DE1660576A1 - Process for making curled split fibers - Google Patents

Description

PATENT LAWYERS ,. DIPL-ING. CUfWWALJfACH DIPL-ING. GÜNTHER KOCH 1660576 DR. TINO HAIBACH

8 MUNICH 2, DEN

OUR MARK: Iq 498

Polymer Processing Research Institute, Ltd. Tokyo / Japan

Process for making crimped split fibers.

The invention relates to a method for producing split fibers from a stretched thin film or Ribbons that can be puckered very easily when heated.

In particular, the invention is for making particularly well crimped split fibers using the method according to the patent ...... (patent application P 38.375 VIIa / 29a), the latter with sliding friction a thin film stretched in one axis under tension over the rough surface of a rotating file or the like. and the film is split into fibers. To the

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Puckering of fibers in the manufacture of synthetic fibers are various methods have heretofore been proposed. For example can be used in the production of synthetic fibers according to the so-called viscose process, in which coagulation liquid is applied to the viscous fiber that comes out of a nozzle in the Coagulation bath is squeezed out at right angles to the direction of spinning the Paser is applied, the coagulation asymmetrical going on on either side of each fiber. In this case, when appropriate tension is applied to the fiber a better molecular orientation of the fiber on the rapidly coagulating side than on the slow coagulating side. It is known that such an asymmetrical coagulated fiber can be easily curled by applying heat to it, the more oriented Page is held inside.

It is also known that in a method of melt-spinning fine fibers from compounds such as polyvinylidene chloride and polyethylene and the like, asymmetrical coagulation can take place on both sides of the fiber, that cold air is fed to the fibers at right angles to their spinning direction immediately after exiting a nozzle will. After stretching, when the fibers are relaxed and heated to a suitable temperature, there may be many pimples are produced in the fibers

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Further, it is known that a straight crimp can be given to a conjugate fiber by extruding two different kinds of polymers, each having a different heat contraction, through a single nozzle and heat-treating the conjugate fiber thus squeezed. Of course, the above-mentioned process for producing crimped synthetic fibers also know applied for crimping split fibers ·

However, contrary to expectation, the present invention has found that there is a large difference in the degree of curling of the split fibers depending on the combination of the above-mentioned method of making crimped fibers with the method of splitting an axially stretched film, that is, it has been found that such a conventional process cannot be directly applied to this novel process. In other words, it has been found in the production of crimped split fibers by the process of the invention that the use of such a stretched film with different heat contraction on each side alone has proven unsuitable and, in addition, the special condition that the rile film surface with the higher thermal contraction is in contact with a rough surface as an important factor to be provided for the intended purpose.

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This particular condition has been made through extensive experimentation determined within the scope of the invention.

In a process for the production of split fibers after

the patent (patent application P 38.375 VIIa / 29a) i.e.

in the method in which with sliding friction f »in stretched thin film under tension over the rough surface of a rotating bearing od. The like. Is passed to Obtaining split strands was determined by an experiment that in the case of using an asymmetrically coagulated and post-stretched thin film, the degree of curling obtained by heating is entirely determined by the choice of whether the upper side of said film or its back is applied to the surface of the bearing. This can largely better crimp by applying the top side, i.e. the more shrinkable or better stretched side of the film on the surface of the skin can be achieved in comparison to the case when the back side, i.e. the less shrinkable or less stretched side of the film over the file with Friction is directed.

The reason for this can be explained as follows. When a stretched Film moved with friction over a rough surface under tension in the same direction as the film was stretched there will be an improvement in the molecular orientation in

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the film surface, which is in contact with the rough surface is obtained as a result of the frictional heat generated and the frictional movement. Therefore, if the pilm surface, which has a higher heat contraction, i.e. better molecular weight Orientation, using the bearings for splitting in strips with friction The difference in the degree of molecular orientation between the two surfaces of the film is sufficient can be reinforced to create a crimp when the generated split strands are heated.

If, on the other hand, the pilm surface, which has a lower heat contraction has, with sliding friction passed over the file for splitting into fibers, the difference may be in the molecular Orientation between the respective surfaces can be compensated for, so that a desired curl ultimately does not is achieved.

Therefore, for the purpose of the present invention, each conventional method applies a different one to the areas of the film Heat contraction is imparted to success. For example, when using a circular injection mold so-called rubber bag process the squeezed and inflated tubular film quickly under tension thereby cooled, that the outer surface of the film is supplied with cold air becomes, whereby the outer surface and the inner surface of the film

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.Ie are coagulated with a different length of time.

The film obtained in this way is then transferred to a suitable one Cut width, stretched in one axial direction in the »conventional way, the process according to the invention subjected, i.e. the more strongly oriented surface or the outer surface with sliding friction for splitting into fibers passed and heated to obtain the desired curled split fibers.

It is of course possible, the order of the stretching treatment and of the process by which each side of the film is a different one Heat contractibility is reported to change. Bei-Rüielweise can a conventional film first in one axial direction stretched and then one side of the stretched film "at a suitable temperature by touching a rotating rough solid surface are friction treated, which improves the molecular orientation of the friction treated side is than that of the other side of the film, and if then the friction-pretreated Side of the film is brought into contact with the file surface to split the film into fibers the products have excellent crimp, but if the non-rubbed side of the film is brought into contact with the file surface, the split material has a very weak ripple.

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The invention is described in more detail below in connection with the accompanying drawing, namely showing:

Pia. 1 is a schematic view of a preferred device to carry out the process according to the invention and

Pipe. 2 is a schematic view on an enlarged scale a diffuser, which serves to remove the split pasers spread out ..

Fi ° ·. 3 to 6 serve to explain: the examples.

Before being fed to the device, a polymer film is placed in Strips cut and stretched in one axial direction. template of fibers produced by the process according to the invention with and without crimping: sheet A and sheet B are attached.

Highly crystalline polypropylene was first produced by a T-injection ** orm at 24o ° C with a working speed of 2o m each Minute and the film produced in this way is cut into strips each 50 microns thick and 20 mm wide (as shown in No. 1 of the attached Sample Sheet A). The-

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ser film strip was then one direction by eight times its original length in the in saturated steam at 118 ° C to obtain a stretched in an axial direction of film, such as in no. Showing 2 the sheet A whose thickness and width 2o microns and 7.5 mm.

This film strip was fed into a clamping device in Fig. 2 by means of feed rollers 1, which are heated to 115 ⁰ C and advanced by feed rollers 3 and with friction under tension over the rotating sharp edges of a number of knives moves, the the at equal intervals around Circumference of a rotatable roller 4 are arranged. The strip thus treated was then fed to a rotating file 7 by two feed nip rolls 5 and split into fibrils as shown in No. 3 of sheet A. By regulating the relative surface speed of the take-off pinch rollers 6 with respect to the feed pinch rollers 5, an appropriate tension was imparted to the film which is moved with sliding friction over the file 7 in FIG. During this process stage, the strip speed was 60 meters per minute and the peripheral speed of the file 7 was three hundred meters per minute. The fibers split into this catfish were then led to the inlet side of a heating chamber with the aid of compressed air which is supplied to the diffuser 8 via a pipe Io from a source of air (not shown) as in FIG

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PIg. 2 shown.

After crimps have formed and after the split strands have been fixed while they are inside the heating chamber move on a conveyor belt 12, which is driven by two rotating gears 15 and 16, the fixed Crimped fibers, as shown in FIG. 4 of sheet A, are drawn off by means of take-off rollers 14. When treating the The film strip with the rotating edges 4 would be omitted and the strip immediately over the file 7 the feed pinch rollers 5 would be fed, the finished product would have no curl, since a suitable one There is no difference in contraction on either side of the pilm surfaces. This product is shown under No. 3 on sheet B attached.

Instead of the above-mentioned rubbing treatment method, another suitable method can be used which gives the desired difference in contraction on each side of the film. For example, a conjugated film of of the type shown in Example 2 or Example 3 can be produced in that one shown in FIG. 3 or FIG Injection mold is used. A lamination method can be used with the apparatus shown in FIG. 5 or FIG will·

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-lo-

As will be described below, the present invention can be successfully applied to any polymer film provided that the film can be stretched in an axial direction by a conventional method. Examples of these polymers are given in Table 1, in which ¹¹ O "stands for" possible "and" 0 "stands for" confirmed ".

Table 1

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Table 1

O possible

O actually checked

Type of polymer

Orientier ling

Spinning con

procedure- ju- ■

lami- cooling coagu-

kidneys

treated lation

Polyethylene S. θ θ O Polypropylene S. θ θ 0 Polyvinyl chloride S. θ O 0 Polyvinyl alcohol N.T. O O Polystyrene S. O 0 Polyacrylonitrile N.T. θ θ O Polyvinylidene chloride S. θ 0 0 Copolymer thereof θ Poly-iJ-fluoroethylene E.

Copolymers of 6-fluoropropylene and 4-fluoroethylene 'S

other fluororesins S. O O 0 6 nylon S. O O 0 6,6 nylon S. ο - ® Polyethylene terephthalate
lat S. Polycarbonate N Polyurethane rubber N Cellulose T O O Cellulose derivatives

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conju- lami- cooling coagu- frictional yaw njs «en! ation treated

Melt spinning S. O O Dry spinning T O O Wet spinning N emulsion E. A.

O O O O

Manufacturing conditions of the crimped fiber sample (polypropylene)

Spinning process: T-injection mold: degree of polymerization 35oo

Injection temperature: 24o ° C, injection speed: 20 meters / minute Film strip: thickness: 50 microns, width 20 mm, stretching: eight times, temp .: 118 ° C,

Thickness: 20 microns, width 7.5 mm. Friction treatment: Temp. 115 ° C Splitting: strip speed: 6o m / min.,

Peripheral speed of the file

300 m / min.

It is readily possible for the person skilled in the art not to mention here Make changes that are within the scope of the invention.

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The following examples are intended to illustrate the invention but in no way limit it.

example 1

High density polyethylene was extruded through a circular injection mold and formed into a tubular film with a uniform thickness of 60 microns, whereupon a stream of cold air was blown onto the outer surface of the film. After the film was cut into strips (20 mm wide), these strips became up to nine times in length stretched their original length in saturated steam of lo7 ° C to produce the uniaxially stretched films each of which was 7 now wide and 20 microns thick. By using a file (6 mm Diameter) with a rotating speed of five times the strip speed was the aforementioned stretched Strips split into fibers and then heat treated. With this splitting, if the outer surface, i.e. the more stretched one Surface of the film was passed over the skins with friction, the obtained cleaved fiber gave a well-curled fiber, while if the inner surface, i.e., the less stretched surface was passed over the skins with friction, a very weak one Ripple was found on the finished product.

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Example 2

A conjugated film was prepared by extrusion of solutions of a polymer of loo wt.% Acrylonitrile, and copolymers thereof of 92 wt.? Acrylonitrile and 8% by weight of methyl acrylate produced by a T-injection molding and this film obtained is cut into strips and stretched in the longitudinal direction up to fourteen times the original length in steam at 100 ° C. This fair strip of film was 20 microns thick and 6 mm wide. When a test strip was heated, the surface of the acrylonitrile and methyl acrylate cooolyme T »em film curved on the inside. The film strip was then passed over the file with friction in the same manner as described in Example 1, by applying the surface of the above-mentioned copolymer to the file and then heating the split fibers Get fibers.

Example 3

A highly crystalline polypropylene strip was in one Direction stretched up to ten times its original length in saturated steam at li8 ° C. The one in one axial direction Stretched film heated to 115 ° C was rubbed

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moved under tension over three circumferential sharp knife edges, which are spaced in Kleichen around the circumference of a rotor were arranged. The strip treated in this way curved, with the friction-treated surface the inside would be held. This area was, as in Example 1 described, treated to make the strip in Faaa ^ n ai split, and then heated to curled split fibers to obtain.

Patent claims:

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Claims (3)

Patent claims: 1. Proceed "for making ruffled split Fitting from a film stretched in one axial direction and having a different heat contractibility each side, marked by the fact that the film surface with the stronger heat contraction capacity over a rough surface under tension in the stretching direction of the Film is passed with sliding friction and the split fibers obtained in this way without tension be heat treated. 2. The method according to claim 1, characterized in that a conjugated film composed of various kinds of polymers as a film having a different heat contractibility used on each side. 3. The method according to claim I _1, characterized in that the film of different molecular Orientierunr. U.N. 209831/0774 the top and the back as a film of different Heat contraction is used on each side, 4, method according to claim 1, characterized in that a film, one side of which is subject to sliding friction exposed to sharp edges, as film of various heat contra' "tion is used on each side. 209831/0774 Blank page