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BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention has to do with surface covering tiles that can be connected to one another by means of an edge treatment that allows for grouting after the tiles are assembled. In a preferred embodiment, the invention relates to a flooring tile that can be assembled and grouted without adhesion to a sub-floor. The invention also concerns a process of manufacturing the tile product and a method of installing the product. 
     2. The Related Art 
     Various constructions for floating floor coverings and for connecting surface covering tiles to one another have been described in the art. 
     In Published Patent Application No. US2003/0131549, for example, a tile having a wearing layer and a support layer is described wherein the support layer has projections and mating cutouts. The projections and cutouts are hidden by the wearing layer when the tiles are installed. The installed tiles have narrow joints between individual tiles to allow welding so that dirt cannot adversely affect the flooring. 
     U.S. Pat. No. 5,791,114 discloses tiles having projections and mating cutouts that are virtually identical to those disclosed in the published application discussed above. A beveled edge is provided on the underside of the projections to facilitate installation. Unlike the published application discussed above, the projections and mating cutouts are not hidden when the tiles are installed. 
     In U.S. Pat. No. 7,610,731, a snap-together floor structure is described which requires a tray, a flooring material, a rubber grommet and a rubber matrix. The invention provides a floating floor structure that can be assembled without the use of adhesives on the subfloor. 
     A modular surface for use as a sports deck is described in U.S. Pat. No. 4,436,779. Modules for a non-anchored modular surface are described which employ an expansion joint geometry adapted to retain the square shape of each module. This permits a surface including a large number of interlocked modules to remain flat and unbuckled with changing temperature conditions. 
     Resilient floor tiles having a convex edge are described in U.S. Pat. No. 7,550,192. The objective of the design is to simulate ceramic and natural tile floors. The tiles are installed conventionally by adhering them to a sub-floor. Installed tiles can be spaced from one another to permit installations using grout. 
     SUMMARY OF THE INVENTION 
     The tiles of the invention, when assembled by connecting them to one another, do not require adhesion to the underlying surface. In the case of flooring, the assembled tiles are used to make a floating floor. When the tiles are used to cover walls, they can be adhered to the underlying surface using conventional adhesives. 
     Each tile is constructed with integral junction strips which allow adjacent tiles to be connected to and interlocked with one another. The junction strips are sized so that the upper decorative surfaces of adjacent tiles are evenly spaced from one another to permit the application of grout or the incorporation of simulated grout in the spaces between the decorative surfaces. 
     Conventional materials used in the manufacture of tiles containing plastics, such as resilient tiles, are used to make and decorate the tiles of the invention. Adhesives can optionally be applied to the junction strips either during manufacture or in the field to securely affix the tiles to one another. Grout material applied in the field can also serve as the adhesive or as a supplemental adhesive. 
     All percentages set forth herein are by weight/weight unless otherwise designated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a section view of a tile of the invention. 
         FIG. 2  is a partial section view of two tiles of the invention. 
         FIG. 3  is a partial section view of two tiles of the invention which have been assembled. 
         FIG. 4  is a partial section view of a preferred embodiment of two tiles of the invention. 
         FIG. 5  is a view of the top of a tile of the invention. 
         FIG. 6  is a view of the bottom of a tile of the invention. 
         FIG. 7  illustrates the top of a portion of one tile overlayed by the bottom of a portion of another tile. 
         FIG. 8  is a top view of three rectangular tiles which have been assembled according to the invention. 
         FIG. 9  is a top view of a hexagonal tile of the invention. 
         FIG. 10  is a top view of a combination of four octagonal tiles and three square tiles which have been assembled according to the invention. 
     
    
    
     The drawings are not intended to be to scale. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A tile  1  (or tile substrate as described with reference to  FIG. 4 ) is illustrated in section in  FIG. 1 . The tile has an upper tile surface  2  and an opposing lower tile surface  3 .  FIG. 2  illustrates, in section, portions of two tiles, designated as  1   a  and  1   b , each having a thickness t, and the tiles are positioned so that they can be assembled by moving tile  1   b  downwardly in the direction D. 
     Referring to  FIG. 1 , the upper tile surface  2  has side edges  4  and  4   a . Extending from the right-hand side edge  4  is a lower junction strip  6 . The lower junction strip  6  has an upper face  8  and an opposing lower junction strip surface  9 . The lower junction strip surface  9  being a portion of and included within the lower tile surface  3 . The upper face  8  is comprised of a first raised portion  12  and a first channel  14 . The first channel  14  has a first width defined by side edge  4  and first inner edge  15  of first raised portion  12 . The side edge  4  and first inner edge is  15  are in parallel. The first raised portion  12  has a second width defined by first inner edge  15  and lower junction strip outer edge  5   a . Lower junction strip outer edge  5   a  is the same as the right-hand lower side edge of the tile. Element  20  within first channel  14  is optional. It can be an optional decorative portion which simulates grout or it can be an optional grout base which enhances the adherence of grout that is applied after the tiles are installed. 
     Further referring to  FIG. 1 , the lower tile surface  3  has side edges  5  and  5   a . Extending from the left-hand side edge  5  is an upper junction strip  7 . The upper junction strip  7  has a lower face  10  and an opposing upper junction strip surface  11 . The upper junction strip surface  11  being a portion of and included within the upper tile surface  2 . The lower face  10  is comprised of a second raised portion  16  and a second channel  17 . The second channel  17  has a third width defined by side edge  5  and second inner edge  18  of second raised portion  16 . The side edge  5  and second inner edge  18  are in parallel. The second raised portion  16  has a fourth width defined by second inner edge  18  and upper junction strip outer edge  4   a . Upper junction strip outer edge  4   a  is the same as the left-hand upper side edge of the tile. 
       FIG. 3  illustrates the tiles of  FIG. 2  after they have been assembled. Both of the upper tile surfaces  2  are in the same upper tile surface plane. And both of the lower tile surfaces  3  are in the same lower tile surface plane. The upper and lower tiles surface planes are parallel planes. When the tiles are assembled, element  20  is uncovered and visible from eyes  21  looking down upon the upper tile surfaces  2 . 
     Referring to  FIGS. 1-3 , the first raised portion  12  of the lower junction strip  6  has a thickness less than the thickness t of the tile and is sized to fit within and interlock with the second channel  17  of the upper junction strip  7 . The second raised portion  16  of the upper junction strip  7  also has a thickness less than the thickness of the tile and the fourth width of the second raised portion  16  is less than the first width of the first channel  14  of lower junction strip  6 . Thus, when the tiles are assembled as illustrated in  FIG. 3  there is a space between side edges  4  and  4   a . And this space permits the optional addition therein of decorative elements such as grout or elements having the appearance of grout. 
     Typical dimensions of the tile of  FIGS. 1-3  would include an overall thickness t of 180 mils. Edges  4  and  4   a  each have a thickness of 100 mils, edges  5  and  5   a  each have a thickness of 125 mils and edges  15  and  18  each have a thickness of 47 mils. The widths of first raised portion  12  and second channel  17  are the same at 245 mils. And the widths of lower raised portion  16  and the space between element  20  and edge  15  are the same at 240 mils. The total width of first channel  14  is 490 mils. 
     Adhesives  30  can optionally be used to attach the tiles to one another. The adhesives  30  can be applied to the first and/or second raised portions and/or the first and/or second channels. If adhesive  30  is applied to the first channel, it preferably should not be applied to the portion of the channel that is visible when the tiles are installed. The adhesives  30  can be applied when the tiles are manufactured or in the field. It is preferable to apply the adhesive  30  to second channel  17  because the adhesive  30  then is hidden when the tiles are installed. And if adhesive  30  is applied to second channel  17  during manufacture, there is no need to apply release paper which then would need to be removed in the field. If adhesive  30  is applied during manufacture to a raised portion, such as first raised portion  12 , then release paper also must be applied over the adhesive  30 . Various types of adhesives can be used, for example, hot melt adhesives or water borne acrylic that has been dried to a tacky state. Other suitable adhesives can be used as will be apparent to those having skill in the art. As noted above, grout material applied in the field can also service as the adhesive or as a supplemental adhesive to those described above. 
     A preferred embodiment of the tile is illustrated in  FIG. 4 . The preferred embodiment has optional added elements which may be employed individually or in various combinations as will be apparent to those having skill in the art. These elements can be added to the basic tile construction which is discussed above in respect of  FIGS. 1-3 . 
     In  FIG. 4 , the tiles are comprised of a substrate  22  overlayed by a decorative layer  23 . The decorative layer  23  is overlayed by a performance top coating  24  which in turn is overlayed by a protective layer  25 . The tiles are optionally beveled at edge  26 . Edge  26  can have other shapes, such as convex or concave rounding and the like, as design options that will be apparent to those having skill in the art. The decorative layer can be any kind of decoration commonly used in tiles of the type described herein including printed layers comprised of inks and/or plastics, wood or simulated wood veneers, metals and the like. 
     Turning to the underside of the tile, a back layer  27  is illustrated. 
     The various layers and the substrate can be adhered to one another by laminating or other manufacturing techniques known to those having skill in the art. 
     Upper reinforcements and lower enforcements are designated by reference numerals  28  and  29  and these are recommended for use in thinner tiles. The reinforcements can be made, for example, from a mesh or textile material which is impregnated into the substrate  22  in a conventional calendering operation. The kinds of reinforcement materials used at  28  and  29  are known in the art and can be the same or different. Suitable materials include polyester fleece, a scrim such as Porche-Chavanoz D12155093 2×2 yarn/cm or a glass fleece such as Ownens Corning AH 24. When a glass fleece is used at  28 , it needs to be impregnated with plastisol before laminating a decorative layer thereon. 
       FIG. 5  is a top view of tile  1  of the invention. The figure illustrates, among other elements, upper the surface  2 , first raised portions  12  and optional elements  20 . First corner raised portion  12   a  is optional and it can be employed to enhance the structural integrity of the tiles when they are assembled. 
     A bottom view of tile  1  is illustrated in  FIG. 6 . The figure illustrates, among other elements, lower tile surface  3 , second raised portions  16  and channels  17 . Second corner raised portion  16   a  is optional and serves the same purpose as first corner raised portion  12   a.    
       FIG. 7  illustrates the underside of a tile portion partially overlaying the top side of another tile portion. The figure provides a side-by-side comparison of the upper and lower junction strips. 
     In  FIG. 8 , three assembled rectangular tiles  101  having upper tile surfaces  102  are illustrated in a top view. First raised portions  112  and optional decorative portions or grout base  120  are illustrated. The upper junction strip outer edges  104   a  designate the edges of the upper junction strips which face downwardly from the tops of the tiles in the same manner and having the same construction as the upper junction strips of the tiles discussed in respect of  FIGS. 1-3  above. Outer edges of the lower junction strips are designated as  105   a.    
       FIG. 9  is a top view of hexagonal tile  201  having an upper tile surface  202 . First raised portions  212  and optional decorative or grout base portions  220  are illustrated. The upper junction strip outer edges  204   a  designate the edges of the upper junction strips which face downwardly from the top of the tile in the same manner and having the same construction as the upper junction strips of the tiles discussed in  FIGS. 1-3  above. One of the principles of the invention is that the tiles need to have an even number of sides. One half of the side edges of the upper tile surface have adjacent lower junction strips extending therefrom and the other half of the side edges have adjacent upper junction strips extending therefrom. The upper junction strips and lower junction strips extend from opposing side edges. Thus, in hexagonal tile  201 , three of the upper junction strips extend from adjacent side edges opposite the three side edges from which the lower junction strips extend. The outer edges of the lower junction strips are designated as  205   a.    
       FIG. 10  illustrates a combination of assembled octagonal and square tiles in a top view. Octagonal tiles  301  are assembled with square tiles  1 . In the octagonal tiles there are four adjacent lower junction strips having outer edges designated as  305   a  and there are four adjacent upper junction strips on the undersides of the tiles having outer edges designated as  304   a . Of course, the lower junction strips have the same construction as those discussed above. The first raised portions are designated as  312  and optional decorative or grout base portions are designated as elements  320 . 
     The tiles of the present invention are made using synthetic materials but they can be decorated to imitate ceramics, concrete, glass, bricks, adobe, textiles or metals. They can also be decorated to imitate natural materials such as marble, granite and wood. Other design options will be apparent to those having skill in the art. The preferred tiles of the invention are resilient tiles which have a certain degree of flexibility or resiliency. Materials used to make a resilient floor tile may include organic materials, such as polymeric materials, including, for example, vinyl or mixtures of organic and inorganic materials. Thus, a substrate of the tiles of the invention may be made of any material useful in making a resilient tile. For example, the substrate may comprise a mixture of limestone and a polymeric resin and may also include plasticizers and pigments. More specifically, the polymeric resin may be a copolymer or a homopolymer. Specific examples of base compositions include a final composition that includes limestone, acetate, polyvinylchloride resin, plasticizer and, optionally, pigments, where the organic materials function as a binder for the limestone. Alternatively, the substrate may be a vinyl composition that includes limestone, polyvinylchloride homopolymer, plasticizer, and, optionally, pigments, where the organic materials also function as a binder for the limestone. 
     The substrate contributes significantly to the overall flexibility of the resilient tile. While any material may be used as the substrate, it is preferred that the substrate composition and, therefore, the overall resilient tile, have some rigidity and not be completely flexible, such as a rubber the or solid vinyl tile. Since the binder content of the substrate affects the level of rigidity of the overall resilient tile, it is preferred that the total organic content or binder content of the substrate be from about 20% to about 40% by weight. Three typical formulations for the substrate of the invention are (1) 23% resin, 7% plasticizer, 67% calcium carbonate and 3% pigments and stabilizers, (2) 30% resin, 8% plasticizer, 59% calcium carbonate and 3% pigments and stabilizers, and (3) 38% resin, 12% plasticizer, 47% calcium carbonate and 3% pigments and stabilizers. At lower resin contents, such as 23%, the tiles may chip somewhat when routing is used as the method of forming the junction strips of the invention. This can be avoided if the tiles are formed using molding rather than grouting. 
     Various tile thicknesses can be used and thicknesses from about ⅛ inch to ¼ inch are not uncommon. In thinner tiles, however, mesh or textile reinforcements need to be impregnated into the upper and lower surfaces of the substrate in order to prevent the junction strips from breaking off. 
     The shapes and sizes of the tiles can be varied depending upon design needs as will be apparent to those having skill in the art. 
     In a typical manufacturing process, raw materials for the substrate are fed into a continuous mixer and the output of material from the mixer is conveyed to an extruder. It is extruded through a roller head die into a calendar. The calendar produces a web at the desired thickness. Sheet is conveyed to an embossing station where a texture is applied and a vinyl film with a pattern and a clear wear layer is laminated to the substrate. The web is then cooled, coated with a urethane coating, cut into oversize blanks, annealed, cooled, and die cut. The die cut tiles are then palletized and taken to the finishing department. The tiles are then loaded into a beveler (router) and conveyed through the beveler into the first junction routing station that routes one edge of the top side to make a lower junction strip and trim the junction strip outer edge. Immediately following the routed edge and the opposite edge are crimped (i.e., the edges are rolled to provide a radius on the edges of the decorative surfaces next to the grout line) and/or an imitation grout line is embossed. From this point the tile is turned 90 degrees and the next lower junction strip is routed followed with the crimping and/or embossing process of the remaining two edges. The next step is to route the adjacent junction strips on the bottom of the tiles to make the upper junction strips and trim the junction strip outer edges. Then the tiles are conveyed to the adhesive application station where adhesive and release paper are applied to the junction strips if needed (some tiles will require hot melt adhesive applied at this time, others will have adhesive applied in the field and some will not require any adhesive), The tiles then proceed to the flip/stack/packaging equipment where they are prepared for warehousing and/or shipping. 
     EXAMPLE 
     Square tiles imitating the appearance of ceramic and having finished dimensions of 16 inches by 16 inches and a thickness of 0.175-0.180 inches were made in two runs, one with a binder content of 30% and the other with a binder content of 38%. The 30% binder tiles had a Shore D hardness of 64 and a specific gravity of 1.82-1.86. The 38% binder tile had a Shore D hardness of 63 and a specific gravity of 1.70-1.75. Scrap was used as a portion of the raw materials in making up the substrate formulation. The manufacturing process set forth above was followed using calendar roll temperatures of 250° F. to 260° F., a urethane entry temperature from 130° F. to 152° F. (using six UV lamps) and a film heat of 110° F. to 115° F. The temperature entering the embosser was at 325° F.-330° F. and the cooling pan entering temperature was set at 294° F. A backing having the same composition as the substrate was also laminated onto the underside of the substrate. The edges of the decorative layer were beveled by crimping and a router was used to form the junction strips. No chipping was observed as a result of crimping and routing the tiles of either binder content. 
     Various materials may be used to prepare a decorative pattern or design for application to the tile. The decorative layer may be a printed ink that provides a decorative pattern or design or the layer may be a plurality of particles or chips of various solid materials, such as wood, textiles, metals or plastics that are disposed on top of or embedded in the top of the substrate. These materials may also be used in combination with a printed ink. 
     Transparent performance topcoatings may also be applied over the decorative layer. A performance topcoating may be made from a polymeric film, such as polyvinylchloride. 
     A protective layer also may be applied on top of the performance topcoating. The protective layer may comprise a polymeric film, such as a urethane film that is cured using ultraviolet radiation. The protective layer is designed to protect the performance topcoating and the decorative layer. The protective layer also may comprise additional components, such as particles including, for example, aluminum oxide or nylon and it may have visible texture. The protective layer also may be applied directly over the decorative layer if a performance topcoat is not used.

Summary:
Surface covering tiles made using synthetic materials employ junction strips which enable the tiles to be connected to one another. The connections can be made with or without adhesive. When the tiles are connected, a space is left between adjacent decorative surfaces to permit the application of grout or simulated grout therein. When the tiles are used as floor covering they can be used to make floating floors. As wall coverings, the tiles are adhered to the walls using conventional means.