JPH07121523B2 - Fiberboard manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a method for producing a fiber board, and more particularly to a humidity control method or a cooling and humidity control method after heat-press molding a fiber mat using a hot press machine.

[0002]

2. Description of the Related Art Wet methods and dry methods are known as methods for producing fiberboard. In either method, the paper mat formed or formed is generally heat-pressed and molded using a hot press machine.

In the dry method, since the formed fiber mat itself has a relatively low water content and is further dried by heating in a hot press machine and has a high temperature, the fiber board is immediately heated and pressed. Cannot be deposited. Therefore, the heated and pressure-molded fiberboard is cooled by natural heat dissipation while being supported while being separated from each other by a cooling device of an elevator type, a wicket type, or the like, or by cooling air blowing by a cooling fan.

In the wet method, the water content of the fiber mat itself produced is considerably high, but it is dried by heating in a hot press machine, and the water resistance of the fiber board is improved to improve the mechanical strength such as bending strength. Since the temperature in the heat treatment and the oil impregnation treatment performed for this purpose is also high, the fiberboard is highly dried and at a high temperature, so that the fiberboard cannot be deposited immediately after those treatments. Therefore, cooling must be performed in the same manner as in the dry method.

After cooling, the fiberboard obtained by any of the methods is in a dry state much lower than the equilibrium water content with the atmosphere. When such a fiber board is cut and cut as it is, moisture absorption thereafter increases the length and thickness, and causes unevenness in dimensions, warpage, deviation, and distortion. Therefore, it is also a common practice to condition the fiberboard after cooling.

Since it is necessary to control the humidity evenly, the humidity control is performed while the fiberboard is conveyed in a high humidity control chamber while being supported by a conveyor such as an elevator type or a wicket type so as to be separated from each other.

[0007]

The humidity control or cooling and humidity control in the prior art requires that the fiberboards be supported separately from each other, that the fiberboards have a low thermal conductivity, and that the moisture content inside the fiberboards is low. Due to the slow transfer, etc., a large amount of factory space is required, it takes time, and equipment costs and power costs are required for the ventilation of the cooling fan and the adjustment of humid air.

When an adhesive containing formalin is used in the production of fiberboard, a formalin odor remains in the product,
Not only is it uncomfortable, but there are hygiene problems,
It is required to reduce the residual amount of formalin below the standard value. This formalin removal process also requires a factory space and time, which lowers the production efficiency. This problem can be solved by using an adhesive that does not contain formalin, but it is not preferable because the cost is generally high.

[0009]

SUMMARY OF THE INVENTION The present invention was devised after intensive efforts to solve the above-mentioned problems of the prior art. After the fiber mat is heated and pressed by using a hot press machine, In the method of manufacturing a fiberboard for controlling humidity,
The humidity control of the fiber board is performed by spraying or applying water containing a formalin catcher agent on one or both surfaces of the fiber board.

The spraying or application of water containing the formalin catcher agent is preferably carried out after the heat and pressure molding of the fiber mat while the fiber board is at a high temperature.

[0011]

Example: A uniform mixture of wood fibers obtained by defibrating wood chips with a refiner, an adhesive, and a sizing agent is formed into a fiber mat using a forming device, prepressed, and then hot pressed by a hot press device. . The temperature of the fiberboard after molding varies depending on the adhesive used, the thickness of the fiberboard to be produced, the specific gravity, etc., but the surface temperature is generally 1
Around 50 ° C, the internal temperature is about 100 to 140 ° C.

Water is sprayed or applied to one or both surfaces of the fiberboard after molding while maintaining a high temperature. The spraying method may be spraying or roll coating,
As the roll, a sponge roll, a cloth-rolling roll, a cloth roll, or the like can be used.

In the case of spraying, the smaller the liquid droplets, the more uniform cooling and humidity control can be performed, but the cooling time becomes longer and the space required also tends to become large, and there is a tendency to be chased upward due to the generation of steam. There is. Therefore, spraying may be done from bottom to top. When the liquid droplets are large, it is better to jet strongly so that the liquid droplets are broken by the collision force, and it is necessary to vibrate the jetting direction to perform uniform cooling and humidity control.

By spraying or applying water while the plate temperature is high, the water is instantly vaporized, and at that time, the heat of vaporization is taken from the fiber board, so that the cooling is performed rapidly. In addition, the steam generated at that time is useful for humidity control. The amount of water sprayed is appropriately determined according to the plate temperature.

The spraying or application of water may be carried out on only one side of the fiber board, but it is more preferred that it is carried out on both sides. However, when the cooling proceeds relatively rapidly, by performing it only on one surface and immediately depositing it with the plate surface horizontal, substantially the same result as spraying or applying water on both surfaces can be obtained. To be

Cooling and humidity adjustment by spraying or applying water may be carried out continuously or intermittently in two or more times. For example, while the fiberboard is at a high temperature, the first spraying or coating is carried out, carried into a conventional cooling device, and after cooling, a second spraying or coating is carried out. In that case, the first spraying or application may be performed on one surface of the fiberboard, and the second spraying or application may be performed on the other surface.

Further, in general, during the heating and pressing, the fiber mat is heated from its surface at the same time as the compression, so that the water in the layer close to the surface evaporates and evaporates. Conversely, it shifts to the core part. Furthermore, the water vapor on the surface side of the fiberboard is rapidly released during decompression. Therefore, in the fibrous board after heat-press molding, 5% between the surface layer portion and the core portion
The above difference in water content is likely to occur. Cutting such a fiberboard tends to cause warpage and deviation. Therefore, it is preferable to adjust the difference in water content between the surface layer portion and the core portion of the fiber board to 5% or less by the cooling and humidity control steps. However,
Immediately after the cooling and humidity control steps, it is not necessary to control the humidity so as to show such a difference in water content, and the humidity control can be advanced during the deposition. In this case, the humidity control can be promoted by simply depositing the fibrous plates without supporting them separately from each other, so that the required space in the factory and the residence time in the cooling device or the humidity control chamber are significantly reduced. To be done.

Formalin catcher agents such as urea, ammonium acetate, ammonium sulfite, sodium sulfite, thiosemicarbazide, ethylenediamine, and natural protein are added to the water sprayed or applied on one or both sides of the fiber board in advance. As a result, free formalin remaining in the fiberboard produced by using a formalin-based adhesive such as urea resin, melamine resin, urea-melamine resin is collected. Regarding the formalin collection effect, it is more efficient to spray or apply water containing the formalin catcher agent while the fiberboard temperature is high, and the effect of preventing pollution of air in the factory is also high.

[0019]

EFFECTS OF THE INVENTION According to the present invention, since water can be sprayed or applied to one or both sides of a fiber board after cooling and then deposited immediately, it is possible to save space and time in the humidity control line, and to improve production efficiency. Is improved.

When water is sprayed or applied to one or both surfaces of the fiber board while the fiber board is at a high temperature, the space and time of the cooling line can be saved.

When cooling and humidity control are performed by spraying or applying water, it is possible to save space in both lines and save time.

Production efficiency can be improved only by providing a spraying device or a coating device in the existing equipment.

A fiber board having a uniform water content can be efficiently produced.

Since the formalin catcher agent is added to the water sprayed or applied on the fiber board, the free formalin remaining in the fiber board produced by using the formalin-based adhesive can be efficiently collected.

Claims (2)

[Claims] 1. A method for producing a fiber board in which a fiber mat is heat-pressed using a hot press machine and then subjected to humidity control. In the method, the humidity control of the fiber board is carried out on one or both sides of the fiber board. A method for producing a fiber board, which is carried out by spraying or applying water to which is added. 2. The fiber board according to claim 1, wherein the water containing the formalin catcher agent is sprayed or applied while the fiber board is at a high temperature after the heat-press molding of the fiber mat. Production method.