JP2554273Y2 - Concrete formwork - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete formwork made of a wood fiber board which is excellent in peelability from concrete and is frequently used.

[0002]

2. Description of the Related Art Conventionally, concrete forms using plywood have been used in large quantities because of their easy handling. This plywood is manufactured by laminating and bonding veneers made of natural wood that have been thinly peeled.At present, the issue of depletion of natural resources has become a major issue around the world. At the same time, as the quality of raw wood deteriorates, it becomes difficult to obtain a large amount of high quality veneer used for veneer, and it is becoming difficult to supply a large amount of high quality plywood to the market. Furthermore, the period of use of plywood used as a concrete formwork is such that plywood used as a building or furniture member is used for a period of at least 10 years or more, and is discarded in large quantities after use for an extremely short period of time. At present, the natural resource recycling movement is being actively called for, and it is expected that this problem will become even more serious in the future, and there is an eager desire to provide formwork materials using alternatives to plywood. ing.

Further, in order to improve the surface properties of plywood of a concrete formwork and to increase the number of diversions, a plywood surface having a synthetic resin film formed thereon or a paper impregnated with a synthetic resin impregnated with a plywood surface. BACKGROUND ART A plywood concrete formwork in which the peeling performance with concrete is enhanced by bonding or the like is known.

[0004] However, these molds are made by applying a synthetic resin film by applying a synthetic resin film or bonding an impregnated paper via an adhesive, since the surface veneer of the plywood has a low specific gravity and thus has a low impact resistance. In addition, there is a problem that the synthetic resin film formed on the surface is easily cracked due to repeated use, cracks are formed, and the impregnated paper is peeled off from the plywood surface.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been completed as a result of devise for the purpose of providing a new concrete form material which can be used as a substitute for plywood. That is, according to the present invention, the hard layer 1 having a higher specific gravity than the center layer 2 in the thickness direction and having higher water impermeability than the center layer 2 is provided on the front and back layers, and at least one of the hard layers 1 is formed on the front surface or the back surface. This is a concrete form material in which the water-impermeable layer 3 is formed on the exposed hard layer 1 of the wood fiber board 4 exposed to the outside.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a concrete form member of the present invention will be described below with reference to the drawings. The concrete formwork of the present invention has a structure as shown in FIG.
And a concrete form member composed of a wood fiber board 4 having a three-layer structure obtained by integral molding with a central layer 2 disposed therebetween and having a hard layer 1 exposed on the front and back surfaces. Further, a water-impermeable layer 3 is formed on the exposed hard layer 1. FIG. 2 shows another embodiment of the concrete form material of the present invention, in which the water-impermeable layer 3 is provided only on one of the front and back surfaces of the wood fiber board 4. FIG.
1 shows a case where only one of them is not exposed from the front and back surfaces of the wood fiber board 4.

The hard layer 1 of the wood fiber board 4 of the present invention has an average specific gravity of 0.8 to 1.4 g / cm ³ , preferably 1.0 to 1.2 g / cm ³ , The specific gravity of the central layer 2 in the meantime is in the range of 0.4 to 0.75 g / cm ³ , preferably 0.6 to 0.7 g / cm ³ , and the hard layer 1 has at least 0 0.1 g / cm ³ or more, preferably 0.3 to 0.8 g / cm ³ . Since the hard layer 1 having a higher specific gravity than the center layer 2 and having excellent tensile strength and compressive strength is disposed on the front and back layers, the surface layer has high hardness and is not easily scratched, and the sheet material as a whole has excellent bending strength. The amount of deflection due to a unit load is also very small.

When the specific gravity of the hard layer 1 is lower than 0.8 g / cm ^3, it is not preferable as a concrete form material because the scratches are easily formed and the amount of deflection due to the lateral pressure increases. Further, if the specific gravity of the hard layer is more than 1.4 g / cm ³ , the impact resistance is poor and the plate becomes brittle, so that when the worker throws the plate and collides with the ground, cracks are easily formed. Is not preferred. The specific gravity of the central layer is 0.4 g
/ Cm ³ , sufficient strength cannot be obtained.
If it is more than 5 g / cm ³ , the total weight of the plate material will increase, making it difficult to handle, which is not preferable.

Further, if the difference in specific gravity between the hard layer 1 and the center layer 2 is smaller than 0.1 g / cm ³ , sufficient bending strength and sufficient bending strength will be obtained unless the thickness of the hard layer provided on the front and back layers is made as thick as the center layer.
No deflection is obtained, resulting in a heavy plate material and poor workability. Conversely, if the difference in specific gravity is larger than 0.8 g / cm ³ , a large difference occurs in the mechanical properties between the hard layer 1 and the center layer 2. For example, when a bending load is applied to the surface, the hard layer Has a high specific gravity, so that the wood fibers are in a dense state and hardly shrink in the plane direction. On the other hand, the central layer 2 has a low specific gravity, so that the wood fibers are in a sparse state and easily shrink. For example, delamination between the center layer 2 and the hard layer 1 is likely to occur due to such a difference, which is not preferable.

Such a hard layer 1 increases the water content of the wood fibers in the front and back layers during the heating and pressing in the manufacturing process of the wood fiber board 4 and increases the amount of the adhesive added to the wood fibers. Thereby, a layer having a higher specific gravity can be locally formed as compared with other portions.

Further, since a specific gravity distribution occurs in the hard layer 1 of the obtained wood fiber board 4, sanding is performed as necessary to expose a layer (surface) having a particularly high specific gravity in the hard layer 1 to the surface. Thereby, the performance such as bending strength and deflection is further improved. The water-impermeable layer 3 is formed as a water-impermeable sheet layer on an exposed hard layer of a wood fiber board by using an impregnated paper in which paper is impregnated with a synthetic resin, a metal foil such as an iron foil or a stainless steel foil via an adhesive. . Alternatively, apply a synthetic resin paint on the exposed hard layer of the wood fiberboard and dry it.
It is formed as a synthetic resin coating layer.

Further, as described above, the concrete form material of the present invention has a very light weight as a plate material due to the presence of the central layer 2 having a low specific gravity between the hard layers 1 having a high specific gravity. But the workability is good.

Further, in the concrete form material of the present invention, the hard layer 1 exposed on the front surface or the back surface and the central layer 2 disposed therebetween are integrally formed by heating and pressing in the wood fiberboard manufacturing process. Since the hard layer 1 and the central layer 2 are integrally continuous with each other due to the entanglement of the wood fibers, a single plate is formed by bonding a plurality of plates with an adhesive. However, the problem of peeling between the plate materials does not occur.

The wood fibers used in the concrete formwork of the present invention include coniferous materials such as pine, cedar, cypress and the like.
For the production of wood fiber and wood fiber board obtained by defibrating a wood chip obtained by cutting a part or waste wood that cannot be used as a board or square wood from raw wood such as rawan, kapole, chestnut, poplar, etc. Waste materials such as generated sander dust, saw dust and chip dust can be mixed and used.

The concrete form material of the present invention is, for example,
In the manufacturing process of the wood fiber board by the dry method, the wood fiber which has been defibrated and added with an adhesive and dried is deposited on a screen conveyor by a forming device, and each thickness is adjusted by a shaving rotor, and then temporarily pressed. A medium-density fiberboard obtained by obtaining a wood fiber mat and then heating and pressing the fixed-size mat cut to a predetermined size is used.

A nonwoven fabric coated or contained with water on the upper and lower surfaces of the fixed-size mat obtained in the same manner as above.
By placing a water-retaining sheet-like material such as paper or cloth and heating and pressing it, the water applied or contained in the sheet-like material is heated and pressed while being held in the wood fibers of the front and back layers. The hard layer 1 having a very high specific gravity can be formed on the front and back surfaces.

Further, as forming devices for depositing wood fibers on the screen conveyor, three forming devices for separately forming back layer forming wood fibers, middle layer forming wood fibers, and surface layer forming wood fibers and depositing them on the screen conveyor. The addition amount of the adhesive to the center layer forming wood fiber is, for example, 3 to 5% by weight, and the addition amount of the adhesive to the surface layer forming wood fiber and the back layer wood fiber is 1%.
By heating and pressing after adding 0 to 30% by weight, the specific gravity of the hard layer can be increased and the strength can be improved in accordance with the above-described method of forming the hard layer using moisture.

In a similar forming apparatus,
2-8 as the back layer forming wood fiber and the surface layer forming wood fiber
The coating agent containing or containing the weight% sizing agent is supplied to the forming apparatus, and the back layer, the middle layer, and the surface layer
After laminating and stacking the layers of wood fibers, the content of the sizing agent in the surface layer and the back layer can be adjusted to 2% by weight or more by heating and pressing.

In this manner, the hard layer 1 having higher specific gravity and higher water impermeability than the center layer 2 is formed on the front and back surfaces of the wood fiber board 4. After sanding is performed on at least one surface of the front surface or the back surface of the wood fiber board 4 obtained as shown in FIG. 2 to expose the hard layer, an adhesive is applied on the exposed hard layer, and furthermore, impregnated paper, metal foil or the like is applied. A non-permeable sheet is placed and pressed and bonded to form a non-permeable layer 3.

Alternatively, a synthetic resin paint is applied on the exposed hard layer 1 and then dried to form a synthetic resin paint film to form the water-impermeable layer 3. The synthetic resin paint film may be formed in a plurality of layers.

Also, as shown in FIG. 1, after the front and back surfaces of the wood fiber board 4 are sanded to expose the hard layers 1 on both sides, the water-impermeable layer 3 is formed on the exposed hard layer, so that the non-permeable layers 3 are formed on both the front and back surfaces. It is also possible to use a concrete form on which the water-permeable layer 3 is formed and which can be used on both sides.

Since the water-impermeable layer 3 is formed on the exposed hard layer 1, the non-water-permeable layer 3 has excellent adhesion and adhesion, and is used as a concrete form without causing peeling or the like. Can be

Further, since the hard layer 1 is located on the lower surface of the water-impermeable layer 3, the impact resistance of the surface is improved, and the hard layer 1 is hardly scratched, and is repeatedly used without problems such as cracking and peeling.

In addition, since specific gravity distribution is generated even in the hard layer 1 of the obtained wood fiber board 4, sanding is performed as necessary to expose a layer (surface) having a particularly high specific gravity in the hard layer 1 to the surface. Thereby, the performance such as bending strength and deflection is further improved, and since the non-permeable layer 3 is formed, the number of times that the concrete form can be repeatedly used increases, and the performance against lateral pressure from cement is also improved. Become.

[0025]

The concrete formwork of the present invention comprises a wood fiber board 4 obtained by heating and pressing wood fibers, and the wood fiber board 4 is used to crush or disassemble a raw wood having a defect that cannot be used as a veneer. Since it is obtained using fine fibers, it is possible to effectively use resources and to help prevent natural destruction.

Further, the hard layer 1 exposed on the front surface or the back surface has a higher specific gravity than the center layer 2, and on the surface thereof, the non-permeable layer 3 is formed on the surface. Concrete formwork.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a form material of the present invention in which non-permeable layers 3 and 3 are formed on both front and back surfaces.

FIG. 2 is a cross-sectional view of a case where the water-impermeable layer 3 is provided only on one of the front and back surfaces.

FIG. 3 is a cross-sectional view when one of the hard layers 1 and 1 is not exposed from the front and back surfaces of the wood fiber board 4;

[Explanation of symbols]

1: hard layer, 2: central layer, 3: impermeable layer, 4: wood fiberboard.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-192310 (JP, U) JP-A-61-70009 (JP, U) JP-A 5-91806 (JP, U) JP-A 5-95 91807 (JP, U) Actually open 48-59319 (JP, U)

Claims (3)

(57) [Scope of request for utility model registration] 1. A hard layer 1 having a higher specific gravity than the center layer 2 in the thickness direction and having higher water impermeability than the center layer 2 is provided on the front and back layers, and at least one of the hard layers 1 is provided.
A concrete form material in which a water-impermeable layer 3 is formed on an exposed hard layer 1 of a wood fiber board 4 exposed on the front or back surface. 2. The concrete formwork material according to claim 1, wherein the water-impermeable layer 3 is a water-impermeable sheet layer adhered via an adhesive. 3. The concrete formwork according to claim 1, wherein the water-impermeable layer 3 is a synthetic resin coating layer.