WO2021045198A1

WO2021045198A1 - Composite fiber comprising cellulose fiber and inorganic particles, and manufacturing method for same

Info

Publication number: WO2021045198A1
Application number: PCT/JP2020/033627
Authority: WO
Inventors: 絢香長谷川; 萌渕瀬
Original assignee: 日本製紙株式会社
Priority date: 2019-09-06
Filing date: 2020-09-04
Publication date: 2021-03-11
Also published as: US20220290373A1; CN114144553A; JPWO2021045198A1; JP7123178B2; EP4026946A1; EP4026946A4; JP2022133416A

Abstract

The present invention addresses the problem of providing a composite fiber in which the surfaces of cellulose fibers are firmly covered with numerous inorganic particles.　In the present invention, (D50-D10)/D50 calculated from particle size distribution of (a) or (b) is used as an index, making it possible to produce an excellent composite fiber comprising cellulose fibers and inorganic particles. (a) A filtered liquid obtained by filtering an aqueous suspension liquid of the composite fiber with 0.1% solid content concentration through a 60 mesh sieve (aperture 250 μm); and (b) when an aqueous suspension liquid of the composite fiber with 0.3% solid content concentration is analyzed with a fiber classification analysis device, under a condition of a flow rate of 5.7 L/min, a water temperature of 25±1°C, and a total outflow of 22 L, a fraction corresponding to outflow (L) of 18.51 to 19.50, outflow time (sec) of 37.4 to 48.0.

Description

Composite fiber of cellulose fiber and inorganic particles and its manufacturing method

The present invention relates to a composite fiber of cellulose fiber and inorganic particles and a method for producing the same.

Fibers such as wood 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 so far, the fibers have been surface-modified. Technology is being developed.

For example, regarding a technique for precipitating inorganic particles on a fiber such as a cellulose fiber, Patent Document 1 describes a complex in which crystalline calcium carbonate is mechanically bonded onto 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.

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

In the conventional composite fiber in which the surface of the cellulose fiber is coated with inorganic particles, the binding strength between the cellulose fiber and the inorganic particle is not sufficient, the amount of the inorganic particle coated on the cellulose fiber is small, or the inorganic particle is formed from the cellulose fiber. Sometimes it dropped out. In view of such a situation, an object of the present invention is to provide a composite fiber in which the surface of the cellulose fiber is strongly coated with many inorganic particles.

The present invention is not limited to this, but includes the following inventions.
[1] A method for producing a composite fiber of cellulose fiber and inorganic particles.
The process of synthesizing inorganic particles in a solution containing cellulose fibers to obtain composite fibers,
The following (a) or (b):
(A) A filtrate obtained by filtering an aqueous suspension of composite fibers having a solid content concentration of 0.1% with a sieve of 60 mesh (opening 250 μm).
(B) An aqueous suspension of composite fibers having a solid content concentration of 0.3% was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total outflow of 22 L. Fractions corresponding to the outflow amount (L) 18.51 to 19.50 and the outflow time (sec) 37.4 to 48.0.
To calculate (D50-D10) / D50 by measuring the particle size distribution of
The above method, including.
[2] The method according to [1], wherein the aqueous suspension of the composite fiber is adjusted so that (D50-D10) / D50 is 0.85 or less.
[3] The method according to [1] or [2], wherein the average fiber diameter of the composite fiber is 500 nm or more.
[4] The method according to any one of [1] to [3], wherein the inorganic particles contain a metal salt of calcium, magnesium, barium or aluminum, metal particles containing titanium, copper or zinc, or a silicate. ..
[5] A method for producing a composite fiber sheet, which comprises a step of forming a sheet from the composite fibers obtained by any of the methods [1] to [4].
[6] A composite fiber of cellulose fibers and inorganic particles, which has the following (a) or (b):
(A) A filtrate obtained by filtering an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve having a solid content of 0.3% (b) of a composite fiber having a solid content concentration of 0.3%. When the aqueous suspension was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total runoff of 22 L, the runoff (L) 18.51-19. 50, Fraction corresponding to outflow time (sec) 37.4-48.0,
The composite fiber having a value of (D50-D10) / D50 calculated from the particle size distribution of 0.85 or less.
[7] A composite fiber of cellulose fibers and inorganic particles obtained by treating an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve of 60 mesh (opening 250 μm) and passing through the sieve. The composite fiber having a (D50-D10) / D50 value of 0.85 or less calculated from the particle size distribution of the filtrate that has passed through the sieve.
[8] An aqueous suspension of composite fibers having a solid content concentration of 0.3% was classified using a fiber classification analyzer under the conditions of a flow velocity of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total outflow of 22 L. , A composite fiber of cellulose fibers and inorganic particles obtained from a fraction corresponding to an outflow amount (L) of 18.51 to 19.50 and an outflow time (sec) of 37.4 to 48.0. The composite fiber having a value of (D50-D10) / D50 calculated from the particle size distribution of 0.85 or less.
[9] A method for analyzing a composite fiber of cellulose fibers and inorganic particles, wherein the following (a) or (b):
(A) A filtrate obtained by filtering an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve having a solid content of 0.3% (b) of a composite fiber having a solid content concentration of 0.3%. When the aqueous suspension was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total runoff of 22 L, the runoff (L) 18.51-19. 50, Fraction corresponding to outflow time (sec) 37.4-48.0,
The above method, which comprises the step of measuring the particle size distribution of (D50-D10) / D50 and calculating (D50-D10) / D50.

According to the present invention, it is possible to obtain a composite fiber in which the surface of the cellulose fiber is strongly coated with many inorganic particles and the production efficiency in a post-process such as dehydration or sheet formation can be improved.

Since the inorganic particles and the cellulose fibers are more strongly bound than the conventional composite fiber, the inorganic particles are less likely to fall off during dehydration or sheet formation (excellent in the yield of the inorganic particles in the subsequent process), and the particles are small. Since there are few free particles with a diameter, the drainage is also good. Improvement of dehydration and drainage leads to improvement of productivity (dehydration speed and speed of extraction) of various products, and also functional inorganic particles are hard to fall off. Therefore, the present invention uses composite fibers as a material. It also leads to improved functionality of products.

It is an electron micrograph of sample 1 (magnification: 3000 times). It is an electron micrograph of sample 2 (magnification: 3000 times). It is an electron micrograph of sample 3 (magnification: 3000 times). It is an electron micrograph of sample 4 (magnification: 3000 times). It is an electron micrograph of sample 5 (magnification: 3000 times). It is an electron micrograph of sample 6 (magnification: 3000 times). It is an electron micrograph of sample 7 (magnification: 3000 times). It is an electron micrograph of sample 8 (magnification: 3000 times). It is an electron micrograph of sample 9 (magnification: 3000 times). It is an electron micrograph of sample 10 (left: 3000 times, right: 10000 times). It is an electron micrograph of sample 11 (left: 3000 times, right: 10000 times). It is an electron micrograph of sample 12 (left: 3000 times, right: 10000 times). It is an electron micrograph of sample A (magnification: 3000 times). It is an electron micrograph of sample B (magnification: 3000 times). It is an electron micrograph of sample C1 (magnification: 3000 times). It is an electron micrograph of sample C2 (magnification: 3000 times). It is an electron micrograph of sample D1 (magnification: 3000 times). It is an electron micrograph of sample D2 (magnification: 3000 times).

The present invention relates to a composite fiber (composite) in which the surface of the cellulose fiber is strongly coated with inorganic particles. In a preferred embodiment, the composite fiber according to the present invention has 15% or more of the fiber surface coated with inorganic particles.

In the composite fiber according to the present invention, the fiber and the inorganic particle are not simply mixed, but the fiber and the inorganic particle are bound by a hydrogen bond or the like, so that the inorganic particle is less likely to fall off from the fiber. The strength of binding of fibers and inorganic particles in a complex can generally be evaluated by a numerical value such as ash yield (%, that is, sheet ash ÷ complex ash before dissociation × 100). .. Specifically, the complex is dispersed in water, adjusted to a solid content concentration of 0.2%, 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. However, in the present invention, by classifying the composite fiber, it is possible to evaluate a good composite fiber having a strong binding even if the strength of the binding cannot be sufficiently evaluated by the conventional method.

In the present invention, the composite particles of the cellulose fibers and the composite fibers of the inorganic particles can be appropriately evaluated by analyzing the particle size distribution of (a) or (b) below.
(A) A filtrate obtained by filtering an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve of 60 mesh (opening 250 μm) (b) An aqueous suspension of a composite fiber having a solid content concentration of 0.3%. When the turbid liquid was classified using a fiber classification analyzer under the conditions of a flow velocity of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total outflow amount of 22 L, the outflow amount (L) 18.51 to 19.50, Fraction corresponding to outflow time (sec) 37.4-48.0

Specifically, the numerical value of (D50-D10) / D50 calculated from the volume-based particle size distribution of (a) or (b) above can be used as an index. Here, D10 and D50 are particle diameters measured from a volume-based particle size distribution, D10 is a cumulative 10% particle diameter, and D50 is a cumulative 50% particle diameter. The smaller the value of (D50-D10) / D50, the narrower the particle size distribution of the sample, indicating that the inorganic substance is firmly fixed on the fiber surface. In a preferred embodiment, the value of (D50-D10) / D50 is 0.85 or less.

Synthesis of Composite Fibers In the present invention, composite fibers can be synthesized by synthesizing inorganic particles in a solution containing fibers such as cellulose fibers. This is because the fiber surface serves as a suitable field for the precipitation of inorganic particles, and it is easy to synthesize composite fibers. As a method for synthesizing the composite fiber, for example, a solution containing a precursor of the fiber and the inorganic particle may be stirred and mixed in an open reaction tank to synthesize the composite, or a precursor of the fiber and the inorganic particle may be synthesized. It may be synthesized by injecting an aqueous suspension containing the above into a reaction vessel. As will be described later, when an aqueous suspension of an inorganic precursor is injected into the reaction vessel, cavitation bubbles may be generated and inorganic particles may be synthesized in the presence of the cavitation bubbles. Each of the inorganic particles can be synthesized on the cellulose fiber by a known reaction.

In general, the formation of inorganic particles is captured when the size of inorganic particles exceeds the critical size after shifting from the cluster state (repeating aggregation and dispersal at the stage where the number of atoms and molecules gathered is small) to the nucleus (from the cluster to the stable assembly state). It is known that atoms and molecules do not disperse) and grow (new atoms and molecules gather in the nucleus and the particles become larger), and the higher the raw material concentration and reaction temperature, the more nucleation occurs. It is said to be easy. The composite fiber of the present invention is mainly produced on the fiber by adjusting the raw material concentration, the beating degree (specific surface area) of the pulp, the viscosity of the solution containing the fiber, the concentration and addition speed of the added chemicals, the reaction temperature, and the stirring speed. By efficiently binding nuclei and promoting particle growth, it is possible to obtain a composite fiber in which the surface of the cellulose fiber is strongly coated with inorganic particles.

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 fiber 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 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 is 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.

Cavitation occurs when the liquid is accelerated and the local pressure becomes lower than the vapor pressure of the liquid, so the flow velocity and pressure are especially important. From this, it is desirable that the basic dimensionless number representing the cavitation state, the cavitation number σ, is 0.001 or more and 0.5 or less, and 0.003 or more and 0.2 or less. It is preferable, and it is particularly preferable that it is 0.01 or more and 0.1 or less. 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, a pressure difference with the downstream pressure is unlikely to occur 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 that do not generate cavitation bubbles. 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 for generating cavitation may be performed in a container open to the atmosphere, but it is preferably performed 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 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 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. The reaction temperature is preferably 0 ° C. or higher and 90 ° 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.

When producing the composite fiber 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, salts, esters and ethers thereof, and alcohol-based surfactants. Activators, sorbitan fatty acid esters, amide and amine surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonylphenyl ether, sodium alphaolefin sulfonate, long chain alkyl amino acids, amine oxides, alkylamines, fourth A tertiary ammonium salt, an aminocarboxylic acid, a phosphonic acid, a polyvalent carboxylic acid, a condensed phosphoric acid 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.
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 by the conductivity of the reaction solution and the reaction time, and specifically, the time during which the reactant 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 making the reaction a multi-step reaction.

In the present invention, since the composite fiber which is a reaction product is obtained as a suspension, it may be stored in a storage tank or subjected to treatments such as concentration, dehydration, pulverization, classification, aging and dispersion as necessary. can do. These can be carried out by a known process, and may be appropriately determined in consideration of application, energy efficiency and the like. For example, the concentration / dehydration treatment is performed using a centrifugal dehydrator, a sedimentation concentrator, or the like. Examples of this centrifugal dehydrator include a decanter, a screw decanter, and the like. There is no particular limitation on the type of filter or dehydrator, and general ones can be used. For example, a pressurized dehydrator such as a filter press, a drum filter, a belt press, or a tube press can be used. A vacuum drum dehydrator such as an Oliver filter can be preferably used to prepare a calcium carbonate cake. 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. Examples of the classification method include a sieve such as a mesh, an outward type or inward type slit or round hole screen, a vibration screen, a heavy foreign matter cleaner, a lightweight foreign matter cleaner, a reverse cleaner, and a sieving tester. Examples of the dispersion method include a high-speed disperser and a low-speed kneader.

The composite fiber in the present invention can be blended with a filler or a pigment in a suspension state without being completely dehydrated, 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 composite fiber of 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 a resin or the like.

In the present invention, water is used for preparing a suspension, and as this water, ordinary tap water, industrial water, groundwater, well water, etc. can be used, as well as ion-exchanged water, distilled water, and super water. Pure water, industrial wastewater, and water obtained when separating and dehydrating the reaction solution can be preferably used.

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 promoting the stirring of the solution, the reaction efficiency is increased and it becomes easy to obtain a desired complex of inorganic particles and fibers.

Inorganic particles In the present invention, the inorganic particles to be composited with the fiber are not particularly limited, but are preferably water-insoluble or sparingly soluble inorganic particles. Since the synthesis of inorganic particles 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 particles are insoluble or sparingly soluble in water.

The inorganic particles referred to here refer to compounds of metal elements or non-metal elements. 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 particles is a metal salt of calcium, magnesium or barium, or at least a part of the inorganic particles is a metal salt of silicic acid or aluminum, or titanium, copper, silver, iron, manganese. , Cerium or zinc-containing metal particles are preferred.

The method for synthesizing these inorganic particles 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. Complex inorganic particles can be obtained. Further, when synthesizing the inorganic particles in this way, any metal or non-metal compound can coexist in the reaction solution, and in this case, those metals or non-metal compounds are efficiently incorporated into the inorganic particles. , Can be compounded. 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.

(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 blowing in _{to obtain calcium carbonate 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.

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 mixed with water to prepare, or quicklime (calcium oxide) is dissolved (digested) with water. Can be prepared. The conditions for reconstitution are not particularly limited, but for example, the concentration of CaO can be 0.05% 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.

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 high temperature, 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, in order to produce a composite fiber in which calcium carbonate is tightly bound, it is necessary to appropriately control the nucleation reaction. 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 0.20 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 complex cannot be obtained due to poor stirring. The _{amount of CO 2} supplied per hour is preferably 0.001 mol / min or more and less than 0.060 mol / min per 1 L of the reaction solution. If it is less than 0.001 mol / min, the reaction is difficult to proceed, and if it is 0.060 mol / min or more, inorganic particles liberated in the suspension are likely to be 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 carbon dioxide gas is refined by cavitation bubbles, so that the reaction can be efficiently performed. ..

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 gas containing carbon dioxide of the present invention may be a substantially pure carbon dioxide gas or a mixture with another gas. 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. 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, or 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, nuclei are not easily fixed to the cellulose fibers, and inorganic particles released 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 0.20 mol / L. If it is less than 0.0001 mol / L, the reaction is difficult to proceed, and if it is 0.20 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 complex cannot be obtained due to poor stirring. The _{amount of CO 2} supplied per hour is preferably 0.001 mol / min or more and less than 0.060 mol / min per 1 L of the reaction solution. If it is less than 0.001 mol / min, the reaction is difficult to proceed, and if it is 0.060 mol / min or more, inorganic particles liberated in the suspension are likely to be 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 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 complex cannot be obtained due to poor stirring. Supply amount per time of SO ₄ ions is desirably less than the reaction solution 1L per 0.005 mol / min or more 0.080 mol / min. If it is less than 0.001 mol / min, the reaction is difficult to proceed, and if it is 0.080 mol / min or more, inorganic particles liberated in the suspension are likely to be 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) is immersed. (Aqueous metal salt solution containing metal ions) is added, and the temperature, pH, etc. are controlled to synthesize hydrotalcite by a co-precipitation reaction. 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 it 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 carbonate ions are used as interlayer anions, 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 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 complex cannot be obtained due to poor stirring. The amount of metal ions supplied per hour depends on the type of metal, but in the case of Mg ions, for example, it is preferably 0.001 mol / min or more and less than 0.010 mol / min per 1 L of the reaction solution, and 0.001 mol / min or more and 0. More preferably less than .005 mol / min. If it is less than 0.001 mol / min, the reaction is difficult to proceed, and if it is 0.010 mol / min or more, inorganic particles liberated in the suspension are likely to be 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 sulfate band, aluminum chloride, polyaluminum chloride, alum, potassium alum and the like, and among them, the 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 ions, aluminum ions) in the reaction solution and the higher the temperature conditions, the easier the nucleation reaction proceeds. 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 complex cannot be obtained due to poor stirring. In the case of aluminum ions, for example, the amount of silicate ions and aluminum ions to be added per hour is preferably 0.001 mol / min or more, more preferably 0.01 mol / min or more, and 0.5 mol / min or more per 1 L of the reaction solution. Less than min is desirable, less than 0.050 mol / min is more desirable. If it is less than 0.001 mol / min, the reaction is difficult to proceed, and if it is 0.050 mol / min or more, inorganic particles liberated in the suspension are likely to be synthesized.

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

(Aluminum hydroxide)
Aluminum hydroxide is an ionic crystalline compound composed of an aluminum ion represented by Al (OH) ₃ and a hydroxide ion, and is often in a granular form and is sparingly soluble in water. Synthetic products produced by chemical reactions are used as pharmaceuticals and adsorbents, and are also used as flame-retardant agents and non-combustible agents by utilizing the property of releasing water when heated.

In the present invention, a composite of aluminum hydroxide and fiber can be produced by synthesizing aluminum hydroxide 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, aluminum hydroxide can be obtained by reacting sodium hydroxide with aluminum sulfate, or aluminum chloride can be added to an aqueous solution containing an alkali salt to precipitate aluminum hydroxide.

In the synthesis of aluminum hydroxide, the higher the concentration of the raw materials (Al ion, OH ion) in the solution and the higher the temperature condition, the easier the nucleation reaction proceeds. Under the above 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 aluminum hydroxide is tightly bound, it is necessary to appropriately control the nucleation reaction. Specifically, this can be achieved by optimizing the concentrations of OH ions and pulp and slackening the supply amount of Al ions per hour. For example, the OH ion concentration in the reaction vessel is preferably 0.01 mol / L or more and less than 0.50 mol / L. If it is less than 0.01 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 complex cannot be obtained due to poor stirring. The amount of Al ions supplied per hour is preferably 0.001 mol / min or more and less than 0.050 mol / min per 1 L of the reaction solution. If it is less than 0.001 mol / min, the reaction is difficult to proceed, and if it is 0.050 mol / min or more, inorganic particles liberated in the suspension are likely to be synthesized.

Cellulose fiber The composite fiber used in the present invention is a composite of cellulose fiber 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, cypress, larch, shirabe, spruce, hiba, douglas fur, hemlock, white fur, spruce, balsam fur, cedar, pine, Conifers such as merkushimatsu and radiata pine, and their mixed materials, beech, hippo, cypress, nara, tab, shii, white hippo, larch, poplar, fir, doroyanagi, eucalyptus, mangrove, lauan, acacia and other broadleaf 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 with 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 hemp, Manila hemp, flax, straw, bamboo, bagus, kenaf, sugar cane, corn, rice straw, kozo, and mitsumata.

The pulp fiber may be either unbeaten or beaten, and may be selected according to the physical characteristics of the complex 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 cellulose nanofibers: CNF (microfibrillated cellulose: MFC, TEMPO oxide CNF, phosphoric acid 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 and is produced by, for example, a method of purifying and drying an undecomposed residue obtained after acid-hydrolyzing selected pulp, pulverizing and sieving. 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 500 nm 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 above-mentioned 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 or beaten with a refiner, a high-pressure homogenizer, a grinder, a uniaxial or multiaxial kneader, a bead mill or the like. This makes it possible to use a method of defibrating. 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 preferably in the range of 5 nm to 300 nm, for example. 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, heptanoil group, octanoyl group, nonanoyl group. , Decanoyl group, undecanoyl group, dodecanoyl group, myristoyl 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 because they are easily applied industrially and easily gasified, but are not particularly limited. Further, the cellulose nanofibers may be modified in such a way that the compound to be modified physically adsorbs to the cellulose nanofibers without being chemically bonded. 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 defibration and / or pulverization of cellulose, these functional groups can be eliminated after defibration and / or pulverization to return to the original hydroxyl group. By applying the above modifications, it is possible to promote the defibration of the cellulose nanofibers and to facilitate mixing with various substances when the cellulose nanofibers are used.

The fibers shown above may be used alone or in combination of two or more. For example, the fibrous material 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 fiber to be composited 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, 400 μm to 8 mm, or the like. Of these, in the present invention, the average fiber length is preferably 400 μm or more (0.4 mm or more).

The average fiber diameter of the fibers to be composited is not particularly limited, but for example, the average fiber diameter can be about 1 nm to 100 μm, and may be 500 nm to 100 μm, 1 μm to 90 μm, 3 μm to 50 μm, 5 μm to 30 μm, or the like. Of these, in the present invention, it is preferable that the average fiber diameter is 500 nm or more because the production efficiency in the subsequent process can be improved.

The average fiber length and average fiber diameter of the fiber can be measured by a fiber length measuring device. Examples of the fiber length measuring device include Valmet Fractionator (manufactured by Valmet).

The composite fiber is preferably used in an amount such that 15% or more of the fiber surface is covered with inorganic particles. For example, the weight ratio of the fiber to the inorganic particles is 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 a preferred embodiment, the composite fiber according to the present invention has 15% or more of the fiber surface coated with inorganic particles, and if the surface of the cellulose fiber is coated with such an area ratio, the feature caused by the inorganic particles is large. On the other hand, the features due to the fiber surface become smaller.

The composite fiber according to the present invention can be used in various shapes, for example, powder, pellets, molds, aqueous suspensions, pastes, sheets, boards, blocks, and other shapes. Further, it is also possible to form a molded product such as a mold or particles / pellets by using a composite fiber as a main component 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, or the like can be preferably used.

The composite fiber according to 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, tire, building. Materials (asphalt, asbestos, cement, boards, concrete, bricks, tiles, plywood, fiberboards, ceiling materials, wall materials, flooring materials, roofing materials, etc.), furniture, various carriers (catalyst carriers, pharmaceutical carriers, pesticide carriers, microorganisms, etc.) Carriers, etc.), adsorbents (impurity removal, deodorization, dehumidification, etc.), antibacterial materials, antiviral agents, wrinkle inhibitors, clay, abrasives, friction materials, modifiers, repair materials, heat insulating materials, heat resistant materials, heat dissipation Materials, moisture-proof materials, water-repellent materials, water-resistant materials, light-shielding materials, sealants, shield materials, insect repellents, adhesives, medical materials, paste materials, discoloration inhibitors, radio wave absorbers, insulating materials, sound insulation materials, interior materials, It can be widely used in all applications such as vibration materials, semiconductor encapsulants, radiation blocking materials, and materials. Further, it can be used as various fillers, coating agents and the like in the above-mentioned applications. Of these, adsorbents, antibacterial materials, antiviral agents, friction materials, radiation shielding materials, flame-retardant materials, building materials, and heat insulating materials are preferable.

The composite fiber of 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, and high-quality color. 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, flame-retardant paper (non-combustible 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 plate base paper, Examples include cup base paper, baking paper, abrasive paper, and synthetic paper. That is, according to the present invention, it is possible to obtain a composite of inorganic particles having a small primary particle diameter and a narrow particle size distribution and fibers, which is different from the conventional inorganic filler having a particle diameter of more than 2 μm. It is possible to exert the characteristics. Furthermore, unlike the case where the inorganic particles are simply blended with the fiber, if the inorganic particles are complexed with the fiber, not only the inorganic particles can be easily retained on the sheet, but also the sheet is uniformly dispersed without agglomeration. Obtainable. It has been clarified from the results of electron microscopic observation that the inorganic particles in the present invention are formed not only on the outer surface of the fiber and inside the lumen but also on the inside of the microfibril in a preferable embodiment.

Further, when using the composite fiber according to the present invention, particles generally called inorganic filler and organic filler, 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, in addition to calcium carbonate and / or a light calcium carbonate-silica composite, amorphous silica such as white carbon may be used in combination. 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-based fibers such as wool, silk thread and collagen fiber, and composite sugar chain-based fibers such as chitin / chitosan fiber and alginic acid fiber. Examples of the cellulosic 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, cypress, larch, shirabe, spruce, hiba, douglas fur, hemlock, white fur, spruce, balsam fur, cedar, pine, Conifers such as merkushimatsu and radiata pine, and their mixed materials, beech, hippo, cypress, nara, tab, shii, white hippo, larch, poplar, fir, doroyanagi, eucalyptus, mangrove, lauan, acacia and other broadleaf 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 with 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 hemp, Manila hemp, flax, straw, bamboo, bagus, 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, phosphoric acid 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 average particle size, shape, etc. of the inorganic particles constituting the composite fiber of the present invention can be confirmed by observation with an electron microscope. Furthermore, by adjusting the conditions for synthesizing the inorganic particles, the inorganic particles having various sizes and shapes can be complexed with the fibers.

Form of Composite Fiber In the present invention, the above-mentioned composite fiber can be molded into various molded products (body). For example, when the composite fiber of 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 pasted together to form a multi-layer sheet.

Examples of the paper machine (paper machine) used for sheet production include a long net paper machine, a circular net paper machine, a gap former, a hybrid former, a rotoformer, a multi-layer paper machine, and a known paper machine that combines the paper making methods of these devices. Can be mentioned. The press line pressure in the paper machine and the calendar line pressure when the calendar processing is performed in the subsequent stage can be set within a range that does not affect the operability and the performance of the composite fiber sheet. Further, starch, various polymers, pigments and mixtures thereof may be applied to the formed sheet by impregnation or coating.

At the time of sheeting, a wet and / or dry paper strength agent (paper strength enhancer) can be added. Thereby, the strength of the composite fiber 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, mannogalactanpolyethyleneimine, polyacrylamide resin, and polyvinylamine. , Polyvinyl alcohol and the like; composite polymers or copolymers composed of two or more kinds selected from the above resins; starch and processed starch; carboxymethyl cellulose, guar gum, urea resin 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 modified products, 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. And an acrylate ester are copolymerized with each other, and then a quaternary ammonium salt is mentioned. 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.

The basic weight of the sheet (basis weight: weight per square meter) can be adjusted as appropriate according to the purpose, but when used as a building material, for example, 60 to 1200 g / m ² is strong and at the time of manufacture. It is good because the drying load is low. Further, the basis weight of the sheet ^{can be 1200 g / m 2} or more, for example, 2000 to 110000 g / m ² .

It is also possible to use a molding method other than sheeting. For example, a method called a pulp mold in which a raw material is poured into a mold and suction-dehydrated / dried, or a method of spreading and drying on the surface of a molded product such as resin or metal is used. 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 mixed with a resin and molded into a plastic shape, or it can be mixed with cement or rubber and used as a reinforcing material. Further, it can be formed into a board shape or a block shape by pressure / heat press molding which is generally used for making an inorganic board such as cement or gypsum. Generally, the sheet can be bent or rolled up, but can be made into a board if more strength is required. It can also be molded into a block shape, which is a thick mass, and can be molded into, for example, a rectangular parallelepiped or a cube.

In the above-mentioned compounding, drying, and molding, only one type of complex can be used, or two or more types of complexes can be mixed and used. When two or more types of complexes are used, those that are mixed in advance can be used, or those that are mixed, dried, and molded can be mixed later.

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

Printing can be applied to the molded product produced by the product of the present invention. This printing method is not particularly limited, but for example, offset printing, silk screen printing, screen printing, gravure printing, micro gravure printing, flexo printing, typographic printing, sticker printing, form printing, on-demand printing, fanniquet. It can be performed by a known method such as shear roll printing or inkjet printing. Among these, ink jet printing is preferable because it is not necessary to prepare a block copy unlike offset printing, and it is relatively easy to increase the size of an inkjet printer, so that printing on a large sheet is also possible. Further, since flexographic printing can be suitably used for molded products having relatively large surface irregularities, it can also be suitably used when molded into a shape such as a board, a mold, or a block.

Further, the type of the pattern of the printed image formed by printing is not particularly limited, and for example, a wood grain pattern, a stone grain pattern, a cloth grain pattern, an abstract pattern, a geometric pattern, characters, symbols, or a combination thereof, etc. It is optional, and may be a solid color.

The present invention will be described in more detail with reference to specific experimental examples, but the present invention is not limited to the following specific examples. Further, unless otherwise specified in the present specification, the concentration, parts, etc. are based on weight, and the numerical range is described as including the end points thereof.

Experiment 1. Composite synthesis 1-1. Composite fiber of barium sulfate and cellulose fiber (Sample 1, FIG. 1)
3 One Motor (500 rpm) 1% pulp slurry (LBKP, CSF = 450 mL, average fiber length: about 0.7 mm, average fiber diameter: about 19 μm) 436 g and barium hydroxide octahydrate (Nippon Kagaku Kogyo) 18.8 g ), Then aluminum sulfate (sulfate band stock solution, 25.8 g) was added dropwise at 0.4 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain Sample 1.

(Sample 2, Fig. 2)
Three-One Motor with 1.7% pulp slurry (LBKP, CSF = 450 mL, average fiber length: about 0.7 mm, average fiber diameter: about 19 μm) 533 g and barium hydroxide octahydrate (Nippon Kagaku Kogyo) 12.4 g After mixing at (667 rpm), aluminum sulfate (4-fold diluted aqueous solution of sulfate band stock solution, 67.2 g) was added dropwise at 1.1 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain Sample 2.

(Sample 3, Fig. 3)
3 One Motor (500 rpm) 1% pulp slurry (NBKP, CSF = 425 mL, average fiber length: about 1.7 mm, average fiber diameter: about 26 μm) 437 g and barium hydroxide octahydrate (Nippon Kagaku Kogyo) 18.8 g ), Then aluminum sulfate (sulfate band stock solution, 26.1 g) was added dropwise at 0.4 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain Sample 3.

(Sample 4, Fig. 4)
3 One Motor (500 rpm) 1% pulp slurry (LBKP, CSF = 450 mL, average fiber length: about 0.7 mm, average fiber diameter: about 19 μm) 436 g and barium hydroxide octahydrate (Nippon Kagaku Kogyo) 18.8 g ), Then aluminum sulfate (sulfate band stock solution, 25.8 g) was added dropwise at 1.0 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a complex slurry.

(Sample 5, Fig. 5, inorganic particles only)
After mixing 437 g of water and barium hydroxide octahydrate (Nippon Chemical Industrial Co., Ltd., 18.8 g) in a 2 L container with a three-one motor (500 rpm), add aluminum sulfate (sulfate band stock solution, 25.8 g) at 1.0 g / min. Dropped. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample of barium sulfate particles.

(Sample 6, Fig. 6, mixture of inorganic particles and cellulose fibers)
After mixing 121 g of sample 6 barium sulfate particle slurry (concentration 3.0%) with 120 g of 1% pulp slurry (LBKP, CSF = 450 mL, average fiber length: about 0.7 mm, average fiber diameter: about 19 μm). Water was added and stirred to obtain a mixed slurry of barium sulfate and cellulose fibers.

(Sample 7, Fig. 7)
500 g of 1% pulp slurry (LBKP / NBKP = 8/2, average fiber length: about 1.2 mm, average fiber diameter: about 14 μm) and 5.82 g of barium hydroxide octahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) After mixing with a three-one motor (1000 rpm), sulfuric acid (Fujifilm Wako Pure Chemical Industries, Ltd., 2.1 g) was added dropwise at 0.8 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample of the complex slurry.

(Sample 8, Fig. 8)
500 g of 1% pulp slurry (LBKP / NBKP = 8/2, average fiber length: about 1.2 mm, average fiber diameter: about 14 μm) and 5.82 g of barium hydroxide octahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) After mixing with a three-one motor (1000 rpm), sulfuric acid (Fujifilm Wako Pure Chemical Industries, Ltd., 2.1 g) was added dropwise at 63.0 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample of the complex slurry.

(Sample 9, Fig. 9)
500 g of 1% pulp slurry (LBKP / NBKP = 8/2, average fiber length: about 1.2 mm, average fiber diameter: about 14 μm) and 5.82 g of barium hydroxide octahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) After mixing with a three-one motor (1000 rpm), sulfuric acid (Fujifilm Wako Pure Chemical Industries, Ltd., 2% aqueous solution (88 g)) was added dropwise at 8.0 g / min. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample of the complex slurry.

(Sample 10, FIG. 10)
1% pulp slurry (LBKP / NBKP = 8/2, Canadian standard drainage CSF = about 80 mL, average fiber length: 1.21 mm, 500 g) and barium hydroxide octahydrate (Wako Pure Chemicals, 5.82 g) ) Was mixed with stirring by a three-one motor (1000 rpm), and then sulfuric acid (88 g of Wako pure drug, 2% aqueous solution) was added dropwise at 8 g / min with a perister pump. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample. When observed with an electron microscope, it was confirmed that the plate-shaped barium sulfate self-fixed on the fiber surface and covered the fiber surface (primary particle size of barium sulfate particles: 200 to 1500 nm, average primary of barium sulfate particles). Particle size: 500 nm).

(Sample 11, FIG. 11)
After mixing 1% pulp slurry (LBKP, CSF = 500 mL, average fiber length: about 0.7 mm, 1300 g) and barium hydroxide octahydrate (Wako Pure Chemical, 57 g) with stirring with a three-one motor (800 rpm). , Aluminum sulfate (sulfate band, 77 g) was added dropwise at 2 g / min with a perister pump. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample. When observed with an electron microscope, it was confirmed that the plate-shaped barium sulfate self-fixed on the fiber surface and covered the fiber surface (primary particle size of barium sulfate particles: 20 to 800 nm, average primary of barium sulfate particles). Particle size: 100 nm).

(Sample 12, FIG. 12)
2% pulp slurry (LBKP / NBKP = 8/2, CSF = 390 mL, average fiber length: about 1.3 mm, solid content 25 kg) and barium hydroxide octahydrate in a container (machine chest, volume: 4 m ³⁾ (Nippon Chemical Industrial Co., Ltd., 75 kg) was added and mixed, and then aluminum sulfate (sulfate band, 98 kg) was added dropwise at about 500 g / min using a perister pump. After completion of the dropping, stirring was continued for 30 minutes as it was to obtain a sample. When observed with an electron microscope, it was confirmed that the plate-shaped barium sulfate self-fixed on the fiber surface and covered the fiber surface (primary particle size of barium sulfate particles: 50 to 1000 nm, average primary of barium sulfate particles). Particle size: 80 nm).

1-2. Composite fiber of Al hydroxide and cellulose fiber (Sample A, FIG. 13)
1% pulp slurry (LBKP, CSF = 450 mL, average fiber length: about 0.7 mm, average fiber diameter: about 19 μm) 437 g and sodium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd.) 4.8 g with a three-one motor (500 rpm) After mixing, aluminum sulfate (sulfate band stock solution, 25.8 g) was added dropwise at 0.8 g / min. After completion of the dropping, the reaction solution was stirred for 30 minutes and washed with about 3 times the amount of water to remove the salt to obtain Sample A.

1-3. Composite fiber of silica / alumina and cellulose fiber (Sample B, FIG. 14)
910 g of 0.5% pulp slurry (NBKP, CSF: 360 mL, average fiber length: about 1.7 mm, average fiber diameter: about 18 μm) was placed in a 2 L resin container and stirred with a laboratory mixer (600 rpm). Aluminum sulfate (sulfate band stock solution) was added dropwise to this aqueous suspension for about 4 minutes until pH = 3.8, and then aluminum sulfate (sulfate band, 156 g) and an aqueous sodium silicate solution (Fujifilm Wako Pure Chemical Industries, Ltd., concentration) were added. 8%, 265 g) was added dropwise simultaneously for about 60 minutes to maintain pH = 4. A perister pump was used for dropping, and the reaction temperature was about 25 ° C. Then, only the sodium silicate aqueous solution (Fujifilm Wako Pure Chemical Industries, Ltd., concentration 8%, 200 g) was added dropwise for about 80 minutes to adjust the pH to 7.3 to obtain a sample of the complex slurry.

1-4. Composite fiber of hydrotalcite and cellulose fiber (Sample C1, FIG. 15)
As a solution for synthesizing hydrotalcite (HT), _{a mixed aqueous solution (acid solution) of sulfonyl 4} (Fujifilm Wako Pure Chemical Industries, Ltd.) and Al ₂ (SO ₄ ) ₃ (Fujifilm Wako Pure Chemical Industries, Ltd.) was prepared. _{The concentration of sulfonyl 4} is 0.6M, and the concentration of Al ₂ (SO ₄ ) ₃ is 0.1M.

2.0% pulp slurry (NBKP, CSF = 270 mL, average fiber length: about 1.8 mm, average fiber diameter: about 19 μm) 2250 g, 88.6 g of sodium hydroxide (Fujifilm Wako Pure Chemical Industries, Ltd.) and sodium carbonate (Fuji) 14.8 g of (Film Wako Pure Chemical Industries, Ltd.) was added, mixed with a three-one motor (650 rpm), and then 1362 g of an acid solution was added dropwise at 4.7 g / min while maintaining the temperature at 50 ° C. After completion of the dropping, the reaction solution was stirred for 30 minutes and washed with about 3 times the amount of water to remove salts to obtain a sample.

(Sample C2, FIG. 16)
1.6% pulp slurry (NBKP, CSF = 690 mL, average fiber length: about 1.9 mm, average fiber diameter: about 19 μm) 2281 g, sodium hydroxide (Fuji Film Wako Pure Chemical Industries, Ltd.) 88.6 g and sodium carbonate (Fuji) 14.8 g of (Film Wako Pure Chemical Industries, Ltd.) was added, mixed with a three-one motor (650 rpm), and then 1322 g of an acid solution was added dropwise at 4.6 g / min while maintaining the temperature at 50 ° C. After completion of the dropping, the reaction solution was stirred for 30 minutes, washed with water using about 3 times the amount of water to remove salt, and then suction-dehydrated with a filter paper to obtain a sample (solid content concentration: about 35%). ).

1-5. Composite fiber of calcium carbonate and cellulose fiber (Sample D1, FIG. 17)
Aqueous suspension containing calcium hydroxide (slaked lime: Ca (OH) ₂ , 100 g, Fujifilm Wako Pure Chemical Industries, Ltd.) and powdered cellulose (KC Flock ™ W-06MG, manufactured by Nippon Paper Co., Ltd., average particle size: 6 μm, 100 g) 10 L of liquid was prepared. This aqueous suspension was placed in a 40 L volume sealing device, carbon dioxide gas was blown into the reaction vessel to generate cavitation, and composite fibers of calcium carbonate fine particles and fibers were synthesized by the carbon dioxide gas method. The reaction temperature was about 15 ° C., the carbon dioxide gas was supplied from a commercially available liquefied gas, the amount of carbon dioxide gas blown was 3 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).

In the synthesis of composite fibers, cavitation bubbles were generated in the reaction vessel by circulating the reaction solution and injecting it into the reaction vessel. Specifically, 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.

(Sample D2, FIG. 18)
Composite fibers were synthesized in the same manner as in Sample D1 except that the powdered cellulose used was W-100G (manufactured by Nippon Paper Industries, average particle size: 37 μm) and the amount of carbon dioxide gas blown was 20 L / min.

Experiment 2. Evaluation of complex sample 2-1. Evaluation of coverage, etc. Each of the obtained complex samples was washed with ethanol and then observed with an electron microscope. As a result, it was observed that the fiber surface was covered with an inorganic substance and self-fixed in all the samples. The coverage of each complex sample is shown in the table, and the coverage was 15% or more in each case.

Further, after suction-filtering the obtained composite fiber slurry (3 g in terms of solid content) with a filter paper, the residue is dried in an oven (105 ° C., 2 hours), and the ash content is measured to measure the inorganic particles in the composite fiber. The weight ratio of was measured.

For the average fiber length and average fiber diameter of the fibers, the values measured by Valmet Fractionator are described as the fiber length. When measuring the fiber length, the solid content concentration of the slurry was adjusted to 0.1 to 0.3%, and the water temperature in the apparatus was adjusted to 25 ° C. ± 1 ° C. for the measurement.

2-2. Evaluation by sieving / automatic classification <Sieving of complex samples>
Filtration with a mesh filter was performed to remove coarse particles in the synthesized slurry. The obtained complex sample (1 g in terms of solid content) was diluted with water so that the solid content concentration was 0.1%, and 0.2 liter of the suspension was sieved through a 60 mesh (opening 250 μm) sieve. All were filtered and washed with 0.6 liters of water. Next, the particle size distribution (Mastersizer 3000, manufactured by Malvern) was measured for the filtered filtrate after filtration by a wet method.

<Automatic classification of complex samples>
In addition to sieving, a fiber classification analyzer (Valmet Fractionator) was used as a method for automatically classifying a sample into a plurality of fractions under certain conditions. This device flows pulp slurry into a tube with a length of about 100 m at a constant temperature and constant velocity, separates long fibers into fine fibers / fillers according to the hydrodynamic size, and then automatically performs five fractions (FR1) according to the outflow time. ~ 3: Long / short fiber, FR4 ~ 5: Fine fiber / filler).

Specifically, the complex sample (3 g in terms of solid content) was diluted with water so that the solid content concentration was 0.3%, and about 250 g each was poured into a fiber classification analyzer in 3 portions. Fractions fractionated under the outflow conditions were collected (water temperature at the time of classification 25 ± 1 ° C.).

The recovered FR4 was allowed to stand in a bucket for several hours to allow the fibers to settle, and after removing the supernatant, the particle size distribution (Mastersizer 3000, manufactured by Malvern) was measured by a wet method.

<Particle size distribution>
The numerical value of "(D50-D10) / D50" was calculated from D10 (cumulative particle size of 10%) and D50 (cumulative particle size of 50%) in the volume-based particle size distribution measured as described above. The smaller this value is, the narrower the particle size distribution of the sample is, which means that the inorganic substance is firmly fixed on the fiber surface.

2-3. Yield evaluation in sheeting From the obtained composite samples (Samples 1 to 12 and Sample A), hand-cut to a basis weight of 100 g / m ^{2 using a 150 mesh wire according to JIS P 8222: 2015.} A sheet was prepared, and the paper yield was calculated from the basis weight of the obtained sheet.
〇: 70% or more Δ: 50% or more and less than 70% ×: less than 50%

2-4. Evaluation of drainage The obtained complex samples (Samples 1 to 12 and Sample A) were diluted with water so that the solid content concentration was 0.1%, and the solid content of the inorganic substance was 0. The transit time when the slurry prepared to be 15 g was passed through a membrane filter (0.8 μm) under a reduced pressure of 20 mmHg was measured.
⊚: Less than 2 minutes 〇: 2 minutes or more and less than 4 minutes △: 4 minutes or more and less than 6 minutes ×: 6 minutes or more

As is clear from the table, it was found that the composite fiber samples 1 to 3 and 9 having a relatively large D50 of the filtrate after classification had a higher yield at the time of sheeting as compared with the samples 4 to 8. This indicates that functional inorganic particles can be highly blended in the sheet, and it can be said that the sheet is excellent in terms of functional quality in addition to high production efficiency.

Further, in the evaluation of drainage assuming the case of producing a sheet containing the same amount of inorganic particles, the composite fiber samples 1 to 3 and 9 are only the composite fiber samples 4, 7, 8, 10 to 12, and the inorganic particles. It was found that the dehydration rate was faster than that of Sample 5 and Mixture Sample 6. It is considered that this is because the composite fiber samples 1 to 3 and 9 have relatively few fine particles that affect the drainage. If the drainage is good, the drying process can be shortened and alleviated, which leads to an improvement in productivity (reducing the frequency of paper breaks and increasing the speed of paper making) when manufacturing sheets, and particularly thick sheets are manufactured. It can be said that the effect is great in some cases.

Claims

A method for producing composite fibers of cellulose fibers and inorganic particles.
The process of synthesizing inorganic particles in a solution containing cellulose fibers to obtain composite fibers,
The following (a) or (b):
(A) A filtrate obtained by filtering an aqueous suspension of composite fibers having a solid content concentration of 0.1% with a sieve of 60 mesh (opening 250 μm).
(B) An aqueous suspension of composite fibers having a solid content concentration of 0.3% was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total outflow of 22 L. Fractions corresponding to the outflow amount (L) 18.51 to 19.50 and the outflow time (sec) 37.4 to 48.0.
To calculate (D50-D10) / D50 by measuring the particle size distribution of
The above method, including.
The method according to claim 1, wherein the aqueous suspension of the composite fiber is prepared so that (D50-D10) / D50 is 0.85 or less.
The method according to claim 1 or 2, wherein the average fiber diameter of the composite fiber is 500 nm or more.
The method according to any one of claims 1 to 3, wherein the inorganic particles contain a metal salt of calcium, magnesium, barium or aluminum, metal particles containing titanium, copper or zinc, or a silicate.
A method for producing a composite fiber sheet, which comprises a step of forming a sheet from the composite fiber obtained by any of the methods 1 to 4.
It is a composite fiber of a cellulose fiber and an inorganic particle, and is described in (a) or (b) below:
(A) A filtrate obtained by filtering an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve having a solid content of 0.3% (b) of a composite fiber having a solid content concentration of 0.3%. When the aqueous suspension was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total runoff of 22 L, the runoff (L) 18.51-19. 50, Fraction corresponding to outflow time (sec) 37.4-48.0,
The composite fiber having a value of (D50-D10) / D50 calculated from the particle size distribution of 0.85 or less.
A composite fiber of cellulose fibers and inorganic particles obtained by treating an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve of 60 mesh (opening 250 μm) and passing through the sieve.
The composite fiber having a (D50-D10) / D50 value of 0.85 or less calculated from the particle size distribution of the filtrate that has passed through the sieve.
An aqueous suspension of composite fibers having a solid content concentration of 0.3% was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total outflow amount of 22 L, and the outflow amount was obtained. (L) 18.51 to 19.50, a composite fiber of cellulose fibers and inorganic particles obtained from a fraction corresponding to an outflow time (sec) of 37.4 to 48.0.
The composite fiber having a value of (D50-D10) / D50 calculated from the particle size distribution of the fraction of 0.85 or less.
A method for analyzing a composite fiber of cellulose fibers and inorganic particles, wherein the following (a) or (b):
(A) A filtrate obtained by filtering an aqueous suspension of a composite fiber having a solid content concentration of 0.1% with a sieve having a solid content of 0.3% (b) of a composite fiber having a solid content concentration of 0.3%. When the aqueous suspension was classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L / min, a water temperature of 25 ± 1 ° C., and a total runoff of 22 L, the runoff (L) 18.51-19. 50, Fraction corresponding to outflow time (sec) 37.4-48.0,
The above method comprising the step of measuring the particle size distribution of (D50-D10) / D50 and calculating (D50-D10) / D50.