US2002142689A1PendingUtilityA1

Non-woven sheet of aramid floc

45
Priority: Jan 23, 2001Filed: Jan 23, 2001Published: Oct 3, 2002
Est. expiryJan 23, 2021(expired)· nominal 20-yr term from priority
Inventors:Mikhail R. Levit
C08J 5/04H05K 1/0366D21H 25/04D21H 25/005D21H 13/26Y10T442/689Y10T442/69Y10T442/692Y10T442/697Y10T442/659Y10T428/23943D04H 1/00
45
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Claims

Abstract

The present invention relates to a wet-laid non-woven sheet made from a essentially binder-free aramid floc, wherein the aramid floc includes at least 25 percent by weight of para-aramid floc based on the total weight of aramid floc only, and a process for making the sheet.

Claims

exact text as granted — not AI-modified
What is claimed is:  
     
         1 . A wet-laid non-woven sheet comprising essentially binder-free aramid floc, wherein the aramid floc includes at least 25 percent by weight of para-aramid floc based on the total weight of aramid floc only.  
     
     
         2 . The wet-laid non-woven sheet of  claim 1 , wherein the aramid floc includes at least 50 percent by weight of para-aramid floc based on the total weight of aramid floc only.  
     
     
         3 . The wet-laid non-woven sheet of  claim 1 , wherein the aramid floc includes at least 75 percent by weight of para-aramid floc based on the total weight of aramid floc only.  
     
     
         4 . The wet-laid non-woven sheet of  claim 1 , wherein the aramid floc includes 100 percent by weight of para-aramid floc based on the total weight of aramid floc only.  
     
     
         5 . The wet-laid non-woven sheet of  claim 1 , wherein the aramid floc has an average length of from 3 to 13 millimeters  
     
     
         6 . The wet-laid non-woven sheet of  claim 1 , wherein the floc has been hydroentangled.  
     
     
         7 . The wet-laid non-woven sheet of  claim 1 , which has been hot calendered.  
     
     
         8 . The wet-laid non-woven sheet of  claim 6 , which has been hot calendered.  
     
     
         9 . The wet-laid non-woven sheet of  claim 1 , wherein the aramid floc comprises para-aramid floc and meta-aramid floc.  
     
     
         10 . A prepreg that includes the wet-laid non-woven sheet of  claim 1 .  
     
     
         11 . A prepreg that includes the wet-laid non-woven sheet of  claim 7 .  
     
     
         12 . A prepreg that includes the wet-laid non-woven sheet of  claim 8 .  
     
     
         13 . A laminate made from the prepreg of  claim 10 .  
     
     
         14 . A laminate made from the prepreg of  claim 11 .  
     
     
         15 . A laminate made from the prepreg of  claim 12 .  
     
     
         16 . A printed wiring board that includes the laminate of  claim 13 .  
     
     
         17 . A printed wiring board that includes the laminate of  claim 14 .  
     
     
         18 . A printed wiring board that includes the laminate of  claim 15 .  
     
     
         19 . A process for making a sheet of essentially binder-free aramid floc, wherein the aramid floc includes at least 25 percent by weight of para-aramid floc based on the total weight of aramid floc only, comprising the steps of: 
 a) preparing an aqueous dispersion of 0.005 to 0.08 weight percent of essentially binder-free aramid floc that includes at least 25 percent by weight of para-aramid floc;    b) pouring the dispersion onto a moving screen in a paper making machine;    c) withdrawing water from the aqueous dispersion to leave a wet paper felt; and    d) drying the wet paper felt on the supporting screen to make a sheet of essentially binder-free aramid floc.    
     
     
         20 . The process of  claim 19  wherein the aramid floc has an average length of from 3 to 13 millimeters.  
     
     
         21 . The process of  claim 19  further comprising the step of hydroentangling the non-woven sheet before or after the non-woven sheet is dried.  
     
     
         22 . The process of  claim 19  further comprising the step of hot calendering the dried sheet of essentially binder-free aramid floc.  
     
     
         23 . The process of  claim 21  further comprising the step of hot calendering the dried sheet of essentially binder-free aramid floc.  
     
     
         24 . The process of  claim 19 , wherein the aramid floc comprises para-aramid floc and meta-aramid floc.  
     
     
         25 . The process of  claim 19  further comprising the step of impregnating the sheet of essentially binder-free aramid floc with a resin to form a prepreg.

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