JPH10180735A - Concrete form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concrete form having high durability which can be used repeatedly in which a concrete has a sufficient strength and fine external appearance free from pits (trace of blister). SOLUTION: In the concrete form, a sheath-core type composite long fibers, in which thermoplastic synthetic polymers having melting point 40 deg.C higher than that of a sheath portion are disposed in a core portion, serve as constituent fibers, and a part or the whole of the constituent fibers are bundled together by being fused to form a non-woven fabric layer and a synthetic resin layer having water permeability of 20g/m<2> or more is provided on one side of the non-woven fabric layer. It is preferable that a part or the whole of the constituent a fiber structure of the non-woven fabric layer has a three-dimensional intermingled structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete formwork having a water absorption / drainage performance used when placing concrete or mortar.

[0002]

2. Description of the Related Art At the time of placing concrete, plywood logs are used. This plywood is transported from timber exporting countries such as Southeast Asia and Canada to Japan, where it is processed and used. However, today, it is said that the deforestation has an adverse effect on the flora and fauna of the area and the occurrence of disasters, and from the standpoint of protecting the global environment, excessive use of raw wood must be avoided.

[0003] When only plywood is used, excess water in concrete is generated at the interface between the plywood and concrete when concrete is poured. Due to the water bubbles, an avatar (water bubble mark) of a crater-like concave portion was generated on the concrete surface, and a phenomenon that the strength of the concrete became weak occurred.

[0004] In view of the above problem, by using a concrete formwork attached to the surface of the plywood instead of the plywood, it is possible to gradually drain the excess water in the concrete generated at the time of placing the concrete. The occurrence of avatars as described above can be suppressed, and the phenomenon that the surface strength of concrete becomes weak can be prevented.

[0005] Today, various proposals have been made for a concrete form used in place of plywood by sticking to the surface of plywood. For example, JP-A-1-190410 and JP-A-63-306003 propose that a concrete mold has a specific fiber structure density of a nonwoven fabric to avoid avatars. Patent registration No. 1693
No. 259, a smooth surface layer with no fluff, an intermediate layer in which fibers constituting the surface and another base cloth are integrated by needle punch, and fibers constituting the surface emerge from the intermediate layer to the back surface. A three-layer structure having a back surface layer is proposed. Japanese Utility Model Laid-Open No. 1-67244 proposes a non-woven fiber layer in the form of a breathable film having pores on the surface.

[0006]

According to the above-mentioned technique proposed in the prior art, the surface layer (the side in contact with the concrete surface) is made of fibers, and the fiber structure is devised to improve the fiber density. By adjusting the value of ア, consideration is given to the prevention of avatars and the ease with which concrete is removed from concrete after casting.

However, the above-mentioned ones are not enough to prevent the occurrence of avatars, that is, to adjust the air permeability, and to satisfy the conflicting physical properties of penetration of the concrete solution into the sheet during casting.

More specifically, to prevent the occurrence of avatars, it is sufficient to increase the air permeability to some extent. However, when the air permeability is increased, the concrete solution and the excess water in the concrete enter the concrete formwork. . When the concrete form is separated from the concrete surface after the casting, the concrete that has entered the concrete form is hardened, and it is difficult to remove the concrete. In addition, the concrete form after peeling has fluff at its part or concrete remains partially, and it becomes more difficult to separate when reused, and the structural form of the concrete form such as tearing occurs. , The number of reuses is limited.

On the other hand, in order to prevent the above-mentioned problem from occurring, the method of increasing the fiber density in the cross section of the concrete form to limit the air permeability also causes avatars on the concrete surface.
The original role of the concrete formwork,
It is difficult to achieve the hardness and aesthetic appearance of the concrete surface.

As described above, when a material such as fiber is used as the material of the concrete form as compared with concrete ceramic, both prevention of avatar generation and detachment of concrete after casting are satisfied, and It is difficult to ensure sufficient durability of the concrete formwork.

In view of the above-mentioned conventional background, an object of the present invention is to efficiently discharge surplus moisture existing in concrete and to provide a clean appearance free of avatars (water bubble marks) on the concrete surface after casting. It is an object of the present invention to provide a durable concrete form which can obtain concrete having a high strength and can be used repeatedly.

[0012]

SUMMARY OF THE INVENTION The present invention achieves the above-mentioned object, and mainly has a structure in which a core is provided at a distance of 4 mm from a sheath.
A core-sheath type composite long fiber comprising a thermoplastic synthetic polymer having a high melting point of 0 ° C. as a constituent fiber, and a nonwoven fabric layer in which a part or the whole of the constituent fiber is bound together by fusion,
20 g / water-permeable provided on one side of the nonwoven fabric layer
The concrete form, characterized in that it consists of a m ² or more synthetic resin layer in which the gist.

[0013] Further, in the above invention, a concrete form is characterized in that a part or the whole of the fiber structure constituting the nonwoven fabric layer has a three-dimensional entangled structure.

[0014]

Embodiments of the present invention will be described below. In the present invention, after placing concrete,
Considering that stress is applied to the form when the concrete form is detached from the concrete, and that the durability of the form is increased so that the plywood can be used many times, mainly the core is 40 ° C. from the sheath. A core-sheath type composite long fiber comprising a thermoplastic synthetic polymer having a high melting point is used as a constituent fiber, and a nonwoven fabric is used in which a part or the whole of the constituent fiber is bound together by fusion.

By setting the difference between the melting point of the core and the sheath of the core-sheath type composite filament at 40 ° C. or more, the nonwoven web is heat-treated at a temperature not less than the melting point of the sheath component and not more than the melting point of the core component. At the time of applying, the sheath portion is partially melted at least at the fiber intersection, and the long-fiber non-woven web constituting fibers are stitch-bonded to each other by fusion of the sheath portion, thereby maintaining the shape of the non-woven web and inter-fiber mutual. Can be united. On the other hand, the core can maintain the fiber structure without thermal deterioration, maintain the strength as a fiber, and maintain the mechanical strength as a nonwoven fabric. If the difference between the melting points of the core and the sheath is less than 40 ° C., during the heat treatment, even the components constituting the core are heat-melted or thermally degraded, resulting in a non-woven fabric having poor mechanical strength. Not preferred.

In the fusion structure in which the constituent fibers of the nonwoven fabric are partially or wholly bound by fusion, the nonwoven fabric does not fluff or break when detached after the concrete is cast. Also, since each fiber constituting the nonwoven fabric is fused to part or the whole, the nonwoven fabric structure itself becomes stable and can withstand external stress, preventing the constituent fiber groups from falling apart, The principle is that durability is improved.

The composite ratio of the core portion and the sheath portion of the core-sheath type composite continuous fiber is preferably in the range of 80 to 20% by weight of the sheath portion to 20 to 80% by weight of the core portion. If the composite ratio of the sheath is less than 20% by weight, a nonwoven fabric having excellent mechanical strength is obtained, but the adhesive strength between constituent fibers of the nonwoven fabric obtained by the heat treatment is reduced, and the shape retention of the nonwoven fabric and the fiber Tend to have poor cohesion. On the other hand, if it exceeds 80% by weight, the mechanical strength of the fiber tends to be inferior although the adhesive strength is excellent, and it is difficult to obtain a nonwoven fabric having a high mechanical strength. . In consideration of the above reasons and the stability of the fiber cross section, a more preferable composite ratio (core / sheath) of the core and the sheath is 40 to 60 /
It is in the range of 60 to 40% by weight.

The thermoplastic polymer used in the core-sheath type conjugate fiber includes polyester, polyester copolymer, and the like.
Nylon, polypropylene such as nylon copolymer, polyethylene, and copolymers thereof, and the like.

The combination of the polymer of the core portion and the polymer of the sheath portion is preferably one having adhesiveness to each other. As a specific combination, a core / sheath type structure of polyester / copolyester using polyethylene terephthalate as the core polymer and polyethylene terephthalate copolymer as the sheath polymer, nylon-46 as the core polymer, sheath Nylon / nylon core-sheath type structure using nylon-6 as the polymer of the part, polyethylene terephthalate as the polymer of the core,
Polyester / polyolefin core-sheath type structure using polyethylene or the like as a sheath polymer, and nylon / polyolefin core-sheath type using nylon-6 as a core polymer and polyethylene as a sheath polymer. There are structures.

Of these combinations, it is preferable to use a polyethylene terephthalate-based polymer as the core polymer from the viewpoint of tensile strength of the nonwoven fabric and productivity. Further, as the sheath, it is preferable to use an olefin polymer having high alkali resistance since concrete is alkaline.

A method of subjecting a long-fiber nonwoven web to heat treatment at a temperature equal to or higher than the melting point of the sheath component and equal to or lower than the melting point of the core component to form a fused structure in which part or all of the constituent fibers are bound together by fusion is as follows. Examples of the method include a method of passing between heating rolls, a method of following the heating roll, and a method of passing the heating region in a non-contact manner.

The basis weight of the nonwoven fabric layer used in the present invention is 200
g / m ² or more. When the basis weight of the nonwoven fabric layer is less than 200 g / m ² , when the concrete formwork is repeatedly used, it tends to be broken, the number of times of reuse is limited, and the durability tends to be poor. The upper limit of the basis weight of the nonwoven fabric layer is not particularly limited.
g / m ² is sufficient.

As the nonwoven fabric layer used in the present invention, any one may be used as long as the core-sheath composite long fiber is a main constituent fiber. For example, a nonwoven fabric composed of only a core-sheath composite long fiber, a nonwoven fabric obtained by blending and spinning a core-sheath composite long fiber and other long fibers, a nonwoven fabric mainly composed of a core-sheath composite long fiber, and other nonwoven fabrics ( Long fiber non-woven fabric,
Short fiber nonwoven fabric, etc.), and a composite nonwoven fabric compounded by entanglement or fusion may be appropriately selected according to the purpose.

In the nonwoven fabric layer, it is preferable to form a high-density structure between the constituent fibers on the side on which the synthetic resin layer is provided, since it is easy to apply uniformly when the synthetic resin layer is provided. Also,
Even if the synthetic resin layer is partially uneven due to a coating error, the formation of the high-density structure between the constituent fibers can also suppress the penetration of concrete particles into the nonwoven fabric layer.

In the nonwoven fabric layer, as a method of forming a high-density structure between the constituent fibers on the side on which the synthetic resin layer is provided, when the nonwoven fabric layer is composed only of the core-sheath composite fiber, heat treatment is performed on one side only. Can be achieved. In addition, the nonwoven fabric layer is formed by laminating a nonwoven fabric having only the core-sheath composite fiber as a constituent fiber and another nonwoven fabric (which is a fiber composed of only a polymer alone having a temperature higher than the sheath component by 40 ° C. or more) as a constituent fiber.
When it is composed of a layer, it can be achieved by heat-treating the nonwoven fabric having only the core-sheath type composite fiber as a constituent fiber.

In the present invention, when a part or the whole of the fiber structure constituting the nonwoven fabric layer has a three-dimensional entangled structure, the excess water can be discharged more effectively when discharging the surplus water of the concrete. Here, the three-dimensional entangled structure means that the fibers constituting the nonwoven fabric are entangled not only in the lateral direction (two-dimensional) but also in the thickness direction (three-dimensional), and the constituent fibers are randomly distributed in each direction. It refers to a structure in which a simple arrangement is formed and integrated.

In order to make a part or the whole of the fiber structure constituting the nonwoven fabric layer into a three-dimensional entangled structure, the nonwoven web before heat treatment is obtained by subjecting the nonwoven web to needle punching, water jet needle punching, or the like. be able to.

The above-mentioned non-woven fabric layer retains the form of a synthetic resin layer provided on the side in contact with the concrete surface described later, and is generated from the concrete solution during casting and enters the non-woven fabric layer through the synthetic resin layer. It plays a role in efficiently discharging surplus water.

The concrete formwork of the present invention is provided with a synthetic resin layer having water permeability and at least 20 g / m ² on one side of the nonwoven fabric layer (the side in contact with concrete).

By providing the synthetic resin layer, the concrete surface and the non-woven fabric layer composed of the fibers are separated from each other so that they do not come into contact with each other, thereby preventing concrete particles during casting from entering the non-woven fabric layer. In this way, only the surplus concrete can enter. Then, only the concrete excess water can be passed through the synthetic resin layer and discharged through the nonwoven fabric layer. Further, when the concrete form is separated from the concrete surface after the casting, only the synthetic resin layer is in contact with the concrete surface, so that it can be easily peeled off. Therefore, since the concrete formwork is not damaged when peeled, it can be used repeatedly. On the other hand, the concrete obtained after removing the formwork has a clean appearance without avatars (water bubble marks) on the surface and a sufficient surface strength.

The synthetic resin layer provided on one side of the nonwoven fabric layer
At least 20 g / m2 in form weight ^TwoAnd Synthetic resin
20 g / m layer^TwoIf less than, coating unevenness is likely to occur.
And one side of the non-woven fabric is sufficiently covered with a synthetic resin layer
Parts that do not exist. Then, Concree
And completely separate the non-woven fabric layer from contact
Concrete particles can enter the nonwoven fabric layer
The problem is that the concrete surface
When the mold material is released from the
Harden, making it difficult to separate, workability and concrete
It is not preferable because the durability of the mold cannot be improved.

Examples of the synthetic resin used in the present invention include vinyl acetate-based, polyethylene-based, and polypropylene-based synthetic resins.

As a method of providing a synthetic resin layer on the surface of the nonwoven fabric, particles of the synthetic resin are dispersed on the surface of the nonwoven fabric, and the synthetic resin is melted by heat and simultaneously fixed to the surface of the nonwoven fabric.
Powder processing method for imparting water permeability, a method of mixing inorganic or granular materials having a microporous structure with thermoplastic or thermosetting or a mixture of these to uniformly coat the surface of the nonwoven fabric, water-soluble or solvent-soluble After uniformly applying the substance to thermoplastic or thermosetting or a mixture of these to the non-woven fabric, removing the water-soluble or solvent-based substance to make the synthetic resin layer a microporous structure to give water permeability, etc. Is mentioned.

In the synthetic resin layer obtained by the above method or the like,
The micropores are distributed as if scattered on the surface and inside of the layer, and at least a part thereof is continuously and intermittently connected to each other. That is, a part of the micropores is continuous with the pores, and the micropores in the layer surface and the inside of the layer are connected as a whole, and have air permeability or water absorption. The diameter of the fine holes is preferably 0.1 to 10 μm. If it is less than 0.1 μm, the effect of passing and discharging surplus water in concrete is likely to be reduced, while 10 μm
If it exceeds, intrusion of the concrete particles into the nonwoven fabric layer cannot be prevented, which is not preferable.

[0035]

【Example】

Example 1 A core-in-sheath composite having a core-in-sheath composite ratio of 1 to 1 (weight ratio) in which polyethylene terephthalate is provided in a core portion and polyethylene in a sheath portion, and a composite filament having a single-filament fineness of 3 denier are randomly dispersed.
After forming a nonwoven web having a basis weight of 300 g / m ² , needle punching was performed, one side of the nonwoven web was placed along a roll surface of a heat calender (temperature: 120 ° C.), and a high-density structure was formed between the constituent fibers on one side. The fibers were fused together smoothly and as a whole. Further, particles of polyethylene were 80 g / m ² (Experimental Example A), 50 g / m ² (Experimental Example B), 30 g / m ² (Experimental Example C), and 20 g / m ² on the surface having a high density structure between constituent fibers. m ² (Experimental Example D), and the polyethylene particles were heat-treated at a temperature of 120 ° C. in an atmosphere, and the surface of the nonwoven fabric was powder-processed to 80 g / m ² (Experimental Example A) and 50 g / m ² (Experimental Example B). ), 30 g / m
² (Experimental example C) and a concrete form having a synthetic resin layer of 20 g / m ² (Experimental example D) were obtained.

These concrete forms were stuck to plywood, and a concrete solution was poured at an angle of 45 °, which is a condition under which avatars are likely to occur. One week later, when the concrete forms were released, the respective forms could be easily released from the concrete, and all the obtained concrete surfaces had no avatar.

Next, the above four types of concrete forms are stuck on plywood, and an angle of 45.degree.
A concrete solution was poured into the sample, and the experiment was repeated. 20
The mold having a synthetic resin layer of g / m 2 (Experimental Example D)
At the second time, detachment from the concrete surface became a little difficult.
The use of the second repetition was not possible. On the other hand, a mold having a synthetic resin layer having a basis weight of 30 g / m 2 or more (Experimental Example A
-C) could be used repeatedly 5 times, each form could be easily separated from concrete in all 5 times, and all the obtained concrete surfaces had no avatar.

Example 2 A core-sheath composite having a core-sheath composite ratio of 1 to 1 (weight ratio) in which polyethylene terephthalate is disposed in a core portion and polyethylene in a sheath portion, and a composite filament having a denier of single denier of 3 denier were randomly dispersed. Thereafter, a needle-punched non-woven fabric having a basis weight of 200 g / m ² and a core-sheath composite long fiber made of the same polymer as described above and having a single-filament fineness of 3 denier, and partially heat-compressed A partially thermocompression bonded nonwoven fabric of 100 g / m ² is bonded with heat at 120 ° C., and a water-soluble binder in which fine particles having a microporous structure are mixed with an acrylic resin is applied to the mirror surface of the partially thermocompression bonded nonwoven fabric in a foam form. And 5
A concrete form having a synthetic resin layer of 0 g / m ² was obtained.

Using the obtained concrete form, it was stuck on a plywood in the same manner as in Example 1, and a concrete solution was poured at an angle of 45 °, which is a condition under which avatars are likely to occur. One week later, when the concrete form was released, the form could be easily released from the concrete, and there was no avatar on the obtained concrete surface.

When a repetitive experiment was conducted in the same manner as in Example 1, five repetitions could be used.

Example 3 A core / sheath composite having a core / sheath composite ratio of 1 to 1 (weight ratio) in which polyethylene terephthalate is provided in the core and polyethylene in the sheath, and a composite filament having a denier of single denier of 3 denier 150 g / m2
^{2 and} a non-woven web made of polyethylene terephthalate and having a single-filament fineness of 3 denier and a fiber length of 150 g /
laminating a nonwoven web m ^2, core-sheath type composite nonwoven web side consisting of fiber to obtain a laminated nonwoven fabric subjected to a needle punching process so as to penetrate the side of the needle. Next, the nonwoven web composed of the core-sheath type composite fiber of the laminated nonwoven fabric is arranged along the roll surface of a heat calender (temperature: 120 ° C.) to form a high-density structure between the constituent fibers, and to smooth the fibers as a whole. The two were fused together.

Polyethylene particles were sprayed on the nonwoven web of the core-sheath type composite fiber of the laminated nonwoven fabric, and a concrete having a 60 g / m ² synthetic resin layer was formed by a powdering method in the same manner as in Example 1. Formwork was obtained.

Using the obtained concrete form, it was stuck to a plywood in the same manner as in Example 1, and a concrete solution was poured at an angle of 45 °, which is a condition under which avatars are easily generated. One week later, when the concrete form was released, the form could be easily released from the concrete, and there was no avatar on the obtained concrete surface.

When a repetitive experiment was conducted in the same manner as in Example 1, five repetitions could be used.

[0045]

As described above, according to the present invention, when casting concrete or mortar, excess moisture existing in concrete is efficiently sucked up by the synthetic resin layer having air permeability or water absorption, and the non-woven fabric layer is formed. The concrete surface after casting is free from avatars (water bubble marks), and concrete having a clean surface and strength can be obtained. On the other hand, concrete is only in contact with the synthetic resin layer of the concrete form, so when the concrete form is peeled from the concrete, it can be easily peeled off, and the durability of the concrete form is maintained. can do.

In addition to preventing the occurrence of avatars due to the discharge of excess water from the concrete and finishing the surface beautifully, the nonwoven fabric layer allows excess water to be efficiently discharged without leaving excess water in the concrete. The hardness is increased and the durability of the concrete itself is improved. Furthermore, since the nonwoven fabric having a fused structure withstands the stress when the concrete form is peeled from the concrete and has high durability, the durability of the concrete form is improved, and the number of times of using the plywood is increased. It can also prevent heavy logging of timber that deteriorates the natural environment.

Further, by providing the air-permeable or water-absorbing synthetic resin layer, the concrete surface and the non-woven fabric layer surface are separated from each other, so that the durability of the non-woven fabric layer and the concrete formwork are further improved, and the same effect as described above is obtained. Is obtained.

Claims (2)

[Claims] A core-sheath type composite continuous fiber comprising a core and a thermoplastic synthetic polymer having a melting point higher by 40 ° C. than that of a sheath part is mainly used as a constituent fiber, and a part or the whole of the constituent fiber is fused. A concrete formwork comprising a nonwoven fabric layer bound together and a synthetic resin layer having water permeability of 20 g / m ² or more provided on one surface of the nonwoven fabric layer. 2. The concrete formwork according to claim 1, wherein a part or the whole of the constituent fiber structure of the nonwoven fabric layer has a three-dimensional entangled structure.