Cap and method for manufacturing cap

Abstract

To provide a cap capable of preventing a first seal surface of a pouring cylinder and a second seal surface of a lid from excessively adhering to each other due to the influence of heat in a closed state, and securing sealing performance between the pouring cylinder and the lid.SOLUTION: A cap 10 includes a cap body 17, a pouring cylinder 18 provided in the cap body 17, and a lid 19, in which the pouring cylinder 18 has a first seal surface 37 on an inner periphery, the lid 19 has a second seal surface 38 that comes into surface contact with the first seal surface 37 in a closed state, one of the first seal surface 37 and the second seal surface 38 has a surface roughness with an arithmetic mean height of 0.5 to 1.2 μ m, and the other seal surface has a surface roughness with an arithmetic mean height smaller than the arithmetic mean height of the one seal surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cap having a cap body and a lid, and a method for manufacturing the cap. [Background technology]

[0002] Conventionally, this type of cap has a cap body that is attached to a container, a dispensing tube provided on the cap body, and an upper lid that opens and closes the dispensing tube, as described in the following patent document.

[0003] The upper lid has a cylindrical sealing tube that fits into the tip of the dispensing tube in the closed state and detaches from the dispensing tube in the open state. In the closed state, the outer surface of the sealing tube tightly contacts the inner surface of the tip of the dispensing tube over the entire circumference, thereby sealing the upper lid and the dispensing tube. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-133970 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional type, in order to improve the sealing performance between the top lid and the pouring tube, it is conceivable to reduce the minute irregularities on the outer surface of the sealing tube and the inner surface of the tip of the pouring tube, thereby creating a smooth surface like a mirror finish.

[0006] However, when the outer peripheral surface of the sealed cylinder and the inner peripheral surface of the tip of the dispensing cylinder are made smooth as described above, for example, when a container is filled with a heat-sterilized liquid and then a closed cap is attached to the container, the heat of the heated liquid in the container causes excessive adhesion between the outer peripheral surface of the sealed cylinder and the inner peripheral surface of the tip of the dispensing cylinder, resulting in a problem of increased torque required to open the top lid.

[0007] Alternatively, when the container is a paper pack or the like, the cap body may be attached to the container by ultrasonic welding. In this case, the heat generated by ultrasonic welding causes excessive adhesion between the outer circumferential surface of the sealing cylinder and the inner circumferential surface of the tip of the dispensing cylinder, resulting in a problem of increased opening torque when opening the top lid.

[0008] The present invention aims to provide a cap and a method for manufacturing a cap that can prevent excessive adhesion between the first sealing surface of the pouring tube and the second sealing surface of the lid due to the influence of heat when the cap is closed, and that can ensure sealing performance between the pouring tube and the lid. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention provides a cap having a cap body attached to a container, a pouring tube provided in the cap body, and a lid for opening and closing the pouring tube, The dispensing barrel has a first sealing surface on the inner periphery or the outer periphery, the lid has a second seal surface that is in surface contact with the first seal surface over the entire periphery in a closed state; One of the first seal surface and the second seal surface has a surface roughness with an arithmetic mean height of 0.5 to 1.2 μm, The other of the first seal surface and the second seal surface is characterized by having a surface roughness whose arithmetic mean height is smaller than the arithmetic mean height of one of the seal surfaces.

[0010] According to this, in the closed state, the first seal surface of the pouring cylinder and the second seal surface of the lid are in surface contact over the entire circumference. At this time, the arithmetic mean height of one of the first seal surface and the second seal surface is 0.5 to 1.2 μm, and the arithmetic mean height of the other seal surface is smaller than the arithmetic mean height of the one seal surface, so that one seal surface is moderately rougher than the other seal surface.

[0011] This prevents the first and second sealing surfaces from coming into excessive contact with each other, even if the temperatures of the first and second sealing surfaces rise due to the influence of heat, and the tightness between the first and second sealing surfaces is not insufficient. This prevents an increase in opening torque when opening the lid of an unopened cap, and also ensures the sealing performance (sealing performance) between the lid and the dispensing tube when the lid is closed.

[0012] According to the cap of the present invention, the other of the first and second seal surfaces preferably has a surface roughness that is 0.5 to 0.9 times the arithmetic mean height of one of the seal surfaces.

[0013] According to the cap of the present invention, the cap body, the pouring barrel and the lid are preferably made of polyethylene or a synthetic resin containing polyethylene.

[0014] According to the cap of the present invention, the lid has a cylindrical sealing member that fits into the tip of the pouring cylinder in the closed state and that detaches from the pouring cylinder in the open state, The first sealing surface is formed on the inner periphery of the pouring cylinder, Preferably, the second sealing surface is formed on the outer periphery of the sealing member.

[0015] According to the cap of the present invention, the lid has a lid body and a holding member provided on the lid body, The lid body and the sealing member are separate bodies, The retaining member preferably retains the sealing member.

[0016] The present invention provides a method for manufacturing the cap according to any one of the above-mentioned inventions by injection molding, comprising the steps of: roughening the surface of the mold in a portion where one of the first and second sealing surfaces of the cap is formed, so that the arithmetic mean height of the surface of the mold in this portion is 0.5 to 1.2 μm; The method is characterized in that one of the sealing surfaces is molded by injecting molten resin into a mold, thereby making the arithmetic mean height of the one of the sealing surfaces 0.5 to 1.2 μm.

[0017] As a result, by injection molding a cap, it is possible to manufacture a cap in which the arithmetic mean height of one of the first and second seal surfaces is 0.5 to 1.2 μm, and the arithmetic mean height of the other seal surface is smaller than the arithmetic mean height of one of the seal surfaces.

[0018] According to the method for manufacturing a cap of the present invention, the roughening treatment is a blast treatment. This allows the surface of the mold in the area where one of the sealing surfaces is formed to be easily processed so that the arithmetic mean height is 0.5 to 1.2 μm. [Effects of the Invention]

[0019] As described above, according to the present invention, in the closed state, it is possible to prevent the first sealing surface of the dispensing tube and the second sealing surface of the lid from coming into excessive contact with each other due to the influence of heat, and it is also possible to ensure the sealing performance between the lid and the dispensing tube. This prevents an increase in opening torque when opening the lid, and prevents liquid in the container from leaking out from between the lid and the dispensing tube when the lid is closed. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a cap according to a first embodiment of the present invention, showing an unopened state. [Figure 2] FIG. 2 is a cross-sectional view of the cap in an opened state. [Figure 3] 10 is a graph showing the relationship between the storage period when the cap is stored at a temperature of 30° C. and the opening torque of the cap after storage. [Figure 4] 10 is a graph showing the relationship between the storage period when the cap is stored at a temperature of 5° C. and the opening torque of the cap after storage. [Figure 5]FIG. 10 is a cross-sectional view of the cap according to the second embodiment, showing the cap in an unopened state. [Figure 6] FIG. 2 is a cross-sectional view of the cap in an opened state. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. (First embodiment)

[0022] In the first embodiment, as shown in Figures 1 and 2, a screw-type cap 10 is provided on the top of a container 1 such as a paper pack. The container 1 contains a liquid content (not shown), such as a beverage such as alcohol or milk, or a seasoning such as soy sauce or oil.

[0023] The direction of the axis 11 passing through the center of the cap 10 is defined as the vertical direction 12, the direction perpendicular to the axis 11 is defined as the radial direction 13, and the circumferential direction centered on the axis 11 is defined as the circumferential direction (not shown). The cap 10 has a cap body 17 attached to the container 1, a cylindrical dispensing tube 18 provided on the cap body 17, and a lid 19 for opening and closing the dispensing tube 18.

[0024] The cap body 17 has a plate-shaped mounting member 21 that is welded to the container 1 by ultrasonic welding. The dispensing tube 18 is provided upright on the mounting member 21. A male screw 22 is formed on the outer periphery of the dispensing tube 18.

[0025] A detachment member 23 that can be detached from the inside of the dispensing tube 18 is provided inside the dispensing tube 18. The detachment member 23 has a detachment part main body 25 surrounded by a breakable thin-walled weakened part 24, a support pillar 26 erected on the detachment part main body 25, and a pull ring 27 provided at the tip of the support pillar 26.

[0026] As shown in Figure 2, the lid 19 is removed from the cap body 17, and the pull ring 27 is pulled to break the weakened portion 24, whereby the detachment member 23 is detached from inside the dispensing tube 18 as shown by the imaginary line in Figure 2, and a through hole (not shown) that opens between the inside of the container 1 and the tip of the dispensing tube 18 is formed inside the dispensing tube 18.

[0027] The lid 19 has a disk-shaped lid plate 31, a cylindrical peripheral wall portion 32 extending downward from the outer periphery of the lid plate 31, and a cylindrical sealing member 33 provided on the inside of the peripheral wall portion 32. An internal thread 35 that can be threaded onto the external thread 22 is formed on the inner periphery of the peripheral wall portion 32. The sealing member 33 extends downward from the inner surface of the lid plate 31, and as shown in Figure 1, fits into the tip of the dispensing tube 18 in the closed state, and as shown in Figure 2, it detaches from the dispensing tube 18 in the open state.

[0028] A first seal surface 37 is formed around the entire inner circumference of the tip of the dispensing tube 18. The lid 19 has a second seal surface 38 that comes into surface contact with the first seal surface 37 around the entire circumference when the cap is closed. The second seal surface 38 (an example of one of the seal surfaces) is formed around the entire outer circumference of the seal member 33, and has a surface roughness such that the arithmetic mean height (Sa) specified in JIS B0601 is 0.5 to 1.2 μm. The first seal surface 37 (an example of the other seal surface) has a surface roughness that is 0.5 to 0.9 times the arithmetic mean height of the second seal surface . For example, if the arithmetic mean height of the second seal surface 38 is 1.0 μm, the arithmetic mean height of the first seal surface 37 is set within the range of 0.5 to 0.9 μm.

[0029] 1, in the cap 10 in a closed state with the lid 19 closed, the contact width W between the first sealing surface 37 and the second sealing surface 38 is preferably 1 mm or more. The cap body 17, the dispensing tube 18, and the lid 19 are made of polyethylene. The operation of the above configuration will now be described.

[0030] The attachment member 21 of the cap body 17 is welded to the container 1 by ultrasonic welding, with the lid 19 attached to the dispensing tube 18. In this way, the unopened cap 10 is attached to the container 1.

[0031] 1, in the closed state, the first seal surface 37 of the pouring tube 18 and the second seal surface 38 of the lid 19 are in surface contact over the entire circumference. At this time, the arithmetic mean height of the second seal surface 38 is 0.5 to 1.2 μm, and the arithmetic mean height of the first seal surface 37 is 0.5 to 0.9 times the arithmetic mean height of the second seal surface 38, so the second seal surface 38 is appropriately rougher than the first seal surface 37.

[0032] This prevents the first seal surface 37 and the second seal surface 38 from coming into excessive contact with each other even if the temperatures of the first seal surface 37 and the second seal surface 38 rise due to the heat generated by ultrasonic welding, and prevents the first seal surface 37 and the second seal surface 38 from coming into insufficient contact with each other.

[0033] Therefore, as shown in Fig. 2, when the lid 19 of the unopened cap 10 is turned in the open direction to open it, it is possible to prevent an increase in the opening torque (the torque required to open the lid 19 from a closed state). Also, it is possible to ensure the sealing performance (sealing performance) between the lid 19 and the dispensing tube 18 when the lid 19 is turned in the closing direction to close it.

[0034] Graphs G1 and G2 in Figure 3 and graphs G3 and G4 in Figure 4 each show the relationship between the storage period when an unopened cap 10 is stored at a specified temperature and the opening torque required to turn the lid 19 of the unopened cap 10 in the opening direction to open it after storage.

[0035] Graph G1 in Figure 3 and graph G3 in Figure 4 each show the cap 10 of the present invention, in which the arithmetic mean height of the second seal surface 38 is 0.5 to 1.2 μm, and the arithmetic mean height of the first seal surface 37 is 0.5 to 0.9 times the arithmetic mean height of the second seal surface 38.

[0036] Graph G2 in FIG. 3 and graph G4 in FIG. 4 each show the cap of Reference Example A, with the arithmetic mean height of first seal surface 37 and second seal surface 38 both set to 0.2 μm.

[0037] Graphs G1 and G2 in Figure 3 are based on data obtained by storing the cap 10 in a finished state, with the lid 19 attached (set) to the dispensing tube 18, in an incubator at a temperature of 30°C, removing it from the incubator after a specified storage period, immediately ultrasonically welding it to the container 1 in a room temperature environment, and then aging it for one hour in a 23°C environment, after which the opening torque was measured, with the horizontal axis representing the storage period and the vertical axis representing the opening torque.

[0038] Furthermore, graphs G3 and G4 in Figure 4 are based on data obtained by storing the cap 10 in a finished state with the lid 19 attached (set) to the dispensing tube 18 in an incubator at a temperature of 5°C, removing it from the incubator after a specified storage period, immediately ultrasonically welding it to the container 1 in a room temperature environment, and then aging it for one hour in a 23°C environment, after which the opening torque was measured, with the horizontal axis representing the storage period and the vertical axis representing the opening torque.

[0039] 3, it can be seen that the opening torque of the cap 10 of the present invention (graph G1) is lower than that of the cap of Reference Example A (graph G2). This is because the cap 10 of the present invention has many fine irregularities formed on the second seal surface 38, which prevents the first seal surface 37 and the second seal surface 38 from coming into excessive contact with each other.

[0040] In contrast, in the cap of Reference Example A, the second seal surface 38 has few minute irregularities, and the first seal surface 37 and the second seal surface 38 are in excessively close contact with each other, resulting in an increased opening torque. Similarly, it can be seen from graphs G3 and G4 in FIG. 4 that the opening torque of the cap 10 of the present invention is lower than that of the cap of Reference Example A. Table 1 below shows data on the sealing performance (sealing ability) of the cap 10 of the present invention and the cap of Reference Example B. [Table 1]

[0041] In Table 1 above, as shown by the solid line in Figure 2, the lid 19 of an unopened cap 10 attached to container 1 was rotated in the opening direction to remove it from the dispensing tube 18. As shown by the imaginary line in Figure 2, the pull ring 27 was pulled to remove the release member 23 to open the cap 10, and then the lid 19 was rotated in the closing direction with a predetermined torque (19.6 [N·cm]) to attach it to the dispensing tube 18 and close the cap 10. Then, the container 1 was turned upside down with the cap 10 facing downward and held upside down for four hours. After that, the container 1 was returned to its original position with the cap 10 facing upward, and the lid 19 was rotated in the opening direction to remove it from the dispensing tube 18. Table 1 shows the results of a visual inspection to determine whether the liquid content of container 1 (a mixture of 65% water and 35% ethanol) had leaked out from between the dispensing tube 18 and the sealing member 33.

[0042] In the caps 10 of the present invention, the average value of the arithmetic mean height of the second seal surface 38 of ten caps 10 is 1.1 μm. In addition, in the caps of Reference Example B, the average value of the arithmetic mean height of the second seal surface 38 of ten caps 10 is 1.3 μm. According to this, in the cap of Reference Example B, leakage of the content liquid from between the dispensing tube 18 and the seal member 33 occurred in two of the ten caps 10.

[0043] In contrast, in the caps 10 of the present invention, no leakage of the content liquid from between the dispensing tube 18 and the seal member 33 was confirmed in any of the ten caps 10. As a result, in the cap 10 of the present invention, there was no insufficient tightness between the first seal surface 37 and the second seal surface 38, and the sealing performance between the lid 19 and the dispensing tube 18 when the lid 19 was closed was ensured.

[0044] Next, a manufacturing method for manufacturing the cap 10 by injection molding will be described. The cap body 17 of the cap 10 is injection molded using a first mold, and the lid 19 is injection molded using a second mold. In the first mold, the mold surface of the portion where the first sealing surface 37 of the pouring tube 18 of the cap body 17 is molded is polished. In the second mold, the mold surface of the portion where the second sealing surface 38 of the lid 19 is molded is blasted (an example of roughening) to give the mold surface in this portion a surface roughness of 0.5 to 1.2 μm in arithmetic mean height.

[0045] Thereafter, the second mold is closed, and molten polyethylene is injected into the interior of the second mold and cooled to form the lid 19. Thereafter, the second mold is opened, and the lid 19 is removed from the second mold.

[0046] In this case, a large number of fine irregularities are formed on the mold surface by blasting rather than polishing, and the fine irregularities on the blasted mold surface are transferred to the second sealing surface 38 of the lid 19. As a result, the arithmetic mean height of the second sealing surface 38 becomes 0.5 to 1.2 μm.

[0047] The first mold, which has not been blasted, is then closed, and molten polyethylene is poured into the first mold and cooled to form the cap body 17. The first mold is then opened, and the cap body 17 is removed from the first mold. As a result, the arithmetic mean height of the first seal surface 37 of the dispensing tube 18 of the cap body 17 becomes 0.5 to 0.9 times the arithmetic mean height of the second seal surface 38 due to the polishing of the mold surface.

[0048] In the first embodiment, the seal member 33 fits inside the tip of the dispensing tube 18 in the closed state as shown in Fig. 1, but it may also fit onto the outer periphery of the tip of the dispensing tube 18 in the closed state. In this case, the first seal surface 37 is formed on the outer periphery of the tip of the dispensing tube 18, and the second seal surface 38 is formed on the inner periphery of the seal member 33.

[0049] In the first embodiment, the cap body 17, the dispensing tube 18, and the lid 19 are made of polyethylene, but they may be made of synthetic resin containing polyethylene at a predetermined ratio.

[0050] In the first embodiment described above, the arithmetic mean height of second seal surface 38 is set to 0.5 to 1.2 μm, and the arithmetic mean height of first seal surface 37 is set to 0.5 to 0.9 times the arithmetic mean height of second seal surface 38. However, the arithmetic mean height of first seal surface 37 may be set to 0.5 to 1.2 μm, and the arithmetic mean height of second seal surface 38 may be set to 0.5 to 0.9 times the arithmetic mean height of first seal surface 37. In this case, the arithmetic mean height of the mold surface in the portion where first seal surface 37 is molded may be processed to 0.5 to 1.2 μm, and similar actions and effects can be obtained.

[0051] In the first embodiment, the container 1 is provided with a screw-type cap 10 as shown in FIG. 1, but a hinge-type cap 60 as described in the second embodiment below may also be provided.

[0052] (Second embodiment) The second embodiment will be described below. Note that the same members as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0053] As shown in Figures 5 and 6, the cap 60 has a cap body 64 that is attached to the mouth 62 of a container 61 such as a PET bottle, a cylindrical dispensing tube 65 provided on the cap body 64, and a lid 66 that opens and closes the dispensing tube 65.

[0054] The cap body 64 has a cylindrical inner tube member 68 that is fitted inside the mouth portion 62 of the container 61, a cylindrical outer tube member 69 that is fitted outside the mouth portion 62, and a circular partition wall 70 provided inside the lower end portion of the inner tube member 68.

[0055] A groove 72 that is closed at the top and open at the bottom is formed around the entire circumference between the inner cylindrical member 68 and the outer cylindrical member 69. The cap body 64 is attached to the mouth 62 of the container 61 by inserting the mouth 62 of the container 61 into the groove 72. The dispensing tube 65 is provided on the partition wall 70, facing upward. The lid 66 is connected to the cap body 64 via a hinge 73 so as to be rotatable in opening and closing directions 74 and 75 . The lid 66 has a lid main body 78 , a cylindrical holding member 79 provided on the lid main body 78 , and an inner plug 80 held inside the holding member 79 .

[0056] The lid body 78 has a disk-shaped lid plate 82, a cylindrical outer peripheral wall portion 83 extending downward from the outer periphery of the lid plate 82, and a cylindrical inner peripheral wall portion 84 provided inside the outer peripheral wall portion 83.

[0057] The retaining member 79 is provided inside the inner peripheral wall portion 84 and extends downward from the cover plate 82. The cover body 78 and the inner plug 80 are separate bodies. The inner plug 80 has a cylindrical sealing member 86, a circular top plate portion 87 provided at the upper end of the sealing member 86, and an annular locking piece 88 bent downward from the outer periphery of the top plate portion 87.

[0058] A circular recess 89 that is open downward is formed between the sealing member 86 and the locking piece 88 in the radial direction 13. In addition, a protrusion 91 is formed on the inner periphery of the lower end of the holding member 79 to prevent the inner plug 80 from falling out from inside the holding member 79.

[0059] 5, in the closed state, the seal member 86 of the inner plug 80 fits into the tip of the dispensing tube 65, and the tip of the dispensing tube 65 fits into the recess 89 of the inner plug 80. In addition, as shown in FIG. 6, in the open state, the seal member 86 of the inner plug 80 detaches from the tip of the dispensing tube 65, and the tip of the dispensing tube 65 detaches from the recess 89 of the inner plug 80.

[0060] A first seal surface 37 (an example of one of the seal surfaces) is formed around the entire inner periphery of the tip of the dispensing tube 65. The first seal surface 37 has a surface roughness of 0.5 to 1.2 μm in arithmetic mean height (Sa) as specified in JIS B0601.

[0061] The lid 66 has a second seal surface 38 (an example of the other seal surface) that is in surface contact with the first seal surface 37 over the entire circumference when the lid 66 is closed. The second seal surface 38 is formed over the entire circumference of the seal member 86 of the inner plug 80, and has a surface roughness that is 0.5 to 0.9 times the arithmetic mean height of the first seal surface 37. The cap body 64, the dispensing tube 65, the lid 66 and the inner plug 80 are made of polyethylene. The operation of the above configuration will now be described.

[0062] After producing the cap 60, the lid 66 is closed to form a stoppered state. Then, the container 61 is filled with a heat-sterilized liquid content (not shown), and the cap 60 is attached to the container 61, whereby the opening 62 of the container 61 is inserted into the groove 72, and the unopened cap 60 is attached to the container 61, as shown in FIG.

[0063] In the closed state, the first seal surface 37 of the pouring cylinder 65 and the second seal surface 38 of the lid 66 are in surface contact over the entire circumference. At this time, the arithmetic mean height of the first seal surface 37 is 0.5 to 1.2 μm, and the arithmetic mean height of the second seal surface 38 is 0.5 to 0.9 times the arithmetic mean height of the first seal surface 37, so the first seal surface 37 is appropriately rougher than the second seal surface 38.

[0064] This prevents the first sealing surface 37 and the second sealing surface 38 from coming into excessive contact with each other even if the temperature of the first sealing surface 37 and the second sealing surface 38 rises due to the influence of the heat of the heated liquid contents in the container 61, and prevents the first sealing surface 37 and the second sealing surface 38 from coming into insufficient contact with each other.

[0065] Therefore, as shown in Fig. 6, it is possible to prevent an increase in opening torque when opening the lid 66 of the unopened cap 60. Furthermore, as shown in Fig. 5, it is possible to ensure the sealing performance (sealing performance) between the inner plug 80 and the dispensing tube 18 when the lid 66 is closed.

[0066] Next, a manufacturing method for manufacturing the cap 60 by injection molding will be described. The cap 60 other than the inner plug 80 is injection molded using a first mold, and the inner plug 80 is injection molded using a second mold.

[0067] Of these, in the first mold, the mold surface of the portion where the first seal surface 37 of the dispensing tube 18 is molded is subjected to blasting (an example of roughening) to provide a surface roughness of 0.5 to 1.2 μm in arithmetic mean height of the mold surface in this portion. Also, in the second mold, the mold surface of the portion where the second seal surface 38 of the seal member 86 of the inner plug 80 is molded is polished.

[0068] Thereafter, the first mold is closed, and molten polyethylene is injected into the first mold and cooled to form the cap 60 except for the inner plug 80. Thereafter, the first mold is opened, and the cap 60 except for the inner plug 80 is removed from the first mold.

[0069] According to this, since a large number of fine irregularities are formed on the surface of the mold by the blasting process, the fine irregularities on the mold surface that have been subjected to the blasting process, rather than polishing, are transferred to the first seal surface 37 of the dispensing tube 18. As a result, the arithmetic mean height of the first seal surface 37 becomes 0.5 to 1.2 μm.

[0070] The second mold, which has not been blasted, is then closed, and molten polyethylene is poured into the second mold and cooled to form the inner plug 80. The second mold is then opened, and the inner plug 80 is removed from the second mold. As a result, the arithmetic mean height of the second seal surface 38 of the seal member 86 of the inner plug 80 becomes 0.5 to 0.9 times the arithmetic mean height of the first seal surface 37 due to the polishing of the mold surface. Thereafter, the inner plug 80 is fitted into the inside of the holding member 79, thereby producing the cap 60 as shown in FIG.

[0071] In the second embodiment, the seal member 86 of the inner plug 80 fits inside the tip of the dispensing cylinder 65 in the closed state as shown in Fig. 5, but it may also fit onto the outer periphery of the tip of the dispensing cylinder 65 in the closed state. In this case, the first seal surface 37 is formed on the outer periphery of the tip of the dispensing cylinder 65, and the second seal surface 38 is formed on the inner periphery of the seal member 86.

[0072] In the second embodiment, the cap body 64, the dispensing tube 65, the lid 66, and the inner plug 80 are made of polyethylene, but they may also be made of synthetic resin containing polyethylene at a predetermined ratio.

[0073] In the second embodiment described above, the arithmetic mean height of first seal surface 37 is set to 0.5 to 1.2 μm, and the arithmetic mean height of second seal surface 38 is set to 0.5 to 0.9 times the arithmetic mean height of first seal surface 37. However, the arithmetic mean height of second seal surface 38 may be set to 0.5 to 1.2 μm, and the arithmetic mean height of first seal surface 37 may be set to 0.5 to 0.9 times the arithmetic mean height of second seal surface 38. In this case, the arithmetic mean height of the mold surface in the portion where second seal surface 38 is molded may be processed to 0.5 to 1.2 μm, and similar actions and effects can be obtained.

[0074] In the first embodiment described above, the mold surface in the portion where the second seal surface 38 is molded is blasted to achieve a surface roughness such that the arithmetic mean height of the mold surface in this portion is 0.5 to 1.2 μm, and in the second embodiment described above, the mold surface in the portion where the first seal surface 37 is molded is blasted to achieve a surface roughness such that the arithmetic mean height of the mold surface in this portion is 0.5 to 1.2 μm, but this is not limited to blasting, and a embossing process other than blasting may also be used. [Explanation of symbols]

[0075] 1 container 10 Caps 17 Cap body 18 Pour tube 19 Lid 33 Sealing material 37 First seal surface 38 Second sealing surface 60 Cap 61 Container 64 Cap body 65 Pour tube 66 Lid 78 Lid body 79 Retaining member 86 Sealing material

Claims

1. A cap having a cap body attached to a container, a pouring tube provided in the cap body, and a lid for opening and closing the pouring tube, The dispensing barrel has a first sealing surface on an inner periphery or an outer periphery, the lid has a second sealing surface that is in surface contact with the first sealing surface over the entire periphery in a closed state; one of the first seal surface and the second seal surface has a surface roughness having an arithmetic mean height of 0.5 to 1.2 μm; A cap characterized in that the other of the first seal surface and the second seal surface has a surface roughness whose arithmetic mean height is smaller than the arithmetic mean height of one of the seal surfaces.

2. The cap described in claim 1, characterized in that the other of the first seal surface and the second seal surface has a surface roughness that is 0.5 to 0.9 times the arithmetic mean height of one of the seal surfaces.

3. 2. The cap according to claim 1, wherein the cap body, the dispensing tube and the lid are made of polyethylene or a synthetic resin containing polyethylene.

4. The lid has a cylindrical sealing member that fits into the tip of the dispensing cylinder in a closed state and that detaches from the dispensing cylinder in an open state; The first sealing surface is formed on the inner periphery of the pouring barrel, 2. The cap of claim 1, wherein the second sealing surface is formed on an outer periphery of the sealing member.

5. The lid has a lid body and a holding member provided on the lid body, The lid body and the sealing member are separate bodies, 5. The cap according to claim 4, wherein the retaining member retains the sealing member.

6. A manufacturing method for manufacturing the cap according to any one of claims 1 to 5 by injection molding, comprising: a surface of the mold in a portion where one of the first seal surface and the second seal surface of the cap is molded is roughened to have a surface roughness such that the arithmetic mean height of the surface of the mold in this portion is 0.5 to 1.2 μm; A method for manufacturing a cap, comprising injecting molten resin into a mold to form one of the sealing surfaces, so that the arithmetic mean height of the one of the sealing surfaces is set to 0.5 to 1.2 μm.

7. 7. The method for manufacturing a cap according to claim 6, wherein the surface roughening is a blasting process.

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