WO2009122423A2

WO2009122423A2 - An improved security tamper-evident tape and the process of manufacturing the same

Info

Publication number: WO2009122423A2
Application number: PCT/IN2008/000432
Authority: WO
Inventors: Pradip Hiralal Shroff; Ashok Biswas; Somnath Bhattacharya
Original assignee: Prs Solutions Private Limited
Priority date: 2008-04-03
Filing date: 2008-07-07
Publication date: 2009-10-08
Also published as: WO2009122423A3; WO2009122423A4

Abstract

A multilayer adhesive tape having a backing based on transparent or translucent polymeric film, a release layer and a coloured pressure sensitive adhesive layer on one surface which indicates the tampering of a package by the fact that when the tape is peeled away the adhesive layer splits in predetermined manner and displays a message which was otherwise not visible on both the surface as well as on the removed film, and once destructed the message remains visible even if the removed tape is reapplied exactly at the original position. The said tape is manufactured in two simple steps and in one of the steps a coloured adhesive is used thereby eliminating the use of primer layer and/ or ink printing. Adhesive layer is protected by a release coated liner which makes the tape suitable for use as a closure for Security Tamper-Evident Bag (STEB).

Description

FIELD OF INVENTION

The present invention relates to a "An improved security tamper- evident tape and the process of manufacturing the same". It is a multi layer adhesive tape having a transparent or translucent polymeric film, a release layer and a coloured pressure sensitive adhesive layer on one surface of the polymeric film. The adhesive tape indicates the tampering of a package by the fact that when the tape is peeled away the adhesive layer splits in predetermined manner and displays a message which was otherwise not visible both on the substrate as well as on the removed film. Once destructed the message remains visible even if the removed tape is reapplied exactly at the original position. The tape is specially suitable for sealing clear, transparent Security Tamper-Evident Bag (STEB) made of polyethylene / polypropylene films which are used by duty free shops in all airports to comply with new rules for carrying Liquids, Gels and Aerosols (commonly termed as LAGs) in the cabin by any passenger. The said tape can also be used as 'tamper evident seal' to prevent the fraudsters and counterfeiters from illegal, unauthorized and unintended use of any packed article.

DESCRIPTION OF THE PRIOR ART

The new security regulations for carry-on luggage, which have been in effect since November 2006, place additional restrictions on air travelers. Security control guidelines for screening liquids, gels and aerosols as recommended by ICAO in December 2006 permits Liquids, gels and aerosols (LAGs), in any volume, purchased at airport retail outlets or on board aircraft during the day(s) of the journey provided they are carried in a Security Tamper- Evident Bag (STEBs). Same guidelines also defined the technical specifications for STEBs, and as per the specification such STEBs are to be made by using transparent (high impact low density polyethylene (LDPE) or equivalent material in thickness of minimum 50 microns; on the top face of the STEB the closure should have red tamper evident tape of minimum 30 mm width with 40 mm release liner; the tape should have high tack pressure sensitive self adhesive and integral security devices/ hidden graphics to show if tampered with.

The most common type of tape which meets the requirements of STEBs are VOID tape or evidence tape. When the tape is peeled away it leaves behind an adhesive residue that displays a VOID or any other message.

US 6537634 describes one similar tape which is based on oriented thermoplastic film where upper face is coated with a silicone release coating and whose lower face has many layers applied to it such as (a) a primer layer which is applied on pre-determined way and anchors very well to the thermoplastic film; (b) a ink layer which anchors well to the primer layer but does not anchor to the polymeric film and (c) a pressure sensitive adhesive layer which has a better anchorage to the ink layer than the ink has on the film. Such tape is supplied in the form of self wound rolls and do not have any release liner and thus is not suitable for STEBs. U.S. Pat. No. 5,060,848 describes a tamper evident seal that uses a layer of nitrocellulose or acrylic ink that breaks apart in a selected pattern when the seal is forced open. The layer of ink is adhered to a polyester film that is part of the seal. Before applying the ink, the plastic film is masked with a desired pattern of a silicon oil material, which normally causes the ink to break apart in the masked pattern when the seal is forced open. Also, to ensure that the ink layer adheres to the silicon oil layer and polyester film, a primer is applied over the silicon oil layer, and the ink is then applied over the primer. This process is expensive as several layers and correspondingly several steps in manufacturing are involved. Furthermore, this process is not environment friendly as use of nitrocellulose or acrylic ink, silicone oil and primer involves use of solvents.

To overcome these shortcomings, what is needed is a tape with a release liner part of which can be removed by STEB manufacturers and tape applied on one end of the closer flap at the time of bag manufacturing and remaining liner can be peeled off and tape applied to close the bag after filling the contents, provides evidence of tampering or any attempt to tamper the seal , and the evidence of tampering provided should be clearly seen. Furthermore, the tape providing these features should also be relatively inexpensive, can be produced by simple conventional coating techniques and include only materials which releases minimum amount of volatile organic compounds (VOC). As explained in the following, the present invention provides a tape that meets these requirements. SUMMARY OF THE INVENTION

The present invention relates to an improved security tamper- evident tape. The invention accordingly provides a multilayer adhesive tape having a backing which is transparent or translucent polymeric film which exhibits strong adhesion with conventional printing inks and/ or pressure sensitive adhesives. On the lower face of the said polymeric film a transparent release layer is applied which covers only part of the surface and does not anchors well to the said polymeric film. On drying the said release layer leaves portions of the said polymeric film in an indicia-defining pattern. A pressure sensitive adhesive, which has been formulated to give the required colour, for example red, is applied on the release coated side of the said polymeric film over the full area of the applied release layer and the free polymeric film surface so that the said release layer anchors better to the said pressure sensitive adhesive layer than to the said polymeric film which itself anchors to the pressure sensitive adhesive layer better than the anchorage of the said release layer to the said polymeric film. A protective layer of release liner is then applied over the pressure sensitive adhesive layer so that the force required to separate the said adhesive layer and the said release liner is less than the force required to separate the said adhesive layer and the said release layer and/ or the said polymeric film itself. The tamper-evident adhesive tape so formed is slit to the desired width and length by conventional slitting methods.

It is evident from the process disclosed above that the said tape is manufactured by a process which can be carried out by conventional coating techniques and does not involve the steps of primer deposition on silicone release coating and/or deposition of ink layer over the said primer layer.

Optionally, when additional security features are desired, the slit rolls can be printed with message, logo, bar code and/ or serial numbers on the top surface by using conventional flexographic and/or non contact printing techniques known in the industry using water based, solvent based or U V curable inks. Such printing is possible on individual rolls by which customer specific designs can be created economically even for a minimum of one roll.

When the adhesive tape of the invention is removed from the surface on which it has been applied, the hidden message transfers to the transparent or translucent polymeric film due to the fact that the said adhesive has stronger adhesion to the polymeric film than to the surface on which it was applied. The portion of the adhesive covering the release layer along with the said release layer remains on the surface on which the tape was applied as the adhesion of the adhesive to the applied surface is stronger than the adhesion of the adhesive and the release layer to the polymeric film. An appropriate gradation of the release forces of the multiplayer construction produces reliable separation within the adhesive tape and on removal the message which was not readable on the tape becomes readable both on the film and the surface and the said message remains readable even when the tape is replaced exactly on the same site, thereby, giving clear indication of tampering and or attempt of tampering. The polymeric film used in this invention is a 25 to 100 micron thick transparent or translucent polyester film, however, other transparent or translucent films such as poly vinyl chloride, polystyrene, corona treated polyethylene or polypropylene of similar thickness can also be used.

The transparent release layer is deposited by flexographic printing techniques or by gravior coating technique to achieve a desirable thickness of 0.5 to 2.0 g/m² and using a 2% to 20% solution of poly vinyl alcohol in water/ alcohol mixture or cellulose acetate butyrate in Toluene/ Xylene/ methyl ethyl ketone, ethyl acetate or mixture thereof. The raised portions of the flexographic plate or engraved portions of the gravier roller transfer the release solution on the portions other than the message portion.

The adhesive is applied by process using conventional method of coating equipment followed by using known drying-methods. The adhesive used can be solvent based acrylic adhesive or water based acrylic emulsion in which colourants and/ or pigments can be dispersed uniformly. The adhesive is manufactured by blending commercially available solvent based acrylic adhesive or water based acrylic emulsions and colourants and /or pigments in a proportion so as to give colour and intensity of colour as required in a high shear stirrer. The colourants used can be an universal stainer, a liquid dye, a blend of iron oxide with dioctyl butyl phathalate, inorganic / organic pigments dispersed / dissolved in solvents etc. The release liner in the present invention is a silicone release resin coated substrate which could be either different papers like Glassine, bleached Kraft, polycoated or various polymeric films like Polyester, Polyethylene, Polyvinyl Chloride etc.

The stock formed by aforesaid technique and ingredients is utilized as the basic raw material which goes into the making the tape. For achieving this, wider width stock is slit in the required width and in endless roll form.

Optionally, to make the tape customer specific and to raise still higher level of security, in one of the embodiments, the other surface of the polyester film can be printed generic printing of customer name, logo, messages etc. and/or specific printing of logos, bar codes and/or serial numbers by conventional printing methods such as flexographic, gravier, roll to roll screen, non contact ink jet printers and /or thermal transfer printing.

The following is the schematic representation of the construction of the an improved security tamper - evident tape

PPPPPPPPPPPPPPP printing, barcoad/ serial number (optional)

_{FFFFFFFFFFFFFFF} Transparent / translucent polymeric film

RR RR RR RR Release coating (partial deposition)

AAAAAAAAAAAAA Coloured acrylic adhesive

LLLLLLLLLLLLLLLL Silicone resin coated substrate

Tape before removal

Transparent polymeric film

Release layer

Coloured adhesive layer

Polyethylene bag

Tape after removal

Claims

WE CLAIM:

1. An improved security tamper - evident tape comprising of a transparent or translucent polymeric film, a transparent or translucent release layer partially covering the lower surface of the polymeric film so as to give a reverse image of the hidden message, a formulated coloured pressure sensitive adhesive layer covering both release layer and polymeric film, and a release coated liner; and the said tape is manufactured by

(a) coating a transparent release layer on one surface of the transparent /translucent polymeric film in such a way that it covers the entire area of the film except the area where some message is appearing giving reverse image of the message;

(b) coating of the said formulated colour adhesive on the release layer printed side covering the entire surface which includes the release layer coating as deposited in step (a) above and the portion where release layer was not deposited in step (a) above and where polymeric film is visible;

(c) lamination of siliconised release liner on the adhesive coated side;

(d) slitting of the said adhesive tape obtained in step (c) in desired length and size; (e) printing on the other side of the polymeric film, which is optional.

2. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the polymeric film is having 25 to 75 micron thickness.

3. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the formulated colour adhesive is a combination of water based/ solvent based acrylic adhesive in which cross linking hardener and/or colourants and/or pigments can be dispersed uniformly.

4. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claims 1 and 3 above wherein the colourants used can be an universal stainer, a liquid dye, a blend of iron oxide with dioctyl butyl phathalate, inorganic / organic pigments dispersed / dissolved in solvents.

5. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claims 1 and 2 above wherein the said polymeric film is transparent or translucent polyester film.

6. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the release layer has stronger anchorage to the pressure sensitive layer than the polymeric film on which it is applied.

7. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the pressure sensitive adhesive has a stronger adhesion with polymeric film than the release layer and /or polyethylene bags.

8. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the adhesive layer splits on removal of the tape from the surface on which applied in such a manner that the adhesive on release layer portion of the tape remains on the surface and adhesive on non- release coated portion transfers to the polymeric film thereby exhibiting the hidden message both on the surface and on the removed film.

9. "An improved security tamper-evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the release layer is deposited by flexographic printing techniques or by gravier coating technique to achieve a desirable thickness of 0.5 to 2.0 g/m² and using a 2% to 20% solution of poly vinyl alcohol in water/ alcohol mixture or cellulose acetate butyrate in Toluene/ Xylene /methyl ethyl ketone, ethyl acetate or mixture thereof.

10. "An improved security tamper - evident tape and the process of manufacturing the same" as claimed in Claim 1 above wherein the release liner is one side silicone release coated paper such as bleached kraft, glassine, polycoated kraft or film such as polyester film, polyethylene film, polypropylene film or poly vinyl chloride film.

11. "An improved security tamper - evident tape and the process of manufacturing the same" as claimed in Claims 1 to 10 above by which an improved security tamper-evident tape is obtained.