JP2544431Y2 - 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]

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, a hard layer having a higher specific gravity than the center layer in the thickness direction and having higher water impermeability than the center layer is provided on the front and back layers, and at least one hard layer is provided on the front surface or the back surface. A concrete formwork material impregnated with a water repellent such that no water repellent layer remains on at least one surface of the exposed wood fiber board.

An embodiment of the 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, a water repellent impregnated layer 1a impregnated with a water repellent is formed on the surface of each hard layer 1 exposed on the front and back surfaces so that the water repellent layer does not remain on the surface.

Although the water repellent impregnated layer in FIG. 1 shows a state in which only the surface portion in the hard layer 1 is impregnated, the water repellent may be impregnated into the entire hard layer or the central layer.

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 a higher specific gravity than the center layer and having excellent tensile strength and compressive strength is disposed on the front and back layers, the surface hardness is high and the scratch is not easily formed, and the plate material has excellent bending strength as a whole. The amount of deflection due to the load is also very small.

When the specific gravity of the hard layer is lower than 0.8 g / cm ³ , the water impermeability is low, the scratch is easily formed, and the amount of deflection due to the lateral pressure is increased.

Further, if the specific gravity of the hard layer is greater than 1.4 g / cm ³ , the striking performance is poor and the plate becomes brittle. This is not preferable because of problems such as inconvenience.

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 bending strength 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. 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 do not easily shrink in the plane direction, whereas the central layer has a low specific gravity, so the wood fibers are in a sparse state and easily shrink. Due to such a difference, delamination tends to occur between the center layer and the hard layer, which is not preferable.

Such a hard layer 1 is to increase the water content of the wood fibers in the front and back layers during the heating and pressing in the wood fiber board manufacturing process, 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.

Further, 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.

Furthermore, since the hard layer 1 has higher water impermeability than the center layer 2, it has an effect of remarkably reducing water absorption into a 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, coumarone, which imparts water resistance 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.

If the content of the sizing agent is less than 2% by weight, sufficient water impermeability cannot be imparted. If 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, the hard layer 1 is integrally formed in a state where the sizing agent for imparting water resistance is applied to or contained in each of the wood fibers forming the hard layer 1. 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.

Furthermore, rosin,
A method of applying a sizing agent such as paraffin wax, coumarone rosin, asphalt, linseed oil, or a repellent agent such as cotton oil, or a water repellent such as mineral oil, stearin oil, or heavy oil using an application roll or a spray and heating and curing. Alternatively, water repellent impregnated without leaving the water repellent layer on one surface, or the front and back surfaces, four or six peripheral surfaces including the kiguchi part, by a method of allowing to cool after dipping in the water repellent layer By forming the agent-impregnated layer 1a, the surface of the wood fiberboard can be made impermeable, and when used as a concrete form material, has excellent exfoliation performance from concrete and can be used repeatedly.

However, if the water-repellent agent layer remains on the surface of the wood fiberboard, the wax is transferred to the concrete surface, which causes undesired peeling when the mortar or the like is repeatedly applied to the concrete surface. .

As described above, the concrete form member 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 and back surfaces and the central 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 conifers such as pine, cedar and cypress, or
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 obtained, 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 conveyer 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.

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.

As the forming apparatus for depositing the 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.

As described above, 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.

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. 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 a water repellent so that a water repellent layer does not remain on at least one surface of the wood fiber board having such a constitution, a method of impregnating the wood repellent with a melted water repellent by an application roll or spray is used. The water repellent can be impregnated on the surface of the fiberboard by applying a plurality of heated rolls applied to the surface of the fiberboard.

Also, for example, paraffin wax or slack wax is immersed in a wax layer heated and melted at 100 to 130 ° C., and the whole wood fiber board is kept until the temperature of the wax in the tank is reached. By lifting the board and allowing it to flow so that no thick wax remains on the surface and leaving it at room temperature, the wax remaining on the wood fiber board surface penetrates, leaving no wax layer on the wood fiber board surface. 1a is formed.

This is because the temperature of the wood fiber board itself in the wax layer has risen to almost the same temperature as the temperature of the wax, so that the wood fiber board remains on the wood fiber board surface even after the wood fiber board is pulled up from the wax layer. The wax is kept in a molten state by the heat of the wood fiber board, and during the cooling period, all the wax is penetrated into the wood fiber board, leaving no wax layer on the wood fiber board surface. .

As described above, by impregnating the surface of the wood fiberboard with the water repellent so that the water repellent layer is not formed on the surface of the wood fiberboard, the peeling performance from concrete when used as a concrete form material is excellent. It can be used. However, if the immersion time in the water repellent is short or if a large amount of the water repellent remains on the surface after the wood fiber board is pulled up, the water repellent remains in the wood fiber even after the wood fiber board is cooled down. The water-repellent agent layer is formed on the surface without being able to completely penetrate into the plate.

When the water repellent layer remaining on the surface of the wood fiberboard is used as a concrete form, the water repellent is transferred to the concrete surface, and then the work such as overcoating the mortar on the concrete surface is performed. This is not preferable because it has an adverse effect on

[0037]

[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 compared to the center layer, and has a high water impermeability due to the combined action 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 from concrete because the water repellent is impregnated so as not to leave a water repellent layer on the surface.

Further, since the sizing agent for imparting water resistance is applied or contained on each of the wood fibers forming the hard layer, the hard layer is integrally formed, so that the entire hard layer is impervious to water. By forming a high-performance layer, problems 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, 2: Central layer, 1a: Water repellent impregnated layer.

Claims (1)

(57) [Scope of request for utility model registration] 1. A hard layer having a higher specific gravity than the center layer in the thickness direction and having higher water impermeability than the center layer is provided on the front and back layers, and at least one of the hard layers is exposed on the front surface or the back surface. A concrete form material impregnated with a water repellent such that no water repellent layer remains on at least one surface of the wood fiberboard.