JPH115203A - Fiberboard and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method of manufacturing a fiberboard, with which the fiberboard can be manufactured by dry process and facilities for the fiberboard can be contrived to miniaturize as compared with a wet process manufacturing method and both a facility cost and a running cost can be reduced owing to small drying load in a molding process. SOLUTION: Used papers are split by dry process. A fiberboard stock (used paper pulp), the bulk density of which is prepared to be 0.030 g/cm<3> or less, 2-15 wt.% (dry basis) of a polyisocyanate compound and 2-30 wt.% (dry basis) of a resin stock, which is prepared by pulverizing a thermoplastic resin having the melting point of 160 deg.C or lower, is heated at 160 deg.C or lower under pressure so as to obtain a formed body having a water content of 10 wt.% or less and a specific gravity of 0.6-1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiberboard and a method of manufacturing the same, and more particularly, to a method of manufacturing a fiberboard mainly using waste paper such as newsprint, magazine, and corrugated cardboard, and a fiberboard manufactured by the method.

[0002]

2. Description of the Related Art A factory,
A large amount of waste paper discharged from offices, households, etc.
In recent years, they have been reused for various purposes from the viewpoint of environmental protection and effective use of resources. As one of the recycling methods, a method of manufacturing a fiberboard (used paper board) for building materials from used paper is known.

[0003] By the way, as a method of manufacturing a fiberboard using waste paper or the like as a raw material, for example, waste paper is defibrated and crushed by a wet method to remove foreign substances, and then washed and dehydrated. There is a method in which water and chemicals such as a binder (adhesive), a water repellent, and a fixing agent are added to and mixed with the raw material, and then the fiberboard raw material is formed while being dehydrated.

However, when producing fiberboard by the above-mentioned conventional method, waste paper or papermaking waste is wet-fibrillated and crushed to form a slurry. In addition, the amount of raw material (slurry) handled increases and the equipment becomes larger. Waste liquid after separating solids (fibers) from raw material slurry and cleaning liquid after washing separated solids (fibers) are treated. In a wet fiberboard manufacturing method, a binder is usually added to the raw material slurry, but the binder is dispersed in the raw material as uniformly as possible. Since it is indispensable to obtain a fiberboard having a desired strength, a strict condition control is required in the step of adding a binder, which leads to an increase in manufacturing cost. In the molding process, it is necessary to remove water, so it takes time to mold, it is difficult to improve production efficiency, and the thickness of the fiberboard that can be manufactured is limited. There is.

Further, in order to solve such problems, a dry fiberboard is prepared by adding a polyisocyanate compound as a binder to a waste paper material or a waste paper material obtained by dry-fibrillating waste paper, and heat-molding under predetermined conditions. However, with respect to specific gravity, bending strength, peel strength, water absorption, etc., in the case of fiberboard made from waste paper, sufficient properties are obtained unlike wood boards made from wood chips. For this purpose, it is necessary to increase the blending ratio of the polyisocyanate compound, which causes a problem that the cost is increased.

[0006] The present invention solves the above-mentioned problems, and it is possible to manufacture a fiberboard in a dry process, to reduce the size of equipment as compared with a wet process, and to perform wastewater treatment. The present invention provides a method for producing a fiberboard which requires no drying, has a small drying load in the molding step, and can reduce equipment costs and running costs, and a fiberboard excellent in economic efficiency obtained from the production method. With the goal.

[0007]

Means for Solving the Problems In order to achieve the above object, the method for producing a fiberboard according to the present invention (claim 1) comprises the following steps: (a) dry defibration of waste paper to obtain a bulk density of 0.030 g / cm ^3; Waste paper raw material (defibrated fiber) adjusted as follows, (b) 2 to 15% by weight of a polyisocyanate compound (dry basis), and (c) resin raw material 2 obtained by refining a thermoplastic resin having a melting point of 160 ° C. or lower.
Fiberboard raw material containing up to 30% by weight (dry basis)
It is characterized in that it is heated and pressurized at a temperature of 160 ° C. or more to form a molded body having a water content of 10% by weight or less and a specific gravity of 0.6 to 1.0.

In the present invention, dry defibration is defined as "a waste paper is roughly crushed by a rotary blade, and then sprayed and moistened with hot water, and is pushed between two fixed blades by a rotary pin. The material to be defibrated (waste paper) is crushed by the impact of a pin, and the part is further entangled with another material to be defibrated (waste paper), and the fibers are unraveled by being rubbed together. Can be carried out by using a dry paper defibrating machine manufactured by Sumikura Industry Co., Ltd.

As in the method for producing a fiberboard according to the present invention, waste paper is subjected to dry defibration and the bulk density is adjusted to 0.030 g / cm ³ or less.
A fiberboard raw material containing 2 to 30% by weight of a resin material obtained by pulverizing the following thermoplastic resin and 2 to 15% by weight of a polyisocyanate compound is heated and pressurized at a temperature of 160 ° C. or more to obtain a water content of 10%. By using a molded article having a specific gravity of 0.6 to 1.0% by weight or less, the dry-fibrillated waste paper raw material (fibrillated fiber) is tightly entangled, and the polyisocyanate compound functions as an adhesive. Recycled resin material (defibrated fiber) by using resin material as a binder
The fibers inside can be securely bonded and bonded to each other, so that the bending strength and peel strength of the fiberboard as a product can be improved. In addition, the resin raw material added as a binder is melted and enters into the defibrated fiber, thereby reducing the water absorption and improving the water repellency.

[0010] The bending strength, which is a typical physical property of a fiberboard, is greatly affected by the specific gravity of the fiberboard, the properties of the defibrated waste paper raw material, and the types and amounts of adhesives and binders. That is, in order to improve the bending strength of the fiberboard, it is necessary to increase the contact area of the waste paper raw material (defibrated fiber) after fibrillation. In order to increase the contact area, it is necessary to increase the proportion of fine fibers of the defibrated fiber composed of the skeleton and the fine hair derived from the skeleton, and for that purpose, it is necessary to sufficiently defibrate the waste paper. Will be needed.
Further, it is difficult to directly measure the degree of fibrillation (the ratio of fine hair) of the used paper raw material. However, there is a correlation between the ratio of fine hairs in the fibrillated fiber and the bulk density. It is known that the more it is performed, the lower the bulk density of the defibrated fiber. Table 1 shows the relationship between the type of waste paper material and the bulk density of the defibrated fiber (defibrated material) after defibration.

[0011]

[Table 1]

As shown in Table 1, the OA paper and the coated book had a bulk density of the defibrated fiber (defibrated material) of 0.03.
Although beyond the 0g / cm ^3, magazine (comic books), newspaper,
Further, it is understood that the bulk density of the defibrated fiber (defibrated material) becomes 0.030 g / cm ³ or less, that is, the corrugated cardboard can be used as a raw material for the fiberboard production method of the present invention.

In the method of manufacturing a fiberboard according to the present invention, a sufficiently defibrated raw paper material (fibrillated fiber) having a bulk density of 0.030 g / cm ³ or less is used. It is possible to increase the contact area of the waste paper raw material (defibrated fiber) and improve the bending strength of the fiberboard product. In the present invention, the bulk density of the waste paper raw material obtained by dry-fibrillation of waste paper is a value obtained by measuring the waste paper raw material obtained by naturally dropping a defibrated waste paper raw material through a 10-mesh sieve.

Further, the contact portion (the portion where the fibers are in contact with each other) of the waste paper raw material after defibration is bonded by an adhesive (polyisocyanate compound),
The strength of the fiberboard is improved. In addition, by increasing the amount of the adhesive added, it is possible to increase the bonding area, and it is possible to further improve the strength of the fiberboard. In the present invention, the content of the polyisocyanate compound is set to 2 to 15% by weight. When the content is less than 2% by weight, a sufficient adhesive effect cannot be obtained. If it exceeds, the effect of improving the strength becomes insignificant, which unnecessarily increases the cost.

[0015] When the specific gravity of the fiberboard as a product is increased, the fibers are pressed strongly against each other, which leads to an increase in the contact area and the bonding area, thereby increasing the strength of the product.

In the present invention, the resin raw material obtained by refining a thermoplastic resin having a melting point of 160 ° C. or less is a polyolefin-based thermoplastic resin such as polyethylene or polypropylene; a polystyrene resin; a polyvinyl chloride resin; This is a concept that refers to raw materials that are made by cutting or pulverizing various resins and making them fine.There is no special restriction on the specific shape and dimensions, but increasing the surface area by making them as fine as possible will improve the strength of products. Desirable from the point of view of.

In addition, polyolefin-based thermoplastic resins such as polyethylene and polypropylene, polystyrene resins,
Resin raw materials such as polyvinyl chloride resin and polyvinyl acetate do not have the same adhesive strength as polyisocyanate compounds (adhesives), but they are inexpensive, so the amount of expensive polyisocyanate compounds can be reduced. Become. In other words, the resin raw material does not have the adhesive property of the polyisocyanate compound, but has no polarity, and has good dispersibility, particularly when the powder is spherical, and is uniformly filled in the fiberboard to exert a stress dispersion effect. It exerts the function of improving bending strength and peel strength. In the step of molding by heating and pressurizing, the resin melts and enters the raw paper raw material fiber, exhibits a function as a binder, and also has a function of reducing the water absorption of the fiberboard as described above.

It is also possible to use waste as a resin raw material. In this case, there is an advantage that the waste can be circulated for environmental protection and effective use of resources.

In the present invention, the content of the thermoplastic resin is set to 2 to 30% by weight because the content is 2% by weight.
If it is less than 3, the process becomes complicated for the effect.
If the content exceeds 0% by weight, for example, molding by hot pressing or the like becomes difficult.

The melting point of the thermoplastic resin is 160 ° C.
The reason for using the following is that in the case where a material having a melting point of 160 ° C. or more is used, in a step of heating and pressing at a temperature of 160 ° C. or less, the thermoplastic resin does not melt and functions as a binder. It cannot be demonstrated.

The reason why the temperature at the time of heating and pressurizing the fiberboard raw material is set to 160 ° C. or higher is to consider the melting temperature of the thermoplastic resin as the adhesive as the binder and the curing temperature of the polyisocyanate compound. In addition, it is possible to shorten the time of heating and pressurizing, thereby improving productivity.

The reason why the moisture content of the molded article (fiberboard) after molding by heating and pressurizing is set to 10% by weight or less is that the moisture content of the molded article is reduced to the fiberboard product. In order to prevent deformation after molding.

The specific gravity of the molded product (fiber board) is set to 0.6 to
When the specific gravity of the molded body is less than 0.6, it is difficult to stably secure product quality such as bending strength, and when it exceeds 1.0, the product weight is large. This makes handling difficult. As described above, when the specific gravity of the fiberboard as the product is increased, the fibers are strongly pressed against each other, the contact area and the bonding area are increased, and the bending strength of the product is increased as described above.

In the present invention, the polyisocyanate compound means a known compound having two or more isocyanate groups in a molecule. Examples of such a polyisocyanate compound include, for example, aliphatic polyisocyanates such as diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and cyclohexane diisocyanate, alicyclic polyisocyanates, aromatic polyisocyanates, and isomers of the polyisocyanates. An example is a body. These polyisocyanates can also be mixed with water and emulsified before use.

Further, the present method for producing a fiber plate (claim 2), the fiber plate, bending strength 180 kgf / cm ² or more, so as to satisfy the peel strength 3.0 kgf / cm ² or more requirements,
It is characterized in that each of the above conditions is selected. In the method for producing a fiberboard of the present invention, the bending strength is usually 180 kgf / cm without sacrificing other characteristics by selecting predetermined conditions within the ranges of the above conditions.
² or more and a peel strength of 3.0 kgf / cm ² or more can be satisfied.

Further, in the method for producing a fiberboard according to the present invention (claim 3), the waste paper raw material may be at least one of (a) a newspaper, (b) a comic book, a magazine such as a weekly magazine, and (c) a cardboard. In addition, the content of the filler is mainly 10% by weight or less of waste paper on a dry basis. A water content of at least one of newspaper, magazine, and corrugated cardboard and having a filler content of 10% by weight or less on a dry basis is used.
By weight percent or less, specific gravity of 0.6 to 1.0, it is possible to obtain a fiber board having high flexural strength and peel strength, low water absorption and excellent physical properties.

In the case of copy paper or coated paper containing a large amount of filler such as calcium carbonate, the fiber is hindered by the filler and is not easily loosened, and it is difficult to increase the proportion of fine hair in the defibrated waste paper raw material. Therefore, it is not suitable for use as waste paper material in the present invention. On the other hand, newspapers, magazines (cartoon books), cardboard, and the like, which have a small amount of filler, are suitable as used paper raw materials of the present invention.

Further, the method for producing a fiberboard according to the present invention (claim 4) is characterized in that in the step of dry-fibrillating the used paper, used paper having a water content of 20% by weight or less is used. By using waste paper having a water content of 20% by weight or less in the process of dry-fibrillating waste paper, the drying step becomes unnecessary and the manufacturing process can be simplified.

Further, the method of manufacturing a fiberboard according to the present invention (claim 5) is characterized in that the thermoplastic resin is a polyolefin-based thermoplastic resin. Polyolefin-based thermoplastic resins such as polyethylene do not generate harmful gases when burned, and by using this polyolefin-based thermoplastic resin, the functions required as a binder can be achieved without sacrificing safety. It is possible to do it.

Further, in the method for producing a fiberboard according to the present invention (claim 6), the fiberboard raw material containing the waste paper raw material, the polyisocyanate compound, and the resin raw material is heated to 160 ° C.
Before heating and pressurizing at the above-mentioned temperatures, a pre-press is performed at a pressure of 15 kgf / cm ² or more. Before heating and pressing the fiberboard raw material at a temperature of 160 ° C or higher,
Pre-pressing at a pressure of 15 kgf / cm ² or more allows waste paper raw material (fibrillated fiber) to constitute the fiberboard raw material
Are entangled with each other in advance, and the raw paper material (defibrated fiber) is easily bonded and bonded by the polyisocyanate compound (adhesive) and the resin raw material (binder), so that the present invention can be further effectively demonstrated. The reason why the pressure of the preliminary press is set to 15 kgf / cm ² or more is that by setting the pressure to 15 kgf / cm ² or more, a strength suitable for conveyance to a post-process is obtained and the forming process by hot pressing or the like is performed. It can be compressed to the desired thickness to serve.

Further, in the method for producing a fiberboard according to the present invention (claim 7), when the waste paper is dry-fibrillated, when the moisture content of the waste paper is less than 10% by weight, the moisture content of the waste paper raw material after the fibrillation is reduced. 10
It is characterized in that water is sprayed so as to be １５15% by weight. If the water content of the waste paper is less than 10% by weight during the dry defibration, the temperature may rise to ignite the fine paper powder generated at the time of the defibration. By spraying water so as to have a concentration of 10 to 15% by weight, it is possible to prevent an increase in temperature during dry defibration and prevent ignition.

Further, the fiberboard of the present invention (claim 8) is characterized in that (a)
Waste paper raw material (fibrillated fiber) whose dry density is adjusted to 0.030 g / cm ³ or less by dry defibration of waste paper, (b) 2 to 15% by weight of a polyisocyanate compound (dry basis),
(c) A fiberboard raw material containing 2 to 30% by weight (dry basis) of a resin raw material obtained by refining a thermoplastic resin having a melting point of 160 ° C. or less, is formed by heating and pressing, and has a water content of It is characterized by being not more than 10% by weight and having a specific gravity of 0.6 to 1.0.

Dry defibration, the bulk density is 0.030 g / cm
^A fiberboard raw material containing a predetermined ratio of a waste paper raw material adjusted to ³ or less, a polyisocyanate compound, and a resin raw material obtained by refining a thermoplastic resin at a predetermined ratio, is formed by heating and pressurizing. Weight% or less, specific gravity 0.6 ~
In the fiberboard of 1.0, the waste paper raw material is tightly entangled, and the polyisocyanate compound functions as an adhesive, and the resin raw material functions as a binder. As a result, excellent properties are realized with respect to bending strength, peel strength, water repellency (low water absorption), and the like.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be shown and the features thereof will be described in more detail. FIG. 1 is a flow sheet showing a method for manufacturing a fiberboard (waste paper board) according to an embodiment of the present invention.

The method for manufacturing the fiberboard of this embodiment is shown in FIG.
As shown in the following, the main steps are a pulverizing step A for coarsely pulverizing waste paper raw material, a water spraying step B for spraying water on the coarsely pulverized waste paper raw material as necessary, and a coarsely pulverized waste paper raw material. A dry defibration step C for dry defibration, an adhesive addition step D for adding a polyisocyanate compound as an adhesive, and a resin material addition step E for adding a resin material obtained by miniaturizing a thermoplastic resin having a melting point of 160 ° C. or lower. A laminating step F of laminating (spreading) a waste paper raw material (fiberboard raw material) to which a resin raw material and a polyisocyanate compound are added to a predetermined shape and thickness; A pre-pressing step G for pressing, a forming step (hot pressing step) H in which the pre-pressed fiberboard raw material is pressurized while being heated to a predetermined temperature and formed, and a formed formed body is cooled. Cooling and humidity control process I carry out the moisture adjustment to
And a curing step J for curing the molded article, and a product finishing step K for finishing the molded article to a final product (fiberboard).

The pulverizing step A is a step of coarsely pulverizing a used paper raw material such as a newspaper, a magazine, a corrugated cardboard or the like until it becomes a shape that can be supplied to a dry defibrating machine. In addition, when coarsely-pulverized waste paper raw material is supplied, pulverization may not be necessary in some cases.

In the water spraying step B, when the water content of the used paper raw material is less than 10% by weight, in the dry defibration step C, the temperature may rise and the paper powder generated during the defibration may be ignited. The water content of the waste paper raw material after fibrillation is 10 to 1
This is a step of spraying water at a ratio of 5% by weight, so that the waste paper material is not ignited due to an increase in temperature during dry defibration. However, when the waste paper raw material has a high water content, it may not be necessary to spray water.

The dry defibration process C is a process for dry defibration of a used paper material in which the content of the resin material is adjusted. In this process, the used paper material and the resin material are uniformly mixed.
In this dry defibration step C, the moisture in the waste paper raw material to be defibrated is removed to some extent by the air.

The adhesive addition step D is a step of adding and mixing a polyisocyanate compound as an adhesive. Here, diphenylmethane diisocyanate (MDI) was used as the polyisocyanate.

The resin raw material adding step E is a step of adding a resin raw material obtained by refining a thermoplastic resin having a melting point of 160 ° C. or less as a binder, and the waste paper raw material contains a necessary amount of the thermoplastic resin. May be omitted.
When the used paper material contains a necessary amount of the thermoplastic resin to some extent, the resin material obtained by miniaturizing the thermoplastic resin in such a ratio that the total content becomes 2 to 30% by weight (dry basis). Is added. In this embodiment, the polyethylene resin is finely divided (average particle diameter of 100 to 100).
0 μm) was used as a resin raw material.

Further, the laminating step F is a step of laminating (spreading) waste paper raw material (fiberboard raw material) to which a resin raw material and a polyisocyanate compound are added to a predetermined shape and thickness.

The pre-pressing step G is performed in a predetermined shape,
This is a step of preliminarily pressing the fiberboard raw material laminated to a thickness, and the pressing is performed at a pressure of 15 kgf / cm ² or more.

The forming step (hot pressing step) H is a step of pressing the pre-pressed fiberboard raw material while heating it to a predetermined temperature to form the resin raw material (thermoplastic resin). Melts to exhibit a function as a binder, and the polyisocyanate compound cures to exhibit a function as an adhesive.

The cooling / humidifying step I is a step of cooling the molded body formed in the molding step H and adjusting the water content. In this step, the resin raw material (thermoplastic resin) is cured, The body is fixed in a predetermined shape.

The curing step J is a step of curing the formed body, and the product finishing step K is a step of cutting and trimming the formed body to finish it into a final product (fiberboard) having a predetermined size.

Next, a method of manufacturing a fiberboard from a comic book will be described. First, in the crushing step A, a comic book is crushed. Next, when the water content of the waste paper raw material is less than 10% by weight, in the water spraying step B, water is sprayed at a rate such that the water content of the waste paper raw material after dry defibration becomes 10 to 15% by weight. .

Then, in the dry defibration step C, the comic book in which the content of the resin raw material is adjusted is placed at a bulk density of 0.03.
Dry defibration until it is 0 g / cm ³ or less (for example, 0.022 g / cm ³ ). Then, in the adhesive addition step D, a polyisocyanate compound (MDI) is added so as to have a ratio of 2 to 15% by weight (dry basis).

In the resin material adding step E, a resin material (here, a spherical polyethylene resin) obtained by refining a thermoplastic resin having a melting point of 160 ° C. or less is used as a binder.
-30% by weight (dry basis).

Next, in the laminating step F, the waste paper raw material (fiberboard raw material) to which the resin raw material and the polyisocyanate compound are added is laminated into a plate having a predetermined shape and thickness. Pre-press at a pressure of at least / cm ² .

Then, in the forming step H, the pre-pressed fiberboard raw material is pressurized while being heated to a predetermined temperature of 160 ° C. or less, and is formed.

Thereafter, in the cooling / humidity controlling step I, the molded body is cooled and water content is adjusted.

Thereafter, the formed body is subjected to a curing step J and a product finishing step K to be finished into a final product (fiberboard).

In the above embodiment, a comic book (used paper)
Waste paper (fibrillated fiber) whose bulk density has been adjusted to 0.022 g / cm ³ , a polyisocyanate compound of 2 to 15% by weight, and a resin obtained by refining a thermoplastic resin having a melting point of 160 ° C. or lower. The fiberboard raw material containing 2 to 30% by weight of the raw material is heated and pressed at a temperature of 160 ° C. or more,
Since the molded body has a water content of 10% by weight or less and a specific gravity of 0.6 to 1.0, the dry-fibrillated waste paper material (fibrillated fiber) is tightly entangled and the polyisocyanate compound is bonded. The resin material functions as a binder, and the fibers in the waste paper material (defibrated fibers) are securely bonded and bonded together.
The bending strength and peel strength of the fiberboard as a product can be improved. Further, since the resin raw material added as a binder is melted and enters into the defibrated fiber, the water absorption is reduced and the water repellency is improved.

A characteristic test was performed on the fiberboard manufactured under the conditions of the above embodiment. As a result, for example, the polyisocyanate compound addition amount (MDI) was 7.
0% by weight (dry basis), resin material (polyethylene resin)
Addition amount 2 to 30% by weight (dry basis), specific gravity 0.6 to 1.
0, bending strength 180k in the range of water content 10% by weight or less
It was confirmed that the requirement of gf / cm ² or more and the peel strength of 3.0 kgf / cm ² or more was satisfied.

FIG. 2 shows the relationship between the specific gravity of the fiberboard and the bending strength, and FIG. 3 shows the relationship between the amount of the resin material (polyethylene resin) added and the peel strength. From FIG. 2, it can be seen that the bending strength is improved when the specific gravity of the fiberboard is increased, and that the peel strength is improved when the amount of added polyethylene is increased from FIG.

Further, Table 2 shows that a comic book (used paper) was dry-fibrillated, and a polyisocyanate compound (M) was added to a used paper raw material (fibrillated fiber) whose bulk density was adjusted to 0.022 g / cm ^3.
DI) A fiberboard material to which 7% by weight and 5% by weight of resin material (polyethylene resin) are added is manually put into a molding box, prepressed at 15 kg / cm ² , and then molded at a temperature of 160 ° C. or less. 3 shows the physical properties of the fiberboard obtained. The JIS standard reference values are also shown for reference.

[0057]

[Table 2]

In the above embodiment, as the thermoplastic resin,
Since polyethylene (polyolefin-based thermoplastic resin) is used, no harmful gas is generated at the time of combustion, and the required action as a binder can be performed while ensuring safety.

In the present invention, since a polyisocyanate compound is used as the adhesive, sufficient adhesive strength is secured without causing generation of harmful substances such as formalin, and mechanical strength, water repellency, etc. Characteristics can be improved.

In the above-described embodiment, the case where a comic book is used as a used paper material has been described.
Corrugated cardboard or the like can be used as a raw material for used paper, and in this case, the same effect as in the above embodiment can be obtained.

The present invention is not limited to the above embodiment in other respects, and various applications and modifications can be made within the scope of the present invention.

[0062]

As described above, in the method for producing a fiberboard according to the present invention, as in the method for producing a fiberboard, waste paper is dry-fibrillated and the bulk density is adjusted to 0.030 g / cm ³ or less. A fiberboard raw material containing waste paper raw material (defibrated fiber), 2 to 15% by weight of a polyisocyanate compound, and 2 to 30% by weight of a resin raw material obtained by pulverizing a thermoplastic resin having a melting point of 160 ° C. or less is used. Heat and pressurize at the temperature of
Since the molded body has a water content of 10% by weight or less and a specific gravity of 0.6 to 1.0, the dry defibrated raw paper material (defibrated fiber) is tightly entangled and the polyisocyanate compound is bonded. The resin material functions as a binder, and the fibers in the waste paper material (defibrated fibers) are securely bonded and bonded together.
The bending strength and peel strength of the fiberboard as a product can be improved. Further, the resin raw material added as a binder is melted and enters into the defibrated fiber, thereby reducing the water absorption and improving the water repellency.

Further, as in the case of the second aspect of the present invention, by selecting predetermined conditions within the range of each condition of the present invention, the bending strength can be increased to 180 k without sacrificing other characteristics.
The requirements of gf / cm ² or more and peel strength of 3.0 kgf / cm ² or more can be satisfied, and a fiberboard having characteristics practically required can be efficiently produced.

Further, as in the case of claim 3 of the present application, at least one of newspaper, magazine, and cardboard,
In addition, by using a waste paper raw material mainly composed of waste paper having a filler content of 10% by weight or less on a dry basis, a water content of 1% is obtained.
A fiberboard having 0% by weight or less, specific gravity of 0.6 to 1.0, high flexural strength and peel strength, low water absorption and excellent physical properties can be obtained.

Further, as in the case of claim 4 of the present application, in the process of dry-fibrillating waste paper, by using waste paper having a water content of 20% by weight or less, the drying step becomes unnecessary, and the manufacturing process is simplified. Can be

Further, by using a polyolefin-based thermoplastic resin such as polyethylene as the thermoplastic resin as in the case of claim 5 of the present application, no harmful gas is generated at the time of combustion, and safety is improved. The required action as a binder can be performed while securing the same.

Further, as in the case of claim 6 of the present application, the fiberboard raw material is pre-pressed at a pressure of 15 kgf / cm ² or more before heating and pressurizing at a temperature of 160 ° C. or more, whereby the fiber The waste paper raw material (defibrated fiber) constituting the board raw material is entangled with each other in advance, and the waste paper raw material (defibrated fiber) is easily bonded and bonded by the polyisocyanate compound (adhesive) and the resin raw material (binder), The present invention can be made more effective.

Further, as in the case of claim 7 of the present application, when the water content of the waste paper is less than 10% by weight during dry defibration,
By spraying water so that the water content of the waste paper raw material after dry defibration becomes 10 to 15% by weight, the temperature rise during dry defibration is prevented, ignition is prevented, and safety is improved. Can be done.

The fiberboard of the present invention is dry-defibrated,
By heating and pressurizing a fiberboard raw material containing a predetermined ratio of a wastepaper raw material having a bulk density adjusted to 0.030 g / cm ³ or less, a polyisocyanate compound, and a resin raw material obtained by making a thermoplastic resin finer, The formed water content is 1
0% by weight or less, a fiberboard having a specific gravity of 0.6 to 1.0,
The waste paper raw materials are tightly entangled, and the polyisocyanate compound functions as an adhesive, while the resin raw materials function as a binder. Excellent characteristics are realized with respect to water repellency (low water absorption) and the like.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a method for manufacturing a fiberboard according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between specific gravity and bending strength of a fiberboard manufactured by the method for manufacturing a fiberboard according to one embodiment of the present invention.

FIG. 3 is a diagram showing the relationship between the amount of resin material (polyethylene resin) added to a fiberboard manufactured by the method for manufacturing a fiberboard according to one embodiment of the present invention and the peel strength.

[Explanation of symbols]

 A crushing process B water spraying process C dry defibration process D adhesive adding process E resin raw material adding process F laminating process G pre-pressing process H forming process (hot pressing process) I cooling / humidifying process J curing process K product finishing process

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Norihiro Murayama, Inventor 2-1-2, Kuse-Terashima, Amagasaki City, Hyogo Prefecture Inside Kimura Kakoki Co., Ltd. Kimura Kakoki Co., Ltd.

Claims (8)

[Claims] 1. (a) Dry defibration of waste paper to a bulk density of 0.0
Waste paper raw material (defibrated fiber) adjusted to 30 g / cm ³ or less, and (b) 2 to 15% by weight of a polyisocyanate compound
A fiberboard raw material containing (dry basis) and (c) 2 to 30% by weight (dry basis) of a resin material obtained by refining a thermoplastic resin having a melting point of 160 ° C. or less is heated at a temperature of 160 ° C. or more. -A method for producing a fiberboard, which comprises applying a pressure to a molded body having a water content of 10% by weight or less and a specific gravity of 0.6 to 1.0. 2. A fiber plate, bending strength 180 kgf / cm ² or more, so as to satisfy the peel strength 3.0 kgf / cm ² or more requirements, claim 1, characterized by selecting the respective conditions
The method for producing a fiberboard according to the above. 3. The waste paper raw material is at least one of (a) a newspaper, (b) a comic book, a magazine such as a weekly magazine, and (c) a cardboard, and the filler content is 10% by weight on a dry basis. 3. A method for producing a fiberboard according to claim 1, wherein the main component is waste paper of not more than%. 4. The method for producing a fiberboard according to claim 1, wherein in the step of dry-fibrillating the used paper, used paper having a water content of 20% by weight or less is used. 5. The method according to claim 1, wherein said thermoplastic resin is a polyolefin-based thermoplastic resin. 6. A fiberboard raw material containing the waste paper raw material, the polyisocyanate compound, and the resin raw material,
Before heating and pressurizing at a temperature of 60 ° C or more, 15kgf / cm
6. The method for producing a fiberboard according to claim 1, wherein the preliminary press is performed at ^two or more pressures. 7. When dry-fibrillating waste paper, when the water content of the waste paper is less than 10% by weight, water is sprayed so that the water content of the waste paper material after fibrillation becomes 10 to 15% by weight. The method for producing a fiberboard according to claim 1, 2, 3, 4, 5, or 6. 8. (a) Dry defibration of waste paper to a bulk density of 0.0
Waste paper raw material (defibrated fiber) adjusted to 30 g / cm ³ or less, and (b) 2 to 15% by weight of a polyisocyanate compound
A fiberboard raw material containing (dry basis) and (c) 2 to 30% by weight (dry basis) of a resin material obtained by refining a thermoplastic resin having a melting point of 160 ° C. or lower is formed by heating and pressing. And a water content of 10% by weight or less and a specific gravity of 0.6 to
A fiberboard, characterized by being 1.0.