Prepreg tape slitting method and apparatus

Abstract

Improved methods and apparatus are provided for the production of prepreg slit tape wherein master rolls of prepreg sheet are formed which are capable of being slit, with liner attached, at high precision.

I claim: 
     
         1 . A method for the production of slit tape from a master roll of a continuous sheet of prepreg material comprising:
 a) unwinding the master roll of prepreg material;   b) feeding the continuous sheet of prepreg material with a liner overlaying and attached to at least one surface of the continuous sheet into and through a slitter, thereby simultaneously slitting the prepreg sheet and liner, and   c) winding the so formed slit tape, with liner attached;   
       wherein the liner is a polymer film which is 1) able to be slit by the slitter without tearing, without the formation of fibrils, and without separating from the prepreg material; 2) resists elongation and/or the creation of stress fractures in the film under the stress of winding, and c) manifests a sufficient adhesive or peel strength with the prepreg material so as avoid separating from the prepreg material under the stresses of the unwinding, slitting and winding processes. 
     
     
         2 . The method of  claim 1  where in the master roll comprises the prepreg sheet material with the liner attached. 
     
     
         3 . The method of  claim 1  wherein the master roll comprises the prepreg sheet material with a paper or polymer film backing attached and the method further comprises the step of removing the backing and replacing the backing with the liner while it is being unwound from the master roll and prior to being fed to the slitter. 
     
     
         4 . The method of  claim 1  wherein the liner is composed of a material that is compatible with the matrix resin of the prepreg material. 
     
     
         5 . The method of  claim 1  wherein the liner is composed of a material that has a thickness of 0.1 to about 12 mils, a lengthwise tensile strength of 500 psi to 40,000 psi, and an arithmetic average surface roughness of 0.01 to 200 um. 
     
     
         6 . The method of  claim 1  wherein the polymer film liner is composed of a polyolefin, a polyamide, a polyester, a vinyl polymer, or a polyacetate. 
     
     
         7 . The method of  claim 1  wherein the polymer film liner is polyethylene. 
     
     
         8 . A method of preparing a continuous sheet of prepreg material suitable for use in the practice of the method of  claim 1  wherein the method comprises:
 a) unwinding a master roll of a continuous sheet of prepreg material having a paper or polymer film backing attached, 
 b) removing the backing from the prepreg material, 
 c) aligning and mating a polymer film liner with the prepreg material, and 
 d) rewinding the mated prepreg material and polymer film liner to form a new master roll; 
 
       wherein the liner is a polymer film which is 1) able to be slit by the slitter without tearing, without the formation of fibrils, and without separating from the prepreg material; 2) resists elongation and/or the creation of stress fractures in the film under the stress of winding, and c) manifests a sufficient adhesive or peel strength with the prepreg material so as avoid separating from the prepreg material under the stresses of the unwinding, slitting and winding processes. 
     
     
         9 . The method of  claim 8  wherein the liner is composed of a material that is compatible with the matrix resin of the prepreg material. 
     
     
         10 . The method of  claim 8  wherein the liner is composed of a material that has a thickness of 0.1 to about 12 mils, a lengthwise tensile strength of 500 psi to 40,000 psi, and an arithmetic average surface roughness of 0.01 to 200 um. 
     
     
         11 . The method of  claim 8  wherein the polymer film liner is composed of a polyolefin, a polyamide, a polyester, a vinyl polymer, or a polyacetate. 
     
     
         12 . The method of  claim 8  wherein the polymer film liner is polyethylene. 
     
     
         13 . A master roll of a continuous sheet of prepreg material, said master roll having been formed by a method comprising:
 a) unwinding a master roll of a continuous sheet of prepreg material having a paper or polymer film backing attached,   b) removing the backing from the prepreg material,   c) aligning and mating a polymer film liner with the prepreg material, and   d) rewinding the mated prepreg material and polymer film liner to form a new master roll;   
       wherein the liner is a polymer film which is 1) able to be slit by the slitter without tearing, without the formation of fibrils, and without separating from the prepreg material; 2) resists elongation and/or the creation of stress fractures in the film under the stress of winding, and c) manifests a sufficient adhesive or peel strength with the prepreg material so as avoid separating from the prepreg material under the stresses of the unwinding, slitting and winding processes. 
     
     
         14 . The method of  claim 13  wherein the liner is composed of a material that is compatible with the matrix resin of the prepreg material. 
     
     
         15 . The method of  claim 13  wherein the liner is composed of a material that has a thickness of 0.1 to about 12 mils, a lengthwise tensile strength of 500 psi to 40,000 psi, and an arithmetic average surface roughness of 0.01 to 200 um. 
     
     
         16 . The method of  claim 13  wherein the polymer film liner is composed of a polyolefin, a polyimide, a polyester, a vinyl polymer, or a polyacetate. 
     
     
         17 . The method of  claim 13  wherein the polymer film liner is polyethylene. 
     
     
         18 . An apparatus for the conversion of master rolls of continuous sheets of prepreg materials having a paper or polymer film backing to a master roll of a prepreg material having a liner whereby the prepreg material may be slit with liner attached, said apparatus comprising a master roll station for holding and unwinding the original master roll, a separator station wherein the backing of the original master roll is removed from the prepreg sheet material, a lining station wherein the prepreg material is aligned with an mated to a polymer film liner, and a winding station wherein the prepreg and liner are wound into a new master roll. 
     
     
         19 . The apparatus of  claim 18  wherein the master roll station comprises an axel, which may be motorized, upon which the master roll of prepreg material is to be mounted; the separator station comprises a motorized axel upon which a spindle is to be mounted for taking up and winding the backing as it is removed from the prepreg sheet material; the lining station comprises an axel, which may be motorized, upon which a roll of liner material is to be placed, and alignment mean for aligning and mating the liner material with the prepreg material; and the winding station comprises a motorized axel upon which a spindle is to be mounted about which the prepreg and liner combination is to be wound. 
     
     
         20 . An improved process for the production of master rolls of continuous sheets of prepreg material adapted wherein the improvement comprises using a polymer film liner material as the backing in the preparation of the prepreg sheet wherein the liner is 1) able to be slit by the slitter without tearing, without the formation of fibrils, and without separating from the prepreg material; 2) resists elongation and/or the creation of stress fractures in the film under the stress of winding, and c) manifests a sufficient adhesive or peel strength with the prepreg material so as avoid separating from the prepreg material under the stresses of the unwinding, slitting and winding processes. 
     
     
         21 . An improved process for the production of slit tape wherein the improvement comprises the feeding a prepreg sheet material having a liner attached thereto directly into and through the slitter wherein the liner is 1) able to be slit by the slitter without tearing, without the formation of fibrils, and without separating from the prepreg material; 2) resists elongation and/or the creation of stress fractures in the film under the stress of winding, and c) manifests a sufficient adhesive or peel strength with the prepreg material so as avoid separating from the prepreg material under the stresses of the unwinding, slitting and winding processes: said improved process eliminating the need to remove the backing from the prepreg material as it is being fed to the slitter and the need to insert a liner between successive windings of the slit tape as it is being wound. 
     
     
         22 . The improved process of  claim 21  wherein the improvement is integrated into a continuous process for the production of slit tape, said continuous process comprising the formation of the prepreg sheet material, the slitting of the so formed prepreg sheet material and the winding of the subsequently formed slit tape.