JPS6367599B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is useful as a core material for furniture materials such as furniture shelves, side panels, and top boards, or as cores and decorative laminate substrates for partition panels and other various panels, and is lightweight and has excellent strength. The present invention relates to a method for manufacturing fiberboard having a medium specific gravity of 0.4 to 0.6.

Traditionally, plywood and particle board have been mainly used as materials for making furniture panels such as shelves, side panels, and top panels. Since particle board has a high specific gravity of 0.6 to 0.8, the total weight of the furniture becomes large, making it difficult to handle and increasing the cost of transporting the furniture.

Furthermore, since particle board is made by bonding small pieces of wood together using a large amount of adhesive such as urea resin or phenolic resin, it has a strong formalin odor, and this odor of formalin can accumulate inside the furniture and cause discomfort. There were flaws.

On the other hand, wood fiberboard, which is made from wood fibers using a dry or wet papermaking method, is known as a wood board that is lighter than particle board. This method requires a large amount of adhesive, which increases the cost. Furthermore, when a phenolic resin adhesive is used, there is a problem in that a formalin odor is generated due to the formaldehyde released. According to this paper, since the paper is made using water as a solvent, formaldehyde is eluted into the water and an odorless product is obtained, but on the other hand, the binder also flows out into the white water, resulting in a decrease in strength.

Furthermore, fiberboard made from paper-made pine by high-pressure pressing into hardboard has problems such as a specific gravity of 0.6 or more, which increases the weight, and makes the entire board hard and robust, resulting in poor workability.

In order to eliminate such drawbacks, the present invention has 10 points.
Paper-made pine that has been dried to a moisture content of ~60% is heated and pressed between the hot plates of a hot press while regulating its thickness with a distance bar, resulting in a specific gravity of 0.4 with high density on the front and back layers and low density on the center layer. The present invention provides a method for producing a medium specific gravity fiberboard characterized by forming a fiberboard with a density of ~0.6.

An embodiment of the present invention will be described with reference to the drawings. First, a wet mat 1 of wood fiberboard is made by a wet paper making method. The composition of this wet mat is preferably such that it can be formed by reducing the outflow of the binder during wet papermaking, and for this purpose, a thermosetting resin such as a powdered phenolic resin and a powdered starch are used, and In order to increase the fixation rate of a binder such as powdered starch between the wood fibers, which is the main raw material of wet mat, it is preferable to use a paper made by mixing waste paper pulp.

The wet pine 1 thus paper-formed is heated appropriately to adjust it to a semi-dry pine.

Here, the moisture content of the paper-made wet pine is 10~10.
The reason for drying to 60% is that the moisture content immediately after papermaking is
If 150 to 200% pine is inserted directly into a hot press, it will take a long time to dry, resulting in a significant drop in productivity. This is because the above-mentioned wire mesh digs into the surface of the fiberboard after pressing, resulting in the appearance of an uneven mesh, and the surface cannot be finished to a smooth surface.
At this time, if the moisture content of the mat 1 is less than 10%, the steam effect from the later hot pressing cannot be expected to be sufficient, making it difficult to plasticize the fibers in the front and back layers of the mat 1, resulting in a decrease in strength. Therefore, it is not possible to obtain board materials suitable for furniture materials, etc., and if the moisture content exceeds 60%, steam pressure accumulates inside the mat 1 during hot pressing, which tends to cause the so-called puncture phenomenon when taking it out from the press. In addition, since it takes a long time to raise the temperature, it is necessary to adjust the moisture content of the pine 1 to a range of 10 to 60%. In particular, Matsuto 1 has a moisture content of 10~
If adjusted to a 30% semi-dry condition, the temperature will be 120℃, 5
This is preferable because it can be completely dried by hot pressing for a few minutes, which shortens the press cycle and improves productivity.

Next, this semi-dry pine 1 is heated to 100 to 200℃.
It is inserted between the upper and lower hot plates 2 and 3 of a heated hot press to heat and compress.

At this time, metal distance bars 4, 4 whose height is smaller than the thickness of the mat 1 are arranged along the side end surface of the mat 1 placed on the lower hot plate 3, and then the mat 1 is heated by a hot press. It is heated and pressed.

During this hot pressing, if the compression pressure is less than 2 kg/cm ² , the front and back layers of the mat cannot be sufficiently strengthened, so it is preferable to carry out the compression with a pressing force of 2 kg/cm ² or more.

In addition, the temperature of the press during this hot pressing is appropriately determined depending on the moisture content of the soft fiberboard to be pressed.
Pressing at a high temperature of 200℃ or higher tends to cause problems such as the wood fibers on the surface layer of the fiberboard burning and adhering to the pressing surface, making it difficult to obtain a smooth surface.
It is carried out at a temperature in the range of 100 to 200°C, preferably 120 to 180°C.

In this way, the upper hot plate 2 is connected to the distance bar 4 by the upper and lower hot plates 2 and 3 of the hot press of the mat 1.
When heated and compressed until it contacts the mat, the moisture contained in the pine becomes steam due to the heat of the hot plate, and the fibers are exposed to humid and high temperature conditions, softening the lignin and plasticizing the fibers. Only the front and back layer portions are densified by compression, and the hardness and strength are increased by drying between the hot plates of the press.

At this time, the central layer of the pine is prevented from being excessively compressed by the distance bar 4, and the influence of the steam and heat is reduced, so phenomena such as softening of lignin are small, and its density is slightly reduced. It only rises, and only the front and back layer portions are densified.

The fiberboard 1' obtained in this way has a three-layer structure, as shown in FIG. This increases the overall strength.
In addition, the surfaces of the front and back layers a and a' of the fiberboard are dense and smooth, and the surface condition is good, with an overall specific gravity of 0.4.
A dry medium specific gravity fiberboard of ~0.6 is formed.

Here, the heat compaction by the press is
It is necessary to keep the specific gravity of the resulting fiberboard within the range of 0.4 to 0.6.

This is because if a fiber mat with only the front and back layers in a humid state is pressurized to a specific gravity of 0.6 or higher, the intertwined portions of the wood fibers in the dry center layer will break, resulting in a decrease in strength. Furthermore, forming the fiberboard to have a specific gravity of 0.6 or more makes it impossible to achieve the original purpose of reducing the weight of furniture materials.

For this purpose, a distance bar is placed together with the mat on the lower heating plate of the hot press, and the compressed thickness of the mat during pressing is adjusted by the height of the distance bar, so that the specific gravity is 0.4 to 0.6. It is intended to obtain a fiberboard within the range of .

If you don't use distance bars like this,
The thickness and specific gravity of the resulting fiberboard vary, and the entire fiberboard becomes a hardboard, making it impossible to achieve the intended purpose.

As described above, the present invention uses a wet mat of wood fiberboard made by a wet papermaking method with a moisture content of 10 to 60.
%, and then heat-pressed the mat together with a distance bar between the hot plates of a hot press to achieve a specific gravity of 0.4 with high density on the front and back layers and low density on the center layer.
Since this relates to a method for producing a medium specific gravity fiberboard characterized by forming a fiberboard with a density of ~0.6, a distance bar of a predetermined height corresponding to the thickness and moisture content of the wet mat is placed on a hot plate of a hot press. Since the compressed thickness of the wet mat can be made equal to the height of the distance bar despite the compression by the hot press, the entire wet mat becomes hardboard due to excessive heat pressure. In addition, only the front and back layers can be subjected to sufficient heat and pressure treatment to form a high-density fiber layer, and the height of the distance bar can control the degree of compression of the hot press. can be adjusted, it is possible to easily obtain fiberboard with a specific gravity of 0.4 to 0.6, and also to produce a large amount of medium-specific gravity fiberboard with excellent strength and almost no variation in thickness or specific gravity. be.

Furthermore, since the fiberboard obtained by the method of the present invention has a strength that can replace particle board, it can be used as a core material for furniture and other various panels to significantly reduce the weight of these members. It is something.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a simplified front view showing the manufacturing method thereof, and FIG. 2 is a sectional view of the obtained fiberboard. 1...Matsuto, 2, 3...Upper and lower hot plates, 4, 4...
...Distance bar, a, a'...Front and back layer part, b...
...Central layer.

Claims (1)

[Claims] 1. A wet mat of wood fiberboard made by a wet paper making method is semi-dried to a moisture content of 10 to 60%, and then the mat is heated between hot plates of a hot press together with a distance bar. A method for producing a medium-specific gravity fiberboard, which comprises pressing to form a fiberboard having a specific gravity of 0.4 to 0.6, with high density front and back layers and low density central layer. 2. The wet mat of the wood fiberboard has a medium specific gravity according to claim 1, characterized in that it is made by wet paper-making by mixing appropriate amounts of powdered starch, powdered phenolic resin, and waste paper pulp with wood fibers. Method of manufacturing fiberboard.