WO2007068028A1

WO2007068028A1 - Photoluminescent textile materials

Info

Publication number: WO2007068028A1
Application number: PCT/AU2006/001569
Authority: WO
Inventors: Graham John Stolz
Original assignee: The Specialty Group
Priority date: 2005-12-16
Filing date: 2006-10-23
Publication date: 2007-06-21

Abstract

A photoluminescent material including a textile substrate having a base side and a protective side, the base side having a coating containing a photoluminescent pigment, the textile substrate is translucent or transparent to permit the phosphorescent pigment to emit and absorb light through the textile substrate. The base coating includes a first layer and a second layer, the first layer forming a secure bond to the substrate and the second layer containing photoluminescent pigment.

Description

Photoluminescent textile materials

Field of the invention

The present invention relates to textile material or other flexible sheet material to which a phosphorescent coating has been applied.

Background of the invention

Textile materials having high visibility have traditionally been achieved through the use of bright dyes, including fluorescent dyes. However, the effectiveness of these bright dyes is reliant upon the immediate reflectance of visible light from an external source. The use of retro-reflective materials provides additional visibility at night, through the instantaneous reflection of external light sources, such as a car's headlight.

Textile materials having high visibility in the absence of an external light source have been limited to textiles coated with a phosphorescent coating. The phosphorescent coating absorbs visible light from an external source and is able to emit visible light in the dark after removal of the initiating (charging) light source, thus providing high visibility.

The phosphorescent coating is applied to the external surface of the textile for use in novelty tee-shirts, safety apparel and the like. However, the durability and functionality of the external surface of the textile are often compromised by the phosphorescent coating. In particular, the coating is susceptible to abrasions and scuffing which lowers its aesthetic appeal in addition to reducing its effectiveness. As a result, the current use of phosphorescent textiles has not reached its full potential. The present invention is directed at solving the abovementioned deficiencies of photoluminescent textiles through improving the durability of the textile material. Summary of the invention

The present invention provides a photoluminescent material including a textile substrate having a base side and a protective side. The base side has a coating containing photoluminescent pigments, wherein the textile substrate is translucent or transparent to permit the phosphorescent pigment to emit and absorb light through the textile substrate.

An advantage of this photoluminescent material is that it uses the mechanical properties of the textile substrate to protect the phosphorescent coating from mechanical damage, thus increasing its durability. The protective side may also have a coating layer which enhances the material's resistance to the external environment, eg. water, soil and oil repellent.

An additiona[ protective layer may be added to the external surface of the photoluminescent base coating to provide further protection from wear on the base side of the textile, and to reduce changes in phosphorescent performance through contrast changes in underclothing, by an increase in the overall opacity of the article. The additional protective layer also serves to enable garment seam-sealing, through its permanent, thermoplastic nature.

The substrate material preferably transmits at least 40% of visible light, more preferably at least 60% of visible light, and even more preferably at least 75% of visible light. To maximise the translucent properties of the textile, without compromising its mechanical strength, the textile is preferably produced from a translucent material (eg. polyester fibre produced from translucent polyester resin).

The base coating preferably includes at least one layer having the photoluminescent pigments dispersed in a synthetic prepolymer resin or prepolymer. The synthetic prepolymer resin is preferably selected from the group consisting of polyurethane resins, polyvinyl chloride base resins, polyacrylate resins and elastomeric silicone resins. The base coating preferably includes up to 60% (w/w) photoluminescent pigment, with the photoluminescent pigment preferably being at least 25% (w/w) of the mass of the photoluminescent textile material.

The final base coat layer may include titanium dioxide pigments which act as an opaque barrier which facilitates the internal reflection of light onto the photoluminescent pigments and the reflectance of emitted light from the photoluminescent pigments through the transparent or translucent textile substrate.

The textile material preferably has a low resistance to water vapour transfer, with the water vapour transfer preferably being less than 60 m².Pa/W. This enables the textile to breathe and thus be suitable for use as a garment, baggage and outdoor equipment (eg. tents).

In another aspect of the present invention there is provided a photoluminescent material including:

a textile substrate having a base side and a protective side, the base side having a coating containing a photoluminescent pigment, the textile substrate being translucent or transparent to permit the phosphorescent pigment to emit and absorb light through the textile substrate,

wherein the base coating includes a first and a second layer, the first layer forming a secure bond to the substrate and the second layer containing photoluminescent pigment.

Preferably, the viscosity of the first layer, as it is applied to the substrate, is sufficiently high to prevent penetration of the first layer and subsequent layer(s) (i.e. the base coating) into the textile substrate. In contrast, the viscosity of the second layer is preferably sufficiently low to ensure an even distribution of photoluminescent pigment across the substrate.

To achieve these functional requirements, the first layer preferably has a viscosity greater than the second layer. Preferably, the base coating further includes at least one more layer, containing photoluminescent pigment.

Each base coat layer preferably contains a prepolymer, such that the base coating may be cured to form an integral coating, which is resilient and durable to the wear and tear of demanding applications. Further, the use of successive coating layers containing photoluminescent pigment enables high photoluminescent pigment concentrations to be achieved which deliver desirable functional properties.

The base containing layers (which contain photoluminescent pigment) are typically added onto the substrate at a rate of 50 to 120 grams per square metre on a non- volatile basis. The non-volatile component of the first layer is preferably applied at a rate of 15 to 25 grams per square metre, which may, or may not contain photoluminescent pigment.

The secure bonding of the base coating to the substrate provides resistance against the base coating detaching from the substrate.

In a third aspect of the present invention, there is provided a method for producing a photoluminescent material including the steps of:

applying a base coating containing photoluminescent pigment to a base side of a textile substrate; the textile substrate is translucent or transparent to permit the phosphorescent pigment to emit and absorb light through the textile substrate,

the application of the base coating includes the steps of (i) applying a first layer, which forms a secure bond to the substrate, (ii) applying a second layer containing photoluminescent pigment.

The viscosity of the first layer may be adjusted to prevent penetration of the first layer and subsequent layer(s) into the substrate. The first layer preferably includes a prepolymer, a solvent and a crosslinking additive. Although it is conceivable that a crosslinking additive may not be required for prepolymers which self polymerise under specific conditions. The solvent level of the first layer is adjusted to maximise the viscosity of the layer, such that the coating does not penetrate the textile substrate. The crosslinking additive crosslinks the prepolymer to cause further polymerisation, thereby hardening the layer. The activation of the cross-linking additive and the prepolymer may be accelerated by use of elevated temperatures, UV light and/or the addition of a crosslinking catalyst.

The second layer preferably includes a prepolymer, a solvent and a crosslinking additive. The solvent level of the second layer is adjusted to ensure an even distribution of photoluminescent pigment across the substrate. A surfactant may also be added to facilitate an even flow of material across the preceding coating layer.

To achieve the desired concentration of photoluminescent pigment, further layers, having similar composition to the second layer, may be applied.

To enhance, the emission of light from the first side of the substrate to the second side, a finishing layer is preferably applied to the last of the photoluminescent pigment layers. The finishing layer preferably includes a prepolymer, a solvent, titanium dioxide and a crosslinking additive.

Preferably, each layer of the base coating is dried to remove the solvent before the next layer is applied. The layers are preferably dried between 8O⁰C to 13O⁰C, with the temperature being sufficiently high to evaporate off the solvent, but not high enough to activate crosslinking of the prepolymer. After drying of the final layer in the base coating, the base coating is preferably cured at an elevated temperature (typically between 16O⁰C and 180°C, the curing process promoting an integral crosslinked base coating.

In the crosslinking process, the first layer forms a secure bond with the textile substrate. The first side of the textile substrate may also be pre-treated to enhance the strength of the bond to the first layer. Pre-treatment may be in the form of the application of a bonding layer which securely links the substrate to the first layer. Alternatively, the surface of the substrate may be chemically or otherwise treated (eg. corona discharge) to enhance the ability of the substrate to bond with the first layer.

The method preferably further includes the step of applying a protective coating (water, oil and/or soil repellent) to the second side of the textile substrate. The active component of the protective coating is preferably selected from a fluoropolymer, a dendrimer wax or a silicone emulsion.

Brief description of the drawings

By way of illustration, an embodiment of the present invention is described more fully with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of the photoluminescerif material according to a preferred embodiment of the present invention.

Figure 2 is an enlarged cross sectional view of the photoluminescent material of Figure 1.

Figure 3 is a graph illustrating the absorption and emission wavelengths of a phosphorescent pigment used in the photoluminescent material of Figure 1.

Figure 4 is a graph of the light emission from the photoluminescent material of Figure 1.

Detailed description of the preferred embodiment

As illustrated in Figures 1 and 2, the photoluminescent material includes a textile substrate 1, having a base side 3 and a protective side 5. The base side 3 has a coating 7 which contains photoluminescent pigments 9. The protective side 5 preferably has a protective coating 19. The textile substrate 1 is translucent or transparent to permit the photoluminescent pigments 7 to emit and absorb light through the textile substrate 1. TEXTILE SUBSTRATE

The textile substrate 1 is preferably made of polyester although other synthetic fibres such as polyamide may also be used. It is conceivable that non-woven textiles may also be used. Non-woven textiles are those which are neither woven nor knit, for example felt. Non-wovens are typically not strong (unless reinforced by a backing), and do not stretch. Non-woven fabric is manufactured by putting small fibers together in the form of a sheet and then binding them either mechanically (as in the case of felt), with an adhesive, or by interlocking them with serrated needles such that the inter-fiber friction results in a strong fabric.

The textile substrate is translucent or transparent such that the photoluminescent pigments can absorb and emit light through the textile substrate. The substrate material preferably transmits at least 40% of visible light, more preferably 60% of visible light, and even more preferably at least 75% of visible light. However, it will be appreciated that other translucency levels may still achieve an advantageous result.

As illustrated in Figure 2, the textile substrate may consist of fibres 15 with void spaces 13. Therefore the translucency of the textile material will be dependent upon the % area of fibres 15, which may absorb and emit light. Preferably the textile material, such as fibres, will be translucent. The will enable a tight knit, woven or non-woven textile to be produced containing the desired mechanical properties such that the protective side 5 is sufficiently durable to protect the base coating from abrasions, scuffing or other mechanical damage. Advantageously, durable textile substrate is made of translucent fibres to enable light to be both absorbed and emitted from the photoluminescent pigments 9.

The avoidance of opaque fibres ensures that emitted light from the textile is of uniform brightness. In addition, the use of translucent material will enable the brightness of the product to be increased by using multiple layers of translucent textile substrate 1.

It will be appreciated that the exact specification of the textile substrate will be influenced by its intended end-use application. For instance, textile material for use in safety garments for the construction industry may require a high tear resistance textile to survive the rugged environment which the textile would be expected to be exposed. Similarly, the textile's characteristics would differ if it was to be incorporated into a light weight tent.

The fabrics are selected based upon their compatibility with the various coating polymers as well as the use to which it is desired to put the substrate in the fields of clothing and/or furnishing fabrics as end-use applications.

It has been found that two groups of fabrics are suitable for use in the fields of clothing and/or furnishing: These are:

(1) Polyester woven fabrics, undyed or dyed to a light, usually high visibility fluorescent colour, consisting of 150 denier or 70 denier yarns of spun, monofilament or microfibre: these are used for protective or decorative garments; outer garments and overgarments for labourers working on the roads and overgarments for labourers who work out of doors during all or a part of the night, or otherwise in environmental darkness. These overgarments or capes must have the following characteristics:

(a) they must exhibit a transparency such that M_v [%] = M_v X 100 is greater than 40, with optimal performance expectations at 75 M_v [%]E_V

Where M_v [%] = Luminous Emittance in percent passing through the substrate.

M_v= Luminous Emittance in Lux passing through the substrate.

E_v = Illuminance in Lux applied to the substrate.

Assessment of base fabric transparency is undertaken through the equipment detailed in AS-2663.3-1999 "Textiles - Fabrics for Window Furnishings. PART 3: Vertical and Holland Blinds Appendix B: Determination of Opacity of Fabric." Illumination source is a 5OW domestic light assembly with reflector. The Incident light applied for the assessment is 44,000 Lux.

(b) sufficiently strong in the lengthwise or warp direction of the fabric;

(c) have adequate tear resistance;

(d) the coated fabrics or garments need to remain supple under frosty conditions and the shower proofing or waterproofing effect imparted thereto should be adequate to prevent water from penetrating during a fairly heavy shower. The coated film should remain flexible and should not become detached from the textile substrate. Resistance to water vapour transfer is preferably very low, i.e. less than 60 m².Pa/W and preferably less than 40 m².Pa/W, so that the coated garment is comfortable to wear.

(2) Polyamide woven fabrics, undyed or dyed to a light colour, consisting of 70 or 210 denier yarns: these are used for protective or decorative garments; outer garments and overgarments for labourers working on the roads and overgarments for labourers who work out of doors during all or a part of the night, or otherwise in environmental darkness. These overgarments or capes must have the following characteristics:

Where M_v [%] = Luminous Emittance in percent passing through the substrate.

M_v = Luminous Emittance in Lux passing through the substrate.

E_v = Illuminance in Lux applied to the substrate in question.

Assessment of base fabric transparency is undertaken through the equipment detailed in AS-2663.3-1999 "Textiles - Fabrics for Window

Furnishings. PART 3: Vertical and Holland Blinds Appendix B: Determination of Opacity of Fabric." Illumination source is a 5OW domestic light assembly with reflector. The Incident light applied for the assessment is 44,000 Lux.

(b) sufficiently strong in the lengthwise or warp direction of the fabric;

(c) have adequate tear resistance;

(d) the coated fabrics or garments need to remain supple under frosty conditions and the shower proofing or waterproofing effect imparted thereto should be adequate to prevent water from penetrating during a fairly heavy shower. The coated film should remain flexible and should not become detached from the textile substrate. Resistance to water vapour transfer is preferably very low, i.e. less than 60 m².Pa/W and preferably less than 40 m²Pa/W, so that the coated garment is comfortable-to wear.

Given the performance characteristics of the textile substrate, it is not surprising that conventional exterior coatings were prone to deteriorate through mechanical and/or chemical wear.

BASE COATING

The base coating 7 may be formed through a succession of layers. For instance, an initial bonding layer may be directly applied to the textile substrate, to ensure a secure bonding of the base coating to the textile substrate. Successive coating layers with varying viscosities may be added to optimise the concentration and distribution of photoluminescent pigments. The base coating 7 may assume the form of a film, typically having a thickness of between 40 to 200 microns.

The coating may be applied via a variety of coating techniques, including roller or blade- coating based techniques. The coating conditions are preferably adjusted to avoid the penetration of the coatings through the substrate. For example, the coating knife or doctor blade settings may be adjusted to avoid the penetration of the first layer or subsequent layer(s) into the substrate. The base coating 7 preferably contains 40% to 60% (w/w) photoluminescent pigmentary additive, with the photoluminescent pigmentary additive preferably being at least 25% (w/w) (up to 60% ) of the mass of the photoluminescent textile material.

The photoluminescent pigment is preferably dispersed in a synthetic prepolymer resin or prepolymer, with a solvent added to lower the viscosity of the mixture to facilitate handling and application of the coating mixture onto a substrate. A prepolymer is a polymer of relatively low molecular weight, usually an intermediate between a monomer and the final polymer, which may be mixed with compounding additives, and which is capable of being hardened by further polymerisation. A crosslinking additive and a crosslinking catalyst may also be included to promote the crosslinking of the prepolymer. Other additives, such as anti-static agents (eg. Rhodafac RE-610™) may also be added.

Suitable prepolymers may include, but are not limited to, low density polyethylene, high density polyethylene, polypropylene, polystyrene, polyacrylic acid and copolymers of polyacrylic acid and polystyrene, polyurethane (eg. Witcσflex 974™, Reflex 585AXL™ ) , polyvinylchloride, polyvinylflouride, acrylonitrile-butadiene-styrene terpolymers, acrylonitrile-polyacrylate (eg. Viscopol 8880™), styrene-acrylonitrile copolymers, styrene butadiene copolymers, poly(4-methyl-pentene-1), polybutylene, polyvinylidene chloride, polyvinyl butyral, polyvinyl imidazole, chlorinated polyethylene, polyethylene oxide, ethylene-vinyl acetate copolymers, polyvinyl acetate polyvinyl alcohol, polymethylmethacrylate, polymethyl-acrylate, ethyleneracrylic acid copolymers, ethylene-acrylic acid metal salt copolymers, chlorosulphonate polyolefins, polyesters such as polyethylene teraphthalate and polybutylene teraphthalate polyamides such as Nylon 6, Nylon 11, Nylon 13, Nylon 66, polycarbonates and polysulfones, and polyarylene and polyalkylene oxides; agrose glycolic acid(s), polycarprolactone, polycarbonates, polyesteramides, polyanhydrides, poly(amino acids), polyorthoesters, poly(hdroxyalkanoates) polyacetyls, polycyanoacrylates, polyetheresters, poly(esters), poly(dioxanone)s, poly(alkylenealkylate)s, copolymers of polyethylene glycol and polyorthoester, poly(hydroxy acids), poly(lactones), poly(amides), poly(ester-amides), poly(amino acids), poly(an hydrides), poly(ortho-esters), poly(carbonates), poly(phosphazines), po!y(thioesters), polysaccharides and mixtures, blends and copolymers thereof.

Suitable solvent may include, but are not limited to acetone, methyiethylketone, ethylene glycolmonomethylether acetate, acetic acid ethyl ester, dimethyl formamide, N- methylpyrrolidone, cyclohexanone or tetrahydrofuran and combinations thereof.

The cross linking additive may include, but are not limited to isocyanates and polyisocyanates, melamine (eg. Porotan 505™) or sulfur-containing polyamine compounds.

Examples of polyisocyanates include di- or triisocyanates as well as mixtures thereof. Specific examples are aromatic diisocyanates such as 4,4'- methylenediphenylenediisocyanate, 4,6-di-(trifluoromethyl)-1 ,3-benzejτe dϋsocyanate, 2;4-toluehediisocyanate, 2,6-toluene diisocyanate, o, m, and p-xylylene diisocyanate, 4,4'-diisocyanatodiphenylether, 3,3'-dichloro-4,4'-diisocyanatodiphenylmethane, 4,5'- diphenyldiisocyanate, 4,4'-diisocyanatodibenzyl, S.S'-dimethoxy^^¹- diisocyanatodiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenyl, 2,2'-dichloro-5,5'- dimethoxy-4,4'-diisocyanato diphenyl, 1,3-diisocyanatobenzene, 1 ,2-naphthylene diisocyanate, 4-chloro-1 ,2-naphthylene diisocyanate, 1 ,3-naphthylene diisocyanate, and 1,8-dinitro-2,7-naphthylene diisocyanate and aromatic tri-isocyanates such as polymethylenepolyphenylisocyanate.

Suitable isocyanates include alicyclic diisocyanates such as 3-isocyanatomethyl-3,5,5- trimethylcyclohexylisocyanate; 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate; aliphatic diisocyanates such as 1,6-hexamethylenediisocyanate, 2,2,4-trimethyl-1 ,6- hexamethylenediisocyanate, and 1 ,2-ethylenediisocyanate; aliphatic triisocyanates such as 1 ,3,6-hexamethylenetriisocyanate; aromatic tri-isocyanates such as polymethylenepolyphenylisocyanate (PAPI); cyclic diisocyanates such as isophorone diisocyanate (IPDI) and dicyclohexylmethane-4,4'-diisocyanate. Also useful are isocyanates containing internal isocyanate-derived moieties such as biuret-containing tri-isocyanates such as that available from Bayer as DESMODUR N-100™ isocyanurate-containing tri-isocyanates such as that available from HuIs AG, Germany, as IPDI-1890, and azetedinedione-containing diisocyanates such as that available from Bayer as DESMODUR TT™. Also, other di- or tri-isocyanates such as those available from Bayer as DESMODUR L™, and DESMODUR W™, and tri-(4-isocyanatophenyl)- methane (available from Bayer as DESMODUR R™) are suitable.

Commercially available blocked aromatic po Iy isocya nates include Baygard EDW™ available from Bayer Corp. and Hydrophobol XAN ™ available from Ciba-Geigy.

Catalysts, such as Porotan 200™, may also be added to activate the crosslinking process.

The finishing layer 11 consists of a white-pigmented coating, which reduces change in photoluminescent appearance as a result of change in background materials. The finishing layer 11 of the base coating may include titanium dioxide pigments. When exposed to external light, the titanium dioxide pigments 17 reflect light onto the photoluminescent pigments 9 and thereby increase the amount of light absorbed by the photoluminescent pigments 9. In darkness, the titanium dioxide pigments 17 reflect light from the photoluminescent pigments 9 through the translucent textile substrate 1.

PHOTOLUMINESCENT PIGMENTS

The photoluminescent pigments 9 are preferably a long afterglow halo-aluminate photoluminescent material activated by rare-earth elements, such as VGS2 ™ or VGS3 FAP™ produced by Visionglow Global Limited or may alternatively be Luxilum™ grades of similar performance produced by Niteglow Proprietary Limited. The pigments preferably have a specific gravity ranging from 0.25 - 3.6 g/cm³. Further details relating to these pigments are provided in Australia provisional application 2005905974 which is incorporated herein by reference.

The photoluminescent pigments absorb light and then re-emit it over a length of time. This occurs when electrons absorb energy in the presence of light and move up to a higher orbit. In the absence of light energy, these same electrons fall from a higher energy level to a more stable energy level. When this occurs, they emit energy in the form of visible light. This technology absorbs light in the 200 - 450 nm wavelength band, which is invisible to the naked eye, and re-emits the energy in the visible spectrum, peaking preferably at about the 520 nm wavelength region (Figure 3). After exposure of the photoluminescent material to light within the 200 - 450 nm band wavelength range sufficient to become fully charged, the product is expected to glow for about 30 - 60 minutes (phase 1) and still be quite visible in pitch black environments to the dark acclimatised eye (Figure 4). It will be appreciated that the amount of light emitted from the photoluminescent material will depend on factors such as the duration of exposure to light, the wavelength constitution of light source and the amount of light energy (measured in units of lux) received by the fabric during charging. The glow of the material is still apparent from 60 - 90 minutes (phase 2) after the photoluminescent pigments 9 have been charged. An extended afterglow may occur for about a further 5 hours, with a consistent afterglow observed to last as long as two days without the photoluminescent pigments 9 recharged.

The photoluminescent pigments may include phosphorescent phosphor pigments such as crystalline metal oxide aluminates containing one or more of strontium, magnesium, barium and calcium and are activated by europium and at least one co- activator, such as ytterbium, dysprosium or the like. The phosphorescent phosphor include SrAbO₄; Eu, Dy which emits light at about 520 nm. Other phosphorescent phosphors emit blue light (about 442 nm), blue-green light (about 490 nm) and green light (about 500 nm).

PROTECTIVE COATING

The protective side may have a protective coating layer 19 which enhances the material's resistance to the external environment. The coating 19 preferably includes a fluoropolymer and a bonding agent. The bonding agent may also function as a cross linking agent, with the process of cross linking the fluoropolymer also bonding the fluoropolymer to the substrate.

A fluoropolymer is a polymer that containing atoms of fluorine and may include Oleophobol S™, PTFE (polytetrafluoroethylene, Teflon™), PFA (perfluoroalkoxy polymer resin, also known as Teflon™), FEP (fluorinated ethylene-propylene, also known as Teflon), ETFE (Tefzel), (Fluon), ECTFE (Halar™), PVDF (Kynar™), PCTFE (Kel-F™), TFE (trifluoroethanol), FPM, CTFE, FFKM (Kalrez™, Tecnoflon™ FFKM), FKM (Viton™, Tecnoflon™)

The fluoropolymer treatment imparts oil, water and soil repellency to the protective side of the product, and further renders effective the single direction moisture transfer functionality of the moisture vapour permeable resin system on the base side. This enables moisture transport from base side to environment (protective side), yet preventing the transfer of field environment water and moisture from penetrating to the base side of the photoluminescent material.

Alternative repellent formulations based on dendrimer wax or silicone may also be advantageously used.

The photoluminescent textile substrate of the present invention is remarkable in that it comprises a translucent textile to which a coating layer adheres, the coating layer may include one or more synthetic resins admixed with a photoluminescent pigmentary additive and other process or performance aids, dependant upon the end-use application, and requirements of the polymer binder system.

There may additionally be provided between the said flexible substrate and the said coating layer, a bonding layer comprising one or more synthetic resins admixed with a photoluminescent complex.

EXAMPLE 1

A moisture vapour permeable apparel fabric, offering three different means of repellent delivery to the field service side of the textile.

The textile substrate is a high visibility yellow translucent oxford woven 150 denier polyester (76 X 54 threads per inch 15Od x 15Od) Sequenced coating layers are applied to the translucent textile substrate in succession, on the back (non-field-service or base side) of the fabric. Drying takes place between successive coating layers up to 13O⁰C, with the application of a finishing layer and system curing up to 18O⁰C. Directly afterwards, the face side of the textile substrate is treated with a durable, repellent process. Curing is effected at 18O⁰C. The formulations used are as follows:

First layer (base side coating);

100 parts of moisture vapour permeable, clear polyurethane resin w/w, (45 w% non- volatiles ) 16 parts of methylethyl ketone solvent w/w,

2.5 parts of melamine crosslinking additive w/w, ( 50w% non-volatiles ) 1.5 parts of catalyst for crosslinking activation w/w. ( 25w% non-volatiles )

Sufficient dry add-on (non-volatile material) is applied to seal the fabric to prevent penetration from subsequent coatings and to provide a coherent key for overall coating adhesion to the substrate. This coating is applied at high viscosity, as high as can be tolerated by the application process in providing an even coverage of the substrate. The methylethyl ketone content may be varied to optimise the viscosity of the layer. The high viscosity of the coating minimises the potential for the coating (and subsequent coatings) to penetrate into the substrate. The first layer is dried at between 80⁰C to 13O⁰C for sufficient time to remove volatile matter, but without activating crosslinking of the resin.

Second and third layers:

100 parts of moisture vapour permeable, clear polyurethane resin w/w, (45% non- volatiles ) 80 parts of halo-aluminate phosphorescent pigment w/w, (100% non-volatiles SG«2.3) 12 parts of methylethyl ketone solvent w/w, 6 parts of melamine crosslinking additive w/w, ( 50% non-volatiles ) 2 parts of catalyst for crosslinking activation w/w. ( 25% non-volatiles ) Sufficient dry add-on is applied in the coating passes in order to deliver the desired quantity of photoluminescent pigment to the product. The viscosity of the coating is preferably less than the first coating layer to promote an even flow of the coating across the substrate. The second and third layers are preferably thicker than the first layer due to functional requirement to carry the required amount of phosphorescent pigment.

The second and third layers are dried at between 8O⁰C to 13O⁰C for sufficient time on each pass to remove volatile matter, but without activating crosslinking of the resin.

Finishing layer:

100 parts of moisture vapour permeable, clear polyurethane resin w/w, ( 30% non-volatiles )

15 parts of titanium dioxide dispersion w/w, ( 50% non-volatiles )

5 parts of methylethyLketone solvent. - - - -

Sufficient dry add-on is applied to the coating pass in order to provide a white, opacifying finish coat to the product, and to facilitate seam-sealing operations in apparel fabrication. Drying to 13O⁰C and subsequent curing at 16O⁰C is applied to remove volatiles and to activate crosslinking of undercoats, and fuse the coating accumulation to a single film.

Face coating treatment:

100 parts of water w/w, 0.1 parts of acetic acid [33% cone] w/w,

4 parts of fluoropolymer dispersion or colloid w/w, (25% non-volatiles) 1 part crosslinking agent w/w. (25% non-volatiles)

Sufficient dry add-on is applied during the coating pass (or padding pre- treatment) to provide a water, oil and soil repellent finish to the field service side of the fabric. The coating is dried at about 8O⁰C to 16O⁰C. for sufficient time to remove volatile matter. The coating is then cured at 18O⁰C for sufficient time to activate crosslinking and bonding of the polymer to the textile substrate. The first, second and third layers represent different formulation viscosities. The use of different coating application settings may also be employed to resist penetration of the coating through the fabric substrate, and to enable the solids add-on goals to be progressively attained. The add-on goals are the target quantity (and composition) of the specified layers. The successful application of the specified coatings on the substrate will ensure that the properties of the photoluminescent material conform to expectation.

The properties of the resulting photoluminescent material are provided in the following table:

EXAMPLE 2

A back-pack type textile, offering three different means of repellent delivery to the field service side of the textile.

The textile substrate is a plain woven translucent 300 denier polyester (30Od x 30Od). Sequenced coating layers are applied to the translucent textile substrate in succession, on the back (non-field-service or base side) of the fabric. Drying takes place between successive coating layers up to 13O⁰C, with the application of a finishing layer and system curing up to 180⁰C.

First coating layer (base side): 100 parts of acrylonitrile-polyacrylate emulsion resin w/w, (51 % non-volatiles ) 1 part of 25% ammonia aqua w/w, 5.0 parts polyacrylate thickener

Sufficient dry add-on is applied to seal the fabric to prevent penetration from subsequent coatings and to provide a coherent key for overall coating adhesion to the substrate. This coating is applied at high viscosity, as high as can be tolerated by the coating process. The coating is Dried to 13O⁰C for sufficient time to remove volatiles without activating crosslinking.

Second and third coating layer:

100 parts of aliphatic polyurethane granules, 225 parts of methyl ethyl ketone solvent w/w and 225 parts dimethyl formamide solvent w/w for polyurethane solution,

385 parts of halo-aluminate phosphorescent pigment w/w, ( 100% non-volatiles - S.G. ~ 2.3 ) 0.85 parts of antistatic additive, 42 parts of blocked isocyanate crosslinker w/w, ( 75% non-volatiles )

Sufficient dry add-on is applied in the coating passes to deliver the prescribed quantity of photoluminescent pigment to the product. The coatings are progressive. The coatings are Dried from 13O⁰C to 17O⁰C for a sufficient time on each pass to remove volatiles and initiate crosslinking and fuse the coating accumulation into a single film.

This coating pass provides a waterproof finish coat to the product, and delivers abrasion resistance protection to the coating side for industrial (eg. backpack) fabrication.

Each layer may represent different formulation viscosities and the use of different coating conditions, to resist penetration of the coating through the fabric substrate, and to enable the solids add-on and performance goals to be progressively attained.

Face coating treatment

Pre-treatment to the face or protective side of the textile substrate is undertaken with a durable, repellent process. Curing is effected at 18O⁰C in the course of subsequent processing. The formulation used is as follows:

Face coating treatment ( repellent ):

100 parts of water w/w, 0.1 parts of acetic acid (33% cone.) w/w,

Sufficient dry add-on is applied this pre-treatment pass to provide a water, oil and soil repellent finish to the field service side of the fabric. The coating is Dried to 12O⁰C for sufficient time to remove volatiles without activating crosslinking a of the polymer.

The properties of the resulting photoluminescent material are provided in the table below:

The following tables depict the performance of the photoluminescent material of Examples 1 and 2 for selected light sources with various charging times and illumination.

Performance of the photoluminescent material under exposure to direct or diffused sunlight.

Performance of the photoluminescent material under exposure to Incandescent Lamp (2700 K incandescent lamp)

Exposure Time (mins) Expected Performance (mins)

The 150 W Xenon Lamp may also be used assess the performance of the photoluminescent material, as many fluorescent and incandescent light sources have spectra similar to that of Xenon lamp. Xenon lamp is used as a standard source of illumination for defining photoluminescence. Various modifications may be made to the composition, design and process of making the photoluminescent material without departing from the scope and ambit of the invention.

It will be understood that the invention disclosed and defined in this specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

Claims

1. A photoluminescent material comprising:

a textile substrate having a base side and a protective side, the base side having a coating containing photoluminescent pigment,

wherein the textile substrate is translucent or transparent to permit the phosphorescent pigment to emit and absorb light through the textile substrate.

2. The photoluminescent material of claim 1 , wherein the protective side includes a coating layer which enhances the substrates' resistance to the external environment.

3. The photoluminescent material of claim 2, wherein the coating layer of the protective side includes- an -active ingredient selected^" from the group consisting of fluoropolymers, a dendrimer waxes; and silicones.

4. The photoluminescent material of claim 1, wherein the base side further comprises an additional protective layer, the additional protective layer is located on the external surface of the base coating.

5. The photoluminescent material of claim 1, wherein the textile substrate transmits at least 40% of visible light.

6. The photσluminescent material of claim 5, wherein the textile substrate transmits at least 60% of visible light.

7. The photoluminescent material of claim 6 wherein the textile substrate transmits at least 75% of visible light.

8. The photoluminescent material of claim 1 , wherein the base coating comprises at least one layer having the photoluminescent pigments disperse in a synthetic prepolymer resin or prepolymer.

9. The photoluminescent material of claim 8, wherein the synthetic prepolymer resin is selected from the group consisting of polyurethane resins, polyvinyl chloride base resins, polyacrylate resins and elastomeric silicone resins.

10. The photoluminescent material of claim 1, wherein the base coating contains up to 60% (w/w) photoluminescent pigment on a non-volatile basis.

11. The photoluminescent material of claim 10, wherein the base coating contains between 40% and 60% (w/w) photoluminescent pigment.

12. The photoluminescent material of claim 10 or 11 wherein, the photoluminescent pigment comprises at least 25% (w/w) of the mass of the photoluminescent material.

13 The photoluminescent material of claim 1, wherein the first base_coat layer is a bonding layer, the bonding layer adhering directly to the surface of the textile substrate.

14. The photoluminescent material of claim 1, wherein the final base coat layer contains titanium dioxide pigments.

15. The photoluminescent material of claim 1, wherein the textile substrate has a water vapour transfer less than 60 m².Pa/W.

16. The photoluminescent material of claim 1 , wherein the photoluminescent pigment is a halo-aluminate photoluminescent material activated by a rare earth element.

17. A photoluminescent material comprising:

a textile substrate having a base side and a protective side, the base side having a coating containing a photoluminescent pigment, the textile substrate is translucent or transparent to permit the phosphorescent pigment to emit and absorb light through the textile substrate, wherein the base coating includes a first layer and a second layer, the first layer forming a secure bond to the substrate and the second layer containing photoluminescent pigment.

18. A photoluminescent material of claim 17, wherein the viscosity of the first layer, as it is applied to the substrate, is sufficiently high to prevent penetration of the layer and subsequent layer(s) into the textile substrate.

19. A photoluminescent material of claim 17 or 18, wherein the viscosity of the second layer is sufficiently low to ensure even distribution of photoluminescent pigment across the substrate.

20. A photoluminescent material of claim 17, wherein the first layer has a viscosity higher than the second layer.

21. The photoluminescent material of claim 17, wherein the non-volatile component of the first layer is applied at a rate of 15 to 25 grams per square metre.

22. A photoluminescent material of claim 17, wherein the base coating further includes at least one more layer containing photoluminescent pigment.

23. The photoluminescent material of claim 17, wherein the non-volatile component of the second and subsequent photoluminescent pigment containing layer(s) is applied at a rate of 50 to 120 grams per square metre.

24. The photoluminescent material of claim 17, wherein each of the layers forming the base coating includes a prepolymer, with the base coating being cured to crosslink the prepolymer to form an integral base coating.

25. The The photoluminescent material of claim 17, wherein the first layer contains a prepolymer, the first layer being cured to crosslink the prepolymer, thereby securely bonding the first layer to the substrate.

26. A method for producing a photoluminescent material comprising the steps of:

27. The method of claim 26, wherein the viscosity of the first layer is adjusted to prevent penetration of the first layer and subsequent layer(s) into the substrate.

28. The method of claim 26, wherein the first layer comprises a prepolymer, a solvent and a crossliήkihg additive.

29. The method of claim 28, wherein the solvent level of the first layer is adjusted to change the viscosity of the first layer such that the base coating does not penetrate the textile substrate.

30. The method of claim 26, further comprising the step of drying each base coating layer to remove the solvent prior to the application of the next layer.

31. The method of claim 30, wherein the each base coating layer is dried between 8O⁰C to 13O⁰C.

32. The method of claim 26 or 30, further comprising the step of curing the base coating.

33. The method of claim 32, wherein the based coating is cured (crosslinking the prepolymers) at between 16O⁰C and 18O⁰C.

34. The method of claim 33, wherein the curing step creates a secure bond between the first layer and the textile substrate.

35. The method of claim 26, further comprising a textile substrate pre-treatment step to enhance the strength of the bond between the textile substrate and the first layer.

36. The method of claim 35, wherein the pre-treatment step includes treating the surface of the substrate with a chemical or other treatment (eg. corona discharge) to enhance the ability of the substrate to bond with the first layer.

37. The method of claim 26, wherein the second layer includes a prepolymer, a solvent and a crosslinking additive.

38. The method of claim 26, wherein the solvent level of the second layer is adjusted to promote an even distribution of photoluminescent pigment across the substrate.

39. The method of claim 26, further comprising the step of appjying one or more layers, containing photbluminescent pigment, to the second layer.

40. The method of claim 26, further comprising the step of applying a finishing layer, the finishing layer containing titanium dioxide.

41. The method of claim 33, wherein the curing step is accelerated by use of elevated temperatures, UV light and/or the addition of a crosslinking catalyst.

42. The method of claim 26, further comprising the step of applying a protective coating to the protective side of the textile substrate.

43. The method of claim 42, wherein the active component of the protective coating is selected from a group consisting of fluoropolymers, a dendrimer wax; or silicones.

44. The method of claim 26, wherein at least one of the layers is applied by use of a coating knife or doctor blade.

45. The method of claim 44, wherein the coating knife or doctor blade settings are adjusted to avoid the penetration of the first layer or subsequent layer(s) into the substrate.