JP2000281118A - Aluminum plate for cap and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum plate for a cap and its manufacturing method in which a cap formed by an aluminum plate and a polyethylene sealing material can be adhered at a low temperature, a thin wall of the cap can be attained and a high speed production of the cap can be carried out. SOLUTION: There is provided an aluminum plate 2 used in a cap of a container which is practically applied with polyethylene sealing material being set at an inner surface side of the cap after the plate is formed into the cap shape. This aluminum plate is constituted as the aluminum plate 1 for cap in which polyethylene 3 is applied to coat over the upper-most surface layer at the inner surface side of the cap at least after its machining of the aluminum plate is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum plate for a cap of a container used for preserving foods or beverages, and more particularly to a polyethylene sealing material which is attached to the cap after the aluminum plate is processed into a cap. The present invention relates to an aluminum plate for a cap having excellent adhesiveness with a cap and a method for producing the same.

[0002]

2. Description of the Related Art Caps of containers used for preserving foods or beverages are formed by processing an aluminum plate, and a resin layer is attached to the inner surface thereof for the purpose of improving corrosion resistance. Used in For example, P
P (pill fur proof) cap and TO (tear-off) cap are degreased aluminum plates, or by applying a phosphoric acid chromate treatment or a water-soluble resin containing a zirconium compound to a coating base coat on the aluminum plate, An aluminum plate coated with an epoxy resin paint is used thereon.

[0003] A polyethylene sealant is mounted on the inner surface of the cap after the aluminum plate is formed in order to improve the sealing performance between the cap and the container. The method of mounting the polyethylene sealing material includes a method of directly embossing polyethylene on the inner surface of the cap, a method of punching a polyethylene sheet into a disc shape and mounting the inner surface of the cap, and a method of capping a polyethylene disk formed by injection molding or the like. There is known a method of mounting on the inner surface side and the like.

Further, in the case where the polyethylene sealing material is coated with an epoxy resin paint and mounted on the inner surface side of the cap by the above-mentioned method, it is necessary to provide sufficient adhesion between the polyethylene sealing material and the inner coating film. At present, the bonding operation is performed by heating both the polyethylene and the cap to a high temperature of 150 ° C. to 220 ° C.

[0005]

However, the conventional aluminum plate for a cap has the following problems. When the polyethylene sealing material and cap are heated to a high temperature of 150 ° C. to 220 ° C. as described above, and then cooled to around the normal operating temperature, the difference in the amount of heat shrinkage due to the difference in linear expansion coefficient between aluminum and polyethylene. This is one of the causes of the occurrence of defects such as abnormal dimensions due to internal stress. Therefore, in order to suppress the occurrence of such dimensional abnormalities, it is necessary to increase the thickness of the aluminum plate to some extent to overcome the internal stress that causes deformation, which is one of the factors that hinder the thinning of the cap. It was also.

Similarly, when high-temperature heat is applied to aluminum, the aluminum is softened and its strength is reduced. Therefore, it is necessary to secure a certain plate thickness in order to secure the rigidity of the cap, which is one of the causes of preventing the thinning of the cap.

Further, in the sealing material mounting step, at least the adhesive surface of the polyethylene sealing material is heated and melted, and then cooled to a temperature lower than the melting point and solidified. Here, a resin having a low melting point such as polyethylene (generally having a melting point of 80 ° C to 140 ° C)
When heating to a high temperature such as 150 ° C. to 220 ° C., it takes a long time to cool and solidify the polyethylene, so that the cycle time of the mounting process becomes too long, which hinders an increase in production speed. It was one.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and enables a cap formed from an aluminum plate and a polyethylene sealing material to be mounted at a low temperature, a thin cap to be achieved, and a cap production speed to be reduced. It is an object of the present invention to provide an aluminum plate for a cap and a method for manufacturing the same, which enable high-speed processing.

[0009]

As a result of intensive studies to solve the above-mentioned problems, the present invention has made it possible to bond a polyethylene sealing material and a cap without heating to a high temperature as in the prior art. To invent an aluminum plate for a cap. That is, the gist configuration of the present invention is an aluminum plate used for a cap of a container which is used after being molded into a cap and having a polyethylene sealing material attached to an inner surface thereof, at least one of the surfaces of the aluminum plate. An aluminum plate for a cap in which the outermost surface layer corresponding to the inner surface side of the processed cap was coated with polyethylene.

[0010] With this configuration, when the cap aluminum plate is formed into a cap, the outermost surface layer on the inner surface side of the cap is already covered with a polyethylene layer. Therefore, when the polyethylene sealing material is mounted on the inner surface side of the cap, the basic chemical composition is the same, so that the chemical affinity between the inner surface side of the cap and the polyethylene sealing material is high, and the low temperature of 80 to 140 ° C. Even so, the polyethylene sealing material can be adhered.

Further, the aluminum plate is formed as a cap aluminum plate by coating the outermost surface layers on both sides with polyethylene. With this configuration, when the aluminum plate is processed into the cap by drawing or the like, the operation can be performed without specifying the processing surface.

In the case of manufacturing an aluminum plate for a cap used for a cap of a container which is used after being formed into a cap and having a polyethylene sealing material attached to the inner surface thereof, the outermost surface layer of the aluminum plate And a step of performing a coating process for coating the outermost surface layer of the aluminum plate subjected to the surface pretreatment with polyethylene.

[0013] With such a configuration, the outermost surface layer of the aluminum plate is subjected to a surface pre-treatment, such as degreasing, or a surface pre-treatment, such as roughening, in advance (or a degreasing treatment or the like). Both for rough surface treatment). Therefore, cleaning the outermost surface layer of the aluminum plate,
Alternatively, the adhesion between the aluminum plate and the polyethylene to be coated can be enhanced by increasing the contact area with the polyethylene to be coated.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. FIG. 1 is a cross-sectional view showing the configuration of an aluminum plate for a cap, FIGS. 2A and 2B are side views showing a manufacturing process of the aluminum plate for a cap, and FIGS.
FIG. 4 is a side view showing a step of forming an adhesive test piece of an aluminum plate for a cap, and FIG.
FIG. 5 is a perspective view showing a peeling test, FIG. 5 is a side view showing a step of coating an aluminum plate with polyethylene, and FIG.
FIG. 7 is a principle diagram showing a state in which an aluminum plate coated with polyethylene is pressed and formed into a cap, and FIG. 7 is a principle diagram showing a state in which a polyethylene sealing material is attached to the cap.

As shown in FIG. 1, an aluminum plate 1 for a cap provided by the present invention comprises an aluminum plate 2 and a polyethylene 3 coated on the aluminum plate 2. The aluminum plate 2 is made of aluminum or an aluminum alloy, and is not particularly limited as long as it is used as a cap of a container. Is desirable.

For example, processing characteristics are required for the purpose of the cap, and pure aluminum, aluminum-manganese, aluminum-magnesium alloys, etc., which have been conventionally used for caps, are more preferably used. . The thickness of the sheet is not particularly limited. However, as a result of taking into account the performance of the cap and the future reduction in thickness, the sheet thickness is 0.15 mm to 0.30 m.
m aluminum plate is preferably used.

The polyethylene 3 is desirably a polyethylene which exhibits an adhesive property at a low temperature in view of the gist of the present invention.
Therefore, polyethylene having a low melting point and 140 ° C. or less can be suitably used. There is no particular limitation on properties other than the melting point. Specifically, copolymerization, chemical modification, polymer blend,
In the case of pure polyethylene without a polymer alloy, all grades of resin can be used. On the other hand, in the case of polyethylene that has been modified such as copolymerization, for example, those that have been modified to lower the melting point, such as a vinyl acetate copolymer, can be suitably used, but such as a vinyl alcohol copolymer, Those modified so as to have a melting point of 140 ° C. or higher can be used, but are not suitable for the purpose of the present invention.

Further, the aluminum plate 1 is defined to cover the outermost surface layer on the inner surface side of the cap with polyethylene after processing, but the intermediate layer between the aluminum layer and the polyethylene layer is not particularly limited. Not (see FIG. 1). However, adhesion between the polyethylene layer and the aluminum layer is required.

Accordingly, it is desirable that the surface of the aluminum plate coated with polyethylene is subjected to the following surface treatment for improving the adhesiveness, alone or in combination. Surface of aluminum plate degreased, surface of aluminum plate treated with phosphoric acid chromate, surface of aluminum plate treated with coating type chromate, and coating undercoating of water-soluble resin containing zirconium compound are provided. Aluminum plate surface, anodized aluminum plate surface, aluminum plate surface roughened by chemical etching or electrolytic etching,
The surface of aluminum plate roughened by brush polishing or shot blasting, the surface of aluminum plate coated with an organic adhesive layer, the surface of aluminum plate coated with coupling material, the surface of aluminum plate coated with corona discharge, and flame treatment And the like on the surface of an aluminum plate.

The method of laminating the polyethylene 3 to be coated on the aluminum plate 1 (coating process) is not limited, and various methods can be applied. That is, a method in which a polyethylene film is bonded to a pre-heated aluminum coil or aluminum cutting plate by pressing the polyethylene film with a roll,
A method in which a polyethylene pellet is heated and melted by an extruder, then extruded into a film shape on an aluminum plate and bonded by pressing with a roll, or, as shown in FIG. 2, a polyethylene film is laminated on an aluminum plate and hot pressed. Appropriate hand casting includes a method of bonding by heating and pressing. In the lamination method shown in FIG. 2, it is convenient to arrange the Teflon film 11 so that the polyethylene 3 does not adhere to the surface of the press machine 10 during processing.

Further, for the purpose of the present invention, as shown in FIG. 1, the surface condition of the aluminum plate 1 which is the outer surface of the cap after the aluminum plate 1 is pressed is not limited at all.

[0022]

EXAMPLE As shown in FIG. 3, assuming the inner surface side of the cap, an aluminum plate 1 for a cap having the above configuration was prepared as an example. Then, an aluminum plate 9 coated with polyethylene 8 assuming a polyethylene sealing material 4 was bonded to the coated surface of the aluminum plate 1 for caps of the example while changing the bonding temperature, and the effect of the bonding temperature on the adhesion was investigated. . As comparative examples, an aluminum plate (not shown) having an outermost surface coated with an epoxy resin, and an aluminum plate (not shown) having an outermost surface coated with polyester were prepared. Then, an aluminum plate 9 coated on the coated surface with polyethylene 8 assuming a polyethylene sealing material 4
(See FIG. 3) were bonded while changing the bonding temperature, and the effect of the bonding temperature on the bonding properties was investigated.

Next, specific configurations of the embodiment and the comparative example will be described. In the tests performed in Examples and Comparative Examples having the above-described configurations, aluminum-manganese alloy plates (AA) having a plate thickness of 0.23 mm were used as the aluminum plates 2 and 9 (the same applies to Comparative Examples).
3105-H34), subjected to alkaline degreasing, phosphoric acid chromate treatment, and the chromium adhesion amount was 20 mg.
/ M ² to 30 mg / m ² was used as a base material.

As shown in FIG. 3, in the aluminum plate 2 of the embodiment, a high-density polyethylene film having a thickness of 20 μm (melting point: 120 ° C., a corona treatment on an adhesive surface) is laminated as a polyethylene 3 on the aluminum plate of the base material. , 125
After heating and pressing for 1 minute with a hot press heated to ℃,
It was taken out from the hot press, immediately immersed in water and cooled.

The epoxy resin coating material of the comparative example is
An epoxy phenolic paint was applied to the aluminum plate of the base material so as to have a thickness of 5 μm, and baked for 10 minutes in a heating drier heated to 200 ° C. And the coating material of polyester 3, which is the other comparative material,
A 20 μm-thick polyethylene terephthalate (PET) film (melting point: 255 ° C.,
After applying a corona treatment on the adhesive surface and heating and pressing for 1 minute with a hot press heated to 260 ° C. (see FIG. 2), the product was taken out of the hot press, immediately immersed in water and cooled.

Next, an aluminum plate 9 coated with polyethylene 8 assuming a polyethylene sealing material 4 is superposed on the resin-coated aluminum plates of the prepared examples and comparative examples, and the coated surfaces are overlapped with each other while changing the temperature conditions. Bonding was performed by applying heat and pressure with a hot press to prepare an adhesion test specimen (see FIG. 3). A T-peel peel test (see FIG. 4) was performed on the prepared test piece, and the adhesiveness at the interface between a polyethylene layer assuming a polyethylene sealing material and a resin coating assuming the inner surface of the cap was investigated. The results are shown in Table 1 (for simplicity in Table 1, polyethylene is denoted by PE, epoxy resin is denoted by EP, and polyester is denoted by PET).

As shown in Table 1, in the embodiment in which the polyethylenes 3 and 8 were bonded by hot pressing, when the pressing temperature was 100 ° C., the polyethylene peeled off at the interface between the polyethylenes, and the bonding strength was 0 and the bonding was not possible. Although it was sufficient, the one bonded at a press temperature of 110 ° C. or higher showed a high value of bonding strength of 1.0 kg / 10 mm or more, and the peeling form was not peeled off at the polyethylene / polyethylene interface. The polyethylene coating itself exhibited such a strong adhesion that the cohesive failure occurred.

On the other hand, in a comparative example in which polyethylene and epoxy resin were bonded by hot pressing, as shown in Table 1, peeling was performed at the interface between polyethylene and epoxy resin at a pressing temperature of 100 ° C. to 180 ° C. When the value was 0, the adhesion was insufficient. In addition, those bonded at 190 ° C. or higher did not peel at the polyethylene / epoxy resin interface, and showed a strong adhesion in which the polyethylene coating itself was cohesively broken as a peeling form. It showed a lower value than the example.

As shown in Table 1, in the comparative example in which polyethylene and polyester were further bonded by hot pressing, when the pressing temperature was in the range of 100 ° C. to 220 ° C., all peeled off at the interface between polyethylene and polyester, and the bonding strength was 0. Adhesion resulted in poor results. From the above results, it can be seen that the bonding between polyethylenes can be performed under lower temperature conditions than the bonding between polyethylene / epoxy resin and the bonding between polyethylene / polyester.

[0030]

[Table 1]

Next, as shown in FIGS. 5 to 7, a process of forming the cap 5 by using the cap aluminum plate 1 having the above-described structure will be described as an example. Note that the same members as those in the above configuration are denoted by the same reference numerals and described.
As shown in FIG. 5, the aluminum plate 1 has a thickness of 0.2
3 mm aluminum-manganese alloy plate (AA310
5-H34), and subjected to alkali degreasing as the surface base treatment 15, and then subjected to phosphoric acid chromate treatment to adjust the amount of chromium to be 20 to 30 mg / m ² as a base material. And heating oven 16
After passing through, the polyethylene film as the polyethylene 3 is pressed by a roll, and the aluminum plate 1 is wound in a state where a coating process 17 for covering the outermost surface layers on both surfaces of the aluminum plate 1 has been performed.

As shown in FIG. 6, the cap aluminum plate 1 is sized to a predetermined size and pressed by a press forming machine 18 to form the cap 5. And FIG.
As shown in the figure, the polyethylene sealing material 4 is preferably applied to the inner surface side of the molded cap 5 by the injection molding machine 19 for 110 minutes.
The cap 5 is completed by bonding in a temperature range of 140 ° C. to 140 ° C. When the polyethylene sealing material 4 is bonded, it is sufficient that at least the bonding surfaces are heated. The provision of the polyethylene 3 on the outermost surface layer on both sides of the aluminum plate 1 is convenient because the direction of the cap 5 is not specified when the cap 5 is pressed. The outermost surface layer on one surface may be covered.

[0033]

As described above, the present invention has the following advantages. It is possible to provide an aluminum plate for a cap which enables the polyethylene sealing material and the cap to be bonded without heating to a high temperature as in the related art. When the aluminum plate for a cap obtained by the present invention is used, the difference in the amount of heat shrinkage caused by the difference in the coefficient of linear expansion is reduced, and the internal stress remaining in the cap is reduced. The ratio is reduced, which is also effective in reducing the thickness of the cap. In addition, since the innermost surface after the cap molding has the same basic chemical composition as the polyethylene sealing material, both have high chemical affinity and can be adhered even at a low temperature of 80 ° C to 140 ° C. Therefore, the cycle time for bonding the polyethylene sealing material is shortened, and the production speed can be improved. With the above effects, it is possible to improve the quality and productivity of the cap.

Furthermore, since the aluminum plate for the cap has polyethylene coated on both sides of the aluminum plate to be used, it is not necessary to specify the front and back of the cap when processing and molding the cap, which is convenient. .

When the aluminum plate is coated with a polyethylene layer, the surface of the aluminum plate is subjected to a surface base treatment so that the adhesion area between the polyethylene layer and the aluminum plate can be increased and the adhesion can be improved. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a configuration of a cap aluminum plate of the present invention.

FIG. 2 is a side view showing a manufacturing process of the aluminum plate for a cap of the present invention.

FIGS. 3 (a) and 3 (b) are side views showing a step of forming an adhesive test piece of an aluminum plate for a cap according to the present invention.

FIG. 4 is a perspective view showing a T-peel type peel test of an adhesive test piece of an aluminum plate for a cap according to the present invention.

FIG. 5 is a side view showing a step of coating the aluminum plate of the present invention with polyethylene.

FIG. 6 is a principle view showing a state where an aluminum plate for a cap according to the present invention is pressed and formed into a cap.

FIG. 7 is a principle view showing a state in which a polyethylene sealing material is mounted on a cap made of an aluminum plate for a cap according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum plate for caps 2 Aluminum plate 3 Polyethylene 4 Polyethylene sealing material 5 Cap 15 Surface treatment 17 Coating processing

Continued on the front page F-term (reference) 3E084 AA12 AB01 AB10 CA01 CC02 CC04 CC08 DA01 DC02 DC04 DC08 FA09 HB01 HC07 4F100 AB10A AK04B AK04C BA02 BA03 BA06 BA10B BA10C BA13 EJ172 EJ422 EJ551 EJ591 GB15 GB90 JK09 AKBA20A CA23 CA30 CA37 EA08 EB11

Claims (3)

[Claims] 1. An aluminum plate used as a cap for a container which is used after being molded into a cap and having a polyethylene sealing material attached to the inner surface thereof, wherein at least the processed cap of the surface of the aluminum plate An aluminum plate for a cap, wherein the outermost surface layer on the inner surface side is coated with polyethylene. 2. An aluminum plate used for a cap of a container which is used after being molded into a cap and having a polyethylene sealing material attached to an inner surface thereof, wherein the aluminum plate has polyethylene on its outermost surface layers on both surfaces thereof. An aluminum plate for a cap, which is coated with 3. A method for manufacturing an aluminum plate used for a cap of a container which is used after being molded into a cap and having a polyethylene sealing material attached to an inner surface thereof, wherein polyethylene is formed on the outermost surface layer of the aluminum plate. And a step of performing a coating process for coating the outermost surface layer of the aluminum plate subjected to the surface pre-treatment with polyethylene. A method for manufacturing an aluminum plate for a cap.