GB2262056A

GB2262056A - Release coated products

Info

Publication number: GB2262056A
Application number: GB9224022A
Authority: GB
Inventors: Barry Michael Jefferson; Paul Colin Latchem
Original assignee: STANDARD CHECK BOOK Co LI
Current assignee: STANDARD CHECK BOOK Co LI
Priority date: 1991-11-15
Filing date: 1992-11-16
Publication date: 1993-06-09
Anticipated expiration: 2012-11-16
Also published as: GB9224022D0; GB2262056B

Abstract

A coated product comprising an absorbent substrate coated with a sealant and a material defining a release surface, wherein on a coated region of the substrate, the sealant is sandwiched between a layer of said release surface defining material and the substrate.

Description

A COATED PRODUCT DESCRIPTION The present invention relates to a coated product and, more particularly, to a coated paper or like product.

Labels and other articles coated with pressure sensitive adhesives are generally supplied with sheets of release paper or film protecting their adhesive coated regions. The pressure sensitive adhesives employed can be capable of binding the label, or other article, to a receptive surface (such as a sheet of paper or the surface of a wooden, metal or ceramic article) in a substantially permanent fashion, or may allow the label, or other article, to be detached from and repositioned on the receptive surface. The terms "release paper" and "release film" are understood to include within their ambits sheet like materials, which define release surfaces that bind to adhesive coated surfaces in an impermanent manner and which can be separated from the adhesive with ease, without compromising the adhesive's subsequent binding properties.Typical release papers include non-absorbant papers, such as glasine, treated with a cured silicone resin material and release films include films of polymeric materials, such as polyethylene or polyvinylchloride.

Since most known release papers and films are substantially non-absorbent, or include substantially non-absorbent substrates, it is difficult to print messages or designs onto them. Also, it has heretofore proven impossible to form a release paper by coating a silicone resin onto a normal, i.e. absorbent, paper substrate because, when coated onto the substrate, the uncured resin soaks into the substrate and, thus, does not provide the required smooth release surface on curing.

Message or memorandum pads, of the type sold under the Trade Mark POST IT NOTE, comprise stacked sheets of paper, each of which carries a region of low tack, pressure sensitive adhesive arranged to bind the sheets together to form a complete pad. The top sheet and each subsequent sheet may be peeled from the remainder of such a pad and then repeatedly stuck to and removed from a receptive surface, with minimal degradation to the adhesive's binding properties. However, this type of pad can only be formed using very low strength adhesives because more powerful adhesives would permanently bind the sheets together in the pad. The sheets cannot be formed from a less absorbent material, of a type suitable for use as a release paper, since such materials cannot easily be marked with conventional writing instruments.

It has proven difficult to employ low tack or conventional pressure sensitive adhesives to bind together the component sheets of two, or multipart sets, such as those making up business forms, invoices and the like, or message pads of the type known from European Patent Application No. 0325057, because the adhesive tends to form a strong bond to the "carbonless copying" paper used. It has been determined that even low strength pressure sensitive adhesives form a sufficiently strong bond to this type of paper, for it to be difficult to separate sheets thereof, without damage being inflicted on the paper, or the adhesive layer being disrupted.

An object of the present invention is to provide a coated product which is useful in overcoming at least one of the above discussed problems inherent in the aforementioned products.

According to the present invention there is provided a coated product comprising an absorbent substrate coated with a sealant and a material defining a release surface, wherein on a coated region of the substrate, the sealant is sandwiched between a layer of said release surface defining material and the substrate.

In embodiments, the substrate is paper, card or a like material and the sealant is a conventional varnish, preferably of a type which is cured by exposure to ultraviolet light. Preferably, the material defining the release surface is a cured polymeric material and, most preferably, is a silicone resin or a release lacquer which can be cured in situ by exposure to ultraviolet light.

When the coated product of the present invention is used as a release paper, the substrate, which may be a sheet of conventional paper, can be printed prior to being coated with sealant and the material defining the release surface. Moreover, the substrate may have uncoated regions, which are not intended to contact any adhesive, and which are free to receive printed designs or messages, or inscriptions written by hand.

In a preferred embodiment, a coated product in accordance with the present invention further comprises a sheet of flexible material, which is preferably paper, having an adhesive coated region, wherein said sheet of flexible material overlies the substrate with at least a portion of the adhesive coated region in contact with the coated region of the substrate. In a preferred embodiment, the adhesive forms a non-permanent bond between the sheet of flexible material and the coated region of the substrate. The adhesive may contact non-coated areas of the substrate and, optionally, can form a substantially permanent bond between such areas of the substrate and the substantially flexible material. In such an embodiment, the adhesive need not necessarily form any bond between the coated region of the substrate and the flexible material.The flexible material may be provided with a line of weakness, located so that the portion thereof, which overlies the coated portion of the substrate, can be separated from the remainder.

An advantage of such embodiments of the invention is that the adhesive employed can have a higher strength than those heretofore employed, without prejudicing the removability of the sheet flexible material from the substrate. Such stronger adhesives may be sufficiently strong to permanently, or semi-permanently bind the sheet of flexible material to a receptive surface, after the sheet has been removed from the substrate.

In some embodiments, such as those in which the present invention comprises a multipart set or pad of stacked paper sheets, each substrate and sheet of flexible material comprises a sheet of paper having a release surface formed on a first side and adhesive coated on the reverse so that, in the assembled set or pad, at least some of the adhesive carried by each first sheet contacts a release surface of a second sheet.

In a further preferred embodiment, the substrate and sheet of flexible material both comprise sheets of paper coated for carbonless copying. In a preferred form of this embodiment, a plurality of such substrates and sheets of flexible material form a message pad of the type described in European Patent Application No.

0325057. In this embodiment and its preferred form, the sheets comprise paper of the type sold under the Trade Mark "NCR" or the Trade Mark "IDEM", both of which are well known in the art as requiring no carbon paper so that pressure applied by marking the upper sheet of a pair, forms a copy directly on the underlying sheet of that pair.Accordingly, in this preferred form the invention comprises a plurality of substrates and sheets of flexible material, wherein each said substrate and sheet of flexible material comprises a sheet of paper, each said substrate has a region carrying a release surface, each said sheet of flexible material has a region coated with adhesive and said substrates and sheets of flexible material are interleaved together in a pad or stack, with at least some of the adhesive coated on each said sheet of flexible material in contact with the release surface of an adjacent said substrate.

In a second aspect, the present invention provides a method of forming a coated product comprising coating a region of an absorbent substrate with a varnish, curing said varnish, coating the cured varnish with a polymeric resin material, and curing said resin material. Preferably, the method comprises printing and perforating CB paper, printing, sealing and desensitising CF paper, with a mixture of desensitising ink and W curable varnish, exposing said varnish to ultraviolet light to cure the same, overprinting said varnish with one or more coats of W curable release lacquer, exposing the lacquer to ultraviolet light to cure the same, forming at least one strip of adhesive on the back of the CB paper, overlying the CB paper over the CF paper, so that the strip of adhesive at least partially contacts the cured release lacquer and the coated surfaces of the papers are in contact.

Specific embodiments of the present invention will now be described with reference to the following drawings: Figure 1 is a diagrammatic cross section through a release paper, in accordance with the present invention, adhered to an adhesive label; Figure 2 is a diagrammatic cross section through three adjacent sheets of a message pad in accordance with the present invention and; Figure 3 is a diagrammatic cross section through a second form of message pad in accordance with the present invention.

The Figures are all diagrammatic, in the sense that the thickness of the various layers of materials described has been exaggerated, for the purpose of illustration.

Moreover, although the layers of material are shown as being discrete, this is also for the purpose of illustration and, in practice, some materials will penetrate into an adjacent layer.

With reference to Figure 1, the illustrated release paper comprises a sheet of paper 1 carrying a layer of ultraviolet cured varnish 2 which, in turn, carries a layer of ultraviolet cured silicone acrylate polymer 3.

An adhesive label comprising a sheet of paper 5, carrying a coating of pressure sensitive adhesive 4, is assembled together with the release paper, with the adhesive 4 contacting the cured silicone polymer layer 3 as shown in Figure 1. The bond between the adhesive 4 and the cured polymer 3 is of sufficient strength to hold the label and release paper together, while allowing the two to be separated without damage being caused to the adhesive layer 4.

The release paper is manufactured by firstly coating the paper 1 with liquid varnish, curing the varnish under ultraviolet light to provide the cured layer of varnish 2, coating the cured varnish 2 with a curable silicone acrylate polymer, mixed with a suitable catalyst, and curing the polymer under ultraviolet light to form the cured polymer layer 3. The layer of varnish 2 is sufficient to seal the surface of the sheet of paper 1 to prevent the silicone polymer from seeping into the paper 1, prior to curing.

A suitable silicone acrylate polymer is available under the designation Rhodorsil 21621 from Messrs, Rhone-Poulenc Silicones UK of Mole Business Park, Randalls Road, Leatherhead, Surrey KT22 7BA. The preferred catalyst for Rhodorsil 21621 is available from the same source under the Trade Mark NUVAPOL PI3000. Alternatively, a UV curing release lacquer, such as that available from Zeller and Gemellin under number L01267, can be used in place of the silicone acrylate polymer. A suitable UV curable varnish is that marketed by Zeller and Gemellin under number U0707.

Figure 2 shows three adjacent sheets of paper 6, 7 and 8, from a pad comprising a stack of such sheets. The remainder of the sheets in the pad, which are not shown, are arranged similarly to sheets 6-8. The upper surface, as shown in Figure 2, of each sheet 6, 7 and 8 is coated with a strip of ultraviolet cured varnish 9.

A similarly dimensioned strip of ultraviolet cured silicone acrylate polymer 10 is formed over each strip of varnish 9. The underside, as shown in Figure 2, of each of the sheets, 6, 7 and 8, carries a strip of low strength pressure sensitive adhesive 11, located in alignment with the strips of varnish and silicone polymer 9 and 10. Thus, when the sheets 6, 7 and 8 are stacked into a pad, as shown in Figure 2, the strip of adhesive 11 on sheet 8 contacts the strip of cured silicone polymer 10 on sheet 7 and the strip of adhesive 11 on sheet 7 contacts the strip of cured silicone polymer 10 on sheet 6.

As with the embodiment shown in Figure 1, the bond between the adhesive strip 11 and an adjacent strip of silicone polymer 10 is sufficient to hold the sheets, 6, 7 and 8 in place in a pad, but allows a top sheet 8 to be peeled from the adjacent sheet 7, without damage to the sheets or the adhesive strip 11. A suitable adhesive for forming the strips 11 is the emulsion based product available under the designation E959AE from SeaLock Limited of Mitchell Close, West Portway Industrial Estate, Andover, Hampshire SP10 3TJ.

The varnish and silicone strips 9 and 10 are formed in a similar way to the varnish and silicone layers 2 and 3, illustrated in Figure 1, and the silicone strip 10 is also formed from Rhodorsil 21621.

The message pad illustrated in Figure 3 is similar to that described and illustrated in European Patent Application No. 0325057 and comprises a stack of a plurality of "Two part sets".

Only the upper four sheets of paper 20-23, of those making up the pad, are shown in detail. However, the remaining sheets 24 are arranged in a similar manner.

The sheets 20-24 are comprised of carbonless copying paper, of the type sold under the Trade Mark "IDEM".

The sheets 20-23 are arranged in pairs with the upper sheets (the "first parts" in the two part sets) 20 and 22, of each pair, comprising "coated back" (CB) paper and the lower sheets (the "second parts" in the two part sets) 21 and 23, of each pair, comprising "coated fronts (CF) paper. Preferably the first parts are Idem CB 80gsm paper and the second parts are Idem CF 60 gsm paper. When a sheet of CB paper is placed on top of a supported sheet of CF paper, with their coated surfaces touching, and sufficient pressure to mark it is applied to the sheet of CB paper, with a ball pen or the like, a copy of the mark is formed directly on the coated surface of the CF sheet.

The CF coated and upwardly facing (as shown in Figure 3) surfaces of the lower sheets 21 and 23 are coated with a strip of a mixture of 75% ultraviolet cured varnish (Zellen and Gemellin U0707) and 25% Idem desensitising ink 25. A similarly dimensioned strip of ultraviolet cured release lacquer (Zeller and Gemellin L01267) 26 is formed over each strip of varnish 25. The CB coated underside (as shown in Figure 3) of each upper sheet 20 and 22 is coated with first and second parallel strips 27 and 28 of low strength ("low tack") pressure sensitive adhesive (Sealock 959AE). The first strips of low strength pressure sensitive adhesive 27 are located in alignment with the strips of varnish and silicone polymer 25 and 26, so that when the sheets 20-23 are stacked into a pad, as shown in Figure 3, the strips of adhesive 27 contact the strips of cured silicone polymer 26.The second strips of adhesive 28 are parallel to the first strips 27 and spaced a short distance therefrom. The two strips of adhesive 27 and 28 are, in fact, of the same thickness; it is only for the purpose of illustration, that strip 28 is shown as being thicker than strip 27 in Figure 3. The strips 28 join the sheets in each pair of upper 20 and 22 and lower 21 and 23 sheets directly together, i.e. sheet 20 is bound directly to sheet 21 and sheet 22 is bound directly to sheet 23.

A third strip of adhesive (Sealock 959AE) 29 is formed on the lower most side (as shown in Figure 3) of each lower sheet, 21 and 23. The third strips of adhesive 29 function to join adjacent pairs of CF and CB sheets together and, thus, join pair of sheets 20 and 21 to pair of sheets 22 and 23. A line of weakness 30 (preferably in the form of a row of perforations) is formed between the first and second strips of adhesive 27 and 28 in each of the upper sheets 20 and 22. In an alternative embodiment, the third strips of adhesive 29 are omitted and a vertical band of adhesive (Sealock E535) 31, is applied to the spine of the pad, formed by the stacked sheets 20-23.

The varnish, silicone resin and adhesives employed in this embodiment may be the same as those used in the embodiments shown in Figures 1 and 2 and may be applied using similar methods. However, in an alternative embodiment, the strips of adhesive 27 and 28, and, when present, strip 29 are formed from a higher strength pressure sensitive adhesive. In this embodiment, while the strips of adhesive 28 and 29 or 31 serve to hold the pad together, allowing the ring binding disclosed in European Patent Application No. 325057 to be dispensed with, the release surfaces defined by the strips of release lacquer 26 allow the upper sheets 20 and 22 to be removed from the pad with ease and without damaging their adhesive strips 27 or the lower sheets 21 and 23.In an alternative version of this latter embodiment, the adhesive strips 27 are of a low strength adhesive, whereas the remaining strips 28 and 29 or 31 are of a higher strength adhesive.

As disclosed in the aforementioned European Patent Application, all of the sheets in the pad may be printed and provided with perforated lines of weakness, covers etc..

The pad illustrated in Figure 3 is preferably manufactured as follows, using a Muller Martini Progress Press, together with a Hamilton Jumbo collator. Separate rolls of CB and CF paper are processed on a Muller Martini Progress Press (or on two separate machines) and then assembled into the final product on the Hamilton Jumbo collator. The product is formed as a plurality of two part sets, the first part being formed from Idem CB 80 gsm carbonless copying paper and the second part being formed from Idem CF 60 gsm carbonless copying paper. The CB paper is fed from a roll through the Muller Press, where it is printed on its face, perforated, cut, punched (if required) and, optionally, rewound back into a roll.Meanwhile, a roll of CF paper is fed through a Muller Press, where it is printed on its face, sealed and desensitised with a mixture of 25% Idem desensitising ink and 75% UV curable varnish. The CF paper is then exposed to ultraviolet light to cure the varnish, over printed with one or two coats of UV curable release lacquer, exposed to ultraviolet light to cure the lacquer, punched if appropriate and then, optionally, rewound into a roll. The CB and CF paper are then collated together on a Hamilton Jumbo collator as follows. The CB paper, which will form the first parts, is printed with a series of pairs of appropriately located strips of low tack adhesive, and dried using hot air and/or a radio frequency drier. The CF and CB papers are then brought together, with their coated surfaces in contact, cut and collated into pads. Vertical lines of glue are applied to their spines and-the adhesives are dried using hot air blowers and a radio frequency drier. The pads are then trimmed and sheeted to provide finished pads as shown in Figure 3.

Claims

CLAINS

1. A coated product comprising an absorbent substrate coated with a sealant and a material defining a release surface, wherein on a coated region of the substrate, the sealant is sandwiched between a layer of said release surface defining material and the substrate.

2. A coated product as claimed in claim 1, wherein the substrate is paper, card or a like material.

3. A coated product as claimed in claim 1 or claim 2, wherein the substrate has at least one uncoated region.

4. A coated product as claimed in any of the preceding claims, wherein the substrate carries a printed mark under the sealant.

5. A coated product as claimed in any of the preceding claims, wherein the substrate carries a printed mark in an uncoated region thereof.

6. A coated product as claimed in any of the preceding claims, further comprising a sheet of flexible material, preferably of paper, having at least one adhesive coated region, wherein said sheet of flexible material overlies the substrate with at least a portion of an adhesive coated region in contact with the coated region of the substrate.

7. A coated product as claimed in claim 6, wherein the adhesive forms a non-permanent bond between the sheet of flexible material and the coated region of the substrate.

8. A coated product as claimed in claim 6 or claim 7, wherein the adhesive is in contact with an uncoated region of the substrate to form a more or substantially permanent bond between the sheet of flexible material and the substrate.

9. A coated product as claimed in any of claims 6-8, wherein the flexible material is provided with a line of weakness, located so that the portion thereof, which overlies the coated portion of the substrate, can be separated from the remainder.

10. A coated product as claimed in any of claims 6-9, comprising a plurality of substrates and sheets of flexible material, wherein each substrate and sheet of flexible material comprises a sheet of paper, having a release surface formed on a first side and adhesive coated on the reverse, so that at least some of the adhesive carried by a first sheet contacts a release surface of a second.

11. A coated product as claimed in any of claims 6-9, comprising a plurality of substrates and sheets of flexible material, wherein each said substrate and sheet of flexible material comprises a sheet of paper, each said substrate has a region carrying a release surface, each said sheet of flexible material has a region coated with adhesive and said substrates and sheets of flexible material are interleaved together in a pad or stack, with at least some of the adhesive coated on each said sheet of flexible material in contact with the release surface of an adjacent said substrate.

12. A coated product as claimed in any of claims 6-11, wherein the substrate(s) and sheet(s) of flexible material comprise sheets of paper coated for carbonless copying, at least from the sheet of flexible material onto the substrate.

13. A coated product as claimed in any of the preceding claims, wherein the sealant is a varnish which, preferably, is ultraviolet curable.

14. A coated product as claimed in claim 13, wherein the sealant comprises a mixture of ultraviolet curable varnish and desensitising ink.

15. A coated product as claimed in any of the preceding claims, wherein the material defining the release surface is a cured silicone resin or cured release lacquer, of the type curable by exposure to ultraviolet light.

16. A coated product as claimed in any of claims 6-15, wherein the sheet of flexible material is CB paper and the substrate is CF paper.

17. A coated product as claimed in any of claims 6-16, wherein at least two adhesive regions are defined on the sheet of flexible material, at least one of said regions being in contact with a coated region of a substrate and another said region being in contact with an uncoated region of the substrate.

18. A coated product as claimed in any of claims 6-17, wherein a line of weakness in the sheet of flexible material is located in between two adjacent adhesive coated regions.

19. A coated product substantially as hereinbefore described, with reference to any of Figures 1-3.

20. A method of manufacturing a coated product, as claimed in any of claims 1-19, comprising printing and perforating CB paper, printing, sealing and desensitising CF paper, with a mixture of desensitising ink and W curable varnish, exposing said varnish to ultraviolet light to cure the same, overprinting said varnish with one or more coats of W curable release lacquer, exposing the lacquer to ultraviolet light to cure the same, forming at least one strip of adhesive on the back of the CB paper, overlying the CB paper over the CF paper, so that the strip of adhesive at least partially contacts the cured release lacquer and the coated surfaces of the papers are in contact.

21. A method of manufacturing a coated product, as claimed in claim 20, further comprising drying the adhesives, cutting the pairs of CF and CB papers and collating said pairs into a pad or pads.

22. A method of forming a coated product, substantially as hereinbefore described with reference to Figure 3.