JP2016055620A - Fiber board and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber board having excellent dimensional stability and excellent planar tensile strength, prepared with a binder which has high adhesion and can be cured in a short time, and a method for producing the same.SOLUTION: A fiber board is obtained by heating and pressurizing, and then molding a mixture of a binder comprising powdery saccharides and powdery divalent or more acids and a plant fiber, where the binder has powdery inorganic substance added thereto.SELECTED DRAWING: None

Description

  The present invention relates to a fiber board and a manufacturing method thereof.

  Wood based boards such as particle board (PB) and medium density fiber board (MDF) are used in a wide range of fields as building materials. These are made from waste wood used during lumbering, low-quality chips not used in papermaking, small pieces of wood obtained from building demolition materials, etc. It is an environmentally friendly material. In addition, it has characteristics such as stable quality, less anisotropy and good workability compared to a sawing board obtained by sawing wood.

  Thermosetting resin adhesives such as urea resin adhesives, melamine resin adhesives, phenol resin adhesives and the like are usually used as wood adhesives used in the production of these wood boards. These general wood adhesives are derived from petroleum, and formaldehyde is used as a curing agent. Moreover, these are required to be aqueous in order to suppress the diffusion of the organic solvent.

  However, these petroleum-derived adhesives have recently been problematic in terms of formaldehyde emission, and although reduction measures have been taken, formaldehyde emission cannot be completely suppressed. Petroleum-derived isocyanate-based adhesives that do not disperse formaldehyde have been developed. However, reaction with moisture, bonding with metals, and the like are problems and are not widely used.

  Under these circumstances, considering the emission of formaldehyde, etc., it has been studied to use a plant-derived material and polycarboxylic acid or a composition mainly composed of plant-derived material, polycarboxylic acid and saccharide as an adhesive for wood. Yes.

  However, these woody adhesives, for example, when used for flooring materials, are hardly satisfactory in physical properties such as peel strength and water absorption thickness swelling rate, and achieve physical properties such as strength that can withstand practical use. To do this, it was necessary to optimize the long molding time, heating time, and components.

  In addition, an adhesive containing a Maillard reaction product of an amine such as an ammonium salt of a polycarboxylic acid and a carbohydrate such as a saccharide has been studied, but this is due to a Maillard reaction of an amine and a saccharide, and is inexpensive. The polycarboxylic acid cannot be used as it is.

  Therefore, in order to solve the above problems, a fiber board manufacturing method is proposed in which a high-adhesive composition using saccharide powder and polyvalent carboxylic acid and a vegetable fiber are mixed and heated and pressure-molded. (For example, refer to Patent Document 1).

JP 2014-51568 A

  According to the proposal described in Patent Document 1, it is excellent in terms of manufacturing a fiber board using an adhesive composition that has excellent adhesive strength, can be cured in a short time, and has good dimensional stability after curing. It is supposed to be. However, in the course of production, when the bonding composition composed of saccharides and polyvalent carboxylic acid and the fiber are mixed, it may be difficult to supply the bonding composition to the details of the fiber. When molded into a fiber board, the adhesive strength of the portion where the adhesive composition is not supplied between the fibers is weak, so the physical properties of the plane tensile strength may be inferior, and there is still room for improvement in this regard. It was.

  The present invention has been made in view of the above-mentioned conventional problems, and has excellent dimensional stability and excellent flat tensile strength using a binder that has high adhesiveness and can be cured in a short time. It is an object to provide a board and a manufacturing method thereof.

  The present invention is characterized by the following in order to solve the above problems.

  That is, the fiber board of the present invention is a fiber board formed by heating and pressing a mixture of powdered saccharide and powdered divalent or higher acid binder and vegetable fiber, It is characterized by adding a powdery inorganic substance.

  The fiber board production method of the present invention is a method for producing a fiber board containing a binder containing a saccharide powder, a divalent or higher acid acid of powder and an inorganic powder, and a vegetable fiber, After mixing the components, the plant fibers are mixed and heat-pressed.

  The fiber board production method of the present invention is a method for producing a fiber board containing a binder containing a saccharide powder, a divalent or higher acid acid of a powder, and a powder inorganic substance, and a vegetable fiber, After mixing plant fiber, it mix | blends the components of binders other than an inorganic substance, and it heat-press-molds.

  According to the present invention, it is possible to provide a fiber board excellent in dimensional stability and excellent in plane tensile strength, and a method for producing the same, using a binder that has high adhesiveness and can be cured in a short time. Become.

  The fiber board of the present invention will be described in detail below with reference to modes for carrying out the invention. The fiber board of the present embodiment is a fiber board formed by heating and pressing a mixture of a powdered saccharide and a powdered bivalent or higher acid binder and a vegetable fiber. And the inorganic substance of a powder is added to the binder. First, a description will be given of a binder and a vegetable fiber containing a powdered saccharide as an essential component, a divalent or higher acid of the powder, and a powdered inorganic material as an additive.

  As saccharides, monosaccharides and disaccharides, oligosaccharides or polysaccharides constituted by glycosidic bonds of monosaccharides can be used. Examples of monosaccharides include those containing fructose, ribose, arabinose, rhamnose, xylulose, deoxyribose and the like. Among these, those containing fructose can be suitably used. By using a fructose-containing monosaccharide, fructose can form a furan ring polymer via a furan ring, so that the reactivity can be improved and cured under short heating and pressing conditions. it can.

  Specifically, fructose is denatured into a compound having a furan ring such as hydroxymethylfurfural, furfural, furfuryl alcohol, etc. by heating with a divalent or higher acid (polybasic acid) described below, especially a polyvalent carboxylic acid. Cheap. It is considered that a compound having a furan ring condenses with a compound having a furan ring using a divalent or higher acid (polyvalent carboxylic acid) as a catalyst and easily forms a polymer cured product by an ester bond.

  By forming such a cured polymer, excellent adhesiveness can be exhibited. The content ratio of fructose is 50% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more of the total amount of saccharides.

  Examples of the disaccharide include sucrose, maltose, trehalose, tulanose, lactulose, maltulose, palatinose, gentiobiulose, melibiurose, galactosucrose, lutinulose, planteobiose and the like.

  Examples of the oligosaccharide include fructooligosaccharide, galactooligosaccharide, mannan oligosaccharide, stachyose and the like.

  Examples of the polysaccharide include starch, agarose, alginic acid, glucomannan, inulin, chitin, chitosan, hyaluronic acid, glycogen, and cellulose.

  Moreover, it is preferable to contain the disaccharide containing a fructose residue as saccharides other than the fructose of monosaccharide. Examples of the disaccharide containing a fructose residue include lactulose, tulanose, maltulose, palatinose, gentiobiulose, melibiurose, galactosucrose, rutinulose, and planteobiose.

  Although these disaccharides containing fructose residues are inferior to monosaccharide fructose, the same effects as those obtained when fructose is contained can be obtained.

  One type of saccharide other than the monosaccharide fructose may be used, or two or more types may be used in combination.

  In addition, mixed sugars and isomerized sugars containing fructose can also be used. Among them, isomerized sugar can be preferably used because it can be obtained at a lower cost than fructose alone. Fructose, also called fructose, is produced from fruit juice and honey, but the main production method is to saccharify starch produced from corn, potato, sweet potato, tapioca, etc. into glucose with the enzymes amylase and glucoamylase. In this method, glucose is isomerized to fructose using another enzyme, glucose isomerase, to obtain an isomerized sugar in which fructose and glucose are mixed. By purifying this isomerized sugar, it is possible to produce an isomerized sugar having a high fructose ratio or a fructose having a high purity. It is also called glucose fructose liquid sugar, fructose glucose liquid sugar, high fructose liquid sugar, etc. depending on the fructose ratio.

  As the divalent or higher acid (polybasic acid), a polyvalent carboxylic acid can be preferably used. The polyvalent carboxylic acid can be used without particular limitation as long as it is a compound having a plurality of carboxyl groups, and specific examples thereof include the following.

  Citric acid, tartaric acid, malic acid, succinic acid, oxalic acid, adipic acid, malonic acid, phthalic acid, sebacic acid, maleic acid, fumaric acid, malonic acid, itaconic acid, glutaric acid (1,5-pentanedioic acid), Gluconic acid, glutaconic acid, pentenedioic acid and the like. An anhydride can also be used.

  Among polyvalent carboxylic acids, citric acid, tartaric acid, malic acid, gluconic acid, sebacic acid, itaconic acid and the like are preferable because they are produced from plants, and citric acid is particularly preferable from the viewpoint of availability. Can be used. Moreover, these may be used individually by 1 type and may use 2 or more types together.

  The above saccharides and divalent or higher acids are powders, and are powders having an average particle size of 30 μm or less, preferably 5 to 20 μm. The saccharide and the divalent or higher acid may be used as the above average particle size range, but after mixing each into a mixture in advance, pulverizing and adjusting to the above average particle size range Also good.

  By setting the average particle size of the powder within the above range, a fiber board that is dispersed almost uniformly with plant fibers and has excellent plane tensile strength can be obtained.

  The blending ratio of the powdered saccharide and the powdered divalent or higher acid is 10 to 90% of the powdered saccharide when the total of the powdered saccharide and the powdered divalent or higher acid is 100 parts by mass. It is preferable that the mass is preferably in the range of 20 to 80 parts by mass, and the divalent or higher acid of the powder is in the range of 90 to 10 parts by mass, preferably 80 to 20 parts by mass.

  By setting the blending ratio of the divalent or higher acid of the powder to 10 parts by mass or more, the carboxyl group of the divalent or higher acid of the powder that contributes to the reaction with the saccharide of the powder does not decrease too much and is cured. It becomes easy and high adhesiveness can be obtained.

  In addition, if the blending ratio of the divalent or higher acid in the powder is 20 parts by mass or more, even if there is a carboxyl group that does not contribute to the reaction of the powder with the saccharide, it reacts with the saccharide in the plant fiber and the plant. Since the amount of hydroxyl groups in the fiber decreases, the water resistance after molding can be improved. Moreover, if the blending ratio of the divalent or higher acid in the powder is 80 parts by mass or less, the reaction between the polyvalent carboxylic acid and the saccharide of the powder in the plant fiber is relatively more reactive with the saccharide of the powder. Increases, the amount of the cured polymer formed increases, and the adhesion can be improved.

  As a kind of the inorganic substance of the powder added to the binder, a generally known inorganic powder can be used. Specifically, powders, such as a calcium compound, a silica, a magnesium compound, an aluminum compound, can be mentioned, for example. Among these, calcium carbonate, which is a calcium compound, can be suitably used from the viewpoint of being inexpensive and easily available. Moreover, the inorganic substance of a powder may be used individually by 1 type in consideration of the dispersibility etc. at the time of mixing with a vegetable fiber, and may use 2 or more types together.

  The average particle size of the inorganic powder is about the same as that of the saccharide and divalent or higher acid powder, that is, the average particle size is 30 μm or less, preferably 5 to 20 μm. It is preferable to make it smaller than the average particle diameter.

  The powder average particle size of the powdered saccharide, the powdered divalent or higher acid, and the powdered inorganic substance can be measured by, for example, a laser diffraction / scattering method using a commercially available laser diffraction / scattering type particle size distribution measuring device. Can be obtained as a median diameter (d50, volume basis) by cumulative distribution.

  The blending ratio of the inorganic substance in the powder is in the range of 50 to 200 parts by mass when the total amount of the saccharide in the powder and the divalent or higher acid in the powder is 100 parts by mass.

  By adding a powder inorganic substance to the binder and setting the average particle size and blending ratio of the powder inorganic substance within the above ranges, the powder inorganic substance and the plant fiber are mixed with each other at the time of production. Plant fibers are unwound by contact. And it becomes possible to supply a binder uniformly to the fine detail between the plant fibers disaggregated finely, and when it is set as the fiber board, the outstanding plane tensile strength can be expressed.

  In addition to the powdery inorganic substance, a powdery thermosetting resin composition can also be added to the binder. The powder thermosetting resin composition can be used without particular limitation as long as it is a commonly known powder thermosetting resin composition. Examples of these include a thermosetting resin composition in the form of a powder containing a thermosetting resin such as a urea resin, a phenol resin, a melamine resin, an epoxy resin, a urethane resin, and an unsaturated polyester resin. The powder thermosetting resin composition is obtained by heating an individual thermosetting resin at room temperature, mixing it with a curing agent, forming a B-stage, cooling and grinding. By blending the powder thermosetting resin composition, the adhesive strength of the binder can be improved, and a fiber board having excellent flat tensile strength can be obtained.

  Furthermore, p-toluenesulfonic acid can be added to the binder. This paratoluenesulfonic acid has a catalytic function as a reaction accelerator. The mixing ratio of p-toluenesulfonic acid is not particularly limited, but when the total amount of powdered saccharide and powdered divalent or higher acid is 100 parts by mass, it is usually 3 to 20 parts by mass. preferable. By blending p-toluenesulfonic acid, it is possible to cure further in a shorter time.

  Since paratoluenesulfonic acid has a hygroscopic property, when paratoluenesulfonic acid is added to the binder, the sugars in the powder become viscous due to moisture absorption by the paratoluenesulfonic acid, causing the binder to agglomerate. Mixing with fibers may be difficult. Therefore, when adding para-toluenesulfonic acid to a binder, it is preferable that the inorganic substance of a powder contains a silica, a talc, or a zeolite. The content ratio of silica, talc, or zeolite in the inorganic powder is not particularly limited, but is usually 10 to 100 when the total amount of saccharide in the powder and divalent or higher acid in the powder is 100 parts by mass. It is preferable to set it as a mass part.

  As described above, when the inorganic substance of the powder contains silica, talc, or zeolite, even if paratoluenesulfonic acid added to the binder absorbs moisture, aggregation of the binder hardly occurs. Therefore, when mixed with plant fibers, it is possible to suppress the loss of the dispersibility of the binder, the catalytic function of paratoluenesulfonic acid can be obtained more effectively, and the excellent adhesiveness of the binder can be expressed. Can do. Moreover, since the material loss by a binder adhering inside the manufacturing apparatus of the mixture of a binder and a vegetable fiber can be reduced, the improvement effect of the productivity of a fiber board is also anticipated.

  In addition, when paratoluenesulfonic acid is added to the binder and silica, talc, or zeolite is contained in the powdered inorganic material, the paratoluenesulfonic acid and the powdered inorganic material containing silica, talc, or zeolite are previously added. It is preferable to add the mixture to the other components of the binder. By doing in this way, the inhibitory effect of the binder aggregation described above can be obtained more effectively.

  Examples of plant fibers that can be used include hemp-based natural fibers, palm fibers, agricultural waste fibers, and wood fibers.

  Hemp-based natural fibers are plant fibers made from bast fiber-based plants such as kenaf, jute, flax, ramie, hemp, and sisal. Bast fiber-based plants are already distributed as general industrial raw materials in the spinning and nonwoven fabric industries, and can be stably procured. By mechanically defibrating the fiber bundle obtained from the bast portion of this bast fiber plant, fibers having high strength and excellent dimensional stability can be obtained.

  Further, by appropriately determining the defibrating conditions, the fiber bundle can be defibrated to a predetermined fiber length and fiber diameter, and the target plant fiber can be obtained relatively easily. When obtaining the target hemp natural fiber from the bast fiber plant, for example, it can be obtained according to the following procedure.

  First, a bast fiber bundle having a length of several tens of cm to several m and a width of about 5 mm to 30 mm is collected from the bast portion of the bast fiber plant. Next, the bast fiber bundle is cut so as to have a length of about 5 to 10 cm using a rotary cutter or the like. Next, the bast fiber bundle is defibrated using a lapping machine or the like until the target average fiber length and average fiber diameter are obtained.

  A repelling machine is a machine that has a mechanism in which a cylinder equipped with a pin with a sharp tip and a cutting blade rotates at high speed. By passing the fiber bundle through this anti-wool machine, the bundled fiber bundle is separated. Can be defibrated and fiberized.

  Palm fiber is fiber made from plants such as oil palm and coconut palm. This plant material can also be procured stably. High strength by defibrating the fiber part after squeezing palm oil from the fruit bunches such as oil palm and coconut to the prescribed fiber length and fiber diameter, similar to the bast fiber bundle described above Can be easily obtained.

  Agricultural waste fiber is a fiber made from agricultural waste such as sugar cane, corn, bamboo, and rice. For example, a bagasse fiber having a small bulk density can be obtained by drying a squeezed residue (hereinafter referred to as bagasse) after boiling sugar from sugarcane and then processing it into a fiber. Then, similarly to the bast fiber bundle described above, the target fiber can be easily obtained by defibrating to a predetermined fiber length and fiber diameter. Bagasse has conventionally been discarded or used as boiler fuel, paper raw materials, livestock feed, fertilizer, and the like, but has recently attracted attention as an available biomass resource due to increasing environmental problems.

  In addition to bagasse, the desired agricultural waste fibers can be obtained by defibrating corn, bamboo stalks, rice straw and other raw materials. By using raw materials that have been discarded in the past, waste can be reduced and valuable resources can be saved. In addition, the cost of the fiber board can be reduced.

  Wood fiber is a fiber made from conifers, hardwoods, and the like. The wood fiber can use miscellaneous trees, woodwork scraps, waste materials, defective timbers, thinned wood, etc., which are generally used as MDF raw materials. For this reason, it is possible to effectively use wood-based raw materials that are valuable resources from the viewpoint of the global environment. Similar to the above-mentioned bast fiber bundle, by defibrating such a wood-based raw material to a predetermined fiber length and fiber diameter, the target plant fiber can be easily obtained.

  Among the above plant fibers, hemp-based natural fibers can be preferably used from the viewpoint of further improving the strength and dimensional stability of the fiber board and obtaining the fiber board at a lower cost. In addition, the plant fiber can be used by appropriately combining plant fibers such as hemp-based natural fiber, palm fiber, agricultural waste fiber, and wood fiber.

  The average fiber length of the plant fiber is in the range of 5 to 100 mm, preferably 10 to 70 mm, more preferably 30 to 60 mm, and the average fiber diameter is 70 to 400 μm, preferably 100 to 350 μm, more preferably 150 to 300 μm. Range. By setting the average fiber length and the average fiber diameter within these ranges, a fiber board having excellent strength and dimensional stability can be obtained due to the entanglement of plant fibers.

  The average fiber length can be measured using a fiber length distribution measuring machine or the like. The average fiber diameter can be measured as an average value obtained by measuring fiber diameters at a plurality of locations from an image of an optical microscope or an electron microscope.

  Further, it is desirable that the moisture content of the plant fiber is 5% or less, preferably 3% or less. If the moisture content of the plant fiber is higher than 5%, the moisture absorption amount of sugars and divalent or higher acids increases, and the particles tend to aggregate. As a result, the dispersibility with the plant fiber is lowered, and the plane tensile strength is easily lowered. In addition, adjustment of the moisture content of a vegetable fiber can be performed using a vacuum dryer, a thermo-hygrostat, etc.

  Below, embodiment of the manufacturing method of a fiber board is described.

  First, plant fibers defibrated to a predetermined average fiber length and average fiber diameter and adjusted to a predetermined moisture content are mixed with a binder containing at least a powdered saccharide, a powdered divalent or higher acid, and a powdered inorganic substance. To obtain a mixture. The blending ratio of the binder and the vegetable fiber can be blended so that the component of the binder is 5 to 40 parts by mass, preferably 10 to 30 parts by mass with respect to 100 parts by mass of the plant fiber.

  Here, in manufacture of a mixture, all the components of a vegetable fiber and a binder can be added at once, and it can mix with a small cotton blender etc. which have a cylinder with a pin, and can be made into a mixture.

  Alternatively, after preparing a binder mixture in which only the binder components are mixed in advance, the binder mixture and fibers can be mixed to form a mixture. Thus, by mixing the binder mixture prepared in advance with the vegetable fiber, all the binder components can be mixed with the vegetable fiber uniformly, and a fiber board having a superior plane tensile strength can be obtained. it can. As described above, by mixing the binder containing the inorganic powder and the plant fiber, the plant fiber is released by contact and friction between the inorganic powder and the plant fiber. And it becomes possible to disperse each powder of sugar and divalent or higher acid evenly in the details between the undissolved plant fibers, and when it is made into a fiber board, it exhibits excellent plane tensile strength Can do.

  Moreover, after mixing a powdery inorganic substance and a vegetable fiber in advance and dissolving a plant fiber, the component of binders other than this inorganic substance can also be mixed and it can also be set as a mixture. In this way, by mixing only the inorganic powder and the plant fiber in advance, the plant fiber can be unraveled particularly well by contact and friction between the inorganic powder and the plant fiber. And it becomes possible to disperse each powder of sugar and divalent or higher acid evenly in the details between the undissolved plant fibers, and when it is made into a fiber board, further excellent plane tensile strength is expressed. be able to.

  Next, the obtained mixture is formed into a mat to form a fiber mat. For making the mixture into a fiber mat, for example, an apparatus called a mat former that continuously produces fiber mats can be used. The fiber mat can also be formed by a method such as spraying a mixture on a mold.

  Next, the formed fiber mat is heated and pressed to form a fiber board. For heating and pressure forming of the fiber mat, for example, a continuous press device that conveys the fiber mat while applying pressure to a gap between a pair of heated steel belts, or heating by placing the fiber mat between a plurality of heated hot plates. A pressurizing multi-stage press apparatus or the like can be used. The molding conditions can be appropriately determined depending on the type of the binder and the surface weight of the fiber mat, and are not particularly limited, but a temperature range of 140 to 230 ° C. and a pressure of 1 to 5 MPa is preferable. The heating and pressing time can be appropriately determined according to the thickness of the fiber board and the forming temperature.

  In addition, if necessary, a mat heat treatment for heating the fiber mat may be performed before the heat and pressure molding to melt the binder in the fiber mat. As a result, the molten binder can be held while being uniformly dispersed in the voids of the aggregate in which the plant fibers are intertwined. Thereby, when handling a fiber mat, such as conveying a fiber mat, it becomes possible to suppress omission and segregation of a binder.

  Next, post-processing such as adjusting the moisture content (curing) or cutting into a predetermined size is performed on the fiber board obtained after molding, as necessary.

  The fiber board manufactured in this way can be made into a fiber board excellent in strength, dimensional stability and planar tensile strength by effectively bonding the fibers together with a binder.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.
(Example 1)
As a plant fiber, a bute fiber bundle of jute (width: 1 to 2 cm, length: 2 to 4 m) was cut in the length direction by a cutting machine, and then mechanically defibrated using a lapping machine. As a result, jute plant fibers having an average fiber length of about 55 mm and an average fiber diameter of about 150 μm were obtained.

Next, the components of the binder were mixed in advance, and then the plant fiber and the binder were put into a small cotton blender having a pinned cylinder, and mixed so that the fibers and the binder were uniform to obtain a mixture. Each component of the binder used the following, and it was set as the mixture ratio shown in Table 1.
Sugar of powder: Fructose (manufactured by Wako Pure Chemical Industries) (average particle size of about 20 μm)
Divalent or higher acid of powder: Citric acid (manufactured by Wako Pure Chemical Industries, Ltd.) (average particle size of about 20 μm)
Powder inorganic substance: Calcium carbonate (Wako Pure Chemical Industries, Ltd.) (average particle diameter of about 20 μm)
Reaction accelerator: p-toluenesulfonic acid (manufactured by Wako Pure Chemical Industries).

  Next, this mixture was sprinkled on the mold using a simple forming device (inner size in mold: 30 cm square) to form a mat, thereby obtaining a fiber mat. Here, the spraying amount of the mixture was adjusted so that the weight of the obtained fiber mat was about 263 g.

Next, this fiber mat is heated and pressed under the conditions of a temperature of 200 ° C., a pressure of 20 kg / cm ² , and a time of 5 minutes using a small hot press machine, and a 30 cm square size, 4.5 mm thick fiber. Got the board. The density of this fiber board was about 650 kg / m ³ .
(Example 2)
As a method for producing the mixture, a fiber board was produced in the same manner as in Example 1 except that a powdery inorganic substance and vegetable fiber were mixed in advance and then mixed with a binder component other than the inorganic substance to obtain a mixture.
(Example 3)
A fiber was formed in the same manner as in Example 1 except that a powdered phenol resin (average particle diameter of about 20 μm) containing a novolac type phenol resin as a thermosetting resin composition as a resin component was added to the binder in the ratio shown in Table 1. A board was produced.
(Comparative Example 1)
A fiber board was produced in the same manner as in Example 1 except that the inorganic powder was not mixed with the binder.

  About the fiber board produced in said Examples 1-3 and the comparative example 1, the plane tensile strength was measured. The plane tensile strength was measured four times in accordance with JIS A 5908: 2003 (6.11), and the average value was calculated. The results are shown in Table 1.

  From this result, it was confirmed that the plane tensile strengths of the fiber boards of Examples 1 to 3 were very excellent as compared with Comparative Example 1. This is thought to be due to the fact that the plant fibers were unwound by the addition of the inorganic powder, and the components of the undissolved plant fibers and the binder were uniformly dispersed, thereby contributing to the improvement of the planar tensile strength.

  In addition, the fiber board of Example 2 was confirmed to have further improved planar tensile strength as compared with Example 1. This is a mixture of mineral powder and plant fiber in advance, so that the plant fiber can be efficiently unwound, and the components of the binder can be dispersed to the details between the undissolved plant fibers. it is conceivable that.

  In addition, the fiber board of Example 3 in which the powder thermosetting resin composition was added to the binder was further confirmed to have an improved planar tensile strength compared to Examples 1 and 2. This is presumably because the adhesive strength of the binder was improved by adding a powdered thermosetting resin, and an excellent flat tensile strength was developed.

From these results, according to the fiber board of the present invention and the method for producing the same, by using a binder containing a powdery inorganic substance that has high adhesiveness and can be cured in a short time, it has excellent planar tensile strength. It was confirmed that the obtained fiber board can be obtained.

Claims (9)

  A fiber board formed by heating and pressing a mixture of a powdered saccharide and a powdered divalent or higher acid binder and a vegetable fiber, wherein the powdery inorganic substance is added to the binder. A fiber board characterized by   2. The fiber board according to claim 1, wherein the saccharide of the powder and the divalent or higher acid of the powder each have an average particle diameter of 20 μm or less.   The fiber board according to claim 1 or 2, wherein the moisture content of the plant fiber is 5% or less.   The fiber board according to any one of claims 1 to 3, wherein the inorganic substance of the powder includes a powder of a calcium compound.   The fiber board according to any one of claims 1 to 4, wherein a powder thermosetting resin composition is further added to the binder.   The fiberboard according to any one of claims 1 to 5, wherein p-toluenesulfonic acid is further added to the binder.   The fiber board according to claim 6, wherein the inorganic substance of the powder contains silica, talc or zeolite.   A method for producing a fiber board comprising a binder containing a saccharide powder, a divalent or higher acid acid and a powder inorganic substance, and a vegetable fiber, wherein the vegetable fiber is mixed after the components of the binder are mixed. A method of manufacturing a fiber board, characterized by heating and pressing. A binder comprising powdered saccharides, powdered divalent or higher acid and powdered inorganic material, and a fiber board manufacturing method comprising vegetable fiber, wherein the inorganic material and the vegetable fiber are mixed, and then other than the inorganic material A method for producing a fiberboard, comprising mixing the components of the binder and heating and pressing.