Composite wire and method for producing the same

Abstract

To provide a composite wire and its production method, the composite wire being applicable to diverse uses and having characteristics such as elasticity.SOLUTION: A composite wire 1 comprises an outer tube 2 and a foamed strip 3, the outer tube 2 being formed of a thermoplastic resin. The foamed strip 3, made of thermoplastic resin in a foamed state, is arranged in a helical form inside the outer tube 2, with the foamed strip 3 having an outer surface 3a that is partly in contact with an inner wall 2a of the outer tube 2. The composite wire 1 is manufactured by extrusion molding, in which the outer tube 2 and the foamed strip 3 are simultaneously extruded, and the extrusion speed of the foamed strip 3 is set to be higher than that of the outer tube 2, so that part of the foamed strip 3 is helically disposed inside the outer tube 2.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a composite wire made of synthetic resin that can be used for various applications and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a flexible fibrous linear body having a core string and a sheath string covering the core string on the outside.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although this fibrous linear body can be used for various applications, its stretchability in the longitudinal direction is not sufficient.

[0005] An object of the present invention is to provide a composite wire that can be used for various applications and has stretchability and the like, and a method for manufacturing the same.

Means for Solving the Problems

[0006] The composite wire according to the present invention for achieving the above object is composed of a flexible member including an outer cylindrical body made of a thermoplastic resin and a strip made of a thermoplastic resin formed in a spiral shape inside the outer cylindrical body with a part of the outer surface in contact with the inner wall of the outer cylindrical body.

[0007] In addition, the method for manufacturing a composite wire according to the present invention includes extruding a softened or melted thermoplastic resin material from an annular hole at a first extrusion speed to continuously form the outer cylindrical body, and simultaneously and in parallel, extruding and foaming a softened or melted thermoplastic resin material from a small hole disposed at a position eccentric from the central position in the region surrounded by the annular hole at a second extrusion speed greater than the first extrusion speed; and a step of continuously forming the strip by spirally arranging a part of the side surface of the thermoplastic resin material extruded at the second extrusion speed inside the outer cylindrical body while bringing it into contact with the inner wall of the outer cylindrical body continuously formed by extrusion at the first extrusion speed.

Advantages of the Invention

[0008] According to the composite wire according to the present invention, by providing a strip spirally arranged inside the outer cylindrical body, when pressure is applied in the stretching direction and the compression direction, an appropriate repulsive force can be obtained, and a wire excellent in stretchability can be obtained.

[0009] Furthermore, when touching the outer cylindrical portion on the outside, a feeling as if the uneven shape is continuous due to the internal spiral foamed strip can be obtained. Due to this uneven shape, for example, when used as a shoelace material, the lacing material can be made such that the uneven portions are hooked on each other and difficult to untie.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

Example

[0012] FIG. 1 is a cross-sectional view of the composite wire of Example 1, and FIG. 2 is a perspective view of the composite wire. The composite wire 1 is made of a flexible synthetic resin and is composed of an outer cylindrical body 2 and a foamed strip 3. In this composite wire 1, the outer cylindrical body 2 is arranged on the outside, and the foamed strip 3 is spirally arranged inside the outer cylindrical body 2, and a part of the outer surface 3a of the foamed strip 3 is in contact with the inner wall 2a of the outer cylindrical body 2.

[0013] The outer cylindrical body 2 can also be foamed in the same manner as the foamed strip 3. Furthermore, the strip spirally arranged inside the outer cylindrical body 2 does not necessarily have to be foamed. By foaming the outer cylindrical body 2, weight reduction can be achieved, but the strength decreases. Also, when the strip spirally arranged inside is not foamed, the repulsive force when pressure is applied from the outside is lower than that of the foamed strip 3.

[0014] During the extrusion molding of the composite wire 1 including the foamed strip 3 described later, due to the internal pressure generated by the foaming of the foaming agent contained in the foamed strip 3 inside the outer cylindrical body 2, the cross-section of the outer cylindrical body 2 solidifies in a circular shape as shown in the figure. On the other hand, during the extrusion molding of the composite wire 1 including a non-foamed strip, since the internal pressure does not increase during foaming, the cross-section 2b of the outer cylindrical body 2 collapses due to its own weight and solidifies in an elliptical and flattened shape.

[0015] The outer cylinder 2 extends linearly and long, and its outer side is an outer wall 2c, and it has an inner wall 2a on the inner side thereof. The portion where a part of the outer surface 3a of the foamed strip 3 is in contact with the inner wall 2a of the outer cylinder 2 maintains the contact state by adhesion during solidification. Note that a part of the outer surface 3a of the foamed strip 3 may be maintained in contact with the inner wall 2a of the outer cylinder 2 by frictional resistance. Also, the direction in which the composite wire 1 extends long is defined as the axial direction, and the direction orthogonal thereto is defined as the radial direction. Also, the outer cylinder 2 and the foamed strip 3 shall also be according to this example.

[0016] The outer cylinder 2 is made of a thermoplastic resin, the shape of the outer cylinder 2 is cylindrical, both ends are open, its interior is hollow, and the openings at both ends communicate with each other. When the outer cylinder 2 is cut by a plane orthogonal to the linear direction in which the composite wire 1 extends, the shape of the cross-section 2b thereof is annular.

[0017] The outer cylinder 2 extends linearly and long, and has an outer wall 2c on the outer side thereof and an inner wall 2a on the inner side thereof. The outer diameter of the outer cylinder 2, that is, the outer diameter of the outer wall 2c, is, for example, 1 to 20 mm, and the inner diameter of the outer cylinder 2, that is, the inner diameter of the inner wall 2a, is, for example, 0.8 to 18 mm. Also, the thickness of the cross-section 2b of the outer cylinder 2 is, for example, 0.1 to 1 mm.

[0018] The thermoplastic resin material for producing the outer cylinder 2 may be any material that can be softened or melted by heating to enable easy extrusion molding. Examples of such thermoplastic resin materials include polyethylene, polypropylene, crystalline polyethylene terephthalate and other crystalline thermoplastic resins, polyvinyl chloride, polystyrene, amorphous polyethylene terephthalate and other amorphous thermoplastic resins, and thermoplastic elastomers, etc. Among them, thermoplastic elastomers are particularly preferred.

[0019] The foamed strip 3 shown in FIGS. 1 and 2 is made of a thermoplastic resin in a foamed state and extends spirally along the axial direction. The interior of the foamed strip 3 is dense except for the bubble portions generated by foaming.

[0020] When the foamed strip 3 is cut in the radial direction orthogonal to the axial direction in which the composite wire 1 extends, its cross section 3b has an elliptical shape. The outer diameter of the foamed strip 3, that is, the outer diameter of the outer surface 3a, is preferably 1 / 3 or more of the inner diameter of the outer cylindrical body 2, for example, 0.3 to 6 mm.

[0021] The thermoplastic resin material for forming the foamed strip 3 may be any material that can be softened or melted by heating to enable easy extrusion molding and can be extruded and foamed at the same time. As such a thermoplastic resin material, similar to the outer cylindrical body 2, for example, polyethylene, polypropylene, crystalline polyethylene terephthalate and other crystalline thermoplastic resins, polyvinyl chloride, polystyrene, amorphous polyethylene terephthalate and other amorphous thermoplastic resins, and thermoplastic elastomers, etc. can be mentioned, and thermoplastic elastomers are particularly preferred.

[0022] When foaming the thermoplastic resin material, the mode of the bubbles generated by the foaming may be either single bubbles or continuous bubbles.

[0023] The composite wire 1 can be manufactured by extrusion molding. FIG. 3 is a front view of the mold K used when performing extrusion molding, FIG. 4 is a perspective view of the mold K, FIG. 5 is an explanatory view of the state in which the composite wire 1 is extruded from the mold K, and FIG. 6 is a cross-sectional view of the composite wire 1 and the mold K when the composite wire 1 extruded from the mold K is bisected along the axial direction. Note that the outer shape of the mold K is substantially rectangular, but an appropriate shape can be adopted.

[0024] When manufacturing the composite wire 1, the outer cylindrical body 2 and the foamed strip 3 are simultaneously extrusion molded, and while performing their respective molding, the outer cylindrical body 2 and the foamed strip 3 are arranged so as to form a predetermined relationship, whereby the composite wire 1 can be generated at once.

[0025] The thermoplastic resins that are the raw materials for the outer cylindrical body 2 and the foamed strip 3 are as described above. However, the outer cylindrical body 2 and the foamed strip 3 may be made of the same thermoplastic resin, may be made of thermoplastic resins of the same type but with different molecular weights and / or densities, or may use different types of thermoplastic resins as raw materials.

[0026] The mold K shown in FIGS. 3 and 4 has, as a first extrusion port, an annular hole K1 for extruding a thermoplastic resin material to form the outer cylindrical body 2, and, as a second extrusion port, a pore K2 for extruding the pre-foamed thermoplastic resin to form the foamed strip 3.

[0027] The annular hole K1 is a first extrusion port composed of an annular through-hole. By extruding the softened or melted thermoplastic resin material from here, the outer cylindrical body 2 having an annular cross-section is continuously formed. Note that the outer diameter and inner diameter of the annular hole K1 shall be adapted to the outer diameter and inner diameter of the outer cylindrical body 2 to be formed.

[0028] The mold K includes a peripheral portion surrounding the annular hole K1 from the outside and a central portion inside the annular hole K1, respectively. Further, a pore K2 is provided in the central portion.

[0029] The pore K2 is a second extrusion port for continuously forming a strip having a circular cross-sectional shape by extruding the softened or melted pre-foamed thermoplastic resin material. The pore K2 is composed of a through-hole with a smaller diameter than the annular hole K1 and is eccentrically arranged in the central portion inside the annular hole K1. That is, the pore K2 is arranged at a position other than the center position K3 of the annular hole K1. In the mold K shown in FIGS. 3 and 4, the pore K2 is located slightly to the left of the center position K3, but it may also be on the lower side or the like.

[0030] Thus, by providing the pore K2 at a position eccentric from the central position K3, it becomes possible to efficiently form the foamed strip 3 in a spiral shape. Further, the outer diameter of the pore K2 is made smaller than the outer diameter of the foamed strip 3 to be formed. This is because when the thermoplastic resin material is foamed, bubbles are generated and expand, resulting in an increase in its outer diameter compared to before foaming.

[0031] In the process of extruding the composite wire 1, first, the thermoplastic resin material for forming the outer cylinder 2 is pre-heated to be softened or melted. Similarly, the thermoplastic resin material before foaming for forming the foamed strip 3 is also pre-heated to be softened or melted.

[0032] Subsequently, the softened or melted thermoplastic resin material is extruded from the annular hole K1 at the first extrusion speed. As a result, as shown in FIG. 5, the outer cylinder 2 is continuously extruded with an annular cross-sectional shape.

[0033] In parallel with the extrusion of the outer cylinder 2, the thermoplastic resin material before foaming softened or melted from the pore K2 is extruded at a second extrusion speed greater than the first extrusion speed to be foamed, and the foamed strip 3 is extruded. In this foaming, for example, after dissolving nitrogen gas or carbon dioxide gas, which is a foaming agent, and the thermoplastic resin material under high pressure, it is extruded from the pore K2, and bubbles are generated due to a pressure drop to form a foam. In addition to such physical foaming, an appropriate foaming method such as chemical foaming can be adopted for foaming.

[0034] Subsequently, the first and second extrusion speeds will be described. The extrusion speed is the speed at which the extruded thermoplastic resin material advances, and specifically, it refers to the distance traveled by the extruded outer cylinder 2 per unit time.

[0035] The first extrusion speed is preferably, for example, 1 to 20 m / min. Also, the second extrusion speed is greater than the first extrusion speed, preferably, for example, 1.5 to 5 times the first extrusion speed, and more preferably approximately 2 times the first extrusion speed. Accordingly, the second extrusion speed is preferably 2 to 40 m / min.

[0036] Here, taking as an example the case where the second extrusion speed is twice the first extrusion speed, if the path traveled by the outer cylinder 2 per unit time in the process from the softened or melted state to the cooled and solidified state is taken as 1, then the path traveled by the foamed strip 3 or its precursor in the softened or melted state per unit time in the process from the softened or melted state to the cooled and solidified state is 2.

[0037] That is, the outer cylinder 2 extruded at the first extrusion speed travels along a straight line or a gentle curve, while the foamed strip 3 extruded at the greater second extrusion speed travels spirally inside the outer cylinder 2. For this reason, despite the difference between the first extrusion speed and the second extrusion speed of the outer cylinder 2 and the foamed strip 3, that is, the difference in the path traveled per unit time for each, the traveling distances of each, that is, the straight-line distances from the first and second extrusion ports, are substantially equal.

[0038] These first and second extrusion speeds can be controlled by adjusting the extrusion pressure, and in the case of the outer cylinder 2, by also adjusting the take-up speed.

[0039] As shown in FIGS. 5 and 6, while the outer cylinder 2 is being extruded, the foamed strip 3 is continuously extruded and arranged spirally inside the outer cylinder 2. Note that the shape of the cross-section 3c of the foamed strip 3 when bisected along the longitudinal direction of the extruded composite wire 1 is substantially circular as shown in FIG. 6, and the outer diameter of this cross-section 3c is 1 / 3 or more of the inner diameter of the outer cylinder 2, for example, 0.3 to 6 mm.

[0040] As described above, the extruded outer cylinder 2 and the foamed strip 3 are extruded such that the paths they travel per unit time are different from each other. And the extruded foamed strip 3 will eventually have a part of its side surface abut against the inner wall 2a of the outer cylinder 2.

[0041] That is, a part of the outer surface 3a of the foamed strip 3 immediately after extrusion abuts against the inner wall 2a of the outer cylinder 2, and the abutted portion is welded. Since the foamed strip 3 with the welded abutting portion is extruded with a length per unit time longer than the length that the outer cylinder 2 travels due to the difference between the first and second extrusion speeds, it cannot travel linearly inside the outer cylinder 2 as it is. On the other hand, new foamed strips 3 will continue to be extruded from the pores K2 with the same extrusion pressure. For this reason, instead of traveling linearly, the extruded foamed strip 3 will travel along the inner wall 2a of the outer cylinder 2 in a spiral manner with the point where it first abutted against the inner wall 2a of the outer cylinder 2 as the starting point. In this way, by making the second extrusion speed of the foamed strip 3 faster than the first extrusion speed of the outer cylinder 2, a part of the foamed strip 3 will be arranged while being spirally welded to the inside of the outer cylinder 2.

[0042] Note that the extruded and foamed foamed strip 3 generates an internal pressure that keeps the cross-section of the outer cylinder 2 circular due to the generated gas, is cooled over time, and solidifies in the state of the composite wire 1 shown in Fig. 2. Also, air holes for discharging air may be provided at the center of the mold K to keep the cross-section of the outer cylinder 2 circular.

[0043] Furthermore, when touching the outer wall 2c of the outer cylinder 2 by hand, a feeling as if the concave and convex shapes are continuous due to the internal spiral foamed strip 3 can be obtained. Due to this concave and convex shape, for example, when used as a shoelace material, the concave and convex portions of the outer wall 2c of the outer cylinder 2 can be made into a shoelace material that is difficult to untie because the concave and convex portions catch on each other.

[0044] Particularly, in the case of the composite wire 1 in which the strip material spirally arranged inside the outer cylinder 2 is not foamed, as described above, the cross-section of the outer cylinder 2 collapses due to its own weight and becomes an elliptical and flattened shape. Therefore, by using the composite wire 1 in which the strip material is not foamed instead of the shoelace of a sneaker having a rectangular cross-section, it becomes difficult to become entangled and untie, and it also becomes excellent in terms of design.

Example

[0045] FIG. 7 is a perspective view of the composite wire 1' of Example 2. This composite wire 1' is also composed of a flexible member including an outer cylinder 2 and a foamed strip 3, similar to the composite wire 1, and has a chip shape obtained by cutting the continuous flexible member into small pieces, for example, at intervals of 1 to 2 cm.

[0046] The composite wire 1' has a pair of end portions 1a and 1b existing on both sides at a predetermined interval, and one end face 3d of the foamed strip 3 appears at the end portion 1a of the composite wire 1'. Further, the other end face 3e of the foamed strip 3 appears from the end portion 1b of the composite wire 1'. In this case, with respect to one end face 3d of the foamed strip 3 exposed from one end portion 1a, the other end face 3e of the foamed strip 3 exposed from the other end portion 1b is in a position where the foamed strip 3 has undergone a displacement of one or more rotations.

[0047] In FIG. 7, one end face 3d and the other end face 3e of the foamed strip 3 are in the same or substantially the same position after undergoing a displacement of one rotation, but it may be more than one rotation.

[0048] From the above, the center point 3f of the foamed strip 3 between the end portions 1a and 1b rotates at least 360° or more, that is, one or more rotations, with the central axis of the outer cylinder 2 as the rotation axis.

[0049] FIG. 8 is an explanatory view showing the cutting process of the flexible member extruded from the mold. By cutting the flexible member composed of the continuously formed outer cylinder 2 and the foamed strip 3 at a predetermined interval, for example, by a cutter C, the chip-shaped composite wire 1' shown in FIG. 7 can be obtained.

[0050] In this way, by adopting the foamed strip 3 in the composite wire 1' having a spiral shape with a rotation speed of one rotation or more, the chip-shaped composite wire 1' generates an equal repulsive force against the pressure from its surroundings by itself. Also, by using a large number of composite wires 1' simultaneously, the repulsive forces of the respective composite wires 1' act on each other, and the repulsive force can be made more uniform.

[0051] Utilizing this property, the chip-shaped composite wire 1' can be filled inside bedding such as pillows, cushions, and mats and used as a cushioning material. A large number of chip-shaped composite wires 1' having low resilience are arranged in all loose directions of up, down, left, and right inside the bedding, so that the elastic force acts evenly without bias, and the user's feeling of using the bedding can be enhanced.

[0052] Furthermore, in the chip-shaped composite wire 1', when the outer cylinder 2 is also foamed, when it is filled inside bedding such as pillows, cushions, and mats, even if the composite wires 1' collide with each other, no fine collision sound will occur. In particular, when a general cushioning material is used for a pillow, even if the collision sound generated from the cushioning material is fine, it is generated near the ear, which may bother sensitive users. However, when the composite wire 1' with the foamed outer cylinder 2 is used as a cushioning material, no collision sound will occur, so that even sensitive users can obtain a comfortable sleep.

[0053] In this way, according to the composite wires 1 and 1' according to the present invention, by providing the strip arranged spirally inside the outer cylinder 2, when pressure is applied in the axial direction and the radial direction, an appropriate repulsive force can be obtained, and a wire excellent in elasticity can be obtained.

[0054] The operational effects achieved by such the present invention are brought about for the first time because the strip arranged inside the outer cylinder 2 is formed in a spiral shape. And the composite wires 1 and 1' having such a structure do not exist conventionally and are materials applicable to uses other than the above-described uses.

Explanation of Reference Numerals

[0055] 1. 1’ Composite wire 1a One end 1b The other end 1c First virtual plane 1d Second virtual plane 2 Outer cylinder 2a Inner wall 2b Cross-section 2c Outer wall 3 Foamed strip 3a Outer surface 3d One end face 3e The other end face 3f Center point K Mold K1 Annular hole K2 Pore K3 Center position

Claims

1. A composite wire characterized by being composed of a flexible member including an outer cylindrical body made of a thermoplastic resin and a strip made of a thermoplastic resin formed in a spiral shape inside the outer cylindrical body with a part of the outer surface in contact with the inner wall of the outer cylindrical body.

2. The composite wire according to claim 1, wherein the strip is a foamed strip obtained by foaming a softened or melted thermoplastic resin material.

3. The composite wire according to claim 2, wherein the outer diameter of the strip is 1 / 3 or more of the inner diameter of the outer cylindrical body.

4. The composite wire according to claim 2 or 3, wherein the portion where a part of the outer surface of the foamed strip is in contact with the inner wall of the outer cylindrical body is maintained in a contact state by welding.

5. The composite wire according to claim 2 or 3, wherein the foamed strip rotates at least once in a spiral shape inside the outer cylindrical body between both ends.

6. The composite wire according to claim 5, wherein the flexible member is chip-shaped.

7. A method for manufacturing a composite wire composed of a flexible member including an outer cylindrical body made of a thermoplastic resin and a strip made of a thermoplastic resin formed in a spiral shape inside the outer cylindrical body, comprising: Extruding a softened or melted thermoplastic resin material from an annular hole at a first extrusion speed to continuously form the outer cylindrical body, and at the same time and in parallel, extruding and foaming a softened or melted thermoplastic resin material from a small hole arranged at an eccentric position from the central position in the region surrounded by the annular hole at a second extrusion speed greater than the first extrusion speed; A step of continuously forming the strip by arranging a part of the side surface of the thermoplastic resin material extruded at the second extrusion speed in a spiral shape inside the outer cylindrical body while bringing it into contact with the inner wall of the outer cylindrical body continuously formed by being extruded at the first extrusion speed.

8. The method for manufacturing a composite wire according to claim 7, including a step of dissolving a foaming agent in the softened or melted thermoplastic resin material before extruding at the second extrusion speed, wherein the strip arranged in a spiral shape inside the outer cylindrical body is a foamed strip.

9. The manufacturing method of the composite wire according to claim 8, characterized in that, for the flexible member extruded and continuously formed, the foamed strip material between both end portions includes a step of cutting into chip shapes at equal intervals with a length that rotates at least once or more in a spiral shape.

10. The manufacturing method of the composite wire according to claim 8 or 9, characterized in that the outer diameter of the foamed strip material is 1 / 3 or more of the inner diameter of the outer cylindrical body.

11. The manufacturing method of the composite wire according to claim 8 or 9, characterized in that the second extrusion speed is 1.5 to 5 times the first extrusion speed.

Images