JPH10245259A - Production of reinforcing material for concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a reinforcing material excellent in bonding strength to a concrete by impregnating glass fibers with a thermosetting resin, arranging the impregnated glass fibers, winding the surfaces thereof with a multifilament yarn of a specific size at a specified density, fixing the shape so as to provide the cross section with a nearly circular form, covering the fixed impregnated glass fibers with alkali-durable fibers impregnated with a thermosetting resin, carrying out the pultrusion and thermosetting the resin. SOLUTION: A multifilament yarn comprising single filaments having 10-30μm single filament diameter is preferably used as glass fibers and wound around the surface of a glass fiber bundle at 1-100 pitches/10cm density. The yarn having 20-5,000 denier size uses glass fibers, polyester fibers, etc., and aramid fibers are preferred as sheath fibers. The volume content of core fibers is preferably 10-80%. An epoxy resin, etc., are used as a thermosetting resin and the ratio thereof accounts for preferably 20-70% of the reinforcing material. Thereby, the deterioration in strength of the glass fibers with an alkali and interfacial peeling thereof from the sheath fibers are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a reinforcing material for concrete, and more particularly, to a reinforcing material for concrete having a core-sheath structure using glass fiber as a core fiber, which has excellent alkali durability. This is a method for producing a reinforcing material for concrete without interfacial delamination.

[0002]

2. Description of the Related Art FRP rods have been developed and are often used for various purposes instead of reinforcing bars and high-strength steels conventionally used for the purpose of enhancing tensile strength. As these FRP rods, specifically, A using aramid fiber
FRP, CFRP using carbon fiber, GFRP using glass fiber, and the like have been proposed, and each has characteristics. For example, Japanese Patent Publication No. 63-59881 discloses a concrete reinforcing bar composed of a rod-shaped body having a core made of aromatic polyetheramide and a sheath made of a thermosetting resin. JP-A-49-62911 and JP-A-63-236848 disclose a reinforcing material for concrete using glass fiber as a core material and carbon fiber as an outer layer fiber. Tokiko Sho 63
The aramid 100% concrete reinforcing material disclosed in Japanese Unexamined Patent Publication No. 598991/1993 has a drawback that the amount of creep deformation at room temperature is large, and also Japanese Unexamined Utility Model Publication No. 49-62911 and Japanese Unexamined Patent Publication No. 63-236848. In the concrete reinforcing material disclosed in the above, the carbon fiber used for the outer layer fiber has a large modulus and a low elongation, so that it is brittle and difficult to process, in addition to having a weakness in electric spark, and furthermore, glass fiber and carbon fiber are used as a matrix. And the handling was difficult due to poor compatibility with the resin used.

Further, Japanese Patent Publication No. 7-18206 discloses that
In the continuous reinforcing fiber bundle (core fiber), a fiber wound around the core fiber, a secondary reinforcing fiber is arranged in an outer layer of the wound fiber, and a fiber wound around the secondary reinforcing fiber is arranged. Thus, there is disclosed a structural rod in which the disadvantage that the interfacial adhesion between the fiber and the thermosetting resin is low is improved. However, in Japanese Patent Publication No. 7-18206, the use of glass fiber as the core fiber is included in the range, but the alkaline durability of the glass fiber when the glass fiber is used as the core fiber for the secondary reinforcing fiber is described. There is no idea of improving the core fiber, and there is no idea of the secondary fiber covering the core fiber, and it does not solve the problem when glass fiber is used as the core fiber.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the problem of strength reduction due to alkali when glass fiber is used as a core fiber of a concrete reinforcing material. An object of the present invention is to solve the problem specific to glass fiber in which the interface between the core fiber and the sheath fiber peels off, and to propose a method for producing a concrete reinforcing material excellent in bonding strength with concrete.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a reinforcing material for concrete having a core-sheath structure comprising a glass fiber bundle as a core fiber and a sheath fiber covering the glass fiber bundle. After passing the fibers through a thermosetting resin bath to impregnate the thermosetting resin, the fibers are arranged in the yarn axis direction to form a fiber bundle, and the surface of the resin-impregnated glass fiber bundle is wound with a multi-filament yarn to form the fiber bundle. The shape of the glass fiber bundle is fixed so that the cross section perpendicular to the yarn axis direction is substantially circular, and then the surface of the glass fiber bundle is completely completed using alkali-durable fibers impregnated with a thermosetting resin as sheath fibers. The glass fiber bundle is arranged in the longitudinal direction of the glass fiber bundle so as to cover it, supplied, drawn, and then cured by heat treatment to cure the thermosetting resin. Hereinafter, the present invention will be described in detail.

FIG. 1 is a schematic process diagram for explaining the method of the present invention. It is necessary to impregnate the core fiber and the sheath fiber with a resin through a resin bath. Any of those impregnated with As shown in FIG. 1, the core fiber is subjected to resin drawing, then the multifilament yarn is wound, and the resin-impregnated sheath fiber is arranged and coated.

As the glass fiber used as the core fiber in the present invention, a commercially available glass fiber can be used, and the single fiber diameter is 10 to 3
An example using a multifilament yarn composed of a single fiber in the range of 0 μm is exemplified, and the total denier, the number of filaments, and the like are appropriately determined depending on the use of the concrete reinforcing material. The glass fibers are supplied to a resin bath and impregnated with a thermosetting resin. The glass fibers are supplied in a widened state so that the resin penetrates into each of the glass fibers. After passing through the resin bath, the glass fibers are removed as a fiber bundle by removing excess resin (resin squeezing).

Next, a multifilament yarn separately prepared is provided on the surface of the glass fiber bundle at a pitch of 1 to 100 pitch / 10c.
It is necessary to wind the fiber bundle at a density of m and fix the shape so that the cross-sectional shape of the fiber bundle becomes substantially circular. The number of turns is 1
If the pitch is less than / 10 cm, it is difficult to keep the cross section of the glass fiber bundle of the core fiber in a circular shape, and the number of turns is 100.
When the pitch exceeds 10 cm, not only the working efficiency is reduced but also the adaptability between the core fiber (glass fiber) and the sheath fiber is deteriorated, which is not preferable. A more preferable range of the winding density is 2 to 80 pitch / 10 cm.

The type of the multifilament yarn is not particularly limited, and may be glass fiber, carbon fiber, aramid fiber, or polyester fiber or polyamide fiber. Fibers of the same type as the sheath fibers described later have better handleability in the process. Further, it is necessary to use a multifilament yarn having a fineness (total denier) in the range of 20 to 5000 denier. If the denier of the multifilament yarn is less than 20 denier, it becomes difficult to wind the glass fiber bundle firmly to maintain the circular cross-sectional shape of the glass fiber, and if it exceeds 5000 denier, the winding of the glass fiber bundle becomes difficult. The surface irregularities due to the round fibers become large, and furthermore, since the multifilament yarn is not usually impregnated with a resin, an increase in the ratio of the multifilament yarn increases the compatibility between the core fiber (glass fiber) and the sheath fiber. Not preferred. A more preferred fineness range is 5
It is 0 to 3000 denier. Further, the monofilament constituting the multifilament yarn preferably has a small denier, and preferably has a denier in the range of 0.5 to 5 denier.

Next, a sheath fiber obtained by impregnating a resin into a glass fiber bundle having a multifilament yarn wound on the surface is supplied. It is important that the sheath fibers are arranged and supplied so that the surface of the glass fiber bundle is completely covered by the sheath fiber, and for this purpose, the sheath fiber is wound around a guide hole through which the glass fiber bundle passes. The fibers need to be supplied in a state of being evenly dispersed.

Since the sheath fibers are impregnated with resin, it is much more difficult to disperse them evenly around glass fibers than to disperse fibers in a dry state. It is preferable that the dispersion, arrangement and drawing are performed simultaneously and that the surface of the glass fiber is completely covered. In order to coat the sheath fiber on the surface of the glass fiber bundle, a method in which dispersion, arrangement and drawing are simultaneously performed through a guide as shown in FIG. 2 is preferably exemplified. That is, the glass fiber is passed through the guide hole 4, and three or more sheath fiber guide holes 5 are provided around the guide hole 4. FIG. 2 illustrates an embodiment of a guide used in the method of the present invention, and the present invention is not limited to this.

The sheath fibers used in the present invention must be alkali-durable fibers. What is alkali durable fiber?
Carbon fiber, vinylon fiber, aramid fiber, etc. are effectively exemplified, but the carbon fiber has a low elongation and the carbon fiber may be broken first by a load applied to concrete, and aramid fiber is used. Is optimally exemplified. Known aramid fibers can be used as the aramid fibers, but aromatic polyetheramide fibers, especially copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers, are used because of their excellent alkali durability. Are preferred. In addition, the usage ratio of the core fiber and the sheath fiber used in the present invention is such that the volume content of the core fiber (the ratio of the core fiber to the core-sheath fiber) is 10 to 80.
%, Preferably those in the range of 20 to 70% are suitably presented. If the volume content is less than 10%, the characteristics of glass fiber cannot be reflected on the concrete reinforcing material, resulting in insufficient tensile strength. If the volume content exceeds 80%, coating with the sheath fiber becomes difficult. It is not preferable because the object of the present invention cannot be achieved.

Further, as the thermosetting resin used in the present invention, epoxy resin, unsaturated polyester resin, vinyl ester resin (for example, epoxy acrylate resin), phenol resin, melamine resin and the like are effectively used. The proportion of the thermosetting resin in the reinforcing material is 20 to 70%
Is more preferable, and more preferably in the range of 30 to 60%. If the volume content of the thermosetting resin is less than 10%, the adhesiveness between the core fiber and the sheath fiber is insufficient, and 70%
If the ratio exceeds the above, the reinforcing effect of the fiber is not exhibited, and the object of the present invention cannot be achieved, which is not preferable.

In order to maintain and stabilize the coating of the sheath fiber, the sheath fiber is spirally wound around the sheath fiber using the same or different alkali-durable fiber as the sheath fiber, and has a strong structure. Are exemplified.

[0015]

In the concrete reinforcing material obtained by the method of the present invention, a multifilament yarn 2 is wound around a core fiber 1 as shown in FIG. The core fibers 1 are arranged in the yarn axis direction and have a structure covering the core fibers. Therefore, even when used as a concrete reinforcing material, the glass fiber does not come into direct contact with the concrete, thereby overcoming the problem of strength reduction of the glass fiber due to alkali.
FIG. 3 is a perspective view showing a concrete reinforcement obtained by the method of the present invention.

[0016] The glass fiber is poorly compatible with not only the sheath fiber but also the impregnated resin. As a countermeasure, the resin is impregnated into the sheath fiber, so that the lateral pressure of the sheath fiber becomes large. As a result, the sheath fiber is arranged and coated using the sheath fiber. -The cross-sectional shape of the glass fiber bundle is not easily formed into a circular shape when the drawing molding is performed. For example, when the guide shown in FIG. 2 is used, the cross-sectional shape of the glass fiber bundle is substantially triangular, which makes it difficult to obtain a complete covering with the sheath fiber and also as a concrete reinforcing material. When used, the stress distribution inside the reinforcing material becomes non-uniform and causes separation at the interface between the core component and the sheath component (interface separation). The interfacial peeling is an opportunity for the glass fiber bundle to come into contact with the alkali component of the concrete, and is a cause of deterioration in fatigue durability. In the method of the present invention, in order to solve this problem, the glass fiber bundle of the core fiber 1 has a cross section perpendicular to the yarn axis formed in a substantially circular shape, and not only is the sheath fiber coated uniformly, As a result, it has been found that the stress inside the reinforcing material is evenly dispersed when a load is applied, and interface separation hardly occurs, and as a result, fatigue durability is improved.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. In the examples, [parts] indicates parts by weight, and the physical properties used in the examples and comparative examples were measured by the following methods. (1) Tensile strength A tensile test of a sample (reinforcing material) was performed using a displacement control type autograph (10 tons) with a sample length of 40 cm and a tensile speed of 5
The measurement was performed at a rate of mm / min, and the number of n was measured as 10 to 20, and the tensile strength (initial) was determined from the average value. (2) Durable tensile strength A sample (reinforcing material) was subjected to 1.0 mol / L in an environment at a temperature of 40 ° C.
After immersion in a sodium hydroxide solution for 60 days, the tensile strength was measured by the method described above, and the result was shown by the retention rate of the initial tensile strength.

(3) Judgment of presence / absence of peeling of core fiber / sheath fiber A repetitive load (100 times) of 1 kgf / mm ² was applied to a substantially central portion of a sample (reinforcing material) having both ends gripped and fixed at a gripping distance of 20 cm. After loading, the sample is cut in the axial vertical section to determine the peeling state of the core / sheath fiber boundary.

[Examples 1 to 12] As the core fiber, a glass fiber multifilament yarn having a single fiber diameter of 13 µm (RSP110PA-535 manufactured by Nitto Glass Fiber) was used.
Seven fibers were combined to obtain a glass fiber bundle. The glass fiber bundle was led into a resin bath having the following structure, and after impregnation with the resin, was used as a core material of a reinforcing material by a drawing method.・ Thermosetting resin: 100 parts of acrylate resin Neopol 8250 (H) manufactured by Nippon Yupika ・ Curing accelerator: 3 parts ・ Lubricant: 1 part ・ Resin concentration: 38% in xylene solvent

Next, a multifilament yarn (400 denier / 266 denier) made of the following aramid fiber is wound on the surface of the glass fiber bundle core material.
Aramid fiber (1500 denier / 1000 filament) shown below impregnated with resin in the same resin bath 54
Using the book as a sheath fiber, to completely cover the surface of the glass fiber bundle, a double nozzle provided with nine sheath fiber supply guide holes around a guide hole for passing the glass fiber bundle, The glass fiber bundle and the sheath fiber were simultaneously supplied to arrange the glass fiber bundle in the longitudinal direction. Aramid fiber: copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber {Technola (registered trademark) manufactured by Teijin Limited>

Next, the fiber bundle having a core-sheath structure composed of the above three components was heat-treated at a temperature of 160 ° C. and a time of 7.5 minutes to cure the impregnated thermosetting resin to obtain a reinforcing material having a wire diameter of 6 mm. (Example 1). Similarly, in the reinforcing material, the volume content of the glass fiber as the core fiber, the aramid fiber as the sheath fiber and the thermosetting resin (volume content relative to the total reinforcing material), the fineness of the aramid fiber wound around the core fiber, The performance of the reinforcing material (Examples 2 to 12) obtained by changing the winding density as shown in Table 1 is also shown in Table 1.

[Comparative Examples 1 to 4] The same procedure as in Example 1 was repeated except that the winding density of the wound fiber was changed to 0.5 pitch / 10 cm (Comparative Example 1). Example 1 except that the winding density was 105 pitch / 10 cm
(Comparative Example 2), and further produced in the same manner as in Example 1 except that the fineness of the wound fiber was set to 15 denier and the winding density was set to 12 pitch / 10 cm. (Comparative Example 3), the fineness of the wound fiber was 5
100 denier, winding density 12 pitch / 10cm
Table 1 also shows the performance of the reinforcing material prepared in the same manner as in Example 1 (Comparative Example 4) except for the above.

[0023]

[Table 1]

In Table 1, as a judgment of the roundness of the cross section of the core fiber bundle, the mark ◎ indicates that the cross section is almost a perfect circle,
The mark indicates a substantially perfect circle, and the cross indicates a non-perfect circle.

Comparative Example 5 The procedure of Example 1 was repeated except that only glass fibers were used as the fiber bundle of the reinforcing material, and the fiber bundle was impregnated with the resin bath of Example 1 so that the volume content of the fiber bundle was 55%. Similarly, drawing and heat treatment were performed to obtain a glass fiber reinforcing material having a wire diameter of 6 mm. The same evaluation as in Example 1 was performed on this reinforcing material, and the results are as follows. Initial tensile strength 169Kgf / mm ² Durable tensile strength 50%

In Examples 1 to 12, the cross-section of the core fiber bundle was circular, and the covering with the sheath fiber was completely performed to obtain a reinforcing material having a durable tensile strength. In Comparative Examples 1 and 3, Comparative Example 2 lacks sufficient coverage and poor tensile strength durability.
In No. 4, the initial tensile strength was not sufficient, the adhesion between the core fiber glass fiber bundle and the sheath fiber was poor, and the durability of the tensile strength was not sufficient. In Comparative Example 5, although the initial tensile strength was high, the durability of the tensile strength was poor, and none of the objectives of the present invention could be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic process drawing for explaining the method of the present invention.

FIG. 2 is a diagram illustrating an embodiment of a guide used in the method of the present invention.

FIG. 3 is a perspective view showing a concrete reinforcement obtained by the method of the present invention.

[Explanation of symbols]

 1 is a core fiber 2 is a wound fiber 3 is a sheath fiber 4 is a guide hole for passing a glass fiber bundle 5 is a guide hole for a sheath fiber

Claims (3)

[Claims] 1. A method for producing a reinforcing material for concrete having a core-sheath structure comprising a glass fiber bundle as a core fiber and a sheath fiber covering the glass fiber bundle, wherein the glass fiber is passed through a thermosetting resin bath. After the thermosetting resin is impregnated, it is arranged in the yarn axis direction to form a fiber bundle, and a multi-filament yarn having a fineness of 20 to 5000 denier is wound on the surface of the resin-impregnated glass fiber bundle at a winding density of 1 to 100 pitches. The glass fiber bundle is wound in the range of / 10 cm, the shape is fixed so that the cross section perpendicular to the yarn axis direction of the glass fiber bundle is substantially circular, and then alkali-durable fiber impregnated with a thermosetting resin is used as a sheath fiber. After the glass fiber bundle is arranged in the longitudinal direction of the glass fiber bundle so as to completely cover the surface of the glass fiber bundle and supplied and subjected to drawing molding, the thermosetting resin is cured by heat treatment. Manufacturing method of concrete reinforcement. 2. The reinforcement for concrete according to claim 1, wherein three or more guide holes for the sheath fiber are provided around the guide hole through which the glass fiber bundle is passed, and the sheath fibers are supplied in a state of being substantially uniformly dispersed and then drawn. The method of manufacturing the material. 3. The method according to claim 1, wherein the alkali-durable fiber is an aramid fiber.