Title:
Rigid non-transparent photoluminescent floor material
Kind Code:
A1


Abstract:
A rigid, non-transparent photoluminescent tile having photoluminescent material exposed on a top surface of the tile, wherein the photoluminescent material, including photoluminescent particles and chips, illuminates when the ambient light is removed.



Inventors:
Nolt, Robert (Lancaster, PA, US)
Application Number:
10/993399
Publication Date:
07/21/2005
Filing Date:
11/19/2004
Assignee:
ND Holdings, Inc. (Lancaster, PA, US)
Primary Class:
Other Classes:
428/411.1, 524/425, 428/323
International Classes:
A62B3/00; B32B27/20; B44C5/04; E04F15/02; E04F15/08; G09F13/20; (IPC1-7): B32B27/20; C08K3/26
View Patent Images:



Primary Examiner:
ROBINSON, ELIZABETH A
Attorney, Agent or Firm:
SEED INTELLECTUAL PROPERTY LAW GROUP LLP (701 FIFTH AVE SUITE 5400, SEATTLE, WA, 98104, US)
Claims:
1. A rigid photoluminescent tile comprising: a tile base having a top surface; a thermoplastic binder system within said tile base, the thermoplastic binder system being 5-50 wt % of the total weight of the tile; a non-transparent inorganic filler within said tile base; and a photoluminescent material within the tile base and being exposed on said top surface of said tile base, wherein the combined weight of the inorganic filler and the photoluminescent material is 50-95 wt % of the total weight of the tile.

2. The photoluminescent tile of claim 1 wherein the combined weight of the inorganic filler and the photoluminescent material forms 60-90 wt % of the total weight of the tile.

3. The photoluminescent tile of claim 1 wherein the combined weight of the inorganic filler and the photoluminescent material forms 70-85 wt % of the total weight of the tile.

4. The photoluminescent tile of claim 1 wherein the inorganic filler is limestone.

5. The photoluminescent tile of claim 1 wherein the photoluminescent material is distributed evenly throughout the entire tile base.

6. The photoluminescent tile of claim 5 wherein the photoluminescent material comprises a plurality of fine photoluminescent particles.

7. The photoluminescent tile of claim 6 wherein the photoluminescent particles comprise 10-90 wt % of the total weight of the tile.

8. The photoluminescent tile of claim 7 wherein the photoluminescent particles comprise about 20 wt % of the total weight of the tile.

9. The photoluminescent tile of claim 5 wherein the photoluminescent material comprises a plurality of photoluminescent chips, each of said photoluminescent chips includes a thermoplastic binder system and photoluminescent particles, wherein the thermoplastic binder system is 5-50 wt % of the weight of each individual chip.

10. The photoluminescent tile of claim 9 wherein the photoluminescent chips further include a non-transparent inorganic filler, and the combined weight of the inorganic filler and the photoluminescent particles is 50-95 wt % of the weight of each individual chip.

11. The photoluminescent tile of claim 9 wherein the photoluminescent chips further include a plurality of non-photoluminescent color pigments.

12. The photoluminescent tile of claim 9 wherein the photoluminescent chips are about 2-20 mils in dimension.

13. The photoluminescent tile of claim 9 wherein the photoluminescent chips are about 2-10 mils in dimension.

14. The photoluminescent tile of claim 9 wherein the photoluminescent chips comprise about ¼ to ¾ of the total weight of the tile.

15. The photoluminescent tile of claim 14 wherein the photoluminescent chips comprise about ⅓ of the total weight of the tile.

16. The photoluminescent tile of claim 9 wherein the photoluminescent particles are 10-90 wt % of the weight of each individual photoluminescent chip.

17. The photoluminescent tile of claim 16 wherein the photoluminescent particles is about 20 wt % of the weight of each individual photoluminescent chip.

18. The photoluminescent tile of claim 1 the photoluminescent material is embedded in a portion of the tile base on and near the top surface to form a wear layer.

19. The photoluminescent tile of claim 18 wherein said photoluminescent material covering at least 10% of the surface area on the top surface.

20. The photoluminescent tile of claim 18 wherein the wear layer is 10-20% of the overall thickness of the tile.

21. The photoluminescent tile of claim 20 wherein the wear layer is 2-20 mils in thickness.

22. The photoluminescent tile of claim 20 wherein the wear layer is 2-10 mils in thickness.

23. The photoluminescent tile of claim 18 wherein the photoluminescent material comprises a plurality fine photoluminescent particles.

24. The photoluminescent tile of claim 18 wherein the photoluminescent material comprises said photoluminescent chips include a thermoplastic binder system and photoluminescent particles, wherein the thermoplastic binder system comprises 5-50 wt % of the weight of each chip.

25. The photoluminescent tile of claim 24 wherein the photoluminescent chips further comprises a non-transparent inorganic filler and the combined weight of the inorganic filler and the photoluminescent particles is 50-95 wt % of the weight of each chip.

26. The photoluminescent tile of claim 24 wherein the photoluminescent chips are about 2-20 mils in dimension.

27. The photoluminescent tile of claim 24 wherein the photoluminescent chips are about 2-10 mils in dimension.

28. The photoluminescent tile of claim 24 wherein the photoluminescent particles comprise about 10-90 wt % of the weight of each individual photoluminescent chip.

29. The photoluminescent tile of claim 28 wherein the photoluminescent particles comprise about 20 wt % of the weight of each individual photoluminescent chip.

30. The photoluminescent tile of claim 18 wherein the wear layer is a layer separately processed and laminated on top of the non-photoluminescent tile base.

31. The photoluminescent tile of claim 1 further comprising a plurality of non-photoluminescent color pigments.

32. A photoluminescent tile comprising a non-photoluminescent substrate; a wear layer having a top surface and a bottom surface, said bottom surface being affixed to the substrate, a thermoplastic binder system within said wear layer, said thermoplastic binder system being about 5-50 wt % of the total weight of the wear layer; a non-transparent inorganic filler within said wear layer, a photoluminescent material within said wear layer and being exposed on the top surface of said wear layer, wherein the combined weight of the inorganic filler and the photoluminescent material is about 50-95 wt % of the total weight of the wear layer.

33. The photoluminescent tile of claim 32 wherein the substrate is a non-photoluminescent tile base comprising, of the total weight of the tile base, 5-50 wt % thermoplastic binder system and 50-95 wt % non-transparent inorganic filler.

34. The photoluminescent tile of claim 32 wherein the combined weight of the inorganic filler and the photoluminescent material is 60-90 wt % of the total weight of the wear layer.

35. The photoluminescent tile of claim 32 wherein the combined weight of the inorganic filler and the photoluminescent material is 70-85 wt % of the total weight of the wear layer.

36. The photoluminescent tile of claim 32 wherein the photoluminescent material comprises a plurality of fine photoluminescent particles.

37. The photoluminescent tile of claim 36 wherein the photoluminescent particles comprise 10-90 wt % of the total weight of the wear layer.

38. The photoluminescent tile of claim 37 wherein the photoluminescent particles comprise about 20 wt % of the total weight of the wear layer

39. The photoluminescent tile of claim 32 wherein the photoluminescent material comprises a plurality of photoluminescent chips, said photoluminescent chips include a thermoplastic binder system and photoluminescent particles, wherein the thermoplastic binder system comprises about 5-50 wt % of the weight of each individual chip.

40. The photoluminescent tile of claim 39 wherein the photoluminescent chips further comprise a non-transparent inorganic filler, wherein the combined weight of the inorganic filler and the photoluminescent particles forms 50-95 wt % of the weight of each chip.

41. The photoluminescent tile of claim 39 wherein the photoluminescent chips are about 2-20 mils in dimension.

42. The photoluminescent tile of claim 39 wherein the photoluminescent chips are about 2-10 mils in dimension.

43. The photoluminescent tile of claim 39 wherein the photoluminescent chips comprise about ¼ to ¾ of the total weight of the wear layer.

44. The photoluminescent tile of claim 43 wherein the photoluminescent chips comprise about ⅓ of the total weight of the wear layer.

45. The photoluminescent tile of claim 39 wherein the photoluminescent particles comprise about 10-90 wt % of the weight of each individual photoluminescent chip.

46. The photoluminescent tile of claim 45 wherein the photoluminescent particles comprise about 20 wt % of the weight of each individual photoluminescent chip.

47. The photoluminescent tile of claim 38 further comprising a plurality of non-photoluminescent color pigments.

48. A floor comprising: a plurality of rigid photoluminescent tiles, said photoluminescent tiles including a tile base having a top surface, a thermoplastic binder system within said tile base, the thermoplastic binder system being 5-50 wt % of the total weight of the tile; a non-transparent inorganic filler within said tile base; and a photoluminescent material within the tile base and being exposed on said top surface of said tile base, wherein the combined weight of the inorganic filler and the photoluminescent material is 50-95 wt % of the total weight of the tile; and a plurality of rigid non-photoluminescent tile.

49. The floor of claim 48 wherein the photoluminescent tiles form a pattern.

Description:

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. application Ser. No. 10/271,243 entitled “Photoluminescent Floor Tile”, filed on Oct. 15, 2002, now allowed, which claims priority to U.S. patent application Ser. No. 10/147,740 entitled “Photoluminescent Floor Tile”, filed on May 16, 2002, now allowed, which applications are incorporated herein by references in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is related to rigid non-transparent photoluminescent flooring material. In particular, the invention relates to floor tiles having light-emitting wear layers that illuminate when the ambient light is removed.

2. Description of the Related Art

Buildings are provided with emergency signs marking exits and fire escape routes. These signs direct persons out of the building in the event of an emergency. Because the electric service is likely to be lost during an emergency, the emergency signs tend to be powered by an emergency backup system which typically include batteries and generators. Additionally, emergency lights are required in certain buildings to provide illumination for the evacuees. These emergency lights are also powered by backup batteries and generators.

The emergency backup system that powers lights and emergency signs has disadvantages. The backup lighting system must provide coverage for all escape routes. Extensive coverage can lead to costly installation. Moreover, maintenance of the emergency backup system is critical in ensuring reliable performance during an emergency. Accordingly, although the emergency events are infrequent, routine maintenance of the backup system is necessary.

Because of these disadvantages, emergency lighting systems that do not rely on power have been developed to supplement powered backup system. One type of the non-powered system employs photoluminescent material to provide the light. Photoluminescent material absorbs lights from ambient sources. The absorbed photon energy is readily released, often at a particular wavelength. The photoluminescent light emitted can be particularly bright in the dark, which makes the material a good candidate for providing a non-powered backup system to mark the emergency exits and escape routes. Some of the photoluminescent materials are so efficient in storing and releasing the photon energy, they are capable of emitting light for hours after the ambient light has been removed.

Flexible sheets or mats are among the most common material into which photoluminescent material can be distributed and fused. The photoluminescent sheets and mats are typically affixed to a surface, such as a floor or walls, which will light up and provide illumination in the dark. The installation is often labor intensive due to the additional step of affixing the light-emitting material to an existing floor or walls. It further requires special treatment of the surfaces to ensure a failsafe affixation. Often, these sheets and mats do not provide a pleasing appearance under normal light.

Another type of building material that illuminates in the dark is disclosed in U.S. Pat. No. 6,309,562 by Sakai. Sakai discloses an artificial stone incorporating a small amount of photoluminescent material into largely transparent inorganic aggregates, such as silica. The photoluminescent material is expected to illuminate through the entire thickness of the artificial stone due to the transparency of the stone.

SUMMARY OF THE INVENTION

The present invention provides a rigid, photoluminescent tile that illuminates when the ambient light is removed. In particular, the photoluminescent tile comprises a tile base having a top surface, a thermoplastic binder system within said tile base, the thermoplastic binder system being 5-50 wt % of the total weight of the tile, a non-transparent inorganic filler within said tile base; and a photoluminescent material within the tile base and being exposed on said top surface of said tile base, wherein the combined weight of the inorganic filler and the photoluminescent material is 50-95 wt % of the total weight of the tile. The photoluminescent material can be photoluminescent particles or chips.

In a further embodiment, the present invention provides a photoluminescent tile having a non-photoluminescent substrate bonded with a wear layer. The wear layer has a top surface and a bottom surface and includes a thermoplastic binder system within said wear layer, said thermoplastic binder system being about 5-50 wt % of the total weight of the wear layer; a non-transparent inorganic filler within said wear layer, a photoluminescent material within said wear layer and being exposed on the top surface of said wear layer, wherein the combined weight of the inorganic filler and the photoluminescent material is about 50-95 wt % of the total weight of the wear layer. The photoluminescent material can be photoluminescent particles or chips.

The present invention further provides a floor comprise a plurality of the photoluminescent tile according to the various embodiments of the invention and a plurality of non-photoluminescent tiles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a floor tile in accordance with one embodiment of the present invention, in which photoluminescent particles are evenly distributed throughout the entire body of the tile.

FIG. 2 is a sectional view of the floor tile shown in FIG. 1.

FIG. 3 is a enlarged view of a portion of the tile shown in FIGS. 1-2.

FIG. 4a is a top view of a floor tile in accordance with another embodiment of the present invention, in which photoluminescent chips are distributed in a non-photoluminescent tile base.

FIG. 4b is a top view of a floor tile in accordance with yet another embodiment of the present invention, in which photoluminescent chips are distributed in a non-photoluminescent tile base.

FIG. 5 is a top view of a floor arrangement comprising a plurality of photoluminescent tiles and non-photoluminescent tiles.

FIG. 6 is a top view of a floor arrangement comprising a plurality of photoluminescent tiles and non-photoluminescent tiles.

FIG. 7 is a sectional view of a floor tile in accordance with yet another embodiment of the present invention, in which a photoluminescent wear layer having photoluminescent particles overlies a non-photoluminescent tile base.

FIG. 8 is a sectional view of a floor tile in accordance with yet another embodiment of the present invention, in which a photoluminescent wear layer having photoluminescent chips overlies a non-photoluminescent tile base.

FIG. 9 is a sectional view of a floor tile in accordance with yet another embodiment of the present invention, in which photoluminescent particles are embedded near the surface of a non-photoluminescent tile base.

FIG. 10 is a sectional view of a floor tile in accordance with yet another embodiment of the present invention, in which photoluminescent chips are embedded near the surface of a non-photoluminescent tile base.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Photoluminescent Tiles having Photoluminescent Material Throughout the Tile Base

The present invention provides a rigid, non-transparent building material that incorporate photoluminescent material, including particles or chips of material having photoluminescent particles in the chips. The building material is durable and provides long-lasting illumination when the ambient light is removed. While the building material of the present invention can be manufactured in a variety of shapes and dimensions, it is preferred that the material be formed into tiles for easy installation as flooring or wall material.

FIGS. 1-3 show one embodiment of the present invention wherein photoluminescent particles 16 are disbursed throughout a tile base 18 to provide a photoluminescent tile 10. The portion of the photoluminescent particles present on the top surface 12 of the photoluminescent tile 10 is attributable for absorbing and storing the light from and for emitting luminescence to the ambient environment.

As used herein, “tile base” or “tile base composition” refers to a non-photoluminescent tile composition into which a photoluminescent material, including particles or chips can be incorporated. The tile base typically comprises an inorganic filler and an thermoplastic binder system. “Inorganic filler” refers to a non-transparent mineral material. Typically, the inorganic filler can be crushed or ground limestone or ground clay. Generally speaking, the amount of the inorganic filler is at least half or a substantial portion of the total weight of the tile base to impart the necessary rigidity.

“Thermoplastic binder system”, also referred as the “vinyl resins”, refers to a largely organic composition including resins, plasticizer and stablizer. The thermoplastic binder system can be softened and melted at high temperature and cooled down to harden. At the molten stage, the binder system can be mixed thoroughly with the inorganic filler and/or photoluminescent material. The malleable mixture can then be processed, rolled or calendared. While cooling down, the mixture hardens and fuses together. Due to the thermoplastic nature of the binder system, the above process can be repeated infinitely without substantially affecting the material property of the binder. As will be discussed below in more details, the thermo-reversibility of the thermoplastic binder thus enables the recycling of the defective or broken tiles by re-incorporating them into a later batch of the tile production.

Suitable resins for the binder system include polyvinyl chloride (PVC) homopolymer, polyvinyl chloride/poly vinyl acetate (PVA) copolymer or a mixture thereof. The molecular weights of the polymer components are typically in the range of 55-60K Dalton. Compared to the PVC/PVA copolymer, PVC homopolymer is generally regarded by one skilled in the art as being tougher which provides the impact resistance. The PVC/PVA copolymer, on the other hand, processes better and fuses at lower temperature. It is therefore preferred to use a mixture of the PVC homopolymer and PVC/PVA copolymer in order to exploit their respective characteristics and optimize the products' processing and physical properties. Typically, the mixture comprises low molecular weight PVC homopolymer (55-58K) and high molecular weight PVC/PVA copolymer (58-60K).

As used herein, “plasticizer” refers to a type of chemicals that modify the crystalline and often brittle vinyl resins by making them more plastic or flexible. Plastizers work by increasing the free volume available to the polymer chain segments which increases the rotational and translational motion of the resin chains. In addition, the plasticizers reduce the polymer to polymer interactive forces thereby making the polymeric chains more flexible. For purpose of this invention, phthlate plasticizers, including butylbenyzylphthalate (BBP or S-160), and diisononylphthalate (DINP) maybe be used.

As noted above, in order to obtain a rigid tile base, the inorganic filler accounts for about 50-95 wt % of the total weight of the tile base, whereas the thermoplastic binder system accounts for 5-50 wt % of the total weight of the tile base. As a general rule, the more inorganic filler is incorporated, the more rigid and brittle the finished tile base is, and the more difficult it is to process. Conversely, the more thermoplastic binder system, the less rigid the tile base is and the easier to process. Generally speaking, the inorganic filler amounts to 50-95 wt % of the total weight of the tile base. More typically, the inorganic filler is 60-90 wt % of the total weight of the tile base. Even more typically, the inorganic filler is 70-85 wt % of the total weight of the tile base.

The non-photoluminescent tile base composition as described above is sometimes referred as “Vinyl Composition Tiles” (VCT) in the tile manufacturing industry.

The “photoluminescent material”, as used herein, refers to photoluminescent particles or photoluminescent chips.

“Photoluminescent particles”, as used herein, refer to non-radioactive photoluminescent pigment. One suitable pigment comprises rare earth materials. These photoluminescent pigments are each characterized by low toxicity, short excitation time, high brightness and long illuminating life. One example of a suitable pigment is strontium aluminate having a europium activator. It is commercially available in different colors as Series G-200, Y-200, B-200 or V-200 from Way2glo, Inc., Thousand Oaks, Calif.

The photoluminescent particles of the present invention are fine powders with average dimension of about 30 μm. Thus, in the first embodiment of the present invention, photoluminescent particles are mixed thoroughly with the inorganic filler and thermoplastic binder system to provide a photoluminescent tile 10.

Because the photoluminescent particles are inorganic material themselves, the combined weight of the particles and inorganic fillers can comprise between 50-95 wt % of the total weight of the tile 10 in order to form a rigid glowing tile. More typically, the combined weight of the particles and the inorganic filler is 60-90 wt % of the total weight of the tile base. Even more typically, the combined weight of the particles and the inorganic filler is 70-85 wt % of the total weight of the tile base.

The amount of the photoluminescent particles in the tile 10 determines the brightness and duration of the photoluminescence emitted from the tile. Typically, in order for the tile to have sufficient amount of the particles to give off a visible illumination in the dark, at least 10 wt % of the total weight of tile 10 is consisted of the photoluminescent particles. The amount of the photoluminescent material can go up to 90 wt % of the total weight of the tile 10. Economic considerations, however, may dictate that between 15-40 wt % of the photoluminescent particles can be incorporated to ensure a satisfactory brightness and duration of the illumination. More typically, about 20 wt % of the total weight of tile 10 is consisted of the photoluminescent particles.

The main ingredients, including the inorganic fillers, thermoplastic binder system and the photoluminescent particles can be placed in a shearing mixer and are thoroughly mixed. This ensures that the photoluminescent particles 16 are distributed evenly throughout the mixture. Optionally, non-photoluminescent color pigments can also be incorporated. The mixer heats the ingredients to about 280° F. The heated mixture is discharged from the mixer and passes through a roll mill to form a blanket. The blanket is about 200 mils (0.2 inch) thick. More typically, the blanket is about 80-130 mils (0.1 inch) thick for commercial grade tiles. The blanket is then heated and rolled several times to partially cross-link the polymeric ingredients in the thermoplastic binder system and form a finished gauge blanket. If desired, a wax or urethane overcoating or other surface treatment can be applied. The sized and finished blanket is then transferred to a press that punches individual tiles 10 from the blanket.

The tiles 10 are installed in the same manner as any type of commercial floor tile, particularly VCT tiles. This enables a photoluminescent backup system to be installed simultaneously with floor installation, without additional labor.

The photoluminescent particles 16 on the top surface 12 of the tile 10 absorb light from the ambient lighting, including sunlight, fluorescent or incandescent lightings. During a blackout, they are capable of releasing the light and supplement backup lighting. Less than 1 hour of light exposure is typically sufficient to charge the photoluminescent particles.

FIGS. 4a and 4b show a second embodiment of the present invention wherein photoluminescent chips 116 are embedded evenly throughout a tile base 18 to provide a photoluminescent tile 110.

“Photoluminescent chips”, as used here, refer to small pieces of aggregates of photoluminescent particles. For purpose of this invention, there are essentially two types of photoluminescent chips. In one aspect, the photoluminescent chips are ground-up or crushed photoluminescent tile 10. Each chip therefore has the same composition of a photoluminescent tile according to the first embodiment of the invention. The photoluminescent chips are typically about 2-20 mils in dimensions. More typically, they are about 2-10 mils in dimensions. In another aspect, the photoluminescent chips comprises only photoluminescent particles and the thermoplastic binder system, no inorganic filler is present. In this aspect, the photoluminescent particles comprise about 50-95 wt % of the weight of each chip, whereas the thermoplastic binder system comprise about 5-50 wt % of the weight of each chip.

The photoluminescent chips are mixed thoroughly with a tile base composition, i.e., the inorganic filler and the thermoplastic binder system, to form a photoluminescent tile. Typically, the chips are added into a heated, well-mixed tile base composition. The chips are then mixed for a short period of time to ensure that the chips are disbursed throughout the tile base.

Typically, the photoluminescent chips comprise about {fraction (1/5)}-{fraction (3/4)} of the total weight of the tile 110. More typically, the photoluminescent chips comprise about ⅓ of the entire tile 110 to ensure sufficient amount of the chips on the top surface of the tile.

In addition to providing the illumination, the photoluminescent chips also endow the tile 110 with varied appearances such as the striated patterns (shown in FIG. 4a) and the marbled patterns (shown in FIG. 4b). The different appearances in patterns can be controlled by the processes by which the photoluminescent chips are mixed with the tile base composition. More specifically, the duration of the mixing of the chips with the tile base composition determines the appearance of the finished tile. The longer the chips are mixed with the heated tile base composition, the softer and more pliable the chips become and the easier they can be reshaped when the tile blanket is rolled out. For example, when the photoluminescent chips are mixed together with the tile base composition at high temperature for 80 seconds, the chips become more pliable due to the partial melting of the thermoplastic binder which softens the formerly rigid and cross-linked structure. When the tile mixture is rolled out into a blanket, the chips embedded therein are reshaped and tend to be elongated, hence provides the striated pattern on the tile surface (FIG. 4a). When the chips are mixed for only 40 seconds, they are less likely to be radically reshaped. At the same time, the heat is sufficient to reduce and round out the irregularities of the edges of each chip. The rolled out tile therefore tend to have a marbled pattern (FIG. 4b).

Colored, non-photoluminescent pigments in the forms of powders or chips, that are common decorative additives to a tile composition can be optionally added to the tile mix for making the photoluminescent tiles 10 to enhance the diversity of the appearance of the tiles or the photoluminescent chips made therefrom. These colored pigments are commercially available from, for example, Bayer Chemicals and Du Pont Industry.

The photoluminescent tiles according to the first and second embodiments have the rigidity and mechanical strength that meet the industry standard. The incorporation of the photoluminescent material into the tile base enable the tiles to illuminate in the dark. Because the photoluminescent material is disbursed throughout the tile base, fresh photoluminescent material is always available on the surface despite heavy wears in the tiles.

The photoluminescent tiles 10 and 110 can be installed in exactly the same manner as any commercially available tiles. As noted above, their mechanical properties are particularly close to the non-photoluminescent vinyl resin based VCT tiles, such as those commercially available from Congoleum Inc., Armstrong World Industry and Manington Inc. Accordingly, each photoluminescent tile typically has the same appearance of a non-photoluminescent VCT tile under normal ambient lightings. These photoluminescent tiles can be combined with non-photoluminescent VCT tiles during installation to form versatile patterns or signs. A floor laid with both the photoluminescent and non-photoluminescent tiles which may appear to be an uniform floor under normal lighting, will instantly produce a variety of glowing patterns in a dim light or complete darkness. The patterns include bond patterns, checkerboard patterns, geometric shapes, words or borders. This feature is particularly useful in guiding people to exists in public buildings, such as hospitals, hotel lobbies or the like. It may also be used to provide decorative or entertaining patterns for venues such as dance floors, skating rinks, sidewalks and convention centers.

FIG. 5 illustrates a floor forming a portion of an escape route. The floor includes a number of floor tiles 10 (each shown with an “X”) and non-photoluminescent tiles 20. The floor appears to be an uniform floor under normal lighting. In a blackout, the tiles 10 illuminate an area surround by the dark tiles 20. In addition to illuminating an escape route, the tiles 10 can be arranged to provide useful indicia. In FIG. 5, the tiles 10 are arranged to define an arrow indicating direction along the escape route.

FIG. 6 further illustrates a floor in which photoluminescent tiles 10 are combined with non-photoluminescent tiles 20 to form an interlocked herringbone patter. Likewise, photoluminescent tiles 110 can be combined with the non-photoluminescent tiles 20 in the same manner as illustrated in FIGS. 5-6.

Photoluminescent Tiles having Wear Layers

Because photoluminescent material are costly, the incorporation of which throughout the entire tile base may become economically unfeasible in spite of the incremental benefit of having fresh photoluminescent material always available on the surface of even severely worn tiles. Thus, the present invention further provides photoluminescent tiles having a wear layer, wherein, a photoluminescent material is present only in the wear layer. These photoluminescent tiles can withstand normal wear and tears within the limitation of the thickness of the wear layer to ensure a reliable and continuous illumination during the tile's useful life. The cost of these tiles, due to the reduction of the material cost associated with the photoluminescent particles, become more reasonable and comparable to other specialty tiles.

The term “wear layer”, as used herein, refers broadly to a layer that constitutes an upper portion of a photoluminescent tile of the present invention. In detail, the wear layer is, with or without further surface treatment, the portion of the photoluminescent tile that is exposed to the ambient environment after installation. The wear layer comprises a tile base composition having a photoluminescent material, including photoluminescent particles and photoluminescent chips, disbursed throughout. As will be discussed in more details below, the wear layer can be a layer that is processed separately and affixed to a non-photoluminescent substrate, such as a tile base. Alternatively, the wear layer is an integral part of the tile and is formed by pressing photoluminescent material into a depth within a tile base.

Thus, in a third embodiment, the present invention provides a photoluminescent tile comprising a tile base bonded with a wear layer, wherein the wear layer including photoluminescent particles disbursed evenly throughout. As shown in FIG. 7 (not drawn to scale), a wear layer 220 overlies a substrate 212 to provide a photoluminescent tile 210. Photoluminescent particles 16 are only present in the wear layer 220. Essentially, this type of photoluminescent tile combines a non-photoluminescent substrate with the photoluminescent tile of FIGS. 1-3 to provide a rigid tile having photoluminescent particles contained only in the upper portion of the finished tile. Optionally, a top surface of the wear layer can be treated with a transparent overcoating 214.

The composition of the wear layer 220 is the same as the photoluminescent tile as described in association with FIGS. 1-3. The wear layer 220 thus comprises the tile base 18 and photoluminescent particles 16. The substrate 212 can be a non-photoluminescent tile base, which composition is as defined and described above.

Because the wear layer and the tile base are processed separately, their respective compositions and thicknesses can be controlled and customized while taking into consideration of factors such as but not limited to: the overall thickness of the finished tile, any specific requirement for the thickness of the wear layer, any cosmetic or special surface treatment for the wear layer. Typically, about {fraction (1/10)} to ⅘ of the entire thickness of the finished photoluminescent tile can be the wear layer. More typically for commercial tiles of 80-100 mils in overall thickness, the wear layer is about 10-20 mils thick.

The wear layer and the tile base are bonded or fused together by heating, calendaring or any other methods generally known to one skilled in the art. Although the tile base and the wear layer are processed and manufactured independently of each other before they are fused together, it is advantageous that they possess similar degree of rigidity to ensure the structural integrity of the finished tile throughout its useful life.

A forth embodiment of the present invention provides a photoluminescent tile comprising a tile base bonded with a wear layer, wherein the wear layer including photoluminescent chips disbursed evenly throughout. As shown in FIG. 8 (not drawn to scale), a wear layer 320 overlies a substrate 312 to provide a photoluminescent tile 310. Photoluminescent chips 116 are only present in the wear layer 320. Essentially, this type of photoluminescent tile combines a non-photoluminescent substrate with the photoluminescent tiles of FIGS. 4a and 4b to provide a rigid tile having photoluminescent chips contained only in the upper portion, namely the wear layer, of the finished tile.

The composition of the wear layer is the same as the photoluminescent tile as described in association with FIGS. 4a and 4b. The composition of the substrate can be that of a tile base and is as defined and described above.

Because the wear layer and the tile base are processed separately, their respective compositions and thicknesses can be controlled and customized while taking into consideration of factors such as but not limited to: the overall thickness of the finished tile, the dimension of the photoluminescent chips, any specific requirement for the thickness of the wear layer, any cosmetic or special surface treatment for the wear layer. For example, the composition of the wear layer can be separately selected to provide high mechanical strength for long lasting usage when exposed to foot traffic or other external environment. Typically, about {fraction (1/10)} to ⅘ of the entire thickness of the finished photoluminescent tile can be the wear layer. More typically for commercial tiles of 100 mils in overall thickness, the wear layer is about 10-20 mils thick.

The wear layer and the tile base are bonded or fused together by heating, calendaring or any other methods generally known to one skilled in the art. Although the tile base and the wear layer are processed and manufactured independently of each other before they are fused together, it is advantageous that they possess similar degree of rigidity to ensure the structural integrity of the finished tile throughout its useful life.

A fifth embodiment of the present invention provide a photoluminescent tile comprising a tile base having a top surface, and photoluminescent particles embedded into a depth within the tile base thereby providing a wear layer, the photoluminescent particles covering at least 10% of the top surface of the tile.

The composition of the tile base is as described above. As shown in FIG. 9 (not drawn to scale), in a photoluminescent tile 410, the photoluminescent particles 16 are embedded into a depth of D within the tile base 18. The photoluminescent particles 16 are on or near the top surface 430, thus forming a wear layer 420.

Unlike the photoluminescent tiles having wear layers separately processed before being affixed to a non-photoluminescent substrate, this embodiment provides a wear layer that does not have a well-defined boundary where the wear layer ends within the tile base. However, this does not prove to be a drawback. Depends on the thickness of the photoluminescent particles deposited on the surface of the tile blanket, the depth D can be typically controlled at between 2-20 mils, and more typically between 2-10 mils, which are within the satisfactory thickness for a wear layer.

To form the photoluminescent tile 410, the tile base composition are mixed and formed into a blanket as in making a non-photoluminescent tile. Before the blanket is cooled off, the photoluminescent particles 16 are dusted or otherwise distributed on the top surface of the blanket. The dusted blanket is rolled to embed and disburse the particles into a depth of D within the upper portion of the blanket. Optionally, non-photoluminescent color chips can be dusted and embedded into the tile base along with the photoluminescent particles 16. The finished gauge blanket can be then optionally subjected to a surface treatment and the tiles are punched from the blanket as previously described. Depending on the amount of the photoluminescent coverage desired on the top surface of the tile and the thickness of the wear layer, the photoluminescent particles can be dusted on the entire surface or only in space-apart areas. The patterns of the particle distributions also provide versatility to the surface appearances.

Advantageously, in this embodiment, the wear layer is not technically a separate layer from the tile base as to require an additional step of rolling out a separate photoluminescent tile blanket. Rather, the wear layer is formed during the same process of forming the tile base blanket. As a result, both the labor and material cost are reduced.

A sixth embodiment of the present invention provides a photoluminescent tile comprises a tile base having a top surface, and photoluminescent chips embedded into a depth within the tile base thereby providing a wear layer, the photoluminescent chips covering at least 10% of the top surface of the tile.

The composition of the tile base is as described above and the composition of the photoluminescent chips are as previously defined. As shown in FIG. 10, in a photoluminescent tile 510, photoluminescent chips 116 are embedded into a depth of D within a tile base 18. The photoluminescent particles 116 are on or near the top surface 530, thus forming a wear layer 520.

Similar to the previous embodiment, this type of tile does not require a separate process of forming a discrete wear layer. Rather, the photoluminescent chips are sprinkled onto the top surface of a tile base blanket before it is cooled off. The chips are then pressed and rolled into the tile base thus forming a wear layer. Optionally, non-photoluminescent color chips can be embedded into the tile base along with the photoluminescent chips.

Depends on the amount and dimension of the photoluminescent chips sprinkled on top of a tile blanket, the depth D can be typically controlled at between 2-20 mils, and more typically between 2-10 mils.

The present invention is now illustrated by the following non-limiting examples.

EXAMPLES

Example 1

A representative photoluminescent tile 10 has the following formulation, in which the photoluminescent particles constitute 20 wt % of the total weight of the finished tile.

TABLE 1
IngredientsAmount (pounds)
inorganic fillersground limestone (60 mesh)163
ground limestone (80 mesh)195
thermoplastic binderacetate vinyl resin17
systemstabilizer1
vinyl resin23
plasticizer16
photoluminescentphotoluminescent particles106
material

Example 2

In the process of tile production, a main source of waste tiles originates from the remainder of a tile blanket after the tiles have been punched out. Other sources include defective or broken tiles off a production line. These waste tiles are almost invariably recycled and are referred in the industry as “line remix” or “line dust”. As previously discussed, because the thermoplastic binder system is thermally reversible, the waste tiles can be reincorporated into a subsequent production line. When they are mixed with the fresh ingredients at high temperature in the next production, the recycled tiles soften and become miscible with the other ingredients due to the disintegration of the polymeric cross-linking network. The mixture will then be processed into a new tile blanket.

Because the recycled tiles often contain photoluminescent particles from a previous batch of tile-production, a reformulation of the production line into which the recycled tiles are incorporated may be warranted. The principle concern is one of economics. Photoluminescent particles are costly and it is desirable to only use an amount that is necessary to provide sufficient illumination. For example, it has been found that when the weight of the photoluminescent particles is about 20 wt % of the total tile weight, as represented by the formulation in Example 1, there is sufficient amount on the tile surface to ensure an enduring illumination. When the recycled tiles from the production line of Example 1 is reincorporated into a subsequent production line, if the overall weight remains the same, less than 106 pounds of photoluminescent material is needed to produce photoluminescent tiles having 20 wt % photoluminescent material.

Table 2 below illustrates a new formulation, wherein the overall weight of the material remains the same as that in Example 1.

TABLE 2
IngredientsAmount (pounds)
inorganic fillersground limestone (60 mesh)122
ground limestone (80 mesh)154
thermoplastic binderacetate vinyl resin17
systemstabilizer1
vinyl resin23
plasticizer16
recycled tiles*line remix65
line dust37
photoluminescentphotoluminescent particles86
material

*The tiles are recycled from the production line of Example 1 or Example 2.

All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety.

From the foregoing, it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.