GB2120168A - Production of shaped ornamental flat articles - Google Patents

Abstract

A process for the production of a cut printed sheet of plastics material comprises the steps of: (a) bringing the sheet of plastics material into contact with a transfer sheet bearing an image comprising one or more sublimable dyestuffs; (b) heating the sheet of plastics material, capable of being printed by the sublimable dyestuff(s), in contact with the transfer sheet to a temperature and for a time sufficient to cause sublimable dyestuff to sublime and transfer to the sheet of plastics material to print it; and (c) whilst the plastics material is still sufficiently soft, die-cutting it. The sequence heating, die-cutting, sublimation printing is less advantageous.

Description

SPECIFICATION Production of shaped ornamented flat articles This invention is concerned with improvements in a relating to the production of shaped, ornamented flat articles.

Examples of shaped, ornamented flat articles are coasters, table mats, plaques and the like, all comprising a shaped piece of flat, board-like, material having pattern or ornamentation on one surface thereof.

Another class of shaped, ornamented flat articles are toys and games of the sort comprising one or more generally flat shaped pieces which are adapted to engage with each other (as in a so-called jig-saw puzzle) and/or in appropriately shaped depressions or apex: tures in a board or tray.

The shaped pieces for such toys and games are made, for example, from wood (commonly plywood) by sawing (e.g. jig-sawing) the pieces to shape, from paper-board by a diecutting process, and from plastics materials by moulding processes Of these processes, the die-cutting process is generally the most economic but, unfortunately it can only be employed for the fabrication of the shaped pieces from paper board.

Whilst paper-board is sufficiently robust to be acceptable in many instances, this is not the case, for example, when the toy or game is intended to be used by young children or is intended for repeated use. Shaped pieces formed of plastics material are generally more robust than those made of paperboard and thus are more suitable for repeated use by young children.

However, as noted above, they cannot be produced by a die-cutting process and it is an object of the present invention to provide a process for the production of the shaped pieces from plastics material by a die-cutting process.

One surface, the upper surface, of the shaped pieces is generally provided with patterned ornamentation so that, for example, when the pieces are correctly assembled they form a complete picture.

It has now been found, in accordance with the present invention, that by utilising a particular process, namely a dry transfer printing process, for producing an appropriately patterned image on the surface of a sheet of an appropriate plastics material it is possible to produce a printed sheet of the material which can be cut into a desired configuration by a die-cutting operation. This process is also very suitable for the production of other flat shaped articles such as the table mats etc mentioned above.

Dry transfer printing processes are wellknown and, basically, comprise the steps of bringing a substrate to be printed into contact with a transfer sheet bearing an image comprising one or more dyestuffs capable of subliming at elevated temperatures, typically 80-220"C, with the image in contact with the surface of the substrate to be printed; and heating the transfer sheet in contact with the substrate for a time and at a temperature sufficient to cause sublimable dyestuff on the transfer sheet to sublime and transfer to the substrate and thereby print it. The substrate of the transfer sheet is commonly paper although other thin substrates such as those formed of plastics material may also be employed provided that they do not soften appreciably under transfer printing conditions and that they freely release dyestuff under such conditions.

During the course of the dry transfer printing process the substrate to be printed is itself heated and it has now been found that this heating serves to sufficiently soften or modify the physical characteristics of certain plastics substrates to a degree that they are susceptible of cutting into shaped pieces by a diecutting operation.

Broadly, therefore, the invention provides a process for the production of a cut printed sheet of plastics material which comprises the steps of: (a) bringing the sheet of plastics material into contact with a transfer sheet bearing an image comprising one or more sublimable dyestuffs; (b) heating the sheet of plastics material, capable of being printed by the sublimable dyestuff(s), in contact with the transfer sheet to a temperature and for a time sufficient to cause sublimable dyestuff to sublime and transfer to the sheet of plastics material to print it; and (c) whilst the plastics material is still sufficiently soft, die-cutting it.

(The operations of transfer printing and diecutting may be reversed and in this case it is necessary to warm the plastics sheet before die-cutting and problems may be encountered in printing due to the fact that the edges of the cut pieces are rounded, due to the diecutting operation, and it can be difficult to print upon the rounded edges).

The transfer sheet may be separated from the printed plastic sheet either before cutting the latter, i.e. between steps (b) and (c), or after cutting the sheet, i.e. after step (c), if as is commonly the case the transfer sheet is formed of a material which can readily be diecut. However, it is generally preferred to remove the transfer sheet from the printed plastic sheet before cutting the latter since it may then be recovered as a single sheet.

The sublimable dyestuff(s) employed must be capable of printing upon the plastics material or, conversely, the plastics material must be capable of being printed by the sublimable dyestuff(s). Examples of sublimable dyestuff are disperse dyestuffs which may be printed upon polar plastics materials. The plastics material is suitably a thermoplastic material and examples of suitable polar thermoplastics materials include polyvinyl chloride polyesters, polyamides and acrylic polymers.

Sublimable disperse dyestuffs capable of printing upon polar plastics substrates are commercially available under the trade name "Sublaprint", and, thus, examples of particular dyestuffs for printing upon polyvinyl choride substrates are "Sublaprint" Orange 70007, "Sublaprint" Red 700275, "Sublaprint" Blue 70038 and "Sublaprint" Yellow 70001 (all available from L.D. Holliday Et Co Ltd).

The dry transfer sheet used in the transfer printing process may be produced by printing a substrate, e.g. a paper substrate, with one or more inks containing appropriate sublimable dyestuffs in an appropriate pattern by, for example, screen printing or offset lithography, as is well known in the transfer printing art.

The thickness of the plastics sheet material is suitably from 1 to 10 mm, preferably from 3 to 7. It should be noted that not all plastics materials are capable, in sheet form, of being satisfactorily die-cut after heating for a time and at a temperature to effect transfer printing. It is, however, a matter of simple experiment to determine whether a particular plastics material is suitable. Further, it has been found that, in order to obtain acceptable diecutting, the plastics sheet material should be relatively dense foamed material, that is a foamed plastics material in which the bubbles or cells are very small.A particular example of foamed sheet material for use in accordance with the invention is a polyvinyl foamed sheet sold under the trade name "Foamex" manufactured by the company "Airex" of Switzerland.

The time and temperature at which step (b) of the dry transfer printing operation is carried out will depend on the nature of both the sublimable dyestuff(s) and the nature of the sheet of plastics material. The temperature of printing must be sufficient to cause the sublimable dyestuff(s) to sublime without adversely affecting the material of then plastics sheet whilst at the same time sufficient softening the plastics material to enable it to be die-cut.

Similarly, the pressure of printing should not be so high as to adversly effect the sheet of plastics material.

For example, when using the foamed material "Foamex" referred to above together with the "Sublaprint" dyes referred to above, transfer printing is suitably carried out for a period of from 20 to 1 80 seconds at a temperature of from-80 to 1 50 C and at a pressure of 3-5 p.s.i.

The printed, cut sheet produced in accordance with the invention may be used as it is a mat or the like as a toy or game, e.g. as a jig-saw puzzle. IrE this latter case, after production it may be wrapped as it is or may be separated into component pieces and boxed.

Where the printed, cut sheet is intended for use in the manufacture of a toy or game of the sort comprising a board or tray having depressions into which the shaped pieces fit, it is suitably printed and cut to form a sheet bearing a number of aperture-defining cuts and then backed with a sheet of material so that the backing and apertures in the printed sheet together define depressions in the overall assembly. The backing sheet is also suitably formed of plastics material and may be bonded to the printed, cut sheet by means, for example, of a suitable adhesive.

In order that the invention may be well understood the following examples are given by way of illustration only.

EXAMPLE 1 A sheet of "Foamex" expanded rigid PVC, 3 mm thick was brought into contact with a transfer comprising a sheet of paper carrying an image of a clown, the arms, trunk, head and legs of which were printed in four colours using the particular dyes listed above. The printed surface of the transfer was in contact with the "Foamex". This assembly was placed in a twin heated platen press both platens of which were at a temperature of 1 40 C. The press was closed and the assembly was subjected to a pressure of ca 3 p.s.i.

for 30 seconds. The assembly was then removed and the transfer sheet peeled off leaving a 4-colour transfer ring on the "Foamex".

Without allowing the "Foamex" to cool appreciably the sheet was then cut in register with the print using steel rule dies mounted on a wooden backing. Shortly after cutting the sheet was removed from the die by means of a conventional vacuum device. The cut sheet was then backed by glueing a sheet of 2 mm card to the border leaving the parts of the figure free to be removed and reassembled in place, thus constituting a simple toy.

EXAMPLE 2 A sheet of "Foamex" 6 mm thick was transfer printed in the manner of Example 1 using a transfer printed with circular coloured designs. The shee was similarly die cut around the printed circles to provide a number of deocorated table mats or coasters.

EXAMPLE 3 A transfer printed with a woodland scene using the aforesaid dyes was applied to a sheet of "Foamex" 3 mm thick following the procedure of Example 1. It was then die-cut in two directions at right angles using dies of the tranditional interlocking shape to provide a jig saw puzzle.

EXAMPLE 4 The procedure of Example 1 was followed using a sandwich of two transfers with the "Foamex" sheet in the middle. One transfer was printed with a circle, square, triangle and diamond each in a different colour. The other transfer was printed in a single colour with the words "circle" etc. in reverse lettering and in register with the respective shapes printed on the other transfer. The resulting printed "Foamex" sheet was die cut in register with the coloured shapes and backed as in Example 1.

The result was a simple educational aid suitable for nursery school use.

Claims (4)

1. A process for the production of a cut printed sheet of plastics material which comprises the steps of: (a) bringing the sheet of plastics material into contact with a transfer sheet bearing an image comprising one or more sublimable dyestuffs; (b) heating the sheet of plastics material, capable of being printed by the sublimable dyestuff(s), in contact with the transfer sheet to a temperature and for a time sufficient to cause sublimable dyestuff to sublime and transfer to the sheet of plastics material to print it; and (c) whilst the plastics material is still sufficiently soft, die-cutting it.

2. A process as claimed in claim 1 in which the plastics material is a polar thermoplastic material.

3. A process as claimed in claim 1 or claim 2 in which the plastics material is a foamed plastics material.

4. A process as claimed in claim 1 substantially as hereinbefore described with reference to the Examples.