FI90323B - Apparatus for producing an electrically conductive polymer product - Google Patents

Description

90 323

The invention relates to a device for the production of an electrically conductive polymer product by doping a conductive polymer, the device having a cylindrical mixing housing, into which a material to be mixed and a monomer of the matrix polymer and a conductive polymer to be mixed is placed. the mixing.

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Plastics and other polymers do not conduct electricity per se, but can be made electrically conductive for a variety of applications. Electrically conductive polymers can be prepared from organic polymers with long chains of conjugated double bonds. The amount of silicon-15 electrons in the double bonds can be affected by the addition of certain dopants (dopants) to the polymer, which are either electron accepting or donating. Thus, gaps, or extra electrons, are created in the polymer chain, which allow an electric current to flow along the conjugated chain. The electrical conductivity of the polymers can be adjusted depending on the dopant content to cover almost the entire conductivity range from insulators to metals. Such electrically conductive polymers have many interesting applications, e.g., EMI applications and ESD applications (see pages 6 and 7).

Polythiophene is one of the polymers that can be electrically activated as described above. Polythiophene can be prepared, for example, using Ziegler-type catalysts and acid initiators.

The applicability of electrically active polymers depends on e.g. their stability properties. Polythiophene in reduced pure form is very stable under various conditions such as air, humidity, vacuum and high temperatures. In contrast, the stability of the electrically conductive polythiophene under different conditions depends on the dopant anion used. The polythiophene complexes previously disclosed are more or less unstable and thus questionable for many applications. According to an earlier patent application of the applicant, "Electrically conductive polythiophene and a process for its preparation 2 90323 and its use" (FI-852883), a more stable electrically conductive polythiophene polymer has been prepared by doping or treating it with FeCl 3.

The conductive polymeric and organic conductors are generally Liu-5 non-lubricating, cannot be melted or shaped, and are in some cases unstable against oxygen, moisture, and high temperatures, which is why doping at high temperatures has not been successful in the past. Until now, it has therefore not been possible to thermoplastically treat or modify the conducting polymers in any way. 10 There have been reports of the meltability of some individual conducting polymers, but their conductivity has been very poor. After doping, the polymer is generally insoluble and can no longer be modified, which is why doping has traditionally been performed after processing of the polymer.

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Thus, it is known from the prior art that the doping of the polymers takes place after the treatment, i.e. the formation of the product, e.g. in the above-mentioned manner with FeCl3. Such a method becomes very expensive due to the special devices for doping and, in addition, it is impractical and environmentally unfriendly because toxic volatile gases are released into the environment.

In order to solve this problem, attempts have also been made to develop special polymerization methods and to form mixtures of conductive polymers and other polymers which could be modified after doping. However, the conductivity has generally been too low.

With regard to the state of the art related to the present invention, reference is made to EP Patent Application No. 0 168 620, the aim of which is to obtain a stable dispersion of the conductive polymer 30 in a thermoplastic polymer which can be shaped while maintaining optimal conductivity. The aim of this publication is also the possibility of stabilization after dispersion. In this EP, the polymer is mixed (dispersed or dissolved) in the molten Lila with the homopolymer until a homogeneous mass is obtained, after which the solvent is removed. The matrix polymer is stated to be polyether, polyester, polyvinylidene chloride, poly-90903 amide, etc. The doping according to the publication takes place in solution or by sonication. Additives are also added to improve workability.

5 The applicant's earlier FI application 901632 discloses for the first time a method for manufacturing an electrically conductive polymer product by doping, in which the doping takes place in connection with or even before the processing of the polymer. The purpose of FI application 901632 is to provide a method for doping a conductive polymer, in which the properties of the conductive polymer can be modified as desired and which is stable.

The object of the present invention is to provide a device in which the above-mentioned objects are realized even better and to further develop the invention of FI application 901632.

15 In this application, the term "conductive polymer" is also used for a doped polymer, although it is not yet electrically conductive prior to doping.

To achieve the above objects, the device according to the invention is mainly characterized in that it has a first body with a mixing housing and a second body with a mixing head and that the mixing head and the mixing head form a clearance in which mixing mainly takes place and in a closable mold. leading channel.

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Preferred embodiments of the invention have the features of the subclaims.

The invention utilizes the realization of FI application 901632 that doping can be performed by adding a doping agent to the conducting polymer while it is in the molten state and the doping is timed to occur during processing. In FI application 901632, doping was performed during processing of the product, e.g. in connection with injection molding, in which case the doping agent was added to the extruder before pressing into the mold.

The present invention provides a novel device for doping a conductive polymer in the molten state. According to the invention, the dopant can be introduced into the melt mixture either mixed with the conductive polymer, mixed with the matrix plastic, or the dopant can be added directly to the conductive polymer 5 or to the melt formed by the conductive polymer and the matrix plastic. In this case, the mixing of the dopant with the plastic takes place before the product is compressed, whereby the doping begins during melt mixing and continues during and after the shaping of the product.

The oxidizing or reducing dopant may be either a gas (eg iodine vapor), a liquid (eg liquid sulphonic acid) or a solid (eg sulphonic acid with a suitable melting point).

The polymer used can be any melt processable dopable polymer, e.g. poly (3-octylthiophene), and any polymer to be processed as the matrix material.

The dopant is added to the conductive polymer or mixture of conductive polymer and matrix polymer before, during or after melting.

The invention can be used to make any polymer with any electrical conductivity.

An embodiment of the invention will now be described with reference to the figures of the accompanying drawing. This is not intended to limit the invention to the details of the figures.

Figure 1 shows a sectional view of a device according to the invention when the parts of the device 30 are separated.

Figure 2 shows the melting and first mixing steps.

Figure 3 shows the second mixing step and the machining step.

Figure 4 shows the test piece removal step.

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Figure 1 shows the mixing device 10 when its main parts, the first body 1 and the movable body 2, are separated. The first body 1 has a mixing housing 11, which may have projections to enhance mixing. The movable body 2 has a movable agitator head 12 which can rotate 5 in the agitator housing 11. The size of the agitator housing 11 varies as the agitator head 12 moves axially in the agitator housing 11.

An embodiment of the device according to the invention also has heating 16 and, if necessary, cooling. The movable rotating agitator head 12 is sealed to the movable body 10 by means of a piston rod sealing ring (23a, 23b).

It can be seen from Figure 1 that the channel 24 leads from the mixing housing 11 to the mold half 25 in the first body 1 of the device 10 with the mold housing 26. The bodies 1 and 2 can be placed opposite each other, the dividing plane 15 closing so that the mixing head 12 rotates in the mixing housing 11 and mold half 25 the mold half 27 in the body 1 and the body 2 form a mold. The mold can be cooled. If desired, the channel 24 can be closed or opened by means of a movable piston 28, which in Fig. 1 is in the closed position.

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The functions of the mixing device according to the invention will be apparent from the accompanying drawings 2-4.

Each of the main parts 1 and 2 of the mixing device 10 has heating devices for heating and defrosting the substance to be mixed, which are most preferably electric resistors 16. Accordingly, the device may have cooling, preferably piping for the circulation of the coolant.

The raw material 18 to be mixed is added to the mixing device 10 in a mixer-30. Thus, in the invention, the substance to be mixed is a conductive polymer or a mixture of a conductive polymer and a matrix polymer and often already at this stage a dopant.

Such an embodiment is possible in which the substances 18 or parts thereof 35 are added to the device 10 through the opening later, whereby the parts 1 and 2 are already facing each other. The substance to be mixed 18 is most preferably added as solids, e.g. granules, which are melted by means of heating devices in the mixing device 10, preferably e.g. electric resistors 16. If there is no opening in the mixing space, the substance to be mixed 18 (conductive polymer) and the dopant or polymer blend and dopant are added to the mixing space 5 11 with parts 2 and 1 being separated, as described above.

In the melting and first mixing step shown in Fig. 2, the substance to be mixed 18, which is thus a conducting polymer or a mixture of conductive polymer and matrix polymer and preferably at this stage already a doop-10 release agent, is entirely in the mixing space 11. Mixing is performed by rotating the mixing piston 12. The melting of the substances to be melted and mixed 18 by means of electric resistors 16 takes place at this stage. The dividing plane is then closed and the movable piston 28 is still in the closed position. The substance to be mixed passes a short distance through the channel 24, but not 15 past the moving piston 28.

Figure 3 shows a second mixing step and a machining step in which in the former the material to be mixed 18 is pressed along the channel 24 into the mold 25. This is done by pushing the mixing piston 12 into the mixing space 11 and 20 by opening the movable piston 28.

Figure 4 shows the cooling step and the test piece removal step. Once the mixing steps shown in Figures 2 and 3 have been completed, the mixed product 19 can be cooled by introducing a coolant 25 into the cooling channel 17. The blended product 19 in the mold is formed in the final step.

In this case, the mixed product 19 can be cooled under pressure and thus the separation of gases in the plastic can be prevented.

The cooled, mixed product 19 is removed from the shaping treatment after the mixing device 10 by separating the main parts of the mixing device 10, the body 1 and the body 2.

The mixing device 10 is preferably associated with a cooling device, e.g., channels surrounding the mixing space 11 for the circulation of coolant. The addition of Edul-35 is to use water as the coolant.

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The advantages of the invention are that it has a wide range of applications, as it can be used for the production of conductive materials, such as EMI (computer monitor) (EMI - electromagnetic interference) or ESD (antistatic mat) applications, the composition being, for example, 1 ) PP + POT (polypropylene + polyoctylthiophene), 2) hard PVC + POT (polyvinyl chloride + polyoctylthiophene), 3) soft PVC + POT, (polyvinyl chloride + polyoctylthiophene), 10 4) PS + POT (polystyrene + polyoctylthiophene), 5) PE + POT (polyethylene + polyoctylthiophene), 6) EVA + POT (ethylene vinyl acetate + polyoctylthiophene).

7) ABS + PVC + POT (Acrylonitrile butadiene styrene + polyvinyl chloride + polyoctylthiophene) 15

The following are claims which, within the scope of the inventive idea, may vary the details of the invention.

Claims (8)

An apparatus for producing an electrically conductive polymer product by doping the conductive polymer, said device (10) having a cylindrical mixing space (11) in which to place the blank (18) son is to be blended, which is the conducting polymer or a mixture of the conductive polymer. and a piston-shaped mixing head (12), characterized in that it has a first body (1), where the mixing space (11) is located, and a second body (2), where the mixing head (12) is present and that the mixing space and the mixing head limits a gap where the mixing to main parts occurs and a channel (24) leading to a closable mold. Device according to claim 1, characterized in that the mixing head (12) rotates about its axis. 3. Device according to claim 1 or 2, characterized in that the mixing head (12) can move back and forth in the direction of its axis, the mixing being effected by the action of pumping. Device according to any one of claims 1-3, characterized in that there are projections on the mixing head (12) or in the mixing space (11) to effect the mixing. 25 Device according to any one of claims 1-4, characterized in that in the first body (1) of the device there is a mold half (25) and in the second body (2) a second mold half (27) which together forms a mold for product. 30 Apparatus according to any one of claims 1-5, characterized in that the device has means for heating and melting the blank. Device according to any one of claims 1-6, characterized in that it has means (17) for cooling the mold. u 90323 Device according to any one of claims 1-7, characterized in that it has a movable piston (28) which closes to the passage to the mold and which can be opened. 5