JPH0745235B2 - Laminated material for containers - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laminated material for a container, and more particularly to a laminated material suitable as a constituent material for a beverage container based on paper having a metal foil.

[Prior Art] Alcohol, whiskey, and other beverages have high penetrability into the container constituent materials, so that as a constituent material of such a beverage container, conventionally, a metal foil such as aluminum via a ionomer layer or the like on paper is conventionally used. Was used. However, when such a metal foil is used, there is a problem that the metal foil is cracked especially at the bent portion of the container, etc. In order to prevent this, a biaxially stretched polyester film is usually provided on the metal foil. . Furthermore, in the case of such a beverage container, its hygiene, water resistance, moisture resistance and heat sealing are possible, and therefore, conventionally on the above-mentioned biaxially stretched polyester film, that is, the portion constituting the inner surface of the container is made of polyolefins. What was processed by etc. was used.

However, when using the constituent materials as described above, since the polyolefin has the property of adsorbing or permeating the flavor component of the beverage, there is a problem that the original scent of the beverage, the taste and the like are not maintained, and further the above materials are used. When it is prepared by extrusion coating of polyolefin, it is prone to oxidation, which causes a problem that an offensive odor is generated.

In order to solve the above problems, in recent years, a material using polyester instead of polyolefin has been used as the constituent material for the container.

[Problems to be Solved by the Invention] However, in the constituent material using polyester instead of polyolefin as described above, a layer made of the polyester has a drawback of lacking flexibility, and therefore, for example, ruled lines are used. At the time of application, there were problems that the polyester layer was cracked at the time of bending in the box making process, and the beverage as the content permeated with the passage of time to cause liquid leakage and peeling.

Therefore, an object of the present invention is to provide a laminated material for a container having a polyester layer on a biaxially stretched polyester film, particularly a metal foil such as aluminum, a biaxially stretched polyester film and a polyester layer in this order on a paper substrate. In a laminated material for a container, there is provided no cracking of the polyester layer at the time of scoring, bending in a box-making process, etc., and liquid leakage or peeling with time does not occur. .

[Means for Solving the Problems] The inventors of the present invention have made earnest studies in view of the above-mentioned problems, and as a result, the above object of the present invention is to provide ethylene and an unsaturated carboxylic acid or an ester thereof on a biaxially stretched polyester film. A layered material for a container having a heat-sealable polyester layer through a layer comprising a mixture containing a copolymer of 1% by weight or more of the polyester with respect to the total weight of the mixture, particularly a metal foil on a paper substrate, and From a mixture having a biaxially stretched polyester film in this order and containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester on the polyester film and 1% by weight or more of the polyester based on the total weight of the mixture. It has been found that this can be achieved by providing a laminated material for a container having a heat-sealable polyester layer through the layer consisting of

Hereinafter, the present invention will be described in more detail.

FIG. 1 is a schematic sectional view showing one example of the laminated material of the present invention. According to FIG. 1, the laminated material of the present invention comprises a paper substrate 1 and
For example, a metal foil 3 provided via the ionomer layer 2
And a biaxially stretched polyester film 4 provided on the metal foil 3 and a layer 5 composed of a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and 1% by weight or more of polyester. It is mainly composed of a polyester layer 6 provided on the biaxially stretched polyester film 4. If necessary, for example, a polyethylene layer 7 is provided on the paper substrate 1 on the side opposite to the polyester layer 6, and desired printing can be performed on the polyethylene layer 7.

The biaxially stretched polyester film constituting the laminated material of the present invention prevents the permeation of the contents due to the crack of the metal foil when the metal foil is contained as a constituent material, and when the metal foil is not contained as the constituent material, For example, when a thermoplastic resin layer is included instead of the metal foil, the content of the thermoplastic resin layer is prevented from permeating through the pinholes of the thermoplastic resin layer.
The polyester resin forming the polyester film comprises a copolymer of polybasic acid and polyhydric alcohol. As such a polybasic acid, one containing terephthalic acid as a main component is preferable, and as a polyhydric alcohol, one containing ethylene glycol as a main component is preferable.
The polybasic acid and the polyhydric alcohol may each include another polybasic acid and another polyhydric alcohol as a comonomer component.

Other polybasic acids that can be contained as a comonomer component in the polybasic acid include aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid and diphenyl sulfone dicarboxylic acid; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid; adipic acid, sebacic acid,
Aliphatic dicarboxylic acids such as azelaic acid; oxy acids such as p-β-hydroxybenzoic acid, p-oxybenzoic acid and ε-oxycaproic acid; trimellitic acid, trimesic acid, 3,
Aromatic polybasic acids such as 3 ', 5,5'-tetracarboxydiphenyl; Aliphatic polybasic acids such as butanetetracarboxylic acid;
Examples thereof include oxypolycarboxylic acids such as tartaric acid and malic acid.

Other polyhydric alcohols that can be contained as a comonomer component in the polyhydric alcohol include trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexanediene. Methylol, 1,4-cyclohexane dimethylol, 2,2-bis (4-β-hydroxyethoxyphenyl) propane, bis- (4-β-hydroxyethoxyphenyl) sulfone cyclohexane, 1,4-bis (β-hydroxy) Glycols such as ethoxy) benzene and 1,3-bis (β-hydroxyethoxy) benzene; phloroglysin, 1,2,4,5-tetrahydroxybenzene, glycerin, trimethylolethane, trimethylolpropane,
Examples include polyhydric alcohols such as pentaerythritol.

In the present invention, the above polyester resin may contain a nucleating agent or various additives such as a lubricant, an antiblocking agent, a stabilizer, an antifogging agent, and a colorant. As such a nucleating agent, fine particles of polyolefin or inorganic material having a particle size of 2 to 10 μm are used. Examples of the polyolefins include low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene and the like, and examples of the inorganic material include carbon black, talc, gypsum, silica, alumina, calcium carbonate, titanium dioxide, graphite, powder glass. , Powder metal, and the like.

The biaxially stretched polyester in the present invention is preferably the above polyester resin which is biaxially stretched 4 to 6 times in the longitudinal direction and 4 to 6 times in the transverse direction after molding, and the biaxially stretched heat set is preferably used. To be The biaxially stretched polyester film obtained as described above preferably has a thickness of 9
~ 25μ.

In the laminated material of the present invention, the polyester forming the heat-sealable polyester layer provided on the biaxially stretched polyester film is a copolymer of polybasic acid and polyhydric alcohol. As such polybasic acid, those containing isophthalic acid of 10 to 50% of all acid components and terephthalic acid as main components are preferable, and those of polyhydric alcohols containing ethylene glycol as main components are preferable. The polybasic acid and the polyhydric alcohol may each contain, as a comonomer component, another polybasic acid and another polyhydric alcohol similar to the polyester resin forming the biaxially stretched polyester film.

Further, the polyester resin may contain various additives such as a nucleating agent, a lubricant, an anti-blocking agent, a stabilizer, an antifogging agent, and a coloring agent, like the polyester of the biaxially stretched polyester film, but is preferable. Is preferably not included from the viewpoint of preventing adsorption of aroma components such as beverages which are contents.

As the polyester used for the heat-sealable polyester layer, from the viewpoint of preventing shrinkage during heat-sealing, non-stretched polyester or weakly stretched 1.1 times is preferably used.

The heat-sealable polyester layer may have any thickness, but is used in the range of, for example, 1 to 100 μm.

In the present invention, between the biaxially stretched polyester film and the heat-sealable polyester layer, 1% by weight or more of polyester based on the total weight of the copolymer of ethylene and unsaturated carboxylic acid or its ester and the mixture is used. The mixture containing is provided as an adhesive layer.

The above copolymer has an unsaturated carboxylic acid content of 3 to
It is preferably 12% by weight, and in the case of ester, the ester component is preferably 1 to 10% by weight. Examples of such unsaturated carboxylic acids or esters thereof include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate and the like.

The polyester contained in the mixture according to the present invention is a copolymer of a polybasic acid and a polyhydric alcohol and is contained in order to improve the adhesiveness with the polyester layer. It is preferable that such a polybasic acid contains terephthalic acid as a main component, and that the polyhydric alcohol contains ethylene glycol as a main component.

The polybasic acid and the polyhydric alcohol may each contain, as a comonomer component, another polybasic acid and another polyhydric alcohol similar to those described above regarding the polyester constituting the biaxially stretched polyester film.

The above-mentioned polyester component is contained in the mixture according to the present invention in an amount of 1% by weight or more from the viewpoint of adhesive strength, but preferably 1 to
Contains 10% by weight.

The layer composed of the above mixture usually has a thickness of 1 to 100 μm. That is, a thickness of less than 1 μm is difficult in practice, and a thickness of more than 100 μm is not useful for the present invention.

The laminated material of the present invention mainly has a polyester layer on a biaxially stretched polyester film as described above through a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and polyester, When this laminated material is used for a beverage container or the like, a metal foil and the biaxially stretched polyester film are provided in this order on paper, and the heat-sealing polyester is further provided on the polyester film via the mixture layer according to the present invention. It is advantageous to have a construction with layers.

The paper used for the above-mentioned laminated material is not particularly limited as long as it can be used as a structural support of the container,
Preferably weighed value of 100 to 400 g / m ² , particularly preferably 200 to 3
50g / m ² can be used. As such a material, there is generally used a paperboard, a milk carton base paper or the like.

The thickness of the metal foil provided on the paper is 6 to 20.
Those made of aluminum having a thickness of μm are preferably used. Such a metal foil is provided on the paper by using, for example, polyethylene, ethylene-methacrylic acid copolymer, ionomer resin or the like. A layer made of polyethylene or the like may be provided on the paper opposite to the metal foil.

The laminated material of the present invention can have various layer constitutions within the scope of the present invention, and for example, printing ink / polyethylene /
Examples of the layer structure include paper / ionomer / aluminum foil / biaxially stretched polyester film / mixture / polyester.

The laminated material of the present invention is produced, for example, by the following method.
That is, (1) polyethylene is extrusion coated on paper and printing is performed on the polyethylene. On the other hand, (2) a biaxially stretched polyester film is dry-laminated on an aluminum foil, and then the mixture according to the present invention is extrusion-coated on the polyester film, and then a polyester layer is extrusion-coated on the layer formed of the mixture.
(3) The paper surface of (1) and the aluminum foil surface of (2) are adhered via polyethylene, an ionomer resin, an ethylene-methacrylic acid copolymer or the like. Further, as another method, the step (2) above is carried out by co-extruding the mixture according to the present invention and polyester, and then extruding the mixture on the surface of the biaxially stretched polyester film of the aluminum foil and the biaxially stretched polyester film which are dry laminated. Laminate it,
The steps (1) and (3) can be prepared in the same manner as above.

In the extrusion coating, each layer of paper, polyethylene, and a mixture may be subjected to surface treatment such as corona discharge treatment, if necessary.

As a container to which the laminated material of the present invention can be preferably applied,
There are various types of containers having contents such as highly permeable liquid beverages such as sake, whiskey, juice, coffee, barley tea, oolong tea, soups, and the like.
Tetra Pak type and block type containers whose appearances are shown in FIGS. 3 and 4 are exemplified. In order to prepare the container shown in FIG. 2 using the laminated material of the present invention, first,
As a step, a step of forming a sleeve as shown in FIG. 4 is performed. In this step, one side edge portion is folded back to form a sleeve so that the end surface of the container constituent material is exposed to the inner surface of the container and does not touch the beverage as the content, that is, a surface overlaid on each other, that is, an inner layer. Frame the side edges of the polyester that is
Then, a bottom can be formed as a second step, the contents can be filled as a third step, and finally a top can be formed as a fourth step to form a container.

As another method, it is possible to form a container by heat-sealing polyester surfaces when the roll-shaped laminate material of the present invention is filled in the contents.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples.

Polyester containing terephthalic acid as the main component as polybasic acid and ethylene glycol as the main component as polyhydric alcohol was stretched 6 times in each length and width and heat-set to a thickness of 12
A biaxially stretched polyester film of μ and a 9 μm thick aluminum foil were dry-laminated using a two-component curing type urethane adhesive, and 1.0% by weight of polyester (40 mol of terephthalic acid was added to the polyester film side of the obtained laminated film. %, Isophthalic acid 10 mol%, ethylene glycol 50 mol%) and acid component of 9 wt% ethylene-
A mixture of unsaturated carboxylic acid EMAA (ethylene-methacrylic acid) was press coated to a thickness of 40μ. Further, a layer made of the mixture was subjected to corona discharge treatment, and then the above polyester was extrusion coated to a thickness of 20 μm. Then, the aluminum foil surface of the laminate film is adhered by an ionomer resin to the surface of the white paperboard coated with 15 to 20 μm of polyethylene and weighing 300 g / m ² on the side opposite to the polyethylene layer, and the laminated material 1 of the present invention
It was created.

In addition, Laminate Materials 2 to 4 were produced in the same manner except that the content of polyester in the mixture or the weight of paper in the mixture was changed as shown in Table 1 in the production of Laminate Material 1. Furthermore, in the production of the laminated material 1, without providing a mixture layer,
A laminate material 5 was prepared in the same manner except that the thickness of the polyester layer was set to 60 μ and was directly provided on the biaxially stretched polyester film. In the preparation of the laminate material 5, the paper weight was changed as shown in Table 1 in the same manner. And a laminated material 6 was prepared.

For each of the obtained laminated materials 1 to 6, a container having the shape shown in FIG. 2 was created. At this time, the leakage of liquid in the bent portion or the occurrence of cracks in the polyester layer during ruled line formation was examined. The results are shown in Table 1.

From Table 1, all of the containers obtained from the laminated materials 1 to 4 of the present invention in which the polyester layer is provided via the layer of the mixture according to the present invention, are leaked from the folded portion, and cracks are generated in the polyester layer. Nonetheless, it was an excellent beverage container.

[Effects of the Invention] As described in detail above, by using the laminated material of the present invention, cracking of the polyester layer does not occur at the time of scoring, bending during the box making process, etc., and liquid leakage over time It is possible to provide a beverage container without peeling.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the laminated material of the present invention, and FIGS. 2 and 3 are perspective views showing an example of a container made using the laminated material of the present invention. FIG. 4 is a perspective view showing a sleeve producing step in producing the container shown in FIGS. 2 and 3. <Main reference numbers> 1 ... paper, 2 ... adhesive layer 3 ... metal foil 4 ... biaxially oriented polyester film 5 ... mixture layer 6 ... heat sealable polyester layer 7 ... polyethylene layer, 8 ... … Sleeve part 9 …… Bottom part, 10 …… Top part 11 …… Polyester layer (inside) 12 …… Polyethylene layer (outside)

Claims (2)

[Claims] 1. A biaxially stretched polyester film,
A laminated material for a container having a heat-sealable polyester layer via a layer formed of a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and 1% by weight or more of polyester based on the total weight of the mixture. 2. A metal foil and a biaxially stretched polyester film are provided in this order on a paper substrate, and the weight of the whole copolymer and mixture of ethylene and an unsaturated carboxylic acid or its ester is mixed on the polyester film. To 1% by weight
Through a layer composed of a mixture containing the above polyester,
A laminated material for a container having a heat-sealable polyester layer.