JP2005041539A - Packaging material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging material which can almost completely be heat-sealed, and is excellent in re-cohesion, and a lid member of which the processing is easy. <P>SOLUTION: For this packaging material for heat-sealing, an adhesive layer is formed on one surface of a base material, and in addition, a heat-seal agent layer is formed on the top of the adhesive layer. A bonding strength between the adhesive layer and the heat-seal agent layer is smaller than a heat-seal strength between the seat-seal agent layer and a layer which becomes the objective for heat-sealing. As the adhesive, one which includes a hydrogenation object of a random copolymer comprising 1 to 50 mass% of styrene, and 99 to 50 mass% of a diene-based hydrocarbon is preferable. As the heat-seal agent, a lacquer type one is preferable. This packaging material is suitable for the application as a lid member or a packaging bag. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a re-adhesive packaging material.

  Many containers such as cups have a sheet-like lid heat-sealed. However, the heat-sealed product cannot be bonded again if the consumer peels it off. Therefore, when storing a part of the contents, it is necessary to wrap the entire container with a wrap or the like, which is extremely inconvenient.

  As a technique for solving this problem, a packaging material in which a heat seal layer is formed on a base material and a layer capable of re-adhesion is formed thereon or a layer having heat sealability and re-adhesion property at the same time is formed is known. (Patent Document 1). However, when a re-adhesive layer is formed on the heat seal layer, the re-adhesion layer is not completely eliminated at the time of heat sealing, and the heat sealing may be incomplete. In the case of forming a layer having heat sealability and re-adhesiveness at the same time, separation of the container and the lid may be difficult when the heat seal is completed.

Patent Document 2 discloses a cover material composed of an outer resin layer, an adhesive resin intermediate layer, and an inner heat-seal resin layer. However, this lid material has a problem that an easy opening process part must be provided along the heat seal part in the inner heat seal resin layer, and the processing process becomes complicated.
JP 2003-112768 A JP 11-171250 A

  An object of the present invention is to provide a packaging material that can be almost completely heat-sealed and has excellent re-adhesiveness. Another object of the present invention is to provide a lid material that is easy to process.

The present inventor conceived that the above object can be achieved by appropriately adjusting the interlayer adhesive strength between the pressure-sensitive adhesive layer and the heat sealant layer and the heat seal strength between the heat sealant layer and the layer to be heat sealed. The present invention has been completed.
That is, the present invention is as follows.
1. A heat-sealing packaging material in which a pressure-sensitive adhesive layer is formed on all or part of at least one surface of a substrate, and a heat-sealant layer is formed on all or part of the pressure-sensitive adhesive layer. A packaging material in which the adhesive strength between the pressure-sensitive adhesive layer and the heat-sealant layer is smaller than the heat-seal strength between the heat-sealant layer and the layer to be heat-sealed.
2. 2. The packaging material according to 1 above, wherein the pressure-sensitive adhesive comprises a hydrogenated product of a random copolymer comprising 1 to 50% by mass of styrene and 99 to 50% by mass of a diene hydrocarbon.
3. The packaging material according to 1 or 2, wherein the heat sealant is a lacquer type.
4). A cover material having re-adhesiveness comprising the packaging material of 1, 2 or 3 above.

  The packaging material of the present invention has excellent heat seal strength and can be easily re-adhered even after being peeled off. Moreover, when using as a cover material of a container, it is not necessary to provide an easy-sealing part and manufacturing is easy. Moreover, it can be used not only as a lid but also as a packaging material such as a bag.

The present invention will be described in detail below. In the present invention, heat sealing is not limited to heat sealing in a narrow sense that uses heat conduction to heat and bond, but also heat sealing such as ultrasonic sealing and high frequency sealing. All items to be sealed shall be included.

  In the present invention, the adhesive strength between the heat sealant and the heat sealant layer is such that the interlayer adhesive strength between the heat sealant layer and the heat sealant layer is relatively smaller than the heat seal strength between the heat sealant layer and the layer to be heat sealed. Select the agent. In particular, the selection of the adhesive is important.

  Examples of such a pressure-sensitive adhesive include a hydrogenated random copolymer composed of 1 to 50% by mass of styrene and 99 to 50% by mass of a diene hydrocarbon. Preferably, the melt flow index according to ASTM D1238 (230 ° C., 2.16 kg) is 2 to 10. Examples of diene hydrocarbons include butadiene and isoprene. Examples of the hydrogenated product of such a styrene / diene random copolymer include DYNARON (registered trademark) HSBR series manufactured by JSR Corporation. Such a random copolymer hydrogenated product of styrene and diene hydrocarbon, once adhered and then peeled off, the adhesive strength does not change much even if it is stuck again, and repeated sticking and peeling. It can be carried out. The hydrogenated styrene / diene random copolymer may be modified with a blend of polyolefin resin or the like. Examples of the polyolefin resin include polyethylene, polypropylene, a copolymer of ethylene and α-olefin, an ethylene-methyl (meth) acrylate copolymer, and an ionomer. The ratio of the hydrogenated styrene / diene random copolymer and the polyolefin resin is preferably 100 to 60: 0 to 40 by mass ratio.

  The resin used as the heat seal layer is preferably a so-called heat seal lacquer. The heat seal lacquer is a coating type heat seal agent, and examples thereof include non-solvent type or solvent type emulsions, suspensions, and solutions of heat sealable resins such as acrylic resins and vinyl acetate resins. . If a heat seal lacquer is used, the strength of the heat sealant layer itself is not large and the layer can be formed thin. Therefore, when used as a container lid, it is not necessary to provide a special easy opening portion. Cutting at the boundary of the heat seal part facilitates opening.

  As the substrate in the present invention, a sheet of paper, plastic, metal or the like, a film, a foil, or the like is used. Examples of the plastic include polyester, polyethylene, polypropylene, and nylon. The substrate may be a laminated material. For example, laminated materials such as different plastics, plastic and aluminum foil, and plastic and paper can be used, but the present invention is not limited thereto. Moreover, vapor deposition, such as aluminum, may be given to the base material.

The packaging material of the present invention can be produced, for example, as follows.
First, an adhesive resin is extruded and laminated on the entire surface or a part of a substrate sheet, film, foil, or the like. Next, a so-called heat seal lacquer is coated on the surface of the adhesive resin layer. The heat seal lacquer may be coated only on the portion requiring heat seal.
The above method is an example, and any method may be used.

  The material to be bonded to which the packaging material of the present invention is bonded, for example, the material of the container is not limited as long as it can be heat sealed by a heat sealant, polyolefin resin such as polypropylene and polyethylene, modified polyolefin resin, polystyrene, rubber-modified polystyrene, Examples thereof include a styrene resin such as an ABS resin, or a laminated material using one or more of these. Styrenic resins are preferred.

FIG. 1A is a cross-sectional view of a container using the lid of the present invention, and FIG. 1B is a cross-sectional view of a state where a part of the lid is peeled from the container.
In the figure, a pressure-sensitive adhesive layer 12 is formed on a substrate 11 of a lid 1, and a heat seal lacquer agent layer 13 is formed on the pressure-sensitive adhesive layer by coating or the like. In the figure, the thickness of the base material, the pressure-sensitive adhesive, and the coating agent layer is drawn to be almost equal for easy understanding, but the thickness of the coating agent layer is actually very thin at about 0.5 to 10 μm. The lid 1 is heat sealed to the flange portion 3 of the container 2. A tab 4 is formed on the lid, and when the tab is pinched and pulled, peeling occurs at the interface between the pressure-sensitive adhesive layer and the heat sealant layer as shown in FIG. When the peeled lid is put on a container and pressure-bonded with a finger or the like, the pressure-sensitive adhesive layer re-adheres to the flange portion and can be sealed again. Thereafter, peeling and adhesion can be repeated.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by these.
Example 1
Random copolymer hydrogenated product comprising 10% by mass of styrene and 90% by mass of diene hydrocarbon as an adhesive on the OPP surface of a laminate film (thickness 50 μm) of polyester (PET) and biaxially oriented polypropylene (OPP) (JSR Corporation DYNARON 1320P, melt flow index 3.5) was laminated to a thickness of 25 μm by extrusion lamination using a T-die. Subsequently, a solvent-soluble acrylic heat seal lacquer (Dick Seal A415-3, manufactured by Dainippon Ink Chemical Co., Ltd.) was coated to obtain a lid material.
This lid material was cut out into a circle with a tab and heat-sealed into a polystyrene container having an inner diameter of 80 mm and a flange width of 5 mm as shown in FIG. The sealing conditions are a temperature of 200 ° C., a pressure of 245 kPa, and a time of 1 second.
The initial opening strength and reopening sealing strength of the lid were measured with a tensile tester. The resealing strength was defined as the opening strength after the lid material once opened and peeled was again pressure-bonded to the container at room temperature and adhered. The measurement was performed by sandwiching the tab of the lid material between the chuck of the testing machine and pulling it at a speed of 100 mm / min, and measuring the strength at the opening start point, the center portion, and the opening end point.
The results were as follows.
Initial opening strength: 15.23N (opening start point), 3.33N (center), 14.70N (opening end point)
Opening strength after re-sealing: 2.25N (opening start point), 0.44N (center), 1.76N (opening end point)

Comparative Example 1
An acrylic heat seal lacquer was directly coated on the surface of the OPP of the same film as in Example 1 to obtain a lid.
The container was heat sealed in the same manner as in Example 1 to measure the initial opening strength. The lid did not re-adhere and was not resealable.

  Since the packaging material of the present invention is excellent in re-adhesiveness, it is very useful as a container lid or packaging bag that needs to be sealed again after being opened once.

FIG. 1A is a cross-sectional view of a container using the lid of the present invention, and FIG. 1B is a cross-sectional view of a state where a part of the lid is peeled from the container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lid 2 Container 3 Flange part of container 4 Tab of lid 11 Base material 12 Adhesive layer 13 Heat seal agent layer

Claims (4)

  A heat-sealing packaging material in which a pressure-sensitive adhesive layer is formed on all or part of at least one surface of a substrate, and a heat-sealant layer is formed on all or part of the pressure-sensitive adhesive layer. A packaging material in which the adhesive strength between the pressure-sensitive adhesive layer and the heat-sealant layer is smaller than the heat-seal strength between the heat-sealant layer and the layer to be heat-sealed.   2. The packaging material according to claim 1, wherein the pressure-sensitive adhesive comprises a hydrogenated product of a random copolymer comprising 1 to 50% by mass of styrene and 99 to 50% by mass of diene hydrocarbon.   The packaging material according to claim 1 or 2, wherein the heat sealant is a lacquer type.   A lid material having re-adhesiveness comprising the packaging material according to claim 1, 2 or 3.

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