NO118504B - - Google Patents

Description

•Procedure 'for the production of a thin 'ribbon of amber high molecular substance with axial orientation in a direction other than the longitudinal direction. The invention .concerns a .new .continuous, similar method .to clean, skewedly oriented; bands of high polymers and other high molecular substances. It is particularly advantageous to use when -a -high ori- is required; degree of entry, for example by 'preparation-; ling of strong 'foil and plate materials-be-; made of -cross-laminated -oriented plastic film or foils. There are several methods of stretching bands of high molecular weight material in a skewed direction. Usually, two sets of gripping devices are used, which pull the band out in the desired direction. However, this gives 'all- ' •time a rather irregular material.-I have found it -impossible to 'use such

methods -for -cold drawing -in connection médi

production of !cross laminates, as the cold-'drawn strips never-become-adequately 'plane -to'

'and' could be placed on top of each other. In that practice

<J>tical operation -is -it -also -a disadvantage that -mani

•need to cut off the edges of the tape therein

the gripping devices have "had 'attachment'.

There -also exist -methods such as ar-J

both without the use of gripping devices. ©no

<:>uses special -arrangements -of -rollers;

etc. These methods are also-unfor-;

participial when it is to be stretched to a hay;

degree of orientation, then -even 'quite ■ small in-j

cuts at the edges will cause breakage;

during' the process.

The present invention does so

possible to produce crookedly drawn, "loud:

-oriented bands much -more regularly' than -so far, -and without the risk of -difficulties arising during -the stretch as a -' •result of -defects in an edge. Besides, 'can! the production takes place with very simple equipment. <:> According to the present invention, the skew-oriented band is produced from a tubular film or a tubular foil of the "high molecular weight substance. The tube is oriented by stretching and then cut into one or several bands, as the cut does not follow the orientation. In this way, bands can be produced with an arbitrarily skewed orientation. The F-film or foil tube can, for example, be formed by extrusion and is possibly blown up. In those -cases where -the 'high molecular weight substance should be melted, 'half-melted' -or say -form -of viscous -solution when it is oriented, -it is -of course -best -to -carry out the stretch 'when the substance •leaves -the -mouth of the -extruder. In the case of cold drawing and stretching in a thermoelastic state, the stretching process should, on the other hand, be separated from the extrusion. In one embodiment of the invention, the film or foil tube is first stretched in the longitudinal direction , and then cuts it up after a -spiral or after several parallel spirals. This embodiment is preferred <;>in most cases where the band's orientation angle -should be -less -than -approx. *60—^0°.

In another embodiment of the invention, the film or foil tube is twisted at the same time as or after it is stretched lengthwise. <f>Der.ved -it gets spiral orientation. Then

■cut Dry to length or to a spiral that does not follow the orientation. This -method -is preferred when -it

strips must be produced with a perpendicular or nearly perpendicular orientation.

In all cases, it is preferred to stretch the film or foil tube over a mandrel. The mandrel is particularly important when cold drawing. If a thin strip or tube is cold-drawn for ex-

pile in an ordinary drawing bench, the movement that leads to orientation proceeds, as is known, within a rather narrow zone.

This causes an abrupt contraction of width and thickness (the so-called "shoulder effect"). The abrupt width contraction results in irregular stress distribution in the yield zone, and therefore the stretched strip or tube acquires an irregular orientation and wrinkles.

ket form. I have found that by using

ke a mandrel forces the flow zone out over a me-

get a larger area, and in that way eliminate

removes the irregularities almost completely.

When drawn in the thermoplastic state

shape, the mandrel also has a certain significance for the regularity. It also prevents the thermoplastic self-adhesive pipe from

close together.

Further details regarding the be-

written methods appear from the drawings. They schematically reproduce two for-

different methods for making ribbons.

Figure 1 shows the production of 45° orien-

tert bands, and Figure 2 production of wine-

kelright oriented bands. All devices, except the cutting device, are drawn in perspective and cut through.

In Figure 1, the pipe 1 is stretched in a draw nozzle apparatus consisting of a spherical steel mandrel 2, the nozzle itself 3, which has a soft coating 4 (for example a thin rubber

replaceable tubes), a steel core 5,

which is electromagnetically attracted by the sun-

noiden 6, and which serves to press the mandrel 2 towards the nozzle 3. The current through the sole-

the node 6 can optionally be controlled automatically.

For example, registrations can be recorded

of the draft in the pipe 1, just after it has left the nozzle 3, and let these records direct the flow. In connection with the draft-nozzle device, there may be heating elements

ments, devices for blowing steam or hot air on the pipe 1, and baths of softening agent.

The pipe 1 is pulled through the nozzle by

using a pair of rollers 7. (The transmission belts are indicated at 15). It continues to a cutting device. This consists of a flat mandrel 8 with a very smooth surface,

two guide drums 9 and a rotating knife 10. The drums 9 and the knife 10 have mutually parallel axes, and these form an angle of .45° with the longitudinal direction of the tube and the mandrel.

When the material leaves the cutting device,

it is cut up into a 45° oriented band.

This is wound up on the coil 11, which is

brought so that the band is pulled away from the knee-

vein 10 at a certain angle with the egg, for example at approx. 10°. This makes it easier to

the ring.

In Figure 2, the nozzle 3 is rotating. The direction of rotation is shown by arrows. Moreover, the roller pair 7 from fig. 1 replaced with a special pulling device, which can keep the pipe 1 stretched, even if it is exposed to torsional stresses. Such a drawing apparatus can, as shown here, consist of a mandrel 12, which has a smooth surface, and which is attached to the spherical mandrel 2, and of a roller 13, which is driven by a circuit of drum-

ler 14 (only two are shown). The ring-shaped roller 13 is best made of rubber with a steel wire skeleton.

The nozzle 3 and the roller 13 rotate in such a relationship that the tube 1 becomes 45° from the

entertained. The cutting device is exactly the same as that shown in figure 1. As it cuts the pipe up following a 45° spiral, which is mirror-

the image of the spirals that follow the orientation

gene, the manufactured ribbon is perpendicularly oriented.

By both the production methods which

is shown in the drawings, the orientation is done by drawing over the mandrel. This is the pre-

drawn method, but it also falls within the scope of the invention to draw without the use of a mandrel. Instead of drawing the pipe, one can also use compressive stretching (cold rolling), or a combi-

nation of tensile and compressive strain-

nothing. The cutting apparatus shown in the drawings is only one example. Many other device types can be used.

It has previously been mentioned that the product manufactured according to the invention is particularly advantageous for use in the production of cross-laminates composed of stretched plastic

foils. Another important area of application is the production of birefringent film for Polaroid filters. Finally, the invention is me-

get suitable for the production of ribbons, which are to be split up into an oriented coherent fiber structure, for use as yarn or in non-woven textiles.

Claims (2)

1. Process for the continuous production of a thin strip of high-mol. chylar material with a uniform directional orientation, where the direction of orientation forms an angle with the longitudinal direction, characterized by a thin tubular foil being stretched hot or cold in a known manner in such a way that the material acquires a significant directional orientation, after which the tube is cut into one or more band, by section following one or more lines forming an angle with the direction of orientation; for example so that the foil tube is first stretched lengthwise and then cut along a spiral line or along several mutually parallel spiral lines. 2. Change of procedure according to claim 1, characterized by, that the foil tube is twisted at the same time as or after it is stretched lengthwise, so that it is oriented along spiral lines and then cut into one or more strips, either along or along one or more spiral lines of a different inclination than the direction of orientation.