AU2005100861B4 - Retroreflective Composition - Google Patents
Retroreflective Composition Download PDFInfo
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- AU2005100861B4 AU2005100861B4 AU2005100861A AU2005100861A AU2005100861B4 AU 2005100861 B4 AU2005100861 B4 AU 2005100861B4 AU 2005100861 A AU2005100861 A AU 2005100861A AU 2005100861 A AU2005100861 A AU 2005100861A AU 2005100861 B4 AU2005100861 B4 AU 2005100861B4
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- AU
- Australia
- Prior art keywords
- composition
- beads
- retroreflective
- binder
- aluminium
- Prior art date
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Description
AUSTRALIA
ORIGINAL
COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Name of Applicant: Actual Inventor(s): Address for service: Retroreflective Composition Timothy John Smart Timothy John Smart WRAY ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR The following statement is a full description of this invention, including the best method of performing it known to me:- -2-
O
C< "Retroreflective Composition" Field of the Invention 00 The present invention relates to a retroreflective composition. More particularly, the composition of the present invention is intended to be applied to the surface of -0 00 5 objects to increase their visibility at night or in conditions of low or no light by the retroreflection of incident light.
SBackground Art Traffic control devices such as road markings are known to communicate important information to users. At night and in conditions of limited visibility, such information must be visible to road users.
Retroreflectivity is a type of reflection that directs light back towards its source. If an observer is close to said light source, a retroreflective target appears brighter than a non-retroreflective target.
Prior art examples of retroreflective surface comprise the application of layers of glass beads of the same diameter onto the surface wetted for example with a paint.
On drying of the paint, the beads adhere to the surface. The refractive index of glass beads with air is such that they are more transparent than reflective and in order to get reflective properties, they need to be embedded in something with a different index. Having the beads embedded to about half their diameter is believed to provide the greatest retroreflectivity.
To maximise retroreflectivity and embed the beads to the preferred depth, it is necessary to strictly control the depth of the paint prior to adding the beads which can be problematic in many instances, not the least of which is having to apply the paint and beads in two layers.
The present invention has as one object thereof to overcome substantially, or at least provide a useful alternative to, the above-mentioned problems associated with the prior art.
3/1 N The preceding discussion of the background to the invention is intended to facilitate >an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgement that any material referred to was part of the common general knowledge in Australia as at the priority date of the application.
Throughout the specification, unless the context requires otherwise, the word N"comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.
C Disclosure of the Invention In accordance with the present invention, there is provided a retroreflective composition adapted to be applied as an aerosol to a surface, the composition comprising a plurality of substantially spherical beads of various sizes, a binder and a liquid vehicle for delivery of the composition to the surface and a dispersant to reduce agglomeration of said beads in the composition prior to delivery of the composition to the surface, wherein the spherical beads comprise a reflective surface of aluminium and the beads are provided in a range of diameters between about 20 pm and about 100 pm.
In accordance with the present invention, there is provided a retroreflective composition adapted to be applied as an aerosol to a surface, the composition comprising a plurality of substantially spherical beads of various sizes, a binder and a liquid vehicle for delivery of the composition to the surface and an anti-settling agent adapted to reduce settling of said beads in the composition prior to delivery of the composition to the surface, wherein the spherical beads comprise a reflective surface of aluminium and the beads and are provided in a range of diameters between about 20 pm and about 100 pm.
In accordance with the present invention, there is provided a retroreflective coating, the coating comprising a plurality of substantially spherical beads of various sizes and a binder, wherein the spherical beads comprise a reflective surface of aluminium and the beads are provided in a range of diameters between about 20 pm and about 100 pm.
IND -3/2-
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CI Advantageously, the use of spherical beads with a range of diameters between Sabout 20 pm and about 100 pm is believed to provide the composition with greater retroreflectivity that a composition where the beads are all the same diameter.
Without being limited by theory, it is believed that this observation results from the smaller beads substantially filling in the spaces between the larger beads thereby providing a greater retroreflective surface.
IND
00 Advantageously, substantially spherical beads are not sensitive to the orientation of VI/ the beads, providing retroreflectivity from all directions.
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Without being limited by theory, it is believed that the use of beads with a reflective Ssurface advantageously avoids the strict requirement of the prior art glass beads that the beads be embedded about half way into the surface of the binder to maximize 00 retroreflectivity.
The skilled addressee will appreciate that the substantially spherical beads may IDcomprise a reflective surface over any material able to withstand the pressures 00 oO applied to the beads depending on the application, which may be application to the surface of a road.
C Preferably, the reflective surface of the beads is a metallic surface and more preferably, an aluminium surface. Where the beads comprise an aluminium surface, the aluminium surface preferably covers about half of the surface of each bead.
Preferably, the thickness of the aluminium coating is about 1 um.
Preferably, the beads comprise between about 20 to about 80 of the composition. More preferably, the beads comprise between about 30 to about 50 of the composition.
The liquid vehicle is adapted to carry the beads and the binder to the surface of the article to be coated with the retroreflective coating. It should be appreciated that the choice of vehicle will affect the flow of the composition during and after application and should be chosen to optimise the final appearance of the coating. The liquid vehicle is intended to evaporate after application to the surface, to leave a retroreflective coating comprising the beads and the binder.
Without being limited by theory, it is believed that where there is a higher proportion of larger beads, the vehicle should evaporate quicker than where there is a higher proportion of smaller beads to reduce sagging.
The choice of liquid vehicle will depend on the nature of the application and the size of beads and the properties of the binder. The liquid vehicle assists in controlling the penetration of the beads in the resin and controlling shrinkage of the resin on evaporation of the vehicle.
O The liquid vehicle should preferably dissolve the resin and may be provided in the Sform of at least one aliphatic or aromatic solvent and may comprise a mixture of solvents O and may be selected from hydrocarbons, alkanes, alkenes, alkynes, alcohols, ketones, esters, aldehydes, aromatics, petroleum distillates. In preferred forms of the invention, the liquid vehicles may be selected from the group comprising toluene, acetone, ethanol, pentanes and hexanes.
IN
0 The skilled addressee will appreciate that the relative amount of liquid vehicle used _in the composition will depend on the final application of the composition as well as the nature and amount of the binder and the amount of spherical beads in the composition, although it is expected that the composition will comprise between about 5 to about 80 liquid vehicle and more preferably and more preferably between about 40 to about 60 liquid vehicle.
The binder is a transparent or translucent non-volatile material and is adapted to adhere to the surface of the article to be coated with the retroreflective coating and to retain the beads on said surface. It should be appreciated that the choice of binder will affect the flow of the composition during application and should be chosen to optimise the final appearance and strength of the coating as well as other properties of the coating such as adhesion, gloss level, hardness, abrasion resistance, flexibility, speed of drying and durability.
The choice of binder will depend on the nature of the application and the size of beads. The amount of binder used in any composition will be influenced by the amount of beads used as the binder should not cover the beads in coating when in use.
Investigations suggest that as the proportion of binder increases, better adherence of the coating to the article surface is provided. However, if the binder covers the surface of the beads, retroreflectivity may be reduced, depending on the transparency of the binder.
It should be appreciated that the skilled addressee will realise that the choice of binder will depend on the final application of retroreflective composition as well as the range of bead sizes.
-6- O The binder may be selected from the group comprising acrylic polymers or copolymers, enamels, polyeurethanes, epoxy resins, silicone based resins and acrylic o resins.
Preferably, the resin comprises between about 10 to about 40 of the composition.
IND (0 0The skilled addressee will appreciate that the efficacy of the composition will be increased by the addition of additives known in the art such as dispersants, antisettling agents, stabilising agents to enhance long-term storage, wetting and Sdispersing agents to assist wetting and dispersion of the beads, drying and curing agents improve and control the drying properties of the composition, enhancers, pigments, anti-mould and anti-marring agents, anti-foaming agents to minimise foaming of the composition during manufacture or application to a surface, fragrances and insecticides.
It will be appreciated that where used, the additives should not interfere with the retro-reflectivity of the composition.
Where the composition is provided with an anti-settling agent, the anti-settling agent may be provided in the form of a fumed silica such as that sold under the AEROSIL trade mark by Degussa AG, such as Aerosil R972. It should be appreciated that where the composition comprises a fumed silica, the choice of fumed silica type and grade will affect the rheological and surface characteristics of the composition.
Alternatively, the anti-settling agent may be provided in the form of Disperbyk®-410 (registered TM of Altana Pharma AG), a liquid rheological additive.
The anti-settling agent acts to retain an even distribution of the beads throughout the composition and may comprise between about 0.1 to about 10 of the composition. It will be appreciated that the greater the proportion of beads in the composition, a greater proportion of sediment inhibitor is required.
Where the composition is provided with a dispersing agent, the dispersing agent may be provided in the form of Disperbyk®-103 (registered TM of Altana Pharma AG). Without being limited by theory, it is believed that the high molecular weight -7- O additive deflocculates particles through steric stabilisation of said particles.
SDeflocculation is believed to increase transparency and gloss of the composition.
0 The dispersing agent may comprise between about 0.1 to about 10 of the composition.
ID 5 The composition may further comprise pigments as known in the art. Where oO 0provided, it is expected that the pigments will comprise between about 1 to about 2 of the composition. Alternatively, the beads may be coated with a transparent or substantially transparent coating to provide pigmentation. The coating may be Sapplied to the surface of the beads by for example, anodising. Alternatively, the retroreflective coating may be further coated with a tinting agent.
The composition of the present invention may be applied to a surface by any means known in the art including painting with sprays cans, spray guns or brushes.
Where the composition is applied to a surface by spray can or spray gun, the composition may further comprise a propellant. The skilled addressee will appreciate that any suitable propellant known in the art may be used to propel the composition from the can or gun. The propellant may be selected from the group comprising dimethyl ether or a mixture of propane and butane. Where the propellant is provided in the form of a mixture of propane and butane, the mixture preferably comprises 10 propane and 90 butane.
The composition may preferably comprise a blending agent to assist blending of the composition with the propellant. An example of a suitable blending agent is ethylene glycol butyl ether.
In accordance with the present invention, there is provided a retroreflective composition adapted to be applied to a surface from a spray can, the composition comprising a plurality of substantially spherical beads with a range of diameters, a binder in the form of a acrylate resin, a liquid vehicle for delivery of the composition to the surface, adapted to evaporate from the surface after application, a propellant, a dispersant adapted to reduce agglomeration of said beads in the spray can, S-8-
NO
0 wherein the spherical beads comprise an aluminium surface and are provided in a ;range of diameters between about 20 pm and about 100 pm.
00 Brief Description of the Drawings 0 The present invention will now be described, by way of example only, with reference NO 5 to two embodiments thereof and the accompanying Figure, in which:- 00 SFigure 1 is a schematic drawing depicting entrance angles and observation angles for retroreflectivity tests.
Best Mode(s) for Carrying Out the Invention By way of example, the method of the present invention is described in the context of a retroreflective paint for application under pressure with a spray can, although such should not be seen as limiting the generality of the foregoing description.
Two embodiments of the present invention will now be described with reference to a retroreflective composition for application to a surface as an aerosol. It is to be understood that these embodiments are detailed by way of example and are not to be considered limiting.
Examples In one embodiment of the invention, resin in the form of Paraloid® B66 (32.5 a thermoplastic acrylate from Rohm and Haas Company, USA was added to a solution of Recosol® VB thinners from Recochem Inc. a mixture of aromatic hydrocarbons, short chain ketones and low boiling fractions of petroleum, mainly pentanes and hexanes (32.5 The resin/solvent mixture was then diluted with further Recosol® VB thinners (80 Disperbyk®-103 (registered TM of Altana Pharma AG (1 g), Disperbyk®-410 (registered TM of Altana Pharma AG (1.5 g) were added to the mixture followed by aluminium coated glass beads (70 g) with a refractive index of 1.93.
The aluminium coated glass beads were provided in a range of particle sizes, approximately 6 of beads of diameter 30 pm, 31 pm, 32 pm, 33 pm, 34 pm, -9pm, 36 pm, 37 pm, 38 pm, 39 pm, 40 pm, 41 pm, 42 pm, 43 pm, 44 pm and pm.
c The composition was then added to a conventional spray can under pressurised with either propane/butane propellant 130 g) or dimethyl ether propellant (130 g).
Where the propellant is provided in the form of dimethyl ether, the composition will 00 preferably further comprise ethylene glycol butyl ether to assist the blending of the composition with the propellant.
SWhere the composition is applied to a surface as an aerosol from a spray can, the can should be well shaken before use. Without being limited by theory, it is believed that the use of sediment inhibitor reduces settling of the composition in the can and avoids the need to continuously shake the can whilst in use.
In use, the composition may be applied from the pressurised spray can in the conventional manner. Preferably, the can is held 20 30 cm from the surface and sprayed once or twice. The surface may be resprayed after 3 5 min. On evaporation of the liquid vehicle, the composition contracts resulting in apparent shrinkage of the resin exposing the surface of the beads to incident light. Where the composition is applied to a porous surface, it is believed that, depending on the porosity of the surface, the resin may be drawn into the surface in preference to at least a portion of the beads, thereby exposing the beads to incident light.
To test the properties of the composition of the present invention, and in order to replicate the use of the composition on a horizontal surface such as a road, the retroreflectivity of a sample was measured with a MX30 retroreflectometer (available from Potters Europe, an affiliate of The PQ Corporation) and the results shown below in Table 1. The sample was prepared in accordance with the examples, using dimethyl ether as the propellant. The composition was sprayed onto a sample of galvanised tin plate and over-sprayed a further four times.
As represented in Figure 1, the test is designed to replicate the shining of light from, for example, a car headlight onto a road surface, the light being reflected back into the car driver's eyes. Referring to Figure 1, light 10 is transmitted from a light source O 12 such as a headlight on a car onto a road surface 14 painted with a retroreflective C coating 16. The entrance angle 18 of the light 10 is the angle between the light 0 source 12 and the perpendicular 20 to the road surface 14. The reflected light 22 is
O
reflected back to the observer 24 at the observation angle 26, the angle between the light source 12 and the observer 24.
O
O
I
Entrance Angle Observation Angle 88.760 1.05 Retroreflectivity (millicandela per lux per square meter) 1015 Table 1.
In order to test the efficacy of the composition of the present invention as a coating for street signs, conventionally displaced substantially vertically, tests in accordance with Australian Standard AS/NZS1906.1 were performed and the results shown in Table 2. AS can be seen from the results in Tables 1 and 2, the composition of the present invention provides an efficient retroreflective coating and given its ability to be applied in similar fashion to paints, it consequently has a wide range of industrial uses.
Entrance Angle 4° 15° 300 Observation Angle 0.2 0.33 1. 0.2 0.33 0.2 0.330 1.0 Retroreflectivity 31.6 26.1 6.7 31.0 25.6 .4 27.7 22.9 Table 2. Retroreflectivity Photometer (vertical) CIL/m2 (candela per lux per square meter) (Rotational variance at 150/0.20 It will be appreciated that the composition of the present invention may be applied to any surface where the retroreflective properties of the composition would be advantageous. Such surfaces are known to include roads, road signs, fence posts, railings, gates, parts of vehicles such as cars and trucks and in particular, bumper -11 o bars, parts of boats, push bikes and motor bikes, helmets, mining equipment and in Sparticular, underground mining equipment, house numbers, trees, rocks and in 0 particular, those near roads and driveways, clothing, shoes and bags.
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Claims (4)
1. A retroreflective composition adapted to be applied as an aerosol to a surface, the composition comprising a plurality of substantially spherical beads of various sizes, a binder and a liquid vehicle for delivery of the composition to the surface and a dispersant adapted to reduce agglomeration of said beads in 1 ~the composition prior to delivery of the composition to the surface, wherein the spherical beads comprise a reflective surface of aluminium and the beads and are provided in a range of diameters between about 20 pm and about 100 pm. I/3 C
2. A retroreflective composition adapted to be applied as an aerosol to a surface, the composition comprising a plurality of substantially spherical beads of various sizes, a binder and a liquid vehicle for delivery of the composition to the surface and an anti-settling agent adapted to reduce settling of said beads in the composition prior to delivery of the composition to the surface, wherein the spherical beads comprise a reflective surface of aluminium and the beads and are provided in a range of diameters between about 20 pm and about 100 pm.
3. A retroreflective composition adapted to be applied as an aerosol to a surface, the composition comprising a plurality of substantially spherical beads of various sizes, a binder in the form of an acrylate resin, a liquid vehicle for delivery of the composition to the surface, wherein the liquid vehicle is adapted to evaporate from the surface after application, a propellant, a dispersant adapted to reduce agglomeration of said beads in the spray can, wherein the spherical beads comprise a reflective surface of aluminium and the beads are provided in a range of diameters between about 20 pm and about 100 pm.
4. A retroreflective composition according to claim 1 or claim 2, wherein the beads are glass beads and the reflective surface is an aluminium coating on the beads wherein the aluminium coating covers approximately half of the surface of each bead. -13- A retroreflective composition substantially as herein described, with reference to the Examples. Dated this First day of May 2006. IO Timothy John Smart 00 Applicant SWray Associates Perth, Western Australia C- Patent Attorneys for the Applicant
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2005100861A AU2005100861B4 (en) | 2004-10-12 | 2005-10-12 | Retroreflective Composition |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2004905855 | 2004-10-12 | ||
| AU2004905855A AU2004905855A0 (en) | 2004-10-12 | Liquid reflector (a reflective coating for safety) | |
| AU2005100861A AU2005100861B4 (en) | 2004-10-12 | 2005-10-12 | Retroreflective Composition |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2005100861A4 AU2005100861A4 (en) | 2005-11-17 |
| AU2005100861B4 true AU2005100861B4 (en) | 2006-05-18 |
Family
ID=35455837
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2005100861A Expired AU2005100861B4 (en) | 2004-10-12 | 2005-10-12 | Retroreflective Composition |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU2005100861B4 (en) |
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2005
- 2005-10-12 AU AU2005100861A patent/AU2005100861B4/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU2005100861A4 (en) | 2005-11-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FGI | Letters patent sealed or granted (innovation patent) | ||
| MK22 | Patent ceased section 143a(d), or expired - non payment of renewal fee or expiry |