DD276594A3 - PROCESS FOR PROCESSING THERMOPLASTIC ABRASION - Google Patents

Abstract

The invention relates to a process for the processing of dust and filamentous thermoplastic abrasion, in particular from the pneumatic conveying of low-density polyethylene, by the abrasion from a Abriebbehaelter (1) is conveyed, which consists of three vertical and a 15 to 30 adjustable wall , Whose entire, open Bodenflaeche with three parallel discharge screws (2) is supported. The discharge screws promote abrasion to a dosing screw (3) which is offset by 90 °, lying deeper in the level, and from there the abrasion reaches via a suction conveyor (4) with blower (5) and cyclone (6), together with a constant amount of a polyethylene. Granule partial flow via a metering funnel (7) with metering screw into the plastic processing machine, preferably a twin-screw extruder. The discharge screws have a rising in Foerderrichtung gear depth and their speed is controlled by the armature current of the plastic processing machine. The speed of the dosing screw is 3 to 4 times greater than that of the discharge screws. The method allows the processing of different abrasion and also the use of non-standard products for the granular partial flow.

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a process for the processing of thread-like or dust-like thermoplastic abrasion obtained in the pneumatic conveying of thermoplastics, in particular polyethylene of low density.

Characteristic of the known state of the art

In the pneumatic conveying of thermoplastics, in particular low-density polyethylene, abrasion is caused by the wall joints occurring during the conveyance of the air. This abrasion can be in the form of filamentary or dusty abrasion in the conveyed product and can be very troublesome in subsequent operations. In the pneumatic demand of polyethylene granules falls pulvorförmor Abriob in which contains about 10 to 15% Abriebfäden 1 to 5cm in length.

This abrasion either remains in the product, which in the case of polyethylene (cable production, injection molding, film blowing) leads to interruptions in the production (clogging of filters, dosing lines, etc.) or remains in the exhaust air, which leads to environmental pollution. When depositing the abrasion in Schworkraft- or FlichkrafUibscheidern o. Ä., Z. B. to DE-OS 3330733, falls on a product that poses great problems in the subsequent Kompaktiorung or further processing.

A collection or reclamation of this abrasion is extremely problematic because it vorfgt on the one hand only about an extremely low bulk density (about 50kg / m ³ ) and is uneven and on the other bridging ("bridging") tends, so that dosiorto supply dos stockpiled Polyethylon abrasion is excluded to oinnr conveyor.

A processing dos polythene abrasion analogous dor of polyethylene low-density granules odor dor of polyethylene holier density powder and the return of Folionabfällen, as in dor DE-OS '"523242 boschriobon, is also not possible due to the different grain structures.

There are thus no ancestors for the processing of dust or filamentary Abriob, dor in the pneumatic conveying of polyethylene nioderor Dichto obtained bokannt. Bokannt are only ancestors for the carrying out and promotion of Schworflioßondon Gütorn, but in succession wochsolndon conditions of Abriobs are not transferable.

To avoid dor bridging boi bulk materials, dio for bridging noigon, according to DE-OS 2752406 vorgoschlagon, means for applying oinor shear force on the bulk material along a direction perpendicular to the direction of flow verlaufondon axis ohno noticeable Vordichton dos bulk material. Dioso's ancestors, boi dom with in the Bohä'ter lying vibration device is goarboitot, leads when using Polyothylon Abriob abor to obstruction and Untorbrochiingon in (lon Ausflußoffnungen.

Bunkor discharge device for in bunker golagorto debris wordon e.g. in DE-AS 2127570, DE-OS 2748007, DEOS 2757527 or DDPS 147348 boschriobon. Boi (nasty Voffahron wordon below dos Bunkorbodons different trained as augers Fördorolomonto with variable depending on the bolt Drohzahländorungon dor Rührarmo (DE-AS 2127570), back and backbowogiichon Fördorolomonton quor to Fördorrichtiing angoordnoton, voizugswoiso in cross-section koilförmigon sprouts (DD-PS 1 -17348) or Vorlagerbaron Stützkörporn (DE-OS 2757527) proposed.

DD-PS 2842471 describes a lock »for emptying brw removal and compression of bulk material from containers, bunkers and the like., In which a rotatable in a pipe and driven by a motor auger is arranged. When using these tools, although an improvement of the discharge from bunkers can be achieved, but when using polyethylene abrasion, the discharge remains irregular and so low that no secure further processing is possible. Dosing devices and devices for filling into processing machines for heavy flowing goods are also known.

Thus, according to DD-PS 147056 a metering device for powdery, crystalline or granulated solids in processing machines and apparatus proposed which consists of a conical or cylindrical Beh / Mter with a conical transition and a going through the container shaft with a arranged at the lower end metering screw , wherein the metering screw, the good side conveying and loosening elements, conveying rods, crusher pins and via a shaft connected to a ßegasungfimpulssystem Rührnrme are arranged upstream, is arranged in a coolable metering shaft. DD-PS 86493 describes an apparatus for evacuating and filling of powdery, grießiformon ader similar materials in evacuated processing machines, in particular extruder having a stopcock inlet in the upper part and in the lower vacuum-tight to be connected to the processing machine outlet and a ATschluß for a Vacuum pump and a level indicator has, according to the invention, the device consists of a single container in the Gutzuführungsleitung a valve is arranged, and with the interior of a l> e ^: minimum filling of the container, the valve-opening level indicator and a at a maximum pressure in the container the valve closing pressure-sensitive switch is connected.

DD-PS 230821 describes a feeding device for extruders with Pfa tungsmaterial low bulk density, with a feed hopper with Dosiorzylinder in which on the shaft of a metering screw a Verdichtunjissclinecke ax'al is slidably mounted against a compression spring.

At i'o. As a result of the axial force, the compacting screw is displaced against the compression spring so that an existing outflow slot between the screw and the funnel wall increases to a backflow gap, thereby increasing the conveying efficiency of the compressor screw such that the delivery volumes of the compressor screw and the screw conveyor However, these devices fail when using polyethylene abrasion due to the extremely low bulk density and the inconsistency of dust and fader-like Abrieb.

It is not possible to use commercially available processing machines directly on the collecting container of the pneumatic conveying device for continuous processing, since the seizure (about 0.1 to 0.2% (mass of the conveyed product) is very low due to the known danger of explosion For this reason, the abrasion must be collected and stored separately, and is due to the bridge formation so far from dormant containers not continuously discharged.

Object of the invention

The aim of the invention is to work up the resulting in the pneumatic conveying of thermoplastics, in particular of low density polyethylene, filamentous or dusty abrasion undzui production of films u.a. to </ valued.

Explains the nature of the invention

It was therefore the task to work up in the pneumatic promotion of low density polyethylene anfuliondon dust and filamentary abrasion so that over a longer period a consistent dosing accuracy is ensured in commercial Plastverarbeitungsmaschincn.

The object is achieved by a Vcifahren for processing thermopliistischem dust and thread-like abrasion obtained in the pneumatic conveying low density polyethylene by the abrasion from a Abriebbchältor (1) with discharge screw !! (2) being transported to a metering screw with homogenizing elements (3) and by suction (4) with blower (5) and cyclone (6), together with a constant flow rate of a polyothylene granulate toiletry at a ratio of attrition to Granules of 0.8 to 1.2 to 1, via a metering hopper (7) of a Plastverarbeitungsmo.-xhina (8) is supplied.

The Auri buckskin (Ij consists of three vertical walls and a wall which varies in angle from 15 to 30 degrees, and its open Rodon surface is supported by three parallol discharge screws (2), which are separated into three equal segments with a narrowing The speed is graded from 1 to 1.2 to 1.5 to 1 to 1.5 to 2.5, and its rotational speed is governed by (ion anko the plastic pre-mixing machine Dio dosing screw) (3) is lower in level and 90 degrees Prodcuts to the discharge screw (2) Sio is at a constant speed, which is 3 to 4 times higher than the speed of the discharge screw ^ botriobon.

With the orifice-derived method, both gosammoltor, sorton-rich abrasion, and a mixture of attrition of different base polymoron with the gloichon or fronide base polymoron can be worked up by selective detection.

The added PolyothylonGrnnulat can be both the gloicho Grundpolymoro dos Abriobs, as well as Polymoros with obwoiehonden goomotrischun forms wio Untorkorn or Uccorn or not standardgorechtos, also pre-soiled product.

Wojther k.inn the / utjosot / to granules usualo processing aid onthalton.

By means of the application of orequipment and the addition of polyolefin granules, the formation of bridges of abrasion is avoided, constantly constant, and Mongo Abriob is provided, thus ensuring a uniform dosage of the plostarbovingiDtischino. The orfindungsgomäßoVorfahron also allows with goringom mechanical Aufwnnri ao processing of abrasion in conjunction: nit dm use not gordcht ir and also impaired Polymoro.

embodiments

The explanation will be made with reference to FIG. 1.

The collected in bags abrasion is given in monthly driving periods in the Abriebbehälter (1). The Abriebbehälter (1) is placed in the vicinity of a processing machine, outdoor, but separate from the processing machine, and consists of three vertical walls and a 15 to 30 'changeable wall whose open bottom surface with three parallel discharge screws (2) is supported in the conveying direction increasing gangway.

The speed of the discharge screws of the abrasive container (1) are controlled by the armature flow of the twin-screw extruder.

The abrasion is transported by the discharge screws to a 90 degree offset, deeper in the level dosing screw conveyor (3) and dosed by this in a Saugfoiderung (4) with blower (5) and cyclone (6). The constant speed of the dosing screw (3) is 3 to 4 times greater than the speed of the discharge screws (2).

From the cyclone (6), the abrasion in free fall falls into a hopper (7) equipped with a Harischaber dosing screw of a double-screw extruder. Parallel to the abrasion stream, a constant amount of a polyethylene granule partial stream is fed into the metering funnel.

example 1

An abrasion mixture consisting of

90% (mass) of the polyothylene types: density 0.920 g / cm ³ , melt index C, ³ g / 10 min and density 0.915 g / cm ³ , melt index

0.25 g / 10 min, - x 8% (mass) Attrition of the tubular reactor polyethylene grade: density 0.920 g / cm ³ , melt index 0.7 g / 10 min and

- 2% (Masso) Attrition of the tube reactor polyethylene grade: density 0.920 g / cm ³ , melt index 2.1 g / 10 min

was at a rotational speed of the three parallel order screws from 22 to 26 rpm and a metering screw speed of 80 rpm, in an amount of 310 to 340 kg / h with 300 kg / h of standard-compliant tubular reactor polyethylene of density 0.920 g / cm ³ and melt index 0, 35g / 10min on a commercial twin-screw extruder (screw speed 140Upm, armature current 420 to 470A) into a granulate, which then on a Folienblasoxtruder (screw diameter 90mm, effective screw length 3OD, Werkzeugdurchmesscr 25mm! With internal cooling to foil for self-supporting bags at a throughput of 240kg and h 23 m / min haul-off speed was used, and the discharge screws used were divided into 3 equal segments with an increasing travel depth of 1 to 1.2 to 1.5 in the direction of conveyance. The amount of abrasion of granules was 1.03 to 1.13 1.

Example 2

The procedure was analogous to Example 1. Instead of the standp-jfcerechten polyethylene grade 300kg / h of a Granulatgemischos consisting of start-up and by-product with deviations in granule size, the melt index (> 30%) and the permissible degree of contamination (Vg> 10) on a twin-screw extruder with melt filtration (Trcsso no. 32, BO, 82 to 0.16 TGL 27 876) at a screw speed of 140 rpm and an armature current of 400 to 450 A, into a granulate, which then on ainom blown extruder (Schneckenendurchmserser 90mm, effective SchnockonlängoSOD, tool diameter 550rnm) to shrink film (1 350mm χ 450mm χ 0.15mm) and a throughput of 260kg / h (withdrawal speed 7 m / min) was ve'blasen.

Example 3

An abrasion mixture consisting of

- 70% (mass) Attrition of tubular reactor polyothylone tortone: density 0.921 g / cm ³ , melt indox 2.1 g / 10 min and seal

0.916g / cm \ melt index 1.9g / 10min,

- 15% (mass) attrition of tubular reactor-polyothylo.Tsorto: density 0.923 g / cm³ ^J , melt index 0.8 g / 10 min and

- 15% (mass) attrition of tubular reactor polyethylene grades: density 0.916 g / cm ³ , melt index 1.8 g / 10 min, density 0.918 g / cm ³ ,

Melt index 7.2 g / 10 min, density 0.916 g / cm ³ , melt index 17.5 g / 10 min and seal 0.921 g / cm ³ , melt index 21.3 g / 10 min

was at a discharge screw raw number of 22 to 26 rpm and a dosing screw speed of 80 rpm, in an amount of 310 to 340kg / h with 350kg / h of a granular mixture of start-up batches with different granule size and high proportion of crosslinked and contaminated particles on a twin-screw extruder (screw speed 140 rpm, armature flow 400 to 440 A) with melt filtration (Trosse 32, TGL 27876) into a granulate, which is then added to a Folionblasoxtruder (Schnockendurchmosscr 90mm, effective length 30D, tool diameter 225mm) to oinor Folio 700mm χ 0.05mm for Einstollsäcko for Emballagen a throughput of 220kg / h and a discharge speed of 56g / min was blown. Boini Folionbluson was admixed with a lubricant and antiblock concentrate, so that in the folio oino concentration of 500ppm oleic acid and 800ppm of superdispersed silica was calculated. The oingosotzton discharge screw cones are in 3 equal segments with in stoigondor G mgtiofo of 1 to 1.5 to 2.5 oingo'.oilt.Dis Mongonian abrasion to granules was 0.83 to 0.97 / ui.

BeispleM

Hai oinor threat number of the discharge tube from 25pm and one speed dor dosing screw from 86pm were 330kg / h Abriob dor Polyothylongrundsorto dor Dichto 0.922g / cm ³ and dos Schmolzindoxos 0.3g / 10min with 32Okg / h of output polyethylons on oinom twin screw extruder (Schnukoiuirohzahl l40Upm, Ankorstrom 420 to 440A) to oinom * granulate vorarboitol, the Anschlioßond ouf oinem Folienblosooxtrudor (Schnockondurchmossor 90mm, wirko Schnockonlango 3OD, 225 mm Arbeitszeug'lurchmossor) with internal cooling to Folio for soltragtragonde Sncko at oinom throughput of 225kg / h vorblason was. Injected Schnockon-according to the embodiment of Boispiol 1. The ratio Abriob to granules botrug 1.03 to 1.

Claims (4)

1. A process for the processing of thermoplastic dust and filamentary abrasion obtained in the pneumatic conveying of low density polyethylene, characterized in that the abrasion from an abrasive container (1) with Austi agsschnecken (2) on a dosing with homogenizing elements (3) transported by a suction conveyor (4) with blower (5) and cyclone (6) together with a constant amount of polyethylene granules at a ratio of abrasion to granules of 0.8 to 1.2 to 1, via a metering hopper ( 7) is fed to a plastic processing machine (8). 2. Apparatus for processing thermoplastic abrasion, characterized in that the abrasive container (1) consists of three vertical walls and an angle of 15 to 30 degrees variable wall whose open bottom surface with three parallel discharge screws (2) is supported. 3. Apparatus according to claim 2, characterized in that the discharge screws (2) in the conveying direction into three equal segments with a ratio of the flight depth of 1 to 1.2 to 1.5 to 1 to 1.5 to 2.5 are divided and their speed is controlled by the armature current of the plastic processing machine (8). 4. Apparatus for processing thermoplastic abrasion, characterized in that the metering screw (3) in the lower level and offset by 90 degrees to the discharge screws (2) is mounted and it is at a constant speed, which is 3 to 4 higher than the speed of Discharge screw, is operated.