JPH06255042A - Composite paper for food container and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an excellent adhering and printing property without decreasing taste and sweet smell by giving a plasma treatment through flame at a specific output value onto a cardboard that consists of a cardboard and a synthetic resin laminated layer and is in the range of a specific basis weight. CONSTITUTION:The composite paper for food containers comprises a cardboard and synthetic resin laminated layer, and the cardboard used herein has a basis weight of 100-150 g/m<2> in terms of a shape retaining property and mold-working property. The quality of material of the cardboard is arbitrarily selected in accordance with use or the like. For the synthetic resin, polyolefine or polyester resin is employable, however, a low density polyethylene is preferably used by taking into consideration work execution characteristics, a heat sealing property or the like. After obtaining a composite paper by combining a cardboard and synthetic resin, a flame plasma treatment is given so that the flame combustion energy is to be 9-47 BTU/m<2> against the treatment surface of the cardboard. As a consequence of this process, the Indexes of adhesiveness between the cardboard and the synthetic resin, and surface leakage of the synthetic resin can be enhanced, and still the improvement of a smell or taste can be achieved as a beverage container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite paper for food containers, which is a composite paper container laminated with a synthetic resin film in food, particularly a liquid food paper container, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, liquid food containers have been converted from bottles, cans, plastic bottles and the like into composite paper containers laminated with a synthetic resin film because the waste can be easily incinerated. In addition, the composite paper container has many advantages such as light weight, easy heat sealing, and low cost, but on the other hand, the contents have a peculiar odor and a bad taste. It also has drawbacks such as In particular, mineral water, juice, milk, liquor and the like containers are currently used with these drawbacks.

The composite paper for liquid containers is generally manufactured by a method of extrusion-laminating a synthetic resin on the paper. In order to improve the adhesiveness between the paper and the synthetic resin during the laminating process, corona discharge is used. Treatment and ozone spraying are being performed.

[0004]

However, when a paper container is made using the composite paper for liquid containers obtained by performing these treatments and mineral water, juice, milk, liquor, etc. are enclosed, a glass bottle or a PET bottle. At present, the odor and flavor are inferior to those in the case where they are enclosed in, for example. Possible causes of deterioration of odor and flavor are thermal decomposition products of synthetic resin at high temperature extrusion, corona discharge and ozone or oxidation products of synthetic resin generated by these, and further emission from paperboard as a base material. Volatile substances, etc. are considered, and it is required to reduce these effects as much as possible.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve these drawbacks, the inventors of the present invention have improved the adhesiveness between paper and synthetic resin and / or the printability of synthetic resin with frame plasma. The inventors have found that a container made of composite paper improved by treatment can solve the above problems all at once, and arrived at the present invention. That is, the first of the present invention is a composite paper for food containers, which comprises a paperboard and a synthetic resin laminate layer,
For basis weight of the paperboard is in the range of ^{100g / m 2 ~500g / m 2} , and the improvement of wettability index of adhesion improvement and / or synthetic resin laminate layer of paperboard and plastic laminate layer, said paperboard The flame output is 9 BTU /
food containers composite sheet, characterized in that subjected to flame plasma treatment with m ² ~47BTU / m ^2, the of the present invention 2
, Upon extrusion lamination of synthetic resin board, a basis weight using a board range of ^{100g / m 2 ~500g / m 2} , and the improvement of adhesion between the board and the synthetic resin laminate layer and / or the synthetic resin laminate In order to improve the wetting index of the layer, the flame output of the paperboard is 9 BTU / m 2 against the treated surface.
^A method for producing a composite paper for food containers, characterized by performing a flame plasma treatment at ^{2 to} 47 BTU / m ² , respectively.

The synthetic resin used in the present invention is preferably a polyolefin-based resin, a polyester-based resin or the like. Examples of the polyolefin-based resin include low-density polyethylene, a copolymer thereof, a medium-density polyethylene or a copolymer thereof, Examples thereof include high-density polyethylene or its copolymer, polypropylene or its copolymer, and 4-methylpentene-1, and examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, and modified products thereof. These are single or 2
Used in combination of two or more species. Among these, low density polyethylene is particularly preferable in terms of workability, heat sealability, economy and the like. These synthetic resins are extruded by an ordinary extruder and laminated, but the extruding temperature may be arbitrarily selected depending on the processing conditions and the like. That is, in the case of a polyolefin resin, a temperature range of 280 ° C to 320 ° C is general,
In the case of a polyester resin, 260 ° C to 300 ° C is suitable.

[0007] The paperboard used in the present invention, the basis weight used in the range of ^{100g / m 2 ~500g / m 2} . If it is less than 100 g / m ² , the shape retention of the container is poor, and if it exceeds 500 g / m ² , the moldability of the container is significantly deteriorated. More preferably, the basis weight is 200 g / m ² to 4
00 g / m ² . Further, the material of the paperboard may be appropriately selected depending on the application, etc., but a material having a strong odor is not preferable.

Next, flame plasma treatment is performed to improve the adhesiveness between the paperboard and the synthetic resin. In this case, flame burning energy of flame plasma is 9B to the paperboard treated surface.
It is necessary to be TU / m ^{2 to} 47 BTU / m ² . If the flame burning energy is less than 9 BTU / m ² , the adhesive strength between the paperboard and the synthetic resin will be below the practical strength,
Almost no improvement in the wetting index on the surface of the synthetic resin was observed, and at the same time, the problem of odor and flavor of the obtained composite paper as a liquid container was not sufficiently improved. On the other hand, even if the flame burning energy of flame plasma exceeds 47 BTU / m ² ,
The above-mentioned effects of improving the adhesiveness and surface wetting index, and further improving the odor and flavor are not so improved despite the energy consumption, and there is a problem that the base material is easily damaged.

That is, when the flame burning energy of flame plasma is in the range of 9 BTU / m ^{2 to} 47 BTU / m ² , the adhesiveness between the paperboard and the synthetic resin, the improvement of the surface wetting index of the laminated synthetic resin, and the synthesis of the paperboard. Very good results are obtained in improving the odor and flavor of a liquid container of a composite paper obtained by laminating a resin.

The composite paper obtained by the present invention can be suitably used as a food paper container by using it for liquid food and drink such as fruit juices, mineral water, milk and alcohol. Of course, the composite paper for food containers of the present invention, in addition to liquid food and drink, fluid, paste, semi-solid, etc., further reduction of odor and flavor, it is necessary to avoid deterioration of flavor due to moisture. It is also suitable for some solid and powdery materials.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 4 and Comparative Examples 1 to 3 As shown in Table 1, a paperboard was used, and various synthetic resins were extruded from the T-die extruder under a predetermined temperature condition and laminated. At this time, in order to bond the paperboard and various synthetic resins, a predetermined amount of pretreatment is performed using flame plasma (made by Flinburner), corona (made by Sophtal), and ozone (made by Sophtal), and the synthetic resin Was laminated to complete the lamination on the liquid contact surface side. Then, the opposite surface (printing surface) is similarly subjected to a predetermined amount of pretreatment to laminate a synthetic resin, and the above-mentioned flame plasma for further improving printability (evaluated by a wetting index) on the laminated surface, Post-treatment with corona and ozone was performed to produce a composite paper for food containers. About these synthetic resin laminated composite papers, heat sealability (heat sealer manufactured by Shiga Packing Machine Co., Ltd.), wetting index, odor,
A pack test was performed to evaluate the flavor. In the pack test, these composite papers were cut into A4 size, folded in half, and heat-sealed at both ends with the heat sealer to form a bag, in which mineral water (commercially available Rokko water) and sake (Ozeki / registered trademark) were added. , Bottle milk (manufactured by Morinaga Milk Industry Co., Ltd.) orange juice (Barriers, registered trademark) 40
Then, the upper part was heat-sealed and placed in a home refrigerator for 24 hours for storage.

The stored samples as described above were used as test objects in the pack test, and tasted by five experienced panelists, and the odor and flavor of each were evaluated. As for the evaluation result, the average evaluation of 5 persons was evaluated in three grades of ◯, Δ, and ×. ○ is 5
Most of the panelists judged that the odor and flavor were good,
X indicates that most of the five panelists felt an offensive odor in the odor and flavor and judged that the flavor was inferior, and Δ indicates an evaluation that was an intermediate judgment between these. From the results of Table 1, olefin resin,
It can be seen that the polyester resin that has been subjected to flame plasma treatment has sufficient heat sealability and wetting index, and also has a good odor and flavor in the pack test, as compared with those that have been subjected to corona and ozone treatment. . Also, flame plasma is not practical when the flame energy is 8 BTU / m ² and it is not practical, and when the paper as the base material is less than 100 g / m ² , the moldability as a container is insufficient. It was

[0014]

[Table 1]

The contents and manufacturers of the products in Table 1 are as follows: M-16: Low-density polyethylene Mitsui Petrochemical Industry Co., Ltd. UZ15100C: Linear low-density polyethylene Mitsui Petrochemical Industry Co., Ltd. LA- 221: Polypropylene Mitsui Petrochemical Co., Ltd. Sealer PT: Modified polyester Mitsui DuPont Polychemical Co., Ltd. Novamid 1020CA: Mitsubishi Rayon Co., Ltd.

Example 5 Among composite papers for food containers, paperboards laminated with aluminum foil were used. That is, the aluminum surface of an aluminum foil film obtained by laminating a 24 μm thick polyethylene (M-16 manufactured by Mitsui Petrochemical Co., Ltd.) on a 9 μm thick aluminum foil (made by Sumitomo Light Metal Industries, Ltd.) and the paperboard of Example 1. And synthetic resin (M-1 manufactured by Mitsui Petrochemical Industry Co., Ltd.
At the time of laminating by the extrusion laminating method of 6), flame plasma treatment was performed in the same manner as in Example 1 to prepare a composite paper in which an aluminum foil was laminated on the liquid contact surface side. The printed surface side was also subjected to flame plasma treatment in the same manner as in Examples 1 to 4 and Comparative Examples 1 to 4 to improve the wetting index. Then, Example 1
4 and Comparative Examples 1 to 4, quality evaluation was performed.
The odor and flavor evaluations by the pack test were good.

Comparative Example 5 In Example 5, the same operation as in Example 5 was performed except that the corona treatment was applied instead of the flame plasma treatment, and the same evaluation was performed. The evaluation by the pack test was significantly inferior to that in Example 5.

[0018]

INDUSTRIAL APPLICABILITY As described above, the present invention can provide a composite paper for food containers, which does not reduce the flavor and odor (fragrance) of the contents and has good adhesiveness and / or printability.

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Claims (3)

[Claims] 1. A composite paper for food containers comprising a paperboard and a synthetic resin laminate layer, wherein the paperboard has a basis weight of 100 g / m.
It is in the range of ^{2 to} 500 g / m ² , and in order to improve the adhesiveness between the paperboard and the synthetic resin laminate layer and / or the wetting index of the synthetic resin laminate layer, the flame output of the paperboard against the treated surface A composite paper for food containers, which is subjected to flame plasma treatment at 9 BTU / m ^{2 to} 47 BTU / m ² . Upon wherein extrusion laminated paperboard synthetic resin, using a board range basis weight of 100 g / m ² to 500 g / m ^2, and the improvement of adhesion between the board and the synthetic resin laminate layer and / or In order to improve the wetting index of the synthetic resin laminate layer, the flame output of the paperboard was 9% with respect to the treated surface.
BTU / m ² ~47BTU / m the preparation of food containers composite sheet, characterized in that applying the flame plasma treatment with ^2. 3. The method according to claim 2, wherein the synthetic resin is a polyolefin synthetic resin and / or a polyester synthetic resin.