Polycarbonate-Siloxane Copolymer Use in Baseball and Softball Bats

Abstract

This invention describes the use of a polycarbonate-siloxane block copolymer in the fabrication of various components, especially those subject to repeated impact, for devices such as baseball and softball bats. This material has been shown to possess excellent impact fatigue resistance, a benign mode of failure, and an ability to maintain its shape following impact that was not observed in any other tested polymers.

What is claimed is: 
     
         1 . A device comprising:
 a first barrel section comprising a generally cylindrical hollow body 8-14″ in length and 2-3″ diameter with walls of 0.08-0.25″ thickness developed about a central axis of revolution, a proximal first cylinder end and a distal second cylinder end, wherein the two ends are separated by a mid-section,   a handle section comprising a straight cylindrical body 0.625-1″ diameter, a proximal first end and a distal second end, and a central axis that is collinear with the central axis of the first barrel section,   a transition section comprising a generally conical body revolved about a central axis collinear with the central axes of revolution of the first barrel section and the handle section, the body having a proximal first end sized to be equal in diameter and coplanar to the distal end of the handle and a distal second end sized to be equal in diameter and coplanar to the proximal first cylinder end of the first barrel section,   a knob comprising a short cylindrical body revolved about a central axis collinear with the central axis of the handle with a proximal first end defining the proximal end of the device and a distal second end coplanar with the proximal first end of the handle, and   an endcap comprising a short cylindrical body revolved about a central axis collinear with the central axis of the first barrel section, the body having a proximal first end coplanar with the distal end of the first barrel section and a distal second end defining a distal end of the device   
       wherein at least one of these sections is manufactured using a polycarbonate-siloxane block copolymer. 
     
     
         2 . The device of  claim 1  further comprising a second hollow barrel section comprising a generally cylindrical body disposed concentric to and inside of the first barrel section and having a proximal first end and a distal second end, wherein the two ends are separated by a mid-section, and wherein the outside diameter of the second barrel section is smaller than the inside diameter of the hollow first barrel section and the inside diameter of the second barrel section is larger than the outside diameter of the handle section. 
     
     
         3 . The device of  claim 2  wherein the second barrel section is manufactured using one of a fiberglass composite, a carbon fiber composite, a metal, or a polycarbonate-siloxane block copolymer. 
     
     
         4 . The device of  claim 2  wherein only at least one of the first barrel section and the second barrel section are manufactured using a polycarbonate-siloxane copolymer. 
     
     
         5 . The device of  claim 1  wherein the handle extends beyond the proximal first end of the transition section, through and concentric to one or more of the transition section and the first barrel section. 
     
     
         6 . The device of  claim 1  wherein the siloxane component of the polycarbonate-siloxane block copolymer comprises a molecule within the family of polydimethylsiloxane chemistry. 
     
     
         7 . The device of  claim 1  wherein the polycarbonate component of the polycarbonate-siloxane block copolymer comprises a molecule within the families of bisphenol A polycarbonate or poly-(4,4 isopropyliden diphenyl carbonate). 
     
     
         8 . The device of  claim 1  wherein the molecular weight of the polycarbonate-siloxane block copolymer is in the range of 10,000 to 32,000 Daltons. 
     
     
         9 . The device of  claim 1  wherein the molecular weight of the polycarbonate-siloxane block copolymer is in the range of 24,000 to 32,000 Daltons. 
     
     
         10 . The device of  claim 1  wherein the Melt Flow Index of the polycarbonate-siloxane block copolymer is in the range of 2 to 12 grams per 10 minutes as measured in accordance with ASTM D1238 at a temperature of 300° C. and a load of 2.65 pounds. 
     
     
         11 . The device of  claim 1  wherein the Melt Flow Index of the polycarbonate-siloxane block copolymer is in the range of 2 to 6 grams per 10 minutes as measured in accordance with ASTM D1238 at a temperature of 300° C. and a load of 2.65 pounds. 
     
     
         12 . The device of  claim 1  wherein the tensile modulus of the polycarbonate-siloxane block copolymer is about 320,000 psi as measured in accordance with ASTM D638 at a loading rate of 50 mm/min. 
     
     
         13 . The device of  claim 1  wherein the tensile yield of the polycarbonate-siloxane block copolymer is about 8700 psi as measured in accordance with ASTM D638, Type I, at a loading rate of 50 mm/min. 
     
     
         14 . The device of  claim 1  wherein a 0.1″ thick section of the molded polycarbonate-siloxane block copolymer has a visible light transmission rate of at least 80% in accordance with ASTM D1003. 
     
     
         15 . The device of  claim 14  wherein product graphics are disposed on the inside surface of the first barrel section. 
     
     
         16 . The device of  claim 14  wherein the device further comprising a second hollow barrel section comprising a generally cylindrical body disposed concentric to and inside of the first barrel section and having a proximal first end and a distal second end, wherein the two ends are separated by a mid-section, and wherein the outside diameter of the second barrel section is smaller than the inside diameter of the hollow first barrel section and the inside diameter of the second barrel section is larger than the outside diameter of the handle section and wherein product graphics are disposed on the outside surface of the second barrel section. 
     
     
         17 . The device of  claim 1  wherein a 0.1″ thick section of the molded polycarbonate-siloxane block copolymer has a visible light transmission rate of less than 20% in accordance with ASTM D1003. 
     
     
         18 . The device of  claim 1  wherein a 0.1″ thick section of the molded polycarbonate-siloxane block copolymer has a haze value for visible light transmission rate of less than 5% in accordance with ASTM D1003. 
     
     
         19 . The device of  claim 1  wherein the mid-section of the first barrel section is larger in diameter than the proximal first cylinder end or the distal second cylinder end.