Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/023—Emulsion inks
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D11/00—Inks
  • C09D11/02—Printing inks
  • C09D11/08—Printing inks based on natural resins

Definitions

• the present invention relates to a water-based ink composition, a method for producing the same, and a recording method.
• water-based ink compositions (hereinafter sometimes referred to as "water-based ink”) have replaced organic solvent-based inks in a wide range of fields. In addition to being able to reduce the safety and environmental load, this is for the purpose of avoiding contamination of food and the like with organic solvents derived from the ink composition in the ink lamination application for flexible packaging. This is because there is a demand for water-based inks with reduced odor as inks that can be used even in closed spaces.
• Nanocellulose is cellulose that has been uniformly refined at the nano level (nanofibers), and is known to be added to pigment compositions for the purpose of imparting good rheological properties (e.g., See Patent Document 1).
• a water-based ink composition is known that ensures excellent dispersion stability even with a coloring agent having a high specific gravity by incorporating nanocellulose into the water-based ink (see, for example, Patent Document 2).
• the cellulose fibers contained in the aqueous ink composition of Patent Document 2 are cellulose fibers having a number average fiber diameter of 2 to 150 nm, the cellulose has a cellulose I-type crystal structure, and each glucose unit in the cellulose molecule
• the hydroxyl group at the C6 position of is selectively oxidatively modified to become either an aldehyde group, a ketone group, or a carboxy group, and the content of the carboxy group is 0.6 to 2.0 mmol/g, as measured by the semicarbazide method.
• the total content of aldehyde groups and ketone groups is 0.3 mmol/g or less.
• the water-based ink composition of Patent Document 2 is said to have excellent long-term dispersion stability.
• Patent Document 3 discloses an aqueous polymer comprising at least a pigment, an anionic group-containing organic polymer compound, and bio-nanofibers having an average diameter of 1 nm or more and 100 nm or less and an aspect ratio of 100 or more. Pigment dispersions are disclosed. The aqueous pigment dispersion of Patent Document 3 is said to be excellent in optical density, scratch resistance, and the like of the resulting image.
• microfibrillated cellulose used in the pigment-containing composition of Patent Document 1 is produced by enzymatically treating cellulosic fibers. Since an enzyme is used, there is a problem in efficiently and stably supplying microfibrillated cellulose.
• the cellulose fibers contained in the water-based ink composition of Patent Document 2 are obtained by oxidation using a co-oxidizing agent in the presence of an N-oxyl compound such as TEMPO. And those obtained through refinement processing are used.
• the cellulose fibers thus obtained have a low production efficiency, and there is a problem that an aqueous ink composition using them cannot be efficiently obtained.
• the bio-nanofiber contained in the aqueous pigment dispersion of Patent Document 3 is specifically nanocellulose obtained by mechanical fibrillation, and energy is required for the production of nanocellulose, so the aqueous ink composition can be obtained efficiently. I have a problem that I can't
• the ink composition is required to have functionality such as robustness, adhesion, and optical density of the coating film obtained from the composition.
• the present invention has been made in view of the above circumstances, and the main object thereof is to provide a water-based ink composition that can achieve both the fastness, adhesion, and optical density of a coating film, and an efficient method for producing the same.
• the present invention provides the following means.
• An aqueous ink composition comprising nanocellulose, the nanocellulose contains an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof and is substantially free of N-oxyl compounds; Aqueous ink composition. [2] further comprising an anionic group-containing organic polymer compound, The water-based ink composition according to [1]. [3] At least part of the carboxy groups of the nanocellulose are modified with at least one selected from the group consisting of metals, ammonia, amines and quaternary ammoniums. The water-based ink composition according to [1] or [2]. [4] for inkjet recording, The water-based ink composition according to any one of [1] to [3].
• a recording method comprising a step of ejecting the aqueous ink composition according to any one of [1] to [3] onto a recording member by an inkjet method.
• a method for producing an aqueous ink composition containing nanocellulose comprising: a step of stirring a mixture containing oxidized cellulose and a material other than nanocellulose of the aqueous ink composition to defibrate the oxidized cellulose to obtain an aqueous ink composition containing nanocellulose; the oxidized cellulose contains an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof and is substantially free of N-oxyl compounds; Production method.
• a method for producing an aqueous ink composition containing nanocellulose comprising: a step of stirring oxidized cellulose and continuously mixing materials other than nanocellulose of the aqueous ink composition to defibrate the oxidized cellulose to obtain an aqueous ink composition containing nanocellulose;
• the oxidized cellulose contains an oxide of a cellulosic raw material with hypochlorous acid or a salt thereof and is substantially free of N-oxyl compounds;
• the material further comprises an anionic group-containing organic polymer compound, The production method according to [6] or [7].
• At least part of the carboxyl groups of the oxidized cellulose are modified with at least one selected from the group consisting of metals, ammonia, amines and quaternary ammoniums.
• the present invention it is possible to provide a water-based ink composition capable of satisfying both the fastness, adhesion, and optical density of a coating film, and an efficient method for producing the same.
• the aqueous ink composition of the present invention contains nanocellulose.
• the nanocellulose contained in the water-based ink composition of the present invention contains an oxide of a cellulosic raw material (oxidized nanocellulose) by hypochlorous acid or a salt thereof, and does not substantially contain an N-oxyl compound.
• the water-based ink composition of the present invention has good color development (optical density) and scratch resistance of images formed from the water-based ink composition. The mechanism is presumed as follows, but is not limited. Since the glucose units that make up cellulose have a chair conformation, hydroxyl groups are coordinated horizontally with respect to the glucopyranose ring, and only C and H are aligned vertically.
• the pigment particles formed by nanocellulose and the composite with an anionic group-containing organic polymer compound described later have a We believe that we have achieved a high level of balance, which is essential for stable dispersion of pigments, by reducing the interfacial tension and controlling the charge on the surface of the pigment particles, while providing a repulsive force that can overcome the van der Waals forces between the pigment particles. . Therefore, the pigment particles can be immobilized without unnecessarily permeating into the printed material, thereby exhibiting a high optical density and preventing color mixing between adjacent color inks in multicolor color printing.
• the nanocellulose contained in the present invention is excellent in function as a binder, and is excellent in abrasion resistance such as toughness and adhesion of the coating film. Furthermore, the nanocellulose of the present invention can be obtained by easily defibrating oxidized cellulose oxidized with hypochlorous acid or a salt thereof. Nano cellulose can be efficiently obtained without requiring a large energy load by a high-pressure homogenizer or the like for nanoization. Therefore, the water-based ink composition of the invention can also be efficiently obtained.
• the nanocellulose in the present invention is nanoized oxidized cellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof.
• the oxidized cellulose can also be referred to as an oxide of a cellulosic raw material. Therefore, the nanocellulose in the present invention includes oxides of cellulosic raw materials by hypochlorous acid or salts thereof.
• the main component of plants is cellulose, and bundles of cellulose molecules are called cellulose microfibrils. Cellulose in cellulosic raw materials is also contained in the form of cellulose microfibrils.
• the nanocellulose in the present invention is a general term for nano-ized cellulose, and includes fine cellulose fibers, cellulose nanocrystals, and the like, as well as modified products thereof (details of modified products will be described later). Fine cellulose fibers are also referred to as cellulose nanofibers (also referred to as CNF).
• the water-based ink composition of the present invention contains nanocellulose, but it can also be produced by blending oxidized cellulose that has been defibrated and nanoized. can also be produced by nanoizing the oxidized cellulose during preparation. Therefore, the nanocellulose in the water-based ink composition has been nanoized at an appropriate time.
• N-oxyl compounds such as TEMPO are not used in the treatment of oxidizing cellulosic raw materials with hypochlorous acid or salts thereof. Therefore, the nanocellulose in the present invention is substantially free of N-oxyl compounds. Therefore, nanocellulose is highly safe because the impact of N-oxyl compounds on the environment and the human body is sufficiently reduced, so it can be applied to cosmetics, foods, medical products, and the like.
• the nanocellulose (or oxidized cellulose) "substantially does not contain N-oxyl compounds” means that the nanocellulose does not contain any N-oxyl compounds or means that the content of is 2.0 mass ppm or less, preferably 1.0 mass ppm or less, relative to the total amount of nanocellulose.
• the N-oxyl compound when the content of the N-oxyl compound is preferably 2.0 ppm by mass or less, more preferably 1.0 ppm by mass or less as an increase from the cellulosic raw material, "the N-oxyl compound is substantially means “not including”.
• the content of the N-oxyl compound can be measured by known means. Known means include a method using a trace total nitrogen analyzer (for example, manufactured by Nitto Seiko Analyticc Co., Ltd., device name: TN-2100H).
• the above oxidized cellulose has excellent fibrillating properties.
• the oxidized cellulose can be uniformly pulverized even when the defibration treatment is performed under mild conditions, and is excellent in easy fibrillation.
• the viscosity of the slurry is stable over time and the handling property is excellent.
• the carboxy group content of nanocellulose and oxidized cellulose is preferably 0.20 to 2.0 mmol/g.
• the amount of carboxyl groups is 0.20 mmol/g or more, the oxidized cellulose can be imparted with sufficient easy disentanglement properties. As a result, even when defibration is performed under mild conditions, a nanocellulose-containing slurry with uniform quality can be obtained, and the viscosity stability and handleability of the slurry can be improved.
• the amount of carboxyl groups is 2.0 mmol/g or less, excessive decomposition of cellulose can be suppressed during fibrillation treatment, and nanocellulose having a low proportion of particulate cellulose and uniform quality can be obtained. .
• the carboxy group content of nanocellulose and oxidized cellulose is more preferably 0.30 mmol/g or more, still more preferably 0.35 mmol/g or more, and even more preferably 0.40 mmol/g or more. , still more preferably 0.42 mmol/g or more, still more preferably 0.50 mmol/g or more, still more preferably over 0.50 mmol/g, still more preferably 0.55 mmol/g or more is.
• the upper limit of the amount of carboxyl groups may be less than 2.0 mmol/g, may be 1.5 mmol/g or less, may be 1.2 mmol/g or less, or may be 1.0 mmol/g or less. or 0.9 mmol/g or less.
• a preferable range of the amount of carboxyl groups can be determined by appropriately combining the above-mentioned upper limit and lower limit.
• the amount of carboxyl groups in nanocellulose is more preferably 0.30 mmol/g or more and less than 2.0 mmol/g, still more preferably 0.35 to 2.0 mmol/g, still more preferably 0.35 to 1 .5 mmol/g, still more preferably 0.40 to 1.5 mmol/g, even more preferably 0.50 to 1.2 mmol/g, even more preferably greater than 0.50 to 1.2 mmol /g, and even more preferably between 0.55 and 1.0 mmol/g.
• the amount of carboxyl groups was determined by adding 0.1M hydrochloric acid aqueous solution to an aqueous solution of oxidized cellulose and water to adjust the pH to 2.5, and then adding dropwise 0.05N sodium hydroxide aqueous solution to adjust the pH. is a value calculated from the amount (a) of sodium hydroxide consumed in the neutralization step of a weak acid in which the change in electrical conductivity is moderate, using the following formula. The details follow the method described in the examples below.
• the amount of carboxyl groups can be adjusted by changing the reaction time of the oxidation reaction, the reaction temperature, the pH of the reaction solution, and the like.
• Carboxy group weight a (ml) x 0.05/oxidized cellulose mass (g)
• the oxidized cellulose is obtained, for example, by oxidizing a cellulosic raw material under conditions in which the available chlorine concentration of hypochlorous acid or a salt thereof in the reaction system is relatively high (for example, 6% by mass to 43% by mass). Obtainable.
• the oxidized cellulose in the present invention can also be produced by appropriately controlling reaction conditions such as available chlorine concentration, pH during the reaction, and reaction temperature.
• the oxidized cellulose thus obtained preferably has a structure in which at least two of the hydroxyl groups of the glucopyranose rings constituting the cellulose are oxidized. It preferably has a structure in which the hydroxyl group at the 3-position is oxidized and a dicarboxy group is introduced.
• the hydroxyl group at the 6th position of the glucopyranose ring in the oxidized cellulose is not oxidized and remains as the hydroxyl group.
• the position of the carboxy group in the glucopyranose ring of oxidized cellulose can be analyzed by solid-state 13 C-NMR spectrum.
• Rayon has the same chemical structure as cellulose, and its oxide (rayon oxide) is water soluble.
• rayon oxide rayon oxide
• a carbon peak attributed to a carboxy group is observed at 165 to 185 ppm.
• two signals appear in this chemical shift range.
• solution two-dimensional NMR measurement it can be determined that the carboxy groups were introduced at the 2- and 3-positions.
• Solid 13 C-NMR of oxidized cellulose or nanocellulose obtained by oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof shows two signals at 165 to 185 ppm when the amount of carboxyl groups introduced is large. , a very broad signal may appear when the amount of carboxyl group introduced is small.
• the signals of the carboxyl carbon atoms introduced at the 2nd and 3rd positions are close to each other, and solid-state 13 C-NMR with low resolution cannot sufficiently separate the two signals. Therefore, when the amount of carboxyl group introduced is small, a broad signal is observed.
• the introduction of carboxyl groups at the 2nd and 3rd positions can be confirmed by evaluating the spread of peaks appearing at 165 to 185 ppm. That is, after drawing a baseline to the peaks in the range of 165 ppm to 185 ppm in the solid 13 C-NMR spectrum and obtaining the overall area value, the two peak area values obtained by vertically dividing the area value at the peak top. A ratio (large area value/small area value) is obtained, and if the ratio of the peak area values is 1.2 or more, it can be said that the peak is broad.
• the presence or absence of the broad peak can be determined by the ratio of the length L of the baseline in the range of 165 ppm to 185 ppm to the length L' of the perpendicular line from the top of the peak to the baseline. That is, if the ratio L'/L is 0.1 or more, it can be determined that a broad peak exists.
• the ratio L'/L may be 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more.
• the upper limit of the ratio L'/L is not particularly limited, it is usually 3.0 or less, may be 2.0 or less, or may be 1.0 or less.
• the structure of the glucopyranose ring can also be determined by analysis according to the method described in Sustainable Chem. Eng. 2020, 8, 48, 17800-17806.
• the nanocellulose in the present invention is an aggregate of single unit fibers.
• carboxylated nanocellulose it is sufficient that it contains at least one carboxylated nanocellulose, and carboxylated nanocellulose is preferably the main component.
• carboxylated nanocellulose is the main component, which means that the ratio of carboxylated nanocellulose to the total amount of nanocellulose is more than 50% by mass, preferably more than 70% by mass, more preferably 80% by mass. It refers to being in excess. Although the upper limit of the above ratio is 100% by mass, it may be 98% by mass or 95% by mass.
• the average fiber length of nanocellulose is preferably 50 to 2000 nm, more preferably 100 to 1000 nm, still more preferably 100 to 700 nm, still more preferably 100 to 500 nm, still more preferably 100 to 100 nm. 400 nm. If the average fiber length exceeds 2000 nm, the slurry will thicken significantly and become difficult to handle. Moreover, when the average fiber length is less than 50 nm, it becomes difficult to express the viscosity, which is a feature of CNF.
• the average fiber width of nanocellulose is preferably 1 to 200 nm, more preferably 1 to 15.0 nm, more preferably 1 to 10 nm, still more preferably 1 to 5 nm. If the average fiber width is less than 1 nm, it becomes difficult to improve the strength of the resin containing nanocellulose. Further, when the average fiber width is larger than 200 nm, the ejection stability in ink jet printing may be lowered when an ink composition is prepared.
• the average fiber width and average fiber length are obtained by mixing nanocellulose and water so that the concentration of nanocellulose is approximately 1 to 10 ppm, and naturally drying the sufficiently diluted cellulose aqueous dispersion on a mica base material.
• the image processing conditions are arbitrary, but there are cases where the values calculated for the same image differ depending on the conditions.
• the range of difference in values depending on the conditions is preferably within the range of ⁇ 100 nm for the average fiber length.
• the range of difference in values depending on conditions is preferably within the range of ⁇ 10 nm for the average fiber width.
• the nanocellulose in the present invention contains a carboxy group, but the carboxy group may be of H type (--COOH), or in a salt form (--COO - X + : X + is a cation that forms a salt form). It may be in a modified form by reacting the carboxyl group with another compound to form a covalent bond. Therefore, the water-based ink composition of the present invention encompasses embodiments containing nanocellulose in which at least part of the carboxy groups of nanocellulose are modified with metal, ammonia, amine or quaternary ammonium. A metal, ammonia, amine or quaternary ammonium may be added to the water-based ink composition of the present invention in the manufacturing process, if necessary.
• At least part of the carboxy groups of the nanocellulose are thereby modified with metals, ammonia, amines or quaternary ammoniums. Further, nanocellulose previously modified with metal, ammonia, amine or quaternary ammonium may be used in the production of the aqueous ink composition of the present invention.
• modified nanocellulose refers to the carboxy groups of nanocellulose forming interactions with metals, ammonia, amines, or quaternary ammonium.
• the interaction is not limited as long as it is a chemical bond that forms an interaction with a carboxy group, such as an ionic bond or a covalent bond.
• Metals, ammonia, amines, or quaternary ammonium salt compounds interact with carboxyl groups on the surface of nanocellulose to modify nanocellulose, resulting in components in aqueous ink compositions (for example, pigments and anionic group-containing organic pigments). (molecular compounds, etc.).
• nanocellulose modified with metals, ammonia, amines or quaternary ammonium salt compounds also functions as a surfactant. This makes it possible to omit the use of a surfactant in the step of dispersing the anionic group-containing organic polymer compound. Not using a surfactant is advantageous in terms of workability because no foaming occurs when the obtained water-based ink composition dries.
• the metal that modifies nanocellulose is not particularly limited, and examples thereof include sodium, potassium, magnesium, lithium, silver, gold, copper, zinc, etc. When used in water-based inkjet recording ink, it should be potassium salt. is preferable in terms of improving ejection stability.
• the amine that modifies nanocellulose is not particularly limited, and may be primary, secondary, or tertiary.
• the number of carbon atoms in the hydrocarbon or aromatic group bonded to the nitrogen atom of the amine or quaternary ammonium salt compound (if two or more hydrocarbon or aromatic groups are bonded to the nitrogen atom, the total The number of carbon atoms) is not particularly limited, and may be selected from 1 to 100 carbon atoms.
• the number of carbon atoms is preferably 3 or more, more preferably 5 or more, from the viewpoint of miscibility, which is the ease of compatibility with the resin component by imparting sufficient hydrophobicity to nanocellulose.
• a prolene oxide/ethylene oxide (PO/EO) copolymer part or the like can also be used. These may be introduced into nanocellulose singly or in combination of two or more. From the viewpoint of improving pigment dispersibility, amines having a PO/EO copolymer moiety are preferred.
• the amine having a PO/EO copolymer moiety can be prepared according to a known method, and JP-A-3-181448 and the like can be referred to for the production method.
• amines having a PO/EO copolymer moiety are also suitably used, and specific examples include Jeffamine M-600, Jeffamine M-1000, Jeffamine M-2005, Jeffamine M-2070 manufactured by HUNTSMAN. is mentioned. These may be used alone or in combination of two or more.
• the quaternary ammonium salt compound that modifies nanocellulose is not particularly limited.
• Specific examples of quaternary ammonium salt compounds include quaternary ammonium hydroxides such as tetrabutylammonium hydroxide, quaternary ammonium chlorides such as tetrabutylammonium chloride, and quaternary ammonium chlorides such as tetrabutylammonium bromide.
• Quaternary ammonium iodides such as primary ammonium bromide, tetrabutylammonium iodide, and the like are conceivable.
• the nanocellulose in the present invention is produced by a method comprising, for example, a step A of oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof to obtain oxidized cellulose, and optionally a step B of fibrillating the oxidized cellulose. can do.
• the cellulosic raw material is not particularly limited as long as it is mainly composed of cellulose, and examples thereof include pulp, natural cellulose, regenerated cellulose, and fine cellulose depolymerized by mechanically treating cellulose.
• the cellulosic raw material commercially available products such as crystalline cellulose made from pulp can be used as they are.
• unused biomass containing a large amount of cellulose components, such as bean curd refuse and soybean hulls may be used as a raw material.
• the cellulosic raw material may be preliminarily treated with an alkali of an appropriate concentration for the purpose of facilitating penetration of the oxidizing agent to be used into the raw pulp.
• Hypochlorous acid or salts thereof used for oxidizing cellulosic raw materials include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite. is mentioned. Among these, sodium hypochlorite is preferable from the viewpoint of ease of handling.
• a method of producing oxidized cellulose by oxidation of a cellulosic raw material includes a method of mixing a cellulosic raw material with a reaction solution containing hypochlorous acid or a salt thereof.
• the solvent contained in the reaction solution is preferably water because it is easy to handle and hardly causes side reactions.
• the amount of hypochlorous acid or its salt used is not particularly limited, but it is preferable to use hypochlorous acid or its salt having an available chlorine concentration of 6% by mass or more and 43% by mass or less.
• hypochlorous acid or a salt thereof with an available chlorine concentration of 6% by mass or more and 43% by mass or less, the amount of carboxyl groups in the oxidized cellulose can be sufficiently increased, the fineness is sufficiently advanced, and after the oxidation reaction can omit the mechanical defibration process.
• the effective chlorine concentration of hypochlorous acid or its salt in the reaction solution (reaction system) is preferably in the range of 6 to 43% by mass.
• the effective chlorine concentration of the reaction solution is more preferably 14% by mass or more, still more preferably 18% by mass or more, and even more preferably 20% by mass or more. is.
• the effective chlorine concentration of the reaction solution is more preferably 40% by mass or less, and still more preferably 38% by mass or less.
• the range of effective chlorine concentration of the reaction liquid the aforementioned lower limit and upper limit can be appropriately combined.
• the effective chlorine concentration range is more preferably 16 to 43% by mass, more preferably 18 to 40% by mass.
• the effective chlorine concentration range is preferably 6% by mass or more and less than 14% by mass, more preferably 7% by mass or more and less than 14% by mass. It is more preferably 7% by mass or more and 13% by mass or less, and even more preferably 8% by mass or more and 13% by mass or less.
• hypochlorous acid is a weak acid that exists as an aqueous solution
• hypochlorites are compounds in which hydrogen in hypochlorous acid is replaced with other cations.
• sodium hypochlorite which is hypochlorite
• the concentration is measured as the amount of available chlorine in the solution, not the concentration of sodium hypochlorite. .
• the oxidation reaction of cellulosic raw materials with hypochlorous acid or its salts should be carried out while adjusting the pH within the range of 5.0 to 14.0. Within this range, the oxidation reaction of the cellulosic raw material can be sufficiently advanced, and the amount of carboxyl groups in the oxidized cellulose can be sufficiently increased. This makes it possible to easily defibrate the oxidized cellulose.
• the pH of the reaction system is more preferably 7.0 or higher, still more preferably 8.0 or higher, even more preferably 8.5 or higher, still more preferably 9.0 or higher, and still more preferably 9.5 or higher.
• the upper limit of the pH of the reaction system is not particularly limited, and is preferably 14.5 or less, more preferably 14.0 or less, still more preferably 13.0 or less, still more preferably 12.5 or less, and still more preferably 12.5 or less. It is preferably 12.0 or less, more preferably 11.5 or less.
• the pH range of the reaction system is more preferably 7.0 to 14.0, still more preferably 8.0 to 13.5, still more preferably 8.5 to 13.0.
• an alkaline agent such as sodium hydroxide
• an acid such as hydrochloric acid
• the method for producing oxidized cellulose will be further described below, taking as an example the case where sodium hypochlorite is used as hypochlorous acid or a salt thereof.
• the reaction solution is preferably an aqueous sodium hypochlorite solution.
• the effective chlorine concentration of the sodium hypochlorite aqueous solution to the desired concentration (for example, the desired concentration: the range of 6% by mass to 43% by mass)
• hypochlorite with a lower effective chlorine concentration than the desired concentration A method of concentrating a sodium hypochlorite aqueous solution, a method of diluting a sodium hypochlorite aqueous solution with a higher effective chlorine concentration than the target concentration, and sodium hypochlorite crystals (e.g., sodium hypochlorite pentahydrate) Examples include a method of dissolving in a solvent.
• adjusting the effective chlorine concentration as an oxidizing agent by a method of diluting a sodium hypochlorite aqueous solution or a method of dissolving sodium hypochlorite crystals in a solvent is less self-decomposing (i.e., It is preferable because the decrease in the available chlorine concentration is small) and the adjustment of the available chlorine concentration is simple.
• the method of mixing the cellulosic raw material and the sodium hypochlorite aqueous solution is not particularly limited, but from the viewpoint of ease of operation, it is preferable to add the cellulosic raw material to the sodium hypochlorite aqueous solution and mix.
• the method of stirring includes, for example, a stirrer with stirring blades, a homomixer, a disper-type mixer, a homogenizer, external circulation stirring, and the like.
• shear type stirrers such as homomixers and homogenizers, stirrer with stirring blades, and A method using one or more of disper-type mixers is preferred, and a method using a stirrer with stirring blades is particularly preferred.
• stirrer with stirring blades When using a stirrer with stirring blades, propeller blades, paddle blades, turbine blades, swept blades, anchor blades, gate blades, Maxblend blades, full zone blades, helical ribbon blades, screw blades (with draft tubes, etc.) ) or the like can be used. When using a stirrer with stirring blades, it is preferable to stir at a rotational speed of 50 to 300 rpm. In addition, multi-screw kneaders such as single-screw kneaders and twin-screw kneaders can also be used.
• the reaction temperature in the oxidation reaction is preferably 15°C to 100°C, more preferably 20°C to 90°C.
• the reaction time of the oxidation reaction can be set according to the degree of progress of the oxidation, but is preferably about 15 minutes to 50 hours.
• the pH of the reaction system is set to 10 or higher, it is preferable to set the reaction temperature to 30° C. or higher and/or the reaction time to 30 minutes or longer.
• the pressure during the reaction is not particularly limited, but is usually in the range of normal pressure to 1.0 MPaG (gauge pressure, hereinafter the same).
• normal pressure means a pressure amount equal to the atmospheric pressure. Oxidation under pressure tends to reduce the amount of hypochlorous acid or a salt thereof to be used and to produce oxidized cellulose more efficiently.
• the pressure is preferably 0.1 MPaG or more and 1.0 MPaG or less.
• the effective chlorine concentration of hypochlorous acid or a salt thereof may be more than 0% by mass and 43% by mass or less, and from the viewpoint of improving efficiency, it is preferably 0.1% by mass or more and 20% by mass or less. , more preferably 1.0% by mass or more and 15% by mass or less, and still more preferably 1.0% by mass or more and 10% by mass or less.
• a treatment may be performed to stop the oxidation reaction.
• the treatment for stopping the oxidation reaction is not particularly limited, but examples thereof include a method of adding an acid or a metal catalyst. Moreover, the method of reducing hypochlorous acid or its salt is suitably mentioned. Specific examples of the treatment for stopping the oxidation reaction include a method of adding a reducing agent such as sodium sulfite. The amount of the reducing agent to be added may be appropriately adjusted according to the amount of hypochlorous acid or its salt (effective chlorine concentration).
• Oxidized cellulose can be obtained as an oxide of In the isolation treatment, some or all of the carboxyl groups in the oxidized cellulose may be converted to H-type (--COOH) by adjusting the pH of the solution containing the oxidized cellulose to 4 or less.
• the solution containing oxidized cellulose obtained by the above reaction may be used as it is, or may be subjected to the following fibrillation step, for example.
• the cellulose fibers after the oxidation treatment may be reduced with a reducing agent, if necessary. As a result, at least part of the aldehyde group and ketone group is reduced to return to a hydroxyl group. Note that the carboxy group is not reduced.
• the total content of carbonyl groups (aldehyde groups and ketone groups) in the oxidized cellulose obtained by this reduction, calculated by the semicarbazide method described later, is not particularly limited, and is usually 0.3 mmol/g or less. It may be 0.1 mmol/g or less.
• reducing agent used in the above reduction reaction common reducing agents can be used, and examples include borates, sulfites, and the like. Coloring can be prevented by using these reducing agents.
• the borates are a generic term for borates and boronates.
• the borate in the present invention refers to a salt composed of an anion derived from boric acid (B(OH) 3 ) and a monovalent metal ion.
• borates are M 3 [BO 3 ], M 2 [HBO 3 ], M[H 2 BO 3 ], M 2 [R-BO 2 ] or M[R-BO 2 H].
• M is a monovalent metal ion
• R is a monovalent hydrocarbon group
• These borates may be present in the composition of the invention as a solid, ionized, or reacted with the functional groups of the nanocellulose.
• borate salts include sodium borate, lithium borate, potassium borate, rubidium borate, cesium borate, sodium borate, potassium borate, rubidium borate, and cesium borate. be done.
• the amount of the borate salt may be in the range of 1 to 30% by mass with respect to the absolute dry mass of the oxidized cellulose.
• the above sulfites include sulfite (M 2 SO 3 : M is a monovalent cation moiety), hydrogen sulfite (MHSO 3 : M is a monovalent cation moiety), pyrosulfite (M 2 S 2 O 5 or M'S 2 O 5 : M is a monovalent cation moiety, M' is a divalent cation moiety), hyposulfite (M 2 S 2 O 4 or M'S 2 O 4 : M is a monovalent (M' is a divalent cation moiety), or hydrates thereof.
• M include alkali metal ions and ammonium ions
• examples of M′ include alkaline earth metal ions.
• sulfites include sodium hydrogen sulfite, potassium hydrogen sulfite, ammonium hydrogen sulfite, sodium sulfite, potassium sulfite, ammonium sulfite, sodium hyposulfite, potassium hyposulfite, calcium hyposulfite, sodium pyrosulfite, and potassium pyrosulfite. , magnesium pyrosulfite, calcium pyrosulfite and the like.
• the amount of sulfites is preferably 0.1 to 15% by mass, more preferably 1 to 15% by mass, still more preferably 1.0 to 12% by mass, and 3.0 to 10% by mass relative to the absolute dry mass of oxidized cellulose. % by mass is even more preferred.
• the reduction treatment temperature should be about 10 to 90°C in terms of the efficiency of the reduction treatment and suppression of fiber deterioration.
• the pH at the reduction treatment may be appropriately adjusted depending on the reducing agent to be used, and is usually in the range of pH 2-12.
• the reaction time in the reduction reaction can be appropriately set according to the degree of progress of the reduction, and is not particularly limited.
• the oxidized cellulose is preferably in the form of a dispersion.
• the dispersion as used herein is a suspension containing oxidized cellulose.
• the dispersion liquid may contain the solvent used in the oxidation. Alternatively, a dispersion medium may be appropriately added to form a dispersion liquid. Since the oxidized cellulose is a dispersion liquid, it is easy to handle, and tends to facilitate the progress of miniaturization.
• the amount of the oxidized cellulose is usually in the range of 0.1% by mass or more and 95% by mass or less, preferably 1% by mass, when the total amount of the dispersion is 100% by mass. % or more and 50 mass % or less, more preferably 1 mass % or more and 30 mass % or less.
• Oxidized cellulose includes fibrous cellulose obtained by oxidizing a cellulosic raw material using hypochlorous acid or a salt thereof. Oxidized cellulose is also referred to as oxidized cellulose fiber. That is, oxidized cellulose includes oxides of cellulosic raw materials with hypochlorous acid or salts thereof. The main component of plants is cellulose, and bundles of cellulose molecules are called cellulose microfibrils. Cellulose in cellulosic raw materials is also contained in the form of cellulose microfibrils.
• Nanocellulose can be obtained by fibrillating the oxidized cellulose obtained above to make it nano, if necessary.
• methods for defibrating oxidized cellulose include weak stirring using a magnetic stirrer and the like, mechanical fibrillation, and the like.
• Mechanical fibrillation methods include, for example, a screw type mixer, a paddle mixer, a disper type mixer, a turbine type mixer, a homogenizer under high speed rotation, a high pressure homogenizer, an ultrahigh pressure homogenizer, a double cylindrical homogenizer, and an ultrasonic homogenizer. , water jet counter-collision disperser, beater, disc refiner, conical refiner, double disc refiner, grinder, single or multi-screw kneader, rotation or revolution stirrer, vibration stirrer, etc. method.
• Nanocellulose can be produced by nanoizing oxidized cellulose by using one or more of these devices, preferably by treating oxidized cellulose in a dispersion medium.
• a method using an ultra-high-pressure homogenizer can be preferably used in that it can produce nanocellulose with more advanced fibrillation.
• the pressure during fibrillation treatment is preferably 100 MPa or higher, more preferably 120 MPa or higher, and still more preferably 150 MPa or higher.
• the number of defibration treatments is not particularly limited, it is preferably two or more, more preferably three or more, from the viewpoint of sufficiently progressing defibration.
• the oxidized cellulose can be sufficiently fibrillated by gentle stirring using a rotation/revolution stirrer, a vibrating stirrer, or the like. Examples of vibratory stirrers include vortex mixers (touch mixers). That is, according to the oxidized cellulose, uniform nanocellulose can be obtained even when the defibration treatment is performed under mild defibration conditions.
• the defibration treatment is preferably carried out while the oxidized cellulose is mixed with a dispersion medium.
• the dispersion medium is not particularly limited and can be appropriately selected depending on the purpose. Specific examples of dispersion media include water, alcohols, ethers, ketones, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethylsulfoxide. As the solvent, one of these may be used alone, or two or more thereof may be used in combination.
• alcohols include methanol, ethanol, isopropanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, methyl cellosolve, ethylene glycol and glycerin.
• Ethers include ethylene glycol dimethyl ether, 1,4-dioxane and tetrahydrofuran.
• Ketones include acetone and methyl ethyl ketone.
• the nanocellulose in the present invention preferably satisfies the following zeta potential and light transmittance.
• the zeta potential of nanocellulose in the present invention is preferably -30 mV or less.
• the zeta potential is ⁇ 30 mV or less (that is, the absolute value is 30 mV or more)
• sufficient repulsion between microfibrils is obtained, and nanocellulose with a high surface charge density is likely to be produced during mechanical fibrillation.
• the dispersion stability of the nanocellulose is improved, and the viscosity stability and handleability when made into a slurry can be improved.
• the upper limit of the zeta potential is not particularly limited, it is usually -100 mV or less.
• the zeta potential is -100 mV or more (that is, the absolute value is 100 mV or less)
• oxidative cutting in the fiber direction tends to be suppressed as oxidation progresses, so nanocellulose with a uniform size can be obtained.
• the nanocellulose is stable and highly dispersible in water, and the resulting water-based ink composition contains nanocellulose uniformly.
• the zeta potential of nanocellulose is preferably ⁇ 35 mV or less, more preferably ⁇ 40 mV or less, and even more preferably ⁇ 50 mV or less.
• the lower limit of the zeta potential is preferably ⁇ 90 mV or more, more preferably ⁇ 85 mV or more, further preferably ⁇ 80 mV or more, even more preferably ⁇ 77 mV or more, even more preferably ⁇ 70 mV or more, and more preferably ⁇ 65 mV or more. More preferred.
• the aforementioned lower limit and upper limit can be appropriately combined.
• the zeta potential is preferably ⁇ 90 mV or more and ⁇ 30 mV or less, more preferably ⁇ 85 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 80 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 77 mV or more and ⁇ 30 mV or less. more preferably ⁇ 70 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 65 mV or more and ⁇ 30 mV or less, and still more preferably ⁇ 65 mV or more and ⁇ 35 mV or less.
• the zeta potential is a value measured under conditions of pH 8.0 and 20° C.
• a cellulose aqueous dispersion in which nanocellulose and water are mixed to have a nanocellulose concentration of 0.1% by mass.
• it can be measured according to the conditions described below.
• a 0.05 mol/L sodium hydroxide aqueous solution was added to the diluted nanocellulose aqueous dispersion to adjust the pH to 8.0, and the zeta potential was measured at 20°C using a zeta potential meter (ELSZ-1000) manufactured by Otsuka Electronics Co., Ltd. Measure in
• a nanocellulose dispersion obtained by dispersing nanocellulose in a dispersion medium according to the present invention can exhibit high light transmittance with little light scattering of cellulose fibers.
• the nanocellulose in the present invention preferably has a light transmittance of 95% or more in a liquid mixture obtained by mixing with water to a solid content concentration of 0.1% by mass.
• the light transmittance is more preferably 96% or higher, still more preferably 97% or higher, and even more preferably 99% or higher.
• the light transmittance is a value measured with a spectrophotometer at a wavelength of 660 nm.
• light transmittance can be measured using an aqueous dispersion containing nanocellulose. Specifically, it can be measured according to the conditions described in the examples below.
• the zeta potential and light transmittance can be controlled by oxidizing with hypochlorous acid or a salt thereof, and in particular by adjusting the reaction time, reaction temperature, stirring conditions, etc. of the oxidation reaction. Specifically, as the reaction time is lengthened and/or the reaction temperature is raised, oxidation of the cellulose microfibril surface in the cellulosic raw material progresses, and repulsion between fibrils occurs due to electrostatic repulsion and osmotic pressure. Strengthening tends to result in smaller average fiber widths.
• the zeta potential can be increased by setting one or more of the oxidation reaction time, reaction temperature, and stirring conditions (e.g., lengthening the reaction time) so that oxidation proceeds more (i.e., increases the degree of oxidation). It tends to be higher.
• the nanocellulose in the present invention is obtained by defibrating after obtaining oxidized cellulose using hypochlorous acid or a salt thereof.
• the degree of polymerization of the oxidized cellulose used in the present invention is preferably 600 or less. If the degree of polymerization of the oxidized cellulose exceeds 600, it tends to require a large amount of energy for defibration, and sufficient fibrillation properties cannot be exhibited, resulting in a decrease in the dispersibility of the pigment and, in turn, a decrease in the optical density. tend to In addition, when the degree of polymerization of oxidized cellulose exceeds 600, the amount of oxidized cellulose that is insufficiently fibrillated increases. May lose transparency.
• the size of the obtained nanocellulose tends to vary, resulting in non-uniform quality.
• the viscosity of the ink composition containing nanocellulose increases, and the ejection stability in inkjet printing may decrease.
• the lower limit of the degree of polymerization of oxidized cellulose is not particularly set. However, if the degree of polymerization of the oxidized cellulose is less than 50, the proportion of particulate cellulose rather than fibrous cellulose is increased, and the scratch resistance of the resulting coating film may be reduced. From the above viewpoint, the degree of polymerization of oxidized cellulose is preferably in the range of 50 or more and 600 or less.
• the degree of polymerization of oxidized cellulose is more preferably 580 or less, still more preferably 560 or less, still more preferably 550 or less, still more preferably 500 or less, still more preferably 450 or less, and More preferably, it is 400 or less.
• the lower limit of the degree of polymerization is more preferably 60 or more, still more preferably 70 or more, still more preferably 80 or more, and still more preferably from the viewpoint of improving viscosity stability and coatability of the slurry. is 90 or more, more preferably 100 or more, even more preferably 110 or more, and particularly preferably 120 or more.
• a preferred range of the degree of polymerization can be determined by appropriately combining the above-mentioned upper limit and lower limit.
• the degree of polymerization of the chemically modified cellulose is more preferably 60 to 600, still more preferably 70 to 600, still more preferably 80 to 600, still more preferably 80 to 550, It is preferably 80-500, more preferably 80-450, and particularly preferably 80-400.
• the degree of polymerization of oxidized cellulose can be adjusted by changing the reaction time, reaction temperature, pH, effective chlorine concentration of hypochlorous acid or its salt, etc. during the oxidation reaction. Specifically, since the degree of polymerization tends to decrease when the degree of oxidation is increased, methods of reducing the degree of polymerization include, for example, increasing the reaction time and/or reaction temperature for oxidation. As another method, the degree of polymerization of oxidized cellulose can be adjusted by the stirring conditions of the reaction system during the oxidation reaction. For example, under conditions in which the reaction system is sufficiently homogenized using a stirring blade or the like, the oxidation reaction tends to proceed smoothly and the degree of polymerization tends to decrease.
• the degree of polymerization of oxidized cellulose tends to vary depending on the selection of raw material cellulose. Therefore, the degree of polymerization of oxidized cellulose can be adjusted by selecting a cellulosic raw material.
• the degree of polymerization of oxidized cellulose is the average degree of polymerization (viscosity average degree of polymerization) measured by the viscosity method. The details follow the method described in the examples below.
• the aqueous ink composition of the present invention contains an aqueous medium such as a water-soluble solvent and/or water as a solvent.
• Water may be used alone, or a mixed solvent of water and a water-soluble solvent may be used.
• Water-soluble solvents include, for example, ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and methyl isobutyl ketone; alcohols; ethers such as tetrahydrofuran, 1,4-dioxane and 1,2-dimethoxyethane; and amides such as 2-pyrrolidone, dimethylformamide and N-methylpyrrolidone.
• glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol; butanediol, pentanediol, hexanediol, and these Glycol esters such as propylene glycol laurate; Cellosolves including diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl ethers, propylene glycol ethers, dipropylene glycol ethers, and triethylene glycol ethers sulfolane; lactones such as ⁇ -butyrolactone; lactams such as N-(2-hydroxyethyl
• the ink composition of the present invention contains at least one pigment selected from known and commonly used organic pigments and inorganic pigments. Moreover, both untreated pigments and treated pigments can be applied to the pigments in the present invention.
• the treated pigments also include so-called self-dispersing pigments.
• a self-dispersing pigment is produced, for example, by subjecting a pigment to physical or chemical treatment to bond (graft) a hydrophilic group to the surface of the pigment.
• yellow ink, cyan ink, magenta ink, black ink, etc. are used singly or as a combination of multiple ink sets.
• the pigments used for these are not particularly limited, and those commonly used as pigments for water-based inks can be used. Specifically, it can be dispersed in water or a water-soluble organic solvent, and known inorganic pigments and organic pigments can be used. Examples of inorganic pigments include iron oxide, carbon black produced by known methods such as the contact method, the furnace method, and the thermal method.
• Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinoflurone pigments, etc.), dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like.
• azo pigments including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.
• polycyclic pigments e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments,
• a pigment used in black ink for example, as carbon black, Mitsubishi Chemical Corporation's No. 2300, No. 2200B, No. 900, No. 960, No. 980, No. 33, No. 40, No, 45, No. 45L, No. 52, HCF88, MA7, MA8, MA100, etc. are Columbia's Raven5750, Raven5250, Raven5000, Raven3500, Raven1255, Raven700, etc. are Cabot's Regal 400R, Regal 330R, Regal 660R, Mogul 00L, 7Mol, 7M Monarch800, Monarch880, Monarch900, Monarch1000, Monarch1100, Monarch1300, Monarch1400, etc.
• Pigments used in yellow ink include, for example, C.I. I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, 185 and the like.
• Pigments used in magenta ink include, for example, C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 146, 168, 176, 184, 185, 202, 209, etc. .
• Pigments used in cyan ink include, for example, C.I. I. Pigment Blue 1, 2, 3, 15, 15:3, 15:4, 16, 22, 60, 63, 66 and the like.
• the self-dispersion pigment for example, a commercially available product may be used.
• Commercially available products include, for example, "CAB-O-JET200”, “CAB-O-JET250C”, “CAB-O-JET260M”, “CAB-O-JET270Y”, “CAB- O-JET300", “CAB-O-JET400", “CAB-O-JET450C”, “CAB-O-JET465M” and “CAB-O-JET470Y”;”BONJET BLACK CW-2” manufactured by Orient Chemical Industry Co., Ltd. and “BONJET BLACK CW-3”;”LIOJET WD BLACK 002C” manufactured by Toyo Ink Mfg.
• a pigment dispersion obtained by dispersing a self-dispersing pigment in an aqueous medium can also be used.
• a pigment dispersion obtained by dispersing a self-dispersing pigment in an aqueous medium can also be used.
• the pigment content (based on mass) may be in the range of 0.5 to 30% with respect to the total amount of water-based ink.
• the particle size of the pigment is preferably 1 ⁇ m or less, more preferably 10 nm to 150 nm particles, and still more preferably 50 nm to 120 nm particles.
• the content of nanocellulose used in the present invention is preferably in the range of 1/100 to 50/100, preferably 1/100 to 30, when the ratio (nanocellulose/pigment) in water-based ink is based on mass. It is more preferably in the range of /100, more preferably in the range of 3/100 to 30/100. Within the above range, the resulting image tends to exhibit good color development and abrasion resistance without impairing suitability for various printing methods.
• the content of nanocellulose is preferably 0.001 to 3% by mass, more preferably 0.01 to 2% by mass, and further preferably 0.01 to 2% by mass, based on the total mass of the ink composition. More preferably, it is in the range of 0.1 to 1.8% by mass. At a content of 0.001% or more, optical density and abrasion resistance can be easily ensured, and at a content of 3% or less, an increase in viscosity of the ink is suppressed, and printability tends to be excellent.
• the ink composition of the present invention contains at least the nanocellulose described above, but may contain other dispersants.
• an anionic group-containing organic polymer compound can be preferably used.
• the anionic group-containing organic polymer compound is mainly used for the purpose of dispersing the pigment, but since the compound is a polymer, it also functions as a binder.
• a binder component By including a binder component, the functionality of the coating film obtained from the ink composition, such as fastness, adhesion, and optical density, can be further enhanced.
• Known anionic group-containing organic polymer compounds can be used. Further, for detailed embodiments of the anionic group-containing organic polymer compound, reference can be made to International Publication No. 2015/166808.
• Anionic group-containing organic polymer compounds include, for example, organic polymer compounds containing a carboxy group, a sulfonic acid group, or a phosphoric acid group.
• Examples of such an anionic group-containing organic polymer compound include polyvinyl resins having an anionic group, polyester resins having an anionic group, amino resins having an anionic group, and acrylic resins having an anionic group.
• acrylic resins having anionic groups and polyurethane resins having anionic groups are preferable because they are abundant in raw materials, are easy to design, and are excellent in pigment dispersing function.
• the anionic group-containing organic polymer compounds used in the present invention can be used alone or in combination of two or more. By combining two or more types, the various properties of the water-based ink may be balanced.
• the acrylic resin having an anionic group is, specifically, a copolymerization of a monomer having an anionic group such as (meth)acrylic acid and another anionic group-containing organic polymer compound copolymerizable therewith.
• a resin composed of a coalescence can be mentioned.
• (meth)acrylic acid is a generic term for acrylic acid and methacrylic acid.
• esters of (meth)acrylic acid are interpreted in the same manner as above.
• Examples of monomers of anionic group-containing organic polymer compounds include styrene, ⁇ -methylstyrene, ⁇ -methylstyrene, 2,4-dimethylstyrene, ⁇ -ethylstyrene, ⁇ -butylstyrene and ⁇ -hexylstyrene.
• alkylstyrene such as, 4-chlorostyrene, 3-chlorostyrene, halogenated styrene such as 3-bromostyrene, further 3-nitrostyrene, 4-methoxystyrene, styrenic monomers such as vinyltoluene, and benzyl (meth)acrylate , phenyl(meth)acrylate, phenylethyl(meth)acrylate, phenylpropyl(meth)acrylate, and phenoxyethyl(meth)acrylate.
• styrene-based monomers such as styrene, ⁇ -methylstyrene and tert-butylstyrene.
• the copolymer related to the acrylic resin having an anionic group in the present invention preferably contains polymerized units of (meth)acrylic acid and other copolymerizable polymerized units as essential polymerized units. It may be an original copolymer or a ternary or higher multi-dimensional copolymer with other copolymerizable polymer units.
• Monomers of the anionic group-containing organic polymer compound include methyl acrylate, methyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-ethylbutyl acrylate, Acrylics such as 1,3-dimethylbutyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylbutyl methacrylate, pentyl methacrylate, heptyl methacrylate, nonyl methacrylate, etc.
• Acid esters and methacrylic acid esters 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, dimethylaminoethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxybutyl acrylate, ethyl- ⁇ -(hydroxymethyl) acrylate, dimethyl acrylic ester derivatives and methacrylic ester derivatives such as aminoethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; acrylic acid aryl esters such as phenyl acrylate, benzyl acrylate, phenylethyl acrylate, phenylethyl methacrylate; Aralkyl acrylic esters; monoacrylates or monomethacrylates of polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, and bisphenol A; maleins such as dimethyl maleate and diethyl maleate Acid dialkyl esters, vinyl
• the copolymer related to the acrylic resin having an anionic group used in the present invention may be a linear copolymer consisting only of polymerized units of a monoanionic group-containing organic polymer compound, or may have various cross-linking properties. It may be a copolymer containing a partially crosslinked portion obtained by copolymerizing a very small amount of an anionic group-containing organic polymer compound having
• Examples of monomers for such crosslinkable anionic group-containing organic polymer compounds include glycidyl (meth)acrylate, divinylbenzene, ethylene glycol di(meth)acrylate, and propylene glycol di(meth)acrylate. , polyethylene glycol di(meth)acrylate, poly(oxyethyleneoxypropylene)glycol di(meth)acrylate, tri(meth)acrylate of alkylene oxide adduct of glycerin, and other polyhydric alcohol poly(meth)acrylates.
• the reaction rate of each monomer used is considered to be substantially the same, and the charge ratio of each monomer is regarded as the content ratio in terms of mass of polymerized units of each monomer.
• the copolymer of the acrylic resin having an anionic group in the present invention can be synthesized by various known reaction methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization. In this case, a known and commonly used polymerization initiator, chain transfer agent (polymerization degree modifier), surfactant and antifoaming agent can be used in combination.
• the weight average molecular weight of the acrylic resin having an anionic group is preferably within the range of 5,000 to 20,000.
• its weight average molecular weight is preferably in the range of 5,000 to 20,000, more preferably in the range of 5,000 to 18,000. Above all, it is particularly preferable to be in the range of 5500 to 15000.
• the weight average molecular weight is a value measured by a GPC (gel permeation chromatography) method, and is a value converted into the molecular weight of polystyrene used as a standard substance.
• the anionic group-containing organic polymer compound used in the present invention is a styrene-acrylic acid copolymer, it has carboxy groups derived from acrylic acid monomers and methacrylic acid monomers, and its acid value is 50 to 220 (mgKOH/ g), more preferably 60 to 200 (mgKOH/g). When the acid value is 220 (mgKOH/g) or less, aggregation of the pigment tends to be more difficult to occur.
• the acid value in the present specification is a numerical value measured according to Japanese Industrial Standards "K0070: 1992. Test method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products". , is the amount of potassium hydroxide (mg) required to completely neutralize 1 g of resin.
• Polyurethane resin having anionic group Polyurethane resin having anionic group used in the present invention are specifically polyols and polyisocyanates having anionic groups such as carboxy groups and sulfonic acid groups, and if necessary, general-purpose anionic groups. urethane resins obtained by reacting polyols or chain extenders that do not contain polyols.
• polyols having a carboxyl group used in the present invention include esters obtained by reacting polyhydric alcohols with polybasic acid anhydrides, 2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid, 2, dihydroxyalkanoic acids such as 2-dimethylolbutanoic acid and 2,2-dimethylolvaleric acid; Preferred compounds include 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.
• polyols having a sulfonic acid group examples include dicarboxylic acids such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, 5[4-sulfophenoxy]isophthalic acid, salts thereof, and the low Examples include polyester polyols obtained by reacting with molecular weight polyols.
• diisocyanate used in the present invention examples include aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and 4,4-cyclohexyl.
• diisocyanate compounds such as methane diisocyanate, araliphatic diisocyanate compounds such as xylylene diisocyanate and tetramethylxylene diisocyanate, and aromatic diisocyanates such as toluylene diisocyanate and phenylmethane diisocyanate.
• General-purpose anionic-group-free polyols also include, for example, polyester polyols, polyether polyols, polyhydroxypolycarbonates, polyhydroxypolyacetals, polyhydroxypolyacrylates, polyhydroxypolyesteramides, and polyhydroxypolythioethers.
• polyester polyols, polyether polyols and polyhydroxy polycarbonates are preferred.
• One of these polyols may be reacted alone, or several of them may be mixed and reacted.
• a low-molecular-weight diol may be used in combination as appropriate for the purpose of adjusting the film hardness of printed matter. Examples include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol and the like.
• Chain extenders used in the present invention include, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,4-bis( ⁇ -hydroxyethoxy)benzene , 1,4-cyclohexanediol, diols such as xylylene glycol, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, 4,4′-diaminodiphenylmethane, tolylenediamine, 4,4′-diaminodicyclohexylmethane, etc.
• diols such as xylylene glycol, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, 4,4′-diaminodiphenylmethane, tolylenediamine, 4,4′-di
• the polyurethane resin is produced by, for example, reacting the polyol and the polyisocyanate in the absence of a solvent or in the presence of an organic solvent.
• the urethane resin having an anionic group formed by neutralization with a basic compound or the like described later is mixed in an aqueous medium to make it water-based, it is mixed with a chain extender as necessary. , can be produced by reacting
• the equivalent ratio of the isocyanate groups of the polyisocyanate is preferably in the range of 0.8 to 2.5, preferably 0.9 to It is more preferable to carry out in the range of 1.5.
• the weight average molecular weight of the polyurethane resin having an anionic group is preferably in the range of 5,000 to 500,000, more preferably 10,000 to 200,000, It is particularly preferred to use those between 15,000 and 100,000.
• the weight average molecular weight is a value measured by a GPC (gel permeation chromatography) method, and is a value converted into the molecular weight of polystyrene used as a standard substance.
• polyurethane resin it is preferable to use one having an acid value in the range of 2 to 200 (mgKOH/g), and the range of 2 to 100 (mgKOH/g) is preferable. It is preferable for improving the good water dispersion stability of.
• the acrylic resin having an anionic group and the polyurethane resin having an anionic group are preferably used after being neutralized with a basic compound.
• a basic compound can be used, for example, hydroxides of alkali metals such as potassium and sodium; carbonates of alkali metals such as potassium and sodium; carbonates of alkaline earth metals such as calcium and barium; ; inorganic basic compounds such as ammonium hydroxide, amines or quaternary ammonium salt compounds used for modifying nanocellulose, and the like.
• alkali metal hydroxides typified by potassium hydroxide, sodium hydroxide, and lithium hydroxide contribute to lowering the viscosity of aqueous pigment dispersions, and improve ejection stability when used as aqueous inkjet recording inks.
• potassium hydroxide is particularly preferred.
• Storage stability may be enhanced by using the same basic compound as that used for modifying nanocellulose.
• a polysaccharide derivative having an anionic group may be blended in the ink composition of the present invention.
• the polysaccharide derivative having an anionic group is not particularly limited as long as it is a polyanionic polysaccharide.
• natural polysaccharides such as hyaluronic acid, alginic acid, pectin, polygalacturonic acid, carboxymethyl pullulan, carboxymethyl chitin, carboxymethyl chitosan, carboxymethyl mannan, carboxymethyl starch, carboxymethyl dextran, carboxymethyl cellulose
• Examples include carboxyalkyl polysaccharides such as carboxyethyl cellulose and carboxymethyl pullulan, oxidized polysaccharides such as oxidized cellulose and oxidized starch, and polysaccharides containing sulfate groups such as chondroitin sulfate, dermatan sulfate, heparin and heparan sulfate.
• the weight-average molecular weight of the raw material polysaccharide is not particularly limited, but it may generally be in the range of 50,000 to 1,000,000, and may be in the range of 50,000 to 500,000.
• the polysaccharide derivative having an anionic group in the present invention preferably forms a salt with a cation.
• a cation that forms a salt with the polysaccharide derivative having an anionic group
• protons and metal ions specifically metal ions such as sodium, potassium, lithium, calcium, and magnesium, and organic ions such as organic ammonium. cations are mentioned.
• carboxymethylcellulose sodium salt and carboxymethylcellulose ammonium salt are preferable because they are easily available and the desired effect can be easily obtained, and carboxymethylcellulose ammonium salt is particularly preferable because of its large viscosity-reducing effect.
• These anionic group-containing polysaccharide derivatives may be used alone or in combination of two or more.
• the degree of etherification (degree of substitution; DS) and the degree of neutralization of the polysaccharide derivative having an anionic group used in the present invention, particularly the sodium salt and ammonium salt of carboxymethylcellulose, are particularly limited.
• the viscosity of a 1% by mass aqueous solution measured at a rotor speed of 60 rpm and 25 ° C. with a Brookfield viscometer is usually in the range of 300 to 7000 mPa s, and is in the range of 500 to 5000 mPa s.
• the "etherification degree” is a numerical value indicating the average number of hydroxyl groups in which carboxymethyl groups are ether-bonded among the three hydroxyl groups contained in anhydroglucose, which is a constituent unit of cellulose, in carboxymethyl cellulose. be. Therefore, the value is theoretically between 0 and 3.
• the blending amount of the polysaccharide derivative having an anionic group is not particularly limited, and an appropriate amount is blended according to the above-mentioned purposes.
• the weight part of the polysaccharide derivative having an anionic group is 1 part by weight of the nanocellulose. , may be 5 or less, 3 or less, or 2 or less.
• carboxymethylcellulose sodium and carboxymethylcellulose ammonium can be used.
• the Celogen series sold by Daiichi Kogyo Seiyaku Co., Ltd. the CMC Daicel series sold by Daicel Finechem Co., Ltd.
• the Sunrose F series sold by Nippon Paper Chemicals Co., Ltd. can be used.
• carboxymethylcellulose ammonium include the DN series sold by Daicel Finechem Co., Ltd., and the like.
• the content (based on mass) of the anionic group-containing organic polymer compound used in the present invention is preferably 0.1 to 10 mass based on the total mass of the ink in the case of an aqueous pigment dispersion, especially for inkjet. %, more preferably 0.3-5%, and still more preferably 0.5-2%.
• the content is 0.1% or more, it becomes easy to secure abrasion resistance, and when the content is 10% or less, the viscosity increase of the ink is suppressed, and printability tends to be excellent.
• anionic group-containing organic polymer compound examples include Ajinomoto Fine-Techno Co., Inc.'s Ajisper PB series, BYK's DISPERBYK series and BYK-series, and BASF's Efka series.
• the water-based ink composition of the present invention may be diluted with a water-soluble solvent at any time as necessary, or may contain a wetting agent (drying inhibitor), a penetrating agent, a surfactant, and other additives.
• a wetting agent drying inhibitor
• a penetrating agent e.g., a surfactant
• surfactant e.g., a surfactant
• other additives e.g., a known and commonly used additive may be added.
• Such addition allows the ink to be used in various applications such as the field of paints for automobiles and building materials, the field of printing inks such as offset inks, gravure inks, flexographic inks and silk screen inks, and the field of inkjet recording inks.
• a step of centrifugation or filtration may be added to remove coarse particles.
• humectant is added for the purpose of preventing drying of the ink.
• the content of the humectant in the ink for the purpose of preventing drying is preferably 3 to 50% by mass.
• Wetting agents used in the present invention are not particularly limited, but examples include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3.
• -propylene glycol isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol and the like.
• containing propylene glycol and 1,3-butyl glycol is safe and has excellent effects on ink drying property and ejection performance in ink jet recording applications.
• the penetrant is added for the purpose of improving the permeability to the recording medium and adjusting the dot diameter on the recording medium.
• Penetrants include, for example, lower alcohols such as ethanol and isopropyl alcohol, ethylene oxide adducts of alkyl alcohols such as ethylene glycol hexyl ether and diethylene glycol butyl ether, and propylene oxide adducts of alkyl alcohols such as propylene glycol propyl ether.
• Surfactants are added to adjust ink properties such as surface tension.
• Surfactants that can be added for this purpose are not particularly limited, and include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and the like. Among them, anionic surfactants and nonionic surfactants are preferred.
• anionic surfactants include alkylbenzenesulfonates, alkylphenylsulfonates, alkylnaphthalenesulfonates, higher fatty acid salts, sulfuric acid ester salts of higher fatty acid esters, sulfonates of higher fatty acid esters, and higher alcohol ethers. Sulfuric acid ester salts and sulfonates, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc.
• Specific examples thereof include dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, and dibutylphenylphenoldisulfonate.
• nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, and glycerin fatty acid esters.
• polyoxyethylene glycerin fatty acid ester polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, fatty acid alkylolamide, alkylalkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers, among others, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid Esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid alkylolamides, acetylene glycol, oxyethylene adducts of acetylene glycol, polyethylene glycol polypropylene glycol block copolymers are preferred.
• surfactants include silicone-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers. spiculisporic acid, rhamnolipids, biosurfactants such as lysolecithin, and the like can also be used.
• surfactants can be used singly or in combination of two or more.
• the amount added is arbitrary, but it is usually in the range of 0.001 to 2% by mass with respect to the total mass of the ink.
• additives such as preservatives, viscosity modifiers, pH modifiers, chelating agents, plasticizers, antioxidants, and UV absorbers can be added.
• the water-based ink composition of the present invention exhibits high optical density and scratch resistance especially on plain paper. It can also be used with other absorbent recording members. Examples of the recording member include plain paper, (slightly) coated paper, fabric, ink-jet paper, ink-jet glossy paper, cardboard, wood, and the like, but are not limited to these.
• the recording method of the present invention includes a step of ejecting the water-based ink composition onto a recording member by an inkjet method.
• the details of the inkjet method are not particularly limited, and a known method may be adopted.
• the method for producing the water-based ink composition of the present invention is not particularly limited and can be obtained by a known method.
• the addition of nanocellulose or the like can be performed at any timing, regardless of whether it is before or after medialess dispersion, which will be described later.
• the ink composition of the present invention not only nanocellulose but also oxidized cellulose before nanoization can be used.
• a method of preparing an aqueous pigment dispersion containing at least a pigment and nanocellulose of the present invention by medialess dispersion by adding other additives as necessary A method of preparing a high-concentration aqueous dispersion (pigment paste), diluting it with an aqueous medium, and simultaneously adding other additives such as nano-cellulose as necessary.
• (1) Medialess dispersion of aqueous pigment dispersion specifically means ultrasonic dispersion method, high speed disk impeller, colloid mill, roll mill, high pressure homogenizer, nanomizer, Ultima A dispersion method using an isolator or the like can be used, but an ultrasonic dispersion method is preferable in consideration of productivity and contamination (mixture and contamination of foreign matter) due to abrasion of the media.
• the present invention will be described in detail below using an example using an ultrasonic dispersion method.
• the pigment and aqueous medium may be mixed and stirred as necessary before ultrasonic dispersion.
• the viscosity range at this time is usually from 0.1 to 100 mPa ⁇ s from the viewpoint of ensuring fluidity.
• the pigment concentration at this time is not particularly limited, and may be in the range of 1 to 30% by mass.
• Conditions for ultrasonic irradiation are not particularly limited, and can be performed at an output of 100 to 3000 W and a frequency of 15 to 40 kHz.
• the time for ultrasonic irradiation it is sufficient to secure a necessary and sufficient time for the pigment particles, nano-cellulose, etc. to be practically uniformly dispersed in the aqueous pigment dispersion.
• a power amount of 5 to 100 W/g is usually applied to the weight of the pigment contained in the dispersion.
• dispersion After irradiating the aqueous pigment dispersion with ultrasonic waves, dispersion may be further performed as necessary. Alternatively, dispersion and ultrasonic irradiation may be repeated.
• a dispersing device that can be used in this dispersing step, there are no particular limitations, and various known devices can be used. For example, sand mills, bead mills, pebble mills, ball mills, pearl mills, basket mills, attritors, dyno mills, bore mills, visco mills, motor mills, SC mills, dry mills, paint conditioners and other media dispersers, high-speed disk impellers, colloid mills, high-pressure homogenizers, and nanomizers. , medialess dispersers such as Ultimizer.
• the temperature of the aqueous pigment dispersion to be subjected to ultrasonic irradiation is not particularly limited, but it is preferable to apply ultrasonic waves while controlling the solidification point of the aqueous pigment dispersion to 70°C.
• the method for preparing the pigment paste in advance is not particularly limited, and a known dispersing method can be used.
• the following (i) to (iii) can be exemplified as methods for preparing this pigment paste.
• (i) A method of preparing a pigment paste by adding a pigment to an aqueous medium containing a pigment dispersant and water and then dispersing the pigment in the aqueous medium using a stirring/dispersing device.
• (ii) A pigment and a pigment dispersant are kneaded using a kneader such as a two-roller or a mixer, the resulting kneaded product is added to an aqueous medium containing water, and the pigment is mixed using a stirring/dispersing device. How to prepare a paste.
• the kneader is not particularly limited, and examples thereof include a Henschel mixer, a pressure kneader, a Banbury mixer, a planetary mixer and the like.
• the stirring/dispersing device is not particularly limited, and examples thereof include an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a dyno mill, a dispermat, an SC mill, and a nanomizer. One of these may be used alone, or two or more types of devices may be used in combination.
• the amount of pigment in the pigment paste should be 5 to 60% by mass.
• the impurities may be removed by ion exchange treatment or ultrafiltration treatment, and then post-treatment may be performed.
• ion exchange treatment ionic substances such as cations and anions (bivalent metal ions, etc.) can be removed, and by ultrafiltration treatment, impurity dissolved substances (residual substances during pigment synthesis, excess components in dispersion composition, etc.) can be removed. , resin not adsorbed to the organic pigment, contaminants, etc.) can be removed.
• a known ion exchange resin is used for the ion exchange treatment.
• the nanocellulose contained in the present invention is derived from oxidized cellulose, and the oxidized cellulose has easy fibrillation.
• the water-based ink composition of the present invention can also be made into a water-based ink composition containing nanocellulose by blending the oxidized cellulose with other materials of the water-based ink composition, and appropriately fibrillating and nanoizing.
• oxidized cellulose can be used in the production of aqueous ink compositions.
• the oxidized cellulose is fibrillated into nanocellulose in the composition by a dispersing operation or a kneading operation during production.
• the oxidized cellulose and materials other than the oxidized cellulose of the water-based ink composition are blended, and the mixture is defibrated by stirring such as dispersion or kneading operation, or the user of the oxidized cellulose himself/herself.
• Nanocellulose can be obtained by fibrillating and nanoizing.
• the agitation can be performed by the above-described (step B: fibrillation treatment).
• One aspect of the present invention is a method for producing a binder composition using oxidized cellulose containing an oxide of a cellulosic raw material by hypochlorous acid or a salt thereof and substantially free of an N-oxyl compound as a material. Specifically, in a method for producing an aqueous ink composition containing nanocellulose, a mixture containing oxidized cellulose and a material other than the nanocellulose of the aqueous ink composition is stirred to remove the oxidized cellulose. A production method including a step of defibrating to obtain the aqueous ink composition.
• one aspect of the present invention is a method for producing an aqueous ink composition containing nanocellulose, wherein oxidized cellulose is stirred and materials other than the nanocellulose of the aqueous ink composition are continuously mixed,
• the production method includes a step of defibrating the oxidized cellulose to obtain the water-based ink composition.
• aspects of the nanocellulose, oxidized cellulose, and aqueous ink composition are as described above.
• the material other than nanocellulose in the water-based ink composition is any material other than nanocellulose that can be contained in the water-based ink composition. It is not limited to these.
• continuous mixing the materials means performing in succession the pulverization of the oxidized cellulose by stirring and the addition of the materials.
• a specific embodiment in which stirring and addition are performed in series includes, for example, a mode in which the oxidized cellulose is stirred to make it finer and the above materials are added in one pot; Mode of adding material; and the like, but not limited to these.
• the oxidized cellulose when the oxidized cellulose is stirred to make at least a portion finer, it is not particularly limited as long as it is an operation for dispersing the components constituting the nanocellulose-containing composition. collision with inclusions or obstacles; ultrasonic waves; pressure loading; A submerged disperser can be suitably used for such a dispersing operation. Therefore, in one aspect of the production method of the present invention, stirring is performed by a submerged disperser.
• the submerged disperser is not particularly limited, and examples thereof include a homomixer, a magnetic stirrer, a stirring rod, a stirrer with stirring blades, a disper-type mixer, a homogenizer, an external circulation stirrer, a rotation-revolution stirrer, a vibrating stirrer, A method using an ultrasonic disperser or the like can be mentioned.
• Examples of the submerged disperser include, in addition to the devices described above, rotary shear type stirrers, colloid mills, roll mills, pressure homogenizers, container-driven mills, medium stirring mills, and the like.
• a kneader can be used as the submerged disperser.
• a rotary shear type agitator is a device that disperses a material to be agitated by passing it through a gap between a rotor blade and an outer cylinder.
• a colloid mill is a device that disperses by shear flow in the gap between rotating and stationary discs. Roll mills distribute shear and compression forces through the gaps between multiple rotating rolls.
• a pressure homogenizer is used as a disperser that discharges slurry or the like from pores at high pressure, and is also called a pressure injection disperser.
• a high pressure homogenizer is preferable as the pressure homogenizer.
• a high-pressure homogenizer is, for example, a homogenizer capable of discharging slurry at a pressure of 10 MPa or higher, preferably 100 MPa or higher.
• high-pressure homogenizers include counter-collision-type high-pressure homogenizers such as microfluidizers and wet jet mills.
• a container-driven mill is a device in which media such as balls in a container are dispersed by collision and friction.
• a medium agitation mill is a device that uses media such as balls and beads to disperse by the impact force and shear force of the media.
• a kneader is a device that performs an operation (also called kneading or kneading) to wet powder with a liquid.
• a Banbury mixer closed system, a device for dispersing under pressure
• a screw extruder a co-kneader, an extruder, and other extrusion type kneaders
• these devices may be used singly or in combination of two or more.
• the oxidized cellulose can be finely divided by stirring using such a device, the stirring may be performed until the constituent components of the nanocellulose-containing composition are homogenized or emulsified. As a result, the nanocellulose is uniformly dispersed in the nanocellulose-containing composition, and the nanocellulose-containing composition can be obtained as an emulsion.
• An aqueous ink composition containing nanocellulose obtained by a production method using oxidized cellulose can be recovered as an aqueous ink composition by appropriate post-treatment.
• the solvent used for the polymerization reaction of the anionic group-containing organic polymer compound may or may not be removed.
• the obtained product may be filtered and washed to form an aqueous ink composition.
• the presence of nanocellulose in the water-based ink composition of the present invention can be used as an indicator of the physical properties of the water-based ink composition. That is, it can be judged from the fact that the composition has a function caused by nanocellulose, for example, from the fact that the water-based ink composition has reached a slurry state or a viscosity state.
• the composition obtained by the production method of the present invention is in a slurry state, thickening occurs, precipitation of the formulation It can be determined that nanocellulose is included, because it does not occur.
• the composition obtained by the production method of the present invention has a slurry form equivalent to the above composition. and viscosity, it can be determined that it contains nanocellulose.
• nanocellulose-containing composition obtained by the production method of the present invention contains nanocellulose can be confirmed by transmission phase contrast observation with an optical microscope to determine whether the oxidized cellulose used remains coarse (the original oxidized cellulose is maintained). It can also be determined based on whether or not
• Light transmittance measurement A dispersion containing nanocellulose was placed in a quartz cell with a thickness of 10 mm, and light transmittance at a wavelength of 660 nm was measured using a spectrophotometer (JASCO V-550).
• Oxidized cellulose was added to an aqueous solution of sodium borohydride adjusted to pH 10, and reduction treatment was performed at 25° C. for 5 hours.
• the amount of sodium borohydride was 0.1 g per 1 g of oxidized cellulose.
• solid-liquid separation was performed by suction filtration, washing with water was performed, and the obtained oxidized cellulose was freeze-dried.
• 10 ml of 1 M copper ethylenediamine solution was added and dissolved.
• VP-1 pulp powder manufactured by TDI Co., Ltd.
• the pH during the reaction was adjusted to 11 while adding 48% by mass sodium hydroxide, and the reaction was continued for 30 minutes with a stirrer. Stirring was performed under these conditions. Thereafter, pure water was added to dilute the solution to 2 times, and sodium hydroxide was added to adjust the pH to 13, thereby slowing down the oxidation reaction and obtaining a cellulose-based oxide dispersed in water.
• hydrochloric acid was added to change the carboxy group of the cellulose oxide from the salt form (-COO - Na + ) to the proton form (-COO - H + ), thereby obtaining an aqueous dispersion having a pH of 2.5.
• the pH control in this example was performed using a pH controller (Tokyo Glass Instruments Co., Ltd., FD-02). Solid-liquid separation and washing were performed on the obtained aqueous dispersion of pH 2.5. Specifically, the supernatant is removed by centrifugation (1000 G, 10 minutes) and decantation, and an operation of adding an amount of pure water equivalent to the removed amount and sufficiently stirring with a spoon to homogenize is repeated six times.
• the above centrifugation and decantation were performed to obtain oxidized cellulose. Thereafter, sodium hydroxide was added in an amount approximately equimolar to the amount of the introduced carboxyl group to convert the carboxylic acid group from the proton type (-COO - H + ) to the salt type (-COO - Na + ). adjusted to 5.
• the temperature of the obtained aqueous dispersion slurry was set to 30° C., and 0.2 mmol/g of sodium borohydride was added to the cellulosic raw material, and the mixture was reacted for 2 hours for reduction treatment to obtain oxidized cellulose A.
• the content concentration of this oxidized cellulose was 10% by mass, the degree of polymerization (viscosity average degree of polymerization) of oxidized cellulose A was 90, and the amount of carboxy groups was 0.65 mmol/g.
• the effective chlorine concentration in the sodium hypochlorite aqueous solution was measured by the following method. (Measurement of effective chlorine concentration in sodium hypochlorite aqueous solution) Accurately weigh 0.582 g of an aqueous solution of sodium hypochlorite pentahydrate crystals added to pure water, add 50 ml of pure water, add 2 g of potassium iodide and 10 ml of acetic acid, immediately seal tightly and store in a dark place for 15 minutes. I left it.
• the liberated iodine was titrated with a 0.1 mol/L sodium thiosulfate solution (indicator, starch test solution), and the titration amount was 34.55 ml.
• a blank test was performed separately and corrected. Since 1 ml of 0.1 mol/L sodium thiosulfate solution corresponds to 3.545 mg Cl, the effective chlorine concentration in the sodium hypochlorite aqueous solution is 21% by mass.
• the nanocellulose I-2SX used in Comparative Examples 1 and 2 is nanocellulose obtained by being refined by TEMPO oxidation.
• I-2SX had a degree of polymerization (viscosity average degree of polymerization) of 461 and a carboxy group content of 2.0 mmol/g.
• a resin A having a monomer composition ratio of styrene/methacrylic acid/acrylic acid 77/13/10 (mass ratio), a weight average molecular weight of 8800, an acid value of 150 mgKOH/g and a glass transition point of 107° C. was prepared.
• MEK methyl ethyl ketone
• resin A 50 parts of methyl ethyl ketone
• resin A 50 parts of ion-exchanged water
• KOH potassium hydroxide
• polyether polyol (“PTMG2000” polytetramethylene glycol manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1000) 140.1 Parts by mass and 0.01 parts by mass of dibutyltin dilaurate (hereinafter referred to as DBTDL) were added, and the reaction was continued at 80°C. After confirming that the weight average molecular weight of the reactant reached the range of 20,000 to 50,000, 1.3 parts by mass of methanol was added to terminate the reaction. Then, 41.6 parts by mass of methyl ethyl ketone was added to obtain an organic solvent solution of urethane resin.
• PTMG2000 polytetramethylene glycol manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1000
• DBTDL dibutyltin dilaurate
• Part or all of the carboxy groups of the urethane resin are neutralized by adding 15.1 parts by mass of a 50% by mass aqueous solution of potassium hydroxide to the organic solvent solution of the urethane resin, and then 848.5 parts by mass of water is added. By adding and sufficiently stirring, a mixture containing urethane resin, methyl ethyl ketone and water, in which the urethane resin was dispersed or dissolved in the water, was obtained.
• Example 1 Preparation of aqueous ink composition>
• "#960” carbon black manufactured by Mitsubishi Chemical Corporation 60 parts
• anionic group-containing organic polymer compound solution (SA-1) 14 parts, triethylene glycol 20 parts, 2-pyrrolidone 20 parts was added, the pH was adjusted to between 9 and 10.5 with 34% potassium hydroxide, and pure water was added so that the total amount was 300 parts, and the mixture was stirred for 3 minutes at 120 RPM using a three-one motor.
• ultrasonic dispersion was performed for 10 minutes using an ultrasonic disperser (UP200St manufactured by Hielscher, operating frequency: 26 KHz, operating output: 160 W).
• Pure water was added to 30 parts of oxidized cellulose A (10% by mass) weighed in another container to adjust the concentration of oxidized cellulose to 1% by mass, followed by fibrillation (10,000 rpm, 10 minutes) with a homomixer. , to obtain nanocellulose A with an average fiber length of 200 nm and an average fiber width of 3 nm.
• a part of the aqueous dispersion of nanocellulose A obtained was taken out and pure water was added to prepare an aqueous dispersion with a solid content concentration of 0.1% by mass, and the light transmittance (660 nm) was 97%. It was confirmed that the oxidized cellulose was nanoized.
• Examples 2 to 10 In the same manner as in Example 1, except that the type of pigment used, the type and amount of anionic group-containing organic polymer compound added, and the type and amount of nanocellulose added were changed to those shown in Table 1, aqueous An ink composition was obtained.
• nanocelluloses A to C are derived from oxidized celluloses A to C, respectively.
• Example 11 In a metal beaker, 20 parts of oxidized cellulose A (10% by mass), 60 parts of "#960” (carbon black manufactured by Mitsubishi Chemical Corporation), an anionic group-containing organic polymer compound solution (SA-1) 14 parts, Add 20 parts of triethylene glycol and 20 parts of 2-pyrrolidone, adjust the pH to between 9 and 10.5 with 34% potassium hydroxide, add pure water so that the total amount is 300 parts, and mix. got This mixture was stirred and mixed for 3 minutes at 120 RPM using a three-one motor. Then, ultrasonic dispersion was performed for 10 minutes using an ultrasonic disperser (UP200St manufactured by Hielscher, operating frequency: 26 KHz, operating output: 160 W).
• UPM ultrasonic disperser
• the mixture was stirred and mixed for 3 minutes at 120 RPM using a three-one motor. Then, ultrasonic dispersion was performed for 10 minutes using an ultrasonic disperser (UP200St manufactured by Hielscher, operating frequency: 26 KHz, operating output: 160 W). From the dispersion liquid after dispersion, it was confirmed that the nanocellulose A had an average fiber length of 200 nm and an average fiber width of 3 nm. In addition, when a part of the aqueous dispersion of nanocellulose A was taken out and pure water was added to prepare an aqueous dispersion with a solid content concentration of 0.1% by mass, the light transmittance (660 nm) was 97%, and oxidation It was confirmed that the cellulose was nanoized.
• an ultrasonic disperser UPMSt manufactured by Hielscher, operating frequency: 26 KHz, operating output: 160 W.
• Pure water was added to 30 parts of I-2SX weighed in another container to adjust the content concentration to 1% by mass.
• the resulting liquid was filtered through a 1.2 ⁇ m membrane filter to obtain an aqueous ink composition of Comparative Example 1.
• Table 1 shows the charging amount and physical property evaluation results of the water-based ink composition.
• the method for evaluating the physical properties of the water-based ink composition is as follows.
• an aqueous pigment dispersion and an aqueous ink composition which are excellent in pigment dispersibility and which can easily form a coating film excellent in fastness, adhesion, color density, etc. at low cost. can provide.

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