WO2014192634A1

WO2014192634A1 - Cellulose nanofiber material and cellulose film

Info

Publication number: WO2014192634A1
Application number: PCT/JP2014/063586
Authority: WO
Inventors: 隆紀栗原
Original assignee: ハリマ化成株式会社
Priority date: 2013-05-28
Filing date: 2014-05-22
Publication date: 2014-12-04
Also published as: JP6438392B2; JPWO2014192634A1

Abstract

A cellulose nanofiber material containing a polyacrylamide resin having a charge of +1.00 mEq/g or lower, and cellulose nanofibers.

Description

Cellulose nanofiber material and cellulose film

The present invention relates to a cellulose nanofiber material and a cellulose film, and particularly relates to a cellulose nanofiber material and a cellulose film made of the cellulose nanofiber material.

Conventionally, when a gas barrier property is required in a packaging material used in various industrial fields, for example, a metal foil made of a metal such as aluminum, a vinylidene chloride film, or the like is used. However, when metal foil is used, transparent packaging material cannot be obtained, so the contents cannot be confirmed through the packaging material, and it must be treated as non-combustible when discarded. There is. Further, for example, when a vinylidene chloride film is used, there is a problem that dioxins are generated during incineration.

Therefore, a material derived from a natural product that does not contain metal or chlorine and has a low environmental load has attracted attention. As such a material, for example, a cellulose nanofiber material made of cellulose nanofiber has been proposed. It is also known to use such a cellulose nanofiber material as a sheet. Specifically, the cellulose nanofiber is provided with a film composed of cellulose nanofibers and is located in the vicinity of at least one surface in the film. However, a sheet oriented substantially parallel to the film surface has been proposed (see Patent Document 1).

JP 2011-202101 A

On the other hand, although the sheet described in Patent Document 1 is excellent in transparency and gas barrier properties, there is a problem that mechanical properties such as strength are not sufficient.

An object of the present invention is to provide a cellulose nanofiber material having excellent mechanical properties and a cellulose film comprising the cellulose nanofiber material.

The cellulose nanofiber material of the present invention is characterized by containing cellulose nanofiber and a polyacrylamide resin having a charge of +1.00 meq / g or less.

In the cellulose nanofiber material of the present invention, the content ratio of the polyacrylamide resin is preferably 30 parts by mass or less with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. It is.

In the cellulose nanofiber material of the present invention, it is preferable that the total of the charge of the cellulose nanofiber and the charge of the polyacrylamide resin is 0.90 or less.

In the cellulose nanofiber material of the present invention, it is preferable that the cellulose nanofiber and the polyacrylamide resin are both anionic.

The cellulose film of the present invention is characterized by comprising a cellulose nanofiber material.

Since the cellulose nanofiber material and the cellulose film of the present invention contain cellulose nanofibers and a polyacrylamide resin having a charge of +1.00 meq / g or less, they have excellent mechanical properties.

FIG. 1 shows the tensile strength and Young's modulus of the films obtained in Examples 2 to 4 and Comparative Examples 1 to 6. FIG. 2 shows the tensile strength and Young's modulus of the films obtained in Examples 3, 6, 8, 10, 12, 14, 16 and Comparative Example 9. FIG. 3 shows the relative values of the tensile strength of the films obtained in Examples 1 to 16 and Comparative Examples 1, 9 and 10. FIG. 4 shows the relative values of the tensile strength of the films obtained in Examples 17 to 30 and Comparative Example 7. FIG. 5 shows the relative values of tensile strength of the films obtained in Examples 31 to 50 and Comparative Examples 8, 11 and 12.

The cellulose nanofiber material of the present invention contains cellulose nanofiber (CNF) and polyacrylamide resin (PAM).

Cellulose nanofibers are obtained by defibrating a cellulose raw material that is a bundle of microfibrils (nanofibers).

Examples of the cellulose raw material include purified cellulose isolated from cellulose biosynthetic systems such as plants, animals, and bacteria-producing gels. Specifically, for example, coniferous pulp, hardwood pulp, cotton pulp ( For example, cotton linter, cotton lint, etc.), pulps such as non-wood pulp (eg, straw pulp, bagasse pulp, etc.), bacterial cellulose, cellulose isolated from sea squirt, cellulose isolated from seaweed, etc. It is done.

These cellulose raw materials can be used alone or in combination of two or more.

As the cellulose raw material, pulps are preferable, and coniferous pulp is more preferable.

The method for defibrating the cellulose raw material is not particularly limited, and a known method can be adopted. For example, a method of using a N-oxyl compound as a catalyst and oxidizing the cellulose raw material to defibrate can be mentioned. In such a method, for example, a method described in JP 2008-1728 A, International Publication WO 2009/069641 and the like can be used.

Specifically, in this method, first, the cellulose raw material is dispersed in water to prepare a dispersion, and the cellulose raw material is oxidized in the presence of the N-oxyl compound in the dispersion.

The concentration of the cellulose raw material in the dispersion is not particularly limited, but is set to, for example, about 5% by mass with respect to the total amount of the dispersion.

Further, in this method, as the cellulose raw material, a material stored in a never dry state (undried state) after isolation and purification is preferably used. By storing in a never-dry state, it is possible to keep the microfibril bundle in an easily swellable state, so that the cellulose raw material can be efficiently defibrated and cellulose nanofibers having a small fiber diameter can be obtained. it can.

If necessary, the cellulose raw material can be beaten in advance to increase its surface area. Thereby, a cellulose raw material can be defibrated efficiently and productivity can be improved.

Examples of the N-oxyl compound include 2,2,6,6-tetramethylpiperidine-N-oxyl (hereinafter abbreviated as TEMPO) and derivatives thereof.

Examples of TEMPO derivatives include 4-acetamido-TEMPO, 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO, and the like.

These N-oxyl compounds can be used alone or in combination of two or more.

Further, as the N-oxyl compound, TEMPO is preferable.

The blending ratio of the N-oxyl compound is, for example, 0.1 mmol / L or more, for example, 4 mmol / L or less, preferably 2 mmol / L or less with respect to the cellulose raw material dispersion.

In this method, a co-oxidant can be added to oxidize the reduced form of the N-oxyl compound.

Examples of the co-oxidant include hypohalous acid or a salt thereof (for example, alkali metal salt, etc.), halous acid or a salt thereof, perhalogen acid or a salt thereof, hydrogen peroxide, a perorganic acid, or the like. Preferably, an alkali metal salt of hypohalous acid is used.

Examples of the alkali metal salt of hypohalous acid include sodium hypochlorite and sodium hypobromite, and preferably sodium hypochlorite.

These cooxidants can be used alone or in combination of two or more.

The mixing ratio of the co-oxidant is, for example, 0.5 mmol or more, and, for example, 10 mmol or less, preferably 8 mmol or less with respect to 1 g of the cellulose raw material.

In this method, a cocatalyst can also be added.

The cocatalyst can be selected, for example, depending on the co-oxidant. Specifically, for example, when an alkali metal salt of hypohalous acid is used as the co-oxidant, And alkali metal bromides such as sodium bromide and potassium bromide.

The addition amount of the cocatalyst is, for example, 1-fold molar amount or more, preferably 10-fold molar amount or more, for example, 40-fold molar amount or less, preferably 20-fold mole, relative to the N-oxyl compound. Less than the amount.

Also, the pH of the dispersion is maintained in a neutral to alkaline range, for example. Specifically, for example, it is 7 or more, preferably 8 or more, and for example, 11 or less.

The pH of the dispersion can be adjusted, for example, by adding a known acid or alkali to the dispersion at an appropriate ratio. For example, a known buffer can be added to the dispersion at an appropriate ratio. It can also be adjusted by doing.

Further, the temperature condition, pressure condition, and treatment time in the oxidation treatment of the cellulose raw material are not particularly limited, and are appropriately set.

Thereby, oxidized cellulose can be obtained. Further, in this method, if necessary, the oxidized cellulose can be purified by removing the catalyst and the like out of the system by a filtration method, a centrifugal separation method, or the like.

Next, in this method, the oxidized cellulose obtained as described above is dispersed in a dispersion medium using a dispersing device and defibrated. Thereby, the dispersion liquid of a cellulose nanofiber is obtained.

Examples of the dispersion medium include water and hydrophilic organic solvents.

Examples of the hydrophilic organic solvent include alcohols having 1 to 4 carbon atoms (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, methyl cellosolve, ethyl cellosolve, ethylene glycol, Glycerin, etc.), ethers (eg, ethylene glycol dimethyl ether, 1,4-dioxane, tetrahydrofuran, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfo Examples include killide. These dispersion media can be used alone or in combination of two or more. The dispersion medium is preferably water.

Various devices can be used as a dispersion device (defibration device). For example, a household mixer, an ultrasonic homogenizer, a high-pressure homogenizer, a biaxial kneader, a stone mill and the like, and a defibrating apparatus generally used for household and industrial production can be used. In addition, cellulose nanofibers having a small fiber diameter can be obtained more efficiently by using a strong and defibrating device such as various homogenizers and various refiners.

Note that the dispersion condition is not particularly limited, and is appropriately set according to the type of apparatus. In addition, if necessary, coarse substances such as undelivered cellulose raw materials can be removed from the resulting dispersion of cellulose nanofibers.

The cellulose nanofibers thus obtained have a maximum fiber diameter of, for example, 3 nm or more, and for example, 1000 nm or less, preferably 500 nm or less, more preferably 30 nm or less.

Further, the number average fiber diameter is, for example, 2 nm or more, and for example, 150 nm or less, preferably 100 nm or less, more preferably 10 nm or less.

If the maximum fiber diameter and the number average fiber diameter are in the above ranges, a cellulose nanofiber material having excellent mechanical properties and transparency can be obtained.

In addition, the maximum fiber diameter and the number average fiber diameter can be determined by observing with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), for example.

Further, the degree of polymerization of the cellulose nanofibers obtained by the above method is, for example, 200 or more, preferably 500 or more, and for example, 1200 or less, preferably 800 or less.

The degree of polymerization can be measured in accordance with the method of Examples described later.

Also, when obtaining the cellulose nanofibers using a TEMPO catalyst as described above, CH 2 _OH groups in the cellulose molecule is oxidized, COO ^- for reduction, cellulose nanofibers shows anionic.

Specifically, the charge of the cellulose nanofiber is, for example, −2.00 meq / g or more, preferably −1.60 meq / g or more, more preferably −1.50 meq / g or more. , Less than 0.00 meq / g, preferably less than −0.10 meq / g, and more preferably −1.00 meq / g or less.

The charge of the cellulose nanofiber can be measured according to the method of Examples described later.

Moreover, the amount of carboxy groups of the cellulose nanofibers obtained using the TEMPO catalyst with respect to the mass of the cellulose raw material is, for example, 1.00 mmol / g or more, preferably 1.30 mmol / g or more. 0.000 mmol / g or less, preferably 1.85 mmol / g or less.

In addition, the carboxy group amount of the cellulose nanofiber with respect to the mass of the cellulose raw material is measured according to the method of Examples described later.

In addition, the method for obtaining cellulose nanofibers is not limited to the above-described method, and other methods, for example, a method of treating with the above dispersion apparatus without using a TEMPO catalyst to form nanofibers, for example, acid A hydrolysis method or the like can also be employed.

Examples of the polyacrylamide resin include acrylamide homopolymers (polyacrylamide) and copolymers mainly composed of acrylamide.

A copolymer containing acrylamide as a main component means that, among the units constituting the copolymer, the unit derived from acrylamide is 50% by mass or more, preferably 80% by mass or more, and the remainder is copolymerized with acrylamide. Defined as a copolymer that is a unit derived from a possible monomer.

Examples of monomers copolymerizable with acrylamide include nonionic monomers, anionic monomers, and cationic monomers.

Examples of nonionic monomers include diacetone acrylamide, alkyl acrylate, hydroxy acrylate, vinyl acetate, styrene, α-methyl styrene, and the like.

Examples of anionic monomers include monocarboxylic acid monomers (eg, acrylic acid, methacrylic acid, crotonic acid, etc.), dicarboxylic acid monomers (eg, maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.), vinyl groups And organic acid monomers such as sulfonic acid monomers having vinyl (for example, vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropanoic acid, etc.). Further, salts of these organic acid monomers such as sodium salt and potassium salt can also be used.

Examples of the cationic monomer include a monomer having a tertiary amino group. Specifically, for example, a (meth) acrylic acid ester derivative having a tertiary amino group (for example, dialkylaminoethyl (meth)) is used. Acrylate (for example, dimethylaminoethyl acrylate, etc.), dialkylaminopropyl (meth) acrylate, etc.) (meth) acrylamide derivative having tertiary amino group (for example, dialkylaminoethyl (meth) acrylamide, dialkylaminopropyl (meth)) Acrylamide, (meth) acrylamide-3-methylbutyldimethylamine, etc.). Moreover, the salt of the monomer which has the said tertiary amino group can also be used. Examples of the salt include inorganic salts such as hydrochloride and sulfate, and organic salts such as formate and acetate. Furthermore, for example, a quaternary salt in which a tertiary amino group is quaternized with methyl chloride (methyl chloride), methyl bromide, benzyl chloride, benzyl bromide, dimethyl sulfate, epichlorohydrin, or the like can be mentioned.

These copolymerizable monomers can be used alone or in combination of two or more.

For example, if a nonionic monomer is used as a monomer to be copolymerized with acrylamide, a nonionic polyacrylamide resin can be obtained, and if an anionic monomer is used, an anionic polyacrylamide resin can be obtained. Furthermore, when an anionic monomer and a cationic monomer are used in combination as monomers to be copolymerized with acrylamide, an amphoteric polyacrylamide resin can be obtained. Preferably, an anionic monomer is used to obtain an anionic polyacrylamide resin. Polyacrylamide obtained without using a copolymerizable monomer is also classified as a nonionic polyacrylamide resin.

In order to obtain a polyacrylamide resin, for example, acrylamide and, if necessary, a monomer copolymerizable with the acrylamide are blended and polymerized by a known method such as emulsion polymerization.

Specifically, for example, a polyacrylamide resin can be obtained by charging the above-mentioned various monomers and water in a predetermined reaction vessel, and appropriately mixing and polymerizing a catalyst, a crosslinking agent, a chain transfer agent, and the like.

In this method, it is possible to perform polymerization while dropping a part or all of the monomer into the reaction vessel.

The catalyst is not particularly limited as long as it is a radical polymerization initiator usually used in a polymerization reaction in an aqueous solution as a polymerization initiator. For example, a peroxide (for example, hydrogen peroxide, benzoyl peroxide, t- Butyl peroxide), persulfates (eg, ammonium persulfate, sodium persulfate, potassium persulfate, etc.), bromates (eg, sodium bromate, potassium bromate, etc.), perborates (eg, perboron) Acid sodium). In addition, a redox catalyst or an azo catalyst in which these are combined with a reducing agent such as sulfite, hydrogen sulfite, transition metal salt, organic amine, or the like can also be used. These polymerization initiators can be used alone or in combination of two or more.

The mixing ratio of these catalysts is, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and for example, 10% by mass or less, preferably, based on the total mass of the monomers used. 4% by mass or less. The catalyst may be charged all at once, but may be dividedly added in a plurality of times.

Examples of the crosslinking agent include bifunctional crosslinking agents (for example, methylene bis (meth) acrylamide, ethylene bis (meth) acrylamide, ethylene glycol di (meth) acrylamide, diethylene glycol di (meth) acrylamide, triethylene glycol di (meth)). Acrylamide, divinylbenzene, diallylacrylamide, etc.), multifunctional crosslinking agents (eg 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, pentaerythritol triacrylate, trimethylolpropane acrylate, di And acryloylimide) and N-substituted acrylamide monomers (for example, dimethylacrylamide, diacetone acrylamide, isopropylacrylamide) and the like. These crosslinking agents can be used alone or in combination of two or more.

The blending ratio of these crosslinking agents is, for example, 0.005 mol% or more, preferably 0.01 mol% or more, and for example, 1 mol% or less, preferably, based on the total amount of monomers used. It is 0.2 mol% or less.

As chain transfer agents, in addition to isopropyl alcohol, mercaptos (for example, mercaptoethanol, thiourea, thioglycolic acid, mercaptopropionic acid, thiosalicylic acid, thiolactic acid, aminoethanethiol, thioglycerol, thiomalic acid, etc.), allyls (For example, allyl alcohol, sodium allyl sulfonate, sodium methallyl sulfonate, etc.). These chain transfer agents can be used alone or in combination of two or more.

The mixing ratio of these chain transfer agents is, for example, 0.01 mol% or more, preferably 0.02 mol% or more, for example, 10 mol% or less, preferably, based on the total amount of monomers used. 4 mol% or less.

Polymerization temperature is, for example, 40 ° C. or higher, and for example, 100 ° C. or lower. The polymerization time is, for example, 0.5 hours or longer, and for example, 8 hours or shorter.

Thereby, a polyacrylamide resin can be obtained.

In this method, the obtained polyacrylamide-based resin can also be modified. Specifically, first, polyacrylamide is synthesized, and then the Mannich reaction is performed on the obtained polyacrylamide by a known method. The polyacrylamide obtained by the above method may be subjected to a Hofmann decomposition reaction by a known method to be cation-modified.

The charge of the polyacrylamide resin thus obtained varies depending on the type and blending amount of the monomer used, but is, for example, -2.00 meq / g or more, preferably -1.20 meq / g or more. For example, +1.00 meq / g or less, preferably +0.60 meq / g or less, more preferably +0.10 meq / g or less, further preferably 0.00 meq / g or less, and particularly preferably −0.50 meq. / G or less, particularly preferably −1.00 meq / g or less.

If the charge of the polyacrylamide resin is within the above range, a cellulose nanofiber material having excellent mechanical properties can be obtained.

The polyacrylamide resin thus obtained has a weight average molecular weight of, for example, 100,000 or more, preferably 500,000 or more, and, for example, 8 million or less, preferably 5 million or less.

In addition, a weight average molecular weight can be measured based on the method of the Example mentioned later.

The shape and structure of the cellulose nanofiber material composed of the cellulose nanofiber and the acrylamide resin are not particularly limited and can be appropriately selected.

Specific examples include a cellulose film, a cellulose sheet, a sponge-like structure, a gel-like structure, and preferably a cellulose film.

Hereinafter, a method for producing a cellulose film will be described in detail.

In the production of the cellulose film of the present invention, first, the cellulose nanofibers and the polyacrylamide resin are dispersed in a dispersion medium to prepare a dispersion.

Examples of the dispersion medium include water and the above-described hydrophilic organic solvent. These dispersion media can be used alone or in combination of two or more. The dispersion medium is preferably water.

In this method, the cellulose nanofiber and the polyacrylamide resin are appropriately selected according to the purpose and application. The total of the charge of the cellulose nanofiber and the charge of the polyacrylamide resin is, for example, 0. 90 or less, preferably 0.50 or less, more preferably 0.00 or less, still more preferably -0.10 or less, particularly preferably -1.00 or less, particularly preferably -1.50 or less. Particularly preferred is −2.00 or less, and usually −4.00 or more.

Here, the total charge is the sum of the charge value of the cellulose nanofiber (dimensionless) and the charge value of the polyacrylamide resin (dimensionless), and their blending ratio Without depending on the type of cellulose nanofiber and polyacrylamide resin used.

That is, in this method, preferably, the cellulose nanofiber and the polyacrylamide resin to be used are selected so that the sum of their charges falls within the above range.

If the sum of the charge of the cellulose nanofiber and the charge of the polyacrylamide resin is within the above range, a cellulose film having excellent mechanical properties can be obtained.

In this method, preferably, the cellulose nanofiber and the polyacrylamide resin are both anionic. That is, in this method, an anionic cellulose nanofiber is preferably used as the cellulose nanofiber, and an anionic polyacrylamide resin is used as the polyacrylamide resin.

If the cellulose nanofiber and the polyacrylamide resin are both anionic, the cellulose nanofiber and the polyacrylamide resin are repelled by negative charges, so that the dispersibility can be improved and the mechanical properties can be improved. Can be obtained.

The blending ratio of the cellulose nanofiber and the polyacrylamide resin in the dispersion is such that the blending ratio of the cellulose nanofiber is, for example, 50 parts by mass or more, preferably 100 parts by mass of the total mass. 60 parts by mass or more, more preferably 70 parts by mass or more, still more preferably 75 parts by mass or more, and for example, 99 parts by mass or less, preferably 97 parts by mass or less, more preferably 95 parts by mass or less. It is. The blending ratio of the polyacrylamide resin is, for example, 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and for example, 50 parts by mass or less, preferably 40 parts by mass. It is 30 parts by mass or less, more preferably 25 parts by mass or less.

If the blending ratio of the cellulose nanofiber and the polyacrylamide resin is within the above range, a cellulose film having excellent mechanical properties can be obtained.

The method for dispersing the cellulose nanofibers and the polyacrylamide resin in a dispersion medium is not particularly limited, and may be stirred by a known method, and a dispersing device can also be used.

Examples of such a dispersing device include a home mixer, an ultrasonic homogenizer, and a high-pressure homogenizer. The dispersion condition is not particularly limited, and is set as appropriate according to the type of apparatus.

The pH of the obtained dispersion is, for example, 4 or more, preferably 6 or more, and for example, 10 or less, preferably 8 or less.

Next, in this method, the obtained dispersion is dried in a container.

Examples of the drying method include a freeze-drying method when the dispersion medium is water, and a drum dryer drying method when the dispersion medium is a mixed liquid of water and a hydrophilic organic solvent. And spray drying using a spray dryer. The drying conditions are not particularly limited and can be set as appropriate.

Thereby, a cellulose film can be obtained.

In addition, the above-described dispersion liquid is coated on one surface or both surfaces of the base material by coating and drying on the surface of the base material (for example, paper, resin film (for example, polyethylene terephthalate)). A cellulose nanofiber layer made of a film can also be formed.

As a coating method, for example, the coating can be performed using a known coating machine such as a roll coater or a bar coater. Moreover, as a drying method, a known dryer can be used.

Thereby, a cellulose nanofiber layer having excellent mechanical properties can be formed as a gas barrier layer with respect to the substrate, and a gas barrier material having excellent mechanical properties, which is composed of the substrate and the cellulose nanofiber layer, can be obtained.

Such a cellulose nanofiber material and a cellulose film have excellent mechanical properties because they contain cellulose nanofiber and a polyacrylamide resin having a charge of +1.00 meq / g or less.

In addition, the content ratio of the cellulose nanofibers and the polyacrylamide resin in the cellulose film is such that the content ratio of the cellulose nanofibers is 50 parts by mass or more, preferably 60 masses with respect to the total mass of 100 parts by mass. Part or more, more preferably 70 parts by weight or more, still more preferably 75 parts by weight or more, and for example 99 parts by weight or less, preferably 97 parts by weight or less, more preferably 95 parts by weight or less. . The content of the polyacrylamide resin is, for example, 1 part by mass or more, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and for example, 50 parts by mass or less, preferably 40 parts by mass. It is 30 parts by mass or less, more preferably 25 parts by mass or less.

If the blending ratio of the cellulose nanofiber and the polyacrylamide resin is within the above range, the cellulose film exhibits excellent mechanical properties, in particular, excellent tensile strength and Young's modulus.

Specifically, the tensile strength of the cellulose film is, for example, 50 MPa or more, preferably 150 MPa or more, more preferably 200 MPa or more, further preferably 250 MPa or more, and usually 500 MPa or less.

In addition, the tensile strength can be measured in accordance with a method of an example described later.

Further, specifically, the Young's modulus of the cellulose film is, for example, 4 GPa or more, preferably 10 GPa or more, more preferably 12 GPa or more, still more preferably 14 GPa or more, and usually 20 GPa or less.

The Young's modulus can be measured in accordance with the method of the example described later.

The thickness of the cellulose film is, for example, 1 μm or more, preferably 2 μm or more, more preferably 5 μm or more, and for example, less than 100 μm, preferably 50 μm or less, more preferably 30 μm or less, and further preferably. Is 15 μm or less.

In addition, when manufacturing a cellulose nanofiber material as a cellulose sheet, the thickness is 100 micrometers or more, for example, Preferably, it is 200 micrometers or more, for example, is 5 mm or less.

Further, the cellulose film or the cellulose sheet may be a single layer, or a plurality of layers may be laminated.

Moreover, the obtained cellulose film is excellent in transparency. Specifically, the light transmittance of the cellulose film at a wavelength of 600 nm is, for example, 50% or more, preferably 65% or more, more preferably 75% or more, and further preferably 85% or more. % Or less.

In addition, the light transmittance of a cellulose film can be measured based on the method of the Example mentioned later.

(Preparation Example 1)
(Preparation of cellulose nanofiber A)
(Oxidation treatment)
0.1 mmol of TEMPO and 1 mmol of sodium bromide were dissolved in a 1% by mass slurry (100 ml of distilled water) of commercially available softwood bleached pulp, and then 5 mmol of sodium hypochlorite was added and reacted.

During the reaction, 0.5 M sodium hydroxide was appropriately added to keep the pH at 10, and the reaction was terminated when no pH decrease was observed.

Thereafter, it was sufficiently washed with water to obtain a TEMPO-catalyzed oxidized pulp having a pH of about 7.
(Defibration processing)
The 0.15 mass% slurry of the TEMPO catalyst oxidized pulp obtained by the above operation was mechanically processed and defibrated. Thereafter, coarse materials such as undefibrated pulp were removed by centrifugation to obtain cellulose nanofiber A (hereinafter abbreviated as CNF-A).
(Preparation Example 2)
(Preparation of cellulose nanofiber B)
Cellulose nanofiber B (hereinafter abbreviated as CNF-B) was obtained in the same manner as in Preparation Example 1, except that 10 mmol of sodium hypochlorite was added instead of 5 mmol of sodium hypochlorite.
(Preparation Example 3)
(Preparation of cellulose nanofiber C)
Cellulose nanofiber C (hereinafter abbreviated as CNF-C) was obtained in the same manner as in Preparation Example 1 except that the fiber was disentangled only by mechanical treatment without being oxidized.

Table 1 shows the physical properties (degree of polymerization, amount of carboxy group, charge) of each cellulose nanofiber.

The degree of polymerization, the amount of carboxy groups, and the charge were measured by the following methods.
<Measurement method of degree of polymerization>
The degree of polymerization was determined by the viscosity method using the following copper ethylenediamine solution. Cellulose nanofibers that have been completely dried by treatment such as vacuum drying are dissolved in the copper ethylenediamine solution 1 to prepare a solution 2, and the viscosity is measured using a viscometer. The viscosity of the solution 2 eta, the viscosity of the solution 1 as eta _0, was determined intrinsic viscosity of the cellulose nanofiber solution [eta] by the following equation.

Intrinsic viscosity [η] = (η / η ₀ ) / {c (1 + A × η / η ₀ )}
Here, c is the concentration of cellulose nanofibers (g / dL), A is a value determined by the type of solution 1, and A when a 0.5 M copper ethylenediamine solution is used is 0.28. is there.

Further, the degree of polymerization DP is obtained from the following formula.

DP ^a = [η] / K
Here, K and a are values determined by the type of polymer and the solvent used. In the case of cellulose dissolved in copper ethylenediamine, K is 5.7 × 10 ⁻³ and a is 1.

The viscometer is preferably a capillary viscometer, examples of which include a Canon-Fenske viscometer.
<Measurement method of carboxy group amount>
Using the cellulose nanofibers obtained in each preparation example, 60 mL of a 0.5 to 1% by mass dispersion was prepared. Next, the pH was adjusted to about 2.5 with a 0.1 M aqueous hydrochloric acid solution, and then a 0.05 M aqueous sodium hydroxide solution was added dropwise to measure the electrical conductivity. Thereafter, the dropping was stopped when the pH of the dispersion reached 11. And the amount of carboxy groups was computed using the following formula from the amount (V) of sodium hydroxide consumed in the neutralization step of the weak acid where the change in electrical conductivity is gradual.

Carboxy group amount (mmol / g) = V (mL) × 0.05 (mmol / mL) / mass of cellulose nanofiber (g)
<Method for measuring charge>
Measurement was performed by a titration apparatus (PCD-04 and PCD-T3, manufactured by Mutek) using a streaming potential method. That is, an aqueous dispersion of cellulose nanofibers 0.01% by mass and pH 7 was prepared as a sample. Next, 10 g of the dispersion was placed in a dedicated cell, the cell was set in a measuring instrument, and the switch was turned on. If the value shown at this time is the streaming potential before titration (unit: mV) and the value is +, the dispersion has a cationic charge, while if the value is-, the dispersion The liquid was judged to have an anionic charge. Next, in the case of a titration liquid showing a charge opposite to the charge shown by the above-mentioned flow potential before titration, that is, a dispersion liquid in which the flow potential before titration shows a cationic charge, an anion titrant is used and the flow potential before titration is used. In the case of a dispersion having an anionic charge, titration was performed using a cation titrant until the streaming potential became zero. From the titration amount when the streaming potential became 0, the charge was calculated by the following formula.

In addition, 0.0025N Poly (dialydimethylammonium Chloride) Solution (manufactured by Wako) was used as the cation titrant, and 0.0025N Potassium Polyvinyl Sulfation Solution (manufactured by Wako Corporation) was used as the anion titrant.

Charge (meq / g) = Titration volume (mL) × Titration liquid concentration (N) / (Dispersion volume (g) × Dispersion liquid concentration (%)) × 100

(Preparation Example 4)
(Preparation of polyacrylamide resin)
68.0 g of acrylamide, 6.6 g of acrylic acid, 0.05 g of dimethyl acrylamide, 0.25 g of sodium methallylsulfonate and 0.05 g of ammonium persulfate were blended and copolymerized in water to obtain a charge of −1.06 meq. / G, a polyacrylamide resin A (hereinafter abbreviated as PAM-A) having a weight average molecular weight of 2,060,000 was obtained.

The charge was measured by the same procedure as the method for measuring the charge of cellulose nanofibers, except that an aqueous dispersion of 0.05% by mass of polyacrylamide resin and pH 7 was used as a sample. The weight average molecular weight was measured by the following method (the same applies hereinafter).
<Measurement method of weight average molecular weight>
The weight average molecular weight was measured by the SEC (size exclusion chromatography) method. POLY (ETHYLENE OXIDE) (TSK Standard, SE-8 (weight average molecular weight 100,000), manufactured by Tosoh Corporation) was used as a standard substance, and TDA302 (one guard column, two columns, concentration detector, optical detector) was used as a detector. A scattering detector and a viscosity detector were mounted, and measurement was performed using a VISCOTEK company).
(Preparation Example 5)
68.9 g of acrylamide, 10.2 g of itaconic acid, 0.10 g of dimethylacrylamide, 0.25 g of sodium methallyl sulfonate, and 0.10 g of ammonium persulfate are blended and copolymerized in water to obtain a charge of 1.-1. A polyacrylamide resin B (hereinafter abbreviated as PAM-B) having 64 meq / g and a weight average molecular weight of 1.9 million was obtained.
(Preparation Example 6)
71.3 g of acrylamide, 3.3 g of acrylic acid, 0.05 g of methylenebisacrylamide, 0.20 g of sodium methallyl sulfonate, and 0.10 g of ammonium persulfate were blended and copolymerized in water to give a charge of −0. A polyacrylamide resin C (hereinafter abbreviated as PAM-C) having a molecular weight of 0.77 meq / g and a weight average molecular weight of 210,000 was obtained.
(Preparation Example 7)
74.5 g of acrylamide, 0.05 g of dimethylacrylamide, 0.25 g of sodium methallyl sulfonate, and 0.10 g of ammonium persulfate were blended and copolymerized in water to have a charge of 0.00 meq / g and a weight average molecular weight of 205. Of polyacrylamide resin D (hereinafter abbreviated as PAM-D).
(Preparation Example 8)
A mixture of 67.6 g of acrylamide, 18.7 g of dimethylaminoethyl methacrylate methyl chloride quaternary salt, 0.05 g of dimethylacrylamide, 0.20 g of sodium methallyl sulfonate, and 0.10 g of ammonium persulfate was used together in water. Polymerization was performed to obtain a polyacrylamide resin E (hereinafter abbreviated as PAM-E) having a charge of +1.27 meq / g and a weight average molecular weight of 1.89 million.
(Preparation Example 9)
66.9 g of acrylamide, 10.8 g of dimethylaminoethyl acrylate methyl chloride quaternary salt, 3.8 g of acrylic acid, 0.10 g of methylenebisacrylamide, 0.25 g of sodium methallylsulfonate, 0.10 g of ammonium persulfate, And copolymerized in water to obtain a polyacrylamide resin F (hereinafter abbreviated as PAM-F) having a charge of -0.06 meq / g and a weight average molecular weight of 2,100,000.
(Preparation Example 10)
A mixture of 74.0 g of acrylamide, 2.1 g of dimethylaminoethyl acrylate methyl chloride quaternary salt, 0.05 g of dimethylacrylamide, 0.25 g of sodium methallylsulfonate, and 0.10 g of ammonium persulfate was used together in water. Polymerization was performed to obtain a polyacrylamide resin G (hereinafter abbreviated as PAM-G) having a charge of +0.09 meq / g and a weight average molecular weight of 2.1 million.
(Preparation Example 11)
70.3 g of acrylamide, 10.5 g of dimethylaminoethyl acrylate methyl chloride quaternary salt, 0.05 g of dimethylacrylamide, 0.25 g of sodium methallylsulfonate, and 0.10 g of ammonium persulfate were blended together in water. Polymerization was performed to obtain a polyacrylamide resin H (hereinafter abbreviated as PAM-H) having a charge of +0.52 meq / g and a weight average molecular weight of 2,040,000.

Table 2 shows the physical properties (ionicity, charge) of each polyacrylamide resin.

(Example 1)
(Manufacture of cellulose film)
Using CNF-A as the cellulose nanofiber and PAM-A as the polyacrylamide resin, 5 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film containing at a ratio was produced.

Specifically, first, a 0.15% by mass aqueous dispersion of CNF-A and a 0.15% by mass aqueous dispersion of PAM-A were prepared, and these were added to the total amount of CNF-A and PAM-A. PAM-A was mixed at a ratio of 5 parts by mass with respect to 100 parts by mass. Next, the obtained mixed solution was poured into a petri dish and dried to produce a cellulose film having a thickness of about 10 μm.
(Example 2)
Using CNF-A as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 3)
Using CNF-A as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
Example 4
Using CNF-A as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 40 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 5)
Using CNF-A as the cellulose nanofiber and PAM-B as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 6)
Using CNF-A as the cellulose nanofiber and PAM-B as the polyacrylamide resin, 25 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 7)
Using CNF-A as the cellulose nanofiber and PAM-C as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 8)
Using CNF-A as the cellulose nanofiber and PAM-C as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
Example 9
Using CNF-A as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 10)
Using CNF-A as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 11)
Using CNF-A as the cellulose nanofiber and PAM-F as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
Example 12
Using CNF-A as the cellulose nanofiber and PAM-F as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 13)
Using CNF-A as the cellulose nanofiber and PAM-G as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 14)
Using CNF-A as the cellulose nanofiber and PAM-G as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 15)
Using CNF-A as the cellulose nanofiber and PAM-H as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 16)
Using CNF-A as the cellulose nanofiber and PAM-H as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 17)
Using CNF-B as the cellulose nanofiber and PAM-A as the polyacrylamide resin, 5 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 18)
Using CNF-B as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 19)
Using CNF-B as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 20)
Using CNF-B as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 40 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 21)
Using CNF-B as the cellulose nanofiber and PAM-B as the polyacrylamide resin, 5 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 22)
Using CNF-B as the cellulose nanofiber and PAM-B as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 23)
Using CNF-B as the cellulose nanofiber and PAM-B as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 24)
Using CNF-B as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 5 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 25)
Using CNF-B as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 26)
Using CNF-B as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 27)
Using CNF-B as the cellulose nanofiber and PAM-G as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 28)
Using CNF-B as the cellulose nanofiber and PAM-G as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 29)
Using CNF-B as the cellulose nanofiber and PAM-H as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 30)
Using CNF-B as the cellulose nanofiber and PAM-H as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 31)
Using CNF-C as the cellulose nanofiber and PAM-A as the polyacrylamide resin, 5 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 32)
Using CNF-C as the cellulose nanofiber and PAM-A as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 33)
Using CNF-C as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 15 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 34)
Using CNF-C as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 35)
Using CNF-C as the cellulose nanofiber and PAM-A as the polyacrylamide resin, the polyacrylamide resin is 40 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 36)
Using CNF-C as the cellulose nanofiber and PAM-B as the polyacrylamide resin, 5 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 37)
Using CNF-C as the cellulose nanofiber and PAM-B as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 38)
Using CNF-C as the cellulose nanofiber and PAM-B as the polyacrylamide resin, the polyacrylamide resin is 15 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 39)
Using CNF-C as the cellulose nanofiber and PAM-B as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 40)
Using CNF-C as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 5 parts by mass with respect to 100 parts by mass of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 41)
Using CNF-C as the cellulose nanofiber and PAM-D as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 42)
Using CNF-C as the cellulose nanofiber and PAM-D as the polyacrylamide resin, 15 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 43)
Using CNF-C as the cellulose nanofiber and PAM-D as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 44)
Using CNF-C as the cellulose nanofiber and PAM-F as the polyacrylamide resin, 5 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 45)
Using CNF-C as the cellulose nanofiber and PAM-F as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 46)
Using CNF-C as the cellulose nanofiber and PAM-F as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 47)
Using CNF-C as the cellulose nanofiber and PAM-G as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 48)
Using CNF-C as the cellulose nanofiber and PAM-G as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 49)
Using CNF-C as the cellulose nanofiber and PAM-H as the polyacrylamide resin, 10 parts by mass of the polyacrylamide resin with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Example 50)
Using CNF-C as the cellulose nanofiber and PAM-H as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Comparative Example 1)
Using CNF-A as the cellulose nanofiber, a cellulose film was produced from CNF-A alone.

Specifically, first, a 0.15 mass% aqueous dispersion of CNF-A was prepared, and the obtained dispersion was poured into a petri dish and dried to produce a cellulose film having a thickness of about 10 μm.
(Comparative Example 2)
Using PAM-A as the polyacrylamide resin, a polyacrylamide resin film was produced from PAM-A alone in the same manner as in Comparative Example 1.
(Comparative Example 3)
CNF-A is used as cellulose nanofiber, and polyvinyl alcohol (polymerization degree 1700, VF-17, charge: -0.02 meq / g, complete saponification type: saponification degree (DS) instead of polyacrylamide resin > 98%, (Nippon Vinegar-Poval)) (hereinafter abbreviated as PVA), and 10 parts by mass of polyvinyl alcohol with respect to 100 parts by mass of cellulose nanofibers and polyvinyl alcohol in total. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Comparative Example 4)
CNF-A is used as the cellulose nanofiber, and PVA is used in place of the polyacrylamide-based resin, and polyvinyl alcohol is contained in a proportion of 25 parts by mass with respect to 100 parts by mass of the total amount of cellulose nanofiber and polyvinyl alcohol. A cellulose film was produced in the same manner as in Example 1 except that the above procedure was performed.
(Comparative Example 5)
CNF-A is used as the cellulose nanofiber, and PVA is used in place of the polyacrylamide-based resin, and polyvinyl alcohol is contained in a proportion of 50 parts by mass with respect to 100 parts by mass of the total amount of cellulose nanofiber and polyvinyl alcohol. A cellulose film was produced in the same manner as in Example 1 except that the above procedure was performed.
(Comparative Example 6)
A polyvinyl alcohol film was produced in the same manner as in Comparative Example 1 from PVA alone using PVA instead of the polyacrylamide resin.
(Comparative Example 7)
Using CNF-B as the cellulose nanofiber, a cellulose film was produced in the same manner as in Comparative Example 1 from CNF-B alone.
(Comparative Example 8)
Using CNF-C as the cellulose nanofiber, a cellulose film was produced in the same manner as in Comparative Example 1 from CNF-C alone.
(Comparative Example 9)
Using CNF-A as the cellulose nanofiber and PAM-E as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Comparative Example 10)
Using CNF-A as the cellulose nanofiber and PAM-E as the polyacrylamide resin, the polyacrylamide resin is 40 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Comparative Example 11)
Using CNF-C as the cellulose nanofiber and PAM-E as the polyacrylamide resin, the polyacrylamide resin is 10 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.
(Comparative Example 12)
Using CNF-C as the cellulose nanofiber and PAM-E as the polyacrylamide resin, the polyacrylamide resin is 25 parts by mass with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. A cellulose film was produced in the same manner as in Example 1 except that it was contained in a proportion.

Tables 3 to 7 show the formulation of each example and comparative example.
(Evaluation 1) Relationship between blending ratio of polyacrylamide resin and mechanical properties The tensile strength and Young's modulus of the films obtained in Examples 2 to 4 and Comparative Examples 1 to 6 were measured by the following methods. The result is shown in FIG.
<Measurement method of tensile strength>
The film of each Example and Comparative Example was cut into a length of 30 mm, a width of 2 mm, and a thickness of 10 μm to obtain a test piece. Next, using a small desktop testing machine EZ-S (load cell capacity: 500 N, pulling speed: 1 mm / min, distance between grips: 10 mm, manufactured by Shimadzu Corporation) The test piece was pulled upward. In this test, the stress (tensile strength) was calculated from the following formula using the force (N) applied when the test piece was broken and the shape of the film (width × thickness = cross-sectional area (m ² )). Each example and comparative example were measured 10 times, and the average value was taken as the value of tensile strength.

Stress (Pa) = Force (N) / Cross-sectional area (m ² )
<Measurement method of Young's modulus>
The Young's modulus was obtained from the slope of the straight line portion (for example, the region of stress 20 to 40 MPa) in the initial stage of the stress-strain curve obtained at the time of measuring the tensile strength by the following calculation formula.

Young's modulus (Pa) = tilt × initial length (distance between grips, 10 mm) / cross-sectional area (m ² )
(Evaluation 2) Relationship between charge and mechanical properties of polyacrylamide resin The tensile strength and Young's modulus of the films obtained in Examples 3, 6, 8, 10, 12, 14, 16 and Comparative Example 9 were Measurement was performed in the same manner as in Evaluation 1. The result is shown in FIG.
(Evaluation 3) Regarding the relationship between the charge and blending ratio of polyacrylamide resin and mechanical properties in the case of using cellulose nanofiber A Examples 1 to 16 Tensile strength of the films obtained in Comparative Examples 1, 9 and 10 Was measured in the same manner as in Evaluation 1. And the relative value (tensile strength index) with respect to the comparative example 1 of the tensile strength of each Example was set to 100 as the tensile strength of the comparative example 1. The result is shown in FIG.
(Evaluation 4) Regarding the relationship between the charge and blending ratio of polyacrylamide resin and mechanical properties when cellulose nanofiber B is used, the tensile strength of the films obtained in Examples 17 to 30 and Comparative Example 7 was evaluated. Measurement was performed in the same manner as in 1. And the relative value with respect to the comparative example 7 of tensile strength was computed similarly to the evaluation 3. FIG. The result is shown in FIG.
(Evaluation 5) Relationship between electric properties and blending ratio of polyacrylamide resin and mechanical properties when cellulose nanofiber C is used Tensile tension of the films obtained in Examples 31 to 50 and Comparative Examples 8, 11 and 12 The strength was measured in the same manner as in Evaluation 1. And the relative value with respect to the comparative example 8 of tensile strength was computed similarly to the evaluation 3. FIG. The result is shown in FIG.

Tables 3 to 7 show the tensile strength and Young's modulus obtained with the films of Examples 1 to 50 and Comparative Examples 1 to 12.
(Evaluation 6) Light Transmittance of Cellulose Film at a Wavelength of 600 nm The light transmittance of the films obtained in Examples 1 to 50 and Comparative Examples 1 to 12 was measured by the following method. As representative of the obtained measurement results, the light transmittance at a wavelength of 600 nm is shown in Tables 3 to 7.
<Measurement method of light transmittance>
The light transmittance in the wavelength region of 400 nm to 800 nm was measured using an ultraviolet-visible near-infrared spectrophotometer V-670 (manufactured by JASCO Corporation). Specifically, the films obtained in each Example and Comparative Example were sandwiched and set in a dedicated holder, and the light transmittance in the wavelength region of 400 nm to 800 nm was continuously measured at a scanning speed of 100 nm / min.

Although the above invention has been provided as an exemplary embodiment of the present invention, this is merely an example and should not be interpreted in a limited manner. Variations of the present invention that are apparent to one of ordinary skill in the art are within the scope of the following claims.

The cellulose nanofiber material and the cellulose film of the present invention are suitably used as packing materials in various industrial fields.

Claims

A cellulose nanofiber material comprising cellulose nanofiber and a polyacrylamide resin having a charge of +1.00 meq / g or less.
The cellulose nanofiber according to claim 1, wherein a content ratio of the polyacrylamide resin is 30 parts by mass or less with respect to 100 parts by mass of the total amount of the cellulose nanofiber and the polyacrylamide resin. Fiber material.
The charge of the cellulose nanofibers;
2. The cellulose nanofiber material according to claim 1, wherein the total of the charges of the polyacrylamide resin is 0.90 or less.
The cellulose nanofibers;
The cellulose nanofiber material according to claim 1, wherein both the polyacrylamide resins are anionic.
A cellulose film comprising a cellulose nanofiber material containing cellulose nanofiber and a polyacrylamide resin having a charge of +1.00 meq / g or less.