Composite injection-molded shoe and method for manufacturing same

Abstract

Provided are a composite injection-molded shoe and a method for manufacturing same. The method for manufacturing a composite injection-molded shoe comprises: i) a step of providing a midsole that has been physically foamed and injection-molded in a mold; ii) a step of inserting the midsole into another mold having an opening, so that the rear surface of the midsole is exposed upward through the opening; iii) a step of providing a coalesced sole by injecting an outsole through the opening so as to be attached to the rear surface of the midsole; and iv) a step of separating the coalesced sole from the another mold. In the step of providing a coalesced sole, liquid raw material for the outsole is pressurized to form perforations in a closed skin of the midsole that has been formed in the step of providing a midsole, penetrates into the midsole, and, by penetrating into a plurality of pores that are surrounded by the closed skin, melts the edges of the pores while being solidified.

Description

Composite injection-molded shoes and their manufacturing method

[0001] The present invention relates to composite injection-molded shoes and a method for manufacturing the same. More specifically, the present invention relates to shoes made by composite injection-molding shoe parts and a method for manufacturing the same.

[0002] Shoe manufacturing requires three main components: the upper, midsole, and outsole. The upper, the upper of the shoe, wraps and protects the instep, maintaining the shoe's external design and shape. The midsole, located between the upper and the outsole, provides cushioning. The outsole, the lowest part of the shoe and the part that touches the ground, provides anti-slip and wear protection.

[0003] Traditionally, shoes were manufactured by bonding the upper, midsole, and outsole together through separate processes. Primers or adhesives were used to bond these components together. Furthermore, to enhance the bonding strength of these components, their surfaces were modified through UV treatment or preheated in an oven. Meanwhile, to simplify the process, hot melt film was used to bond these components together.

[0004] We aim to provide shoes made by composite injection molding of shoe parts. We also aim to provide a method for manufacturing such shoes.

[0005] A method for manufacturing a composite injection-molded shoe according to one embodiment of the present invention comprises the steps of: i) providing a midsole that is physically foam-molded in a mold; ii) inserting the midsole into another mold having an opening formed therein so that the back surface of the midsole is exposed upward through the opening; iii) providing a composite sole by injecting an outsole into the opening and attaching it to the back surface of the midsole; and iv) separating the composite sole from the other mold. In the step of providing the composite sole, a raw material liquid of the outsole is pressurized to form a perforation in the closed skin of the midsole formed in the step of providing the midsole, thereby penetrating into the interior of the midsole, and solidifying by penetrating a plurality of pores surrounded by the closed skin and melting the surrounding area.

[0006] In the step of exposing the back surface of the midsole upward, another mold may include: i) a left mold portion, and ii) a right mold portion that is separable laterally from the left mold portion. The left mold portion and the right mold portion may be joined to each other in the width direction to form an opening. The depth of the opening may be greater than the average thickness of the midsole.

[0007] In the step of providing the midsole, the midsole may be manufactured from one or more resins selected from the group consisting of thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), thermoplastic copolyester elastomer (TPC-ET), polyether block amide (PEBA), polycarbonate (PC), and styrene-ethylene-butylene-styrene (SEBS). In the step of providing a composite sole, the outsole may be made of one or more resins selected from the group consisting of TPEE (Thermoplastic Polyester Elastomer), Thermoplastic Elastomer (TPE), PEBA (Polyether Block Amide), TPU (Thermoplastic Polyurethane), TPV (Thermoplastic Vulcanizates), and EVA (Ethylene-Vinyl Acetate).

[0008] In the step of exposing the back surface of the midsole, the back surface may be surface-treated to increase its surface roughness. The surface roughness may be 10 μm to 1000 μm. In the step of exposing the back surface of the midsole, the back surface may be etched to form a plurality of protrusions on the back surface. In the step of providing the midsole, the mold may include an upper mold portion and a lower mold portion, and the upper mold portion and the lower mold portion may be joined to form a hollow space. The step of providing the midsole may include the steps of: i) providing a mixture in which a supercritical fluid is mixed with a melt; ii) pressurizing the hollow space by introducing a gas; iii) foaming the mixture in the hollow space while injecting the mixture into the hollow space; iv) multi-stage depressurizing the hollow space after injecting the mixture; and v) separating the upper mold portion and the lower mold portion from each other to remove the foamed midsole. In the step of foaming the mixture, the lower mold portion may be formed with an intake / exhaust passage surrounding the hollow space. The vertical length of the hollow space is greater than the horizontal length of the hollow space intersecting the vertical direction at right angles, and a plurality of intake and exhaust holes are formed in each of the intake and exhaust passages located at both ends of the vertical direction, and the plurality of intake and exhaust holes can be connected to the hollow space. The injection speed of the mixture in the step of foaming the mixture and the decompression speed of the hollow space in the step of multi-stage decompression of the hollow space can be substantially the same.

[0009] In the step of exposing the back surface of the midsole to the upper side through the opening, the area of ​​the opening in contact with the lower surface of another mold may be larger than the planar area of ​​the midsole. Among the areas of the opening, the area not shared with the planar area of ​​the midsole may surround the planar area of ​​the midsole.

[0010] A method for manufacturing a composite injection-molded shoe according to another embodiment of the present invention comprises the steps of: i) providing an upper including a sole; ii) fixing the upper to a mold while covering an opening formed in the mold with the sole; iii) providing a composite sole by physically foam-molding a midsole into the mold to attach the sole to the midsole; and iv) removing the composite sole from the mold. In the step of providing the upper, the upper comprises: i) a plurality of yarn bundles, and ii) a plurality of polymer strings intertwined with the plurality of yarn bundles.

[0011] A plurality of yarn bundles are arranged in parallel and spaced apart from each other, and a plurality of polymer strings intersect with the plurality of yarn bundles and may alternately pass through the upper and lower portions of the plurality of yarn bundles, respectively. An average width of the plurality of yarn bundles may be greater than an average width of the plurality of polymer strings. The plurality of polymer strings may include a pair of polymer strings that are intertwined with each other, and a pair of polymer strings may be positioned above and below each other, with two or more yarn bundles of the plurality of yarn bundles positioned between them. In the step of providing the upper, the upper may be formed by intermixing the yarn and the polymer through electrospinning.

[0012] In the step of providing a combined sole, the mold may include an upper mold portion and a lower mold portion, and the upper mold portion and the lower mold portion may be combined to form a hollow space. The physical foaming injection of the midsole into the mold may include the steps of: i) providing a mixture in which a supercritical fluid is mixed with a melt; ii) pressurizing the hollow space by introducing gas into the hollow space; iii) foaming the mixture in the hollow space while injecting the mixture into the hollow space; iv) depressurizing the hollow space in multiple stages after the injection of the mixture; and v) separating the upper mold portion and the lower mold portion from each other to take out the foamed midsole.

[0013] In the step of foaming the mixture, an intake / exhaust passage surrounding a hollow space may be formed in the lower mold portion. The vertical length of the hollow space is greater than the horizontal length of the hollow space intersecting the vertical direction at a right angle, and a plurality of intake / exhaust holes are formed in each of the intake / exhaust passages located at both ends in the vertical direction, and the plurality of intake / exhaust holes may be in communication with the hollow space. The injection speed of the mixture in the step of foaming the mixture and the decompression speed of the hollow space in the step of multi-stage decompression of the hollow space may be substantially the same.

[0014] In the step of providing the combined sole, the injection speed of the raw material for the outsole may be 30 mm / sec to 200 mm / sec. In the step of providing the combined sole, the injection pressure of the raw material for the outsole may be 30 MPa to 300 MPa. In the step of providing the combined sole, the injection temperature of the raw material for the outsole may be 100°C to 250°C.

[0015] According to one embodiment of the present invention, a composite injection-molded shoe comprises: i) an upper including a sole; and ii) a midsole attached to the sole. The upper comprises: i) a plurality of yarn bundles arranged in parallel and spaced apart from each other; and ii) a plurality of polymer strings intertwined with the plurality of yarn bundles while intersecting the plurality of yarn bundles and alternately passing over and under the plurality of yarn bundles, respectively. An average width of the plurality of yarn bundles is greater than an average width of the plurality of polymer strings. The plurality of polymer strings comprises a pair of polymer strings that are intertwined, and the pair of polymer strings are positioned one above the other and two or more yarn bundles of the plurality of yarn bundles are positioned between the pair of polymer strings.

[0016] The shoe manufacturing process can be simplified by simultaneously molding the upper, midsole, and outsole. Furthermore, the upper and midsole, or the midsole and outsole, can be molded simultaneously. This significantly reduces shoe manufacturing costs and time. Furthermore, the shoe's recyclability can be increased. Additional processes, such as the use of adhesive chemicals and four-way pressing, are unnecessary. Consequently, the upper, midsole, and outsole can be uniformly and strongly bonded together, resulting in composite injection-molded shoes with enhanced adhesion.

[0017] FIG. 1 is a schematic flowchart of a method for manufacturing a composite injection shoe according to a first embodiment of the present invention.

[0018] Figures 2 to 8 are schematic drawings showing each step of the manufacturing method of the composite injection shoe of Figure 1.

[0019] Figure 9 is a schematic flowchart of a method for manufacturing a composite injection shoe according to a second embodiment of the present invention.

[0020] Figures 10 to 14 are schematic drawings showing each step of the manufacturing method of the composite injection shoe of Figure 8.

[0021] Figures 15 to 17 are photographs according to Experimental Example 1 of the present invention.

[0022] Figures 18 and 19 are photographs according to Experimental Example 3 of the present invention.

[0023] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising," as used herein, specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, components, and / or groups.

[0024] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0025] The term "composite foam injection molded article" used below refers to a component with multiple pores formed within it through a foaming process. Furthermore, "foaming" is interpreted to include both physical and chemical foaming.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0027] Figure 1 schematically illustrates a flowchart of a method for manufacturing composite injection-molded shoes according to a first embodiment of the present invention. The method for manufacturing composite injection-molded shoes of Figure 1 is merely illustrative of the present invention and is not intended to limit the present invention. Accordingly, the method for manufacturing composite injection-molded shoes can be modified into other forms.

[0028] As illustrated in Fig. 1, the method for manufacturing composite injection-molded shoes includes a step (S10) of providing a midsole that has been physically foam-molded from a mold, a step (S20) of inserting the midsole into another mold having an opening formed therein so that the back surface of the midsole is exposed upward through the opening, a step (S30) of providing a composite sole by injecting an outsole into the opening and attaching it to the back surface of the midsole, and a step (S40) of separating the composite sole from the other mold. In addition, the method for manufacturing composite injection-molded shoes may further include other steps.

[0029] First, in step (S10), a midsole is provided by physical foam injection molding from a mold. The manufacturing process of this midsole is described in more detail below with reference to FIGS. 2 to 4.

[0030] Figure 2 schematically illustrates the side structure of the mold (50) used in step (S10). The structure of the mold (50) in Figure 2 is merely illustrative of the present invention, and the present invention is not limited thereto. Accordingly, the structure of the mold (50) can be modified into other forms.

[0031] As illustrated in Fig. 2, the mold (50) includes an upper mold portion (501) and a lower mold portion (503), which are cores. The upper mold portion (501) and the lower mold portion (503) are stably placed and positioned within an upper support (511) and a lower support (513), respectively. The lower support portion (513) can move up and down in the direction of the arrow, i.e., the z-axis direction.

[0032] The mold (50) is preheated to 10°C to 80°C to efficiently foam the mixture (M) of resin and physical foam as the raw material of the midsole. If the heating temperature of the mold (50) is too low, it is not desirable for the foaming of the mixture (M). And if the heating temperature of the mold (50) is too high, the mixture (M) may be overheated and the lead time may be prolonged. Therefore, the heating temperature of the mold (50) is maintained within the aforementioned range. Meanwhile, by setting the temperature of the mold (50) to room temperature or lower, the surface of the foam can be improved or the thickness of the closed skin layer formed on the surface can be controlled. Meanwhile, thermoplastic elastomer (TPE), thermoplastic polyurethane (TPU), thermoplastic copolyester elastomer (TPC-ET), polyether block amide (PEBA), polycarbonate (PC), or styrene-ethylene-butylene-styrene (SEBS) can be used as the resin. Nitrogen or carbon dioxide can be used as the physical foaming agent.

[0033] Injection gates (505) are attached to the upper mold part (501). The mixture (M) flowing in the direction of the arrow is injected into the hollow space (S50) through the injection gates (505) to foam. The injection gates (505) are arranged along the y-axis direction, i.e., the vertical length direction of the hollow space (S50). Since the midsole is formed in a shape that extends in the y-axis direction, three injection gates (505) must be arranged in the y-axis direction to quickly manufacture the midsole. Among the injection gates (505), there may be one or more time zones in which the step of injecting the mixture (M) and the step of delaying the injection of the mixture (M) are performed differently for each injection gate (505). For example, multi-stage injection is possible by adjusting the delay time and the operation time of each injection gate (505). As a result, multi-stage injection using the injection gate (505) is possible, so that a low-density member with uniform foaming can be manufactured.

[0034] A hollow space (S50) for foam injection of a midsole is formed in the lower mold section (503). A mixture (M) is injected through an injection gate (505) arranged along the y-axis direction, and gas is sucked in or exhausted through an intake or exhaust pipe (5011). The mold (50) can be operated by a hydraulic system, an electric system, or a hybrid hydraulic / electric system.

[0035] Fig. 3 schematically illustrates a state in which gas is sucked into a hollow space (S50) formed by combining an upper mold part and a lower mold part to pressurize the hollow space. Fig. 3 illustrates the upper plane of the lower mold (503) of Fig. 2, that is, the state as viewed from above in the xy plane direction, rotated 90° for convenience. In Fig. 3, the horizontal length means the length in the direction parallel to the x-axis, and the vertical length means the length in the direction parallel to the y-axis.

[0036] As illustrated in Fig. 3, an intake and exhaust passage (550) surrounding a hollow space (S50) is formed in the lower mold (503). As indicated by the arrow, gas flows into the hollow space (S50) while rotating around the hollow space (S50) to pressurize the hollow space (S50). In this case, the hollow space (S50) is pressurized to 5 to 60 bar. The pressure in the hollow space (S50) is maintained within the aforementioned range so that the mixture can be properly foamed.

[0037] An external outlet (5505) is formed in the lower mold (503) to introduce gas into the intake / exhaust passage (550) or exhaust gas from the intake / exhaust passage (550). The two ends of the intake / exhaust passage (550) along the vertical direction of the hollow space (S50), i.e., the y-axis direction, include an upper end (5501) and a lower end (5503), respectively. Intake / exhaust holes (5501a) are formed in the upper end (5501) and communicate with the hollow space (S50). In addition, intake / exhaust holes (5503a) are formed in the lower end (5503) and communicate with the hollow space (S50). The upper part of the midsole, which is foamed in the hollow space (S50), is formed thinner than the lower part. Since foaming of the mixture injected into the hollow space (S50) is induced by the exhaust of the gas, the intake pressure is increased to form the lower part thicker. Accordingly, the number of intake and exhaust holes (5503a) at the bottom (5503) is set to 5, and the number of intake and exhaust holes (5501a) at the top (5501) is set to 4, so that the number of intake and exhaust holes (5503a) is greater than the number of intake and exhaust holes (5501a). As a result, the exhaust pressure through the intake and exhaust holes (5503a) is greater than the exhaust pressure through the intake and exhaust holes (5501a), so that a midsole having a shape in which the lower part is thicker than the upper part can be manufactured.

[0038] Intake and exhaust are performed through valves (VL1, VL2, VR1, VR2). The valves (VL1, VL2, VR1, VR2) are connected to an intake and exhaust path (5503) corresponding to the vertical length of the hollow space (S50). Therefore, intake and exhaust of the hollow space (S50) are possible while maintaining a uniform pressure distribution in the hollow space (S50).

[0039] As illustrated in Fig. 3, two valves on the left and right are connected to an external outlet (5505). When exhausting, the valves (VL1, VR1) are opened first, and then the valves (VL2, VR2) are opened to control the pressure in the hollow space (S50). That is, the valves (VL1, VR1) are opened first, and then the valves (VL2, VR2) are opened 0.5 to 1 second later. Therefore, a midsole with uniform foaming can be manufactured through a stable injection process.

[0040] The opening degrees of the valves (VL1, VR1) may be smaller than the opening degrees of the valves (VL2, VR2). That is, if the hollow space (S50) is suddenly depressurized, the injection quality may become uneven. Therefore, the opening degrees of the valves (VL1, VR1) are made relatively small, and the opening degrees of the valves (VL2, VR2) are adjusted to be relatively large. The opening degree here means the ratio of the partially opened area to the 100% open area of ​​the valves. The opening degrees of the valves (VL1, VR1) may be 20% to 40%. In addition, the opening degrees of the valves (VL2, VR2) may be 50% to 70%. In this way, by adjusting the opening degrees of the valves (VL1, VR1, VL2, VR2), a low-density member in which foaming is uniformly performed can be manufactured.

[0041] Fig. 4 schematically illustrates a state in which a mixture is foamed while being injected into a hollow mold. The mixture (M) (illustrated in Fig. 2, hereinafter the same) begins to be injected through the injection gate (505) (illustrated in Fig. 2). The mixture (M) is injected at three locations arranged along the longitudinal direction of each hollow space (S50). The mixture (M) can be injected into the hollow space (S50) at a pressure of 3 MPa to 300 MPa. If the injection pressure is too low, the mixture (M) may not flow in properly. In addition, the injection pressure cannot be too high in terms of process design.

[0042] Meanwhile, the depressurization in the hollow space (S50) and the injection of the mixture (M) may be performed simultaneously. The injection of the mixture (M) may be performed first, and then the depressurization of the hollow space (S50) may be performed. For example, the hollow space (S50) may be pressurized to 10 to 50 bar and then depressurized. More preferably, the hollow space (S50) may be pressurized to 10 to 20 bar. If the pressurization force is too high or too low, it may be difficult to obtain an appropriate counterpressure optimized for foaming of the mixture (M). Therefore, the pressurization force of the hollow space (S50) is maintained within the aforementioned range. The decrease in the injection pressure of the mixture (M) over time during the injection of the mixture (M) and the exhaust amount of gas over time during the gas exhaust step may be substantially the same. As a result, a midsole of uniform quality can be manufactured.

[0043] Returning to Figure 1, in step (S20), the midsole (101) is inserted into another mold (52) in which an opening is formed, and the lower surface (1011) of the midsole (101) is exposed upward through the opening. This is described in detail with reference to Figure 5.

[0044] Figure 5 schematically illustrates a state in which a midsole (101) is joined to a mold (52). Figure 5 is merely illustrative of the present invention, and the present invention is not limited thereto. Accordingly, it can be modified in various ways.

[0045] As illustrated in Fig. 5, the mold (52) includes a left mold portion (521) and a right mold portion (523). The right mold portion (523) is separable from the left mold portion (521) in the x-axis direction, i.e., in the lateral direction. The left mold portion (521) and the right mold portion (523) are positioned on the side of the midsole (101) and are coupled to each other in the width direction to form an opening (S52). The left mold portion (521) and the right mold portion (523) can be reused. The left mold portion (521) and the right mold portion (523) are interlocked to form an opening (S52), and the midsole (101) is positioned in the opening (S52). The left mold portion (521) and the right mold portion (523) are positioned to completely surround the midsole (101).

[0046] The depth (d) of the opening (S52) is greater than the average thickness (t) of the midsole (101). Therefore, a space is formed under the back surface (1011) of the midsole (101). The outsole is injection-molded in this space. Although not illustrated in Fig. 5, the left mold portion (521) and the right mold portion (523) are located on the side surfaces of the combined sole, so that the internal shapes thereof can be processed to easily form an undercut shape or a perforated shape in the outsole.

[0047] Fig. 6 schematically illustrates a partial back structure of the mold (52) of Fig. 5. That is, Fig. 6 illustrates a state in which the left mold portion (521) and the right mold portion (523) are combined on both sides of the midsole (101) of Fig. 5 and flipped 180°. The enlarged circle of Fig. 6 schematically illustrates an enlarged view of the back surface (1011) of the midsole (101). The partial back structure of the mold (52) of Fig. 6 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the partial back structure of the mold (52) can be modified differently.

[0048] As illustrated in Fig. 6, the area of ​​the opening (S521) in contact with the lower surface (520) of the mold (52) is larger than the planar area of ​​the midsole (101). The opening (S521) refers to a planar space located on the same plane as the lower surface (520) of the mold (52). The extended portion (525) is formed by extending along the edge from the space where the midsole (101) is located. When the outsole is injection-molded on the midsole (101), the extended portion (525) causes the outsole to gather on the midsole (101), thereby further increasing the adhesive strength between the midsole (101) and the outsole. The extended portion (525) surrounds the planar area of ​​the midsole (101), thereby forming an area of ​​the opening (S521) that is not shared with the planar area of ​​the midsole (101). These non-shared areas are located surrounding the planar area of ​​the midsole (101).

[0049] In one embodiment of the present invention, a solid injection-molded outsole is bonded to a foam-molded midsole (101). This contrasts with the conventional method of inserting a pre-fabricated outsole or support into a mold and then foam-molding the midsole to surround it. Because the outsole has a high density and continuous molecular structure, remelting the solidified outsole requires a lot of energy. Therefore, when a solid outsole is inserted into a hollow space of a mold and then injection-molded, the mixture must melt and fuse the surface of the outsole to improve the bonding strength between the midsole and the outsole. However, due to these characteristics of the outsole, the bonding strength between the midsole and the outsole is low. In particular, the midsole has many pores due to the injection molding, which reduces the contact area with the outsole and also results in poor heat transfer performance due to the injection molding, making it difficult to properly melt the contact surface with the outsole. In contrast, in one embodiment of the present invention, the outsole is injection-molded into the midsole, thereby solving the aforementioned problems.

[0050] Meanwhile, as illustrated in the enlarged circle of FIG. 6, protrusions (1011a) may be formed as an auxiliary means to further enhance the adhesive strength between the midsole (101) and the outsole. The protrusions (1011a) are formed on the back surface (1011) of the midsole (101). These protrusions (1011a) are formed before the midsole (101) is joined to the mold (52). For example, only the portion of the back surface (1011) of the midsole (101) where the protrusions (1011a) are located may be masked, and then the back surface (1011) may be etched with a resin etchant to form the protrusions (1011a). The protrusions (1011a) anchor the outsole, which is injection-molded on the midsole (101), to further enhance the adhesive strength between the midsole (101) and the outsole. The etching process for forming the protrusions (1011a) can be easily invented by a person having ordinary skill in the art to which the present invention pertains, and therefore, a detailed description thereof is omitted.

[0051] Meanwhile, instead of forming protrusions (1011a), the back surface (1011) of the midsole (101) may be surface-treated to increase its surface roughness. In this case, the surface roughness may be 10 μm to 1000 μm. More preferably, the surface roughness may be 10 μm to 500 μm. If the surface roughness is too high, the surface adhesion strength between the midsole (101) and the outsole may be too low. Furthermore, if the surface roughness is too low, the surface treatment process may be unnecessary. Therefore, it is preferable to maintain the surface roughness of the back surface (1011) within the aforementioned range.

[0052] Returning to Figure 1, step (S30) provides a composite sole in which an outsole is injected through an opening and attached to the back surface of the midsole. This will be described in more detail with reference to Figures 7 and 8.

[0053] Fig. 7 schematically illustrates a state in which an outsole (103) is injection-molded into the mold (52) of Fig. 6. The enlarged circle in Fig. 7 schematically illustrates the cross-sectional structure of a combined sole (10) in which an outsole (103) is attached to a midsole (101). The injection-molded state of the outsole (103) in Fig. 7 is merely for illustrative purposes, and the present invention is not limited thereto. Accordingly, it can be modified in other ways.

[0054] As illustrated in Fig. 7, an outsole (103) is injected into an opening surrounded by a left mold portion (521) and a right mold portion (523). The outsole (103) is attached to the midsole (101) to form a combined sole (10). That is, a shoe component in which the midsole (101) and the outsole (103) are combined can be manufactured without using an adhesive.

[0055] As shown in the enlarged image of Fig. 7, the outsole (103) is formed on the midsole (101). The outsole (103) is firmly bonded to the midsole (101) and thus has high bonding strength.

[0056] The outsole (103) may be made of a thermoplastic resin. For example, the outsole (103) may be made of a material having wear resistance, such as TPEE (Thermoplastic Polyester Elastomer), TPE (Thermoplastic Elastomer), PEBA (Polyether Block Amide), TPU (Thermoplastic Polyurethane), TPV (Thermoplastic Vulcanizates), or EVA (Ethylene-Vinyl Acetate).

[0057] Figure 8 schematically illustrates a state in which the outsole raw material (103a) in section VIII of Figure 7 is melted and bonded to the midsole (101). The melted and bonded state of the outsole raw material (103a) in Figure 8 is merely illustrative of the present invention, and the present invention is not limited thereto. Accordingly, it can be modified in other ways.

[0058] As illustrated in Fig. 8, the midsole (101) is formed by physical foaming injection in a mold at room temperature. Therefore, a closed skin (1017) is formed on the outer surface of the midsole (101) by rapid cooling due to mold contact. A plurality of pores (1019) are formed on the inner surface of the midsole (101) by foaming. That is, the plurality of pores (1019) are surrounded by the closed skin (1017). The outsole raw material liquid (103a) is injected onto the midsole (101). Since the outsole raw material liquid (103a) is pressurized, injected at a high speed, and is hot, the outsole raw material liquid (103a) partially forms perforations (1017a) in the closed skin (1017) and penetrates into the interior of the midsole (101). As a result, the outsole raw material (103a) penetrates the pores (1019) and melts the surrounding area, solidifying as the temperature decreases. The width of the solidified outsole raw material (103a) through the pores (1017a) is larger than the width of the pores (1017a). Therefore, a structure is formed in which the outsole (103) (as shown in FIG. 7) is anchored to the midsole (101). In this way, since the outsole (103) is melted and merged with the midsole (101), the bonding strength between the outsole (103) and the midsole (101) is very excellent.

[0059] The injection speed of the outsole raw material for this purpose can range from 30 mm / sec to 200 mm / sec. If the injection speed is too low, the outsole may not be formed properly. Furthermore, if the injection speed is too high, the outsole solution, which generates high heat in a short period of time, may partially deform the midsole. Therefore, the injection speed of the outsole raw material is adjusted within the aforementioned range.

[0060] Additionally, the injection temperature of the outsole raw material may be between 100°C and 250°C. More preferably, the injection temperature of the outsole raw material may be between 150°C and 250°C. If the injection temperature of the outsole raw material is too low, it may not adhere well to the midsole. Furthermore, if the injection temperature of the outsole raw material is too high, the midsole may deteriorate. Therefore, the injection temperature of the outsole raw material is maintained within the aforementioned range.

[0061] The injection pressure of the outsole raw material may be 30 MPa to 300 MPa. More preferably, the injection pressure of the outsole raw material may be 50 MPa to 200 MPa. If the injection pressure of the outsole raw material is too low, the molding of the outsole may be incomplete. Furthermore, if the injection pressure of the outsole raw material is too high, the midsole may be deformed. Therefore, the injection pressure of the outsole raw material is adjusted within the aforementioned range.

[0062] Returning to Figure 1, in the final step (40), the composite sole is separated from the second mold. As a result, a composite sole formed integrally with the midsole and outsole can be obtained.

[0063] Fig. 9 schematically illustrates a flowchart of a method for manufacturing composite injection-molded shoes according to a second embodiment of the present invention. The method for manufacturing composite injection-molded shoes of Fig. 9 is merely illustrative of the present invention and is not intended to limit the present invention. Accordingly, the method for manufacturing composite injection-molded shoes may be modified in other forms. Since the method for manufacturing composite injection-molded shoes of Fig. 9 is similar to the method for manufacturing composite injection-molded shoes of Fig. 1, the same reference numerals are used for identical parts, and a detailed description thereof is omitted.

[0064] As illustrated in Fig. 9, the method for manufacturing a composite injection-molded shoe includes a step (S12) of providing an upper including a sole, a step (S22) of fixing the upper to the mold while covering an opening formed in the mold with the sole, a step (S32) of physically foam-molding a midsole into the mold to provide a composite sole in which the sole is attached to the midsole, and a step (S42) of removing the composite sole from the mold. In addition, the method for manufacturing a composite injection-molded shoe may further include other steps.

[0065] First, in step (S12), an upper including a sole is provided. The upper is attached to a midsole and manufactured as an integrated composite sole in a subsequent process.

[0066] Next, in step (S22), the upper is secured to the mold while covering the opening formed in the mold with the floor. This method completes the process of physically foaming the midsole. This process is described in more detail in Figure 10.

[0067] Fig. 10 schematically illustrates a state in which an upper (105) is attached to a mold (54). Fig. 10 is merely illustrative of the present invention, and the present invention is not limited thereto. Accordingly, it can be modified in various ways.

[0068] As illustrated in Fig. 10, the mold (54) includes a left mold portion (541) and a right mold portion (543). The right mold portion (543) is separable from the left mold portion (521) in the x-axis direction, i.e., the lateral direction. The left mold portion (521) and the right mold portion (523) are positioned on the side of the upper (105) and are coupled to each other in the width direction to form an opening (54S). The left mold portion (541) and the right mold portion (543) can be reused. The left mold portion (541) and the right mold portion (543) are interlocked to form an opening (S54), and the upper (105) is positioned in the opening (S54). Therefore, the left mold portion (541) and the right mold portion (543) are positioned to completely surround the bottom (1051) of the upper (105). The bottom (1051) of the upper (105) faces the lower side where the midsole is physically foam-molded in a subsequent process. The mold (54) of Fig. 10 can be rotated 180° about the x-axis and flipped over to physically foam-mold the midsole onto the bottom (1051) of the upper (105) to manufacture a composite sole. Meanwhile, the material of the bottom (1051) of the upper (105) is modified so that the upper (105) is well attached to the midsole that is physically foam-molded in a subsequent process. This will be described in more detail with reference to Figs. 11 to 13.

[0069] Figures 11 to 13 schematically illustrate various examples of the bottom (1051) structure of the upper (105) of Figure 10 in an enlarged manner. Figures 11 to 13 are merely illustrative of the present invention, and the present invention is not limited thereto. Accordingly, the bottom (1051) structure of the upper (105) may be modified differently.

[0070] Figure 11 illustrates a woven fabric in which yarn bundles (1051a) and polymer strings (1051b) are interwoven. The left-hand image of Figure 11 shows this fabric at a 60-fold magnification, and the right-hand image of Figure 11 shows this fabric at a 205-fold magnification.

[0071] As illustrated in Fig. 11, yarn bundles (1051a) are arranged in parallel and spaced apart from each other. Since each yarn is very thin, bundling them together increases the surface area and enhances the penetration of the midsole foam in contact with it. Since the yarn is elastic, it is suitable for use as a material for the upper (105). Fusible yarn can be used as the yarn.

[0072] Meanwhile, the polymer string (1051b) is manufactured by stretching and drawing a polymer material. The manufacturing process of this polymer string (1051b) is readily understandable to those skilled in the art to which the present invention pertains, and thus a detailed description thereof will be omitted.

[0073] Thermoplastic polyester elastomer (TPE), thermoplastic polyurethane (TPU), thermoplastic copolyester elastomer (TPC-ET), or polyether block amide (PEBA) can be used as the material for the polymer strings (1051b). These polymer materials are also used as raw materials for the midsole. Therefore, by using a material that is compatible with and highly compatible with the midsole raw material, the bonding strength can be further increased.

[0074] As illustrated in Fig. 11, the polymer strings (1051b) are positioned to intersect with the yarn bundles (1051a). Since the upper (105) is formed in the form of a woven material, the yarn bundles (1051a) and the polymer strings (1051b) are formed to be spaced apart from each other and intertwined. More specifically, the polymer strings (1051b) are provided by intertwining with the yarn bundles (1051a) while alternately passing through the upper and lower portions of the yarn bundles (1051a). If the structure of the woven pattern is too solid or densely woven, the mixture for manufacturing the midsole may only contact the floor, but in the aforementioned pattern, foaming is also formed in the space existing between the polymer strings (1051b) and the yarn bundles (1051a), thereby improving the bonding strength.

[0075] Meanwhile, the average width (w1051a) of the yarn bundles is larger than the average width (w1051b) of the polymer strings (1051b). That is, by forming the yarn bundles (1051a) thick, the elasticity of the upper (105) can be increased. That is, the polymer strings (1051b) having relatively lower elasticity than the yarn bundles (1051a) can secure the elasticity of the upper (105) by making their average width (w1051b) smaller. The polymer strings (1051b) facilitate attachment to the midsole. Furthermore, since the foam-molded midsole penetrates between the yarn bundles (1051a) and the polymer strings (1051b), the attachment strength between the upper (105) and the midsole can be further enhanced.

[0076] Fig. 12 illustrates another state in which yarn bundles (1051a) and polymer strings (1051b) are interwoven. The left-hand photograph of Fig. 12 shows this woven fabric at a 60x magnification, and the right-hand photograph of Fig. 12 shows this woven fabric at a 200x magnification. Since Fig. 12 is similar to Fig. 11, the same reference numerals are used for the same parts, and a detailed description thereof is omitted.

[0077] As illustrated in FIG. 12, a pair of polymer strings (1051b) are formed by being twisted together. Two or more yarn bundles (1051a) are positioned between a pair of polymer strings (1051b) that are alternately positioned vertically. As a result, the yarn bundles (1051a) can be stably fixed between the pair of polymer strings (1051b), thereby further enhancing the durability of the upper (105) (illustrated in FIG. 10).

[0078] Figure 13 illustrates another state in which yarn and polymer are intermixed by electrospinning. The left image of Figure 13 shows this fabric at a 55x magnification, and the right image of Figure 13 shows this fabric at a 205x magnification. The material of the upper of Figure 13 is the same as that of the upper of Figures 11 and 12, and therefore a detailed description thereof is omitted.

[0079] As illustrated in Fig. 13, a nonwoven fabric randomly formed by electrospinning yarn and polymer can be used as a material for the upper (105) (illustrated in Fig. 10). Since the electrospinning method can be easily understood by those of ordinary skill in the art to which the present invention pertains, a detailed description thereof will be omitted.

[0080] Returning to Figure 9, step (S32) provides a composite sole in which the midsole is physically foam-injected into a mold to attach the bottom to the midsole. This is described in detail with reference to Figure 14.

[0081] Fig. 14 schematically illustrates a partial rear surface structure of the mold (54) of Fig. 10. That is, Fig. 14 illustrates a state in which the left mold portion (541) and the right mold portion (543) are joined on both sides of the upper skin (105) of Fig. 10 and turned over. The partial rear surface structure of the mold (54) of Fig. 14 is merely for illustrative purposes, and the present invention is not limited thereto. Accordingly, the partial rear surface structure of the mold (54) may be modified differently.

[0082] As illustrated in Fig. 14, a mixture for manufacturing a midsole is physically foam-injected from three injection gates (505) onto the bottom (1051) of the upper (105). Three injection gates (505) arranged in parallel in the longitudinal direction of the shoe are used to provide uniform adhesive strength to the entire bonding area between the upper (105) and the midsole.

[0083] The physical foam injection molding process can be performed by inserting the mold (54) as a core into the mold (50) of FIG. 2. That is, the upper (105) is fixed to the mold (54), so that the upper (105) is placed downwards and its bottom (1051) is exposed upwards. The midsole is physically foam injected onto the bottom (1051). The physical foam injection molding process including this is similar to the physical foam injection molding process in step (S10) of FIG. 1, and thus a detailed description thereof will be omitted. The remaining detailed processes can be easily understood by those skilled in the art to which the present invention pertains, and thus a detailed description thereof will be omitted.

[0084] In the past, a rim was formed to secure the injection-molded product to the mold, or a film larger than the hollow space was used. Therefore, a process for trimming the edges of the combined sole after molding was essential. Furthermore, since a large amount of raw material was used compared to the hollow space to maintain pressure during molding of the midsole, flash occurred due to overflow. Furthermore, since the upper and midsole had to be bonded using an adhesive, there were limitations in designs that allowed for simultaneous molding of the upper and midsole. In contrast, the second embodiment of the present invention can overcome the aforementioned problems through the aforementioned process.

[0085] The present invention is described in detail below through experimental examples. These experimental examples are intended solely to illustrate the present invention and are not intended to limit the present invention.

[0086] Experimental manufacturing of a combined midsole and outsole

[0087] Experimental Example 1

[0088] The midsole and outsole were molded simultaneously according to the manufacturing method of Fig. 1. TPU was used as the material for both the midsole and outsole.

[0089] Fig. 15 shows a photograph of a mold for manufacturing a midsole according to an experimental example of the present invention. Fig. 15 has the same structure as the mold of Fig. 6.

[0090] Figure 16 illustrates a photograph of one of the midsoles produced by physical foam injection molding according to an experimental example of the present invention. As illustrated in Figure 16, the midsole was physically foam injected into a hollow space of a mold. Above the midsole, a space exists for injection molding an outsole through an expanded portion of the mold.

[0091] Figure 17 shows a photograph of a composite sole in which an outsole is injection-molded over the midsole of Figure 16. As shown in Figure 17, the midsole and outsole can be manufactured by combining them.

[0092] Experimental Example 2

[0093] Another fusion brush was manufactured using the same method as Experimental Example 1. In Experimental Example 2, the fusion brush was manufactured using the same method as Experimental Example 1, so the detailed experimental process is omitted.

[0094] Comparative Example 1

[0095] In contrast to Experimental Examples 1 and 2 described above, a TPU outsole was manufactured by injection molding. The manufactured outsole was inserted into the hollow space of a mold. A midsole was formed on the outsole using a physical foaming injection process using a mixture of TPU and nitrogen, a supercritical fluid, as raw materials, to manufacture a composite sole. The remaining experimental procedures are readily apparent to those skilled in the art, and therefore, a detailed description thereof will be omitted.

[0096] Experimental results

[0097] The adhesive strength of the midsole and the outsole was measured by setting 13 points in Comparative Example 1, 16 points in Experimental Example 1, and 12 points in Experimental Example 2 on the composite soles manufactured according to the aforementioned Experimental Example 1, Experimental Example 2, and Comparative Example 1. In the composite soles of Experimental Example 1, Experimental Example 2, and Comparative Example 1, each point was located at the same location. The results of the adhesive strength measurement are shown in Table 1 below.

[0098] Unit (kgf / cm) Comparative Example 1 Experimental Example 1 Experimental Example 2 Points 10.70 2.90 2.90 points 21.00 3.10 3.00 points 30.80 3.70 2.70 points 41.20 2.80 2.90 points 50.50 3.60 2.80 points 60.00 2.60 2.50 points 71.50 3.70 2.70 points 81.70 3.00 3.20 points 91.00 2.70 2.80 points 101.20 3.00 3.50 points 110.90 3.30 3.30 points 120.80 3.00 3.10 points 131.00 3.70-points 14-3.50-points 15-3.40-points 16-3.00-average 0.943.192.95

[0099] As described in Table 1, the average adhesive strength of the composite sole of Comparative Example 1 was 0.94 kgf / cm, while the average adhesive strengths of the composite soles of Experimental Examples 1 and 2 were measured as 3.19 kgf / cm and 2.95 kgf / cm, respectively. Therefore, it was found that the composite soles manufactured according to Experimental Examples 1 and 2 of the present invention had higher adhesive strengths than the composite sole manufactured according to Comparative Example 1.

[0100] Experimental manufacturing of a combined upper and midsole

[0101] Experimental Example 3

[0102] The upper and midsole were molded simultaneously according to the manufacturing method of Fig. 9. The upper was manufactured by weaving yarn and TPU, and PEBAX was used as the material for the midsole.

[0103] Fig. 18 shows a photograph of the upper part joined to the mold according to Experimental Example 3 of the present invention. The mold of Fig. 18 has the same structure as the mold of Fig. 14.

[0104] Figure 19 shows a photograph of a composite sole attached to an upper by physical foam injection molding of a midsole according to Experimental Example 3 of the present invention. That is, the midsole was physically foam injection molded beneath the upper fixed to the mold of Figure 18. As illustrated in Figure 19, the physical foam injection molded midsole was confirmed beneath the upper.

[0105] Experimental Example 4

[0106] TPEE was used as the midsole material. The remaining experimental procedures were identical to Experimental Example 3 described above.

[0107] Experimental Example 5

[0108] TPU was used as the midsole material. The remaining experimental procedures were identical to Experimental Example 3 described above.

[0109] Comparative Example 2

[0110] A film was inserted between the upper sole and the physico-foam-molded midsole to bond the upper and midsole. TPU was used as the midsole material. TPU was also used as the film material.

[0111] Experimental results

[0112] In the composite soles manufactured according to Experimental Examples 3 to 5 and Comparative Example 2 described above, 15 points were set for Comparative Example 2, 17 points for Experimental Example 3, 20 points for Experimental Example 4, and 19 points for Experimental Example 5, and the adhesive strength between the upper and the midsole was measured. In the composite soles of Experimental Examples 3 to 5 and Comparative Example 2, each point was located at the same position. The results of the adhesive strength measurement are shown in Table 2 below.

[0113] Unit (kgf / cm) Comparative Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Points 11.40 4.50 3.50 2.60 Points 21.20 3.70 4.30 2.20 Points 32.00 3.90 3.90 3.00 Points 41.50 3.00 4.30 2.70 Points 50.80 3.10 5.20 3.10 Points 60.90 3.60 4.60 2.20 Points 70.80 3.70 3.50 2.70 Points 81.00 2.10 4.30 1.40 Points 91.70 3.00 3.90 1.50 Points 102.30 3.30 4.102.60 Points 111.80 3.10 3.90 2.50 Points 121.50 3.20 4.10 2.60 points 131.00 3.00 3.40 2.30 points 141.70 3.10 4.60 2.40 points 151.60 2.80 5.10 2.20 points 163.00 2.70 1.80 points 17-2.20 1.70 points 18-3.10 2.20 points 19-3.00 2.10 points 20-2.00 - average 1.41 3.26 3.79 2.31 points

[0114] As described in Table 2, the average adhesive strength of the composite sole of Comparative Example 2 was 1.41 kgf / cm, while the average adhesive strengths of the composite soles of Experimental Examples 3 to 5 were measured as 3.26 kgf / cm, 3.79 kgf / cm, and 2.31 kgf / cm, respectively. Therefore, it was found that the composite soles manufactured according to Experimental Examples 3 to 5 of the present invention had higher adhesive strengths than the composite sole manufactured according to Comparative Example 2. In addition, in Experimental Examples 3 and 4, adhesive strengths higher than the general adhesive strength standard of 2.7 kgf / cm were obtained.

[0115] Although the present invention has been described in the foregoing manner, those skilled in the art will readily understand that various modifications and variations are possible without departing from the concept and scope of the patent claims set forth below.

Claims

1. A step for providing a midsole that has been physically foam-molded in a mold. A step of inserting the midsole into another mold having an opening formed therein and exposing the back surface of the midsole to the upper side through the opening; A step for providing a composite sole by injecting an outsole through the above opening and attaching it to the back surface of the midsole, and A step of separating the above-mentioned composite sole from the above-mentioned another mold. Including, A method for manufacturing a composite injection-molded shoe, wherein, in the step of providing the composite sole, the raw material liquid of the outsole is pressurized to form a perforation in the closed skin of the midsole formed in the step of providing the midsole, penetrate into the interior of the midsole, and penetrate into a plurality of pores surrounded by the closed skin, melting the surrounding area and solidifying.

2. In paragraph 1, In the step of exposing the back surface of the midsole to the upper side, Another mold mentioned above is, Left mold part, and The left mold part above and the right mold part that can be separated in the lateral direction Including, The above left mold portion and the above right mold portion are joined to each other in the width direction to form the above opening, A method for manufacturing a composite injection-molded shoe, wherein the depth of the opening is greater than the average thickness of the midsole.

3. In paragraph 1, A method for manufacturing a composite injection-molded shoe, wherein, in the step of providing the midsole, the midsole is manufactured from at least one resin selected from the group consisting of a thermoplastic elastomer (TPE), a thermoplastic polyurethane (TPU), a thermoplastic copolyester elastomer (TPC-ET), a polyether block amide (PEBA), a polycarbonate (PC), and a styrene-ethylene-butylene-styrene (SEBS).

4. In paragraph 3, A method for manufacturing a composite injection-molded shoe, wherein, in the step of providing the composite sole, the outsole is manufactured from at least one resin selected from the group consisting of TPEE (Thermoplastic Polyester Elastomer), Thermoplastic Elastomer (TPE), PEBA (Polyether Block Amide), TPU (Thermoplastic Polyurethane), TPV (Thermoplastic Vulcanizates), and EVA (Ethylene-Vinyl Acetate).

5. In paragraph 1, A method for manufacturing a composite injection-molded shoe, wherein in the step of exposing the back surface of the midsole, the back surface is surface-treated to increase its surface roughness.

6. In paragraph 5, A method for manufacturing a composite injection-molded shoe having a surface roughness of 10 ㎛ to 1000 ㎛.

7. In paragraph 1, A method for manufacturing a composite injection-molded shoe, wherein, in the step of exposing the back surface of the midsole, the back surface is etched to form a plurality of protrusions on the back surface.

8. In paragraph 1, In the step of providing the above midsole, the mold includes an upper mold part and a lower mold part, and the upper mold part and the lower mold part are combined to form a hollow space. The step of providing the above midsole is: A step of providing a mixture in which a supercritical fluid is mixed into a melt; A step of pressurizing the hollow space by sucking gas into the hollow space; A step of injecting the mixture into the hollow space and foaming the mixture in the hollow space; A step of multi-stage depressurizing the hollow space after injection of the mixture, and A step of separating the upper mold part and the lower mold part from each other and taking out the foamed midsole. Including, In the step of foaming the mixture, an intake and exhaust passage surrounding the hollow space is formed in the lower mold portion, A method for manufacturing a composite injection-molded shoe, wherein the vertical length of the hollow space is greater than the horizontal length of the hollow space intersecting the vertical direction at a right angle, a plurality of intake and exhaust holes are formed in each of the intake and exhaust passages located at both ends in the vertical direction, and the plurality of intake and exhaust holes are connected to the hollow space.

9. In paragraph 8, A method for manufacturing a composite injection-molded shoe, wherein the injection speed of the mixture in the step of foaming the mixture and the decompression speed of the hollow space in the step of multi-stage decompression of the hollow space are substantially the same.

10. In paragraph 1, In the step of exposing the back surface of the midsole upward through the opening, the area of ​​the opening in contact with the lower surface of the other mold is larger than the flat surface area of ​​the midsole, A method for manufacturing a composite injection-molded shoe, wherein an area of ​​the opening that is not shared with the planar area of ​​the midsole surrounds the planar area of ​​the midsole.

11. A step of providing an upper including a floor, A step of fixing the upper to the mold while covering the opening formed in the mold with the bottom; A step of providing a composite sole by physically foaming-molding a midsole into the mold and attaching the bottom to the midsole, and A step of taking the above-mentioned composite sole out of the above-mentioned mold Including, In the step of providing the upper, the upper, a plurality of bundles of yarns, and A plurality of polymer strings intertwined with the above plurality of yarn bundles A method for manufacturing a composite injection-molded shoe comprising:

12. In Article 11, The above multiple bundles of yarns are arranged side by side and spaced apart from each other, A plurality of polymer strings intersect with the plurality of yarn bundles and alternately pass through the upper and lower portions of the plurality of yarn bundles, A method for manufacturing a composite injection-molded shoe, wherein the average width of the plurality of yarn bundles is larger than the average width of the plurality of polymer strings.

13. In Article 12, A method for manufacturing a composite injection-molded shoe, wherein the plurality of polymer strings include a pair of polymer strings that are mutually twisted, and the pair of polymer strings are respectively positioned above and below each other, and two or more yarn bundles among the plurality of yarn bundles are positioned between them.

14. In Article 11, In the step of providing the above upper skin, The above upper is a method for manufacturing a composite injection-molded shoe formed by mixing yarn and polymer through electrospinning.

15. In paragraph 11, In the step of providing the above-mentioned composite sole, the mold includes an upper mold part and a lower mold part, and the upper mold part and the lower mold part are combined to form a hollow space. Physical foam injection of the midsole into the above mold, A step of providing a mixture in which a supercritical fluid is mixed into a melt; A step of pressurizing the hollow space by sucking gas into the hollow space; A step of injecting the mixture into the hollow space and foaming the mixture in the hollow space; A step of multi-stage depressurizing the hollow space after injection of the mixture, and A step of separating the upper mold part and the lower mold part from each other and taking out the foamed midsole. Including, In the step of foaming the mixture, an intake and exhaust passage surrounding the hollow space is formed in the lower mold portion, A method for manufacturing a composite injection-molded shoe, wherein the vertical length of the hollow space is greater than the horizontal length of the hollow space intersecting the vertical direction at a right angle, a plurality of intake and exhaust holes are formed in each of the intake and exhaust passages located at both ends in the vertical direction, and the plurality of intake and exhaust holes are connected to the hollow space.

16. In Article 15, A method for manufacturing a composite injection-molded shoe, wherein the injection speed of the mixture in the step of foaming the mixture and the decompression speed of the hollow space in the step of multi-stage decompression of the hollow space are substantially the same.

17. In either of paragraphs 1 and 11, A method for manufacturing a composite injection-molded shoe, wherein in the step of providing the above-mentioned composite sole, the injection speed of the raw material of the above-mentioned outsole is 30 mm / sec to 200 mm / sec.

18. In either of paragraphs 1 and 11, A method for manufacturing a composite injection-molded shoe, wherein in the step of providing the composite sole, the injection pressure of the raw material of the outsole is 30 MPa to 300 MPa.

19. In either of paragraphs 1 and 11, A method for manufacturing a composite injection-molded shoe, wherein in the step of providing the above-mentioned composite sole, the injection temperature of the raw material of the above-mentioned outsole is 100°C to 250°C.

20. The upper including the bottom, and Midsole attached to the floor above As a composite injection shoe including: The above upper part, A plurality of bundles of yarns arranged side by side and spaced apart from each other, and A plurality of polymer strings intersecting with the plurality of yarn bundles and alternately passing through the upper and lower portions of the plurality of yarn bundles, respectively, and intertwined with the plurality of yarn bundles Including, The average width of the plurality of yarn bundles is greater than the average width of the plurality of polymer strings, A composite injection-molded shoe in which the plurality of polymer strings include a pair of polymer strings that are mutually twisted, and the pair of polymer strings are respectively positioned above and below each other, and two or more yarn bundles among the plurality of yarn bundles are positioned between them.

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