Methods of manufacturing sequentially stretched polymer films, apparatus used for such methods, and products obtained thereby

A process of orienting a film or assembly of films comprising:

• feeding the film or the assembly between rubber belts which engage the film or the assembly so that while the film or the assembly contracts from a longitudinally strained state to a less strained state, the film or assembly obtains a fine traverse waving,
• stuffing the film or the assembly into a nip between two circularly or helically mutually intermeshing grooved rollers, grooved roller (101) and grooved roller (102), where the film or the assembly obtains a fine traverse waving either prior to or while entering the nip to form a waved film or a waved film assembly, and
• sequentially stretching the waved film or the waved assembly substantially in a transverse direction upon passing through the nip to form first row formed segments interspersed with second row formed segments,
• wherein the waving becomes fully or partly eliminated in the second row formed segments which become oriented by the substantially transverse stretching and
• wherein the waving is essentially maintained in the first row formed segments which do not become oriented by the substantially transverse stretching and become stabilized by a contraction in the second row formed segments.

A process of orienting a film or assembly of films comprising:

• stuffing the film or the assembly into a nip between two circularly or helically mutually intermeshing grooved rollers, groover roller (101) and grooved roller (102), include indentations on crests of teeth of the grooved roller (101) and the grooved roller (102) modifying a frictional engagement of the film or the assembly of the grooved roller (101), wherein the grooved roller (101) rotates at a circumferential velocity higher than a circumferential velocity of the grooved roller (102) so that the film or the assembly enters the nip at a film velocity that is higher than the velocity of the grooved roller (102), wherein the indentations on the crests of the grooved roller (102) are sufficient to reduce the film velocity or to reduce the film velocity to the velocity of the grooved roller (102), and wherein the film or the assembly obtains a fine traverse waving either prior to or while entering the nip to form a waved film or a waved film assembly,
• sequentially stretching the waved film or the waved assembly substantially in a transverse direction upon passing through the nip to form first row segments interspersed with second row segments,
• wherein the waving becomes fully or partly eliminated in the second row segments which become oriented by the substantially transverse stretching,
• wherein the waving is essentially maintained in the first row segments which do not become oriented by the substantially transverse stretching, and
• wherein the waving becomes stabilized by a contraction in the second row segments.