JPH02259178A - Twisted structure made of fiber-reinforced thermosetting resin and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject structure resistant to the lowering of tensile strength caused by twisting by impregnating uncured thermosetting resin into a reinforcing fiber raw material, covering the outer circumference of the material with a thermoplastic resin and twisting the resultant composite strands at a specific twisting pitch. CONSTITUTION:An uncured thermosetting resin is impregnated into a reinforcing fiber raw material 1 with a resin bath 4 and the impregnated material is passed through a die of a melt extruder 6 to cover the material with a thermoplastic resin in an annular form. The covered material is cooled in a cooling tank 7. Each of a plurality of the obtained composite strands S1 to S7 is separately taken up with a take-up roller 8 while controlling the take-up speeds of the core strand and the circumferential strand, passed through guides 9a, 9b, a hot water curing tank 10, a hot air drier 11 and a rotary take-up machine (twisting machine) 12, twisted at a twisting pitch corresponding to >=25 times the outer diameter of the uncured filament of the composite strand by rotating the rotary take up machine 12, wound with a rotary winder 13 and further cured to obtain the objective structure.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a twisted structure made of fiber-reinforced thermosetting resin that has both high tensile strength and flexibility and is suitable as a tension member of a non-metallic optical cable. and its manufacturing method.

(Background of the invention) In recent years, there has been an emphasis on non-guidance and lightweight communication cables, and there has been a large movement to shift from metallic cables to non-metallic cables.As a result, glass fibers have been used as tension members. Also, rod-shaped objects made of fiber-reinforced thermosetting resin (hereinafter referred to as FRP) using aramid fibers as reinforcing fibers have come to be widely used.

However, when considering an FRP rod-shaped object whose tensile performance is comparable to that of a metallic tension member (steel wire, stranded steel wire), its outer diameter is inevitably large, and as a result, the rigidity is higher than necessary. It became a cable, and there was a big problem in terms of handling.

Therefore, we considered obtaining flexibility while maintaining tensile performance by twisting multiple linearly hardened FRP rods, but the strands that make up the twisted wires repel each other and the twists come apart. An easy and stable twisting state could not be obtained.

Furthermore, when producing twisted wire, it is necessary to wind the hardened FRP wire as a strand around a bobbin and feed it while rotating, but this makes the twisting process complicated and increases costs.

On the other hand, in order to obtain a rope-like object made of FRP, reinforcing fibers are impregnated with an uncured thermosetting resin, molded to a predetermined outer diameter, and then covered with a thermoplastic resin to obtain a composite strand. A method of curing after twisting in the twisting process is known.

However, in the conventional method for producing rope-like products using composite strands, the production of uncured composite strands and the steps of twisting and curing are performed in separate processes, so the storage stability of the uncured thermosetting resin is There have been problems with the properties of the composite strands, and during the process of winding them onto drums, bobbins, etc., the reinforcing fibers in the composite strands become lopsided or disordered, resulting in deterioration of physical properties after curing.

Therefore, the present inventors have developed a structure and method that can overcome the above-mentioned problems, that is, an FRP twisted manufacturing structure that has flexibility due to the twisted structure, and has stability in twisting, productivity, and high strength. The present invention was completed after intensive study of the method of manufacturing the same.

(Structure of the Invention) In order to achieve the above object, the twisted structure of the present invention has a reinforcing fiber material impregnated with an uncured thermosetting resin, and the outer periphery of the uncured filament is coated with a thermoplastic resin. A twisted structure made by twisting together a plurality of composite strands and curing them, which consists of a core strand arranged at the center and outer peripheral strands twisted in the same direction at a predetermined twisting pitch around the outer periphery of the core strand. , the twisting pitch is 25 times or more the outer diameter of the uncured filament of the composite strand.

The reinforcing fiber materials that can be used in the present invention are of any type as long as they have tensile strength, but include continuous glass fibers, aromatic polyamide fibers, carbon fibers, nylon, polyester, vinylon, etc. Synthetic fibers include: The fiber content is approximately 50 to 75 vo
ρ%, more preferably 55 to 70voρ%. Further, as the thermosetting resin, unsaturated polyester resin is generally used, but epoxy resin 1, phenol resin, etc. may also be used.

The type of thermoplastic resin that covers the reinforcing fibers and the uncured thermosetting resin impregnation is not particularly limited as long as it can be easily coated by melt extrusion, but in general, it is flexible and durable. Polyethylene-based resins and polyamide resins are recommended as flexible resins due to their low-temperature physical properties and economic efficiency.

The twisting pitch of the outer strand, which is twisted around the outer periphery of the core strand placed in the center, is at least 25 times the outer diameter of the uncured filament of the composite strand used for the outer periphery, in order to maintain physical properties such as strength retention. must be done.

When manufacturing a fiber-reinforced thermosetting resin twisted structure, the method for manufacturing uncured composite strands is based on the method disclosed in Japanese Patent Publication No. 51-43501 filed by the present applicant. A few strands of the twisted structure are simultaneously coated with a thermoplastic resin, the coating layer is immediately cooled, and immediately thereafter the twisting process begins.

In the twisting, the central core strand and the outer peripheral strand to be twisted around its outer periphery are first passed through a guide, and then hardened while being twisted in a heating curing tank disposed between the guide and the rotary twisting machine. Alternatively, it may be cured in the curing tank after being twisted outside the curing tank.

When twisting, especially when the tension of the core strand is Tc and the tension of the outer strand is To, it is important to keep To less than Tc in terms of tensile strength retention after curing and bending resistance. preferred.

It is preferable that the curing after twisting be carried out at a temperature below the softening point of the thermoplastic resin coating layer of the composite strand, in order to impart sufficient flexibility to the twisted structure after curing.

Furthermore, when a thermoplastic resin coating is applied to the outer periphery of a twisted structure after the stranded wires have been cured, and a liquid heat medium is used to cure the stranded wires, liquid may enter between the composite strands of the stranded wires. If a thermoplastic resin coating is applied with liquid remaining, the liquid may boil and cause problems such as unevenness on the coating surface.

From this point of view, when using a liquid heat medium such as boiling water to harden the strands, after twisting the uncured composite strands and before curing, a thermoplastic resin coating is applied to the outer periphery of the stranded structure, and then It is desirable to cure the uncured resin inside.

(Example) The present invention will be explained below using preferred embodiments.

Example 1 In order to obtain a 1×7 FRP twisted structure, glass fiber roving (Nittobo Co., Ltd. 280 Tex) was placed as the reinforcing fiber G on the shelf 2 for seven strands, and the guide 3
is introduced into a resin bath 4 containing a mixture of an uncured unsaturated polyester resin (Ester H8100 manufactured by Mitsui Toatsu Chemical Co., Ltd.) and a peroxide catalyst for curing, and the reinforcing fibers G are impregnated with the resin. An uncured filament with a diameter of 1.2 mm,
This was passed through the die part of the melt extruder 6, and the outer periphery of each uncured filament was heated by adding 3 parts of a black masterbatch to low-density polyethylene (MG211. manufactured by Nippon Unicar) with a softening point of 97°C. A primary coating layer C1 was formed by coating with a plastic resin in an annular manner, and the primary coating layer C1 on the surface was immediately cooled in a cooling bath 7 to obtain seven composite strands S] to S7. Note that the outer diameter of the composite strands S1 to S7 at this stage was 1.5++nn. Subsequently, composite strands 81 to S7 were twisted together in the following manner.

First, the composite strands 81 to S7 are taken off by individual take-off rollers 8 while adjusting the take-up speed of the core strand and the take-up speed of the outer peripheral strand whose length changes due to twisting, and each strand 81 to S7 is prepared as a reserve. It is inserted through the guide 9a and the guide 9b, and the softening point 9 of the primary coating layer is reached.
Hot water curing tank 1 whose temperature is controlled to 95℃ at a temperature of 7℃ or less
0, a hot air dryer 11, and a rotary pulling machine (twisting machine) 12 in order, and then the rotary pulling machine 12 was rotated for twisting.

When twisting, the central composite strand S4 is used as the core strand, and the remaining six strands are used as the outer strands S1 to S3.
．． It was set as S5 to S7.

In this case, in order to adjust the tension of the strands 81-S7, each strand 81-S7 is placed between the guides 9a and 9b.
A dancer roller 15 is placed on each S7,
The tension of the core strand S4 was 1 kg, and the tension of the outer strands S1 to S3. Each tension of S5 to S7 is 0.3kg
control, and the twist pitch is composite strand 81~S.
The target was 60 mm, which was 40 times the outer diameter of No. 7 and 50 times that of the uncured filament.

After being twisted under the above conditions, the hardened twisted structure (twisted filament) was then wound up using a rotary winding machine 13 equipped with a winding bobbin.

The resulting stranded wire was further post-cured at 80° C. for 24 hours.

The resulting twisted wire with a 1×7 twisted structure has an apparent outer diameter of 4.5
~4.6mm, twist pitch 60±10mm, glass fiber content of 5FRP part 65'voΩ%, tensile strength 880~9
50kg, strength 200kg at 0.5% elongation, unit type 1
7, 2 L, 8 g/m.

The stranded wire according to this example has a strength reduction rate of about 30% of the theoretical value when it is hardened in a straight line without twisting, and the bending rigidity is
The force required to bend a piece of m+* to a bending diameter of 200 mm is 450 g, which is about 1/6 of the bending rigidity of a single rod-shaped piece of FRP with a corresponding cross section. Moreover, the minimum bending diameter was 9' 5 +nm.

In addition, after twisting the stranded wires of this example, and before hardening, a secondary coating layer C2 was formed on the outer periphery using low density polyethylene or nylon 12, and the outer diameter was set to 5.5 mm, and the minimum bending diameter of these was measured. However, with the former covering, it is 75mm
, the latter was 80 mm.

Example 2 A stranded wire was manufactured using the same uncured composite strands 81 to S7 as in Example 1, with a twisting pitch of 120 mlB, and using a method different from Example 1 only in the twisting process.

Regarding uncured composite strands having an outer diameter of 1.5+nm that are continuously produced, only the core strand S4 is taken off by a Nelson type take-off roller 8, and the core strand S4 and the outer circumferential strands S1 to S3. Through S5 to S7, the material was cured while being twisted by the rotary take-up machine 12 in the same manner as in Example 1, wound up by the rotary wind-up machine 13, and then post-cured under the same conditions as in Example 1 (see Fig. 3). ).

The tension of core strand S4 in the twisting process is 3k.
Adjust the load of the dancer roller so that the outer strands S1 to S3. For the tensions S5 to S7, the take-up resistance value before guide 9 is 1, . It was 5 kg.

Note that the tension of the strands can be adjusted by the reinforcing fiber content of the core strand and the outer strand or the viscosity of the uncured resin.

The resulting twisted wire with a 1×7 twisted structure has an apparent outer diameter of 4,
5-4, 6 in, twist pitch 120±10 myn.

Unit weight 21.6g/m, minimum bending diameter 80m.

Tensile strength 840~i 020'kg, 0. The strength at 5% elongation was 210 kg, the bending rigidity was 450 t, and the tensile strength reduction rate was 28.6%.

Experimental Results I Using the uncured composite strands with an FRP outer diameter of 2.5 mm and a coated outer diameter of 3.0 mm, a stranded wire with the same 1×7 twist structure as in Example 1 was woven into glass by the method of Example 1. It is manufactured by changing the fiber content, the twisting pitch expressed as a ratio to the outer diameter of the uncured filament, the ratio of the outer tensile tension to the twisting tension of the core strand, etc. A coated stranded wire was then obtained.

Table 1 shown below summarizes the conditions of the above examples and comparative examples.

As is clear from these results, when the twist pitch is 2o times the outer diameter of the composite strand, it will break when bent, and the twist tension of the outer strand is 1/3 of the core strand tension of 3.7 kg. degree or suitability;
It was also confirmed that bending resistance could be improved by secondary coating.

Experimental Results 2 In order to investigate the effect of the temperature when curing the FRP uncured linear objects in the composite strand on the physical properties of the twisted structure, we varied the curing conditions and the thermoplastic resin material of the next coating layer. A sample was created.

Curing was carried out by passing through a bath filled with silicone oil. All samples were 1×7 type twisted structures, and no sheath was provided.

Table 2 shows the results of measuring the adhesive strength between the FRP strands in the composite strand and the coating layer and the bending rigidity of the twisted structure for these samples. Adhesive strength is expressed as the force required to peel off a part of the coating layer from the FRP wire by pulling the remaining end in the opposite direction at a speed of 50 mm/min. In addition, the bending rigidity was determined by cutting each sample into a length of 400 mm, and cutting this into a length of 250 +++ m in diameter.
The force required to bend it into a semicircular shape was measured using a platform scale.

These results show that when the FRP wire is cured at a temperature below the softening point of the thermoplastic resin coating layer, a wire with low bending rigidity can be obtained.

(Blank below) (Effects of the invention) The twisted structure of the present invention consists of composite strands made by impregnating a reinforcing fiber material with an uncured thermosetting resin and covering the outer periphery with a thermoplastic resin, which are twisted at a predetermined pitch. Since the wires are twisted together, a high-strength product with a small rate of decrease in tensile strength due to twisting can be obtained, and the bending resistance can be improved.

Furthermore, if the entire twisted structure is coated with a thermoplastic resin, the bending resistance can be further improved.

On the other hand, according to the method of the present invention, since the required number of uncured composite strands are manufactured and then twisted under predetermined conditions, the above-mentioned twisted wire with high physical properties can be obtained, and the composite strand can be manufactured. The process is significantly streamlined compared to the conventional method, which separates the process into multiple steps, such as twisting, twisting, and curing, and also reduces the storage stability and physical properties of uncured composite strands when divided into multiple steps. Such problems can also be overcome.

The above-described twisted structure according to the present invention can be used as it is or with a secondary coating, as a tension member of an optical fiber carrying space used as an element of an optical fiber cable, or as a secondary coating on the outer periphery of the twisted structure. It is extremely useful as it can be used as a tensile strength material with high tensile strength and flexibility by coating it to form a perfect circle and arranging optical fiber core units in a spiral around the outer periphery of this tension member. .

[Brief explanation of drawings]

Fig. 1 is a plan view of the manufacturing method according to the present invention, Fig. 2 is a side view of the same method, Fig. 3 is an explanatory diagram of main parts showing another example of a means for adjusting the tension of a composite strand, and Fig. 4 is a plan view of the manufacturing method according to the present invention. FIG. 1 is a cross-sectional view showing an example of a twisted structure of the present invention. S1-S7・・・Composite strand patent applicant
Representative of Ube Nitto Kasei Co., Ltd.
Patent Attorney - Iro Ken Axial Patent Attorney Masatoshi Matsumoto 2591'/8 (,'/) Figure 3 (B) Figure 4

Claims (6)

[Claims] (1) Twisting made by twisting together a plurality of composite strands made by covering the outer periphery of an uncured filament with a thermoplastic resin in which a reinforcing fiber material is impregnated with an uncured thermosetting resin, and then curing the composite strands. The structure consists of a core strand arranged at the center and an outer peripheral strand twisted in the same direction at a predetermined twisting pitch around the outer periphery of the core strand, and the twisting pitch is set to the outer diameter of the uncured filament of the composite strand. A twisted structure made of fiber-reinforced thermosetting resin, characterized in that the fiber-reinforced thermosetting resin twist structure is 25 times or more. (2) Claim 1 characterized in that the outer periphery of the fiber-reinforced thermosetting resin twisted structure is coated with a thermoplastic resin.
The fiber-reinforced thermosetting resin twisted structure described above. (3) The required number of strands made of long reinforcing fibers are each impregnated with an uncured thermosetting resin, formed into a predetermined shape to form an uncured filament, and then melt-extruded. The outer periphery of each of the uncured filaments is annularly coated with a thermoplastic resin, and the coating layer is then immediately cooled to form a composite strand with an uncured interior. Subsequently, one of the composite strands is placed in the center as a core strand, and the remaining composite strands are twisted at a predetermined twisting pitch around the outer periphery of the core strand, hardened, and wound up. A method for manufacturing a curable resin twisted structure. (4) The fiber-reinforced thermosetting resin product according to claim 3, characterized in that in the twisting of the composite strands, the tension To of the outer strand is less than Tc with respect to the tension Tc of the core strand. Method for manufacturing twisted structures. (5) The fiber-reinforced thermosetting resin according to claim 3, wherein the composite strand is cured after being twisted at a temperature below the softening point of the thermoplastic resin coating layer of the composite strand. Method for manufacturing twisted structures. (6) The fiber-reinforced thermosetting resin twisted structure according to claim 3, wherein after the composite strands are twisted at a predetermined twisting pitch, the outer periphery of the composite strands is covered with a thermoplastic resin and then cured. How the body is manufactured.