JPH0798350B2 - Method for manufacturing fiber-reinforced synthetic resin pipe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a fiber-reinforced synthetic resin pipe.

[Prior Art] A thermoplastic resin tube has excellent characteristics such as being lighter in weight and not rusting as compared with a metal tube, and is widely used today. On the other hand, however, they are inferior in pressure resistance and impact resistance to metal pipes. Therefore, as an improvement of these drawbacks of the thermoplastic resin tube, a fiber-reinforced synthetic resin tube having a two-layer structure in which a fiber-reinforced thermosetting resin layer is provided on the outer circumference of an inner layer tube made of a thermoplastic resin is used. It became so. Further, in Japanese Examined Patent Publication No. 62-773, as described above, the outer side of the inner layer pipe made of a thermoplastic resin is reinforced with a fiber-reinforced thermosetting resin layer, and the outer periphery thereof is extrusion-coated with a thermoplastic resin. A method for manufacturing a composite pipe having an outer layer formed into a three-layer structure, and Japanese Patent Laid-Open No. 57-10030 discloses that a thermoplastic resin is used as a resin of a fiber reinforced resin layer for reinforcing an inner pipe, and A fiber-reinforced thermoplastic resin tube having a three-layer structure in which an outer layer is formed by extrusion-coating a thermoplastic resin on the outer periphery and a method for producing the same has been proposed.

[Problems to be Solved by the Invention]

However, in these conventional fiber-reinforced composite pipes having a three-layer structure, although the fiber-reinforced resin layer is extrusion-coated with a thermoplastic resin, the fiber-reinforced resin layer formed by a method of winding the fiber composite or the like. The unevenness of the outer layer is likely to appear on the outer layer surface, the outer diameter accuracy of the outer layer is inferior, and when connecting pipes or pipes and joints, the joint will be incomplete and fluid leakage will occur, so to prevent this It requires flattening by means such as cutting the irregularities of the pipe.

The present invention has been made in view of the above problems, and an object thereof is a fiber having good outer diameter accuracy, which does not require processing such as cutting the pipe when joining the pipes. It is intended to provide a method for manufacturing a reinforced synthetic resin pipe.

[Means for Solving the Problems]

In order to achieve the above object, the method for producing a fiber-reinforced synthetic resin pipe of the present invention, a fiber-reinforced thermoplastic resin layer is provided on the outer periphery of the thermoplastic resin inner layer pipe, the fiber-reinforced thermoplastic resin layer A tubular body in which a thermoplastic resin is fused to the thermoplastic resin of the inner-layer pipe is continuously transferred in one direction, and the outer periphery of the fiber-reinforced thermoplastic resin layer is extrusion-coated with a foamable thermoplastic resin. , Then, during the foaming of the expandable thermoplastic resin, by cooling sizing to an outer diameter dimension less than the outer diameter of the pipe obtained when the expandable thermoplastic resin is completely foamed,
The gist is to form an outer layer fused to the fiber-reinforced thermoplastic resin layer.

The inner layer tube in the present invention is formed by heating and kneading a thermoplastic resin by a screw type extruder and passing it through a mold attached to the tip of the extruder. The thermoplastic resin used for the inner layer pipe is not particularly limited as long as it can be extruded into a tubular shape, and depending on the purpose of use of the pipe, polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene,
Polystyrene, polyamide, polycarbonate, polyphenylene sulfide, polysulfone, polyether ether ketone, polyvinylidene fluoride and the like are used. These resins may be used alone or as a mixture of two or more. Further, additives such as a heat stabilizer, a lubricant, a plasticizer, a pigment, a filler, a processing aid and a modifier may be added depending on the purpose.

In the present invention, the fiber-reinforced thermoplastic resin layer provided on the outer periphery of the inner layer tube is roving-shaped, mat-shaped, cloth-shaped glass fiber, carbon fiber, inorganic fiber such as metal fiber, or aramid fiber, organic vinylon fiber A reinforcing fiber made of a synthetic fiber impregnated with the thermoplastic resin used for the inner layer tube is wound around the outer layer of the inner layer tube and cured to form it.

The resin to be impregnated does not necessarily have to be the same as the resin of the inner layer pipe, but in order to obtain a high-strength fiber-reinforced composite pipe, it has good adhesiveness to the inner layer pipe and good compatibility with the resin of the inner layer pipe. Those are preferable.

In the production method of the present invention, the steps up to the formation of the inner layer tube and the formation of the fiber reinforced thermoplastic resin layer provided on the outer periphery thereof are the subsequent step of covering the foamable thermoplastic resin, the foaming step, and the sizing step. May be separated, or may be a series of continuous steps as described later.

In the present invention, the expandable thermoplastic resin extruded on the outer periphery of the fiber-reinforced thermoplastic resin layer is the same resin as that used for the inner layer tube, but is not necessarily limited to the same resin. .

In order to impart foamability to the thermoplastic resin of the outer layer formed on the outer periphery of the fiber reinforced thermoplastic resin layer, it decomposes at the extrusion molding temperature to generate a gas containing N ₂ , CO, CO ₂ etc. as the main components. A decomposing type foaming agent to be mixed with the thermoplastic resin for the outer layer in a necessary amount to form a foamable thermoplastic resin, and this is extruded,
Used to extrude a foamable thermoplastic resin that has been previously impregnated with a volatile liquid at the extrusion molding temperature, or to extrude the volatile liquid into the molten resin from the middle of the extruder during extrusion. Although a method suitable for the thermoplastic resin is adopted, the method can be easily applied to various thermoplastic resins, and a thermoplastic resin material for molding containing a commercially available decomposition type foaming agent is preferably used. Further, these thermoplastic resins may be subjected to modification such as cross-linking which is usually performed to improve foamability.

Examples of the decomposition-type foaming agent used in the above method include azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, p, p'-oxybis (benzenesulfonylhydrazide), 5- Phenyl-tetrazole and the like can be used. The volatile liquid used in the method, for example, isopentane, heptane, aliphatic hydrocarbons such as cyclohexane, trichlorotrifluoroethane,
Fluorinated aliphatic hydrocarbons such as dichlorotetrafluoroethane can be used.

The expansion ratio of the expandable thermoplastic resin is not particularly limited,
For the purpose of improving the outer diameter accuracy of the fiber reinforced synthetic resin pipe in the present invention, it is not particularly necessary to have a high magnification, and from the viewpoint of preventing the joint strength with the joint from being extremely reduced,
It is preferable that the expansion ratio is about 1.2 to 5 times. The thickness of the expandable thermoplastic resin layer is preferably about 0.5 to 5 mm.
If it is less than 0.5 mm, the effect of improving the outer diameter accuracy is not sufficient, and if it exceeds 5 mm, the material is wasted and the connection strength may be slightly reduced.

As described above, in the present invention, the type and combination of the resin used for the inner layer pipe, the fiber reinforced thermoplastic resin layer, and the outer layer are not particularly limited, but the resin of the fiber reinforced thermoplastic resin layer is used for the inner layer pipe. Each of the layers is a thermoplastic resin that has a good affinity with and can be fusion-bonded to the resin, and the resin of the outer layer is a thermoplastic resin that has a good affinity with the resin of the fiber-reinforced thermoplastic resin layer and that can be fused. It is preferable that the resin is in a fused state in that a fiber-reinforced synthetic resin tube excellent in strength and durability can be obtained. As a preferable example of a specific combination of such resins, an inner layer tube, a fiber-reinforced thermoplastic resin layer, an outer layer composed of the same kind of thermoplastic resin, an inner layer tube is chlorinated polyvinyl chloride, fiber A combination of resins of the same series such as a vinyl acetate-vinyl chloride copolymer for the reinforced thermoplastic resin layer and polyvinyl chloride for the outer layer is adopted.

The manufacturing method of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a schematic explanatory view showing an example of a manufacturing apparatus for manufacturing the fiber-reinforced synthetic resin pipe of the present invention.

Reference numeral 1 is an extruder for melt-kneading a thermoplastic resin and extruding it.
A mold 2 for molding the molten thermoplastic resin extruded from the extruder 1 into a hollow tubular inner layer pipe 3 is attached to the tip of the extruder 1, and an inner layer extruded from the mold 2 is provided in front of the mold 2. Tube 3
There are provided two sets of winding devices 5, 5 that rotate around the inner layer tube 3 and wind the tape-shaped fiber composite 4 for forming the fiber reinforced thermoplastic resin layer on the outer periphery of the inner layer tube 3. Each winding device
A bobbin-shaped unwinder 5 in which the fiber composite 4 is wound around the 5, 5
Two a and 5a are attached to each unwinder, which are rotated around the inner layer tube 3 by a driving device (not shown).
The tape-shaped fiber composite body 4 is unwound from 5a, 5a and is wound around the outer circumference of the inner layer tube 3 in a helical shape. The two winding devices 5, 5 are configured to rotate in opposite directions. Hot air type heating devices 6, 6 are provided near the front of each winding device 5 to heat the fiber composite 4 wound around the outer circumference of the inner layer tube 3. Further, in front of the inner layer tube 3, there are two fiber composites 4 on the outer circumference.
An extruder 7 in which a crosshead mold 8 for extrusion-coating a foamable thermoplastic resin is attached to the outer periphery of a tubular body 11 wound into a layer and formed with a fiber-reinforced thermoplastic resin layer,
A cooling device 9 such as a water tank provided with a die for outer diameter sizing, and a take-up machine 10 are installed near the front of the crosshead die 8. As the outer diameter sizing die, a cylinder having an inner diameter smaller than the outer diameter obtained when the expandable thermoplastic resin is completely foamed, or a plurality of rings is preferably used.

Next, a method for manufacturing the fiber-reinforced synthetic resin pipe of the present invention using the above apparatus will be described.

A thermoplastic resin to which a heat stabilizer, a lubricant, and other necessary additives are added is melt-kneaded in an extruder 1 and passed through a mold 2 to extrude an inner layer tube 3.

Then, the tape-shaped fiber composite 4 is unwound from the unwinders 5a, 5a of the first winding device 5 around the outer circumference of the inner layer tube 3 extruded from the mold 2 to form gaps and overlaps. Is helically wound so as not to generate, and hot air is blown from the periphery of the fiber composite 4 by the hot air type heating device 6 to heat and melt the resin in the fiber composite 4 and fuse it with the inner layer tube 3, The fiber-reinforced thermoplastic resin layer of the first layer is formed. Then, by the second winding device 5, the second fiber-reinforced thermoplastic resin layer is helically wound in the opposite direction to the first layer, and similarly two fiber-reinforced thermoplastic resin layers are formed. The formed tubular body 11 is molded. Thus, in forming the fiber-reinforced thermoplastic resin layer of the first layer and the second layer, by winding the fiber composite 4, 4 in the opposite direction, compared to the case of winding in the same direction. , Even if stress is applied to the pipe, fiber displacement is unlikely to occur,
An excellent reinforcing effect can be exhibited.

As a method of winding the fiber composite around the inner layer tube, fusing, and forming the fiber-reinforced thermoplastic resin layer, the method of winding in the circumferential direction is simple and rational, but the strength in the tube axis direction, When dimensional accuracy is required, the fiber composite may be fused in a state of being surrounded along the pipe axis direction.

In order to prevent the inner layer tube 3 from being deformed when the fiber composite 4 is wound around and fused to the outer circumference of the inner layer tube 3, the mold 2 is used.
Is provided with an extension core protruding in the extruding direction, and the fiber composite body 4 is wound on the extension core, or cooling air is blown into the inner layer tube 3 from the tip of the mold 2 to form the inner layer tube 3
You may take measures against deformation, such as winding the fiber composite 4 while cooling the inner surface of the.

Subsequently, the tubular body 11 is guided to the crosshead mold 8 attached to the extruder 7, and the outer periphery of the tubular body 11 is coated with the foamable thermoplastic resin kneaded by heating by the extruder 7 to form a crosshead mold. Immediately after passing through 8, the foamable thermoplastic resin is passed through a water-cooled outer diameter sizing die installed in the water tank 9 at the stage of complete foaming to obtain the outside of the tube obtained when completely foamed. The outer diameter is forcibly restricted to less than the outer diameter, cooled sufficiently with water, and the dimensions are fixed.
And the fiber-reinforced composite tube 12 is obtained.

FIG. 2 is a schematic explanatory view showing another example of the manufacturing apparatus for manufacturing the fiber reinforced synthetic resin pipe of the present invention. The first
The method for manufacturing the fiber-reinforced synthetic resin pipe shown in the figure uses a tape-shaped fiber composite, while the manufacturing method in FIG. 2 uses a strand-shaped fiber composite such as roving or yarn. .

In FIG. 2, equipment common to FIG. 1 is given the same reference numeral, and description thereof will be omitted.

In FIG. 2, 14 is an unwinding device that feeds the roving-shaped fiber composite 13 in the axial direction of the peripheral tube of the inner layer tube 3, and a plurality of bobbin-shaped windings around which the fiber composite 13 is wound. Start
14a, 14a ... are attached, and the fiber composite 13
Are supplied onto the inner layer tube 3 extruded from the mold. The numeral 15 is installed immediately after the unwinding device 14 and has a drum-shaped heating roll for heating the fiber composite 13, and 16 is the inner tube 3 for the fiber composite 13
It is a winding device that winds around the circumference of
Similarly, a plurality of bobbin-shaped unwinders 16a, 16a ... On which the fiber composite 13 is wound are attached, and the unwinding device rotates the periphery of the inner layer tube 3 to drive each unwinder 16a, 16a. The fiber composite 13 is unwound from 16a ... and wound around the inner layer tube 3.

A method for manufacturing the fiber-reinforced synthetic resin pipe of the present invention using the apparatus shown in FIG. 2 will be described.

The roving-shaped fiber composite material 13 unwound from the unwinding device 14 is fed in the axial direction of the peripheral tube of the inner layer tube 3 extruded in the same manner as in FIG. The fiber composite 13, the inner layer tube 3, and the outer surface are heated and fused. Next, the fiber composite material 13 is unwound from the winding device 16, and the fiber composite material 13 is circumferentially wound on the inner layer tube 3 reinforced in the tube axis direction, and the fiber composite material 13 is heated by the hot air heating device 6. body
13 is heated and melted to obtain a tubular body 17. Further, as in the case of FIG. 1, an outer layer of a foamable thermoplastic resin is formed on the outer periphery of the tubular body 17 to obtain a fiber reinforced synthetic resin pipe 18.

As a method of fusing the wound fiber composite to the inner layer tube,
The fiber composite may be quickly wound and fused on the hot inner layer tube immediately after being extruded from the mold, or the inner layer tube may be cooled once and its outer surface and the fiber composite may be simultaneously or separately separated. Alternatively, the fiber composite may be wound and fused around the inner layer tube after being heated with hot air or an infrared heater to such an extent that the resin is melted. The heating of the inner layer pipe is preferably carried out rapidly in a short time so that only the outer surface of the inner layer pipe is melted and the inside of the pipe meat is not melted.

In addition, FIG. 1 is an example in which two layers of the fiber-reinforced thermoplastic resin layer in the circumferential direction by the fiber composite 4 and two layers of the outer layer of the expandable thermoplastic resin are further provided thereon, and FIG. Fiber composite 14
According to the example, there is one fiber-reinforced thermoplastic resin layer in the tube axis direction, one circumferential fiber-reinforced thermoplastic resin layer, and one outer layer of expandable resin on top of that. The number is not particularly limited to these, and can be appropriately determined according to the application, required strength, and the like.

In the method for manufacturing the fiber-reinforced synthetic resin pipe, a method for manufacturing a fiber-reinforced synthetic resin pipe by impregnating resin between filaments in a separate line and using the fiber composite wound on a bobbin-shaped unwinder Although described, the manufacturing method may further include continuously winding or unwinding around the inner layer tube while forming the fiber composite, and fusing to form the reinforcing layer.

[Action]

A fiber reinforced thermoplastic resin layer is provided by a method such as winding a fiber composite around the outer circumference of a thermoplastic resin inner layer tube, and the thermoplastic resin of the fiber reinforced thermoplastic resin layer is the thermoplastic resin of the inner layer tube. Since it is fused, the bond between the inner layer tube and the fiber-reinforced thermoplastic resin layer becomes strong, and the expandable thermoplastic resin extruded and coated on the outer periphery of the tubular body is then passed through the outer diameter sizing die. In addition, while the outer diameter is regulated to the outer diameter dimension of the foamable thermoplastic resin which is not completely foamed and is sized, and the defective portion such as the recessed portion of the fiber reinforced thermoplastic resin layer is filled. It is foamed, solidified by cooling, and fused to the fiber-reinforced thermoplastic resin layer to form an outer layer.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. (See Fig. 1) In extruder 1, melt-knead polyvinyl chloride resin (heat distortion temperature 72 ℃) mixed with heat stabilizer, lubricant, etc.
The inner layer pipe 3 having an inner diameter of 25 mm and a wall thickness of about 2 mm is extruded by the die 2 of FIG. The inner layer tube 3 thus formed is helically wound and fused by the winding device 5 while being heated by the hot-air type heating device 6 so that the outer surface temperature thereof does not decrease. Then, in the same manner, the fiber composite body 4 of the second layer was helically wound in the direction opposite to the direction of the first layer and fused to form the tubular body 11.

The fiber composite 4 used was a tape having a thickness of about 0.5 mm and a width of about 20 mm. After the roving of glass fiber was opened, a vinyl acetate-polyvinyl chloride copolymer (vinyl acetate content of 10 %, The heat distortion temperature of 64 ° C) was well impregnated and molded. The glass fiber amount in the fiber composite 4 is 30.
It was% by volume.

Then, the tubular body 11 (outer diameter of about 31 mm) is introduced into a crosshead mold 8 for coating an outer layer, and a commercially available foamable polyvinyl chloride resin (manufactured by Shin-Etsu Chemical Co., Ltd. RF-
103S set foaming ratio: about 2 times), and the barrel temperature of the extruder
Extrusion was performed under the conditions of 150 to 175 ° C. and the temperature of the crosshead mold 8 of about 175 ° C., and the outer surface of the fiber-reinforced thermoplastic resin layer was extrusion-coated to a thickness of 1 mm in a non-foamed state. The coated expandable polyvinyl chloride resin started foaming at the point of exiting the crosshead mold 8 and was completely foamed, and as a result, a fiber-reinforced synthetic resin tube having a minimum outer diameter of about 35 mm was obtained. Since this fiber-reinforced synthetic resin tube was naturally foamed without restricting the outer diameter, the outer diameters were not the same and irregularities of the fiber-reinforced thermoplastic resin layer appeared on the outer layer surface.

Next, a water cooling type sizing die having a cylindrical sizing hole whose inner diameter is slightly larger than 34 mm is installed with a cooling device 9 so that the outlet of the crosshead die 8 is located at a position of about 200 mm. The tubular body coated with the expandable polyvinyl chloride resin was passed through a sizing die and completely cooled in a cooling water tank to obtain a fiber-reinforced synthetic resin pipe 12 having an outer diameter of 34 mm.

The fiber-reinforced synthetic resin pipe obtained as described above does not show irregularities of the fiber-reinforced thermoplastic resin layer on the outer layer surface, has excellent dimensional accuracy, and the inner layer pipe and the fiber-reinforced thermoplastic resin layer, and the outer layer. They were firmly fused to each other.

〔The invention's effect〕

The method for producing a fiber-reinforced synthetic resin pipe of the present invention comprises a fiber-reinforced thermoplastic resin layer on the outer periphery of a thermoplastic resin inner layer pipe, wherein the thermoplastic resin of the fiber-reinforced thermoplastic resin layer is the heat of the inner layer pipe. As it is fused to the plastic resin, the bond between the inner layer tube and the fiber reinforced thermoplastic resin layer is strengthened, a fiber reinforced synthetic resin tube with high strength is obtained, and foam is formed on the outer periphery of the fiber reinforced thermoplastic resin layer. -Extruded coating of water-soluble thermoplastic resin and cooling sizing to an outer diameter smaller than the outer diameter of the tube obtained by spontaneous foaming of the expandable thermoplastic resin to form an outer layer fused to the fiber-reinforced thermoplastic resin layer. Therefore, it has a high peel strength,
The irregularities of the fiber reinforced thermoplastic resin layer are hidden, and a fiber reinforced synthetic resin tube with a smooth surface and high outer diameter accuracy is obtained.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an apparatus for manufacturing a fiber reinforced synthetic resin pipe of the present invention, and FIG. 2 is a schematic explanatory view showing another example of an apparatus for manufacturing a fiber reinforced synthetic resin tube of the present invention. 1,7 ... Extruder, 2 ... Mold, 3 ... Inner layer tube, 4,13 ... Fiber composite, 5,16 ... Rolling device, 6 ... Hot air type heating device, 8 ... Cross Head mold, 9 ... Cooling device, 10 ... Take-up machine, 11,17 ... Tubular body, 12,18 ... Fiber reinforced synthetic resin pipe, 14 ... Unwinding device, 15 ... Heating roll.

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Claims (1)

[Claims] 1. A thermoplastic resin inner layer tube is provided with a fiber reinforced thermoplastic resin layer on the outer periphery thereof, and the thermoplastic resin of the fiber reinforced thermoplastic resin layer is fused to the thermoplastic resin of the internal layer tube. While the tubular body is continuously transferred in one direction, the outer periphery of the fiber-reinforced thermoplastic resin layer is extrusion-coated with an expandable thermoplastic resin layer, and then the foamable thermoplastic resin is expanded in the course of foaming. A fiber-reinforced synthetic material characterized by forming an outer layer fused to the fiber-reinforced thermoplastic resin layer by cooling-sizing to an outer diameter dimension smaller than the outer diameter of the pipe obtained when the thermoplastic resin is completely foamed. Method of manufacturing resin pipe.