JPH09209299A - Composite board and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composite board practically usable as a substitute for a wood-based material by reutilizing waste gypsum board available as an industrial waste. SOLUTION: The composite board is a formed and cured material or its bonded material produced by hot-pressing a composition composed of 15-80wt.% of a cellulosic fiber, 5-40wt.% of an inorganic filler and 10-45wt.% of a thermosetting resin and satisfying the relationship of Sf/Sp=0.05 to 10.0 wherein Sp is the total surface area of the cellulosic fiber and Sf is that of the inorganic filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a lightweight material which effectively utilizes cellulosic fibers and inorganic fillers, particularly gypsum board waste materials, as an alternative material for wood-based or wood-based materials (hereinafter simply referred to as wood-based materials). The present invention relates to a composite plate having excellent strength and good workability, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, wood-based materials that have been used in large amounts in the field of construction and civil engineering are expected to make it difficult to obtain wood in the near future from the viewpoint of depleting global wood resources and protecting the natural environment. is expected.

Further, the gypsum board with the fibrous surface material, which is widely used like the wood-based material, accounts for about 20% of the production amount.
Is generated as a waste material, and a part of the waste material generated at the production site is reused as a substitute raw material for the gypsum component after peeling the face material, that is, the paper, and pulverizing it. However, since the crushed product of the gypsum board waste material generated from the distribution process or the construction site generally contains a cellulose fiber component derived from a face material, the current gypsum board manufacturing method using a high-concentration gypsum slurry produces The limit of use is about 10% by weight, which does not cause deterioration of slurry flow that affects the property, and most of them are disposed of as industrial waste without being reused. Furthermore, in recent years, the problem of securing a disposal site has become involved, and it is being watched as a serious situation.

Further, as a method for producing flame-retardant paper or flame-retardant board, cellulose fiber, hydrous inorganic compound, powdered synthetic resin, and glass fiber are blended into a papermaking product, and a paper product is laminated on the surface of the molded product in some cases. Is also known (Japanese Patent Laid-Open No. Hei 4)
-185799). However, when the glass fiber is used to obtain the fiber reinforcing effect as described above, unlike the cellulose fiber, the workability, particularly the resistance during cutting becomes a problem. That is, there is no problem if the glass fibers are dispersed in a single fiber state, but when dispersed in the molded body while several to several tens of fibers are converged, a large resistance is intermittently exhibited, and smooth cutting is difficult. become. Further, if cutting is further forced, there is a high possibility that the hardened tissue around the converged glass fiber will be destroyed. Further, the fine glass fibers having a diameter of 4 μm or less used in this molded body are partly powdered and float in the dust generated during processing, which deteriorates the working environment. It is feared that the pulverized glass fiber may adhere to workers, cause itch associated with it, and may cause skin diseases, which may affect the human body. Further, as with asbestos, there is a view that it affects lung function, and it is not acceptable as an industrial product for cutting and processing applications.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides, as an alternative material to a wood-based material, a composite plate composed of a cellulosic fiber, an inorganic filler and a thermosetting resin,
A composite plate that is made of waste gypsum board, whether or not it has a face material, and that is lightweight, has excellent strength, and has good workability (saw workability, machinability such as drilling, and nailing). And to provide a method for manufacturing the same.

[0006]

In order to solve the above-mentioned problems, the present invention provides a cellulosic fiber of 15 to 80% by weight, an inorganic filler of 5 to 40% by weight, and a thermosetting resin of 10 to 45% by weight. % Of the total surface area Sp of the cellulosic fiber (Sf / Sp) in a cured molded article or a joined body obtained by heating and pressing a blended body of 0.05 to 10.0. The present invention provides a composite plate characterized by the following. The present invention also provides a step of preparing a slurry composed of a cellulosic fiber, an inorganic filler, a thermosetting resin and water (wherein the ratio of the total surface area Sf of the inorganic filler to the total surface area Sp of the cellulosic fiber (Sf / Sp) is from 0.05 to 10.0), a step of preparing a curable molded article by drying a wet molded article obtained by forming the slurry, and a single or a plurality of the curable molded article. A method of manufacturing the above composite plate, which comprises a step of heating and pressing after lamination to prepare a cured molded article or a joined body thereof. Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The cellulosic fiber used in the present invention functions to impart wood texture, strength and processability to a composite board. Preferred examples of the cellulosic fiber include wood pulp. , Linter pulp, hemp pulp, straw pulp, cotton pulp, and other pulps and pulp scraps, and fibers derived from plant fiber-based waste paper, such as newspaper, magazines, telephone directories, and corrugated cardboard. However, the present invention is not limited to these. These may be used alone or in combination of two or more.

The inorganic filler used in the present invention improves the workability (particularly the machinability) of the composite plate by combining it with the above-mentioned cellulosic fibers. Examples of such an inorganic filler include calcium carbonate, Silica powder, kaolin, clay, titanium oxide, barium sulfate, gypsum, aluminum hydroxide, talc, mica, glass flakes, hydrosaltite, wollastonite, potassium titanate, basic magnesium sulfate, sepiolite, xonotlite, aluminum borate In addition to perlite, shirasu balloon, waste glass foam and fly ash, crushed gypsum board waste material, crushed blast furnace slag, crushed waste glass, etc. are exemplified, but not limited thereto.
The term "crushed gypsum board waste material" used here refers to the waste of gypsum board such as defective products, lost products and used products that occur during the process from production of gypsum board to distribution and the construction site. Regardless of the presence or absence, it means a powder obtained by pulverizing with a suitable pulverizer and classifying if necessary.

Among these inorganic fillers, those having a Mohs hardness of 5 or less, preferably 1 to 5, are preferably used from the viewpoints of reducing the mechanical blade wear of the processing machine and contributing to the workability. . Examples of such inorganic fillers include, for example, calcium carbonate, kaolin, clay, barium sulfate, gypsum, talc, mica, hydrosaltite, wollastonite, potassium titanate, basic magnesium sulfate, sepiolite, xonotlite, gypsum board. Examples include crushed waste materials. Among them, the gypsum board waste material pulverized product is particularly preferable from the viewpoints of meeting the social needs of recycling the waste material, low cost, and the function of imparting flame retardancy. These inorganic fillers may be used alone or in combination of two or more. Further, such an inorganic filler is preferably adjusted to a particle diameter of 0.3 mm or less in order to avoid strength reduction and surface smoothness deterioration due to the inclusion of coarse particles.

The thermosetting resin used in the present invention has a binding function of binding and holding the cellulosic fibers and the inorganic filler by thermosetting in the presence or absence of a crosslinking agent. Examples of such thermosetting resins include phenol resins, epoxy resins, unsaturated polyester resins, melamine resins, urea resins and the like. Above all, a phenol resin having excellent heat resistance, flame resistance and rigidity is preferable. These may be used alone or in combination of two or more. The thermosetting resin is usually used in the form of powder or fibrous solid, but if necessary, it may be used in the form of a solution, a resin liquid, or a solid-liquid combination.

The phenolic resin as used herein is a condensation product of phenols and aldehydes or a modified product thereof and is heat-cured in the presence or absence of a curing agent to bond and retain cellulosic fibers and inorganic fillers. As the thermosetting phenolic resin, which has a binder function,
Examples thereof include novolac type phenol resin, methylol group-containing novolac type phenol resin, alkali resol type phenol resin, ammonia resol type phenol resin, and benzylic ether type phenol resin. Furthermore, it is obtained by mixing or reacting these phenolic resins with a thermosetting or thermoplastic compound such as an epoxy compound, a xylene compound, a melamine compound, a urea compound, an acrylic compound, a vinyl acetate compound. Examples include modified phenolic resins. These may be used alone or in combination of two or more. When the novolac type phenol resin is used alone, it is necessary to impart thermosetting property by using a crosslinkable curing agent such as hexamethylenetetramine.

Among such thermosetting phenolic resins, the methylol group-containing novolac type, alkali resol type, ammonia resol type and benzylic ether type phenolic resins are crosslinkable in terms of odor of the composite plate and ease of production. It is more advantageous than the novolac type phenolic resin which must use a curing agent together. In particular, the benzylic ether type phenol resin is preferably used because it has heat stability and color stability superior to those of other resins and can suppress deterioration of the wet molded body described later when it is dried. The form of use of the thermosetting phenolic resin is not particularly limited, but it is generally a powdery or fibrous solid, and is used as a solution or a resin liquid or in combination with solid-liquid as required.

The composite board according to the present invention contains the above-mentioned cellulosic fibers in an amount of 15 to 80% by weight, preferably 30 to 60% by weight, and an inorganic filler in an amount of 5 to 40% by weight, preferably 2%.
0-40% by weight and thermosetting resin 10-45% by weight,
It is preferably produced by adjusting and compounding each in the range of 20 to 40% by weight. If the blending amount of the cellulosic fiber is less than 15% by weight or exceeds 80% by weight, it becomes difficult to secure the target workability or strength. If the content of the inorganic filler is less than 5% by weight, the workability-improving effect is insufficient, and if it exceeds 40% by weight, the strength is deteriorated, which is not preferable. Further, the blending amount of the thermosetting resin is 10
If it is less than wt%, it is difficult to secure the target strength and workability. On the contrary, if it exceeds 45 wt%, the strength is excellent but the workability is deteriorated, which is not preferable.

Further, in the composite plate according to the present invention, since the inorganic filler is filled and / or adhered to the fiber surface in the intertwisted space of the cellulosic fiber, the fiber formed of the thermosetting resin is used. The increase in strength and hardness of the composite plate due to mutual bonding and the rigidity of the fiber itself is relaxed as compared with the composite plate of the fibers alone. As a result, workability (cuttability and nailability) comparable to that of a wood-based material is imparted, and the material can be put to practical use as a substitute material. In order to obtain such an effect, the ratio (Sf / Sp) of the total surface area Sf of the inorganic filler to the total surface area Sp of the cellulosic fiber is preferably Sf / Sp =.
It is achieved by holding at 0.05 to 10.0, more preferably 0.1 to 7.5. Ratio of total surface area (Sf / S
When p) is less than 0.05, nailing performance is improved, but burning or scorching due to friction during cutting is likely to occur. On the other hand, when Sf / Sp exceeds 10.0, it contributes to the reduction of workability, especially cutting resistance, and the cutting surface becomes smooth and no special finishing process is required, but cracks occur during nailing. And cracks easily occur.

It was also found that the Sf / Sp contributes to the balance of drainage and retention characteristics, which are important factors during the papermaking of the method of the present invention. That is, Sf
When / Sp is less than 0.05, the yield is improved due to the water retention of the cellulosic fiber itself and the outflow suppressing effect of the inorganic filler, but the drainage is lowered and the production efficiency is deteriorated. On the other hand, when Sf / Sp exceeds 10.0, the weakening of the above action of the cellulosic fiber causes
The drainage is improved but the yield is reduced.

Such a composite plate can be suitably manufactured by a method applying the following papermaking method, but the invention is not limited thereto. First, after introducing cellulosic fibers, inorganic filler and thermosetting resin into a disintegrating beater (for example, pulper, Henschel mixer) in which a large amount of water has been added in advance, disperse each component together with disaggregation of the fibers by high speed stirring. For mixing, cellulosic fiber, inorganic filler, and further mixed in a mixing tank with stirring blades if necessary.
Make a slurry of thermosetting resin and water. At this time, the slurry concentration (solid content) is appropriately adjusted according to the papermaking operation in the papermaking process described later, but generally 0.01
10 to 10% by weight. Since the method of the present invention employs such a low slurry concentration, it has an advantage that a large amount of the pulverized gypsum board waste material with a fibrous surface material can be used as compared with the conventional gypsum board manufacturing method. Further, in the case of using a relatively water-soluble large inorganic filler, for example, gypsum board crushed product, in order to avoid a decrease in the yield of the formulation due to the elution of the inorganic filler into water, saturation of the inorganic filler as a substitute for water. The use of aqueous or supersaturated aqueous solutions is recommended.

Next, a fixing agent is preferably added to and mixed with the slurry obtained in the above step, and the mixture is mixed with a desired shape, for example, a sheet by a fourdrinier or cylindrical continuous or batch papermaking machine. Paper into a sheet-shaped or thin plate-shaped wet molded body, dehydrated by filtration, decompression, pressing, etc., and dried with a drying device such as a drum dryer, a hot air ventilation dryer, a dielectric heating dryer, a far infrared dryer, a vacuum dryer, etc. It is dried to obtain an uncured curable molded body. If necessary, a crosslinkable curing agent (for example, hexamethylenetetramine or a water-soluble resol-type phenol resin), a curing accelerator, etc. may be fixed to the wet molded article produced in the papermaking step by spray impregnation. . In addition, in order to produce such a curable molded article, a mixture obtained by uniformly mixing a cellulosic fiber, an inorganic filler, and a thermosetting resin, which have been pulverized or disaggregated by an appropriate pulverizer, with a mixer in some cases. Is shaped into a mat-shaped fleece having a desired basis weight with a shaping machine such as a fleece manufacturing machine, and a desired thickness (for example, sheet shape, thin plate shape, while suppressing curing of the resin with a baking machine, a press machine, or the like). A dry method may be employed in which a curable molded body in an uncured state is obtained by adjusting the matte type).

Next, the curable molded product obtained in the above step is singly or plurally laminated and then cured by a molding machine having a heating and pressing mechanism, for example, a compression molding machine, a pultrusion molding machine, an extruder or the like. To form a composite plate (cured molded product) having a single-layer or laminated structure. Further, the cured molded body of the single layer or laminated structure, further, for example, screws, nails, bonding and fixing means such as adhesives, preferably adhesives, especially curable adhesives such as phenolic resin, urea resin, melamine resin,
It is also possible to form a composite plate (joint body) having a laminated structure in which a part or the whole surface is adhesively fixed with an epoxy resin, a urethane resin or the like.

In the slurry preparing step in the method of the present invention, various additives such as a crosslinkable curing agent, if necessary,
A curing accelerator, a sizing agent such as a water-soluble polymer, a surfactant (dispersing agent or defoaming agent), a paper-strengthening agent, and other suitable reinforcing fibers such as aramid fiber within the scope of the present invention. , Nylon fiber, polyester fiber, cured phenol fiber, carbon fiber, aluminum fiber and the like may be blended. Further, on the front and back surfaces and / or the core of the composite plate of the present invention, resin impregnated decorative papers such as melamine resin decorative paper and diallyl phthalate resin decorative paper, kraft paper, aluminum kraft paper, printed paper, etc. Paper, acrylic resin,
Plastic sheets such as vinyl chloride resin, cork sheets, wood-based thin plates such as natural wood plywood, aluminum thin plates, stainless steel thin plates, metal thin plates such as embossed metal thin plates, woven or non-woven fabric of inorganic fibers or organic fibers Etc. may be provided.

The composite plate according to the present invention thus obtained is
Since the main purpose is to substitute the wood-based material, the density is preferably 500 to 900 kg / m ³ , preferably 6
00-800 kg / m ³ , bending strength is 200 kg / cm ²
It is necessary to have the above, preferably 200 to 700 kg / cm ² , and more preferably 300 to 500 kg / cm ² . If the density is less than 500 kg / cm ^3, it is difficult to secure the target strength and workability, while if it exceeds 900 kg / cm ³ , it is too heavy and the workability deteriorates, which is not preferable. If the bending strength is less than 200 kg / cm ² , it cannot be put to practical use as a substitute material.

[0021]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. The test methods adopted in the present invention are as follows. (i) Density of composite plate: According to JIS Z-2117. (ii) Bending strength: According to JIS K-6911. (iii) Specific surface area of inorganic filler and cellulosic fiber: According to BET method. Further, the ratio of the total surface area Sf of the inorganic filler to the total surface area Sp of the cellulosic fiber (S
f / Sp) was calculated by multiplying the specific surface area value by the amount used. (iV) Machinability: Grooving was performed on the router under the following conditions. Cutting blade rotation speed: 3000 rpm, cutting speed 20 mm /
Seconds, cutting width 10 mm, cutting depth 5 mm, cutting length 200
mm. Evaluation items: Burning of the cutting surface, discoloration, and the presence or absence of defects in the cutting groove corner surface were comprehensively observed. (V) Nailability: An iron nail (corresponding to N45 of JIS A5508) having a body diameter of 2.45 mm and a length of 45 mm was hammered by hand under the following conditions. Nailed location: 5mm from the edge of the front and back
Five inside with 15mm intervals. For each side,
Three at 20 mm intervals in the center of the plate thickness. Evaluation items: Nail driving resistance (bending degree of nails), cracks between nails (front and back), cracks around nails (front and back), changes in plate thickness, etc. were comprehensively observed. (Vi) Display of evaluation: Based on the plywood used for comparison (ordinary plywood defined by the Japan Agriculture and Forestry Standard), the above-mentioned machinability and nailability were evaluated. If excellent, "◎", equivalent The case was indicated by "○", the case where it was slightly inferior, but there was no problem in practical use, was indicated by "△", and the case where it was inferior to the extent that it could not be put to practical use was indicated by "X".

Example 1 Water 4 in a Henschel mixer
kg and softwood kraft pulp (specific surface area 0.7 m ² / g)
25 g was added, and the mixture was stirred and disintegrated for 120 seconds, and then 10 g of calcium carbonate (specific surface area 1.1 m ² / g, Mohs hardness 3)
And 15 g of benzylic ether type phenol resin powder were added, and the mixture was further stirred and mixed for 60 seconds to obtain a slurry. The Sf / Sp ratio was 0.63. Subsequently, a polyacrylamide-based fixing agent was added to this slurry with stirring and mixing, and this was then standard square sheet machine made by Toyo Seiki (experimental papermaking machine, papermaking mesh 100 mesh, 250 mm ×
(200 mm), the whole amount was injected, the mixture was filtered, and suction press dehydration was performed to obtain a wet molded body. Next, this wet molded body was dried in a hot air ventilation dryer at 80 ° C. to obtain a curable molded body. Next, eight curable moldings produced in the same manner as described above were stacked and placed in a metal frame having a height of 10 mm, and this was heated and pressed at 180 ° C. for 15 minutes to obtain a composite plate.

(Example 2) A composite plate was obtained in the same manner as in Example 1 except that 10 g of talc (specific surface area 2.5 m ² / g, Mohs hardness 1) was used in place of calcium carbonate. It was The Sf / Sp ratio was 1.4.

(Example 3) In Example 1, instead of calcium carbonate, wollastonite (specific surface area 0.78 m ² /
g, Mohs hardness 4.5) A composite plate was obtained in the same manner as in Example 1 except that 10 g was used. The Sf / Sp ratio was 0.45.

Example 4 In Example 1, instead of calcium carbonate, aluminum hydroxide (specific surface area 8 m ² /
g, Mohs hardness 3) A composite plate was obtained in the same manner as in Example 1 except that 10 g was used. The Sf / Sp ratio is 4.
It was 5.

(Example 5) In Example 1, instead of calcium carbonate, ultrafine calcium carbonate (specific surface area 11.
A composite plate was obtained in the same manner as in Example 1 except that 5 m ² / g and Mohs hardness 3) 10 g were used. The Sf / Sp ratio was 6.6.

Example 6 4 kg of saturated water of gypsum dihydrate and 25 g of the softwood kraft pulp used in Example 1 were put into a Henschel mixer, stirred and disintegrated for 120 seconds, and then a fiber component derived from a paper surface material of 1.5 Add 10 g of pulverized gypsum board waste material mainly containing dihydrate gypsum (specific surface area 1.9 m ² / g, Mohs hardness 2) containing 15% by weight and 15 g of benzylic ether type phenol resin powder, and stir and mix for 60 seconds to form a slurry. Got The Sf / Sp ratio was 1.1. Subsequently, a polyacrylamide-based fixing agent was added to this slurry, and the mixture was stirred and mixed, and this was then standard square sheet machine (laboratory papermaking machine, papermaking mesh 100 mesh, 25
(0 mm × 200 mm), the whole amount was injected, filtered, and suction-pressed and dehydrated to obtain a molded product in a wet state. Next, this wet molded body was dried in a hot air ventilation dryer at 80 ° C. to obtain a curable molded body. The yield of the obtained curable molded product was 93% by weight with respect to the total amount charged, but the yield was 75% by weight when water was used instead of the gypsum dihydrate saturated water. Next, eight curable molded bodies produced in the same manner as described above were stacked and placed in a metal frame having a height of 10 mm, and then heat-press molded at a temperature of 180 ° C. for 15 minutes to obtain a composite plate.

(Example 7) In Example 6, instead of the softwood kraft pulp, recycled newspaper pulp (specific surface area 2.7
A composite plate was obtained in the same manner as in Example 6 except that 25 g of m ² / g) was used. The Sf / Sp ratio was 0.28.

Comparative Example 1 The same as Example 1 except that 17.5 g of ultrafine calcium carbonate was used in place of calcium carbonate and the amount of softwood kraft pulp used was changed to 17.5 g. To obtain a composite board. In addition,
The Sf / Sp ratio was 16.4.

(Comparative Example 2) Water 4 in a Henschel mixer
kg and 35 g of the softwood kraft pulp used in Example 1
Is added and stirred and disintegrated for 120 seconds, then 15 g of benzylic ether type phenol resin powder is added, and further 60
The mixture was stirred and mixed for 2 seconds to obtain a slurry. Subsequently, a polyacrylamide-based fixing agent was added to this slurry with stirring and mixing, and this was then standard square sheet machine manufactured by Toyo Seiki (experimental papermaking machine, papermaking mesh 100 mesh, 250 mm × 200 m).
The whole amount was poured into m), filtered, and further suction-pressed and dehydrated to obtain a wet molded body. Then, the wet molded body is
A curable molded body was obtained by drying in a hot air ventilation dryer at 0 ° C. Next, eight curable molded bodies produced in the same manner as described above were stacked and placed in a metal frame having a height of 10 mm, and then heat-press molded at a temperature of 180 ° C. for 15 minutes to obtain a composite plate.

(Comparative Example 3) In Example 6, 5 g of softwood kraft pulp, 40 g of ground gypsum board waste material,
A curable molded body was produced in the same manner as in Example 6 except that the amount of the benzylic ether type phenolic resin powder was changed to 5 g, and then 9 pieces of the curable molded body were stacked and placed in a metal frame having a height of 10 mm. Then, the composite plate was obtained by heat-press molding at a temperature of 180 ° C. for 15 minutes. The Sf / Sp ratio is 21.
It was 7.

Comparative Example 4 In Example 6, 15 g of softwood kraft pulp and 7.5 g of ground gypsum board waste material were used.
2 g of benzylic ether type phenol resin powder
A curable molded body was prepared in the same manner as in Example 6 except that the amount of the curable molded body was changed to 7.5 g. Then, 8 pieces of the curable molded body were stacked and placed in a metal frame having a height of 10 mm at a temperature of 180 ° C. 15
A composite plate was obtained by heat-press molding for minutes. In addition, Sf / Sp
The ratio was 1.4.

Next, regarding the composite plates (Examples 1 to 7 and Comparative Examples 1 to 4) obtained in the above Examples and Comparative Examples and the plywood (Comparative Example 5) used for comparison between the present invention and the control, The density, bending strength and workability (cuttability and nailability) were evaluated by the test methods described. The results are shown in Tables 1 and 2.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

As described in detail above, the composite board according to the present invention has a weight, strength, and workability comparable to those of plywood. Therefore, as a substitute material for wood-based materials, for example, members for construction civil engineering and woodworking. It can be used for parts, teaching materials, etc. Further, according to the method of the present invention, since the papermaking method with a low slurry concentration is adopted, it is possible to effectively utilize the gypsum board waste material with the fibrous surface material, which has been conventionally discarded. When a saturated or supersaturated aqueous solution of an inorganic filler is used as the papermaking water, a composite plate with stable quality can be produced with a high yield. Furthermore, it is possible to provide the advantage that the drainage and the yield, which are important factors during papermaking, can be balanced. As described above, according to the present invention, it is possible to easily provide a composite board which is a waste material of gypsum board, which is an industrial waste, and which can be practically used as a substitute material for a wood-based material, and thus is paid attention to society. It can contribute to solving the problem of waste gypsum board and protecting the natural environment by saving wood resources.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kenji Nagata 2-4-2 Daisaku Sakura, Chiba Prefecture Chichibu Onoda Central Research Institute (72) Inventor Isao Tajima 1-6 Shinmachi, Nishi-ku, Osaka-shi, Osaka No. 22 Sowa Kasei Co., Ltd. (72) Inventor Mitsugi Nagata 4 Azai Organic Materials Co., Ltd. Aichi Plant, No. 26, Niitsu, Fuso-cho, Niwa-gun, Aichi Prefecture 4 Asahi Organic Material Industry Co., Ltd. 26, Niitsu 26, Minamiyama, Fuso-cho, Gunma (72) Inventor, Toshihiko Kaneiwa Toshihiko Iwa 4 4 Asahi Organic Material Co., Ltd., Niiyama, Fuso-cho, Niwa-gun, Aichi Prefecture Aichi factory

Claims (6)

[Claims] 1. A cellulosic fiber is 15 to 80% by weight,
5-40% by weight of inorganic filler and 1% of thermosetting resin
A cured molded product obtained by heating and pressing a compounded body of 0 to 45% by weight or a bonded product thereof, and the ratio (Sf / Sp) of the total surface area Sf of the inorganic filler to the total surface area Sp of the cellulosic fiber is 0.05. A composite plate characterized by being in the range of 10.0. 2. The composite plate according to claim 1, wherein the inorganic filler has a Mohs hardness of 5 or less. 3. The composite board according to claim 1, wherein at least a part of the inorganic filler is a pulverized product of gypsum board waste material. 4. A step of preparing a slurry composed of a cellulosic fiber, an inorganic filler, a thermosetting resin, and water (here, a ratio of a total surface area Sf of the inorganic filler to a total surface area Sp of the cellulosic fiber (Sf / Sp) is 0.
05-1.0), a step of preparing a curable molded article by drying a wet molded article obtained by forming the slurry into a sheet, and heating and pressurizing the curable molded article after laminating a single or plural curable molded articles. The manufacturing method of the composite board of Claim 1 including the process of preparing a hardening molded object or its joined body. 5. The method according to claim 4, wherein the inorganic filler has a Mohs hardness of 5 or less. 6. The production method according to claim 4, wherein a crushed product of gypsum board waste material is used as at least a part of the inorganic filler.