Variable-pressure controlled injection method, injected semi-finished product, and co-injected part manufacturing method

Abstract

Provided in the present invention are a variable-pressure controlled injection method, an injected semi-finished product, and a co-injected part manufacturing method. The variable-pressure controlled injection method comprises: providing an injection molding system, injecting a first foaming material, and performing a foaming step, wherein the injection molding system comprises a first variable-pressure mold and a second variable-pressure mold, and in the foaming step, the first variable-pressure mold and the second variable-pressure mold respectively apply a first pressure and a second pressure to the first foaming material, and heat the first foaming material to foam into an injected semi-finished product, wherein the first pressure is a variable pressure. Therefore, the obtained injected semi-finished product has a microporous layer and a cured layer, and the injected semi-finished product and a second foaming material can be further subjected to a molding step and are heated under a stable internal pressure until same are fully foamed, so as to obtain a co-injected part.

Description

Methods for controlling injection molding, manufacturing of injection-molded semi-finished products and co-injected parts Technical Field

[0001] This invention relates to an injection method, a method for manufacturing injection semi-finished products and co-injected parts, and particularly to a variable pressure controlled injection method, a method for manufacturing injection semi-finished products and co-injected parts. Background Technology

[0002] Shoes are primarily used to protect the feet from being injured by sharp objects when stepping on the ground. Shoes typically consist of an upper and a sole. The upper can be made of any suitable material to cover, secure, and support the foot to the sole. The sole is usually a layered structure extending between the ground surface and the upper, including an outsole that provides abrasion resistance and traction to the ground, and a midsole positioned between the outsole and the upper.

[0003] The outsole, needing to provide slip resistance, abrasion resistance, and elasticity, is typically made of materials such as rubber or genuine leather to enhance traction with the ground surface. The midsole, to provide cushioning for the foot, is usually at least partially made of polymer foam. Under load, the polymer foam can elastically compress to cushion the force on the foot by reducing the ground reaction force. In conventional manufacturing processes, the midsole and outsole of the shoe sole structure undergo roughing, washing, drying, surface treatment, drying, gluing, and further drying before being joined together. However, because the outsole and midsole are made of different materials, and these dissimilar materials have varying degrees of elasticity, hardness, or density, conventional shoe sole structures suffer from problems such as poor lifespan, easy damage, and the outsole easily detaching from the midsole.

[0004] Furthermore, the volatile organic compounds commonly used in the gluing process of shoe sole construction can easily cause harm to human health and the environment. Therefore, developing a method to tightly bond heterogeneous materials in the shoe sole structure without adding adhesives is a commercially viable development goal.

[0005] Summary of the Invention

[0006] One objective of this invention is to provide a variable pressure controlled injection method, which applies a first pressure and a second pressure to a first foaming material during the foaming step. Since the first pressure and the second pressure are different and the first pressure is a variable pressure, an injection semi-finished product with a microporous layer and a cured layer can be obtained.

[0007] Another objective of this invention is to provide a method for manufacturing co-injected parts, wherein a semi-finished injection product having a microporous layer and a cured layer is heated with a second foaming material under stable internal pressure until it is fully foamed to obtain a co-injected part, which can form a co-injected part with a tight bond of heterogeneous materials without adding an adhesive.

[0008] One embodiment of the present invention provides a variable pressure controlled injection method, comprising the following steps: An injection molding system is provided, comprising a first variable pressure mold and a second variable pressure mold, the first and second variable pressure molds being disposed opposite each other in a foaming molding space, and the first and second variable pressure molds each comprising a mold body and a variable pressure porous layer, the variable pressure porous layer being disposed on the mold body and correspondingly exposed in the foaming molding space, the variable pressure porous layer having a plurality of variable pressure pores communicating with the foaming molding space; injecting a first foaming material into the foaming molding space; and performing a foaming step, wherein the first variable pressure mold applies a first pressure to the first foaming material, and the second variable pressure mold applies a second pressure to the first foaming material, and the first foaming material is heated to foam into an injection semi-finished product, wherein the first pressure and the second pressure are different, and the first pressure is a variable pressure.

[0009] According to the aforementioned variable pressure controlled injection method, the size of each variable pressure orifice of the first variable pressure mold can be 200 micrometers to 700 micrometers, and the size of each variable pressure orifice of the second variable pressure mold can be 200 micrometers to 700 micrometers.

[0010] According to the aforementioned variable pressure control injection method, the first pressure can be a third pressure applied for 1 to 5 seconds and then increased to a fourth pressure, wherein the third pressure is less than the fourth pressure.

[0011] According to the aforementioned variable pressure control injection method, the first pressure can be a fifth pressure applied for 1 to 5 seconds and then reduced to a sixth pressure, wherein the fifth pressure is greater than the sixth pressure.

[0012] According to the aforementioned variable pressure controlled injection method, the second pressure can be a fixed pressure.

[0013] According to the aforementioned variable pressure controlled injection method, the first foaming material can be a rubber-plastic foaming material.

[0014] Another embodiment of the present invention provides an injection semi-finished product, which is obtained by the pressure-controlled injection method described above, wherein the end of the injection semi-finished product near the first pressure mold is a microporous layer, and the end of the injection semi-finished product near the second pressure mold is a cured layer.

[0015] Based on the aforementioned injection-molded semi-finished product, the degree of foaming of the microporous layer can be 30% to 80%, and the degree of foaming of the cured layer can be 50% to 100%.

[0016] Another embodiment of the present invention provides a method for manufacturing a co-injection part, comprising the following steps: providing an injection semi-finished product as described above; injecting a second foaming material onto the microporous layer of the injection semi-finished product to obtain a co-injection part precursor; and performing a molding step of heating the co-injection part precursor under a stable internal pressure until it is fully foamed to obtain a co-injection part.

[0017] According to the aforementioned co-injection part manufacturing method, the second foaming material can be a thermoplastic material.

[0018] Therefore, the variable pressure controlled injection method of the present invention can obtain an injection semi-finished product with a microporous layer and a cured layer by controlling the pressure of the foaming step. Then, by using the co-injection part manufacturing method of the present invention, the first material after the first foaming material is fully foamed and the second material after the second foaming material is fully foamed can be tightly bonded without adding an adhesive. Attached Figure Description

[0019] To make the above and other objects, features, advantages and embodiments of the present invention more apparent and understandable, the accompanying drawings are described below:

[0020] Figure 1 illustrates a flowchart of the steps of a variable pressure controlled injection method according to an embodiment of the present invention;

[0021] Figure 2 illustrates a process diagram of the foaming step in the variable pressure controlled injection method of Figure 1.

[0022] Figure 3 shows a partial schematic diagram of the foaming step in the variable pressure controlled injection method of Figure 1;

[0023] Figure 4 illustrates a schematic diagram of an injection-molded semi-finished product according to another embodiment of the present invention;

[0024] Figure 5 illustrates a flowchart of a co-injection part manufacturing method according to another embodiment of the present invention;

[0025] Figure 6 illustrates a schematic diagram of a co-ejected part manufactured by a co-ejection part manufacturing method according to another embodiment of the present invention; and

[0026] Figure 7 shows a cross-sectional view of the co-injection part of Figure 6 along section line 7-7.

[0027] [Symbol Explanation]

[0028] 100: Variable Pressure Controlled Injection Method

[0029] 110, 120, 130: Steps

[0030] 200: First transformer mold

[0031] 210: Transformer porous layer

[0032] 211: Transformer porosity

[0033] 212: Cooling pipe

[0034] 220: Mold body

[0035] 221: Solid layer

[0036] 222: Base

[0037] 300: Second transformer mold

[0038] 310: Transformer porous layer

[0039] 311: Transformer porosity

[0040] 312: Cooling pipe

[0041] 320: Mold body

[0042] 321: Solid layer

[0043] 322: Base

[0044] 400: Injection Molding System

[0045] 401: Foaming Molding Space

[0046] 500: Injection of semi-finished products

[0047] 510: Microporous layer

[0048] 520: Curing layer

[0049] 600: Co-injection molding method

[0050] 610, 620, 630: Steps

[0051] 700: Co-injection part

[0052] 710: First Material

[0053] 720: Second Material

[0054] P: First pressure Detailed Implementation

[0055] Several embodiments of the present invention will now be described with reference to the accompanying drawings. For clarity, many practical details will be set forth in the following description. However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not essential. Furthermore, for the sake of simplicity in the drawings, some conventional structures and elements will be illustrated in a simplified schematic manner.

[0056] It should be noted that certain terms in the specification and claims of this invention are preceded by "first", "second", "third", "fourth", "fifth" or "sixth" to distinguish them from each other. Unless otherwise specified, or if the order of the terms is not apparent from the context, the order of the terms is not restricted by the prefixes "first", "second", "third", "fourth", "fifth" or "sixth".

[0057] Please refer to Figures 1, 2, 3, and 4 together. Figure 1 shows a flowchart of the steps of a variable pressure controlled injection method 100 according to one embodiment of the present invention. Figure 2 shows a schematic diagram of the foaming step in the variable pressure controlled injection method 100 of Figure 1. Figure 3 shows a partial schematic diagram of the foaming step in the variable pressure controlled injection method 100 of Figure 1. Figure 4 shows a schematic diagram of an injection-produced semi-finished product 500 according to another embodiment of the present invention. In Figure 1, the variable pressure controlled injection method 100 includes steps 110, 120, and 130.

[0058] Step 110 involves providing an injection molding system 400, which includes a first variable pressure mold 200 and a second variable pressure mold 300. The first variable pressure mold 200 and the second variable pressure mold 300 are positioned opposite each other in the foaming molding space 401. The first variable pressure mold 200 includes a mold body 220 and a variable pressure porous layer 210. The variable pressure porous layer 210 is disposed on the mold body 220 and exposed in the foaming molding space 401. The variable pressure porous layer 210 has a plurality of variable pressure pores 211, which are connected to the foaming molding space 401. Cooling pipes 212 may be embedded in the variable pressure porous layer 210. The second pressure-changing mold 300 includes a mold body 320 and a pressure-changing porous layer 310. The pressure-changing porous layer 310 is disposed on the mold body 320 and correspondingly exposed in the foaming molding space 401. The pressure-changing porous layer 310 has a plurality of pressure-changing pores 311, which are connected to the foaming molding space 401. Cooling pipes 312 may be embedded in the pressure-changing porous layer 310. The size of each pressure-changing pore 211 in the first pressure-changing mold 200 can be from 200 micrometers (μm) to 700 micrometers, and the pressure-changing pores 211 can be distributed in a non-equidistant mesh pattern or arranged in equidistant parallel patterns. The size of each pressure-changing pore 311 in the second pressure-changing mold 300 is from 200 micrometers to 700 micrometers, and the pressure-changing pores 311 can be distributed in a non-equidistant mesh pattern or arranged in equidistant parallel patterns. The first transformer mold 200 has a mold body 220 comprising a solid layer 221 and a base 222, with the solid layer 221 disposed inside the base 222 and the transformer porous layer 210 disposed inside the solid layer 221. The second transformer mold 300 has a mold body 320 comprising a solid layer 321 and a base 322, with the solid layer 321 disposed inside the base 322 and the transformer porous layer 310 disposed inside the solid layer 321.

[0059] Step 120 involves injecting the first foaming material into the foaming molding space 401. The first foaming material can be a rubber-plastic foaming material, such as thermoplastic polyurethane (TPU), ethylene vinyl acetate (EVA), synthetic rubber, thermoplastic elastomer (TPE), thermoplastic vulcanizates (TPV), thermoplastic polyester elastomer (TPEE), polyether block amide (PEBAX), TPU / TPV, TPV / TPU / rubber, or TPEE / TPV.

[0060] Step 130 involves a foaming process. A first pressure P is applied to the first foaming material by a first variable pressure mold 200, and a second pressure P is applied to the first foaming material by a second pressure mold 300. The first foaming material is heated to foam into an injection-molded semi-finished product 500. The first pressure P and the second pressure are different, and the first pressure P is a variable pressure. More specifically, the first pressure P can 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, wherein the third pressure is less than the fourth pressure, and the fifth pressure is greater than the sixth pressure. Preferably, the third pressure can be 5 bar to 30 bar, and the fourth pressure can be 10 bar to 90 bar. For example, a third pressure of 5 bar is applied for 1 to 5 seconds and then increased to a fourth pressure of 60 bar. The fifth pressure can be 10 bar to 90 bar, and the sixth pressure can be 5 bar to 30 bar. For example, a fifth pressure of 30 bar is applied for 1 to 5 seconds and then decreased to a sixth pressure of 5 bar. Because the first pressure P applied by the first variable pressure mold 200 is a variable pressure, it affects the foaming degree of the first foaming material, thereby forming a microporous layer 510 at the end of the injection-molded semi-finished product 500 near the first variable pressure mold 200. The foaming degree of the microporous layer 510 can be 30% to 80%, and the first pressure P can be adjusted according to the desired foaming degree. The second pressure can be a fixed pressure, preferably 5 bar to 80 bar. Because the second pressure applied by the second variable pressure mold 300 is a fixed pressure, the first foaming material can be foamed stably. Therefore, a cured layer 520 is formed at the end of the injection-molded semi-finished product 500 near the second variable pressure mold 300, wherein the foaming degree of the cured layer 520 can be 50% to 100%.

[0061] Furthermore, the second pressure applied by the second variable pressure mold 300 can also be a variable pressure, which can cause the end of the injection semi-finished product 500 near the second variable pressure mold 300 to also be in a state of lower foaming degree. And the second pressure can be adjusted according to the desired foaming degree.

[0062] Please refer to Figures 5, 6, and 7 together. Figure 5 shows a flowchart of the steps of a co-injection molding method 600 according to another embodiment of the present invention. Figure 6 shows a schematic diagram of a co-injection molded part 700 obtained by the co-injection molding method 600 according to another embodiment of the present invention. Figure 7 shows a cross-sectional schematic diagram of the co-injection molded part 700 of Figure 6 along section line 7-7. In Figure 5, the co-injection molding method 600 includes steps 610, 620, and 630.

[0063] Step 610 is to provide an injection-molded semi-finished product 500, which includes a microporous layer 510 and a curing layer 520, wherein the degree of foaming of the microporous layer 510 can be 30% to 80%, and the degree of foaming of the curing layer 520 can be 50% to 100%.

[0064] Step 620 involves injecting a second foaming material onto the microporous layer 510 of the injection-molded semi-finished product 500 to obtain a co-injected precursor. The second foaming material can be a thermoplastic material, such as thermoplastic polyurethane (TPU), thermoplastic polyester elastomer (TPEE), or polyether block amide (PEBAX).

[0065] Step 630 is a molding step in which the co-injection part precursor is heated under stable internal pressure until it is fully foamed to obtain the co-injection part 700. Specifically, the co-injection part precursor is heated to 30°C to 100°C under a stable internal pressure ranging from 10 bar to 90 bar to fully foam it. Because the microporous layer 510 of the injection semi-finished product 500 contains incompletely foamed bubbles and micropores, the contact surface between the microporous layer 510 and the second foaming material has a roughening effect. This allows the second foaming material to dissolve into the microporous layer 510 of the injection semi-finished product 500 after heating and undergo secondary foaming. Therefore, the first material 710 after the first foaming material is fully foamed and the second material 720 after the second foaming material is fully foamed can be tightly bonded without the need for adhesive bonding to obtain the co-injection part 700.

[0066] As shown in Figures 6 and 7, the co-injected component 700 can be a shoe material, with the first material 710 being the outsole and the second material 720 being the midsole. The shoe material produced by the co-injection manufacturing method 600 allows the outsole and midsole to be tightly bonded, thereby improving the problem of the outsole easily detaching from the midsole and mitigating the environmental pollution caused by the use of chemical solvents and the consumption of large amounts of water in the roughing and gluing processes of the shoe sole structure. However, depending on the requirements, the first material 710 can also be the first midsole, and the second material 720 can be the second midsole. In addition, the co-injected component 700 may also include a third foaming material, or a carbon fiber plate or plastic plate may be included between the second foaming material and the injection-molded semi-finished product 500. The co-injection manufacturing method 600 of the present invention then wraps the carbon fiber plate or plastic plate between the first material 710 and the second material 720, for example, wrapping it in the middle layer of the midsole of the shoe material. The first material 710 and the second material 720 may be the same or different. This invention is not limited thereto.

[0067] <Experimental Example>

[0068] To demonstrate the bonding effect of the injection semi-finished product obtained by the variable pressure controlled injection method of the present invention on the first and second materials in the co-injection part obtained by the co-injection part manufacturing method of the present invention, TPV / TPU / rubber with a Shore hardness A of 60±3 was used as the first foaming material in the experiment, and foaming steps were performed with different first pressures to obtain injection semi-finished products of comparative example, example 1 and example 2. The first pressure of the injection semi-finished product of comparative example 1 was 1 atm. The first pressure applied to the injection semi-finished product of example 1 was a third pressure of 30 bar applied for 1 to 5 seconds, and then increased to a fourth pressure of 60 bar. The first pressure applied to the injection semi-finished product of example 2 was a fifth pressure of 60 bar applied for 1 to 5 seconds, and then decreased to a sixth pressure of 30 bar. A thermoplastic material with a Shore hardness C of 25 to 65 was used as the second foaming material and injected into the injection-molded semi-finished products of Comparative Example, Example 1, and Example 2, respectively. A molding process was then performed to obtain co-injected parts of Comparative Example, Example 1, and Example 2 (hereinafter referred to as Comparative Example, Example 1, and Example 2). In the Comparative Example, the first and second materials were bonded together with an adhesive. The bond strength of the first and second materials in Comparative Example, Example 1, and Example 2 was evaluated according to ASTM D186. Under ASTM D186, a 10mm wide test piece was used. A tensile force greater than or equal to 3.5 kg was considered acceptable. The test was conducted to observe whether the second material was torn apart by the first material. The second material had to tear for the bond strength to be considered acceptable. The test results are shown in Table 1 below.

[0069] Table 1

[0070] As shown in Table 1, the tensile strength values ​​of Examples 1 and 2 are both above 3.5–4.5 kg, significantly higher than those of the comparative example, indicating a tight bond between the first and second materials in Examples 1 and 2. Furthermore, material breakage was observed in Examples 1 and 2, while no material breakage was observed in the comparative example, indicating that the bonding strength between the first and second materials in Examples 1 and 2 is satisfactory. In addition, compared to the comparative example, Examples 1 and 2 do not require adhesive bonding, and because the first pressure is a variable pressure, the microporous layer of the injection-molded semi-finished products in Examples 1 and 2 has micropores. Therefore, the weight of Examples 1 and 2 can be significantly reduced, from 41 g in the comparative example to 36 g and 35 g respectively, representing reductions of approximately 12% and 15%.

[0071] As can be seen from the above embodiments, the present invention has the following advantages: First, the variable pressure controlled injection method of the present invention, by applying a first pressure and a second pressure to the first foaming material respectively, since the first pressure and the second pressure are different and the first pressure is a variable pressure, can obtain an injection-molded semi-finished product with a microporous layer and a cured layer, and the foaming degree of the microporous layer and the cured layer are different. Second, the co-injection part manufacturing method of the present invention, by heating the injection-molded semi-finished product with a microporous layer and a cured layer and a second foaming material under stable internal pressure until fully foamed, to obtain a co-injection part, can form a co-injection part with a tight bond between heterogeneous materials without adding an adhesive, and the connection between the first material after the first foaming material is fully foamed and the second material after the second foaming material is fully foamed is flat and beautiful, so that the co-injection part produces an integral molding effect and can effectively save production costs. In addition, the bonding strength between the first material and the second material in the co-injection part is significantly better than that of the comparative example bonded with an adhesive. Thirdly, the microporous layer in the injection semi-finished product produced by the variable pressure controlled injection method of the present invention has micropores. When subsequently applied to the co-injection part manufacturing method of the present invention, the weight of the obtained co-injection part can be greatly reduced, achieving the effect of lightweighting.

[0072] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art may make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A variable pressure controlled injection method, characterized in that, Comprising: Providing an injection molding system, comprising a first variable pressure mold and a second variable pressure mold, the first variable pressure mold and the second variable pressure mold being oppositely arranged corresponding to a foaming molding space, and the first variable pressure mold and the second variable pressure mold respectively comprising: a mold body; and a variable pressure porous layer arranged on the mold body and corresponding to being exposed to the foaming molding space, the variable pressure porous layer being provided with a plurality of variable pressure pores, the plurality of variable pressure pores being connected to the foaming molding space; injecting a first foaming material into the foaming molding space; and performing a foaming step, the first variable pressure mold applying a first pressure to the first foaming material, and the second variable pressure mold applying a second pressure to the first foaming material, and heating the first foaming material to foam into an injection semi-product, wherein the first pressure and the second pressure are not the same, and the first pressure is a variable pressure.

2. The variable pressure injection method of claim 1, wherein A size of each of the plurality of variable pressure pores of the first variable pressure mold is 200 microns to 700 microns, and a size of each of the plurality of variable pressure pores of the second variable pressure mold is 200 microns to 700 microns.

3. The variable pressure injection method of claim 1, wherein The first pressure is applied a third pressure for 1 second to 5 seconds and then increased to a fourth pressure, the third pressure being less than the fourth pressure.

4. The variable pressure injection method of claim 1, wherein The first pressure is applied a fifth pressure for 1 second to 5 seconds and then decreased to a sixth pressure, the fifth pressure being greater than the sixth pressure.

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

6. The variable pressure injection method of claim 1, wherein The first foaming material is a rubber-plastic foaming material.

7. An injection preform, characterized in that, The injection semi-product is made by the variable pressure control injection method according to any one of claims 1 to 6, wherein an end of the injection semi-product close to the first variable pressure mold is a microporous layer, and an end of the injection semi-product close to the second variable pressure mold is a solidified layer.

8. An exit semi-finished product according to claim 7, characterized in that, A foaming degree of the microporous layer is 30% to 80%, and a foaming degree of the solidified layer is 50% to 100%.

9. A co-injection part manufacturing method characterized by, Comprising: Providing the injection semi-product according to claim 7; injecting a second foaming material onto the microporous layer of the injection semi-product to obtain a co-injection precursor; and performing a molding step, heating the co-injection precursor to completely foam under a stable internal pressure to obtain a co-injection product.

10. The co-shot part manufacturing method of claim 9, wherein, The second foaming material is a thermoplastic material.

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