JP2010125796A - Biodegradable laminate packaging material and food packaging container using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable laminate packaging material having heat resistance and oil resistance. <P>SOLUTION: The laminate packaging material includes a paper layer and a biodegradable resin layer which is laminated on the paper layer. The biodegradable resin layer contains as a principal component a biodegradable resin being a polyethylene terephthalate copolymer which has recurring units consisting of terephthalic acid, metal sulfonate, aliphatic dicarboxylic acid, ethylene glycol, diethylene glycol and polyethylene glycol, wherein, in the acid components, terephthalic acid is 50 mol% to 90 mol%, metal sulfonate is 0.2 mol% to 6 mol% and aliphatic dicarboxylic acid is 4 mol% to 49 mol% and, in glycol components, ethylene glycol is 50 mol% to 99.9 mol%, diethylene glycol is 0.1 mol% to 50 mol% and polyethylene glycol is 20 mol% or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a biodegradable laminated packaging material and a food packaging container using the same.

At present, a laminate packaging material in which a paper layer and a synthetic resin layer typified by polyethylene, polypropylene and the like are laminated is in circulation. Such laminated packaging materials are used as packaging containers having various forms as required.
Since this type of laminated packaging material is a composite of paper and synthetic resin, it is difficult to separate and is incinerated or landfilled after use.
However, when incinerated, carbon dioxide is generated, which contributes to global warming. In addition, when the landfill process is performed, the synthetic resin is difficult to be decomposed, which has an adverse effect on the natural environment.

  For these reasons, development of a biodegradable laminated material that can be decomposed into carbon dioxide gas and water in a natural environment even after landfill treatment is awaited. In addition, even if incinerated, development of a packaging material that can reduce the generation of carbon dioxide compared to synthetic resins such as polyethylene is awaited.

  Here, as the biodegradable resin, starch, polylactic acid, polyvinyl alcohol, chitosan, cellulose acetate, poly-3-hydroxybutyric acid, polybutylene succinate, polybutylene succinate adipate, polyethylene succinate, polyethylene succinate Examples include adipate, polybutylene adipate / terephthalate, polycaprolactone, and the like.

The lamination of the paper layer and the resin layer is preferably performed by supplying the resin directly to the paper layer and bonding it by a melt extrusion method.
At that time, in order to improve the adhesive force of the biodegradable resin as described above to the paper layer, it is necessary to raise the molten resin temperature to some extent.
However, when the molten resin temperature is increased, the viscosity of the molten resin decreases, the flowability of the molten film extruded from the die die becomes uneven, the separation of the cooling roll becomes worse, and the peeling force works on the adhesive surface, There was a problem that adhesion of the molten resin to the surface of the paper layer became unstable, resulting in difficulty in lamination.

In order to deal with such a problem, for example, the following various methods have been tried.
One of these methods is a dry laminating method in which a biodegradable film such as polylactic acid formed in advance is laminated with paper using an adhesive.
However, this method has the disadvantages of many steps and high cost.

As another method, Patent Document 1 discloses a method in which a biodegradable resinous polymer blend containing a biodegradable resin having good adhesion to paper is directly laminated on a paper layer by a two-layer co-extrusion method. Is disclosed.
Patent Document 2 discloses a method of laminating a specific polybutylene succinate on the surface of a paper layer.

However, in the method of Patent Document 1, two extruders are necessary, and the die for the die is also special for two layers.
Further, the method of Patent Document 2 has a problem that the biodegradable resin does not have heat resistance and cannot be used as it is in a microwave oven or an oven. Similarly, since the biodegradable resin does not have oil resistance, when an oily food is contained in a packaging container prepared using the laminate, the oil oozes out to the outer surface of the packaging container. There is a problem.
JP 2004-98321 A JP 2006-247876 A

  An object of the present invention is to provide a biodegradable laminated packaging material and a packaging container with higher practicality.

  As a result of searching various suitable resins as a more practical biodegradable laminated packaging material, the present inventor is suitable for laminating paper layers by a melt extrusion method, The inventors found for the first time that they had good heat resistance and oil resistance and completed the present invention.

  The laminated packaging material of the present invention is a laminated packaging material having a paper layer and a biodegradable resin layer laminated on the paper layer, the biodegradable resin layer comprising terephthalic acid, a sulfonic acid metal salt, It has a repeating unit consisting of aliphatic dicarboxylic acid, ethylene glycol, diethylene glycol, and polyethylene glycol, and in the acid component, terephthalic acid is 50 mol% to 90 mol%, and sulfonic acid metal salt is 0.2 mol% to 6 mol. Mol%, aliphatic dicarboxylic acid is 4 mol% to 49 mol%, ethylene glycol is 50 mol% to 99.9 mol%, diethylene glycol is 0.1 mol% to 50 mol%, polyethylene glycol in the glycol component The biodegradable resin is mainly composed of a biodegradable resin which is a polyethylene terephthalate copolymer having a content of 20 mol% or less. A laminated packaging material.

Since the material for forming the biodegradable resin layer is as described above, the biodegradable resin layer can be directly adhered to the paper layer and laminated by melt extrusion. In addition, heat resistance for cooking by indirect heating can be provided, and sufficient oil resistance can be ensured.
Thus, according to the present invention, a practical biodegradable laminated packaging material that has not been conventionally provided is provided for the first time.
That is, with respect to the polyethylene terephthalate copolymer used for the biodegradable resin layer of the laminated packaging material of the invention, it is suitable for laminating by direct melt extrusion to the paper layer, cooking by indirect heating, etc., and The oil resistance was not studied at all, and application to the laminated packaging material was not assumed at all.
Under such circumstances, the present inventor has developed a laminated packaging material using the above-described polyethylene terephthalate copolymer.

In the laminated packaging material of the present invention, the polyethylene terephthalate copolymer preferably has a crystal melting point of 190 ° C. or higher and 210 ° C. or lower.
Moreover, you may use for cooking containers by indirect heating. In particular, it can be used for cooking containers using a microwave oven, an oven toaster, an oven, and the like. It can also be used for oil-based foods.

Moreover, the food packaging container of this invention is a food packaging container which equips at least one part with the said laminated packaging material.
The food packaging container of the present invention may be a container for cooking by indirect heating as it is. In particular, it can be used for cooking containers using a microwave oven, an oven toaster, an oven, or the like. It may be used for oil-based foods. Moreover, a bag-like body may be sufficient and the transparent site | part which consists of a biodegradable resin layer transparent to the extent which can visually recognize an inside may be provided in a part of the said laminated packaging materials.

  As described above, according to the present invention, a highly practical biodegradable laminated packaging material and food packaging container can be obtained.

  Hereinafter, various embodiments of the present invention will be described in detail.

[Laminated packaging materials]
The laminated packaging material of the present invention includes a paper layer and a biodegradable resin layer having a specific composition laminated on the paper layer. In the laminated packaging material of the present invention, generally, the paper layer is disposed on the outer layer side, and the biodegradable resin layer is disposed on the inner layer side.

The thickness of the paper layer and the mass per unit area (weighing) are not particularly limited.
Also, the paper quality is not particularly limited, and various known papers used for this type of laminated packaging material can be used. Examples thereof include high-quality paper, bleached kraft paper, kraft paper, thin paper, pure white roll paper, imitation paper, paperboard, and cardboard.

The biodegradable resin layer is mainly composed of a biodegradable resin that is a polyethylene terephthalate copolymer having a specific composition.
The thickness and weight of the biodegradable resin layer are not particularly limited.
The polyethylene terephthalate copolymer is composed of an acid component and a glycol component each having a specific range of composition. In addition, although the usage-amount of a glycol component is substantially equimolar with respect to 100 mol of acid components, generally 1 mol% or more and about 20 mol% or less are used excessively.

The polyethylene terephthalate copolymer has repeating units composed of terephthalic acid, sulfonic acid metal salt, aliphatic dicarboxylic acid, ethylene glycol, diethylene glycol, and polyethylene glycol.
In the acid component of the copolymer component, terephthalic acid is 50 mol% or more and 90 mol% or less, sulfonic acid metal salt is 0.2 mol% or more and 6 mol% or less, and aliphatic dicarboxylic acid is 4 mol%. It is preferable that it is 49 mol% or less.
Preferably, terephthalic acid is 60 mol% or more and 85 mol% or less, sulfonic acid metal salt is 1 mol% or more and 4 mol% or less, and aliphatic dicarboxylic acid is 4 mol% or more and 20 mol% or less.

Further, in this copolymer component, the glycol component is preferably 50 mol% to 99.9 mol% of ethylene glycol, 0.1 mol% to 50 mol% of diethylene glycol, and 20 mol% or less of polyethylene glycol. .
More preferably, ethylene glycol is 75 mol% to 99 mol%, diethylene glycol is 1 mol% to 25 mol%, and polyethylene glycol is 2 mol% to 18 mol%.

The crystal melting point of the polyethylene terephthalate copolymer used in the present invention is preferably 190 ° C. or higher and 210 ° C. or lower.
The crystal melting point can be determined from the peak in DSC.

In addition to the above-described polyethylene terephthalate copolymer, the biodegradable resin layer of the present invention may contain other biodegradable resins as long as the effects of the present invention are not impaired.
Specific examples include polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polybutylene adipate / terephthalate.
Further, known additives such as antioxidants, antistatic agents, lubricants, hydrolysis inhibitors, colorants, anti-blocking agents and the like can be appropriately added to the biodegradable resin layer of the present invention.

The laminated packaging material of the present invention is suitable as a packaging material for cooking containers by indirect heating. That is, it has good heat resistance against such cooking, typically heating of cooking utensils by indirect heating such as a microwave oven, oven, oven toaster and the like.
Such heat resistance is due to the polyethylene terephthalate copolymer having the specific composition described above.
The laminated packaging material of the present invention is suitable for a packaging material for oily food. This is because even if oily food is packaged, it is possible to effectively prevent oil from seeping out to the surface.
Such oil resistance is also due to the polyethylene terephthalate copolymer having the specific composition described above.

[Manufacture of laminated packaging materials]
The laminated packaging material of the present invention described above can be easily produced by a known extrusion laminate forming method, that is, a melt extrusion method.
The lamination thickness of the biodegradable resin is 10 μm to 50 μm, and is appropriately changed depending on the application.
Moreover, although extrusion temperature changes with lamination | stacking thickness and paper quality, it is the range of 200 to 280 degreeC, Preferably it is 210 to 270 degreeC. Below 210 ° C, the adhesiveness to the paper layer surface is weak, and above 270 ° C, the neck-in of the molten resin becomes large, thermally decomposes, the peelability from the cooling roll deteriorates, and once adheres to the paper surface. This is because a problem that the resin film is peeled off occurs.

  The laminated packaging material of the present invention can laminate a biodegradable resin layer with good integrity on a paper layer by a melt extrusion method. This is due to the polyethylene terephthalate copolymer that is the main component of the biodegradable resin layer.

[Food packaging containers]
The food packaging container of the present invention can be provided with at least a part of the laminated packaging material of the present invention.
According to the food packaging container of the present invention, since the laminated packaging material of the present invention is provided, the food packaging container has good integrity with the paper layer and is excellent in heat resistance and oil resistance.
For this reason, like the laminated packaging material of the present invention, the food packaging container of the present invention is useful as a container for cooking by indirect heating, and also useful for oily foods.

  The form of the food packaging container is not particularly limited, and various forms of known food packaging containers can be arbitrarily adopted. Examples of such forms include a bag-like body, a tray, and a combination of a tray and a lid. The form of the food packaging container of the present invention is preferably a bag-like body.

The food packaging container of the present invention can be provided with a transparent portion made of a biodegradable resin layer that is transparent to the extent that the inside can be visually recognized in a part of the laminated packaging material. More specifically, the outer layer can be provided with a transparent portion having only a biodegradable resin layer without a paper layer.
By providing such a transparent part, the contents, that is, the food that is the package body can be visually recognized from the outside.
Since the biodegradable resin of the present invention is excellent in transparency and moldability during melt extrusion, such a transparent portion can be easily formed.

The food packaging container of the present invention can be manufactured by a known method as this type of manufacturing method. For example, an example of manufacture of the food packaging container which is a bag-like body is shown below.
First, a rectangular laminated packaging material is prepared, and after the valley is folded with the biodegradable resin layer inside, the side part continuous from the valley folded part (that is, the side part when the bag is formed) By heat-sealing the corresponding part), a bag-like body having an opening on the side opposite to the valley-folded part can be produced. If necessary, the bottom part can also be heat-sealed to make a bag.

Moreover, in order to form a transparent site | part, various well-known methods are employable as a manufacturing method of this kind of transparent site | part. For example, a paper layer provided with an opening corresponding to a transparent part is prepared in advance, and a laminated packaging material having a transparent part is obtained by laminating a biodegradable resin on the paper layer.
A food packaging container can be produced by a known method using such a laminated packaging material.
A laminated packaging material having a transparent part is prepared by laminating a biodegradable resin on a paper layer having no opening by melt extrusion, and then removing a part of the paper layer to form an opening. Also good.

  Hereinafter, specific examples of the present invention will be described. Note that the present invention is not limited to these examples.

<Example 1>
As a biodegradable resin, “Biomax 4024” (crystal melting point: 199 ° C.) manufactured by DuPont Co., Ltd. was used to melt and extrude the surface of bleached kraft paper having a weight of 50 g / m ² at a temperature of 250 ° C. by melt extrusion. The degradable resin was laminated so as to have a thickness of 15 μm. Thus, a laminated packaging material having biodegradability and good integrity between the paper layer and the biodegradable resin layer was produced.
Using this laminated packaging material, the biodegradable resin surface was folded inside, and then both sides were heat sealed to produce a food packaging bag.
The side dish fried in oil was put into the food packaging bag and heated in a microwave oven with a rated high-frequency output of 500 W for 2 minutes or in an oven for 5 minutes.
As a result, in any case, the inner surface of the bag was not fused, and no oil oozes out to the outer surface of the bag.

<Example 2>
Using “Biomax 4026” (crystal melting point: 195 ° C.) manufactured by DuPont as a biodegradable resin, the biodegradable resin has biodegradability as in Example 1, and the paper layer and the biodegradable resin layer are integrated. A good laminated packaging material was produced.
Using this laminated packaging material, the biodegradable resin surface was folded inside, and then both sides were heat sealed to produce a food packaging bag.
The side dish fried in oil was put into the food packaging bag and heated in a microwave oven with a rated high-frequency output of 500 W for 2 minutes or in an oven for 5 minutes.
As a result, in any case, the inner surface of the bag was not fused, and no oil oozes out to the outer surface of the bag.

<Comparative Example 1>
Using polybutylene succinate having a melting point of 110 ° C. as the biodegradable resin, the biodegradable resin has a thickness of 15 μm with respect to the surface of bleached kraft paper weighing 50 g / m ² at a temperature of 240 ° C. Laminated. In this manner, a laminated packaging material having biodegradability was produced in the same manner as in Example 1.
Using this laminated packaging material, a food packaging bag was produced in the same manner as in Example 1.
And like Example 1, the side dish fried in oil was put into the food packaging bag, and it heated for 2 minutes with the microwave oven, or heated for 5 minutes with the oven.
As a result, in any case, the inner surface of the bag was fused by heat, and the oil oozed out to the outer surface of the bag, which was impractical.

Claims (9)

A laminated packaging material having a paper layer and a biodegradable resin layer laminated on the paper layer,
The biodegradable resin layer is
Having a repeating unit consisting of terephthalic acid, sulfonic acid metal salt, aliphatic dicarboxylic acid, ethylene glycol, diethylene glycol, and polyethylene glycol,
In the acid component, terephthalic acid is 50 mol% to 90 mol%, sulfonic acid metal salt is 0.2 mol% to 6 mol%, aliphatic dicarboxylic acid is 4 mol% to 49 mol%,
In the glycol component, ethylene glycol is 50 mol% to 99.9 mol%, diethylene glycol is 0.1 mol% to 50 mol%, and polyethylene glycol is 20 mol% or less. Biodegradable resin that is a polyethylene terephthalate copolymer Is the main component,
Laminated packaging material with biodegradability.   The laminated packaging material according to claim 1, wherein the polyethylene terephthalate copolymer has a crystal melting point of 190 ° C or higher and 210 ° C or lower.   The laminated packaging material according to claim 1 or 2, which is used for cooking by indirect heating.   The laminated packaging material according to any one of claims 1 to 3, which is used for oil-based foods.   A food packaging container comprising at least a part of the laminated packaging material according to any one of claims 1 to 4.   The food packaging container according to claim 5, which is a container for cooking by indirect heating.   The food packaging container according to claim 5 or 6, which is used for oil-based foods.   The food packaging container according to any one of claims 4 to 6, which is a bag-like body.   The food packaging container according to any one of claims 4 to 6, further comprising a transparent portion made of the biodegradable resin layer that is transparent to such an extent that the inside can be visually recognized.