Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
  • C08J3/16—Powdering or granulating by coagulating dispersions
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
• • 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

Definitions

• the present invention relates to inorganic inclusion cellulose particles and a method for producing the same.
• This application claims priority based on Japanese Patent Application No. 2020-083983 filed in Japan on May 12, 2020, the contents of which are incorporated herein by reference.
• particles such as acrylic beads, polystyrene beads, and polyurethane beads have been used in various products such as paints, plastics, adhesives, and cosmetics.
• the issue of microplastics in the marine environment has been widely addressed, and the need for micrometer-scale cellulose particles made from natural products is increasing.
• Patent Document 1 describes the following methods (1) and (2).
• An object of the present invention is to provide an inorganic substance-encapsulating cellulose particles having excellent low hygroscopicity and a method for producing the same.
• the present invention has the following aspects.
• Inorganic-encapsulating cellulose particles in which an inorganic substance is encapsulated in cellulose-containing cellulose particles, wherein the mass ratio (inorganic substance / cellulose) between the inorganic substance and the cellulose is 2/8 to 8/2, and the average particle diameter.
• the inorganic substance is preferably at least one compound selected from the group consisting of calcium carbonate, calcium stearate, barium sulfate, talc, mica, kaolin, silica, and alumina, and more preferably calcium carbonate and calcium stearate.
• Silica and at least one compound selected from the group consisting of talc, more preferably at least one compound selected from the group consisting of calcium carbonate and calcium stearate.
• [8] The method for producing cellulose particles containing an inorganic substance according to any one of [1] to [7], wherein a cellulose acetate solution in which cellulose acetate is dissolved in an organic solvent and the inorganic substance are used, and the inorganic substance and the cellulose are used.
• a resin mixed solution mixed so that the mass ratio (inorganic substance / cellulose) is 2/8 to 8/2 is suspended in water, and a suspension in which cellulose acetate particles containing the inorganic substance are dispersed in water is prepared.
• a method for producing an inorganic substance-encapsulated cellulose particle wherein the organic solvent is removed from the suspension and the cellulose acetate particles are sacrificed to obtain the inorganic substance-encapsulated cellulose particle in which the inorganic substance is encapsulated in the cellulose particle.
• the cellulose acetate solution and the inorganic substance so that the ratio of the inorganic substance is preferably 15 to 240 parts by mass, more preferably 40 to 240 parts by mass, and further preferably 90 to 240 parts by mass with respect to 100 parts by mass of cellulose acetate.
• the method for producing inorganic-encapsulated cellulose particles according to any one of [8] to [12] above, wherein the organic solvent is a solvent having a co-boiling point with water at 1013 hPa of 100 ° C. or lower.
• the organic solvent is preferably an aromatic compound such as toluene or benzene; an ester compound such as methyl acetate, ethyl acetate or butyl acetate; a ketone compound such as acetone or methyl ethyl ketone; and n-heptane, n-hexane or n.
• the inorganic substance-encapsulating cellulose particles of the present invention are those in which an inorganic substance is encapsulated in cellulose particles containing cellulose. That is, the inorganic substance-encapsulating cellulose particles include cellulose and an inorganic substance. Inorganic-encapsulating cellulose particles may further contain other components other than cellulose and inorganic substances as long as the effects of the present invention are not impaired. Examples of other components include trace amounts of cellulose acetate, suspension stabilizers, surfactants, water, organic fillers, pigments (excluding inorganic substances), medicinal materials, etc., but other components include these. Not limited to examples.
• encapsulating an inorganic substance means that the inorganic substance is contained inside the cellulose particles.
• the inorganic substance may be entirely contained in the cellulose particles, or a part of the inorganic substance may be exposed on the surface of the cellulose particles.
• the state of "encapsulating an inorganic substance” can be confirmed by a method of visually observing the particle cross section or the particle surface with an optical microscope, a method of analyzing an image with a scanning electron microscope, or the like.
• the "inorganic substance-encapsulating cellulose particle” is a particle having a form in which one inorganic particle is coated with cellulose even if a plurality of inorganic particles are contained in one cellulose particle. It doesn't matter.
• the amount of the cellulose particles containing no inorganic substance is preferably 8% or less, more preferably 5% or less.
• the refractive index of the inorganic substance is preferably 1.43 to 2.00, more preferably 1.43 to 1.80, further preferably 1.45 to 1.75, and particularly preferably 1.45 to 1.70.
• the refractive index of the inorganic substance is a value measured by irradiating the inorganic substance with sodium D-rays in an atmosphere of 25 ° C. using an Abbe refractive index meter.
• inorganic substances having a refractive index within the above range include calcium carbonate (refractive index: 1.50 to 1.69), calcium stearate (refractive index: 1.47), barium sulfate (refractive index: 1.64), and the like. Talk (refractive index: 1.54 to 1.59), mica (refractive index: 1.53), kaolin (refractive index: 1.64), silica (refractive index: 1.44 to 1.50), alumina ( Refractive index: 1.76) and the like.
• calcium carbonate, calcium stearate, silica, and talc are preferable, and calcium carbonate and calcium stearate are more preferable, from the viewpoint of easily maintaining the transparency of the cellulose particles contained in the inorganic substance.
• the inorganic substance one kind may be used alone, or two or more kinds may be used in combination.
• the particle size of the inorganic substance is not particularly limited as long as the average particle size of the cellulose particles contained in the inorganic substance is within the range described later.
• the inorganic substance is preferably surface-treated with at least one of the fatty acid and the silane compound (hereinafter, the fatty acid and the silane compound are collectively referred to as "surface treatment agent"). If the inorganic substance is surface-treated with a surface treatment agent, the hydrophobicity of the surface of the inorganic substance is enhanced, and inclusion in the cellulose acetate particles described later becomes easy.
• surface-treated means that the surface of the inorganic substance is covered with the surface-treating agent.
• the surface treatment agent examples include fatty acids and silane compounds, and fatty acids are preferable from the viewpoint of facilitating the inclusion of inorganic substances in the cellulose acetate particles.
• the surface treatment agent one type may be used alone, or two or more types may be used in combination.
• the amount of the surface treatment agent is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, and further preferably 1 to 3 parts by mass with respect to 100 parts by mass of the inorganic substance. ..
• the fatty acid examples include saturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and isostearic acid or salts thereof; unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid and lysynolic acid or The salt and the like can be mentioned.
• Examples of salts of saturated fatty acids and unsaturated fatty acids include alkali metal salts such as potassium and sodium, and ammonium salts. Among these, saturated fatty acids are preferable, and stearic acid is more preferable, from the viewpoint of facilitating the inclusion of inorganic substances in the cellulose acetate particles.
• One type of fatty acid may be used alone, or two or more types may be used in combination.
• silane compound examples include vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3 -(Meta) acryloyl group-containing silane coupling agent such as (meth) acryloxylpropylmethyldimethoxysilane, 3- (meth) acryloxylpropylmethyldiethoxysilane; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxy.
• vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane
• 3- (meth) acryloxypropyltrimethoxysilane 3- (meth) acryloxypropyltriethoxysilane
• 3 -(Meta) acryloyl group-containing silane coupling agent such as (
• Silane N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N- Amino group-containing silane coupling agent such as phenyl-3-aminopropyltriethoxysilane; 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, Examples thereof include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltriethoxysilane and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane.
• One type of silane compound may be used alone, or two or more types may be used in combination.
• the mass ratio of the inorganic substance to cellulose is 2/8 to 8/2, preferably 4/6 to 8/2, and more preferably 6/4 to 8/2.
• the mass ratio is at least the above lower limit value, the low hygroscopicity of the cellulose particles contained in the inorganic substance is enhanced.
• the mass ratio is at least the above lower limit value, it is easy to suitably maintain the performance of the cellulose particles (however, excluding hygroscopicity).
• Inorganic inclusion cellulose particles are usually spherical.
• the average particle size of the inorganic substance-encapsulated cellulose particles is 1 to 300 ⁇ m, preferably 1 to 150 ⁇ m, and more preferably 1 to 100 ⁇ m. When the average particle size of the inorganic substance-encapsulated cellulose particles is within the above range, the production of spherical inorganic-encapsulated cellulose particles tends to be easy.
• the average particle size of the inorganic inclusion cellulose particles is a volume-based average particle size (volume average particle size) measured using a laser diffraction type particle size distribution meter. The average particle size is the median size (d50).
• the hygroscopicity is preferably 3% or less, more preferably 2.5% or less, further preferably 2% or less, and particularly preferably 1.5% or less.
• the hygroscopicity of the cellulose particles contained in the inorganic substance can be determined as follows. After drying the inorganic substance-encapsulated cellulose particles (for example, 1 g or more) at 110 ° C. for 15 hours in advance, the particles are left in an atmosphere with a humidity of 100% and a temperature of 85 ° C.
• the inorganic substance-encapsulated cellulose particles are collected, and the mass (W 11 ) of the inorganic-encapsulated cellulose particles after moisture absorption is measured. After measuring the mass, the inorganic substance-encapsulated cellulose particles were dried at 110 ° C. for 2 hours, and the mass (W 12 ) of the dried inorganic substance-encapsulated cellulose particles was measured. Find N 1 ). Similarly, at the time when 168 hours have passed from the start of leaving, the inorganic substance-encapsulated cellulose particles are collected, and the mass (W 21 ) of the inorganic-encapsulated cellulose particles after moisture absorption is measured.
• N 1 (mass%) W 12 / W 11 ⁇ 100 ⁇ ⁇ ⁇ (i)
• N 2 (mass%) W 22 / W 21 ⁇ 100 ⁇ ⁇ ⁇ (ii)
• Hygroscopicity (%) (N 1- N 2 ) / N 2 x 100 ... (iii)
• the mass ratio (inorganic substance / cellulose) of the cellulose acetate solution in which cellulose acetate is dissolved in an organic solvent and the inorganic substance is 2/8 to 8/2.
• the resin mixture was suspended in water so as to prepare a suspension in which cellulose acetate particles containing inorganic substances were dispersed in water, the organic solvent was removed from the suspension, and the cellulose acetate particles were sacrificed.
• the cellulose particles are made into the inorganic substance-encapsulating cellulose particles in which the inorganic substance is contained.
• water may be further removed by solid-liquid separation to dry the inorganic substance-encapsulated cellulose particles.
• the method for producing the inorganic substance-encapsulated cellulose particles of the present embodiment includes the following steps (a) to (d), and in addition to the steps (a) to (d), the following steps (e) are further added. It can be said that it may have.
• the mass ratio of the inorganic substance to the cellulose is 2/8 to 8/2, preferably the mass ratio is 4/6 to 8/2.
• Mix the cellulose acetate solution and the inorganic substance so that the mass ratio is 6/4 to 8/2.
• the ratio of the inorganic substance is more preferably 40 to 240 parts by mass, still more preferably 90 to 240 parts by mass with respect to 100 parts by mass of cellulose acetate.
• step (b) the resin mixed solution obtained in step (a) is suspended in water to prepare a suspension in which cellulose acetate particles containing an inorganic substance are dispersed in water.
• cellulose acetate is dissolved in an organic solvent, so when the resin mixed solution is suspended in water, the resin mixed solution becomes oil and disperses in water to form oil droplets and contain inorganic substances.
• a suspension in which the resulting cellulose acetate particles are dispersed in water is obtained.
• cellulose acetate the degree of substitution of the acetyl group, the vinegarization rate and the like are not particularly limited.
• examples of cellulose acetate include monoacetyl cellulose, diacetyl cellulose, triacetyl cellulose and the like.
• the viscosity of the cellulose acetate solution is not particularly limited, but is preferably 500 to 300,000 mPa ⁇ s, and more preferably 2000 to 100,000 mPa ⁇ s.
• the viscosity is a value measured under the condition of a temperature of 25 ° C. using a BL type rotational viscometer (for example, "RB-85L" manufactured by Toki Sangyo Co., Ltd.).
• Cellulose acetate may be used alone or in combination of two or more.
• the organic solvent used in the step (a) is not particularly limited as long as it is a compound capable of dissolving cellulose acetate. However, as the organic solvent, one having low solubility in water is preferable.
• the organic solvent preferably has a co-boiling point with water at 1013 hPa of 100 ° C. or lower. Examples of the organic solvent having a co-boiling point with water at 1013 hPa of 100 ° C. or lower include aromatic compounds such as toluene and benzene; ester compounds such as methyl acetate, ethyl acetate and butyl acetate; and ketone compounds such as acetone and methyl ethyl ketone; n.
• -Saturated aliphatic hydrocarbons such as heptane, n-hexane and n-octane can be mentioned.
• the organic solvent one kind may be used alone, or two or more kinds may be used in combination.
• the concentration of the cellulose acetate solution is not particularly limited, but is preferably 4 to 40% by mass, more preferably 8 to 16% by mass.
• the resin mixture in water in the presence of a suspension stabilizer.
• the suspension stabilizer may be added in advance to, for example, water as a dispersion medium.
• water as a dispersion medium further contains a suspension stabilizer, the suspension state tends to be stabilized, and inorganic-encapsulating cellulose particles can be more easily produced.
• the suspension stabilizer examples include cellulose-based water-soluble resins (methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, etc.), polyvinyl alcohol, polyacrylic acid salts, polyethylene glycol, polyvinylpyrrolidone, polyacrylamide, and tertiary phosphates. And so on.
• cellulose-based water-soluble resins methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, etc.
• polyvinyl alcohol polyacrylic acid salts
• polyethylene glycol polyvinylpyrrolidone
• polyacrylamide polyacrylamide
• tertiary phosphates tertiary phosphates.
• the suspension stabilizer one type may be used alone, or two or more types may be used in combination.
• the resin mixture in water in the presence of a surfactant.
• the surfactant may be added in advance to, for example, water as a dispersion medium.
• water as a dispersion medium further contains a surfactant, the suspended state tends to be stabilized, and inorganic-encapsulated cellulose particles can be more easily produced.
• the surfactant is not particularly limited, and known anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants and the like can be used.
• the surfactant one type may be used alone, or two or more types may be used in combination.
• step (b) it is preferable to prepare a dispersion medium aqueous solution in advance, suspend the resin mixed solution in the dispersion medium aqueous solution, and obtain a suspension in which cellulose acetate particles containing an inorganic substance are dispersed in water.
• a stirrer When mixing the dispersion medium aqueous solution and the resin mixture, for example, it is preferable to stir using a stirrer.
• the aqueous solution of the dispersion medium preferably contains water, the above-mentioned suspension stabilizer, and the above-mentioned surfactant.
• the content of the suspension stabilizer in the dispersion medium aqueous solution is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 8 parts by mass, and 0.3 to 7 parts by mass with respect to 100 parts by mass of water. Is more preferable, and 0.4 to 5 parts by mass is particularly preferable.
• the content of the suspension stabilizer is at least the above lower limit, the suspension state of the cellulose acetate particles and the inorganic substance in the production step is easily stabilized, and the cellulose particles encapsulating the inorganic substance can be more easily produced.
• the content of the surfactant in the dispersion medium aqueous solution is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, and 0.02 to 1.5 parts by mass with respect to 100 parts by mass of water. Parts are more preferable, and 0.03 to 0.5 parts by mass are particularly preferable.
• the content of the surfactant in the dispersion medium aqueous solution is at least the above lower limit value, the suspended state of the cellulose acetate particles in the production process is likely to be stable, and the inorganic substance-encapsulating cellulose particles can be produced more easily.
• the content of the surfactant in the aqueous solution of the dispersion medium is not more than the above upper limit value, foaming of the suspension due to stirring is less likely to occur, and the production of cellulose particles containing inorganic substances becomes easier.
• step (c) the organic solvent is removed from the suspension.
• the suspension it is considered that cellulose acetate particles containing an inorganic substance and an organic solvent are dispersed in water as oil. Therefore, by removing the organic solvent from the suspension in the step (c), an aqueous dispersion in which the cellulose acetate particles containing an inorganic substance are dispersed in water can be obtained.
• the organic solvent By heating the organic solvent to a boiling point equal to or higher than that of water in the step (c), the organic solvent can be sufficiently removed and the amount of the organic solvent remaining in the cellulose particles can be reduced to an extremely low level.
• the heating temperature is preferably 1013 hPa and 100 ° C. or lower.
• the cellulose acetate particles containing an inorganic substance are in the form of a slurry dispersed in water.
• the heating temperature of the cellulose acetate particles is higher than 100 ° C., water is volatilized and removed together with the organic solvent, so that the cellulose acetate particles may be fused to each other.
• the cellulose acetate particles containing an inorganic substance are saponified to obtain the inorganic substance-encapsulating cellulose particles in which the cellulose particles contain an inorganic substance.
• the saponification reaction can be carried out, for example, by mixing an aqueous dispersion in which cellulose acetate particles containing an inorganic substance are dispersed in water and a basic compound, and heating as necessary.
• the basic compound used for saponification is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, ammonia, and triethylamine.
• the basic compound one kind may be used alone, or two or more kinds may be used in combination.
• the reaction time of the saponification reaction is preferably 1.5 to 4 hours, more preferably 2 to 3 hours.
• the reaction time of the saponification reaction is at least the above lower limit value, deacetylation is likely to proceed sufficiently, and the acetic acid odor of the cellulose particles contained in the inorganic substance is likely to be reduced.
• the reaction time of the saponification reaction is not more than the above upper limit value, the time required for one manufacturing step can be shortened and the manufacturing efficiency can be improved.
• the reaction temperature of the saponification reaction is preferably 90 to 100 ° C, more preferably 93 to 98 ° C.
• the reaction temperature of the saponification reaction is at least the above lower limit value, deacetylation is likely to proceed sufficiently, and the acetic acid odor of the cellulose particles contained in the inorganic substance is likely to be reduced.
• the reaction temperature of the saponification reaction is not more than the above upper limit, there is a tendency that it is not necessary to heat the reaction solution (aqueous dispersion of cellulose acetate particles containing an inorganic substance) more than necessary, and the cellulose containing an inorganic substance is further inexpensive. Particles can be produced more easily.
• the amount of substance of the hydroxyl group in the basic compound is preferably 90 to 100 mol%, more preferably 95 to 100 mol%, based on 100 mol% of the number of moles of the acetyl group of cellulose acetate. It is preferable, 98 to 100 mol% is more preferable.
• the amount of substance of the hydroxyl group in the basic compound is at least the above lower limit value, deacetylation is likely to proceed sufficiently, and the acetic acid odor of the cellulose particles encapsulating the inorganic substance is likely to be reduced.
• the amount of the substance of the hydroxyl group in the basic compound is not more than the above upper limit value, it tends to be unnecessary to use more than the required amount of the basic compound, and the inorganic substance-encapsulating cellulose particles can be more easily produced at a lower cost.
• step (e) water is removed from the saponified aqueous dispersion obtained in the step (d), and the cellulose particles encapsulating the inorganic substance are dried.
• the method for removing water from the aqueous dispersion after saponification is not particularly limited, but for example, a method for removing water by solid-liquid separation is preferable.
• the time and temperature for solid-liquid separation can be appropriately set according to the use of the cellulose particles contained in the inorganic substance.
• the details and preferred embodiments of the inorganic-encapsulated cellulose particles obtained by the method for producing the inorganic-encapsulated cellulose particles of the present embodiment can be the same as those described in the above-mentioned "Inorganic-encapsulated cellulose particles" section.
• the inorganic substance-encapsulating cellulose particles of the present invention described above are excellent in low hygroscopicity because the inorganic substance is encapsulated in the cellulose particles. Further, according to the method for producing inorganic-encapsulated cellulose particles of the present invention, inorganic-encapsulated cellulose particles having excellent low hygroscopicity can be easily produced.
• the inorganic substance-encapsulating cellulose particles according to the present invention can be used as microbeads used as fillers for paints, plastics, adhesives, cosmetics, paper coating materials, fiber processing materials, writing tools, markers and the like.
• volume average particle size of the inorganic substance-encapsulated cellulose particles was measured using a laser diffraction type particle size distribution meter (“SALD2100” manufactured by Shimadzu Corporation).
• the hygroscopicity of the cellulose particles contained in the inorganic substance was determined as follows. After drying the inorganic-encapsulated cellulose particles at 110 ° C. for 15 hours in advance, the particles were left in an atmosphere of 100% humidity and 85 ° C. to absorb moisture into the inorganic-encapsulated cellulose particles. When 2 hours had passed from the start of leaving, the inorganic substance-encapsulated cellulose particles were collected, and the mass (W 11 ) of the inorganic-encapsulated cellulose particles after moisture absorption was measured. After measuring the mass, the inorganic substance-encapsulated cellulose particles were dried at 110 ° C.
• N 1 (mass%) W 12 / W 11 ⁇ 100 ⁇ ⁇ ⁇ (i)
• N 2 (mass%) W 22 / W 21 ⁇ 100 ⁇ ⁇ ⁇ (ii)
• Hygroscopicity (%) (N 1- N 2 ) / N 2 x 100 ... (iii)
• Example 1 500 g of water was placed in a separable flask equipped with a 2 L stirrer, and 12 g of hydroxypropylmethyl cellulose (corresponding to 2.4 parts by mass with respect to 100 parts by mass of water) and 0.5 g of sodium lauryl sulfate (with respect to 100 parts by mass of water) were charged therein. To prepare an aqueous dispersion medium solution by dissolving (corresponding to 0.1 part by mass). Separately from this, 600 g of ethyl acetate was placed in a separable flask equipped with a 2 L stirrer, and 90 g of cellulose acetate (glycation degree 55%) was dissolved therein to prepare a cellulose acetate solution.
• the temperature was raised to 95 ° C., 35 g of sodium hydroxide was added, and the mixture was held for 1.5 hours to desorb the acetyl group from the cellulose acetate particles to obtain inorganic-encapsulated cellulose particles in which the cellulose particles contained an inorganic substance. rice field.
• a slurry in which inorganic-encapsulated cellulose particles were dispersed in water was obtained.
• the slurry was cooled to room temperature, solid-liquid separated by filtration, and the recovered solid was sufficiently washed with water and then dried at 70 ° C. for 20 hours to obtain spherical inorganic substance-encapsulated cellulose particles.
• Table 1 shows the mass ratio (inorganic substance / cellulose) of the inorganic substance and the cellulose in the inorganic substance-encapsulating cellulose particles.
• Example 2 An aqueous dispersion medium solution was prepared in the same manner as in Example 1. Separately, 700 g of ethyl acetate was placed in a separable flask equipped with a 2 L stirrer, and 90 g of cellulose acetate (glycemicization degree 55%) was dissolved therein to prepare a cellulose acetate solution. 790 g of the obtained cellulose acetate solution and 90 g of calcium carbonate ("AFF-STF" manufactured by Fimatec Limited, refractive index: about 1.7) surface-treated with stearic acid as an inorganic substance (100 parts by mass of cellulose acetate). A resin mixture was prepared by mixing with (corresponding to 100 parts by mass).
• AFF-STF calcium carbonate
• Spherical inorganic substance-encapsulated cellulose particles were obtained in the same manner as in Example 1 except that the obtained dispersion medium aqueous solution and resin mixed solution were used. The volume average particle size and hygroscopicity of the obtained inorganic-encapsulated cellulose particles were measured. The results are shown in Table 1.
• Table 1 shows the mass ratio (inorganic substance / cellulose) of the inorganic substance and the cellulose in the inorganic substance-encapsulating cellulose particles.
• Example 3 An aqueous dispersion medium solution was prepared in the same manner as in Example 1. Separately from this, 750 g of ethyl acetate was placed in a separable flask equipped with a 2 L stirrer, and 90 g of cellulose acetate (glycemicization degree 55%) was dissolved therein to prepare a cellulose acetate solution. 840 g of the obtained cellulose acetate solution and 40 g of calcium carbonate (“AFF-STF” manufactured by Fimatec Limited, refractive index: about 1.7) surface-treated with stearic acid as an inorganic substance (100 parts by mass of cellulose acetate).
• AFF-STF calcium carbonate
• Example 1 (Corresponding to 44.4 parts by mass) was mixed to prepare a resin mixed solution.
• Spherical inorganic substance-encapsulated cellulose particles were obtained in the same manner as in Example 1 except that the obtained dispersion medium aqueous solution and resin mixed solution were used.
• the volume average particle size and hygroscopicity of the obtained inorganic-encapsulated cellulose particles were measured. The results are shown in Table 1.
• Table 1 shows the mass ratio (inorganic substance / cellulose) of the inorganic substance and the cellulose in the inorganic substance-encapsulating cellulose particles.
• Example 4 500 g of water was placed in a separable flask equipped with a 2 L stirrer, and 6 g of polyvinyl alcohol (corresponding to 1.2 parts by mass with respect to 100 parts by mass of water) and 0.5 g of sodium lauryl sulfate (with respect to 100 parts by mass of water) were charged therein.
• An aqueous solution of the dispersion medium was prepared by dissolving (corresponding to 0.1 part by mass).
• a resin mixed solution was prepared in the same manner as in Example 1.
• Spherical inorganic substance-encapsulated cellulose particles were obtained in the same manner as in Example 1 except that the obtained dispersion medium aqueous solution and resin mixed solution were used.
• Table 1 shows the mass ratio (inorganic substance / cellulose) of the inorganic substance and the cellulose in the inorganic substance-encapsulating cellulose particles.
• Example 5 500 g of water was placed in a separable flask equipped with a 2 L stirrer, and 3 g of hydroxypropylmethyl cellulose (corresponding to 0.6 parts by mass with respect to 100 parts by mass of water) and 0.2 g of sodium lauryl sulfate (with respect to 100 parts by mass of water) were charged therein. (Corresponding to 0.04 part by mass) was dissolved to prepare an aqueous dispersion medium solution. Separately from this, a resin mixed solution was prepared in the same manner as in Example 1. Spherical inorganic substance-encapsulated cellulose particles were obtained in the same manner as in Example 1 except that the obtained dispersion medium aqueous solution and resin mixed solution were used.
• Table 1 shows the mass ratio (inorganic substance / cellulose) of the inorganic substance and the cellulose in the inorganic substance-encapsulating cellulose particles.
• Example 6 An aqueous dispersion medium solution was prepared in the same manner as in Example 1. Separately from this, 750 g of ethyl acetate was placed in a separable flask equipped with a 2 L stirrer, and 90 g of cellulose acetate (glycemicization degree 55%) was dissolved therein to prepare a cellulose acetate solution. 840 g of the obtained cellulose acetate solution and 30 g of calcium stearate ("calcium stearate" manufactured by Tannan Chemical Industry Co., Ltd., refractive index: about 1.5) treated with stearic acid as an inorganic substance (100 g of cellulose acetate).
• calcium stearate manufactured by Tannan Chemical Industry Co., Ltd., refractive index: about 1.5
• a cellulose acetate solution 1000 g was placed in a separable flask equipped with a 2 L stirrer, and 250 g of cellulose acetate (glycemicization degree 55%) was dissolved therein to prepare a cellulose acetate solution.
• the obtained cellulose acetate solution is also referred to as a resin mixed solution in Comparative Example 1.
• the dispersion medium aqueous solution was added to the cellulose acetate solution to prepare a suspension. Then, the suspension was heated to 90 ° C. while stirring at a rotation speed of a stirrer at 300 rpm, and heated at 90 ° C. for 2 hours to volatilize ethyl acetate from the suspension.
• Table 1 The abbreviations in Table 1 are as follows. -HPMC: Hydroxypropylmethylcellulose. -PVA: Polyvinyl alcohol.
• the inorganic substance-encapsulating cellulose particles obtained in each example had a low hygroscopicity and were excellent in low hygroscopicity.
• the cellulose particles containing no inorganic substance had a high hygroscopicity and were inferior in low hygroscopicity to the inorganic substance-encapsulating cellulose particles obtained in each example.

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