JP2001030212A - Manufacture of medium-density fiberboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to easily confirm the presence of dispersion irregularities of an adhesive and easily check the deterioration of peel strength of a medium-density fiberboard by blending wood fibers with the adhesive mixed with a coloring agent and thermally pressing the wood fibers, when the medium- density fiberboard to be used as a building material is manufactured. SOLUTION: When a medium-density fiberboard is manufactured, first wood chips are sieved and classified, digested and fibrillated into wood fibers. Next an adhesive containing a coloring agent is applied to the wood fibers, which are, in turn, blended with an adhesive containing the coloring agent. After heating and drying these wood fibers, an adhesive mixed with the coloring agent is applied to the wood fibers. The wood fibers obtained as described are classified to remove a foreign substance and are sent under pressure to be molded into mats in a forming process. Further, the molded mats are temporarily pressed using a roll and are thermally pressed into finally compressed forms. After that, the pressed moldings are once stacked to be surface-finished using a sander and then are cut to a desired length to obtain the medium-density fiberboard.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a medium density fiberboard which can be used as a building material.

[0002]

2. Description of the Related Art Generally, medium density fiberboard (MDF: medi)
um density fiberboards)
It is manufactured by blending an adhesive with wood fibers obtained by defibrating wood chips and hot-pressing them.

[0003]

However, when the adhesive is not uniformly distributed in such a medium-density fiberboard, the medium-density fiberboard is peeled off at a portion where the adhesive is insufficient. May have occurred. For this reason, it is necessary to inspect the peel strength of the medium-density fiberboard, but it has been difficult to non-destructively inspect the peel strength.

[0004] The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for manufacturing a medium-density fiberboard which can easily identify uneven distribution of the adhesive in the medium-density fiberboard. It is assumed that.

[0005]

According to a first aspect of the present invention, there is provided a method for manufacturing a medium-density fiberboard, wherein an adhesive mixed with a coloring agent is blended into a wood fiber, and this is hot-pressed. It is assumed that.

According to a second aspect of the present invention, there is provided a method for manufacturing a medium-density fiberboard, wherein a dye or a pigment is used as a coloring agent in addition to the first aspect.

[0007]

Embodiments of the present invention will be described below.

As the adhesive, a melamine resin-based or urethane resin-based adhesive can be used. In the present invention, a coloring agent is mixed into the adhesive. As the coloring agent, dyes, pigments and the like can be used,
For example, titanium oxide can be used. Here, when a melamine resin-based adhesive is used, an aqueous colorant, a pigment, a powder, or the like can be used as the colorant.However, when a urethane resin-based adhesive is used, the urethane resin is used. Aqueous colorants cannot be used because the isocyanates of this type react with water.

In mixing a colorant into the adhesive, the colorant is uniformly dispersed in the adhesive.
Especially when using a pigment as a colorant, there may be a problem in dispersibility, so after mixing the pigment in the colorant,
It is preferable that the adhesive mixed with the pigment is continuously stirred until it is mixed with the wood chips.

One example of a process for manufacturing a medium density fiberboard will be described with reference to FIG.

First, wood chips are sieved to classify, digested and defibrated to obtain wood fibers. In this wood fiber,
The adhesive mixed with the coloring agent is applied by a method such as spray coating to mix the wood fiber with the adhesive mixed with the coloring agent. At this time, if necessary, wax is applied simultaneously. After drying this by heating at 75 ° C. for 3 seconds, for example, an adhesive mixed with a colorant is further applied. At this time, wax is simultaneously applied as necessary. The thus obtained wood fiber containing the adhesive mixed with the coloring agent is classified, and after removing foreign matter, is fed under pressure and is formed into a mat shape in a forming step. After the formed mat is temporarily pressed by a roll, it is hot-pressed and fully pressed. The hot press conditions are appropriately set by selecting the resin used as the adhesive. For example, the press pressure is about 20 kgf / cm ² and the press temperature is about 2 kgf / cm ² .
The temperature is set to 00 ° C. The pressing temperature at this time greatly varies depending on the selection of the resin, but is usually set at a level of several minutes. After the thus obtained press-formed product is once mounted, surface finishing is performed by a sander, and the resultant is further cut to a desired size to obtain a medium-density fiberboard.

In the medium-density fiberboard thus obtained, if the adhesive has uneven dispersion, coloring unevenness occurs. Therefore, it is necessary to observe whether or not the obtained medium-density fiberboard has uneven coloring. Accordingly, the presence or absence of uneven dispersion of the adhesive can be easily confirmed, and a decrease in the peel strength of the medium-density fiberboard due to the uneven dispersion of the adhesive can be easily inspected nondestructively. Also, since the medium density fiberboard can be colored to any color, when fabricating building materials such as flooring and wall materials by attaching a decorative sheet or the like to the medium density fiberboard, It is colored similar to the decorative sheet etc. to prevent the color of the medium density fiberboard from being noticeable on the edge of the building material, or to make the color of the medium density fiberboard visible through the surface of the building material. And a building material having a good appearance can be obtained. Further, the medium-density fiberboard colored in this way has discriminative properties, and the manufacturer can be determined by visually checking the colored color.

[0013] Here, wood fibers in the medium density fiberboard,
The ratio of the adhesive and the colorant is such that the adhesive is 10 to 20 parts by weight and the colorant is 0.2 to 20 parts by weight per 100 parts by weight of the wood fiber.
It is preferred that the amount be in parts by weight. When the proportion of the adhesive is smaller than this range, there is a possibility that the planar tensile strength, the bending strength and the like of the medium-density fiberboard are reduced, and the water resistance is reduced. If the ratio of the adhesive is larger than this range, the production cost will increase, and at the time of molding, the specific gravity of the wood fiber mixed with the adhesive mixed with the coloring agent will be too large, and it will be difficult to pump the material. At the same time, the curing time at the time of hot pressing is increased, and there is a possibility that a resin pool is generated in the formed medium density fiberboard. If the proportion of the coloring agent is smaller than this range, it becomes difficult to sufficiently color the medium-density fiberboard. If the proportion of the coloring agent is larger than this range, the adhesive strength of the adhesive is reduced, the planar tensile strength of the medium density fiberboard, the bending strength, and the like may be reduced, or the water resistance may be reduced. Also, at the time of molding, the specific gravity of the wood fiber mixed with the adhesive mixed with the coloring agent becomes too large, and it becomes difficult to feed the wood fiber.

[0014]

As described above, the method for producing a medium-density fiberboard according to the present invention comprises mixing an adhesive mixed with a colorant into a wood fiber and pressing it with a hot press. In the obtained medium-density fiberboard, if uneven dispersion of the adhesive occurs, coloring unevenness occurs.By observing the presence or absence of uneven coloring of the obtained medium-density fiberboard, the dispersion of the adhesive is performed. The presence or absence of unevenness can be easily checked, and the decrease in peel strength of the medium-density fiberboard due to uneven dispersion of the adhesive can be easily and non-destructively inspected. When building materials such as flooring and wall materials by sticking a decorative sheet or the like to a medium-density fiberboard, the medium-density fiberboard can be colored similar to the decorative sheet or the like. Colored, medium density at the edge of the building material It is possible to prevent the color of the fiberboard from being noticeable or to prevent the color of the medium density fiberboard from being seen through from the surface of the building material, and to obtain a building material with a good appearance. Things.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a manufacturing process of a medium density fiberboard.

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Claims (2)

[Claims] 1. A method for producing a medium-density fiberboard, comprising blending an adhesive mixed with a colorant into wood fibers and hot-pressing the mixture. 2. The method according to claim 1, wherein a dye or a pigment is used as a colorant.