JPH11189448A - Fiber for reinforcing concrete and concrete formed product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fiber for reinforcing concrete, having large impact absorbing energy, improved in affinity and dispersibility with cement matrix and capable of improving flexural strength and compression strength of concrete foamed product, especially impact strength of concrete formed product and obtain a concrete formed product by using the fiber. SOLUTION: This fiber for reinforcing concrete comprises a polypropylene fiber having >=5 g/d single yarn strength and >=40% single yarn elongation and the fiber is obtained by attaching 0.1-10 wt.% at least one kind of surfactant having 8-22C alkyl group and selected from a group comprising a higher fatty acid metal salt, a higher alcohol sulfuric acid ester metal salt, a higher alkyl ether sulfuric acid ester metal salt, an alkylbenzenesulfonic acid metal salt, an alkylbenzenenaphthalenesulfonic acid metal salt, paraffin sulfonic acid metal salt, an alkylamine salt and an alkylammonium salt to polypropylene fiber. This concrete formed product is obtained by forming raw materials for concrete by using the fiber as a reinforcing material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fiber for reinforcing concrete having an excellent concrete reinforcing effect. More specifically, the present invention relates to a concrete reinforcing fiber suitably used for a concrete molded body mainly composed of building materials such as construction boards and tiles, and a concrete molded body formed using the concrete reinforcing fiber.

[0002]

2. Description of the Related Art Hardened cement is widely used in the fields of construction and civil engineering because of its low cost in addition to excellent properties such as compressive strength, durability and nonflammability. However,
Because it is a brittle material, it has extremely low flex resistance,
It easily breaks or cracks when bending stress is applied,
There are drawbacks such as low impact resistance. In recent years, in order to solve these problems, use of various inorganic fibers and organic synthetic fibers as fibers for reinforcing cement has been proposed. However, the properties of the fibers cannot be used effectively, or the fibers have both advantages and disadvantages, and the effects cannot be sufficiently exhibited.
The concrete reinforcement effect has not reached a satisfactory level. For example, olefin fibers have alkali resistance and heat resistance, and can be cured in an autoclave or steam, which is advantageous for concrete reinforcement. However, the surface of the olefin fiber is hydrophobic, has poor adhesion to a hydrophilic cement matrix, and has poor dispersibility in a cement slurry. As a prior art for solving this problem, there is known a technique for improving the affinity for cement by treating the surface of a fiber with a surfactant or the like (Japanese Patent Laid-Open No. 4-21).
556, JP-A-5-170497, PCT International Publication WO
90/06902). Although the fibers described in these prior art documents show a fairly good concrete reinforcing effect, there is a demand for a concrete molded body having further improved bending strength and impact strength. In recent years, in order to improve dispersibility and affinity, and to improve the reinforcing effect, the cross section of the fiber is deformed, projections or nodes are formed on the fiber surface, or the surface is coated with other components. There have been proposed improvement measures such as improving fiber strength, kneading other components, and specializing raw materials, but have not yet reached a satisfactory range.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the impact absorption energy, improve the affinity and dispersibility with a cement matrix, and improve the bending strength and compressive strength, particularly impact strength, of a concrete molded product. It is intended to provide a concrete reinforcing fiber that can be used.

[0004] The present inventors have conducted intensive studies to achieve the above-mentioned object, and as a result, have obtained not only the strength but also the elongation of the polypropylene fiber by making use of the knowledge on the physical properties and the concrete reinforcement of the polypropylene fiber. Maintaining a high level has the effect of improving not only the bending strength but also the impact strength of the concrete molding, and in combination with it, higher fatty acid metal salts, higher alcohol sulfate metal salts,
At least one selected from the group consisting of metal salts of higher alkyl ether sulfates, metal salts of alkyl benzene sulfonic acids, metal salts of alkyl benzene naphthalene sulfonic acids, metal salts of paraffin sulfonic acids, alkyl amine salts, and alkyl ammonium salts; When a surfactant having an alkyl group is attached to the surface of the polypropylene fiber, the impact absorption energy increases, and the affinity and dispersibility with the cement matrix are improved. Since the effect of dramatically improving the impact strength is seen, it is known that such polypropylene fiber is suitable as a fiber for reinforcing concrete, and a concrete molded article formed using the fiber has extremely excellent impact strength. Expression, and completed the present invention. This has led to the.

[0005]

The present invention has the following arrangement to solve the above-mentioned problems. (1) Concrete reinforcing fibers made of polypropylene fibers having a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more, wherein the fibers include higher fatty acid metal salts, higher alcohol sulfate metal salts, At least one selected from the group consisting of metal salts of higher alkyl ether sulfates, metal salts of alkylbenzene sulfonic acids, metal salts of alkyl benzene naphthalene sulfonic acids, metal salts of paraffin sulfonic acids, alkyl amine salts, and alkyl ammonium salts;
A concrete reinforcing fiber, wherein 0.1 to 10% by weight of a surfactant having an alkyl group of from 22 to 22 is attached to the weight of the polypropylene fiber. (2) The concrete reinforcing fiber according to the above (1), wherein the polypropylene fiber has a single yarn strength of 7 g / d or more and a single yarn elongation of 70% or more. (3) The concrete reinforcing fiber according to the above (1) or (2), wherein the metal salt is at least one kind of alkali metal salt selected from Na, Li, and K. (4) A concrete compact formed using the fiber for reinforcing concrete according to any one of the above (1) to (3).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polypropylene fiber used for the concrete reinforcing fiber of the present invention has a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more. The concrete reinforcing fiber of the present invention has a single yarn strength of 5 g / d or more, and a polypropylene fiber having a single yarn elongation of 40% or more, a higher fatty acid metal salt, a higher alcohol sulfate metal salt, or a higher alkyl ether sulfate. A metal salt, a metal salt of an alkyl benzene sulfonic acid, a metal salt of an alkyl benzene naphthalene sulfonic acid, a metal salt of a paraffin sulfonic acid, an alkylamine salt, or an alkyl ammonium salt, having an alkyl group having 8 to 22 carbon atoms. A concrete reinforcing fiber to which a surfactant is attached in an amount of 0.1 to 10% by weight based on the weight of the polypropylene fiber.

In a further preferred aspect of the present invention,
Single fiber strength of 7 g / d or more, and the above-mentioned surfactant is added to polypropylene fiber having a single yarn elongation of 70% or more, based on the weight of the polypropylene fiber, by 0.1 to 10% by weight of a concrete reinforcing fiber. is there. These metal salts of higher fatty acid salts, higher alcohol sulfates, higher alkyl ether sulfates, alkylbenzene sulfonates, alkylbenzene naphthalene sulfonates, and paraffin sulfonates are at least selected from Na, Li, and K. One alkali metal salt is used. Other salts are represented by primary amine salts, secondary amine salts and tertiary amine salts, and alkylammonium salts such as alkylamine salts and quaternary ammonium salts are used. Further, divalent metal salts such as Ca, Mg and Ba can also be used.

[0008] The polypropylene fiber used as the base material of the concrete reinforcing fiber of the present invention is obtained by mixing the raw material polypropylene with:
100% propylene units, 2% by weight or less of ethylene units in the polymer or olefin units having C4 or more such as butene-1, pentene-1,4-methylpentene-1, hexene-1, octene-1, etc. And a copolymer of polypropylene and another olefin. Further, a mixture of a crystal random copolymer or a block copolymer of propylene, ethylene and olefin may be used as the polypropylene resin.

The polypropylene resin according to the present invention includes:
Further, within the range not hindering the effects of the present invention, an antioxidant,
Light stabilizers, ultraviolet absorbers, neutralizers, nucleating agents, epoxy stabilizers, lubricants, antibacterial agents, flame retardants, antistatic agents, pigments, plasticizers, etc. Good.

Next, a method for producing a polypropylene fiber having a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more as a base material of the concrete reinforcing fiber of the present invention will be described. First, spinning is preferably performed at a spinning temperature in the range of 250 to 350 ° C, and more preferably in the range of 310 to 340 ° C, because it is possible to obtain an undrawn yarn with reduced fiber orientation.
When the spinning temperature is less than 250 ° C., the fibrous polypropylene melt extruded from the spinneret from the polypropylene melt melted by the extruder is rapidly cooled, and the fiber deformation at the solidification point is large, and the orientation is further advanced. However, it is not preferable because it is an undrawn yarn. In addition, when the spinning temperature exceeds 350 ° C, the decomposition of the polypropylene resin rapidly progresses, and it is difficult not only to obtain an undrawn yarn having good spinnability due to fiber firing, but also the molecular chains of the fiber are severely cut. Even if it is reduced in molecular weight and stretched, it does not become a high-strength polypropylene fiber.

When the extruded fibrous polypropylene melt is cooled, conventional methods such as air, water,
It can be cooled in a medium such as glycerin or the like to a temperature lower than the melting point, and can be drawn. However, in order to suppress the orientation of the undrawn yarn as much as possible, it is preferable to cool with air instead of quenching with liquid. Air temperature and air volume can be set arbitrarily,
In order to obtain an undrawn yarn with further suppressed orientation, it is preferable that the temperature is gradually cooled, that is, the air volume is weak and the temperature is not too low.
Such slow cooling is preferable because a higher-order crystal structure in which the lamellas are arranged at right angles to the fiber axis direction can be sufficiently formed.

[0012] The winding speed of the undrawn yarn is 200 to 1000 m / m so that the deformation at the solidification point of the fibrous polypropylene melt is small and the orientation does not progress.
It is preferably in. More preferably, it is preferable to take off at as low a speed as possible, so as not to be less than 200 m / min. On the other hand, if the take-up speed is 1000 m / min or more, the fibrous polypropylene melt is greatly deformed at the solidification point, becomes an oriented unstretched yarn, has poor stretchability, and cannot be stretched at a high magnification. On the other hand, if it is less than 200 m / min, high-temperature spinning cannot produce a uniform undrawn yarn which is slower than the natural falling speed of the polypropylene melt having a lowered melt viscosity.

The cross-sectional shape of the polypropylene fiber serving as the base material of the concrete reinforcing fiber can be circular or irregular. In the case of an irregular cross-section, any shape such as a flat shape, a square shape such as a triangular to octagonal shape, a T-shape, a multi-lobe shape, a hollow cross-sectional shape, etc., is not particularly limited.

Next, stretching will be described. The polypropylene undrawn yarn obtained by the above-described method is drawn to obtain a polypropylene fiber having high strength and elongation. A known method such as hot roll drawing, hot water drawing, and a heating plate is employed as a method for drawing the undrawn polypropylene yarn. The stretching operation is one-step stretching, 2
The stretching can be performed by any of step stretching and multi-stage stretching, but it is preferable to perform stretching operation of two or more steps rather than one-step stretching. Stretching is performed at a relatively low temperature of 50 to 90 ° C. When drawn at a temperature of 90 ° C. or more, the oriented crystallization of the undrawn yarn proceeds rapidly, and at a temperature lower than 50 ° C., the drawability is reduced and the draw ratio required for high strength cannot be obtained.

The stretching ratio at this time is preferably in the range of 4.2 to 6.0 times. More preferably, it is in the range of 5.0 to 5.8 times.
If it is less than 4.2 times, the single yarn strength is low, and if it exceeds 6.0 times, the single yarn elongation decreases. Next, when performing two-stage drawing, the film is drawn at a draw ratio of 40% or more, preferably 50% or more of the total draw ratio in one-step drawing, and then to a range where single yarn breakage and fluffing do not occur in the second step. It is preferable that the film is stretched and the total stretching ratio is within the above range. Even if the total stretching ratio is the same as the case where the single-stage stretching is performed at a stretching ratio of less than 40% of the total stretching ratio and the single-stage stretching is performed at 40% or more of the total stretching ratio, the high-strength polypropylene is used. Fiber cannot be obtained.
This is because orientation crystallization remarkably progresses in one-step stretching,
In two or more stages of stretching, unreasonable stretching takes place, and as a result, the strength does not increase. Here, the stretching ratio is represented by a ratio between a supply roll speed and a take-up roll speed.

Further, by subjecting the drawn product of the drawn polypropylene fiber to an annealing treatment at a temperature near the melting point by a constant length heat treatment, a relaxation heat treatment or the like, a polypropylene fiber having improved heat shrinkage can be obtained.

Through such spinning and drawing steps, a polypropylene fiber having physical properties of a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more can be obtained. In particular, spinning at a high temperature of 310 ° C or higher, low-temperature drawing or two-stage drawing is the most suitable for concrete reinforcement.
The above high elongation polypropylene fiber is obtained.

The surfactant may be attached to the polypropylene fiber in any of the spinning step and the drawing step. The adhesion method is a roller method, a dipping method, a spray method,
A pad dry method or the like can be used. Preferably, the attachment in the spinning step and the drawing step may provide uniform attachment.

The concrete reinforcing fiber of the present invention is a metal salt of a higher fatty acid having 8 to 22 carbon atoms, a metal salt of a higher alcohol sulfate, a metal salt of a higher alkyl ether sulfate, a metal salt of an alkylbenzenesulfonic acid, a metal salt of an alkylbenzenenaphthalenesulfonic acid. A suitable amount of at least one surfactant selected from the group consisting of a metal salt of paraffinsulfonic acid, an alkylamine salt and an alkylammonium salt, or the amount of the attached surfactant is 0.1 to 10% by weight based on the weight of the polypropylene fiber. is there. If it is less than 0.1% by weight, the reinforcing effect cannot be sufficiently obtained, and if it exceeds 10% by weight, the effect becomes saturated and the bending strength, impact strength and impact absorption energy reach equilibrium. Further, since the viscosity of the surface treatment agent is increased, productivity is deteriorated, and it is uneconomical, so that there is no need for practical use.

The concrete reinforcing fiber of the present invention has a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more.
The effect of reinforcing concrete, especially the effect of reinforcing impact strength, is improved.

The impact strength of concrete increases as the impact absorption energy increases. The impact absorption energy is energy from the time when the concrete molded body receives stress until the stress after rupture becomes zero.

When the single yarn elongation of the polypropylene fiber is 40% or more and the single yarn strength is 5 g / d or more, the impact absorption energy is more than the conventional value from the quadratic function of the elongation and the strength.
Impact strength increases. Further, if the single yarn elongation of the polypropylene fiber is 70% or more and the single yarn strength is 7 g / d or more, the impact absorption energy is dramatically improved, and the impact strength is improved.

That is, by attaching the above-mentioned surfactant to the surface of the polypropylene fiber, the affinity for concrete and the dispersibility are improved. The surfactant is a compound having both polarities of a hydrophilic group and a hydrophobic group. By adhering the surfactant to the surface of the polypropylene fiber, hydrophobic groups have an affinity between the polypropylene fiber and the surfactant and have a binding force, and a hydrophilic group is formed between the surfactant and the cement. The calcium ions in the cement are opposed to each other and the salt of the surfactant is replaced, and the calcium salt of the surfactant becomes an insoluble and sticky substance, and the cement particles adhere to the surface of the concrete reinforcing fiber. . That is, by interposing the surfactant between the polypropylene fiber and the cement, the adhesion between the cement and the concrete reinforcing fiber is strengthened and the affinity is improved, and the concrete reinforcing fiber is uniformly dispersed in the cement. And the dispersibility is improved.

The reinforcing effect can also be obtained by improving the elongation and strength of the polypropylene fiber or by adhering the surfactant, but a synergistic effect can be obtained by combining the two as in the present invention. In particular, polypropylene fibers having a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more,
Although it has excellent basic strength physical properties, the synergistic effect of attaching the surfactant in the previous period provides a good balance between the affinity of the polypropylene fiber and the surfactant, and further increases the adsorption power to the fiber surface. The effect of dramatically improving physical properties (particularly impact strength) is seen. This is because the prior art of the present invention is disclosed in Japanese Patent Laid-Open No. 5-170.
497 (especially Examples 8 and 10) have physical properties such as a breaking strength of 5 g / d or more and a breaking elongation of 40% or more. In contrast to 180 to 190 kgf / cm ² and impact strength of 3.4 to 3.7 kgf · cm / cm ² , the concrete molded body using the polypropylene fiber of the present invention has a flexural strength as shown in Examples described later. Is 21
0 kgf / cm ² or more, impact strength is 13 kgf · cm /
It is clear from the fact that it is dramatically improved to not less than cm ² .

[0025]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The bending strength was measured according to JIS-A1408. To measure the impact strength, a concrete molded body was 10 mm wide and 5 m thick
m, cut to 50 mm in length and performed according to JIS-B-7722 Charpy impact test. The measurement of the impact absorption energy was performed by analyzing the SS curve chart of the bending strength test and calculating from the area thereof.

Example 1 A melt flow rate (hereinafter referred to as MFR) 25 polypropylene was melt spun at a temperature of 250 ° C. and a take-up speed of 400 m / min, and then spun at 90 ° C.
And stretched 4.6 times, and the fiber diameter is about 17μm (about 2d / f)
With a fiber strength of 5.1 g / d and a fiber elongation of 42.1%, after stretching, apply 0.1% by weight of potassium oleate as a surface treatment agent to the fiber weight as a surface treatment agent with a touch roll, dry and cut it to 6 mm for concrete reinforcement Fiber.

Next, 1000 g of ordinary Portland cement,
1000 g of silica sand 7, 40 g of the concrete reinforcing fiber, 20 g of methylcellulose, and 360 g of water were mixed, kneaded using a kneader, and extruded to obtain a flat concrete molded body having a thickness of 5 mm and a width of 50 mm. This molded article was cured in water for 28 days, and then dried at 60 ° C. for 24 hours and at 95 ° C. for 8 hours to obtain a concrete molded article.

Example 2 A concrete molded body was obtained in the same manner as in Example 1 except that the amount of the surface treatment agent applied was changed to 9.8% by weight.

Example 3 A concrete molded product was obtained in the same manner as in Example 1 except that the surface treating agent of Example 1 was sodium lauryl ether sulfate and the amount of adhesion was 0.3% by weight.

Example 4 A concrete compact was obtained in the same manner as in Example 3 except that the amount of the surface treating agent of Example 3 was changed to 6.6% by weight.

Example 5 A concrete compact was obtained in the same manner as in Example 1 except that the surface treating agent of Example 1 was changed to sodium dodecylbenzenesulfonate and the amount of adhesion was 0.6% by weight.

Example 6 A concrete molded body was obtained in the same manner as in Example 5, except that the amount of the surface treating agent of Example 5 was changed to 3.2% by weight.

Example 7 A concrete molded body was obtained in the same manner as in Example 1 except that the amount of the surface treating agent of Example 1 was changed to 1.2% by weight.

Example 8 A concrete compact was obtained in the same manner as in Example 1 except that the surface treating agent of Example 1 was changed to potassium octylate and the amount of adhesion was 1.3% by weight.

Example 9 The surface treating agent of Example 1 was changed to potassium stearate,
A concrete molded body was obtained in the same manner as in Example 1 except that the amount of adhesion was 0.9% by weight.

Example 10 A concrete molding was obtained in the same manner as in Example 1 except that the surface treating agent of Example 1 was changed to potassium behenate and the amount of adhesion was 2.5% by weight.

Example 11 A concrete molding was obtained in the same manner as in Example 1 except that the surface treating agent of Example 1 was changed to an amine oleate salt and the amount of adhesion was 1.7% by weight.

Example 12 The surface treating agent of Example 1 was changed to sodium linoleate,
A concrete molded body was obtained in the same manner as in Example 1, except that the amount of adhesion was 4.4% by weight.

Comparative Example 1 A concrete molded body was obtained in the same manner as in Example 1 except that the amount of the surface treatment agent of Example 1 was changed to 0.05% by weight.

Comparative Example 2 Example 1 was repeated except that the surface treating agent of Example 1 was not adhered.
In the same manner as in the above, a concrete molded body was obtained.

Comparative Example 3 A concrete molded body was obtained in the same manner as in Example 3 except that the amount of the surface treating agent of Example 3 was changed to 0.03% by weight.

Comparative Example 4 A concrete molded body was obtained in the same manner as in Example 5 except that the amount of the surface treating agent applied was changed to 0.07% by weight.

The above "Examples 1 to 12" and "Comparative Example 1"
The results of evaluating the physical properties of the concrete molded product of “.
It is shown in Table 1.

[0044]

[Table 1]

As is clear from Table 1, Examples 1 to 12
Indicates that the concrete has an excellent effect of reinforcing the concrete.

In Comparative Example 2, the impact strength was particularly poor because there was no surface treatment agent. The effects of the fibers were not sufficiently brought out, and in Comparative Examples 1, 3, and 4, the adhesion amount of the surface treatment agent was less than 0.1% by weight, and the effect of reinforcing the fibers was not sufficiently exhibited.

Example 13 MFR40 polypropylene was prepared at a temperature of 330 ° C. and a take-up speed of 300 m.
After spinning at 60 ° C, the fiber is drawn in two steps at 60 ° C with a draw ratio of 3.1 times for the first step and 1.8 times for the second step. The fiber diameter is about 17μm (about 2d /
In f), the fiber strength was 7.3 g / d and the fiber elongation was 72.4%. After stretching, 1.1 wt% of potassium oleate was applied as a surface treatment agent with a touch roll and dried, and then cut into 6 mm to obtain concrete reinforcing fibers. .

Next, 1000 g of ordinary Portland cement,
1000 g of silica sand 7, 40 g of the concrete reinforcing fiber, 20 g of methylcellulose, and 360 g of water were mixed, kneaded using a kneader, and extruded to obtain a flat concrete molded body having a thickness of 5 mm and a width of 50 mm. This molded article was cured in water for 28 days, and then dried at 60 ° C. for 24 hours and at 95 ° C. for 8 hours to obtain a concrete molded article.

Example 14 A concrete molded body was obtained in the same manner as in Example 13 except that the surface treating agent of Example 13 was changed to potassium stearate and the amount of adhesion was 2.3% by weight.

Comparative Example 5 MFR25 polypropylene was taken at a temperature of 230 ° C. and a take-up speed of 500 m.
After spinning at 120 ° C / min, draw 4.3 times at 120 ° C.Fiber diameter is about 17μm (about 2d / f), fiber strength 4.3g / d, fiber elongation 25.
After stretching, 1.7% by weight of potassium oleate as a surface treatment agent was adhered as a surface treatment agent using a touch roll, dried, and then cut into 6 mm to obtain concrete reinforcing fibers.

Next, 1000 g of ordinary Portland cement,
1000 g of silica sand 7, 40 g of the concrete reinforcing fiber, 20 g of methylcellulose, and 360 g of water were mixed, kneaded using a kneader, and extruded to obtain a flat concrete molded body having a thickness of 5 mm and a width of 50 mm. This molded article was cured in water for 28 days, and then dried at 60 ° C. for 24 hours and at 95 ° C. for 8 hours to obtain a concrete molded article.

Comparative Example 6 Comparative Example 5 was repeated except that the surface treating agent of Comparative Example 5 was not adhered.
In the same manner as in the above, a concrete molded body was obtained.

Comparative Example 7 MFR32 polypropylene was prepared at a temperature of 300 ° C. and a take-up speed of 400 m.
After melt-spinning at 120 ° C / min, the fiber is stretched 5.1 times at 120 ° C, the fiber diameter is about 17μm (about 2d / f), fiber strength is 6.9g / d, fiber elongation is 21.
After stretching, 1.6% by weight of potassium oleate was applied as a surface treatment agent using a touch roll after drying, dried, and cut into 6 mm to obtain concrete reinforcing fibers.

Next, 1000 g of ordinary Portland cement,
1000 g of silica sand 7, 40 g of the concrete reinforcing fiber, 20 g of methylcellulose, and 360 g of water were mixed, kneaded using a kneader, and extruded to obtain a flat concrete molded body having a thickness of 5 mm and a width of 50 mm. This molded article was cured in water for 28 days, and then dried at 60 ° C. for 24 hours and at 95 ° C. for 8 hours to obtain a concrete molded article.

Comparative Example 8 Comparative Example 8 was carried out except that the surface treating agent of Comparative Example 8 was not adhered.
In the same manner as in the above, a concrete molded body was obtained.

Comparative Example 9 MFR28 polypropylene was heated at a temperature of 250 ° C. and a take-up speed of 350 m.
After spinning at 60 ° C / min, draw 3.8 times at 60 ° C, fiber diameter is about 17μm (about 2d / f), fiber strength is 3.4g / d, fiber elongation is 72.
After stretching, 1.3% by weight of a potassium oleate as a surface treatment agent was adhered thereto by a touch roll after stretching, dried, and cut into 6 mm to obtain a fiber for concrete reinforcement.

Next, 1000 g of ordinary Portland cement,
1000 g of silica sand 7, 40 g of the concrete reinforcing fiber, 20 g of methylcellulose, and 360 g of water were mixed, kneaded using a kneader, and extruded to obtain a flat concrete molded body having a thickness of 5 mm and a width of 50 mm. This molded article was cured in water for 28 days, and then dried at 60 ° C. for 24 hours and at 95 ° C. for 8 hours to obtain a concrete molded article.

Comparative Example 10 Comparative Example 9 was repeated except that the surface treating agent of Comparative Example 9 was not adhered.
In the same manner as in the above, a concrete molded body was obtained.

Comparative Example 11 A concrete molded body was obtained in the same manner as in Example 13 except that the surface treating agent of Example 13 was not adhered.

Table 2 shows the results of evaluating the physical properties of the concrete compacts of "Examples 13 and 14" and "Comparative Examples 5 to 11".

[0061]

[Table 2]

As is clear from Table 2, Examples 13 and 14
It can be seen that the concrete reinforcing fiber of Example 1 has an excellent concrete reinforcing effect. The reinforcing effects of Examples 13 and 14 show a dramatic improvement over the reinforcing effects of Examples 1 to 12. Although this is a satisfactory value in Examples 1 to 12, the impact absorption energy is significantly increased by further increasing the fiber strength to 7 g / d and the elongation to 70%, so that the reinforcing effect of the concrete molding is remarkably increased. Rise.

In Comparative Examples 5 to 11, since the physical properties of the fibers were not at a satisfactory level, the reinforcing effect was not so much observed. Further, in Comparative Examples 6, 8, and 10, there was no surface treatment agent, and the effect of the fiber could not be sufficiently obtained.
The reinforcement effect is not obtained as compared with Comparative Examples 5, 7, and 9. In addition, when comparing Example 13 with Comparative Example 11, even if the fiber properties are at a satisfactory level, the reinforcing effect cannot be sufficiently exhibited because there is no surface treatment agent. That is, the fiber physical properties are fiber strength 5 g / d, fiber elongation 40% or more, more preferably fiber strength 7
g / d, the fiber elongation is 70% or more, and the effect of the present invention can be obtained by performing a surface treatment with the surface treatment agent.

[0064]

The fiber for reinforcing concrete of the present invention has an excellent concrete reinforcing effect. Since the strength and elongation of the fiber are high and the binding property with the special surface treating agent is strong, the reinforcing effect can be sufficiently exhibited in the concrete molded body, and the strength of the concrete molded body can be improved. In particular, it was possible to obtain a fiber for reinforcing cement which improved the bending strength, particularly the impact strength, of the concrete molded article due to its high elongation.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 13/256 D06M 13/256 13/322 13/322 13/325 13/325 (72) Inventor Tokuhiro Nakai Entering Moriyama City, Shiga Prefecture 251-cho, Town (72) Inventor Hiroaki Nishio 889, Koshinohara, Yasu-cho, Yasu-gun, Shiga Prefecture 1 Grand Court Yasu 505 (72) Inventor Kunio Kimura 34, 218 218 Kayakatacho, Tosu-shi, Saga Prefecture (72) Inventor Nori Kamio 23, 1011 Kokura, Oyama, Kiyama-cho, Miyoki Group, Saga Prefecture

Claims (4)

[Claims] 1. A concrete reinforcing fiber comprising a polypropylene fiber having a single yarn strength of 5 g / d or more and a single yarn elongation of 40% or more, wherein the fiber includes a higher fatty acid metal salt and a higher alcohol sulfate ester metal. Salts, metal salts of higher alkyl ether sulfates, metal salts of alkyl benzene sulfonic acids, metal salts of alkyl benzene naphthalene sulfonic acids, metal salts of paraffin sulfonic acids, alkyl amine salts, alkyl ammonium salts, and having 8 carbon atoms. A concrete reinforcing fiber, wherein 0.1 to 10% by weight of a surfactant having an alkyl group of from 22 to 22 is attached to the weight of the polypropylene fiber. 2. The concrete reinforcing fiber according to claim 1, wherein the polypropylene fiber has a single yarn strength of 7 g / d or more and a single yarn elongation of 70% or more. 3. The method according to claim 1, wherein the metal salt is at least one alkali metal salt selected from Na, Li, and K.
The fiber for reinforcing concrete according to item 1. 4. A concrete molded article formed using the fiber for reinforcing concrete according to claim 1.