EP0005376B1

EP0005376B1 - Method for making decorative emblems

Info

Publication number: EP0005376B1
Application number: EP19790300786
Authority: EP
Inventors: Robert E. Waugh
Original assignee: DL Auld Co
Current assignee: DL Auld Co
Priority date: 1978-05-08
Filing date: 1979-05-08
Publication date: 1985-08-14
Also published as: EP0005376A1; IE50566B1; IE790925L; JPS54146838A; DE2967497D1

Description

The present invention relates to a method for making decorative emblems or plaques, which have a cured plastic layer over a decorative surface and, more particularly, it relates to a method for flow coating a fluent plastic material onto a decorative substrate to give a uniform thickness coated substrate from which emblems or plaques are formed.
Decorative plaques and emblems are widely used throughout a number of industries, including the automotive and appliance fields. In the past, a colored vitreous frit was flowed into a bronze substrate and fired at 1250°F (676°C). The glass-like vitreous enamel served to beautify the product and protect the decorative substrate from weathering should the plaque or emblem be exposed to the environment.
Today, plastics are primarily used for producing such plaques and emblems. For example, in Loew (U.S. Patent No. 3,654,062), there is disclosed a process for injection molding a decorative Mylar facing sheet over a vinyl plastic body. The plaque is coated with a layer of protective varnish on the outer surface of the facing sheet. Gits, U.S. Patent No. 3,246,066, is similar in that male and female molds are used to form a cavity into which a decorative foil is placed and into which a clear plastic material is injected. Prior to injecting a clear plastic material against the front face of the foil, the foil is precoated. Other molding processes, such as compression molding (either one or two shot), are also well known in the art. See for instance, U.S. Patents No. 2,244,565; 2,931,119; 3,075,249; and 3,114,597.
In U.S. Patent No. 4,100,010 there is disclosed an improved process for producing decorative emblems. That process involves casting a plastic material onto decorative foil shapes to form a meniscus which when cured gives a lens effect to the top surface of the foil shape. A problem with that process is that the foil shapes are cast individually and the manufacturing process can as a result be too cumbersome and costly for some purposes. Accordingly, the need exists for yet another improved process for producing decorative emblems which is less expensive and more efficient.
The present invention meets that need by utilizing a flow coating process to apply a clear plastic material to a decorative substrate from which individual emblems and plaques may then be stamped and.shaped. Of course, flow coating per se is known in a number of areas.
U.S. Patent No. 4,034,708 discloses such a process for coating glass containers. As another example, U.S. Patents No. 3,875,893 to Riley and 3,431,889 to Fraatz both disclose flow-coating processes using multiple orifices to lay down a thin film onto a flat surface. But Fraatz and Riley do not relate to emblem or plaque manufacturing processes where a clear plastic is applied to a decorative substrate.
It should also be noted that Hansen in U.S. Patent No. 3,725,112 mentions flow coating as one of the possible methods for producing his coated or encapsulating substrates. That patent discloses applying a protective low-glare, uniformly textured, transparent, polymeric coating to a substrate such as wood, steel, hardboard, aluminum and the like. Still, the intent of Hansen is to produce textured films having a low-glare surface and not to produce decorative emblems of the type contemplated by the present invention.
Therefore, the need still remains for a method for flowing coating clear plastic materials onto a decorative substrate to economically and efficiently produce decorative emblems or plaques.
The present invention utilizes such a flow coating process to produce decorative emblems in a manner more conducive to mass production than the process of U.S. Patent No: 4,100,010. Of course, the depth and beauty of the lens effect achieved by the process of that patent is not duplicated with the present process. Still, it does have a number of other advantages. Principal among these is the economical and efficient means of production by applying a smooth plastic coating to a decorated substrate having a series of designs which are subsequently cut out and formed to a slightly convex shape by a die-cutting operation.
The plastic is of a more flexible variety and is applied in a thinner film which will withstand the subsequent shaping operation. And yet, because it is possible with the instant flow coating process to deposit the plastic on the decorative substrate uniformly to a thickness of .020 to .030 inches (.508 to .762 mm), an attractive emblem is still produced.
The substrate upon which the fluent plastic is coated may be a plastic or metal foil, preferably an aluminium foil 0.003 to .020 inch (.0762 to .508 mm) thick. The foil substrate is decorated with a series of designs in the form of individual emblems or plaque shapes applied to the foil sheet. With a metal foil, the series of designs is preferably applied by silk screen or lithographic printing then the design is enhanced by embossing selected areas; although, other means for forming the decorative designs may also be used.
Likewise, it is desirable to prime the top surface of the substrate prior to printing. Any suitable primer may be used such as a silane primer. The decorated-primed substrate is then placed upon a vacuum mat which is situated upon a horizontal vacuum table such as that shown in U.S. Patent No. 4,034,708. Vacuum is drawn against the bottom surface of the foil through the mat to hold the substrate flat and horizontal.
It is important that the substrate be held flat and horizontal during flow coating because of the fact that the flow characteristics of the fluent plastic and the liquid wettability of the substrate are used to control the spread of the plastic so that it is contiguous with predetermined areas of the foil as well as being uniformly thick. Another important factor in controlling this is the existence of sharply defined peripheral sides for the substrate or define areas of the substrate.
Thus, it is possible to limit the coated areas of a single foil sheet by forming slits, embossed ridges, or other sharp edges in the sheet. When a predetermined amount of fluent plastic is flow coated onto that area, then, it will spread only to the sharply defined peripheral side. In this manner, it is possible to avoid waste by coating only the path directly over the designs from which the emblems or plaques are to be formed, and not wastefully on peripheral areas which are to be discarded.
In the present invention, the flow coating is a pathwise disposition. That is, a multiple orifice nozzle (or nozzles) is passed over the decorated-primed surface of the foil at a steady speed as the substrate is held stationary. The number of orifices used may vary depending on the width of the path to be laid down. As. an example, a 2.1 inch (53.34 mm) wide nozzle having 22 orifices of a .022 inch (.5588 mm) I.D. and with a 0.10 inch (2.54 mm) spacing between the orifices, can be used to lay down a path of 2.4 to 2.5 inches (60.96 to 63.5 mm) in width.
As can be seen from this example, if such a nozzle is to be used to coat a sheet of greater than 2.5 inches (63.5 mm) width, then either several nozzles tracking across the sheet in parallel paths must be used or the single nozzle must be programmed to track back and forth across the sheet until the surface is covered with a uniform thickness of the fluent plastic.
The thickness sought is between approximately .020 to .030 inch (.508 to .762 mm). The plastic is preferably a fluent polyurethane of two component parts (polyol and isocyanate) which are mixed immediately prior to coating and cure upon heating. A polyurethane of this type is disclosed in U.S. Patent No. 4,100,010. In formulating the particular plastic composition from among those disclosed in said Patent, it is important to use a catalyst which results in a somewhat slow curing time in order to allow the flow coated liquid plastic to flow to its full extent, i.e., to the sharply defined peripheral sides, before curing is accomplished. Otherwise, it may not be possible to obtain a uniform thickness, smooth coating.
Likewise, the polyurethane may be compounded from among the components listed in said Patent as is known to give a more flexible cured plastic. As long as the bond to the substrate remains strong, it is desirable in this invention to have a somewhat flexible plastic coat.
For most of the types of plastic contemplated curing will be by irradiation with infra-red or ultraviolet light. The polyurethane compounds mentioned above are heat curable and, thus, infra-red lamps are used; although, obviously other heat sources may also be used. Still, it is desirable to get a thorough cure, i.e., heat from both the top and bottom of the coated foil. The preferred vacuum table arrangement of U.S. Patent No. 4,034,708 makes this possible because of a capability of heating or cooling it. However, it has been found desirable to use the infra-red lamps themselves as the heat source for both top and bottom heating. This may be done by using an I.R. absorptive mat as the vacuum mat. The mat will, then, pick up heat from the infra-red radiation and conduct it back from the bottom through the coated foil.
After curing, the coated substrate is cooled and removed from the vacuum table. It is at this stage that the individual emblem or plaque shapes contained on the single sheet are stamped out by a cutting die around the particular emblem or plaque shape. It has been found that by die cutting from the bottom surface of the coated foil, it is possible to impart a slightly convex configuration when viewed from the top surface. The convex shape helps to give the appearance of a lens effect to the emblem; although a lens does not actually exist.
Still, the appearance of the coated emblem is superior to a non-coated one. The luster and beauty of the clear plastic adds considerably to the appearance. It also serves to protect the decorative surface from weathering, chipping, scratching, etc.
The present invention will now be more fully described with reference to the accompanying drawings, in which:-

Fig. 1 is a perspective overall view of the preferred apparatus for performing the method of the present invention;
Fig. 2 is a side view of the device;
Fig. 3 is a view illustrating the coating nozzle arrangement for performing the method of the present invention;
Fig. 4 is a perspective view of the coating arrangement for performing the method of the present invention; and
Fig. 5 is a cross-sectional view of the coated sheet of Fig. 4.

The flow coating process of this invention may be performed with a modified form of the device disclosed in U.S. Patent No. 4,034,708. An overall view of that device is shown in Fig. 1. As seen there, a foil substrate 12 having a series of emblem design shapes 82 decorated on its surface is positioned on vacuum table 14.
The coating operation utilizes a casting head (not shown in Figs. 1-2) in the form of a multiple orifice nozzle or nozzles (see Figs. 3-4) for flow coating measured amounts of a fluent plastic material, such as a fluent polyurethane, to the upper surface of the substrate 12.
Preferred are approximately 100% solid polyurethane resin systems which are catalyzed by mixing two components just prior to casting. In order to promote a rapid curing of the fluent polyurethane system, an infra-red radiation source means for supplying infra-red radiation may be provided to irradiate the polyurethane. Such a source is included in member 20 which is shown extended in Fig. 1 in dashed lines.
In the arrangement illustrated in Figs. 1-2, the source of radiation is moved rather than moving the substrate; although, the reverse situation can also be used. The extended position of the member 20 is shown also in Fig. 2, along with lamps 23 which provide the infra-red radiation. Member 20 is moved by means of air cylinder 25. It should be understood that an ultraviolet curable plastic may also be cast using the apparatus of the present invention; in such a case, lamps 23 would be ultraviolet radiation sources.
While only very small amounts of volatiles will be given off by the plastic during curing, an exhaust means including blower 29, exhaust duct 30, and associated motor (not shown) are provided in order to ensure that the operator of the machine does not inhale fumes unnecessarily. As illustrated in Fig. 2, ambient air is drawn into the cabinet 31 by fan 29. The air will be drawn over the top of the platen means 35. The air will also be drawn past the lamps 23 preventing fumes from escaping upwardly through member 20 and also cooling lamps 23.
It may be desirable to control the temperature of the substrate prior to and during the casting and curing process. Under some circumstances, it may be desirable to maintain the substrate at one temperature during casting and a portion of the curing process, and then to maintain the substrate at a second temperature. Toward this end, water inlets 36 and 37 and one or more outlets 38, are provided to receive and discharge water supplied at more than one temperature.
It may also be desirable to irradiate the substrate prior to the casting process, such that the substrates are heated and the viscosity of the cast plastic reduced as it flows onto the substrates. This reduction in viscosity will cause the plastic to flow more evenly over a larger foil substrate. Since it is desirable to be able to change readily the sequence of steps and the order of these steps, a number of timers and controls shown generally at 39 are provided. Vacuum pump 41 is also provided to supply a vacuum platen 35 with a vacuum.
The use of a vacuum to hold substrate 12 flat and horizontal is better shown in Fig. 3. Thus, vacuum pump 41 draws a vacuum through holes 43 in platen 35. This serves to hold vacuum mat 45 onto the platen since the holes in vacuum mat 45 are not aligned with those in platen 35. The vacuum mat 45 may be a perforated one-fourth inch (6.35 mm) thick silicone rubber mat. Since it is perforated, the vacuum from platen 35 will also be drawn through mat 45 against substrate 12.
Fig. 3 also shows in detail casting head 47 having two nozzles 49 and 50. Each nozzle is fed a supply of fluent plastic such as a liquid polyurethane. Preferred is a mixture of "A" and "B" components of the type disclosed in U.S. Patent No. 4,100,010. Basically, that mixture is one of a polyether polyol component ("A"), which may be a difunctional, trifunctional and/or tetrafunctional polypropylene glycol containing a suitable catalyst, and a diisocyanate component ("B") such as an aliphatic diisocyanate. A catalyst such as a lead material is used since it promotes a slow cure at room temperature so as to allow time for full flow of the liquid polyurethane before setting. An example of the diisocyanate is Hylene W from E.I. duPont de Nemours and Co., and the polyether polyol may be one or more of the Pluracol materials (P-410 or TP-440) from BASF Wyan- dotte. It may also be a polyether-polyester polyol combination, use of the polyester polyol making the cured polyurethane more flexible. The ratio of components A: B is preferably 50-60:40-50. A polyester polyol or polylactone polyol could be used in place of the polyether polyol.
The mixture of "A" and "B" components of this type cures, through catalytic action, under heat such as produced by infra-red radiation. Accordingly, this type of mixture is preferred; although, single component, photocurable, polyurethanes of known types could also be used.
Tanks (not shown) store the "A" and "B" material separately prior to mixing, then, feeding to supply lines 51 and 52 for nozzles 49 and 50. Nozzles 49 and 50 are mounted on carriage 54 which is slidably mounted on rods 57 and 58 for motion over the surface of substrate 12 as indicated by the arrows in Fig. 4. Each nozzle has multiple orifices in the form of tubes 61 and 62. Fittings 63 and 64 connect each of the multiple orifice nozzles 49 and 50 to supply lines 51 and 52.
The number of tubes 61, 62 and the spacing between the tubes in an individual nozzle will vary in dependence on the width of the portion of the substrate to be coated. It has been found, however; that between 10 and 26 tubes, spaced apart approximately 1/8 and 1/10 inch (3.175 to 2.54 mm), may be used for each nozzle means in the present embodiment. The tubes preferably have .022 inch (.5588 mm) I.D. and a .039 inch (.9906 mm) O.D. Spacer bars 71 and 72 hold the tubes 61 and 62 spaced apart at desired distances, preferably 0.10 inch (2.54 mm). For application of a uniform thickness coating across each of the two zones of approximately 2.4-2.5 inches (60.96-63.5 mm) in width each, 22 tubes are used in each nozzle 49 and 50. The 22 tubes have a combined width of approximately 2.1 inches (53.34 mm).
The operation of casting head 47 is better understood with reference to Fig. 4. Pneumatic or hydraulic controls (not shown) drive casting head along the length of stationary substrate 12 as indicated by the arrows. A return movement, also as indicated, takes place after completion of flow coating onto one decorative substrate and the casting head is in position to repeat the process for another decorative substrate. As the casting head 47 begins its initial track over substrate 12, starting at approximately 0.15 to 0.20 inch (3.81 to 5.08 mm) from the edge 75, the liquid polyurethane flows from tubes 61, 62 at a uniform flow rate. Since the movement of casting head 47 over stationary substrate 12 is at a steady speed, there is laid down a uniformly distributed amount of liquid polyurethane.
That fluent plastic then flows to complete the coverage of the portion of the surface desired. A uniform thickness of plastic results. The speed of casting head movement and coating rate for the plastic depend upon the area to be covered, the number of tubes used, the viscosity of the fluent plastic, etc. Generally, however, it is possible to easily adjust these variables in order to achieve a coating of the thickness desired. The desired thickness is 0.020 to 0.030 inch (.508 to .762 mm).
As mentioned, an important feature in obtaining a uniform coating in this thickness is that the fluent plastic on the surface of substrate 12 flows up to, but not beyond, the sharply defined peripheral sides which intersect with the planar top surface.
Thus, the wettability characteristics of the fluent plastic are such that it only partially wets the surface of substrate 12 and will flow on the surface of the substrate. Under heating, the viscosity of the polyurethane becomes lower and flow slows. Upon reaching a sharply defined peripheral side, this flow will be halted. If the edge is vertical, the flowing liquid plastic wants to maintain a given angle at the edge (specified by the interface properties of the plastic and the foil). As long as the internal pressure (hydrostatic) of the plastic does not exceed the surface tension at that contact angle, the liquid plastic will not overflow the side.
Accordingly, it is necessary to form sharply defined peripheral sides intersecting with the top planar surface around each area to be coated. In Fig. 4, there are two paths which are to..be uniformly coated, one beneath nozzle 49 and one beneath nozzle 50. The line between these paths is slit 77 which forms sharp peripheral sides 79 and 80. The ordinary four edges of substrate 12, then, complete the formation of the two paths. Of course, other arrangements may be used to form the sharply defined peripheral sides, such as by embossing ridges in the sheet.
It is also possible to coat the whole surface of substrate 12 since its four edges are sharply vertical. However, it may be advantageous in terms of eliminating excess scrap and waste to form paths in the manner mentioned. Those paths, then, will be over only those areas of the substrate from which emblems or plaques are to be formed.
In Figs. 4-5, those emblems are represented by emblem design shapes 82. It is desirable to prime the substrate with a silane before printing. As an example, a mixture of approximately 2% castor oil (Surfactol from The Baker Castor Oil Co.) and up to approximately 2% silane (Dow 6020, 6040, or 6075 from Dow Corning Corp., which are respectively 3-(2-aminoethylamine) propyltrimethoxysilane, glycidoxypropyltrimethoxysilane, and vinyltriacetooxysilane) in a solvent (70% isopropyl alcohol and 30% octane) may be used. Other known silane primers may also be used. The primers may be pre-applied by spraying, dipping, or roller-coating, followed by drying to remove the solvent.
Next, the design shapes are decorated onto substrate 12. With a metal foil, silk-screen printing and embossing are the usual methods. Thus, an aluminium foil from 0.003 to 0.020 inch (0.0762 to 0.508 mm) thick may be silk-screen printed and embossed in selected areas to provide a series of emblem design shapes as at 82.
The fluent plastic is then flow coated onto the substrate 12 as described. Next, the substrate is heated with infra-red lamps 23, also as described, in order to cure the plastic.
A feature of the present invention is the use of vacuum mat 45 to aid in that curing process. That is, by using an infra-red absorptive mat, such as a one-fourth inch (6.35 mm) thick silicone rubber mat, heat is absorbed by the mat and re-radiated back through substrate 12 to give a thorough cure.
Once the curing is accomplished and the coated substrate cooled, plastic layer 84 is adhered to substrate 12 sufficiently to permit further processing. A die is used to cut around each emblem design shape 82 to form individual emblems. By die cutting from the bottom (uncoated) side 86 of substrate 12, a slight convex shape is given to each emblem.
The emblems may then be adhesively applied into or onto the intended surface. They may also be placed in a retaining frame which is used to affix the emblem onto the surface. Finally, it is noted that since the fluent plastic may be compounded as described to give a somewhat flexible material when cured, forming other than merely die cutting may be undertaken. The emblem may be conformed to non-planar surfaces as long as the degree of bending for the conformity required is not too severe.
While the preferred embodiment just discussed utilizes a two-nozzle casting head as shown in Figs. 3-4 which makes a single pass over substrate 12, it should be emphasized that a single multiple orifice nozzle may be used for a narrower application path or additional nozzles may be added to casting head 47 to give a wider application path. Likewise, the number of tubes used with each nozzle may be varied to vary the width of the application path.
Another embodiment involves use of a single nozzle of the type shown for coverage of a substrate of varying widths. It is mounted on a carriage of the same width which only tracks back and forth longitudinally over the length of substrate 12. Also, the nozzle is movable laterally on the carriage. After each pass and on the return route, the nozzle moves laterally one nozzle width (plus approximately 0.15-0.20 inch (3.81-5.08 mm). Another pass begins. This is repeated until the full expanse of the substrate has been coated. In each case, a timing mechanism is necessary to start and stop flow of the liquid plastic during a single pass. A delay timer is provided to permit the lateral movement of the nozzle after the plastic flow has stopped and prior to the start of plastic flow after the lateral movement of the nozzle is completed.

Example

In this example, a single nozzle having 22 tubes as described was used to flow coat a substrate of approximately 2.5 inch x 24 inch (63.5 x 609.6 mm) in a single pass. The substrate was 0.015 inch (0.381 mm) thick aluminium foil which had been cleaned, primed, silk-screen printed and embossed with a series of circular emblem designs approximately 1 1/8 inch (28.575 mm) in diameter.
The 22 tube nozzle had a width of approximately 2.1 inches (53.34 mm) and was centered over the 2.5 inches (63.5 mm) wide substrate to leave margins of approximately 0.20 inch (5.08 mm). Starting 0.20 inch (5.08 mm) from one end of the foil, it was passed over the surface of the aluminium foil, which was held flat and horizontal on a vacuum mat as described. A steady speed of 3.2 inches (81.28 mm) per second was used. Clear liquid polyurethane was flowed from the nozzle at the uniform rate of 210 grams per minute.
The liquid polyurethane was a mixture of "A" and "B" components and had a density of 17.39 grams/cubic inch (1.06 grams per cubic centimeter). The "A" component was itself a mixture of polyester polyol and polyether polyol and contained a lead octoate catalyst. The "B" component was a mixture of polypropylene glycol and an aliphatic diisocyanate. The ratio of "A" to "B" was 54.5% to 45.5%.
It took the nozzle 7.43 seconds to transverse the 24 inch (609.6 mm) length of the aluminium foil (stopping 0.20 inch (5.08 mm) from the end). In the process, 26 grams of liquid polyurethane were deposited onto the foil at a uniform thickness of 0.025 inch ± .005 inch (0.635 mm ± 0.127 mm).
After flow coating, the coated foil was heated under four 1600 watt infra-red lamps at a distance of 12 inch (304.8 mm) for 10 minutes. This was followed by cooling the vacuum table with 60°F (15.55°C) water for 2 minutes. After cooling, representative ones of the emblem shapes were die cut from the foil by applying a die to the bottom (uncoated) surface of the foil.
The emblems had a slightly convex shape when viewed from the front surface, and were lustrous in appearance. The cured plastic was bound firmly to the decorative substrate and provides a tough, resistant protective coating in addition to beautifying the design.
While the method herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise method, and that changes may be made therein without departing from the scope of the invention.

Claims

1. A method of producing decorative emblems or plaques comprising flow-coating a clear, viscous, fluent plastic on to the top surface of a decorated foil substrate (12) while the substrate is held flat and horizontal on a support surface (14), and allowing or causing the fluent plastic coating to cure while maintaining the substrate flat and horizontal to bond the said coating to the substrate, characterized in that said top surface of the substrate (12) has a series of designs (82) and is flow-coated with the clear fluent plastic by means of multiple orifices (61, 62) which are passed over the top decorative surface of the substrate (12) at a steady speed to produce a uniform thickness coating of approximately 0.508 to 0.762 mm thick which does not overflow the edges of the substrate, and in that individual emblems or plaques are stamped out of the substrate having the cured plastic coating (84) thereon by application of a cutting die to the bottom surface of the substrate so as to cut contiguous with the shape of each individual design (82) of the series of designs and to impart a slightly convex shape to the top surface of each said emblem or plaque.

2. The method of claim 1 wherein said substrate (12) is approximately 0.003 to 0.020 inch (0.0762 to 0.508 mm) thick metal foil.

3. The method of claim 2 wherein said metal foil is primed prior to being decorated and coated with said fluent plastic.

4. The method of claim 3 wherein said fluent plastic is cured by heating under infrared lamps (23).

5. The method of claim 4 wherein said substrate is held flat and horizontal on a vacuum mat (45 which also serves as a heat sink during the heat curing of said fluent plastic.

6. The method of claim 3 wherein said metal foil substrate is silk-screen printed and embossed to form a series of designs thereon.

7. The method of claim 1 wherein several sets of nozzles (49, 50) each having multiple orifices (61, 62) are passed in a single pass at a steady speed over the top surface of said substrate (12) while said substrate is held stationary.

8. The method of claim 1 wherein a single nozzle having multiple orifices is passed at a steady speed back and forth in several passes over the top surface of said substrate while said substrate is held stationary.

9. A method of producing decorative emblems comprising flow-coating a clear, viscous, fluent plastic on to the top surface of a decorated foil substrate (12) while the substrate is held flat and horizontal on a support surface (14), and allowing or causing the fluent plastic coating to cure while maintaining the substrate flat and horizontal to bond the said coating to the substrate, characterized by the steps of

(a) priming the top surface of an approximately 0.0762 to 0.508 mm thick aluminium foil sheet (12) having a top surface and a bottom surface,

(b) silk-screen printing and embossing said top face to form a series of individual decorative emblem shapes (82) thereon,

(c) allowing or causing the decorations to set prior to placing the bottom surface of said aluminium foil sheet on top of a vacuum mat (45) on a horizontal vacuum table (35),

(d) applying a vacuum draw to said bottom surface of said aluminium foil sheet through the vacuum mat (45) to hold said aluminium foil sheet flat and horizontal,

(e) flow-coating a clear viscous polyurethane in liquid form onto said top surface of said aluminium foil sheet by passing multiple orifices (61, 62) over said top surface at a steady speed as said aluminium foil sheet is held stationary and constantly ejecting liquid polyurethane from each of said orifices during the passage so that said liquid polyurethane flows to the edges of the aluminium foil sheet without flowing over said edges and forms a uniform coating of approximately 0.508 to 0.762 mm thick on said top surface,

(f) heating the coated aluminium foil sheet under infrared lamps (23) while said aluminium foil sheet is maintained flat and horizontal to cure said liquid polyurethane,

(g) cooling and removing the coated aluminium foil sheet from said vacuum mat, and

(h) stamping individual emblems from said aluminium foil sheet by application of a cutting die contiguous with each of said emblem shapes to the bottom surface of said aluminium foil sheet so that each emblem has a convex shape when viewed from said top surface.