JPH0716904A - Manufacture of fiber reinforced thermoplastic resin composite tube - Google Patents

Abstract

PURPOSE:To obtain a uniform sufficient fusion weld strength of a thermoplastic resin- coated layer by a method wherein an atmosphere near a contact interface between a resin-coated surface of a tubular material and extruded y' resin is made to be in a pressure-reduced state when thermoplastic resin is extrusion coated. CONSTITUTION:A sheet from which pressure is reduced is inserted into a U-shaped gap of a metal mold 29. The sheet is formed into a tubular material from the U-shape inside the metal mold 29. Molten resin 13 is extruded inside a formed fiber reinforced thermo-plastic resin tubular material 24 to be laminated inside that, which is introduced to a heating part. An interface between a fiber-reinforced layer and a resin layer is heated to a melting temperature or higher. Besides, an inside of the tube is pressurized from an air vent 31, which is pushed against the inner face of the metal mold. A two-layers tube which is integrated by fusion weld is introduced into a cooling metal mold 34 of a specific inner diameter provided via a thermal insulating material 33, stuck fast to each other, and cooled to at most a softening temperature of the resin to obtain a composite tube 25 wherein a thermoplastic resin-coated layer 22 is formed on the inner surface of the fiber reinforced thermoplastic resin tubular material 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber-reinforced thermoplastic resin composite pipe comprising a fiber-reinforced thermoplastic resin tubular body and a thermoplastic resin coating layer formed on the inner surface thereof.

[0002]

2. Description of the Related Art Generally, a fiber reinforced resin pipe (FRP pipe)
Is lighter than a metal pipe, does not rust, and has higher strength than a synthetic resin pipe, and is therefore widely used as a pipe member or a structural member.

In the conventional method for producing a fiber-reinforced resin pipe, continuous reinforcing fibers impregnated with a liquid thermosetting resin raw material composition are wound around a mandrel and heated in a heating furnace as it is to cure the resin composition. After the fiber-reinforced resin pipe was formed, the mandrel was extracted from the fiber-reinforced resin pipe by the so-called filament winding method.

[0004]

However, in such a conventional method for producing a fiber-reinforced resin pipe, there is a problem that it takes a long time to heat-harden the thermosetting resin compound, resulting in poor productivity. there were.

Therefore, in order to solve this problem, the present applicant has previously proposed a fiber-reinforced thermoplastic resin composite (fiber composite).
Has proposed a method for manufacturing a composite pipe in which a thermoplastic resin coating layer is provided on the inner surface and the outer surface of the tubular body of JP-A-3-15821.
(See No. 9). The method for producing a composite pipe according to this proposal is a step of continuously forming a tubular body from a sheet-shaped fiber composite in which a thermoplastic resin is held in continuous fibers arranged in the longitudinal direction, and while advancing the tubular body, A process in which a molten thermoplastic resin is laminated by extrusion along the inner surface and the outer surface to form a reinforcing layer in which reinforcing fibers are arranged in the axial direction and a coating layer made of the thermoplastic resin to form a laminated pipe. Met.

[0006]

However, in the method of manufacturing the composite pipe according to the above-mentioned proposal, when the molten thermoplastic resin is laminated on the inner surface and the outer surface of the tubular body by extrusion, the lamination interface, that is, the resin coating of the tubular body. Air is mixed in the surface and the contact interface between the extruded molten resin, and therefore the uniform and sufficient fusion bonding strength of the thermoplastic resin coating layer cannot be obtained,
Therefore, when hot water is circulated in the obtained composite pipe, or when the composite pipe is used at a high temperature, there is a problem that a portion where delamination or fusion strength is significantly deteriorated.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a tubular body when a molten thermoplastic resin is coated on the inner surface of a fiber-reinforced thermoplastic resin tubular body by extrusion. Air is not mixed in the contact surface between the resin-coated surface of the body and the extruded molten resin, and therefore a uniform and sufficient fusion-bonding strength of the thermoplastic resin-coated layer can be obtained, and for example, hot water is circulated in the composite pipe. It is an object of the present invention to provide a method for producing a fiber-reinforced thermoplastic resin composite pipe which does not cause delamination or deterioration in fusion strength even when the composite pipe is used at high temperature.

[0008]

In order to achieve the above object, a method for producing a fiber-reinforced thermoplastic resin composite pipe according to the present invention is to extrude a molten thermoplastic resin onto an inner surface of a fiber-reinforced thermoplastic resin tubular body. A method for producing a composite pipe in which a thermoplastic resin coating layer is continuously formed by coating with a resin coating surface of a tubular body and an extruded molten resin during extrusion coating of the molten thermoplastic resin. It is characterized in that the atmosphere near the contact interface is depressurized.

In the above description, the fiber-reinforced thermoplastic resin tubular body is formed by continuously shaping the sheet-shaped fiber composite in which continuous reinforcing fibers arranged in the longitudinal direction and the thermoplastic resin are integrated into a tubular shape. In some cases, a fiber-reinforced thermoplastic resin sheet composed of a continuous reinforcing fiber and a thermoplastic resin arranged in the longitudinal direction is continuously formed into a tubular shape to form a fiber-reinforced thermoplastic resin tubular body. And a method for producing a composite pipe in which the inner surface of the tubular body is coated by extrusion of a molten thermoplastic resin while advancing the tubular body to continuously form a thermoplastic resin coating layer, wherein During extrusion coating of the thermoplastic resin, the atmosphere in the vicinity of the contact interface between the resin coating surface of the tubular body and the extruded molten resin is depressurized.

The thermoplastic resin used in the method of the present invention is not particularly limited, and is a thermoplastic resin suitable for the purpose of use of the obtained composite pipe, and examples thereof include polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene,
Examples thereof include polystyrene, polyamide, polycarbonate, polyphenylene sulfide, polysulfone, and polyether ether ketone.

These thermoplastic resins may be used alone or as a mixture of a plurality of resins.
In addition, these thermoplastic resins include heat stabilizers, plasticizers, lubricants, antioxidants, ultraviolet absorbers, pigments, inorganic fillers, additives such as reinforcing fibers, fillers, processing aids, modifiers, etc. May be added.

Further, the resin used for the fiber-reinforced thermoplastic resin tubular body and the thermoplastic resin forming the thermoplastic resin coating layer on the inner surface of the tubular body are preferably the same, but the same. There is no particular need, and the two may be different from each other as long as the resin has a fusion property such that the fusion interface between the tubular body and the resin coating layer is not easily broken.

Further, the fibers used for the above-mentioned fiber-reinforced thermoplastic resin tubular body include roving-like or strand-like ones composed of continuous filaments having a diameter of 1 to several tens of μm. This fiber is a synthetic or natural organic fiber such as glass fiber, carbon fiber, metal fiber, aramid fiber, or vinylon, and all of the fibers that can be used as the reinforcing fiber of the thermoplastic resin are preferably used. .

In some cases, the fiber-reinforced thermoplastic resin tubular body may have a laminated structure of two or more layers, and the fibers used in each layer at that time may be the same type of fibers, or Different types of fibers may be used.

Further, the sheet-shaped fiber composite is preferably a composite in which the thermoplastic resin is sufficiently impregnated between the filaments and held, and such a continuous fiber is reinforced. It is preferable because it improves the watertightness of the pipe.

The width and thickness of the sheet-shaped fiber composite in claim 2 are not particularly limited, but the width is approximately equal to the outer peripheral length of the tubular body formed therefrom, and the thickness is usually 0.1 to 0.1. It is 3 mm. The amount of fibers in the sheet-shaped fiber composite is usually 5 to 70% by volume. If it is less than 5% by volume, a sufficient reinforcing effect cannot be obtained, and if it exceeds 70% by volume, the thermoplastic resin is not sufficiently impregnated and fusion bonding becomes difficult, and the reinforcing effect becomes small.

The sheet-like fiber composite may be one in which net-like reinforcing fibers are integrated inside, and a mat-like material in which short fibers are randomly oriented is fused and integrated by a thermoplastic resin film. It may be

To obtain a sheet-shaped fiber composite, for example, a thermoplastic resin is first adhered to and trapped between continuous fibers, and then the resin is heated and pressure-melted to impregnate the continuous fibers,
Although it is cooled and shaped, specifically, a roving-shaped or strand-shaped continuous fiber material composed of a large number of filaments is passed through (i) a fluidized bed of powdered thermoplastic resin, or (ii) ) Is it possible to impregnate the powdery thermoplastic resin between the filaments by passing through a bath of a liquid in which the powdery thermoplastic resin is dispersed, and then to heat it above the melting temperature to integrate the fiber and resin? Or, after impregnation and once drying, the fibers and the resin are integrated by heating above the melting temperature. Further, in the case of a resin having a low melt viscosity, the continuous fiber material can be impregnated by a method of immersing the continuous fiber material in a bath of the molten resin.

Further, in the above method for producing a composite pipe, when the molten thermoplastic resin is extrusion-coated, the atmosphere in the vicinity of the contact interface between the resin-coated surface of the tubular body and the extruded molten resin is depressurized. The preferred range of pressure is 700 to
750 mmHg, preferably 720-730 mmHg.

[0020]

In the above, when the thermoplastic resin composite reinforced with fibers is heated, the fibers stand out on the surface of the composite or the surface of the composite becomes uneven. When a thermoplastic resin is extruded and coated on the inner surface of such a composite, air is entrapped in the recess of the composite, the contact area of the interface becomes small, and the fusion property of the laminated interface becomes poor.

According to the method of the present invention, the inner surface or the outer surface of the fiber-reinforced thermoplastic resin tubular body is coated with the molten thermoplastic resin by extrusion to form a thermoplastic resin coating layer continuously, Since the atmosphere in the vicinity of the contact interface between the resin-coated surface of the body and the extruded molten resin is in a reduced pressure state, even if irregularities occur on the surface of the composite, extrusion lamination can be performed without air entrapment in the recesses of the composite. Further, the fusion of the lamination interface becomes uniform and stronger, and the thermoplastic resin coating layer can have uniform and sufficient fusion strength. Therefore, for example, when hot water is circulated in the composite pipe or when the composite pipe is used at a high temperature, delamination or deterioration in fusion strength does not occur.

The fiber-reinforced thermoplastic resin tubular body is formed by continuously shaping a sheet-shaped fiber composite in which continuous reinforcing fibers arranged in the longitudinal direction and a thermoplastic resin are integrated into a tubular shape. May be used. In this case,
While continuously advancing a tubular body shaped continuously from a fiber reinforced thermoplastic resin sheet composed of continuous reinforcing fibers and a thermoplastic resin arranged in the longitudinal direction, similarly hold a depressurized state on its inner surface or outer surface. Meanwhile, the molten thermoplastic resin may be coated by extrusion to form a thermoplastic resin coating layer continuously, and this also similarly prevents air from being mixed into the contact interface with the extruded molten resin, and the thermoplastic resin coating A uniform and sufficient fusion bonding strength of the layer can be obtained.

In the method for producing a fiber-reinforced thermoplastic resin composite pipe of the present invention, both the inner surface and the outer surface of the tubular body are
You may form a thermoplastic resin coating layer.

[0024]

Embodiments of the present invention will now be described with reference to the drawings.

Example 1 [Method for producing sheet-shaped fiber composite] The sheet-shaped fiber composite used in this example was produced as follows using the method (i).

For the thermoplastic resin, the following resin composition (A) is used.
It was used.

Resin composition (A) Chlorinated polyvinyl chloride resin (chlorination degree 67%, polymerization degree 1000, particle size about 80 μm) 100 parts by weight Tin-based heat stabilizer 4 parts by weight stearyl alcohol 2 parts by weight Polyethylene wax 0 0.5 parts by weight As shown in FIG. 1, ten glass fiber rovings (4400 tex) (1) as connecting reinforcing fibers composed of filaments having a diameter of 23 μm were arranged in a sheet shape in two layers, and the resin composition Air in which the powdery thermoplastic resin composition (2) comprising (A) is pressure-fed in the direction of the arrow.
After passing through the fluidized bed (4) fluidized by (3) to attach the composition (2) to the filaments of the glass fiber roving (1), the upper and lower glass fiber roving (1) ) A pair of heating rolls, which are heated to approximately 220 ° C, with a net-shaped glass fiber material (6) sandwiched between (1)
The composition (2) was melted and impregnated by heating and pressurizing with (5) to obtain a sheet-shaped glass fiber composite (7). Here, the weight ratio of the resin to the glass fiber of the glass fiber composite (7) was resin: glass fiber = 70: 30.

[Manufacturing Method of Fiber Reinforced Thermoplastic Resin Tubular Body] Next, an apparatus used for carrying out the present invention will be described.
A description will be given with reference to the drawings. In the following description, the term “front” means the right direction in FIG. 2.

The apparatus for producing a fiber composite tube shown in FIG. 2 has a sheet-like fiber composite (7) (width = 90 mm, thickness = 0.5 m).
m) is wound around the rewinding roll (26), the inner layer thermoplastic resin extruding machine (28), and as shown in FIG. 3 to FIG. The outer mold (29) and the inner mold (29 '), which can be formed into a circular shape, are attached to the rear of the mold, which is bent to the front and has a circular slit part in front of it. Vacuum mold (9)
And a vacuum pump (10) connected to the depressurization mold.

A U-shaped gap (8a) is formed as shown in FIG.
A rubber plate for sealing (8) provided with is fixed to the rear part of the pressure reducing mold (9) with bolts (11) and the like. Furthermore, the mold (29)
It is fixed to the rear end of the
1) A tube-shaped inner core (30) and an air pressure generator (32) for pressurizing the inside of the composite pipe through the vent hole (31) are arranged. Furthermore, the heat insulating material (33) provided in front of the mold, the cooling mold (34), the wire (20) attached to the tip of the inner core (30), and the tip of the wire (20), A seal plate (21) capable of sealing the air inside the pipe, and a take-up machine (23) arranged in front of it (illustrated in FIG. 11)
It is equipped with and.

A U-shaped gap (9a) into which the sheet-shaped fiber composite (7) can be inserted is provided behind the mold (29) and behind the decompression mold (9). Fiber composite
(7) is inserted and while the seat is in U-shape in the decompression die (9), the decompression pump (10) is installed inside and outside the seat in the decompression die.
Is used to reduce the pressure to 720 mmHg.

The depressurized sheet is inserted into the U-shaped gap of the mold (29) while maintaining the depressurized state, and inside the mold (29), the sheet is deformed from the U-shape to an outer diameter of 28.8 mm and a thickness of 0. 5 mm
Of the fiber-reinforced thermoplastic resin tubular body (24) formed by continuously shaping into a tubular body of, and chlorinated polyvinyl chloride resin (average degree of polymerization = 1000) (13) extruded and laminated inside Then, it is introduced into a heating section maintained at 220 ° C. by a heating device (35) to heat at least the interface between the fiber reinforced layer and the resin layer to a melting temperature or higher, and at the same time, the inside of the tube is vented to the inner core
From (31), a pressure of 0.5 kg / cm ² is applied and pressed against the inner surface of the mold to fuse and integrate the reinforcing layers. The fusion-integrated two-layer pipe is introduced into a cooling mold (34) having a constant inner diameter provided through a heat insulating material (33) and brought into close contact with it, cooled to a temperature not higher than the softening temperature of the resin, and fiber-reinforced thermoplastic A fiber reinforced thermoplastic resin composite pipe (25) having an outer diameter of 28.8 and a thickness of 1.5 mm, in which the thermoplastic resin coating layer (22) was formed on the inner surface of the resin tubular body (24), was obtained. The above-mentioned series of steps was continuously carried out by the take-up machine (23) to continuously form the composite pipe (25).

Example 2 Only the following points are different from Example 1, and the other steps are the same as those of Example 1, and two fiber reinforced resin layers (26 ') and (27') as shown in FIG. 9 are obtained. ), A fibrous thermoplastic resin composite tube having an inner diameter of 50 mm and an outer diameter of 54 mm was manufactured.

(I) A polypropylene resin (MI = 0.5) was used as the thermoplastic resin for the inner layer extrusion.

(II) A polypropylene resin (MI = 0.5, average particle size = 200 μm) was used as the powdery thermoplastic resin for the sheet-shaped fiber composite. Of the devices shown in FIG.
A sheet-like glass fiber composite (27) (thickness: 0.4 mm) was prepared by using the upper fluidized bed (4) only and by the same molding method as in Example 1 (however, the glass net (6) was not inserted). ) Got. This glass fiber composite (27) has a length of 5
An upper and lower endless belt together with a sheet (thickness = 0.3 mm) made of polypropylene resin (MI = 0.5) above and below a glass mat (needling treated) having a thickness of about 2 mm, which is composed of a filament of 0 mm and a diameter of 7 to 13 µm.
(38) Pulled into (39), after heating the resin to the melting temperature in the heating furnace (40), pressed by the press roll (41), cooled,
A sheet-shaped fiber composite reinforcing body (37) was obtained. The weight ratio of the resin to the glass fiber was resin: glass fiber = 60: 40.

(III) Both ends of this sheet-shaped fiber composite reinforcement were trimmed to obtain a sheet-shaped fiber composite reinforcement having a width of 151 mm and a thickness of 1.5 mm.

(IV) The sheet-shaped fiber composite reinforcement formed in the steps (IV) and (3) is shaped into a tube, and the tubular body has an outer diameter of 52 m.
m. At this time, the sheet-shaped fiber composite (27) was placed so that the surface on which the sheet-shaped fiber composite (27) was placed was on the outside.

(V) 1.0 from the vent hole (31) of the inner core (30)
Pressurization was performed at a pressure of kg / cm ² .

Comparative Example 1 A fiber reinforced thermoplastic resin composite pipe was obtained by molding in the same manner as in Example 1 except that the pressure reducing step was not performed.

Comparative Example 2 A fiber-reinforced thermoplastic resin composite pipe was obtained by molding in the same manner as in Example 2 except that the pressure reducing step was not performed.

The cross sections of the composite pipes molded according to the examples and comparative examples were observed with a microscope. Further, each of the composite pipes was cut into a length of 2 cm in a lengthwise direction, and the shear punching strength at the laminated interface was measured. The observation results and shear strength are shown below.

[0042]

[Table 1] Many voids having a size of about 100 μm were observed at the interface between the reinforcing layer and the resin layer of the composite pipe not subjected to the depressurization step, whereas almost no void was observed at the interface in the composite tube subjected to the depressurization step. .

Further, the shear punching strength of the composite pipe not subjected to the depressurizing step is weak and has a large variation, whereas the composite pipe according to the present invention is a composite pipe excellent in fusion strength and uniformity of fusion. .

Example 3 A resin coating mold (42) shown in FIG. 10 was placed in front of a mold of the same type as the mold for producing a composite pipe used in Example 1, and the method of Example 1 was used in advance. The created two-layer tube was inserted into the mold from the rear, and the decompression zone formed by the inner surface of the mold, the two-layer tube and the rubber plate (8 ') was evacuated to 730 mmHg by the vacuum pump (10'). , Extruded and coated with a molten polyvinyl chloride resin (PVC resin) having the following composition at 205 ° C. from the die tip, and using a sizing die, outer diameter 32 mm, wall thickness 2.1 m
m fiber reinforced thermoplastic resin composite tube was obtained.

Resin composition for outer layer Polyvinyl chloride resin (degree of polymerization: 700) 100 parts by weight Tin-based heat stabilizer 3 parts by weight Stearyl alcohol 1 part by weight Polyethylene wax 0.5 parts by weight In the tube, no void was observed at the interface between the tubular body and the outer resin coating layer. The shear strength of the composite pipe of this example is 800 ± 3.
It was 0 kgf / cm.

[0046]

EFFECTS OF THE INVENTION Generally, when a fiber-reinforced thermoplastic resin composite is heated, fibers stand out on the surface of the composite or irregularities are formed on the surface of the composite. When a thermoplastic resin is extruded and coated on the inner surface of such a composite, air is entrapped in the recess of the composite, the contact area of the interface becomes small, and the fusion property of the laminated interface becomes poor.

According to the method of the present invention, when the inner surface of the fiber-reinforced thermoplastic resin tubular body is coated with the molten thermoplastic resin by extrusion to form the thermoplastic resin coating layer continuously, Since the atmosphere in the vicinity of the contact interface between the resin-coated surface and the extruded molten resin is in a reduced pressure state, even if irregularities occur on the composite surface, extrusion lamination can be performed without air entrapment in the composite recesses. The fusion at the interface becomes uniform and stronger, and uniform and sufficient fusion bonding strength of the thermoplastic resin coating layer can be obtained. Therefore, for example, when hot water is circulated in the composite pipe or when the composite pipe is used at a high temperature, delamination or deterioration in fusion strength does not occur.

The fiber-reinforced thermoplastic resin tubular body is formed by continuously shaping a sheet-shaped fiber composite in which continuous reinforcing fibers arranged in the longitudinal direction and a thermoplastic resin are integrated into a tubular shape. May be used, in this case,
While advancing the continuously shaped tubular body from the fiber reinforced thermoplastic resin sheet consisting of continuous reinforcing fibers and thermoplastic resin arranged in the longitudinal direction, on the inner surface of this, while also maintaining a reduced pressure state, The molten thermoplastic resin may be coated by extrusion to form a thermoplastic resin coating layer continuously,
This also brings about an effect that air is not mixed in the contact interface with the extruded molten resin and uniform and sufficient fusion bonding strength of the thermoplastic resin coating layer can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a process for producing a sheet-shaped fiber composite used for producing a composite pipe.

FIG. 2 is an explanatory diagram showing an example of steps of the method for manufacturing the composite pipe according to the first embodiment of the present invention.

FIG. 3 is an explanatory view showing a process of molding the tubular body of the first embodiment.

FIG. 4 is an enlarged sectional view taken along line IV-IV in FIG.

5 is an enlarged cross-sectional view taken along the line VV of FIG.

FIG. 6 is an enlarged rear view of the mold for manufacturing the composite pipe of FIG.

7 is an enlarged cross-sectional view taken along the line VII-VII in FIG.

8 is an enlarged cross-sectional view showing a modified example of the mold for manufacturing the composite pipe of FIG.

FIG. 9 is a partially cutaway enlarged perspective view of a composite pipe made by the manufacturing method of the second embodiment.

FIG. 10 is an explanatory diagram showing a step of producing a fiber composite used for producing the composite tube of the second embodiment.

FIG. 11 is an explanatory diagram showing an example of steps of a method for manufacturing a composite pipe according to the third embodiment of the present invention.

[Explanation of symbols]

 7,27 Sheet-shaped fiber composite 9 Reduced pressure mold 10 Vacuum pump 13 Extruded molten resin 22 Thermoplastic resin coating layer 24 Fiber-reinforced thermoplastic resin tubular body 25 Fiber-reinforced thermoplastic resin composite pipe 29 Outer mold 29 'Inner mold

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29L 23:22

Claims (2)

[Claims] 1. An inner surface of a fiber-reinforced thermoplastic resin tubular body,
A method for producing a composite pipe by coating a molten thermoplastic resin by extrusion to continuously form a thermoplastic resin coating layer, wherein the extrusion coating of the molten thermoplastic resin, at the time of resin coating surface of the tubular body and A method for producing a fiber-reinforced thermoplastic resin composite pipe, characterized in that the atmosphere in the vicinity of the contact interface with the extruded molten resin is depressurized. 2. A fiber-reinforced thermoplastic resin tubular body is formed by continuously shaping a sheet-shaped fiber composite in which continuous reinforcing fibers arranged in a longitudinal direction and a thermoplastic resin are integrated into a tubular shape. A method for producing a composite pipe in which the inner surface of the tubular body is coated with the molten thermoplastic resin by extrusion while advancing the tubular body to continuously form a thermoplastic resin coating layer, wherein the molten thermoplastic resin is A method for producing a fiber-reinforced thermoplastic resin composite pipe, characterized in that, during the extrusion coating, the atmosphere in the vicinity of the contact interface between the resin-coated surface of the tubular body and the extruded molten resin is depressurized.