AU2006200606A1 - Writeable tapes - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor(s): Address for Service: Invention Title: Brian M. Elms Pty Ltd Brian Maxwell Elms DAVIES COLLISON CAVE, Patent Attorneys, 1 Nicholson Street, Melbourne, Victoria 3000.

"Writeable Tapes" Details of Associated Provisional Application(s): No(s): 2005900683 The following statement is a full description of this invention, including the best method of performing it known to me/us: Q:\OPERUcc\Arcbive\2006\Feb\12726520 044.doc 141106 P:\OPERUCCISPECIFICATIONS\WRTEABLE TAPES.doc.I402IO6 -1- WRITEABLE TAPES The present invention relates to adhesive tapes, to their manufacture and to their use.

Laminate adhesive tapes are used in many situations where it is desired to apply a label to goods. For instance, such tapes may be affixed to goods in order to indicate that the goods have been found to satisfy some requirement or test standard. Such tapes usually include printed information and are required to be writeable with conventional rapid-drying spiritbased marker pens. Such pens are used to include additional information on the tape surface. For instance, the label may be printed with a series of boxes relating to such things as dispatch date, part no. etc. and these boxes are filled in as necessary by hand with a marker pen. When the tape is written on in this way the pen should leave a durable image which is not easily removed or degraded. These kinds of tapes are usually subjected to handling and/or may be exposed to the elements so that the durability of information written on the tape is important.

Conventional tapes of this kind comprise a number of layers and are thus provided as a laminate. One layer of the tape (the backing or carrier layer) includes an adhesive on one side and the other side is printed on. On top of this printed information is provided a transparent cover layer. This form of tape is usually provided in the form of a roll with sections of the tape being pulled from the roll as and when needed. The cover layer prevents the adhesive from stripping the printed information from the backing layer when the tape is withdrawn from the roll. It is this cover layer that will be written on when the tape is used.

Various problems can be encountered with this type of writeable laminate tape. One such problem is that delamination tends to occur when lengths of tape are pulled from a roll.

This occurs because the inter-layer bond strength between the cover layer and carrier layer in the laminate is less than the bond strength between the adhesive and cover layer when the laminate is provided as a roll. The result is that, when one attempts to withdraw a length of tape from the roll, the cover layer separates from the carrier layer.

PAIOPERUCC\SPECIF[CATIONS\WRITEABLE TAPES do.14/2106 -2- Some manufacturers prefer to use a gloss finish on the cover layer as this reduces the tack of the adhesive with respect to the cover layer, and thus the un-rolling forces required to dispense the tape. In turn this reduces the risk of delamination. However, writing on the surface of this kind of tape tends not to be sufficiently durable since the gloss layer is relatively impervious to the ink used in marker pens. It would be desirable to solve the delamination/un-rolling problem without using a gloss finish on the cover layer, as this will bring with it advantages in terms of durability of information written on the tape surface with a marker pen.

Another solution to the delamination problem is to include a parting strip (or backing tape) between adjacent layers of tape in a roll, i.e. between the adhesive layer of one layer of tape and the cover layer of the layer of tape immediately below. The parting strip prevents bonding of the adhesive and cover layer whilst also being made of a material which the adhesive does not bond to strongly. The parting strip is removed as the tape is dispensed and used. This solution works and allows an ink receptive cover layer to be used.

However, this approach adds to production costs and complexity.

It would be desirable to solve these problems by producing a laminate adhesive tape which does not suffer delamination and which may be dispensed from a roll without excessive force, which is writeable using a marker pen with the resultant written information being durable, and which is inexpensive and easy to manufacture.

Accordingly, in one embodiment the present invention provides a writeable laminate adhesive tape comprising: a carrier layer; a layer of adhesive provided on one side of the carrier layer; a cover layer provided on the other side of the carrier layer; and a layer of adhesive between the carrier layer and cover layer, wherein the cover layer comprises a release agent comprising a fluorocarbon polymer.

P:\OPERUCC\SPECIFICATIONS\WRITEABLE TAPES.doc..4/02/06 -3- In accordance with the present invention it has been found that use of the release agent as defined avoids the delamination and dispensing problems described above without compromising the writeability (in terms of durability) of the tape. This is believed to be due to the fact that the release agent reduces the affinity of the adhesive for the material of the cover layer. In turn this allows the tape to be dispensed from a roll with greater ease since the pull out force required to withdraw a length of tape from the roll is reduced. This may allow advantageous modifications in the equipment usually employed to dispense a tape from a roll since reduced pull out force (reduced drag) may allow more lightweight dispensing equipment to be used. Additionally, a reduction in pull out force may allow relatively wider tapes to be used since the pull out force is directly related to surface area of the tape. The present invention may therefore facilitate use of much wider tapes than are currently employed. By way of illustration, if the effect of the release agent is to halve the adhesive tack between the adhesive and the material of the cover layer, it may be possible to double the width of the tape whilst retaining the ease with which the tape may be dispensed from a roll.

Furthermore, use of a release agent in accordance with the present invention may actually enhance the writeability (in terms of image durability) of the tape when a conventional spirit-based pen is used. It has been found in accordance with the present invention that the writeability of a tape may be enhanced, irrespective of the surface finish of the tape surface (cover layer). Thus, in accordance with the invention enhanced writeability may be observed with tapes having a matt or gloss finish.

The materials used in the present invention for the adhesive, carrier and cover layers are conventional in the art, and one skilled in the art will be familiar with suitable materials that may be used. The adhesive is usually a pressure sensitive rubber/resin or acrylic adhesive. The carrier layer can be any one of a wide range of materials that can be formed into a thin, flexible film. Frequently used materials include polymerics, such as PVC and polypropylene, and cellulose-based materials, such as paper. It is also possible to use metallic or textile materials. The use of polymeric materials is preferred. Often the carrier P:\OPER'JCC\SPECIFICATIONS\WRITEABLE TAPESdoc-14/026 -4layer is coloured, and this may be achieved by conventional means. The cover layer is a transparent (but possibly coloured) layer as is conventionally used in writeable laminate tapes. The cover tape may have a matt or gloss finish. The carrier layer and cover layer are bonded to each other using an adhesive, and conventional adhesives may be used. The thickness of each of the layers is entirely conventional too; the invention resides in the use of the release agent rather than the material from which other layers of the tape are made.

In accordance with the present invention the cover layer comprises a release agent that comprises a fluorocarbon polymer. Usually, the polymer will be formulated for use as a composition with various other components, such as solvents, binders etc. The presence of such components on the laminate tapes of the present invention may also contribute to the advantageous technical effects associated with the present invention. It is of course possible however that components originally present in a polymer formulation that is used for forming the release agent will not actually be present in a finished laminate tape in accordance with the present invention. Solvents for example may be driven off during formation of the release agent.

The release agent may be provided in a variety of forms. In one embodiment, the release layer is provided as a discrete layer on top of the cover layer. In this embodiment the release agent is usually applied as a continuous, uniform layer.

In another embodiment, particles of release agent may be provided on the surface of the cover layer. Such particles may be dusted onto the cover layer whilst the latter is tacky (during tape manufacture), or some form of adhesive may be used to ensure that the particles are retained in place on the surface of the cover layer. In another embodiment a composition comprising the release agent may be applied, e.g. by spraying, onto the cover layer, with (volatile) components in the composition then being driven off, e.g. by drying, resulting in particles (or crystals or precipitate) of the fluorocarbon polymer on the surface of the cover layer. These particles, or the like, may adhere to the cover layer due to the presence of one or more components that are present in the composition and that effectively function as an adhesive between the particles and the cover layer. Thus, in this P:\OPERUCC\SPECIFICATIONS\WRITEABLE TAPES doc-14102106 embodiment the cover layer comprises particles of the release agent adhered to the (outer) surface of the cover layer.

In another embodiment, the release layer may be incorporated into the material from which the cover layer is formed so that, when provided as a thin film, the cover layer would include the release agent as an integral component. The cover layer is invariably polymeric and in this embodiment the release agent may be blended with a hot melt of the polymer prior to formation of the cover layer as a thin film.

The viability of each of these embodiments may vary between different release agents/release agent compositions.

Herein the term fluorocarbon polymer is intended to mean organic polymers which include fluorine. The polymer may also include other hetero-atoms, such as chlorine, and the term is also intended to extend to such polymers. A variety of fluorocarbon polymers may be suitable for use as the release agent in accordance with the present invention, and it will be straightforward for one skilled in the art to assess the viability and usefulness of any given polymer taking into account the following points. In an embodiment of the invention the fluorocarbon polymer is polytetrafluoroethylene (PTFE).

Firstly, the fluorocarbon polymer must impart the desired technical effect when used as a release agent in accordance with the present invention. This means that the release agent must be capable of reducing the adhesive tack between the (pressure sensitive) adhesive used in the tape and the material of the cover layer. It is also important however that the release agent does not deleteriously affect the writeability of the cover layer (with a conventional type of spirit-based marker pen). In this context the term writeability means the ability of the surface of the cover layer to receive ink during the writing process and retain the ink so that written information is durable and not easily removed, for example by rubbing by hand.

Secondly, the release agent must be one which is capable of being applied to or P:IOPERUCC\SPECIFICATIONS\WRITEABLE TAPES dom.14/02J6 -6incorporated into the cover layer with ease. Techniques which may be employed to achieve this are described above. Thus, when the release agent is provided on the cover layer as a layer itself, the release agent and cover layer must be compatible in the sense that the release agent is capable of wetting the cover layer so that coverage of the cover layer is essentially uniform. It may be possible to enhance the stability of the release agent on the cover layer by use of a coupling agent, but this is not especially preferred as it will add to production costs and complexity.

Finally, to be useful in practice, the release agent should be in a form which is convenient and simple to use, and economically viable. Desirably, application of the release agent is accomplished with minimum disruption to the conventional methodology by which writeable laminate tapes are usually manufactured.

As noted, the release agent will usually be formulated as a composition in combination with other ingredients as might be necessary to permit the composition to function as necessary. Thus, the polymer itself will normally be hydrophobic and one or more organic solvents may be required to solublise the polymer. This said it may be possible to use aqueous systems incorporating the polymer. In this case the polymer is likely to be formed by emulsion polymerisation methods, as are well known in the art. If the release agent is provided in sprayable form, conventional propellants etc. will be included. Desirably, the release agent will be provided as a composition which may be printed onto the cover layer.

In this case conventional components found in printable compositions may be present, such as binders etc.

Given these guidelines it is believed that one skilled in the art will have no difficulty in selecting a fluorocarbon polymer or in formulating it for use as a release agent for use in practice of the invention. It has been found that the present invention works well using polytetrafluoroethylene (PTFE) as the fluorocarbon polymer. PTFE is available commercially in a number of different forms and products. As an example of a commercially available product that has been found to be useful is CRC Dry Glide with Teflon®. This is available in aerosol form for spraying. Surprisingly, it has been found P:\OPERUCC\SPECIFICATIONS\WRITEABLE TAPESdo.1402/06 -7that as well as solving the delamination problem described above, use of this product may lead to enhanced writeability in terms of durability of written information/image.

The exact mechanisms by which the effects of the invention are achieved are not understood in detail. With respect to preventing delamination it seems reasonable to say that the release agent must reduce the adhesive tack between the adhesive and cover layer materials. Without wishing to be bound by theory, this may be as a result of the adhesive stripping (particles or the like) the release agent from the cover layer with relative ease so that the adhesive bond between the cover layer and carrier layer is not stressed when the tape is dispensed from a roll. Alternatively, it is possible that the fluorocarbon polymer in the release agent results in a surface which is of relatively low binding affinity with respect to the adhesive.

It is even less well-understood how enhanced writeability (durability) may be observed when a release agent is used in accordance with the present invention. Without wishing to be bound by theory, it is believed that the resultant layer comprising the release agent may be ink permeable so that the ink can be absorbed onto the surface of the cover layer, after which the release agent acts as a barrier preventing removal of the ink. Again, without wishing to be bound by theory, it may be the case that particles, or the like such as crystals, of the release agent provide surface relief effects on the surface of the cover layer. Thus, when applied, ink can penetrate between particles and onto the cover layer itself but thereafter the particles prevent removal of the ink, for example by rubbing of the tape surface, because they prevent the ink itself from being contacted directly.

Irrespective of the exact mechanism by which embodiments of the invention work to achieve the beneficial effects of the present invention, the fact that enhanced writeability (durability) may be observed with a tape in accordance with the invention which has been unwound from a roll suggests that the release agent, or at least a portion of it, is retained on the cover layer. Enhanced writeability with cover layers having a matt or gloss finish has been observed using the PTFE-based product mentioned above, i.e. CRC Dry Glide with Teflon®.

P:\OPERUCC.SPECIFICATIONS\WRITEABLE TAPES.d.-1402106 -8- In the following particular reference is made to forming the release agent as a discrete layer on the cover layer. Other methods as described are of course equally possible.

A laminate tape of the invention may be manufactured by conventional techniques, such as coating, rolling, and slitting, and the release agent applied, for example by spraying, brushing or printing depending upon the nature of the release agent involved, as the tape is wound into a roll. The release agent should be allowed to dry before rolling takes place.

Drying may be enhanced by blowing warm air onto the release once applied or by the use of radiant heat. The amount/thickness of the release agent applied may vary depending on, amongst other things, the type of adhesive and cover layer used and possibly the rate at which the tape is wound between rolls during manufacture... The amount/thickness of the release agent may be optimised by simple trial and error.

In one aspect of the present invention, the method involves manufacturing the laminate tape from start to finish. However, it is also possible in accordance with the invention to treat a pre-existing laminate tape to include a release agent. This may be done by applying the release agent to the cover layer of the tape as it is transferred between rolls. The various techniques described may be used here.

The laminate tapes of the invention may be used in any of the variety of applications which such tapes are conventionally used. The fact that the tapes of the invention exhibit enhanced durability when written on using a spirit-based marker pen may mean that the tapes of the invention are more especially suited to applications where marking durability is likely to be an essential characteristic, for example if the goods being labelled with the tape are likely to be handled or inspected frequently and/or exposed to the elements, i.e. to weathering. The invention extends to all such uses, and to labels, tags and the like, comprising the writeable laminate tape of the invention as disclosed herein.

In another embodiment the present invention relates to improvements in so-called single layer adhesive tapes that consist of a carrier layer and a layer of adhesive provided on one P:\OPERUCCSPECIF[CATIONS\WRITEABLE TAPES dom-14/0206 -9side of the carrier layer. Packaging tapes, and the like, are typically produced as single layer tapes. In such single layer tapes the carrier layer is generally thicker than the carrier layer in laminate adhesive tapes since in single layer tapes increased tensile strength is required to maintain the integrity of the tape when the tape is being unwound. If the carrier layer exhibits insufficient tensile strength, the carrier layer may tear or rupture on unwinding due to the adhesive tack of the adhesive. For this reason also the carrier layer is typically formed of PVC for strength.

Furthermore, the industry does not usually provide single layer tapes as pre-printed since print (ink) applied to the carrier layer tends to be stripped away from the carrier layer when the tape is unwound.

In accordance with an embodiment of the present invention it has been found possible to provide single layer adhesive tapes that overcome the disadvantages described above.

More specifically, it has been found that application of a release agent, as described herein, to the carrier layer of a single layer adhesive tape may reduce the adhesive tack as between adjacent layers of tape provided on a role. In turn this may allow the production of preprinted tapes that do not suffer the print-stripping problem mentioned above. Use of a release agent as described herein may also facilitate the use of carrier layer materials of reduced thickness and/or the use of different types of carrier layer materials, due to the fact that the release agent provides reduced adhesive tack as between the carrier layer and adhesive.

Accordingly, in another embodiment of the present invention, there is provided a writeable adhesive tape consisting of a carrier layer and a layer of adhesive provided on one side of the carrier layer, wherein the carrier layer comprises a release agent comprising a fluorocarbon polymer provided on a surface of the carrier layer remote from the layer of adhesive.

The carrier layer and adhesive may be formed of conventional materials as described herein in relation to the laminate adhesive tapes of the present invention. The release agent P:%OPERUCC\SPECIFICATIONS\WR!TEABLE TAPESdo-14/OM6 used in this embodiment of the invention is as described above in relation to the laminate tapes.

In this embodiment the adhesive tape is a single layer tape and, as such, consists only of a carrier layer, an adhesive layer and release agent. The carrier layer may be pre-printed with information and/or graphics, or the like. Desirably, the adhesive tape of this embodiment of the invention is writeable and the release agent is believed to enhance writeability (in terms of image durability) as described herein in relation to the laminate adhesive tapes. Explanations as to the likely mechanisms by which this effect is achieved are outlined above.

With respect to this latter embodiment of the invention there is also provided a method of making a writeable adhesive tape which comprises making a single layer adhesive tape consisting of a carrier layer and a layer of adhesive provided on one side of the carrier layer, and applying the carrier layer a release agent comprising a fluorocarbon polymer as the tape is being wound into a roll.

As a variation of this method a single layer adhesive tape in accordance with the present invention may be made by transferring between rolls an adhesive tape consisting of a carrier layer and a layer of adhesive provided on one side of the carrier layer and applying to the carrier layer a release agent comprising a fluorocarbon polymer as the tape is transferred between rolls.

In these methods the release agent may be applied as described above in relation to the laminate adhesive tapes of the invention.

The present invention also provides single layer adhesive tapes when made by either of the methods described above.

The invention also relates to a label or tag or the like comprising a single layer adhesive tape of the present invention. Furthermore, the invention extends to the use of single layer P:%OPERUCC SPECIFICATIONS\WRITEABLE TAPESdo-1410V06 11 adhesive tapes of the present invention to label goods that are likely to be handled or inspected frequently and/or exposed to the elements. These single layer adhesive tapes may also be useful as packaging tapes.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (28)

1. A writeable laminate adhesive tape comprising: a carrier layer; a layer of adhesive provided on one side of the carrier layer; a cover layer provided on the other side of the carrier layer; and a layer of adhesive between the carrier layer and cover layer, wherein the cover layer comprises a release agent comprising a fluorocarbon polymer.

2. A writeable laminate adhesive tape according to claim 1, wherein the carrier layer is formed of a polymeric material.

3. A writeable laminate adhesive tape according to claim 1 or 2, wherein the release agent is provided as a layer on the cover layer.

4. A writeable laminate adhesive tape according to claim 1 or 2, wherein the cover layer comprises particles of the release agent adhered to the surface of the cover layer.

A writeable laminate adhesive tape according to any one of the preceding claims, wherein the fluorocarbon polymer is polytetrafluoroethylene.

6. A method of making a writeable laminate adhesive tape as claimed in claim 1, which method comprises making a laminate adhesive tape comprising a carrier layer, a layer of adhesive provided on one side of the carrier layer, a cover layer provided on the other side of the carrier layer and a layer of adhesive between the carrier layer and cover layer, and applying to the cover layer a release agent comprising a fluorocarbon polymer as the tape is being wound into a roll.

7. A method according to claim 6, wherein the release agent is applied by spraying, brushing or printing. P: OPER\CC\SPECIFICAT[ONS\WRITEABLE TAPES.doc.14/02/06 -13-

8. A method of making a writeable laminate adhesive tape as claimed in clam 1, which method comprises transferring between rolls a laminate adhesive tape comprising a carrier layer, a layer of adhesive provided on one side of the carrier layer, a cover layer provided on the other side of the carrier layer and a layer of adhesive between the carrier layer and cover layer, and applying to the cover layer a release agent comprising a fluorocarbon polymer as the tape is being transferred between rolls.

9. A method according to claim 8, wherein the release agent is applied by spraying, brushing or printing.

A writeable laminate adhesive tape according to claim 1 substantially as hereinbefore described.

11. A method of making a writeable laminate adhesive tape according to claim 6 or claim 8 substantially as hereinbefore described.

12. A writeable laminate adhesive tape when made by a method as claimed in any one of claims 6 to 9 and 11.

13. A label or tag comprising a writeable laminate adhesive tape as claimed in any one of claims 1 to 5, 10 or 12.

14. Use of a writeable laminate adhesive tape as claimed in any one of claims 1 to 5, or 12 to label goods that are likely to be handled or inspected frequently and/or exposed to the elements. A writeable adhesive tape consisting of a carrier layer and a layer of adhesive provided on one side of the carrier layer, wherein the carrier layer comprises a release agent comprising a fluorocarbon polymer provided on a surface of the carrier layer remote from the layer of adhesive.

P:NOPERJCCSPECIFICATIONS\WRITEABLE TAPES.d-14/02/06 -14-

16. A writeable adhesive tape according to claim 15, wherein the carrier layer is formed of a polymeric material.

17 A writeable adhesive tape according to claim 15 or 16, wherein the release agent is provided as a layer on the carrier layer.

18. A writeable adhesive tape according to claim 15 or 16, wherein the carrier layer comprises particles of the release agent adhered to the surface of the carrier layer.

19. A writeable adhesive tape according to any one of claims 15 to 18, wherein the fluorocarbon polymer is polytetrafluoroethylene.

A method of making a writeable adhesive tape as claimed in claim 15 which comprises making a single layer adhesive tape consisting of a carrier layer and a layer of adhesive provided on one side of the carrier layer, and applying to the carrier layer a release agent comprising a fluorocarbon polymer as the tape is being wound into a roll.

21. A method according to claim 20, wherein the release agent is applied by spraying, brushing or printing.

22. A method of making a writeable adhesive tape as claimed in claim 15 which method comprises transferring between rolls an adhesive tape consisting of a carrier layer and a layer of adhesive provided on one side of the carrier layer and applying to the carrier layer a release agent comprising a fluorocarbon polymer as the tape is transferred between rolls.

23. A method according to claim 22, wherein the release agent is applied by spraying, brushing or printing.

24. A writeable adhesive tape according to claim 15 substantially as hereinbefore described.

P:OPERUCC.SPECIFICATIONS\WRITEABLE TAPES dc14/0206 A method of making a writeable adhesive tape according to claim 20 or claim 22 substantially as hereinbefore described.

26. A writeable adhesive tape when made by a method as claimed in any one of claims 20 to 23 and

27. A label or tag comprising a writeable adhesive tape as claimed in any one of claims to 19, 24 or 26.

28. Use of a writeable adhesive tape as claimed in any one of claims 15 to 19, 24 or 26 to label goods that are likely to be handled or inspected frequently and/or exposed to the elements. DATED this 14 TH day of February 2006 Brian M. Elms By DAVIES COLLISON CAVE Patent Attorneys for the Applicant