutes or less as the plasma discharge treatment conditions. The plasma discharge treatment is preferably performed in the presence of oxygen gas, in which case the oxygen gas is charged under vacuum conditions and the gas flow rate is preferably adjusted to 1 mL / min or more and 50 mL / min or less. .. Further, the pressure in the chamber is preferably 10 Pa or more and 500 Pa or less. The plasma discharge treatment can be performed using, for example, a vacuum plasma processing apparatus (RIE.S-200A manufactured by Kagami Semiconductor Co., Ltd.).

The step of hydrophilizing treatment may include a step of imparting a hydrophilic group donor. Examples of the hydrophilic group donor include agents containing an organosilicon compound. As the agent containing an organosilicon compound, a silane coupling agent or an agent containing a condensate of the silane coupling agent is preferably used.
In the step of applying the hydrophilic group donor, the hydrophilic group donor may be coated or sprayed on at least one surface of the resin layer. Further, in the step of applying the hydrophilic group donor, the resin layer may be impregnated with the hydrophilic group donor. In the present invention, it is preferable to impregnate the resin layer with the organosilicon compound-containing solution. When the resin layer is impregnated with the organosilicon compound-containing solution, the concentration of the organosilicon compound-containing solution is preferably 0.1% by mass or more, more preferably 0.2% by mass or more. The concentration of the organosilicon compound-containing solution is preferably 20% by mass or less, and more preferably 10% by mass or less. By setting the concentration of the organosilicon compound-containing solution within the above range, the adhesion between the fiber layer and the resin layer can be more effectively enhanced.

In the step of hydrophilizing treatment, a surface treatment step such as corona treatment or vacuum plasma discharge treatment and a step of applying a hydrophilic group donor may be combined. For example, a step of applying a hydrophilic group donor may be performed after performing a corona treatment or a vacuum plasma discharge treatment.

After the step of hydrophilizing treatment, a step of applying a fine fibrous cellulose dispersion liquid (fine fibrous cellulose-containing slurry) is provided. In the present invention, the fiber layer is preferably formed by applying a fine fibrous cellulose dispersion liquid containing fibrous cellulose having a fiber width of 1000 nm or less on the surface of the resin layer that has been hydrophilized. .. That is, the fiber layer is preferably a coating layer. In this case, the solid content concentration of the fine fibrous cellulose dispersion is preferably 0.05% by mass or more, and more preferably 0.1% by mass or more. The solid content concentration of the fine fibrous cellulose dispersion is preferably 10% by mass or less.

The fine fibrous cellulose dispersion preferably contains an oxygen-containing organic compound. The content of the oxygen-containing organic compound is preferably 1 part by mass or more and 40 parts by mass or less, and 10 parts by mass or more and 30 parts by mass with respect to 100 parts by mass of the fine fibrous cellulose contained in the fine fibrous cellulose dispersion. It is more preferably 15 parts by mass or more and 25 parts by mass or less.

In the process of applying the fine fibrous cellulose dispersion, if the viscosity of the fine fibrous cellulose dispersion is low and unintentionally develops on the resin layer, a fiber layer having a predetermined thickness and basis weight can be obtained. A frame for blocking may be fixed on the resin layer for use. The quality of the dammed frame is not particularly limited, but it is preferable to select one in which the end portion of the fiber layer 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 applying the fine fibrous cellulose dispersion liquid, 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. When the coating temperature is at least the above lower limit value, the fine fibrous cellulose dispersion liquid 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 fine fibrous cellulose dispersion so that the finished basis weight of the fiber layer 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 fiber layer manufacturing step preferably includes a step of drying the fine fibrous cellulose dispersion coated on the resin layer. The drying method is not particularly limited, but may be a non-contact drying method or a method of drying while restraining the fiber layer, and these may be combined.

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. Although the heat drying method and the vacuum drying method may be combined, 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 150 ° 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. ..

In the manufacturing process of the laminate of the present invention, it is also preferable to further include a step of forming a fine concavo-convex structure before the hydrophilization treatment step. In the step of forming the fine concavo-convex structure, it is preferable to perform blasting treatment, embossing treatment, etching treatment, corona treatment, plasma discharge treatment and the like, and it is more preferable to perform blasting treatment. The blasting process is preferably a sandblasting process, and in this case, the process can be performed by scanning the surface of the fine powder together with the jet stream. The fine powder is preferably a corundum fine powder of 50 mesh or more and 120 mesh or less.

The step of forming the fine concavo-convex structure can be performed in combination with various steps performed in the hydrophilic treatment step. For example, the blasting treatment and the corona treatment may be combined, the blasting treatment and the plasma discharge treatment step may be combined, or the blasting treatment and the step of applying the hydrophilic group donor may be combined.

As a method for producing the laminate, in addition to the above-mentioned method, there is also a method in which a resin layer is placed on the fiber layer and heat-pressed. Another method is to install a fiber layer in a mold for injection molding, inject a heated and melted resin into the mold, and bond the resin layer to the fiber layer.

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

The substance constituting the inorganic layer is not particularly limited, and is, for example, aluminum, silicon, magnesium, zinc, tin, nickel, titanium; these oxides, carbides, nitrides, oxide carbides, oxide nitrides, or oxide carbide nitrides. Things; or mixtures thereof. From the viewpoint that high moisture resistance can be stably maintained, silicon oxide, silicon nitride, silicon oxide carbide, silicon nitride, silicon oxide, aluminum oxide, aluminum nitride, aluminum oxide carbide, aluminum nitride, or any of these. The mixture is preferred.

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

Further, as a method for forming the inorganic layer, an atomic layer deposition method (ALD) can also be adopted. The ALD method is a method of forming a thin film in atomic layer units by alternately supplying the raw material gas of each element constituting the film to be formed to the surface on which the layer is formed. Although it has the disadvantage of a slow film formation rate, it has the advantage of being able to cleanly cover even a surface having a complicated shape and forming a thin film with few defects, as compared with the plasma CVD method. Further, the ALD method has an advantage that the film thickness can be controlled on the nano-order and it is relatively easy to cover a wide surface. Furthermore, the ALD method can be expected to improve the reaction rate, lower the temperature process, and reduce the amount of unreacted gas by using plasma.

The thickness of the inorganic layer is not particularly limited, but for example, for the purpose of exhibiting moisture-proof performance, it is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more. From the viewpoint of transparency and flexibility, the thickness of the inorganic layer is preferably 1000 nm or less, more preferably 800 nm or less, and further preferably 600 nm or less.

(Use)
A preferred embodiment of the laminate of the present invention is a laminate that is transparent, has high mechanical strength, and has a small haze. From the viewpoint of utilizing excellent optical characteristics, it is suitable for applications of light-transmitting substrates such as various display devices and various solar cells. It is also suitable for applications such as substrates for electronic devices, materials for home appliances, window materials for various vehicles and buildings, interior materials, exterior materials, and packaging materials.

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 as limited by the specific examples shown below.

<Example 1>
[Phosphorylation]
As the softwood kraft pulp, pulp manufactured by Oji Paper Co., Ltd. (solid content 93%, basis weight 208 g / m ² sheet, separated and measured according to JIS P 8121, Canadian standard drainage degree (CSF) 700 ml) is used. bottom. 100 parts by mass of the coniferous kraft pulp (absolutely dry mass) is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, squeezed to 45 parts by mass of ammonium dihydrogen phosphate and 200 parts by mass of urea, and impregnated with a chemical solution. Obtained pulp. The obtained chemical-impregnated pulp was dried and heat-treated in a hot air dryer at 165 ° C. for 200 seconds to introduce a phosphoric acid group into the cellulose in the pulp. The amount of phosphoric acid group introduced at this time was 0.98 mmol / g.

The amount of phosphoric acid group introduced was measured by diluting 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 (manufactured by Organo Corporation, Amber Jet 1024: conditioned) with a volume of 1/10 is added to a slurry containing 0.2 mass% cellulose and shaken for 1 hour. went. Then, it was poured onto a mesh having a mesh size of 90 μm to separate the resin and the slurry. 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 sodium hydroxide aqueous 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. 3 was divided by the solid content (g) in the slurry to be titrated to obtain the amount of substituent introduced (mmol / g).

[Alkaline treatment and cleaning]
Next, 5000 ml of ion-exchanged water was added to the cellulose into which the phosphate group was introduced, and the mixture was stirred and washed, and then dehydrated. The pulp after dehydration was diluted with 5000 ml of ion-exchanged water, and a 1N aqueous sodium hydroxide solution was added little by little until the pH became 12 or more and 13 or less with stirring to obtain a pulp dispersion. Then, this pulp dispersion was dehydrated, and 5000 ml of ion-exchanged water was added for washing. This dehydration washing was repeated once more.

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

[Hydrophilic treatment of resin layer]
A polycarbonate (PC) film (Teijin Co., Ltd., Panlite PC-2151: thickness 300 μm) was cut out to a size of 210 mm × 297 mm and allowed to stand in a corona surface modifier (manufactured by Kasuga Electric Co., Ltd., TEC-4AX). Next, the corona discharge treatment was performed at a processing output of 60 W and a processing speed of 1 m / min. The above corona discharge treatment was repeated 20 times to obtain a surface-treated polycarbonate film (a) having a hydrophilic surface.

[Laminate]
The concentration of the fine fibrous cellulose dispersion (A) was adjusted so that the solid content concentration was 0.5% by mass. Then, 20 parts by mass of a 0.5% by mass aqueous solution of polyethylene oxide (PEO-18 manufactured by Sumitomo Seika Chemical Co., Ltd.) was added to 100 parts by mass of the fine fibrous cellulose dispersion liquid (A) to disperse the fine fibrous cellulose. Liquid (B) was obtained. Next, the fine fibrous cellulose dispersion (B) was weighed so that the finished basis weight of the cellulose fiber layer (layer composed of the solid content of the fine fibrous cellulose dispersion (B)) was 50 g / m ^2. It was applied on the surface-treated polycarbonate film (a). Further, it was dried for 18 hours in a blower dryer at 70 ° C. A metal frame for damming (a circular gold frame having an inner dimension of 100 mm in diameter) was placed on the surface-treated polycarbonate film (a) so as to have a predetermined basis weight. By the above procedure, a laminate in which a fiber layer (cellulose fiber-containing layer) and a resin layer are laminated was obtained.

<Example 2>
[Hydrophilic treatment of resin layer]
A polycarbonate film (manufactured by Teijin Limited, Panlite PC-2151: thickness 300 μm) was cut out to a size of 150 mm × 150 mm and allowed to stand in a sandblasting machine. The surface of 80 mesh corundum fine powder was then scanned with a jet stream. Next, the polycarbonate film after the sandblasting process was allowed to stand in a vacuum plasma processing apparatus (manufactured by Kai Semiconductor Co., Ltd., RIE.S-200A). Plasma discharge treatment was performed with a treatment output of 300 W, an input gas of oxygen, a gas flow rate of 10 mL / min, a chamber pressure of 100 Pa, and a treatment time of 5 minutes. By the above treatment, a surface-treated polycarbonate film (b) having a hydrophilic surface was obtained.

[Laminate]
A laminated body in which the fiber layer and the resin layer were laminated was obtained in the same manner as in the lamination of Example 1 except that the surface-treated polycarbonate film (b) was used instead of the surface-treated polycarbonate film (a) as the resin layer.

<Example 3>
[Hydrophilic treatment of resin layer]
Dilute methacryloxypropyltrimethoxysilane (SILQUEST A-174 SILANE, manufactured by Momentive Performance Materials Japan) as an organosilicon compound (silane coupling agent) with ethanol to a concentration of 0.5% by mass. Then, a diluted solution of a silane coupling agent was obtained. Next, a polycarbonate film (manufactured by Teijin Limited, Panlite PC-2151: thickness 300 μm) was cut out to a size of 210 mm × 297 mm and immersed in the silane coupling agent diluted solution. Next, the polycarbonate film was pulled up, the upper end was sandwiched between double clips, and the film was hung in a constant temperature dryer, and heat-treated at 100 ° C. for 15 minutes. Further, heat treatment was carried out at 120 ° C. for 3 hours. By the above treatment, a surface-treated polycarbonate film (c) having a hydrophilic surface was obtained.

[Laminate]
A laminate in which the fiber layer and the resin layer were laminated was obtained in the same manner as in the lamination of Example 1 except that the surface-treated polycarbonate film (c) was used instead of the surface-treated polycarbonate film (a) as the resin layer.

<Example 4>
[Hydrophilic treatment of resin layer]
In the hydrophilization treatment of the resin layer of Example 3, a surface-treated polycarbonate film (d) having a surface hydrophilized in the same manner as in Example 3 except that the concentration of methacryloxypropyltrimethoxysilane was 5.0% by mass. ) Was obtained.

[Laminate]
A laminated body in which the fiber layer and the resin layer were laminated was obtained in the same manner as in the lamination of Example 1 except that the surface-treated polycarbonate film (d) was used instead of the surface-treated polycarbonate film (a) as the resin layer.

<Example 5>
[Hydrophilic treatment of resin layer]
In the hydrophilization treatment of the resin layer of Example 4, except that methacrylate, propyltriethoxysilane (manufactured by Momentive Performance Materials Japan, SILQUEST Y-9936 SILANE) was used instead of methacryloxypropyltrimethoxysilane. A surface-treated polycarbonate film (e) having a hydrophilic surface was obtained in the same manner as in Example 4.

[Laminate]
A laminated body in which the fiber layer and the resin layer were laminated was obtained in the same manner as in the lamination of Example 1 except that the surface-treated polycarbonate film (e) was used instead of the surface-treated polycarbonate film (a) as the resin layer.

<Example 6>
[Hydrophilic treatment of resin layer]
In the hydrophilization treatment of the resin layer of Example 4, the surface was the same as that of Example 4 except that 1,3-bis (3-methacryloxypropyl) tetramethyldisiloxane was used instead of methacryloxypropyltrimethoxysilane. A surface-treated polycarbonate film (f) in which is hydrophilic was obtained.

[Laminate]
A laminated body in which the fiber layer and the resin layer were laminated was obtained in the same manner as in the lamination of Example 1 except that the surface-treated polycarbonate film (f) was used instead of the surface-treated polycarbonate film (a) as the resin layer.

<Comparative example 1>
In Example 1, the procedure was the same as in Example 1 except that the resin layer was not hydrolyzed, to obtain a laminate in which the fiber layer and the resin layer were laminated.

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

[Thickness of laminate]
The thickness of the laminate was measured with a stylus type thickness gauge (Millitron 1202D manufactured by Marl Co., Ltd.).

[Thickness of resin layer]
The thickness of the resin layer before laminating was measured with a stylus type thickness gauge (Millitron 1202D manufactured by Marl Co., Ltd.) and used as the thickness of the resin layer in the laminated body.

[Thickness of fiber layer (cellulose fiber-containing layer)]
The thickness of the resin layer was reduced from the thickness of the laminate to obtain the thickness of the fiber layer (cellulose fiber-containing layer).

[Density of fiber layer (cellulose fiber-containing layer)]
The basis weight of the fiber layer (50 g / m ² ) was divided by the thickness of the fiber layer to obtain the density of the fiber layer.

[Water contact angle of resin layer]
After immersing the laminate in ion-exchanged water for 24 hours, the fiber layer was peeled off from the resin layer. Next, the water contact angle of the surface (the surface subjected to the hydrophilization treatment) arranged on the fiber layer side of the resin layer was measured. The measurement was performed in accordance with JIS R 3257, and 4 μL of distilled water was dropped on the surface of the resin layer using a dynamic water contact angle tester (1100 DAT manufactured by Fibro), and the water contact angle was measured 30 seconds after the dropping. It was set as a value.

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

[Adhesion between fiber layer and resin layer]
In accordance with JIS K 5400, ^{put 100 1 mm 2} crosscuts in the fiber layer of the laminate, attach cellophane tape (manufactured by Nichiban Co., Ltd.) on it, press it with a load of ^{1.5 kg / cm 2, and then press it.} It was separated in the 90 ° direction. The adhesion between the fiber layer and the resin layer was evaluated based on the number of separated cells.

[Total light transmittance of laminated body]
The total light transmittance of the laminate was evaluated using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7361.

[Laminated haze]
The haze of the laminate was evaluated using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7136.

As is clear from Table 1, in the examples in which the resin layer was hydrophilized, a laminate having good adhesion between the fiber layer and the resin layer was obtained while maintaining transparency. On the other hand, in the comparative example in which the hydrophilic treatment was not performed, although the transparency was maintained, the adhesion between the fiber layer and the resin layer was poor, resulting in concern about practical problems.

<Example 7 (Manufacturing example 1 of multilayer laminate)>
By the following procedure, a multilayer laminate in which resin layers are laminated on both sides of the fiber layer can be obtained.
Two laminates obtained in any of Examples 1 to 6 are prepared, and water is applied to each fiber layer with a bar coater. Next, the fiber layer surfaces of the two laminates are bonded together, and a rubber roller is pressed from the resin layer side of one laminate to pressurize. Further, the laminated laminate is dried at 100 ° C. for 1 hour in a constant temperature dryer to obtain a multilayer laminate in which resin layers are laminated on both sides of the fiber layer.

<Example 8 (Manufacturing example 2 of multilayer laminate)>
Two laminates obtained in any of Examples 1 to 6 are prepared, and a UV curable acrylic adhesive (manufactured by Aica Kogyo Co., Ltd., Z-587) is applied to each fiber layer with a bar coater. .. Next, the fiber layer surfaces of the two laminates are bonded together via a UV curable acrylic adhesive, and a rubber roller is pressed from the resin layer side of one laminate to pressurize. Further, from the resin layer side of the laminated body, a UV conveyor device (ECS-4011GX manufactured by Eye Graphics Co., Ltd.) is used to ^{irradiate ultraviolet rays of 500 mJ / cm 2} three times to apply a UV curable acrylic adhesive. By curing, a multilayer laminate in which resin layers are laminated on both sides of the fiber layer can be obtained.

<Example 9 (Manufacturing example 3 of multilayer laminate)>
Using the laminate obtained in any of Examples 1 to 6, a multilayer laminate in which resin layers are laminated on both sides can be obtained by the following procedure.
First, 100 parts by mass of an acrylic resin graft-polymerized with an acryloyl group (Acryt 8KX-012C manufactured by Taisei Fine Chemicals Co., Ltd.) and 38 parts by mass of a polyisocyanate compound (TPA-100 manufactured by Asahi Kasei Chemicals Co., Ltd.) are mixed to prepare a resin composition. obtain. Next, the resin composition is applied to the cellulose fiber-containing layer of the laminate with a bar coater. Further, by heating and curing at 100 ° C. for 1 hour, a multilayer laminate in which resin layers are laminated on both sides of the cellulose fiber-containing layer can be obtained.

<Example 10 (Production example 1 of inorganic film laminate)>
The laminate obtained in any of Examples 1 to 6 or the multilayer laminate obtained in any of Examples 7 to 9 is oxidized by an atomic layer deposition apparatus (SUNALE R-100B, manufactured by Picosun). Aluminum film is formed. Trimethylaluminium (TMA) is used as an aluminum raw material, and H ₂ O is used for oxidation of TMA. The chamber temperature is set to 150 ° C., the TMA pulse time is 0.1 seconds, the purge time is 4 seconds, the H ₂ O pulse time is 0.1 seconds, and the purge time is 4 seconds. By repeating this cycle for 405 cycles, an inorganic film laminate in which aluminum oxide films having a film thickness of 30 nm are laminated on both sides of the laminate can be obtained.

<Example 11 (Production example 2 of inorganic film laminate)>
Plasma CVD apparatus (ICP-CVD roll-to-roll apparatus manufactured by SELVAC) with respect to the laminate obtained in any of Examples 1 to 6 or the multilayer laminate obtained in any of Examples 7 to 9. A silicon oxynitride film is formed with. Specifically, the laminate is attached to the upper surface of the carrier film (PET film) with double-sided tape and installed in the vacuum chamber. The temperature inside the vacuum chamber is set to 50 ° C., and the inflow gas is silane, ammonia, oxygen, and nitrogen. A plasma discharge is generated to form a film for 45 minutes to obtain an inorganic film laminate in which a silicon oxynitride film having a thickness of 500 nm is laminated on one side of the laminate. Further, by forming a film on the opposite surface in the same procedure, it is possible to obtain an inorganic film laminate in which a silicon oxynitride film having a film thickness of 500 nm is laminated on both sides of the laminate.

2 Fiber layer 6 Resin layer 10 Laminated body

Claims (8)

A fiber layer containing fibrous cellulose having a fiber width of 1000 nm or less,
It has at least one resin layer in contact with one surface of the fiber layer.
The density of the fiber layer is 1.4 g / cm ³ or more.
A laminate having a water contact angle of 60 ° or less 30 seconds after dropping distilled water on the surface of the resin layer on the fiber layer side. The laminate according to claim 1, wherein the resin layer contains at least one selected from a polycarbonate resin and an acrylic resin. The laminate according to claim 1 or 2, wherein the surface of the resin layer on the fiber layer side has a hydrophilic group. The laminate according to any one of claims 1 to 3, wherein the surface of the resin layer on the fiber layer side contains an organosilicon compound. The laminate according to any one of claims 1 to 4, wherein the surface of the resin layer on the fiber layer side has a fine concavo-convex structure. The laminate according to any one of claims 1 to 5, wherein the average fiber width of the fibrous cellulose is 1000 nm or less. A step of hydrophilizing at least one surface of the resin layer so that the water contact angle 30 seconds after dropping the distilled water is 60 ° or less.
A fine fibrous cellulose dispersion containing fibrous cellulose having a fiber width of 1000 nm or less is applied onto the surface of the resin layer that has been hydrophilized to form a fibrous layer having a density of 1.4 g / cm ^{3 or more.} And a method of manufacturing a laminate including. The method for producing a laminate according to claim 7, further comprising a step of forming a fine concavo-convex structure before the hydrophilic treatment step.

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