Abstract:
A security seal and method for detecting tampering. The security seal includes a first member, an adhesive layer applied to the first member, and an indicia printed directly on the adhesive layer in a desired detectable pattern. In one embodiment, the first member is adhered to the second member with the indicia detectable at least through the first member. With this arrangement, the pattern becomes detectably disrupted if the first and second members are moved relative to each other. In the preferred embodiment, both of the first and second members are part of a single transparent strip that can be looped through a shipping container locking mechanism and attached to prevent unauthorized access to the shipping container. In one form, tamper indicating tape is used to form the tamper indicating message &#34;VOID&#34; thereon if tampered with, thus giving a second visual indication of tampering. Heat sensitive material is used to prevent overcoming the tamper indicating tape by heating. A method embodying the present invention includes providing a strip with adhesive thereon, printing a disruptable pattern on the adhesive, adhering the strip to a surface by use of the adhesive, and inspecting same for tampering.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to security seals, and in particular to an article and method for detecting tampering on a security seal, and a process for making the security seal. 
     Security seals are commonly used to ensure that goods or articles contained in a shipping container have not been disturbed or tampered with during transport. Historically, these security seals have been made of metal bands. However, metal seals rust or corrode, and include sharp corners and edges that can be harmful to a person using them. 
     Recently, plastic seals have become popular since they are more user friendly. Typically, plastic seals are designed with weak points so that they break in a visible location upon tampering. However, these plastic seals have not proven to be as secure or reliable as metal seals since the plastic seals tend to break accidentally, thus defeating their purpose. Further, many experts claim that plastic seals can be defeated by using heat or glue. For example, one type of plastic security seal includes a seal connector housing that can be overcome by using a thin pin to manipulate the pin and socket lock mechanism in the housing, then later reattaching the seal using glue and the like. Other methods to defeat plastic seals include heating the plastic seal in water to soften the seal and cause breakage in a hidden area. Thus when the seal is reassembled, the break is difficult to see or detect until the final destination is reached and the seal is removed, at which time the discovery of tampering is of little value. Further, plastic seals tend to be bulky to ship and store, and less than cost competitive in some applications. 
     Thus a security seal is desired to improve upon the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     The present invention is a security seal for detecting relative motion between two members. The invention includes a security seal having an adhesive means joining the two members together at a location whereat the relative motion is to be detected, the adhesive means having printed indicia applied directly thereon in a pattern prior to joining the two members together at the location, and the seal also including means for inspecting the printed indicia as applied. The indicia pattern is disrupted upon relative motion between the members after initial joinder by the adhesive, thus reflecting that the seal has been tampered with. In the preferred embodiment, the members are transparent to permit ready visual inspection of the indicia pattern from both sides. 
     In one aspect, the invention includes a security seal connectable between a shipping container with an access port and a movable door for covering the access port. The security seal includes a flexible strip including two portions, and adhesive means for joining the two portions together so that the flexible strip forms a loop. The adhesive means includes tamper indicating means for indicating relative motion between the two portions of the flexible strip after the two portions are joined. Also, the seal includes means for inspecting the tamper indicating means, the tamper indicating means being detectably disturbed upon relative motion between the two portions after initial joinder. In the preferred embodiment, the tamper indicating means includes both a tamper indicating tape which is separable upon relative movement between the two portions, and also disruptable indicia which is printed on the adhesive of the tamper indicating tape and which is disturbed upon relative movement of the two portions. Also in the preferred embodiment, a heat sensitive material is applied to one of the members, the heat sensitive material changing color if heated, thus providing evidence of an attempt to tamper with the security seal by heating the seal to a temperature at which the two members can be separated and reattached without disturbing the tamper indicating means. 
     In another aspect, the invention includes a security seal including a flexible strip, adhesive located on the strip for adhering the flexible strip to a flat surface, indicia printed on the exposed surface of the adhesive in a predetermined pattern, and the adhesive means including disruption means for disrupting the predetermined pattern if the strip is undesirably moved relative to the flat surface after attachment. Further, the security seal includes inspection means for sensing if the pattern has been disrupted. 
     In a yet narrower aspect of the invention, a narrow clear plastic strip is provided with one end being tapered to form a tongue portion and means defining an opening spaced from the other end to permit the tongue portion to be frictionally inserted in the opening to form an initial closed loop after said strip is inserted through a clasp or the like of a container to be sealed. Adhesive means are applied to the other end outwardly of the opening, the adhesive including &#34;void&#34; indicating indicia consistent with that produced and sold by 3M Company under the product no. 7380 and 7381. The adhesive includes a releasable covering which, when removed, permits the other end to be adhered to the opposite end of the strip inwardly of the tongue portion permanently securing the plastic strip in a closed loop such that if adhesive region is tampered with by relative movement of said adhered ends, a void pattern will reflect the evidence of tampering. Concurrently, additional indicia can be applied by noncontact printing to the adhesive prior to joinder of the ends, which indicia is disrupted by any relative movement between said adhered portions thereby also indicating the presence of tampering. The application of indicia directly on the adhesive eliminates any potential defeat of the security seal by application of elevated or reduced temperatures which might defeat the adhesive itself. Relative movement of the two adhered members, whether disrupting the adhesive or not, will interrupt the indicia pattern regardless of the amount of care taken in separating or reapplying same after the removal of excessive or reduced temperature gradients. 
     The present invention also is embodied in a method including providing a strip with adhesive thereon, printing a disruptable pattern on the adhesive, adhering the strip to a flat surface by use of the adhesive, and inspecting the disruptable pattern to determine if the pattern has been disrupted. 
     In another aspect, a method is provided for detecting tampering with a shipping container which is provided with an access port, a movable door associated with the access port, and a lockable mechanism associated with a door. The method includes providing a security seal having adherable portions with a disruptable pattern of indicia associated with the adherable portions, extending the security seal around the lockable mechanism, adhering the portions of the seal together to form a loop, and inspecting the disruptable pattern to determine if relative movement has occurred between the adherable portions during shipping hence indicating the lockable mechanism has been tampered with. 
     A process of the present invention includes providing a flexible strip with adhesive located thereon, the adhesive having an exposed surface, and printing a disruptable pattern on the exposed surface. In the preferred embodiment, the process includes printing on the adhesive of a tamper indicating tape, adhering a first portion of the tamper indicating tape to a flexible sheet by use of the adhesive with a second portion overhanging from said sheet, and cutting a plurality of security seals from the flexible sheet and strip thereby formed. 
     The present invention includes several advantages over known security seals. The security seal embodying the present invention is difficult to defeat or overcome, and includes two positive ways to indicate that tampering has taken place. Not only is the printed indicia itself visibly disrupted upon tampering, but a positive message appears internally in the tamper indicating tape indicating that tampering has occurred. Still further, the seal does not contain mechanical weak points intended to fracture, thus reducing or eliminating the problem of accidental breakage of the seal. Also, the seal maintains the user friendliness typical of plastic seals, such as dulled edges which do not tend to cut a person installing or removing the seal. Further, the seals of the present invention do not rust or corrode. Still further, the security seal is low cost, and readily manufacturable. Also, the security seal is planar such that it is compact to ship and store. Additionally, the seal includes a pointed end that can be threaded through a hole for temporarily holding the seal while the adhesive portion is attached, thus making the seal easy to use. 
     Other aspects, objects, and advantages of the present invention will become obvious to one of ordinary skill in the art when studied in conjunction with the description, claims and appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a security seal embodying the present invention; 
     FIG. 2 is a side view of the security seal in FIG. 1; 
     FIG. 3 is an enlarged fragmentary sectional view of the security seal in FIG. 2; 
     FIG. 4 is a perspective view of a partially installed security seal; 
     FIG. 5 is a perspective view of a fully installed security seal; 
     FIG. 6 is a perspective view of a previously installed security, seal that was removed by tampering; 
     FIG. 7 is a schematic view showing a process embodying the present invention for making security seals; 
     FIG. 8 is a plan view of the security seal illustrating the appearance of same at various steps in the process shown in FIG. 7; and 
     FIG. 9 is a schematic of a second security seal embodying the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A security seal 10 (FIGS. 1-3) embodying the present invention is provided for detecting relative motion between two members such as members or end portions 12 and 14 of flexible strip or band 16. Security seal 10 includes adhesive means in the form of a tamper indicating tape 18 attached to end portion 14, tape 18 having a backing strip 19 and an adhesive layer 20 for joining members 12 and 14 together. When members 12 and 14 are separated after being joined, tape 18 gives a detectable indication of tampering such as the &#34;VOID&#34; indication 22 and 23 (FIG. 6). To further reduce the opportunity to hide the tampering such as by covering or removing the &#34;VOID&#34; indications 22 and 23 by a white paint and reattaching members 12 and 14, seal 10 further includes a printed indicia 24 which is applied directly to adhesive 20 on tape 18. Upon separating members 12 and 14, indicia 24 is physically separated so that one part 26 of indicia 24 remains with member 12, and another part 28 of indicia 24 remains with member 14. Further, adhesive 20 is tacky, and blurs indicia 24 as members 12 and 14 are moved apart. 
     As shown, flexible strip 16 is about 3/8&#34; wide and about 9&#34; long. End portion 14 includes a hole 32, and end portion 12 includes a pointed tip 33 so that end portion 12 can be threaded into hole 32 to form a loop (FIG. 4). As end portion 12 enters hole 32, the sides of end portion 12 collapse so that end portion 12 is temporarily held therein. 
     In the preferred embodiment, flexible strip 16 is made of a clear polyester treated to accept printing and adhesive, and has a thickness of 0.007 inches. This thickness is adequate for easy handling, but also has some rigidity so that strip 16 can be manipulated in the field environment satisfactorily. Also, the material is quite strong, and offers a good surface for adhesion. Further, polyester can accept printing on a permanent basis so that instructions 30 for installation or inspection of seal 10 can be printed directly on flexible strip 16. However, it is contemplated that other materials would also work, such as polyvinylchloride (PVC) and polyethylene (PE), but with the properties of adhesion, printability, and strength somewhat negatively impacted. 
     Tamper indicating tape 18 (FIG. 2) includes two halves 34 and 36. Tape half 34 is adhered to end portion 14 with tape half 36 overhanging off the edge of end portion 14. Release paper 40 is attached to the exposed portion of adhesive 20 to prevent accidental and premature attachment of tape half 36 to an undesired surface. 
     The void indicating material or tape 18 shown is a commercially available product made by Minnesota Mining and Manufacturing Company (3M Company) under their product no. 7380 (matte) or 7381 (glossy), though it is contemplated that different tamper indicating tapes could be used which would give a permanent and conclusive indication of loss of seal integrity. The particular tape 18 noted above includes a translucent white film of material 21 located between backing strip 19 and adhesive 20. White film material 21 is adhered to backing strip 19 so that when tape 18 is first applied and then later removed, the later removal physically separates white film material 21 to form &#34;VOID&#34; indications 22, 23. Backing strip 19 is transparent and, with transparent strip 16, allows complete viewing of the tamper indicating pattern 22 and 23 (FIG. 6). 
     Indicia 24 is printed onto the exposed tacky surface of adhesive 20 (FIGS. 3, 7 and 8) before applying release paper 40. It is contemplated that a noncontact printing process will be used to print a non-drying ink thereon, however, different types of ink could be used. In particular, any ink offering visible evidence of disruption when end portions 12 and 14 are separated and adhesive 20 is disrupted can be used. Thus, this invention includes inks forming films as well as non-drying inks, although inks having a low internal strength are thought to work best since these inks tend to blur as the adhesive layer 20 is disturbed by the forced separation upon tampering. Also, the invention is contemplated to include non-visible inks or other materials which can be printed onto adhesive 20. For example, inks which emit non-visible light such as ultraviolet light, or which contain particles that can be sensed by X-ray, could also be used. 
     Printing directly on adhesive 20 is important for security seals to prevent someone from defeating seals 10. The original design intentions of the tamper indicating tape 18 was to act as label stock for conventional printing, with information being printed on the non-adhesive containing side 56 of backing strip 19 of tape 18 (FIG. 3). However where the goods are in more secluded environments, once someone has removed the tape or label from the protective band, there is an opportunity to simulate the unactivated state by simply spraying white paint or white adhesive onto indications 22 and 23 to cover-up the indicated &#34;void&#34; pattern 22 and 23 that is exposed by pulling up the tamper indicating tape 18. Thus, there would be no indication the label had been removed from its protected item, and one would have to resort to pulling the label up and noticing there is no &#34;VOID&#34; pattern to discover this tampering. This is not practical for security seals, as it would defeat the integrity of the seal. Restated, destructive testing does not make sense for seals. In the present arrangement, once tape 18 has been activated, there is no way to disguise this fact without severely damaging the markings and serialization that were placed upon the adhesive layer. This damage would provide visible evidence that the seal had been opened. 
     Also, in more secluded environments, there is a potential for heating seal 10 to overcome the seal, since most tamper indicating tapes cannot withstand high temperatures. In such case, the high temperature heating causes trouble in that many times the &#34;VOID&#34; patterns 22 and 23 will not appear upon separation of the two portions 12 and 14. For example, the 3M tape mentioned earlier may experience this problem at about 160° F. or above. 
     To further enhance the tamper indicating ability of seal 10, a heat activated, color changing material 24A (FIG. 2) is applied to tape 18 on both halves 34 and 36. It is contemplated that a number of different heat sensitive materials could be used. In the preferred embodiment, a color-former material is mixed with an activator and a catalyst to obtain a mixture that will change color at a predetermined temperature. The color-former material contemplated for use is a material called &#34;CVL-T&#34; made by Hilton Davis Chemical Company of Cincinnati, Ohio. The CVL-T material is mixed with an activator known commonly as bisphenol A (technically named 4, 4 Prime-Isopropylidenediphenol) and a catalyst commonly known as stearimide (technically named Octadecanamide). The proportions contemplated for use are one part CVL-T, 2.5 parts bisphenol A, and 1.5 parts stearimide. A small quantity of this mixture is applied to both parts 34 and 36 of the tamper evident tape 18 on the adhesive layer 20. If possible, two small &#34;VOID&#34; patterns should be printed on the tape parts 34 and 36 with this material, if manufacturing equipment will allow this. Otherwise, some other pattern can be used. Thus, when seal 10 is heated in an attempt to circumvent tampering indicating tape 18, a &#34;VOID&#34; pattern appears much like the void patterns 22 and 23 noted earlier. 
     Security seal 10 (FIGS. 4-5) is intended for use on a shipping container 42 having an access port, a movable door 44 for closing the access port, and a locking mechanism illustrated by items 46 and 48 with holes 50 and 52. To use security seal 10, seal 10 is threaded through locking mechanism holes 50 and 52 and end portion 12 is threaded partially into hole 32 to form a loop (FIG. 4). This arrangement temporarily holds seal 10 in the shape of a loop so that end portion 12 can be aligned with end portion 14. Release paper 40 is then removed, and tape half 36 is adhered to end portion 12 (FIG. 5). 
     As installed on shipping container 42, the indicia 24 and tamper evident tape 18 can be viewed from either side of the seal 10, front or back, or at an angle, and thus allows virtually 100% checking capability. Of course, any cutting or re-affixing of the band would indicate an obvious attempt at tampering, both by appearance of the &#34;VOID&#34;  indications 22 and 23, and also by the disruption of printed indicia 24, as noted above. 
     In the present loop design, there is provided good strength, thus reducing the problem of accidental breakage. The arrangement results in a shear load on the adhesive tape when the loop is pulled, as opposed to weaker type plastic loops that utilize tensile, cleavage or peel loads. For example, many plastic seals break with a static load of about 25 pounds, while the present seals were tested to have a strength in the area of 55 pounds. 
     Additionally, the construction of seal 10 allows easier use since the loop formed by seal 10 is self-supporting before tape half 36 is applied. This eliminates a problem of a &#34;moving target&#34; when a person installing seal 10 is trying to apply tape half 36 to the seal end portion 16. Further, testing indicates that this material as provided by 3M Company can withstand a wide range of environmental conditions and still provides its indication pattern, and its retention strength. 
     Seals 10 are thin and planar, weighing about 75% less than conventional plastic seals and taking up about 95% space, thus making the seals less expensive and easier to ship and store. Also, as described below, seals 10 can be arranged in a sheet of 25 or 50 so that they can be easily carried such as in a shipping foreman&#39;s back pocket, for attachment to containers on a dock. Further, by keeping the seals interconnected, the serial numbers can be kept in numerical sequence. 
     Concerning the process of manufacturing seals 10 (FIGS. 7 and 8), rolls 66 of the tamper indicating tape 18 are unrolled and printed on by noncontact printing press 58 to print serial numbers and other indicia 24 onto the exposed adhesive surface of adhesive 20. Also, high temperature indicating mixture 24A is printed or sprayed onto adhesive 20 in a pattern as desired, such as a &#34;VOID&#34; pattern. After printing, a portion of release material 40 is applied to adhesive tape 20 on portion 36 (FIG. 8). The exposed portion 34 of tape 18 is then attached to sheet 60 in a substantially continuous process. Sheets 60 are then punched by dies to form holes 32 and slit by slitters to form the pointed shape 33 of end portion 16 at station 68. The slitters also score flexible sheet 60 along score lines 62 to form multiple adjacent seals 10 in sheet 60. Seals 10 are removably held together in sheets 60 after slitting by breakable tabs 64 such that they are easily removed when it is desired to use same. The final product is shipped in boxes with about 25 seals per sheet. Notably, instructions 30 can be printed onto sheets 60 or strip 16 at any time. 
     A seal 90 (FIG. 9) can also be made for application onto an envelope 92 or other similar security bag with exposed flat surfaces 94 and 96. Seal 90 is substantially a tamper indicating tape 98 such as was described above for tape 18. Indicia 100 is printed directly onto the adhesive of tape 98 before application of tape 90 to flat surfaces 94 and 96. If seal 90 is removed, indications appear similar to the &#34;VOID&#34; indication 22 and 23 noted above. Also, the printed indicia 100 is blurred and physically separated, as also noted above. Notably, seal 90 could be pre-applied to envelope 92, or applied on-site. 
     Thus, a security seal is provided for detecting relative motion between two members. The seal includes an adhesive means joining the two members together at a location whereat the relative motion is to be detected, the adhesive means having printed indicia applied directly thereon in a pattern prior to joining the two members together at the location, and access means for inspecting the printed indicia as applied. The indicia pattern is disrupted upon relative motion between the members after initial joinder by the adhesive, thus reflecting that the seal has been tampered with. 
     Though the preferred embodiment has been described in detail herein, the invention is not intended to be limited to the preferred embodiment described, but is intended to be interpreted broadly as claimed and as interpreted under the Doctrine of Equivalents.