JP2020165058A - Manufacturing method of composite - Google Patents

Abstract

To provide a technology for manufacturing a composite of an inorganic material and a fiber.SOLUTION: A composite of an inorganic material and a fiber is efficiently produced by a method involving [step 1] a step of dispersing a fiber in a solvent, [step 2] a step of adding an agent to a fiber dispersion obtained in the step 1 for production reaction of a composite of an inorganic material and the fiber, and [step 3] a step of careful selection treatment of the composite of the inorganic material and the fiber from a suspension of the composite of the inorganic material and the fiber obtained in the step 2.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a composite of an inorganic substance and a fiber whose fiber surface is coated with the inorganic substance. In particular, the present invention relates to a method for producing a composite of an inorganic substance and a fiber in which 5% or more of the fiber surface is coated with the inorganic substance.

Fibers exhibit various properties based on the functional groups on the surface, but depending on the application, it may be necessary to modify the surface, and techniques for surface modification of fibers have been developed so far. There is.

For example, regarding a technique for precipitating inorganic particles on a fiber such as a cellulose fiber, Patent Document 1 describes a composite in which crystalline calcium carbonate is mechanically bonded to the fiber. Further, Patent Document 2 describes a technique for producing a composite of pulp and calcium carbonate by precipitating calcium carbonate in a pulp suspension by a carbon dioxide gas method. Patent Document 3 describes a method of adding a large amount of filler to fibers for paper and paperboard to improve the whiteness and cleanliness of waste paper fibers, in which a slurry of waste paper pulp is sent to a gas-liquid contact device to flow. A technique for adhering the filler to the fiber surface by contacting the pulp with the alkali salt slurry in the flow direction in the hydrolyzed region and sending an appropriate reactive gas and mixing with the sedimentation filler is described.

Further, Patent Documents 4 and 5 disclose a technique for producing a fiber web in which calcium carbonate is efficiently incorporated by precipitating calcium carbonate in a step of forming a fiber web (wet paper).

Japanese Patent Application Laid-Open No. 06-158585 U.S. Pat. No. 5,679,220 U.S. Pat. No. 5,665,205 Special Table 2013-521417 U.S. Patent Publication No. 2011/0000633

However, as for the production methods of various composites including the production methods described in these, the production methods at the laboratory level are only disclosed, and in large-scale production, efficient production methods are available. The current situation is that it is not disclosed.

Therefore, an object of the present invention is to provide an efficient production method for large-scale production of a composite of an inorganic substance and a fiber whose fiber surface is coated with the inorganic substance.

The present invention is not limited to this, but includes the following inventions.
(1) A method for producing a composite of an inorganic substance and a fiber, which comprises the following steps 1 to 3.
[Step 1] Step of dispersing fibers in a solvent
[Step 2] A step of adding a chemical to the fiber dispersion obtained in step 1 to form and react an inorganic substance and a fiber complex.
[Step 3] In the step (2) [Step 3] of carefully selecting the inorganic / fiber composite from the suspension of the inorganic / fiber composite obtained in Step 2, the inorganic / fiber composite is suspended. The method for producing a composite according to (1), which comprises subjecting the liquid to a selection treatment so that the fine fibers and / or inorganic particles of 140 mesh paths measured according to the pulp sieving test method of JIS P 8207 are 50% or less. ..
(3) The method according to (1) to (2), wherein in [Step 2], an acid and / or an alkali is added to the dispersion of fibers obtained in Step 1 to adjust the pH to a desired value. Method for producing the complex.
(4) Production of the composite according to any one of (1) to (3), which comprises molding the composite of the inorganic substance and the fiber from the suspension of the composite of the inorganic substance and the fiber obtained in step 3. Method.
(5) The method for producing a composite according to any one of (1) to (4), wherein the fiber is any one or more of synthetic fiber, regenerated fiber, and natural fiber.
(6) The method for producing a complex according to any one of (1) to (5), wherein the solvent is any one or two or more of water or an organic solvent.
(7) Any of (1) to (6), wherein at least a part of the inorganic substance is a metal salt of calcium, silicic acid, magnesium, zinc, barium, aluminum, or metal particles containing titanium, copper, magnesium, and zinc. The method for producing a complex according to.
(8) As the chemical according to claim 1, sodium hydroxide, sodium carbonate, titanium oxide, sulfate, aluminum sulfate, magnesium sulfate, calcium hydroxide, barium hydroxide, aluminum hydroxide, magnesium hydroxide, magnesium chloride, silicic acid. The method for producing a complex according to any one of (1) to (7), which comprises one or more of sodium, zinc sulfate, zinc chloride, copper sulfate, copper chloride, and carbon dioxide gas.
(9) The method for producing a composite according to any one of (1) to (8), which comprises a step of beating the fibers before the step 2.
(10) The method for producing a composite according to any one of (1) to (10), wherein the fiber and the chemical are mixed using a stirrer in the step 2.
(11) The method for producing a composite according to any one of (1) to (10), wherein the fiber and the chemical are mixed by using circulation, circulation or jet flow by a pump in the step 2.
(12) The method for producing a composite according to any one of claims 1 to 11, wherein the step 2 is a batch type or a continuous type.
(13) In any of (1) to (12), in the step 3, the suspension of the composite of the inorganic substance and the fiber is concentrated by using any of filtration type separation, sedimentation concentration, evaporation concentration, and pressure dehydration. The method for producing the complex described in Crab.
(14) The method for producing a composite according to any one of (1) to (13), which is a composite in which 5% or more of the fiber surface is coated with an inorganic substance.
(15) The method for producing a composite according to any one of (1) to (14), which is a composite in which an inorganic substance is self-fixed to fibers.

According to the present invention, it is possible to provide an efficient production method for large-scale production of a composite of an inorganic substance and a fiber whose fiber surface is covered with the inorganic substance.

FIG. 1 is a schematic view of the reactor used in Example 1 of the present invention. FIG. 2 is a schematic view showing an ultrafine bubble generator used in Experiment 1. FIG. FIG. 3 is a schematic view of the reaction device used in Example 1 of the present invention (cavitation device).

The present invention relates to fibers whose surface is coated with an inorganic substance. In particular, the present invention relates to a fiber / inorganic composite in which 5% or more of the fiber surface is coated with an inorganic substance, and a method for producing the same.

Further, in the composite of the fiber and the inorganic substance obtained by the present invention, the fiber and the inorganic substance are not simply mixed, but the fiber and the inorganic substance are self-fixed to some extent by hydrogen bonding or the like, so that the inorganic substance can be obtained even by the dissociation treatment. It is unlikely to drop out. The strength of binding of fibers and inorganic substances in the composite can be evaluated by, for example, a numerical value such as ash yield (%), that is, (ash content of sheet ÷ ash content of composite before dissociation) × 100. Specifically, the complex is dispersed in water to adjust the solid content concentration to 0.2%, and the mixture is dissociated with a standard disintegrator specified in JIS P 820-1: 2012 for 5 minutes, and then according to JIS P 8222: 1998. The ash yield when sheeted using a 150 mesh wire can be used for evaluation, and the ash yield is 20% by mass or more in a preferable embodiment, and the ash yield is 50% by mass or more in a more preferable embodiment. is there.

1. 1. Overall Production Flow The present invention relates to a method for producing a composite of an inorganic substance and a fiber, which comprises a step of dispersing the fiber in a solvent, a step of adding and reacting a chemical, and a step of concentrating the fiber.

2. Fiber In the present invention, for example, not only natural cellulose fiber but also regenerated fiber (semi-synthetic fiber) such as rayon and lyocell, synthetic fiber and the like can be used without limitation. As a raw material for cellulose fiber, it is produced by microorganisms such as pulp fiber (bleached or unbleached wood pulp, refined linter, jute, herbaceous pulp such as Manila hemp and kenaf, or non-wood pulp), cellulose nanofiber, and acetic acid bacteria. Bacterial cellulose, animal-derived cellulose such as squirrel, algae, etc., and fine cellulose obtained by hydrolyzing, alkaline hydrolysis, enzymatic decomposition, blasting, mechanical treatment such as vibration ball mill, etc. Examples include cellulose. Wood pulp may be produced by pulping wood raw materials. Wood raw materials include red pine, black pine, todo pine, spruce, beni pine, larch, fir, tsuga, sugi, hinoki, larch, white pine, spruce, hiba, douglas fur, hemlock, white fur, spruce, balsam fur, cedar, pine, Conifers such as Merck pine and Radiata pine, and their mixtures, beech, hippo, hannoki, nara, tab, shii, white hippopotamus, larch, poplar, fir, doroyanagi, eucalyptus, mangrove, lauan, acacia and other broad-leaved trees and their mixture. The material is exemplified.

The method of pulping a natural material such as a wood raw material (wood raw material) is not particularly limited, and a pulping method generally used in the paper industry is exemplified. Wood pulp can be classified by the pulping method, for example, chemical pulp that has been vaporized by methods such as the craft method, sulfite method, soda method, and polysulfide method; mechanical pulp obtained by pulping by mechanical force such as a refiner and grinder; chemicals. Examples thereof include semi-chemical pulp; used paper pulp; and deinked pulp obtained by pulping by mechanical force after pretreatment with. The wood pulp may be in an unbleached (before bleaching) state or in a bleached (after bleaching) state.

Examples of non-wood-derived pulp include cotton, hemp, sisal, Manila hemp, flax, straw, bamboo, bagasse, kenaf, sugar cane, corn, rice straw, kozo, and mitsumata.

The pulp fiber may be unbeaten or beaten, and may be selected according to the physical properties of the composite sheet, but beating is preferable. This can be expected to improve the sheet strength and promote the fixation of inorganic substances.

Further, these cellulose raw materials are further treated to carry out powdered cellulose, chemically modified cellulose such as oxidized cellulose, and cellulose nanofibers: CNF (microfibrillated cellulose: MFC, TEMPO oxide CNF, phosphate esterified CNF, carboxymethylation). It can also be used as CNF, machine crushed CNF, etc.). The powdered cellulose used in the present invention has a constant particle size having a rod-like shape, which is produced by, for example, purifying and drying an undecomposed residue obtained after acid-hydrolyzing selected pulp, pulverizing and sieving. A crystalline cellulose powder having a distribution may be used, or commercially available products such as KC Flock (manufactured by Nippon Paper Co., Ltd.), Theoras (manufactured by Asahi Kasei Chemicals), and Abyssel (manufactured by FMC) may be used. The degree of polymerization of cellulose in powdered cellulose is preferably about 100 to 1500, the degree of crystallinity of powdered cellulose by X-ray diffraction is preferably 70 to 90%, and the volume average particle diameter by a laser diffraction type particle size distribution measuring device. Is preferably 1 μm or more and 100 μm or less. The cellulose oxide used in the present invention can be obtained by oxidizing in water with an oxidizing agent in the presence of, for example, an N-oxyl compound and a compound selected from the group consisting of bromide, iodide or a mixture thereof. it can.

As the cellulose nanofiber, the method of defibrating the cellulose raw material is used. As a defibration method, for example, an aqueous suspension of chemically modified cellulose such as cellulose or oxidized cellulose is mechanically ground by a refiner, a high-pressure homogenizer, an ultra-high-pressure homogenizer, a grinder, a uniaxial or multiaxial kneader, a bead mill or the like. , Or a method of defibrating by beating can be used. Cellulose nanofibers may be produced by combining one or more of the above methods. The fiber diameter of the produced cellulose nanofibers can be confirmed by observation with an electron microscope or the like, and is, for example, in the range of 5 nm to 1000 nm, preferably 5 nm to 500 nm, and more preferably 5 nm to 300 nm.

When producing the cellulose nanofibers, before and / or after the cellulose is defibrated and / or finely divided, an arbitrary compound may be further added and reacted with the cellulose nanofibers to modify the hydroxyl groups. it can. Functional groups to be modified include acetyl group, ester group, ether group, ketone group, formyl group, benzoyl group, acetal, hemiacetal, oxime, isonitrile, allene, thiol group, urea group, cyano group, nitro group and azo group. , Aryl group, aralkyl group, amino group, amide group, imide group, acryloyl group, methacryloyl group, propionyl group, propioloyl group, butyryl group, 2-butyryl group, pentanoyl group, hexanoyl group, heptanoyle group, octanoyl group, nonanoyl group. , Decanoyl group, undecanoyl group, dodecanoyl group, myritoyl group, palmitoyl group, stearoyl group, pivaloyl group, benzoyl group, naphthoyl group, nicotinoyyl group, isonicotinoyl group, floyl group, cinnamoyl group and other acyl groups, 2-methacryloyloxyethyl isothia Isocyanate group such as noyl group, methyl group, ethyl group, propyl group, 2-propyl group, butyl group, 2-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl Examples thereof include an alkyl group such as a group, an undecyl group, a dodecyl group, a myristyl group, a palmityl group and a stearyl group, an oxylan group, an oxetane group, an oxyl group, a thiirane group and a thietan group. Hydrogen in these substituents may be substituted with a functional group such as a hydroxyl group or a carboxy group. Further, a part of the alkyl group may have an unsaturated bond. The compound used for introducing these functional groups is not particularly limited, and for example, a compound having a phosphoric acid-derived group, a compound having a carboxylic acid-derived group, a compound having a sulfuric acid-derived group, and a sulfonic acid-derived compound. Examples thereof include a compound having a group of, a compound having an alkyl group, a compound having a group derived from amine, and the like.

The compound having a phosphoric acid group is not particularly limited, and examples thereof include phosphoric acid, lithium dihydrogen phosphate which is a lithium salt of phosphoric acid, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. .. Further, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium polyphosphate, which are sodium salts of phosphoric acid, can be mentioned. Further, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium polyphosphate, which are potassium salts of phosphoric acid, can be mentioned. Further, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium polyphosphate, etc., which are ammonium salts of phosphoric acid, can be mentioned. Of these, phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, and ammonium salt of phosphoric acid are preferable, and sodium dihydrogen phosphate is preferable from the viewpoint of high efficiency of introduction of phosphoric acid group and easy industrial application. , Disodium hydrogen phosphate is more preferable, but it is not particularly limited. The compound having a carboxyl group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid, and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. ..

The acid anhydride of the compound having a carboxyl group is not particularly limited, and examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. Be done. The derivative of the compound having a carboxyl group is not particularly limited, and examples thereof include an imide of an acid anhydride of a compound having a carboxyl group and a derivative of an acid anhydride of a compound having a carboxyl group. The imide of the acid anhydride of the compound having a carboxyl group is not particularly limited, and examples thereof include an imide of a dicarboxylic acid compound such as maleimide, succinateimide, and phthalateimide. The derivative of the acid anhydride of the compound having a carboxyl group is not particularly limited. For example, at least a part of hydrogen atoms of the acid anhydride of a compound having a carboxyl group, such as dimethylmaleic acid anhydride, diethylmaleic acid anhydride, diphenylmaleic acid anhydride, etc., are substituents (for example, alkyl group, phenyl group, etc.). ) Replaced by). Among the compounds having a group derived from the carboxylic acid, maleic anhydride, succinic anhydride, and phthalic anhydride are preferable, but are not particularly limited, because they are easily applied industrially and easily gasified. Further, the cellulose nanofibers may be modified in such a manner that the modifying compound physically adsorbs to the cellulose nanofibers without chemically binding.

Examples of the compound that is physically adsorbed include a surfactant and the like, and any of anionic, cationic and nonionic compounds may be used. If the above modification is performed before the cellulose is defibrated and / or pulverized, these functional groups can be eliminated after the defibration and / or pulverization to return to the original hydroxyl group. By applying the above-mentioned modifications, it is possible to promote the defibration of the cellulose nanofibers and facilitate the mixing with various substances when the cellulose nanofibers are used.

Synthetic fibers and composite fibers of synthetic fibers and cellulose fibers can also be used in the present invention, for example, polyester fibers, polyamide fibers, acrylic fibers, polyolefin fibers, polyvinyl alcohol-based fibers, polyurethane fibers, glass fibers, carbon fibers, etc. Various metal fibers and the like can be used alone or in combination of two or more, and composite fibers of one or more of one or more and cellulose fibers can also be used.

The fibers shown above may be used alone or in combination of two or more. Among them, it is preferable to contain wood pulp or a combination of wood pulp and non-wood pulp and / or synthetic fiber, and more preferably only wood pulp.

In a preferred embodiment, the fibers constituting the composite of the present invention are pulp fibers. Further, for example, the fibrous substance recovered from the wastewater of a paper mill may be supplied to the carbonation reaction of the present invention. By supplying such a substance to the reaction vessel, various composite particles can be synthesized, and fibrous particles and the like can be synthesized in terms of shape.

In the present invention, in addition to fibers, a substance that is incorporated into an inorganic substance as a product to form a complex can be used. In the present invention, fibers such as pulp fibers are used, but in addition to these, a composite in which these substances are further incorporated by synthesizing inorganic substances in a solution containing inorganic substances, organic substances, polymers and the like. It is possible to manufacture.

The fiber length of the composited fiber is not particularly limited, but for example, the average fiber length can be about 0.1 μm to 15 mm, and may be 1 μm to 12 mm, 100 μm to 10 mm, 500 μm to 8 mm, or the like.

The composite fiber is preferably used in an amount such that 5% or more of the fiber surface is covered with an inorganic substance. For example, the weight ratio of the fiber to the inorganic substance may be 5/95 to 95/5. It can be 10/90 to 90/10, 20/80 to 80/20, 30/70 to 70/30, 40/60 to 60/40.

In the composite produced by the present invention, 5% or more of the fiber surface is coated with an inorganic substance, and if the fiber surface is coated with such an area ratio, the characteristics caused by the inorganic substance become large. , Features due to fiber surface are reduced.

3. 3. Inorganic substances In the present invention, the inorganic substances to be composited with the fibers are not particularly limited, but are preferably inorganic substances that are insoluble or sparingly soluble in a solvent. Since the synthesis of the inorganic substance may be carried out in an aqueous system and the complex may be used in an aqueous system, it is preferable that the inorganic substance is insoluble or sparingly soluble in water.

The inorganic substance referred to here means a metal or a metal compound. Further, a metal compound, a metal cation (e.g. ^{Na +, Ca 2+, Mg 2+} , Al 3+, etc. ^{Ba 2+)} and anions _{^{(e.g., O 2-, OH -, CO}} 3 2-, PO 4 3 _{^{-, SO 4 2-, NO 3}} -, Si 2 O 3 2-, SiO 3 2-, Cl -, F -, S 2- , etc.) is Deki linked by ions, what is commonly referred to as an inorganic salt To tell. The method for synthesizing these inorganic substances may be either a gas-liquid method or a liquid-liquid method. As an example of the gas-liquid method, there is a carbon dioxide gas method. For example, magnesium carbonate can be synthesized by reacting magnesium hydroxide with carbon dioxide gas. Examples of the liquid-liquid method include reacting an acid (hydrochloric acid, sulfuric acid, etc.) with a base (sodium hydroxide, potassium hydroxide, etc.) by neutralization, reacting an inorganic salt with an acid or postponement, or combining inorganic salts with each other. Examples include a method of reacting. For example, barium sulfate can be obtained by reacting barium hydroxide with sulfuric acid, aluminum hydroxide can be obtained by reacting aluminum sulfate with sodium hydroxide, or calcium carbonate can be reacted with aluminum sulfate to obtain calcium and aluminum. Can be obtained as a composite inorganic substance. Further, when synthesizing an inorganic substance in this way, any metal or metal compound can coexist in the reaction solution, and in this case, those metals or metal compounds can be efficiently incorporated into the inorganic substance and compounded. .. For example, when phosphoric acid is added to calcium carbonate to synthesize calcium phosphate, by coexisting with titanium dioxide in the reaction solution, composite particles of calcium phosphate and titanium can be obtained.

The composite of the present invention can be obtained in one preferred embodiment by synthesizing an inorganic substance in the presence of cellulose fibers. This is because the surface of the cellulose fiber serves as a suitable place for the precipitation of the inorganic substance, so that a composite of the inorganic substance and the cellulose fiber can be easily synthesized.

As one preferred embodiment, the inorganic substance in the composite of the present invention can be, for example, inorganic particles having an average primary particle size of 1 μm or less, but an inorganic particle having an average primary particle size of 500 nm or less or an average primary particle size. Inorganic particles having an average primary particle diameter of 200 nm or less, inorganic particles having an average primary particle diameter of 100 nm or less, and inorganic particles having an average primary particle diameter of 50 nm or less can be used. Further, the average primary particle diameter of the inorganic particles can be 10 nm or more. The average primary particle size can be calculated from an electron micrograph.

In addition, the inorganic particles in the composite of the present invention may take the form of secondary particles in which fine primary particles are aggregated, so that secondary particles suitable for the intended use can be generated by the aging step, and by pulverization. The agglomerates can also be made finer. As a crushing method, a ball mill, a sand grinder mill, an impact mill, a high pressure homogenizer, a low pressure homogenizer, a dyno mill, an ultrasonic mill, a kanda grinder, an attritor, a stone mill, a vibration mill, a cutter mill, a jet mill, a breaker, and a beating machine. , Short-screw extruder, twin-screw extruder, ultrasonic stirrer, household juicer mixer and the like.

The average particle size, shape, etc. of the inorganic particles constituting the composite of the present invention can be confirmed by observation with an electron microscope. Further, by adjusting the conditions for synthesizing the inorganic substance, the inorganic substance having various sizes and shapes can be complexed with the fiber.

Hereinafter, preferred embodiments of each step will be described, but this is not always the case when producing the composite of the present invention. Between each process, tanks and storages equipped with agitation equipment, heating and cooling equipment, and pumps for loading and unloading may be included, as well as hoppers and nozzles for injecting chemicals, solvents and steam. Such equipment may be provided. In addition, a tank and storage attached to the liquid feeding facility for the purpose of dissolving chemicals and adjusting the concentration may be separately installed.

4. Step 1: Preparation step In the present invention, the shape of the fiber used is not particularly limited, and for example, slurry (liquid), sheet, cotton, mash, pellet, crumble, powder, flake, etc. Fiber raw materials of one or more mixtures such as granules can be used.

The solvent for dispersing the fibers is not particularly limited. For example, water, methanol, ethanol, isopropyl alcohol, 2-butanol, 1-pentanol, octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, stearyl alcohol, glycerin, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl. Alcohols such as ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, 2-methyl-1-propanol glycerin, acetic acid, propionic acid, capric acid, capric acid, lauric acid, myristic acid, palmitic acid, oleic acid, stearer , Oleic acid, linolenic acid, lactic acid, benzoic acid, succinic acid, maleic acid, fumaric acid and other carboxylic acids, hexane, heptane, octane, decane, liquid paraffin and other hydrocarbons, toluene, xylene, ethylbenzene, naphthalene and the like. Aromatic hydrocarbons, dimethylsulfoxide, dimethylformamide, dimethylacetamide, acetanilide and other amides, acetone, methylethylketone, diethylketone, methylisobutylketone, cyclohexanone, benzophenone and other ketones, methylene chloride, chloroform, carbon tetrachloride, trichloroethylene , Halogens such as tetrachloroethylene, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl butyrate, di2-ethylhexyl adipate, diisononyl adipate, adipine Diisodecyl acid, di2-ethylhexyl sebacate, di2-ethylhexyl azelaine, 4-cyclohexene-1,2-dicarboxylic acid bis (2-ethylhexyl), tricresyl phosphate, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, poly Esters such as oxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyethers such as polyethylene glycol, polytetramethylene oxide, polyoxyethylene alkyl ether, silicone oils such as polydimethylsiloxane, dimethylsulfoxide , Acetonitrile, propionitrile, ester oil, light oil, kerosene, crude oil, salad oil, soybean oil, castor oil, triglyceride, polyisoprene, Fluorine-modified oil and the like can be mentioned. These may be used alone or in combination of two or more. Further, instead of the organic solvent, an organic medium containing a reactive functional group may be used. For example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, 2-ethylhexyl acrylate, 2 methacrylic acid. -Ethylhexyl, nonanediol diacrylate, phenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, phenylglycidyl ether acrylate, hexamethylene diisocyanate urethane prepolymer, phenylglycidyl ether acrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate hexamethylene Diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, tripropylene Glycoldiglycidyl ether, neopentyl glycol diglycidyl ether, glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, chlorostyrene, methoxystyrene, butoxystyrene, vinyl benzoic acid and the like can be mentioned. Water is particularly preferable.

In the present invention, when water is used as a solvent or the like, ordinary tap water, industrial water, groundwater, well water, etc. can be used as the water, as well as ion-exchanged water, distilled water, ultrapure water, and industrial wastewater. , Water obtained when separating from the suspension of the complex in the concentration step can be preferably used.

The apparatus used for dispersing the fibers in the solvent is not particularly limited, and for example, a dissociator such as a pulper can be used. The disintegrator can also be rephrased as a stirrer. Examples of the type of pulper include low-concentration pulper, high-concentration pulper, fiber flow drum, horizontal rotation kiln, and steaming pot such as earth kiln. It is also possible to use a disperser such as a kneader, a disperser, a top finer, and a hydrorough breaker together.

The slurry concentration when the fibers are dispersed in the solvent can be 0.01% by mass to 20% by mass, preferably 0.1% by mass to 15% by mass, and more preferably 0.5 to 10% by mass. More preferably, it can be 1 to 6% by mass.

The slurry temperature at which the fibers are dispersed in the solvent can be 0 to 100 ° C, preferably 5 to 90 ° C, more preferably 10 to 80 ° C, and even more preferably 15 to 70 ° C.

The time for dispersing the fibers in the solvent can be 1 minute to 24 hours, preferably 5 minutes to 12 hours, more preferably 10 minutes to 6 hours, still more preferably 20 minutes to 3 hours. Can be done.

In this step, a dissociation accelerator, a pH adjuster such as an alkaline chemical, a defoaming agent, a pitch control agent, a slime control agent, a preservative, a fungicide, an antiscale agent, a sizing agent, a fixing agent, a yield agent, and a cation. Various additives such as a cationizing agent such as a sex resin and a polyvalent cation salt and a paper strength agent may be used as needed.

It is also possible to beat the fibers in this step. The method of beating is not particularly limited, and for example, a beating machine such as a beater, a drum type refiner, Jordan, a conical refiner, a single disc refiner, or a double disc refiner can be used.

In addition, dust can be removed in order to remove foreign matter and undissociated debris in this step. This dust removal may be performed at any timing after the pulp is dispersed (dissociated). The method of removing dust is not particularly limited, and for example, a screen or a cleaner can be used. As the screen, either an open type or a closed type can be preferably used. Further, either a round hole or a slit can be used for the plate, and the size of the eye hole can be appropriately adjusted according to the purpose. As the cleaner, either a heavyweight cleaner or a lightweight cleaner can be used.

5. Step 2: Reaction step The method for producing a composite according to the present invention is essential to synthesize an inorganic substance in a solution containing fibers. For example, a solution containing a fiber and an inorganic precursor may be stirred and mixed in an open reaction vessel to synthesize a composite, or an aqueous suspension containing a fiber and an inorganic precursor may be placed in a reaction vessel. It may be synthesized by injecting into. As will be described later, when the aqueous suspension of the precursor of the inorganic substance is injected into the reaction vessel, cavitation bubbles may be generated and the inorganic substance may be synthesized in the presence thereof.

When one of the precursors of the inorganic substance is alkaline, the fibers can be swelled by dispersing the fibers in a solution of the alkaline precursor in advance, so that a composite of the inorganic substance and the fibers can be efficiently obtained. The reaction can be started after promoting the swelling of the fibers by stirring for 15 minutes or more after mixing, but the reaction may be started immediately after mixing. When using a substance that easily interacts with cellulose, such as aluminum sulfate (aluminum sulfate band, polyaluminum chloride, etc.) as a part of the precursor of the inorganic substance, the aluminum sulfate side should be mixed with the fiber in advance. In some cases, the rate at which the inorganic particles are fixed to the fiber can be improved.

In the present invention, the liquid may be sprayed under conditions that generate cavitation bubbles in the reaction vessel, or may be sprayed under conditions that do not generate cavitation bubbles. Further, the reaction vessel is preferably a pressure vessel in any case. The pressure vessel in the present invention is a vessel capable of applying a pressure of 0.005 MPa or more. Under conditions that do not generate cavitation bubbles, the pressure in the pressure vessel is preferably 0.005 MPa or more and 0.9 MPa or less in static pressure.

(Cavitation bubbles)
When synthesizing the composite according to the present invention, inorganic particles can be precipitated in the presence of cavitation bubbles. In the present invention, cavitation is a physical phenomenon in which bubbles are generated and disappear in a short time due to a pressure difference in a fluid flow, and is also called a cavity phenomenon. Bubbles generated by cavitation (cavitation bubbles) are generated as nuclei of very small "bubble nuclei" of 100 microns or less existing in a liquid when the pressure in the fluid becomes lower than the saturated vapor pressure for a very short time.

In the present invention, cavitation bubbles can be generated in the reaction vessel by a known method. For example, cavitation bubbles are generated by injecting a fluid at high pressure, cavitation is generated by stirring at high speed in the fluid, cavitation is generated by causing an explosion in the fluid, and ultrasonic vibration. It is conceivable that cavitation is generated by the child (vibration fluid cavitation).

In particular, in the present invention, since it is easy to generate and control cavitation bubbles, it is preferable to generate cavitation bubbles by injecting a fluid at a high pressure. In this aspect, by compressing the injected liquid using a pump or the like and injecting it through a nozzle or the like at high speed, cavitation bubbles are generated at the same time as the liquid itself expands due to an extremely high shearing force in the vicinity of the nozzle and a rapid depressurization. .. The method using a fluid jet has a high efficiency of generating cavitation bubbles and can generate cavitation bubbles having a stronger decay impact force. In the present invention, controlled cavitation bubbles are present when synthesizing an inorganic substance, which is clearly different from cavitation bubbles that cause uncontrollable harm spontaneously occurring in a fluid machine.

In the present invention, a reaction solution such as a raw material can be used as it is as an injection liquid to generate cavitation, or some fluid can be injected into the reaction vessel to generate cavitation bubbles. The fluid formed by the liquid jet may be a liquid, a gas, a solid such as powder or pulp, or a mixture thereof, as long as it is in a fluid state. Further, if necessary, another fluid such as carbon dioxide gas can be added to the above fluid as a new fluid. The above fluid and the new fluid may be uniformly mixed and injected, or may be injected separately.

A liquid jet is a jet of a liquid or a fluid in which solid particles or gas are dispersed or mixed in the liquid, and refers to a liquid jet containing a raw material slurry or bubbles of pulp or inorganic particles. The gas referred to here may contain bubbles due to cavitation.

Flow velocity and pressure are of particular importance because cavitation occurs when the liquid is accelerated and the local pressure drops below the vapor pressure of the liquid. From this, the basic dimensionless number representing the cavitation state, the cavitation number σ, is defined as the following formula 1 (edited by Yoji Kato, "New Edition Cavitation / Basics and Recent Advances", Maki Shoten. , 1999).

Here, a large number of cavitations indicates that the flow field is in a state in which cavitation is unlikely to occur. In particular, when cavitation is generated through a nozzle or orifice pipe such as a cavitation jet, the cavitation number σ is as shown in the following equation (2) from the nozzle upstream pressure p1, the nozzle downstream pressure p2, and the saturated vapor pressure pv of the sample water. In the cavitation jet, the pressure difference between p1, p2, and pv is large, and p1 >> p2 >> pv. Therefore, the cavitation number σ can be further approximated by the following equation 2. (H. Soyama, J. Soc. Mat. Sci. Japan, 47 (4), 381, 1998).

As for the cavitation conditions in the present invention, the above-mentioned cavitation number σ is preferably 0.001 or more and 0.5 or less, preferably 0.003 or more and 0.2 or less, and 0.01 or more and 0.1 or less. Is particularly preferable. When the cavitation number σ is less than 0.001, the effect is small because the pressure difference with the surroundings when the cavitation bubble collapses is small, and when it is larger than 0.5, the pressure difference of the flow is low and the cavitation is It becomes difficult to occur.

Further, when injecting the injection liquid through a nozzle or an orifice pipe to generate cavitation, the pressure of the injection liquid (upstream pressure) is preferably 0.01 MPa or more and 30 MPa or less, and 0.7 MPa or more and 20 MPa or less. It is preferably 2 MPa or more and 15 MPa or less more preferably. If the upstream pressure is less than 0.01 MPa, it is difficult to generate a pressure difference with the downstream pressure, and the effect is small. Further, if it is higher than 30 MPa, a special pump and a pressure vessel are required, and energy consumption becomes large, which is disadvantageous in terms of cost. On the other hand, the pressure inside the container (downstream pressure) is preferably 0.005 MPa or more and 0.9 MPa or less in static pressure. The ratio of the pressure in the container to the pressure of the injection liquid is preferably in the range of 0.001 to 0.5.

In the present invention, it is also possible to synthesize inorganic particles by injecting a jet solution under conditions such that cavitation bubbles are not generated. Specifically, it is more preferable that the pressure of the injection liquid (upstream side pressure) is 2 MPa or less, preferably 1 MPa or less, and the pressure of the injection liquid (downstream side pressure) is released to 0.05 MPa or less.

The jet velocity of the jet liquid is preferably in the range of 1 m / sec or more and 200 m / sec or less, and preferably in the range of 20 m / sec or more and 100 m / sec or less. When the jet velocity is less than 1 m / sec, the pressure drop is low and cavitation is unlikely to occur, so the effect is weak. On the other hand, if it is larger than 200 m / sec, high pressure is required and a special device is required, which is disadvantageous in terms of cost.

The place where cavitation is generated in the present invention may be generated in a reaction vessel for synthesizing inorganic particles. It is also possible to process with one pass, but it is also possible to circulate as many times as necessary. Furthermore, it can be processed in parallel or in a permutation using a plurality of generating means.

The injection of the liquid to generate cavitation may be done in an air-open container, but is preferably done in a pressure vessel to control cavitation.

When cavitation is generated by liquid injection, the solid content concentration of the reaction solution is preferably 30% by weight or less, more preferably 20% by weight or less. This is because such a concentration makes it easy for the cavitation bubbles to act uniformly on the reaction system. Further, the aqueous suspension of slaked lime, which is a reaction solution, preferably has a solid content concentration of 0.1% by weight or more from the viewpoint of reaction efficiency.

In the present invention, for example, when synthesizing a complex of calcium carbonate and cellulose fibers, the pH of the reaction solution is on the basic side at the start of the reaction, but changes to neutral as the carbonation reaction proceeds. Therefore, the reaction can be controlled by monitoring the pH of the reaction solution.

In the present invention, by increasing the injection pressure of the liquid, the flow velocity of the injection liquid increases, and the pressure decreases accordingly, so that stronger cavitation can be generated. Further, by pressurizing the pressure in the reaction vessel, the pressure in the region where the cavitation bubbles collapse increases, and the pressure difference between the bubbles and the surroundings increases, so that the bubbles collapse violently and the impact force can be increased. Furthermore, it is possible to promote the dissolution and dispersion of the carbon dioxide gas to be introduced. Reaction temperature is 0 ° C or higher 90
The temperature is preferably 10 ° C or lower, and particularly preferably 10 ° C or higher and 60 ° C or lower. Generally, it is considered that the impact force is maximized at the midpoint between the melting point and the boiling point. Therefore, in the case of an aqueous solution, about 50 ° C. is preferable, but even if the temperature is lower than that, it is affected by the vapor pressure. Therefore, a high effect can be obtained within the above range.

In the present invention, the energy required to generate cavitation can be reduced by adding a surfactant. The surfactants used include known or novel surfactants, such as nonionic surfactants such as fatty acid salts, higher alkyl sulphates, alkylbenzene sulfonates, higher alcohols, alkylphenols, alkylene oxide adducts such as fatty acids. , Anionic surfactants, cationic surfactants, amphoteric surfactants and the like. It may consist of these single components or a mixture of two or more components. The amount added may be any amount necessary to reduce the surface tension of the injection liquid and / or the injection liquid.

In one embodiment of the present invention, the complex can be synthesized by synthesizing an inorganic substance in a solution containing cellulose fibers, and the method for synthesizing the inorganic substance can be a known method. In the case of synthesizing calcium carbonate, for example, calcium carbonate can be synthesized by a carbon dioxide gas method, a soluble salt reaction method, a lime / soda method, a soda method, or the like, and in a preferred embodiment, calcium carbonate is produced by the carbon dioxide gas method. Synthesize.

Generally, when calcium carbonate is produced by the carbon dioxide gas method, lime (lime) is used as a calcium source, and a slaked step of adding water to slaked lime CaO to obtain slaked lime Ca (OH) 2 and carbon dioxide CO2 are added to the slaked lime. Calcium carbonate is synthesized by a carbonization step of blowing in to obtain calcium carbonate CaCO3. At this time, a suspension of slaked lime prepared by adding water to quicklime may be passed through a screen to remove low-solubility lime grains contained in the suspension. Further, slaked lime may be directly used as a calcium source. In the present invention, when calcium carbonate is synthesized by the carbon dioxide gas method, the carbonation reaction may be carried out in the presence of cavitation bubbles.

Generally, as a reaction vessel (carbonation reactor: carbonator) for producing calcium carbonate by the carbon dioxide gas method, a gas blowing type carbonator and a mechanical stirring type carbonator are known. In the gas blowing type carbonator, carbon dioxide gas is blown into a carbonation reaction tank containing slaked lime suspension (lime milk) to react slaked lime and carbon dioxide gas, but simply blowing carbon dioxide gas is the size of bubbles. It is difficult to control the amount uniformly and finely, and there is a limit in terms of reaction efficiency. On the other hand, in the mechanical stirring type carbonator, a stirrer is provided inside the carbonator, and carbon dioxide gas is introduced near the stirrer to make carbon dioxide gas into fine bubbles and improve the reaction efficiency between slaked lime and carbon dioxide gas. ("Cement, Carbon Dioxide, Lime Handbook", Gihodo Publishing Co., Ltd., 1995, p. 495).

When calcium carbonate is synthesized by the carbon dioxide method, the solid content concentration of the aqueous suspension of slaked lime is preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight, still more preferably 1 to 20%. It is about% by weight. If the solid content concentration is low, the reaction efficiency is low and the production cost is high, and if the solid content concentration is too high, the fluidity is poor and the reaction efficiency is low. In the present invention, since calcium carbonate is synthesized in the presence of cavitation bubbles, the reaction solution and carbon dioxide gas can be suitably mixed even if a suspension (slurry) having a high solid content concentration is used.

As the aqueous suspension containing slaked lime, those generally used for calcium carbonate synthesis can be used. For example, slaked lime is prepared by mixing with water, or quicklime (calcium oxide) is dissolved (digested) with water. Can be prepared. The conditions for reconciliation are not particularly limited, but for example, the concentration of CaO can be 0.1% by weight or more, preferably 1% by weight or more, and the temperature can be 20 to 100 ° C., preferably 30 to 100 ° C. .. The average residence time in the scavenging reaction tank (slaker) is also not particularly limited, but can be, for example, 5 minutes to 5 hours, preferably 2 hours or less. As a matter of course, the slaker may be a batch type or a continuous type. In the present invention, the carbonation reaction tank (carbonator) and the scavenging reaction tank (slaker) may be separated, or one reaction tank may be used as the carbonation reaction tank and the scavenging reaction tank. Good.

Further, in the present invention, the reaction solution in the reaction vessel can be circulated and used. By circulating the reaction solution in this way and increasing the contact between the reaction solution and carbon dioxide gas, the reaction efficiency is increased and it becomes easy to obtain a desired inorganic substance.

In the present invention, a gas such as carbon dioxide (carbon dioxide) can be blown into the reaction vessel and mixed with the reaction solution. According to the present invention, carbon dioxide gas can be supplied to the reaction solution without a gas supply device such as a fan or a blower, and the reaction can be efficiently performed because the carbon dioxide gas is refined by cavitation bubbles. ..

In the present invention, the carbon dioxide concentration of the gas containing carbon dioxide is not particularly limited, but a higher carbon dioxide concentration is preferable. The amount of carbon dioxide gas introduced into the injector is not limited and can be appropriately selected. For example, it is preferable to use carbon dioxide gas having a flow rate of 100 to 10,000 L / hour per 1 kg of slaked lime.

The carbon dioxide-containing gas of the present invention may be a substantially pure carbon dioxide gas or a mixture with other gases. For example, in addition to carbon dioxide gas, a gas containing an inert gas such as air or nitrogen can be used as the gas containing carbon dioxide. Further, as the gas containing carbon dioxide, in addition to carbon dioxide gas (carbon dioxide gas), exhaust gas discharged from an incinerator of a papermaking factory, a coal boiler, a heavy oil boiler and the like can be suitably used as the carbon dioxide-containing gas. In addition, a carbonation reaction can be carried out using carbon dioxide generated from the lime firing step.

When producing the composite of the present invention, various known auxiliaries can be further added. For example, a chelating agent can be added, specifically, polyhydroxycarboxylic acids such as citric acid, malic acid and tartaric acid, dicarboxylic acids such as oxalic acid, sugar acids such as gluconic acid, iminodiacetic acid and ethylenediamine tetra. Amino polycarboxylic acids such as acetic acid and alkali metal salts thereof, alkali metal salts of polyphosphates such as hexametaphosphate and tripolyphosphate, amino acids such as glutamic acid and aspartic acid and alkali metal salts thereof, acetylacetone, methyl acetate acetate, acetacetic acid. Examples thereof include ketones such as allyl, sugars such as sucrose, and polyols such as sorbitol. In addition, as a surface treatment agent, saturated amino acids such as palmitic acid and stearic acid, unsaturated amino acids such as oleic acid and linoleic acid, resin acids such as alicyclic carboxylic acid and avietic acid, their salts, esters and ethers, and alcohols. Activators, sorbitan fatty acid esters, amide and amine surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonylphenyl ethers, sodium alphaolefin sulfonate, long chain alkyl amino acids, amine oxides, alkylamines, fourth Secondary ammonium salts, aminocarboxylic acids, phosphonic acids, polyvalent carboxylic acids, condensed phosphoric acids and the like can be added. Further, a dispersant can also be used if necessary. Examples of the dispersant include sodium polyacrylate, sucrose fatty acid ester, glycerin fatty acid ester, acrylic acid-maleic acid copolymer ammonium salt, methacrylic acid-naphthoxypolyethylene glycol acrylate copolymer, and methacrylic acid-polyethylene glycol. There are monomethacrylate copolymer ammonium salt, polyethylene glycol monoacrylate and the like. These can be used alone or in combination of two or more. Further, the timing of addition may be before or after the synthetic reaction. Such additives can be added in an amount of preferably 0.001 to 20%, more preferably 0.1 to 10%, based on the inorganic particles.

When synthesizing the complex in the present invention, the reaction conditions are not particularly limited and can be appropriately set according to the intended use. For example, the temperature of the synthesis reaction can be 0 to 90 ° C, preferably 10 to 70 ° C. The reaction temperature can be controlled by a temperature control device, and when the temperature is low, the reaction efficiency is lowered and the cost is high, while when the temperature exceeds 90 ° C., coarse inorganic substances tend to increase.

Further, in the present invention, the reaction can be a batch reaction or a continuous reaction. In general, it is preferable to carry out the batch reaction step because of the convenience of discharging the residue after the reaction. The scale of the reaction is not particularly limited, but the reaction may be carried out on a scale of 100 L or less, or may be reacted on a scale of more than 100 L. The size of the reaction vessel may be, for example, about 10 L to 100 L, or about 100 L to 1000 L.

Further, the reaction can be controlled, for example, by monitoring the pH of the reaction solution, and depending on the pH profile of the reaction solution, if it is a calcium carbonate carbonation reaction, for example, pH less than 9, preferably less than pH 8. More preferably, the reaction can be carried out until around pH 7.

On the other hand, the reaction can also be controlled by monitoring the conductivity of the reaction solution. In the case of the carbonation reaction of calcium carbonate, for example, it is preferable to carry out the carbonation reaction until the electric conductivity drops to 1 mS / cm or less.

Further, the reaction can be controlled simply by the reaction time, and specifically, the time during which the reaction product stays in the reaction vessel can be adjusted and controlled. In addition, in the present invention, the reaction can be controlled by stirring the reaction solution in the reaction vessel or by making the reaction a multi-step reaction.

The device used in the reaction step in the present invention is not limited to the following, but for example, a machine chest (mixing chest), a carbonator, a pressurized floatator, a tank with a stirrer, and a cavitation generator (Patent No. 4291819). ) Etc. can be used. It is also possible to produce a composite by installing a stirrer or various pumps in a tank or bucket that does not have a stirrer or the like to stir and circulate the reaction solution. As the stirrer, for example, a full zone (Kobelco Eco-Solutions Co., Ltd.) or a super mix (Satake Chemical Machinery Co., Ltd.) can be used. As the pump, a submersible pump, a swirl pump, a turbine pump, a cascade pump, a piston pump, a plunger pump, a diaphragm pump, a wing pump, an injection pump and the like can be used. Furthermore, not only a batch type agitator but also a continuous type mixer can be used. These reactors can be equipped with temperature control equipment such as a jacket if necessary. Further, these devices can be suitably used in any material such as metal, resin, ceramic, concrete, and tiled.

The slurry concentration during the reaction can be appropriately determined, and can be, for example, 0.1 to 30%, 0.3 to 20%, 0.5 to 10%, 1 to 6%, or the like.

(Inorganic matter)
In the present invention, the inorganic substance to be composited with the fiber is not particularly limited, but it is preferably an inorganic substance that is insoluble in water or sparingly soluble in water. Since the synthesis of the inorganic substance may be carried out in an aqueous system and the fiber composite may be used in an aqueous system, it is preferable that the inorganic substance is insoluble or sparingly soluble in water.

The inorganic substance referred to here refers to a compound of a metallic element or a non-metallic element. The compound of a metal element, a metal cation ^{(e.g., Na +, Ca 2+, Mg} 2+, Al 3+, Ba 2+ , etc.) and anions _{^{(e.g., O 2-, OH -, CO}} 3 2-, PO 4 _{^{3-, SO 4 2-, NO 3}} -, Si 2 O 3 2-, SiO 3 2-, Cl -, F -, S 2- , etc.) is Deki linked by ionic bonds, generally referred to as inorganic salts Say something. The compound of the non-metal element is silicic acid (SiO ₂ ) or the like. In the present invention, at least a part of the inorganic material is a metal salt of calcium, magnesium or barium, or at least a part of the inorganic material is a metal salt of silicic acid or aluminum, or titanium, copper, silver, iron, manganese, cerium. Alternatively, it is preferably metal particles containing zinc.

The method for synthesizing these inorganic substances can be a known method, and either a gas-liquid method or a liquid-liquid method may be used. As an example of the gas-liquid method, there is a carbon dioxide gas method. For example, magnesium carbonate can be synthesized by reacting magnesium hydroxide with carbon dioxide gas. Examples of the liquid-liquid method include reacting an acid (hydrochloric acid, sulfuric acid, etc.) with a base (sodium hydroxide, potassium hydroxide, etc.) by neutralization, reacting an inorganic salt with an acid or base, or combining inorganic salts with each other. Examples include a method of reacting. For example, barium sulfate is obtained by reacting barium hydroxide with sulfuric acid, aluminum hydroxide is obtained by reacting aluminum sulfate with sodium hydroxide, and calcium and aluminum are obtained by reacting calcium carbonate with aluminum sulfate. A composite inorganic substance can be obtained. Further, when synthesizing an inorganic substance in this way, any metal or non-metal compound can coexist in the reaction solution. In this case, the metal or non-metal compound is efficiently incorporated into the inorganic substance, and the composite is formed. Can be converted. For example, when phosphoric acid is added to calcium carbonate to synthesize calcium phosphate, titanium dioxide is allowed to coexist in the reaction solution to obtain composite particles of calcium phosphate and titanium.

As one preferred embodiment, the average primary particle size of the inorganic substance in the composite of the present invention can be, for example, 1.5 μm or less, but the average primary particle size can also be 1200 nm or less, 900 nm or less, and further. Can also have an average primary particle size of 200 nm or less or 150 nm or less. Further, the average primary particle size of the inorganic substance can be 10 nm or more. The average primary particle size can be measured by electron micrograph.

(Calcium carbonate)
In the case of synthesizing calcium carbonate, for example, calcium carbonate can be synthesized by a carbon dioxide gas method, a soluble salt reaction method, a lime / soda method, a soda method, or the like, and in a preferred embodiment, calcium carbonate is produced by the carbon dioxide gas method. Synthesize.

Generally, when calcium carbonate is produced by the carbon dioxide method, lime (lime) is used as a calcium source, and a slaked step of adding water to slaked lime CaO to obtain slaked lime Ca (OH) ₂ and carbon dioxide CO _{2 in} slaked lime. Calcium carbonate is synthesized by a carbon dioxide step of injecting calcium carbonate to obtain CaCO ₃ . At this time, a suspension of slaked lime prepared by adding water to quicklime may be passed through a screen to remove low-solubility lime grains contained in the suspension. Further, slaked lime may be directly used as a calcium source. When calcium carbonate is synthesized by the carbon dioxide gas method in the present invention, the carbonation reaction can also be carried out in the presence of cavitation bubbles.

In the synthesis of calcium carbonate, as the raw material in the reaction mixture (Ca ion, CO ₃ ion) is at a high concentration, and if more is at low temperature conditions, but easily proceeds nucleation reactions, to produce a composite fiber, the Under such conditions, nuclei are not easily fixed to the cellulose fibers, and inorganic particles released in the suspension are easily synthesized. Therefore, it is important to appropriately control the nucleation reaction in order to produce a composite fiber in which calcium carbonate is firmly bound. Specifically, this can be achieved by optimizing the Ca ion and pulp concentrations and by slackening the amount of CO ₂ supplied per hour. For example, the Ca ion concentration in the reaction vessel is preferably 0.01 mol / L or more and less than 0.40 mol / L. If it is less than 0.01 mol / L, the reaction is difficult to proceed, and if it is 0.40 mol / L or more, inorganic particles liberated in the suspension are likely to be synthesized. The pulp concentration is preferably 0.5% or more and less than 4.0%. If it is less than 0.5%, the frequency of collision of the raw materials with the fibers decreases, so that the reaction does not proceed easily, and if it is 4.0% or more, a uniform composite cannot be obtained due to poor stirring. The amount of CO ₂ supplied per hour is determined by the balance with the concentration of Ca ions in the reaction solution, and the concentration of Ca ions (M; mol / L) in the reaction solution and the supply of carbonate ions per minute with respect to 1 L of the reaction solution. It is desirable that the ratio of amounts (mol / min · L) is 5: 1 or more. This is because when the amount of carbonate ion supplied is higher than 5: 1, nucleation is likely to proceed and inorganic particles liberated in the suspension are easily synthesized.

(Magnesium carbonate)
When synthesizing magnesium carbonate, the method for synthesizing magnesium carbonate can be a known method. For example, magnesium hydroxide can be synthesized from magnesium hydroxide and carbon dioxide gas, and basic magnesium carbonate can be synthesized from magnesium hydroxide via normal magnesium carbonate. Magnesium carbonate can be obtained from magnesium bicarbonate, normal magnesium carbonate, basic magnesium carbonate, etc. by a synthetic method, but it is particularly preferable that the magnesium carbonate according to the fiber composite of the present invention is a basic magnesium carbonate. This is because magnesium carbonate has relatively low stability, and normal magnesium carbonate, which is a columnar (needle-shaped) crystal, may be difficult to fix to the fiber. On the other hand, by chemically reacting with basic magnesium carbonate in the presence of fibers, it is possible to obtain a fiber composite of magnesium carbonate and fibers whose surface is coated in a scaly shape or the like.

Further, in the present invention, the reaction solution in the reaction vessel can be circulated and used. By circulating the reaction solution in this way and increasing the contact between the reaction solution and carbon dioxide gas, the reaction efficiency is increased and it becomes easy to obtain desired inorganic particles.

In the present invention, a gas such as carbon dioxide (carbon dioxide) can be blown into the reaction vessel and mixed with the reaction solution. According to the present invention, carbon dioxide gas can be supplied to the reaction solution without a gas supply device such as a fan or a blower, and the reaction can be efficiently performed because the carbon dioxide gas is refined by cavitation bubbles. ..

In the present invention, the carbon dioxide concentration of the gas containing carbon dioxide is not particularly limited, but a higher carbon dioxide concentration is preferable. Further, the amount of carbon dioxide gas introduced into the injector is not limited and can be appropriately selected.

The carbon dioxide-containing gas of the present invention may be a substantially pure carbon dioxide gas or a mixture with other gases. For example, in addition to carbon dioxide gas, a gas containing an inert gas such as air or nitrogen can be used as the gas containing carbon dioxide. Further, as the gas containing carbon dioxide, in addition to carbon dioxide gas (carbon dioxide gas), exhaust gas discharged from an incinerator of a papermaking factory, a coal boiler, a heavy oil boiler and the like can be suitably used as the carbon dioxide-containing gas. In addition, a carbonation reaction can be carried out using carbon dioxide generated from the lime firing step.

In the synthesis of magnesium carbonate, as a raw material in the reaction solution (Mg ion, CO ₃ ion) is at a high concentration, and if more is high temperature, but easily proceeds nucleation reactions, to produce a composite fiber, the Under such conditions, the nuclei are not easily fixed to the cellulose fibers, and the inorganic particles liberated in the suspension are easily synthesized. Therefore, in order to produce a composite fiber in which magnesium carbonate is tightly bound, it is necessary to appropriately control the nucleation reaction. Specifically, this can be achieved by optimizing the concentrations of Mg ions and pulp and gradual supply of CO ₂ per hour. For example, the Mg ion concentration in the reaction vessel is preferably 0.0001 mol / L or more and less than 0.50 mol / L. If it is less than 0.0001 mol / L, the reaction is difficult to proceed, and if it is 0.50 mol / L or more, the inorganic particles liberated in the suspension are easily synthesized. The pulp concentration is preferably 0.5% or more and less than 4.0%. If it is less than 0.5%, the frequency of collision of the raw materials with the fibers decreases, so that the reaction does not proceed easily, and if it is 4.0% or more, a uniform composite cannot be obtained due to poor stirring. The amount of CO ₂ supplied per hour is determined by the balance with the concentration of Mg ions in the reaction solution, and the concentration of Mg ions (M; mol / L) in the reaction solution and the supply of carbonate ions per minute with respect to 1 L of the reaction solution. It is desirable that the ratio of amounts (mol / min · L) is 20: 1 or more. This is because when the amount of carbonate ion supplied is higher than 20: 1, nucleation is likely to proceed and inorganic particles liberated in the suspension are easily synthesized.

(Barium sulfate)
When synthesizing barium sulfate, it is an ionic crystalline compound consisting of barium ions represented by barium sulfate (BaSO ₄ ) and sulfate ions, often in the form of plates or columns, and is sparingly soluble in water. is there. Pure barium sulfate is a colorless crystal, but when it contains impurities such as iron, manganese, strontium, and calcium, it becomes yellowish brown or blackish gray and becomes translucent. It can be obtained as a natural mineral, but it can also be synthesized by a chemical reaction. In particular, synthetic products produced by chemical reactions are used for pharmaceutical purposes (X-ray contrast agents), and are also widely used in paints, plastics, storage batteries, etc. by applying their chemically stable properties.

In the present invention, a complex of barium sulfate and fiber can be produced by synthesizing barium sulfate in a solution in the presence of fiber. For example, a method of reacting an acid (sulfuric acid or the like) with a base by neutralization, a method of reacting an inorganic salt with an acid or a base, or a method of reacting inorganic salts with each other can be mentioned. For example, barium sulfate can be obtained by reacting barium hydroxide with sulfuric acid or aluminum sulfate, or barium chloride can be added to an aqueous solution containing a sulfate to precipitate barium sulfate.

In the synthesis of barium sulfate, as a raw material in the solution (Ba ions, SO ₄ ions) is in a high concentration and the higher is the high temperature, but easily proceeds nucleation reaction, when manufacturing composite fibers, such Under such conditions, the nuclei are not easily fixed to the cellulose fibers, and the inorganic particles released in the suspension are easily synthesized. Therefore, in order to produce a composite fiber in which barium sulfate is tightly bound, it is necessary to appropriately control the nucleation reaction. Specifically, this can be achieved by optimizing the concentration of Ba ions and pulp and by gradual supply of SO ₄ ions per hour. For example, the Ba ion concentration in the reaction vessel is preferably 0.01 mol / L or more and less than 0.20 mol / L. If it is less than 0.01 mol / L, the reaction is difficult to proceed, and if it is 0.20 mol / L or more, inorganic particles liberated in the suspension are easily synthesized. The pulp concentration is preferably 0.5% or more and less than 4.0%. If it is less than 0.5%, the frequency of collision of the raw materials with the fibers decreases, so that the reaction does not proceed easily, and if it is 4.0% or more, a uniform composite cannot be obtained due to poor stirring. The amount of SO ₄ ions supplied per hour is determined by the balance with the concentration of Ba ions in the reaction solution, and the concentration of Ba ions (M; mol / L) in the reaction solution and SO ₄ per minute with respect to 1 L of the reaction solution. It is desirable that the ratio of ion supply amount (mol / min · L) is 25: 1 or more. This is because when the amount of carbonate ion supplied is higher than 25: 1, nucleation is likely to proceed and inorganic particles liberated in the suspension are easily synthesized.

(Hydrotalcite)
When synthesizing hydrotalcite, a known method can be used for synthesizing hydrotalcite. For example, the fibers are immersed in a carbonate aqueous solution containing carbonate ions constituting an intermediate layer and an alkaline solution (sodium hydroxide, etc.) in a reaction vessel, and then an acid solution (divalent metal ions and trivalent metal ions constituting the basic layer). Hydrotalcite is synthesized by a co-precipitation reaction by adding a metal salt aqueous solution containing metal ions) and controlling the temperature, pH, etc. Further, in the reaction vessel, the fibers are immersed in an acid solution (a metal salt aqueous solution containing divalent metal ions and trivalent metal ions constituting the basic layer), and then a carbonate aqueous solution containing carbonate ions constituting the intermediate layer. Hydrotalcite can also be synthesized by dropping an alkaline solution (sodium hydroxide or the like) and controlling the temperature, pH, etc. by a co-precipitation reaction. Although the reaction at normal pressure is common, there is also a method of obtaining the reaction by a hydrothermal reaction using an autoclave or the like (Japanese Patent Laid-Open No. 60-6619).

In the present invention, various chlorides, sulfides, glass oxides, and sulfates of magnesium, zinc, barium, calcium, iron, copper, cobalt, nickel, and manganese are used as sources of divalent metal ions constituting the basic layer. Can be used. Further, as a source of trivalent metal ions constituting the basic layer, various chlorides, sulfides, glass oxides and sulfates of aluminum, iron, chromium and gallium can be used.

In the present invention, carbonate ion, nitrate ion, chloride ion, sulfate ion, phosphate ion and the like can be used as the interlayer anion. When the carbonate ion is an interlayer anion, sodium carbonate is used as a source. However, sodium carbonate can be replaced with a gas containing carbon dioxide (carbon dioxide gas), and may be substantially pure carbon dioxide gas or a mixture with other gases. For example, exhaust gas emitted from an incinerator, a coal boiler, a heavy oil boiler, or the like in a paper mill can be suitably used as a carbon dioxide-containing gas. In addition, a carbonation reaction can be carried out using carbon dioxide generated from the lime firing step.

In the synthesis of hydrotalcite, as (metal ions constituting the base layer, CO ₃ ion) material in the solution is at a high concentration and the higher is the high temperature, but easily proceeds nucleation reaction, such Under such conditions, when the composite fiber is produced, the nuclei are difficult to be fixed to the cellulose fiber, and the inorganic particles liberated in the suspension are easily synthesized. Therefore, in order to produce a composite fiber in which hydrotalcite is tightly bound, it is necessary to appropriately control the nucleation reaction. Specifically, the optimization of CO ₃ ions and pulp concentration, by moderating the supply amount per unit time of the metal ions, this can be achieved. For example, CO ₃ ion concentration in the reaction vessel, preferably less than 0.01 mol / L or more 0.80 mol / L. If it is less than 0.01 mol / L, the reaction is difficult to proceed, and if it is 0.80 mol / L or more, inorganic particles liberated in the suspension are easily synthesized. The pulp concentration is preferably 0.5% or more and less than 4.0%. If it is less than 0.5%, the frequency of collision of the raw materials with the fibers decreases, so that the reaction does not proceed easily, and if it is 4.0% or more, a uniform composite cannot be obtained due to poor stirring. The amount of metal ions (cations) supplied per hour is determined by the balance with the concentration of anions in the reaction solution, and although it depends on the type of metal, for example, Mg ions and Al ions are added to CO ₃ ions and OH ions. If the the feed, the total concentration of CO ₃ ions and OH ions in the reaction solution (M; mol / L) and total supply amount of Mg ions and Al ions per minute for reaction 1L (mol / min · L) The ratio of is preferably 320: 1 or more. This is because when the amount of carbonate ion supplied is higher than 320: 1, nucleation is likely to proceed and inorganic particles liberated in the suspension are easily synthesized.

(Alumina / Silica)
When synthesizing alumina and / or silica, the method for synthesizing alumina and / or silica can be a known method. When any one or more of an inorganic acid or an aluminum salt is used as a starting material for the reaction, an alkaline silicate is added for synthesis. It is possible to synthesize by using an alkali silicate as a starting material and adding either one or more of an inorganic acid or an aluminum salt, but it is more produced when an inorganic acid and / or an aluminum salt is used as a starting material. Good fixation of substances to fibers. The inorganic acid is not particularly limited, and for example, sulfuric acid, hydrochloric acid, nitric acid and the like can be used. Of these, sulfuric acid is particularly preferable from the viewpoint of cost and handling. Examples of the aluminum salt include aluminum sulfate, aluminum chloride, polyaluminum chloride, alum, potassium alum and the like, and among them, the aluminum sulfate band can be preferably used. Examples of the alkali silicate include sodium silicate and potassium silicate, but sodium silicate is preferable because it is easily available. The molar ratio of silicic acid to alkali may be any, but generally, the one distributed as No. 3 silicic acid has a molar ratio of about SiO2: Na2O = 3 to 3.4: 1, and this can be preferably used. it can.

In the present invention, in producing a composite fiber in which silica and / or alumina is attached to the fiber surface, silica and / or alumina are synthesized on the fiber while maintaining the pH of the reaction solution containing the fiber at 4.6 or less. Is preferable. Although the details of the reason why a composite fiber having a well-coated fiber surface is obtained by this are not completely clarified, the ionization rate to trivalent aluminum ions is increased by keeping the pH low. It is considered that a composite fiber having a high coverage and fixing rate can be obtained.

In silica and / or alumina synthesis, the higher the concentration of raw materials (silicate ion, aluminum ion) in the reaction solution, and the higher the temperature condition, the easier the nucleation reaction proceeds. However, when producing composite fibers, Under such conditions, nuclei are less likely to be fixed to the cellulose fibers, and inorganic particles liberated in the suspension are likely to be synthesized. Therefore, in order to produce a composite fiber in which silica and / or alumina are tightly bound, it is necessary to appropriately control the nucleation reaction. Specifically, this can be achieved by optimizing the pulp concentration and gradual supply of silicate ions and aluminum ions to be added per hour. For example, the pulp concentration is preferably 0.5% or more and less than 4.0%. If it is less than 0.5%, the frequency of collision of the raw materials with the fibers decreases, so that the reaction does not proceed easily, and if it is 4.0% or more, a uniform composite cannot be obtained due to poor stirring. The amount of silicate ion and aluminum ion to be added per hour is preferably 1: 1. However, at this time, it is necessary to add an excess of Al ions in advance so as to maintain pH = 4.6 or less. When silicate ions are supplied at an excessive rate so as to exceed pH = 4.6, the inorganic particles composed of silica and / or alumina are difficult to settle on the pulp surface, and the inorganic particles released in the suspension are released. This is because it is easy to synthesize.

(Titanium oxide)
Titanium oxide composite fibers can be produced by synthesizing an inorganic binder in a slurry containing the fibers and titanium oxide.

By synthesizing the inorganic binder in the slurry containing the fiber and titanium oxide, the solid inorganic binder is fixed to the fiber and the titanium oxide is fixed to the inorganic binder. By this production method, a titanium oxide composite fiber in which titanium oxide is efficiently adhered to the fiber can be obtained.

For example, when the inorganic binder is hydrotalcite, a composite fiber of hydrotalcite, titanium oxide and fiber can be produced by synthesizing hydrotalcite in a solution containing fiber and titanium oxide.

The method for synthesizing hydrotalcite can be a known method. For example, first, the fibers are immersed in a carbonate aqueous solution containing carbonate ions forming an intermediate layer and an alkaline aqueous solution (sodium hydroxide or the like) in a reaction vessel and suspended to form a slurry. Then, titanium oxide is added to the obtained alkaline slurry and dispersed. Next, an acid solution (a metal salt aqueous solution containing divalent metal ions and trivalent metal ions constituting the basic layer) is added to the alkaline slurry to which titanium oxide has been added, and the coprecipitation reaction is performed by controlling the temperature, pH, etc. Synthesizes hydrotalcite. Then, when hydrotalcite is formed on the fiber surface, titanium oxide dispersed in the slurry is incorporated into or adheres to the hydrotalcite. As a result, the titanium oxide present in the slurry can be efficiently and uniformly fixed to the fibers at a high ratio.

The slurry obtained by immersing and suspending the fibers is preferably adjusted so that the pH is in the range of 11 to 14, more preferably in the range of 12 to 13. When the pH of the slurry is in this range, the titanium oxide to be added next can be uniformly dispersed in the slurry.

Further, as a source of divalent metal ions constituting the basic layer, various chlorides, sulfides, glass oxides and sulfates of magnesium, zinc, barium, calcium, iron, copper, silver, cobalt, nickel and manganese are used. be able to. Further, as a source of trivalent metal ions constituting the basic layer, various chlorides, sulfides, glass oxides and sulfates of aluminum, iron, chromium and gallium can be used.

Further, for example, when the inorganic binder is another metal compound, similarly, a composite fiber of the metal compound, titanium oxide and the fiber is produced by synthesizing the metal compound in a solution containing the fiber and titanium oxide. Can be done.

The method for synthesizing the metal compound is not particularly limited, and the metal compound can be synthesized by a known method, and may be either a gas-liquid method or a liquid-liquid method. As an example of the gas-liquid method, there is a carbon dioxide gas method. For example, magnesium carbonate can be synthesized by reacting magnesium hydroxide with carbon dioxide gas. In addition, calcium carbonate can be synthesized by the carbon dioxide gas method in which calcium hydroxide and carbon dioxide gas are reacted. For example, calcium carbonate may be synthesized by a soluble salt reaction method, a lime-soda method, or a soda method. Examples of the liquid-liquid method include reacting an acid (hydrochloric acid, sulfuric acid, etc.) with a base (sodium hydroxide, potassium hydroxide, etc.) by neutralization, reacting an inorganic salt with an acid or base, or combining inorganic salts with each other. Examples include a method of reacting. For example, barium sulfate can be obtained by reacting barium hydroxide with sulfuric acid. Aluminum hydroxide can be obtained by reacting aluminum chloride or aluminum sulfate with sodium hydroxide. By reacting calcium carbonate and aluminum sulfate, an inorganic binder in which calcium and aluminum are compounded can be obtained.

Further, when synthesizing the inorganic binder in this way, any further metal or metal compound different from titanium oxide can coexist in the reaction solution, and in this case, these metals or metal compounds are also inorganic. It can be efficiently incorporated into the binder and compounded.

Further, in the case of compounding two or more kinds of inorganic binders into a fiber, a step of synthesizing one kind of inorganic binder in the presence of the fiber and titanium oxide is performed, and then a step of synthesizing another kind of inorganic binder. , And if they do not interfere with each other's synthesis reaction or if a plurality of types of target inorganic binders are synthesized in one synthesis reaction, two or more types of inorganic binders may be synthesized at the same time.

When producing the composite fiber, various known auxiliaries can be further added. Such an additive can be added in an amount of 0.001% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, based on the inorganic binder.

The temperature of the synthesis reaction of the inorganic binder can be, for example, 30 ° C. or higher and 100 ° C. or lower, preferably 40 ° C. or higher and 80 ° C. or lower, more preferably 50 ° C. or higher and 70 ° C. or lower, and particularly preferably about 60 ° C. .. If the temperature is too high or too low, the reaction efficiency tends to decrease and the cost tends to increase.

Furthermore, the synthetic reaction can be controlled by the reaction time, and specifically, the time during which the reaction product stays in the reaction vessel can be adjusted and controlled. In addition, in the present invention, the reaction can be controlled by stirring the reaction solution in the reaction vessel or by making the neutralization reaction a multi-step reaction.

(fiber)
The composite used in the present invention is preferably a composite of cellulose fibers and inorganic particles. As the cellulose fibers constituting the composite, for example, not only natural cellulose fibers but also regenerated fibers (semi-synthetic fibers) such as rayon and lyocell and synthetic fibers can be used without limitation. Examples of raw materials for cellulose fibers include pulp fibers (wood pulp and non-wood pulp), cellulose nanofibers, bacterial cellulose, animal-derived cellulose such as squirrel, and algae. Wood pulp is produced by pulping wood raw materials. Just do it. Wood raw materials include red pine, black pine, todo pine, spruce, beni pine, larch, fir, tsuga, sugi, hinoki, larch, white pine, spruce, hiba, douglas fur, hemlock, white fur, spruce, balsam fur, cedar, pine, Conifers such as Merck pine and Radiata pine, and their mixtures, beech, hippo, hannoki, nara, tab, shii, white hippopotamus, larch, poplar, fir, doroyanagi, eucalyptus, mangrove, lauan, acacia and other broad-leaved trees and their mixture. The material is exemplified.

The method of pulping a natural material such as a wood raw material (wood raw material) is not particularly limited, and a pulping method generally used in the paper industry is exemplified. Wood pulp can be classified by the pulping method, for example, chemical pulp that has been vaporized by methods such as the craft method, sulfite method, soda method, and polysulfide method; mechanical pulp obtained by pulping by mechanical force such as a refiner and grinder; chemicals. Examples thereof include semi-chemical pulp; used paper pulp; and deinked pulp obtained by pulping by mechanical force after pretreatment with. The wood pulp may be in an unbleached (before bleaching) state or in a bleached (after bleaching) state.

Examples of non-wood-derived pulp include cotton, hemp, sisal, Manila hemp, flax, straw, bamboo, bagasse, kenaf, sugar cane, corn, rice straw, kozo, and mitsumata.

The pulp fiber may be unbeaten or beaten, and may be selected according to the physical properties of the composite sheet, but beating is preferable. This can be expected to improve the sheet strength and promote the fixation of inorganic particles.

Further, these cellulose raw materials are further treated to carry out powdered cellulose, chemically modified cellulose such as oxidized cellulose, and fine cellulose: cellulose nanofibers (CNF, TEMPO oxide CNF, phosphate esterified CNF, carboxymethylated CNF, mechanically pulverized. It can also be used as (CNF, etc.), microfibrillated cellulose (MFC).

The powdered cellulose used in the present invention has a constant particle size having a rod-like shape, which is produced by, for example, purifying and drying an undecomposed residue obtained after acid-hydrolyzing selected pulp, pulverizing and sieving. A crystalline cellulose powder having a distribution may be used, or commercially available products such as KC Flock (manufactured by Nippon Paper Co., Ltd.), Theoras (manufactured by Asahi Kasei Chemicals), and Abyssel (manufactured by FMC) may be used. The degree of polymerization of cellulose in powdered cellulose is preferably about 100 to 1500, the degree of crystallinity of powdered cellulose by X-ray diffraction is preferably 70 to 90%, and the volume average particle diameter by a laser diffraction type particle size distribution measuring device. Is preferably 1 μm or more and 100 μm or less. The cellulose oxide used in the present invention can be obtained by oxidizing in water with an oxidizing agent in the presence of, for example, an N-oxyl compound and a compound selected from the group consisting of bromide, iodide or a mixture thereof. it can.

Fine cellulose is a fiber obtained by defibrating a cellulosic raw material such as pulp. In the present invention, the average fiber diameter is a length-weighted average fiber diameter, and the average fiber length is a length-weighted average fiber length, which can be measured by, for example, a fractionator manufactured by Valmet Co., Ltd.

Fine cellulose includes cellulose nanofibers (hereinafter, also referred to as “CNF”) having an average fiber diameter of less than 500 nm, and microfibril cellulose fibers (hereinafter, also referred to as “MFC”).

(1) CNF / MFC
CNF / MFC is a single microfibril of cellulose, and its average fiber diameter is preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 30 nm or less. The average fiber length is preferably about 1 μm or more and 5 μm or less. In the present invention, when an aqueous dispersion having a concentration of 1% (w / v) (that is, an aqueous dispersion containing 1 g of CNF / MFC (dry weight) in 100 mL of water) is used, it is 100 mPa · s or more and 10,000 mPa · s or less. It is preferable to use a CNF / MFC that gives a B-type viscosity (60 rpm, 20 ° C.). The average fiber diameter and average fiber length of CNF can also be measured using an atomic force microscope (AFM) or a transmission electron microscope (TEM).

The B-type viscosity of the aqueous dispersion of CNF / MFC can be measured by a known method. For example, it can be measured using a VISCOMETER TV-10 viscometer manufactured by Toki Sangyo Co., Ltd. The temperature at the time of measurement is 20 ° C., and the rotation speed of the rotor is 60 rpm. In general, the CNF / MFC aqueous dispersion has thixotropic properties, and has the property that the viscosity decreases when agitated and shear stress is applied, and the viscosity increases and gels when left to stand. Therefore, the solution is sufficiently agitated. It is preferable to measure the B-type viscosity in this state.

The average aspect ratio of CNF / MFC is preferably 10 or more, more preferably 30 or more. The upper limit is not particularly limited, but is preferably 1000 or less, more preferably 100 or less, and even more preferably 80 or less. The average aspect ratio can be calculated by the following formula.
The average aspect ratio = average fiber length / average fiber diameter CNF / MFC is preferably a mechanically defibrated chemically modified CNF / MFC obtained by chemically denaturing pulp and then mechanically defibrating it. As described above, CNF / MFC has a different degree of defibration from the cellulosic raw material. It is generally not easy to quantify the degree of defibration, but in the present invention, it is possible to quantify the degree of defibration by the amount of change in the degree of drainage and water retention before and after mechanical defibration of CNF / MFC. I found that. The mechanically defibrated chemically modified cellulose fiber of the present invention is preferably obtained by mechanically defibrating or beating to such an extent that the drainage degree (F0) of the chemically modified pulp before defibration is reduced by 10 ml or more. That is, assuming that the degree of drainage after the treatment is F, the difference ΔF = F0-F in the degree of drainage is preferably 10 ml or more, more preferably 20 ml or more, and further preferably 30 ml or more. The degree of drainage of chemically modified pulp differs depending on the degree of denaturation, but since the degree of drainage of chemically modified pulp used as a raw material is used as a reference, the degree of defibration is determined regardless of the degree of chemical denaturation. Can be identified. As described above, since F0 differs depending on the degree of modification of the chemically modified pulp, it is difficult to unambiguously determine the upper limit of ΔF, but the drainage degree F after treatment is preferably larger than 0 ml. Since strong mechanical defibration is required to obtain CNF / MFC having an F of 0 ml, the MFC thus obtained may have an average fiber diameter of less than 500 nm (cellulose nanofibers). Further, when a large amount of CNF / MFC having a drainage degree of 0 ml is added to the papermaking process, the drainage of the pulp slurry used for papermaking may be deteriorated. The fibrilization rate of MFC determined by a fractionator manufactured by Valmet Co., Ltd. is preferably 3.5% or more, and more preferably 4% or more.

(2) Addition amount The addition amount of the fine cellulose is adjusted so as to be a desired amount with respect to the raw material pulp in the paper after papermaking. The amount with respect to the raw material pulp is preferably 20% by weight or less, more preferably 10% by weight or less, still more preferably 5% by weight or less with respect to the raw material pulp. If the amount added exceeds the upper limit, the water retention is too high, which may worsen the drainage during papermaking and reduce economic efficiency. The lower limit of the amount of fine cellulose added is not limited as long as the effect of the present invention can be obtained, but is adjusted as described above. The lower limit of the amount with respect to the raw material pulp is preferably about 1 ppm by weight or more, and more preferably 3 ppm by weight or more.

(3) Production of Fine Cellulose (3-1) Cellulose-based Raw Material Fine cellulose can be produced by chemically modifying a cellulosic raw material as necessary and then defibrating or beating. The cellulosic raw material is not particularly limited, and examples thereof include those derived from plants, animals (for example, ascidians), algae, microorganisms (for example, acetobacter), and microbial products. Plant-derived materials include, for example, wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (conifer unbleached kraft pulp (NUKP), conifer bleached kraft pulp (NBKP), broadleaf unbleached kraft pulp (NBKP). LUKP), broadleaf bleached kraft pulp (LBKP), conifer unbleached sulphite pulp (NUSP), conifer bleached sulphite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, used paper, etc.). The cellulose raw material used in the present invention may be any one or a combination of these, but is preferably a cellulosic fiber derived from a plant or a microorganism, and more preferably a cellulose fiber derived from a plant.

(3-2) Chemical modification Chemical modification refers to the introduction of a functional group into a cellulosic raw material, and in the present invention, it is preferable to introduce an anionic group. Examples of the anionic group include an acid group such as a carboxyl group, a carboxyl group-containing group, a phosphoric acid group, and a phosphoric acid group-containing group. Examples of the carboxyl group-containing group include -COOH group, -R-COOH (R is an alkylene group having 1 or more and 3 or less carbon atoms), and -OR-COOH (R is an alkylene group having 1 or more and 3 or less carbon atoms). Can be mentioned. Examples of the phosphoric acid group-containing group include a polyphosphoric acid group, a phosphorous acid group, a phosphonic acid group, and a polyphosphoric acid group. Depending on the reaction conditions, these acid groups may be introduced in the form of salts (for example, carboxylate groups (-COOM, M is a metal atom)). In the present invention, the chemical modification is preferably oxidation or etherification.

Oxidation can be carried out as known. For example, a method of oxidizing a cellulose raw material in water using an oxidizing agent in the presence of an N-oxyl compound and a substance selected from the group consisting of bromide, iodide and a mixture thereof can be mentioned. According to this method, the primary hydroxyl group at the C6 position of the glucopyranose ring on the surface of cellulose is selectively oxidized to generate a group selected from the group consisting of an aldehyde group, a carboxyl group, and a carboxylate group. Alternatively, an ozone oxidation method can be mentioned. According to this oxidation reaction, the hydroxyl groups at at least the 2nd and 6th positions of the glucopyranose ring constituting the cellulose are oxidized, and the cellulose chain is decomposed.

An example of a method for measuring the amount of carboxyl groups will be described below. Prepare 60 mL of a 0.5 wt% slurry (aqueous dispersion) of cellulose oxide, add a 0.1 M hydrochloric acid aqueous solution to adjust the pH to 2.5, and then add a 0.05 N sodium hydroxide aqueous solution to bring the pH to 11. Measure the electrical conductivity until it becomes. 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 electrical conductivity is gradual, using the following formula.
Amount of carboxyl groups [mmol / g cellulose oxide] = a [mL] x 0.05 / weight of cellulose oxide [g]

The amount of carboxyl groups in the cellulose oxide measured in this way is preferably 0.1 mmol / g or more, more preferably 0.5 mmol / g or more, still more preferably 0.8 mmol / g, based on the absolute dry weight. That is all. The upper limit of the amount is preferably 3.0 mmol / g or less, more preferably 2.5 mmol / g or less, and further preferably 2.0 mmol / g or less. Therefore, the amount is preferably 0.1 mmol / g or more and 3.0 mmol / g or less, more preferably 0.5 mmol / g or more and 2.5 mmol / g or less, and further preferably 0.8 mmol / g or more and 2.0 mmol / g or less. preferable.

As etherification, carboxymethyl (ether), methyl (ether), ethyl (ether), cyanoethyl (ether), hydroxyethyl (ether), hydroxypropyl (ether), ethylhydroxyethyl (ether) And hydroxypropylmethyl (ether) conversion. Of these, carboxymethylation is preferable. Carboxymethylation can be carried out, for example, by a method in which a cellulose raw material as a bottoming material is marcelled and then etherified.

The degree of carboxymethyl substitution per glucose unit of carboxymethylated cellulose is measured by, for example, the following method. That is, 1) About 2.0 g of carboxymethylated cellulose (absolutely dried) is precisely weighed and placed in an Erlenmeyer flask with a 300 mL stopper. 2) Add 100 mL of a solution prepared by adding 100 mL of special grade concentrated nitric acid to 1000 mL of methanol nitrate, and shake for 3 hours to change the carboxymethyl cellulose salt (carboxymethylated cellulose) into hydrogen-type carboxymethylated cellulose. 3) Weigh 1.5 g or more and 2.0 g or less of hydrogen-type carboxymethylated cellulose (absolutely dry), and put them in an Erlenmeyer flask with a 300 mL stopper. 4) Wet hydrogen-type carboxymethylated cellulose with 15 mL of 80% methanol, add 100 mL of 0.1 N NaOH, and shake at room temperature for 3 hours. 5) Using phenolphthalein as an indicator, back titrate excess NaOH with 0.1 N H ₂ SO ₄ . 6) Calculate the degree of carboxymethyl substitution (DS) by the following formula:
A = [(100 x F'-(0.1 N H ₂ SO ₄ ) (mL) x F) x 0.1] / (absolute dry mass (g) of hydrogen-type carboxymethylated cellulose)
DS = 0.162 × A / (1-0.058 × A)
A: 1N NaOH amount (mL) required to neutralize 1 g of hydrogen-type carboxymethylated cellulose
F: 0.1N H ₂ SO ₄ factor F': 0.1N NaOH factor

The degree of carboxymethyl substitution per anhydrous glucose unit in carboxymethylated cellulose is preferably 0.01 or more, more preferably 0.05 or more, still more preferably 0.10 or more. The upper limit of the degree of substitution is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.35 or less. Therefore, the degree of carboxymethyl group substitution is preferably 0.01 or more and 0.50 or less, more preferably 0.05 or more and 0.40 or less, and further preferably 0.10 or more and 0.30 or less.

(3-3) Defibering or beating A fine cellulose can be produced by mechanically defibrating or beating cellulose, and a chemically modified fine cellulose can be produced by mechanically defibrating or beating chemically modified cellulose. The defibration or beating treatment may be performed once, or these may be performed individually or in combination multiple times. In the case of a plurality of times, the time of each defibration or beating may be any time, and the devices used may be the same or different.

The device used for the defibration or beating process is not particularly limited, and examples thereof include high-speed rotary type, colloid mill type, high-pressure type, roll mill type, ultrasonic type, and high-pressure or ultra-high pressure homogenizer, refiner, and the like. A beater, a PFI mill, a kneader, a disperser or the like in which a metal or a blade and a pulp fiber act on each other around a rotation axis, or a material due to friction between pulp fibers can be used.

The fibers shown above may be used alone or in combination of two or more. For example, the fibrous substance recovered from the wastewater of a paper mill may be supplied to the carbonation reaction of the present invention. By supplying such a substance to the reaction vessel, various composite particles can be synthesized, and fibrous particles and the like can be synthesized in terms of shape.

In the present invention, in addition to fibers, a substance that is incorporated into inorganic particles as a product to form composite particles can be used. In the present invention, fibers such as pulp fibers are used, but in addition to these, these substances are further incorporated by synthesizing inorganic particles in a solution containing inorganic particles, organic particles, polymers and the like. It is possible to produce composite particles.

The fiber length of the composited fiber is not particularly limited, but for example, the average fiber length can be about 0.1 μm to 15 mm, and may be 10 μm to 12 mm, 50 μm to 10 mm, 200 μm to 8 mm, or the like. Of these, in the present invention, it is preferable that the average fiber length is longer than 50 μm because dehydration and sheet formation are easy. It is more preferable that the average fiber length is longer than 200 μm because dehydration and sheeting can be performed by using a mesh of a wire (filter) for dehydration and / or papermaking used in a normal papermaking process.
The fiber diameter of the fiber to be composited is not particularly limited, but for example, the average fiber diameter can be about 1 nm to 100 μm, 10 nm to 100 μm, 0.15 μm to 100 μm, 1 μm to 90 μm, 3 to 50 μm, 5 to 30 μm. And so on. Of these, in the present invention, it is preferable that the average fiber diameter is higher than 500 nm because water and sheet formation are easy. It is more preferable that the average fiber diameter is higher than 1 μm because dehydration and / or papermaking wire (filter) mesh used in a normal papermaking process can be used for dehydration and sheet formation.

6. Step 3: Selection step This step is an indispensable step for removing inorganic particles and impurities that have not been composited with the fiber to obtain a highly pure composite. These can be carried out by a known process, and may be appropriately determined in consideration of the application, energy efficiency and the like. There is no particular limitation on the type of filter or dehydrator, and general ones can be used. For example, the concentration / desolving treatment is a centrifugal dehydrator (centrifuge) which is a filtration type dehydration. ), A vacuum dehydrator, a pressurized dehydrator, a sedimentation concentrated dehydrator, etc. Specifically, centrifuge type: Tanabe Wiltec centrifuge, Kokusan centrifuge, decanter, screw decanter, etc. Vacuum dehydration type: Drum type vacuum dehydrator, Sysxiner, Tsukishima Kikai horizontal belt Pressurized dehydration type such as filter, Oliver filter, etc .: Filter press, roll press, tube press, screw press, belt press Horizontal belt filter, polydisc filter, screen, pelletizer, etc. can be mentioned. Further, a plurality of these can be used in combination.

By providing the selection process, the apparent volume and weight of the composite can be increased, and transportation and handling become easier. Further, when the filter is subjected to a selection method for separating the filtrate as in the filtration method, it is possible to remove by-products during synthesis represented by inorganic salts.

In the selection step, the suspension of the composite of the inorganic substance and the fiber is selected so that the fine fibers and / or the inorganic particles of 140 mesh pass measured according to the pulp sieving test method of JIS P 8207 are 50% or less. Is preferable.

Further, in the selection step, the solid content concentration of the complex may be improved, that is, concentrated. In the case of concentration, the concentration of the complex slurry before concentration is 0.1 to 20%, whereas the concentration concentration of the complex may be determined according to the application, for example, 0.5 to 40%. , 1-35%, 2-30%, 3-25% and the like.

In the present invention, if necessary, processing such as storage in a storage tank, crushing, classification, aging, and dispersion can be performed. These can be carried out by a known process, and may be appropriately determined in consideration of the application, energy efficiency and the like. For example, as a crushing method, a ball mill, a sand grinder mill, an impact mill, a high pressure homogenizer, a low pressure homogenizer, a dyno mill, an ultrasonic mill, a kanda grinder, an attritor, a stone mill, a vibration mill, a cutter mill, a jet mill, a breaker, Examples thereof include a beating machine, a short-screw extruder, a twin-screw extruder, an ultrasonic stirrer, and a household juicer mixer. As a classification method, a sieve such as a mesh, an outward type or inward type slit, an outward type or inward type round hole screen, a vibration screen, a heavy foreign matter cleaner, a lightweight foreign matter cleaner, a reverse cleaner, and a sieving test Machines, etc. can be mentioned. Examples of the dispersion method include a high-speed disperser and a low-speed kneader.

Further, in the present invention, since the complex which is a reaction product is obtained as a suspension, it can be stored in a storage tank or treated by concentration, desolvation, pulverization, classification, aging, dispersion and the like, if necessary. It can be performed.

The composite obtained by the present invention can be blended with a filler or a pigment in a suspension state without completely removing the solvent, but it can also be dried into a powder. The dryer in this case is also not particularly limited, but for example, an air flow dryer, a band dryer, a spray dryer, or the like can be preferably used.

The complex obtained by the present invention can be modified by a known method. For example, in some embodiments, the surface can be made hydrophobic to enhance miscibility with resins and the like.

7. Composite The composite obtained by the present invention can be used for various purposes, for example, paper, fiber, cellulose-based composite material, filter material, paint, plastic or other resin, rubber, elastomer, ceramic, glass. , Tires, building materials (asphalt, asbestos, cement, boards, concrete, bricks, tiles, plywood, fiberboards, ceiling materials, wall materials, floor materials, roofing materials, etc.), furniture, automobile parts, various carriers (catalyst carriers, etc.) , Pharmaceutical carriers, pesticide carriers, microbial carriers, etc.), excipients (purification of impurities, deodorization, dehumidification, etc.), anti-wrinkle agents, clay, abrasives, friction materials, modifiers, repair materials, heat insulating materials, heat resistant materials, Heat-dissipating material, moisture-proof material, water-repellent material, water-resistant material, light-shielding material, sealant, shield material, insect repellent, adhesive, ink, cosmetics, medical material, paste material, discoloration inhibitor, food additive, tablet excipient , Dispersant, shape-retaining agent, water-retaining agent, filtration aid, refined oil material, oil treatment agent, oil modifier, radio wave absorber, insulating material, sound insulation material, vibration isolator, semiconductor encapsulant, radiation blocking material, It can be widely used in all applications such as cosmetics, fertilizers, feeds, fragrances, additives for paints and adhesives, flame-retardant materials, sanitary products (disposable diapers, sanitary napkins, incontinence pads, breast milk pads, etc.) .. Further, it can be used as various fillers, coating agents and the like in the above-mentioned applications.

The composite obtained by the present invention may be applied to papermaking applications, for example, printing paper, newspaper, inkjet paper, PPC paper, kraft paper, high-quality paper, coated paper, finely coated paper, wrapping paper, thin leaf paper. , Color quality paper, cast coated paper, non-carbon paper, label paper, heat sensitive paper, various fancy papers, water-soluble paper, release paper, process paper, wallpaper base paper, non-combustible paper, flame-retardant paper, laminated board base paper, printed electronics Paper, battery separator, cushion paper, tracing paper, impregnated paper, ODP paper, building material paper, decorative paper, envelope paper, tape paper, heat exchange paper, synthetic fiber paper, sterilized paper, water resistant paper, oil resistant paper, heat resistant Paper, photocatalyst paper, decorative paper (greasy paper, etc.), various sanitary papers (toilet paper, tissue paper, wipers, diapers, sanitary goods, etc.), tobacco paper, paperboard (liner, core base paper, white paperboard, etc.), paper plates Examples include base paper, cup base paper, baking paper, abrasive paper, and synthetic paper. That is, according to the present invention, a composite of an inorganic substance having a small primary particle size and a narrow particle size distribution and a fiber can be obtained, which is different from the conventional inorganic filler having a particle size of more than 2 μm. The characteristics can be exhibited. Furthermore, unlike the case where the inorganic substance is simply blended with the fiber, if the inorganic substance is complexed with the fiber, not only the inorganic substance can be easily yielded to the sheet, but also a sheet in which the inorganic substance is uniformly dispersed without agglomeration can be obtained. it can. It has been clarified from the results of electron microscope observation that the inorganic substance in the present invention is not only fixed on the outer surface of the fiber and inside the lumen, but also formed on the inside of the microfibril in a preferable embodiment.

Further, when the composite obtained by the present invention is used, particles generally called inorganic fillers and organic fillers and various fibers can be used in combination. For example, as an inorganic filler, calcium carbonate (light calcium carbonate, heavy calcium carbonate), magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, clay (kaolin, calcined kaolin, deramikaolin). ), Tarku, zinc oxide, zinc stearate, titanium dioxide, silica made from sodium silicate and mineral acid (white carbon, silica / calcium carbonate complex, silica / titanium dioxide complex), white clay, bentonite, diatomaceous clay, Examples thereof include calcium sulfate, zeolite, an inorganic filler that regenerates and utilizes ash obtained from the deinking process, and an inorganic filler that forms a complex with silica or calcium carbonate in the process of regeneration. As the calcium carbonate-silica composite, amorphous silica such as white carbon may be used in combination with the calcium carbonate and / or the light calcium carbonate-silica composite. Organic fillers include urea-formalin resin, polystyrene resin, phenolic resin, microhollow particles, acrylamide composites, wood-derived substances (fine fibers, microfibril fibers, powdered kenaf), modified insolubilized starch, ungelatinized starch, etc. Can be mentioned. The fibers include not only natural fibers such as cellulose, but also synthetic fibers artificially synthesized from raw materials such as petroleum, recycled fibers (semi-synthetic fibers) such as rayon and lyocell, and inorganic fibers without limitation. Can be used. In addition to the above, natural fibers include protein fibers such as wool, silk thread and collagen fibers, and composite sugar chain fibers such as chitin / chitosan fibers and alginate fibers. Examples of the cellulose-based raw material include pulp fibers (wood pulp and non-wood pulp), bacterial cellulose, animal-derived cellulose such as squirrel, and algae. Wood pulp may be produced by pulping the wood raw material. Wood raw materials include red pine, black pine, todo pine, spruce, beni pine, larch, fir, tsuga, sugi, hinoki, larch, white pine, spruce, hiba, douglas fur, hemlock, white fur, spruce, balsam fur, cedar, pine, Conifers such as Merck pine and Radiata pine, and their mixtures, beech, hippo, hannoki, nara, tab, shii, white hippopotamus, larch, poplar, fir, doroyanagi, eucalyptus, mangrove, lauan, acacia and other broad-leaved trees and their mixture. The material is exemplified. The method for pulping a wood raw material is not particularly limited, and a pulping method generally used in the paper industry is exemplified. Wood pulp can be classified by the pulping method, for example, chemical pulp that has been vaporized by methods such as the craft method, sulfite method, soda method, and polysulfide method; mechanical pulp obtained by pulping by mechanical force such as a refiner and grinder; chemicals. Examples thereof include semi-chemical pulp; used paper pulp; and deinked pulp obtained by pulping by mechanical force after pretreatment with. The wood pulp may be in an unbleached (before bleaching) state or in a bleached (after bleaching) state. Examples of non-wood-derived pulp include cotton, hemp, sisal, Manila hemp, flax, straw, bamboo, bagasse, kenaf, sugar cane, corn, rice straw, kozo, and mitsumata. The wood pulp and non-wood pulp may be either unbeaten or beaten. Further, these cellulose raw materials are further treated to carry out powdered cellulose, chemically modified cellulose such as oxidized cellulose, and cellulose nanofibers: CNF (microfibrillated cellulose: MFC, TEMPO oxide CNF, phosphate esterified CNF, carboxymethylation). It can also be used as CNF, machine crushed CNF). Examples of synthetic fibers include polyester, polyamide, polyolefin and acrylic fibers, examples of semi-synthetic fibers include rayon and acetate, and examples of inorganic fibers include glass fibers, carbon fibers and various metal fibers. Regarding the above, these may be used alone or in combination of two or more types.

The composite obtained by the present invention can also be processed into various molded products (body). For example, it can be processed into powders, pellets, molds, aqueous suspensions, pastes, sheets and other shapes. Further, the composite may be used as a main component to form a molded product such as a mold or particles / pellets together with other materials. The dryer for drying into powder is not particularly limited, but for example, an air flow dryer, a band dryer, a spray dryer, and the like can be preferably used.

For example, when the composite obtained by the present invention is made into a sheet, a sheet having a high ash content can be easily obtained. Further, the obtained sheets can be laminated to form a multi-layer sheet. Examples of the paper machine (paper machine) used for sheet production include a long net paper machine, a round net paper machine, a gap former, a hybrid former, a multi-layer paper machine, and a known paper machine that combines the paper making methods of these devices. Be done. The press line pressure in the paper machine and the calendar line pressure in the case of performing the calendar processing in the subsequent stage can be set within a range that does not hinder the operability and the performance of the composite sheet. Further, starch, various polymers, pigments and mixtures thereof may be applied to the formed sheet by impregnation or coating.

A wet and / or dry paper strength agent (paper strength enhancer) can be added at the time of sheet formation. Thereby, the strength of the composite sheet can be improved. Examples of paper strength agents include urea formaldehyde resin, melamine formaldehyde resin, polyamide, polyamine, epichlorohydrin resin, vegetable gum, latex, polyethyleneimine, glyoxal, gum, mannogalactan polyethyleneimine, polyacrylamide resin, and polyvinylamine. , Polyvinyl alcohol and the like; composite polymers or copolymers composed of two or more kinds selected from the above resins; starches and processed starches; carboxymethyl cellulose, guar gum, urea resins and the like. The amount of the paper strength agent added is not particularly limited.

In addition, a high molecular polymer or an inorganic substance can be added in order to promote the fixation of the filler to the fiber and to improve the yield of the filler and the fiber. For example, as a coagulant, polyethyleneimine and modified polyethyleneimine containing a tertiary and / or quaternary ammonium group, polyalkyleneimine, dicyandiamide polymer, polyamine, polyamine / epiclohydrin polymer, and dialkyldialyl quaternary ammonium monomer, dialkyl. Aminoalkyl acrylates, dialkylaminoalkylmethacrylates, dialkylaminoalkylacrylamides, dialkylaminoalkylmethacrylate and acrylamide polymers, polymers consisting of monoamines and epihalohydrins, polymers with polyvinylamine and vinylamine moieties, and cations such as mixtures thereof. In addition to the sex polymer, a cation-rich amphoteric polymer in which an anionic group such as a carboxyl group or a sulfone group is copolymerized in the molecule of the polymer, or a mixture of a cationic polymer and an anionic or amphoteric polymer is used. be able to. Further, as the retention agent, a cationic or anionic or amphoteric polyacrylamide-based substance can be used. In addition to these, a yield system called a so-called dual polymer, in which at least one or more cation or anionic polymers are used in combination, can be applied, and at least one or more anionic bentonite, colloidal silica, polysilicic acid, etc. can be applied. It is a multi-component yield system that uses one or more of inorganic fine particles such as polysilicic acid or polysilicate microgels and their aluminum modifiers, and organic fine particles with a particle size of 100 μm or less, which are so-called micropolymers cross-linked and polymerized with acrylamide. May be good. In particular, when the polyacrylamide-based substance used alone or in combination has a weight average molecular weight of 2 million daltons or more by the ultimate viscosity method, a good yield can be obtained, preferably 5 million daltons or more, more preferably. Can obtain a very high yield when it is the above-mentioned acrylamide-based substance of 10 million daltons or more and less than 30 million daltons. The form of this polyacrylamide-based substance may be an emulsion type or a solution type. The specific composition is not particularly limited as long as the substance contains an acrylamide monomer unit as a structural unit, and is, for example, a copolymer of a quaternary ammonium salt of an acrylic acid ester and acrylamide, or acrylamide. Acrylic acid ester is copolymerized with and then quaternized ammonium salt. The cationic charge density of the cationic polyacrylamide-based substance is not particularly limited.

In addition, depending on the purpose, inorganic particles such as drainage improver, internal sizing agent, pH adjuster, defoamer, pitch control agent, slime control agent, bulking agent, calcium carbonate, kaolin, talc, silica, etc. (so-called) Filling fee) and the like. The amount of each additive used is not particularly limited.

It is also possible to use a molding method other than sheeting. For example, a method called pulp molding in which a raw material is poured into a mold for suction dehydration and drying, or a method of spreading and drying on the surface of a molded product such as resin or metal. After that, molded products having various shapes can be obtained by a method of peeling from the base material or the like. Further, it can be molded into a plastic by mixing a resin, or it can be molded into a ceramic by adding a mineral such as silica or alumina and firing it. In the compounding / drying / molding shown above, only one type of composite may be used, or two or more types of composites may be mixed and used. When two or more kinds of composites are used, those which are mixed in advance can be used, or those which are mixed, dried and molded by each can be mixed later.

In addition, various organic substances such as polymers and various inorganic substances such as pigments may be added to the molded product of the composite later.

Hereinafter, a method for producing a composite having a preparation step, a reaction step, a concentration step, and a molding step will be described with reference to the following examples.

[Example 1]
A sheet of softwood bleached kraft pulp (NBKP, manufactured by Nippon Paper Industries, Ltd.) was dissolved in water with a pulper (manufactured by IHI voice) at a concentration of 5% to prepare a pulp dispersion. This was beaten with a double disc refiner (DDR, manufactured by Aikawa Iron Works Co., Ltd.) until the degree of drainage reached 500 ml. The obtained pulp dispersion is passed through a screen (manufactured by Aikawa Iron Works) to remove foreign substances, and then 10 m ³ is poured into a reactor (manufactured by Sumitomo Heavy Industries Process Equipment Co., Ltd.), and sodium hydroxide is stirred at a temperature of 50 ° C. And sodium carbonate were added at 75.3% and 12.5% by weight of the pulp to give pH 13. Then, a mixed solution of 9.7% zinc sulfate and 3.4% aluminum sulfate was added dropwise over 60 minutes and reacted until the pH reached 7. The suspension of the obtained complex was dehydrated to a concentration of 30% with a dehydrator (manufactured by Togoku Kogyo Co., Ltd.) to obtain a dehydrated cake of the complex. This was redistributed to a concentration of 0.5% and sheeted at a papermaking speed of 200 m / min with a Nagami paper machine to obtain a composite sheet.

[Example 2]
The NBKP sheet was dissolved in water at a concentration of 5% with a pulper (manufactured by Fuji Seisakusho Co., Ltd.) to prepare a pulp dispersion. This was beaten with a single disc refiner (SDR, manufactured by Kumagai Riki Co., Ltd.) until the degree of drainage reached 500 ml. After removing foreign substances by passing the obtained pulp dispersion through a high-concentration cleaner (manufactured by Aikawa Iron Works), slaked lime (calcium hydroxide: Ca (OH) ₂ , Okutama) using a reactor as shown in FIG. ), The reaction solution was circulated at a pump flow rate of 80 L / min using an ultrafine bubble generator (shear type, Envirovision YJ-9, Fig. 2) with respect to 2 m ³ of the 1% aqueous suspension (from the nozzle). Injection speed: 125 L / min · cm2). By blowing carbon dioxide gas from the air supply port of the ultrafine bubble generator, a large amount of ultrafine bubbles containing carbon dioxide gas was generated in the reaction solution, and calcium carbonate particles were synthesized by the carbon dioxide gas method. The reaction was carried out for 365 minutes at a reaction temperature of 15 ° C. and a carbon dioxide gas blowing amount of 16 L / min, and the reaction was stopped when the pH of the reaction solution reached 7.5 to obtain a sample (the pH before the reaction was 12.8). The average particle size of the ultrafine bubbles was about 137 nm, and the average time from the generation of the ultrafine bubbles to the disappearance of the ultrafine bubbles (also referred to as the existence time of the bubbles) was 60 minutes or more. The suspension of the obtained complex was dehydrated to a concentration of 25% with a dehydrator (manufactured by Tsukishima Machine Sales Co., Ltd.) to obtain a dehydrated cake of the complex. This was redistributed to a concentration of 0.5% and sheeted at a papermaking speed of 20 m / min with a Nagami paper machine to obtain a composite sheet.

[Example 3]
Softwood bleached kraft pulp (NBKP, 400 g, concentration 2%) was adjusted with Niagara Beater (manufactured by Kumagai Riki Co., Ltd.) until a Canadian standard drainage CSF: 215 mL. Calcium hydroxide 300g of them (slaked _{lime: Ca (OH) 2, 300g} , Wako Pure Chemical) was charged to aqueous suspensions 30L including. This aqueous suspension is placed in a 40 L cavitation device (Fig. 3), carbon dioxide gas is blown into the reaction vessel to generate cavitation, and composite fibers of calcium carbonate fine particles and fibers are synthesized by the carbon dioxide gas method. A sample was obtained. The reaction temperature was about 25 ° C., the carbon dioxide gas was supplied from a commercially available liquefied gas, the amount of carbon dioxide gas blown was 40 L / min, and the reaction was stopped when the pH of the reaction solution reached about 7 (before the reaction). The pH of is about 12.8). The suspension of the obtained complex was dehydrated to a concentration of 15% with a large centrifugal dehydrator (manufactured by Kumagai Riki Co., Ltd.) to obtain a dehydrated cake of the complex.

[Example 4]
Place 1060 mL of an aqueous suspension containing 6.5 g of polypropylene fiber (CSF adjusted to 824 mL by Niagara beater, raw polypropylene fiber is made of Toa Spinning Material, fiber length 6 mm) in a 2 L resin container and bring to 45 ° C. The mixture was stirred with a lab mixer while heating (500 rpm). An aqueous solution of aluminum sulfate (industrial sulfate band, about 2.7% in terms of alumina) was added dropwise to this aqueous suspension for about 2 minutes until pH = 3.7, and then an aqueous solution of aluminum sulfate (industrial sulfate band, alumina). In terms of conversion, about 2.7%, 40 g) and an aqueous sodium silicate solution (Wako Pure Chemical, concentration 5%, 122 g) were added dropwise simultaneously for about 80 minutes so as to maintain pH = 4. A Perister pump was used for dropping, and the reaction temperature was about 45 ° C. As described above, a composite of silica / alumina fine particles and polypropylene fibers was synthesized. The suspension of the obtained complex was dehydrated to a concentration of 20% with a large centrifugal dehydrator (manufactured by Kumagai Riki Co., Ltd.) to obtain a dehydrated cake of the complex.

Claims (15)

A method for producing a composite of an inorganic substance and a fiber, which comprises the following steps 1 to 3.
[Step 1] Step of dispersing fibers in a solvent
[Step 2] A step of adding a chemical to the fiber dispersion obtained in step 1 to form and react an inorganic substance and a fiber complex.
[Step 3] A step of carefully selecting a composite of an inorganic substance and a fiber from a suspension of the composite of the inorganic substance and the fiber obtained in the step 2. In [Step 3], the suspension of the composite of the inorganic substance and the fiber was carefully selected so that the fine fiber and / or the inorganic particle of 140 mesh pass measured according to the pulp sieving test method of JIS P 8207 was 50% or less. The method for producing a composite according to claim 1, which comprises the above. The method for producing a composite according to claim 1 or 2, wherein in [Step 2], an acid and / or an alkali is added to the dispersion of fibers obtained in Step 1 to adjust the pH to a desired value. .. The method for producing a composite according to any one of claims 1 to 3, which comprises molding the composite of the inorganic substance and the fiber from the suspension of the composite of the inorganic substance and the fiber obtained in step 3. The method for producing a composite according to any one of claims 1 to 4, wherein the fiber is any one or more of synthetic fiber, regenerated fiber, and natural fiber. The method for producing a complex according to any one of claims 1 to 5, wherein the solvent is any one or two or more of water and an organic solvent. The complex according to any one of claims 1 to 6, wherein at least a part of the inorganic substance is a metal salt of calcium, silicic acid, magnesium, zinc, barium, aluminum, or metal particles containing titanium, copper, magnesium, zinc. Manufacturing method. The chemicals according to claim 1 include sodium hydroxide, sodium carbonate, titanium oxide, sulfuric acid, aluminum sulfate, magnesium sulfate, calcium hydroxide, barium hydroxide, aluminum hydroxide, magnesium hydroxide, magnesium chloride, sodium silicate, and sulfuric acid. The method for producing a complex according to any one of claims 1 to 7, which comprises one or more of zinc, zinc chloride, copper sulfate, copper chloride, and carbon dioxide. The method for producing a composite according to any one of claims 1 to 8, wherein the step of beating the fibers is included before the step 2. The method for producing a composite according to any one of claims 1 to 9, wherein in the step 2, the fibers and chemicals are mixed using a stirrer. The method for producing a composite according to any one of claims 1 to 10, wherein in the step 2, the fibers and the chemicals are mixed by using circulation, circulation or jet flow by a pump. The method for producing a composite according to any one of claims 1 to 11, wherein the step 2 is a batch type or a continuous type. The composite according to any one of claims 1 to 12, wherein in the step 3, the suspension of the composite of the inorganic substance and the fiber is concentrated by using any of filtration type separation, sedimentation concentration, evaporation concentration, and pressure dehydration. How to make a body. The method for producing a composite according to any one of claims 1 to 13, wherein 5% or more of the fiber surface is coated with an inorganic substance. The method for producing a composite according to any one of claims 1 to 14, which is a composite in which an inorganic substance is self-fixed to fibers.

Images