Plastic toe cap and method of making

Abstract

A toe cap is a reinforcement member made of thermoset structural composite material with a tensile strength of 30,000 psi, a tensile modulus of 2.5×10 6 psi, a compression strength of 35,800 psi, a specific gravity of 1.85, and a Barcol hardness of 65. More preferably, the material has a tensile strength of at least 50,000 psi, a tensile modulus of at least 3.8×10 6 psi, a compression strength of at least 42,000 psi, a specific gravity of at least 1.90, and a Barcol hardness of at least 70. A suitable family of materials is a thermoset vinyl ester based sheet molding compound reinforced with glass fiber and/or carbon fiber. The sheet molding compound has fiber content of about 63% and a typical fiber length of one inch. The maximum wall thickness of the upper portion of the toe cap is in the range of between 0.100 inch and 0.250 inch.

I claim:  
     
         1 . A toe cap for reinforcement of shoes, boots and the like, comprising: 
 a reinforcement member having a generally C-shaped cross section, said reinforcement member being made of thermoset structural composite material with a tensile strength of at least 30,000 psi, a tensile modulus of at least 2.5×10 6  psi, a specific gravity of at least 1.85, and a Barcol hardness of at least 65.    
     
     
         2 . The toe cap of  claim 1  wherein said material has a compression strength of at least 35,800 psi.  
     
     
         3 . The toe cap of  claim 1  wherein said reinforcement member has a tensile strength of at least 50,000 psi, a tensile modulus of at least 3.8×10 6  psi, a specific gravity of at least 1.90 and a Barcol hardness of at least 70.  
     
     
         4 . The toe cap of  claim 3  wherein said material has a compression strength of at least 42,000 psi.  
     
     
         5 . The toe cap of  claim 1  wherein said generally C-shaped reinforcement member comprises 
 a) an upper portion including a top surface and a generally vertical wall portion and,  
 b) a substantially horizontal base.  
 
     
     
         6 . The toe cap of  claim 5  wherein said generally vertical wall portion is interconnected to said substantially horizontal base by a chamfer.  
     
     
         7 . The toe cap of  claim 6  wherein said chamfer forms an angle with said base in a range of between 120° and 150°.  
     
     
         8 . The toe cap of  claim 7  wherein said chamfer forms an angle of generally 135° with said base.  
     
     
         9 . The toe cap of  claim 5  wherein said upper portion has a maximum thickness which falls in the range of between 0.100 inch and 0.250 inch.  
     
     
         10 . The toe cap of  claim 9  wherein said upper portion has a thickened region across an instep which is as much as 0.050 inch thicker than other portions of said toe cap.  
     
     
         11 . The toe cap of  claim 1  wherein said toe cap is made of a fiber reinforced, vinyl ester based sheet molding compound.  
     
     
         12 . A process of making a toe cap comprising the steps of 
 a. cutting a swatch of fiber reinforced, vinyl ester based sheet molding compound to a predetermined size;    b. inserting said swatch in a shaping mold having a male and female member which between them, define a desired shape of said toe cap;    c. compressing said swatch to a pressure between 200 psi and 1000 psi in said shaping mold producing a maximum thickness in an upper portion of said toe cap which falls in the range of between 0.100 inch and 0.250 inch;    d. curing said swatch at a temperature between 240° and 320° F. for a period of between 1 and 4 minutes;    e. ejecting said toe cap from said shaping mold.    
     
     
         13 . The process of  claim 12  wherein said cutting step comprises cutting a swatch with a predetermined size which is greater than twice the size of said toe cap and said inserting step involves inserting said swatch into a double wide mold capable of simultaneously shaping a left toe cap and a right toe cap.  
     
     
         14 . The process of  claim 13  further comprising the step of cutting said left and right toe caps loose from an interconnecting membrane.  
     
     
         15 . A process of making a pair of toe caps with a predetermined finished size comprising the steps of 
 a. cutting a swatch of fiber reinforced, vinyl ester based molding compound to a predetermined size which is more than twice said predetermined finished size;    b. inserting said swatch in a shaping mold having a male and female member which between them, define desired shapes of both a right toe cap and a left toe cap;    c. compressing said swatch to a pressure between 200 psi and 1000 psi in said shaping mold;    d. curing said swatch at a temperature between 240° and 320° F. for a period of between 3 and 5 minutes;    e. ejecting said toe cap from said shaping mold;    f. cutting said right and left toe caps loose by removing an interconnecting membrane.