Synthetic resin screw cap and mold device for manufacturing the same

Abstract

To improve designability of a screw cap which is easy to open by coating an outer surface of a cap body with an elastomer.SOLUTION: A cap 3 is composed of a cap body 12 made of PP and a covering part 13 made of elastomer. The covering part 13 has a third part 28 located in the center of a top surface and a disk-shaped second part 27 placed separately on the outside. The third part 28 and the second part 27 are connected via a fourth part 29 that overlaps the lower surface of the top plate 15 and a joint part 30 that branches off from the fourth part. The appearance of the elastomer resin flow is magical and unexpected, attracting consumer attention and improving marketability. By providing a retractable center pin 44 on the reversible movable mold 38, the fourth part 29 and the joint part 30 can be realized.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a screw cap made of synthetic resin for use on containers such as pouches and bottles, and a mold apparatus for manufacturing the same. [Background technology]

[0002] Synthetic resin screw caps are widely used as caps for containers such as bottles and pouches. However, because their outer diameters are often set to match the opening diameter of the container, if the opening diameter of the container is small, the outer diameter of the cap also becomes small, making it difficult to rotate.

[0003] In other words, many screw caps for bottles and pouch containers are made from polypropylene or polyethylene and have a knurled portion on the outer surface to provide a good grip for fingers. However, when the cap has a small diameter, for example 20 mm or less, even if a knurled portion is provided, it is not possible to apply a large amount of friction to the cap, resulting in slippage between the finger and the cap, making it difficult to apply the required rotational torque to the cap.

[0004] In particular, when the cap is sealed, the center foot (seal tube) on the cap fits tightly into the opening, making it difficult to open. Furthermore, if the cap is connected to a PP ring (PP band) for sealing, opening the cap requires tearing the bridge connecting the PP ring and the cap body, making opening even more difficult.

[0005] Therefore, as a means to make opening easier, it has been proposed to make the cap body out of polypropylene or polyethylene and to cover the outer surface of the cap body with a soft material to make it easier to grip with the fingers.As an example, Patent Document 1 discloses that a covering made of an elastomer is integrally joined to the cap body by a two-color molding method.

[0006] When a covering portion made of elastomer or the like is integrally molded onto the outer surface of a main body such as a cap, there are two molding methods: insert molding and two-color molding. In the case of a screw cap, however, it is extremely difficult to attach the cap body with an internal thread to a mold. Therefore, as disclosed in Patent Document 1, it is preferable to use two-color molding, in which the covering portion is molded after the cap body is molded without removing it. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 7123319 Summary of the Invention [Problem to be solved by the invention]

[0008] Whether using insert molding or two-color molding, when forming the covering portion in a mold, it is preferable to inject the resin from the center of the top surface of the cap body in order to make the flow of resin uniform and achieve accurate molding. From this perspective, in Patent Document 1, the covering portion has a radial portion located on the top surface of the cap and a peripheral wall portion located on the outer circumferential surface of the cap, and the radial portion and the wall portion are continuous.

[0009] The covering portion made of elastomer can cover the entire outer circumference and the entire top surface of the cap body, but if the covering portion is formed radially on the top surface as in Patent Document 1, there are advantages such as being able to reduce the amount of elastomer used and being able to improve the appearance by using a different color from the cap body.

[0010] However, in Patent Document 1, the radial portions on the top surface of the cap body spread out from the center, which is considered to lack a sense of surprise in terms of design and not be visually appealing enough to consumers. Also, because the radial portions merely overlap the top surface (groove portion) of the cap body, there are concerns that they may lift after molding or may curl up if hit hard by an object.

[0011] The present invention was made against this background and aims to disclose an improved technology for providing a covering portion to facilitate opening, which has excellent designability and peel resistance. [Means for solving the problem]

[0012] The present invention includes various configurations, and typical configurations are specified in each claim. Of these, the invention of claim 1 is directed to a screw cap made of synthetic resin, "The cap has a cylindrical portion and a top plate, and is screwed onto the mouth of a container from the outside. The cap also has a covering portion that is integral with the cap, facilitating the rotation of the cap. The covering portion has a first portion overlapping the outer peripheral surface of the cap body, a second portion overlapping the upper surface of the cap body while being continuous with the first portion, a third portion disposed through the center of the top plate without being continuous with the second portion, and a fourth portion disposed on the lower surface of the top plate and continuous with the third portion, and the fourth portion and the second portion are connected via a joint portion that penetrates the top plate. The structure is as follows.

[0013] The invention of claim 2 is a development example of claim 1, "The first portion of the covering portion has a plurality of longitudinal ribs arranged separately in the circumferential direction and a lower ring connected to the lower ends of the plurality of longitudinal ribs, The second portion is annular and continuous with the first portion. The structure is as follows.

[0014] The invention of claim 3 is a development example of claim 2, "The cylindrical portion of the cap body is formed into a polygon having five or more sides in plan view, and the vertical ribs of the first portion are disposed on the ridges of the polygon." The structure is as follows.

[0015] The invention of claim 4 is an expansion of any of claims 1 to 3, "A center hole, which is closed by the third portion of the covering portion, is opened in the center of the top plate of the cap body, and a plurality of center bridges are disposed inside the center hole, extending radially from the center when viewed in the axial direction to the inner circumferential surface of the center hole, and the plurality of center bridges are embedded in the third portion of the covering portion." The structure is as follows.

[0016] The invention of claim 5 is also a development example of any of claims 1 to 3, "The cap body is made of polypropylene or polyethylene, and the covering part is made of elastomer, and is used for pouch containers, bottles, metal cans, and paper cartons." The structure is as follows.

[0017] The screw caps of claims 1 to 5 can be easily manufactured by the mold device specified in claim 6. That is, this mold device is "The cap body has a first fixed mold that forms the outer surface of the cap body, a second fixed mold that forms the covering portion, and a reversible movable mold that forms the inside of the cap body, and the reversible movable mold can be selectively brought into close contact with either the first fixed mold or the second fixed mold, the reversible movable die has a center pin that forms a portion of the inner surface of the top plate where the second portion of the covering portion overlaps, and the center pin is freely movable forward and backward in the axial direction, while the first fixed die has a downward protrusion for forming a joint passage corresponding to the joint portion, In the first step of molding the cap body by placing the reversible movable mold on the first fixed mold, the center pin advances and a downward projection of the first fixed mold abuts against a part of the center pin, and in the second step of molding the covering part by placing the reversible movable mold on the second fixed mold, the center pin retreats and a space for forming the fourth part is created. The structure is as follows. [Effects of the Invention]

[0018] In the present invention, the top surface of the cap is free from the covering portion around the third portion, leaving the cap body exposed, and the second portion of the covering portion extends radially outward from the exposed portion of the cap body. The unexpectedness of the covering portion extending on the top surface catches the consumer's eye and leaves an impression on them as a unique design. Therefore, the design can improve the product value.

[0019] Furthermore, because the fourth part is located on the underside of the top plate, even if a strong external force acts on the second or third part, the fourth part exerts a strong anchoring effect, preventing the second or third part from curling up and preventing the second or third part from floating up after molding. This ensures high precision and improves quality.

[0020] The first part of the covering part can cover the entire outer periphery of the main body, but if the vertical ribs are arranged separately in the circumferential direction as in claim 2, the contrast with the exposed part of the cap main body creates a sharp appearance, which enhances aesthetics and increases the product value. It also makes it easier to open by providing a good grip for fingers.

[0021] Furthermore, since the upper ends of the multiple vertical ribs are continuous with the annular second part and the lower ends are connected to the lower ring, even if a circumferential external force acts on the vertical ribs when the cap is rotated, the first part will not be rolled up, and high quality can be maintained.

[0022] Forming the cap body into a polygon as in claim 3 can further increase the grip of fingers and make opening easier, but the ridges where fingers come into strong contact are made up of the covering part, which increases friction with the fingers and makes opening even easier. The gate mark on the cap body is hidden by the third part of the covering part, so people's fingertips will not come into contact with the gate mark on the cap body, making it safe.

[0023] In the invention of claim 4, the gate position for molding the cap body and the gate position for molding the covering portion can be positioned in the center of the top plate, so that the resin can be spread evenly on both the cap body and the covering portion, ensuring high molding precision.

[0024] As mentioned above, polypropylene or polyethylene is generally used as the material for the cap body, but it is preferable that the covering portion be as soft as possible. In this regard, using an elastomer (thermoplastic elastomer) as in claim 5 is preferable because it improves finger grip without impairing moldability. There are many types of thermoplastic elastomers, and various materials such as olefin-based, styrene-based, polyurethane-based, and polyester-based materials can be used.

[0025] The screw cap of the present invention can be manufactured by a two-color molding method using a mold device with two fixed molds and one reversible movable mold. However, in the two-color molding method, the underside of the top plate that constitutes the cap body is formed using a reversible movable mold, so a normal two-color molding mold device cannot be used to manufacture the product of the present invention, in which the fourth part of the covering overlaps the underside of the top plate.

[0026] However, in the present invention, by providing a retractable center pin on the reversible movable mold as in claim 6, a screw cap having a fourth section and a joint section can be easily manufactured by a normal two-color molding method. Therefore, the invention of claim 6 makes it possible to easily manufacture a screw cap with excellent design and peel resistance. [Brief explanation of the drawings]

[0027] [Figure 1] 1A and 1B are diagrams showing the first embodiment, in which (A) is a front view of the screw cap separated from the dispensing device, (B) is a front view of the screw cap attached to the dispensing device (sealed state), (C) is a longitudinal front view, and (D) is a bottom view of (B). [Figure 2]1A and 1B are diagrams showing the first embodiment, in which (A) is a plan view of the cap body, (B) is a front view of the cap body, (C) is a bottom view of the cap body, (D) is a plan view of the covering part, (E) is a longitudinal front view of the covering part, (F) is a cross-sectional view of (E) taken along the FF line, and (G) is a longitudinal front view of the cap body. [Figure 3] (A) is a schematic perspective view of the first embodiment, (B) is a diagram showing the molding process of the cap body, (C) is a cross-sectional view taken along CC in (B), (D) is a diagram showing the molding process of the covering portion, (E) is a cross-sectional view taken along EE in (D), and (F) is a diagram showing another example of a joint passage. [Figure 4] FIG. [Figure 5] 10A is a plan view of the second embodiment, FIG. 10B is a front view of the second embodiment, FIG. 10C is a plan view of the third embodiment, and FIG. 10D is a front view of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] (1) Basic structure of the first embodiment Next, embodiments of the present invention will be described with reference to the drawings. This embodiment is applied to a screw cap of a pouch container. First, a first embodiment shown in Figures 1 to 3 will be described. The pouch container is composed of a bag body 1 made of a laminated film, a dispensing device 2 attached to the upper end of the bag body 1, and a screw cap 3 for opening and closing the dispensing device 2.

[0029] The bag body 1 is formed in a generally rectangular shape with the top and bottom longer when viewed from the front, and the dispensing device 2 is attached to the middle part of the top of the bag body 1. The bag body 1 can be, for example, a standing pouch made of three films: front and back films and a bottom film. Alternatively, various structures can be adopted, such as a non-standing type (hanging type) that does not have a bottom film, or a gusset-folded type.

[0030] As shown in Figure 1, the dispensing device 2 includes a welding portion 4 to which the bag body 1 is welded, and a dispensing tube 5 that is integrally connected to the welding portion 4 and exposed above the bag body 1. The dispensing tube 5 is formed with a male thread 6 onto which a screw cap (hereinafter simply referred to as "cap") 3 is screwed, an upper flange 7 located below the male thread 6, and a lower flange 8 connected to the upper end of the welding portion 4. The two elements, the welding portion 4 and the dispensing tube 5, can be collectively referred to as the spout body. The male thread 6 is a double-start thread, but may also be a single-start or triple-start thread.

[0031] The welded portion 4 is shaped like an eye when viewed in the axial direction. Therefore, when the welded portion 4 is used as a reference, the dispensing device has a longitudinal direction and a width direction (short direction), and the cap 3 is rotated while the welded portion 4 is pinched from the width direction.

[0032] The welded portion 4 has three horizontal ribs 9 extending in a direction transverse to the axis and vertical ribs 10 connected to the tips of the horizontal ribs 9. The bottom flange 8, which is continuous with the welded portion 4, has an elongated hexagonal shape when viewed in the axial direction. The bottom flange 8 also functions as a stopper that positions the upper end of the bag body 1.

[0033] The upper flange 7 is circular, and when transported on a filling line or the like, the area between the upper and lower flanges 7, 8 is sandwiched between a pair of chutes. Therefore, the pouch container is transported with the upper flange 7 resting on the chute. A position-maintaining plate 11 is provided between the upper and lower flanges 7, 8 to prevent the pouch container from rotating during transport on the chute (the area between the upper and lower flanges 7, 8 may be formed into a square when viewed in the axial direction).

[0034] The dispensing device 2 is manufactured by injection molding using synthetic resin such as polypropylene or polyethylene, and the mold device for manufacturing the dispensing device 2 has a fixed mold (cavity) and a movable mold (core) that move relative to each other in the axial direction as basic molds, but because the dispensing device 2 has ribs 9, 10, flanges 7, 8, and male thread 6, a pair of split molds that move relative to each other in the left-right direction perpendicular to the axial direction are also used. This point is conventionally known.

[0035] (2) Cap of the first embodiment The cap 3 is composed of a cap body 12 made of polypropylene (PP) or polyethylene and an elastomer covering part 13. The cap body 12 has a cylindrical part 14, a top plate 15 integrally connected to the upper end of the cylindrical part 14, and a PP ring (PP band) 17 integrally connected to the lower end of the cylindrical part 14 via multiple bridges 16a and 16b.

[0036] The PP ring 17 is divided into two parts via a pair of breakable lower bridges 17a, and the two divided PP rings 17 are connected to the lower end of the tubular portion 14 by an unbreakable upper bridge 16a and a breakable upper bridge 16b, respectively. As shown in Figures 1(C) and 2(G), a group of ratchet pawls 18a is provided on the inner periphery of the PP ring 17. A group of engagement protrusions 18b that engage with the ratchet pawls 18a is provided upward on the upper flange 7 of the dispensing device 2.

[0037] The ratchet pawl 18a and the engaging protrusion 18b are designed not to engage in the screw-in rotation direction (they elastically deform and move away), but to engage (interlock) in the unscrewing direction. Therefore, the cap 3 can be screwed on after filling the bag 1, and when unscrewing it to open it, the PP ring 17 does not rotate, and the breakable upper bridge 16b and lower bridge 17a are torn off. This provides a sealing function.

[0038] A female thread 14a is formed on the inner periphery of the cylindrical portion 14 of the cap body 12, and a plurality of (six) vertically elongated ridges 19 are formed at equal intervals on the outer periphery of the cylindrical portion 14. A circular rear flange 20 that forms the lower end surface of the cap 3 is formed at the lower end of the cylindrical portion 14, and the above-mentioned PP ring 17 is connected to the rear flange 20 via upper bridges 16a and 16b. As shown in FIG. 2(A), the vertically elongated ridges 19 are located inside the rear flange 20. In other words, there is a slight step of dimension E between the protruding end of the vertically elongated ridges 19 and the outer periphery of the rear flange 20.

[0039] In the cap body 12, the connecting portion between the tube portion 14 and the top plate 15 forms a tapered surface 21. Furthermore, a cylindrical center leg (sealing tube) 22 that fits tightly against the inner surface of the dispensing tube 5 is formed on the lower surface of the top plate 15, and a circular center boss 23 that is positioned more inward than the center leg 22 in plan view is formed on the upper surface of the top plate 15, and multiple (three) joint passages 24 penetrate a ring-shaped area surrounded by the center leg 22 and the center boss 23 in plan view.

[0040] As shown in Figures 2(A) and 2(G), the center boss 23 has a circular center hole 23a inside, and a center bridge 25 that is connected integrally to the inner surface of the center boss 23 and has a three-arrow shape in plan view is located in the lower half of the center hole 23a. The center bridge 25 may also have a straight or cross shape in plan view. In either case, it is preferable that it extends radially from the center of the top plate 15. The bottom end surface of the center bridge 25 is flush with the bottom end surface of the top plate 15, but it may be slightly raised above the bottom surface of the top plate 15.

[0041] The covering portion 13 is intended to provide a good grip for fingers when opening and closing the cap 3. Therefore, it has, as an essential element, a first portion 26 that overlaps the outer peripheral surface of the tubular portion 14 of the cap body 12, a ring-shaped second portion 27 that is continuous with the first portion 26 and is located outside the center boss 23 on the upper surface of the top plate 15, a third portion 28 that fills the center hole 23a and passes through the top plate 15, and a fourth portion 29 that overlaps a portion of the lower surface of the top plate 15 that is surrounded by the midfoot 22, and the fourth portion 29 and the second portion 27 are connected together by a joint portion 30 that fills the joint passage 24.

[0042] In the embodiment, the fourth part 29 is in the shape of a disk that fills the inside of the midfoot 22, but it can also be in a form that extends radially from the third part 28 toward each joint part 30 (in this case, it is preferable that the third part 28 and the fourth part 29 are configured to fit into a groove (recess) formed in the underside of the top plate 15).

[0043] The first portion 26 of the covering portion 13 has a through hole 31 through which the vertically elongated ridges 19 of the cap body 12 are exposed. The first portion 26 also has a group of vertically elongated ribs 32 that protrude radially between adjacent vertically elongated ridges 19. Corresponding to the tapered surface 21 formed at the upper end of the cap body 12, the covering portion 13 also has a tapered surface 33 formed at the junction between the first portion 26 and the second portion 27, and the tapered surface 33 has upward converging portions 32a of the vertically elongated ribs 32 formed thereon.

[0044] A lower ring 34 having the same diameter as the rear flange 20 of the cap body 12 is integrally formed at the lower end of the first portion 26. Because the lower ring 34 holds the entire circumference of the cap body 12, the first portion 26 will not be turned up by an external force even though it has a through-hole 31. In Figure 3, the cap body 12 made of PP is shaded to clearly show the contrast with the covering portion 13 made of elastomer.

[0045] (3) Cap 3 molding device and molding method (manufacturing method) The cap 3 is manufactured using the mold device shown in Figures 3(B) to (E). That is, the mold device is a mold device for two-color molding, and has a first fixed mold (first cap) 36 that forms the outer surface of the cap body 12, a second fixed mold (second cap) 37 that forms the covering portion 13, and a reversible movable mold (reversible core) 38 that forms the interior of the cap body 12. The reversible movable mold 38 is attached to a movable plate 39.

[0046] The first fixed mold 36 and the second fixed mold 37 are attached to a fixed member of the molding machine so as to be separated vertically and horizontally. On the other hand, the movable unit having the reversible movable mold 38 and the movable plate 39 is reversible so as to selectively face either the first fixed mold 36 or the second fixed mold 37, and is attached to the molding machine so as to be able to freely come into contact with or separate from the first fixed mold 36 or the second fixed mold 37.

[0047] As shown in FIG. 3(B), the first fixed mold 36 has a first space (cavity) 40 that forms the outer surface of the cap body 12. This embodiment is characterized by a three-arrow-shaped center space 41 for forming the center bridge 25 and a downward protrusion 42 for forming the joint passage 24. A first gate 43 of the first fixed mold 36 opens into the center space 41. Therefore, the resin is injected into the first space 40 from the center. Therefore, the resin spreads evenly throughout the first space 40. This allows the cap body 12 to be molded with high precision.

[0048] On the other hand, the reversible movable mold 38 has an outer shape that fits into the inner surface of the cap body 12, but as a structure unique to this embodiment, it has a center pin 44 with the same diameter as the inner diameter of the center leg 22 of the cap body 12. The center pin 44 is movable back and forth in the axial direction of the cap 3 (the direction of clamping and opening the reversible movable mold), and in the first step of molding the cap 3 by bringing the reversible movable mold 38 into close contact with the first fixed mold 36, the center pin 44 is advanced and forms the inner surface of the top plate 15 as well.

[0049] 3(D), a second space 45 for forming the covering portion 13 is formed in the second fixed mold 37. Then, in the second step in which the reversible movable mold 38 with the cap body 12 still attached is brought into close contact with the second fixed mold 37, the center pin 44 is retracted. Then, a tunnel space 46 corresponding to the fourth portion 29 of the covering portion 13 is formed between the top plate 15 of the cap body 12 and the center pin 44, and the tunnel space 46 communicates with the center hole 23a and the joint passage 24.

[0050] Therefore, when molten elastomer resin is injected into center hole 23a through second gate 47, the elastomer resin spreads throughout second space 45 via center hole 23a, tunnel space 46, and joint passage 24, and covering portion 13 is formed in a state where it is integrally joined with cap body 12. Because second gate 47 is located at the center of second space 45 when viewed in the axial direction, the elastomer resin spreads evenly throughout second space 45, allowing covering portion 13 made of elastomer to be formed with high precision.

[0051] (4) Summary Pouch containers have a wide range of uses. In the case of pouches containing fluid foods such as jelly-like foods, where the consumer holds the dispensing tube 5 in their mouths to suck up the contents, the outer diameter of the dispensing tube 5 is approximately 12 mm to ensure ease of gripping. Even when packaging non-food fluids, the outer diameter of the dispensing tube 5 may be approximately 12 mm. The outer diameter of the cap 3 varies in proportion to the outer diameter of the dispensing tube 5. However, when the outer diameter of the dispensing tube 5 is approximately 12 mm, the outer diameter of the cap 3 is generally approximately 15 mm. Therefore, even when a person grasps the cap firmly, the cap is prone to slippage, making it difficult to open. This is particularly true for consumers with limited strength, such as women and children, whose fingers tend to slip due to their weak grip.

[0052] In contrast, in this embodiment, the outer peripheral surface of the cap body 12 is configured with the first portion 26 of the covering portion 13 made of elastomer, which significantly improves the grip of fingers. Therefore, even consumers with little strength, such as women and children, can apply a strong torque to the cap 3 and open it with little force.

[0053] The cap body 12 and the covering portion 13 are not only different in texture due to the difference in materials, but also in color, making them clearly visible. However, on the top surface of the cap 3, the third portion 28 of the covering portion 13 made of elastomer, the top plate 15 of the cap body 12 made of PP, and the second portion 27 of the covering portion 13 made of elastomer extend concentrically, resulting in an unprecedented and excellent design that attracts consumers' attention. This improves the product value. In other words, high evaluation of the design of the cap 3 can stimulate purchasing desire for pouch products.

[0054] In this type of cap 3, when the covering portion 13 made of elastomer is molded by two-color molding, the gate is usually positioned at the center of the top plate 15. For this reason, in Patent Document 1, the elastomer layer extends radially from the center of the top plate, and it can be seen that it was molded using a normal method and mold, but in this embodiment, it is not clear how the elastomer is diffused, which makes it magical and can be said to create a strong sense of surprise for consumers and attract their attention.

[0055] In this embodiment, the cap 3 is polygonal (hexagonal) and each ridge is made of elastomer, further improving the grip of the fingers. Furthermore, the PP constituting the cap body 12 is exposed on the flat surface, which does not contribute much to the grip of the fingers, resulting in a sharp appearance without compromising ease of opening. As mentioned above, the lower ring 34 prevents the cap from rolling up, but since it can prevent rolling up, a softer elastomer can be used, further improving ease of opening.

[0056] As shown in FIG. 3(F), if the joint passage 24 is formed in a shape that widens toward the outer periphery, the flow of the elastomer resin can be promoted.

[0057] In the present invention, the shape of the cap 3 and the shape of the covering portion 13 can be developed in various ways. For example, in the second embodiment shown in Figures 5(A) and (B), the cap 3 has a basic shape of a normal hexagon without tapered surfaces, but the second portion 27 is formed closer to the outer periphery. Therefore, the exposed area of ​​the top plate 15 made of PP is larger than in the first embodiment. In addition, the second portion 27 has a narrow portion 27a extending from the joint portion 30. In this embodiment, the hexagonal ridge portion is also formed by a vertically elongated rib 32.

[0058] 5(C) and 5(D), the cap body 12 is formed in a circular shape, and a high knurled portion 48 is formed on the outer periphery. Therefore, the entire outer periphery of the cap body 12 is covered with the first portion 26 of the covering portion 13. The second portion 27 of the covering portion 13 extends further outward than in the second embodiment, and the exposed area of ​​the PP on the top surface of the cap 3 is larger than the exposed area of ​​the elastomer.

[0059] It is also possible to form the cap 3 in a polygonal shape such as a hexagon, and form a knurled portion with fine indentations all over the first portion 26. Furthermore, the cap 3 can be formed in an oval or elliptical shape that is close to a perfect circle, which further reduces finger slippage and improves ease of opening. If the first portion of the covering has vertical ribs that are separated from each other, it is also possible to form the upper end of the first portion into a closed loop, and form the second portion radially.

[0060] It is also possible to make the cap body from high-density polyethylene and the covering from low-density polyethylene or an olefin-based elastomer, in which case the cap body and covering are made of the same material, making them easier to recycle after disposal.It is also possible to use low-density polyethylene as the covering and add a considerable amount of plasticizer to ensure softness equivalent to that of elastomer.

[0061] Although the cap in the embodiment is equipped with a PP ring, the present invention can also be applied to caps without a PP ring. Furthermore, while the embodiment is applied to a cap for a pouch container, the present invention can also be applied to caps for PET bottles, various resin containers, bottles such as glass bottles, and can containers. Furthermore, while the screw cap of the present invention can be manufactured by insert molding, two-color molding is preferred in terms of labor, precision, and reliability.

[0062] As mentioned above, the first and second parts of the covering can be arbitrarily shaped. For example, the inner periphery of the second part can be rectangular or star-shaped (in which case, the outer periphery of the exposed part of the top plate in the main body will also be rectangular or star-shaped). [Industrial Applicability]

[0063] The present invention is applicable to screw caps and their manufacturing techniques, and is therefore industrially applicable. [Explanation of symbols]

[0064] 1. Bag body constituting the pouch container 2 Dispensing device 3 screw caps 4 Welded area 5 Pour tube 6 Male thread 7 Upper flange 12 Cap body 13 Covering part 14 Cylinder 15 Top plate 19 Vertical convex strips 22 midfoot 23 Center Boss 23a center hole 24 Cap body joint passage 25 Center Bridge 26 First part of the covering 27 Second part of the covering 28 Third part of the covering 29 Fourth part of the covering 30 Joint of the covering part 32 Vertical rib 33 Tapered surface 34 Lower Ring 36 1st fixed type 37 Second fixed type 38 Reversible Movable Type 40 First space that becomes the cap body 43 Gate 1 44 center pin 45 Second space that becomes the covered part 46 Tunnel Space 47 Gate 2

Claims

1. The cap includes a cap body having a cylindrical portion and a top plate and being screwed onto the mouth of a container from the outside, and a covering portion integrally provided on the cap body to facilitate rotational operation, The covering portion has a first portion overlapping the outer peripheral surface of the cap body, a second portion overlapping the upper surface of the cap body while being continuous with the first portion, a third portion disposed through the center of the top plate without being continuous with the second portion, and a fourth portion disposed on the lower surface of the top plate and continuous with the third portion, and the fourth portion and the second portion are connected via a joint portion that penetrates the top plate. Synthetic resin screw cap.

2. The first portion of the covering portion has a plurality of longitudinal ribs arranged separately in the circumferential direction and a lower ring connected to lower ends of the plurality of longitudinal ribs, The second portion is formed in an annular shape and is continuous with the first portion.

2. The synthetic resin screw cap according to claim 1.

3. The cylindrical portion of the cap body is formed in a polygonal shape having five or more sides in a plan view, and the vertical rib of the first portion is disposed on a ridge line portion of the polygon.

3. The synthetic resin screw cap according to claim 2.

4. a center hole that is closed by the third portion of the covering portion is opened in the center of the top plate of the cap body, and a plurality of center bridges are disposed inside the center hole, extending radially from the center as viewed in the axial direction to reach the inner peripheral surface of the center hole, and the plurality of center bridges are embedded in the third portion of the covering portion; A synthetic resin screw cap according to any one of claims 1 to 3.

5. The cap body is made of polypropylene or polyethylene, and the covering portion is made of elastomer, and is used for any of pouch containers, bottles, metal cans, and paper packs. A synthetic resin screw cap according to any one of claims 1 to 3.

6. A mold apparatus for manufacturing the screw cap according to any one of claims 1 to 5, a first fixed mold forming an outer surface of the cap body, a second fixed mold forming the covering portion, and a reversible movable mold forming an interior of the cap body, wherein the reversible movable mold can be selectively brought into close contact with either the first fixed mold or the second fixed mold; the reversible movable die has a center pin that forms a portion of the inner surface of the top plate where the second portion of the covering portion overlaps, and the center pin is freely movable forward and backward in an axial direction, while the first fixed die has a downward protrusion for forming a joint passage corresponding to the joint portion, In a first step of molding the cap body by placing the reversible movable mold on the first fixed mold, the center pin is advanced so that a downward protrusion of the first fixed mold abuts against a part of the center pin, and in a second step of molding the covering part by placing the reversible movable mold on the second fixed mold, the center pin is retreated so that a space for forming the fourth part is opened. Mold equipment for manufacturing screw caps.

Images