JP7065797B2 - Fibrous cellulose-containing composition, its production method, and membrane - Google Patents

Description

The present invention relates to a fine fibrous cellulose-containing composition, a method for producing the same, and a membrane thereof.

In recent years, due to the substitution of petroleum resources and the growing environmental awareness, materials using reproducible natural fibers have been attracting attention. Among natural fibers, fibrous cellulose having a fiber diameter of 10 μm or more and 50 μm or less, particularly fibrous cellulose (pulp) derived from wood, has been widely used mainly as paper products.

As the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. In recent years, a sheet composed of such fine fibrous cellulose and a composite sheet containing a fine fibrous cellulose-containing sheet and a resin have been developed. Further, since the fine fibrous cellulose can exert a thickening effect, it is also considered to use the fine fibrous cellulose as a thickener for various purposes.

As a method for producing a dispersion of fine fibrous cellulose, Patent Document 1 describes that chemically modified cellulose fibers are defibrated to obtain a cellulose nanofiber dispersion. Patent Document 1 describes that an enzyme-treated cellulose fiber may be used as the chemically modified cellulose fiber. Further, Patent Document 2 describes that finely divided cellulose oxide is made into an aqueous medium to obtain a dispersion liquid of fine cellulose fibers. Patent Document 2 describes that the cellulose raw material may be treated with an enzyme.

Japanese Unexamined Patent Publication No. 2017-2136 JP-A-2015-221844

The present inventors have considered the use of fine fibrous cellulose for the purpose of reinforcing paints. However, since the fine fibrous cellulose has a high viscosity, it is difficult to add a sufficient amount of the fine fibrous cellulose for reinforcement in the usage where the increase in viscosity is not desired. For example, when forming a coating film with a paint, the lower the viscosity of the fine fibrous cellulose, the better the coating suitability. An object to be solved by the present invention is to provide a cellulose-containing composition having excellent coatability, a method for producing the same, and a film.

As a result of diligent studies to solve the above problems, the present inventors have a fiber width of 1000 nm or less and contain a phosphite group or a fibrous cellulose having a substituent derived from the phosphite group. It has been found that a cellulose-containing composition having excellent coatability can be provided by adding an enzyme to the composition to adjust the viscosity of the composition. The present invention has been completed based on these findings.
The present invention has the following configurations.

[1] A cellulose-containing composition containing a protein and a fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from the phosphite group, wherein the protein contains an enzyme. The protein content is 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of the fibrous cellulose, and the solid content concentration of the fibrous cellulose is 0.4% by mass at 25 ° C. and 3 rpm. A cellulose-containing composition having a viscosity of 10 mPa · s or more and 11000 mPa · s or less measured under the above conditions.
[2] The cellulose-containing composition according to [1], wherein the content of the protein is 1 × 10 ^-7 parts by mass or more with respect to 1 part by mass of the fibrous cellulose.
[3] A cellulose-containing composition having a fiber width of 1000 nm or less and containing a fibrous cellulose having a phosphite group or a substituent derived from the phosphite group and a protein, wherein the protein contains an enzyme. The endoglucanase activity of the enzyme is 840 U / L or less, and the viscosity measured under the conditions of 25 ° C. and 3 rpm with a solid content concentration of 0.4% by mass of the fibrous cellulose is 10 mPa · s or more and 11000 mPa · s or less. Is a cellulose-containing composition.
[4] The cellulose-containing composition according to [3], wherein the endoglucanase activity of the enzyme is 0.084 U / L or more.
[5] The cellulose-containing composition according to any one of [1] to [4], wherein the degree of polymerization of the fibrous cellulose is 200 or more and 450 or less.
[6] A membrane containing a protein and a fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from the phosphite group, wherein the protein contains an enzyme and the protein. The content of the membrane is 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of the fibrous cellulose.
[7] The membrane according to [6], wherein the content of the protein is 1 × 10 ^-7 parts by mass or more with respect to 1 part by mass of the fibrous cellulose.
[8] Add an enzyme of 1 × 10 ^-3 parts by mass or less to 1 part by mass of fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from a phosphite group. A method for producing a cellulose-containing composition, which comprises a step.

According to the present invention, it is possible to provide a cellulose-containing composition having excellent coatability.

FIG. 1 is a graph showing the relationship between the amount of NaOH dropped and the pH of a fibrous cellulose-containing slurry having a phosphoric acid group. FIG. 2 is a graph showing the relationship between the amount of NaOH dropped and the pH with respect to the fibrous cellulose-containing slurry having a carboxy group.

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

(Cellulose-containing composition)
INDUSTRIAL APPLICABILITY The present invention is a cellulose-containing composition containing a fibrous cellulose (hereinafter, also referred to as fine fibrous cellulose) having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from the phosphite group, and a protein. The protein contains an enzyme, the content of the protein is 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of the fibrous cellulose, and the solid content concentration of the fibrous cellulose is 0. The present invention relates to a cellulose-containing composition having a viscosity of 10 mPa · s or more and 11000 mPa · s or less measured under the conditions of 25 ° C. and 3 rpm as 4% by mass.

The protein content may be 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of fibrous cellulose, preferably 1 × 10 ^-4 parts by mass or less, and more preferably 1 × 10 ^-5 parts by mass or less. , 5.0 × 10 ^-6 parts by mass or less is particularly preferable. The protein content is preferably 1 × 10 ^-7 parts by mass or more, more preferably 3 × 10 ^-7 parts by mass or more, and further preferably 1 × 10 ^-6 parts by mass or more with respect to 1 part by mass of fibrous cellulose.
The protein content can be controlled by adjusting the addition amount of the enzyme, adjusting the production process of the fine fibrous cellulose including the enzyme treatment, and the like. In this embodiment, the amount of protein can be adjusted, for example, depending on the timing of enzyme treatment. Good coatability can be achieved by keeping the protein content within the above range.

The protein content in the cellulose-containing composition can be determined by, for example, a burette method, a Lowry method, a fluorescence method, or a dye binding method. When determining the protein content by the Bullet method, add 4 times the amount of the Bullet drug to the bovine serum albumin aqueous solution (prepared so that the protein content is 5.0% by mass or less), mix, and mix 20. After leaving it in an environment of ℃ to 25 ℃ for 30 minutes, the absorption wavelength of 540 nm is measured using a spectrophotometer, and a calibration curve is drawn based on the measured value. Next, 4 times the amount of the burette reagent was added to the cellulose-containing composition, mixed well, left to stand in an environment of 20 ° C to 25 ° C for 30 minutes, and then the absorption wavelength of 540 nm was measured using a spectrophotometer. do. By writing the measured value on the calibration curve, the amount of protein contained in the cellulose-containing composition can be determined.

Further, the present invention is a cellulose-containing composition having a fiber width of 1000 nm or less and containing a fibrous cellulose having a phosphite group or a substituent derived from the phosphite group and a protein, wherein the protein comprises an enzyme. The endoglucanase activity of the enzyme is 840 U / L or less, and the viscosity measured under the conditions of 25 ° C. and 3 rpm with a solid content concentration of 0.4% by mass of the fibrous cellulose is 10 mPa · s or more and 11000 mPa ·. s or less, relating to a cellulose-containing composition.

The endoglucanase activity of the enzyme may be 840 U / L or less. The lower limit of the endoglucanase activity of the enzyme is preferably 0.084 U / L or more, more preferably 0.84 U / L or more, more preferably 1 U / L or more, further preferably 2 U / L or more, and 3 U / L or more. Especially preferable. The upper limit of the endoglucanase activity of the enzyme is preferably 84 U / L or less, more preferably 8.4 U / L or less, further preferably 7 U / L or less, and particularly preferably 6 U / L or less.
The endoglucanase activity of the enzyme can be controlled by adjusting the addition amount of the enzyme, adjusting the production process of the fine fibrous cellulose including the enzyme treatment, and the like. In the present embodiment, the endoglucanase activity of the enzyme can be adjusted, for example, depending on the timing of the enzyme treatment. Good coatability can be achieved by keeping the endoglucanase activity of the enzyme within the above range.

The endoglucanase activity (also referred to as EG activity) of the enzyme in the cellulose-containing composition can be measured as follows.
A substrate solution of carboxymethyl cellulose having a concentration of 1% (W / V) (concentration: 100 mM, containing a sodium acetate-sodium acetate buffer having a pH of 5.0) is prepared. Immediately after production, the cellulose-containing composition is diluted with a buffer solution (similar to the above) in advance (the dilution ratio is such that the absorbance of the enzyme solution below is within the calibration curve obtained from the glucose standard solution below). To 90 μl of the substrate solution, 10 μl of the diluted evaluation slurry solution is added, and the mixture is reacted at 37 ° C. for 30 minutes. To prepare a calibration curve, select ion-exchanged water (blank) and glucose standard solution (4 points of standard solution with at least different concentrations from 0.5 to 5.6 mM), prepare 100 μl each, and prepare at 37 ° C. Keep warm for 30 minutes. 300 μl of DNS color-developing solution (1.6% by mass NaOH, 1% by mass 3,5-dinitrosalicylic acid, 30% by mass, respectively, in the enzyme-containing evaluation slurry solution, calibration line blank, and glucose standard solution after the reaction. Add (potassium sodium tartrate) and boil for 5 minutes to develop color. Immediately after color development, the mixture was ice-cooled, 2 ml of ion-exchanged water was added, and the mixture was well mixed. After allowing to stand for 30 minutes, the absorbance is measured within 1 hour. For the measurement of absorbance, 200 μl is dispensed into a 96-well microwell plate, and the absorbance at 540 nm is measured using a microplate reader. A calibration curve is prepared using the absorbance and glucose concentration of each glucose standard solution minus the absorbance of the blank. The amount of glucose equivalent produced in the cellulose-containing composition is calculated by subtracting the absorbance of the blank from the absorbance of the cellulose-containing composition and then using a calibration curve. The amount of enzyme that produces 1 μmol of glucose equal amount of reducing sugar per minute is defined as 1 unit, and the EG activity is calculated from the following formula.
EG activity = Glucose equivalent production amount (μmol) of 1 ml of cellulose-containing composition obtained by diluting with a buffer solution / 30 minutes × dilution ratio

The cellulose-containing composition of the present invention may have a viscosity of 10 mPa · s or more and 11000 mPa · s or less measured under the conditions of 25 ° C. and a rotation speed of 3 rpm, where the solid content concentration of the fibrous cellulose is 0.4% by mass. The lower limit of the viscosity is preferably 100 mPa · s or more, more preferably 200 mPa · s or more, further preferably 500 mPa · s or more, and particularly preferably 1000 mPa · s or more. The upper limit of the viscosity is preferably 10,000 mPa · s or less.
It is more preferably 8000 mPa · s or less, further preferably 6500 mPa · s or less, further preferably 5000 mPa · s or less, further preferably 4000 mPa · s or less, particularly preferably 3000 mPa · s or less, and most preferably 2000 mPa · s or less.

The viscosity is adjusted to a solid content concentration of 0.4% by mass by pouring ion-exchanged water 24 hours after the production of the cellulose-containing composition, and then allowed to stand for 24 hours in an environment of 25 ° C. , B-type viscometer (No. 3 rotor, No. 2 rotor, or No. 1 rotor) (BLOOKFIELD, analog viscometer T-LVT) was rotated at 25 ° C. at a rotation speed of 3 rpm for 3 minutes. It is the viscosity measured by.

The cellulose-containing composition of the present invention has the above-mentioned structure, so that the coatability is improved. In the present invention, by adding an enzyme to the fine fibrous cellulose after defibration, the viscosity of the fine fibrous cellulose can be efficiently adjusted without relying on mechanical treatment, which makes it suitable for coating. It can be improved. Further, since the viscosity can be efficiently reduced by adding the enzyme to the fine fibrous cellulose after defibration, the amount of the enzyme to be added can be reduced. When a film is produced using the cellulose-containing composition of the present invention, the optical and mechanical properties of the film can be improved by the above-mentioned effects. It is presumed that this is because when a large amount of the enzyme is added, it is possible to suppress the deterioration of the physical properties due to the crystallization of the protein derived from the enzyme.

The form of the cellulose-containing composition is not particularly limited, and can exist in various forms such as powder, slurry, and solid. Above all, the cellulose-containing composition is preferably a slurry.

(Fibrous cellulose)
The cellulose-containing composition of the present invention has a fiber width of 1000 nm or less and has a phosphite group or a substituent derived from the phosphite group (sometimes simply referred to as a phosphite group). Also called phosphoric acid).

The content of the fine fibrous cellulose is preferably 0.5% by mass or more, more preferably 5% by mass or more, and more preferably 20% by mass or more, based on the total solid content of the cellulose-containing composition. It is even more preferably 40% by mass or more, further preferably 50% by mass or more, and most preferably 55% by mass or more. The content of the fine fibrous cellulose is preferably 95% by mass or less.

The raw material for fibrous cellulose for obtaining fine fibrous cellulose is not particularly limited, but pulp is preferable because it is easily available and inexpensive. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include broadleaf kraft pulp (LBKP), coniferous kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), and oxygen bleached craft. Examples thereof include chemical pulp such as pulp (OKP). Examples thereof include semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), mechanical pulp such as crushed wood pulp (GP) and thermomechanical pulp (TMP, BCTMP), but are not particularly limited. Examples of the non-wood pulp include cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, cellulose isolated from sea squirts and seaweed, chitin, chitosan and the like, but are not particularly limited. .. Examples of the deinked pulp include deinked pulp made from recycled paper, but the pulp is not particularly limited. As the pulp of this embodiment, one of the above may be used alone, or two or more of them may be mixed and used. Among the above pulps, wood pulp containing cellulose and deinked pulp are preferable in terms of availability. Among wood pulps, chemical pulp has a large cellulose ratio, so the yield of fine fibrous cellulose during fiber finening (defibration) is high, the decomposition of cellulose in the pulp is small, and the fineness of long fibers with a large axial ratio It is preferable in that fibrous cellulose can be obtained. Of these, kraft pulp and sulfite pulp are most preferably selected. A film containing fine fibrous cellulose of long fibers having a large axial ratio tends to obtain high strength.

The average fiber width of the fine fibrous cellulose is 1000 nm or less as observed with an electron microscope. The average fiber width is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and less than 1000 nm, more preferably 2 nm or more and 100 nm or less, more preferably 2 nm or more and 50 nm or less, and further preferably 2 nm or more and 10 nm or less. , Not particularly limited. When the average fiber width of the fine fibrous cellulose is less than 2 nm, it is dissolved in water as a cellulose molecule, so that the physical properties (strength, rigidity, dimensional stability) of the fine fibrous cellulose tend to be difficult to develop. .. The fine fibrous cellulose is, for example, a single fibrous cellulose having a fiber width of 1000 nm or less.

The fiber width is measured by observing the fine fibrous cellulose with an electron microscope as follows. An aqueous suspension of fine fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less was prepared, and this suspension was cast onto a hydrophilized carbon film-coated grid to form a sample for TEM observation. do. If it contains wide fibers, an SEM image of the surface cast on the glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, or 50,000 times depending on the width of the constituent fibers. However, the sample, observation conditions and magnification should be adjusted so as to satisfy the following conditions.

(1) A straight line X is drawn at an arbitrary position in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y that intersects the straight line perpendicularly is drawn in the same image, and 20 or more fibers intersect the straight line Y.

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

The fiber length of the fine fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and particularly preferably 0.1 μm or more and 600 μm or less. By setting the fiber length within the above range, the destruction of the crystal region of the fine fibrous cellulose can be suppressed, and the slurry viscosity of the fine fibrous cellulose can be set within an appropriate range. The fiber length of the fine fibrous cellulose can be obtained by image analysis by TEM, SEM, or AFM.

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

The fine fibrous cellulose preferably has a phosphorous acid group or a substituent derived from the phosphorous acid group. The substituent derived from the phosphorous acid group may be a salt of the phosphorous acid group.

In the present invention, the phosphorous acid group or the substituent derived from the phosphorous acid group is, for example, a substituent represented by the following formula (2).

In equation (2), b is a natural number, m is an arbitrary number, and b × m = 1. α is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, and an unsaturated-branched chain hydrocarbon group. , An unsaturated-cyclic hydrocarbon group, an aromatic group, or an inducing group thereof. Above all, it is particularly preferable that α is a hydrogen atom. The α in the formula (2) does not include a group derived from the cellulose molecular chain.

Examples of the saturated-linear hydrocarbon group represented by α in the formula (2) include a methyl group, an ethyl group, an n-propyl group, an n-butyl group and the like, but are not particularly limited. Examples of the saturated-branched chain hydrocarbon group include an i-propyl group and a t-butyl group, but the group is not particularly limited. Examples of the saturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentyl group, a cyclohexyl group and the like. Examples of the unsaturated-linear hydrocarbon group include, but are not limited to, a vinyl group, an allyl group and the like. Examples of the unsaturated-branched chain hydrocarbon group include an i-propenyl group and a 3-butenyl group, but the group is not particularly limited. Examples of the unsaturated-cyclic hydrocarbon group include, but are not limited to, a cyclopentenyl group, a cyclohexenyl group and the like. Examples of the aromatic group include, but are not limited to, a phenyl group, a naphthyl group and the like.

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

Β ^{b +} in the formula (2) is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher cations composed of organic substances include aliphatic ammonium or aromatic ammonium, and examples of monovalent or higher valent cations composed of inorganic substances include ions of alkali metals such as sodium, potassium, and lithium. Examples thereof include cations of divalent metals such as calcium and magnesium, hydrogen ions and the like, but the present invention is not particularly limited. These may be applied alone or in combination of two or more. The monovalent or higher cation composed of an organic substance or an inorganic substance is preferably sodium or potassium ion which is hard to yellow when the fiber raw material containing β is heated and is easily industrially used, but is not particularly limited.

The fine fibrous cellulose may have a phosphoric acid group or a group derived from the phosphoric acid group in addition to the phosphite group or the substituent derived from the phosphite group. The phosphate group or the group derived from the phosphoric acid group is, for example, a substituent represented by the following formula (1) or (3). The phosphoric acid group or the group derived from the phosphoric acid group may be a condensed phosphorus oxo acid group as represented by the following formula (3).

式（１）中、ａ及びｂは自然数であり、ｍは任意の数である（ただし、ａ＝ｂ×ｍである）。α及びα’のうちａ個がＯ^-であり、残りはＯＲである。ここで、Ｒは、水素原子、飽和－直鎖状炭化水素基、飽和－分岐鎖状炭化水素基、飽和－環状炭化水素基、不飽和－直鎖状炭化水素基、不飽和－分岐鎖状炭化水素基、不飽和－環状炭化水素基、芳香族基、またはこれらの誘導基である。なお、式（１）におけるαは、セルロース分子鎖に由来する基であってもよい。

In the formula (1), a and b are natural numbers, and m is an arbitrary number (where a = b × m). Of α and α', a are O- ^and the rest are OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, or an unsaturated-branched chain. Hydrocarbon groups, unsaturated-cyclic hydrocarbon groups, aromatic groups, or inducing groups thereof. In addition, α in the formula (1) may be a group derived from a cellulose molecular chain.

In the formula (3), a and b are natural numbers, m is an arbitrary number, and n is a natural number of 2 or more (where a = b × m). Of α ¹ , α ² , ..., α ⁿ and α', a are O ^- and the rest are either R or OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, or an unsaturated-branched chain. Hydrocarbon groups, unsaturated-cyclic hydrocarbon groups, aromatic groups, or inducing groups thereof. In addition, α in the formula (3) may be a group derived from a cellulose molecular chain.

The specific examples of each group in the formulas (1) and (3) are the same as the specific examples of each group in the formula (2). Further, the specific examples of β b + in the formulas (1) and (3) are the same as the specific examples of β ^{b + in} the formula (2).

The fact that the fine fibrous cellulose has a phosphite group as a substituent means that the infrared absorption spectrum of the dispersion containing the fine fibrous cellulose is measured, and the phosphite is a metamorphic form of the phosphite group in the vicinity of 1210 cm ^-1 . It can be confirmed by observing the absorption of a certain phosphonate group based on P = O. In addition, the fact that the fibrous cellulose has a phosphoric acid group as a substituent means that the infrared absorption spectrum of the dispersion containing the fibrous cellulose is measured, and the absorption of the phosphoric acid group based on P = O is performed in the vicinity of 1230 cm ^-1 . It can be confirmed by observing. Further, the fact that fibrous cellulose has a phosphite group or a phosphate group as a substituent can be confirmed by a method of confirming a chemical shift by using NMR, a method of combining titration with element analysis, or the like.

<Introduction of phosphorous acid group>
For the introduction of the phosphite group, at least one selected from a compound having a phosphite group and a salt thereof (hereinafter referred to as "subphosphorylation reagent" or "compound A") is introduced into the fiber raw material containing cellulose. It can be done by reacting. Such a subphosphorylation reagent may be mixed with a dry or wet fiber raw material in the form of a powder or an aqueous solution. As another example, a powder or an aqueous solution of a subphosphorylation reagent may be added to the slurry of the fiber raw material.

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

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

The compound A used in this embodiment is at least one selected from a compound having a phosphorous acid group and a salt thereof. Examples of the compound having a phosphite group include phosphite, and examples of the phosphite include 99% phosphoric acid (phosphonic acid). Examples of the salt of the compound having a phosphite group include a lithium salt of phosphite, a sodium salt, a potassium salt, an ammonium salt and the like, and these can have various degrees of neutralization. Of these, phosphite and phosphite are highly efficient in introducing a phosphorus oxo acid group, are more likely to improve defibration efficiency in the defibration step described later, are low in cost, and are easy to apply industrially. Sodium salts of acids, potassium salts of phosphite, or ammonium salts of phosphite are preferably used.

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

The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material (absolute dry mass) is 0.5% by mass or more and 100% by mass. The following is preferable, 1% by mass or more and 50% by mass or less is more preferable, and 2% by mass or more and 30% by mass or less is most preferable. When the amount of phosphorus atom added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. Further, by setting the addition amount of the phosphorus atom to the fiber raw material to 100% by mass or less, the cost of the compound A to be used can be suppressed while increasing the subphosphorylation efficiency.

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

Compound B is preferably used as an aqueous solution like compound A. Further, since the uniformity of the reaction is enhanced, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved. The amount of compound B added to the fiber raw material (absolute dry mass) is preferably 1% by mass or more and 500% by mass or less, more preferably 10% by mass or more and 400% by mass or less, and 100% by mass or more and 350% by mass or less. It is more preferably 150% by mass or more, and particularly preferably 300% by mass or less.

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

When introducing a phosphorous acid group, it is preferable to perform a heat treatment. As the heat treatment temperature, it is preferable to select a temperature at which the phosphite group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. Specifically, it is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower. In addition, equipment having various heat media can be used for the heat treatment, for example, a stirring drying device, a rotary drying device, a disk drying device, a roll type heating device, a plate type heating device, a fluidized layer drying device, and an air stream. A drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, a microwave heating device, and a high frequency drying device may be used.

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

The heating device used for the heat treatment is preferably a device that can always discharge the water retained by the slurry and the water generated by the addition reaction of the fiber such as the phosphite group to the hydroxyl group to the outside of the device system. An oven or the like is preferable. If the water in the apparatus system is constantly discharged, not only the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphate esterification, can be suppressed, but also the acid hydrolysis of the sugar chain in the fiber can be suppressed. , Fine fibers having a high axial ratio can be obtained.

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

The amount of the phobic acid group introduced is preferably 5.20 mmol / g or less, more preferably 0.1 mmol / g or more and 3.65 mmol / g or less per 1 g (mass) of fine fibrous cellulose. 0.14 mmol / g or more and 3.5 mmol / g or less are even more preferable, 0.2 mmol / g or more and 3.2 mmol / g or less are further preferable, 0.4 mmol / g or more and 3.0 mmol / g or less are particularly preferable, and most. It is preferably 0.6 mmol / g or more and 2.5 mmol / g or less. By setting the amount of the phosphorous acid group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous cellulose. Further, by setting the introduction amount of the phosphorous acid group within the above range, it is possible to leave hydrogen bonds between fine fibrous celluloses while being easy to miniaturize, which is good when used as a film. Expected to develop strength.

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

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

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

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

In addition, which of phosphite, phosphoric acid, and condensed phosphoric acid is the phosphoric acid detected when the phosphoric acid group, the condensed phosphoric acid group, or both is contained in addition to the phosphite group? As a method for distinguishing between the above, for example, a method of performing a treatment for cutting the condensed structure such as acid hydrolysis and then performing the above-mentioned titration operation, or a treatment for converting a phobic acid group into a phosphate group such as an oxidation treatment. Examples thereof include a method of performing the above-mentioned titration operation after performing the above-mentioned titration operation.

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

<Alkaline treatment>
When producing fine fibrous cellulose, an alkali treatment may be performed between the phosphorous acid group introduction step and the defibration treatment step described later. The alkaline treatment method is not particularly limited, and examples thereof include a method of immersing the phosphorous acid-introduced fiber in an alkaline solution.
The alkaline compound contained in the alkaline solution is not particularly limited, but may be an inorganic alkaline compound or an organic alkaline compound. The solvent in the alkaline solution may be either water or an organic solvent. The solvent is preferably a polar solvent (water or a polar organic solvent such as alcohol), and more preferably an aqueous solvent containing at least water.
Further, among the alkaline solutions, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution is particularly preferable because of its high versatility.

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 ° C. or higher and 80 ° C. or lower, and more preferably 10 ° C. or higher and 60 ° C. or lower.
The immersion time in the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, and more preferably 10 minutes or more and 20 minutes or less.
The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less with respect to the absolute dry mass of the phosphorous acid group-introduced fiber. It is more preferable to have.

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

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

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

The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 90 ° C. or lower. The immersion time in the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, and more preferably 10 minutes or more and 60 minutes or less. The amount of the acid solution used in the acid treatment is not particularly limited, but is preferably 100% by mass or more and 100,000% by mass or less, and 1000% by mass or more and 10,000% by mass or less, for example, with respect to the absolute dry mass of the fiber raw material. Is more preferable.

<Defibration processing>
The fibrous cellulose is defibrated in the defibrating process. In the defibration treatment step, the fibers are usually defibrated using a defibration treatment device to obtain a fine fibrous cellulose-containing slurry, but the treatment device and the treatment method are not particularly limited.
As the defibration processing device, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill and the like can be used. Alternatively, as the defibration processing device, use a wet pulverizing device such as a disc type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater. You can also. The defibrating processing device is not limited to the above. Preferred defibration treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by pulverized media and less likely to cause contamination.

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

The fine fibrous cellulose may be obtained by once concentrating and / or drying the fine fibrous cellulose-containing slurry obtained by the defibration treatment, and then performing the defibration treatment again. In this case, the method of concentration and drying is not particularly limited, and examples thereof include a method of adding a concentrating agent to a slurry containing fine fibrous cellulose, a method of using a commonly used dehydrator, a press, and a dryer. In addition, known methods such as those described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used. Further, it is also possible to concentrate and dry the fine fibrous cellulose-containing slurry by forming it into a sheet, perform a defibration treatment on the sheet, and obtain the fine fibrous cellulose-containing slurry again.

Equipment used for re-grinding (crushing) after concentrating and / or drying the fine fibrous cellulose-containing slurry includes a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, and an ultra-high pressure homogenizer. , High-pressure collision type crusher, ball mill, bead mill, disc type refiner, conical refiner, twin-screw kneader, vibration mill, homomixer under high-speed rotation, ultrasonic disperser, beater, etc. It can be done, but it is not particularly limited.

<Enzyme treatment>
The cellulose-containing composition of the present invention contains a protein, and the protein contains an enzyme.
The enzyme used in the present invention is a cellulase-based enzyme and is classified into a sugar hydrolase family based on the higher-order structure of a catalytic domain having a hydrolysis reaction function of cellulose. Cellulase-based enzymes are classified into endo-glucanase and cellobiohydrolase according to their cellulolytic properties. Endo-type glucanase is highly hydrolyzable to the amorphous portion of cellulose, soluble cellooligosaccharides, or cellulose derivatives such as carboxymethyl cellulose, and randomly cleaves their molecular chains from the inside to reduce the degree of polymerization. However, endo-type glucanase has low hydrolysis reactivity with crystalline cellulose microfibrils. In contrast, cellobiohydrolase decomposes the crystalline portion of cellulose to give cellobiose. In addition, cellobiohydrolase is hydrolyzed from the end of the cellulose molecule and is also called an exo-type or processive enzyme. In the present invention, it is preferable to use end-type glucanase.

As the enzyme used in the present invention, hemicellulase-based enzymes may be used in addition to endo-type glucanase and cellobiohydrolase. Among the hemicellulase-based enzymes, xylanase, which is an enzyme that decomposes xylan, mannase, which is an enzyme that decomposes mannan, and arabanase, which is an enzyme that decomposes alabang, can be mentioned. In addition, pectinase, which is an enzyme that decomposes pectin, can also be used as a hemicellulase-based enzyme. Microorganisms that produce hemicellulase-based enzymes often also produce cellulase-based enzymes.

Hemicellulose is a polysaccharide excluding pectins between cellulose microfibrils in plant cell walls. Hemicellulose is diverse and varies between plant types and cell wall layers. In wood, glucomannan is the main component in the secondary walls of coniferous trees, and 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwoods. Therefore, it is preferable to use mannase in order to obtain fine fibers from coniferous trees, and it is preferable to use xylanase in the case of hardwoods.

According to the present invention, an enzyme having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from a phosphite group is 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of fibrous cellulose. A method for producing a cellulose-containing composition, which comprises a step of adding the above-mentioned material is provided. By adding the enzyme to the fine fibrous cellulose, the fine fibrous cellulose can be reacted with the enzyme. In the present invention, it is possible to adopt a form in which the washing step of the fine fibrous cellulose is not performed after the enzyme treatment.
In the present invention, the enzyme may be inactivated after the enzyme treatment. As a method for inactivating the enzyme, a mixture of fine fibrous cellulose and enzyme is heated to 100 ° C. and allowed to stand for 30 minutes to 1 hour while maintaining the temperature, or a mixture of fine fibrous cellulose and enzyme. On the other hand, the pH may be adjusted to 10 or more by adding a strong base, but the pH is not particularly limited.
The cellulose-containing composition of the present invention can be produced by the above-mentioned method for producing a cellulose-containing composition.

The amount of the enzyme to be added to 1 part by mass of fibrous cellulose having a fiber width of 1000 nm or less and a phosphite group or a substituent derived from the phosphite group is 1 × 10 ^-3 parts by mass or less. It is preferably 1 × 10 ^-4 parts by mass or less, more preferably 1 × 10 ^-5 parts by mass or less, and particularly preferably 5.0 × 10 ^-6 parts by mass or less. The amount of the enzyme added is preferably 1 × 10 ^-7 parts by mass or more, more preferably 3 × 10 ^-7 parts by mass or more, and further preferably 1 × 10 ^-6 parts by mass or more with respect to 1 part by mass of fibrous cellulose. preferable.
By setting the addition amount of the enzyme within the above range, good coatability of the produced cellulose-containing composition can be achieved.

The reaction time between the fine fibrous cellulose and the enzyme is not particularly limited, but is generally preferably 1 minute to 24 hours, more preferably 1 minute to 1 hour.
The reaction temperature and reaction pH of the fine fibrous cellulose and the enzyme are preferably kept at the optimum temperature and the optimum pH of the enzyme to be used, and are generally set to 20 ° C to 80 ° C and pH 4.5 to 9.5. It is preferable to keep it.
By setting the reaction conditions within the above range, good coatability of the produced cellulose-containing composition can be achieved.

<Degree of polymerization>
In the cellulose-containing composition of the present invention, the degree of polymerization of the fibrous cellulose is not particularly limited, but is preferably 200 or more and 450 or less, more preferably 250 or more and 400 or less, and more preferably 250 or more and 350 or less. Even more preferably, it is particularly preferably 270 or more and 300 or less.

The degree of polymerization of fibrous cellulose is measured according to Tappi T230. That is, after measuring the viscosity (referred to as η1) measured by dispersing the fibrous cellulose to be measured in a dispersion medium and the blank viscosity (referred to as η0) measured only with the dispersion medium, the specific viscosity (ηsp) is unique. The viscosity ([η]) is measured according to the following formula.
ηsp = (η1 / η0) -1
[Η] = ηsp / (c (1 + 0.28 × ηsp))
Here, c in the formula indicates the concentration of fine fibrous cellulose at the time of viscosity measurement.
Further, the degree of polymerization (DP) of the fine fibrous cellulose is calculated from the following formula.
DP = 1.75 × [η] Since this degree of polymerization is the average degree of polymerization measured by the viscosity method, it is sometimes referred to as “viscosity average degree of polymerization”.

(Hydrophilic polymer)
The cellulose-containing composition of the present invention may further contain a hydrophilic polymer. In particular, when the fibrous cellulose-containing composition is a slurry for forming a coating film, it is preferable to contain a hydrophilic polymer. Since the slurry for forming a coating film contains a hydrophilic polymer, a fine fibrous cellulose-containing film having high transparency and excellent mechanical strength can be obtained.

Examples of the hydrophilic polymer include polyethylene glycol, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.), casein, dextrin, starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), and the like. Examples thereof include polyethylene oxide, polyvinylpyrrolidone, polyvinylmethyl ether, polyacrylic acid salts, polyacrylamide, acrylic acid alkyl ester copolymer, and urethane-based copolymer. Among them, the hydrophilic polymer is preferably at least one selected from polyethylene glycol (PEG), polyvinyl alcohol (PVA), modified polyvinyl alcohol (modified PVA) and polyethylene oxide (PEO), and polyethylene oxide (PEO) is preferable. ) Is more preferable.

The content of the hydrophilic polymer is preferably 0.5 parts by mass or more, more preferably 3 parts by mass or more, and 5 parts by mass or more with respect to 100 parts by mass of the fibrous cellulose. It is more preferably 10 parts by mass or more, and particularly preferably 10 parts by mass or more. The content of the hydrophilic polymer is preferably 5000 parts by mass or less, more preferably 1000 parts by mass or less, and 500 parts by mass or less with respect to 100 parts by mass of the fibrous cellulose. It is more preferably 100 parts by mass or less, and particularly preferably 100 parts by mass or less.

The viscosity average molecular weight of the hydrophilic polymer is not particularly limited, but is preferably 1.0 × 10 ³ or more and 1.0 × 10 ⁷ or less, and 2.0 × 10 ³ or more and 1.0 × 10 ⁷ or less. It is more preferable, and it is further preferable that it is 5.0 × 10 ³ or more and 1.0 × 10 ⁷ or less.

(Optional ingredient)
The fibrous cellulose-containing composition of the present invention may contain any component other than the above-mentioned components. Optional components include, for example, defoamers, lubricants, UV absorbers, dyes, pigments, stabilizers, surfactants, coupling agents, inorganic layered compounds, inorganic compounds, leveling agents, organic particles, antistatic agents. , Magnetic powder, orientation promoter, plasticizer, preservative, cross-linking agent and the like. Further, organic ions may be added as an optional component.

As an optional component, a thermoplastic resin, a thermosetting resin, a photocurable resin and the like may be added. These resins may be added as an emulsion. Specific examples of the thermosetting resin emulsion and the photocurable resin emulsion include those described in JP-A-2009-299043.

(Cellulose-containing membrane)
The present invention also relates to a cellulose-containing membrane formed from the above-mentioned cellulose-containing composition. The present invention is a cellulose-containing membrane having a fiber width of 1000 nm or less and containing a fibrous cellulose having a phosphite group or a substituent derived from the phosphite group and a protein, wherein the protein contains an enzyme. It relates to a cellulose-containing membrane having a protein content of 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of the fibrous cellulose. In the specification of the present application, the film includes a film laminated on another substrate, a sheet peeled off from the substrate, and the like.

The protein content in the cellulose-containing membrane may be 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of fibrous cellulose, preferably 1 × 10 ^-4 parts by mass or less, and 1 × 10 ^-5 parts by mass. The following is more preferable, and 5.0 × 10 ^-6 parts by mass or less is particularly preferable. The protein content in the cellulose-containing membrane is preferably 1 × 10 ^-7 parts by mass or more, more preferably 3 × 10 ^-7 parts by mass or more, and 1 × 10 ^-6 parts by mass or more with respect to 1 part by mass of fibrous cellulose. Is more preferable.
The protein content in the cellulose-containing membrane can be controlled by adjusting the addition amount of the enzyme, adjusting the production process of the fine fibrous cellulose including the enzyme treatment, and the like. In the present embodiment, the amount of protein in the cellulose-containing membrane can be adjusted, for example, due to the timing of performing the enzyme treatment, the fact that the washing step is not included after the enzyme treatment and before the membrane forming step, and the like. By setting the protein content in the cellulose-containing membrane to 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of fibrous cellulose, the optical properties of the cellulose-containing membrane can be improved.

The haze of the cellulose-containing film of the present invention is preferably less than 2.0%, more preferably less than 1.5%, and even more preferably less than 1.0%. The haze of the cellulose-containing film is a value measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7136.

The tensile elastic modulus of the cellulose-containing film of the present invention is preferably 1 GPa or more, more preferably 2 GPa or more, and further preferably 4 GPa or more. The upper limit of the tensile elastic modulus of the cellulose-containing film is not particularly limited, but may be, for example, 50 GPa or less. The tensile elastic modulus of the cellulose-containing film is a value measured using a tensile tester Tensilon (manufactured by A & D Co., Ltd.) in accordance with JIS P 8113. When measuring the tensile elastic modulus, a test piece prepared at 23 ° C. and 50% relative humidity for 24 hours is used as a test piece for measurement, and the measurement is performed under the conditions of 23 ° C. and 50% relative humidity.

The thickness of the cellulose-containing film of the present invention is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. The upper limit of the thickness of the cellulose-containing film is not particularly limited, but may be, for example, 1000 μm or less. The thickness of the cellulose-containing film can be measured with a stylus type thickness gauge (Millitron 1202D manufactured by Marl Co., Ltd.).

The basis weight of the cellulose-containing film of the present invention is preferably 10 g / m ² or more, more preferably 20 g / m ² or more, and even more preferably 30 g / m ² or more. The basis weight of the cellulose-containing film is preferably 100 g / m ² or less, and more preferably 80 g / m ² or less. Here, the basis weight of the cellulose-containing film can be calculated in accordance with JIS P 8124.

(Membrane formation method)
The step of forming the cellulose-containing film is a step of obtaining a slurry containing a fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from the phosphite group and a protein, and a step of obtaining this slurry. It includes a step of coating on a base material or a step of making a slurry.

In the step of obtaining the slurry, an enzyme of 1 × 10 ^-3 parts by mass or less may be added to 1 part by mass of the fine fibrous cellulose contained in the slurry.

In the step of obtaining the slurry, it is preferable to further add a hydrophilic polymer. Further, in addition to the hydrophilic polymer, a thermoplastic resin such as polyamine polyamide epihalohydrin, a polyester resin, an acrylic resin, or a urethane resin may be added. By adding a hydrophilic polymer or the like in this way, a cellulose-containing film having excellent transparency and mechanical strength can be formed. When a hydrophilic polymer or the like is added, the hydrophilic polymer or the like may be added before the enzyme is added to the fine fibrous cellulose.

<Coating process>
The coating step is a step of coating the slurry obtained in the step of obtaining the slurry on the substrate and drying the slurry to form a film. The formed cellulose-containing film may be used without peeling from the base material, or may be used as a single sheet by peeling from the base material. By using a coating device and a long base material, a cellulose-containing film can be continuously produced.

The material of the base material used in the coating process is not particularly limited, but a material having high wettability to the composition (slurry) may suppress shrinkage of the cellulose-containing film during drying, but contains cellulose. When the film is peeled off from the substrate and used, it is preferable to select one in which the cellulose-containing film formed after drying can be easily peeled off. Of these, a resin film or plate or a metal film or plate is preferable, but is not particularly limited. For example, resin films and plates such as acrylic, polyethylene terephthalate, vinyl chloride, polystyrene, and polyvinylidene chloride, metal films and plates of aluminum, zinc, copper, and iron plates, and those whose surfaces are oxidized, stainless films. And boards, brass films and boards can be used.

In the coating process, when the viscosity of the slurry is low and it develops on the substrate, a dammed frame is fixed on the substrate to obtain a cellulose-containing film of a predetermined thickness and basis weight. You may. The quality of the dammed frame is not particularly limited, but it is preferable to select one in which the end portion of the cellulose-containing film attached after drying can be easily peeled off. Of these, those obtained by molding a resin plate or a metal plate are preferable, but are not particularly limited. For example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates and polyvinylidene chloride plates, metal plates such as aluminum plates, zinc plates, copper plates and iron plates, and those whose surfaces are oxidized, stainless steel. A molded plate, brass plate, or the like can be used.

As the coating machine for coating the slurry, for example, a roll coater, a gravure coater, a die coater, a curtain coater, an air doctor coater and the like can be used. A die coater, a curtain coater, and a spray coater are preferable because the thickness can be made more uniform.

The coating temperature is not particularly limited, but is preferably 20 ° C. or higher and 45 ° C. or lower, more preferably 25 ° C. or higher and 40 ° C. or lower, and further preferably 27 ° C. or higher and 35 ° C. or lower. When the coating temperature is at least the above lower limit value, the slurry can be easily coated, and when it is at least the above upper limit value, volatilization of the dispersion medium during coating can be suppressed.

In the coating step, it is preferable to coat the slurry so that the finished basis weight of the cellulose-containing film is 10 g / m ² or more and 100 g / m ² or less, preferably 20 g / m ² or more and 60 g / m ² or less. By coating so that the basis weight is within the above range, a cellulose-containing film having excellent strength can be obtained.

The coating step preferably includes a step of drying the slurry coated on the substrate. The drying method is not particularly limited, and may be either a non-contact drying method or a method of drying while restraining the cellulose-containing membrane, and these may be combined.

The non-contact drying method is not particularly limited, but a method of heating and drying with hot air, infrared rays, far infrared rays or near infrared rays (heat drying method) and a method of vacuum drying (vacuum drying method) are applied. Can be done. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Drying with infrared rays, far-infrared rays or near-infrared rays can be performed using an infrared device, a far-infrared device or a near-infrared device, but is not particularly limited. The heating temperature in the heat drying method is not particularly limited, but is preferably 20 ° C. or higher and 150 ° C. or lower, and more preferably 25 ° C. or higher and 105 ° C. or lower. When the heating temperature is at least the above lower limit value, the dispersion medium can be rapidly volatilized, and when it is at least the above upper limit value, the cost required for heating can be suppressed and the discoloration of fine fibrous cellulose can be suppressed due to heat. ..

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

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

The method for producing the cellulose-containing film from the slurry is not particularly limited, and examples thereof include a method using the production apparatus described in WO2011 / 013567. This manufacturing device discharges a slurry containing fine fibrous cellulose onto the upper surface of an endless belt, and squeezes a dispersion medium from the discharged slurry to produce a web, and a water-squeezed section that dries the web to form a fiber sheet. It has a dry section to produce. An endless belt is arranged from the watering section to the drying section, and the web generated in the watering section is conveyed to the drying section while being placed on the endless belt.

The dehydration method that can be adopted is not particularly limited, and examples thereof include a dehydration method that is normally used in paper production, and a method of dehydrating with a long net, a circular net, an inclined wire, or the like and then dehydrating with a roll press is preferable. Further, the drying method is not particularly limited, and examples thereof include methods used in the production of paper, and for example, methods such as a cylinder dryer, a Yankee dryer, hot air drying, a near infrared heater, and an infrared heater are preferable.

(Laminated body)
Another layer may be further laminated on the cellulose-containing film obtained in the above-mentioned step to form a laminated body. Such other layers may be provided on both surfaces of the cellulose-containing film, but may be provided only on one surface of the cellulose-containing film. Examples of the other layer laminated on at least one surface of the cellulose-containing film include a resin layer and an inorganic layer.

As a specific example of the laminated body, for example,
A laminate in which a resin layer is directly laminated on at least one surface of a cellulose-containing film;
A laminate in which an inorganic layer is directly laminated on at least one surface of a cellulose-containing membrane;
A laminate in which a resin layer, a cellulose-containing film, and an inorganic layer are laminated in this order;
A laminate in which a cellulose-containing film, a resin layer, and an inorganic layer are laminated in this order; and a laminate in which a cellulose-containing film, an inorganic layer, and a resin layer are laminated in this order:
Can be mentioned.
The layer structure of the laminated body is not limited to the above, and may be various modes depending on the application.

<Resin layer>
The resin layer is a layer containing a natural resin or a synthetic resin as a main component. Here, the main component refers to a component contained in an amount of 50% by mass or more with respect to the total mass of the resin layer. The content of the resin is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and 90% by mass, based on the total mass of the resin layer. The above is particularly preferable. The content of the resin may be 100% by mass or 95% by mass or less.

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

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

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

As the resin constituting the resin layer, one kind may be used alone, or a copolymer obtained by copolymerizing or graft-polymerizing a plurality of resin components may be used. Further, a plurality of resin components may be used as a blend material mixed by a physical process.

An adhesive layer may be provided between the cellulose-containing film and the resin layer, or the adhesive layer may not be provided and the cellulose-containing film and the resin layer may be in direct contact with each other. When an adhesive layer is provided between the cellulose-containing film and the resin layer, an acrylic resin can be mentioned as an adhesive constituting the adhesive layer, for example. Examples of the adhesive other than the acrylic resin include vinyl chloride resin, (meth) acrylic acid ester resin, styrene / acrylic acid ester copolymer resin, vinyl acetate resin, and vinyl acetate / (meth) acrylic acid ester. Examples include polymer resins, urethane resins, silicone resins, epoxy resins, ethylene / vinyl acetate copolymer resins, polyester resins, polyvinyl alcohol resins, ethylene vinyl alcohol copolymer resins, and rubber emulsions such as SBR and NBR. Be done.

When the adhesive layer is not provided between the cellulose-containing film and the resin layer, the resin layer may have an adhesion aid, or the surface of the resin layer may be surface-treated such as a hydrophilization treatment. good.
Examples of the adhesion aid include a compound containing at least one selected from an isocyanate group, a carbodiimide group, an epoxy group, an oxazoline group, an amino group and a silanol group, and an organic silicon compound. Among them, the adhesion aid is preferably at least one selected from a compound containing an isocyanate group (isocyanate compound) and an organosilicon compound. Examples of the organosilicon compound include a silane coupling agent condensate and a silane coupling agent.
Examples of the surface treatment method other than the hydrophilization treatment include corona treatment, plasma discharge treatment, UV irradiation treatment, electron beam irradiation treatment, flame treatment and the like.

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

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

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

(Use)
The cellulose-containing composition of the present invention can be mixed with, for example, a paint, a resin, an emulsion, a hydraulic material (cement), or rubber and used as a reinforcing material. A cellulose-containing film may be produced by forming a film using the slurry of the cellulose-containing composition of the present invention. The cellulose-containing composition of the present invention can also be used for various purposes as a thickener.

Cellulose-containing films are suitable for use in light-transmitting substrates such as various display devices, various solar cells, and the like. It is also suitable for applications such as substrates for electronic devices, materials for home appliances, window materials for various vehicles and buildings, interior materials, exterior materials, and packaging materials. Further, it is suitable for applications such as threads, filters, woven fabrics, cushioning materials, sponges, abrasives, etc., as well as applications in which the cellulose-containing film itself is used as a reinforcing material.

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

[Example 1]
<Preparation of phosphite-introduced fibrous cellulose>
As raw material pulp, Oji Paper's softwood kraft pulp (solid content 93% by mass, basis weight 208 g / m ² sheet form, Canadian standard drainage degree (CSF) measured according to JIS P 8121 by separation is 700 ml) It was used.
Subphosphorylation treatment was carried out on this raw material pulp as follows. First, a mixed aqueous solution of phosphoric acid (phosphonic acid) and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp, and 33 parts by mass of phosphoric acid (phosphonic acid), 120 parts by mass of urea, and 150 parts of water. The amount was adjusted to be parts by mass, and a chemical-impregnated pulp was obtained. Next, the obtained chemical-impregnated pulp was heated in a hot air dryer at 165 ° C. for 250 seconds to introduce a phosphite group into the cellulose in the pulp to obtain a phosphite pulp.

Then, the obtained subphosphorylated pulp was washed. In the washing treatment, the pulp dispersion obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of subphosphorylated pulp is stirred so that the pulp is uniformly dispersed, and then the operation of filtering and dehydrating is repeated. Was done by. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

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

The infrared absorption spectrum of the subphosphorylated pulp thus obtained was measured using FT-IR. As a result, absorption based on P = O of the phosphonic acid group, which is a metamorphic form of the phosphorous acid group, was observed around 1210 cm ^-1 , and the phosphorous acid group (phosphonic acid group) was added to the pulp. Was confirmed. In addition, when the obtained subphosphorylated pulp was tested and analyzed by an X-ray diffractometer, two positions were found: 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed in, and it was confirmed that it had cellulose type I crystals. The amount of phosphite group (first dissociated acid amount) measured by the measuring method described in <Measurement of phobic acid group amount> described later for the obtained subphosphorylated pulp was 1.51 mmol / g. rice field. The total amount of dissociated acid was 1.54 mmol / g.

<Defibration processing>
Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass.
This slurry was treated four times with a wet atomizer (Sugino Machine Limited, Starburst) at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion A containing fine fibrous cellulose.
By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal.
Moreover, when the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 3 to 5 nm.

<Measurement of phosphite group amount>
The amount of phosphite group in the fine fibrous cellulose is a fiber prepared by diluting the fine fibrous cellulose dispersion containing the target fine fibrous cellulose with ion-exchanged water so that the content is 0.2% by mass. The cellulose-like cellulose-containing slurry was treated with an ion-exchange resin and then titrated with an alkali for measurement.
For the treatment with the ion exchange resin, a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) with a volume of 1/10 is added to the above fibrous cellulose-containing slurry, and the mixture is shaken for 1 hour. This was done by pouring onto a mesh with an opening of 90 μm to separate the resin and the slurry.
For titration using alkali, change in pH value indicated by the slurry is measured while adding 10 μL of 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry treated with an ion exchange resin every 5 seconds. I went by doing. Titration was performed while blowing nitrogen gas into the slurry from 15 minutes before the start of titration. In this neutralization titration, two points are observed where the increment (differential value of pH with respect to the amount of alkaline drop) becomes maximum in the curve plotting the measured pH with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first when alkali is added is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 1). The amount of alkali required from the start of titration to the first end point is equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. The amount of alkali (mmol) required from the start of titration to the first end point divided by the solid content (g) in the slurry to be titrated was defined as the amount of first dissociating acid (mmol / g). The total amount of dissociated acid (mmol / g) was defined as the value obtained by dividing the amount of alkali (mmol) required from the start of titration to the second end point by the solid content (g) in the slurry to be titrated.

<Measurement of fiber width>
The fiber width of the fine fibrous cellulose was measured by the following method.
The supernatant of the fine fibrous cellulose dispersion obtained by treatment with a wet atomizing device is mixed with water so that the concentration of the fine fibrous cellulose is 0.01% by mass or more and 0.1% by mass or less. It was diluted and added dropwise to the hydrophilized carbon grid film. This was dried, stained with uranyl acetate, and observed with a transmission electron microscope (JEOL-2000EX, manufactured by JEOL Ltd.).

<Enzyme treatment>
In the fine fibrous cellulose dispersion A, an enzyme-containing liquid (manufactured by AB Enzymes, ECOPULP R, enzyme content is about 5% by mass) was added to 1 part by mass of the fine fibrous cellulose by 3.0 × 10 ^-6 mass. Partially added, and the mixture was stirred at 18,500 rpm for 2 minutes. This was recovered to obtain a slurry for evaluation.

[Example 2]
In the <enzyme treatment> of Example 1, 1.0 × 10 ⁻² parts by mass of the enzyme-containing liquid was added to 1 part by mass of the fine fibrous cellulose. Other procedures were the same as in Example 1 to obtain a slurry for evaluation.

[Example 3]
In the <enzyme treatment> of Example 1, 1.0 × 10 ^-5 parts by mass of the enzyme-containing liquid was added to 1 part by mass of the fine fibrous cellulose. Other procedures were the same as in Example 1 to obtain a slurry for evaluation.

[Example 4]
In the <enzyme treatment> of Example 1, 4.76 × 10 ^-5 parts by mass of the enzyme-containing liquid was added to 1 part by mass of the fine fibrous cellulose. Other procedures were the same as in Example 1 to obtain a slurry for evaluation.

[Comparative Example 1]
In Example 1, <enzyme treatment> was not performed. A slurry for evaluation was obtained in the same manner as in Example 1 except for the above.

[Comparative Example 2]
<Enzyme treatment>
The subphosphorylated pulp obtained in <Preparation of phobic acid group-introduced fibrous cellulose> in Example 1 after the alkali treatment and washing treatment was diluted to 2% with ion-exchanged water, and then the enzyme-containing liquid was added. rice field. The amount of the enzyme-containing liquid added was 4.76 × 10 ^-5 parts by mass with respect to 1 part by mass of the solid content. Next, the subphosphorylated pulp was allowed to stand in an environment of 25 ° C. for 24 hours, dehydrated to obtain a dehydrated sheet, and then 5000 parts by mass of ion-exchanged water was poured, and the mixture was stirred and uniformly dispersed. , Filtered and dehydrated. Then, 5000 parts by mass of ion-exchanged water was poured again, and the mixture was stirred and uniformly dispersed, and then filtered and dehydrated.

The amount of phosphite groups (strong acid group amount) measured by the above method for the phosphorylated pulp after filtration and dehydration was 1.45 mmol / g. Further, when the analysis was performed by an X-ray diffractometer, typical peaks were confirmed at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less, and cellulose type I. It was confirmed that it had crystals.

<Defibration processing>
Ion-exchanged water was added to the obtained subphosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass.
This slurry was treated four times at a pressure of 200 MPa with a wet atomizer (Sugino Machine Limited, Starburst) to obtain an evaluation slurry containing fine fibrous cellulose.
By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal.
Moreover, when the fiber width of the fine fibrous cellulose was measured by the method using the above-mentioned transmission electron microscope, it was 3 to 5 nm.

[Comparative Example 3]
The TEMPO oxidized pulp obtained through <TEMPO oxidation> described later was diluted to 2% with ion-exchanged water after alkali treatment and washing treatment, and then an enzyme-containing liquid was added. The amount of the enzyme-containing liquid added was 4.76 × 10 ^-5 parts by mass with respect to 1 part by mass of the solid content. Next, the TEMPO oxide pulp was allowed to stand in an environment of 25 ° C. for 24 hours, dehydrated to obtain a dehydrated sheet, and then 5000 parts by mass of ion-exchanged water was poured, stirred and uniformly dispersed. It was filtered and dehydrated. Then, 5000 parts by mass of ion-exchanged water was poured again, and the mixture was stirred and uniformly dispersed, and then filtered and dehydrated.

<TEMPO oxidation>
As the raw material pulp, softwood kraft pulp (undried) made by Oji Paper was used.
The raw material pulp was subjected to alkaline TEMPO oxidation treatment as follows.
First, the above raw pulp equivalent to 100 parts by mass of dry mass, 1.6 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl), and 10 parts by mass of sodium bromide are added to 10,000 parts by mass of water. It was dispersed in the department. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so as to be 3.8 mmol, and the reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to keep the pH at 10 or more and 10.5 or less, and the reaction was considered to be completed when no change was observed in the pH.

<Cleaning of TEMPO oxide pulp>
Then, the obtained TEMPO oxide pulp was washed.
The washing treatment is carried out by dehydrating the pulp slurry after TEMPO oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring and uniformly dispersing the pulp slurry, and then repeating the operation of filtering and dehydrating. rice field. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.
The dehydrated sheet was subjected to additional oxidation treatment of the remaining aldehyde groups as follows.

The dehydration sheet corresponding 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). Then, 113 parts by mass of 80% sodium chlorite was added, and the mixture was immediately sealed and then reacted at room temperature for 48 hours while stirring at 500 rpm using a magnetic stirrer to obtain a pulp slurry.

Then, the obtained top-oxidized TEMPO oxide pulp was washed.
The washing treatment is carried out by dehydrating the pulp slurry after additional oxidation to obtain a dehydrated sheet, pouring 5000 parts by mass of ion-exchanged water, stirring and uniformly dispersing the pulp slurry, and then repeating the operation of filtering and dehydrating. rice field. When the electrical conductivity of the filtrate became 100 μS / cm or less, the washing end point was set. With respect to the TEMPO oxide pulp thus obtained, the amount of carboxy group measured by the measuring method described later was 1.30 mmol / g.
Further, when the obtained TEMPO oxide pulp was tested and analyzed by an X-ray diffractometer, it was found at two positions, 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less. A typical peak was confirmed, and it was confirmed that it had cellulose type I crystals.

<Defibration processing>
Ion-exchanged water was added to the obtained dehydrated sheet to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated four times at a pressure of 200 MPa with a wet atomizer (Sugino Machine Limited, Starburst) to obtain an evaluation slurry containing fine fibrous cellulose. By X-ray diffraction, it was confirmed that this fine fibrous cellulose maintained the cellulose type I crystal. Moreover, when the fiber width of the fine fibrous cellulose was measured by the method using the above-mentioned transmission electron microscope, it was 3 to 5 nm.

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

[Comparative Example 4]
In Comparative Example 3, the amount of the enzyme-containing liquid added was 1.0 × 10 ^-1 by mass with respect to 1 part by mass of the solid content. A slurry for evaluation was obtained in the same manner as in Comparative Example 3 except for the above.

[Comparative Example 5]
In Example 1, 1 part by mass of the enzyme-containing liquid was added to 1 part by mass of the fine fibrous cellulose. A slurry for evaluation was obtained in the same manner as in Example 1 except for the above.

<Measurement>
Using the evaluation slurries obtained in Examples and Comparative Examples, measurements were carried out according to the following method.

[viscosity]
Twenty-four hours after the production of the evaluation slurry, ion-exchanged water was poured to prepare the solid content concentration to 0.4% by mass. Then, the mixture was allowed to stand in an environment of 25 ° C. for 24 hours, and then using a B-type viscometer (No. 3 rotor) (analog viscometer T-LVT manufactured by BLOOKFIELD) at 25 ° C. at a rotation speed of 3 rpm for 3 minutes. The viscosity was measured by rotating.

[Degree of polymerization]
The specific viscosity and degree of polymerization of the fine fibrous cellulose were measured according to Tappi T230. That is, after measuring the viscosity (referred to as η1) measured by dispersing the fine fibrous cellulose to be measured in a dispersion medium and the blank viscosity (referred to as η0) measured only with the dispersion medium, the specific viscosity (ηsp). The intrinsic viscosity ([η]) was measured according to the following formula.
ηsp = (η1 / η0) -1
[Η] = ηsp / (c (1 + 0.28 × ηsp))
Here, c in the formula indicates the concentration of fine fibrous cellulose at the time of viscosity measurement.
Further, the degree of polymerization (DP) of the fine fibrous cellulose was calculated from the following formula.
DP = 1.75 × [η]
Since this degree of polymerization is the average degree of polymerization measured by the viscosity method, it is sometimes referred to as "viscosity average degree of polymerization".

[Endoglucanase (EG) activity]
The EG activity of the evaluation slurry was measured and defined as follows.
A substrate solution of carboxymethyl cellulose (CMCNa High Viscosity: Cat No. 150561, MP Biomedicals, Inc.) at a concentration of 1% (W / V) (concentration 100 mM, containing a sodium acetate-sodium acetate buffer at pH 5.0) was prepared. Immediately after production, the evaluation slurry was diluted with a buffer solution (similar to the above) in advance (the dilution ratio was such that the absorbance of the enzyme solution below was within the calibration curve obtained from the glucose standard solution below). To 90 μl of the substrate solution, 10 μl of the diluted evaluation slurry solution was added, and the mixture was reacted at 37 ° C. for 30 minutes.

To prepare a calibration curve, select ion-exchanged water (blank) and glucose standard solution (4 points of standard solution with at least different concentrations from 0.5 to 5.6 mM), prepare 100 μl each, and prepare at 37 ° C. It was kept warm for 30 minutes.
300 μl of DNS color-developing solution (1.6% by mass NaOH, 1% by mass 3,5-dinitrosalicylic acid, 30% by mass, respectively, in the enzyme-containing evaluation slurry solution, calibration line blank, and glucose standard solution after the reaction. (Potassium tartrate sodium) was added and boiled for 5 minutes to develop color. Immediately after color development, the mixture was ice-cooled, 2 ml of ion-exchanged water was added, and the mixture was well mixed. After allowing to stand for 30 minutes, the absorbance was measured within 1 hour.

For the measurement of the absorbance, 200 μl was dispensed into a 96-well microwell plate (269620, manufactured by NUNC), and the absorbance at 540 nm was measured using a microplate reader (infiniteM200, manufactured by TECAN).

A calibration curve was prepared using the absorbance and glucose concentration of each glucose standard solution minus the absorbance of the blank. The amount of glucose equivalent produced in the evaluation slurry solution was calculated by subtracting the blank absorbance from the absorbance of the evaluation slurry solution and then using a calibration curve (if the absorbance of the evaluation slurry solution does not enter the calibration curve, the buffer solution is described above. Remeasure by changing the dilution ratio when diluting the evaluation slurry in.) The amount of enzyme that produces 1 μmol of glucose equal amount of reducing sugar per minute was defined as 1 unit, and the EG activity was calculated from the following formula.
EG activity = Glucose equivalent production amount (μmol) / 30 minutes x dilution ratio of 1 ml of evaluation sample solution obtained by diluting with buffer solution [Fukui Sakuzo, "Biochemical experimental method (quantification method of reduced sugar) 2nd edition"", Society Publishing Center, p23-24 (1990)]

The same measurement was performed 24 hours after the evaluation slurry was produced.
In all the examples, the EG activity did not change between the evaluation slurry immediately after the addition of the enzyme and the evaluation slurry 24 hours after the evaluation slurry was produced.

[Protein content]
The protein contained in the evaluation slurry was determined by the burette method.
Pure water was added to bovine serum albumin to prepare the protein so that the mass% of the protein was 5.0% or less.
To the bovine serum albumin solution prepared above, 4 times the amount of the burette drug was added, mixed well, and left in an environment of 20 ° C to 25 ° C for 30 minutes. Then, the absorption wavelength of 540 nm was measured using a spectrophotometer. A calibration curve was drawn based on the measured values.
Next, the evaluation slurry was separated, 4 times the amount of the burette reagent was added, mixed well, and left in an environment of 20 ° C to 25 ° C for 30 minutes. Then, the absorption wavelength of 540 nm was measured using a spectrophotometer. The measured value was written on the calibration curve, and the amount of protein contained in the evaluation slurry was determined.

<Evaluation>
The evaluation slurries obtained in Examples and Comparative Examples were evaluated according to the following method.

[Optical characteristics of cellulose-containing film]
The evaluation slurry obtained in Examples and Comparative Examples was used to form a cellulose-containing film, and haze was measured. The method for forming the cellulose-containing film will be described later.
The haze was measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7136. In the evaluation results of the examples, if the haze is less than 1.0%, it is indicated as ⊚, if it is less than 1.5%, it is indicated as ○, if it is less than 2.0%, it is indicated as Δ, and if it is 2.0% or more, it is indicated as ×. ..

Method for forming a cellulose-containing film:
The concentration of the evaluation slurry was adjusted by adding ion-exchanged water so that the solid content concentration was 1.0% by mass.
Next, 100 parts by mass of a water-soluble polyester resin (manufactured by Reciprocal Chemical Co., Ltd., plus coat Z-221, solid content concentration is 20% by mass) was added to 100 parts by mass of this fine fibrous cellulose dispersion to prepare a coating composition. I got A.
Next, the coating liquid is weighed so that the finished coating film (composed of the solid content of the above coating composition A) has a finished basis weight of 50 g / m2, and the coating film is applied to a commercially available acrylic plate at 50 ° C. , Dryed in a constant temperature and humidity chamber with a relative humidity of 15%. A dammed metal frame (a gold frame having an inner size of 180 mm × 180 mm) was placed on the acrylic plate so as to have a predetermined basis weight. The coating film formed after drying was peeled off from the acrylic plate to obtain a coating film (cellulose-containing film) having a thickness of 37 μm containing fine fibrous cellulose.

[Mechanical characteristics of cellulose-containing membrane]
The tensile elastic modulus was measured using the cellulose-containing film obtained in the above [Optical properties of the cellulose-containing film].
The tensile elastic modulus was measured using a tensile tester Tensilon (manufactured by A & D Co., Ltd.) in accordance with JIS P 8113 except that the length of the test piece was 80 mm and the distance between chucks was 50 mm. When measuring the tensile elastic modulus, a test piece prepared at 23 ° C. and 50% relative humidity for 24 hours was used as a test piece, and the measurement was performed under the conditions of 23 ° C. and 50% relative humidity. In the evaluation results of the examples, ⊚ if the tensile elastic modulus is 4 GPa or more, ◯ if it is 2 GPa or more, Δ if it is 1 GPa or more, and × if it is less than 1 GPa.

[Appropriateness for coating when forming a cellulose-containing film]
To 100 parts by mass of the evaluation slurry obtained in Examples and Comparative Examples, 100 parts by mass of a water-soluble polyester resin (manufactured by Mutual Chemical Co., Ltd., Pluscoat Z-221, solid content concentration is 20% by mass) was added. A coating composition B was obtained. Next, this coating composition B was applied onto a polycarbonate film (Teijin Co., Ltd., Panlite PC-2151, thickness 300 μm) using a film applicator to form a wet film. The coating width of the film applicator was 150 mm, and the gap (coating thickness) was 3 mm. A sensory evaluation was performed on the coating suitability when coating the evaluation slurry. When visually checking the wet film, ◎ if no unevenness is seen, ○ if some unevenness is seen, △ if noticeable unevenness is seen, × if continuous wet film cannot be formed due to unevenness. Notated.

As is clear from Table 1, in Examples 1 to 4 in which the protein content and the endoglucanase activity are in a preferable range, the optical and mechanical properties of the film are good, and the coating suitability is also good. An excellent evaluation slurry was obtained.
On the other hand, as is clear from Table 2, in Comparative Example 1 to which no enzyme was added, the coating suitability was inferior. Further, in Comparative Examples 2 to 4, after the pulp was treated with the enzyme, the enzyme was washed with ion-exchanged water, but even in such a case, the protein content and the endoglucanase activity were low and the pulp was coated. The result was that the workability was inferior. Further, in Comparative Example 5 in which the protein content and the endoglucanase activity were higher than the preferable ranges, the optical properties of the membrane were poor.

Claims (7)

A cellulose-containing composition having a fiber width of 1000 nm or less, a phosphite group or a fibrous cellulose having a substituent derived from the phosphite group, and a protein, wherein the protein contains an enzyme and the protein. Content is 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of the fibrous cellulose, and the solid content concentration of the fibrous cellulose is 0.4% by mass under the conditions of 25 ° C. and 3 rpm. A cellulose-containing composition having a measured viscosity of 1000 mPa · s or more and 11000 mPa · s or less, and a degree of polymerization of the fibrous cellulose of 320 or more and 460 or less . The cellulose-containing composition according to claim 1, wherein the content of the protein is 1 × 10 ^-7 parts by mass or more with respect to 1 part by mass of the fibrous cellulose. The cellulose-containing composition according to claim 1 or 2, wherein the endoglucanase activity of the enzyme is 0.084 U / L or more and 840 U / L or less. A membrane containing a protein and a fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from the phosphite group, wherein the protein contains an enzyme and the content of the protein. However, the amount was 1 × 10 ^-3 parts by mass or less with respect to 1 part by mass of the fibrous cellulose, and the solid content concentration of the fibrous cellulose was 0.4% by mass, and the measurement was performed under the conditions of 25 ° C. and 3 rpm. A film having a viscosity of 1000 mPa · s or more and 11000 mPa · s or less and a degree of polymerization of the fibrous cellulose of 320 or more and 460 or less . The membrane according to claim 4 , wherein the content of the protein is 1 × 10 ^-7 parts by mass or more with respect to 1 part by mass of the fibrous cellulose. It includes a step of adding an enzyme of 1 × 10 ^-3 parts by mass or less to 1 part by mass of fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from the phosphite group. , A method for producing a cellulose-containing composition.
The viscosity measured under the conditions of 25 ° C. and 3 rpm with the solid content concentration of the fibrous cellulose as 0.4% by mass is 1000 mPa · s or more and 11000 mPa · s or less, and the degree of polymerization of the fibrous cellulose is 320 or more and 460. The following is a method for producing a cellulose-containing composition. Further including a defibration treatment step of reducing the fiber width of the fibrous cellulose to 1000 nm or less,
The method for producing a cellulose-containing composition according to claim 6 , wherein the step of adding the enzyme is provided after the defibration treatment step.

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