GB2141071A - Using dry transfer sheets - Google Patents

Abstract

By transferring dry transfer letters from a dry transfer lettering sheet onto a receptor which yields under the applied pressure, e.g. a sheet of paper for example mounted on a soft material, such as a foam plastics pad, or mounted on a lightly spring loaded platform, they are adhered to the receptor evenly but not too firmly. A legend built upon such a receptor can be removed as a whole using an adhesive transfer tape and then repositioned e.g. to enable it to be laid down where desired on a desired final surface, with the transfer tape acting as the carrier sheet of a simulated "dry transfer material" bearing the transferable legend. The degree of yield of the receptor preferably corresponds to a softness factor (as defined by a test described in the specification) of 0.15 to 9.0. <IMAGE>

Description

SPECIFICATION Using dry transfer sheets This invention relates to using dry transfer sheets.

Dry transfer sheets have become well known in recent years as an important aid to graphic artists. In particular, dry transfer lettering sheets are available in a very wide range of type styles and sizes, particularly under such Registered Trade Marks as LETRASET INSTANT LETTERING, PRESTYPE AND TRANSPLUS.

In all such materials, a preformed indicia image, usually formed of printing ink applied by screen printing, is adhered where desired by the user of the dry transfer sheet by the application of pressure. The indicium bears a thin coating of a relatively non-tacky pressure sensitive adhesive and this is used to attach the indicium where desired.

In recent years, techniques have been developed which involve the application of dry transfer indicia to a first substrate followed by the removal of those indicia from that substrate and their subsequent application to a further substrate. For example, published European Patent Application No: 0058066 describes such a system, and commercially equipment is available for putting the system into practice (e.g. the Letraset WP4 kit).

Such systems separate the steps of composing the desired legend on the one hand and positioning it where desired on the final receptor on the other. Such separation improves the final result and reduces the amount of "false attempts", e.g. where the letter spacing is unsatisfactory in a word, that word need not be removed from the final artwork - it is simply discarded and is correctly spaced word made up and then applied.

In such systems, a process step must be effected e.g. wetting, to break the initial bond between ink characters and initial receptor. This is inconvenient. We have now found that if the initial receptor is soft or not firmly supported or yielding during the initial transfer step, a wholly dry system may be created where the ink letters are transferred twice, first from a dry transfer material and second from a simulated "dry transfer material" made by the user.

Thus, according to a first feature of the present invention there is provided a method of using a dry transfer sheet which comprises transferring symbols, by the application of pressure using a stylus in the area of each symbol to the rear surface of a carrier sheet constituting part of the dry transfer sheet and subsequent removal of the carrier sheet, to a receptor surface, and thereafter removing the dry transfer symbols adherent to the receptor surface from that receptor surface, wherein during the transferring process the pressure applied by the stylus to the assembly of dry transfer sheet and receptor surface is moderated by displacement of the surface under the application of pressure, the resilience of the surface nevertheless being sufficient to cause the dry transfer symbols to adhere to the receptor surface, and where the application of pressure serves to weaken or break the bond between the symbol and the carrier sheet.

One way of proceeding is to provide that, during at least the transferring process, the dry transfer sheet is manipulated on top of a soft surface having a softness factor of 0.15 to 9.0 (as hereinafter defined). The soft surface may be the surface of a soft material as such, or it may be the surface of e.g. an intermediate receptor sheet which is laid on such material. In place of soft material there may be used a simulated yielding surface, e.g. a sheet of relatively rigid material supported on springs and forming a movable platform set in a fixed surface.In such a case the dry transfer sheet is manipulated with the area containing the symbol to be transferred over the platform with the surrounding areas of the dry transfer sheet supported on the fixed surface, and the indicia being transferred either directly on to the sheet of relatively rigid material or on to a sheet e.g. of paper placed thereon.

By working in this way it is possible to transfer successive symbols on to an intermediate carrier sheet or other surface which serves as the receptor in lightly adherent and very evenly adherent fashion so that they may all be removed from that sheet easily and guaranteeably together e.g. using a low tack pressure sensitive adhesive tape, which then simulates a strip of dry transfer material. They may subsequently be re-transferred to a further desired position, as a whole, by rubbing down from the adhesive tape in the normal fashion of using a dry transfer material. The adhesive tape may then be reused. Alternatively, an assembly of an adhesive tape and symbols may be used as an adhesive label.

In using the system in which a legend is first assembled by successive transfer on to the soft surface, then lifted therefrom by an adhesive tape and subsequently transferred to a final receptor surface in the manner of a dry transfer, the adhesive tape constituting the carrier sheet for such dry transfer, because the initial bond to soft surface is both low and even, the sequential set of transfer steps may be reliably effected.

Typical materials having bulk softness and suitable for providing a soft support surface are thin layers of foam rubber or plastics material or a sheet of soft plastics or rubber. The deformation of the surface when' localised pressure is applied to the rear of the transfer sheet to transfer the symbol limits the degree of pressure which can be applied and accordingly limits the adhesion of the dry transfer symbol to the surface or to an initial receptor sheet thereon. On the other hand, the soft surface is not so soft that it is impossible to generate sufficient pressure to secure transfer.

The softness of a support surface may be measured as follows: a weighted standard probe consisting of a shaft having a hemisphere on its lower end of diameter 3.175 mm, and of total weight 50 g, is held with the shaft vertical and the plane face of the hemisphere horizontally upwards. The surface is then moved on a support to touch the lowest point of the hemisphere and the height of the support noted. The probe is then released and the support and sample raised to bring the probe back to its previous position 1 5 seconds after it was released. The amount in mm by which the support and sample have to be raised to achieve this, conveniently measured using a cathetometer, is the softness factor.

The surface may be made of a unitary material such as polyester foam. However the soft surface may also be made of a composite material, for example a block of polyester with a thin flexible sheet of plastics material such as polyethylene terephthalate or thin rubber on its surface.

If the surface is to be relatively rigid, but resiliently supported, this is conveniently achieved by the use of simple apparatus, for example consisting of a drawing board having set therein a lightly sprung platform on which a sheet of receptor material may be mounted. Conveniently, the platform is of elongate strip shape, and receptor sheets may be provided in the form of strips of paper which fit the platform. Such strips are commercially available for use in so-called word-positioning systems, e.g. WP2 strips available from Letraset Limited.

The accompanying drawing shows, by way of example, suitable apparatus. It consists of a hollow baseboard 1 having a central elongate aperture 2 in which is set a plate 3. The plate 3 is supported on a foam cushion mounted in the baseboard, and has laterally projecting lugs which abut the underside of the top skin of the baseboard 1, under the action of the foam cushion, which is slightly compressed, so that its upper surface is coplanar with the top of baseboard 1.

The upper surface has a coating of low tack adhesive so a paper strip may be temporarily adhered thereto and peeled therefrom after transfer of symbols to the paper from a dry transfer sheet. In use, the transfer sheet is laid on top of the board with the desired symbol in the desired position over aperture 2, and the back of the carrier sheet then manipulated, e.g. using a ballpoint pen, to transfer the symbol to the paper on plate 3.

The following Examples will serve to illustrate the invention.

EXAMPLE 1 A soft support was made by laying a piece of plastics foam 36 mm. thick on a drawing board.

The plastics foam, of unknown origin, had a density of 0.021 g.s.m., and a softness factor of 5.5 mm A receptor sheet of laboratory filter paper (Whatmans No. 4) was placed on the foam pad and letters were then transferred thereto from a sheet of dry transfer materal using a spoon burnisher. The letters transferred were 24 point size capitals.

A transfer tape was manufactured by coating polyethylene terephthalate film (75 microns thick, 542 Melinex ex l.C.I.) with a silicone coating at a dry coating weight of 8 g/m2. The formulation of the coating composition was as follows: (parts by weight) Solvent (Exsol 140/165, ex Esso 266 parts (Syl off 7046 ex Dow Corning) 200 parts (Syl off 7047 ex Dow Corning) 20 parts (DC 297 ex Dow Corning) 2 parts {Q 27089 ex Dow Corning) 36 parts The coating was applied by a 72 meyer bar and the wet coating cured at 120"C for a few minutes to provide an adhesive transfer tape.

The transferred legend could be removed from the filter paper by placing the transfer tape thereover and rubbing it gently into contact with the legend using light finger pressure, with the filter paper and legend still supported on the foam base in order again to prevent too high an application pressure adhering parts of the legend to the filter paper too strongly to enable their removal. On pulling away the adhesive transfer tape, the legend was cleanly lifted from the filter paper. The transfer tape bearing the legend could then be used in fashion analogous to the normal use for dry transfer sheet i.e. the tape was laid legend side down on the desired final receptor surface and the area of the legend worked over using a burnisher, ball point pen or the like. This adheres the individual letters of the legend to the receptor more firmly than they are adhered to the adhesive transfer tape which may then be peeled away to leave the legend firmly adherent to the desired final receptor surface. The adhesive coating on the adhesive tape peels away from the surface with the adhesive tape backing.

EXAMPLE 2 Example 1 was repeated but using, instead of 24 point size letters, 10 point size letters. In order to secure optimum results, the formulation of the coating composition used to form the adhesive transfer tape was modified by changing the quantity of Q 27089 contained therein from 36 parts by weight of 54 parts by weight. Similar satisfactory results were obtained.

EXAMPLE 3 The apparatus of Fig. 1 was used. The foam beneath plate 3 was type DECLON 145 ex Declon Foams Ltd. and the displacement factor was 8.76 mm.

Letraset (Registered Trade Mark) WP2 sheets were adhered to plate 3 and legends transferred thereto using a spoon burnisher. The letters transferred easily and cleanly, and could then be picked off reliably and simply using an adhesive tape as used in Example 1, whereafter they could be transferred together to the desired final receptor.

Claims (8)

1. A method of using a dry transfer sheet which comprises transferring symbols, by the application of pressure using a stylus in the area of each symbol to the rear surface of a carrier sheet constituting part of the dry transfer sheet and subsequent removal of the carrier sheet, to a receptor surface, and thereafter removing the dry transfer symbols adherent to the receptor surface from that receptor surface, wherein during the transferring process the pressure applied by the stylus to the assembly of dry transfer sheet and receptor surface is moderated by displacement of the surface under the application of pressure, the resilience of the surface nevertheless being sufficient to cause the dry transfer symbols to adhere to the receptor surface, and where the application of pressure serves to weaken or break the bond between the symbol and the carrier sheet.

2. A method according to claim 1 wherein the manipulation is effected on top of a soft surface having a softness factor of 0.1 5 to 9.0 (as hereinbefore defined).

3. A method according to claim 2 wherein the soft surface is provided by a sheet of foam rubber or plastics material.

4. A method according to claim 3 wherein the soft surface is provided by a polyester foam.

5. A method according to claim 1 wherein the soft surface comprises a paper receptor sheet supported on a sprung platform set in a fixed surface, and the dry transfer sheet is manipulated with the area containing the symbols to be transferred over the platform and the surrounding areas of the sheet supported on the fixed surface.

6. A method according to any one of claims 1 to 5 wherein the subsequent removal of the symbols is effected by applying an adhesive tape over the symbols, adhesive side down, and peeling away the tape, bearing the symbols, from the receptor surface.

7. A method according to claim 6 wherein the adhesive of the adhesive tape is such as to permit the symbols to be transferred from the adhesive tape to a desired final receptor surface by laying the tape down on the final receptor surface, rubbing over the back of the tape in the area of each symbol using a stylus, and peeling away the tape to leave the symbols adherent to the final receptor surface.

8. A method of using a dry transfer sheet substantially as claimed in claim 1 and hereinbefore described with reference to any of the foregoing specific Examples.