JPH0640985U - Bulletin board - Google Patents

Abstract

(57) [Summary] [Purpose] Fixing force of thumbtack on bulletin board and cellophane tape,
Improve the adhesive strength of the duct tape. [Structure] Hard layers 1a and 1b having a higher specific gravity than the central layer 1
Is made of medium specific gravity fiberboard formed on the front and back parts, and is 3 to 15
Bulletin board with% waterproofing agent added. [Function] Unlike plywood, it consists of a medium specific gravity fiber board that is uniform over the entire thickness, and has a hard layer 1a on the surface, so it does not come off even if you insert a thumbtack, and cellophane and gum tape adhere well to the surface of the hard layer 1a. it can.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 A bulletin board for pasting posters and other posted objects on the surface.

[0002]

[Prior art and its problems]

 Conventionally, plywood is often used as a bulletin board because it is easy to handle and its price is low.In particular, since the bulletin board for elections has a short notice period, all plywood is used and nails are attached to the frame surface of the frame material. Used by fixing with wood screws.

A bulletin board can be easily pasted with a bulletin board by a thumbtack, cellophane tape, gum tape, glue, etc., and it is necessary that the bulletin board is sufficiently stuck and held in the event of wind and rain.

By the way, plywood is manufactured by laminating and bonding a plurality of veneers obtained by thinly cutting natural wood, and the problem of depletion of natural resources has been widely taken up in the world. It becomes difficult to cut down, and it is difficult to obtain good quality veneer due to the deterioration of the quality of raw wood, and it is difficult to obtain cheap and good quality and stable plywood.

It is common for plywood to use good quality veneer on the front and back and low quality veneer for the core. Even if there is no problem in appearance, the core part has hard knots, missing knots, cracks, etc. However, there is a problem that the thumbtack is hard to stick in the hard knot part, and the thumbtack is hard to stick in the cracked part.

Further, since the surface of the plywood has a conduit groove or the like and is a rough surface, not only is the cellophane tape or gum tape not sufficiently adhered, but also the glue easily penetrates into the plywood and the adhesive strength is not obtained. It has a problem such as.

[0007]

[Technical Means] A bulletin board made of medium specific gravity fiber plates having hard layers 1a and 1b having a higher specific gravity than the central layer 1 formed on the front and back portions, and to which a water resistant agent of 3 to 15% is added.

[0008]

[Action]

 Unlike plywood, it is made of a medium specific gravity fiber board that is uniform over the entire thickness, and has a hard layer 1a on the surface, so it does not come off even when a thumbtack is stabbed, and cellophane and gum tape can also adhere well to the surface of the hard layer 1a.

[0009]

[Description of configuration]

 The bulletin board of the present invention is made of medium specific gravity fiberboard. The medium specific gravity fiberboard has hard layers 1a and 1b having a thickness of 0.3 to 3 mm on the front and back sides, and an overall specific gravity including the center layer 1 of 0.4 to 0. 8 The hard layers 1a and 1b each have a layer thickness of 0.3 to 3 mm, preferably 0.5 to 2 mm, and the specific gravity of that portion is 0.8 to 1.4, preferably 1.0 to 1.2. It is a range.

Further, it is preferable that the hard layers 1 a and 1 b on the front and back sides have a specific gravity that is at least 0.1 or more, preferably 0.3 to 0.8 as compared with the specific gravity of the central layer 1.

As described above, the hard layers 1a and 1b, which have a higher specific gravity in the thickness direction than the central layer 1 and are excellent in tensile strength and compression strength, are arranged on the front and back portions, are lightweight, have a high bending strength, and are flexible against load. The amount of change is small.

The hard layers 1a and 1b are preferably exposed on the surface side as shown in FIG. 1, and the exposed surface is used as the surface of the bulletin board, and the layer thickness is 0.3 to 3 mm, The specific gravity is 0.8 to 1.4.

When the hard layers 1a and 1b have a layer thickness of 0.3 mm or less and a specific gravity of 0.8 or less, the pull-out resistance when the thumbtack is stabbed is low, and the hard layer is easily removed.

On the other hand, when the layer thickness is 3 mm or more and the specific gravity is 1.4 or more, the push-in of the thumbtack is hard and difficult.

In the bulletin board of the present invention, the hard layers 1a and 1b having a smooth surface and high water impermeability are exposed to the surface, so that the adhesion of the cellophane tape is improved, and the adhesive is less sucked in and the adhesion is improved.

If the specific gravity of the central layer 1 is 0.4 or less, sufficient strength as a plate cannot be obtained, and conversely, if it is 0.75 or more, the whole weight of the plate increases and it is difficult to handle.

If the difference in specific gravity between the hard layers 1 a, 1 b and the central layer 1 is 0.1 or less, it is sufficient if the thickness of the hard layers 1 a, 1 b provided on the front and back portions is not made equal to that of the central layer 1. Bending strength and deflection are not obtained, resulting in a heavy plate that is difficult to handle.

On the other hand, if the difference in specific gravity is 0.8 or more, a large difference occurs in the mechanical properties of the hard layers 1a, 1b and the central layer, and for example, in the case of bending load, the hard layers 1a, 1b are on the load side. In the central layer 1, the specific gravity is low and the compressive force acts on the counter-load side, and the tensile force acts on the non-load side, but the specific gravity is high and the wood fibers are dense and the compression and tensile deformation in the in-plane direction do not occur easily. Since the fibers are sparse, it is not preferable because delamination occurs between the hard layers 1a and 1b and the center layer 1 due to the difference that compression and tensile deformation easily occur.

Such hard layers 1a and 1b are used in the manufacturing process of the medium specific gravity fiberboard by setting the water content of the wood fibers located on the front and back sides to be high during heating and pressing, and by applying an adhesive to the wood fibers. By setting a large amount of addition, a layer having a higher specific gravity than the central layer 1 is locally formed.

Since the obtained medium specific gravity fiber board has a low specific gravity thin surface layer due to precure of the adhesive at the time of heating and pressing, the hard layers 1a and 1b are exposed by sanding. Further, the water impermeable layer 2 is formed on the exposed hard layers 1a and 1b as required as shown in FIG.

The water impermeable layer 2 is formed by sticking impregnated paper obtained by impregnating paper with a synthetic resin with an adhesive. Alternatively, a synthetic resin paint is applied and dried to form a synthetic resin film.

The synthetic resin coating may be formed in multiple layers. Since the water-impermeable layer 2 is formed on the exposed hard layer, the water-impermeable layer 2 has excellent adhesion and adhesion, and is provided without peeling. By providing the water impermeable layer 2, the adhesion of cellophane tape, gum tape, etc. is improved, and the adhesive strength is improved without the inhalation of glue.

A water resistant agent 4 of 3 to 15% is added to the inside of the medium specific gravity fiber board. The water resistant agent 4 is rosin, wax, paraffin or the like, and suppresses moisture absorption and water absorption to improve the durability of the medium specific gravity fiber board as a bulletin board.

In the bulletin board of the present invention, for example, in a manufacturing process of a wood fiberboard by a dry method, the wood fibers that have been defibrated and added with an adhesive or the like are dried and stacked on a screen conveyor by a forming device and temporarily pressed. Thus, a wood fiber mat is obtained. Then, a medium-density fiber board obtained by heating and pressing a standard length mat cut into a certain size is used.

Increasing the amount of the adhesive added, and water-retaining non-woven fabric, paper, cloth, etc., in which water is applied to the upper surface and / or lower surface of the standard mat obtained in the same manner as described above or water is contained. By placing a sheet-like material with heat and pressing it, the hard layers 1a and 1b can be thickened because they are heated and pressed while the water content on the front and back surfaces is increased. Further, the water resistant agent 4 may be added at the same time when the adhesive is added.

[0026]

[Effects of the Invention] a The bulletin board of the present invention is composed of a medium specific gravity fiberboard obtained by defibrating wood fibers, and is obtained by crushing and defibrating defective raw wood waste, etc. Use is measured.

B Medium specific gravity fiberboard is an industrialized product, and a homogeneous one can be stably obtained. Further, since the hard layers 1a and 1b having a high specific gravity of 3 to 3 mm and having a high specific gravity are provided on the front and back portions and at least one of the hard layers 1a is exposed and the exposed hard layer 1a is used as the surface, the pushpin of the thumbtack is used. It can be easily inserted, has high pull-out resistance, does not come off easily, has a smooth flat surface, and can provide adhesion to cellophane tape, gum tape, etc., and because the hard layers 1a, 1b are impermeable to water, it also absorbs glue. It can be prevented and the adhesive strength of the glue can be sufficiently obtained, so that the sticking and holding of posters and other posted objects can be done without problems.

C By providing the water impermeable layer 2 on the surface of the hard layer 1a, the sticking and holding property is further improved.

Since the water resistant agent 4 of d 3 to 15% is added, moisture absorption and water absorption are suppressed, so that the durability of the display board is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of the bulletin board of the present invention,

FIG. 2 is a cross-sectional view of a case where a water impermeable layer 2 is provided on the front surface side,

[Explanation of symbols]

1: central layer, 1a, 1b: hard layer, 2: impermeable layer, 3:
Water resistant agent.

Claims (3)

[Scope of utility model registration request] 1. A hard layer 1 having a higher specific gravity than that of the central layer 1.
A and 1b are medium specific gravity fiberboards formed on the front and back parts, and a water resistant agent of 3 to 15% is added thereto. 2. The bulletin board according to claim 1, wherein at least the hard layer 1a on the front surface side is exposed on the surface of the medium specific gravity fiberboard. 3. The bulletin board according to claim 1, wherein the water impermeable layer 2 is formed on the surface side of the medium specific gravity fiberboard.