Fluoropolymer laminates and a process for manufacture thereof

Abstract

The present invention provides fluoropolymer laminates having isotropic properties. For example, an embodiment in which multiple fluoropolymer sheets having an liquid crystalline polymer oriented in the fibrous state in the melt processible fluoropolymer are laminated, despite having the fibrous LCP oriented in one direction in each single extruded sheet, makes it possible to laminate in such a way as to compensate for their orientation directions, the laminate thereby becoming isotropic as regards physical properties. The laminates also have low linear coefficient of expansion and low thermal shrinkage as well as elevated tensile modulus and low dielectric constant.

What is claimed is:  
     
         1 . Fluoropolymer laminate comprising melt processible fluoropolymer layers wherein at least one layer thereof is a fluoropolymer sheet layer in which an LCP is oriented in the fibrous state in the melt processible fluoropolymer.  
     
     
         2 . The laminate as set forth in  claim 1 , wherein said laminate comprises at least two fluoropolymer sheet layers having an LCP oriented in the fibrous state in the melt processible fluoropolymer, and wherein at least two layers thereof have fibrous LCP whose orientation is in directions different from each other.  
     
     
         3 . The laminate as set forth in  claim 1 , wherein the fluoropolymer sheet layer having an LCP oriented in the fibrous state in the melt processible fluoropolymer is a fibrous sheet layer selected from a woven fabric, a non-woven fabric, and a knitted fabric of melt processible fluoropolymer fibers containing the LCP oriented in the fibrous state.  
     
     
         4 . The laminate as set forth in  claim 1 , wherein the fluoropolymer sheet layer having an LCP oriented in the fibrous state in the melt processible fluoropolymer contains the LCP in a range of about 3-30% by weight thereof.  
     
     
         5 . The laminate as set forth in  claim 1 , wherein at least one of said layers is a melt processible fluoropolymer sheet containing no fibrous LCP laminated to at least one side of said at least one fluoropolymer sheet layer in which the LCP is oriented in the fibrous state.  
     
     
         6 . The laminate as set forth in  claim 1 , wherein at least part of the melt processible fluoropolymer is a functional-group-containing fluoropolymer.  
     
     
         7 . The laminate as set forth in  claim 1 , wherein at least one of said layers is a polymer layer with a coefficient of linear expansion of about 6×10 −5 /° C. or less laminated to at least one side of said at least one fluoropolymer sheet layer in which the LCP is oriented in the fibrous state.  
     
     
         8 . The laminate as set forth in  claim 7 , wherein the fluoropolymer sheet layer in which an LCP is oriented in the fibrous state in the melt processible fluoropolymer is laminated to at least one side of the polymer layer with a coefficient of linear expansion of about 3×10 −5 /° C. or less.  
     
     
         9 . The laminate as set forth in  claim 1 , and additionally copper cladding on one or both sides of said laminate.  
     
     
         10 . The laminate as set forth in  claim 7 , wherein said fluoropolymer sheet layer in which an LCP is oriented in the fibrous state in a melt processible fluoropolymer is laminated to both sides of said polymer layer with a coefficient of linear expansion of about 6×10 −5 /° C. or less, and wherein the orientation direction of the fibrous LCP in each said fluoropolymer sheet layers is the same or different.  
     
     
         11 . The laminate as set forth in  claim 1 , wherein said laminate has a thermal shrinkage at 250° C. of not more than about 1.5% and a dielectric constant at a frequency of 1 GHz of not more than about 3.0.  
     
     
         12 . A process for the manufacture of fluoropolymer laminate, comprising melt mixing a melt processible fluoropolymer with an LCP having a melting point of at least about 15° C. higher than that of said melt processible fluoropolymer; extruding the resultant melt mixture in the form of a sheet in which the LCP is oriented in the fibrous state in the melt processible fluoropolymer in the direction of said extruding; overlaying multiple sheets obtained from said extruding in such a way that at least two sheets will have their respective LCP oriented in the fibrous state oriented indifferent directions; and laminating said multiple sheets together.  
     
     
         13 . The process for the manufacture of fluoropolymer laminate, comprising overlaying a melt processible fluoropolymer sheet containing no fibrous LCP on at least one side of a fibrous sheet selected from a woven fabric, a non-woven fabric, or a knitted fabric of fluoropolymer fibers having an LCP oriented in the fibrous state in the melt processible fluoropolymer in the fiber direction; and laminating said fluoropolymer sheet and said fibrous sheet together.  
     
     
         14 . The process for the manufacture of a fluoropolymer laminate, comprising melt mixing a melt processible fluoropolymer with an LCP having a melting point of at least about 15° C. higher than that of said melt processible fluoropolymer; extruding the resultant melt mixture into the formation of a sheet in which the LCP is oriented in the fibrous state in the melt processible fluoropolymer in the direction of said extruding; overlaying at least one sheet obtained from said extruding on at least one side of a isotropic polymer sheet with a coefficient of linear expansion of about 6×10 −5 /° C. or less; and laminating said fluoropolymer sheet and said polymer sheet together.