DE1454865B2 - METHOD FOR PLASTIFYING HIGH MOLECULAR POLYAETHYLENE OR POLYPROPYLENE IN A SINGLE SCREW PRESS - Google Patents

Description

Polyethylene σΒ ¹²⁰
(Tensile strength
speed kp / cm ² ) (Tear resistant
speed kp / cm ² ) OB ¹²⁰
(Elongation at break
° / o) before extrusion
after extrusion 32
32 145
157 910
725

3 4

It was carried out on a hydraulic press at a Mechanical values of the plate:

Temperature of 200 ⁰ C ₅ a pressure of 60 kp / cm ² notched impact strength, pointed notch .. kp cm / cm ² 33

30mm. pressed into a plate. Em reduction in tensile strength 20 ° kp / cm ² 185

Material could not be determined. The tensile strength was 20 ° '.'. '.'. '.'. '.'. '.'. '. I kp / cm ² 184

the following values were measured: 5 _{elongation at} break ⁵ _{g 20} ° _{ofj 125}

Example 4

On a single-screw extruder (as in Example 2) ίο was extruded from a polyethylene granulate with a molecular weight of about 1,000,000 and a wood flour content of 50%, a tape with the dimensions 100 x 3 mm, which then on a hydraulic press at a temperature of 180 ⁰ C and a pressure of 80 kp / cm ² 10 min. Was pressed to form a plate. The temperature program for the 6 heating zones during extrusion was 20, 20, 175, 190, 170, 170 ° C. A perforated disk with a 4 mm hole diameter was installed between the IV and V heating zones. At a speed of 20 rpm, an output rate of 10 kg / hour. achieved.
Mechanical values of the plate:

Notched impact strength, pointed notch .. kp cm / cm ² 16

Impact strength kp cm / cm ² 56

Tensile strength 20 ° kp / cm ² 417

Elongation at break% 60

Example 5

A single-screw plasticizing injection molding machine was charged with a polyethylene granulate (molecular weight about 500,000). The heating zone of the screw cylinder was cooled compared to the use of slightly melting injection molding materials in the area of the feed zone and the first cylinder zone, so that when the screw moved backwards, molten material could not get into the filling zone, thus ensuring proper conveying of the screw. It is thus possible to let the rhythm of the worm work run smoothly, which ensures that the spraying works properly. The high molecular weight polyethylene melted in the last part of the cylinder is well plasticized when it is injected through a nozzle. Molecular degradation did not occur.
The following values were measured:

The impact strength was unchanged.

On the same extruder was a polyethylene granulate with a molecular weight of about 500,000 with a temperature program of 20, 40, 175, 195 ° C, a speed of 34 rpm, and an output from 18 kg / hour moved to a tape of the same dimensions.

Example 3

A powdery mixture of a polyethylene with a molecular weight of about 500,000 and 20% chalk was processed on a single-screw extruder (as in Example 2) to form a tape measuring 70 × 2 mm , 40.155, 195, 170, 170 ⁰ C. between the heating zones IV and V were installed a perforated plate with 3 mm hole diameter and two screens having a mesh size of 1.5 to 1 mm. the incorporation of the perforated disc and the sieves and by cooling the heating zones V and VI to 170 ^° C., the backflow of the mold was supported.

At a speed of 20 rpm, an output of 20 kg / hour. can be achieved. As in Example 2, the extruded tape was pressed into a sheet.
Mechanical values of the plate:

Notched impact strength, pointed notch., Kp cm / cm ² 90

Tensile strength 20 ° kp / cm ² 225

Tensile strength 20 ° kp / cm ² . 330

Elongation at break 20% 550

A polyethylene granulate with a molecular weight of about 500,000 and a chalk content of 60% was processed on the same extruder at a temperature program of 20, 20, 155, 195, 180, 180 ^° C., at a speed of 20 rpm, and an output from 20 kg / hour driven to a belt and pressed into a plate.

Polyethylene σΒ ¹²⁰
(Tensile strength
speed kp / cm ² ) 0R ¹²⁰
(Tear resistant
speed kp / cm ² ) OR ¹²⁰
(Tear
strain %) before spraying
after spraying 32
32 140
145 910
934

Claims (2)

1 2 The invention is therefore based on the object of a patent claims: to find a method that makes it possible to use these high molecular weight polyolefins on single-screw Ex- 1. Process for plasticizing filled trudern. This task is carried out according to the or unfilled, high molecular weight polyethylene 5 invention solved by the fact that the abandoned or polypropylene with viscometrically determined polyethylene or polypropylene in a single-screw molecular weight above 200,000 at which the extruder is exposed to a slowly rising material the filling zone of a screw press to have the compression ratio below 1: 3 and is then melted, the extruder screw is suspended and it through characterized in that io cooling of the extruder screw and / or the screw abandoned polyethylene or polypropylene in kenzylinders in the area of the filling zone and in the a single screw extruder the action of an area adjoining the filling zone below the maintains a slowly increasing compression ratio of the softening point. below 1: 3 having extruder screw from- By the temperature control according to the invention not only prevents any thermal degradation by cooling the extruder screw and / or the screw cylinder in the loading of the high molecular weight polyolefin, but achieved rich in the filling zone and in the areas adjacent to the filling zone, the frictional heat is dissipated so that no bordering areas below the softening melting and sintering of the polyolefin in the area point holds. of the first two cylinder zones and the required 2. The method according to claim 1, characterized in that ao lent pressure for conveying the very viscous masses draws that the abandoned polyethylene is reached. or polypropylene mass during the passage. The temperatures of the softening zone are in vented through the extruder. of the order of magnitude usual for polyethylene and polypropylene from about 170 to 250 °, in particular between 25 180 to 200 °. By backing up the mass by means of built-in Perforated disks or sieve plates are used to ventilate the conveyed mass in a known manner The invention relates to a method for plastification during the passage through the extruder screw, decorate filled or unfilled, high-molecular 30 by applying a vacuum in the appropriate Kularem polyethylene or polypropylene with viskosi- areas of the screw cylinder still supported metrically determined molecular weights above 200,000. in which the material of the filling zone of a screw The compression ratio of the extruder screws press abandoned and then melted is appropriately chosen low, z. B. below will. . 35 1: 2.0. Low molecular weight polyolefins can easily be 1
in single-screw extruders with molds as well as in single-screw extruders, the injection molding machines are connected upstream of a single-screw extruder with 60 mm screws. Polykene diameter, a screw length of 20 D and ethylene with η _Τ εα values in the range of 2 to 4 can be processed well with a compression ratio of 1: 2 stoffe ", 1955, p. 589 and" Kunststoff-Extrudertechnik "500,000 (RSV value 12) abandoned,
by Dr. Ing.Gerh. Schenkel, Carl Hanser-Ver. The abandoned material was at a Tempelag Munich, 1963, p. 240). temperature control in the four heating zones of the cylinder of High molecular weight polyethylene and polypropylene 45 20,125,160,180, 190 ° C and a screw speed with viscometrically determined. Molecular weights above 50 rpm, with an output of 22 kg / hour. Up to now, half 100,000 have been able to be melt-plasticized due to their plasticity and by means of a belt tool with a Behavior not ejected on such a single-screw extrusion nozzle dimension of 70 2 mm, but only with the help of twin screw Ex- At 60 rpm, the output increases to 30 kg / hour. trudern are processed. 50 The molded band was well plasticized and So far, attempts have been made in high-molecular art without molecular degradation, substances to raise the temperature very far by one. . to ensure sufficient plasticization. Here example / however, there is a very strong molecular breakdown. A single screw extruder with a screw According to US Pat. No. 2,449,355 one can have a diameter of 60 mm and a screw length of 55 by cooling the extruder in the area of the filling zone 15 D and a compression ratio of 1: 2.8 the thermal breakdown of the molecular weight of was with stabilized polyethylene powder with a Reduce plastics. It is also known, viscometrically determined molecular weight of that for the processing of polyethylene long cylinder loads about 500,000. The 60 The temperature in the four consecutive Temperature control in the melting area facilitated heating zones was 20, 40,175,195 ° C. Behind the heating can (magazine: »Kunststoffe«, 1957, p. 436). zone IV was a perforated disc with a 3 mm hole diameter Since high-molecular polyolefins, especially high-knife built in, what the tape tool with Molecular polyethylene connected to low molecular weight with a nozzle size of 70 x 2 mm, much better properties, e.g. B. higher mechanical 65 The output was at a speed of having niche values, better fillability, etc., was 20 rpm. 8 kg / hour and at a speed of it is desirable to give this a wide application range of 34 rpm. 18 kg / hour opportunity to provide. The extruded material was melted well.