JP2022115099A - Multi-layered resin glass and vehicle window unit - Google Patents

Abstract

To provide a multi-layered resin glass having excellent soundproof performance.SOLUTION: The present invention relates to a multi-layered resin glass which is a multi-layered resin glass having at least two resin moldings and a hollow layer therebetween, the resin moldings containing fibrous cellulose having a fiber width of less than or equal to 1000 nm, the resin moldings containing an amorphous resin, and relates to a vehicle window unit having the multi-layered resin glass.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a double-layer resin glass excellent in soundproof performance and an automobile window unit having the double-layer resin glass.

BACKGROUND ART In recent years, with the aim of reducing the weight of automobiles, the use of resin glass for various window glasses in automobiles has been studied. In addition to rigidity and dimensional stability, soundproofing performance to prevent external noise from entering is one of the important physical properties when using resin glass for window glass.

By the way, in recent years, attention has been paid to materials using reproducible natural fibers due to an alternative to petroleum resources and an increase in environmental awareness. Among natural fibers, the use of fine fibrous cellulose having a fiber diameter of 1 μm or less obtained from wood-derived fibrous cellulose (pulp) has attracted attention. Sheets composed of fine fibrous cellulose and composite sheets containing fine fibrous cellulose-containing sheets and resins are being developed. It is known that the strength and the like are greatly improved.

For example, Patent Literature 1 discloses a laminate including a polycarbonate resin layer and a cellulose fiber layer.

Japanese Patent No. 4985573

The use of resin glass for automobile window glass can achieve weight reduction, but has the problem of inferior soundproof performance compared to inorganic glass.

As a result of intensive studies to solve the above problems, the present inventors have found a resin molded article containing fine fibrous cellulose in resin glass, which has at least one hollow layer between the molded articles. It has been found that by having a multilayer structure, a multilayer resin glass having excellent soundproof performance can be obtained.

(1) A multilayer resin glass having at least two resin molded bodies and a hollow layer between them, wherein the resin molded bodies contain fibrous cellulose with a fiber width of 1000 nm or less,
The resin molding is multilayer resin glass containing an amorphous resin.
(2) A multi-layer resin glass having at least two resin molded bodies and a hollow layer between them, wherein the resin molded bodies comprise a fiber layer containing fibrous cellulose with a fiber width of 1000 nm or less, an adhesive layer and a resin layer. has a laminated structure in this order,
The resin layer is a multilayer resin glass containing an amorphous resin.
(3) The double-layered resin glass according to (1) or (2), wherein the amorphous resin is polycarbonate.
(4) The double-layered resin glass according to any one of (1) to (3), wherein the thickness of at least one of the resin moldings is 200 μm or more.
(5) The double-layer resin glass according to any one of (1) to (4), wherein the resin molding has a total light transmittance of 80% or more.
(6) The multi-layered resin glass according to any one of (1) to (5), wherein the resin molding has a haze of 5% or less.
(7) The double-layer resin glass according to any one of (1) to (6), wherein the resin molding has a flexural modulus of 2.4 GPa or more.
(8) The double-layer resin glass according to any one of (1) to (7), wherein the resin molding has a coefficient of linear thermal expansion of 70 ppm/K or less.
(9) An automobile window unit comprising the double-layer resin glass according to any one of (1) to (8).

ADVANTAGE OF THE INVENTION According to this invention, the multilayer resin glass which has the outstanding soundproof performance can be provided.

FIG. 1 is a cross-sectional view for explaining an example of the configuration of the double-layered resin glass. FIG. 2 is a cross-sectional view illustrating an example of the configuration of the double-layered resin glass. FIG. 3 is a cross-sectional view illustrating an example of the configuration of a resin molded body. FIG. 4 is a cross-sectional view illustrating an example of the configuration of a resin molded body. FIG. 5 is a cross-sectional view illustrating an example of the configuration of a resin molded body. FIG. 6 is a cross-sectional view illustrating an example of the configuration of a resin molded body. FIG. 7 is a graph showing the relationship between the amount of dropped NaOH and the pH for a fibrous cellulose-containing slurry having a phosphorous acid group. FIG. 8 is a graph showing the relationship between the dropping amount of NaOH and the pH for a fibrous cellulose-containing slurry having carboxyl groups. FIG. 9 is a cross-sectional view illustrating an example of the configuration of a resin molded body. FIG. 10 is a cross-sectional view illustrating an example of the configuration of a resin molded body.

The present invention will be described in detail below. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments.

(multilayer resin glass)
A first aspect of the present invention is a multilayer resin glass having at least two resin molded bodies and a hollow layer therebetween, wherein the resin molded body comprises fibrous cellulose having a fiber width of 1000 nm or less and an amorphous resin. It relates to a multi-layered resin glass containing. The present invention also relates to a window structure using the multi-layered resin glass. In this specification, resin glass refers to a material containing resin that can be substituted for glass material, and hollow layer refers to a space provided between resin moldings. That is, the present invention provides a multi-layered resin glass having at least two resin molded bodies, wherein a space is formed between the resin molded bodies in the multi-layered resin glass, and the resin molded bodies are composed of fibers. The present invention relates to a multi-layered resin glass containing fibrous cellulose with a width of 1000 nm or less and an amorphous resin.

A second aspect of the present invention is a multi-layer resin glass having at least two resin molded bodies and a hollow layer therebetween, wherein the resin molded bodies contain fibers having a fiber width of 1000 nm or less and containing fibrous cellulose. It has a laminated structure having a layer, an adhesive layer and a resin layer in this order, and the resin layer relates to a multilayer resin glass containing an amorphous resin. The present invention also relates to a window structure using the multi-layered resin glass. As described above, in this specification, the hollow layer means a space provided between resin moldings. That is, the present invention provides a multi-layered resin glass having at least two resin molded bodies, wherein a space is formed between the resin molded bodies in the multi-layered resin glass, and the resin molded bodies are composed of fibers. It has a laminated structure having a fiber layer containing fibrous cellulose with a width of 1000 nm or less, an adhesive layer and a resin layer in this order, and the resin layer relates to a multilayer resin glass containing an amorphous resin.

The multi-layered resin glass 200 of the present invention, for example, as shown in FIG. and the resin moldings (100-A, 100-B) by applying the primary sealing material 60 to adhere the resin moldings (100-A, 100-B) and the spacers 50, and then the spacers 50. It is obtained by applying the secondary sealing material 70 to the portion surrounded by the outer periphery and the two resin moldings (100-A, 100-B) to integrate all the members. For example, in FIG. 1, the area surrounded by the spacer 50 and the resin moldings (100-A, 100-B) serves as a space.

In general, when the flexural rigidity of a material increases, the soundproofing performance (transmission loss) in the low frequency range tends to increase. In the present invention, by using fine fibrous cellulose in the resin molding constituting the double-layer resin glass, the bending elastic modulus of the resin molding can be increased, and as a result, the bending rigidity of the resin molding can be increased. Therefore, it is considered that the soundproofing performance especially in the low frequency range can be improved more effectively.

Since the double-layered resin glass of the present invention is used, for example, for automobile windows (automotive windows), the total thickness of the resin molding and the hollow layer is preferably 10 mm or less, more preferably 8 mm or less. . The thicknesses of the resin molding and the hollow layer can be arbitrarily changed as long as the total thickness is within the above range. Similarly, at least two resin molding layers and at least one hollow layer are sufficient, and the number of layers can be changed arbitrarily according to desired physical properties and shape.

FIG. 2 shows an example of the structure of the multi-layer resin glass 200 according to the present invention. It is a multi-layered resin glass 200 having layers. In such a configuration, the intermediate layer 80 can be a resin molding or a fibrous layer containing fine fibrous cellulose. In the multi-layered resin glass 200 having such a structure, the spacers 50 are arranged between the resin molding 100-A and the intermediate layer 80 and between the intermediate layer 80 and the resin molding 100-B. 50 and the resin molded body (100-A, 100-B) or the intermediate layer 80 is coated with the primary sealing material 60 to seal the resin molded body (100-A, 100-B) or the intermediate layer 80 and the spacer 50. After bonding, the secondary sealing material 70 is applied to the portion surrounded by the outer periphery of the spacer 50 and the resin molded bodies (100-A, 100-B) or the intermediate layer 80 to integrate all the members. obtained by

When a fibrous layer containing fine fibrous cellulose is used as the intermediate layer, the fibrous layer may be used alone, or an adhesive layer may be provided on at least one surface of the fibrous layer. In this case, the thickness of the fiber layer as the intermediate layer is preferably 10 µm or more, more preferably 20 µm or more, still more preferably 30 µm or more, and particularly preferably 50 µm or more. Although the upper limit of the thickness of the fiber layer is not particularly limited, it is preferably 500 μm or less, more preferably 400 μm or less, still more preferably 300 μm or less, and particularly preferably 200 μm or less.

When a resin molded body is used for the intermediate layer 80, the laminated structure and thickness of the resin molded body (100-A, 100-B) and the intermediate layer 80 may be the same or different. In order to prevent the uniformity of the resin glass as a whole and the warp of the members, the intermediate layer 80 is preferably a resin molded body, and the laminated structure and thickness of the resin molded bodies are preferably the same.

(hollow layer)
The hollow layer is a space surrounded by a resin molding, a spacer, a primary sealing material, and a secondary sealing material. The thickness of the hollow layer (the width of the space) is preferably 200 µm or more, more preferably 500 µm or more, and even more preferably 800 µm or more. The thickness of the hollow layer (the width of the space) is preferably 10000 µm or less, more preferably 6000 µm or less, and even more preferably 5000 µm or less.

It is preferable that gas exists in the hollow layer, and the gas filled in the hollow layer is preferably air or He or Ne that is lighter than air.

(spacer)
The spacer is provided between the resin molded bodies, and arranged along the periphery of the resin molded body. The spacer preferably has a desiccant inside, and the spacer is usually fixed to the resin molding via a primary sealing material. That is, the multi-layered resin glass of the present invention is a multi-layered resin glass having at least two resin molded bodies and a spacer therebetween, and is a space (hollow layer) surrounded by the resin molded body and the spacer. It relates to a multi-layered resin glass having

Aluminum, resin, resin composite material, composite material of aluminum and resin, or the like is used for the spacer. Examples of resins that can be used include butyl rubber, vinyl chloride-based resins (which may contain phthalic acid compounds and phosphoric acid compounds as plasticizers, and metal organic acid compounds as stabilizers), styrene and acrylonitrile. A resin containing a copolymer as a main component (which may be filled with glass fiber or the like) may be mentioned. When the spacer is made of resin, it is preferable to use a resin containing a desiccant and formed into a spacer shape.

The thickness of the spacer is preferably 200 μm or more, more preferably 500 μm or more, and even more preferably 800 μm or more. Also, the thickness of the spacer is preferably 10000 μm or less, more preferably 6000 μm or less, and even more preferably 5000 μm or less. By setting the thickness of the spacer within the above range, a hollow layer (space space) having a preferable thickness can be formed between the resin moldings.

(Primary sealing material, secondary sealing material)
The primary sealing material is an adhesive that bonds the resin molded body and the spacer and seals the hollow layer. Further, the secondary sealing material is an adhesive provided on the exposed side end surface (the end surface facing the intermediate layer side end surface) of the spacer in the double-layered resin glass, and seals the gap between the resin moldings. is. A polyisobutylene-based resin or the like can be used as the primary sealing material, and a polysulfide-based resin, a silicone-based resin, or the like can be used as the secondary sealing material.

(resin molding)
The resin molding in the present invention contains fibrous cellulose with a fiber width of 1000 nm or less. Here, the resin molding may have a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, or may have a single layer structure in which a resin and fibrous cellulose are mixed. The resin molding contains an amorphous resin. When the resin molding has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the amorphous resin is preferably contained in the resin layer. Moreover, when the resin molding has the laminated structure, the adhesive layer preferably contains a polymer, and the polymer preferably has a glass transition temperature of less than 170°C.
In this specification, fibrous cellulose having a fiber width of 1000 nm or less is sometimes referred to as fine fibrous cellulose or CNF.

Since the resin molded body constituting the double-layered resin glass of the present invention has the above structure, the resin molded body has both a high elastic modulus (bending elastic modulus) and a low coefficient of linear thermal expansion. Therefore, the multilayer resin glass of the present invention also has both a high elastic modulus (bending elastic modulus) and a low coefficient of linear thermal expansion.

The bending elastic modulus of the resin molding is preferably 2.3 GPa or more, more preferably 2.4 GPa or more, still more preferably 2.5 GPa or more, and even more preferably 3.0 GPa or more. It is preferably 3.5 GPa or more, more preferably 4.0 GPa or more, and particularly preferably 4.0 GPa or more. Although the upper limit of the bending elastic modulus of the resin molding is not particularly limited, it may be, for example, 50.0 GPa or less. Here, the flexural modulus of the resin molding is a value measured in accordance with JIS K 7171:2016 under the conditions of a distance between fulcrums of 64 mm and a deflection rate of 2 mm/min. 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 bending elastic modulus is calculated from the slope of the stress-strain curve when the strain is between 0.0005 and 0.0025. A universal material testing machine, such as Tensilon RTC-1250A manufactured by A&D Co., Ltd., can be used as a flexural modulus measuring instrument.

The linear thermal expansion coefficient of the resin molding is preferably 70 ppm/K or less, more preferably 65 ppm/K or less, further preferably 60 ppm/K or less, and 55 ppm/K or less. More preferably, it is particularly preferably 50 ppm/K or less. Although the lower limit of the coefficient of linear thermal expansion of the resin molding is not particularly limited, it may be 5 ppm/K or more, for example. Here, the coefficient of linear thermal expansion of the resin molded body is obtained by measuring the amount of change in the length of a test piece having a length of 50 mm and a width of 10 mm under the conditions of a temperature range of 23 to 90 ° C. and a temperature increase rate of 5 ° C./min. This value is calculated by dividing the amount of change in length between 30 and 80° C. by the amount of change in temperature. A thermomechanical analyzer can be used to measure the amount of change in length, for example, TMA/SS6100 manufactured by Seiko Instruments Inc. can be used.

The resin molding is also excellent in transparency, and its yellowness is kept low. Specifically, the haze of the resin molding is preferably 5% or less, more preferably 3% or less, even more preferably 2% or less, and 1.5% or less. Especially preferred. The resin molding may have a haze of 0%. In addition, the yellowness (YI value) of the resin molding is preferably 40 or less, more preferably 30 or less, even more preferably 20 or less, even more preferably 15 or less, and 10 The following are particularly preferred. Incidentally, the yellowness index (YI value) of the resin molding may be zero. The haze of the resin molding is a value measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in accordance with JIS K 7136:2000. The yellowness index (YI value) of the resin molding is a value measured using a color meter (manufactured by Suga Test Instruments Co., Ltd., Color Cute i) in accordance with JIS K 7373:2006.

Further, the total light transmittance of the resin molding is preferably 80% or more, more preferably 85% or more. The upper limit of the total light transmittance of the resin molding is not particularly limited, and may be 100%, for example. Here, the total light transmittance of the resin molding is a value measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory) in accordance with, for example, JIS K 7361-1:1997.

The resin molding contains fine fibrous cellulose, which will be described in detail in the item (fiber layer) described later, and an amorphous resin, which will be described in detail in the item (resin layer) described later. Examples of amorphous resins include polycarbonate, polyvinyl chloride, polystyrene, polymethylmethacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyetherimide, and polyamideimide. Among them, the amorphous resin is preferably a polycarbonate, more preferably a polycarbonate obtained by homopolymerization. Also, the amorphous 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 resin molding tends to increase and the coefficient of linear thermal expansion tends to decrease. Examples of polycarbonates include aromatic polycarbonate resins and aliphatic polycarbonate resins. These specific polycarbonate resins are known, and examples thereof include polycarbonate resins described in JP-A-2010-023275.

In this embodiment, the resin molding may have a single-layer structure in which resin and fine fibrous cellulose are mixed. When the resin molding has a single layer structure in which resin and fine fibrous cellulose are mixed, it is preferable that the fine fibrous cellulose is uniformly dispersed in the resin molding. The state in which fine fibrous cellulose is uniformly dispersed means that the content of fibrous cellulose at arbitrary 10 locations in the resin molding is within the range of the average value ±10% by mass.

The resin molding may contain optional components. Examples of optional components include known components used in the field of resin films, such as fillers, pigments, dyes, and ultraviolet absorbers.

FIG. 3 is a cross-sectional view illustrating an embodiment in which the resin molding has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order. As shown in FIG. 3, the resin molding 100 has a fiber layer 10, an adhesive layer 20 and a resin layer 30 in this order. Here, the fiber layer 10, the adhesive layer 20 and the resin layer 30 are laminated in this order, and each layer is laminated so as to be in direct contact with each other. That is, the adhesive layer 20 is provided between the fiber layer 10 and the resin layer 30 and is provided in direct contact with both the fiber layer 10 and the resin layer 30 .

The resin molding may further have an adhesive layer and a resin layer on the other surface of the fiber layer. Specifically, the resin molded article of the present invention may be a resin molded article having a resin layer, an adhesive layer, a fiber layer, an adhesive layer and a resin layer in this order. In this case, the plurality of resin layers may be resin layers of the same kind, or may be resin layers of different kinds. Further, the plurality of adhesive layers may be of the same kind or may be different kinds of adhesive layers.

FIG. 4 is a cross-sectional view for explaining the configuration of the resin molding described above. In the resin molding 100 of FIG. 4, the resin layer 30, the adhesive layer 20, the fiber layer 10, the adhesive layer 20 and the resin layer 30 are laminated in this order. That is, adhesive layers 20 are provided on both surfaces of the fiber layer 10, and resin layers 30 are laminated on the respective adhesive layers 20 to form a five-layer structure. As described above, the resin molding 100 preferably has a configuration in which the adhesive layer 20 and the resin layer 30 are laminated on both sides of the fiber layer 10 .

FIG. 5 is a cross-sectional view illustrating another embodiment of the resin molding. In the resin molding 100 of FIG. 5, the fiber layer 10 is wrapped with the resin component. Here, the state in which the fiber layer 10 is covered with the resin component means a state in which no portion of the fiber layer 10 is exposed to the surface and the periphery is covered with the resin component. At least part of the resin component encapsulating the fiber layer 10 is preferably an amorphous resin forming the resin layer 30 . In the resin molding 100, the fiber layer 10 is preferably wrapped with an amorphous resin or an adhesive layer. In this case, as shown in FIG. 5, the entire surface of the fiber layer 10 may be covered with an amorphous resin or an adhesive layer. Also, the fiber layer 10 may be partially covered with another resin member. Such a resin member may be a cover material preliminarily laminated on the fiber layer 10, and examples of the cover material include a resin film. Note that such a cover material may cover the exposed portion of the fiber layer 10 after the resin molding 100 is formed.

In FIG. 5, the resin layer 30 exists so as to surround the fiber layer 10 and constitutes a series of resin regions. It has a layer configuration of layer 20 /fiber layer 10 /adhesive layer 20 /resin layer 30 . Therefore, in this specification, the layer structure of the resin molding 100 in FIG.

As shown in FIGS. 4 and 5 , in the resin molded body 100 , the fiber layer 10 may exist in the central region in the thickness direction of the resin molded body 100 . That is, in the resin molded body, the fibrous cellulose may be unevenly distributed in the central region in the thickness direction of the resin molded body. In such a resin molded article, the occurrence of warping can be suppressed, and the water resistance of the resin molded article can be enhanced.

Moreover, as shown in FIG. 6, the fiber layer 10 may exist in the surface layer vicinity area|region of the thickness direction of the resin molding 100. Moreover, as shown in FIG. That is, in the resin molded body, the fibrous cellulose may be unevenly distributed in the surface layer vicinity region in the thickness direction of the resin molded body. Note that the near-surface region in the thickness direction of the resin molded body is a region existing from the surface of the resin molded body to 30% of the total thickness of the resin molded body, and the region excluding the exposed outermost surface. say. By unevenly distributing the fibrous cellulose in the non-exposed region, which is the surface layer vicinity region in the thickness direction of the resin molded body, the bending elastic modulus of the resin molded body can be increased more effectively. Furthermore, as shown in FIG. 6, the fiber layer 10 may exist in two or more layers in the resin molding 100 . For example, two fiber layers 10 may be present in the near-surface regions on the front side and the back side, respectively. In this way, by allowing the fine fibrous cellulose to exist evenly on one side and the other side of the resin molded body, variations in the strength of the resin molded body can be suppressed, and warpage occurs in the resin molded body. can be suppressed.

As shown in FIG. 6, when the fiber layer 10 exists in the surface layer vicinity region in the thickness direction of the resin molded body 100, the outermost resin layer 30 may be a layer formed of a resin film. good. That is, the outermost resin layer 30 may be a layer formed by laminating a resin film on the adhesive layer 20 provided on the fiber layer 10 . After laminating the resin film on the adhesive layer 20, a heat press process may be provided as necessary. Thus, by forming the outermost resin layer 30 from a resin film, the durability and impact resistance of the resin molding can be more effectively improved.

Moreover, the resin molding may have optional layers as described later. In addition, in the resin molding, each layer may be provided with only one layer, or may be provided with two or more layers.

The thickness of one resin molded body is preferably 200 μm or more, more preferably 500 μm or more, still more preferably 1.0 mm or more, further preferably 2.0 mm or more. Moreover, the upper limit of the thickness of one sheet of the resin molding is not particularly limited, and may be, for example, 10 mm or less.

In addition, it is preferable that the resin molding is a hot press molding. Specifically, when forming the resin layer in the resin molding, the resin layer is preferably molded by hot press molding. By using a hot press molded article, it becomes easier to obtain a resin molded article having excellent interlayer adhesion. In addition, a high elastic modulus (flexural modulus) and a low coefficient of linear thermal expansion can be easily achieved in the resin molded body, and the resin molded body can also have excellent design and durability. In addition, it is also possible to reduce the cost of equipment introduction by molding the resin molded body by hot press molding.

(fiber layer)
When the resin molding has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the layer (fiber layer) containing fine fibrous cellulose is fibrous cellulose having a fiber width of 1000 nm or less (fine fibrous cellulose). including. The fiber width of fibrous cellulose is preferably 100 nm or less, more preferably 50 nm or less, even more preferably 10 nm or less, and particularly preferably 8 nm or less. As a result, the transparency of the fiber layer is increased, and the strength of the resin molded body is increased when the resin molded body is formed.

The fiber width of fibrous cellulose can be measured, for example, by electron microscopic observation. The number average fiber width of fibrous cellulose is 1000 nm or less. The number average fiber width of fibrous cellulose is preferably 1 nm or more and 1000 nm or less, more preferably 1 nm or more and 100 nm or less, further preferably 1 nm or more and 50 nm or less, and 1 nm or more and 10 nm or less. Especially preferred. By setting the number-average fiber width of the fibrous cellulose within the above range, the transparency of the fiber layer is enhanced, and the strength of the resin molding is enhanced when the resin molding is formed. The fibrous cellulose is, for example, single fibrous cellulose.

The number 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 serve as a sample for TEM observation. do. SEM images of surfaces cast on glass may be observed if they contain wide fibers. Then, an electron microscope image is observed at a magnification of 1,000, 5,000, 10,000, or 50,000 times depending on the width of the fiber to be observed. However, the sample, observation conditions and magnification are adjusted so as to satisfy the following conditions.
(1) A single straight line X is drawn at an arbitrary point in the observed image, and 20 or more fibers intersect the straight line X.
(2) Draw a straight line Y that intersects the straight line perpendicularly in the same image, and 20 or more fibers intersect the straight line Y.
Widths of fibers intersecting the straight lines X and Y are visually read from the observation image satisfying the above conditions. In this way, at least three sets of observed images of surface portions that do not overlap each other are obtained. Then, for each image, the width of the fiber that crosses straight line X and straight line Y is read. This gives at least 20 x 2 x 3 = 120 fiber width readings. And let the average value of the read fiber width be the number average fiber width of fibrous cellulose.

Although the fiber length of the fibrous cellulose is not particularly limited, it 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 crystalline regions of the fibrous cellulose can be suppressed. Moreover, it becomes possible to make the slurry viscosity of fibrous cellulose into an appropriate range. The fiber length of fibrous cellulose can be determined by image analysis using, for example, TEM, SEM, and AFM.

Preferably, the fibrous cellulose has a Type I crystal structure. Here, the fact that the fibrous cellulose has a type I crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ=1.5418 Å) monochromated with graphite. Specifically, it can be identified by having typical peaks at two positions near 2θ=14° or more and 17° or less and 2θ=22° or more and 23° or less. The proportion of the I-type crystal structure in the fine fibrous cellulose is, for example, preferably 30% or more, more preferably 40% or more, even more 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 degree of crystallinity is determined by a conventional method from the pattern of X-ray diffraction profiles (Seagal et al., Textile Research Journal, vol. 29, p. 786, 1959).

Although the axial ratio (fiber length/fiber width) of fibrous cellulose is not particularly limited, it is preferably 20 or more and 10,000 or less, and more preferably 50 or more and 1,000 or less. A sheet containing fine fibrous cellulose can be easily formed by making the axial ratio equal to or higher than the above lower limit. In addition, a sufficient thickening property can be easily obtained when a solvent dispersion is produced. By setting the axial ratio to the above upper limit or less, handling such as dilution becomes easier, for example, when fibrous cellulose is treated as an aqueous dispersion, which is preferable.

Fibrous cellulose, for example, has both crystalline and amorphous regions. In particular, fine fibrous cellulose having both a crystalline region and an amorphous 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 ionic substituents and nonionic substituents. An ionic substituent may be introduced into the fibrous cellulose in order to improve the dispersibility of the fibrous cellulose in the dispersion medium and increase the fibrillation efficiency in the fibrillation treatment. The ionic substituents can include, for example, either one or both of an anionic group and a cationic group. The ionic substituent is preferably a group introduced into the fibrous cellulose via an ester bond or an ether bond, more preferably a group introduced into the fibrous cellulose via an ester bond. In this case, the ester bond is preferably formed by dehydration condensation between the hydroxyl group of the fibrous cellulose and the compound serving as the ionic substituent. Nonionic substituents can also include, for example, alkyl groups and acyl groups. When introducing a substituent into fibrous cellulose, it is preferable to introduce an anionic group as an ionic substituent. On the other hand, the fibrous cellulose may not have an ionic substituent introduced therein. As described later, an ionic substituent is introduced into the fibrous cellulose, and after fibrillation treatment, the ionic substitution is performed. A step of removing the group may be provided.

The anionic group as the ionic group includes, for example, a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group), a carboxy group or a substituent derived from a carboxy group (simply referred to as a carboxy group). a sulfur oxoacid group or a substituent derived from a sulfur oxoacid group (sometimes simply referred to as a sulfur oxoacid group), a xanthate group or a substituent derived from a xanthate group (sometimes simply referred to as a xanthate group) , a phosphonic group or a substituent derived from a phosphonic group (sometimes simply referred to as a phosphonic group), a phosphine group or a substituent derived from a phosphine group (sometimes simply referred to as a phosphine group), a sulfone group or a substituent derived from a sulfone group group (sometimes simply referred to as sulfone group), carboxyalkyl group (including carboxymethyl group and carboxyethyl group), and the like. Among them, the anionic group is selected from the group consisting of a phosphate group, a substituent derived from a phosphate group, a carboxy group, a sulfur oxo acid group, a substituent derived from a sulfur oxo acid group, a carboxymethyl group, and a sulfone group. at least one selected from the group consisting of a phosphate group, a substituent derived from a phosphate group, a carboxy group, a sulfur oxo acid group, and a substituent derived from a sulfur oxo acid group is more preferred, and a phosphorous acid group is particularly preferred. By introducing a phosphorus oxoacid group as an anionic group, the dispersibility of fibrous cellulose can be further improved, for example, even under alkaline or acidic conditions, and as a result, a sheet with high strength and high transparency can be obtained. easier.
Cationic groups as ionic groups include, for example, an ammonium group, a phosphonium group, and a sulfonium group. Among them, the cationic group is preferably an ammonium group.

A phosphorous acid group or a substituent derived from a phosphorous acid group is, for example, a substituent represented by the following formula (1). A plurality of substituents represented by the following formula (1) may be introduced into each fibrous cellulose. In this case, the plural introduced substituents represented by the following formula (1) may be the same or different.

In formula (1), a, b and n are natural numbers, and m is an arbitrary number (where a=b×m). At least one of n α and α' is O 2 ^- , and the rest are R or OR. Note that all of α and α' may be O 2 ⁻ . All of the n αs may be the same or different. β ^b+ is a monovalent or higher cation composed of an organic substance or an inorganic substance.

Each R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated linear hydrocarbon group, an unsaturated-branched hydrocarbon group A hydrogen group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or a derivative group thereof. Also, in formula (1), n is preferably 1.

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

In addition, the derivative group in R is selected from functional groups such as carboxy group, carboxylate group (—COO ⁻ ), hydroxy group, amino group and ammonium group for the main chain or side chain of the above various hydrocarbon groups. functional groups to which at least one type is added or substituted, but are not particularly limited. Although the number of carbon atoms constituting the main chain of R is not particularly limited, it is preferably 20 or less, more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R within the above range, the molecular weight of the phosphorous acid group can be set within an appropriate range, facilitating penetration into the fiber raw material and increasing the yield of fine cellulose fibers. can also In addition, when a plurality of R are present in the formula (1) or when a plurality of types of substituents represented by the above formula (1) are introduced into the fibrous cellulose, the plurality of Rs present are the same. There may be or may be different.

β ^b+ is a monovalent or higher cation composed of an organic substance or an inorganic substance. An organic onium ion can be mentioned as a cation having a valence of 1 or more composed of an organic substance. Organic onium ions include, for example, organic ammonium ions and organic phosphonium ions. Examples of organic ammonium ions include aliphatic ammonium ions and aromatic ammonium ions, and examples of organic phosphonium ions include aliphatic phosphonium ions and aromatic phosphonium ions. Examples of monovalent or higher-valent cations composed of inorganic substances include ions of alkali metals such as sodium, potassium, or lithium, ions of divalent metals such as calcium or magnesium, hydrogen ions, and ammonium ions. In addition, when a plurality of β ^b+ are present in the formula (1) or when a plurality of types of substituents represented by the above formula (1) are introduced into the fibrous cellulose, the plurality of β ^b+ are each They may be the same or different. As the cation having a valence of 1 or more composed of an organic substance or an inorganic substance, sodium or potassium ions are preferable, but are not particularly limited, because they do not easily turn yellow when fiber raw materials containing β ^b+ are heated and are easily industrially available. .

More specifically, the phosphoric acid group or the substituent derived from the phosphoric acid group includes a phosphoric acid group (—PO ₃ H ₂ ), a salt of a phosphoric acid group, a phosphorous acid group (phosphonic acid group) (—PO ₂ H ₂ ), salts of phosphite group (phosphonic acid group). In addition, the phosphoric acid group or the substituent derived from the phosphoric acid group includes a condensed phosphoric acid group (e.g., pyrophosphate group), a condensed phosphonic acid group (e.g., polyphosphonic acid group), a phosphoric acid ester group ( For example, it may be a monomethyl phosphate group, a polyoxyethylene alkyl phosphate group), an alkylphosphonic acid group (eg, a methylphosphonic acid group), or the like.

Further, the sulfur oxoacid group (a sulfur oxoacid group or a substituent derived from a sulfur oxoacid group) is, for example, a substituent represented by the following formula (2). A plurality of substituents represented by the following formula (2) may be introduced into each fibrous cellulose. In this case, the plural introduced substituents represented by the following formula (2) may be the same or different.

In the above structural formula, b and n are natural numbers, p is 0 or 1, and m is an arbitrary number (where 1=b×m). In addition, when n is 2 or more, multiple p may be the same number or may be different numbers. In the above structural formula, β ^b+ is a monovalent or higher cation composed of an organic substance or an inorganic substance. An organic onium ion can be mentioned as a cation having a valence of 1 or more composed of an organic substance. Organic onium ions include, for example, organic ammonium ions and organic phosphonium ions. Examples of organic ammonium ions include aliphatic ammonium ions and aromatic ammonium ions, and examples of organic phosphonium ions include aliphatic phosphonium ions and aromatic phosphonium ions. Examples of monovalent or higher-valent cations composed of inorganic substances include ions of alkali metals such as sodium, potassium, or lithium, ions of divalent metals such as calcium or magnesium, hydrogen ions, and ammonium ions. When multiple types of substituents represented by the above formula (2) are introduced into fibrous cellulose, the multiple β ^b+ may be the same or different. As the cation having a valence of 1 or more composed of an organic substance or an inorganic substance, sodium or potassium ions are preferable, but are not particularly limited, because they do not easily turn yellow when fiber raw materials containing β ^b+ are heated and are easily industrially available. .

The amount of the ionic substituent introduced into fibrous cellulose may be 0.00 mmol/g per 1 g (mass) of fibrous cellulose, but is preferably 0.05 mmol/g or more. In addition, the amount of the ionic substituent introduced into fibrous cellulose is preferably 5.20 mmol/g or less, more preferably 3.65 mmol/g or less per 1 g (mass) of fibrous cellulose. It is more preferably 50 mmol/g or less, particularly preferably 3.00 mmol/g or less. By setting the amount of the ionic substituent to be introduced within the above range, the fiber raw material can be easily made finer, and the stability of the fibrous cellulose can be enhanced. Also, by setting the amount of the ionic substituent to be introduced within the above range, good properties can be exhibited in various applications such as a thickening agent for fibrous cellulose. Here, the denominator in units of mmol/g indicates the mass of fibrous cellulose when the counter ion of the ionic substituent is hydrogen ion (H ⁺ ).

In addition, the amount of the ionic substituent introduced into fibrous cellulose may be less than 0.50 mmol/g, may be 0.40 mmol/g or less, or may be 0.30 mmol per 1 g (mass) of fibrous cellulose. /g or less, 0.25 mmol/g or less, or 0.15 mmol/g or less. The fibrous cellulose in which the introduction amount of the ionic substituent is within the above range may be obtained, for example, by removing the ionic substituent introduced into the fibrous cellulose. By forming a fibrous layer or a resin molding using such fibrous cellulose, it becomes easier to obtain a resin molding having a lower haze and a lower degree of yellowness.

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

FIG. 7 is a graph showing the relationship between the amount of dropped NaOH and the pH for a fibrous cellulose-containing slurry having a phosphorous acid group. The amount of phosphorus oxoacid groups introduced into fibrous cellulose is measured, for example, as follows.
First, a slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. In addition, before the treatment with the strongly acidic ion exchange resin, a defibration treatment similar to the fibrillation treatment step described below may be performed on the object to be measured, if necessary.
Next, the change in pH is observed while adding sodium hydroxide aqueous solution, and a titration curve as shown in the upper part of FIG. 7 is obtained. The titration curve shown in the upper part of FIG. 7 plots the measured pH against the amount of alkali added, and the titration curve shown in the lower part of FIG. 7 plots the pH against the amount of alkali added. The increment (differential value) (1/mmol) is plotted. In this neutralization titration, two points where the increment (the differential value of the pH with respect to the amount of alkali dropped) are maximized are confirmed in the curve obtained by plotting the measured pH against the amount of alkali added. Among these, the maximum point of the increment obtained first when the alkali is first 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 first dissociated acid amount of 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 second dissociated acid amount of fibrous cellulose contained in the slurry used for titration, and the amount of alkali required from the start of titration to the second end point is equal to the amount of fibrous cellulose contained in the slurry used for titration. equal to the total dissociated acid content of A value obtained by dividing the amount of alkali required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated is the amount of phosphorus oxoacid group introduced (mmol/g). In addition, when simply referring to the amount of phosphorus oxoacid groups introduced (or the amount of phosphorus oxoacid groups), it means the amount of the first dissociated acid.
In FIG. 7, the region from the start of titration to the first end point is called the first region, and the region from the first end point to the second end point is called the second region. For example, when the phosphoric acid group is a phosphoric acid group, and the phosphoric acid group causes condensation, it appears that the amount of weakly acidic groups in the phosphoric acid group (also referred to herein as the second dissociated acid amount) is The amount of alkali required in the second region is less than that required in the first region. On the other hand, the amount of strongly acidic groups in the phosphorus oxoacid group (also referred to herein as the amount of first dissociated acid) matches the amount of phosphorus atoms regardless of the presence or absence of condensation. In addition, when the phosphorous acid group is a phosphorous acid group, the weakly acidic group does not exist in the phosphorous acid group, so the amount of alkali required for the second region is reduced, or the amount of alkali required for the second region is may be zero. In this case, the titration curve has one point at which the pH increment is maximum.

In addition, since the denominator of the amount of introduced phosphate groups (mmol/g) indicates the mass of the acid-form fibrous cellulose, the amount of phosphate groups possessed by the acid-form fibrous cellulose (hereinafter referred to as the phosphate group amount (acid form)). On the other hand, when the counter ion of the phosphooxy acid group is substituted 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 the counter ion. Thus, the amount of phosphate groups (hereinafter referred to as the amount of phosphate groups (type C)) possessed by fibrous cellulose whose counter ion is cation C can be determined.
That is, it is calculated by the following formula.
Phosphorus oxo acid group amount (C type) = Phosphorus oxo acid group amount (acid type) / {1 + (W-1) × A / 1000}
A [mmol/g]: Total amount of anions derived from phosphate groups possessed by fibrous cellulose (total dissociated acid amount of phosphate groups)
W: Formula weight per valence of cation C (for example, 23 for Na and 9 for Al)

When measuring the amount of phosphate groups by titration, if the amount of 1 drop of aqueous sodium hydroxide solution is too large, or if the titration interval is too short, the amount of phosphate groups will be lower than it should be, and accurate values cannot be obtained. sometimes not. As a suitable drop amount and titration interval, for example, it is desirable to titrate 10 to 50 μL of 0.1N sodium hydroxide aqueous solution every 5 to 30 seconds. 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. 8 is a graph showing the relationship between the dropping amount of NaOH and pH for slurry containing fibrous cellulose having carboxyl groups. The amount of carboxyl groups introduced into fibrous cellulose is measured, for example, as follows.
First, a slurry containing fibrous cellulose is treated with a strongly acidic ion exchange resin. In addition, before the treatment with the strongly acidic ion exchange resin, a defibration treatment similar to the fibrillation treatment step described below may be performed on the object to be measured, if necessary.
Next, the change in pH is observed while adding sodium hydroxide aqueous solution, and a titration curve as shown in the upper part of FIG. 8 is obtained. The titration curve shown in the upper part of FIG. 8 plots the measured pH against the amount of alkali added, and the titration curve shown in the lower part of FIG. 8 plots the pH against the amount of alkali added. The increment (differential value) (1/mmol) is plotted. In this neutralization titration, in the curve plotting the measured pH against the amount of alkali added, one point where the increment (the differential value of pH with respect to the amount of alkali dropped) is maximum was confirmed. 1 end point. Here, the region from the start of titration to the first end point in FIG. 8 is called the first region. The amount of alkali required in the first region is equal to the amount of carboxyl groups in the slurry used for titration. Then, by dividing the alkali amount (mmol) required in the first region of the titration curve by the solid content (g) in the slurry containing the fibrous cellulose to be titrated, the introduction amount of the carboxy group (mmol/ g) is calculated.
The amount of carboxyl groups introduced (mmol/g) described above is the amount of substituents per 1 g of mass of fibrous cellulose (hereinafter referred to as the amount of carboxyl groups ( ^acid type)).

In addition, since the denominator of the amount of introduced carboxy groups (mmol/g) is the mass of the acid-type fibrous cellulose, the amount of carboxy groups possessed by the acid-type fibrous cellulose (hereinafter referred to as the amount of carboxy groups (acid-type )). On the other hand, when the counterion of the carboxy group is substituted 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 the counterion. , the amount of carboxy groups (hereinafter referred to as the amount of carboxy groups (C type)) possessed by fibrous cellulose whose counter ion is cation C can be obtained.
That is, it is calculated by the following formula.
Carboxy group amount (C type) = carboxy group amount (acid form) / {1 + (W-1) x (carboxy group amount (acid form)) / 1000}
W: Formula weight per valence of cation C (for example, 23 for Na and 9 for Al)

When measuring the amount of ionic groups by the titration method, if the amount of 1 drop of aqueous sodium hydroxide solution is too large, or if the titration interval is too short, the amount of ionic groups will be lower than it should be, and accurate values cannot be obtained. sometimes not. As a suitable drop amount and titration interval, for example, it is desirable to titrate 10 to 50 μL of 0.1N sodium hydroxide aqueous solution every 5 to 30 seconds. 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.

The amount of sulfur oxoacid group or sulfone group introduced into fibrous cellulose is determined by wet ashing fibrous cellulose with perchloric acid and concentrated nitric acid, diluting it at an appropriate ratio, and measuring the amount of sulfur by ICP emission spectrometry. can be calculated by The value obtained by dividing the amount of sulfur by the absolute dry mass of the fibrous cellulose tested is the amount of sulfur oxoacid groups or the amount of sulfone groups (unit: mmol/g).
is.

The introduction amount of the xanthate group into the fibrous cellulose can be measured by the Bredee method as follows. First, 40 mL of a saturated ammonium chloride solution was added to 1.5 parts by mass (absolute dry mass) of fibrous cellulose, mixed well while crushing the sample with a glass rod, and left for about 15 minutes. 25) and wash thoroughly with saturated ammonium chloride solution. Next, the sample is placed in a 500 mL tall beaker together with the GFP filter paper, 50 mL of 0.5 M sodium hydroxide solution (5° C.) is added, stirred, and allowed to stand for 15 minutes. After adding the phenolphthalein solution until the solution turns pink, 1.5 M acetic acid is added and the point at which the solution turns from pink to colorless is taken as the neutralization point. After neutralization, 250 mL of distilled water is added and well stirred, and 10 mL of 1.5 M acetic acid and 10 mL of 0.05 mol/L iodine solution are added using a whole pipette. Then, this solution is titrated with a 0.05 mol/L sodium thiosulfate solution, and the amount of xanthate groups is calculated from the following equation from the titration amount of sodium thiosulfate and the absolute dry mass of fibrous cellulose.
Xanthate group amount (mmol/g) = (0.05 x 10 x 2-0.05 x sodium thiosulfate titer (mL))/1000/absolute dry mass of fibrous cellulose (g)

The content of fibrous cellulose is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 30% by mass or more, based on the total mass of the fiber layer. It is more preferably at least 70% by mass, particularly preferably at least 70% by mass. Also, the content of fibrous cellulose may be 100% by mass with respect to the total mass of the fibrous layer. That is, the fiber layer may be a layer made of fibrous cellulose.

The thickness of one fiber layer is preferably 20 μm or more, more preferably 40 μm or more, and even more preferably 60 μm or more. The thickness of one fiber layer is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 250 μm or less. In addition, even when two or more fiber layers are provided in the resin molding, the thickness of each layer is preferably within the above range. By setting the thickness of the fiber layer within the above range, strength for reinforcing the resin molding can be easily obtained. Moreover, the production efficiency of the fiber layer can be improved. Here, the thickness of one fiber layer is a value measured by cutting out a cross section of the resin molding with a band saw, slide saw or laser processing machine and observing the cross section with an optical microscope or an electron microscope.

The density of the fiber layer is preferably 0.5 g/cm ³ or more, more preferably 1.0 g/cm ³ or more, even more preferably 1.2 g/cm ³ or more, and 1.4 g/cm 3 or more. /cm ³ or more is particularly preferred. Also, the upper limit of the density of the fiber layer is not particularly limited, and may be, for example, 3.0 g/cm ³ . By setting the density of the fiber layer within the above range, strength for reinforcing the resin molding can be easily obtained. Note that the density of the fiber layer is a value calculated according to JIS P 8118:2014 from the basis weight and thickness of the layer.

The basis weight of one fiber layer is preferably 10 g/m ² or more, more preferably 30 g/m ² or more, still more preferably 50 g/m ² or more, and 100 g/m ² or more. is particularly preferred. The basis weight of one fiber layer is preferably 1500 g/m ² or less, more preferably 750 g/m ² or less, and even more preferably 500 g/m ² or less. When a plurality of fiber layers are provided, the total basis weight of the fiber layers is preferably 50 g/m ² or more, more preferably 100 g/m ² or more. Also, the total basis weight of the fiber 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 fiber layer may be 150 g/m ² or more, or may be 200 g/m ² or more. Also, the total basis weight of the fiber layers may be 300 g/m ² or more, or may be 400 g/m ² or more. By increasing the basis weight of the fiber layer, the flexural modulus of the resin molded body can be increased more effectively, and the linear thermal expansion coefficient of the resin molded body can be further decreased. Here, the basis weight of the fiber layer is a value calculated according to the following method, for example, by cutting with an ultramicrotome UC-7 (manufactured by JEOL) so that only the fiber layer remains. The weight of the fiber layer cut into a size of 2 cm square or more is measured, and the weight is divided by the area of the cut fiber layer to calculate the basis weight of the fiber layer.

The haze of the fiber layer is preferably 2% or less, more preferably 1.5% or less, even more preferably 1% or less. On the other hand, the lower limit of the haze of the fiber layer is not particularly limited, and may be 0%, for example. Here, the haze of the fiber layer is measured with, for example, an ultramicrotome UC-7 (manufactured by JEOL) so that only the fiber layer remains, and is measured according to JIS K 7136 with a haze meter (manufactured by Murakami Color Research Laboratory, HM -150).

The total light transmittance of the fiber layer is preferably 85% or higher, more preferably 90% or higher, even more preferably 91% or higher. On the other hand, the upper limit of the total light transmittance of the fiber layer is not particularly limited, and may be 100%, for example. Here, the total light transmittance of the fiber layer is measured using, for example, an ultramicrotome UC-7 (manufactured by JEOL), so that only the fiber layer remains, is measured according to JIS K 7361, and a haze meter (Murakami Color Research Laboratory Co., Ltd. manufactured by HM-150).

The fiber layer may contain optional components in addition to the fine fibrous cellulose. Optional components include hydrophilic macromolecules, hydrophilic low-molecular weight compounds, organic ions, and the like. In addition, the fiber layer may contain, as optional components, surfactants, coupling agents, inorganic stratiform compounds, inorganic compounds, leveling agents, preservatives, antifoaming agents, organic particles, lubricants, antistatic agents, UV protection agents, It may contain one or more selected from dyes, pigments, stabilizers, magnetic powders, alignment promoters, plasticizers, dispersants and cross-linking agents.

The fiber layer may contain a hydrophilic polymer. Hydrophilic macromolecules generally refer to macromolecular compounds that are easily dissolved, swollen, or wetted by water. Hydrophilic polymers include polymer compounds having ionic groups such as carboxy groups, sulfone groups, or amino groups in the molecular structure, hydroxyl groups, amide groups, ether groups, polyoxyethylene groups, and polyoxypropylene groups. Polymer compounds having nonionic hydrophilic groups such as are exemplified. However, in this specification, the hydrophilic polymer does not include the fibrous cellulose described above.
Examples of hydrophilic polymers include carboxyvinyl polymer; polyvinyl alcohol; polyvinyl butyral; alkyl methacrylate/acrylic acid copolymer; polyvinylpyrrolidone; polyvinyl methyl ether; Coalescence; urethane copolymer; modified polyester; modified polyimide; polyethylene oxide; polyethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, etc. polycations such as polyacrylamide and polyethyleneimine; polyanions; zwitterionic polymers; xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince seed, alginic acid, metal salts of alginic acid, pullulan, and polysaccharide thickeners exemplified by pectin; cellulose derivatives exemplified by carboxymethylcellulose, methylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, and hydroxyethylcellulose; cationized starch, raw starch, oxidized starch, etherified Starches exemplified by starch, esterified starch, dextrin, and amylose; glycerins exemplified by polyglycerin; hyaluronic acid, metal salts of hyaluronic acid; and proteins exemplified by casein. can. Also, the hydrophilic polymer may be a copolymer of these hydrophilic polymers.

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

Examples of organic ions include tetraalkylammonium ions and tetraalkylphosphonium ions. Tetraalkylammonium ions include, for example, tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, tetraheptylammonium ion, tributylmethylammonium ion, lauryltrimethyl ammonium ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, octyldimethylethylammonium ion, lauryldimethylethylammonium ion, didecyldimethylammonium ion, lauryldimethylbenzylammonium ion, tributylbenzylammonium ion; Tetraalkylphosphonium ions include, for example, tetramethylphosphonium ion, tetraethylphosphonium ion, tetrapropylphosphonium ion, tetrabutylphosphonium ion, and lauryltrimethylphosphonium ion. Moreover, tetra-n-propylonium ion and tetra-n-butylonium ion can also be mentioned as examples of tetrapropylonium ion and tetrabutylonium ion, respectively.

The end of the fiber layer may be covered with a coating resin (cover resin). The resin species used for the coating resin can be the resin species used for the resin layer.

<Manufacturing process of fine fibrous cellulose>
<Textile raw material>
Microfibrous cellulose is produced from fibrous raw materials containing cellulose. The fibrous raw material containing cellulose is not particularly limited, but pulp is preferably used because it is readily available and inexpensive. Pulp includes, for example, wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include, but are not limited to, hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP). ) and chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemigroundwood pulp (CGP), groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP) A mechanical pulp etc. are mentioned. Non-wood pulps include, but are not limited to, cotton-based pulps such as cotton linters and cotton lints, and non-wood-based pulps such as hemp, straw, and bagasse. The deinked pulp is not particularly limited, but includes, for example, deinked pulp made from waste paper. The pulp of this embodiment may be used alone or in combination of two or more. Among the above pulps, wood pulp and deinked pulp are preferred, for example, from the viewpoint of availability. In addition, among wood pulps, the cellulose ratio is high and the yield of fine fibrous cellulose at the time of defibration is high, and the decomposition of cellulose in the pulp is small, and fine fibrous cellulose of long fibers with a large axial ratio can be obtained. From the point of view, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are more preferable.

As the fiber raw material containing cellulose, for example, cellulose contained in sea squirts and bacterial cellulose produced by acetic acid bacteria can be used. Fibers formed by straight-chain nitrogen-containing polysaccharide polymers such as chitin and chitosan can also be used instead of fiber raw materials containing cellulose.

In order to obtain fibrous cellulose into which ionic substituents have been introduced as described above, an ionic substituent introducing step of introducing ionic substituents into the fiber raw material containing cellulose described above, a washing step, an alkali treatment step (middle It is preferable to have a summing step) and a fibrillation treatment step in this order, and an acid treatment step may be provided instead of or in addition to the washing step. The ionic substituent introduction step includes a phosphorus oxoacid group introduction step, a carboxyl group introduction step, a sulfur oxoacid group introduction step, a xanthate group introduction step, a phosphonic group or phosphine group introduction step, a sulfone group introduction step, and a cationic group introduction step. A process is illustrated. Each of these will be described below.

<Phosphorus oxoacid group introduction step>
The step of producing fine fibrous cellulose preferably includes a step of introducing a phosphorus oxoacid group. In the phosphorus oxoacid group-introducing step, at least one compound selected from compounds capable of introducing a phosphorus oxoacid group (hereinafter also referred to as "compound A") is added to cellulose by reacting with a hydroxyl group possessed by a fiber raw material containing cellulose. It is a step of acting on a fiber raw material containing. Through this step, the phosphate group-introduced fiber is obtained.

In the phosphorus oxoacid group-introducing step according to the present embodiment, the reaction between the fiber material containing cellulose and compound A is performed in the presence of at least one selected from urea and derivatives thereof (hereinafter also referred to as "compound B"). may On the other hand, the reaction between the cellulose-containing fiber raw material and the compound A may be carried out in the absence of the compound B.

An example of the method of allowing the compound A to act on the fiber raw material in the presence of the compound B includes 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. Among these, 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, because the uniformity of the reaction is high. Although the form of the fiber material is not particularly limited, it is preferably in the form of cotton or a thin sheet, for example. The compound A and the compound B can be added to the fiber raw material in the form of a powder, a solution dissolved in a solvent, or a melted state by heating to a melting point or higher. Among these, it is preferable to add in the form of a solution dissolved in a solvent, particularly in the form of an aqueous solution, since the uniformity of the reaction is high. Moreover, the compound A and the compound B may be added simultaneously to the fiber raw material, 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 added dropwise to the Further, the necessary amount of compound A and compound B may be added to the fiber raw material, or after adding excessive amounts of compound A and compound B to the fiber raw material, the excess compound A and compound B are removed by pressing or filtering. may be removed.

The compound A used in the present embodiment may be any compound having a phosphorus atom and capable of forming an ester bond with cellulose. Salts, phosphoric anhydride (diphosphorus pentoxide) and the like can be mentioned, but are not particularly limited. Phosphoric acid of various purities can be used, for example, 100% phosphoric acid (orthophosphoric acid) or 85% phosphoric acid can be used. Phosphorous acid includes 99% phosphorous acid (phosphonic acid). Dehydration-condensed phosphoric acid is obtained by condensing two or more molecules of phosphoric acid by dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid. Phosphates, phosphites, and dehydrated condensed phosphates include lithium salts, sodium salts, potassium salts, and ammonium salts of phosphoric acid, phosphorous acid, or dehydrated condensed phosphoric acids. It can be a degree of harmony. Among these, phosphoric acid and sodium phosphate have a high introduction efficiency of a phosphate group, are easy to improve the defibration efficiency in the fibrillation step described later, are low in cost, and are easy to apply industrially. salt, potassium phosphate, ammonium phosphate or phosphorous acid, sodium phosphite, potassium phosphite, ammonium phosphite, phosphoric acid, sodium dihydrogen phosphate, More preferred are disodium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorous acid, and sodium phosphite.

The amount of compound A added to the fiber raw material is not particularly limited. For example, when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atoms 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 even more 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 amount of phosphorus atoms added to the fiber raw material to be equal to or less than the above upper limit, it is possible to balance the effect of improving the yield and the cost.

Compound B used in this embodiment is at least one selected from urea and derivatives thereof as described above. Compound B includes, for example, urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, and 1-ethylurea.
From the viewpoint of improving the uniformity of the reaction, compound B is preferably used as an aqueous solution. 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, more preferably 10% by mass or more and 400% by mass or less, More preferably, it is 100% by mass or more and 350% by mass or less.

In the reaction between the fiber raw material containing cellulose and compound A, in addition to compound B, for example, amides or amines may be included in the reaction system. Examples of amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine and hexamethylenediamine. Among these, triethylamine in particular is known to work as a good reaction catalyst.

In the phosphorus oxoacid group-introducing step, it is preferable to heat-treat the fiber raw material after adding or mixing the compound A or the like to the fiber raw material. As the heat treatment temperature, it is preferable to select a temperature that can efficiently introduce phosphorus oxoacid groups while suppressing 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 even more preferably 130° C. or higher and 200° C. or lower. In addition, for the heat treatment, equipment having various heat media can be used, for example, a stirring dryer, a rotary dryer, a disk dryer, a roll heater, a plate heater, a fluidized bed dryer, and a band dryer. A mold drying device, a filter drying device, a vibrating fluidized drying device, a flash 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, the compound A is added to a thin sheet-like fiber raw material by a method such as impregnation, and then heated, or the fiber raw material and the compound A are heated while kneading or stirring with a kneader or the like. method can be adopted. This makes it possible to suppress unevenness in the concentration of the compound A in the fiber raw material, and to more uniformly introduce the phosphorous acid groups to the surface of the cellulose fibers contained in the fiber raw material. This is because when water molecules move to the surface of the fiber material during drying, the dissolved compound A is attracted to the water molecules by surface tension and similarly moves to the surface of the fiber material (that is, the concentration unevenness of the compound A is It is thought that this is due to the fact that it is possible to suppress the occurrence of

In addition, the heating device used for the heat treatment always removes the moisture retained by the slurry and the moisture generated due to the dehydration condensation (phosphorylation) reaction between the compound A and the hydroxyl groups contained in the cellulose etc. in the fiber raw material. It is preferable that the device can be discharged to the outside of the device system. As such a heating device, for example, an air-blowing oven can be used. By constantly draining the water in the device system, it is possible to suppress the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of phosphorylation, and to suppress the acid hydrolysis of the sugar chains in the fiber. can. Therefore, it is possible to obtain fine fibrous cellulose having a high axial ratio.

The heat treatment time is, for example, 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 water is substantially removed from the fiber raw material. is more preferable. In the present embodiment, the amount of phosphorus oxoacid groups to be introduced can be set within a preferable range by setting the heating temperature and the heating time within appropriate ranges.

The phosphorus oxoacid group-introducing step may be performed at least once, but may be performed repeatedly two or more times. By performing the phosphorus oxoacid group-introducing step two or more times, many phosphorus oxoacid groups can be introduced into the fiber raw material.

The amount of phosphorus oxoacid groups introduced into the fiber raw material is, for example, preferably 0.05 mmol/g or more, more preferably 0.10 mmol/g or more, more preferably 0.20 mmol/g per 1 g (mass) of fine fibrous cellulose. g or more, more preferably 0.50 mmol/g or more, and particularly preferably 1.00 mmol/g or more. In addition, the amount of phosphorus oxoacid groups introduced into the fiber raw material is, for example, preferably 5.20 mmol/g or less, more preferably 3.65 mmol/g or less per 1 g (mass) of fine fibrous cellulose. It is more preferably 00 mmol/g or less. By setting the amount of the phosphorus oxoacid group to be introduced within the above range, the fiber raw material can be easily made finer, and the stability of the fine fibrous cellulose can be enhanced.

<Carboxy Group Introduction Step>
In the step of introducing a carboxy group, the fiber raw material containing cellulose is subjected to oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a carboxylic acid-derived group or a derivative thereof, or a carboxylic acid-derived group. This is done by treating the compound with an acid anhydride or a derivative thereof.

The compound having a carboxylic acid-derived group is not particularly limited. Examples include tricarboxylic acid compounds. Derivatives of compounds having a carboxylic acid-derived group are not particularly limited, but include, for example, imidized acid anhydrides of compounds having a carboxy group and derivatives of acid anhydrides of compounds having a carboxy group. Examples of imidized acid anhydrides of compounds having a carboxyl group include, but are not particularly limited to, imidized dicarboxylic acid compounds such as maleimide, succinimide and phthalimide.

The acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited. acid anhydrides; In addition, the acid anhydride derivative of the compound having a group derived from carboxylic acid is not particularly limited. Acid anhydrides in which at least some of the hydrogen atoms are substituted with substituents such as alkyl groups and phenyl groups can be mentioned.

In the carboxyl group introduction step, when the TEMPO oxidation treatment is performed, it is preferable to perform the treatment under the condition of pH 6 or more and 8 or less. Such treatment is also referred to as neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH=6.8), pulp as a fiber raw material, and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a catalyst. This can be done by adding sodium hypochlorite as a nitroxy radical, sacrificial reagent. Furthermore, coexistence of sodium chlorite enables efficient oxidation of aldehydes generated in the process of oxidation to carboxyl groups. Moreover, the TEMPO oxidation treatment may be performed under the condition that the pH is 10 or more and 11 or less. Such treatment is also called alkali TEMPO oxidation treatment. Alkaline TEMPO oxidation treatment can be performed, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a cocatalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. .

The amount of carboxyl groups to be introduced into the fiber raw material varies depending on the type of substituent. For example, when carboxyl groups are introduced by TEMPO oxidation, the amount is preferably 0.05 mmol/g or more per 1 g (mass) of fine fibrous cellulose. , more preferably 0.10 mmol/g or more, more preferably 0.20 mmol/g or more, still more preferably 0.50 mmol/g or more, and 0.90 mmol/g or more Especially preferred. Also, it is preferably 2.5 mmol/g or less, more preferably 2.20 mmol/g or less, and even more 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.

<Sulfur oxoacid group introduction step>
The step of producing fine fibrous cellulose may include a step of introducing a sulfur oxoacid group as the step of introducing an ionic group. In the step of introducing sulfur oxo acid groups, cellulose fibers having sulfur oxo acid groups (sulfur oxo acid group-introduced fibers) can be obtained by reacting hydroxyl groups of the fiber raw material containing cellulose with sulfur oxo acids.

In the sulfur oxoacid group-introducing step, instead of the compound A in the <phosphorus oxoacid group-introducing step> described above, a compound that can introduce a sulfur oxoacid group by reacting with a hydroxyl group possessed by a fiber raw material containing cellulose is selected. At least one compound (hereinafter also referred to as "compound C") is used. Compound C is not particularly limited as long as it has a sulfur atom and is capable of forming an ester bond with cellulose, and includes sulfuric acid or its salts, sulfurous acid or its salts, and sulfate amides. Sulfuric acid of various purities can be used, for example, 96% sulfuric acid (concentrated sulfuric acid) can be used. Sulfurous acid includes 5% sulfurous acid water. Sulfates or sulfites include lithium, sodium, potassium, ammonium salts, etc. of sulfates or sulfites, which can be of varying degrees of neutralization. As the sulfate amide, sulfamic acid or the like can be used. In the sulfur oxoacid group-introducing step, it is preferable to use compound B in the same manner as in <phosphorus oxoacid group-introducing step>.

In the step of introducing sulfur oxoacid groups, it is preferable to heat-treat the cellulose raw material after mixing the cellulose raw material with an aqueous solution containing sulfur oxoacid and urea and/or a urea derivative. As the heat treatment temperature, it is preferable to select a temperature at which sulfur oxoacid groups can be efficiently introduced while suppressing thermal decomposition and hydrolysis reaction of the fiber. The heat treatment temperature is preferably 100° C. or higher, more preferably 120° C. or higher, and even more preferably 150° C. or higher. The heat treatment temperature is preferably 300° C. or lower, more preferably 250° C. or lower, and even more preferably 200° C. or lower.

In the heat treatment step, it is preferable to heat until the moisture is substantially removed. For this reason, the heat treatment time varies depending on the amount of water contained in the cellulose raw material, sulfur oxo acid, and the added amount of the aqueous solution containing urea and/or urea derivatives, but for example, 10 seconds or more and 10000 seconds or less. preferably. Equipment having various heat media can be used for the heat treatment, for example, a stirring dryer, a rotary dryer, a disk dryer, a roll heater, a plate heater, a fluidized bed dryer, and a band dryer. An apparatus, filter drying apparatus, vibrating fluidized drying apparatus, air flow drying apparatus, vacuum drying apparatus, infrared heating apparatus, far infrared heating apparatus, microwave heating apparatus, and high frequency drying apparatus can be used.

The amount of sulfur oxo acid groups introduced in the step of introducing sulfur oxo acid groups is preferably 0.05 mmol/g or more, more preferably 0.10 mmol/g or more, per 1 g (mass) of fiber raw material. It is more preferably 20 mmol/g or more, and particularly preferably 0.50 mmol/g or more. The amount of sulfur oxoacid groups introduced is, for example, preferably 5.00 mmol/g or less, more preferably 3.00 mmol/g or less per 1 g (mass) of fiber raw material. By setting the amount of the sulfur oxoacid group to be introduced within the above range, the cellulose fibers can be easily made finer in the finer processing step, and the stability of the fine fibrous cellulose can be enhanced.

<Xanthate Group Introduction Step>
The step of producing fine fibrous cellulose may include a step of introducing a xanthate group as the step of introducing an ionic substituent. In the xanthate group-introducing step, a cellulose fiber having a xanthate group (a xanthate group-introduced fiber) is obtained by substituting a xanthate group represented by the following formula (3) for a hydroxyl group of a fiber raw material containing cellulose.
- OCSS ^- M ⁺ (3)
Here, M ⁺ is at least one selected from hydrogen ions, monovalent metal ions, ammonium ions, and aliphatic or aromatic ammonium ions.

In the xanthate group-introducing step, first, alkali treatment is performed to treat the fiber raw material containing cellulose with an alkali solution to obtain alkali cellulose. Examples of the alkaline solution include an aqueous alkali metal hydroxide solution and an aqueous alkaline earth metal hydroxide solution. Among them, the alkaline solution is preferably an aqueous alkali metal hydroxide solution such as sodium hydroxide or potassium hydroxide, and particularly preferably an aqueous sodium hydroxide solution. When the alkaline solution is an aqueous alkali metal hydroxide solution, the concentration of the alkali metal hydroxide in the aqueous alkali metal hydroxide solution is preferably 4% by mass or more, more preferably 5% by mass or more. Further, the alkali metal hydroxide concentration in the aqueous alkali metal hydroxide solution is preferably 9% by mass or less. By setting the alkali metal hydroxide concentration to the above lower limit or more, cellulose mercerization can be sufficiently advanced, and the amount of by-products generated during the subsequent xanthate formation can be reduced. As a result, The yield of the xanthate group-introduced fiber can be increased. Thereby, the fibrillation process mentioned later can be performed more effectively. In addition, by setting the alkali metal hydroxide concentration to the above upper limit or less, it is possible to suppress the penetration of the aqueous alkali metal hydroxide solution into the crystalline region of cellulose while promoting mercerization. The crystalline structure of the mold is easily maintained, and the yield of fine fibrous cellulose can be further increased.

The alkali treatment time is preferably 30 minutes or longer, more preferably 1 hour or longer. Also, the alkali treatment time is preferably 6 hours or less, more preferably 5 hours or less. By setting the alkali treatment time within the above range, the final yield can be increased and the productivity can be increased.

It is preferable that the alkali cellulose obtained by the alkali treatment is then subjected to solid-liquid separation to remove as much of the aqueous solution as possible. As a result, the water content during the subsequent xanthate treatment can be reduced, and the reaction can be promoted. As a solid-liquid separation method, a general dehydration method such as centrifugation or filtration can be used. The concentration of the alkali metal hydroxide contained in the alkali cellulose after solid-liquid separation is preferably 3% by mass or more and 8% by mass or less with respect to the total mass of the alkali cellulose after solid-liquid separation.

In the xanthate group-introducing step, the xanthate-forming treatment step is performed after the alkali treatment. In the xanthate treatment step, alkali cellulose is reacted with carbon disulfide (CS ₂ ) to convert (-O ^- Na ⁺ ) groups to (-OCSS ^- Na ⁺ ) groups to obtain xanthate group-introduced fibers. In the above description, the metal ions introduced into the alkali cellulose are represented by Na ⁺ , but similar reactions proceed with other alkali metal ions.

In the xanthate treatment, it is preferable to supply 10% by mass or more of carbon disulfide with respect to the absolute dry mass of cellulose in the alkali cellulose. In addition, in the xanthate-forming treatment, the contact time between carbon disulfide and alkali cellulose is preferably 30 minutes or longer, more preferably 1 hour or longer. Xanthate formation proceeds rapidly when carbon disulfide comes into contact with alkali cellulose, but it takes time for carbon disulfide to penetrate into the interior of alkali cellulose, so the reaction time is preferably within the above range. On the other hand, the contact time between the carbon disulfide and the alkali cellulose should be 6 hours or less, whereby the alkali cellulose mass after dehydration is sufficiently permeated, and the reactable xanthate is almost completely formed. can be completed.

The reaction temperature in the xanthate-forming treatment is preferably 46° C. or lower. By setting the reaction temperature within the above range, decomposition of alkali cellulose can be easily suppressed. Further, by setting the reaction temperature within the above range, uniform reaction is facilitated, so that the generation of by-products can be suppressed, and furthermore, the removal of the generated xanthate groups can be suppressed.

<Oxidation step with chlorine-based oxidizing agent (second carboxyl group introduction step)>
The step of introducing an ionic substituent may include an oxidation step using a chlorine-based oxidizing agent. In the oxidation step using a chlorine-based oxidizing agent, a carboxyl group is introduced into the fiber raw material by adding the chlorine-based oxidizing agent to a fiber raw material having hydroxyl groups in a wet or dry state and performing a reaction.

Examples of chlorine-based oxidizing agents include hypochlorous acid, hypochlorite, chlorous acid, chlorite, chloric acid, chlorate, perchloric acid, perchlorate, and chlorine dioxide. The chlorine-based oxidizing agent is preferably sodium hypochlorite, sodium chlorite, or chlorine dioxide from the viewpoints of introduction efficiency of substituents, defibration efficiency, cost, and ease of handling. When the chlorine-based oxidizing agent is added, it may be added as a reagent (solid or liquid) to the fiber raw material as it is, or it may be dissolved in an appropriate solvent and added.

The concentration of the chlorine-based oxidizing agent in the solution in the oxidation step using the chlorine-based oxidizing agent is preferably 1% by mass or more and 1,000% by mass or less, and is preferably 5% by mass or more and 500% by mass in terms of effective chlorine concentration. It is more preferably 10% by mass or more and 100% by mass or less. The amount of the chlorine-based oxidizing agent added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 10 parts by mass or more and 10,000 parts by mass or less, and 100 parts by mass. It is more preferable that the content is 5,000 parts by mass or more and 5,000 parts by mass or less.

The reaction time with the chlorine-based oxidizing agent in the oxidation step with the chlorine-based oxidizing agent may vary depending on the reaction temperature, but is preferably, for example, 1 minute or more and 1,000 minutes or less, and 10 minutes or more and 500 minutes or less. More preferably, the time is 20 minutes or more and 400 minutes or less. The pH during the reaction is preferably 5 or more and 15 or less, more preferably 7 or more and 14 or less, and even more preferably 9 or more and 13 or less. Moreover, at the start of the reaction, the pH during the reaction is preferably kept constant (for example, pH 11) by appropriately adding hydrochloric acid or sodium hydroxide. After the reaction, excess reaction reagents, by-products and the like may be washed with water and removed by filtration or the like.

<Phosphonic group or phosphine group introduction step (phosphoalkylation step)>
The step of introducing an ionic substituent may include a step of introducing a phosphone group or a phosphine group (phosphoalkylation step). In the phosphoalkylation step, a compound having a reactive group and a phospho group or a phosphine group (compound E _A ) as an essential component, an alkali compound as an optional component, and a compound B selected from the aforementioned urea and its derivatives are wetted. Alternatively, a phosphonic group or a phosphine group is introduced into the fiber raw material by adding it to the fiber raw material having hydroxyl groups in a dry state and performing a reaction.

Examples of reactive groups include halogenated alkyl groups, vinyl groups, epoxy groups (glycidyl groups), and the like.
Compound EA includes, for example, _{vinylphosphonic} acid, phenylvinylphosphonic acid, phenylvinylphosphinic acid and the like. Compound EA is preferably _{vinylphosphonic} acid from the viewpoints of the efficiency of introduction of substituents, the efficiency of fibrillation, the cost, and the ease of handling.
Furthermore, as an optional component, it is preferable to use compound B in the same manner as in the above-described <Phosphorus oxoacid group-introducing step>, and the amount added is preferably as described above.

When compound _EA is added, it may be added as a reagent (solid or liquid) to the fiber raw material as it is, or it may be dissolved in an appropriate solvent and added. It is preferable that the fiber raw material is converted to alkali cellulose in advance or is converted to alkali cellulose simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The temperature during the reaction is, for example, preferably 50° C. or higher and 300° C. or lower, more preferably 100° C. or higher and 250° C. or lower, even more preferably 130° C. or higher and 200° C. or lower.

The amount of Compound E _A added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and 5 parts by mass. It is more preferable that the amount is 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably, for example, 1 minute or more and 1,000 minutes or less, more preferably 10 minutes or more and 500 minutes or less, and 20 minutes or more and 400 minutes or less. is more preferred. After the reaction, excess reaction reagents, by-products and the like may be washed with water and removed by filtration or the like.

<Sulfone group introduction step (sulfoalkylation step)>
The ionic substituent introduction step may include a sulfone group introduction step (sulfoalkylation step). In the sulfoalkylation, a compound (compound E _B ) having a reactive group and a sulfone group as essential components, an alkali compound as an optional component, and a compound B selected from the above-mentioned urea and its derivatives are mixed in a wet or dry state. The sulfone group is introduced into the fiber raw material by reacting with the fiber raw material having a hydroxyl group.

Examples of reactive groups include halogenated alkyl groups, vinyl groups, epoxy groups (glycidyl groups), and the like.
Compound E _B includes sodium 2-chloroethanesulfonate, sodium vinylsulfonate, sodium p-styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid and the like. Above all, the compound _EB is preferably sodium vinyl sulfonate from the viewpoints of the efficiency of introduction of substituents, the efficiency of fibrillation, the cost, and the ease of handling. Furthermore, as an optional component, it is preferable to use compound B in the same manner as in the above-described <Phosphorus oxoacid group-introducing step>, and the amount added is preferably as described above.

When compound _EB is added, it may be added as a reagent (solid or liquid) to the fiber raw material as it is, or it may be dissolved in an appropriate solvent and added. It is preferable that the fiber raw material is converted to alkali cellulose in advance or is converted to alkali cellulose simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The temperature during the reaction is, for example, preferably 50° C. or higher and 300° C. or lower, more preferably 100° C. or higher and 250° C. or lower, even more preferably 130° C. or higher and 200° C. or lower.

The amount of Compound E _B added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and 5 parts by mass. It is more preferable that the amount is 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably, for example, 1 minute or more and 1,000 minutes or less, more preferably 10 minutes or more and 500 minutes or less, and 15 minutes or more and 400 minutes or less. is more preferred. After the reaction, excess reaction reagents, by-products and the like may be washed with water and removed by filtration or the like.

<Carboxyalkylation step (third carboxy group introduction step)>
The ionic substituent introduction step may include a carboxyalkylation step. A compound having a reactive group and a carboxyl group (compound E _C ) as an essential component, an alkali compound as an optional component, and a compound B selected from the above-mentioned urea and its derivatives are added to a fiber having a hydroxyl group in a wet or dry state. A carboxyl group is introduced into the fiber raw material by adding it to the raw material and reacting it.

Examples of reactive groups include halogenated alkyl groups, vinyl groups, epoxy groups (glycidyl groups), and the like.
As the compound E _C , monochloroacetic acid, sodium monochloroacetate, 2-chloropropionic acid, 3-chloropropionic acid, and sodium 2-chloropropionate can be used from the viewpoints of introduction efficiency of substituents, and thus fibrillation efficiency, cost, and ease of handling. , sodium 3-chloropropionate is preferred. Furthermore, as an optional component, it is preferable to use compound B in the same manner as in the above-described <Phosphorus oxoacid group-introducing step>, and the amount added is preferably as described above.

When compound E _C is added, it may be added as a reagent (solid or liquid) to the fiber raw material as it is, or it may be dissolved in an appropriate solvent and added. It is preferable that the fiber raw material is converted to alkali cellulose in advance or is converted to alkali cellulose simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The temperature during the reaction is, for example, preferably 50° C. or higher and 300° C. or lower, more preferably 100° C. or higher and 250° C. or lower, even more preferably 130° C. or higher and 200° C. or lower.

The amount of the compound _E to be added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and 5 parts by mass. It is more preferable that the amount is 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably, for example, 1 minute or more and 1,000 minutes or less, more preferably 3 minutes or more and 500 minutes or less, and 5 minutes or more and 400 minutes or less. is more preferred. After the reaction, excess reaction reagents, by-products and the like may be washed with water and removed by filtration or the like.

<Cationic group introduction step (cationization step)>
A compound having a reactive group and a cationic group (compound E _D ) as an essential component, an alkali compound as an optional component, and a compound B selected from the above-mentioned urea and its derivatives, in a wet or dry state, having a hydroxyl group A cationic group is introduced into the fiber raw material by performing a reaction in addition to the fiber raw material.

Examples of reactive groups include halogenated alkyl groups, vinyl groups, epoxy groups (glycidyl groups), and the like.
Cationic groups include an ammonium group, a phosphonium group, a sulfonium group, and the like. Among them, the cationic group is preferably an ammonium group.
As the compound E _D , glycidyltrimethylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride, and the like are preferable from the viewpoints of introduction efficiency of substituents, defibration efficiency, cost, and ease of handling.
Furthermore, as an optional component, it is also preferable to use compound B in the above-described <Phosphorus oxoacid group-introducing step> in the same manner. It is preferable that the amount to be added is also as described above.

When compound E _D is added, it may be added as it is as a reagent (solid or liquid) to the fiber raw material, or it may be added after being dissolved in an appropriate solvent. It is preferable that the fiber raw material is converted to alkali cellulose in advance or is converted to alkali cellulose simultaneously with the reaction. The method of alkali cellulose conversion is as described above.

The temperature during the reaction is, for example, preferably 50° C. or higher and 300° C. or lower, more preferably 100° C. or higher and 250° C. or lower, even more preferably 130° C. or higher and 200° C. or lower.

The amount of compound E _D added to 100 parts by mass of the fiber raw material is preferably 1 part by mass or more and 100,000 parts by mass or less, more preferably 2 parts by mass or more and 10,000 parts by mass or less, and 5 parts by mass. It is more preferable that the amount is 1,000 parts by mass or less.

The reaction time may vary depending on the reaction temperature, but is preferably, for example, 1 minute or more and 1,000 minutes or less, more preferably 5 minutes or more and 500 minutes or less, and 10 minutes or more and 400 minutes or less. is more preferred. After the reaction, excess reaction reagents, by-products and the like may be washed with water and removed by filtration or the like.

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

<Alkali treatment process>
When producing fine fibrous cellulose, the fiber raw material may be subjected to alkali treatment between the ionic substituent introduction step and the fibrillation treatment step described later. The method of alkali treatment is not particularly limited, but includes, for example, a method of immersing the ionic substituent-introduced fiber in an alkali 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, it is preferable to use, for example, sodium hydroxide or potassium hydroxide as the alkaline compound because of its high versatility. Moreover, 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 water or a polar solvent including a polar organic solvent exemplified by alcohol, and more preferably an aqueous solvent including at least water. As the alkaline solution, for example, an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution is preferable because of its high versatility.

Although the temperature of the alkaline solution in the alkaline treatment step is not particularly limited, it is preferably 5° C. or higher and 80° C. or lower, more preferably 10° C. or higher and 60° C. or lower. The immersion time of the phosphooxyacid group-introduced fiber in the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, more preferably 10 minutes or more and 20 minutes or less. The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but for example, it is preferably 100% by mass or more and 100000% by mass or less, and 1000% by mass or more and 10000% by mass or less based on the absolute dry mass of the phosphooxyacid group-introduced fiber. is more preferable.

In order to reduce the amount of alkaline solution used in the alkali treatment step, the phosphate group-introduced 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 fibrillation treatment step, it is preferable to wash the alkali-treated ionic substituent-introduced fibers with water or an organic solvent from the viewpoint of improving handleability.

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

The acid treatment method is not particularly limited, but includes, for example, a method of immersing the fiber raw material in an acidic liquid containing an acid. Although the concentration of the acid liquid used is not particularly limited, it is preferably 10% by mass or less, more preferably 5% by mass or less. Moreover, the pH of the acidic liquid to be used is not particularly limited. Examples of acids contained in the acid solution include inorganic acids, sulfonic acids, and carboxylic acids. Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, phosphoric acid and boric acid. Examples of sulfonic acid include methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid and the like. Carboxylic acids include, for example, formic acid, acetic acid, citric acid, gluconic acid, lactic acid, oxalic acid, and tartaric acid. 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. 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, 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. is more preferred.

<Fibrillation treatment>
By defibrating the ionic substituent-introduced fibers in the fibrillation treatment step, fine fibrous cellulose can be obtained. In the defibration treatment process, for example, a fibrillation treatment device can be used. The fibrillation treatment device is not particularly limited, but for example, a high-speed fibrillator, a grinder (stone mill type pulverizer), a high pressure homogenizer, an ultra-high pressure homogenizer, a high pressure impact type pulverizer, a ball mill, a bead mill, a disk refiner, a conical refiner, and a biaxial refiner. A kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, a beater, or the like can be used. Among the above defibration equipment, it is more preferable to use a high-speed fibrillation machine, a high-pressure homogenizer, and an ultrahigh-pressure homogenizer, which are less affected by the grinding media and less likely to cause contamination.

In the fibrillation treatment step, for example, the ionic substituent-introduced fibers are preferably diluted with a dispersion medium to form a slurry. As the dispersion medium, one or more selected from organic solvents such as water and polar organic solvents can be used. The polar organic solvent is not particularly limited, but 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 and glycerin. 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 esters include ethyl acetate and butyl acetate. Aprotic polar solvents include dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and the like.

The solid content concentration of the fine fibrous cellulose at the defibration treatment can be appropriately set. Further, the slurry obtained by dispersing the ionic substituent-introduced fiber in the dispersion medium may contain solids other than the phosphorus oxoacid group-introduced fiber, such as urea having hydrogen bonding properties.

<Nitrogen removal treatment>
The step of producing fine fibrous cellulose may further include a step of reducing the amount of nitrogen (nitrogen removal treatment step). By reducing the nitrogen content, it is possible to obtain fine fibrous cellulose that can further suppress coloration. The nitrogen removal treatment step is preferably provided before the fibrillation treatment step.

In the nitrogen removal treatment step, it is preferable to adjust the pH of the slurry containing the substituent-introduced fiber to 10 or more and perform heat treatment. In the heat treatment, the liquid temperature of the slurry is preferably 50° C. or higher and 100° C. or lower, and the heating time is preferably 15 minutes or longer and 180 minutes or shorter. When adjusting the pH of the slurry containing the substituent-introduced fiber, it is preferable to add an alkali compound that can be used in the alkali treatment step described above to the slurry.

After the nitrogen removal treatment step, the substituent-introduced fiber can be subjected to a washing step, if necessary. The washing step is performed by washing the ionic substituent-introduced fiber with, for example, water or an organic solvent. Moreover, the number of washings performed in each washing step is not particularly limited.

<Substituent removal treatment>
The method for producing fine fibrous cellulose may include a step of removing at least part of the substituent from fine fibrous cellulose having a substituent and having a fiber width of 1000 nm or less. Through such steps, it is possible to obtain fine fibrous cellulose with a small fiber width, although the amount of substituent introduced is low. In this specification, the step of removing at least part of the substituents from the fine fibrous cellulose is also referred to as a substituent removal treatment step.

Examples of the substituent-removing treatment step include a step of heat-treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, an enzyme treatment step, an acid treatment step, an alkali treatment step, and the like. These may be carried out singly or in combination. Among them, the substituent removal treatment step is preferably a heat treatment step or an enzyme treatment step. By going through the above treatment step, at least part of the substituent is removed from the fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, and a fine fiber having a substituent introduction amount of less than 0.5 mmol / g is obtained. A fibrous cellulose can be obtained.

The substituent removal treatment step is preferably performed in a slurry state. That is, in the substituent removal treatment step, a slurry containing fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less is subjected to heat treatment, enzyme treatment, acid treatment, and alkali treatment. etc. is preferable. By carrying out the substituent removal treatment step in a slurry form, it is possible to prevent residual coloring substances caused by heating or the like during the substituent removal treatment, and added or generated acids, alkalis, salts, and the like. Thereby, coloring of a fiber layer and a resin molding can be suppressed. In addition, when the salt derived from the removed substituent is removed after the substituent removal treatment, it is possible to increase the salt removal efficiency.

When a slurry containing fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less is subjected to the substituent removal treatment, the concentration of the fine fibrous cellulose in the slurry is 0.05% by mass or more. It is preferably 0.1% by mass or more, more preferably 0.2% by mass or more. The concentration of fine fibrous cellulose in the slurry is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. By setting the concentration of the fine fibrous cellulose in the slurry within the above range, the substituent removal treatment can be performed more efficiently. Furthermore, by setting the concentration of the fine fibrous cellulose in the slurry within the above range, it is possible to prevent the residual coloring matter caused by heating during the substituent removal treatment, and the acid, alkali, salt, etc. added or generated. can. Thereby, coloring of a fiber layer and a resin molding can be suppressed. In addition, when the salt derived from the removed substituent is removed after the substituent removal treatment, it is possible to increase the salt removal efficiency.

When the substituent-removing treatment step is a step of heat-treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, the heating temperature in the heat-treating step is preferably 40° C. or higher. , more preferably 50° C. or higher, and even more preferably 60° C. or higher. The heating temperature in the heat treatment step is preferably 250° C. or lower, more preferably 230° C. or lower, and even more preferably 200° C. or lower. Above all, when the substituent of the fine fibrous cellulose to be subjected to the substituent removal treatment step is a phosphorous acid group, the heating temperature in the heat treatment step is preferably 80° C. or higher, more preferably 100° C. or higher. More preferably, it is 120° C. or higher.

When the substituent removal treatment step is a heat treatment step, the heating device that can be used in the heat treatment step is not particularly limited, but hot air heating device, steam heating device, electric heating device, hydrothermal heating device, thermal heating device. , infrared heating device, far infrared heating device, microwave heating device, high frequency heating device, stirring drying device, rotary drying device, disk drying device, roll type heating device, plate type heating device, fluidized bed drying device, band type drying device , a filtration drying apparatus, a vibrating fluidized drying apparatus, a flash drying apparatus, and a vacuum drying apparatus can be used. From the viewpoint of preventing evaporation, the heating is preferably performed in a closed system, and from the viewpoint of increasing the heating temperature, it is preferably performed in a pressure-resistant device or container. The heat treatment may be batch treatment, batch continuous treatment, or continuous treatment.

When the substituent removal treatment step is a step of enzymatically treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, in the enzymatic treatment step, depending on the type of substituent, phosphate ester It is preferable to use a hydrolase, a sulfate ester hydrolase, or the like.

In the enzymatic treatment step, the enzyme is preferably added so that the enzyme activity per 1 g of fine fibrous cellulose is 0.1 nkat or more, more preferably 1.0 nkat or more, and 10 nkat or more. It is more preferable to add the enzyme so that the Further, the enzyme is preferably added so that the enzyme activity is 100,000 nkat or less, more preferably 50,000 nkat or less, per 1 g of fine fibrous cellulose, and more preferably 10,000 nkat or less. More preferred. After adding the enzyme to the fine fibrous cellulose dispersion (slurry), it is preferable to carry out the treatment at a temperature of 0° C. or more and less than 50° C. for 1 minute or more and 100 hours or less.

A step of deactivating the enzyme may be provided after the enzymatic reaction. As a method for deactivating the enzyme, an acid component or an alkaline component is added to the enzyme-treated slurry to deactivate the enzyme. A method of deactivation can be mentioned.

When the substituent-removing treatment step is a step of acid-treating fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, the acid-treating step includes acid that can be used in the acid treatment step described above. It is preferred to add the compound to the slurry.

When the substituent-removing treatment step is a step of treating with an alkali fine fibrous cellulose having a substituent and a fiber width of 1000 nm or less, the step of treating with an alkali includes an alkali that can be used in the above-described alkali treatment step. It is preferred to add the compound to the slurry.

In the substituent-removing treatment step, it is preferable that the substituent-removing reaction proceed uniformly. In order to proceed the reaction uniformly, for example, the slurry containing fine fibrous cellulose may be stirred, or the specific surface area of the slurry may be increased. As a method for agitating the slurry, a mechanical shear may be applied from the outside, or the self-agitation may be promoted by increasing the feeding speed of the slurry during the reaction.

A spacer molecule may be added in the substituent removal treatment step. Spacer molecules act as spacers to get between adjacent fibrous celluloses, thereby providing fine spaces between the fine fibrous celluloses. By adding such a spacer molecule in the substituent-removing treatment step, aggregation of the fine fibrous cellulose after the substituent-removing treatment can be suppressed. Thereby, the transparency of the fiber layer and the resin molding can be more effectively improved.

Preferably, the spacer molecule is a water-soluble organic compound. Examples of water-soluble organic compounds include sugars, water-soluble polymers, and urea. Specifically, trehalose, urea, polyethylene glycol (PEG), polyethylene oxide (PEO), carboxymethylcellulose, polyvinyl alcohol (PVA) and the like can be mentioned. Examples of water-soluble organic compounds include alkyl methacrylate/acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, and polyacrylamide. , xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince seed, alginic acid, pullulan, carrageenan, pectin, cationic starch, raw starch, oxidized starch, etherified starch, esterified starch, starches such as amylose, glycerin , diglycerin, polyglycerin, hyaluronic acid, and metal salts of hyaluronic acid can also be used.

Also, known pigments can be used as spacer molecules. For example, kaolin (including clay), calcium carbonate, titanium oxide, zinc oxide, amorphous silica (including colloidal silica), aluminum oxide, zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, Examples include styrene plastic pigments, hydrotalcite, urea resin plastic pigments, benzoguanamine plastic pigments, and the like.

<pH adjustment step>
When the above-described substituent-removing treatment step is performed in the form of a slurry, a step of adjusting the pH of the slurry containing fine fibrous cellulose may be provided before the substituent-removing treatment step. For example, when an ionic substituent is introduced into cellulose fibers and the counter ion of this ionic substituent is Na + , the slurry containing fine fibrous cellulose after fibrillation exhibits weak alkalinity. If heating is performed in this state, monosaccharides, which are one of the coloring factors, may be generated due to decomposition of cellulose, so it is preferable to adjust the pH of the slurry to 8 or less, more preferably 6 or less. preferable. In addition, since monosaccharides may also be generated under acidic conditions, the pH of the slurry is preferably adjusted to 3 or higher, more preferably 4 or higher.

Further, when the fine fibrous cellulose having a substituent is a fine fibrous cellulose having a phosphate group, from the viewpoint of improving the efficiency of removing the substituent, phosphorus of the phosphate group should be in a state of being susceptible to nucleophilic attack. is preferred. Cellulose -OP (=O) (-OH ⁺ ) (-O-Na ⁺ ) with a degree of neutralization of 1 is susceptible to nucleophilic attack. Preferably, the pH of the slurry is adjusted to 3 or more and 8 or less, more preferably 4 or more and 6 or less.

Means for adjusting the pH are not particularly limited, but for example, an acid component or an alkali component may be added to the slurry containing fine fibrous cellulose. The acid component may be either an inorganic acid or an organic acid. Examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid. Organic acids include formic acid, acetic acid, citric acid, malic acid, lactic acid, adipic acid, sebacic acid, stearic acid, maleic acid, succinic acid, tartaric acid, fumaric acid, gluconic acid and the like. The alkali component may be an inorganic alkali compound or an organic alkali compound. Examples of inorganic alkali compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, lithium carbonate, lithium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, sodium carbonate, and sodium hydrogen carbonate. Organic alkaline compounds include ammonia, hydrazine, methylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, diaminoethane, diaminopropane, diaminobutane, diaminopentane, diaminohexane, cyclohexylamine, aniline, tetramethyl ammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, pyridine, N,N-dimethyl-4-aminopyridine and the like.

Moreover, in the pH adjustment step, an ion exchange treatment may be performed in order to adjust the pH. For the ion exchange treatment, a strongly acidic cation exchange resin or a weakly acidic ion exchange resin can be used. By treating with an appropriate amount of cation exchange resin for a sufficient period of time, a slurry containing fine fibrous cellulose at a desired pH can be obtained. Furthermore, in the pH adjustment step, the addition of an acid component or an alkali component and the ion exchange treatment may be combined.

<Salt Removal Treatment>
After the substituent-removing treatment step, it is preferable to perform a treatment for removing salts derived from the removed substituents. By removing the salt derived from the substituent, it becomes easier to obtain fine fibrous cellulose capable of suppressing coloration. Although the means for removing the salt derived from the substituent is not particularly limited, washing treatment can be mentioned, for example. The washing treatment is performed, for example, by washing the fine fibrous cellulose aggregated by the substituent removal treatment with water or an organic solvent. From the viewpoint of more effectively suppressing yellowing, the washing treatment is preferably performed by filtration dehydration, centrifugal dehydration, or centrifugation.

<Uniform dispersion treatment>
After the substituent-removing treatment step, a step of uniformly dispersing the fine fibrous cellulose obtained through the substituent-removing treatment may be provided. By subjecting the fine fibrous cellulose to the substituent-removing treatment, at least a part of the fine fibrous cellulose aggregates. The uniformly dispersing treatment step is a step of uniformly dispersing the aggregated fine fibrous cellulose.

In the uniform dispersion treatment process, for example, high-speed fibrillation machine, grinder (stone mill type crusher), high pressure homogenizer, high pressure collision type crusher, ball mill, bead mill, disc refiner, conical refiner, twin screw kneader, vibration mill, under high speed rotation A homomixer, an ultrasonic disperser, a beater, or the like can be used. Among the uniform dispersion treatment apparatuses, it is more preferable to use a high-speed defibrator and a high-pressure homogenizer.

The treatment conditions in the uniform dispersion treatment step are not particularly limited, but it is preferable to increase the maximum moving speed of the fine fibrous cellulose during treatment and the pressure during treatment. The peripheral speed of the high-speed defibrator is preferably 20 m/sec or higher, more preferably 25 m/sec or higher, and even more preferably 30 m/sec or higher. A high-pressure homogenizer can be used more preferably than a high-speed defibrator because the maximum moving speed of fine fibrous cellulose during treatment and the pressure during treatment are higher. In the high-pressure homogenizer treatment, the pressure during treatment is preferably 1 MPa or more and 350 MPa or less, more preferably 10 MPa or more and 300 MPa or less, and even more preferably 50 MPa or more and 250 MPa or less.

In addition, in the uniform dispersion treatment step, the spacer molecules described above may be newly added. By adding such a spacer molecule in the uniform dispersion treatment step, uniform dispersion of the fine fibrous cellulose can be carried out more smoothly. Thereby, the transparency of the fiber layer and the resin molding can be more effectively improved.

<Manufacturing process of fiber layer (sheet containing fine fibrous cellulose)>
As a method for producing the fiber layer, for example, the fine fibrous cellulose-containing slurry (dispersion) obtained through the above steps is paper-made or coated (coated), and dried to form a fine fibrous cellulose-containing sheet. method. The fine fibrous cellulose-containing sheet constitutes the fiber layer in the resin molding.

Preferably, the slurry used in the manufacturing process of the fiber layer further contains, for example, a hydrophilic polymer. This can further improve the transparency and mechanical strength of the fiber layer. The hydrophilic polymer may contain, for example, one or more selected from those exemplified above.

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

The material of the base material used in the coating step is not particularly limited, but a material with high wettability to the composition (slurry) can suppress the shrinkage of the sheet during drying, but it is formed after drying. It is preferable to select a sheet from which the sheet can be easily peeled off. Among them, 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 such as aluminum, zinc, copper, and iron plates, and those whose surfaces have been oxidized. , a stainless steel film or plate, a brass film or plate, or the like can be used.

In the coating process, when the viscosity of the slurry is low and it spreads on the base material, a dam frame is fixed on the base material in order to obtain a sheet with a predetermined thickness and basis weight. may The frame for damming is not particularly limited, but it is preferable to select, for example, one that allows easy peeling of the edge of the sheet that adheres after drying. From such a point of view, a molded resin plate or metal plate is more preferable. In the present embodiment, for example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polypropylene plates, polycarbonate plates, and polyvinylidene chloride plates, and metal plates such as aluminum plates, zinc plates, copper plates, iron plates, etc. , and those whose surfaces have been oxidized, and those obtained by molding a stainless steel plate, a brass plate, or the like can be used.

The coating machine for coating the slurry on the base material is not particularly limited, but for example, a roll coater, gravure coater, die coater, curtain coater, air doctor coater, etc. can be used. A die coater, a curtain coater, and a spray coater are particularly preferred because they can make the thickness of the sheet more uniform.

The slurry temperature and the ambient temperature when the slurry is applied to the substrate are not particularly limited, but are preferably 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 higher, and particularly preferably 20° C. or higher and 40° C. or lower. If the coating temperature is at least the above lower limit, the slurry can be more easily coated. When the coating temperature is equal to or lower than the above upper limit, volatilization of the dispersion medium during coating can be suppressed.

The coating step includes the step of drying the slurry applied onto the substrate, as described above. The step of drying the slurry is not particularly limited, but may be 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, but for example, a method of drying by heating with hot air, infrared rays, far infrared rays, or near infrared rays (heat drying method), or a method of drying in a vacuum (vacuum drying method) is applied. can do. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Drying with infrared rays, far-infrared rays, or near-infrared rays is not particularly limited. The heating temperature in the heat drying method is not particularly limited, but is preferably 20° C. or higher and 150° C. or lower, more preferably 25° C. or higher and 105° C. or lower. If the heating temperature is equal to or higher than the above lower limit, the dispersion medium can be rapidly volatilized. Moreover, if the heating temperature is equal to or lower than the above upper limit, it is possible to suppress the cost required for heating and suppress discoloration of fibrous cellulose due to heat.

<Papermaking process>
The papermaking process is performed by papermaking the slurry using a papermaking machine. The paper machine used in the papermaking process is not particularly limited, but examples thereof include continuous paper machines such as fourdrinier, cylinder, and inclined paper machines, and multi-layer paper machines combining these. In the paper-making process, a known paper-making method such as hand-making may be employed.

The papermaking process is carried out by filtering the slurry with a wire and dehydrating it to obtain a wet paper sheet, which is then pressed and dried. The filter cloth used for filtering and dewatering 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. Although such filter cloth is not particularly limited, for example, sheets, fabrics, and porous membranes made of organic polymers are preferable. Although the organic polymer is not particularly limited, non-cellulose organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE) are preferred. In this embodiment, for example, a polytetrafluoroethylene porous film having a pore size of 0.1 μm or more and 20 μm or less, or a polyethylene terephthalate or polyethylene fabric having a pore size of 0.1 μm or more and 20 μm or less can be used.

In the sheeting step, a method for producing a sheet from a slurry includes, for example, a squeezing section that discharges a slurry containing fibrous cellulose onto the upper surface of an endless belt and squeezes a dispersion medium out of the discharged slurry to form a web. , a drying section for drying the web to form a sheet. An endless belt is provided from the water squeezing section to the drying section, and the web produced in the water squeezing section is conveyed to the drying section while being placed on the endless belt.

A method for producing a sheet from the fine fibrous cellulose-containing slurry is not particularly limited, but includes, for example, a method using a production apparatus described in WO2011/013567. This manufacturing apparatus includes a water squeezing section that discharges a slurry containing fine fibrous cellulose onto the upper surface of an endless belt, squeezes a dispersion medium from the discharged slurry to form a web, and dries the web to form a sheet. It has a drying section for drying. An endless belt is provided from the water squeezing section to the drying section, and the web produced in the water squeezing section is conveyed to the drying section while being placed on the endless belt.

The dehydration method is not particularly limited, but includes a dehydration method commonly used in the manufacture of paper, preferably a method of dehydrating with a fourdrinier, cylinder net, inclined wire, etc., followed by dehydration with a roll press. The drying method is not particularly limited, but includes methods used in paper production, such as cylinder dryers, Yankee dryers, hot air drying, near-infrared heaters, and infrared heaters.

Examples of methods for drying the slurry to form a sheet include heat drying, blow drying, and reduced pressure drying. 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 pressure is preferably 0.01 MPa to 5 MPa. When the pressure is within the above range, the occurrence of cracks and wrinkles can be suppressed, and the density of the fiber layer can be increased.

When adding an optional component to the fiber layer, it is preferable to uniformly mix the optional component in the fiber slurry to form a fiber layer in which the optional component is dispersed. For example, if an oxygen-containing organic compound is mixed as an optional component in the fiber slurry, drying is moderated in the process of forming a sheet by drying a thin layer of the fiber slurry obtained by making paper or coating the fiber slurry. It is possible to prevent cracks and wrinkles in the fiber layer from progressing. As a result, a high-density, transparent film-like fiber layer can be formed. The dehydration method used in the papermaking process is not particularly limited, but includes, for example, dehydration methods commonly used in the manufacture of paper. Among these, the method of dehydrating with a fourdrinier, 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, but includes, for example, methods used in the manufacture of paper. Among these, a drying method using a cylinder dryer, Yankee dryer, hot air drying, near-infrared heater, infrared heater, or the like is more preferable.

(adhesion layer)
When the resin molding has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the adhesive layer preferably contains a polymer as a main component, and the polymer preferably has a glass transition temperature of less than 170°C. The glass transition temperature of the polymer contained in the adhesive layer may be calculated from literature values after identifying the type of polymer contained in the adhesive layer. may

Polymers having a glass transition temperature of less than 170° C. include polyolefins, cyclic polyolefins, polycarbonates, polyethylene terephthalate, polyethylene naphthalate, polystyrene, and acrylic polymers. Further, in order to obtain a polymer having a glass transition temperature of less than 170 ° C., when polymerizing the monomers constituting the polymer described above, any monomer may be incorporated and copolymerized to adjust the glass transition temperature of the polymer. good.

Preferably, the polymer with a glass transition temperature of less than 170°C is polycarbonate. The polymer having a glass transition temperature of less than 170°C may be a polycarbonate copolymer. In this case, monomer components used for polymerization of the polycarbonate copolymer include bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, Bisphenol P, bisphenol PH, bisphenol TMC, bisphenol Z, bisphenoxyethanolfluorene, isosorbide, 4,4-biphenol, tricyclodecanedimethanol and the like can be mentioned.

The content of the polymer having a glass transition temperature of less than 170°C is preferably 50% by mass or more, more preferably 60% by mass or more, and 70% by mass or more, relative to the total mass of the adhesive layer. is more preferable, and 80% by mass or more is particularly preferable. Also, the content of the polymer having a glass transition temperature of less than 170° C. is preferably 95% by mass or less with respect to the total mass of the adhesive layer. When the adhesive layer contains a polymer having a glass transition temperature of 170° C. or higher, the content is preferably 1% by mass or less.

The thickness of one adhesive layer is, for example, preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, and particularly preferably 2 μm or more. . The thickness of one adhesive layer is preferably 100 μm or less, more preferably 50 μm or less, still more preferably 30 μm or less, even more preferably 20 μm or less, and 10 μm or less. It is particularly preferable to have a thickness of 7 μm or less, and it is most preferable to have a thickness of 7 μm or less. When the thickness of one adhesive layer is equal to or greater than the above lower limit value, sufficient adhesion between the fiber layer and the resin layer can be obtained. Here, the thickness of the adhesive layer constituting the resin molded body is a value measured by cutting out a cross section of the resin molded body with a band saw, slide saw or laser processing machine and observing the cross section with an optical microscope or an electron microscope. is.

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

The content of the adhesion aid is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the polymer contained in the adhesive layer. Also, the content of the adhesion aid is preferably 40 parts by mass or less, more preferably 35 parts by mass or less with respect to 100 parts by mass of the polymer 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, relative to 100 parts by mass of the polymer contained in the adhesive layer. It is more preferably 18 parts by mass or more. In addition, the content of the isocyanate compound is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and preferably 30 parts by mass or less with respect to 100 parts by mass of the polymer contained in the adhesive layer. More preferred.
When the adhesion aid is an organosilicon compound, the content of the organosilicon compound is preferably 0.1 parts by mass or more, and is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the polymer contained in the adhesive layer. It is more preferable to have Also, the content of the organosilicon compound is preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the polymer contained in the adhesive layer.

When the adhesion aid is an isocyanate compound, the content of isocyanate groups contained in the adhesive layer is preferably 0.5 mmol/g or more, more preferably 0.6 mmol/g or more, and more preferably 0.8 mmol/g. /g or more, and particularly preferably 0.9 mmol/g or more. In addition, the content of isocyanate groups contained in the adhesive layer is preferably 3.0 mmol/g or less, more preferably 2.5 mmol/g or less, and further preferably 2.0 mmol/g or less. It is 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 an adhesive layer-forming composition (resin coating liquid) to the fiber 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 to apply the adhesive layer-forming composition. In addition, since such an adhesive layer is a layer that covers the surface of the fiber layer, it may be called a surface treatment layer. The adhesive layer may be a layer containing the same type of polymer as the resin layer described later. Therefore, in this specification, the resin layer directly laminated on the fiber layer is regarded as the adhesive layer, and is distinguished from the resin layer further laminated on the adhesive layer.

(resin layer)
When the resin molding has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the resin layer contains an amorphous resin. The resin layer is a layer containing an amorphous resin as a main component, and the content of the amorphous resin with respect to the total weight of the resin layer is preferably 50% by mass or more, more preferably 70% by mass or more. More preferably, it is 80% by mass or more, and particularly preferably 90% by mass or more. The content of the amorphous 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 an amorphous resin.

The thickness of the resin layer is preferably 20 μm or more, more preferably 500 μm or more, still more preferably 1.0 mm or more, even more preferably 2.0 mm or more, and 3.0 mm or more. It is particularly preferred to have Moreover, the upper limit of the thickness of the entire resin layer is not particularly limited, and may be, for example, 20 mm or less. In addition, in the case where two or more resin layers are provided in the resin molding, 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 easier to obtain a resin molding having a high elastic modulus. Here, the thickness of the resin layer constituting the resin molded body is determined by cutting out a cross section of the resin molded body with a band saw, slide saw or laser processing machine and observing the cross section with an optical microscope, an electron microscope, a magnifying glass or visually. , is the measured value.

When the resin molding has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the fiber layer functions as a reinforcing layer for the resin layer, so the resin layer should be thicker than the fiber layer. is preferred. When P is the total thickness of the resin layers and Q is the total thickness of the fiber layers, the value of P/Q is preferably 1.2 or more, more preferably 1.5 or more. It is more preferably 2.0 or more. The value of P/Q is preferably 80 or less. Further, when the total thickness of the resin layers is P and the thickness of the adhesive layer is R, the value of P/R is preferably 20 or more, more preferably 50 or more, and 80 or more. is more preferred. The value of P/R is preferably 10000 or less.

Examples of the amorphous resin contained in the resin layer include polycarbonate, polyvinyl chloride, polystyrene, polymethylmethacrylate, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyetherimide, and polyamideimide. can. Among them, the amorphous resin is preferably a polycarbonate, more preferably a polycarbonate obtained by homopolymerization. Also, the amorphous 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 resin molding tends to increase and the coefficient of linear thermal expansion tends to decrease.

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

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

The resin layer provided as the outermost layer may be a layer formed from a resin film. In this case, it is preferable that the resin film also contains the amorphous resin described above. Moreover, the resin film may contain the arbitrary component mentioned above.

The thickness of the resin film forming the resin layer is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. Also, the thickness of the resin film is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 300 μm or less.

(arbitrary layer)
The resin molding may further contain arbitrary layers in addition to the layers described above. Examples of optional layers include an inorganic layer, a hard coat layer, an antifogging layer, an antiglare layer, and the like.

<Inorganic layer>
The resin molding may further have an inorganic layer. The inorganic layer may be provided as the outermost layer of the resin molded body, or may be provided as a layer constituting the inner side of the resin molded body.

The material constituting the inorganic layer is not particularly limited, but for example, aluminum, silicon, magnesium, zinc, tin, nickel, titanium; or mixtures thereof. From the viewpoint of stably maintaining high moisture resistance, silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxycarbide, aluminum oxynitride, or these Mixtures are preferred.

A method for forming the inorganic layer is not particularly limited. In general, methods for forming thin films are roughly classified into chemical vapor deposition (CVD) and physical vapor deposition (PVD), and either 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 thermally decomposed using a heated catalyst, and the like. Specific examples of the PVD method include vacuum deposition, ion plating, and sputtering.

Moreover, as a method for forming the inorganic layer, an atomic layer deposition (ALD) method can be employed. The ALD method is a method of forming a thin film in units of atomic layers by alternately supplying raw material gases of elements constituting a film to be formed to a surface on which a layer is to be formed. Although it has the disadvantage of a slow deposition rate, it has the advantage over the plasma CVD method that even surfaces with complicated shapes can be covered cleanly, and a thin film with few defects can be deposited. In addition, the ALD method has the advantage that the film thickness can be controlled on the order of nanometers, and that it is relatively easy to cover a wide surface. Furthermore, the ALD method is expected to improve the reaction rate, lower the temperature of the process, and reduce unreacted gas by using plasma.

Although the thickness of the inorganic layer is not particularly limited, for example, when aiming to exhibit moisture resistance, it is preferably 5 nm or more, more preferably 10 nm or more, and even more 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 even more preferably 600 nm or less.

(Manufacturing method of resin molding)
The resin molding of the present invention may have a single-layer structure in which resin and fine fibrous cellulose are mixed. A method for producing a single-layered resin molding obtained by mixing a resin and fine fibrous cellulose may include a step of mixing the resin and fine fibrous cellulose to obtain a resin composition, and a step of molding the resin composition. preferable.

The step of mixing the resin and the fine fibrous cellulose to obtain the resin composition may be the step of mixing the resin solution and the fine fibrous cellulose dispersion, or the step of melt-kneading the molten resin and the fine fibrous cellulose. is preferably In the step of mixing the resin and the fine fibrous cellulose, the fine fibrous cellulose may be in a solid state or in a dispersion state dispersed in a dispersion medium. In this case, the dispersion medium is not particularly limited, but preferably contains water, more preferably a solvent containing water as a main component. Examples of organic solvents include dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), aniline, pyridine, quinoline, lutidine, acetonitrile, tetrahydrofuran (THF), dimethylsulfoxide (DMSO), Dioxane, ethanol, isopropanol and the like can be mentioned. A mixed solvent obtained by mixing these organic solvents and water can also be used as the dispersion medium.

In the step of mixing the resin and the fine fibrous cellulose, when the fine fibrous cellulose dispersion and the resin are mixed, the concentration of the fine fibrous cellulose dispersion is preferably 0.1% by mass or more, and is preferably 1.0% by mass or more. It is more preferably at least 2.0% by mass, and even more preferably at least 2.0% by mass. Also, the concentration of the fine fibrous cellulose dispersion may be 3.0% by mass or more.

When the step of mixing the resin and the fine fibrous cellulose is a step of mixing the resin and the solid fine fibrous cellulose, the solid fine fibrous cellulose can be obtained, for example, by concentrating the fine fibrous cellulose dispersion. is obtained by In this case, the concentration step includes a method of evaporating the dispersion medium, a concentration method using a flocculating agent, a spray drying method, a freeze drying method, a vacuum drying method, a replacement method with an inert gas such as nitrogen or argon, and the like. can be done.

The water content in the solid fine fibrous cellulose is preferably 25% by mass or less, more preferably 20% by mass or less, and 15% by mass or less with respect to the total mass of the solid. It is even more preferable to have By setting the water content in the solid fine fibrous cellulose within the above range, the fine fibrous cellulose is easily dispersed uniformly in the resin.

The step of mixing the resin and the fine fibrous cellulose is preferably a melt-kneading step. In the melt-kneading step, for example, a single (single) screw extruder kneader, a multi-screw extruder kneader with two or more screws, a kneader, a roll mill, a Banbury mixer, a screw press, or the like can be used.

In the melt-kneading step, the cylinder temperature of the kneader is preferably the melting point of the resin or higher and the melting point +120° C. or lower, more preferably the melting point or higher and the melting point +60° C. or lower. For example, the cylinder temperature is preferably 80° C. or higher and 400° C. or lower, more preferably 125° C. or higher and 280° C. or lower. Also, the nozzle temperature in the kneader is preferably 75° C. or higher and 395° C. or lower, more preferably 120° C. or higher and 275° C. or lower.

In the melt-kneading step, when a twin-screw extruder kneader is used, the rotation speed of the twin-screws is preferably 100 rpm or more and 500 rpm or less, more preferably 250 rpm or more and 350 rpm or less.

The step of molding the resin molded article of the present invention from the resin composition described above may be, for example, a step of heat-molding the resin composition by vacuum molding or the like, or a heat-pressure molding of the resin composition. can be anything. Moreover, the resin molding may be formed by compression molding, injection molding, inflation molding, or extrusion molding of the resin composition. The molding conditions are appropriately adjusted depending on the type of resin contained in the resin molded body.

When the resin molded body has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the method for producing the resin molded body includes a fiber layer containing fibrous cellulose with a fiber width of 1000 nm or less, an adhesive layer and a resin layer. It is preferable to include a step of hot pressing after laminating in this order. Here, it is preferable that the resin layer contains an amorphous resin, the adhesive layer contains a polymer, and the polymer has a glass transition temperature of less than 170°C. In this case, the method for producing a resin molding includes a step of laminating a fibrous layer containing fibrous cellulose with a fiber width of 1000 nm or less, an adhesive layer and a resin layer in this order, followed by hot pressing. Here, the heating temperature in the hot pressing step is preferably less than 170°C. The heating temperature in the hot pressing step is preferably 100° C. or higher.

The pressure in the hot press step is preferably 0.1 MPa or higher, more preferably 0.5 MPa or higher, even more preferably 1 MPa or higher, and particularly preferably 5 MPa or higher. Moreover, the pressure in the hot pressing step is preferably 100 MPa or less, more preferably 50 MPa or less, and even more preferably 20 MPa or less.

It is preferable to provide a step of forming an adhesive layer on the fiber layer before the step of hot pressing. In the step of forming an adhesive layer on the fiber layer, a resin coating solution for forming an adhesive layer is applied onto the fiber layer (fine fibrous cellulose-containing sheet) formed by the method described above to form an adhesive layer. is preferred. In addition, in the step of forming an adhesive layer on the fiber layer, a previously formed adhesive layer may be laminated on the fiber layer (fine fibrous cellulose-containing sheet) formed by the method described above.

When the resin molded body has a laminated structure having a fiber layer, an adhesive layer, and a resin layer in this order, in the method for manufacturing the resin molded body, for example, after forming adhesive layers on both sides of the fiber layer, on each adhesive layer After laminating the resin layers to form a structure of resin layer/adhesive layer/fiber layer/adhesive layer/resin layer, a step of hot pressing may be provided. In this case, the area of the resin layer may be the same as that of the fiber layer, or the area of the resin layer may be larger than that of the fiber layer. For example, in the structure of resin layer/adhesive layer/fiber layer/adhesive layer/resin layer, by making the area of the two resin layers arranged as the outermost layers larger than the area of the fiber layer, It is also possible to join the two resin layers arranged as the outermost layer to each other at the ends. As a result, the fiber layer is covered with the amorphous resin in the resin molding. In addition, in the hot press step, a resin film may be used instead of the resin layer. As the resin constituting the resin film, the same resin as the resin constituting the resin layer described above can be used.

As described above, when the resin molded body has a laminated structure having a fiber layer, an adhesive layer and a resin layer in this order, the method for manufacturing the resin molded body preferably includes a hot press step. In the resin molded product obtained through the hot press process, it is easy to achieve a high elastic modulus (flexural modulus) and a low linear thermal expansion coefficient, and the resin molded product has both excellent design and durability. can.

(Application)
Since the resin molding constituting the double-layered resin glass is transparent and excellent in mechanical strength and dimensional stability, the double-layered resin glass of the present invention is also transparent and excellent in mechanical strength and dimensional stability. In addition, since the double-layered resin glass of the present invention has hollow layers (spaces) between the resin moldings, it can exhibit excellent performance in terms of sound insulation as well. Therefore, the double-layered resin glass of the present invention is preferably used for members of various household appliances, window materials for various vehicles and buildings, interior materials, exterior materials, solar cell members, and the like.

The present invention may also relate to an automotive window unit having double-layer resin glass.

EXAMPLES The characteristics of the present invention will be described more specifically below with reference to examples and comparative examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

<Production Example 1>
[Phosphorylation treatment]
As raw material pulp, hardwood dissolving pulp (dry sheet) manufactured by Oji Paper Co., Ltd. was used. The raw material pulp was subjected to a phosphorylation 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. A chemical-impregnated pulp was obtained by adjusting as follows. Next, the resulting chemical solution-impregnated pulp was heated in a hot air dryer at 165° C. for 250 seconds to introduce phosphoric acid groups into cellulose in the pulp to obtain phosphorylated pulp.

[Washing process]
Then, the obtained phosphorylated pulp was washed. In the washing treatment, a pulp dispersion liquid obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp is stirred so that the pulp is uniformly dispersed, and then filtration and dehydration are repeated. gone. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

[Neutralization treatment]
Next, the washed phosphorylated pulp was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N sodium hydroxide aqueous solution was added little by little while 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 neutralized phosphorylated pulp. Next, the washing treatment was performed on the phosphorylated pulp after the neutralization treatment.

The phosphorus oxo-oxidized pulp thus obtained was subjected to infrared absorption spectrum measurement using FT-IR. As a result, an absorption based on P=O of the phosphate group was observed near 1230 cm ^-1 , confirming that the phosphate group was added to the pulp. In addition, when the obtained phosphorylated pulp was tested and analyzed with an X-ray diffraction device, it was found that the A typical peak was confirmed, confirming that it had cellulose type I crystals.

[Fibrillation 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 six times with a wet atomization device (Starburst, manufactured by Sugino Machine Co., Ltd.) at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. When the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 2 to 5 nm. It was confirmed by X-ray diffraction that the resulting fine fibrous cellulose maintained cellulose type I crystals. The amount of phosphate groups (first dissociated acid amount) measured by the measurement method described in Measurement of [Amount of Phosphorus Acid Groups] described later was 1.45 mmol/g. The total amount of dissociated acid was 2.45 mmol/g.

<Production Example 2>
[TEMPO oxidation treatment]
Softwood kraft pulp (undried) manufactured by Oji Paper Co., Ltd. was used as raw material pulp. The raw material pulp was subjected to alkali TEMPO oxidation treatment as follows. First, the raw pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), 10 parts by mass of sodium bromide, and 10000 parts by mass of water distributed in parts. Then, a 13% by mass sodium hypochlorite aqueous solution was added to 3.8 mmol with respect to 1.0 g of pulp to initiate the reaction. During the reaction, a 0.5 M sodium hydroxide aqueous solution was added dropwise to maintain the pH at 10 or more and 10.5 or less, and the reaction was considered completed when no change in pH was observed.

Then, the obtained TEMPO oxidized pulp was washed. The washing treatment is performed by dehydrating the pulp slurry after TEMPO oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring to uniformly disperse, and then filtering and dehydrating repeatedly. rice field. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

This dehydrated sheet was subjected to a post-oxidation treatment for residual aldehyde groups as follows. The dehydrated sheet equivalent to 100 parts by mass of dry mass was dispersed in 10000 parts by mass of 0.1 mol/L acetate buffer (pH 4.8). Next, 113 parts by mass of 80% by mass sodium chlorite was added, and the mixture was immediately sealed, followed by reaction at room temperature for 48 hours while stirring at 500 rpm using a magnetic stirrer to obtain a pulp slurry.

Then, the obtained after-oxidized TEMPO oxidized pulp was washed. The washing treatment is carried out by dehydrating the post-oxidized pulp slurry to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring to uniformly disperse, and then filtering and dehydrating repeatedly. rice field. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less. Then, ion-exchanged water was added to the obtained TEMPO oxidized pulp to obtain a dispersion having a concentration of 0.5% by mass, thereby completing the neutralization treatment of the cellulose fibers.

When the obtained TEMPO oxidized pulp was tested and analyzed with an X-ray diffraction device, it was found to be typical at two positions near 2θ = 14° or more and 17° or less and 2θ = 22° or more and 23° or less. A peak was confirmed, and it was confirmed to have cellulose type I crystals. Moreover, it was confirmed by X-ray diffraction that the obtained fibrous cellulose maintained cellulose type I crystals.

A fine fibrous cellulose dispersion containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the above-mentioned TEMPO oxidized pulp was used in [defibration treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals. The carboxy group content measured by the method described in [Measurement of carboxy group content] described later was 1.80 mmol/g.

<Production Example 3>
[Phosphorous oxidation treatment]
The procedure was carried out in the same manner as in Production Example 1, except that 33 parts by mass of phosphorous acid (phosphonic acid) was used instead of ammonium dihydrogen phosphate in [Phosphorylation treatment] of Production Example 1, and phosphorous oxidized pulp and fine A fine fibrous cellulose dispersion containing fibrous cellulose was obtained.

An infrared absorption spectrum was measured for the obtained phosphorous oxidized pulp using FT-IR. As a result, an absorption based on P=O of a phosphonic acid group, which is a tautomer of a phosphite group, was observed near 1210 cm ⁻¹ , indicating that a phosphite group (phosphonic acid group) was added to the pulp. was confirmed. When the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 2 to 5 nm. Moreover, it was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained cellulose type I crystals. The amount of phosphite groups (first dissociated acid amount) measured by the measuring method described later in [Measurement of Phosphorus Acid Group Amount] was 1.51 mmol/g, and the total dissociated acid amount was 1.51 mmol/g. It was 54 mmol/g.

<Production Example 4>
After the washing treatment and neutralization treatment of the phosphorylated pulp of Production Example 1, the following treatments were performed to obtain a substituent-removed fine fibrous cellulose dispersion liquid containing substituent-removed fine fibrous cellulose.

[Nitrogen removal treatment]
Ion-exchanged water was added to the phosphorylated pulp to prepare a slurry having a solid content concentration of 4% by mass. A 48% by mass sodium hydroxide aqueous solution was added to the slurry to adjust the pH to 13.4, and the slurry was heated for 1 hour under conditions where the liquid temperature was 85°C. After that, the pulp slurry is dehydrated, and the pulp dispersion obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry weight) of phosphorylated pulp is stirred so that the pulp is uniformly dispersed, followed by filtration and dehydration. was repeated to remove excess sodium hydroxide. The removal was terminated when the electric conductivity of the filtrate became 100 μS/cm or less.

The phosphorus oxyoxidized pulp thus obtained was subjected to infrared absorption spectrum measurement using FT-IR. As a result, an absorption based on P=O of the phosphate group was observed near 1230 cm ^-1 , confirming that the phosphate group was added to the pulp.

[Fibrillation 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 six times with a wet atomization device (Starburst, manufactured by Sugino Machine Co., Ltd.) at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion containing fine fibrous cellulose. When the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals. The phosphate group content (first dissociated acid content) measured by the measurement method described in the measurement of [phosphoric acid group content] described later was 1.35 mmol/g. The total amount of dissociated acid was 2.30 mmol/g.

[Substituent removal treatment (high temperature heat treatment)]
A 20 mass % citric acid aqueous solution was added to the fine fibrous cellulose dispersion to adjust the pH of the dispersion to 5.5. The resulting slurry was placed in a pressure vessel and heated at a liquid temperature of 160° C. for 15 minutes. At this time, the heating was continued until the amount of phosphate groups reached 0.08 mmol/g. It was confirmed that this operation produced aggregates of fine fibrous cellulose.

[Washing treatment of slurry after removal of substituents]
To the slurry after heating, the same amount of ion-exchanged water as the slurry was added to prepare a slurry having a solid content concentration of about 1% by mass. After stirring the slurry, the slurry was washed by repeating the operation of filtering and dewatering. When the electric conductivity of the filtrate became 10 μS/cm or less, ion-exchanged water was added again to obtain a slurry of about 1% by mass, and the slurry was allowed to stand for 24 hours. From there, the operation of filtering and dehydrating was repeated, and the washing was finished when the electrical conductivity of the filtrate became 10 μS/cm or less. Ion-exchanged water was added to the obtained aggregate of fine fibrous cellulose to obtain a slurry after removal of substituents. The solid content concentration of this slurry was 1.7% by mass.

[Uniform dispersion of slurry after removal of substituents]
Ion-exchanged water was added to the obtained slurry after removing the substituents to obtain a slurry having a solid content concentration of 1.0% by mass, and then a wet atomization apparatus (Starburst manufactured by Sugino Machine Co., Ltd.) was used at a pressure of 200 MPa. After three treatments, a dispersion of substituent-removed fine fibrous cellulose containing substituent-removed fine fibrous cellulose was obtained. The number average fiber width of the substituent-removed fine fibrous cellulose measured in [Measurement of Fiber Width] described later was 4 nm.

<Production Example 5>
[Sulfation treatment]
In the phosphorylation treatment, 38 parts by mass of amidosulfuric acid (sulfamic acid) was used instead of ammonium dihydrogen phosphate, and the heating time was extended to 19 minutes. A fine fibrous cellulose dispersion containing fine fibrous cellulose was obtained.

The sulfated pulp thus obtained was subjected to infrared absorption spectrum measurement using FT-IR. As a result, absorption due to S=O of the sulfate group was observed near 1220-1260 cm ^-1 , confirming that the sulfate group was added to the pulp. Moreover, it was confirmed by X-ray diffraction that the obtained fine fibrous cellulose maintained cellulose type I crystals. The amount of sulfur oxoacid groups measured by the method described in [Measurement of sulfur oxoacid groups] described later was 1.12 mmol/g.

<Production Example 6>
[Hypochlorous acid oxidation]
A sheet of softwood bleached kraft pulp (NBKP) (solid content concentration 90% by mass) is processed with a hand mixer (Labo Milcer PLUS, manufactured by Osaka Chemical Co., Ltd.) at a rotation speed of 20000 rpm for 15 seconds to form a flocculent. Fluffing pulp (solid content concentration 90% by mass) was prepared. Next, sodium hypochlorite pentahydrate was added to the ion-exchanged water to prepare an aqueous solution having a sodium hypochlorite solid content concentration of 22% by mass. 9000 parts by mass of a 22% by mass sodium hypochlorite aqueous solution was added to 100 parts by mass of cotton-like fluffing pulp, and the mixture was reacted for 2 hours while adjusting the temperature to 30°C in a hot bath to obtain a carboxy group-introduced pulp. The pH was maintained at 11 by appropriately adding 1N sodium hydroxide aqueous solution during the reaction.

Next, the obtained carboxy group-introduced pulp was washed. The washing treatment was carried out by repeating an operation of filtering and dehydrating a pulp dispersion liquid obtained by pouring ion-exchanged water into the obtained carboxy group-introduced pulp, stirring the pulp so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

The carboxy group content of the resulting carboxy group-introduced pulp measured by the measurement method described later was 0.70 mmol/g. In addition, when the obtained carboxyl group-introduced pulp was tested and analyzed with an X-ray diffraction device, two positions near 2θ = 14° or more and 17° or less and 2θ = 22° or more and 23° or less were found. A typical peak was confirmed in , and it was confirmed to have cellulose type I crystals.

A fine fibrous cellulose dispersion liquid containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the carboxy group-introduced pulp described above was used in the [defibration treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals.

<Production Example 7>
[Maleic acid esterification]
A sheet of softwood bleached kraft pulp (NBKP) (solid content concentration 90% by mass) is processed with a hand mixer (Labo Milcer PLUS, manufactured by Osaka Chemical Co., Ltd.) at a rotation speed of 20000 rpm for 15 seconds to form a flocculent. Fluffing pulp (solid content concentration 90% by mass) was prepared. An autoclave was charged with 100 parts by mass of cotton-like fluffing pulp and 50 parts by mass of maleic anhydride and treated at 150° C. for 2 hours to obtain a carboxy group-introduced pulp.

Next, the obtained carboxy group-introduced pulp was washed. The washing treatment was carried out by repeating an operation of filtering and dehydrating a pulp dispersion liquid obtained by pouring ion-exchanged water into the obtained carboxy group-introduced pulp, stirring the pulp so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

An infrared absorption spectrum was measured for the resulting carboxy group-introduced pulp using FT-IR. As a result, absorption due to carboxy groups was observed near 1580 and 1720 cm ⁻¹ , confirming maleic acid esterification. The carboxy group content of the resulting carboxy group-introduced pulp measured by the measurement method described later was 1.22 mmol/g. In addition, when the carboxy group-introduced pulp was tested and analyzed with an X-ray diffraction device, typical A peak was confirmed, and it was confirmed to have cellulose type I crystals.

A fine fibrous cellulose dispersion liquid containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the carboxy group-introduced pulp described above was used in the [defibration treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals.

<Production Example 8>
[Carboxyethylation]
As raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 245 g / m ² sheet, disaggregated and measured according to JIS P 8121-2: 2012 Canadian standard freeness (CSF ) used 700 ml).

To 100 parts by mass (absolute dry mass) of this raw pulp, a chemical solution consisting of 250 parts by mass of 12N NaOH aqueous solution, 163 parts by mass of 2-chloropropionic acid, and 140 parts by mass of ion-exchanged water (total 553 parts by mass) was added. An impregnated pulp was obtained. Next, the resulting chemical solution-impregnated pulp was heated in a hot air dryer at 165° C. for 10 minutes to introduce carboxyethyl groups (carboxy groups) into the cellulose in the pulp to obtain carboxy group-introduced pulp.

Next, the obtained carboxy group-introduced pulp was washed. The washing treatment was carried out by repeating an operation of filtering and dehydrating a pulp dispersion liquid obtained by pouring ion-exchanged water into the obtained carboxy group-introduced pulp, stirring the pulp so that the pulp is uniformly dispersed, and then filtering and dehydrating the pulp. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

Next, the washed carboxy group-introduced pulp was neutralized as follows. First, after diluting the washed carboxy group-introduced pulp with 10 L of deionized water, a 1 N sodium hydroxide aqueous solution was added little by little while stirring to prepare a carboxy group-introduced pulp slurry having a pH of 12 or more and 13 or less. Obtained. Next, the carboxyl group-introduced pulp slurry was dewatered and washed to obtain neutralized carboxyl group-introduced pulp. Then, ion-exchanged water was added to the resulting carboxy group-introduced pulp to prepare a 0.5% by mass concentration dispersion, thereby completing the neutralization treatment of the cellulose fibers.

The carboxy group content of the resulting carboxy group-introduced pulp measured by the measurement method described later was 1.41 mmol/g. In addition, when the carboxy group-introduced pulp was tested and analyzed with an X-ray diffraction device, typical A peak was confirmed, and it was confirmed to have cellulose type I crystals.

A fine fibrous cellulose dispersion liquid containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the carboxy group-introduced pulp described above was used in the [defibration treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals.

<Production Example 9>
[Sulfoethylation]
As raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 245 g / m ² sheet, disaggregated and Canadian standard freeness measured according to JIS P 8121-2: 2012 (CSF) of 700 ml) was used.

To 100 parts by mass (absolute dry mass) of this raw material pulp, a chemical solution consisting of 180 parts by mass of a 2N NaOH aqueous solution and 780 parts by mass of a 25% by mass sodium vinylsulfonate aqueous solution (960 parts by mass in total) was added to obtain a chemical solution-impregnated pulp. Obtained. Next, the resulting chemical solution-impregnated pulp was heated in a hot air dryer at 165° C. for 16 minutes to introduce sulfoethyl groups (sulfone groups) into the cellulose in the pulp to obtain sulfoethyl group-introduced pulp (sulfone group-introduced pulp).

Next, the resulting sulfoethyl group-introduced pulp was washed. The washing treatment was carried out by repeating an operation of filtering and dehydrating a pulp dispersion liquid obtained by pouring ion-exchanged water into the resulting sulfoethyl group-introduced pulp, stirring the pulp to uniformly disperse the pulp, and then filtering and dehydrating the pulp. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

The sulfoethyl group content (sulfone group content) of the resulting sulfoethyl group-introduced pulp measured by the method described later was 1.48 mmol/g. In addition, when the sulfoethyl group-introduced pulp was tested and analyzed with an X-ray diffractometer, typical A peak was confirmed, and it was confirmed to have cellulose type I crystals.

A fine fibrous cellulose dispersion liquid containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the carboxy group-introduced pulp described above was used in the [defibration treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals.

<Production Example 10>
[Cationization treatment]
As raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 245 g / m ² sheet, disaggregated and Canadian standard freeness measured according to JIS P 8121-2: 2012 (CSF) of 700 ml) was used.

To 100 parts by mass (absolute dry mass) of this raw material pulp, 180 parts by mass of 1N NaOH aqueous solution and a cationizing agent (Catiomaster G, manufactured by Yokkaichi Gosei Co., Ltd., glycidyltrimethylammonium chloride, pure content 73.1% by mass, moisture content 20.2% by mass) 325 parts by mass of the chemical solution (505 parts by mass in total) was added to obtain a chemical solution-impregnated pulp. Next, the resulting chemical solution-impregnated pulp was heated in a hot air dryer at 165° C. for 12 minutes to introduce cationic groups into the cellulose in the pulp to obtain cationic group-introduced pulp.

Next, the resulting cationic group-introduced pulp was washed. The washing treatment was carried out by repeating an operation of filtering and dehydrating a pulp dispersion obtained by pouring ion-exchanged water into the obtained cationic group-introduced pulp, stirring the pulp so that the pulp is uniformly dispersed, and then filtering and dehydrating. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.

Next, the cationic group-introduced pulp after washing was neutralized as follows. First, the cationic group-introduced pulp after washing is diluted with 10 L of ion-exchanged water, and then 1N hydrochloric acid is added little by little while stirring to obtain a cationic group-introduced pulp slurry having a pH of 1 or more and 2 or less. rice field. Next, the cationic group-introduced pulp slurry was dehydrated and washed to obtain neutralized cationic group-introduced pulp. Then, ion-exchanged water was added to the resulting cationic group-introduced pulp to prepare a dispersion having a concentration of 0.5% by mass, thereby completing the neutralization treatment of the cellulose fibers.

The resulting cationic group-introduced pulp was subjected to trace nitrogen analysis, and the amount of cationic groups was calculated according to the following formula and found to be 1.45 mmol/g. In addition, when a cationic group-introduced pulp was tested and analyzed with an X-ray diffraction device, typical A specific peak was confirmed, and it was confirmed to have cellulose type I crystals.
(Amount of cationic group) [mmol/g]=(Amount of nitrogen)/14×1000/(Amount of cationic group-introduced pulp tested)

A fine fibrous cellulose dispersion liquid containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the carboxy group-introduced pulp described above was used in the [defibration treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals.

<Production Example 11>
A fine fibrous cellulose dispersion containing xanthate pulp and fine fibrous cellulose was obtained in the same manner as in Production Example 1 except that the following xanthate treatment was performed instead of the phosphorylation treatment.

[Xanthate treatment]
2500 parts by mass of 8.5% by mass sodium hydroxide aqueous solution is added to 100 parts by mass (absolute dry mass) of raw material pulp (hardwood dissolving pulp (dry sheet) manufactured by Oji Paper Co., Ltd.) and stirred at room temperature for 3 hours. Then, alkali treatment was performed. The alkali-treated pulp was subjected to solid-liquid separation by centrifugation (filter cloth 400 mesh, 3000 rpm for 5 minutes) to obtain dehydrated alkali cellulose. 3.5 parts by mass of carbon disulfide is added to 10 parts by mass (absolute dry mass) of the obtained alkali cellulose, and a sulfurization reaction is allowed to proceed at room temperature for 4.5 hours to perform a xanthate treatment to introduce xanthate groups. A pulp was obtained.

A fine fibrous cellulose dispersion liquid containing fine fibrous cellulose was obtained in the same manner as in Production Example 1, except that the above-described xanthate group-introduced pulp was used in [Fibrillation treatment] of Production Example 1. When the fiber width of the fine fibrous cellulose in the fine fibrous cellulose dispersion was measured using a transmission electron microscope, it was 2 to 5 nm. It was confirmed by X-ray diffraction that the resulting fine fibrous cellulose maintained cellulose type I crystals. The xanthate group content measured by the measuring method described in [Measurement of xanthate group content] described later was 1.73 mmol/g.

[Substituent elimination (low temperature heat treatment)]
The obtained fine fibrous cellulose dispersion liquid was heated at a liquid temperature of 40° C. for 45 minutes to 1 hour until the xanthate group amount became less than 0.081 mmol/g.

Except for using the fine fibrous cellulose dispersion after the removal of substituents, the [washing treatment of slurry after removal of substituents] and [uniform dispersion of slurry after removal of substituents] of Production Example 4 were carried out, and fine fibers were obtained. A fine cellulose dispersion was obtained.

<Example 1>
[Production of sheet (fiber layer)]
Acetoacetyl group-modified polyvinyl alcohol (manufactured by Mitsubishi Chemical Corporation, Gohsenex Z-200) was added to ion-exchanged water so as to make 12% by mass, and dissolved by stirring at 95° C. for 1 hour. A polyvinyl alcohol aqueous solution was obtained by the above procedure.

The fine fibrous cellulose dispersion obtained in Production Example 1 and the polyvinyl alcohol aqueous solution were each diluted with ion-exchanged water so that the solid content concentration was 1.0% by mass. Next, 30 parts by mass of the diluted polyvinyl alcohol aqueous solution was mixed with 70 parts by mass of the diluted fine fibrous cellulose dispersion to obtain a mixed liquid. Further, the mixed solution was measured so that the finished basis weight of the sheet was 225 g/m ² and spread on a commercially available acrylic plate. A damming frame (inner dimensions: 250 mm×250 mm, height: 5 cm) was arranged on the acrylic plate so as to obtain a predetermined basis weight. After that, it was dried in a drier at 70° C. for 48 hours and separated from the acrylic plate to obtain a sheet containing fine fibrous cellulose. The thickness of the sheet was 150 µm.

[Formation of adhesive layer]
Based on Iupizeta FPC-2136 manufactured by Mitsubishi Gas Chemical Co., Ltd., 8.5 parts by mass of polycarbonate resin, which is a copolymer of multiple monomers adjusted to have a glass transition temperature of 130 ° C., 60 parts by mass of toluene, 30 parts by mass of methyl ethyl ketone was mixed. Next, 1.5 parts by mass of an isocyanate compound (manufactured by Asahi Kasei Chemicals Co., Ltd., Duranate TPA-100) as an adhesion aid was added and mixed to obtain a resin coating liquid. This resin coating liquid was applied to one surface (the surface in contact with the acrylic plate) of the fine fibrous cellulose-containing sheet using a bar coater. Thereafter, the resin coating liquid was cured by heating at 100° C. for 1 hour to form an adhesive layer (first adhesive layer). Next, an adhesive layer (second adhesive layer) was formed on the opposite side of the fine fibrous cellulose-containing sheet by the same procedure. The thickness of the adhesive layer was 3 μm per side. By the above procedure, an adhesive layer-laminated sheet was obtained in which adhesive layers were laminated on both sides of the fine fibrous cellulose-containing sheet.

[Formation of amorphous resin layer]
Two 150 mm square adhesive layer laminated sheets were cut out, and one polycarbonate plate with dimensions of 170 mm square and thickness of 2 mm and two polycarbonate films with dimensions of 170 mm square and thickness of 300 μm were cut into polycarbonate film/adhesive layer laminated sheet/polycarbonate plate. /adhesive layer laminate sheet/polycarbonate film were stacked in the order of the center. Furthermore, these were sandwiched between two stainless steel plates each having a size of 200 mm square. After that, it was inserted into a mini test press (manufactured by Toyo Seiki Kogyo Co., Ltd., MP-WCH) set at room temperature and heated to 160° C. over 3 minutes under a press pressure of 12 MPa. After maintaining this state for 0.5 minutes, it was cooled to 30° C. over 1.5 minutes. Through the above procedure, a resin molding having a laminated structure containing a sheet containing fine fibrous cellulose, an adhesive layer, and an amorphous resin was obtained. In this resin molding, the ends of the fine fibrous cellulose-containing sheet were covered with an amorphous resin.

The layer structure of the resin molding obtained in Example 1 is the same as that shown in FIG. The cross section is a plane that passes through the center point of the resin molded body, and is a plane that appears when cut in the thickness direction. In addition, since FIG. 9 illustrates the layer structure for easy understanding, the thickness of each layer and the thickness ratio are not necessarily the same as those of the actual resin molding. In FIG. 9, 40 denotes a resin film (polycarbonate film).

[Formation of module for sound insulation test]
Two circular test pieces with a diameter of 47.5 mm were cut out from the resin molding. These two test pieces were set so that the gap between the test pieces was 1 mm, and set in a test piece fixing jig of a cylindrical vertical incident sound absorption coefficient measurement system (WinZac MTX manufactured by Nippon Onkyo Engineering Co., Ltd.). A module for a sound insulation test was made imitating a multi-layered resin glass in which a space (hollow layer) was formed between the resin moldings. This sound insulation test evaluation module was subjected to a sound insulation test described later.

<Example 2>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 2 was used. were obtained respectively.

<Example 3>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 3 was used. were obtained respectively.

<Example 4>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 4 was used. were obtained respectively.

<Example 5>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 5 was used. were obtained respectively.

<Example 6>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 6 was used. were obtained respectively.

<Example 7>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 7 was used. were obtained respectively.

<Example 8>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 8 was used. were obtained respectively.

<Example 9>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that the fine fibrous cellulose obtained in Production Example 9 was used. were obtained respectively.

<Example 10>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1, except that the fine fibrous cellulose obtained in Production Example 10 was used. were obtained respectively.

<Example 11>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 1, except that the fine fibrous cellulose obtained in Production Example 10 was used. were obtained respectively.

<Example 12>
A fine fibrous cellulose dispersion was obtained in the same manner as in Example 1 except that 40 parts by mass of the diluted fine fibrous cellulose dispersion was mixed with 60 parts by mass of the diluted polyvinyl alcohol aqueous solution to obtain a mixed solution. A cellulose-containing sheet, a resin molded body, and a module for sound insulation test imitating double-layered resin glass having two resin molded bodies and a hollow layer were obtained, respectively.

<Example 13>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin having two resin moldings and a hollow layer were prepared in the same manner as in Example 12, except that the fine fibrous cellulose obtained in Production Example 4 was used. A sound insulation test module imitating glass was obtained.

<Example 14>
Methyl cellulose (manufactured by Shin-Etsu Chemical Co., Ltd., Metolose 65SH-1500, weight average molecular weight: 2.2 × 10 ⁵ , degree of substitution (methoxy group): 1.8, number of moles of substitution (hydroxypropoxy group): 0.15) was added so as to be 2% by mass, and the solution was dissolved by stirring at room temperature for 1 hour. A cellulose ether aqueous solution was obtained by the above procedure.
Ion-exchanged water was added to the cellulose ether aqueous solution obtained by the above procedure to dilute the solid content concentration to 1.0% by mass. A fine fibrous cellulose-containing sheet, a resin molding, two resin moldings and a hollow layer were prepared in the same manner as in Example 1 except that this diluted cellulose ether aqueous solution was used instead of the diluted polyvinyl alcohol aqueous solution. A soundproofing test module imitating the multi-layered resin glass was obtained.

<Example 15>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 14 except that the fine fibrous cellulose obtained in Production Example 4 was used. were obtained respectively.

<Example 16>
A fine fibrous cellulose dispersion was prepared in the same manner as in Example 1, except that 60 parts by mass of the diluted cellulose ether aqueous solution was mixed with 40 parts by mass of the diluted fine fibrous cellulose dispersion to obtain a mixed solution. A cellulose-containing sheet, a resin molded body, and a module for sound insulation test imitating double-layered resin glass having two resin molded bodies and a hollow layer were obtained, respectively.

<Example 17>
A sheet containing fine fibrous cellulose, a resin molded body, and a multilayer resin glass having two resin molded bodies and a hollow layer were prepared in the same manner as in Example 16 except that the fine fibrous cellulose obtained in Production Example 4 was used. were obtained respectively.

<Example 18>
A fine fibrous cellulose-containing sheet, a resin molded article, and two resin molded articles were prepared in the same manner as in Example 1, except that a 2 mm thick polymethyl methacrylate (PMMA) plate was used instead of the 2 mm thick polycarbonate plate. and a module for sound insulation test imitating multi-layered resin glass having a hollow layer.

<Example 19>
A sheet containing fine fibrous cellulose, a resin molding, and a multilayer resin glass having two resin moldings and a hollow layer were prepared in the same manner as in Example 18, except that the fine fibrous cellulose obtained in Production Example 4 was used. were obtained respectively.

<Comparative Example 1>
A polycarbonate plate with a size of 170 mm square and a thickness of 6 mm was sandwiched between two stainless steel plates with a size of 200 mm square. After that, it was inserted into a mini-test press (manufactured by Toyo Seiki Seisakusho Co., Ltd., MP-WCH) set at room temperature and heated to 170° C. over 3 minutes under a press pressure of 12 MPa. After maintaining this state for 0.5 minutes, it was cooled to 30° C. over 1.5 minutes. Thus, a polycarbonate plate was produced.
One sheet of this polycarbonate plate was set in a test piece fixing jig of a cylindrical normal incident sound absorption coefficient measurement system (WinZacMTX manufactured by Nippon Onkyo Engineering Co., Ltd.), and an evaluation module for sound insulation test imitating resin glass without a hollow layer. and This soundproofing test module was subjected to a soundproofing test described later.

<Comparative Example 2>
A fine fibrous cellulose-containing sheet was prepared in the same manner as in Example 1, except that the mixed liquid was measured so that the finished basis weight of the sheet was 450 g/m ² and spread on a commercially available acrylic plate. And an adhesive layer laminated sheet was obtained. This adhesive layer laminated sheet was cut into two pieces of 150 mm square, and one polycarbonate plate with dimensions of 170 mm square and thickness of 5 mm and two polycarbonate films with dimensions of 170 mm square and thickness of 200 μm were used to obtain polycarbonate film/adhesive layer laminated sheet/polycarbonate. They were stacked in the order of plate/adhesive layer laminated sheet/polycarbonate film so that their centers were aligned. Furthermore, these were sandwiched between two stainless steel plates each having a size of 200 mm square. After that, it was inserted into a mini test press (manufactured by Toyo Seiki Seisakusho Co., Ltd., MP-WCH) set at room temperature and heated to 160° C. over 3 minutes under a press pressure of 12 MPa. After maintaining this state for 0.5 minutes, it was cooled to 30° C. over 1.5 minutes. Through the above procedure, a resin molding having a laminated structure containing a sheet containing fine fibrous cellulose, an adhesive layer, and an amorphous resin was obtained. In this resin molding, the ends of the fine fibrous cellulose-containing sheet were covered with an amorphous resin.
One sheet of this resin molded body was set in a test piece fixing jig of a cylindrical vertical incidence transmission loss measurement system (WinZacMTX manufactured by Nippon Acoustic Engineering Co., Ltd.), and evaluation for sound insulation test simulating resin glass without a hollow layer made into a module. This soundproofing test module was subjected to a soundproofing test described later. was used, and the soundproofing performance was evaluated with one resin molding without providing a hollow layer.

<Measurement>
The fine fibrous cellulose dispersions and resin moldings obtained in Examples 1 to 19 and Comparative Examples 1 and 2 were measured according to the following methods.

[Measurement of Phosphorus Acid Group Amount]
In the measurement of the phosphate group content (phosphoric acid group or phosphite group content), ion-exchanged water is first added to the target fine fibrous cellulose to prepare a slurry having a solid content concentration of 0.2% by mass. did. The obtained slurry was treated with an ion-exchange resin and then titrated with an alkali for measurement.
The ion-exchange resin treatment was carried out by adding 1/10 by volume of a strongly acidic ion-exchange resin (Amberjet 1024; manufactured by Organo Co., Ltd., conditioned) to the fine fibrous cellulose-containing slurry and shaking for 1 hour. After that, the slurry was separated from the resin by pouring it onto a mesh with an opening of 90 μm.
In the titration with alkali, 0.1 N sodium hydroxide aqueous solution is added to the fine fibrous cellulose-containing slurry after treatment with the ion exchange resin, and 10 μL of 0.1 N sodium hydroxide solution is added every 5 seconds. was measured. The titration was performed while nitrogen gas was blown into the slurry from 15 minutes before the start of the titration. In this neutralization titration, two points where the increment (the differential value of the pH with respect to the amount of alkali added) are maximized are observed in the curve obtained by plotting the measured pH against the amount of alkali added. Among these, the maximum point of the increment obtained first when the alkali is first added is called the first end point, and the maximum point of the increment obtained next is called the second end point (Fig. 7). 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. Also, the amount of alkali required from the start of titration to the second end point is 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 was divided by the solid content (g) in the slurry to be titrated to obtain the amount of phosphate group (mmol/g).

[Measurement of carboxy group content]
The amount of carboxyl groups in the fine fibrous cellulose (equal to the amount of carboxyl groups in the TEMPO oxidized pulp) was adjusted to 0.0 by adding deionized water to the fine fibrous cellulose dispersion containing the target fine fibrous cellulose. It was measured by titration with an alkali after treatment with an ion-exchange resin at 2% by mass. The treatment with an ion-exchange resin is carried out by adding 1/10 by volume of a strongly acidic ion-exchange resin (Amberjet 1024; manufactured by Organo Co., Ltd., conditioned) to a slurry containing 0.2% by mass of fine fibrous cellulose, followed by shaking for 1 hour. After being treated, the slurry was separated from the resin by pouring it onto a mesh with an opening of 90 μm.
In addition, the titration using an alkali was performed by measuring the change in the pH value of the slurry while adding a 0.1N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after treatment with the ion-exchange resin. . Observing the change in pH while adding an aqueous sodium hydroxide solution yields a titration curve as shown in FIG. As shown in FIG. 8, in this neutralization titration, in the curve plotting the measured pH against the amount of alkali added, there is one point where the increment (the differential value of pH with respect to the amount of alkali added) is maximum. 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. 8 is called the first region. The amount of alkali required in the first region is equal to the amount of carboxyl groups in the slurry used for titration. Then, by dividing the alkali amount (mmol) required in the first region of the titration curve by the solid content (g) in the fine fibrous cellulose-containing slurry to be titrated, the introduction amount of the carboxy group (mmol/g ) was calculated.
The amount of carboxy group introduced (mmol/g) described above indicates the amount of substituents per 1 g of mass of fibrous cellulose when the counter ion of the carboxy group is hydrogen ion (H ⁺ ).

[Measurement of sulfur oxoacid group content]
The obtained cellulose fibers were subjected to wet incineration using perchloric acid and concentrated nitric acid, diluted at an appropriate ratio, and the amount of sulfur was measured by ICP emission spectrometry. The amount of sulfur oxoacid groups (unit: mmol/g) was obtained by dividing this amount of sulfur by the absolute dry mass of the cellulose fiber tested.

[Measurement of xanthate base amount]
The xanthate group content was measured by the Bredee method. Specifically, 40 mL of a saturated ammonium chloride solution was added to 1.5 parts by mass of fibrous cellulose (absolute dry mass), mixed well while crushing the sample with a glass rod, and left to stand for about 15 minutes. GS-25) and washed thoroughly with saturated ammonium chloride solution. The sample was placed in a 500 mL tall beaker together with the GFP filter paper, and 50 mL of 0.5 M sodium hydroxide solution (5°C) was added and stirred. After standing for 15 minutes, it was neutralized with 1.5M acetic acid. (Phenolphthalein indicator) After neutralization, 250 mL of distilled water was added and well stirred, and 10 mL of 1.5 M acetic acid and 10 mL of 0.05 mol/L iodine solution were added using a whole pipette. This solution was titrated with a 0.05 mol/L sodium thiosulfate solution. The amount of xanthate group was calculated from the titration amount of sodium thiosulfate and the absolute dry mass of fibrous cellulose according to the following formula.
Xanthate group amount (mmol/g) = (0.05 x 10 x 2-0.05 x sodium thiosulfate titer (mL))/1000/absolute dry mass of fibrous cellulose (g)

[Measurement of fiber width]
The fiber width of fine fibrous cellulose was measured by the following method. Each fine fibrous cellulose dispersion was diluted with water so that the cellulose concentration was 0.01% by mass or more and 0.1% by mass or less, and cast on a hydrophilized carbon film-coated grid. After drying, it was stained with uranyl acetate and observed with a transmission electron microscope (TEM, JEOL-2000EX, manufactured by JEOL Ltd.). At that time, an arbitrary image width axis was assumed in the obtained image, and the magnification was adjusted so that 20 or more fibers intersected the axis. After obtaining an observation image that satisfies these conditions, two random axes were drawn vertically and horizontally from each image, and the fiber widths of fibers intersecting the axes were visually read. Three non-overlapping observation images were taken for each dispersion, and the value of the fiber width of each fiber crossing two axes was read (20 or more x 2 x 3 = 120 or more). The number average fiber width was calculated from the fiber width thus obtained.

[Thickness]
The thickness of the fiber layer and the resin molding was measured with a constant pressure thickness gauge (PG-02, manufactured by TECLOCK CORPORATION).

<Evaluation of physical properties of resin molding>
The resin moldings obtained in Examples 1-19 and Comparative Examples 1-2 were evaluated according to the following methods.

[Flexural modulus]
A test piece having a length of 80 mm and a width of 10 mm was cut out from the resin molding. In addition, the part where a fiber layer exists was cut out about the resin molding. Using this test piece, a bending test was performed using a universal material testing machine (manufactured by A&D Co., Ltd., Tensilon RTC-1250A) under the conditions of a distance between fulcrums of 64 mm and a deflection rate of 2 mm/min in accordance with JIS K 7171:2016. . The test temperature was 23°C. The flexural modulus (GPa) was calculated from the slope of the stress-strain curve when the strain was between 0.0005 and 0.0025.

[Linear thermal expansion coefficient]
A test piece having a length of 50 mm and a width of 10 mm was cut out from the resin molding. As for the resin molding, the portion where the fine fibrous cellulose-containing sheet was present was cut out. Using this test piece, using a thermomechanical analyzer (manufactured by Seiko Instruments Inc., TMA / SS6100), the 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. The coefficient of linear thermal expansion (ppm/K) was calculated by measuring the mass and dividing the change in length by the change in temperature over the temperature range 30-80°C.

[Total light transmittance]
A test piece having a size of 50 mm square was cut out from the resin molding. As for the resin molding, the portion where the fine fibrous cellulose-containing sheet was present was cut out. Using this test piece, the total light transmittance was measured according to JIS K 7361-1:1997 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory).

[Haze]
A test piece having a size of 50 mm square was cut out from the resin molding. As for the resin molding, the portion where the fine fibrous cellulose-containing sheet was present was cut out. Using this test piece, the haze was measured according to JIS K 7136:2000 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory).

[Yellowness index (YI)]
A test piece of 50 mm square was cut out from the resin molding. As for the resin molding, the portion where the fine fibrous cellulose-containing sheet was present was cut out. Using this test piece, yellowness was measured using a color meter (manufactured by Suga Test Instruments Co., Ltd., Color Cute i) in accordance with JIS K 7373:2006.

[Evaluation of module for soundproofing test]
Using the soundproofing test modules produced in Examples 1 to 19 and Comparative Examples 1 and 2, normal incidence using an acoustic tube with an inner diameter of 40 mm was measured by a vertical incidence transmission loss measurement system (manufactured by Nippon Onkyo Engineering Co., Ltd., WinZac). Transmission loss (measurement frequency 400-5000 Hz; measurement pitch 3.9 Hz) was measured. Based on the measurement results, the soundproof performance was evaluated according to the following criteria.
A: The total transmission loss at 400 Hz to 5000 Hz is 60000 dB or more B: The total transmission loss at 400 Hz to 5000 Hz is 50000 dB or more and less than 60000 dB C: The total transmission loss at 400 Hz to 5000 Hz is less than 50000 dB Here, the total transmission loss is , and the transmission loss measured at a measurement pitch of 3.9 Hz at frequencies of 400 Hz to 5000 Hz.

It was confirmed that the resin moldings used in Examples had an improved flexural modulus and a reduced coefficient of linear thermal expansion. In addition, the double-layered resin glass obtained in Examples had excellent soundproof performance. On the other hand, the polycarbonate plate of Comparative Example 1 containing no fine fibrous cellulose had a low flexural modulus and a high coefficient of linear thermal expansion. Moreover, in Comparative Examples 1 and 2, which do not include the hollow layer, the soundproof performance was insufficient.

In addition, FIG. 10 shows an example of the layer structure of the resin molding in another embodiment. Even with such a configuration, the same effects as those of the embodiment can be obtained.

10 Fiber layer 20 Adhesive layer 30 Resin layer 40 Resin film 50 Spacer 60 Primary sealing material 70 Secondary sealing material 80 Intermediate layer 100 Resin molding 100-A Resin molding 100-B Resin molding 200 Multilayer resin glass 200

Claims (9)

A multilayer resin glass having at least two resin molded bodies and a hollow layer therebetween,
The resin molding contains fibrous cellulose with a fiber width of 1000 nm or less,
The resin molded body contains an amorphous resin,
Multi-layer resin glass. A multilayer resin glass having at least two resin molded bodies and a hollow layer therebetween,
The resin molding has a laminated structure having a fiber layer containing fibrous cellulose with a fiber width of 1000 nm or less, an adhesive layer and a resin layer in this order,
The resin layer contains an amorphous resin,
Multi-layer resin glass. 3. The double-layered resin glass according to claim 1, wherein said amorphous resin is polycarbonate. The double-layer resin glass according to any one of claims 1 to 3, wherein the thickness of at least one of the resin moldings is 200 µm or more. The multi-layer resin glass according to any one of claims 1 to 4, wherein the resin molding has a total light transmittance of 80% or more. The double-layered resin glass according to any one of claims 1 to 5, wherein the resin molding has a haze of 5% or less. The double-layer resin glass according to any one of claims 1 to 6, wherein the resin molding has a bending elastic modulus of 2.4 GPa or more. The double-layer resin glass according to any one of claims 1 to 7, wherein the resin molding has a linear thermal expansion coefficient of 70 ppm/K or less. An automobile window unit comprising the double-layered resin glass according to any one of claims 1 to 8.

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