JP2021113328A - Fine fibrous cellulose inclusion - Google Patents

Abstract

To provide a fine fibrous cellulose inclusion having high transparency and suppressed yellow discoloration and a fine fibrous cellulose-containing sheet.SOLUTION: The invention relates to a fine fibrous cellulose inclusion containing fine fibrous cellulose having a phosphate group or a substituent derived from the phosphate group, wherein the fine fibrous cellulose inclusion contains a glucose unit, a value of (Cxyl+Cman+Cgal+Cara)/Cglu, where Cglu (mass%) is percentage content of the glucose unit, Cxyl (mass%) is percentage content of a xylose unit, Cman (mass%) is percentage content of a mannose unit, Cgal (mass%) is percentage content of a galactose unit and Cara (mass%) is percentage content of an arabinose unit, is 0.1 or less and content of the phosphate group or the substituent derived from the phosphate group is 0.5 mmol/g or more.SELECTED DRAWING: None

Description

The present invention relates to a fine fibrous cellulose-containing material. Specifically, the present invention relates to a fine fibrous cellulose-containing product containing a monosaccharide unit in a predetermined ratio, which is excellent in transparency and has suppressed yellowing.

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

Fibrous cellulose (pulp) is obtained by purifying lignocellulosic such as wood and herbs as a starting material. Various steaming methods are known as this purification step, and in the steaming step, components other than cellulose (for example, hemicellulose, lignin, etc.) contained in lignocellulosic are removed. As a purification step, a method such as an acidic sulfite steaming method, a method combining a pre-hydrolysis treatment method and an alkaline steaming method, and the like are known (for example, Patent Document 1).

By the way, as the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known (for example, Patent Documents 2 to 5). In the sheet or composite containing fine fibrous cellulose, the contact points between the fibers are remarkably increased, so that the tensile strength is greatly improved. Further, since the fiber width is shorter than the wavelength of visible light, the transparency is greatly improved. For example, Patent Document 2 discloses a fiber-reinforced composite material to which various functions are imparted by combining fine fibrous cellulose and a matrix material.

Fine fibrous cellulose is obtained by further defibrating the fibrous cellulose. However, since fine fibrous cellulose is a fine fiber having a fiber width of nano-order, there is a circumstance that a huge amount of energy is required in the defibration process and it is difficult to maintain the defibrated state. Therefore, by introducing a substituent on the surface of cellulose, the repulsion between fibers is strengthened and the fibers are defibrated. For example, Patent Document 3 discloses a method of obtaining oxidized cellulose while removing hemicellulose, lignin and the like by treating lignocellulosic in an aqueous solvent containing an oxidizing agent. Patent Document 4 discloses a method of obtaining oxidized cellulose by performing a pre-hydrolysis treatment step and kraft cooking and then treating with an oxidizing agent. Further, Patent Document 5 discloses a method for introducing a phosphoric acid group into the surface of cellulose.

Japanese Unexamined Patent Publication No. 2013-227705 Japanese Unexamined Patent Publication No. 2008-24788 Japanese Unexamined Patent Publication No. 2008-308802 International Publication WO2013 / 047218 Japanese Unexamined Patent Publication No. 2015-98526

As described above, fine fibrous cellulose can be easily and stably obtained by introducing a substituent on the surface of cellulose. However, it is clear from the studies by the present inventors that the fine fibrous cellulose obtained by the prior art may cause yellowing after aging or during heat treatment, and the transparency of the obtained slurry or the like may decrease. It became. Even when the substituent is eliminated after the defibration treatment as described in Patent Document 5, the suppression of yellowing and the improvement of transparency may not be sufficient, and further improvement is required. Was there.

Therefore, in order to solve the problems of the prior art, the present inventors have a fine fibrous cellulose-containing material having high transparency, which is a fine fibrous cellulose-containing material in which yellowing is suppressed, and fine particles. The study was carried out for the purpose of providing a fibrous cellulose-containing sheet.

As a result of diligent studies to solve the above problems, the present inventors have found that, among the fine fibrous cellulose-containing products containing fine fibrous cellulose having a predetermined amount or more of phosphate groups, the fine fibrous cellulose-containing product. It has been found that high transparency can be maintained and the occurrence of yellowing can be suppressed even after heat treatment by adjusting the monosaccharide unit contained in the above to a predetermined ratio.
Specifically, the present invention has the following configuration.

[1] A fine fibrous cellulose-containing substance containing fine fibrous cellulose having a substituent derived from a phosphoric acid group or a phosphoric acid group, wherein the fine fibrous cellulose-containing substance contains a glucose unit and has a glucose unit content. C _glu (mass%), xylose unit content is C _xyl (mass%), mannose unit content is C _man (mass%), galactose unit content is C _gal (mass%), arabinose unit If the content was _{C ara (mass%),} the value of _{(C xyl + C man + C} gal + C ara) / C glu is 0.1 or less, from the phosphate group or phosphate group of the fine fibrous cellulose A fine fibrous cellulose-containing product having a content of a substituent of 0.5 mmol / g or more.
[2] The fine fibrous cellulose-containing material according to [1], which has a haze of 25% or less.
[3] The fine fibrous cellulose-containing material according to [1] or [2], which has a total light transmittance of 87% or more.
[4] A fine fibrous cellulose-containing sheet formed from the fine fibrous cellulose-containing material according to any one of [1] to [3].
[5] The fine fibrous cellulose-containing sheet according to [4], which has a YI value of 1.4 or less.
[6] The description in [4] or [5], wherein the absolute value (ΔYI value) of the amount of change in the YI value before and after the fine fibrous cellulose-containing sheet is allowed to stand under a vacuum condition of 200 ° C. for 4 hours is 30 or less. Fine fibrous cellulose-containing sheet.
[7] The fine fibrous cellulose-containing sheet according to any one of [4] to [6], which has a haze of 25% or less.
[8] The fine fibrous cellulose-containing sheet according to any one of [4] to [7], which has a total light transmittance of 87% or more.

According to the present invention, it is possible to obtain a fine fibrous cellulose-containing product having high transparency and in which yellowing is suppressed. Further, in the present invention, it is possible to obtain a fine fibrous cellulose-containing sheet having high transparency and suppressed yellowing.

FIG. 1 is a graph showing the relationship between the amount of NaOH added to the fiber raw material and the electrical conductivity.

Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In the specification of the present application, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
Further, the value regarding the mass of fibers such as cellulose is based on the absolute dry mass (solid content) unless otherwise specified. “A and / or B” refers to at least one of A and B, unless otherwise stated, and may be A alone, B alone, or both A and B. It means that it may be.

(Fine fibrous cellulose-containing material)
The present invention relates to a fine fibrous cellulose-containing material containing a phosphoric acid group or a fine fibrous cellulose having a substituent derived from a phosphoric acid group. The fine fibrous cellulose-containing material of the present invention contains glucose units. Here, the glucose unit content is C _gl (mass%), the xylose unit content is C _xyl (mass%), the mannose unit content is C _man (mass%), and the galactose unit content is C _gal. (wt%), if the content of arabinose units was _{C ara (mass%),} the value of _{(C xyl + C man + C} gal + C ara) / C glu is 0.1 or less. The content of the phosphoric acid group of the fine fibrous cellulose or the substituent derived from the phosphoric acid group is 0.5 mmol / g or more.

Since the fine fibrous cellulose-containing material of the present invention has the above-mentioned structure, it has high transparency. Here, having high transparency means that the fine fibrous cellulose-containing material has a high total light transmittance and a low haze.
The fine fibrous cellulose-containing material of the present invention is also characterized in that it has a low yellowness. Further, the fine fibrous cellulose-containing material of the present invention has a low yellowness even after aging or after heat treatment, and has little yellowing. In the specification of the present application, yellowing mainly means turning yellow, but yellowing also includes turning brown, dark brown, or black.

The fine fibrous cellulose-containing material contains a phosphoric acid group or a fine fibrous cellulose having a substituent derived from a phosphoric acid group. The fine fibrous cellulose-containing substance may be a liquid substance such as a slurry, or may be a solid substance such as a powdery granular substance or a gel-like substance.

The fine fibrous cellulose has (A) a phosphoric acid group or a substituent derived from the phosphoric acid group. The phosphoric acid group is a divalent functional group obtained by removing the hydroxyl group from phosphoric acid. Specifically, it is a group represented by _{−PO 3} H _2. Substituents derived from phosphate groups include substituents such as polycondensation groups of phosphate groups, salts of phosphate groups, and phosphate ester groups. Further, in the specification of the present application, the phosphate group or the substituent derived from the phosphoric acid group may be a nonionic substituent or an ionic substituent represented by the following formula (1). ..

In equation (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (an integer of n = 1 to n) and α'are independent of each other. Represents R or OR. R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group. , Aromatic groups, or inducing groups thereof; β is a monovalent or higher cation consisting of an organic or inorganic substance.

The fine fibrous cellulose-containing material contains glucose units. Here, for example, the glucose unit is represented by the following formula (2).

In formula (2), R, R'and R "are independently hydrogen atoms, saturated-linear hydrocarbon groups, saturated-branched chain hydrocarbon groups, saturated-cyclic hydrocarbon groups, unsaturated-. A linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group, an aromatic group, or an inducing group thereof.

The fine fibrous cellulose-containing material may contain a glucose unit not derived from cellulose, but the glucose unit contained in the fine fibrous cellulose-containing material is preferably a cellulose-derived glucose unit.

The fine fibrous cellulose-containing material may be completely free of xylose units, mannose units, galactose units and arabinose units, but may contain at least one selected from xylose units, mannose units, galactose units and arabinose units. .. The xylose unit, mannose unit, galactose unit and arabinose unit are also defined in the same manner as the glucose unit described above.
If the fine fibrous cellulose-containing material contains at least one selected from xylose units, mannose units, galactose units and arabinose units, the xylose units, mannose units, galactose units and arabinose units shall be hemicellulose-derived units. Is preferable.

In the present invention, the content of glucose units _{C glu} (mass%), the content of xylose units _{C xyl} (mass%), the content of the mannose units _{C man} (mass%), the content of galactose units C _gal (wt%), if the content of arabinose units was _{C ara (mass%),} the value of _{(C xyl + C man + C} gal + C ara) / C glu is 0.1 or less. The value of _{(C xyl + C man + C} gal + C ara) / C glu is preferably 0.075 or less, more preferably 0.05 or less, still more preferably 0.04 or less, 0 It is particularly preferable that it is 0.03 or less. By the value of _{(C xyl + C man + C} gal + C ara) / C glu in the above range, it is possible to improve the transparency of the fine fibrous cellulose-containing material, further yellowing fine fibrous cellulose-containing material Can be suppressed. The lower limit of (C _xyl + C _man + C _gal + C _ara ) / C _glu is not particularly limited, but can be, for example, 0.01.

Content _{C glu} glucose units, content _{C xyl} xylose units, content _{C man} mannose units, content _{C gal} galactose units, content _{C ara} arabinose units, hydrolysis a fine fibrous cellulose to monosaccharide After decomposition, it can be measured by ion chromatography. Specifically, 200 mg of fine fibrous cellulose is collected in absolute dry mass, and 7.5 ml of 72% sulfuric acid is added thereto. Then, it is placed in a shaking constant temperature bath, and shaken and stirred at 30 ° C. and 160 rpm for 60 minutes to perform the first hydrolysis. Next, 30 μl of the first hydrolyzed pulp dispersion is placed in a 1.5 ml tube containing 840 μl of ultrapure water, and the mixture is stirred to dilute to a sulfuric acid concentration of 4%. Then, it is treated in an autoclave at 121 ° C. for 1 hour to perform a second hydrolysis treatment. Thereafter, the column (Dionex Co., CarboPac PA1) Ion chromatography (Dionex Corp., ICS-5000) equipped with a with a content of _{C glu} glucose units, content _{C xyl} xylose units, containing mannose units rate _{C man,} galactose unit content _{C gal,} quantifying the content of _{C ara} arabinose units. In the present invention, the content of each unit is calculated with the total of glucose unit, xylose unit, mannose unit, galactose unit and arabinose unit as 100% by mass.
In the analysis by ion chromatography, the flow rate is set to 1 ml / min and the column temperature is set to room temperature. Water is used as the mobile phase, and a 0.3N sodium hydroxide aqueous solution, a 0.1N potassium hydroxide aqueous solution, and a 0.25N sodium carbonate aqueous solution are used as the cleaning liquid. In the analysis, arabinose, galactose, glucose, xylose, and mannose are separated and eluted in this order. The detected peak is analyzed using analysis software (PeekNet) manufactured by Dionex.
Regarding the content of each monosaccharide unit, the value measured by hydrolyzing the fine fibrous cellulose obtained after defibration is equivalent to the value measured by hydrolyzing the pulp raw material immediately before defibration.

In the present invention, the content of the phosphoric acid group of the fine fibrous cellulose or the substituent derived from the phosphoric acid group is 0.5 mmol / g or more. The content of the phosphoric acid group or the substituent derived from the phosphoric acid group is preferably 0.6 mmol / g or more, more preferably 0.7 mmol / g or more, and more preferably 0.8 mmol / g or more. Is more preferable, and 0.9 mmol / g or more is particularly preferable. That is, the fine fibrous cellulose used in the present invention means that a phosphoric acid group or a substituent derived from a phosphoric acid group is introduced in a predetermined amount or more, and these groups are not eliminated.
As described above, the fine fibrous cellulose used in the present invention has a phosphoric acid group or a substituent derived from the phosphoric acid group in a predetermined amount or more, whereby the fine fibrous cellulose in the fine fibrous cellulose-containing material can be used. Dispersibility is improved. Further, when the fine fibrous cellulose has a phosphoric acid group of a predetermined amount or more or a substituent derived from the phosphoric acid group, the transparency of the fine fibrous cellulose-containing material can be improved more effectively, and the fineness can be further improved. It is possible to suppress the yellowing of the fibrous cellulose-containing material.

When the fine fibrous cellulose-containing material is a liquid substance, the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing material is 0.1 to 5.0 with respect to the total mass of the fine fibrous cellulose-containing material. It is preferably mass%, more preferably 0.3 to 3.0 mass%, and even more preferably 0.5 to 3.0 mass%. By setting the content of the fine fibrous cellulose in the above range, the characteristics of the fine fibrous cellulose can be easily exhibited.

When the fine fibrous cellulose-containing material is a solid substance or a gel-like substance, the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing material is 5% by mass with respect to the total mass of the fine fibrous cellulose-containing material. It is preferably more than%, more preferably 10% by mass or more, further preferably 15% by mass or more, and particularly preferably 20% by mass or more. When the fine fibrous cellulose-containing material is a solid substance or a gel-like substance, the upper limit of the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing material is not particularly limited, but is, for example, 99.5. It can be% by mass. By setting the content of the fine fibrous cellulose in the above range, a fine fibrous cellulose-containing material having better handleability can be obtained.

When a dispersion having a solid content concentration of fine fibrous cellulose of 0.2% by mass (hereinafter, also referred to as a slurry containing fine fibrous cellulose) is used, the total light transmittance of the dispersion is 87% or more. It is preferably 90% or more, and more preferably 90% or more. The upper limit of the total light transmittance of the dispersion liquid is not particularly limited, but may be, for example, 100% or 99.8%. The total light transmittance of the fine fibrous cellulose-containing slurry is diluted with ion-exchanged water so that the solid content concentration in the slurry is 0.2% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). Then, in accordance with JIS K 7361, the measurement is performed using a haze meter (HM-150 manufactured by Murakami Color Technology Research Institute). In the measurement, calibration is performed with a glass cell filled with ion-exchanged water.

The haze of the fine fibrous cellulose-containing slurry having a solid content concentration of fine fibrous cellulose of 0.2% by mass is preferably 25% or less, more preferably 20% or less, and 10% or less. Is more preferable, and 5% or less is particularly preferable. The lower limit of the haze of the fine fibrous cellulose-containing slurry is not particularly limited, but may be, for example, 0% or 0.5%.
The haze of the fine fibrous cellulose-containing sheet is diluted with ion-exchanged water so that the solid content concentration in the slurry is 0.2% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). , JIS K 7163, and measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute). In the measurement, calibration is performed with a glass cell filled with ion-exchanged water.

<Other ingredients>
The fine fibrous cellulose-containing material may contain other components in addition to the fine fibrous cellulose. Examples of other components include water-soluble polymers and surfactants. Examples of the water-soluble polymer include synthetic water-soluble polymers (for example, carboxyvinyl polymer, polyvinyl alcohol, alkyl methacrylate / acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, polyethylene glycol, diethylene glycol, triethylene glycol, polyethylene oxide, etc. Propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, polyacrylamide, etc., thickening polysaccharides (eg, xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quins Seeds, alginic acid, purulan, carrageenan, pectin, etc.), cellulose derivatives (eg, carboxymethyl cellulose, methyl cellulose, hirodoxyethyl cellulose, etc.), cationized starch, raw starch, oxidized starch, etherified starch, esterified starch, amylose, etc. Examples thereof include starches, glycerins such as glycerin, diglycerin and polyglycerin, hyaluronic acid, metal salts of hyaluronic acid and the like. Further, as the surfactant, a nonionic surfactant, an anionic surfactant, or a cationic surfactant can be used.

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

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

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

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

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

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

The fine fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous cellulose has an I-type crystal structure can be identified in the diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418 Å) monochromatic with graphite. Specifically, it can be identified from the fact that it has typical peaks at two positions near 2θ = 14 to 17 ° and 2θ = 22 to 23 °.
The ratio of the type I crystal structure to the fine fibrous cellulose is preferably 30% or more, more preferably 50% or more, still more preferably 70% or more.

The ratio of the crystal portion contained in the fine fibrous cellulose is not particularly limited in the present invention, but it is preferable to use cellulose having a crystallinity of 60% or more determined by the X-ray diffraction method. The crystallinity is preferably 65% or more, more preferably 70% or more, and in this case, further excellent performance can be expected in terms of heat resistance and low coefficient of linear thermal expansion. The crystallinity is determined by a conventional method from the X-ray diffraction profile measured and the pattern (Seagal et al., Textile Research Journal, Vol. 29, p. 786, 1959).

(Manufacturing method of fine fibrous cellulose)
Fine fibrous cellulose is obtained by defibrating a cellulose raw material. In the present invention, the cellulose raw material is subjected to prehydrolysis treatment, cooking treatment, delignin treatment, etc. before the defibration treatment, and phosphorus is obtained. It is preferable to carry out an oxidation treatment. According to the present inventor, various monosaccharides contained in the fine fibrous cellulose-containing material include pre-hydrolysis treatment, cooking treatment, delignin treatment, and the like, and appropriately adjusting these conditions. It is presumed to be important for controlling the unit to a predetermined ratio.

That is, the present invention was obtained in a pre-hydrolysis treatment step of heating a mixed solution of wood chips and water, a step of phosphorylating the fiber raw material obtained in the pre-hydrolysis treatment step, and a phosphorylation treatment step. A method for producing a fine fibrous cellulose-containing product may be used, which comprises a step of defibrating the phosphate group-containing cellulose to obtain fine fibrous cellulose. The method for producing the fine fibrous cellulose-containing material may appropriately include a cooking step, a delignin treatment step, a bleaching step, and a washing step between the pre-hydrolysis treatment step and the phosphorylation treatment step.

<Pre-hydrolysis treatment>
Prior to the pre-hydrolysis treatment step, a step of immersing the wood chips, which is a cellulose raw material, in water may be provided. By providing such a dipping step, prehydrolysis can be promoted. The immersion time is preferably 1 hour or more, and more preferably 10 hours or more.

The pre-hydrolysis treatment step is preferably a step of heating a mixed solution of wood chips and water. The heating temperature is, for example, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, further preferably 140 ° C. or higher, and particularly preferably 160 ° C. or higher. The heating time is preferably 5 minutes or longer, more preferably 10 minutes or longer, and even more preferably 20 minutes or longer. In the present invention, by providing such prehydrolysis step, it is possible to reduce the content of _{hemicellulose,} be in the value of the desired range _{(C xyl + C man + C} gal + C ara) / C glu Can be done.

In the pre-hydrolysis treatment step, the P factor is preferably 200 or more, more preferably 250 or more, and even more preferably 300 or more. The P factor is preferably 1000 or less. Here, the P factor is a guideline for expressing the total amount of heat given to the reaction system in the pre-hydrolysis treatment, and is expressed by the following formula as the product of the temperature and time during the pre-hydrolysis treatment.

In the above formula, P represents the P factor, T represents the absolute temperature (° C. + 273.5), t represents the heat treatment time, and K _{H1 (T)} / K _{100 ° C.} is the relative acid hydrolysis of the glycosidic bond. Represents speed.

The apparatus used in the pre-hydrolysis step is not particularly limited as long as it can hold the cellulose raw material in a pressurized state in a water-containing state for a desired time. For example, a general-purpose continuous cooking pot, a batch pot, or the like is used.

<Creating process / delignin process>
In the process of producing fine fibrous cellulose, a cooking step or a delignin step may be provided. The cooking step is preferably provided after the pre-hydrolysis treatment step, and is preferably provided after dehydration, dilution washing, and dehydration after the reaction of the pre-hydrolysis step is completed. In the steaming step, it is preferable to use an alkaline steaming method. As the alkaline steaming method, known steaming methods such as kraft steaming, polysulfide steaming, soda steaming, and alkaline sulfide steaming can be adopted. Above all, the kraft cooking method is preferable in consideration of pulp quality, energy efficiency and the like. For example, when wood chips are kraft-melted, the sulfide degree of the kraft cooking solution is preferably 5 to 75%, more preferably 20 to 35%. The effective alkali addition rate is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, based on the total mass of the absolute dry wood chips. The cooking temperature is preferably 140 to 170 ° C.

The apparatus used for alkaline cooking is not particularly limited. For example, a general-purpose continuous cooking pot, a batch pot, or the like is used.

In the cooking step, a cooking aid may be added to the cooking liquid to be used. Examples of the cooking aid include known cyclic keto compounds such as benzoquinone, naphthoquinone, anthraquinone, anthraquinone, phenanthroquinone and nuclear substituents such as alkyl and amino of quinone compounds, or anthrahydroquinone which is a reduced form of quinone compounds. Such hydroquinone compounds, and 9,10-diketohydroanthraquinone compounds which are stable compounds obtained as intermediates of the anthraquinone synthesis method by the Deals Alder method can be mentioned. The addition rate of the cooking aid is preferably 0.001 to 1.0% by mass with respect to the total mass of the absolute dry wood chips.

The copper value after cooking is not particularly limited, but in consideration of pulp quality and subsequent bleaching property, for example, when hardwood is used as a raw material, the copper value is preferably 6 to 13, and softwood is used as a raw material. In some cases, the copper value is preferably 20 to 35.

In the present invention, it is preferable that the unbleached pulp obtained by the above-mentioned alkaline steaming method is bleached by a known bleaching method through washing, rough selection and selection steps. Specifically, it is preferable that the lignin is first delignin by bleaching with oxygen (oxygen bleaching delignin method). Caustic soda or oxidized kraft white liquor can be used as the alkali used in the oxygen bleaching and lignin method. As the oxygen gas, oxygen from the deep cold separation method, oxygen from PSA (Pressure Swing Adsorption), oxygen from VSA (Vacum Swing Adsorption) and the like can be used. Oxygen gas and alkali are added to the pulp slurry in a mixer and mixed sufficiently, and then sent to a reaction tower capable of holding a mixture of pulp, oxygen and alkali for a certain period of time under pressure to be deligninized. The addition rate of oxygen gas is preferably 0.5 to 3% by mass, and the addition rate of alkali is preferably 0.5 to 4% by mass with respect to the total mass of the absolute dry pulp. The reaction temperature is preferably 80 to 120 ° C., the reaction time is preferably 15 to 100 minutes, and the pulp concentration is preferably 8 to 15% by mass.

In the oxygen bleaching and de-lignin step, the oxygen bleaching and de-lignin step can be continuously performed a plurality of times. Pulp that has been subjected to oxygen bleaching and lignin is preferably washed in the washing step.

Examples of the washing machine used in the washing step include a pressure diffuser, a diffusion washer, a pressure drum washer, a horizontal long net type washer, and a press washing machine. In the cleaning step, a cleaning aid such as an alkali, an acid, a chelating agent, or a surfactant can be added to the cleaning water. In addition, the washing wastewater can be reused as washing water in the washing process.

<Bleach process>
In the present invention, the unbleached pulp is preferably sent to the bleaching step through an oxygen bleaching and delignin step. In the bleaching step of the present invention, known ECF bleaching agents such as chlorine dioxide, alkali, oxygen, hydrogen peroxide and ozone can be used in combination. The above-mentioned cleaning step can be provided after each bleaching step.

During the bleaching step, a high-temperature acid treatment step, an acid cleaning step, a high-temperature chlorine dioxide bleaching step, a chelating agent treatment step with ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), or the like can be introduced. In the bleaching step, it is preferable to bleach the pulp so that the whiteness becomes 85 to 92% ISO.

In the bleaching step, it is preferable that the peroxide addition treatment is carried out under acidic conditions. In the peroxide addition treatment step, the pulp concentration is in the range of 1 to 40% by mass, preferably 8 to 15% by mass, the pH is 1 to 5, preferably 2 to 4, and the temperature is 30 to 95 ° C., preferably. It is preferably carried out at 50 to 90 ° C.

In the peroxide addition treatment step under acidic conditions, an acid can be added to bring the peroxide into an acidic state. The acid may be any of organic acids such as formic acid, oxalic acid and acetic acid, and inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, and is not particularly limited, but relatively inexpensive sulfuric acid, hydrochloric acid and the like are preferably used. .. The peroxide used in the peroxide addition treatment step under acidic conditions may be either an organic peracid or an inorganic peracid, and is not particularly limited, but is preferably relatively inexpensive and decomposes. After that, hydrogen peroxide, which has no environmental load, is preferably used. For example, when hydrogen peroxide is used, the addition rate is preferably 0.01 to 2.0% by mass, more preferably 0.1 to 1.0% by mass, based on the total mass of the absolute dry pulp. preferable.

<Phosphorylation>
In the present invention, the fine fibrous cellulose has a phosphoric acid group or a substituent derived from the phosphoric acid group (hereinafter, may be simply referred to as a phosphoric acid group).
The phosphorylation treatment can be carried out by reacting the fiber raw material obtained through the above steps with a compound having a phosphoric acid group and / or a salt thereof (hereinafter, referred to as "Compound A"). This reaction may be carried out in the presence of urea and / or a derivative thereof (hereinafter referred to as "Compound B"), whereby a phosphoric acid group can be efficiently introduced into the hydroxyl group of the fine fibrous cellulose. Can be done.

The phosphate group introduction step always includes a step of introducing a phosphate group into cellulose, and may optionally include an alkali treatment step described later, a step of washing excess reagents, and the like.

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

Compound A used in this embodiment is a compound having a phosphoric acid group and / or a salt thereof.
Examples of the compound having a phosphoric acid group include, but are not limited to, phosphoric acid, a lithium salt of phosphoric acid, a sodium salt of phosphoric acid, a potassium salt of phosphoric acid, an ammonium salt of phosphoric acid, and the like. Examples of the lithium salt of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. Examples of the sodium salt of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate. Examples of the potassium salt of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium polyphosphate and the like. Examples of the ammonium salt of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate.

Of these, from the viewpoints of high efficiency of introducing phosphoric acid groups, easy improvement of defibration efficiency in the defibration step described later, low cost, and easy industrial application, sodium phosphate and sodium phosphate A salt, a potassium salt of phosphoric acid, or an ammonium salt of phosphoric acid is preferable. Sodium dihydrogen phosphate or disodium hydrogen phosphate is more preferred.

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

The amount of compound A added to the fiber raw material is not particularly limited, but when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atom added to the fiber raw material is preferably 0.5 to 100% by mass, preferably 1 to 50% by mass. % Is more preferable, and 2 to 30% by mass is most preferable. When the amount of phosphorus atom added to the fiber raw material is within the above range, the yield of fine fibrous cellulose can be further improved. When the amount of the phosphorus atom added to the fiber raw material exceeds 100% by mass, the effect of improving the yield reaches a plateau and the cost of the compound A used increases. On the other hand, the yield can be increased by setting the addition amount of phosphorus atoms to the fiber raw material to be equal to or higher than the above lower limit value.

Examples of the compound B used in this embodiment include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, benzorainurea, and hydantin. Of these, urea is preferable because it is low in cost, easy to handle, and easy to form a hydrogen bond with a fiber raw material having a hydroxyl group.

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 is preferably 1 to 300% by mass.

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.

In the phosphoric acid group introduction step, it is preferable to perform heat treatment. The heat treatment temperature is preferably selected so that the phosphate group can be efficiently introduced while suppressing the thermal decomposition and hydrolysis reaction of the fiber. Specifically, the temperature is preferably 50 to 250 ° C, more preferably 100 to 200 ° C. Further, a vacuum dryer, an infrared heating device, and a microwave heating device may be used for heating.

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

The heating device used for the heat treatment is preferably a device capable of constantly discharging the water retained by the slurry and the water generated by the addition reaction of fibers such as phosphate groups to the hydroxyl groups to the outside of the device system. For example, a blower type oven. Etc. are 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.
The heat treatment time is preferably 1 to 300 minutes, more preferably 1 to 200 minutes after the water is substantially removed from the fiber raw material slurry, although it is affected by the heating temperature. Not limited.

Further, in the phosphoric acid group introduction step, it is highly transparent to react so that the difference in the amount of the strongly acidic group and the weakly acidic group introduced from the phosphoric acid group introduced into the cellulose is 0.5 mmol / g or less. Preferred for obtaining fine fibrous cellulose. The difference in the amount of the strongly acidic group and the weakly acidic group derived from the phosphoric acid group introduced is more preferably 0.3 mmol / g or less, and particularly preferably 0.2 mmol / g or less. preferable.

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

<Introduction amount of phosphoric acid group>
The amount of the phosphoric acid group introduced is preferably 0.1 to 3.5 mmol / g, more preferably 0.14 to 2.5 mmol / g, and 0.2 to 2 per 1 g (mass) of the fine fibrous cellulose. It is more preferably 0.0 mmol / g, more preferably 0.2 to 1.8 mmol / g, particularly preferably 0.4 to 1.8 mmol / g, and most preferably 0.6 to 1.8 mmol / g. By setting the amount of the phosphoric acid group introduced within the above range, it is possible to facilitate the miniaturization of the fiber raw material and enhance the stability of the fine fibrous cellulose. Further, by setting the amount of the phosphoric acid group introduced within the above range, the viscosity of the slurry of fine fibrous cellulose can be adjusted within an appropriate range.

The amount of the phosphoric acid group introduced into the fiber raw material can be measured by the conductivity titration method. Specifically, it is refined by a defibration treatment step, the obtained fine fibrous cellulose-containing slurry is treated with an ion exchange resin, and then the change in electrical conductivity is obtained while adding an aqueous sodium hydroxide solution. The amount introduced can be measured.

In the conductivity titration, the addition of alkali gives the curve shown in FIG. Initially, the electrical conductivity drops sharply (hereinafter referred to as the "first region"). After that, the conductivity begins to increase slightly (hereinafter referred to as "second region"). After that, the increment of conductivity increases (hereinafter referred to as "third region"). That is, three regions appear. Of these, the amount of alkali required in the first region is equal to the amount of strong acid groups in the slurry used for titration, and the amount of alkali required in the second region is equal to the amount of weakly acidic groups in the slurry used for titration. Become equal. When the phosphoric acid group causes condensation, the weakly acidic group is apparently lost, and the amount of alkali required for the second region is smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups is the same as the amount of phosphorus atoms regardless of the presence or absence of condensation. When it is said, it means the amount of strongly acidic groups.

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

The temperature of the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 to 80 ° C, more preferably 10 to 60 ° C.
The immersion time in the alkaline solution in the alkaline treatment step is not particularly limited, but is preferably 5 to 30 minutes, more preferably 10 to 20 minutes.
The amount of the alkaline solution used in the alkaline treatment is not particularly limited, but is preferably 100 to 100,000% by mass, more preferably 1,000 to 10,000% by mass, based on the absolute dry mass of the phosphate group-introduced fiber.

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

<Fiber processing>
The phosphoric acid group-introduced fiber is defibrated in the defibration treatment step. In the defibration treatment step, the fibers are usually defibrated using a defibration treatment device to obtain a fine fibrous cellulose-containing slurry, but the treatment device and the treatment method are not particularly limited.
As the defibration processing apparatus, a high-speed defibrator, a grinder (stone mill type crusher), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type crusher, a ball mill, a bead mill and the like can be used. Alternatively, as the defibration processing device, 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 should be used. You can also. The defibration processing apparatus is not limited to the above. Preferred defibration treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high-pressure homogenizer, which are less affected by crushed media and less likely to cause contamination.

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

In the present invention, the defibration treatment may be performed after the fine fibrous cellulose is concentrated and dried. In this case, the method of concentration and drying is not particularly limited, and examples thereof include a method of adding a concentrating agent to a slurry containing fine fibrous cellulose, a method of using a commonly used dehydrator, press, and dryer. In addition, known methods such as those described in WO2014 / 024876, WO2012 / 107642, and WO2013 / 121086 can be used. Further, the concentrated fine fibrous cellulose may be made into a sheet. The sheet can also be crushed for defibration treatment.

Equipment used for crushing fine fibrous cellulose includes high-speed defibrator, grinder (stone mill type crusher), high-pressure homogenizer, ultra-high pressure homogenizer, high-pressure collision type crusher, ball mill, bead mill, disc type refiner, and conical. Wet pulverizers such as refiners, twin-screw kneaders, vibration mills, homomixers under high-speed rotation, ultrasonic dispersers, beaters, etc. can also be used, but are not particularly limited.

The fine fibrous cellulose having a phosphoric acid group or a substituent derived from the phosphoric acid group obtained by the above-mentioned method is a fine fibrous cellulose-containing slurry, and can be diluted with water to a desired concentration. good. That is, the fine fibrous cellulose-containing material of the present invention may be a fine fibrous cellulose-containing slurry. In this case, the content of the fine fibrous cellulose contained in the fine fibrous cellulose-containing slurry is preferably 0.1 to 5.0% by mass with respect to the total mass of the fine fibrous cellulose-containing material. It is more preferably 3 to 3.0% by mass, and even more preferably 0.5 to 3.0% by mass.

(Sheet containing fine fibrous cellulose)
The present invention also relates to a fine fibrous cellulose-containing sheet formed from the above-mentioned fine fibrous cellulose-containing material.

The yellowness (YI value) of the fine fibrous cellulose-containing sheet of the present invention is preferably 1.4 or less, and more preferably 1.3 or less. Here, the YI value of the fine fibrous cellulose-containing sheet is a YI value (initial YI value) before heating the fine fibrous cellulose-containing sheet.

The fine fibrous cellulose-containing sheet of the present invention has less yellowing even when heat-treated. Specifically, the absolute value (ΔYI value) of the amount of change in the YI value before and after the fine fibrous cellulose-containing sheet is allowed to stand under vacuum conditions of 200 ° C. for 4 hours is preferably 30 or less, preferably 25 or less. More preferably, it is more preferably 20 or less.

The yellowness (YI value) of the fine fibrous cellulose-containing sheet before and after heating is measured according to JIS K 7373. Specifically, the measurement is performed using a colorimeter (Color Cutei manufactured by Suga Test Instruments Co., Ltd.).

The haze of the fine fibrous cellulose-containing sheet is preferably 25% or less, more preferably 20% or less, further preferably 10% or less, and particularly preferably 5% or less.
The haze of the fine fibrous cellulose-containing sheet is measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7163.

The total light transmittance of the fine fibrous cellulose-containing sheet is preferably 87% or more, and more preferably 90% or more. The total light transmittance of the fine fibrous cellulose-containing sheet is measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute) in accordance with JIS K 7361.

As described above, the fine fibrous cellulose-containing sheet of the present invention has the above physical characteristics, is excellent in transparency, and has a low yellowness. Further, even when the fine fibrous cellulose-containing sheet is heat-treated, yellowing can be suppressed.

The thickness of the fine fibrous cellulose-containing sheet is not particularly limited, but is preferably 1 to 1000 μm, more preferably 10 to 500 μm.
The basis weight of the fine fibrous cellulose-containing sheet is not particularly limited, is preferably from 10 to 100 g / ^{m 2,} and more preferably 20 to 70 g / ^{m 2.}

(Manufacturing method of fine fibrous cellulose-containing sheet)
The step of producing the fine fibrous cellulose-containing sheet includes a step of coating the above-mentioned fine fibrous cellulose-containing slurry on a base material or a step of making a paper of the fine fibrous cellulose-containing slurry.

<Coating process>
The coating step is a step of obtaining a sheet by coating a fine fibrous cellulose-containing slurry on a base material and peeling the fine fibrous cellulose-containing sheet formed by drying the slurry from the base material. By using a coating device and a long base material, sheets can be continuously produced. The quality of the base material is not particularly limited, but a material having high wettability to the fine fiber-containing slurry may suppress shrinkage of the sheet during drying, but the sheet formed after drying can be easily peeled off. It is preferable to select the one that can be used. Of these, a resin plate or a metal plate is preferable, but it is 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 plate, brass plate, etc. can be used.

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

As a coating machine for coating the fine fibrous cellulose-containing 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 to 45 ° C, more preferably 25 to 40 ° C, and even more preferably 27 to 35 ° C. When the coating temperature is at least the above lower limit value, the fine fiber-containing suspension 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.

The process for producing the fine fibrous cellulose-containing sheet preferably includes a step of drying the fine fibrous cellulose-containing slurry coated on the base material. The drying method is not particularly limited, but either a non-contact drying method or a method of drying while restraining the sheet may be used, or a combination of these may be used.

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. The heat drying method and the vacuum drying method may be combined, but the heat drying method is usually applied. Drying with infrared rays, far infrared rays or near infrared rays 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 30 to 120 ° C, more preferably 30 to 105 ° C. 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 the fine fibers due to heat can be suppressed.

After drying, the obtained fine fibrous cellulose-containing sheet is peeled off from the base material. When the base material is a sheet, the fine fibrous cellulose-containing sheet and the base material are wound while being laminated to form fine fibers. The fine fibrous cellulose-containing sheet may be peeled off from the process substrate immediately before the use of the cellulose-containing sheet.

<Papermaking process>
The step of producing the fine fibrous cellulose-containing sheet may include a step of making a paper of the fine fibrous cellulose-containing slurry. Examples of the paper machine 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-making may be performed.

In the papermaking process, the fine fibrous cellulose-containing slurry is filtered on a wire and dehydrated to obtain a wet paper sheet, which is then pressed and dried to obtain a sheet. The concentration of the slurry is not particularly limited, but is preferably 0.05 to 5% by mass. When the slurry is filtered and dehydrated, the filter cloth for filtration is not particularly limited, but it is important that the fine fibers do not pass through and the filtration rate does not become too slow. Such a filter cloth is not particularly limited, but a sheet made of an organic polymer, a woven fabric, or a porous membrane is preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE) are preferable. Specific examples thereof include a porous membrane of polytetrafluoroethylene having a pore size of 0.1 to 20 μm, for example, 1 μm, polyethylene terephthalate having a pore size of 0.1 to 20 μm, for example, 1 μm, a polyethylene woven fabric, and the like, but the present invention is not particularly limited.

The method for producing a sheet from a slurry containing fine fibers is not particularly limited, and examples thereof include a method using the production apparatus described in WO2011 / 013567. This manufacturing equipment discharges a slurry containing fine cellulose fibers 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 generate a fiber sheet. It has a drying section. An endless belt is arranged from the watering section to the drying section, and the web generated in the watering section is conveyed to the drying section while being placed on the endless belt.

The dehydration method that can be used in the present invention is not particularly limited, and examples thereof include a dehydration method that is usually used in the production of paper. Is preferable. The drying method is not particularly limited, and examples thereof include methods used in the production of paper. For example, a cylinder dryer, a yankee dryer, hot air drying, a near infrared heater, an infrared heater and the like are preferable.

(Composite sheet containing fine fibrous cellulose)
The fine fibrous cellulose-containing material may be mixed with a matrix resin or the like to form a fine fibrous cellulose-containing composite sheet. Such a composite sheet containing fine fibrous cellulose may be a sheet in which fine fibrous cellulose and a matrix resin are integrated.

The fine fibrous cellulose-containing composite sheet may be a laminate in which a sheet made of the fine fibrous cellulose-containing sheet and a matrix resin as described above are laminated. Examples of the matrix resin include a thermoplastic resin, a thermosetting resin (a cured product obtained by polymerizing and curing a precursor of a thermosetting resin by heating), or a photocurable resin (a precursor of a photocurable resin is radiation (ultraviolet rays or). Examples thereof include a cured product (cured product) which has been polymerized and cured by irradiation with an electron beam or the like.

An inorganic film may be further laminated on the surface of the fine fibrous cellulose-containing composite sheet. Examples of the inorganic material constituting the inorganic film include metals such as platinum, silver, aluminum, gold, and copper, silicone, ITO, SiO ₂ , SiN, SiOxNy, ZnO, and TFTs.

(Other forms of fine fibrous cellulose-containing material)
As described above, the fine fibrous cellulose-containing material may be a fine fibrous cellulose-containing slurry or a fine fibrous cellulose-containing powder or granule. When the fine fibrous cellulose-containing material is a fine fibrous cellulose-containing powder or granular material, the fine fibrous cellulose-containing material is composed of a powdery and / or granular substance. Here, the powdery substance means a substance smaller than the granular substance. Generally, the powdery substance refers to fine particles having a particle size of 1 nm or more and less than 0.1 mm, and the granular substance refers to particles having a particle size of 0.1 to 10 mm, but is not particularly limited. The particle size of the powder or granular material can be measured and calculated using a laser diffraction method. Specifically, it is a value measured using a laser diffraction / scattering type particle size distribution measuring device (Microtrac 3300EXII, Nikkiso Co., Ltd.).

When the fine fibrous cellulose-containing material is a fine fibrous cellulose-containing powder or granule, a known production method can be adopted as the production method. For example, an oven-drying method or a spray-drying method can be adopted.

(Use)
The use of the fine fibrous cellulose-containing material according to the present invention is not particularly limited. As an example, a film can be formed using a slurry containing fine fibrous cellulose and used as various films. As another example, the fine fibrous cellulose-containing slurry can be used as a thickener in various applications (for example, additives to foods, cosmetics, cement, paints, inks, etc.). Further, it can be mixed with a resin or an emulsion and used as a reinforcing material.

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 in a limited manner by the specific examples shown below.

<Example 1>
[Pre-hydrolysis (dehemicellulose)]
300 g of softwood chips were collected by absolute dry mass and immersed in 10 liters of tap water overnight. Then, the chips were taken out, emptied into a 400 mesh sieve, and filtered. The dehydrated chips are placed in a 2.5 liter capacity autoclave, tap water is added so that the liquid mass ratio (assuming the mass of the chips after absolute drying is 1) is 3, and then 30 at 165 ° C. It was heated for minutes and pre-hydrolyzed. The P factor at this time was 380.

[Cooking]
After pre-hydrolysis, waste gas was extracted from the degassing cock of the autoclave, and after confirming that the pressure in the autoclave became 0, the treated chips were passed through a 400 mesh sieve and filtered. The chips after filtration were placed in an autoclave having a capacity of 2.5 liters again, a cooking solution was added so that the liquid ratio was 5, and craft cooking was performed under the conditions of a cooking temperature of 165 ° C. and a cooking time of 120 minutes. The cooking solution contained 21% by mass of active alkali with respect to the absolute dry mass of the chips, and had a sulfurization degree of 28%. After cooking, the black liquor and pulp were separated, and the pulp was carefully selected on a flat screen equipped with an 8-cut screen plate to obtain pulp after cooking.

[Oxygen bleaching (degnin)]
After cooking, 70 g of pulp was collected by absolute dry mass, and 2.0 mass% of caustic soda was added to the total mass of the absolute dry pulp, and then diluted with ion-exchanged water to adjust the pulp concentration to 10 mass%. This slurry was placed in an indirect heating type autoclave, 99.9% compressed oxygen gas was injected to adjust the gauge pressure to 0.5 MPa, and oxygen exposure was performed at 100 ° C. for 60 minutes. After the oxygen exposure was completed, the pressure was reduced until the gauge pressure became 0.05 MPa or less, the pulp was taken out from the autoclave, washed with 7 liters of ion-exchanged water, and then dehydrated. In this way, pulp was obtained after oxygen exposure.

[bleaching]
After oxygen exposure, 60 g of pulp was collected by absolute dry mass, placed in a plastic bag, and the pulp concentration was adjusted to 10% by mass using ion-exchanged water. Then, 1.8% by mass of chlorine dioxide was added to the total mass of the absolute dry pulp, and the pulp was immersed in a constant temperature water bath at a temperature of 70 ° C. for 70 minutes for D0 stage treatment. The pulp obtained after the D0 step treatment was diluted to 3% by mass with ion-exchanged water, and then dehydrated and washed with a Büchner funnel. Put the pulp after the D0 stage treatment in a plastic bag, add ion-exchanged water to adjust the pulp concentration to 10% by mass, and then add 1.0% by mass of caustic soda and hydrogen peroxide to the total mass of the absolute dry pulp. It was added so as to be 0.3% by mass and mixed well. Then, the E / P stage treatment was performed by immersing in a constant temperature water tank having a temperature of 70 ° C. for 100 minutes. The obtained pulp was diluted to 3% by mass with ion-exchanged water, and then dehydrated and washed with a Büchner funnel.
The pulp after the E / P stage treatment was placed in a plastic bag, adjusted to a pulp concentration of 10% by mass using ion-exchanged water, and then 0.3% by mass of chlorine dioxide was added to the total mass of the absolute dry pulp. It was immersed in a constant temperature water tank having a temperature of 70 ° C. for 80 minutes to perform a D1 stage bleaching treatment. The obtained pulp was diluted to 3% by mass with ion-exchanged water, and then dehydrated and washed with Büchner funnel to obtain bleached pulp.

[Phosphorylation]
Bleached pulp was impregnated with a mixed aqueous solution of sodium dihydrogen phosphate dihydrate, disodium hydrogen phosphate and urea. This bleached pulp-containing aqueous solution was added to 190 parts by mass of water, 44 parts by mass of sodium dihydrogen phosphate dihydrate, 33 parts by mass of disodium hydrogen phosphate, and 160 parts by mass of urea with respect to 100 parts by mass of absolute dry mass of bleached pulp. It was squeezed so as to form a part, and a chemical-impregnated pulp was obtained. The obtained chemical-impregnated pulp was heated in a blower dryer set at 140 ° C. for 25 minutes to introduce a phosphoric acid group into the cellulose in the pulp to obtain phosphorylated pulp.

[Machine processing]
Ion-exchanged water was added to the phosphorylated pulp to prepare a 1.0% by mass pulp dispersion. This pulp dispersion was passed 5 times at a pressure of 245 MPa with a wet atomizer (Ultimizer manufactured by Sugino Machine Limited) to obtain a fine fibrous cellulose dispersion.

[Sheet]
The concentration of the fine fibrous cellulose dispersion was adjusted so that the solid content concentration was 0.5% by mass. Then, 20 parts by mass of a 0.5% by mass aqueous solution of polyethylene oxide (PEO-18 manufactured by Sumitomo Seika Chemical Co., Ltd.) was added to 100 parts by mass of fine fibrous cellulose. Next, the dispersion was weighed so that the finished basis weight of the sheet was 37.5 g / m ² , developed on a commercially available acrylic plate, and dried in a constant temperature and humidity chamber at 35 ° C. and a relative humidity of 15%. A metal frame for damming (a gold frame having an inner dimension of 180 mm × 180 mm) was placed on the acrylic plate so as to have a predetermined basis weight. By the above procedure, a fine fibrous cellulose-containing sheet was obtained.

<Example 2>
In Example 1, a fine fibrous cellulose dispersion and a fine fibrous cellulose-containing sheet were obtained in the same manner as in Example 1 except that the pre-hydrolysis treatment time was set to 50 minutes.

<Example 3>
In Example 1, a fine fibrous cellulose dispersion and a fine fibrous cellulose-containing sheet were obtained in the same manner as in Example 1 except that the pre-hydrolysis treatment time was set to 100 minutes.

<Comparative example 1>
In Example 1, a fine fibrous cellulose dispersion and a fine fibrous cellulose-containing sheet were obtained in the same manner as in Example 1 except that prehydrolysis was not performed.

<Comparative example 2>
[Dephosphoric acid / dehemicellulose treatment of fine fibrous cellulose dispersion]
Ion-exchanged water was added to the fine fibrous cellulose dispersion obtained in Comparative Example 1 to adjust the solid content concentration of the fine fibrous cellulose to 0.215% by mass. 150 g of urea is dissolved in 1.5 L of this dispersion, and the entire amount is divided into a SUS container attached to a pulp air bath type research multi-digester (Matari Steel, FIN-01450), and the temperature is 100 ° C. for 1 hour. Hydrolysis treatment was performed. A certain amount of the dispersed liquid after heating was taken and centrifuged at a condition of 15000 G × 10 minutes using a cooling high-speed centrifuge (Kokusan Co., Ltd., H-2000B). Then, the supernatant was removed, and ion-exchanged water was added to the obtained precipitate so as to have the same volume as the original volume, and the mixture was dispersed. The operation of centrifugation and dispersion of the precipitate in ion-exchanged water was repeated once more to remove the residual urea.

Next, an ion exchange resin having a volume ratio of 1/10 was added to the fine fibrous cellulose dispersion, and the mixture was shaken for 1 hour. Then, the fine fibrous cellulose dispersion was desalted by pouring it onto a mesh having a mesh size of 90 μm and separating the resin and the dispersion three times in total. The first time using a strong acid ion exchange resin (manufactured by Organo Corporation, Amber Jet 1024; conditioned), and the second time using a strong basic ion exchange resin (manufactured by Organo Corporation, Amber Jet 4400; conditioned). went. The third treatment was performed in the same manner as the first treatment. By the above procedure, a fine fibrous cellulose dispersion having desorbed phosphate groups and hemicellulose was obtained.

[Sheet]
The concentration of the fine fibrous cellulose dispersion was adjusted so that the solid content concentration was 0.2% by mass. Then, 20 parts by mass of a 0.2% by mass aqueous solution of polyethylene oxide (“PEO-18” manufactured by Sumitomo Seika Chemical Co., Ltd.) was added to 100 parts by mass of the fine fibrous cellulose. Next, the dispersion was weighed so that the finished basis weight of the sheet was 37.5 g / m ² , developed on a commercially available acrylic plate, and dried in a constant temperature and humidity chamber at 35 ° C. and a relative humidity of 15%. A metal frame for damming (a gold frame having an inner dimension of 180 mm × 180 mm) was placed on the acrylic plate so as to have a predetermined basis weight. By the above procedure, a fine fibrous cellulose-containing sheet was obtained.

<Comparative example 3>
In Comparative Example 2, a fine fibrous cellulose dispersion and a fine fibrous cellulose-containing sheet were obtained in the same manner as in Comparative Example 2 except that the hydrolysis treatment time was set to 4 hours.

<Comparative example 4>
In Example 1, a fine fibrous cellulose dispersion and a fine fibrous cellulose-containing sheet were obtained in the same manner as in Example 1 except that TEMPO oxidized pulp was used instead of phosphorylated pulp. The TEMPO oxide pulp used was produced according to the following procedure.

[Production of TEMPO Oxidized Pulp (TEMPO Oxidation Reaction)]
The bleached pulp obtained in Example 1 was collected by 100 parts by mass by dry mass, and 1.25 parts by mass of TEMPO and 12.5 parts by mass of sodium bromide were dispersed in 10000 parts by mass of water. Then, a 13 mass% sodium hypochlorite aqueous solution was added to 1.0 g of pulp so that the amount of sodium hypochlorite was 8.0 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 to 11, and when no change was observed in the pH, the reaction was considered to be completed.

[Washing of TEMPO oxidized pulp]
Then, this pulp slurry is dehydrated to obtain a dehydrated sheet, and then 5000 parts by mass of ion-exchanged water is poured, stirred and uniformly dispersed, and then filtered and dehydrated to obtain a dehydrated sheet. The process is repeated twice. rice field. The amount of substituent (carboxy group) introduced as measured by the titration method was 1.5 mmol / g.

[evaluation]
[Hemicellulose content]
200 mg of the bleached pulp obtained by the bleaching steps of Examples and Comparative Examples was collected in absolute dry mass, and 7.5 ml of 72% sulfuric acid was added thereto. Then, it was placed in a shaking constant temperature bath and stirred at 30 ° C. and 160 rpm for 60 minutes to hydrolyze the previous stage. Next, 30 μl of the hydrolyzed bleached pulp dispersion in the previous step was placed in a 1.5 ml tube containing 840 μl of ultrapure water, and stirred to dilute to a sulfuric acid concentration of 4% by mass. Then, it was treated in an autoclave at 121 ° C. for 1 hour, and the subsequent hydrolysis treatment was performed. The polysaccharide contained in the bleached pulp was hydrolyzed to a monosaccharide by the two hydrolysis treatments of the first stage and the second stage.

Then, using ion chromatography (Dionex, ICS-5000) equipped with a column (Dionex, CarboPac PA1), the glucose unit content C _gl , and the xylose unit, mannose unit, galactose unit, and arabinose unit. the content (respectively _{C xyl, C man, C gal} , and _{C ara)} was quantified. The content rate (mass%) of each unit was calculated with the total of glucose unit, xylose unit, mannose unit, galactose unit and arabinose unit as 100% by mass.
In the analysis by ion chromatography, the flow rate was set to 1 ml / min and the column temperature was set to room temperature. Water was used as the mobile phase, and a 0.3 N aqueous sodium hydroxide solution, a 0.1 N aqueous potassium hydroxide solution, and a 0.25 N aqueous sodium carbonate solution were used as the washing liquid. In the analysis, arabinose, galactose, glucose, xylose, and mannose are separated and eluted in this order. The detected peak was analyzed using analysis software (PeekNet) manufactured by Dionex.
From the quantified content, the ratio of the hemicellulose-derived monosaccharide content to the glucose content was taken according to the following formula, and used as an index of the hemicellulose content of the fine fibrous cellulose dispersion and the fine fibrous cellulose-containing sheet.
(C _xyl + C _man + C _gal + C _ara ) / C _glu

[Phosphate group amount]
The fine fibrous cellulose dispersions obtained in Examples and Comparative Examples were diluted with ion-exchanged water so that the solid content concentration was 0.2% by mass, treated with an ion-exchange resin, and titrated with an alkali. The amount of phosphate group was measured by. In the treatment with an ion exchange resin, a strongly acidic ion exchange resin (manufactured by Organo Corporation, Amber Jet 1024; conditioned) having a volume ratio of 1/10 is added to 0.2% by mass of a fine fibrous cellulose dispersion, and 1 The time was shaken. Then, the resin and the slurry were separated by pouring on a mesh having a mesh size of 90 μm. In the titration using alkali, the change in the value of electrical conductivity shown by the slurry was measured while adding a 0.1 N sodium hydroxide aqueous solution to the fine fibrous cellulose dispersion after ion exchange. The amount of alkali (mmol) required in the first region of the curve shown in FIG. 1 is divided by the solid content (g) in the fine fibrous cellulose dispersion to be titrated, and the amount of phosphate groups (mmol). / G).

[Total light transmittance of fine fibrous cellulose dispersion]
The fine fibrous cellulose dispersions obtained in Examples and Comparative Examples are diluted with ion-exchanged water so that the solid content concentration is 0.2% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). did. Then, in accordance with JIS K 7361, the total light transmittance (%) was measured using a haze meter (HM-150 manufactured by Murakami Color Technology Research Institute). In the measurement, calibration was performed using a glass cell filled with ion-exchanged water.

[Haze of fine fibrous cellulose dispersion]
The fine fibrous cellulose dispersions obtained in Examples and Comparative Examples are diluted with ion-exchanged water so that the solid content concentration is 0.2% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). did. Then, according to JIS K7163, the haze (%) was measured using a haze meter (HM-150 manufactured by Murakami Color Technology Research Institute). In the measurement, calibration was performed using a glass cell filled with ion-exchanged water.

[Yellowness of fine fibrous cellulose dispersion]
The fine fibrous cellulose dispersions obtained in Examples and Comparative Examples are diluted with ion-exchanged water so that the solid content concentration is 1.0% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). did. Then, the glass cell was covered with a lid, and the glass cell was allowed to stand in a constant temperature and humidity chamber at 40 ° C. and a relative humidity of 90% for 240 hours. Next, the yellowness of the fine fibrous cellulose dispersion was evaluated according to the following criteria by visually observing from the front with a printer paper (manufactured by Fuji Xerox Co., Ltd., C2r) as a background.
◎: No yellowness ○: Slightly yellowish △: Clearly yellowish

[Total light transmittance of fine fibrous cellulose-containing sheet]
In accordance with JIS K 7361, the total light transmittance of the fine fibrous cellulose-containing sheets obtained in Examples and Comparative Examples was measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute).

[Haze of fine fibrous cellulose-containing sheet]
According to JIS K 7163, the haze of the fine fibrous cellulose-containing sheet obtained in Examples and Comparative Examples was measured using a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute).

[Yellowness (YI) of fine fibrous cellulose-containing sheet before and after heating]
In accordance with JIS K 7373, the yellowness (YI) of the fine fibrous cellulose-containing sheets obtained in Examples and Comparative Examples before and after heating was measured using a colorimeter (Color Cutei manufactured by Suga Test Instruments Co., Ltd.). .. Moreover, the absolute value of the difference of YI before and after heating was evaluated as ΔYI. The heating conditions were vacuum drying at 200 ° C. for 4 hours.

[result]
The evaluation results are shown in Table 1.

As it is evident from Table _1, maintaining the _{(C xyl + C man + C} gal + C ara) / C glu value is less Examples 1-3 (high total light transmittance, low haze) high transparency At the same time, a fine fibrous cellulose dispersion with suppressed yellowness and a fine fibrous cellulose-containing sheet were obtained. By reducing the value of _{(C xyl + C man + C} gal + C ara) / C glu, YI and ΔYI after heating was also suppressed.
On the other hand, in Comparative Examples 1 and 4 having a large hemicellulose content, although the fine fibrous cellulose dispersion and the fine fibrous cellulose-containing sheet were highly transparent, the yellowness was higher than that of the examples. ..
Further, in Comparative Examples 2 and 3 in which the dephosphoric acid and the dehemicellulose of the fine fibrous cellulose dispersion were performed, the yellowness of the fine fibrous cellulose dispersion and the fine fibrous cellulose-containing sheet was slightly suppressed by the effect of the dehemicellulose. Although it was possible, the dephosphoric acid aggregated the fine fibrous cellulose, resulting in a decrease in transparency.

In equation (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (an integer of n = 1 or more and n or less) and α'are independent of each other. Represents O ⁻ , R or OR. R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched chain hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched chain hydrocarbon group. , Aromatic groups, or inducing groups thereof; β ^{b +} is a monovalent or higher cation consisting of an organic or inorganic substance.

The haze of the fine fibrous cellulose-containing slurry having a solid content concentration of fine fibrous cellulose of 0.2% by mass is preferably 25% or less, more preferably 20% or less, and 10% or less. Is more preferable, and 5% or less is particularly preferable. The lower limit of the haze of the fine fibrous cellulose-containing slurry is not particularly limited, but may be, for example, 0% or 0.5%.
The haze of the fine fibrous cellulose-containing sheet is diluted with ion-exchanged water so that the solid content concentration in the slurry is 0.2% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). conforms to JIS K 71 36, measured using a haze meter (Murakami color Research Laboratory Co., HM-150). In the measurement, calibration is performed with a glass cell filled with ion-exchanged water.

The haze of the fine fibrous cellulose-containing sheet is preferably 25% or less, more preferably 20% or less, further preferably 10% or less, and particularly preferably 5% or less.
Incidentally, the haze of the microfibrous cellulose-containing sheet conforms to JIS K 71 36, measured using a haze meter (Murakami Color Research Laboratory Co., HM-150).

[Haze of fine fibrous cellulose dispersion]
The fine fibrous cellulose dispersions obtained in Examples and Comparative Examples are diluted with ion-exchanged water so that the solid content concentration is 0.2% by mass, and then injected into a glass cell (dimensions: 45 mm × 42 mm × 12 mm). did. Then, conforms to the JIS K71 36, haze meter (Murakami Color Research Laboratory Co., Ltd., HM-150) was measured haze (%) using the. In the measurement, calibration was performed using a glass cell filled with ion-exchanged water.

[Haze of fine fibrous cellulose-containing sheet]
Conforming to JIS K 71 36, haze meter (Murakami Color Research Laboratory Co., HM-150) was measured haze of the obtained fine fibrous cellulose-containing sheet in the examples and comparative examples with.

As it is evident from Table _1, maintaining the _{(C xyl + C man + C} gal + C ara) / C glu value is less Examples 1-3 (high total light transmittance, low haze) high transparency At the same time, a fine fibrous cellulose dispersion with suppressed yellowness and a fine fibrous cellulose-containing sheet were obtained. By reducing the value of _{(C xyl + C man + C} gal + C ara) / C glu, YI and ΔYI after heating was also suppressed.
On the other hand, in Comparative Examples 1 and 4, although the fine fibrous cellulose dispersion and the fine fibrous cellulose-containing sheet were highly transparent, the yellowness was higher than that of Examples.
Further, in Comparative Examples 2 and 3 in which the dephosphoric acid and the dehemicellulose of the fine fibrous cellulose dispersion were performed, the yellowness of the fine fibrous cellulose dispersion and the fine fibrous cellulose-containing sheet was slightly suppressed by the effect of the dehemicellulose. Although it was possible, the dephosphoric acid aggregated the fine fibrous cellulose, resulting in a decrease in transparency.

Claims (8)

A fine fibrous cellulose-containing product containing fine fibrous cellulose having a substituent derived from a phosphoric acid group or a phosphoric acid group.
The fine fibrous cellulose-containing material contains glucose units and contains
The glucose unit content is C _gl (mass%), the xylose unit content is C _xyl (mass%), the mannose unit content is C _man (mass%), and the galactose unit content is C _gal (mass). %), when the content of arabinose units and _{C ara (wt%),} is 0.1 or less the value of _{(C xyl + C man + C} gal + C ara) / C glu,
A fine fibrous cellulose-containing substance having a phosphoric acid group or a substituent derived from the phosphoric acid group of the fine fibrous cellulose having a content of 0.5 mmol / g or more. The fine fibrous cellulose-containing product according to claim 1, wherein the haze is 25% or less. The fine fibrous cellulose-containing product according to claim 1 or 2, wherein the total light transmittance is 87% or more. A fine fibrous cellulose-containing sheet formed from the fine fibrous cellulose-containing material according to any one of claims 1 to 3. The fine fibrous cellulose-containing sheet according to claim 4, which has a YI value of 1.4 or less. The fine fibrous form according to claim 4 or 5, wherein the absolute value (ΔYI value) of the amount of change in the YI value before and after the fine fibrous cellulose-containing sheet is allowed to stand under a vacuum condition of 200 ° C. for 4 hours is 30 or less. Cellulose-containing sheet. The fine fibrous cellulose-containing sheet according to any one of claims 4 to 6, wherein the haze is 25% or less. The fine fibrous cellulose-containing sheet according to any one of claims 4 to 7, wherein the total light transmittance is 87% or more.

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