JP2957587B2 - Reinforcement made of high-strength polyvinyl alcohol-based fiber and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to reinforcing bars buried in concrete and plastics, tensile materials for prestressed concrete, reinforcing materials for transmission lines and optical fiber communication cables, and the like. The present invention relates to reinforcing bars and tensile members used.

<Related Art and Problems to be Solved by the Invention> Conventionally, various reinforcing bars specified in JIS G 3112 and 3117 have been used for reinforcing concrete. As tensile material for prestressed concrete, JIS is used as PC steel.
G 2536, 3109, 3538, and various other prescribed types are used. Since these are materials containing iron as a main component, they generate rust. It is said that this rust is generated by carbonation of concrete and the intrusion of water due to cracks and oxygen in the air. To prevent this, it is necessary to make the thickness more than a certain level (called fog thickness). Have been. However, this is a major drawback to the generation of rust, which is said to be the cause of the formation of internal batteries due to salts and ions in the concrete and the electrical action in the environment, which causes corrosion of the reinforcing steel. In particular, it is powerless against rusting of marine structures, coastal structures and buildings. On the other hand, the fact that iron has the electrical conductivity and the magnetism, which are the characteristics of iron, are major drawbacks. One of them is unsuitable for structural materials that use magnetic fields, such as causing leakage or short circuit of communication signals, generating electromotive force by external magnetic field, causing rust, and greatly affecting external magnetic field. It is. In addition, since iron is heavy, the workability is deteriorated. In addition to the necessity of increasing the fog thickness for rust prevention, the structure itself has a disadvantage that the weight of the structure itself must be large. Techniques for solving these disadvantages of iron include, for example, JP-A-60-215559 and JP-A-62-1383.
In addition to the technology described in Japanese Patent No. 47, the 6th Annual Conference on Concrete Engineering (1984, 369-372) and the 8th Annual Conference on Concrete Engineering (1986, 657-660 and 661) To 664). These techniques use glass fiber, aramid fiber, and carbon fiber as a tensile material, and acrylic epoxy resin and vinyl ester resin as an adhesive. In addition, reinforcement plastics (1988, 36, pp. 9-17) discuss concrete lattice materials; civil engineering (13, 12 pp. 88) discusses various types of concrete reinforcement rods. JP-A-62-260947 and JP-A-62-28882
JP-A-48-63 and JP-A-63-139735 have a fiber-reinforced reinforcing bar, and JP-A-62-288248 discloses a braided material that substitutes for a PC steel wire. The necessary conditions for reinforcing bars and tensile materials are high-strength, high-modulus synthetic fibers that are alkali-resistant, non-magnetic, non-conductive, and creep against loads. It is necessary to reduce the phenomenon. In addition, when used as reinforcing bars and tensile materials, the fibers must be aligned and molded to a certain degree or more in order to increase the strength utilization rate of the fibers. When used for cement, the resin must have alkali resistance. Furthermore, it is economical to be used as an industrial material and has the potential to be supplied in large quantities.

In view of these points, glass fibers are not suitable for durable use even though they are alkali-resistant glass fibers. Further, carbon fibers are not preferable in terms of electrical conductivity and adhesiveness to resin. Furthermore, in the form difference, the braided shape has a twill,
In addition to the fact that the fiber strength is not sufficiently exhibited from the viewpoint of fiber alignment, a creep phenomenon occurs with the lapse of time, and the reinforcing bars and the tensile material have the disadvantage that they cannot exhibit their original abilities. The present inventors have intensively studied to solve these problems and arrived at the present invention.

<Means for Solving the Problems> The present invention has a tensile strength of 15 g / dr or more and a Young's modulus of 300 g / d.
At least 60% by volume of the polyvinyl alcohol-based synthetic fiber is made of a thermosetting resin, and at least 50% of the polyvinyl alcohol-based synthetic fiber is aligned. Reinforcement, and
As a preferred production method, the tensile strength is 15 g / dr or more,
A thermosetting resin is impregnated with a polyvinyl alcohol-based synthetic fiber having a Young's modulus of 300 g / dr or more and a fineness of a single fiber of 0.5 to 20 deniers, and the fiber content is given while giving a tension so that a draw ratio becomes 0.05 to 2%. Draws at 60% by volume or more and simultaneously heat-molds to produce a rod with 50% or more of the single fiber aligned in the drawing direction, and then wraps a thread on the surface of the rod to join the reinforcement. Method.

Polyvinyl alcohol (hereinafter referred to as PVA) used in the present invention
Abbreviation) synthetic fiber has a degree of polymerization of 1,000 to 20,000 and a degree of saponification of 9
A PVA of 8 mol% or more is used. The fiber must have a tensile strength of 15 g / dr or more and a Young's modulus of 300 g / dr or more. Preferably tensile strength 17-30 g / dr, Young's modulus 45
It is 0 to 1000 g / dr. Tensile strength and Young's modulus 15g / dr
If it is less than 300 g / dr, the performance as a fiber reinforcing material cannot be sufficiently exhibited.

The present inventors have surprisingly used a PVA-based synthetic fiber having a high strength and a high Young's modulus to invent a tensile material that surprisingly covers the defects of a reinforcing bar and further imparts durability and creep resistance. Was.

The condition that the fineness is 0.5 to 20 deniers is a suitable condition for producing a fiber having a high strength and a high Young's modulus, and is necessary for increasing the surface area of the fiber to enhance the adhesive force with the resin. From the viewpoint of surface area, fine denier of less than 0.5 denier is more preferable, however, it is not preferable because the fiber alignment during pultruding and the volume% of the fiber after resin impregnation are reduced. On the other hand, high strength beyond 20 denier,
A fiber having a high Young's modulus cannot be obtained, and a sufficient reinforcing bar or a tensile material cannot be obtained due to a decrease in the adhesive area with the resin.

Although various thermosetting resins can be selected, the reinforcing bars used for cement concrete and the tensile material for prestressed concrete are used in cement alkali. Cannot be used at the bonding interface. In addition, it is necessary to use a heat-resistant resin for the reinforcing material of transmission lines and optical fiber communication cables, and in these respects, it is possible to sufficiently exert the power as a bundle when the fibers are bundled. A thermosetting resin is used, and among them, for a reinforcing material or a tensile material for cement concrete, glycols, polyols, polyglycidyl ether compounds obtained by reacting epichlorohydrin, or alcohols or phenols are used. Monoglycidyl ether compound,
Typically, an epoxy resin obtained by a condensation reaction from bisphenol A and epichlorohydrin is preferable, and the epoxy resin is particularly excellent in adhesiveness, probably because of the action by opening the hydroxyl group and the epoxy group of PVA. There is no deterioration with the cement alkaline solution, and no decrease in the adhesive strength with the PVA fiber is observed.

Melamine-formalin-based, phenol-based, and urea-based thermosetting resins can also be used. Further, in order to reinforce a cable or the like, an unsaturated polyester resin can be used in addition to the above-mentioned resins.

The fiber content volume in the resin must be 60% or more. The reason that the strength of the fiber as a reinforcing material can be exhibited is that the resin with less matrix component is less than the composite rule using continuous fiber. It is clear that the tensile strength and Young's modulus of the composite material increase. In the present invention, if the volume occupied by the fibers in the composite material is not 60% or more, the mechanical properties such as the fiber strength and Young's modulus are reduced, and it is meaningless. In addition, in the case of the pultrusion molding, in order to suppress the infiltration of air when the fiber passes through the inside of the pulverization nozzle, and in order to mold the lubrication, it is preferable to use a large amount of resin, but in order to satisfy the mechanical properties of the composite. Should be less than 40% resin.

The form of the fiber aggregate in the composite has important significance when used as reinforcement or tensile material. That is, the orientation of the fibers in the pultruded rod is 50% or more, preferably 70% or more.
% Or more, if the fibers are not aligned in the fiber direction, no matter how perfect the bonding is, even if the tensile stress applied to the aggregate of the fibers is shared among the individual fibers, the stress received by each fiber will be different. Fiber aggregate does not show 100% power, 30 ~ 5
It is considered that only 0% of the force can be exerted.

As a conventional technology, after twisting and bundling fibers,
A method for producing a reinforcing fiber bundle by impregnating an adhesive resin is known. In the fiber bundle obtained by this method,
Generally, single fibers do not extend straight in the fiber bundle direction due to twisting. Therefore, with such a fiber bundle, it is not possible to sufficiently exhibit the strength of the fiber, and particularly to suppress creep. In the present invention, it is important that the fibers exist in a straight state without substantially twisting in the drawing direction of the fiber assembly. In other words, it is important that at least 50% of the fibers are substantially perfectly aligned.

An arbitrary part of the drawn molded body is taken in a length of 1 cm and cut in parallel to the fiber axis direction, and the number of aligned fibers in the fiber molding axis direction in the cutting plane is counted with a microscope to determine the ratio of the aligned fibers. it can. To control the fiber alignment and to perform crimping while applying tension at the forming nozzle so that the draw ratio is 0.05 to 2% after resin impregnation to minimize creep after loading.
It became possible to mold while 50% or more of the fibers were aligned.

The surface of the molded body is a tensile material for prestressed concrete,
Reinforcing materials such as power transmission cables and optical fiber cables have diameters
It can be wound up to 1 mm to 10 mm, preferably 3 to 9 mm without any surface irregularities. On the other hand, it is preferable that the diameter is 6 to 60 mm as a substitute for the reinforcing steel for concrete. Further, in the present invention, in order to mechanically impart adhesiveness to concrete or the like, it is necessary to produce protrusions on the rod-like surface similarly to the deformed reinforcing bar. As a method of providing projections, the present inventors have found a method of winding a thread on the surface of a rod. The filamentous material has a total fineness of 1 at the time of molding a molded rod.
It is preferable that the denier has a thickness of about 5% and that twisting is applied 50 to 200 times per meter in order to enhance deformability. For example, a twisted yarn made of PVA-based synthetic fiber, aramid-based synthetic fiber, polyarylate-based synthetic fiber, etc., impregnated with the resin used at the time of the draw-molding, and the rod-shaped material after the draw-molding is formed at an angle of 40 to 50 ° with respect to the axial direction It has been found that a deformed rod can be obtained by a method of winding and heat-treating with two cords so as to be obliquely attached and joining them. The winding pitch is called the diagonal steeping interval, and the value obtained by dividing the average interval of the stitching by the diameter of the rod state is 0.6 to
0.8 is preferred, and a pitch of about 0.7 is most preferred.

Next, the production method of the present invention will be described. First, the degree of polymerization
Single fiber denier 0.5 to 20 denier, tensile strength 15 g / dr or more, preferably 17 to 30 g / dr, Young's modulus 350 g / dr or more by wet spinning using PVA of 1000 to 200,000 and saponification degree of 98 mol% or more And preferably 450 to 1000 g / dr of PVA synthetic fiber. The PVA fiber is wound in a cheese form as a yarn of 500 to 5000 denier, set on a bobbin creel equipped with a constant feeding tension device, the yarn is drawn out, guided to a resin impregnation tank, dipped, and guided to a drawing molding nozzle. Pulled out while adhering and defoaming resin 130-2
Pass through a heating furnace at 50 ° C. The resin is cured and molded by heating. The thread alignment between the resin impregnation tank and the hot drawing must be almost perfect as described above, and 0.05 to 2% of the fiber must be used for the drawing to be 50% or more. It is necessary to mold while applying tension to give stretching. This also has the effect of reducing fiber creep. The application of the deformability may be performed in the same step as the resin dip code after the heat curing, or may be performed as a separate step.

<Function> As a reinforcing material according to the present invention, it can be used as a reinforcing steel substitute for mortar and concrete for all members in terms of mechanical strength, durability and economy. In particular, it can be used as a non-magnetic, non-conductive special reinforcement for linear motor cars. On the other hand, it can be used as a tensile material and reinforcing material for PC steel wire, power transmission cable, and optical fiber communication cable, as well as a wire material with low creep (relaxation) as well as tensile strength. The rod-shaped material can also be used for fiber-reinforced bolts, wood screws, and the like that do not rust by being threaded. Hereinafter, an embodiment will be described.

Example 1 Wet spinning from a PVA solution having a degree of polymerization of 4500 and a degree of saponification of 99.9 mol% was carried out to give 1800 denier 1000 having a single fiber fineness of 1.8 denier, a tensile strength of 18.5 g / dr, an elongation of 3.5% and a Young's modulus of 460 g / dr. Filament PVA fiber was obtained. Attach the fiber 140 cheese to a creel equipped with a tension control device and reduce the total denier to 25.
The density was set to 2000 denier, and it was carefully introduced into the rotating date roll so that the tow was not disturbed in the impregnation tank of the epoxy resin (Epicor 828 manufactured by Yuka Shell Epoxy). The resin adhesion rate is reduced to 30% by volume, and the fiber volume is 70%.
%. A pultruding nozzle having a circular diameter of 6 mm was used. The curing temperature of the resin was 180 ° C., and molding was performed at 3 m / min. Further, the drawing roll speed after heat curing was 0.7% higher than that of the date roll. Cut out the molded rod 1cm,
When the alignment of the fibers was observed with a microscope, it was observed that an average of 85% or more was aligned in the fiber axis direction.

As Comparative Example 1, the polyvinyl alcohol fiber had a fineness of 1.
An 8-denier 1800 denier 1000 filament, a tensile strength of 9.6 g / dr, an elongation of 6.8% and a Young's modulus of 280 g / dr were used, and this was used as 140 cheese. As Comparative Example 2, aramid fiber (Dupon '
Kevlar manufactured by T Co., Ltd., 29,1500dr / 1000f), a denier of 1.5 denier, a tensile strength of 21g / dr, an elongation of 3.9%, and a Young's modulus of 470g / dr were molded using 168 cheese in the same manner as in Example 1. . In order to impart deformability, the molded articles of Example 1 and Comparative Example 1 were made of two 1800 denier yarns and used for 1 m.
The same epoxy resin as that of the pultruded product was impregnated with 120 twists per time, and was impregnated clockwise and counterclockwise at pitches of 8.5 mm with respect to the axial direction. Example 2 was carried out in the same manner as Example 1 and Comparative Example 1 using two 1500 denier yarns.

Table 1 shows the physical properties of the rods obtained in Example 1 and Comparative Examples 1 and 2.
Shown in

The tensile strength was measured using an Instron TT-CM with a test length of 30.
The strain gauge was attached to the sample in cm.

The creep performance of the fibers used in Example 1 and Comparative Examples 1 and 2 was examined in accordance with JIS-L-1017. The initial load was 1/30 of the breaking strength, the load was 1 / 3.5 of the breaking strength, and the sample was left in a test length of 1 m, room temperature of 25 ° C, and relative humidity of 60%. The creep (relaxation rate) performance is shown in Table-2.

Example 1 is very small as compared with Comparative Example 1 having a large creep rate, and has a great feature that creep stops instantaneously. Although Comparative Example 2 is a fiber having high strength and high Young's modulus, stress relaxation occurs over a long period of time, which is not preferable as a tensile material or a reinforcing material.

Example 2, Comparative Examples 3, 4, 5 Comparison of the deformed muscle prepared in Example 1 (Examples 2 and 3) with the deformed muscle prepared in Comparative Example 2 for comparison as a reinforcing bar in cement matrix. A commercially available D6 atypical muscle was used as Examples 3 and 4 and Comparative Examples 5 and 6, and the reinforcing effect was examined at a bar arrangement rate of 0.28%. In addition, planes with no reinforcement were used as Comparative Examples 7 and 8.

The cement mortar used in Example 2 and Comparative Examples 3, 5, and 7 was 100 parts by weight of fast-strength cement (Asano fast-strength cement) (hereinafter, all parts by weight), 300 parts of silica sand (Inkstone silica sand No. 6.5), and gravel (Okayama). 150 parts of Asahikawa (5 mm particle size or less) were weighed, and dry mixing was carried out for 1 minute with an omni mixer. Then, 52 parts of water and 2.5 parts of a water reducing agent (Kao Mighty 150) were added and mixed for 2 minutes to obtain a mortar.

The compounding of the lightweight cement mortar used in Example 3 and Comparative Examples 4, 6, and 8 was 100% of early-strength cement (Asano early-strength cement).
Parts, 10 parts of fine powder parla mate (Ube 1 type) and expansion (Denka CSA # 20, manufactured by Denki Kagaku Kogyo Co., Ltd.)
After mixing for 3 minutes, 3 parts of a foaming agent (formix C2, manufactured by Hamano Industry Co., Ltd.) and 1 part of a water reducing agent were added and mixed for 2 minutes with an omni mixer to obtain a mortar.

For molding, use a standard formwork of 10cm x 10cm x 40cm, and apply 2 pieces in the length direction (bar arrangement ratio 0.28%) so that the cover thickness is 1cm.
The distance was fixed at cm. 10cm × 10cm × 40 for those not arranging
A cm-shaped frame was used.

The cement mortar of Example 2, Comparative Examples 3, 5, and 7, and the lightweight cement mortar of Example 3, Comparative Examples 4, 6, and 8 were cast and molded.

Curing was carried out in Example 2 and Comparative Examples 3, 5 and 7 at room temperature for 24 hours, followed by curing for 4 weeks. In addition, they were left in seawater to observe long-term stability, and changes after one year were observed.

Example 3 and Comparative Examples 4, 6, and 8 were left at room temperature for 24 hours and then demolded, and then left to stand in the air for 4 weeks.

The bending strength was measured by a universal tester manufactured by Shimadzu. With a span length of 30 cm, the maximum breaking load and
The deflection was measured. The bending strength is calculated from the ratio between the section modulus and the second moment. (Where P is the load, L is the span length, b is the width of the member, and t is the thickness of the member). It is shown in Table-3.

Regarding the reinforcement of the cement mortar, Example 2 is five times as strong as Comparative Example 7, is superior to Comparative Examples 3 and 5, and has excellent durability.

Example 2 is superior to other comparative examples also in reinforcing lightweight cement mortar.

Continuation of the front page (56) References JP-A-61-40113 (JP, A) JP-A-56-128309 (JP, A) JP-A-63-4160 (JP, A) JP-A-1-174533 (JP) , A) JP-A-2-127583 (JP, A) JP-A 62-149910 (JP, U) JP-A 61-202443 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB Name) C04B 16/06 D01F 6/14

Claims (2)

(57) [Claims] 1. A tensile strength of 15 g / dr or more and a Young's modulus of 300 g / d.
At least 60% by volume of the polyvinyl alcohol-based synthetic fiber is made of a thermosetting resin, and at least 50% of the polyvinyl alcohol-based synthetic fiber is aligned. Reinforcement. 2. A tensile strength of 15 g / dr or more and a Young's modulus of 300 g.
/ dr or more, impregnating a thermosetting resin with a polyvinyl alcohol-based synthetic fiber having a single fiber fineness of 0.5 to 20 denier and applying a tension so that the draw ratio becomes 0.05 to 2%, and the fiber content is 60 volume %. A method for producing a reinforcing material in which a rod-like body in which 50% or more of a single fiber is aligned in the drawing direction is produced by simultaneously drawing and heating at a ratio of at least 50%, and a thread is wound around the rod-like body and joined.