Plastic caps and containers

Abstract

The present invention provides a resin cap and container that can adopt a shape that allows for weight reduction while ensuring moldability. [Solution] In a resin cap 200 having a cylindrical portion 38 connected to a top portion 31, the top portion 31 has a central top portion 33, a base portion 37 whose outer edge is connected to the upper end of the cylindrical portion and which is located closer to the cylindrical portion 38 than the central top portion 33, and a connecting portion 35 that connects the outer edge of the central top portion 33 and the inner edge of the base portion 37. The thickness T1 of the central top portion 38 and the thickness T2 of the connecting portion 35 are the same. The thickness T3 of the base portion 37 is about the same as or the same as the thicknesses T1 and T2.

Description

Technical Field

[0004]

[0001] The present invention relates to a resin cap and a container.

Background Art

[0002] A resin cap attached to the mouth of a container for storing beverages or the like generally has a cylindrical portion extending from the periphery of the top portion and is formed of a thermoplastic resin. A screw portion is formed on the inner peripheral surface of the cylindrical portion, and an inner plug and an outer plug are formed on the lower surface of the top portion. When closing the mouth, these plugs sandwich the upper end of the mouth in the radial direction to seal the mouth, and the screw portion is screwed into the screw portion on the outer peripheral surface of the mouth (see, for example, Patent Document 1).

[0003] Since such existing caps have a simple shape, compression molding is generally used as the molding method.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0007] The present invention aims to provide a resin cap and container that can adopt a shape that allows for weight reduction of the container while ensuring moldability. [Means for solving the problem]

[0008] A resin cap according to one aspect of the present invention has a cylindrical portion connected to the top, the top portion having a central apex, a base portion whose outer edge is connected to the upper end of the cylindrical portion and which is located closer to the cylindrical portion than the central apex, and a connecting portion connecting the outer edge of the central apex and the inner edge of the base portion, the central apex and the connecting portion having the same thickness, and the connecting portion having the same thickness as or about the same thickness as the central apex and the base.

[0009] According to this embodiment, since the cap has a stepped shape overall in the top and cylindrical portions, a shape that accommodates container weight reduction can be adopted (for example, a shape that lowers the sealing point without changing the height of the cap by forming an inner plug on the underside of the top portion). Furthermore, because the wall thickness of the stepped portions, namely the central top, base, and connecting portion, is set as described above, the softened molding material (resin) flows more smoothly within the mold during cap molding. This ensures moldability. [Brief explanation of the drawing]

[0010] [Figure 1] This is a front view of the container body of the container according to the embodiment. [Figure 2] This is a cross-sectional view showing a magnified view of the opening of the container body in Figure 1. [Figure 3] This is a perspective view of the cap according to the embodiment, cut along a vertical plane including the central axis. [Figure 4]Figure 3 is a cross-sectional view showing the cap in the state of closing the opening shown in Figure 2. [Figure 5] Figure 3 is an enlarged cross-sectional view of one side of the cap. [Figure 5A] This is an enlarged cross-sectional view of one side of a cap according to another embodiment. [Figure 6] Figure 3 is an enlarged view of the outer surface of the cap. [Figure 7] This diagram shows the relationship between the inner plug and the opening of the container body according to the embodiment during the initial stage of the screw-in operation. [Figure 8] This diagram shows the relationship between the inner plug and the opening of the container body in the comparative example during the initial stage of the screw-in operation. [Figure 9] This diagram shows the relationship between the cap according to the embodiment and the mouth of the container body during the initial stage of the screw-on operation. [Figure 10] This diagram shows the relationship between the cap and the mouth of the container body in the comparative example during the initial stage of the screw-on operation. [Modes for carrying out the invention]

[0011] A preferred embodiment of the present invention will be described with reference to the attached drawings. The same reference numerals are used for identical elements, and redundant descriptions are omitted. Furthermore, unless otherwise specified, positional relationships such as top, bottom, left, and right are based on those shown in the drawings. Moreover, the dimensional ratios in the drawings are not limited to those shown.

[0012] A container with a cap according to this embodiment can store various liquids inside, such as beverages, detergents, soaps, shampoos, and sauces. Beverages can include non-carbonated beverages such as water, tea, or fruit juice, as well as carbonated beverages. The container can be made of a metal such as aluminum or stainless steel, or of resin. Similarly, the cap can be made of a metal such as aluminum or stainless steel, or of resin. Below, a plastic beverage bottle will be described as an example of a container, and a resin cap as an example of a cap.

[0013] As shown in Figure 1, the plastic bottle 1 (hereinafter referred to as "bottle 1") has, from top to bottom, a mouth portion 2, a shoulder portion 3, a body portion 4, and a bottom portion 5. These parts (2, 3, 4, 5) are integrally formed to constitute a bottomed cylindrical container body 6 for storing beverages inside. The container body 6 is filled with a beverage, and the mouth portion 2 is closed with a cap 200 (see Figure 4).

[0014] Bottle 1 is molded using a stretch molding method such as biaxial stretch blow molding, primarily from a thermoplastic resin such as polyethylene, polypropylene, or polyethylene terephthalate. An example of the manufacturing process for Bottle 1 is described below. First, thermoplastic resin is injected into a mold to injection mold a preform. The preform consists of a mouth portion with the same shape as the mouth portion 2 and a bottomed cylindrical portion connected to the lower side of the mouth portion. After injection molding, the preform is set in a blow molding machine and the cylindrical portion of the preform is heated. Then, the cylindrical portion is stretched vertically with a stretch rod and stretched horizontally by blowing compressed air into it. The stretched cylindrical portion is pressed against the inner surface of the mold and then solidified. This forms the shoulder portion 3, the body portion 4, and the bottom portion 5, completing the series of moldings for Bottle 1.

[0015] As shown in Figure 2, the opening 2 has a cylindrical peripheral wall 10 with an open upper end. The peripheral wall 10 has a top surface 11 that constitutes the upper end surface, an outer peripheral surface 12 extending from the top surface 11, and an inner peripheral surface 14 extending from the top surface 11. The top surface 11 is, for example, a flat surface. On the outer peripheral surface 12, a threaded portion 16, a bead ring 18, and a support ring 20 are formed to protrude in order from the top surface 11 side. On the other hand, the inner peripheral surface 14 extends straight in the vertical direction without any steps. The threaded portion 16 can be composed of a single-start thread, a double-start thread, or a triple-start thread.

[0016] Here, the height of the mouth part 2 is lower than that of a general mouth part for the purpose of reducing the weight of the container body 6. For example, while the height of a general mouth part is 21 mm, the height of the mouth part 2 here is about 17 mm. The weight of the mouth part 2 with such a short height (for example, about 2.1 g) is considerably smaller than the weight of a general mouth part (about 4 g).

[0017] Next, referring to FIGS. 3 to 5, the outline of the cap 200 will be described.

[0018] The cap 200 is configured as a so-called screw cap and is configured to be able to close the mouth part 2 by a screwing operation with respect to the mouth part 2 of the container body 6 (generally, rotating the cap 200 clockwise).

[0019] The cap 200 is formed mainly of a thermoplastic resin such as polyethylene or polypropylene. As a method for forming the cap 200, for example, injection molding or compression molding can be used.

[0020] The cap 200 has a cap body 30 and a tamper-evident band 40. The cap body 30 has a top part 31 and a cylindrical part 38 connected to the top part 31. When closed, the top part 31 covers the upper part of the mouth part 2, and the cylindrical part 38 covers the side part of the mouth part 2. The cylindrical part 38 has a screw part 39 on its inner peripheral surface for screwing with the mouth part 2 (screw part 16) of the container body 6. Further, the cap body 30 has a maximum outer diameter part 45 connected to the lower end of the cylindrical part 38. The maximum outer diameter part 45 is cylindrical and has no irregularities on its outer peripheral surface.

[0021] The tamper-evident band 40 is separably connected to the lower end of the maximum outer diameter part 45. Specifically, the tamper-evident band 40 is connected to the maximum outer diameter part 45 via a separable bridge 41. On the inner peripheral surface of the tamper-evident band 40, a nib 42 is formed facing inward upward.

[0022] An outer plug 50 and an inner plug 70 are formed on the lower surface of the top portion 31, extending downward. The outer plug 50 protrudes annularly from the lower surface of the top portion 31, with a small gap between it and the inner circumferential surface of the cylindrical portion 38. The cross-sectional shape of the outer plug 50 is arbitrary, but here it is formed in an inverted trapezoid shape when viewed from the front. The inner plug 70 is located on the inner diameter side (towards the YY side of the central axis of the cap 200) than the outer plug 50, is longer than the outer plug 50, and protrudes annularly from the lower surface of the top portion 31. The inner plug 70 extends slightly outward from the top portion 31 before bending inward at the bending point 71 (see Figure 5). A small projection 55 is formed between the outer plug 50 and the inner plug 70. The small projection 55 has a shorter protruding length than the plugs 50 and 70 and is formed annularly on the lower surface of the top portion 31.

[0023] When the cap 200 closes the opening 2, the upper end of the opening 2 is sandwiched radially by the outer plug 50 and the inner plug 70, and the opening 2 is sealed by the cap 200. Specifically, the threaded portion 39 and the threaded portion 16 are screwed together, and the small projection 55 makes contact so as to be pressed against the top surface 11. The outer plug 50 also makes contact from the lower side of the corner portion connecting the top surface 11 and the outer peripheral surface 12 to the straight surface of the outer peripheral surface 12. On the other hand, the inner plug 70 makes contact with the inner peripheral surface 14 at the bent portion 71.

[0024] On the other hand, when the cap 200 is rotated in the opening direction from this closed state, the bridge 41 breaks, the tamper-evident band 40 is separated from the cap body 30, and falls onto the upper surface of the support ring 20. After falling, the tamper-evident band 40 is held between the support ring 20 and the bead ring 18, and is prevented from coming out upward by the nib 42.

[0025] Next, the stepped structure of the cap 200 will be described in detail with reference to Figures 3-5.

[0026] The top portion 31 has a step. Specifically, the top portion 31 has, from top to bottom, a central apex 33, a connecting portion 35, and a base portion 37, with the connecting portion 35 connecting the outer edge of the central apex 33 and the inner edge of the base portion 37. The base portion 37 is located closer to the cylindrical portion 38 than the central apex 33, and the outer edge of the base portion 37 is connected to the upper end of the cylindrical portion 38. The central apex 33 is formed in a disc shape, and the connecting portion 35 is formed in a cylindrical shape. The base portion 37 is also formed in an annular shape, concentric with the central apex 33.

[0027] The central apex 33 and the base 37 extend horizontally, perpendicular to the central axis YY of the cap 200. With respect to this horizontal extension, the central apex 33 is set to be longer than the base 37. On the other hand, the connecting portion 35 that connects the central apex 33 and the base 37 extends in a direction parallel to the central axis YY of the cap 200. Therefore, in the stepped structure of the top portion 31, the central apex 33 and the connecting portion 35 intersect at a substantially 90-degree angle, and the base 37 and the connecting portion 35 also intersect at a substantially 90-degree angle.

[0028] In other embodiments, the central apex 33 and the base 37 do not have to be parallel to each other. For example, the central apex 33 may extend perpendicular to the central axis YY of the cap 200, while the base 37 may be inclined downward toward the outside. Also, the connecting portion 35 does not have to extend parallel to the central axis YY of the cap 200. For example, the connecting portion 35 may be formed in the shape of a frustoconical pyramid and inclined outward toward the bottom. Alternatively, the connecting portion 35 may be formed as a dome-shaped circumferential surface (i.e., a curved surface).

[0029] Here, the walls of each part constituting the top portion 31 are formed with a constant or approximately constant thickness. In one embodiment, the thickness T1 of the central top portion 33, the thickness T2 of the connecting portion 35, and the thickness T3 of the base portion 37 are all the same. These thicknesses T1, T2, and T3 are, for example, 0.6 mm. In another embodiment, the thicknesses T1 and T3 are the same, and the thickness T2 is about the same as the thicknesses T1 and T3. The thickness T2 may be slightly smaller than the thicknesses T1 and T3. This is because the shoulder knurled portion 80, which will be described later, can ensure a certain degree of strength in the base portion 37. For example, the thicknesses T1 and T3 are 0.6 mm, and the thickness T2 is 0.5 mm. It should be easily understood that these are not the only specific values. As mentioned above, injection molding and compression molding can be used when molding the cap 200, but in the case of a cap with a stepped structure, compression molding is generally unsuitable. However, as in this embodiment, by setting the wall thickness values ​​of the central apex 33, connecting portion 35, and base portion 37 of the top portion 31 to be the same or approximately the same, even in the case of compression molding, the flow of the softened thermoplastic resin (molding raw material) within the mold becomes smoother with respect to the stepped portion, thereby ensuring moldability.

[0030] On the lower surface of the base portion 37 of the top portion 31, an outer plug 50, a small projection 55, and an inner plug 70 are formed. The small projection 55 is formed at an intermediate position in the longitudinal direction of the base portion 37. The position of the inner plug 70 is closer to the connecting portion 35 than to the cylindrical portion 38 in the radial direction of the cap 200. Furthermore, the position of the inner plug 70 is offset from the extension line of the connecting portion 35. Here, the position of the inner plug 70 is radially outward from the connecting portion 35.

[0031] In other embodiments, as shown in Figure 5A, the inner plug 70 can also extend along the extending direction of the connecting portion 35 so as to be located on the extension line of the connecting portion 35. Alternatively, in terms of distance from the cylindrical portion 38, the inner plug 70 shown in Figure 5A is the same as the inner plug 70 shown in Figure 5, but the connecting portion 35 shown in Figure 5A is closer to the cylindrical portion 38 than the connecting portion 35 shown in Figure 5, and can be located on the extension line of the inner plug 70.

[0032] Here, the stepped structure of the cap 200 is useful for accommodating the shortened mouth 2 while maintaining the maximum height of the cap 200. Specifically, if the maximum height of the cap were to be lowered to accommodate the shortened mouth 2, this method would not be practical because it would require significant modifications to the beverage filling line (cap conveying line). In addition, it would become more difficult for users (consumers) to grip the cap and open and close it. In contrast, the stepped structure of the cap 200 allows the sealing point (small protrusion 55) for the mouth 2 to be lowered while maintaining the maximum height of the cap. Since the maximum height of the cap is maintained, it does not affect the beverage filling line and ensures that it is easy for users to open and close.

[0033] Next, the knurled structure of the cap 200 will be described with reference to Figures 3 and 6.

[0034] Multiple types (two types in this case) of knurling are formed on the outer circumferential surface of the cap body 30. Here, the multiple types of knurling consist of shoulder knurling sections 80 formed on the top section 31 and basic knurling sections 90 formed on the cylindrical section 38. Multiple shoulder knurling sections 80 are formed around the cap 200 at intervals from each other in the circumferential direction. Similarly, multiple basic knurling sections 90 are formed around the cap 200 at intervals from each other in the circumferential direction.

[0035] Multiple basic knurled sections 90 are formed at equal intervals in the circumferential direction of the cap 200. The number of basic knurled sections 90 is, for example, 30 or 60. The basic knurled sections 90 protrude radially outward from the outer circumferential surface of the cylindrical section 38. Alternatively, the space between adjacent basic knurled sections 90 is a recess (valley) on the outer circumferential surface of the cylindrical section 38.

[0036] The basic knurled section 90 extends parallel to the central axis YY of the cap 200, across the entire height of the cylindrical section 38. The lower end 91 of the basic knurled section 90 reaches the lower end of the cylindrical section 38 and connects to the maximum outer diameter section 45. On the other hand, the upper end 92 of the basic knurled section 90 reaches the upper end of the cylindrical section 38 and connects to the outer edge of the hem section 37. In addition, some of the multiple basic knurled sections 90 are connected to the shoulder knurled section 80.

[0037] Multiple shoulder knurled sections 80 are formed at equal intervals in the circumferential direction of the cap 200. In plan view, the multiple shoulder knurled sections 80 extend radially from the central axis YY of the cap 200. The number of shoulder knurled sections 80 is, for example, 30 or 60. The shoulder knurled sections 80 protrude radially outward from the outer circumferential surface of the top section 31. Alternatively, the space between adjacent shoulder knurled sections 80, 80 is a recess (valley) on the outer circumferential surface of the top section 31.

[0038] The shoulder knurled section 80 extends parallel to the central axis YY of the cap 200 and is connected to the outer surface of the connecting section 35 and the upper surface of the hem section 37. The shoulder knurled section 80 is also formed to connect the outer edge of the central apex 33 and the outer edge of the hem section 37, and the shape of the shoulder knurled section 80 is roughly fan-shaped when viewed from the front. That is, in the shoulder knurled section 80, of the two radii in the roughly fan-shaped section, one extends in the vertical direction and is connected to the connecting section 35, and the other extends in the horizontal direction and is connected to the hem section 37, and the center 81 of the circles of the two radii is connected to the connection point between the connecting section 35 and the hem section 37. In addition, in the shoulder knurled section 80, one end of the arc 82 in the fan shape is connected to the central apex 33, the other end is connected to the outer edge of the hem section 37, and then to the upper end 92 of the basic knurled section 90.

[0039] The relationship between the shoulder knurled section 80 and the basic knurled section 90 will be explained. The shoulder knurled section 80 and the basic knurled section 90 have the same wall thickness. The shoulder knurled section 80 has a greater radial outward projection length than the basic knurled section 90. The spacing between the shoulder knurled sections 80 is wider than the spacing between the basic knurled sections 90. In other words, the number of shoulder knurled sections 80 is less than the number of basic knurled sections 90. Here, the number of shoulder knurled sections 80 is half the number of basic knurled sections 90.

[0040] Furthermore, the shoulder knurled sections 80 are located at the same position in the circumferential direction as some of the basic knurled sections 90, and are connected to them. Here, the shoulder knurled section 80 is connected to one of the adjacent basic knurled sections 90. That is, the basic knurled sections 90 are located at the same position as the shoulder knurled sections 80 at alternating intervals in the circumferential direction and are connected to them. Therefore, the basic knurled sections 90 that reach the shoulder knurled sections 80 and those that do not are repeated alternately at equal intervals in the circumferential direction.

[0041] In other embodiments, two or more basic knurled sections 90 may be located between adjacent shoulder knurled sections 80, 80. Furthermore, the multiple shoulder knurled sections 80 do not all have to be evenly spaced in the circumferential direction. For example, a subset consisting of two or more shoulder knurled sections 80 may be treated as a single unit, and multiple subsets may be arranged at even intervals in the circumferential direction, with the area between adjacent subsets being a region without shoulder knurled sections 80. For example, for a total of 15 shoulder knurled sections 80, five subsets consisting of three shoulder knurled sections 80 may be formed, and each of the five subsets may be arranged like a line segment connecting the center and each vertex of a regular pentagon.

[0042] In other embodiments, the shoulder knurled portion 80 may not be connected to the central top portion 33. That is, the height of the shoulder knurled portion 80 may be reduced so that it is connected only to the outer surface of the connecting portion 35 and the upper surface of the hem portion 37. In yet another embodiment, the shoulder knurled portion 80 may not be connected to the central top portion 33 and the connecting portion 35, but only to the upper surface of the hem portion 37.

[0043] However, if ease of opening and closing the cap 200 by the user is a priority, then, as described above, it is better to have the height of the shoulder knurled section 80 be the same as the height of the central top section 33, and the width (horizontal length) of the shoulder knurled section 80 be the same as the length of the hem section 37, and to connect the shoulder knurled section 80 to the central top section 33, the connecting section 35, and the hem section 37.

[0044] Here, the greater the number of shoulder knurled sections 80 and basic knurled sections 90, the stronger the cap 200 becomes. On the other hand, increasing the number also increases the weight of the cap 200. From the perspective of balancing strength and weight, it is good to reduce the number of shoulder knurled sections 80, which are larger than the basic knurled sections 90, for example, by half the number of basic knurled sections 90 as described above.

[0045] Next, with reference to Figure 6, the weight-reducing structure of the cap 200 will be described.

[0046] At least some of the adjacent basic knurled sections 90, 90 have hollowed-out sections 100 formed between them. The hollowed-out sections 100 are portions that are carved out relative to the base surface (cylindrical surface) of the cylindrical section 38.

[0047] Multiple weight-reducing sections 100 are formed on the outer surface of the cylindrical section 38 at intervals from each other in the circumferential direction of the cap 200, and these intervals are uniform. Here, between adjacent basic knurled sections 90, 90, weight-reducing sections 100 and non-weight-reducing sections 110 alternate in the circumferential direction. The non-weight-reducing sections 110 are the parts that make up the base surface of the cylindrical section 38, and their cross-sectional shape is an arc centered on the central axis YY of the cap 200.

[0048] The weight-reducing section 100 extends parallel to the central axis YY of the cap 200, across the entire height of the cylindrical section 38. However, with respect to the length along the central axis YY, the height of the weight-reducing section 100 is shorter than the height of the basic knurled section 90. For example, the height of the weight-reducing section 100 is between 80% and 95% of the height of the basic knurled section 90. The upper end 102 of the weight-reducing section 100 is at the same level as the upper end 92 of the basic knurled section 90. On the other hand, the lower end 101 of the weight-reducing section 100 is located above the lower end 91 of the basic knurled section 90. That is, while the lower end 91 of the basic knurled section 90 reaches the maximum outer diameter section 45, the lower end 101 of the weight-reducing section 100 does not reach the maximum outer diameter section 45, and the boundary between the lower end 101 of the weight-reducing section 100 and the maximum outer diameter section 45 is part of the non-weight-reducing section 110. In this way, by separating the lower end 101 of the weight-reducing portion 100 from the maximum outer diameter portion 45, the reduction in strength of the cap 200 due to weight reduction can be suppressed. Regarding the length in the radial direction, the depth of the weight-reducing portion 100 is smaller than the dimensions (protruding length) of the basic knurled portion 90. For example, the depth of the weight-reducing portion 100 is 30% or more and 80% or less of the protruding length of the basic knurled portion 90.

[0049] The weight-reducing section 100 has a concave surface (curved surface) that is recessed inward, and this concave surface is recessed toward the central axis YY of the cap 200. Alternatively, the cross-sectional shape of the weight-reducing section 100 consists of a circular arc that curves inward toward the cap 200. The radius of curvature (R) of the circular arc shape of the weight-reducing section 100 is preferably in the range of 1.0 to 0.5 mm, and more preferably 0.72. If the R exceeds 1.0 mm, it is too large and the weight-reducing effect cannot be sufficiently obtained. The central part of the weight-reducing section 100 is the thinnest.

[0050] In other embodiments, the cutouts 100 may be formed at intervals of two or more, rather than every other basic knurled section 90, 90. Also, the cutouts 100 and non-cutout sections 110 may be formed in any order between adjacent basic knurled sections 90, 90 in the circumferential direction. For example, in the circumferential direction, the first cutout 100, the second cutout 100, and the non-cutout section 110 may be repeated in this order.

[0051] Here, although the weight of the cap 200 increases due to the knurled structure (especially the shoulder knurled section 80), it can be made lighter by the multiple cutouts 100. Furthermore, since this weight reduction does not affect the external dimensions of the cap (outer diameter of the cylindrical section 38, radial protrusion of the base knurled section 90), it can be made without or with minimal impact on various devices (e.g., cappers) in the beverage filling line that handle the cap 200.

[0052] Specifically, in a beverage filling line, for example, the jaws of the capper's chuck enter between the basic knurled sections 90, 90 of the cylindrical section 38 to hold the cylindrical section 38. There are multiple jaws in the chuck, and the cylindrical section 38 is held at multiple points in the circumferential direction and used for crimping. In the above-described embodiment, since the cylindrical section 38 of the cap 200 has a configuration in which the cut-out sections 100 and non-cut-out sections 110 are repeated in the circumferential direction, one of the jaws of the chuck can hold the cylindrical section 38 via the non-cut-out section 110. This minimizes the impact on the capper. If the capper in the beverage filling line is redesigned, it is also possible to change the configuration in which the cut-out sections 100 and non-cut-out sections 110 are repeated in the circumferential direction and adopt a configuration in which the non-cut-out sections 110 become cut-out sections 100. That is, depending on the embodiment of the capper, the cylindrical section 38 of the cap 200 may be configured so that all the spaces between adjacent basic knurled sections 90, 90 are cut-out sections 100.

[0053] Next, the shape of the inner plug 70 will be described in detail with reference to Figure 7.

[0054] The inner surface 79a of the inner plug 70 extends downward with a slight inclination radially outward. On the other hand, the outer surface 79b of the inner plug 70 generally extends downward with a slight inclination radially outward, then bends radially inward at the bending point 71, and then extends with a slight inclination radially inward. The inner surface 79a and the outer surface 79b of the inner plug 70 are radially connected by the lower end surface 72.

[0055] The outer surface 79b of the inner plug 70 has, from top to bottom, a base side surface 74 that extends slightly radially outward, a contact surface 73 at the bend 71, a guide surface 75, and a straight surface 76, with adjacent surfaces smoothly connected to each other. The contact surface 73 is located radially on the outermost part of the outer surface 79b of the inner plug 70. The contact surface 73 is the surface that contacts the inner surface of the mouth 2 when the plug is closed (see Figure 4). On the other hand, the guide surface 75 may contact the upper end of the mouth 2 during the closing process, but does not contact the inner surface of the mouth 2 when the plug is closed (see Figure 4).

[0056] The guide surface 75 is continuous with the lower side of the contact surface 73 and extends radially inward downward. The guide surface 75 is formed as an upwardly recessed concave curved surface. The concave curved surface can also be formed by connecting multiple arcs, but here it is formed by a single arc. The center of curvature 400 of the concave curved surface is located radially outward from the inner plug 70. The radius of curvature (R) of the concave curved surface is preferably in the range of 0.4 to 2.0 mm, and more preferably 1.5 mm. If it is less than 0.4 mm, it will match or come very close to the R of the inner surface of the bottle neck, increasing resistance and making crimping difficult, while if it is greater than 2.0 mm, it will not be effective.

[0057] The lower end portion 77 of the inner plug 70 extends below the guide surface 75. The lower end portion 77 includes the lower end surface 72 and the straight surface 76, and is shorter in length in the vertical direction than the guide surface 75. The lower end portion 77 is formed to be the thinnest part of the inner plug 70. In addition, a portion of the lower end portion 77, including the lower end surface 72, gradually becomes thicker towards the guide surface 75.

[0058] Next, we will explain the initial stages of shutting off the valve, referring to Figures 7-10.

[0059] Closing is performed not only when beverages or other liquids are filled into the container, but also when the user reseals the container. Closing is usually done by attaching (fitting) the cap 200 to the opening 2 and then rotating (screwing) the cap 200. Note that during closing, the attachment and rotation may be done in stages, or both may be done in parallel.

[0060] Figures 8 and 10 show a comparative example cap 300. The comparative example cap 300 differs from the embodiment cap 200 in terms of the shape of the lower part of the inner plug (particularly the guide surface). Specifically, the guide surface 75 of the inner plug 70 according to the embodiment is formed as a concave curved surface, whereas the guide surface 175 of the comparative example inner plug 170 is formed as a convex curved surface that protrudes downward. Since the guide surface 175 is oriented in the opposite direction to the guide surface 75, its center of curvature 500 is located inside the inner plug 170 in the radial direction. In addition, the lower end portion 177 of the comparative example inner plug 170 is shorter in the vertical direction compared to the lower end portion 77 of the inner plug 70 according to the embodiment, and does not include the straight surface 76.

[0061] Figures 7 and 8 show the initial stages of closing, where the inner plug 70 according to the embodiment and the inner plug 170 according to the comparative example first make contact with the upper part of the mouth 2. In the embodiment, the upper part of the guide surface 75 becomes the contact point with the mouth 2, whereas in the comparative example, the lower part of the guide surface 175 becomes the contact point with the mouth 2. This is due to the difference in the shapes of the guide surfaces 75 and 175.

[0062] Therefore, the vertical distance D1 between the contact surface 73 and the contact point in the embodiment is shorter than the vertical distance D2 between the contact surface 173 and the contact point in the comparative example. This means that, according to the embodiment, the timing at which the upper end of the opening 2 contacts the outer surface of the inner plug 70 can be delayed in the initial stage of closing. This also means that, according to the embodiment, the upper part of the opening 2 can be inserted further into the cap 200 in the initial stage of closing.

[0063] Figures 9 and 10 show the positions of the threaded portions 39 and 390 when the inner plug 70 according to the embodiment and the inner plug 170 according to the comparative example first make contact with the upper part of the opening 2, respectively, in the initial stage of closing. As described above, according to the embodiment, in the initial stage of closing, the opening 2 contacts the outer surface of the inner plug 70 later, so the opening 2 contacts the outer surface of the inner plug 70 at a stage where the screwing operation has progressed a little further than in the comparative example.

[0064] In other words, in the comparative example shown in Figure 10, the position 700 of the tip 390a of the threaded portion 390 relative to the threaded portion 16 is different from the position 600 of the tip 39a of the threaded portion 39 relative to the threaded portion 16 in the embodiment shown in Figure 9, where the threading is advanced (downward along the threaded portion 16). Therefore, according to the embodiment, misalignment of the threaded portions (angled cap overlap) can be suppressed more effectively than in the comparative example.

[0065] As described above, in the cap 200 according to this embodiment, the top portion 31 has a central apex portion 33, a base portion 37 whose outer edge is connected to the upper end of the cylindrical portion and which is located closer to the cylindrical portion 38 than the central apex portion 33, and a connecting portion 35 that connects the outer edge of the central apex portion 33 and the inner edge of the base portion 37, and the central apex portion 38, the base portion 37 and the connecting portion 35 are made of the same thickness.

[0066] According to this embodiment, since the cap 200 has a stepped shape overall in the top and cylindrical portions, a shape that corresponds to the reduction of container weight can be adopted (for example, a shape that lowers the sealing point without changing the height of the cap 200 by forming an inner plug 70 on the lower surface of the top portion 31). Furthermore, since the stepped portions, namely the central top portion 33, the base portion 37, and the connecting portion 35, are made of the same wall thickness, the softened molding material flows more smoothly within the mold during cap molding. This ensures moldability.

[0067] Furthermore, in this embodiment, the multiple shoulder knurled sections 80 and the multiple basic knurled sections 90 are made of the same thickness. This ensures moldability even for knurled structures that may have complex shapes in the cap 200.

[0068] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The elements, arrangement, materials, conditions, shapes, and sizes of the embodiments are not limited to those exemplified and can be modified as appropriate. Furthermore, it is possible to partially substitute or combine the configurations shown in different embodiments.

[0069] <Additional considerations regarding various embodiments>

[0070] [Embodiment 1] A cap having a cylindrical portion connected to the top, The aforementioned celestial part is, The central apex and, The outer edge is connected to the upper end of the cylindrical portion, and the base portion is located on the cylindrical portion side of the central top portion, It has a connecting portion that connects the outer edge of the central apex and the inner edge of the hem, The aforementioned central apex and connecting portion are made of the same thickness. The connecting portion is a cap having a thickness similar to or the same as that of the central top portion and the base portion.

[0071] [Embodiment 2] The cap according to Embodiment 1, wherein a plurality of shoulder knurled portions are formed, connected to the outer circumferential surface of the connecting portion and the upper surface of the hem portion, and protruding radially outward at intervals from each other in the circumferential direction.

[0072] [Embodiment 3] The cap according to embodiment 2, wherein the shoulder knurled portion is formed to connect the outer edge of the central apex and the outer edge of the hem.

[0073] [Embodiment 4] The cap according to embodiment 3, wherein the shape of the shoulder knurled portion is substantially fan-shaped.

[0074] [Embodiment 5] The cap according to any one of embodiments 2 to 4, wherein a plurality of basic knurled portions are formed on the outer circumferential surface of the cylindrical portion, projecting radially outward at intervals from each other in the circumferential direction.

[0075] [Embodiment 6] The cap according to Embodiment 5, wherein the shoulder knurled portion and the basic knurled portion are made of the same thickness.

[0076] [Embodiment 7] The cap according to embodiment 5 or 6, wherein the number of shoulder knurled sections is less than the number of basic knurled sections.

[0077] [Embodiment 8] The cap according to any one of embodiments 5 to 7, wherein the shoulder knurled portion has a greater radially outward protrusion length than the basic knurled portion.

[0078] [Embodiment 9] The cap according to any one of embodiments 5 to 8, wherein the shoulder knurled portion is located at the same position in the circumferential direction as some of the basic knurled portions and is connected to them.

[0079] [Embodiment 10] The cap according to embodiment 9, wherein the basic knurled portion consists of portions that reach the shoulder knurled portion and portions that do not reach the shoulder knurled portion, which are repeated alternately at equal intervals in the circumferential direction.

[0080] [Embodiment 11] The cap according to any one of embodiments 1 to 10, wherein an inner plug extending downward is formed on the lower surface of the hem portion.

[0081] [Embodiment 12] The cap according to embodiment 11, wherein the inner plug extends along the extending direction of the connecting portion so as to be located on the extension line of the connecting portion.

[0082] [Embodiment 13] The cap according to embodiment 11, wherein the inner plug is formed at a position offset from the extension line of the connecting portion.

[0083] [Embodiment 14] A cap according to any one of Embodiments 1 to 13, The container body with the aforementioned cap attached to its opening, A container equipped with [something]. [Explanation of Symbols]

[0084] 1...Bottle, 2...Mouth, 3...Shoulder, 4...Body, 5...Bottom, 6...Container body, 10...Circumferential wall, 12...Outer surface, 14...Inner surface, 18...Bead ring, 20...Support ring, 30...Cap body, 31...Top, 33...Center top, 35...Connecting part, 37...Bottom, 38...Cylinder, 39...Threaded part, 39a...Tip, 40...Tamper-evident band, 41...Bridge, 42...Nib, 45...Maximum outer diameter, 50...Outer plug, 55...Small protrusion, 70...Inner plug, 71...Bend, 72...Lower end surface, 73...Contact surface, 75...Guy D1, D2, YY, T1, T2, T3...Wall thickness

Claims

1. A resin cap having a cylindrical portion connected to the top, The aforementioned celestial part is, The central apex and, The outer edge is connected to the upper end of the cylindrical portion, and the base portion is located on the cylindrical portion side of the central top portion, It has a connecting portion that connects the outer edge of the central apex and the inner edge of the hem, The aforementioned central apex and hem are made of the same thickness. The connecting portion is a cap having a thickness similar to or the same as that of the central top portion and the base portion.

2. The cap according to claim 1, wherein a plurality of shoulder knurled portions are formed, connected to the outer circumferential surface of the connecting portion and the upper surface of the hem portion, and protruding radially outward at intervals from each other in the circumferential direction.

3. The cap according to claim 2, wherein the shoulder knurled portion is formed to connect the outer edge of the central apex and the outer edge of the hem.

4. The cap according to claim 3, wherein the shape of the shoulder knurled portion is substantially fan-shaped.

5. The cap according to claim 2, wherein a plurality of basic knurled portions are formed on the outer circumferential surface of the cylindrical portion, projecting radially outward at intervals from each other in the circumferential direction.

6. The cap according to claim 5, wherein the shoulder knurled portion and the basic knurled portion are made of the same thickness.

7. The cap according to claim 5, wherein the number of shoulder knurled sections is less than the number of basic knurled sections.

8. The cap according to claim 5, wherein the shoulder knurled portion has a greater radially outward protrusion length than the basic knurled portion.

9. The cap according to claim 5, wherein the shoulder knurled portion is located at the same position in the circumferential direction as some of the basic knurled portions and is connected to them.

10. The cap according to claim 9, wherein the basic knurled portion consists of portions that reach the shoulder knurled portion and portions that do not reach the shoulder knurled portion, which are repeated alternately at equal intervals in the circumferential direction.

11. The cap according to claim 1, wherein an inner plug extending downward is formed on the lower surface of the hem portion.

12. The cap according to claim 11, wherein the inner plug extends along the extending direction of the connecting portion so as to be located on the extension line of the connecting portion.

13. The cap according to claim 11, wherein the inner plug is formed at a position offset from the extension line of the connecting portion.

14. A cap according to any one of claims 1 to 13, The container body with the aforementioned cap attached to its opening, A container equipped with [something].

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