JP2005193965A - Lid for container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lid for a container with a liner especially suitable for a bottle made of aluminum. <P>SOLUTION: The lid for the container is constituted by forming the liner from a composition comprising (i) 95-65 wt.% polyethylene obtained by using a metallocene polymerization catalyst, with an n-decane soluble content of 0-3 wt.%, a density of 0.88-0.95 g/cc, a melt flow index (190°C and 2.16 kg) of 1-50 g/10 min, and (ii) 5-35 wt.% thermoplastic elastomer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a container lid for a glass bottle or a metal can container in the shape of a bottle, and in particular, the contents are subjected to a large internal pressure like a carbonated beverage, and after the contents are filled and sealed, heat sterilization and heat shrink labels of the containers The present invention relates to a sealing lid having a heat-resistant sealing property suitable for an aluminum bottle-shaped can container that is subjected to heat treatment such as heat pasting.

  Many beverages such as carbonated beverages are put on the market in various types of containers such as so-called PET bottles and pull-top metal cans. Of these, a lid-shaped container with a lid is increasing in demand because it can be used intermittently by the user, and the material of the container is also diverse. The lid (hereinafter sometimes referred to as a cap) of a bottle-shaped container with a lid (hereinafter also referred to as a cap) is composed of a hard cap body and a liner disposed therein. Usually, a plastic liner such as polyethylene is used.

  For example, Patent Document 1 discloses a cap using a liner made of a composition of polyolefin and ethylene / propylene copolymer rubber, which is mainly used for aseptic filling without heat treatment, and is a carbonated beverage. However, the application of heat treatment after filling and sealing is not considered, and there is actually no performance for this application, and there is a drawback that leakage occurs.

Patent Document 2 discloses an example in which a liner made of a composition containing low density polyethylene (LDPE), ethylene / propylene copolymer rubber (EPR) and a lubricant is attached to the crown.
Although it is a carbonated drink and the use of heat treatment is described there, a glass bottle is used as a container in the sealing operation by the crown. The glass bottle can apply a heavy load, which makes it possible to sufficiently compress the liner and to ensure sealing.
Japanese Patent Laid-Open No. 2-191166 EP 0 646 158 B

  In recent years, aluminum bottles have become widely used because of their excellent quality retention, adhesion characteristics such as heat-shrink labels, high-class feeling, and easy deformation and low capacity after use. Yes. These metal bottles are sealed by a so-called roll-on operation, but it is extremely difficult to secure the seal by compressing and deforming the liner with a large load like a crown stopper. This is because the mouth portion, the can body portion and the like are deformed due to the ease of deformation of the material used. Even in such a container, for the purpose of sealing after hot filling, since the liner is thermally softened by heat, the liner is sufficiently compressed to keep the seal and the problem is reduced. However, in the case of carbonated beverages, the filling temperature is as low as 5 ° C., and at this temperature, the resin of the liner is hard and sufficient compression cannot be performed to exhibit the sealing performance of the liner, and the reverse effect is obtained. Thereafter, when the heat treatment is performed, the internal stress of the liner that is not sufficiently compressed begins to relax at once, and the internal pressure cannot be resisted, and the sealing is lost. Based on the characteristics of such carbonated beverage container filling and sealing, it is possible to obtain sufficient compression to secure the sealing by roll-on sealing operation with a lower load than in the case of glass bottles at low temperatures, and it may leak by subsequent heat treatment. In addition, there is a demand for development of a liner having excellent sealing properties against impact and deformation applied to the lid after sealing.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, particularly when a roll-on operation is performed by filling a metal bottle represented by an aluminum bottle with a liquid having a large internal pressure such as a carbonated beverage. Caps can be sealed with a load that does not cause deformation of the bottle mouth, threaded part, and can body, and the sealability is not impaired or altered by subsequent heat treatment or predicted impact. An object of the present invention is to provide a bottle cap using a liner that does not.

  The present invention is a lid for sealing the mouth of a glass bottle or a metal can container having a bottle shape, which is applied to the metal lid and the inner surface of the top plate portion by melt pressing, and is heated over the entire inner surface of the top plate. In a container lid comprising a bonded liner, the liner is obtained using (i) a metallocene polymerization catalyst, and the dissolved content of n-decane is 0 to 3 wt%, and the density is 0.88 to 0.95 g / cc, melt flow index (190 ° C., 2.16 kg) is formed from a composition containing 95 to 65 wt% of polyethylene having 1 to 50 g / 10 min and (ii) 5 to 35 wt% of thermoplastic elastomer. It is a container lid.

  The liner used in the present invention is obtained by using (i) a metallocene polymerization catalyst, and the dissolved content of n-decane is 0 to 3 wt%, the density is 0.88 to 0.95 g / cc, the melt flow index (190 ° C. 2.16 kg) is formed from a composition containing 95-65 wt% polyethylene 1-50 g / 10 min and (ii) 5-35 wt% thermoplastic elastomer. Said polyethylene can be manufactured by superposing | polymerizing ethylene and a small amount of alpha olefin as needed using a metallocene polymerization catalyst. A more preferable polyethylene is one having a dissolved content of n-decane of 0 to 2.5% and a density of 0.90 to 0.93 g / cc.

The polyethylene used in the present invention is excellent in impact resistance and compression set, has a low elastic modulus, and is excellent in melt molding processability, and is combined with a predetermined amount of a thermoplastic elastomer in the present invention. It is possible to achieve the objectives at a high level.
As the thermoplastic elastomer, an ethylene / propylene copolymer having a PP content of 15 to 35%, more preferably 20 to 30%, a dynamically crosslinked product thereof, a styrene / conjugated diene block copolymer and / or a hydrogenated product thereof. Is preferably used.

  The blending ratio of the polyethylene of (i) is 95 to 65%, preferably 90 to 70%, and the thermoplastic elastomer of (ii) is 5 to 35%, more preferably 10 to 30%. In addition to these, appropriate additives can be used in combination. For example, adding fatty acid amide dimethyl siloxane such as erucic acid amide or oleic acid amide as a lubricant and mineral oil or the like as a plasticizer often brings about favorable results.

  The liner used in the present invention is usually formed by extrusion-molding the above composition into a sheet, and a disk-shaped or ring-shaped material having a size corresponding to the metal cap to be combined is punched out and bonded to the inner surface of the cap top plate. By doing so, the cap of the present invention can be obtained. Further, the above composition can be applied directly to the inner surface of the top plate of the metal cap in a molten or softened state and fused in a liner form.

In the present invention, the cap to which the liner is attached is a metal cap, and an aluminum cap is particularly preferable.
The metal cap is formed of a cylindrical body having an integrated top plate portion, as is well known in a conventionally known roll-on operation. In the roll-on operation, a metal cap provided with a liner is attached to a metal bottle prepared in advance, and pressure is applied from above to the mouth of the bottle with a pressure block. The pressure at that time is about 90 to 105 kgf in the case of an aluminum bottle. Next, while the liner is compressed by the pressure block, a screw is formed on the cap in accordance with the screw of the bottle by the RO roller. In this way, the cap of the present invention is attached to the metal bottle.

  The cap of the present invention is suitable for use with aluminum bottles, but can also be used without problems for conventional glass bottles.

  According to the present invention, it is possible to perform a sealing operation in a roll-on operation on an easily deformable aluminum bottle without any trouble, achieve a sufficient sealing, and is excellent in economic efficiency, and further, the influence of flavor on contents. The sealing lid excellent in hygiene can be provided without giving.

  The invention will now be illustrated on the basis of examples.

Example:
The physical property test and performance test of the test resin blend were conducted.
Conforms to MFI JIS K 7210 (190 ° C, 21.18N)
Compression set compliant with JIS K 6301 (50 ° C, 70 ° C, 30 minutes)
Hardness Compliant with JIS K 7215 (Durometer D)

The test resin blend material components are as follows.
(1) Polyethylene (PE)
Me: density (SG 0.92 and 0.90) with PE produced using a metallocene polymerization catalyst, n-decalin dissolution of 0.5% or less, melt flow index 5 g / 10 min,
ZN: PE produced using Ziegler polymerization catalyst
EPR: Dynamic content of ethylene propylene copolymer with PP content of 25% SEBS: Hydrogenated product of styrene ethylene butylene styrene block copolymer Others: Lubricants, etc.

(1) Physical property test:
The resin blend material was made into a 4.5 mm thick sheet, and compression set and hardness were measured.
(2) Performance evaluation:
The resin blend material is melt extruded with an extruder and a certain amount (about 4.0 g) is hot cut and inserted into a heated aluminum 28PP cap shell, and immediately pressed with a die under cooling to form a liner material. As given a certain shape. The following tests were conducted using this as a test cap.
An aluminum can container (reseal can) (300 ml) is filled with fine carbonic acid, sealed with a test cap at a capping pressure of 105 N, immersed in hot water at 70 ° C. for 10 minutes, cooled and leaked. The presence or absence was examined. Moreover, the thing which did not generate | occur | produce a leak was investigated by the presence or absence of a leak, after making it fall invert from the height of 10 cm to the cylinder of an angle of 10 degrees.

Claims (6)

  It is a lid for sealing the mouth of a glass bottle or a bottle-shaped metal can container, which is applied to the inner surface of the metal lid and the top plate portion thereof by melt pressing and is thermally bonded over the entire inner surface of the top plate. In a container lid comprising a liner, the liner is obtained using (i) a metallocene polymerization catalyst, the dissolved amount of n-decane is 0 to 3 wt%, the density is 0.88 to 0.95 g / cc, and the melt flow A container lid characterized by being formed of a composition containing 95 to 65 wt% of polyethylene having an index (190 ° C, 2.16 kg) of 1 to 50 g / 10 min and (ii) 5 to 35 wt% of a thermoplastic elastomer .   The thermoplastic elastomer (ii) is an olefin elastomer, and an ethylene / propylene copolymer (EPR), an ethylene-butylene copolymer (EBM) having a polypropylene content of 15 to 35 wt% and / or dynamic crosslinking thereof. The container lid according to claim 1, comprising a thing.   The container lid according to claim 1, wherein the thermoplastic elastomer (ii) comprises a styrene / conjugated diene block copolymer and / or a hydrogenated product thereof.   The container lid according to any one of claims 1 to 3, wherein the liner is formed by forming the composition into a sheet shape, then punching it into a disk shape or a ring shape, and adhering to the inner surface of the lid top plate.   The container lid according to any one of claims 1 to 4, wherein the bowl-shaped metal can container is a bottle-shaped aluminum can container.   The container lid according to any one of claims 1 to 5, wherein the content of the metal can container is a sparkling beverage.