Variable pressure control injection method, injection semi-finished product, and method for manufacturing co-injection part

Abstract

To provide a variable pressure control injection method and a method for manufacturing an injection semi-finished product and a co-injection member.SOLUTION: A variable pressure control injection method, comprising: providing an injection molding system comprising a first variable pressure mold and a second variable pressure mold; injecting a first foam material; and performing a foaming process, wherein the first variable pressure mold and the second variable pressure mold respectively apply a first pressure and a second pressure to the first foam material to heat and foam as an injection semi-finished product, and the first pressure is a variable pressure. The semi-finished injection product thus obtained has a microporous layer and a solidified layer, and can be further subjected to a molding process with a second foaming material and heated to complete foaming under a stable internal pressure to obtain a co-injection part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an injection method, an injection semi-finished product, and a method for manufacturing a coinjection member, and more particularly to a variable pressure control injection method, an injection semi-finished product, and a method for manufacturing a coinjection member. [Background technology]

[0002] Shoes are primarily intended to protect the feet and prevent them from being punctured by other sharp objects when the feet step on the ground. Shoes are known to include an upper structure and a sole structure, where the upper structure may be formed from any suitable material to cover, secure, and support the foot to the sole structure, and the sole structure typically includes an outsole, which is a layered arrangement extending between the ground and the upper structure and provides abrasion resistance and traction with the ground, and a midsole, which is disposed between the outsole and the upper structure.

[0003] Outsoles are typically made of materials such as rubber or leather because they must be non-slip, wear-resistant, and elastic to enhance traction with the ground. Meanwhile, midsoles are typically made at least in part of polymer foam materials to provide cushioning for the foot. The polymer foam material elastically compresses under load, attenuating the reaction force from the ground and thereby cushioning the force experienced by the foot. In a known process, the midsole and outsole of a sole structure are bonded together after undergoing steps such as roughening, washing with water, drying, applying a primer, drying, applying an adhesive, and re-drying. However, because the outsole and midsole are made of different materials and have different elastic moduli, hardness, or density, the sole structure suffers from well-known problems, such as a short service life, susceptibility to breakage, and the tendency for the outsole to separate from the midsole.

[0004] In addition, volatile organic compounds, which are often used in the adhesive application process in the sole construction process, are also likely to be harmful to humans and the environment. In light of this, developing a method that can tightly bond different materials in a sole construction without adding adhesives is a development goal with commercial value. Summary of the Invention [Problem to be solved by the invention]

[0005] The objective of the present invention is to provide a variable pressure control injection method, in which a first pressure and a second pressure are respectively applied to a first foam material during the foaming process, the first pressure and the second pressure are not equal, and the first pressure is a variable pressure, so as to obtain an injected semi-finished product having a microporous layer and a solidified layer.

[0006] Another object of the present invention is to provide a method for manufacturing a coinjection component, in which an injected semi-finished product having a microporous layer and a solidified layer and a second foam material are heated under a stable internal pressure until complete foaming occurs, thereby obtaining a coinjection component, in which different materials are tightly bonded without adding an adhesive. [Means for solving the problem]

[0007] One embodiment of the present invention provides a variable pressure control injection method, which includes the steps of: providing an injection molding system including a first variable pressure mold and a second variable pressure mold arranged opposite to each other in a foam molding space; injecting a first foam material into the foam molding space; and performing a foaming process in which the first variable pressure mold applies a first pressure to the first foam material and the second variable pressure mold applies a second pressure to the first foam material, heating the first foam material to foam it into an injected semi-finished product, where the first pressure and the second pressure are not the same and the first pressure is a variable pressure. The first variable pressure mold and the second variable pressure mold each include a mold body and a variable pressure porous layer arranged in the mold body, correspondingly exposed to the foam molding space, and having a plurality of variable pressure pores communicating with the foam molding space.

[0008] According to the above-mentioned variable pressure control injection method, the size of each variable pressure orifice of the first variable pressure mold may be 200 μm to 700 μm, and the size of each variable pressure orifice of the second variable pressure mold may be 200 μm to 700 μm.

[0009] According to the variable pressure control injection method described above, the third pressure may be applied as the first pressure for 1 to 5 seconds, and then increased to a fourth pressure that is greater than the third pressure.

[0010] According to the variable pressure control injection method described above, the fifth pressure may be applied as the first pressure for 1 to 5 seconds, and then the pressure may be reduced to a sixth pressure that is lower than the fifth pressure.

[0011] According to the variable pressure control injection method described above, the second pressure may be a fixed pressure.

[0012] According to the variable pressure control injection method described above, the first foam material may be a rubber foam material.

[0013] Another embodiment of the present invention provides an injected semi-finished product manufactured by the variable pressure controlled injection method described in the previous paragraph, wherein the end closer to the first variable pressure mold is a microporous layer and the end closer to the second variable pressure mold is a solidified layer.

[0014] According to the injection semi-finished product, the foaming degree of the microporous layer may be 30% to 80%, and the foaming degree of the solidified layer may be 50% to 100%.

[0015] Another embodiment of the present invention provides a method for manufacturing a coinjection component, comprising the steps of: providing the injected semi-finished product described in the previous paragraph; injecting a second foaming material into the microporous layer of the injected semi-finished product to obtain a coinjection component precursor; and heating the coinjection component precursor under a stable internal pressure until it is fully foamed to obtain the coinjection component.

[0016] According to the above-described method for manufacturing a coinjection member, the second foam material may be a thermoplastic material. [Effects of the Invention]

[0017] As a result, the variable pressure control injection method of the present invention can obtain an injected semi-finished product having a microporous layer and a solidified layer by controlling the pressure in the foaming process, and the co-injection component manufacturing method of the present invention can tightly bond a first material formed by completely foaming a first foam material and a second material formed by completely foaming a second foam material without adding an adhesive. [Brief explanation of the drawings]

[0018] To make the above and other objects, features, advantages and embodiments of the present invention more clearly and comprehensibly, the drawings are described as follows. [Figure 1] 1 is a process flow chart of a variable pressure control injection method according to one embodiment of the present invention. [Figure 2] FIG. 2 is a process diagram of the foaming step in the variable pressure control injection method of FIG. 1. [Figure 3] 2 is a schematic local view of the foaming process in the variable pressure control injection method of FIG. 1. FIG. [Figure 4] FIG. 10 is a schematic diagram of an injected blank according to another embodiment of the present invention. [Figure 5] 10 is a process flowchart of a method for manufacturing a coinjection member according to another embodiment of the present invention. [Figure 6] 10A and 10B are schematic diagrams of a coinjection member manufactured by a coinjection member manufacturing method according to another embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view of the coinjection member of FIG. 6 taken along line 7-7. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the present invention. That is, in some embodiments of the present invention, these practical details are not necessary. Furthermore, in order to simplify the drawings, some conventional structures and elements are simply illustrated in the drawings.

[0020] It should be clarified that in the specification and claims of the present invention patent, the terms prefixed with "first," "second," "third," "fourth," "fifth," or "sixth" are intended to distinguish the terms from one another, and unless a specific order is explained between the terms or the context does not indicate an order between the terms, the order between the terms is not limited to the prefixed "first," "second," "third," "fourth," "fifth," or "sixth."

[0021] Please refer to Figures 1, 2, 3 and 4. Figure 1 is a process flow chart of a variable pressure control injection method 100 according to one embodiment of the present invention, Figure 2 is a process schematic diagram of a foaming step in the variable pressure control injection method 100 of Figure 1, Figure 3 is a local schematic diagram of the foaming step in the variable pressure control injection method 100 of Figure 1, and Figure 4 is a schematic diagram of an injected semi-finished product 500 according to another embodiment of the present invention. In Figure 1, the variable pressure control injection method 100 includes steps 110, 120 and 130.

[0022] In step 110, an injection molding system 400 is provided. The injection molding system 400 includes a first variable pressure mold 200 and a second variable pressure mold 300, which are disposed opposite to each other and correspond to a foam molding space 401. The first variable pressure mold 200 includes a mold body 220 and a variable pressure porous layer 210, which is disposed in the mold body 220 and correspondingly exposed to the foam molding space 401, and which has a plurality of variable pressure pores 211 that communicate with the foam molding space 401. Cooling pipes 212 may be embedded in the variable pressure porous layer 210. The second variable pressure mold 300 includes a mold body 320 and a variable pressure porous layer 310. The variable pressure porous layer 310 is disposed in the mold body 320 and correspondingly exposed to the foam molding space 401. The variable pressure porous layer 310 is provided with a plurality of variable pressure pores 311 that communicate with the foam molding space 401. Cooling pipes 312 may be embedded in the variable pressure porous layer 310. The size of each variable pressure pore 211 in the first variable pressure mold 200 may be 200 μm to 700 μm. The variable pressure pores 211 may be distributed in a non-uniform network pattern or may be arranged in a uniformly spaced parallel array. The size of each variable pressure pore 311 in the second variable pressure mold 300 may be 200 μm to 700 μm. The variable pressure pores 311 may be distributed in a non-uniform network pattern or may be arranged in a uniformly spaced parallel array. The mold body 220 of the first variable pressure mold 200 includes a solid layer 221 and a base 222, the solid layer 221 is provided inside the base 222, and the variable pressure porous layer 210 is provided inside the solid layer 221. The mold body 320 of the second variable pressure mold 300 includes a solid layer 321 and a base 322, the solid layer 321 is provided inside the base 322, and the variable pressure porous layer 310 is provided inside the solid layer 321.

[0023] Step 120 is to inject a first foam material into the foam molding space 401. The first foam material may be a rubber foam material, such as thermoplastic polyurethane (TPU), ethylene vinyl acetate (EVA), synthetic rubber, thermoplastic elastomer (TPE), thermoplastic vulcanizate (TPV), polyether ester elastomer (TPEE), polyether block amide (PEBAX), TPU / TPV, TPV / TPU / rubber, or TPEE / TPV.

[0024] Step 130 is a foaming process, in which the first variable pressure mold 200 applies a first pressure P to the first foam material, and the second variable pressure mold 300 applies a second pressure P to the first foam material, heating the first foam material and foaming it into the injected semi-finished product 500. The first pressure P and the second pressure P are not the same; the first pressure P is a variable pressure. Furthermore, the first pressure P may be a third pressure applied for 1 to 5 seconds and then increased to a fourth pressure, or a fifth pressure applied for 1 to 5 seconds and then decreased to a sixth pressure, with the third pressure being smaller than the fourth pressure and the fifth pressure being larger than the sixth pressure. Preferably, the third pressure may be 5 to 30 bar, and the fourth pressure may be 10 to 90 bar. For example, the third pressure may be 5 bar and then increased to a fourth pressure of 60 bar. The fifth pressure may be 10 to 90 bar, and the sixth pressure may be 5 to 30 bar. For example, the fifth pressure of 30 bar may be applied for 1 to 5 seconds and then reduced to the sixth pressure of 5 bar. The first pressure P applied by the first variable pressure mold 200 is a variable pressure that affects the expansion degree of the first foam material and further forms a microporous layer 510 at the end of the injection semi-finished product 500 closest to the first variable pressure mold 200. The expansion degree of the microporous layer 510 may be 30% to 80%, and the first pressure P can be adjusted depending on the desired expansion degree. The second pressure may be a fixed pressure, preferably 5 to 80 bar. The second pressure applied by the second variable pressure mold 300 is a fixed pressure, which can stably foam the first foaming material, thereby forming a solidified layer 520 at the end of the injected semi-finished product 500 closest to the second variable pressure mold 300, and the foaming degree of the solidified layer 520 may be 50% to 100%.

[0025] Furthermore, the second pressure applied by the second variable pressure mold 300 may be a variable pressure, and the end of the injected semi-finished product 500 closer to the second variable pressure mold 300 may be in a state of low foaming. The second pressure can be adjusted according to the foaming degree to be achieved.

[0026] Please also refer to Figures 5, 6, and 7. Figure 5 is a process flowchart of a method 600 for manufacturing a coinjection member according to another embodiment of the present invention, Figure 6 is a schematic diagram of a coinjection member 700 manufactured by the method 600 for manufacturing a coinjection member according to another embodiment of the present invention, and Figure 7 is a schematic cross-sectional view of the coinjection member 700 taken along line 7-7 in Figure 6. In Figure 5, the method 600 for manufacturing a coinjection member includes steps 610, 620, and 630.

[0027] Step 610 is to provide an injection-molded blank 500 including a microporous layer 510 and a solidified layer 520, where the expansion degree of the microporous layer 510 may be 30%-80%, and the expansion degree of the solidified layer 520 may be 50%-100%.

[0028] Step 620 is to inject a second foaming material into the microporous layer 510 of the injected blank 500 to obtain a co-injected component precursor, and the second foaming material may be a thermoplastic material, such as thermoplastic polyurethane (TPU), polyether ester elastomer (TPEE), or polyether block amide (PEBAX).

[0029] Step 630 is a molding step in which the coinjected component precursor is heated under a stable internal pressure until it is fully foamed, thereby obtaining the coinjected component 700. Specifically, the coinjected component precursor is heated to 30°C to 100°C under a stable internal pressure ranging from 10 bar to 90 bar, until the coinjected component precursor is fully foamed. The microporous layer 510 of the injected semifinished product 500 contains incompletely foamed bubbles and micropores, which roughen the interface between the microporous layer 510 and the second foam material. The second foam material is then heated to dissolve in the microporous layer 510 of the injected semifinished product 500 and undergo secondary foaming. This allows the first material 710, which is fully foamed from the first foam material, and the second material 720, which is fully foamed from the second foam material, to be tightly bonded without adhesive, thereby obtaining the coinjected component 700.

[0030] As shown in Figures 6 and 7, the co-injection component 700 can be a shoe material, the first material 710 can be an outsole, and the second material 720 can be a midsole. The shoe material manufactured using the co-injection component manufacturing method 600 can tightly bond the outsole and midsole, further improving the problem of the outsole easily falling off the midsole and reducing the environmental pollution caused by the need for chemical solvent cleaning during the roughening and adhesive application processes in the sole construction process and the consumption of large amounts of water resources. However, depending on needs, the first material 710 can be a first midsole, and the second material 720 can be a second midsole. The co-injection component 700 may further include a third foam material, or may further include a carbon fiber plate or plastic plate between the second foam material and the injected semi-finished product 500. The co-injection component manufacturing method 600 of the present invention may coat the carbon fiber plate or plastic plate between the first material 710 and the second material 720, for example, as the intermediate layer of the midsole of a shoe material, and the first material 710 and the second material 720 may be the same or different. The present invention is not limited thereto.

[0031] <Test example>

[0032] To verify the bonding effect of the injection moldings produced by the variable pressure control injection method of the present invention with the first and second materials in the co-injection parts produced by the co-injection part manufacturing method of the present invention, a TPV / TPU / rubber foam with a Shore A hardness of 60±3 was used as the first foaming material in the test, and foaming processes were carried out at different first pressures to obtain the injection moldings of Comparative Example, Example 1, and Example 2. The first pressure applied to the injection moldings of Comparative Example 1 was 1 atm. The first pressure applied to the injection moldings of Example 1 was a third pressure of 30 bar applied for 1 to 5 seconds, which was then increased to a fourth pressure of 60 bar. The first pressure applied to the injection moldings of Example 2 was a fifth pressure of 60 bar applied for 1 to 5 seconds, which was then decreased to a sixth pressure of 30 bar. A thermoplastic material with a Shore C hardness of 25-65 was used as the second foam material. It was injected into the injection semifinished products of Comparative Example, Example 1, and Example 2, respectively, and a molding process was performed to obtain the coinjected components of Comparative Example, Example 1, and Example 2 (hereinafter abbreviated as Comparative Example, Example 1, and Example 2). The first and second materials of Comparative Example were bonded with an adhesive. The bond strength between the first and second materials of Comparative Example, Example 1, and Example 2 was evaluated according to ASTM D186. According to ASTM D186, 10 mm wide test specimens were tested. A measured tensile strength of 3.5 kg or greater was considered pass. The second material was then observed to see if it tore away from the first material. The bond strength was considered pass if only the second material tore. See Table 1 below for test results.

[0033] [Table 1]

[0034] As can be seen from the results in Table 1, the tensile strength values ​​for Examples 1 and 2 were all 3.5 to 4.5 kg or higher, significantly higher than the tensile strength values ​​for the Comparative Example, indicating that the first and second materials in Examples 1 and 2 were tightly bonded. Material fractures were observed in all Examples 1 and 2, while no material fractures were observed in the Comparative Example, indicating that the bond strength between the first and second materials in Examples 1 and 2 was acceptable. Furthermore, compared to the weight of the Comparative Example, Examples 1 and 2 did not require adhesive bonding, the first pressure was a fluctuating pressure, and the microporous layers of the injected semi-finished products of Examples 1 and 2 had micropores, allowing for significant weight reductions in Examples 1 and 2, from 41 g for the Comparative Example to 36 g and 35 g, respectively, a reduction of approximately 12% and 15%.

[0035] As can be seen from the above embodiments, the present invention has the following advantages. First, the variable pressure control injection method of the present invention applies a first pressure and a second pressure to a first foam material, respectively. The first pressure is a variable pressure, and therefore an injected semi-finished product having a microporous layer and a solidified layer can be obtained, with the microporous layer and the solidified layer having different foaming degrees. Second, the coinjection component manufacturing method of the present invention heats an injected semi-finished product having a microporous layer and a solidified layer and a second foam material under a stable internal pressure until complete foaming occurs to obtain a coinjection component. This allows for the formation of a coinjection component in which different materials are tightly bonded without the addition of an adhesive. The connection between the first material, which is fully foamed by the first foam material, and the second material, which is fully foamed by the second foam material, is smooth and aesthetically pleasing, creating a one-piece molding effect in the coinjection component and effectively reducing production costs. Furthermore, the bonding strength between the first and second materials in the coinjection component is significantly superior to that of a comparative example in which bonding is performed with an adhesive. Third, the microporous layer in the injected semi-finished product produced by the variable pressure control injection method of the present invention has micropores, so when it is later used in the co-injection component manufacturing method of the present invention, the weight of the co-injection component produced can be significantly reduced, achieving a lightweight effect.

[0036] Although the present invention has been disclosed in the above embodiments, they are not used to limit the present invention, and any person skilled in the art can make various modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined based on what is defined by the claims attached below. [Explanation of symbols]

[0037] 100: Variable pressure control injection method 110, 120, 130: Process 200: First variable pressure mold 210: Variable pressure porous layer 211: Variable pressure pore 212: Cooling pipe 220: Mold body 221: Solid layer 222: Bass 300: Second variable pressure mold 310: Variable pressure porous layer 311: Variable pressure pore 312: Cooling pipe 320: Mold body 321: Solid layer 322: Bass 400: Injection molding system 401: Foam-molded space 500: Injection semi-finished products 510: Microporous layer 520: Solidified layer 600: Manufacturing method for coinjection parts 610, 620, 630: Process 700: Co-injection material 710: 1st material 720:Second material P: First pressure

Claims

1. providing an injection molding system including a first variable pressure mold and a second variable pressure mold disposed opposite to each other and corresponding to a foam molding space; injecting a first foaming material into the foam molding space; a foaming step in which the first variable pressure mold applies a first pressure to the first foam material, the second variable pressure mold applies a second pressure to the first foam material, and the first foam material is heated and foamed as an injected semi-finished product, the first pressure and the second pressure are not the same, and the first pressure is a variable pressure; Equipped with The first variable pressure mold and the second variable pressure mold each include: A mold body; a variable pressure porous layer provided in the mold body, correspondingly exposed to the foam molding space, and having a plurality of variable pressure pores communicating with the foam molding space.

2. 2. The variable pressure control injection method according to claim 1, wherein the size of each of the plurality of variable pressure holes of the first variable pressure mold is 200 μm to 700 μm, and the size of each of the plurality of variable pressure holes of the second variable pressure mold is 200 μm to 700 μm.

3. 2. The variable pressure control injection method according to claim 1, wherein the first pressure is increased to a fourth pressure greater than the third pressure after a third pressure is continuously applied for 1 to 5 seconds.

4. 2. The variable pressure control injection method according to claim 1, wherein a fifth pressure is applied as the first pressure for 1 to 5 seconds, and then the fifth pressure is reduced to a sixth pressure that is lower than the fifth pressure.

5. The variable pressure control injection method according to claim 1 , wherein the second pressure is a fixed pressure.

6. The variable pressure control injection method according to claim 1 , wherein the first foam material is a rubber foam material.

7. 7. An injected semi-finished product manufactured by the variable pressure control injection method according to claim 1, wherein an end of the injected semi-finished product closer to the first variable pressure mold is a microporous layer, and an end of the injected semi-finished product closer to the second variable pressure mold is a solidified layer.

8. 8. The injection-molded semi-finished product according to claim 7, wherein the microporous layer has a foaming degree of 30% to 80%, and the solidified layer has a foaming degree of 50% to 100%.

9. Providing an injected semi-finished product according to claim 7; injecting a second foam material into the microporous layer of the injected blank to obtain a coinjected component precursor; a molding step of heating the coinjection component precursor under a stable internal pressure until it is completely foamed to obtain a coinjection component; A method for manufacturing a coinjection member comprising:

10. The method of claim 9, wherein the second foam material is a thermoplastic material.

Images