JP2002194891A - Concrete placing form made of thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete placing form made of thermoplastic resin, remarkably lightweight with no recess caused by shrink of resin on the surface of a sheathing board part serving as a concrete placing face in spite of integrally forming plate-like ribs on the back side of the sheathing board part. SOLUTION: This concrete placing form made of thermoplastic resin is formed by integrally forming the sheathing board part whose front face serves as a concrete placing face, and the plate-like ribs provided on the back face of the sheathing board part. In this case, the surface part of the sheathing board part is composed of a skin layer, and the interior of the sheathing board part is composed of a foam body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a concrete casting formwork made of a thermoplastic resin.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a weir plate portion made entirely of a non-foamed thermoplastic resin and having a front surface serving as a concrete casting surface, and a plate-like rib provided on the back surface of the weir plate portion. There is known a concrete casting formwork in which is integrally formed. Since the concrete casting formwork is provided with plate-shaped ribs on the back surface of the weir plate portion, it has excellent strength and is relatively easy to assemble. However, a conventional thermoplastic resin casting concrete formwork is made of a non-foamed thermoplastic resin, and furthermore, a dam plate portion and a plate-like rib are integrally formed by an injection molding method, a hot press method, or the like. Therefore, a dent 8 due to the shrinkage of the resin is present on the surface of the weir plate portion where the plate-shaped rib is present on the back side, and the dent causes blistering on the surface of the poured concrete. To avoid this problem, if you make the plate-like rib thinner,
Since the required rigidity of the concrete casting formwork cannot be obtained, the present inventors have tried to increase the number of plate-shaped ribs in order to maintain the formwork rigidity. Sex has worsened.

[0003]

SUMMARY OF THE INVENTION Under such circumstances,
The present inventors have found that despite the fact that plate-like ribs are integrally formed on the back side of the weir plate portion, there is no dent due to resin sink on the surface of the weir plate portion serving as a concrete casting surface, and light weight As a result of studying a concrete casting mold made of a thermoplastic resin, the present invention has been accomplished.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a weir plate having a concrete casting surface on the front surface and a plate-like rib provided on the back surface of the weir plate portion are integrally formed. It is an object of the present invention to provide a concrete casting mold made of thermoplastic resin, wherein the surface of the plate portion is a skin layer and the inside of the weir plate portion is a foam. In the following description, the mold for casting concrete made of thermoplastic resin of the present invention will be simply referred to as “the mold of the present invention”.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The formwork of the present invention comprises a weir plate and plate-like ribs formed integrally with the weir plate on the back surface thereof. For example, as shown in FIG. 1 which is a schematic perspective view of a mold created in an embodiment which is one of the preferred embodiments of the mold of the present invention, the mold 1 of the present invention A plate-shaped rib (peripheral rib) 3 formed on the peripheral edge of the back surface, and a plate-shaped rib (parallel formed on the rear surface of the weir plate portion parallel to the side of the weir plate portion and having both ends connected to the outer peripheral rib 3) Reinforcing ribs) 4, 5
And can be composed of The plate-shaped rib provided on the back surface of the weir plate portion of the formwork of the present invention is usually provided on the peripheral edge portion of the back surface of the weir plate portion in order to strengthen the formwork and facilitate assembly of the forms. The main ribs are plate-shaped ribs (outer peripheral ribs), and reinforcing ribs are appropriately provided according to the strength required for the mold. The normal reinforcing rib is provided in parallel with the long side of the weir plate portion 2 like the rib 4 shown in FIG. 1 or on the short side of the weir plate portion 2 like the rib 5. Although they are provided in parallel or a combination thereof, they need not necessarily be formed in parallel with the sides of the weir plate portion. The number of reinforcing ribs is arbitrary, and is appropriately determined according to the desired strength of the mold.

Although the size of the weir plate portion is not particularly limited, generally a size of 300 mm as a unit length and an integer multiple of this unit length is often used. For example, a so-called 2 x 6 plate size of 600 mm short x 1800 mm long,
And so-called 3 × 6 of 900 mm short x 1800 mm long
The plate size is a common dimension of the formwork of the present invention. Also,
The weir plate portion is preferably thicker to more effectively prevent sink marks, but the thicker the product, the heavier the product and the longer the molding cycle.

[0007] The thicker the plate-shaped rib, the greater the reinforcing effect, but the heavier the product, the longer the molding cycle, and the more likely it is to sink. on the other hand,
The thinner the plate-like ribs, the more the occurrence of sink marks is suppressed and the lighter the product is, but the smaller the reinforcing effect is, and the more difficult the foaming becomes. Therefore, the thickness of the plate-like rib is usually 2 mm to 6 mm.
mm is preferable. In addition, it is preferable that the thickness of the root portion of the plate-like rib is larger than that of the tip portion in consideration of the releasability from the mold at the time of molding. It is preferable to provide a gradient of 1 to 2 degrees toward the center, and about 0.5 degrees in the practical minimum. However, the outer peripheral rib is usually formed so that the outer surface of the outer rib is perpendicular to the surface of the weir plate portion and the inner surface of the outer rib is tapered so that the molds can be easily assembled. .

[0008] In the formwork of the present invention, the surface of the weir plate portion has a skin.
Layer, and the inside of the weir plate portion is made of foam.
You. FIG. 2 is a schematic partial sectional view showing a few examples of the mold of the present invention.
Are shown in FIGS. Reference numeral 6 in the figure denotes a skin layer, and reference numeral 7 denotes
1 shows a foam. In the present invention, the skin layer₁/
ρ_Two> 0.909 [ρ₁: Apparent specific gravity of skin layer (g / c
m ^Three), Ρ_Two: Specific gravity of resin constituting skin layer (g / c
m^Three)] Is the layer that satisfies the formula
It is a layer that greatly contributes. ρ₁And ρ_TwoIs JIS K
It is a value measured according to the A method of 7112.

In the weir plate portion and the plate-like rib, the expansion ratio of the foam surrounded by the skin layer is determined in accordance with prevention of sink mark and weight reduction, and is usually preferably about 1.1 to 5 times. In addition, from the viewpoint of sink protection effect, lightening effect, rigidity and impact strength, the ratio of the thickness of the foam to the thickness is:
A range of 14 to 99.5% is desirable.

In the formwork of the present invention, the foam may be located only inside the weir plate portion as shown in FIG. 2, but the plate-like ribs have a surface layer made of a skin layer like the weir plate portion. Yes,
Preferably, the interior is a foam. The foam in the plate-like rib is preferably present in the entire region from the tip of the plate-like rib to the base of the plate-like rib as shown in FIG. Considering only prevention, the foam may be present only at the base of the plate-like rib as shown in FIG.

The total thickness of the weir plate portion and the plate-like ribs of the formwork of the present invention, ie, the thickness of the weir plate portion and the plate shape, so that the formwork of the present invention can be easily used together with the conventional plywood formwork. The total length of the ribs is preferably 50 mm to 80 mm. Specifically, the thickness of the conventional plywood formwork is generally 60 mm to 62 mm in the Kanto region and 70 mm to 72 mm in the Kansai region. The mold of the present invention set to the same value is extremely advantageous in practical use.

Examples of the thermoplastic resin constituting the mold of the present invention include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, acrylonitrile / butadiene / styrene copolymer (ABS resin), polyimide, polycarbonate and polyethylene terephthalate. Thermoplastic resins, modified products thereof, polymer alloys, and mixtures thereof. Polyolefins are preferred, and polypropylene is particularly preferred. It is preferable that the dam plate portion and the plate-like rib are made of the same material from the viewpoint of productivity and strength.

[0013] Such a thermoplastic resin may contain various additives such as a heat stabilizer and an ultraviolet ray inhibitor, and a coloring agent, if necessary. In addition, these resins may contain a reinforcing material such as a reinforcing fiber or an inorganic particle filler for improving the strength and the elastic modulus. Preferred reinforcing fibers include inorganic fibers such as glass fiber, carbon fiber, and alumina fiber and organic fibers such as Kepler, and inorganic fibers, particularly glass fibers, are particularly preferable. Reinforcement fiber length is 0.1m
The range is preferably from 50 to 50 mm, more preferably from 0.5 to 15 mm. Further, the fiber diameter is preferably in the range of 1 μm to 50 μm, and more preferably in the range of 1 μm to 20 μm.
Preferred inorganic particle fillers include whiskers such as potassium titanate, talc and wollastonite. In addition, only one kind of reinforcing material may be used, or two or more kinds may be used in combination. The amount of the reinforcing material used varies depending on the type thereof, but is generally preferably in the range of 5 to 50% by weight, more preferably in the range of 10 to 40% by weight of the entire thermoplastic resin composition. If the amount of reinforcing material is too small, a sufficient reinforcing effect cannot be obtained,
If the amount is too large, the molding of the mold may be hindered.

The method for producing the mold of the present invention is not particularly limited, and may be any ordinary thermoplastic resin molding method. For example, it can be produced by a hot press method. In the case of the hot press method, the thermoplastic resin containing a reinforcing material and a foaming agent such as a reinforcing fiber or an inorganic particle filler used as a raw material, the reinforcing material, the foaming agent and the thermoplastic resin at a melting temperature of the resin or higher. It is preferred to use a mixed melt. For example, the mold of the present invention can be manufactured by the following procedure. That is, a predetermined amount of a resin melt containing a foaming agent is injected into a mold and compressed so that the cavity clearance of the mold is less than the set thickness of the dam plate. Cool in the compressed state to form a skin layer on the surface layer, and then open the mold so that the cavity clearance of the mold becomes the set thickness of the weir plate, and foam the resin surrounded by the skin layer to form the skin. Form a foam inside the layer. Thus, the mold of the present invention is obtained. In the above method, a foam layer is easily formed inside the weir plate portion and the plate-like rib as the compression time is shorter,
The longer, the more difficult it is to form a foamed layer inside the plate-like rib.

As the foaming agent, any of a so-called physical foaming agent and a so-called chemical foaming agent can be applied, but a chemical foaming agent is preferably used. It is preferable to use a so-called decomposition type foaming agent as a chemical foaming agent, and to perform foaming using gas generated by decomposition of the foaming agent. Examples of the decomposable foaming agent include an inorganic foaming agent such as sodium bicarbonate and an organic foaming agent such as an azo foaming agent, a nitroso foaming agent, a hydrazide foaming agent and a triazine foaming agent. The amount of the foaming agent to be used is appropriately determined according to the type of the foaming agent so that a desired expansion ratio is achieved.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

A polypropylene pellet 1 containing 25% by weight of glass fiber having an average fiber length of 3 mm and a fiber diameter of 13 μm.
33 parts by weight of an azodicarbonamide foaming agent (trade name:
Cell microphone MB3062, manufactured by Sankyo Kasei Co., Ltd.) and 5 parts by weight of the mixture were supplied to a plasticizer, and the mixture was supplied to a plasticizer.
The mixture was melt-kneaded at ℃. On the other hand, a molding machine comprising a pair of male and female molds that can be opened and closed was prepared, and the temperature of the male and female molds was set to 45 ° C. Both male and female molds have a long length of 1800 mm, a short length of 600 mm, a thickness of a weir plate portion of 4 mm, and an outer rib height of 68 m.
m, reinforcement rib base width 4mm, taper angle of reinforcement rib:
It was designed to define a cavity clearance corresponding to a 0.5 degree mold. Further, a passage for supplying the molten resin between the male and female molds was provided in the female mold. The melt obtained by the melt-kneading was supplied through a passage in the female mold between the male and female molds opened so that the cavity clearance at the weir plate forming portion was 5 mm.

Thereafter, the mold is clamped at a mold clamping speed of 9.8 mm / sec until the cavity clearance in the dam plate forming section becomes 3 mm, and the pressure is applied at 92.6 kgf / cm ² for 1.5 seconds to press the dam plate. A skin layer was formed on the surface of the rib. Subsequently, the male and female molds were opened until the cavity clearance became 4 mm, and held for 50 seconds to form a foam. Thereafter, the mixture was cooled to obtain a thermoplastic concrete casting mold. The outline of the shape of the obtained mold is as shown in FIG. No dent was found on the surface of the weir plate near the outer peripheral ribs and the reinforcing ribs of the obtained mold.

[0019]

According to the present invention, dents are formed on the surface of the weir plate near the plate-like ribs even though the weir plate and the plate-like rib provided on the back surface thereof are integrally formed. And a formwork excellent in lightness is provided. When this form is used for placing concrete, the form is lightweight, so that the form is extremely easy to transport and assemble, and the cast concrete surface is smooth.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a preferred example of a thermoplastic resin casting concrete form of the present invention, and is a schematic perspective view of a form obtained in an example.

FIG. 2 is a schematic partial cross-sectional view of one example of a thermoplastic resin concrete casting formwork of the present invention.

FIG. 3 is a schematic partial cross-sectional view of another example of the thermoplastic resin concrete casting formwork of the present invention.

FIG. 4 is a schematic partial cross-sectional view of another example of the concrete casting mold made of thermoplastic resin of the present invention.

FIG. 5 is a schematic partial sectional view of a conventional thermoplastic resin casting concrete formwork.

[Explanation of symbols]

 1: concrete casting mold made of thermoplastic resin 2: dam plate 3: plate-like rib (outer peripheral rib) 4: plate-like rib (reinforcement rib) 5: plate-like rib (reinforcement rib) 6: skin layer 7: Foam 8: dent

Claims (4)

[Claims] 1. A dam plate having a front surface of a concrete casting surface and a plate-like rib provided on the back of the dam plate are integrally formed, and the surface of the dam plate is formed of a skin layer. And a concrete casting mold made of a thermoplastic resin, wherein the inside is a foam. 2. The concrete casting mold made of thermoplastic resin according to claim 1, wherein the surface of the plate-like rib is a skin layer and the inside of the plate-like rib is a foam. 3. The concrete casting formwork made of thermoplastic resin according to claim 1, wherein the plate-shaped ribs are formed on the peripheral edge of the back surface of the weir plate portion. 4. The concrete casting mold made of thermoplastic resin according to claim 1, which is made of a thermoplastic resin containing a reinforcing material.