LINERLESS LABELS

Abstract

A linerless thermal sheet arranged as a roll, includes a substrate having a first face and a second face, whereby the first face opposes the second face; an adhesive layer on at least part of the first face of the substrate; a thermosensitive layer on at least part of the second face of the substrate, the thermosensitive layer including a first portion and a second portion whereby the first portion and the second portion do not overlap; a release coating applied onto the thermosensitive layer, the release coating has a low adherence to the adhesive layer; at least one colour image is deposited on the first portion of the thermosensitive layer such that the at least one colour image is between the thermosensitive layer and the release coating, whereby the second portion of the thermosensitive paper is blank for thermally-printed information.

Claims

1. A linerless thermal sheet arranged as a roll, comprising: a substrate having a first face and a second face, whereby the first face opposes the second face; an adhesive layer on at least part of said first face of said substrate; a thermosensitive layer on at least part of said second face of said substrate, said thermosensitive layer comprising a first portion and a second portion whereby the first portion is adjacent to the second portion such that the first portion and second portion do not overlap; a release coating applied onto the thermosensitive layer, said release coating has a low adherence to said adhesive layer; at least one colour image is deposited on the first portion of the thermosensitive layer so as to provide a blank window for thermally printed information in the second portion of the thermosensitive layer, whereby the at least one colour image is between the thermosensitive layer and the release coating.

2. The linerless thermal sheet of claim 1, wherein the blank window is for accommodating a barcode or a QR code.

3. The linerless thermal sheet of claim 1, further comprising a machine-readable demarcation indicating a tear/cut line.

4. The linerless thermal sheet of claim 1, wherein the at least one colour image is deposited by inkjet printing, offset printing, pad printing or roller printing.

5. The linerless thermal sheet of claim 1, wherein the at least one colour image is deposited on at least one margin of the thermosensitive layer.

6. The linerless thermal sheet of claim 1, wherein the thermosensitive layer is a colour-forming system.

7. The lineless thermal sheet of claim 6, wherein the colour-forming system is a leuco dye system.

8. The linerless thermal sheet of claim 1, wherein the machine-readable demarcation is any one of a cut-out notch, a perforation, the at least one colour image mark and/or the thermally-printed information.

9. The linerless thermal sheet of claim 1, wherein the thermally-printed information is at least one of a machine-readable representation of data, barcode, QR code, Unicode character(s), demarcation indicator(s) and/or image(s).

10. A method of manufacturing a linerless thermal sheet arranged as a roll comprising the steps: (i) depositing a colour image to a first portion of a thermosensitive layer on a first face of a substrate that is arranged to provide a blank second portion of the thermosensitive layer on the first face; (iii) apply a release coating on the thermosensitive layer on the first face of the substrate so as to sandwich the colour image between the thermosensitive layer and said release coating; and (iv) applying an adhesive to a second face of the substrate, whereby the second face of the substrate opposes the first face of the substrate.

11. The method of claim 10, further comprising the step of providing at least one machine-readable demarcation to indicate a cut/tear line, said machine-readable demarcation being at least one of a cut-out, rear-printed black marks.

12. The method of claim 10, further comprising the step of applying thermally-printed information on the blank second portion of the thermosensitive layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further preferred features and aspects of the present invention will be apparent from the claims and the following illustrative description made with reference to the accompanying drawings in which:

[0019] FIG. 1 is a schematic representation of a cross section of the linerless thermal sheet showing the various layers;

[0020] FIG. 2 is a schematic representation of a plan view of the linerless thermal sheet, with thermally printed information thereon;

[0021] FIG. 3 is a schematic representation of a roll of the linerless thermal sheet showing the arrangement of the colour images along the margins and the demarcation lines;

[0022] FIG. 4 is a schematic representation of an exemplary apparatus for manufacturing the linerless thermal roll according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0023] According to the present invention, and as illustrated in FIG. 1, a linerless thermal sheet 1 comprises a substrate 10 (shown as a thick horizontal line through the label) with a first and second side (whereby/wherein the first and second side are on opposing faces of the substrate), an adhesive layer 20 on the first side, a thermosensitive layer 30 on the second side, a coating 50 applied onto the thermosensitive layer, wherein the coating comprises a release coating that does not adhere (or has low adherence) to the adhesive layer 20 such that if the label is arranged in a stack or in a roll 70 (see FIG. 3), each sheet 1 can be removed from the stack or roll with minimal effect on adhesive layer's 20 ability to subsequently adhere to a surface other than the coating 50. The substrate 10 can be any suitable paper or plastic known in the art and the thermosensitive layer 30 can be any suitable conventional thermal or thermal transfer material known in the art. The adhesive layer 20 is a pressure sensitive adhesive (PSA). The PSA can be any conventional PSA known in the art and can be either a permanent PSA or a repositionable PSA. The release coating may be any type of release coating known in the art that has between zero to low-adherence to the adhesive layer 20. In some options, the release coating comprises silicone and can be a UV curable silicone. Typically, a barrier layer is applied to the thermosensitive layer prior to application of the release coating in order to prevent material composed of the release layer soaking into the thermosensitive layer and/or the substrate paper. In the embodiment shown in FIG. 1, the coating 50 comprising the release coating is shown as a single coating 50 that is applied directly onto the thermosensitive layer. The single coating 50 can be based on the release coating taught in the EP 0579430 (Moore Business Forms, Inc). However, the linerless thermal sheet of the present invention is not only restricted to having a single release coating 50 deposited on the thermosensitive layer but can also include a separate barrier layer.

[0024] The linerless thermal label 1 further comprises at least one colour image 40 sandwiched or disposed between the thermosensitive layer 30 and the coating 50 such that information and/or symbol(s) can be made visible on the linerless thermal sheet 1 without the need for thermal printing.

[0025] Now referring to FIG. 2, the at least one colour image is deposited on a first portion 41 of the thermosensitive layer such that a second portion 42 of the thermosensitive layer 30 is “blank” for thermally-printable information, such as that shown in FIG. 2, to be applied thereon. Either one or both of the first or second portion may comprise one or more distinct area(s) on the thermosensitive layer. In the particular embodiment shown in FIG. 2, the at least one colour image is deposited on at least one margin of the thermosensitive layer. For example, as shown in FIG. 2, the colour image is deposited on both left and right margins of the thermosensitive layer 30 such that the first portion 41 comprises two distinct areas (printed as a green banner 41a and a blue banner 41b) separated by a blank portion representing the second portion 42 therebetween (shown with a white background). The blank portion 42 provides an area for thermally printing information, e.g. text, e.g. pricing information and machine readable codes such as QR or barcodes. For example, when formed as a roll 70 as shown in FIG. 3, the colour images extend in a repetitive pattern along both the left 41a and the right 41b margins of the linerless thermal sheet. When fed through a thermal printer, information about a product such as pricing information and a machine readable code (e.g. barcode or QR code) is thermally printed in the blank regions between the colour margins as shown in the example of a printed label shown in FIG. 2.

[0026] The linerless thermal sheet may further comprise a machine-readable demarcation 60 to separate the linerless sheet into individual discrete labels. The machine readable demarcation 60 is capable of indicating the start and/or end of an individual label 2. The machine-readable demarcation 60 may be used by a printer or a label cutter to precisely cut the label to a predetermined size (depending on the position of the demarcation(s)).

[0027] The thermosensitive layer 30 may comprise any suitable colour forming system, such as a leuco dye or a metallic dye system. Optionally, or additionally, the thermosensitive layer may comprise optical brighteners. Optical brighteners (which also encompasses optical brightening agents, fluorescent brightening agents, and/or fluorescent whitening agents) are materials that absorb UV light and re-emit blue light by fluorescence. These materials, in the thermosensitive layer, cause a “whitening effect” which increases the contrast between the background and the thermally-printed information (which is typically black or dark).

[0028] The coating 50, which acts as a barrier between the thermosensitive layer 30 and the adhesive layer 20 (described below) when the thermal sheet 1 is formed as a roll, may be applied as a complete coating so as to completely cover the surface of the thermosensitive layer, or in a spot/patterned configuration. The coating 50 may be configured to lie in proximity to the adhesive layer 20 when the linerless thermal sheet is configured as a wound roll, so as to facilitate unrolling of the linerless thermal sheet without the adhesive bonding the first side of the substrate 10 to the second side of the substrate 10.

[0029] The adhesive layer 20 on the first side of the substrate 10 may be a full covering or arranged as a spotted/patterned covering. The adhesive layer 20 may be deposited onto the first side of the substrate 10 by any conventional method.

[0030] The at least one colour image 40 on a first portion 41 of the thermosensitive layer 30 may be deposited using any known methods of ink printing. The at least one colour image 40 may be in the form of a banner or banners, i.e. vertical stripe(s) as shown in FIG. 2. The at least one colour image is contrasted with a second portion 42 formed as the blank for being activated by feeding the linerless thermal sheet 1 through a thermal (e.g. direct thermal) printer. It is the juxtaposition of the at least one colour image on the first portion 41 and the blank on the second portion 42 that provides sufficient contrast between the two portions so as to clearly differentiate between them, and so as to provide a window for thermally-printed information on the “blank” second portion 42.

[0031] In some options, the at least one colour image 40 on a first portion 41 of the thermosensitive layer 30 may form a frame around blank second portion 42.

[0032] The separation of the first portion 41 and second portion 42 are so because overlaying thermally printed information over a first portion risks a lack of contrast between the thermally printed information and the at least one colour image 40, therefore making it difficult for the human eye or machine to detect the thermally printed information. For example, a machine-readable code, such as a barcode, requires sufficient contrast between the bars and the background. If the barcode is thermally printed onto the first portion 41, and the at least one colour image comprises at least one colour that is the same or similar shade to the thermally printed barcode, then the barcode may not be machine-readable or at least not effectively machine readable, leading to an unusable label. Therefore, the thermally printed information is only printed on the second portion 42 which does not overlap with the first portion 41, and remains blank such that the thermally printed information has sufficiently high contrast and can be read with ease by a human eye and by a sensor.

[0033] The linerless thermal sheet 1, which comprises the substrate 10, the thermosensitive layer 30, the adhesive layer 20, the release coating 50, the at least one colour image 40 on a first portion of the thermosensitive layer 30, and the blank of the second portion 42 of the thermosensitive layer, may be rolled to form a roll as shown in FIG. 3 having demarcations representing separate discrete labels 2 with the adhesive layer 20 in contact with the coating 50.

[0034] Typically, a thermal printer (e.g. direct thermal printer) used for activating the linerless thermal sheet 1 comprises a cutter to cut the sheet at a location based on a provided signal by a sensor, whereby the sensor is for sensing at least one of presence, absence or demarcations.

[0035] In the cases where the roll comprises separated labels, each with a fixed and predetermined length in said roll, the linerless thermal sheet 1 may comprise demarcations in the form of cut-outs. These cut-outs can be in the form of semi-circles or rectangular cut-outs along either or both of the long edges of the thermal sheet 1.

[0036] FIG. 4 shows a schematic view illustrating an exemplary process in the production of the linerless thermal roll of the present invention. In the production of the linerless thermal roll of the present invention, a web or substrate 10 coated with the thermosensitive layer 30 is fed through the production process in the direction of the arrow A to conventional coaters 80, 84 and a printer 82. The conventional coaters 80 and 84 are oriented in such a way that the adhesive coater 80 faces the web surface (first face) and the release material coater 84 faces the thermosensitive layer 30 (second face). The adhesive coater 80 applies a pressure sensitive adhesive (PSA) layer 20 on one side of the web or substrate 10. The PSA can be applied as a holt melt which coats one face of the substrate. To other side or face of the web or substrate 10 comprising the thermosensitive layer 30 is located a coater 84 for coating the thermosensitive layer 30 with a release material 50. Upstream of the release material coater 84 is a printer 82 for depositing at least one colour image 40 on the thermosensitive layer 30 prior to depositing the release layer. In order to print the at least one colour image 40 to the first portion of the thermosensitive layer 30, any known printing technique may be used. This includes inkjet printing, pad printing etc. Typically, if the at least one colour image 40 comprises a small number of colours, e.g. five or less, then standard ink printing will be used whereby each colour is applied separately. In the case where the at least one colour image comprises a large number of colours, e.g. six or greater, then digital printing techniques may be employed.

[0037] Subsequent to printing the colour image 40, a coater 84 applies a coating 50 comprising release material 50 directly onto the thermosensitive layer 30 comprising the printed colour image 40 such that the colour image 40 is sandwiched between the thermosensitive layer 30 and the release coating 50. For example, the release coating can be based on the coating taught in the art, EP 0579430 (Moore Business Forms, Inc), e.g. comprising QUILON C from Dupont Chemical Company. Optionally, as shown in dashed lines, a barrier coater 83 can be additionally applied to the thermosensitive layer 30 prior to the application of the release coating to prevent the release material 50 from soaking into the web material. The laminated web 10 is fed into a dryer 86 whereupon the coating materials, in particular the adhesive are dried onto the substrate 10. The dryer 86 can comprises a UV source for curing the silicone release coating on the thermosensitive layer 30. After the drying stage, the laminated web is fed into a cutter 88 whereupon the laminated web is cut into individual rolls 70 of linerless thermal sheets. Optionally, the cutter 88 can also apply the machine readable demarcations 60 across the laminated web in a direction perpendicular to the movement of the web so as to provide a separation of the linerless thermal sheets into individual linerless labels. The apparatus shown in FIG. 4 is for illustration only and alternative embodiments are permissible in the present invention depending on the type of adhesive and/or release coating material used. For example, the dryer can be replaced by a UV source where the release coating is a UV curable silicone material. Equally, hot melt adhesives do not require drying equipment.