JP2744258B2 - Reinforcing material comprising wholly aromatic polyester 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 G3112 and 3117 have been used for reinforcing concrete. As tensile material for prestressed concrete, JISG is used as PC steel.
Various types specified in 2536, 3109, 3538 and others 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, water intrusion due to cracking, and oxygen in the air. To prevent this, it is required to make the thickness more than a certain thickness (referred to as fog thickness). Have been. However, it is a major drawback against rust, which is said to cause rust, which is said to be the cause of rust, which is caused by the formation of internal batteries due to salts and ions in concrete and the electrical action in the environment. . 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 magnetism, which are characteristics of iron, are also major drawbacks. One of them is that it is not suitable for structural materials that use magnetic fields, such as causing leakage or short-circuit of communication signals, generating electromotive force due to external magnetic fields, causing rust, and greatly affecting external magnetic fields. It is. In addition, since iron is heavy, it deteriorates workability. In addition to the necessity of taking a fog thickness for rust prevention, there is a drawback that the structure itself must be heavy.

As a new technique for these iron-based rebars and PC steels, studies have been made to improve the defects of iron using synthetic fibers. For example, the 6th Annual Conference on Concrete Engineering (1984 pp. 369-372) and the 8th Annual Conference on Concrete Engineering (1986 657-660, 661-664) contain glass as a tensile material. Research presentations using acrylic epoxy resin and vinyl ester resin as fibers, aramid fibers, carbon fibers, and their adhesives. Reinforced plastic (1988 36-6 pp. 9-17) has concrete reinforcement grid materials, In civil engineering technology (13:12, p.88), various rods for concrete reinforcement have been studied. Further, JP-A-62-260947, JP-A-62-288248, and 63
Japanese Patent Application Laid-Open No. 62-139735 discloses a fiber reinforced reinforcing bar.
At −288248, a braided material as an alternative to a PC steel wire is shown. The necessary requirements for reinforcing bars and tensile members are synthetic fibers with high strength and high Young's modulus, and the synthetic fibers must be alkali-resistant, non-magnetic, not conductive,
It is necessary that the creep phenomenon be small with respect to the load. In addition, when used as reinforcing bars and tensile materials, in order to increase the strength utilization rate of fibers, the fibers must be aligned and molded more than a certain amount, and fibers that are sufficient to transmit the stress applied to the fiber molded body to the fibers The resin must have the adhesive strength of the resin and must have alkali resistance when used for cement. 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 fineness of 1 to 3000 denier and a tensile strength of 15
g / dr or more, a wholly aromatic polyester synthetic fiber having a Young's modulus of 300 g / dr or more is composed of a thermosetting resin in an amount of 60% by volume or more, and 50% or more of the wholly aromatic polyester synthetic fiber is a fiber aggregate. It is a rod-shaped reinforcing material that is aligned in the pulling direction and is present in a straight state without being substantially twisted, and as a preferable manufacturing method, has a tensile strength of 15 g / dr or more, Young The rate is 300 g / dr or more, the fineness of a single fiber is impregnated with a thermosetting resin with a wholly aromatic polyester synthetic fiber having a denier of 1 to 3000 denier, and the stretching rate is 0.05
The fiber content is increased while giving a tension of ~ 2%.
Characterized in that it is heat-molded so as to have a volume of 60% by volume or more, wherein 50% or more of the wholly aromatic polyester-based synthetic fibers are aligned in the drawing direction of the fiber aggregate and straight without substantially twisting. The method uses a method of manufacturing a rod-shaped reinforcing material that exists in a proper state. The present inventors have invented a tensile material surprisingly covering defects of the reinforcing bar and further imparting durability and creep resistance by using a high-strength, high Young's modulus wholly aromatic polyester-based synthetic fiber. Reached.

A wholly aromatic polyester as used herein is an aromatic polyester which can be melt-processed by condensation of one or more aromatic hydroxy acids, optionally with aromatic diols and / or aromatic diacids. A wholly aromatic polyester, referred to as wholly aromatic in the sense that at least one aromatic ring of each component contributes to the polymer backbone,
It refers to a so-called thermotropic liquid crystalline wholly aromatic polyester capable of forming an anisotropic molten phase.

Of these wholly aromatic polyesters, hydroxybenzoic acid, especially a polyester of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, and further, p,
Polyesters comprising p-hydroxybenzoic acid, p, p'-biphenyl, terephthalic acid and / or isophthalic acid, in addition to polyesters copolymerized with p'-bisphenol as the third component, are useful, but are not limited thereto. It does not hinder the introduction of other components into the polymer, as long as the object of the present invention is not hindered.

Generally, these wholly aromatic polyester fibers have the following physical properties.

Particularly, a monomer mainly composed of a copolymer of p-hydroxybenzoic acid and 6,2-hydroxynaphthoic acid has the following physical properties.

Next, the heat treatment conditions will be described in detail. First, the heat treatment temperature is preferably in the range of the melting point of the wholly aromatic polyester and a temperature 50 ° C. lower than the melting point. The melting point of the wholly aromatic polyester increases as the heat treatment proceeds. Accordingly, a method of increasing the heat treatment temperature as the heat treatment proceeds may be used. The heat treatment time is preferably 1 minute to 100 hours, particularly preferably 5 to 50 hours. The heat treatment may be carried out in a state of being wound on a bobbin, in a free state on a net-like material, or by a method of running on a heating roller. The condition of a fineness of 1 to 3000 deniers is a preferable 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 so as to enhance the adhesive force with the resin. From the viewpoint of surface area, fine denier of less than 1 denier is more preferable, but there is a problem in spinning conditions, and further, it is not preferable because the fiber alignment during drawing and the volume% of the fiber after resin impregnation are reduced. On the other hand, over 3000 denier, high strength,
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. A variety of thermosetting resins can be selected, but the reinforcing bars used for cement concrete and the tensile material for prestressed concrete are used in cement alkali. It cannot be used if it peels off at the bonding interface with it.
In addition, it is necessary to use a heat-resistant resin for reinforcing materials of transmission lines and optical fiber communication cables.
In addition, thermosetting resin is used in that it can sufficiently exert the force as a bundle when the fibers are bundled, and among them, epoxy resin is preferable for a cement concrete reinforcing material or a tensile material. Among them, glycols, polyglycidyl ether compounds obtained by reacting epichlorohydrin with polyols, or phenols, monoglycidyl ether compounds obtained by reacting alcohols with epichlorohydrin, typically bisphenol A and epichlorohydrin The glycidyl ether obtained from the condensation reaction is used. In addition, melamine-formalin-based, phenol-based, and urea-based thermosetting resins can be used. In addition, in order to reinforce a cable or the like, an unsaturated polyester resin or a wholly aromatic polyester resin can be used in addition to the above-mentioned resins. Fiber content volume in resin is 60
%, Because the strength of the fiber is used as a reinforcing material, and the smaller the resin that is a matrix component, the less the tensile strength and Young's modulus of the composite It is clear that will increase. In the present invention, the volume occupied by the fibers in the composite material is 60%
Otherwise, the mechanical properties such as the fiber strength and Young's modulus are reduced, and it is meaningless. In addition, in the draw molding, the resin is more desirable for suppressing the infiltration of air when the fiber passes through the inside of the drawing nozzle and for forming the lubrication, but satisfies the mechanical properties of the composite. Therefore, it is necessary to reduce the resin amount to 40% or less. The form of the fiber aggregate in the composite has important significance when used as reinforcement or tensile material. That is, if the orientation of the fibers in the pultruded rod is not 50% or more, preferably 70% or more, in the fiber direction, no matter how perfect the bonding is, the tensile stress applied to the aggregate of the fibers is reduced to a single fiber. It is considered that the stress received by each fiber is different even if they are allotted to each other, so that the fiber aggregate does not exert 100% force, but can exert only 30 to 50% force.

As a conventional technique, a method of producing a reinforcing fiber bundle by twisting fibers to form a bundle and then impregnating with an adhesive resin is known. In a fiber bundle obtained by this method, a single fiber generally does 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, 50 of the fibers
It is important that more than one percent are substantially completely aligned.

In addition, take an arbitrary part of the pultruded molded product with a length of 1 cm, cut it in parallel to the fiber axis direction, and count the number of alignments in the fiber molding axis direction in the cutting plane with a microscope to determine the ratio of alignment by drawing Can be. In order to control the fiber alignment and to minimize the creep after loading, the resin is impregnated by applying a tension with a molding nozzle so that the elongation ratio becomes 0.05 to 2% after impregnating the resin. % Of the fibers can be formed while being 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, as a substitute for a reinforcing steel bar for concrete, it is necessary to form protrusions on the rod-like surface in the same manner as the deformed reinforcing steel bar in order to mechanically impart adhesiveness to concrete with a diameter of 6 to 60 mm. The present inventors need a denier thickness of 1 to 5% of the total fineness at the time of molding a molded rod,
Consisting of wholly aromatic polyester-based synthetic fibers, polyvinyl alcohol-based synthetic fibers, and aramid-based synthetic fibers with 50-200 twists per meter to enhance deformability, and those impregnated with the resin used at the time of pultrusion molding, It is found that a deformed rod can be obtained by a method of winding and heat-treating and joining two rods so that the rod after drawing is obliquely inclined at an angle of 40 to 50 ° with respect to the axial direction. Was. The winding pitch is called a diagonal pitch, and the value obtained by dividing the average pitch of the pitch by the diameter of the rod is preferably 0.6 to 0.8, and most preferably about 0.7.

Next, the production method of the present invention uses a molten liquid crystal polymer composed of a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid to perform melt spinning to obtain a spun yarn of 1 to 3000 dr. Further, by performing a heat treatment in air at 290 ° C. for 24 hours or more, a wholly aromatic polyester fiber having a strength of 15 g / dr or more, an elongation of 4% or less, and a Young's modulus of 300 g / dr or more can be obtained.

The fiber is wound in a cheese form as a yarn or monofilament of 250 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 a drawing molding nozzle. The resin is pulled out while adhering and defoaming while passing through a heating furnace at 130 to 250 ° C. The resin is cured and molded by heating. The thread alignment between the resin impregnation tank and the hot drawing must be perfect, and 0.05 to 2% of the fiber must be used to achieve a 50% or more drawing alignment at the time of drawing.
It is necessary to mold while applying a tension to give a 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.

<Operation> As a reinforcing material according to the present invention, it can be used as a reinforcing steel substitute for mortar 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 a reinforcing material for PC steel wire, power transmission cable and optical fiber communication cable, as well as a wire material having 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.

 Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1 Using a molten liquid crystal polymer comprising a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid,
Melt spinning was performed to obtain a spinning original yarn of 1500d / 300f. 2 at 290 ° C
Heat treatment was performed in air for 4 hours to obtain a heat treated yarn of 1500d / 300f. The single fiber denier is 5 denier, tensile strength 24.3
g / dr, elongation 3.4%, Young's modulus 600g / dr.

The 160 cheese fiber was attached to a creel equipped with a tension controller, and the total denier was set to 240,000 denier. The denier was carefully introduced into a rotary dipping roll so that the tow was not disturbed in an epoxy resin (Epicoat 828 manufactured by Yuka Ciel Epoxy) impregnation tank. The resin adhesion was reduced to 30%, and the volume% of the fiber was 70%. A pultruding nozzle having a circular diameter of 6 mm was used. The curing temperature of the resin is 180 ° C, 3 minutes per minute
Molding was performed with m. Further, the drawing roll after heat curing had a drawing tension giving a speed difference of 0.7% of that of the date roll. The molded rod was cut out 1 cm, and the alignment of the fibers was observed under a microscope. It was observed that an average of 85% or more was aligned in the fiber axis direction.

As Comparative Example 1, aramid fiber (Dupont's Kepler 29,1500dr / 1000f) fineness 15 denier, tensile strength 21 g
/ dr, 3.9% elongation, and 470 g / dr of Young's modulus were molded in exactly the same manner as in Example 1 using 168 cheese. In order to impart deformability, Example 1 and Comparative Example 1 used two 1500 denier yarns made of polyvinyl alcohol fiber, and
The same epoxy resin as that of the pultruded product was impregnated 120 times, and was wrapped clockwise and counterclockwise at intervals of 8.5 mm with respect to the axial direction, and further thermally bonded at 180 ° C.

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

The creep performance of the fibers used in Example 1 and Comparative Example 1 was measured according to JIS-L-1017. The initial load was 1/30 of the breaking strength and the load was 1 / 3.5 of the breaking strength. The specimen 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 1 is a fiber having high strength and high Young's modulus, stress relaxation occurs for a long time, which is not preferable as a tensile material or a reinforcing material.

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

The cement mortar used in Example 2 and Comparative Examples 2, 4, and 6 was 100 parts by weight of early-strength cement (Asano early-strength cement) (hereinafter, all parts by weight), 300 parts of quartz sand (Inkstone silica sand No. 6.5), and gravel (Okayama). 150 parts of Asahikawa (5 mm or less in particle diameter) were weighed, and dry mixing was performed for 1 minute with an omni mixer, and 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 blending of the lightweight cement mortar used in Example 3 and Comparative Examples 3, 5, and 7 was made of an early-strength cement (Asano early-strength cement).
0 parts, 10 parts of fine powder pearlite (Ube 1 type), expander (# 20 manufactured by Denki Kagaku Co., Ltd.) are added, and dry-mixed with an omni mixer for 1 minute, and a foaming agent (formix manufactured by Hamano Industry Co., Ltd.)
C2) 3 parts and 1 part of a water reducing agent were added and mixed with an omni mixer for 2 minutes to obtain a mortar.

For molding, use a standard formwork of 10cm x 10cm x 40cm, and apply two pieces in the longitudinal direction (bar arrangement ratio 0.28%) so that the cover thick soil becomes 1cm.
The distance was fixed at cm. 10cm × 10cm × 40 for those not arranging
The cm frame was used as is.

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

As for the training, in Example 2, Comparative Examples 2, 4 and 6, curing was allowed to stand at room temperature all day and night, followed by demolding and curing in water 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 3, 5, and 7 were left at room temperature for 24 hours, then removed from the mold, and then left to stand in the air for 4 weeks.

The bending strength was measured by a universal tester manufactured by Shimadzu. The maximum breaking load and its deflection were measured by a central loading method with a span length of 30 cm. 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). They are shown in Table-3.

Example 2 is Comparative Example 6 for reinforcement of cement mortar
5 times or more as compared to Comparative Examples 2 and 4, and also excellent in durability. Example 3 is superior to other comparative examples also in reinforcing lightweight cement mortar.

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Claims (2)

(57) [Claims] (1) a fineness of 1 to 3000 denier and a tensile strength of 15
g / dr or more, a wholly aromatic polyester synthetic fiber having a Young's modulus of 300 g / dr or more is composed of a thermosetting resin in an amount of 60% by volume or more, and 50% or more of the wholly aromatic polyester synthetic fiber is a fiber aggregate. A bar-shaped reinforcing material that is aligned in the drawing direction of the rod and exists in a straight state without substantially being twisted. 2. A tensile strength of 15 g / dr or more and a Young's modulus of 300 g.
/ dr or more, monofilament fineness is impregnated with a thermosetting resin with a wholly aromatic polyester synthetic fiber with a denier of 1 to 3000
The fiber is heat-molded so that the fiber content is 60% by volume or more while giving a tension of 0.05 to 2%, wherein 50% or more of the wholly aromatic polyester-based synthetic fibers are fiber aggregates. A method for producing a rod-shaped reinforcing material which is aligned in the body-drawing direction and exists in a straight state without substantially twisting.