JPH05162111A - Polyolefin resin composition for concrete decorative form - Google Patents

Abstract

PURPOSE:To provide a composition which can be separated easily from concrete and can be used repeatedly and further can be applied to a sufficiently strong concrete decorative form, wherein changes in dimension due to expansion and contraction of the form caused by temperature changes and the like can be restrained as much as possible. CONSTITUTION:In a polyolefin resin composition suitable for forming a concrete decorative form wherein a surface plate provided with a recess to represent an appearance having a pattern such as stone masonry and the like on the surface of cast concrete is provided, said composition includes filler of 5-55wt.% and its coefficient of linear expansion is less than 7X10<-5>/ deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition for a concrete decorative formwork, and more specifically, a masonry pattern on a retaining wall for river revetment, road improvement, residential land development, steep slope collapse countermeasures, etc. The present invention relates to a polyolefin resin composition for a concrete decorative form suitable for concrete construction for forming.

[0002]

2. Description of the Related Art Conventionally, a retaining wall for various civil engineering works and flood control works is often constructed with concrete from the viewpoint of durability, material cost, construction cost and the like. However, in recent years, from the viewpoints of harmony with the natural environment and ensuring a comfortable living environment, the surface of concrete, which is inorganic and has an artificial appearance, has a tendency to be shunned. A method of constructing concrete with a patterned appearance has been developed. Examples of such a construction method and a formwork used for this are, for example, JP-A-63-63
Many proposals have already been made, such as Japanese Patent Publication No. 147606, Japanese Patent Application Laid-Open No. 63-107512 and Japanese Utility Model Laid-Open No. 1-76203. Each of these proposed techniques has, as its basic configuration, a concave portion 2 having a pattern appearance such as a masonry and a convex portion 3 corresponding to a joint portion on one surface of a foam made of synthetic resin as shown in FIG. However, the mold 1 of the type in which the back surface is attached to a steel or wooden panel with an adhesive or the like is used.

By the way, when concrete is poured into a mold as described above and cured, synthetic resin foam such as expanded polystyrene generally tends to adhere to the concrete side. It takes a lot of time to remove it, and it is difficult to treat the residual material. Moreover, since the synthetic resin foam adheres to the concrete side as described above, the formwork is discarded after one use, which is extremely uneconomical. On the other hand, by preparing a mold having a convex portion corresponding to the concave portion and the joint portion, by performing various molding of synthetic resin using this, a synthetic resin molded body having a desired appearance can be obtained, It is possible to achieve the intended purpose by adhering it to a steel panel and connecting it to each other. However, such a synthetic resin generally has a different expansion / contraction rate from the steel panel, so that the expansion and contraction of the synthetic resin form, that is, the dimensional change occurs due to the temperature change after placing concrete, or the difference in temperature, etc. Since this is so large, various inconveniences such as a gap being formed in the mold or distortion on the entire surface of the mold occur, making it unusable as a mold. Therefore, it is conceivable to prepare a slightly larger or smaller formwork according to the season, but this is too complicated and not practical. As mentioned above,
Forming a mold using a mold using an ordinary synthetic resin has problems in terms of expansion and contraction, and its solution has been desired.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a concrete decorative form that has good peelability from concrete, withstands repeated use, and has sufficient strength. It is intended to provide a polyolefin-based resin composition capable of suppressing the dimensional change due to the expansion and contraction of the associated mold as much as possible.

[0005]

The present invention has been made to solve the above problems, and the gist of the present invention is to provide a concave portion expressing an appearance having a pattern such as masonry on the surface of the cast concrete. A polyolefin-based resin composition suitable for molding a concrete decorative formwork provided with a surface plate provided with, the resin composition containing 5 to 55% by weight of a filler, and having a linear expansion coefficient of 7 × 10 ^{−. A} polyolefin-based resin composition for concrete decorative formwork, characterized in that it is smaller than ⁵ / ° C.

The present invention will be described in detail below. First, in the present invention, the polyolefin-based resin refers to a known polyolefin-based resin, and as typical ones, polyethylene, polypropylene, polybutene, etc. are known, and modified products thereof are also included therein. It is a thing. In this case, the polyolefin resin is selected as the resin in the present invention, when these are used for the concrete formwork, the friction coefficient is small and the surface becomes smooth, so that the peelability from the cast concrete is improved, This is because demolding becomes easy. Next, the filler in the present invention includes glass fibers, rock wool, crushed mineral fibers typified by ceramic fibers, or inorganic fibers such as carbon fibers, talc, mica, glass powder or spheres, silica, calcined alumina. , Inorganic fillers such as calcium carbonate, and further, one kind or a combination of two or more kinds such as various whiskers.

In the present invention, 5 to 55% by weight of such a filler is blended with the above-mentioned polyolefin resin to obtain a resin composition. With this, the moldability and appearance of the mold to be molded are improved, It is possible to expect effects such as high specific gravity and reduction of linear expansion coefficient. In this case, if the content of the filler is less than 5% by weight, it is not sufficient to exert the above effects. On the other hand, even if the content of the filler exceeds 55% by weight, the above effect is saturated and no improvement in properties commensurate with the amount added is recognized, and rather, moldability is difficult. The upper limit of the filler content was 55% by weight. The linear expansion coefficient of the polyolefin resin composition thus constituted needs to be smaller than 7 × 10 ⁻⁵ / ° C.

When the coefficient of thermal expansion of the resin composition is larger than 7 × 10 ^-5 , when the working temperature is high, the decorative frame expands to form a large void between the steel panel and the backing. Occurs, or the joint between the steel panel and the decorative frame is left at high temperature, the joint part is damaged, and when the operating temperature is low, there is a gap between the decorative form and the decorative form. This causes inconveniences such as the generation of concrete and the flow of concrete. That is, when the coefficient of thermal expansion of the resin composition is larger than 7 × 10 ⁻⁵ , the expansion and contraction of the concrete decorative frame formed of the resin composition due to the temperature change become large, and the above-mentioned inconvenience occurs. The thermal expansion coefficient of this resin composition is 7 ×
It is critical that it is smaller than 10 ⁻⁵ for the above reason, and it is preferably 5.5 × 10 ⁻⁵ or less. The resin composition of the present invention may further contain one or more dyes / pigments, stabilizers, antioxidants, ultraviolet absorbers, plasticizers and other additives, if necessary.

Next, in the present invention, a concrete decorative formwork provided with a surface plate provided with a concave portion expressing the appearance having a pattern such as a masonry on the surface of the cast concrete using such a polyolefin resin composition. As a molding means, known molding methods such as blow molding and thermoforming (vacuum molding) can be used. In this case, regardless of which molding means is used, the concrete placing surface side is provided with a surface plate having a recess for expressing the appearance having a pattern such as a masonry on the surface of the cast concrete. Is done. When the molding is carried out by blow molding means, blow molding is carried out by a conventional method using a mold in which at least one surface of the mold is provided with a convex portion corresponding to the above-mentioned masonry pattern, and a pattern such as masonry is formed. A hollow formwork having a side wall on the outer periphery of a surface plate provided with a concave portion expressing the appearance thereof and further having a bottom plate at the lower end of the side wall is integrally molded, and the surface plate of the formwork is Blow
It constitutes the recess of the molded hollow mold. When the molding is performed by thermoforming (vacuum forming) means, the polyolefin resin composition of the present invention is formed into a sheet by a known means in advance, and the appearance having the above-mentioned masonry pattern is poured into the concrete. A mold is formed by thermoforming the sheet with a mold for forming a recess to be expressed on the surface, and the surface plate of the form constitutes the recess of the thermoformed mold. ..

[0010]

EXAMPLES The present invention will be described in more detail with reference to examples. According to the test method described in ASTM D-1238, polypropylene (A) having a melt flow index of 0.5 g / 10 min measured under conditions of 230 ° C. and 2160 g load, and melt flow index measured under the conditions of 190 ° C. and 2160 g also 0.5g / 10m
in low density polyethylene (B), polypropylene modified with maleic anhydride (maleic anhydride content of 0.
12%) (C), fiber diameter 13μ, strand length 3 mm,
Each compound shown in Table 1 was extruded at a temperature of 200 to 220 ° C. by a 40 mmφ vented-shaft extruder using glass fiber (D) using an epoxysilane-based sizing agent and talc (E) having an average particle size of 8 to 10 μm. Pellets were produced. The linear expansion coefficient of the material is 0 ° C according to ASTM D-696.
It was measured in the range of -50 ° C.

For Examples 1 to 4, using the compounds having the respective compositions shown in Table 1, concrete formwork having a masonry pattern was prepared by blow molding. Using this formwork, concrete walls were placed at low temperature (temperature 6 ° C.) and high temperature (temperature 33 ° C.) respectively, but there was no problem in construction. No resin was found to adhere to the concrete when the form was removed after the concrete had hardened, and the form was reusable. Also in Example 5, the compound having the composition shown in Table 1 was formed into a sheet having a thickness of 5 mm by a 65 mmφ single screw extruder, and further formed into a concrete formwork having a masonry pattern by vacuum forming. A concrete wall was placed using this form, but there was no hindrance to the placement at both low temperature (temperature 6 ° C) and high temperature (temperature 33 ° C). Further, when the mold was removed after hardening the concrete, the resin did not adhere to the concrete, and the mold was reusable.

[0012]

[Table 1] (Note) The numerical values of the composition indicate parts by weight.

As shown in Table 1 for Comparative Example 1, PP
A concrete formwork of the same type as in Examples 1 to 4 was formed by blow molding using only the above. When using this formwork, concrete molds were placed at low temperature (temperature 6 ° C) and high temperature (temperature 33 ° C), respectively. At low temperature, concrete exudes from around the formwork, which is inconvenient. It was Also in Comparative Example 2, as shown in Table 1, a concrete form was molded by blow molding in the same manner as in Examples 1 to 4 using a material composed of 80 parts by weight of ABS resin and 20 parts by weight of talc. There was no problem in workability at low and high temperatures, but it took time to remove the formwork after the concrete hardened, and concrete adhered to the formwork side. For reuse, it takes a lot of time to remove concrete from the formwork, which is inconvenient.

[0014]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a polyolefin resin composition having a low linear expansion coefficient in which dimensional changes due to expansion and contraction of a mold due to temperature changes and the like are suppressed as much as possible. This makes it possible to obtain a concrete decorative formwork that has not only the desired properties, but also good concrete releasability, withstands repeated use, and also has sufficient strength. The effect of is extremely remarkable.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a conventional synthetic resin concrete formwork.

[Explanation of symbols]

 1 Formwork 2 Recessed part 3 Convex part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Katsuno 1-17-20 Amanauma, Suginami-ku, Tokyo

Claims (3)

[Claims] 1. A polyolefin-based resin composition suitable for molding a concrete decorative formwork provided with a surface plate having recesses for expressing an appearance having a pattern such as a masonry on the surface of the cast concrete. Containing 5 to 55% by weight of a filler and having a linear expansion coefficient of less than 7 × 10 ⁻⁵ / ° C., a polyolefin resin composition for concrete decorative formwork. 2. The surface plate has a side wall on the outer periphery thereof, and further has a bottom plate at the lower end of the side wall, and these form a concave portion of the mold integrally formed with the hollow mold by blow molding. Polyolefin resin composition of. 3. The polyolefin resin composition according to claim 1, wherein the surface plate constitutes a concave portion of the thermoformed mold.