Method of manufacturing a foam mat

Abstract

A method of manufacturing a substantially flat foam floor mat is described. The raw materials for each color layer are separately mixed and heated below their foaming temperature in different batches, and separately pressed through heated rollers to form a plurality of unfoamed sheets. The temperature of the rollers are maintained within a range of 5° C. or less. Two or more unfoamed sheets from each batch are stacked together in a press and heated above their foaming temperature to permit the stacked sheets to foam, expand, and heat-weld together. 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 are cut around the boundary of the mat to form an interlocking peripheral wall.

1 . A method of forming a substantially flat foam floor mat, comprising:
 forming a stack of (i) at least first and second sheets of a first color, and (ii) at least third and fourth sheets of a second color;   heating and pressing the stack such that the first sheet foams and heat welds to the second sheet, the second sheet foams and heat welds to the third sheet, and the third sheet foams and heat welds to the fourth sheet; and   trimming the heated and pressed stack to form a boundary of interlocking teeth.   
     
     
         2 . The method of  claim 1 , wherein the stack has no more than six sheets total. 
     
     
         3 . The method of  claim 1 , wherein the stack comprises (i) three sheets of the first color, inclusive of the first and second sheets, and (ii) three sheets of the second color, inclusive of the third and fourth sheets. 
     
     
         4 . The method of  claim 1 , wherein the step of forming a stack of (i) at least first and second sheets of a first color, and (ii) at least third and fourth sheets of a second color comprises:
 compounding together a blend of raw ingredients;   heating the blend of raw ingredients together to a first temperature that is below a polymer foaming temperature;   pressing the blend of raw ingredients through a pair of rollers and into sheets.   
     
     
         5 . The method of  claim 4 , wherein the step of heating and pressing the stack comprises heating the stack above the polymer foaming temperature. 
     
     
         6 . The method of  claim 4 , further comprising the step of maintaining the temperature of each roller within a range of five degrees Celsius when pressing the blend of raw ingredients into sheets. 
     
     
         7 . The method of  claim 4 , wherein the sheets have a uniform thickness. 
     
     
         8 . The method of  claim 1 , wherein the step of heating and pressing the stack comprises placing the stack between a tray and a top plate to restrict vertical expansion of the stack while horizontal expansion is unrestricted. 
     
     
         9 . The method of  claim 8 , wherein the bottom tray has a first die that imparts a first texture to a bottom surface of the mat and the top plate has a second die that imparts a second texture to a top surface of the mat.