JP6680382B1 - Composition - Google Patents

Abstract

An object of the present invention is to provide a sheet having high transparency and being suppressed from being colored. The present invention is a composition comprising a fibrous cellulose having a fiber width of 1000 nm or less and a basic component, wherein the fibrous cellulose has a phosphite group or a substituent derived from a phosphite group. And the base component is at least one selected from monovalent organic bases and monovalent inorganic bases, and the solid content of the composition is 85 mass% or more. [Selection diagram] None

Description

  The present invention relates to compositions. Specifically, the present invention relates to a composition containing fibrous cellulose, preferably a sheet containing fibrous cellulose.

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

  As the fibrous cellulose, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Further, a sheet composed of such fine fibrous cellulose and a composite containing fine fibrous cellulose and a resin have been developed. It is known that, in a sheet or composite containing fine fibrous cellulose, the number of contact points between fibers remarkably increases, so that the tensile strength and the like are greatly improved.

  For example, Patent Documents 1 to 3 disclose sheets containing fine fibrous cellulose and a resin. Patent Document 1 discloses a cellulose fiber composite containing fine fibrous cellulose and a matrix, and Patent Document 2 discloses a polyvinyl alcohol film containing fine fibrous cellulose and a polyvinyl alcohol-based resin. In addition, in Patent Document 3, 1 selected from the group consisting of a thermoplastic resin and a curable resin selected from an epoxy resin, a (meth) acrylic resin, a phenol resin, an unsaturated polyester resin, a polyurethane resin, or a polyimide resin. A resin composition containing one or more resins and a modified cellulose fiber is disclosed.

  Further, in Patent Documents 4 to 6, it is considered to make the fine fibrous cellulose obtained by a predetermined manufacturing method into a sheet. For example, Patent Document 4 discloses a defibrating step of defibrating a cellulose fiber raw material to obtain defibrated cellulose fibers, and a method for producing a cellulose fiber polymer using the defibrated cellulose fibers to obtain a cellulose fiber polymer. ing. In Patent Document 5, an oil component is added to cellulose nanofibers to which carboxymethylcellulose or carboxymethylcellulose nanofibers are added, and the mixture is stirred with a mixer and / or a stirring and defoaming device and then dried to form a cellulose nanofiber film. A method of doing so is disclosed. Patent Document 6 discloses a method for producing cellulose, which comprises a step of contacting raw material cellulose with an organic acid in water and a step of defibrating the cellulose.

JP, 2011-144363, A JP, 2017-052840, A JP, 2017-052940, A International Publication No. 2012/067113 JP, 2017-048293, A JP, 2010-222536, A

The present inventors, while conducting research on a sheet containing fine fibrous cellulose, found that the fine fibrous cellulose-containing sheet may have reduced transparency or coloration.
Therefore, an object of the present invention is to enhance transparency and suppress coloring in a sheet containing fine fibrous cellulose.

As a result of intensive studies to solve the above problems, the present inventors have determined that a composition containing fine fibrous cellulose having a substituent derived from a phosphite group or a phosphite group has a predetermined content. It has been found that a sheet having high transparency and suppressed coloration can be obtained by containing a basic component.
Specifically, the present invention has the following configurations.

[1] A composition containing a fibrous cellulose having a fiber width of 1000 nm or less and a base component,
Fibrous cellulose has a substituent derived from a phosphite group or a phosphite group,
The base component is at least one selected from monovalent organic bases and monovalent inorganic bases,
A composition having a solid content of 85% by mass or more.
[2] The composition according to [1], which is a sheet.
[3] The composition according to [1] or [2], wherein the base component is a monovalent organic base.
[4] The composition according to [1] or [2], wherein the base component is a monovalent inorganic base.
[5] The composition according to [4], wherein the monovalent inorganic base is sodium hydroxide or potassium hydroxide.
[6] The composition according to any one of [1] to [5], which further contains a resin.
[7] The composition according to any one of [1] to [6], wherein the content of the base component is 0.05% by mass or more and 8.0% by mass or less based on the total mass of the composition.
[8] The composition according to any one of [1] to [7], wherein the composition is a sheet, and the surface pH of the sheet is 5.00 or more and 8.00 or less.
[9] The composition according to any one of [1] to [8], wherein the composition is a sheet and the haze of the sheet is 4.0% or less.
[10] The composition is a sheet,
The composition according to any one of [1] to [9], wherein the YI increase rate calculated by the following formula is 950% or less;
YI increase rate (%) = (yellowness of sheet after heating−yellowness of sheet before heating) / yellowness of sheet before heating × 100
In the above formula, the yellowness of the sheet after heating is the yellowness measured according to JIS K 7373 after hot pressing the sheet at 180 ° C. and 0.5 MPa for 1 minute, and the yellowness of the sheet before heating is It is the yellowness degree measured according to JIS K 7373 before hot pressing.

  According to the present invention, a fine fibrous cellulose-containing sheet having high transparency and being suppressed from being colored can be obtained.

FIG. 1 is a graph showing the relationship between the dropping amount of NaOH and the pH of a slurry containing fibrous cellulose having a phosphorus oxo acid group.

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

(Composition containing fine fibrous cellulose)
The present invention relates to a composition containing fibrous cellulose having a fiber width of 1000 nm or less and a base component. Here, the fibrous cellulose has a phosphite group or a substituent derived from a phosphite group, and the base component is at least one selected from a monovalent organic base and a monovalent inorganic base. . The solid content of the composition is 85% by mass or more. In the present specification, fibrous cellulose having a fiber width of 1000 nm or less may be referred to as fine fibrous cellulose.

  Since the composition of the present invention has the above constitution, it is possible to form a sheet having excellent transparency. Further, the sheet formed from the composition of the present invention is suppressed from being colored, and particularly, yellow is suppressed. The composition of the present invention is preferably in sheet form, and the present invention also relates to a fine fibrous cellulose-containing sheet. Below, the sheet | seat which is a preferable embodiment of this invention is demonstrated.

(Fine fibrous cellulose-containing sheet)
The haze of the sheet is preferably 4.0% or less, more preferably 3.0% or less, further preferably 2.0% or less, and particularly preferably 1.4% or less. preferable. The lower limit of the haze of the sheet is not particularly limited and may be 0.0%. By setting the haze of the sheet within the above range, a sheet having more excellent transparency can be obtained. The haze of the sheet is a value measured according to JIS K 7136 using, for example, a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.).

The YI increase rate calculated by the following formula of the sheet is preferably 950% or less, more preferably 900% or less, further preferably 800% or less, and further preferably 700% or less, It is particularly preferably at most 600%. The YI increase rate may be 0%.
YI increase rate (%) = (yellowness of sheet after heating−yellowness of sheet before heating) / yellowness of sheet before heating × 100
In the above formula, the yellowness of the sheet after heating is the yellowness measured according to JIS K 7373 after hot pressing the sheet at 180 ° C. and 0.5 MPa for 1 minute, and the yellowness of the sheet before heating is It is the yellowness degree measured according to JIS K 7373 before hot pressing. For measuring the yellowness, for example, Color Cute i (manufactured by Suga Test Instruments Co., Ltd.) can be used.
By setting the YI increase rate within the above range, a sheet in which yellow coloring is further suppressed can be obtained.

  The yellowness (YI) of the sheet (sheet before heating) measured according to JIS K 7373 is preferably 1.0 or less, and more preferably less than 0.7. The yellowness (YI) measured according to JIS K 7373 after hot pressing the sheet at 180 ° C. and 0.5 MPa for 1 minute is preferably 6.0 or less, and 5.0 or less. Is more preferable, 4.5 or less is more preferable, 4.0 or less is still more preferable, and 3.9 or less is particularly preferable. The lower limit of the yellowness index (YI) is not particularly limited and may be 0.0.

ΔYI calculated by the following formula of the present invention is preferably 5.5 or less, more preferably 5.0 or less, further preferably 4.5 or less, and 4.0 or less. Is particularly preferred.
ΔYI = (yellowness of sheet after heating) − (yellowness of sheet before heating)
In the above formula, the yellowness of the sheet after heating is the yellowness measured according to JIS K 7373 after hot pressing the sheet at 180 ° C. and 0.5 MPa for 1 minute, and the yellowness of the sheet before heating is It is the yellowness degree measured according to JIS K 7373 before hot pressing.
In the sheet formed from the composition of the present invention, the increase in yellowness of the sheet is suppressed even after heating at a high temperature of 180 ° C.

  The total light transmittance of the sheet is preferably 70% or more, more preferably 80% or more, and further preferably 85% or more. The total light transmittance of the sheet is a value measured according to JIS K 7361, for example, using a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.).

  The solid content of the sheet may be 85% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 99% by mass or more. The solid content of the sheet may be 100% by mass. That is, most of the sheet is solid, and the content of the solvent is small.

  The content of the fine fibrous cellulose in the sheet is preferably 1% by mass or more, more preferably 10% by mass or more, and more preferably 20% by mass or more with respect to the total mass of the solid content in the sheet. More preferably, it is more preferably 30% by mass or more, and particularly preferably 50% by mass or more. On the other hand, the content of the fine fibrous cellulose in the sheet is preferably 99% by mass or less based on the total mass of solids in the sheet.

  The sheet may include a solvent. Examples of the solvent include water and organic solvents. Examples of the organic solvent include methanol, ethanol, n-propyl alcohol, isopropyl alcohol (IPA), 1-butanol, m-cresol, glycerin, acetic acid, pyridine, tetrahydrofuran (THF), acetone, methyl ethyl ketone (MEK), ethyl acetate. , Aniline, N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF), hexane, cyclohexane, benzene, toluene, p-xylene, diethyl ether chloroform and the like. it can. The content of the solvent in the sheet may be 10% by mass or less based on the total mass of the sheet, preferably 5% by mass or less, and more preferably 1% by mass or less.

  The pH of the surface of the sheet is preferably 5.00 or higher. Further, the pH of the surface of the sheet is preferably 8.00 or less, more preferably 7.50 or less, further preferably 7.00 or less, and particularly preferably 6.50 or less. preferable. The surface pH of the sheet is, for example, a value measured by a calibrated pH meter (F-53 manufactured by Horiba, Ltd.).

  The pH of the surface of the sheet is preferably within the above range, which means that the sheet contains a basic component. Here, the base component contained in the sheet is at least one selected from a monovalent organic base and a monovalent inorganic base. Such a base component is preferably added so that the pH of the surface of the sheet is within the above range. For example, the content of the base component in the sheet is preferably 0.05 mass% or more, more preferably 0.07 mass% or more, and 0.085 mass% with respect to the total mass of the sheet. It is more preferable that the above is satisfied. The content of the base component in the sheet is preferably 8.0% by mass or less, more preferably 7.0% by mass or less, and further preferably 6.0% by mass or less, The content is more preferably 5.0% by mass or less, still more preferably 3.0% by mass or less, and particularly preferably 2.0% by mass or less. The pH of the surface of the sheet is also adjusted by appropriately selecting the manufacturing conditions. For example, it is preferable to adopt a condition in which the base component is added to the slurry before being formed into a sheet, and then the sheet is formed so that the base component remains in the sheet. The content of the basic component is the content of the basic component remaining in the sheet obtained through the sheet forming process. The content of the base component can be quantified by, for example, an ion chromatography method.

  The thickness of the sheet is not particularly limited, but is preferably 5 μm or more, more preferably 10 μm or more, and further preferably 20 μm or more. The upper limit of the thickness of the sheet is not particularly limited, but it is preferably 1000 μm or less. The thickness of the sheet can be measured by, for example, a stylus thickness meter (Millitron 1202D, manufactured by Marl).

The basis weight of the sheet is not particularly limited, but is preferably 10 g / m ² or more, more preferably 20 g / m ² or more, and further preferably 30 g / m ² or more. The basis weight of the sheet is not particularly limited, but is preferably 200 g / m ² or less, more preferably 150 g / m ² or less. Here, the basis weight of the sheet can be calculated based on JIS P 8124, for example.

The density of the sheet is not particularly limited, but is preferably 0.1 g / cm ³ or more, more preferably 0.5 g / cm ³ or more, and further preferably 1.0 g / cm ³ or more. preferable. The density of the sheet is not particularly limited, but is preferably 5.0 g / cm ³ or less, and more preferably 3.0 g / cm ³ or less. Here, the density of the sheet can be calculated by measuring the thickness and mass of the sheet after conditioning the 50 mm square sheet at 23 ° C. and 50% relative humidity for 24 hours.

(Fine fibrous cellulose)
The composition (sheet) of the present invention has a fiber width of 1000 nm or less and contains fibrous cellulose (fine fibrous cellulose) having a phosphorous acid group or a substituent derived from a phosphorous acid group. The fiber width of the fibrous cellulose can be measured by, for example, observing with an electron microscope.

  The average fiber width of the fibrous cellulose is, for example, 1000 nm or less. The average fiber width of the fibrous cellulose is, for example, preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, further preferably 2 nm or more and 50 nm or less, and 2 nm or more and 10 nm or less. Especially preferred. By setting the average fiber width of the fibrous cellulose to 2 nm or more, it is possible to prevent the fibrous cellulose from being dissolved in water and more easily exhibit the effect of improving the strength, rigidity, and dimensional stability of the fibrous cellulose. it can. The fibrous cellulose is, for example, monofilament cellulose.

The average fiber width of the fibrous cellulose is measured, for example, using an electron microscope as follows. First, an aqueous suspension of fibrous cellulose having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and this suspension is cast on a hydrophilized carbon film-covered grid to obtain a TEM observation sample. And When a wide fiber is included, an SEM image of the surface cast on glass may be observed. Then, observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times or 50000 times depending on the width of the fiber to be observed. However, the sample, observation conditions and magnification are adjusted so as to satisfy the following conditions.
(1) One straight line X is drawn at an arbitrary position in the observed image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicular to the straight line 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 from the observed image satisfying the above conditions. In this way, at least three sets of observation images of the surface portions that do not overlap each other are obtained. Then, for each image, the width of the fiber intersecting the straight line X and the straight line Y is read. Thereby, the fiber width of at least 20 fibers × 2 × 3 = 120 fibers is read. Then, the average value of the read fiber widths is set as the average fiber width of the fibrous cellulose.

  The fiber length of the fibrous cellulose is not particularly limited, but is preferably 0.1 μm or more and 1000 μm or less, more preferably 0.1 μm or more and 800 μm or less, and further preferably 0.1 μm or more and 600 μm or less. preferable. By setting the fiber length within the above range, breakage of the crystalline region of the fibrous cellulose can be suppressed. It is also possible to set the slurry viscosity of the fibrous cellulose within an appropriate range. The fiber length of the fibrous cellulose can be determined by image analysis using TEM, SEM, or AFM, for example.

  The fibrous cellulose preferably has a type I crystal structure. Here, the fact that the fibrous cellulose has an I-type crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418Å) monochromated with graphite. Specifically, it can be identified by having typical peaks at two positions near 2θ = 14 ° or more and 17 ° or less and around 2θ = 22 ° or more and 23 ° or less.

  The proportion of the I-type crystal structure in the fine fibrous cellulose is, for example, preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. Thereby, further excellent performance can be expected in terms of heat resistance and low linear thermal expansion coefficient. The crystallinity is determined by measuring the X-ray diffraction profile and using the pattern in a conventional manner (Seagal et al., Textile Research Journal, Vol. 29, page 786, 1959).

  The axial ratio (fiber length / fiber width) of the fibrous cellulose is not particularly limited, but is preferably 20 or more and 10000 or less, and more preferably 50 or more and 1000 or less. By setting the axial ratio to the above lower limit or more, it is easy to form a sheet containing fine fibrous cellulose. Further, it is easy to obtain sufficient thickening when the solvent dispersion is prepared. It is preferable that the axial ratio is not more than the above upper limit because handling such as dilution becomes easy when handling fibrous cellulose as an aqueous dispersion.

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

  Fibrous cellulose has a phosphite group or a substituent derived from a phosphite group. In the present specification, the phosphite group or the substituent derived from the phosphite group is also simply referred to as a phosphite group.

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

  In the formula (2), b is a natural number, m is an arbitrary number, and b × m = 1. α is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group , Unsaturated-cyclic hydrocarbon groups, aromatic groups, or derivatives thereof. Of these, α is particularly preferably a hydrogen atom. It should be noted that α in formula (2) does not include a group derived from a cellulose molecular chain.

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

  In addition, the derivative group in α is a functional group in which at least one of functional groups such as a carboxy group, a hydroxy group, or an amino group is added or substituted to the main chain or side chain of each of the above hydrocarbon groups. Examples thereof include groups, but are not particularly limited. The number of carbon atoms constituting the main chain of R is not particularly limited, but is preferably 20 or less, more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R in the above range, the molecular weight of the phosphite group can be set in an appropriate range, the permeation into the fiber raw material is facilitated, and the yield of fine cellulose fibers is increased. It can also be increased.

Β ^{b +} in the formula (2) is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or more cations composed of an organic substance include aliphatic ammonium and aromatic ammonium, and examples of monovalent or more cations composed of an inorganic substance include an alkali metal ion such as sodium, potassium or lithium, Examples thereof include cations of divalent metals such as calcium and magnesium, and hydrogen ions, but are not particularly limited. These may be applied alone or in combination of two or more. As the cation having a valence of 1 or more consisting of an organic substance or an inorganic substance, sodium or potassium ions which are less likely to yellow when the β-containing fiber raw material is heated and which are industrially applicable are preferable, but not particularly limited.

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

In the formula (1), a and b are natural numbers and m is an arbitrary number (however, a = b × m). a of α and α ′ are O ⁻ , and the rest are OR. Here, R is a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. It is a hydrocarbon group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or a derivative group thereof. Note that α in the formula (1) may be a group derived from a cellulose molecular chain.

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

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

The fact that the fibrous cellulose has a phosphite group as a substituent means that it is a tautomer of the phosphite group at around 1210 cm ^{-1 by} measuring the infrared absorption spectrum of a dispersion liquid containing fine fibrous cellulose. This can be confirmed by observing the absorption based on P = O of the phosphonic acid group. In addition, the fact that the fibrous cellulose has a phosphate group as a substituent means that the dispersion liquid containing the fibrous cellulose is subjected to infrared absorption spectrum measurement, and the absorption based on P = O of the phosphate group at about 1230 cm ^-1. It can be confirmed by observing. The fact that the fibrous cellulose has a phosphite group or a phosphate group as a substituent can also be confirmed by a method of confirming a chemical shift using NMR, a method of combining titration with elemental analysis, or the like.

The introduction amount of the phosphite group to the fibrous cellulose is, for example, preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol per 1 g (mass) of the fibrous cellulose. / G or more is more preferable, and 1.00 mmol / g or more is particularly preferable. Further, the introduction amount of the phosphite group to the fibrous cellulose is, for example, preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less per 1 g (mass) of the fibrous cellulose. It is more preferably 0.50 mmol / g or less, and particularly preferably 3.00 mmol / g or less. By setting the introduction amount of the phosphite group within the above range, it is possible to facilitate the miniaturization of the fiber raw material and increase the stability of the fibrous cellulose. Further, by setting the introduction amount of the phosphite group within the above range, good properties can be exhibited in a sheet or the like containing fibrous cellulose.
Here, the denominator in the unit mmol / g represents the mass of the fibrous cellulose when the counter ion of the phosphite group is a hydrogen ion (H ⁺ ).

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

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

In addition, since the denominator indicates the mass of the acid-type fibrous cellulose, the above-mentioned phosphorus-oxo acid group introduction amount (mmol / g) is the amount of the phosphorus-oxo acid group contained in the acid-type fibrous cellulose (hereinafter, the phosphorus-oxo acid group amount (Called acid type)). On the other hand, when the counter ion of the phosphorus oxo acid group is substituted with an arbitrary cation C so as to have a charge equivalent, the denominator is converted into the mass of the fibrous cellulose when the cation C is the counter ion. Thus, the amount of phosphorus oxo acid group (hereinafter, amount of phosphorus oxo acid group (C type)) that the fibrous cellulose having the cation C as a counter ion has can be obtained.
That is, it is calculated by the following calculation formula.
Phosphorous oxo acid group amount (C type) = phosphorus oxo acid group amount (acid type) / {1+ (W-1) × A / 1000}
A [mmol / g]: Total anion amount derived from phosphorus oxo acid group in fibrous cellulose (total amount of dissociated acid of phosphorus oxo acid group)
W: Formula weight per valence of cation C (for example, 23 for Na and 9 for Al)

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

  In addition, in addition to the phosphite group, whether the phosphorous acid detected in the case of containing either or both of the phosphoric acid group and the condensed phosphoric acid group is derived from phosphorous acid, phosphoric acid, and condensed phosphoric acid As a method of distinguishing, for example, a method of performing the titration operation described above after performing a treatment of cleaving the condensed structure such as acid hydrolysis, or a treatment of converting a phosphite group into a phosphate group such as an oxidation treatment. Examples include a method of performing the above-mentioned titration operation after the operation.

<Production process of fine fibrous cellulose>
<Fiber raw material>
Fine fibrous cellulose is manufactured from a fiber raw material containing cellulose. The fiber raw material containing cellulose is not particularly limited, but pulp is preferably used because it is easily available and inexpensive. Pulps include, for example, wood pulp, non-wood pulp, and deinked pulp. The wood pulp is not particularly limited, and examples thereof include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP). ) And chemical pulp such as oxygen bleached kraft pulp (OKP), semi-chemical pulp such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP), etc. Examples include mechanical pulp. The non-wood pulp is not particularly limited, and examples thereof include cotton-based pulp such as cotton linter and cotton lint, and non-wood-based pulp such as hemp, straw and bagasse. The deinked pulp is not particularly limited, and examples thereof include deinked pulp made from waste paper. The pulp of this embodiment may be used alone or as a mixture of two or more kinds.
Among the above pulps, for example, wood pulp and deinked pulp are preferable from the viewpoint of easy availability. Further, among wood pulp, a viewpoint of a high yield of fine fibrous cellulose at the time of defibration treatment with a large cellulose ratio, and a long fiber fine fibrous cellulose with a small decomposition of cellulose in the pulp and a large axial ratio can be obtained. From the viewpoint, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are further preferable.

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

<Phosphite group introduction step>
In the phosphite group introducing step, at least one compound selected from compounds capable of introducing a phosphite group by reacting with a hydroxyl group contained in a fiber raw material containing cellulose (hereinafter, also referred to as “compound A”) , A step of acting on a fiber raw material containing cellulose. By this step, the phosphorous acid group-introduced fiber is obtained.

  In the phosphite group-introducing step according to the present embodiment, the reaction of the cellulose-containing fiber raw material with the compound A is carried out in the presence of at least one selected from urea and its derivatives (hereinafter, also referred to as “compound B”). You can go. On the other hand, the reaction of the fiber raw material containing cellulose and the compound A may be carried out in the state where the compound B does not exist.

  As an example of a method of allowing the compound A to act on the fiber raw material in the coexistence with the compound B, a method of mixing the compound A and the compound B with the fiber raw material in a dry state, a wet state or a slurry state can be mentioned. Of these, it is preferable to use a fiber raw material in a dry state or a wet state, and particularly preferable to use a fiber raw material in a dry state, since the reaction is highly uniform. The form of the fiber raw material is not particularly limited, but is preferably cotton-like or thin sheet-like, for example. The compound A and the compound B may be added to the fiber raw material in the form of powder or in the form of a solution dissolved in a solvent, or in the state of being heated to a melting point or higher and being melted. Of these, since the reaction is highly uniform, it is preferable to add them in the form of a solution dissolved in a solvent, particularly in the state of an aqueous solution. Further, the compound A and the compound B may be added to the fiber raw material at the same time, separately, or as a mixture. The method of adding the compound A and the compound B is not particularly limited, but when the compound A and the compound B are in the form of a solution, the fiber raw material may be immersed in the solution to absorb the liquid, and then taken out. The solution may be added dropwise. Also, the required amounts of compound A and compound B may be added to the fiber raw material, or excess amounts of compound A and compound B are respectively added to the fiber raw material, and then excess compound A and compound B are squeezed or filtered. May be removed.

  The compound A used in this embodiment is at least one compound selected from a compound having a phosphorous acid group and a salt thereof. Examples of the compound having a phosphorous acid group include phosphorous acid, and examples of the phosphorous acid include 99% phosphorous acid (phosphonic acid). Examples of the salt of the compound having a phosphite group include lithium salt, sodium salt, potassium salt and ammonium salt of phosphite, which can have various degrees of neutralization. Among these, from the viewpoint of high efficiency of introduction of phosphorus oxo acid group, easy improvement of defibration efficiency in the defibration step described later, low cost, and easy industrial application, phosphorous acid, phosphorus A sodium salt of an acid, a potassium salt of phosphorous acid, or an ammonium salt of phosphorous acid is preferably used.

  The addition amount of the compound A to the fiber raw material is not particularly limited, but when the addition amount of the compound A is converted into the phosphorus atomic weight, the addition amount of the phosphorus atom to the fiber raw material (absolute dry mass) is 0.5% by mass or more. It is preferably 100% by mass or less, more preferably 1% by mass or more and 50% by mass or less, and further preferably 2% by mass or more and 30% by mass or less. By setting the amount of phosphorus atoms added to the fiber raw material within the above range, the yield of fine fibrous cellulose can be further improved. On the other hand, by controlling the amount of phosphorus atoms added to the fiber raw material to be not more than the above upper limit, the effect of improving the yield and the cost can be balanced.

  The compound B used in this embodiment is at least one selected from urea and its derivatives as described above. Examples of the compound B include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like. From the viewpoint of improving the homogeneity of the reaction, the compound B is preferably used as an aqueous solution. From the viewpoint of further improving the homogeneity of the reaction, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved.

  The amount of the compound B added to the fiber raw material (absolute dry mass) is not particularly limited, but is preferably 1% by mass or more and 500% by mass or less, more preferably 10% by mass or more and 400% by mass or less, More preferably, it is 100% by mass or more and 350% by mass or less.

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

  In the phosphite group-introducing step, it is preferable to add or mix the compound A or the like to the fiber raw material and then subject the fiber raw material to heat treatment. As the heat treatment temperature, it is preferable to select a temperature at which the phosphorous acid group can be efficiently introduced while suppressing thermal decomposition or hydrolysis reaction of the fiber. The heat treatment temperature is, for example, preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower. Further, for the heat treatment, equipment having various heat mediums can be used, and for example, a stirring dryer, a rotary dryer, a disc dryer, a roll heater, a plate heater, a fluidized bed dryer, an air stream. A drying device, a reduced pressure drying device, an infrared heating device, a far infrared heating device, a microwave heating device, or a high frequency drying device may be used.

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

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

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

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

  The amount of the phosphite group introduced into the fiber raw material is, for example, preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol per 1 g (mass) of the fine fibrous cellulose. / G or more is more preferable, and 1.00 mmol / g or more is particularly preferable. The amount of the phosphite group introduced into the fiber raw material is, for example, preferably 5.20 mmol / g or less, more preferably 3.65 mmol / g or less, per 1 g (mass) of the fine fibrous cellulose. More preferably, it is 0.000 mmol / g or less. By controlling the amount of the phosphite group introduced to be 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.

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

<Alkali treatment process>
When producing fine fibrous cellulose, the fiber raw material may be subjected to an alkali treatment between the phosphite group introduction step and the defibration treatment step described later. The method of alkali treatment is not particularly limited, and examples thereof include a method of immersing the phosphite group-introduced fiber in an alkaline solution.

  The alkaline compound contained in the alkaline solution is not particularly limited, and may be an inorganic alkaline compound or an organic alkaline compound. In the present embodiment, it is preferable to use, for example, sodium hydroxide or potassium hydroxide as the alkali compound because of its high versatility. The solvent contained in the alkaline solution may be either water or an organic solvent. Among them, the solvent contained in the alkaline solution is preferably a polar solvent containing water or a polar organic solvent exemplified by alcohol, and more preferably an aqueous solvent containing at least water. As the alkaline solution, for example, an aqueous solution of sodium hydroxide or an aqueous solution of potassium hydroxide is preferable because of its high versatility.

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

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

<Acid treatment step>
When producing fine fibrous cellulose, the fiber raw material may be subjected to an acid treatment between the step of introducing a phosphite group and the defibration treatment step described below. For example, the phosphite group introduction step, the acid treatment, the alkali treatment and the defibration treatment may be performed in this order.

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

  The temperature of the acid solution in the acid treatment is not particularly limited, but is preferably 5 ° C. or higher and 100 ° C. or lower, and more preferably 20 ° C. or higher and 90 ° C. or lower. The immersion time in the acid solution in the acid treatment is not particularly limited, but is preferably 5 minutes or more and 120 minutes or less, more preferably 10 minutes or more and 60 minutes or less. The amount of the acid solution used in the acid treatment is not particularly limited, but for example, is preferably 100% by mass or more and 100000% by mass or less, and 1000% by mass or more and 10000% by mass or less based on the absolute dry mass of the fiber raw material. Is more preferable.

<Disentanglement treatment>
Fine fiber cellulose is obtained by defibrating the phosphite group-introduced fiber in the defibration process step. In the defibration processing step, for example, a defibration processing device can be used. The defibration processing device is not particularly limited, but includes, for example, a high-speed defibration machine, a grinder (stone mill type crusher), a high-pressure homogenizer or an ultra-high pressure homogenizer, a high-pressure collision crusher, a ball mill, a bead mill, a disc refiner, a conical refiner, a twin-screw machine. A kneader, a vibration mill, a homomixer under high speed rotation, an ultrasonic disperser, a beater, or the like can be used. Among the above-mentioned defibration treatment devices, it is more preferable to use a high-speed defibration machine, a high-pressure homogenizer, and an ultrahigh-pressure homogenizer, which are less affected by the grinding media and less likely to cause contamination.

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

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

  As described above, a slurry containing fine fibrous cellulose is obtained. The solid content concentration in the slurry can be appropriately adjusted. For example, the solid content concentration is preferably 0.1% by mass or more, and more preferably 0.5% by mass or more. The solid content concentration is preferably 50% by mass or less, more preferably 40% by mass or less.

(Base component)
The composition (sheet) of the present invention contains at least one base component selected from a monovalent organic base and a monovalent inorganic base. The base component may be one type or a combination of two or more types. By containing the above-mentioned base as the basic component, the haze of the sheet can be suppressed to a low level, and yellow coloring can be suppressed.

  The base component is preferably a monovalent organic base. The monovalent organic base is a monovalent organic basic compound, and examples of such an organic basic compound include an alkylamine having an alkyl group having 1 to 10 carbon atoms and an alkyl group having 1 to 10 carbon atoms. Examples thereof include an alkanoamine, a basic amino acid, an aromatic amine, and a heterocyclic amine. Of these, alkylamines are preferably used.

  The base component is preferably a monovalent inorganic base. The monovalent inorganic base is a monovalent inorganic basic compound, and examples of such an inorganic basic compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate, ammonia and carbonic acid. Examples thereof include ammonium hydrogen. Of these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are preferably used.

  The base component is preferably a strong base and preferably has a high solubility in water. The addition amount of the base component is preferably adjusted appropriately according to the pH and the solubility of the base component.

(Arbitrary component)
The composition (sheet) of the present invention preferably further contains a resin in addition to the fine fibrous cellulose and the basic component described above. Examples of the resin include acrylic resin, polycarbonate resin, polyester resin, polyamide resin, silicone resin, fluorine resin, chlorine resin, epoxy resin, melamine resin, phenol resin, polyurethane resin, Examples thereof include diallyl phthalate resin, polyol resin, polyether resin, cellulose derivative, polyethylene resin and the like. Among them, the composition (sheet) of the present invention preferably contains at least one selected from a polyol resin, a polyether resin and a cellulose derivative.

  The composition (sheet) of the present invention may further contain a water-soluble polymer as a resin, in addition to the resin species described above. The water-soluble polymer, for example, xanthan gum, guar gum, tamarind gum, carrageenan, locust bean gum, quince seed, alginic acid, pullulan, carrageenan, pectin and the like thickening polysaccharides, cationized starch, raw starch, oxidized Examples thereof include starches such as starch, etherified starch, esterified starch and amylose, glycerins such as glycerin, diglycerin and polyglycerin, hyaluronic acid and metal salts of hyaluronic acid.

  The content of the resin contained in the sheet is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more based on the total mass of the solid content in the sheet. More preferable. Further, the content of the resin contained in the sheet is preferably 99% by mass or less, more preferably 95% by mass or less, and 90% by mass or less with respect to the total solid mass of the sheet. Is more preferable.

  Other optional components include, for example, surfactants, organic ions, coupling agents, inorganic layered compounds, inorganic compounds, leveling agents, preservatives, defoamers, organic particles, lubricants, antistatic agents, and UV protection. Agents, dyes, pigments, stabilizers, magnetic powders, orientation promoters, plasticizers, dispersants, cross-linking agents, antioxidants, etc., and the composition (sheet) of the present invention includes one or two of the above components. It may contain more than one species.

  The content of the above-described components contained in the sheet is preferably 40% by mass or less, more preferably 30% by mass or less, and 20% by mass or less, with respect to the total mass of the solid content in the sheet. Is more preferable.

(Sheet manufacturing process)
The manufacturing process of the sheet, the fine fibrous cellulose having a phosphite group or a substituent derived from a phosphite group, a step of obtaining a slurry containing a basic component, and coating the slurry on a substrate Or a paper making step of making a paper from the slurry. As a result, a sheet containing fine fibrous cellulose can be obtained. Among them, the manufacturing process of the sheet, the step of obtaining a slurry containing fine fibrous cellulose having a phosphite group or a substituent derived from the phosphite group and a basic component, and coating the slurry on a substrate It is preferable to include an engineering step.

  In the step of obtaining a slurry containing fine fibrous cellulose and a basic component, the pH of the slurry is preferably adjusted to 5.00 or more and 8.00 or less. That is, the step of obtaining a slurry containing fine fibrous cellulose and a basic component preferably includes a step of adding a basic component to the fine fibrous cellulose-containing slurry to adjust the pH to 5.00 or more and 8.00 or less. The addition amount of the base component can be appropriately changed depending on the pH of the fine fibrous cellulose-containing slurry and the type of the base component to be added, and is added so that the pH of the slurry containing the base component is 5.00 or more and 8.00 or less. Preferably. Thus, in the sheet manufacturing process, the basic component is added to the slurry used for sheet formation, and the pH of the slurry used for sheet formation is adjusted within the above range. Further, the addition of the basic component to the slurry used for forming the sheet also causes the sheet to contain the basic component. In addition, in the sheet forming step, it is preferable to adopt a condition in which the basic component added to the slurry remains in the sheet.

  When the sheet contains a resin, it is preferable to add a resin solution in the step of obtaining a slurry containing fine fibrous cellulose. The resin solution may be an aqueous solution in which a resin and water are mixed, or may be a solution in which a resin and an organic solvent are mixed. Further, after adding the resin solution, the slurry may be heated to enhance the dispersibility of the resin component.

<Coating process>
In the coating step, a sheet can be obtained by, for example, applying a slurry containing fine fibrous cellulose and a basic component onto a base material, and drying the formed sheet to peel off the formed sheet from the base material. Further, the sheet can be continuously produced by using the coating device and the long base material.

  The material of the base material used in the coating step is not particularly limited, but a material having higher wettability with the slurry may be capable of suppressing shrinkage of the sheet during drying, but the sheet formed after drying is easy. It is preferable to select one that can be peeled off. Of these, a resin film or plate or a metal film or plate is preferable, but not particularly limited. For example, resin film or plate of acrylic, polyethylene terephthalate, vinyl chloride, polystyrene, polyvinylidene chloride, etc., metal film or plate of aluminum, zinc, copper, iron plate, and those whose surface is oxidized, stainless film A board, a board, a brass film, or a board can be used.

  In the coating process, when the viscosity of the slurry is low and spreads on the base material, a damming frame should be fixed on the base material in order to obtain a sheet with a predetermined thickness and basis weight. May be. The damming frame is not particularly limited, but it is preferable to select, for example, a frame in which the edges of the sheet attached after drying can be easily peeled off. From this point of view, a resin plate or a metal plate is more preferable. In the present embodiment, for example, a resin plate such as an acrylic plate, a polyethylene terephthalate plate, a vinyl chloride plate, a polystyrene plate, or a polyvinylidene chloride plate, a metal plate such as an aluminum plate, a zinc plate, a copper plate, or an iron plate, and a surface thereof are used. It is possible to use those that have been subjected to oxidation treatment, those that have been molded from stainless steel plates, brass plates, and the like.

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

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

In the coating step, the slurry is used so that the finished basis weight of the sheet is preferably 10 g / m ² or more and 200 g / m ² or less, more preferably 20 g / m ² or more and 150 g / m ² or less. It is preferable to coat the material. By coating so that the basis weight is within the above range, a sheet having excellent strength can be obtained.

  As described above, the coating step includes a step of drying the slurry coated on the base material. The step of drying the slurry is not particularly limited, but is performed by, for example, a non-contact drying method, a method of drying while restraining the sheet, or a combination thereof. The non-contact drying method is not particularly limited, but for example, a method of heating and drying with hot air, infrared rays, far infrared rays or near infrared rays (heating drying method) or a method of drying in vacuum (vacuum drying method) is applied. can do. The heat drying method and the vacuum drying method may be combined, but the heat drying method is usually applied. Drying with infrared rays, far infrared rays, or near infrared rays is not particularly limited, but can be performed using, for example, an infrared device, a far infrared device, or a near infrared device. The heating temperature in the heating and drying method is not particularly limited, but is preferably 20 ° C. or higher and 150 ° C. or lower, and more preferably 25 ° C. or higher and 105 ° C. or lower. When the heating temperature is at least the above lower limit, the dispersion medium can be volatilized quickly. When the heating temperature is at most the above upper limit, it is possible to suppress the cost required for heating and suppress discoloration of fibrous cellulose due to heat.

<Papermaking process>
The papermaking process is performed by making a slurry from a papermaking machine. The paper machine used in the paper making step is not particularly limited, and examples thereof include a fourdrinier type, cylinder type, inclined type and the like continuous paper machine, or a multi-layered paper machine combining these. In the paper making step, a known paper making method such as hand making may be adopted.

  The papermaking step is performed by filtering the slurry with a wire and dehydrating it to obtain a wet paper sheet, and then pressing and drying this sheet. The filter cloth used for filtering and dehydrating the slurry is not particularly limited, but it is more preferable that, for example, fibrous cellulose does not pass through and the filtration rate does not become too slow. The filter cloth is not particularly limited, but for example, a sheet, a woven fabric, and a porous membrane made of an organic polymer are preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, and polytetrafluoroethylene (PTFE) are preferable. In the present embodiment, for example, a polytetrafluoroethylene porous film having a pore diameter of 0.1 μm or more and 20 μm or less, a polyethylene terephthalate or polyethylene woven fabric having a pore diameter of 0.1 μm or more and 20 μm or less, and the like can be mentioned.

  In the sheet-forming step, a method for producing a sheet from a slurry includes, for example, discharging a slurry containing fine fibrous cellulose and a basic component onto the upper surface of an endless belt, and squeezing a dispersion medium from the discharged slurry to form a web. This can be done using a manufacturing apparatus that includes a watering section and a drying section that dries the web to produce a sheet. An endless belt is arranged from the water squeezing section to the drying section, and the web generated in the water squeezing section is conveyed to the drying section while being placed on the endless belt.

  The dehydration method used in the papermaking step is not particularly limited, and examples thereof include a dehydration method commonly used in paper production. Among these, a method of dehydrating with a Fourdrinier, a cylinder, an inclined wire or the like, and then further dehydrating with a roll press is preferable. The drying method used in the papermaking step is not particularly limited, and examples thereof include the method used in paper production. Among these, a drying method using a cylinder dryer, a Yankee dryer, hot air drying, a near infrared heater, an infrared heater or the like is more preferable.

(Laminate)
The present invention may relate to a laminate having a structure in which another layer is further laminated on the above-mentioned sheet. Such other layer may be provided on both surfaces of the sheet, or may be provided only on one surface of the sheet. Examples of the other layer laminated on at least one surface of the sheet include a resin layer and an inorganic layer.

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

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

  The synthetic resin is preferably at least one selected from polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, polyimide resin, polystyrene resin and acrylic resin. Above all, the synthetic resin is preferably at least one selected from a polycarbonate resin and an acrylic resin, and more preferably a polycarbonate resin. The acrylic resin is preferably at least one selected from polyacrylonitrile and poly (meth) acrylate.

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

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

  An adhesive layer may be provided between the sheet and the resin layer, or the adhesive layer may not be provided and the sheet and the resin layer may be in direct contact with each other. When the adhesive layer is provided between the sheet and the resin layer, an acrylic resin can be given as an example of the adhesive forming the adhesive layer. Examples of adhesives other than acrylic resins include vinyl chloride resins, (meth) acrylic acid ester resins, styrene / acrylic acid ester copolymer resins, vinyl acetate resins, vinyl acetate / (meth) acrylic acid ester copolymers. Polymer resins, urethane resins, silicone resins, epoxy resins, ethylene / vinyl acetate copolymer resins, polyester resins, polyvinyl alcohol resins, ethylene vinyl alcohol copolymer resins and rubber emulsions such as SBR and NBR. To be

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

<Inorganic layer>
The substance constituting the inorganic layer is not particularly limited, but includes, for example, aluminum, silicon, magnesium, zinc, tin, nickel, titanium; oxides, carbides, nitrides, oxycarbides, oxynitrides, or oxycarbonitrides of these. Or a mixture thereof. From the viewpoint that high moisture resistance can be stably maintained, silicon oxide, silicon nitride, silicon oxycarbide, silicon oxynitride, silicon oxycarbonitride, aluminum oxide, aluminum nitride, aluminum oxycarbide, aluminum oxynitride, or these Mixtures are preferred.

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

  Further, as a method for forming the inorganic layer, an atomic layer deposition method (Atomic Layer Deposition, ALD) can also be adopted. The ALD method is a method of forming a thin film in atomic layer units by alternately supplying source gases of the respective elements forming the film to be formed to the surface on which the layer is formed. Although it has a drawback that the film formation rate is slow, it has an advantage over the plasma CVD method that it can cover even a complicated surface cleanly and can form a thin film with few defects. In addition, the ALD method has advantages that the film thickness can be controlled on the order of nanometers, and it is relatively easy to cover a wide surface. Further, in the ALD method, the use of plasma can be expected to improve the reaction rate, realize a low temperature process, and reduce unreacted gas.

(Molded body)
The present invention may relate to a molded product formed from the composition or sheet described above. The molded product formed from the composition or sheet of the present invention has an excellent flexural modulus, and is also excellent in strength and dimensional stability. In addition, the molded product formed from the composition or sheet of the present invention has excellent transparency.

(Use)
The composition or sheet of the present invention is suitable for use as a light-transmissive substrate for various display devices, various solar cells, and the like. Further, it is also suitable for applications such as substrates for electronic devices, separators for electrochemical devices, members for home appliances, window materials for various vehicles and buildings, interior materials, exterior materials, packaging materials, and the like. Furthermore, in addition to threads, filters, fabrics, cushioning materials, sponges, abrasives, etc., it is also suitable for the use of the sheet itself as a reinforcing material.

  The present invention will be described more specifically with reference to the following examples, but the scope of the present invention is not limited by the following examples.

[Example 1]
[Preparation of phosphite pulp]
As a raw material pulp, a softwood kraft pulp made by Oji Paper Co., Ltd. (solid content 93 mass%, basis weight 245 g / m ² sheet, disaggregated and measured in accordance with JIS P 8121, Canadian Standard Freeness (CSF) is 700 ml) It was used.

  This raw material pulp was subjected to phosphorus oxo oxidation treatment as follows. First, a mixed aqueous solution of phosphorous acid (phosphonic acid) and urea is added to 100 parts by mass of the raw material pulp (absolute dry mass) to form 33 parts by mass of phosphorous acid (phosphonic acid), 120 parts by mass of urea, and 150 parts of water. The pulp was prepared so as to be part by mass to obtain a chemical solution-impregnated pulp. Next, the obtained chemical liquid-impregnated pulp was heated with a hot air dryer at 165 ° C. for 250 seconds to introduce a phosphite group into the cellulose in the pulp to obtain a phosphorous acid pulp.

  Next, the obtained phosphorous acid pulp was washed. The washing treatment is carried out by repeating the operation of stirring the pulp dispersion obtained by pouring 10 L of ion-exchanged water to 100 g of phosphorous pulp (absolutely dry mass), and then filtering and dehydrating the pulp to uniformly disperse the pulp. Went by. When the electric conductivity of the filtrate became 100 μS / cm or less, the washing end point was set.

  Then, the washed phosphorous acid pulp was neutralized as follows. First, the washed phosphorous phosphite pulp is diluted with 10 L of ion-exchanged water, and a 1N sodium hydroxide aqueous solution is added little by little while stirring to give a phosphite pulp slurry having a pH of 12 or more and 13 or less. Obtained. Next, the phosphorous oxide pulp slurry was dehydrated to obtain a neutralized phosphorous oxide pulp. Then, the above-mentioned washing treatment was performed on the phosphorous oxide pulp after the neutralization treatment.

An infrared absorption spectrum of the phosphorous-oxidized pulp thus obtained was measured by using FT-IR. As a result, the absorption based on P = O of the phosphonic acid group, which is a tautomer of the phosphorous acid group, was observed near 1210 cm ^-1 , and the phosphorous acid group (phosphonic acid group) was added to the pulp. Was confirmed. Moreover, when the obtained phosphorous phosphite pulp was tested and analyzed by an X-ray diffractometer, two positions of 2θ = 14 ° or more and 17 ° or less and 2θ = 22 ° or more and 23 ° or less were determined. Was confirmed to have a typical peak, and it was confirmed to have a cellulose type I crystal.

[Disentanglement processing]
Ion-exchanged water was added to the obtained phosphorous oxide pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated twice with a wet atomizer (Starburst manufactured by Sugino Machine Ltd.) at a pressure of 200 MPa to obtain a fine fibrous cellulose dispersion liquid A containing fine fibrous cellulose. It was confirmed by X-ray diffraction that the fine fibrous cellulose maintained the cellulose type I crystal. The fiber width of the fine fibrous cellulose was measured with a transmission electron microscope, and it was 3 to 5 nm. Regarding the obtained fine fibrous cellulose, the phosphorus oxo acid group amount (first dissociated acid amount) measured by the measuring method described in [Measurement of phosphorus oxo acid group amount] described later was 1.51 mmol / g. . The total amount of dissociated acid was 1.54 mmol / g.

[Dissolution of polyethylene oxide]
Polyethylene oxide (manufactured by Sumitomo Seika Co., Ltd., PEO-18) was added to ion-exchanged water so as to be 1% by mass, and stirred for 1 hour to dissolve. Thus, a polyethylene oxide aqueous solution was obtained.

[Solution of sodium hydroxide]
Sodium hydroxide (granular) (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added to ion-exchanged water in an amount of 0.1 N, and the mixture was stirred for 15 minutes to dissolve. Thus, a sodium hydroxide solution was obtained.

[Preparation of sheet containing fine fibrous cellulose]
The fine fibrous cellulose dispersion A and the above polyethylene oxide aqueous solution were each diluted with ion-exchanged water so that the solid content concentration was 0.5% by mass. Next, 20 parts by mass of the diluted polyethylene oxide aqueous solution was added to 100 parts by mass of the diluted fine fibrous cellulose dispersion liquid to obtain a mixed liquid A. 400 g of the mixed solution A obtained by the above procedure was sampled, 0.47 g of the aqueous sodium hydroxide solution was added to obtain a coating solution having a adjusted pH. The pH of the coating liquid at this time was 7.02. Next, the coating liquid was weighed so that the finished basis weight of the sheet was 50 g / m ² , spread on a commercially available transparent acrylic plate, and dried in a constant temperature dryer at 50 ° C. In addition, a damming frame (internal dimensions 180 mm × 180 mm, height 50 mm) was placed on the acrylic plate so as to have a predetermined basis weight. The dried sheet was peeled from the acrylic plate to obtain a fine fibrous cellulose-containing sheet.

[Example 2]
[Dissolution of potassium hydroxide]
Ion-exchanged water was added to a 1 mol / L potassium hydroxide solution (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) to dilute it 10 times, and the mixture was stirred for 15 minutes. Thus, a 0.1N potassium hydroxide solution was obtained.

  Example 1 except that 0.54 g of an aqueous potassium hydroxide solution was added to the mixed solution A used in [Preparation of sheet containing fine fibrous cellulose] of Example 1 to obtain a pH adjusted coating solution. A sheet was obtained in the same manner. The pH of the coating liquid at this time was 7.00.

[Comparative Example 1]
A sheet was obtained in the same manner as in Example 1 except that the mixed solution A was formed into a sheet without adjusting the pH.

[Measurement]
[Measurement of phosphorus oxo acid group amount]
The phosphite group amount of the fine fibrous cellulose is a fiber prepared by diluting a fine fibrous cellulose dispersion liquid containing the target fine fibrous cellulose with ion-exchanged water to a content of 0.2% by mass. The granular cellulose-containing slurry was treated with an ion exchange resin and then titrated with alkali to measure.
The treatment with an ion exchange resin was carried out by adding 1/10 by volume of a strongly acidic ion exchange resin (Amber Jet 1024; Organo Co., Ltd., already conditioned) to the above-mentioned fibrous cellulose-containing slurry and performing a shaking treatment for 1 hour. , And the resin and the slurry were separated by pouring onto a mesh having an opening of 90 μm.
In addition, titration using an alkali measures the change in the pH value of the slurry while adding 10 μL of 0.1N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after the treatment with the ion exchange resin in 5 seconds. It was done by doing. The titration was performed 15 minutes before the start of titration while blowing nitrogen gas into the slurry. In this neutralization titration, two points at which the increment (the differential value of pH with respect to the amount of alkali added) is maximized are observed in the curve plotting the pH measured with respect to the amount of alkali added. Of these, the maximum point of the increment obtained first after adding alkali is called the first end point, and the maximum point of the increment obtained next is called the second end point (FIG. 1). The amount of alkali required from the start of titration to the first end point becomes equal to the amount of first dissociated acid in the slurry used for titration. Further, the amount of alkali required from the start of titration to the second end point becomes equal to the total amount of dissociated acid in the slurry used for titration. A value obtained by dividing the amount of alkali (mmol) required from the start of titration to the first end point by the solid content (g) in the slurry to be titrated was defined as the amount of phosphite group (mmol / g).

[PH measurement of sheet coating liquid]
The pH of the sheet coating liquid was measured with a calibrated handy pH meter (D-51S, manufactured by Horiba Ltd.).

[Surface pH]
The surface pH of the sheet was measured with a calibrated pH meter (F-53, manufactured by Horiba, Ltd.).

[Sheet haze]
The haze was measured using a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) according to JIS K 7136.

[Yellowness before and after heating the sheet]
According to JIS K 7373, the yellowness (YI) of the sheet before and after heating was measured using Color Cute i (manufactured by Suga Test Instruments Co., Ltd.). The yellowness after heating was measured after hot pressing the sheet at 180 ° C. and 0.5 MPa for 1 minute with a mini test press machine (made by Aida Engineering Co., Ltd.). In addition, ΔYI was calculated as the amount of change in yellowness from the following formula.
ΔYI = (yellowness of sheet after heating) − (yellowness of sheet before heating)
Furthermore, the YI increase rate was calculated by the following formula.
YI increase rate (%) = ΔYI / (yellowness of sheet before heating) × 100

  The sheets obtained in the examples had a low haze and a low YI increase rate, high transparency, and a yellow coloring was suppressed.

  On the other hand, since the sheet obtained in Comparative Example 1 did not contain a basic component, the YI increase rate was large.

Claims (9)

A composition comprising a fibrous cellulose having a fiber width of 1000 nm or less and a base component,
The composition is a sheet,
Fibrous cellulose has a substituent derived from a phosphite group or a phosphite group,
The base component is at least one selected from monovalent organic bases and monovalent inorganic bases,
Ri der solids content above 85 wt% of said composition,
A composition in which the pH of the surface of the sheet is 5.00 or more and 8.00 or less . The composition according to claim 1 , wherein the base component is a monovalent organic base. The composition according to claim 1 , wherein the base component is a monovalent inorganic base. The composition according to claim 3 , wherein the monovalent inorganic base is sodium hydroxide or potassium hydroxide. A composition according to any one of claims 1 to 4, further comprising a resin. The content of the base component relative to the total weight of said composition according to any one of claims 1 to 5, or less 8.0 wt% 0.05 wt%. The composition is a sheet, the composition according to any one of claims 1-6 haze of the sheet is less than 4.0%. The composition is a sheet,
A composition according to any one of claims. 1 to 7 YI increase rate calculated by the following equation is not more than 950%;
YI increase rate (%) = (yellowness of sheet after heating−yellowness of sheet before heating) / yellowness of sheet before heating × 100
In the above formula, the yellowness of the sheet after heating is the yellowness measured according to JIS K 7373 after hot pressing the sheet at 180 ° C. and 0.5 MPa for 1 minute, and the yellowness of the sheet before heating is It is the yellowness degree measured according to JIS K 7373 before hot pressing. A step of obtaining a slurry containing a fibrous cellulose having a fiber width of 1000 nm or less and having a phosphite group or a substituent derived from a phosphite group, and a basic component;
A method of manufacturing a sheet, comprising a coating step of coating the slurry on a substrate, or a papermaking step of papermaking the slurry,
The solid content of the sheet is 85 mass% or more,
The base component is at least one selected from monovalent organic bases and monovalent inorganic bases,
The step of obtaining a slurry containing the fibrous cellulose and a base component is a step of adding the base component to the slurry containing the fibrous cellulose, and a method for manufacturing a sheet.