JP2560311Y2 - 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.

[0003] Further, the period of use of plywood used as a concrete formwork is discarded in large quantities after a very short period of use, compared to plywood used for architectural or furniture parts used for at least 10 years. At present, the natural resources recycling campaign is being actively promoted, and it is expected that this problem will become more serious in the future, and provision of formwork materials using alternatives to plywood will be provided. Is eagerly awaited.

In order to improve the surface properties of the plywood of the 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 synthetic resin film is applied to the plywood surface. BACKGROUND ART A plywood concrete formwork in which the peeling performance with concrete is enhanced by bonding or the like is known.

[0005] However, in these molds, a new synthetic resin film having properties clearly different from those of the plywood is applied on the surface veneer of the plywood, or an impregnated paper is bonded through an adhesive. There is a problem that the synthetic resin film formed on the surface is cracked by repeated use because of being easily scratched, and the impregnated paper peels off from the plywood surface.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a new concrete form material made of resource-rich materials which can be used as a substitute for plywood.

[0007]

According to the present invention, 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. Is a concrete formwork material impregnated with a synthetic resin such that a synthetic resin layer does not remain on at least one surface of at least one surface of a wood fiber board exposed on the front surface or the back surface.

[0008]

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 made of a wood fiber board having a three-layer structure obtained by integral molding and having a central layer 2 disposed therebetween and having a hard layer 1 exposed on the front and back surfaces.

Further, each hard layer 1 exposed on the front and back surfaces
A synthetic resin impregnated layer 1a impregnated with a synthetic resin such that no synthetic resin layer remains on the surface is formed on the inner surface portion. FIG. 1 shows a state in which the synthetic resin impregnated layer is formed only on the surface portion in the hard layer 1. However, the entire hard layer 1 or the central layer 2 may be impregnated with the synthetic resin.

The hard layer 1 of the wood fiber board 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 center layer 2 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 a specific gravity of at least 0. 1 g / cm ³ or more preferably it is preferred to have a difference in specific gravity between 0.3 to 0.8 g / cm ^3.

Since the hard layer 1 having higher specific gravity and higher tensile strength and compressive strength than the central layer is disposed on the front and back layers, the surface hardness is high, the scratch is hardly formed, and the plate material as a whole has excellent bending strength. Also, the amount of deflection due to a unit load is very small.

The specific gravity of the hard layer is lower than 0.8 g / cm ³ , the water impermeability is low, and the hard layer is easily scratched and the amount of deflection due to the lateral pressure increases, which is not preferable as a concrete form material.

On the other hand, if the specific gravity of the hard layer is greater than 1.4 g / cm ³ , the body impact performance is poor and the plate becomes brittle, so that when the worker throws the plate and collides with the ground, cracks are formed. And the like are not preferred.

On the other hand, if the specific gravity of the central layer is lower than 0.4 g / cm ³ , sufficient strength cannot be obtained, and conversely, 0.75 g / cm 3
^{If it is} larger than ³ , the overall 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 rigidity can 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.

On the other hand, 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 layers of the front and back layers have a high specific gravity, so that the wood fibers are in a dense state and shrinkage in the plane direction is unlikely to occur. Since the specific gravity is small, the wood fibers are in a sparse state and easily shrink, and the like. This is not preferable because delamination easily occurs between the center layer and the hard layer.

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

Since a specific gravity distribution occurs in the hard layer 1 of the obtained wood fiber board, sanding is performed as necessary, and a layer (surface) having a particularly high specific gravity in the hard layer 1 is exposed to the surface. , Bending strength and bending performance.

Further, since the hard layer 1 has higher water impermeability than the center layer 2, it has an effect of remarkably reducing the water absorption into the plate material, and peels off from concrete when used as a concrete form material. It has good performance, and can be used repeatedly as a concrete form material.

The specific gravity of the hard layer 1 is 0.8 to 1.4 g / cm ³ , preferably 1.
Rosin size, wax size, and cumarone that impart water-based water to each of the wood fibers forming the hard layer 1 in the process of manufacturing the wood fiber board, in addition to being formed at 0 to 1.2 g / cm ^3. By attaching or containing a sizing agent such as rosin size and asphalt size in an amount of 2 to 8% by weight, the impermeable property of the hard layer 1 is further improved by its combined action.

When the content of the sizing agent is less than 2% by weight, sufficient water impermeability is not provided, and when the content is more than 8% by weight, the adhesive strength between the wood fibers of the hard layer 1 is reduced. It is not preferable.

As described above, since the sizing agent for imparting water resistance is applied or contained on each of the wood fibers forming the hard layer 1, the hard layer 1 is integrally formed. 1 as a whole is a water-impermeable layer, which solves the problems of cracking or peeling of the conventional resin film formed on the surface.

Further, a synthetic resin such as a phenol resin, an amino resin, a polyester resin, a diallyl phthalate resin or a urea resin is applied to such a wood fiber board in a liquid form by a coating roll or spray and then cured by heating. By spraying the powder and heating and pressing, the synthetic resin impregnated layer 1a impregnated without leaving the synthetic resin layer on the one side surface, the front and back surfaces, the four circumferential surfaces or the six surfaces including the kiguchi portion is formed. In addition, the surface of the wood fiber board can be made non-permeable, and when used as a concrete form material, has excellent peeling properties from concrete, and can be used repeatedly.

[0025] Further, the impregnation of the synthetic resin particularly increases the specific gravity of the portion, thereby increasing the bending strength as a plate material.

However, if the synthetic resin layer (coating) remains on the surface of the wood fiberboard, the synthetic resin layer formed on the surface may crack during repeated use, or the synthetic resin layer may be removed from the surface of the wood fiber board. In addition to the problem of easy peeling, the concrete surface after peeling becomes smooth mirror-like, and in the subsequent application of mortar, the adhesion of the mortar is low due to the very low anchoring effect of the surface. It is not preferable because it is easy.

As described above, the concrete form material of the present invention has a very low 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 and back surfaces and the center layer 2 disposed therebetween are integrally formed by heating and pressing in a wood fiber board manufacturing process. The hard layer 1 and the central layer 2 are integrally continuous with each other due to the entanglement of the wood fibers, so that a single plate is formed by bonding a plurality of plates with an adhesive. In addition, there is no problem of peeling between plate materials.

The wood fibers used for 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 a manufacturing process of a dry wood fiber board, a wood fiber dried by adding an adhesive and dried is deposited on a screen conveyor by a forming device, and is thickened by a shaving rotor. Is adjusted and then pre-pressed to obtain a wood fiber mat, and then the fixed-size mat cut to a certain size is heated and pressed to use a medium specific gravity fiber board.

On the upper and lower surfaces of the fixed-size mat obtained in the same manner as described above, a water-retaining or sheet-like material such as nonwoven fabric, paper, cloth, etc., which has been coated with water or is contained, is heated and pressed. By doing so, 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, so that the hard layer 1 having a very high specific gravity can be formed on the front and back surfaces.

As a forming apparatus for depositing wood fibers on the screen conveyor, three forming apparatuses for separately forming the back layer forming wood fibers, the middle layer forming wood fibers, and the 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 way, the front and back surfaces of the wood fiber board are
The hard layer 1 having higher specific gravity and higher water impermeability than the center layer 2 is formed.

Further, since specific gravity distribution occurs in the hard layer 1 of the obtained wood fiber board, sanding is performed as necessary, and a layer (surface) having a particularly high specific gravity in the hard layer 1 is exposed to the surface. In addition, the performance such as water impermeability, bending strength, and deflection is further improved, the number of times that the concrete formwork can be used repeatedly is increased, and the performance against lateral pressure from cement is also improved.

Further, as a method of impregnating the synthetic resin so that the synthetic resin layer does not remain on at least one surface of the wood fiber board having such a constitution, the wood fibers deposited on the screen conveyor are temporarily pressed. The synthetic resin powder is evenly sprayed on the surface of the wood fiber mat obtained as described above and heated and pressed, whereby a wood fiber board can be produced and a synthetic resin impregnated layer can be formed on the surface at the same time.

Further, the synthetic resin in a liquid state is applied to the surface of the wood fiber board by an application roll or spray, and the surface of the wood fiber board can be impregnated and cured with the synthetic resin by passing a plurality of heated rolls. By using the same synthetic resin as the main synthetic resin constituting the adhesive applied to the wood fiber as the synthetic resin used at this time, the impregnation into the wood fiber can be performed well, This is preferred in that no intervening curing inhibition occurs.

By thus impregnating the surface of the wood fiberboard with the synthetic resin so that the synthetic resin layer is not formed on the surface of the wood fiberboard, the exfoliation performance from concrete when used as a concrete form material is excellent. It can be used.

However, if the amount of the synthetic resin added is too large,
If the step of impregnating and hardening the wood fiber board is insufficient, the synthetic resin cannot penetrate the wood fiber board completely and a synthetic resin layer is formed on the surface.

When the synthetic resin layer remaining on the surface of the wood fiberboard is used as a concrete form,
Problems such as cracks in the synthetic resin layer or peeling of the synthetic resin layer during repeated use, or the concrete surface becomes smooth mirror-like after the concrete form is removed, and mortar is superimposed on it When the coating is performed, it is not preferable because it has a problem such as easy peeling.

[0041]

[Effect of the Invention] The concrete formwork of the present invention is made of a wood fiber board obtained by heating and pressing wood fibers, and this wood fiber board is obtained by crushing or fibrillating raw wood having a defect that cannot be used as a veneer. Since it can be obtained by using things, resources can be used effectively and it can help to prevent the destruction of nature.

Further, the hard layer exposed on the front and back surfaces has a high specific gravity as compared with the center layer, and has a high water impermeability due to the combined effect of having a large sizing agent content of 2% or more in the wood fiber, and has a high water impermeability. Is a concrete form material excellent in the performance of peeling off from concrete because the synthetic resin is impregnated so as not to leave a synthetic resin layer on the surface.

Further, the hard layer is integrally formed with the sizing agent for imparting water resistance and the synthetic resin impregnated on the surface being applied or contained on each of the wood fibers forming the hard layer. Therefore, the entire hard layer forms a highly water-impermeable layer, and the problem such as cracking or peeling of the conventional resin film formed on the surface can be solved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a concrete form material of the present invention,

[Explanation of symbols]

 1: hard layer, 1a: synthetic resin impregnated layer, 2: central layer.

Claims (1)

(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 formwork material impregnated with a synthetic resin such that a synthetic resin layer does not remain on at least one surface of at least one surface of a wood fiber board exposed on the front or back surface.