JP2019130691A - Hollow molding and method for producing the same - Google Patents

Abstract

To provide a hollow molding having excellent bendability and high strength and a method for producing the same.SOLUTION: A hollow molding having a bent part, has a thermoplastic resin and a continuous reinforced fiber; preferably, a braid is used that contains the continuous reinforced fiber of 30 mass% or more. In a bending machine used as means for bending a cylindrical body, a portion of the cylindrical body to be bent is heated and softened in advance; and preferably, the bending is conducted with a cored inserted into the cylindrical body.SELECTED DRAWING: None

Description

  The present invention relates to a hollow molded body and a method for producing the same.

  In recent years, hollow bodies made of reinforcing fibers and thermosetting resins have been used as hollow mechanical parts and structures used in various machines, automobiles, and appliances. As a method for producing such a hollow body, there is known a method in which a linear tubular braid made of reinforcing fiber yarns is pulled out from a mandrel, placed in a hollow body mold, and impregnated and cured with a thermosetting resin. Yes. However, in this method, when the hollow body has a bent portion, there is a problem in productivity because it is difficult to maintain the shape of the braid installed in the bent portion of the corresponding mold. Therefore, Patent Document 1 devises a method of composing a bent braid having a curved shape in advance by composing a braid of reinforcing fiber yarn around a curved mandrel.

JP 7-11553 A

However, in the method described in Patent Document 1, when the bent portion has various angles and directions, or when there are a plurality of bent portions, a mandrel corresponding to the bent portion is prepared, and a cylindrical braid is provided around the mandrel. It is difficult to draw out the composition.
The present invention has been devised in view of such conventional circumstances, and an object of the present invention is to provide a high-strength hollow molded body excellent in bending workability and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by making a hollow molded body containing continuous reinforcing fibers and a thermoplastic resin, and the present invention has been completed. I let you.
That is, the present invention is as follows.

[1] A hollow molded article having a bent portion, comprising a thermoplastic resin and continuous reinforcing fibers.
[2] The hollow molded body according to [1], wherein the continuous reinforcing fibers are braided.
[3] The thermoplastic resin is a polyolefin resin, polyamide resin, polyester resin, polyether ketone, polyether ether ketone, polyether sulfone, polyphenylene sulfide, thermoplastic polyetherimide, and thermoplastic fluorine resin. The hollow molded article according to [1] or [2], which is at least one selected from the group consisting of:
[4] The continuous reinforcing fiber is at least selected from the group consisting of glass fiber, carbon fiber, aramid fiber, ultrahigh strength polyethylene fiber, polybenzazole fiber, liquid crystal polyester fiber, polyketone fiber, metal fiber, and ceramic fiber. The hollow molded body according to any one of [1] to [3], which is one type.
[5] The hollow molded body according to any one of [1] to [4], wherein the content of the continuous reinforcing fiber is 30% by mass or more.
[6] The method for producing a hollow molded body according to any one of [1] to [5], wherein a cylindrical body including a thermoplastic resin and continuous reinforcing fibers is used.
[7] The method for producing a hollow molded article according to [6], wherein a braid including thermoplastic resin fibers and continuous reinforcing fibers is used.
[8] The method for producing a hollow molded body according to [6] or [7], further including a step of bending the cylindrical body.
[9] The method for manufacturing a hollow molded body according to [8], wherein the step of bending the cylindrical body includes a step of bending the cylindrical body using a bending machine.
[10] The method for manufacturing a hollow molded body according to [8] or [9], wherein the step of bending the cylindrical body includes a step of heat-softening the cylindrical body.
[11] The method for producing a hollow molded body according to any one of [8] to [10], including a step of inserting a center core into the cylindrical body.
[12]
The manufacturing method of the hollow molded object in any one of [9]-[11] including the process of preheating the part which contacts the said cylinder of the said bending machine.

  ADVANTAGE OF THE INVENTION According to this invention, the high intensity | strength hollow molded object excellent in bending workability and its manufacturing method can be provided.

  Hereinafter, an embodiment of the present invention (hereinafter, also referred to as “this embodiment”) will be described in detail, but the present invention is not limited to this embodiment.

<Hollow molding>
The hollow molded body of the present embodiment is a hollow molded body having a bent portion, which includes a thermoplastic resin and continuous reinforcing fibers.
In the present disclosure, the “bent portion” means that the bent portion of the hollow molded body has almost no collapse of the inner diameter or breakage of the continuous reinforcing fiber, but there is a collapse of the inner diameter or breakage of the continuous reinforcing fiber. The part where space remains.

[Thermoplastic resin]
There is no restriction | limiting in particular in the thermoplastic resin contained in the hollow molded object of this embodiment, A normal thing can be used, For example, polyolefin resin, such as polyethylene and a polypropylene; Polyamide 6, Polyamide 66, Polyamide 46, etc. Polyamide resins: Polyethylene resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate; Polyacetal resins such as polyoxymethylene; Polycarbonate resins; Polyether ketones; Polyether ether ketones; Polyether sulfone; A thermoplastic polyetherimide; a thermoplastic fluororesin such as a tetrafluoroethylene-ethylene copolymer, and a modified thermoplastic resin obtained by modifying these; It is preferably a continuous fiber obtained by melt spinning RESIN. Among these thermoplastic resins, polyolefin resin, polyamide resin, polyester resin, polyether ketone, polyether ether ketone, polyether sulfone, polyphenylene sulfide, thermoplastic polyether imide, and thermoplastic fluorine resin are preferable. From the viewpoints of mechanical properties and versatility, polyolefin resins, modified polyolefin resins, polyamide resins, and polyester resins are more preferable. From the viewpoint of thermal properties, polyamide resins and polyester resins are further added. preferable. Further, from the viewpoint of durability against repeated load loading, a polyamide-based resin is more preferable, and polyamide 66 can be suitably used.

-Polyester resin-
The polyester-based resin means a high molecular compound having a —CO—O— (ester) bond in the main chain. For example, polyethylene terephthalate, polybutylene terephthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate and the like can be mentioned, but are not limited thereto. .
Regarding the details of other polyester resins, those described in JP-A-2015-101792 can be used as appropriate.

-Polyamide resin-
The polyamide-based resin means a polymer compound having a —CO—NH— (amide) bond in the main chain. Examples thereof include polyamides obtained by ring-opening polymerization of lactam, polyamides obtained by self-condensation of ω-aminocarboxylic acid, polyamides obtained by condensing diamine and dicarboxylic acid, and copolymers thereof. It is not limited to.
As the polyamide, one kind may be used alone, or two or more kinds may be used as a mixture.
Regarding the details of the other lactam, diamine (monomer), and dicarboxylic acid (monomer), those described in JP-A-2015-101792 can be used as appropriate.

  Specific examples of the polyamide include, for example, polyamide 4 (poly α-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecanamide), polyamide 12 (polydodecanamide), and polyamide 46 (polytetramethylene adipa). Amide), polyamide 66 (polyhexamethylene adipamide), polyamide 610, polyamide 612, polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), and polyamide 6I (polyhexamethylene isophthalamide) And copolymerized polyamides containing these as constituents.

  Examples of the copolymerized polyamide include a copolymer of hexamethylene adipamide and hexamethylene terephthalamide, a copolymer of hexamethylene adipamide and hexamethylene isophthalamide, and hexamethylene terephthalamide and 2-methylpentanediamine terephthalate. Examples include amide copolymers.

  The continuous reinforcing fiber and the thermoplastic resin included in the hollow molded body of the present embodiment are a mixed fiber including a continuous reinforcing fiber and a thermoplastic resin fiber, a coated yarn obtained by coating the continuous reinforcing fiber with a thermoplastic resin, or a continuous reinforcing fiber. It can take the form of a composite yarn such as an impregnated yarn in which a fiber is impregnated with a thermoplastic resin. From the viewpoint of ease of making the assembly, a mixed fiber is preferable.

The number of single yarns F (the number) of the thermoplastic resin fibers is preferably 30 to 20,000 from the viewpoints of the spreadability and the handleability in the fiber mixing process.
Moreover, it is preferable that the fineness T (dtex) of a thermoplastic resin fiber is 100-50000 dtex from a viewpoint of the intensity | strength of a hollow molded object.

  It is preferable that content of the thermoplastic resin in a hollow molded object is 10-90 mass%, More preferably, it is 30-85 mass%, More preferably, it is 40-80 mass%.

[Continuous reinforcing fiber]
As the continuous reinforcing fiber contained in the hollow molded body of the present embodiment, those used as a normal fiber reinforced composite material can be used. For example, glass fiber, carbon fiber, aramid fiber, ultra high strength polyethylene fiber, poly Examples thereof include at least one selected from the group consisting of benzazole fibers, liquid crystal polyester fibers, polyketone fibers, metal fibers, and ceramic fibers. Glass fibers, carbon fibers, and aramid fibers are preferable from the viewpoint of mechanical properties, thermal properties, and versatility, and glass fibers are more preferable from the viewpoint of price.

When glass fiber is selected as the continuous reinforcing fiber, a sizing agent may be used, and the sizing agent is preferably composed of a silane coupling agent, a lubricant, and a binding agent.
There is no restriction | limiting in particular about the kind of sizing agent used for glass fiber and glass fiber, A well-known thing can be used. Specifically, for example, those described in JP-A-2015-101792 can be used.

Similarly, when a carbon fiber is selected as the continuous reinforcing fiber, a sizing agent may be used, and the collecting agent is preferably composed of a lubricant and a binding agent.
There is no restriction | limiting in particular about the kind of sizing agent used for carbon fiber, A well-known thing can be used. Specifically, for example, those described in JP-A-2015-101792 can be used.

  Even when other continuous reinforcing fibers are used, depending on the characteristics of the continuous reinforcing fibers, the types and application amounts of sizing agents that can be used for glass fibers and carbon fibers can be appropriately selected and used. It is preferable to set the type and amount of sizing agent according to the sizing agent used in the above.

The number of single yarns F (the number) of continuous reinforcing fibers is preferably 30 to 15,000 from the viewpoints of openability and handling in the fiber mixing process.
Moreover, it is preferable that the fineness T (dtex) of a continuous reinforcing fiber is 100-50000 dtex from a viewpoint of the intensity | strength of a hollow molded object.

Product RD single filament diameter R of the continuous reinforcing fibers ([mu] m) and density D (g / cm ³⁾ are preferably 5~100μm · g / cm ^3, more preferably 10~50μm · g / cm ^3, more preferably the 15~45μm · g / cm ^3, even more preferably 20~45μm · g / cm ^3.
If the product RD of the continuous reinforcing fibers is 5 μm · g / cm ³ or more, the continuous reinforcing fibers are not easily damaged during the fiber mixing, and the composite fiber molded body obtained from the braid is sufficient. Demonstrate mechanical properties.
If the product RD of continuous reinforcing fibers is 100 μm · g / cm ³ or less, the continuous reinforcing fibers are easy to open, and both fibers are likely to be mixed uniformly and continuously. Therefore, a composite material molded body that exhibits sufficient mechanical properties can be obtained in a short time.

If the continuous reinforcement fiber product RD is 5 to 100 μm · g / cm ³ , continuous reinforcement without damaging the continuous reinforcement fiber when the continuous reinforcement fiber and the continuous thermoplastic resin fiber are mixed. The fibers can be easily opened, and both fibers can be mixed uniformly and continuously. The reason is not necessarily clear, but it is estimated that the reason is as follows. That is, when an external force is applied to the continuous reinforcing fiber, it is assumed that an external force proportional to the peripheral diameter, that is, the single yarn diameter is applied to one single yarn. On the other hand, the inertial mass per unit length per single yarn is proportional to the product of the square of the single yarn diameter and the density. According to the equation of motion, the acceleration generated in the single yarn is proportional to the value obtained by dividing the external force by the inertial mass, so the acceleration generated in the single yarn of the continuous reinforcing fiber at the time of blending is the product RD of the single yarn diameter and density. Inferred to be inversely proportional. Therefore, when the product RD is too small from a certain range, it is assumed that the continuous reinforcing fiber is easily damaged because the acceleration becomes excessive. On the other hand, when the product RD is excessively larger than a certain range, it is estimated that the continuous reinforcing fiber is difficult to open because the acceleration is excessively small.

In this embodiment, the density D (g / cm ³ ) of the continuous reinforcing fiber is a catalog value, and the single yarn diameter R (μm) is the fineness T (dtex) of the continuous reinforcing fiber, the number of single yarns F (number), and the density. Using D (g / cm ³ ), the following formula (1) is used.
R = 20 × (T / π · F · D) ^0.5 (1)

In order to set the continuous reinforcing fiber product RD within a predetermined range, the fineness T (dtex) and the number of single yarns F (the number) are appropriately selected for commercially available continuous reinforcing fibers according to the density of the continuous reinforcing fibers. do it. For example, when glass fiber is used as the continuous reinforcing fiber, the density is about 2.5 g / cm ³ , so that a single yarn diameter of 2 to 40 μm may be selected. Specifically, when the single fiber diameter of the glass fiber is 9 μm, the product RD becomes 23 by selecting the glass fiber having a fineness of 660 dtex and 400 single yarns. When the single fiber diameter of the glass fiber is 17 μm, the product RD is 43 by selecting the glass fiber having the fineness of 11,500 dtex and the number of single yarns of 2,000. When carbon fiber is used as the continuous reinforcing fiber, the density is about 1.8 g / cm ³ , so that a single yarn diameter of 2.8 to 55 μm may be selected. Specifically, when the single yarn diameter of the carbon fiber is 7 μm, the product RD is 13 by selecting the carbon fiber having a fineness of 2,000 dtex and a single yarn number of 3,000. When an aramid fiber is used as the continuous reinforcing fiber, the density is about 1.45 g / cm ³ , so that a single yarn diameter of 3.4 to 68 μm may be selected. Specifically, when the single yarn diameter of the aramid fiber is 12 μm, the product RD is 17 by selecting the aramid fiber having a fineness of 1,670 dtex and 1,000 single yarns.
In order to make the product RD within a preferable range, for example, a glass fiber having a single fiber diameter of 9 μm and a fineness of 660 dtex and 400 single yarns may be used.

Further, the continuous reinforcing fibers included in the hollow molded body of the present embodiment may be braided, woven, or knitted. Among them, a braided shape is preferable.
In the present disclosure, the braid means a string in which fibers are alternately crossed by 3 units or more, and the crossing angle of each fiber at the time of crossing is slanted.
The crossing angle of the braid is not particularly limited, and may be set as appropriate according to the required physical properties. When high strength is required in the longitudinal direction of the braid, the crossing angle may be set small, for example, preferably 0 to 60 °, more preferably 10 to 45 °, and still more preferably 10 to 30 °. Moreover, when high intensity | strength is required in the circumferential direction of a braid, what is necessary is just to set an intersection angle large, for example, Preferably it is 15-90 degrees, More preferably, it is 30-80 degrees, More preferably, it is 45-80 degrees.

Moreover, since the braid of this embodiment shape | molds a hollow molded object, it is preferable that it is a hollow braid which consists of braids without including a center yarn. For the braided yarn, any of continuous reinforcing fiber alone, continuous thermoplastic resin fiber alone, and a composite yarn including continuous reinforcing fiber and thermoplastic resin fiber may be used. When the braid is composed using the composite yarn, the composite yarn is present as a continuous structure in the braid, and the continuous reinforcing fiber is continuously present as the composite yarn. Excellent mechanical properties can be exhibited as a composite material molded body.
The inner diameter (mm) of the hollow braid is dependent on the desired shape of the hollow molded body, but is preferably, for example, Φ1 to Φ500 mm, more preferably Φ5 to Φ400 mm.

  The content of continuous reinforcing fibers in the hollow molded body is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, and still more preferably 30 to 80% by mass.

[Interfacial adhesive strength by microdroplet test]
Since the sizing agent functions to improve the adhesion between the continuous reinforcing fiber and the thermoplastic resin, the interfacial adhesion by the microdroplet test measured by attaching the resin constituting the continuous thermoplastic resin fiber to the single yarn of the continuous reinforcing fiber. The strength is preferably 9 MPa or more, more preferably 13 MPa or more, and further preferably 15 MPa or more. The interfacial adhesive strength can be adjusted by appropriately selecting the type of sizing agent and the amount of adhesion. The higher the interfacial adhesive strength, the better. However, if the interfacial adhesive strength is excessively high, problems such as the continuous reinforcing fiber single yarn being cut during the measurement occur. Therefore, the interfacial adhesive strength is preferably 100 MPa or less.

The interfacial adhesive strength by the microdroplet test is measured by the microdroplet test using a composite material interface property evaluation apparatus. A single yarn is taken out from the continuous reinforcing fiber and set in a composite material interface property evaluation apparatus. A drop in which a thermoplastic resin that is a raw material for continuous thermoplastic resin fibers is melted on the apparatus is formed on the continuous reinforcing fiber single yarn, and is sufficiently cooled at room temperature to obtain a sample for measurement. Set the measurement sample in the device again, pinch the drop with the device blade, run the continuous reinforcing fiber single yarn on the device at a speed of 0.06 mm / min, and measure the maximum pulling load f (N) when pulling out the drop Then, the interface adhesive strength τ is calculated by the following formula (2).
Interfacial adhesive strength τ = f / π · R · l (2)
(F: maximum pulling load (N), R: continuous reinforcing fiber single yarn diameter (m), l: particle diameter in the pulling direction of the drop (m))
In the present disclosure, the interfacial adhesive strength can be specifically measured by the method described in Examples described later.

[Ratio of product RD of continuous reinforcing fiber and continuous thermoplastic resin fiber]
In the present embodiment, the product RD (continuous reinforcing fiber) of the single yarn diameter R (μm) and the density D (g / cm ³ ) of the continuous reinforcing fiber, the single yarn diameter R (μm) and the density D of the continuous thermoplastic resin fiber. The ratio of product RD (continuous thermoplastic resin fibers) of (g / cm ³ ), RD (continuous reinforcing fiber) / RD (continuous thermoplastic resin fibers) is preferably 0.3 to 5, more preferably 0.5. -4, more preferably 0.6-2.
In the fiber mixing step, it is preferable that the continuous reinforcing fiber and the continuous thermoplastic resin fiber are opened and mixed with each other, and for that purpose, the acceleration generated in both fibers by the external force acting at the time of fiber mixing is substantially equal. Is presumed to be preferable. If the ratio of the product RD of the two fibers is within the above range, it is presumed that the acceleration generated in each fiber is substantially equal, and the continuous reinforcing fiber and the continuous thermoplastic resin fiber are easily mixed with each other.
In the present disclosure, the ratio of the product RD can be measured by the method described in Examples described later.

[Production method of composite yarn]
The manufacturing method of the said mixed fiber is not restrict | limited in particular, A well-known mixed fiber method can be utilized. For example, after opening by external force such as electrostatic force, pressure by fluid spraying, pressure applied to rollers, etc., continuous fiber and thermoplastic resin fibers are opened and then combined and aligned. Or a fluid entanglement (interlace) method. Among them, a fluid entanglement method that can suppress damage of continuous reinforcing fibers, has excellent fiber opening properties, and can be mixed uniformly is preferable. As the fluid entanglement (interlace) method, two or more vortex turbulent zones by fluids such as air, nitrogen gas and water vapor are made almost parallel to the yarn axis, and the fibers are led to this zone to cause loops and crimps. Non-bulky yarn under a certain degree of tension, or a method of fluid entanglement after opening only continuous reinforcing fibers or after opening both continuous reinforcing fibers and thermoplastic resin fibers (after opening) Fluid entanglement method). In particular, it is preferable that the thermoplastic resin fiber is subjected to false twisting in a process including thermal processing alone, and then continuously blended by the fluid entanglement method in the same apparatus.
In addition, about the detail of the fiber mixing method, the method of Unexamined-Japanese-Patent No. 2015-101792 can be used suitably.
Moreover, the manufacturing method of the said coating yarn and an impregnation yarn is not restrict | limited in particular, A well-known method can be utilized. The coating and impregnation may be performed at the time of producing the continuous reinforcing fiber, or may be performed in a separate process after the continuous reinforcing fiber is produced.

[Other additives]
You may make the hollow molded object of this embodiment contain an additive as needed. The hollow molded body of the present embodiment includes, for example, an anti-aging agent, an antioxidant, a weathering agent, a metal deactivator, a light stabilizer, a heat stabilizer, an ultraviolet absorber, an antibacterial / antifungal agent, a deodorant, and a conductive material. Property-imparting agent, dispersant, softener, plasticizer, crosslinking agent, co-crosslinking agent, vulcanizing agent, vulcanization aid, foaming agent, foaming aid, colorant, flame retardant, vibration damping agent, nucleating agent, You may contain additives, such as a neutralizing agent, a lubricant, an antiblocking agent, a dispersing agent, a fluidity improver, and a mold release agent.
The content of the additive is preferably 20 parts by mass or less based on 100 parts by mass of the thermoplastic resin.

<Inner diameter, outer diameter, thickness of hollow molded body>
As for the hollow molded object of this embodiment, it is preferable that the maximum value / minimum value of an internal diameter is 1.0-5.0 over the full length of a hollow molded object. In the hollow molded body of the present embodiment, the inner diameter of the straight portion is often the maximum value of the inner diameter of the entire hollow molded body, and the inner diameter of the bent portion is often the minimum value of the inner diameter of the entire hollow molded body.
The inner diameter (mm) of the straight portion of the hollow molded body of this embodiment is preferably Φ1 to Φ500 mm, more preferably Φ5 to Φ400 mm, and further preferably Φ10 to Φ300 mm.
The outer diameter (mm) of the straight portion of the hollow molded body of this embodiment is preferably Φ1 to Φ500 mm, more preferably Φ5 to Φ400 mm, and further preferably Φ10 to Φ300 mm.
The thickness (mm) of the straight portion of the hollow molded body of the present embodiment is preferably 0.1 to 10 mm, more preferably 0.5 to 5 mm, and still more preferably 1 to 3 mm.

The inner diameter (mm) of the bent portion of the hollow molded body of this embodiment is preferably 30 to 100%, more preferably 40 to 90% of the inner diameter (mm) of the straight portion of the hollow molded body. More preferably, it is 50 to 80%.
The outer diameter (mm) of the bent portion of the hollow molded body of this embodiment is preferably 30 to 100% of the outer diameter (mm) of the straight portion of the hollow molded body.
The thickness (mm) of the bent portion of the hollow molded body of this embodiment is preferably 30 to 100% of the thickness (mm) of the straight portion of the hollow molded body.
In the present disclosure, the inner diameter and the outer diameter of the hollow molded body refer to the maximum diameter when the cross-sectional shape with respect to the length direction of the hollow molded body is not circular.

<Bending elastic modulus of hollow molded body>
The bending elastic modulus in the straight portion of the hollow molded body of the present embodiment is preferably 1000 to 80000 MPa, more preferably 5000 to 70000 MPa, still more preferably 10,000 to 60000 MPa, and even more preferably 15000 to 40000 MPa. It is. When the bending elastic modulus in the straight part of the hollow molded body is 1000 to 80000 MPa, technically, there is little deformation of the straight part when the bent part is processed, and in terms of applications, it can be developed into high-strength parts. You can aim.
In the present disclosure, the flexural modulus of the molded body is a value measured in accordance with ISO178, and can be specifically measured by the method described in the examples described later.
Examples of methods for adjusting the flexural modulus to the above range include increasing the content of reinforcing fibers, increasing the molding time, and optimizing the molding pressure.

<Method for producing hollow molded body>
The manufacturing method of the hollow molded object of this embodiment uses the cylinder containing a thermoplastic resin and continuous reinforcement fiber, It is characterized by the above-mentioned.

The cylindrical body may be manufactured by manufacturing a hollow braid including thermoplastic resin fibers and continuous reinforcing fibers, and melt-solidifying the thermoplastic resin fibers by pultrusion molding. It may be manufactured by drawing a thread, braid, woven fabric, or knitted fabric containing fibers and continuous reinforcing fibers around a mandrel into a tubular shape and melting and solidifying the thermoplastic resin fibers. Alternatively, hollow braids containing continuous reinforcing fibers, or yarns, braids, woven fabrics, or knitted fabrics containing continuous reinforcing fibers that are formed into a cylindrical shape by winding them around a mandrel are impregnated with a thermoplastic resin and drawn. The thermoplastic resin may be melted and solidified by molding. Among them, it is possible to manufacture a cylindrical body by making a hollow braid including thermoplastic resin fibers and continuous reinforcing fibers, and drawing and molding the hollow braid to melt and solidify the thermoplastic resin fibers. preferable.
The method and apparatus used for producing the above-described yarn, braid, woven fabric, or knitted fabric are not particularly limited, and a known method that can produce an appropriate braid, woven fabric, or knitted fabric selected according to the application and purpose. And devices can be used.
Moreover, the pultrusion method and the pultrusion machine used for pultrusion are not particularly limited, and a known method and apparatus for producing an appropriate cylinder selected according to the application and purpose can be used.
The pultrusion speed (mm / min) depends on the desired shape of the hollow molded body, but is preferably 5 to 500 mm / min or less, more preferably 10 to 400 mm / min.
The pultrusion temperature (° C.) depends on the desired shape of the hollow molded body, but is preferably 265 to 350 ° C., more preferably 280 to 320 ° C.

Furthermore, it is preferable that the manufacturing method of the hollow molded object of this embodiment includes the process of bending the said cylinder.
As a method of bending the cylindrical body, for example, it can be bent at a desired angle by bending using a bending machine.

  The bending machine used to bend the cylindrical body is not particularly limited. 3/4 "lever type bender, manual / electric / hydraulic (manual / electric) tube bender, 1/4", 5/16 ", Pipe vendors such as 3/8 ", 7/16", 1/2 ", 5/8" spring bender, and the like can be mentioned.

Further, the step of bending the cylindrical body may include a step of heating and softening the cylindrical body. By heating and softening the cylindrical body, the cylindrical body can be bent more easily.
The heating temperature at the time of softening the tube is preferably within the melting point of the thermoplastic resin ± 150 ° C, more preferably within the melting point ± 100 ° C, and even more preferably within the melting point ± 50 ° C.

Further, it is preferable to bend the cylindrical body in a state in which the core is inserted into the cylindrical body because the diameter of the bent portion is difficult to be crushed.
The core to be inserted into the cylindrical body is not particularly limited as long as it is flexibly bent and the diameter is not easily crushed, and examples thereof include a wire, a bellows-like tube, a bendable metal pipe, and a rod. From the viewpoint of drawing out the core after bending, a wire is particularly preferable.
Further, the diameter (mm) of the core is preferably Φ1 to Φ500 mm, more preferably Φ5 to Φ400 mm, and further preferably Φ10 to Φ300 mm.

Furthermore, the bending machine preferably heats and warms the portion that comes into contact with the cylinder in advance from the viewpoint of ease of bending. The heating method is not particularly limited, and examples thereof include a method using a burner, a method in which a bending machine is equipped with a heater, and the like. It is preferable that the temperature of the part which contacts a cylinder by heating will be 50-350 degreeC, and it is more preferable that it will be 100-300 degreeC.
Moreover, you may heat-soften a cylinder with the heat of the part which contacts the cylinder of this bending machine. In that case, it is preferable to heat the portion in contact with the cylinder to within the melting point ± 150 ° C. of the thermoplastic resin, more preferably within the melting point ± 100 ° C., and even more preferably within the melting point ± 50 ° C.

<Cross section inner diameter minor axis radius of bent tube>
The cylindrical body bent as described above is a bent portion with respect to the straight portion C1 (the inner diameter, which is the diameter of the portion showing the hollow space in the cross section, half the inner diameter in the short axis direction) C1 The ratio ((C2 / C1) × 100) of the minor axis radius C2 of the cross-sectional inner diameter of the central portion of the bend angle is preferably 3% or more, more preferably 20% or more, and 53% or more. Is more preferable. If this ratio is less than 3%, the bent portion is in a state where there is almost no hollow space due to the collapse of the inner diameter or the breakage of the continuous reinforcing fiber, so the hollow molded body in which the bent cylinder has a bent portion is Don't be.

  Hereinafter, the contents of the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to these examples.

<Material>
The materials used in Examples and Comparative Examples are as follows.

[Thermoplastic resin]
Polyamide 66 fiber (PA66) (trade name: Leona (registered trademark) 470 / 136BAP, manufactured by Asahi Kasei Fibers Co., Ltd., density: 1.1 g / cm ³ , fineness: 470 dtex, number of single yarns: 136, melting point: 265 ° C. )
Polyamide 610 fiber (PA610) (density: 1.1 g / cm ³ , fineness: 470 dtex, number of single yarns: 136, melting point: 215 ° C.)

[Thermosetting resin]
・ Epoxy resin (trade name: jER (registered trademark) resin, manufactured by Mitsubishi Chemical Corporation)

[Continuous reinforcing fiber]
Glass fiber (GF) (manufactured by Nippon Electric Glass Co., Ltd., density: 2.5 g / cm ³ , fineness: 680 dtex, number of single yarns: 400)
Carbon fiber (fineness: 1980 dtex, number of single yarns: 3000)

[Bundling agent]
-Sizing agent A: It has the following composition (solid content conversion).
Silane coupling agent: 0.6% by mass of γ-aminopropyltriethoxysilane (trade name: KBE-903, manufactured by Shin-Etsu Chemical Co., Ltd.)
・ Lubricant: 0.1% by weight of wax (trade name: Carnauba wax, manufactured by Yoko Kato)
・ Binder: 5% by mass of acrylic acid / maleic acid copolymer salt (trade name: Aqualic TL, manufactured by Nippon Shokubai Co., Ltd.)

・ Pipe bender: 3/4 ”lever type tube bender (trade name: tube bender, manufactured by Super Tool Co., Ltd.)
・ Core wire: sling wire rope (length 0.5m, diameter 14mm)

<Measurement and evaluation method>
The measurement and evaluation methods used in Examples and Comparative Examples are as follows.

(1) Single yarn diameter R of continuous reinforcing fiber and continuous thermoplastic resin fiber
The single yarn diameter R (μm) of the continuous reinforcing fiber and the continuous thermoplastic resin fiber is represented by the following formula (1) using the density D (g / cm ³ ), the fineness T (dtex), and the number of single yarns F (number) of the catalog value. ).
R = 20 × (T / π · F · D) ^0.5 (1)
In general, a sizing agent is attached to continuous reinforcing fibers, and the density D as a catalog value is a sizing agent unless otherwise specified in the catalog, for example, that the density does not include a sizing agent. Means the density as a continuous reinforcing fiber in a state where is attached. That is, if the catalog value is used as it is as the density D and is described as the density of the continuous reinforcing fiber in a state not containing the sizing agent, the value is set as the density D and the continuous reinforcing fiber in the state containing the sizing agent. The density is described as density D.
Moreover, in a present Example, about the evaluation method and measurement method regarding a continuous reinforcing fiber, the value in the state to which the sizing agent was adhered may be sufficient.
From the value of the single yarn diameter R obtained above, the ratio of the product RD of the single yarn diameter R (μm) and the density D (g / cm ³ ), the product RD of the continuous reinforcing fiber and the continuous thermoplastic resin fiber “RD ( Continuous reinforcement fiber) / RD (continuous thermoplastic resin fiber) "was further calculated.

(2) Interfacial adhesive strength by microdroplet test Interfacial adhesive strength was measured by a microdroplet test using a composite material interface property evaluation apparatus HM410 (manufactured by Toei Sangyo Co., Ltd.).
A single yarn was taken out from the continuous reinforcing fiber and set in a composite material interface property evaluation apparatus. A drop in which a thermoplastic resin as a raw material for continuous thermoplastic resin fibers was melted on the apparatus was formed on a continuous reinforcing fiber single yarn and cooled sufficiently at room temperature to obtain a sample for measurement. Set the measurement sample in the device again, sandwich the drop with the device blade, run the continuous reinforcing fiber single yarn on the device at a speed of 0.06 mm / min, and measure the maximum pulling load f (N) when pulling out the drop The interfacial bond strength τ was calculated from the following formula (2).
Interfacial adhesive strength τ = f / π · R · l (2)
(F: maximum pulling load (N), R: continuous reinforcing fiber single yarn diameter (m), l: particle diameter in the pulling direction of the drop (m))

(3) Bending elastic modulus of hollow molded body The bending elastic modulus (MPa) of the straight part of the hollow molded body was measured under the following conditions based on ISO178.
4-point bending test and test environment: 23 ° C, 50RH%
・ Distance between fulcrums 300mm
・ Distance between load points: 100mm
・ Test speed 2mm / min
-Equipment used: Instron 50kN (Instron)
The bending elastic modulus of the straight part of the hollow molded body was obtained by averaging the measured values at five locations.

(4) Formation of bent portion of hollow molded body Regarding the formation of the bent portion of the hollow molded body, the cross-section inner diameter of the bent portion (the central portion of the bend) is short with respect to the short inner radius C1 of the straight section of the bent tube. Evaluation was made based on the ratio of the shaft radius C2 ((C2 / C1) × 100) (%). The evaluation criteria are as follows.
<Evaluation criteria>
◎ (Excellent): The ratio of the short-diameter radius C2 of the cross-sectional inner diameter to the short-axis radius C1 of the straight section is 53 to 100%, and a bent portion with little change in the inner diameter and the hollow space could be formed. . In addition, there is no breakage of the continuous reinforcing fiber.
○ (Good): The ratio of the short-axis radius C2 of the cross-sectional inner diameter of the bent portion to the short-axis radius C1 of the straight section was 53 to 100%, and a bent portion with little change in the inner diameter and hollow space could be formed. . In some cases, there is breakage of continuous reinforcing fibers.
Δ (possible): The ratio of the short-axis radius C2 of the section of the bent portion to the short-axis radius C1 of the straight section is 3% or more and less than 53%. A bent portion with a space remaining could be formed.
X (not possible): The ratio of the short-diameter radius C2 of the cross-sectional inner diameter of the bent portion to the short-axis radius C1 of the straight section is less than 0 to 3%, and the hollow space is almost empty due to the collapse of the inner diameter or the breakage of continuous reinforcing fibers The bent portion could not be formed.

[Example 1]
Two bundles of glass fibers to which 1.0% by mass of sizing agent A are adhered and two bundles of polyamide 66 fibers are combined, aligned, and then supplied substantially vertically to a fluid entanglement nozzle. Thus, a composite yarn (glass fiber content: 60%, polyamide 66 fiber content: 40%) was obtained.
Fluid entangling nozzle: Kyocera KC-AJI-L (1.5 mm diameter, propulsion type)
・ Air pressure: 2kg / cm ²
・ Processing speed: 30 m / min Three composite yarns obtained above are aligned and used as a braided yarn, and are made into a braided braid by using an 8-stroke tubular braiding machine with an inner diameter of 15 mm and a braiding angle of 30 °. Obtained.
Subsequently, a hollow pipe was obtained by pultrusion molding. In the pultrusion molding, the braid was inserted into a preheating mold having an inner diameter of 18 mm, a clearance of 0.1 mm, and a temperature of 290 ° C. while being pulled, and the braid was moved at a drawing speed of 150 mm / min to melt the polyamide 66 fibers in the braid. After that, it is continuously inserted into a molding die having an inner diameter of 18 mm, a clearance of 1.5 mm, and a temperature of 50 ° C., and the braid is moved at the same drawing speed of 150 mm / min. A cylindrical body having an outer diameter of 18 mm, an inner diameter of 15 mm, a thickness of 1.5 mm, and a length of 2 mm was obtained.
A core wire was inserted into the obtained cylinder, and the cylinder was heated to about 280 ° C. using an IR heater. Using a pipe bender that has been heated to 200 ° C in advance at the part that comes into contact with the cylinder by scoring with a burner, the cylinder is bent at an angle of 30 ° with 100mm from the end of the cylinder as the center of the corner. A hollow molded body having a part was obtained.
Table 1 shows the physical properties of Example 1.

[Examples 2 to 5]
In Examples 2 to 5, hollow molded bodies having bent portions were produced in the same manner as in Example 1 except that the raw material composition and production conditions were changed as shown in Table 1.
The physical properties of Examples 2 to 5 are shown in Table 1.

[Comparative Example 1]
In Comparative Example 1, a hollow molded body was produced in the same manner as in Example 1 except that the cylindrical body was bent manually without using the core wire and the pipe bender.
Table 1 shows the physical properties of Comparative Example 1.

[Comparative Example 2]
A braid is produced with a yarn consisting only of glass fibers to which the sizing agent A is attached in an amount of 1.0% by mass, and the resulting braid is impregnated with an epoxy resin (glass fiber content: 60%, epoxy resin content: 40%), a hollow molded body was produced in the same manner as in Example 1 except that the pultrusion molding was performed.
Table 1 shows the physical properties of Comparative Example 2.

[Comparative Example 3]
In Comparative Example 3, a hollow molded article was produced in the same manner as in Comparative Example 1 except that the raw material composition, production conditions and the like were changed as shown in Table 1.
Table 1 shows the physical properties of Comparative Example 3.

  Since the hollow molded body of the present invention has high strength excellent in bending workability, it has a complicated shape and is used in various machines, automobiles, and appliances that require high-level mechanical properties. It can be suitably used as a hollow machine part and structure.

Claims (12)

  A hollow molded article having a bent portion, comprising a thermoplastic resin and continuous reinforcing fibers.   The hollow molded body according to claim 1, wherein the continuous reinforcing fibers are braided.   The thermoplastic resin is selected from the group consisting of polyolefin resin, polyamide resin, polyester resin, polyether ketone, polyether ether ketone, polyether sulfone, polyphenylene sulfide, thermoplastic polyetherimide, and thermoplastic fluorine resin. The hollow molded body according to claim 1 or 2, which is at least one selected.   The continuous reinforcing fiber is at least one selected from the group consisting of glass fiber, carbon fiber, aramid fiber, ultra high strength polyethylene fiber, polybenzazole fiber, liquid crystal polyester fiber, polyketone fiber, metal fiber, and ceramic fiber. The hollow molded object according to any one of claims 1 to 3.   The hollow molded body according to any one of claims 1 to 4, wherein the content of the continuous reinforcing fibers is 30% by mass or more.   The method for producing a hollow molded body according to any one of claims 1 to 5, wherein a cylindrical body including a thermoplastic resin and continuous reinforcing fibers is used.   The manufacturing method of the hollow molded object of Claim 6 using the braid containing a thermoplastic resin fiber and a continuous reinforcement fiber.   The manufacturing method of the hollow molded object of Claim 6 or 7 which further includes the process of bending the said cylinder.   The method for producing a hollow molded body according to claim 8, wherein the step of bending the cylindrical body includes a step of bending the cylindrical body using a bending machine.   The method for producing a hollow molded body according to claim 8 or 9, wherein the step of bending the cylindrical body includes a step of heat-softening the cylindrical body.   The manufacturing method of the hollow molded object as described in any one of Claims 8-10 including the process of inserting a center core inside the said cylinder.   The manufacturing method of the hollow molded object as described in any one of Claims 9-11 including the process of previously warming the part which contacts the said cylinder of the said bending machine.