HK1032372A - Tear-off strip with protective feature, a method of producing it and also its use in packaging material - Google Patents

Description

Pull-open tab with security feature, method for its manufacture and use in packaging material

The present invention relates to a pull-off strip and the use of a pull-off strip with a security feature on consumer goods, food packages and the like.

The production and sale of counterfeit articles is an ever-increasing problem. Such counterfeit products are often packaged in a false or fake manner similar to the genuine product, thereby deceiving the prospective consumer into believing that the product they buy is genuine. This creates various problems. On the one hand, the business of the manufacturer of the genuine article is affected. On the other hand, the intellectual property rights of the owner of the rights to the product are fraudulently picked. More importantly, in many cases, counterfeit products are of poor quality and can cause an unthinkable loss of the manufacturer's image. Poor quality also increases complaints about product reliability, so that the manufacturer of genuine products is forced to prove that the product causing the loss does not come from him. Thus, there is a need to mark the genuine product so that the consumer can identify the genuine product and, upon complaints, can prove that the product is genuine.

Packages made of plastic film, paper, cardboard or composites of these materials are usually provided with a pull-off strip. The tape is secured to the package and a self-adhesive or heat-adhesive composition is applied to the tape. Such pull-off tapes are described in US4,887,714 and US4,844,962.

EP0585076 describes the introduction of security features into packages in the form of adhesive strips. In this case, the holographic element serves as a security feature. One disadvantage of holograms is that their extraordinary effect is often lost in low light. Moreover, the manufacture of holograms is a complicated and costly production process. In particular when manufacturing pull-off tapes, the production process must be inserted upstream and cannot be integrated in the current production steps. The film supported for this purpose must be prepared and coated with embossing lacquer. The holographic pattern is then embossed. It must be metallized in the next production step. Then it can enter the traditional production process of the pull-off strip. Thus, the production process becomes more expensive and complicated due to the multiple steps.

The object of the invention is to provide a pull-off strip with a safety feature, wherein the introduction of the safety feature does not involve new additional production steps in the production of the pull-off strip.

The invention therefore provides a pull-off strip with a security feature comprising a support film to one side of which a sealing layer is applied, optionally a release layer may be applied to the other side of the support film, characterised in that a special security ink is printed on one side of the support film.

The support film is preferably a cellulose film, poly (vinyl chloride), vinyl chloride copolymer, vinyl chloride terpolymer, polyester, polypropylene copolymer, polypropylene terpolymer, polypropylene-polyethylene copolymer, polyamide, polystyrene copolymer, polystyrene terpolymer, polycarbonate, polyketone, polymethacrylate or polymethacrylate copolymer; in particular, uniaxially oriented polypropylene or polypropylene-polyethylene copolymer is preferred.

In a particular embodiment, the support film may be a laminate with one or more of a polymer film, with paper, with a metallized polymer film, with a metal foil, or a vacuum deposited film.

The sealing layer is preferably a layer made of a self-adhesive contact material based on polyacrylic acid or natural fat or synthetic resin. The optional release layer is preferably a UV-crosslinkable silicon coating.

The invention also provides a method for producing a pull-off strip having a security feature in which a support film is printed with security ink, a sealing layer is applied thereto, and a release layer is optionally applied to the other side of the support film.

According to the invention, the printed pull-off strip is produced in such a way that in a single operation a support film is printed and a sealing medium, such as a hot-melt contact adhesive, is added to the printing ink. A release layer may also optionally be applied to the other side of the support film to prevent clogging. By using a suitable printing ink, a security feature can be introduced into the pull-off strip during this production process.

If the printing is carried out by means of reverse printing, the printed security ink can be read through the packaging film, the adhesive, and finally the support film on the finished package.

The support film may have a thickness of between 10 and 100 micrometers and a width of between 1 and 100 millimeters. The thickness is preferably 10 to 40 μm, and the width is preferably 1.5 to 10 mm, more preferably 1 to 5 mm.

The sealing layer may comprise a sealing medium such as polyethylene or a so-called hot melt coating, the thickness of the layer being between 1 and 20 microns, the sealing temperature being conventionally above 100 ℃.

Preferably, a cold-bondable self-adhesive based on polyacrylic acid or, in particular, based on natural or synthetic resins is used as sealing medium.

In the case of self-adhesive contact materials, the reverse side of the film is provided with a release coating. The coating preferably comprises a silicon layer, more preferably a UV-crosslinkable silicon coating.

The support film may be printed in a single color, or in multiple colors. Any printing method that can be used for the film can be used for this purpose. The printing may be by conventional packaging printing methods such as offset, screen, flexo, UV flexo or gravure; in particular by flexographic or gravure printing, more particularly by gravure printing.

The security inks used must have particular characteristics suitable for ensuring the authenticity of the articles to be packaged.

The security ink employed may be the ink having the most variable effect. For example, thermochromic inks are suitable, which change color reversibly or irreversibly at a certain temperature; daylight fluorescent inks, the brightness of which depends on the UV light component of the light, allowing the authenticity to be checked with the technical methods of colour copiers widely used today; luminescent inks which absorb UV light and emit visible light of longer wavelength, with the result that illumination with UV lamps can achieve special color effects, emission being fast after absorption of light with "fluorescence" or "phosphorescence" for a long time; the infrared ink shows absorption characteristics under infrared light, and is different from an ink area with the same effect in sunlight; photochromic inks reversibly change hue when exposed to UV light; the hue of the metamorphic ink depends on the viewing angle.

The pull-off strip according to the invention can in an advantageous manner prevent the product from being counterfeited. The purpose of the security element is to be able to provide proof of authenticity in the event of counterfeiting, or to enable a consumer, an intermediary, or a regulatory authority, such as customs or police, to identify the authenticity of a product in a simple manner.

The pull-off strip of the described construction can be produced on conventional machines. The release layer is provided with successively dried or cured layers using a multi-roll application unit.

Printing on one side of the support film can be carried out using known printing machines, and depending on the number of effects required, one or more printing units can be filled with security ink, which, like conventional inks, can be combined to form a printed image. The sealing medium is applied to the print in gravure printing, either on-line or off-line, or by slot die or other suitable method.

According to the invention, the pull-off strip with the security element can be provided in a particularly simple and economical manner, since the security element is introduced by means of a printing method without additional production steps.

The invention also relates to a packaging material comprising a pull-off strip according to the invention, such as a film for packaging cigarettes, CD discs or foodstuffs.

The invention is further described, but not limited, by the following examples in which all ingredients and percentages are by weight unless otherwise indicated.

Example 1

A uniaxially oriented polypropylene film having a thickness of 38 μm, wherein the maximum tensile force is more than 160 newton, the elongation at break is more than 25%, the tensile force at 10% elongation is 32 newton, the tear propagation force is more than 6 newton, the tensile force rebound in the longitudinal direction is more than 1250 kilojoules per square meter, the tensile force rebound in the transverse direction is more than 100 kilojoules per square meter, the shrinkage (at 125 ℃ and 10 minutes) is less than 6%, and the amount of pre-treatment (corona treatment) is more than 38 millinewtons per meter, which film is coated with a mixture of silicon comprising solvent-free silicone acrylates with a polymerised photo-initiator, which is free-radically cross-linked by UV radiation in a protective gas environment, the mixing ratio being determined by the separating action of the cured silicone acrylate layers.

The next step involves printing the opposite side of the silicon-coated side by gravure printing, where the surface tension is adjusted beforehand to more than 38 millinewtons per square meter by corona treatment. One commercially available hot melt pressure sensitive adhesive is based on an SBS copolymer and a condensation resin, which is added to a printing ink (which is based on a polyvinyl butyral binder). The application amount was 10 g/m. In the next step, the film with this finish was cut to a width of 2 mm and a length of 6000 meters was wound onto a reel.

Example 2

A cellulose film having a thickness of 30 microns printed by gravure printing (using the ink of example 1) and having a hot melt adhesive added to the ink, the adhesive comprising 25 to 45% ethylene vinyl acetate copolymer, 20 to 35% cycloethanone resin, 15 to 25% saturated hydrocarbon resin, 5 to 10% methyl styrene hydrocarbon resin, and less than 10% oligomeric polyurethane. The application amount was 4 g/m. In the next step, the film with this finish was cut to a width of 2 mm and a length of 6000 meters was wound onto a reel.

Example 3

The same procedure was used as in example 1. However, with the commercially available acrylate emulsion as contact adhesive, the solids content is approximately 53% and the flow time in the DIN4 disruptor is 60 seconds. The application amount is 3 g/square meter; the emulsion in water is applied in gravure printing.

Although the foregoing invention has been described in some detail for purposes of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims (11)

1. A pull-off strip comprising (i) a support film and (ii) a sealing layer bonded to a surface of said support film, and optionally (iii) a release layer bonded to the other surface of said support film, said support film comprising a pattern printed with a particular security ink.

2. A pull-off tape as claimed in claim 1 wherein the support film comprises a material selected from the group consisting of cellulose, (co) poly (vinyl chloride), polyester, (co) polypropylene, amide, (co) polyethylene, (co) polystyrene, polycarbonate, polyketone and (co) poly (meth) acrylate.

3. A pull-off tape according to claim 1 wherein the support film is uniaxially or biaxially oriented.

4. A pull-off tape according to claim 1 wherein the support film is a laminate comprising at least one member selected from the group consisting of polymeric film, paper and metal foil.

5. A pull-apart tape according to claim 4 wherein the polymeric film is metallized.

6. A pull-apart strip according to claim 1 wherein the sealing layer is a self-adhesive.

7. A pull strip as claimed in claim 1 wherein the sealing layer comprises a UV cross-linkable silicon coating.

8. A method of producing a pull-off strip comprising printing a pattern on one surface of a supporting film, adhesively applying a sealing layer to said surface, and optionally applying a release layer to the other surface of said supporting film.

9. The method of claim 8, wherein the printing is gravure printing.

10. The method of claim 8, wherein the printing is flexographic printing.

11. A packaging material comprising the pull-open tab of claim 1.