WO2008097151A1

WO2008097151A1 - Afterglowing sign with fluorescent colour

Info

Publication number: WO2008097151A1
Application number: PCT/SE2008/000052
Authority: WO
Inventors: Sven Thollin
Original assignee: Systemtext Ab
Priority date: 2007-02-08
Filing date: 2008-01-23
Publication date: 2008-08-14
Also published as: SE0700303L; SE530749C2

Abstract

The present invention concerns an afterglowing sign comprising a sign material (1) and afterglowing pigments, where a first layer (2) of afterglowing pigments is applied to the sign material (1) or where the afterglowing pigments are incorporated into the sign material (1), a second layer (3) of fluorescent colour (4) being applied on top of the first layer (2) of afterglowing pigments or applied to the sign material (1) when the afterglowing pigments are incorporated into the sign material (1). Further, an afterglowing sign is described comprising a sign material (1) and afterglowing pigments, where a second layer (3) of fluorescent colour (4), which has enhanced afterglow as a result of the fluorescent colour 4 being mixed with afterglowing pigments, is applied directly to the sign material (1). Further, the use of an afterglowing sign according to the present invention as a safety sign and advertising or information sign is described.

Description

AFTERGLOWING SIGN WITH FLUORESCENT COLOUR

Field of the Invention

The present invention relates to afterglowing signs and their use as safety signs, and signs for advertising and information. Technical Background On the market today a number of afterglowing signs can be found which are used, for instance, for the identification and display of escape routes and emergency exits and also for marking the location of fire-fighting equipment. However, the afterglowing pigments used do not have the right shades of colour to achieve optimal colour reproduction, with conventional printing, both in daylight and, with a coloured afterglow, in the dark. This has hitherto been resolved by accepting that these signs only display afterglowing symbols in the dark, their background colour being perceived as black. Thus, these afterglowing safety signs have only met the colour requirements in daylight and in illuminated spaces since the afterglowing pigments available do not completely meet the requirements both in daylight/artificial light and in the dark.

It is also known from SE 519 842 to employ afterglowing signs printed with afterglowing pigments, which are covered with a screen print of opaque or transparent colour or ink in order to produce, for example, safety signs which meet the colour demands in both daylight/artificial light and, with a coloured afterglow, in the dark. When viewed up close, these signs can give a disturbing impression on account of the screen printing, for example, a striped, chequered or spotty visual impression. Signs with a screen print can also give the impression of a somewhat different colour shade relative to the standard on account of the screen pattern's effect on the visual impression. Especially for safety signs where standardised colour shades and surfaces are used, it is thus desired to come very close to a uniformly coloured impression, and to reproduce the colour shades as accurately as possible. In addi- tion, the reproduction of signs which have relatively large amounts of text may be spoiled by screen printing.

Further, from SE 526 916, it is known to use afterglowing signs printed with afterglowing pigments, wherein a sign material which has a coloured sur- face is used and the colour of this surface shines through the print with afterglowing pigments, the coloured surface of the sign being obtained by printing with an opaque colour on the sign material. A problem with these signs is that the colour shades do not all give an equally good result with respect to colour reproduction and afterglow in the dark. One example is shades of red, which do not work as well as, for example, yellow or green colours. Further, another problem is that the colour reproduction of these signs in daylight is not optimal since certain of the afterglowing colours which are situated outermost on the sign tone down the underlying colours. Even if the opaque colour under the print with afterglowing pigment shines through the print with afterglowing pig- ment none of these signs can reproduce an optimally distinct and sharp colour in daylight. One of the most important areas of application for signs according to SE 526 916 is still as safety signs where reproduction is distinct in the dark. In other words, clearly distinct shades and colour in daylight are not as important when these signs are used as safety signs. The problem with colour reproduction for these signs in the dark for certain special colours, such as red, still stands.

In US 6 074 739, compositions with afterglowing properties are described, the compositions comprising at least one phosphorescent layer and one outer phosphorescent colour layer, the phosphorescent layer including phosphor and a binding agent and the phosphorescent colour layer comprising a colour compound, phosphor and binder. The outer phosphorescing colour layer gives, according to

US 6 074 739, a coloured afterglow, that is to say in the dark, whereas colour reproduction in daylight is relatively weak. One object of the present invention is to remedy the problems described above and to achieve a sign which gives sharp colour reproduction in daylight as well as in the dark, and where the colour reproduction in daylight is very distinct when compared with afterglowing signs made according to the prior art.

Another object of the present invention is to remedy the problem that certain colours and shades are not suitable for afterglowing signs according to the prior art, since they cannot give colour reproduction in daylight as clear and as sharp as in the dark, where, for example, red is one such colour. Summary of the Invention

The objects described above are achieved according to the present invention by means of an afterglowing sign comprising a sign material and afterglowing pigments, where a first layer of afterglowing pigments is applied to the sign material or where the afterglowing pigments are incorporated into the sign material, a second layer of fluorescent colour being applied on top of the first layer of afterglowing pigments or applied to the sign material where the afterglowing pigments are incorporated into the sign material. This means that the afterglowing pigments can be either inlaid in the sign material or be applied as a separate layer to the sign material, and that a layer of fluorescent colour is situated outermost on the sign. According to the present invention, the afterglowing pigments as such can be in various shades or colours.

When these signs are compared to signs as described above the af- terglowing signs according to the present invention clearly differentiate themselves with regard to colour reproduction in comparison with afterglowing signs according to the prior art.

When compared to signs according to SE 519 842, the signs according to the present invention do not include any screen print which can spoil re- production with certain colours and certain light, but instead, in the case of signs according to the present invention, any layer of afterglowing pigments is covered by an additional layer of fluorescent colour, that is to say what is conventionally called neon colours or daylight colours. This means that the signs according to the present invention give a completely different colour reproduction in daylight than the afterglowing signs according to SE 519 842. For the first point, according to SE 519 842, it is only one screen print which coats the afterglowing colour layer and since the afterglowing colours do not give particularly good colour reproduction in daylight such a sign with similar colour shades as an afterglowing sign according to the present invention can never be as distinct as a neon coloured sign according to the present invention. For the second point, screen printing may in certain cases cause spoiling of both colour reproduction and the overall reproduction when symbols, fig- ures and/or motifs are to be reproduced. Hence, under certain conditions it can be a big advantage not to produce signs by screen printing, for example signs in small format where the viewing distance is short. Incidentally, in such cases the screen can be seen as disturbing for the sign's observers. Such a problem is not found with afterglowing signs according to the present inven- tion, which means that an afterglowing sign according to the present invention is significantly more suitable in applications where text or motifs is/are to be reproduced on an afterglowing sign. This means that afterglowing signs according to the present invention are significantly more suitable for advertising or information signs than signs according to SE 519 842, since signs accord- ing to the present invention are seen very easily in daylight as they include fluorescent colours or neon colours. Furthermore, they are not made with screen printing, which in certain cases can be disturbing. Moreover, it is an advantage with the afterglowing signs according to the present invention that although the outermost layer has a very sharp and distinct colour, owing to the neon colours being used, this layer of fluorescent colour allows charging of the underlying layer with afterglowing pigments through the layer of fluorescent colour. This is something which is not possible with other types of conventional colours that may be considered for use on afterglowing signs for optimal daylight colour reproduction, as for example transparent colours which are liquid colours and formed in a different way from neon colours according to the present invention.

The afterglowing signs according to the present invention are also very different from the afterglowing signs according to SE 526 916. Signs according to SE 526 916 have a layer of afterglowing pigments located outermost in the sign. Naturally, as a result it is easy to intensify the afterglowing colour, but colour reproduction in daylight will not be as good since the afterglowing colours are not distinct. Even if the opaque colour under the layer of afterglowing pigments shines through the layer of afterglowing pigments, the col- our reproduction will not be distinct. This means also that certain colour types and combinations work significantly less well than others. The clear difference between afterglowing signs according to the present invention and signs according to SE 526 916 is that there is a layer of fluorescent colour located outermost in an afterglowing sign according to the present invention, so that a distinct and sharp colour is reproduced. As mentioned earlier this distinct and highly coloured layer still allows charging of the underlying layer of afterglowing pigments. In the case of afterglowing signs according to SE 526 916, the layer of afterglowing pigments is located uppermost, with the result that the reproduction is not as distinct as far as the colours are concerned. In addition, as mentioned, there are colour combinations which cannot be used because the reproduction of the sign will not be optimal, which is not the case with the neon colours according to the present invention where the layer containing these colours is located outermost on the sign. In summary, in afterglowing signs according to the present invention colour reproduction is very distinct, which is due to the location of a layer of fluorescent colour outermost on the sign. Notwithstanding that this clear colour is reproduced in daylight, these neon colours according to the present invention mean that charging of the afterglowing pigments, normally located as a layer under the layer of the fluorescent colour, can be achieved, which means that colour reproduction can also be made optimal in the dark. It is not possible to lay an opaque colour instead of fluorescent colour as the outermost layer since charging and transparency of the underlying layer of afterglowing pigments is then not possible in the dark. Since the fluorescent col- ours according to the present invention are transparent it is therefore possible to obtain charging and afterglowing of the underlying layer of afterglowing pigments through the outermost located layer, that is to say the second layer of fluorescent colour. The same applies when the afterglowing pigments are incorporated into the sign material. It has not been possible to obtain this combination of advantageous properties with afterglowing signs according to the prior art, as described above, which also means that afterglowing signs according to the present invention are advantageous when used, for example, as advertising signs because they give sharper and more distinctive colour reproduction in daylight. In addition, there are no problems with copious text or several motifs in a sign according to the present invention. This can be a problem with, for example, afterglowing signs according to the prior art which include screen printing.

With afterglowing signs according to the present invention it is possible to obtain signs which show sharp and distinct colours in daylight, but which can still show clear colour in the dark. This applies equally to any form of motif, symbol and/or text introduced into the afterglowing sign, which motifs, symbols and/or text is/are to be displayed in daylight as well as in the dark. Brief Description of the Drawings

Figure 1 shows an exploded view of an afterglowing sign according to the present invention comprising a sign material, where a first layer of afterglowing pigments is applied on top of the sign material, and where a second layer of fluorescent colour is applied to the first layer of afterglowing pigments.

Figure 2 shows an exploded view of an afterglowing sign according to the present invention comprising a layer as above, where the second layer of fluorescent colour contains a motif in the form of a text and a border which is located outermost round the whole sign, while the first layer of afterglowing pigments does not include a motif but only has an afterglowing colour which covers the whole of this first layer. Figure 2 shows in this case an advertising or information sign according to the present invention.

Figure 3 shows an exploded view of an afterglowing sign according to the present invention comprising the layers according to figure 1 , where the first layer of afterglowing pigments has a motif which is in line with the motif arranged on the second layer of fluorescent colour. Figure 3 shows an example of a safety sign according to the present invention.

Figure 4 shows an exploded view of an afterglowing sign according to the present invention comprising the layers according to figure 1 , where a cut- out is arranged in the second layer of fluorescent colour, which cut-out tallies with the motif which is arranged on the first layer of afterglowing pigments. Figure 4 shows in this case a safety sign according to the invention. Figure 5 shows an exploded view of the two layers as presented in figure 4, but where a recessed outline is arranged round the motif on the first layer of afterglowing pigments.

Figure 6 shows an exploded view of an afterglowing sign according to the present invention comprising the layers according to figure 1 , where a motif in the form of text is arranged on the first layer of afterglowing pigments and a second motif in the form of another text is arranged on the second layer of fluorescent colour, where the motif in the second and first layers do not overlap each other. Figure 6 shows an example of an advertising or informa- tion sign according to the invention.

Detailed Description of Specific Embodiments

To increase understanding of the present invention where, for example, this is exemplified together with the drawings, especially important definitions are clarified below. Definitions

Safety sign: a sign which warns against health and accident risks, e.g. for the identification and display of escape routes and emergency exits as well as the marking of the location of, for example, fire-fighting equipment. These signs can also show other possible dangers, such as fire risk etc. Signs that mark where certain chemicals and the like can be encountered in diverse industries ought also to be included in this group of signs. Safety signs are divided into several categories, namely prohibition signs, compulsory signs, warning signs, signs for emergencies, such as for example showing an emergency exit, and finally signs for fire, such as showing fire risk or location of fire-fighting equipment.

Advertising or information sign: in principle a sign which conveys a commercial message or information, the latter, for instance, at an airport or similar public places, which means that safety signs as described above are excluded. The term "sign material" refers to the material which forms the base material of the sign. As indicated above, the afterglowing pigments can be integrated into this sign material or a first layer which includes the afterglowing pigments can be applied to the sign material. The term "the principal colour", which term is used for the description of certain specific embodiments of the invention, refers to the main colour of the layer concerned. The term is used because it is fairly self-evident that motifs, such as text, figures etc, normally have a colour other than the base colour of the layer concerned. This base colour is normally called "the principal colour". When it applies to safety signs, this principal colour is called the safety colour.

Screen printing: one of the many printing methods in the graphics industry. Screen printing is characterised principally in that it is the only printing method where one can adjust and control the printed colour quantity in a way completely different from all the other printing methods. A typical colour layer thickness is 10-40 microns, but even up to more than 200 microns can be achieved. Other printing methods give about 2-5 microns. The printing procedure is based on the so-called through print method, that is to say the colour is pressed by means of a rubber squeegee through a stencil in the form of the desired motif. The stencil is held in a polyester weave with various mesh sizes. The mesh size of the weave is the most important factor determining the quantity of colour. The weave with the stencil is usually mounted in an aluminium frame. Screen printing can be carried out with everything from simple equipment for hand printing to very large automatic lines with up to 5 machines in succession with a line size about 2 x 4 meters.

Offset printing: a recognised term within the technical sector which generally refers to an indirect lithographic planography method, which means that the impression from a printing plate is first deposited on a rubberised cylinder and thereafter onto various materials. Transfer printing: a recognised term within the technical sector, which generally refers to the transfer of a completed motif by pressure.

The term "colours which correspond with each other" is to be understood as meaning two colours that are similar to each other or of a similar shade. Examples of this could be green and light green, red and light red etc., that is to say a colour and a lighter or darker tone of the same colour. Other examples could be blue and mauve or the combination light red and orange. The invention is further described below by specific working examples, which in certain cases are to be read in conjunction with and based on the accompanying drawings. These drawings are also described in more detail below.

According to a specific embodiment, the present invention is an after- glowing sign which comprises a sign material and afterglowing pigments, where in addition the second layer of fluorescent colour has enhanced afterglow by the fluorescent colour being mixed with afterglowing pigments. This can be realised in certain cases where it is appropriate to blend certain fluorescent colours with afterglowing pigments in the outermost layer. Naturally, in this case certain combinations of colour of the afterglowing pigments and fluorescent colour can be better than others.

According to another specific embodiment, the present invention is an afterglowing sign comprising a sign material and afterglowing pigments, where a second layer of fluorescent colour, which has enhanced afterglow by the fluorescent colour being mixed with afterglowing pigments, is applied di- rectly to the sign material. This means that there is only one layer that is applied to the sign material, this layer including fluorescent colour as well as afterglowing pigments. Similarly this embodiment can be realised for certain colours which are suitable for blending with afterglowing colours or pigments in one and the same mixture. This mixture is then applied as a single layer to the sign material. Also in this case, certain combinations of colour of the afterglowing pigments and fluorescent colour can naturally be better than others. This specific embodiment is not shown in the figures.

Further, according to another specific embodiment, the present invention is an afterglowing sign which comprises a sign material and afterglowing pigments, where a first layer of afterglowing pigments is applied to the sign material or where the afterglowing pigments are incorporated into the sign material, a second layer of fluorescent colour being applied on top of the first layer of afterglowing pigments or applied to the sign material when the afterglowing pigments are incorporated into the sign material, and the first layer of afterglowing pigments and/or the second layer of fluorescent colour being applied by means of screen printing, offset printing or transfer printing or a combination of these. According to another specific embodiment of the invention, the thickness of the first layer of afterglowing pigments and/or the thickness of the second layer of the fluorescent colour is/are less than or equal to 50 μm. The thickness of the layer and pigment density or concentration of colour is sig- nificant for colour reproduction, especially in the dark. Too thick a second layer of fluorescent colour means that there is increased risk that the charging of the underlayer of the afterglowing pigments is not as effective, since it is harder for the light to penetrate through the second layer of fluorescent colour. It is not only the charging which is affected negatively by an excessively thick layer, but also reproduction. It has been found by experiment, and when these experiments included a red neon colour with a pigment concentration of about 30 %, that when the thickness of the second layer of the fluorescent colour exceeded 50 μm the afterglow of the underlying first layer of afterglowing pigments did not work optimally. As mentioned, it is the pigment concentration or density in the fluorescent colour which determines how thick this layer can be without an excessive thickness such that the light cannot penetrate through and such that the afterglow layer cannot be charged and the reproduction of this afterglowing layer becomes too faint. This means that the thickness which is stated in the present invention is to be read on the understanding that these values are relevant for a pigment concentration of about 30 % in the fluorescent colour layer. Should this concentration be reduced somewhat the possible thickness can even be increased since the two are in principle proportional. In other words, a reduction in pigment concentration from about 30 % to about 20 % should mean that the thickness of the fluorescent colour layer possible could be increased from about 50 μm to about 75 μm.

A further parameter which is of significance in this connection is the composition of the fluorescent colour which is intended to be used. A whole group of such colours contain solvents, which to a large extent evaporate off during or in connection with the printing of such colours. This means that the pigment concentration in such a colour can be lower before printing than afterwards. The thickness of the first layer of afterglowing pigments, when such a layer is applied to the sign material, is also of significance. Nothing has been found to indicate that the afterglow becomes stronger and the charging works better the thicker this layer is, but it has been observed that this first layer of afterglowing pigments is more effective up to a certain thickness. This is because there are more particles of afterglowing pigment for the light to meet and excite in daylight than when too sparse a layer is used. In other words, it seems as if an increased effect can be obtained up to a certain thickness, about 50 μm. Thereafter the improved effects become insignificant. The costs are naturally also of importance. The thicker the layers are the more material is used, which means a more expensive sign. This inherently favours keeping down the thickness of the layers, so long as the colour reproduction works as well as expected in daylight and dark. According to a specific embodiment of the invention, the thickness of the first layer of after- glowing pigments and/or the thickness of the second layer of fluorescent colour is/are in the range 10-20 μm. Tests with the red neon colour referred to have shown that these thicknesses work very well in achieving distinct and sharp colours in daylight, which is due to the red neon colour in the second layer of fluorescent colour, and also a clear red afterglow in the dark, which is due to the red afterglowing pigment in the first layer.

As indicated it can be of interest to keep down the thickness of the second layer of fluorescent colour relative to the first layer of afterglowing pigments. In this way the charging effect can be raised, which thereby can also give improved afterglow. Therefore, according to a specific embodiment of the present invention, the thickness of the first layer of afterglowing pigments is greater than or the same as the thickness of the second layer of fluorescent colour. Further, the distinct and sharp colour reproduction of the second layer of fluorescent colour can be kept high even if the layer is not especially thick, for example in the range 10-20 μm. However, which colour is used, or what colour combination of the first layer, if any, and the second layer, may be significant for the optimal thickness of both layers relative to each other. Afterglowing signs according to the present invention can be used as safety signs as well as, for example, advertising signs. In either case, it is of interest to produce these signs in such a way that they reproduce anything which is to be shown to an observer, for example a motif or a text. Since col- our reproduction is of great significance, it is natural that the mentioned motif or text has a colour which is sharp relative to the colour or colours as shown in the rest of the sign. According to an embodiment of the invention, the after- glowing sign therefore comprises at least one motif, one symbol, one figure, one text or one combination thereof which is arranged on the first layer of af- terglowing pigments, the second layer of fluorescent colour or a combination thereof and which has at least one colour other than the principal colour of the second layer of fluorescent colour.

Symbols, text, figures or motifs can be incorporated into the sign in various ways. Symbols, text, figures and motifs can be printed by conven- tional means by usual printing methods, such as screen printing as described herein. As mentioned earlier, it has been found that there are a number of factors which are important to take into account when it is of interest to create symbols, motifs and/or text in an afterglowing sign according to the present invention, where these symbols, motifs and/or text and their colours as well as the principal colour of the sign are to be as sharp in daylight as in the dark. An important aspect is the colour laid outermost from the sign material, that is to say the fluorescent colour according to the present invention. It is essential that the sign does not have any opaque colour which is located outermost, if this part is not to be black in the dark. The fluorescent colours according to the present invention are not opaque, with the result that charging of the underlying layer of afterglowing pigments is possible. This means also that afterglow of the first layer of afterglowing pigments can penetrate through the layer of fluorescent colour, unless this second layer is too thick. However, since colour reproduction in daylight as well as in the dark is of interest many different colours and types of layer are found which can be applied in combination with each other, but the charging and the light transmission possible through the layer of afterglowing pigments must be sufficient to be able to achieve the desired colour reproduction in the dark. Consequently, this also means that there can be no opaque colour over the first layer of afterglowing pigments, since charging and light transfer by the afterglowing layer is not then possible. Should however a dark colour be the one to be shown in the dark for just one section naturally such a solution could still be possible, but not for any other colours. What this means of course is that if other opaque colours are used outermost these will be perceived as completely black in the dark.

According to a specific embodiment of the present invention, at least one motif, one symbol, one figure, one text or one combination thereof is ap- plied as at least one more layer of fluorescent colour on top of the second layer of fluorescent colour.

According to one embodiment, said one more layer of fluorescent colour on top of the second layer of fluorescent colour has a thickness which is less than or equal to 20 μm. According to another specific embodiment of the invention, said at least one motif, one symbol, one figure, one text or one combination thereof corresponds with at least one cut-out with the same shape as said at least one motif, one symbol, one figure, one text or one combination thereof, which said cut-out is arranged in the second layer of fluorescent colour. According to a further embodiment, at least one colour layer of fluorescent colour, which forms said at least one motif, one symbol, one figure, one text or one combination thereof, is applied directly into said at least one cutout on top of the first layer of afterglowing pigments.

In accordance with yet another embodiment of the present invention, said at least one motif, one symbol, one figure, one text or one combination thereof is arranged in the first layer of afterglowing pigments, where at least one other motif, one symbol, one figure, one text or one combination thereof, which is arranged in the second layer of fluorescent colour, corresponds with said at least one motif, one symbol, one figure, one text or one combination thereof in the first layer of afterglowing pigments.

The colour composition of the various layers and how these relate to each other is of significance for afterglowing signs according to the present invention. It is quite natural that certain combinations work better than others. A logical embodiment of the present invention includes an afterglowing layer where the principal colour of the first layer of afterglowing pigments and the principal colour of the second layer of fluorescent colour are in keeping with each other. This is as a matter of course an afterglowing base sign according to the present invention, but there are many other signs according to the invention which can also be imagined where these layers do not have the same colour.

According to another specific embodiment of the present invention, the principal colour of the sign material under the first layer of afterglowing pig- ments is of the same shade or colour or a lighter shade or colour as the principal colour of the first layer of afterglowing pigments.

It is clear that there are many colours which it is possible to imagine being applied. As far as the afterglowing pigments are concerned certain colours work better than others, but in principle most are feasible. For safety signs as used today the colours red, blue, green, white, yellow and black and of course combinations thereof are common. For afterglowing safety signs according to the present invention it is therefore logical to use these colours on the first layer of afterglowing pigments. According to a specific embodiment of the invention the afterglowing pigments are therefore white/yellowish- white, yellow, red, blue and/or green.

The base sign itself, that is to say the sign material without the first layer of afterglowing pigments and without the second layer of fluorescent colour, can for example be made of metal, plastic or composites.

As mentioned earlier the afterglowing pigments can be incorporated into the sign material, instead of being incorporated in a layer which is applied on top of the sign material. In this case, the sign material cannot be made totally of metal. On the other hand for example it is possible to have the afterglowing pigment incorporated into a sign material of afterglowing foil or plastic. In this case, it is also possible, for example, that an additional transparent layer is applied between the sign material and the fluorescent outermost colour layer. This transparent layer could also be thought of as an additional layer between a first layer of afterglowing pigments and a second layer of fluorescent colour. It can be of interest to enhance the reproduction of symbols, text or motifs. This can be achieved by application of a recessed outline round certain shapes. According to a specific embodiment of the present invention, at least one recessed outline is therefore arranged round said at least one motif, one symbol, one figure, one text or one combination thereof in the first layer of afterglowing pigments.

Naturally, as mentioned earlier, the colours that are used are significant. This applies as a matter of course also to the second layer of fluorescent colour. An advantage with an afterglowing sign according to the present invention is that by application of these neon colours a larger colour choice is available than with afterglowing signs according to the prior art, where only certain afterglowing colours work for good reproduction in daylight. However, certain colours are employed more than others among neon colours. According to a specific embodiment of the invention, the second layer of fluorescent colour has therefore at least one fluorescent colour which has been chosen from the group consisting of a typical neon colour which has at least a shade of yellow, orange, green, red, blue, mauve or rose.

With regard to the composition of these fluorescent or neon colours, there are also specific embodiments of the present invention. According to one embodiment, the colour of the second layer of fluorescent colour contains at least one unsaturated acrylate resin. According to a second embodiment, the colour of the second layer of fluorescent colour contains at least one unsaturated acrylate resin and at least one vinylcaprolactam. According to a very specific embodiment of the present invention, the colour of the second layer of fluorescent colour contains in addition at least one unsaturated acrylate resin in a quantity in the range 60-65 weight%, at least one vinylcaprolactam in a quantity in the range 5-10 weight%, 2-benzyl-2-dimethylamino-4- morpholino butyrophenone in a quantity in the range 1-5 weight% and 2- hydroxy-2-methyl-1-phenyl-1-propanone in a quantity in the range 0.1-1 weight%.

Finally, the present invention also includes the use of an afterglowing sign according to the invention as a safety sign, advertising sign or information sign. Detailed Description of the Drawings and Various Embodiments herein

Figure 1 shows an exploded view of an afterglowing sign according to the present invention. A first layer 2 of afterglowing pigments is applied to the sign material 1. A second layer 3 of fluorescent colour 4 is applied on top of this first layer 2 of afterglowing pigments. The fluorescent colour 4 gives a distinct colour reproduction by day, while the first layer 2 of afterglowing pigments is the layer 2 that is visible to an observer at night. According to figure 1 these layers are only colour layers, that is to say including no motifs. One can of course consider all possible combinations in this case, that is to say that one of the layers in addition has a motif or that both layers have one. Various colour combinations for the two layers are variously suitable with a view to achieving a good colour reproduction effect both in daylight and in the dark.

It is important to understand that it is also quite possible for the after- glowing pigments to be incorporated with or integrated into the sign material 1 and for the second layer 3 of fluorescent colour 4 to be applied directly to the sign material 1. This applies primarily for the embodiments where there is not a very complicated motif which is to be reproduced in the dark, that is to say from the afterglowing pigments, but perhaps only one colour, for example. Moreover, it is quite possible for an additional transparent layer to be provided in the assembly, for example directly on top of the sign material 1 in the cases where the afterglowing pigments are integrated therein or between a first layer 2 of afterglowing pigments and a second layer 3 of fluorescent colour 4. Figure 2 shows an exploded view of an afterglowing sign according to the present invention comprising a sign material 1 to which a first layer 2 of afterglowing pigments is applied. A second layer 3 which has a fluorescent principal colour 4 is applied on top of this first layer 2 of afterglowing pigments. This second layer 3 which has a fluorescent principal colour 4 has two motifs 5, which in this case are the text "MESSAGE Day" and the border which surrounds the whole of this second layer 3. The first layer 2 of afterglowing pigments has a principal colour 7. Naturally, this layer can also include different motifs and examples of this are given in figures 3-6. Figure 2 represents one example of an advertising or information sign according to the present invention.

Figure 3 shows an exploded view of an afterglowing sign according to the present invention comprising a sign material 1 to which a first layer 2 of afterglowing pigments is applied. A second layer 3 which has a fluorescent principal colour 4 is applied on top of this first layer 2 of afterglowing pigments. This second layer 3 which has a fluorescent principal colour 4 includes motif 5, which in this case consist of motifs for a typical safety sign, in this case an escape sign which shows an emergency exit. The first layer 2 of af- terglowing pigments has a principal colour 7 and motifs 5 which coincide with the motifs 5 on the second layer 3. With a sign such as this it is natural that it is desirable that the same motifs 5 and colours 7 and 4 shall be seen in daylight as well as in the dark, since the sign indicates an escape route, and therefore it is appropriate that similar colours or shades are used for the mo- tifs and the background or base colour of both layers. A specific example for such an escape route sign is where the first layer 2 of afterglowing pigments has a principal colour 7 which is a green afterglowing colour and where the motifs 5 of this layer include a white afterglowing colour, while the second layer 3 of fluorescent colour 4 for its part has a principal colour 4 which is a green neon colour and where the motifs 5 include a white neon colour. In this way an effective colour and motif reproduction can be obtained in daylight as well as in the dark. Figure 3 represents one example of a typical safety sign according to the invention.

It should be understood that various possibilities exist for printing the motifs in both layers. The layer is printed either as a whole or the background is printed first and the motif thereafter on the actual layer. This means that it is possible to use completely conventional methods for printing of motifs on a sign according to the present invention.

Figure 4 also shows an exploded view of an afterglowing sign accord- ing to the present invention, comprising a sign material 1 to which a first layer 2 of afterglowing pigments is applied. A second layer 3 which has a fluorescent principal colour 4 is applied on top of this first layer 2 of afterglowing pigments. This second layer 3 which has a fluorescent principal colour 4 has cut-outs 6, which in this case correspond to the motifs 5 for a typical safety sign, in this case an escape route sign. The first layer 2 of afterg lowing pigments has a principal colour 7 and motifs 5 which correspond with the cutouts 6 on the second layer 3. With a sign such as this, naturally what is de- sired is that the same motifs 5 and colours 7 and 4 shall be seen in daylight as well as in the dark, since the sign indicates an escape route. Therefore it is appropriate that similar colours or shades are used for the principal colours 4 and 7 in both the layers. However, in this case it is the white afterglowing colour which forms the motifs 5 in the first layer 2 of afterglowing pigments which is also seen through the cut-outs 6 in the second layer 3 in daylight. Which of the embodiments illustrated with cut-outs 6, that is to say according to figure 4, and without cut-outs 6 (figure 3), is best to use depends on several different parameters, such as for example which colour combinations it is desired to use and what motifs 5 are to be shown. Figure 4 thus represents an exam- pie of a typical safety sign according to the invention.

With a sign according to figure 4 including cut-outs 6 an afterglowing sign according to figure 3 can also be obtained, made for example by printing, at the very end, a white neon colour in the cut-outs 6 over the white afterglowing colour in the first layer 2. Figure 5 shows an exploded view of the two layers as represented in figure 4, but where a recessed outline 8 is arranged round the motif 5 on the first layer 2 of afterglowing pigments. This recessed outline 8 can ensure that the contours of the motif 5 are clearly visible in the dark through the corresponding cut-out 6 in the second layer 3. Figure 6 shows an exploded view of an afterglowing sign according to the present invention including the layers according to figure 1 , in which a motif 5 in the form of text ("MESSAGE Night") is arranged on the first layer 2 of afterglowing pigments and a second motif 5, in the form of a second text ("MESSAGE Night") is arranged on the second layer 3 of fluorescent colour 4, where the motifs 5 in the first and second layers do not overlap each other. What it is possible to achieve with advertising and information signs such as these depends very much on what is to be displayed in the dark and which colour combinations one wishes to employ. There are possible combinations where differing motifs can overlap each other, but then the colour compositions must be right. Naturally it is not only the colour of the motifs which is of interest, but also the colour 7 of the first layer 2 of afterglowing pigments relative to the fluorescent colour 4 on the second layer 3 is significant.

Claims

1. An afterglowing sign comprising a sign material (1) and afterglowing pigments, where a first layer (2) of afterglowing pigments is applied to the sign material (1) or where the afterglowing pigments are incorporated into the sign material (1), a second layer (3) of fluorescent colour (4) being applied on top of the first layer (2) of afterglowing pigments or applied on top of the sign material (1) when the afterglowing pigments are incorporated into the sign material (1).

2. An afterglowing sign according to claim 1 , wherein the second layer

(3) of fluorescent colour (4) further has enhanced afterglow by the fluorescent colour being mixed with afterglowing pigments.

3. An afterglowing sign comprising a sign material (1) and afterglowing pigments, wherein a second layer (3) of fluorescent colour (4), which has en- hanced afterglow by the fluorescent colour (4) being mixed with afterglowing pigments, is applied directly to the sign material (1).

4. An afterglowing sign according to any one of claims 1-3, wherein the first layer (2) of afterglowing pigments and/or the second layer (3) of fluorescent colour (4) is/are applied by means of screen printing, offset printing or transfer printing or a combination thereof.

5. An afterglowing sign according to any one of claims 1-4, wherein the thickness of the first layer (2) of afterglowing pigments and/or the thickness of the second layer (3) of fluorescent colour (4) is/are less than or equal to 50 μm.

6. An afterglowing sign according to any one of claims 1-5, wherein the thickness of the first layer (2) of afterglowing pigments and/or the thickness of the second layer (3) of fluorescent colour (4) is/are in the range 10-20 μm.

7. An afterglowing sign according to any one of claims 1-6, wherein the thickness of the first layer (2) of afterglowing pigments is greater than or equal to the thickness of the second layer (3) of fluorescent colour (4).

8. An afterglowing sign according to any one of claims 1-7, wherein the afterglowing sign comprises at least one motif, one symbol, one figure, one text or one combination thereof (5) which is arranged on the first layer (2) of afterglowing pigments, the second layer (3) of fluorescent colour or a combination thereof and which has at least one colour other than the principal colour (4) of the second layer of fluorescent colour (4).

9. An afterglowing sign according to claim 8, wherein said at least one motif, one symbol, one figure, one text or one combination thereof (5) is applied as at least one more layer of fluorescent colour on top of the second layer (3) of fluorescent colour (4).

10. An afterglowing sign according to claim 9, wherein said one more layer of fluorescent colour on top of the second layer (3) of fluorescent colour (4) has a thickness which is less than or equal to 20 μm.

11. An afterglowing sign according to claim 8, wherein said at least one motif, one symbol, one figure, one text or one combination thereof (5) corresponds with at least one cut-out (6) with the same shape as said at least one motif, one symbol, one figure, one text or one combination thereof (5), which cut-out (6) is arranged in the second layer (3) of fluorescent colour (4).

12. An afterglowing sign according to claim 11 , wherein at least one colour layer of fluorescent colour, which forms said at least one motif, one symbol, one figure, one text or one combination thereof (5) is applied directly in said at least one cut-out (6) over the first layer (2) of afterglowing pigments.

13. An afterglowing sign according to claim 11 , wherein said at least one motif, one symbol, one figure, one text or one combination thereof (5) is arranged in the first layer (2) of afterglowing pigments and wherein at least a second motif, symbol, figure, text or combination thereof (5) which is arranged in the second layer (3) of fluorescent colour (4) corresponds with said at least one motif, one symbol, one figure, one text or one combination thereof (5) in the first layer (2) of afterglowing pigments.

14. An afterglowing sign according to any one of the previous claims, wherein the principal colour (7) of the first layer (2) of afterglowing pigments and the principal colour (4) of the second layer (3) of fluorescent colour (4) correspond with each other.

15. An afterglowing sign according to any one of the previous claims, wherein the principal colour of the sign material (1) under the first layer (2) of afterglowing pigments is of the same shade or colour or a lighter shade or colour as the principal colour (7) of the first layer (2) of afterglowing pigments.

16. An afterglowing sign according to any one of the previous claims, wherein the afterglowing pigments are white/yellowish white, yellow, red, blue and/or green.

17. An afterglowing sign according to any of the previous claims, wherein the sign material (1) is made of metal, plastic or composites.

18. An afterglowing sign according to any one of the previous claims, wherein at least one recessed outline (8) is arranged round said at least one motif, one symbol, one figure, one text or one combination thereof (5) in the first layer (2) of afterglowing pigments.

19. An afterglowing sign according to any one of the previous claims, wherein the second layer (3) of fluorescent colour (4) has at least one fluorescent colour (4) chosen from the group consisting of a typical neon colour which has at least a shade of yellow, orange, green, red, blue, mauve or rose.

20. An afterglowing sign according to any one of the previous claims, wherein the colour (4) of the second layer (3) of fluorescent colour (4) includes at least one unsaturated acrylate resin.

21. An afterglowing sign according to any one of the previous claims, wherein the colour (4) of the second layer (3) of fluorescent colour (4) includes at least one unsaturated acrylate resin and at least one vinyl caprolac- tam.

22. An afterglowing sign according to any one of the previous claims, wherein the colour (4) of the second layer (3) of fluorescent colour (4) in- eludes at least one unsaturated acrylate resin in a quantity in the range 60-65 weight%, at least one vinyl caprolactam in a quantity in the range 5-10 weight%, 2-benzyl-2-dimethylamino-4-morpholino butyrophenone in a quantity in the range 1-5 weight% and 2-hydroxy-2-methyl-1-phenyl-1-propanone in a quantity in the range 0.1-1 weight%.

23. The use of an afterglowing sign according to any one of claims 1-

22 as a safety sign.

24. The use of an afterglowing sign according to any one of claims 1- 22 as an advertising or information sign.