JPH0655484B2 - 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 of a beverage container mainly composed of paper.

[Prior Art] As a beverage container for milk drinks, fruit drinks, sake, etc., since it is hygienic, water resistant, moisture proof, and heat-sealed, conventionally, a paper is used as a base material and an inner surface is Container constituent materials processed with polyolefins and the like are 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 a material for forming a container.

[Problems to be Solved by the Invention] However, in the case of forming a constituent material using polyester as described above, there is a problem that when the polyester is processed on the surface of the paper substrate, the polyester is not sufficiently adhered to the paper. is there. As a result, when a container having the appearance shown in FIG. 2 is produced using such a laminated material, the following problems occur particularly in the sleeve forming step shown in FIG. That is, in the sleeve forming step, the portions to be sealed with each other are the paper on the outer surface or the polyolefin layer such as polyethylene provided as necessary and the polyester layer on the inner surface. At this time, the water contained in the paper tries to escape to the polyester layer side, so that the polyester layer is bubbled and pinholes are generated.

Therefore, an object of the present invention is to provide a laminated material for a container comprising a paper and a polyester layer, which has excellent adhesiveness between the paper and the polyester layer, and which does not generate an offensive odor due to oxidation during extrusion coating. To provide.

Further, an object of the present invention is, when used in a beverage container, for a container capable of holding a flavor component intrinsic to the beverage, which does not cause pinholes at the time of its preparation, particularly at the time of frame sealing. It is to provide a laminated material.

[Means for Solving the Problems] The inventors of the present invention have made earnest studies in view of the above problems, and as a result, the above object of the present invention is to provide a copolymer of ethylene and an unsaturated carboxylic acid or an ester thereof on a paper, and It has been found to be achieved by providing a laminated material for a container having a heat-sealable polyester layer through a layer composed of a mixture containing 1% by weight or more of polyester.

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
It is mainly composed of a polyester layer 3 provided on the paper substrate 1 via a layer 2 made of a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and 1% by weight or more of polyester. If necessary, for example, a polyethylene layer 4 is provided on the paper base 1 on the side opposite to the polyester layer 3, and the required printing 5 is performed on the polyethylene layer 4.
Can be applied.

The paper constituting the laminated material of the present invention is not particularly limited as long as it can be used as the structural support of the container,
The basis weight is preferably 100 to 400 g / m ² , particularly preferably 200.
It can be used up to 350 g / m ² . As such a material, there is generally used a paperboard, a milk carton base paper, or the like.

In the laminated material of the present invention, the polyester forming the heat-sealable polyester layer provided on the paper is
It is a copolymer of polybasic acid and polyhydric alcohol. As such polybasic acid, those containing isophthalic acid of 10 to 50% of the total 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 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: p-β-hydroxybenzoic acid, p-oxybenzoic acid, ε-oxycaproic acid and other oxyacids: trimellitic acid, trimesic acid,
Examples thereof include aromatic polybasic acids such as 3,3 ′, 5,5′-tetracarboxydiphenyl; aliphatic polybasic acids such as butanetetracarboxylic acid; 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
-Hydroxyethoxy) benzene, 1,3-bis (β-
Glycols such as (hydroxyethoxy) benzene; polyhydric alcohols such as phloroglysin, 1,2,4,5-tetrahydroxybenzene, glycerin, trimethylolethane, trimethylolpropane and pentaerythritol.

The above polyester is preferably unstretched or weakly stretched about 1.1 times from the viewpoint of preventing shrinkage during heat sealing.

The thickness of the polyester layer is arbitrary, but for example, 1
Used in the range of up to 100 μm.

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 polyolefins include low-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene and the like, and examples of inorganic substances include carbon black, talc, gypsum, silica, alumina, calcium carbonate, titanium dioxide, graphite, powder glass. , Powder metal, and the like.

However, in the present invention, it is preferable that the additives as described above are not included from the viewpoint of preventing adsorption of aroma components such as beverages, which are the contents.

In the present invention, a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and 1% by weight or more of polyester is provided as an adhesive layer between the paper and the heat-sealable polyester layer.

The above copolymer preferably has an unsaturated carboxylic acid content of 3 to 12% by weight in order to improve the adhesiveness to paper.
In the case of an ester, the ester component is preferably 1 to 10% by weight. Examples of such unsaturated carboxylic acid or ester thereof include acrylic acid, methacrylic acid,
Methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate and the like can be mentioned.

The polyester contained in the mixture of 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 polyhydric alcohol may each contain, as a comonomer component, another polybasic acid and another polyhydric alcohol similar to those described above for the heat-sealable polyester layer laminated on the paper through the mixture. it can.

The above polyester component is contained in the mixture of the present invention in an amount of 1% by weight or more from the viewpoint of adhesive strength, but preferably 1 to 10%.
It is contained 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 practically difficult, and a thickness of more than 100 μm is not useful for the present invention.

The laminated material of the present invention has a heat-sealable polyester layer mainly on paper as described above through a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and polyester. In addition, a layer made of polyethylene or the like can be further provided on the paper on the side opposite to the mixture layer and the polyester layer. That is, the laminated material of the present invention can have various layer configurations within the scope of the present invention, and examples thereof include a layer configuration of printing ink / polyethylene / paper / mixture / polyester.

The laminated material of the present invention is produced, for example, by the following method.
That is, the mixture according to the present invention is extrusion-coated on paper, and then polyester is extrusion-coated on the mixture, followed by printing on the paper, or by extrusion-coating polyethylene on the paper and then coating the polyethylene layer with the opposite layer. For example, the mixture may be extrusion coated on the paper on the side, polyester may be extrusion coated on the mixture, and then printing may be performed on polyethylene. 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,
Various containers containing beverages such as juice, liquor, coffee, tea, and water can be mentioned. For example, those having the appearance shown in FIG. 2 and having a polyethylene layer on paper as an outer layer can be mentioned. In order to produce the above-mentioned container using the laminated material of the present invention, a step of forming a sleeve as shown in FIG. 3 is first performed as a first step. In this step, the portions to be overlapped and sealed with each other to form a sleeve, that is, the side edge portion of polyethylene as the outer layer and the side edge portion of polyester as the inner layer are frame-treated to seal the overlapped portion, and A container can be prepared by forming the bottom as the second step, filling the contents as the third step, and finally forming the top as the fourth step.

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

Weighing 300g / m coated with 15-20μ polyethylene
After corona discharge treatment was applied to the surface of the white paperboard ² opposite to the polyethylene, 1.0% by weight of polyester (consisting of 40 mol% terephthalic acid, 10 mol% isophthalic acid and 50 mol% ethylene glycol) and an acid were used. A mixture of 9% by weight of ethylene-unsaturated carboxylic acid EMAA (ethylene-methacrylic acid) was extrusion coated to a thickness of 20 μm. Further, the mixture layer was subjected to corona discharge treatment, and then the above polyester was extrusion-coated on the layer so as to have a thickness of 20 μm to obtain a laminated material 1.

Further, Laminate Materials 2 and 3 were produced in the same manner except that the content of polyester in the mixture was changed as shown in Table 1 in the production of Laminate Material 1. A laminate material 4 prepared in the same manner except that the mixture did not contain polyester and only EMAA was used as a laminate material for comparison.

For each of the obtained laminated materials 1 to 4, the adhesive strength between the paper / mixture layer and the mixture layer / polyester layer was examined. The adhesive strength is Tensilon (manufactured by Toyo Baldwin Co., Ltd.) and the peeling speed is 300 mm / min (T-shaped peeling).
It was measured by.

Moreover, the container shown in FIG. 2 was created using each of the obtained laminated materials 1 to 4. At this time, the occurrence of pinholes was investigated when the outer polyethylene layer and the inner polyester (Kodabond) layer were superposed and heat-sealed in the sleeve forming process.

The results are shown in Table 1.

From Table 1, all of the laminated materials 1 to 3 of the present invention in which the polyester layer is provided via the layer of the mixture according to the present invention have high adhesive strength between the paper / mixture and the mixture / polyester layer, that is, the paper and the polyester layer. However, it was an excellent one in which no pinholes were observed during the production of the sleeve.
On the other hand, the laminate material 4 in which the polyester layer was provided on the paper via the layer containing only EMAA without containing polyester in the mixture had insufficient adhesion between the mixture / polyester layer and was insufficient.

[Effects of the Invention] As described in detail above, according to the present invention, in a container laminated material made of paper and polyester, the adhesive property between the paper and polyester is excellent, and an offensive odor due to oxidation or the like is generated during extrusion coating. It is possible to provide the above-mentioned laminated material that does not generate.

When the laminated material of the present invention is used for a beverage container, pinholes can be prevented from being generated at the time of its preparation, especially at the time of frame sealing, and the flavor component inherent in the beverage, which is the content, can be retained. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the laminated material of the present invention, FIG. 2 is a perspective view showing an example of a container made using the laminated material of the present invention, and FIG. FIG. 7 is a perspective view illustrating a sleeve creating step in creating the container illustrated in FIG. 2. <Main reference numbers> 1 ... paper, 2 ... mixture layer 3 ... polyester layer, 4 ... polyethylene layer 5 ... printing, 6 ... sleeve portion 7 ... bottom portion, 8 ... top portion 9 ... polyester Layer (inside) 10 ... Polyethylene layer (outside)

Claims (1)

[Claims] 1. A laminated material for containers having a heat-sealable polyester layer on a paper with a layer comprising a mixture containing a copolymer of ethylene and an unsaturated carboxylic acid or its ester and 1% by weight or more of polyester. .