Puncture resistant flexible metatarsal guard

Abstract

A metatarsal guard includes a base layer, an elastomeric polyurethane foam layer on the base layer, and a puncture resistant layer on the elastomer foam layer on a side opposite the base layer. Advantageously, the metatarsal guard is flexible and capable of providing top-of-foot protection to the metatarsal region of a foot. The metatarsal guard is formed by a molding process. A safety shoe or boot having improved protection for the metatarsal region of a wearer's foot is also disclosed.

1 . A metatarsal guard comprising:
 a base layer;   an elastomeric polyurethane foam layer on the base layer; and   a puncture resistant layer on the elastomer foam layer on a side opposite the base layer;   wherein the metatarsal guard is flexible.   
     
     
         2 . The metatarsal guard of  claim 1 , wherein the base layer comprises a thermoplastic polyurethane. 
     
     
         3 . The metatarsal guard of  claim 1 , wherein the elastomeric polyurethane foam layer is an open cell polyurethane foam. 
     
     
         4 . The metatarsal guard of  claim 1 , wherein the elastomeric polyurethane foam has an average cell size of 50 to 250 micrometers. 
     
     
         5 . The metatarsal guard of  claim 1 , wherein the elastomeric polyurethane foam has a density of 5 to 30 pcf (0.08 to 0.48 g/cm 3 ). 
     
     
         6 . The metatarsal guard of  claim 1 , wherein the elastomeric polyurethane foam has a compression set at 70° F. of less than 10% as determined in accordance with ASTM-D 3574 Test D and a 25% compression force deflection of 1 to 9 psi as determined by ASTM-D 3574: PTP-0033 at 25% deflection. 
     
     
         7 . The metatarsal guard of  claim 1 , wherein the elastomeric polyurethane foam is unfilled. 
     
     
         8 . The metatarsal guard of  claim 1 , wherein the puncture resistant layer comprises a woven polyester fabric or a woven polyamide fabric. 
     
     
         9 . The metatarsal guard of  claim 1 , wherein the puncture resistant layer comprises a woven polyester fabric. 
     
     
         10 . The metatarsal guard of claim  10 , wherein the woven polyester fabric has a weight of 750 to 800 g/m 2 . 
     
     
         11 . The metatarsal guard of  claim 1 , wherein the puncture resistant layer has a thickness of 0.1 to 2 millimeters. 
     
     
         12 . The metatarsal guard of  claim 1 , wherein the puncture resistant layer comprises a woven polyester fabric having
 a weight of 750 to 800 g/m 2 ;   a thickness of 0.65 to 1.25 millimeters; and   a level 3 puncture resistance according to EN388:6.5-16.   
     
     
         13 . The metatarsal guard of  claim 1 , wherein the metatarsal guard has a thickness of 1 to 20 millimeters (mm). 
     
     
         14 . The metatarsal guard of  claim 1 , wherein the metatarsal guard is formed by a method comprising:
 arranging in a mold
 the base layer; 
 the elastomeric polyurethane foam layer on the base layer; and 
 the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and 
   applying heat and pressure to the mold to provide the metatarsal guard.   
     
     
         15 . The metatarsal guard of  claim 1 , comprising:
 the base layer, comprising a thermoplastic polyurethane;   the elastomeric polyurethane foam layer, wherein
 the elastomeric polyurethane foam layer is an open cell polyurethane foam, 
 the elastomeric polyurethane foam has an average cell size of 50 to 250 micrometers, and 
 the elastomeric polyurethane foam has a density of 5 to 30 pcf.; and 
   the puncture resistant layer, comprising a woven polyester fabric having
 a weight of 750 to 800 g/m 2 , 
 a thickness of 0.65 to 1.25 millimeters, and 
 a level 3 puncture resistance according to EN388:6.5-16; 
   wherein the metatarsal guard is flexible; and   wherein the metatarsal guard has a total thickness of 5 to 7 millimeters or 11 to 14 mm.   
     
     
         16 . The metatarsal guard of  claim 1 , wherein a force required for a dart having a tip diameter of 1 millimeter moving at a speed of 100 mm/min to puncture the metatarsal guard is at least 100% greater than a force required to puncture a comparative metatarsal guard not including the puncture resistant layer. 
     
     
         17 . A method for the manufacture of a metatarsal guard of  claim 1 , the method comprising:
 arranging in a mold
 the base layer; 
 the elastomeric polyurethane foam layer on the base layer; and 
 the puncture resistant layer on the elastomer foam layer on a side opposite the base layer; and 
   applying heat and pressure to the mold to provide the metatarsal guard.   
     
     
         18 . A safety shoe or boot having improved protection for the metatarsal region of a wearer's foot, the safety shoe or boot comprising the metatarsal guard of  claim 1 . 
     
     
         19 . The safety shoe or boot of  claim 18 , comprising:
 a sole;   an upper portion having an interior surface, the upper portion being affixed to the sole wherein the upper portion and the sole define a cavity for receiving a wearer's foot;   a rigid toe protector affixed between the upper portion and the sole; and   the metatarsal guard positioned inside the upper portion and adjacent to the rigid toe protector to cover a top side of the metatarsal region of the wearer's foot.   
     
     
         20 . A method for providing top-of-foot protection to the metatarsal region of a foot, the method comprising:
 affixing a metatarsal guard inside an upper portion of a safety shoe or boot, the metatarsal guard comprising:   a base layer;   an elastomeric polyurethane foam layer on the base layer; and   a puncture resistant layer on the elastomer foam layer on a side opposite the base layer;   wherein the metatarsal guard is flexible.