JPS5929422B2 - Method for manufacturing medium specific gravity fiber board with uneven pattern surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention produces decorative fibers of medium specific gravity suitable for use in wall materials, ceiling materials, etc. by carving an uneven pattern by embossing on the surface of a fiberboard that has been heat-pressed. Concerning a method of manufacturing a board.

In general, fiberboard used for wall materials, ceiling materials, etc. should be relatively high density with a specific gravity of 0.6 to 0.8 among medium specific gravity, and fiberboard with a specific gravity of 0.6 or less has a low density. If the specific gravity is too low, it lacks impact resistance, while if the specific gravity is over 0.8, the density is too high and lacks sound absorption properties, making it unsuitable for use.

By the way, fireboards obtained by simply hot-pressing a smooth surface have extremely monotonous outer surfaces and are not suitable for satisfying people's tastes, so it is necessary to carve irregularities with wood grain or various patterns on them. will be carried out.

Conventionally, when hot-pressing a felted fiber mat, the hot-pressing machine is equipped with a plate with a concave-convex pattern engraved on it, and the fiber mat is hot-pressed with this, thereby forming the board at the same time. It is manufactured by carving an uneven pattern on its surface.

With this method, even when molding a relatively high density fiberboard with a specific gravity of about 0.6 to 0.8, an uneven pattern can be engraved on the surface.
Because the mother plate with the uneven pattern used for this process is extremely expensive, it cannot be installed in large numbers in a hot press machine, and it is not suitable for mass production due to the workability of heat pressing each sheet one by one. becomes expensive.

On the other hand, it is also possible to once heat-press the fiberboard and then continuously feed it to a press device using an embossing roll, embossing plate, etc. to carve an uneven pattern on the surface of the formed fiberboard. It is done.

In this method, simply embossing is performed using a press device, so the fiberboard can be continuously fed and the uneven pattern can be engraved one after another, thus making it possible to mass-produce the fiberboard.

However, since the fiberboard to be embossed has been heat-pressed to a nearly uniform density, it is impossible to support the high-density areas formed on such boards by embossing, and the elasticity Not only does this deform the embossed part, making it impossible to fix the unevenness, but also creates a density difference between the high-density part caused by the embossment and other parts, which tends to cause delamination of the embossing roll.
Furthermore, it may also cause cracks to occur due to density differences after the product is completed.

Therefore, the present invention aims to manufacture a fiberboard to obtain a medium specific gravity fiberboard with a specific gravity of 0.6 to 0.8 while carving an uneven pattern on the fiberboard once formed to be suitable for mass production. The purpose is to provide a method.

This will be explained in detail as follows.

In this method, first, a medium specific gravity fiberboard having a surface layer formed with a lower density than at least a relatively high density core layer is manufactured by a dry method.

To this fiberboard, at least about 15 to 20% of a thermosetting resin liquid with a resin content of about 38 to 40% is added as the fiber of the core layer, and this water content is reduced to 1.
Wood fibers with a humidity level of about 0 to 15% are used.

As a surface layer, wood fibers to which about 10 to 15% of a thermosetting resin liquid with a resin content of about 38 to 40% is added and whose moisture content is adjusted to about 5 to 10% are used.

Note that the fiber for this back layer may be of the same quality as either the above-mentioned surface layer or core layer.

These are air-felted using a conventional dry method to obtain a fiber mat, which is then pressed to eliminate air in the fiber mat and temporarily pressed to an appropriate thickness.

Then, a main pressing process is applied to this using a flat plate hot press, and at this time, the distance bar is used to maintain the hot pressing interval at a predetermined thickness.

This pressing condition depends on the properties of the thermosetting resin impregnated into the fiber to be pressed, but when using a low-temperature fast-setting resin such as urea melamine, the temperature is 140 to 160.
℃, a pressure of 50 kg/ca, and a time of about 5 to 7 minutes is sufficient.

Note that the resin added to this fiber is not limited to the low-temperature fast-curing resin such as the above-mentioned urea melamine, but may also be a high-temperature slow-curing resin such as phenol resin.

In the case of fiberboard formed by thermo-pressure molding in this way, at least the surface layer made of fibers with a relatively small amount of resin added and a low moisture content compared to the core layer starts to harden early, and the specific gravity of that part A relatively low-density layer of about 1 to 2 u corresponding to a specific gravity of 0.4 to 0.6 is formed, while a relatively high-density layer corresponding to a specific gravity of 0.6 to 0.8 is formed below it. is formed, resulting in a medium specific gravity fiberboard with a moisture content of about 8 to 9%.

Next, this fiberboard is used as a substrate, and a thermosetting resin liquid is applied to the surface thereof.

For this resin, urea melamine, urea melamine, etc. can be used, and it is coated in a coating device such as a roll coater, a flow coater, or a spray coater at a rate of about 1 to 3 g/
Approximately m' is applied.

The resin is allowed to penetrate into the relatively sparse surface layer of the fiberboard substrate.

To increase the permeability of this resin, methyl alcohol,
Approximately 3 to 4% of alcohol such as ethyl alcohol can be added.

Also, instead of alcohol, a surfactant of about 1 to 4% may be added, but if this surfactant remains active in the fiberboard, its water absorption and hygroscopicity will be reduced, which is preferable. Therefore, when using it, it is necessary to ensure that its activity in the fiberboard is lost.

The resin liquid applied to the surface in this manner quickly penetrates into the surface layer of the fiberboard and wets the surface layer, which has a relatively low density.

In this state, the resin-impregnated surface layer of the fiberboard is hot-pressed by an embossing roll or plate having an uneven surface, and is pressed under sufficient heat to harden the resin impregnated into the substrate layer.

This heat pressing is performed at a temperature of 110-130°C and a pressure of 5-7k.
y/i for about 4 to 6 minutes, and the surface layer has a depth of 0.8
This is done so that a recess of about mm is formed.

Along with this heat pressing, the resin impregnated into the surface layer hardens to an extent corresponding to a specific gravity of 0.6 to 0.8, and at the same time, the surface of the substrate, which has a relatively high density, has an uneven pattern. is engraved.

Example 1 Tree efficiency 40 as fiber for back layer and core layer
Using resin-impregnated wood fibers with a water content of 10% by adding 15% of phenolic resin liquid to the wood fibers,
As fibers for the surface layer, resin-impregnated wood fibers were made by adding 10% of 40% phenol resin liquid to the wood fibers to make the moisture content 5%. Got Matt.

The mat was heated at 200°G15 using a flat plate hot press machine.
Pressed for 7 minutes at 0 kg/C11 yen to a thickness of 2 m.
A board with a total thickness of 7 mm with a surface layer of m was obtained.

At this stage, the specific gravity of the surface layer was 0.5, and the specific gravity of the middle core layer was 0.8.

A urea melamine resin solution containing 2% methyl alcohol was applied to the surface layer of the obtained board at a rate of 15 g/cm2, and was heated at 120°C using an embossing plate at a rate of 7 kg/cr.
Pressing was carried out for 4 minutes under iY conditions to obtain an embossed fiberboard with a depth of approximately 0.8 mm.

The specific gravity of the product was 0.8, and no delamination or cracking was observed.

Example 2 As fibers for the back layer and in the core layer, resin ratio 40
Add 20% of urea melamine resin liquid to bring the water content to 15%.
% resin-impregnated wood fiber, and as the surface layer fiber, urea melamine resin liquid with a resin percentage of 40% was used.
A fiber mat was obtained by air felting and prepressing using a conventional method using resin-impregnated fibers containing 5% of the resin and having a water content of 10%.

The mat was heated at 140°C and 50°C using a flat plate hot press machine.
Pressed for 5 minutes at kg/ffl to a thickness of 2 mm.

A board with a total thickness of 10 mm and a surface layer of 10 mm was obtained.

At this stage, the specific gravity of the surface layer was 0.45, and the specific gravity of the middle core layer was 0.8.

The surface layer of the obtained board was subjected to the same treatment as in Example 1 to obtain a fiberboard with an embossed pattern having a depth of about 0.8 mm.

The specific gravity of the product was 0.6, and no delamination or cracks were observed.

In this way, according to the present invention, it is possible to obtain a medium specific gravity fiberboard with a specific gravity of 0.6 to 0.8 having an uneven pattern engraved on its surface, and furthermore, the embossing process can be performed at low pressure in a short time. Therefore, this continuous production can be carried out efficiently.

In addition, during this manufacturing process, the pressing force of the embossing is supported by the relatively hard layer existing in the lower layer during the embossing process, so obvious unevenness is formed.In particular, the specific gravity of the embossed part is also lower than the core layer Since the fiber mat with a uniform density is formed as a medium specific gravity fiber board layer similar to the above, the phenomenon of delamination does not occur.

Claims (1)

[Claims] 1. In the dry fiberboard manufacturing process, at least two steps are taken so that the amount of thermosetting resin added and the moisture content are relatively low in at least the surface layer of the mat formed by felting with respect to other mat parts. After felting the laminated mat of layers and prepressing this,
A medium specific gravity fiberboard substrate with at least one layer of low specific gravity fibers on the surface layer is formed by heat molding using a roll press or a flat plate press, and a certain amount of solvent-based thermosetting resin is applied to the surface of this substrate. The resin is impregnated into the surface layer of the substrate, and then the resin-impregnated substrate is heat-pressed using an embossing roll and an embossing machine, so that the surface layer of the substrate is formed with a surface unevenness pattern having a uniform density almost with the center layer. A method for manufacturing a medium specific gravity fiberboard having an uneven pattern surface, characterized by forming a layer with a rough pattern.