JP2017065109A - Sheet and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine fiber-containing sheet and a laminate which achieve flexibility while suppressing yellowing caused by heating.SOLUTION: There are provided: a sheet which contains a fine fiber having an ionic substituent and an organic onium ion which is a counter ion of the ionic substituent, wherein the content of the organic onium ion is 0.10 mmol/g or more, the content of a phosphate group and a substituent derived from a phosphate group is 0.1 mmol/g or more based on the fine fiber, the fine fiber contains no carboxy group and substituent derived from a carboxy group or the content of the carboxy group and the substituent derived from a carboxy group is less than 0.1 mmol/g based on the fine fiber; and a laminate which comprises the sheet and at least one of an inorganic layer and an organic layer formed on at least one side of the sheet.SELECTED DRAWING: None

Description

  The present invention relates to a sheet and a laminate including fine fibers.

  In recent years, materials using reproducible natural fibers have attracted attention due to the substitution of petroleum resources and the growing environmental awareness. Among natural fibers, cellulose fibers having a fiber diameter of 10 to 50 μm, especially wood-derived cellulose fibers (pulp) have been widely used as paper products so far.

  As the cellulose fiber, fine fibrous cellulose having a fiber diameter of 1 μm or less is also known. Sheets and composites containing fine fibrous cellulose significantly increase the tensile strength because the contact points between fibers are remarkably increased. Moreover, transparency is greatly improved because the fiber width is shorter than the wavelength of visible light. As a method for producing fine fibers, there is known a method for introducing a substituent having electrostatic or steric functionality into a fiber raw material in order to easily refine the fiber raw material (defibration) (for example, Patent Documents 1 to 4).

  The fine fiber into which a functional substituent is introduced has been studied from various viewpoints. For example, in Patent Document 5, it is soluble in a wide range of organic solvents in view of the fact that the cellulose nanofibers having carboxylic acid groups are aggregated and precipitated when put into the same organic solvent as the material to be combined. Considered from the viewpoint of providing cellulose nanofibers. Specifically, an attempt has been made to disperse a carboxylate type group in an organic solvent after substituting the carboxylate type group of an amine having an organic group. Further, in Patent Document 6, it is possible to uniformly disperse in an organic solvent or resin, and to provide a dispersion containing fine cellulose fibers not containing metal ions in order to maintain water resistance and strength when formed into a sheet. Therefore, a fine cellulose fiber dispersion characterized by containing fine cellulose fibers and ammonia or organic alkali has been proposed. Furthermore, Patent Document 7 has been studied with the problem of being able to produce in a high yield, ensuring the stability of the slurry dispersion on the acidic side, and lowering the viscosity of the dispersion. Here, there has been proposed a fine fibrous cellulose into which two types of functional groups having a salt form with at least one selected from the group consisting of a cation, an ammonium ion, an aliphatic ammonium ion and an aromatic ammonium ion are introduced. .

JP 2008-308802 A JP 2010-254726 A Special table 2012-511596 gazette International Publication WO2013 / 073652 JP2012-21081A International Publication WO2011 / 111612 JP 2013-253200 A

  With respect to the fine fiber-containing sheet, flexibility may be required while suppressing yellowing due to heating.

  As a result of intensive studies, the present inventors have newly found that excellent flexibility can be realized while suppressing heat yellowing by treating fine fibers having a phosphate-derived group with organic onium ions. Completed the invention.

The present invention provides the following.
[1] a fine fiber having an ionic substituent;
An organic onium ion which is a counter ion of the ionic substituent;
Including
A sheet having an organic onium ion content of 0.10 mmol / g or more,
The content of a substituent derived from a phosphate group and a phosphate group is 0.1 mmol / g or more with respect to the fine fiber, and the fine fiber does not contain a carboxy group and a substituent derived from the carboxy group. Or the content of the substituent derived from the said carboxy group and a carboxy group is less than 0.1 mmol / g with respect to the said fine fiber.
[2] The sheet according to 1, wherein the organic onium ion has 4 or more carbon atoms.
[3] The sheet according to 1 or 2, wherein the density is 1.0 g / cm ³ or more.
[4] The sheet according to any one of 1 to 3, wherein the tensile elastic modulus at a temperature of 23 ° C. and a relative humidity of 50% is 3.5 GPa or less.
[5] The sheet according to any one of 1 to 4, wherein the pencil hardness is F or less.
[6] The sheet according to any one of 1 to 5, wherein the change in yellowing degree (ΔYI) is 70 or less.
[7] The sheet according to any one of 1 to 6,
A laminate comprising at least one of an inorganic layer and an organic layer formed on at least one side of the sheet.

  ADVANTAGE OF THE INVENTION According to this invention, the yellowing by heating is suppressed and the sheet | seat which has the outstanding softness | flexibility is provided.

FIG. 1 shows three regions in the substituent content measurement by the conductivity titration method.

  Values relating to the mass of fibers such as cellulose are based on the absolute dry mass (solid content), unless otherwise specified. The numerical range “X to Y” includes the values X and Y at both ends unless otherwise specified.

  The present invention includes a fine fiber having a phosphate-derived group as an ionic substituent and an organic onium ion which is a counter ion of the phosphate-derived group, and the content of the phosphate-derived group is constant. , A sheet containing no group derived from a carboxylic acid, or containing less than 0.1 mmol / g, and having an organic onium ion content of a certain value or more, a laminate using the sheet, and a method for producing them I will provide a.

1. Sheet containing fine fiber and organic onium ion [fine fiber having phosphoric acid-derived group]
<Fine fibers>
The sheet | seat of this invention contains the fine fiber which has group derived from phosphoric acid as an ionic substituent. Fine fibers having a phosphoric acid-derived group can be obtained by introducing an ionic substituent into a fiber raw material and performing a fine treatment. In the present invention, the fine fiber is, for example, a fiber having a fiber width of 1000 nm or less, and is preferably a natural fiber. Natural fibers are preferably polysaccharides because they are available in abundance, and more preferably cellulose, chitin, or chitosan because strength can be expected when formed into a sheet. A cellulose fiber is mentioned as a particularly preferable example of the natural fiber. In the following, the present invention, its embodiments and examples may be described by taking the case of using fine fibrous cellulose as an example, but those skilled in the art will use other types of fibers as appropriate for the description. It can be understood by applying to cases.

  The average fiber width of the fine fibers contained in the sheet of the present invention is not particularly limited as long as it is 1000 nm or less, but can be, for example, 1 nm or more, preferably 2 to 1000 nm, more preferably 2 to 500 nm, and still more preferably. 3-100 nm. When the average fiber width of the fine fibers is 1000 nm or less, the features (high transparency, high elastic modulus, low linear expansion coefficient, flexibility) as fine fibers are easily exhibited. On the other hand, when the average fiber width is 1 nm or more, the dissolution of molecules in water is suppressed, so that physical properties (strength, rigidity, dimensional stability) as a fine fiber are sufficiently expressed.

  In applications where the sheet is required to have relatively high transparency, if the average fiber width is 30 nm or less, it approaches 1/10 of the wavelength of visible light, and in the case of a laminate, refraction and scattering of visible light at the interface. There is a tendency that a product with high transparency is obtained. Therefore, the average fiber width is not particularly limited, but is preferably 2 to 30 nm, and more preferably 2 to 20 nm. A laminate obtained from such fine fibers generally has a high strength because it becomes a dense structure, and has high transparency because it scatters less visible light.

The average fiber width is measured as follows. A fine fiber-containing slurry having a concentration of 0.05 to 0.1% by mass is prepared, and the slurry is cast on a carbon film-coated grid subjected to a hydrophilization treatment to obtain a sample for TEM observation. When wide fibers are included, an SEM image of the surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, 20000 times, or 50000 times, depending on the width of the constituent fibers. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.
(1) One straight line X is drawn at an arbitrary location in the observation 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 that intersects with the straight line X and the straight line Y is visually read from the observation image that satisfies the above conditions. In this way, at least three sets of images of the surface portion that do not overlap each other are observed, and the width of the fiber intersecting with the straight lines X and Y is read for each image. Thus, at least 20 × 2 × 3 = 120 fiber widths are read. The average fiber width is an average value of the fiber widths read in this way.

  Although the fiber length of a fine fiber is not specifically limited, 0.1 micrometer or more is preferable. If the fiber length is 0.1 μm or more, it is preferable in that the tear strength of the sheet is sufficient when a sheet described later is manufactured. The fiber length can be obtained by image analysis of TEM, SEM, or AFM. The said fiber length is a fiber length which occupies 30 mass% or more of a fine fiber.

  The axial ratio of fibers (fiber length / fiber width) is not particularly limited, but is preferably in the range of 20 to 10,000. An axial ratio of 20 or more is preferable in that a fine fiber-containing sheet is easily formed during production. When the axial ratio is 10,000 or less, it is preferable in that the slurry viscosity at the time of sheet production becomes low.

<Group derived from phosphoric acid>
The fine fiber contained in the sheet of the present invention has an ionic substituent. The ionic substituent facilitates the refinement (defibration) of the fiber raw material in the production of the fine fiber-containing sheet. The ionic substituent includes at least an anionic substituent. Examples of the anionic substituent include a phosphate group or a substituent derived from a phosphate group (hereinafter, a phosphate group and a substituent derived from a phosphate group are also referred to as a phosphate-derived group), a carboxy group, or Substituents derived from carboxy groups (hereinafter, carboxy groups and substituents derived from carboxy groups are also referred to as carboxylic acid-derived groups), sulfate groups or substituent groups derived from sulfate groups (hereinafter referred to as sulfate groups and sulfate groups). The substituent derived from the above is also referred to as a group derived from sulfuric acid), a sulfonic acid group or a substituent derived from a sulfonic acid group (hereinafter, the substituent derived from a sulfonic acid group and a sulfonic acid group is referred to as a group derived from a sulfonic acid Also called). The phosphoric acid group is a divalent functional group equivalent to the phosphoric acid obtained by removing the hydroxyl group. Specifically, it is a group represented by —PO ₃ H ₂ . The substituent derived from the phosphate group includes a substituent such as a group obtained by polycondensation of a phosphate group, a salt of a phosphate group, and a phosphate ester group. Moreover, the substituent derived from a phosphoric acid group or a phosphoric acid group may be represented by the following formula (1).

In formula (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (n = 1 to n) and α ′ are each independently R or OR is represented. R represents 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. , An aromatic group, or a derivative group thereof; β is a monovalent or higher cation composed of an organic substance or an inorganic substance.

The fine fiber contained in the sheet of the present invention has at least a group derived from phosphoric acid.
The amount of the phosphoric acid-derived group contained in the sheet is not particularly limited as long as it can be efficiently miniaturized, but can be 0.1 mmol / g or more based on the sheet or fine fiber. It may be 0.5 mmol / g, or 1.0 mmol / g or more. Although the upper limit of the group derived from phosphoric acid is not particularly limited, it can be 5.0 mmol / g or less with respect to the sheet or fine fiber, for example, regardless of the lower limit. g or less, or 2.0 mmol / g or less.

  While the sheet | seat of this invention has group derived from phosphoric acid, it does not contain the group derived from carboxylic acid, or contains a trace amount. When the sheet contains a small amount of a group derived from carboxylic acid, the content is not particularly limited as long as the target properties are not impaired in the sheet, but it can be less than 0.1 mmol / g with respect to the sheet or fine fiber. . It may be less than 0.07 mmol / g, or less than 0.05 mmol / g. The lower limit of the group derived from the carboxylic acid is not particularly limited, but can be 0.0005 mmol / g or more with respect to the sheet or fine fiber, for example, regardless of the upper limit. It is good also as g.

The content (mmol / g) of the ionic substituent in the sheet can be measured as follows using a fluorescent X-ray analysis method.
First, for preparing a calibration curve, a sheet having the same fine fiber as that used for the measurement target sheet and having a known ionic substituent content (mmol / g) is prepared, and this is determined by fluorescent X-ray analysis. The X-ray intensity of the sample is measured. The element to be measured is an element that is included in the ionic substituent but is not included in the fine fiber (for example, a phosphorus atom when the ionic substituent is a group derived from phosphoric acid), or a counter ion of the ionic substituent Is an element that is contained in but not in fine fibers. If necessary, the measurement target sheet can be used for measurement after exchanging the counter ion of the ionic substituent with another counter ion containing an element not included in the fine fiber. For example, when the ionic substituent is a group derived from a carboxylic acid, the counter ion can be exchanged for sodium ion and then used for measurement. In this case, the measurement element is sodium ion. Next, a calibration curve is prepared based on the X-ray intensity obtained thereby and the known ionic substituent content.
On the other hand, the X-ray intensity of the measurement target sheet is measured by fluorescent X-ray analysis. Next, the content (mmol / g) of the ionic substituent of the measurement target sheet is determined from the X-ray intensity obtained thereby and the calibration curve. The determined value can be expressed as the content of ionic substituents on the sheet or fine fiber.

[Organic onium ion]
<Types of organic onium ions>
The sheet of the present invention contains an organic onium ion represented by the following formula (2) as a counter ion such as a group derived from phosphoric acid.

式（２）

Formula (2)

In the formula:
M is a nitrogen atom or a phosphorus atom;
At least one of R _{1 to} R ₄ is an organic group that may contain a hetero atom, and the remainder is a hydrogen atom. The number of carbons in the organic group (when having a plurality of organic groups, the total number of carbons) is 1 or more and is not particularly limited as long as the desired effect is exhibited, but is preferably 4 or more, and 8 or more. More preferably, it is more preferably 16 or more. This is because a large carbon number and a certain amount of bulk are effective. R _{1 to} R ₄ may be the same or different from each other, but are preferably the same or the same size group. This is because it is considered that the effect closer to the spherical shape is greater than the linear shape.

  Such an organic onium ion is preferably a tetraalkylonium ion, for example, and more preferably contains at least one of a tetraalkylammonium ion and a tetraalkylphosphonium ion. Examples of tetraalkylammonium ions include tetramethylammonium ion, tetraethylammonium ion, tetrapropylammonium ion, tetrabutylammonium ion, tetrapentylammonium ion, tetrahexylammonium ion, tetraheptylammonium ion, tributylmethylammonium ion, lauryltrimethylammonium ion. Ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, octyldimethylethylammonium ion, lauryldimethylethylammonium ion, didecyldimethylammonium ion, lauryldimethylbenzylammonium ion, and tributylbenzylammonium ion. Examples of tetraalkylphosphonium ions include tetramethylphosphonium ions, tetraethylphosphonium ions, tetrapropylphosphonium ions, tetrabutylphosphonium ions, and lauryltrimethylphosphonium ions. In addition, as tetrapropyl onium ion and tetrabutyl onium ion, it is particularly preferable to use tetra n-propyl onium ion and tetra n-butyl onium ion, respectively.

<Content of organic onium ion>
Although the sheet | seat of this invention contains organic onium ion, the content is 0.10 mmol / g or more with respect to a sheet | seat. Preferably it is 0.20 mmol / g or more, More preferably, it exceeds 0.40 mmol / g, More preferably, it is 1.0 mmol / g or more. This is because even with such an amount, it is considered that hydrogen bonds between groups derived from phosphoric acid can be blocked to such an extent that aggregation does not occur. The upper limit value of the content of the organic onium ion in the sheet is not particularly limited, but whatever the lower limit value is, for example, 10.0 mmol / g or less, preferably 5.0 mmol / g or less with respect to the sheet. More preferably, it is 3.0 mmol / g or less. In addition, regarding the fiber or the sheet in the present invention, when it is referred to as the content of organic onium ions, unless otherwise specified, regardless of whether or not an ion pair is formed with a phosphate-derived group on the sheet, The value measured by the measurement method described.

The content (mmol / g) of organic ions in the sheet can be measured using, for example, chemiluminescence, infrared spectroscopy, time-of-flight mass spectrometry, or fluorescent X-ray analysis.
When nitrogen is contained in the organic ions, the concentration of nitrogen atoms in the sheet can be measured by, for example, a trace nitrogen analyzer using a chemiluminescence method. At this time, the nitrogen atom concentration of the fine fiber-containing sheet not treated with organic ions is also measured, and the nitrogen atom concentration derived from organic ions is reduced by subtracting the value from the nitrogen atom concentration of the fine fiber-containing sheet to be measured. And the organic ion content can be calculated. In addition, for example, when a group derived from phosphoric acid is included as an ionic substituent, an organic ion is not imparted by performing a treatment for 2 hours at 180 ° C. using glycerin by a polyhydric alcohol boiling method described later. It is thought that it can be handled in the same manner as the fine fiber-containing sheet. In the case of containing an ionic substituent other than a phosphate-derived group, in the counter ion exchange described later, in the case of an anionic substituent, the pH 1 treatment liquid, and in the case of a cationic substituent, the pH 14 treatment liquid, respectively. It is thought that it can treat like the fine fiber containing sheet | seat which has not provided the organic ion by immersing for 2 hours.

  When a phosphorus atom is contained in the organic ion, it is possible to calculate the phosphorus atom concentration derived from the organic ion in the sheet using, for example, a fluorescent X-ray analysis method as follows. First, X-ray fluorescence analysis is performed on the measurement target sheet, and the phosphorus atom concentration in the measurement target sheet is calculated based on the characteristic X-ray intensity of phosphorus atoms and the calibration curve for the amount of phosphorus introduced. calculate. Next, the phosphorus atom concentration of the fine fiber-containing sheet that does not contain organic ions is also measured, and the phosphorus atom concentration derived from organic ions is obtained by subtracting the value from the phosphorus atom concentration of the fine fiber-containing sheet to be measured. The content can be calculated. The fine fiber-containing sheet not containing organic ions is, for example, a counter ion exchange described later with respect to the sheet to be measured, in a treatment solution having a pH of 1 in the case of an anionic substituent, and pH 14 in the case of a cationic substituent. It is thought that it can treat like the fine fiber containing sheet | seat which has not provided the organic ion by immersing in each processing liquid for 2 hours.

When the organic onium ion includes an element other than nitrogen and an element considered not to exist in the fine fiber-containing sheet, the content of the organic onium ion in the sheet is determined using the following fluorescent X-ray analysis method. Can be measured as follows.
First, to prepare a calibration curve, a sample having a composition and form similar to those of the measurement target sheet (for example, using filter paper) and having a known analytical element content (mmol / g) is prepared, and fluorescence is prepared. The X-ray intensity of the sample is measured by X-ray analysis. Here, the element considered to be contained in the organic onium ion but not present in the fine fiber-containing sheet is the analytical element. Then, a calibration curve is created based on the X-ray intensity obtained thereby and the known content of the analytical element. Next, the X-ray intensity of the measurement target sheet is measured by fluorescent X-ray analysis. And the content (mmol / g) of the analytical element in a measuring object sheet | seat is computed from the X-ray intensity obtained by this, and the said calibration curve.

[Sheet characteristics]
The sheet of the present invention has the following characteristics.

<Density>
The density of a sheet refers to a value (g / cm ³ ) obtained from the thickness and mass of a sheet after conditioning a 100 mm square sheet under conditions of 23 ° C. and 50% RH for 24 hours. The density of the sheet of the present invention can be appropriately determined according to the use and the like, but can be 0.1 to 7.0 g / cm ³ from the viewpoint of strength and transparency, and 0.5 to 5 it is preferably .0g / cm ^3, more preferably 1.0 to 3.0 g / cm ^3. In the present embodiment, the density of the sheet can be set to 1.50 g / cm ³ or less, for example.

<Wrinkles / cracks>
Wrinkles and cracks during sheet production can be evaluated by the following method. When forming a dispersion of fine fibers into a sheet, a total of 81 squares of 9 × 9 in width is written on the back surface of the acrylic plate in accordance with the size of each 180 mm damming metal frame. The fine fiber-containing sheet is observed from above with the acrylic plate attached to the acrylic plate, and the masses where wrinkles and cracks are generated are counted. Next, it is calculated what percentage of the total number of cells where wrinkles and cracks occur.
When the sheet of the present invention is evaluated by this method, the proportion of mass in which wrinkles and cracks are generated is less than 20%.

<Total light transmittance>
The total light transmittance of the sheet refers to a value measured using a haze meter in accordance with JIS standard K7361. The sheet of the present invention has high transparency, and the total light transmittance thereof is 80% or more, preferably 85% or more, and more preferably 88% or more.

<Haze value>
The haze value of the sheet refers to a value measured using a haze meter in accordance with JIS standard K7136. The sheet of the present invention has high transparency, and its haze value is 40.0% or less, preferably 35.0% or less, and more preferably 20.0% or less.

<Tensile modulus>
The tensile elastic modulus of the sheet refers to a value measured at a temperature of 23 ° C. and a relative humidity of 50% using a tensile tester in accordance with JIS K 7127. The sheet obtained by the present invention is excellent in flexibility. Specifically, the tensile elastic modulus of the sheet of the present invention is 3.5 GPa or less, preferably 3.2 GPa or less, and more preferably 3.0 GPa or less. This is because if it is less than this value, flexibility as a packaging material can be realized. The lower limit value is, for example, 0.1 GPa or less, or 0.5 GPa or more from the viewpoint of maintaining a certain level of strength.

<Yellowness change>
The yellowing degree change (ΔYI) of the sheet is expressed by the following formula: ΔYI = YI ₂ −YI ₁
However, YI ₁ indicates the yellowness before vacuum drying at 200 ° C. for 4 hours, and YI ₂ indicates the yellowness after vacuum drying at 200 ° C. for 4 hours. Yellowness refers to a value measured according to JIS standard K7373. In the sheet of the present invention, the yellowing degree change (ΔYI) is suppressed. The yellowing degree change (ΔYI) of the sheet of the present invention is, for example, 70 or less, preferably 60 or less, and more preferably 55 or less. Thus, in the sheet | seat of this invention, it is thought that it is based on the following factors that the yellowing by heating is suppressed, implement | achieving a softness | flexibility. When forming into a sheet, an appropriate organic onium ion is applied as a counter ion to the group derived from phosphoric acid (the aggregation of fine fibers due to the group derived from phosphoric acid observed in the drying step during sheeting can be prevented. ). Further, the type of group on the fine fiber, the amount thereof, and the type of organic onium ion contained in the sheet, and the amount thereof are appropriately selected. Thus, it is presumed that appropriately selecting the production conditions of the fine fibers and the sheet using the fine fibers contributes to imparting flexibility and suppressing yellowing due to heating. These are also considered to affect the density, total light transmittance, haze, yellowness change, etc. of the sheet.

<Pencil hardness>
The pencil hardness is a value measured according to JIS standard K5600. However, the load applied to the sample is 500 g. The sheet of the present invention has high flexibility, and its pencil hardness is F or less, preferably HB or less, and more preferably B or less. This is because such a range is suitable for use as a flexible package.

<Molding followability>
Molding flexibility can be evaluated by the following method. The fine fiber-containing sheet is cut into a 150 mm square, and packaged so as to wrap the entire wooden columnar molded body having a diameter of 50 mm and a height of 60 mm. Next, the cylindrical molded body is visually observed from above. Visual observation is performed from the viewpoint of the presence or absence of a gap between the cylindrical molded body and the sheet and the cracking of the sheet.
In the sheet of the present invention, when the molding followability is evaluated, no voids are observed between the cylindrical molded body and the fine fibrous cellulose sheet, and no cracks are observed in the fine fibrous cellulose sheet.

2. Manufacturing method of sheet The manufacturing method of the sheet of the present invention,
(1) introducing an ionic substituent into the fiber raw material to obtain an ionic substituent-introduced fiber;
(2) a step of refining the ionic substituent-introduced fiber to obtain an ionic substituent-introduced fine fiber, and further before or after step (2),
A step of treating the ionic substituent with an organic onium ion, and (3) a step of preparing a sheet from the ionic substituent-introduced fine fiber treated with the organic onium ion;
including.

[Step (1): Step of obtaining an ionic substituent-introduced fiber by introducing an ionic substituent into a fiber raw material]
<Fiber raw material>
The fine fiber having an ionic substituent can be obtained by introducing an ionic substituent into a fiber raw material and performing a fine treatment. The fiber raw material used in the step (1) is a natural fiber that can be obtained in abundance, preferably cellulose, chitin or chitosan, more preferably cellulose. As the fiber raw material, it is preferable to use pulp because it is easily available and inexpensive. Among the pulps, wood pulp containing cellulose is preferable in terms of availability. Among wood pulps, chemical pulp has a large cellulose ratio, so the yield of fine cellulose fibers is high when fibers are refined, and cellulose fibers in the pulp are small, and long fine fiber fibers with a large axial ratio are obtained. However, it is not particularly limited. Of these, kraft pulp and sulfite pulp are most preferably selected, but are not particularly limited.

<Introduction of ionic substituent>
An ionic substituent is introduced into the fiber raw material. A method for introducing a substituent into the fiber is not particularly limited, and examples thereof include treatment with a compound capable of forming a covalent bond with a functional group in the fiber.

  Treatment with a compound capable of forming a covalent bond with a functional group in the fiber introduces the above substituents into the fiber raw material by mixing the fiber raw material in a dry or wet state with a compound that reacts with the fiber raw material. Can be implemented. In order to promote the reaction at the time of introduction, a heating method is particularly effective. The heat treatment temperature for introducing the substituent is not particularly limited, but is preferably a temperature range in which thermal decomposition or hydrolysis of the fiber raw material hardly occurs. For example, it is preferable that it is 250 degrees C or less from a viewpoint of the thermal decomposition temperature of a fiber, and it is preferable to heat-process at 100-170 degreeC from a viewpoint of suppressing hydrolysis of a fiber.

  The compound that reacts with the fiber raw material is not particularly limited as long as fine fibers can be obtained and an ionic substituent is introduced. For example, it is at least one selected from the group consisting of phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, or salts or esters thereof. Among these, a compound having a phosphate-derived group is preferable because it is low-cost, easy to handle, and can further improve the refinement (defibration) efficiency by introducing a phosphate-derived group into the fiber raw material. There is no particular limitation.

The compound having a phosphoric acid-derived group is not particularly limited, but phosphoric acid, lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, lithium polyphosphate Can be mentioned. Furthermore, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate and sodium polyphosphate which are sodium salts of phosphoric acid are mentioned. Furthermore, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate which are potassium salts of phosphoric acid are mentioned. Further examples include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate, which are ammonium salts of phosphoric acid.
Among these, phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, and ammonium salt of phosphoric acid are preferable from the viewpoint of high efficiency of introduction of a group derived from phosphoric acid and easy industrial application. Sodium dihydrogen and disodium hydrogen phosphate are more preferable, but not particularly limited.

  In addition, the compound is preferably used as an aqueous solution because of the uniformity of the reaction and the introduction efficiency of the group derived from phosphoric acid, but it is not particularly limited. The pH of the aqueous solution of the compound is not particularly limited, but is preferably 7 or less because of the high efficiency of introducing a phosphoric acid-derived group. Although pH 3-7 is especially preferable from a viewpoint of suppressing hydrolysis of a fiber, it is not specifically limited.

  When a compound having a carboxylic acid-derived group is used as the compound that reacts with the fiber raw material, the compound having a carboxylic acid-derived group, an acid anhydride of the compound having a carboxylic acid-derived group, and the like are not particularly limited. At least one selected from the group consisting of

  The compound having a carboxylic acid-derived group is not particularly limited, but a dicarboxylic acid compound such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid or itaconic acid, or a tricarboxylic acid compound such as citric acid or aconitic acid. Is mentioned.

  The acid anhydride of the compound having a carboxylic acid-derived group is not particularly limited, but acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, itaconic anhydride, etc. Things.

  The derivative of the compound having a carboxylic acid-derived group is not particularly limited, and examples thereof include an acid anhydride imidized compound having a carboxylic acid-derived group and an acid anhydride derivative of a compound having a carboxylic acid-derived group. . The acid anhydride imidized compound having a carboxylic acid-derived group is not particularly limited, and examples thereof include imidized dicarboxylic acid compounds such as maleimide, succinimide, and phthalimide.

  The acid anhydride derivative of the compound having a carboxylic acid-derived group is not particularly limited. For example, at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxylic acid-derived group, such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, diphenylmaleic acid anhydride, are substituted (for example, alkyl group, And those substituted with a phenyl group or the like.

  Among the compounds having a group derived from a carboxylic acid, maleic anhydride, succinic anhydride, and phthalic anhydride are preferred because they are easily applied industrially and easily gasified, but are not particularly limited.

  When a compound having a group derived from sulfuric acid is used as the compound that reacts with the fiber raw material, it is not particularly limited, but it is at least one selected from the group consisting of sulfuric anhydride, sulfuric acid and salts and esters thereof. Among these, sulfuric acid is preferred, but is not particularly limited because it is low in cost and can further improve the refinement (defibration) efficiency by introducing a sulfate group into the fiber raw material.

  By introducing a substituent into the fiber raw material, the dispersibility of the fiber in the solution is improved, and the refinement (defibration) efficiency can be increased.

The introduction amount of the ionic substituent is not particularly limited as long as sufficient miniaturization can be performed, but it is determined in consideration of the content of the bivalent or higher metal as the sheet and the introduction amount of the substituent as described later. be able to. When the sheet | seat of this invention contains the fine fiber which has an anionic substituent, 0.005 (alpha) -0.11 (alpha) are preferable per 1g (mass) of fibers, and the introduction amount of a substituent is 0.00. 01α to 0.08α is more preferable. If the introduction amount of the substituent is 0.005α or more, the fiber raw material can be easily refined (defibration). If the introduction amount of the substituent is 0.11α or less, dissolution of the fiber can be suppressed. However, (alpha) is the quantity (unit: mmol / g) by which the functional group which the compound which reacts with a fiber material can react, for example, a hydroxyl group and an amino group, is contained per 1 g of fiber materials.
In addition, the measurement of the introduction amount (titration method) of substituents on the fiber surface can be performed by the following method, unless otherwise specified:
A fine fiber-containing slurry containing about 0.04 g of solid content in an absolutely dry mass is collected and diluted to about 50 g using ion-exchanged water. While stirring this solution, the change in the value of electrical conductivity when a 0.01N sodium hydroxide aqueous solution was added dropwise was measured, and the amount of 0.01N sodium hydroxide aqueous solution added when the value was minimized was measured. The amount dropped at the titration end point. The substituent content X on the cellulose surface is expressed as X (mmol / g) = 0.01 (mol / l) × V (ml) / W (g). Here, V: A dripping amount (ml) of 0.01N sodium hydroxide aqueous solution, W: Solid content (g) contained in the slurry containing fine cellulose fibers.

  When the introduced substituent is at least one selected from the group consisting of a phosphoric acid-derived group, a carboxylic acid-derived group and a sulfuric acid-derived group, the amount of substituent introduction is not particularly limited, but 0 0.001 to 5.0 mmol / g. It may be 0.05 to 4.0 mmol / g, or 0.1 to 2.0 mmol / g.

  By introducing a substituent into the fiber raw material, the dispersibility of the fiber in the solution can be improved, and the fibrillation efficiency can be increased.

<Acid treatment>
If necessary, after the step of introducing an ionic substituent into the fiber raw material to obtain an ionic substituent-introduced fiber, before the step of treating the ionic substituent with an organic onium ion, an acid treatment is performed. It can be carried out. The acid used for the acid treatment is preferably an acid having an ionization degree equal to or higher than the introduced ionic substituent, but is not particularly limited. The acid treatment can be performed using, for example, one or more selected from the group consisting of hydrochloric acid, nitric acid and sulfuric acid. By such treatment, the introduced ionic substituent becomes sufficiently H-type, and the organic onium ion can be more easily added to the ionic substituent.

  The acid treatment method can be performed, for example, by immersing the ionic substituent-introduced fiber in an acid solution. As the solvent in the acid solution, at least one of water and an organic solvent can be used. A polar one (polar organic solvent such as water or alcohol) is preferable, and an aqueous solvent containing water is more preferable. A particularly preferred example of the acid solution is hydrochloric acid.

  In the case of acid treatment, the pH of the acid solution at 25 ° C. can be appropriately determined, but is preferably 4 or less, more preferably 3.5 or less, and even more preferably 3 or less.

  In order to reduce the amount of acid used, the fibers having ionic substituents may be washed before the acid treatment. For washing, at least one of water and an organic solvent can be used. Further, after the acid treatment, the group-introduced fiber having a treated ionic substituent may be washed with at least one of water and an organic solvent. In either case, the washing operation can be repeated.

[Step (2): Step of obtaining phosphoric acid-derived group-introduced fine fibers by refining phosphoric acid-derived group-introducing fibers]
During the refinement (defibration) process, the fibers are dispersed in a solvent. The type of the solvent is not particularly limited as long as it can be appropriately refined (sometimes referred to as defibration), but an aqueous solvent (water or a mixture of water and an organic solvent) can be used. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and tbutyl alcohol. Further, ketones such as acetone and methyl ethyl ketone (MEK), ethers such as diethyl ether and tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc) and the like can be mentioned. Only one organic solvent may be used, or two or more organic solvents may be used.

  The dispersion concentration is preferably from 0.1 to 20% by mass, and more preferably from 0.5 to 10% by mass. This is because if the content is equal to or higher than the lower limit, the processing efficiency is improved, and if the content is equal to or lower than the upper limit, blockage in the defibrating apparatus can be prevented.

  The defibrating apparatus is not particularly limited. Examples include a high-speed defibrator, a grinder (stone mortar-type pulverizer), a high-pressure homogenizer, an ultra-high-pressure homogenizer, a CLEARMIX, a high-pressure collision-type pulverizer, a ball mill, a bead mill, a disk refiner, and a conical refiner. In addition, a wet pulverizing apparatus such as a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, and a beater can be used as appropriate.

  The refinement process is performed until fibers having a desired average fiber diameter are obtained. A fine fiber dispersion (slurry) is obtained by the refining treatment. The obtained fine fiber dispersion may contain fibers having a fiber width of more than 1000 nm, but preferably does not contain fibers having a fiber width of more than 1000 nm. The density | concentration of a fine fiber here is 0.1-20 mass%, for example, and may be 0.5-10 mass%.

[Process for treating phosphoric acid-derived groups with organic onium ions]
In the present invention, the group derived from phosphoric acid is treated with an organic onium ion before the step (3).

  This step may be performed before the miniaturization treatment in step (2). Specifically, organic onium ions are introduced into the fiber dispersion before the refinement treatment. This aspect has an advantage that the washing load of the organic onium ions is low, and surplus organic onium ions can be sufficiently removed by washing. In addition, since excess organic onium ions can be sufficiently removed, there is an advantage that the transparency of the obtained sheet becomes higher.

  This process can also be performed after the miniaturization process of a process (2). Specifically, organic onium ions are introduced into the fine fiber dispersion after the refinement treatment. According to this embodiment, various kinds of fine organic onium ions can be introduced.

  The treatment method using organic onium ions is not particularly limited as long as the group derived from phosphoric acid of the fiber and the organic onium ions can form an ion pair. Typically, it is carried out by adding an aqueous solution of a compound which is an organic onium ion source to a dispersion of fibers or fine fibers. The concentration of the aqueous solution used depends on the solubility of the compound in water, but can be 0.1% by mass or more, preferably 1.0% by mass or more, and more preferably 5.0% by mass or more. It is more preferable. The upper limit value may be determined from an economical viewpoint, but is preferably 40% by mass or less, and more preferably 35% by mass or less from the viewpoint of ensuring the transparency of the sheet. The amount of the organic onium ion used is preferably an amount capable of forming ion pairs with many of the phosphate-derived groups introduced into the sheet. For example, at least 50% or more, preferably 60% or more, more preferably 70% or more, more preferably 80% or more, and further preferably 90% or more of the phosphoric acid-derived group of the introduced substituent group forms an ion pair. It can be used in the possible amount.

  After treatment with organic onium ions, washing can be performed as necessary. Washing can be performed with water or an aqueous solvent, preferably water.

  By treatment with organic onium ions, it is considered that organic onium ions and ionic substituents on the fibers form ion pairs, and aggregation of fine fibers during sheet formation is suppressed. As a result, the occurrence of wrinkling and cracking of the sheet is considered to be suppressed. Furthermore, it is considered that the sheet can be dried at a higher temperature and in a shorter time.

[Step (3): Step of preparing sheet from phosphoric acid-derived group-introduced fine fibers treated with organic onium ions]
A sheet is prepared from a dispersion (slurry) of fine fibers obtained by the refinement treatment. The method for preparing the sheet is not particularly limited, but can typically be based on the following papermaking method, coating method, or the like.

<Papermaking method>
In addition to continuous paper machines such as long-mesh type, circular net type, and inclined type, which use fine fiber-containing slurry for ordinary paper making, multi-layered paper making machines combining these, and well-known paper making methods such as hand-making Paper is made and can be made into a sheet in the same manner as ordinary paper. That is, it is possible to obtain a sheet by filtering and dewatering the fine fiber-containing slurry on a wire to obtain a wet paper sheet, followed by pressing and drying. The concentration of the slurry is not particularly limited, but is preferably 0.05 to 5% by mass. If the concentration is too low, filtration takes a long time. Conversely, if the concentration is too high, a uniform sheet cannot be obtained, which is not preferable. When the slurry is filtered and dehydrated, the filter cloth at the time of filtration is not particularly limited, but it is important that the fine fibers do not pass and the filtration rate is not too slow. Although it does not specifically limit as such a filter cloth, The sheet | seat, fabric, and porous film which consist of organic polymers are preferable. The organic polymer is not particularly limited, but non-cellulosic organic polymers such as polyethylene terephthalate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and the like are preferable. Specific examples include a porous film of polytetrafluoroethylene having a pore diameter of 0.1 to 20 μm, for example, 1 μm, and polyethylene terephthalate or polyethylene fabric having a pore diameter of 0.1 to 20 μm, for example, 1 μm, but are not particularly limited.

<Coating method>
The coating method is a method of obtaining a sheet by coating a fine fiber-containing slurry on a base material and drying the slurry to peel the fine fiber-containing layer formed from the base material. By using a coating apparatus and a long base material, sheets can be continuously produced. The quality of the base material is not particularly limited, but the one having higher wettability to the fine fiber-containing slurry may be able to suppress the shrinkage of the sheet during drying, but the sheet formed after drying is more easily peeled off It is preferable to select what can be done. Among them, a resin plate or a metal plate is preferable, but is not particularly limited. Among them, suitable ones are preferably used alone or laminated. For example, resin plates such as acrylic plates, polyethylene terephthalate plates, vinyl chloride plates, polystyrene plates, polyvinylidene chloride plates, metal plates such as aluminum plates, zinc plates, copper plates, iron plates, etc., and those whose surfaces are oxidized, stainless steel Although a board, a brass board, etc. can be used, it is not specifically limited. In order to apply the fine fiber-containing slurry onto the base material, various coaters that can apply a predetermined amount of slurry to the base material may be used. Although not particularly limited, for example, a roll coater, a gravure coater, a die coater, a curtain coater, a spray coater, a blade coater, a rod coater, an air doctor coater, etc. can be used, among which a die coater, curtain coater, spray coater, air doctor coater can be used. A coating method such as the above is effective for uniform coating. As will be described later, when a sheet is used as a laminate, it may not be necessary to peel off the substrate.

<Sheet thickness>
The thickness of the sheet to be prepared is not particularly limited, and can be appropriately determined according to the application. Based on the finished basis weight or thickness of the sheet, the amount of slurry is measured, and papermaking or coating is performed. Can do.

<Dehydration and drying>
After papermaking or coating, if necessary, at least one of dehydration and drying is performed to form a sheet. Although it does not specifically limit as a dehydration method, The dehydration method normally used by manufacture of paper is mentioned, The method of dehydrating with a roll press after dehydrating with a long net, a circular net, an inclined wire, etc. is preferable. Further, the drying method is not particularly limited, and examples thereof include methods used in paper production. For example, methods such as a cylinder dryer, a Yankee dryer, hot air drying, and an infrared heater are preferable.

  Although it does not specifically limit as a drying method, Either a non-contact drying method or the method of drying while restraining a sheet | seat may be sufficient, and these may be combined.

  The non-contact drying method is not particularly limited, but a method of drying by heating 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. Although the heat drying method and the vacuum drying method may be combined, the heat drying method is usually applied. Although drying by 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, it is not particularly limited. Although the heating temperature in a heat drying method is not specifically limited, It is preferable to set it as 40-120 degreeC, and it is more preferable to set it as 40-105 degreeC. If the heating temperature is at least the lower limit value, the dispersion medium can be volatilized quickly, and if it is at most the upper limit value, the cost required for heating and the discoloration due to the heat of the fine fibers can be suppressed.

(Other fibers)
In preparing the sheet, although not particularly limited, the sheet can be prepared by mixing at least one kind of the fine fibers and fibers other than the fine fibers (hereinafter referred to as “additional fibers”). Examples of the additional fiber include inorganic fiber, organic fiber, synthetic fiber, semi-synthetic fiber, and recycled fiber, but are not particularly limited. Examples of inorganic fibers include, but are not limited to, glass fibers, rock fibers, and metal fibers. Examples of organic fibers include, but are not limited to, fibers derived from natural products such as cellulose, carbon fibers, pulp, chitin, and chitosan. Examples of synthetic fibers include, but are not limited to, nylon, vinylon, vinylidene, polyester, polyolefin (for example, polyethylene, polypropylene, etc.), polyurethane, acrylic, polyvinyl chloride, aramid, and the like. Semi-synthetic fibers include but are not limited to acetate, triacetate, promix and the like. Examples of the regenerated fiber include, but are not limited to, rayon, cupra, polynosic rayon, lyocell, and tencel. The additional fibers can be subjected to treatment such as chemical treatment and defibration treatment as necessary.

  Although mixing is not specifically limited, For example, before papermaking or coating, it can be performed by adding other fibers to the fine fiber-containing slurry. When the additional fiber is subjected to chemical treatment, defibrating treatment, etc., it can be mixed with fine fibers and then subjected to chemical treatment, defibrating treatment, etc., and the additional fiber can be chemically treated, defibrated. It can also be mixed with fine fibers after being treated. Mixing those having the same average fiber diameter is preferable in that it is easier to mix uniformly.

  When the additional fiber is mixed, the addition amount of the additional fiber in the total amount of the fine fiber and the additional fiber is not particularly limited, but is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30%. It is below mass%. Especially preferably, it is 20 mass% or less.

  Moreover, you may add a hydrophilic polymer in the case of preparation of a sheet | seat. Examples of hydrophilic polymers include polyethylene glycol, cellulose derivatives (hydroxyethyl cellulose, carboxyethyl cellulose, carboxymethyl cellulose, etc.), casein, dextrin, starch, modified starch, polyvinyl alcohol, modified polyvinyl alcohol (acetoacetylated polyvinyl alcohol, etc.), Polyethylene oxide, polyvinyl pyrrolidone, polyvinyl methyl ether, polyacrylic acid salts, polyacrylamide, acrylic acid alkyl ester copolymer, urethane copolymer and the like can be mentioned, but are not particularly limited.

  A hydrophilic low molecular weight compound can also be used in place of the hydrophilic polymer. Examples of hydrophilic low molecular weight compounds include, but are not limited to, glycerin, erythritol, xylitol, sorbitol, galactitol, mannitol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and butylene glycol.

  The mixing of the hydrophilic polymer or the hydrophilic low molecular compound is not particularly limited. For example, the hydrophilic polymer or the hydrophilic low molecular compound is added to the fine fiber-containing slurry before papermaking or coating. Can be done. The addition amount in the case of adding a hydrophilic polymer or a hydrophilic low molecular weight compound is preferably 1 to 200 parts by mass, more preferably 1 to 150 parts by mass, further preferably 100 parts by mass of the solid content of the fine fiber. Is 2 to 120 parts by mass, particularly preferably 3 to 100 parts by mass, but is not particularly limited.

3. Lamination of sheets, application, etc. The sheet of the present invention can be used as a single sheet, but at least one of an organic layer and an inorganic layer is formed on at least one surface and used as a laminate. You can also. By lamination, water resistance (water resistance, moisture resistance, water repellency) can be further imparted. When laminating the inorganic layer and the organic layer, the order is not particularly limited, but first laminating the organic layer on the surface of the base sheet smoothes the surface for forming the inorganic layer, and the formed inorganic layer Is preferable in that it can have fewer defects. In addition, other constituent layers other than the organic layer and the inorganic layer, for example, an easy adhesion layer for facilitating adhesion of the upper layer may be included. In the case of lamination, when used for applications in which transparency is particularly important, it is preferable not to include a heating step or a UV irradiation step that promotes yellowing of the sheet. It is preferable that the laminated body obtained by lamination includes at least one inorganic layer and at least one organic layer formed on at least one side of a base sheet layer made of a fine fiber-containing sheet. The number of layers such as an inorganic layer and an organic layer is not particularly limited. From the viewpoint of sufficient moisture resistance while maintaining flexibility and transparency, for example, it is preferable to laminate two to 15 layers of inorganic layers and organic layers alternately on one side, for example, 3 to 7 layers. More preferably, the layers are laminated.

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

  The resin used for the formation of the organic layer is not particularly limited, but epoxy resin, acrylic resin, oxetane resin, silsesquioxane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicon resin, A polyurethane resin, a silsesquioxane resin, a diallyl phthalate resin, or the like can be given. In order to obtain a low water-absorbing laminate, the resin preferably has a small number of hydrophilic functional groups such as hydroxy groups, carboxy groups, or amino groups.

  Since the sheet and laminate of the present invention have excellent transparency and strength, they are suitable for use as packaging materials for foods, cosmetics, pharmaceuticals, personal computers, home appliances and the like by taking advantage of characteristics such as light weight.

  In addition, the sheet and the laminate provided by the preferred embodiment are suitable for use as a display element, a lighting element, a solar cell or window material, or a panel or substrate for these, because yellowing is suppressed and optical properties are excellent. ing. More specifically, the sheet and the laminate are suitable for use as a flexible display, a touch panel, a liquid crystal display, a plasma display, an organic EL display, a field emission display, a rear projection television, and the like, and an LED element.

  Furthermore, the sheet and the laminate are suitable for use as a substrate for solar cells such as silicon solar cells and dye-sensitized solar cells. For use as a substrate, it may be laminated with a barrier film, ITO, TFT or the like. It is also suitable for use as a window material for automobiles, railway vehicles, aircraft, houses, office buildings, factories and the like. As a window material, you may laminate | stack films | membranes, such as a fluorine film and a hard-coat film | membrane, and an impact-resistant and light-resistant material as needed.

  Sheets and laminates can be used as structural materials other than those for transparent materials, taking advantage of properties such as low linear expansion coefficient, high elasticity, high strength, and light weight. Especially suitable for automobiles such as glazing, interior materials, skins, bumpers, railway vehicles, aircraft materials, personal computer casings, home appliance parts, packaging materials, building materials, civil engineering materials, marine products, and other industrial materials. Can be used.

  Sheets and laminates can be used for various products. Examples of products include computers, tablet terminals, mobile phones using the above display elements or displays; light bulbs, lighting (lighting fixtures / lighting devices), lighting, liquid crystal panel backlights, pockets using lighting elements Electric lights, bicycle headlights, car interior lights and meter lamps, traffic lights, high altitude lighting inside and outside buildings, home lighting, school lighting, medical lighting, factory lighting, plant growing lights, video lighting lighting Lighting in 24 hours or late-night stores such as convenience stores, lighting in refrigeration / freezers; houses, buildings, automobiles, rail cars, aircraft, home appliances using windows and structural materials, etc. be able to.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, the scope of the present invention is not limited by an Example.

<Example 1>
[Manufacture of phosphorylated pulp]
As softwood kraft pulp, it was used Oji Paper Co., Ltd. Pulp (Canadian Standard Freeness of solids 93 wt% basis weight 208g / m ² by sheet maceration is measured according to JIS P8121 (CSF) 700ml). 100 parts by mass of the above-mentioned softwood kraft pulp is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, and compressed to 49 parts by mass of ammonium dihydrogen phosphate and 130 parts by mass of urea. Pulp was obtained. The obtained chemical solution-impregnated pulp was dried with a dryer at 105 ° C. to evaporate the moisture and pre-dried. Then, it heated for 10 minutes with the ventilation dryer set to 140 degreeC, the group derived from phosphoric acid was introduce | transduced into the cellulose in a pulp, and the phosphorylated pulp was obtained.

[Cleaning of phosphorylated pulp]
The step of pouring 10000 parts by mass of ion-exchanged water with respect to 100 parts by mass as the absolute dry mass of the obtained phosphorylated pulp, stirring and dispersing uniformly, and then performing filtration and dehydration to obtain a dehydrated sheet twice Repeatedly, a dehydrated sheet A of phosphorylated pulp was obtained.

[Multiple phosphorylation]
Using the obtained phosphorylated pulp dehydrated sheet A as a raw material, the process of introducing phosphoric acid-derived groups and the process of filtration and dehydration were repeated twice more in the same manner as above (the total number of phosphorylation and filtration dehydration was 3 times) to obtain a dehydrated sheet B of phosphorylated pulp.

[Content of introduced substituents]
In the dehydrated sheet B of the phosphorylated pulp, the amount of phosphoric acid-derived groups introduced by the following titration method was 1.4 mmol / g.

[Measurement of Substituent Introduced Amount (Phosphate Derived Group Introduced Amount)]
The amount of substituent introduction is the amount of phosphoric acid-derived groups introduced into the fiber raw material. The larger the value, the more phosphoric acid-derived groups are introduced. The amount of substituent introduced was measured by diluting the target fine fibrous cellulose with ion-exchanged water so that the content was 0.2% by mass, and then treating with ion-exchange resin and titration with alkali. In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic ion exchange resin (Amberjet 1024; Organo Corporation, conditioned) is added to the 0.2 mass% cellulose fiber-containing slurry, and the mixture is shaken for 1 hour. It was. Thereafter, the mixture was poured onto a mesh having an opening of 90 μm to separate the resin and the slurry. In titration using an alkali, a change in the value of electrical conductivity indicated by the slurry was measured while adding a 0.1N sodium hydroxide aqueous solution to the cellulose fiber-containing slurry after ion exchange. That is, the alkali amount (mmol) required in the first region of the curve shown in FIG. 1 was divided by the solid content (g) in the titration target slurry to obtain the substituent introduction amount (mmol / g).

[Counterion conversion of phosphorylated pulp (H type)]
As an absolutely dry mass of the dehydrated sheet B of phosphorylated pulp, 5000 parts by mass of ion-exchanged water was added to 100 parts by mass for dilution. Next, 1N hydrochloric acid was added little by little while stirring to obtain a pulp slurry having a pH of 2 to 3. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, excess hydrochloric acid was sufficiently washed away by repeating the operation of filtration and dehydration to obtain a dehydrated sheet. By the above procedure, phosphorylated pulp (H type) was obtained in which the counter ion of the group derived from phosphoric acid was hydrogen (H) ion.

[Addition of organic counter ions to phosphorylated pulp]
As an absolutely dry mass of the phosphorylated pulp (H type), 5000 parts by mass of ion-exchanged water was added to 100 parts by mass to dilute. Next, a 10% by mass tetrabutylammonium hydroxide aqueous solution was added little by little with stirring to obtain a pulp slurry having a pH of 10 to 12. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated to sufficiently wash away the excess aqueous solution of tetrabutylammonium hydroxide. By the above procedure, phosphorylated pulp (TBA type) was obtained in which the counter ion of the group derived from phosphoric acid was tetrabutylammonium (TBA) ion.

[Machine processing]
Ion exchange water was added to the phosphorylated pulp (TBA type) to obtain a 1.0% by mass pulp suspension. This pulp suspension was passed five times at a pressure of 245 MPa with a wet atomizer (Sugino Machine Co., Ltd .: Ultimateizer) to obtain a fine fibrous cellulose suspension (TBA type).

[Sheet]
The concentration was adjusted so that the solid content concentration of the fine fibrous cellulose suspension (TBA type) was 0.5% by mass. The suspension was weighed so that the finished basis weight of the sheet was 75 g / m ² , developed on a commercially available acrylic plate, and dried in a constant temperature and humidity chamber of 35 ° C. and 15% RH. A damming metal frame (180 mm square) was disposed on the acrylic plate so as to have a predetermined basis weight. By the above procedure, a fine fibrous cellulose sheet was obtained.

<Example 2>
[Counterion conversion of phosphorylated pulp (Na type)]
In the counter ion conversion (TBA type) of the phosphorylated pulp of Example 1, a 1N NaOH aqueous solution was used instead of the 10 mass% tetrabutylammonium hydroxide aqueous solution, so that the counter ion of the group derived from phosphoric acid was sodium ( Phosphorylated pulp (Na type) became Na) ions.

[Machine processing]
Ion exchange water was added to the phosphorylated pulp (Na type) to make a 1.0 mass% pulp suspension. This pulp suspension was passed 5 times at a pressure of 245 MPa with a wet atomizer (Sugino Machine Co., Ltd .: Ultimateizer) to obtain a fine fibrous cellulose suspension (Na type).

[Counterion conversion of fine fibrous cellulose suspension (Na type) (H type)]
The fine fibrous cellulose suspension (Na type) was diluted to 0.5% by mass with ion-exchanged water, and 1/10 by volume of a strongly acidic ion-exchange resin (Amberjet 1024; Organo Corporation, conditioned) In addition, the mixture was stirred for 1 hour. Thereafter, the mixture was poured onto a mesh having an opening of 51 μm and filtered under reduced pressure to separate the resin and the slurry. By the above procedure, a fine fibrous cellulose suspension (H type) in which the counter ion of the group derived from phosphoric acid was hydrogen (H) ion was obtained.

[Addition of organic counter ions to fine fibrous cellulose suspension (H type)]
A 10% by mass aqueous solution of tetrabutylammonium hydroxide was weighed so that the content of phosphoric acid-derived groups (1.5 mmol / g) and tetrabutylammonium ions were equivalent, and the fine fibrous cellulose suspension (H Type). Thereafter, the mixture was stirred for 1 hour to obtain a fine fibrous cellulose suspension (TBA type) in which the counter ion of the phosphoric acid-derived group was tetrabutylammonium (TBA) ion. The subsequent procedure was the same as in Example 1 to obtain a fine fibrous cellulose sheet.

<Example 3>
The organic counter ion was applied to the fine fibrous cellulose suspension (H type) in Example 2 except that a 10% by mass tetraethylammonium hydroxide aqueous solution was used instead of the 10% tetrabutylammonium hydroxide aqueous solution. In the same manner as in Example 2, a fine fibrous cellulose sheet was obtained.

<Example 4>
In addition to the 10% tetrabutylammonium hydroxide aqueous solution, a 10% by mass tetrabutylphosphonium hydroxide aqueous solution was used in place of the 10% tetrabutylammonium hydroxide aqueous solution when applying organic counter ions to the fine fibrous cellulose suspension (H type) in Example 2. In the same manner as in Example 2, a fine fibrous cellulose sheet was obtained.

<Example 5>
When organic counter ions were applied to the fine fibrous cellulose suspension (H type) in Example 2, a 30% by mass lauryltrimethylammonium chloride aqueous solution (Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of the 10% tetrabutylammonium hydroxide aqueous solution. A fine fibrous cellulose sheet was obtained in the same manner as in Example 2 except that “Kachiogen TML”) was used.

<Reference Example 1>
In Example 1, mechanical treatment and sheet formation were performed without applying organic counter ions to the phosphorylated pulp. In addition, the remarkable crack generate | occur | produced in the case of sheeting, and the fine fibrous cellulose sheet was not obtained.

<Reference Example 2>
The fine fibrous cellulose suspension (Na type) obtained in Example 2 was not subjected to counter ion conversion (H type) or organic counter ion application, and had a molecular weight of 4.3 million to 4.8 million polyethylene oxide (Sumitomo Seika) 20 parts by mass of “PEO-18P”) was added to 100 parts by mass of the fine fibrous cellulose suspension (Na type). The subsequent procedure was the same as in Example 2 to obtain a fine fibrous cellulose sheet.

<Reference Example 3>
[Production of TEMPO oxidized pulp (TEMPO oxidation reaction)]
Undried Oji Paper Co., Ltd. softwood bleached kraft pulp equivalent to a dry mass of 100 parts by mass, TEMPO 1.25 parts by mass, and sodium bromide 12.5 parts by mass were dispersed in 10000 parts by mass of water. Subsequently, 13 mass% sodium hypochlorite aqueous solution was added so that the quantity of sodium hypochlorite might be 8.0 mmol with respect to 1.0 g of pulp, and reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 to 11, and the reaction was considered complete when no change in pH was observed.

[Cleaning of TEMPO oxidized pulp]
Thereafter, this pulp slurry is dehydrated to obtain a dehydrated sheet, and then the process of pouring 5000 parts by mass of ion exchange water, stirring and uniformly dispersing, and dehydrating by filtration to obtain a dehydrated sheet is repeated twice. It was. The amount of substituents (groups derived from carboxylic acid) introduced by the titration method was 1.5 mmol / g.

[Counterion exchange of TEMPO oxidized pulp]
Furthermore, 5000 mass parts of ion exchange water was added to the obtained dehydration sheet for dilution. Next, 1N hydrochloric acid was added little by little while stirring to obtain a pulp slurry having a pH of 2 to 3. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, excess hydrochloric acid was sufficiently washed away by repeating the operation of filtration and dehydration to obtain a dehydrated sheet. By the above procedure, TEMPO oxidized pulp (H type) was obtained in which the counter ion of the group derived from carboxylic acid was hydrogen (H) ion.

[Addition of organic counter ions to TEMPO oxidized pulp]
As the absolutely dry mass of the obtained TEMPO oxidized pulp (H type), 5000 parts by mass of ion-exchanged water was added to 100 parts by mass for dilution. Next, a 10% by mass tetrabutylammonium hydroxide aqueous solution was added little by little while stirring to obtain a pulp slurry having a pH of 10 to 12. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated to sufficiently wash away the excess aqueous solution of tetrabutylammonium hydroxide. By the above procedure, TEMPO oxidized pulp (TBA type) was obtained in which the counter ion of the carboxylic acid-derived group was tetrabutylammonium (TBA) ion.

  Subsequent procedures were the same as in Example 1 except that the TEMPO oxidized pulp (TBA type) was used instead of the phosphorylated pulp (TBA type) to obtain a fine fibrous cellulose sheet.

<Reference Example 4>
[Dephosphorylation (removal of phosphate-derived groups and counter ions)]
As a spacer, a heat-resistant rubber sheet (manufactured by Shin-Etsu Chemical Co., Ltd., X-30-4084-U) with a 150 mm square gap was placed as a spacer, and 50 mL of glycerin was developed in the hole. The fine fibrous cellulose sheet obtained in Example 4 was cut into 120 mm square, immersed in glycerin, and a stainless steel plate was stacked thereon and heated to 180 ° C. (manufactured by Imoto Seisakusho: manual hydraulic vacuum heating press) ). The fine fibrous cellulose sheet (TBA type) was treated at 180 ° C. for 30 minutes, and then immersed in 500 mL of water for cleaning. The washing was repeated three times, and the fine fibrous cellulose sheet was attached to a glass plate and dried by heating at 100 ° C. for 15 minutes. According to the above procedure, a fine fibrous cellulose sheet from which phosphoric acid-derived groups and counterions were removed was obtained.

<Reference Example 5>
In Reference Example 4, except for using the fine fibrous cellulose sheet obtained in Example 5, a fine fibrous cellulose sheet from which phosphoric acid-derived groups and counter ions were removed was the same procedure as in Reference Example 4. Obtained.

<Evaluation>
[Method]
The fine fibrous cellulose sheets produced in Examples 1 to 5 and Reference Examples 2 to 5 were evaluated according to the following evaluation methods. In Reference Example 1, since a fine fibrous cellulose sheet was not obtained, evaluation was not performed.

(1) Content of ionic substituent in fine fibrous cellulose sheet Phosphorus and sodium atom concentrations in the fine fibrous cellulose sheet were measured with a fluorescent X-ray analyzer (Spectras "PW2404"). That is, when the fine fibrous cellulose sheet is irradiated with X-rays, the inner shell electrons of phosphorus or sodium atoms are excited, and the phosphorus or sodium atoms released when the outer shell electrons transition to the vacancies. By measuring the intensity of characteristic X-rays, the concentration of phosphorus or sodium atoms was obtained. In Reference Example 3 containing a carboxylic acid-derived group as an ionic substituent, 5% was added to a sodium hydroxide aqueous solution in which the fine fibrous cellulose sheet was adjusted to pH 12 before analysis with a fluorescent X-ray analyzer. It was immersed for a minute, and the counter ion of the group derived from carboxylic acid was defined as sodium (Na) ion.

  In calculating the content of the phosphoric acid-derived group from the atomic concentration, calculation was performed from a calibration curve prepared by the following method. After preparing a fine fibrous cellulose sheet with a known content of phosphoric acid-derived groups and conducting fluorescent X-ray analysis, create a calibration curve for the characteristic X-ray intensity of phosphorus atoms and the content of phosphoric acid-derived groups did. Similarly, in the case of a group derived from a carboxylic acid, a fine fibrous cellulose sheet having a known content of the group derived from the carboxylic acid and having a Na salt type is prepared, and the characteristic X-ray intensity of the sodium atom and the group derived from the carboxylic acid A calibration curve for the content of was prepared.

In Example 4 and Reference Example 4, the content of phosphoric acid-derived groups in the fine fibrous cellulose sheet was determined by subtracting the phosphorus atom concentration derived from tetrabutylphosphonium hydroxide described later. About Example 1-5, all confirmed that content of group derived from carboxylic acid was less than 0.1 mmol / g.
In Table 1, the content of phosphoric acid-derived groups or carboxylic acid-derived groups with respect to the fine fibrous cellulose thus calculated is shown.

(2) Content of organic counter ion About Examples 1-3 and 5, and Reference Examples 1-3, 5, the trace nitrogen analyzer ("TN-110" manufactured by Mitsubishi Chemical Analytech Co., Ltd.) Nitrogen atom concentration was measured. That is, from the nitrogen atom concentration of the fine fibrous cellulose sheet obtained in Examples 1 to 6 and Reference Examples 2 to 6, using the nitrogen atom concentration of the fine fibrous cellulose sheet not provided with the organic counter ion as a reference value. By reducing the reference value, the concentration of nitrogen atoms derived from organic counter ions was used, and the organic counter ion content was calculated.

For Example 4 and Reference Example 4, the phosphorus atom concentration in the sheet was measured with a fluorescent X-ray analyzer (Spectras "PW2404"). That is, the intensity of the characteristic X-rays of phosphorus atoms emitted when electrons in the outer shell transition to vacancies generated by the excitation of inner electrons of phosphorus atoms when the sheet is irradiated with X-rays is measured. Thus, the concentration of phosphorus atoms was obtained. A filter paper having a known phosphorus introduction amount was prepared and subjected to fluorescent X-ray analysis in the same manner as the fine fibrous cellulose sheet, and then a calibration curve for the characteristic X-ray intensity of phosphorus atoms and the phosphorus introduction amount was prepared. By subtracting the phosphorus atom concentration of the fine fibrous cellulose sheet that has not been given the organic counter ion as the reference value from the phosphorus atom concentration calculated from the calibration curve, the phosphorus atom concentration derived from the organic counter ion is obtained as the organic counter ion. The content was calculated.
In Table 1, the content of organic counter ions with respect to the sheet thus calculated is shown.

(3) Density A fine fibrous cellulose sheet cut to 100 mm square was conditioned at 23 ° C. and a relative humidity of 50% for 24 hours, and then the weight was measured to calculate the US basis weight (g / m ² ). Furthermore, the density of the fine fibrous cellulose sheet was calculated by dividing by the thickness of the fine fibrous cellulose sheet.

(4) Wrinkles / Cracks When forming a sheet of fine fibrous cellulose suspension, in accordance with the size of each 180 mm damming metal frame, a square of 2 cm square is arranged on the back of the acrylic plate in a total of 9 × 9 in the vertical direction. The mass was described. The fine fibrous cellulose sheet was observed from above with the acrylic plate attached to the acrylic plate, and the masses where wrinkles and cracks were generated in the fine fibrous cellulose sheet were counted. The mass where wrinkles and cracks occurred was evaluated as ○ when the mass was less than 20% of the total mass, and x when the mass was 20% or more.

(5) Total light transmittance Based on JIS standard K7361, the total light transmittance was measured using the haze meter ("HM-150" by Murakami Color Research Laboratory Co., Ltd.).

(6) Haze Based on JIS standard K7136, the haze was measured using a haze meter ("HM-150" manufactured by Murakami Color Research Laboratory Co., Ltd.).

(7) Tensile properties In accordance with JIS standard K7127, using a tensile tester (“Tensilon” manufactured by A & D), the tensile tester (A Tensile strength, tensile modulus, and tensile elongation were measured using “Tensilon” manufactured by And Day Co., Ltd.

(8) Yellowness before and after heating Based on JIS standard K7373, yellowness (YI) before and after sheet heating was measured using a colorimeter (“Color Cute i” manufactured by Suga Test Instruments Co., Ltd.). Further, the difference in YI before and after heating was evaluated as ΔYI. The heating conditions were vacuum drying at 200 ° C. for 4 hours.

(9) Pencil hardness Pencil hardness was measured according to JIS standard K5600 except that the load applied to the sample was 500 g.

(10) Molding followability A fine fibrous cellulose sheet was cut into a 150 mm square and packaged so as to wrap the whole of a wooden cylindrical molded body having a diameter of 50 mm and a height of 60 mm. Next, the cylindrical molded body was visually observed from above and evaluated according to the following criteria.

○: No voids are observed between the cylindrical molded body and the fine fibrous cellulose sheet, and no cracks are observed in the fine fibrous cellulose sheet.
(Triangle | delta): Although there exists a space | gap between a cylindrical molded object and a fine fibrous cellulose sheet, a crack is not looked at by a fine fibrous cellulose sheet.
X: A space | gap exists between a cylindrical molded object and a fine fibrous cellulose sheet, and a crack is seen in a fine fibrous cellulose sheet.
In addition, among the objects evaluated as “good” according to the above criteria, those in which almost no wrinkles were found on the packaged sheet were evaluated as “good”.

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

  As is clear from Table 1, in Examples 1 to 5 where organic counter ions were applied, Reference Example 2 where organic counter ions were not applied, Reference Examples 4 and 5 where organic counter ions were removed, and In comparison, a flexible sheet having a low tensile modulus and pencil hardness was obtained. Moreover, the molding followability was also good, suggesting that the utility as a packaging material is high. On the other hand, in Reference Example 3, the flexibility and molding followability were good, but the ΔYI value by heating was large, suggesting that there was a practical problem.

<Example 6 (Manufacturing Example 1 of laminate)>
Using the sheet obtained in any of Examples 1 to 5, a laminate is obtained by the following procedure.
An aluminum oxide film is formed on the sheet with SUNALE R-100B (Picosun). As an aluminum raw material, trimethylaluminum (TMA) and H ₂ O are used for the oxidation of TMA. The chamber temperature is set to 150 ° C., the TMA pulse time is 0.1 seconds, the purge time is 4 seconds, the H ₂ O pulse time is 0.1 seconds, and the purge time is 4 seconds. By repeating this cycle for 405 cycles, a laminate in which an aluminum oxide film having a thickness of 30 nm is laminated on both sides of the sheet is obtained.

<Example 7 (Manufacture example 2 of a laminated body)>
Using the sheet obtained in any of Examples 1 to 5, a laminate is obtained by the following procedure.
Silsesquioxane resin (Arakawa Chemical Industries "Composeran SQ107") 10 parts by weight, curing agent (Arakawa Chemical Industries "HBSQ202") 30 parts by weight, isopropyl alcohol 60 parts by weight are mixed, coating liquid obtain. Next, the coating solution is applied to one side of the substrate with a Mayer bar. Thereafter, after drying at 100 ° C. for 3 minutes, UV coating of 300 mJ / cm ² was irradiated using a UV conveyor device (“ECS-4011GX” manufactured by Eye Graphics) to cure the coating solution, and the thickness was 5 μm. The resin layer is formed. Furthermore, a resin layer having a thickness of 5 μm is formed on the opposite surface in the same procedure.

<Example 8 (Production Example 3 of Laminate)>
Using the sheet obtained in any of Examples 1 to 5 or the sheet obtained in Example 6, a laminate is obtained by the following procedure.
50 parts by weight of a urethane acrylate resin composition (“Beamset 575CB” manufactured by Arakawa Chemical Industries) and 50 parts by weight of methyl ethyl ketone are mixed to obtain a curable resin precursor solution. The curable resin precursor solution is applied onto the sheet using a Mayer bar. Next, after drying at 80 ° C. for 3 minutes, UV light of 300 mJ / cm ² was irradiated using a UV conveyor device (“ECS-4011GX” manufactured by Eye Graphics Co., Ltd.) to cure the curable resin precursor solution. A resin layer having a thickness of 5 μm is formed. Further, by forming a resin layer having a thickness of 5 μm on the opposite surface in the same procedure, a sheet in which the resin layer is laminated on both surfaces on which the aluminum oxide film is laminated is obtained.

<Example 9 (Production Example 4 of Laminate)>
Using the sheet obtained in any of Examples 1 to 5 or the sheet obtained in Example 7, a laminate is obtained by the following procedure.
A silicon oxynitride film is formed on the sheet using an ICP-CVD roll-to-roll apparatus (Celback). A resin laminated sheet is bonded to the upper surface of a carrier film (PET film) with a double-sided tape and placed in a vacuum chamber. The temperature in the vacuum chamber was set to 50 ° C., and the inflow gas was silane, ammonia, oxygen, and nitrogen. Plasma discharge is generated and film formation is performed for 45 minutes to obtain a sheet in which a silicon oxynitride film having a thickness of 500 nm is laminated on one surface of a resin laminated sheet. Furthermore, a sheet having a 500 nm-thick silicon oxynitride film laminated on both surfaces of the sheet is obtained by performing film formation on the opposite surface in the same procedure.

Claims (7)

Fine fibers having an ionic substituent;
An organic onium ion which is a counter ion of the ionic substituent;
Including
A sheet having an organic onium ion content of 0.10 mmol / g or more,
The content of a substituent derived from a phosphate group and a phosphate group is 0.1 mmol / g or more with respect to the fine fiber, and the fine fiber does not contain a carboxy group and a substituent derived from the carboxy group. Or the content of the substituent derived from the said carboxy group and a carboxy group is less than 0.1 mmol / g with respect to the said fine fiber. The sheet according to claim 1, wherein the organic onium ion has 4 or more carbon atoms. The sheet according to claim 1 or 2, wherein the density is 1.0 g / cm ³ or more. The sheet according to any one of claims 1 to 3, wherein the tensile elastic modulus at a temperature of 23 ° C and a relative humidity of 50% is 3.5 GPa or less. Pencil hardness is F or less, The sheet | seat as described in any one of Claims 1-4. The sheet | seat as described in any one of Claims 1-5 whose yellowing degree change ((DELTA) YI) is 70 or less. A sheet according to any one of claims 1 to 6;
A laminate comprising at least one of an inorganic layer and an organic layer formed on at least one side of the sheet.

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