Injection molded floor tiles with drainage vents

Abstract

Modular plastic floor tiles have elongate drainage vents formed to extend from the general upper surfaces of the tiles to general lower surfaces thereof. In a two-shot injection molded embodiment, the vents are laterally spaced from locations of overmolded features, and may be disposed within channels defined by downwardly depending support ribs. In one embodiment, groups of elongate vents are disposed around respective fill points in radiant fashion, so as to minimize the impedance to polymer flow within the injection mold. The vents may be radiussed at the tile's upper surface to enhance their fluid collecting capability.

We claim: 
     
         1 . A modular floor tile injection-molded of at least first and second thermoplastic materials, comprising:
 a body injection-molded from the first thermoplastic material and having a general upper surface and a general lower surface;   a plurality of features overmolded from the second thermoplastic material onto the body, ones of the features being laterally spaced apart from others of the features; and   a plurality of drainage vents formed in the body to extend from the general upper surface to the general lower surface, each drainage vent being laterally spaced from adjacent ones of the features.   
     
     
         2 . The floor tile of  claim 1 , wherein each feature includes at least one pad overmolded on the body to upwardly extend from a plane containing the general upper surface. 
     
     
         3 . The floor tile of  claim 2 , wherein each feature includes a plurality of pads overmolded on the body to upwardly extend from a plane containing the general upper surface, the pads of the feature connected to a common fill point and injection-molded from the second thermoplastic material in a continuous phase. 
     
     
         4 . The floor tile of  claim 2 , wherein at least one crush ring is formed on the body to be disposed upwardly from the general upper surface, said at least one crush ring having a flat surface and laterally surrounding said at least one pad so as to prevent flash of the second thermoplastic material. 
     
     
         5 . The floor tile of  claim 4 , wherein each pad is laterally surrounded by a respective crush ring, each drainage vent being laterally spaced from adjacent ones of the crush rings. 
     
     
         6 . The floor tile of  claim 2 , wherein each feature further includes at least one support member extending below the general lower surface of the body, at least one through-hole formed through the body to communicate said at least one support member to said at least one pad, said at least one paid and said at least one support member injection-molded from a continuous phase of the second thermoplastic material. 
     
     
         7 . The floor tile of  claim 1 , and further comprising a plurality of elongate ribs formed on the body of the first thermoplastic material to downwardly depend from the general lower surface of the body, each feature being laterally surrounded by a respective rib, channels being defined by adjacent ones of the ribs, the drainage vents being disposed in the channels. 
     
     
         8 . The floor tile of  claim 7 , wherein each rib is discontinuous so as to permit flow of drained fluid from a volume laterally interior to the rib to points laterally exterior to the rib. 
     
     
         9 . The floor tile of  claim 1 , wherein each feature includes at least one support member formed of the second thermoplastic material to downwardly extend from the general lower surface of the body. 
     
     
         10 . The floor tile of  claim 9 , wherein each feature includes a group of support members each formed of the second thermoplastic material to downwardly extend from the general lower surface of the body, each group of support members connected to a common fill point. 
     
     
         11 . The floor tile of  claim 9 , and further comprising a crush pad formed in a plane lower than the general lower surface of the body, the crush pad laterally surrounding said at least one support member and providing a flat surface to prevent flash of the second thermoplastic material. 
     
     
         12 . The floor tile of  claim 10 , wherein, for each group of support members, a crush pad is formed on the body to be disposed in a plane lower than the general lower surface of the body, the crush pad laterally surrounding the group of support members, next adjacent ones of the drainage vents being laterally spaced from the crush pads. 
     
     
         13 . The floor tile of  claim 1 , wherein each drainage vent has a surface area in the plane of the general lower surface, a surface area of the drainage vent at the general upper surface being more than 300% of the surface area of the vent taken at the general lower surface. 
     
     
         14 . The floor tile of  claim 1 , wherein the surface area of the vents taken at the general lower surface of the body is no more than about eleven percent of the surface area of the general lower surface of the body. 
     
     
         15 . The floor tile of  claim 14 , wherein said surface area of the vents is about three percent of the surface area of the lower surface of the body. 
     
     
         16 . A modular floor tile injection-molded from a thermoplastic material, comprising:
 a body having a general upper surface and a general lower surface;   a plurality of fill points spaced apart on the body, each fill point associated with a gate of an injection mold used to manufacture the floor tile, the gates introducing molten thermoplastic material into the mold at the fill points, molten polymer spreading from the fill points throughout the mold to define the body; and   a plurality of elongate, spaced-apart drainage vents formed in the body to extend from the general upper surface to the general lower surface, groups of the drainage vents arranged around respective fill points in substantially radiant fashion so as to reduce the impedance of each vent to the flow of molten polymer from the fill points throughout the mold.   
     
     
         17 . The tile of  claim 16 , wherein each vent defines a surface area taken at the general lower surface of the body, a surface area of the last said vent taken at the general upper surface of the body being more than 300% of the surface area of the last said vent taken at the general lower surface of the body. 
     
     
         18 . The tile of  claim 16 , and further comprising a plurality of elongate ribs extending from the general lower surface of the body, the ribs laterally spaced from the vents. 
     
     
         19 . The tile of  claim 16 , and further comprising a plurality of elongate ribs extending from the general lower surface of the body, ones of the ribs laterally intersecting ones of the vents to resist tensile or shear forces experienced across the vent sides. 
     
     
         20 . The tile of  claim 16 , wherein the surface area of the vents taken at the general lower surface of the body is no more than about eleven percent of the surface area of the general lower surface of the body. 
     
     
         21 . A method for manufacturing a modular floor tile, comprising the steps of:
 defining a plurality of gates in a floor tile injection mold to be laterally spaced apart from each other;   defining locations for each of a plurality of elongate vents which extend from a general upper surface of the tile to a general lower surface of the tile, the locations being laterally spaced from the gates;   disposing the vents in groups around respective ones of the gates such that the axes of elongation of the gates are substantially radiant relative to the locations of the gates;   flowing polymer through the gates to fill a volume of the mold; and   responsive to the last said step of disposing, minimizing the impedance to polymer flow caused by the vents.