GB1603065A - Methods of and machines for applying labels to substrates - Google Patents

Description

(54) METHODS OF AND MACHINES FOR APPLYING LABELS TO SUBSTRATES (71) We, XEROX CORPORATION of Xerox Square, Rochester, New York, United States of America, a corporation organised under the laws of the State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to methods of applying labels to substrates, and to machines utilising such methods.

Certain automatic addressing and labeling machines for addressing or labeling articles, for example envelopes, utilize a rotatable, heated transfer wheel to carry the address-bearing item, normally referred to as a label, into physical contact with the article being addressed. (Some such machines are described in British Patent No. 1,336,436 and United States Patent No.

3,894,909). In such addressing or labeling machines suitable article transport means bring the articles, one at a time, into operative position with the label transfer wheel.

In some applications, the labels themselves are physically attracted to the articles and in this type of application, the labels carry a heat activated adhesive on their underside to enable the labels to be secured to the articles. During the relatively short interval while the label is borne by the label transfer wheel from the label supply point to the point where the label is transferred to the article, the transfer wheel must heat the label sufficiently to activate the adhesive.

In effecting the aforedescribed transfer and adhesion of the label to articles, the heat input to the label supporting pad or surface of the transfer wheel, which in turn is transmitted to the label itself, is critical. If too little heat is provided, the label may not adhere to the article. On the other hand, too much heat may result in the label sticking to the heat wheel, incomplete adhesion of the label to the substrate or damage to the label.

The address or other label information carried upon the label is frequently printed upon the label with toners or inks which tackify or otherwise become activated when subjected to heat. For example, when xerographic printing techniques are used to print label information, the toners used to make the label information visible by wellknown xerographic imaging techniques often tackify when subject to the heat which activates the adhesive. This causes the label information to offset upon the surface of the heated transfer wheel and thereby cause a ghost image of the label information to appear on at least the next succeeding label.

This offset phenomenon is well-known in the xerographic art for the problems it creates.

The term "offset" as used herein has the same meaning as in the xerographic art.

This problem of offsetting is even more acute in the present context because the bare metal heated surface of the heat transfer wheel contacts the label on the information side thereof.

As used herein, the term 'heat transfer wheel' encompasses a rotatably mounted base member having at least one heated label transfer pad thereon.

From one aspect, the invention provides a method of applying labels having heat activated adhesive on one side and printed label information on the other side to a substrate by means of a heat transfer wheel in an article addressing machine comprising: (a) forming a film on the surface of a heat transfer wheel, the film being a release agent for the printed label information and comprising a polymer having functional groups thereon, the polymer being fluid at the temperature of the heat transfer wheel; (b) contacting the side of the label having printed label information thereon with the heat transfer wheel having the release agent thereon to soften the adhesive; (c) applying the adhesive side of the label to a substrate while the adhesive is softened; and (d) allowing the adhesive to cool.

From another aspect, the invention provides an article labeling device of the type having a heat transfer wheel for transferring a printed label onto an article, at least a part of the wheel having heating means for contacting and heating the label to activate adhesive on the label to enable the label to be secured to the article, in which device there is provided means for applying a release agent as defined in the preceding paragraph on at least that portion of the wheel which contacts and heats the label.

The functional groups of said polymer preferably include carboxy, hydroxy, epoxy, amino, isocyanate, thioether or mercapto and combinations thereof.

By applying the film of release agent comprising a polymer having functional groups thereon in accordance with the present invention, the problem of offsetting or printing of a "ghost" or residual image on the next successive label is substantially overcome.

Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings, wherein, Figure 1 is a side elevational view of an addressing machine incorporating a release fluid metering device for metering release fluid on to a heat transfer wheel of the machine in accordance with the present invention, the metering device being shown out - of - contact with the heat transfer wheel.

Figure 2 is a side elevational view similar to that of Figure 1, but with the metering device contacting a label transfer device on the heat transfer wheel.

Figure 3 is an enlarged side elevational view of a release fluid metering device incorporated in said machine, said device being shown in contact with the heat transfer wheel of the machine.

Figure 4 is a side elevational view of another form of release fluid metering device shown in contact with the heat transfer wheel.

Referring to Figures I and 2 of the drawings, there is shown an automatic addressing machine 5 incorporating a label transfer wheel 10 and a release fluid metering device 80. Addressing machine 5 includes a housing or cover 9, parts of which have been broken away in Figures 1 and 2 to show the construction of certain operating components therewithin. The machine 5 has an article supply magazine 12 within which articles to be labeled are stacked, the walls 13 thereof being adjustable to accommodate articles of varying sizes.

Article conveyor 14 is employed to move articles discharged in seriatime from magazine 12, under gate 15 and pinch roller 16, past label transfer wheel 10 where the labels are transferred to the articles. The article conveyor 14 comprises one or more endless belts 17, supported by drive and idler rollers 18 and 19 respectively. Roller 18 is driven by suitable motor means (not shown) in the direction shown by the solid line arrow in Figures 1 and 2.

Labels are supplied to head 22 of addressing machine 5 from a suitable source, normally in the form of an uncut sheet (not shown) having multiple label rows. Labeling head 22 includes suitable means (not shown) to advance the label sheet forward as required to a guillotine type knife 23 which serves to cut the label supply sheet transversely into strips of several labels each. The strips rest in a downwardly inclined chute-like member 24 and are advanced therealong in the direction of transfer wheel 10 by intermittently driven pinch roll pair 25 to knife and anvil pair 26.

Knife and anvil pair 26 cooperate to cut the strip into individual labels which are discharged therefrom onto surface 86 of pad or land 30 of transfer wheel 10 as land 30 comes opposite the knife and anvil pair 26 during rotation of wheel 10. From there, wheel 10, which rotates in the direction shown by the solid line arrow of Figures 1 and 2, carries the label into physical contact with the articles being labeled as the articles move therebelow on conveyor 14. It is understood that the several label supply components of labeling head 22 aforedescribed are operated in timed relationship with one another and with transfer wheel 10 and article transport 14 to assure the requisite supply of labels to transfer wheel 10 as required.

To assure the requisite pressure contact between the labels on surface 86 of pad or land 30 of transfer wheel 10 with the articles on transport 14, there is provided opposite transfer wheel 10, a support roller 28 for transport belt 17. Roller 28 is rotated in the direction shown by the solid line arrow in Figures 1 and 2 from the addressing machine motor (not shown). Although it is not always necessary, vacuum is used in the embodiments of Figures 1 and 2 to provide vacuum to land 30 for progressively drawing the labels into vacuum attachment with surface 86 of pad or land 30. Numeral 75 represents several vacuum lines used in the preferred embodiment illustrated.The surface of the land, pad or heat transfer wheel which contacts and heats the adhesive on the label may be fabricated from any suitable material including aluminum, anodized aluminum, steel, nickel, copper, beryllium, silver or gold and alloys of the foregoing.

During the interval while the label is carried on transfer wheel 10, heat from label transfer wheel 10 is relied upon to partially melt, soften or tackify the heat activated adhesive on the bottom or back of the label.

It is during this interval that the printed matter partially melts, softens or tackifies, depending upon the type of ink, developer or toner used to print information upon the label. For example, xerographic toners well known in the art tend to tackify during this interval and partially adhere or stick to the surface of the heat transfer wheel causing "offset". This offset image prints out on subsequent labels unless steps are taken to prevent it. An appropriate release fluid is metered upon the surface of the label tranfer pad or land 30 of the heat transfer wheel 10, and this substantially reduces (and desirably prevents) offset. This release fluid is applied to the said surface as that surface moves past and in contact with a fluid metering roll 80.

The release fluid acts to prevent the sticky or softened print information on the label from adhering to the said surface of the label transfer pad.

Although print wheel 10 having pad or land 30 thereon is illustrated in Figures 1 and 2, and only the pad or land 30 contacts release fluid metering roll 80 (as shown in Figure 2) when it is adjacent thereto during rotation, the present invention encompasses other common and well known heat transfer wheels including those having no prominent land, for example, a perfectly cylindrical wheel. As illustrated in Figure 1, metering roll 80 comprises a shaft 84 adapted for rotation and an outer layer of release fluid impregnated polymer such as silicone rubber covering the shaft. In Figure 1 the surface 86 of pad or land 30 is out - of contact with metering roll 80. However, as heat transfer wheel 10 rotates and pad 30 engages metering roll 80 which is adapted for rotation about shaft 84, as illustrated in Figure 2, metering roll 80 rotates from frictional engagement with pad 30.This meters release fluid impregnated in layer 82 of metering roll 80 upon surface 86 and deposits a film of release fluid upon surface 86 preparing surface 86 for receiving another label from labeling head 22.

Metering device 80 must be positioned relative to the heat transfer wheel between the point where the label is deposited upon the article to be labeled and the point where a new label is supplied to the heat transfer wheel. Although rolls are illustrated in the drawings, other metering devices may be used in metering release fluid upon the heat transfer wheel including the pad or land.

These include release fluid impregnated or carrying brushes, pads, wicks or belts, atomizer sprays or doctored rollers carrying release fluid from a sump. Figure 3 is exemplary of the release fluid impregnated roller where numeral 82 represents a silicone rubber impregnated with a release fluid. Figure 4 is exemplary of a doctored roller 89 mounted upon core 87, for example a silicone rubber roller upon a steel shaft, adapted for rotation relative to heat transfer wheel 10. Doctor blade 88 removes excess release fluid from roll 89. A supply of release fluid 85 is maintained in sump 81 and as roll 89 rotates in release fluid 85, release fluid is carried by roll 89 where the excess fluid is removed by doctor blade 88 and release fluid is transferred from roll 89 to surface 86 of heat transfer wheel 10. A wicking assembly is shown in U.S. Patent No. 3,884,181 and U.S. Patent No.

3,799,401. Typical offset preventing fluid supply rolls and belts are disclosed in U.S.

Patent No. 4,056,706.

Metering devices may be continuously maintained in contact with the surface of the heat transfer wheel or there may be intermittent contact. Suitable camming devices (not shown) may be used to provide the intermittent contact. When the release fluid metering device is a roll adapted for rotation, the roll may be activated (rotate) due to frictional contact with the heat transfer roll as in Figure 2, or it may be driven by a motor (not shown) or by the power drive of the labeling device.

The heat transfer wheels generally have bare metal surfaces which contact the labels bearing printed information. The softened or tackified print information has an increased tendency to stick to the bare metal. In accordance with the present invention only certain classes of release fluids applied to the bare metal surfaces reduce or eliminate the tendency of the softened or tackified print information to adhere to the bare metal surfaces. These are polymeric materials having functional groups thereon. The functional groups are generally carboxy, hydroxy, epoxy, amino, isocyanate, thioether, mercapto and combinations thereof. Common release agents such as mineral oil and silicone oil (polydimethyl siloxane) do not reduce or eliminate the offset problem and do not prevent the printed information from sticking or adhering to the bare metal surface of the heat transfer wheel.

In certain embodiments (not shown) the heat transfer wheel can also be used to fix or fuse the printed information to the label substrate, for example, when the printed information is xerographic toner deposited upon the label. The release fluid or agent prevents the toner from adhering or sticking to the surface of the heat transfer wheel as described above. In this embodiment, the heat transfer wheel serves as a heated surface to fix or fuse the print information on one side of the label substrate and to soften or tackify the adhesive material on the other side of the label substrate.

The polymeric fluid, which has a suitable release function for the printed information on the label when the ink or toner is softened, forms an interfacial barrier between the metal or other material of the surface of the heat transfer wheel and the outer layer of the same fluid release material. In accordance with the present invention, this characteristic is found in polymeric fluids which contain, for example, such chemically reactive functional groups as carboxy, hydroxy, epoxy, amino, isocyanate, thioether or mercapto and combinations thereof. These fluids are described in British Patent Application No. 19868/75 (Serial No.

1507496).

The present invention encompasses polymeric fluids which are characterized by the above-described properties and which have the necessary functionality. By use of the term "functionality", is meant any material- -which is characterized by chemically reactive functional groups such as , for example, carboxy, hydroxy, epoxy, amino, isocyanate, thioether or mercapto, which interact with the surface of the heat transfer wheel. Such compounds or materials having the functionality are generally organic, but in certain cases compounds generally designated as inorganic materials may also be included in the class of materials which are operable in accordance with the teachings of the present invention.Organosiloxane polymers, generally designated as inorganic polymers because of siloxane backbone structure comprising alternate silicon and oxygen atoms in the backbone, belong to that class of polymeric fluids which are operable in accordance with the present invention, as long as they contain the chemically reactive functional groups capable of interacting with the fuser member surface to form a thermally stable interfacial barrier. The backbone poly siloxane chain itself (siOSi )n is inorganic in nature, and because of this polysiloxane chain it is characteristically thermally and chemically stable. However, it may also be considered organic in nature because of the hydrocarbon content of the polymers.

The organic substituted polysiloxane derivatives, for example, the alkylsubstituted polyorganosiloxanes, having the appropriate chemically reactive functionality have been found particularly useful in accordance with the present invention.

A typical polysiloxane is of the dialkyl type having the general formula:

wherein R represents a "spacer" group pendant from the polymer backbone and X represents a functional group. ln preferred embodiments R is an alkyl moiety having 1--8 carbon atoms, typically a propyl group (-CII2-CHrnCH2-).

For a typical polymer having a one mole percent functional content, there is 1 a moiety for every 99 b's. If the functional group content is 2 mole percent, there is an average of 2 a moieties for every 98 b moieties. In a preferred embodiment, where a is an integer from 1 to 3, b may be an integer from 50 to 600.

The R spacer groups may all be similar, for example, methyl, ethyl or propyl, or they may be mixtures of alkyl groups, for example, mixtures of propyl and butyl or ethyl and propyl. In addition, the R spacer group may be a straight chain, or it may be branched. The typical molecule shown in the general formula above comprises methyl groups substituted on the Si atoms in non-spacer group sites. However, these non-spacer group sites may typically comprise general alkyl groups from about 1 to 6 carbons and mixtures thereof Other groups may be substituted at these sites by one skilled in the art as long as the substituted groups do not interfere with the functional groups designated in the general formula by X. The -R-X groups may be randomly positioned in the molecule to provide the functional groups critical in the release agents used in the present invention.

X, which represents the critical functional groups, is typically carboxy, hydroxy, epoxy, amino, isocyanate, mercapto or thioether. Alternatively or in addition, the functional groups (X) may be located on spacer groups (R) at terminal sites on the molecule, i.e., the molecule may be "endcapped" by the functional groups.

Other fluids which have been found operable in accordance with the present invention include those polymers which are fluid at operating temperatures and which have the designated functionality. For example, polyethylene polymers having any of the above-described functional groups, polypropylene having any of the abovedescribed functional groups or polyisobutylene having any of the above-described function groups, may be used in accordance with the present invention. Other examples of organic polymers which may be used in accordance with the present invention are the vinyl polymers having functional groups, for example, polystyrene with carboxylic groups, polystyrene with amino groups, polystyrene with hydroxyl groups, and the like.Other homopolymers and copolymers may also be used, for example, copolymers of ethylene and acrylic acid, ethylene and methacrylic acid, propylene and acrylic acid, propylene and methacrylic acid, isobutylene and acrylic acid, isobutylene and methacrylic acid, ethylene and acrylamide, ethylene and methacrylamide and homopolymers and copolymers of 2 - cyanoethyl acrylate.

Other polymeric fluids having chemically reactive functional groups which may be used in accordance with the present invention, are those materials which have the above-described characteristics when metered or coated upon a heat transfer wheel surface, examples of which are functional group-substituted biphenyls and functional group-substituted polyphenyl ethers, for example, functional groups such as carboxy, hydroxy, epoxy, amino, isocyanate, thioether and mercapto.

Although concentrations of functional groups in the polymeric fluids greater than 10 mole percent may be utilized in accordance with the present invention, there generally is no advantage in utilizing concentrations higher than 10 mole percent.

Functional groups in concentrations even as low as 0.2 functional groups per molecule on average have produced suitable results.

To treat the surface of a heat transfer wheel by applying at least one polymeric fluid containing chemically reactive functional groups, one can adjust the concentration of the functionality of the polymeric fluids to provide optimum release of the softened or tackified printed label information. As used herein, "printed label information" refers to the print or toner or other visible coloring material or pigment on the surface of the label substrate. Label substrate" refers to the paper, plastic, film or other material bearing the information and is distinguished from the article substrate to which the label is adhered, applied or secured.

The modes in which the release agents are utilized are those wherein the coating or film is continuously or intermittently applied to the surface of the heat transfer wheel. The polymeric fluid having functional groups therein may be applied to the heat transfer wheel by any of the standard or conventional methods or devices, and include application by brushes, by spraying, by metering from a sump, by application from a wiper blade or wiper comprising the polymeric fluid having the functional groups therein, by applying from a suitable sump, by applying from a wick or by padding.

The polymeric release material may also be applied in the form of a solid which becomes fluid at operating temperatures, for example, a block of the polymer having suitable functional groups may rub against the heated surface of the heat transfer wheel to apply a film of the polymer on the heat transfer wheel. The polymeric release agent may also be applied in conjunction with a cutting or dilution agent with which it is miscible, that is, as two or more miscible components. An example of this embddiment is a mixture of the polydimethylsiloxane having functional mercapto groups attached to a propyl spacer group mixed with the polydimethylsiloxane (silicone oil) with which it is miscible and which acts as a dilution agent. The release agents or fluids of the present invention may also be applied as a single component to provide both the interfacial barrier and the release surface.

The fluid must be applied in an amount sufficient to cover the surface with at least a continuous low surface energy film in order to provide the heat transfer wheel with a surface which not only releases the printed label information heated by the wheel or pad thereon but also with an amount which will prevent the printed information from contacting the surface of the fuser member.

Generally, the amount sufficient to cover the surface must be that amount which will maintain a thickness of the fluid in a range of submicron to microns and is preferably from 0.5 micron to 10 microns in thickness.

The polymeric fluids having chemically reactive functional groups which are applied to the heat transfer wheel must not be curable to the extent that they form a solid or gel at operating temperatures for reasonable periods of time. The reasonable time is dependent upon the labeling volume of the device, and a reasonable period of time is at least 200 hours and may be 1,000 to 2,000 hours or longer. The operating temperatures may vary from 400 to 5000C, the preferred operating range being that providing the amount of heat necessary to soften or tackify the adhesive on the label sufficiently so that it will adhere to a substrate.

The present invention may be used on the heat transfer wheel regardless of the type of ink, toner, pigment or other colored material used to provide the printed label information. However, it is especially useful when the printed label information on the side of the label adjacent the surface of the heat transfer wheel is a heat softenable or heat-tackifiable coloring or printing material such as xerographic toner. Typical toners available for this purpose are well known in the art. For example, a copolymerized mixture of styrene or a blend of styrene monologs with 10o0 percent (by weight) of one or more methacrylate esters selected from the group consisting of ethyl, propyl, and butyl methacrylates as described in U.S. Patent No. 3,079,342 may be used.Typical toner materials include gum copal, gum sandarac, rosin, asphaltum, pilsonite, phenol formaldehyde resins, rosin-modified phenol formaldehyde resins, methacrylic resins, polystyrene resins, polypropylene resins, epoxy resins, polyethylene resins and mixtures thereof.

Among other patents describing thermoplastic electroscopic toner compositions which are used to provide printed label information are U.S. Patent No. 2,659,670 to Copley; U.S. Patent No. 2,753,308 to Landrigan; U.S. Patent No. 3,079,342 to Insalaco; U.S. Patent Reissue No. 25,136 to Carlson and British Patent No. 768,293 to Rheinfrank et al.

In the following examples, silicone rubber rolls are impregnated with fluids and inserted in a system similar to that shown in Figures 1 and 2. The fluid-impregnated roll is similar to the roll designated by numeral 80 in Figure 3. Address labels on a paper substrate are printed xerographically, and the printed label information thereon is a heat-softenable toner similar to the toner described above and designated by the trade designation Xerox 660 Toner. Xerox is a registered trademark of Xerox Corporation.

The xerographically printed labels are placed in a labeling device similar to the one shown in Figures 1 and 2. The labels have a heat-softenable adhesive backing for securing them to articles. Paper envelopes are passed under the bare metal heat transfer wheel having a copper-surfaced pad thereon, and the labels having softened adhesive backings are secured to the paper envelopes.

In tests run without a release fluid and without a release fluid metering device, there was offsetting of the printed label information (toner) upon the heat transfer wheel, and the offset image was transferred from the wheel to the next successive label.

In tests run with a metering device as shown in Figure 3 impregnated with silicone oil, there is offsetting of the printed label information (toner) upon the heat transfer wheel even though silicone oil (nonfunctional polydimethyl siloxane) is metered on the wheel and formed a film thereon. This offset image (toner) on the wheel was then transferred to the next successive label and appeared as a ghost image thereon.

In tests run with a metering device as shown in Figure 3 impregnated with a polydimethyl siloxane having mercapto groups attached to a propyl spacer group, there was no offsetting of the printed label information (toner) upon the bare metal of the heat transfer wheel. The mercaptofunctional polydimethyl siloxane had a molecular weight of 14,000, a viscosity of 275 centistokes, and a sulfur content of 0.18 sulfur groups/molecule. No "ghost" images appeared upon successive labels which contacted the heat transfer wheel.

In another example, conditions were identical expect the mercapto-functional polydimethyl siloxane was diluted by adding 3 parts by volume Xerox Fuser Oil (polydimethyl siloxane). The sulfur content of the blend was 0.04 sulfur groups or atoms per molecule and the viscosity was 160 centistokes. There was no offset of the printed label upon the bare metal surfaced heat transfer wheel.

As used herein, "offset" or "offsetting" is the transfer of printed label information (toner) from one substrate to another substrate and more specifically, from the substrate to which it is affixed as printed label information, for example, a label, to the surface of the heat transfer wheel. When printed label information (toner) contacts the heated heat transfer wheel, the toner liquifies, softens, tackifies or becomes molten, and in this state it has a tendency to split, part of the printed label information (toner) remaining on the label substrate and part of it transferring to the surface of the heat transfer wheel. This is known as "hot offset". Splitting of the printed label information (toner) occurs when the cohesive forces holding the viscous toner mass together, is less than the adhesive forces tending to offset it to a contacting surface such as heated transfer roll. Release failure occurs when there is a splitting of the image when the toner is softened and is sufficiently sticky to adhere to the surface of the heated transfer wheel which results in a partial or ghost image on the next label, producing what is referred to as an offset image.

Claims (22)

WHAT WE CLAIM IS:

1. A method of applying labels having heat activated adhesive on one side and printed label information on the other side to a substrate by means of a heat transfer wheel in an article addressing machine comprising: (a) forming a film on the surface of the heat transfer wheel, the film being a release agent for the printed label information and comprising a polymer having functional groups thereon, the polymer being fluid at the temperature of the heat transfer wheel; (b) contacting the side of the label having printed label information thereon with the heat transfer wheel having the release agent thereon to soften the adhesive; (c) applying the adhesive side of the label to a substrate while the adhesive is softened; and (d) allowing the adhesive to cool.

2. A method according to Claim 1 wherein the polymer is continuously applied on the heat transfer wheel to maintain a film of the release agent thereon.

3. A method according to Claim 1 or Claim 2 wherein the functional groups of the polymer comprise carboxy, hydroxy, epoxy, amino, isocyanate, thioether, mercapto and combinations thereof.

4. A method according to any preceding Claim wherein the polymer comprises polydialkyl siloxane having carboxy, hydroxy, epoxy, amino, isocyanage, thioether or mercapto functional groups or combinations thereof.

5. A method according to claim 4 wherein the functional groups are substituted on the alkyl moiety of the dialkyl polysiloxane.

6. A method according to any preceding Claim wherein the polymeric fluid having functional groups is blended with at least one dilution agent which is miscible therewith.

7. A method according to Claim 6 wherein the dilution agent is polydimethyl siloxane.

8. A method according any preceding Claim wherein the polymer having reactive functional groups comprises a polysiloxane having the general formula:

wherein R represents an alkyl group pendant from the silicon atom, X represents a mercapto group, a is an integer from 1 to 3 and b is an integer from 50 to 600.

9. A method according to Claim 8 wherein the alkyl group has 1 to 8 carbon atoms.

10. A method according to any preceding Claim wherein the printed label information is thermoplastic electroscopic resin deposited on the label.

11. A method according to any one of Claims 1 to 10 wherein the heat transfer wheel has a bare metal surface.

12. A method according to Claim 11 wherein the surface of the heat transfer wheel comprises copper.

13. A method according to Claim 11 wherein the surface of the heat transfer wheel comprises aluminum.

14. An article labeling device having a heat transfer wheel for transferring a printed label onto an article, at least a part of the wheel having heating means for contacting and heating the label to activate adhesive on the label to enable the label to be secured to the article, in which device there is provided means for applying a release agent as defined in any one of Claims 1 to 9 on at least that portion of the wheel which contacts and heats the label.

15. The article labeling device according to Claim 14 wherein the means for applying a release agent comprises a sump containing release fluid and means for conveying the release fluid from the sump to the wheel.

16. The article labeling device according to Claim 15 wherein the means for conveying release fluid to the wheel is a wick.

17. The article labeling device according to Claim 15 wherein the means for conveying release fluid to the wheel is a metering roll.

18. The article labeling device according to Claim 14 wherein the means for applying release agent is a roller impregnated with release fluid.

19. The article labeling device according to Claim 14 wherein the heat transfer wheel is as defined in any one of Claims 11 to 13.

20. An article labeling device substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

21. A method of applying labels having heat-activated adhesive on one side thereof and printed label information on the other side thereof to a substrate by means of a heat transfer wheel, substantially as hereinbefore described.

22. A method of applying labels having heat-activated adhesive on one side thereof and printed label information on the other side thereof to a substrate by means of a heat transfer wheel, substantially as hereinbefore described with reference to the accompanying drawings.