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
• • 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
  • A61Q17/00—Barrier preparations; Preparations brought into direct contact with the skin for affording protection against external influences, e.g. sunlight, X-rays or other harmful rays, corrosive materials, bacteria or insect stings
  • A61Q17/005—Antimicrobial preparations
• • 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
• • 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
  • A61K2800/20—Chemical, physico-chemical or functional or structural properties of the composition as a whole
  • A61K2800/30—Characterized by the absence of a particular group of ingredients
• • 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
  • A61K2800/41—Particular ingredients further characterized by their size
  • A61K2800/413—Nanosized, i.e. having sizes below 100 nm

Definitions

• the present invention relates to oxidized cellulose, nanocellulose and dispersions thereof. More specifically, the present invention relates to an oxidized cellulose in which a cellulosic raw material is oxidized with an oxidizing agent and an oxidized cellulose dispersion containing the same, and a nanocellulose in which the oxidized cellulose is deflated and a nanocellulose dispersion containing the same.
• CNF cellulose nanofibers
• hypochlorous acid or a salt thereof is used as an oxidizing agent, and a cellulose-based raw material is oxidized to obtain oxidized cellulose under a high concentration condition where the effective chlorine concentration in the reaction system is 14 to 43% by mass. It has been disclosed.
• 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. Is disclosed to oxidize to obtain oxidized cellulose.
• 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
• Patent Document 1 and Patent Document 2 as a specific example of producing a nanocellulose material by refining cellulose oxide, an example in which a nanocellulose material is obtained through a defibration step by mechanical treatment using an ultrasonic homogenizer. Is disclosed. However, the above treatment has room for further improvement in terms of energy required for defibration. In the production of nanocellulose materials, from the viewpoint of production cost, oxidized cellulose having easy defibration ability that can be defibrated even under mild treatment conditions is required. Further, in order to stably produce finely divided cellulose fibers or to obtain a highly transparent nanocellulose material with less light scattering in a dispersion medium, the state before the nanocellulose material is defibrated. It is required that the defibration property of the oxidized cellulose is good.
• the present invention has been made in view of the above circumstances, and a main object thereof is to provide oxidized cellulose having excellent defibration properties.
• Cellulose oxide which is an oxide of a cellulosic raw material made of hypochlorous acid or a salt thereof, which does not substantially contain an N-oxyl compound and has a degree of polymerization of 600 or less.
• Cellulose oxide which is an oxide of a cellulosic raw material, is prepared by using an aqueous dispersion having a concentration of 0.1% by mass of the cellulose oxide at a revolution speed of 2000 rpm and a rotation speed of 800 rpm for 10 minutes.
• Oxide cellulose having a light transmittance of 60% or more in the nanocellulose aqueous dispersion obtained by the defibration treatment.
• Nanocellulose obtained by defibrating any of the oxidized celluloses of [1] to [6] and having an average fiber width of 1 to 200 nm. [8] Obtained by defibrating the cellulose oxide according to any one of [1] to [6] under the conditions of a revolution speed of 1200 to 2500 rpm and a rotation speed of 600 to 1000 rpm for 3 to 15 minutes with a rotation revolution stirrer. Nanocellulose. [9] A nanocellulose dispersion liquid in which the nanocellulose of [7] or [8] is dispersed in a dispersion medium.
• the present invention it is possible to obtain oxidized cellulose having excellent defibration properties.
• the oxidized cellulose of the present invention can be uniformly refined even when the defibration treatment is performed under mild conditions, and is excellent in easy defibration.
• the cellulose oxide of the present disclosure (hereinafter, also referred to as "main oxide cellulose”) is a fibrous cellulose obtained by oxidizing a cellulose-based raw material with hypochlorous acid or a salt thereof, and is before the defibration treatment.
• the present oxidized cellulose can also be said to be an oxide of a cellulosic raw material due to hypochlorous acid or a salt thereof.
• the main component of the plant is cellulose, and a bundle of cellulose molecules is called a cellulose microfibril.
• Cellulose in cellulosic raw materials is also contained in the form of cellulosic microfibrils. Since "cellulose oxide” is fibrous cellulose oxidized as described above, it is also referred to as "cellulose oxide fiber".
• Oxidized cellulose 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 oxidized cellulose does not contain any N-oxyl compound, or the content of the N-oxyl compound is the total amount of oxidized cellulose. 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.
• the N-oxyl compound is not substantially contained, it is possible to suppress the residue of the N-oxyl compound, which is concerned about the influence on the environment and the human body, in the oxidized cellulose.
• 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 the oxidized cellulose 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.
• a trace total nitrogen analyzer for example, manufactured by Mitsubishi Chemical Analytech Co., Ltd., device name: TN-2100H, etc.
• the degree of polymerization of the present oxidized cellulose is 600 or less.
• the degree of polymerization of the present oxidized cellulose exceeds 600, it tends to require a large amount of energy for defibration, and it tends to be impossible to exhibit sufficient defibration.
• the degree of polymerization of the present oxidized cellulose exceeds 600, the amount of oxidized cellulose which is insufficiently defibrated increases, so that when the finely divided nanocellulose is dispersed in the dispersion medium, light scattering and the like increase. , Transparency may decrease.
• the size of the obtained nanocellulose varies, and the quality tends to be non-uniform.
• the viscosity of the slurry containing nanocellulose together with the solid particles may become unstable, and the handleability and coatability of the slurry may deteriorate.
• the lower limit of the degree of polymerization of the present oxidized cellulose is not particularly set.
• the degree of polymerization of this oxidized cellulose is less than 50, the proportion of particulate cellulose rather than fibrous is increased, the quality of the slurry becomes non-uniform, the viscosity becomes unstable, and the characteristics of nanocellulose are characteristic. It becomes difficult to obtain the viscosity property, which is one of the above.
• the degree of polymerization of the present oxidized cellulose is preferably 50 to 600.
• the degree of polymerization of the present oxidized cellulose is more preferably 580 or less, further preferably 560 or less, still more preferably 550 or less, still more preferably 500 or less, still more preferably 450 or less, still more. It is preferably 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, still more preferably, from the viewpoint of improving the 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.
• the preferable 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 present oxidized 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, still more preferably 80. It is ⁇ 500, more preferably 80 ⁇ 450, and particularly preferably 80 ⁇ 400.
• the degree of polymerization of cellulose oxide can be adjusted by changing the reaction time, reaction temperature, pH, and the effective chlorine concentration of hypochlorous acid or a salt thereof during the oxidation reaction. Specifically, since the degree of polymerization tends to decrease as the degree of oxidation increases, for example, a method of increasing the reaction time and / or the reaction temperature of oxidation can be mentioned in order to reduce the degree of polymerization. As another method, the degree of polymerization of cellulose oxide can be adjusted by the stirring conditions of the reaction system at the time of 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 proceeds smoothly and the degree of polymerization tends to decrease.
• the degree of polymerization of cellulose oxide tends to vary depending on the selection of the 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 cellulose oxide is the average degree of polymerization (viscosity average degree of polymerization) measured by the viscosity method. For details, follow the method described in Examples described later.
• the amount of carboxy group of the present oxidized cellulose is preferably 0.30 to 2.0 mmol / g.
• the amount of the carboxy group is 0.30 mmol / g or more, sufficient friability can be imparted to the oxidized cellulose.
• a nanocellulose-containing slurry with uniform quality can be obtained even when the defibration treatment is performed under mild conditions, and the viscosity stability, handleability and coatability of the slurry can be improved. can.
• the carboxy group amount of the present 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. It is even more preferably 0.50 mmol / g or more, even 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 is more preferably 1.5 mmol / g or less, still more preferably 1.2 mmol / g, still more preferably 1.0 mmol / g or less, and even more preferably 0. It is 9 mmol / g.
• 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 is adjusted to pH 2.5 by adding a 0.1 M hydrochloric acid aqueous solution to an aqueous solution of cellulose oxide mixed with water, and then a 0.05 N sodium hydroxide aqueous solution is added dropwise. Then, the electric conductivity was measured until the pH reached 11.0, and the amount of sodium hydroxide (a) consumed in the neutralization step of the weak acid in which the change in the electric conductivity was moderate was calculated using the following formula. The value. For details, follow the method described in Examples described later.
• the present oxidized cellulose is produced by, for example, oxidizing a cellulose-based raw material under the condition that the effective chlorine concentration of hypochlorous acid or a salt thereof in the reaction system is relatively high (for example, 14% by mass to 43% by mass). Obtainable.
• the present oxidized cellulose 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 oxidized cellulose is not oxidized and remains as a hydroxyl group.
• the position of the carboxy group in the glucopyranose ring of cellulose oxide 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 oxidized cellulose of the present disclosure is excellent in defibration.
• the present oxidized cellulose can be uniformly refined even when the defibration treatment is performed under mild conditions, and is excellent in defibration.
• the finely divided cellulose oxide is mixed with inorganic particles such as a pigment to form a slurry, the slurry viscosity is stable over time and is excellent in handleability and coatability.
• it does not contain an N-oxyl compound it is possible to reduce the influence on the environment and the like.
• the present oxidized cellulose can be produced by a method including a step of oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof.
• 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.
• cellulose-based raw material 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 the present oxidized cellulose by oxidizing the cellulosic raw material include a method of mixing the cellulosic raw material with a reaction solution containing hypochlorous acid or a salt thereof.
• the reaction solution preferably contains water as a solvent 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.
• 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.
• the method for producing the present oxidized cellulose may further include a step of mixing the obtained oxidized cellulose with a compound having a modifying group.
• the compound having a modifying group is not particularly limited as long as it is a compound having a modifying group capable of forming an ionic bond or a covalent bond with a carboxy group or a hydroxyl group of cellulose oxide.
• Examples of the compound having a modifying group capable of forming an ionic bond include a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium compound, and a phosphonium compound.
• Compounds having a modifying group capable of forming a covalent bond include, for example, alcohols, isocyanate compounds, and epoxy compounds.
• the present 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.
• the present oxidized cellulose may be used as a mixture with a dispersion medium. That is, one of the present inventions is a cellulose oxide dispersion liquid in which the present cellulose oxide is dispersed in a dispersion medium. Examples of the dispersion medium include the same dispersion media as those described later.
• nanocellulose of the present disclosure (hereinafter, also referred to as "nanocellulose”) can be obtained by defibrating and nanonizing the oxidized cellulose obtained by oxidizing the cellulose-based raw material with an oxidizing agent. That is, the present nanocellulose can be produced by a method including a step of oxidizing a cellulosic raw material with hypochlorous acid or a salt thereof and a step of defibrating the oxidized cellulose obtained by the step. The oxidation step is as described above.
• nanocellulose is fibrous cellulose obtained by refining oxidized fibrous cellulose, it is also referred to as "fine cellulose fiber”.
• nanocellulose is a general term for nano-sized cellulose, and includes cellulose nanofibers, cellulose nanocrystals, and the like.
• 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.
• a method using an ultra-high pressure homogenizer may be 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.
• this oxidized cellulose is excellent in defibration, it can be sufficiently defibrated even when mild stirring by, for example, a rotation / revolution stirrer or a vibration type stirrer is applied as a defibration method, and uniformed nanocellulose. It is preferable in that the above can be obtained.
• the rotation / revolution agitator is a device that mixes the materials in the container by rotating and revolving the container into which the material is charged. According to the rotation / revolution stirrer, stirring is performed without using a stirring blade, so that milder stirring can be realized.
• the revolution speed and the rotation speed at the time of stirring by the rotation / revolution stirrer can be appropriately set. For example, the revolution speed can be set to 400 to 3000 rpm and the rotation speed can be set to 200 to 1500 rpm.
• the defibration process is performed under the conditions of stirring at a revolution speed of 1200 to 2500 rpm and a rotation speed of 600 to 1000 rpm for 3 to 15 minutes from the viewpoint of ensuring gentle quality stirring while achieving mild stirring. Is preferable.
• the revolution speed is more preferably 1500 to 2300 rpm, and the rotation speed is more preferably 700 to 950 rpm.
• the concentration of the aqueous dispersion of cellulose oxide as a material may be appropriately adjusted, but is, for example, 0.01 to 1.0% by mass, preferably 0. .1 to 0.5% by mass.
• vibration type agitator examples include a vortex mixer (touch mixer).
• a vortex mixer stirring is performed by forming a vortex in the liquid material in the container.
• agitation is performed without using a stirring blade, so that milder agitation can be realized.
• mild agitation can be realized by simple equipment, which is excellent in terms of production equipment and production cost.
• the rotation speed of the vortex mixer is, for example, 600 to 3000 rpm, and it is preferable to perform the defibration treatment under the condition of stirring for 3 to 15 minutes.
• the concentration of the aqueous dispersion of cellulose oxide as a material may be appropriately adjusted, but is, for example, 0.01 to 1.0% by mass, preferably 0.1. ⁇ 0.5% by mass.
• the defibration treatment is preferably carried out in a state where the present oxidized cellulose 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 average fiber width of the nanocellulose is preferably 1 to 200 nm.
• the present oxidized cellulose is suitable in that it is possible to obtain nanocellulose having an average fiber width of 1 to 20 nm, preferably 1 to 10 nm, more preferably 1 to 5 nm by defibration treatment. Is.
• the average fiber width of the nanocellulose is sufficiently small as 1 to 5 nm, the viscosity of the slurry containing the nanocellulose is stable, and the handleability and coatability are good.
• the average fiber width of the nanocellulose is more preferably 4.8 nm or less, further preferably 4.5 nm or less, still more preferably 4.2 nm or less.
• the lower limit of the average fiber width is not set in particular.
• the average fiber width is preferably 1 nm or more, more preferably 1.5 nm or more.
• the average fiber length of the nanocellulose is preferably 100 to 2000 nm.
• the average fiber length is more preferably 100 to 1000 nm, still more preferably 100 to 500 nm, and even more preferably 100 to 400 nm.
• 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 200.
• the aspect ratio is more preferably 30 or more, still more preferably 40 or more.
• the aspect ratio is more preferably 180 or less, still more preferably 150 or less.
• nanocellulose and water were mixed so that the concentration of nanocellulose was approximately 1 to 10 ppm, and a sufficiently diluted cellulose aqueous dispersion was naturally dried on a mica substrate.
• the shape of nanocellulose was observed using a scanning probe microscope, and an arbitrary number of fibers were randomly selected from the obtained images.
• 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.
• this cellulose oxide can be obtained by defibrating a water dispersion having a concentration of 0.1% by mass of the cellulose oxide in a rotation / revolution stirrer at a revolution speed of 2000 rpm and a rotation speed of 800 rpm for 10 minutes. It is preferable that the light transmittance of the nanocellulose aqueous dispersion to be obtained shows a value of 60% or more.
• the light transmittance of this nanocellulose aqueous dispersion is more preferably 70% or more, further preferably 75% or more, still more preferably 80% or more.
• the light transmittance is a value measured by a spectrophotometer at a wavelength of 660 nm.
• the present oxidized cellulose is a light transmittance of the nanocellulose aqueous dispersion obtained by defibrating the water dispersion having a concentration of 0.1% by mass of the oxidized cellulose with a vortex mixer at a rotation speed of 3000 rpm for 10 minutes. It is preferable that the rate shows a value of 60% or more.
• the light transmittance of this nanocellulose aqueous dispersion is more preferably 70% or more, further preferably 75% or more, still more preferably 80% or more.
• the reason why the oxidized cellulose of the present disclosure is excellent in defibration (particularly easy defibration) and gives a high quality slurry is not clear, but the following can be generally considered.
• the defibration proceeds by breaking the hydrogen bonds between the cellulose microfibrils.
• the degree of polymerization of microfibrils decreases (that is, the cellulose molecular chain is shortened) as the oxidation progresses.
• This decrease in the degree of polymerization is such that when oxidized with a relatively high concentration of hypochlorous acid or a salt thereof, the degree of polymerization is likely to decrease as the degree of oxidation increases, as compared with the case of, for example, the TEMPO oxidation method. .. Therefore, in the present embodiment, the number of hydrogen bonds to be cleaved by defibration in each microfibril by oxidation treatment is small, and the amount of carboxy group increases as the oxidation progresses, so that the microfibrils are separated from each other. It is considered that the repulsive force of the hydrogen oxide was strengthened and the defibration property of the oxidized cellulose was improved. Further, it is considered that the improved defibability of the oxidized cellulose made it possible to obtain nanocellulose capable of improving the viscosity stability, handleability and coatability of the slurry.
• oxidized cellulose obtained by oxidizing a cellulosic raw material with an oxidizing agent.
• This oxidized cellulose can also be referred to as cellulose oxide which is an oxide of a cellulosic raw material.
• the cellulose oxide of the present embodiment is nano obtained by defibrating a 0.1% by mass water dispersion of the cellulose oxide with a rotation revolution stirring machine at a revolution speed of 2000 rpm and a rotation speed of 800 rpm for 10 minutes.
• the light transmittance of the cellulose aqueous dispersion is 60% or more.
• the present cellulose oxide is subjected to defibration treatment of the 0.1% by mass water dispersion of the cellulose oxide in a vortex mixer at a rotation speed of 3000 rpm for 10 minutes.
• the light transmittance of the nanocellulose aqueous dispersion obtained by the above is 60% or more.
• nanocellulose having a fiber width of about 1 to 5 nm can be obtained. Since the obtained nanocellulose has a sufficiently small fiber width, when it is dispersed in a dispersion medium, the cellulose fibers are less light scattered and exhibit high light transmittance. Therefore, it can be effectively used in applications that require transparency. Further, the nanocellulose obtained by defibrating the above-mentioned other forms of oxidized cellulose aims to stabilize the viscosity of the slurry when it is made into a nanocellulose-containing slurry even if the defibration treatment is performed under mild conditions. At the same time, the handleability and coatability of the slurry can be improved.
• hypochlorous acid or salts thereof examples include halogens, hypochlorous acid or salts thereof, peroxides and the like.
• hypochlorous acid or a salt thereof is preferable because it is possible to obtain homogenized nanocellulose, and it has a low environmental load and is inexpensive.
• Hypochlorous acid or its salt is as described above.
• 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.
• 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 oxidation reaction was carried out by stirring at 200 rpm using a propeller type stirring blade. After completion of the reaction, the product was solid-liquid separated by suction filtration using a PTFE membrane filter having an opening of 0.1 ⁇ m to obtain oxidized cellulose A. The obtained cellulose oxide A was washed with pure water, and the amount of carboxy group in the filtered product (cellulose oxide A) after washing was measured and found to be 0.45 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) 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.
• Oxidized cellulose B and CNF aqueous dispersion B were obtained by treating under the same conditions as in Production Example 1 except that the reaction time in the oxidation reaction was 120 minutes.
• Oxidized cellulose C and CNF water were treated under the same conditions as in Production Example 1 except that the reaction time in the oxidation reaction was set to 120 minutes and the cellulose-based raw material was changed to powdered cellulose (VP-1) manufactured by TDI. Dispersion C was obtained.
• Oxidized cellulose E and CNF aqueous dispersion E were obtained by treating under the same conditions as in Production Example 1 except that the oxidation reaction time was set to 240 minutes.
• Oxidized cellulose F and CNF aqueous dispersion F were obtained by treating under the same conditions as in Production Example 1 except that the oxidation reaction time was set to 360 minutes.
• Oxidized cellulose G and CNF aqueous dispersion G were obtained by treating under the same conditions as in Production Example 1 except that the oxidation reaction temperature was set to 50 ° C.
• Oxidized cellulose H and CNF aqueous dispersion H were obtained by treating under the same conditions as in Production Example 1 except that the oxidation reaction time was set to 480 minutes.
• the solid 13 C-NMR of the sample left at 23 ° C. and 50% RH for 24 hours or more was measured. It was confirmed that the hydroxyl group at the 3-position was oxidized to have a structure in which a carboxy group was introduced.
• the measurement conditions for solid 13 C-NMR are shown below.
• the 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.
• 48% by mass of sodium hydroxide was added to maintain pH 11.0 while keeping the temperature at 30 ° C. in the same constant temperature water tank, and the mixture was stirred with a stirrer for 30 minutes.
• the product was solid-liquid separated by suction filtration using a PTFE membrane filter having an opening of 0.1 ⁇ m to obtain oxidized cellulose P.
• the carboxy group amount was measured after washing the obtained filtered product (cellulose oxide P) with pure water, it was 0.42 mmol / g, and the filtered product amount was 0.31 g.
• the obtained oxidized cellulose P is dispersed in pure water to prepare a 0.1% dispersion liquid, and a revolution speed of 2000 rpm is prepared in a mix mode using a rotation / revolution mixer "Awatori Rentaro ARE-310" manufactured by Shinky.
• the defibration treatment was carried out for 10 minutes under the condition of a rotation speed of 800 rpm to obtain a CNF aqueous dispersion P.
• 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 to obtain cellulose oxide Q.
• 0.12 g of the obtained filtered product was washed with pure water.
• the amount of carboxy group in the filtered product (cellulose Q oxide) after washing was measured and found to be 1.12 mmol / g.
• pure water was added to cellulose oxide Q to prepare a 0.1% dispersion liquid, which was subjected to defibration treatment 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 standing for 6 hours, ozone and the like in the container were removed, and then cellulose oxide (cellulose oxide R) 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 R to prepare a 2% by mass dispersion, and sodium hydroxide was added to prepare a 0.3% by mass solution of sodium hydroxide.
• the product obtained above was added to a 1M aqueous acetic acid solution containing sodium chlorite, and the mixture was stirred at 25 ° C. for 48 hours under the same stirring conditions as above. After completion of the reaction, the product was solid-liquid separated by suction filtration using a PTFE membrane filter having an opening of 0.1 ⁇ m, and washed with pure water. Pure water was added to the obtained oxidized cellulose S to prepare a 0.1% dispersion, which was defibrated under the same conditions as in Comparative Production Example 1 to obtain a CNF aqueous dispersion S.
• the amount of carboxy group was measured.
• the amount of carboxy group was 1.55 mmol / g, and the amount of substance on filtration was about 1.0 g.
• Pure water was added to the obtained oxidized cellulose T to prepare a 0.1% dispersion, which was defibrated under the same conditions as in Comparative Production Example 1 to obtain a CNF aqueous dispersion T.
• the nitrogen component derived from the N-oxyl compound in the oxidized cellulose T 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.
• the flow time of the blank solution and the flow time of the cellulose solution were measured at 25 ° C. with a capillary viscometer. From the flow time of the blank solution (t0), the flow time of the cellulose solution (t), and the concentration of oxidized cellulose (c [g / ml]), the relative viscosity ( ⁇ r ) and the specific viscosity ( ⁇ sp ) are as shown in the following equations. The intrinsic viscosity ([ ⁇ ]) was sequentially obtained, and the degree of polymerization (DP) of cellulose oxide was calculated from the viscosity measurement formula.
• ⁇ Defibering method B Each of the cellulose oxides A to H and P to T obtained above was mixed with water to prepare an aqueous dispersion of cellulose oxide having a solid content concentration of 0.1%. This aqueous cellulose oxide dispersion was taken in a glass container having a capacity of 13.5 ml and treated with a vortex mixer (VTX-3000L) manufactured by LMS for 10 minutes to obtain a CNF aqueous dispersion. The solid content concentration of each CNF aqueous dispersion was 0.1% by mass.
• Each CNF aqueous dispersion was placed in a quartz cell having a thickness of 10 mm, and the light transmittance at a wavelength of 660 nm was measured by a spectrophotometer (JASCO V-550). Each measured value was evaluated in four stages in the same manner as in the defibration method A.
• 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 evaluation 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).
• the cellulose microfibrils were easily separated from each other even by mild stirring with a rotation revolution mixer or a vortex mixer, and showed high light transmittance when used as a CNF aqueous dispersion. Further, by the defibration treatment with a rotation / revolution mixer, fine cellulose fibers having an average fiber width of 5 nm or less could be obtained. Further, the slurries of Examples 1-1 to 1-8 had a good balance of viscosity stability, handleability and coatability. In particular, in Examples 1-1 to 1-7 in which the degree of polymerization was on the order of three digits, all the evaluations of viscosity stability, handleability and coatability were " ⁇ " or " ⁇ ", and the slurry characteristics. Was excellent.
• Comparative Examples 1-1 and 1-2 having a degree of polymerization of 730 and 650 the cellulose microfibrils are difficult to be separated from each other by mild stirring with a rotation / revolution mixer or a vortex mixer, and the fragility is “x”. It was an evaluation of. In addition, all the slurry characteristics were evaluated as " ⁇ ", which was inferior to Examples 1-1 to 1-8. Even in Comparative Examples 1-3 to 1-5 having different oxidation methods, the evaluation of the easy defibration property and the slurry characteristics was inferior to that of the Examples.
• This aqueous cellulose oxide dispersion was treated with a stirrer, the obtained CNF aqueous dispersion was placed in a quartz cell having a thickness of 10 mm, and the light transmittance at a wavelength of 660 nm was measured with a spectrophotometer (JASCO V-550).
• a spectrophotometer JASCO V-550
• the CNF aqueous dispersion obtained by defibrating the 0.5% aqueous cellulose oxide dispersion the CNF aqueous dispersion was diluted with pure water to 0.1% and the light transmittance was measured.
• a stirrer a rotation / revolution mixer "Awatori Rentaro ARE-310" manufactured by Shinky Co., Ltd.
• Light transmittance is 80% or more
• Light transmittance is 70% or more and less than 80%
• Light transmittance is 60% or more and less than 70%
• Light transmittance is less than 60%
• the cellulose oxides of Examples 2-1 to 2-11 showed high light transmittance when the CNF aqueous dispersion was used, because the cellulose microfibrils were easily separated from each other even by mild stirring with a rotation / revolution mixer. Further, even when the concentration of cellulose oxide during the defibration treatment is increased from 0.1% to 0.5%, the light transmittance of the CNF aqueous dispersion is sufficiently high, and the viscosity stability of the aqueous slurry is further improved. The handling and coating properties were well balanced.
• Comparative Examples 2-1 to 2-5 the light transmittance of the CNF aqueous dispersion was as low as 50% when the defibrating was performed by gentle stirring with a rotation / revolution mixer. Indicated. Further, Comparative Examples 2-1 to 2-5 were also inferior to Examples 2-1 to 2-11 in terms of slurry characteristics.

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