JPH0131473Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a transparent film that can be heat-sealed at low temperatures.

Conventionally, emulsions have been known that are made by dispersing a modified ionomer, which is made by copolymerizing an ionomer with a styrene monomer and a (meth)acrylic acid ester monomer, in a suitable solvent.This emulsion is coated on a suitable sheet and dried. It was known that the resulting film could be heat-sealed at a low temperature of about 46-89°C. This emulsion is, for example, commercially available from Mitsui Petrochemicals Co., Ltd. under the trade name Chemipearl, and because of its low-temperature heat-sealing properties, it can be used to heat packaging materials used to package contents that are susceptible to heat-sealing, such as chocolate and frozen desserts. It was useful as a sealant.

However, when this emulsion is applied to paper or metal foil such as aluminum foil and dried, it forms a film that has strong adhesion to these sheets. When applied to a base and dried, the resulting film has an impractical level of adhesion. For this reason, when this emulsion is used as a packaging material, the base sheet must be opaque, such as paper or metal foil, so the contents cannot be seen through, and the printed image cannot be seen on the surface of the packaging material.
In other words, there was no other way than applying it to the outside surface.
From the viewpoint of abrasion resistance, it is preferable to apply the printed image to the inner surface of the packaging material.

The present invention was developed in view of these circumstances, and consists of using a transparent film as a base sheet, applying a printed image on the back side corresponding to the inside of the packaging material, and furthermore, this film has a film obtained from the emulsion mentioned above. The purpose is to provide a film with strong adhesive strength.

That is, in the present invention, as shown in the cross-sectional view of FIG. 1, after a printed image 2 is applied to the back side of a transparent film 1, a transparent paint containing a mixed resin of polyvinyl chloride and polyurethane is applied to the entire printed image surface. Apply 3 and add styrene monomer (meta) to the ionomer.
This is a transparent film that can be heat-sealed at low temperatures by applying an emulsion 4 whose main component is an acrylic acid ester monomer or a modified ionomer obtained by copolymerizing both of them and drying it.

In this invention, the base transparent film 1
For example, stretched or unstretched polypropylene film, polypropylene film coated with vinylidene chloride on the surface, polyester, nylon, cellophane coated with or without vinylidene chloride on the surface, or these can be heat-fused or bonded. Laminated films laminated with adhesive can be used.

Further, the printed image 2 may be made of any printing ink, but from the viewpoint of adhesion with the transparent paint 3, a mixed resin of polyvinyl chloride and polyurethane is used as the resin component, and coloring agents such as pigments and dyes are added to this. It is preferable to use a printing ink dissolved in a suitable solvent, with other additives added as necessary. Although printing may be performed by any method, gravure printing is generally used.

Further, as described above, the resin component of the transparent paint 3 is a mixed resin of polyvinyl chloride and polyurethane.
As the polyurethane in the transparent material 3 or the polyurethane in the printed image 2, moisture curing one-component polyurethane or two-component curing polyurethane can be used. There are Takera Tsuku manufactured by Takeda Pharmaceutical Co., Ltd., and the latter include Lamiace manufactured by Toyo Ink Manufacturing Co., Ltd. and Panacea manufactured by Dainippon Ink Manufacturing Co., Ltd.

Emulsion 4 is mainly composed of a modified ionomer obtained by copolymerizing an ionomer with a styrene monomer, a (meth)acrylic acid ester monomer, or both, and is made into a latex by dispersing it in an appropriate solvent and drying it. The subsequent coating can be heat sealed or heat fused at low temperatures, e.g. 46-89°C. The ionomer may be any one such as a copper-based one or a sodium-based one.As the (meth)acrylic acid ester monomer, methyl (meth)acrylate, ethyl (meth)acrylate, etc. can be used, but among them, butyl (meth)acrylate can be used. Acrylates are preferred. Chemipearl manufactured by Mitsui Petrochemical Co., Ltd. is an example of such a latex-like emulsion, but in order to prevent blocking during storage after application, a wax may be further added and mixed. In addition to waxes made of higher fatty acid esters, there are so-called polyethylene waxes (higher paraffin), and when an emulsion containing this wax is applied, these waxes bleed onto the surface of the film when it dries. , blocking can be prevented without impairing its low-temperature heat-sealability.

This emulsion 4 may be applied by any method, but it is applied by so-called direct coating, that is, by rotating a roll immersed in the emulsion and bringing the film, which is the material to be coated, into direct contact with this roll. be able to. Of course, one or more rotating rolls may be interposed between this roll and the film to be printed to adjust the coating thickness.

The present invention will be explained below with reference to Examples.

<Examples and Comparative Examples> Stretched polypropylene film was coated with 5 parts by weight of isopropyl alcohol per 100 parts by weight of Chemipearl (modified ionomer made by copolymerizing ionomer with styrene monomer and n-butyl acrylate monomer) manufactured by Mitsui Petrochemical Co., Ltd. Sample A was prepared by mixing 1 part by weight, 4 parts by weight of petroleum wax, and 0.8 part by weight of higher fatty acid amide.

In addition, on the same stretched polypropylene film, we applied ink and transparent paint containing polyvinyl chloride as the resin component, ink and transparent coating composition containing polyurethane as the resin component, and ink and transparent coating composition containing a mixture of polyvinyl chloride and polyurethane as the resin component. After printing and coating, drying and winding, the samples were left to stand for two days, and the above Chemipearl paint was applied to give Samples B, C, and D, respectively. In addition, sample C showed severe blocking during the two days after being applied with the polyurethane paint, and a good film could not be obtained.

These samples A, B, C, and D were stacked on top of each other and heated at 80 to 85°C and 1 kg/m ² .
Heat sealing was performed for 0.5 seconds, and the peel strength in T-peel was measured. Note that this peeling surface was the surface of the polypropylene film or between the heat-sealed paint/paint. The results are 0g/15mm for sample A and 150-250g/15mm for sample B.
mm, samples C and D were 250 to 400 g/15 mm.

As described above, Sample D according to the present invention firmly adheres to the modified ionomer, like Sample C whose resin component is only polyurethane, and does not cause blocking after application.

The present invention is as described above, and the film of the modified ionomer firmly adheres to the mixed resin of polyvinyl chloride and polyurethane.Moreover, this modified ionomer can be heat-sealed at low temperatures. Ideal as a packaging material for contents that are susceptible to seal shock.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of the printed film of the present invention. 1...Transparent film, 2...Printed image, 3...
Transparent paint, 4... Emulsion film.

Claims (1)

[Scope of claims for utility model registration] 1. After applying a printed image on the back side of a transparent film,
A transparent paint containing polyvinyl chloride, polyurethane, and a mixed resin is applied to the entire surface of the printed image, and the main component is a modified ionomer made by copolymerizing an ionomer with a styrene monomer, a (meth)acrylic acid ester monomer, or both. A transparent film that can be heat-sealed at low temperatures by applying an emulsion and drying it. 2. A transparent film heat-sealable at low temperatures as claimed in claim 1), wherein the printed image is made of a printing ink containing polyvinyl chloride and polyurethane as resin components.