NL9000321A - Intrinsically conductive moulding cpd. prepn. - comprising in-situ polymerisation of monomers in presence of matrix polymer and catalyst, pref. halogen salt and transition metal - Google Patents

Abstract

Prepn. of an intrinsically conductive moulding cpd. obtd. by in situ polymerisation of monomers, which form an intrinsically conductive polymer after polymerisation, in the presence of a matrix polymer, and a catalyst. The matrix polymer is dissolved in an essentially solvent free monomer, after which the soln. is brought into the desired form and the monomers polymerised in situ in the presence of the catalyst. Also claimed is a fibre, film or moulding cpd. obtd. by this process. Pref. the quantity of matrix polymer relative to the monomer is at most 95 wt.%. The polymerisation of the monomers is followed by a doping step. From the soln. of monomer, matrix polymer and catalyst a filament of at least 5 mm is spun with a drawing rate of 500 mm/min.. The matrix polymer has a mol. wt. at least 100,000 g/mole. and is substantially unbranched. Pref. the catalyst consists of a salt of a halogen and a transition metal. The monomer phase comprises pyrrole, thiophene, benzene, aniline, furan, and/or derivs. thereof.

Description

Inventors: Ronald M.A.M. Schellekens in Maastricht Hans K. van Dijk in Geleen Markus J.H. Bulters in Sittard

INTRINSICALLY CONDUCTIVE MOLD

The invention relates to a process for the preparation of an intrinsically conductive molding compound obtained by in situ polymerization of monomers which form an intrinsically conductive polymer after polymerization, in the presence of a matrix polymer and a catalyst.

Such a method is known from EP-A-314311. The method of this patent discloses dissolving a thermoplastic matrix polymer in a solvent, then bringing the solution into a desired shape and gelling the solution. Acetylene gas and a catalyst solution are then added. The acetylene is polymerized to polyacetylene, after which an intrinsically conductive molding compound is obtained after doping. The molding compound still has to undergo several operations to remove, for example, the solvent and the catalyst.

A disadvantage of the method as described in EP-A-314311 is the use of large amounts of solvent for the matrix polymer. The solvent, for example decalin, must be removed from the final molding compound with an additional operation. The solvent therefore has an adverse effect on the speed of the manufacturing process.

The object of the invention is to provide a process for the preparation of an intrinsically conductive molding compound which has good conducting properties in combination with an excellent dimensional stability.

The process according to the invention is characterized in that the matrix polymer is dissolved in an essentially pure momomer mixture, after which the resulting mixture is brought into the desired form and the monomers are polymerized in situ in the presence of a catalyst.

It has been found that the method according to the invention provides a molding compound which has very good conductive properties. The method according to the invention is eminently suitable for the continuous production of fibers and films.

It has been found that, with the method of the invention, molding compositions exhibit increased stretchability handling during molding. Such molding compositions are preferably further stretched, which may lead to improved mechanical and conductive properties and improved dimensional stability. The omission of the solvent leads to a reduction in the number of processing steps required.

By an essentially pure monomer mixture is meant a liquid mixture in which more than 90% by weight of monomers and / or oligomers are present, preferably more than 95% by weight, in particular more than 98% by weight.

Up to 60% by weight of additives may be added to the pure monomer mixture, for example, flame retardants or flame retardants, pigments, antioxidants, stabilizers and the like.

The method according to the invention is further characterized in that (a) a matrix polymer is dissolved in the monomer mixture, the amount of matrix polymer being at most 95% by weight, based on the monomer mixture; (b) after which the resulting mixture is brought into the desired shape; (c) wherein the monomers are polymerized in the presence of a catalyst consisting of a salt of a halogen and a transition metal; (d) optionally followed by a doping step, after which an intrinsically conductive molding compound is obtained.

The invention is particularly effective when the monomers forming an intrinsically conductive polymer are selected from the group: pyrrole, thiophene, benzene, furan, aniline and derivatives of said monomers. More particularly pyrrole and / or thiophene. Pyrrole and thiophene are already liquid as monomers at room temperature, which considerably simplifies processing with the method according to the invention.

The process of the invention is not limited to the use of monomer mixtures of one monomer, but combinations of monomers in the mixture are also possible. For example, combinations of substituted pyrrole and pyrrole are active. Preferably, the monomer mixture contains at least one heterocyclic aromatic.

As a result, molding compositions can be manufactured with the method according to the invention, the conductivity of which is at least 0.1 S / cm. "

If desired, up to 60% by weight of polymers other than the matrix polymer, ionomers and / or fillers may be added to the monomer mixture. The addition can take place before, during or after dissolving the matrix polymer in the monomer mixture. Polymers to be added are, for example, elastomers; ionomers to be added are, for example, copolymers of ethylene and methacrylic acid. Preferably such ionomers are added if a foil is the desired end product. Examples of fillers to be added are talc, kaolin, wollastonite, glass.

In principle, any polymer which is soluble in the monomer mixture can be chosen as the matrix polymer. The matrix polymer is necessary to effect shaping of an intrinsically conductive molding material. The coherence of the molding compound is also greatly improved. Examples are homo- and copolymers of: poly (vinyl alcohol); polyethylene, for example UHMWPE (ultra high molecular weight polyethylene); poly (ethylene oxide); poly (vinyl acetate); polystyrene and the like. The molecular weight depends on the selected matrix polymer and the application, but is preferably at least 100,000 (M). In the

W.

in particular at least 500,000, more in particular at least 1,000,000 g / mol.

The amount of matrix polymer added is preferably less than the amount of monomers. Preferably, the amount of matrix polymer in wt. parts less than 40% of the amount of monomers. In particular less than 25%. Higher concentrations of matrix polymer can result in lower conductivity of the final molding compound.

An important parameter for the optimal concentration of the matrix polymer is the molecular weight (M) and the degree of branching of the matrix polymer. Is

W.

the matrix polymer high molecular (e.g.> 1,000 kg / mol) and linear, concentrations of 0.2% by weight will suffice. If the matrix polymer is high molecular but branched, the minimum concentration will be more than 2% by weight. Preferably, a high molecular, mainly unbranched matrix polymer is added.

The amount of matrix polymer partly depends on the desired end product. If a molding compound with a free surface during processing is desired, the amount of matrix polymer to be added will depend on the processability of the solution. Examples of such molding compositions are fibers, tapes, foils, films, etc. The workability of the resulting mixture after adding a catalyst should be sufficient to produce a wire of at least 5 mm at a drawing speed of 500 mm / min. Preferably 7 mm, more in particular 10 mm. The determination of workability in such a manner is described in Tammann G., Tampke R., Z. An. you. Allg. Chemistry, Bd. 162 (1927) pp. 1-16.

The method according to the invention lends itself perfectly to manufacture a fiber continuously. For this purpose, a solution of the matrix polymer in the monomer mixture and a catalyst are combined under very short mixing (<5 seconds), after which a fiber is continuously spun from the mixture. Preferably, minimal quantities of matrix polymer are used in the manufacture of a highly conductive fiber. More specifically, less than 15 wt. divide by 100 wt. parts monomer.

The polymerization catalyst to be added is preferably a salt consisting of a transition metal, in particular Fe, Co, Ru, Cu or Sn and a halogen. An iron (III) chloride solution in water or tin (IV) chloride is particularly effective. If a catalyst solution is used, an amount of matrix polymer can optionally be mixed with the catalyst solution before adding the catalyst solution to increase the miscibility of the catalyst solution with the monomer mixture.

The catalyst is preferably added * during or after shaping the mixture. However, it is also possible to block the catalyst so that a latent catalyst is obtained, which can be added before molding and becomes active after deblocking. The catalyst is preferably added in excess.

After formation of the final product and polymerization of the monomer mixture, if desired, catalyst residues can be removed by extraction. It is also possible to deform the final product mechanically before or after the extraction, for example stretching, which can lead to improved mechanical and conductive properties.

Depending on the intrinsically conductive polymer obtained, a further doping step can be added to the method according to the invention after polymerization. The doping can be both oxidative and reductive, using known doping reagents and techniques.

The conductivity of a formed end product can be determined with a so-called four-point measurement. This method is fully described in EP-A-0314311 and in H.H. wieder Laboratory Notes on Electrical and Galvanomagnetic Measurements, Elsevier, New York, 1979.

Using this method the specific conductivity is measured: σ - L / A * 1 / R, where σ = specific conductivity, S / cm; L * distance between two inner electrodes, in cm; R = resistance (= V / I) in ohms 2 A cross section in cm.

5

Polyacetylene conducts very well (a = 1.5 x 10 S / cm), but is not commercially useful due to the high instability of the polymer. Polypyrrole and polythiophene conduct less (0.1-100 S / cm) but are very stable, while the conductivity is sufficient for many applications.

Molding compositions obtained with the method according to the invention can be used in batteries, electronic components (diodes, transistors), electrical wiring, coatings and in EMI shielding attributes. The method of the invention is illustrated by the following examples without being limited to them.

Example I

A) 2.8 g of polyvinyl acetate (Mv 1,100,000 g / mol) is dissolved at room temperature in 28 ml of liquid pyrrole (Merck), which has been purified again with vacuum distillation before use.

Stirring is continued during dissolution.

The resulting concentration of the polyvinyl acetate was 9.4% by weight.

B) A second solution was obtained by dissolving 90 grams of FeCl3.6 H2O in 100 ml of water at room temperature.

Solution A was spread on a Mylar film (polyethylene terephthalate film) using a smoothing knife (opening 0.5 mm).

A liquid film of 0.5 * 50 * 50 mm was obtained.

The liquid film was immediately immersed in 38 ml of solution B. The temperature was 21 ° C.

The originally transparent liquid film quickly turned black, indicating the formation of polypyrrole.

After 60 minutes, the resulting coherent black film was washed with ethanol and then with water and dried.

The conductivity of the film, determined by the four-point measurement, was 1.5 S / cm.

Example II-IV

The procedure of Example I was repeated, however, with varying residence time of the liquid film in solution B. *

The results are summarized in Table 1.

TABLE 1

Example Residence time Conductivity (min.) (S / cm) II 10 1.4 III 5 1.1 IV 1 1.3

Example V

A. Pen test

10 grams of polyvinyl acetate (Mv = 1,100,000 g / mol) was dissolved at room temperature in 100 ml of liquid pyrrole. The resulting concentration of the polyvinyl acetate was 9.4% by weight. Then a rod (chrome / nickel, diameter 0.2 mm) was inserted 5 mm into the solution. The temperature was 21 ° C. A thread was then drawn out of the solution with the rod at a constant speed of 500 mm / min. The wire broke at a length (the distance between the end of the rod and the solution) of 90 mm.

B. Spin test

Fibers were spun from the solution mentioned in Example VA. For this, the solution was placed in a cylinder. The solution was forced through a capillary (0.5 mm diameter) at a temperature of 21 ° C with a piston coupled to a variable speed motor. It turned out to be possible to wind spun thread on a galet with winding speeds between 3.6 and 54 m / min. The distance between spin capillary and galette was 15 cm. *

Example VI

The procedure of Example VA was repeated, but with variation of polymer type, molecular weight and polymer concentration.

The results are summarized in Table 2.

TABLE 2 type molecular weight polymer filament polymer M, fracture concentration, after _ (kg / mol) _ (wt%) _ (mm) _ polyvinyl- 110 51 43 acetate, 38 8 branched (PVAc) polyvinyl- 1,100 13.5 85 + acetate, 9.4 90 branched 5.0 18 (PVAc) polyethylene- 100 5.0 10 oxide (PEO) 2.5 5 polyethylene- 4,000 1.0 25 oxide (PEO) 0.5 15 0.2 8

The table shows that a minimal amount of matrix polymer can be added if it is substantially unbranched.

My = viscosity average molecular weight.

M * weight average molecular weight.

W.

Claims (10)

A process for the preparation of an intrinsically conductive molding compound obtained by in situ polymerization of monomers which form an intrinsically conductive polymer after polymerization, in the presence of a matrix polymer and a catalyst, characterized in that the matrix polymer is dissolved in a , essentially pure momomer mixture, after which the resulting mixture is brought into the desired shape and the monomers are polymerized in situ in the presence of a catalyst. A process according to claim 1, characterized in that (a) a matrix polymer is dissolved in the monomer mixture, the amount of matrix polymer being at most 95% by weight, based on the monomer mixture; (b) after which the resulting mixture is brought into the desired shape; (c) wherein the monomers are polymerized in the presence of a catalyst consisting of a salt of a halogen and a transition metal; (d) optionally followed by a doping step, after which an intrinsically conductive molding compound is obtained. Method according to any one of claims 1-2, characterized in that a thread of at least 5 mm can be drawn from the mixture of monomers, matrix polymer and catalyst at a drawing speed of 500 mm / min. Process according to any one of claims 1-3, characterized in that the monomer mixture consists of pyrrole, thiophene, benzene, aniline, furan and / or derivatives of said monomers. Process according to any one of claims 1 to 4, characterized in that the matrix polymer has a molecular weight (Mw) of at least 100,000 g / mol. Process according to any one of claims 1 to 5, characterized in that the matrix polymer is substantially unbranched. Molding compound obtained by the method according to any one of claims 1-6. Fiber obtained by the method according to any one of claims 1-6. Film obtained by the method according to any one of claims 1-6. 10. Method described in whole or in part in the description and the examples. EXTRACT The invention relates to a process for the preparation of an intrinsically conductive molding compound obtained by in situ polymerization of monomers which, after polymerization, form an intrinsically conductive polymer, in the presence of a matrix polymer and a catalyst, wherein the matrix polymer is dissolved in a essentially pure momomer mixture, after which the resulting mixture is shaped and the monomers are polymerized in situ in the presence of the catalyst. Molding compositions obtained with the method according to the invention can be used in batteries, electronic components (diodes, transistors), electrical wiring, coatings and in EMI shielding attributes.