JP2018090678A - Flame-retardant material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant material containing an inorganic particle and a fiber.SOLUTION: According to the invention, inorganic particles having flame-retardant properties and a fiber are combined with each other to obtain a flame-retardant material. Sheets comprising a complex of inorganic particles and a fiber can be laminated to obtain a flame-retardant material having markedly excellent flame retardancy.SELECTED DRAWING: Figure 6D

Description

  The present invention relates to a flame retardant material using a composite of flame retardant inorganic particles and fibers.

  Fibers exhibit various properties based on functional groups on the surface, etc., but depending on the application, the surface may need to be modified. So far, techniques for surface modification of fibers have been developed. Yes.

  For example, regarding a technique for depositing inorganic particles on fibers such as cellulose fibers, Patent Document 1 describes a composite in which crystalline calcium carbonate is mechanically bonded onto fibers. 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 method. Patent Document 3 discloses a method for improving the whiteness and cleanliness of waste paper fibers by adding a large amount of filler to the fibers for paper and paperboard, and sending the slurry of waste paper pulp to a gas-liquid contact device. On the other hand, a technique is described in which an alkali salt slurry is contacted in the direction of flow with pulp in the contact zone, and a suitable reactive gas is fed and mixed with the sedimentary filler to adhere the filler to the fiber surface.

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

Japanese Patent Laid-Open No. 06-158585 US Pat. No. 5,679,220 US Pat. No. 5,665,205 Special table 2013-521417 gazette US Patent Publication No. 2011/000633

  An object of the present invention is to provide a flame retardant material using a composite of inorganic particles and fibers.

The inventors of the present invention have succeeded in developing an excellent flame retardant material by using a composite of flame retardant inorganic particles and fibers, and have completed the present invention.
The present invention includes, but is not limited to, the following inventions.
(1) A flame retardant comprising a composite of flame retardant inorganic particles and fibers.
(2) The flame retardant according to (1), wherein the fiber is a cellulose fiber.
(3) The flame retardant material according to (1) or (2), wherein the flame retardant inorganic particles are selected from the group consisting of magnesium carbonate, barium sulfate, aluminum hydroxide, and hydrotalcite.
(4) The flame retardant according to any one of (1) to (3), which is in the form of a sheet.
(5) The flame retardant according to any one of (1) to (4), wherein a composite sheet of flame retardant inorganic particles and fibers is laminated.
(6) The flame retardant material according to any one of (1) to (5), wherein a composite sheet of flame retardant inorganic particles and fibers is bonded to a substrate.
(7) The flame retardant according to any one of (1) to (6), wherein the average primary particle diameter of the flame retardant inorganic particles is 1.5 μm or less.
(8) The flame retardant material according to any one of (1) to (7), wherein the weight ratio of the flame retardant inorganic particles and the fibers is 5/95 to 95/5.

ADVANTAGE OF THE INVENTION According to this invention, a flame-retardant material can be provided using the fiber by which the surface was coat | covered with the flame-retardant inorganic particle.
In the present invention, when a composite of inorganic particles and fibers is used, such a composite has characteristics of both fibers and inorganic particles, and according to the present invention, it has excellent flame retardancy. It becomes possible to obtain a flame-retardant material. In addition, since a composite in which inorganic particles are attached to fibers is used, the production of a flame retardant is easy, and the yield (ash yield) of the inorganic particles is also good.

FIG. 1 is a schematic diagram of a reaction apparatus used for the synthesis of sample 1 (P: pump). FIG. 2 is a schematic diagram of the reaction apparatus used for the synthesis of sample 2 (P: pump). FIG. 3 is a schematic diagram of the test apparatus. FIG. 4 is an appearance photograph of the sample after the combustion test (from the upper left, pulp sheet, sheet 1, sheet 2, from the lower left, sheet 3, sheet 4). FIG. 5 is a schematic diagram of the reaction apparatus used for the synthesis of Sample 3-3 (left figure, P: pump). The right side of FIG. 5 is an enlarged schematic view of the ultra fine bubble generating part. FIG. 6A is an appearance photograph of Sample A after the combustion test (left: combustion surface, right: back surface). FIG. 6B is an appearance photograph of Sample B after the combustion test (left: combustion surface, right: back surface). FIG. 6C is an appearance photograph of Sample C after the combustion test (left: enlarged combustion surface, right: combustion surface). FIG. 6D is an appearance photograph of Sample D after the combustion test (left: combustion surface, right: back surface). FIG. 6E is an appearance photograph of Sample E after the combustion test (left: combustion surface, right: back surface). FIG. 6F is a photograph of the appearance of Sample F after the combustion test (left: combustion surface, right: back surface). FIG. 6G is an appearance photograph of sample G after the combustion test (left: combustion surface, right: back surface). FIG. 6H is a photograph of the appearance of Sample H after the combustion test. FIG. 6I is an appearance photograph of Sample I after the combustion test (left: combustion surface, right: back surface). FIG. 6J is an appearance photograph of Sample J after the combustion test (left: combustion surface, right: back surface).

The present invention relates to a flame retardant material using a composite of inorganic particles and fibers.
Fibers In the present invention, fibers such as cellulose fibers and aramid fibers and inorganic particles are composited. The fibers constituting the composite are preferably cellulose fibers. For example, 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 cellulose fiber raw materials include pulp fibers (wood pulp and non-wood pulp), cellulose nanofibers, bacterial cellulose, animal-derived cellulose such as sea squirts, and algae. Wood pulp is produced by pulping wood raw materials. That's fine. Wood materials include red pine, black pine, todomatsu, spruce, beech pine, larch, fir, tsuga, cedar, hinoki, larch, syrup, spruce, hiba, douglas fir, hemlock, white fur, spruce, balsam fur, cedar, pine, Coniferous trees such as Merck pine, Radiata pine, and mixed materials thereof, beech, hippopotamus, alder tree, oak, tab, shii, birch, broadleaf tree, poplar, tamo, dry willow, eucalyptus, mangrove, lawan, acacia, etc. Examples are materials.

  The method for pulping natural materials such as wood raw materials (woody raw materials) is not particularly limited, and examples thereof include pulping methods generally used in the paper industry. Wood pulp can be classified by pulping method, for example, chemical pulp digested by kraft method, sulfite method, soda method, polysulfide method, etc .; mechanical pulp obtained by pulping by mechanical force such as refiner, grinder; Semi-chemical pulp obtained by carrying out pulping by mechanical force after pretreatment by; waste paper pulp; deinked pulp and the like. Wood pulp may be unbleached (before bleaching) or bleached (after bleaching).

  Examples of the non-wood-derived pulp include cotton, hemp, sisal hemp, manila hemp, flax, straw, bamboo, bagasse, kenaf, sugar cane, corn, rice straw, straw, honey and so on.

  The pulp fiber may be either unbeaten or beaten, and may be selected according to the physical properties of the composite sheet, but it is preferable to beaten. Thereby, improvement of sheet strength and promotion of fixing of inorganic particles can be expected.

  A composite fiber of a synthetic fiber and a cellulose fiber can also be used in the present invention. For example, a composite fiber of a polyester fiber, a polyamide, a polyolefin, an acrylic fiber, a glass fiber, a carbon fiber, various metal fibers, etc. and a cellulose fiber is also used. be able to.

  Further, these cellulose raw materials are further processed to give powdery cellulose, chemically modified cellulose such as oxidized cellulose, and cellulose nanofiber: CNF (microfibrillated cellulose: MFC, TEMPO oxidized CNF, phosphate esterified CNF, carboxymethylated). CNF, machine pulverized CNF, etc.) can also be used. As the powdered cellulose used in the present invention, for example, a fixed particle size in the form of a rod shaft produced by a method of purifying and drying an undegraded residue obtained after acid hydrolysis of a selected pulp, pulverizing and sieving. A crystalline cellulose powder having a distribution may be used, or commercially available products such as KC Flock (manufactured by Nippon Paper Industries), Theolas (manufactured by Asahi Kasei Chemicals), and Avicel (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 size by a laser diffraction type particle size distribution analyzer. Is preferably 1 μm or more and 100 μm or less. The oxidized cellulose used in the present invention can be obtained, for example, by oxidizing in water using an oxidizing agent in the presence of a compound selected from the group consisting of N-oxyl compounds and bromides, iodides or mixtures thereof. it can. As the cellulose nanofiber, a method of defibrating the cellulose raw material is used. As the defibrating 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 single or multi-screw kneader, a bead mill, or the like. A method of defibration can be used. Cellulose nanofibers may be produced by combining one or more of the above methods. The fiber diameter of the produced cellulose nanofiber can be confirmed by observation with an electron microscope, and is, for example, in the range of 5 nm to 1000 nm, preferably 5 nm to 500 nm, more preferably 5 nm to 300 nm. When producing the cellulose nanofiber, before and / or after the cellulose is defibrated and / or refined, an arbitrary compound may be further added and reacted with the cellulose nanofiber to modify the hydroxyl group. it can. As functional groups to be modified, 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, azo group , Aryl group, aralkyl group, amino group, amide group, imide group, acryloyl group, methacryloyl group, propionyl group, propioyl group, butyryl group, 2-butyryl group, pentanoyl group, hexanoyl group, heptanoyl group, octanoyl group, nonanoyl group , Decanoyl group, undecanoyl group, dodecanoyl group, myristoyl group, palmitoyl group, stearoyl group, pivaloyl group, benzoyl group, naphthoyl group, nicotinoyl group, isonicotinoyl group, furoyl group, cinnamoyl group and other acyl groups, 2-methacryloyl Isocyanate groups such as oxyethylisocyanoyl 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 group, undecyl group, dodecyl group, myristyl group, palmityl group, stearyl group and other alkyl groups, oxirane group, oxetane group, oxyl group, thiirane group, thietane group and the like. 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 be an unsaturated bond. The compound used for introducing these functional groups is not particularly limited. 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, or a sulfonic acid-derived compound And the like, compounds having an alkyl group, compounds having an amine-derived group, and the like. Although it does not specifically limit as a compound which has a phosphoric acid group, Lithium dihydrogen phosphate which is phosphoric acid and the lithium salt of phosphoric acid, Dilithium hydrogen phosphate, Trilithium phosphate, Lithium pyrophosphate, Lithium polyphosphate is mentioned. . Furthermore, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate and sodium polyphosphate which are sodium salts of phosphoric acid are mentioned. Furthermore, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate which are potassium salts of phosphoric acid are mentioned. Further, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate which are ammonium salts of phosphoric acid are included. Of these, phosphoric acid, sodium phosphate, phosphoric acid potassium salt, and phosphoric acid ammonium salt are preferred from the viewpoint of high efficiency in introducing a phosphate group and easy industrial application. Sodium dihydrogen phosphate Although disodium hydrogen phosphate is more preferable, 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, but examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. It is done. Although it does not specifically limit as a derivative of the compound which has a carboxyl group, The derivative of the acid anhydride of the compound which has a carboxyl group and the acid anhydride imidation of a compound which has a carboxyl group are mentioned. Although it does not specifically limit as an acid anhydride imidation thing of a compound which has a carboxyl group, Imidation thing of dicarboxylic acid compounds, such as maleimide, succinic acid imide, and phthalic acid imide, is mentioned. The acid anhydride derivative of the compound having a carboxyl group is not particularly limited. For example, at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxyl group, such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride, etc. are substituted (for example, alkyl group, phenyl group, etc. ) Are substituted. Among the compounds having a group derived from a carboxylic acid, maleic anhydride, succinic anhydride, and phthalic anhydride are preferred because they are easily applied industrially and easily gasified, but are not particularly limited. Further, the cellulose nanofiber may be modified in such a manner that the compound to be modified is physically adsorbed on the cellulose nanofiber without being chemically bonded. Examples of the physically adsorbing compound include surfactants, and any of anionic, cationic, and nonionic may be used. When the above-described modification is performed before cellulose is defibrated and / or pulverized, these functional groups can be removed after defibrating and / or pulverization to return to the original hydroxyl group. By performing the modification as described above, it is possible to promote the defibration of the cellulose nanofiber or to easily mix it with various substances when the cellulose nanofiber is used.

  The fibers shown above may be used alone or in combination. Especially, it is preferable that wood pulp is included or the combination of wood pulp, non-wood pulp, and / or synthetic fiber is included, and it is more preferable that it is only wood pulp.

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

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

  The fiber length of the fibers to be combined is not particularly limited. For example, the average fiber length may be about 0.1 μm to 15 mm, and may be 1 μm to 12 mm, 100 μm to 10 mm, 500 μm to 8 mm, and the like.

  The fiber to be combined is preferably used in such an amount that 15% or more of the fiber surface is coated with inorganic particles. For example, the weight ratio of the fiber to the inorganic particles is 5/95 to 95/5. 10/90 to 90/10, 20/80 to 80/20, 30/70 to 70/30, or 40/60 to 60/40.

  In the composite according to the present invention, 15% or more of the fiber surface is coated with flame retardant inorganic particles. When the surface of the cellulose fiber is coated with such an area ratio, the flame retardancy is increased. Features due to the surface are reduced.

Flame Retardant Inorganic Particles In the present invention, a flame retardant material is obtained using a composite of flame retardant inorganic particles and fibers. Examples of the flame retardant inorganic particles include magnesium carbonate, aluminum hydroxide, barium sulfate, hydrotalcite, magnesium hydroxide, calcium carbonate, calcium phosphate, and silica, but magnesium carbonate, aluminum hydroxide, barium sulfate are particularly preferable. And hydrotalcite.

(Magnesium carbonate)
In a preferred embodiment, the present invention uses a composite of magnesium carbonate and fiber as a flame retardant material. The average particle diameter of the magnesium carbonate fine particles constituting the composite according to the present invention is preferably less than 50 μm, but may be magnesium carbonate having an average particle diameter of 30 μm or less. In a preferred embodiment, the average primary particle diameter of the magnesium carbonate fine particles can be about 10 nm to 3 μm.

  In addition, the magnesium carbonate obtained in the present invention may take the form of secondary particles in which fine primary particles are aggregated, and can generate secondary particles according to the application. You can also For grinding, ball mill, sand grinder mill, impact mill, high-pressure homogenizer, low-pressure homogenizer, dyno mill, ultrasonic mill, kanda grinder, attritor, stone mill, vibration mill, cutter mill, jet mill, breaker, beater Short shaft extruder, twin screw extruder, ultrasonic stirrer, household juicer mixer and the like.

  In the present invention, magnesium carbonate can be synthesized, for example, from a raw material selected from the group consisting of magnesium oxide, magnesite, dolomite, huntite, magnesium carbonate, magnesium hydroxide, brucite, and mixtures thereof. In a preferred embodiment, the magnesium carbonate of the present invention is synthesized from magnesium hydroxide.

  The composite according to the present invention may be prepared by synthesizing magnesium carbonate in a solution containing fibers, for example. At the time of obtaining magnesium hydroxide from a magnesium hydroxide precursor typified by magnesium oxide or the like, the fibers can be dispersed in the reaction solution. Further, the fiber can be dispersed in the step of obtaining magnesium carbonate from magnesium hydroxide. In any case, since the reaction solution is alkaline, the fibers can be swollen by being immersed in the reaction solution, and a composite of magnesium carbonate and fibers can be obtained efficiently. The carbonation reaction can be started immediately after the fibers are dispersed, or the carbonation reaction can be started after the fiber is further swollen by stirring for 15 minutes or more. For example, magnesium carbonate may be synthesized by injecting an aqueous suspension containing magnesium hydroxide into a reaction vessel. As will be described later, when jetting an aqueous suspension of magnesium hydroxide into the reaction vessel, it is a preferred embodiment to generate cavitation bubbles and synthesize magnesium carbonate in the presence thereof.

  In the present invention, the magnesium carbonate fine particles are synthesized in a solution containing fibers. The method for synthesizing magnesium carbonate can be performed by a known method. For example, magnesium bicarbonate can be synthesized from magnesium hydroxide and carbon dioxide, and basic magnesium carbonate can be synthesized from magnesium bicarbonate via normal magnesium carbonate. Magnesium carbonate can obtain magnesium bicarbonate, normal magnesium carbonate, basic magnesium carbonate, and the like by a synthesis method, but the magnesium carbonate according to the composite of the present invention is particularly preferably basic magnesium carbonate. This is because magnesium bicarbonate is relatively low in stability, and normal magnesium carbonate, which is a columnar (needle-like) crystal, may be difficult to fix to the fiber. On the other hand, by performing chemical reaction to basic magnesium carbonate in the presence of fibers, it is possible to obtain a composite of magnesium carbonate and fibers with the fiber surface coated in a scale shape.

  In a preferred embodiment of the present invention, 15% or more of the fiber surface is coated with magnesium carbonate. In a preferred embodiment, the composite of the present invention has a fiber coverage (area ratio) of 25% or more by magnesium carbonate, more preferably 40% or more, but according to the present invention, the coverage is 60% or more. It is also possible to produce more than 80% of the composite.

  When the magnesium carbonate and the fiber are complexed according to the present invention, the magnesium carbonate is not only easily mixed with the fiber compared with the case where the magnesium carbonate is mixed with the fiber, but also a product in which the magnesium carbonate is uniformly dispersed without agglomeration. Can be obtained. That is, according to the present invention, the yield of the composite of magnesium carbonate and fiber to the product (weight ratio of the magnesium carbonate that remains in the product) can be set to 60% or more, such as 70% or more and 90%. % Or more.

  In the present invention, it is preferable that cavitation bubbles exist when synthesizing magnesium carbonate. In this case, cavitation bubbles need not be present in all of the synthesis routes of magnesium carbonate, and cavitation bubbles may be present in at least one stage.

For example, when producing basic magnesium carbonate, magnesium oxide MgO is used as a magnesium source, and carbon dioxide gas CO ₂ is blown into magnesium hydroxide Mg (OH) ₂ obtained from magnesium oxide to produce magnesium bicarbonate Mg (HCO _{3 2} ) and basic magnesium carbonate is obtained from magnesium bicarbonate through normal magnesium carbonate MgCO ₃ .3H ₂ O. When the magnesium carbonate is synthesized, the basic magnesium carbonate can be synthesized on the fiber by allowing the fiber to be present. In a preferred embodiment, cavitation bubbles may be present when synthesizing magnesium carbonate. However, in the present invention, cavitation bubbles may be present in any synthesis step of magnesium carbonate. In a preferred embodiment, cavitation bubbles can be present in the step of synthesizing magnesium bicarbonate from magnesium hydroxide. In another embodiment, cavitation bubbles can be present in the step of synthesizing basic magnesium carbonate from magnesium bicarbonate or normal magnesium carbonate. In yet another embodiment, basic magnesium carbonate can be present when synthesized and then aged.

  Generally, a gas blowing type apparatus and a mechanical stirring type apparatus are known as reaction vessels for producing magnesium carbonate. In the gas blowing type, carbon dioxide gas is blown into the reaction vessel containing magnesium hydroxide to react, but it is difficult to control the size of the bubbles uniformly and finely by simply blowing carbon dioxide gas. There are limitations. On the other hand, in a mechanical stirring type apparatus, a stirrer is provided inside the apparatus, and carbon dioxide gas is introduced near the stirrer, whereby the carbon dioxide gas is made into fine bubbles and the reaction efficiency with carbon dioxide gas is improved.

  However, when stirring with a stirrer provided inside the reaction vessel as in the mechanical stirring type, if the concentration of the reaction solution is high or the carbonation reaction proceeds, the resistance of the reaction solution increases and it becomes difficult to sufficiently stir In some cases, it is difficult to accurately control the chemical reaction, and in order to perform sufficient stirring, a considerable load is applied to the stirrer, which is disadvantageous in terms of energy. In addition, when the gas inlet is at the bottom of the reaction vessel and the blades of the stirrer are installed near the bottom of the reaction vessel in order to improve the stirring, components with low solubility stay at the bottom and the gas injection port Block the balance of the stirrer. Furthermore, in the conventional method, in addition to the reaction tank, a stirrer and equipment for introducing carbon dioxide gas into the reaction tank are necessary, and the equipment is also expensive. And in the mechanical stirring type apparatus, although the reaction efficiency is improved by making the carbon dioxide gas supplied near the stirrer fine by the stirrer, the carbon dioxide gas cannot be sufficiently refined when the concentration of the reaction liquid is high, In terms of the carbonation reaction, it may be difficult to accurately control the form and the like of the generated inorganic particles. In the present invention, by synthesizing magnesium carbonate in the presence of cavitation bubbles, it is possible to efficiently promote the carbonation reaction and produce uniform magnesium carbonate fine particles on the fiber. In particular, by using jet cavitation, sufficient stirring can be performed without a mechanical stirrer such as a blade. In the present invention, a conventionally known reaction vessel can be used, and of course, the above-described gas blowing type or mechanical stirring type device can be used without any problem, and a nozzle or the like is used for these vessels. The jet cavitation may be combined.

  When synthesizing magnesium carbonate according to the present invention, the solid content concentration of the aqueous magnesium hydroxide suspension is preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight, still more preferably 1 to About 20% by weight. If the solid content concentration is low, the reaction efficiency is low and the production cost is high. If the solid content concentration is too high, the fluidity is deteriorated and the reaction efficiency is lowered. In the present invention, since magnesium carbonate is synthesized in the presence of cavitation bubbles, the reaction solution and carbon dioxide can be suitably mixed even when a suspension (slurry) having a high solid content concentration is used.

  As the aqueous suspension containing magnesium hydroxide, those commonly used can be used. For example, the aqueous suspension can be prepared by mixing magnesium hydroxide with water or by adding magnesium oxide to water. The conditions for preparing the magnesium hydroxide slurry from magnesium oxide are not particularly limited. For example, the MgO concentration is 0.1 wt% or more, preferably 1 wt% or more, and the temperature is 20 to 100 ° C., preferably 30 It is preferable to perform the treatment at -100 ° C for 5 minutes to 5 hours (preferably within 2 hours). The apparatus may be a batch type or a continuous type. In the present invention, the preparation of the magnesium hydroxide slurry and the carbonation reaction may be performed using separate apparatuses or in a single reaction tank.

(Barium sulfate)
In the present invention, when a composite of fiber such as cellulose fiber and barium sulfate is used, it can be synthesized by a known method. Barium sulfate is an ionic crystalline compound composed of barium ions and sulfate ions represented by BaSO ₄ , often in the form of a plate or a column, and is hardly soluble in water. 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. Although it can be obtained as a natural mineral, it can also be synthesized by chemical reaction. In particular, synthetic products by chemical reaction are used not only for pharmaceuticals (X-ray contrast media) but also widely used in paints, plastics, storage batteries, etc. by applying chemically stable properties.

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

(Aluminum hydroxide)
In a preferred embodiment, the present invention can use a composite of aluminum hydroxide and fiber as a flame retardant material. There are various methods for synthesizing aluminum hydroxide, which can be synthesized by adding an alkaline solution to a substance containing an aluminum salt. For example, it can be obtained by adding sodium hydroxide to aluminum sulfate. In addition, when aluminum sulfate is used as a raw material when synthesizing the barium sulfate, not only barium sulfate but also aluminum hydroxide can be synthesized simultaneously.

(Hydrotalcite)
In general, hydrotalcite is [M2 ⁺ _1- xM3 ⁺ _x (OH) ₂ ] [An ^- _{x /} n.mH2O] (wherein M2 ⁺ is a divalent metal ion and M3 ⁺ is trivalent. A ⁿ⁻ _{x / n} represents an interlayer anion, and 0 <x <1, where n is the valence of A, and 0 ≦ m <1. Here, M ²⁺ , which is a divalent metal ion, is a trivalent metal ion such as Mg ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca ²⁺ , Ba ²⁺ , Cu ²⁺ , Mn ^2+. there ^{M 3+} are, for ^{example, Al 3+, Fe 3+, Cr} 3+, Ga 3+ , etc., which ^{a n-} is an interlayer anion, for _{^{example, OH -, Cl -, CO}} 3 -, SO 4 - n-valent such as Anions can be mentioned, and x is generally in the range of 0.2 to 0.33. The crystal structure has a laminated structure composed of a two-dimensional basic layer in which octahedral brucite units having a positive charge are arranged and an intermediate layer having a negative charge.

  Hydrotalcite has been used for various applications utilizing its anion exchange function, such as ion exchange materials, adsorbents, deodorants and the like. In addition, by utilizing the combination of constituent metal ions, hydrotalcite in which each constituent metal ion is in a well-mixed state is heated and dehydrated, or further heated and fired to easily produce a complex oxide with a uniform composition. In some cases, it can be obtained for use as a catalyst.

  The proportion of hydrotalcite in the composite of the present invention can be 10% or more, can be 20% or more, and can be preferably 40% or more. The ash content of the composite of hydrotalcite and fiber can be measured according to JIS P 8251: 2003. In the present invention, the ash content of the composite of hydrotalcite and fiber can be 10% or more, can be 20% or more, and preferably 40% or more. Moreover, the composite of hydrotalcite and fiber of the present invention preferably contains 10% or more of magnesium or zinc in the ash, and more preferably contains 40% or more. The magnesium or zinc content in the ash can be quantified by fluorescent X-ray analysis.

  In a preferred embodiment of the present invention, 15% or more of the fiber surface is covered with hydrotalcite. In a preferred embodiment, the composite of the present invention has a fiber coverage (area ratio) of 25% or more by hydrotalcite, more preferably 40% or more, but according to the present invention, the coverage is 60% or more. It is also possible to produce a composite of 80% or more. In a preferred embodiment, the composite of hydrotalcite and fiber according to the present invention is not only fixed on the outer surface of the fiber and the inner side of the lumen, but also generated on the inner side of the microfibril. It is clear from the result of microscopic observation.

  When hydrotalcite and fiber are composited according to the present invention, hydrotalcite is not only easily mixed with the fiber compared with the case where hydrotalcite is mixed with fiber, but also uniformly dispersed without agglomeration. Product can be obtained. That is, according to the present invention, the yield of the composite of hydrotalcite and fibers to the product (weight ratio in which the added hydrotalcite remains in the product) can be 65% or more, and 70% or more. Or 85% or more.

In the present invention, a hydrotalcite / fiber composite can be produced by synthesizing hydrotalcite in a solution in the presence of fibers.
The synthesis method of hydrotalcite can be based on a known method. For example, the fibers are immersed in an aqueous carbonate solution containing carbonate ions constituting an intermediate layer and an alkaline solution (such as sodium hydroxide) in a reaction vessel, and then an acid solution (divalent metal ions and trivalent ions constituting a basic layer) Hydrotalcite is synthesized by adding a metal salt aqueous solution containing metal ions and controlling the temperature, pH, etc., and coprecipitation reaction. Further, in the reaction vessel, the fiber is immersed in an acid solution (metal salt aqueous solution containing divalent metal ions and trivalent metal ions constituting the basic layer), and then carbonate aqueous solution containing carbonate ions constituting the intermediate layer. Hydrotalcite can also be synthesized by dropwise addition of an alkaline solution (such as sodium hydroxide) and controlling the temperature, pH, etc. and coprecipitation reaction. Although the reaction at normal pressure is common, there is another method obtained by hydrothermal reaction using an autoclave or the like (Japanese Patent Laid-Open No. 60-6619).

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

  In the present invention, water is used for the preparation of the suspension. As this water, normal tap water, industrial water, ground water, well water, etc. can be used, ion-exchanged water, distilled water, Pure water, industrial waste water, and water obtained during the production process can be suitably used.

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

(Synthesis of complex)
In one preferred embodiment, the composite of the present invention can be obtained by synthesizing inorganic particles in the presence of fibers such as cellulose fibers. This is because the fiber surface is a suitable place for the precipitation of inorganic particles, so that a composite of fibers and inorganic particles can be easily synthesized.

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

  In addition, the inorganic particles in the composite of the present invention may take the form of secondary particles in which fine primary particles are aggregated, and secondary particles according to the application can be generated by an aging process, or by pulverization. Agglomerates can also be made fine. For grinding, ball mill, sand grinder mill, impact mill, high-pressure homogenizer, low-pressure homogenizer, dyno mill, ultrasonic mill, kanda grinder, attritor, stone mill, vibration mill, cutter mill, jet mill, breaker, beater Short shaft extruder, twin screw extruder, ultrasonic stirrer, household juicer mixer and the like.

  The composite obtained by the present invention can be used in various shapes, for example, powders, pellets, molds, aqueous suspensions, pastes, sheets, and other shapes. Moreover, it can also be set as molded objects, such as a mold, particle | grains, and a pellet, with a composite as a main component and other materials. There is no particular limitation on the dryer in the case of drying into a powder, but for example, an air dryer, a band dryer, a spray dryer or the like can be preferably used.

  The composite obtained by the present invention can be used for various applications by taking advantage of its flame retardant properties, for example, paper, fiber, cellulosic composite material, filter material, paint, plastic and other resins, rubber, Elastomer, ceramic, glass, tire, building material (asphalt, asbestos, cement, board, concrete, brick, tile, plywood, fiberboard, wall material, ceiling material, partition board, wallpaper, etc.), various carriers (catalyst carrier, pharmaceuticals) Carrier, agricultural chemical carrier, microbial carrier, etc.), adsorbent (impurity removal, deodorization, dehumidification, etc.), wrinkle prevention agent, clay, abrasive, modifier, repair material, heat insulating material, heat-resistant material, heat dissipation material, moisture-proof material Water repellent material, water resistant material, light shielding material, sealant, shielding material, insect repellent, adhesive, ink, cosmetics, medical material, paste material, anti-discoloration agent, food additive, Agent excipient, dispersant, shape retention agent, water retention agent, filter aid, essential oil material, oil treatment agent, oil modifier, radio wave absorber, insulation material, sound insulation material, vibration proof material, semiconductor sealing material, It can be widely used for radiation shielding materials, cosmetics, fertilizers, feeds, fragrances, paint / adhesive additives, sanitary products (disposable diapers, sanitary napkins, incontinence pads, breast milk pads, etc.). Moreover, it can be used for various fillers and coating agents in the above applications. Among these, it can be suitably used particularly for building materials (wall materials, ceiling materials, partition boards, wallpaper, etc.) from the viewpoint of excellent flame retardancy and material adsorption / desorption performance.

  Moreover, when using the composite_body | complex obtained by this invention, the particle | grains generally called an inorganic filler and an organic filler, and various fibers can be used together. For example, as 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) ), Talc, zinc oxide, zinc stearate, titanium dioxide, silica made from sodium silicate and mineral acid (white carbon, silica / calcium carbonate composite, silica / titanium dioxide composite), white clay, bentonite, diatomaceous earth, Examples thereof include calcium sulfate, zeolite, an inorganic filler that regenerates and uses the ash obtained from the deinking process, and an inorganic filler that forms a complex with silica or calcium carbonate in the process of regeneration. As the calcium carbonate-silica composite, amorphous silica such as white carbon may be used together with calcium carbonate and / or light calcium carbonate-silica composite. Organic fillers include urea-formalin resin, polystyrene resin, phenol resin, fine hollow particles, acrylamide composites, wood-derived materials (fine fibers, microfibril fibers, powder kenaf), modified insolubilized starch, ungelatinized starch, etc. Is mentioned. Fibers include natural fibers such as cellulose, synthetic fibers that are artificially synthesized from raw materials such as petroleum, regenerated fibers (semi-synthetic fibers) such as rayon and lyocell, and inorganic fibers. Can be used.

  The average particle diameter, shape, and the like of the inorganic particles constituting the composite of the present invention can be confirmed by observation with an electron microscope. Furthermore, inorganic particles having various sizes and shapes can be combined with fibers by adjusting the synthesis conditions of the inorganic particles.

  The manufacturing method of the composite based on this invention makes it essential to synthesize | combine an inorganic particle in the solution containing a fiber. In the following, synthesis of a composite of barium sulfate and fibers will be described as an example, but barium sulfate may be other inorganic particles. When a composite of barium sulfate and fiber is used, for example, when an alkaline barium sulfate precursor typified by barium hydroxide is used as a raw material, the fiber is dispersed in advance in a barium sulfate precursor solution. Therefore, a composite of inorganic particles and fibers can be obtained efficiently. The reaction can be started after promoting the swelling of the fibers by stirring them for 15 minutes or more after mixing, but the reaction may be started immediately after mixing. There are no particular restrictions on the form of the reaction tank and the stirring conditions for obtaining this composite. For example, a composite containing a fiber and a barium sulfate precursor is stirred and mixed in an open reaction tank to synthesize the composite. Alternatively, it may be synthesized by injecting an aqueous suspension containing fibers and a barium sulfate precursor into a reaction vessel. As will be described later, when an aqueous suspension of a barium sulfate precursor is injected into a reaction vessel, cavitation bubbles may be generated and barium sulfate may be synthesized in the presence of the bubbles.

  In the present invention, the liquid may be ejected under conditions that cause cavitation bubbles in the reaction vessel, or may be ejected under conditions that do not cause cavitation bubbles. The reaction vessel is preferably a pressure vessel in any case. In addition, the pressure vessel in this invention is a container which can apply the pressure of 0.005 Mpa or more. In the condition that does not generate cavitation bubbles, the pressure in the pressure vessel is preferably 0.005 MPa to 0.9 MPa in static pressure.

(Cavitation bubbles)
When the composite according to the present invention is synthesized, barium sulfate 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 referred to as a cavity phenomenon. Bubbles generated by cavitation (cavitation bubbles) are generated with very small “bubble nuclei” of 100 microns or less existing in the liquid as the nucleus 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 jetting fluid at high pressure, cavitation is generated by stirring at high speed in the fluid, cavitation is generated by causing explosion in the fluid, ultrasonic vibration It can be considered that cavitation is generated by a child (vibratory cavitation).

  In particular, in the present invention, since cavitation bubbles are easily generated and controlled, it is preferable to generate cavitation bubbles by ejecting a fluid at a high pressure. In this aspect, by compressing the jet liquid using a pump or the like and jetting it through a nozzle or the like at high speed, cavitation bubbles are generated at the same time as the liquid itself expands due to extremely high shearing force near the nozzle and sudden pressure reduction. . The method using a fluid jet has high generation efficiency of cavitation bubbles, and can generate cavitation bubbles having a stronger collapse impact force. In the present invention, controlled cavitation bubbles are present when synthesizing barium sulfate, which is clearly different from cavitation bubbles that cause uncontrollable harm that naturally occurs in fluid machinery.

  In the present invention, cavitation can be generated by using a reaction solution such as a raw material as an injection liquid as it is, or cavitation bubbles can be generated by injecting some fluid into the reaction vessel. The fluid in which the liquid jet forms a jet may be any liquid, gas, 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 can be added to the above fluid as a new fluid. The fluid and the new fluid may be uniformly mixed and ejected, but may be ejected separately.

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

Further, when the cavitation is generated by injecting the injection liquid through the nozzle or the orifice pipe, the pressure of the injection liquid (upstream pressure) is desirably 0.01 MPa or more and 30 MPa or less, and 0.7 MPa or more and 20 MPa or less. It is preferable that it is 2 MPa or more and 15 MPa or less. When the upstream pressure is less than 0.01 MPa, it is difficult to produce a pressure difference with the downstream pressure, and the effect is small. On the other hand, when the pressure is higher than 30 MPa, a special pump and a pressure vessel are required, and energy consumption increases, which is disadvantageous in terms of cost. On the other hand, the pressure in the container (downstream pressure) is preferably 0.005 MPa to 0.9 MPa in static pressure.
Moreover, the ratio of the pressure in the container and the pressure of the jet liquid is preferably in the range of 0.001 to 0.5.

  In the present invention, the inorganic particles can also be synthesized by spraying the spray liquid under conditions that do not generate cavitation bubbles. Specifically, it is more preferable that the pressure of the spray liquid (upstream pressure) is 2 MPa or less, preferably 1 MPa or less, and the pressure of the spray liquid (downstream pressure) is released to 0.05 MPa or less.

  The jet velocity of the jet liquid is desirably in the range of 1 m / second to 200 m / second, and preferably in the range of 20 m / second to 100 m / second. When the jet velocity is less than 1 m / sec, the effect is weak because the pressure drop is low and cavitation hardly occurs. On the other hand, when it is higher than 200 m / sec, a high pressure is required and a special device is required, which is disadvantageous in terms of cost.

  What is necessary is just to generate | occur | produce the cavitation generation | occurrence | production place in this invention in the reaction container which deposits an inorganic particle. Moreover, although it is possible to process by one pass, it can also circulate as many times as necessary. Furthermore, it can be processed in parallel or in permutation using a plurality of generating means.

  The liquid injection for generating cavitation may be performed in a container open to the atmosphere, but is preferably performed in a pressure container in order 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, and more preferably 20% by weight or less. This is because the cavitation bubbles easily act on the reaction system uniformly at such a concentration. In addition, the aqueous suspension of slaked lime that is the reaction solution preferably has a solid concentration of 0.1% by weight or more from the viewpoint of reaction efficiency.

  When synthesizing a complex in the present invention, the reaction can be controlled by monitoring the pH of the reaction solution as long as the pH of the reaction solution changes as the reaction proceeds.

  In the present invention, by increasing the jetting pressure of the liquid, the flow velocity of the jetting liquid is increased, and accordingly, the pressure is lowered, and stronger cavitation can be generated. Further, by pressurizing the pressure in the reaction vessel, the pressure in the region where the cavitation bubbles collapse is increased and the pressure difference between the bubbles and the surroundings increases, so that the bubbles collapse violently and the impact force can be increased. 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. In general, the impact force is considered to be the maximum at the midpoint between the melting point and the boiling point. Therefore, in the case of an aqueous solution, a temperature around 50 ° C. is suitable, but even below that temperature is affected by the vapor pressure. Therefore, a high effect can be obtained within the above range.

  In the present invention, the energy necessary for generating cavitation can be reduced by adding a surfactant. As the surfactant to be used, known or novel surfactants, for example, nonionic surfactants such as fatty acid salts, higher alkyl sulfates, alkylbenzene sulfonates, higher alcohols, alkylphenols, alkylene oxide adducts such as fatty acids, etc. , Anionic surfactants, cationic surfactants, amphoteric surfactants and the like. These may consist of a single component or a mixture of two or more components. The addition amount may be an amount necessary for reducing the surface tension of the jet liquid and / or the liquid to be jetted.

  In one embodiment of the present invention, a composite can be synthesized by synthesizing inorganic particles in a solution containing fibers, and a method for synthesizing inorganic particles can be based on a known method.

  In the present invention, water is used for the preparation of the suspension. As this water, normal tap water, industrial water, ground water, well water, etc. can be used, ion-exchanged water, distilled water, Pure water, industrial waste water, and water obtained when separating and dehydrating the reaction liquid can be suitably used.

  Moreover, in this invention, the reaction liquid of a reaction tank can be circulated and used. By circulating the reaction liquid in this way and promoting the stirring of the solution, it becomes easy to increase the reaction efficiency and obtain the desired complex.

  When producing the composite of the present invention, various known auxiliaries can be further added. For example, chelating agents 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, ethylenediaminetetra Aminopolycarboxylic acids such as acetic acid and their alkali metal salts, alkali metal salts of polyphosphoric acid such as hexametaphosphoric acid and tripolyphosphoric acid, amino acids such as glutamic acid and aspartic acid and their alkali metal salts, acetylacetone, methyl acetoacetate, acetoacetic acid Examples include ketones such as allyl, saccharides such as sucrose, and polyols such as sorbitol. In addition, as surface treatment agents, saturated fatty acids such as palmitic acid and stearic acid, unsaturated fatty acids such as oleic acid and linoleic acid, resin acids such as alicyclic carboxylic acid and abietic acid, salts, esters and ethers thereof, alcohols Activators, sorbitan fatty acid esters, amide or amine surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonyl phenyl ether, sodium alpha olefin sulfonate, long chain alkyl amino acids, amine oxides, alkyl amines, fourth A quaternary ammonium salt, aminocarboxylic acid, phosphonic acid, polyvalent carboxylic acid, condensed phosphoric acid and the like can be added. Moreover, a dispersing agent can also be used as needed. Examples of the dispersant include sodium polyacrylate, sucrose fatty acid ester, glycerin fatty acid ester, acrylic acid-maleic acid copolymer ammonium salt, methacrylic acid-naphthoxypolyethylene glycol acrylate copolymer, methacrylic acid-polyethylene glycol. Examples include monomethacrylate copolymer ammonium salts and polyethylene glycol monoacrylate. These can be used alone or in combination. The timing of addition may be before or after the synthesis reaction. Such an additive can be added in an amount of preferably 0.001 to 20%, more preferably 0.1 to 10% with respect to the inorganic particles.

  When synthesizing the complex in the present invention, the reaction conditions are not particularly limited, and can be appropriately set according to the application. For example, the temperature of the synthesis reaction can be 0 to 90 ° C, preferably 10 to 70 ° C. The reaction temperature can be controlled by a temperature controller, and if the temperature is low, the reaction efficiency decreases and the cost increases, whereas if it exceeds 90 ° C., coarse inorganic particles tend to increase.

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

  In addition, the reaction can be controlled by the electric conductivity of the reaction solution and the reaction time. Specifically, the time during which the reaction product stays in the reaction vessel can be adjusted and controlled. In addition, in this invention, reaction can also be controlled by stirring the reaction liquid of a reaction tank or making reaction multistage reaction.

  In the present invention, since the complex which is a reaction product is obtained as a suspension, it can be stored in a storage tank or subjected to processing such as concentration, dehydration, pulverization, classification, aging, and dispersion as necessary. Can do. These can be performed by known processes, and may be appropriately determined in consideration of the application and energy efficiency. For example, the concentration / dehydration treatment is performed using a centrifugal dehydrator, a sedimentation concentrator, or the like. Examples of the centrifugal dehydrator include a decanter and a screw decanter. When using a filter or a dehydrator, the type is not particularly limited and a general one can be used. For example, a pressure-type dehydrator such as a filter press, a drum filter, a belt press, a tube press, A calcium carbonate cake can be obtained by suitably using a vacuum drum dehydrator such as an Oliver filter. For grinding, ball mill, sand grinder mill, impact mill, high-pressure homogenizer, low-pressure homogenizer, dyno mill, ultrasonic mill, kanda grinder, attritor, stone mill, vibration mill, cutter mill, jet mill, breaker, beater Short shaft 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 vibrating screen, a heavy foreign matter cleaner, a lightweight foreign matter cleaner, a reverse cleaner, a sieving tester, and the like. Examples of the dispersion method include a high-speed disperser and a low-speed kneader.

  The composite obtained by the present invention can be blended in a filler or pigment in a suspension state without being completely dehydrated, but can also be dried to form a powder. Although there is no restriction | limiting in particular also about the dryer in this case, For example, an airflow dryer, a band dryer, a spray dryer etc. can be used conveniently.

  The composite obtained by the present invention can be modified by a known method. For example, in an embodiment, the surface can be hydrophobized to improve miscibility with a resin or the like.

Flame retardant material using composite In the present invention, the above-mentioned composite is used to form a flame retardant material. For example, when the composite obtained by the present invention is made into a sheet, a high ash content sheet can be easily produced, and this can be used as a flame retardant. Moreover, the obtained sheet | seat can be bonded together and a laminated body (multilayer sheet or multilayer board) can also be made into a flame-retardant material. Examples of the paper machine (paper machine) used for sheet production include a long paper machine, a round paper machine, a gap former, a hybrid former, a multilayer paper machine, and a known paper machine that combines the paper making methods of these devices. It is done. The press linear pressure in the paper machine and the calendar linear pressure in the case where the calendar process is performed later can be determined within a range that does not hinder the operability and the performance of the composite sheet. In addition, starch, various polymers, pigments, and mixtures thereof may be applied to the formed sheet by impregnation or coating.

  When forming into a sheet, a wet and / or dry paper strength agent (paper strength enhancer) can be added. Thereby, the intensity | strength of a composite sheet can be improved. Examples of paper strength agents include urea formaldehyde resin, melamine formaldehyde resin, polyamide, polyamine, epichlorohydrin resin, vegetable gum, latex, polyethyleneimine, glyoxal, gum, mannogalactan polyethyleneimine, polyacrylamide resin, polyvinylamine. And a resin such as polyvinyl alcohol; a composite polymer or copolymer composed of two or more selected from the above resins; starch and processed starch; carboxymethylcellulose, guar gum, urea resin, and the like. The addition amount of the paper strength agent is not particularly limited.

  Moreover, in order to promote the fixing of the filler to the fiber or to improve the yield of the filler or fiber, a high molecular weight polymer or an inorganic substance can be added. For example, polyethyleneimine and modified polyethyleneimines containing tertiary and / or quaternary ammonium groups, polyalkylenimines, dicyandiamide polymers, polyamines, polyamine / epichlorohydrin polymers, and dialkyldiallyl quaternary ammonium monomers, dialkyls as coagulants Cations such as aminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide and polymers of acrylamide and dialkylaminoalkyl methacrylamide, polymers of monoamines and epihalohydrin, polymers with polyvinylamine and vinylamine moieties, and mixtures thereof In addition to the functional polymer, a polymer obtained by copolymerizing an anionic group such as a carboxyl group or a sulfone group in the polymer molecule. Onritchi of zwitterionic polymer, and a mixture of cationic polymer and an anionic or zwitterionic polymers may be used. As a retention agent, a cationic, anionic, or amphoteric polyacrylamide-based material can be used. In addition to these, a retention system called a so-called dual polymer that uses at least one kind of cation or anionic polymer can also be applied, and at least one kind of anionic bentonite, colloidal silica, polysilicic acid, It is a multi-component yield system that uses inorganic fine particles such as polysilicic acid or polysilicate microgels and their modified aluminum products, or one or more organic fine particles having a particle size of 100 μm or less, called so-called micropolymers obtained by crosslinking polymerization of acrylamide. Also good. In particular, when the polyacrylamide material used alone or in combination has a weight average molecular weight of 2 million daltons or more by the intrinsic viscosity method, a good yield can be obtained, preferably 5 million daltons or more, more preferably Can obtain a very high yield in the case of the above-mentioned acrylamide-based material of 10 million daltons or more and less than 30 million daltons. The form of the polyacrylamide-based material may be an emulsion type or a solution type. The specific composition is not particularly limited as long as the substance contains an acrylamide monomer unit as a structural unit. For example, a copolymer of quaternary ammonium salt of acrylate ester and acrylamide, or acrylamide And a quaternized ammonium salt after copolymerization of acrylate and acrylate. The cationic charge density of the cationic polyacrylamide material is not particularly limited.

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

The basis weight of the sheet can be appropriately adjusted according to the purpose. However, when it is 40 to 1200 g / m ² , the flame retardancy is high, and the drying load during production is low, which is favorable. The basis weight of the sheet, also can be a 60~1000g / ^{m 2,} may be a 100 to 600 / ^{m 2.}

  It is also possible to use a molding method other than sheeting, for example, a method of pouring raw materials into a mold and drawing it by suction dehydration and drying as called a pulp mold, or spreading and drying on the surface of a molded product such as resin or metal Thereafter, molded articles having various shapes can be obtained by a method of peeling from the substrate. Further, it can be molded into a plastic like by mixing a resin, or it can be shaped like a ceramic by adding a mineral such as silica or alumina and firing. In the blending / drying / molding described above, only one type of composite can be used, or two or more types of composites can be mixed and used. When two or more types of composites are used, those obtained by mixing them in advance can be used, or those obtained by blending, drying and molding each can be mixed later. Moreover, when using a composite sheet | seat by laminating | stacking, for example, 2-20 sheets can be used, It is preferable to use 3-15 sheets, It is further using 4-10 sheets further preferable. Thus, by setting it as the laminated body (multilayer sheet and multilayer board) which piled up the composite sheet, a flame retardance is improved significantly. When laminating sheets, a binder or the like may be used as appropriate.

  Furthermore, the composite sheet can be bonded to one side or both sides of the base material to form a composite board having flame retardancy. The composite sheet to be bonded may be one sheet or plural sheets. However, in the case of bonding a plurality of composite sheets, for example, 2 to 20 sheets can be used, and 3 to 15 sheets can be used. It is preferable to use a sheet, and it is more preferable to use 4 to 10 sheets. The substrate is not particularly limited, but various plate materials such as wood, paper, and nonwoven fabric can be suitably used.

  Further, various organic substances such as polymers and various inorganic substances such as pigments may be added to the composite molded article later. For example, it is possible to laminate a desired substance on the surface by applying (applying) a sheet (including laminated ones and board-like ones). For example, a binder such as starch or PVA, a hydrophobizing agent such as a sizing agent, an organic or inorganic flame retardant, and the like can be applied. Furthermore, it is possible to further enhance the function by impregnating sheets (including laminated ones and board-like ones) with various substances.

  These sheets, laminates and boards can be further processed into a three-dimensional structure such as a honeycomb structure.

  Hereinafter, the present invention will be described in more detail with specific examples, but the present invention is not limited to such specific examples. Unless otherwise specified in the present specification, concentrations and parts are based on weight, and numerical ranges are described as including the end points.

Experiment 1: Production of composite sheet and evaluation of flame retardancy (1) Synthesis of composite The composite of magnesium carbonate and pulp fiber (samples 1-1 to 1-3) and hydrotalcite A composite of pulp fibers (Sample 2) was synthesized.

(Sample 1-1: Composite of magnesium carbonate and pulp fiber)
350 g of magnesium hydroxide (Ube Materials, UD653) and 350 g of kraft pulp (LBKP / NBKP = 1/1, CSF: 370 ml, average fiber length: 0.9 mm) were added to water to prepare an aqueous suspension.

As shown in FIG. 1, 35 L of this aqueous suspension is placed in a cavitation apparatus (45 L volume), and while circulating the reaction solution, carbon dioxide gas is blown into the reaction vessel and the magnesium carbonate fine particles and the fibers are separated by the carbon dioxide method. A complex was synthesized. The reaction start temperature was about 40 ° C., the carbon dioxide gas was supplied with a commercially available liquefied gas, and the amount of carbon dioxide blown was 20 L / min. When the pH of the reaction solution reached about 7.8, the introduction of CO ₂ was stopped (pH before the reaction was 10.3), and then the cavitation generation and the circulation of the slurry in the apparatus were continued for 30 minutes, A composite of magnesium carbonate fine particles and pulp fibers was obtained (Sample 1-1, average primary particle size of inorganic particles: 0.8 μm).

  In the synthesis of the complex, cavitation bubbles were generated in the reaction vessel by circulating the reaction solution and injecting it into the reaction vessel. 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, and the inlet pressure (upstream pressure) was The outlet pressure (downstream pressure) was 7 MPa and 0.3 MPa.

  With respect to the obtained composite, the weight ratio of fiber: inorganic particles was measured and found to be 50:50 (ash content: 50%). The weight ratio (ash content) was determined by suction-filtering the composite slurry (3 g in terms of solid content) using filter paper, then drying the residue in an oven (105 ° C., 2 hours), and burning the organic content at 525 ° C. It was calculated from the weight before and after combustion.

(Sample 1-2: Composite of magnesium carbonate and pulp fiber)
Except that the amount of magnesium hydroxide charged was 1200 g, the type of kraft pulp used was LBKP (CSF = 490 mL, average fiber length = 0.75 mm), the amount of pulp charged was 300 g, and the total amount of aqueous suspension was 30 L, A composite was synthesized in the same manner as Sample 1-1 (average primary particle size of inorganic particles: 0.8 μm). The ash content of the obtained composite was 70%.

(Sample 1-3: Composite of magnesium carbonate and pulp fiber)
A composite was synthesized in the same manner as in Sample 1-1 except that the inlet pressure of the apparatus during the reaction was 2 MPa and the outlet pressure was 0.2 MPa (average primary particle diameter of inorganic particles: 1 μm). The resulting composite had an ash content of 49%.

(Sample 2: Composite of hydrotalcite and pulp fiber)
In order to synthesize Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O as hydrotalcite (HT), Na ₂ CO ₃ (Wako Pure Chemicals) and NaOH (Wako Pure Chemicals) are used as alkaline solutions (A solutions). As a mixed aqueous solution and an acid solution (B solution), a mixed aqueous solution of MgCl ₂ (Wako Pure Chemical Industries) and AlCl ₃ (Wako Pure Chemical Industries) was prepared.
・ Alkaline solution (A solution, Na ₂ CO ₃ concentration: 0.05M, NaOH concentration: 0.8M)
Acid solution (B solution, Mg-based, MgCl ₂ concentration: 0.3M, AlCl ₃ concentration: 0.1M)
Cellulose fibers were used as the fibers to be combined. Specifically, it contains hardwood bleached kraft pulp (LBKP, manufactured by Nippon Paper Industries) and softwood bleached kraft pulp (NBKP, manufactured by Nippon Paper Industries) at a weight ratio of 8: 2, and is a Canadian standard drainage using a single disc refiner (SDR). Pulp fibers whose degree was adjusted to 390 ml were used (average fiber length 0.8 mm).

  Pulp fibers were added to the alkaline solution to prepare an aqueous suspension containing pulp fibers (pulp fiber concentration: 1.56%, pH: about 12.4). This aqueous suspension (pulp solid content 30 g) is put into a 10 L reaction vessel, and while stirring the aqueous suspension, an acid solution (Mg-based) is dropped to form a composite of hydrotalcite fine particles and fibers. Synthesized. Using an apparatus as shown in FIG. 2, the reaction temperature was 60 ° C., the dropping rate was 15 ml / min, and dropping was stopped when the pH of the reaction solution reached about 7. After completion of the dropping, the reaction solution was stirred for 30 minutes and washed with 10 times the amount of water to remove the salt, thereby obtaining Sample 2 (average primary particle size of inorganic particles: 20 nm). Sample 2 had an ash content of 47%.

(2) Manufacture of handmade sheet The manufactured composite was formed into a sheet by the following procedure. For reference, a handsheet was produced using LBKP (CSF: 370 ml). The basis weight of each sheet was measured based on JIS P 8124: 1998, and the ash content was measured based on JIS P 8251: 2003.

(Sheet 1 to Sheet 3)
In an aqueous slurry (about 0.5%) of the composite (samples 1-1 to 1-3), 100 ppm of a cationic retention agent (ND300, manufactured by Hymo), an anionic retention agent (FA230, manufactured by Hymo) ) Was added at 100 ppm and stirred at 500 rpm to prepare a suspension. Based on JIS P 8222, a composite sheet having a basis weight of 90 to 200 g / m ² was produced from the obtained suspension according to JIS P 8222.

(Sheet 4)
An aqueous slurry of the composite (sample 2) was prepared to 0.5%, and a basis weight of 450 g / m ² was used with a square hand-drawer based on JIS P 8222 without adding a retention agent. A body sheet was produced.

(Pulp sheet: Comparative example)
A sheet having a basis weight of about 130 g / m ² was produced using LBKP (CSF: 370 ml).

(3) Flame Retardancy Evaluation of Sheet The sheet flammability was evaluated based on JIS A 1322 (JIS Z 2150) according to the following procedure.

  Sheets cut to a certain size (sheets 1-3: 25 cm × 25 cm, sheet 4: 20 cm × 30 cm) are dried at 50 ° C. for 48 hours, and then left in a desiccator containing drying silica gel for 24 hours to burn It was set as the sample of a test (heating test).

  A sample is attached to a support frame (25 cm × 16 cm), mounted on a heating test apparatus so as not to sag, and after igniting a gas burner, the sheet 4 is heated for 30 seconds, the others are heated for 10 seconds, the carbonization length, Residual flame time and residual dust time were measured (FIG. 3).

For the combustion test, a 45 ° flammability tester (FL-45M manufactured by Suga Test Instruments Co., Ltd.) was used. For the heating, a Meckel burner (height 160 mm, inner diameter 20 mm) was used, and only the gas was fed and burned without mixing primary air. The fuel was liquefied petroleum gas No. 5 (mainly butane and butylene, JIS K 2240), and the length of the flame was adjusted to 65 mm with no sample attached.
-Carbonization length: The maximum length in the longitudinal direction of the support frame is measured for the portion of the heated surface of the test body where the carbonized portion (carbonized and the strength clearly changes).
-Residual flame time: Measure the time that the specimen keeps on burning after the end of heating.
-Residual dust: A state in which flameless combustion has occurred since the end of heating.

In addition, in JIS A 1322 (JIS Z 2150), the fire prevention grade regarding a flame retardance is defined as follows.
・ Fire protection grade 1: Carbonization length 5cm or less, no after-flame, no residue remaining after 1 minute ・ Fire protection grade 2: Carbonization length 10cm or less, no after-flame, no residue remaining after 1 minute ・ Fire protection grade 3: Carbonization 15cm or less, no after flame, no residual dust after 1 minute

  Table 1 and FIG. 4 show the results of heating with a gas burner for a certain period of time. As is clear from the results, sheets 1 to 3 (sheets made of a composite of magnesium carbonate and fiber) have a flame spread after ignition compared to a pulp sheet (sheet made of LBKP, upper left of FIG. 4). It was confirmed that there were few. In particular, for the sheet 2 (the sheet of the sample 1-2, the upper right of FIG. 4) and the sheet 3 (the sheet of the sample 1-3, the lower left of FIG. 4), the flame hardly burns and corresponds to the first grade of flameproofing. It was confirmed that it has flame retardancy. Moreover, it became clear that the sheet 4 (the sheet of the sample 2, the lower right in FIG. 4) has a flame resistance equivalent to a flameproof grade 2 at a combustion time of 30 seconds.

Experiment 2: Manufacture of composite board and evaluation of flame retardancy (1) Synthesis of composite (Sample 3-1: Composite of magnesium carbonate and fiber)
A composite of magnesium carbonate and fibers was synthesized in the same manner as Sample 1-3 (ash content: 49%, average primary particle size of inorganic particles: 1 μm).

(Sample 3-2: Composite of magnesium carbonate and fiber)
The amount of magnesium hydroxide charged was 5250 g, the type of kraft pulp used was LBKP (CSF = 500 mL, average fiber length = 0.76 mm), the amount of pulp charged was 3500 g, and the total amount of aqueous suspension was 170 L. Except for the above, synthesis was performed in the same manner as in Sample 1-1. The obtained composite had an ash content of 55%, and the average primary particle size of the inorganic particles was 0.8 μm.

(Sample 3-3: Composite of calcium carbonate and fiber)
Using a reactor as shown in the left of FIG. 5, a composite of calcium carbonate and fiber was synthesized by the carbon dioxide gas method. Ultra fine bubble generator (UFB generator, YJ-9) for 15 kg of aqueous suspension of 15 kg of calcium hydroxide (Okutama Kogyo, Tamaace U) and 15 kg of LBKP (CSF = 500 mL, average fiber length = 0.76 mm), The reaction liquid was circulated at a pump flow rate of 80 L / min using Envirovision, right in FIG. 5 (injection speed from the nozzle: 125 L / min · cm ² ). A large amount of fine bubbles (diameter: 1 μm or less, average particle size: 137 nm) containing carbon dioxide are generated in the reaction liquid by blowing carbon dioxide from the air supply port of the ultra fine bubble generator, and calcium carbonate is formed on the pulp fiber. Particles were synthesized. The reaction was carried out at a reaction temperature of 20 ° C. and the amount of carbon dioxide blown at 20 L / min, and the reaction was stopped when the pH of the reaction solution reached about 7 to obtain Sample 3-3 (the pH before the reaction was About 13). The obtained calcium carbonate and pulp fiber composite had an ash content of 57%, and the average primary particle size of the inorganic particles was 50 nm.

(Sample 3-4: Composite of barium sulfate and aluminum hydroxide and fiber)
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 Industry, 75 kg) was added and mixed, and then aluminum sulfate (sulfuric acid band, 98 kg) was added dropwise at about 500 g / min using a peristaltic pump. After completion of dropping, stirring was continued for 30 minutes to obtain a composite. The obtained composite had an ash content of 75%, and the inorganic particles had an average temporary particle size of about 100 nm.

(2) Production of composite sheet (Sheet 3-1)
In the same manner as in Experiment 1, a sheet was produced from the composite (sample 3-1) by hand-drawing (sheet 3-1A: basis weight 600 g / m ² , sheet 3-1B: 750 g / m ² ).

(Sheet 3-2)
After adjusting the slurry of Sample 3-2 to a concentration of about 1%, a cationic retention agent (ND300, Hymo) and an anionic retention agent (FA230, Hymo) were added at 100 ppm each as a solid content, and the paper stock A slurry was prepared. Subsequently, a sheet was produced from this stock slurry under a condition of a paper making speed of 10 m / min using a long paper machine (basis weight: about 150 g / m ² , ash content: about 46%).

(Sheet 3-3: Calcium carbonate complex)
Similarly to the sheet 3-2, a sample 3-3 was formed into a sheet using a long paper machine (basis weight: about 150 g / m ² , ash: about 45%).

(Sheet 3-4: LBKP only)
In the same manner as Sheet 3-2, LBKP (CSF = 500 mL, average fiber length = 0.76 mm) was formed into a sheet using a long net paper machine to obtain a sheet consisting only of LBKP (basis weight: about 150 g / m ² , Ash: 0%).

(Sheet 3-5)
Sample 3-4 (concentration: 1%) was prepared by adding a cationic retention agent (ND300, Hymo) and an anionic retention agent (FA230, Hymo) at a solid content of 100 ppm each. did. Next, a sheet was produced from this stock slurry using a long paper machine at a speed of 10 m / min. The basis weight of the obtained sheet was 180 g / m ² and the ash content was about 67%.

(Sheet 3-6)
A sheet was produced from the sample 3-2 in the same manner as the sheet 3-2 except that the basis weight was about 190 g / m ² (basis weight: about 190 g / m ² , ash content: about 46%).

(3) Production of composite board (Composite board A, basis weight: about 1700 g / m ² , FIG. 6A)
After pasting sheets 3-1A one by one using vinyl acetate binder on the front and back of a water-resistant base paper (made by Nippon Paper Industries, basis weight 500 g / m ² , thickness 0.76 mm, ash content 11%), The composite board was produced by pressing once (4.8 MPa) with a press machine.

(Composite board B, basis weight: about 2000 g / m ² , FIG. 6B)
A composite board was produced in the same manner as the composite board A, except that the sheet 3-1B was used instead of the sheet 3-1A.

(Composite board C, basis weight: about 1250 g / m ² , FIG. 6C)
A composite board was produced in the same manner as the composite board B except that the sheet 3-1B was bonded to only one side of the water-resistant base paper.

(Composite board D, basis weight: about 2000 g / m ² , FIG. 6D)
A composite board was produced in the same manner as composite board A, except that five sheets 3-2 were used per side.

(Composite board E, basis weight: about 2180 g / m ² , FIG. 6E)
Two sheets 3-2 were bonded between two water-resistant base papers (made by Nippon Paper Industries, basis weight 190 g / m ² , thickness 0.28 mm, ash content 11%), and the outside of the water-resistant base paper A composite board was prepared by laminating 5 sheets 3-2 each.

(Composite board F, basis weight: about 2000 g / m ² , FIG. 6F)
A composite board was produced in the same manner as the composite board D except that the sheet 3-3 was used instead of the sheet 3-2.

(Composite board G, basis weight: about 2000 g / m ² , FIG. 6G)
A composite board was produced in the same manner as the composite board D except that the sheet 3-4 was used instead of the sheet 3-2.

(Composite board H, basis weight: about 2250 g / m ² , FIG. 6H)
Three water-resistant base papers (manufactured by Nippon Paper Industries Co., Ltd., basis weight 750 g / m ² , thickness 1 mm, ash content 11%) were bonded to produce a bonded board.

(Composite board I, basis weight: about 1800 g / m ² , FIG. 6I)
Ten sheets 3-5 were bonded together with a vinyl acetate binder to prepare a composite board.

(Composite board J, basis weight: about 2560 g / m ² , FIG. 6J)
Two sheets of sheet 3-6 were bonded to the front and back of the composite board I to prepare a composite board.

  After producing the composite board, it was dried in an oven at 105 ° C. for one night or more, and then a heating experiment was performed under the same conditions as in Experiment 1. However, in this experiment, the carbonization area was measured instead of the carbonization length, and the heating time was 2 minutes. The carbonization area was calculated by measuring the maximum length and the maximum width of the carbonized portion (the strength was clearly changed by carbonization) on the heating surface of the test specimen, and multiplying them.

  The results of the heating test are shown in the table. Moreover, the external appearance photograph of the sample after a heating test is shown in FIG. As is clear from the experimental results, the composite board (A, B, D, E) in which the magnesium carbonate composite sheet is bonded to the front and back of the water-resistant base paper has a small carbonization area, after flame time, and residual dust time, The flame retardancy was excellent. Comparing composite boards B and C using the same magnesium carbonate composite sheet, the carbonization area and afterflame time were equal, but composite board C with magnesium carbonate sheet bonded to only one side had a residual time. It became long.

  On the other hand, the composite board F (calcium carbonate) and the composite board G (LBKP) both have a long residual time of 5 minutes or more, and the composite board H made of only water-resistant base paper has a residual flame and residual dust. The time was as long as 20 minutes or more, and the flame retardancy was low.

Further, the composite board I had a residual flame time of 20 seconds, but there was no residue and the carbonized area was relatively small. The composite board J in which the magnesium carbonate sheets are bonded to the front and back has a residual flame time of 10 seconds or less, a residual dust time of 30 seconds or less, and a carbonized area of 50 cm ² or less. The standard required for flameproof articles (plywood) Satisfies (Fire Service "Knowledge and practice of flameproofing").

Claims (8)

  A flame retardant comprising a composite of flame retardant inorganic particles and fibers.   The flame-retardant material according to claim 1, wherein the fibers are cellulose fibers.   The flame-retardant material according to claim 1 or 2, wherein the flame-retardant inorganic particles are selected from the group consisting of magnesium carbonate, barium sulfate, aluminum hydroxide, and hydrotalcite.   The flame retardant according to any one of claims 1 to 3, which is in the form of a sheet.   The flame retardant according to any one of claims 1 to 4, wherein a composite sheet of flame retardant inorganic particles and fibers is laminated.   The flame retardant according to any one of claims 1 to 5, wherein a composite sheet of flame retardant inorganic particles and fibers is bonded to a substrate.   The flame retardant material according to claim 1, wherein the average primary particle diameter of the flame retardant inorganic particles is 1.5 μm or less.   The flame retardant material according to any one of claims 1 to 7, wherein a weight ratio of the flame retardant inorganic particles and the fibers is 5/95 to 95/5.