JP3051946B2 - Heat sealing material for hermetically sealed containers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sealing lid material suitably used for a hermetically sealed container made of, for example, glass, metal, ceramic or ceramic.

[0002]

2. Description of the Related Art Conventionally, to seal and package powdered, liquid and viscous foods in a glass container such as a bottle, after filling the food, a metal cap is crimped on the mouth of the container, or a metal or glass container is filled. Screw the synthetic resin screw cap,
Alternatively, it was sealed by putting a crown on. Conventionally, a lid material is coated with a heat-sensitive adhesive, and the lid material is bonded to the opening of the glass container by heat sealing.

[0003]

However, there has been a problem that the cap and the crown described above are relatively difficult to open and the cost is high. When the heat-sensitive adhesive coated on the lid material is bonded to the mouth of the glass container by heat sealing, if the content of the container is a powder such as powdered milk or instant coffee, the adhesion between the container mouth and the lid material is performed. Although the adhesive strength of the part does not decrease, if the content is a liquid or viscous substance such as alcohol, juice, jam, etc., water is applied to the heat sealing adhesive between the container mouth and the lid during storage. Or jams may enter, resulting in a significant decrease in adhesive strength, and in severe cases, the lid material may peel off.

[0004] Conventionally, a method is also known in which a metal salt, a silane coupling agent, or the like is used as an anchor coat layer at the mouth of a glass container, and this layer is further coated with a heat-adhesive resin (for example, Japanese Patent Publication No. 61-1986). However, according to such a conventional method, a part of the resin of the lid material remains on the mouth of the container when the container is opened, and the appearance may be impaired. Since the resin is coated, the number of steps is increased accordingly, resulting in a problem that the productivity of the container is poor and the cost is high.

[0005] Conventionally, a heat-sealing lid material provided with a heat-sensitive adhesive layer containing a rosin in an ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVA) has already been known (for example, in the case of actual products). See JP-B-63-28137).

This conventional heat sealing material exhibits excellent sealing performance and water resistance when used for sealing small containers such as bottles mainly made of plastic, wax-coated paper, polyethylene-coated paper and the like. However, the adhesiveness is extremely poor on a porous and hydrophilic adhered surface such as the mouth of a glass container. Such a conventional heat-sealing lid material seals the mouth of the glass container. It could not be used for

[0007] An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a good adhesion to a porous and hydrophilic surface such as a mouth of a glass container or the like. In addition, even when the contents are liquids or viscous substances such as sake, juice, jam, etc., it is possible to effectively prevent water from entering the bonding interface, and to reduce the bonding strength in a water environment. Water resistance, which greatly increases the water resistance, maintains a good adhesion state for a long period of time, has excellent sealing properties, and can be easily opened with an appropriate force. An object of the present invention is to provide a heat-sealing lid material for a container for hermetically sealed packaging having both functions of adhesion and easy peeling.

[0008]

According to the present invention, in order to attain the above object, first, a heat sealing material for a container for hermetically sealed packaging according to the first invention comprises, as a main component, a butyral resin on one surface of a metal foil. Characterized in that a heat-sensitive adhesive layer containing 55 to 99 parts by weight of a heat-sensitive adhesive resin, 1 to 45 parts by weight of rosins, and 0.01 to 30 parts by weight of a higher fatty acid is provided. It is.

Next, the heat sealing material for a hermetically sealed container according to the second invention comprises 55 to 99 parts by weight of a heat-sensitive adhesive resin mainly composed of butyral resin,
45 parts by weight of the heat-sensitive adhesive layer, and the surface of the heat-sensitive adhesive layer has a higher fatty acid content of 0.01 to 10 μm.
Characterized by being coated with a thickness of

As the above-mentioned metal foil, aluminum foil is usually used, but other metal foils may be used. In the case of aluminum foil, its thickness is 5 to 200 μm, preferably 2 to 200 μm.
0 to 70 μm. When a metal foil is used as the base material of the heat sealing material, it has excellent barrier properties, and can effectively preserve contents such as desserts and cooked foods for a long period of time.

Among the constituent components of the heat-sensitive adhesive layer, first, butyral resin (PV) which is a main component of the heat-sensitive adhesive resin is used.
B) is produced by reacting polyvinyl alcohol (PVA) obtained by saponifying polyvinyl acetate (PVAc) with butyraldehyde.

Next, the rosins will be described.

In general, rosins are thermoplastic resins containing abietic acid as a main component, and include gum rosin, wood rosin and tall oil rosin.

The rosins used in the present invention include, for example, the following.

Modified rosin: hydrogenated rosin (dihydroabietic acid, tetrahydroabietic acid).

Disproportionated rosin.

Disproportionated hydrogenated rosin.

Polymerized rosin (including partially polymerized rosin).

Rosin ester: rosin alkyl ester, rosin glycol ester, rosin glycerin ester, rosin pentaerythritol ester.

Modified rosin ester: alkyl ester of modified rosin, glycol ester of modified rosin, glycerin ester of modified rosin, pentaerythritol ester of modified rosin.

Dibasic acid-modified rosin: rosin modified with maleic acid or maleic anhydride.

Dibasic acid-modified rosin ester: alkyl ester of maleic acid or maleic anhydride-modified rosin,
Glycol esters, glycerin esters, pentaerythritol esters.

The above-mentioned rosins are used alone or in combination of two or more.

The heat-sensitive adhesive layer contains 55 to 99 parts by weight, preferably 60 to 97 parts by weight of a heat-sensitive adhesive resin containing butyral resin as a main component, and 1 to 45 parts by weight, preferably 3 to 40 parts by weight of rosins. And a resin containing at least one part by weight.

Here, when the butyral resin exceeds 99 parts by weight and the rosin is less than 1 part by weight, the amount of the rosin is too small and sufficient water resistance is not imparted to the heat sealing joint. This is not preferable because the adhesiveness is lowered in a water environment.

Conversely, when the butyral resin is less than 55 parts by weight and the rosin is more than 45 parts by weight, the amount of the rosin is too large, so-called blocking occurs, which is not preferable.

As the above higher fatty acids, for example, the following are used.

That is, higher fatty acids are unsaturated and saturated higher fatty acids and include dicarboxylic acids. The oxy fatty acids (predominantly C ₁₂ or higher) are also included.

Higher fatty acids: lauric acid, stearic acid,
Oleic acid, erucic acid, etc.

The higher fatty acids may be used as a mixture of two or more kinds.

In the first aspect of the present invention, one side of the metal foil
By providing the heat-sensitive adhesive layer containing a higher fatty acid, when the higher fatty acid is present on the surface of the hermetically sealed container to be heat-bonded to the mouth, the heat-sensitive adhesive layer is formed of the heat-sensitive adhesive resin 55. ~ 99 parts by weight, preferably 60 ~ 97
Parts by weight, 1 to 45 parts by weight of rosin, preferably 3 to 4 parts by weight
0 part by weight, 0.01 to 30 parts by weight of a higher fatty acid, and preferably 1 to 10 parts by weight.

In the second aspect of the present invention, 55 to 99 parts by weight, preferably 60 parts by weight of the heat-sensitive adhesive resin is provided on one side of the metal foil.
To 97 parts by weight and a heat-sensitive adhesive layer containing 1 to 45 parts by weight, preferably 3 to 40 parts by weight of rosins,
When the surface of the heat-sensitive adhesive layer is coated with a higher fatty acid, if the higher fatty acid is allowed to exist on the surface of the hermetically sealed container to be thermally bonded to the mouth, the thickness of the higher fatty acid coating layer is reduced. The thickness is 0.01 to 10 μm, preferably 0.1 to 5 μm.

In the first and second aspects of the present invention, when the content of the higher fatty acid is less than 1 part by weight and when the thickness of the coating layer of the higher fatty acid is less than 0.01 μm, the amount of the higher fatty acid is reduced. If the amount is too small, sufficient heat resistance is not imparted to the heat-sealed joint portion, and the adhesiveness is deteriorated in a water environment, which is not preferable.

Conversely, when the content of the higher fatty acid exceeds 30 parts by weight or when the thickness of the higher fatty acid coating layer exceeds 10 μm, the higher fatty acid originally has no adhesive property, and This is not preferable because the original adhesiveness of the agent layer is reduced, or the adhesive force between the heat-sensitive adhesive layer and the hermetically sealed container via the higher fatty acid coating layer is reduced.

In the first invention, when a heat-sensitive adhesive layer containing a higher fatty acid is provided on one surface of the metal foil of the cover material, the higher fatty acid bleeds on the surface of the heat-sensitive adhesive layer, and And become concentrated. In this case, it is preferable that 1% or more of the higher fatty acid be present on the surface to be heat-sealed at the mouth of the sealed packaging container, that is, on the surface of the heat-sensitive adhesive layer.

In the second invention, when the surface of the heat-sensitive adhesive layer provided on one side of the metal foil of the lid material is coated with a higher fatty acid, the surface to be heat-bonded to the mouth of the hermetically sealed packaging container. In addition, 100% of the higher fatty acid is present, and therefore, it is easier to adjust the thickness of the coating layer, that is, the amount of the higher fatty acid to be present on the surface to be heat-sealed, as compared with the case of the first invention. .

In order to provide a heat-sensitive adhesive layer on one side of a metal foil, a heat-sensitive adhesive containing or not containing a higher fatty acid as described above is processed into a film in advance, and this film is formed on one side of the metal foil, for example. Joining via an adhesive such as a polyester-isocyanate two-component reactive adhesive or extruding a melt of a heat-sensitive adhesive on one side of a metal foil using an extruder, so that these are directly joined. do it. The thickness of the heat-sensitive adhesive layer is usually 5 to 300 μm,
Preferably it is 20 to 100 μm.

In the case where the surface of the heat-sensitive adhesive layer is coated with a higher fatty acid, the coating may be performed, for example, with a brush or a roll coater.

Further, it is preferable that the heat-sensitive adhesive layer is filled with an inorganic compound in order to ensure low-temperature sealing properties and to prevent blocking during punching by a press.

Here, examples of the inorganic compound include oxides, hydroxides, carbonates and sulfates of magnesium, calcium, aluminum, titanium and silicon, or talc, clay, feldspar powder, mica, barite and the like. However, it is particularly preferable to use calcium carbonate and talc. The average particle size of these inorganic compounds is 0.1.
It is 1 to 50 μm, preferably 0.5 to 30 μm.

When the heat-sensitive adhesive layer 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 10 parts by weight, based on 100 parts by weight of the thermoplastic resin. Parts by weight.

If necessary, a resin film such as polyethylene or polypropylene may be interposed between the heat-sensitive adhesive layer and the metal foil. Thereby, the cushioning property at the time of heat sealing is improved, and corrosion of the metal foil due to contents such as dressing and mustard can be prevented.

Further, the other surface of the metal foil is usually subjected to necessary printing, and an anticorrosion coat layer is provided on the surface.

The cover made of the metal foil and the heat-sensitive adhesive layer is continuously punched and formed into a shape and size covering the mouth of the glass container.

The hermetically sealed packaging container sealed by the heat sealing material according to the present invention is made of, for example, glass, metal, ceramic or ceramic.

FIGS. 1 to 3 show a specific example of a lid material according to the present invention. First, the lid material shown in FIG. 1 has a heat-sensitive adhesive layer containing a higher fatty acid on one side of an aluminum foil (1).
(2) is provided via an adhesive layer (3), and a higher fatty acid is present on the surface of the hermetically sealed container such as a glass container to be thermally bonded to the mouth (10). The other surface of the aluminum foil (1) is provided with an anticorrosion coat layer (4).

The lid material shown in FIG. 2 is made of aluminum foil.
A heat-sensitive adhesive layer (2) is provided on one side of (1) via an adhesive layer (3), and a coating layer (5) of a higher fatty acid is applied to the surface of the heat-sensitive adhesive layer (2). As a result, the higher fatty acid is present on the surface of the glass container to be thermally bonded to the mouth (10). The other surface of the aluminum foil (1) is similarly provided with an anticorrosion coat layer (4).

The lid shown in FIG. 3 has substantially the same structure as that of the lid shown in FIG.
In order to prevent corrosion of (1), an intermediate layer (7) made of, for example, a polyethylene film is provided on one surface of the aluminum foil (1), and the intermediate layer (7) is provided with a higher fatty acid via an adhesive layer (3). Is provided with a heat-sensitive adhesive layer (2) containing, a printed layer (6) provided on the other surface of the aluminum foil (1), and a corrosion-resistant coating layer (4) provided on the surface thereof. .

[0049]

According to the heat sealing material of the present invention, the porous glass surface can be sufficiently covered by the rosin contained in the heat-sensitive adhesive.

Further, since the heat-sensitive adhesive contains or is coated with a higher fatty acid, under a water environment, a decrease in adhesive strength is small, and a good adhesive state can be maintained for a long time.

According to the heat sealing material of the present invention, the porous glass surface can be sufficiently covered with the heat-sensitive adhesive without any gap, and the higher fatty acid is present on the surface of the glass container to be thermally bonded to the mouth. As a result, wetting of water at the bonding interface is reduced, water can be prevented from entering the bonding interface, the water absorption of the heat sealing resin is suppressed, and the water resistance of the bonded portion of the heat-sensitive adhesive is large. It increases to.

[0052]

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

Examples 1 to 7 As shown in FIG. 1, an aluminum foil (1) having a thickness of 50 μm having an anticorrosion coating layer (4) on one side and a butyral resin (trade name: Sony Bond SC423, Sony Chemical Co., Ltd.) A heat-sensitive adhesive layer (2) consisting of a heat-sensitive adhesive film having a thickness of 50 μm in which various amounts of rosins and higher fatty acids are mixed with a heat-sensitive adhesive resin (manufactured by Co., Ltd.) via the adhesive layer (3) We joined and made various lid materials.

The butyral resin was uniformly dispersed and mixed with 5% by weight of calcium carbonate having an average particle size of about 1 μm.

Further, a dibasic acid-modified rosin ester (trade name: Luisol 28, manufactured by Rika Hercules Co., Ltd.) was used as the rosin, and stearic acid was used as the higher fatty acid.

The various lid materials thus obtained were punched into a predetermined shape and size corresponding to the mouth (10) of the glass container by a punch press.

Then, a glass container was filled with water at 40 ° C., and the lid was heated and pressed at the mouth of the container for 2 seconds at a temperature of 200 ° C. and a pressure of 160 kgf / piece. The lid was directly joined to the mouth (10) of the glass container to seal the container.

Then, the peel strength of the lid material immediately after heat sealing,
The peel strength of the lid member after the sealed glass container was left standing at 40 ° C. for 30 days was measured and is shown in the following table.

Embodiments 9 to 11 In these embodiments, as shown in FIG. 2, the aluminum foil (1) having a thickness of 50 μm having an anticorrosion coating layer (4) on one side and the other surface of the aluminum foil (1) described in A heat-sensitive adhesive layer (2) made of a 50-μm-thick heat-sensitive adhesive film obtained by mixing a heat-sensitive adhesive resin made of the same butyral resin as described in Nos. 7 to 7 and rosins at a predetermined ratio shown in the following table, After bonding via (3), a stearic acid solution previously diluted in a solvent is applied to the surface of the heat-sensitive adhesive layer (2) and dried at 60 ° C. for 5 minutes to form a stearic acid coating having various thicknesses. Layer (5) was formed, and various lid materials were made.

Example 12 In this example, a disproportionated hydrogenated rosin (trade name: KR) was used as the rosin instead of the dibasic acid-modified rosin ester.
-610 Arakawa Chemical Industry Co., Ltd.), except that Examples 1 to 7 were used.

Example 13 This example was carried out in the same manner as in Examples 1 to 7 except that the higher fatty acid was replaced with oleic acid.

The lids obtained in Examples 9 to 13 were subjected to a sealing and packaging test in the same manner as in Examples 1 to 8, and the results obtained are shown in the table below.

Comparative Example 1 For comparison, an adhesive layer was formed on one side of an aluminum foil (1).
Through (3), a lid member was formed by bonding a heat-sensitive adhesive layer (2) made of the same film of butyral resin alone as in Examples 1 to 8 above.

A sealing and packaging test was conducted on this lid material in Example 1.
-8 and the results obtained are shown in the table below.

[0065]

[Table 1]

As is clear from the above table, according to the lid material of the present invention, a higher fatty acid is applied to the surface of the heat-sensitive adhesive layer (2) containing rosin and to be thermally bonded to the mouth (10) of the glass container. Is included or present by coating, so even after long-term storage of the glass container filled with water in an inverted state, the adhesive strength of the lid material does not decrease, and the water resistance is good,
Very good sealing.

On the other hand, according to the lid material of the comparative example using a heat-sensitive adhesive containing no rosin and having no higher fatty acid present on the surface, when the glass container is stored in an inverted state for a long time, The material peeled off and was poor in water resistance.

[0068]

As described above, the heat-sealing material for a hermetically sealed container according to the first invention of the present invention has a heat-sensitive adhesive resin containing a butyral resin as a main component on one side of a metal foil.
Parts by weight, 1 to 45 parts by weight of rosins, and 0.
The heat-sealing lid material for a hermetically sealed container according to the second invention of the present invention comprises the above-mentioned heat-sensitive adhesive layer on one side of a metal foil. A heat-sensitive adhesive layer containing 55 to 99 parts by weight of an adhesive resin and 1 to 45 parts by weight of a rosin is provided, and the surface of the heat-sensitive adhesive layer is coated with a higher fatty acid in a thickness of 0.01 to 10 μm. In any case, according to the lid material of the present invention, a higher fatty acid is contained or coated on the surface of the heat-sensitive adhesive layer to be thermally bonded to the mouth of the glass container and containing rosins. Therefore, it has good adhesiveness to a porous and hydrophilic adherent surface such as a mouth of a glass container or the like. And even when the content is a liquid or a viscous material such as sake, juice, jam, etc., it is possible to effectively prevent water from entering the bonding interface, and the adhesive force is less reduced in a water environment. Therefore, the water resistance is greatly increased, a good adhesion state can be maintained for a long period of time, and excellent sealing properties can be obtained, and the package can be easily opened with an appropriate force, which is very convenient.

Further, according to the heat sealing material of the present invention, after filling the food as in the prior art, a metal cap is swaged at the mouth of the container, or a metal or synthetic resin screw cap is screwed. Since the crown is not covered, the opening is easy, and the sealing cost of the hermetically sealed packaging container is reduced because the cap and the crown are not used.

In addition, the resin does not remain in the container opening when the container is opened, and thus the container opening after opening has a clean appearance and can be heat-sealed at a relatively low temperature. This has the effect of reducing equipment costs and operating costs of the device, and improving the workability of filling and sealing.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view showing a specific example of the product of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing another specific example of the product of the present invention.

FIG. 3 is a partially enlarged sectional view showing still another specific example of the product of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum foil 2 Heat-sensitive adhesive layer 3 Adhesive layer 4 Anticorrosion coat layer 5 Higher fatty acid coating layer 7 Intermediate resin layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-96339 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 15/08 B65D 53/00

Claims (2)

(57) [Claims] 1. One side of a metal foil is provided with 55 to 99 parts by weight of a heat-sensitive adhesive resin containing butyral resin as a main component, and a rosin 1
A heat-sealing lid material for a container for hermetically sealed packaging, provided with a heat-sensitive adhesive layer containing -45 parts by weight and 0.01-30 parts by weight of a higher fatty acid. 2. One side of a metal foil is provided with 55 to 99 parts by weight of a heat-sensitive adhesive resin containing butyral resin as a main component, and rosin 1
To 45 parts by weight of the heat-sensitive adhesive layer, and the surface of the heat-sensitive adhesive layer has a higher fatty acid content of 0.01 to 10 μm.
A heat-sealing lid material for hermetically sealed containers, coated with a thickness of m.