JPH0754482A - Form member - Google Patents

Abstract

PURPOSE:To increase strength and impermiability, by providing a hard layer having a higher specific gravity than the inside layer and a specified hardness, at the surface of at least one side of a wooden fiber plate. CONSTITUTION:A wooden fiber plate 1 is formed by use of a coniferous tree like a pine tree, a Japanese cedar, a cypress, etc., or a broad-leaved tree like a kapul, a lauan, a chestnut, a poplar, etc., as a raw material. The surface of wooden fiber plate 1 is heated and compressed under an increased condition of water content to form hard layers 2, 2' having a higher specific gravity than the inside layer and 0.5kgf/mm or more in hardness according to the hardness testing method of wooden material stipulated in JIS-Z-2117.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a formwork material used for forming a formwork, and more particularly to a concrete formwork material having excellent releasability from concrete.

[0002]

2. Description of the Related Art Conventionally, a large amount of concrete formwork using plywood has been used because of its easy handling.

Further, in order to improve the surface property of the plywood of the concrete formwork and increase the number of times of diversion, a synthetic resin film is formed on the surface of the plywood, or a paper impregnated with paper impregnated with a synthetic resin is applied to the plywood. By adhering to the surface,
A plywood concrete formwork having improved peeling performance from concrete is known.

[0004]

Plywood is manufactured by laminating and bonding veneer from which natural wood has been thinly peeled off. At present, the problem of depletion of natural resources has been widely taken up. As it becomes increasingly difficult to do
The quality of supplied raw wood is also declining.

For this reason, it is difficult to obtain a large amount of high quality veneer and stably, and it is becoming increasingly difficult to supply high quality plywood to the market.

Further, in the case of plywood used as a building or furniture member, the period of use of plywood used as a concrete formwork is significantly shorter than that of plywood used for at least 10 years. The reality is that they are discarded in bulk after use.

[0007] This problem is expected to become more serious in the future in view of the active call for recycling of natural resources and the like, and it is expected that the problem of form materials using substitutes instead of plywood will increase. Aspiring to be offered.

[0008] Further, in the case where the concrete peeling performance is enhanced by forming a synthetic resin film on the surface of the plywood or adhering synthetic resin impregnated paper, it is clear that the veneer is a veneer on the surface veneer of the plywood. Since it is used to coat materials with different physical properties, it is easily scratched, causing problems such as cracking of the synthetic resin coating formed on the surface by repeated use and peeling of the impregnated paper from the plywood surface. Had.

[0009]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems in the prior art and to provide a new concrete form material which can be used as a substitute for a plywood form. To do.

That is, the formwork material according to the present invention is made of wood fiberboard, has a higher specific gravity on at least one surface than the inner layer part, and has a wood hardness test method defined in JIS-Z-2117. Hardness is 0.50kgf / mm
It is characterized by having a hard layer of ² or more.

That is, the main feature of the present invention is that a wood fiberboard having a hard layer on at least one surface thereof is used as the mold material. The hard layer has a specific gravity higher than that of the inner layer portion, and has a hardness of 0.50 kgf / based on the hardness test method for wood specified in JIS-Z-2117.
mm ² or more. Hardness of the hard layer is 0.50kg
When it is less than f / mm ² , the aggregate becomes small during concrete pouring or compaction by a vibrator, so that damages such as dents and scratches are likely to occur on the inner surface of the form material. For this reason, the peelability from concrete deteriorates, and the smoothness of the concrete surface is lost even after peeling, which reduces the number of times of diversion as a formwork.

Further, since the hard surface layer has a higher specific gravity than the inner layer portion, it is excellent in tensile strength, compressive strength and bending strength, and has a very small bending deflection amount.
Suitable for use as a mold material. Further, the hard surface layer has a high specific gravity and thus is impermeable to water.

Generally, the overall specific gravity of the wood fiberboard is 0.4 to
The specific gravity of the hard layer is 0.8 to 1.2.

The wood fiber board having the above-mentioned structure is
It can be manufactured as follows. That is, for example, in a manufacturing process by a dry method, pine, cedar, wood chips such as softwood materials such as cypress, Kapole, Lauan, chestnut, poplar, etc. are defibrated from wood chips or waste wood chips such as construction, or sander dust, A wood fiber is obtained by appropriately mixing wood dust such as sawdust, an adhesive, a sizing agent, etc. are added to the wood fiber and then dried, and the wood fiber is accumulated on a screen conveyor by a forming device and temporarily pressed. To obtain a wood fiber mat, which is then cut into a certain size to form a standard length wood fiber mat, and the wood fiber board is obtained by heating and pressing.

In this manufacturing process, water is applied to the upper surface and / or the lower surface of the regular-length wood fiber mat, or a water-retaining sheet-like material such as a non-woven fabric, paper, cloth, etc. It is placed on the upper surface and / or the lower surface of, and heated and pressed in this state. As a result, heating and pressing are performed with the water content of the front and back portions being increased, so that a hard layer is formed on the water application surface or the mounting surface side of the sheet-like material.

In this case, by appropriately adjusting the amount of water applied, the water content of the sheet-like material, or the amount of the adhesive added to the wood fibers and the water content of the wood fibers, the hard layer is formed. A desired specific gravity and layer thickness can be given.

In this way, a wood fiberboard having a hard layer having a high specific gravity on the front surface side (or both front and back surfaces) having a desired hardness can be obtained.

In this wood fiber board, a thin surface layer having a low specific gravity may be formed by pre-cure of the adhesive at the time of heating and pressing. Therefore, at least the surface side may be sanded if necessary to the thin surface layer having a low specific gravity. Is removed to expose the hard layer to the surface.

The surface hard layer is exposed and formed on at least one surface of the wood fiberboard, and the surface hard layer is arranged on the inner surface of the mold to form the mold.

[0020]

Since the hard layer having high specific gravity and high hardness is formed on the inner surface of the mold, it exhibits sufficient strength as a mold material and is excellent in water impermeability.

The hard surface layer has excellent wear resistance, good peelability from concrete, and a smooth concrete surface.

[0022]

EXAMPLE FIG. 1 shows an example of the construction of a mold material according to the present invention.
A hard layer 2 having a higher specific gravity than the inner layer portion is formed on the front surface side of a wood fiber board 1 which is a substrate. The hard layer 2 is JIS-
It has a hardness of 0.50 kgf / mm ² or more according to the hardness test method for wood specified in Z-2117. In addition,
In this example, the hard layer 2 ′ is also provided on the back side of the wood fiberboard 1.
Is formed, whereby the expansion and contraction of the entire mold material due to moisture absorption and desorption is sufficiently suppressed. However, the backside hard layer 2 ′ is not an essential component of the present invention,
If the hard layer 2 is arranged on the inner surface of the mold to form the mold, the back hard layer 2'can be omitted.

[0023]

According to the present invention, there is provided a mold material which is excellent in tensile strength, compressive strength and bending strength, has an extremely small bending deflection amount, and is also excellent in water impermeability.

A hard layer having a high specific gravity and a high hardness is formed on the surface of the mold material of the present invention, and the hard layer is arranged on the inner surface of the mold to form the mold. Even if the aggregates collide during compaction, they will not be damaged, the peelability from concrete will be enhanced, and the concrete surface can be finished smooth.

Therefore, the mold material according to the present invention can be suitably used as a substitute for a plywood mold in the present day when it is difficult to obtain a good quality single plate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration example of a mold material of the present invention.

[Explanation of symbols]

 1 Wood fiber board (substrate) 2 Hard layer

Claims (1)

[Claims] 1. A wood fiberboard, which has a specific gravity of at least one surface thereof higher than that of an inner layer portion, and JIS-Z.
A form material having a hard layer having a hardness of 0.50 kgf / mm ² or more according to the hardness test method for wood specified in 2117.