DE19744515A1 - Co-extruding polymers with differing processing temperatures - Google Patents

Abstract

The apparatus for coextruding polymers whose processing temperatures vary, consists of two or more extruders connected to a coextrusion head that is provided with heating, cooling and insulating zones. The coextrusion head (4) is provided with low temperature (11) and high temperature (12) flow channels that accept polymer melt flows from first (1) and second (2) extruders. Flow from these channels is conducted to a die/die holder combination (3) attached to the coextrusion head. In the die, the flows are combined and shaped as a coextrusion of desired form (6). The separate polymer flows (11,12) are combined only at the die front plate (13). Coextrusion head (4) consists of a manifold (10) that includes zones for cooling (20,21), heating (30,31) and insulating (40). The cooling zones are provided as semi-arcuate channels on either side of low temperature flow channel (11). The heating zones are similarly provided on either side of high temperature flow channel (12). The insulating zone is provided between adjacent cooling (20) and heating (30) channels. Cooling (22,23), heating (32,33) and insulating (41) zones are similarly provided in die/die holder (3).

Description

Extrusion devices for the production of endless profiles are always applicable when the materials to be formed, if necessary, can be made flowable by means of heating. The Extruding differs from the process engineering similar Chen injection molding in that parts are manufactured continuously can be. Typical products are semi-finished products such as Solid bars, pipes, hoses, sheets and other profiles, corrugated sheets, wire jackets, mesh nets as well as many Precast hollow parts.

When extruding thermoplastics, a pourable powder or granules are fed into the extruder, with stabilizers, lubricants and dyes or fillers offset and then by means of a screw to a pro promoted extrusion die, the materials compressed, degassed and with simultaneous mixing and kneading be homogenized. The homogeneous flowable mixture that Molding compound, is kept at a temperature or warmed, the lower limit of which is plasticized and thus the deformability of the material and its upper limit is determined by the decomposition of the material. In correspond accordingly, sheet-like semi-finished products are made by slot die with subsequent passing through a smoothing mill poses.

So-called extrusion is used to manufacture hollow bodies blow applied, in which in a first step of the Extruder made a piece of hose and in a two-part Tool is guided after the material has been inserted is closed, the protruding hose ends abge are squeezed and the cut edges are then welded become. Through a hollow needle compressed air is still hot and malleable tube section  blown, with which the hose expanded and to the cooled Tool wall is pressed where the plastic cools and stiffens. After opening the tool, the finished hollow body can be ejected.

Films made of thermoplastic materials are made using the so-called film blowing. In this case it is an extruder is followed by a blow head in which a formba rer plastic hose is generated by compressed air is inflated in a thin-walled film bag. When inflating solidifies the plastic mass. The foil bag can be continuous be pulled off and wound up.

The above-described primary form processes then prepare none Difficulties when processing only one plastic material shall be. It is also possible in principle by coextrusion different materials at one set temperature to process composite profiles that e.g. B. used for sealing purposes. In composite profiles can advantageously the properties of different Material components are combined in the manufactured piece. So long as the raw materials to be extruded together can be processed at the same temperature by molding, can thus the known extrusion processes without restriction be applied. However, this requirement is not always fulfilled, especially not if Materials to be processed are different Shaping temperatures require. This applies, for example, to the combination of rubber or rubber with other thermopla elastic elastomers (TPE) that can be combined in terms of Properties seems particularly desirable.

Among thermoplastic elastomers synthetic Polymers are understood to be (macromolecular substances) reversible at least twice to multiple times their out stretch length and a high tensile strength and a have good rebound resilience. Many synthetic ones  Thermoplastic materials have desirable properties like a high resistance to aggressive Ambient influences, color fastness and the like and can as processable raw materials with precisely defined or a adjustable properties are manufactured industrially. After is a part of some thermoplastics limited elasticity behavior, especially when changing the ambient temperature. Different elasticities in changing temperatures, however, limit the possible application strong.

Rubber is primarily the natural raw material Understand rubber-made material. The natural rubber in pure form is initially a plastic product, but that with longer storage due to crystallization and cross-linking of the linear macromolecules hardens and becomes brittle. To the Rubber the valuable properties of rubber, namely one Elasticity and resistance to atmospheric and chemical influences as well as against mechanical stress lend, it requires vulcanization, in which the rubber by heating and kneading in the presence of atmospheric oxygen a plastic shape is brought and then with Schwe fels and fillers such as carbon black and zinc oxide and the most diverse vulcanization aids and stabilizers sators is mixed. By pressing this mixture and heating zen to about 160 ° C to 180 ° C (hot vulcanization) Crosslinking of the elongated rubber molecules by welding rock bridges.

The above-described rubber made from natural rubber Similar are synthetic elastomers made by polymerization are produced from olefins or vinyl derivatives, for which the Copolymers of ethyl acrylate with acrylonitrile as well Combinations of ethylene with propylene and dicyclopentadiene (EPDM) belong. The EPDM, for example, has one particularly high elasticity and elastic deformability as well as UV resistance, which the use z. B. for you  make profiles particularly suitable. The above Properties are largely independent of temperature.

A disadvantage of synthetic and synthetic types of rubber are the limited coloring and the temporary Appearance of optical defects (efflorescence etc.) and the Odor formation up to possible health problems impairments by outgassing volatile components longer periods. With the connection of different basic sub Punching in a product can have positive properties combined or the negative properties are compensated. The common extrusion of different materials Production of a composite material in one step However, according to the prior art, the different Processing conditions of the materials. So at for example to avoid premature vulcanization or also a beginning networking in the flow channels of the Extrusion head the rubber material if possible at temperatu extruded from 100 ° C to 120 ° C. On the other hand, must many thermoplastic materials for extrusion at Temperatu ren above the melting point, d. H. at 200 ° C to 250 ° C be kept flowable.

It is therefore an object of the present invention to provide a method and to create a device with which it is possible to under different materials at different temperatures are deformable, can be extruded together to a ver to produce bundle material.

This task is procedurally followed by the measures Claim 1 solved, according to the invention the different Materials via separate and separately temperature-controlled and channels thermally insulated from each other in an extrusion plant stuff are fed in which the different Materials, preferably under pressure, brought together and be extruded. Depending on the required temperature Maintaining fluidity will be the under  different channels heated and / or cooled, so that each one individual starting material individually at the desired tempera is held. In other words, the temperature zones of the individual channels are separated in the feed area. Just a moment Before reaching the profile tool, the material components merged.

Further embodiments of the invention are in the subclaims 2 to 5 described.

It is known from the prior art to have composite bodies elastic plastic material with support bodies, e.g. B. biegsa to produce steel inserts. This can, for example, in Within the scope of the method according to the invention occur in that the extrusion body over at least one other preference wise temperature-insulated duct solids are fed, which extruded together with the merged materials become. Such support bodies can, for example, steel inserts be that of the flowable coextruded materials be injected. After exiting the extrusion die can then - depending on the bending ability - the steel inserts be plastically deformed, for example for corner profiles Manufacture sheet metal edge parts. Supporting bodies concerned can also be prefabricated plastic parts, which accordingly desired mechanical properties in contrast to the bend flaccid material with which they are encapsulated.

Alternatively, it is also possible with the present invention the support body only together by appropriate molding tools Original in one operation with the composite material. Here at is a powder or granular starting material in mixed accordingly, to form a flowable substance homogenized and compacted, which then together with the rest Substances either shortly before reaching coextrusion used profiling tool already in hardened Form fed and overmolded or still in flowable Form via profiled channels the profiling  Extrusion tool is reached and extruded together. This has the particular advantage that the previously used steel deposits, their separate production and their intermittent feed tion can be omitted, since both the desired composite let the body and the support body co-extrude.

Preferably rubber (made from natural and syn synthetic rubber) and rubber-like elastic art fabrics with any thermoplastic elastomers, possibly com trimmed with reinforcing inserts, co-extruded.

The material-coordinated temperature control of the separate channels, from which have at least two depending on the material combination, is preferably done by electric heaters, in particular Resistance heating, or by washing around with liquid substance like thermal oil. In a corresponding manner, the feed ka channels by rinsing with coolant, in the simplest Case with water, be cooled. This includes that use uniform extrusion head made of a metal material det is in which corresponding channels are arranged. Should e.g. B. one of the channels heated to a temperature of 250 ° C. be, e.g. B. via resistance heating plug inserted in holes tronen, and the second channel should have a temperature of 120 ° C received, so the heat conduction and radiation of the existing tempe generated by the resistance cartridges rature in the second channel can be reduced by the fact that the fend channel with a cooling liquid and thermal is separated.

2 or more different materials can be co-extruded become; foaming can also be carried out - with or without a support body bare and non-foamable rubbers can be used.

The task is device-related through the extrusion Direction solved according to claim 8, the invention thereby is characterized in that at least two separate, each connected to a separate extruder, separate tem  Perchable channels open into an extrusion tool, preferably wise, seen in the direction of flow, immediately in front of a profile disc.

Further developments of this extrusion device are in the Claims 7 to 10 described.

The structure and the advantages of the extrusion device is based on referred to the above statements. The flow channels best hen preferably each separately from one in the housing part of a coextrusion head and a hole in the outer jacket of an inner part of the sleeve designed as a sleeve Head incorporated inner channel. In the immediate vicinity of the Inner channels are both in the housing part and in the quill Bores for holding heating elements or for guiding Liquid media introduced for heating or cooling. For thermi separation of the different temperature zones which can also have a number in the quill between the Cavities located in temperature zones are present through which the thermal resistance between the different temperatures Door zones increased and the heat flow and temperature compensation be reduced.

An embodiment of the invention is in the drawings shown. Show it:

Fig. 1 shows an extrusion device according to the invention in a schematic representation and

Fig. 2 is a sectional view of an extrusion head with extrusion tool.

Two (or more) extruders 1 and 2 , known in principle according to the prior art, are used to process different starting materials which are co-extruded into a composite material. The flowable, homogenized and compacted materials pass through channels 11 and 12 of an extrusion head 4 into a common central part 10 , which is connected to a schematically illustrated extrusion tool 3 . The channels 11 and 12 are only brought together immediately before the profiling tool 13 in such a way that the different starting materials are pressed together by the tool 13 and processed into an extruded profile 6 . A resistance heating element 9 , which maintains the flowability of the material stream coming from the extruder 2 , is used to temper the channel 12 in the central part 10 . On the other hand, the much lower temperature is set in channel 11 by rinsing a liquid temperature chamber 7 with the appropriate coolant. An insulation chamber consisting of a bore 8 also inhibits heat conduction in the direction of the channel 11 . In this way, e.g. B. maintain a temperature of 250 ° C in the feed channel 12 and a temperature of 120 ° C in the channel 11 who the. In addition, reinforcing members 5 are introduced via a not-shown bore in such a manner into the extrusion head, that these are compared with the material flow coex trudiert or encapsulated from channels 11 and 12. FIG. Insofar as the reinforcement insert 5 is a solid which can be produced by extrusion, a further temperature-controlled channel, not shown, can be provided in a corresponding manner, via which the flowable material of the reinforcement insert is fed to the extrusi on head 4 . Depending on the material and processing temperature as well as the desired connection, the hardening of the solid (reinforcement insert) can take place shortly before reaching the tool head or only in the tool head, the latter with the aim of ensuring an intimate connection of the reinforcement insert with the coextruded material streams from channels 11 and 12 . The channel guide and any nozzles, matrices or other profiling disks of the extrusion tool 3 are adapted to the composite material to be produced and the number of channels 11 , 12 and further channels. The temperature guidance of the channels 11 , 12 and other channels results from the processing temperatures of the starting materials used.

Claims (12)

1. A process for producing an endlessly extruded profile strand by coextrusion of different materials, the extrusion temperatures of which differ from one another, characterized in that the different materials are fed to an extrusion tool ( 3 ) via separate channels ( 11 , 12 ) which are each separately temperature-controllable and thermally insulated from one another , there, preferably under pressure, brought together and extruded. 2. The method according to claim 1, characterized in that in addition via at least one further, preferably temperature-insulated channel solid body ( 5 ) the extrusion tool ( 3 ) are fed, which are extruded together with the materials brought together. 3. The method according to claim 1, characterized in that flowable plastics are supplied via a further temperature-controlled channel, which harden to a support body ( 5 ) before or when reaching the extrusion tool ( 3 ) and extruded together with the other materials will. 4. The method according to claim 1 to 3, characterized in that thermoplastic elastomers (TPE) and more natural Rubber (rubber) can be co-extruded. 5. The method according to any one of claims 1 to 4, characterized in that the separate channels ( 11 , 12 ) by means of electrical heaters ( 9 ), preferably resistance heating tongues or by rinsing with liquid substances, preferably thermal oil, are heated. 6. The method according to any one of claims 1 to 5, characterized characterized that more than 2 different materials be co-extruded.   7. The method according to any one of claims 1 to 6, characterized characterized in that foamable rubbers in Used in combination with non-foamable rubbers become. 8. extrusion device for producing a composite material from different materials, the extrusion temperatures of which differ from one another, characterized in that at least two separate, each with separate extruders ( 1 , 2 ) connected, separately temperature-controlled channels ( 11 , 12 ) in an extrusion tool ( 3 ) open, preferably - seen in the direction of flow - immediately in front of a profile disc ( 13 ). 9. Extrusion device according to claim 8, characterized in that at least one further, preferably temperature-insulated channel for supplying solids ( 5 ) is provided, which also opens into the extrusion tool ( 3 ). 10. Extrusion device according to claim 8 or 9, characterized in that for the temperature control of the channels ( 11 , 12 ) heating and / or cooling devices ( 9 ) or cavities ( 8 ) are provided for temperature insulation. 11. Extrusion device according to claim 10, characterized in that the heating devices consist of electrical heating elements, preferably resistance heating elements ( 9 ). 12. Extrusion device according to claim 10, characterized in that the heating and / or cooling devices consist of channels ( 7 ) which are flushable by means of heating and / or cooling liquids.