GB2145972A - Signs and decorations - Google Patents

Abstract

A means of forming signs and decorations on articles of fabric or plastic is described which is of particular value because of its versatility, simplicity and aesthetic advantages. By this method, accurately laid out designs are formed by assembling, as separate sub-units, design elements. These design elements consist of parts of the full design imposed in ink containing vapourisable dye, with an affinity for the fabric or plastic, on paper, foil or film. The paper, foil or film is marked by some means to indicate the relationships of the design elements to each other and/or to marks on a support sheet and this means is chosen to be non-transferable. The marks on the support sheet are generally non-transferable but in certain cases they may form part of the transferable design. When the sub-units are adhered to the support sheet, the marks on the sub-units and on the support sheet allow the design to be assembled with great accuracy and it is then transferred by heat transfer printing to the fabric or plastic. Because the assembly marks are non-transferable, the sign or decoration does not show any of the signs of the construction of the design.

Description

SPECIFICATION Signs and decorations This invention relates to signs and decorations. The terms signs and decorations are used here to include designs of lettering (which includes both letters, figures and typographical symbols), words, phrases, sentences, drawings, sketches, photographs, etc imposed upon a suitable medium for informative or decorative purposes.

Sign materials have been known for some years and are described, for example, in British Patent Spec ifications 1,109,792 nd 1,115,922. Typically, signs are formed from letters die cut or stamped out of coloured, self-adhesive plastic sheets, etc. Such letters are then assembled to form words and phrases.

Often such individual letters are mounted on temporary carrier tiles from which they can be removed for positioning on the final medium. Another means of forming signs or decorations is to use dry transfer materials such as are described in British Patent Specifications 959,670 and 954,459. These dry transfer materials consist of transferable indicia coated with adhesive which enables each indicium to be transferred to a receptor surface. Both types of sign have a number of disadvantages. For example, signs formed from die cut lettering of self-adhesive plastic sheet tend to be damaged by abrasion and by cleaning; dry transfer lettering generally unsuitable for exposure to atmospheric conditions, sunlight, etc.

It has been suggested to protect dry transfer lettering by the use of a glass or plastic cover through which the lettering is visible but this adds to the cost and reduces the visibility and appearance of the sign. It has also been suggested in British Patent Specification 2,005,596 to heat bond the indicia to the back of a transparent sign sheet which then acts as protection means for the indicia; a coloured background may optionally be provided against which the indicia may be viewed. A way of forming coloured indicia from black or white transferable indicia is described in British Patent Specification 2,077,187 in which coloured blocking foil is adhered to the indicia held on an intermediate temporary support.The foil-blocked (and therefore coloured) indicia may then be adhered to the back of a transparent sign sheet as above which may also be provided with a background of contrasting colour. These techniques, whilst providing signs of improved properies or appearance, are complicated to employ and require expensive materials and equipment. Another known means of decorating substrates such as certain textiles and plastics is diffusion transfer printing. In this method a sublimable dye is incorporated in an image in printing ink on a suitable supporting medium such as paper which, when heated in contact with the substrate causes the dye to diffuse into the substrate. The substrate is generally a thermoplastic and such a process has been known for many years eg in British Patent Specification 1,518,343.It is important to distinguish between this heat transfer process in which dye molecules diffuse into the sign material and that described in British Patent Specification 2,005,596 in which the indicia composed of pigment and adhesives are transferred by heat to the surface of the sign material and do not diffuse into the body of the material. The diffusion heat transfer process may be used to form signs by, for example, preparing artwork for the sign by applying dry transfer letters to a suitable support (such as paper or card) and then forming on a receiver an image of this artwork containing sublimable dye by an electrophotographic process such as is described in British Patent Specification 1,497,457. The sign is then made by heating the receiver with the image in sublimable dye in contact with the sign material.In some cases, it may be necessary to reverse the image as in British Patent Specification 1,565,051 in order to have a right reading image on the final sign. Unfortunately, the electrophotographic process, whilst giving excellent images of the artwork, cannot be set up so that there is a complete absence of sublimable dye in the areas of the image where no design or lettering is intended to be present. There is always present a small amount of sublimable dye in the form of speckles which during the heat transfer process, produces coloured or black speckles (according to the dye colour) in the background of the sign or decoration.These speckles are aesthetically unattractive and whilst they may sometimes be scraped off the receiver before transferring the image to the material to be printed, this cannot be done with complicated or intricate signs or designs because of the danger of interfering with the wanted parts of the dye image. In the preparation of all of the signs or decorations described above, it is necessary at some stage of the process to assemble the design in an aesthetically satisfactory manner. For example, in a lettered design, the letters have to be correctly aligned and spaced. When dry transfer lettering is used, the alignment of the letters is often achieved by drawing a temporary guideline (for example, in pencil) on the material to which the letters are first to be transferred.This guideline must later be removed, for example by the use of an eraser, which can sometimes damage the dry transfer lettering. To achieve the correct spacing, transferable spacing marks are sometimes incorporated in the dry transfer sheet. These are transferred to the material to which the dry transfer letters are being transferred and when they have served their purpose as spacing marks, they must be removed by knifing or by the use of drafting tape. In either case, there is a danger of damaging the wanted lettering. Additionally, the precision of positioning using both the guideline and the transferable spacing marks is less than is desirable because the translucent carrier sheet for the indicia to some extent obscures these markings.In addition, only a very limited amount of spacing mark information can be included with the indicia because at some stage of the operation it must be removed preferentially from the material to which the indicia are being transferred and the greater the amount of material to be removed, the greater is the danger of damaging the wanted design.

Because of this limitation in the amount of spacing information, the less precise can be the spacing andi or alignment. In the case of self-adhesive die cut letters of vinyl or other plastic sheet, it has been proposed in British Patent Specification 2,016,192 to releasably adhere these letters to split backing tiles whose spacing is assisted by one or more stepped notches at one or more corners of each tile. The innermost vertical sides of each notch are then abutted to give the desired spacing. Unfortunately, although improved spacing may be obtained by this method, because at some stage of the sign making process the backing tiles must be removed from the adhesively-backed letters to allow them to be adhered to the final receptor, the spacing or alignment may be upset at the point at which the letters are no longer repositionable.

I have now found a way of forming signs and decorations which overcomes the disadvantages of the previously known methods and which is versatile and inexpensive to perform.

According to the present invention there is provided a means of forming signs and decorations on articles of fabric or plastic by heat transfer printing with accurately laid out designs comprising assembling, as separate sub-units, elements of the design imposed upon transparent, translucent or opaque paper, foil or film in ink containing vapourisable dye in which the sub-units carrying the design elements are marked by a non-transferable means to indicate their relationships to each other and/or to transferable or non-transferable marks on a support sheet or to marks visible through the article to be decorated or through a transparent or translucent support sheet.

Thus, in particular, the signs or decorations which it is desired to impose upon articles of fabric or plastic may be any of an almost infinite range of designs. For example, they may be names or slogans together with photographs, sketches or caricatures of artists, singers, politicians or other well known figures. Such designs may be required to be imposed upon T-shirts, sweaters, caps, blouses, dresses or other garments or textiles. It may be desired to impose the design in more than one place on the article in which case it may be essential that the designs in all places are identical. Designs may be in a single colour or in multiple colours. For example, a name may be assembled from sub-units which are individual letters of the same type style and size but which are of several colours.Or the same sub-units may consist of Oshadow' letters in which the shadows are a different colour to the main body of the letters.

Many such possibilities suggest themselves once the basic invention is disclosed.

Another possibility is signs for use in garden centres in which the name of the proprietors plus a coloured photograph of a plant or shrub to be sold plus the price plus a short descriptive phrase concerning the plant or shrub may all be assembled as sub-units to be heat transfer printed on to suitable plastic for display with the plant. Thus, if the price should change, a slightly different sub-unit assembly only will be needed. In the same way, easily modifiable restaurant menus may be prepared in which only a few subunits need to be placed to show changed dishes or prices, etc. In these cases, the major sub-units may be printed in multiple colours by, for example, four colour lithography or gravure.Thus many sub-units may be printed at a low cost per sub-unit and these are only transferred to fabric or plastic when they are required since the fabric or plastic is usually the most expensive item in the production of the sign or decoration. Other possibilities are decorative or descriptive labels in shops and stores. Very many such possibilities come easily to mind. By the use of such assemblies of sub-units, large designs may be prepared from a number of small design elements. For example, transparent or opaque panels for use in exhibitions and displays are quite feasible or the designs may be used as murals or decorative surfaces in or on buildings or vehicles, etc.

The heat transfer process will work satisfactorily with a number of materials which are, generally speaking, thermoplastics. Thus the articles to be decorated may be composed of a textile material, a nonwoven article, paper or any surface (such as metal, plastic, wood,etc) impregnated, coated or covered with or consisting of an acrylic polymer, polyamide, polyester, epoxy resin, vinyl resin or polyurethane.

Preferred receiving materials are textiles containing 50% or more of surface fibres of polyester or polyamide or a sheet of plastic material or plastic coated material where the plastic is a linear or crosslinked polyester or a polyamide. Polyethylene terephthalate or nylon 66 sheet with oriented molecules, optionally containing a white or coloured pigment are materials even more to be preferred. Such plastic sheets may be adhered to a support of paper, plastic, metal, etc or they may be coated with a thin metallic film or other coating on the opposite face to that to which the design is to be transferred.The heat transfer process is advantageously carried out by heating the design in contact with the fabric or plastic at a temperature above 140"C and preferably above 1700C. Obviously the preference for this temperature imposes limits on the thermoplastics which may be employed since they must be stable at the transfer temperature. The heating operation is preferably carried out for between 10 and 60 seconds and more preferably for between 15 and 40 seconds.

An important aspect of this invention is the accuracy with which the designs may be laid out because the aesthetic value of designs with the optimum alignment, spacing and reproducibility is much greater than that of designs in which these parameters cannot be well controlled. Several factors lead to this greater accuracy. Firstly, the non-transferable means can be placed extremely accurately in relation to the imposed transferable elements on each design sub-unit. Secondly, the non-transferable means may comprise virtually any amount of information because it does not have to be removed from the design before the design is used ie before it is transferred to the fabric or plastic.Thirdly, once the sub-units have been assembled on the support sheet, they do not need to be further disturbed to transfer the design to the fabric or plastic (in contrast to die cut adhesively-backed plastic letters on carrier tiles). Thus with this invention it is possible to position the design elements in the sign or decoration on the fabric or plastic to within 0.1 mm or less of their desired position. This distance may easily be measured in a chosen direction, for example, by the use of a travelling microscope with its hair-line aligned to traverse a real or imaginary line indicating the desired position of some part of a design element. The difference, measured in the graticule, between the hair-line and the chosen part of the design element represents the accuracy of positioning the design element in the chosen direction.In this method, the real or imaginary line should be selected to be perpendicular to the chosen direction of the accuracy measurement.

The assembly of the sub-units of the design is preferably accomplished by the use of a repositionable adhesive on the back of the sub-unks. In this way, slight adjustments may be made to the positions of the sub-units as they are being placed, so as to achieve the maximum accuracy. The adhesive must be stable under heat and pressure of the levels used to transfer the design to the fabric or plastic and it must not give off steam or vapour which would interfere with the dye transfer process. Several commercially available adhesive will meet these criteria.

The sub-units of the design may contain any elements which are formed in transferable dye. The subunits may be large or small and the transferable elements may or may not extend to the edges of the paper, foil or film of which the sub-units are formed. The imposition of the transferable dye (contained in a suitable ink medium) may be by hand-drawing or painting, by printing by any of the known means such as flexography, gravure, letter-press, screen-printing, lithography, etc or by any other means which leads to a sharp and distinct design element free from speckle or other extraneous transferable item. It is necessary that the transferable elements and the non-transferable means can be imposed in a pre-determined and accurate relationship to each other. When the sub-units are assembled on the support sheet they may butt together or overlap or have gaps between them.However, it is preferable that they butt together and that they do not overlap because the double thickness of the paper, foil or film can cause an indentation in or on the fabric or plastic which may be quite soft at the transfer temperature. If the sub-units are to overlap, it is preferable that the paper, foil or film is as thin as possible, consistent with stability for handling. Of course, the paper, foil or film must be stable at the heat transfer temperature. If the sub-units do overlap, of course, the overlap should not include any of the required design elements.

Many materials such as paper or metal foil such as aluminium foil may be used for the sub-units. For the sake of good receptivity to the ink, low cost and ease of supply, paper is preferred and a lightweight, chemically pure grade manufactured specially as a transfer printing article is a suitable product since many ranges of suitable inks are available for use with and are specially compatible with such papers.

The design elements may be printed as they are required to appear on the fabric or plastic or they may need to be printed as a mirror image of their final appearance. If they are to be viewed through the article (ie if it is transparent plastic film or sheet) then the elements do not require to be present as a mirror image. If, however, they are to be viewed on the surface of the article, then they must be in mirror image form. Of course, if the design elements forming the sub-units are imposed on a transparent foil, then they must be imposed as a mirror image but they may be assembled not laterally inverted. In this case, the repositionable adhesive must be on the same side of the sub-units as the dye-carrying design elements. The non-transferable means may be on either side of the foil, however, as long as it is accurately registered with the design elements.The use of transparent sub-units is a very useful way of avoiding the construction of designs in mirror image form, which may sometimes be more difficult or less convenient than right way round assembly.

Inks containing vapourisable dyes are readily available in ranges suitable for application by the techniques mentioned above for the imposition of the design elements on the sub-units. It is desirable when using one application technique eg screen printing to use a range of inks supplied by one manufacturer because in such a range, the vapourisable dyes will have been chosen to be especially compatible. That is to say, they will transfer to a similar extent when subjected to similar time and temperature treatments in the heat transfer process. This is necessary because if the sub-units comprising a complete design contain transferable dyes of different energies, then there may be shade or colour differences or colour intensity differences in the final produce ie the design formed on the fabric or plastic.In general, transferable dyes are classified as high, medium or low energy according to the time and temperature conditions which are required to cause them to transfer. If the design elements are imposed on the sub-units by different techniques, then it is desirable to ensure that the energies of the vapourisable dyes present in the different inks are the same or are similar. It is better if the dyes are chemically identical where it is desired to produce design elements of the same colour by two or more different methods of imposition.

Such chemically similar dyes are often identified by their Colour Index (or CI) number in the publications of the American Association of Textile Chemists and Colourists (AATCC) and information may often be obtained from the ink manufacturers about the dyes used in their ink ranges.

A number of non-transferable means may be employed to indicate the relationships of the design elements. For example, the sub-units may be shaped to fit together accurately or to be located against a printed non-transferable outline on the support sheet. The sub-units may possess nicks or notches which are intended to butt together. The use of stepped notches in the carrier tiles of die cut sign letters is exemplified in British Patent Specification 2,016,192. However, such notches are not easy to use and do not locate the individual letters accurately as regards their perpendicularity. The preferred method in the present invention is to impose guide lines on the sub-units in ink not containing any transferable dye.

Because these guide lines will not transfer to the fabric or plastic, they may be provided in quantity and may give considerable information about the positioning of the design elements. If it is desirable, such guide lines may be imposed in several colours so that it can easily be seen which relationship to use in given application circumstances. Since the guide lines will not transfer, there is never any need to remove them prior to transferring the design and there is therefore never any danger of damaging the design. If desired, the several sets of guide lines on the sub-units may be coloured to match sets of guide lines in corresponding colours on the support sheet. Guide lines may also be full or interrupted to give additional information.In order to obtain the best positioning it is desirable that thin guide lines are used and that the thickness is the same on both the sub-units and the support sheet. In this case, the sub-units may be positioned such that the guide lines appear to be continuous from the support sheet to the subunits and vice versa. For the best accuracy, it is desirable that the guide lines be less than 0.2mm thick.

Alternatively, very accurate positioning may be obtained by having thick guide lines in which the edge of the guide line is used as the position indicator. In this case, very accurate location of the sub-units may be achieved because this edged has effectively zero thickness. Where the 'edge' technique is used, it is preferable that the guide lines are at least 1 mum thick. Of course, the guide lines with this method may be so thick as to be merely a very wide band of colour crossing the sub-unit. In some cases, it may be desirable to superimpose the guide lines on to the transferable elements of the sub-units.For example, if the sub-units are die cut letters which are printed in their entirety with ink containing transferable dye, then they may be assembled on a support sheet, also printed in its entirety with ink containing transferable dye of a different colour to that in the ink on the sub-units. Thus, when the design is formed on the plastic or fabric, since the transferable dye on the support cannot pass through the sub-units, letters of one colour will be superimposed on a background of a second colour. Here, the guide lines must stand out against the inks containing transferable dyes but they must not interfere with the heat transfer printing process. If the inks containing the transferable dyes are light in colour, then the guide lines may be present as darker lines which may be applied before or after the inks containing the transferable dyes.If the inks containing the transferable dyes are dark in colour, then the guide lines should be applied as light, opaque colour which will stand out against the dark inks containing the transferable dyes. In this case, it is desirable that the guide lines be applied after the inks containing the transferable dyes. Of course, in certain cases, it may be possible for the design elements themselves to form the guide lines.

For example, in the above situation of imposing coloured letters on a differently coloured background, both the letter and the support could be printed with the same tartan design in inks containing transferable dyes but colours on the die cut letter sub-units could be different to those on the support. In this case, the lines of the tartan design could be used to align the letter sub-units provided that die cutting and the tartan design were suitably arranged to be in register. As a variant of this technique, non-transferable guide lines could be used to align the letter sub-units with a tartan or similar geometrical design on the support sheet. Other variants of the basic idea are also possible.For example, letter sub-units printed in their entirety with ink containing transferable dye may have superimposed on them in contrasting ink not containing transferable dye a single horizontal line across the centre line of the letters and a single vertical line perpendicular to the horizontal line (the term horizontal in this context is taken to indicate a direction parallel to the base line of the letter design elements). If the vertical lines on the letters are chosen always to have a fixed relationship to the letter shapes, then the correct letter spacings may be set when laying out the design by reference to a table of correct vertical line spacings for letter pairs. Such a table may be constructed by a person skilled in the art of typographical design so that an unskilled person forming the design from letter sub-units can easily do so.This would be done by the unskilled person aligning the centre line on the letters with a horizontal line on a support sheet and setting the vertical lines on the letters the appropriate distance apart as indicated on the table. If necessary, a number of 'correct' spacings may be given for each letter pair to give close or wide letter spacings, or the 'correct' spacings may be given and these may be increased or decreased by a chosen factor. If it is so desired, to save the work of imposing the guide lines on the letter sub-units, the horizontal and vertical guide lines may be replaced by small, pointed projections at the top, bottom and sides of each letter sub-unit so that the side points would be aligned with a horizontal line on the support sheet and the top and bottom points would represent the vertical line to give the desired spacings from the table.The pointed projections would be formed during the die cutting process and they would be removed by a knife or be prevented from appearing on the fabric or plastic by covering them over with small pieces of adhesive paper, etc after the body of the letter sub-unit had been adhered to the support sheet. Some of the possible techniques for forming designs are illustrated by means of Figures 1 to 8. Figure 1 shows eight sub-units on which are imposed (in reverse) as design elements the letters 'A', 'C', 'E', 'N', 'O', 'T', 'S', and 'P'. The heavy, solid black line of which each letter is composed represents ink containing transferable dye. The thin, solid line enclosing each letter plus its sets of interrupted lines merely represents the edge of the sub-unit and in reality is not printed with any kind of ink. The letter design elements are each enclosed by one pair of horizontal dotted lines and up to four pairs of vertical lines composed of dots and dashes. All of these interrupted lines represent ink not containing transferable dye. Thus to assemble the design (say, a word) from these sub-units, a guide line is chosen on a suitable support sheet and the bottom horizontal dotted line of each letter sub-unit is aligned along this guide line. To achieve the correct letter spacing, prior to adhering the letter sub-units to the support sheet, each letter sub-unit is trimmed with scissors or some other suitable means along the appropriate pair of vertical interrupted lines so that the vertical edges of the sub-units butt up against each other to give the required spacing of the letter design elements after transfer of the design to the fabric or plastic.Thus, if 'C' is to be followed by 'E', the left hand edge of the 'C' sub-unit is trimmed to its interrupted vertical line and the right hand edge of the 'E' sub-unit is trimmed to its interrupted vertical line and the two edges are butted together on the support sheet as the sub-units are assembled in reverse from right to left. In this case, each letter sub-unit has only one pair of interrupted verical lines and so there is only one possible trimming position. However, if 'C' was to be followed by 'A', then a judgement must be made of which vertical lines to trim to on 'A'.In this case, there is no difficulty in choosing the second pair of lines in from the edges of the 'A' sub-unit because, if the outermost pair were chosen, it is very obvious that 'C' and 'A' are too far apart, whilst if the third pair in from the edges were selected, the transferable elements of 'A' and 'C' would overlap and this is clearly incorrect. It should be noted that it is necessary to cut away part of the 'C' sub-unit and to leave on part of the 'A' sub-unit outside the second pair of vertical lines to prevent the sub-unit of letter 'C' overlapping the transferable design element 'A'.In a similar way, all other pairs of letters may be accurately laid out and correctly spaced although there are more possible spacings to select from if, say, 'A' is preceeded by T since both letters have more than one pair of interrupted vertical lines and a degree of judgement must be exercised by the operator in selecting the correct pairs.

Figure 2 shows a single sub-unit bearing the design element letter 'D' in reverse in ink containing transferable dye. In this case, however, the dotted horizontal lines have been replaced by a single, very thick, coloured line not containing transferable dye; this thick, coloured line is represented in Figure 2 by a thick, dashed line. Here, the top and bottom edges of this thick, coloured line are used to achieve the accurate alignment of the bases of the letter design elements. The correct spacing is achieved as with the sub-units shown in Figure 1. Figure 3 shows an alternative means of aligning and spacing letter design elements. In this case, the sub-units are die cut letters coated completely on one surface with ink containing transferable dye. On each sub-unit is imposed, in ink of a contrasting colour, a horizontal and a vertical line of minimum thickness.The ink of this contrasting colour does not contain a transferable dye and does not interfere with the transfer of dye from the design element. Both lines pass through the centre of each letter (although it is not essential for them to do this as long as consistent positions are selected to achieve satisfactory results). The horizontal line is used to base align the letter sub-units and the vertical line is used to space the letters by reference to a table of ideal letter pair spacings (not illustrated). A possible way of employing this method to form a word design is to draw, using a drawing board, on a paper support, a horizontal guide line in ink not containing transferable dye.Vertical guide lines at the appropriate spacings (obtained from the table of ideal letter pair spacings) are then drawn crossing the horizontal guide perpendicularly: these vertical guide lines are also in ink not containing transferable dye.

It is then a simple matter to adhere the sub-units to the support sheet by aligning the lines on the subunits with the support sheet guide lines. Figure 4 shows an alternative means of aligning letter sub-units by the use of temporary, small projections. Figure 5 shows sub-units with one pair of horizontal lines in ink not containing transferable dye plus a single central, vertical line not containing transferable dye. In Figures 4 and 5 techniques, letter spacing tables must be employed as in the Figure 3 method. Figure 6 shows logo, number and word design elements imposed on paper sub-units in ink containing transferable dye. The logo is in ink containing a blue transferable dye whilst the number and word design elements are in ink containing black transferable dye. The dashed lines are layout marks imposed in ink not containing transferable dye.Figure 7 shows a paper support sheet with layout marks (dash-dot lines) imposed in ink not containing transferable dye. Figure 8 shows a garden centre label design prepared by mounting the sub-units of Figure 6 on the support sheet of Figure 7 using the non-transferable means on the sub-units and support sheet to align the design elements. The reversed design is ready for heat transfer printing on to a suitable plastic sheet so that the plastic sheet so designed may be displayed alongside the plant which is to be offered for sale. Very many other such possibilities exist for using this invention, limited only by the imagination.

The support sheet may be formed of any suitable material such as paper, metal foil, plastic sheet or film, etc. It is essential that it can withstand the time and temperature conditions of the heat transfer process and it is also desirable that it is easy to print and is dimensionally stable. The preferred support material is paper of the same type as preferred for the sub-units since this is highly compatible with the sub-units. However, a support sheet may not always be necessary. For example, if the plastic to be decorated is thin transparent foil, then the sub-units may be adhered directly to this foil using a temporary adhesive. In this case, a transparent sheet, marked with guide lines, must be provided to allow the subunits to be accurately positioned. This sheet marked with guide lines would then be placed over the foil which was in turn placed over the sub-units so that all guide lines would be visible. Again, the support sheet may be transparent material in sheet form and a marked sheet may be temporarily positioned beneath the transparent support sheet to allow the sub-units to be positioned. Other similar possibilities are easy to envisage which may offer advantages in certain circumstances.

The marks on the support sheet may be printed guide lines of the various types as described for the sub-units. It is desirable that these guide lines are of a matching style and colour, etc to those on the sub-units for ease of application of the invention. The marks on the support sheet should preferably not contain any transferable dye and, generally, ordinary inks for the various printing processes satisfy this criterion. The suitability of any particular ink may easily be ascertained by carrying out a transfer operation in the heat transfer press normally employed, using the fabric or plastic. The absence of any mark on the fabric or plastic indicates the suitability of the ink. In certain limited cases, some or all of the makers on the support sheet may contain transferable dye. This is where part of the design is imposed on the support sheet in inks containing transferable dye.Applications of this variant will be apparent to anyone skilled in the art.

The following examples will serve to illustrate the invention.

Example 1 A quantity of design sub-units was prepared in which the design elements were reversed letters of the English alphabet in the typeface Helvetica Light. These were screen printed in ink containing a vapourisable dye formulation which on heat sublimation transfer would give a black image. The ink used was MarlerTex TXO1 (supplied by E T Marler Ltd) and the substrate used was Marler Transfer Paper C17 which is a coated art paper for extreme quality. Each of these sub-units was marked with guide lines 0.13mm wide printed in screen printing ink with no vapourisable dye present. The ink used for the guide lines was MarlerAqua AQ08 Leaf Green which had been tested as above to ensure that no transferable dye was present.The guide lines on the letter sub-units were arranged as in Figure 1; that is, a horizontal guide line defined the base of the letters and pairs of vertical guide lines defined the letter spacings for the best aesthetic arrangement. As in the sub-units illustrated in Figure 1, up to four pairs of vertical guide lines were employed for each letter, depending on the letter shape, as described in the text above.

It should be noted that in the case of certain letters (generally, highly curved letters such as CHIC' and QO') that the horizontal guide line indicating the base of the letter actually passes slightly through the letter outline and does not form a tangent to the letter outline as might at first thought be expected. This is because such highly curved letters extend above and below the height of uncurved letters such as 'A', 'N', 'T', etc for aesthetic reasons; unless this design feature is adopted, then the appearance of words formed from the type face would be aesthetically unsatisfactory. This, then explains a feature of Figure 1 I the position of the horizontal guide lines relative to the design elements I which may have appeared to be incorrect in the case of these certain letter elements of high curvature.In the sub-units of this example, only one horizontal guide line was used on each sub-unit (ie the base guide line) as it was not felt necessary in this case to employ a horizontal guide line to define the tops of the letter design elements.

An unskilled operator was then asked to back a number of sub-units with a repositionable tacky adhesive (Scotch Spray Mount manufactured by 3M United Kingdom Ltd) and to assemble them, using a magnifying viewer, on a support sheet of C17 Transfer Paper on which were printed horizontal and vertical guide lines 0.13mm wide in Marler Aqua AQ08 Leaf Green ink. The horizontal and vertical lines formed a grid of squares each of 4.24mm side (approximately equal to 1 pica, a printing measure). The design chosen for the operator to assemble was the world QDIAGRAMMATICALLY' in reverse ie reading from right to left. Since the sub-units were already mirror-imaged in terms of their letter design elements, the total assembly formed a mirror-image of the chosen word.The operator was asked to use one of the horizontal lines of the support grid to align the bases of the letters by allowing the non-transferable lines on the sub-units to fall on the chosen horizontal grid line. The operator was asked to obtain the correct sub-unit spacing by trimming each sub-unit with scissors along the appropriate non-transferable vertical spacing line (taking care not to cut away any of the design element printed in ink containing transferable dye) and then to butt the units together in the correct order. (Where there was more than one possible vertical line to trim to, the operator was asked to select by inspection the one which seemed the most appropriate to give the aesthetically most satisfactory letter spacing.The operator was then timed from the point at which he picked up the first sub-unit to the point at which the design (ie the mirror image word) was completed.

The design was then placed face down in a heat transfer press (A Adkins model Double A Series 6000) in contact with a piece of oriented polyethylene terephthalate film containing a white pigment ('Melinex' Type 226, thickness 250 > , manufactured by ICI) and the pair were heated at 200"C for 40 seconds under the pressure normally applied by this press. At the end of this time, the design and the film were removed from the press and were separated. The word 'DIAGRAMMATICALLY' was imprinted in black on the film; all of the characters were well aligned and had an aesthetically satisfactory spacing. None of the guide lines were present on the film.The total length of the word was measured in mm and the accuracy of the positioning of the bases of the letters was measured by traversing the hair-line of a travelling microscope along an imaginary line joining the base of the 'D' to the base of the QY' and measuring on the graticule the distance from the hair-iine to the bases of the remaining letters (taking into account the requirement that the bases of certain letters were intended to overlap the imaginary line as discussed above). Since some of the letters touch or overlap the imaginary line in more than one place, a total of 24 readings was taken which were then averaged to give a mean accuracy. This figure is tabulated below and the highest reading of the 24 is also given as the worst accuracy'. This whole exercise was then repeated by two more operators. The results are given in Table 1 below.

TABLE 1 The accuracy of assembling the word design 'DIA GRAMMA TICALL Y' using sub-units with non-transferable guide lines.

Operator Time /sect Word length (mm) Mean accuracy (mum) Worst accuracy (mum) 1 800 334.7 0.019 0.024 2 788 334.1 0.018 0.025 3 824 333.4 0.018 0.029 Example 2 (comparative example) The previous example was repeated exactly except that the sub-units of the design were not marked by a non-transferable means to indicate their alignment and spacing. When the word design 'DIAGRAM MATICALLY' was transferred to the polyethylene terephthalate film, the characters were not so well aligned nor well spaced and the overall effect was aesthetically unpleasing. The results from three operators are given in Table 2 below.

TABLE 2 The accuracy of assembling the word design 'DIAGRAMMATICALLY' using sub-units without non-transferable guide fines.

Operator Time (sec) Word length (mm) Mean accuracy (mum) Worst accuracy (mum) 1 893 328.4 0.15 0.21 2 844 329.2 0.14 0.22 3 815 327.3 0.15 0.20 Example 3 Example 1 was repeated but using only one operator producing only one sample of the same design as in Example 1. This was transferred as in Example 1 but in place of the polyethylene terephthalate film was substituted a piece of warp knitted 100% polyester (:Terylene') fabric. In this case, the transfer conditions were 30 seconds at 210"C. Again, an aesthetically satisfactory rendering of the design (the word 'DIAGRAMMATICALLY') was observed on the fabric. None of the guide were present on the fabric.

Example 4 Example 3 was repeated but nylon 66 fabric was used instead of polyester fabric. The transfer conditions were 20 seconds at 195"C. An aesthetically satisfactory rendering of the design word 'DIAGRAM MATICALLY' was observed on the fabric together with the complete absence of the guide lines.

Example 5 Example 3 was repeated but the polyester fabric was replaced by a piece of plastic coated silver satin aluminium sheet (supplied by Charterhouse Xpres, Leicester). An aesthetically satisfactory rendering on the word design 'DIAGRAMMATICALLY' was noted on the plastic coated aluminium sheet. There was no trace of the non-transferable guide lines on the plastic coated aluminium sheet.

Example 6 A design was assembled from three elements on paper sub-units. These three elements were a) the name of a garden centre; b) the name of a shrub; c) a price. All of these elements were laterally inverted and were printed in ink containing transferable dye. Each sub-unit was marked with non-transferable guide lines. All materials used were as in Example 1 except that the garden centre name was imposed in ink containing a blue transferable dye (MarlerTex TX 32). The design elements are shown in Figure 6.

These design elements were assembled on a support sheet as shown in Figure 7 on which were imposed guide lines in ink not containing any transferable dye (MarlerAqua AQ08). The sub-units were assembled as shown in Figure 8 on the support sheet. The design was then transferred to the polyethylene terephthalate film as used in Example 1 under the conditions used in Example 1. A pleasing and attractive 'point of sale' plant label was obtained in which the alignment of the various elements was very accurate and aesthetically satisfactory and which was suitable for external display at a garden centre on a suitable rigid secondary support such as a piece of wood or metal.

Claims (20)

1. A means of forming signs or decorations on articles of fabric or plastic by heat transfer printing with accurately laid out designs comprising assembling, as separate sub-units, elements of the design imposed on transparent, translucent or opaque paper, foil or film in ink containing vapourisable dye in which the sub-units carrying the design elements are marked by a non-transferable means to indicate the relationships of the design elements to each other and/or to transferable or non-transferable marks on a support sheet or to marks visible through the article to be decorated or through a transparent or translucent support sheet.

2. A claim according to Claim 1 where the articles of fabric or plastic are composed wholly or partially of polyester or polyamide.

3. A claim according to Claim 1 where the articles of fabric or plastic are composed wholly or partially of polyester.

4. A claim according to Claim 1 where the articles of fabric or plastic are composed wholly or partially of polyethylene terephthalate.

5. A claim according to Claim 1 where the articles of plastic comprise a polyester coating on a substrate.

6. A claim according to Claim 5 where the polyester coating is polythene terephthalate.

7. A claim according to Claims 1 to 6 where the design elements are laid out to an accuracy of 0.lmm.

8. A claim according to Claims 1 to 7 where the sub-units consist of paper.

9. A claim according to Claims 1 to 8 where the non-transferable means on the sub-units consists of guide lines less than 0.2mm wide.

10. A claim according to Claims 1 to 8 where the non-transferable means on the sub-units consists of shaped projections or indentations of the paper, foil or film in the plane of the paper, foil or film.

11. A claim according to Claims 1 to 8 where the non-transferable means on the sub-units is provided by the shape of the sub-units.

12. A claim according to Claims 1 to 8 where the non-transferable means on the sub-units consists of the edges of guide lines greater than 1mm thick.

13. A claim according to Claims 1 to 8 where the non-transferable means on the sub-units consists of any selection or combination of means as defined in Claims 9 to 12.

14. A claim as in Claims 1 to 13 where the support sheet is paper.

15. A claim as in Claims 1 to 13 where the support sheet is transparent or translucent plastic superimposed over a marked guide sheet.

16. A claim according to Claims 1 to 15 where the marks on the support sheet or guide sheet consist of lines less than 0.2mm thick.

17. A claim according to claims 1 to 15 where the marks on the support sheet or guide sheet consist of the edges of guide lines greater than 1 mm thick.

18. A claim according to Claims 1 to 15 where the marks on the support sheet or guide sheet consist of a combination of marks according to Claims 16 and 17.

19. Design forming sub-units and support sheets as in Claims 1 to 18.

20. Signs or decorations formed by the means defined in Claims 1 to 18.