Method for producing coloring material

Abstract

To provide a method for producing a color material dyed in high concentration and derived from a biomass nanomaterial.SOLUTION: A method for producing a color material, comprising: mercerizing a biomass nanomaterial; and mixing the mercerized biomass nanomaterial with a dye to dye the mercerized biomass nanomaterial.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a colorant derived from a biomass nanomaterial. [Background technology]

[0002] Biomass materials are organic resources derived from living organisms and are abundant in nature. There is growing interest in the effective use of biomass materials from the perspectives of reducing environmental impact, utilizing high-functionality biomass materials, and achieving the Sustainable Development Goals (SDGs). Representative biomass materials include polysaccharides such as cellulose and amylose, which are abundantly obtained from plants and animals. Polysaccharides are attracting attention as a substitute for general-purpose plastics, and as functional materials that are biocompatible, biodegradable, and physiologically active.

[0003] In recent years, biomass nanomaterials, which are biomass materials reduced to the nano level, have been attracting particular attention. Biomass nanomaterials have unique properties and are environmentally friendly. Cellulose nanofibers, in particular, have been the subject of intensive research.

[0004] Cellulose nanofibers can be obtained, for example, by defibrating natural fibers obtained from plant resources to nanometer sizes. Cellulose nanofibers form a three-dimensional network structure in water and exhibit characteristic rheological behavior, including thixotropy, dispersion stability, and emulsion stability. Cellulose nanofibers can impart viscosity and disperse fine particles in water. Therefore, aqueous dispersions of cellulose nanofibers are widely used. Aqueous dispersions of cellulose nanofibers are used as water retention agents, humectants, shape retention agents, dispersion stabilizers, emulsion stabilizers, and thickeners in the fields of cosmetics, pharmaceuticals, quasi-drugs, food, and paints. Patent Document 1 discloses an aqueous ink composition for writing instruments containing plant-derived cellulose nanofibers that have not been subjected to an oxidation treatment.

[0005] The use of dyed cellulose nanofibers has also been investigated. Patent Document 2 discloses a molding material in which cellulose nanofibers dyed with a reactive dye are dispersed in a thermoplastic resin. Patent Document 3 discloses a writing instrument ink containing water-insoluble cellulose dyed with a reactive dye, a direct dye, or an acid dye. Patent Document 4 discloses an inkjet ink containing cellulose nanofibers dyed with a reactive dye, a direct dye, or a sulfide dye. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-105907 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-166818 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-125135 [Patent Document 4] Japanese Patent Application Publication No. 2019-085472 Summary of the Invention [Problem to be solved by the invention]

[0007] The dyed cellulose nanofibers described in the above Patent Documents 2 to 4 have a pale color and are insufficient for use as a coloring material in writing instruments or inkjet applications.

[0008] An object of the present invention is to provide a method for producing a highly dyed colorant derived from biomass nanomaterials. [Means for solving the problem]

[0009] In order to achieve the above object, the method for producing a colorant of the present invention comprises the steps of: [1] Mercerizing biomass nanomaterials; and mixing the mercerized biomass nanomaterial with a dye to dye the mercerized biomass nanomaterial.

[0010] [2] The method for producing a coloring material according to [1] above, wherein the biomass nanomaterial comprises at least one selected from the group consisting of cellulose nanofibers, cellulose nanocrystals, chitosan nanofibers, chitin nanofibers, and silk nanofibers.

[0011] [3] The method for producing a colorant according to [2] above, wherein the cellulose nanofibers comprise at least one selected from the group consisting of mechanically defibrated cellulose nanofibers, chemically defibrated cellulose nanofibers, and bacterial cellulose nanofibers.

[0012] [4] The method for producing a colorant according to any one of the above [1] to [3], wherein the dye comprises at least one selected from the group consisting of reactive dyes, vat dyes, direct dyes, acid dyes, basic dyes, and fluorescent dyes.

[0013] [5] The mercerization is carried out by contacting the biomass nanomaterial with a mercerizing agent in an aqueous solvent; The method for producing a colorant according to any one of [1] to [4] above, wherein the amount of the mercerizing agent used is 0.1 g or more and 40 g or less per 1 g of the dry mass of the biomass nanomaterial. [Effects of the Invention]

[0014] According to the method of the present invention, a method for producing a highly dyed colorant derived from a biomass nanomaterial can be provided. [Brief explanation of the drawings]

[0015] [Figure 1] 1 shows ultraviolet-visible light absorption spectra of 0.01 wt % dispersions of dyed cellulose nanofibers obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0016] The presently disclosed method for producing a colorant includes mercerizing a biomass nanomaterial and mixing the mercerized biomass nanomaterial with a dye to dye the mercerized biomass nanomaterial, which results in a highly dyed colorant.

[0017] Hereinafter, embodiments for carrying out the present disclosure will be described in detail, but the scope of the present disclosure is not limited to these embodiments.

[0018] Biomass Nanomaterials Biomass nanomaterials are obtained by reducing naturally occurring materials such as animals and plants to the nanoscale (1 nm to 1000 nm). Biomass nanomaterials are available as powders or dispersions in water or organic solvents. Biomass nanomaterials may be in the form of a dispersion or an aqueous dispersion, as they are easy to handle.

[0019] The biomass nanomaterial includes, for example, at least one selected from the group consisting of cellulose nanofibers, cellulose nanocrystals, chitosan nanofibers, chitin nanofibers, and silk nanofibers. The biomass nanomaterial may be a derivative of any of the above. The biomass nanomaterial may be at least one selected from the group consisting of cellulose nanofibers, cellulose nanocrystals, chitosan nanofibers, and chitin nanofibers, or may be a cellulose nanofiber.

[0020] A nanomaterial is a material that has nanoscale external dimensions or nanoscale internal or surface structure. A nanofiber is a material that has two of its three external dimensions at the nanoscale and one significantly longer external dimension. The aspect ratio of a nanofiber can be, for example, 100 or greater. A nanocrystal is a nanomaterial that has a crystalline structure.

[0021] At least one external dimension (average) of the nanomaterial may be, for example, 1 nm to 500 nm. The external dimension may be 2 nm or more, or 3 nm or more. The external dimension may be 300 nm or less, or 200 nm or less.

[0022] The nanomaterial may have an outer dimension (average fiber diameter) of, for example, 1 nm to 500 nm. The nanofiber may have an outer dimension (average fiber length) of, for example, 0.1 to 200 μm. The nanofiber may have an aspect ratio (average fiber length / average fiber width) of, for example, 10 to 2,000.

[0023] The external dimensions may be catalog values. The external dimensions may also be calculated by measuring the external dimensions of a sufficient number of nanomaterials (e.g., 50 or more) using an atomic force microscope (AFM) or a transmission electron microscope (TEM) and averaging these measurements.

[0024] Cellulose nanofibers (CNFs) can be obtained by defibrating cellulose fibers contained in plants (typically pulp) to the nano-size level, or they can be produced by bacteria. Cellulose nanofibers produced by bacteria are called bacterial cellulose nanofibers.

[0025] Plant-derived CNFs are broadly classified into, for example, mechanically defibrated cellulose nanofibers and chemically defibrated cellulose nanofibers depending on the defibration method. The raw material for CNFs is not particularly limited. Examples of raw materials for CNFs include pulp contained in wood, bamboo, hemp, jute, kenaf, cotton, beet, agricultural waste, and cloth.

[0026] CNF is a cellulose microfibril (single nanofiber) consisting of crystalline, quasi-crystalline, and amorphous parts, or an aggregate of these in a longitudinally torn, tangled, or mesh-like structure. CNF also includes what is called cellulose nanofibril and fibrillated cellulose.

[0027] Mechanically defibrated cellulose nanofibers are obtained by defibrating pulp through mechanical grinding or beating. Specifically, mechanically defibrated cellulose nanofibers are obtained by introducing an aqueous suspension or slurry of pulp into, for example, a refiner, a high-pressure homogenizer, a grinder, a single-screw or multi-screw kneader, or a bead mill. Two or more of the above defibration methods can be combined as necessary.

[0028] An example of a commercially available mechanically defibrated cellulose nanofiber is BiNFI-s (registered trademark) manufactured by Sugino Machine Ltd.

[0029] Chemically defibrated cellulose nanofibers can be obtained by subjecting pulp to a treatment involving a chemical reaction, such as oxidation treatment, phosphate esterification treatment, sulfate esterification treatment, xanthate treatment, enzyme treatment, or ozone treatment.

[0030] Commercially available chemically defibrated cellulose nanofibers include, for example, Leocrysta (registered trademark) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., S-CNF (registered trademark) manufactured by Yokogawa Biofrontier Corporation, and RCNF (registered trademark) manufactured by Rengo Co., Ltd.

[0031] Bacterial cellulose can be obtained by culturing cellulose-producing bacteria, such as subspecies of acetic acid bacteria, in an appropriate medium under aeration and agitation, and then isolating and recovering the cellulose fibers produced outside the cells.

[0032] An example of a commercially available bacterial cellulose product is Fibnano (registered trademark) manufactured by Kusano Sakuko Co., Ltd.

[0033] Cellulose nanocrystals are obtained by removing the amorphous parts of cellulose through acid hydrolysis, and have a high degree of crystallinity.

[0034] Commercially available cellulose nanocrystals include CelluForce NCC manufactured by CelluForce. TM, CNC-Slurry-DS manufactured by Cellulose Lab TM Examples include:

[0035] mercerization Mercerization refers to the process of bringing a target object into contact with an alkaline solution to cause it to swell. Mercerizing biomass nanomaterials (hereinafter sometimes simply referred to as nanomaterials) changes their crystalline structure, causing them to crystallize with functional groups (OH groups in the case of CNF, chitosan nanofibers, and chitin nanofibers) oriented on the outer surface.

[0036] Crystallization of the nanomaterial reduces the viscosity of the resulting dispersion of mercerized nanomaterial. This improves the stirring efficiency of the dye bath in the subsequent dyeing process. Furthermore, the orientation of functional groups on the outer surface facilitates chemical bonding between the nanomaterial and dye, or the dye is more easily adsorbed onto the nanomaterial. As a result, more pigments (chromophores) are bound or adsorbed to the nanomaterial, resulting in a highly dyed colorant.

[0037] Mercerization is carried out by contacting the nanomaterial with a mercerizing agent in an aqueous solvent. Specifically, mercerization is carried out as follows: The nanomaterial and the aqueous solvent are mixed in a reaction vessel to prepare a dispersion. The obtained dispersion is adjusted to 5 to 100°C. The liquid temperature may be 10°C or higher, or 15°C or higher. The liquid temperature may be 80°C or lower, or 60°C or lower.

[0038] Next, a mercerizing agent (or an aqueous solution thereof) is added to the dispersion and stirred for 1 minute to 10 hours. The stirring time may be 5 minutes or more, or may be 10 minutes or more. The stirring time may be 5 hours or less, or may be 2 hours or less.

[0039] The amount of the mercerizing agent used is not particularly limited. The mercerizing agent may be added so that the pH of the dispersion becomes 11 or higher. When the pH is 11 or higher, the mercerization reaction proceeds easily. The pH of the dispersion may be 12 or higher, 13 or higher, or 14 or higher. There is no particular upper limit to the pH of the dispersion.

[0040] The aqueous solvent may be water (typically ion-exchanged water), a hydrophilic organic solvent, or a mixture thereof. Examples of hydrophilic organic solvents include alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutanol, and tert-butanol; and ketones such as acetone, diethyl ketone, and methyl ethyl ketone. These may be used alone or in combination of two or more.

[0041] In the mixed solvent, the amount of the hydrophilic organic solvent may be less than 20% by mass, or may be less than 10% by mass.

[0042] The nanomaterial is dispersed in the aqueous solvent. The concentration of the nanomaterial is not particularly limited as long as stirring is possible. The concentration of the nanomaterial may be, for example, 0.5 to 10% by mass. The concentration of the nanomaterial may be 1% by mass or more. The concentration of the nanomaterial may be 5% by mass or less.

[0043] Examples of the mercerizing agent include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. These may be used alone or in combination of two or more.

[0044] The mercerizing agent may be added to the aqueous solvent as a solid or as an aqueous solution. The concentration of the aqueous mercerizing agent solution is not particularly limited and may be, for example, 5 to 50% by mass. The concentration of the aqueous mercerizing agent solution may be 10% by mass or more. The concentration of the aqueous mercerizing agent solution may be 30% by mass or less.

[0045] The amount of mercerizing agent used may be 0.1 g or more and 40 g or less per 1 g (dry mass) of biomass nanomaterial. When the amount of mercerizing agent used is 0.1 g or more, the biomass nanomaterial is sufficiently alkali-swollen. When the amount of mercerizing agent used is 40 g or less, gelation of the biomass nanomaterial is suppressed, and dyeing efficiency can be improved. The amount of mercerizing agent used may be 0.2 g or more, or may be 0.5 g or more. The amount of mercerizing agent used may be 30 g or less, or may be 20 g or less.

[0046] The reaction vessel is not particularly limited as long as it is alkali-resistant. For example, a glass beaker, flask, or reaction kettle may be used. The stirring means is not particularly limited, and known devices such as a magnetic stirrer, stirring blade, or homogenizer may be used.

[0047] After mercerization and before dyeing, the nanomaterial may be neutralized. Acids used for neutralization include, for example, inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid; and organic acids such as formic acid, acetic acid, propionic acid, succinic acid, and p-toluenesulfonic acid. These acids may be used alone or in combination.

[0048] After mercerization (and further neutralization) and before dyeing, the reaction solution may be filtered, and the filtered residue (wet cake) containing the nanomaterial may be washed with water.

[0049] Dyeing process The mercerized nanomaterial is mixed with a dye to dye the nanomaterial. Mercerized nanomaterials are crystallized with their functional groups oriented on the outer surface, making them easily dyeable.

[0050] The dye may be added to the reaction solution obtained in the mercerization step or to the solution after neutralization. Alternatively, the reaction solution may be filtered, and an aqueous solvent may be added to the wet cake, to which the dye may be added.

[0051] The dye is not limited as long as it can dye the nanomaterial, and examples of the dye include at least one selected from the group consisting of reactive dyes, vat dyes, direct dyes, acid dyes, basic dyes, and fluorescent dyes.

[0052] Examples of reactive dyes include: CI Reactive Yellow 2,3,15,18,37,39,42,76,81,84,85,95,99,102,145, CI Reactive Orange 5,9,12,13,16,35,45,72,99, CI Reactive Red 1,3,4,13,15,21,24,31,33,112,114,116,120,125,151,195,206,218,226,245, CI Reactive Violet 1,24 CI Reactive Blue 2,5,10,13,14,15,15:1,19,21,49,50,63,69,71,72,75,162,176, CI Reactive Green 5, 8, 19 CI Reactive Brown 2,8,9,11,17,33, CI Reactive Black 1,5,8,23,39, Examples include:

[0053] Commercially available reactive dyes include Kayacion CF, Kayacion E, Kayacion E-CM, Kayacion E-LM, Kayacion A, Kayacion P, and Kayacion Pliquid (all manufactured by Nippon Kayaku Co., Ltd.).

[0054] Examples of vat dyes include: CI Vat Yellow 1,2,3,9,10,13,18,11,11:1,20,23,27,29,31,38,46,49, CI Vat Orange 1,2,4,9,11,15,16,17,18,19,20,23,26, CI Vat Red 1,5,6,10,13,20,21,23,26,28,29,33,37,38,40,41,42,48, CI Vat Violet 1:1,2,3,4,10,13,17,19,31, CI Vat Blue 1,3,4,5,6,7,8,10,11,13,25,30,32,33,34,35,36,37,41,48,48,66, CI Vat Green 1,2,3,4,5,13,14,17, CI Vat Brown 1,3,5,9,21,23,24,25,26,31,34,37,45,68,72, CI Vat Black 1,8,9,19,25,27,28,29,35, Examples include:

[0055] Commercially available vat dyes include Mikethrene and MitsuiVat (both manufactured by DyStar), and Cibanone (manufactured by Huntsman).

[0056] Direct dyes include, for example: CI Direct Yellow 11,12,50,86,87,130,132, CI Direct Orange 17,26,29,39,102,118:1, CI Direct Red 2,4,6,9,17,23,26,28,31,39,54,55,57,62,63,64,65,68,72,75,76,79,80,81,83,83:1,84,89,92,95,99,11 1,141,173,180,184,207,211,212,214,218,221,223,224,225,226,227,232,233,239,240,241,242,243,247, CI Direct Violet 7,9,35,47,48,51,66,90,93,94,95,98,100,101, CI Direct Blue 1,15,22,25,41,62,71,76,77,80,86,87,90,98,106,108,120,158,163,168,199,200,201,202,236,237,264, CI Direct Green 1,6,26,59,59, CI Direct Brown 2,95,116,161,210,223, CI Direct Black 17,19,22,31,32,38,51,62,71,74,112,113,154,168,195, Examples include:

[0057] Examples of acid dyes include: CI Acid Yellow 3,17,23,25,36,42,49,59,79,116,117,219, CI Acid Orange 5,7,10,24,33,67,94,156, CI Acid red 1,13,14,18,27,33,48,50,51,52,71,80,87,88,92,94,97,106,114,117,119,122,131,138,151,249,260,289,337,361, CI Acid Violet 7,17,54,68,90, CI Acid Blue 9,45,47,62,80,83,90,113,119,120,127:1,129,168,171,193,204,221,249,264,280 CI Acid Green 1,25,27,41,50,73,81, CI Acid Brown 14,75,98,116,163,165,349,358, CI Acid Black 2,26,52,52:1,63,107,155,172, Examples include:

[0058] Examples of basic dyes include: CI Basic Yellow 1,2,21,24,28,29,40,49,51,87,96, CI Basic Orange 14,22, CI Basic Red 1,2,9,12,14,15,18,22,46,49,54, CI Basic Violet 1,3,4,10,11,14,24, CI Basic Blue 3,7,9,11,17,26,41,47,53,54,57,62,162, CI Basic Green 1,4,5,18, CI Basic Brown 1,4, Examples include:

[0059] Examples of fluorescent dyes include: CI Fluorescent Brightener 28,52,87,113,134,135,166, Examples include:

[0060] In view of the fastness of the dyed product, the dye may be a reactive dye or a vat dye. In view of the vividness of the color of the dyed product and the abundance of color options, the dye may be a reactive dye.

[0061] The amount of dye used is, for example, 2% owf to 200% owf. When the amount of dye used is 2% owf or more, the nanomaterial can be easily dyed a deep color. When the amount of dye used is 200% owf or less, the nanomaterial can be dyed a sufficiently deep color. The amount of dye used may be 20% owf or more, or may be 50% owf or more. The amount of dye used may be 180% owf or less, or may be 150% owf or less. The amount of dye used (owf%) is expressed as the mass ratio of the dye to the dry mass of the nanomaterial.

[0062] A dyeing assistant may be used together with the dye. Examples of the dyeing assistant include neutral salts and basic salts. Examples of neutral salts include sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, and sodium nitrate. Examples of basic salts include inorganic salts such as sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide; and metal salts of organic acids such as sodium acetate, potassium acetate, sodium succinate, and potassium succinate. These may be used alone or in combination of two or more. If neutralization is performed after mercerization, the neutral salt need not be added.

[0063] The amount of dyeing assistant used is, for example, 10 g / L to 200 g / L per 1 L of dye solution. If the amount of dyeing assistant used is 10 g / L or more, it becomes easier to dye the nanomaterial in a darker color. If the amount of dyeing assistant used is 200 g / L or less, the nanomaterial can be dyed in a sufficiently dark color. The amount of dyeing assistant used may be 30 g / L or more, or may be 50 g / L or more. The amount of dyeing assistant used may be 180 g / L or less, or may be 150 g / L or less.

[0064] The aqueous solvents used in dyeing include the same aqueous solvents as those listed as being usable in mercerization.

[0065] The liquor ratio may be, for example, 1:15 to 1:500. When the liquor ratio is 1:15 or more, the viscosity can be easily adjusted to a level suitable for stirring. When the liquor ratio is 1:500 or less, the nanomaterial can be easily dyed in a deep color. The liquor ratio may be 1:30 or more, or 1:50 or more. The liquor ratio may be 1:300 or less, or 1:200 or less. The liquor ratio represents (mass of nanomaterial):(mass of dye liquor). The dye liquor contains at least a dye and an aqueous solvent.

[0066] The temperature of the dye liquor is, for example, 20 to 100° C. The temperature of the dye liquor may be 30° C. or higher, or 50° C. or higher. The temperature of the dye liquor may be 90° C. or lower, or 80° C. or lower.

[0067] After mixing the nanomaterial and the dye, the resulting mixture is stirred, for example, for 10 minutes to 10 hours. The stirring time may be 20 minutes or more, or 30 minutes or more. The stirring time may be 5 hours or less, or 2 hours or less.

[0068] The vessels and stirring means used in dyeing include the same vessels and stirring means as those usable in mercerization. Conventionally known dyeing machines for dyeing fabrics and fibers may also be used.

[0069] Other ingredients may be added to the dye liquor. Examples of other ingredients include thickeners, reduction inhibitors, hydrotropic agents, retarders, penetrating agents, and mordants. Examples of thickeners include starches, rubbers, sodium alginate, seaweed such as funori (seaweed), modified starches, modified rubbers, celluloses such as methyl cellulose and carboxymethyl cellulose, and synthetic thickeners such as polyvinyl alcohol. Among these, sodium alginate may be added. Examples of reduction inhibitors include sodium 3-nitrobenzenesulfonate. Examples of hydrotropic agents include ureas.

[0070] Examples of retarders include nonionic surfactants such as amylazine, Noigen, and Leopol; and anionic surfactants. Examples of penetrants include anionic surfactants such as sodium alkyl sulfosuccinate, sulfates of branched alcohols, and phosphates of short-chain alcohols; and nonionic surfactants such as EO adducts of branched alcohols. Examples of mordants include water-soluble metal salts (water-soluble metal salts) such as iron(III) chloride, iron(III) nitrate, copper sulfate, copper acetate, tin(II) chloride, potassium aluminum sulfate, aluminum acetate, aluminum chloride, magnesium sulfate, and magnesium chloride. These may be used alone or in combination. The hydrotropic agent may be used in combination with a thickener, a dyeing assistant, or a reduction inhibitor.

[0071] The amount of the other components used is not particularly limited and is set appropriately depending on the purpose, and is, for example, 0.001 to 100 parts by mass per 1 part by mass of the nanomaterial.

[0072] After dyeing, filtration and washing with water may be carried out. The filtration method is not particularly limited, and a conventionally known method can be used. Examples of the filtration method include vacuum filtration, pressure filtration, and hot filtration. Filtration and washing with water are carried out, for example, until the conductivity of the filtrate is 1 mS / cm or less. The conductivity of the filtrate may be 500 μS / cm or less, or may be 200 μS / cm or less. A surfactant may be used during washing with water.

[0073] color material The colorant obtained by the method of the present disclosure has a larger amount of dyes (chromophores) bound or adsorbed thereto. The colorant is dyed to a deep color. The colorant can be used in the same manner and for the same applications as conventional pigments or dyes. The colorant can be blended into, for example, inks (typically, writing inks, inkjet recording inks, and printing inks), paints, resins, and toners. Inks containing the colorant can develop a color on a recording medium with a density that is sufficiently visible.

[0074] The coloring material can be dispersed in an aqueous medium at a concentration of, for example, 5 to 10% by mass, and even in such a highly concentrated dispersion, the dispersibility and dispersion stability are high.

[0075] In aqueous writing inks, the concentration of the colorant may be, for example, 1 to 5% by mass. In inkjet recording inks, the concentration of the colorant may be, for example, 1 to 3% by mass. Water-based writing inks are used in, for example, ballpoint pens or felt-tip pens. Various inks may contain, for example, preservatives and surfactants.

[0076] The coloring material may be used alone or in combination with a plurality of different colors. The coloring materials obtained by the method of the present disclosure can express a variety of hues. [Example]

[0077] Next, the present disclosure will be described more specifically with reference to examples, but the present disclosure is not limited to these examples.

[0078] [Example 1] Mercerization process 12.0 g of mechanically defibrated cellulose nanofibers (BiNFi-s Ultrashort, manufactured by Sugino Machine, solids concentration 5.0 wt%, average fiber diameter 10-50 nm) and 16.0 g of ion-exchanged water were placed in a 100 mL beaker and stirred with a magnetic stirrer. 22.5 g of 20% aqueous sodium hydroxide solution was then added to the beaker and stirred for 30 minutes. After stirring, the mixture was neutralized with 12.1 g of concentrated hydrochloric acid to obtain a mercerized cellulose nanofiber dispersion.

[0079] Dyeing process 0.60 g (100% owf) of red reactive dye (CI Reactive Red 195) was added to the mercerized cellulose nanofiber dispersion, and the mixture was heated to 60°C in a water bath over 20 minutes while stirring with a magnetic stirrer. After the temperature was raised, 9.0 g (150 g / L) of sodium carbonate was added and stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0080] [Comparative Example 1] 8.0 g of mechanically defibrated cellulose nanofibers were placed in a 100 mL beaker and diluted with ion-exchanged water to a total volume of 40.0 g. Subsequently, while stirring at 5,000 rpm using a homogenizer, 6.0 g of Glauber's salt (150 g / L) was added and dissolved. This was further stirred at 8,400 rpm for 10 minutes.

[0081] Next, 0.40 g of red reactive dye (100% owf) was added, and the mixture was heated to 60°C in a water bath over 20 minutes while stirring with a magnetic stirrer. After the temperature was raised, 4.0 g of sodium carbonate (100 g / L) was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0082] [Example 2] Mercerization process 20.2 g of mechanically defibrated cellulose nanofibers and 24.3 g of ion-exchanged water were placed in a 300 mL beaker and stirred with a magnetic stirrer. 36.4 g of 20% aqueous sodium hydroxide solution was then added to the beaker and stirred for 30 minutes. After stirring, the mixture was neutralized with 19.7 g of concentrated hydrochloric acid to obtain a mercerized cellulose nanofiber dispersion.

[0083] Dyeing process 1.00 g (100% owf) of a yellow reactive dye (CI Reactive Yellow 145) was added to the mercerized cellulose nanofiber dispersion, and the mixture was heated to 80°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After the temperature was raised, 15.1 g (150 g / L) of sodium carbonate was added and stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0084] Comparative Example 2 20.2 g of mechanically defibrated cellulose nanofibers were placed in a 300 mL beaker and diluted with ion-exchanged water to a total volume of 100 g. Subsequently, 15.0 g of Glauber's salt (150 g / L) was added and dissolved while stirring at 5,000 rpm using a homogenizer. This was further stirred at 8,400 rpm for 5 minutes.

[0085] Next, 1.00 g of yellow reactive dye (100% owf) was added, and the mixture was heated to 80°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After the temperature was raised, 15.0 g of sodium carbonate (150 g / L) was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0086] [Example 3] Mercerization process 40.0 g of mechanically defibrated cellulose nanofibers and 48.9 g of ion-exchanged water were placed in a 300 mL beaker and stirred with a magnetic stirrer. 72.7 g of 20% aqueous sodium hydroxide solution was then added to the beaker and stirred for 30 minutes. After stirring, the mixture was neutralized with 40.0 g of concentrated hydrochloric acid to obtain a mercerized cellulose nanofiber dispersion.

[0087] Dyeing process 2.00 g (100% owf) of blue reactive dye (CI Reactive Blue 21) was added to the mercerized cellulose nanofiber dispersion, and the mixture was heated to 70°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After the temperature was raised, 30.0 g (150 g / L) of sodium carbonate was added and stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0088] Comparative Example 3 70.0 g of mechanically defibrated cellulose nanofibers were placed in a 500 mL beaker and diluted with ion-exchanged water to a total volume of 350 g. Subsequently, 52.5 g of Glauber's salt (150 g / L) was added and dissolved while stirring at 8400 rpm using a homogenizer. This was further stirred at 8400 rpm for 10 minutes.

[0089] Next, 3.50 g (100% owf) of blue reactive dye was added, and while stirring with a magnetic stirrer, the temperature was raised to 70°C in a water bath over 30 minutes. After the temperature was raised, 35.0 g (100 g / L) of sodium carbonate was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0090] [Example 4] Mercerization process In the same manner as in Example 2, a mercerized cellulose nanofiber dispersion was obtained.

[0091] Dyeing process 1.0 g (100% owf) of black reactive dye (CI Reactive Black 5) was added to the mercerized cellulose nanofiber dispersion, and the mixture was heated to 50°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After the temperature was raised, 15.1 g (150 g / L) of sodium carbonate was added and stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0092] Comparative Example 4 10.0 g of mechanically defibrated cellulose nanofibers were placed in a 100 mL beaker and diluted with ion-exchanged water to a total volume of 50.3 g. Subsequently, 7.5 g of Glauber's salt (150 g / L) was added and dissolved while stirring at 8400 rpm using a homogenizer. This was further stirred at 8400 rpm for 10 minutes.

[0093] Next, 0.50 g of black reactive dye (100% owf) was added, and while stirring with a magnetic stirrer, the temperature was raised to 50°C in a water bath over 30 minutes. After the temperature was raised, 5.00 g of sodium carbonate (100 g / L) was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0094] [Example 5] Mercerization process 50.3 g of bamboo cellulose nanofiber (nanoforest-S, manufactured by Chuetsu Pulp Industries Co., Ltd., solids concentration 1.3 wt%) was weighed into a 100 mL beaker and filtered through filter paper. The resulting wet cake was placed in a 200 mL beaker, and 22.5 g of 20% aqueous sodium hydroxide solution was added. Ion-exchanged water was then added until the total volume reached 50.0 g. This was stirred with a magnetic stirrer for 30 minutes. Subsequently, the mixture was neutralized with 12.3 g of concentrated hydrochloric acid to obtain a mercerized cellulose nanofiber dispersion.

[0095] Dyeing process 0.60 g (100% owf) of red reactive dye (CI Reactive Red 195) was added to the mercerized cellulose nanofiber dispersion, and the mixture was heated to 60°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After heating, 9.9 g (150 g / L) of sodium carbonate was added and stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0096] Comparative Example 5 38.6 g of bamboo cellulose nanofiber (solid content 1.3 wt%) was placed in a 100 mL beaker and diluted with ion-exchanged water to a total volume of 50.0 g. Then, while stirring at 8,400 rpm using a homogenizer, 7.50 g of Glauber's salt (150 g / L) was added and dissolved. This was further stirred at 10,000 rpm for 10 minutes.

[0097] Next, 0.50 g of red reactive dye (100% owf) was added, and while stirring with a magnetic stirrer, the temperature was raised to 60°C in a water bath over 30 minutes. After the temperature was raised, 5.0 g of sodium carbonate (100 g / L) was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0098] [Example 6] Mercerization process 67.2 g of chemically defibrated cellulose nanofiber (RCNF, manufactured by Rengo Co., Ltd., solids concentration 1.49 wt%, fiber diameter 3-10 nm) and 54.9 g of 20% aqueous sodium hydroxide solution were placed in a 300 mL beaker. After stirring with a magnetic stirrer for 30 minutes, the mixture was neutralized with 29.6 g of concentrated hydrochloric acid to obtain a mercerized cellulose nanofiber dispersion.

[0099] Dyeing process 1.00 g (100% owf) of red reactive dye (CI Reactive Red 195) was added to the mercerized cellulose nanofiber dispersion, and the mixture was heated to 60°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After the temperature was raised, 22.7 g (150 g / L) of sodium carbonate was added and stirred for 90 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0100] Comparative Example 6 55.0 g of chemically defibrated cellulose nanofibers were placed in a 200 mL beaker and diluted with ion-exchanged water to a total volume of 60.2 g. Then, 9.0 g of Glauber's salt (150 g / L) was added and dissolved while stirring at 8,400 rpm using a homogenizer.

[0101] Next, 0.60 g of red reactive dye (100% owf) was added, and the mixture was heated to 60°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After the temperature was raised, 9.0 g of sodium carbonate (150 g / L) was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0102] [Example 7] Mercerization process 26.7 g of cellulose nanocrystals (CNC-Slurry-DS, manufactured by Cellulose Lab, solids concentration 3.74 wt%), 17.7 g of ion-exchanged water, and 36.3 g of 20% aqueous sodium hydroxide solution were placed in a 200 mL beaker and stirred for 30 minutes with a magnetic stirrer. After stirring, the mixture was neutralized with 19.9 g of concentrated hydrochloric acid to obtain a mercerized cellulose nanocrystal dispersion.

[0103] Dyeing process 1.00 g (100% owf) of black reactive dye (CI Reactive Black 5) was added to the mercerized cellulose nanocrystal dispersion, and the mixture was heated to 50°C in a water bath over 30 minutes while stirring with a magnetic stirrer. After heating, 15.0 g (150 g / L) of sodium carbonate was added and stirred for 90 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0104] Comparative Example 7 A 100 mL beaker was charged with 13.4 g of cellulose nanocrystals and 36.9 g of ion-exchanged water. While stirring with a magnetic stirrer, 0.50 g (100% owf) of black reactive dye (CI Reactive Black 5) and 5.0 g (100 g / L) of sodium sulfate were added. The mixture was then heated to 50°C over 30 minutes in a water bath while stirring with a magnetic stirrer. After heating, 7.5 g (150 g / L) of sodium carbonate was added and stirred for 90 minutes to dye the cellulose nanocrystals. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (coloring material).

[0105] [Comparative Example 8] 21.2 g of mechanically defibrated cellulose nanofibers (BiNFi-s Ultrashort, manufactured by Sugino Machine, solids concentration 5.0 wt%) was placed in a 200 mL beaker and diluted with ion-exchanged water to a total volume of 105.2 g. Subsequently, while stirring at 5000 rpm using a homogenizer, 15.8 g of Glauber's salt (150 g / L) was added and dissolved. This was further stirred at 8400 rpm for 10 minutes.

[0106] Next, 2.11 g (200% owf) of red reactive dye was added, and while stirring with a magnetic stirrer, the temperature was raised to 60°C in a water bath over 30 minutes. After the temperature was raised, 10.5 g (100 g / L) of sodium carbonate was added, and the mixture was stirred for 60 minutes to dye the cellulose nanofibers. After dyeing, the mixture was filtered while hot and washed with ion-exchanged water. Filtration and washing were repeated until the color of the filtrate became lighter and the electrical conductivity reached 200 μS / cm or less. This resulted in a wet cake of dyed cellulose nanofiber (colorant).

[0107] [evaluation] Absorbance measurement The wet cake was dispersed in ion-exchanged water to a solids concentration of 0.01 wt%. The resulting dispersion was placed in a quartz cell (light path length 1 cm), and the ultraviolet-visible light absorption spectrum was measured using an absorbance meter (UV-2600i, manufactured by Shimadzu Corporation). The maximum absorption wavelength and the absorbance measurement results are shown in Tables 1 and 2. The higher the absorbance, the better the color development.

[0108] Color development test The wet cake was dispersed in ion-exchanged water to a solids concentration of 2 wt%. 0.2 g of the resulting dispersion was dropped onto superfine paper using a dropper. The dispersion was then spread at a constant speed using a No. 6 bar coater (approximate film thickness: 12 μm) and dried to obtain a sample. The sample of Comparative Example 2 was assigned an evaluation of B (coloration was evident, albeit somewhat light), and the color intensity of the other samples was visually evaluated in comparison. The evaluation criteria were as follows. The results are shown in Tables 1 and 2.

[0109] (Evaluation criteria) A: The coloring is clearly visible. B: Although it is slightly light, it can be seen that it is colored. C: Almost no coloring can be seen

[0110] [Table 1]

[0111] [Table 2]

[0112] As shown in Tables 1 and 2, the coloring materials of the Examples that had undergone mercerization exhibited higher absorbance than the coloring materials of the Comparative Examples, indicating that they were dyed deeply. It was also confirmed that the coloring materials of the Examples developed a deep color when applied to paper.

[0113] The coloring materials obtained in Examples 1 to 4 exhibit magenta, yellow, cyan, or black hues, respectively, and can be adjusted to any desired hue by appropriately mixing these coloring materials.

[0114] In Comparative Example 8, the nanomaterial was dyed using twice the reactive dye, but it was not possible to dye it darker than the coloring material of Example 1 that had undergone mercerization. [Industrial Applicability]

[0115] As described above, the colorant obtained by the method of the present disclosure has a darker color than conventional dyed cellulose nanofibers, and can therefore be suitably used for coloring inks for writing instruments, inks for inkjet recording, printing inks, paints, resins, etc.

Claims

1. Mercerizing the biomass nanomaterial; and mixing the mercerized biomass nanomaterial with a dye to dye the mercerized biomass nanomaterial.

2. The method for producing a colorant according to claim 1, wherein the biomass nanomaterial comprises at least one selected from the group consisting of cellulose nanofibers, cellulose nanocrystals, chitosan nanofibers, chitin nanofibers, and silk nanofibers.

3. The method for producing a colorant according to claim 2 , wherein the cellulose nanofibers include at least one selected from the group consisting of mechanically defibrated cellulose nanofibers, chemically defibrated cellulose nanofibers, and bacterial cellulose nanofibers.

4. 2. The method for producing a colorant according to claim 1, wherein the dye comprises at least one dye selected from the group consisting of reactive dyes, vat dyes, direct dyes, acid dyes, basic dyes, and fluorescent dyes.

5. The mercerization is carried out by contacting the biomass nanomaterial with a mercerizing agent in an aqueous solvent; The method for producing a color material according to claim 1 , wherein the amount of the mercerizing agent used is 0.1 g or more and 40 g or less per 1 g of the dry mass of the biomass nanomaterial.

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