MXPA01002548A - Printed conductors made of polyalkylene dioxythiophene - Google Patents

Abstract

The invention relates to a method for coating substrates such as paper or plastic films with open, electrically conductive structures using an inkjet printing method. A polymer solution made of water-dispersible polyalkylene dioxythiophene is used for printing.

Description

Printed circuits of polyalcrylene diioxythiophene Description of the invention The invention relates to a process for coating substrates, such as paper or plastic sheets, with open electrically conductive structures by means of inkjet printers or with the help of X-plotters. ,Y. For printing, a polymer solution of water dispersible polyalkylenedioxythiophenes is used.

Known general substrates with electrically conductive structure are the plates for electrical circuits. The plates are composed of a rigid or flexible plastic substrate, on which printed copper circuits are applied. The application of printed copper circuits is done by photo printing or by screen printing.

In the photoprinting according to the positive procedure, copper is first applied over the entire surface of the substrate. A photoresist is distributed over the whole surface of the copper. The photoresist is exposed to light through a template at the sites through which the printed circuits will run. The photoresist material hardens by exposure to light.

Ref: 127441 In the following development, the unhardened fotorresistent.es zones are separated. The copper then discovered is removed with acid in the next step. Only after the separation of hardened photoresist material (strips), are the desired copper printed circuits provided.

In the screen printing process, a layer of the desired conductive structure is printed on a substrate coated on the whole surface with copper, as protection against attack. In the next attack the copper is removed between the desired printed circuits with acid, and then the protection is separated from the attack.

In the direct coating of non-conductive supports with a metallic layer, there may be problems in the adhesion of the metal to the support. In this case, a silk screen printing paste based on an electrically conductive polymer can produce a good bond between the support and the coating. The structures of the printed polymer circuits are printed, for example, by screen printing on a non-conductive substrate and then chemically shrunk (DE 3625587, DE 3627256).

The use of electrically conductive polymers as an electrically conductive structure on substrates is also known in connection with polymer-based electroluminescence publications (Science, October 17, 1997, page 383). For the application of the electrically conductive polymers, a solution of the polymers was introduced into an inkjet printer cartridge and printed on the substrate with the printer. A major problem with this process is that the organic solvent of these polymers, generally a halogenated hydrocarbon or tetrahydrofuran, attacks the plastic of the printer cartridge by dissolving or swelling.

To avoid this drawback, a water-soluble polymer of the type of polythiophene compounds was used by Y. Yang and J. Bharatan (Science, volume 270, February 20, 1998). Through this water soluble polymer, printer cartridges are not attacked. Since the structures of the water-soluble polymers also change with atmospheric moisture, they are suitable only when they do not come into contact with the water again after the separation of the aqueous part in a tempering step. In the publications on polymer-based luminescence, this condition presents no problem, since the conductive structures are encapsulated completely air-tight after separation of the water and after any other eventual processing under inert conditions. However, for open printed circuit structures, ie they are exposed to the surrounding air, water-soluble polythiophenes are not suitable.

The object of the invention was to find a method of preparing open electrically conductive structures on substrates which is carried out more easily and more quickly than the known method of structuring with printed copper circuits, and which gives rise to structures of stable printed circuits under normal conditions.

The objective according to the invention is achieved by printing the conductive structures on a substrate with an inkjet printer or X, Y plotter, in whose cartridge there is an aqueous dispersion of polyalkylenedioxythiophenes with a suitable polyanion as counter-ion.

As a substrate, paper or plastic sheets can be used.

The polyalkylenedioxythiophenes are cationically charged and consist of structural units of formula (I) in which A1 and A2 independently represent one of another alkyl (C, -C4), or together they form alkylene (C, -C4) substituted where appropriate, and n represents an integer from 2 to 10,000, preferably from 5 to 5,000 in the presence of polyanions.

The preferred cationic polyalkylenedioxythiophenes are constituted by structural units of formula (Ia) or (Ib) in which R, and R2 represent, independently of one another, hydrogen; alkyl (C, -C, 8) substituted, if appropriate, preferably (C, -C, 0), especially alkyl (C, -C6); alkenyl (C2-C2), preferably (C2-C8) alkenyl; cycloalkyl (C3-C7), preferably cyclopentyl, cyclohexyl; aralkyl (C7-C, 5), preferably phenylalkyl (C, -C4); aryl (C6-C, 0), preferably phenyl, naphthyl; Alkyloxy (C, -C, 8). preferably (C, -C, 0) alkyloxy, for example methoxy, ethoxy, n- or isopropoxy; or alkyloxy ester (C2-CJ; R3 and R4 represent, independently of one another, hydrogen, but not both at the same time, with at least one alkyl (C, -CI8) substituted with a sulfonate group, preferably (C~-Cl0), especially alkyl (C, - Cel); (C2-C12) alkenyl, preferably (C_-C8) alkenyl, - (C3-C7) cycloalkyl, preferably cyclopentyl, cyclohexyl; aralkyl (C7-C, 5), preferably phenylalkyl (C, -C4); aryl (C6-C, 0), preferably phenyl, naphthyl; (C, -C, 8) alkyloxy, preferably (C, -C, 0) alkyloxy, for example methoxy, ethoxy, n- or isopropoxy; or alkyloxy ester (C2-C, 8). n represents a number from 2 to 10,000, preferably from 5 to 5,000.

Especially preferred are the cationic or neutral polyalkylenedioxythiophenes of formulas (Ia-1) and / or (Ib-1). in which R3 has the meaning indicated above, and n represents an integer from 2 to 10,000, preferably from 5 to 5,000.

The anions of polymeric carboxylic acids, such as polyacrylic acids, polymethacrylic acids or polymaleic acids, and polymeric sulfonic acids, such as polystyrenesulfonic acids and polyvinylsulfonic acids, serve as polyanions. These polycarboxylic and polysulphonic acids can also be copolymers of vinylcarboxylic acids and vinylsulfonic acids with other polymerizable monomers, such as esters of acrylic acid and styrene.

The polystyrenesilphonic acid anion (PSS) is especially preferred as the counterion.

The molecular weight of the polyacids provided by the polyanions is preferably between 1,000 and 2,000,000, with 2,000 to 500,000 being especially preferred. The polyacids or their alkali metal salts can be obtained commercially, for example polystyrenesulfonic and polyacrylic acids, or are preparable by known processes (see Houben Weyl, Methoden der organischen Chemie, Vol. E 20 Makromolekulare Stoffe, part 2, (1987), p. 1141 et seq.).

Instead of the free polyacids required for the formation of the polyalkylenedioxythiophene and polyanion dispersions, mixtures of alkali salts of the polyacids and the corresponding amounts of the monoacids can also be used.

In the case of the formula (Ib-1), the polyalkylenedioxythiophenes carry positive and negative charge in the structural unit.

The preparation of polyalkylenedioxythiophenes is described, for example, in EP-A 0440957 (= US-A-5300575). The polyalkylenedioxythiophenes are prepared by oxidative polymerization. Therefore they contain positive charges, which are not represented in the formulas because their number and position are not perfectly verifiable.

The advantage of the method according to the invention is that electrically conductive open structures of comparable quality can be prepared to copper printed circuits known as flat bars, but with fewer process steps and more easily realizable. For preparation, an inkjet printer with the corresponding prepared printer cartridge and a computer for controlling the printer are sufficient. The desired printed circuit structure can be projected onto the computer screen and printed immediately on an appropriate substrate.

The polyalkylenedioxythiophene dispersible in water is not soluble in water and forms a long-term stable conductive structure also under normal conditions.

Figures and examples The images show: Fig. 1 The Bayer cross printed on paper with poly- (3,4-ethylenedioxythiophene) (PEDT) and polystyrene sulfonate (PSS) Fig. 2 Schematic of printed circuits on paper with PEDT / PSS Fig. 3 Circuit diagram of printed circuits on sheets of polyethylene terephthalate (PET) with PEDT / PSS.

Example 1 Preparation of a dispersion of 3,4-polyethylenedioxythiophene g of free polystyrenesulfonic acid (molecular weight Mn of about 40,000), 21.4 g of potassium peroxodisulfate and 50 mg of iron (III) sulphate in 2,000 ml of water with stirring were placed. 8.0 g of 3,4-ethylenedioxythiophene were added with stirring. The dispersion was stirred for 24 hours at room temperature. Next, 100 g of anion exchanger (commercial product Lewatit MP 62 of Bayer AG) and 100 g of cation exchanger (commercial product Lewatit S 100 of Bayer AG), both moistened with water, were added and stirred for 8 hours.

The ion exchangers were separated by filtration through a polyacrylonitrile fabric with a pore size of 50 μm. A dispersion prepared for use of 3, 4-polyethylenedioxythiophene (PEDT) with polystyrene sulfonate (PSS) as counter-ion (see II) is obtained with a solids content of about 1.2% by weight.

The dispersion can be easily filtered through a 0.45 μm filter, and used after filtration for the preparation of inks for inkjet printers.

(II) E n gle 2 A vacuum inkjet printer cartridge for an HP-DeskJet PLUS inkjet printer was filled with the aqueous dispersion of PEDT / PSS according to (II) of Example I.

(Hewlett-Packard company). The cartridges, well cleaned after opening, were hermetically sealed again with a polyethylene adhesive from the company Henkel after filling with the PEDT / PSS dispersion according to (II). An inkjet printer cartridge thus prepared was used in the HP DeskJet PLUS inkjet printer, which served as a reservoir of printing liquid for the application of the PEDT / PSS dispersion by the control of the printer by a computer. . With the help of a conventional software program, a print sample was projected onto the computer. An image of the Bayer crosses was selected one below the other (Fig. 1). This image was controlled by computer and printed on paper. The three Bayer crosses can be printed on paper one below the other of PEDT / PSS driver, which shows a blue coloration.

Example 3 The procedure was analogous to Example 2, except that the Bayer crossings were printed on a sheet of 0.1 mm thick polyethylene terephthalate (PET) instead of paper.

Example 4 The procedure was analogous to Example 2, except that a cut of a stage was projected as a sample (FIG. 2) with the software program EAGLE.

This printed circuit sample was printed, as in Example 3, on paper with PDET / PSS.

EXAMPLE 5 The printed circuit diagram of FIG. 3 was printed on a 0.1 mm thick PET film analogously to Example 4. With the aid of a current meter, the electrical conductivity of the printed circuit was checked.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (4)

1. R CVTIMDICATIONS Having described the invention as above, the content of the following claims is claimed as property: 1. A process for the preparation of open structures conducive to electricity on substrates, characterized in that the conductive structures are printed on the substrate with a printer of ink jet or plotter X, Y, in which cartridge is an aqueous dispersion of polyalkylenedioxythiophenes with a suitable polyanion as counter-anion.
2. 2. A process according to claim 1, characterized in that the polyalkylenedioxythiophenes are cationically charged and consist of structural units of formula (I), in which A1 and A2 represent, independently of one another, alkyl (C, -C4), or together form alkylene (C, -C4) substituted where appropriate, and n represents an integer from 2 to 10,000, preferably from 5 to 5,000 in the presence of polyanions
3. A process according to claims 1 or 2, characterized in that the cationic polyalkylenedioxythiophenes are constituted by structural units of formula (la) or (Ib), in which R, and R, represent, independently of one another, hydrogen; (C, -C, 8) alkyl substituted if appropriate, preferably (C, -C, _), especially (C, -C) alkyl, (C2-C12) alkenyl, preferably (C2-C8) alkenyl, cycloalkyl (C3) -C7), preferably cyclopentyl, cyclohexyl, aralkyl (C7-C, 5), preferably phenylalkyl (C, -C4), aryl (C6-C, 0), preferably phenyl, naphthyl; (C, -C ") alkyloxy, preferably (C, -C 10) alkyloxy, for example methoxy, ethoxy, n- or isopropoxy; or alkyloxy ester (C2-C "); Y R3 and R4 represent, independently of one another, hydrogen, but not both at the same time, with at least one alkyl (C, -C18) substituted with a sulfonate group, preferably (C, -C10), especially alkyl (C, - C (C2-C2) alkenyl, preferably (C2-C8) alkenyl; (C3-C7) cycloalkyl, preferably cyclopentyl, cyclohexyl; (C7-C15) aralkyl, preferably phenylalkyl (C, -C4); aryl (C6) -C10), preferably phenyl, naphthyl, (C, -C18) alkyloxy, preferably (C, -C, 0) alkyloxy, for example methoxy, ethoxy, n- or isopropoxy, or (C2-C18) alkyloxy ester. n represents a number from 2 to 10,000, preferably from 5 to 5,000.
4. 4. A process according to claims 1 or 2, characterized in that the cationic polyalkylenedioxythiophenes are constituted by structural units of formula (Ia-1) and / or (Ib-1) in which R3 has the meaning indicated above, and n represents an integer from 2 to 10,000, preferably from 5 to 5,000, and polyanions serve as the anions of polymeric carboxylic acids and / or polymeric sulfonic acids. Printed circuits of polyalogylenedioxythiophene SUMMARY OF THE INVENTION The invention relates to a method for coating substrates, such as paper or plastic sheets, with open electrically conductive structures by inkjet printing. For printing, a polymer solution of water dispersible polyalkylenedioxythiophenes is used.