JP7824501B2 - Method for producing fiber paper with high content of micro-sized material - Google Patents

Description

The present invention aims to provide a fiber paper and a method for manufacturing the same that can contain a high composition ratio of fine-sized materials (average particle diameter: 1 nm to 9000 nm) while using conventional wet papermaking equipment and techniques by adjusting the size of the aggregates of the fiber paper material to a size suitable for wet papermaking production without using special chemicals or equipment, even though it is considered difficult to adjust the size of the aggregates of the fiber paper material to a size suitable for wet papermaking production in fiber paper manufactured by the wet papermaking method.

Recently, the development of micro-sized functional materials, including cellulose nanofibers (CNF) and carbon nanotubes (CNT), has been progressing rapidly. Furthermore, these micro-sized materials may exhibit unique physical properties (e.g., high strength, high elasticity, and high conductivity) and chemical functions (e.g., high molecular adsorption performance and high flame retardancy) that are not observed in large-sized materials (average particle diameter of 10 μm or more). For this reason, products containing high proportions of these micro-sized materials are currently being developed. This trend is also evident in the nonwoven fabric industry, where reports have been published on nonwoven fabrics using the cellulose nanofibers and carbon nanotubes, as well as on methods for producing such fabrics.

In particular, with regard to nonwoven fabrics containing micro-sized materials and methods for producing the same, Patent Document 1 introduces a method in which a functional micro-sized material is applied to fiber paper by a printing method such as an inkjet method, and then the applied material is exposed to high-power pulsed photons (such as ultraviolet light or microwaves) to activate the material whose functionality has been deactivated or reduced within the coating film. Patent Document 2 also reports a method in which a micro-sized material such as cellulose nanofibers is dissolved and spray-coated. Furthermore, as an example of fiber paper produced by a wet papermaking method, Patent Document 3 reports various methods in which a synthetic fiber nonwoven fabric (fiber paper) is impregnated with a micro-sized material made of functional metal ions such as Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn, and Cu supported on cellulosic fibers having carboxyl or carboxylate groups on the surface. However, the fiber paper and the manufacturing method thereof described in Patent Document 1 and Patent Document 2 contain the micro-sized material only near the surface of the fiber paper, and it is not possible to contain the micro-sized material throughout the fiber paper, and it is difficult to achieve a quantitative effect of the micro-sized material when used as a filter material, etc. Furthermore, in the method of making paper from fibers carrying the micro-sized material, as in Patent Document 3, there is a limit to the amount of the micro-sized material carried relative to the fiber, making it difficult to contain the micro-sized material in a high composition ratio in the fiber paper.

Special Publication No. 2008-522369 Japanese Patent Application Laid-Open No. 2021-035468 JP 2017-155364 A

The present invention addresses the specific problems described in paragraphs "0002" to "0004" that exist in fiber paper manufacturing methods that contain a high proportion of micro-sized materials, by providing fiber paper that contains a high proportion of micro-sized materials but does not require special equipment and can be manufactured using a conventional manufacturing method of wet-laid aggregates, and a manufacturing method thereof.

Hereinafter, aggregation and fixation in the present invention means that micro-sized materials and materials other than the micro-sized materials uniformly dispersed in water aggregate to form larger particles in the dispersion due to the difference in potential with the aggregation binder and/or colloidal particles and the action of van der Waals forces, and that within these aggregated particles, the individual materials (micro-sized materials, materials other than the micro-sized materials, aggregation binder, colloidal particles, and auxiliary agents) do not easily separate, forming a stable state (aggregate).

Hereinafter, the average particle size in the present invention means the particle size of each particle of a micro-sized material, an aggregate particle (an aggregate particle: an aggregate particle formed by dispersing a micro-sized material, a material other than a micro-sized material, an aggregation binder, and colloidal particles in water, and then aggregating and fixing the particles), and a colloidal particle, measured by the following measurement method.
(Method for measuring average particle size)
(1) A TEM image of each of the particles is obtained using a transmission electron microscope (hereinafter abbreviated as TEM).
(2) From the TEM image of each particle, 100 individual particles are randomly selected, and the unidirectional diameter (projected diameter) is measured.
(3) The average particle size of the present invention is the arithmetic mean value of the measured unidirectional diameters (projected diameters) of 100 individual particles.

Furthermore, in the present invention, the mass percentages of the micro-sized material, materials other than the micro-sized material, the aggregation binder, and the colloidal particles are all based on the dry mass, and the mass percentages indicate the mass ratio to the dry mass of the entire fiber paper.

A fiber paper manufactured by a wet papermaking method, the fiber paper containing 50% by mass or more of micro-sized materials having an average particle size ranging from 1 nm to 9000 nm, based on the dry mass of the entire fiber paper, the fiber paper being manufactured by a manufacturing method consisting of the following three steps: a first step of preparing a liquid in which the micro-sized materials and materials other than the micro-sized materials are dispersed in water; a second step of adding an aggregation binder and colloidal particles having an average particle size ranging from 5 nm to 1000 nm to the liquid, and aggregating and fixing the micro-sized materials, materials other than the micro-sized materials, the aggregation binder, and the colloidal particles in the liquid to form aggregates having an average particle size ranging from 20 μm to 500 μm, thereby forming a liquid containing the aggregates; and a third step of wet papermaking the liquid obtained in the second step. (Claim 1) The fiber paper described in claim 1, wherein the micro-sized materials are zeolite having a particle size ranging from 50 nm to 200 nm. The fiber paper according to any one of claims 1 to 2, wherein the colloidal particles are inorganic particles having a particle diameter in the range of 5 nm to 1000 nm (claim 3). The fiber paper according to any one of claims 1 to 3, wherein the colloidal particles are alumina hydrate particles having a particle diameter in the range of 5 nm to 1000 nm and having a feather shape (claim 4). A method for producing fiber paper by a wet papermaking method, wherein the fiber paper contains 50% by mass or more of micro-sized materials having an average particle diameter in the range of 1 nm to 9000 nm relative to the dry mass of the entire fiber paper, and the first step is to prepare a liquid by dispersing the micro-sized materials and materials other than the micro-sized materials in water; the second step is to add an aggregation binder and colloidal particles having an average particle diameter in the range of 5 nm to 1000 nm to the liquid, and aggregate and fix the micro-sized materials, materials other than the micro-sized materials, the aggregation binder, and the colloidal particles in the liquid to form aggregates having an average particle diameter in the range of 20 μm to 500 μm, thereby forming a liquid containing the aggregates; and the third step is to wet papermake the liquid obtained in the second step, wherein the method for producing fiber paper comprises the first to third steps (claim 5). The method for producing fiber paper according to claim 5, wherein the micro-sized material is zeolite having a particle diameter in the range of 50 nm to 200 nm (claim 6). The method for producing fiber paper according to any one of claims 5 to 6, wherein the colloidal particles are inorganic particles having a particle diameter in the range of 5 nm to 1000 nm (claim 7). The method for producing fiber paper according to any one of claims 5 to 7, wherein the colloidal particles are alumina hydrate particles having a particle diameter in the range of 5 nm to 1000 nm and having a feather shape (claim 8).

When micro-sized materials with various functions are made into paper using a wet papermaking method, colloidal particles with an average particle size of 5 nm to 1000 nm are aggregated and fixed to the micro-sized materials dispersed in water and materials other than the micro-sized materials, thereby making it possible to produce aggregates with an average particle size of 20 μm to 500 μm.This does not require special equipment, there are no restrictions on manufacturing conditions, and the aggregates can be generated and grown to an appropriate size without using special chemicals, making it possible to realize fiber paper containing a high composition ratio of micro-sized materials and a manufacturing method for the same using conventional wet papermaking equipment and techniques.

The present inventors have investigated the problem described in paragraph "0005" and found that in a typical wet papermaking process, a fine-sized material having a particle size of 1 nm to 9000 nm and materials other than the fine-sized material (such as fibers and fillers) are simultaneously dispersed in water, and then the materials, the fine-sized material, and the colloidal particles are aggregated and fixed by an aggregation binder and colloidal particles (e.g., alumina hydrate) to form and grow aggregates. The use of an aggregation binder and colloidal particles in this way has led to the formation of aggregates large enough to produce fiber paper by conventional wet papermaking while still containing a high proportion of fine-sized materials.

In the method of the present invention, the size of the aggregate particles formed during aggregation is increased by using an aggregation binder and specific colloidal particles as a flocculant and fixative for each of the micro-sized materials and non-micro-sized materials dispersed in water. In conventional wet papermaking processes, cationic ions such as aluminum polysulfate are typically used as fixatives (in this case, aluminum ions). In this case, the particle size of the fixative is significantly smaller than that of the micro-sized materials being aggregated. (For example, the ionic radius of aluminum ions is 0.038 nm.) Therefore, the average particle size of the aggregate particles formed and grown by aggregation using these cationic ions is limited by the average particle size of the primary micro-sized material. On the other hand, when colloidal particles are used, the particle size of the colloidal particles is approximately the same as that of the micro-sized materials, ranging from 5 nm to 1000 nm, and is approximately 100 to 1000 times larger than that of cationic ions such as aluminum ions. Therefore, when aggregation is performed, aggregate particles are generated and grow to the size of colloidal particles, and the aggregate particles are generated and grow larger than when cationic ions are used. As a result, the average particle size of the aggregate particles becomes large enough to enable good wetlaid papermaking.

The aggregates obtained in the above paragraph "0012" have a particle size ranging from 20 μm to 500 μm. Aggregates of this size do not pass through the mesh of the papermaking machine used in conventional wet papermaking processes (mesh openings: various mesh openings can be selected from the range of 15 μm to 600 μm), resulting in a high production yield of fiber paper. Furthermore, the formation of a fiber layer on the mesh is prevented due to poor drainage caused by clogging of the mesh by minute aggregates. Furthermore, because the size of the aggregate particles is appropriate, the drainage state during the formation of the fiber layer on the mesh is improved, making it easier to increase the papermaking speed and improving production efficiency.

For this reason, the fiber paper of the present invention is highly effective when used for adsorption purposes or building materials. In adsorption applications, nano-order-sized adsorbents, which have a larger specific surface area, have significantly improved adsorption capacity compared to micro-order-sized adsorbents. However, it has been difficult to incorporate nano-order-sized adsorbents, which are minute-sized materials, into fiber paper at high compositional ratios. The fiber paper of the present invention can contain nano-order-sized adsorbents at high compositional ratios of 50% by mass or more, and can even contain up to 80% by mass. Therefore, by applying the fiber paper of the present invention to adsorbent paper such as activated carbon paper, zeolite paper, and silica gel paper, the adsorption efficiency of the adsorbent paper can be greatly improved.

In addition, for building materials, by increasing the content of nano-sized flame retardants, the specific surface area of the flame retardant can be increased, making it possible to produce fiber paper with higher flame retardancy. Therefore, in the future, it can be used for building materials (wallpaper, etc.) that require higher flame retardancy.

The micro-sized material in the present invention has an average particle diameter of 1 nm to 9000 nm and can be organic or inorganic. For example, in the case of inorganic materials, metals, oxides, nitrides, fluorides, carbides, and sulfides are preferably used. For example, metal materials include elemental metals such as iron, nickel, cobalt, copper, gold, and silver, as well as alloys such as nickel-tungsten. Examples of oxides that can be used include titanium oxide, zinc oxide, zirconium oxide, yttrium trioxide, and tungsten trioxide. Examples of nitrides that can be used include aluminum nitride and titanium nitride. Examples of fluorides include calcium fluoride. Examples of carbides include silicon carbide, titanium carbide, and tungsten carbide. Ceramic materials such as hydroxyapatite can also be used. Examples of organic materials include acrylic synthetic resins. Furthermore, any form that can be dispersed in water, such as powder or fiber, can be used. Therefore, carbon materials such as carbon nanofibers, carbon nanotubes, and graphene can be used if they are made dispersible in water using surface treatment, sizing agents, dispersants, etc. Furthermore, materials with catalytic, adsorbent, antibacterial, or other functional properties can be used to impart functionality to the fiber paper, making them a preferred embodiment.

The micro-sized material of the present invention can be contained in the fiber paper of the present invention at 50% by mass or more. Although there are certain limitations depending on the average particle size and surface potential of the micro-sized material, a content of up to 90% by mass is possible. However, as mentioned above, if the content exceeds 80% by mass, in the case of a micro-sized material with a small average particle size, such as 10 nm, the specific surface area tends to increase, and the aggregation state of the aggregates containing the micro-sized material tends to become non-uniform. Furthermore, in the case of a micro-sized material with a high surface potential, even if the average particle size is relatively large, such as several hundred nanometers, the aggregation state of the aggregates containing the micro-sized material tends to become non-uniform. Considering the aggregation state of these aggregates, the content of the micro-sized material in the fiber paper of the present invention is preferably in the range of 50% by mass or more and 80% by mass or less.

Materials other than the micro-sized material that can be used in the fiber paper of the present invention can be fiber materials that can be used in a wet papermaking process. Fiber materials that can be used in this wet papermaking process include all inorganic and organic fibers. These inorganic and organic fibers can be used in combination, or either can be used alone, depending on the performance to be imparted to the fiber paper of the present invention. When inorganic and organic fibers are used in combination, the inorganic and organic fibers can be mixed and used in any ratio. The content of the above fiber materials in the fiber paper of the present invention is preferably 5% by mass or more in total, and more preferably 10% by mass or more in total, taking into account the wet sheet strength and dry sheet physical properties of the fiber paper.

The inorganic fibers described in paragraph "0017" above can be selected as needed from fibers commonly used in wet papermaking processes, such as glass fiber, carbon fiber, rock wool, sepiolite, basalt, and alumina. The inorganic fibers can have a fiber diameter of 6 to 18 μm and a fiber length of 3 to 25 mm. Furthermore, short fibers, long fibers, and wool-like fibers can also be used. The glass fibers in the inorganic fibers can be any glass fiber that is resistant to breakage and capable of forming a fiber sheet. The glass fibers can have any glass composition, such as E-glass, A-glass, C-glass, or ARG-glass. The carbon fibers in the inorganic fibers can be polyacrylonitrile (PAN)-based carbon fibers or pitch-based fibers. Furthermore, biosoluble inorganic fibers, such as alkaline earth silicate wool and artificial vitreous (silicate) fibers, are preferably used to reduce the risk of hazards to the human body. Furthermore, the inorganic fibers can be mixed and used in any ratio.

As the organic fibers described in paragraph "0017," synthetic fibers such as polyethylene fibers, polypropylene fibers, polyester fibers, acrylic fibers, vinyl chloride fibers, and aramid fibers, as well as natural fibers such as wood pulp and cotton, can be used. Recycled pulp recycled from waste paper can also be used. Fibers that can be mixed with inorganic fibers and made into paper by a wet papermaking method are particularly preferred. Natural fibers such as wood pulp and cotton can also be used after being beaten to improve the physical strength of the paper layer of the fiber paper. The above organic fibers can also be mixed and used in any ratio.

Materials other than the micro-sized filler that can be used in the fiber paper of the present invention include filler materials that can be used in wet papermaking processes. Filler materials that can be used in this wet papermaking process include all fillers commonly used in wet papermaking processes. For example, inorganic fillers such as clay, heavy calcium carbonate, and talc, as well as organic fillers such as particulate synthetic resins, can be used. Regarding the shape, fillers in powder, fibrous, plate-like, spherical, and needle-like shapes can be used. The fillers can also be mixed in any ratio. The content of the filler material in the fiber paper of the present invention is the amount required to complement or improve the clogging, flame retardancy, adsorption, catalytic function, and other performance properties of the fiber paper, so it is preferably in the range of 0% to 30% by mass. From the viewpoint of maximizing the content of the micro-sized filler, a more preferred range is 10% to 25% by mass.

The filler material described in paragraph "0021" above can be a filler material with particularly high performance in terms of clogging, flame retardancy, adsorption, and catalytic function. Filler materials that achieve high clogging include those that are effective even with small amounts of spindle-shaped, scaly, or flat fillers, such as precipitated calcium carbonate, kaolin clay, and mica. Filler materials with adsorption capabilities include those that adsorb harmful gases such as volatile organic compounds (VOCs) and solvents, as well as moisture, and adsorbents such as activated carbon, zeolite, and silica gel. Flame retardants that impart flame retardancy or non-combustibility to fiber paper and fiber paper processed products include phosphate-based flame retardants such as ammonium polyphosphate and melamine phosphate, and guanidine-based flame retardants such as guanidine sulfamate. Filler materials with catalytic function can be used that decompose volatile organic compounds (VOCs) and solvents for purposes such as deodorization. For example, titanium oxide, iron-based catalysts, manganese-based catalysts, and noble metal-based catalysts can be mentioned.

Regarding materials other than the micro-sized material that can be used in the fiber paper of the present invention, we will now discuss binders that can be used in the wet papermaking process. In addition to the filler described above, it is preferable to contain a binder to bind the various components of the fiber paper. The binder can be a synthetic resin or natural binder commonly used in the wet papermaking process, such as polyvinyl alcohol resin, vinyl acetate resin, acrylic resin, epoxy resin, or urethane resin, or a natural binder such as starch. Binders can be used in solid form, such as powder or fiber, or in liquid form, such as an aqueous solution, dispersion, or emulsion. However, since they must be used in combination with a flocculating binder, solid forms such as powder or fiber are preferred. In particular, polyvinyl alcohol resin fibrous binders are particularly preferred to improve the physical properties of both wet and dry sheets of the fiber paper. If necessary, these binders can also be mixed in any amount. The content of the binder material in the fiber paper of the present invention is preferably in the range of 2% by mass to 10% by mass, more preferably in the range of 5% by mass to 8% by mass, taking into consideration the wet sheet strength retention and dry sheet physical properties of the fiber paper in wet papermaking production.

The cohesive binder used in the fiber paper of the present invention will be described. The cohesive binder of the present invention has properties that allow it to better cohere and fix fiber paper materials dispersed in water than ordinary binders when used in wet papermaking processes. This cohesive binder is usually of the same potential as the micro-sized materials and other materials dispersed in water. (In this case, the fixing agent is of the opposite potential to the cohesive binder in order to uniformly cohere and fix the cohesive binder to the micro-sized materials and other materials.)

The flocculating binder used in the present invention can be a synthetic resin or natural binder. Examples include synthetic resins such as polyvinyl alcohol resin, vinyl acetate resin, acrylic resin, epoxy resin, urethane resin, styrene-butadiene rubber resin, and nitrile-butadiene rubber resin, as well as natural polymers such as starch. Furthermore, because uniform dispersion and solubility in water are required, liquid forms such as aqueous solutions, emulsions, and dispersions are preferred. Among these forms, emulsions are more preferred from the viewpoints of water dispersibility, flocculation and fixation with a fixing agent for micro-sized materials and materials other than micro-sized materials, and ease of potential adjustment. Acrylic resin emulsions are most preferred because the composition of the synthetic resin polymer can be easily changed inexpensively and a variety of fiber paper sheet physical properties can be easily achieved. The content of the flocculating binder in the fiber paper of the present invention is preferably in the range of 1% to 15% by mass, more preferably 3% to 10% by mass, to improve the flocculation and particle size of the aggregates in the present invention and to consider the dry sheet physical properties of the fiber paper.

The colloidal particles of the present invention have an average particle size ranging from 5 nm to 1000 nm in order to aggregate the micro-sized materials and materials other than the micro-sized materials dispersed in water to an appropriate size. The colloidal particles can be made of either inorganic or organic materials as long as they have an aggregating effect. Examples of inorganic materials include metal oxides such as alumina and silica, while examples of organic materials include polymeric materials. The colloidal particles can be shaped like feathers, granules, or nano-granules, as in the case of alumina, or like spheres, chains, or pearl necklaces, as in the case of silica. The surface potential can be positively or negatively charged depending on the potential of the micro-sized materials and materials other than the micro-sized materials.

Furthermore, with regard to the colloidal particles of the present invention, feathery alumina particles are preferred from the viewpoint of increasing the size of aggregates of micro-sized materials dispersed in water and materials other than the micro-sized materials. Furthermore, since many micro-sized materials used in wetlay papermaking have a negative charge, positively charged colloidal particles are advantageous. In particular, alumina hydrate is preferred as a positively charged material, and feathery alumina hydrate particles with a positive charge are the most preferred colloidal particles. By aggregating and fixing these alumina hydrate feathery colloidal particles, the aggregates become larger than those obtained by aggregating and fixing micro-sized materials dispersed in water and materials other than the micro-sized materials with cation ions such as aluminum ions. Therefore, aggregates with an average particle size ranging from 1 μm to 10 μm, which are suitable for the formation and growth of paper layers in wetlay papermaking, can be formed and grown.

The content of the colloidal particles in the fiber paper of the present invention is preferably in the range of 0.1% by mass to 5% by mass, more preferably in the range of 1.0% by mass to 3% by mass, in order to maintain a good aggregation state of the aggregates in the present invention and to achieve a predetermined average particle diameter.

Furthermore, in order to impart various properties to the fiber paper of the present invention, auxiliary agents such as water repellents, wettability improvers, dyes, pigments, etc. may be used separately. Any auxiliary agent that is normally used in wet papermaking methods can be used.

When the fiber paper of the present invention is produced by a wet papermaking process, other flocculants and fixing agents may be used in addition to the colloidal particles of the present invention for the micro-sized materials dispersed in water and materials other than the micro-sized materials, as long as they do not interfere with the flocculation and fixation of the colloidal particles of the present invention. For example, aluminum sulfate, polyaluminum chloride (PAC), synthetic resins (polyamide epoxy resin, polyamine resin, acrylamide-acrylic ester resin, etc.), etc., can be used as long as they do not interfere with the flocculation and fixation of the colloidal particles of the present invention. These flocculants and fixing agents can be used alone or in combination of two or more.

The fiber paper of the present invention is produced by a wet papermaking method, and the paper machine used to produce the fiber paper is not particularly limited as long as it is a general paper machine, and any paper machine known in the papermaking industry can be used as appropriate, such as a Fourdrinier machine, a twin-wire machine, a hybrid machine, a cylinder machine, a Yankee machine, or various combination paper machines. However, a cylinder machine or a combination machine combining a short wire and a cylinder machine has a low dewatering pressure during paper layer formation and is therefore suitable for producing the fiber paper of the present invention.

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In the following examples and comparative examples, the mass % and basis weight are all based on the dry mass, and the mass % indicates the mass ratio to the total dry mass of the fiber paper.

60% by weight of silica gel with an average particle size of 2000 nm was uniformly dispersed in water with a total of 30% by weight of recycled pulp, mechanical pulp, polyester fiber, and vinylon fiber as organic fibers. 9% by weight of acrylic resin emulsion was added as an aggregating binder, and 1.0% by weight of nanoparticle-shaped colloidal alumina (Nissan Chemical Co., Ltd. Aluminasol #520-A) was added as a fixing agent to generate and fix the aggregates. The generated and grown aggregates were then processed using a wet papermaking method to obtain inorganic fiber paper. The target basis weight was 120.0 g/ ^m² .

60% by weight of silica gel with an average particle size of 2000 nm was uniformly dispersed in water with a total of 30% by weight of recycled pulp, mechanical pulp, polyester fiber, and vinylon fiber as organic fibers. 9% by weight of acrylic resin emulsion was added as an aggregating binder, and 1.0% by weight of feather-shaped colloidal alumina (Nissan Chemical Co., Ltd. Aluminasol #200) was added as a fixing agent to generate and fix the aggregates. The generated aggregates were then processed using a wet papermaking method to obtain inorganic fiber paper. The target basis weight was 120.0 g/ ^m² .

65% by weight of nano-zeolite with an average particle size of 100 nm was uniformly dispersed in water with 25% by weight of organic fibers (recycled pulp, polyethylene fiber, polyester fiber, and vinylon fiber) and 5% by weight of inorganic fiber (glass fiber). 4% by weight of acrylic resin emulsion was added as an aggregating binder, and 1.0% by weight of colloidal alumina (Nissan Chemical Co., Ltd., Aluminasol #200) was added as a fixing agent to form and fix the aggregates. The formed and grown aggregates were then processed using a wet papermaking method to obtain inorganic fiber paper. The target basis weight was 100.0 g/ ^m² .

Comparative Example 1

65% by weight of silica gel with an average particle size of 2000 nm was uniformly dispersed in water with 25% by weight of organic fibers (recycled pulp, mechanical pulp, polyester fiber, and vinylon fiber). 9% by weight of acrylic resin emulsion was added as a binder, and 1.0% by weight of aluminum ions (aluminum polysulfate) was added as a fixing agent to form aggregates. The resulting slurry was then processed using a wet papermaking method to obtain inorganic fiber paper with a target basis weight of 120.0 g/ ^m² .

Comparative Example 2

70% by weight of nano-zeolite with an average particle size of 100 nm was uniformly dispersed in water with 20% by weight of organic fibers (recycled pulp, polyethylene fiber, polyester fiber, and vinylon fiber) and 5% by weight of inorganic fiber (glass fiber). 4% by weight of acrylic resin emulsion was added as a binder, and 1.0% by weight of aluminum ions (polyaluminum sulfate) was added as a fixing agent to aggregate and fix the mixture, generating and growing aggregates. The generated aggregates were then processed using a wet papermaking method to obtain inorganic fiber paper. The target basis weight was 100.0 g/ ^m² .

The yields in the examples and comparative examples were evaluated by the following test method.
<Yield evaluation>
When the fiber papers of the above Examples and Comparative Examples were produced by a wet papermaking method, the aggregate mass required to produce fiber papers of a target basis weight was measured. Furthermore, the aggregate mass obtained from the solid mass of the fiber paper of the target basis weight was calculated (the aggregate mass when the theoretical yield was 100%). The yield was calculated as a percentage by dividing the aggregate mass required to produce fiber paper of the target basis weight by the aggregate mass obtained from the solid mass of the fiber paper of the target basis weight.

Possible industrial applications

The present invention makes it possible to produce fiber paper containing a high composition ratio of micro-sized materials using conventional wet papermaking methods with aggregates without requiring special equipment, and provides fiber paper containing a high composition ratio of micro-sized materials with various functions and a method for producing the same, which has a significant effect on adsorption performance and flame retardancy, particularly when used for adsorption or building material purposes.

Claims (4)

A method for producing fiber paper by a wet papermaking method, wherein the fiber paper contains micro-sized materials having an average particle diameter in the range of 1 nm to 9000 nm in an amount of 50% by mass to 80% by mass based on the dry mass of the entire fiber paper, and the method comprises the steps of: a first step of preparing a liquid by dispersing the micro-sized materials and materials other than the micro-sized materials in water; a second step of adding to the liquid an amount of an aggregation binder and colloidal particles having an average particle diameter in the range of 5 nm to 1000 nm in an amount of 0.1% by mass to 5% by mass based on the dry mass of the entire fiber paper, and aggregating and fixing the micro-sized materials, materials other than the micro-sized materials, the aggregation binder, and the colloidal particles in the liquid to form aggregates having an average particle diameter in the range of 20 μm to 500 μm, thereby forming a liquid containing the aggregates; and a third step of wet papermaking the liquid obtained in the second step. 2. The method for producing fiber paper according to claim 1 , wherein the fine-sized material is zeolite having an average particle size in the range of 50 nm to 200 nm. 3. The method for producing fiber paper according to claim 1 , wherein the colloidal particles are inorganic particles having an average particle diameter in the range of 5 nm to 1000 nm. 4. The method for producing fiber paper according to claim 1 , wherein the colloidal particles are alumina hydrate particles having an average particle diameter in the range of 5 nm to 1000 nm and a feather shape.