Liquid crystal polymer film

A method of preparing a multiaxially oriented film from high molecular weight liquid crystalline lyotropic or thermotropic polymers comprising the steps of:

• (a) subjecting axially flowing liquid crystalline polymer material to transverse-directional motions, thereby straining the axial flow;
• and
• (b) solidifying the microscale structural orientation formed in step (a), wherein said film is formed by first forming two individual intermediate-product films each having a substantially biaxial orientation, and then laminating said intermediate films in a continuous process to form said film having planar surface regions defined by positive molecular orientation angle and an inner region define negative molecular orientation angle, with respect to the longitudinal axis.

A multiaxially oriented liquid crystalline film exhibiting a nearly uniform coefficient of thermal expansion in all planar directions prepared from high molecular weight liquid crystalline lyotropic or thermotropic polymers, having a controlled molecular orientation in substantially any plane of said film, which orientation in each plane is defined by a selected positive or negative angle with respect to a longitudinal axis of said film, said film having two surface layers, one said surface layer having a positive angle defined by said molecular orientation, the orientation of the other surface layer being negative, and said film having a central core layer wherein said orientation is generally along said longitudinal axis, wherein said layers are respective portions of an integral film structure formed by a single die-forming process, and wherein said film is formed by employing a tubular die having at least three concentric mandrels including outer, inner, and middle mandrels which form two annular flow channels therebetween, and a third annular flow channel, within said middle mandrel;

• supplying the polymer through said channels;
• rotating at least the outer and inner mandrels;
• and joining the respective polymer films formed in said channels to form said film.

A multiaxially oriented liquid crystal polymer film structure from high molecular weight liquid crystalline lyotropic or thermotropic polymers comprising two outer surface layers which are oriented generally in a first controllable direction;

• two intermediate layers respectively inward of said outer surface layers which are oriented generally in a second controllable direction;
• and a central core layer sandwiched between said intermediate layers which is oriented generally in a third controllable direction, said film having a nearly uniform coefficient of thermal expansion in all planar directions.