JP4194349B2 - Package sealed with a ring seal with heat-sealing lid - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a package in which a polypropylene container that contains food such as dairy products, confectionery, and prepared foods, beverages, and medicines is ring-sealed with a lid.
[0002]
[Prior art]
Conventionally, as a lid for a polypropylene resin container, an aluminum foil is laminated with a heat adhesive resin such as an acid-modified polypropylene resin, a chlorinated polypropylene resin, or an ethylene-vinyl acetate copolymer resin via a polyolefin resin layer or the like. In many cases, when a modified polypropylene resin is used, the opening strength is remarkably increased depending on the thermal bonding temperature, which may make it difficult to open with fingers. In addition, when an ethylene-vinyl acetate resin is used, there is a problem that the thermal adhesive strength is greatly reduced particularly when sterilization with hydrogen peroxide is performed. Furthermore, the cover material of the conventional configuration has a relatively high cost of raw materials, and has caused an economical inconvenience as a cover material that is assumed to be disposable.
[0003]
[Problems of the Invention]
Accordingly, an object of the present invention has a proper degree of thermal bonding strength, can open smoothly with fingers, without thermal bonding strength decreases in sterilization with hydrogen peroxide, can be ring seal in a wide temperature range It is to provide a package using a heat-sealing lid formed from a low-cost raw material.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention comprises at least an aluminum foil and a thermal adhesive layer obtained by adding 50 wt% or less of an acrylic resin to a styrene-butadiene copolymer resin provided on one surface thereof. The heat sealing lid material in which the resin is one of styrene-acrylic acid copolymer, styrene-methacrylic acid, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer or polymethacryl styrene is hydrogen peroxide. After the sterilization treatment with water, the package was formed by ring-sealing the opening of the polypropylene container at a temperature of 120 to 250 ° C.
The thermal adhesive layer is preferably formed from a blend resin in which 97 to 50% by weight of a styrene-butadiene copolymer resin and 3 to 50% by weight of an acrylic resin are mixed, and the thickness is preferably 1 to 15 μm.
[0005]
Embodiment
Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the heat sealing lid material 1 is composed of a laminate in which a heat bonding layer 3 is provided on one surface of an aluminum foil 2 and an exterior material 4 is provided on the other surface.
[0006]
The aluminum foil 2 may be a pure aluminum foil or an aluminum alloy foil. Pure aluminum (JIS (AA) 1000 series, for example, 1N30, 1N70, etc.), Al-Mn series (same 3000 series, for example, 3003, 3004) Etc.), Al-Mg-based (5000-based), Al-Fe-based (8000-based, for example, 8021, 8079, etc.) materials can be used. In addition, about components, such as Fe, Si, Cu, Ni, Cr, Ti, Zr, Zn, Mn, Mg, and Ga, if it is in the range of the well-known content prescribed | regulated by JIS etc., it does not interfere. The thickness of the aluminum foil 2 is preferably about 10 to 80 μm, more preferably 20 to 60 μm. If the thickness is less than 10 μm, the probability of occurrence of pinholes increases and the strength as a packaging material may be insufficient. On the other hand, when it exceeds 80 μm, flexibility as a packaging material becomes poor and it is not desirable from the viewpoint of economy. Moreover, it is preferable that the aluminum foil 2 is a semi-hard material or a soft material, and it is desirable that the aluminum foil 2 is subjected to at least one heat treatment (usually 200 to 500 ° C.) after rolling. By using the aluminum foil 2 as described above, the effects of the present invention can be sufficiently exhibited, and the versatility, barrier properties, light shielding properties, and reliability as packaging materials can be provided. If necessary, the aluminum foil 2 can be molded, degreased / cleaned, printed / colored, overcoated, surface-treated, and the like by a known method.
[0007]
The thermal adhesive layer 3 is preferably composed of a styrene-butadiene copolymer resin as a main component and an acrylic resin added thereto in an amount of 50% by weight or less. The blending ratio of the styrene-butadiene copolymer resin and the acrylic resin is preferably 3 to 50% by weight of the acrylic resin with respect to 97 to 50% by weight of the styrene-butadiene copolymer resin. By adding the acrylic resin within this range, it is possible to obtain a more appropriate thermal bond strength and to impart smooth opening with fingers. If the blending amount of the acrylic resin exceeds 50% by weight, the thermal adhesive strength is unnecessarily lowered, and the sealing and reliability may be impaired, which is not preferable. Examples of acrylic resins include styrene-acrylic acid copolymers, styrene- (meth) acrylic acid, styrene-acrylic acid ester copolymers, styrene- (meth) acrylic acid ester copolymers, and poly (meth) acrylic styrene. Is mentioned. By adding a suitable organic solvent such as toluene, MEK (methyl ethyl ketone), ethyl acetate or the like to a styrene-butadiene copolymer resin alone or an acrylic resin, and directly coating the aluminum foil with a known method. The lid member 1 of the present invention can be obtained. The application method is not particularly limited, and any method such as a gravure roll coater, a roll coater, or spray application may be used. The thickness of the heat bonding layer 3 is preferably about 1 to 15 μm after drying. If it is less than 1 μm, sufficient thermal adhesive strength cannot be obtained, and the sealing performance and reliability may be impaired. On the other hand, if it exceeds 15 μm, the cost may be increased and the easy-openability may be reduced.
[0008]
An exterior material 4 may be laminated on the outer surface of the aluminum foil 2. As the exterior material 4, a resin film, paper, or the like can be used. Of course, an arbitrary layer may be provided with an anchor coat layer, a printing / coloring layer, a primer layer, an overcoat layer, or the like as required. For the paper layer, pure white roll paper, kraft paper, fine paper, imitation paper, western paper, Japanese paper, various coated papers, and the like can be used, and the thickness of the paper is suitably 30 to 150 μm, preferably about 50 to 130 μm. When a paper layer is used, curling of the cover material 1 is prevented, the cover material 1 is given adequate rigidity to reduce troubles during sheet feeding, and dead-holding properties (shape retention after opening) when opened ).
[0009]
When a resin film is used as the packaging material 4, for example, a resin film having a thickness of 9 to 50 μm, specifically, polyamide (nylon), high-density polyethylene, stretched polypropylene, PEN (polyethylene naphthalate), PET (polyethylene terephthalate), etc. 1 type (s) or 2 or more types can be used. Of these, the use of a polyamide-based resin (nylon) or a polyester-based resin is particularly preferable. Adoption of the resin film is useful in terms of improving the strength of the lid member 1 and also providing puncture resistance, water resistance, tear resistance, and the like.
[0010]
The method for laminating and adhering between the layers 2, 3, and 4 is not particularly limited, and a known method such as a dry / urethane type adhesive using a two-component curable urethane adhesive such as a polyester urethane type or a polyester type can be used. Lamination, coextrusion, extrusion coating, thermal lamination using an anchor coating agent, or the like can be employed.
[0011]
As a container using the lid material 1 of the present invention, a polypropylene resin container is suitable, and a PET container is not suitable. What has the flange part for heat sealing in the opening part of a container is desirable. In addition, although the conditions of heat sealing are based also on the structure and thickness of the cover material 1, it is 120-250 degreeC normally, Preferably it is about 0.3-5.0 second at 160-240 degreeC. The lid material 1 of the present invention is particularly suitable for a container that is ring-sealed (heat-sealing the lid material to a flange portion of a synthetic resin container in a concave or convex cross section), and the width of the concave or convex portion. A depth of 0.3 to 3 mm, a depth of the concave portion or a height of the convex portion of 0.1 to 0.5 mm is preferable. Note that the bottom surface and the wall surface of the concave portion of the ring seal may not be completely straight, but may be gently curved or inclined, and the corners may be rounded even if they are not perfect corners. By providing such a ring seal, the sealing performance is further improved.
[0012]
Examples and Comparative Examples
Each thermal adhesive shown in FIG. 2 was applied to a matte surface of a soft aluminum foil (1N30) having a thickness of 50 μm at a dry weight of 5 g / m ² (thickness after drying: about 5 μm) to prepare a lid material. After drying, a ring seal (ring width of 1 mm is recessed in the opening flange of a polypropylene 71 mmφ × 50 mm (height) container with a heat seal temperature of 180, 210, 240 ° C., a heat sealer head pressure of 100 kg / cup, and a seal time of 1 second. ) To obtain a package. Thereafter, an opening angle (a sandwich angle) of 45 ° and an opening speed of 300 mm / min. Then, the opening strength of the lid was measured. In addition, after the preparation of each lid material, on the premise of sterilization packaging, after sterilization by hydrogen peroxide solution H ₂ O ₂ (30 wt% concentration, 70 ° C. × 1 minute immersion) treatment, a package is produced in the same manner as described above. Similarly, the results of measuring the opening strength are shown in FIG. In addition, although the same test was tried with respect to the container made from PET instead of the said container made from polypropylene, sufficient opening strength was not obtained. In FIG. 2, SB represents a styrene-butadiene copolymer resin, and SA represents a styrene-acrylic acid copolymer resin. Moreover, (circle) shows what has moderate heat bond strength, and can be opened easily with a finger | toe, and x shows what has the defect shown in a comment, respectively.
[0013]
【effect】
The package of the present invention has the advantages listed below.
1 . The lid material has moderate thermal adhesiveness to polypropylene containers, and has both sealing performance, reliability, and openability.
2 . Even after sterilization with hydrogen peroxide solution or the like, the lid material maintains appropriate thermal adhesiveness and has a small heat seal temperature dependency.
3 . It can be manufactured in a simple process and is excellent in versatility, mass productivity, and productivity.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a lid material. FIG. 2 is a table showing test results of examples and comparative examples.
1 Lid material 2 Aluminum foil 3 Thermal bonding layer 4 Exterior material

Claims (3)

  It comprises at least an aluminum foil and a thermal adhesive layer in which an acrylic resin is added to 50% by weight or less of a styrene-butadiene copolymer resin provided on one side thereof. The acrylic resin is a styrene-acrylic acid copolymer, styrene- After sterilizing the heat sealing lid material which is either methacrylic acid, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer or polymethacryl styrene with hydrogen peroxide, at a temperature of 120 to 250 ° C. A package with a ring seal at the opening of a polypropylene container.   The package according to claim 1, wherein the thermal adhesive layer is made of a blend resin in which 97 to 50% by weight of a styrene-butadiene copolymer resin and 3 to 50% by weight of an acrylic resin are mixed.   The package according to claim 1 or 2, wherein the thickness of the thermal adhesive layer is 1 to 15 µm.

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