NZ242781A - Multi-layered printable sheet structure with self adhesive peelable label - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £42781 ) 242781 Priority Data's): . .0.'.^V,?l\ Complete Specification Fi'.sd: C!»55?: &$Xf^nW;.

Publication Dete: .... 15. .FEB. 1994....

P.O. Journal, No: C?TO Patents Form Mo. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION MDLTILAYERED PRINTABLE SHEET STRUCTURE WE, NYLEX CORPORATION LIMITED, an Australian company of 15th Floor, 390 St. Kilda Road, Melbourne, Victoria 3004, AUSTRALIA 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 statements - 1 - ff" (followed by page'^a) cO, - IQ- 242781 MULTILAYERED PRTNTABLE SHEET STRUCTURE This invention relates to a multilayered sheet structure and more particularly to a sheet structure 5 incorporating a self adhesive label and backing sheet. It will be convenient to describe the invention with reference to its application in outdoor situations and being printed upon by laser printer or photocopier. However it should be noted that the invention has a wider 10 application.

Various types of self-adhesive paper labels are known. Self-adhesive paper labels are, for example, commonly used to provide address indicia for envelopes. The address indicia may be printed on to such labels by 15 means of offset printing or other conventional printing techniques; or alternatively, the labels may be blank and receptive to typed or hand written address indicia.

It will be appreciated that the usefulness of self-adhesive labels is not confined to use on envelopes; 20 such labels are also used as "bumper stickers" or "decals". However, paper labels are not generally suitable for outdoor use because they do not have the required durability and resistance to weather, so outdoor self-adhesive labels are generally made from polymeric 25 materials.

It is generally difficult to write or print onto polymeric materials because they are generally not as receptive to ink or other forms of marking as is paper. Moreover, the inks which do print on polymeric materials 30 generally utilize hazardous solvents. Thus labels suitable for outdoor use are normally pre-printed and do not allow a user to insert information of his choice, as do paper labels.

With the present widespread use of photocopiers and 35 laser printers, and with the increasing availability of colour photocopiers and colour laser printers, it has become easy and convenient for people to create their own signs, posters and other graphic materials. In~~cer.tain u -'Vi applications, the usefulness of such materials . ^jalid designs JL "(followed by p'age '2)1 - 2 242781 is enhanced if the medium on which they are printed is in the form of a self-adhesive label particularly on labels which are weatherproof.

A particular problem arises in the use of 5 self-adhesive labels in conventional laser printers and photocopiers, in that laser printers and photocopiers normally operate by fusing toner onto the paper or other print medium, so that the print medium must be able to withstand a high temperature and pressure. This presents 10 particular problems when the print medium is a self-adhesive label, in that the label, the adhesive, and the backing sheet must all be able to withstand the high temperatures and pressures.

Adhesives often break down at high temperatures, but 15 adhesives which can withstand high temperatures are known. A more important problem is the provision of a backing sheet which can withstand high temperatures. A common problem with backing sheets for self-adhesive labels is that they shrink or distort when subjected to 20 high temperatures. This results in wrinkling or curling of the label. As modern laser printers and photocopiers require that the material being printed remain flat, such deformation leads to unsatisfactory performance of the printing onto the self-adhesive labels.

Accordingly, there is a need for a self-adhesive printable label suitable for outdoor use which can withstand the temperatures and pressures encountered in modern photocopiers and laser printers without deforming during the printing process.

Accordingly, the present invention provides a multilayered printable sheet structure comprising a self-adhesive film consisting of:- (i) a vinyl base layer having a first and second surface; (ii) a printable layer bonded to said first surface, said printable layer including one or more fillers and/or pigments; and (iii) an adhesive layer on said second surfaqe^and o".\ a backing sheet consisting of:- ,.i, <?\ JL 242 ^ (iv) a paper backing layer having a first and second surface; (v) an adhesive-release agent layer on said first surface intermediate said paper backing layer and said adhesive layer; and (vi) a moisture barrier layer on said second surface of said backing layer.

The vinyl base layer may be of any suitable size, shape and thickness. The base layer must be of suitable 10 thickness to impart sufficient strength to the film so that the film does not stretch or shrink excessively once removed from the backing sheet. The base layer may be of any width and length convenient for manufacture by way of conventional polymeric film manufacturing equipment. 15 Optionally, various modifiers may be added to the vinyl base layer to impart desirable characteristics to the layer. For example various ultraviolet stabilizers, plasticizers and pigments may be added to the base layer so to provide desired properties as is well known in the 20 art.

A printable layer is bonded to one surface of the vinyl base layer. The printable layer is preferably capable of accepting toner used in conventional laser printers and photocopiers. Preferably it should also be 25 sufficiently thermally stable so as not to deform when subjected to the temperatures and pressures normally encountered in such machines. In a preferred embodiment, the printable layer comprises a vinyl based lacquer including a filler and pigments. Suitable fillers may 30 include cellulose to improve printability of the printable layer. The filler may act as a binder to bind pigment particles together and to the vinyl base layer and to assist adhesion of the printable layer to the base layer. Suitable binders include poly(vinyl alcohol), acrylic 35 based emulsions and poly(vinyl acetate) suitable pigments include titanium dioxide, magnesium oxide, calcium carbonate, kaolin clays, and silicas. Coloured pigments may be included in the printable layer. In a preferred embodiment of th e fcfes'erife'i cfcifrfrgntijon the printable layer JL 12 NOV 1993 242781 comprises 85% to 95% vinyl, 1% to 10% cellulose, 1% to 5% titanium dioxide and 1% to 5% magnesium oxide.

The adhesive layer is on the opposite side of the base layer to the printable layer. The adhesive may be 5 any suitable temperature stable adhesive known in the art. Preferably, the adhesive is a permanent acrylic adhesive.

The backing sheet consists essentially of:-(i) a backing layer; (ii) an adhesive-release agent on one side of the backing layer; and (iii) a moisture barrier layer on the opposite side of the backing layer.

The paper backing layer may be any suitable paper 15 backing known in the art. The paper layer is preferably of suitable thickness and strength such that the backing sheet can be removed from the self-adhesive film in one piece. Preferably, the weight of the paper used in the paper layer is between 80 and 170 grams per square metre, 20 most preferably between about 130 to 140 grams per square metre.

The adhesive-release agent layer is provided on the side of the paper backing layer which contacts the adhesive layer on the self-adhesive film. The 25 adhesive-release agent layer co-operates with the adhesive layer so that the backing sheet is removably bonded to the self-adhesive film during printing, but can be easily removed when the self-adhesive film is ready to be affixed to an object. Preferably, the adhesive-release agent 30 layer is a silicon based layer.

The moisture barrier layer is bonded to the paper backing layer on the opposite side to the adhesive-release agent layer. The moisture barrier layer is essential to enable the multilayered printable sheet structure to be 35 printed upon in a laser printer or photocopier without deforming. By preventing moisture loss from the sheet structure subjected to the high temperatures of the printing machine, water loss from the sheet strupture^is minimized and thus curling of the sheet structure iS^. i ? r~ JL o V; J '4% 1 7 B % jjPLj fiA fifw lj \y u thereby limited. This enables the products to remain flat which is critical during the laser printing operation. Moreover, the moisture barrier layer gives the multilayered printable sheet structure stability against 5 variations in humidity or temperature. The moisture barrier layer may be formed from any suitable moisture resistant compound such as polyvinylidene chloride, polyethylene, chlorinated vinyl-acrylate co-polymer. In a preferred embodiment, the moisture barrier layer comprises 10 a PVDC emulsion comprising water, polyvinylidene chloride and one or more surfactants, in particular one or more wetting agents. The moisture barrier emulsion comprises between 50% to 80% by weight of water, between 20% to 50% by weight of polyvinylidene chloride and between about 1% to 5% by weight of wetting agents. In a most preferred embodiment, the moisture barrier layer is applied to the paper backing layer as an emulsion which comprises about 70% water, 28% PVDC and about 2% wetting agents. A 15 suitable PVDC emulsion is Kuroform 193 D (recognized trade mark). Suitable wetting agents are Surfynol S.E. and Antarox LF222 (both recognized trade marks).

The invention will now be described in more detail with reference to the following example. It is to be 20 understood that the example and following description relate to a preferred embodiment only, and is not intended to limit the scope of the present invention.

EXAMPLE A printable layer is comprised of a vinyl based lacquer with the following additives Component Quantity (parts) /*•" \ Vinyl based lacquer 100 ^\\ Cellulose 5 *0 DEC 1993*) Titanium dioxide 2.5 ' /J itT Magnesium oxide 2.5 { The above ingredients are mixed together with speed stirring and coated onto a vinyl base layer by rotogravure coating. The printable layer is coated at a coating weight of 50 grams per square metre.

Claims (14)

f?. fy 4=^ - ' •• h - 6 - The printable layer and vinyl base layer are then heat fused together. This forms a stable synthetic substrate with a durable surface receptive to all forms of label printing. 5 A moisture barrier layer is prepared as follows:- Component Quantity (parts) Water 100 10 Kuroform 193 D (55% PVDC, 45% water) 100 Surfynol S.E. 2 Antarox LF222 1 The above ingredients are mixed gently to minimize 15 foaming. The resulting emulsion which contains the wetting agents to facilitate smoothness of coating and surface texture is applied either by gravure coating or reverse gravure coating. The emulsion is applied to the paper layer at a coating weight of 10 grams per square 20 metre (dry weight). The paper weight may be between 80 and 170 grams per square metre. Preferably, the paper weight is 130 grams per square metre. Prior to coating of the paper layer, dilution of the emulsion allows further penetration of the 25 emulsion into the paper. After coating, the structure is cured in a direct gas fired oven at 60 metres per minute web speed. The (i) vinyl base layer and printable layer and (ii) paper backing layer, adhesive release-agent layer and moisture barrier layer 30 are then laminated using a permanent acrylic adhesive using a transfer coating method known in the art to achieve the finished product. It will be appreciated that various modifications, additions and/or alterations may be made to the structure 35 previously described without departing from the ambit of the present invention. J. CW !C$ JL 12 NOV 1993 WHAT ^/WE CLAIM IS: - 7 -

1. A multilayered printable sheet structure comprising a self-adhesive film consisting of:- (i) a vinyl base layer having a first and second 5 surface; (ii) a printable layer bonded to said first surface, said printable layer including one or more fillers and/or pigments; and (iii) an adhesive layer on said second surface; and .10 ... ,a , backing sheet consisting of:- (iv) a paper backing layer having a first and second surface; (v) an adhesive-release agent layer on said first surface of said backing layer intermediate said paper 15 backing layer and said adhesive layer; and (vi) a moisture barrier layer on said second surface of said backing layer.

2. A multilayered printable sheet structure according to claim 1 wherein said printable layer includes one or 20 more fillers and/or binders selected from the group consisting of cellulose, poly(vinyl)alcohol/ acrylic-based emulsions, poly(vinyl acetate), titanium dioxide, magnesium oxide, calcium carbonate, kaolin clays and silicas. 25

3. A multilayered printable sheet structure according to claim 1 or 2 wherein the printable layer comprises between 85% to 95% vinyl, 1% to 10% cellulose, 1% to 5% titanium dioxide and 1% to 5% magnesium oxide.

4. A multilayer printable sheet structure according to 30 any one of claims 1 to 3 wherein said printable layer is coated onto said vinyl base layer at a coating weight of 50 grams per square metre.

5. A multilayered printable sheet structure according to any one of claims 1 to 4 wherein the moisture barrier 35 layer is comprised of polyvinylidene chloride, polyethylene, or chlorinated vinyl-acrylate co-polymer, or a combination thereof.

6. A multilayered printable sheet structure according to claim 5 wherein the moisturet barrier layer comprises polyvinylidene chloride and O /- ^ o L- • // ri; - 8 - wetting agent.

7. A multilayered printable sheet structure according to any one of claims 1 to 6 wherein said paper backing layer has a mass of between 80 and 170 grams per square 5 metre.

8. A multilayered printable sheet structure according to any one of claims 1 to 7 wherein said sheet structure is capable of being printed upon by xerography.

9. A method of forming a multilayered printable sheet 10 structure comprising the steps of:- (i) coating a mixture of a vinyl-based iacquer arid one or more fillers and/or pigments onto a vinyl-base layer; (ii) subjecting said vinyl-based layer and coating 15 mixture to heat to fuse said layer and mixture; (iii) coating a paper layer with a moisture barrier emulsion of polyvinylidene chloride and one or more surfactants and/or wetting agents; (iv) curing said coated paper; 20 (v) applying an adhesive to the vinyl base layer; (vi) applying an adhesive release agent to the uncoated side of the coated paper layer; and (vii) adhering said adhesive to said adhesive release agent. 25

10. A method according to claim 9 wherein said mixture of vinyl based lacquer and fillers and/or pigments comprises between 85% to 95% by weight of vinyl, between 1% to 10% cellulose, between 1% to 5% by weight of titanium dioxide and between 1% to 5% by weight of 30 magnesium oxide.

11. A method according to claim 9 or 10 wherein said moisture barrier emulsion comprises between 50% to 80% by weight of water, between 20% to 50% by weight of polyvinylidene chloride and between about 1% to 5% by 35 weight of wetting agents.

12. A method according to claim 9 or 10 wherein said moisture barrier emulsion comprises substantially 70% by weight of water, 28% by weight of polyvinylidene chloride and 2% by weight of wetting agents.

13. A multilayer printable sheet structure substantially as hereinbefore described with reference to the example.

14. A method substantially as hereinbefore described with reference to the example.