WO2007110254A1

WO2007110254A1 - Rfid tag application method and adapted tag

Info

Publication number: WO2007110254A1
Application number: PCT/EP2007/050724
Authority: WO
Inventors: Marcos Serrano Timonet; Francisco Lopez Rivero
Original assignee: Compagnie IBM France SAS; International Business Machines Corp
Current assignee: Compagnie IBM France SAS; International Business Machines Corp
Priority date: 2006-03-29
Filing date: 2007-01-25
Publication date: 2007-10-04
Anticipated expiration: 2008-09-29

Abstract

An RFID tag structure suitable for the tracing of articles that are not well adapted for compatibility with conventional RFID systems such as metallic is disclosed, as is a production process for the industrialization and disposal of such a tag The RFID tag structure comprises an adhesive layer, a protective layer, an RFID chip operative at a predetermined radio frequency, situated between said adhesive layer and said protective layer, a spacer layer situated between said adhesive layer and said RFID Chip. The laminate construct characterized in that the spacer layer exceeds 2 mm in thickness and exhibits an A scale shore hardness of less than 50. The laminate structure according to the invention is especially adapted to manufacture in a continuous web, and in such a form offers further advantages in terms of the ease which RFID tags can be automatically dispensed.

Description

RFID TAG APPLICATION METHOD AND ADAPTED TAG

Field of invention

Radio Frequency identification (RFID) is an emerging technology that permits identification by means of radio waves. The identification signal is transmitted from antennae to the RFID tag. The RFID tag receives through the radio waves enough energy to activate the tags and to emit an answer from the tags.

Background art

RFID Tag technology is not mature, and research continues both at the theoretical (e.g., antenna design) and manufacturing (e.g., materials used, processing techniques) levels, to build tags of different kinds. There are many different objects that are suitable to be identified by an attached RFID tag and there are many materials and object forms to be taken in consideration. Certain fields presently lack satisfactory tag designs.

RFID tags can be classified according to the source of their operating power. Specifically, they may be classified as active, passive or semi-passive. An active tag is usually designed to perform a specific task. It has an on-board power source such as a battery. The active tags may be designed with a variety of specialized electronics including microprocessors, different types of sensors or I/O devices. Depending on the target function of the tag, this information can be processed and stored for immediate or later retrieval by a reader. Active tags in general have an effective reading distance in excess of 30 m. Another type of active tag is referred to as a transponder. This type enters into a sleep mode to conserve resources. The sleep mode is triggered by the lack of interrogation from a reader. The tag is then awakened from the low power state when the reader broadcasts a specific command. Other benefits of this type of tag are that they only broadcast if interrogated by the reader. This reduces the overall RF noise in the environment and conserves the battery life of the tag.

Semi-Active tags or battery-assisted tags differ from active tags in several ways. A battery is provided, but used for providing energy for the tag's operation or functions, and not transmission to the reader. These tags utilize the inductive characteristics of a passive tag to generate voltage and transmit the data to the reader. Since the tags are power assisted by battery, they are capable of reacting faster than a standard passive tag. Another advantage of the battery-assisted approach is in the presence of materials which may inhibit the passive type tags from functioning properly. This would result in data transmission errors since that tag would not have sufficient power to operate correctly. Semi-Active tags may be read up to approximately 30 m and at a high data rate .

Passive tags have no moving parts and in particular, no internal power source. This type of tag is very well suited for adverse conditions such as temperature extremes and chemical or corrosive environmental conditions. These tags are typically smaller, less expensive and typically have a useful read range of up to 10 meters. The tag utilizes the alternating electromagnetic field created by the reader antenna coil. It generates a voltage by induction when the electromagnetic field penetrates the cross section of the transponder's antenna coil. This voltage is rectified and acts as the power supply for energizing of the microchip and memory in the tag.

Data may be transmitted by a variety of mechanisms such as inductive coupling leading to load modulation whereby a variable degree of the energy transmitted by the remote sensor is absorbed, or backscatter coupling, whereby the amount of energy reflected back to the sensor is modulated. These and other techniques will be familiar to the skilled person.

Fig 1 shows a conventional passive RFID device 1. The base or substrate layer 13 of the tag is usually a thin plastic film. The antenna 11 and chip 12 are then sandwiched between the substrate 13 and the paper cover 14.

The largest area of growth for RFID technology is supply chain inventory tracking. Manufacturers have the potential to track inventory from the point the item was produced to when it was consumed. This differs significantly from the Universal Product Code (UPC) barcode, which has been utilized industry-wide as a product identifier. The product (s) maybe tracked throughout the supply chain, which provides advantages for inventory control (just in time), or identifying the location of the unique product that may have an expiration date or needs to be recalled.

The characteristics of RFID technology may be compared with barcode systems, for which they are often considered as an alternative. A barcode is a series of machine readable lines of varying widths. When translated, it represents a series of alphanumeric characters. Barcodes are a static representation of a specific product number or Universal Product Code (UPC) . This code, when scanned or input into a collection point, is transmitted to a delivery system. The delivery system depending on the application will translate and provide the appropriate response for that product. Barcodes have several limitations in comparison to RFID Tags: The information on a barcode cannot be dynamically changed and must be read as a individual unit. The barcode label does not contain product information. Encoded in the bar code are alphanumeric numbers that correspond to a specific product. It requires an external delivery system to maintain and utilize this information. Barcode labels are inexpensive to generate but the trade-off is the limitation of actual data being maintained at the product level. The label does not lend itself easily to automated tracking and requires an interface to back-end systems.

RFID typically utilizes the frequency between 30 Hz and 5.8 GHz. Radio frequency ranges are conventionally broken down into categories. Each category provides unique qualities and may be utilized in a variety of ways. The waves generated at these different frequencies have the ability to pass through many types of materials but exhibit different characteristics or results.

Figure 2 depicts a simplified RFID system. This system is composed of two main components. A transceiver 23 (reader or write/read) with one or more attached antennae 231 and a transponder (RFID tag) 1. The integration of several additional components is preferred to exploit RFID technology. These components are a controller 24, sensors 28, annunciators 25, actuators 26, and connectivity to back-end business systems 27. The transceiver or reader is responsible for transmitting and receiving signals in a defined target environment. The originating (AC power & clock cycle) signal in the form of an electromagnetic field 22 is utilized (in a passive environment) by the transponder or RFID tag 1. The tag 1 uses the signal 22 to activate and generate a modulated wave, which is the corresponding analogue signal 21. This signal is transmitted by the RFID tag 1 which is used during the interrogation by the reader's antenna. The information that was received by the antenna is then processed by the reader 23 and converted into a digital form. This data stream is then forwarded the controller 24 for additional processing. The controller (s) 24 provide essential communication links between the reader 23 and external entities. The functionality of the controller may be embedded into the reader or act as an individual component serving one or more readers. In addition, the controller 24 provides the ability to incorporate different types of communication interfaces (RS232, RS485, 802.x, etc.). These interfaces may provide connectivity to sensors 28, annunciators 25, and actuators 26 etc. Other interfaces may establish communication to other readers, controllers, or even back-end business systems 27.

The increasing penetration of RFID technologies has meant that it is desired to affix RFID tags to articles which are not intrinsically suited to such treatment. In the first instance, articles may be electrically unsuitable.

Electrically unsuitable means that the materials and structure of the article are such as to interfere with the functions of the radio frequency parts of the device.

Figure 3 exhibits the impact of material characteristics with regard to RF. The absorption of the electromagnetic field by the medium presents additional challenges. The absorbing materials reduce the potential power available to the transponder. The degradation affects the overall performance and reliability of the tag Ia, Ib. Different types of metals can influence the distribution of the electromagnetic fields. Depending on the properties of the materials 32, 33, 34 in the target zone, different currents or eddies may result in changes in the wave or potentially blocking it altogether. Materials like aluminium packaging 33, 34, cans for example, may present specific challenges to an electromagnetic field. Design considerations should identify limitations or future expansion requirements which may result in the introduction of new requirements. Figure 3 represents how RF waves transmit through different types of materials. Special considerations should be made when selecting a RFID solution to support a delivery system. The RF waves will travel through the object with significant distortion. Absorbent materials react differently to the higher frequency ranges.

US2004201522 describes a partial solution to some of these problems

Articles may also be mechanically unsuitable. In this context, mechanical unsuitability means that the surface of the article in question to which the tag is to be affixed is three dimensionally complex or irregular or at least rounded, so that a standard tag of the kind discussed above cannot be securely affixed or can only be affixed by undesirably deforming the active parts of the tag.

A further exacerbating factor is that in view of the increasingly significant number of articles to which RFID tags are to be affixed it is desirable to apply the tags in an automated manner. It may be envisaged that it will be desirable to affix tags to millions of similar articles as part of a manufacturing or packing process.

In summary, existing RFID Systems do not generally work satisfactorily if the tagged object is made of or contains RF opaque material such as metals or certain liquids. The form and material of the surface where the tags needs to be stuck will impose further constraints on the tag despite RFlD requirements, and furthermore should be suitable for high volume production and application.. Most of the UHF tags that are available on the market that are suitable to be used with RF opaque materials, thereby satisfying the first of these criteria are injection moulded polypropylene rigid tags, which are thus inherently unsuited to the second and third criteria. Summary of the invention

The present invention concerns a RFID tag suitable for the tracing of articles that are not well adapted for compatibility with conventional RFID systems such as metallic bottles while enabling reliable reading, and a production process for the industrialization and disposal of such a tag and the way to industrialize and dispose it on the bottle.

It is desirable to provide the following capabilities: a) Long distance readings, with a circular polarized antenna-reader . b) Adaptability to be stuck on non-flat surface such as a curved or irregular surface. c) Suitability for use in a production line with a high throughput .

In order to address these and other problems, there is provided a laminate construct as defined in the appended independent claim 1, a laminate construct formed as a continuous web for automated dispensation of RFID tags as defined in the appended independent claim 1 and a method of manufacturing a self adhesive RFID patch as defined in the appended independent claim 8. Preferred embodiments are defined in the dependent claims.

The provision of a spacer layer exceeding 2 mm in thickness and exhibiting an A scale shore hardness of less than 50 ensures excellent adhesion to irregular surfaces and provides an unexpected improvement in radio performance .

The laminate structure according to the invention is especially adapted to manufacture in a continuous web, and in such a form offers further advantages in terms of the ease which RFID tags can be automatically dispensed. The flexibility and conformability afforded by this special structure means that the tag will adhere easily to the surface of a product in high through-put production lines where articles to be tagged are moved quickly past the tag deposition mechanism, where such articles are irregular or curved and where their orientation is not fixed.

While the absence of a protective layer exposes the RFID to undue risk of damage, conventional protective layers such as paper have been found to limit the ability of conventional RFID tags to conform to irregular surfaces. The provision of a protective layer having mechanical characteristic according to the present invention has been found to offer the requisite protection without prejudicing the ability of the structure to conform to irregular surfaces.

Further advantages of the present invention will become clear to the skilled person upon examination of the drawings and detailed description. It is intended that any additional advantages be incorporated herein.

Brief description of the drawings

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which like references denote similar elements, and in which:

Figure 1 shows a conventional passive RFID device 1;

Figure 2 depicts a simplified RFID system;

Figure 3 exhibits the impact of material characteristics with regard to RF;

Figure 4a shows a cross sectional view of an RFID tag according to a first embodiment; Figure 4b shows a cross sectional view of an RFID tag according to the first embodiment;

Figure 4c shows a cross sectional view of an RFID tag according to the first embodiment;

Figure 5a shows a continuous web 50 having a laminate structure as described with respect to figure 4a;

Figure 5b shows the web of figure 5a cut so as to comprise three RFID tags 4a, 4b, 4c;

Figure 5c shows the application of an RFID tag from a continuous web according to this embodiment, from which individual RFID tags 4a, 4b have been pre-cut as described above;

Figure 6 shows a flat bed die cutting process for the preparation of RFID tags; and

Figure 7 shows a method of applying RFID tags as described with respect to figure 4 to articles .

Detailed description

According to an embodiment there is provided an RFID tag suitable for use on metallic articles that is easily applied, and which addresses the electromagnetic shielding effect caused by the metallic surface.

A spacer is disposed between the RFID chip and the metallic surface. This spacer has special physical properties in order to be thin but it is able to provide enough electromagnetic separation properties so that we can achieve the reading distance needed. A polyurethane or similar layer is provided on the outer surface so that a required degree of surface flexibility is possible. This flexibility is desirable in order to make a web (roll) of tags to feed the automatic dispenser.

The tag satisfies different desiderata: -the capability to be stuck to an ogive surface, -the capability to be stuck to any metallic surface, -the capability to the dispensed automatically

These requirements make HF based solutions less attractive since the modifications necessary to make reliable use of a reader 15cm away from the bottle would make the tag dissuasively expensive.

Figure 4a shows a cross sectional view of an RFID tag according to a first embodiment.

This RFID tag has a laminate construct 4 comprising an adhesive layer 43, a protective layer 42, an RFID chip 12 operative at a predetermined radio frequency, situated between said adhesive layer 43 and said protective layer 42, a spacer layer 45 situated between said adhesive layer 43 and said RFID Chip 12.

The spacer layer is adapted to perform the function of allowing the laminate structure to conform to the surface to which it is to adhere. In order to satisfactorily take the form of irregular packaging surfaces, the spacer layer 45 preferably exhibits a shore A hardness of less than 50, and more preferably between 25 and 50. The foam still more preferably has a shore hardness of between 30 and 35.

The spacer layer is furthermore adapted to enable the RFID tag to function in a case where the packaging to which the laminate structure is affixed contains materials likely to interfere with the radio communications of the RFID tag, for example as described with reference to figure 3. In particular such a tag is suited to a case where the packaging to which the laminate structure is affixed is a metal.

The spacer layer thus preferably provides a radio shielding effect of at least 1OdB at the radio frequency at which said RFID tag is active. The spacer layer still more preferably provides a radio shielding effect of at least 2QdB at the radio frequency at which said RFID tag is active.

It has been determined that the spacer layer material should preferably provide the following features.

• Can be die cut to a variety of shapes and sizes.

• Excellent skid-resistance, high coefficient of friction.

• Excellent resistance to marring or staining.

• Long aging resiliency will not crack or harden.

• Excellent cushioning properties.

• Excellent abrasion resistance. • Vibration and shock damping.

• Easy application pressure sensitive backing.

There are a variety of mechanisms by which the spacer layer may achieve its purpose of decoupling the RFID antenna from the material of the article to which it is affixed. For example, the thickness of the spacer layer, the density of the foam, where a foam is used, by choice of material or by addition of conductive compounds or by addition of polar groups (e.g., ethoxy, sulfonyl, carboxylate, trifluoropropoxy, and the like) to the polymer backbone.

In particular, it has been determined that a degree of physical separation as achieved by using a spacer layer in a certain thickness range offers a disproportionate and unexpected improvement in the reliability of communications with the tag, as reflected by a maximum read distance. Specifically, it has been determined that the thickness of the spacer layer is preferably between 2mm and 6mm, and still more preferably between 3mm and 4mm.

Polyurethane foams have shown themselves to be particularly well suited to these purposes, since these inherently provide a degree of electromagnetic shielding.

The Protective layer 42 is selected so as not to interfere with the reception or transmission of radio signals by the RFID device 12, whilst physically protecting the RFID device from physical or electrical damage, as well as other factors such as water ingress. In particular, the protective layer is preferably less than 0.5mm thick, and is elastic in nature, so as to permit the conformity of the laminate structure to a rounded surface without exerting an undue counter tension to the adhesive force of the adhesive layer 43.

The protection layer 42 is preferably formed of a material that does not substantially increment the superficial tension. To achieve this, the protective layer is preferably less than lmm thick, and still more preferably less than 0.5mm thick, the protective layer preferably exhibits a maximum young' s modulus along all axes in the plane of the tag of less than 5GPa, more preferably of less than 2GPa and still more preferably of less than IGPa. The protective layer exhibits an elongation to fracture preferably greater that 0.1, and still more preferably greater that 0.05. Solid polyurethane has been found to be a particularly suitable material for the protective layer 42 because it provides excellent protection to the RFID device 12 without flexibility being compromised, so that a web formed from the laminate structure thus formed can be rolled.

Suitable materials may be selected by way of example from the following list. The table lists for each prospective protection layer material a measured minimum guarantied read distance in centimetres under test conditions. Accordingly, Acrylic, PVC and polyurethane are preferred materials for this layer, with Polyurethane being the most preferred material.

Material Minimum guarantied read distance

PE 76998 110

PET 7871 110

PP 76710 117

Teslin 7841 117

PET G61SB 122

Acrilato 7711 147

PVC 3692 148

PU 3812 154

The adhesive layer 43 may be selected according to the surface to which the laminate structure is to be affixed. Generally, an aggressive contact adhesive will be suitable. For general purpose adhesion to common packaging materials acrylic or rubber based adhesives may be appropriate. For particularly uneven surfaces rubber based adhesives may be particularly appropriate in view of their ability to conform to the surface given sufficient dwell time. On the other hand, acrylic adhesives are generally well suited to high surface energy materials such as metals.

The laminate structure preferably forms a continuous web integrating a plurality of RFID tags.

There may optionally be provided a liner 44 and release layer 46 thereby facilitating the stocking of the laminated structure. The laminate structure preferably forms a continuous web integrating a plurality of RFID tags, since the storage of the web as a roll is thereby facilitated. The choice of release material may depend on the characteristics of the adhesive layer. In the case where a rubber or acrylic adhesive is selected, a silicone release layer may be suitable. Otherwise, wax, Teflon or other materials will suggest themselves to the skilled person.

Bumpon resilient rollstock product code SJ-5908 produced by 3M Corporation Industrial Tape and Specialties Division, 3M Center, Building 220-7W-03, St. Paul, MN 55144-1000, USA has been found to comprise components corresponding to the liner, release, adhesive and spacer layers offering satisfactory performance.

Figure 4b shows a cross sectional view of an RFID tag according to the first embodiment, in which the backing layer 44 and the release layer 46 are partially detached from the laminate structure enclosing the RFID device 12.

The adhesive layer 43 is thereby partially exposed, so that the laminate structure might be affixed to the intended recipient article.

Figure 4c shows a cross sectional view of an RFID tag according to the first embodiment, in which the backing layer 44 and the release layer 46 are completely removed, and the remaining laminate structure is adhered to a rounded surface 47. By way of example, it may be imagined that the surface 47 represents a section of the shell of a metallic container, for which conventional RFID tags would be unsuited due both to its curvature and electromagnetic properties. It may be seen the softness of the spacer layer 45 enables the laminate structure to conform to the surface 47, thereby ensuring a firm and stable adhesion thereto. Similarly, it may be observed that the protective layer 42 has also deformed, without causing the edges of the adhesive layer 43 to peel away from the surface 47. It is also worthwhile considering that in the inner part the foam will be compressed instead of crumpling up just like paper would.

Figure 5a shows a continuous web 50 having a laminate structure as described with respect to figure 4a. This continuous web 50 additionally comprises further RFID devices 12a, 12b, 12c etc. Individual RFID tags may then be separated from the web 50 for example by manually cutting for example with scissors, or more preferably by rotary or flat bed die cutting.

Preferably, the cutting process is carried out without separating the adhesive, spacer RFID and protective layer from the release layer 46. Fig 5b shows the web of figure 5a cut so as to comprise three RFID tags 4a, 4b, 4c. It will be appreciated that the cutting process may be carried out so as to leave surplus material surrounding each tag in a continuous web as required. The continuous web thus constituted is thus ideally suited for use in an automated process for the application of RFID tags to articles .

Figure 5c shows the application of an RFID tag from a continuous web according to this embodiment, from which individual RFID tags 4a, 4b have been pre-cut as described above. Specifically, the continuous web 50 is drawn past a roller 53 under tension. The release layer 46 and associated carrier layer 44 are drawn separately from a point beyond said roller 53, such that once the web passes the roller 53 the release layer 46 and associated carrier layer 44 are pulled in a direction divergent from the path of the remaining layers, so that the release layer 46 and associated carrier layer 44 are separated from the remaining layers, thereby exposing the adhesive layer 43. The web is then drawn past a further roller 52. The movement of the web 50 is synchronized with the passage of articles to be tagged past this further roller 52. The second roller 52 is spaced away from the path of articles to be tagged by a distance slightly less than the thickness of the laminate construct, so that as the article passes the further roller 52, its surface 47 is brought into contact with the adhesive layer 43, so that the RFID tag 4a adheres to the article's surface 47. The surplus material leftover from the die cutting process is drawn up past the second roller, and the article moves away from the roller to make way for the next article to be tagged, with a tag 4a affixed to its surface. The next tag 4b is then drawn into position to be affixed to the following article and so on.

Figure 6 shows a flat bed die cutting process for the preparation of RFID tags. A continuous laminate web as shown in figure 5a is loaded onto a roller 61, and fed past a first feed roller 62, a stamping block 64 and a second feed roller 65 onto a receiving roller 66. a driving force is applied to the receiving roller 66 so as to draw the web 50 through the mechanism under tension in a controlled manner. A flat bed die cutter 63 stamps the web 50 in a reciprocating manner so as to form an RFID tag around each RFID device 12. The flatbed die cutter is adjusted to cut through all layers of the laminate apart from the release layer 46 and the carrier layer 44, so that the RFlD tags thus formed are retained on the continuous web, and can be wound onto the receiving roller 66. At the end of a batch, for example once the web available on the first reel 61 is exhausted, the web on the receiving reel 66 may be removed for storage in its wound form.

Alternative approaches will readily occur to the skilled person, whereby for example the release layer 46 and the carrier layer 44 are cut together with the other layers.

The tags may then be separated from the web, or be retained in the web by friction or rewelding of the adhesive layer. Some or all layers may be intermittently perforated so as to be readily tearable. A plurality of

RFID tags may be arranged across the width of the web.

Where an RFID tag occupies the entire width of the web, it may be sufficient simply to cut across the width of the web rather than around each RFID device.

Fig 7 shows a method of applying RFID tags as described with respect to figure 4 to articles. Specifically, according to this embodiment there is provided a production or assembly line 70 along which a plurality of similar articles 71a, 71b, 71c, 7 Id are moved in a linear manner. A web of RFID tags for example as described with respect to figure 6 is loaded onto a dispensing roller (not shown) and fed past a feed roller 73, and onto a receiving roller 72. The receiving roller 72 is driven so as to draw the web 50 through the mechanism under tension. The feed roller is relatively small in diameter, and the web turns through an angle of 90 degrees about it, so that the pre-cut RFID tags will tend to detach from the release layer at their leading edge, somewhat tangentially to the feed roller. The feed roller is positioned in proximity to the production or assembly line 70, such that as an article e.g. 71b passes by, it is brought into contact with the adhesive layer 43 of the RFID tag 4b, so that the tag picks up on the surface of the article, and is disposed thereon.

Clearly, the arrangements described with respect to figures 6 and 7 could simply be combined, so as to define a single apparatus for the manufacture and disposal of RFID Tags.

Claims

1. A laminate construct comprising;

an adhesive layer

a protective layer,

an RFID chip operative at a predetermined radio frequency, situated between said adhesive layer and said protective layer,

a spacer layer situated between said adhesive layer and said RFID Chip,

said laminate construct characterized in that :

said spacer layer exceeds 2 mm in thickness and exhibits an A scale shore hardness of less than 50.

2. A laminate construct formed as a continuous web for automated dispensation of RFID tags, said construct comprising;

an adhesive layer

a protective layer,

an plurality of RFID chips, each operative at a predetermined radio frequency, situated between said adhesive layer and said protective layer,

a spacer layer situated between said adhesive layer and said RFID Chips ,

said laminate construct characterized in that : said spacer layer exceeds 2 mm in thickness and exhibits an A scale shore hardness of less than 50.

3. A laminate construct according to claim 1 or claim 2 wherein said protective layer is less than 0.5mm thick, exhibits a young' s modulus of less than IGPa and an elongation to fracture of greater that 0.1.

4. A laminate construct according to any preceding claim wherein said frequency is in the range 300 Mhz to 1000 Mhz .

5. A laminate construct according to any preceding claims in which said spacer layer is composed of a foam.

6. A laminate construct according to claim 5 in which said spacer layer is composed of a polyurethane foam.

7. A laminate construct according to any preceding claim in which said protective layer is composed of polyurethane .

8. A method of manufacturing a self adhesive RFID patch comprising the steps of

Laminating together

a release sheet,

an adhesive sheet,

a protective sheet,

a plurality of RFID chips operative at a predetermined radio frequency, arranged in a plane and situated between said adhesive layer and said protective layer, and a spacer layer situated between said adhesive layer and said plurality of RFID Chip,

wherein said adhesive sheet is situated between said release sheet and said spacer layer; so as to form a continuous web, and

cutting around each RFID chip though all layers apart from said release sheet,

said laminate construct characterized in that :

9. The method of claim 8 wherein said protective layer is less than 0.5mm thick, exhibits a young's modulus of less than IGPa and an elongation to fracture of greater that 0.1.

10. The method of claim 9 comprising the further step of rolling said web.

11. The method of any of claims 8 to 10 comprising the further step of sequentially applying a plurality of said self adhesive RFID patches directly from said web to articles.