A film-stretching apparatus in accordance with an aspect of the present invention includes a stretching furnace which has (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace, an airflow in the entrance being controlled so as to be directed toward an outside of the stretching furnace.

A device for stretching a thermoplastic film simultaneously in the longitudinal direction and the transverse direction is provided. The device includes, on each side of the film (F) to be stretched, grasping members for grasping a lateral edge of the film (F), and guide members; first and second guide rails (R1, R2), on which the members and are respectively able to move; first connecting rods connecting the grasping members and the guide members. In an embodiment, each guide member is connected to a single grasping member by one or several of said first connecting rods, and is connected to a first longitudinal adjusting member by one or several second connecting rods connected to the first longitudinal adjusting member; and the device includes adjusting means for adjusting the position and orientation of said first longitudinal adjusting member relative to said first and second guide rail (R1, R2).

The invention relates to a film-drawing machine, including a furnace, through which one strand of an endless chain of clamps passes, driven by at least one toothed wheel, characterised in that at least one toothed wheel is inside the furnace, is rotated by its own gear motor surrounded by a casing, placed in the furnace and cooled by cooling means, and is mounted on its own movement device, so as to pass from a withdrawn position, in which it does not mesh with the chain, to a drive position, in which it meshes with the chain. The invention also relates to a method for starting said film-drawing machine.

A film stretching apparatus includes: a pair of first and second link devices configured to be able to carry and stretch a film and each composed of a plurality of links coupled to form an endless chain; a heat treatment unit configured to cover a central portion of the first and second link devices and perform a heat treatment to the film; a sprocket (first link drive mechanism) arranged outside the heat treatment unit and on an inlet side of the film and configured to drive the plurality of links; a sprocket (second link drive mechanism) arranged outside the heat treatment unit and on an outlet side of the film and configured to drive the plurality of links; and a sprocket (link adjustment mechanism) arranged outside the heat treatment unit and on the outlet side of the film and configured to reduce a pitch of the plurality of links.

This stretching device comprises a guide rail, first clamps of a first type and second clamps of a second type each intended to grip the same longitudinal edge of a film and alternately disposed along the guide rail, and an endless chain connected to the first and second clamps and configured to drive the first and second clamps along the guide rail, the endless chain being deformable between a first state and a second state in which the first and second clamps are respectively disposed close to or distant from each other. Each first clamp and each second clamp respectively include a primary guide roller and a secondary guide roller configured to cooperate with the guide rail, the first and second clamps being configured such that when the endless chain is in the first state, the primary guide roller of each first clamp and the secondary guide roller of each second clamp adjacent to said first clamp overlap at least partially.

Provided is a method capable of producing a retardation film suppressed in biaxiality, having a small Nz coefficient, and having a slow axis in an oblique direction with high production efficiency. The production method for a retardation film of the present invention includes: holding left and right side edge portions of a film to be stretched with left and right variable pitch-type clips configured to have clip pitches changing in a longitudinal direction, respectively; preheating the film; reducing, under a state in which a position at which the clip pitch of the clips on one side out of the left and right clips starts to reduce and a position at which the clip pitch of the clips on another side starts to reduce are set to different positions in the longitudinal direction, the clip pitch of each of the clips to a predetermined pitch to subject the film to oblique stretching; and releasing the clips holding the film.

A method for manufacturing a stretched film, including stretching a long-length resin film in an oven by grippers while conveying the resin film to pass the resin film through the oven to manufacture a long-length stretched film having a slow axis within an average angle range of 10 or more and 80 or less with respect to a width direction thereof, wherein the oven has a stretching zone and a heat setting zone in this order from an upstream side, and the method includes the steps of: holding the both edges of the resin film by the grippers; stretching the resin film in the stretching zone; releasing the resin film from the grippers in the heat setting zone; and subjecting the resin film released from the grippers to a heat treatment at a temperature higher than Tg10 C. and lower than Tg for 10 seconds or more in the heat setting zone.

A film-stretching apparatus in accordance with an aspect of the present invention includes a stretching furnace which has (i) an entrance through which a material film is transferred into the stretching furnace and (ii) an exit through which the material film having been stretched is transferred out of the stretching furnace, an airflow in the entrance being controlled so as to be directed toward an outside of the stretching furnace.

A film-stretching apparatus in accordance with an embodiment of the present invention includes a stretching furnace which is divided into a plurality of air amount control zones. In a case where the number of the plurality of air amount control zones is seven, a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an entrance side of the stretching furnace is controlled so as to be larger than a total amount of air to be discharged from, out of the plurality of air amount control zones, three air amount control zones which are located on an exit side of the stretching furnace.

A clip-type stretching apparatus includes a main link device, a sub-link device, a standard rail, a pitch setting rail, and drive sprockets, the main link device including a first clip support member having a clip, the sub-link device having the clip, the standard rail defining a circulation route of the clip, the pitch setting rail setting a pitch between the first clip support members by a distance from the standard rail, the drive sprockets engaged with a drive roller provided in a first shaft member of the first clip support member and causing the first clip support member to travel.