JPH064278B2 - Operation method of simultaneous biaxial stretching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the operation of a simultaneous biaxial stretching device equipped with a thermoplastic resin or an endless link device that continuously stretches biaxially in the length direction and the width direction simultaneously. It is about the method.

[Conventional technology]

As for the conventional apparatus, as described in JP-A-49-40369, the physical properties of the film after stretching are made uniform over the entire width of the film, and an apparatus suitable for speeding up and widening is manufactured. For ease, y = Y / Xx, where XY is the final draw ratio in the length and width directions and xy is the draw ratio in the length and width directions at any time during drawing) It is ideal to make the locus of. When the link is brought closer to the ideal straight line, when the link suddenly changes in the width direction near the entrance of the extension part, a large force is applied to the link, which is the film gripping device, and the rail, which is the guide groove that restricts the running of the link. This will damage the device. Therefore, in the initial stage of stretching, the increase in the stretching ratio in the length direction is made larger than that in the width direction, and in the latter stage of stretching, the increase in the stretching ratio in the width direction is made larger than that in the length direction to keep the balance. I was driving.

[Problems to be solved by the invention] In recent years, sheet-like materials have been made into various types such as ultra-thin film and special molecular orientation, and physical properties of conventional films, particularly molecular orientation in the plane direction of the film, are strictly required. . The above conventional technique is limited to the range of X≈Y, and in particular, X> Y, | α
No consideration was given in the case of | ≧ 0.3 A (A is a smaller value of X and Y).

An object of the present invention is to provide a method for operating a simultaneous biaxial stretching device capable of producing a film having high dimensional stability under a stretching condition in which a final stretching ratio X in the length direction is larger than a final stretching ratio Y in the width direction. Especially.

[Means for Solving the Problems]

The above-mentioned object is ideally achieved by stretching along a linear stretching locus of y = Y / Xx, but widening,
In the case of producing a sheet having excellent dimensional stability with a specific molecular orientation under the condition of high speed, the stretching ratio in the longitudinal direction and the stretching ratio in the transverse direction are determined by predetermined stretching with respect to each stretching ideal straight line. It is achieved by controlling with a magnification and operating under limited trajectory conditions.

[Action]

In the initial stage of stretching, the increase in the stretching ratio in the width direction is kept to a necessary minimum, and by repairing the shortage in the latter stage of stretching, the load acting on the link and rail can be suppressed. On the other hand, from the functional aspect of the film, in order to cover the unbalance due to the above, the increase in the stretching ratio in the machine direction, contrary to the width-direction stretching ratio locus, is made as large as necessary in the initial stage of stretching and in the latter stage of stretching. By making it small, it becomes possible to achieve balance.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. In the figure, the sheet 1 is continuously stretched biaxially in the direction of arrow E continuously in the direction of arrow A while its both ends are held by the grippers 2 of the link device 3. The link device 3 is endlessly driven by the sprockets 7, 8 and 9, and its movement is restricted by the guide rails 4, 5, 6 arranged at both ends of the sheet-like material. B is a link pitch adjusting section, C is a sheet gripping section, D is a preheating section, E is a stretching section, F is a heat treatment section, G is a sheet separating section, and H is a return section.

The movement of the link device 3 in the extension part, that is, the magnification locus is arbitrarily determined by the shapes of the guide rails 4, 5, and 6. FIG. 3 shows the optimum stretching conditions when X> Y. The horizontal axis represents the length of the stretching process, and corresponds to the stretching section E in FIG. That is, the point 0 indicates the stretching start point and the point 1.0 indicates the stretching end point. The vertical axis represents the flow direction (M, D) draw ratio and the transverse direction (T,
D) and the draw ratio are shown, respectively.

The stretching ratio in the longitudinal direction (M, D) is 70
% Or less, the stretching is performed earlier than the ideal M, D magnification straight line, that is, in the range where the stretching magnification is increased, and the stretching is carried out earlier, and the latter stage of the stretching, the step exceeding 50% of the stretching step, preferably 7
Stretching is delayed in the range below the ideal straight line in the process of exceeding 0%.

On the other hand, with respect to the draw ratio in the width direction (T, D), the film is stretched late in the first half of the drawing process, preferably 40% or less and below the ideal straight line, and the subsequent T, D ratio is ideal. Stretching is performed earlier in the range above the curve.

According to this embodiment, it is possible to smoothly operate for widening and speeding up without applying a large force to the link and the rail in the initial stage of stretching.

〔The invention's effect〕

Advantageous Effects of Invention According to the present invention, it is possible to operate to produce a dimensional-stable film having a specific molecular orientation under a stretching condition in which the final stretching ratio in the length direction is larger than the final stretching ratio in the width direction. There is.

[Brief description of drawings]

FIG. 1 is a plan view of a simultaneous biaxial stretching device according to an embodiment of the present invention, FIG. 2 is a partial plan view showing details of the relative relationship between a link device and a rail in the stretching process, and FIG. FIG. 6 is an operation characteristic diagram showing a locus of stretching ratio in FIG. 1 ... Sheet-like object, 2 ... Grip, 3 ... Link device, 4, 5, 6 ... Guide rail, 7, 8, 9 ... Sprocket, E ... Stretching section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Taka ▼ Yoshiyuki Mura 794 Azuma Higashitoyoi, Shimomatsu City, Yamaguchi Prefecture Inside the Kasado Plant, Hitachi Ltd. (72) Masahiro Fujisaki 794 Higashitoyo Higamatsu, Shimomatsu City, Yamaguchi Prefecture Address Hisao Nao Tanaka Examiner, Kasado Works, Hitachi Techno Engineering Co., Ltd.

Claims (2)

[Claims] 1. An endless link device in which link plates of equal length are connected in zigzag, and a film gripper provided at one end of the link device to guide the link device are provided at both ends of the film, and a plurality of guide rails are provided. In the operating method of the simultaneous biaxial stretching device in which the link device is driven by the sprocket, the film is simultaneously stretched in the longitudinal and lateral directions, when the final stretching ratio in the longitudinal direction is larger than the final stretching ratio in the lateral direction, the stretching in the longitudinal direction is performed. A method for operating a simultaneous biaxial stretching device, characterized in that the stretching ratio and the stretching ratio in the transverse direction are controlled at predetermined stretching ratios with respect to the respective ideal stretching straight lines. 2. In the longitudinal stretching ratio, 70% or less of the total stretching step is stretched earlier than the ideal straight line,
In the stretching step beyond that, the stretching is slow, and in the transverse stretching ratio, the first half range of the entire stretching step is stretched with respect to the ideal stretching straight line, and in the stretching step beyond that, it is stretched early. The method for operating a simultaneous biaxial stretching device according to claim 1, wherein the method is controlled by two loci of stretching magnification.