JP6934804B2 - Cap with liner and its manufacturing method - Google Patents

Description

The present invention relates to a cap with a liner for sealing a container for beverages and the like, and a method for producing the same.

As a cap to be attached to a container made of steel, an aluminum alloy, or the like, a cap having a metal cap main body and a liner provided on the inner surface of the top plate portion of the cap main body is known. When the container is closed by the cap, the liner comes into contact with the top of the mouth of the container, so that the inside of the container can be sealed.

Conventionally, a cap having such a liner (a cap with a liner) has a predetermined shape by dropping a molten resin ball onto the inner surface of the top plate of the cap body and embossing it with a molding die. In-shell mold type metal caps that form liners are known.

For example, in Patent Document 1, a predetermined amount of molten soft synthetic resin material is supplied into a cap (metal cap), and the synthetic resin material is pressed by a liner forming jig to form a synthetic resin liner. It is described that the cap is formed in a state of being adhered to the inner surface of the top plate portion of the cap. Further, in Patent Document 1, in such a molding method, a lacking portion (incompletely molded portion) is formed in the synthetic resin liner by molding the molten synthetic resin material in a biased manner in the cap. It is described that there is a risk and that the sealing property of the container may be deteriorated due to the lacking portion of the synthetic resin liner. In Patent Document 1, it is presumed that air is mixed between the liner forming jig and the synthetic resin liner as the cause of the formation of the missing portion, and the surface roughness of the liner forming jig is set to a predetermined value. It is described that by setting the above and making it coarse, the air between the liner forming jig and the synthetic resin liner is uniformly dispersed to make the flow of the synthetic resin material uniform and prevent the formation of the missing portion. Has been done. According to Patent Document 1, the surface roughness Ra (according to JIS B 0601) of the synthetic resin liner is preferably 0.1 μm or more, preferably 5.0 μm or less, and the surface roughness Ry (JIS). B 0601) is preferably 0.1 μm or more, and preferably 50.0 μm or less.

Japanese Unexamined Patent Publication No. 2003-200959

However, as described in Patent Document 1, when the surface roughness of the liner forming jig is roughened, it is assumed that the air between the liner forming jig and the synthetic resin liner can be uniformly dispersed. However, the air in the molding space cannot be smoothly released to the outside, and an air pool is likely to be formed in the peripheral portion. For this reason, the fluidity of the synthetic resin material is hindered at that portion, so that a missing portion (incompletely molded portion) may be formed on the synthetic resin liner. Further, even if the surface roughness of the liner forming jig is roughly formed, the air between the liner and the top plate of the metal cap cannot be uniformly dispersed on the opposite surface side of the synthetic resin liner, and the liner is synthesized. Air pools are likely to form between the resin liner and the metal cap. Therefore, there is a possibility that a missing portion may be formed without filling the portion with the resin. Further, when a missing portion is formed on the back surface side of the synthetic resin liner (the contact surface side with the top plate portion of the metal cap) in this way, the missing portion is the back surface side of the synthetic resin liner. It is difficult to find the missing part by inspection because it hides in the plastic.

Further, as described in Patent Document 1, when the surface roughness of the surface side (contact surface side with the liner forming jig) of the synthetic resin liner is roughened, the surface area of the synthetic resin liner becomes too large. As a result, useful components (for example, fragrances) in the contents (beverage) inside the container may be adsorbed to deteriorate the flavor property, or the contents themselves may adhere to cause dripping.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a cap with a liner capable of preventing the formation of a missing portion of a liner and improving the sealing property of a container, and a method for manufacturing the same.

The cap with a liner of the present invention is a cap that is attached to the mouth of a container and can seal the mouth, and has a top plate and a cylindrical portion substantially hung from the peripheral edge of the top plate. A main body and a liner provided on the inner surface of the top plate portion are provided, and the liner is arranged on the inner surface side of the top plate portion and slides on the top plate portion, and the sliding layer. The sliding layer is provided with a sealing layer which is softer than the sliding layer and has a smaller outer diameter and is in contact with the container. Is more than 20.0 μm and 40.0 μm or less .

The surface roughness Rz is determined by the maximum height conforming to JIS B 0601: 2001 in the JIS standard (Japanese Industrial Standards).
In the cap with a liner configured as described above, the sealing layer of the liner supplies the molten resin onto the first surface of the sliding layer in the cap body, and the molten resin is used as a mold (punch) for forming the sealing layer. It is formed (molded) by molding. The sliding layer may be formed by punching a hard sheet into a disk shape in advance and placed in the cap body, or may be formed in the cap body, that is, on the inner surface of the top plate portion, like the sealing layer. The molten resin may be supplied and pressed by a mold for molding a sliding layer to be formed by molding.

The mold for forming the sealing layer is, for example, a sleeve punch that contacts the first surface of the sliding layer to define the outer diameter of the sealing layer, and a sealing layer that is arranged at a distance from the first surface of the sliding layer. It is equipped with a center punch that defines the thickness of the. In the sealing layer, after supplying the molten resin onto the first surface of the sliding layer, the molten resin is pressed by a cooled mold for forming the sealing layer, and the first surface of the sliding layer and the inside of the sleeve punch are pressed. It is formed by filling the internal space surrounded by the peripheral surface and the pressing surface of the center punch.

In the process of forming such a sealing layer, the molten resin supplied on the first surface of the sliding layer has a surface roughness (maximum height) Rz of the first surface of 5.0 μm or more and 50.0 μm or less in advance. Immediately after supply, it is supported by the convex portion without entering the concave portion of the unevenness on the first surface.

Next, the mold for forming the sealing layer is pressed against the molten resin to bring the sleeve punch into contact with the first surface, and the surface roughness Rz of the first surface of the sliding layer is provided at 5.0 μm or more and 50.0 μm or less. Therefore, a gap is maintained between the sleeve punch and the sliding layer so that air can move between the internal space of the mold for forming the sealing layer and the outside. Therefore, the air in the internal space is smoothly discharged to the outside from between the sleeve punch and the sliding layer, that is, from the peripheral edge of the internal space. Further, since the first surface is formed with irregularities having a predetermined surface roughness Rz, the resistance between the convex portion of the first surface and the molten resin is maintained small, and the molten resin is radially inside. It can be smoothly and radially flowed from the outside to the outside. Therefore, the molten resin can be smoothly filled up to the peripheral edge of the internal space, and it is possible to prevent the peripheral portion of the sealing layer from being deficient.

Further, in the latter stage of molding the molten resin by the mold for forming the sealing layer, the molten resin is pressed toward the first surface of the sliding layer by the mold for forming the sealing layer, so that the molten resin and the sliding layer are melted. The air intervening between the resin and the resin is finally discharged to the outside from the peripheral edge of the internal space through the recess on the first surface. Therefore, the molten resin penetrates deeply into the unevenness of the first surface, and the molten resin is cured in this state, so that the adhesive strength between the sliding layer and the sealing layer can be maintained high.

As described above, in the cap with liner of the present invention, the surface roughness Rz of the first surface of the sliding layer is formed to be 5.0 μm or more and 50.0 μm or less. Can be prevented from being formed, and the yield of the liner can be increased. Therefore, the tightness of the container can be improved.

When the surface roughness Rz of the first surface of the sliding layer is less than 5.0 μm, air is smoothly flowed from the peripheral edge of the internal space of the mold for molding the sealing layer to the outside when molding the sealing layer. It becomes difficult to discharge. Further, if the surface roughness Rz of the first surface exceeds 50.0 μm, the molten resin tends to leak from the peripheral edge portion of the internal space to the outside, and there is a possibility that a deficiency portion is formed in the sealing layer. The optimum range of the surface roughness Rz of the first surface is 20.0 μm or more and 40.0 μm or less.

In a preferred embodiment of the cap with a liner of the present invention, the hardness of the sliding layer is preferably 70 or more and 85 or less in terms of type D durometer hardness.

According to JIS K 7215 in JIS standard (Japanese Industrial Standards), if the type D durometer hardness measured by type D is 70 or more, even when the mold for sealing layer molding is pressed against the sliding layer. , The uneven shape of the first surface can be maintained, and air can be smoothly discharged from between the mold and the sliding layer. Therefore, it is possible to surely prevent the formation of the missing portion of the sealing layer.
If the hardness of the type D durometer is less than 70, when the mold is pressed against the sliding layer, the unevenness of the first surface may be crushed at the contact portion and air bleeding may be hindered. On the other hand, when the hardness of the type D durometer exceeds 85, the hardness of the sliding layer becomes high, so that the liner is less likely to be deformed. Therefore, when the cap with a liner is attached to the mouth of the container, the liner is less likely to be deformed along the shape of the mouth, and the adhesion between the sealing layer and the mouth may be impaired.

In a preferred embodiment of the cap with a liner of the present invention, the thickness of the sliding layer is preferably 0.30 mm or more and 0.60 mm or less.

If the thickness of the sliding layer is less than 0.30 mm, when the surface roughness Rz of the first surface is increased, a portion where the thickness of the sliding layer is locally reduced is formed, and the sliding layer may be warped. There is. Therefore, by setting the thickness of the sliding layer to 0.30 mm or more, it is possible to reliably prevent the sliding layer from being warped. Therefore, the liner can be prevented from coming off from the cap body, and the tightness of the container can be reliably maintained.
On the other hand, if the thickness of the sliding layer exceeds 0.60 mm, the sliding layer (liner) becomes difficult to bend, and it is difficult to reliably arrange the sliding layer in a predetermined position when fitting it into the cap body. Become. Therefore, there is a possibility that the liner may be improperly attached to the cap body.

In a preferred embodiment of the cap with a liner of the present invention, the sealing layer is made of a styrene-based elastomer, and the weight of the sealing layer is 380 mg or less.

By forming the surface roughness Rz of the first surface of the sliding layer to 5.0 μm or more and 50.0 μm or less in advance, the fluidity of the molten resin can be improved at the time of molding the sealing layer, so that the sealing layer can be molded. The supply amount of the molten resin (weight of the sealing layer) can be reduced as compared with the conventional case. For example, in a sealing layer made of a styrene-based elastomer (TPS), even if the amount of molten resin supplied, which was conventionally required to be 400 mg, is reduced to 380 mg or less and the weight of the sealed layer is reduced to 380 mg or less, the peripheral edge of the sealed layer. It is possible to prevent a lacking portion from being formed in the portion. The preferable weight of the sealing layer is 350 mg or more.

The method for manufacturing a cap with a liner of the present invention is a cap that is attached to the mouth of a container and can seal the mouth, and has a top plate and a cylindrical portion substantially hung from the peripheral edge of the top plate. A sliding layer that slides on the top plate portion, and a sealing layer that is laminated on the sliding layer and formed to be softer and have a smaller outer diameter than the sliding layer and come into contact with the container. A method of manufacturing a cap with a liner provided with a liner, wherein the sliding layer has a surface roughness Rz of more than 20.0 μm on the first surface on the laminated surface side on which the sealing layer is laminated. The molten resin is formed to be 0 μm or less , the molten resin is supplied to the center on the first surface of the sliding layer installed in the cap body, and the molten resin is pressed by a mold for forming a sealing layer in a radial pattern. It has a liner forming step of forming the sealing layer by molding while spreading the resin, and forming a liner in which the sliding layer and the sealing layer are laminated.

Since the liner formed by the liner forming step has the surface roughness Rz of the first surface of the sliding layer formed to be 5.0 μm or more and 50.0 μm or less in advance, the temperature of the molten resin is lowered due to the unevenness of the first surface. Can be suppressed and the resistance between the first surface and the molten resin can be kept small, and when the mold for forming the sealing layer is brought into contact with the first surface during molding of the sealing layer, the inside space of the mold is reduced. Air can be smoothly discharged to the outside from the peripheral edge. Therefore, the molten resin can be smoothly and radially flowed from the inside to the outside in the radial direction in the internal space of the mold, and the molten resin can be filled up to the peripheral edge of the internal space. Therefore, it is possible to prevent the formation of a missing portion on the peripheral edge of the sealing layer, and it is possible to increase the yield of the liner.

Further, as described above, since the surface roughness Rz of the first surface of the sliding layer is formed to be 5.0 μm or more and 50.0 μm or less, the molten resin becomes uneven on the first surface during molding of the sealing layer. By deeply penetrating and curing the molten resin in this state, the adhesive strength between the sliding layer and the sealing layer can be maintained high. Therefore, the sealing layer does not peel off from the sliding layer, and the sealing layer of the liner can be surely brought into contact with the mouth when the cap with liner and the container are attached, so that the sealing property of the bottle can with cap Can be reliably maintained.

According to the present invention, it is possible to prevent the formation of a missing portion during molding of the sealing layer, and it is possible to increase the yield of the liner, so that the sealing property of the container can be improved.

It is a front view of the cap with a liner in which half of the cap with a liner of the embodiment of the present invention has a cross section passing through a can shaft, and is a state before the cap with a liner is wound around a container. It is explanatory drawing of each process explaining the manufacturing method of the cap with a liner. It is an enlarged cross-sectional view of a part of the mold for forming a sealing layer at the time of starting molding of a sealing layer in a liner forming process. It is an enlarged cross-sectional view of a part of the mold for forming a sealing layer at the time of finishing molding of a sealing layer in a liner forming process. It is a front view of the cap with a liner shown in FIG. 1 and the bottle can to which the cap with a liner is attached, each having a cross section of half passing through a can shaft. It is sectional drawing of the main part which made the vicinity of the mouth part of the bottle can with a cap which attached the cap with a liner shown in FIG. 1 through the can shaft.

Hereinafter, embodiments of a cap with a liner and a method for manufacturing the same according to the present invention will be described with reference to the drawings.
The cap with a liner of the present embodiment is attached to the mouth of a container such as a metal bottle can of aluminum or an aluminum alloy having a diameter of 38 mm, and seals the mouth.

FIG. 1 is a front view showing a half of the liner-attached cap 101 manufactured in the present embodiment with a cross section (a cross section passing through a can shaft), and shows a state before mounting the container. Further, in FIG. 5, half of each of the cap 101 with a liner shown in FIG. 1 and the bottle can 201 (container referred to in the present invention) to which the cap 101 with a liner is mounted has a cross section (can shaft). (Cross section through) is shown. Further, in FIG. 5, both the cap 101 with a liner and the bottle can 201 are shown in a state before mounting. On the other hand, FIG. 6 is a cross-sectional view of a main part of the bottle can 301 with a cap in which the cap 101 with a liner is wound around the mouth 214 of the bottle can 201, and is an enlarged view of the vicinity of the mouth 214 of the bottle can 201.

Further, FIG. 2 is an explanatory diagram schematically showing each step of the method for manufacturing a cap with a liner according to the embodiment of the present invention. Further, FIGS. 3 and 4 are explanatory views for explaining the liner forming step in each step of the method for manufacturing the cap with a liner.
In the following description, the directions shown in FIGS. 1, 5 and 6 shall be defined as the vertical direction.

As shown in FIG. 1, the cap 101 with a liner before mounting the container has a cap body 10 formed in a cup shape and a liner 20 provided on the inner surface of the cap body 10.

The cap body 10 is formed by molding, for example, a metal plate material such as aluminum or an aluminum alloy whose inner and outer surfaces are painted. As shown in FIG. 1, the cap body 10 is attached to the mouth portion 214 of the bottle can 201 from the disk-shaped top plate portion 11 and the peripheral edge of the top plate portion 11 along the axial direction O. It has a cylindrical cylindrical portion 12 that is substantially suspended. Further, as shown in FIG. 1, the cylindrical portion 12 has a knurl recess 121 and a vent hole 122, a female screw forming portion 123, a slit 124, and a bridge in this order from the base end side to the tip end side on the top plate portion 11 side. 125 and a hem 126 are formed.

Of these, the knurl recess 121 formed at a position close to the top plate portion 11 on the upper portion of the cylindrical portion 12 applies a frictional force to the hand when the cap is opened. Further, the vent hole 122 is for releasing the internal pressure at the time of opening, and a plurality of the knurl recesses 121 and the vent hole 122 are formed in the circumferential direction of the cylindrical portion 12. Further, the upper piece 131 and the lower piece 132 of the vent hole 122 are formed in a state of being pushed inward in the radial direction, so that the liner 20 is arranged between the upper piece 131 and the top plate portion 11. It is stuck. The tip of the lower piece 132 is formed at a position where it is pushed inward in the radial direction from the tip of the upper piece 131. As a result, when the sliding layer 21 of the liner 20, which will be described later, is fitted into the cap body 10, the peripheral edge portion (outer peripheral portion) of the sliding layer 21 does not come into contact with the upper piece 131, and the sliding layer 21 Can be smoothly pushed into a predetermined position by sliding the inner surface of the lower piece 132.

A plurality of slits 124 are formed intermittently in the circumferential direction at the lower portion of the cylindrical portion 12, and a bridge 125 is formed between the adjacent slits 124, and the cylindrical portion 12 is formed through the slits 124. The upper part 127 and the lower part 128 are separated from each other, and the upper part 127 and the lower part 128 are connected by a plurality of bridges 125 formed between the slits 124.

The liner 20 includes a sliding layer 21 arranged on the inner surface side of the top plate portion 11 of the cap body 10, and a sealing layer 22 laminated on the sliding layer 21. In this case, the liner 20 is rotatably installed with respect to the cap body 10.
The sliding layer 21 is formed of polypropylene or the like in a disk shape (disk shape), and is slidably formed on the inner surface of the top plate portion 11.

Specific examples of the material of the sliding layer 21 include polypropylene (PP), high-density polyethylene (HDPE), polyamide (PA, commonly known as nylon), polycarbonate (PC), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). ), Polyacrylonitrile (PAN), polyvinyl chloride (PVC) and the like can be adopted.
As the sliding layer 21, a multi-layer sheet such as a three-layer structure sheet in which ethylene-vinyl alcohol copolymer resin (EVOH) is laminated between polypropylene can also be adopted.

In the sliding layer 21, the first surface 251 on the laminated surface side on which the sealing layer 22 is laminated has a surface roughness Rz of 5.0 μm or more and 50.0 μm or less. The surface roughness Rz of the first surface 251 is more preferably 20.0 μm or more and 40.0 μm or less. The surface roughness Rz is determined by the maximum height conforming to JIS B 0601: 2001 in the JIS standard (Japanese Industrial Standards).
The surface roughness Rz of the second surface 252, which is the other surface of the sliding layer 21 and is the sliding surface with the top plate portion 11, is not particularly limited, but is the surface of the second surface 252. The roughness Rz is preferably in the range of 5 μm or less (Rz <5 μm).

In this case, the sliding layer 21 of the liner 20 is formed so as to be slidable with the inner surface of the top plate portion 11 of the cap body 10, and is formed between the second surface 252 of the sliding layer 21 and the inner surface of the top plate portion 11. A non-volatile organic liquid such as silicone oil or glycerin is applied between them. The non-volatile organic liquid is applied in order to reduce the opening torque value at the time of opening the cap and to improve the gas barrier property that suppresses the ingress of gas. Then, in order to exert the effect, it is necessary to interpose a necessary amount of the non-volatile organic liquid between the top plate portion 11 and the sliding layer 21. Therefore, if the surface roughness Rz of the second surface 252 becomes too large, it is necessary to increase the coating amount of the non-volatile organic liquid by the amount of the unevenness of the second surface 252. Therefore, as described above, by setting the surface roughness Rz of the second surface 252 to 5 μm or less, the coating amount of the non-volatile organic liquid can be reduced, which is economically preferable.

The hardness of the sliding layer 21 is preferably 70 or more and 85 or less in terms of type D durometer hardness. Type D durometer hardness is measured by type D in accordance with JIS K 7215 in the JIS standard.
Further, the thickness of the sliding layer 21 is formed to be substantially constant. The thickness of the sliding layer 21 is preferably 0.30 mm or more and 0.60 mm or less.

Further, the sealing layer 22 is formed of an elastomer resin or the like softer than the sliding layer 21, and as shown in FIG. 6, hits the mouth portion 214 (curl portion 218) of the bottle can 201 when the cap 101 with a liner is closed. It is configured so that the inside of the bottle can 201 can be sealed in contact with the bottle can 201.

Specific examples of the material of the sealing layer 22 include styrene-based elastomer (TPS), polyolefin-based elastomer (TPO), urethane-based elastomer (TPU), polyamide-based elastomer (TPEA), polyester-based elastomer (TPEE), and polychloride. A vinyl elastomer (PVC-TPE) or the like can be adopted.

The sealing layer 22 is preferably made of a material that can be thermally bonded to the sliding layer 21. For example, when the sliding layer 21 is polypropylene (PP), the sealing layer 22 is made of a styrene-based elastomer (TPS) or a polyolefin-based elastomer (TPO). Are suitable. When the sliding layer 21 is polyethylene terephthalate (PET), a polyester elastomer (TPEE) is suitable for the sealing layer 22, and when the sliding layer 21 is vinyl chloride (PVC), a polyvinyl chloride elastomer (PVC-TPE) is used. Are suitable.
In particular, when the sliding layer 21 is made of polypropylene (PP), which is economically and has excellent heat resistance, the sealing layer 22 has excellent adhesion to polypropylene and has good retort resistance. ) Is preferable.

In this embodiment, the hardness comparison between the sliding layer 21 and the sealing layer 22 is determined by the type D durometer hardness (JIS K 7217). Further, the outer diameter of the sealing layer 22 is formed to be smaller than the outer diameter of the sliding layer 21. In FIG. 1, the sealing layer 22 is composed of an annular sealing portion 23 in contact with the curl portion 218 of the mouth portion 214 and a thin-walled portion 24 formed inside the sealing portion 23, and the sealing portion 23 is larger than the thin-walled portion 24. It is formed thick. The thickness of the sealing layer 22 is not particularly limited, but for example, the thickness of the sealing portion 23 is formed to be 0.7 mm or more and 1.0 mm or less, and the thickness of the thin portion 24 is formed to be 0.2 mm or more and 0.3 mm or less. ..

As shown in FIGS. 5 and 6, the cap 101 with a liner configured in this way is put on the mouth portion 214 of the bottle can 201, and the liner 20 on the inner surface of the top plate portion 11 of the cap body 10 is curled. By performing the capping process in the state of being pressed against 218, the cap 101 with a liner is attached to the mouth portion 214 of the bottle can 201 to form a bottle can with a cap (container with a cap) 301. Specifically, after filling the inside of the bottle can 201 with the contents, the female screw forming portion 123 of the cylindrical portion 12 of the cap body 10 is screwed along the male screw portion 216 formed in the mouth portion 214 to form the female screw portion. The cap 101 with a liner is attached to the mouth portion 214 by molding 129 (see FIG. 6) and engaging the hem portion 126 of the cylindrical portion 12 with the lower portion of the bulging portion 215. As a result, the bottle can 301 with a cap in which the mouth portion 214 of the bottle can 201 is sealed by the cap 101 with a liner is manufactured.

In the bottle can 301 with a cap configured in this way, when the upper 127 above the bridge 125 of the cap 101 with a liner is rotated around the can axis with respect to the bottle can 201, the upper 127 is the male screw portion 216. The lower part 128 below the bridge 125 is locked to the bulge 215, so that the bridge 125 is broken and the upper part 127 of the cylindrical part 12 is broken. And the lower 128 are separated. Then, the upper portion of the cap 101 with a liner (upper part 127 of the cylindrical portion 12) is removed from the mouth portion 214, and the lower portion of the cap 101 with a liner (lower portion 128 of the cylindrical portion 12) is left in the mouth portion 214. .. Further, by removing the upper part of the cap 101 with a liner from the mouth portion 214, the mouth portion 214 can be opened and the contents inside the bottle can 201 can be taken out. On the other hand, the mouth portion 214 of the bottle can 201 can be reclosed by reattaching the upper portion of the removed cap 101 with a liner to the mouth portion 214.

Next, the method for manufacturing the cap with a liner of the present invention will be described by taking as an example the case of manufacturing the cap 101 with a liner configured as described above.
As shown in the schematic view of FIG. 2, the method for manufacturing the cap 101 with a liner of the present embodiment is configured to include a cap body forming step of forming the cap body 10 and a liner forming step of forming the liner. ..

<Cap body forming process>
As shown in FIG. 2, a metal plate 40 for forming the cap body 10 is prepared. Usually, a plate material 40 whose inner and outer surfaces are painted is used. In this case, the plate material 40 is coated with a size coat and a top coat on the inner surface side of the cap body 10. Further, the surface of the cap body 10 on the outer surface side is coated with a top coat (gloss) after a size coat is printed as needed.

Then, a lubricant is applied to the plate material 40 as needed, and the plate material 40 is punched into a cup shape by press working to form a cap body 10 having a top plate portion 11 and a cylindrical portion 12. Further, the cap body 10 is processed into a shape such as a knurl recess 121 or a vent hole 122 along the circumferential direction of the cylindrical portion 12.

<Liner forming process>
As shown in FIGS. 2 to 4, the liner forming step is performed in a state where the cap body 10 is placed so that the open end is facing upward.
First, a disk-shaped sliding layer 21 is arranged on the inner surface of the top plate portion 11 of the cap body 10. The outer diameter of the sliding layer 21 is set on each upper piece so that the peripheral edge portion of the sliding layer 21 is arranged radially outside the position of the tip (the tip on the inner side in the radial direction) of the upper piece 131 of the vent hole 122. It is formed larger than the inscribed circle in contact with the tip of 131. Therefore, the peripheral edge portion of the sliding layer 21 is supported by each upper piece 131 and does not come off from the cap body 10, and is arranged in a non-adhesive state on the inner surface of the top plate portion 11. Before inserting the sliding layer 21, a non-volatile organic liquid is applied to the inner surface of the top plate portion 11 of the cap body 10.

In this case, the sliding layer 21 is formed by punching a large-sized or roll-shaped continuous hard sheet. The hard sheet is formed, for example, by rolling a synthetic resin plate between two rollers, and is formed to have a uniform thickness as a whole. At this time, by forming fine irregularities on the surface of the roller that abuts on one surface of the hard sheet by sandblasting or the like, it becomes the first surface of the sliding layer 21 when the hard sheet is rolled. The unevenness of the surface of the roller is transferred to the surface of the roller, and a surface having a desired surface roughness Rz is formed on one surface of the hard sheet. In this way, the surface roughness Rz of one surface of the hard sheet can be adjusted by adjusting the unevenness of the surface of the roller, and by punching out the hard sheet thus formed, the surface roughness Rz of the first surface can be adjusted. The sliding layer 21 is formed in which the width is adjusted to be 5.0 μm or more and 50.0 μm or less.

The sliding layer 21 can also be formed by an in-shell molding method in which the cap body 10 is molded. In this case, a molten resin such as molten polypropylene is supplied to the inner surface of the top plate portion 11 of the cap body 10, and the sliding layer 21 is formed using a mold for molding the sliding layer. Further, by forming fine irregularities on the surface of the mold for molding the sliding layer by sandblasting or the like, the mold can be formed on the first surface 251 of the sliding layer 21 at the same time as the sliding layer 21 is molded. The unevenness is embossed. As a result, the surface roughness Rz of the first surface 251 can be formed to be 5.0 μm or more and 50.0 μm or less.

Next, the sealing layer 22 is formed by an in-shell molding method in which the cap body 10 is molded. The sliding layer 21 is inserted into the cap body 10 in advance. At this time, the sliding layer 21 is arranged so that the second surface 252 is in contact with the inner surface of the top plate portion 11 of the cap body 10.
Then, as shown in FIG. 3, the molten resin R is supplied (dropped) from an extruder (not shown) to the center of the first surface 251 with the sliding layer 21 arranged in the cap body 10. Subsequently, as shown in FIGS. 3 and 4, the sealed layer 22 is formed by pressing with the mold M for forming the sealing layer and molding the molten resin R by molding.

As shown in FIGS. 3 and 4, for example, the mold M for forming the sealing layer slides with a sleeve punch 410 that contacts the first surface 251 of the sliding layer 21 and defines the outer diameter of the sealing layer 22. It includes a center punch 420 which is arranged at a distance from the first surface 251 of the layer 21 and defines the thickness of the sealing layer 22, and a pedestal 430 on which the cap body 10 is placed. The sealing layer 22 slides by supplying the molten resin R onto the first surface 251 of the sliding layer 21 and then pressing the molten resin R with the center punch 420 and the sleeve punch 410 of the cooled mold M. It is formed by filling the internal space (cavity space) surrounded by the first surface 251 of the moving layer 21, the inner peripheral surface 411 of the sleeve punch 410, and the pressing surface 421 at the tip of the center punch 420 with the molten resin R. ..

The sleeve punch 410 is formed in a cylindrical shape, and its outer peripheral surface is provided smaller than the inscribed circle in contact with the tip of the upper piece 131. Further, a center punch 420 is inserted inside the sleeve punch 410 so that it can be moved forward and backward. Although not shown, the sleeve punch 410 is provided with an urging means (spring or the like) for pressing and urging the sleeve punch 410 in the tip direction (downward in FIGS. 3 and 4). Then, by the urging force of the urging means, the sleeve punch 410 presses the first surface 251 of the sliding layer 21 in the cap body 10, and the inner peripheral surface 411 forms the outside of the internal space for forming the sealing layer 22. Form a perimeter.

The center punch 420 is formed in a cylindrical shape, and the pressing surface 421 at the tip thereof has an annular recess 423 for forming the annular seal portion 23 and a thickness smaller than that of the seal portion 23, as shown in FIG. It has a cylindrical convex portion 424 for forming the thin-walled portion 24. The cylindrical convex portion 424 is arranged inside the annular recess 423 in the radial direction.

As shown in FIG. 3, the cap body 10 is arranged with the outer surface of the top plate portion 11 installed on the pedestal 430, and the sliding layer 21 is in contact with the inner surface of the top plate portion 11 so that the second surface 252 is in contact with the inner surface. Be placed. In this state, a certain amount of the molten resin R is extruded from an extruder (not shown), and the molten resin R is supplied to the center of the first surface 251 of the sliding layer 21 arranged in the cap body 10. Then, the molten resin R is immediately pressed by the cooled sleeve punch 410 and the center punch 420.

Immediately after the molten resin R is supplied onto the first surface 251 of the sliding layer 21, the surface roughness Rz of the first surface 251 is formed to be 5.0 μm or more and 50.0 μm or less. , It is supported by the convex portion without entering the concave portion of the fine unevenness of the first surface 251. Therefore, the contact area between the first surface 251 of the sliding layer 21 and the molten resin R is kept small, and the temperature drop of the molten resin R is suppressed.

Further, when the pressing surface 421 of the center punch 420 starts pressing the molten resin R, as shown in FIG. 3, the surface of the cylindrical convex portion 424 first comes into contact with the molten resin R. Then, when the center punch 420 and the sleeve punch 410 move in a direction further approaching the sliding layer 21, the molten resin R pushed by the center punch 420 is moved outward in the radial direction as shown by an arrow A in FIG. It flows toward and spreads radially. At this time, since the first surface 251 of the sliding layer 21 is formed with irregularities having a predetermined surface roughness Rz, the resistance between the convex portion of the first surface 251 and the molten resin R is maintained small. , The molten resin R flows smoothly from the inside to the outside in the radial direction.

Further, as shown in FIG. 4, when the center punch 420 and the sleeve punch 410 move in the direction closest to the sliding layer 21, the tip (pressing surface 412) of the sleeve punch 410 becomes the first surface of the sliding layer 21. Upon contact with 251 and the internal space being closed, the molten resin R is further expanded outward in the radial direction to reach the inside of the annular recess 423. Also in this case, since the surface roughness Rz of the first surface 251 is provided between the sleeve punch 410 and the sliding layer 21 to be 5.0 μm or more and 50.0 μm or less, the internal space of the mold M is provided. A gap is maintained between the outside and the outside where air can move. Therefore, the air in the internal space is smoothly discharged to the outside from between the sleeve punch 410 and the sliding layer 21, that is, from the peripheral edge of the internal space. Therefore, as shown in FIG. 4, the molten resin R can be smoothly filled up to the peripheral edge of the internal space (cavity space), and the molten resin R is uniformly filled in the entire region of the internal space.

Further, in the latter stage of molding the molten resin R by the mold M, the molten resin R is pressed toward the first surface 251 of the sliding layer 21 by the center punch 420, so that the sliding layer 21 and the molten resin R are formed. The air intervening between the two is finally discharged to the outside from the peripheral edge of the internal space through the recess of the first surface 251. Therefore, the molten resin R penetrates deeply into the unevenness of the first surface 251. Then, by cooling in this state and curing the molten resin R, a circular sealing layer 22 coaxial with the sliding layer 21 and having a small diameter is formed, and the liner in which the sliding layer 21 and the sealing layer 22 are laminated is formed. 20 is formed. At the same time, a cap 101 with a liner including the liner 20 is manufactured.

In this embodiment, the sliding layer 21 and the sealing layer 22 are adhered to each other at the time of molding by selecting each material. However, in order to further enhance the adhesive force between the sliding layer 21 and the sealing layer 22, the first surface 251 of the sliding layer 21 is subjected to corona discharge treatment, glow discharge treatment, plasma treatment, anchor coating treatment, adhesive coating, etc. Surface treatment may be performed. The surface treatment of the first surface 251 may be performed after the sliding layer 21 is arranged in the cap body 10.

As described above, in the cap 101 with a liner of the present embodiment, the surface roughness Rz of the first surface 251 of the sliding layer 21 is formed in advance to 5.0 μm or more and 50.0 μm or less, so that the sealing layer is sealed. At the time of molding 22 When the surface 251 is brought into contact with the surface 251 the air in the internal space (cavity space) of the mold M can be smoothly discharged to the outside from the peripheral edge portion. Therefore, the molten resin R can be smoothly and radially flowed from the inside to the outside in the radial direction in the internal space of the mold M, and the molten resin R can be uniformly filled up to the peripheral edge of the internal space. Therefore, it is possible to prevent the formation of a missing portion on the peripheral edge of the sealing layer 22, and it is possible to increase the yield of the liner 20. Further, the sealing portion 23 of the sealing layer 22 can be formed at a uniform height (thickness) without variation in the circumferential direction. Therefore, by attaching the liner-attached cap 101 formed in this way to the bottle can 201, the sealing performance of the cap-attached bottle can 301 can be improved.

Further, in the cap 101 with a liner, the surface roughness Rz of the first surface of the sliding layer is formed to be 5.0 μm or more and 50.0 μm or less in advance, so that the fluidity of the molten resin R during molding of the sealing layer 22 is formed. Therefore, the supply amount of the molten resin R for molding the sealing layer 22 (weight of the sealing layer 22) can be reduced as compared with the conventional case. For example, in the sealing layer 22 made of a styrene-based elastomer (TPS), the amount of molten resin R supplied, which was conventionally required to be 400 mg, is reduced to 380 mg or less, and the sealing layer 22 is sealed even if the weight is 380 mg or less. It is possible to prevent the formation of a missing portion on the peripheral edge of the layer 22. In this case, the preferable weight of the sealing layer 22 is 350 mg or more.

Further, as described above, since the surface roughness Rz of the first surface 251 of the sliding layer 21 is formed to be 5.0 μm or more and 50.0 μm or less, the molten resin R is first formed when the sealing layer 22 is molded. It penetrates deeply into the unevenness of the surface 251 and enhances the adhesion with the sliding layer 21. Since the molten resin R is cured in this state, the adhesive area between the sliding layer 21 and the sealing layer 22 is increased, and the adhesive strength between the sliding layer 21 and the sealing layer 22 can be increased. Therefore, the sealing layer 22 does not peel off from the sliding layer 21, and when the cap 101 with liner and the bottle can 201 are attached, the sealing layer 22 of the liner 20 is surely brought into contact with the mouth portion 214 of the bottle can 201. This makes it possible to reliably maintain the sealing property of the bottle can 301 with a cap.

If the surface roughness Rz of the first surface 251 of the sliding layer 21 is less than 5.0 μm, a sufficient space for air to move between the sleeve punch 410 and the sliding layer 21 should be secured. When molding the sealing layer 22, it becomes difficult to discharge air from the peripheral edge of the internal space (cavity space) to the outside. Further, when the surface roughness Rz of the first surface 251 exceeds 50.0 μm, the molten resin R tends to leak from the peripheral edge of the internal space to the outside when the sealing layer 22 is molded. In this case, it becomes difficult to fill the molten resin R up to the peripheral edge at a diagonal position of the portion where the molten resin R leaks, and there is a possibility that a thin portion may be formed in the sealing layer 22. The optimum range of the surface roughness Rz of the first surface 251 is 20.0 μm or more and 40.0 μm or less.

From the viewpoint of improving the air release from the peripheral edge of the internal space of the mold M for forming the sealing layer to the outside, the sliding layer 21 is formed with fine irregularities on the pressing surface 412 at the tip of the sleeve punch 410. It is also possible to secure a gap for improving air leakage between the first surface 251 of the above and the pressing surface 412 of the sleeve punch 410. However, when the pressing surface 412 of the sleeve punch 410 is roughly formed, when the sleeve punch 410 is inserted into the cap body 10, the pressing surface 412 comes into contact with the inner surface of the cap body 10 to press the inner surface of the cap body 10. It may hurt and is not preferable.

Further, in the present embodiment, the hardness of the sliding layer 21 is set to 70 or more and 85 or less in terms of the type D durometer hardness, and the type D durometer hardness is set to 70 or more, so that the mold M for forming the sealed layer is slid. Even when pressed against the layer 21, the fine uneven shape of the first surface 251 is not crushed, and the unevenness can be maintained satisfactorily. Therefore, air can be smoothly discharged from between the mold M (sleeve punch 410) and the sliding layer 21, and it is possible to reliably prevent the formation of a missing portion of the sealing layer 22.

If the type D durometer hardness of the sliding layer 21 is less than 70, when the mold M (sleeve punch 410) is pressed against the sliding layer 21, the unevenness of the first surface 251 is crushed at the contact portion. It becomes difficult to secure a sufficient gap between the sleeve punch 410 and the sliding layer 21. Therefore, air leakage from the peripheral edge of the internal space (cavity space) may be hindered. On the other hand, when the type D durometer hardness of the sliding layer 21 exceeds 85, the hardness of the sliding layer 21 increases, so that the liner 20 is less likely to be deformed. Therefore, when the cap 101 with a liner is attached to the mouth portion 214 of the bottle can (container) 201, the liner 20 is less likely to be deformed along the shape of the mouth portion 214 (curl portion 218), and the sealing layer 22 and the mouth Adhesion with the portion 214 may be impaired.

On the other hand, in the present embodiment, the thickness of the sliding layer 21 is 0.30 mm or more and 0.60 mm or less, and the thickness of the sliding layer 21 is 0.30 mm or more, so that the sliding layer 21 is warped. It can be reliably prevented. Therefore, it is possible to prevent the liner 20 from coming off from the cap body 10, and it is possible to reliably maintain the sealing property of the bottle can 301 with a cap using the cap 101 with a liner.

If the thickness of the sliding layer 21 is less than 0.30 mm, a portion where the thickness of the sliding layer 21 is locally reduced is formed when the surface roughness Rz of the first surface 251 is increased, and the sliding layer is formed. There is a risk that the 21 will warp. On the other hand, if the thickness of the sliding layer 21 exceeds 0.60 mm, the sliding layer 21 (liner 20) is less likely to bend, and when the sliding layer 21 is fitted into the cap body 10, it is surely placed in a predetermined position. It becomes difficult to place. Therefore, there is a possibility that the liner 20 may be improperly attached to the cap body 10.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the container to which the cap with a liner is attached is described as a metal bottle can, but the container in the present invention is not limited to the metal bottle can, and is a bottle. In addition to cans, containers such as glass bottles and PET bottles are also included.

Next, the result of producing and evaluating the cap with a liner according to the present invention will be described.
As an example, a cap with a liner having a surface roughness Rz of the first surface of the sliding layer of 5.0 μm or more and 50.0 μm or less was produced, and as a conventional example, the surface roughness Rz of the first surface of the sliding layer was increased. A cap with a liner having a surface roughness Rz of 4.5 μm, which is outside the range of 5.0 μm or more and 50.0 μm, was produced.

For the cap body, paint such as epoxyphenol and polyester is applied to the inner and outer surfaces of an aluminum alloy plate with a thickness of 0.235 mm, which is punched into a cup shape by press working, and then knurled recesses and vent holes are formed in the cylindrical part. Made by processing. The cap body was formed in a size for mounting a bottle can with a diameter of 38 mm.

The hard sheet used as the material of the sliding layer was formed of polypropylene (PP) having a type D durometer hardness of 75 and a thickness of 0.45 mm. Further, the surface roughness Rz of one surface (the surface to be the first surface) of the hard sheet was adjusted to form the four types shown in Table 1. Then, these hard sheets were punched out in a disk shape to form four types of sliding layers. Of the four types of sliding layers, the arithmetic mean roughness Ra of the first surface when the surface roughness Rz is 4.5 μm is 0.9 μm, and the first surface roughness Rz is 26.0 μm. The arithmetic mean roughness Ra of one surface was 5.2 μm.

These sliding layers are inserted into the cap body so that the second surface is in contact with the inner surface of the top plate of the cap body, and the first sliding layer is formed by the same in-shell molding method as the manufacturing method of the embodiment. A liner having a sealing layer laminated on the surface was formed. As the elastomer (molten resin) used as the material of the sealing layer, a styrene-based elastomer (TPS) having excellent adhesiveness to polypropylene (PP) and good retort resistance was used.
The supply amount (elastomer weight) of the molten resin forming the sealing layer was based on 400 mg and varied for each type of sliding layer. Further, the supply position (drop position) of the molten resin was set to a position deviated from the center of the sliding layer (first surface), and molding was performed under conditions in which the sealing layer was likely to be chipped.

Then, these caps with liners were visually inspected for chipping of the sealing layer. The results are shown in Table 1.

As can be seen from the results in Table 1, the samples 2 to 4 in which the surface roughness Rz of the first surface of the sliding layer was formed in the range of 5.0 μm or more and 50.0 μm or less were compared with the sample 1 outside the range. As a result, the incidence of chipping of the sealing layer could be significantly reduced. Further, in Samples 2 to 4, even if the weight of the elastomer was reduced as compared with Sample 1, the occurrence rate of chipping of the sealing layer could be reduced.

From the above results, by setting the surface roughness Rz of the first surface of the sliding layer to 5.0 μm or more and 50.0 μm or less, the occurrence of chipping of the sealing layer can be suppressed. Further, the cap with liner (Samples 2 to 4) of the example is economically superior because the weight of the elastomer to be supplied can be reduced as compared with the cap with liner (Sample 1) of the conventional example.

10 Cap body 11 Top plate 12 Cylindrical portion 20 Liner 21 Sliding layer 22 Sealing layer 23 Sealing portion 24 Thin-walled portion 40 Plate material 101 Liner cap 121 Nar recess 122 Vent hole 123 Female screw formation planned portion 124 Slit 125 Bridge 126 Hem portion 127 Upper 128 Lower 129 Female thread 131 Upper piece 132 Lower piece 201 Bottle can (container)
214 Mouth 215 Swelling 216 Male thread 218 Curling 251 First surface 252 Second surface 301 Capped bottle can (capped container)
410 Sleeve punch 411 Inner peripheral surface 412 Pressing surface 420 Center punch 421 Pressing surface 423 Circular concave part 424 Cylindrical convex part 430 Pedestal M Mold for sealing layer molding R Molten resin

Claims (5)

A cap that is attached to the mouth of a container and can seal the mouth.
A cap body having a top plate portion and a cylindrical portion substantially hung from the peripheral edge of the top plate portion,
A liner provided on the inner surface of the top plate portion is provided.
The liner is arranged on the inner surface side of the top plate portion and has a sliding layer that slides on the top plate portion, and is laminated on the sliding layer to be formed to be softer and have a smaller outer diameter than the sliding layer. With a sealing layer that comes in contact with
A cap with a liner, wherein the surface roughness Rz of the first surface of the sliding layer on the laminated surface side of the sealing layer exceeds 20.0 μm and is 40.0 μm or less. The cap with a liner according to claim 1, wherein the hardness of the sliding layer is 70 or more and 85 or less in terms of type D durometer hardness. The cap with a liner according to claim 1 or 2, wherein the thickness of the sliding layer is 0.30 mm or more and 0.60 mm or less. The cap with a liner according to any one of claims 1 to 3, wherein the sealing layer is made of a styrene-based elastomer and the weight of the sealing layer is 380 mg or less. A cap that is attached to the mouth of a container and can seal the mouth.
A sliding layer that slides on the top plate and a sliding layer that is laminated on the sliding layer are contained in a cap body that has a top plate and a cylindrical portion that is substantially hung from the peripheral edge of the top plate. It is a method of manufacturing a cap with a liner provided with a liner provided with a sealing layer which is softer and has a smaller outer diameter and is in contact with the container.
The sliding layer is formed so that the surface roughness Rz of the first surface on the laminated surface side on which the sealing layer is laminated exceeds 20.0 μm and is 40.0 μm or less .
The molten resin is supplied to the center of the sliding layer installed in the cap body on the first surface, and the molten resin is pressed by a mold for forming a sealing layer and spread radially while being molded. A method for manufacturing a cap with a liner, which comprises a liner forming step of forming a sealing layer and forming a liner in which the sliding layer and the sealing layer are laminated.

Images