JP2021091217A - Method for producing laminate - Google Patents

Abstract

To provide a laminate having a high modulus, low linear thermal expansion coefficient, and an excellent durability.SOLUTION: There is provided a method for producing a laminate that comprises a step of injecting a molten resin into a mold in which a sheet containing fibrous cellulose having a fiber width of 1000 nm or less is arranged; and a step of solidifying the molten resin, in which, in the laminate, the sheet containing fibrous cellulose is in a state of being covered by a resin component.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a laminate. Specifically, the present invention relates to a method for producing a laminate containing a fine fibrous cellulose-containing layer.

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 sheet containing a fine fibrous cellulose-containing sheet and a resin have been developed. In sheets and composite sheets containing fine fibrous cellulose, it is known that the strength and the like of the obtained sheets and composite sheets are greatly improved because the contact points between the fibers are increased.

For example, Patent Documents 1 to 4 disclose a composite sheet in which a layer containing fine fibrous cellulose and a resin layer are laminated. Patent Document 1 includes a transparent film layer made of regenerated cellulose and two transparent amorphous resin layers made of at least one resin selected from the group consisting of a polyacrylate-based resin and a polycarbonate-based resin. / Resin laminated composites are disclosed. Further, Patent Document 2 describes a step of applying a liquid composition containing cellulose nanofibers and a solvent to a base material, a step of removing the solvent from the liquid composition, a base material after removing the solvent, and a resin. A method for producing a fiber-resin composite including a step of compositing is disclosed.

Patent Document 3 describes a housing formed of a prepreg plate including a cellulose nanofiber layer in which cellulose nanofibers are adhered to the surface of a woven fabric made of multifiber yarn, and a resin layer adjacent to the nanofiber layer. Is disclosed. Further, Patent Document 4 discloses a laminate including a polycarbonate resin layer and a cellulose fiber layer, in which the thickness of the polycarbonate resin layer is 1.4 times or more the thickness of the cellulose fiber layer. A laminate is disclosed. In Patent Document 4, a laminated body is formed by laminating a polycarbonate resin layer and a cellulose fiber layer, and a part of the cellulose fiber layer is exposed.

Japanese Unexamined Patent Publication No. 2018-016066 JP-A-2017-222786 JP-A-2017-170829 Japanese Unexamined Patent Publication No. 2010-023275

In a composite sheet containing a fine fibrous cellulose-containing sheet and a resin layer, it is desirable to obtain a laminate showing a high elastic modulus and a low linear thermal expansion coefficient by laminating the fine fibrous cellulose-containing sheet and the resin layer. .. In addition, such laminates may be required to be durable.
Therefore, the present inventors have proceeded with studies for the purpose of providing a laminate having a high elastic modulus, a low coefficient of linear thermal expansion, and excellent durability.

As a result of diligent studies to solve the above problems, the present inventors have arranged a fine fibrous cellulose-containing sheet in a step of producing a laminate having a fine fibrous cellulose-containing layer and a resin layer. By injecting the molten resin into the provided mold, solidifying the molten resin, and encapsulating the fine fibrous cellulose-containing sheet with the resin component, the laminate has strength, dimensional stability, and durability. I found that I could get a body.

[1] A step of injecting a molten resin into a mold in which a sheet containing fibrous cellulose having a fiber width of 1000 nm or less is arranged.
A method for manufacturing a laminate including a step of solidifying a molten resin.
A method for producing a laminated body, wherein the sheet containing fibrous cellulose is wrapped with a resin component in the laminated body.
[2] The method for producing a laminate according to [1], wherein in the laminate, fibrous cellulose is unevenly distributed in an unexposed region in a region near the surface layer in the thickness direction of the laminate.
[3] In the step of injecting the molten resin, the sheets containing fibrous cellulose are arranged so as to face each other along both sides of the inner wall of the mold.
The method for producing a laminate according to [1] or [2], wherein at least a part of the molten resin is filled between sheets containing opposing fibrous celluloses.
[4] The method for producing a laminate according to any one of [1] to [3], wherein in the step of injecting the molten resin, the sheet containing fibrous cellulose is fixed to the inner wall of the mold via the resin sheet. ..
[5] The method for producing a laminate according to any one of [1] to [4], wherein the area of the maximum surface of the laminate is larger than the area of the maximum surface of the sheet containing fibrous cellulose.
[6] The method for producing a laminate according to any one of [1] to [5], wherein in the laminate, the edge of the sheet containing fibrous cellulose is covered with a resin component derived from a molten resin. ..
[7] The method for producing a laminate according to any one of [1] to [6], further comprising a step of coating an exposed portion of a sheet containing fibrous cellulose after a step of solidifying the molten resin.
[8] The method for producing a laminate according to any one of [1] to [7], wherein the molten resin contains an alloy resin containing a polycarbonate resin and an acrylic resin.

According to the present invention, it is possible to provide a laminate having a high elastic modulus, a low coefficient of linear thermal expansion, and excellent durability.

1 (a) and 1 (b) are schematic views explaining a method of manufacturing a laminated body. 2 (a) and 2 (b) are schematic views explaining the structure of the laminated body. 3A and 3B are cross-sectional views illustrating the configuration of the laminated body. 4 (a) and 4 (b) are cross-sectional views illustrating the configuration of the laminated body. 5 (a) and 5 (b) are cross-sectional views illustrating the configuration of the laminated body. 6 (a) and 6 (b) are cross-sectional views illustrating the configuration of the laminated body. 7 (a) and 7 (b) are cross-sectional views illustrating the structure of the laminated body. 8 (a) and 8 (b) are cross-sectional views illustrating the structure of the laminated body. 9 (a) and 9 (b) are cross-sectional views illustrating the configuration of the laminated body. FIG. 10 is a graph showing the relationship between the amount of NaOH added dropwise and the pH of the fibrous cellulose-containing slurry having a phosphorus oxo acid group. FIG. 11 is a graph showing the relationship between the amount of NaOH added dropwise to the fibrous cellulose-containing slurry having a carboxy group and the pH. 12 (a) and 12 (b) are cross-sectional views illustrating the structure of the laminated body. 13 (a) and 13 (b) are cross-sectional views illustrating the configuration of the laminated body obtained in the comparative example. 14 (a) and 14 (b) are cross-sectional views illustrating the configuration of the laminated body obtained in the comparative example. 15 (a) and 15 (b) are cross-sectional views illustrating the configuration of the laminated body obtained in the comparative example. 16 (a) and 16 (b) are cross-sectional views illustrating the configuration of the laminated body obtained in the comparative example. 17 (a) and 17 (b) are cross-sectional views illustrating the configuration of the laminated body obtained in the comparative example. 18 (a) and 18 (b) are cross-sectional views illustrating the configuration of the laminated body obtained in the comparative example.

Hereinafter, preferred embodiments of 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.

(Manufacturing method of laminated body)
One embodiment of the present invention is a method for producing a laminate. Here, the method for producing the laminate of the present embodiment includes a step of injecting the molten resin into a mold in which a sheet containing fibrous cellulose having a fiber width of 1000 nm or less is arranged, and a step of solidifying the molten resin. And, including. Then, in the laminate produced through the method for producing the laminate of the present invention, the sheet containing the fibrous cellulose is in a state of being encapsulated by the resin component.
In the present specification, fibrous cellulose having a fiber width of 1000 nm or less may be referred to as fine fibrous cellulose or CNF.

FIG. 1 is a schematic view illustrating a method for manufacturing a laminated body of the present embodiment. As shown in FIG. 1A, in the method for producing a laminate, first, a sheet containing fibrous cellulose having a fiber width of 1000 nm or less (fine fibrous cellulose-containing sheet 10) is arranged in a mold 50. To do. At this time, a laminated material may be laminated on the fine fibrous cellulose-containing sheet 10. The laminated material is preferably a resin sheet, and FIG. 1A exemplifies the resin sheet 20 as the laminated material.

As shown in FIG. 1, the mold 50 forms a gap. The gap portion may be formed of a series of mold constituent members, but may be formed by combining a set of mold constituent members. In FIG. 1, a set of molds 50 is formed by combining a mold constituent member having a concave portion and a mold constituent member having a convex portion. At this time, one internal gap is formed by combining and joining the mold constituent member having a concave portion and the mold constituent member having a convex portion. The shape of the mold component is not particularly limited as long as a gap is formed inside the mold. For example, a mold component having a recess and a mold component having a recess may be used. The mold may be formed by combining them.

When arranging the fine fibrous cellulose-containing sheet 10 in the mold 50, it is preferable to fix the fine fibrous cellulose-containing sheet 10 in the mold 50 by using a fixing means. In FIG. 1, the fixing member 52 is used to fix the fine fibrous cellulose-containing sheet 10 and the resin sheet 20 in the gap portion of the mold 50. Examples of the fixing member 52 include a heat-resistant tape, a clamp mechanism, a hook or pin for hanging, an electrostatic suction device, a vacuum suction device, and the like. When the mold 50 is composed of a set of mold constituent members, it is preferable to assemble the mold 50 after fixing the fine fibrous cellulose-containing sheet 10 by using a fixing means.

When the fine fibrous cellulose-containing sheet 10 is arranged in the mold 50, its fixing position can be appropriately adjusted. For example, the fine fibrous cellulose-containing sheet 10 may be fixed on the mold plane of the mold 50, or the fine fibrous cellulose-containing sheet 10 may be fixed away from the mold plane. In this way, by appropriately adjusting the fixing position of the fine fibrous cellulose-containing sheet 10 in the void portion of the mold 50, the arrangement position of the fine fibrous cellulose-containing sheet in the obtained laminate 100 can be controlled. In addition, in this specification, a mold plane is a plane which constitutes the maximum plane of the void part formed by assembling a mold. For example, when the mold is a combination of a mold constituent member having a concave portion and a mold constituent member having a convex portion, the mold plane is a concave bottom surface and is convex if the mold constituent member has a concave portion. If it is a mold component having a portion, it is the upper surface of the convex portion.

After fixing the fine fibrous cellulose-containing sheet 10 in the voids formed by the mold 50, a step of injecting the molten resin into the voids of the mold 50 is provided. At this time, it is preferable that the molten resin is injected from the injection port 51 of the mold 50, and the molten resin is injected at a predetermined pressure. The position where the injection port 51 is provided in the mold 50 is not particularly limited. For example, as shown in FIG. 1, the injection port 51 may be provided in the vicinity of the fixing member provided on the upper side. Further, the injection port 51 may be provided at a plurality of locations in the mold 50. Further, in the injection process of the molten resin, the temperature of the molten resin (the resin melting temperature at the time of molding), the mold clamping force at the time of molding, the holding time after the injection of the molten resin (the holding time at the time of molding), and the molten resin are used. It is preferable to appropriately adjust the mold temperature at the time of injection (mold temperature at the time of molding) and the like.

The pressure for injecting the molten resin is, for example, preferably 10 MPa to 500 MPa, more preferably 50 MPa to 400 MPa, and even more preferably 100 MPa to 300 MPa.
The resin melting temperature at the time of molding is preferably, for example, 100 to 400 ° C, more preferably 150 to 400 ° C, and even more preferably 200 to 400 ° C.
As the mold clamping force at the time of molding, for example, 200 kN to 100,000 kN is preferable, 500 kN to 50,000 kN is more preferable, and 1000 kN to 10000 kN is further preferable.
The holding time during molding is, for example, preferably 0.1 to 600 seconds, more preferably 1 to 300 seconds, and even more preferably 10 to 60 seconds.
The mold temperature at the time of molding is, for example, preferably 100 to 400 ° C, more preferably 100 to 300 ° C, and even more preferably 150 to 250 ° C.

Examples of the molten resin include resins obtained by melting polycarbonate resin, polyolefin resin, polyimide resin, polystyrene resin, acrylic resin and the like. The acrylic resin is preferably at least one selected from polyacrylonitrile and poly (meth) acrylate. Among them, the molten resin is preferably a molten resin containing at least one selected from a polycarbonate resin and an acrylic resin as a main component, and particularly preferably a molten resin containing a polycarbonate resin as a main component. The molten resin may be a resin obtained by melting an alloy resin containing a polycarbonate resin and an acrylic resin. When an alloy resin is used, the flexural modulus of the laminate tends to be higher and the linear thermal expansion coefficient tends to be smaller.

After the step of injecting the molten resin, a step of solidifying the molten resin is provided. In the step of solidifying the molten resin, for example, the resin may be solidified by lowering the mold temperature. In this case, the mold temperature in the step of solidifying the molten resin is preferably adjusted appropriately depending on the injected molten resin type, but is preferably less than 150 ° C., more preferably 130 ° C. or lower, and 110. It is more preferable to keep the temperature below ° C. As a result, the laminated body 100 is formed in the mold 50.

The step of solidifying the molten resin may be an active energy ray irradiation step when the molten resin used is an active energy ray-curable resin. In this case, examples of the active energy ray include ultraviolet rays, electron beams, visible rays, X-rays, and ion rays. Further, the step of solidifying the molten resin may be a heating step when the molten resin used is a thermosetting resin.

After the molten resin is solidified, the mold 50 is removed from the laminated body 100 to obtain the laminated body 100. At this time, the fixing member 52 may remain in the laminated body 100, or the fixing member 52 may be removed from the laminated body 100 together with the mold 50.

As described above, the method for producing the laminated body of the present embodiment is the method for producing the laminated body by the injection molding method as described above. The method for producing the laminated body of the present embodiment may be an injection compression molding method. The injection compression molding method is a molding method also called a coining molding method, a stamping molding method, a compression-filling molding method, or a hybrid molding method. In the injection compression molding method, a compression step is provided while injecting the molten resin and / or after injecting the molten resin. By providing the compression step, it is possible to obtain a laminate that is thinner and has less internal residual stress.

In the present embodiment, in the laminate obtained by the above-mentioned production method, the fine fibrous cellulose-containing sheet is in a state of being encapsulated by the resin component. That is, the method for producing a laminate of the present embodiment is a method for producing a laminate in which a fine fibrous cellulose-containing sheet is encapsulated with a resin component. The state in which the fine fibrous cellulose-containing sheet is covered with the resin component means that none of the fine fibrous cellulose-containing sheets is exposed on the surface, and the periphery thereof is covered with at least one kind of resin. The state of being. The resin component is a resin mainly used during injection molding, and the resin component may be composed of a resin used during injection molding, but a part of the resin component is derived from another resin member. It may be a component to be used. For example, the other resin member may be a resin sheet laminated in advance on a fine fibrous cellulose-containing sheet, or may be a cover resin that covers an exposed portion of the fine fibrous cellulose-containing sheet after forming the laminate. Good. That is, as the resin component, in addition to the resin injected into the mold at the time of injection molding, the resin component derived from the pre-laminated resin sheet and the exposed end portion of the fine fibrous cellulose-containing sheet are heated in the subsequent process. Contains resin components used for sealing.

The laminate produced by the method for producing a laminate of the present embodiment is excellent in strength and dimensional stability because it has a structure containing a fine fibrous cellulose-containing sheet. Specifically, the laminate obtained by the production method of the present embodiment has a high elastic coefficient and a low linear thermal expansion coefficient.

The bending elasticity of the laminate obtained by the production method of the present embodiment is preferably larger than 2.2 GPa, more preferably 2.3 GPa or more, further preferably 2.5 GPa or more. It is more preferably 0 GPa or more, further preferably 3.5 GPa or more, and particularly preferably 4.0 GPa or more. The flexural modulus of the laminated body is a value measured under the conditions of a distance between fulcrums of 64 mm and a deflection speed of 2 mm / min in accordance with JIS K 7171: 2016. At this time, the test piece is a test piece having a length of 80 mm and a width of 10 mm, and the test temperature is 23 ° C. Then, the flexural modulus is calculated from the slope of the stress / strain curve whose strain is between 0.0005 and 0.0025. A universal material tester can be used as a device for measuring the flexural modulus, and for example, Tencilon RTC-1250A manufactured by A & D Co., Ltd. can be used.

The flexural modulus of the laminate obtained by the production method of the present embodiment at high temperature is preferably greater than 2.0 GPa, more preferably 2.1 GPa or more, and further preferably 2.3 GPa or more. It is more preferably 2.5 GPa or more, further preferably 3.0 GPa or more, and particularly preferably 4.0 GPa or more. The flexural modulus of the laminate at high temperature is a value measured under the conditions of a distance between fulcrums of 64 mm and a deflection speed of 2 mm / min, in accordance with JIS K 7171: 2016, except that the test temperature is 80 ° C. .. At this time, the test piece is a test piece having a length of 80 mm and a width of 10 mm, and the test temperature is 80 ° C. Then, the flexural modulus is calculated from the slope of the stress / strain curve whose strain is between 0.0005 and 0.0025. A universal material tester can be used as a device for measuring the flexural modulus, and for example, Tencilon RTC-1250A manufactured by A & D Co., Ltd. can be used.

The linear thermal expansion coefficient of the laminate obtained by the production method of the present embodiment is preferably 70 ppm / K or less, more preferably 65 ppm / K or less, and further preferably 60 ppm / K or less. It is more preferably 55 ppm / K or less, and particularly preferably 50 ppm / K or less. The linear thermal expansion coefficient of the laminated body is obtained by measuring the amount of change in length under the conditions of a temperature range of 23 to 90 ° C. and a temperature rise rate of 5 ° C./min for a test piece having a length of 50 mm and a width of 10 mm, and the temperature range is 30 to 30 to min. It is a value calculated by dividing the amount of change in length at 80 ° C. by the amount of change in temperature. A thermomechanical analyzer can be used for measuring the amount of change in length, and for example, TMA / SS6100 manufactured by Seiko Instruments Inc. can be used.

Further, the laminate produced by the method for producing the laminate of the present embodiment exhibits excellent durability because the fine fibrous cellulose-containing sheet is covered with the resin component. In the present specification, the durability of the laminate is good because the appearance of the laminate is observed after being immersed in warm water, the appearance of the laminate is not changed, and the interlayer adhesion is maintained. Can be determined to be. Specifically, after immersing the laminate in warm water having a temperature of 60 ° C. for 24 hours, the appearance of the laminate is observed. Even when the laminate obtained in the present embodiment is immersed in warm water for a long time, expansion of the laminate is not observed, and the occurrence of delamination and the like is suppressed.

The laminate produced by the method for producing a laminate of the present embodiment is also excellent in durability at high temperatures. In the present specification, the durability of the laminate under high temperature is such that the appearance of the laminate is observed after being exposed to high temperature, the appearance of the laminate is not changed, and the interlayer adhesion is maintained. It can be judged that it is good. Specifically, the laminated body is allowed to stand in a constant temperature bath at a temperature of 110 ° C. for 720 hours in an air atmosphere, and then the appearance of the laminated body is observed. Even when the laminate obtained in the present embodiment is exposed to a high temperature for a long time, no defects are observed in the laminate, and the occurrence of delamination and the like is suppressed.

The laminate produced by the method for producing a laminate of the present embodiment is also excellent in transparency and its yellowness is suppressed to a low level. Specifically, the haze of the laminated body is preferably 20% or less, more preferably 10% or less, and further preferably 5% or less. The yellowness (YI value) of the laminate is preferably 40 or less, more preferably 30 or less, and even more preferably 20 or less. The haze of the laminated body is a value measured using a haze meter in accordance with "JIS K 7136: 2000". The yellowness (YI value) of the laminate is a value measured using a color meter in accordance with JIS K 7373: 2006.

The total light transmittance of the laminated body is preferably 20% or more, more preferably 40% or more, further preferably 60% or more, still more preferably 80% or more. It is particularly preferably 85% or more. The upper limit of the total light transmittance of the laminated body is not particularly limited and may be 100%, for example. Here, the total light transmittance of the laminated body is a value measured using, for example, JIS K 7361-1: 1997 and using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute).

As described above, when the fine fibrous cellulose-containing sheet 10 is arranged in the mold 50, the arrangement position of the fine fibrous cellulose-containing sheet in the obtained laminate 100 is obtained by appropriately adjusting the fixing position thereof. Can be controlled. That is, the uneven distribution region of the fine fibrous cellulose in the laminate 100 can be adjusted. In the production method of the present embodiment, the fine fibrous cellulose-containing sheet 10 may be arranged on the central surface in the thickness direction of the void portion formed by the mold 50. In this case, the obtained laminated body 100 has a structure as shown in FIG. 2A, and the cross section of the laminated body 100 has the structure shown in FIG. In FIGS. 2 and 3, the laminate 100 has a fine fibrous cellulose-containing sheet 10 and a resin layer 30, and the fine fibrous cellulose-containing sheet 10 is embedded in the resin layer 30. FIG. 3A is a cross-sectional view of the laminated body 100, and shows a layer structure in a cross section parallel to the length direction (direction L in FIG. 2A). FIG. 3B is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the width direction (direction W in FIG. 2A). The cross section is a surface that passes through the center point of the laminated body 100, and is a surface that appears when cut in the thickness direction. Moreover, since the figure explaining the structure of the laminated body in this specification is drawn so that the structure of each layer is easy to understand, the thickness and the thickness ratio of each layer are not necessarily the same as the structure in the actual laminated body.

In the production method of the present embodiment, it is preferable to dispose the fine fibrous cellulose-containing sheet 10 along the mold plane of the mold 50. For example, the fine fibrous cellulose-containing sheet 10 may be disposed at a predetermined distance from the mold plane so as not to come into contact with the mold plane. In this case, since the molten resin also flows between the fine fibrous cellulose-containing sheet 10 and the mold 50, the cross section of the obtained laminate 100 has a configuration as shown in FIG. FIG. 4A is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the length direction. FIG. 4B is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the width direction.

When the fine fibrous cellulose-containing sheet 10 is arranged along the mold plane of the mold 50, another sheet is arranged on the mold plane, and the fine fibrous cellulose-containing sheet 10 is arranged on the other sheet. May be arranged. In this case, the cross section of the obtained laminated body 100 has a configuration as shown in FIG. In FIG. 5, the fine fibrous cellulose-containing sheet 10 is in a state of being laminated on the resin sheet 20, and the fine fibrous cellulose-containing sheet 10 is arranged inside the laminated body 100 in the thickness direction. FIG. 5A is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the length direction. FIG. 5B is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the width direction.
In the laminate 100 obtained as described above, the fibrous cellulose is unevenly distributed in the non-exposed region in the region near the surface layer in the thickness direction of the laminate. In the present specification, the region near the surface layer in the thickness direction of the laminated body is a region existing in a region from the surface of the laminated body to 30% of the total thickness of the laminated body, and is the exposed outermost surface (laminated body). The area excluding the outermost surface). As described above, by unevenly distributing the fibrous cellulose in the non-exposed region in the region near the surface layer in the thickness direction of the laminate, the flexural modulus of the laminate can be more effectively increased.

Further, when the fine fibrous cellulose-containing sheet 10 is arranged in the mold 50, it is also preferable to arrange a plurality of fine fibrous cellulose-containing sheets 10 in the mold 50. For example, the fine fibrous cellulose-containing sheet 10 can be arranged so as to face each other along both sides of the inner wall (mold plane) of the mold. In this case, at least a part of the molten resin will be filled between the opposing fine fibrous cellulose-containing sheets. A part of the molten resin may be filled between the fine fibrous cellulose-containing sheet and the inner wall of the mold (mold plane). The cross section of the laminated body 100 obtained in this manner has a configuration as shown in FIG. FIG. 6A is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the length direction. FIG. 6B is a cross-sectional view of the laminated body 100 and shows a layer structure in a cross section parallel to the width direction. It is preferable that the fine fibrous cellulose-containing sheets are evenly arranged on one surface side and the other surface side of the laminate. "The laminated body is evenly arranged on one surface side and the other surface side" means that the laminated body is arranged substantially symmetrically with respect to the center line that divides the laminated body into two in the thickness direction. In such a laminated body, it is possible to suppress the variation in the strength of the laminated body, and it is possible to suppress the occurrence of warpage in the laminated body. When evaluating the warp of the laminated body, after allowing the laminated body to stand in an environment of a temperature of 23 ° C. and a relative humidity of 50% for 24 hours, the laminated body was observed, and no curvature was observed in the laminated body. When the shape immediately after production is maintained, the occurrence of warpage is suppressed and it can be judged to be good.

Further, when a plurality of fine fibrous cellulose-containing sheets 10 are arranged so as to face each other along both surfaces of the inner wall of the mold (mold plane), other sheets are arranged on the plane of each mold. Then, the fine fibrous cellulose-containing sheet 10 may be arranged on the sheet. The cross section of the laminated body 100 obtained in this manner has a configuration as shown in FIG. FIG. 7A is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the length direction. FIG. 7B is a cross-sectional view of the laminated body 100 and shows a layer structure in a cross section parallel to the width direction. In this way, by arranging the fibrous cellulose-containing sheets in the non-exposed region in the region near the surface layer in the thickness direction of the laminate so as to face each other, the flexural modulus of the laminate can be more effectively increased. Further, it is possible to suppress the occurrence of warpage in the laminated body.

As shown in FIGS. 5 and 7, when the fine fibrous cellulose sheet 10 is arranged in the mold 50, the fine fibrous cellulose sheet 10 is placed on the inner wall of the mold (mold) via another sheet. It may be fixed to a flat surface). In this case, as the other sheet, a resin sheet, a metal sheet and the like can be preferably exemplified. Above all, the other sheet is preferably a resin sheet. That is, it is preferable that the fine fibrous cellulose sheet 10 is fixed to the inner wall of the mold 50 via the resin sheet 20. The resin constituting the resin sheet is not particularly limited, and examples thereof include a polycarbonate resin, a polyolefin resin, a polyimide resin, a polystyrene resin, and an acrylic resin. Among them, the resin constituting the resin sheet is preferably at least one selected from a polycarbonate resin and an acrylic resin, and is particularly preferably a polycarbonate resin. The resin constituting the resin sheet may be an alloy resin containing a polycarbonate resin and an acrylic resin.

The resin sheet 20 as described above may exist in a non-contact state with the fine fibrous cellulose-containing sheet 10. For example, the resin sheet 20 is arranged so as to face each other on both sides of the inner wall (mold plane) of the mold, while the fine fibrous cellulose-containing sheet 10 is centered in the thickness direction of the void portion formed by the mold 50. It may be arranged on a surface. In this case, the cross section of the obtained laminated body 100 has a configuration as shown in FIG. FIG. 8A is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the length direction. FIG. 8B is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the width direction.

In the laminate 100 having the structure shown in FIGS. 2 to 8, the edge of the fine fibrous cellulose-containing sheet 10 is covered with a resin component derived from the molten resin injected into the mold. .. In the present specification, the edge of the fine fibrous cellulose-containing sheet 10 is the end face of the fine fibrous cellulose-containing sheet 10, the outer peripheral edge of the fine fibrous cellulose-containing sheet 10, and is shaded in FIG. 2 (b). This is the area indicated by. In the laminate obtained in the present embodiment, since the entire region of the edge of the fine fibrous cellulose-containing sheet is covered with the resin component derived from the molten resin, the laminate has a high elastic modulus and low linear heat. In addition to having an expansion coefficient, it can exhibit excellent durability.

The method for producing the laminate of the present embodiment may further include a step of coating the exposed portion of the fine fibrous cellulose-containing sheet 10 after the step of solidifying the molten resin. In such a case, before the coating step, at least a part of the edge of the fine fibrous cellulose-containing sheet 10 is not covered with the resin component derived from the molten resin injected into the mold. , Exposed from the laminate 100. Therefore, after the laminate 100 is formed and the mold is removed, the edge of the fine fibrous cellulose-containing sheet 10 and the exposed edge is covered with a resin component to form the fine fibrous cellulose. A laminated body in which the containing sheet 10 is wrapped with the resin component may be obtained. The coating step may be a step of heat-sealing the exposed portion of the fine fibrous cellulose-containing sheet 10 using a resin component, or a step of applying a molten resin to the exposed portion of the fine fibrous cellulose-containing sheet 10. It may be. The resin component used in the coating step may be the same type of resin as the molten resin injected in the injection molding step, or may be a different type of resin. The cross section of the laminated body 100 obtained through such a step has a configuration as shown in FIG. FIG. 9A is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the length direction. FIG. 9B is a cross-sectional view of the laminated body 100, showing a layer structure in a cross section parallel to the width direction. In FIG. 9B, the edge of the laminate 100 is covered with the coating resin 35 (cover resin). As a result, the edge of the fine fibrous cellulose-containing sheet 10 is also coated with the coating resin 35 (cover resin). In this way, by coating the fine fibrous cellulose-containing sheet 10 in the post-process, it is possible to bring the sheet containing the fibrous cellulose into a state of being covered with the resin component.

(Laminated body)
The present embodiment may relate to a laminate produced by the method for producing a laminate as described above. The laminate has at least a layer containing fibrous cellulose having a fiber width of 1000 nm or less (also referred to as a fine fibrous cellulose-containing layer or a fine fibrous cellulose-containing sheet) and a resin layer. Then, in the laminated body, the fine fibrous cellulose-containing layer is covered with the resin component. In the laminate obtained in the present embodiment, since the entire region of the fine fibrous cellulose-containing layer is covered with the resin component derived from the molten resin, the laminate has a high elastic modulus and a low coefficient of linear thermal expansion. In addition to having, it can exhibit excellent durability.

It can be confirmed as follows that the laminate is manufactured by the manufacturing method described in the present specification.
First, in the manufacturing process of the laminate, the layer containing the fibrous cellulose having a fiber width of 1000 nm or less was arranged in the mold. The morphology of the fiber layer portion of the laminate was observed with an electron microscope or the like. This can be confirmed by detecting the presence of fibers having a fiber width of 1000 nm or less and analyzing the chemical composition with a Fourier transform infrared spectrophotometer or the like to detect a spectrum derived from cellulose. In addition, the fact that the layer containing fibrous cellulose having a fiber width of 1000 nm or less is covered with the resin component means that the chemical composition of the terminal portion of the laminate is analyzed by a Fourier transform infrared spectrophotometer or the like. , It can be confirmed by detecting the spectrum derived from the resin component. Further, in the manufacturing process of the laminated body, the step of injecting the molten resin into the mold and the step of solidifying the molten resin include the presence of an injection gate in the laminated body and the terminal portion of the laminated body. It can be confirmed from the shape of the above, the smoothness of the surface of the laminate, the distribution of residual stress, and the like.

In the laminated body, the area of the maximum surface of the laminated body is preferably larger than the area of the maximum surface of the fine fibrous cellulose-containing sheet. As a result, the fine fibrous cellulose-containing sheet is in a state of being embedded in the laminate. As a result, more excellent durability can be exhibited. The area of the maximum surface of the laminated body is a value calculated from the length × width of the laminated body, and the area of the maximum surface of the fine fibrous cellulose-containing sheet is calculated from the length × width of the sheet. The value. As a matter of course, the thickness of the fine fibrous cellulose-containing sheet is thinner than the total thickness of the laminate.

In the laminate, the fine fibrous cellulose-containing layer may be present at the center of the laminate in the thickness direction. Further, the fine fibrous cellulose-containing layer may be present in a region near the surface layer in the thickness direction of the laminate. The region near the surface layer in the thickness direction of the laminated body is a region existing from the surface of the laminated body to 30% of the total thickness of the laminated body, and is a region excluding the exposed outermost surface. As described above, by unevenly distributing the fibrous cellulose in the non-exposed region in the region near the surface layer in the thickness direction of the laminate, the flexural modulus of the laminate can be more effectively increased. Further, two or more fine fibrous cellulose-containing layers may be present in the laminate. For example, it is preferable that two fine fibrous cellulose-containing layers are present in the front surface side and the back surface side in the vicinity of the surface layer, respectively. In this way, by evenly presenting the fine fibrous cellulose on one surface side and the other surface side of the laminate, it is possible to suppress the variation in the strength of the laminate, and the laminate is warped. It can be suppressed.

The laminate may have a layer containing fibrous cellulose having a fiber width of 1000 nm or less, and a layer made of a resin sheet in addition to the resin layer. Further, the laminated body may have an arbitrary layer as described later. In the laminated body, each layer may be provided with only one layer, or may be provided with two or more layers. When the laminated body has a layer made of a resin sheet or the like, the durability and impact resistance of the laminated body can be more effectively enhanced.

The overall thickness of the laminate is preferably 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. Further, the upper limit of the total thickness of the laminated body is not particularly limited, and may be, for example, 10 mm or less.

(Fine fibrous cellulose-containing layer)
The layer containing fine fibrous cellulose (also referred to as a fine fibrous cellulose-containing layer) contains fibrous cellulose (fine fibrous cellulose) having a fiber width of 1000 nm or less. The fiber width of the fibrous cellulose is preferably 100 nm or less, more preferably 8 nm or less. As a result, the transparency of the fine fibrous cellulose-containing layer is enhanced, and the strength of the laminate is increased when the laminate is formed.

The fiber width of the fibrous cellulose can be measured, for example, by observation with an electron microscope. The average fiber width of the fibrous cellulose is, for example, 1000 nm or less. The average fiber width of the fibrous cellulose is, for example, 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, further preferably 2 nm or more and 50 nm or less, and 2 nm or more and 10 nm or less. Especially preferable. By setting the average fiber width of the fibrous cellulose to 2 nm or more, it is possible to suppress the dissolution of the fibrous cellulose as a cellulose molecule in water, and to make it easier to exhibit the effects of the fibrous cellulose on improving strength, rigidity, and dimensional stability. it can. The fibrous cellulose is, for example, monofibrous cellulose. The average fiber width of the fibrous cellulose is preferably within the above range, but the fine fibrous cellulose-containing layer may contain coarse fibers having a fiber width of more than 1000 nm.

The average fiber width of fibrous cellulose is measured, for example, using an electron microscope as follows. First, an aqueous suspension of fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and this suspension is cast on a hydrophilized carbon film-coated grid to prepare a sample for TEM observation. And. If it contains wide fibers, an SEM image of the surface cast on the glass may be observed. Next, observation is performed using an electron microscope image at a magnification of 1000 times, 5000 times, 10000 times, or 50,000 times depending on the width of the fiber to be observed. 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 observation images of surface portions that do not overlap each other are obtained. Next, for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. As a result, at least 20 fibers × 2 × 3 = 120 fibers are read. Then, the average value of the read fiber widths is taken as the average fiber width of the fibrous cellulose.

The fiber length of the 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 further preferably 0.1 μm or more and 600 μm or less. preferable. By setting the fiber length within the above range, destruction of the crystal region of the fibrous cellulose can be suppressed. It is also possible to set the slurry viscosity of the fibrous cellulose in an appropriate range. The fiber length of the fibrous cellulose can be obtained by, for example, image analysis by TEM, SEM, or AFM.

The fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the 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, for example, preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. As a result, even better 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 axial ratio (fiber length / fiber width) of the fibrous cellulose is not particularly limited, but is preferably 20 or more and 10000 or less, and more preferably 50 or more and 1000 or less. By setting the axial ratio to the above lower limit value or more, it is easy to form a sheet containing fine fibrous cellulose. In addition, sufficient viscosity can be easily obtained when the solvent dispersion is produced. By setting the axial ratio to the above upper limit value or less, for example, when fibrous cellulose is treated as an aqueous dispersion, it is preferable in that handling such as dilution becomes easy.

The fibrous cellulose in the present embodiment has, for example, both a crystalline region and a non-crystalline region. In particular, fine fibrous cellulose having both a crystalline region and a non-crystalline region and having a high axial ratio is realized by a method for producing fine fibrous cellulose, which will be described later.

The fibrous cellulose may have at least one of an ionic substituent and a nonionic substituent. From the viewpoint of improving the dispersibility of the fibrous cellulose in the dispersion medium and increasing the defibration efficiency in the defibration treatment, it is more preferable that the fibrous cellulose has an ionic substituent. The ionic substituent can include, for example, either one or both of an anionic group and a cationic group. Further, as the nonionic substituent, for example, an alkyl group and an acyl group can be included. In this embodiment, it is particularly preferable to have an anionic group as the ionic substituent. The fibrous cellulose may not be subjected to a treatment for introducing an ionic substituent.

Examples of the anionic group as an ionic substituent include a phosphate group or a substituent derived from a phosphorusoxo acid group (sometimes referred to simply as a phosphorusoxo acid group), a carboxy group or a substituent derived from a carboxy group (simply a carboxy group). It is preferably at least one selected from a sulfone group or a substituent derived from a sulfone group (sometimes simply referred to as a sulfone group). Among them, the anionic group is more preferably at least one selected from a phosphorus oxo acid group and a carboxy group, and particularly preferably a phosphorus oxo acid group. By introducing a phosphorous acid group such as a phosphoric acid group or a phosphorous acid group as an anionic group, the dispersibility of the fibrous cellulose can be further enhanced even under alkaline or acidic conditions, for example, and the fibrous cellulose is in the form of fine fibers. The strength of the cellulose-containing sheet can be increased, and as a result, the strength of the laminate can be increased. Further, by introducing a phosphorus oxo acid group such as a phosphoric acid group or a phosphorous acid group, the transparency of the obtained laminate can be more effectively enhanced and yellowing can be suppressed.

The phosphate group or the substituent derived from the phosphorus oxo acid group is, for example, a substituent represented by the following formula (1). The phosphoroxoic acid group is, for example, a divalent functional group obtained by removing a hydroxy group from phosphoric acid. Specifically, it is a group represented by _{−PO 3} H _2. Substituents derived from a phosphorus oxo acid group include substituents such as a salt of a phosphorus oxo acid group and a phosphorus oxo acid ester group. The substituent derived from the phosphoric acid group may be contained in the fibrous cellulose as a group in which the phosphoric acid group is condensed (for example, a pyrophosphate group). Further, the phosphorous acid group may be, for example, a phosphorous acid group (phosphonic acid group), and the substituent derived from the phosphorous acid group is a salt of the phosphorous acid group, a phosphorous acid ester group, or the like. May be good.

In the formula (1), a, b and n are natural numbers, and m is an arbitrary number (where a = b × m). Of α ¹ , α ² , ..., α ⁿ and α', a are O ⁻ , and the rest are either R or OR. It is also possible that all of each α ⁿ and α'are O ^−. 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, and an unsaturated-branched chain hydrocarbon, respectively. A hydrogen group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. Further, in the formula (1), n is preferably 1.

Examples of the saturated-linear hydrocarbon group include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an n-butyl group and the like. Examples of the saturated-branched chain hydrocarbon group include an i-propyl group and a t-butyl group, but are not particularly limited. Examples of the saturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentyl group, a cyclohexyl group and the like. Examples of the unsaturated-linear hydrocarbon group include a vinyl group, an allyl group and the like, but are not particularly limited. Examples of the unsaturated-branched chain hydrocarbon group include an i-propenyl group and a 3-butenyl group, but the group is not particularly limited. Examples of the unsaturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentenyl group, a cyclohexenyl group and the like. Examples of the aromatic group include a phenyl group and a naphthyl group, but are not particularly limited.

Further, as the inducing group in R, a functional group in which at least one of functional groups such as a carboxy group, a hydroxy group, or an amino group is added or substituted with respect to the main chain or side chain of the above-mentioned various hydrocarbon groups. The group is mentioned, but is not particularly limited. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, and more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R to the above range, the molecular weight of the phosphorus oxo acid group can be set to an appropriate range, the penetration into the fiber raw material is facilitated, and the yield of the fine cellulose fiber is increased. You can also do it.

β ^{b +} is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include aliphatic ammonium or aromatic ammonium, and examples of monovalent or higher valent cations composed of inorganic substances include ions of alkali metals such as sodium, potassium, and lithium. Examples thereof include cations of divalent metals such as calcium and magnesium, hydrogen ions, and the like, but the present invention is not particularly limited. These may be applied alone or in combination of two or more. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing β is heated and is easily industrially used, but is not particularly limited. Note that β ^{b +} may be an organic onium ion.

The amount of the ionic substituent introduced into the fibrous cellulose is, for example, 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol / g per 1 g (mass) of the fibrous cellulose. It is more preferably / g or more, and particularly preferably 1.00 mmol / g or more. The amount of the ionic substituent introduced into the fibrous cellulose is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less per 1 g (mass) of the fibrous cellulose, for example, 3 It is more preferably .50 mmol / g or less, and particularly preferably 3.00 mmol / g or less. By setting the amount of the ionic substituent introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fibrous cellulose. Further, by setting the amount of the ionic substituent to be introduced within the above range, good characteristics can be exhibited in various applications such as a thickener for fibrous cellulose. Here, the denominator in the unit mmol / g indicates the mass of fibrous cellulose when the counter ion of the ionic substituent is a hydrogen ion (H ^+).

The amount of the ionic substituent introduced into the fibrous cellulose can be measured by, for example, a neutralization titration method. In the measurement by the neutralization titration method, the introduction amount is measured by determining the change in pH while adding an alkali such as an aqueous sodium hydroxide solution to the obtained slurry containing fibrous cellulose.

FIG. 10 is a graph showing the relationship between the amount of NaOH added dropwise and the pH of the fibrous cellulose-containing slurry having a phosphorus oxo acid group. The amount of the phosphorus oxo acid group introduced into the fibrous cellulose is measured, for example, as follows.
First, the slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. If necessary, the defibration treatment similar to the defibration treatment step described later may be performed on the measurement target before the treatment with the strongly acidic ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 10 is obtained. The titration curve shown in the upper part of FIG. 10 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 10 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, two points are confirmed in which the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point. The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociating acid of the fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the first end point to the second end point. The amount is equal to the amount of the second dissociating acid of the fibrous cellulose contained in the slurry used for the titration, and the amount of alkali required from the start to the second end point of the titration is the fibrous cellulose contained in the slurry used for the titration. Is equal to the total amount of dissociated acid. Then, the value obtained by dividing the amount of alkali required from the start to the first end point by the solid content (g) in the slurry to be titrated is the amount of phosphorus oxo acid group introduced (mmol / g). The amount of phosphorus oxo acid group introduced (or the amount of phosphorus oxo acid group) simply means the amount of the first dissociated acid.
In FIG. 10, the region from the start of titration to the first end point is referred to as a first region, and the region from the first end point to the second end point is referred to as a second region. For example, when the phosphoric acid group is a phosphoric acid group and the phosphoric acid group causes condensation, the amount of weakly acidic groups in the phosphoric acid group (also referred to as the second dissociated acid amount in the present specification) is apparently It decreases, 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 in the phosphorus oxo acid group (also referred to as the first dissociated acid amount in the present specification) matches the amount of phosphorus atoms regardless of the presence or absence of condensation. When the phosphorous acid group is a phosphorous acid group, the weakly acidic group does not exist in the phosphorous acid group, so that the amount of alkali required for the second region is reduced or the amount of alkali required for the second region is reduced. May be zero. In this case, there is only one point on the titration curve where the pH increment is maximized.

Since the denominator of the above-mentioned phosphorus oxo acid group introduction amount (mmol / g) indicates the mass of the acid-type fibrous cellulose, the phosphorus oxo acid group amount of the acid-type fibrous cellulose (hereinafter referred to as the phosphorus oxo acid group amount). (Called (acid type))). On the other hand, when the counterion of the phosphorus oxo acid group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of fibrous cellulose when the cation C is a counterion. This makes it possible to determine the amount of phosphorus oxo acid groups (hereinafter, the amount of phosphorus oxo acid groups (C type)) possessed by the fibrous cellulose in which the cation C is a counterion.
That is, it is calculated by the following formula.
Phosphoric acid group amount (C type) = Phosphoric acid group amount (acid type) / {1+ (W-1) x A / 1000}
A [mmol / g]: Total amount of anions derived from the phosphoric acid group of the fibrous cellulose (total amount of dissociated acid of the phosphoric acid group)
W: Formula amount per valence of cation C (for example, Na is 23, Al is 9)

In the measurement of the amount of phosphorus oxo acid groups by the titration method, accurate values such as when the amount of one drop of sodium hydroxide aqueous solution is too large or when the titration interval is too short, the amount of phosphorus oxo acid groups is lower than the original amount can be obtained. Sometimes not. As an appropriate dropping amount and titration interval, for example, it is desirable to titrate 10 to 50 μL of a 0.1 N sodium hydroxide aqueous solution every 5 to 30 seconds. Further, in order to eliminate the influence of carbon dioxide dissolved in the fibrous cellulose-containing slurry, for example, it is desirable to measure while blowing an inert gas such as nitrogen gas into the slurry from 15 minutes before the start of titration to the end of titration.

FIG. 11 is a graph showing the relationship between the amount of NaOH added dropwise to the slurry containing the first cellulose fiber having a carboxy group and the pH. The amount of the carboxy group introduced into the first cellulose fiber is measured, for example, as follows.
First, the slurry containing the first cellulose fiber is treated with a strongly acidic ion exchange resin. If necessary, the defibration treatment similar to the defibration treatment step described later may be performed on the measurement target before the treatment with the strongly acidic ion exchange resin.
Next, the change in pH is observed while adding an aqueous sodium hydroxide solution, and a titration curve as shown in the upper part of FIG. 11 is obtained. The titration curve shown in the upper part of FIG. 11 plots the measured pH with respect to the amount of alkali added, and the titration curve shown in the lower part of FIG. 11 plots the pH with respect to the amount of alkali added. The increment (differential value) (1 / mmol) is plotted. In this neutralization titration, in the curve plotting the measured pH with respect to the amount of alkali added, one point was confirmed where the increment (differential value of pH with respect to the amount of alkali dropped) became maximum, and this maximum point was the first. Called one end point. Here, the region from the start of titration to the first end point in FIG. 11 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the slurry used for titration. Then, by dividing the amount of alkali (mmol) required in the first region of the titration curve by the solid content (g) in the slurry containing the first cellulose fiber to be titrated, the amount of carboxy group introduced (the amount of carboxy group introduced (mmolation group) mmol / g) is calculated.
The above-mentioned amount of carboxy group introduced (mmol / g) is the amount of substituents per 1 g of mass of the first cellulose fiber when the ^{counterion of the carboxy group is hydrogen ion (H +) (hereinafter, the amount of carboxy group).} (Called (acid type)).

Since the denominator of the above-mentioned carboxy group introduction amount (mmol / g) is the mass of the acid type fibrous cellulose, the carboxy group amount of the acid type fibrous cellulose (hereinafter, the carboxy group amount (acid type)). ) Is shown. On the other hand, when the counterion of the carboxy group is replaced with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of fibrous cellulose when the cation C is a counterion. Then, the amount of carboxy groups (hereinafter, the amount of carboxy groups (C type)) possessed by the fibrous cellulose in which the cation C is a counter ion can be determined.
That is, it is calculated by the following formula.
Carboxy group amount (C type) = carboxy group amount (acid type) / {1+ (W-1) × (carboxy group amount (acid type)) / 1000}
W: Formula amount per valence of cation C (for example, Na is 23, Al is 9)

In the measurement of the amount of substituents by the titration method, if the titration interval of the sodium hydroxide aqueous solution is too short, the amount of substituents may be lower than the original amount. Therefore, an appropriate titration interval, for example, 0.1N sodium hydroxide aqueous solution It is desirable to titrate 10 to 50 μL each in 5 to 30 seconds.

The content of the fibrous cellulose is preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 30% by mass or more, based on the total mass of the fine fibrous cellulose-containing layer. More preferably, it is more preferably 50% by mass or more, and particularly preferably 70% by mass or more. Further, the content of the fibrous cellulose may be 100% by mass with respect to the total mass of the fine fibrous cellulose-containing layer. That is, the fine fibrous cellulose-containing layer may be a layer made of fine fibrous cellulose.

The thickness of one layer of the fine fibrous cellulose-containing layer is preferably 20 μm or more, more preferably 40 μm or more, and further preferably 60 μm or more. The thickness of one layer of the fine fibrous cellulose-containing layer is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 250 μm or less. Even when two or more fine fibrous cellulose-containing layers are provided in the laminated body, the thickness of each layer is preferably within the above range. By setting the thickness of the fine fibrous cellulose-containing layer within the above range, it becomes easy to obtain the strength for reinforcing the laminate. In addition, the production efficiency of the fine fibrous cellulose-containing layer can be increased. Here, the thickness of one layer of the fine fibrous cellulose-containing layer can be measured by cutting out a cross section of the laminate with, for example, Ultra Microtome UC-7 (manufactured by JEOL Ltd.) and observing the cross section with an electron microscope. ..

The density of the fine fibrous cellulose-containing layer ^{is preferably 0.5 g / cm 3} or more, more preferably 1.0 g / cm ³ or more, and ^{further preferably 1.2 g / cm 3} or more. , 1.4 g / cm ³ or more is particularly preferable. The upper limit of the density of the fine fibrous cellulose-containing layer is not particularly limited, and may be, for example, 3.0 g / cm ³ . By setting the density of the fine fibrous cellulose-containing layer within the above range, it becomes easy to obtain the strength for reinforcing the laminate. The density of the fine fibrous cellulose-containing layer is a value calculated by dividing the basis weight of the layer by the thickness.

The basis weight of one layer of the fine fibrous cellulose-containing layer ^{is preferably 10 g / m 2} or more, more preferably 30 g / m ² or more, further preferably 50 g / m ² or more, and 100 g. It is particularly preferable that it is / m ^{2 or more.} The basis weight of one layer of the fine fibrous cellulose-containing layer ^{is preferably 1500 g / m 2} or less, more preferably 750 g / m ² or less, and further preferably 500 g / m ² or less. .. When a plurality of fine fibrous cellulose-containing layers are provided, the total basis weight of the fine fibrous cellulose-containing layers ^{is preferably 50 g / m 2} or more, and preferably 100 g / m ² or more. More preferred. The total basis weight of the fine fibrous cellulose-containing layer ^{is preferably 3000 g / m 2} or less, more preferably 1500 g / m ² or less, and even more preferably 1000 g / m ² or less. The basis weight of one layer of the fine fibrous cellulose-containing layer may be 150 g / m ² or more, or 200 g / m ² or more. Further, the total basis weight of the fine fibrous cellulose-containing layer may be 300 g / m ² or more, or 400 g / m ² or more. By increasing the basis weight of the fine fibrous cellulose-containing layer, the bending elasticity of the laminate can be increased more effectively, and the linear thermal expansion coefficient of the laminate can be further reduced. Here, the basis weight of the fine fibrous cellulose-containing layer is a value calculated according to the following method after cutting with, for example, Ultra Microtome UC-7 (manufactured by JEOL Ltd.) so that only the fiber layer remains. The weight of the fiber layer cut to a size of 2 cm square or more is measured, and this weight is divided by the area of the cut fiber layer to calculate the basis weight of the fiber layer.

The haze of the fine fibrous cellulose-containing layer is, for example, preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less. On the other hand, the lower limit of the haze of the fine fibrous cellulose-containing layer is not particularly limited and may be, for example, 0%. Here, the haze of the fine fibrous cellulose-containing layer is cut by, for example, Ultra Microtome UC-7 (manufactured by JEOL Ltd.) so that only the fine fibrous cellulose-containing layer remains, and conforms to JIS K 7136: 2000, and is a haze meter. It is a value measured using (HM-150, manufactured by Murakami Color Technology Research Institute).

The total light transmittance of the fine fibrous cellulose-containing layer is, for example, preferably 85% or more, more preferably 90% or more, and further preferably 91% or more. On the other hand, the upper limit of the total light transmittance of the fine fibrous cellulose-containing layer is not particularly limited and may be, for example, 100%. Here, the total light transmittance of the fine fibrous cellulose-containing layer is cut by, for example, Ultra Microtome UC-7 (manufactured by JEOL Ltd.) so that only the fine fibrous cellulose-containing layer remains, and JIS K 7361-1: 1997. It is a value measured using a haze meter (HM-150 manufactured by Murakami Color Technology Research Institute) in accordance with the above.

The fine fibrous cellulose-containing layer may contain an arbitrary component in addition to the fine fibrous cellulose. Examples of the optional component include hydrophilic polymers, hydrophilic low molecules, organic ions and the like. In addition, the fine fibrous cellulose-containing layer has optional components such as a surfactant, a coupling agent, an inorganic layered compound, an inorganic compound, a leveling agent, an antiseptic, an antifoaming agent, an organic particle, a lubricant, and an antistatic agent. It may contain one or more selected from UV protection agents, dyes, pigments, stabilizers, magnetic powders, orientation promoters, plastics, dispersants, and cross-linking agents.

The hydrophilic polymer is preferably a hydrophilic oxygen-containing organic compound (excluding the above-mentioned cellulose fibers), and examples of the oxygen-containing organic compound include polyethylene glycol, polyethylene oxide, casein, dextrin, starch, and modification. Distillate, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), polyvinylpyrrolidone, polyvinylmethyl ether, polyacrylates, acrylic acid alkyl ester copolymer, urethane-based copolymer, cellulose derivative (hydroxyethyl cellulose, carboxy) Ethyl cellulose, carboxymethyl cellulose, etc.) and the like.

The hydrophilic low molecule is preferably a hydrophilic oxygen-containing organic compound, and more preferably a polyhydric alcohol. Examples of the polyhydric alcohol include glycerin, sorbitol, ethylene glycol and the like.

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.

The end of the fine fibrous cellulose-containing layer may be covered with a coating resin (cover resin). Examples of the resin type used for the coating resin include the resin type used for the resin layer.

<Manufacturing process of fine fibrous cellulose>
<Fiber raw material>
Fine fibrous cellulose is produced from a fiber raw material containing cellulose. The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Examples of pulp include wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, but is, for example, broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), and unbleached kraft pulp (UKP). ) And chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), etc. Examples include mechanical pulp. The non-wood pulp is not particularly limited, and examples thereof include cotton-based pulp such as cotton linter and cotton lint, and non-wood pulp such as hemp, straw and bagas. The deinking pulp is not particularly limited, and examples thereof include deinking pulp made from recycled paper. 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, for example, wood pulp and deinked pulp are preferable from the viewpoint of availability. Further, among wood pulp, long fiber fine fibrous cellulose having a large cellulose ratio and a high yield of fine fibrous cellulose during defibration treatment and a large axial ratio with less decomposition of cellulose in the pulp can be obtained. From the viewpoint, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable. When long fiber fine fibrous cellulose having a large axial ratio is used, the viscosity tends to be high.

As the fiber raw material containing cellulose, for example, cellulose contained in ascidians and bacterial cellulose produced by acetic acid bacteria can also be used. Further, instead of the fiber raw material containing cellulose, a fiber formed by a linear nitrogen-containing polysaccharide polymer such as chitin or chitosan can also be used.

<Linoxo acid group introduction process>
The process for producing the fine fibrous cellulose preferably includes a step of introducing a phosphorus oxo acid group. In the phosphorus oxo acid group introduction step, at least one compound (hereinafter, also referred to as “compound A”) selected from compounds capable of introducing a phosphorus oxo acid group by reacting with a hydroxyl group of a fiber raw material containing cellulose is introduced into cellulose. It is a step of acting on a fiber raw material containing. By this step, a phosphorus oxo acid group-introduced fiber can be obtained.

In the phosphorus oxo acid group introduction step according to the present embodiment, the reaction between the fiber raw material containing cellulose and Compound A is carried out in the presence of at least one selected from urea and its derivatives (hereinafter, also referred to as “Compound B”). You may. On the other hand, the reaction of the fiber raw material containing cellulose with the compound A may be carried out in the absence of the compound B.

As an example of the method of allowing the compound A to act on the fiber raw material in the coexistence with the compound B, there is a method of mixing the compound A and the compound B with the fiber raw material in a dry state, a wet state or a slurry state. Of these, since the reaction uniformity is high, it is preferable to use a fiber raw material in a dry state or a wet state, and it is particularly preferable to use a fiber raw material in a dry state. The form of the fiber raw material is not particularly limited, but is preferably cotton-like or thin sheet-like, for example. Examples of the compound A and the compound B include a method of adding the compound A and the compound B to the fiber raw material in the form of a powder or a solution dissolved in a solvent, or in a state of being heated to a melting point or higher and melted. Of these, since the reaction is highly homogeneous, it is preferable to add the mixture in the form of a solution dissolved in a solvent, particularly in the form of an aqueous solution. Further, the compound A and the compound B may be added to the fiber raw material at the same time, may be added separately, or may be added as a mixture. The method for adding the compound A and the compound B is not particularly limited, but when the compound A and the compound B are in the form of a solution, the fiber raw material may be immersed in the solution to absorb the liquid and then taken out, or the fiber raw material may be taken out. The solution may be dropped into the water. Further, the required amounts of compound A and compound B may be added to the fiber raw material, or after the excess amounts of compound A and compound B are added to the fiber raw material, respectively, the surplus compound A and compound B are added by pressing or filtering. It may be removed.

The compound A used in this embodiment may be a compound having a phosphorus atom and capable of forming an ester bond with cellulose, and may be phosphoric acid or a salt thereof, phosphoric acid or a salt thereof, dehydration-condensed phosphoric acid or a salt thereof. Examples thereof include salts and anhydrous phosphoric acid (diphosphorus pentoxide), but the present invention is not particularly limited. As the phosphoric acid, those having various puritys can be used, and for example, 100% phosphoric acid (normal phosphoric acid) or 85% phosphoric acid can be used. Examples of phosphorous acid include 99% phosphorous acid (phosphonic acid). The dehydration-condensed phosphoric acid is one in which two or more molecules of phosphoric acid are condensed by a dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid. Phosphates, phosphorous acids, dehydration-condensed phosphates include phosphoric acid, phosphorous acid or dehydration-condensed phosphoric acid lithium salts, sodium salts, potassium salts, ammonium salts, etc. It can be a sum. Of these, from the viewpoints that the introduction efficiency of phosphoric acid groups is high, the defibration efficiency is more likely to be improved in the defibration process described later, the cost is low, and it is easy to apply industrially, sodium phosphate and sodium phosphate are easy to apply. A salt, a potassium salt of phosphoric acid, or an ammonium salt of phosphoric acid is preferable, and phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, or ammonium dihydrogen phosphate is more preferable.

The amount of compound A added to the fiber raw material is not particularly limited, but for example, 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. It is preferably 100% by mass or less, more preferably 1% by mass or more and 50% by mass or less, and further preferably 2% by mass or more and 30% by mass or less. By setting the amount of phosphorus atoms added to the fiber raw material within the above range, the yield of fine fibrous cellulose can be further improved. On the other hand, by setting the addition amount of phosphorus atoms to the fiber raw material to be equal to or less than the above upper limit value, the effect of improving the yield and the cost can be balanced.

Compound B used in this embodiment is at least one selected from urea and its derivatives as described above. Examples of compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like.
From the viewpoint of improving the uniformity of the reaction, compound B is preferably used as an aqueous solution. Further, from the viewpoint of further improving the uniformity of the reaction, 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 not particularly limited, but is preferably 1% by mass or more and 500% by mass or less, and more preferably 10% by mass or more and 400% by mass or less. It is more preferably 100% by mass or more and 350% by mass or less.

In the reaction between the fiber raw material containing cellulose and compound A, for example, amides or amines may be contained in the reaction system in addition to compound B. 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 phosphorus oxo acid group introduction step, it is preferable to add or mix the compound A or the like to the fiber raw material and then heat-treat the fiber raw material. As the heat treatment temperature, it is preferable to select a temperature at which a phosphorus oxo acid group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. The heat treatment temperature is, for example, 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. In addition, equipment having various heat media can be used for the heat treatment, for example, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, a fluidized layer drying device, and an air stream. A drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, and a high frequency drying device can be used.

In the heat treatment according to the present embodiment, for example, compound A is added to a thin sheet-shaped fiber raw material by a method such as impregnation and then heated, or the fiber raw material and compound A are heated while kneading or stirring with a kneader or the like. Can be adopted. This makes it possible to suppress uneven concentration of the compound A in the fiber raw material and more uniformly introduce the phosphorus oxo acid group onto the surface of the cellulose fiber contained in the fiber raw material. This is because when the water molecules move to the surface of the fiber raw material due to drying, the dissolved compound A is attracted to the water molecules by the surface tension and also moves to the surface of the fiber raw material (that is, the concentration unevenness of the compound A is caused. It is considered that this is due to the fact that it can be suppressed.

Further, the heating device used for the heat treatment always keeps the water content retained by the slurry and the water content generated by the dehydration condensation (phosphate esterification) reaction between the compound A and the hydroxyl group contained in the cellulose or the like in the fiber raw material. It is preferable that the device can be discharged to the outside of the device system. Examples of such a heating device include a ventilation type oven and the like. By constantly discharging the water in the apparatus system, it is possible to suppress the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphate esterification, and also to suppress the acid hydrolysis of the sugar chain in the fiber. it can. Therefore, it is possible to obtain fine fibrous cellulose having a high axial ratio.

The heat treatment time is preferably 1 second or more and 300 minutes or less, more preferably 1 second or more and 1000 seconds or less, and 10 seconds or more and 800 seconds or less after the water is substantially removed from the fiber raw material. Is more preferable. In the present embodiment, the amount of the phosphorus oxo acid group introduced can be within a preferable range by setting the heating temperature and the heating time within an appropriate range.

The phosphorus oxo acid group introduction step may be performed at least once, but may be repeated twice or more. By performing the phosphorus oxo acid group introduction step two or more times, many phosphorus oxo acid groups can be introduced into the fiber raw material. In the present embodiment, as an example of a preferable embodiment, there is a case where the phosphorus oxo acid group introduction step is performed twice.

The amount of the phosphorus oxo acid group introduced into the fiber raw material is, for example, 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol / g / g per 1 g (mass) of fine fibrous cellulose. It is more preferably g or more, and particularly preferably 1.00 mmol / g or more. The amount of the phosphorus oxo acid group introduced into the fiber raw material is preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less per 1 g (mass) of fine fibrous cellulose, for example. It is more preferably 00 mmol / g or less. By setting the amount of the phosphorus oxo 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.

<Carboxylic acid group introduction process>
The carboxy group introduction step has an oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a group derived from carboxylic acid or a derivative thereof, or a group derived from carboxylic acid with respect to the fiber raw material containing cellulose. This is done by treating with an acid anhydride of the compound or a derivative thereof.

The compound having a group derived from a carboxylic acid is not particularly limited, but for example, a dicarboxylic acid compound such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, itaconic acid, citric acid, aconitic acid and the like. Examples include tricarboxylic acid compounds. The derivative of the compound having a group derived from a carboxylic acid is not particularly limited, and examples thereof include an imide of an acid anhydride of a compound having a carboxy group and a derivative of an acid anhydride of a compound having a carboxy group. The imide of the acid anhydride of the compound having a carboxy group is not particularly limited, and examples thereof include an imide of a dicarboxylic acid compound such as maleimide, succinateimide, and phthalateimide.

The acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited, but for example, a dicarboxylic acid compound such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Acid anhydrides can be mentioned. The derivative of the acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited, but for example, a compound having a carboxy group such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, diphenylmaleic acid anhydride and the like. Examples thereof include those in which at least a part of the hydrogen atom of the acid anhydride is substituted with a substituent such as an alkyl group or a phenyl group.

When the TEMPO oxidation treatment is carried out in the carboxy group introduction step, it is preferable to carry out the treatment under conditions of pH 6 or more and 8 or less, for example. Such a treatment is also referred to as a neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH = 6.8), pulp as a fiber raw material, TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl) as a catalyst, and the like. This can be done by adding a nitroxy radical and sodium hypochlorite as a sacrificial reagent. Further, by coexisting with sodium chlorite, the aldehyde generated in the oxidation process can be efficiently oxidized to the carboxy group. Further, the TEMPO oxidation treatment may be carried out under the condition that the pH is 10 or more and 11 or less. Such a treatment is also referred to as an alkaline TEMPO oxidation treatment. The alkaline TEMPO oxidation treatment can be carried out, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a co-catalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. ..

The amount of carboxy group introduced into the fiber raw material varies depending on the type of substituent, but when a carboxy group is introduced by TEMPO oxidation, for example, it is preferably 0.10 mmol / g or more per 1 g (mass) of fine fibrous cellulose. , 0.20 mmol / g or more, more preferably 0.50 mmol / g or more, and particularly preferably 0.90 mmol / g or more. Further, it is preferably 2.5 mmol / g or less, more preferably 2.20 mmol / g or less, and further preferably 2.00 mmol / g or less. In addition, when the substituent is a carboxymethyl group, it may be 5.8 mmol / g or less per 1 g (mass) of fine fibrous cellulose.

<Washing process>
In the method for producing fine fibrous cellulose in the present embodiment, a washing step can be performed on the ionic substituent-introduced fiber, if necessary. The washing step is performed by washing the ionic substituent-introduced fiber with, for example, water or an organic solvent. Further, the cleaning step may be performed after each step described later, and the number of cleanings performed in each cleaning step is not particularly limited.

<Alkaline treatment process>
When producing fine fibrous cellulose, an alkali treatment may be performed on the fiber raw material between the step of introducing an ionic substituent and the step of defibration treatment 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, and may be an inorganic alkaline compound or an organic alkaline compound. In the present embodiment, for example, sodium hydroxide or potassium hydroxide is preferably used as the alkaline compound because of its high versatility. Further, the solvent contained in the alkaline solution may be either water or an organic solvent. Among them, the solvent contained in the alkaline solution is preferably a polar solvent containing water or a polar organic solvent exemplified by alcohol, and more preferably an aqueous solvent containing at least water. As the alkaline solution, for example, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is 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 of the phosphorus oxo acid group-introduced fiber in the alkaline solution in the alkali 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 10,000% by mass or less, for example, with respect to the absolute dry mass of the phosphorus oxo acid group-introduced fiber. Is more preferable.

In order to reduce the amount of the alkaline solution used in the alkali treatment step, the phosphorus oxo acid group introduction fiber may be washed with water or an organic solvent after the ionic substituent introduction step and before the alkali treatment step. After the alkali treatment step and before the defibration treatment step, it is preferable to wash the alkali-treated ionic substituent-introduced fiber with water or an organic solvent from the viewpoint of improving handleability.

<Acid treatment process>
In the case of producing fine fibrous cellulose, the fiber raw material may be subjected to acid treatment between the step of introducing an ionic substituent and the defibration treatment step described later. For example, the ionic substituent introduction step, the acid treatment, the alkali treatment, and the defibration treatment may be performed in this order.

The method of the acid treatment is not particularly limited, and examples thereof include a method of immersing the fiber raw material in an acidic liquid containing an acid. The concentration of the acidic liquid used is not particularly limited, but is preferably, for example, 10% by mass or less, and more preferably 5% by mass or less. The pH of the acidic liquid used is not particularly limited, but is preferably 0 or more and 4 or less, and more preferably 1 or more and 3 or less. As the acid contained in the acidic solution, for example, an inorganic acid, a sulfonic acid, a carboxylic acid or the like can be used. Examples of the inorganic acid include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chloric acid, chloric acid, perchloric acid, phosphoric acid, boric acid and the like. Examples of the sulfonic acid include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like. Examples of the carboxylic acid include formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, tartaric acid and the like. Among these, it is particularly preferable to use hydrochloric acid or sulfuric acid.

The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 90 ° C. or lower. The immersion time in the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 60 minutes or less. The amount of the acid solution used in the acid 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 10,000% by mass or less, for example, with respect to the absolute dry mass of the fiber raw material. Is more preferable.

<Fiber processing>
Fine fibrous cellulose can be obtained by defibrating the ionic substituent-introduced fiber in the defibration treatment step. In the defibration treatment step, for example, a defibration treatment apparatus can be used. The defibrating apparatus is not particularly limited, but for example, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill, a disc type refiner, a conical refiner, and a twin shaft. A kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, or a beater can be used. Among the above-mentioned defibration processing devices, it is more preferable to use a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by crushed media and have less risk of contamination.

In the defibration treatment step, for example, it is preferable to dilute the ionic substituent-introduced fiber with a dispersion medium to form a slurry. As the dispersion medium, one or more selected from water and an organic solvent such as a polar organic solvent can be used. The polar organic solvent is not particularly limited, but for example, alcohols, polyhydric alcohols, ketones, ethers, esters, aprotic polar solvents and the like are preferable. Examples of alcohols include methanol, ethanol, isopropanol, n-butanol, isobutyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, glycerin and the like. Examples of the ketones include acetone, methyl ethyl ketone (MEK) and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-butyl ether, propylene glycol monomethyl ether and the like. Examples of the esters include ethyl acetate, butyl acetate and the like. Examples of the aprotonic polar solvent include dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and the like.

The solid content concentration of the fine fibrous cellulose during the defibration treatment can be appropriately set. Further, the slurry obtained by dispersing the ionic substituent-introduced fiber in a dispersion medium may contain a solid content other than the phosphorus oxo acid group-introduced fiber such as urea having a hydrogen bond property.

<Manufacturing process of fine fibrous cellulose-containing sheet>
As a method for producing a fine fibrous cellulose-containing sheet, for example, a fine fibrous cellulose-containing slurry obtained through the above-mentioned defibration treatment step is made by papermaking or coating (coating) and dried to contain fine fibrous cellulose. A method of forming a sheet can be mentioned.

The slurry used in the process for producing the fine fibrous cellulose-containing sheet preferably further contains, for example, a hydrophilic polymer. As a result, the transparency and mechanical strength of the sheet can be further improved. As the hydrophilic polymer, for example, one kind or two or more kinds selected from those exemplified above can be included.

<Coating process>
In the coating step, for example, a slurry containing fibrous cellulose is applied onto a base material, and the sheet formed by drying the slurry is peeled off from the base material to obtain a sheet. Further, by using a coating device and a long base material, sheets can be continuously produced.

The material of the base material used in the coating process is not particularly limited, but a material having high wettability to the composition (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 film or plate or a metal film or plate is preferable, but is not particularly limited. For example, resin films and plates such as acrylic, polyethylene terephthalate, vinyl chloride, polystyrene, polypropylene, polycarbonate, and polyvinylidene chloride, metal films and plates of aluminum, zinc, copper, and iron plates, and their surfaces are oxidized. , Stainless film or plate, brass film or plate, etc. can be used.

In the coating process, if the viscosity of the slurry is low and it develops on the base material, a dammed frame is fixed on the base material to obtain a sheet with a predetermined thickness and basis weight. You may. The frame for damming is not particularly limited, but it is preferable to select, for example, a frame in which the end portion of the sheet that adheres after drying can be easily peeled off. From this point of view, a resin plate or a metal plate molded is more preferable. In the present embodiment, for example, a resin plate such as an acrylic plate, a polyethylene terephthalate plate, a vinyl chloride plate, a polystyrene plate, a polypropylene plate, a polycarbonate plate, a polyvinylidene chloride plate, or a metal plate such as an aluminum plate, a zinc plate, a copper plate, or an iron plate. , And those whose surfaces are oxidized, stainless steel plates, brass plates and the like can be used.

The coating machine for coating the slurry on the base material is not particularly limited, and for example, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, or the like can be used. A die coater, a curtain coater, and a spray coater are particularly preferable because the thickness of the sheet can be made more uniform.

The slurry temperature and the atmospheric temperature when the slurry is applied to the substrate are not particularly limited, but are preferably, for example, 5 ° C. or higher and 80 ° C. or lower, more preferably 10 ° C. or higher and 60 ° C. or lower, and 15 ° C. It is more preferably 50 ° C. or lower, and particularly preferably 20 ° C. or higher and 40 ° C. or lower. When the coating temperature is equal to or higher than the above lower limit, the slurry can be coated more easily. When the coating temperature is not more than the above upper limit value, the volatilization of the dispersion medium during coating can be suppressed.

As described above, the coating step includes a step of drying the slurry coated on the substrate. The step of drying the slurry is not particularly limited, but is performed by, for example, a non-contact drying method, a method of drying while restraining the sheet, or a combination thereof.

The non-contact drying method is not particularly limited, and for example, a method of heating and drying with hot air, infrared rays, far infrared rays or near infrared rays (heat drying method) or a method of vacuum drying (vacuum drying method) is applied. can do. 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 is not particularly limited, and can be performed using, for example, an infrared device, a far infrared device, or a near infrared device. 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 set to be equal to or higher than the above lower limit value, the dispersion medium can be rapidly volatilized. Further, when the heating temperature is not more than the above upper limit value, it is possible to suppress the cost required for heating and suppress the discoloration of the fibrous cellulose due to heat.

<Papermaking process>
The papermaking process is performed by making a slurry with a paper machine. The paper making machine used in the paper making process is not particularly limited, and examples thereof include a continuous paper making machine of a long net type, a circular net type, an inclined type, etc., or a multi-layer paper making machine combining these. In the papermaking process, a known papermaking method such as hand-making may be adopted.

The papermaking process is performed by filtering and dehydrating the slurry with a wire to obtain a wet paper sheet, and then pressing and drying the sheet. The filter cloth used for filtering and dehydrating the slurry is not particularly limited, but it is more preferable that, for example, fibrous cellulose does not pass through and the filtration rate does not become too slow. Such a filter cloth is not particularly limited, but for example, 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. In the present embodiment, for example, a porous membrane of polytetrafluoroethylene having a pore size of 0.1 μm or more and 20 μm or less, polyethylene terephthalate having a pore size of 0.1 μm or more and 20 μm or less, a polyethylene woven fabric, or the like can be mentioned.

In the sheeting process, a method of producing a sheet from a slurry is, for example, a water-squeezed section in which a slurry containing fibrous cellulose is discharged onto the upper surface of an endless belt and a dispersion medium is squeezed from the discharged slurry to generate a web. It can be done using a manufacturing apparatus with a drying section that dries the web to produce a sheet. 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 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-squeezing section that dries the web to generate a sheet. It has a drying section. 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 embodiment is not particularly limited, and examples thereof include a dehydration method that is usually used in the production of paper. After dehydration with a long net, a circular net, an inclined wire, or the like, dehydration is performed with a roll press. The method is preferred. 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.

Examples of the method of drying the slurry to form a sheet include heat drying, blast drying, vacuum drying and the like. Pressurization may be performed in parallel with drying. The heating temperature is preferably about 50 ° C. to 250 ° C. Within the above temperature range, drying can be completed in a short time, and discoloration and coloring can be suppressed. The pressurization is preferably 0.01 MPa to 5 MPa. Within the above pressure range, the occurrence of cracks and wrinkles can be suppressed, and the density of the fine fibrous cellulose-containing sheet can be increased.

When an arbitrary component is added to the fine fibrous cellulose-containing sheet, it is preferable to uniformly mix the optional component in the fiber slurry to form a fine fibrous cellulose-containing sheet in which the optional component is dispersed. For example, if an oxygen-containing organic compound as an optional component is mixed in the fiber slurry, the drying becomes gentle in the process of forming a sheet by drying a thin layer of the fiber slurry formed by papermaking or coating the fiber slurry. It can be prevented from progressing and causing cracks and wrinkles in the fine fibrous cellulose-containing sheet. As a result, a high-density, transparent film-like fine fibrous cellulose-containing sheet can be formed. The dehydration method used in the papermaking process is not particularly limited, and examples thereof include a dehydration method usually used in the production of paper. Among these, a method of dehydrating with a long net, a circular net, an inclined wire or the like and then further dehydrating with a roll press is preferable. The drying method used in the papermaking process is not particularly limited, and examples thereof include a method used in the production of paper. Among these, a drying method using a cylinder dryer, a Yankee dryer, hot air drying, a near infrared heater, an infrared heater, or the like is more preferable.

(Resin layer)
The resin layer is a layer formed by solidifying the molten resin injected into the mold in the above-mentioned method for producing a laminated body. The resin layer is a layer containing a resin as a main component, and the content of the resin with respect to the total mass of the resin layer is preferably 50% by mass or more, more preferably 70% by mass or more, and 80% by mass. The above is more preferable, and 90% by mass or more is particularly preferable. The content of the resin with respect to the total mass of the resin layer may be 100% by mass, and the resin layer may be a layer made of resin.

The thickness of the resin layer is preferably 1000 μm or more, more preferably 2000 μm or more, and further preferably 3000 μm or more. Further, the upper limit of the total thickness of the resin layer is not particularly limited, and may be, for example, 10 mm or less. When two or more resin layers are provided in the laminated body, the total thickness of each layer is preferably within the above range. By setting the thickness of the resin layer within the above range, it becomes easy to obtain a laminated body having a high elastic modulus. Here, the thickness of the resin layer constituting the laminate is measured by cutting out a cross section of the laminate with, for example, Ultra Microtome UC-7 (manufactured by JEOL Ltd.) and observing the cross section with an electron microscope, a magnifying glass or visually. can do.

In the present embodiment, since the fine fibrous cellulose-containing layer functions as a reinforcing layer of the resin layer, the thickness of the resin layer is preferably thicker than the thickness of the fine fibrous cellulose-containing layer. When the total thickness of the resin layer is P and the total thickness of the fine fibrous cellulose-containing layer is Q, the P / Q value is preferably 1.2 or more, and is 1.5 or more. Is more preferable, and 2.0 or more is further preferable. The P / Q value is preferably 80 or less.

Examples of the resin contained in the resin layer include natural resins and synthetic resins. Examples of the natural resin include rosin resins such as rosin, rosin ester, and hydrogenated rosin ester.

Examples of the synthetic resin include polycarbonate resin, polyolefin resin, polyimide resin, polystyrene resin, acrylic resin and the like. The acrylic resin is preferably at least one selected from polyacrylonitrile and poly (meth) acrylate. Further, since the resin layer is a layer formed by solidifying the molten resin, it is preferable to use a thermoplastic resin as the molten resin. Among them, the synthetic resin is preferably at least one selected from a polycarbonate resin and an acrylic resin, and is particularly preferably a polycarbonate resin. The synthetic resin may be an alloy resin containing a polycarbonate resin and an acrylic resin. When an alloy resin is used, the flexural modulus of the laminate tends to be higher and the linear thermal expansion coefficient tends to be smaller.

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

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.

(Resin sheet)
The laminate may include a resin sheet (a layer made of a resin sheet) in addition to the resin layer. The resin sheet is a sheet that is disposed in the mold together with the fine fibrous cellulose-containing sheet in the manufacturing process of the laminate, and is distinguished from the resin layer formed from the molten resin injected in the injection molding process. However, in the manufacturing process of the laminate, part or all of the resin sheet is melted and compatible with the molten resin injected in the injection molding process, and the interface between the resin layer and the resin sheet is not clear. It may not be there. In such a case, it may be considered that the resin layer includes a layer made of a resin sheet. The resin type constituting the resin layer and the resin sheet may be the same type or different types. When the resin type and the resin sheet constituting the resin layer can be distinguished from each other, the laminated body has a layer made of the resin sheet even if the boundary surface between the resin layer and the resin sheet is not clear. It can be said that it exists.

The resin constituting the resin sheet is not particularly limited, and examples thereof include a polycarbonate resin, a polyolefin resin, a polyimide resin, a polystyrene resin, and an acrylic resin. The acrylic resin is preferably at least one selected from polyacrylonitrile and poly (meth) acrylate. Among them, the resin constituting the resin sheet is preferably at least one selected from a polycarbonate resin and an acrylic resin, and is particularly preferably a polycarbonate resin. The resin constituting the resin sheet may be an alloy resin containing a polycarbonate resin and an acrylic resin.

The thickness of one layer of the layer made of the resin sheet is preferably 50 μm or more, more preferably 100 μm or more, and further preferably 150 μm or more. The thickness of one layer of the resin sheet is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 300 μm or less. Even when two or more layers made of resin sheets are provided in the laminated body, the thickness of each layer is preferably within the above range.

As described above, when the laminated body includes a resin sheet (a layer made of a resin sheet) in addition to the resin layer, the durability of the laminated body can be more effectively enhanced. Further, since a resin sheet suitable for the purpose can be arranged on the surface of the laminate, for example, a resin sheet can be used in order to improve chemical resistance, scratch resistance, and weather resistance.

The flexural modulus of the resin sheet is preferably 0.5 GPa or more, more preferably 1 GPa or more, and further preferably 2 GPa or more. The flexural modulus of the resin sheet is a value measured under the conditions of a distance between fulcrums of 64 mm and a deflection speed of 2 mm / min in accordance with JIS K 7171: 2016. At this time, the test piece is a test piece having a length of 80 mm and a width of 10 mm, and the test temperature is 23 ° C. Then, the flexural modulus is calculated from the slope of the stress / strain curve whose strain is between 0.0005 and 0.0025. A universal material tester can be used as a device for measuring the flexural modulus, and for example, Tencilon RTC-1250A manufactured by A & D Co., Ltd. can be used.

The total light transmittance of the resin sheet is preferably 20% or more, more preferably 40% or more, further preferably 60% or more, still more preferably 80% or more. It is particularly preferably 85% or more. The upper limit of the total light transmittance of the resin sheet is not particularly limited and may be, for example, 100%. Here, the total light transmittance of the resin sheet is a value measured using, for example, JIS K 7361-1: 1997 and using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute).

The coefficient of linear thermal expansion of the resin sheet is preferably 150 ppm / K or less, more preferably 100 ppm / K or less, and even more preferably 75 ppm / K or less. The linear thermal expansion coefficient of the resin sheet is measured by measuring the amount of change in length under the conditions of a test piece having a length of 50 mm and a width of 10 mm in a temperature range of 23 to 90 ° C. and a heating rate of 5 ° C./min, and the temperature range is 30 to 30 to. It is a value calculated by dividing the amount of change in length at 80 ° C. by the amount of change in temperature. A thermomechanical analyzer can be used for measuring the amount of change in length, and for example, TMA / SS6100 manufactured by Seiko Instruments Inc. can be used.

The resin sheet may contain an arbitrary component. Examples of the optional component include fillers, pigments, dyes, ultraviolet absorbers, and the like.

(Arbitrary layer)
The laminate may further include any layer in addition to the above-mentioned layers. Examples of the optional layer include an adhesive layer, an inorganic layer, a hard coat layer, an anti-fog layer, and an anti-glare layer.

<Adhesive layer>
The laminate may further have an adhesive layer, in which case the adhesive layer is preferably provided between the fine fibrous cellulose-containing layer and the resin layer, and the fine fibrous cellulose-containing layer adheres. It may be firmly adhered to the resin layer via the agent layer.

The thickness of one layer of the adhesive layer is, for example, preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 1 μm or more, and particularly preferably 2 μm or more. preferable. The thickness of one layer of the adhesive layer is preferably 100 μm or less, more preferably 50 μm or less, further preferably 30 μm or less, further preferably 20 μm or less, and even more preferably 10 μm or less. Is particularly preferable, and 7 μm or less is most preferable. When the thickness of one layer of the adhesive layer is at least the above lower limit value, sufficient adhesion between the fine fibrous cellulose-containing layer and the resin layer can be obtained. Here, the thickness of the adhesive layer constituting the laminate can be measured by cutting out a cross section of the laminate with, for example, Ultra Microtome UC-7 (manufactured by JEOL Ltd.) and observing the cross section with an electron microscope. ..

The adhesive layer contains (meth) acrylic acid ester polymer, α-olefin copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyurethane, styrene-butadiene copolymer, polyvinyl chloride, and epoxy as main components. Adhesion of one or more selected from resins, melamine resins, silicone resins, polycarbonate resins, polyethylene terephthalate resins, polyethylene naphthalate resins, polyethylene resins, polypropylene resins, polyimide resins, polystyrene resins, casein, natural rubber, and starch It is preferable to include an agent. Here, "as the main component" means that it is 50% by mass or more with respect to the total mass (100% by mass) of the adhesive layer. The (meth) acrylic acid ester polymer includes a polymer obtained by graft-polymerizing a synthetic resin other than the (meth) acrylic resin such as an epoxy resin and a urethane resin, and the (meth) acrylic acid ester and other monomers. Includes copolymers obtained by copolymerizing with.

The adhesive layer may contain an adhesion aid. Examples of the adhesion aid include a compound containing at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an oxazoline group, an amino group and a silanol group, and an organic silicon compound. Among them, the adhesion aid is preferably at least one selected from a compound containing an isocyanate group (isocyanate compound) and an organosilicon compound. Examples of the organosilicon compound include a silane coupling agent condensate and a silane coupling agent.

The content of the adhesion aid is preferably 0.1 part by mass or more, and more preferably 0.5 part by mass or more with respect to 100 parts by mass of the adhesive contained in the adhesive layer. The content of the adhesion aid is preferably 40 parts by mass or less, and more preferably 35 parts by mass or less, with respect to 100 parts by mass of the adhesive contained in the adhesive layer.
When the adhesion aid is an isocyanate compound, the content of the isocyanate compound is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, based on 100 parts by mass of the adhesive contained in the adhesive layer. It is preferably 18 parts by mass or more, and more preferably 18 parts by mass or more. The content of the isocyanate compound is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and 30 parts by mass or less with respect to 100 parts by mass of the adhesive contained in the adhesive layer. Is even more preferable.
When the adhesion aid is an organosilicon compound, the content of the organosilicon compound is preferably 0.1 part by mass or more, preferably 0.5 part by mass, based on 100 parts by mass of the adhesive contained in the adhesive layer. The above is more preferable. The content of the organic silicon compound is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, with respect to 100 parts by mass of the adhesive contained in the adhesive layer.

When the adhesion aid is an isocyanate compound, the content of the isocyanate group contained in the adhesive layer is preferably 0.5 mmol / g or more, more preferably 0.6 mmol / g or more, and 0. It is more preferably 8 mmol / g or more, and particularly preferably 0.9 mmol / g or more. The content of the isocyanate group contained in the adhesive layer is preferably 3.0 mmol / g or less, more preferably 2.5 mmol / g or less, and preferably 2.0 mmol / g or less. It is more preferably 1.5 mmol / g or less, and particularly preferably 1.5 mmol / g or less.

The adhesive layer can be formed, for example, by applying a composition for forming an adhesive layer to a fine fibrous cellulose-containing sheet. When applying the composition for forming an adhesive layer, a roll coater, a bar coater, a gravure coater, a die coater, a curtain coater, an air doctor coater, or the like can be used. Since such an adhesive layer is a layer that covers the surface of the fine fibrous cellulose-containing sheet, it may be called a surface treatment layer.

<Inorganic layer>
The laminate may further have an inorganic layer. The inorganic layer may be provided on the outermost layer of the laminated body, or may be provided as a layer constituting the inside 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)
The laminate of the present embodiment is transparent, has excellent mechanical strength and dimensional stability, and can exhibit excellent durability even under high humidity conditions. Therefore, the laminate of the present embodiment is preferable for optical members and substrates in various display devices, substrates for electronic devices, members for home appliances, window materials for various vehicles and buildings, interior materials, exterior materials, solar cell members, and the like. Used.

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.

<Manufacturing example 1>
(Manufacturing of phosphorylated pulp)
As raw material pulp, softwood kraft pulp made by Oji Paper (solid content 93% by mass, basis weight 208 g / m ² sheets, disintegrated and measured according to JIS P 811-2: 2012 Canadian standard drainage degree (CSF) ) Used 700 mL). The raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. To obtain a chemical-impregnated pulp. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 200 seconds to introduce a phosphoric acid group into the cellulose in the pulp to obtain a phosphorylated pulp.

Then, the obtained phosphorylated pulp was washed. The washing treatment is carried out by repeating the operation of pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp, stirring the pulp dispersion liquid so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. went. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

Next, the phosphorylated pulp after washing was subjected to alkali treatment (neutralization treatment) as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N aqueous sodium hydroxide solution was added little by little with stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. .. Next, the phosphorylated pulp slurry was dehydrated to obtain phosphorylated pulp subjected to alkali treatment (neutralization treatment).

Next, the phosphorylated pulp after the neutralization treatment was subjected to the above-mentioned washing treatment. The infrared absorption spectrum of the phosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption ^{of the phosphate group based on P = O was observed around 1230 cm -1} , and it was confirmed that the phosphate group was added to the pulp. Further, when the obtained phosphorylated pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

(Defibration treatment)
Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion (A) containing fine fibrous cellulose.

By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. Moreover, when the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 3 to 5 nm. The amount of phosphoric acid group (first dissociated acid amount) measured by the measuring method described later was 1.45 mmol / g. The total amount of dissociated acid was 2.45 mmol / g.

(Measurement of phosphate group amount)
The amount of phosphate groups in the fine fibrous cellulose (equal to the amount of phosphate groups in the phosphorylated pulp) is adjusted by adding ion exchange water to the fine fibrous cellulose dispersion containing the target fine fibrous cellulose. It was adjusted to 0.2% by mass, treated with an ion exchange resin, and then titrated with an alkali to measure the weight.
The treatment with the ion exchange resin was carried out by adding a strongly acidic ion exchange resin (Amberjet 1024; Organo Co., Ltd., conditioned) having a volume of 1/10 to the fine fibrous cellulose-containing slurry and shaking for 1 hour. After that, it was poured on a mesh having a mesh size of 90 μm to separate the resin and the slurry.
In addition, titration using alkali changes the pH value indicated by the slurry while adding 10 μL of 0.1 N sodium hydroxide aqueous solution to the fine fibrous cellulose-containing slurry after treatment with an ion exchange resin every 5 seconds. It was done by measuring. The titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of the titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 10). The amount of alkali required from the start of the titration to the first end point is equal to the amount of the first dissociated acid in the slurry used for the titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. The amount of alkali (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated is the amount of phosphate groups (first dissociated acid amount) (mmol / g). ). Further, the value obtained by dividing the amount of alkali (mmol) required from the start of titration to the second end point by the solid content (g) in the slurry to be titrated was defined as the total amount of dissociated acid (mmol / g).

<Manufacturing example 2>
(Production of TEMPO oxide pulp)
As the raw material pulp, softwood kraft pulp (undried) manufactured by Oji Paper Co., Ltd. was used. This raw material pulp was subjected to alkaline TEMPO oxidation treatment as follows. First, the raw material pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), and 10 parts by mass of sodium bromide are added to 10000 parts by mass of water. It was dispersed in the parts. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so as to be 3.8 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and when no change was observed in the pH, the reaction was considered to be completed.

Next, the obtained TEMPO oxide pulp was washed. The washing treatment is carried out by dehydrating the pulp slurry after TEMPO oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring and uniformly dispersing the pulp slurry, and then repeating the operation of filtration and dehydration. It was. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

With respect to the TEMPO oxidized pulp thus obtained, the amount of carboxy groups measured by the measuring method described later was 1.30 mmol / g. Further, when the obtained TEMPO oxide pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, confirming that it had cellulose type I crystals.

(Defibration treatment)
Ion-exchanged water was added to the obtained TEMPO oxidized pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion (B) containing fine fibrous cellulose. By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. Moreover, when the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 3 to 5 nm. The amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.

(Measurement of carboxy group amount)
The carboxy group amount of the fine fibrous cellulose (equal to the carboxy group amount of the TEMPO oxide pulp) is set to 0 by adding ion-exchanged water to the fine fibrous cellulose dispersion containing the target fine fibrous cellulose. It was measured at 2% by mass, treated with an ion exchange resin, and then titrated with an alkali.
The treatment with an ion exchange resin is carried out by adding a 1/10 volume of a strongly acidic ion exchange resin (Amberjet 1024; manufactured by Organo Corporation, conditioned) to a slurry containing 0.2% by mass of fine fibrous cellulose for 1 hour. After the shaking treatment, the resin and the slurry were separated by pouring onto a mesh having a mesh size of 90 μm.
In addition, the titration using alkali was performed by measuring the change in the pH value indicated by the slurry while adding a 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after the treatment with the ion exchange resin. .. By observing the change in pH while adding an aqueous sodium hydroxide solution, a titration curve as shown in FIG. 11 can be obtained. As shown in FIG. 11, in this neutralization titration, there is one point in which the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Observed. The maximum point of this increment is called the first end point. Here, the region from the start of titration to the first end point in FIG. 11 is referred to as a first region. The amount of alkali required in the first region is equal to the amount of carboxy groups in the slurry used for titration. Then, the amount of alkali (mmol) required in the first region of the titration curve is divided by the solid content (g) in the fine fibrous cellulose-containing slurry to be titrated, so that the amount of carboxy group introduced (mmol / g). ) Was calculated.
The above-mentioned amount of carboxy group introduced (mmol / g) is the amount of substituents per 1 g of the mass of fibrous cellulose when the ^{pair ion of the carboxy group is hydrogen ion (H +) (hereinafter, the amount of carboxy group (acid).} Type)) is shown.

<Manufacturing example 3>
(Manufacturing of subphosphorylated pulp)
The same procedure as in Production Example 1 was carried out except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate to obtain phosphorous oxide pulp.

The infrared absorption spectrum of the obtained subphosphorylated pulp was measured using FT-IR. As a result, absorption based on P = O of the phosphonic acid group, which is a tautomer of the phosphite group, was observed around ^{1210 cm -1, and the phosphonic acid group (phosphonic acid group) was added to the pulp.} Was confirmed. Further, when the obtained subphosphorylated pulp was tested and analyzed by an X-ray diffractometer, two positions were found: 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed in, and it was confirmed that it had cellulose type I crystals.

(Defibration treatment)
Ion-exchanged water was added to the obtained subphosphorized pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated four times at a pressure of 200 MPa with a wet atomizing device (manufactured by Sugino Machine Limited, Starburst) to obtain a fine fibrous cellulose dispersion (C) containing fine fibrous cellulose. By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. Moreover, when the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 3 to 5 nm. The amount of phosphorous acid group (first dissociated acid amount) measured by the measuring method described later was 1.51 mmol / g. The total amount of dissociated acid was 1.54 mmol / g.

(Measurement of phosphite group amount)
The amount of phosphite group in fine fibrous cellulose (equal to the amount of phosphite group in phosphite pulp) is obtained by adding ion exchange water to the fine fibrous cellulose dispersion containing the target fine fibrous cellulose. The content was set to 0.2% by mass, treated with an ion exchange resin, and then titrated with an alkali to measure the content.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) having a volume of 1/10 was added to the fine fibrous cellulose-containing slurry, and the mixture was shaken for 1 hour. After that, it was poured on a mesh having a mesh size of 90 μm to separate the resin and the slurry.
In addition, titration using alkali changes the pH value indicated by the slurry while adding 10 μL of 0.1 N sodium hydroxide aqueous solution to the fine fibrous cellulose-containing slurry after treatment with an ion exchange resin every 5 seconds. It was done by measuring. The titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of the titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkali dropped) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 10). The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of alkali required from the start of the titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for the titration. The amount of alkali (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated is the amount of phosphite group (first dissociated acid amount) (mmol / g). Further, the value obtained by dividing the amount of alkali (mmol) required from the start of titration to the second end point by the solid content (g) in the slurry to be titrated was defined as the total amount of dissociated acid (mmol / g).

<Example 1>
(Sheet of fine fibrous cellulose)
Using the fine fibrous cellulose dispersion liquid (A), a fine fibrous cellulose-containing sheet having ^{a finished basis weight of 200 g / m 2 was obtained by the method described in Table 2014/196357.}

(Manufacturing of laminate)
A flat plate mold for injection molding (size of gap portion at the time of mold clamping; length 280 mm, width) that forms a gap portion by combining a concave mold and a convex mold with an injection molding tester (NISSEI PLASTIC INDUSTRY CO., LTD., NEX140). 80 mm, thickness 4 mm) was set. Further, the fine fibrous cellulose-containing sheet was cut into a length of 170 mm and a width of 75 mm. Next, the fine fibrous cellulose-containing sheet after cutting was fixed in the mold by a clamp mechanism installed at the end of the central surface of the gap portion formed by the two molds in the thickness direction. At this time, the center lines in the length direction and the width direction of the mold plane and the length direction and the width direction of the fine fibrous cellulose-containing sheet are overlapped, and the mold plane and the fine fibrous cellulose-containing sheet are parallel to each other. Arranged as. After fixing the fine fibrous cellulose-containing sheet, the mold is closed, and the molten polycarbonate resin (Iupilon S-3000 manufactured by Mitsubishi Engineering Plastics Co., Ltd.) is gold under the conditions of the mold temperature of 110 ° C. and the resin temperature of 290 ° C. It was injected into the mold (at this time, polycarbonate resin was injected on both sides of the fine fibrous cellulose-containing sheet). Further, the mold temperature was lowered to 60 ° C. to solidify the polycarbonate resin. By the above procedure, a laminate in which a fine fibrous cellulose-containing sheet (CNF sheet) was encapsulated in a resin component was obtained.

FIG. 2A is a schematic view for explaining the configuration of the laminated body obtained in Example 1. Further, FIG. 3A is a cross-sectional view of the laminated body obtained in Example 1, and shows a layer structure in a cross section parallel to the length direction (the direction L in FIG. 2A). FIG. 3B is a cross-sectional view of the laminated body obtained in Example 1, and shows a layer structure in a cross section parallel to the width direction (direction W in FIG. 2A). The cross section is a surface that passes through the center point of the laminated body, and is a surface that appears when cut in the thickness direction.

<Example 2>
In the production of the laminate of Example 1, when the fine fibrous cellulose-containing sheet is fixed in the mold, the length direction and the width direction of the mold plane and the length direction and the width direction of the fine fibrous cellulose-containing sheet Example except that the center lines of the above are overlapped and the fine fibrous cellulose-containing sheet is arranged at a position 500 μm inward in the thickness direction from the concave mold plane (void forming surface) at the time of mold clamping. In the same manner as in No. 1, a laminate in which the fine fibrous cellulose-containing sheet was encapsulated in the resin component was obtained.
FIG. 4A is a cross-sectional view of the laminated body obtained in Example 2 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 4B is a cross-sectional view of the laminated body obtained in Example 2 and shows a layer structure in a cross section parallel to the width direction.

<Example 3>
(Manufacturing of laminate)
A flat plate mold for injection molding (size of the gap at the time of mold clamping; length 280 mm, width) that forms a gap by combining a concave mold and a convex mold in an injection molding tester (NEX140, manufactured by Nissei Jushi Kogyo Co., Ltd.). 80 mm, thickness 4 mm) was set. Further, the fine fibrous cellulose-containing sheet obtained in Example 1 was cut into a length of 170 mm and a width of 75 mm. Next, the fine fibrous cellulose-containing sheet after cutting was cut into a polycarbonate resin sheet (manufactured by Teijin Ltd., Panlite PC-2151, thickness 200 μm) having a length of 180 mm and a width of 80 mm so that the center points of the sheets coincide with each other. Overlaid on. Then, this laminated sheet was fixed on a concave mold plane (air gap forming surface) with a heat-resistant tape. At this time, the length of the polycarbonate resin sheet is set so that the polycarbonate resin sheet is in contact with one of the concave mold planes (void forming surface), and the length of the polycarbonate resin sheet is located 50 mm inward from the longitudinal end side of the concave mold plane. Arranged so that the directional edges match. After that, the mold was closed, and a molten polycarbonate resin (Iupilon S-3000 manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was injected into the mold under the conditions of a mold temperature of 110 ° C. and a resin temperature of 290 ° C. (at this time, Polycarbonate resin was injected onto one surface of the fine fibrous cellulose-containing sheet). Further, the mold temperature was lowered to 60 ° C. to solidify the polycarbonate resin. By the above procedure, a laminate in which the fine fibrous cellulose-containing sheet was encapsulated in the resin component was obtained.
FIG. 5A is a cross-sectional view of the laminated body obtained in Example 3 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 5B is a cross-sectional view of the laminated body obtained in Example 3 and shows a layer structure in a cross section parallel to the width direction.

<Example 4>
(Sheet of fine fibrous cellulose)
In the sheet formation of the fine fibrous cellulose of Example 1, the finished basis weight of the sheet was set to 100 g / m ² . Other procedures were carried out in the same manner to obtain a fine fibrous cellulose-containing sheet. In the same manner, another fine fibrous cellulose-containing sheet having a basis weight of 100 g / m ^{2 was prepared.}

(Lamination of surface treatment layer)
In the same procedure as the lamination of the surface treatment layer of Example 1, two fine fibrous cellulose-containing sheets in which the surface treatment layers were laminated on both sides of the fine fibrous cellulose-containing sheet were obtained.

(Manufacturing of laminate)
A flat plate mold for injection molding (size of gap portion at the time of mold clamping; length 280 mm, width) that forms a gap portion by combining a concave mold and a convex mold with an injection molding tester (NISSEI PLASTIC INDUSTRY CO., LTD., NEX140). 80 mm, thickness 4 mm) was set. Further, two sheets containing fine fibrous cellulose were cut into a length of 170 mm and a width of 75 mm. Next, the fine fibrous cellulose-containing sheet after each cut was cut into two sheets of polycarbonate resin (manufactured by Teijin Corporation, Panlite PC-2151, thickness 200 μm) having a length of 180 mm and a width of 80 mm. They were overlaid so that they would match. Then, these two laminated sheets were fixed on a set of mold planes (void forming surfaces) with heat-resistant tape. At this time, the sheet of the polycarbonate resin should be in contact with each mold plane (void forming surface), at a position 50 mm from the longitudinal end side of the concave mold plane, and the convex mold plane (convex portion). The sheets of the polycarbonate resin were arranged so that the longitudinal edges of the polycarbonate resin sheets coincided with each other at a position 50 mm from the longitudinal edge of the upper plane). After that, the mold was closed, and a molten polycarbonate resin (Iupilon S-3000 manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was injected into the mold under the conditions of a mold temperature of 110 ° C. and a resin temperature of 290 ° C. (at this time, Polycarbonate resin was injected between the sheets containing fine fibrous cellulose). Further, the mold temperature was lowered to 60 ° C. to solidify the polycarbonate resin. By the above procedure, a laminate in which the fine fibrous cellulose-containing sheet was encapsulated in the resin component was obtained.
FIG. 7A is a cross-sectional view of the laminated body obtained in Example 4, showing a layer structure in a cross section parallel to the length direction. Further, FIG. 7B is a cross-sectional view of the laminated body obtained in Example 4, showing the layer structure in the cross section parallel to the width direction.

<Example 5>
In the production of the laminate of Example 4, instead of the polycarbonate resin, a molten polycarbonate / acrylic alloy resin (Iupilon MB6001UR manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was injected into the mold. Other procedures were the same as in Example 4 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 7A is a cross-sectional view of the laminated body obtained in Example 5, showing a layer structure in a cross section parallel to the length direction. Further, FIG. 7B is a cross-sectional view of the laminated body obtained in Example 5, showing a layer structure in a cross section parallel to the width direction.

<Example 6>
In the sheet formation of the fine fibrous cellulose of Example 4, the finished basis weight of the sheet was set to 200 g / m ² . Other procedures were the same as in Example 4 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 12A is a cross-sectional view of the laminated body obtained in Example 6 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 12B is a cross-sectional view of the laminated body obtained in Example 6 and shows a layer structure in a cross section parallel to the width direction.

<Example 7>
In the production of the laminate of Example 6, instead of the polycarbonate resin, a molten polycarbonate / acrylic alloy resin (Iupilon MB6001UR manufactured by Mitsubishi Engineering Plastics Co., Ltd.) was injected into the mold. Other procedures were the same as in Example 6 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 12A is a cross-sectional view of the laminated body obtained in Example 7, and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 12B is a cross-sectional view of the laminated body obtained in Example 7, showing a layer structure in a cross section parallel to the width direction.

<Example 8>
In the production of the laminate of Example 7, a polycarbonate / acrylic alloy resin sheet (manufactured by Mitsubishi Gas Chemical Company, Ltd., thickness 200 μm) was used instead of the polycarbonate resin sheet. Other procedures were the same as in Example 7 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 12A is a cross-sectional view of the laminated body obtained in Example 8 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 12B is a cross-sectional view of the laminated body obtained in Example 8 and shows a layer structure in a cross section parallel to the width direction.

<Example 9>
In the sheeting of the fine fibrous cellulose of Example 8, the fine fibrous cellulose dispersion (B) was used instead of the fine fibrous cellulose dispersion (A). Other procedures were the same as in Example 8 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 12A is a cross-sectional view of the laminated body obtained in Example 9, and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 12B is a cross-sectional view of the laminated body obtained in Example 9, showing a layer structure in a cross section parallel to the width direction.

<Example 10>
In the sheeting of the fine fibrous cellulose of Example 8, the fine fibrous cellulose dispersion (C) was used instead of the fine fibrous cellulose dispersion (A). Other procedures were the same as in Example 8 to obtain a laminate in which the fine fibrous cellulose-containing sheet was encapsulated in the resin component.
FIG. 12A is a cross-sectional view of the laminated body obtained in Example 10 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 12B is a cross-sectional view of the laminated body obtained in Example 10 and shows a layer structure in a cross section parallel to the width direction.

<Example 11>
In the production of the laminate of Example 8, two fine fibrous cellulose-containing sheets were cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 8 to obtain a laminate. In this laminated body, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
Next, in the above laminate, a polyamide resin (manufactured by Hakko Co., Ltd., hot melt) melted by a hot melt applicator (manufactured by Hakko Co., Ltd., HAKKO MELTER 804) in a portion where the edge of the fine fibrous cellulose-containing sheet is exposed. Adhesive No. 810) was applied. At this time, the coating thickness of the polyamide resin was set to 2 mm. By the above procedure, a laminate in which the fine fibrous cellulose-containing sheet was encapsulated in the resin component was obtained.
FIG. 9A is a cross-sectional view of the laminated body obtained in Example 11 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 9B is a cross-sectional view of the laminated body obtained in Example 11 and shows a layer structure in a cross section parallel to the width direction.

<Example 12>
In the production of the laminate of Example 1, in addition to the fine fibrous cellulose-containing sheet, a polycarbonate resin sheet (manufactured by Teijin Co., Ltd., Panlite PC-2151, thickness 200 μm) is used as a concave mold plane (air gap forming surface). , And the convex mold plane (air gap forming surface) were fixed with heat-resistant tape, respectively. At this time, 50 mm from the longitudinal end of the concave mold plane and 50 mm from the longitudinal end of the convex mold plane (convex upper plane), respectively, in the longitudinal direction of the polycarbonate resin sheet. Arranged so that the edges match. Other procedures were the same as in Example 1 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 8A is a cross-sectional view of the laminated body obtained in Example 12, showing a layer structure in a cross section parallel to the length direction. Further, FIG. 8B is a cross-sectional view of the laminated body obtained in Example 12, showing a layer structure in a cross section parallel to the width direction.

<Example 13>
In the production of the laminate of Example 2, another fine fibrous cellulose-containing sheet was arranged so as to face each other in the thickness direction in the mold. When fixing this fine fibrous cellulose-containing sheet in the mold, the center lines in the length direction and the width direction of the concave mold plane and the length direction and the width direction of the fine fibrous cellulose-containing sheet are superimposed. At the time of mold clamping, the fine fibrous cellulose-containing sheet was arranged at a position 500 μm inward in the thickness direction from each mold plane (air gap forming surface). Other procedures were the same as in Example 2 to obtain a laminate in which a fine fibrous cellulose-containing sheet was encapsulated in a resin component.
FIG. 6A is a cross-sectional view of the laminated body obtained in Example 13 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 6B is a cross-sectional view of the laminated body obtained in Example 13 and shows a layer structure in a cross section parallel to the width direction.

<Comparative example 1>
In the production of the laminate of Example 1, the fine fibrous cellulose-containing sheet was not placed in the mold. Other procedures were the same as in Example 1 to obtain a molded product made of only polycarbonate resin.
FIG. 13A is a cross-sectional view of the laminated body obtained in Comparative Example 1 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 13B is a cross-sectional view of the laminated body obtained in Comparative Example 1 and shows a layer structure in a cross section parallel to the width direction.

<Comparative example 2>
In the production of the laminate of Example 1, the fine fibrous cellulose-containing sheet was cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 1 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 14A is a cross-sectional view of the laminated body obtained in Comparative Example 2 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 14B is a cross-sectional view of the laminated body obtained in Comparative Example 2 and shows a layer structure in a cross section parallel to the width direction.

<Comparative example 3>
In the production of the laminate of Example 2, the fine fibrous cellulose-containing sheet was cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 2 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 15A is a cross-sectional view of the laminated body obtained in Comparative Example 3 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 15B is a cross-sectional view of the laminated body obtained in Comparative Example 3 and shows a layer structure in a cross section parallel to the width direction.

<Comparative example 4>
In the production of the laminate of Example 3, the fine fibrous cellulose-containing sheet was cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 3 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 16A is a cross-sectional view of the laminated body obtained in Comparative Example 4, showing a layer structure in a cross section parallel to the length direction. Further, FIG. 16B is a cross-sectional view of the laminated body obtained in Comparative Example 4, showing a layer structure in a cross section parallel to the width direction.

<Comparative example 5>
In the production of the laminate of Example 4, two fine fibrous cellulose-containing sheets were cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 4 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 17A is a cross-sectional view of the laminated body obtained in Comparative Example 5, showing a layer structure in a cross section parallel to the length direction. Further, FIG. 17B is a cross-sectional view of the laminated body obtained in Comparative Example 5, showing a layer structure in a cross section parallel to the width direction.

<Comparative Example 6>
In the production of the laminate of Example 5, two fine fibrous cellulose-containing sheets were cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 5 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 17A is a cross-sectional view of the laminated body obtained in Comparative Example 6 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 17B is a cross-sectional view of the laminated body obtained in Comparative Example 6 and shows a layer structure in a cross section parallel to the width direction.

<Comparative Example 7>
In the production of the laminate of Example 6, two fine fibrous cellulose-containing sheets were cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 6 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 18A is a cross-sectional view of the laminated body obtained in Comparative Example 7, and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 18B is a cross-sectional view of the laminated body obtained in Comparative Example 7, showing a layer structure in a cross section parallel to the width direction.

<Comparative Example 8>
In the production of the laminate of Example 7, two fine fibrous cellulose-containing sheets were cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 7 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 18A is a cross-sectional view of the laminated body obtained in Comparative Example 8 and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 18B is a cross-sectional view of the laminated body obtained in Comparative Example 8 and shows a layer structure in a cross section parallel to the width direction.

<Comparative Example 9>
In the production of the laminate of Example 8, two fine fibrous cellulose-containing sheets were cut into a length of 170 mm and a width of 80 mm. Other procedures were the same as in Example 8 to obtain a laminate. In this laminate, the edge of the fine fibrous cellulose-containing sheet was exposed without being covered with the resin component.
FIG. 18A is a cross-sectional view of the laminated body obtained in Comparative Example 9, and shows a layer structure in a cross section parallel to the length direction. Further, FIG. 18B is a cross-sectional view of the laminated body obtained in Comparative Example 9, showing a layer structure in a cross section parallel to the width direction.

<Evaluation>
(Flexural modulus)
A test piece having a length of 80 mm and a width of 10 mm was cut out from the laminated body and the molded body (Comparative Example 1). The laminated body was cut out from the portion where the fine fibrous cellulose-containing sheet was present. Using this test piece, a bending test was performed using a universal material testing machine (Tencilon RTC-1250A, manufactured by A & D Co., Ltd.) under the conditions of a distance between fulcrums of 64 mm and a deflection speed of 2 mm / min in accordance with JIS K 7171: 2016. The test temperature was 23 ° C. The bending elasticity (GPa) was calculated from the slope of the stress / strain curve in which the strain was between 0.0005 and 0.0025.

(Coefficient of linear thermal expansion)
A test piece having a length of 50 mm and a width of 10 mm was cut out from the laminated body and the molded body (Comparative Example 1). The laminated body was cut out from the portion where the fine fibrous cellulose-containing sheet was present. Using this test piece, using a thermomechanical analyzer (TMA / SS6100 manufactured by Seiko Instruments), the amount of change in the length of the test piece under the conditions of a temperature range of 23 to 90 ° C and a heating rate of 5 ° C / min. Was measured, and the linear thermal expansion coefficient (ppm / K) was calculated by dividing the amount of change in length in the temperature range of 30 to 80 ° C. by the amount of change in temperature.

(Yellowness)
A 50 mm square test piece was cut out from the laminated body and the molded body (Comparative Example 1). The laminated body was cut out from the portion where the fine fibrous cellulose-containing sheet was present. Using this test piece, the yellowness was measured using a color meter (Color Cutei, manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS K 7373: 2006.

(warp)
The laminate and the molded product (Comparative Example 1) were allowed to stand for 24 hours in an environment with a temperature of 23 ° C. and a relative humidity of 50%. Then, the laminated body and the molded body were observed, and the degree of warpage was evaluated according to the following criteria.
A: No curvature is observed in the laminated body (molded body), and the flat plate shape is maintained.
B: The laminated body (molded body) has a slight curvature, but the flat plate shape is generally maintained.
C: The laminated body (molded body) is significantly curved and does not maintain the flat plate shape.

(durability)
The laminate and the molded product (Comparative Example 1) were immersed in warm water having a temperature of 60 ° C. for 24 hours. Then, the laminated body and the molded body were observed, and the durability quality was evaluated according to the following criteria.
A: No change in appearance was observed in the laminated body (molded body), and the laminated structure and flat plate shape were maintained.
B: Laminated body (molded body) Although slight changes in appearance are observed, the laminated structure and flat plate shape are generally maintained.
C: A remarkable change in appearance was observed in the laminated body (molded body), and the laminated structure and the flat plate shape were not maintained.

As is clear from Table 1, in the laminate obtained in the examples, the flexural modulus was improved, the linear thermal expansion coefficient was reduced, and the durability was further excellent.
In particular, in Example 2 in which the fine fibrous cellulose-containing sheet was arranged in the region near the surface layer, the effect of improving the bending elasticity was greater than in Example 1. In Example 2, a slight deterioration in durability quality was observed, but in Example 3 in which the resin sheet was placed on the outermost layer of the laminate and the fine fibrous cellulose-containing sheet was laminated on the resin sheet, the durability quality was higher. Was good. Further, in Examples 2 and 3, a slight warp was observed in the laminated body, but in Example 4 in which the fine fibrous cellulose-containing sheet was arranged in the region near the surface layer of both planes, the warp was suppressed and bending was performed. The effect of improving the elastic modulus became even greater.
On the other hand, in Comparative Examples 2 to 9, in which the edge of the fine fibrous cellulose-containing sheet was exposed from the resin material in the laminated body, the durability quality was significantly deteriorated.

In Examples 5, 7, and 8 in which the polycarbonate / acrylic alloy resin was used as the resin material, more excellent flexural modulus and linear thermal expansion coefficient were exhibited.
Further, in Examples 8 and 10 in which phosphorylation or subphosphorylation was adopted as the method for modifying the fine fibrous cellulose, the yellowness of the laminate was suppressed to be lower than in Example 9 in which TEMPO oxidation was adopted. Was there.

<Evaluation>
(Flexural modulus at high temperature)
For the laminate obtained in Example 8, the flexural modulus at a higher temperature was measured by the following procedure. A test piece having a length of 80 mm and a width of 10 mm was cut out from the portion of the laminate in which the fine fibrous cellulose-containing sheet was present. A universal material tester (A & D Co., Ltd., Tencilon RTC-) that uses this test piece and conforms to JIS K 7171: 2016 except that the test temperature is set to 80 ° C. under the conditions of a distance between fulcrums of 64 mm and a deflection speed of 2 mm / min. A bending test was performed according to 1250A). The flexural modulus (GPa) was calculated from the slope of the stress / strain curve in which the strain was between 0.0005 and 0.0025. The calculated bending elasticity was 4.3 GPa, and it was confirmed that the bending elasticity was maintained even at a high temperature.

(Durability at high temperature)
Further, with respect to the laminate obtained in Example 8, the durability under higher temperature was evaluated by the following procedure. After allowing the laminate to stand in a constant temperature bath at a temperature of 110 ° C. for 720 hours in an air atmosphere, the appearance of the laminate was observed. It was confirmed that the appearance of the laminate did not change significantly, the interlayer adhesion was maintained, and the durability at high temperatures was good.

10 Fine fibrous cellulose-containing sheet 20 Resin sheet 30 Resin layer 30a Molten resin 35 Coating resin 50 Mold 51 Injection port 52 Fixing member 100 Laminated body 101 Molded body

Claims (8)

A step of injecting a molten resin into a mold in which a sheet containing fibrous cellulose having a fiber width of 1000 nm or less is arranged.
A method for producing a laminate including the step of solidifying the molten resin.
A method for producing a laminate, wherein the sheet containing the fibrous cellulose is wrapped with a resin component in the laminate. The method for producing a laminate according to claim 1, wherein in the laminate, the fibrous cellulose is unevenly distributed in an unexposed region in a region near the surface layer in the thickness direction of the laminate. In the step of injecting the molten resin, the sheets containing the fibrous cellulose are arranged so as to face each other along both sides of the inner wall of the mold.
The method for producing a laminate according to claim 1 or 2, wherein at least a part of the molten resin is filled between the opposing sheets containing the fibrous cellulose. The method for producing a laminate according to any one of claims 1 to 3, wherein in the step of injecting the molten resin, the sheet containing the fibrous cellulose is fixed to the inner wall of the mold via the resin sheet. The method for producing a laminate according to any one of claims 1 to 4, wherein the area of the maximum surface of the laminate is larger than the area of the maximum surface of the sheet containing the fibrous cellulose. The method for producing a laminate according to any one of claims 1 to 5, wherein in the laminate, the edge of the sheet containing the fibrous cellulose is covered with a resin component derived from the molten resin. .. The method for producing a laminate according to any one of claims 1 to 6, further comprising a step of coating an exposed portion of the sheet containing the fibrous cellulose after the step of solidifying the molten resin. The method for producing a laminate according to any one of claims 1 to 7, wherein the molten resin contains an alloy resin containing a polycarbonate resin and an acrylic resin.

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