JP2001322666A - Metal can lid material and metal can package using the same - Google Patents

Abstract

(57) [Problem] To provide a lid material suitable for a metal can in which an upper end of a body is integrally formed in a flange shape, and a metal can package using the same. SOLUTION: A cover material 1 used for a metal can in which an upper end of a body is integrally formed in a flange shape is provided with a synthetic resin layer 3 having a cushioning property on a base material layer 2 such as aluminum foil or paper, and an acid on the outer surface thereof. A heat sealing layer 4 containing at least 50% by weight of at least one selected from a modified polypropylene resin, an acid-modified polyethylene resin, and a resin obtained by acid-modifying ethylene and propylene copolymer is provided. The package is formed by heat sealing to an inward flange provided at the opening of the metal can.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal can packaging lid for foods, beverages, pharmaceuticals, quasi-drugs, electronic and electrical parts, and other industrial materials, and a metal can packaging body using the same.

[0002]

2. Description of the Related Art Metal cans have long been used as containers for storing and transporting foods, pharmaceuticals, industrial materials, and the like. In recent years, metal cans have been replaced with cans having a simplified structure to reduce weight and cost. is there. That is, the conventional three-piece can has a can bottom,
The torso, canopy or flange are integrated by caulking such as winding, but a can consisting of only the can bottom and torso has been developed to simplify the process, and the upper end of the torso is directly flanged. And a simplified structure in which an opening packaging material is attached to the flange portion. There is a step in the flange due to the seam of the metal plate when the body is formed, and there is a drawback that moisture and oxygen flow in from the step. Further, in the above-described three-piece can, a metal lid is used as a lid material, but the lid tends to be abolished due to weight reduction and cost reduction. Especially when the contents are pharmaceuticals or powdered milk, the lid is often opened by the elderly or mother, and metal lids require labor and equipment to open, and in some cases injure your fingers. However, it is not suitable for consumers, for example, the contents may be scattered.

[0003]

As a substitute for a metal lid, a soft packaging material (laminate) using a coating type hot melt, an EVA resin, or the like.
However, when both are stored in a high-temperature atmosphere such as summertime or a low-temperature atmosphere in wintertime during the distribution stage of the product, there has been a problem that the seal strength is remarkably lowered or a leak failure occurs. Therefore, an object of the present invention is to provide a lid material suitable for a metal can in which the upper end of a trunk portion is integrally formed in a flange shape, and a package using the same.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems, in the lid material of the present invention, at least a base material layer,
A synthetic resin layer, and at least one selected from an acid-modified polypropylene resin, an acid-modified polyethylene resin, and a resin obtained by acid-modifying a copolymer of ethylene and propylene;
The structure in which the heat sealing layers containing 0% by weight or more were sequentially provided was adopted. It is preferable that the base layer is formed of at least one selected from aluminum foil, metal foil other than aluminum, biaxially stretched PET film, biaxially stretched nylon film, and paper. Further, it is preferable that the synthetic resin layer is a non-stretched molded film or a resin layer laminated by a resin extrusion method, and has a thickness of 15 to 100 μm.

[0005] The package of the present invention is obtained by heat-sealing the lid and a metal can in which the upper end of the body is integrally formed in a flange shape. It is preferable to coat at least one part of the flange portion of the metal can (a welded portion of the can body) with a resin paint (for example, a resin containing 50% or more of a polyester resin) for correcting a level difference. In addition, powdered milk can be stored as a content.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, a metal can lid 1
Is a heat seal containing at least 50% by weight of at least one selected from an acid-modified polypropylene resin, an acid-modified polyethylene resin and a resin obtained by acid-modifying a copolymer of ethylene and propylene via a synthetic resin layer 3 in a base material layer 2. The layer 4 is provided.

The base layer 2 is made of an aluminum foil (A
l), a metal foil other than aluminum, biaxially oriented polyethylene terephthalate (PET) film, biaxially oriented nylon (NY) film, at least one selected from paper, etc., having a thickness of 5 to 200 μm, preferably 10 to 8 μm.
0 μm is desirable. If the thickness is less than 5 μm, the number of pinholes increases, and the moisture-permeation resistance and the oxygen-permeation resistance may be inferior. On the other hand, if the thickness exceeds 200 μm, the cost increases and the heat sealing property deteriorates (the heat sealing time increases).
It is not desirable for such reasons. Examples of the metal foil other than the aluminum foil include a copper foil, a silver foil, a gold foil, a steel foil, a stainless steel foil, a titanium foil, a tin foil, and the like. An aluminum foil is particularly preferable in terms of cost and industrial production. Aluminum foil is made of pure aluminum (JIS 1000 series, for example, 1
N30, 1N70, etc.), Al-Mn series (3000 series, for example, 3003, 3004, etc.), Al-Mg series (5,
000 system), Al-Fe system (8000 system, for example, 80
21, 8079), and is preferably a semi-hard material or a soft material, and is preferably subjected to at least one heat treatment (usually 200 to 500 ° C.) after rolling. When paper is used for the base layer 2, coated paper, kraft paper, recycled paper, woodfree paper, pure white roll paper, imitation paper, western paper, Japanese paper, cardboard, and the like can be used.

The synthetic resin layer 3 is made of a non-stretched film or a resin layer laminated by a resin extrusion method.
Its thickness is 15-100 μm, preferably 15-50 μm
m is desirable. If the thickness is less than 15 μm, there is a possibility that a gap is formed because the thickness is insufficient to fill the step of the flange portion of the two-piece can. On the other hand, if it exceeds 100 μm, it is not desirable because the cost is increased and the thermal conductivity is inferior (heat sealing time is lengthened). Examples of the unstretched molded film include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), unstretched polypropylene (CPP), ethylene-vinyl acetate copolymer (EVA), and acid-modified LLD.
PE, acid-modified EVA, acid-modified CPP, ionomer, ethylene / acrylic acid copolymer (EAA), ethylene / methacrylic acid copolymer (EMAA), ethylene / methyl methacrylate copolymer (EMMA), ethylene / Examples include a film containing an ethyl acrylate copolymer (EEA) as a component, and a resin having the same components as those described above can be used for a resin layer laminated by a resin extrusion method. Among these, acid-modified CPP or ionomer can be preferably used.

The heat sealing layer 4 contains at least 50% by weight of at least one selected from an acid-modified polypropylene (PP) resin, an acid-modified polyethylene (PE) resin and a resin obtained by acid-modifying a copolymer of ethylene and propylene. Required to be included. For the heat sealing layer, at least one kind of, for example, EVA, EAA, EMAA, EMMA, ionomer and the like can be used in a blended state at a ratio of 50% by weight or less. Among them, especially acid-modified polypropylene and EVA
Can be preferably used. The thickness of the heat sealing layer 4 is 1 to 15 μm, preferably 2 to 8 μm. 1
If it is less than μm, sufficient adhesive strength cannot be expected, and if it exceeds 15 μm, it is not desirable because it is excessive and increases the cost and the resin residue after peeling from the can flange becomes noticeable. For lacquer type, 1 to 15 g / m ² on a dry weight after, it may be preferably 2 to 8 g / m ² coating.

A known method can be used for bonding the respective layers as necessary. For example, a dry method using an epoxy-based, polyether-based, two-component reactive polyester-based, or two-component reactive polyester-polyurethane-based adhesive or the like can be used. Lamination can be performed by a method such as lamination, wet lamination, co-extrusion, extrusion lamination, or the like. In addition, a printing layer, an anchor coat layer (AC), an outer surface protection layer, a coloring layer, (alumina, silica, aluminum, etc.) may be provided at any position as necessary.
Laminated layers and the like may be used.

As shown in FIG. 2, the metal can used in the present invention comprises a bottom plate 11 and a body (also referred to as a body plate) 12, and a flange 13 is formed inwardly around the opening of the body 12. It is desirable to be processed. The bottom plate 11 and the body 12 are integrated by caulking, crimping, welding, bonding, and the like, and the seam portion 12a of the body 12 is similarly joined by caulking, crimping, welding, bonding, etc. Is molded. Other than these, a handle or a vine may be used. Examples of the material of the metal can include, but are not limited to, steel, stainless steel, aluminum, and tin (tin-plated steel plate). Of these, tinplate is practically preferred. Although the size of the metal can is not limited, it is usually about 0.05 to 20 liters in internal volume. The flange 13 of the metal can has a step due to the seam portion 12a of the body portion 12, and in this portion, in order to prevent leakage,
It is preferable to provide a resin coating 13a containing 50% or more of a polyester resin by solid content weight.

The lid material 1 is bonded to the flange 13 formed on the metal can by heat sealing (also referred to as heat sealing) so that the lid material 1 can be hermetically sealed. The conditions for heat sealing are usually at 140 to 240 ° C. for about 0.5 to 5 seconds.
At this time, it is customary to simultaneously apply a pressure of about 10 to 200 MPa.

Although the contents are not particularly limited, foods, beverages, pharmaceuticals, quasi-drugs, electronic and electrical parts, and other industrial materials are suitable.
For example, infant formula is suitable. The package of the present invention is easy to open, has excellent barrier properties against oxygen and moisture, and has high safety and reliability because there is no foreign matter after sealing. Metal cans are recyclable and can be said to be environmentally friendly packaging.

[0014]

EXAMPLE In a drying chamber, powdered milk was put into a tin can (FIG. 2) in which the upper end of the body was integrally formed into a flange shape (flange integrated molding) as shown in FIG. 2 until about 8 minutes, and the following (1) to (1)
A cover (diameter: about 100 mm) having the configuration shown in 4) was
Heat sealing was performed with a hot plate of 50 MPa for 2 seconds to seal. Fifteen packages of each configuration were produced.
The sample was held in a 50 ° C. relative humidity of 90% and -20 ° C. constant temperature (humidity and humidity) apparatus, and the opening strength in the 45 ° direction, the pressure resistance, and the presence or absence of changes in the contents before and after 3 months were tested. The test results are shown in FIG. The opening strength is data after 3 months except for the initial stage, and indicates a value (kgf / can) peeled off at a speed of 300 mm / min in the 45 ° direction. The pressure resistance indicates the pressure (kgf / cm ² ) when the lid material bursts when an internal pressure is applied. Regarding the change of the contents, the case where there was no remarkable change was evaluated as ○, and the case where moisture absorption and discoloration occurred were evaluated as ×.

The following PET films are manufactured by Unitika Co., Ltd., aluminum foil is manufactured by Toyo Aluminum Co., Ltd., various acid-modified films are manufactured by Tocelo Co., Ltd., and other films are manufactured by Toray Co., Ltd., Toyobo Co., Ltd. and Aicello Chemical Co., Ltd. A commercially available product manufactured by KK was used. The lacquer coat is
Using various acid-modified resins and EVA resins manufactured by Mitsui Chemicals, Inc., 3 g / m ^{2 was} applied by dry weight. D indicates dry lamination, and other abbreviations are the same as those shown in the text. The number before the abbreviation indicates the thickness (μm) of each layer. [Examples] (1) 16 PET / D / 40Al / D / 30 acid-modified CPP / lacquer / acid-modified PP 100% (2) 16 PET / D / 40Al / D / 30 acid-modified CPP / lacquer / acid-modified PE 100% (3) 16 PET / D / 40 Al / D / 30 acid-modified CPP / lacquer / acid-modified PP: EVA = 7: 3 (4) 16 PET / D / 40 Al / D / 30 acid-modified CPP / lacquer / acid-modified PP: EVA = 5: 5 (5) 16 PET / D / 40Al / D / 30 CPP / lacquer
Acid-modified PP: EVA = 7: 3 (6) 16 PET / D / 40Al / D / 30 acid-modified LLDPE /
Lacquer / acid-modified PE 100% (7) 16 PET / D / 40Al / D / 30 acid-modified EVA / lacquer / acid-modified PP 100% (8) 16 PET / D / 40Al / D / 30HDPE / lacquer / acid-modified PE: EVA = 7: 3 (9) 16 PET / D / 40 Al / D / 30 LDPE / lacquer / acid-modified PE: EVA = 7: 3 (10) 16 PET / D / 40 Al / D / 30 CPP / lacquer
Acid-modified PP: EVA = 5: 5 [Comparative Example] (11) 16 PET / D / 40 Al / D / 20 biaxially stretched OPP / lacquer / acid-modified PP: EVA = 5: 5 (12) 16 PET / D / 40 Al / D / 20 biaxially stretched OPP / lacquer / acid-modified PP 100% (13) 16 PET / D / 40Al / D / 30 acid-modified CPP / lacquer / acid-modified PP: EVA = 3: 7 (14) 16 PET / D / 40Al / D / 30 acid-modified LLDPE /
Lacquer / acid-modified PE: EVA = 3: 7

[0016]

According to the present invention, as described above, by providing a specific synthetic resin layer under a base material layer, it is possible to fill a step of a flange joint of a flange integrally molded metal can at the time of heat sealing. At the same time, the distortion between the metal hot plate and the tin plate flange of the hot plate seal can be absorbed, and by using a resin containing 50% or more of acid-modified polypropylene resin or acid-modified polyethylene resin as the heat sealing layer, As a result, it is possible to obtain a package that is easy to open and has high stability over time in a high-temperature atmosphere and a low-temperature atmosphere for transportation and storage of the distributed contents.

Furthermore, there is no need to apply a special surface treatment or the like to the entire surface of the flange of the metal can integrally formed with the flange, so that a low cost, highly safe and reliable package can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a lid material of the present invention.

FIG. 2 is a perspective view showing an example of a metal can integrally formed with a flange.

FIG. 3 is a table showing test results of Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cover material 2 Base material layer 3 Synthetic resin layer 4 Heat sealing layer 11 Bottom plate 12 Body 12a Seam 13 Flange 13a Resin coating

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masafumi Yamamoto 530-4 Tsuchiyama, Hiraoka-cho, Kakogawa-shi, Hyogo (72) Inventor Hiroshi Kubo 192-1-201, Tsuretori-cho, Isesaki-shi, Gunma (72) Inventor Yuji Hoshino Tokyo 2-3-6 Kyobashi, Chuo-ku, Tokyo Meiji Dairies Co., Ltd. (72) Inventor Kimitaka Kuroki 2-3-6 Kyobashi, Chuo-ku, Tokyo Meiji Dairies Co., Ltd. (72) Inventor Koji Iwata Central Tokyo 2-3-2 Kyobashi, Ward Meiji Dairy Products Co., Ltd. (72) Inventor Kiyoji Kawamata 2-275 Yoshino-cho, Omiya-shi, Saitama Nippon Seikan Co., Ltd. F-term (reference) 3E061 AA16 BA02 BB01 3E084 AA02 AA12 AA22 AB07 BA01 BA06 BA07 BA08 BA09 CA01 CB03 CC01 CC02 CC03 CC07 CC08 EA01 EC01 EC02 EC03 EC08 EC09 FA09 FD13 GB08 HA01 HB01 HC08 HD01 KA15 LA01 LA07

Claims (6)

[Claims] 1. A heat containing at least 50% by weight of at least one selected from the group consisting of an acid-modified polypropylene resin, an acid-modified polyethylene resin, and a resin obtained by acid-modifying a copolymer of ethylene and propylene. A metal can lid material provided with a sealing layer in order. 2. The metal can for a metal can according to claim 1, wherein the base layer is made of at least one selected from aluminum foil, metal foil other than aluminum, biaxially stretched PET film, biaxially stretched nylon film, and paper. Lid material. 3. The synthetic resin layer comprises a non-stretched molded film or a resin layer laminated by a resin extrusion method,
The cover material for a metal can according to claim 1, wherein the thickness is 15 to 100 μm. 4. A package obtained by heat-sealing the lid material according to claim 1, and a metal can having an upper end of a body integrally formed in a flange shape. 5. The package according to claim 4, wherein at least a part of the flange portion of the metal can in which the upper end of the body is integrally formed in a flange shape is coated with a resin containing 50% or more of a polyester resin. 6. The composition according to claim 4, wherein the content is powdered milk.
A package according to item 1.