Holographic images in the form of a metal laminated between two film layers are frequently used as security devices in many products including, e. g., credit cards, tickets, bus passes and other repeatedly used tokens having monetary value.

Box sealing tape is used to secure flaps or covers of a box so that the box will not accidentally open during normal shipment, handling, and storage.

Box sealing tape assists in maintaining the integrity of a box throughout the entire distribution cycle. Automatic tape dispensers such as case sealers, e. g., automatic case sealers commercially available under the trade designation 3M-Matic from Minnesota Mining and Manufacturing Company ("3M"), are frequently used in high volume packaging operations to rapidly unwind and apply box sealing tape to a variety of packaging materials. Some automatic case sealers operate at speeds of about 85 ft/min (28. 3 m/min), while others operate at speeds of up to 150 ft/min (45. 7 m/min). The force exerted on a roll of tape to unwind the roll during a box sealing process is frequently applied and then quickly removed as the unwinding process is repeatedly stopped and started. If the unwind force of the roll of tape is not sufficiently high, over spinning (also referred to as over travel), in which the roll of the tape continues to unwind after the force exerted on the roll of tape to effect unwind has been removed, can occur. Thus, box sealing tape is often formulated to exhibit a high unwind force, in part, to prevent the occurrence of overspinning during high speed automatic tape dispensing operations. Box sealing tape that is made with block copolymer based pressure-sensitive adhesive compositions and exhibits a high unwind force, tends to exhibit a shocky unwind.

Summarv of the Invention In one aspect, the invention features an adhesive tape that includes : a) a backing that includes a holographic image, where the backing has a first major surface and a second major surface ; and b) a pressure-sensitive adhesive composition provided on the first major surface of the backing. The pressure- sensitive adhesive composition and the backing are selected such that the unwind force of the tape is at least about 1. 1 N/dm at unwind speeds of about 0. 3 m/min, and the tape exhibits a smooth release upon unwind. In one embodiment, the unwind force of the tape is at least about 1. 1 N/dm at unwind speeds of no greater than about 30 m/min. In another embodiment, the unwind force of the tape is at least about 2. 2 N/dm at unwind speeds of no greater than about 30 m/min. In other embodiments, the unwind force of the tape is at least about 4. 4 N/dm at unwind speeds of no greater than about 30 m/min.

In some embodiments, the adhesive tape exhibits a shockiness index of no greater than about 3, preferably no greater than about 2, more preferably no greater than about 1.

In one embodiment, the adhesive composition includes styrene- isoprene-styrene block copolymer and exhibits a 180° peel adhesion of at least about 20 N/dm to stainless steel.

In other embodiments, the adhesive tape further includes a low surface energy composition provided on the second major surface of the backing. The low surface energy composition includes a compound selected from the group consisting of silicone polyurethanes, silicone polyureas, silicone polyurethane/ureas, epoxy functional silicones, epoxy styrenated silicones, acrylate functional silicones, silicone grafted copolymers, condensation cured organopolysiloxanes, addition cured organopolysiloxanes, fluorocarbon copolymers, 16-20 carbon alkyl side chain copolymers, and combinations thereof.

In another aspect, the invention features an article that includes the above-described adhesive tape, and a dispenser capable of dispensing the tape.

In other aspects, the invention features a method of using the above- described adhesive tape. The method includes unwinding a roll of the tape at unwind speeds of at least about 30 m/min.

The invention provides an adhesive tape that, when in the form of a roll, exhibits smooth unwind (i. e., a relatively low shockiness index), yet has an unwind force that is sufficient to prevent overspinning. The adhesive tape can be formulated to exhibit these properties (i. e., relatively high unwind force and smooth unwind) at low unwind speeds, at unwind speeds of up to 30 m/min, and preferably at unwind speeds of up to 50 m/min.

The invention also provides a holographic imaged backed adhesive tape that, upon unwind, is free from damage (i. e., visually perceptible creasing, distortion and combinations thereof) of the holographic image present on the backing.

The adhesive tape of the present invention is particularly useful in box sealing applications and is capable of maintaining the above-described properties while being dispensed from a high speed automatic tape dispenser such as an automatic case sealer. The tape can also perform a decorative function.

Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof, and from the claims.

Descnpnon of the Preferred Embodiments The adhesive tape features a pressure-sensitive adhesive composition provided on a first major surface of a backing that includes a holographic image.

The adhesive tape can also include a low surface energy composition provided on a second major surface of the backing. The adhesive composition and the optional low surface energy composition are selected to provide a roll of tape that : A) exhibits an unwind force that is sufficiently high to prevent overspinning of the roll of tape when the force exerted on the roll of tape to effect unwind is removed, e. g., an unwind force of at least about 1. 1 N/dm (1 oz/in), more preferably at least about 2. 2 N/dm (2 oz/in), most preferably at least about 4. 4 N/dm (4 oz/in)), when measured at an unwind speed of 0. 3 m/min, (preferably at unwind speeds of up to

30 m/min, more preferably at unwind speeds of up to 50 m/min) ; and B) exhibits a smooth unwind. Preferably the roll of tape exhibits a smooth unwind at unwind speeds up to about 30 m/min, more preferably at unwind speeds greater 30 m/min, most preferably at unwind speeds up to 50 m/min.

By"smooth unwind"it is meant that the unwind is not shocky. Smooth unwind is achieved when the holographic image is not damaged (e. g., distorted, creased, and combinations thereof) upon unwind. Damage to the holographic image manifests itself as noticeable alterations to the holographic image including, e. g., change in reflectivity, the presence of creases, e. g., creases extending in the transverse (i. e., cross) direction of the tape, and other distortions of the holographic image. Damage to the holographic image is determined under normal viewing conditions.

One measure of smooth unwind is the shockiness index ("SI"). The shockiness index is determined by taking the difference between the maximum unwind force (Pmax) and the minimum unwind force (Pmon) divided by the average unwind force (Pave) (SI = (Pmax - Pmjn)/ Pave) Preferred tape systems have a SI value of no greater than about 3, more preferably no greater than about 2, most preferably no greater than about 1 at unwind speeds of no greater than about 30 m/min.

The adhesive composition is selected such that it cooperates with the backing to yield a tape system having the aforementioned unwind characteristics.

Preferably the adhesive composition is suitable for box sealing applications such that a tape formed from the adhesive composition is capable of maintaining adhesion to packaging materials, e. g., cardboard and boxes, and exhibiting sufficient strength to seal boxes, i. e., maintain portions of a box in fixed relation with each other.

Preferably the adhesive composition is pressure-sensitive. Pressure- sensitive adhesives are normally tacky at room temperature and can be adhered to a surface by application of light finger pressure. Suitable adhesive compositions include, e. g., hot-melt coatable, transfer-coatable, solvent-coatable adhesive

compositions ; latex adhesive compositions ; and thermally-activated, water- activated, and radiation-activated adhesive compositions.

The adhesive composition can include, e. g., elastomeric block copolymers, natural rubber, butyl rubber and polyisobutylene, styrene-butadiene rubber (SBR), polyalphaolefins, and polyacrylates. Examples of useful thermoplastic elastomeric block copolymers include styrene-isoprene, styrene- isoprene-styrene, styrene-butadiene-styrene, ethylene-propylene-diene, styrene- ethylene/butylene-styrene (S-EB-S), and styrene-ethylene/propylene-styrene (S- EP-S). Examples of useful rubbers include polyisoprene, and polychloroprene.

Other useful adhesive compositions include, e. g., polyvinyl ether, ethylene containing copolymers such as, e. g., ethylene vinyl acetate, ethylacrylate, and ethyl methacrylate ; polyurethane, polyamide, epoxy, polyvinylpyrrolidone and vinylpyrrolidone copolymers, polyesters and combinations thereof.

A general description of useful pressure-sensitive adhesive compositions can be found in Encyclopedia of Polymer Science and Engmeenng, vol. 13, Wiley-Interscience Publishers (New York, 1988). Additional descriptions of pressure-sensitive adhesive compositions can be found in Encyclopedia of Polymer Science and Technology, vol. 1, Interscience Publishers (New York, 1964).

Useful block copolymer-based adhesive compositions are selected to exhibit a peel force of at least about 33. 5 N/dm (30 oz/in) (more preferably at least about 44. 6 N/dm (40 oz/in), most preferably at least about 55. 4 N/dm (50 oz/in) ) when measured on a steel substrate at room temperature pursuant to the 180° Peel Adhesion Test Procedure set forth in the Example section of this application.

Useful block copolymer-based adhesive compositions are also selected such that the resulting tape exhibits a shear strength to fiberboard of at least about 500 min, preferably at least about 750 min, more preferably at least about 1000 min, when measured according to Shear to Fiberboard Test Procedure set forth in the Example section of this application.

Preferred elastomeric block copolymer-based adhesive compositions include block copolymers such as, e. g., styrene-isoprene-styrene (SIS) and styrene

butadiene-styrene (SBS). Particularly useful block copolymers are available, e. g., under the product numbers 1107,1101, 1111, 1112 and 1117 from Shell Chemical Company under the Kraton trade designation, and under the Vector 4100 trade designation from Dexco Polymers.

Useful acrylate-based adhesive compositions are selected to exhibit a peel force of at least about 22. 3 N/dm (20 oz/in), more preferably 33. 5 N/dm (30 oz/in), most preferably at least about 44. 6 N/dm (40 oz/in) ) measured on a steel substrate at room temperature pursuant to the 180° Peel Adhesion Test Procedure set forth in the Example section of this application.

Examples of useful acrylate-based adhesive compositions are described in U. S. Patent No. 4, 594, 277 and Re 24, 906, and incorporated herein. The acrylate based adhesive composition can also include additives such as, e. g., chain transfer agents for controlling molecular weight, plasticizers, tackifiers, and crosslinkers.

The adhesive composition can also include additives such as, e. g., tackifiers, plasticizers, fillers, antioxidants, stabilizers, pigments, diffusing particles, curatives, fibers, filaments, and solvents.

Suitable tackifying resins include, e. g., rosin esters, terpenes, phenols, and aliphatic, aromatic, or mixtures of aliphatic and aromatic synthetic hydrocarbon monomer resins. The tackifier components useful in block copolymer adhesive composition can be either solid, liquid, or a blend thereof. Suitable solid tackifiers include rosin, rosin derivatives, hydrocarbon resins, polyterpenes, coumarone indenes, and combinations thereof. Suitable liquid tackifiers include liquid hydrocarbon resins, hydrogenated liquid polystyrene resins, liquid polyterpenes, liquid rosin esters, and combinations thereof. Useful commercially available tackifier resins include Wingtack 95 and Wingtack Plus available from The Goodyear Company, and Regalrez 1018 and 1078 from Hercules, Inc.

Suitable tackifier resins are described in D. Satas, Handbook of Pressure-Sensitive Adhesive Technology, pp. 527-544 (2nd ed. 1989).

The backing includes a holographic image. The holographic image can include two-dimensional images, three-dimensional images, and combinations thereof. The holographic image can be visible, quasi-visible (e. g., contains images

that have deliberate errors that are not readily apparent on inspection) or invisible to the naked eye. Invisible images are constructed by viewing the hologram at particular angles or under special light conditions using special scanning equipment. The holographic image can be formed by providing a metal, e. g., aluminum, on an embossed backing material. The metal can be provided on the backing by any suitable coating method including, e. g., vapor deposition. Suitable backing materials include, e. g., single and multiple layer plastic films including, e. g., polypropylene (e. g., monoaxially oriented polypropylene (MOPP), biaxially oriented polypropylene (BOPP), simultaneously biaxially oriented polypropylene (SBOPP) and combinations thereof), polyethylene, copolymers of polypropylene and polyethylene, polyvinyl chloride (PVC), polyesters, vinyl acetates, and combinations thereof. The backing material can be compostible, degradable, colored, printable, and printed, and can be of different surface textures, embossed, or extensible.

Preferred backing materials include polyester, monoaxially oriented polypropylene (MOPP), biaxially oriented polypropylene (e. g., BOPP and SBOPP), and other similar flexible plastic materials. Backings including holographic images can be obtained in a roll that has been previously metallized or unmetallized. The thickness of the material and the size of the roll in terms of length and width, the tension, the coating side, image pattern and image repeats of the backing can be selected according to user requirements. Some holographic backings have a thickness of 1/3 to 4 mils (8. 4 um to 100 um) or thicker. Suitable holographic backings are commercially available from a number of manufacturers including Foilmark, Van Leer and Spectratek.

The release properties of the backing can be modified such that the backing and the adhesive cooperate to achieve the aforementioned unwind characteristics. Examples of processes useful for modifying the release properties of the backing include application of a low surface energy composition, priming, corona discharge, flame treatment, roughening, etching, and combinations thereof.

In the case of low surface energy compositions, the low surface energy composition preferably is compatible with the adhesive composition and does not

degrade the adhesive properties of the tape such as by being transferred to the adhesive composition. Useful low surface energy compositions include, e. g., silicone (e. g., silicone polyurethanes, silicone polyureas and silicone polyurethane/ureas, such as, e. g., those described in U. S. Patent No. 5, 214, 119, U. S. Patent No. 5, 290, 615, U. S. Patent No. 5, 750, 630, and U. S. Patent No.

5, 356, 706, each of which is incorporated herein, epoxy silicones, acrylate functional silicones, silicone acrylate grafted copolymers described, e. g., in U. S.

Patent No. 5, 032, 460, U. S. Patent No. 5, 202, 190, and U. S. Patent No. 4, 728, 571, and U. S. Patent No. 4, 693, 935, and incorporated herein, and addition and condensation cured organopolysiloxanes such as, e. g., those described in European Patent Application 510, 200 Al, and incorporated herein), fluorocarbon copolymers, and long alkyl side chain copolymers such as polyvinyl carbamates (e. g., polyvinyl N-octadecyl carbamates) as described, e. g., in U. S. Patent No.

2, 532, 011, and copolymers containing alkyl acrylates where the alkyl side chain includes from about 16 to about 20 carbon atoms (e. g., octadecyl acrylate, stearlylmethacrylate-acrylonitrile copolymer, and polyvinyl esters, e. g., vinyl stearate, palmitate, arochidate and behenate).

Examples of suitable acrylate functional silicone release agents are described in U. S. Patent No. 5, 425, 991, U. S. Patent No. 5, 494, 979, and European Patent Application 624, 627A2, and are incorporated herein. Useful silicone- acrylate release agents are available commercially under the Tego trade designation including RC 726, RC 708, RC 711, RC 709, RC 715, RC 902, and RC 705 from Th. Goldschmidt Chemical Co.

Additionally, silicones can be modified with epoxy groups to make them more polar. Examples of suitable epoxy functional silicone-based low surface energy compositions are described, e. g., in WO 94/28080 and European Patent Application 464,706A1, and incorporated herein.

Organosiloxanes can also be blended with, e. g., nitrocellulose, alkyl ether maleic anhydride copolymers, and vinyl alkyl carbamate copolymers to increase the release force of silicone-based release agents. Silicones can also be

co-cured with isocyanates, polybutadiene, and acrylic emulsions to increase the release force of the silicone based release agent.

The tape can be made in a number of ways including, e. g., coating a layer of release composition onto a backing, curing the release layer, drying the release layer, and coating the adhesive composition onto the opposite surface of the backing ; and coating the adhesive composition onto a release composition present on a backing. The processes may be carried out separately or sequentially in-line.

Prior to either or both coating steps, the backing may be treated to enhance adhesion of the composition to the backing. Such treatments include priming, flame treatment, and corona treatment.

EXAMPLES Test Procedures Test procedures used in the Examples include the following.

Unwmd Force at High Speed Test Procedure The force required to unwind a 48 mm wide roll of tape at 30 m/min is measured using a Chemsultants International unwind machine having an unwind motor, a winder station, and the capability of electronically evaluating the unwind properties of the adhesive tape. The output is printed in the form of a graph showing the actual unwind force in N/dm as a function of distance along the tape.

The shockiness index (SI) is calculated from such graph as the ratio (maximum unwind force-minimum unwind force)/average unwind force.

Unwind Force at Low Speed Test Procedure The unwind force at a speed of 12 in/min (0. 3 m/min) is measured according to PSTC 8 (Pressure-Sensitive Tape Council, Chicago, Illinois). The unwind force is recorded in N/dm.

180° Peel Adheslon Test Procedure Peel adhesion is measured according to PSTC 1 from a stainless steel substrate at 12 in/min (0. 3 m/min). Results are recorded in N/dm.

Shear to Fiberboard Test Procedure Hanging shear failure times are measured according to PSTC 2. The adhered sample area is 1. 27 x 1. 27 cm and a weight of 1 kg is used. Time to bond failure is recorded in minutes.

Damage to the Foilmark 1/4"Mosaic Pattem Holo2raphic Ima2e and Foilmark City Lights Holographic Image Test Procedure A 20-30 cm strip of Foilmark biaxially oriented polypropylene film having a %"Mosaic pattern holographic image or a City Lights holographic image is held at chest level and the reflection of the overhead fluorescent ceiling lights is observed. The strip of film is then tilted in a 45 degree orientation to observe localized changes in reflectivity, creases, and other distortions of the image.

Example 1 A 1. 2 mil (30 um) thick Foilmark biaxially oriented polypropylene (BOPP) film having a'/4"Mosaic pattern holographic image (Foilmark Holographic Images a division of Foilmark, Inc. Newburyport, MA), was corona treated on the side opposite the image, and then coated with a LJV curable precursor of a low surface energy coating that included 70 parts by weight Tego RC 708 (Th. Goldschmidt AG, Esson, Germany), 30 parts by weight Tego RC 711 (Th. Goldschmidt), and 3 % Darocur 1173 UV photoinitiator (Ciba-Geigy) based on 100 parts by weight RC 708/711. The low surface energy composition was coated at a coating weight of the precursor of 0.5 g/m2 and then cured by UV radiation in a nitrogen atmosphere.

The image side of the holographic film was coated with a synthetic rubber resin pressure-sensitive adhesive composition that included 100 parts by

weight Kraton 1107 styrene-isoprene-styrene block copolymer (Shell), 85 parts by weight Wingtack Plus tackifier resin (Goodyear), 1. 5 parts Cyanox LTDP stabilizer (Ciba-Geigy), and 1. 5 parts by weight Irganox 1076 antioxidant (Ciba- Geigy), using standard hot-melt extrusion coating techniques. The adhesive composition was applied at a coating weight of 23. 0 g/m. The tape was rolled up onto itself, slit into 48 mm rolls and stored as described below to produce naturally aged tape rolls.

The tape of Example 1 was then subjected to the above-described Test Procedures, which were repeated three times and the results averaged. The results for the Unwind Force at High Speed Test were obtained on rolls of tape that had been naturally aged at 23 °C and ambient relative humidity for 75 days. Results for all other tests were obtained by testing rolls of tape within approximately 2 weeks of their manufacture. The results are reported in Table I. There was no visually perceptible damage to the holographic image of the samples of Example 1 that were tested at low and high unwind speeds.

Example 2 An adhesive tape was prepared according to Example 1 with the exception that the backing was a Foilmark BOPP film having a Foilmark City Lights holographic image (Foilmark), and the low surface energy composition included 80 parts by weight Tego RC 708 (instead of 70 parts), 20 parts by weight Tego RC 711 (instead of 30 parts), and 3 % Darocur 1173 UV photoinitiator (Ciba- Geigy) based on 100 parts by weight RC 708/711. Also, the low surface energy composition was coated at a coating weight of the precursor of 0. 6 g/m2 (instead of 0.5g/ m2).

The tape of Example 2 was then subjected to the above-described Test Procedures, which were repeated three times and the results averaged. The tests were performed on rolls of tape that had been stored at 23°C and ambient relative humidity for 24 hours. The results are reported in Table I. There was no visually perceptible damage to the holographic image of the samples of Example 2 that were tested at low and high unwind speeds.

TABLE High Speed (30 SI Low Speed Shear to 180° Adhesion m/mln) (0. 3 m/mm) Fiberboard (N/dm) Unwind Unwind (min) (N/dm) (N/dm) Example 1 0.371.2584246455.2 Example2 3. 12. 576658. 7 Other embodiments are within the claims. For example, the adhesive tape can exist in a variety of forms including, e. g., a roll, and a pad. The tape can also include information printed on or otherwise applied to the tape.

What is claimed is :