Fluoropolymer laminates and a process for manufacture thereof
View Patent ↗The present invention provides fluoropolymer laminates having isotropic properties. For example, an embodiment in which multiple fluoropolymer sheets having a 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.
1. A 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 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, the temperature of said extruding being at least the melting point of said LCP and no greater than about 20° C. above said melting point; 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 in different directions; and laminating said multiple sheets together, said laminating being done at a temperature at least equal to the melting point of the fluoropolymer and below the melting point of the LCP.
2. 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 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, the temperature of said extruding being at least the melting point of said LCP and no greater than about 20° C. above said melting point; overlaying at least one sheet obtained from said extruding on at least one side of an 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, said laminating being done at a temperature at least equal to the melting point of the fluoropolymer and below the melting point of the LCP and said polymer sheet having a coefficient of linear expansion of 6×10 −5 /° C. or less.