Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
  • C08B15/02—Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
  • C08B15/04—Carboxycellulose, e.g. prepared by oxidation with nitrogen dioxide
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/72—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds
  • A61K8/73—Polysaccharides
  • A61K8/731—Cellulose; Quaternized cellulose derivatives
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q19/00—Preparations for care of the skin
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/02—Cellulose; Modified cellulose
  • C08L1/04—Oxycellulose; Hydrocellulose, e.g. microcrystalline cellulose
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
  • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
  • A61K2800/48—Thickener, Thickening system

Definitions

• the present invention relates to nanocellulose and its dispersion. More specifically, the present invention relates to nanocellulose obtained by defibrating the oxidized cellulose obtained by oxidizing the cellulose-based raw material with an oxidizing agent, and a nanocellulose dispersion containing the same.
• CNF cellulose nanofibers
• hypochlorous acid or a salt thereof is used as an oxidizing agent, and oxidized cellulose obtained by oxidizing a cellulose-based raw material under a high concentration condition in which the effective chlorine concentration in the reaction system is 14 to 43% by mass. It is disclosed that the fiber is defibrated and nano-sized.
• hypochlorous acid or a salt thereof is used as an oxidizing agent, the effective chlorine concentration in the reaction system is 6 to 14% by mass, and the pH is adjusted to 5.0 to 14.0 as a cellulose-based raw material. It is disclosed that the oxidized cellulose obtained by oxidizing the oxide is defibrated and nano-sized.
• the N-oxyl compound is used because the oxidation treatment is performed without using an N-oxyl compound such as 2,2,6,6-tetramethyl-1-piperidin-N-oxyradic (TEMPO) as a catalyst. Since it does not remain in the cellulose fiber, it is possible to produce the nanocellulose material while reducing the influence on the environment and the like.
• TEMPO 2,2,6,6-tetramethyl-1-piperidin-N-oxyradic
• the nanocellulose material may be used in a state of being dispersed in a dispersion medium such as water or an organic solvent in order to facilitate mixing with other materials (for example, resin). Further, the nanocellulose material may be mixed with inorganic particles such as pigments and a dispersion medium and used in a slurry state. In this case, the nanocellulose material is required to exhibit good dispersion stability in the dispersion medium.
• a dispersion medium such as water or an organic solvent in order to facilitate mixing with other materials (for example, resin).
• the nanocellulose material may be mixed with inorganic particles such as pigments and a dispersion medium and used in a slurry state. In this case, the nanocellulose material is required to exhibit good dispersion stability in the dispersion medium.
• the present invention has been made in view of the above circumstances, and a main object of the present invention is to provide nanocellulose which does not contain an N-oxyl compound in a cellulose fiber and has excellent dispersion stability in a dispersion medium. And.
• Nanocellulose which is an oxide of a cellulosic raw material made of hypochlorous acid or a salt thereof and has an average fiber width of 1 nm or more and 200 nm or less, which does not substantially contain an N-oxyl compound and has a zeta potential. Nanocellulose, which is -30 mV or less.
• Nanocellulose of [1] having an average fiber width of 1 nm or more and 5 nm or less.
• Nanocellulose which is an oxide of a cellulosic raw material made of hypochlorous acid or a salt thereof, does not contain an N-oxyl compound, and has an average fiber width of 1 nm or more and 5 nm or less.
• Nanocellulose which is an oxide of a cellulosic raw material made of hypochlorous acid or a salt thereof and has an average fiber width of 1 nm or more and 200 nm or less, does not contain an N-oxyl compound, and has an aspect ratio of 20 or more and 150.
• Nanocellulose which is an oxide of a cellulosic raw material made of hypochlorous acid or a salt thereof and has an average fiber width of 1 nm or more and 200 nm or less, does not contain an N-oxyl compound, and is solid when mixed with water. Nanocellulose having a light transmittance of 95% or more in a mixed solution having a component concentration of 0.1% by mass.
• a nanocellulose dispersion liquid in which the nanocellulose according to any one of [1] to [7] is dispersed in a dispersion medium.
• nanocellulose having excellent dispersion stability in a dispersion medium can be obtained. Moreover, since it does not contain an N-oxyl compound, it is possible to reduce the influence on the environment and the like.
• nanocellulose of the present disclosure is fibrous nanocellulose obtained by defibrating oxidized cellulose obtained by oxidizing a cellulose-based raw material with hypochlorous acid or a salt thereof. Further, the oxidized cellulose can also be said to be an oxide of a cellulosic raw material due to hypochlorous acid or a salt thereof.
• this nanocellulose will be described in detail.
• fibrous cellulose obtained by refining oxidized fibrous cellulose it is also referred to as "fine cellulose fiber”.
• Nanocellulose does not substantially contain an N-oxyl compound because the cellulosic raw material is oxidized with hypochlorous acid or a salt thereof.
• substantially free of N-oxyl compound means that the nanocellulose does not contain any N-oxyl compound, or the content of the N-oxyl compound is the total amount of nanocellulose. On the other hand, it means that it is 2.0 mass ppm or less, and is preferably 1.0 mass ppm or less. Further, even when the content of the N-oxyl compound is preferably 2.0 mass ppm or less, more preferably 1.0 mass ppm or less as an increase from the cellulosic raw material, "N-oxyl compound is substantially contained. It means “not included”.
• the N-oxyl compound is not substantially contained, it is possible to suppress the residual of the N-oxyl compound, which is concerned about the influence on the environment and the human body, in the nanocellulose.
• the content of the N-oxyl compound can be measured by a known means.
• a method using a trace total nitrogen analyzer can be mentioned.
• the nitrogen component derived from the N-oxyl compound in nanocellulose is measured as the amount of nitrogen using a trace total nitrogen analyzer (for example, manufactured by Mitsubishi Chemical Analytech Co., Ltd., device name: TN-2100H, etc.). be able to.
• the average fiber width of this nanocellulose is 1 to 200 nm.
• the average fiber width exceeds 200 nm, the proportion of coarse nanocellulose is large, so when nanocellulose is dispersed in a dispersion medium to form a nanocellulose dispersion, the quality tends to deteriorate due to the large amount of nanocellulose precipitation. .. Further, since the quality of the nanocellulose dispersion is not uniform, the viscosity of the slurry is unstable when a slurry containing solid particles such as pigments (hereinafter, also referred to as “nanocellulose-containing slurry”) is prepared. Handleability and coatability tend to deteriorate.
• the average particle size of the nanocellulose is preferably 50 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less. Further, when the average fiber width is less than 1 nm, it becomes close to the aspect of a cellulose single molecule, the quality as nanocellulose tends to be non-uniform, and the viscosity stability, handleability, and coatability deteriorate when the slurry is used. Tends to be easy. Therefore, the average fiber width is preferably 1.2 nm or more, more preferably 1.5 nm or more.
• the average fiber width of the nanocellulose is 1 to 5 nm
• the viscosity stability, handleability and coatability of the slurry are good when the nanocellulose-containing slurry is used. It is suitable for
• the aspect ratio (average fiber length / average fiber width) represented by the ratio of the average fiber width to the average fiber length is preferably 20 to 150.
• the aspect ratio is 150 or less, the network of fine cellulose is likely to be formed uniformly and densely in the dispersion medium, and the structure becomes stable, so that the dispersion stability can be improved.
• a network of solid particles and fine cellulose can be easily formed uniformly and densely, aggregation of solid particles can be suppressed, and dispersion stability can be improved.
• the aggregation of solid particles and nanocellulose or the aggregation of nanocellulose can be suppressed, and the handleability of the slurry can be improved and uneven processing can be suppressed.
• the aspect ratio is more preferably 145 or less, still more preferably 130 or less, still more preferably 120 or less, and even more preferably 100 or less.
• the aspect ratio is more preferably 30 or more, further preferably 35 or more, and even more preferably 40 or more.
• the average fiber width and average fiber length are such that nanocellulose and water are mixed so that the concentration of nanocellulose is approximately 1 to 10 ppm, and a sufficiently diluted cellulose aqueous dispersion is naturally dried on a mica substrate.
• Image processing software can be used to calculate such average fiber width and average fiber length. At this time, the image processing conditions are arbitrary, but the calculated values may differ depending on the image processing conditions even for the same image.
• the range of the difference in values depending on the image processing conditions is preferably within the range of ⁇ 100 nm for the average fiber length.
• the range of the difference in values depending on the conditions is preferably within the range of ⁇ 10 nm for the average fiber width.
• the nanocellulose preferably has a structure in which at least two of the hydroxyl groups of the glucopyranose ring constituting the cellulose are oxidized, and more specifically, the second and third positions of the glucopyranose ring. It has a structure in which a hydroxyl group is oxidized and a carboxy group is introduced. Further, it is preferable that the hydroxyl group at the 6-position of the glucopyranose ring in the present nanocellulose is not oxidized and remains as a hydroxyl group.
• the position of the carboxy group in the glucopyranose ring of nanocellulose can be analyzed by the solid 13 C-NMR spectrum.
• the peak corresponding to the carboxy group at the 2-position and the 3-position can be observed as a broad peak in the range of 165 ppm to 185 ppm.
• the broad peak here can be determined by the area ratio of the peak. That is, the ratio of the two peak area values (large area) obtained by vertically dividing the area value at the peak top after drawing a baseline on the peak in the range of 165 ppm to 185 ppm in the NMR spectrum to obtain the total area value.
• the ratio of the peak area value 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 baseline length L in the range of 165 ppm to 185 ppm and the perpendicular length L'from the peak top 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, but usually it may be 3.0 or less, 2.0 or less, or 1.0 or less.
• the structure of the above-mentioned glucopyranose ring of this nanocellulose can also be determined by analysis according to the method described in Sustainable Chem. Eng. 2020, 8, 48, 17800-17806.
• the nanocellulose has a zeta potential of ⁇ 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 having a high surface charge density is likely to be generated during mechanical defibration.
• the dispersion stability of nanocellulose is improved, and the viscosity stability, handleability, and coatability of the slurry can be improved.
• the lower limit of the zeta potential is not particularly limited.
• the zeta potential is -100 mV or more (that is, the absolute value is 100 mV or less)
• oxidative cleavage in the fiber direction with the progress of oxidation tends to be suppressed, so that nanocellulose having a uniform size can be obtained. And can demonstrate excellent coatability.
• the zeta potential of this 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 -90 mV or more is preferable, -85 mV or more is more preferable, -80 mV or more is further preferable, -77 mV or more is further preferable, -70 mV or more is further preferable, and -65 mV or more is more preferable. More preferred.
• the range of the zeta potential can be appropriately combined with the above-mentioned lower limit and upper limit.
• 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. Yes, more preferably ⁇ 70 mV or more and ⁇ 30 mV or less, still more preferably ⁇ 65 mV or more and ⁇ 30 mV or less, and even more preferably ⁇ 65 mV or more and ⁇ 35 mV or less.
• the zeta potential is a value measured under the conditions of pH 8.0 and 20 ° C. for a cellulose aqueous dispersion in which nanocellulose and water are mixed and the concentration of nanocellulose is 0.1% by mass. be. Specifically, the measurement can be performed according to the conditions described in Examples described later.
• the nanocellulose dispersion in which the present nanocellulose is dispersed in a dispersion medium has less light scattering of cellulose fibers and can exhibit high light transmittance.
• the nanocellulose has a light transmittance of 95% or more in a mixed solution having a solid content concentration of 0.1% by mass by mixing with water. Therefore, the present nanocellulose and the nanocellulose dispersion containing the same can be widely applied to applications requiring transparency and are useful.
• the light transmittance is more preferably 96% or more, further preferably 97% or more, still more preferably 99% or more.
• the light transmittance is a value measured by a spectrophotometer at a wavelength of 660 nm.
• the nanocellulose can be produced by a method including a step A of oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof to obtain oxidized cellulose and a step B of defibrating the oxidized cellulose. Since "oxidized cellulose” is oxidized fibrous cellulose, it is also referred to as "oxidized cellulose fiber”.
• the cellulosic raw material is not particularly limited as long as it is a material mainly composed of cellulose, and examples thereof include pulp, natural cellulose, regenerated cellulose, and fine cellulose depolymerized by mechanically treating cellulose.
• a commercially available product such as crystalline cellulose made from pulp can be used as it is.
• unused biomass containing a large amount of cellulose components such as okara and soybean skin may be used as a raw material.
• the cellulosic raw material may be treated with an alkali having an appropriate concentration in advance.
• hypochlorous acid or a salt thereof used for oxidation of cellulose-based raw materials examples include hypochlorous acid water, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, and ammonium hypochlorite. Can be mentioned. Of these, sodium hypochlorite is preferable from the viewpoint of ease of handling.
• Examples of the method for producing oxidized cellulose by oxidizing a cellulosic raw material include 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 side reactions are unlikely to occur.
• the effective chlorine concentration of hypochlorous acid or a salt thereof in the reaction solution is preferably 6 to 43% by mass, more preferably 7 to 43% by mass, and further preferably 10 to 43% by mass. , 14 to 43% by mass is more preferable.
• the effective chlorine concentration of the reaction solution is in the above range, the amount of carboxy groups in the cellulose oxide can be sufficiently increased, and the cellulose oxide can be easily defibrated when the nanocellulose is obtained.
• the effective chlorine concentration of the reaction solution is more preferably 15% by mass or more, further preferably 18% by mass or more, still more preferably 20. It is mass% or more. Further, from the viewpoint of suppressing excessive decomposition of cellulose during defibration, the effective chlorine concentration of the reaction solution is more preferably 40% by mass or less, still more preferably 38% by mass or less.
• the range of the effective chlorine concentration of the reaction solution can be appropriately combined with the above-mentioned lower limit and upper limit.
• the range of the effective chlorine concentration is more preferably 16 to 43% by mass, still more preferably 18 to 40% by mass.
• hypochlorous acid is a weak acid that exists as an aqueous solution
• hypochlorite is a compound in which hydrogen of hypochlorous acid is replaced with another cation.
• sodium hypochlorite which is a hypochlorite
• the concentration is measured not as the concentration of sodium hypochlorite but as the amount of effective chlorine in the solution. ..
• sodium hypochlorite since the oxidizing power of the divalent oxygen atom generated by the decomposition of sodium hypochlorite corresponds to the diatomic equivalent of monovalent chlorine, sodium hypochlorite is used.
• the sample is precisely weighed, water, potassium iodide and acetic acid are added and left to stand, and the free iodine solution is titrated with a sodium thiosulfate solution using an aqueous starch solution as an indicator to measure the effective chlorine concentration. do.
• the oxidation reaction of the cellulosic raw material with hypochlorous acid or a salt thereof should be carried out while adjusting the pH in the range of 5.0 to 14.0. Within this range, the oxidation reaction of the cellulosic raw material can be sufficiently promoted, and the amount of carboxy 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 6.0 or more, further preferably 7.0 or more, and even more preferably 8.0 or more.
• the upper limit of the pH of the reaction system is more preferably 13.5 or less, still more preferably 13.0 or less.
• the pH range of the reaction system is more preferably 7.0 to 14.0, and even more preferably 8.0 to 13.5.
• hypochlorite sodium hypochlorite is used as hypochlorous acid or a salt thereof.
• the reaction solution is preferably an aqueous solution of sodium hypochlorite.
• a method of adjusting the effective chlorine concentration of the sodium hypochlorite aqueous solution to the target concentration for example, target concentration: 6% by mass to 43% by mass
• sodium hypochlorite having a lower effective chlorine concentration than the target concentration is used.
• a method of concentrating an aqueous solution, a method of diluting an aqueous solution of sodium hypochlorite having an effective chlorine concentration higher than the target concentration, and a method of diluting sodium hypochlorite crystals (for example, sodium hypochlorite pentahydrate) as a solvent for example, sodium hypochlorite pentahydrate
• Examples thereof include a method of dissolving.
• adjusting the concentration of effective chlorine as an oxidizing agent by a method of diluting an aqueous solution of sodium hypochlorite or a method of dissolving crystals of sodium hypochlorite in a solvent has less self-decomposition (that is,). There is little decrease in the effective chlorine concentration), and it is preferable because it is easy to adjust the effective chlorine concentration.
• 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 them.
• the stirring method include a magnetic stirrer, a stirring rod, a stirring machine with a stirring blade (three-one motor), a homomixer, a disper type mixer, a homogenizer, and external circulation stirring.
• shear stirrers such as homomixers and homogenizers, stirrers with stirring blades, and stirrers with stirring blades are available because the oxidation reaction of the cellulosic raw material proceeds smoothly and the degree of polymerization of the oxidized cellulose can be easily adjusted to a predetermined value or less.
• a method using one or more of the disper type mixers is preferable, and a method using a stirrer with a stirring blade is particularly preferable.
• a stirrer with a stirrer blade a device equipped with a known stirrer blade such as a propeller blade, a paddle blade, and a turbine blade can be used as the stirrer.
• a stirrer with a stirring blade it is preferable to perform stirring at a rotation speed of 50 to 300 rpm.
• the reaction temperature in the oxidation reaction is preferably 15 ° C to 100 ° C, more preferably 20 ° C to 90 ° C.
• an alkaline agent for example, sodium hydroxide or the like
• an acid for example, hydrochloric acid or the like
• the reaction time of the oxidation reaction can be set according to the degree of progress of oxidation, but is preferably about 15 minutes to 50 hours.
• the pH of the reaction system is 10 or more, it is preferable to set the reaction temperature to 30 ° C. or higher and / or the reaction time to 30 minutes or longer.
• the fiber width and zeta potential of nanocellulose can be adjusted to desired values 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 increased, the oxidation of the cellulosic raw material to the surface of the cellulose microfibrils progresses, and the repulsion between the fibrils is caused by electrostatic repulsion or osmotic pressure. By strengthening, the average fiber width tends to be smaller.
• the zeta potential is set by setting one or more of the reaction time, reaction temperature, and stirring conditions of oxidation (for example, lengthening the reaction time) on the side where oxidation is further promoted (that is, the side where the degree of oxidation is increased). It tends to be expensive.
• the amount of carboxy group of the oxidized cellulose obtained by the above oxidation reaction is preferably 0.30 to 2.0 mmol / g.
• the amount of the carboxy group of the oxidized cellulose is 0.30 mmol / g or more, the defibration property of the oxidized cellulose can be sufficiently increased, and nanocellulose having a uniform fiber width can be obtained.
• the quality of the nanocellulose-containing slurry can be made uniform, and the viscosity stability, handleability and coatability of the slurry can be improved.
• the carboxy group amount of the oxidized cellulose is more preferably 0.35 mmol / g or more, further preferably 0.40 mmol / g or more, still more preferably 0.42 mmol / g or more, and further. More preferably, it is 0.50 mmol / g or more, more preferably 0.50 mmol / g or more, and even more preferably 0.55 mmol / g or more.
• the upper limit of the amount of carboxy group may be 1.5 mmol / g or less, 1.2 mmol / g or less, 1.0 mmol / g or less, 0.9 mmol / g or less. May be.
• the preferable range of the amount of carboxy group can be determined by appropriately combining the above-mentioned upper limit and lower limit.
• the amount of the carboxy group of the present oxidized cellulose is more preferably 0.35 to 2.0 mmol / g, further 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 over 0.50 to 1.2 mmol / g, and even more preferably 0.55 to 1.0 mmol / g. Is.
• the amount of carboxy group (mmol / g) in cellulose oxide was adjusted by adding a 0.1 M hydrochloric acid aqueous solution to an aqueous solution containing cellulose oxide to adjust the pH to 2.5, and then dropping a 0.05 N sodium hydroxide aqueous solution.
• the electric conductivity is measured until the pH reaches 11, and it can be calculated from the amount of sodium hydroxide (a) consumed in the neutralization step of a weak acid in which the change in the electric conductivity is moderate by using the following formula.
• Amount of carboxy group a (ml) x 0.05 / mass of cellulose oxide (g)
• a known isolation treatment such as filtration is performed, and further purification is performed as necessary to obtain an oxide of the cellulosic raw material by hypochlorous acid or a salt thereof.
• Oxidized cellulose can be obtained as.
• an acid is added to the solution containing the oxidized cellulose, for example, the pH is set to 4.0 or less, and the mixture is produced by oxidation.
• At least a part of the salt form of the carboxy group (-COO - X + : X + refers to a cation such as sodium or lithium) can be changed to a proton type (-COO- H +).
• a proton type (-COO- H +).
• a base was added in order to improve the handleability when the solution was used for the subsequent defibration treatment.
• the pH may be 6.0 or higher, and at least a part of the carboxy group may be in the salt type (-COO - X + : X + indicates a cation such as sodium or lithium).
• the solution containing cellulose oxide may be used as a composition containing cellulose oxide by substituting the solvent or the like.
• the pH is set to an alkaline condition of 10 or more, and at least a part of the carboxy group is a salt type (-COO - X + : X + indicates a cation such as sodium or lithium). be able to.
• Compounds having a modifying group capable of forming a covalent bond include, for example, alcohols, isocyanate compounds, and epoxy compounds.
• the oxidized cellulose includes a salt type, a proton type, and a modified type by a modifying group.
• the nanocellulose obtained from the present oxidized cellulose also includes the salt type, the proton type, and the modified type by a modifying group.
• a screw type mixer for example, a screw type mixer, a paddle mixer, a disper type mixer, a turbine type mixer, a homomixer under high speed rotation, a high pressure homogenizer, an ultrahigh pressure homogenizer, a double cylindrical homogenizer, and an ultrasonic homogenizer are used.
• Water flow counter-collision type disperser beater, disc type refiner, conical type refiner, double disc type refiner, grinder, single-screw or multi-screw kneader, rotation / revolution stirrer, vibration type stirrer, etc.
• the method can be mentioned.
• the method using an ultra-high pressure homogenizer can be preferably used in that nanocellulose with more advanced defibration can be efficiently produced.
• the pressure during the defibration treatment is preferably 100 MPa or more, more preferably 120 MPa or more, still more preferably 150 MPa or more.
• the number of defibration treatments is not particularly limited, but is preferably 2 or more, more preferably 3 or more, from the viewpoint of sufficiently advancing defibration.
• the above-mentioned oxidized cellulose can be sufficiently defibrated by mild stirring with a rotation / revolution stirrer, a vibration type stirrer or the like.
• the vibration type agitator include a vortex mixer (touch mixer). That is, according to the above-mentioned 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 in a state where cellulose oxide is mixed with a dispersion medium.
• the dispersion medium is not particularly limited and may be appropriately selected depending on the intended purpose. Specific examples of the dispersion medium include water, alcohols, ethers, ketones, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide and the like. As the solvent, one of these may be used alone, or two or more of them may be used in combination.
• alcohols include methanol, ethanol, isopropanol, isobutanol, sec-butyl alcohol, tert-butyl alcohol, methyl cellosolve, ethylene glycol, glycerin and the like.
• ethers include ethylene glycol dimethyl ether, 1,4-dioxane and tetrahydrofuran.
• ketone include acetone, methyl ethyl ketone and the like.
• an organic solvent as a dispersion medium during the defibration treatment, it becomes easy to isolate the oxidized cellulose and the nanocellulose obtained by defibrating the oxidized cellulose. Further, since nanocellulose dispersed in an organic solvent can be obtained, it becomes easy to mix with a resin that dissolves in the organic solvent, a resin raw material monomer, or the like.
• the nanocellulose dispersion obtained by dispersing the nanocellulose obtained by defibration in a dispersion medium of water and / or an organic solvent can be used for mixing with various components such as resin, rubber, and solid particles. ..
• the nanocellulose described above and the nanocellulose dispersion containing the same can be applied to various uses. Specifically, for example, it may be used as a reinforcing material mixed with various materials (for example, resin, fiber, rubber, etc.), or as a thickener or dispersant for various purposes (for example, food, cosmetics, etc.). It may be used in medical products, paints, inks, etc.). It is also possible to form a nanocellulose dispersion liquid and use it as various sheets or films.
• the field to which this nanocellulose and the nanocellulose dispersion containing it are applied is not particularly limited, and for example, various fields such as automobile parts, mechanical parts, electric appliances, electronic devices, cosmetics, medical products, building materials, daily necessities, stationery and the like.
• nanocellulose and a nanocellulose dispersion containing the same are used as an additive to a slurry containing inorganic particles such as pigments, the viscosity stability, handleability, and coating performance of the slurry should be improved. It is suitable in that it can be used.
• the present nanocellulose is a cellulose-based raw material obtained by oxidizing a cellulose-based raw material with hypochlorous acid or a salt thereof (cellulose-based raw material using hypochlorous acid or a salt thereof). It is also referred to as nanocellulose, which is an oxide of the above, does not contain an N-oxyl compound, and has an average fiber width of 1 nm or more and 5 nm or less. When the average fiber width of the nanocellulose is 1 to 5 nm, the zeta potential of the nanocellulose improves the dispersion stability of the nanocellulose and can improve the handling property when made into a slurry. It is preferably 25 mV or less, and more preferably -30 mV or less. As for the details of the method for producing the nanocellulose, the above description of the first embodiment can be referred to.
• the present nanocellulose is a cellulose-based raw material obtained by oxidizing a cellulose-based raw material with hypochlorous acid or a salt thereof (cellulose-based raw material using hypochlorous acid or a salt thereof). It is also called nanocellulose, which is an oxide of the above, does not contain an N-oxyl compound, and has an aspect ratio of 20 or more and 150 or less.
• the zeta potential of the nanocellulose is that the dispersion stability of the nanocellulose is improved and the handleability when made into a slurry can be improved. It is preferably 25 mV or less, and more preferably -30 mV or less.
• the above description of the first embodiment can be referred to.
• aqueous solution having a pH of 11.0.
• This sodium hypochlorite aqueous solution is heated to 30 ° C. by a constant temperature water bath while stirring at 200 rpm using a propeller type stirring blade with a stirrer (Three One Motor, BL600) manufactured by Shinto Kagaku Co., Ltd. 50 g of mechanically defibrated coniferous kraft pulp (carboxy group amount: 0.05 mmol / g) was added. After supplying the cellulosic raw material, keep the temperature at 30 ° C.
• 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) Precisely weigh 0.582 g of an aqueous solution of sodium hypochlorite pentahydrate crystals in pure water, add 50 ml of pure water, add 2 g of potassium iodide and 10 ml of acetic acid, immediately seal and place in the dark for 15 minutes. I left it. After standing for 15 minutes, the free iodine was titrated with a 0.1 mol / L sodium thiosulfate solution (indicator starch test solution), and the titration amount was 34.55 ml.
• the CNF aqueous dispersion B was obtained by treating under the same conditions as in Production Example 1 except that the reaction time in the oxidation reaction was 30 minutes.
• the CNF aqueous dispersion C was obtained by treating under the same conditions as in Production Example 1 except that the reaction time in the oxidation reaction was 120 minutes.
• the CNF aqueous dispersion D was obtained by treating under the same conditions as in Production Example 1 except that the reaction time in the oxidation reaction was set to 360 minutes.
• the CNF aqueous dispersion E was obtained by treating under the same conditions as in Production Example 1 except that the reaction time in the oxidation reaction was set to 480 minutes.
• the CNF aqueous dispersion F was obtained by treating under the same conditions as in Production Example 1 except that the reaction temperature in the oxidation reaction was changed from 30 ° C. to 40 ° C. and the reaction time was 120 minutes.
• the CNF aqueous dispersion G was obtained by treating under the same conditions as in Production Example 1 except that the reaction temperature in the oxidation reaction was changed from 30 ° C. to 50 ° C. and the reaction time was 120 minutes.
• the CNF aqueous dispersion K was obtained by treating under the same conditions as in Production Example 1 except that the reaction temperature in the oxidation reaction was changed from 30 ° C. to 15 ° C. and the reaction time was 120 minutes.
• the amount of carboxy group of the filtered product (cellulose oxide) after washing was measured and found to be 0.42 mmol / g.
• the ultrasonic oscillating part was immersed in the aqueous dispersion of cellulose oxide in a container, and the defibration was advanced by the ultrasonic waves oscillated from the ultrasonic oscillating part.
• aqueous sodium hypochlorite solution was heated to 30 ° C. in a constant temperature water bath while stirring with a stirrer, and then 0.35 g of the mechanically defibrated coniferous kraft pulp was added.
• the pH during the reaction was adjusted to 9.0 while keeping the temperature at 30 ° C. in the same constant temperature water bath while adding 48% by mass sodium hydroxide, and the mixture was stirred with a stirrer for 30 minutes. An oxidation reaction was carried out.
• the product was solid-liquid separated by suction filtration using a PTFE mesh filter having an opening of 0.1 ⁇ m, and the obtained filtered product was washed with pure water.
• the amount of carboxy group of the filtered product (cellulose oxide) after washing was measured and found to be 1.12 mmol / g.
• pure water was added to cellulose oxide to prepare a 5% dispersion, which was defibrated with an ultrasonic homogenizer under the same conditions as in Comparative Production Example 1 to obtain a CNF aqueous dispersion Q.
• the wet powder (water content 80% by mass, 20 g in terms of dry powder) was placed in a container, and then 60 L of an ozone / oxygen mixed gas having an ozone concentration of 200 g / m 3 was added and shaken at 25 ° C. for 2 minutes. After allowing to stand for 6 hours, ozone and the like in the container were removed, and then the oxidized cellulose was taken out and washed with pure water by suction filtration using a mesh filter made of PTFE with an opening of 0.1 ⁇ m. Pure water was added to the obtained cellulose oxide to prepare a 2% by mass dispersion, and sodium hydroxide was added to prepare a 0.3% by mass solution of sodium hydroxide.
• the amount of carboxy group of the filtered product (cellulose oxide) after washing was measured and found to be 1.55 mmol / g.
• Pure water was added to the obtained filtered product to prepare a 5% dispersion, and an aqueous sodium hydroxide solution was added to adjust the pH to 7.5, and the mixture was washed with water.
• the obtained dispersion was treated with an ultra-high pressure homogenizer "Starburst Lab HJP-25005" manufactured by Sugino Machine Limited under the conditions of 200 MPa and 10 passes to obtain a CNF aqueous dispersion T.
• the nitrogen component derived from the N-oxyl compound in the oxidized cellulose was measured as the amount of nitrogen under the same conditions as in Production Example 1, and the increase from the raw material pulp was calculated to be 5 ppm.
• Dispersion rate (solid content concentration after 4 weeks / solid content concentration immediately after dilution) ⁇ 100 ⁇ : Dispersion rate is less than 95% ⁇ : Dispersion rate is 90% or more and less than 95% ⁇ : Dispersion rate is 85% or more and less than 90% ⁇ : Dispersion rate is less than 85%
• the viscosity immediately after production (initial viscosity) and after standing for one week were measured, the viscosity change rate was calculated from the following formula, and the viscosity stability of the aqueous slurry was determined according to the following criteria.
• Viscosity change rate (%) (N2 / N1) x 100 (In the formula, N1 is the initial viscosity of the slurry, and N2 is the viscosity of the slurry after standing for one week after preparing the sample.) ⁇ : Viscosity change rate is less than 105% ⁇ : Viscosity change rate is 105% or more and less than 110% ⁇ : Viscosity change rate is 110% or more and less than 115% ⁇ : Viscosity change rate is 115% or more ⁇ 2 ° C).
• the initial viscosity of the slurry and the viscosity after standing for one week were determined by stirring with a spatula at a speed that does not allow bubbles to enter, and then using an E-type viscometer (TV-22) manufactured by Toki Sangyo Co., Ltd. at 25 ° C. and 100 rpm ( It was measured under the condition of shear rate 200s -1).
• Example 1-7 the slurry was evaluated as " ⁇ " or " ⁇ ” in all of the viscosity stability, handleability and coatability of the slurry, and the slurry characteristics were excellent. Moreover, from the results of Examples 1-1, 1-2 and 1-9 having the same zeta potential, the average fiber as compared with Example 1-9 in which the average fiber width of nanocellulose is 5.3 nm. Examples 1-1 and 1-2 having a width of 5 nm or less were found to exhibit better slurry properties. On the other hand, in Comparative Examples 1-1 to 1-4, the dispersion stability was evaluated as “x”, and the slurry characteristics were also inferior to those of Examples 1-1 to 1-9. In Comparative Example 1-5, although the dispersion stability was good, the slurry characteristics were all evaluated as “x”.
• Example 2-1 to 2-9 in which nanocellulose was produced by oxidation treatment with hypochlorite and Comparative Examples 2-1 and 2-2 are compared, the average fiber diameters are 5, respectively.
• Examples 2-1 to 2-9 having an average fiber diameter of 5.0 nm or less showed better slurry characteristics as compared with Comparative Examples 2-1 and 2-2 having a diameter of 3.3 nm and 5.2 nm. ..
• the zeta potential of nanocellulose is -30 mV as compared with Example 2-9 in which the zeta potential of nanocellulose is ⁇ 28.5 mV.
• the following Example 2-1 was found to exhibit better slurry properties.
• the aspect ratio was calculated from (average fiber length / average fiber width). The evaluation results are shown in Table 3.

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