JPH07276559A - Metal container sealing film - Google Patents

Abstract

(57) [Abstract] [Purpose] High frequency welding is possible directly on the metal container, there is no need to process the metal container to increase the area of the adhesive part, and the hydrophilic contents are stored in the metal container. A strong sealing strength and sealing property can be obtained even by high-frequency welding at a low temperature and in a short time so that the material does not change, and further, the high-frequency welding layer hardly swells even if it contacts the polar solvent in the metal container. To provide a metal container sealing film suitable for storing hydrophilic contents. [Structure] At least a high-frequency welding layer is laminated on an aluminum foil layer, and the aluminum foil layer has a melting point of 100 ° C. or less and a heat of crystal fusion of 100 mJ / as the high-frequency welding layer.
mg or less and melt flow rate less than 10, ethylene content 60 to 90% by weight, α, β-unsaturated carboxylic acid or α, β-unsaturated carboxylic acid derivative content 10 to
A metal container sealing film in which 40% by weight of modified polyethylene is laminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal container sealing film, and more specifically, to seal the opening of a metal container containing a hydrophilic composition as contents by high frequency welding without deteriorating the quality of the contents. The present invention relates to a metal container sealing film comprising an aluminum foil layer as a base layer and a high-frequency welding layer laminated on the aluminum foil layer, which is capable of stably storing the hydrophilic content of the container for a long period of time.

[0002]

2. Description of the Related Art The opening of a metal container filled with hydrophilic or water-containing contents such as hand cream generally causes deterioration of quality of contents due to volatilization of lower alcohol, water and the like. In order to prevent it, it is sealed with a laminated film having an aluminum foil layer as a base layer, and as one of the sealing methods, there is a method of welding the laminated film to the opening edge of the metal container by high frequency induction heating.

In the case of sealing by the above-mentioned welding, as the laminated film, one having a high-frequency welding layer laminated on one side of an aluminum foil layer is used, and the high-frequency welding layer side of the laminated film is used as an opening edge portion of a metal container. The laminated film is welded to the opening edge through the high frequency welding layer by heating with a high frequency induction heating method in a state of being in contact with.

The high-frequency induction heating method is a method of causing a conductor (metal) placed in an alternating magnetic field to generate heat due to eddy current flow and eddy current loss due to electromagnetic induction action. Since it is preferentially generated in the portion, the welded portion is efficiently heated, and there is an advantage that a necessary amount of heat can be obtained in a short time. Therefore, the method is widely used because the influence of heat on the contents is relatively small when applied to a container filled with the contents.

Conventionally, the above-mentioned high frequency welding layer has been disclosed in JP-A-55.
A thermoplastic resin having a polar group in the molecule, such as EVA (ethylene-vinyl acetate copolymer) described in JP-A-93451, has been used. However, EVA easily undergoes a structural change at high temperature, an oxidation reaction starts at around 200 ° C, and a deacetic acid reaction remarkably occurs at around 250 ° C. Therefore, EVA is thermally decomposed even during extrusion lamination processing when producing a laminated film. It is unavoidable that odor is generated, and odor is generated due to the resulting low molecular weight compound (acetic acid). Therefore, it is not suitable for use on the inner surface of the container that is in direct contact with the contents.
Further, as the amount of polar groups in the molecule increases, the water absorbency also increases. Therefore, if high-frequency induction heating is performed in a state where the polar group in the molecule is in contact with a content containing water, hydrolysis is likely to occur, resulting in insufficient adhesive strength.

It has also been proposed to use a thermoplastic resin having a small amount of polar groups in the molecule, and in order to improve the adhesiveness of the thermoplastic resin, the adhesive portion (the opening edge portion) of the metal container is previously prepared. A method of baking and coating a thermosetting resin having a good affinity with the thermoplastic resin, or in order to stabilize the adhesive force due to the welding of the thermoplastic resin, the bead diameter at the time of the bead processing of the opening edge is increased. For example, a method of increasing the area of the adhesive portion has been performed, but in order to obtain a sufficient adhesive force, it is still necessary to perform welding at a high temperature for a long time.

Therefore, in the case where the content of the metal container is sensitive to heat, such as a hydrophilic or water-containing emulsified composition such as hand cream, the components of the content are separated or separated during the welding. May change appearance. Further, if the welding temperature is suppressed to a low level in consideration of the effect of heat on the contents, the welding will be incomplete and sufficient sealing performance will not be obtained.

Further, there is a problem that a great amount of labor and cost are required to perform processing for increasing the area of the adhesive portion on the opening edge portion of the metal container. Further, there is also a method of using a polyester-based hot melt resin or a polyamide-based hot melt resin having a low melting point and a large amount of polar groups in the molecule as the welding layer, but these resins having a high polar group content also have an affinity with polar solvents. Because of its high content, when the content is a hydrophilic substance, the polyester-based hot melt resin or polyamide-based hot melt resin swells due to contact with the polar solvent (such as water) in the metal container, and peels off. A change in composition (reduction of polar solvent) occurs.

Therefore, an object of the present invention is to enable high-frequency welding to a metal container directly, without the need for processing the metal container to increase the area of the adhesive portion, and to keep the hydrophilic property contained in the metal container. It is possible to obtain a strong seal strength and hermeticity even by high frequency welding at a low temperature and in a short time so that the content does not change, and further, the high frequency welding layer contacts the polar solvent in the metal container. However, the present invention is to provide a metal container sealing film which hardly swells (does not cause a change in composition of the contents) and is suitable for storing hydrophilic contents.

[0010]

Means for Solving the Problems As a result of intensive studies on various thermoplastic resins for use as a high frequency welding layer, the present inventors have found that the high frequency welding layer has a low melting point and a small amount of heat required for crystal melting, Furthermore, they have found that the above object can be achieved by using a thermoplastic resin having a relatively large amount of polar groups in the molecule and a high melt viscosity.

The present invention has been made on the basis of the above findings, and is formed by laminating at least a high-frequency welding layer on an aluminum foil layer, and the high-frequency welding layer is formed in the opening of a metal container containing a hydrophilic composition. In a metal container sealing film for sealing the opening by a high frequency induction heating method, a melting point of 100 ° C. or lower, a crystal fusion heat amount of 100 mJ / mg or lower and a melt flow rate of the high frequency welding layer on the aluminum foil layer. Less than 10 and ethylene content 60-90
Provided is a metal container sealing film, which comprises laminated modified polyethylene having a content of 10% to 40% by weight of α, β-unsaturated carboxylic acid or α, β-unsaturated carboxylic acid derivative.

The metal container sealing film of the present invention will be described in detail below. In the metal container sealing film of the present invention, the modified polyethylene laminated on the aluminum foil layer to form the high frequency welding layer has a melting point of 100 ° C or lower, preferably 90 ° C or lower, more preferably 80 to 60 ° C and crystallized. A heat of fusion of 100 mJ / mg or less, preferably 90
mJ / mg or less, more preferably 80 to 50 mJ / mg
Is a required physical property.

When the melting point and the heat of fusion of the crystals exceed 100 ° C. and 100 mJ / mg, respectively, the amount of heat required for melting increases, so that high-frequency high-frequency irradiation is performed for a long time for high-frequency welding. When applied to a metal container filled with contents, such high output and high frequency treatment for a long time adversely affect the contents.

Further, it is essential that the modified polyethylene has a melt flow rate of less than 10, preferably 8 or less, more preferably 6 to 1. When the melt flow rate of the above-mentioned modified polyethylene is 10 or more, the melt viscosity is low, so that the film is meandered during lamination with the aluminum foil, and the tendency becomes stronger when high-speed molding is performed, resulting in extremely low productivity.

The modified polyethylene has an ethylene content of 60 to 90% by weight, preferably 70 to 85% by weight,
The content is more preferably 75 to 82% by weight, and the content of α, β-unsaturated carboxylic acid or α, β-unsaturated carboxylic acid derivative is 10 to 40% by weight, preferably 15 to 30% by weight, more preferably 18 to It is 25% by weight. Above α,
When the content of β-unsaturated carboxylic acid or α, β-unsaturated carboxylic acid derivative is less than 10% by weight, even if the modified polyethylene is completely melted, the adhesive force with the metal becomes insufficient, and if it exceeds 40% by weight. , The affinity with polar solvent becomes high, and when the container is filled with hydrophilic contents, the modified polyethylene absorbs the polar solvent and swells, causing delamination with the aluminum foil, or the composition of the contents. Cause a change.

As the above α, β-unsaturated carboxylic acid,
Acrylic acid, methacrylic acid, maleic acid and the like can be preferably mentioned, and as the above α, β-unsaturated carboxylic acid derivative, a transition metal acrylic acid neutralized product, an alkali metal acrylate neutralized product, methyl acrylate can be mentioned. , Ethyl acrylate, glycidyl acrylate and other acrylic acid derivatives;
Transition metal methacrylate neutralized product, alkali metal methacrylate neutralized product, methyl methacrylate, ethyl methacrylate,
Methacrylic acid derivatives such as glycidyl methacrylate; maleic anhydride and the like can be preferably mentioned, and these can be used alone or as a mixture.

In the present invention, when vinyl acetate or the like is used in place of the α, β-unsaturated carboxylic acid, vinyl acetate or the like hydrolyzes during high frequency treatment to generate an acetic acid odor, or extrusion lamination with aluminum foil. At times, oxidative deterioration produces hydroxyl groups, which increases the cohesive force, which increases the melting point and heat of crystal fusion of the modified polyethylene. If it is done, adhesion will be poor.

In the modified polyethylene used in the present invention, a small amount of other components may be used in addition to the above-mentioned ethylene and α, β-unsaturated carboxylic acid. At this time, other components that can be used include propylene, butene, hexene, octene, butadiene, and the like, and the amount of the other component used is 0 to 30 relative to the whole modified polyethylene. It is preferably set to wt%.

As the modified polyethylene, it is also possible to use a resin composition in which two or more kinds of resins composed of the above components are blended. In order to prepare the modified polyethylene, it is easily obtained by copolymerizing the ethylene, the α, β-unsaturated carboxylic acid, and the above-mentioned other components, which are optionally used, by a known polymerization method. be able to. Further, as the modified polyethylene, an ethylene-acrylic acid derivative copolymer or an ethylene-methacrylic acid derivative is particularly preferably used. The modified polyethylene preferably has a weight average molecular weight of 10,000 to 1,000,000.

Further, additives such as an antistatic agent, a releasing agent and a coloring agent may be appropriately added to the modified polyethylene for use. The modified polyethylene used in the present invention shows good processability, low output within a range that does not adversely affect the hydrophilic contents stored in the metal container, and high frequency welding property to metal in high frequency treatment for a short time. Excel. Further, the metal container sealed with the metal container sealing film of the present invention in which the modified polyethylene is laminated can stably hold the hydrophilic contents stored in the metal container from the initial storage for a long period of time.

The hydrophilic contents contained in the metal container sealed by the metal container sealing film of the present invention include, for example, water, linear or branched alcohols having 1 to 3 carbon atoms, and 1 to carbon atoms. 4 linear or branched carboxylic acid, alkanolamine having 1 to 4 carbon atoms, dimethylolethane, trimethanolethane, dimethylolpropane, trimethylolpropane, ethylene glycol, propylene glycol, glycerin, sorbitol, pentaerythritol, hydroxyethyl cellulose, Polyol such as polyethylene glycol, oxycarboxylic acid such as tartaric acid and malic acid, alkali metal salt of straight or branched carboxylic acid having 1 to 30 carbon atoms, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol Surfactants such as call distearate and the like, no problem even they alone or mixtures.

Examples of the hydrophilic contents include W / O type or O / W type emulsions consisting of water, oil and a surfactant, preferably O / W type emulsions as a base. Examples thereof include O / W type emulsion compositions such as emulsions and creams. The O / W emulsion composition will be described in more detail below.

In the above O / W type emulsion composition, as the above oil contained in the base O / W type emulsion, a general oily compound can be used without particular limitation. Specific examples thereof include Beeswax, wax, carnauba wax, candelilla wax, cacao butter, olive oil, camellia oil, cottonseed oil, castor oil, tung oil, coconut oil, palm oil, rapeseed oil, soybean oil,
Lanolin, sperm whale oil, rosin, tall oil, butterfat, beef tallow, animal and vegetable oils and waxes such as squalane, monoglycerides, diglycerides, triglycerides or 2-ethylhexanoic acid, caproic acid obtained by hydrolyzing or transesterifying these oils and fats, Synthetic or natural unsaturated fatty acids having 6 to 22 carbon atoms such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and oleic acid, and further 2-ethylhexyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol , Saturated or unsaturated alcohols having 6 to 22 carbon atoms such as cetyl alcohol, palmityl alcohol, stearyl alcohol, oleyl alcohol, isostearyl alcohol, lower alcohol esters such as methyl ester of the above fatty acids, In addition, higher esters such as jojoba wax composed of higher fatty acids and higher alcohols, solid paraffin, ceresin, micriclostaline wax, petrolatum, liquid paraffin, mineral oil compounds such as silicone oil, and other paraffins having 6 or more carbon atoms. , Synthetic ester oils, synthetic polyethers and the like. These may be used alone or in combination of two or more. The oil is preferably blended in the range of 1 to 85% by weight, more preferably 20 to 85% by weight, based on the whole O / W emulsion.

The surfactant contained in the O / W type emulsion is an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant or the like which is generally used. Specific examples include the following.

Examples of the anionic activator include soaps such as sodium laurate, sodium myristate, sodium palmitate and sodium stearate, alkylbenzene sulfonates, alkylnaphthalenesulfonates, alkylsulfonates, α-olefins. Sulfonates, dialkyl sulfosuccinates, α-sulfonic acid fatty acid salts, N-methyl-N-oleyl taurine, petroleum sulfonates, alkyl sulfates, sulfated fats, polyoxyethylene alkylphenyl ether fatty acid salts, polyoxyethylene Alkyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene ether phosphate, polyoxyethylene alkylphenyl ether phosphate, naphthalene sulfonic acid formaldehyde Examples thereof include hydr condensates.

As the nonionic activator, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polystyryl ether, polyoxyethylene-polyoxypropylene glycol (including block and random), Polyoxyethylene-polyoxypropylene alkyl ether, fatty acid partial ester of polyhydric alcohol (various monoglycerides, sugar esters, sorbitan esters, etc.), polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, polyoxyethylenated castor oil, fatty acid diethanolamide , Polyoxyethylene alkylamine, triethanolamine fatty acid partial ester, trialkylamine oxide and the like.

As the above-mentioned cationic activator, primary, secondary and tertiary fatty amine salts such as monoalkylamine, dialkylamine and trialkylamine hydrochlorides, tetraalkylammonium salts and 2-alkyl-1. -Alkyl-1-hydroxyethyl imidazolinium salt, N, N
-A quaternary ammonium salt such as a dialkyl monofolinium salt, and a polyethylene polyamine fatty acid amide salt, etc. may be mentioned.

Further, as the above-mentioned amphoteric surfactant, N,
N-dimethyl-N-alkyl-N-carboxymethylammonium betaine, N, N-dialkylaminoalkylenecarboxylic acid salt, N, N-trialkyl-N-sulfoalkyleneammonium betaine, N, N-dialkyl-N, N- Examples thereof include bispolyoxyethylene ammonium sulfate ester betaine and 2-alkyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine.

In addition to these, natural surfactants such as xanthan gum, lecithin such as soybean and egg yolk may be used.

The above-mentioned surfactants may be used alone or in combination, if necessary, and are preferably used in the O.W type emulsion as a whole.
In the range of 01 to 30% by weight, more preferably 0.1 to 30% by weight.
It is mixed in the range of 10% by weight.

The water content can be appropriately selected according to the purpose of use of the O / W emulsion and the required appropriate physical properties.
It is preferably compounded in the range of 10 to 99% by weight, more preferably 15 to 80% by weight, based on the whole O / W emulsion.

If necessary, various other components may be mixed in the above O / W emulsion composition system. That is, ethylene glycol, propylene glycol, glycerin, sorbitol, polyols such as glucose, lower alcohols such as ethyl alcohol, etc., which help stabilize the system, antioxidants, preservatives, colorants, flavors, seasonings, moisturizers, Viscosity modifiers and other additives may be added within the range usually used.

The O / W emulsion composition based on the O / W emulsion described herein, such as an O / W emulsion or an O / W cream, is used in the usual sense. It is used, for example, it is stabilized by forming particles of an oily component in water with a surfactant, and the size of the particles is 0.01 μm to 100 μm, and has a particle size distribution. Emulsions are fluid at room temperature, and creams are not fluid at room temperature.

Such O / W type emulsions and O / W type creams include skin care creams, emollient lotions, moisturizing lotions, milky lotions, nourishing lotions, massage lotions and cleansings in the field of cosmetics and cosmetics. Lotion, makeup cream, vanishing cream, emollient cream, baby cream, cleansing cream,
Massage cream, hair cream, deodorant cream, shaving cream, hair remover and the like can be mentioned. In the food field, emulsified dressing such as Italian dressing and French dressing,
Mayonnaise, coffee whitener, soup, ice cream and the like.

Examples of the material of the metal container whose opening is sealed by the metal container sealing film of the present invention include aluminum, tin plate, steel and the like, and even a single layer may be used as long as the portion in contact with the metal container sealing film is metal. It may be multi-layered, and the shape of the metal container is not particularly limited.

Thus, the metal container sealing film of the present invention is formed by laminating the modified polyethylene on at least one surface of the aluminum foil layer to form a high frequency welding layer.
In addition, the metal container sealing film of the present invention may have a two-layer film structure of aluminum foil / high frequency welding resin, but an adhesive layer may be provided between the aluminum foil and the high frequency welding resin, or a film may be formed on the outside of the aluminum foil. You may provide the reinforcement layer which consists of PET etc. which improves the mechanical strength of.

The thickness of the aluminum foil layer in the metal container sealing film of the present invention is preferably 7 to 50 μm, more preferably 9 to 30 μm, and most preferably 9 to 30 μm.
It is 20 μm. The thickness of the high frequency welding layer is 5 to
It is preferably 150 μm, more preferably 5 to 8
It is 0 μm, most preferably 10 to 50 μm. Also,
Lamination of the modified polyethylene on the aluminum foil layer can be easily performed by a dry laminating method, an extrusion laminating method, or the like.

Next, an example of the metal container sealing film of the present invention will be described with reference to the drawings. Figure 1
FIG. 2 is a cross-sectional view showing an example of the metal container sealing film of the present invention, and FIG. 2 is a cross-sectional view showing how the metal container sealing film shown in FIG. 1 is welded to the opening of the metal container by the high frequency induction heating method.

The metal container sealing film of this embodiment is shown in FIG.
As shown in FIG. 1, a high-frequency welding layer 12 as a surface layer is laminated on one side of the aluminum foil layer 11 as a lower laminated film, and the metal container sealing film is applied to the opening edge portion 21 of the metal container 2 through the high-frequency welding layer 12 through The opening 21 of the metal container 2 can be sealed by welding by induction heating.

Next, a method for sealing the opening of a metal can (metal container) such as an aluminum can using the metal container sealing film of the present invention will be described. For example, as shown in FIG. The opening 21 of the can 2 is covered with the metal container sealing film 1 that is cut to a size slightly larger than the opening 21, and the high frequency induction heating device is applied to the film.

The schematic structure of the high frequency induction heating apparatus shown in FIG. 2 will be described.
A rubber plate 32 is provided on the lower surface of the coil case 31, and the metal can 2
A copper tubular coil 34 is arranged at a position almost directly above the opening edge portion 22 of the above with a copper plate 33 interposed therebetween, and a ferrite 35 is erected on one side surface of the coil 34.

In the high frequency induction heating device 3, by passing a high frequency current through the coil 34, the coil 3
4 is induced around the periphery of the metal container 4 by induction heating of the high-frequency welding layer 12 located immediately above the opening edge portion 22 of the metal-container sealing film 1, so that the metal-container sealing film 1 is interposed via the high-frequency welding layer 12. It can be welded to the opening edge 22 of the metal can 2. In the present invention, the high-frequency output that does not affect the contents is 9 kW or less, preferably 8 kW.
It is desirable that the treatment time be less than or equal to 7 kW, and more preferable that the treatment time be 0.1 to 1 second.

In the metal container sealing film of the present invention constructed as described above, the high-frequency welding layer 12 has a lower melting point, a smaller amount of heat of crystal fusion, and a smaller amount of polar groups in the molecule than conventional thermoplastic resins. Since a relatively large amount of modified polyethylene is used, a strong sealing strength and sealing performance can be obtained by high-frequency welding the metal container sealing film to the opening 21 of the metal can 2 at a temperature at which the contents are not deteriorated. You can The melting point and the heat of fusion of crystals in the present invention are measured by a differential scanning calorimeter (“DSC” manufactured by Seiko Denshi Kogyo Co., Ltd.)
-220 "is used) and the temperature is measured at a temperature rising rate of 10 ° C / min from -50 ° C to 200 ° C.

[0044]

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1 An aluminum foil layer having a thickness of 20 μm and a PET layer having a thickness of 12 μm were laminated by dry lamination to obtain a laminated film having a reinforcing layer provided on the aluminum foil layer. Then, on the aluminum foil side of this laminated film, ethylene-methyl acrylate (weight ratio 80: 2
0) having a melting point of 79 ° C. and a crystal fusion heat amount of 69 mJ /
mg, and modified polyethylene having a melt flow rate shown in [Table 1] (manufactured by Nippon Petrochemical Co., Ltd., trade name “LEX Pearl RB3240”) was laminated by extrusion lamination to form a high-frequency welding layer, with a total thickness of 55 μm. A laminated film (metal container sealing film of the present invention) was obtained (high-frequency welding layer thickness 20 μm). The obtained laminated film was fused to an opening of a metal can filled with an O / W cream having the following formulation by a high frequency induction heating method (output 7 kw) to seal the opening.

<O / W cream formulation> Oil component; Stearyl alcohol 3.0 parts by weight Olive oil 3.0 parts by weight Squalane 3.0 parts by weight Vaseline 1.0 parts by weight Cetanol 5.0 parts by weight Surfactant; Sodium polyoxyethylene lauryl ether phosphate (4EO) 2.0 parts by weight Sorbitan monostearate 2.5 parts by weight Perfume 0.1 parts by weight Preservatives, antioxidants 0.4 parts by weight Moisturizers; glycerin 15 parts by weight Part Sorbit solution (70%) 10 parts by weight Purified water 50.5 parts by weight

Example 2 An aluminum foil layer having a thickness of 20 μm and a polyethylene layer having a thickness of 15 μm were laminated by dry lamination to obtain a laminated film having a reinforcing layer provided on the aluminum foil layer. Then, on the aluminum foil side surface of this laminated film, ethylene-ethyl acrylate (weight ratio 7
5:25) with a melting point of 90 ° C. and a crystal fusion heat of 61
Modified polyethylene (trade name "N Polymer A1600" manufactured by Nippon Petrochemical Co., Ltd.) having mJ / mg and a melt flow rate shown in [Table 1] was laminated by extrusion lamination to form a high frequency welding layer, and the total thickness A 55 μm laminated film (metal container sealing film of the present invention) was obtained (high-frequency welding layer thickness 20 μm). Using the obtained laminated film, the opening of a metal can filled with O / W cream was sealed in the same manner as in Example 1.

(Example 3) Ethylene / ethyl acrylate / maleic anhydride (weight ratio: 82: 15: 3) having a melting point of 92 ° C and a heat of crystal fusion of 90 mJ / mg.
Modified polyethylene having a melt flow rate shown in [Table 1] (Sumitomo CDF, trade name "Bondain TX8030") was laminated on the surface of an aluminum foil (thickness 15 µm) by extrusion lamination to form a high frequency welding layer. A laminated film (metal container sealing film of the present invention) was obtained (high-frequency welding layer thickness 20 μm). Using the obtained laminated film, the opening of a metal can filled with O / W cream was sealed in the same manner as in Example 1.

Example 4 A modified polyethylene comprising ethylene-acrylic acid (weight ratio 88:12) having a melting point of 94 ° C., a heat of fusion of crystal of 90 mJ / mg, and a melt flow rate shown in [Table 1]. (Mitsui DuPont Polychemical Co., Ltd., trade name "Nucrel AN4221
C ”) was laminated on the surface of an aluminum foil (thickness 15 μm) by extrusion lamination to form a high frequency welding layer, and a laminated film (metal container sealing film of the present invention) was obtained (high frequency welding layer thickness 20 μm). . Using the obtained laminated film, the opening of a metal can filled with O / W cream was sealed in the same manner as in Example 1.

(Comparative Example 1) Low density polyethylene (Mitsui Petrochemical Co., Ltd., trade name "Mirason 50", melting point: 110)
° C, heat of fusion of crystal: 118 mJ / mg, [Table 1]
It has been attempted to obtain a laminated film by extruding and laminating (having a melt flow rate shown in 1) on the surface of an aluminum foil (thickness 15 μm), but there was no interlayer adhesion at all, and a laminated film could not be obtained.

(Comparative Example 2) A modified polyethylene comprising ethylene-glycidyl methacrylate (weight ratio 90:10) having a melting point of 97 ° C., a heat of crystal fusion of 101 mJ / mg, and a melt flow rate shown in [Table 1]. (Sumitomo Chemical Co., Ltd., trade name "Bond First E") was laminated on the surface of an aluminum foil (thickness: 15 μm) by extrusion lamination to form a high frequency welding layer, and a laminated film was obtained (thickness of high frequency welding layer). 20 μm). Using the obtained laminated film, the opening of a metal can filled with O / W cream was sealed in the same manner as in Example 1.

(Comparative Example 3) A modified polyethylene comprising ethylene-vinyl acetate (weight ratio 90:10) having a melting point of 90 ° C, a heat of fusion of crystal of 94 mJ / mg, and a melt flow rate shown in [Table 1]. (Mitsui DuPont Polychemical Co., Ltd., trade name "Eva Flex EV56
0 ”) was laminated on the surface of an aluminum foil (thickness 15 μm) by extrusion lamination to form a high-frequency welding layer, and a laminated film was obtained (high-frequency welding layer thickness 20 μm). Using the obtained laminated film, O /
The opening of the metal can filled with W cream was sealed.

(Comparative Example 4) Terephthalic acid-isophthalic acid-adipic acid-1,4-butanediol (43:21:
36: 100) having a melting point of 96 ° C., a heat of fusion of crystal of 25 mJ / mg, and a melt flow rate shown in [Table 1] (Asahi Kasei Co., Ltd., trade name “HARDEC A6300”) to aluminum foil (thickness). 15 μm) and laminated by extrusion lamination to obtain a laminated film (high-frequency welding layer thickness 20 μm). Using the obtained laminated film, the opening of a metal can filled with O / W cream was sealed in the same manner as in Example 1.

Next, the following evaluations were carried out on the aluminum foil laminated film and the hermetically sealed container obtained in each of the above Examples and Comparative Examples. The results are shown in [Table 1].

<Evaluation Method> Adhesiveness: A gum tape is attached to the surface of the aluminum foil laminated film in the sealed container and immersed in water. When an injection needle is shot at the position where the gum tape is attached and penetrated inside to form a hole, and air is sent into the container at a rate of 0.01 kgf / sec through the hole and air leaks out. Was used as the value of the adhesive strength. Sealability: A container obtained by welding the aluminum foil laminated film obtained in each of the above Examples and Comparative Examples by a high frequency induction heating method and sealing it in the opening of a metal can filled with O / W cream for 6 months. The weight reduction rate of the O / W cream after storage at 40 ° C. and 75% relative humidity was used as the evaluation of the sealing property. Stability: A container obtained by welding the aluminum foil laminated film obtained in each of the above Examples and Comparative Examples by a high frequency induction heating method and sealing the container in an opening of a metal can filled with O / W cream for one month. After storing at room temperature, it was opened and the state of change of the contents and the state of the inner surface of each film were observed.

[0056]

[Table 1]

[0057]

INDUSTRIAL APPLICABILITY The metal container sealing film of the present invention can be directly high-frequency welded to the metal container, and it is not necessary to process the metal container to increase the area of the adhesive portion, and the metal container can be stored in the metal container. It is possible to obtain a strong seal strength and sealing property even by high frequency welding at a low temperature and in a short time so that the hydrophilic content does not change, and the high frequency welding layer is a polar solvent in a metal container. It is a metal container-sealed film suitable for storage of hydrophilic contents, which hardly swells even when contacted with it (does not cause composition change of contents).

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a metal container sealing film of the present invention.

FIG. 2 is a cross-sectional view showing how the metal container sealing film shown in FIG. 1 is welded to an opening of a metal container by a high frequency induction heating method.

[Explanation of symbols]

 1 Metal Container Sealing Film 11 Aluminum Foil Layer 12 High Frequency Welding Layer 13 Outer Layer 2 Metal Container 21 Opening 22 Opening Edge

Claims (3)

[Claims] 1. An aluminum foil layer is laminated with at least a high-frequency welding layer, and the opening is sealed by a high-frequency induction heating method through the high-frequency welding layer in the opening of a metal container containing a hydrophilic composition. In the metal container sealing film, the aluminum foil layer has a melting point of 1 as the high frequency welding layer.
At a temperature of 00 ° C or less, a heat of fusion of crystal of 100 mJ / mg or less, a melt flow rate of less than 10, and an ethylene content of 6
0 to 90% by weight, α, β-unsaturated carboxylic acid or α, β-unsaturated carboxylic acid derivative content 10 to 40% by weight
A metal container sealing film, which is obtained by laminating the modified polyethylene as described above. 2. The metal container sealing film according to claim 1, wherein the modified polyethylene is an ethylene-acrylic acid derivative copolymer or an ethylene-methacrylic acid derivative copolymer. 3. The hydrophilic composition is an O / W emulsion composition based on an O / W emulsion consisting of water, oil and a surfactant. A metal container sealing film as described.