JP6545329B2 - Fiber composite and method for producing the same - Google Patents

Description

  The present invention relates to a composite of silica or alumina and fibers and a method of producing the same.

  In general, calcium carbonate is produced by physically grinding and classifying natural limestone or weathered shells as a raw material, "natural calcium carbonate", and "synthetic calcium carbonate" produced by chemically reacting limestone as a raw material Light calcium carbonate). And as a synthetic method of synthetic calcium carbonate, carbon dioxide method, lime-soda method, soda method are known, and although lime-soda method and soda method are partly used for special applications, they are industrial The synthesis of calcium carbonate is generally carried out by the carbon dioxide method.

The synthesis of calcium carbonate by the carbon dioxide method is carried out by reacting quicklime with carbon dioxide gas, and in general, a quenching step to obtain slaked lime Ca (OH) ₂ by adding water to quicklime CaO, and carbon dioxide CO to slaked lime _B) blowing in ₂ to obtain calcium carbonate CaCO ₃ . Nowadays, various techniques for controlling the particle shape, particle size and the like of the product calcium carbonate have been proposed by controlling the reaction conditions of the synthesis step of calcium carbonate, particularly the carbonation step.

  Also, various techniques have been proposed for depositing calcium carbonate on fibers such as pulp. Patent Document 1 describes a complex in which crystalline calcium carbonate is mechanically bonded onto a fiber. In addition, Patent Document 2 describes a technique for producing a composite of pulp and calcium carbonate by depositing calcium carbonate in a pulp suspension by a carbon dioxide method. Patent Document 3 describes a method for improving the whiteness and cleanliness of waste paper fibers by adding a large amount of filler to fibers for paper and paperboard, sending a slurry of waste paper pulp to a gas-liquid contact device to flow In contrast, techniques have been described to apply the alkali salt slurry in the direction of flow to wick the pulp in the maceration zone and to feed the appropriate reactive gas and mix with the settling filler to deposit the filler on the fiber surface.

Unexamined-Japanese-Patent No. 06-158585 U.S. Patent No. 5,679,220 U.S. Pat. No. 5,665,205

  The present inventors are to develop a composite of silica or alumina and fibers and a method for producing the same.

  The present inventors have developed a complex of calcium carbonate fine particles and fibers, and by synthesizing silica or alumina while spraying a liquid in the presence of fibers, a complex of silica or alumina and fibers It has been found that the present invention can be manufactured efficiently.

That is, the present invention includes, but is not limited to, the following inventions.
(1) A method for producing a fiber composite, comprising synthesizing silica and / or alumina in the presence of fibers while injecting a liquid into a reaction vessel.
(2) The method according to (1), wherein silica and / or alumina are synthesized in the presence of cavitation bubbles.
(3) The method according to (1) or (2), which is synthesized using any one or more of an inorganic acid or an aluminum salt and an alkali silicate salt.
(4) The method according to any one of (1) to (3), which is synthesized using sulfuric acid or aluminum sulfate and sodium silicate.
(5) The method according to any one of (1) to (4), wherein the average primary particle diameter of silica and / or alumina on the fiber composite is 100 nm or less.
(6) The method in any one of (1)-(5) the said fiber is a pulp fiber.
(7) The method according to any one of (1) to (6), which comprises circulating the reaction solution and injecting it into the reaction vessel.

  According to the present invention, a composite of silica or alumina and fibers can be produced by synthesizing silica or alumina in the presence of fibers while spraying a liquid.

FIG. 1 is a schematic view showing a reactor used in an experimental example of the present invention. FIG. 2 is an electron micrograph (magnification: 200 times) of the surface microfibrillated hardwood pulp fiber (CV-treated pulp) used in Experiment 1. FIG. 3 is an electron micrograph of the cellulose nanofibers used in Experiment 1 (magnification: 200 ×). FIG. 4 is an electron micrograph of a complex of calcium carbonate fine particles synthesized in Experiment 1 and a fiber (CV-treated pulp) (magnification: left 10000 times, right 50,000 times). FIG. 5 is an electron micrograph of a complex of calcium carbonate fine particles synthesized in Experiment 1 and a fiber (cellulose nanofiber: CNF) (magnification: left 10000 times, right 50,000 times). FIG. 6 is an electron micrograph of a complex of calcium carbonate fine particles synthesized in Experiment 1 and fibers (TMP) (magnification: 2000 times). FIG. 7 is an electron micrograph (magnification: 2000 times) of the complex of calcium carbonate fine particles synthesized in Experiment 1 and fibers (CV-treated hemp pulp). FIG. 8 is a photograph of Experiment 2-1 (sample C0) (magnification: 2000 times from the left). FIG. 9 is a photograph of Experiment 2-2 (sample C1) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 109 is a photograph of Experiment 2-3 (Sample C2) (magnification: 50000 times). FIG. 11 is a photograph of Experiment 2-4 (sample C3) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 12 is a photograph of Experiment 2-5 (sample C4) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 13 is a photograph of Experiment 2-6 (sample C5) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 14 is a photograph of Experiment 3-1 (sample C6) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 15 is a photograph of Experiment 3-2 (sample C7) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 16 is a photograph of Experiment 3-3 (sample C8) (magnification: 2000 times, 10000 times, 50000 times from the left). FIG. 17 is a photograph of Experiment 3-4 (Sample C9) (magnification: 2000 ×, 50000 ×, from the left).

  In the present invention, a composite (fiber composite) of fine particles of silica or alumina and fibers is produced by synthesizing silica and / or alumina while spraying a liquid in a solution containing fibers.

Silica and / or Alumina According to the present invention, silica and / or alumina having a small average particle size can be complexed with fibers. Although the average primary particle diameter of the silica and / or alumina fine particles constituting the composite according to the present invention is less than 1 μm, the average primary particle diameter may be less than 500 nm, less than 200 nm, and even 100 nm or less. Also, the average primary particle size of the silica and / or alumina fine particles can be 10 nm or more.

  In addition, the silica and / or alumina obtained in the present invention may take the form of secondary particles in which fine primary particles are aggregated, and the secondary particles can be generated according to the application by the aging process. The agglomerates can also be reduced by grinding. As a method of grinding, ball mill, sand grinder mill, impact mill, high pressure homogenizer, low pressure homogenizer, Dyno mill, ultrasonic mill, kanda grinder, attritor, millstone type mill, vibration mill, cutter mill, jet mill, disintegrator, beating machine Short screw extruder, twin screw extruder, ultrasonic stirrer, household use juicer mixer and the like.

  The composite obtained by the present invention can be used in various forms, for example, powder, pellet, mold, aqueous suspension, paste, sheet, and other forms. In addition, the composite can be used as a main component and in the form of a molded article such as a mold or particles / pellets together with other materials. There is no particular limitation on the drier in the case of drying to form powder, for example, a flash drier, a band drier, a spray drier, etc. can be suitably used.

  According to the present invention, it is possible to obtain a composite of inorganic fine particles having a small primary particle diameter and a narrow particle size distribution and fibers, which is different from conventional calcium carbonate for paper making having a particle diameter of more than 1 μm. Can exhibit the following characteristics. Furthermore, unlike the case where inorganic fine particles having a small primary particle diameter are simply blended into the fibers, the composite of the present invention forms a complex with the fibers, so the inorganic fine particles are not only easily retained in the sheet but also aggregate. Thus, uniformly dispersed sheets can be obtained. It is clear from the result of electron microscope observation that the composite particles of the present invention are formed not only on the inside of the outer surface of the fiber and the inside of the lumen but also on the inside of the microfibrils.

  The average particle size, shape, etc. of the inorganic fine particles constituting the composite of the present invention can be confirmed by observation with an electron microscope. Furthermore, fine particles having various sizes and shapes can be complexed with fibers by adjusting the conditions at the time of synthesizing the inorganic fine particles.

  The complexes obtained by the present invention can be used in various applications. For example, but not limited to, paper, fiber, cellulose composite material, filter material, paint, plastic and other resins, rubber, elastomer, ceramic, glass, tire, building material (asphalt, asbestos, cement , Board, concrete, brick, tile, plywood, fiber board, etc., various carriers (catalyst carrier, pharmaceutical carrier, pesticide carrier, microorganism carrier, etc.), adsorbents (impurity removal, deodorization, dehumidification, etc.), anti-wrinkle agent, Clay, abrasives, modifiers, repair materials, heat insulation, moisture proofing materials, water repellents, water resistant materials, light shielding materials, sealants, shielding materials, insect repellents, adhesives, inks, cosmetics, medical materials, paste materials, etc. It can be widely used in any of Moreover, it can use for the various fillers in the said use, a coating agent, etc.

  Among them, the composite of the present invention is easy to apply to papermaking applications, for example, printing paper, newsprint, inkjet paper, PPC paper, kraft paper, wood free paper, coated paper, finely coated paper, wrapping paper, thin paper, color paper Paper, cast coated paper, non-carbon paper, label paper, thermal paper, various kinds of fancy paper, water-soluble paper, release paper, process paper, wallpaper base paper, incombustible paper, flame retardant paper, laminated base paper, battery separator, cushion paper , Tracing paper, impregnated paper, ODP paper, building material paper, cosmetic material paper, envelope paper, tape paper, heat exchange paper, synthetic fiber paper, sterile paper, water resistant paper, oil resistant paper, heat resistant paper, photocatalyst paper, cosmetic paper ( Fat-free paper etc., various sanitary papers (toilet paper, tissue paper, wipers, diapers, sanitary products etc.), tobacco paper, paperboard (liner, core base paper, white paperboard etc.), paper plate Paper, cup base paper, baking paper, abrasive paper, and synthetic paper.

  Moreover, when using the calcium carbonate composite obtained by this invention, the particle generally called an inorganic filler and an organic filler and various fibers can be used together. 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, delami kaolin) ), Talc, zinc oxide, zinc stearate, titanium dioxide, silica manufactured from sodium silicate and mineral acid (white carbon, silica / calcium carbonate composite, silica / titanium dioxide composite), white earth, bentonite, diatomaceous earth, Examples include calcium sulfate, zeolite, an inorganic filler that regenerates and utilizes ash obtained from the deinking step, and an inorganic filler that forms a complex with silica or calcium carbonate in the process of regeneration. As the calcium carbonate-silica composite, in addition to calcium carbonate and / or light calcium carbonate-silica composite, amorphous silica such as white carbon may be used in combination. As the organic filler, urea-formalin resin, polystyrene resin, phenol resin, micro hollow particle, acrylamide complex, substance derived from wood (fine fiber, micro fibril fiber, powder kenaf), modified insolubilized starch, non-gelatinized starch, etc. Can be mentioned. As the fibers, not only natural fibers such as cellulose but also synthetic fibers artificially synthesized from raw materials such as petroleum, furthermore, regenerated fibers (semi-synthetic fibers) such as rayon and lyocell, and further inorganic fibers etc. are not limited. It can be used. As natural fibers, in addition to the above, protein fibers such as wool, silk yarn and collagen fibers, and complex sugar chain fibers such as chitin / chitosan fibers and alginic acid fibers may be mentioned. Examples of cellulose-based materials include pulp fibers (wood pulp and non-wood pulp) and bacterial cellulose. Wood pulp may be produced by pulping wood materials. Examples of wood raw materials include red pine, black pine, todo pine, Japanese spruce, larch, fir, tsuga, tsuga, cypress, cypress, larch, silabe, spruce, hives, Douglas fir, hemlock, white fur, spruce, balsam fur, cedar, pine, Coniferous trees such as Melxi pine, Radiata pine, etc., and mixed materials thereof, hardwoods such as beech, hippopotamus, alder, larch, tub, shii, birch, poplar, taro, eucalyptus, mangrove, rawan, acacia and mixtures thereof The material is illustrated. The method for pulping the wood material is not particularly limited, and the pulping method generally used in the paper industry is exemplified. Wood pulp can be classified by the pulping method, for example, chemical pulp digested by the Kraft method, sulfite method, soda method, polysulfide method, etc .; mechanical pulp obtained by pulping by mechanical power such as refiner, grinder, etc .; Semi-chemical pulp obtained by mechanical pulping after pre-treatment by the following method; waste paper pulp; deinked pulp and the like. The wood pulp may be in the unbleached (before bleaching) state or in the bleached (after bleaching) state. Examples of non-wood-derived pulps include cotton, hemp, sisal, manila hemp, flax, persimmon, bamboo, bagasse, kenaf and the like. Wood pulp and non-wood pulp may be either unrefined or refined. Examples of synthetic fibers include polyesters, polyamides, polyolefins, acrylic fibers, and half fibers include rayon and acetate. Examples of inorganic fibers include glass fibers, carbon fibers, and various metal fibers. About these, you may use these individually or in combination of 2 or more types.

Liquid Spray In the preparation of the composite according to the present invention, silica and / or alumina are synthesized in the presence of fibers while the liquid is sprayed.

  In the present invention, cavitation may be generated by injecting a liquid. In the present invention, cavitation is a physical phenomenon in which generation and disappearance of bubbles occur in a short time due to a pressure difference in a fluid flow, and is also referred to as cavitation. Bubbles generated by cavitation (cavitation bubbles) are generated as nuclei of very small "bubble nuclei" of 100 microns or less present in the liquid when the pressure in the fluid falls below the saturation 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, generating cavitation bubbles by injecting fluid at high pressure, generating cavitation by stirring at high speed in fluid, generating cavitation by causing explosion in fluid, ultrasonic vibration It is conceivable that cavitation may be generated by a child (vibratory, cavitation).

  In the present invention, in particular, it is preferable to generate cavitation bubbles by injecting a fluid at high pressure, since generation and control of cavitation bubbles are easy. In this aspect, cavitation bubbles are generated simultaneously with expansion of the liquid itself due to extremely high shear force and rapid pressure reduction in the vicinity of the nozzle by compressing the jetted liquid using a pump etc. and injecting it at high speed via the nozzle etc. . The fluid jet method has a high generation efficiency of cavitation bubbles and can generate cavitation bubbles having a stronger colliding impact force. In the present invention, a controlled cavitation bubble is present in the synthesis of calcium carbonate, which is clearly different from a cavitation bubble which causes an uncontrollable harm that occurs naturally in fluid machinery.

  In the present invention, a reaction solution such as a raw material can be jetted as it is as a jet liquid, or any fluid can be jetted into the reaction vessel. The fluid from which the liquid jet forms a jet may be any of a liquid, a gas, a solid such as powder or pulp as long as it is in a fluid state, and may be a mixture thereof. Furthermore, if necessary, another fluid such as carbon dioxide gas can be added as a new fluid to the above fluid. The fluid and the new fluid may be uniformly mixed and jetted, but may be jetted separately.

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

Flow rate and pressure are particularly important because cavitation occurs when a 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, cavitation number (Cavitation Number) σ is defined as the following Equation 1 (Kato Yoji ed., “New version cavitation · foundation and recent progress”, Tsubaki Shoten 1999).

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

  The cavitation condition in the present invention is preferably such that the cavitation number σ described above is 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 preferred. If the cavitation number σ is less than 0.001, the pressure difference with the surroundings when the cavitation bubbles collapse is low, and the effect is small. If the cavitation number is larger than 0.5, the flow pressure difference is low and cavitation It becomes difficult to occur.

  When cavitation is generated by injecting the jetted liquid through the nozzle or orifice pipe, the pressure (upstream pressure) of the jetted liquid is more preferably 2 MPa or more and 15 MPa or less. If the upstream pressure is less than 0.01 MPa, a pressure difference is unlikely to occur between the upstream pressure and the downstream pressure, and the effect is small. Moreover, when it is higher than 30 MPa, a special pump and pressure vessel are required, and the energy consumption is large, which is disadvantageous in cost. On the other hand, the pressure in 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.

  The jet velocity of the jet liquid is desirably in the range of 1 m / sec to 200 m / sec, and preferably in the range of 20 m / sec to 100 m / sec. If the jet velocity is less than 1 m / sec, the effect is weak because the pressure drop is low and cavitation is less likely to occur. On the other hand, if it is more than 200 m / sec, it requires high pressure and requires a special device, which is disadvantageous in cost.

  The cavitation generation site in the present invention may be generated in a reaction vessel that synthesizes fine particles. Moreover, although it is also possible to process by one pass, it is also possible to circulate as many times as necessary. Furthermore, multiple generators can be used to process in parallel or in permutation.

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

  In the present invention, the pH of the reaction solution is basic at the start of the reaction when an alkali silicate is used as a starting material, and is acidic when an inorganic acid or an aluminum salt is used as a starting material. It changes to neutral as it progresses. 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 can be increased, and the pressure can be reduced accordingly, and stronger cavitation can be generated. Further, by pressurizing the pressure in the reaction vessel, the pressure in the region where the cavitation bubbles collapse is increased, and the pressure difference between the bubbles and the surroundings is increased, so that the bubbles are violently collapsed and the impact force can be increased. Further, in the case of introducing a gas such as carbon dioxide gas, dissolution and dispersion of the gas can be promoted. The reaction temperature is preferably 0 ° C. or more and 90 ° C. or less, and particularly preferably 10 ° C. or more and 60 ° C. or less. Generally, in the case of an aqueous solution, around 50 ° C. is preferable because the impact force is considered to be the maximum at the midpoint between the melting point and the boiling point, but even at temperatures below that, it is affected by the vapor pressure. If the above range is used, high effects can be obtained.

  In the present invention, the energy required to generate cavitation can be reduced by adding a surfactant. As surfactants to be used, known or novel surfactants, for example, nonionic surfactants such as fatty acid salts, higher alkyl sulfates, alkyl benzene sulfonates, higher alcohols, alkyl phenols, alkylene oxide adducts such as fatty acids, etc. And anionic surfactants, cationic surfactants, amphoteric surfactants and the like. It may be a single component or a mixture of two or more components. The addition amount may be an amount necessary to reduce the surface tension of the jetted liquid and / or the jetted liquid.

Reaction Conditions In the present invention, alumina and / or silica may be synthesized in the presence of fibers while spraying a liquid. When any one or more of an inorganic acid or an aluminum salt is used as a starting material for the reaction, the synthesis is performed by adding an alkali silicate. It can be synthesized by using an alkali metal silicate as a starting material and adding any one or more of an inorganic acid or an aluminum salt, but the formation using an inorganic acid and / or an aluminum salt as a starting material is more preferable. Fixation of matter to fibers is good. The inorganic acid is not particularly limited, and, for example, sulfuric acid, hydrochloric acid, nitric acid and the like can be used. Among these, sulfuric acid is particularly preferable in terms of cost and handling. As the aluminum salt, a sulfuric acid band, aluminum chloride, polyaluminum chloride, alum, potassium alum etc. may be mentioned. Among these, a sulfuric acid band can be suitably used. Examples of alkali silicates include sodium silicate and potassium silicate, but sodium silicate is preferable because it is easily available. The molar ratio of silicic acid and alkali may be any, but in general, those which are distributed as No. 3 silicic acid have a molar ratio of about SiO ₂ : Na ₂ O = 3 to 3.4: 1, which is preferable. It can be used. In the present invention, water is used for preparation of a suspension etc. As this water, ordinary tap water, industrial water, ground water, well water etc. can be used, ion-exchanged water, distilled water, etc. Ultrapure water, industrial wastewater, and water obtained in the carbonation step can be suitably used.

  In the present invention, the reaction solution can be circulated and used. By circulating the reaction solution in this manner, it is easy to increase the reaction efficiency and efficiently obtain the complex.

When producing the composite of the present invention, various known auxiliary agents can be added. For example, a chelating agent can be added to the carbonation reaction, and specifically, polyhydroxycarboxylic acids such as citric acid, malic acid and tartaric acid, dicarboxylic acids such as oxalic acid, sugar acids such as gluconic acid, iminodi Acetic acid, aminopolycarboxylic acids such as ethylenediaminetetraacetic acid and alkali metal salts thereof, alkali metal salts of polyphosphoric acid such as hexametaphosphoric acid and tripolyphosphoric acid, amino acids such as glutamic acid and aspartic acid and alkali metal salts thereof, acetylacetone, acetoacetic acid Examples thereof include methyl, ketones such as allyl acetoacetate, sugars such as sucrose, and polyols such as sorbitol. In addition, as surface treatment agents, saturated fatty acids such as palmitic acid and stearic acid, unsaturated fatty acids such as oleic acid and linoleic acid, resin acids such as alicyclic carboxylic acid and abietic acid, salts, esters, ethers and alcohols thereof Activators, sorbitan fatty acid esters, amide-based or amine-based surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonylphenyl ether, alpha-olefin sulfonate sodium, long-chain alkyl amino acids, amine oxides, alkyl amines, fourth Grade ammonium salts, amino carboxylic acids, phosphonic acids, polyvalent carboxylic acids, condensed phosphoric acids and the like can be added. Moreover, a dispersing agent can also be used as needed. Examples of the dispersant include sodium polyacrylate, sucrose fatty acid ester, glycerin fatty acid ester, acrylic acid-maleic acid copolymer ammonium salt, methacrylic acid-naphthoxy polyethylene glycol acrylate copolymer, 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. Also, the timing of addition is not particularly limited, and such an additive may be added in an amount of preferably 0.001 to 20%, more preferably 0.1 to 10%.

  The reaction conditions in the present invention are not particularly limited, and can be appropriately set according to the application. For example, the temperature of the reaction can be 10 to 100 ° C., preferably 20 to 90 ° C. The reaction temperature can control the temperature of the reaction solution by a temperature control device. If the temperature is low, the reaction efficiency decreases and the cost increases, but if it exceeds 90 ° C., coarse particles tend to be large.

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

  Furthermore, the reaction can be controlled by monitoring the pH of the reaction suspension, depending on the pH profile of the reaction solution, eg around pH 4-11, preferably pH 5-10, more preferably pH 6-9. The reaction can be performed until it reaches.

  Furthermore, the reaction can be controlled by the reaction time, and specifically, it can be controlled by adjusting the retention time of the reactant in the reaction vessel. In addition, in the present invention, the reaction can also be controlled by stirring the reaction solution in the reaction vessel or by using a multistage reaction.

  In the present invention, since a complex which is a reaction product is obtained as a suspension, storage in a storage tank or processing such as concentration, dehydration, pulverization, classification, ripening, dispersion, etc. is performed as necessary. Can. These may be known processes, and may be appropriately determined in consideration of applications, energy efficiency and the like. For example, concentration and dehydration processing is performed using a centrifugal dehydrator, a sedimentation concentrator, or the like. Examples of this centrifugal dehydrator include a decanter and a screw decanter. There is no particular limitation on the type of filter and dehydrator, and general ones can be used. For example, pressure dehydrator such as filter press, drum filter, belt press, tube press, etc. A calcium carbonate cake can be obtained by suitably using a vacuum drum dehydrator such as an oliver filter. As a method of grinding, ball mill, sand grinder mill, impact mill, high pressure homogenizer, low pressure homogenizer, Dyno mill, ultrasonic mill, kanda grinder, attritor, millstone type mill, vibration mill, cutter mill, jet mill, disintegrator, beating machine Short screw extruder, twin screw extruder, ultrasonic stirrer, household use juicer mixer and the like. Examples of classification methods include sieves such as mesh, slits or round holes of outward type or inward type, vibrating screens, heavy foreign matter cleaners, lightweight foreign matter cleaners, reverse cleaners, sieving testers and the like. As a method of dispersion, a high speed disperser, a low speed kneader, etc. may be mentioned.

  The composite obtained by the present invention can be incorporated into fillers and pigments in the form of a suspension without being completely dehydrated, but can also be dried to form a powder. The dryer in this case is also not particularly limited, but, for example, a flash dryer, a band dryer, a spray dryer and the like can be suitably used.

  The complexes obtained according to the invention can be modified by known methods. For example, in one embodiment, it is possible to hydrophobize the surface to enhance the miscibility with a resin or the like.

Fiber In the present invention, inorganic fine particles and fibers are complexed. The fibers constituting the composite are not particularly limited, but, for example, natural fibers such as cellulose, synthetic fibers artificially synthesized from raw materials such as petroleum, semisynthetic fibers such as rayon, and inorganic fibers are also possible. Etc. can be used without restriction. As natural fibers, in addition to the above, protein fibers such as wool, silk yarn and collagen fibers, and complex sugar chain fibers such as chitin / chitosan fibers and alginic acid fibers may be mentioned. Examples of cellulose-based materials include pulp fibers (wood pulp and non-wood pulp) and bacterial cellulose. Wood pulp may be produced by pulping wood materials. Examples of wood raw materials include red pine, black pine, todo pine, Japanese spruce, larch, fir, tsuga, tsuga, cypress, cypress, larch, silabe, spruce, hives, Douglas fir, hemlock, white fur, spruce, balsam fur, cedar, pine, Coniferous trees such as Melxi pine, Radiata pine, etc., and mixed materials thereof, hardwoods such as beech, hippopotamus, alder, larch, tub, shii, birch, poplar, taro, eucalyptus, mangrove, rawan, acacia and mixtures thereof The material is illustrated.

  The method for pulping the wood material is not particularly limited, and the pulping method generally used in the paper industry is exemplified. Wood pulp can be classified by the pulping method, for example, chemical pulp digested by the Kraft method, sulfite method, soda method, polysulfide method, etc .; mechanical pulp obtained by pulping by mechanical power such as refiner, grinder, etc .; Semi-chemical pulp obtained by mechanical pulping after pre-treatment by the following method; waste paper pulp; deinked pulp and the like. The wood pulp may be in the unbleached (before bleaching) state or in the bleached (after bleaching) state.

  Examples of non-wood-derived pulps include cotton, hemp, sisal, manila hemp, flax, persimmon, bamboo, bagasse, kenaf and the like.

  Pulp fibers may be either unbeaten or beaten, and may be selected according to the physical properties of the composite sheet, but it is preferable to beat. As a result, improvement in sheet strength and promotion of calcium carbonate fixation can be expected.

  Examples of synthetic fibers include polyesters, polyamides, polyolefins, acrylic fibers, and half fibers include rayon and acetate. Examples of inorganic fibers include glass fibers, carbon fibers, and various metal fibers.

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

In a preferred embodiment, the fibers comprising the composite of the present invention are pulp fibers. Also, for example, fibrous material recovered from paper mill effluent 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 can be synthesized also in shape.

  In the present invention, in addition to fibers, materials which are not directly involved in the formation of inorganic particles but can be incorporated into inorganic particles to form composite particles can be used. In the present invention, although fibers such as pulp fibers are used, these substances can be further incorporated by synthesizing silica or alumina in a solution containing inorganic particles, organic particles, polymers and the like. It is possible to produce composite particles.

Silica and / or Alumina In the present invention, fine particles of silica and / or alumina are synthesized while spraying a liquid in a solution containing fibers, but the synthesis method can be according to a known method. Further, in the present invention, not only fine particles of silica or alumina but other inorganic particles can be complexed with fibers.

  In a preferred embodiment, in the present invention, fine particles of calcium carbonate as well as silica and alumina can be complexed with fibers. In this case, although the average primary particle diameter of the calcium carbonate fine particles constituting the complex is less than 1 μm, calcium carbonate having an average primary particle diameter of less than 500 nm, calcium carbonate having an average primary particle diameter of less than 200 nm, and further 100 nm or less Calcium carbonate can be used. Further, the average primary particle diameter of the calcium carbonate fine particles can be 10 nm or more.

  In addition, the calcium carbonate obtained in the present invention may take the form of secondary particles in which fine primary particles are aggregated, so that secondary particles according to the application can be formed by the aging step, and aggregation is caused by pulverization. It is also possible to crush the mass. As a method of grinding, ball mill, sand grinder mill, impact mill, high pressure homogenizer, low pressure homogenizer, Dyno mill, ultrasonic mill, kanda grinder, attritor, millstone type mill, vibration mill, cutter mill, jet mill, disintegrator, beating machine Short screw extruder, twin screw extruder, ultrasonic stirrer, household use juicer mixer and the like.

  The average particle size, shape, etc. of calcium carbonate constituting the complex of the present invention can be confirmed by observation with an electron microscope. Furthermore, calcium carbonate fine particles having various sizes and shapes can be complexed with fibers by adjusting the conditions for synthesizing calcium carbonate.

  The synthesis method of calcium carbonate is not particularly limited, but calcium carbonate can be synthesized by, for example, carbon dioxide method, soluble salt reaction method, lime-soda method, soda method, etc. In a preferred embodiment, calcium carbonate is synthesized by carbon dioxide method Synthesize

In general, when calcium carbonate is produced by the carbon dioxide method, lime (lime) is used as a calcium source, and a quenching process to obtain slaked lime Ca (OH) ₂ by adding water to quick lime CaO, and carbon dioxide CO _{2 to} slaked lime calcium carbonate is synthesized by the carbonation step to obtain a calcium carbonate CaCO ₃ is blown. At this time, a suspension of slaked lime prepared by adding water to quicklime may be passed through a screen to remove low-soluble lime granules contained in the suspension. Slaked lime may be used directly as a calcium source. When calcium carbonate is synthesized by the carbon dioxide method in the present invention, the carbonation reaction may be performed in the presence of a cavitation bubble.

Generally, as a reaction vessel (carbonation reactor: carbonator) for producing calcium carbonate by a carbon dioxide method, a gas-blowing type carbonator and a mechanical stirring type carbonator are known. In a gas-blowing type carbonator, carbon dioxide gas is blown into a carbonation reaction tank containing slaked lime suspension (lime milk) to react slaked lime with carbon dioxide gas. However, the bubble size can be obtained simply by bubbling carbon dioxide gas. It is difficult to control them uniformly and finely, and there are limitations in terms of reaction efficiency. On the other hand, in a mechanically stirred type carbonator, a stirrer is provided inside the carbonator, and carbon dioxide gas is introduced near the stirrer to make the carbon dioxide gas into fine bubbles and improve the reaction efficiency of slaked lime and carbon dioxide gas. ("Cement, gypsum, and lime handbook", Tech. Hall, 1995, p. 495).

  However, when stirring is performed with a stirrer provided inside the carbonation reaction tank like a mechanical stirring type carbonator, if the concentration of the reaction liquid is high or the carbonation reaction proceeds, the resistance of the reaction liquid is large and sufficient stirring is difficult As a result, it may be difficult to control the carbonation reaction properly, or a considerable load may be applied to the stirrer to perform sufficient stirring, which may be disadvantageous in terms of energy. Also, a gas inlet is at the bottom of the carbonator, and a stirrer blade is located near the bottom of the carbonator for better stirring. Lime screen residue, which has low solubility, settles constantly and always stays at the bottom, blocking the gas inlet and disturbing the balance of the stirrer. Furthermore, in the conventional method, in addition to the carbonator, a stirrer and equipment for introducing carbon dioxide gas to the carbonator are required, and the equipment cost also increases. And in the mechanical agitation type carbonator, although the reaction efficiency of slaked lime and carbon dioxide gas is improved by finely dividing the carbon dioxide gas supplied near the stirrer by the stirrer, carbon dioxide gas is sufficiently when the concentration of the reaction liquid is high. In some cases, it has been difficult to accurately control the form and the like of calcium carbonate produced even in the carbonation reaction. In the present invention, by synthesizing calcium carbonate in the presence of cavitation bubbles, it is possible to efficiently advance the carbonation reaction to produce uniform calcium carbonate fine particles. In particular, by using jet cavitation, sufficient stirring can be performed without mechanical stirrers such as blades. In the present invention, conventionally known reaction vessels can be used, and of course, the above-mentioned gas-blowing carbonator and mechanical agitation type carbonator can be used without any problem, and these vessels can be used as nozzles or the like. You may combine jet cavitation using.

  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, and still more preferably 1 to 20. It is about% by weight. When the solid concentration is low, the reaction efficiency is low, the production cost is high, and when the solid concentration is too high, the flowability is poor and the reaction efficiency is lowered. In the present invention, since calcium carbonate is synthesized in the presence of cavitation bubbles, the reaction liquid and carbon dioxide gas can be suitably mixed even using a suspension (slurry) having a high solid concentration.

  As an aqueous suspension containing slaked lime, those generally used for calcium carbonate synthesis can be used, for example, it is prepared by mixing slaked lime with water, or digesting quick lime (calcium oxide) with water It can be prepared. The conditions for the dissolution are not particularly limited. For example, the concentration of CaO can be 0.1 wt% or more, preferably 1 wt% or more, and the temperature can be 20 to 100 ° C., preferably 30 to 100 ° C. . Also, the average residence time in the slaking reaction tank (slager) is not particularly limited, but may be, for example, 5 minutes to 5 hours, preferably 2 hours or less. It will be appreciated that the slaker may be batch or continuous. In the present invention, the carbonation reaction tank (carbonator) and the deinking reaction tank (slacker) may be separated, or one reaction tank may be used as the carbonation reaction tank and the deinking reaction tank. Good.

  In the present invention, a gas containing carbon dioxide (carbon dioxide gas) is blown into the reaction vessel and mixed with the reaction liquid. 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 furthermore, the carbonation gas can be finely divided by cavitation bubbles, thereby efficiently performing the carbonation reaction. Can.

  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. For example, it is preferable to use carbon dioxide gas having a flow rate of 100 to 10000 L / hour per 1 kg of slaked lime.

  The gas containing carbon dioxide of the present invention may be substantially pure carbon dioxide gas, or may be 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 a 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, a coal boiler, a heavy oil boiler or the like of a paper mill can be suitably used as a carbon dioxide containing gas. Besides, it is also possible to carry out the carbonation reaction using carbon dioxide generated from the lime calcining step.

Using the complex according to the molding invention conjugates, as appropriate, it is also possible to produce a molded product (the body). For example, when the composite obtained by the present invention is sheeted, a sheet with high ash content can be easily obtained. As a paper machine (paper making machine) used for sheet production, there are mentioned, for example, a Fourdrinier paper machine, a circular mesh paper machine, a gap former, a hybrid former, a multilayer paper machine, a known paper making machine combining these paper making methods. Be The press linear pressure in the paper machine and the calender linear pressure in the case of performing the calendering in the latter stage can be determined within a range that does not affect the operability and the performance of the composite sheet. In addition, starch, various polymers, pigments and mixtures thereof may be applied to the formed sheet by impregnation or application.

  Wet and / or dry strength agents (paper strength agents) can be added during sheeting. 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, polyethylene imine, glyoxal, gum, mannogalactan polyethylene imine, polyacrylamide resin, polyvinyl amine And resins such as polyvinyl alcohol; composite polymers or copolymers consisting of two or more selected from the above resins; starch and modified starch; carboxymethyl cellulose, guar gum, urea resin and the like. The addition amount of the paper strength agent is not particularly limited.

Moreover, in order to promote the fixation of the filler to the fiber, and to improve the yield of the filler and the fiber, a polymer or inorganic substance can also be added. For example, polyethyleneimine and modified polyethyleneimine containing tertiary and / or quaternary ammonium groups as a coagulant, polyalkyleneimine, dicyandiamide polymer, polyamine, polyamine / epichlorohydrin polymer, and dialkyldiaryl quaternary ammonium monomer, dialkyl Polymers such as aminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide and dialkylaminoalkyl methacrylamide and acrylamide polymer, polymer consisting of monoamines and epihalohydrin, polymer having polyvinylamine and vinylamine moiety and mixtures thereof In addition to the hydrophobic polymer, a copolymer obtained by copolymerizing an anionic group such as a carboxyl group or a sulfone group in the molecule of the polymer. Onritchi of zwitterionic polymer, and a mixture of cationic polymer and an anionic or zwitterionic polymers may be used. Further, as the retention agent, cationic or anionic, amphoteric polyacrylamide based material can be used. In addition to these, it is also possible to apply a retention system called a so-called dual polymer in which at least one or more cationic or anionic polymers are used in combination, and at least one or more anionic bentonite, colloidal silica, polysilicic acid, A multicomponent retention system comprising one or more inorganic fine particles such as polysilicic acid or polysilicate microgel and their modified products of aluminum, and organic fine particles having a particle diameter of 100 μm or less, which are so-called micropolymers obtained by crosslinking polymerization of acrylamide. It is also good. In particular, when the polyacrylamide based material used alone or in combination has a weight average molecular weight of 2,000,000 Dalton or more according to the intrinsic viscosity method, good retention can be obtained, preferably 5,000,000 Dalton or more, more preferably In the case of the above-mentioned acrylamide-based material having a molecular weight of not less than 10,000,000 Daltons and less than 30,000,000 Daltons, a very high yield can be obtained. The form of the polyacrylamide based material may be an emulsion type or a solution type. The specific composition is not particularly limited as long as it contains an acrylamide monomer unit as a structural unit in the substance, but, for example, a copolymer of a quaternary ammonium salt of acrylic acid ester and acrylamide, or acrylamide And quaternized ammonium salt after copolymerization with acrylic acid ester. The cationic charge density of the cationic polyacrylamide based material is not particularly limited.

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

  It is also possible to use a forming method other than sheeting, for example, a method of pouring a raw material into a mold so as to be called a pulp mold, suction dehydration, drying, spreading on the surface of molded articles such as resin and metal, and drying. Thereafter, moldings having various shapes can be obtained by a method of peeling from a substrate or the like. Alternatively, the resin may be mixed and molded into a plastic-like shape, or may be molded into a ceramic-like shape by adding a mineral such as silica or alumina and firing. In the combination, drying, and molding described above, only one type of composite can be used, or two or more types of composites can be mixed and used. When two or more types of composites are used, those obtained by mixing them in advance may be used, or those obtained by blending, drying and forming each may be mixed later.

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

  The present invention will be more specifically described below with reference to experimental examples, but the present invention is not limited to such experimental examples. Further, unless otherwise specified in the present specification, concentrations, parts, etc. are on a weight basis, and a numerical range is described as including its end points.

Experiment 1 (reference example): Synthesis of calcium carbonate fine particle / fiber composite < synthesis of calcium carbonate / fiber composite>
An aqueous suspension containing calcium hydroxide (slaked lime: Ca (OH) ₂ , Wako Pure Chemical Industries, 2% by weight) and fibers (0.5%) was prepared. 9.5 L of this aqueous suspension was placed in a 45 L cavitation apparatus, carbon dioxide gas was blown into the reaction vessel, and a complex of calcium carbonate fine particles and fibers was synthesized by the carbon dioxide method. The reaction temperature was about 25 ° C., carbon dioxide gas was supplied from a commercial liquefied gas, the amount of carbon dioxide gas blown was 12 L / min, and the reaction was stopped when the pH of the reaction solution reached about 7 (before the reaction) PH of about 12.8).

  In the synthesis of the complex, cavitation bubbles were generated in the reaction vessel by circulating the reaction solution and injecting it into the reaction vessel as shown in FIG. Specifically, the reaction solution was jetted at high pressure through a nozzle (nozzle diameter: 1.5 mm) to generate cavitation bubbles, but the jet velocity was about 70 m / s, and the inlet pressure (upstream pressure) was The outlet pressure (downstream pressure) was 7 MPa and 0.3 MPa.

In this experiment, the following four types were used as fibers to form a complex with calcium carbonate fine particles. Details of each fiber are shown below.
(1) Hardwood pulp fiber microfibrillated on the surface (CV treated pulp)
(2) Cellulose nanofibers (TEMPO oxidized pulp)
(3) Thermo mechanical pulp (TMP)
(4) Hemp pulp fiber microfibrillated on the surface (Hardwood pulp fiber microfibrillated on the surface) Pulp suspension (concentration: 0.5% was prepared. The pulp suspension was placed in a reaction vessel and cavitation bubbles were generated by introducing a jet into the reaction vessel. The reaction solution was injected at high pressure through a nozzle (nozzle diameter: 1.5 mm) to generate cavitation bubbles. The jet velocity was about 70 m / s, the inlet pressure (upstream pressure) was 7 MPa, and the outlet pressure (downstream pressure) was 0.3 MPa. This cavitation treatment was performed for about 1 hour until the CSF of LBKP was less than 100 mL.

  An electron micrograph of the pulp thus obtained is shown in FIG. 2. The microfibrils on the surface of the fiber were exfoliated in layers, and the average fiber length measured with a fiber tester (Lorentzen & Wettre) was 0.69 mm. .

  (Cellulose Nanofiber) NBKP oxidized by N-oxyl compound was beaten with a Nyagalabiter for about 15 minutes until the CSF was less than 100 mL, to obtain a cellulose nanofiber. The average fiber length of the obtained fiber was 0.84 mm (an electron micrograph is shown in FIG. 3).

(Thermomechanical pulp) Thermomechanical pulp (TMP) in which CSF has been refined to about 400 mL
(Hemp pulp with microfibrillated surface) In the same manner as the above-mentioned hardwood pulp fiber, hemp pulp was subjected to CV treatment until the CSF was lower than 100 mL to obtain hemp pulp with microfibrillated surface.

<Evaluation of complex>
The electron micrograph of the obtained complex is shown to FIGS. FIG. 4 is an electron micrograph of a composite of cavitation-treated hardwood pulp fibers and calcium carbonate fine particles. As apparent from FIG. 4, in this composite, many calcium carbonate fine particles were precipitated on the fiber surface, and the primary particle diameter of calcium carbonate was about 40 to 100 nm (average: about 80 nm). In particular, many calcium carbonate fine particles were formed in the fibril part of the pulp fiber.

  FIG. 5 is an electron micrograph of a complex of TEMPO oxidized pulp and calcium carbonate fine particles. As is clear from FIG. 5, even in this composite, many calcium carbonate fine particles were precipitated on the fiber surface, and the primary particle diameter of the calcium carbonate fine particles was about 40 to 100 nm (average: about 80 nm). Also in this complex, many calcium carbonate fine particles were formed in the fibril part of the pulp fiber.

  Moreover, when TMP was used (FIG. 6) and hemp pulp was used (FIG. 7), it was observed that calcium carbonate having a primary particle diameter of 40 to 80 nm covered the fiber surface and was self-fixed. .

  The reaction solution containing the complex was suction filtered with filter paper and observed. The complex of the fiber and the calcium carbonate fine particle was present stably, and the calcium carbonate fine particle did not fall off from the fiber.

  Moreover, when the ash content of these composites was measured, it was 81 to 82 weight% of a composite, and it corresponded with the theoretical value 82 weight% calculated from the preparation ratio of the raw material (pulp / calcium hydroxide). Here, the ash content of the complex was calculated from the ratio of the weight of the remaining ash to the original solid content after heating the complex at 525 ° C. for about 2 hours (JIS P 8251: 2003).

Experiment 2 (Reference Example): Synthesis of Complex of Calcium Carbonate Microparticles and Fiber A complex was synthesized under various conditions, and an electron micrograph was taken.
(Experiment 2-1: Sample C0, FIG. 8)
A composite was synthesized in the same manner as in Experiment 1 except that hardwood bleached kraft pulp (LBKP, CSF: 460 mL, without cavitation treatment) was used as the fiber. As a result of observation by an electron microscope, calcium carbonate having a primary particle size of 40 to 100 nm was self-fixed on the fiber surface. The ash content of the complex was 83%, which was almost the same as the theoretical value (84%) calculated from the preparation amount.
(Experiment 2-2: Sample C1, FIG. 9)
The fibers were synthesized in the same manner as in Experiment 1 except that 1250 g of LBKP (CSF: 460 mL, without cavitation treatment) and 1250 g of calcium hydroxide were used as fibers, and the total amount of the aqueous suspension of Ca (OH) ₂ was 100 L. . As a result of observation by an electron microscope, it was observed that calcium carbonate having a primary particle diameter of 60 to 90 nm covered the fiber surface and was self-fixed. As a result of measuring the ash content, it was 56%, which was almost equal to the theoretical value (58%).
(Experiment 2-3: Sample C2, FIG. 10)
Using 8300 g of LBKP / NBKP mixed pulp (weight ratio: 8/2, CSF: 50 ml, without cavitation), 8300 g of calcium hydroxide as fibers, total amount of aqueous suspension of Ca (OH) ₂ is 415 L, A complex was synthesized in the same manner as in Experiment 1 except that the carbon dioxide flow rate was 40 L / min and the reaction initiation temperature was 16 ° C.

As a result of observation by an electron microscope, it was observed that calcium carbonate having a primary particle diameter of 60 to 90 nm covered the fiber surface and was self-fixed. As a result of measuring the ash content, it was 56%, which was almost equal to the theoretical value (58%).
(Experiment 2-4: Sample C3, FIG. 11)
A complex was synthesized in the same manner as in Experiment 1 except that the preparation concentration of calcium hydroxide was 0.74% and the flow rate of carbon dioxide was 5 L / min.

As a result of observation by an electron microscope, it was observed that calcium carbonate having a primary particle diameter of 30 to 80 nm covered the fiber surface and was self-fixed. As a result of measuring an ash content, it was all 48% and almost equivalent to the theoretical value (50%).
(Experiment 2-5: Sample C4, FIG. 12)
The cavitation nozzle used was synthesized in the same manner as sample C3 except that the cavitation nozzle used was changed to two fluid correspondence (a calcium hydroxide suspension is mixed with carbon dioxide gas immediately before being discharged from the nozzle).

As a result of observation by an electron microscope, it was observed that calcium carbonate having a primary particle diameter of 30 to 80 nm covered the fiber surface and was self-fixed. As a result of measuring an ash content, it was all 48% and almost equivalent to the theoretical value (50%).
(Experiment 2-6: Sample C5, FIG. 13)
The raw material used was synthesized in the same manner as sample C4 except that quick lime was used. As a result of observation by an electron microscope, it was observed that calcium carbonate having a primary particle diameter of 40 to 80 nm covered the fiber surface and was self-fixed.

Experiment 3: Synthesis of Composite of Fine Particles of Silica and / or Alumina and Fiber A fiber composite was synthesized under the following conditions, and an electron micrograph was taken.
(Experiment 3-1: Sample C6, FIG. 14)
280 g of calcium hydroxide and 70 g of pulp (LBKP, CSF: about 460 mL) were mixed, and tap water was added to make it 14 L. After adding 400 g of sodium silicate (about 30% in SiO ₂ conversion), the mixture was charged into the reaction vessel. The subsequent procedure and reaction conditions were the same as in Experiment 1, but the reaction was stopped when the pH reached about 6.7.

As a result of electron microscopic observation, it was observed that particles having a primary particle diameter of about 20 to 50 nm, which is considered to be silica, were deposited on the surface of calcium carbonate. Moreover, when the abundance ratio of silica (silicon dioxide, SiO ₂ ) and calcium carbonate (CaCO ₃ ) was analyzed by fluorescent X-ray, it was confirmed that both silica and calcium carbonate were present (Table 2).
(Experiment 3-2: Sample C7, FIG. 15)
After the pH reached about 6.7 in Experiment 3-1, an aqueous solution of aluminum sulfate (0.8% in terms of alumina) was further added to react until the pH reached 6.2.

As a result of electron microscopic observation, it was observed that particles having a primary particle diameter of about 20 to 50 nm, which is considered to be silica, were deposited on the surface of calcium carbonate.
(Experiment 3-3: Sample C8, FIG. 16)
29 g of sodium silicate (about 30% in terms of SiO ₂ ) is added to 1 kg of the composite slurry of sample C0 (concentration: 2.9%) and stirred by a laboratory mixer, and 41 g of an aqueous sulfuric acid solution (10%) is added to form a composite Synthesized.

As a result of electron microscopic observation, it was confirmed that silica of similar size was present on fibers (LBKP) together with calcium carbonate of about 80 nm in primary particle shape. When the abundance ratio of silica (SiO ₂ ) and calcium carbonate (CaCO ₃ ) was analyzed by fluorescent X-ray, it was confirmed that both silica and calcium carbonate were present (Table 2).
(Experiment 3-4: Sample C9, FIG. 17)
60 g of pulp (LBKP / NBKP = 8/2, CSF: about 50 mL) and sulfuric acid band aqueous solution (0.8% alumina equivalent, 58 mL) were mixed, and tap water was added to make it 12 L. The subsequent procedure and reaction conditions are the same as in Experiment 1, but instead of blowing in carbon dioxide gas, 380 g of sodium silicate (about 30% in terms of SiO ₂ ) is dropped in the middle of the reaction to make the pH about 9.1. The reaction was stopped when it came to

  As a result of electron microscopic observation, it has been confirmed that alumina-silica composite crystals having a primary particle shape of 20 to 50 nm are precipitated on pulp fibers (LBKP).

Claims (3)

Fiber composite silica and / or alumina particles and calcium carbonate particles having an average primary particle diameter of 100nm or less is deposited on the surface of the cellulose textiles.   The fiber composite according to claim 1, wherein the fiber is a wood-derived cellulose fiber. The fiber composite according to claim 1, wherein the fiber is a pulp fiber.