JPH02139363A - Heat sealing lid material for airtight packaging container - Google Patents

Abstract

PURPOSE:To keep an adhesion even on a surface to be bonded which is porous and has hydrophilic property such as a mouth part of a glass container, etc., by making a water repellent exist on a surface to be thermal bonded to the mouth part of an airtight packaging container. CONSTITUTION:For a lid material, on one surface of an aluminum foil 1, a heat sealing layer 2, which contains a water repellent, is provided through an adhesive layer 3, and on the surface to be thermal bonded to a mouth part 10 of an airtight packaging container such as a glass container, etc., a water repellent is made to exist. On the other surface of the aluminum foil 1, a corrosion protective coating layer 4 is applied. Also, for the lid material, on the surface to be thermal bonded to the mouth part 10 of a glass container, a water repellent may be made to exist by a method wherein on one surface of the aluminum foil 1, the heat sealing layer 2 is provided through the adhesive layer 3, and on the surface of this heat sealing layer 2, a coating layer 5 of a water repellent is applied. On the other surface of the aluminum foil 1, the corrosion protective coating layer 4 is applied in the same manner.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a heat-sealable lid material for a sealed packaging container.

Conventional technology Conventionally, in order to hermetically package powdered, liquid, or viscous foods in glass containers such as bottles, a metal cap is caulked to the mouth of the container after the food is filled, or a metal or synthetic resin cap is used. It was sealed by tightening the screw camp or by covering it with a crown. Conventionally, a lid material has been coated with a thermoadhesive resin, and this lid material has been bonded to the mouth of a glass container by heat sealing.

Problems to be Solved by the Invention However, the above-mentioned caps and crowns have the problem of being relatively difficult to open and high cost.Also, it is difficult to open the caps and crowns. When adhering by heat sealing, if the contents of the container are powder such as powdered milk or instant coffee, there will be no decrease in the adhesive strength between the container opening and the lid, but if the contents are, for example, alcohol, In the case of liquids or viscous substances such as juices and jams, water may enter the heat-sealed adhesive between the container opening and the lid during storage, significantly reducing the adhesive strength.
In severe cases, there was a problem that the lid material would peel off.

In particular, when directly thermally bonding a lid to the mouth of a glass container, the surface of the mouth of the glass container is porous;
Due to its relatively weak polarity and poor adhesion, it has recently been developed to use a carboxyl-modified saponified ethylene-vinyl acetate copolymer with improved adhesion as a heat-adhesive resin for lid materials. (For example, JP-A-60-17804
(See Publication No. 2). Such thermoadhesive resins certainly have excellent thermal adhesion properties in a very short period of time and at relatively low temperatures, and also have moderate adhesive strength that satisfies the requirements for easy opening. However, if water enters the bonded area after heat sealing, there is a problem in that the adhesion is significantly reduced and the lid material is easily peeled off from the bonded interface.

By the way, it has already been known to directly coat the mouth of a glass container with a silane coupling agent as a sealing material (for example, see Japanese Patent Publication No. 8273/1983). The work of coating the sealant is extremely troublesome, and the surface of the opening of the glass container is porous and uneven, making it difficult to apply the sealant uniformly. Therefore, if the amount of sealing material applied is not sufficient, it will be difficult to achieve a uniform seal due to the unevenness of the opening, variations in parallelism, etc., and if the amount applied is too large,
There was a problem of high cost.

Furthermore, a method is already known in which a metal salt, a silane coupling agent, etc. are used as an anchor coat layer on the opening of a glass container, and this layer is further coated with a thermoadhesive resin (for example, Japanese Patent Publication No. 81-9181) However, with this conventional method, when the container is opened, some of the resin from the lid material may remain at the mouth of the container, damaging the appearance, and the mouth of the container must be coated with thermoplastic resin in advance. Therefore, the number of steps increases accordingly,
There were problems in that the productivity of the container was poor and the cost was high.

An object of the present invention is to solve the problems of the prior art described above, and to provide good adhesion even to porous and hydrophilic adhesive parts such as the mouth of glass containers, and to provide a solution to the problems of the prior art. Even when the object is a liquid or viscous substance such as alcohol, juice, or jam, it is possible to reliably prevent water from entering the heat-sealed adhesive area, and the water absorption of the heat-sealing resin is suppressed, so that heat The water resistance of the adhesive part of the sealing material has been significantly increased, so there is little loss of adhesive strength in a water environment, and a good adhesive state can be maintained for a long period of time. Sealed packaging with excellent sealing performance. We are trying to provide lidding materials for containers.

Means for Solving the Problems In order to achieve the above object, the lid material for a sealed packaging container according to the present invention has a water repellent agent present on the surface to be thermally bonded to the mouth of the sealed packaging container. It is characterized by the fact that

Here, there are two ways to make the water repellent agent exist on the surface of the lid material to be thermally bonded.

(1) First of all, by providing a heat sealing material layer containing a water repellent on one side of the metal foil that serves as the base material of the lid material, the surface to be thermally bonded to the mouth of the sealed packaging container is , when a water repellent is present.

(II) Second, a heat sealing material layer is provided on one side of the metal foil, and by coating the surface of this heat sealing material layer with a water repellent, it can be thermally bonded to the mouth of the sealed packaging container. When a water repellent agent is made to exist on the surface to be used.

In the above, the metal foil that is the base material of the lid material is usually aluminum foil, but other metal foils may be used. In the case of aluminum foil, its thickness is 5-200/
Iff, preferably 20-60.

As the heat sealing material, any commonly used heat sealing material can be used.

Specifically, as a heat sealing material, polyethylene, a copolymer of ethylene and vinyl acetate, a copolymer of ethylene and an unsaturated carboxylic acid, or a saponified product of an ethylene-vinyl acetate copolymer and a carboxyl group-containing inorganic material are used. Modified products obtained by graft polymerization of saturated compounds, ionomers, water-dispersed polyolefins, mixtures of water-dispersed polyolefins and water-soluble epoxy resins, polyesters, modified polypropylene, polyvinyl chloride, polyvinyl butyral, polymethacrylic esters, and polyacrylic acids At least one thermoplastic synthetic resin selected from the group consisting of esters is used.

Among these resins, ethylene-vinyl acetate and ethylene-vinyl acetate have excellent thermal adhesion properties in a short time and at relatively low temperatures to the porous and relatively weakly polar mouth surface of glass containers. Modified products obtained by graft polymerizing a carboxyl group-containing unsaturated compound to a saponified polymer (see, for example, JP-A-80-178042), and ionomers (see, for example, JP-A-81-54587).
It is preferable to use

Here, the former carboxyl modified product of saponified ethylene-vinyl acetate copolymer is, for example, as follows.

That is, melt index 1-300g/10
(according to ASTM 1238-65T) and an ethylene content of 50 to 97% by weight, preferably 6
0 to 82% by weight of ethylene-vinyl acetate copolymer is saponified to give a hydroxyl equivalent of 100 to 3000 g/1 equivalent,
Preferably, it is obtained by preparing a saponified product in an amount of 200 to 1000 g/1 equivalent, and then graft polymerizing a carboxylic acid group-containing unsaturated compound to this saponified product.

Here, examples of the carboxylic acid group-containing unsaturated compound include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, and citraconic acid. The obtained graft polymer, that is, the carboxyl modified product of the saponified ethylene-vinyl acetate copolymer, has a corresponding ff of 150,000 g/1 equivalent or less, preferably 1,000 to 30,000 g/1 equivalent as a whole.

The latter ionomer is composed of a monoolefin-unsaturated carboxylic acid copolymer resin or a metal salt thereof.

Here, the monoolefin-unsaturated carboxylic acid copolymer resin includes an α-monoolefin such as ethylene, propylene, 1-butene, isobutyne, 4-methyl-1-pentene, 1-hexene, and 1-heptene; α such as acrylic acid, methacrylic acid, methacrylic acid, crotonic acid,
It is based on a resin obtained by copolymerizing β-unsaturated carboxylic acid, and typical examples include ethylene-acrylic acid copolymer resin and ethylene-methacrylic acid copolymer resin. It will be done. The molecular weight of such a copolymer resin is 1,000 to 200,000, and the unsaturated carboxylic acid content in the copolymer resin is 1 to 30% by weight, preferably 2 to 20% by weight.

Examples of metal salts of monoolefin-unsaturated carboxylic acid copolymer resins include alkali metal ions such as sodium and potassium, or alkaline earth salts such as zinc, magnesium, and calcium. Examples include ionically crosslinked resins, ie, ionomer resins, obtained by neutralization with similar metal ions. The degree of neutralization by metal ions is, for example, 0.5 to 40%. In particular, it is preferable to use an ionomer resin made of a zinc salt of an ethylene-methacrylic acid copolymer resin. The carboxylic acid content of the ionomer resin is 5-18%, and the degree of ionization is several %-9096.

Further, the heat sealing material layer is preferably filled with an inorganic compound in order to ensure low-temperature sealability and to prevent blocking during punching by press.

Here, examples of inorganic compounds include oxides, hydroxides, carbonates, and sulfates of magnesium, calcium, aluminum, titanium, and silicon, talc, clay, feldspar powder, mica, pallite, etc.
In particular, it is preferable to use calcium carbonate and talc. The average particle size of the inorganic compound is 0.1 to 504. Preferably it is 0.5 to 30 tm.

When the heat sealing material contains an inorganic compound, the amount of the inorganic compound is 30 parts by weight or less, usually 0.1 to 20 parts by weight, preferably 1 to 1□0 per 100 parts by weight of the thermoplastic resin.
Parts by weight are mixed.

Further, as the above-mentioned water repellent, for example, the following can be used.

(i) Fatty acid amide: stearic acid amide, bisstearic acid amide, palmitic acid amide, oleic acid amide, erucic acid amide, etc.

Alkylene bis fatty acid amides: methylene bis stearamide, ethylene bis stearamide.

(Order) Higher fatty acids and their salts, that is, unsaturated and saturated higher fatty acids and their salts, including dicarboxylic acids and their salts. Also included are oquin fatty acids (mainly 01□ or more).

Higher fatty acids nilauric acid, stearic acid, oleic acid,
such as erucic acid.

Salt of higher fatty acid: Al1, Ca, Mg of the above higher fatty acid
5Zn, Ba, Na.

Salts such as K.

(fit) Edible oils, olive oil, rapeseed oil, sesame oil, corn oil, etc.

Edible oil contains unsaturated fatty acids, triglycerides, etc.

(iv) Fatty acid ester fatty acid lower alcohol ester: butyl stearate, etc.

Fatty acid polyhydric alcohol esters: hydrogenated castor oil, etc.

Fatty acid polyglycol esters: ethylene glycol monostearate, etc.

(V) Fatty alcohols: cetyl alcohol, stearyl alcohol, etc.

(νl) Polyhydric alcohol: polyglycol, polyglycerol, etc.

(vii) Fatty acid chromium complex compound nistearate chromic chloride, etc.

Verf, ro, monocarboxylic complexes: vinyl perfluoric acid ester, chromium chloride of perfluorooctanoic acid, etc.

(viii) Fluorine compounds: l, 1 dihydroberfluorooctyl acrylate, bellfluorauric acid (berfluorocarboxylic acid), vinylberfluoric acid ester, etc.

(ix) Silicone compounds: methylhydrodiene polysiloxane, dimethylgilysiloxane, etc.

(X) Alkyl ethylene urea: octadecyl ethylene urea.

(xl)・Pyridinium-fatty compound nistearic acid amide・methylpyridinium chloride, etc.

(xil) Zirconium compounds: zirconium acetate, etc.

As the water repellent, two or more of these compounds may be mixed.

When a heat sealing material layer containing a water repellent agent is provided on one side of the metal foil in (1) above, and the water repellent agent is present on the surface to be thermally bonded to the mouth of the sealed packaging container. In this case, the water repellent content of the heat sealing material layer is Ol.0.1. ~30% by weight
, preferably 0.03 to 5%.

In addition, a heat sealing material layer is provided on one side of the metal foil in (n) above, and the surface of this heat sealing material layer is coated with a water repellent, so that it can be thermally bonded to the mouth of the sealed packaging container. When a water repellent is present on the surface to be coated, the thickness of the coating layer of the water repellent is 0.01=-30IyI, preferably 0.1 to 10.9.

In the case of (1) (II) above, the water repellent content is 0.01. In both cases, the amount of water repellent agent is too small,
This is undesirable because the heat-sealed joint does not have sufficient water resistance and its adhesion decreases in a water environment.Conversely, when the water repellent content exceeds 30% by weight,
-, or when the thickness of the water repellent coating layer exceeds 30 mm, the water repellent does not inherently have adhesive properties, so the inherent adhesiveness of the heat sealing material layer decreases, or the water repellent coating layer This is not preferable because the adhesive force between the heat sealing material layer and the sealed packaging container via the agent coating layer decreases.

In addition, when a heat sealing material layer containing a water repellent agent is provided on one side of the metal foil of the lid material in (1) above, the water repellent material bleeds onto the surface of the heat sealing material layer, and the water repellent material bleeds onto the surface side. It becomes diffused and concentrated. In this case, the water repellent is applied at a concentration of 1% to the surface to be heat-sealed to the mouth of the sealed packaging container, that is, to the surface of the heat-sealing material layer.
It is preferable to make it exist at least. .

In addition, when coating a water repellent on the surface of the heat sealing material layer provided on one side of the metal foil of the lid material in (n) above, the surface to be thermally bonded to the mouth of the sealed packaging container is coated with a water repellent. 10 liquid medicines
Therefore, it is easier to adjust the thickness of the coating layer, that is, the amount of water repellent present on the surface to be heat sealed, compared to the case of CI).

To provide a heat sealing material layer on one side of the metal foil, a heat sealing material containing or not containing a water repellent as described above is processed into a film in advance, and this film is coated on one side of the metal foil with, for example, polyester. The metal foil can be bonded using an adhesive such as a two-component reactive adhesive, or it can be directly bonded by extruding a molten heat sealing material onto one side of the metal foil using an extruder. Bye.

The thickness of the heat sealant layer is usually 20 to 100J7.

Further, when coating the surface of the heat sealing material layer with a water repellent agent, it may be applied by, for example, brush coating or a roll coater.

Note that, if necessary, a resin film such as polyethylene or polypropylene may be interposed between the heat sealing material layer and the metal foil. This improves cushioning properties during heat sealing and prevents corrosion of the metal foil due to contents such as dressing and mustard.

Note that the other side of the metal foil is usually subjected to necessary printing, and furthermore, an anticorrosive coating layer is provided on this surface. A lid made of metal foil and a heat sealing material layer is continuously punched and formed into a shape and size that covers the mouth of a glass container.

The hermetically sealed packaging container sealed by the heat-sealable lid according to the present invention is made of, for example, glass, metal, ceramic, or earthenware.

1 to 3 show specific examples of the lid material according to the present invention. First, the lid material shown in Fig. 1 has a heat sealing material layer (2) containing a water repellent agent interposed on one side of an aluminum foil (1) via an adhesive layer (3), and is used for sealed packaging of glass containers, etc. A water repellent agent is present on the surface to be thermally bonded to the mouth (10) of the container. Aluminum foil (1)
An anti-corrosion coating layer (4) is applied to the other surface.

In addition, the lid material shown in Fig. 2 has a heat sealing material layer (2) provided on one side of the aluminum foil (I) via an adhesive layer (3), and a heat sealing material layer (2) is provided on the surface of this heat sealing material layer (2). By applying the water repellent coating layer (5), the opening of the glass container (
10) A water repellent agent is present on the surface to be thermally bonded.

The other side of the aluminum foil (1) is similarly coated with an anticorrosive coating layer (4).

Furthermore, the lid material shown in FIG. 3 has almost the same structure as the lid material shown in FIG. An intermediate layer (7) made of a film is provided, a heat sealing material layer (2) containing a water repellent agent is provided to this intermediate layer (7) via an adhesive layer (3), and an aluminum foil (1) is provided. A printed layer (6) is provided on the other surface, and an anticorrosive coating layer (4) is further provided on that surface.

According to the heat-sealing lid material of the present invention, since a water repellent is present in the area that is to be thermally bonded to the opening (10) of the sealed packaging container, there is little decrease in adhesive strength in a water environment. ,
It is possible to maintain a good adhesive state for a long period of time and has excellent sealing properties, which is thought to be due to the reasons mentioned above.

That is, for example, the heat sealing material applied to the lid of a glass container contains -OH groups and -CO because the upper surface of the mouth of the glass container is porous, has relatively weak polarity, and has poor adhesive properties.
Resins containing many functional groups such as OH groups, such as carboxyl modified products of saponified ethylene-vinyl acetate copolymers in which 10Hi or -COOH groups are introduced into monoolefins,
and ionomer resins are used to improve adhesion, but even when such resins are used, the heat sealing process time is very short, so the functional groups in the heat sealing resin are not bonded to the glass. It is thought that the resin does not interact with the glass component on the upper surface of the mouth of the container to form hydrogen bonds, but instead adheres to the glass surface mainly due to van der Waals forces. In particular, immediately after heat sealing, the molecular segments of the heat sealing resin undergo thermal movement and their orientation is disordered, making it difficult for hydrogen bonds to occur and adhesion is primarily due to van der Waals forces. After heat sealing, the functional groups are gradually arranged on the glass surface over time, form hydrogen bonds with the silanol groups on the glass surface, and the adhesiveness gradually increases.

However, when the contents of a glass container are liquid or viscous, the glass surface at the container mouth is hydrophilic, so water molecules tend to get wet, forming a multi-molecular layer of water molecules, which makes heat sealing difficult. The van der Waals forces at the bond are weakened and the hydrogen bonds are also broken, resulting in a significant decrease in adhesive strength.

On the other hand, according to the heat-sealing lid material of the present invention, since the water repellent is present on the mouth of the glass container and the surface to be heat-sealed, water leakage at the adhesive interface is reduced, and the adhesive In addition to being able to prevent water from entering the interface, the water absorption of the heat sealing resin is suppressed, and the water resistance of the bonded portion of the heat sealing material is greatly increased.

Example Next, examples of the present invention will be described together with comparative examples.

Example 1 As shown in Fig. 1, the surface of a 50-cut aluminum foil (1) having an anti-corrosion coating layer (4) on one side was coated with a 50JIII thick aluminum foil (1) having a thickness of 50 JIII mixed with various amounts of water repellent. A heat sealing material layer (2) consisting of a heat sealing material film was bonded via an adhesive layer (3) to produce various lid materials (sample Nos. 1 to 5). Here, the heat sealing material is a modified product obtained by graft polymerizing acrylic acid to a saponified product of ethylene-vinyl acetate copolymer (registered trademark Dumilan, manufactured by Takeda Pharmaceutical Company Limited), with an average particle size of A uniformly dispersed mixture of 5% by weight of calcium carbonate of Target IIgI was used. Ethylene bisstearamide was also used as a water repellent.

The various lid materials thus obtained were punched out using a punching press into a predetermined shape and size corresponding to the opening (1o) of a glass container.

Next, the glass container was filled with water at 40°C, and the above-mentioned lid material was placed at the mouth of the container at a temperature of 200'C and a pressure of 180kg.
These lids were directly bonded to the mouth (10) of the glass container by heating and pressurizing ladder heat sealing for 2 seconds under the condition of f/piece, and the container was sealed. Then, the peel strength of the lid material immediately after heat sealing and the 71 peel strength of the lid material after the sealed glass container was left in an inverted state at 40° C. for 30 days were measured, and are shown in the table below.

Example 2 In this example, as shown in FIG. 2, the same heat sealing material layer (2 ) is provided by dry lamination, and then an ethylene bisstearamide solution diluted in CFC is applied to the surface of the heat sealing material layer (2) and dried at 60°C for 5 minutes to form various thicknesses. forming a water repellent coating layer (5);
The lid materials (sample Nos. 6 to 10) were removed.

The lid material thus obtained in 5 was subjected to a sealed packaging test in the same manner as in Example 1, and the results are shown in the table below.

Example 3 In this example, as shown in FIG. , after providing the heat sealing material layer (2) by dry lamination,
By applying a wt% oleic acid solution to the surface of the heat sealing material layer (2) and drying it at 60°C for 5 minutes, a thickness of 0.1
A water repellent coating layer (5) was formed on the sample to produce a lid material (sample No. 11).

The lid material thus obtained was subjected to a sealed packaging test in the same manner as in Example 1, and the results are shown in the table below.

Example 4 In this example, as shown in Figure 2, a special ionomer, namely a monoolefin-unsaturated carboxylic acid copolymer resin, was applied to one side of an aluminum foil (1) via an adhesive layer (3). Metal salt, trade name [Himilan 1702J
(Mitsui DuPont Polychemical Co., Ltd., melt index 14+r/10 minutes, zinc ion type) film with a thickness of 50 mm was provided by dry lamination, and then molten ethylene glycol monostearate was applied. A water repellent coating layer (5) with a thickness of approximately 0.2 mm is formed by applying the following on the surface of the heat sealing material layer (2) using a roll coating method.
, 12) was created.

The lid material thus obtained was subjected to a sealed packaging test in the same manner as in Example 1.

Comparative Example For comparison, a heat sealing material layer (2), which is the same as in Example 1 above but does not contain a water repellent agent, was dried on one side of the aluminum foil (1) via an adhesive layer (3). It was installed by laminating.

The lid material thus obtained was subjected to a sealing coloring test in the same manner as in Example 1, and the results are shown in the table below.

(Hereinafter, blank space) As is clear from the above table, according to the lid material of the present invention,
Since water repellent is present on the four sides that should be thermally bonded to the mouth (10) of the glass container, the adhesive strength of the lid material decreases even after a glass container filled with water is stored upside down for a long time. It has good water resistance and excellent sealing performance.

On the other hand, according to the comparative lid material that uses a heat sealing material that does not use a water repellent, if the glass container is stored upside down for a long time, the lid material peels off and has poor water resistance. there were.

Effects of the Invention As described above, the heat-sealing lid material according to the present invention has a water repellent present on the surface to be thermally bonded to the mouth of a sealed packaging container, and is suitable for use in the mouth of glass containers, etc. It has good adhesion even to porous and hydrophilic surfaces, such as alcohol, juice, jam, etc. The presence of the water repellent agent reduces water leakage in the heat-sealed bonded area, reliably prevents water from entering the heat-sealed bonded area, and suppresses the water absorption of the heat-sealing resin, making the heat-sealing material The water resistance of the bonded portion is significantly increased, the adhesive strength is less likely to decrease in a water environment, a good bonding state can be maintained for a long period of time, and the sealing performance is extremely excellent.

[Brief explanation of the drawing]

Fig. 1 is a partially enlarged cross-sectional view showing a specific example of the product of the present invention;
The figure is a partially enlarged sectional view showing yet another specific example, and FIG. 3 is a partially enlarged sectional view showing yet another specific example. (1)... Aluminum foil, (2)... Heat sealing material layer, (3)... Adhesive layer, (4) (7)... Anti-corrosion coating layer, (5)... Repellent Water agent coating layer, (8)・
...Printing layer. Patent applicant: Takeda Pharmaceutical Co., Ltd. Figure 1 Figure 2

Claims (3)

[Claims] (1) A heat-sealable lid material for a sealed packaging container, characterized in that a water repellent agent is present on the surface to be thermally bonded to the mouth of the sealed packaging container. (2) A claim in which a heat sealing material layer containing a water repellent agent is provided on one side of the metal foil, so that the water repellent agent is present on the surface to be thermally bonded to the mouth of the sealed packaging container. The heat-sealing lid material according to item 1. (3) A heat sealing material layer is provided on one side of the metal foil, and the surface of this heat sealing material layer is coated with a water repellent, so that the surface to be thermally bonded to the mouth of the sealed packaging container is The heat-sealable lid material according to claim 1, wherein a water repellent is present.