NZ246793A - Retroreflective sheeting; laminated material incorporating retroreflective elements under a transparent film with phosphorescent pigment - Google Patents

Description

24 6 7 93 New Zealand No. 246793 International No. PCT/US93/00103 TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates: | £ - I- ^2 International fifing date: — ^ Classification: ^010^1 032.$~?} 12 Publication date: 2 8 AUG 1996 Journal No.: jlf.07 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of invention: Photolximinescent retroref lective sheeting Name, address and nationality of applicants) as in international application form STIMSONITE CORPORATION, of 7542 North Natchez Avenue, , Niles, Illinois 60648, United States of America US Corpcr&Mof\ • - | - (FOLLOWED BY PAGE 1 A) O 93/14422 246793 -iA DESCRIPTION PHOTOLPMINEBCENT RETROREFLECTIVE SHEETING TECHNICAL FIELD The invention relates generally to a photoluminescent retroreflective sheet material for use as a guide marker 10 and which has particular utility in buildings when a power outage occurs. Specifically, the present invention relates to a photolximinescent retroreflective sheeting combining both photoluminescent and retroreflective properties in a single product to be used to form a marker 15 system to help indicate exits, doorways, hazards, OSHA markings, pipe markings, high voltage areas, fire hoses and extinguishers and the like, when it is dark in the building, perhaps when caused by a power outage.

BACKGROUND OT THE INVENTION The term "building" as used throughout this application is intended to include any structure such as an aircraft, boat or other moveable and non-moveable conventional structures.

It is well known that within buildings at night or especially when the power has been lost, it is difficult to find ones way along the necessary corridors to the building exits, similarly, in some emergencies, the location of important fixtures such as fire alarms, 30 extinguishers, shut-off valves and the like are difficult to f ind.

O 93/14422 24 67 93 $8 CD O > UJ o •jj cc In the prior art, a photoluminescent material is utilized as a guide for such purposes. The luminous material is attached to doorways, hallways, and the like, so that in the event of a power outage, the photoluminescent material will glow in the dark and guide a person to an exit or along a prescribed path, of course, it is only useful to those individuals in the building that have adjusted their eyes to the darkness. Further, the luminescence produced is significantly lost within the first 20 minutes of an "outage." This makes it virtually useless to anyone entering the building after a short period of time.

The present invention overcomes the disadvantages of the prior art by providing a single sheeting material having both photoluminescent and retroreflective properties. The sheeting should exhibit the same photoluminescent properties as the current product being used, and it has significa'-*. retroreflective properties.

Thus it is an importan. object*of the present invention to provide a photoluminescent retroreflective sheet material that is designed to provide both photoluminescence and retroreflection of light.

It is also an object*of the present invention to provide a photolximinescent retroreflective sheeting in which a phosphorescent pigment is added to the retroreflective layer.

It is a further object*of the present invention to provide a photoluminescent retroreflective sheet in which the retroreflective layer has cube corner retroreflectors embossed on the backside thereof and covered by a predetermined pattern of hydrophobic silica. A backcoating contains the phosphorescent pigment and is in contact with the retroreflective layer in areas of the pattern not covered by the hydrophobic silica. i * These are objects of at least the preferred embodiments of the invention. 93/14422 24 67 93 LU O it o fc UJ £ Q_ i- JUL 1996 RECEIVLD N Z It is yet another object*of the present invention to provide a photoluminescent reflective sheet which has a transparent flexible film with retroreflective cube corners formed on the reverse surface thereof and a clear adhesive with phosphorescent pigment screen-printed in a pattern and cured on the cube corners.

It is believed that the present invention may be utilized with retroreflector sheeting produced in a variety of ways but will be particularly ureful with that retroreflective sheeting described and claimed in U.S. Patent No. 4,618,518, issued October 21, 1986, to Robert M. Pricone, et al. and assigned to applicants* assignee, the disclosure of which is incorporated by reference. Others forms and methods of producing retroreflective sheeting include those of "casting" cube corner elements, such as disclosed in Rowland U.S. Patents 3,810,804, issued May 14, 1974; 3,684,348, issued August 15, 1972; and 3,689,346, issued September 15, 1972.

Useful apparatus for embossing a film to provide cube corner retroreflective elements is disclosed in Pricone, et al. U.S. 4,601,861, issued July 22, 1986, commonly assigned. Other techniques for compression or sequential embossing are disclosed in Rowland U.S. 4,244,683, dated January 13, 1981.

Efforts have been made in the past to utilize fluorescent pigmented materials in conjunction with retroreflective sheet materials of the cube corner type. However, such use of fluorescent materials was intended to provide a combination of day/night visibility in highway signs. One example is that found in Rowland U.S. Patent 3,830,682, issued August 20, 1974. However, in such uses, unlike phosphors, the flourescent material would not continue to glow or provide light under "darkened" * This is an object of at least the preferred embodiments of the invention. fO 93/14422 24 67 93 PCT/US93/00103 v -4 — conditions but instead is illuminated by the light of certain wave lengths, so as to provide some "daylight" visibility to highway signs.

The present invention utilizes a phosphorescent 5 pigmentation in conjunction with retroreflective sheet material in a manner which does not materially impede the retroreflective capability of the sign when illuminated either under normal lighting conditions, such as in a building and under hallway lighting lights, nor does it 10 impede the "dark" or night light retroreflective capability when illuminated by a flashlight or other temporary light source.

SUMMARY oy THE IKVBHT1SM The present invention relates to a retroflective sheeting comprising a substantially transparent film having a plurality of retroreflective elements on the rear surface thereof, a patterned layer adjacent said rear surface of said film so as to define a pattern of cells, each cell including one or more retroreflective 20 elements out of contact with said patterned layer, and adhesive applied directly or indirectly thereto, the improvement consisting of a phosphorescent pigment contained in one or more of said layers so that said sheeting will emit phosphorescence to glow in the dark for a limited time after an illuminating source is M 3 removed, the phosphorescence emitted by said pigment being visible through the front surface of said substantially transparent film.

The present invention also relates to a method of forming a photoluminescent retroreflective sheeting comprising the steps of: providing cube corner retroreflectors in the rear surface of a transparent film to form a retroreflective layer for retroreflecting light incident on the front surface of said film; (followed by page 4a) 246 7 9 3 -4a- including a phosphorescent pigment to emit phosphorescence visible through the front surface of said film to cause the sheeting to glow in the dark; applying an adhesive directly or indirectly to the sheeting for attaching the sheeting to a surface; and removably attaching a release liner to the adhesive to prevent inadvertent contact of the adhesive with a surface.

Other embodiments are disclosed and claimed.

O 93/14422 246793 BRIEF DESCRIPTION OF THE DRAWINGS These and other objects of the present invention will be more fully understood when taken in conjunction with the following detailed description and the attached 5 drawings in which like numerals represent like elements and in which: FIG. l is a first embodiment that illustrates a cross sectional view of photoluminescent retroreflective sheeting of the present invention in which clear adhesive 10 with a phosphorescent pigment is screen printed in a pattern on the retroreflective cube corners formed on the rear surface of a transparent film; FIG. 2 is a cross-sectional view of a second embodiment of the present invention in which the 15 retroreflective layer of film has the cube corners embossed on the rear surface thereof and a hydrophobic silica pattern is applied on the embossed surfaces; a backcoating with phosphorescent pigment is applied over the hydrophobic silica and is in contact with the 20 otherwise exposed retroreflective cube corner elements; FIG. 3 is a cross-sectional view of a third embodiment of the present invention in which the retroreflective layer has the cube corner reflectors on one side thereof and which layer also contains the phosphorescent pigment 25 for enabling the sheet to be seen when not illuminated by an external source. An adhesive layer is applied over the hydrophobic silica layer and exposed cuber corner elements, and a release liner is added to prevent accidental contact of the adhesive with a substrate 30 surface; FIG. 4 is a cross-sectional view of yet another embodiment of the present invention, in which the retroreflective layer contains the phosphorescent pigment; 24 8 7 93 VO 93/14422 PCT/US93/00103 • the hydrophobic silica is screened in a pattern over the embossed cube corner retroreflectors on the retroreflective layer; a white backcoating is applied to the silica layer and to the exposed cube corner elements, 5 an adhesive layer is added and a release liner is applied to prevent the adhesive from accidentally touching a surface; FIG. 5 is a flow diagram of a process for making one embodiment of the present invention; FIG. 6 is a flow chart illustrating the process for making the invention illustrated in FIG. 2 of the present invention; FIG. 7 is a flow chart illustrating the process for making the embodiment of FIG. 3 of the drawings; 15 FIG. 8 is a schematic drawing of the flow chart for making the photoluminescent retroreflective sheeting of the FIG. 4 embodiment; and FIG. 9 is a cross-sectional view of another embodiment of the invention in which the phosphorescent pigment is 20 utilized with "beaded sheeting" containing microspheres to provide retroreflectivity.

DETAILED DESCRIPTION OP THE DRAWINGS A preferred embodiment of the present photoluminescent retroreflective sheeting is illustrated in cross-section in FIG. 1. The sheet comprises a first layer of transparent retroreflective film 12 that is formed generally in accordance with the method and apparatus disclosed in the aforesaid Pricone U.S. patent No. 4,486,363. However, as noted, other methods of forming a film with cube corner retroreflector elements (or spherical retroreflectors) may be used.

/O 93/14422 PCT/US93/00103 ' 246793 In the preferred form, the film 12 is approximately 0.006-0.008 inches thick and has a plurality of retroreflective corner cube elements 13 embossed on the rear side thereof. it also has a layer of clear adhesive 14 containing a phosphorescent pigment screened in a preselected pattern over certain of the cube corner elements 13 so as to leave spaces or cells 22. One such adhesive 14 may be that known as Flexcrill GP-2, sold by Air Products, Inc., and 10 applied by screen printing. This is a water based acryclic.

The adhesive 14 contains a phosphorescent pigment which may be of a type known as P-1000, sold by Hanovia, a division of Conrad, Inc..of Newark, N.J. and which is 15 commercially available. Other phosphorescent pigments may be used. The pigment may be batch mixed with the adhesive so as to constitute about 30% by weight thereof.

Other adhesives that may prove satisfactory would be drawn from unpigmented acrylics; urethanes; UV curable 20 100% solids; the criteria being that the adhesive bond between the resin layer and back layer be flexible and be readily applied.

The transparent retroreflective film 12 with the clear adhesive 14 and containing the phosphorescent pigment 25 therein is then cured by heating or, if appropriate, and if UV curable, then curing can be accelerated.

After curing, an opaque layer of material 16, (such as polyester, PVC, or Mylar), is then applied over the transparent clear adhesive 14 with the phosphorescent 30 pigment, to complete the "air" cells 22. The air cells permit retroreflectivity to be achieved, as is known in the art. Preferably, this layer 16 will be of a white color to enhance the brightness of the phosphorescent effect, but other colors or metallized films may be used.

O 93/14422 PCT/US93/00103 v. 246793 An adhesive fourth layer 18 then may be applied to the white layer 16, enabling the sheeting material to be attached to a surface. A release liner 20 is applied to the adhesive layer 18 to prevent inadvertent contact of 5 the adhesive with a surface until the user is ready to install the sheeting.

In the embodiment of FIG. 1, the retroreflective cells 22 allow the transparent film 12 to be retroreflective and reflect light impinging upon the front surface. The clear 10 adhesive 14 with the phosphorescent pigment allows the strip to glow in the dark so that it can be followed by an individual. Thus, such sheeting can be used to form guidance systems that mark exits, doorways, hazards and the like in the case of a power outage. When the 15 photoluminescent property of the sheets fail then the retroreflective cube corner elements will retroreflect incident light, such as from a flashlight or the like carried by service individuals such as police, fire or utility department officials.

In FIG. 2, the sheeting 24 could be formed of a retroreflective layer of transparent flexible film 26 with cube corner retroreflective elements 27 formed on the reverse side thereof by embossing, to reflect incident light thereon. A hydrophobic silica layer 28 is screen 25 printed in a pattern over the cube corner retroreflective cells 27. A clear water-based backcoating 30 is then placed over the hydrophobic silica 28. The backcoating contains the phosphorescent pigment. A white pigment adhesive 32 is laminated to the backcoating 30 for 30 attaching the sheet to a surface. White pigment is used to enhance reflectivity as well as brightness of the phosphorescent material. A release liner 34 is laminated O 93/14422 24 67 93 to the adhesive to prevent the adhesive 32 from inadvertently contacting a surface until the user is ready.

In the embodiment illustrated in FIG. 3, the 5 retroreflective layer 38 also includes the phosphorescent pigment therein. The hydrophobic silica 42 is then screened on the cube corners 40 in a predetermined pattern and a white pigmented adhesive 44 is coated over the hydrophobic silica pattern. Again, a release liner 46 is 10 laminated to the adhesive 44 to prevent the sheet from inadvertently sticking to a surface until the user is ready for it.

Other advantageous uses of the present invention with respect to retroreflective sheeting of other kinds, such 15 as metallizing over some or all of the reflector elements, also will be recognized. Thus, for example, retroreflective sheeting material is disclosed and Martin U.S. Patent 4,801,193 may be provided with the phosphorescent pigmentation advantageously employed in the 20 present invention.

In the embodiment illustrated in FIG. 4, the sheet 48 is again formed of a transparent flexible film 50 that has retroreflective cube corner elements 52 formed on the reverse side thereof and which contains the phosphorescent 25 pigment described earlier. Again, a hydrophobic silica 54 is screened on the cube corners of the translucent reflective flexible film 50 in a predetermined pattern. A white backcoating 56 as described earlier is coated over the hydrophobic silica 54. An adhesive layer 58 is 30 laminated to the white backcoating 56 and a release liner 60 is laminated to the adhesive 58 to prevent the adhesive from inadvertently contacting a surface before the user desires. 246793 The method of application and composition of the > hydrophobic silica, 'backcoating and adhesive as discussed herein may be as disclosed in the aforesaid Pricone et al. 'U.S. Patent No. 4,618,518.

A process for forming the photoluminescent retroreflective sheeting shown in FIG. 1 is illustrated in FIG. 5. The transparent flexible film may be extruded and have retroreflective cube corner elements embossed or cast on the reverse side thereof at step 64. At step 68, a clear adhesive containing a phosphorescent pigment is screen printed in a predetermined pattern on the cube corner elements on the reverse or rear side of the flexible film. At step 70, the adhesive is cured and at step 72 an opaque film, preferably white, is adhered to the adhesive to form air cells. At step 74, an adhesive layer is added to the film and at step 76 a release layer is laminated to the adhesive layer to prevent the adhesive from adhering to a surface prior to the time it is needed.

Fig. 6 illustrates the process steps for forming the invention of FIG. 2. Again, in step 1, the transparent flexible film is extruded. At step 78 retroreflective cube corners are formed on the reverse side by casting or embossing. At step 82, hydrophobic silica is screen printed in a pattern over the cube corner elements. At step 84, the silica is coated with a clear water-based backcoating containing the phosphorescent pigment. A white (or other color) pigmented adhesive is applied to the silica coating at step 86 and a release layer is laminated to the pigmented adhesive at step 88 to prevent the adhesive from inadvertently sticking to a surface.

FIG. 7 is a flow chart of the process for forming the photoluminescent retroreflective sheeting illustrated in FIG, 3. As can be seen in FIG. 7, the flexible film is extruded and contains the phosphorescent pigment which glows in the dark. The retroreflective cube corner elements are then embossed on the reverse side of the extruded flexible film at step 92. Hydrophobic silica is then screen printed on the cube corners in a predetermined pattern at step 94. A water-based backcoating adhesive is applied to the hydrophobic silica at step 96 and the adhesive coating layer may be cured at step 97. Finally, a release liner is laminated to the adhesive at step 98 to prevent the product from sticking to a surface inadvertently.

The flow chart of FIG. 8 discloses the method of making the sheeting sample illustrated in FIG. 4. Again, at step 100/ the flexible film containing the phosphorescent pigment is extruded. In step 102 the reverse side of the sheet is embossed with the cube corner elements. In step 104, the hydrophobic silica is coated with a pigmented water-based backcoating, preferably white. At step 108 the layer of adhesive is applied to the backcoating and in step 110 a release liner is laminated to the adhesive. Again, such liner is used to prevent the adhesive from inadvertently sticking to a surface before it is intended to be used.

Since the present film is primarily to be used indoors, additional qverlays or other ultraviolet inhibitors which help prevent deterioration of outdoor retroreflective sheeting may not be necessary, further reducing the processing cost.

FIG. 9 discloses a sample microsphere beaded type sheet material 130 employing the present invention. The beaded sheeting 130 may be of the type produced by 3M MO 93/14422 PCT/US93/00103 v 246793 Corporation and sold under the trademark Scotchlite®. It is believed such material is made in accordance with various 3M patents such as Nos. 2,407,680 and 4,511,210. In this embodiment the sheeting comprises a layer of 5 monosphere beads 135 and a transparent layer of resin below which may be a specially reflecting surface 136. The phosphorescent pigment 134 may be employed in an overlay over the beads, or in the binder layer 137 in which the beads are embedded. In the case of so-called 10 high intensity beaded sheets, the phosphorescent pigment may be incorporated into the cell walls. A layer of adhesive 138 and a release liner 139 also may be used.

It will be appreciated from the foregoing that the present invention provides significant advantages for 15 safety purposes in that dual functions can be obtained while utilizing sheeting having a high degree of retroreflectivity and photoluminescence while minimizing the amount of material required for each such purpose.

While the invention has been described in connection 20 with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as 25 defined by the appended claims.

Claims (1)

1. It •» / / £'i- (j / WO 93/14422 13 PCT/US93/00103 CfrAIMg 1. A phosphorescent and retroreflective sheeting for use in a multi-functional marker for a visual guidance system, said sheeting 5 material comprising: (a) a first layer of a substantially transparent polymer resin having a front surface and a rear surface, said rear surface having retroreflective elements to 10 retroreflect light incident on said front surface; (b) a patterned layer overlaying said rear surface of said first layer and adhered thereto to be in contact with some 15 of said retroreflective elements and essentially out of contact with others of said retroreflective elements, so as to define a pattern of cells, each cell including a number of retroreflective 20 elements out of contact with said patterned layer; (c) an adhesive layer applied to said patterned layer to adhere said sheeting layer to an associated surface; 25 and (d) a phosphorescent pigment contained within one or more of said layers, the phosphorescence emitted by said pigment being visible through said 30 front surface of said first layer, whereby said sheeting can function as a marker for a visual guidance system by emitting phosphorescent luminescence after a source of illumination is removed, and i 35 by retroreflecting visible light incident on the front surface of said first layer. 24 H19 93/14422 14 PCT/US93/00103 2. The sheeting of claim 1, wherein hydrophobic silica is disposed within the cells of said patterned layer. 3s. The sheeting of claim 2, in which said patterned layer comprises a clear adhesive. 4. The sheeting of claim 3, in which said phosphorescent pigment is contained in said patterned layer. 5. The sheeting of claim 1, and further including an opaque layer to enhance the luminescence of said phosphorescent pigment. 6. The sheeting of claim 5, wherein said opaque layer is white. 7. The sheeting of claim l, in which said phosphorescent pigment is contained in said first layer. 8. The sheeting of claim 7, in which said film is flexible and said retroreflecting *;elements are cube corner elements formed by embossing.;9.' The sheeting of claim 1, in which said reitroreflecting elements constitute cube corner retroreflective elements formed by casting.;10. The sheeting of claim 1, in which at least a portion of said retroreflecting elements are metalized and said adhesive layer;d'i£}7 9 3;%;ftiV-j;WO 93/14422 15 PCT/US93/00103;is applied to portions of said metalized surfaces.;11. The sheeting of claim 1, wherein said 5 retroreflective elements comprise a matrix of microsphere beads.;12. In a cube corner retroreflective sheeting comprising a substantially transparent;10 and flexible film having a plurality of cube corner retroreflective elements on the rear surface thereof, a patterned layer adjacent said rear surface of said film so as to define a pattern of cells, each cell including one or 15 more retroreflective elements out of contact with said patterned layer, and having one or more additional layers of backcoating or metallizing and adhesive applied thereto, the improvement consisting of a phosphorescent 20 pigment contained in one or more of said layers so that said sheeting will emit phosphorescence to glow in the dark for a limited time after an r;illuminating source is removed, the phosphorescence emitted by said pigment being 25 visible through the front surface of said substantially transparent film.;13. A photoluminescent retroreflective sheeting comprising:;30 a first layer of retroreflective film having a front surface and a pattern of cube corner retroreflector elements formed on the reverse surface to retroreflect light incident on said front surface; 35 i a second layer of clear adhesive screen printed in a pattern of cells and cured on said cube corner elements, each;24679;WO 93/14422 16 PCT/US93/00103;cell including one or more cube corner elements out of contact with said second layer;;a third layer of film adhered to the 5 printed pattern and otherwise spaced from said uncoated cube corner elements to se-il said cells;;an adhesive layer formed on said film for attaching the sheet to a surface; 10 a release liner removably secured to the adhesive layer to prevent inadvertent contact of the adhesive layer with a surface; and a phosphorescent pigment contained in 15 at least one of said first, second or third layers to cause the sheeting to glow in the dark by emitting phosphorescence visible through the front surface of said first layer, and coloration pigmentation 20 contained within one or more layers disposed behind said layer containing said phosphorescent pigment.;14. The photoluminescent retroreflective 25 sheeting as in claim 13, wherein said phosphorescent pigment is in said second layer of clear adhesive.;15. The photoluminescent retroreflective 30 sheeting as in claim 13, wherein said phosphorescent pigment Is in said first layer of retroreflective film.;i;35 16. Photoluminescent retroreflective sheeting comprising:;#;p r-> •':? ,:a -"7;^4 o / 9 o;WO 93/14422 17 PCT/US93/00103;a transparent film having cube corner retroreflectors embossed on the reverse surface thereof for retroreflecting light incident on the front surface of said 5 film;;a layer of hydrophobic silica screen printed in a pattern of cells on the cube corner elements, each cell including one or more cube corner elements out of 10 contact with said hydrophobic silica;;a clear backcoating containing phosphorescent pigment formed over the hydrophobic silica layer and otherwise spaced from the exposed cube corner 15 elements to seal said cells, said pigment emitting phosphorescence visible through the front surface of said transparent film to cause the sheeting to glow in the dark; an adhesive secured to the backcoating 20 for attaching the sheet to a surface.;17. Photoluminescent retroreflective sheeting comprising: 25 a layer of transparent extruded film embossed on the rear surface with retroreflective cube corner elements that retroreflect light incident on the front surface of said film; 30 a phosphorescent pigment contained in the extruded film so said pigment will emit phosphorescence visible through said front surface of said film and will glow in the dark;;4;35 hydrophobic silica screen-printed in a predetermined pattern of cells on the extruded cube corner elements;;J N.Z. PATENT OFRCZ 1- JUL 1996;RECEIVLD;t;^ / /*s "T ,'A f L\ /• y WO 93/14422 18 PCT/US93/00103 a white pigmented adhesive formed over the silica pattern and otherwise spaced from the exposed cube corner elements to seal said cells and for 5 attaching the sheet to a surface; and a release liner attached to said adhesive to prevent inadvertent contact of said adhesive with a surface. 10 18. Photoluminescent retroreflective sheeting comprising: a first layer of transparent thermoplastic film embossed on the rear surface thereof with retroreflective cube 15 corner elements for retroreflecting light incident on the front surface of said film; a phosphorescent pigment contained in the film so said pigment will emit 20 phosphorescence visible through said front surface of said film such that said first layer glows in the dark; hydrophobic silica screen-printed on the rear surface of said first layer in a 25 predetermined pattern of cells; a white pigmented water-based backcoating formed over the hydrophobic silica pattern to seal said cells; a layer of adhesive attached to the 30 backcoating for attaching the sheet to a surface; and a release liner attached to the layer of adhesive to prevent accidental contact of the adhesive with a surface. 1 35 N.Z. PATENT 1- JUL 1996 RECE1VLD % WO 93/14422 19 PCT/US93/00103 35 19. A method of forming a photoluminescent retroreflective sheeting comprising the steps of: embossing cube corner retroreflector v elements on the rear surface of a thin flexible film to form a retroreflective layer that will retroreflect light incident on the front surface thereof; screen printing a second layer of clear adhesive in a predetermined pattern of cells on said rear surface of said film, each cell including one or more retroreflective elements out of contact with said second layer; curing said second layer; laminating a third layer of film on the printed pattern and otherwise spaced from said uncoated cube corners to seal said cells;. applying an adhesive fourth layer to the third film layer for attaching the sheeting to a surface; removably securing a release liner to the adhesive layer to prevent inadvertent contact of the adhesive layer with a surface; and including a phosphorescent pigment in at least one of said first, second or third layers to emit phosphorescence visible through the front surface of said embossed thin flexible film to cause the sheeting to glow in the dark. 20,. The method as in claim 19, wherein the phosphorescent pigment is placed in the second layer of clear adhesive. ft 9467 9 3 WO 93/14422 20 PCT/US93/00103 21. The method as in claim 19, wherein the phosphorescent pigment is placed in the : Ji..- embossed retroreflective film. 5 22. The method as in claim 19, wherein the phosphorescent pigment is placed in the third film layer laminated on the printed pattern. 10 23. A method of forming a photoluminescent retroreflective sheeting comprising the steps of: embossing cube corner retroreflectors in the rear surface of a transparent 15 flexible film to form a retroreflective layer for retroreflecting light incident on the front surface of said film; screen-printing a layer of hydrophobic silica in a predetermined 20 pattern of cells on the cube corners; forming a clear water-based backcoating containing phosphorescent pigment over the hydrophobic silica layer to seal said cells, said phosphorescent pigment 25 being able to emit phosphorescence visible through the front surface of said embossed film to cause the sheeting to glow in the dark; applying a pigmented adhesive to the 30 backcoating for attaching the sheeting to a surface; and removably attaching a release liner to the pigmented adhesive to prevent inadvertent contact of the adhesive with a i 35 surface. N.Z. PATENT OFFICE 1- JUL 1996 RECEIVLD 24 6 7 § WO 93/14422 20 PCT/US93/00103 21. The method as in claim 19, wherein the phosphorescent pigment is placed in the embossed retroreflective film. 5 22. The method as in claim 19, wherein the phosphorescent pigment is placed in the third film layer laminated on the printed pattern. 10 23. A method of forming a photoluminescent retroreflective sheeting comprising the steps of: embossing cube corner retroreflectors in the rear surface of a transparent 15 flexible film to form a retroreflective layer for retroreflecting light incident on the front surface of said film; & screen-printing a layer of hydrophobic silica in a predetermined 20 pattern of cells on the cube corners; forming a clear water-based back coating containing phosphorescent pigment over the hydrophobic silica layer to seal said cells, said phosphorescent pigment 25 being able to emit phosphorescence visible through the front surface of said embossed film to cause the sheeting to glow in the dark; applying a pigmented adhesive to the 30 bagk coating for attaching the sheeting to a surface; and removably attaching a release liner to the pigmented adhesive to prevent inadvertent contact of the adhesive with a i 35 surface. 24 6 7 93 93/14422 21 PCT/US93/00103 24. A method of forming a photoluminescent retroreflective sheeting comprising the steps of: embossing a layer of extruded transparent film including a phosphorescent pigment with cube corner retroreflector elements on the rear surface thereof for retroreflecting light incident on the front surface thereof, said pigment emitting phosphorescence visible through-the front surface of said film;- ' • screen-printing a hydrophobic silica on the embossed cube corner retroreflectors to define a predetermined pattern of cells of unprinted retroreflector elements; forming a white pigmented water-based backcoating over the hydrophobic silica pattern and out of contact with said unprinted retroreflector elements to seal said cells; applying a layer of adhesive to the backcoating for attaching the sheeting to a surface; and attaching a removable release liner to the layer of adhesive to prevent accidental contact of the adhesive with a surface. 1 N.Z. PATENT OFFICE 1- JUL 1996 RECEIVLD 246 7S 3 22 25. A retroreflective sheeting comprising a substantially transparent film having a plurality of retroreflective elements on the rear surface thereof, a patterned layer adjacent said rear surface of said film so as to define a pattern of cells, each cell including one or more retroreflective elements out of contact with said patterned layer, and adhesive applied directly or indirectly thereto, the improvement consisting of a phosphorescent pigment contained in one or more of said layers so that said sheeting will emit phosphorescence to glow in the dark for a limited time after an illuminating source is removed, the phosphorescence emitted by said pigment being visible through the front surface of said substantially transparent film. 26. A retroreflective sheeting according to claim 25 wherein the retroreflective elements comprise cube corners. 27. A retroreflective sheeting according to claim 25 or claim 26 wherein the transparent film is flexible. 28. A retroreflective sheeting according to any one of claims 25-27 including one or more additional layers of backcoating or metallizing applied thereto. N.Z. PATENT OFFICE 1- JUL 1996 RECEIVLD 246793 23 29. A method of forming a photoluminescent retroreflective sheeting comprising the steps of: providing cube corner retroreflectors in the rear surface of a transparent film to form a retroreflective layer for retroreflecting light incident on the front surface of said film; including a phosphorescent pigment to emit phosphorescence visible through the front surface of said film to cause the sheeting to glow in the dark; applying an adhesive directly or indirectly to the sheeting for attaching the sheeting to a surface; and removably attaching a release liner to the adhesive to prevent inadvertent contact of the adhesive with a surface. 30. A method according to claim 29 wherein the transparent film is flexible. 31. A method according to claim 29 or 30 wherein a layer of hydrophobic silica is screen-printed in a predetermined pattern of cells on the cube corners. patent office 1- JUL 1996 heceivld 2 4 6 7 d 24 32. A method according to any one of claims 29-31 wherein the phosphorescent pigment is applied by forming a clear water-based backcoating over the hydrophobic silica layer. 33. A method according to claim 32 wherein the adhesive is applied to the backcoating. 34. A method according to any one of claims 29-33 wherein the adhesive is pigmented. 35. A phosphorescent and retroreflective sheeting for use in a multi-functional marker for a visual guidance system, substantially as herein described with reference to any embodiment shown in the drawings. 36. A cube corner retroreflective sheeting substantially as herein described with reference to any embodiment shown in the drawings. 37. A photoluminescent retroreflective sheeting substantially as herein described with reference to any embodiment shown in the drawings. N.Z. PATENT OFFICE 1 - JUL 1996 t_ i RECEIVLD 246 7 9 3 25 38. A method according to any one of claims 19, 23, 24 and 29 and substantially as herein described with reference to any embodiment disclosed. 39. A photoluminescent retroreflective sheeting when formed by the method of any one of claims 19 to 24, 29 and 38. By the authorised agents A J PARK & SON /0 ^ . fa j N.Z. PATENT OFFICE J 1' JUL 1996 L ReceTvlo