JP7139767B2 - sanitary tissue paper - Google Patents

Description

The present invention relates to sanitary thin paper (toilet paper, tissue paper, etc.).

Conventionally, sanitary thin papers such as tissue paper, toilet paper, tissue paper, etc. have been widely used. Such sanitary thin paper is distributed in a state in which a plurality of sheets of sanitary thin paper are folded and stacked to form a bundle, or in a state in which a series of sanitary thin paper is rolled.

In recent years, various functions have been added to toilet paper and tissue paper to increase their added value. For example, Patent Literature 1 discloses sanitary thin paper containing metal-supported cellulose fibers in which predetermined metal particles are supported on oxidized cellulose fibers having carboxyl groups or carboxylate groups on their surfaces. Further, Patent Document 2 discloses a toilet paper to which a deodorant containing an organic acid is applied. Furthermore, Patent Document 3 discloses a tissue paper having a functional layer containing a deodorant component (such as polyphenol).

JP 2015-045113 A JP 2014-198093 A JP 2014-198186 A

As described above, sanitary thin papers with deodorant functions have been developed. However, conventional sanitary thin papers to which a deodorant has been applied have the problem that the deodorant sometimes falls off unintentionally during use, and the deodorizing effect does not last. Moreover, when ions of metal elements are used as a deodorant, it is difficult to secure a sufficient amount of ions to be supported, and a sufficient deodorizing effect may not be exhibited.

In order to solve the problems of the prior art, the inventors of the present invention conducted studies with the aim of providing a sanitary thin paper capable of exhibiting an excellent deodorizing function.

As a result of intensive studies to solve the above problems, the present inventors found that the sanitary thin paper can exhibit excellent deodorizing function by incorporating fibrous cellulose having a fiber width of 1000 nm or less into the sanitary thin paper. is obtained.
Specifically, the present invention has the following configurations.

[1] Sanitary thin paper containing fibrous cellulose with a fiber width of 1000 nm or less.
[2] The sanitary thin paper according to [1], wherein the fibrous cellulose has an anionic group.
[3] The sanitary thin paper according to [2], wherein the anionic group is at least one selected from a carboxyl group, a substituent derived from a carboxyl group, a phosphate group, and a substituent derived from a phosphate group.
[4] The sanitary thin paper according to [2] or [3], wherein the anionic group is at least one selected from a phosphate group and a substituent derived from a phosphate group.
[5] The sanitary thin paper according to any one of [1] to [4], wherein the fibrous cellulose carries at least one metal component selected from Ag, Au, Pt, Pd, Cu and Zn.
[6] The sanitary thin paper according to any one of [1] to [5], wherein the content of fibrous cellulose is 0.05 to 15 g/m ² .
[7] Toilet paper made of the sanitary thin paper according to any one of [1] to [6].
[8] A tissue paper made of the sanitary thin paper according to any one of [1] to [6].

ADVANTAGE OF THE INVENTION According to this invention, the sanitary thin paper which can exhibit the outstanding deodorant function can be obtained.

FIG. 1 is a graph showing the relationship between the amount of dropped NaOH and electrical conductivity with respect to fiber raw materials having phosphate groups. FIG. 2 is a graph showing the relationship between the amount of dropped NaOH and electrical conductivity with respect to fiber raw materials having carboxyl groups.

The present invention will be described in detail below. Although the constituent elements described below may be described based on representative embodiments and specific examples, the present invention is not limited to such embodiments.

(sanitary thin paper)
TECHNICAL FIELD The present invention relates to sanitary thin paper containing fibrous cellulose with a fiber width of 1000 nm or less. The sanitary thin paper may be thin paper cut into a predetermined size, or may be thin paper wound into a roll. When the sanitary thin paper is thin paper cut into a predetermined size, it is preferable that a plurality of sanitary thin paper sheets be folded and stacked and stored in an outer container (such as a storage box). Further, the thin paper that exists in a rolled state is wound around a core paper tube, for example, to form a sheet roll. In this specification, fibrous cellulose having a fiber width of 1000 nm or less is also referred to as fine fibrous cellulose.

Since the sanitary thin paper of the present invention has the above structure, it exhibits an excellent deodorant function. Specifically, since the sanitary thin paper contains fibrous cellulose with a fiber width of 1000 nm or less, it is possible to capture a functional substance that exerts a deodorizing function between the fibers or to carry it on the fibers. . As a result, detachment or the like of the functional substance that exerts the deodorizing function is suppressed, and the sanitary thin paper can exert an excellent deodorizing function over a long period of time.

Examples of functional substances that exert a deodorizing function include at least one metal component selected from Ag, Au, Pt, Pd, Cu and Zn. Such metal components include Ag, At least one selected from Cu and Zn is preferable, and Ag is particularly preferable. Note that fibrous cellulose itself having a fiber width of 1000 nm or less also exhibits a deodorizing effect.

Since the sanitary thin paper of the present invention has the above structure, it can carry other functional substances in addition to the functional substance that exerts the deodorizing function. Other functional substances may further include aromatic substances, antibacterial substances, substances having a virus-inactivating action, substances having a moisturizing action, and the like. By containing such a functional substance, various functions can be imparted to the sanitary thin paper in addition to the deodorizing function.

Moreover, since the sanitary thin paper of the present invention has the above structure, the strength of the sanitary thin paper is enhanced. By containing fine fibrous cellulose, the tensile strength of the sanitary thin paper can be increased, and the tensile strength of the wet sanitary thin paper can also be increased.

The sanitary thin paper may be a sheet made of fibrous cellulose with a fiber width of 1000 nm or less, but is preferably a layer containing other fibers. Other fibers can include at least one selected from natural fibers, synthetic fibers and regenerated fibers. Natural fibers include pulp, cotton, wool, silk, and the like. Synthetic fibers include polyester fibers, polyolefin fibers, nylon fibers, acrylic resin fibers, and the like. Examples of regenerated fibers include rayon fibers and acetate fibers. Among them, the sanitary thin paper preferably contains pulp, and preferably contains coarse pulp fibers having a fiber width exceeding 1000 nm.

The content of fine fibrous cellulose in the sanitary thin paper is preferably 0.05 g/m ² or more, more preferably 0.1 g/m ² or more, and more preferably 0.5 g/m ² or more. More preferred. The content of fine fibrous cellulose is preferably 15 g/m ² or less, more preferably 12 g/m ² or less, and even more preferably 10 g/m ² or less.

When the sanitary thin paper contains pulp fibers, the ratio of pulp fibers to fine fibrous cellulose is preferably 1:0.0001 to 1:0.1, and 1:0.0005 to 1:0.05. is more preferable.

The sheet forming the sanitary thin paper may contain other components in addition to the fibrous cellulose having a fiber width of 1000 nm or less and the other fibers described above. Other components include, for example, a binder component. Examples of binder components include thermoplastic resins and starch. Examples of binder components include water-soluble polymers, and specific examples include carboxyvinyl polymer, polyvinyl alcohol, alkyl methacrylate/acrylic acid copolymer, polyvinylpyrrolidone, sodium polyacrylate, polyethylene glycol, diethylene glycol, Examples include triethylene glycol, polyethylene oxide, propylene glycol, dipropylene glycol, polypropylene glycol, isoprene glycol, hexylene glycol, 1,3-butylene glycol, polyacrylamide, and the like.

Other components include dry paper strength agents, wet paper strength agents, softeners, fragrances, and the like. Examples of dry paper strength agents include cationized starch, polyacrylamide (PAM), carboxymethylcellulose (CMC) and the like. Examples of wet paper strength agents include polyamide epichlorohydrin, urea, melamine, and thermally crosslinkable polyacrylamide. Examples of softening agents include anionic surfactants, nonionic surfactants, and cationic surfactants. Fragrances include plant essential oils (lavender, rosemary, peppermint, spearmint, eucalyptus, etc.), menthol, citronellol, and the like. The above optional components may be used singly or in combination of two or more.

The sanitary thin paper may be a one-ply sanitary thin paper, or may be a two-ply or more sanitary thin paper. Here, the number of plies of sanitary thin paper means the number of superimposed sanitary thin paper webs. When the sanitary thin paper has two or more plies, the fine fibrous cellulose may be contained in either layer, but is preferably contained on the exposed surface of the sanitary thin paper. This makes it easier for the deodorizing function to be exhibited.

The basis weight per ply of the sanitary thin paper is preferably 5 to 30 g/m ² , more preferably 5 to 25 g/m ² , even more preferably 10 to 25 g/m ² . By setting the basis weight per ply of the sanitary thin paper within the above range, the deodorizing function can be exhibited more effectively.

The thickness of one ply of sanitary thin paper is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and particularly preferably 40 μm or more. The thickness of one ply of the sanitary thin paper is preferably 200 μm or less, more preferably 170 μm or less, even more preferably 150 μm or less.

Sanitary thin paper is used as, for example, toilet paper, tissue paper, hand paper, and the like. In this case, the sanitary thin paper may be embossed depending on the use of the sanitary thin paper. In this case, the embossing may be applied uniformly over the entire area of the sanitary thin paper, but may be applied unevenly in order to impart design and functionality. Different densities are possible. The embossed pattern (shape) is not particularly limited, and may be circular, elliptical, or polygonal (triangle, quadrangle, pentagon, hexagon, etc.).

When sanitary thin paper is embossed, the diameter of one emboss (the diameter of the circumscribed circle in the case of a polygon, the longest diameter in the case of an ellipse) is preferably 0.5 mm or more and 2 mm or less. , 0.7 mm or more and 1.3 mm or less. The emboss density is preferably 5/cm ² or more and 50/cm ² or less, more preferably 10/cm ² or more and 30/cm ² or less, and 15/cm ² or more and 25/cm 2 or more. cm ² or less is more preferable. The height of the emboss is preferably 30-1000 μm, more preferably 50-500 μm, even more preferably 50-300 μm, particularly preferably 100-250 μm.

The embossing as described above is preferably formed, for example, by embossing the entire area of the two plies of sanitary thin paper in a state of being superimposed. This makes it easier for the two-ply sanitary thin paper to be integrated by embossing.

(Toilet Paper)
The present invention also relates to toilet paper made of the sanitary thin paper described above. In this case, it is preferable that the toilet paper is wound around a core paper tube and used as a toilet roll.

The inner diameter of the core paper tube used for the toilet roll is preferably 50 mm or less, more preferably 45 mm or less. The inner diameter of the core paper tube is preferably 10 mm or more, more preferably 20 mm or more.
The diameter of the toilet roll is preferably 100 mm or more, more preferably 105 mm or more, and even more preferably 110 mm or more. Also, the diameter of the toilet roll is preferably 300 mm or less.
The core paper tube may also contain fine fibrous cellulose.

(tissue paper)
The present invention also relates to a tissue paper made of the sanitary thin paper described above. In this case, it is preferable that a tissue paper bundle formed by folding and stacking a plurality of tissue papers is housed in an exterior container (storage box, packaging bag, etc.) to form a tissue paper product. In the tissue paper product, the tissue paper is pulled out one by one from the housed tissue paper bundle and used.

The outer container for accommodating the tissue paper bundle may be a paper material containing pulp as a main raw material, or may be a resin container or a resin bag. In addition, fine fibrous cellulose can be contained in such an outer container.

(fine fibrous cellulose)
Sanitary thin paper contains fibrous cellulose (fine fibrous cellulose) with a fiber width of 1000 nm or less.

The average fiber width of the fibrous cellulose is preferably 2 nm or more and 1000 nm or less, more preferably 2 nm or more and 100 nm or less, even more preferably 2 nm or more and 50 nm or less, and particularly 2 nm or more and 10 nm or less. preferable. By setting the average fiber width of the fibrous cellulose to 2 nm or more, the dissolution of cellulose molecules in water is suppressed, and the effect of improving the strength, rigidity, and dimensional stability of the fibrous cellulose can be more readily exhibited. can. The fibrous cellulose is, for example, single fibrous cellulose.

The average fiber width of fibrous cellulose is measured, for example, using an electron microscope as follows. First, an aqueous suspension of fibrous cellulose with 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-coated grid to form a sample for TEM observation. and SEM images of surfaces cast on glass may be observed if they contain wide fibers. Then, an electron microscope image is observed at a magnification of 1,000, 5,000, 10,000, or 50,000 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) A single straight line X is drawn at an arbitrary point in the observed image, and 20 or more fibers intersect the straight line X.
(2) Draw a straight line Y that intersects the straight line perpendicularly in the same image, and 20 or more fibers intersect the straight line Y.
Widths of fibers intersecting the straight lines X and Y are visually read from the observation image satisfying the above conditions. In this way, at least three sets of observed images of surface portions that do not overlap each other are obtained. Then, for each image, the width of the fiber that crosses straight line X and straight line Y is read. This gives at least 20 x 2 x 3 = 120 fiber width readings. Then, the average value of the read fiber widths is taken as the average fiber width of the fibrous cellulose.

Although the fiber length of the fibrous cellulose is not particularly limited, it 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, destruction of the crystalline regions of the fibrous cellulose can be suppressed. Moreover, it becomes possible to make the slurry viscosity of fibrous cellulose into an appropriate range. The fiber length of fibrous cellulose can be determined by image analysis using, for example, TEM, SEM, and AFM.

Preferably, the fibrous cellulose has a Type I crystal structure. Here, the fact that the fibrous cellulose has a type I crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ=1.5418 Å) 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 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, even more preferably 50% or more. As a result, even better performance can be expected in terms of heat resistance and low coefficient of linear thermal expansion. The degree of crystallinity is determined by a conventional method from the pattern of X-ray diffraction profiles (Seagal et al., Textile Research Journal, vol. 29, p. 786, 1959).

Although the axial ratio (fiber length/fiber width) of fibrous cellulose is not particularly limited, it is preferably 20 or more and 10,000 or less, and more preferably 50 or more and 1,000 or less. A sheet containing fine fibrous cellulose can be easily formed by making the axial ratio equal to or higher than the above lower limit. By setting the axial ratio to the above upper limit or less, handling such as dilution becomes easier, for example, when fibrous cellulose is treated as an aqueous dispersion, which is preferable.

The fibrous cellulose in this 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 having a high axial ratio is realized by the method for producing fine fibrous cellulose described later.

The fibrous cellulose in this embodiment preferably has an anionic group. Examples of anionic groups include, for example, a phosphate group or a substituent derived from a phosphate group (sometimes simply referred to as a phosphate group), a carboxyl group or a substituent derived from a carboxyl group (sometimes simply referred to as a carboxyl group), and It is preferably at least one selected from a sulfone group or a substituent derived from a sulfone group (sometimes referred to simply as a sulfone group), a carboxyl group, a substituent derived from a carboxyl group, a phosphate group, and a phosphate group It is more preferably at least one selected from substituents derived from and particularly preferably at least one selected from a phosphate group and a substituent derived from a phosphate group. Phosphate groups have more anionic groups per molecule than carboxyl groups and the like, so they can carry more metal components. It is believed that this is the reason why a more excellent deodorizing effect is exhibited.

A phosphate group is a divalent functional group, for example, phosphoric acid with the hydroxyl group removed. Specifically, it is a group represented by —PO ₃ H ₂ . Substituents derived from a phosphate group include substituents such as salts of phosphate groups and phosphate ester groups. A substituent derived from a phosphoric acid group may be contained in the fibrous cellulose as a condensed group (for example, a pyrophosphate group) of the phosphoric acid group.
A phosphoric acid group or a substituent derived from a phosphoric acid group is, for example, a substituent represented by the following formula (1).

In formula (1), a, b and n are natural numbers (where a=b×m). a of α ^{1 , α 2} , . All of αn and α' may be O 2 ⁻ . Each 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 A hydrogen group, an unsaturated-cyclic hydrocarbon group, an aromatic group, or a derivative group thereof.

Examples of the saturated straight-chain hydrocarbon group include, but are not limited to, methyl group, ethyl group, n-propyl group, n-butyl group, and the like. The saturated-branched hydrocarbon group includes i-propyl group, t-butyl group and the like, but is not particularly limited. The saturated cyclic hydrocarbon group includes, but is not particularly limited to, a cyclopentyl group, a cyclohexyl group, and the like. The unsaturated straight-chain hydrocarbon group includes, but is not particularly limited to, a vinyl group, an allyl group, and the like. The unsaturated-branched hydrocarbon group includes i-propenyl group, 3-butenyl group and the like, but is not particularly limited. The unsaturated-cyclic hydrocarbon group includes, but is not limited to, a cyclopentenyl group, a cyclohexenyl group, and the like. The aromatic group includes, but is not particularly limited to, a phenyl group, a naphthyl group, or the like.

In addition, as the derivative group for R, at least one functional group such as a carboxyl group, a hydroxyl group, or an amino group is added or substituted with respect to the main chain or side chain of the various hydrocarbon groups described above. Examples include, but are not limited to, groups. Although the number of carbon atoms constituting the main chain of R is not particularly limited, it is preferably 20 or less, more preferably 10 or less. By setting the number of carbon atoms constituting the main chain of R within the above range, the molecular weight of the phosphate group can be set within an appropriate range, facilitating penetration into the fiber raw material and increasing the yield of fine cellulose fibers. can also

β ^b+ is a monovalent or higher cation composed of an organic substance or an inorganic substance. Examples of monovalent or higher-valent cations composed of organic substances include aliphatic ammonium and aromatic ammonium. Examples include cations of divalent metals such as calcium and magnesium, hydrogen ions, and the like, but are not particularly limited. These may be applied singly or in combination of two or more. As the cation having a valence of 1 or more composed of an organic substance or an inorganic substance, sodium or potassium ions are preferable, but not particularly limited, because they are less likely to turn yellow when fiber raw materials containing β are heated and are easily industrially available.

The amount of anionic groups introduced into fibrous cellulose is, for example, preferably 0.10 mmol/g or more, more preferably 0.20 mmol/g or more, more preferably 0.50 mmol/g per 1 g (mass) of fibrous cellulose. It is more preferably 1.00 mmol/g or more, and particularly preferably 1.00 mmol/g or more. The amount of anionic groups introduced into fibrous cellulose is, for example, preferably 3.65 mmol/g or less, more preferably 3.50 mmol/g or less, more preferably 3.00 mmol/g per 1 g (mass) of fibrous cellulose. /g or less is more preferable. By setting the amount of the anionic group to be introduced within the above range, the fiber raw material can be easily made finer, and the stability of the fibrous cellulose can be enhanced.
Here, the unit mmol/g indicates the amount of substituents per 1 g mass of fibrous cellulose when the counter ion of the anion group is hydrogen ion (H ⁺ ).

The amount of anionic groups introduced into fibrous cellulose can be measured, for example, by conductivity titration. In the measurement by the conductivity titration method, the introduced amount is measured by determining the change in conductivity while adding an alkali such as an aqueous sodium hydroxide solution to the obtained slurry containing the fibrous cellulose.

FIG. 1 is a graph showing the relationship between the amount of NaOH added to fibrous cellulose having a phosphate group and electrical conductivity. The amount of phosphate groups 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. In addition, before the treatment with the strongly acidic ion exchange resin, a defibration treatment similar to the fibrillation treatment step described below may be performed on the object to be measured, if necessary. Next, change in electrical conductivity is observed while adding an aqueous sodium hydroxide solution to obtain a titration curve as shown in FIG. As shown in FIG. 1, the electrical conductivity drops sharply at first (hereinafter referred to as "first region"). After that, the conductivity starts to rise slightly (hereinafter referred to as "second region"). After that, the increment of conductivity increases (hereinafter referred to as "third region"). The boundary point between the second region and the third region is defined as the point where the second derivative of the conductivity, that is, the amount of change in the increment (slope) of the conductivity is maximized. Thus, three regions appear in the titration curve. Of these, the amount of alkali required in the first region is equal to the amount of strong acid groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weak acid groups in the slurry used for titration. be equal. When the phosphate groups condense, the weakly acidic groups are apparently lost, and the amount of alkali required for the second region becomes smaller than the amount of alkali required for the first region. On the other hand, the amount of strongly acidic groups coincides with the amount of phosphorus atoms regardless of the presence or absence of condensation. Therefore, the amount of phosphate groups introduced (or the amount of phosphate groups) or the amount of substituents introduced (or the amount of substituents) means the amount of strongly acidic groups. Therefore, the value obtained by dividing the alkali amount (mmol) required in the first region of the titration curve obtained above by the solid content (g) in the slurry to be titrated is the amount of phosphate group introduced (mmol/ g).

FIG. 2 is a graph showing the relationship between the amount of NaOH added to fibrous cellulose having carboxyl groups and electrical conductivity. The amount of carboxyl groups 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. In addition, before the treatment with the strongly acidic ion exchange resin, a defibration treatment similar to the fibrillation treatment step described below may be performed on the object to be measured, if necessary. Next, change in electrical conductivity is observed while adding an aqueous sodium hydroxide solution to obtain a titration curve as shown in FIG. As shown in FIG. 2, the titration curve has a first region where the increment (slope) of the conductivity becomes almost constant after the electrical conductivity decreases, and then the increment (slope) of the conductivity increases. It is divided into a second area. The boundary point between the first region and the second region is defined as the point where the second differential value of the conductivity, that is, the amount of change in the increment (slope) of the conductivity becomes maximum. Then, the value obtained by dividing the alkali amount (mmol) required in the first region of the titration curve by the solid content (g) in the fine fibrous cellulose-containing slurry to be titrated is the amount of carboxyl groups introduced ( mmol/g).

The amount of carboxyl groups introduced above (mmol/g) is the amount of substituent groups per 1 g of mass of fibrous cellulose when the counter ion of the carboxyl groups is hydrogen ion (H ⁺ ) (hereinafter referred to as the amount of carboxyl groups (acid type)). On the other hand, when the counterion of the carboxyl group is substituted with an arbitrary cation C so as to have a charge equivalent, the denominator is converted to the mass of fibrous cellulose when the cation C is the counterion. , the amount of carboxyl groups (hereinafter referred to as the amount of carboxyl groups (C-type)) possessed by fibrous cellulose whose counterion is cation C can be obtained.
That is, the amount of carboxyl group introduced is calculated by the following formula.
Amount of carboxyl groups introduced (type C) = amount of carboxyl groups (acid form) / {1 + (W-1) x (amount of carboxyl groups (acid form)) / 1000}
W: Formula weight per valence of cation C (for example, 23 for Na and 9 for Al)

<Manufacturing process of fine fibrous cellulose>
Microfibrous cellulose is produced from fibrous raw materials containing cellulose. The fibrous raw material containing cellulose is not particularly limited, but pulp is preferably used because it is readily available and inexpensive. Pulp includes, for example, wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include, but are not limited to, 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 chemigroundwood pulp (CGP), groundwood pulp (GP) and thermomechanical pulp (TMP, BCTMP) A mechanical pulp etc. are mentioned. Non-wood pulps include, but are not limited to, cotton-based pulps such as cotton linters and cotton lints, and non-wood-based pulps such as hemp, straw, and bagasse. Examples of deinked pulp include, but are not limited to, deinked pulp made from waste paper. The pulp of this embodiment may be used alone or in combination of two or more.
Among the above pulps, wood pulp and deinked pulp are preferred, for example, from the viewpoint of availability. In addition, among wood pulps, the cellulose ratio is high and the yield of fine fibrous cellulose at the time of defibration is high, and the decomposition of cellulose in the pulp is small, and fine fibrous cellulose of long fibers with a large axial ratio can be obtained. From the point of view, for example, chemical pulp is more preferable, and kraft pulp and sulfite pulp are more preferable.

As the fiber raw material containing cellulose, for example, cellulose contained in sea squirts and bacterial cellulose produced by acetic acid bacteria can be used. Fibers formed by straight-chain nitrogen-containing polysaccharide polymers such as chitin and chitosan can also be used instead of fiber raw materials containing cellulose.

<Phosphate group introduction step>
When the fine fibrous cellulose has a phosphate group, the process for producing the fine fibrous cellulose includes a phosphate group introduction step. In the step of introducing a phosphate group, at least one compound selected from compounds capable of introducing a phosphate group (hereinafter also referred to as "compound A") is added to cellulose by reacting with a hydroxyl group possessed by a fiber raw material containing cellulose. It is a step of acting on a fiber raw material containing. Through this step, a phosphate group-introduced fiber is obtained.

In the phosphate group-introducing step according to the present embodiment, the reaction between the fiber material containing cellulose and compound A is performed in the presence of at least one selected from urea and derivatives thereof (hereinafter also referred to as "compound B"). may On the other hand, the reaction between the cellulose-containing fiber raw material and the compound A may be carried out in the absence of the compound B.

An example of the method of allowing the compound A to act on the fiber raw material in the presence of the compound B includes 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. Among these, it is preferable to use a fiber raw material in a dry state or a wet state, and it is particularly preferable to use a fiber raw material in a dry state, because the uniformity of the reaction is high. Although the form of the fiber material is not particularly limited, it is preferably in the form of cotton or a thin sheet, for example. The compound A and the compound B can be added to the fiber raw material in the form of a powder, a solution dissolved in a solvent, or a melted state by heating to a melting point or higher. Among these, it is preferable to add in the form of a solution dissolved in a solvent, particularly in the form of an aqueous solution, since the uniformity of the reaction is high. Moreover, the compound A and the compound B may be added simultaneously to the fiber raw material, may be added separately, or may be added 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 solution, the fiber raw material may be immersed in the solution to absorb the liquid and then taken out, or the fiber raw material may be taken out. The solution may be added dropwise to the Further, the necessary amount of compound A and compound B may be added to the fiber raw material, or after adding excessive amounts of compound A and compound B to the fiber raw material, the excess compound A and compound B are removed by pressing or filtering. may be removed.

Examples of the compound A used in this embodiment include phosphoric acid or its salts, dehydrated condensed phosphoric acid or its salts, phosphoric anhydride (phosphorus pentoxide) and the like, but are not particularly limited. Phosphoric acid of various purities can be used, for example, 100% phosphoric acid (orthophosphoric acid) or 85% phosphoric acid can be used. Dehydration-condensed phosphoric acid is obtained by condensing two or more molecules of phosphoric acid by dehydration reaction, and examples thereof include pyrophosphoric acid and polyphosphoric acid. Phosphates and dehydrated condensed phosphates include lithium salts, sodium salts, potassium salts and ammonium salts of phosphoric acid or dehydrated condensed phosphates, and these can have various degrees of neutralization. Among these, the efficiency of introducing a phosphate group is high, the fibrillation efficiency is easily improved in the fibrillation step described later, the cost is low, and it is easy to apply industrially. Sodium salt, potassium salt of phosphate, or ammonium salt of phosphate are preferred, and phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, or ammonium dihydrogen phosphate are more preferred.

The amount of compound A added to the fiber raw material is not particularly limited. For example, when the amount of compound A added is converted to the phosphorus atomic weight, the amount of phosphorus atoms added 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 even more 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 setting the amount of phosphorus atoms added to the fiber raw material to be equal to or less than the above upper limit, it is possible to balance the effect of improving the yield and the cost.

Compound B used in this embodiment is at least one selected from urea and derivatives thereof as described above. Compound B includes, for example, urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, and 1-ethylurea.
From the viewpoint of improving the uniformity of the reaction, compound B is preferably used as an aqueous solution. From the viewpoint of further improving the uniformity of the reaction, it is preferable to use an aqueous solution in which both compound A and compound B are dissolved.

The amount of compound B added to the fiber raw material (absolute dry mass) is 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 between the fiber raw material containing cellulose and compound A, in addition to compound B, for example, amides or amines may be included in the reaction system. Examples of amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine and hexamethylenediamine. Among these, triethylamine in particular is known to work as a good reaction catalyst.

In the phosphate group-introducing step, it is preferable to heat-treat the fiber raw material after adding or mixing the compound A or the like to the fiber raw material. As the heat treatment temperature, it is preferable to select a temperature at which the phosphate group can be efficiently introduced while suppressing the thermal decomposition and 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 even more preferably 130° C. or higher and 200° C. or lower. In addition, for the heat treatment, equipment having various heat media can be used. A drying device, a vacuum drying device, an infrared heating device, a far infrared heating device, or a microwave heating device can be used.

In the heat treatment according to the present embodiment, for example, the compound A is added to a thin sheet-like fiber raw material by a method such as impregnation, and then heated, or the fiber raw material and the compound A are heated while kneading or stirring with a kneader or the like. method can be adopted. This makes it possible to suppress concentration unevenness of the compound A in the fiber raw material and to more uniformly introduce phosphate groups to the surface of the cellulose fibers contained in the fiber raw material. This is because when water molecules move to the surface of the fiber material during drying, the dissolved compound A is attracted to the water molecules by surface tension and similarly moves to the surface of the fiber material (that is, the concentration unevenness of the compound A is It is thought that this is due to the fact that it is possible to suppress the occurrence of

In addition, the heating device used for the heat treatment always removes the moisture retained by the slurry and the moisture generated due to the dehydration condensation (phosphorylation) reaction between the compound A and the hydroxyl groups contained in the cellulose etc. in the fiber raw material. It is preferable that the device can be discharged to the outside of the device system. As such a heating device, for example, an air-blowing oven can be used. By constantly draining the water in the device system, it is possible to suppress the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of phosphorylation, and to suppress the acid hydrolysis of the sugar chains in the fiber. can. Therefore, it is 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 10 seconds or more and 800 seconds or less, after water is substantially removed from the fiber raw material. is more preferable. In the present embodiment, the introduction amount of the phosphate group can be set within a preferable range by setting the heating temperature and the heating time within appropriate ranges.

The step of introducing a phosphate group may be performed at least once, but may be performed repeatedly two or more times. By performing the phosphate group-introducing step two or more times, many phosphate groups can be introduced into the fiber raw material. In the present embodiment, one example of a preferred aspect is the case where the phosphate group introduction step is performed twice.

<Carboxyl Group Introduction Step>
When the fine fibrous cellulose has a carboxyl group, the production process of the fine fibrous cellulose includes a carboxyl group introduction step. In the carboxyl group introduction step, the fiber raw material containing cellulose is subjected to oxidation treatment such as ozone oxidation, oxidation by the Fenton method, TEMPO oxidation treatment, a compound having a carboxylic acid-derived group or a derivative thereof, or a carboxylic acid-derived group. This is done by treating the compound with an acid anhydride or a derivative thereof.

The compound having a carboxylic acid-derived group is not particularly limited. Examples include tricarboxylic acid compounds. Derivatives of compounds having a carboxylic acid-derived group are not particularly limited, but include, for example, imidized acid anhydrides of compounds having a carboxyl group and derivatives of acid anhydrides of compounds having a carboxyl group. Examples of imidized acid anhydrides of compounds having a carboxyl group include, but are not particularly limited to, imidized dicarboxylic acid compounds such as maleimide, succinimide and phthalimide.

The acid anhydride of the compound having a group derived from carboxylic acid is not particularly limited. acid anhydrides; In addition, the acid anhydride derivative of the compound having a carboxylic acid-derived group is not particularly limited. Acid anhydrides in which at least some of the hydrogen atoms are substituted with substituents such as alkyl groups and phenyl groups can be mentioned.

When the TEMPO oxidation treatment is performed in the carboxyl group introduction step, it is preferable to perform the treatment under the condition of pH 6 or more and 8 or less. Such treatment is also referred to as neutral TEMPO oxidation treatment. Neutral TEMPO oxidation treatment includes, for example, sodium phosphate buffer (pH=6.8), pulp as a fiber raw material, and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a catalyst. This can be done by adding sodium hypochlorite as a nitroxy radical, sacrificial reagent. Furthermore, coexistence of sodium chlorite enables efficient oxidation of aldehydes generated in the process of oxidation to carboxyl groups.

Moreover, the TEMPO oxidation treatment may be performed under the condition that the pH is 10 or more and 11 or less. Such treatment is also called alkali TEMPO oxidation treatment. Alkaline TEMPO oxidation treatment can be performed, for example, by adding a nitroxy radical such as TEMPO as a catalyst, sodium bromide as a cocatalyst, and sodium hypochlorite as an oxidizing agent to pulp as a fiber raw material. .

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

<Alkali treatment step (neutralization step)>
When producing fine fibrous cellulose, the fiber raw material may be subjected to alkali treatment between the anion group introduction step and the defibration treatment step described later. The method of alkali treatment is not particularly limited, but includes, for example, a method of immersing the phosphate group-introduced fiber in an alkali 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 alkaline compound because of its high versatility. Moreover, 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 water or a polar solvent including 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 sodium hydroxide solution or an aqueous potassium hydroxide solution is preferable because of its high versatility.

Although the temperature of the alkaline solution in the alkaline treatment step is not particularly limited, it is preferably 5° C. or higher and 80° C. or lower, more preferably 10° C. or higher and 60° C. or lower. The immersion time of the phosphate group-introduced fiber in the alkali solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or more and 30 minutes or less, 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 or less relative to the absolute dry mass of the phosphate group-introduced fiber. is more preferable.

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

<Fibrillation treatment>
By defibrating the anion group-introduced fibers in the fibrillation treatment step, fine fibrous cellulose is obtained. In the defibration treatment process, for example, a fibrillation treatment device can be used. The fibrillation treatment device is not particularly limited, but for example, a high-speed fibrillator, a grinder (stone mill type pulverizer), a high pressure homogenizer, an ultra-high pressure homogenizer, a high pressure impact type pulverizer, a ball mill, a bead mill, a disk refiner, a conical refiner, and a biaxial refiner. 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 defibration equipment, it is more preferable to use a high-speed fibrillation 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 fibrillation treatment step, for example, the phosphate group-introduced fibers are preferably diluted with a dispersion medium to form a slurry. As the dispersion medium, one or more selected from organic solvents such as water and 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, isobutyl alcohol and the like. Examples of polyhydric alcohols include ethylene glycol, propylene glycol and glycerin. Ketones include acetone, methyl ethyl ketone (MEK), and the like. Examples of ethers include diethyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether and the like. Examples of esters include ethyl acetate and butyl acetate. Aprotic polar solvents include dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP) and the like.

The solid content concentration of the fine fibrous cellulose at the defibration treatment can be appropriately set. In addition, the slurry obtained by dispersing the phosphate group-introduced fiber in the dispersion medium may contain solids other than the phosphate group-introduced fiber, such as urea having hydrogen bonding properties.

(metal component)
The fine fibrous cellulose preferably carries at least one metal component selected from Ag, Au, Pt, Pd, Cu and Zn. Such a metal component is preferably at least one selected from Ag, Cu and Zn, and particularly preferably Ag. The metal component described above is supported by, for example, coordinate bonding, hydrogen bonding, or ionic bonding with the phosphate groups contained in the fine fibrous cellulose having phosphate groups. Such binding states can be analyzed by, for example, X-ray photoelectron spectroscopy or infrared spectroscopy.

The content of metal ions contained in 1 g of fine fibrous cellulose is preferably 1.0 to 100 mg, more preferably 5.0 to 80 mg.

<Supporting metal component>
As a method of supporting a metal component on fine fibrous cellulose, a method of contacting fine fibrous cellulose having an anionic group with an aqueous solution of a metal compound can be mentioned. For example, an aqueous solution of a metal compound may be added to a dispersion of fine fibrous cellulose having an anionic group, and an aqueous solution of a metal compound may be added dropwise to a fiber layer containing fine fibrous cellulose having an anionic group. It may be impregnated. As the aqueous solution of the metal compound, for example, an aqueous solution of a metal salt or an organometallic compound can be used. Metal salts include, for example, complexes (complex ions) of metal components, halides, nitrates, sulfates, and acetates. It should be noted that the metal salt is preferably water-soluble.

Although the concentration of the aqueous metal compound solution is not particularly limited, it is preferably 10 parts by mass or more and 80 parts by mass or less, more preferably 30 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of fine fibrous cellulose having an anionic group. The contact time of the metal compound may be adjusted as appropriate. Although the temperature at the time of contact is not particularly limited, 20° C. or higher and 40° C. or lower is preferable. Moreover, the pH of the liquid used for the contact is preferably 2.5 or more and 13 or less.

After contacting the fine fibrous cellulose having an anionic group with the aqueous metal compound solution, a step of reducing the metal compound bound to the fine fibrous cellulose having an anionic group may be provided. As a result, metal components such as metal particles obtained by reduction are carried on the surface of the cellulose fibers. The reduction reaction may be carried out by a known method, but is preferably carried out so as not to cleave the bond between the metal compound and the anion group while reducing the metal compound. In the present embodiment, the reduction treatment can be performed by, for example, a vapor phase reduction method using hydrogen and a liquid phase reduction method using a reducing agent such as an aqueous solution of sodium borohydride. Conditions such as time and temperature in the vapor phase reduction are appropriately adjusted, and the reaction can be carried out, for example, at 50° C. or higher and 60° C. or lower for about 1 hour or longer and 3 hours or shorter. The reaction temperature in the liquid phase reduction is, for example, preferably 4° C. or higher and 40° C. or lower, more preferably room temperature. Note that, in the present embodiment, the treatment for reducing the metal compound may not be performed.

Further, a washing step may be provided after bringing the aqueous metal compound solution into contact with the fine fibrous cellulose having anionic groups. For example, when a nitrate aqueous solution is used as the metal compound aqueous solution, nitrate ions and the like can be removed by providing a washing step.

The sanitary thin paper may contain, as optional components, metal compounds, inorganic compounds, etc., which are not supported by the fine fibrous cellulose. Examples of such optional components include silicon dioxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), iron oxide (Fe ₂ O), yttrium oxide (Y ₂ O ₃ ), indium trioxide (InO), Magnesium oxide (MgO), titanium dioxide (TiO ₂ ), cerium dioxide (CeO ₂ ), manganese tetroxide (Mn ₃ O ₄ ), niobium pentoxide (Nb ₂ O ₅ ), silicon carbide (SiC), boron carbide ( B ₄ C), aluminum nitride (AlN), titanium boride (TiB ₂ ), zeolite, hydroxyapatite, and nano-platinum-silica particles in which metal nanoparticles are bonded to silica. Examples of the metal nanoparticles include gold, silver, copper, aluminum, nickel, cobalt, iron, platinum, ruthenium, zinc, panadium, rhodium, palladium, osmium, and iridium.

(Manufacturing method of sanitary thin paper)
The method for producing a sanitary thin paper preferably includes a step of obtaining a sanitary thin paper containing fine fibrous cellulose supporting a metal component.

The step of obtaining a sanitary thin paper containing fine fibrous cellulose carrying a metal component preferably includes a step of contacting a base paper for sanitary thin paper with a slurry containing fine fibrous cellulose carrying a metal component. Examples of such a step include a step of spraying a slurry containing fine fibrous cellulose supporting a metal component, a step of coating the slurry, and a step of impregnating sanitary thin paper with the slurry. Among them, the step of contacting the metal component-supported fine fibrous cellulose-containing slurry is preferably a step of roll-coating (roll-transferring) the fine fibrous cellulose-containing slurry supporting the metal component onto sanitary thin paper base paper.

When the slurry containing fine fibrous cellulose supporting a metal component is roll-coated, the slurry containing fine fibrous cellulose supporting a metal component is coated so that the solid content after drying is 0.1 g/m ² or more. more preferably 0.5 g/m ² or more, more preferably 1 g/m ² or more, and more preferably 2 g/m ² or more Coating is particularly preferred. Although the upper limit of the coating amount of the fine fibrous cellulose-containing slurry supporting a metal component is not particularly limited, it is preferable to apply the slurry so as to be 50 g/m ² , for example. The solid content concentration of the fine fibrous cellulose-containing slurry supporting the metal component used for coating is preferably 0.1% by mass or more and 10% by mass or less.

A drying step is preferably provided after the above steps (spraying, coating or impregnation step), and the drying method is not particularly limited. The drying step can be carried out, for example, by allowing the substrate to stand in an environment of 23° C. and a relative humidity of 50% for 1 hour or longer.

The step of obtaining the sanitary thin paper containing fine fibrous cellulose carrying a metal component includes the step of obtaining the sanitary thin paper base paper containing fine fibrous cellulose and the step of obtaining the sanitary thin paper base paper followed by the step of contacting with an aqueous metallic compound solution. may be provided. In this case, in the step of obtaining the base paper for sanitary thin paper containing fine fibrous cellulose, for example, slurry containing pulp fibers and slurry containing fine fibrous cellulose can be mixed to make base paper for sanitary thin paper containing fine fibrous cellulose. By making a base paper for sanitary thin paper containing fine fibrous cellulose in this way, a sanitary thin paper with higher strength can be obtained.

In the process of manufacturing the sanitary thin paper, embossing may be applied as necessary. Embossing is performed by passing a two-ply laminated sanitary thin paper web between an embossing roll provided with a convex structure constituting the embossed pattern and a rubber roll to emboss the embossed pattern. Embossing with a desired embossing height can be formed by changing the embossing height of the embossing roll, the pressing amount, and the pressing pressure.

For example, when the sanitary thin paper is toilet paper, it is preferable that a winding step is further provided after the embossing step. In this winding process, winding is performed for a predetermined length so as to satisfy a predetermined product length. Then, the obtained winding roll is cut to a predetermined width. The winding process can be carried out as follows using, for example, a winder having a mandrel shaft. (1) First, the core paper tube is inserted into the mandrel shaft and fixed. (2) Adhesive is applied to the core paper tube, and the starting end of the sanitary thin paper is adhered and fixed to the paper tube. (3) By rotating the mandrel shaft, the sanitary thin paper is wound around the core tube by the length of the product.

The method for producing the boxed tissue paper is not particularly limited, but it can be carried out, for example, as follows.
(1) The tissue paper is paid out from the original tissue paper roll (rolled up), transported to the folding process, and folded.
(2) Cut the folded tissue paper bundle into a predetermined size with a cutter.
(3) Insert the cut tissue bundle into the tissue box (the lid on the side is open).
(4) Adhere the side lids with an adhesive.
A method for producing a pocket tissue is not particularly limited, but for example, it can be carried out as follows.
(1) The tissue paper is paid out from the original tissue paper roll (rolled up), transported to the folding process, and folded.
(2) Cut the folded tissue paper bundle into a predetermined size with a cutter.
(3) Insert the cut tissue bundle into a packaging bag (film).
(4) Seal the packaging bag by heat sealing.

The features of the present invention will be described more specifically below with reference to production examples. The materials, amounts used, proportions, treatment details, treatment procedures, etc. shown in the following production examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed to be limited by the specific examples shown below.

(Example 1)
<Production of fine fibrous cellulose>
[Phosphorylation]
As raw material pulp, softwood kraft pulp manufactured by Oji Paper Co., Ltd. (solid content 93% by mass, basis weight 208 g / m ² sheet, defiberized and Canadian standard freeness (CSF) measured according to JIS P 8121 700 ml) It was used. The raw material pulp was subjected to a phosphorylation treatment as follows. First, a mixed aqueous solution of ammonium dihydrogen phosphate and urea is added to 100 parts by mass (absolute dry mass) of the raw material pulp to obtain 45 parts by mass of ammonium dihydrogen phosphate, 120 parts by mass of urea, and 150 parts by mass of water. A chemical-impregnated pulp was obtained by adjusting as follows. Next, the resulting chemical solution-impregnated pulp was dried in a drier at 105° C. to evaporate water and pre-dried. Thereafter, the pulp was heated for 10 minutes in a blower dryer set at 140° C. to introduce phosphoric acid groups into the cellulose in the pulp to obtain phosphorylated pulp.
Then, the obtained phosphorylated pulp was washed. In the washing treatment, a pulp dispersion liquid obtained by pouring 10 L of ion-exchanged water into 100 g (absolute dry mass) of phosphorylated pulp is stirred so that the pulp is uniformly dispersed, and then filtration and dehydration are repeated. gone. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less.
The washed phosphorylated pulp was further subjected to the phosphorylation treatment and the washing treatment once in this order.

[Neutralization treatment]
Next, the washed phosphorylated pulp was neutralized as follows. First, the washed phosphorylated pulp was diluted with 10 L of ion-exchanged water, and then a 1N sodium hydroxide aqueous solution was added little by little while stirring to obtain a phosphorylated pulp slurry having a pH of 12 or more and 13 or less. . Next, the phosphorylated pulp slurry was dehydrated to obtain neutralized phosphorylated pulp.

Next, the washing treatment was performed on the phosphorylated pulp after the neutralization treatment.
The phosphorylated pulp thus obtained was subjected to infrared absorption spectrum measurement using FT-IR. As a result, absorption due to phosphate groups was observed near 1230 cm ⁻¹ , confirming that phosphate groups were added to the pulp.
In addition, when the obtained phosphorylated pulp was tested and analyzed with an X-ray diffraction device, it was found that the A typical peak was confirmed, confirming that it had cellulose type I crystals.

[Fibrillation treatment]
Ion-exchanged water was added to the obtained phosphorylated pulp to prepare a slurry having a solid content concentration of 2% by mass. This slurry was treated twice at a pressure of 200 MPa with a wet atomization device (Starburst, manufactured by Sugino Machine Co., Ltd.) to obtain a fine fibrous cellulose dispersion (1) containing fine fibrous cellulose. X-ray diffraction confirmed that this fine fibrous cellulose maintained cellulose type I crystals. Further, when the fiber width of the fine fibrous cellulose was measured using a transmission electron microscope, it was 4 nm. The amount of phosphate groups (strongly acidic group amount) measured by the measurement method described later was 1.00 mmol/g.

[Measurement of fiber width]
The fiber width of fine fibrous cellulose was measured by the following method.
The supernatant liquid of the fine fibrous cellulose dispersion (1) obtained by the treatment with a wet atomization apparatus is adjusted so that the concentration of fine fibrous cellulose is 0.01% by mass or more and 0.1% by mass or less. It was diluted with water and added dropwise to a hydrophilized carbon grid film. After drying, it was stained with uranyl acetate and observed with a transmission electron microscope (JEOL-2000EX, manufactured by JEOL Ltd.).

[Measurement of phosphate group content]
The phosphate group content of the fine fibrous cellulose is prepared by diluting the fine fibrous cellulose dispersion (1) containing the target fine fibrous cellulose with ion-exchanged water so that the content becomes 0.2% by mass. The measured fibrous cellulose-containing slurry was treated with an ion-exchange resin and then titrated with an alkali.
The ion-exchange resin treatment is carried out by adding 1/10 by volume of a strongly acidic ion-exchange resin (Amberjet 1024; Organo Co., Ltd., conditioned) to the fibrous cellulose-containing slurry and shaking for 1 hour. , by pouring it onto a mesh with an opening of 90 μm to separate the resin and the slurry.
In addition, titration with an alkali is carried out by adding a 0.1 N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after treatment with an ion exchange resin, and adding 50 μL each time once every 30 seconds. This was done by measuring the change in the value of The amount of phosphate groups (mmol/g) is obtained by dividing the alkali amount (mmol) required in the region corresponding to the first region shown in FIG. 1 among the measurement results by the solid content (g) in the slurry to be titrated. calculated by

[Ion exchange treatment and metal ion support]
The resulting fine fibrous cellulose dispersion (1) was diluted with ion-exchanged water to a content of 0.2% by mass, and then treated with an ion-exchange resin. In the treatment with an ion exchange resin, 1/10 by volume of a strongly acidic ion exchange resin (Ambarjet 1024: Organo Co., Ltd., conditioned) was added to 0.2% by mass of a fine fibrous cellulose dispersion, and the mixture was left for 1 hour. A shaking treatment was performed. After that, the slurry was separated from the resin by pouring it onto a mesh with an opening of 90 μm. Next, silver nitrate (I) was added in an amount equal to twice the amount of phosphate group introduced, and the mixture was stirred for 30 minutes to obtain a fine fibrous cellulose-containing slurry (1) supporting silver ions as a metal component. .

[Washing and slurry preparation]
Next, the resulting slurry (1) was filtered and washed to remove nitrate ions remaining in the system. Specifically, a PTFE membrane filter with a pore size of 1.0 μm is placed on a glass filter, the filter is moistened with IPA, the slurry is poured, and the pressure is reduced at a degree of pressure reduction of −0.09 MPa (absolute vacuum degree of 10 kPa). Filtration was performed. After confirming that a deposit of fine fibrous cellulose supporting silver ions was formed on the PTFE membrane filter, the same amount of water as the original slurry was poured and the process of filtering under reduced pressure was repeated twice. . The obtained deposit of fine fibrous cellulose carrying silver ions was diluted with deionized water so that the content was 1.0% by mass, and a slurry containing washed fine fibrous cellulose carrying silver ions ( 1) was obtained.

<Preparation of toilet paper>
One-ply toilet paper (basis weight: 21.3 g/m ² , thickness: 95 µm) was used as the base paper for toilet paper. Slurry (1) containing fine fibrous cellulose carrying silver ions was roll-coated on one side of base paper for toilet paper so that the solid content after drying was 0.1 g/m ² . It was allowed to stand still for natural drying to obtain a toilet paper containing fine fibrous cellulose.

(Example 2)
Toilet paper was produced in the same manner as in Example 1, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 0.5 g/m ² .

(Example 3)
A toilet paper was prepared in the same manner as in Example 1, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 1.0 g/m ² .

(Example 4)
Toilet paper was produced in the same manner as in Example 1, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 5.0 g/m ² .

(Example 5)
A toilet paper was prepared in the same manner as in Example 1, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 10.0 g/m ² .

(Example 6)
A toilet paper was prepared in the same manner as in Example 1, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was not applied.

(evaluation)
(odor)
A filter paper was placed in a plastic bag (10 L), and the filter paper was impregnated with 1 ml of 10% aqueous ammonia. Next, toilet paper (width 114 mm, length 100 mm) was placed in the plastic bag so as not to contact the filter paper in the plastic bag, and the plastic bag was sealed. Five minutes after sealing, the plastic bag was opened, and the odor inside the plastic bag was evaluated according to the following five grades. Evaluation was performed by 10 subjects, and the average value of the 10 subjects was used as the evaluation value. Table 1 shows the results.
5: Did not feel any odor 4: Almost did not feel odor 3: Slightly felt odor 2: Felt odor 1: Strongly felt odor

(Example 7)
[TEMPO oxidation]
Undried softwood bleached kraft pulp equivalent to 100 parts by weight of dry weight, 1.6 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), and 10 parts by weight of sodium bromide are mixed with 10,000 parts of water. Dispersed in parts by mass. Then, a 13% by mass sodium hypochlorite aqueous solution was added to 3.8 mmol with respect to 1.0 g of pulp to initiate the reaction. During the reaction, a 0.5 M sodium hydroxide aqueous solution was added dropwise to maintain the pH at 10 or more and 10.5 or less, and the reaction was considered completed when no change in pH was observed.

Then, the obtained TEMPO oxidized pulp was washed. The washing treatment is performed by dehydrating the pulp slurry after TEMPO oxidation to obtain a dewatered sheet, pouring 5000 parts by mass of ion-exchanged water, stirring to uniformly disperse, and then filtering and dehydrating repeatedly. rice field. The washing was finished when the electric conductivity of the filtrate became 100 μS/cm or less. Using the obtained carboxyl group-modified cellulose fibers, mechanical treatment was performed in the same manner as in Example 1 to obtain fine fibrous cellulose (2). The average fiber width of the fine fibrous cellulose contained in the fine fibrous cellulose dispersion (2) was 4 nm. In addition, the amount of carboxyl groups measured by the measuring method described later was 1.01 mmol/g.

[Measurement of carboxyl group content]
The carboxyl group content of the fine fibrous cellulose was prepared by diluting the fine fibrous cellulose dispersion (2) containing the target fine fibrous cellulose with ion-exchanged water so that the content was 0.2% by mass. The fibrous cellulose-containing slurry was treated with an ion-exchange resin and then titrated with an alkali for measurement.
The ion-exchange resin treatment is carried out by adding 1/10 by volume of a strongly acidic ion-exchange resin (Amberjet 1024; Organo Co., Ltd., conditioned) to the fibrous cellulose-containing slurry and shaking for 1 hour. , by pouring it onto a mesh with an opening of 90 μm to separate the resin and the slurry.
In addition, titration using an alkali was carried out by adding 50 μL of a 0.1N sodium hydroxide aqueous solution to the fibrous cellulose-containing slurry after treatment with an ion-exchange resin once every 30 seconds, while increasing the electrical conductivity of the slurry. It was carried out by measuring the change in value. The amount of carboxyl groups (mmol/g) is obtained by dividing the alkali amount (mmol) required in the region corresponding to the first region shown in FIG. 2 among the measurement results by the solid content (g) in the slurry to be titrated. Calculated.

[Ion exchange treatment and metal ion support]
The obtained fine fibrous cellulose dispersion (2) was subjected to ion exchange treatment and metal ion loading in the same manner as in Example 1. Washing was carried out in the same manner as in Example 1, and fine fibrous cellulose-containing slurry (2) supporting silver ions was prepared.

<Preparation of toilet paper>
One-ply toilet paper (basis weight: 21.3 g/m ² , thickness: 95 µm) was used as the base paper for toilet paper. The fine fibrous cellulose-containing slurry (2) supporting silver ions was roll-coated on one side of a base paper for toilet paper so that the solid content after drying was 0.1 g/m ² . It was allowed to stand still for natural drying to obtain a toilet paper containing fine fibrous cellulose.

(Example 8)
Toilet paper was produced in the same manner as in Example 7, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 0.5 g/m ² .

(Example 9)
A toilet paper was prepared in the same manner as in Example 7, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 1.0 g/m ² .

(Example 10)
Toilet paper was produced in the same manner as in Example 7, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 5.0 g/m ² .

(Example 11)
Toilet paper was produced in the same manner as in Example 7, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 10.0 g/m ² .

(evaluation)
Examples 7 to 11 were evaluated by the method of odor evaluation described above.

It was confirmed that toilet paper containing fine fibrous cellulose exhibits a deodorant effect. Especially in Examples 1 to 5, the toilet paper containing fine fibrous cellulose having a phosphate group exhibited a high deodorizing effect.

(Example 12)
On one side of one-ply base paper for toilet paper (basis weight: 21.3 g/m ² , thickness: 95 μm), a fine fibrous cellulose-containing slurry (1) supporting silver ions was dried, and the solid content after drying was 0.1 g/m. ² was applied by roll coating. After drying with a drier, the toilet paper was wound into a roll around a core paper tube (outer diameter: 38 mm). In this way, a toilet roll (winding length: 50 m, winding diameter: 110 mm) containing one ply of toilet paper was obtained. When winding into a roll, the surface coated with the fine fibrous cellulose-containing slurry (1) supporting silver ions was wound on the outside.

(Example 13)
When wound into a roll, the toilet roll was carried out in the same manner as in Example 12, except that the surface coated with the fine fibrous cellulose-containing slurry (1) supporting silver ions was on the inside. got

(evaluation)
Examples 12 and 13 were evaluated by the method of odor evaluation described above.

(Example 14)
<Preparation of tissue paper>
Two-ply tissue paper (basis weight of 1 ply: 17.5 g/m ² , thickness of 2 plies: 119.7 µm) was used as the tissue paper base paper. The fine fibrous cellulose-containing slurry (1) supporting silver ions was roll-coated on one side of a base paper for tissue paper so that the solid content after drying was 0.1 g/m ² . It was allowed to stand still for natural drying to obtain a tissue paper containing fine fibrous cellulose.

(Example 15)
A tissue paper was prepared in the same manner as in Example 14, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 0.5 g/m ² .

(Example 16)
A tissue paper was prepared in the same manner as in Example 14, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 1.0 g/m ² .

(Example 17)
A tissue paper was prepared in the same manner as in Example 14, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 5.0 g/m ² .

(Example 18)
A tissue paper was prepared in the same manner as in Example 14, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was applied so that the solid content after drying was 10.0 g/m ² .

(Example 19)
A tissue paper was prepared in the same manner as in Example 14, except that the fine fibrous cellulose-containing slurry (1) supporting silver ions was not applied.

(evaluation)
(odor)
A filter paper was placed in a plastic bag (10 L), and the filter paper was impregnated with 1 ml of 10% aqueous ammonia. Next, tissue paper (2 plies, width 100 mm, length 100 mm) was placed in the plastic bag so as not to contact the filter paper in the plastic bag, and the plastic bag was sealed. Five minutes after sealing, the plastic bag was opened, and the odor inside the plastic bag was evaluated according to the following five grades. Evaluation was performed by 10 subjects, and the average value of the 10 subjects was used as the evaluation value. Table 1 shows the results.
5: Did not feel any odor 4: Almost did not feel odor 3: Slightly felt odor 2: Felt odor 1: Strongly felt odor

(Example 20)
<Preparation of tissue paper>
Two-ply tissue paper (basis weight of 1 ply: 17.5 g/m ² , thickness of 2 plies: 119.7 µm) was used as the tissue paper base paper. The fine fibrous cellulose-containing slurry (2) supporting silver ions was roll-coated on one side of a tissue base paper so that the solid content after drying was 0.1 g/m ² . It was allowed to stand still for natural drying to obtain a tissue paper containing fine fibrous cellulose.

(Example 21)
A tissue paper was prepared in the same manner as in Example 20, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 0.5 g/m ² .

(Example 22)
A tissue paper was prepared in the same manner as in Example 20, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 1.0 g/m ² .

(Example 23)
A tissue paper was prepared in the same manner as in Example 20, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 5.0 g/m ² .

(Example 24)
A tissue paper was prepared in the same manner as in Example 20, except that the fine fibrous cellulose-containing slurry (2) supporting silver ions was applied so that the solid content after drying was 10.0 g/m ² .

(evaluation)
Examples 20 to 24 were evaluated by the method of odor evaluation described above.

It was confirmed that tissue paper containing fine fibrous cellulose exhibits a deodorizing effect. Especially in Examples 14 to 19, the tissue paper containing fine fibrous cellulose having a phosphoric acid group exhibited a high deodorizing effect.

Claims (4)

containing fibrous cellulose with a fiber width of 1000 nm or less ,
The fibrous cellulose has an anionic group,
The anion group is at least one selected from a phosphate group and a substituent derived from a phosphate group,
The sanitary thin paper , wherein the fibrous cellulose carries Ag as a metal component . The sanitary thin paper according to claim 1 , wherein the content of said fibrous cellulose is 0.05 to 15 g/m ² . Toilet paper comprising the sanitary thin paper according to claim 1 or 2 . A tissue paper comprising the sanitary thin paper according to claim 1 or 2 .

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