JPH067929U - Cap seal material - Google Patents

Abstract

(57) [Summary] [Purpose] When laminating a biaxially stretched thermoplastic synthetic resin film to reduce the thickness of aluminum foil and maintain its strength, curling properties that facilitate embossing and prevention of deformation after punching, springs Development of cap sealing material with low backing property. [Structure] A cap sealing material in which a synthetic resin biaxially stretched film (1) having a thickness of 12 to 50 μm and containing voids inside, an aluminum foil (2) having a thickness of 7 to 20 μm, and an adhesive layer (3) are laminated.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention mainly relates to a cap sealing material which is covered on an opening of a container such as a bottle made of a synthetic resin and adhered to the opening by a heat seal in a hermetically sealed state, and which is then molded.

In this specification, the term aluminum is used to include aluminum and aluminum alloys.

[0003]

[Prior art]

 For example, when the cap sealant is attached to a container such as a bottle filled with powder, liquid, fluid food, toiletry, or chemicals, and the package is hermetically sealed, the cap sealant having a thermal adhesive layer should be attached to the container opening. Conventionally, a method of bonding by heat sealing has been used. As such a cap sealant, thermal bonding for fusion bonding mainly composed of an ethylene copolymer and wax is performed on one surface of an aluminum foil which is a conventional base material through an adhesion mediation layer made of polyethylene or the like or directly. Those provided with a layer of an agent or the like have been generally used.

However, in recent years, in addition to demands for cost reduction and high-speed packaging line speed, demand for fashionable packaging materials is also increasing.

Therefore, even in a cap sealing material mainly made of aluminum foil, it is necessary to reduce the thickness of the aluminum foil, which is the most expensive material, but simply thinning it causes a decrease in strength of the cap sealing material as a whole. It lacks practicality. A typical structure of a conventional cap seal is a printing layer / aluminum foil 30 to 40 μm / adhesive layer for heat sealing, but a synthetic resin having high rigidity against strength reduction due to thinning of the aluminum foil. Lamination with a film, for example, a biaxially stretched polyethylene terephthalate film (hereinafter referred to as PET-film) 12 μm / printing / aluminum foil 7 to 9 μm / a cap sealing material having a structure such as an adhesive layer for heat sealing is proposed. It has fulfilled the purpose of the reduction.

[0006] In addition, since the demand for multicolor printing of the cap sealant is increased directly by printing on the aluminum foil, in order to meet the contradictory demands of cost reduction and fashioning, for example, multicolor printing is performed on the outer surface. A cost-saving type cap seal material that combines PET-film and thinned aluminum foil is also used.

[0007] These cap sealing materials are ribbon-shaped cap sealing materials (coil supply type) such as punching molding type or post-sealing punching and bending type when used, and sealing materials cut into a required size of cap seal (sheets). It is supplied in the form of leaf supply type). In recent years, the cap seal material has often been embossed in order to give the cap seal a high-class feel, or in the single-wafer supply type, to prevent two sheets from being taken during the single-wafer supply.

In this case, the PET-film / aluminum foil / heat-seal adhesive layer cap sealing material described above is difficult to emboss due to the elasticity and rigidity of the PET-film. Curling occurs when punching, which makes it extremely difficult to use, and it is difficult to use because it tends to be deformed by punching. Even in the coil supply type, there is a problem that even if it is heat-sealed and punched and then bent, the elasticity of the PET film causes it to spring back and open.

[0009]

[Problems to be solved by the device]

 The present invention uses a reinforcing material that can prevent the strength of the entire cap sealing material from decreasing even when the aluminum foil is made thin, and it is easy to emboss, and it does not curl even when punched into a sheet after embossing The objective is to develop a cost-effective cap seal material that does not deform even if it is bent, and has little springback property even if it is bent after punching.

[0010]

[Means for Solving the Problems]

 The present invention provides a cap sealing material, which is characterized in that a biaxially stretched film of a thermoplastic synthetic resin having a cavity inside having a thickness of 12 to 50 μm, an aluminum foil having a thickness of 7 to 20 μm, and an adhesive layer are laminated. The above objective was achieved by development.

The present invention will be described below with reference to the drawings. The aluminum foil (2) used for the cap sealing material of the present invention is aluminum or aluminum alloy foil used as a conventional cap sealing material and has a thickness of 7 to 20 μm. Avoid making aluminum foil thinner than 7 μm and without pinholes, while avoiding making aluminum foil thicker than 20 μm because it can be sufficiently used without reinforcing material and the material cost becomes expensive. Should be.

As a material for the biaxially stretched film (1) of a thermoplastic synthetic resin having voids inside, a thermoplastic synthetic resin having a relatively high melting point and a high Young's modulus and strength, for example, polyester such as polyethylene terephthalate is used. , Polypropylene, and other engineering plastics can be used, but PET-film is most preferable in terms of price and performance. Then, by utilizing the void generation mechanism at the time of stretching this thermoplastic synthetic resin film, a biaxially stretched film having a cavity inside can be obtained.

The biaxially stretched thermoplastic synthetic resin film having voids inside has 1) cushioning properties as compared with a normal biaxially stretched film. 2) The embossing suitability is dramatically improved. 3) It has a waist because it is stretched despite the presence of cavities. 4) Heat resistance, water resistance, chemical resistance, and weather resistance remain unchanged. 5) It has dimensional stability. 6) Suitable for bending and punching. 7) It is possible to improve the printability and the affinity with the adhesive for the surface characteristics depending on the application. Due to such properties, it is possible to solve the problems of the conventional cap seal material using a biaxially stretched film as a reinforcing material.

If the content of this cavity is expressed as specific gravity in the biaxially stretched PET-film, it is 1. Is a ^{0g / cm 3 ~1.3g / cm 3} .

When the specific gravity is more than 1.3, the embossing property, the bending processability (the springback property is large) and the curling property are not sufficiently improved. On the other hand, when the specific gravity is less than 1.0, the dimensional stability with respect to temperature is deteriorated, making it unsuitable for pitch printing.

A particularly preferred when specific gravity of void content to be 1.05g / cm ³ ~1.2g / cm ³ order, together with the most can be solved problems of PET- has been the problem with the conventional film, It is possible to prevent deterioration of temperature characteristics such as heat shrinkability.

As the adhesive layer [(3) in FIG. 1 or (31) and (32) in FIG. 2], the adhesive layer conventionally used for cap sealing materials can be used as it is.

For example, low density polyethylene 20 to 40 μm / hot melt 10 to 25 g / m ² And a sealant film such as a low density polyethylene or a composition obtained by blending an ethylene-vinyl acetate copolymer therewith.

The biaxially stretched film of thermoplastic synthetic resin containing voids inside and the aluminum foil are laminated using a dry laminating adhesive such as urethane or polyester. Further, the aluminum foil and the adhesive layer may be adhered by dry lamination as in the above, or may be laminated by a method such as extrusion laminating the adhesive layer on the aluminum foil.

[0020]

[Action]

 In order to reduce the cost of the cap seal material, there has been proposed a cap seal material in which the thickness of the aluminum foil is reduced and its strength is reduced by stacking the PET film as a reinforcing material, but the elasticity, rigidity and easiness of deformation of the PET film are proposed. Due to such factors, the difficulty of embossing, curling, and insufficient bending back due to springback were unavoidable.

In the present invention, the void generation mechanism during biaxial stretching is used to generate cavities inside the stretched film, thereby lowering the Young's modulus of the stretched film, which is a problematic embossing process. It is possible to improve curability, prevent curling, and reduce springback property.

Further, since it is sufficiently biaxially stretched, it has sufficient tensile strength in spite of the fact that it has cavities, making it possible to speed up the packaging line, reduce costs, and improve productivity.

[0023]

【Example】

The following samples A to C were prepared. (A) Biaxially stretched PET-film (trade name; Crisper: Polyester synthetic paper manufactured by Toyobo Co., Ltd.) having a specific gravity of 1.1 g / cm ³ printed in 5 colors and having voids inside and having a thickness of 25 μm ( 1), a 7 μm thick aluminum foil (2), and a 50 μm thick ethylene-vinyl acetate copolymer film (3) laminated with a urethane dry laminate adhesive;

(B) Bicolor stretched PET-film (1) having a thickness of 12 μm and having a specific gravity of 1.1 g / cm ³ printed in five colors, aluminum foil (2) having a thickness of 7 μm, and wax A cap seal material in which a low-density polyethylene film (31) having a thickness of 20 μm obtained by coating a blended polyethylene-based hot melt (32) to a thickness of 20 g / m ² is sequentially laminated with a urethane-based dry laminating adhesive;

(C) A commercially available PET-film (1) having a thickness of 12 μm, a 5-color printed aluminum foil (2) having a thickness of 7 μm, and an ethylene-vinyl acetate copolymer film (3) having a thickness of 50 μm were used. Cap seal material laminated in sequence with urethane-based dry laminate adhesive;

The samples obtained above were evaluated for embossing property, curling property after punching, punching formability, and bending workability. The results are shown in Table 1.

[0027]

[Table 1]

[0028]

[Effect of device]

 In order to reduce the cost by thinning the aluminum foil used for the cap sealing material, improve the workability, and speed up the heat sealing line, in place of the PET-film used as a reinforcing material, which is conventionally used, inside By using a biaxially stretched film of thermoplastic synthetic resin containing cavities, embossability, which has been a problem of PET-film, curling property after punching, punching formability (deformation after punching), bending process In addition to solving the problem of spring-back property, the problem of curling of cap seal material, taking two sheets, and spring-back, which had been the cause of problems in the heat-sealing line, was solved, and speed-up is possible. , Productivity has become possible.

[Brief description of drawings]

FIG. 1 is a sectional view of an example of a cap sealing material of the present invention.

FIG. 2 is a sectional view of another example of the cap sealing material of the present invention.

[Explanation of symbols]

1 Biaxially Stretched Film of Thermoplastic Synthetic Resin Having Cavity Inside 2 Aluminum Foil 3 Adhesive Layer 31 Polyethylene Film for Hot Melt Support 32 Hot Melt Layer

Claims (3)

[Scope of utility model registration request] 1. A biaxially stretched film of a thermoplastic synthetic resin containing voids inside and having a thickness of 12 to 50 μm / thickness of 7 to 2
A cap sealing material, which is obtained by laminating an aluminum foil / adhesive layer having a thickness of 0 μm. 2. The adhesive layer has polyethylene of 20 to 40 μm.
The cap sealing material according to claim 1, which is 10 to 25 g / m ^{2 in} hot melt or 30 to 70 μm in sealant film. 3. A cap sealant biaxially oriented film containing voids therein is claim 1, wherein the polyester-based synthetic paper of a specific gravity of ^{1.0g / cm 3 ~1.3g / cm 3} .