GB2497355A

GB2497355A - Luminescent gel coating and application to safety panels

Info

Publication number: GB2497355A
Application number: GB1121203.2A
Authority: GB
Inventors: Timothy Peter Hunter; Mark Anthony Roe
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-12-09
Filing date: 2011-12-09
Publication date: 2013-06-12
Also published as: GB2497386A; WO2013084006A1; GB2497385A; GB201218597D0; GB201218553D0; GB201121203D0

Abstract

A gel coating comprises a pigment and a photoluminescent element. Also shown is a safety access panel e.g. door, comprising a substrate and a gel coating, said gel coating being attached to and covering at least a part of said panel and wherein the gel coating comprises a single layer comprising a pigment and a photoluminescent element. Further shown is a method of manufacturing a pigmented, photoluminescent gel coating comprising at the steps, in this sequence, of first mixing the pigment and the photoluminescent material to make a mixture and second introducing the mixture to a carrier. The pigment is preferably white e.g. titanium dioxide and the photoluminescent material may be copper sulphide or zinc sulfide.

Description

Luminescent coating and p$jctjgn to safety panS dofteJnvention The present invention relates to gel coatings. More specifically, the invention relates to photoluminescent synthetic polymer blends usefu as gel coatings. The invention also relates to safety access panels comprising the above gel coatings, the safety panels including specifically doors. The invention also relates to methods of manufacturing the gel coating.

i«=Sground and Priojsjl The provision of photoluminescent, thermoluminescent, and eLectrotuminescent polymer blends used for as gel coats and as mouldabie resins is well**known. Commonly, a phosphorescent pigment such as a zinc suiphide structure with substitution of the zinc and activation by various elemental activators (typically ZnS:Cu, but other elements beside copper including aluminium, silver, gold, manganese, gallium, indium, scandium, Lead, cerium, terbium, europium, gadolinium, samarium, praseodymium or other rare earth elements and halogens, may be used). This element is suspended for example in a thermosetting and saturated polyester, along with a filler and utilised to make gel coated articles, for example, moulded, cast and fibreglass reinforced plastic articles. V4)1

Phototuminescent materials are used in a variety of commercial applications including warning signs, nachiney marking. dk illumination, directional signs, marking the edge of steps, fire helmets, accident protection, protective clothing and sports equipment.

Commercially available sheets of phototuminescent material typicaLly comprise phosphorescent pigment in clear polyvinyl chloride, Other approaches are also utilised, usualLy involving thermoplastics or elastomeric and rubbey materials, An example of such photolurmnescent textiles in the form of flexible sheet materials can be found at US Patent Number 4211813 (GRAVISSE), Here the sheet material was coated with a thin film of photoluminescen.t synthetic resin containing a phosphorescent metal sulphide and a ic substance which absorbs energy of short wavelength and emits energy at wavelengths which lie within the absorption spectrum of the phosphorescent constituent, Similarly, US Patent Number 5692895 discloses luminescent orthodontic appliances wherein a preferred plastics material comprising polycarbonate, glass fibre re-enforcement and a luminescent pigment, itself preferably zinc sulfide doped with copper or zinc sulfide doped with copper and manganese.

US Patent Number 5698301 (YONETANI) discloses a phosphorescent pigment in a varnish prepared by dissolving a resin such as a polycarbonate and acfyLic resin, a polyvinyl chloride or a polyester in a solvent and printing onto a transparent or reflective layer, is disclosed. Similarly, Luminescent films are commonly used on, for example, road signs.

A problem with using phosphorescent, photoiurninescent pigments in polymer resins is the tendency of the phosphorescent pigment to settle during blending operations and storage, oarticularly the larger size particles. usually known luminescent polymers must be blended and utilised immediately, often with the aid of air equipment to keep the phosphorescent particles in suspension. This is also true of thermosetting laminating and casting resins, where typically the phosphorescent particle falls out of suspension and cannot be sprayed or conveniently worked, This is one reason that attempts to produce a gel coating comprising a spedlic colour have not been successfuL Instead, the universally followed practice in this field for making a coloured object phosphorescent is to apply a transparent gel coating to its already pigmented surface, to produce a glossy, photoluminescent transparent or translucent coating, through which the colour of the pigmented surface underneath can be seen.

No one has yet been successFul in comhinng a phosphorescent pigment and a standard coloured pigment in a suspension without leading to separation of the two types of pigment or more commonly the overwhelming or masking of one by the other. Typically, previously when a colour has been added, the photoluminescence has been masked. As o such, the only combination available at the time of wrfting is a clear gel with a photolumninescent pigment suspended in it.

Thus it is a first object of the invention amongst others to attempt to find solutions to this problem.

A particular application of the new gel coating is in the context of a safety paneL Safe' panels include doors and other hatchways, notably including emergency exits. A conventional means of displaying an emergency exit is to either attach an exit sign to the safety panel or to put a light above or adjacent it, The drawbacks of these are readily i apparent -a sign may detach itseLf from the door, or a Light may go out, perhaps due to a power cut caused by the same emergency, triggering the need For the utilisation of the emergency exit. One of the things that the present invention offers is a way of fashioning safety panels including emergency exit doors in such a way that they are coLoured, preferably brightly, and therefore are highly visible under dayUght, or similar artifidat conditions, and emit a photoluminescent gLow when it is darker.

Thus it is a second object of the invention amongst others to attempt to Find solutions to this problem.

Surmnarystthtinyention a first broad, independent aspect, the invention comprises a safety access panel comprising a substrate and a get coating, said gel coating being attached to and covering at jeast a part of said paneL wherein the gel coating comprises a single layer comprising a pigment and a photoluminescent element, This combination of a pigment and a photoluminescent element, their being combined in such a way that both the pigment and the photoluminescent elernerfl are visible, with the safety panel necessarily having a pigmented colour during daylight' condftions and a luminescent hue during night time' conditions, has not been achieved before. The invention therefore comprises that innovation. Having a gel coating of this sort which is both pigmented and photo-luminescent is advantageous, because it allows for the coating of objects with a gel coating which has both of those properties. where this has not been 6 possIble before.

This Innovation Is of particular use when combined with a safety access panel Because suchadoortiteraftyglowsinthedark.thepaneLwhichmayforexamptebeatypeof emergency exit or escape hatch. may therefore dearty be seen by the user and located to easily at times when the panel needs to be utilised, i.e. during an emergency exit scenario.

The concept of the safety access panel includes guides towards hatches doors as well as the hatches and doors themselves, and includes shirting, ceiling and watt paneLs.

The provision of a Luminescent safety panel of this sort usefully allows fo: the user to is dispense with other forms of safety alert, such as emergency exit signs and lights -the glowing door is in Itself noticeable enough to attract users to It In times of emergency.

From a practical point of view the provision of a white door is likely to provide a door that stands out from surroundings, therefore marking It out as an emergency exit even during thedaytlme.

A gel coating of the sort described by the claim Is most effective, in that the Luminescence F of the coating can be seen up to approximately 200 feet away.

26 Preferably, the pigment is white.

The white/luminescent combination has been shown to balance' particularly well, that is to say neither of the pigment nor the luminescent material overwhelms the othec a strong white colour Is shown In daylight conditions, and a strong luminescence is shown in so conditions of relative darkness.

More preferably, the white pigment is titanium dioxide.

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The use of titanium dioxide has been shown to be most effective at mixing with the Luminescent material, and as such provIdes the best batance, within a mixture, of white in daytime' conditions, and luminescent' In darkness.

PreferabLy, the safety access panel is a door.

A door is a commonly used type of safety panel and it is expected that a gel coated door would be particularly useful from the point of view of being the type which is most generally utilised.

Preferabty the panel comprises glass reinforced plastic A coated paneL of this composition is strong, durable and tends Itself to mass production.

Preferably, the phototurninescent effect provided by the gel-coating comprises a green glow.

The green glow is that which Is associated with emergency exits by the public and as such using a green glow is particularly advantageous from the point of view of the access panel beIng so recognised.

Preferably, the gel coating Is 500-1200 microns thick.

This range ci get coating thicknesses Is of sufficient thickness to hold both the coloured materiaL and the luminescent material within it Preferably, the gel coating comprises a pigment mixture comprising titanium dioxide and a phototuminescent element ao The combining of the pigment and the photoluminescent element in a pigment mixture and then introducing into the gel. coating provides the most effective means of combining pigment and the photoluminescent element such that neither overwhelms the other and both are able to function optimally.

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Preferably, the gel coating comprises the outermost Layer of the paneL This form of gel coating doubles as a protective layer for the safety panel.

s The method also comprises a safety access panel substantially as described herein with reference to and as illustrated by any combination of the text and/ or drawings.

in a second broad, independent aspect, the invention comprises a gel coating comprising a single layer, comprising a pigment and a photoluminescent element, The advantage of this configuration of features, in the context of a safety panel is discussed above.

Preferab, the pigment is white.

The advantage of this feature, in the context of a safety panel is discussed above.

Preferably, the white pigment is titanium dioxide.

PreFerably, the photoluminescent effect provided by the coating comprises a green glow.

The advantage of this feature, in the context of a safety panel, is discussed above.

Preferably, the white pgmerit mixture also comprises the photoluminescent element The advantage of this feature, in the context of a safety panel, is discussed above.

The invention also comprises a gel coating substantially as described herein with reference to and as illustrated by any combination of the text and/or drawings In a third broad, independent aspect, the invention comprises a method of manufacturing a pigmented, photoluminescent gel coating comprising at least the steps, in this sequence, of first mixing the pigment and the photolurninescent material to make a mixture and second introducing the mixture to a carrier.

This method provides the means of ensuring that both the coLour effect of the pigment and the photoluminescent effect of the phototurninescent element are effective in this mixture. By combining them prior to introduction into the carrier, this provides the most appropriate means of militating against the separation of the pigment and the photoluminescent element do not separate or fail to combine or otherwise arrange themselves so that one takes precedence or overwhelms the other, Preferably, the method comprises the further step of spraying a gel coating onto the surface of a mould.

Spraying provides a means of achieving a uniform thickness of gel coating layer, whilst also ensuring that both the pigment and the photoluminescent Layer are distributed correctly.

Preferably, the carrier comprises a monomer resin.

This is a particularly effective carrier.

The invention also comprises a method of manufacturing a pigmented, photoluminescent gel coating substantially as described hereir,with reference to and as illustrated by any combination of the text and/or drawings.

The Methad The method, in detail, comprises the foUoing steps: the user chooses a base colour which n the case of desiring a white colour finish would preferably be titanium dioxide but could also be another pigment derived from natural mineral products and ground rflo a powder or similarly prepared. Colours can often be a blend of several base colours; the pigment is mixed with the luminescent materiaL * The pigment either remains as a powder or is made Into a paste.

* The mixture of the ground pigment and the luminescent material is then introduced to a monomer, typically styrene.

* the pigment/monomer mix is then made into a Liquid; * this liquid is then added to the gel coat which may comprise an unsaturated polyester to resin with either lsophthaLk orthophthatic or isoneopentyglycol (NPG) properties or a vinylester or a combination of in various proportions * in use, this unsaturated polyester film Is the first part of a composite to be placed into a given mould, this necessarily being the case because the gel coat forms the outer layer of the given item, such as a safety paneb * the gel coat Is sprayed into the mould It is necessary that the gel coating be sprayed and not brushed in order than a properly mixed, homogeneous, uniform film is introduced into the mould; * the sprayed layer preferably has a thickness of 500-1200 microns; * the gel coat cures under a thermoset reaction upon the introduction of a catalyst between 1% to 3% by weight until the polyester reaches near saturation. A typical catalyst used is Methyl Ethyl Ketone Peroxide (MEKP).

* when a safety panel or other type of laminate is being manufactured other elements are then added, such as fibreglass and a sub-frame. Composite fibreglass doors are built up in a system of layers, and at Least some of the layers comprise unsaturated polyester resins.

Thus, a gel coat on its own or as ap$iS to an item such as a safety panel is provided which has a white colouring In the light and which glows luminescent green in the darkness.

The key step is the addition of the photoluminescent pigments at the start of the process during the pigment mixing stage. Thus the pigment mix comprises typically titanium dioxide and copper sulphide, added to a monomer resin carrier which Is then made into a Liquid form and/or a get form as per the method above. Although the use of titanium dioxide produces a white get coating, it is envisaged that mixing other pigments will produce coatings of other colours, notably red, blue and International orange.

A panel made by this method produces a panel where the length of time that it glows before the glow has diminished enough not to otter any practical use. The Length of service without a Suction in the glow rate Is currently 1 year, The pigment mixture comprises photoluminescent pigment and titanium dioxide mixture typically make up 5% to 15% by weight of the total get coat weight where the 18 photoluminescence makes up from 5% to 50% of the total pigment weight depending upon the strength and Longevity of the gLow required.

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