JPH08301314A - Cap with oxygen-gas-barrier property and method and injection-molding mold for manufacturing it - Google Patents

Abstract

PURPOSE: To provide a cap excelling in oxygen-gas-barrier property and capable of being manufactured simply and at a low cost, a method for manufacturing it, and a manufacturing mold therefor. CONSTITUTION: This cap 10 has a cap body 16 of a thermoplastic resin and a ring-shaped sheet 26 with an oxygen-gas-barrier property which is fixed tightly to the underside of the roof 18 of the cap body 16. The ring-shaped sheet 26 has specified hardness characteristics so as to be placed airtightly against the rim of the mouth of the container when the container is stoppered. By passing a projection provided at a part of a male mold through a central hole 28 of the ring-shaped sheet 26 to hold it, the cap 10 can be manufactured easily by inmold type injectioning molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cap having an oxygen gas barrier property, a method for manufacturing the cap, and an injection molding die used for manufacturing the cap.

[0002]

It is well known that oxygen gas promotes the reproduction of aerobic bacteria and bacteria in ketchup and mayonnaise. Therefore, it has been attempted to make a container for storing contents such as ketchup and mayonnaise from an oxygen gas barrier resin (Japanese Patent Laid-Open No. 55-8).
4660 publication).

In the past, however, the cap of the container was generally a molded product composed only of a resin such as polypropylene having a high oxygen gas permeability, so that the gas barrier sheet material was opened from the container opening when the container was opened. After peeling off,
There was concern that oxygen gas would enter from each part of the cap. In particular, due to the widespread use of large-sized refrigerators in recent years, there has been a strong demand for the contents to be stored for a longer period even after being opened at a refrigerating temperature.

In response to this demand, with the cap covered, oxygen gas permeation from each part of the cap is reduced,
It has been attempted to keep the contents for a long time, and various oxygen gas barrier caps have been proposed. As such an oxygen gas barrier cap, a cap in which a gas barrier film is attached to the inside of a cap top plate portion and a packing material is arranged on the outer peripheral portion of the gas barrier film (Japanese Utility Model Laid-Open No. 2-117348, Kaihei 2-1
No. 17349) is known.

[0005]

However, in the conventional cap as described above, it is necessary to apply and cure the packing material after the gas barrier film is attached.
Manufacturing is extremely laborious and the cap becomes expensive.

Further, when the packing material is provided on the outer periphery of the gas barrier film separately from the gas barrier film, the packing material is twisted and deformed by the opening / closing operation of the cap, and the gap between the end edge of the container opening and the cap top plate portion. Gaps may be formed.

Further, the gas barrier film can be placed in the cavity of the mold during the injection molding of the cap body and integrally fused with the cap body. There is also a problem that it is difficult to place and hold it in a position.

The present invention has been made for the purpose of solving the above-mentioned conventional problems.

[0009]

In order to achieve the above object, first, an oxygen gas barrier cap according to the present invention is in close contact with a cap body made of a thermoplastic resin and a back surface of a top plate portion of the cap body. And an annular sheet body having an oxygen gas barrier property fixed by, the annular sheet body,
When the container is closed, the container has a predetermined thickness, that is, a thickness of 2 so that it is airtightly contacted or elastically pressed against the edge of the mouth of the container.
JIS from 0 μm to 2000 μm and a predetermined hardness characteristic, that is, from the side which is the surface in contact with the container mouth.
It is characterized in that the durometer hardness according to -K7215 is HDD22 to HDD100.

Regarding the oxygen gas barrier property, the oxygen gas permeability is generally 200 (cm ³ / m ² · 24 h).
-Atm) is said to have the following characteristics. Foods such as ketchup and mayonnaise with minimal addition of food additives such as germicides and antioxidants are sensitive to discoloration and rot due to oxygen gas, and have an oxygen gas permeability of 200 (cm
^This is because the required condition is ³ / m ² · 24h · atm) or less. Here, the unit of oxygen gas permeability (cm ³ / m ² · 24h · atm) is JIS-K72.
16 (cm ³ / m ² / 24h / at
Synonymous with m).

The annular sheet may be composed of a resin composition having an oxygen gas barrier property. In that case, it is preferable that the resin composition has a durometer hardness according to JIS-K7215 of HDD22 to HDD100. .

The annular sheet body may be composed of a laminated body having an oxygen gas barrier property. Also in this case,
The thickness of the laminate is 20 μm to 2000 μm, and the JIS-of the laminate from the side to be in contact with the mouth of the container.
The durometer hardness according to K7215 is preferably HDD22 to HDD100.

In the resin composition having an oxygen gas barrier property or the laminate having an oxygen gas barrier property, the resin composition is constituted so that the oxygen gas permeability is 200 (cm ³ / m ² · 24 h · atm) or less. The resin and the resin composition ratio thereof are specified, and in the laminated body, the constituent layer resin and the layer thickness thereof are specified, and the durometer hardness according to JIS-K7215 of the resin composition or the laminated body is set to HDD22 to HDD100. When the cap with the annular sheet body is attached to the threaded mouth portion of the container, the mouth portion is elastically pressed after coming into contact with the annular sheet body, and thereby the sealing is achieved. Therefore, the durometer hardness according to JIS-K7215 is set. HD
D22 or HDD 100 is a necessary condition for the sealing.

There are various conceivable oxygen gas barrier resins constituting the annular sheet, but a saponified ethylene vinyl acetate copolymer (sometimes referred to simply as EVOH).
Containing a vinylidene chloride copolymer (simply PVD
C)) or aromatic polyamide.

Including EVOH means that EVOH is 50
A resin composition containing not less than wt%, and may appropriately contain additives such as processing aids and pigments for coloring,
Alternatively, it means a laminated body in which EVOH or a resin composition containing 50% by weight or more of EVOH is arranged as a layer in at least one layer constituting the laminated body. Resin composition composed of EVOH and aliphatic polyamide, resin composition composed of EVOH and styrene-ethylene butadiene block copolymer, EVOH
An example is a resin composition composed of a thermoplastic polyurethane.

Including PVDC means that 50 PVDC
A resin composition containing not less than wt%, and may appropriately contain additives such as processing aids and pigments for coloring,
Alternatively, it means a laminated body in which PVDC or a resin composition containing 50% by weight or more of PVDC is arranged as a layer in at least one layer constituting the laminated body. Examples thereof include a resin composition composed of PVDC and polyester, a resin composition composed of PVDC and thermoplastic polyurethane, and a resin composition composed of PVDC and an ethylene methyl acrylate copolymer.

Including an aromatic polyamide means a resin composition containing 50% by weight or more of an aromatic polyamide, and may appropriately contain additives such as processing aids and pigments for coloring, or , At least 1 constituting a laminate
It means a laminate in which an aromatic polyamide or a resin composition containing 50% by weight or more of an aromatic polyamide is arranged as a layer. Examples thereof include a resin composition containing an aromatic polyamide and an aliphatic polyamide, and a resin composition containing a resin composition containing an aromatic polyamide and EVOH.

In the center hole of the annular sheet body, in order to increase the thickness of the central portion of the cap top plate portion and reduce the oxygen gas permeability of the portion, the thermoplastic resin forming the cap body is formed. Should be filled.

On the other hand, the method according to the present invention for producing the oxygen gas barrier cap having the above-mentioned constitution is an injection molding method, more specifically, an in-mold (painting molding) injection molding method. And preparing an injection molding die consisting of a female die, and holding the annular sheet body on the male die by passing a protrusion provided in a predetermined portion of the male die of the die through the center hole of the annular sheet body, After that, the mold is clamped, the thermoplastic resin is injected into the cavity formed by the female mold and the male mold, and the thermoplastic resin is cooled and solidified.

The injection molding die for manufacturing the cap having the above-mentioned structure includes a female die having a concave portion, a male die inserted into the concave portion of the female die to form a cavity having a predetermined shape, and a male die. And a protrusion that is provided in a predetermined portion of the mold and that is inserted into the center hole of the annular sheet body and holds the annular sheet body.

The male mold of this mold is preferably composed of an inner core having an injection hole for injecting a thermoplastic resin and an outer core slidably attached to the outer periphery of the inner core.

[0022]

The oxygen gas barrier cap according to the present invention is
The presence of the annular sheet body having an oxygen gas barrier property, which is attached to the back surface side of the top plate portion of the cap body without any gap, prevents the oxygen gas passing through the top plate portion from entering the container.
Further, since this annular sheet body also functions as a packing, it becomes possible to block the oxygen gas which tends to enter along the outer peripheral surface of the mouth of the container.

Further, in the manufacturing method and the mold of the present invention, the annular sheet body can be surely positioned in the cavity by the protrusion provided on the male mold of the mold.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a cap 10 according to the present invention, and FIG. 2 shows the cap 10 having a threaded mouth portion 14 of a container 12 such as ketchup or mayonnaise.
It is sectional drawing which shows the state attached to FIG. The main body 16 of the cap 10 is made of a thermoplastic resin such as polypropylene by injection molding, and has a disk-shaped top plate portion 18 and a frusto-conical or substantially cylindrical skirt extending from the peripheral portion thereof. And a section 20. The inner peripheral surface of the skirt portion 20 is provided with a screw portion 22 formed so as to be screwed into the threaded opening portion 14 of the container 12 to be sealed.

An annular sheet body 26 is fixed to the back surface of the top plate portion 18, more specifically, the surface on the side where the end edge 24 of the mouth portion 14 of the container 12 abuts when the container is attached, without a gap. The annular sheet body 26 has a gas oxygen barrier property and also has an appropriate hardness or elasticity. Further, the annular sheet body 26 has an outer diameter substantially the same as the diameter of the back surface of the top plate portion 18, and a circular small central hole 28 is formed in the center portion thereof. This central hole 28
Will be described in detail below.
It is formed mainly for holding 6 in the mold. In the finished cap 10, as shown in the drawing, the cap body 16 is inserted into the center hole 28 of the annular sheet body 26.
It is preferable that the resin is filled.

The annular sheet member 26 is made of a single-layer or laminated oxygen gas barrier sheet by, for example, an automatic punching machine, and preferably has a thickness of 20 μm to 2000 μm, more preferably 100 μm to 1000 μm. .
The oxygen gas barrier property of the annular sheet body is such that the oxygen gas permeability is 200 (cm ³ / m ² · 24h · at).
m) or less.

Although there are various oxygen gas barrier sheets, the following eight types of sheets can be preferably used.

[Sheet A] Sheet A is a saponified ethylene vinyl acetate copolymer (EVOH) manufactured by Kuraray Co., Ltd. under the trade name "EVAL # EP-G156" (ethylene content 4
7 mol%, saponification degree 98%) and acid-modified styrene-ethylene-butadiene block copolymer (SEBS) manufactured by Asahi Kasei Kogyo Co., Ltd. under the trade name "TUFTEC # MX-007".
(Styrene content 30% by weight, acid value 10 mg CH ₃ ON
a / g) both raw materials are prepared, and these resins are dry-blended at a resin composition ratio of {EVOH / SEBS} = 60/40 (wt%) to prepare an extruder equipped with a kneading type Maddock type single screw. This EVOH resin composition was extruded at a kneading temperature of 210 ° C. to prepare a single-layer sheet having a thickness of 20 μm, equipped with a coat hanger type T die. The oxygen gas permeability of this sheet A at 30 ° C. and 80% RH is 48 (cm ³ / m ² · 24 h · atm).
Durometer hardness according to IS-K7215 is HDD68
Met.

The oxygen gas permeability is JIS-K712.
6 is a measuring instrument compliant with 6
It was measured using an OX-TRAN 2/20 tester manufactured by I. The same applies to the following.

[Sheet B] Acid-modified propylene-ethylene copolymer (acid-modified PP) manufactured by Mitsui Petrochemical Co., Ltd.
Product name "Admer # QF-551", and product name "MX" manufactured by Mitsubishi Gas Chemical Co., Inc. which is polycondensed from metaxylylenediamine which is an aromatic polyamide resin and adipic acid.
Both raw materials of "D6 # T600" (PA1) were prepared, and these resins were made into resin composition ratio {acid-modified PP / PA1} = 90/1.
Dry blending as 0 (% by weight), equipped with a coat hanger type T die in an extruder equipped with a kneading type dullage type single screw, and extruding at a kneading temperature of 240 ° C.,
This is a single-layer sheet having a thickness of 2000 μm. The oxygen gas permeability of this sheet B at 30 ° C. and 80% RH was 13 (cm ³ / m ² · 24 h · atm).
Durometer hardness according to IS-K7215 is HDD83
Met.

[Sheet C] Sheet C is a two-layer laminated sheet, and the first layer is an acid-modified ethylene vinyl acetate copolymer (acid-modified EVA) manufactured by Mitsui Petrochemical Co., Ltd. under the trade name "Admer #VF". -600 "and the EVOH resin composition of sheet A was used as the second layer. The acid-modified EVA and EVOH resin composition is co-extruded at a temperature of 230 ° C. by a multi-manifold type two-layer T die extruder equipped with a full flight type screw, whereby a sheet C having a thickness of 30 μm is obtained. The oxygen gas permeability of this sheet C at 30 ° C. and 80% RH is 4
2 (cm ³ / m ² · 24h · atm), and the durometer hardness according to JIS-K7215 from the first layer side is H.
It was DD65.

When the annular sheet body 26 is formed from this sheet C, the first layer of the sheet C is arranged on the side in contact with the edge 24 of the mouth 14 of the container 12.
Also in the annular sheet body 26 including the following sheets D to H, the first layer of the sheet is arranged toward the container mouth portion 14.

[Sheet D] The sheet D is a two-layer laminated sheet produced by using a multi-manifold type two-layer T-die extrusion apparatus. The first layer is a vinylidene chloride copolymer (PVDC) made by Kureha Chemical Industry Co., Ltd. under the trade name "Kureharon" (a copolymer of vinylidene chloride content 85% by weight and vinyl chloride content 15% by weight). (Including plasticizer) and ethylene methyl acrylate copolymer (EMA)
Exxon Chemical Co., Ltd. product name "OPTEMA #TC
-110 "(21% by weight of methyl acrylate content), the second layer is ethylene vinyl acetate copolymer (EV
A) which is a product of Sumitomo Chemical Co., Ltd.
# H2011 "(vinyl acetate content 15% by weight). Resin composition ratio of PVDC and EMA {PVDC
/ EMA} = 20/80 (% by weight) for dry blending, and a kneading type dullage type single screw for temperature 1
By introducing the EVA into the two-layer T die at 90 ° C. and introducing the EVA into the two-layer T die by a full flight type screw at a temperature of 220 ° C. and performing melt lamination in the two-layer T die, coextrusion is performed. Sheet D of 120 μm is obtained. The oxygen gas permeability of this sheet D at 30 ° C. and 80% RH was 90 (cm ³ / m ² · 24 h · atm), and the durometer hardness according to JIS-K7215 from the first layer side was HDD23.

[Sheet E] The sheet E is a three-layer laminated sheet, and the first layer is EVA, which is a product name “EVATATE # H2011” (vinyl acetate content 15% by weight) manufactured by Sumitomo Chemical Co., Ltd. The second layer is PVDC made by Kureha Chemical Industry Co., Ltd. under the trade name of "Kureharon" (a copolymer having a vinylidene chloride content of 85% by weight and a vinyl chloride content of 15% by weight, and containing some plasticizer). The same EVA as the first layer is used as the layer. By coextruding these resins at a temperature of 210 ° C. by a multi-manifold type three-layer T-die extruder equipped with a full flight type screw, a sheet E having a thickness of 20 μm can be obtained. The oxygen gas permeability of this sheet E at 30 ° C. and 80% RH was 16 (cm ³ / m ² · 24 h · at).
m), and the durometer hardness according to JIS-K7215 from the first layer side was HDD42.

[Sheet F] Sheet F is a four-layer laminated sheet, the first layer of which is acid-modified EVA, manufactured by Mitsui Petrochemical Co., Ltd.
The product name "Admer # VF-600" is used, and the second layer is EVOH manufactured by Kuraray Co., Ltd. and the product name "EVAL # EP-".
E105 "(ethylene content 44 mol%, degree of saponification 99
%) And EVA as an adhesive resin (ad) for the third layer
Manufactured by Sumitomo Chemical Co., Ltd., product name "EVATE # H20
11 "(vinyl acetate content 15% by weight) and an ethylene α-olefin copolymer (PE1) in the fourth layer manufactured by Sumitomo Chemical Co., Ltd. under the trade name" EXCELLEN # VL20 ".
"0" is used. A sheet F having a thickness of 80 μm is obtained by coextruding these resins at a temperature of 250 ° C. by a multi-manifold type two-layer T die extruder equipped with a full flight type screw. The oxygen gas permeability of this sheet F at 30 ° C. and 80% RH was 21 (cm ³ / m ² · 24 h · atm), and the durometer hardness according to JIS-K7215 from the first layer side was HDD95.

[Sheet G] The sheet G is a five-layer laminated sheet. The first layer is PP, a product name "Sumitomo Noblen # X-131" manufactured by Sumitomo Chemical Co., Ltd., and the second layer is ad
Made by Sumitomo Chemical Co., Ltd.
2011 "(vinyl acetate content 15% by weight) and PA1 for the third layer manufactured by Mitsubishi Gas Chemical Co., Inc. under the trade name" MXD "
6 # T600 ”, the same ad as the second layer is used for the fourth layer, and PE5 is a product name“ EXCELLEN # VL200 ”manufactured by Sumitomo Chemical Co., Ltd., which is PE1. These resins were coextruded at a temperature of 250 ° C. by a multi-manifold type two-layer T-die extruder equipped with a full flight type screw to obtain a thickness of 20.
A sheet G of 0 μm is obtained. The oxygen gas permeability of this sheet G at 30 ° C. and 80% RH was 8.6 (cm ³
/ M ² · 24h · atm), and JI from the first layer side
The durometer hardness according to S-K7215 was HDD95.

[Sheet H] The sheet H is a five-layer laminated sheet, and the first layer is PP made by Sumitomo Chemical Co., Ltd. under the trade name "Sumitomo Noblen # X-131", and the second layer is ad
Made by Sumitomo Chemical Co., Ltd.
2011 "(vinyl acetate content 15% by weight) and EVOH for the third layer, manufactured by Kuraray Co., Ltd. under the trade name" EVAL # "
EP-E105 "(ethylene content 44 mol%, saponification degree 99%) is used, the same ad as the second layer is used for the fourth layer, and PE1 is used for the fifth layer, trade name" EXC "manufactured by Sumitomo Chemical Co., Ltd.
ELLEN # VL200 "is used. These resins were heated at a temperature of 25 with a multi-manifold type two-layer T-die extruder equipped with a full flight type screw.
By coextrusion at 0 ° C., a sheet H having a thickness of 200 μm is obtained. 30 ° C and 80% R of this sheet H
Oxygen gas permeability at H is 12 (cm ³ / m ² · 24
h · atm), and JIS-K721 from the first layer side.
The durometer hardness according to No. 5 was HDD98.

Next, a method of manufacturing the cap 10 having the annular sheet body 26 made of the oxygen gas barrier sheet such as the above-mentioned sheets A to H will be described.

The cap 10 of this embodiment is manufactured by an in-mold type (painting type) injection molding method. FIG.
5 shows each state of the mold 30 in the injection molding apparatus, reference numeral 32 shows a female mold and reference numeral 34 shows a male mold.

The female die 32 has a recess 38 which cooperates with the male die 34 to form a cavity 36. Further, the female die 32 can be moved forward and backward with respect to the male die 34 by a slide driving device (not shown) such as a hydraulic cylinder, so that the die 30 can be opened or clamped. . That is, the mold 30 is brought into the mold clamping state shown in FIG. 3 and the open state shown in FIG. 5 (the female mold is not shown) by the movement of the female mold 32. Here, in order to simplify the description, the male mold 34
The direction from the mold to the female mold 32 is the “front” direction, and the opposite direction is the “rear” direction.

The male mold 34 is basically composed of an inner core 40, an outer core 42 and a slide core 44.

The inner core 40 is fixed to a base (not shown) of the injection molding machine, and has a cylindrical main body 46.
And a convex portion 48 coaxially and integrally provided on the front end portion of the main body portion 46, and a flange portion 50 integrally provided on the rear end portion on the opposite side. The inner core 40 has a resin injection hole 52 for injecting a molten resin along the central axis, and a gate hole 54 is formed at the outlet thereof. This gate hole 54 preferably has a diameter of 0.4 mm
The diameter of the gate hole 54 is also increased when the top plate portion 18 of the cap body 16 is large. The inner core 40 is connected to a resin extruder (not shown) through the flange portion 50, and the molten resin is supplied to the resin injection hole 52 from the extruder.

The outer core 42 is the body portion 4 of the inner core 40.
6, a cup-shaped main body portion 56 slidably encapsulating, and a flange portion 58 integrally provided at the rear end of the main body portion 56.
And have. The main body portion 56 of the outer core 42 is a female die 3
The cavity 36 having substantially the same shape as the cap 10 can be formed by being arranged at a predetermined position in the recess 38 of the second cap 38, and the portion corresponding to the screw portion 22 of the cap 10 is provided with the male screw portion 60. ing. A through hole 62 into which the convex portion 48 of the inner core 40 is inserted is formed in the front end portion of the main body portion 56. The through hole 62 has substantially the same shape as the convex portion 48. An annular projection 66 that slightly protrudes forward is formed on the front end surface of the main body portion 56 and on the peripheral edge portion of the through hole 62. The outer diameter of the annular projection 66 is substantially the same as the diameter of the center hole 28 of the annular sheet body 26, and the annular sheet body 26 can be held. Further, although not shown, a vacuum suction hole for sucking and holding the annular sheet body 26 is formed at the front end portion of the main body portion 56. It is preferable to appropriately dispose a sintered metal plate or a slit plate through which a gas can pass in the depressurized suction hole in order not to leave a suction mark on the annular sheet body 26.

The slide core 44 slidably covers the cylindrical portion of the main body portion 56 of the outer core 42. A plurality of through holes 6 are formed in the outer peripheral portion of the flange portion 58 of the outer core 42.
8 are formed, and bolts 70 extending through these through holes 68 are screwed onto the outer peripheral portion of the slide core 44. The compression coil spring 7 is attached to the shaft of each bolt 70.
2 are installed. These compression coil springs 72
Is a flange portion 58 of the slide core 44 and the outer core 42.
And the flange portion 5 of the outer core 42.
8 is urged in a direction away from the slide core 44.

In the first stage of the cap manufacturing process, the female mold 32 of the mold 30 is separated from the male mold 34 (see FIG. 5).
State), the annular protrusion 66 of the outer core 42 of the male mold 34 is inserted into the central hole 28 of the annular sheet body 26 using an appropriate jig.
The annular sheet body 26 is arranged on the front end surface of the outer core 42 so that Center hole 2 of annular sheet body 26
Although the annular sheet body 26 is accurately positioned by the fitting of the ring 8 and the annular protrusion 66, in order to prevent the positional displacement more reliably, the pressure in the vacuum suction hole of the outer core 42 is set to a negative pressure, and the annular sheet body 26 is Hold by suction.

Next, the female mold 32 is moved toward the male mold 34 by a slide driving device (not shown) to perform mold clamping. At this time, the female die 32 first comes into contact with the slide core 44 of the male die 34, and then the slide core 44 and the outer core 42 are integrally moved by the spring force of the compression coil spring 72 so as to move to the outside. The core 42 contacts the inner core 40. Finally, the compression coil spring 72 is also compressed, and the slide core 44, the outer core 42, and the inner core 40 are integrated as shown in FIG.

In the mold clamped state shown in FIG. 3, the cavity 3 between the female mold 32 and the male mold 34 is formed by melting the thermoplastic resin constituting the cap body 16, for example, polypropylene.
Inject into 6 Immediately after this, when the slide driving device is driven to move the female die 32 forward by the thickness of the annular sheet body 26, as shown in FIG. 4, the spring force of the compression coil spring 72 causes the outer core of the male die 34 to move. 42 and the inner core 40 are separated from the female die 32 and the slide core 44. As a result, the front end surface of the outer core 42 and the protrusion 48 of the inner core 40 are
The front end face of is separated from the top plate portion 18 of the cap body 16. Further, at this time, since the annular sheet body 26 has already been fused in close contact with the back surface of the top plate portion 18 of the cap body 16, the annular sheet body 26 is also separated from the front end surface of the outer core 42. In this state, the protrusion 48 of the inner core 40 is
A small space 74 is formed immediately in front of the front end face of the cavity 3.
A part of the molten resin in 6 flows and fills a part of the space 74. Further, since the molten resin overflowing from the gate hole 54 is also filled in the space 74, the space 74 is substantially filled with the resin, and the rear end surface of the resin and the rear surface of the annular sheet body 26 are substantially the same surface.

The close contact state means that there is no gap between the surface of the annular sheet body 26 and the back surface of the top plate portion 18 of the cap body 16, and the cap is closed at the mouth of the container with a torque of 2 kg.
The state in which the annular sheet body 26 is not peeled from the back surface of the top plate portion 18 when screwed at m to add a twist and opened again.

When the resin constituting the cap body 16 is cooled and solidified, the slide driving device is driven again to move the female die 32 to the initial open state, and the slide core 44 is moved by the spring force of the compression coil spring 72. Is the outer core 42
Relative to the front, which causes the cap 10
Is forcibly pulled out partially from the male screw portion 60 of the outer core 42. FIG. 5 shows this state.

Finally, a discharge plate (not shown) equipped with a slide driving device such as a hydraulic cylinder is inserted between the cap 10 and the slide core 44, and the cap 10 is discharged from the male mold 34 to obtain the product. To obtain the cap 10.

The cap 10 thus obtained is
When screwed into the threaded opening 14 of the container 12, as shown in FIG.
It is pressed against the inner annular sheet body 26. Since the annular sheet body 26 has an oxygen gas barrier property and an appropriate hardness, the edge 24 of the mouth portion 14 of the container 12 is brought into close contact with the annular sheet body 26. As a result, the oxygen gas that penetrates along the outer peripheral surface of the container mouth portion 14 is blocked by the joint between the annular sheet body 26 and the edge 24 of the container mouth portion 14 and is prevented from entering the inside of the container. To be done.

In addition, the invasion of oxygen gas from the top plate portion 18 of the cap 10 is prevented by the oxygen gas barrier property of the annular sheet body 26 that is closely fixed to the back surface of the top plate portion 18. Although the central hole 28 of the annular sheet body 26 is provided, since the thickness of the resin of the cap body 16 is thick at this portion, the intrusion of oxygen gas is extremely small.

Here, the results of the hermeticity test conducted with the eight types of caps 10 having the annular sheet bodies 26 produced from the above sheets A to H will be described.

In this sealability test, Showa Denko's trade name “SHOAROMER # MG870-3”, which is polypropylene as the resin of the cap body 16, was used, and the thickness of the top plate portion 18 of the cap body 16 was set to 600 μm. , The outer diameter of the annular sheet body 28 is 28 mm, and the inner diameter (center hole diameter) is 5
mm. Also, a container of an oxygen gas barrier laminate having a layer of EVOH manufactured by Kuraray Co., Ltd. under the trade name "EVAL # EP-E105" (ethylene content 44 mol%, saponification degree 99%) is used, and the contents are used as the contents. Eight types of specimens were prepared by filling with mayonnaise and further attaching each cap 10 to the threaded mouth of the container with a capping torque of 2 kg · m. Separately from these, a comparative sample in which a cap consisting only of a cap body without an annular sheet body is attached to a container, and a commercially available heat seal layer is provided at the container mouth as a standard sample that is shielded from the outside air. A container heat-sealed with an aluminum foil was prepared.

In the test, first, two self-sealing rubber plates were attached to the body of the container of each sample except the standard sample, the needles of the syringes were inserted into each, and the air in the container was blown from one syringe. While extracting, nitrogen gas was introduced from the other syringe, and all the air inside the container was replaced with nitrogen gas. By this operation, the oxygen gas inside the container was brought close to zero, which is below the detection limit of the gas chromatograph.

After completion of the gas replacement, the sample was placed at a temperature of 23 ± 2 ° C.
Further, the sample was stored at a relative humidity of 50 ± 5% RH, the gas inside the container was sampled at regular time intervals, and the concentration of oxygen gas was measured by a gas chromatograph.

As a result, it was found that the oxygen gas concentration in the inner space of any container linearly increased with the number of storage days.

Also, the container 1 4 days after the start of measurement
When the oxygen invasion amount (ml) per book is obtained and the difference (oxygen invasion amount difference) from the oxygen invasion amount of the standard sample stored under the same conditions is obtained, the difference in the oxygen invasion amount of the sample constructed according to the present invention is Was also less than 1.5 ml. Particularly, regarding the sheets A, C, F and G, the difference in the amount of oxygen penetration was less than 0.5 ml.

When the difference in the amount of oxygen invading is less than 2.5 ml, the odor is sensually no offensive odor of the contents of the container is recognized, and the storability is maintained. It can be seen from the above experiment that the barrier property is extremely excellent.

Incidentally, the difference in the amount of oxygen invading after 4 days of the comparative sample was 2.5 ml or more, and the container contents had an offensive odor, resulting in poor storage stability.

Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above embodiments. For example, the above-described embodiment is a screw type cap 10.
However, the present invention is also applicable to a push-type cap or the like.

Further, in the above embodiment, the annular sheet body 26
The surface on the container mouth side of the container is flush with the surface on the same side of the resin that fills the center hole 28 of the annular sheet body 26. You may take the shape which protrudes to the side.

[0064]

As described above, according to the present invention, the annular sheet member, which is attached to the back surface of the top plate of the cap body without a gap, allows the oxygen gas passing through the top plate to enter the container. Can be prevented. Also, since the annular sheet body has an appropriate hardness, in other words, an appropriate elasticity, it functions as a packing when the container is closed and prevents oxygen gas from entering from the side of the container mouth. can do. Therefore, the cap of the present invention does not require the trouble of providing a packing material and can be manufactured at low cost,
Further, the invasion of oxygen gas into the inside of the container closed by this cap is greatly reduced, and the storability of the contents of the container is dramatically improved.

Further, according to the manufacturing method of the present invention, since the annular sheet body can be integrally fixed to the cap body in a close contact state, it is possible to easily manufacture the cap that reliably exhibits the above effects. The manufacturing cost per cap is also low.

Further, by using the mold according to the present invention,
The cap can be manufactured by the injection molding method while the thin annular sheet body is held in an appropriate position in the mold, and the cap having desired characteristics can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an embodiment of a cap according to the present invention.

FIG. 2 is a cross-sectional view schematically showing a state in which the cap of FIG. 1 is attached to the mouth of a container.

FIG. 3 is a schematic cross-sectional view showing a mold for manufacturing the cap according to the present invention, and a diagram showing a mold clamped state.

FIG. 4 is a schematic cross-sectional view showing a state immediately after injecting a molten resin in the mold of FIG.

5 is a schematic cross-sectional view showing a state where the mold of FIG. 3 is opened.

[Explanation of symbols]

10 ... Cap, 12 ... Container, 14 ... Threaded mouth portion, 1
6 ... Cap body, 18 ... Top plate part, 20 ... Skirt part,
26 ... Annular sheet body, 28 ... Center hole, 30 ... Mold, 32
... female type, 34 ... male type, 36 ... cavity, 38 ... concave part,
40 ... inner core, 42 ... outer core, 44 ... slide core, 52 ... resin injection hole, 54 ... gate hole, 66 ... annular projection.

Claims (10)

[Claims] 1. An oxygen gas barrier cap to be attached to the mouth of a container, wherein the cap body is made of a thermoplastic resin, and the annular ring of oxygen gas barrier property is fixed in close contact with the back surface of the top plate of the cap body. A sheet body, wherein the annular sheet body has a thickness of 20 μm to 20 μm.
An oxygen gas barrier cap having a diameter of 00 μm and having a durometer hardness according to JIS-K7215 of HDD22 to HDD100 from the side that comes into contact with the mouth of the container. 2. The annular sheet body is made of an oxygen gas barrier resin composition, and the resin composition has a JI.
The oxygen gas barrier cap according to claim 1, wherein the durometer hardness according to S-K7215 is HDD22 to HDD100. 3. The JIS-K7215 of the laminated body, wherein the annular sheet body is composed of a laminated body having an oxygen gas barrier property, and the laminated body is from a side which comes into contact with the mouth portion of the container.
Durometer hardness according to HDD22 to HDD10
The oxygen gas barrier cap according to claim 1, wherein the cap is 0. 4. The oxygen gas barrier property according to claim 1, wherein the annular sheet body contains a saponified ethylene vinyl acetate copolymer as a resin having an oxygen gas barrier property. cap. 5. The oxygen gas barrier cap according to claim 1, wherein the annular sheet contains a vinylidene chloride-based copolymer as an oxygen gas barrier resin. 6. The oxygen gas barrier cap according to claim 1, wherein the annular sheet body contains an aromatic polyamide as a resin having an oxygen gas barrier property. 7. The oxygen gas according to claim 1, wherein the thermoplastic resin forming the cap body is filled in the center hole of the annular sheet body. Barrier cap. 8. An oxygen gas barrier cap to be attached to the mouth of a container, the cap body made of a thermoplastic resin, and the oxygen gas barrier property fixed in close contact with the back surface of the top plate of the cap body. In the method for producing an article having an annular sheet body by an injection molding method, an injection molding die including a male die and a female die is prepared, and a protrusion provided at a predetermined portion of the male die of the die has A cavity formed by the female die and the male die after the annular sheet body is arranged and held in the male die so as to be inserted into the center hole of the annular sheet body and the die is clamped. Inject the thermoplastic resin in,
A method for producing an oxygen gas barrier cap, which comprises cooling and solidifying the thermoplastic resin. 9. An oxygen gas barrier cap to be attached to a mouth of a container, the cap body made of a thermoplastic resin, and the oxygen gas barrier property fixed to a back surface of a top plate portion of the cap body in a close contact state. In an injection-molding die used in the case of producing an article including the annular sheet body by an injection molding method, a female die having a recess, and a male die inserted into the recess to form a cavity having a predetermined shape. A mold for injection molding, comprising: a protrusion that is provided in a predetermined portion of the male mold and that is inserted into a center hole of the annular sheet body and holds the annular sheet body. 10. The male die comprises an inner core having an injection hole for injecting a thermoplastic resin, and an outer core slidably attached to the outer periphery of the inner core. The injection molding mold described.