JP2895767B2 - Liquid paper container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of heating contents by a microwave oven, has a high gas barrier property,
The present invention relates to a liquid paper container that can be easily incinerated (no pollution).

[0002]

2. Description of the Related Art In recent years, with the increase in women's entry into society, the increase in the purchase of foods in superstores, convenience stores, and the like, and changes in packaging formats, the sales of food and beverages in containers made of liquid paper have rapidly increased. It has increased. So-called ordinary liquid paper containers are manufactured from blank sheets in which aluminum foil with a thickness of 7 μm or more is laminated together with paper and plastic film. When discarded and incinerated, aluminum reacts to the refractory material of the incinerator. However, it is known that the life of the incinerator is shortened, and since it is protected by plastic even in landfills, it has no decomposability. is there.

The structure of a general aluminum foil-containing paper container is as shown in FIG. 2, in which a polyethylene layer C, a polyethylene terephthalate (hereinafter referred to as PET) layer B, an aluminum foil layer A, Paper layer D,
The polyethylene layer C is laminated in this order, and the aluminum gas layer A is laminated in the blank sheet of the container to maintain the oxygen gas barrier property and the light shielding property.
In order to maintain the same oxygen gas barrier property except for the aluminum foil from such a configuration, it has been proposed to use a gas barrier resin such as saponified ethylene-vinyl acetate copolymer (EVOH). The oxygen gas barrier property of the water-soluble resin is greatly affected by the environmental humidity,
In the case of high humidity, the barrier property is greatly reduced, so when the content is an aqueous liquid, it is insufficient as a container for storing at room temperature, and is limited to cases such as frozen storage or refrigerated storage. .

Further, a proposal has been made for a liquid paper container manufactured from a blank sheet using a plastic layer having a silicon oxide thin film layer on at least one surface in place of aluminum foil in the blank sheet (Japanese Utility Model Publication No. 5-28190). ). It states that this paper container has a high barrier property that can directly heat the contents and protect the contents in a microwave oven.
The thin film layer of silicon oxide formed by vapor deposition or the like in T)
It is weak against elongation and bending, easily damaged by bending and impact at the time of packaging, shock in handling of packaged goods, etc., cannot maintain a stable barrier property, and the barrier property of oxygen gas is It is unsatisfactory and is not preferable as a container for contents that need to be stored at room temperature.

[0005] For example, by applying a thermal shock when an adhesive layer such as polyethylene is provided for bonding to a paper layer, or by applying external stress or ruled lines when manufacturing a liquid paper container from the laminated blank sheet. Cracks and pinholes are easily generated in the brittle thin film, and the barrier property as proposed above cannot be maintained, and as a packaging material requiring a high and stable barrier property like a room temperature storage paper container using aluminum foil. Is not practical.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a liquid paper container not using aluminum foil, which has a high oxygen gas barrier property similarly to a liquid paper container using aluminum foil for storage at room temperature. Another object of the present invention is to provide a container made of liquid paper that can be incinerated in an incinerator without losing barrier properties due to handling.

[0007]

According to the present invention, a plastic layer (I) / a plastic layer (II) / a thin film layer of a silicon oxide coated with a hydroxyl group-containing thermoplastic resin in order from an inner layer to an outer layer / paper. The above object has been attained by developing a container made of liquid paper, characterized in that the container is formed from a blank sheet having a laminated structure mainly composed of a layer / adhesive layer / cardboard layer laminate.

In the present invention, the plastic layer (I)
Is a thermoplastic resin layer that can be heat-sealed such as extrusion-coated low-density polyethylene resin, high-density polyethylene resin, polypropylene resin, ethylene-vinyl acetate copolymer, and has a thickness of about 10 to 60 μm. You. Plastic layer (II) is PET, ON, OP
It is a layer made of a film having a strength such as P, and silicon oxide is vapor-deposited on this plastic film before use. Silicon oxide is usually represented by the general formula SiO _x (where x =
Many are in the 1.4-1.9 rank. )
The thickness of the vapor-deposited film is about 200 to 2000 mm, and is usually vapor-deposited on the plastic (II) layer.

Hydroxy group-containing thermoplastic resins include EVOH and polyvinyl alcohol (PV) having oxygen barrier properties.
A) or the like, a resin composition containing at least one thermoplastic resin having a large number of hydroxyl groups in the molecule or an unsaponifiable ethylene-vinyl acetate copolymer (unsaponifiable EVA) is used. It is desirable that the amount of unsaponified EVA is at most 99% by weight, preferably 10 to 90% by weight in the resin composition. By blending unsaponified EVA, the flexibility of the hydroxyl-containing thermoplastic resin layer can be further improved. It is said that EVOH and the like have an oxygen barrier property by themselves, but such a resin layer alone cannot provide a high oxygen gas barrier property, so that it is necessary to use them in combination.

However, the hydroxyl group in the resin layer and the SiO _x of the silicon oxide vapor-deposited film have a synergistic effect in the barrier property due to the hydrational bond, and the flexibility of the resin is silicon oxide. The object of the present invention is to eliminate the brittleness of the deposited film and improve the moldability and impact resistance of the multilayer body including the deposited SiO _x film. For this reason, by applying this resin, it is possible to prevent the silicon oxide vapor deposition film from being damaged by thermal stress, mechanical shock, etc. during the manufacture of a box or during the transportation of a packaged product, etc. This is to maintain a stable barrier property against In order to exhibit this function, the resin layer needs to have a thickness of at least 1 μm, and a thickness of 20 μm or less is preferable in consideration of cost.

[0011] The paper quality of the paper layer adjacent to the hydroxyl-containing thermoplastic resin layer is not particularly limited, and an ordinary basis weight of about 3
Fine paper of about 0 to 80 g / m ² may be used. This is SiO _x
This is necessary for winding after bonding to the hydroxyl group-containing thermoplastic resin applied to the vapor deposition layer, and laminating the layers facilitates the work. This paper layer has a basis weight of 200 to 60 used in sake packs and milk packs.
Attach a cardboard of 0 g / m ² . The adhesive layer may be a material such as paper glue or a heat sealant such as polyethylene or hot melt. It is more preferable that the adhesive layer has some heat resistance and water resistance. In particular, the container of the present invention is mainly used for liquids, and the surface of the container may be condensed by refrigeration or ice cooling.Thus, the cardboard is coated with polyethylene lamination, polyolefin wax or paraffin wax on the surface. It is preferably used. Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a perspective view for explaining one embodiment of the present invention, which is partially cut away.

In the present invention, these raw materials are transferred from the inner layer to the outer layer of the container in the order of plastic layer (I) / plastic layer (II) / deposited thin film layer of silicon oxide coated with hydroxyl group-containing thermoplastic resin / paper. This is a liquid paper container mainly made of a blank sheet laminated in the order of layer / adhesive layer / cardboard layer, and made into a box. There is no particular limitation on the container,
It may be a gable top or brick type liquid container. In addition, in the case where contents which are deteriorated by light or the like are particularly contained, an ultraviolet cut film layer or an ultraviolet cut ink layer may be appropriately provided in the blank sheet.

The production of the blank sheet is not limited, but it is convenient to produce it by the following method, for example. That is, first, a silicon oxide thin film layer 2a is formed on one side of a film of the plastic layer (II) by a vacuum deposition method or the like. Next, a hydroxyl group-containing thermoplastic resin is applied to the surface of the silicon oxide thin film layer 2a of this film, and the paper is bonded in a wet state to form a hydroxyl group-containing thermoplastic resin layer 3 and a paper layer 4. Then, an adhesive is applied to the surface of the paper layer to provide an adhesive layer 5, and the cardboard layer 6 is bonded. Finally, the polyethylene layer 1 or the polyethylene layer 1 and the polyethylene layer 7 are formed by coating the low-density polyethylene on the inner surface or both surfaces of the sheet by melt extrusion. In the present invention, it is preferable to provide a polyethylene layer on both sides. The blank sheet thus obtained is prepared in a conventional manner to obtain a liquid paper container. When a container is provided with a spout, if a laminated body mainly composed of a plastic film provided with a silicon oxide thin film layer coated with a hydroxyl group-containing thermoplastic resin at the perforated portion is used, the protection of the contents is further improved. It is possible to do.

[0014]

In the present invention, a thin film layer of silicon oxide is provided in a blank sheet, and a layer coated with a thermoplastic resin containing a hydroxyl group is provided thereon. It has barrier properties equivalent to those of a container made of glass, and furthermore, by providing a hydroxyl group-containing thermoplastic resin layer on the silicon oxide thin film, to improve the brittleness of silicon oxide in addition to its own oxygen gas barrier properties. As a result, the moldability is sufficiently maintained, and it is also possible to bond the paper layer without using special adhesive polyethylene or the like. In addition to the gable-top type according to the present invention, the conventional vacuum-deposited silicon oxide has a sharp bending and is of a brick type that is filled with liquid while being automatically boxed from a winding material that was impossible to be boxed. This blank sheet can be applied to a room temperature storage container. Naturally, since the blank sheet does not use a material that shields microwaves from a microwave oven, such as aluminum foil, it can be directly heated in a microwave oven as it is, and does not damage the furnace material even if it is incinerated. .

[0015]

【Example】

[Example 1] A low-density polyethylene layer 1 / a PET film layer 2 having a thickness of 12 µm 2 / a silicon oxide vapor-deposited layer 2a / a hydroxyl-containing thermoplastic resin (EVOH, Soarnol 30L, Nippon Gohsei Chemical Co., Ltd.) ), Used as a water / isopropyl alcohol solvent of 30% by weight solid)
Layer 3 / paper layer 4 having a basis weight of 50 g / m ² / adhesive layer 5 / basis weight 26
A blank sheet composed of a cardboard layer 6 / a low-density polyethylene layer 7 of 0 g / m ² is applied with a pressure of 50 kg / cm ² using a concave / convex blade having a blade having a shape of 2 mm in width and 1 mm in height. Was manufactured.

[Embodiment 2] In Embodiment 1, EVOH
Gohsenol GL03 instead of (Soarnol 30L)
A liquid paper container was prepared in the same manner as in Example 1 except that (PVA, manufactured by Nippon Synthetic Chemical Co., Ltd.) was adjusted with water so that the polymer concentration became 20% by weight.

[Embodiment 3] In Embodiment 1, the EVOH
Gohsenol GL03 instead of (Soarnol 30L)
(PVA, manufactured by Nippon Synthetic Chemical Co., Ltd.) and Polysol AD-
6 (unsaponifiable EVA, manufactured by Showa Polymer Co., Ltd.)
A / Unsaponified EVA = 2/8 (weight ratio) The same procedure as in Example 1 was carried out, except that a composition prepared by adjusting the solid content concentration to 25% by weight with water was used. Thus, a liquid paper container was prepared.

[Embodiment 4] In Embodiment 1, the EVOH
(Soarnol 30L) instead of Soarnol 30L (EV
OH, manufactured by Nippon Synthetic Chemical Co., Ltd.) and Polysol AD-6
(Unsaponifiable EVA, manufactured by Showa Polymer Co., Ltd.)
H / unsaponifiable EVA = 5/5 (weight ratio), and the composition was mixed with water and isopropyl alcohol at a solid content of 30%.
A liquid paper container was produced in the same manner as in Example 1 except that the liquid paper container was adjusted to be the weight%.

The gas barrier property of the container was measured and its incineration test was conducted. The results are shown in the following table. Gas barrier property: Container 1) Container of the present invention (about 120 g) 2) Conventional container (containing aluminum foil) 3) Container without a hydroxyl-containing thermoplastic resin layer (without aluminum foil, silicon oxide deposited layer No hydroxyl group-containing resin layer is provided.) Contents: Filled with nitrogen (oxygen concentration almost zero) Leave at room temperature after sealing: 3 days

Incineration test: container, same as above (about 120 g × 1
0 pieces) Contents, empty Incineration incinerator

[0021]

The present invention relates to the production of a paper container which can be stored at room temperature because the silicon oxide deposited layer and the hydroxyl group-containing thermoplastic resin layer are used in place of the aluminum foil, so that the heat resistance and the mechanical stress are sufficient. Can manufacture gable-top and brick-type liquid paper containers in the same process as aluminum foil, and facilitate post-treatment (incineration, etc.) of containers.
It has the same barrier properties as conventional liquid paper containers using aluminum foil, and of course, has a very wide range of applications as a food package, including the ability to heat microwave ovens as a pack, and is extremely economical. High liquid paper container.

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view in which a part of one embodiment of the present invention is cut away.

FIG. 2 is an explanatory perspective view in which a part of a conventional liquid paper container is cut away.

[Explanation of symbols]

 Reference Signs List 1 polyethylene layer 2 polyethylene terephthalate (PET) layer 2a silicon oxide thin film layer 3 hydroxyl group-containing thermoplastic resin layer 4 paper layer 5 adhesive layer 6 cardboard layer 7 polyethylene layer A aluminum foil layer B polyethylene terephthalate (PET) layer C polyethylene Layer D Paper layer

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-31849 (JP, A) JP-A-6-218869 (JP, A) JP-A-6-122444 (JP, A) JP-A-6-218444 329153 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B65D 5/00-5/76 B32B 9/00 B32B 27/10 B65D 81/34

Claims (3)

(57) [Claims] 1. A plastic layer (I) / a plastic layer (II) / a silicon oxide vapor-deposited thin film layer coated with a hydroxyl group-containing thermoplastic resin / a paper layer / an adhesive layer / a cardboard layer in order from the inner layer to the outer layer. A container made of liquid paper, which is formed from a blank sheet having a laminated structure mainly composed of a laminated body. 2. The container according to claim 1, wherein the plastic layer (II) is a biaxially oriented polyethylene terephthalate film (PET), a biaxially oriented polyamide film (ON) or a biaxially oriented polypropylene film (OPP). 3. The resin composition according to claim 1, wherein the hydroxyl-containing thermoplastic resin layer is a saponified ethylene-vinyl acetate copolymer and / or polyvinyl alcohol or a resin composition obtained by blending the saponified ethylene-vinyl acetate copolymer with them. 3. The container made of liquid paper according to 1 or 2.