WO2007056820A1

WO2007056820A1 - Luminescent paint composition

Info

Publication number: WO2007056820A1
Application number: PCT/AU2006/001733
Authority: WO
Inventors: Steven James Hays; Mark Andrew Stevens; Ramakant Choudari
Original assignee: Nightsafe Enterprises Pty Ltd; Asian Paints (Queensland) Pty Ltd
Priority date: 2005-11-21
Filing date: 2006-11-17
Publication date: 2007-05-24
Also published as: AU2006202681A1

Abstract

A paint composition having luminescent qualities when applied and dried, said composition including: a latex resin material, at least one solvent material including at least one coalescing solvent, at least one pigment containing particles of luminescent material, wherein the composition maintains a viscosity suitable for both spray application and maintaining the particles in suspension while drying after application.

Description

LUMINESCENT PAINT COMPOSITION

FIELD OF THE INVENTION

The present invention relates to paint compositions and particularly to a photo luminescent water based paint composition suitable for either marking roads or other areas, predominately with one application. However the composition may have many other applications other than as a road or pavement paint.

BACKGROUND ART

Luminous products and pigments have been known for many years and often referred to by other names such as photo luminescent, phosphorescent or luminescent. These pigments have been known to be integrated into plastics etc in the form of extrusions etc. Previously most luminous pigments were from the family of zinc sulfides and have limited uses due to an extremely short glow time and therefore unsuitable for effective emergency egress products. Until recent years luminous products were mainly seen as novelty items eg. The stars on children's ceilings and toys.

One form of the present invention is directed to a paint composition containing luminous pigments, not limited to dry powder.

US patent no. 6359048 relates to a oil based tintable formula of luminous paint which can be tinted with a small addition of standard tints. It is considered that most, if not all, coloured tints (in quantities to make an aesthetically pleasing colour) will block light from reaching the luminous particles. The exception to this is fluorescent tints which are very susceptible to breakdown from UV rays and only achieve a life span of 2-3 months outdoors. The pigment loading rates mentioned in this patent also make the product very expensive with loading rates up to 50%. It is also considered that adding such an amount of pigment changes the chemical make up of the formula and therefore affect shore hardness and its ability to take heavy traffic for any extended period. Reflective paints and the like used to mark roadways and other areas are known in the art. Common paints are made reflective with the addition of glass beads.

It is known that reflective paints, when excited by a source of light, produce an emission of light but the light emission is limited to the period of excitation. Once the source of the light is removed, no light emission is possible. Such paints can be selected to provide a day time coloration which will demarcate and emphasize the highway edges and median traffic divider stripes.

Photo luminescent paints on the other hand, once they have been excited, remain luminous with a soft, slowly decaying emission or radiation in the form of a glow. Such photo luminescent paints can generate a useful level of luminous flux for periods of time (often several hours) when exposed to sunlight or artificial light (such as from headlights of automobiles) in the dark of night. After the glow has decayed to its maximum, luminescence can be restored by once again exposing the paints to either a natural or an artificial light. Thus, highway paints have incorporated reflective paint to demarcate the edges of highways and the median line of the highway to differentiate the different directions of the highway vehicles. Previously highway paints, due to chemical attack by the atmosphere on the phosphor, often lose their reflective capacity in six to twelve months.

A marking paint composition should be easy to apply, have a short track time, long wearability and suitable luminescence. In most cases, the road marking paint is applied by spraying apparatus and therefore the paint needs to be suitable for this purpose. The present invention is suitable for spray, brush and roller applications, therefore making it suitable for marking roads, step edges, corridors, pathways etc and any other application where this type of composition may be useful.

It is not considered that the invention should be limited to the specific uses of the composition described.

There are several procedures which have been used in the past for marking highways, their object being that the applied coating composition dries rapidly and preferably within a time period of 1 to 4- 8 minutes or less.

One such technique that has gained wide acceptance is described in U.S. Pat. No. 3,474,057. In that patent extremely fast dry times of road marking materials is achieved with the use of heat (commonly referred to as hot melt thermoplastic); that is, the paint composition is heated in a closed system to a temperature of 60° to 120° Celsius then released from the system and sprayed onto the road surface in order to mark the road surface and permit the paint to dry quite rapidly, generally in less than about 3 minutes or less.

While heating road marking paints and compositions, such as those mentioned above, has met with substantial commercial application, it is necessary to use rather elaborate equipment, which must be portable, and requires not only maintenance during operation but also the use of a separate heat source for raising the heat of the road marking composition carried by the equipment.

Other road marking compositions and procedures are described in U.S. Pat. Nos. 3,046,851, 3,136,733 and 3,321,329. While the paint compositions described in these patents are applied without the use of heat, the dry time required to obtain a suitable marking line which can be traversed by vehicles and road traffic is at least greater than 20 minutes, and generally of the order of about 40 minutes or more. Such compositions usually require the use of road marking cones and the like to direct traffic away from the wet composition until a suitable non-tracking film has formed on the marked road surface. This practice can be very costly if delaying or diverting traffic repetitively. If 2 coats are required as with some of the above mentioned patents, recoat time can be up to 6 hours.

Other prior procedures have used drop-on glass spheres, sand, particulate matter or the like in order to reduce the drying time of the applied paint composition. An example of this is a rounded sand such as crystal grade silica sand in a mixture ratio of one part glass spheres to two parts round sand. Using spheres or mineral matter in such a procedure, when applied to a wet film on the highway surface the close packing of the spheres which are subsequently applied provides a surface which is free from wet paint composition on the upper surface, yet it is rather immobile due to the solvent loss occurred in spraying. The glass-mineral surface is sufficient to support the tires of an automobile passing over the marked surface without touching the wet paint composition below the glass-mineral coating.

A well known base for road marking paint is manufactured by Rohm and Haas and is

„ known as FASTRACK (trade mark). Details of this emulsion can be found on the

Rohm and Haas website. There are various types of FASTRACK compositions but all are acrylic compositions which upon drying form a tough coating. Various tests have been done to vary temperature, humidity and the type of binder in order to determine the durability of the coating. It is known to add pigments to this product to provide a road paint with reflective qualities.

There is an advantage in providing a road paint with photo luminescent properties (that is glow in the dark type properties), as opposed to simple reflective properties

(which can be obtained by glass beads). Pigments that provide photo luminescent properties are known. For instance, a known type of pigment is VISIONGLOW VGS-

3 ( trade mark) pigment. Pigments from the AURA ( trade mark) family, Nomoto &

Honeywell are also known. Details of the first 2 pigments are described in Table 1 and Table 2 below.

m previous attempts to ^"produce a marking paint having all of these qualities, one or more of the qualities have been sacrificed in preference to other qualities. For example, it has been found that when adding luminous pigments to a paint ^' composition, the specific gravity of the preferred luminous pigment should be reasonably close to the specific gravity of the paint formulation. If this is not the case, when applied the luminous pigment is heavier than the paint composition and can sink before the paint has dried.

Further, when a luminous pigment with unstable pH due to impure additives is combined with the paint composition, the mixture solidifies rather rapidly in some cases. . Thus, merely adding a luminescent pigment to a paint ( for instance a road marking paint) does not provide a good product as it is found that the pigment does not remain uniformly dispersed in the paint composition. Other common problems are light blocking characteristics of many standard formulas, pH fluctuations and instability of unpurified luminous pigments due to additives and extenders commonly create. premature hardening of the paint and very limited shelf and storage life. This can sometimes occur in a matter of minutes or days.

After much research and experimentation, it has now been realised that a luminescent pigment can be added to a paint ( for instance a road marking paint) to provide a composition having acceptable properties (e.g. the formula does not harden etc) by ensuring the pH of the luminous pigment is closely matched to the paint composition and/or that the preferred luminous pigment is suitably purified. The purification process may be carried out using a Thermo process with a Catalytic agent to remove unwanted minerals by evaporation or condensation.

A paint composition should be easy to apply, have a short track time, long wearability and suitable luminescence after application and certainly after drying.

The present invention is particularly directed to the realization that the carrier of the luminescent particles does not need to be a clear or transparent medium, usually providing that a particular paint formulation is used

The present invention may also allow production of a one part formula in several colours, alleviating the need to use a common three part system such as, a white primer , the luminous pigment in a clear carrier and then a clear protective top coat.

The use of a white primer aids in the ability of the pigmented carrier to glow. As the pigmented carrier is a clear base, no luminosity would be noticed if placed on a dark substrate. The paint formulation of the current invention can be applied to a black or very dark substrate with no ill effects.

The formulations of the present invention have. many applications whereby the painted surface can act as a way finding device in the event of power failure or when a point of reference is necessary to avoid hazards in darkness. It has been known that some applications can provide a very effective visual marker to allow safe public egress in stair wells and corridors the event of an emergency.

OBJECT OF THE INVENTION

The present invention is directed to a paint composition, which may at least partially overcome the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

The unique formula of the composition according to an embodiment of the invention may allow for less loading rates of the luminous pigment which means more cost effectiveness unlike other formulas which can be loaded as much as 40%.

hi one form, the invention resides in a paint composition having- luminescent qualities when applied and dried, said composition including i. a latex resin material, ii. at least one solvent material including at least one coalescing solvent, iii. at least one pigment containing particles of luminescent material, Wherein the composition maintains a viscosity suitable for both spray application and maintaining the particles in suspension while drying after application.

In an alternative form, the invention resides in a method for formulating a paint composition having luminescent qualities when applied and dried, said composition including i. a latex resin material, ii. at least one solvent material including at least one coalescing solvent, iii. at least one pigment containing particles of luminescent material, the method including the steps of forming a latex paint base by adding a solvent to the latex resin material and mixing, subsequently adding an amount of water, followed by addition of the at least one pigment and mixing.

In another form, the invention resides in a road marking paint composition the composition comprising an aqueous acrylic resin, and a pigment containing particles of luminescent material, the composition having a pH of greater than 7 and typically between 9-12.

While not wishing to be bound by theory, it is believed that there is a relationship between the pH of the latex paint precursor and its viscosity once luminous pigment is added. Ionic systems exhibit the strongest relationship between pH and apparent viscosity. Preferably, the latex paint precursor is pH adjusted until a pH of at least 7.0 is reached and preferably between 9.5 and 12 is reached prior to addition of the at least one pigment. It is found that by providing a common value, the photo luminescent pigment remains more stable in the composition and provides a superior road marking product.

The final paint composition preferably contains 45-50% volatiles by weight in the final product. For a waterborne acrylic traffic paint, the paint composition contains a polymeric binder (an acrylic emulsion), not a solution polymer. This means that there are literally millions of binder particles (emulsion polymers) suspended in water (the "solvent") along with pigments and additives in a container of waterborne acrylic traffic paint. The solvent is preferably a mixture of water and the coalescing solvent, an agent that promotes film formation.

Conventional latex paint is a suspension of finely divided synthetic resins in water. The latex resin material of the invention preferably includes such resins as acrylics, vinyls, and epoxies; among others but a particularly preferred resin material is an acrylic resin.

The latex water-based coating of the present invention preferably cures through conventional processes, namely through latex coalescence, which occurs when both water and any solvents present evaporate, with the resulting pressured causing the latex particles of the coating to bind.

It is preferred that as the latex coating cures, the pigment particle which have been added to the paint prior to application,, remain suspended in the coating layer so remain accessible to incident light. This is obtained by similar specific gravities of the luminous pigment and the paint composition.

The latex paint material formed as a precursor to the final product formulation of the invention will typically contain at least two basic components, namely:

• a resin material, which forms a film or coating on the surface;

• a solvent, which keeps the resin liquefied until the paint is applied to the surface.

The latex paint precursor is typically an emulsion coating. Typical solvents used include water and methylated spirit. According to a preferred embodiment, the acrylic emulsion used to form the latex paint precursor is manufactured by Rohm and Haas, product name Fastrack 3427 ( Trade Mark).

Conventional water-based latex paints typically contain both organic and inorganic ingredients, namely pigments, binder, additives, and water. The volatile organic compounds (VOCs) in these paints are mostly additives consisting of solvents and coalescing solvents that facilitate film formation when the paint is applied.

Many paints are formulated using ethylene glycol, a listed toxicant, as one of the solvents/coalescing solvents, although alternatives may be used in some paints. Typical alternative coalescing solvents include alcohols, esters and glycol ethers. Alcohols are used as coupling agents in waterborne coatings. They typically help provide the proper balance of desired properties such as cure rate, flow and levelling, and viscosity in a formulation. Esters, with limited water solubility, are used as coalescing aids for latex paints.

For example, 2,2,4-trimethyl-l,3-pentanediol mono-isobutyrate is the market leader in trade sale paints as a coalescing solvent despite its odour and slow evaporation rate. Glycol ethers contain both ether and alcohol group in a single molecule. Therefore, they are miscible with most liquids and are mild-odour solvents for many resins. A user can tailor glycol ether molecules to the specific composition by adjusting alcohol group chain length. The longer the alkyl chain length, the more closely the molecular structure of a glycol ether resembles a hydrocarbon, and the more its performance parallels a hydrocarbon. The ether group introduces hydrogen bonding with its attendant influence on solubility performance.

Glycol ethers offer a desirable combination of solubilizing, coupling, and levelling properties, so they are widely used in industrial waterborne coatings as coalescing solvents to promote film formation and improve wetting characteristics of the paints or coatings.

A coalescing solvent or "coalescent" is often used in water-based systems as a fugitive plasticizer to soften the resin particles, enabling them to fuse into a continuous film. During the drying process, most or all of the coalescent evaporates, allowing the film to achieve the desired hardness.

Physical properties of the coalescing solvent determine its efficacy in a particular formulation. Among the most important coalescent properties are its distribution coefficient in the latex, its plasticizing efficacy for the latex, and its rate of evaporation.

Most waterborne coating and paint compositions have some organic solvent in their formulation, since most resins are not truly soluble in water.

The third factor that influences the efficacy of a coalescing solvent is its rate of evaporation. Too fast an evaporation rate can result in premature loss of coalescing solvent and poor film formation. Too slow an evaporation rate can leave coalescing solvent in the film imparting tack to the final film and causing blocking. So there is a trade-off of effective coalescence versus blocking resistance.

In addition, atmospheric humidity will have great impact on water evaporation. Therefore, formulators need to consider atmospheric humidity, and water and coalescent interactions in their formulations. The solvent blend used in the paint composition of the present invention is preferably adjusted to have an optimum distribution between the paint and aqueous phases, coalescing efficacy, and plasticizing ability, including low-temperature coalescence to promote film formation, optimum coating rheology, film property, and blocking resistance.

The viscosity of the latex paint precursor may be a particularly important variable in the paint composition of the invention as it will generally affect the suspension of the pigment particles once they are added to the composition.

A mixture of water and solvent preferably provides a more controlled viscosity reduction while maintaining good film coalescence. Formulation viscosity may also be affected by adding tertiary amines such as triethylamine or dimethylethanol amine, particularly to latex paint precursors which are acidic. Ammonia may also be used to adjust pH or viscosity.

Common benefits for the use of an optimised solvent blend with the resin system are:

• controlled evaporation

• improved pigment wetting • improved rheology

• enhanced substrate wetting

• modified solids/viscosity profile

• lengthened shelf stability

The coalescing solvents will typically increase the viscosity of the formulations in varying degrees; the amount of the increase will depend on the particular solvent's water and resin solubility. For example, in general, higher molecular weight glycol ethers contribute more to viscosity. Since the higher molecular weight analogues are more efficient, they require lower levels of viscosity to perform their function. These solvents are generally used at 1-8% of the total paint volume.

The at least one pigment, which provide the luminous quality to the final formulation is typically added to the latex paint precursor. The pigment will typically include particles which are luminous. The particles are suitably silica aluminate, strontium aluminate or materials containing zinc. The pigment will typically be added to the latex paint precursor in a powder form, liquid concentrate dispersion or sub micron/nano particle liquid dispersions. Preferably, the particles in the pigment will have a particle size that is chosen to prevent "sinking" of the particles in the paint once applied and thereby provide luminescence using light penetrating the applied paint layer. Often photo luminescent paints are a composition of luminous pigments and a clear carrier as in this method light is guaranteed to penetrate the coating and excite the luminous particles. A particularly preferred feature of the current invention is the coating can be a white or yellow in day time appearance, therefore making it suitable for conventional purposes. The unique make up of the formula makes it possible for light to penetrate the paint without any detrimental effects.

A particularly preferred pigment is manufactured by Goldwell Technology Pte Ltd with the family name of Aura pigments. This photo luminescent material can charge in either artificial or natural light and glow for up to 12 hours. Glow colours available are, green, aqua, blue, & violet. Other pigments are very dense, so have been difficult to integrate into plastics, paints, or fabrics. The Aura material has a low specific gravity to match the specific gravity of the host medium. • ^'

The pigment can be integrated into a variety of bases such as compound plastics (both extruded and injection moulded), glass, ceramic glaze coats, resins, silicone bases, solvent based paint systems and water-based paint systems including aerosols.

Commonly most pigment manufacturers will stress that pigment crystals or particles in their processed form can be added into many materials provided the medium is opaque or clear in its final appearance. The paint composition of the current invention does not need to adhere to these stipulations. Table 1.- Technical Specification for Visionglow VGS-2 pigment.

TABLE l Properties

VGS-FAP Series are novel photoluminescent crystals designed for wider range of applicability and slower rate of afterglow decay. They are very stable crystals of oxides and halides of alkaline-earth and aluminum, doped with rare-earth elements. In daylight, the compound has white to pale green colour in appearance and is odorless. The daylight colour depends on the particle size of the powder with smaller particle sizes appearing whiter. This compound is also referred to as pigment as it imparts the characteristic glow-colour in the dark to the host material. A number of chemical and physical properties are listed in Table 1.

This compound is non-toxic, non-radioactive and safe to handle. The afterglow in these crystals is not due to harmful radioactive decay process.

Phosphorescence

VGS - FAP green has green afterglow. The substance requires a brief exposure of 5 minutes to sunlight; or of 20 minutes to artificial fluorescent lights, for it to glow in the dark for 8 hours and longer.

The pigment has the following after-glow characteristic, when irradiated at an illumination of 1000 lux, with light from a 15 watt fluorescent lamp for 5 minutes and the results are described in accordance with DIN 67 510,

VGS-FAP pigments will provide the following minimum brightness (in millicandela per square meter) or more for the above excitation:

Time (mins) 10 30 60 90

Brightness 250 80 40 25

The threshold for human eye in dark conditions is 0.01 millicandelas per square meter, Therefore, the applications of these materials are best seen in very dark conditions.

However, the brightness and duration of the after-glow depends on the type of light used to 'charge' the pigment and the duration of exposure to the light. Brighter lights and longer durations will result in brighter and longer afterglow.

Table 1. Physical and Chemical properties of VGS - FAP pigment

Melting point, ⁰C >900 C

Solubility in water (25X), wt % _, not significant pH in distilled water (measured after 2 days) 7.9

Solubility in 90% βthanoϊ (25"CJ₁ wt % ^' insoluble

Specific gravity 1.8 - 2.2

Moh Hardness 6 - 7 iVWsture content < 0.5 %

Particle Size Distribution Various grades available between 1 micron to 125 microns.

The substance is stable under uv-radiation. humidity and heat. These factors have no effect on either the durability or the glow performance, Reactivity and Stability

The product does not react with most materials (such as resins, paints, etc) that can be used as a host.

It is stable in water based/borne formulations. The compound does not hydrolyze like other available aluminate based phosphors.

The compound does not react with most acids and alkalis.

As the compound is a stable inorganic crystal, the afterglow property remains unchanged for many years.

Paints

The pigment can.be added in most paint formulations at the grind stage. Resins and emulsions in the pH range of 6 - 9.5 can be used for the purpose. Many standard wetting agents, uv-stabilizers, polyphobes and rheology agents can be used along with the pigment.

A typical paint composition would have 20% - 25% of pigment by weight of wet paint, or 15% - 30 % of PVC. The pigment loading, the thickness of coating and the clarity of other solids in the formulation will determine the effective afterglow or brightness of the painted surface.

The suggested vehicle for the pigment is a clear coat. If there is a need for colouring , fluorescent colours should be added in the formulation @ 1% - 2% of the weight of the paint. Any other dye (for colouring) in formulation will NOT be effective and no afterglow will be observed.

Hot Box tests for some paint formulations have been carried out and no loss of glow properties were observed. Please contact Visiongiow if you need starting point formulations.

The typical properties of the preferred AURA ( trade mark) pigment are given in Table 2.

TABLE 2 ^« Application:

Suitable for use as colorant in manufacturing of surface coating material, such as PU paint, emulsion paint, printing ink, silkscreen ink, ceramic glaze. The photoluminescent pigment couid also be used as additive for making of plastic molding materials such as master batch and after-glow plastic sheet, etc.

" Chemical property:

(a) Composition: alkaline earth aluminates jb) Formula: SrAI₂O₄; Eu,Dy

(c) Insoluble in water, alkalis, organic solvents;

(d) Decomposition by acids.

^■ Physical properties

(a) Appearance: yellowish color powder; jb) Specific gravity: 3.6g/cm³;

(c) Temperature resistance: 600⁰C.

" Luminapce properties

(d) Excitation wave length: 240~440nm;

(e) Peak value: 520um;

(f) Glowing color: yellowish-green; pink; blue, beige, orange-red, green, purple, etc. jg) Duration of visibility: > i 2 hours;

(h j Compliances: DIN675 i 0 Part; ASTM 2072E and others.

Luminance Value Graph

PO3S0-9C PIGMENT PG330.9D PIGMENT

a s s

It is preferred that the particle size of the luminous particles in the pigment be within the range of 5 to 65 μm, with an average of approximately 22 μm. TABLE 3 LumiKote ( Trade Mark) Luminescent Pigment

DATA SHEET Issued September 2006

LumiKote ( Trade Mark) Luminescent Pigment is photoluminescent Strontium Aluminate pigment or long afterglow pigment.

LKHV7CK luminescent pigment has particle size of 20um to 40um and is treated to be suitable for inclusion in water based medium. LumiKote luminescent pigment is non-toxic, non-radioactive, non-corrosive powder with specific gravity of 3.4 to 3.6.

LumiKote luminescent pigment is not effected by higher alkilinity, however will be decomposed by strong acids. LumiKote luminescent pigment may cause irritation to the eyes and skin. It is advisable to wear protective glasses and gloves when handling. LumiKote Luminescent Pigment are suitable for use both indoors and outdoors. The expected reduction in light emission after 5 years of outdoor applications is less than 5%. The expected life for indoor applications is greater than 20 years. Luminance Testing;

LumiKote luminescent pigment has been tested after irradiation by a D65 light source (lOOOlux) for 10 minutes. The luminance reading after removal from the light source are as follows.

LumiKote Luminescent Pigments are available in both waterproof and untreated states in particle sizes ranging from 5-8um to 65-100um. Glow colors include yellow/green and blue/green. The paint composition may also include a biocide, which are used to prevent bacterial growth in the storage container. Ammonia and acetaldehyde are frequently used for this function, but formaldehyde is used in some paints.

Typically, the hazardous ingredients of the paint composition of the present invention may be as follows:

Alcohols are used primarily for viscosity reduction and to maintain or improve the speed of drying, but they may also improve stability. These solvents are generally used at 1-5% of the total coating volume.

There is suitably also a relationship between the pH of the latex paint precursor and its viscosity. Ionic systems exhibit the strongest relationship between pH and apparent viscosity. Preferably, the latex paint precursor is pH adjusted until the pH value of the chosen pigment is reached prior to addition of the at least one pigment.

According to a particularly preferred embodiment, the paint composition of the present invention is manufactured by first creating the latex paint precursor using the Rohm and Haas Fastrack 3427 product and a suitable solvent, generally water and a coalescing solvent. An equivalent to the Fastrack may also be used .

Once a conventional latex paint mixture is created^ a further amount of water, normally approximately 3% by weight, may be added to the precursor. This suitably forms a mixture having a pH of approximately 7.5 to 9, and up to 10-12, depending on pigment chosen in the composition Following this, an amount of pigment, preferably approximately 10% up to 20% by weight of the chosen pigment with a particle size of between 5 and 65μm, is added to the mixture and thoroughly stirred, forming the paint composition of the invention and ready for application.

BEST MODE

According to a first particularly preferred aspect, the present invention provides a paint composition having luminescent properties.

The paint composition of the preferred embodiment includes a latex resin material, at least one solvent material including a coalescing solvent, and pigment containing particles of luminescent material, wherein the composition maintains a viscosity suitable for both spray application and maintaining the particles in suspension while drying after application.

The latex paint precursor is an emulsion coating, made by combining solvents including water and a methylated spirit. The coalescing solvent used is 2,2,4- trimethyl-l,3-pentanediol mono-isobutyrate. According to the preferred embodiment, the acrylic emulsion used to form the latex paint precursor is manufactured by Rohm and Haas, product name Fastrack 3427. An equivalent to the Fastrack 3427 may also be used in the future, however to date no such product is available.

A mixture of water and solvent preferably provides a more controlled viscosity reduction while maintaining good film coalescence. The hazardous ingredients of the paint composition of the present invention may be as follows:

The pigment is added to the latex paint precursor in a powder form, liquid concentrate dispersion or sub micron/nano particle liquid dispersions. The particles in the pigment has a particle size chosen to prevent "sinking"' of. the particles in the paint once applied and thereby provide luminescence using light penetrating the applied paint layer.

Example 1.

Processing equipment stainless steel pot of suitable size. Cowles impeller High speed variable speed device depending on size of the pot. Suitable cover to ensure minimal air contact.

Stage 1. Take 50% of the emulsion in a clean Stainless Steel vessel.

Processing: Under slow speed mixing, add Propylene Glycol, wetting agent and surfactant.

Mix for 5 minutes at slow speed.

Add Rutile Titanium and mix at medium speed for 10 minutes.

Add Calcium Carbonate and mix at medium speed for 10 minutes .

Scrape the sides of the Stainless Steel vessel and ensure homogeneity.

Add Thickener and continue to mix for another 10 minutes.

Add Defoamer and Ammonia and mix for 10 minutes at slow spped Ensure the temperature during grind does not exceed 40 degrees

Add water and remaining 50% emulsion and mix at slow speed.

Add Methylated spirit and mix for 5 minutes

Add Texanol and balance quantity of water

Cover pot with 4 Litres of water and cover to avoid skinning. Stage 2. Check the sample for all preliminary properties.

Process Quality Control.

Stage 3 Pack the material in plastic cans only.

Packaging Metal cans require adequate Epoxy phenolic lining.

EXAMPLE 2 Start Point Formulation for Line Marking Pamt

Primal Fastrack 3427 (trade mark) 7.2 L

Dispex A40 113. 8 gms

Teric GN9 61.2 gms

Omyacarb 2 12.0 Kg

Tiona RCL-575 1.2 Kg

Aq. Ammonia 50 mL

Dispelair 3.6 gms

(to adjust the volume of the mill base - then disperse @3000 rpm)

Primal Fastrack 3427 3.0 L Aura PG 300 8B 3.5 Kg Grind stage complete LetDown Ethanol 618 Dispelair 3.6 g Natrosol (5%) 0.1 g Propylene Glycol 200 g Texanol 1321 mL Water * 120 mL

Natrosol 250HR can be added to water in the formulation if necessary.

Yield approximately 20 liters.

The viscosity of this formulation is likely to be between 5 and 6 poise.

This is a start point formulation only and is to be used as a guide for making the product suitable to the application.

Example 3

Example 4

Example 5

Example 6

100.00

WPl - 1.66 to 1.70

Visco - 225 to 260 gms on stormer

Fineness - about 80 microns Touch Dry - Around 2 minutes at 100 microns WFT

Formula of RM if we add about 10 % by wt of Glow Pigment in our formulation.

Example 7

Sp Gravity

1.6 PH

8.5

This slow dry Roadmark paint is produced in SS Tank.

The dispersion is achieved by Cowles High Speed dispersion.

Variable speed device is necessary.

Open tank can be used but preferred to have closed arrangement.

Tank with cooling water circulation arrangement is preferred while producing the paint in hot climate. Emulsion/Binder addition should be at temperature as low as possible.

The fineness of grind should be minimum 60 microns.

THIS COMPOSITION WAS FOUND TO BE UNSTABLE

MEANS IT GELS (THICKENS) AND UNSUITABLE FOR ANY APPLICATION.

Even though the PH is about 8.5, the composition gels soon after it is made The reason is attributed to the Emulsion used in this which is conventinal Styrene acrylic of BASF. The monomer composition present in this emulsion seems to be reacting with Glow pigment as without glow pigment the product is satisfactory in terms of storage and application.

Even though the PH is about 8.5, the composition gels soon after it is made. The reason is attributed to the Emulsion used in this which is conventional Styrene acrylic of BASF. The monomer composition present in this emulsion seems to be reacting 5 with Glow pigment as without glow pigment the product is satisfactory in terms of storage and application.

Example of Use. - Coating Concrete Stair Nosings

10 First the concrete surface was water blasted to remove any grime and provide a clean work surface. Any pinholes or imperfections were first filled with a suitable fairing mortar. Once fairing mortar was dry a heavy coat of the paint formula according to the invention was applied by brush to achieve a dry film thickness (DFT) of 350 microns. The coating was only applied to the edge of the stairs being 50mm of the tread and

15 50mm of the "riser" to only highlight the extremity of the stairs.

In this particular case (due to the heavy industrial nature of the site) fine glass beads were added to the coating while still wet to aid in slip resistance. The stairwell was back in service after 20 minutes and open to foot traffic again. 20 ^{■ '}

As the stairs were in full sunlight during the day, they emitted a very impressive luminous glow after the sun went down. This glow was more than enough to highlight where the stair edges were and allow the employees to carry out their duties with limited risk of injury. This glow was still very visible when employees started work the next morning however not as brightly as when they were first exposed to darkness.

The ease of application means maintenance personnel can quite easily carry out recoating whenever is necessary without calling in specialist contractors or using specialty products.

Advantages obtained by the invention include the following:

- The uniqueness of the formula means lower loading rates of photo luminescent pigments. Most of the other formulas call for the addition of photo luminescent pigments @ 20-40% current invention is 10-20% by weight therefore being much more affordable to the end user.

White or yellow daytime colour allows for practical use and compliance with relevant workplace health and safety standards. Eg. many photo luminescent paints rely on a white primer base coat, the second coat is a clear carrier with the photo luminescent pigment added . Many also require a clear protective coat, (very time consuming).

Simple 1 coat application (no primer on most substrates).

Fast drying formula - Superior pigment is 95% refined to extract impurities and leave a much more pH stable pigment.

Slight semi gloss makes for easy cleaning.

Superior hardness to exceed thousands of vehicle passes in traffic use.

Can be opened to traffic after 5 minutes unlike other photo luminescent paints which can take up to 1 hour and therefore unsuitable, if being applied to a road surface.

- Fine particle size of the pigment can be used to ensure no modifications need to be made to spray equipment.

- The lower specific gravity of the formula allows for less loading of photo luminescent which means considerable cost savings.

Superior UV stability and hard wearing.

A powered pigment or suitable liquid concentrate or nano particle/sub micron dispersion allows for easy integration into the formula. " High volume , low pressure sprayers can be used when applying a paint composition with luminous particles added. If the luminous particles are of a larger size (say 50-65 microns) the tendency when high pressure is used is for the water in the formula to be distributed first, leaving the luminous particles to often clog the tip of the sprayer.

In the present specification and claims, the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims

CLAIMS:

1. A paint composition having luminescent qualities when applied and dried, said composition including a latex resin material, at least one solvent material including at least one coalescing solvent, at least one pigment containing particles of luminescent material, wherein the composition maintains a viscosity suitable for both spray application and maintaining the particles in suspension while drying after application, the composition having a pH of between 7-12.

2. The composition of claim 1, wherein the composition is a road marking paint.

3. The composition of any one of the preceding claims wherein the pH is compatible between the luminescent pigment and the paint composition.

4. The composition of any one of the preceding claims, wherein the pH is between 7.5-12.

5. The composition of any one of the preceding claims wherein the latex resin material comprises an acrylic resin..

6. The composition of any one of the preceding claims, wherein the coalescing solvent is 2,2,4-trimethyl-l,3-pentanediol mono-isobutyrate.

7. The composition of any one of the preceding claims, wherein the pigment comprises the pigment described in Table 1 of the patent specification.

8. The composition of any one of the preceding claims, wherein the amount of pigment comprises approximately 10%-20% by weight.

9. A method for formulating a paint composition having luminescent qualities when applied and dried, said composition including a latex resin material, at least one solvent material including at least one coalescing solvent, at least one pigment containing particles of luminescent material, the method including the steps of forming a latex paint base by adding a solvent to the latex resin material and mixing, subsequently adding an amount of water, followed by addition of the at least one pigment and mixing, the pH of the composition being between 7-12.

10. A road marking paint composition comprising an aqueous acrylic resin, and a pigment containing particles of luminescent material, the composition having a pH of greater than 7 and typically between 9-12.

11. The composition of claim 10 wherein the pH is between 7.5-12.

12. The composition of claim 1 l,wherein the pH is between 7.5-12.

13. A paint composition substantially as hereinbefore described.