Container and preparation process thereof

Abstract

The invention relates to a container and a preparation process thereof, the container comprises a base and a plurality of side plates assembled on the base, and the plurality of side plates define a space for accommodating articles; at least one side plate comprises a side plate body made of plastic, the side plate body comprises at least one thick-wall area and at least one thin-wall area, the thick-wall area is a local area of the side plate body, and the thin-wall area is the other area of the side plate body; the average porosity of the thick-wall area is larger than that of the thin-wall area, the thick-wall area comprises a compact area located on the surface layer and a foaming area located in the thick-wall area, and the average porosity of the compact area is smaller than that of the foaming area; the thick-wall area is locally enhanced through the internal foaming area, so that traditional reinforcing ribs do not need to be arranged, the surface of the container is kept smooth, and the problems that cleaning is difficult, dirt remains, and loaded objects are scraped and damaged are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of logistics container technology, specifically to a container and its manufacturing process. Background Technology

[0002] In modern logistics and supply chain systems, reusable plastic packaging containers, such as crates, pallets, and logistics boxes, play a crucial role. These containers are typically mass-produced using injection molding processes, and the materials are mostly polypropylene (PP), high-density polyethylene (HDPE), or copolymer polypropylene. To control material costs and component weight while ensuring sufficient structural strength, rigidity, and fatigue resistance under complex conditions such as stacking, handling, and transportation, traditional designs commonly employ a "reinforcing rib" structure.

[0003] Reinforcing ribs are typically rib-like protrusions designed on the inner or outer surfaces of container walls (such as side panels and bottom plates), extending perpendicularly to or at a certain angle to the main wall surface. By rationally arranging a network of crisscrossing reinforcing ribs, the moment of inertia of the plate-like structure can be greatly increased, thus achieving significant rigidity enhancement with a relatively small increase in material weight. This is a classic method for lightweight design of engineering plastic products. However, crisscrossing grooves, trenches, or grid-like gaps inevitably form between the reinforcing ribs. These areas easily accumulate dust, oil, product residues (such as food crumbs and chemical dust), and microorganisms. Conventional cleaning methods (such as high-pressure water jet washing and soaking) are insufficient to thoroughly remove dirt from these deep and narrow grooves, often requiring manual scrubbing or more complex cleaning processes, increasing operating costs and downtime.

[0004] Furthermore, in some large containers, hollow air channels are formed within the thick-walled areas of the product, which can significantly save on material, reduce weight, and minimize shrinkage while maintaining strength. However, to prevent gas from wandering outside the pre-designed air channels, specific barrier points must be designed on the mold in gas-assisted molding processes. These barrier points become weak points in the product structure, resulting in decreased mechanical properties and potential cracking under long-term cyclic loading or accidental impact. The design of the air channels must ensure smooth gas flow and fill the predetermined area, which usually means that the air channels must be relatively simple, continuous, and have low resistance. Complex or closed annular reinforcing structures often need to be divided into multiple independent air channels, separated by multiple barrier points, which further increases the weak points in the product structure. In addition, gas-assisted molding requires materials with high melt flow rates, but high-flow materials often sacrifice toughness, which may affect the durability and lifespan of the container under low-temperature or impact conditions.

[0005] Therefore, the market urgently needs a new type of container that can fundamentally overcome the above-mentioned defects, with a seamless or near-seamless inner wall surface, higher structural integrity and material toughness, and better cleaning convenience, while maintaining or even improving its load-bearing capacity and lightweight level. Summary of the Invention

[0006] The purpose of this invention is to provide a container with structural optimization through a combination of physical micro-foaming technology.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A container comprising: Base; and Multiple side panels are fitted onto the base, and the multiple side panels define a space for accommodating items; Wherein, at least one of the side panels includes a side panel body made of plastic, the side panel body comprising: Thick-walled region, which is a local area of ​​the side plate body, wherein the wall thickness of the thick-walled region is greater than the average wall thickness of the side plate body; Thin-walled regions, which are the remaining areas of the side plate body, have a wall thickness less than that of the thick-walled regions; The average porosity of the thick-walled region is greater than that of the thin-walled region, and the thick-walled region includes a dense region on the surface and a foamed region inside, wherein the average porosity of the dense region is less than that of the foamed region.

[0008] In one embodiment, the foamed region is formed by a physical microfoaming process.

[0009] In one embodiment, the thick-walled region includes a first reinforcement portion disposed at the periphery of the side plate body.

[0010] In one embodiment, the first reinforcement is a closed-loop structure or an open-loop structure extending along the periphery of the side plate body.

[0011] In one embodiment, the thick-walled region further includes a second reinforcement portion located in the middle of the side plate body and extending along the height direction of the side plate body and connecting to the first reinforcement portion; The thin-walled region is located within the area enclosed by the first reinforcing portion and the second reinforcing portion.

[0012] In one embodiment, an air-assisted channel is further provided in the thick-walled region, and the air-assisted channel extends along the periphery of the side plate body.

[0013] In one embodiment, only one blocking part is provided in the gas-assisted channel, the blocking part blocks the gas-assisted channel, and the gas-assisted channel forms a starting section and an ending section of the channel on opposite sides of the blocking part.

[0014] In one embodiment, the starting segment and the ending segment are respectively provided with an air inlet and an air outlet communicating with the outside.

[0015] In one embodiment, the barrier portion is formed by a wall including the foamed area.

[0016] In one embodiment, the barrier portion has a hollow chamber inside.

[0017] In one embodiment, the outer surface of the side plate is a substantially smooth plane and / or curved surface.

[0018] The present invention also provides a process for preparing a container as described in any of the preceding claims, comprising the following steps: A mold is provided, wherein the mold cavity has different cavity clearances corresponding to the designed wall thicknesses of the thick-walled region and the thin-walled region; The polymer material is melted and a supercritical fluid is injected into the polymer melt to form a homogeneous polymer melt containing the supercritical fluid; The polymer melt containing supercritical fluid is injected into the mold cavity, and micropore foaming is induced by pressure drop; After cooling and solidification, the container is removed from the mold to obtain the product.

[0019] In one embodiment, during the injection step, micropores are fully grown within the thick-walled region to form a foamed region; on the surface of the thick-walled region and in the thin-walled region, foaming is inhibited to form a dense region.

[0020] The present invention also provides a process for preparing a container as described in any of the preceding claims, comprising the following steps: A mold is provided, wherein the mold cavity has different cavity clearances corresponding to the designed wall thicknesses of the thick-walled region and the thin-walled region; A first polymer material is melted, and a supercritical fluid is injected into the first polymer melt to form a homogeneous first polymer melt containing the supercritical fluid; simultaneously, a second polymer material is melted to form a second polymer melt. The second polymer material and the first polymer material are sequentially injected into the same mold, wherein the second polymer material forms a cavity in the thick-walled region, and the first polymer material pushes and fills the cavity in a molten state. After cooling and solidification, the container is removed from the mold to obtain the product.

[0021] In one embodiment, during the injection step, the second polymer material forms a dense region, and the first polymer material induces bubble nuclei within the mold due to pressure drop, and grows within the cavity corresponding to the thick-walled region, forming a foamed region within the cavity.

[0022] The present invention, employing the above-mentioned technical solution, has the following beneficial effects: The container provided by the present invention integrates physical micro-foaming technology with container structural design, pre-setting thick-walled areas with larger wall thickness and thin-walled areas with smaller wall thickness on the side plate body. The micro-foaming process forms a uniform foaming zone within the thick-walled area to achieve local reinforcement, thereby completely eliminating the grid-like grooves and cleaning dead corners caused by the reinforcing rib structure in traditional containers. This keeps the inner and outer surfaces of the container basically smooth, fundamentally solving the problems of dirt residue and cleaning difficulties, significantly reducing cleaning, drying, and maintenance costs. Furthermore, it eliminates the risk of scratches and collisions caused by reinforcing ribs to the loaded goods, effectively ensuring the quality of goods during transportation. Simultaneously, compared with existing gas-assisted molding technology, the microporous structure within the thick-walled area of ​​the present invention does not have structural weaknesses caused by gas-assisted obstruction points, resulting in superior overall mechanical properties, impact resistance, and longer service life. Moreover, it allows for the use of medium-flow materials with higher toughness, further enhancing the container's durability. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a container.

[0024] Figure 2 This is an exploded view of a container.

[0025] Figure 3 This is a partial sectional view of the long side plate of a container.

[0026] Figure 4 yes Figure 3 Enlarged view of point A in the middle.

[0027] Figure 5 yes Figure 3 A sectional view of the long side plate.

[0028] Figure 6 yes Figure 5 Enlarged view of point B in the middle.

[0029] Figure 7 This is a partial sectional view of the long side plate of another type of container.

[0030] Figure 8 yes Figure 7 A magnified view of point C in the middle.

[0031] Figure 9 yes Figure 7 Enlarged view of point D in the middle.

[0032] Figure 10 yes Figure 7 A sectional view of the long side plate.

[0033] Figure 11 yes Figure 10 Enlarged view of point E in the middle.

[0034] Figure 12 This is a partial sectional view of the long side plate of another type of container.

[0035] Figure 13 yes Figure 12 Enlarged view of point F in the middle.

[0036] Figure 14 yes Figure 12 A sectional view of the long side plate.

[0037] Figure 15 yes Figure 14 A magnified view of point G in the middle. Detailed Implementation

[0038] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to more clearly understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are only for illustrating the essential spirit of the technical solution of the present invention.

[0039] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0040] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0041] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0042] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0043] In the following description, in order to clearly demonstrate the structure and operation of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outer", "inner", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0044] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] This invention provides a container, such as Figures 1-2 As shown, the container includes a base 1 and multiple side panels 2 mounted on the base 1. In this embodiment, the side panels 2 include a pair of opposing long side panels 21 and a pair of opposing short side panels 22, with the four side panels enclosing a space for accommodating items. Preferably, the side panels can be folded relative to the base 1 to facilitate the storage and handling of the container. Specifically, the bottom of the side panels is provided with a hinge structure 23, and the edge 11 of the base 1 is provided with a hinge groove 12 that matches the hinge structure 23. The hinge structure 23 and the hinge groove 12 of the side panels cooperate to allow the side panels to be hingedly connected to the base 1. Another preferred embodiment is that an interlocking structure is provided between two adjacent side panels so that adjacent side panels can interlock and fix each other in a vertical state. Specifically, multiple first engagement structures 24 are provided on both sides of the long side plate 21 along its length, and second engagement structures 25 that match the first engagement structures 24 are provided on both sides of the short side plate 22 along its length. When the side plate is vertical relative to the base 1, the first engagement structures 24 and the second engagement structures 25 can engage and fix each other.

[0047] This embodiment uses a long side plate as an example; see [link to example]. Figures 3-6The long side panel 21 includes a side panel body 210 made of plastic, which includes at least one thick-walled region 211 and at least one thin-walled region 212. The thick-walled region is a localized area of ​​the side panel, and its wall thickness is greater than the average wall thickness of the side panel body. The thick-walled region 211 contains uniformly or substantially uniformly distributed, closed-cell or open-cell foamed areas. This thick-walled region 211 constitutes the load-bearing reinforcement area of ​​the container, used to withstand the main loads and resist deformation. Because its reinforcement effect comes from the internal microporous structure rather than external reinforcing ribs, the inner and outer surfaces of the side panel are substantially smooth planes or curved surfaces, without any grooves or protrusions formed by reinforcing ribs. The foamed areas formed inside the thick-walled region 211 can be formed using a physical micro-foaming process.

[0048] The thin-walled region 212 is the remaining area of ​​the side plate body excluding the thick-walled region 211, and its wall thickness is less than that of the thick-walled region 211. In the physical micro-foaming process, due to its thin wall thickness, the foaming ratio of this thin-walled region 212 is limited or it does not foam at all. Its main function is to define the internal space of the container and increase the effective volume of the container. Similarly, its surface is a basically smooth plane or curved surface, without any grooves or protrusions formed by reinforcing ribs.

[0049] As a first embodiment of the side plate body having the aforementioned thick-walled and thin-walled regions, see also Figures 3-6 The entire side panel body 210 is obtained using a single-material injection molding process. The specific steps are as follows: The present invention also provides a process for preparing the above-mentioned container, comprising the following steps: S11. Provide molds: Provide corresponding injection molds according to the target load-bearing and volume requirements of the container. The shape of the mold cavity corresponds to the final shape of the container, and different areas of the mold cavity have different cavity clearances, which correspond to the design wall thickness of the thick-walled area and the design wall thickness of the thin-walled area of ​​the container.

[0050] S12, Melting and Plasticizing with Gas Dissolution: The polymer material is heated and melted in an injection molding machine to form a polymer melt. Then, a supercritical fluid (preferably supercritical nitrogen or supercritical carbon dioxide) is injected into the polymer melt. Through the shearing and mixing action of the screw, the supercritical fluid is uniformly dissolved in the polymer melt to form a homogeneous polymer melt.

[0051] S13. Injection Molding: A polymer melt containing supercritical fluid is rapidly injected into a closed mold cavity. Due to the sudden drop in pressure, the supercritical fluid dissolved in the melt is in a supersaturated state, thereby inducing a large number of bubble nuclei inside the polymer.

[0052] S14. Microcellular Foaming and Cooling: The bubble nuclei continue to grow within the mold cavity, forming a foamed structure. During this process, due to the different gaps in the mold cavities, the flow and pressure distribution of the melt vary. In the thick-walled regions corresponding to larger wall thicknesses, the melt volume within the thick-walled regions is sufficient, and the pressure is well maintained, providing ample temperature and space conditions for bubble nucleation and growth, ultimately forming a thicker foamed structure. However, in the thin-walled regions corresponding to smaller wall thicknesses and on the surface of the thick-walled regions, due to the high melt flow resistance and rapid cooling rate, the space for bubble nucleation and growth is limited, resulting in a low foaming ratio in these areas, or even the formation of non-foamed dense areas. After the product has cooled and solidified, it is opened from the mold and removed, yielding the container.

[0053] The pore size distribution, pore density, and foam layer thickness of the internal microporous structure in the thick-walled region can be controlled according to the structural strength requirements. For example, in areas requiring higher strength, a greater wall thickness can be designed, resulting in a thicker foamed area after foaming, while the surface layer consists of an unfoamed or minimally foamed dense area, ensuring surface smoothness and hardness.

[0054] See also Figure 5 and Figure 6 The thick-walled region 211 includes a first reinforcing portion 2111 that surrounds the periphery of the side plate body and forms a ring, and a second reinforcing portion 2112 that is located in the middle of the side plate body, extends vertically, and connects to the first reinforcing portion 2111. The thin-walled region 212 is located within the area enclosed by the first reinforcing portion 2111 and the second reinforcing portion 2112 of the thick-walled region 211. The number of second reinforcing portions 2112 can be set according to the length of the side plate.

[0055] See Figures 7-11 Within the first reinforcing portion 2111 of the thick-walled region 211, an annular air-assisted channel 2113 is also provided, surrounding the periphery of the side plate body. The air-assisted channel 2113 contains only one air-assisted blocking portion 2114, which blocks the air-assisted channel 2113 and forms a starting portion 2115 and an ending portion 2116 on opposite sides of the blocking portion 2114. The starting portion 2115 and the ending portion 2116 are respectively provided with an air inlet 2117 and an air outlet 2118 connecting the air-assisted channel 2113 to the outside. In this embodiment, the air-assisted blocking portion 2114 is composed of a wall including a foaming area, and the interior of the air-assisted blocking portion 2114 has a cavity 21141 enclosed by the wall, which enhances the strength of the location of the air-assisted blocking portion 2114. In this embodiment, the thick-walled area has higher strength due to the foaming zone. Therefore, the gas-assisted channel 2113 can be designed to have only one gas-assisted barrier 2114. The gas-assisted channel structure is simple, and the mechanical properties at the location of the gas-assisted barrier 2114 will not or will not decrease, and will not become a weak point in the product structure.

[0056] As a second embodiment of the side plate body having thick-walled and thin-walled regions described above, see also... Figures 12-15 The entire side panel body 210 is manufactured using a co-injection molding process. The specific steps are as follows: S21. Provide molds: Provide corresponding injection molds according to the target load-bearing and volume requirements of the container. The shape of the mold cavity corresponds to the final shape of the container, and different areas of the mold cavity have different cavity clearances, which correspond to the design wall thickness of the thick-walled area and the design wall thickness of the thin-walled area of ​​the container.

[0057] S22. Melting, Plasticizing, and Gas Dissolution: The first polymer material is heated and melted in an injection molding machine to form a first polymer melt. Then, a supercritical fluid (preferably supercritical nitrogen or supercritical carbon dioxide) is injected into the first polymer melt. Through the shearing and mixing action of the screw, the supercritical fluid is uniformly dissolved in the first polymer melt to form a homogeneous single-phase solution. Simultaneously, the second polymer material is heated and melted in a separate injection molding machine to form a second polymer melt. The first and second polymer materials can be the same or different.

[0058] S23. Injection Molding: Using two or more injection systems, a second polymer material and a first polymer material are sequentially injected into the same mold. The second polymer material forms a cavity in the thick-walled region, and the first polymer material pushes and fills the cavity while its cavity material is in a molten state. Due to the sudden pressure drop within the mold, the supercritical fluid dissolved in the first polymer melt is in a supersaturated state, thereby inducing a large number of bubble nuclei inside the first polymer.

[0059] S24. Microporous Foaming and Cooling: The second polymer material forms a surface structure throughout the mold cavity, constituting the outer layer structure 2101 of the side plate body 210. It forms cavities in the thick-walled regions and solid structures without cavities in the thin-walled regions. The first polymer material is injected into the cavity formed by the second polymer material in the thick-walled region. The bubble nuclei inside the first polymer material continue to grow within the cavity, forming a foamed structure, which constitutes the inner layer 2102 of the side plate body 210. After the product cools and sets, it is opened from the mold to obtain the container.

[0060] The preferred embodiments of the present invention have been described in detail above. However, it should be understood that after reading the above teachings, those skilled in the art can make various alterations or modifications to the present invention. These equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A container, characterized in that, include: Base; as well as Multiple side panels are fitted onto the base, and the multiple side panels define a space for accommodating items; Wherein, at least one of the side panels includes a side panel body made of plastic, the side panel body comprising: Thick-walled region, which is a local area of ​​the side plate body, wherein the wall thickness of the thick-walled region is greater than the average wall thickness of the side plate body; Thin-walled regions, which are the remaining areas of the side plate body, have a wall thickness less than that of the thick-walled regions; The average porosity of the thick-walled region is greater than that of the thin-walled region, and the thick-walled region includes a dense region on the surface and a foamed region inside, wherein the average porosity of the dense region is less than that of the foamed region.

2. The container according to claim 1, characterized in that, The foaming zone is formed by a physical micro-foaming process.

3. The container according to claim 1, characterized in that, The thick-walled region includes a first reinforcing portion, which is disposed at the periphery of the side plate body.

4. The container according to claim 3, characterized in that, The first reinforcement is a closed-loop structure or an open-loop structure that extends along the periphery of the side plate body.

5. The container according to claim 3, characterized in that, The thick-walled region further includes a second reinforcement portion, which is located in the middle of the side plate body and extends along the height direction of the side plate body and connects to the first reinforcement portion; The thin-walled region is located within the area enclosed by the first reinforcing portion and the second reinforcing portion.

6. The container according to claim 1, characterized in that, An air-assisted channel is also provided in the thick-walled area, and the air-assisted channel extends along the periphery of the side plate body.

7. The container according to claim 6, characterized in that, The gas-assisted channel is provided with only one blocking part, which blocks the gas-assisted channel and makes the gas-assisted channel form the starting section and the ending section of the channel on opposite sides of the blocking part.

8. The container according to claim 7, characterized in that, The starting section and the ending section are respectively provided with an air inlet and an air outlet that communicate with the outside.

9. The container according to claim 7, characterized in that, The barrier portion is formed by a wall including the foamed area.

10. The container according to claim 9, characterized in that, The barrier section has a hollow chamber inside.

11. The container according to claim 1, characterized in that, The outer surface of the side plate is a generally smooth plane and / or curved surface.

12. A process for preparing a container as described in any one of claims 1 to 11, characterized in that, Includes the following steps: A mold is provided, wherein the mold cavity has different cavity clearances corresponding to the designed wall thicknesses of the thick-walled region and the thin-walled region; The polymer material is melted and a supercritical fluid is injected into the polymer melt to form a homogeneous polymer melt containing the supercritical fluid; The polymer melt containing supercritical fluid is injected into the mold cavity, and micropore foaming is induced by pressure drop; After cooling and solidification, the container is removed from the mold to obtain the product.

13. The process according to claim 12, characterized in that, During the injection step, micropores grow sufficiently within the thick-walled region to form a foamed area; on the surface of the thick-walled region and in the thin-walled region, foaming is inhibited to form a dense area.

14. A process for preparing a container as described in any one of claims 1 to 11, characterized in that, Includes the following steps: A mold is provided, wherein the mold cavity has different cavity clearances corresponding to the designed wall thicknesses of the thick-walled region and the thin-walled region; A first polymer material is melted, and a supercritical fluid is injected into the first polymer melt to form a homogeneous first polymer melt containing the supercritical fluid; simultaneously, a second polymer material is melted to form a second polymer melt. The second polymer material and the first polymer material are sequentially injected into the same mold, wherein the second polymer material forms a cavity in the thick-walled region, and the first polymer material pushes and fills the cavity in a molten state. After cooling and solidification, the container is removed from the mold to obtain the product.

15. The process according to claim 14, characterized in that, During the injection step, the second polymer material forms a dense region, and the first polymer material induces bubble nuclei in the mold due to pressure drop, which grow in the cavity corresponding to the thick-walled region, forming a foaming region in the cavity.

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