Supercritical cold press molding preparation method of shoe and foot bed and shoe and foot bed

Abstract

The invention relates to a supercritical cold press molding preparation method of a shoe and foot bed and the shoe and foot bed, the method comprises the following steps: a sheet A and a sheet B are prepared, the sheet B is a supercritical foaming sheet, and the hardness of the sheet B is greater than that of the supercritical foaming sheet; preparing a mold; the sheet A and the sheet B are separately put into an oven to be baked to reach a soft state; the supercritical foaming sheet and a sheet B are attached and placed in a mold, the sheet B is placed on the surface of a cavity of a lower mold to form a stable layer, and cold pressing treatment is conducted on the mold after mold closing; after cold pressing is completed, the mold is opened, a finished product is taken out, the cold-press-formed supercritical shoe bed is obtained after arrangement, the bottom face of the supercritical shoe bed is a sheet B, and the remaining foot contact face and the exposed part are supercritical foaming sheets. According to the invention, cold press molding is adopted, so that the mold and production cost of small and large supercritical membrane blanks are saved, the production process and mold pressing time are reduced, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to a shoe foot bed, in particular to a supercritical cold pressing preparation method of the shoe foot bed and the shoe foot bed. Background Art

[0002] Traditional shoe bed fabrication using supercritical foam sheet requires a mold to produce a small finished product. This finished product is then foamed into the shoe bed mold using a pressure autoclave. After polishing, the mold is placed in a secondary molding die for secondary heat softening and shaping, followed by cooling to finalize the shape. This entire process utilizes hot pressing, resulting in numerous steps and high costs. Furthermore, existing molds typically consist of a lower and upper die, each filled with a foam sheet, which can easily deform after molding. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a supercritical cold pressing method for preparing a shoe foot bed and a shoe foot bed.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A supercritical cold pressing method for preparing a shoe foot bed comprises the following steps:

[0006] Prepare sheet A and sheet B, wherein sheet A is a supercritical foam sheet and sheet B has a hardness greater than that of the supercritical foam sheet;

[0007] Prepare a mold, which has an upper mold, a middle frame and a lower mold, and cut the B sheet and the supercritical foam sheet into a shape that matches the cavity in the mold;

[0008] Place sheet B and supercritical foam sheet separately in an oven and bake them until they become soft;

[0009] The supercritical foam sheet and sheet B are laminated and then placed in a mold, wherein sheet B is placed on the cavity surface of the lower mold to form a stable layer. The upper mold presses the supercritical foam sheet from top to bottom, and the middle frame presses the supercritical foam sheet from the side. After the mold is closed, the mold is cold-pressed to keep the mold temperature below 0 and the cold-pressing time is greater than 100 seconds;

[0010] After the cold pressing is completed, the mold is opened and the finished product is taken out. After finishing, a cold-pressed supercritical shoe bed is obtained. The bottom surface of the supercritical shoe foot bed is sheet B, and the remaining foot contact surface and exposed part are supercritical foam sheet.

[0011] As a further improvement, the B sheet is an EVA sheet or cloth.

[0012] As a further improvement, the density of the supercritical foamed sheet is 0.11-0.18G / C㎡, and the hardness is 30-40 degrees; the density of the EVA sheet is 0.18-0.28G / C㎡, and the hardness is 45-55 degrees.

[0013] As a further improvement, the hot melt adhesive is a non-traceable hot melt adhesive film with a melting point of 120-160°C.

[0014] As a further improvement, the temperature of the supercritical foamed sheet is maintained at 160-180° C. for 120-180 seconds during baking, and the temperature of the B sheet is maintained at 160-180° C. for 40-120 seconds during baking.

[0015] As a further improvement, the thickness of the supercritical foamed sheet is greater than the thickness of the B sheet.

[0016] As a further improvement, the EVA sheet is provided with a plurality of through holes.

[0017] A shoe footbed includes a footbed body and a stabilizing layer, wherein the footbed body is cold-pressed by a supercritical foam sheet, the stabilizing layer is formed by an EVA sheet or cloth, and the stabilizing layer is covered with hot melt adhesive, and the stability is fixed to the footbed body by the hot melt adhesive.

[0018] The present invention has the following beneficial technical effects:

[0019] By using a material with higher hardness as the stabilizing layer on the bottom of the footbed, the swelling and deformation problems of the bottom can be effectively improved during the molding process. Cold pressing is used to reduce deformation caused by hot pressing, saving the mold and production costs of the supercritical membrane embryo, reducing the production process and molding time, and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic cross-sectional view of the mold forming of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0022] In the description of the present invention, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like are used to indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0023] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, removable connections, or integral connections. They may refer to mechanical connections or electrical connections. They may refer to direct connections or indirect connections through an intermediary, and they may refer to internal communication between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0024] Example 1

[0025] like Figure 1 As shown, a supercritical cold pressing method for preparing a shoe foot bed comprises the following steps:

[0026] Prepare sheet A and sheet B, wherein sheet A is a supercritical foam sheet 3 , sheet B has a hardness greater than that of the supercritical foam sheet, and sheet B is an EVA sheet 4 .

[0027] Prepare a mold, which has an upper mold 1, a middle frame 2 and a lower mold 5, and cut the EVA sheet and the supercritical foam sheet into a shape matching the cavity in the mold.

[0028] The EVA sheet and the supercritical foam sheet are placed in an oven and baked separately to reach a soft state. The temperature of the supercritical foam sheet is maintained at 160-180°C for 120-180 seconds during baking, and the temperature of the B sheet is maintained at 160-180°C for 40-120 seconds during baking.

[0029] The supercritical foam sheet and sheet B are laminated and then placed in a mold, wherein the EVA sheet is placed on the cavity surface of the lower mold to form a stabilizing layer. The upper mold presses the supercritical foam sheet from top to bottom, and the middle frame presses the supercritical foam sheet from the side. After the mold is closed, the mold is cold-pressed to keep the mold temperature below 0 and the cold-pressing time is greater than 100 seconds;

[0030] After the cold pressing is completed, the mold is opened and the finished product is taken out. After finishing, a cold-pressed supercritical shoe bed is obtained. The bottom surface of the supercritical shoe foot bed is EVA sheet, and the remaining foot contact surface and exposed part are supercritical foam sheet.

[0031] Supercritical foam sheet refers to a lightweight, elastic material produced through a supercritical fluid physical foaming process, using nitrogen or carbon dioxide as the foaming agent. Cold pressing involves pressure forming below the material's phase transition temperature, using a refrigeration cycle to maintain a low mold temperature and prevent dimensional deviations caused by thermal expansion.

[0032] Specifically, the preparation process first independently bakes the two sheets to a suitable processing state, in which the foaming material requires a longer softening time to ensure molding ductility. During the mold assembly stage, the high-hardness EVA sheet is precisely placed on the surface of the lower mold cavity to form a stable layer, which plays a supporting role, and the supercritical foaming sheet covers it to form a contact interface. During the mold closing process, the upper mold applies vertical pressure to make the materials fit tightly, and the middle frame simultaneously applies lateral restraint force to prevent edge warping. During the continuous low-temperature pressing process, material layers of different hardness are bonded at the interface through intermolecular forces, eventually forming an integrated structure with gradient mechanical properties.

[0033] The supercritical foamed sheet has a density of 0.11-0.18 G / cm2 and a hardness of 30-40 degrees; the EVA sheet has a density of 0.18-0.28 G / cm2 and a hardness of 45-55 degrees.

[0034] The density and hardness of the supercritical foam sheet are set to be lower than those of the EVA sheet. For example, the density of the foam sheet can be 0.15G / C㎡ and the hardness can be 35 degrees, while the density of the EVA sheet can be 0.22G / C㎡ and the hardness can be 50 degrees. During the cold pressing process, the two materials form a gradient support structure due to the difference in hardness: the EVA sheet provides rigid support as a stabilizing layer, and the supercritical foam sheet absorbs impact as a contact layer. By precisely controlling the density and hardness parameters, the two materials can achieve interface fusion under low temperature conditions, avoiding interlayer separation caused by differences in thermal expansion coefficients. By increasing the density of the EVA sheet, the problem of swelling when sticking to the bottom can be effectively solved.

[0035] By limiting the density and hardness range of the two materials, the stabilizing layer and the buffer layer can form a stable composite structure under low temperature conditions, and the finished product can be finalized without the need for secondary hot pressing.

[0036] The hot melt adhesive is a non-traceable hot melt adhesive film with a melting point of 120-160°C. This non-traceable hot melt adhesive film is a material that solidifies upon melting to form a stable adhesive layer and does not soften or flow again at subsequent processing temperatures. Specifically, a hot melt adhesive film based on ethylene-vinyl acetate copolymer can be used. This property prevents secondary softening of the adhesive layer due to temperature fluctuations during the cold pressing process, which can lead to adhesive failure.

[0037] The melting point of 120-160°C refers to the temperature range in which the hot melt adhesive reaches a completely molten state during the bonding process. This can be achieved by adjusting the polymer segment composition and cross-linking degree of the hot melt adhesive. For example, a hot melt adhesive film prepared from a modified polyolefin material can achieve sufficient adhesion between sheet B and the supercritical foamed sheet within this temperature range while avoiding damage to the sheet structure due to excessively high temperature.

[0038] Specifically, during the lamination process between sheet B and the supercritical foam sheet, the hot melt adhesive film melts during the baking phase, forming a uniform bonding interface. Due to the hot melt adhesive's non-traceability, the adhesive layer remains solid even when the mold temperature drops below 0°C during the subsequent cold pressing process, avoiding the interlaminar displacement caused by creep of traditional reversible hot melt adhesives under low-temperature pressure. Furthermore, a controlled melting point range of 120-160°C ensures effective melting in line with the sheet baking temperature while preventing excessive softening and deformation of the sheet due to high temperatures.

[0039] Compared to existing technologies, traditional methods using traceable hot melt adhesives can cause the adhesive layer to soften due to temperature fluctuations during the cold pressing process, leading to a decrease in interlayer bond strength or localized debonding. This solution, however, leverages the curing stability of non-traceable hot melt adhesives, combined with a precisely controlled melting point range, to maintain bond strength while eliminating the impact of the cold pressing process on the adhesive layer's condition.

[0040] This application solves the problem of interlayer separation caused by the softening of hot melt adhesive during the cold pressing process of the existing shoe foot bed, ensures the reliability of the interface bonding between the B sheet and the supercritical foam sheet, and at the same time avoids the deformation defects of the finished product caused by the thermal traceability of the adhesive layer, significantly improving the product yield.

[0041] The thickness of the supercritical foam sheet is greater than that of sheet B. According to the thickness of the foot bed, such as 15 mm, the thickness of the supercritical foam sheet is selected to be 11-13 mm, and the thickness of the EVA sheet is 2-4 mm. The overall thickness is uniform, and when cutting, the periphery needs to be larger.

[0042] During the cold press molding process, thicker supercritical foam sheets undergo greater volume deformation when under pressure in the mold. The porous structure of the supercritical foam sheet itself undergoes directionally compression under low temperature conditions, forming a three-dimensional shape that matches the contours of the foot. Due to its thinness and high hardness, the EVA sheet preferentially contacts the lower mold surface during the mold closing process to form a stable base, limiting the lateral flow of the foam material. After the thickness ratio of the two materials is matched, the compression margin of the foam sheet can completely fill the mold cavity, avoiding surface depression defects caused by insufficient material. At the same time, the rigid base of the EVA sheet can offset the shrinkage stress of the foam material during the cooling process, preventing deformation and also solving the problem of subsequent swelling of the bottom.

[0043] In addition, the EVA sheet is provided with a plurality of through holes, which helps to improve the exhaust effect and solve the problem of air swelling.

[0044] A shoe footbed includes a footbed body and a stabilizing layer, wherein the footbed body is cold-pressed by a supercritical foam sheet, the stabilizing layer is formed by an EVA sheet or cloth, and the stabilizing layer is covered with hot melt adhesive, and the stability is fixed to the footbed body by the hot melt adhesive.

[0045] Example 2

[0046] A supercritical cold pressing method for preparing a shoe foot bed comprises the following steps:

[0047] Prepare sheet A and sheet B, wherein sheet A is a supercritical foam sheet, sheet B has a hardness greater than that of the supercritical foam sheet, and sheet B is a shaped cloth.

[0048] Prepare a mold, which has an upper mold, a middle frame and a lower mold, and cut the A-shaped cloth and the supercritical foam sheet into a shape matching the cavity in the mold.

[0049] The shaped cloth and the supercritical foam sheet are placed in an oven and baked separately to reach a soft state. The temperature of the supercritical foam sheet is maintained at 160-180°C for 120-180 seconds during baking, and the temperature of the shaped cloth is maintained at 160-180°C for 40-120 seconds during baking.

[0050] The supercritical foam sheet is laminated with the shaping cloth and then placed into the mold, wherein the shaping cloth is arranged on the cavity surface of the lower mold to form a stabilizing layer, the upper mold presses the supercritical foam sheet from top to bottom, and the middle frame presses the supercritical foam sheet from the side. After the mold is closed, the mold is cold-pressed to make the mold temperature below 0 and the cold-pressing time is greater than 100 seconds.

[0051] After the cold pressing is completed, the mold is opened and the finished product is taken out. After finishing, a cold-pressed supercritical shoe bed is obtained. The bottom surface of the supercritical shoe foot bed is sheet B, and the remaining foot contact surface and exposed part are supercritical foam sheet.

[0052] The difference between the second embodiment and the first embodiment is that a shaped cloth is used as the stabilizing layer.

[0053] It should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A supercritical cold pressing method for preparing a shoe foot bed, characterized in that: The following steps are involved: Prepare sheet A and sheet B, wherein sheet A is a supercritical foam sheet and sheet B has a hardness greater than that of the supercritical foam sheet; Prepare a mold, which has an upper mold, a middle frame and a lower mold, and cut the B sheet and the supercritical foam sheet into a shape that matches the cavity in the mold; Place sheet B and supercritical foam sheet separately in an oven and bake them until they become soft; The supercritical foam sheet and sheet B are laminated and then placed in a mold, wherein sheet B is placed on the cavity surface of the lower mold to form a stable layer. The upper mold presses the supercritical foam sheet from top to bottom, and the middle frame presses the supercritical foam sheet from the side. After the mold is closed, the mold is cold-pressed to keep the mold temperature below 0 and the cold-pressing time is greater than 100 seconds; After the cold pressing is completed, the mold is opened and the finished product is taken out. After finishing, a cold-pressed supercritical shoe bed is obtained. The bottom surface of the supercritical shoe foot bed is sheet B, and the remaining foot contact surface and exposed part are supercritical foam sheet.

2. The supercritical cold pressing method for preparing a shoe foot bed according to claim 1, characterized in that: The B sheet is an EVA sheet or a cloth.

3. The method for preparing the shoe foot bed by supercritical cold pressing according to claim 2, characterized in that: The supercritical foamed sheet has a density of 0.11-0.18 G / cm2 and a hardness of 30-40 degrees; the EVA sheet has a density of 0.18-0.28 G / cm2 and a hardness of 45-55 degrees.

4. The method for preparing the shoe foot bed by supercritical cold pressing according to claim 2, characterized in that: The hot melt adhesive is a non-traceable hot melt adhesive film with a melting point of 120-160°C.

5. The supercritical cold pressing method for preparing a shoe foot bed according to claim 2, characterized in that: The temperature of the supercritical foamed sheet is maintained at 160-180° C. for 120-180 seconds during baking, and the temperature of the B sheet is maintained at 160-180° C. for 40-120 seconds during baking.

6. The method for preparing the shoe foot bed by supercritical cold pressing according to claim 2, characterized in that: The thickness of the supercritical foamed sheet is greater than that of the B sheet.

7. The method for preparing the shoe foot bed by supercritical cold pressing according to claim 2, characterized in that: The EVA sheet is provided with a plurality of through holes.

8. A shoe foot bed prepared according to the method of any one of claims 1 to 7, characterized in that: It includes a foot bed body and a stabilizing layer, wherein the foot bed body is cold-pressed by supercritical foaming sheet, the stabilizing layer is formed by EVA sheet or cloth, and the stabilizing layer is covered with hot melt adhesive, and the stability is fixed to the foot bed body by the hot melt adhesive.

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