Foam mat

Abstract

A two layer foam mat is described. The raw materials for each layer are separately mixed and heated in different batches, and separately pressed through heated rollers to form a plurality of sheets. One or more sheets from each batch are stacked together in a press and heated above a foaming temperature to permit the stacked sheets to foam and expand. The press restricts the sheets from vertical expansion while allowing horizontal expansion. Once the sheets are foamed, a series of alternating teeth and receiving slots can be cut around the boundary of the mat to form an interlocking peripheral wall. The layers preferably have the same chemical composition after foaming, even though the layers are formed from different batches and may have different colors and/or textures.

1 . A foam mat comprising a body bounded by an interlocking peripheral wall, the body comprising:
 a first layer made from a first batch of raw materials comprising a first polymer and a second polymer;   a second layer made from a second batch of raw materials comprising the first polymer and the second polymer;   wherein the first layer and second layer are made by (i) separately heating and mixing the first batch of raw materials and the second batch at a temperature that is below a foaming temperature of the first batch of raw materials and the second batch of raw materials, respectively; (ii) separately heating and pressing the first batch of raw materials and the second batch of raw materials through rollers that are maintained within uniform temperatures of a range of 5° C. to form a first plurality of sheets and a second plurality of sheets, respectively; and (iii) stacking, pressing, and heating one or more of the first plurality of sheets and one or more of the second plurality of sheets to a temperature that permits the sheets to foam and expand; and   wherein, after foaming and expansion, the first layer comprises a first chemical composition and the second layer comprises a second chemical composition that is substantially similar to the first chemical composition so that the first layer and second layer respond similarly when subject to temperature changes and forces.   
     
     
         2 . The foam mat of  claim 1  wherein the first polymer comprises ethylene vinyl acetate (EVA) and the second polymer comprises polyethylene (PE). 
     
     
         3 . The foam mat of  claim 2  wherein the EVA is recycled EVA, and the PE is virgin PE. 
     
     
         4 . The foam mat of  claim 2  wherein the EVA is virgin EVA, and the PE is recycled PE. 
     
     
         5 . The foam mat of  claim 2  wherein the EVA is virgin EVA, and the PE is virgin PE. 
     
     
         6 . The foam mat of  claim 1  wherein the second batch of raw materials comprising the same amount of the first polymer and the second polymer as the first batch of raw materials. 
     
     
         7 . The foam mat of  claim 1  wherein the first layer and the second layer have the same coefficient of thermal expansion and the same elastomeric properties. 
     
     
         8 . The foam mat of  claim 1 , wherein the first batch of raw materials comprises a first colorant and the second batch of raw materials comprises a second colorant that is different that the first colorant. 
     
     
         9 . The foam mat of  claim 1 , wherein the first layer comprises a first texture and the second layer comprises a second texture that is different than the first texture. 
     
     
         10 . The foam mat of  claim 1  wherein the interlocking peripheral wall comprises a plurality of alternating teeth and receiving slots. 
     
     
         11 . A method of manufacturing a foam mat comprising a first layer and a second layer, the method comprising the steps of:
 (i) separately heating and mixing a first batch of raw materials and a second batch of raw materials at a temperature that is below a foaming temperature of the first batch of raw materials and the second batch of raw materials, respectively;
 wherein the first batch of raw materials comprises a first polymer, a second polymer, and a colorant; and 
 wherein the second batch of raw materials comprises the first polymer, the second polymer, and a second colorant; 
   (ii) separately heating and pressing the first batch of raw materials and the second batch of raw materials through rollers that are maintained within uniform temperatures of a range of 5° C. to form a first plurality of sheets and a second plurality of sheets, respectively; and   (iii) stacking, pressing, and heating one or more of the first plurality of sheets and one or more of the second plurality of sheets to a temperature that permits the sheets to foam and expand; and   (iv) cutting a plurality of alternating teeth and receiving slots around a peripheral wall of the mat.   
     
     
         12 . The method of  claim 11  wherein the first polymer has a first rate of foaming and the second polymer has a second rate of foaming that is different than the first rate of foaming. 
     
     
         13 . The method of  claim 11  wherein the first polymer has a first rate of expansion and the second polymer has a second rate of expansion that is different than the first rate of expansion. 
     
     
         14 . The method of  claim 11  wherein the step of stacking, pressing, and heating one or more of the first plurality of sheets and one or more of the second plurality of sheets comprises stacking the sheets in a press. 
     
     
         15 . The method of  claim 14  wherein the press comprises a top plate and a bottom tray. 
     
     
         16 . The method of  claim 15  wherein the bottom tray comprises a first die having a first texture. 
     
     
         17 . The method of  claim 16  wherein the top place comprises a second die having a second texture that is different than the first texture. 
     
     
         18 . The method of  claim 11  wherein the step of stacking, pressing, and heating one or more of the first plurality of sheets and one or more of the second plurality of sheets comprises stacking three or more of the first plurality of sheets and three or more of the second plurality of sheets. 
     
     
         19 . The method of  claim 11  wherein the first plurality of sheets and the second plurality of sheets have a uniform thickness. 
     
     
         20 . The method of  claim 11  wherein the first plurality of sheets and the second plurality of sheets have a thickness between 5 to 10 millimeters.