JP6200717B2 - Resin cap - Google Patents

Description

  The present invention relates to a resin cap having a liner made of a hot melt composition, and more particularly to a resin cap in which a liner is formed smoothly at a desired position and can exhibit excellent sealing properties.

A resin liner is provided on the inner surface side of the top plate portion of the container lid to improve the sealing performance of the container in close contact with the tip of the container mouth.
The method of forming the resin liner varies depending on the material constituting the liner. For example, in the case of a liner made of a thermoplastic resin such as polyethylene, an injecting mold for the molten resin made of the thermoplastic resin supplied in the cap is used. A shell mold method (Patent Document 1) or an insert molding method (Patent Document 2) formed by injection molding of a thermoplastic resin using a cap as a part of a mold has been proposed.
In the case of a liner made of a vinyl chloride resin, a method of forming by supplying vinyl chloride plastisol by spin lining (Patent Document 3), and in the case of a liner made of natural rubber, water-dispersed latex such as natural rubber. (Patent Document 4), or in the case of a liner made of a urethane-based elastomer, a method of forming by mixing an isocyanate component and a polyol component and then crosslinking (Patent Document 4) 5) etc.

  However, although a liner made of a thermoplastic resin is excellent in water resistance, a liner using an in-shell mold or insert molding requires a dedicated mold to form the liner, and a liner using plastisol A plasticizer is essential, and the odor derived from the plasticizer is a problem. In addition, an oven for baking during plasticization is required, and certain equipment is required. In addition, when rubber latex is used, a long drying process is required to dry the moisture in the material. Furthermore, a liner made of a urethane-based elastomer has a low moisture barrier property and needs to be heated in an oven for crosslinking in forming.

From such a point of view, the present applicant does not have any problems such as odor and moisture barrier property, and does not require special equipment, and the present applicant has proposed a hot melt composition as a liner material excellent in productivity and economy. Has been proposed (Japanese Patent Application No. 2012-78015).
Since the liner material made of the hot melt composition has higher hardness than the general liner material described above, it seals at the outer corner of the container mouth rather than sealing at the top of the container mouth. It is effective in terms of hermeticity. For this reason, in order to form the liner on the outer peripheral edge of the inner surface of the top plate portion of the cap shell, after applying the hot melt composition, which is a liner material, to the cap shell, the liner material flows to the outer peripheral edge side by further performing afterspin. It is desirable to smooth the liner surface.

JP-A-2-4624 Japanese Patent Laid-Open No. 2001-261054 Japanese Patent Laid-Open No. 3-124572 JP-A-6-255680 JP 2003-137321 A

However, as shown in FIG. 3A to be described later, when a liner material 20 made of a hot melt composition is applied to a conventional cap shell and afterspinning is performed, the liner material 20 in a molten state is formed on the inner surface of the skirt portion. There is a risk that the ring-shaped protrusion 45 will be squeezed out to the outside (indicated by 20a in the figure). In addition, air bubbles 22a and 22b are generated in the liner, and the smoothness of the liner is impaired, and the flexibility of the liner is different between the part where the air bubbles are formed and the part where there are no air bubbles. I found it to happen.
Further, since the amount of the liner material used is large, the economy becomes inferior, and there is a possibility that the advantages of the liner made of the hot melt composition cannot be fully utilized.
Accordingly, the object of the present invention is to provide a hot melt composition having excellent sealing performance, productivity and economic efficiency, even when a liner material made of a hot melt composition is used, and the liner material does not protrude or form bubbles. It is to provide a resin cap having a liner made of material.

According to the present invention, a resin cap shell comprising a top plate portion and a skirt portion depending from the periphery of the top plate portion, and a resin having an annular liner made of a hot melt composition formed on the outer periphery of the inner surface of the top plate portion. In the cap made of the resin, an annular inclined surface is formed at a boundary portion between the inner surface of the top plate portion and the inner surface of the skirt portion of the resin cap shell, and protrudes inward from the inner surface of the skirt portion below the annular inclined surface. An annular protrusion is formed, and a flat portion connected to the annular inclined surface is formed on the inner surface of the top plate portion so that the annular inclined surface increases in the axial thickness toward the outer diameter side of the cap. An annular ridge is formed on the inner surface of the top plate portion of the resin cap shell so as to protrude downward from the flat portion toward the inside of the cap. Side parts side is an inclined surface which thickness in the axial direction is decreased toward the cap outer diameter, a liner made of the hot melt composition, formed above and inclined annular surface and the flat portion on than the annular projection In the closed state where the resin cap is applied to the container mouth portion, a resin cap is provided in which the outer corner portion of the container mouth tip abuts against a liner at a position corresponding to the annular inclined surface. The

In the resin cap of the present invention,
1 . The liner is formed by rotating the cap shell after the hot melt composition is annularly applied to the cap shell surface,
2 . The liner is formed by annularly applying the hot melt composition to the inner surface of the cap shell while rotating the cap shell;
3 . The liner comprises a hot melt composition comprising a thermoplastic resin or a thermoplastic resin composition having a viscosity at 180 ° C. in the range of 400 to 2000 mPa · sec as measured by a B-type viscometer;
4 . The liner has a JIS A hardness of 70 to 95 and a static friction coefficient of 0.10 or less,
Is preferred.

In the resin cap of the present invention, since the annular inclined surface is formed at the boundary portion between the top plate portion inner surface and the skirt portion inner surface of the cap shell, the supply amount of the liner material can be reduced. The material is easy to cool, and the liner that flows radially outward during the so-called after-spin, which smoothes the liner surface by rotating the cap shell after the liner material is supplied, may protrude over the annular protrusion. Effectively prevented.
In addition, the corner portion formed by the inner surface of the top plate portion and the inner surface of the skirt portion of the cap shell is difficult to reach the entire liner forming region and easily causes bubbles. As a result, the generation of bubbles is suppressed, and the smoothness of the liner surface is impaired by the bubbles, and the occurrence of locations where the flexibility of the liner differs depending on the presence or absence of bubbles is effectively prevented.
Furthermore, in the resin cap of the present invention, since the liner is formed smoothly on the annular inclined surface of the cap shell, the liner formed on the annular inclined surface is crimped to the outer corner of the container mouth, It has excellent sealing properties, and since the liner surface is smooth, the opening torque is small and the opening property is excellent.
Furthermore, since the liner is made of a hot-melt composition, it can be supplied by spin lining and has excellent productivity, and it does not need to be baked to form a liner, so no special equipment such as an oven is required. Excellent economic efficiency.

It is the side half sectional view (A) and bottom view (B) of an example of the resin cap of the present invention. It is an expanded sectional view of the liner formation part of the resin cap shown in FIG. It is a figure which shows the state which applies a liner material to a cap shell, (A) is a conventional cap, (B) is a figure which shows the cap of this invention.

The resin cap of the present invention comprises a cap shell 1 and a liner 20 formed on the inner surface of the cap shell 1.
As shown in FIGS. 1 and 2, the cap shell 1 includes a top plate portion 2 and a skirt portion 3 depending from the periphery of the top plate portion 2, and a screw portion 31 of the container mouth portion 30 is formed on the inner surface of the skirt portion 3. And a threaded portion 4 is formed.
On the inner surface side of the top plate portion 2 of the cap shell 1, an annular inclined surface 5 is formed at the boundary portion between the top plate portion 2 and the skirt portion 3, and a flat portion 6 connected to the annular inclined surface is formed in the cap center direction. It extends towards. Moreover, in the specific example shown in FIG.1 and FIG.2, the cyclic | annular protrusion 7 with a smaller diameter in the front-end | tip part 7a is formed in the cap center direction rather than this flat part 6 rather than the internal diameter of the container opening part 30 which applies a cap. In addition, since the annular ridge 7 is formed, it becomes possible to reduce the supply amount of the liner material. In addition, as apparent from FIG. 2, in this embodiment, the annular ridge 7 has the outer surface 7b and the inner surface 7c formed as inclined surfaces, thereby reducing the generation of bubbles as will be described later. Is also possible.
Further, an annular protrusion 8 is formed below the annular inclined surface 5 so as to protrude from the inner surface of the skirt portion 3 toward the inside of the cap. Along the annular inclined surface 5 between the annular protrusion 8 and the annular protrusion 7 A liner 20 having a shape is formed, and as shown in FIG. 2, the liner at a portion corresponding to the outer corner portion 32 of the container mouth portion 30 and the annular inclined surface 5 is pressure-bonded to ensure sealing performance.

FIG. 3 is a view for explaining application of a liner material made of a hot melt composition to a cap shell, and FIG. 3A shows a case where a liner material made of a hot melt composition is supplied in a conventional cap. FIG. 3B shows a case where a liner material made of a hot melt composition is supplied to the cap of the present invention.
In the conventional cap shown in FIG. 3A, an annular ridge 44 is formed on the inner surface of the top plate portion 42, and the annular ridge 44 and the annular projection 45 projecting inward from the skirt portion 43 are defined. When the liner material 20 is supplied to the annular region 46 from the nozzle 21, as described above, the corner portion 47 formed by the annular protrusion 44 and the inner surface of the top plate portion 42 in the annular region, and the inner surface of the skirt portion 43. Like the corner portion 48 formed by the inner surface of the top plate portion 42, a portion where the liner material is difficult to spread occurs, and the air bubbles 22a and 22b are formed, and the smoothness of the liner is impaired. Moreover, since the amount of the liner material 20 is large, the liner material 20 is not only inferior in economic efficiency but also difficult to be cooled, so that it easily flows. As a result, the after-spin gets over the annular protrusion 45 and protrudes outside (in FIG. 3A). , 20a).

On the other hand, as shown in FIG. 3B, in the resin cap of the present invention, the annular region to which the liner material should be supplied is smaller than that in FIG. The amount of the liner material to be supplied is small, and as a result, the supplied liner material is easily cooled, and the liner material 20 spreads radially outward along the annular inclined surface 5 by the centrifugal force during the afterspin. Since it is naturally cooled, the liner material has no risk of getting over the annular protrusion 8.
Further, since the annular inclined surface 5 is formed at the boundary portion between the top plate portion 2 and the skirt portion 3, a corner portion having a small angle that the liner material is difficult to reach is not formed, and as a result, the annular material that supplies the liner material is formed. There is no generation of bubbles in the region, a liner having a smooth surface can be formed, and excellent sealing performance can be secured. Moreover, in the specific example shown in the figure, the outer side surface 7a of the annular ridge 7 formed on the center side of the cap also forms an inclined surface that is gently inclined from the flat portion 6, so that the amount of liner material supplied Is reduced, and the risk of bubble generation is also reduced.

  In the resin cap of the present invention, as long as at least an annular inclined surface, a flat portion connected to the annular inclined surface, and an annular protrusion are formed, it is possible to effectively prevent the liner material from protruding after-spin and deterioration of sealing performance due to the generation of bubbles. However, as described above, by forming the annular protrusion, it is possible to reliably prevent the liner material from protruding due to after-spin and to reduce the supply amount of the liner material by forming the annular protrusion. It becomes possible. Moreover, in the preferred specific example shown in the figure, the annular ridge was formed as both inclined surfaces on the outer side surface and the inner side surface. However, if at least the outer side surface of the annular ridge is an inclined surface, it is shown in the figure. Needless to say, the same effect as that of the preferred embodiment can be obtained, and even if the side surface of the annular ridge is not formed as an inclined surface or the annular ridge itself is not present, the container in the resin cap of the present invention. Since the sealing surface with the mouth portion is an annular inclined surface, it is inferior to the preferred embodiment shown in the figure, but the sealing performance can be ensured.

(Liner material)
The liner material made of the hot melt composition used for the resin cap of the present invention is made of a thermoplastic resin or a thermoplastic resin composition having a viscosity at 180 ° C. in the range of 400 to 2000 mPa · s. It can be selected from those commercially available as melt compositions.
The hot melt composition is formed by blending a thermoplastic resin such as an olefin resin or a thermoplastic elastomer such as a styrene with a wax or a plasticizer for viscosity adjustment as necessary. Among the melt compositions, it is preferable to use a material having a viscosity at 180 ° C. in a B-type viscometer in the range of 400 to 2000 mPa · sec and a JIS A hardness in the range of 70 to 95 when forming the liner. it can. The softening point (R & B formula) is preferably in the range of 70 to 110 ° C.
Preferably, a hot melt composition based on an ethylene vinyl acetate copolymer can be used.

(Cap shell)
Since the cap shell used for the resin cap of the present invention is not heated at the time of liner molding, it is possible to use a cap shell conventionally used for a resin cap. A cap shell made of an olefin-based resin such as can be used.
In the resin cap of the present invention, since the liner surface is smooth and the coefficient of static friction is 0.10 or less, the opening torque can be reduced. Therefore, it is preferably used as a cap having a screw portion. Of course, the present invention is not limited to this, and a cap that fits into the container mouth may be used.

(Liner formation)
In the present invention, the liner material in the molten state composed of the above-described hot melt composition is applied and supplied by spin lining to the annular portion of the inner surface of the cap shell top plate that contacts the tip of the container mouth. After that, by rotating the cap shell, the liner material forms a shape along the annular inclined surface while spreading outward by centrifugal force, and the surface is smoothed, naturally cooled, and solidified. As a result, the liner corresponding to the annular inclined surface is pressure-bonded to the outer corner of the container mouth to form a liner that can ensure sealing performance.

The resin cap of the present invention is mass-produced because the amount of liner material used is reduced, and no special equipment such as a mold or an oven is required, and the productivity and economy are excellent. A general-purpose container can be suitably used.
Moreover, since the liner surface is smoothed, it has excellent sealing properties and a small opening torque, and can be suitably used particularly as a cap having a screw portion.

DESCRIPTION OF SYMBOLS 1 Cap shell, 2 Top plate part, 3 Skirt part, 5 Annular inclined surface, 6 Flat part, 7 Annular protrusion, 8 Annular protrusion, 20 Liner, 21 Nozzle, 22 Bubble, 30 Container mouth part, 32 Container mouth outer corner Department.

Claims (5)

In a resin cap having a top cap portion and a resin cap shell made of a skirt portion depending from the periphery of the top plate portion, and an annular liner made of a hot melt composition formed on the outer periphery of the inner surface of the top plate portion,
An annular inclined surface is formed at a boundary portion between the top plate inner surface and the skirt inner surface of the resin cap shell, and an annular protrusion protruding from the inner surface of the skirt portion to the inside of the cap is formed below the annular inclined surface. A flat portion connected to the annular inclined surface is formed on the inner surface of the top plate portion;
The annular inclined surface is inclined so that the axial thickness increases toward the outer diameter side of the cap,
On the inner surface of the top plate portion of the resin cap shell, an annular ridge projecting downward is formed in the cap inward of the flat portion, and at least the side surface of the annular ridge on the flat portion side is the outer diameter of the cap. It is an inclined surface where the axial thickness decreases toward
A liner made of the hot melt composition is formed above the annular protrusion and on the annular inclined surface and the flat portion;
In the closed state in which the resin cap is applied to the container mouth, the container mouth tip outer corner is in contact with a liner at a position corresponding to the annular inclined surface. Said liner, said after applying the hot melt composition in a ring to the cap shell surface, resin cap according to claim 1, wherein one formed by rotating the cap shell. The resin cap according to claim 1 or 2 , wherein the liner is formed by annularly applying the hot melt composition to the inner surface of the cap shell while rotating the cap shell. It said liner, viscosity at 180 ° C. when measured by a B-type viscometer to any one of claims 1 to 3 comprising a hot melt composition comprising a thermoplastic resin or a thermoplastic resin composition is in the range of 400～2000MPa · sec The resin cap described. The resin cap according to any one of claims 1 to 4 , wherein the liner has a JIS A hardness of 70 to 95 and a static friction coefficient of 0.10 or less.

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