Manufacturing method for container products
The method simplifies the manufacturing of plastic cups by controlling pressure and mold movement to form a container with varying foam thickness, improving heat insulation and appearance without complex temperature control.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- CHENG LUN ENTERPRISE CO LTD
- Filing Date
- 2023-05-23
- Publication Date
- 2026-05-25
AI Technical Summary
Existing methods for manufacturing thick plastic cups with foamed structures for improved heat insulation complicate the manufacturing process and are difficult to control, affecting the appearance and texture.
A manufacturing method involving a mold with specific regions and controlled pressure and movement to form a container with a micro-foamed region and a foamed region, allowing for controlled thickness and shape without complex temperature control.
The method simplifies the manufacturing process, ensures product uniformity and quality, and enhances appearance and heat insulation by forming a container with a conical annular wall and varying foam thickness.
Smart Images
Figure 2026516517000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for manufacturing a container product, and more particularly to a method for manufacturing a cup-shaped container product that is melt-molded using a polymer and a foaming agent.
Background Art
[0002] Currently, injection-molded plastic cups are widely used as disposable cups. From the perspective of cost reduction, these plastic cups are manufactured with the minimum thickness capable of storing beverages. However, such thin plastic cups are inferior in heat insulation, and when hot beverages are poured, heat is transmitted to the outside, causing discomfort to the hand.
[0003] To improve the drawback of the inferior heat insulation of the plastic cup, currently, in the manufacture of plastic cups, a method of molding a molten resin composition composed of a polymer and a foaming agent is used. It becomes possible to form a thick plastic cup having a foamed structure after molding, and a better heat insulation effect can be provided compared to non-foamed plastic cups.
[0004] However, when the entire plastic cup has a thick foamed structure, there is a drawback that the appearance changes and the texture becomes poor. For example, the plastic cup disclosed in Patent Document 1 forms a cup having a foamed portion and a non-foamed portion by suppressing foaming at the cooling site and causing foaming at the non-cooling site by a temperature control method of cooling a part of the mold. However, such a method that requires local cooling control has drawbacks of complicating the manufacturing process and making control difficult.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Summary of the Invention
[0006] The present invention aims to provide a method for manufacturing container products that reduces the complexity of the manufacturing process while also providing the product with excellent heat insulation, appearance, and texture. [Means for solving the problem]
[0007] The manufacturing method for the container product includes the following steps:
[0008] S1: This is the step of installing a mold comprising a first member having a first surface and a second member having a second surface and an air inlet.
[0009] S2: This step involves clamping the mold to define a cavity between the first surface and the second surface. The cavity has a conical annular space, which has a first end corresponding to the axial direction and a second end corresponding to the axial direction with a smaller diameter than the first end, and a bottom space perpendicular to the axial direction is formed at the second end. The cavity has a first region and a second region, the distance between the first surface and the second surface in the first region is shorter than the distance between the first surface and the second surface in the second region, and both ends of the second region in the axial direction are connected to the first region.
[0010] S3: This step involves injecting a molten resin composition containing a polymer and a physical blowing agent into the cavity under injection pressure.
[0011] S4: This step involves cooling the molten resin composition in the cavity to completely cool and cure the first region, or to leave a small amount of uncooled molten resin composition in the center. The second region has a first solid surface layer and a second solid surface layer in contact with the first and second surfaces, respectively, with the molten resin composition held between the first and second solid surface layers. The molten resin composition in the cavity is subjected to a pressure higher than the gas pressure required to maintain the physical foaming agent dissolved in the polymer, thereby preventing the molten resin composition in the first and second regions from foaming.
[0012] S5: This step involves blowing air from an air inlet to adhere the resin composition to the first surface of the first member, and then stopping the air blowing after adhesion. As a result, the first member of the mold is moved axially, and the molten resin composition in the cavity is exposed to a pressure lower than the gas pressure required to maintain the state in which the physical foaming agent is dissolved in the polymer, thereby increasing the distance between the first and second surfaces at the position corresponding to the second region of the mold. At this time, the first solid surface layer remains in contact with the first surface, the molten resin composition in the center of the second region foams and expands to form a honeycomb-like foam, and the second solid surface layer becomes able to contact the second surface. Furthermore, the resin composition in the first region remains in contact with the first surface, the first region has already hardened, or only slight foaming occurs, the shape and thickness of the first region do not change fundamentally, or only slightly increase in thickness, and the first region restricts the expansion direction of the second region to only the first surface side.
[0013] S6: This is a cooling step in which the foamed container product is cooled and shaped in the mold.
[0014] S7: This is a mold opening step in which the first and second components of the mold are separated and the container product is removed.
[0015] In one embodiment of the present invention, the first region is a position corresponding to the bottom space and a part of the annular space extending from the first end to the second end, and the second region is a position within the annular space extending from the first region to the bottom space. [Effects of the Invention]
[0016] The manufacturing method of the present invention does not require complex temperature control and allows for control of the container thickness according to the movement distance of the first component of the mold, thereby achieving excellent manufacturing quality, yield, and product uniformity. The container manufactured by the present invention has an annular wall, with a bottom wall below the annular wall and an opening above it, and the annular wall exhibits a substantially conical surface that gradually narrows in diameter from the opening above to the bottom wall below. Furthermore, the top and bottom of the annular wall are micro-foamed regions corresponding to the first region of the mold, and a foamed region corresponding to the second region of the mold is formed between the micro-foamed region corresponding to the top of the annular wall and the bottom wall. The thickness of the foamed region is greater than the thickness of the micro-foamed region, improving the appearance and texture of the container product, and the thick foamed region provides excellent heat insulation.
[0017] The present invention can be more clearly understood by providing a detailed description of exemplary embodiments of the present invention with reference to the drawings. [Brief explanation of the drawing]
[0018] [Figure 1] This is a schematic cross-sectional view showing the mold clamping state and injection of the molten resin composition of the present invention. [Figure 2] This is a schematic cross-sectional view showing the axial movement of the first member of the mold of the present invention. [Figure 3] This is a schematic diagram showing the first region (micro-foamed area) and the second region (foamed area) in the present invention. [Figure 4] This is a schematic diagram of the container product according to the present invention. [Modes for carrying out the invention]
[0019] Referring to Figures 1 to 3, the method for manufacturing a container product according to the present invention includes the following steps.
[0020] S1: Install the mold 1 including the first member 11 having the first surface 111 and the second member 12 having the second surface 121 and the air inlet 122. A ventilation block 123 is provided at a position corresponding to the second surface 121 of the air inlet 122.
[0021] S2: Close the mold 1 to define a cavity 13 between the first surface 111 and the second surface 121. The cavity 13 has a substantially conical annular space portion 14. FIGS. 1 and 2 show only a partial cross-section of the mold 1. The annular space portion 14 has a first end 141 corresponding to the axial direction and a second end 142 corresponding to the axial direction with a smaller diameter than the first end 141. A bottom space portion 15 perpendicular to the axial direction is formed at the second end 142, and the air blowing direction of the air inlet 122 corresponds to the bottom space portion 15. The cavity 13 has a first region 16 and a second region 17. Both ends of the second region 17 corresponding to the axial direction are connected to the first region 16. In this embodiment, the first region 16 is formed by the bottom space portion 15 and a part of the annular space portion 14 from the first end 141 to the second end 142. The second region 17 is formed between the first region 16 and the bottom space portion 15 in the annular space portion 14. The distance D1 between the first surface 111 and the second surface 121 in the first region 16 is shorter than the distance D2 between the first surface 111 and the second surface 121 in the second region 17. In this embodiment, D1 may be about 0.5 mm and D2 may be about 1 mm.
[0022] S3: Inject the molten resin composition 2 containing the polymer and the physical foaming agent into the cavity 13 under an injection pressure. The physical foaming agent is a gas 21 dissolved in the polymer. The polymer may be polypropylene, and the foaming agent may be nitrogen. The ventilation block 123 can prevent the molten resin composition 2 from flowing into the air inlet 122.
[0023] S4: A step to cool the molten resin composition 2 in the cavity 13 of the mold 1 to completely cool and harden the first region 16, or to leave a small amount of uncooled molten resin composition 2 in the center. The second region 17 has a first solid surface layer 22 and a second solid surface layer 23, shown in Figures 2 and 3, in contact with the first surface 111 and the second surface 121, respectively, and holds the molten resin composition 2 between the first solid surface layer 22 and the second solid surface layer 23.
[0024] The molten resin composition 2 in the cavity 13 is subjected to a pressure higher than the pressure of the gas 21 required to maintain the state in which the physical foaming agent is dissolved in the polymer, thereby preventing the molten resin composition 2 in the first region 16 and the second region 17 from foaming.
[0025] Furthermore, step S4 is a step in which the first region 16 and the second region 17 are cooled at the same cooling temperature. Because the thickness D1 of the first region 16 is small, the first region 16 is cured by this cooling temperature, or cured almost completely to the extent that a small amount of uncooled molten resin composition 2 remains in the center.
[0026] S5: This step involves blowing air from the air inlet 122 to adhere the resin composition 2 to the first surface 111 of the first member 11, and then stopping the air blowing after adhesion. As a result, the first member 11 of the mold 1 is moved axially, and the molten resin composition 2 in the cavity 13 is exposed to a pressure lower than the pressure of the gas 21 required to maintain the state in which the physical foaming agent is dissolved in the polymer, thereby increasing the distance between the first surface 111 and the second surface at the position corresponding to the second region 17 of the mold 1. At this time, the first solid surface layer 22 is held in contact with the first surface 111, the molten resin composition 2 in the center of the second region 17 foams and expands to form a honeycomb-shaped foam 24, the second solid surface layer 23 becomes able to contact the second surface 121, and the shape and thickness of the second region 17 are limited by the distance the first member 11 moves. In this embodiment, the thickness D3 of the resin composition 2 in the second region 17 after foaming is about 2.3 mm.
[0027] Since the first region 16 is already hardened or has a small amount of molten resin composition 2 in its center, only slight foaming occurs, and the molten resin composition 2 in the first region 16 remains in contact with the first surface 111 but cannot expand to come into contact with the second surface 121. Therefore, the shape and thickness of the first region 16 do not change fundamentally, or only increase slightly in thickness. Furthermore, since the first region 16 is almost fully formed before the movement of the first member 11, the molten resin composition 2 in the second region 17 is limited to foaming and expanding only in the direction of the second surface 121 and does not expand in the axial direction of the mold 1. This improves the shape stability of the container product.
[0028] S6: A cooling step in which the foamed container product is cooled and shaped in the mold 1, wherein the cooling is performed by cooling the first region 16 and the second region 17 at the same cooling temperature, or by natural cooling in a room temperature environment.
[0029] S7: This is a mold opening step in which the first member 11 and the second member 12 of the mold are separated and the container product is removed.
[0030] Please refer to Figures 1 to 4. The container 3 manufactured by the manufacturing method according to the present invention has an annular wall 31, with a bottom wall 32 below the annular wall 31 and an opening 33 above it, and the annular wall 31 has a substantially conical surface that gradually decreases in diameter from the upper opening 33 to the lower bottom wall 32. In addition, a part of the top of the annular wall 31 and the bottom wall 32 are a micro-foamed region 34 corresponding to the first region 16 of the mold 1. Between the micro-foamed region 34 corresponding to the top of the annular wall 31 and the bottom wall 32, a foamed region 35 corresponding to the second region 17 of the mold 1 is formed, and the thickness of the foamed region 35 is greater than the thickness of the micro-foamed region 34, improving the appearance and texture of the container 3 product and providing excellent heat insulation due to the thick foamed region 35.
[0031] In this invention, the foaming thickness of the foamed area of the container can be controlled by the movement distance of the first component of the mold, making it possible to easily adjust the shape and thickness of the container. Furthermore, since this invention does not require individual temperature control for different areas, the complexity of the manufacturing process can be reduced, and it is possible to maintain better product quality, yield, and uniformity. In addition, by forming foamed areas and micro-foamed areas at different locations on the container, it is possible to impart a superior texture to the product.
[0032] The embodiments described above are merely examples of the present invention and do not limit it. Various equivalent modifications based on the spirit of the present invention are also included within the technical scope of the present invention. [Explanation of symbols]
[0033] 1. Mold 11. First Member 111 1st surface 12 Second Member 121 Second surface 122 Air intake 123 Ventilation block 13 Cavity 14. Circular space 141 1st end 142 2nd end 15 Bottom space 16 First area 17 Second area 2 Resin composition 21 Gases 22 1st solid epidermal layer 23 Second solid epidermal layer 24 Foam 3 containers 31 Ring Wall 32 Bottom wall 33 Opening 34. Slightly effervescent area 35 Foaming Area
Claims
1. S1: A step of installing a mold comprising a first member having a first surface and a second member having a second surface and an air inlet, S2: A step of clamping the mold to define a cavity between the first surface and the second surface, wherein the cavity has a conical annular space, the annular space has a first end corresponding to the axial direction and a second end corresponding to the axial direction having a smaller diameter than the first end, a bottom space perpendicular to the axial direction is formed at the second end, the cavity has a first region and a second region, the distance between the first surface and the second surface in the first region is shorter than the distance between the first surface and the second surface in the second region, and both ends of the second region in the axial direction are connected to the first region, S3: A step of injecting a molten resin composition containing a polymer and a physical blowing agent into the cavity under injection pressure, S4: A step of cooling the molten resin composition in the cavity to completely cool and harden the first region, or to leave a small amount of the molten resin composition uncooled in the central part, wherein the second region has a first solid surface layer and a second solid surface layer in contact with the first and second surfaces, respectively, a molten resin composition is held between the first and second solid surface layers, and the molten resin composition in the cavity is exposed to a pressure higher than the gas pressure required to maintain the state in which the physical foaming agent is dissolved in the polymer, thereby preventing the molten resin composition in the first and second regions from foaming. S5: A step of blowing air from the air inlet to adhere the resin composition to the first surface of the first member, and stopping the air blowing after adhesion, wherein the first member of the mold is moved axially, and the molten resin composition in the cavity is exposed to a pressure lower than the gas pressure required to maintain the state in which the physical foaming agent is dissolved in the polymer, thereby increasing the distance between the first surface and the second surface at a position corresponding to the second region of the mold, at which time the first solid surface layer is kept in contact with the first surface, the molten resin composition in the center of the second region foams and expands to form a honeycomb foam, the second solid surface layer becomes able to contact the second surface, and the resin composition in the first region is in contact with the first surface, the first region has already hardened, or only slight foaming occurs, the shape and thickness of the first region do not change basically, or only the thickness increases slightly, and the first region restricts the expansion direction of the second region to only the first surface side, S6: A cooling step in which the foamed container product is cooled and shaped in the mold, S7: A mold opening step in which the first and second members of the mold are separated and the container product is removed, A method for manufacturing a container product, characterized by including the following:
2. The method for manufacturing a container product according to claim 1, characterized in that the first region is a position corresponding to the bottom space and a part of the annular space extending from the first end to the second end, and the second region is a position within the annular space extending from the first region to the bottom space.
3. The method for manufacturing a container product according to claim 1, characterized in that the direction of air blowing from the air blowing port corresponds to the bottom space.
4. A method for manufacturing a container product according to claim 1, characterized in that a ventilation block is provided at a position corresponding to the second surface of the air inlet.
5. The method for manufacturing a container product according to claim 1, characterized in that the polymer is polypropylene.
6. The method for producing a container product according to claim 1, characterized in that the physical foaming agent is nitrogen.
7. The method for manufacturing a container product according to claim 1, characterized in that the step S4 is a step of cooling the first region and the second region at the same cooling temperature.
8. The method for manufacturing a container product according to claim 1, characterized in that the cooling step S6 is a step of cooling the first region and the second region at the same cooling temperature, or a step of natural cooling in a room temperature environment.