The present invention concerns the production and application of linerless labels.

BACKGROUND OF INVENTION

A standard pressure sensitive label material has a multi-laminate structure composed of four critical elements: a face or face-stock (typically a paper or filmic substrate), an adhesive (typically a pressure sensitive adhesive), a release liner system, commonly comprising a silicone coating on a paper or polymeric liner. This label material, which is commonly produced in roll form, is converted into individual labels, which may then be applied to an article by an end-user, via the following typical process steps:i. The upper surface is printed with information and graphics, commonly describing and advertising the product contained within the article to be labelled. This printing is typically done on a continuous (roll-to-roll) narrow web press producing many labels across and along the web of the label material.ii. The upper parts (face material and adhesive) of the label material are then die-cut to produce individual labels carried in roll form supported by the release liner. Typically, but not necessarily, die-cutting is performed on the same asset (typically known as a press) as that used to print the labels.iii. The printed die-cut label material is then slit to provide single lanes of labels and these slit rolls are then sent to an end-user who will affix the labels to articles via a dispensing process described in (iv) below.iv. Labelling occurs at the end user by feeding the die-cut label material to a dispensing machine wherein labels are removed one at a time from the release liner and applied to the articles to be labelled. The release system allows the adhesive-backed labels which require a minimum level of stiffness, to be removed easily from the liner. This is typically a continuous operation running at high speeds (30-1,000 labels per minute) in which articles to be labelled are presented continuously to the dispensing point where they are labelled.v. The liner, coated with a release system, becomes a waste stream. This waste stream is collected on a rewind stand following dispensing and may subsequently be land-filled or sold into low value reprocessing.

The above process has existed for more than 50 years, and whilst it has undergone continuous improvement throughout this time with, for example, the use of thinner face and liner materials and the use of lower coat weights for the adhesive and release system, the basic construction has remained unchanged. During this time frame, the industry has developed enormous scale with the adhesive often coated on a wide web (up to 2-3 meters in width) of release coated liner at very high speeds, often well in excess of 1,000 meters per minute. The adhesive, coated on the release coated liner, is laminated to the face (filmic substrate or paper) web in the same process, forming the label material which is supplied to printer/converters. Most label materials are manufactured this way through what is commonly known as a transfer coating process, so called because the adhesive is transferred to the face material from the release liner.

The adhesive can also be directly coated on the face material, followed by laminating with the release coated liner, commonly known as a direct coating process. That said, for many years, the industry has sought to find ways to effect labelling of pressure sensitive materials without using a liner and associated release system, thus significantly improving material and supply chain efficiencies, reducing cost, and eliminating an increasingly problematic waste stream. The so called ‘linerless’ solution has proved to be very elusive. Typically, approaches to linerless solutions have fallen into one of two broad categories, “Activatable Labels” and “Liner-free Labels”.

Activatable Labels involve applying a specialty coating or cover layer to the adhesive system (essentially replacing the liner and the release system) or employing an adhesive system which is non-tacky at room temperature. In these solutions, a separate process, just prior to labelling, either removes the coating or cover layer to ‘unmask’ the adhesive, or activates the adhesive through an external stimulus such as heat or liquid. Activatable labels are supplied to the end user in a non-tacky state, and activated, i.e. the adhesive is exposed or activated to a tacky state just prior to application to the intended article. Activatable labels are printed prior to activation. By far, the most common activation scheme utilizes heat activation.

Whilst activatable label schemes do indeed eliminate the liner and the release system, and, therefore eliminate a waste stream, they replace them with another, often more expensive material, add complexity, and do not meaningfully improve cost. The cost issues arise from the use of expensive components in a specialty coating which masks the adhesive, or from the use of expensive additives or process to create a non-tacky adhesive. The requirement for additional process assets to remove the coating or activate the adhesive adds further cost to the overall solution, and separating an individual label at the point of dispensing remains challenging without the use of a carrier web. As discussed, earlier approaches to separating each label at the dispensing point exist, but add cutting complexity and the cost of such activatable label solutions do not justify end-users engaging in this additional complexity.

Due to the complex formulations needed to render an activatable adhesive non-tacky when wound in a reel, the adhesive after activation is commonly hazy in appearance which we define in this context as less than transparent. If the adhesive is hazy, a meaningful part of the label market, the so-called ‘clear-on-clear’ label, cannot be provided. In clear-on-clear systems, a label comprising a clear printed filmic substrate and a clear adhesive is applied to an article and, due to the transparency of the clear printed filmic substrate and clear adhesive, only the print is evident allowing a consumer to see product beneath the label. If the adhesive is hazy, then the appearance of the label becomes unacceptable.

Liner-free labels, while eliminating the liner, retain a silicone release system, and thus do not fully deliver the potential cost reduction. A liner-free system typically begins with printing of the face stock and then applying a release system (typically silicone based UV cured under a nitrogen blanket) to the printed face before coating the reverse side with a pressure sensitive adhesive to create a self-wound label material that does not include a liner. Typically a self-wound label material is produced on narrow web presses using an expensive adhesive, often a UV-cured hot melt, at a speed considerably lower (well below 1,000 meters per minute) than that used in conventional adhesive coating described above. The cost accumulation of lower scale, higher cost adhesive, and the continued use of a silicone release system mean that much, and sometimes all, of the cost benefit relative to the traditional process of eliminating the liner, is lost. The application of a silicone release coating to the printed face, either directly or by over-lamination of a clear filmic release liner, limits decorative options, for example tactile screen print or special varnishing effects.

Since the label printer is required to make additional investments to apply a conventional silicone release system and coat the adhesive, alternative processes have been developed whereby a clear release liner supplied as part of a conventional label material is transferred from the adhesive side of the face stock and then laminated over the printed face in either a modified narrow web press or a separate finishing machine, before die cutting or slitting the web to produce individual reels of labels. An example of such an alternative process may be found in Ritrama patent number EP2958743B1. Depending on the logistics, this process may provide a lower production cost solution for the printer. However, it only delivers minimal overall savings based on use of thinner face materials and also restricts decorative options.

A further challenge facing such a liner-free approach is to create individual labels from the label material (hereinafter referred to either as ‘singulation’ or ‘separation’) at the point of dispensing by the end user. Since there is no liner to carry the pre-die-cut labels to the dispensing point, singulation can only occur at the point of dispensing. One approach to this challenge is offered by ETI Converting Equipment (“ETI”). After creating the self-wound printed reel of labels, ETI deals with the singulation issue by using a temporary re-usable liner at the dispensing point. This allows a label to be die cut from the web in the label applicator, separated, and subsequently carried to the dispensing head by the temporary re-usable liner. This reduces the cost benefit of the ETI solution since a liner is re-introduced, adding complexity to die-cutting, and transferring to the end user the task of die-cutting perfectly repeatable shaped labels, currently the responsibility of the label printer/converter.

Another approach to solving the dispensing problem of a liner-free adhesive system has been described by Catchpoint® (e.g WO2009030893A1, to Cooper, et al.) in which labels are ‘weakened’ within the web prior to dispensing. In this scheme, the labels within the web are both shaped and weakened by perforations between each label. This ‘weakening’ is typically by traditional die-cutting, so that weakened self-wound material can be provided to the end user in a state ready to use and still in conventional roll form. The line of weakening for each label includes apertures which provide for engagement by a tool at the time of dispensing in order to break the weakened area and thus separate the leading label in the web for application to an article. In this scheme, the self-wound web carries the label to the dispensing point where labels are applied from the web. Whilst such schemes solve the dispensing challenge, they have seen limited adoption because the cost benefit (as discussed above) of the total solution does not justify the additional investment in new final web control and separation tools in the label applicator. On board linerless cutting systems within a label applicator such as that developed by, and branded as Monoweb®, and the ETI system described above, add a responsibility that end users have not accepted.

To carry out die cutting of Catchpoint® linerless labels, either coated with adhesive and silicone release, or by liner transfer, it is essential to either reverse the conventional format to cut through from the adhesive side, or use a process liner. Where liner transfer is used, systems have been proposed which die cut through to a clear PET liner before it is separated from the adhesive side of the web and subsequently transferred and laminated to the face of the web. This requires the die tool to cut through the transferred PET liner and the face material to itself. This has the inherent risk of damage to what becomes the finished label surface. Catchpoint® technology thereby provides perfectly repeatable label shaping to be reliably obtained.

A linerless label material and apparatus for applying labels die-cut from the linerless label material has been described by Patel in WO2007/015264 wherein the pressure sensitive adhesive is protected with a pre-formed water-soluble film wherein the thickness of the pre-formed water-soluble film ranges from 5 microns to 40 microns, preferably from 10 microns to 30 microns, more preferably from 15 microns to 20 microns. This has failed to achieve commercial success as it has proved impossible to remove a pre-formed water-soluble film of said thickness within the proposed label-cutting and application process.

In a subsequent application, US2012/061014, Patel describes the use of a water-soluble film of less than 5 microns, but none of the described coating methods provide a means to produce a water-soluble coating of said thickness. Patel further teaches in both documents die-cutting the labels in a label applicator after removal of the water soluble coating. This requires the die tool to cut through the label material from the exposed adhesive coated side.

Die-cutting through a label material from the adhesive side as taught by Patel requires the undercut of the die tool to be release coated and furthermore, it is impossible to protect the die cutting face which needs to touch the anvil to ensure cut through, reducing die life as well as in process risk of unpredictable failure.

Shibano U.S. Pat. No. 4,624,839 teaches the use of starch derivatives in a release layer for self-wound adhesive tapes wherein, however, the release layer is not removed to expose the pressure sensitive adhesive as in the present invention.

Avery Dennison describes a bottle labelling invention in US2014065334/U.S. Pat. No. 9,605,183 in which a silicone release coating on a liner is replaced with a polyvinyl alcohol water-soluble “release agent” of thickness 0.1 to 5 microns on a liner in order that the liner may be recycled after removal from “an adhesive article”. Paragraph [0027] states that “A release liner is coated with an amorphous PVOH polymer layer and applied to the PSA layer so that the amorphous PVOH layer is disposed between the PSA layer and the release liner”. The liner is retained in providing “an adhesive article”, the application process of which to a container is not described. No “adhesive article” as described by this invention has been commercialised which reflects a number of limitations which are addressed by the present invention, including a linerless label material, and a means of removal of a water-soluble coating within an acceptable time interval.

THE PRESENT INVENTION

According to one aspect of the present invention there is provided a method of applying a linerless label to an article including the steps ofi) providing a web of joined labels having a defined shape from a web of label material wherein both liner and its release layer have been eliminated wherein the adhesive is protected by a water-soluble coating;ii) at least partially removing the water soluble coating from the adhesive of the web of joined labels by exposure to water;iii) applying a label from the web of joined labels to an article wherein the label is separated from the web of joined labels by separation from an adjoining label at a boundary between the label and the adjoining label.

The present invention provides a method in which a silicone coated liner is replaced by a water-soluble coating.

It may be that conversion of the web of label material is carried out by die-cutting wherein the water soluble coating provides a cushion between an anvil and die cutting means during die cutting of the web. That is to say, die-cutting is made from the face material side of the label material. The label material wherein the adhesive is protected by the water soluble coating will thus pass over a conventional anvil with no risk of binding.

The face material is cut through before the die tool cuts into the adhesive layer. Current practice for conventional labels is to cut through to the silicone release coating of the liner, ensuring that the silicone coating of between 0.6 and 1 micron is not compromised during die-cutting provoking damage to the liner, since this can lead to labels not releasing in the applicator or the liner breaking. The use of a process liner to die-cut joined labels is subject to these same limitations, hence an unpredictable number of times that a process liner can be re-used. The water soluble coating of the present invention provides a novel replacement for a silicone coated release liner, reducing the cost of production and eliminating waste liner whilst still meeting or enhancing the process tolerance demands of die-cutting.

It may be that the boundary between the label and the adjoining label is weakened, for example perforated, such that the cohesion established by the adhesive between a partially applied label and an article being labelled is sufficient to break the weakened boundary. Alternatively, the boundary between a label and an adjoining label is cut as the label is sequenced for application to the article.

It may be that the method further includes the steps of rewinding and unwinding the web of joined labels between step (i) and step (ii) and/or between step (ii) and step (iii).

It may be that the method further comprises printing a top surface of the web of label material before removing the water soluble coating.

It may be that the method further includes providing a release coating on the top surface of the web of label material or the web of joined labels derived therefrom before or after printing the front surface.

It may be that the face material is selected from paper or polymeric substrates.

It may be that the adhesive is a self adhesive, for example a pressure sensitive adhesive.

It may be that the water soluble coating is based substantially upon polyurethane or polyvinyl alcohol polymers.

It may be that the label material comprises a face material, pressure sensitive adhesive and water-soluble coating.

It may be that the water soluble coating has a thickness of 3 to 7 microns, more preferably 4 to 5 microns.

It may be that the time interval during which the web is exposed to water is less than 10 seconds, more preferably less than 5 seconds.

It may be that the temperature of the water is between 5° to 50° C., preferably 10° to 30° C., more preferably 15° to 25° C.

It may be that the water-soluble coating contains anti-counterfeit means that may be subsequently identified overtly and/or covertly.

It may be that the label material can be produced by simultaneous or sequential coating and curing of a pressure sensitive adhesive and a water-soluble coating. The selection between simultaneous or sequential coating and curing will depend upon the characteristics of the pressure sensitive adhesive and the water-soluble coating.

Simultaneous dual layer “wet-on-wet” coating provides an original use of this combination of coatings and provides a label material including the following benefits:1. The use of dual layer coating equipment allows label face materials to be coated either by direct coating where a water-soluble coating is coated on top of a pressure sensitive adhesive, or by transfer coating from a process liner where a pressure sensitive adhesive is applied on top of a water-soluble coating, prior to lamination to a face material and rewind of the process liner.2. The label material may be produced in wide web coating equipment at high speeds using essentially the same assets as currently used and may be subsequently slit into widths required by the label printer.3. By this means, the manufacturer's production cost and waste disposal cost are dramatically improved over traditional label material manufacturing methods. Reduction in the caliper of face materials may also be practised in order to reduce manufacturing cost as linerless labels produced by the present method do not require the stiffness, and hence caliper, of conventional labels released from a release liner during application. Label material manufacturers are able to eliminate the use of a liner (typically a filmic liner of 19 to 30 μm thickness) and a silicone coating thereupon of 0.6 to 1.0 μm. Such a release liner is replaced in the present invention by a water-soluble coating of between 3 and 7 microns, typically 4 to 5 microns, thereby providing a substantial cost advantage.

In some embodiments, the label material, comprised of a face material, an adhesive and a water-soluble coating, is converted into joined linerless labels and the water-soluble coating removed during the printing and converting process. The use of the term “printer” or “printer/converter” in what follows is taken to mean someone who either purchases label material or manufactures label material himself, prints the upper surface of the label material, converts the label material by die-cutting the material into individual labels, and finally rewinds individual labels into reels for supply to end users and rewinds the matrix from around the die-cut labels into reels for disposal as waste. The use of the term “conversion” in the present context is taken to mean the conversion of a web of label material into reels of joined labels.

In this way, a label printer who now produces linerless label materials by coating pressure sensitive adhesives on the lower surface of the face material and a release agent on the upper surface of the face material in narrow web presses or in finishing machines can use the label material according to the present invention in a linerless system and in so doing, achieve the following advantages:a. The procurement of these supplies—adhesives and release agents—and their related job by job set up is eliminated.b. The support of major manufacturers of label materials who will be able to supply label materials according to the present invention (as opposed to conventional label materials) to label printers with benefit to both themselves and printer/converters thereby securing the benefits of the invention. This co-operation offers mutual security to brand owners investing in application changes required to label their products without needing to dispose of a release liner.c. In order to practice the present invention, investment by a printer in new equipment is limited to an additional press module, or finishing unit module, within an existing press or finishing unit in which to wash off the water-soluble coating prior to matrix stripping and reel winding. Set-up times are dramatically improved as such a wash off module can be used to produce different types of label materials.d. The printer continues to apply a varnish or release coating on top of any printing as part of the label decoration. A typical varnish or release coating for such use will include proven release agents within its formulation, in order that the finished reels of joined labels may be wound without fear of blocking.

Where the water-soluble coating is removed during the printing and converting process, the upper surface of a label material may be provided with a release coating before or after printing. Where the release coating is provided before printing, for example by the supplier of the label material, it preferably comprises a printable release coating, for example varnish formulations, which complement decoration of the linerless joined labels converted from the label material and which also act as the release coating. The use of releasable gloss or matt finish varnishes or release coatings overcomes the disadvantages of repositioning a clear release liner over the printed surface of the label material which adds cost and reduces the decoration pallet. The release life (i.e. the time during which a specified release performance is maintained) of such releasable varnishes and coatings meets current industry “Just in time logistics” at only a marginal cost premium.

In summary, the printer, having received a web of label material, is able according to the present invention toprint and (unless a release coating has been provided before printing, for example by the supplier of label material), varnish the top surface of the web of label images wherein the varnish includes a release agent,die-cut the web of label images,remove at least in part the water-soluble coating prior to rewinding into reels of joined labels for supply to the end user,without requiring the use of a silicone coated release liner.

Printable release coatings have become an article of commerce and therefore it is now possible to reverse the order of release coating and printing. Inks have been developed which can be successfully cured to adhere to such printable release coatings. The present invention encourages the use of such inks by protecting the pressure sensitive adhesive with a water-soluble coating, thereby ensuring that the printable release coating on the upper surface of the label is not exposed to the pressure sensitive adhesive until the water-soluble coating has been at least in part removed. This allows the current suppliers of pressure sensitive label materials to continue to innovate since printable release coatings are only exposed to a pressure sensitive adhesive for a much shorter time. Just in time finished label supply and applications based upon new label materials, for example those according to the present invention, widen the scope for use of printable release coatings.

In one embodiment, the wash-off module removes sufficient of the water-soluble coating within the web width and frame of the printing and converting apparatus for individual label webs to be fit for subsequent application by an end user. Preferably, the wash off module provides sufficient removal of the water-soluble coating during a commercially acceptable interval to achieve sufficient activation of the adhesive prior to winding of individual label webs at low tension.

It may be that the wash-off module uses water of any temperature between 5° to 50° C., preferably 10° to 30° C., more preferably 15° to 25° C. Factors that may help to reduce the time interval required to remove at least in part the water-soluble coating within a commercially acceptable time interval may include one or more of the following:1. The speed of dissolution of water-soluble coating.Different water-soluble polymers have different dissolution characteristics. As the lack of commercial acceptance of the prior art described herein has demonstrated, the use of a water-soluble coating in place of a silicone release liner has hitherto been frustrated by an inability to remove the water-soluble coating within an acceptable time interval, especially those water-soluble coatings based substantially upon polyvinyl alcohol polymers. As an example of faster dissolution, water-soluble coatings based substantially upon water-soluble polyurethane polymers such as those disclosed in WO1999/045050 have been found to dissolve more rapidly and to provide label materials offering greater cohesion between the adhesive system and an article than water-soluble coatings based substantially upon polyvinyl alcohol polymers.2. The extent, method and orientation of the washing procedure.An advantage of carrying out this step within a printing press is that the wash off is applied to the full width of the printing and converting equipment as compared to carrying out the wash off at an end user in a narrow web individual reel of joined labels.3. The extent of agitation provided at the surface of the water-soluble coating from first application of water to the water-soluble coating to the final waste stripping and winding of individual reels of labels.4. The concentration of dissolved water-soluble polymers in the washing medium.5. The interface and/or interaction between the pressure sensitive adhesive and the water-soluble coating. Due to the time taken to dissolve the water-soluble coating in its entirety, some part of the water-soluble coating may beneficially remain in place despite exposure to water.6. The presence of a part of the water-soluble coating remaining in place has been found to provide unexpected benefits due to the adhesive system created at the interface between the pressure sensitive adhesive and the remaining water-soluble coating. Such an adhesive system may be created between the pressure sensitive adhesive and the remaining water-soluble coating with different types of pressure sensitive adhesives including therefore water based, solvent based and hot melt formulations.7. The use of water-soluble polymers which solubilise at the interface particularly with water-based pressure sensitive adhesives although this is by way of example only. The water-soluble coating may be applied to the pressure sensitive adhesive, either sequentially where the pressure sensitive adhesive may be dried prior to application of the water-soluble coating, or simultaneously where both the pressure sensitive adhesive and the water-soluble coating are applied using a wet-on-wet dual coating process, by means of a direct coating process or a transfer coating process.8. Where both pressure sensitive adhesive and water-soluble coating are applied simultaneously by a wet-on-wet dual coating process, the two coatings are preferably formulated to be sufficiently viscous to provide solubilisation at the interface without significant further penetration of one coating into the other.9. Whether the two coatings are applied sequentially or simultaneously, the surface tensions of the two coatings are preferably adjusted so that the second coating is able to wet out completely the first coating.10. The solubilised adhesive system developed at the interface has been found to provide sufficient cohesion between the adhesive face of a joined label converted from the label material and an article to which the label is being affixed. The cohesion may be sufficient to break the weakened boundary between the label and a following label when the article is moved with respect to the label web. The cohesion and peel strength between the label and the article is enhanced as curing of the bond takes place. Curing in this context is defined as the process during which the moisture content of any remaining water-soluble coating reduces to ambient levels.

The present invention extends the opportunities to use such a water-soluble coating by recognizing the advantages of wet on wet coating to produce a pressure sensitive label material which can be printed and where necessary release coated to support the current decorative pallet and to die cut a shaped and optionally weakened label format. The die cutting advantage obtained by employing the water-soluble coating to protect the anvil together with the inclusion of a wash off apparatus within a printing and converting process or within an offline unit, extends the potential for label material manufacturers and their customers (printer/converters) to use new printable release coatings across all formats using proven quality control procedures.

In some embodiments, the label material, comprised of a face material, an adhesive and a water-soluble coating, is converted into joined linerless labels during the printing and conversion process for supply to the end user and the water-soluble coating is removed subsequently by the end user during the label application process.

In these embodiments, the water-soluble protective coating is removed at least in part by the end user immediately prior to the application of a joined label to an article by means of a label applicator. In these embodiments, the die-cutting of the joined labels by the printer/converter is again performed before removal at least in part of the water-soluble coating.

An advantage of removing the water soluble coating during the label application process is that a release coating on the face material is no longer required.

In these embodiments, the water-soluble coating is preferably capable of removal at least in part by a wash-off module within an acceptable time interval during label application.

It may be useful to provide an illustrative example of what may be considered to be an acceptable time interval.

Labelling speeds are typically in the range of 30-1000 labels per minute. The larger the label, the slower will be the running speed of the labelling line, reflecting the longer filling times required for larger containers. If a typical label width in the Home and Personal Care sector is taken as 65 mm, and a typical label application rate of 350 labels per minute, then this indicates a web consumption speed of 22.75 meters per minute. A commercially viable labelling system needs to provide sufficient removal of the water-soluble coating to reveal sufficient adhesive tack within a path length of 1.9 meters, which in turn would indicate that the water-soluble coating needs to be removed in less than 5 seconds.

It may be that the wash-off module uses water of any temperature between 5° to 50° C., preferably 10° to 30° C., more preferably 15° to 25° C. Factors that may help to reduce the time interval required to remove at least in part the water-soluble coating within a commercially acceptable time interval may include one or more of the following:1. The speed of dissolution of water-soluble coating. Different water-soluble polymers have different dissolution characteristics. As the lack of commercial acceptance of the prior art described above has demonstrated, the use of a water-soluble coating in place of a siliconised liner has hitherto been frustrated by an inability to remove the water-soluble coating within an acceptable time interval, especially those water-soluble coatings based substantially upon polyvinyl alcohol polymers. As an example of faster dissolution, water-soluble coatings based substantially upon water-soluble polyurethane polymers such as those disclosed in WO1999/045050 have been found to dissolve more rapidly and to contribute greater cohesion between the adhesive system and the article to be labelled than those based substantially upon polyvinyl alcohol polymers.2. The extent, method and orientation of the washing procedure.3. The extent of agitation provided at the surface of the water-soluble coating from first application of water to the water-soluble coating to application of the label to a container.4. The concentration of water-soluble polymers in the washing medium.5. The interface and/or interaction between the pressure sensitive adhesive and the water-soluble coating. Due to the time taken to dissolve the water-soluble coating in its entirety, some part of the water-soluble coating may beneficially remain in place despite exposure to water.6. The presence of remaining water-soluble coating has been found to provide unexpected benefits due to the adhesive system created between the pressure sensitive adhesive and the solubilised remaining water-soluble coating. The presence of a part of the water-soluble coating remaining in place has been found to provide unexpected benefits due to the adhesive system created at the interface between the pressure sensitive adhesive and the remaining water-soluble coating. Any remaining water-soluble coating may fill surface irregularities in the pressure sensitive adhesive thereby creating a smoother adhesive surface and hence greater cohesion of a partially applied label to the article being labelled. Solubilisation may be enhanced by heat applied during the drying of a web of joined labels following removal of at least part of the water-soluble coating. Such an adhesive system may be created between the pressure sensitive adhesive and the remaining water-soluble coating with different types of pressure sensitive adhesives including therefore water based, solvent based and hot melt formulations.7. The use of water-soluble polymers which solubilise at the interface particularly with water-based pressure sensitive adhesives although this is by way of example only. The water-soluble coating may be applied to the pressure sensitive adhesive, either sequentially where the pressure sensitive adhesive may be dried prior to application of the water-soluble coating, or simultaneously where both the pressure sensitive adhesive and the water-soluble coating are applied using a wet-on-wet dual coating process, by means of a direct coating process or a transfer coating process.8. Where both pressure sensitive adhesive and water-soluble coating are applied simultaneously by a wet-on-wet dual coating process, the two coatings are preferably formulated to be sufficiently viscous to provide solubilisation at the interface without significant further penetration of one coating into the other.9. Whether the two coatings are applied sequentially or simultaneously, the surface tensions of the two coatings are preferably adjusted so that the second coating is able to wet out completely the first coating.10. The solubilised adhesive system developed at the interface has been found to provide sufficient cohesion between the adhesive face of a joined label converted from the label material and an article to which the label is being affixed. Where provided, the cohesion may be sufficient to break the weakened boundary between the label and a following label when the article is moved with respect to the label web. The cohesion and peel strength between the label and the article is enhanced as curing of the bond takes place. Curing in this context is defined as the process during which the moisture content of any remaining water-soluble coating reduces to ambient levels.

According to another aspect, the present invention provides a wash off apparatus to at least partially remove a water-soluble protective coating from a web of label material thereby exposing an adhesive, the apparatus consisting of a series of assemblies including:a) A coating removal means in which water is applied to the protective coating by washing and/or wiping means, thereby at least partially removing the exposed protective coating wherein the web travels a required distance during a pre-determined time interval with such water flow, water temperature, and level of agitation as may be necessary to at least partially remove the water-soluble coating and sufficiently expose the pressure sensitive adhesive that the label is fit for purpose.b) A collection means to collect the wash water containing removed water-soluble coating, replacing a part of the wash water with fresh water when required.c) A means, for example air flow, to remove any excess water remaining upon the face material and the pressure-sensitive adhesive.d) A means, for example air dryer, to dry the web at temperatures which compromise neither the printed side nor the adhesive side of the label web.e) Optionally, a rewinding means capable of reeling the converted webs of joined labels under variable tension control.

In another aspect, the present invention provides a self-adhesive label material and a web of joined self-adhesive labels derived therefrom, wherein the adhesive is protected by a water-soluble coating providing a cushion between an anvil and die-cutting means during die-cutting of a web into individual webs of joined labels.

In a first embodiment, the protective water-soluble coating is at least partially removed from the label material after die-cutting during the process of manufacturing individual webs of joined labels.

In a second embodiment, the protective water-soluble coating is at least partially removed after die-cutting from a web of joined labels in a labelling apparatus.

In both embodiments, contrary to the teaching of Patel in aforementioned WO2007/015624 and US2012/061014, the present invention teaches that die-cutting takes place before the water-soluble coating has been removed and that die-cutting is made from a face material side of the label material using the water-soluble coating to protect the face of an anvil against which die-cutting can be provided thereby avoiding any risk of damage to the surface of the anvil beneath the label material.

