JPH03249287A - Twisted structure made of fiber-reinforced thermosetting resin and its production - Google Patents

Abstract

PURPOSE:To efficiently obtain the subject structure by impregnating filamentary reinforcing fiber with a thermosetting resin, drawing the resultant fiber to a required shape, passing the formed fiber through a crosshead die, coating the fiber with a meltlike thermoplastic resin, twisting and curing the formed composite strands. CONSTITUTION:Filamentary reinforcing fiber (G) arranged on a rack 2 is doubled and bundled with a guide 3, then led into a resin bath 4 and impregnated with an uncured thermosetting resin, drawn to a required shape with a drawing nozzle 5, subsequently passed through a crosshead die 6, coated with a thermoplastic resin 21 having a softening point or melting point near the curing temperature and cooled in a cooling bath 7 to provide a core strand (S0). Strands (S1) to (S6) for the outer periphery are prepared by impregnating plural reinforcing fibers with a thermosetting resin in the same manner as that in the core strand (S0) and then coating the strands with a thermoplastic resin 22, compatible with the thermoplastic resin in the core strand and having a higher softening point than the curing temperature thereof. The aforementioned core strand (S0) is then placed in the center and the internal thermosetting resin is cured in a curing bath 10 while twisting the plural outer peripheral strands (S1) to (S6) on the outer periphery thereof to afford the objective structure.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fiber-reinforced thermosetting resin twisted structure of a type in which a predetermined number of outer peripheral strands are spirally twisted around the outer periphery of a central core strand; The present invention relates to a method of manufacturing the same, and particularly to a twisted structure suitable for a tensile reinforcing material such as a rock bolt, and a method of manufacturing the same.

(Prior art and its disadvantages) A twisted structure made of fiber-reinforced thermosetting resin (hereinafter referred to as FRP) has the following properties: lightweight, corrosion resistance, elastic recovery, flexibility, non-induction, insulation, and easy cutting. Because it has the following characteristics, it can be expected to be used in applications that take advantage of these characteristics.

Applications that take advantage of the above characteristics include rock bolts and earth anchors, which are used as reinforcing materials in civil engineering works such as tunnel excavation to prevent collapse and spalling of the ground.

When using FRP twisted manufacturing structures for these applications, it is important to consider the following characteristics: ease of insertion into holes drilled in the ground, ease of insertion after pre-filling a fixing agent such as mortar, and expansion of the tunnel after insertion and fixation. It has the advantage of being easier and safer to cut depending on the diameter etc. than conventional metal rock bolts, and its use is recommended from the viewpoint of workability and safety.

The present applicant has already published U.S. Pat.
No. 9500.

However, in these twisted structures of the prior application, the thermoplastic coating layers of the composite strands are longitudinally fused at their contact points, and the FRP outer periphery of the outer strand and the coating are anchored effectively. As a result, the bending rigidity of the twisted structure becomes large, and when winding it up on a winding drum after twisting and hardening, the winding diameter must be made considerably large. Problems arose in terms of winding equipment, transportation costs, etc.

Therefore, the present inventors developed a twisted structure of a type in which outer strands are twisted around a core strand around the outer periphery of the core strand, which prevents the strands from coming apart during handling, etc., and has flexibility. The present invention was completed after intensive study on a structure that can be easily rolled up onto a drum, etc., and a rational manufacturing method.

(Structure of the Invention) The twisted structure according to the present invention is a composite strand in which a reinforcing fiber material is impregnated with an uncured thermosetting resin, and then drawn and formed, and a thermoplastic resin coating layer is provided on the outer periphery of the composite strand. In a twisted structure having a core strand and an outer strand, the outer strand is twisted around the outer periphery of the core strand and hardened, wherein the thermoplastic resin of the core strand softens less than the thermoplastic resin of the outer strand. and has a low melting point and is compatible with the thermoplastic resin of the outer strand, and the coating layer of the core strand and the coating layer of the outer strand are bonded to each other at their contact portions. shall be.

In addition, as a manufacturing method for the twisted structure having the above configuration, long reinforcing fibers are impregnated with an uncured thermosetting resin, drawn into a desired shape, and then inserted into a crosshead die. In a method for producing a twisted structure, in which a composite strand is annularly coated with a molten thermoplastic resin and has an uncured interior, and the composite strand is twisted and cured, the step of obtaining the composite strand includes the production of a core strand. The core strand manufacturing process consists of coating the core strand with a thermoplastic resin having a softening point or melting point near the curing temperature, and cooling and solidifying this coating. is compatible with the thermoplastic resin of the core strand, and
The core strand is coated with a thermoplastic resin having a softening point higher than its curing temperature, and this coating is cooled and solidified.Continuously in each of these manufacturing steps, the core strand is supplied to the center, and the required number of core strands are added to the outer periphery. a twisting and curing step of curing the uncured thermosetting resin inside while twisting the outer peripheral strands, and in the curing step, the covering of the core strand and the covering of the outer peripheral strand are bonded together at their contact portions. It is characterized by adhesion.

Reinforcing fiber materials that can be used in the present invention include long fibers with high strength and low elongation such as glass fibers, aromatic polyamide fibers, carbon fibers, and various synthetic fibers. Examples include unsaturated polyester resin, phenol resin 1, and the like.

The thermoplastic resin used for the core strand is a resin that has a softening or melting point near the setting temperature of the curing tank that is heated to cure the thermosetting resin, and the thermoplastic resin for the outer strand is The material is selected from materials that have a softening point at which the thermoplastic resins of the outer strands do not fuse together at the curing temperature and are compatible with the thermoplastic resin used for the core strand.

For example, considering thermal efficiency in the curing process, it is desirable to use hot water or steam as the heat medium, and based on these temperatures, vinyl acetate resin, ethylene ethyl acrylate resin Modified polyethylene resins such as , adhesive polyethylene and the like are suitable, and these resins may be used alone or in combination.

On the other hand, the thermoplastic resin of the outer strand is a polyethylene-based resin that is compatible with the above-mentioned resins, such as high-density polyethylene and low-density polyethylene.

Linear low density polyethylene etc. can be used.

When using these thermoplastic resins for the outer strand and fusing or bonding only the contact area with the thermoplastic resin of the core strand, the FRP outer periphery of the outer strand and the inner periphery of the coating layer should be Since the fibers do not adhere to each other due to an anchor effect or the like, the resulting twisted structure can be made even more flexible.

In the manufacturing method of the present invention, long reinforcing fibers are impregnated with an uncured thermosetting resin, drawn, and then coated in a ring shape with a molten thermoplastic resin. The composite strand, which is made by cooling the FRP and coating the internally uncured FRP with a thermoplastic resin, was disclosed in Japanese Patent Publication No. 51, which was filed in the applicant's earlier application.
A known method based on No. 43501 can be used, but since the core strand and the outer strand are coated with different thermoplastic resins as described above, one feature is that the coating steps are performed in parallel.

In addition, the process of twisting the outer strand around the core strand that has undergone the coating process and the curing process are directly connected to the coating process,
It is characterized in that the curing is carried out under temperature conditions such that the thermoplastic resin of the core strand and the thermoplastic resin of the outer strand fuse or adhere at their contact points.

(Function) In the twisted structure of the present invention, since the core strand and the outer strand are joined only at the contact portion of their coating layer, the outer strand can be freely displaced when bent. Even the contact portion of the conventional outer circumferential strand can be bent with less force than in a joined structure, and the bending diameter can also be made smaller, so a continuous length can be easily wound onto a drum or the like.

When used as a rock bolt or the like, an effective locking force can be exerted between this twisted structure and a fixing agent such as cement mortar due to the unevenness effect due to the twisted structure of the outer periphery strand.

Furthermore, according to the method of the present invention, the manufacturing process of the core and outer composite strands, the twisting process, and the curing process are directly connected, so there is no need for winding in the middle, which was a problem in the past. The twisted structure of the present invention can be efficiently manufactured while solving the problem of the pot life of the thermosetting resin in the uncured composite strand.

(Example) Hereinafter, the present invention will be explained using preferred embodiments.

*Example A 1×7 type twisted structure in which the composite core strand and outer strand were coated differently was manufactured in the following manner for the purpose of making a rock bolt.

■ Manufacturing process of core strand SO After binding glass fiber roving (Nittobo Co., Ltd.: R5220) as reinforcing fiber G on the shelf 2 with the guide 3, uncured unsaturated polyester resin (Mitsui Toatsu Chemical The resin was introduced into a resin bath 4 containing a mixture of Ester 1-8100 (manufactured by Ester) and a peroxide catalyst for curing, impregnated with uncured resin, drawn to an outer diameter of 6°5 am with a drawing nozzle 5, and then melt-extruded. After passing through the die part of machine 6 and coating it with vinyl acetate resin (hereinafter referred to as EVA) (manufactured by Ube Industries: V-125) to which 1 part of black masterbatch was added (manufactured by Ube Industries: V-125), it was cooled immediately. The EVA resin coating layer on the surface was cooled by passing through a water tank 7, and then taken off by a Nelson roller 8.

■Production process for outer strands 81 to S6 The six outer strands for outer strands 81 to S6 are made of the same glass fiber and unsaturated polyester resin as the core strand SO.
The glass fiber G placed on the guide 3' and the resin bath 4
' and drawn to the same size with a drawing nozzle 5', low-density polyethylene (manufactured by Ube Industries: B -028), outer diameter 7.5m
Covered in a ring shape of m, each of the 6 pieces was covered with a Nelson roller of 8
' was taken over.

■Twisting/hardening process The core strand SO taken up by the Nelson roller 8 is guided through the guide roller 20 to the manufacturing process of the outer strands 81 to S6, and placed in the center of the guide 9a, while on both sides. 3 outer strands each
1-S3. S4 to S6 are arranged, and furthermore, a guide 9b and a curing tank 10 in which hot water of 95° C. is circulated. Cooling water tank 1
1□Rotary winding machine 121 After passing through the rotary winding machine 13, hardening and cooling while twisting, a drum having a drum diameter of 1200 mm was wound up.

The resulting twisted structure for rock bolts consists of each strand S
The glass fiber volume content of O, Sl to S6 is 53%, the twist pitch is 25.0rrrts, and the tensile strength is 20 tons, and its cross-sectional structure is as shown in Figure 3.
EVA coating layer 21 of O and P of outer strands S1 to S6
The E coating layers 22 were fused to each other only at their contact portions, and the PE coating layers 22 of the outer strands S1 to S6 were not fused to each other.

Note that the inner periphery of the PE coating layer 22 of the outer periphery strands S1 to S6 and the outer periphery of the fiber-reinforced thermosetting resin are not fused to each other, and the flexibility of the twisted structure can also be improved in this respect.

*Comparative example In comparison with the above example, a twisted structure was obtained using the same EVA resin as the core strand SO for the coating resin of the outer strand.
The covering portions 1 to S6 cover not only the contact portions between the core strand SO and the outer strands 81 to S6, but also the outer strands 8
A product was obtained in which the contact portions of No. 1 to S6, the inner periphery of each covering portion, and a portion of the FRP outer periphery were also fused and bonded to each other.

The twisted structure in this comparative example had significantly increased bending rigidity, and it was difficult to wind it up onto the above-mentioned 1200 m diameter drum.

(Effects) As described above in detail in Examples and Comparative Examples, the twisted structure of the present invention uses a composite strand in which the outer periphery of a fiber-reinforced thermosetting resin is coated with a thermoplastic resin, and the core strand The outer sheathing of the outer strand and the outer sheath of the outer strand are joined only at the contact area, allowing the strands to behave as one as a twisted structure without coming apart, while being flexible enough to be wound onto a drum, etc. It can be used as a rock bolt of irregular length or an earth anchor.

In addition, the method for producing a twisted structure of the present invention involves sequentially twisting, curing, and winding from the production of uncured composite strands. A twisted structure can be manufactured efficiently without having to consider storage stability.

[Brief explanation of drawings]

FIG. 1 is a plan view sequentially showing the steps of the manufacturing method according to the present invention, FIG. 2 is a partial side view of the same method, and FIG. 3 is a sectional view showing an example of the twisted structure of the present invention. SO・・・・・・Core strand

Claims (3)

[Claims] (1) It has a core strand and an outer strand made of a composite strand in which a reinforcing fiber material is impregnated with an uncured thermosetting resin, and then drawn and formed, and a coating layer of a thermoplastic resin is provided on the outer periphery of the composite strand, In the twisted structure in which the outer periphery strand is twisted around the outer periphery of the core strand and cured, the thermoplastic resin of the core strand has a lower softening point or melting point than the thermoplastic resin of the outer strand, and A twisted structure made of fiber-reinforced thermosetting resin, which is compatible with the thermoplastic resin of the strands, and characterized in that the covering layer of the core strand and the covering layer of the outer strand are bonded to each other at their contact areas. body. (2) The thermoplastic resin of the core strand is selected from modified polyethylene resins such as vinyl acetate resin, ethylene ethyl acrylate resin, and adhesive polyethylene resin.
or a mixture thereof, and wherein the thermoplastic resin of the outer strand is selected from polyethylene resins such as high-density polyethylene, low-density polyethylene, and linear polyethylene. Reinforced thermoset resin stranded structure. (3) Long reinforcing fibers are impregnated with uncured thermosetting resin and drawn into the desired shape, then inserted into a crosshead die and coated with molten thermoplastic resin in an annular shape. A method for manufacturing a twisted structure in which a composite strand with an uncured interior is obtained, and the composite strand is twisted and hardened, the step of obtaining the composite strand comprising a core strand manufacturing process and an outer periphery strand manufacturing process. In the manufacturing process of the core strand, the core strand is coated with a thermoplastic resin having a softening point or melting point near the curing temperature, and this coating is cooled and solidified, and in the manufacturing process of the outer peripheral strand, the core strand is heated. The core strand is coated with a thermoplastic resin that is compatible with the plastic resin and has a softening point higher than its curing temperature, and this coating is cooled and solidified. supplying the core strands to the center, and curing the uncured thermosetting resin inside while twisting a required number of the outer periphery strands around the outer periphery, and in the curing step, coating the core strands. A method for producing a twisted structure made of fiber-reinforced thermosetting resin, characterized in that the outer strand is bonded to the covering of the outer strand at the contact portion thereof.