DD256287A1 - METHOD AND DEVICE FOR CONTINUOUS SOLID EXTRUSION - Google Patents

Abstract

The invention finds application in the production of highly oriented fibers and films or mixtures and dispersions of polymeric materials in polymer processing. The essence of the method is that constructed in a solidified, profiled and dimensional continuously extruded strand of the necessary to achieve the extremely high degrees of deformation or compulsory mixtures pressure and the required Temperaturverhaeltnisse and then the high degrees of deformation or compulsory mixtures are set. The apparatus shown in FIG. 1 for carrying out the method consists of a longitudinally grooved extrusion cylinder and an extrusion screw therein, which begins and ends with a pitch zero slope, the gears in the negative profile of the zugefuehrten, profiled, solidified and massive strand correspond to the Feeding area, which is limited to the first flight with zero pitch, a profiled feed roller is installed parallel to the axis and the Duese is perpendicular to the direction Foerderrichtung in the last flight of the zero pitch on the extrusion cylinder. Fig. 1

Description

For this 1 page drawing

Field of application of the invention

The invention finds application in the production of highly oriented fibers and films or blends and dispersions of polymeric materials in polymer processing technology.

Characteristic of the known state of the art

For solid extrusion, the following techniques are known:

Stamp extrusion, d. H. Extruding the sample under high pressure at temperatures below the melting temperature of the polymer through a conical round die; rarely through a slot die.

Hydrostatic extrusion, i. a polymer strand is pressed through a predominantly conical round die, the high pressure being transferred to the polymer by means of a liquid (eg castor oil). The liquid also forms a film between the polymer strand and the nozzle wall; whereby a more uniform orientation of the extrudate and a reduction of the extrusion pressure compared to the stamp extrusion is achieved.

Coextrusion, i. longitudinally slotted or bored samples are extruded with inserted films or round bars; Often an additional trigger force is applied.

Another technique for producing highly oriented fibers is die drawing, in which a polymer strand is slowly drawn through a heated die under the action of a peel force imposed on the product.

(Dröscher, M .: Solid-State Extrusion of Semicrystalline Copolymers, in: Advances in Polymer Science 47, pp. 119-138, Springer-Verlag Berlin Heidelberg 1982;

Hope, P.S .; Richardson, A .; Ward, I.M .: Polymer Engineering and Science 22, 1982, pp. 307-313; Ward, I. M .: The Applied Macromolecular Chemistry 109 / 110,182,1759, pp. 25-39; Ward, I. M .: The preparation, structure and properties of ultra-high modulus flexible polymers, in: Author collective Key polymers, properties and performance, Akademie-Verlag Berlin 1986;

lnoue, N .; Nishihara, M .: Hydrostatic extrusion, theory and applications, Elsevier Applied Science Publishers Ltd, London and NY 1985; Zachariades, AE; Porter, RS: J. Macromol. Sci. 19, 1981, 31, pp. 377-386) Disadvantage of ο. G. Methods and devices consists in the discontinuous mode of operation. The nozzle drawing also allows only a conditional deformation and thus increase in strength compared to the stamp extrusion and the hydrostatic extrusion

 With the DD-WP B29F 2605568 a method and an extrusion device for forming flowable masses is set forth,

wherein the temperature profile in the extrusion cylinder allows the construction of very high pressures and the essential thrust forces are taken up by mutually promoting screws. For this purpose, a flowable mass (molten polymer) is continuously supplied to an extrusion device under pressure in a flowing state and the flowing mass is then from the outside via the extrusion cylinder but also from the inside via cavities of a screw after entering an extrusion cylinder and before it is ejected cooled to a temperature below the freezing point. The nachfließende and the solidified mass are promoted by the screw in the direction of a discharge point of the extrusion cylinder.

The pressure is built up in the solids area.

On the one hand, it is proposed to expel the solidified mass from the extrusion cylinder and, on the other hand, to bring the solidified mass back into a flowing state before it is expelled, and then to remove it from the extrusion cylinder in this form.

In this technical solution, the disadvantage is that at the required high discharge pressures shearing of the polymeric mass on the cylinder wall can not be avoided because the shear stresses in the melt and shortly below are relatively low.

Further cooling of the polymer material brings an extension of the screw and thus an increase in the required torque with it. This increases the demands on the torsional strength of the screw core.

The solidification of the polymer material under high pressures produces a largely defect-free structure; However, this further makes a further deformation much more difficult or impossible.

Object of the invention

The object of the invention is to provide a method and a device for solids extrusion, whereby a continuous realization of high levels of orientation or of forced mixtures of polymer materials is made possible.

Explanation of the essence of the invention

The invention has for its object to provide a method and an apparatus which make it possible to continuously deform polymer materials under such high pressures that degrees of deformation are achieved, as they are known from the discontinuous solids extrusion or forced mixtures of materials to produce, as they can not be achieved with conventional machinery and equipment

 According to the invention the object is achieved in that known

• a continuous strand is extruded, the profile of a defined geometric shape, such. B. a semicircle, a circle section, an ellipse section, a rectangle corresponds;

• a calibration and profiling of the continuously extruded strand takes place;

• a targeted preorientation of the continuously extruded strand is generated;

• on the flat side of the continuously extruded strand, a groove-shaped transverse profiling is applied; that according to the invention

• By the solidified, profiled and dimensionally continuously extruded strand of pressure required to achieve the extremely high degrees of deformation or compulsory mixtures built up and the required temperature conditions and then

• the high degree of deformation or compulsory mixtures are set.

The device for carrying out the method consists in its structural design of a grooved extrusion cylinder and an extrusion screw therein, which begins and ends with a zero slope and their courses in the negative profile that of the continuously extruded, profiled and solidified strand to be oriented or zwangszumischenden correspond. At the catchment area, which is limited to the first flight with zero pitch, a profiled feed roller is installed parallel to the axis. The nozzle for setting the orientation or forced mixing is located perpendicular to the conveying direction in the region of the last flight with zero pitch on the extrusion cylinder.

The continuously extruded profiled and solidified strand to be oriented or forcibly mixed is continuously drawn into the device for carrying out the process due to the flight pitch zero in the feed area and the profiled feed roll installed there, which ensures curving, feeding and pressing of the strand.

In the conveying direction of the necessary to realize the required degrees of deformation or compulsory mixtures pressure of at least 800bar are constructed and the required temperature conditions, which are below the melting temperature set.

By positioned perpendicular to the conveying direction ejection, connected to the sealing screw tip cylinder in the conveying direction, the back pressure forces are kept minimal on the screw bearing.

The essential pressure is in the range of the last gear in the conveying direction with the slope zero, in particular between the last webs and the cylinder wall.

In the profiled plan side of the strand to be oriented or forcibly mixed, the grooves in the extruder cylinder correspond to the profiling of the flat strand side. In the area of the last gear in the conveying direction with the slope zero of the screw, the grooves connected with a small diameter increase of the cylinder run out.

The strand is ejected in this area perpendicular to the conveying direction by a temperature-controlled nozzle special geometry and thereby set the required degree of deformation or realized the forced mixing.

embodiment

In Fig. 1, a single-screw extruder 1, an active pair roller-roll 3 and a device 4 for performing the method are shown.

The invention will be explained below by way of example.

-3- ΔΧ3Ό

A polyethylene granulate (PEHD, molecular weight 152,000, MFI ₅ 16) is processed in a single-screw extruder 1 to form a continuous strand 2 whose profile corresponds to a semicircle. The extruder 1 is an active pair roller-roll 3, which has a strand cross-section (semicircle) corresponding negative profile, downstream, is calibrated in the continuously extruded strand 2 and profiled. The deduction rate of the pairing roller-roller 3 is adjusted so that in the strand 2, a pre-orientation is generated. Through the upper roller of the active pair roller-roller 3, the flat side of the strand 2 receives a transverse profiling. Thereafter, the solidified profiled and dimensionally stable strand 2 of the device 4 is fed to perform the method, the worm 5 has semicircular worm threads corresponding to the negative profile of the strand 2. The worm 5 begins and ends with a zero slope gear.

By the course of the slope zero in the catchment area and there profiled, corresponding to the upper roller of the active pair roller-roller 3, feed roller 6, a continuous drawing of the strand 2 is possible.

In the conveying direction of the necessary to achieve the required degree of deformation pressure of 1000 bar are built and set the required temperature of 132 ⁰ C via Temperiersegmente 7.

The grooves 8 in the extrusion cylinder 9 correspond to the profiling of the flat side of the strand. 2

In the region of the last in the conveying direction of the screw 5 with the slope zero of the strand 2 is ejected by a tempered to 130 ° C conical nozzle 10 perpendicular to the conveying direction and thereby receives the required degree of deformation.

When compulsory mixtures are produced, a premixing and processing of the polymer granules into a continuous strand 2 takes place in the single-screw extruder 1.

The forced mixing takes place in the conical nozzle 10 of the device 4 for carrying out the method.

Claims (5)

1. A process for continuous solids extrusion, in which a continuous strand whose profile corresponds to a defined geometric shape, extruded, calibrated and profiled and targeted preoriented and profiled on the flat side is grooved cross-profile, characterized in that in the solidified, profiled and dimensionally continuous extruded strand a pressure of at least 800 bar constructed and temperature conditions up to 20 K below the melting temperature and then the high degrees of deformation or compulsory mixtures are set. 2. A method for continuous solids extrusion according to item 1, characterized in that the solidified, profiled and dimensionally continuous extruded strand is separated into individual sections before setting the high degrees of deformation or compulsory mixtures. 3. Apparatus for carrying out the method according to item 1, consisting of a grooved extrusion cylinder O) and an extruder screw (5) therein, characterized in that the extrusion screw (5) begins and ends with a pitch zero slope, whose courses in the negative profile that of the supplied, profiled, solidified and dimensionally stable strand (2), at the catchment area, which is limited to the first helical flight with zero pitch, a profiled feed roller (6) is installed parallel to the axis and the nozzle (10) perpendicular to the conveying direction in the area of the last flight with zero pitch on the extrusion cylinder (9). 4. Apparatus for carrying out the method according to item 3, characterized in that after the nozzle (10) take-off rollers are installed. 5. Apparatus for carrying out the method according to item 3, characterized in that the nozzle (10) is a multiple nozzle.