Two-color injection-molded integrated cover with circular-arch reinforcing structure

Abstract

The application discloses a double-color injection-molded integrated cover with a circular-arch reinforcing structure, comprising an outer cover and a sealing element, wherein the sealing element is a non-rigid element, and the sealing element is integrally formed with the outer cover through a double-color injection molding process; one end of the sealing element towards the inside of the outer cover is provided with a curved surface structure, which is configured to store energy by structural deformation when a puncture needle is punctured; and the other end of the sealing element towards the outside of the outer cover is provided with a puncture surface, so that the needle tip enters the sealing element from the puncture surface and leaves the sealing element from the curved surface structure when the puncture needle is punctured. After the needle is pulled out, the sealing element can realize the rapid closure of the puncture hole by releasing the energy stored by structural deformation, thereby reducing the risk of liquid leakage when the needle is pulled out and preventing the risk of injury to medical staff caused by medicines. Moreover, the application only needs to modify the curved surface structure of the injection mold cavity, without the need to replace production equipment or adjust injection molding process parameters, and the original automatic assembly line can be directly adapted.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically, to a two-color injection-molded one-piece cap with a domed reinforcement structure. Background Technology

[0002] With the continuous upgrading of national environmental protection standards and safe use guidelines for medical consumables in the pharmaceutical industry, the drawbacks of traditional vulcanized rubber infusion caps and pads are becoming increasingly apparent. The production process of traditional vulcanized rubber pads presents environmental problems such as vulcanization waste gas pollution, high energy consumption, and the inability to recycle and reuse scrap materials. Furthermore, the high hardness of the rubber pad material results in significant puncture resistance, easily causing needle bending and making puncture difficult for medical personnel. Moreover, waste rubber consumables are difficult to degrade, failing to meet the requirements for green and low-carbon development in medical packaging.

[0003] To address the issues of shavings and environmental concerns associated with traditional rubber composite caps, companies in related industries have been exploring the use of thermoplastic elastomers (TPEs) to replace rubber gaskets in integrated composite caps for over a decade. These caps are safer, more environmentally friendly, and have lower energy consumption. Domestic companies such as Hebei Xiangyi Pharmaceutical Technology Co., Ltd. (patent name: A Thermoplastic Elastomer Plastic Composite Cap for Pharmaceuticals, patent number: CN215555668 U) and Chongzhou Junjian Plastics Co., Ltd. (patent name: An Integrated Composite Cap, patent number: CN219440003 U) have developed integrated composite caps that use TPEs instead of rubber gaskets. These caps are manufactured using a two-color injection molding process, simplifying the production process and avoiding the risks of rubber vulcanization pollution and shavings. However, these products have a core defect in terms of sealing performance: due to an unreasonable overall structural design, the thickness, hardness, and sealing surface dimensions of the internal TPE plug are poorly matched, resulting in poor rebound sealing after clinical needle puncture. This leads to leakage and seepage through the puncture site, failing to meet the core requirements for infusion sealing. This defect resulted in the product completing its technological development but failing to pass clinical trials, thus preventing its large-scale market application.

[0004] The dual-color TPE combination cap invented by Shanghai Pacific Industrial Co., Ltd. (patent name: dual-color combination cap for infusion plastic bottles and dual-color combination cap for infusion containers, patent number: CN 209347642 U) optimizes the structural dimensions of the cap body and the internal TPE stopper based on the ordinary one-piece TPE combination cap. It retains the advantages of dual-color injection molding and good environmental protection. However, the two ends of its sealing structure are designed vertically, and the sealing recovery force relies entirely on the elasticity of the TPE material itself. Due to the inherent limited resilience of TPE material, after stress relaxation under prolonged puncture stress, the remaining rebound force is insufficient to drive the puncture hole to close fully. In clinical use, there are still problems such as loose rebound and poor sealing recovery ability after puncture; after needle removal, the puncture hole cannot be completely closed, resulting in leakage and posing a safety risk of drug splashing and contamination of medical staff.

[0005] Furthermore, the vertical end face structure of this product makes it difficult for gas to escape from the mold cavity during secondary injection molding of TPE material, resulting in incomplete filling of TPE melt, easy generation of a large number of air bubbles, strong concealment of defects, and difficulty in completely screening out by conventional testing. The product qualification rate is low, and the high defect rate drives up the unit product cost, making it difficult to meet the large-scale low-cost demand of the domestic infusion market, and the market has not been effectively promoted.

[0006] In summary, the fundamental flaw in current infusion cap products using thermoplastic elastomers as seals lies in their reliance on the elasticity of the sealing material itself for seal recovery. The inherent resilience of non-rigid materials like TPE is insufficient to maintain an effective seal for an extended period after puncture. This leads to the puncture site failing to close quickly after needle removal, resulting in leakage risks that endanger healthcare workers, waste medication, and cause cross-contamination. Therefore, there is an urgent need for a sealing solution that can compensate for the insufficient resilience of non-rigid materials through structural improvements without altering the choice of sealing material, fundamentally solving the technical challenges of insufficient rebound after puncture and leakage upon needle removal. Summary of the Invention

[0007] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0008] To at least partially solve the above problems, the present invention provides a two-color injection molded integral cap with a domed reinforcing structure, comprising: an outer cap and a sealing element, wherein the sealing element is a non-rigid component, and the sealing element is integrally formed with the outer cap by a two-color injection molding process; the end of the sealing element facing the inside of the outer cap has a curved surface structure, the curved surface structure being configured to store energy by generating structural deformation when punctured by a puncture needle, and the end of the sealing element facing the outside of the outer cap has a puncture surface, wherein when punctured by a puncture needle, the needle tip enters the sealing element through the puncture surface and exits the sealing element through the curved surface structure.

[0009] Preferably, the curved surface structure is an arched protrusion, and the two ends of the arched protrusion are connected to the sidewall of the seal by a rounded transition.

[0010] Preferably, the curved surface structure is a spherical protrusion, and the edge of the spherical protrusion is connected to the edge of the puncture surface.

[0011] Preferably, the puncture surface is planar.

[0012] Preferably, the puncture surface is a concave surface that is recessed into the outer cover.

[0013] Preferably, the maximum effective chord length D of the seal located inside the outer cover is 36 mm.

[0014] Preferably, the minimum effective chord length d of the seal located inside the outer cover is 4 mm.

[0015] Preferably, the puncture surface is circular or polygonal.

[0016] Preferably, it also includes a liquid-blocking membrane located inside the outer cover and covering the curved structure of the seal.

[0017] Preferably, the liquid-sealing membrane and the outer cover are made of the same material, and the outer cover, the liquid-sealing membrane and the sealing element are integrally formed by a two-color injection molding process.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] After needle removal, the sealing element releases the energy stored in its structural deformation to quickly close the puncture hole, thereby reducing the risk of leakage and preventing harm to medical personnel from medication. Furthermore, this application only requires modification of the curved surface structure of the injection mold cavity; it does not require changing production equipment or adjusting injection process parameters. Existing automated assembly lines can be directly adapted, maintaining the same production efficiency as traditional flat gaskets. The production cost increase per unit is less than 2%. This application is suitable for large-scale industry-wide replacement, perfectly meeting the dual urgent needs of environmentally friendly upgrades and safe clinical use of pharmaceutical materials.

[0020] The two-color injection-molded one-piece cap with a domed reinforcement structure described in this invention will have other advantages, objectives and features that will be partly apparent from the following description, and partly understood by those skilled in the art through study and practice of the invention. Attached Figure Description

[0021] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is a cross-sectional structural diagram of the seal when the effective chord length is D (the puncture surface is a plane).

[0023] Figure 2 This is a schematic diagram of the cross-sectional structure of the seal when the effective chord length is d (the puncture surface is concave).

[0024] Figure 3 This is a schematic diagram of the cross-sectional structure when the puncture surface is concave.

[0025] Figure 4A cross-sectional structural diagram of the liquid diaphragm (the puncture surface is flat, and the liquid diaphragm only covers the curved structure).

[0026] Figure 5 A cross-sectional structural diagram of the liquid diaphragm (the puncture surface is concave, and the liquid diaphragm only covers the curved structure).

[0027] Figure 6 The diagram shows a circular puncture surface with the liquid-sealing membrane covering both the inner end face of the outer cap and the curved surface structure. (A) is a sectional view of the front view, and (B) is a top view.

[0028] Figure 7 The diagram shows a case where the puncture surface and the outer end face of the outer cover are not on the same plane and the liquid-blocking membrane simultaneously covers the inner end face of the outer cover and the curved surface structure. (A) is a sectional view of the front view, (B) is a top view, and (C) is a sectional view of the left view.

[0029] Figure 8 In the middle (A)-(H), the top views are respectively when the puncture surface is a circle and a polygon.

[0030] In the diagram: 1. Outer cover, 2. Seal, 3. Curved structure, 4. Puncture surface, 5. Liquid diaphragm. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, so that those skilled in the art can implement it based on the description.

[0032] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0033] like Figures 1-8As shown, this invention provides a two-color injection-molded integrated cap with a domed reinforcing structure, comprising: an outer cap 1 and a sealing element 2, wherein the sealing element 2 is a non-rigid component. Preferably, the sealing element 2 is made of thermoplastic elastomer (TPE), and the sealing element 2 is integrally molded with the outer cap 1 through a two-color injection molding process; the end of the sealing element 2 facing the inside of the outer cap 1 has a curved surface structure 3, which extends into the inside of the outer cap 1. The curved surface structure 3 is configured to store energy through structural deformation when a puncture needle is inserted. That is, from the moment the puncture needle reaches the curved surface structure 3, as the puncture needle moves, the curved surface structure 3 is compressed and undergoes elastic deformation, thereby storing energy and keeping the sealing element 2 in close contact with the outer wall of the puncture needle. When the puncture needle is withdrawn, the compressed elastic potential energy is released, thereby quickly sealing the puncture hole. This invention compensates for the material defects of TPE through pure physical structural optimization, while retaining the original advantages of TPE gaskets such as environmental friendliness, easy puncture, and low cost. The sealing element 2 has a puncture surface 4 at one end facing the outside of the outer cover 1. When the puncture needle punctures, the needle tip enters the sealing element 2 through the puncture surface 4 and leaves the sealing element 2 through the curved surface structure 3.

[0034] By incorporating a curved structure 3 on the seal 2, the deformation compensation mechanism of the physical structure can be fully utilized, upgrading the sealing recovery force from simply "relying on material elasticity" to "relying on the combined effect of structural geometry and material elasticity." When the puncture needle is inserted, the curved structure 3 stores energy through structural deformation. During infusion, the seal 2 tightly wraps around the puncture needle body through deformation, maintaining a sealed state. When the puncture needle is withdrawn, the curved structure 3 releases the stored energy, driving the seal 2 to return to its original shape and close the puncture orifice, fundamentally compensating for the inherent deficiency of the material's own resilience. After needle removal, the seal 2 achieves rapid closure of the puncture orifice by releasing the energy stored in its structural deformation, thereby reducing the risk of leakage during needle removal and preventing injury to medical personnel from medication. Furthermore, this application only requires modification of the curved surface structure of the injection mold cavity, without the need to replace production equipment or adjust injection process parameters. Existing automated assembly lines can be directly adapted, and the production efficiency remains consistent with that of traditional flat gaskets. The production cost increase per product is less than 2%. This application is suitable for large-scale industry-wide replacement and perfectly meets the dual urgent needs of environmental upgrading and clinical safety of current pharmaceutical materials.

[0035] In existing technologies, ordinary TPE combination caps exhibit poor rebound sealing after clinical needle puncture, easily leading to leakage and seepage at the puncture site. This leakage typically lasts 2-4 hours because the stress state around the puncture site in existing technologies is tensile stress. Under tension, the material's resilience is weak, making it difficult for the puncture site to close. The thermoplastic elastomer section in patent CN209347642 U features a vertical design at both ends. This vertical structure makes it difficult for gas to escape from the mold cavity during secondary injection molding of TPE material, resulting in incomplete TPE melt filling and the generation of numerous air bubbles. Furthermore, the defects are highly concealed, making them difficult to completely eliminate using conventional testing, leading to a low product qualification rate. A high defect rate naturally increases the unit cost of the product, resulting in insufficient cost-effectiveness and failing to meet the large-scale, low-cost demand of the domestic infusion market, thus hindering its effective market promotion. CN209347642U relies on "downward squeezing under the pressure of the remaining liquid in the container" to close the needle hole upon needle removal. This mechanism is limited by the magnitude of the remaining liquid pressure in the container, and the closure effect may be unstable.

[0036] As one of many implementation methods, the curved structure 3 is an arched protrusion, and the two ends of the arched protrusion are connected to the side wall of the sealing element 2 by a rounded transition. The arched protrusion can be a long, narrow arch, in which case the area of ​​the puncture surface is not limited, and the size of the curved structure 3 is not limited, so it can be adapted to the design requirements of infusion caps of different specifications.

[0037] The arched protrusion structure utilizes the principles of arch mechanics to transform the stress state around the puncture site from tension to compression, upgrading the seal recovery force from "relying on material elasticity" to "relying on structural geometry and material elasticity." The arched protrusion structure leverages the hyperelastic properties of thermoplastic elastomers (TPEs) and its bottom arched design, giving it an "arch effect" and significant circumferential tension. When the infusion is finished and the needle is removed, the arched structure, due to its overall rebound tendency, causes the two sides of the incision to compress and close towards the center. This geometric "closing" tendency is very strong, completely sealing the puncture site at the moment of needle removal, thus preventing leakage during needle removal, reducing the risk of injury to medical staff from medication, and minimizing medication waste and cross-contamination.

[0038] The arched protrusion utilizes a structural deformation energy storage mechanism to compensate for the resilience shortcomings of TPE material, making it less prone to leakage and seepage due to punctures. The seal can be maintained for 4-8 hours, far exceeding the conventional requirements for fluid delivery sealing. In addition, the arched surface has no sharp corners or blind cavities. Utilizing the "wall effect" of fluid mechanics, the TPE melt can flow smoothly along the curved surface during injection molding. During the flow, there are no eddies or trapped gases. Gases are uniformly squeezed to the parting surface by the melt and smoothly discharged through the mold parting surface. This achieves a tight fit between TPE and the outer cover 1, thus avoiding defects such as bubbles and delamination at the joint surface.

[0039] As one of many implementation methods, the curved surface structure 3 is a spherical protrusion, and the edge of the spherical protrusion is connected to the edge of the puncture surface 4, such as... Figure 1 , Figure 2 As shown, the spherical protrusion possesses structural deformation energy storage capacity in all directions within three-dimensional space. Uniform deformation energy storage compensation and rebound sealing force are achieved regardless of the direction the puncture needle is inserted. The spherical surface has no sharp corners or blind cavities, allowing the TPE melt to flow smoothly along the spherical surface, achieving a close fit with the outer cover 1 and thus avoiding defects such as bubbles and delamination at the bonding surface. The overall rebound tendency of the spherical protrusion drives the puncture hole to contract and close towards the center in all directions during needle withdrawal, completely sealing the needle hole at the moment of needle removal and preventing leakage during needle withdrawal. This reduces the risk of injury to medical personnel from medication and minimizes the risk of medication waste and cross-contamination.

[0040] As one of many implementation methods, the puncture surface 4 is a plane. The plane puncture surface can fit smoothly with the outer end face of the infusion cap, so that the force is even when the puncture needle is inserted, and it is not easy to deviate. This can effectively reduce the difficulty of puncture operation and the risk of needle bending, and reduce the effort required for medical staff to perform puncture.

[0041] As mentioned above, the sealing time of the arched protrusion in this application can be as long as 4 to 8 hours. However, under certain extreme conditions (such as infusion time exceeding 8 hours, large fluctuations in infusion pressure, etc.), a structural design with a more significant sealing effect is required. As one of the many embodiments, the puncture surface 4 is a concave surface that is recessed into the outer cover 1.

[0042] Preferably, the thickness of the puncture surface 4 is between 0.2mm and 2mm. This ensures sufficient structural deformation energy storage capacity to achieve a sealing function without excessively increasing puncture resistance, thus balancing puncture convenience and sealing reliability. If the thickness is too large, the puncture resistance will increase, which is detrimental to the convenience of clinical operation (potentially increasing the risk of needle bending and the difficulty of puncture); if the thickness is too small, the structural deformation energy storage will be insufficient, and the rebound sealing force will be inadequate, which will also affect the sealing effect.

[0043] When the needle passes through the concave structure, the concave surface is geometrically closer to a V-shape or cone. The downward pressure of the puncture needle can then be converted into lateral compressive pressure on the seal 2, resulting in tensile deformation. The restoring force of the V-shaped or cone-shaped channel formed by the stretching of the concave surface will drive the seal 2 to quickly close towards the center of the concave surface after the puncture needle punctures the seal 2, achieving a "self-healing" seal.

[0044] The concave puncture surface combined with the arched convex curved surface structure 3 allows the seal to be maintained for more than 8 hours, which far meets the requirements for infusion sealing.

[0045] The concave curved surface also utilizes the wall-attachment effect of fluid mechanics, with no sharp corners or blind cavities. The TPE melt flows smoothly along the curved surface without eddies or trapped gas. Gas can be uniformly squeezed to the parting surface for discharge, achieving a fit between TPE and the outer cover. This avoids defects such as bubbles and delamination at the bonding surface, significantly improving the product qualification rate.

[0046] Furthermore, the maximum effective chord length D of the sealing element 2 located inside the outer cover 1 is 36mm, and the minimum effective chord length d is 4mm. That is, the maximum and minimum effective chord lengths of the sealing element 2 must match the inner diameter specifications of the standard medical infusion cap, and the effective chord length of the sealing element 2 is in the range of 36mm to 4mm;

[0047] If the maximum effective chord length D is too large, it will be impossible to install or the structure will fail due to compression deformation.

[0048] If the minimum effective chord length d is too small, the arch height of the curved structure 3 will be too low, the deformation energy storage space will be insufficient, and the rebound sealing force generated by the structural deformation will not be able to compensate for the shortness of the material rebound of the sealing component 2.

[0049] The maximum effective chord length D also determines the maximum span of the curved structure 3, directly affecting the rise-to-span ratio (the ratio of arch height to span) of the arch (or spherical structure), and thus affecting the deformation energy storage capacity. The minimum effective chord length d must be greater than the outer diameter of the puncture needle to ensure that the puncture needle can be smoothly inserted and form an effective sealing envelope within the sealing element 2.

[0050] As one of many implementations, the puncture surface 4 is circular or polygonal. The polygonal shape includes, but is not limited to, triangles, rectangles, pentagons, and hexagons. Furthermore, the puncture surface 4 and the outer end face of the outer cover 1 can be located on different planes, for example... Figure 7 As shown, there is a boss on the outer end face of the outer cover 1, and the puncture surface 4 is located on the end face of the boss.

[0051] As one of many embodiments, this application also includes a liquid-blocking membrane 5, which is located inside the outer cover 1 and covers the curved surface structure 3 of the sealing member 2, such as... Figure 5 As shown. Because some drug components may interact with the material of the non-rigid seal 2 (such as TPE), affecting the physical properties of the seal 2 (such as changes in hardness and elastic modulus) or drug stability, a physical isolation barrier needs to be set between the seal 2 and the drug solution. The location and covering method of the liquid-separating membrane must be compatible with the curved structure 3, and must not impede the deformation energy storage function of the curved structure 3 during puncture and the rebound closure function after needle removal.

[0052] Furthermore, the liquid-separating membrane 5 simultaneously covers the inner end faces of the curved structure 3 and the outer cover 1, such as... Figure 6As shown, the liquid-sealing membrane 5 and the outer cover 1 are made of the same material, namely PE, PP, or PP+PE. The outer cover 1, the liquid-sealing membrane 5, and the sealing element 2 are integrally formed using a two-color injection molding process. In traditional solutions, the three components are molded separately and then assembled, resulting in multiple processes, low efficiency, and poor assembly consistency. In this application, the outer cover 1 and the liquid-sealing membrane 5 are made of the same material and can be integrally formed into a single component in the first injection molding process; the sealing element 2 is made of a non-rigid material (such as TPE) and is integrally formed with this component in the second injection molding process. The entire process uses only a two-color injection molding process, requiring no additional assembly steps, resulting in a complete and uniform product structure.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0054] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0055] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be easily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A two-color injection-molded one-piece cap with a domed reinforcing structure, characterized in that, include: The outer cover (1) and the sealing element (2) are non-rigid components. The sealing element (2) is integrally formed with the outer cover (1) by a two-color injection molding process. The sealing element (2) has a curved surface structure (3) at one end facing the inside of the outer cover (1). The curved surface structure (3) is configured to store energy by generating structural deformation when the puncture needle punctures. The sealing element (2) has a puncture surface (4) at one end facing the outside of the outer cover (1). When the puncture needle punctures, the needle tip enters the sealing element (2) through the puncture surface (4) and leaves the sealing element (2) through the curved surface structure (3).

2. The two-color injection-molded integrated cap with an arched reinforcing structure according to claim 1, characterized in that, The curved structure (3) is an arched protrusion, and the two ends of the arched protrusion are connected to the side wall of the seal (2) by a circular arc transition.

3. The two-color injection-molded one-piece cap with an arched reinforcing structure according to claim 1, characterized in that, The curved surface structure (3) is a spherical protrusion, and the edge of the spherical protrusion is connected to the edge of the puncture surface (4).

4. The two-color injection-molded integrated cap with a domed reinforcing structure according to claim 1, characterized in that, The puncture surface (4) is a plane.

5. The two-color injection-molded integrated cap with a domed reinforcing structure according to claim 1, characterized in that, The puncture surface (4) is a concave surface that is recessed into the outer cover (1).

6. The two-color injection-molded one-piece cap with a domed reinforcing structure according to claim 1, characterized in that, The maximum effective chord length D of the seal (2) located inside the outer cover (1) is 36 mm.

7. The two-color injection-molded integrated cap with a domed reinforcing structure according to claim 1, characterized in that, The minimum effective chord length d of the seal (2) located inside the outer cover (1) is 4 mm.

8. The two-color injection-molded one-piece cap with an arched reinforcing structure according to claim 1, characterized in that, The puncture surface (4) is circular or polygonal.

9. The two-color injection-molded one-piece cap with an arched reinforcing structure according to claim 1, characterized in that, It also includes a liquid-blocking membrane (5), which is located inside the outer cover (1) and covers the curved structure (3) of the seal (2).

10. The two-color injection-molded one-piece cap with an arched reinforcing structure according to claim 9, characterized in that, The liquid-blocking membrane (5) and the outer cover (1) are made of the same material. The outer cover (1), the liquid-blocking membrane (5) and the sealing element (2) are integrally formed by two-color injection molding process.

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