Antiviral sheet containing cellulose fibers

Abstract

An object of the present invention is to provide an antiviral sheet containing cellulose fibers and having excellent antiviral activity. [Solution] The present invention provides an antiviral sheet containing cellulose fibers. The antiviral sheet of the present invention has an antiviral activity value (Mv) of 2.0 or more against influenza virus or feline calicivirus, measured according to JIS L 1922:2016 (Testing methods for antiviral activity of textile products).

Description

Technical Field

[0001] The present invention relates to an antiviral sheet. More specifically, it relates to an antiviral sheet containing cellulose fibers.

Background Art

[0002] Functional sheets obtained by imparting a functional agent to a sheet-like substrate are used in various industrial fields. Examples of functions generally include deodorization, antibacterial, heat resistance, moisture resistance, weather resistance, solvent resistance, abrasion resistance, electromagnetic wave shielding, etc. Examples of applications include packaging materials (paper containers, cardboard, resin films, etc.), building materials (wallpapers, decorative papers, floor papers, etc.), daily necessities (deodorizing materials, aromatic materials), industrial supplies (filters, wipers, etc.), medical products (masks, etc.), clothing, and other paper products (cards, renderers, etc.). Among them, deodorization and antibacterial functions are often required in many industrial fields. Many.

[0003] In addition to the above functions, the performance required for the functional sheet also includes, as mechanical properties of the sheet, tensile strength, tear strength, burst strength, and, if necessary, air permeability, printability, etc.

[0004] Various techniques have been proposed to impart deodorization and antibacterial functions to a sheet-like substrate. For example, in Patent Documents 1 and 2, an aqueous solution of either a silicon compound or an aluminum compound, which are constituent components of zeolite, is impregnated into a hydrophilic polymer substrate such as cellulose fibers, and a basic substance is mixed with the other aqueous solution and further impregnated therewith to support zeolite inside the cellulose fibers. An inorganic porous crystal-hydrophilic polymer composite has been proposed, and it is further disclosed that an antibacterial effect and a deodorizing effect can be imparted by supporting a metal on the zeolite. In addition, Patent Document 3 discloses a cellulose fiber structure in which an aqueous solution containing a silicon compound and a basic substance and an aqueous solution containing an aluminum compound and a basic substance are impregnated into a fiber structure, and then wet-heated to react the silicon compound and the aluminum compound inside the cellulose fiber to produce zeolite, which is a silica-alumina porous body. Further, it is disclosed that antibacterial and antifungal properties can be imparted by introducing metal ions into this silica-alumina porous body.

[0005] In addition, Patent Document 4 discloses an antibacterial cellulose fiber containing one or more silver-based antibacterial agents selected from silver zeolite, silver zirconium phosphate, silver calcium phosphate, and silver-soluble glass.

[0006] In addition, Patent Document 5 discloses a paper base material containing oxidized pulp, wherein the amount of carboxyl groups in the oxidized pulp is 1.0 mmol / g to 2.0 mmol / g based on the absolute dry weight of the oxidized pulp, and the paper base material is for a functional sheet having deodorizing properties and the like.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, what is described in Patent Documents 1 to 4 and the like is merely a simple mixture of cellulose fibers and an inorganic compound containing a metal component, and the cellulose fibers and the inorganic compound containing a metal component are not chemically strongly bonded. That is, since the inorganic compound containing a metal component does not form a physical and chemical network like a fiber, when a functional sheet is manufactured using this, mechanical properties as a base material such as tensile strength and tear strength decrease, and there is also a problem that the inorganic compound containing a metal component falls off from the base material. In addition, conventional functional sheets have a problem that their antiviral functions and the like decrease when placed in a high-humidity environment or when wetted. Here, the wetted state means, for example, a state in which the mass ratio of moisture is 100% or more with respect to a certain mass after drying of the non-woven fabric. In view of such a situation, an object of the present invention is to provide an antiviral sheet containing cellulose fibers, which has excellent antiviral activity.

Means for Solving the Problems

[0009] Although not limited thereto, the present invention includes the following aspects. [1] An antiviral sheet containing cellulose fibers, The above sheet having an antiviral activity value (Mv) of 2.0 or more against influenza virus or feline calicivirus measured based on JIS L 1922:2016 (Test method for antiviral properties of textile products). [2] The sheet according to [1], wherein the cellulose fibers include oxidized cellulose fibers having a carboxyl group or a carboxylate group as cellulose fibers having an anion group; and / or carboxyalkylated cellulose fibers having a carboxyalkyl group. [3] The sheet according to [2], wherein the amount of anion groups in the cellulose fibers having an anion group is 0.01 to 3.0 mmol / g. [4] The sheet according to any one of [1] to [3], wherein the cellulose fiber contains Cu and / or Ag as metal ions and / or metal particles, and the content of the metal ions and / or metal particles in the sheet is 6.3 mg / g or less. [5] The sheet according to any one of [1] to [4], wherein the cellulose fiber contains Cu as metal ions and / or metal particles. [6] The sheet according to any one of [1] to [5], containing LBKP and / or waste paper pulp. [7] The sheet according to any one of [1] to [6], wherein the total content of the metal ions and / or metal particles in the sheet is 0.20 to 6.3 mg / g. [8] The sheet according to any one of [1] to [7], having an antiviral activity value (Mv) of 3.0 or more against influenza virus or feline calicivirus. [9] The sheet according to any one of [1] to [8], wherein the sheet is paper.

[10] The sheet according to [9], having a clear coating layer on one or both sides.

[11] The basis weight of the sheet is 20 to 250 g / m 2 The sheet according to any one of [1] to

[10] .

[12] A method for manufacturing the sheet according to any one of [1] to

[11] , including the step of forming a sheet from a slurry containing cellulose fibers.

[13] The method according to

[12] , wherein the slurry further contains LBKP and / or waste paper pulp.

[14] The method according to

[12] or

[13] , wherein the sheet comprises 1 to 15% by weight of the cellulose fiber.

[15] The slurry contains calcium carbonate, the basis weight of the sheet is 20 to 250 g / m 2 The sheet is made by using a paper machine, and the method according to

[12] to

[14] . [Advantages of the Invention]

[0010] According to the present invention, an antiviral sheet containing cellulose fibers and having excellent antiviral properties can be provided. According to the present invention, since the functional components contributing to antiviral activity and the like remain firmly in the sheet, functions such as antiviral activity are fully exhibited.

Mode for Carrying Out the Invention

[0011] The sheet containing cellulose fibers according to the present invention is a single-layer or multi-layer sheet having antiviral properties. Specifically, the antiviral sheet according to the present invention has an antiviral activity value (Mv) of 2.0 or more against influenza virus or feline calicivirus measured based on JIS L 1922:2016 (Test Method for Antiviral Properties of Textile Products), and it is more preferable that the antiviral activity value is 2.5 or more or 3.0 or more.

[0012] In addition to antiviral properties, the antiviral sheet according to the present invention may have one or more other functions. Examples of the functions of the antiviral sheet according to the present invention include, for example, deodorization, antibacterial, heat resistance, moisture resistance, weather resistance, solvent resistance, abrasion resistance, electromagnetic wave shielding, etc. In a preferred embodiment of the present invention, the antiviral sheet has a deodorization and / or antibacterial function.

[0013] The use of the antiviral sheet according to the present invention is not particularly limited, and it can be used for any application that requires an antiviral function. Examples of the uses of the antiviral sheet include, for example, packaging materials (paper containers, cardboard, resin films, wrapping papers, etc.), building materials (wallpapers, decorative papers, floor papers, etc.), sanitary products (diapers, menstrual products, wipes, masks, towels, gauze, cotton swabs, etc.), daily necessities (deodorants, fragrances, food filters, clean filters, lunch mats, tray masks, tablecloths, drain nets, cooking papers, cooking sheets, ash draining sheets, kitchen towels, dishcloths, aprons, pot holders, toilet seat covers, toilet floor splash guards, foot wiping mats, wet tissues, disposable slippers, carpet substrates, shoe insoles, suit covers, handbags, condensation sheets, book covers, vacuum cleaner paper packs, stickers, bookmarks, notebooks, notebook covers, pet sheets, disposable sheets, pillow covers, futon covers, wiping sheets, etc.), industrial supplies (industrial filters, industrial wipes, automotive interior materials, etc.), medical products (masks, protective clothing, surgical gowns (caps, aprons, tops and bottoms), antibacterial mats, cleaning cloths, medical tapes, etc.), clothing (disposable underwear, etc.), gardening and agricultural materials (gardening sheets, agricultural sheets, seedbed sheets, fruit bags, etc.), headrest covers (for bullet trains and automobiles), and other paper products (calendars, etc.).

[0014] The antiviral sheet according to the present invention may have a single-layer structure or a multi-layer structure. However, in the case of a multi-layer structure, at least one layer or more needs to contain cellulose fibers. In addition, the cellulose fibers carrying metal ions and / or metal particles described later exhibit an excellent antiviral function regardless of which layer they are contained in. However, since viruses generally adhere to the outermost layer of the sheet, from the viewpoint of efficiently expressing the antiviral function, it is preferable that the cellulose fibers carrying metal ions and / or metal particles are contained in the outermost layer of the sheet.

[0015] The antiviral sheet according to the present invention contains cellulose fibers, and the cellulose fibers preferably have anionic groups on the surface and contain one or more metal ions and / or metal particles selected from the group of elements of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn, and Cu. The anionic group is preferably a carboxyl group or a carboxylate group, and it is preferable that metal ions are ionically bonded. In the present invention, it is preferable to have at least one layer containing cellulose fibers carrying metal ions and / or metal particles (hereinafter also referred to as "metal-containing cellulose fibers"). From the viewpoints of high activity and safety, it is preferable to contain Cu and / or Ag as the metal ions, and it is more preferable to contain Cu. Ag and Cu are highly safe compared to Hg and can be suitably used for paper applications that are often directly touched by hand. Also, Cu is known to be less affected by halogens, temperature, etc. and stably exhibit its effects compared to Ag. The paper of the present invention containing pulp carrying metal, particularly Cu ions / or Cu particles of the present invention can be used in any environment and application.

[0016] Raw materials other than the metal-containing cellulose fibers are not particularly limited, and known raw materials can be used. As an example, it may contain one or more other materials such as cellulose fibers not carrying metal ions or metal particles (hereinafter also referred to as "general cellulose fibers"), synthetic fibers, resins, and inorganic substances. The sheet of the present invention may contain a filler. The content of the filler in the sheet is not particularly limited, but it is preferably in a range not exceeding 20% by weight of the sheet weight, and can also be 10% by weight or less or 5% by weight or less. Examples of the filler include heavy calcium carbonate, light calcium carbonate, silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, talc, clay, mica, asbestos, calcium silicate, montmorillonite, pentonite, graphite, aluminum powder, molybdenum sulfide, and the like. Other materials are not particularly limited, but for example, a bulking agent, a dry paper strength improver, a wet paper strength improver, a drainage improver, a yield improver, a dye, a sizing agent, a sulfate band, etc. may be used as necessary. The total content of other materials other than the filler is preferably not more than 10% by weight of the sheet weight.

[0017] Also, the method for manufacturing the sheet is not particularly limited, and a known method can be used. For example, either a method of discharging water in which the raw material is dispersed and dehydrating it by pressure or heat (so-called wet method), or a method of discharging the raw material in a dry state and forming a sheet by pressure or heat in the same manner (so-called dry method) may be used. Since cellulose fibers are hydrophilic, it is preferable to form the sheet by the wet method. In the present invention, the sheet can also be manufactured by mixing the above cellulose fibers with a pulp slurry (paper stock) in the same manner as a normal paper sheet and using the sample for papermaking. Known papermaking machines such as a fourdrinier papermaking machine, a twin-wire papermaking machine, and a cylinder-type papermaking machine can be used for papermaking, and the papermaking conditions are not limited either. Further, the antiviral sheet according to the present invention may be subjected to a known surface treatment such as calendering as necessary. A known treatment apparatus can be used for the surface treatment, and the conditions are not limited either. The antiviral sheet according to the present invention may be provided with a coating layer (clear coating layer) that does not contain a pigment, if necessary, on the surface of the sheet. The sheet of the present invention preferably has a clear coating layer on one or both sides of the sheet, and more preferably has a clear coating layer containing at least starches. By having a clear coating layer, when the sheet of the present invention is paper, it is possible to obtain paper that is particularly excellent in smoothness, surface strength, and printing suitability. Also, although the reason is not clear, the sheet of the present invention has excellent antiviral activity and antibacterial and deodorizing functions even when the sheet surface is covered with a clear coating layer. The coating amount of the clear coating layer is preferably 0.01 to 3.0 g / m in terms of solid content per side, 2 more preferably 0.1 to 2.0 g / m. 2 The clear coating can be formed, for example, by applying a coating solution onto the sheet using a coater (coating machine) such as a size press, a gate roll coater, a premetallizing size press, a curtain coater, or a spray coater. The solid content concentration of the clear coating solution is preferably 2 to 14% by weight from the viewpoints of boiling and coating amount adjustment. The B-type viscosity (30 °C, 60 rpm) at a solid content concentration of 5% by weight is preferably 5 to 450 mPa·s, and more preferably 10 to 300 mPa·s. In the present invention, starch refers to a mixture composed of amylose and amylopectin, Generally, the mixing ratio varies depending on the plant that is the raw material of the starch. In the present invention, starches also include high molecular compounds derived from starch. Examples of such high molecules include those obtained by modifying, processing, etc. starch. Examples of starches include starches such as raw starch, oxidized starch, esterified starch, cationized starch, self-modified starch produced by thermochemical modification or enzymatic modification in a paper mill using acetylated tapioca starch as a raw material, modified starches such as aldehyde starch and hydroxyethylated starch. The clear coating layer of the present invention can use, for example, cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose, modified alcohols such as polyacrylamide, polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, and acetoacetyl polyvinyl alcohol, styrene-butadiene copolymers, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, polyacrylate esters, etc., and two or more kinds can be used in combination. Also, for the purpose of enhancing sizing properties, it is possible to use in combination surface sizing agents such as styrene sizing agents, olefin sizing agents, acrylate sizing agents, styrene-acrylic sizing agents, and cationic sizing agents. In the present invention, various auxiliaries usually compounded in ordinary clear coating, such as a dispersant, thickener, water retention agent, defoaming agent, water resistance agent, coloring agent, conductive agent, etc., are appropriately used as necessary. The basis weight of the anti-viral sheet according to the present invention is not particularly limited, and a general range can be set as necessary, but it is preferably in the range of 10 to 1000 g / m 2 and more preferably in the range of 10 to 300 g / m 2 and even more preferably in the range of 20 to 250 g / m 2 is also acceptable. If the basis weight is greater than 1000 g / m 2 , the sheet may have problems such as inferior bendability and cutability characteristic of the sheet. When the sheet has a multi-layer structure, it is preferable that the outermost base paper layer contains the metal ions and / or metal particles of the present invention. Also, when the basis weight of each layer is 10 g / m 2 or more, it is preferable from the viewpoint of manufacturing a sheet that is uniform and has a minimum strength in handling during manufacturing.

[0018] The thickness of the antiviral sheet is preferably in the range of 20 to 500 μm, more preferably in the range of 30 to 200 μm. When the sheet has a multilayer structure, it is preferable from the viewpoint of manufacturing a uniform sheet that the thickness of each layer is 20 μm or more. The density of the sheet is not particularly limited.

[0019] When the antiviral sheet according to the present invention has a multilayer structure, after manufacturing each layer one by one, they may be laminated by a known method, or they may be formed while sequentially laminating each layer. Further, the sheet may be manufactured in a so-called simultaneous multilayer method in which multiple layers are formed at once while simultaneously discharging the raw materials of each layer. The method of adhering each layer is not particularly limited, and a known method can be used. For example, a method using an adhesive, a method of fusing the layers together by passing between hot rolls or applying hot air, etc. can be mentioned. When the antiviral sheet according to the present invention has a multilayer structure, the outermost layer may be laminated in one or more layers, or it may have an adhesive layer for adhering to another base material, like a so-called adhesive label sheet, on the outermost layer. Further, it may be a simple laminate of single-layer sheets, or one or more layers may have a three-dimensional structure like cardboard.

[0020] The antiviral sheet according to the present invention may be printed on the outermost layer as necessary.

[0021] When the antiviral sheet according to the present invention contains cellulose fibers carrying metal ions and / or metal particles, it preferably contains a total of 0.20 mg / g or more, more preferably 0.25 mg / g or more, still more preferably 0.30 mg / g or more, and most preferably 0.60 mg / g or more of metal ions and metal particles per 1 g of the sheet. Also, it preferably contains a total of 6.3 mg / g or less, and may be 5.0 mg / g or less or 4.0 mg / g or less of metal ions and metal particles per 1 g of the sheet. The total content of metal ions and / or metal particles in the sheet per 1 g of the sheet is 0 By setting it to 6.3 mg / g or more and 20 mg / g or less, a sheet excellent in antiviral function and the like can be easily obtained, and an increase in environmental load due to excessive metal ions and / or metal particles and coloring of the sheet can be suppressed.

[0022] The contents of metal ions and metal particles in the antiviral sheet can be measured (quantified) by, for example, inductively coupled plasma optical emission spectrometry (ICP - OES).

[0023] Also, the content of the metal - containing cellulose fiber is preferably 0.5% by weight or more based on the antiviral sheet. If the content of the metal - containing cellulose fiber is too small, a sufficient antiviral function may not be imparted. The upper limit value of the above content is not particularly limited and can be appropriately adjusted according to the degree of antiviral, deodorizing, antibacterial functions, etc. required, and it may be 100% by weight. The content of the metal - containing cellulose fiber may be, for example, 1 - 80% by weight, 2 - 60% by weight, 3 - 40% by weight, etc. Also, as described above, since the content of the metal - containing cellulose fiber is preferably 0.5% by weight or more based on the antiviral sheet, the content of the general cellulose fiber in the antiviral sheet is preferably 99.5% by weight or less. The lower limit value of the content of the general cellulose fiber is not particularly limited, and it may not contain general cellulose fiber.

[0024] The antiviral sheet according to the present invention comprises cellulose fibers. There is no particular limitation on the type of cellulose fibers in the present invention, and any type can be used as required. Also, two or more types of these cellulose fibers may be mixed and used in any ratio. The origin of the cellulose fiber is not particularly limited, and examples include cellulose fibers derived from plants, animals, algae, microorganisms, etc. Among them, cellulose fibers derived from plants or microorganisms are preferred, and cellulose fibers derived from plants are particularly preferred. Examples of plant-derived cellulose fibers include wood, bamboo, hemp, jute, kenaf, agricultural waste, pulp (softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, wastepaper pulp, etc.). Examples of animal-derived cellulose fibers include cellulose fibers derived from tunicates, and examples of microorganism-derived cellulose fibers include cellulose fibers derived from acetic acid bacteria (Acetobacter).

[0025] The number-average fiber diameter and number-average fiber length of the cellulose raw material used in the present invention are not particularly limited, and those having arbitrary number-average fiber diameters and number-average fiber lengths can be used as needed. Also, two or more types of cellulose fibers having different number-average fiber diameters and number-average fiber lengths may be mixed and used in any ratio. As an example, in the case of softwood kraft pulp (NBKP), which is one of general pulps, the number-average fiber diameter is about 30 to 60 μm, and the number-average fiber length is about 3 to 5 mm. In the case of hardwood bleached kraft pulp (LBKP), the number-average fiber diameter is about 10 to 30 μm, and the number-average fiber length is about 1 to 2 mm. Further, when the sheet of the present invention is paper, it is preferable to contain LBKP and / or wastepaper pulp as cellulose fibers. LBKP and wastepaper pulp have relatively short fiber lengths, and by including these pulps, paper excellent in smoothness can be obtained, and the paper thus obtained is excellent in surface properties and printing suitability (especially the feel of the printed surface). (1) Modification of cellulose fibers Cellulose fibers have three hydroxyl groups per glucose unit and can be subjected to various chemical modification treatments. In the present invention, it is preferable to perform a chemical modification treatment having anionic groups after the treatment. Examples of cellulose fibers having anionic groups introduced therein include oxidized cellulose fibers having a carboxyl group or a carboxylate group, and phosphoric acid esterified cellulose having a phosphoric acid group Examples include s-fibers, phosphite esterified cellulose fibers having phosphite groups, sulfonated cellulose fibers having sulfate groups, and the like. In the present invention, in order to introduce metal ions or metal particles into at least a part of the cellulose fibers in the steps described later, it is preferable to perform modification (oxidation) to introduce carboxyl groups or carboxylate groups into at least a part of the cellulose fibers. In this specification, the anionic groups introduced into the cellulose fibers may also be referred to as acid groups.

[0026] Here, the carboxyl group refers to a group represented by -COOH, and the carboxylate group refers to a group represented by -COO-. The counter ion of the carboxylate group is not particularly limited. When metal particles are formed through an ionic bond with the carboxylate group as described later, this metal ion serves as the counter ion.

[0027] The amount of anionic groups (acid groups) in cellulose fibers having anionic groups (acid groups) can be measured, for example, by the following method. Prepare 60 ml of a 0.5 mass% slurry (aqueous dispersion) of a cellulose fiber sample having anionic groups (acid groups), add 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.5, then dropwise add 0.05 N sodium hydroxide aqueous solution and measure the electrical conductivity until the pH reaches 11. Measure the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid where the change in electrical conductivity is gentle. Next, calculate the amount of anionic groups [mmol / g] in the cellulose fibers having anionic groups (acid groups) using the following formula. In the formula, x is a value corresponding to the valence of the acid group, which is 1 for carboxyl groups, carboxylate groups, phosphite groups, and sulfonic acid groups, and 2 for phosphate groups. a [ml] × 0.05 / weight of cellulose fibers having anionic groups (acid groups) [g] / x

[0028] In the case of carboxyalkylated cellulose fibers having carboxyalkyl groups, when quantifying the amount of anionic groups by carboxyalkylation treatment, the following method can be used. (1) Weigh accurately about 2.0 g of carboxymethylated cellulose (absolute dry) and place it in a 300 mL conical flask with a stopper. (2) Add 100 mL of special grade concentrated nitric acid to 1000 mL of methanol to obtain 100 mL of a nitric acid - methanol solution, shake for 3 hours to convert carboxymethyl cellulose salt (carboxymethylated cellulose) into hydrogen - type carboxymethylated cellulose. (3) Weigh accurately 1.5 - 2.0 g of hydrogen - type carboxymethylated cellulose (absolute dry) and place it in a 300 mL conical flask with a stopper. (4) Moisten the hydrogen - type carboxymethylated cellulose with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. (5) Using phenolphthalein as an indicator, back - titrate the excess NaOH with 0.1 N H2SO4. (6) Calculate the carboxyalkyl substitution degree (DS) by the following formula: A = [(100×F’-(0.1 N H2SO4)(mL)×F)×0.1] / (mass of absolute dry hydrogen - type carboxyalkylated cellulose (g)) DS = 0.162×A / (1 - 0.058×A) A: Volume (mL) of 1 N NaOH required for neutralizing 1 g of hydrogen - type carboxyalkylated cellulose F': Factor of 0.1 N NaOH F: Factor of 0.1 N H2SO4

[0029] Hereinafter, a method for introducing anionic groups into glucose units on the surface of cellulose fibers will be described.

[0030] (1 - 1) Oxidation In the present invention, the method of modifying (oxidizing) to introduce a carboxyl group or a carboxylate group into cellulose fibers is not particularly limited as long as the modified cellulose fibers contain a carboxyl group or a carboxylate group, and a known method can be used. As an example, there is a method of oxidizing a cellulose raw material in water using an oxidizing agent in the presence of an N-oxyl compound and a substance selected from the group consisting of bromides, iodides or mixtures thereof. According to this method, the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface is selectively oxidized to produce a group selected from the group consisting of an aldehyde group, a carboxyl group, and a carboxylate group. The concentration of the cellulose raw material during the reaction is not particularly limited, but is preferably 5% by weight or less.

[0031] The N-oxyl compound refers to a compound capable of generating a nitroxyl radical. Examples of the nitroxyl radical include 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). As the N-oxyl compound, any compound can be used as long as it promotes the target oxidation reaction.

[0032] The amount of the N-oxyl compound used is not particularly limited as long as it is a catalytic amount capable of oxidizing cellulose fibers. For example, with respect to 1 g of absolutely dry cellulose, 0.01 mmol or more is preferable, and 0.02 mmol or more is more preferable. The upper limit is preferably 10 mmol or less, more preferably 1 mmol or less, and still more preferably 0.5 mmol or less. Therefore, the amount of the N-oxyl compound used is preferably 0.01 to 10 mmol, more preferably 0.01 to 1 mmol, and still more preferably 0.02 to 0.5 mmol with respect to 1 g of absolutely dry cellulose.

[0033] A bromide is a compound containing bromine, and examples thereof include alkali metal bromides that can dissociate and ionize in water, such as sodium bromide. Further, an iodide is a compound containing iodine, and examples thereof include alkali metal iodides. The amount of the bromide or iodide used may be selected within a range that can promote the oxidation reaction. The total amount of the bromide and iodide is preferably 0.1 mmol or more, more preferably 0.5 mmol or more, per 1 g of absolutely dry cellulose. The upper limit is preferably 100 mmol or less, more preferably 10 mmol or less, still more preferably 5 mmol or less. Therefore, the total amount of the bromide and iodide is preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, still more preferably 0.5 to 5 mmol, per 1 g of absolutely dry cellulose.

[0034] The oxidizing agent is not particularly limited, and examples thereof include halogens, hypohalous acids, halous acids, perhalic acids, their salts, halogen oxides, peroxides, etc. Among them, hypohalous acids or their salts are preferred, hypochlorous acid or its salts are more preferred, and sodium hypochlorite is still more preferred because they are inexpensive and have a low environmental impact.

[0035] The amount of the oxidizing agent used is preferably 0.5 mmol or more, more preferably 1 mmol or more, still more preferably 3 mmol or more, per 1 g of absolutely dry cellulose. The upper limit is preferably 500 mmol or less, more preferably 50 mmol or less, still more preferably 25 mmol or less. Therefore, the amount of the oxidizing agent used is preferably 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, still more preferably 1 to 25 mmol, most preferably 3 to 10 mmol, per 1 g of absolutely dry cellulose.

[0036] When using an N-oxyl compound, the amount of the oxidizing agent used is preferably 1 mol or more per 1 mol of the N-oxyl compound. The upper limit is preferably 40 mol. Therefore, the amount of the oxidizing agent used is preferably 1 to 40 mol per 1 mol of the N-oxyl compound.

[0037] The conditions such as pH and temperature during the oxidation reaction are not particularly limited. Generally, even under relatively mild conditions, the oxidation reaction proceeds efficiently. The reaction temperature is preferably 4°C or higher, more preferably 15°C or higher. The upper limit is preferably 40°C or lower, more preferably 30°C or lower. Therefore, the temperature is preferably 4 - 40°C, and may be about 15 - 30°C, that is, room temperature.

[0038] The pH of the reaction solution is preferably 8 or higher, more preferably 10 or higher. The upper limit is preferably 12 or lower, more preferably 11 or lower. Therefore, the pH of the reaction solution is preferably 8 - 12, more preferably about 10 - 11. Usually, as carboxyl groups are generated in cellulose with the progress of the oxidation reaction, the pH of the reaction solution tends to decrease. Therefore, in order to make the oxidation reaction proceed efficiently, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution within the above range. The reaction medium during oxidation is preferably water for reasons such as ease of handling and difficulty in causing side reactions.

[0039] The reaction time in oxidation can be appropriately set according to the degree of progress of oxidation, and is usually 0.5 hours or more. The upper limit is usually 6 hours or less, preferably 4 hours or less. Therefore, the reaction time in oxidation is usually 0.5 - 6 hours, for example, about 0.5 - 4 hours.

[0040] The oxidation may be carried out in two or more stages. For example, the oxidized cellulose obtained by filtration after the completion of the first-stage reaction can be oxidized again under the same or different reaction conditions, so that it can be efficiently oxidized without being inhibited by the reaction of by-produced sodium chloride in the first-stage reaction.

[0041] As another example of the method for introducing a carboxyl group or carboxylate group (oxidation), there is a method of oxidizing by ozone treatment. By this oxidation reaction, at least the hydroxyl groups at the 2nd and 6th positions of the glucopyranose ring constituting cellulose are oxidized, and decomposition of the cellulose chain occurs.

[0042] Ozone treatment is usually carried out by bringing a gas containing ozone into contact with a cellulose raw material. The ozone concentration in the gas is preferably 50 g / m 3 or more. The upper limit is preferably 250 g / m 3 or less, and more preferably 220 g / m 3 or less. Therefore, the ozone concentration in the gas is preferably 50 - 250 g / m 3 and more preferably 50 - 220 g / m 3 .

[0043] The ozone addition amount is preferably 0.1 part by weight or more, and more preferably 5% by weight or more, based on 100% by weight of the solid content of the cellulose raw material. The upper limit is usually 30% by weight or less. Therefore, the ozone addition amount is preferably 0.1 - 30% by weight, and more preferably 5 - 30% by weight, based on 100% by weight of the solid content of the cellulose raw material.

[0044] The ozone treatment temperature is usually 0°C or higher, preferably 20°C or higher. The upper limit is usually 50°C or lower. Therefore, the ozone treatment temperature is preferably 0 - 50°C, and more preferably 20 - 50°C. The ozone treatment time is usually 1 minute or more, preferably 30 minutes or more. The upper limit is usually 360 minutes or less. Therefore, the ozone treatment time is usually about 1 - 360 minutes, and preferably about 30 - 360 minutes. When the ozone treatment conditions are within the above ranges, it is possible to prevent the cellulose from being excessively oxidized and decomposed, and the yield of oxidized cellulose becomes good.

[0045] Furthermore, post-oxidation treatment may be performed on the resultant obtained after ozone treatment using an oxidizing agent. The oxidizing agent used for the post-oxidation treatment is not particularly limited, and examples include chlorine-based compounds such as chlorine dioxide and sodium chlorite; oxygen, hydrogen peroxide, persulfuric acid, peracetic acid, etc. As a method for the post-oxidation treatment, for example, these oxidizing agents are dissolved in water or a polar organic solvent such as alcohol A method of dissolving to prepare an oxidant solution and immersing a cellulose raw material in the oxidant solution can be mentioned.

[0046] The amount of anionic groups of oxidized cellulose fibers having carboxyl groups or carboxylate groups is preferably 0.01 to 3.0 mmol / g, more preferably 0.20 to 2.2 mmol / g. When the anionic groups are less than 0.01 mmol / g, in the step of supporting metal ions or metal particles on the cellulose fibers described later, the amount of metal particles present on the surface of the cellulose fibers is not sufficient, and the antiviral, deodorizing, and antibacterial functions may be inferior. On the other hand, when the anionic groups exceed 3.0 mmol / g, aggregation of metal particles may occur, the antiviral, deodorizing, and antibacterial functions may be inferior, and cellulose cleavage may easily occur as a side reaction during the oxidation reaction, resulting in a decrease in yield. The amount of anionic groups (carboxyl groups, carboxylate groups) contained in the oxidized cellulose fibers can be adjusted by controlling oxidation conditions such as the addition amount of the oxidant and the reaction time.

[0047] (1-2) Etherification As for the etherification, for the convenience of introducing metal ions into the cellulose fibers in the subsequent process, any method may be used as long as the functional groups after the reaction contain carboxyl groups or carboxylate groups, and known methods can be used. Examples include carboxyalkyl etherifications such as carboxymethyl (ether)ification, carboxyethyl (ether)ification, carboxypropyl (ether)ification, carboxybutyl (ether)ification, and carboxyphenyl (ether)ification. As an example among these, the method of carboxymethyl ification will be described below.

[0048] The method of carboxymethylation is not particularly limited, and known methods can be used. For example, a method of mercerizing a cellulose raw material as a starting material and then etherifying it can be mentioned. A general solvent is used during the carboxymethylation reaction. Examples of the solvent include water, alcohol (e.g., lower alcohol), and a mixed solvent thereof. Examples of the lower alcohol include methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butyl alcohol, isobutyl alcohol, and tertiary butanol.

[0049] The mixing ratio of the lower alcohol in the mixed solvent is usually 60% by weight or more and 95% by weight or less, preferably 60 to 95% by weight. The amount of the solvent is usually 3 times by weight based on the cellulose raw material. The upper limit is not particularly limited, but it is 20 times by weight. Therefore, the amount of the solvent is preferably 3 to 20 times by weight.

[0050] Mercerization is usually carried out by mixing a starting material and a mercerizing agent. Examples of the mercerizing agent include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. The amount of the mercerizing agent used is preferably 0.5 times mol or more, more preferably 1.0 times mol or more, and even more preferably 1.5 times mol or more per anhydroglucose residue of the starting material. The upper limit is usually 20 times mol or less, preferably 10 times mol or less, and more preferably 5 times mol or less. Therefore, 0.5 to 20 times mol is preferred, 1.0 to 10 times mol is more preferred, and 1.5 to 5 times mol is even more preferred.

[0051] The reaction temperature of mercerization is usually 0°C or higher, preferably 10°C or higher. The upper limit is usually 70°C or lower, preferably 60°C or lower. Therefore, the reaction temperature is usually 0 to 70°C, preferably 10 to 60°C. The reaction time is usually 15 minutes or more, preferably 30 minutes or more. The upper limit is usually 8 hours or less, preferably 7 hours or less. Therefore, it is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours.

[0052] The etherification reaction is usually carried out by adding a carboxymethylating agent to the reaction system after mercerization. Examples of the carboxymethylating agent include sodium monochloroacetate. The addition amount of the carboxymethylating agent is preferably usually 0.05 times mol or more, more preferably 0.5 times mol or more, and even more preferably 0.8 times mol or more per glucose residue of the cellulose raw material. The upper limit is usually 10.0 times mol or less, preferably 5 times mol or less, and more preferably 3 times mol or less. Therefore, it is preferably 0.05 to 10.0 times mol, more preferably 0.5 to 5 times mol, and even more preferably 0.8 to 3 times mol.

[0053] The reaction temperature is usually 30°C or higher, preferably 40°C or higher, and the upper limit is usually 90°C or lower, preferably 80°C or lower. Therefore, the reaction temperature is usually 30 to 90°C, preferably 40 to 80°C. The reaction time is usually 30 minutes or longer, preferably 1 hour or longer. The upper limit is usually 10 hours or shorter, preferably 4 hours or shorter. Therefore, the reaction time is usually 30 minutes to 10 hours, preferably 1 hour to 4 hours. During the carboxymethylation reaction, the reaction solution may be stirred as necessary.

[0054] When modifying the cellulose raw material by carboxymethylation, the degree of carboxymethyl substitution per anhydroglucose unit in the obtained carboxymethylated cellulose fiber is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.10 or more. The upper limit is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.35 or less. Therefore, the degree of carboxymethyl substitution is preferably 0.01 to 0.50, more preferably 0.05 to 0.40, and even more preferably 0.10 to 0.30.

[0055] (1-3) Esterification In the present invention, any method for introducing a phosphate group or a phosphite group into the cellulose fiber (esterification) may be used, and known methods can be employed.

[0056] Phosphoric acid esterified cellulose fibers having a phosphate group and phosphorous acid esterified cellulose fibers having a phosphite group are cellulose fibers esterified with a compound having a phosphate group or a phosphite group. Examples of the compound having a phosphate group or a phosphite group include phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, esters and salts thereof. These compounds are low-cost and easy to handle.

[0057] Specific examples of the compound having a phosphate group or a phosphite group include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium metaphosphate, phosphorous acid, sodium hydrogen phosphite, ammonium hydrogen phosphite, potassium hydrogen phosphite, sodium dihydrogen phosphite, sodium phosphite, lithium phosphite, potassium phosphite, magnesium phosphite, calcium phosphite, triethyl phosphite, triphenyl phosphite, pyrophosphorous acid, etc. Among them, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, ammonium salts of phosphoric acid, phosphorous acid, sodium salts of phosphorous acid, potassium salts of phosphorous acid, and ammonium salts of phosphorous acid are preferred because of high esterification efficiency and easy industrial application. Sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydrogen phosphite, and sodium dihydrogen phosphite are more preferred. The compound having a phosphate group or a phosphite group may be used alone or in combination of two or more.

[0058] The esterification reaction is, for example, carried out on a cellulose raw material with a compound having a phosphate group or a phosphite group. It is carried out by reacting the compound. As a method for reacting a cellulose raw material with a compound having a phosphate group or a phosphite group, for example, there are a method of mixing a powder or an aqueous solution of a compound having a phosphate group or a phosphite group with a cellulose raw material, and a method of adding an aqueous solution of a compound having a phosphate group or a phosphite group to a slurry of a cellulose raw material. Among these, a method of mixing an aqueous solution of a compound having a phosphate group or a phosphite group with a cellulose raw material or its slurry is preferred because the uniformity of the reaction is enhanced and the esterification efficiency is increased. From the viewpoint of enhancing the efficiency of introducing a phosphate group or a phosphite group, the pH of the aqueous solution of the compound having a phosphate group or a phosphite group is preferably 7 or less, and more preferably 3 to 7 from the viewpoint of suppressing hydrolysis.

[0059] The lower limit of the addition amount of the compound having a phosphate group or a phosphite group is preferably 0.2 parts by weight or more, more preferably 1 part by weight or more in terms of phosphorus atom per 100 parts by weight of the cellulose raw material. By being in this range, the yield of phosphoric acid esterified cellulose fiber and phosphorous acid esterified cellulose fiber is likely to be improved. On the other hand, the upper limit is preferably 500 parts by weight or less, more preferably 400 parts by weight or less. By being in this range, it can be efficiently obtained at a yield commensurate with the addition amount of the compound having a phosphate group or a phosphite group.

[0060] When reacting a cellulose raw material with a compound having a phosphate group or a phosphite group, a basic compound may be further added to the reaction system. As a method for adding a basic compound to the reaction system, for example, there are a method of adding it to a slurry of a cellulose raw material, a method of adding it to an aqueous solution of a compound having a phosphate group or a phosphite group, or a method of adding it to a slurry of a cellulose raw material and a compound having a phosphate group or a phosphite group. The basic compound is not particularly limited, but a nitrogen-containing compound showing basicity is preferred. Note that "showing basicity" generally means that an aqueous solution of a basic compound exhibits a pink to red color in the presence of a phenolphthalein indicator, or the pH of an aqueous solution of a basic compound is greater than 7.

[0061] The nitrogen-containing compound exhibiting basicity is not particularly limited as long as it exhibits the effects of the present invention. Among them, compounds having an amino group are preferable. For example, urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine can be mentioned. Among these, urea is preferable because of its low cost and easy handling.

[0062] The addition amount of the basic compound is preferably 2 to 1000 parts by weight, more preferably 100 to 700 parts by weight. The reaction temperature is preferably 0 to 95°C, more preferably 30 to 90°C. The reaction time is not particularly limited, but is usually about 1 to 600 minutes, preferably 30 to 480 minutes. When the reaction conditions are within any of these ranges, it is possible to prevent excessive introduction of phosphate groups and phosphite groups into cellulose and make it difficult to dissolve, and the yield of phosphoric acid esterified cellulose fibers and phosphite esterified cellulose fibers is likely to be improved.

[0063] After reacting the cellulose raw material with a compound having a phosphate group or a phosphite group, a suspension is usually obtained. The suspension is preferably dehydrated as necessary and heat-treated after dehydration. Thereby, hydrolysis of the cellulose raw material can be suppressed. The heating temperature is preferably 100 to 170°C, and it is more preferably heated at 130°C or lower (more preferably 110°C or lower) while water is contained during the heat treatment, and after removing the water, heated at 100 to 170°C.

[0064] It is preferable to perform a washing treatment such as washing with cold water after boiling for the phosphoric acid esterified cellulose fibers and phosphite esterified cellulose fibers.

[0065] In the phosphoric acid esterified cellulose fibers and phosphite esterified cellulose fibers, the anionic groups (phosphate groups, phosphite groups) contained in the phosphoric acid esterified cellulose fibers and phosphite esterified cellulose fibers are preferably 0.1 to 3.5 mmol / g.

[0066] (1-4) Sulfonation Sulfonated cellulose fibers are cellulose fibers sulfonated with a compound having a sulfate group. Examples of the compound having a sulfuric acid group include sulfuric acid, sulfamic acid, chlorosulfonic acid, sulfur trioxide, esters and salts thereof. These compounds are low-cost and easy to handle.

[0067] In the present invention, sulfamic acid is preferably used. Sulfamic acid not only has lower solubility in cellulose compared to sulfuric anhydride or sulfuric acid aqueous solution, but also has a low acidity, so that the degree of polymerization can be maintained. In addition, there are no handling restrictions on sulfuric anhydride or sulfuric acid aqueous solution, which is strongly acidic and highly corrosive, and it is not designated as a specified substance under the Air Pollution Control Law, so the environmental load is small.

[0068] The amount of sulfamic acid used can be appropriately adjusted in consideration of the amount of anionic groups (sulfate groups) introduced into the cellulose fibers. Sulfamic acid can be used, for example, preferably in an amount of 0.01 to 50 mol, more preferably 0.1 to 30 mol, per 1 mol of glucose units in the cellulose molecule.

[0069] (2) Loading of Metal Ions and / or Metal Particles onto Cellulose Fibers In the present invention, by further containing metal ions and / or metal particles of one or more metal elements selected from the group consisting of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn and Cu in cellulose fibers containing anionic groups, particularly carboxyl groups or carboxylate groups, excellent antiviral, deodorizing and antibacterial functions are exhibited. Among them, by using one or more ions selected from the group consisting of Ag and Cu, the antiviral, deodorizing and antibacterial functions are further improved, which is preferable, and more preferably Cu ions and / or metal particles. Cellulose fibers having anionic groups have a chemical bond between metal ions or metal particles and cellulose fibers. Therefore, when contained in a sheet, the metal component is difficult to desorb from the sheet, and the mechanical properties such as tensile strength are also good, and the performance and strength do not decrease.

[0070] As a method for supporting the above metal ions on the above cellulose fiber, it is not particularly limited. For example, a previously prepared dispersion of cellulose fiber and an aqueous solution of a metal compound may be mixed, or a dispersion containing cellulose fiber may be applied onto a substrate to form a film, and an aqueous solution of a metal compound may be dropped onto the film for impregnation. At this time, the film may remain fixed on the substrate or may be in a state of being peeled off from the substrate. Although the detailed mechanism is unknown, it is presumed that by these methods, metal ions derived from the metal compound form an ionic bond or coordinate by anion exchange with sodium ions that have already been ionically bonded to anionic groups such as carboxylate groups, thereby adding metal ions to the cellulose fiber. This anion exchange is considered to occur due to the difference in ionization tendency between metal ions.

[0071] Here, the aqueous solution of the metal compound is an aqueous solution of a metal salt. Examples of the metal salt include complexes (complex ions), halides, nitrates, sulfates, and acetates.

[0072] The concentration of the aqueous solution of the metal compound is not particularly limited, but is preferably 0.2 to 2.2 mmol per 1 g of cellulose fiber, and more preferably 0.4 to 1.8 mmol. The time for contacting the metal compound may be adjusted appropriately.

[0073] The temperature at the time of contacting the metal compound is not particularly limited, but is preferably in the range of 2 to 50 °C. Also, the pH of the liquid at the time of contacting is not particularly limited, but since it becomes difficult for metal ions to bind to carboxyl groups when the pH is low, it is preferably in the range of 7 to 13, and particularly preferably in the range of pH 8 to 12.

[0074] In the present invention, the effect is achieved by introducing metal ions into the cellulose fibers as described above, but some of the metal ions may be reduced to form metal particles. If necessary, it is also possible to partially form metal particles on the surface of the cellulose fibers by reducing some of the metal ions bound to the obtained metal ion-containing cellulose fibers by adding a reducing agent or the like. However, it is preferable from the viewpoint of antiviral, antibacterial, and deodorizing functions to use the entire amount of the metal compound as metal ions without carrying out any special reduction treatment.

[0075] The mechanism by which metal particles are generated in the cellulose fibers by reducing the metal compound in the metal-containing cellulose fibers obtained above is not clear, but is presumed to be as follows. The metal compound or ions derived from the metal compound in the metal compound-containing cellulose fibers are reduced to metal by the reduction reaction. At this time, the generated metal is supported on the surface of the cellulose fibers. Metals generated in the same manner and adjacent to each other are integrated to form particles. Meanwhile, metal compounds and the like that exist in the vicinity of the cellulose fibers but are not bonded to the cellulose fibers are also reduced to generate metal. This metal quickly integrates with the metal on the surface of the cellulose fibers to form metal particles.

[0076] The reduction reaction may be carried out by a known method, but is preferably carried out while reducing the metal compound without cleaving the bond between the metal compound and the cellulose fiber. Examples of such reduction methods include a gas phase reduction method using hydrogen and a liquid phase reduction method using a reducing agent such as an aqueous solution of sodium borohydride. The conditions such as time and temperature in the gas-phase reduction are appropriately adjusted. For example, the reaction may be carried out at 50 to 60 °C for about 1 to 3 hours. The gas-phase reduction reaction is preferably carried out in a state where the oxidized cellulose fiber does not contain water or a solvent. In the reduction reaction, the membrane may remain fixed on the substrate or may be in a state peeled off from the substrate. In the case of liquid-phase reduction, a membrane can be obtained from the above dispersion liquid, and this can be subjected to the reduction reaction with or without drying. Further, the dispersion liquid can be directly subjected to the liquid-phase reduction reaction without drying. The reaction temperature in the liquid-phase reduction is preferably 4 to 40 °C, more preferably room temperature.

[0077] The average particle diameter of the metal particles is determined from a transmission electron microscope image or X-ray diffraction. In the present invention, the average particle diameter of the metal particles is preferably in the range of 1 to 50 nm when determined from a transmission electron microscope image. Specifically, as a method for determining the average particle diameter from a transmission electron microscope image, a transmission electron microscope image of cellulose fibers is prepared, and from the image, the equivalent circle diameters of the primary particles of a plurality of metal particles are determined and averaged.

[0078] That the cellulose fiber contains metal ions and / or metal particles can be confirmed by a scanning electron microscope image and ICP emission spectrometry of an extract with a strong acid. That is, the presence of metal ions cannot be confirmed in a scanning electron microscope image, while it can be confirmed by ICP emission spectrometry that the metal is contained. On the other hand, for example, when the above metal is reduced from an ion and exists as metal particles, the metal particles can be confirmed in a scanning electron microscope image, so the presence or absence of metal ions can be determined. Also, the presence or absence of metal ions can be determined by a scanning electron microscope image and elemental mapping. That is, metal ions cannot be confirmed in a scanning electron microscope image, but the presence of metal ions can be confirmed by performing elemental mapping.

[0079] In the step of supporting the metal ions or metal particles, the former with respect to the cellulose fiber The content of the metal ions and / or metal particles is preferably in the range of 10 to 100 mg / g in total, more preferably in the range of 15 to 80 mg / g, and particularly preferably in the range of 20 to 60 mg / g. If the total is less than 10 mg / g, the anti-viral, deodorizing, and antibacterial functions may be inferior. On the other hand, if the total exceeds 100 mg / g, metal ions are likely to elute during production, and the load of wastewater treatment may increase.

[0080] (3) Refining The cellulose fiber in the present invention may be subjected to at least one refining treatment before the modification treatment and after the metal loading treatment. However, it is preferable to perform the refining treatment before the metal loading treatment because the fiber can be efficiently fibrillated without aggregation. Here, the refining treatment is a treatment that applies mechanical shear force to the fiber. By the refining treatment, a part of the cellulose fiber is fibrillated, and the surface area increases. Generally, the bond between fibers during drying can be strengthened. In the present invention, particularly for the metal-containing cellulose fiber, the anti-viral, deodorizing, and antibacterial effects after loading the metal ions and / or metal particles can be further enhanced by performing the refining treatment. On the other hand, if the refining treatment is performed excessively and the cellulose fiber is over-refined, the yield will decrease when forming paper by blending with pulp, or it will not remain in the paper, and the anti-viral, deodorizing, and antibacterial functions will decrease, so it is not preferable. As an index of the degree of refining, the Canadian Standard Freeness (CSF) can be used. Specifically, when the freeness (CSF) is less than 30 ml, the anti-viral, deodorizing, and antibacterial functions will decrease due to the decrease in the yield of the sheet. When the CSF) exceeds 600 ml, the fibrillation is insufficient and the anti-viral, deodorizing, and antibacterial functions may decrease. Thus, by setting the freeness (CSF) of the cellulose fiber to 30 to 600 ml, the anti-viral, deodorizing, and antibacterial functions are improved.

[0081] The apparatus used for beating is not particularly limited, and known apparatuses can be arbitrarily used. Examples of beating apparatuses include those that act on pulp fibers with metal or blades around a rotating shaft, such as refiners, beaters, PFI mills, kneaders, and dispersers, those that rely on the friction between pulp fibers, and apparatuses such as high-pressure homogenizers, ultra-high-pressure homogenizers, nanomizers, various mills, and stone mortar grinders.

[0082] Also, prior to beating or, if necessary, prior to the dispersion treatment performed before beating, a pretreatment may be carried out as needed. Examples of the pretreatment include, for example, mixing, stirring, emulsification, and dispersion, and it may be carried out using a known apparatus (e.g., a high-speed shear mixer).

[0083] In the present invention, cellulose fibers may be nanofibrillated. At the nanofibrillated site, the surface area increases, and the antiviral, deodorizing, and antibacterial functions can be improved. On the other hand, if the fibers are completely nanofibrillated, the fibers are completely dissociated, the yield decreases when manufacturing by blending with pulp, the fibers do not remain in the paper (do not stay), and the effects of the cellulose fibers are reduced. Here, nanofibrillation means making cellulose fibers into fibers with a fiber diameter of 100 nm or less. To nanofibrillate, known apparatuses similar to those used for beating can be arbitrarily used.

Examples

[0084] Hereinafter, the present invention will be described in more detail with specific examples, but the present invention is not limited to the following specific examples. In this specification, unless otherwise specified, concentrations and the like are based on weight, and numerical ranges are described as including their endpoints. standards, and numerical ranges are described as including their endpoints.

[0085] Experiment 1. Production of cellulose oxide fibers carrying copper ions (cellulose oxide fibers carrying Cu ions) 5.00 g (bone dry) of bleached unbeat pulp (brightness 85%) derived from softwood was placed in T EMPO (manufactured by Sigma Aldrich) 39 mg (0.05 mmol per 1 g of dry cellulose) and sodium bromide 514 mg (1.0 mmol per 1 g of dry cellulose) were added to 500 ml of an aqueous solution, and the mixture was stirred until the pulp was uniformly dispersed. Subsequently, an aqueous sodium hypochlorite solution was added to the reaction system so that the sodium hypochlorite concentration became 5.5 mmol / g, and the oxidation reaction was initiated at room temperature. During the reaction, the pH in the system decreased, but a 3M aqueous sodium hydroxide solution was sequentially added to adjust the pH to 10. The reaction was terminated when the sodium hypochlorite was consumed and the pH in the system no longer changed (time required for the oxidation reaction: about 90 minutes). After filtering the reaction mixture through a glass filter, washing with a sufficient amount of water and filtration were repeated twice to obtain oxidized cellulose fibers impregnated with water (solid content: 10% by mass, pulp yield: 90%, amount of carboxyl groups: 1.68 mmol / g). Water was added to the obtained oxidized cellulose fibers to form a dispersion with a solid content concentration of 2%, and the pH was adjusted to 9.0. Subsequently, CuCl2 (manufactured by Fujifilm Wako Pure Chemical Corporation) was added, and it was added with stirring so that the concentration per 1 g of oxidized cellulose fibers became 1.0 mmol / g, and the mixture was further stirred for 30 minutes to incorporate Cu ions into the oxidized cellulose fibers. Thereafter, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts and obtain Cu ion-supported oxidized cellulose fibers impregnated with water (solid content: 30% by mass). The content of metal ions in the obtained Cu ion-supported oxidized cellulose fibers was 43.8 mg / g, and the Canadian Standard Freeness (CSF) of the Cu ion-supported oxidized cellulose fibers was 500 ml.

[0086] Experiment 2. Production of antiviral sheet [Sheet 1] As the cellulose fiber, deinked wastepaper pulp derived from waste newspapers (manufactured by Nippon Paper Industries Co., Ltd., CSF: 300 ml) was used, and the Cu ion-supported oxidized cellulose fiber produced in Experiment 1 was blended so as to be 1% by weight based on the total cellulose fiber. While stirring at 500 rpm using a Three-One motor, 30% by weight (solid content) of light calcium carbonate, 0.7% by weight (solid content) of polyaluminum chloride, and 0.05% by weight (solid content) of paper strength improver were sequentially added to 100% by weight of the cellulose fiber to prepare a pulp slurry. From the obtained pulp slurry, a sheet with a basis weight of 60 g / m 2 , a paper thickness of 120 μm, and an ash content of 14% was manufactured using a round hand sheet machine. [Sheet 2] A size press solution containing 5% by weight of oxidized starch (manufactured by Nippon Cornstarch Co., Ltd., SK20) was prepared. This size press solution was coated on both sides of Sheet 1 and dried by a conventional method (coating amount: 1 g / m in total for both sides 2 ). [Sheet 3] On one side of Sheet 2, using an RI-I type printing machine (manufactured by Ishikawajima Industries Co., Ltd.), Vantain Echo ink (manufactured by Toyo Ink Co., Ltd.) was solid printed so that the ink film thickness concentration immediately after printing was 1.0. [Sheet 4] A sheet was manufactured in the same manner as Sheet 1, except that the Cu ion-supported oxidized cellulose fiber was blended so as to be 3% by weight based on the total cellulose fiber. [Sheet 5] A sheet was manufactured in the same manner as Sheet 1, except that the Cu ion-supported oxidized cellulose fiber was blended so as to be 5% by weight based on the total cellulose fiber. [Sheet 6] A sheet was manufactured in the same manner as Sheet 2, except that the Cu ion-supported oxidized cellulose fiber was blended so as to be 5% by weight based on the total cellulose fiber. [Sheet 7] A sheet was manufactured in the same manner as Sheet 3, except that the Cu ion-supported oxidized cellulose fiber was blended so as to be 5% by weight based on the total cellulose fiber. [Sheet 8] LBKP (manufactured by Nippon Paper Industries Co., Ltd., CSF: 480 ml) was used as the cellulose fiber, and the Cu ion-loaded oxidized cellulose fiber produced in Experiment 1 was blended therein at 4% by weight based on the total amount of the cellulose fiber. With respect to 100% by weight of the cellulose fiber, 0.16% by weight of a sizing agent, 1.50% by weight of a sulfate binder, and 0.70% by weight of cationized starch were sequentially added to prepare a pulp slurry. From the obtained pulp slurry, paper was made using a paper machine at a speed of 250 m / min, and calendering treatment was performed. The basis weight was 71.0 g / m 2 , and the paper thickness was 105 μm to produce a sheet. [Sheet 9] A sheet was produced in the same manner as Sheet 8, except that the Cu ion-loaded oxidized cellulose fiber was blended at 7% by weight based on the total amount of the cellulose fiber. [Sheet 10] A sheet was produced in the same manner as Sheet 8, except that the Cu ion-loaded oxidized cellulose fiber was blended at 10% by weight based on the total amount of the cellulose fiber. [Sheet 11] (Comparative Example) A sheet was produced in the same manner as Sheet 1, except that the Cu ion-loaded oxidized cellulose fiber was not used. [Sheet 12] (Comparative Example) A sheet was produced in the same manner as Sheet 8, except that the Cu ion-loaded oxidized cellulose fiber was not used. [Sheet 13] (Comparative Example) A sheet was produced in the same manner as Sheet 8, except that the Cu ion-loaded oxidized cellulose fiber was blended at 1% by weight based on the total amount of the cellulose fiber.

[0087] Experiment 3. Evaluation of antiviral sheet For the obtained antiviral sheets, antiviral functions and the like were evaluated by the following method. [Copper content] The content (mg / g) of metal ions and metal particles per 1 g of the sheet was measured by ICP optical emission spectrometry (ICP-OES) according to the following procedure. (1) Before measurement, the measurement sample was dried (50 °C, 1 day). (2) Weigh 0.1 g of the dried measurement sample and put it into a 50-ml beaker. (3) Pipette 10 ml of concentrated nitric acid and add it to the beaker containing the measurement sample to prepare a measurement sample solution (10-fold dilution). (4) Let it stand for 30 minutes, then pass it through a syringe filter to remove fiber components from the measurement sample solution (filtration). (5) Pipette 1 ml of the filtered measurement sample solution and add it to a test tube containing 49 ml of distilled water (50-fold dilution). (6) Close the lid of the test tube tightly and shake it to stir. (7) Use ICP-OES (manufactured by Agilent Technology, ICP-OES 5110) to measure (quantify) the contents of metal ions and metal particles. (8) Based on the quantitative results (ppb) by ICP-OES, calculate the contents of metal ions and metal particles per gram of the sheet (mg / g) according to the following formula. (Quantitative result by ICP-OES (ppb) × 10 × 50) / (Weight of the measurement sample (g) ) × 1000 / 1000000000 [Antiviral function] The antiviral function test was carried out according to JIS L 1922:2016, and the antiviral activity value (Mv) was calculated. The weight of the sheet used in the test was 0.4 g, and the following two types were used as test viruses. · Influenza virus (H3N2, ATCC VR―1679) · Feline calicivirus (Strain: F-9 ATCC VR-782)

[0088] [Deodorizing function] The deodorizing function test was carried out for ammonia according to the method of the SEK Mark fiber product certification standard (JEC301, Fiber Evaluation Technology Council) with a test material size of 100 cm 2 . The deodorizing function was evaluated according to the following criteria. ◎ (Very good): The reduction rate of ammonia is 80% or more. ○ (Good): The ammonia reduction rate is 70% or more and less than 80%. × (Bad): The ammonia reduction rate is less than 70%.

[0089] [Antibacterial function] According to JIS L1902 "Test Method for Antibacterial Properties and Antibacterial Effects of Textile Products", a qualitative test by the halo method was carried out. Specifically, an agar medium containing Escherichia coli was prepared, and a 5 cm × 5 cm test piece of the antiviral sheet was placed on it. After culturing at 37 °C for 17 hours, the presence or absence of a "growth inhibition zone" of the test bacteria formed around the sample was confirmed. The antibacterial function was evaluated according to the following criteria. ○: A growth inhibition zone was observed and it has an antibacterial function. ×: No growth inhibition zone was observed and it has no antibacterial function.

Table 1

Table 2

Claims

1. A method for producing an antiviral printing paper having an antiviral activity value (Mv) of 2.0 or more against influenza virus or feline calicivirus measured based on JIS L 1922:2016 (Test method for antiviral properties of textile products), comprising: (a) Cellulose fibers derived from wood containing Cu ions and / or Cu particles, (b) Wood-derived pulp containing LBKP and / or waste paper pulp, A step of papermaking using a Fourdrinier paper machine, a twin-wire paper machine or a cylinder paper machine from a slurry containing the same, Using a size press, a gate roll coater, a pre-metallizing size press, a curtain coater or a spray coater, 3.0 g / m per side ２ The step of providing the following clear coating layer on one side or both sides, A step of performing calendering treatment, The method as described above, wherein the content of Cu ions and / or Cu particles in the antiviral printing paper is 0.20 to 2.55 mg / g.

2. The method according to claim 1, wherein the cellulose fibers include oxidized cellulose fibers having a carboxyl group or a carboxylate group; and / or carboxyalkylated cellulose fibers having a carboxyalkyl group, as cellulose fibers having an anionic group.

3. The method according to claim 1, wherein the cellulose fibers include carboxyalkylated cellulose fibers having a carboxyalkyl group, as cellulose fibers having an anionic group.

4. The method according to claim 2 or 3, wherein the amount of anionic groups in the cellulose fibers having an anionic group is 0.01 to 3.0 mmol / g.

5. The method according to any one of claims 1 to 4, having an antiviral activity value (Mv) of 3.0 or more against influenza virus or feline calicivirus.

6. The basis weight of the antiviral printing paper is 20 to 250 g / m ２ The method according to any one of claims 1 to 5, wherein the thickness of the antiviral printing paper is 20 to 500 μm.

7. The method according to any one of claims 1 to 6, wherein the slurry contains polyaluminum chloride, aluminum sulfate or cationized starch.

8. The method according to any one of claims 1 to 7, wherein the clear coating layer contains starch.

9. A calendered antiviral printing paper having an antiviral activity value (Mv) of 2.0 or more against influenza virus or feline calicivirus measured based on JIS L 1922:2016 (Test method for antiviral properties of textile products), comprising: (a) Cellulose fibers derived from wood containing Cu ions and / or Cu particles, (b) Wood-derived pulp containing LBKP and / or waste paper pulp, On one or both sides of the base paper comprising, 3.0 g / m per side ２ The antiviral printing paper having the following clear coating layer, wherein the content of Cu ions and / or Cu particles in the antiviral printing paper is 0.20 to 2.55 mg / g.

10. The antiviral printing paper according to claim 9, wherein the cellulose fiber in (a) contained in the antiviral printing paper is 1 to 15% by weight.

11. The antiviral printing paper according to claim 9 or 10, wherein the base paper contains a filler.

12. The base paper contains calcium carbonate, and the basis weight of the antiviral printing paper is 20 to 81.0 g / m ２ The antiviral printing paper according to any one of claims 9 to 11, wherein the basis weight is as defined above.

Images