JP2017007289A - Pipe molding and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile-like molded article which has high productivity, is light-weight and is excellent in specific strength and specific rigidity.SOLUTION: There is provided a piping molding having a two-layer structure of an outer cylindrical portion and an inside cylindrical portion, where the outer cylindrical portion is formed of a thermoplastic resin containing a textile of a continuous fiber for reinforcement, and the inside cylindrical portion is formed of a thermoplastic resin injection-molded to the inside of the outer cylindrical portion. The outer cylindrical portion is preferably formed of a textile formed of a prepreg tape formed by impregnating roving of the continuous fiber for reinforcement with a thermoplastic resin. The textile is a fabric, a knitted fabric or a braid of the prepreg tape, and an intersection portion of the prepreg tapes are preferably fused and bonded to each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pipe molded article having high rigidity and strength against compressive deformation and bending deformation, and suitable for a pipe-like structural material, a joint, and the like, and a manufacturing method thereof. In particular, the present invention is formed by an outer cylindrical portion formed of a thermoplastic resin containing a reinforcing continuous fiber textile, and an injection molded thermoplastic resin inside the outer cylindrical portion. The present invention relates to a pipe molded product comprising an inner cylindrical portion and a method for manufacturing the same.

  In general, a pipe-shaped resin molded product is manufactured by extrusion molding as disclosed in Patent Document 1. However, in order to obtain a pipe molded product having very high strength and rigidity, reinforcement with continuous fibers or the like is required. However, in extrusion molding, a suitable method for reinforcing with continuous fibers has not been proposed.

  On the other hand, Patent Document 2 discloses a method for producing a hollow body of a thermosetting resin reinforced with continuous fibers by a drawing method. However, when a thermosetting resin is used, the molding time is long, the productivity is low, and the impact resistance is low, so that it is unsuitable for application to automobile parts and industrial machines. In addition, the drawing method has been widely tested for thermoplastic resins, but the melt viscosity is high, impregnation into fibers is difficult, and application is difficult.

  Further, as disclosed in Patent Document 3, the fiber-reinforced resin pipe molded product is obtained by attaching the roving fiber impregnated with resin to a predetermined thickness while rotating a mandrel as a mold at a predetermined angle. Further, it is molded by a filament winding method in which an impregnated thermosetting resin is cured by heating. The filament winding method requires a curing reaction of the impregnated thermosetting resin, takes a long time for molding, and is difficult to apply to parts that require mass production such as automobile parts. In addition to filament winding, molded products can be obtained by centrifugal force molding, but there is still a big problem in mass production.

  In recent years, as disclosed in Patent Document 4 and Patent Document 5, a method has been proposed in which a prepreg reinforcing fiber impregnated with a thermoplastic resin in a roving is wound around a mandrel while being heated and melted, and then cooled and solidified to produce a pipe. ing. The time for the curing process has been reduced to the time required for cooling and solidification, but it has been difficult to apply to parts that still require mass production. Further, since the impregnated roving is exposed to a high temperature in the air, there is a problem that countermeasures against oxidative degradation of the resin and work environment are necessary.

  On the other hand, a method has also been proposed in which a tape impregnated with a thermoplastic resin is knitted into a pipe-shaped product. This method has high productivity, but is easily buckled when subjected to bending or compressive load, and its application range as a structure is limited. In addition, as disclosed in Patent Document 6, a method of melting and fixing a knitted pipe-shaped molded product by internal pressure molding is also disclosed, but the total molding time is long and is not suitable for mass production. Met.

  Furthermore, there is a method of manufacturing a pipe product with a circular closed cross section by joining the flange parts of two semicircular open cross section molded products, but the strength of the joint surface is weak compared to the general part, and the structure The bending strength and compressive strength as a material were not achieved at all.

  In order to increase the fuel efficiency of automobiles, there is a social demand for the development of molded products with high specific strength and specific rigidity, especially structural materials that form a skeleton with high specific strength and specific rigidity. For this reason, there has been a need to develop a pipe-like structural material that has high productivity, extremely high bending strength and compressive strength, and can be used as a structural material.

JP 2008-051124 A JP-A-8-34065 Japanese Patent No. 3375375 Japanese Patent Laid-Open No. 06-91769 Japanese Patent Laid-Open No. 06-143273 JP 2013-154624 A

  The present invention was devised in view of the current state of the above-described prior art and social demands, and its purpose is to provide a pipe-shaped molded product that is highly productive, lightweight, excellent in specific strength and specific rigidity, and a method for manufacturing the same. It is to provide.

  As a result of intensive studies to achieve the above object, the present inventors have made a pipe molded product into a two-layer structure of an outer cylindrical portion and an inner cylindrical portion, and the outer cylindrical portion contains a textile of continuous fibers for reinforcement. By forming the inner cylindrical portion by injection molding a thermoplastic resin inside the outer cylindrical portion, a pipe-shaped molded product that is lightweight but has excellent rigidity and strength can be obtained. As a result, the present invention has been completed.

That is, the present invention has the following configurations (1) to (5).
(1) A pipe molded article having a two-layer structure composed of an outer cylindrical portion and an inner cylindrical portion, wherein the outer cylindrical portion is formed of a thermoplastic resin containing a reinforcing continuous fiber textile; A pipe-molded article, wherein the inner cylindrical portion is formed of a thermoplastic resin that is injection-molded inside the outer cylindrical portion.
(2) The pipe-shaped article according to (1), wherein the outer cylindrical portion is formed of a textile made of a prepreg tape in which a roving of a reinforcing continuous fiber is impregnated with a thermoplastic resin.
(3) The pipe molded article according to (1) or (2), wherein the textile is a prepreg tape woven fabric, a knitted fabric or a braid, and the intersections of the prepreg tape are melt-bonded to each other.
(4) A method for producing a pipe-molded product comprising the following steps (i) to (vi):
(I) producing an outer cylindrical portion formed of a thermoplastic resin containing a reinforcing continuous fiber textile;
(Ii) Open the mold of the injection molding machine and place the outer cylindrical part in the mold cavity.
(Iii) Insert a sliding core into the outer cylindrical part and close the mold.
(Iv) From a terminal between the outer cylindrical portion and the sliding core, a thermoplastic resin that becomes the inner cylindrical portion is injection-molded.
(V) Open the mold and pull out the sliding core;
(Vi) A pipe molded product composed of the outer cylindrical portion and the inner cylindrical portion is taken out from the mold.
(5) The method for producing a pipe-molded product according to (4), wherein an outer cylindrical part having a metal ring shaped as a gate for injection molding is attached to the end of the mold cavity. .

  Since the pipe molded product of the present invention forms the inner cylindrical portion by injection molding a thermoplastic resin inside the outer cylindrical portion formed of the thermoplastic resin containing the reinforcing continuous fiber textile, While achieving weight reduction from both the material and shape, it can have high rigidity and strength against bending and compression deformation. Therefore, the automobile using the pipe molded product of the present invention has good fuel efficiency and can exhibit an effect of resource saving.

FIG. 1 shows a cross-sectional view of a pipe molded product of the present invention, wherein (a) shows a vertical cross-sectional view and (b) shows a cross-sectional view. FIG. 2 shows an example of a textile formed on the outer cylindrical portion of the pipe molded product of the present invention, wherein (a) shows a woven fabric, (b) shows a knitted fabric, and (c) shows a braid. FIG. 3 shows the appearance of a round prepreg tape assembly formed on the outer cylindrical portion of the pipe molded product of the present invention. FIG. 4 shows the appearance of the outer cylindrical part with a metal ring attached to the end. FIG. 5 schematically shows the appearance of an injection molding machine used for manufacturing the pipe molded product of the present invention. FIG. 6 schematically shows the appearance of the injection molding machine with the mold opened and the sliding core retracted. FIG. 7 schematically shows the appearance of an injection molding machine in which an outer cylindrical part with a metal ring is arranged in a mold, a sliding core is advanced into the outer cylindrical part, and the mold is closed. Show. FIG. 8 schematically shows the appearance of an injection molding machine in a state where an injection molding runner is arranged.

  Hereinafter, the pipe molded product of the present invention will be described in detail.

  The pipe molded product of the present invention has a two-layer structure composed of an outer cylindrical portion 1 and an inner cylindrical portion 2 as shown in the respective cross-sectional views of FIGS. The outer cylindrical portion is formed of a thermoplastic resin containing a reinforcing continuous fiber textile, and the inner cylindrical portion is formed of a thermoplastic resin that is injection-molded inside the outer cylindrical portion. As long as the pipe molded product of the present invention has this two-layer structure, other layers can be appropriately added.

  The outer cylindrical portion is preferably formed by a textile made of a prepreg tape in which a roving of continuous fibers for reinforcement is impregnated with a thermoplastic resin in advance. Examples of reinforcing continuous fibers include glass fibers, carbon fibers, aramid fibers, PBO fibers, polyethylene terephthalate fibers, polyamide fibers, vinyl alcohol fibers, and steel fibers. Among these, glass fiber, carbon fiber, aramid fiber, and PBO fiber having particularly high strength and elastic modulus are preferable, glass fiber and carbon fiber are particularly preferable, and carbon fiber having high specific strength and specific elastic modulus is most preferable.

The production method of carbon fiber is not particularly limited, but after treatment of fibers such as polyacrylonitrile fiber and cellulose fiber in air at 200 to 300 ° C., it is fired at 1000 to 3000 ° C. or more in an inert gas. Carbon fibers produced by carbonization and having a tensile strength of 20 t / cm ² or more and a tensile modulus of 200 GPa or more are preferred. The diameter of the single fiber of the carbon fiber is not particularly limited, but is preferably 3 to 9 μm from the handling property of the composite production line process. If it is less than 3 μm, impregnation and defoaming are difficult, and if it exceeds 9 μm, the specific surface area becomes small and the reinforcing effect becomes small. The carbon fiber is preferably subjected to a treatment for improving adhesion by wet oxidation with air or nitric acid, dry oxidation, heat cleaning, whiskerizing, or the like. Moreover, it is preferable that the carbon fiber is converged by a sizing agent that softens at 120 ° C. or less from the viewpoint of handling in the work process. The number of filaments forming the roving depends on the type of fiber and the fiber diameter, but is preferably 500 to 50,000, and particularly preferably 1,000 to 25,000. If the number is less than the above, the cross-sectional area of the tape is small and the productivity is low, and if the number is more than the number, impregnation at the time of producing the prepreg tape becomes difficult or the assembly becomes rough.

  Examples of the thermoplastic resin used for the outer cylindrical portion include polypropylene, polymethylpentene, polyamide 6, polyamide 66, terephthalamide copolymer, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polyoxymethylene, polycarbonate, and polyphenylene ether. And polyethyl ketone ketone. From the viewpoint of moldability, crystalline resins such as polypropylene, polyamide 6, polyamide 66, terephthalamide copolymer and polyphenylene sulfide are preferable. In particular, high specific strength polypropylene, polyamide 6, polyamide 66, and terephthalamide copolymer are preferable. These resins are preferably modified with acid, epoxy or isocyanate in order to increase the adhesive strength with the reinforcing continuous fiber. In particular, a modified polyolefin resin having low adhesion is particularly preferred. Or what mixed resin which raises adhesiveness is preferable.

  The content of the reinforcing continuous fibers in the prepreg tape is preferably 30 to 80% by volume, particularly preferably 35 to 70% by volume. If the content is less than the above range, the reinforcing efficiency is low, and if it exceeds the above range, defect points such as voids are likely to occur. The width of the prepreg tape is preferably 2 to 50 mm, more preferably 3 to 20 mm, and most preferably 3 to 15 mm. If the width is less than the above range, a large number of turns are required, and the production conditions become severe. If the width exceeds the above range, bending at the guide tends to occur.

  In the outer cylindrical portion, it is preferable that the prepreg tape is textile processed into an appropriate reinforcing form and designed in an appropriate arrangement. The textile is preferably in the form of a woven fabric, a knitted fabric, or a braid as shown in each of FIGS. 2 (a), (b), and (c). The weaving is made by weaving warps and wefts according to certain rules, and there are plain weaving, satin weaving, twill weaving and oblique weaving. Moreover, there are flat knitting and warp knitting. As the braid, there are a flat braid, a round braid, and a special braid. In the present invention, a round braid which is easy to be formed into a pipe shape is preferable. Further, when the prepreg tape is processed into a braid, as shown in FIG. 3, it is preferable that the fiber axis of the tape is set to an angle of ± 15 degrees to ± 60 degrees with respect to the longitudinal axis of the pipe. . If the angle exceeds this range, the strength and rigidity in the longitudinal direction of the pipe will be low, and if it is below this range, the strength and rigidity in the circumferential axis direction will tend to be low.

  Textile-processed prepreg tapes have many places where they touch each other and intersect. From the viewpoint of preventing deformation due to load, the intersecting portions of the tape are preferably joined to each other. In particular, it is preferable that portions of 30% or more, particularly preferably 50% or more are bonded. It is preferable that the bonding at the intersecting portion of the tape is achieved by bonding with an adhesive or melt bonding of a thermoplastic resin constituting the tape. Melt bonding of thermoplastic resin can be done by applying ultrasonic energy or laser energy to the intersection after heating and then cooling, but when melt molding a thermoplastic resin layer other than the textile part In particular, when the inner cylindrical portion is injection-molded with a thermoplastic resin, it is preferable from the viewpoint of productivity that the surface of the prepreg tape is melted and joined by the heat of the molten thermoplastic resin.

  The inner cylindrical portion is formed by injection molding a thermoplastic resin inside the outer cylindrical portion manufactured as described above. Injection molding has the advantages of high productivity, high carry-in heat capacity, and high pressure due to injection pressure. Therefore, strong integration between the inner side of the outer cylindrical part and the inner cylindrical part is possible. Thus, by directly injection-molding inside the outer cylindrical portion, the strength and rigidity of the outer cylindrical portion due to the textile can be greatly improved. Even if the inner cylindrical portion is separately produced by injection molding and then inserted into the outer cylindrical portion to achieve integration, such an effect of improving strength and rigidity is not seen. The injection molding can be basically performed by appropriately adopting conventionally known apparatuses, methods and conditions. Examples of the thermoplastic resin used for injection molding include polypropylene, polyamide 6, polyamide 66, terephthalamide copolymer, polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, and polycarbonate. . The thermoplastic resin used here requires adhesion to the thermoplastic resin of the inner cylindrical portion, and is preferably the same type of resin as the thermoplastic resin constituting the inner cylindrical portion. Further, since the thermoplastic resin is injected inside the outer cylindrical portion, it is preferable that the thermoplastic resin injected inside has a higher melting point than the thermoplastic resin constituting the outer cylindrical portion.

  The thermoplastic resin used for injection molding preferably has a melt flow rate under a 21.2N load at a temperature 30 ° C. higher than the melting point, preferably 10 to 500 g / 10 min, particularly preferably 20 to 300 g / 10 min. If the melt flow rate is less than the above range, the flowability of the thermoplastic resin is reduced during injection molding, the impregnation property to the outer cylindrical portion is low, and the porosity is high. It tends to occur and the product strength tends to decrease.

  Since the linear expansion coefficient of the textile of the outer cylindrical portion is extremely small, it is preferable that the thermoplastic resin injection-molded on the inside thereof has a small linear expansion coefficient. Specifically, the thermoplastic resin to be injection-molded is made of a fiber reinforcing material such as carbon fiber, glass fiber, or aramid fiber, or an inorganic filler such as silica, mica, talc, wollastonite, or calcium carbonate. It is preferable to contain 40% by volume, preferably 10 to 35% by volume. The difference in linear expansion coefficient between the two is preferably less than 10%. If the difference in linear expansion coefficient between the two is large, internal stress is likely to occur at the interface between the outer cylindrical textile and the thermoplastic resin injection-molded inside it, causing interfacial delamination and textile floating. May not show stiffness or strength.

  In addition to the above components, the thermoplastic resin used in the pipe molded product of the present invention includes a crystal nucleating agent, a mold release agent, a lubricant, and an antioxidant for the purpose of improving physical properties, moldability, and durability. In addition, flame retardants, light proofing agents, weathering agents, and the like can be blended.

  The outer diameter of the pipe molded product of the present invention is preferably 30 to 120 mm, more preferably 40 to 100 mm, and particularly preferably 50 to 90 mm. The inner diameter is preferably 20 to 100 mm, more preferably 30 to 90 mm, and particularly preferably 35 to 80 mm. The thickness of the inner cylindrical portion to be injection-molded is preferably 1 to 15 mm, more preferably 1.5 to 10 mm, and particularly preferably 2 to 8 mm. The length of the pipe molded product of the present invention is preferably 50 to 1500 mm, more preferably 100 to 1000 mm, and particularly preferably 150 to 800 mm. Outside the above range, the fluidity at the time of injection is insufficient and the solidification time becomes long, which may cause problems industrially.

Next, an example of the manufacturing method of the pipe molded product of this invention is demonstrated.
First, (i) as described above, the outer cylindrical portion is made of a thermoplastic resin containing a reinforcing continuous fiber textile (for example, the one shown in FIG. 3).

  Next, (ii) an injection molding machine as shown in FIG. 5 is prepared, the mold is opened, and the aforementioned outer cylindrical portion is placed in the mold cavity. After the outer cylindrical portion is adjusted to a required length by cutting or the like, and before being placed in the mold cavity, a metal ring 4 having a shape that becomes a gate for injection molding as shown in FIG. It is preferable to attach to the part. When the outer cylindrical portion is disposed in the mold cavity, the injection molding machine opens the mold (upper mold 11 and lower mold 21) in advance as shown in FIG. Further, the outer cylindrical portion needs to be arranged in the mold cavity so that the central axes of the sliding core 31 and the metal ring 4 coincide.

  Next, (iii) As shown in FIG. 7, the sliding core is inserted into the outer cylindrical portion from both sides, and the mold is closed.

  Next, (iv) the runner 5 is disposed as shown in FIG. 8, and the thermoplastic resin that becomes the inner cylindrical portion is injected by the terminal between the outer cylindrical portion and the sliding core. After injection, it is kept in that state for a predetermined time and cooled in the mold.

  Next, (v) the mold is opened, and the sliding core is pulled out from the inner cylindrical portion.

  Finally, (vi) a pipe molded product composed of the outer cylindrical portion and the inner cylindrical portion is pulled out from the mold. Specifically, an integrated runner and a pipe-formed product with a metal ring are taken out from the mold cavity. After leaving for a predetermined time, the runner is cut off at the gate, and then the metal rings at both ends of the pipe molded product are removed to obtain a pipe molded product.

  Since the molded article of the present invention is produced as described above, it is lightweight and has high rigidity and strength against bending and compressive deformation. Therefore, the pipe molded product of the present invention is suitably used for parts that require high strength and rigidity, such as automobile frames, two-wheeled vehicle frames, farm equipment frames, OA equipment frames, and frame connecting parts. be able to.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples. The axial compression stiffness test was performed as follows.

Axial Compressive Rigidity Test Using a Shimadzu Autograph AGX-1000 with a compression jig and compression load cell set, 50N was previously loaded in the axial direction of a cylindrical pipe molded product having a length of 100 mm. The load-displacement behavior was measured by compressing at a deformation rate of / min. The rigidity between displacements 0.25 mm to 0.5 mm of the obtained load-displacement curve was determined.

Example 1
A roving CF-R (TR50 manufactured by Mitsubishi Rayon) made of 12,000 carbon fibers was expanded and opened and supplied to the die head of the impregnation table at a predetermined speed. On the other hand, modified polypropylene resin PP1 (G2H, manufactured by Toyobo Co., Ltd., 230 ° C., melt flow rate 45 g / 10 min under 21.2N load) was introduced into the hopper of a screw type extruder controlled at 260 ° C. A predetermined amount was measured by a gear pump and supplied to the die head of the impregnation table. After pressure impregnation and defoaming on an impregnation stand, the prepreg tape coated with impregnation was extruded from a die having a width of 10 mm and a height of 0.2 mm, and after compression-molding and solidification, it was wound around a basket. (65% carbon fiber, 35% resin)

  The obtained prepreg tape was slit to a width of 5 mm to obtain three continuous carbon fiber prepreg tape windings impregnated with a modified propylene resin. Using this prepreg tape, as shown in FIG. 3, it was assembled into a pipe shape at an intersection angle of 45 degrees to obtain an outer cylindrical portion made of a cylindrical textile having an inner diameter of 48 mm and a length of 1000 mm. The obtained outer cylindrical portion was cut to a length of 150 mm, and metal rings having an outer diameter of 48 mm, an inner diameter of 44 mm, and a length of 2 mm were arranged at both ends of the cut outer cylindrical portion. A groove having a width of 2 mm and a height of 1 mm was provided on the circumference of each ring.

  Modified polypropylene for the hopper of an injection molding machine for hybrid molding (VIM003 model manufactured by Sato Iron Works), which is a combination of a vertical compression molding machine and a horizontal injection molding machine with cylinder temperatures (° C) adjusted to 230-260-260-260 Resin (Toyobo, G2H) was added. The mold on the compression molding machine side whose temperature was adjusted to 50 ° C. was opened, and the outer cylindrical part with the metal ring was placed in the cavity. The sliding core was inserted into the metal ring and the outer cylindrical part, and the mold was closed.

  The modified polypropylene was injection-molded through the runner from the both ends to the inside of the outer cylindrical portion under the conditions of an injection time of 8 seconds and a cooling time of 20 seconds. The resin was filled in the gap between the inner 2 mm thick portion of the pipe molded product and the outer cylindrical portion, and the modified polypropylene resin constituting the outer cylindrical portion was welded to fix the textile of the outer cylindrical portion.

  After cooling, the mold was opened, the sliding core was pulled out, and a pipe molded product with metal rings at both ends was taken out from the mold. After demolding, a groove formed on the metal ring was cut to obtain a two-layered pipe molded product having a continuous carbon fiber textile impregnated with a modified polypropylene resin on the outside and a modified polypropylene resin on the inside. Table 1 shows the details of the obtained pipe molded product and the evaluation results of the axial compression stiffness test.

Example 2
In Example 1, a pipe-molded product was produced in the same manner as in Example 1, except that the resin to be injection-molded was changed from the modified polypropylene PP1 to the carbon fiber reinforced polypropylene resin PP2 obtained by compounding the chopped carbon fiber with the modified polypropylene in advance. Then, the axial compression stiffness test was evaluated in the same manner as in Example 1. Table 1 shows the details of the obtained pipe molded product and the evaluation results of the axial compression stiffness test.

  For compounding, a twin screw extruder PCM30 manufactured by Ikekai Tekko Co., Ltd., whose temperature was adjusted to 230 ° C., was premixed with a modified polypropylene resin and chopped carbon fiber at a weight ratio of 80:20, and the screw was rotated. The strand was pelletized by melt-kneading at several hundreds per minute.

Comparative Example 1
Using the same molding machine and mold as in Example 1, the outer cylindrical portion made of textile is not placed in the mold, and the same modified polypropylene used in Example 1 is injection molded, and the same shape is used as the outer layer. A pipe-molded product without textiles was produced. Table 1 shows the details of the obtained pipe molded product and the evaluation results of the axial compression stiffness test.

Comparative Example 2
A cylindrical textile produced from prepreg tape was produced in exactly the same manner as in Example 1, and cut into the same length as in Example 1 to obtain a pipe molded product. Table 1 shows the details of the obtained pipe molded product and the evaluation results of the axial compression stiffness test.

Comparative Example 3
Using the same molding machine and mold as in Example 1, an inner cylindrical part obtained by injection molding without arranging the outer cylindrical part made of textiles was obtained in the same manner as in Example 1. It was inserted inside the outer cylindrical part made of the cylindrical textiles obtained, and a pipe molded product was obtained in which the inner cylindrical part was made of resin and the outer cylindrical part was a textile. The outer cylindrical portion made of textiles and the inner cylindrical portion formed by injection molding separately are not melt-bonded only by physical contact. Table 1 shows the details of the obtained pipe molded product and the evaluation results of the axial compression stiffness test.

Comparative Example 4
In exactly the same manner as in Example 1, a cylindrical textile was produced from the prepreg tape and cut into the same length as in Example 1 to obtain a cylindrical textile. A cylindrical textile was arranged concentrically outside the steel pipe in a metal plate mold in which a steel pipe having an outer diameter of 44 mm, an inner diameter of 42 mm, and a height of 150 mm was fixed vertically. A molten modified polypropylene resin PP1 is injected at a low speed into a gap between the cylindrical pipe and the steel pipe from a 1 mmφ nozzle of a twin screw extruder PCM30 manufactured by Ikekai Tekko Co., Ltd. whose temperature is adjusted to 230 ° C. After being allowed to cool for 30 minutes, the laminated pipe molded product was removed from the metal plate mold, and both ends were cut to obtain a laminated pipe made of carbon fiber textile and PP1 resin having a length of 100 mm. Table 1 shows the details of the obtained pipe molded product and the evaluation results of the axial compression stiffness test.

The symbols in Table 1 are as follows.
PP1: modified polypropylene resin G2H (manufactured by Toyobo, 230 ° C., melt flow rate 45 g / 10 min under 21.2 N load, melting point 165 ° C.)
PP2: PP1 3mm cut chopped carbon fiber (Mitsubishi Rayon TR50) 20 wt% compound product, 230 ° C, melt flow rate under 21.2N load 20g / 10min
CF-R: Carbon fiber, Mitsubishi Rayon TR50 (12,000 filaments)

  As can be seen from the results in Table 1, the pipe molded product of the example in which the inner cylindrical portion and the outer cylindrical portion are integrated by injection molding is used to connect the inner cylindrical portion and the outer cylindrical portion once using the same material. Comparative Example 1 made in the above, Comparative Example 2 in which the inner cylindrical part is not formed, Comparative Example 3 in which the inner cylindrical part and the outer cylindrical part are integrated by insertion, or the inner cylindrical part and the outer cylindrical part The rigidity is clearly higher than that of Comparative Example 4 in which the integration is performed by injection hardening.

  The pipe molded product of the present invention has high shaft compression rigidity while being lightweight, and has high safety during use. Accordingly, it can be suitably used for automobile frames, two-wheeled vehicle frames, agricultural machinery frames, OA equipment frames, frame connecting components, T-shaped frames and cross-shaped frame connecting components.

DESCRIPTION OF SYMBOLS 1 Outer cylindrical part 2 Inner cylindrical part 3 Prepreg tape 4 Metal ring 5 Runner 11 Upper mold | type 21 Lower mold | type 31 Sliding core 41 Hopper 42 Barrel 43 Nozzle 44 Pressure board

Claims (5)

  A pipe molded article having a two-layer structure comprising an outer cylindrical portion and an inner cylindrical portion, wherein the outer cylindrical portion is formed of a thermoplastic resin containing a reinforcing continuous fiber textile, A pipe-shaped product, wherein the shaped part is formed of a thermoplastic resin injection-molded inside the outer cylindrical part.   2. The pipe molded product according to claim 1, wherein the outer cylindrical portion is formed of a textile made of a prepreg tape in which a roving of a reinforcing continuous fiber is impregnated with a thermoplastic resin.   The pipe molded article according to claim 1 or 2, wherein the textile is a prepreg tape woven fabric, a knitted fabric or a braid, and the intersections of the prepreg tape are melt-bonded to each other. A method for producing a pipe-molded article comprising the following steps (i) to (vi):
(I) producing an outer cylindrical portion formed of a thermoplastic resin containing a reinforcing continuous fiber textile;
(Ii) Open the mold of the injection molding machine and place the outer cylindrical part in the mold cavity.
(Iii) Insert a sliding core into the outer cylindrical part and close the mold.
(Iv) From a terminal between the outer cylindrical portion and the sliding core, a thermoplastic resin that becomes the inner cylindrical portion is injection-molded.
(V) Open the mold and pull out the sliding core;
(Vi) A pipe molded product composed of the outer cylindrical portion and the inner cylindrical portion is taken out from the mold.   5. The method for producing a pipe-molded product according to claim 4, wherein an outer cylindrical part having a metal ring shaped as a gate for injection molding is attached to the end of the mold cavity.