Europaisches Patentamt (19) European Patent Office Office europeenpeen des brevets EP 0 530 267 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) intci.6: G09F 3/02, B65D 33/34, of the grant of the patent: B65D 27/30 16.10.1996 Bulletin 1996/42 (86) International application number: (21) Application number: 91909909.3 PCT/GB91/00809 Date of 22.05.1991 (22) filing: (87) International publication number: WO 91/18377 (28.11.1991 Gazette 1991/27) (54) TAMPER RESISTING SECURITY SEAL ORIGINALITATSSICHERHEITSSIEGEL CACHET DE SECURITE ANTI-SPOLIATION (84) Designated Contracting States: (74) Representative: AT BE CH DE DK ES FR GR IT LI LU NL SE Skone James, Robert Edmund et al GILL JENNINGS & EVERY (30) Priority: 22.05.1990 GB 9011457 Broadgate House 7 Eldon Street (43) Date of publication of application: London EC2M 7LH (GB) 10.03.1993 Bulletin 1993/10 (56) References cited: (73) Proprietor: DE LA RUE HOLOGRAPHICS LIMITED WO-A-89/08586 FR-A- 1 151 039 London WC2N 4DE (GB) FR-A- 2 445 568 GB-A-2 211 760 US-A- 4 834 552 (72) Inventors: • KAY, Ralph 15 Juniper Drive Ray Park Road • Patent Abstracts of Japan, volume 12, no. 354, Berkshire SL6 8RE (GB) (P-761)[3201] 22 September 1988; & JP A 63 • JONES, Keith, Alan 106780 (TOPPAN PRINTING CO.) 11 May 1988 Berkshire TW19 5EW (GB) • SILK, Adam, Justin 88 Brookhouse Road Cove Hants G414 0BT (GB) DO Is- CO CM CO lO Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice the Patent Office of the Notice of shall be filed in o to European opposition to European patent granted. opposition a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. a. 99(1) European Patent Convention). LU Printed by Jouve, 75001 PARIS (FR) 1 EP 0 530 267 B1 2 Description the holographic impression is supplemented by a partial appearance of the underlying surface which may be a The invention relates to a tamper resistant security photograph. seal, for example for sealing containers such as security Makowka (US-A-4834552) describes making pouches and the like which are used for conveying items s tamper-evident seals for plastic envelopes. The seal is of value such as banknotes, letters of credit and the like. double sided requiring two adhesives and is concealed It is extremely important that any such pouches pos- undertheflap in use. Inspection of tamper evidence can sess tamperproof or tamper-evident seals. Various at- only be by folding back the flap and looking at the edges. tempts have been made in the past to make such seals. Paper or cloth having a porous structure is used to pro- Generally these seals are adhesive backed tape 10 tect against low temperature attack. constructions which are applied under or over the edge The use of holographic effects for security purposes of the pouch flap so that the flap is held in place against is thus well known. The fineness of optical embossing the body of the pouch in a firm and tamperproof manner. and the nature of the holographic image make it very They can also be in the form of labels. difficult to alter such devices or manufacture them In recent years the use of metallised films has been 15 afresh. replaced by the use of optically embossed metallised The term "counterfeiting" may be taken to mean the films, which have a holographic or diffractive image. copying of an article by fresh but fraudulent manufac- Such a construction was recently described by Ad- ture. vanced Holographies in GB-A-2211760. The advantage Holographic devices are counterfeit resistant and of using holographic films is that their counterfeiting is 20 may be counterfeit indicating. It is relatively difficult to extremely difficult. The construction of the general pur- construct an holographic image by "copying" it on a ho- pose tape is similar to tapes used for hot stamping, for lographic table even if one were available. Slight varia- example as described in GB-A-21 29739. tions in image quality would also be readily detected in Very generally these tapes consist of a supporting any copy because of the fineness of the surface relief film, a wax release layer, and a coating of an embossa- 25 structures employed. The counterfeiter would need to ble thermoplastic polymer which has been subsequently have access to holographic equipment, embossing diffractively embossed. Vapour deposited aluminium is equipment and metallising equipment to manufacture then applied with an optional protective layer. The ad- copies, in practice this would be very difficult. hesive is then applied from a coating solution. WO-A- Holographic seals are also forgery resistant by 88/05728 introduces the general concept of a holo- 30 which is meant alteration resistant. They are also readily graphic protective film having a wax interlayer. Then a alteration indicating, as it is very difficult for a forger to general purpose pressure sensitive adhesive layer is replace accurately any cut away or altered area: the applied which is in turn protected by a peelable release fineness of optical relief embossing acts as a consider- paper. In use, the tape is fixed to a substrate using the able deterrent. adhesive. It is difficult to copy or alter. 35 Despite many holographic seal variants disclosed JP-A-631 06780 also describes another general in the art, these all being directed towards enhancing in purpose holographic tape. The tape is designed with various ways the anti-counterfeiting properties and/or weaker bonding between a protective layer over the ho- anti-forgery properties, the importance of providing sub- lographic layer and an adhesive layer than between a stitution resistance, which is the third form of attack transparent film on which the tape is formed and the ho- 40 which a criminal may make, has not hitherto been max- lographic layer. imised. Similar constructions are known for covering large The prior art recognises that holographic seals areas of, say, carton card in which an holographic trans- should not be readily detachable from the substrate to fer foil is rolled onto the card to produce a card having which the seals are attached. Thus for example it is rec- a diffractive metallic appearance. Such transfer foils are 45 ognised in GB-B-21 36352 that the holographic layer not known to have been used for security pouch seals. should be weak so that attempted removal of the carrier However, they are of similar structure to the tapes men- will destroy the holographic embossing. tioned above except that instead of a wax release layer Similarly in GB-A-2211760 the removal of the car- the embossable layer is chosen to have release prop- rier film (aided by the strength of the wax it is assumed) erties from the carrier film. so will cause damage to the holographic layers. Searle (GB-B-21 36352) discloses holographic While such structures have been used previously, seals in which locally embossed areas of thermoplastic they are unlikely to have provided substitution preven- polymer are covered by a metallised film which is then tion ortamper prevention and possibly tamper indicating demetallised. This leaves areas which are unprotected properties for example when such substitution or tam- by the holographic image which is undesirable in case 55 pering is undertaken at extremes of ambient tempera- forgery is attempted. ture during freezing or heating. Neither is there any in- Dai Nippon Insatsu in US-A-4856857 discloses dication in the prior art as to how a superior holographic transparent embossed holographic structures in which tape possessing such properties may be made. 2 3 EP 0 530 267 B1 4 By substitution is meant the detachment of all or scale using conventional production equipment. part of the seal allowing its replacement without giving These new security seals, which are resistant to a evidence of that having happened. For example if a seal wide range of criminal challenges, may be made with a on a security pouch could be temporarily detached and structure which is so fragile that it will very readily fail. then resealed without trace, this would be particularly 5 We have realised that it is important to make an im- undesirable. Yet many of the prior art seals are suscep- proved seal which has high resistance to counterfeiting, tible to such action. forgery and substitution, yet which will degrade irrevers- By tampering is meant unauthorised interference ibly and readily under many conditions to which the crim- with the seal whether for the purposes of counterfeiting, inal may subject it. forgery or substitution. 10 We have devised a new type of tamper resistant se- In this specification, by printing is meant the appli- curity seal which is capable of resisting not only a high cation of readable markings of dyes and/or pigments temperature challenge but also a challenge at low tem- such as those delivered during printing operations, es- perature. Such a challenge could result in complete de- pecially thin ink film printing operations such as occur in struction of the optical pattern defining layer, a variation lithographic, flexographic and gravure printing. The is in that optical pattern, or a variation in the laminate struc- marking may be employed under electronic control such ture such that any attempt to remove the seal from a as during laser printing of toners, ink jet printing, thermal substrate will cause the optical pattern to be varied or transfer printing, impact ribbon printing and the like. destroyed.