Process for producing metal-coated materials

Translation of description of equivalent WO 9720084 A1

A process for the production of metallized materials

The invention relates to a process for the preparation of metal¬ ized materials and particularly to such a method in which the desired metal is deposited in a non-electrochemical manner on the material.

The application of metal layers on non-conductive materials or conductive materials such as metal, is required in many industries and practiced in different variants technology. The aim of this treatment, it is in particular to obtain antistatic or conductive surfaces or to provide an electromagnetic shield available. Next metallization to achieve a desired optical effect, such as a metallic "look", or to obtain improved or more abrasion-resistant surfaces can be used. Finally, the metallization of Werkstoffoberfla¬ has Chen also in the manufacture of printed circuit boards of great importance.

To carry out the metallization, ie the application of the metal on the material, in addition to known electrochemical non-electrochemical method, also known as chemical

Deposition processes are referred to. such chemical Method proceeds usually a suitable surface treatment of the material requires, and they are known for various metals such as Au, Ag, Pd, Cu, Sn, or Ni. Often be applied after previous chemical metallization additionally electrochemical methods to increase the layer thickness of the deposited metals.

However, the known chemical processes result in various applications in poor properties in the deposited metal layers or metallized materials. Thus, the layers obtained are often only irregularly or they show a lack of elasticity or brittleness. Further, the known methods are inefficient, since they often erforden the use of large quantities of mostly toxic chemicals.

The invention is thus based on the object to provide a nicht¬ electrochemical process for the production of metallized materials is available, which is superior to the known processes with regard to the above-mentioned aspects.

This object is achieved, surprisingly, by the novel process according to claims 1 to 10th

The invention also relates to the use of intrinsically conductive polymers in the non-electrochemical application of metals to materials according to claims 11 and 12. FIG.

The inventive method for producing metallized materials is characterized in that

(A) the material to be metallized bands with a coating which contains intrinsically conductive polymer, - 3 -

(B) the intrinsically conductive polymer is activated by reduction and

(C) the metal is applied to the material in a non-electrochemical manner by bringing the coated material with a solution containing ions of the metal is brought into contact.

Among the employed in the process "intrinsically conductive polymers" are understood to be organic polymers that polyconjugated bond systems, eg double bonds, aromatic or heteroaromatic rings or triple bonds. Examples of such polymers are polydiacetylene, polyacetylene (PAC), polypyrrole (PPy), polyaniline (PAni), polythiophene (PTh), polyisothianaphthene (PITN) polyheteroarylene vinylene (PArV), wherein the heteroarylene group can be eg thiophene or pyrrole, poly -p-phenylene (PPP), polyphenylene sulfide (PPS) Polyperinaphthalin (PPN), polyphthalocyanine (PPhc) and derivatives thereof (for example, are built up from monomers substituted), their copolymers and their physical mixtures. They may be in different states, which are described by formulas respectively different Summen¬ and usually substantially reversibly can be converted by reactions such as oxidation, reduction, acid / base reaction or complex formation with one another. These reactions are sometimes referred to in the literature as "doping" or "compensation". At least one of the possible states is electrically very conductive, eg has a conductivity of more than 1 S / cm (as pure substance), so that one can speak of intrinsically conductive polymers. Sometimes the intrinsically conductive polymers in the literature also referred to as "organic metals".

A good overview of already synthesized to date intrinsically conductive polymers suitable according to the invention are, one finds eg in Synthetic Metals, books 17, 18 and 19 (1987).

The force applied in step (a) coating can in particular be a polymer blend containing intrinsically conductive polymer. In addition to intrinsically conductive polymer, the polymer blends erfindungs¬ used according to contain other polymers, copolymers or polymer mixtures, such as polyamides, polyesters, polyethers such as polyethylene oxide, copolymer latexes, water-based, such as Vinylacetatbutylacrylat, or other copolymer latices, and / or polyvinyl alcohols , Particularly preferred further polymers are polyamides.

Advantageous polymer blends have a content of preferably 0.1 to 45 wt .-% and particularly preferably 5 to 35 wt .-% intrinsically conductive polymer.

It is also possible, that are used as coating for pure intrinsically conductive polymers.

To be particularly advantageous, it also has been found, when the intrinsically conductive polymer is used in the form of a dispersion. This can be a dispersion in organic solvents, such as alcohols or N-methylpyrrolidone, or in aqueous solvents. The dispersions can also contain binders, such as polymers or film-forming binder, for example, contain the stated as a component of the polymer blend above other polymers.

As a preferred intrinsically conductive polymer is polyaniline is used.

To apply the coating conventional methods, such as mechanical deposition using a doctor blade or immersion in solutions or dispersions of intrinsically conductive polymer, are used. In process stage (b) activation of the intrinsically conductive polymer is performed by this is reduced. The reduction can take z. B. electrochemically, ie with the aid of an externally applied electric current. However, it is preferred that the reduction through the use is performed by chemical reducing agents. As chemical reducing agents in particular H come of it₂, Hydrides, such as borohydrides, for example, BH₃, And / or with respect to the intrinsically conductive polymer reducing action metals such as iron, aluminum or copper, in question. Whether a metal with respect to the polymer has a reducing effect of course depends on the actually chosen conditions under which the reduction takes place. An important influence can usually exercise as the pH and the presence of complexing agents.

Particularly preferred reducing agents are hydrazine and hydrazine compounds such as hydrazine salts, including hydrazinium, proved.

To improve the stability and reproducibility of the activation, the reduction is preferably carried out in a degassed, that is oxygen-poor or -free medium. However, specific applications of the method are conceivable in which the presence of oxygen is not detrimental, but even desirable.

In the case of the preferably used as intrinsically conductive polymer polyaniline, the reduction is often also be recognized by a color change which is due to the formation of the reduced form of the polyaniline, the so-called leucoemeraldine.

In process step (c), the selected metal is applied in nicht¬ electrochemical manner to the material by bringing the coated material having a metal ion-containing solution is brought into contact. Typically, this process step is carried out after step (b). However, it is also possible that at the same time also been carried out with the reduction, the non-electrochemical deposition of the metal on the coated material. An example of this is the tin-plating of copper according to the invention, as is further explained in more detail below and in the Examples. In some cases, however, the simultaneous implementation of (b) and (c) may for example be not desired another or due to procedural aspects because of the incompatibility of employed in (b) and (c) chemicals.

Application in "a non-electrochemical manner" is meant a process in which the application is not performed by use of an externally applied electric current. Rather, the material provided with the polymer-containing coating is brought into contact with the metal ion solution, for which usually sufficient simply dipping into the solution.

It is preferable that in the solution to such a single- or divalent cations of the metal and in particular an aqueous solution is used with a pH value of <. 7

The inventive method allows easy and efficient metallization of materials with metals, and it has been especially upon the application of Cu, Ag, Pd, Sn, Pt and / or Ni has proved advantageous. Particularly preferred is the process for the application of Cu, Ag, or Sn.

The materials come principally plastics of all types, especially those with content of polyamide or polyethylene terephthalate, glasses or ceramics in question. However, other materials such as metallic materials, are metallized with the inventive method. On the Mechanism of the inventive method it is assumed that the reduced intrinsically conductive polymer coating as electron carriers and thus acts as a catalyst and the reducing agent used does not interact directly with the ions of the metal to be deposited and this reduces not directly. The electron transfer from the intrinsically conductive polymer to the metal cations then results in a deposition of elemental metal on the coated material. The concomitant oxidation of the conductive polymers leads at least partly to a regeneration of the conductive polymer used and opens the possibility to submit this again the reduction and deposition steps (b) and (c). Given this proposed reaction mechanism can thus speak of a catalytic activity of the intrinsically conductive polymers.

Particularly illustrative of the surprising catalytic Funk¬ tion, the coating with intrinsically conductive polymer is the tin deposit inventive copper.

In the conventional non-electrochemical tinning of copper is commonly used for. Example methane sulfonic acid and thiourea Sn 2 + solutions. The task of the thiourea is apparently to allow the by complexation with Cu (+ I) the dissolution of copper as copper methane alone is not up or dissolves. Further, due to the negative potential of the Cu (I) -

Thioharnstoffkomplexes to relatively uncomplexed Cu (I) is a

EElleekkttrroonneennltransfer to Sn ⁺ and therefore its reduction to Sn,

Expressed in mole must be theoretically twice as much dissolved Cu in this tinning of copper, as you want to deposit Sn. actual fact, however thorough

Analysis of the increase of the Cu (II) concentration and the decrease the Sn (II) concentration in the tinning solution during the tinning of relatively large Cu surfaces in operational applications results in a Cu (II): Sn (deposited) ratio of 2 such 1.22. The reason for this is in the literature so far not known.

. As shown in Fig 2, giving way to the rise in the Cu (II) - from and the decrease in the Sn (II) concentration in the conventional nicht¬ electrochemical tinning of the initially correct linear development above certain concentrations. Here is the well-known from the technical literature and indicated the manufacturer phenomenon that the tinning above a Cu concentration of 0.08 mol / 1 or below a Sn (II) concentration of 0.1 mol / 1 no longer runs as desired, and therefore the tinning can no longer be used and must be replaced. To explain it is stated that outside the recommended concentration ranges, rather than pure tin coatings undesired intermetallic phases (Sn-./Cu_y) Deposit. The functioning of the tin on the copper layer is then no longer guaranteed.

Particularly strong is the deviation from linear Verhal¬ th if, instead of the total concentration of Cu (II) - which can be converted for chemical reasons only after some days, when the total Cu (I) amount to Cu by atmospheric oxygen (II) was able to determine - that Cu (II) amount detected, which occurs immediately during the coating sequence. By doing that measured the dynamics of the Cu (I) / Cu (II) -Reaktio- NEN, the difference between the total amount of dissolved copper ions and those which we will call the "dynamic", Cu (I). This curve is referred to in Figure 2 as "Cu (I) after tinning", and it is particularly non-linear, as soon as the critical Cu concentration is achieved. If, now, instead of uncoated copper surfaces such, in the present invention provided with a thin coating of conductive polymer, which is reduced under the tinning by the copper, then shows a very different behavior. Sn (deposited) ratio to the ideal value of 2 and is 1.63: now the Cu (II) approaches. In addition, is shown as Figure 1, the course of the increase in total-Cu (II) -. And also the dynamic Cu (I) - concentration as well as the lowering of the Sn (II) concentration over the entire range of concentrations linear. Also significantly above the critical concentrations to concentrate development is clearly linear, without changing the pitch. This behavior in the tinning of the invention is discussed in more detail in Example 3. FIG.

These results are parallel with those that would result from the analysis of the thickness of tin achieved. It is shown that the layer thickness in the tinning of copper without a coating with intrinsically conductive polymer from about 0.6 m²/ L (area of ​​copper per volume tinning) significantly decreases, while in the case of the present invention carried out tin remains substantially constant.

It follows as a practical advantage of the invention that no intermetallic phases are separated, which could reduce or cancel the intended function of the tin layer, and per liter of tinning bath used is more than twice as large area can be coated, as this chemical with conventional deposition method is possible.

The case of the tin-plating of copper to the inventive method clearly shows the catalytic function of the intrinsically conductive polymer employed. It is believed that in this particular example in the case of metallization polyaniline as polymer of this Cu to leucoemeraldine is reduced, which then in turn Sn²⁺ reduced to Sn °, while the oxygen present to Cu Cu ⁺ oxidized.

In any case, the immersion of a surface coated with the polymer copper plate under saline water already leads to the reduction of the polyaniline, which at sufficiently large layer thicknesses of polyaniline, such as 1-5 microns, can be detected visually from its discoloration on the formation the colorless leucoemeraldine is due as a reduced form.

Finally, the invention also relates to the use of intrinsically conductive polymers in the nicht¬ electrochemical application of metals to materials. In this case, particularly, the procedure, as described above for the inventive process.

Advantageously, the use, by

(A) the material to be metallized bands with a coating which contains intrinsically conductive polymer,

(B) the intrinsically conductive polymer is activated by reduction and

(C) the metal is applied to the material in a non-electrochemical manner by bringing the coated material with a solution containing ions of the metal is brought into contact.

The invention is further illustrated in the following examples. Examples

Example 1 Metallization of Polyamide with Copper

A 4 wt .-% polyaniline polymer blend containing polyamide-based, namely Ormecon 900187/34 of Ormecon, Ahrensburg, was applied to a polyamide film of PA6 Ultramid B3L of BASF with a knife in a layer thickness of 100 microns. The coating was green. The film was dried for 20 minutes at 80 ° C.

For the metallization, the coated film was immersed in 1 N sodium hydroxide solution, which contained 13 g / 1 hydrazinium sulfate, and kept there at room temperature for 24 hours under nitrogen for reduction. When immersed in the reducing medium, the coating immediately turned deep blue. In the course of reducing the color of the polyaniline layer changed into gray. After withdrawing from the reduction solution, the film was rinsed with distilled water under nitrogen and immediately transferred to a solution of 0.1 N copper tosylate / 0.01 N dodecylbenzenesulfonic with a pH. 4 Here, it was left for copper deposition for 5 hours under nitrogen. The color of the surface changed to greenish brown. Subsequent rinsing with distilled water, the surface to remove adherent copper salts for a minute was immersed in aqueous ammonia solution. After renewed rinsing with water which now bronzefarbene film was air dried.

All the above treatments, unless stated otherwise, carried out at room temperature, and the solutions used were freshly prepared before use, degassed and rinsed 5 minutes by nitrogen. By X-ray fluorescence upon excitation with Ge target at 25 KV and 1.0 mA, the deposited on the polyaniline copper was identified at 8.05 and 8.91 keV from peaks.

By repeating several times the chemical redox processes, ie reduction and metal deposition, the amount of deposited copper could be increased.

Example 2; Metallization of polyethylene terephthalate

silver

A 4% wt .-% polyaniline polymer blend containing polyamide-based, namely the paint Ormecon 900187/34 Ormecon, Ahrensburg, was applied with a doctor blade in a layer thickness of 50 microns on a polyethylene terephthalate (PET) film. The green coated with the coating PET film was after a drying period of 10 minutes at 80 ° C with silver.

For this purpose, the coated PET film was immersed in sodium hydroxide solution which contained 30 g / 1 hydrazinium sulfate. The pH of the solution was 9 to 10. The film was stored for 12 hours for reduction in this solution under nitrogen. After the coating of the film when immersed in the solution immediately turned blue, she had a yellow color after reduction. After withdrawing from the reduction solution, the film was rinsed under nitrogen with distilled water and once in a 0.33 molar para-toluene sulfonic acid solution having a pH of 1, 11.2 g / 1 of silver nitrate for 30 minutes for silver deposition immersed. The color of the surface of the film changed to green. After a few minutes, a silver deposition was already visible. After rinsing with distilled water, the film was dried in air.

All the above treatments were, unless otherwise indicated, carried out at room temperature, and the used Solutions were prepared freshly before use, degassed and rinsed 5 minutes by nitrogen.

Using X-ray fluorescence analysis was the deposited on the polyaniline coating silver are uniquely identified from peaks at 2.98, 3.14 and 3.23 keV. In addition, only the sulfur peaks at 2.30 and 2.47 keV were recognizable, which originated from the counterions of the polyaniline.

Example 3: Dry deposition of tin on copper

The surface of copper plates was chemically tinned. The tin was made according to the invention with coating of copper plates with an aqueous polyaniline dispersion, eg Ormecon 900236/04 Ormecon Chemie, Ahrensburg. For comparison, the tin plating was also performed without polyaniline coating.

execution

The surface of the copper plate, which should be tinned was determined by measurement. For degreasing the surface and to remove the oxide layer or the copper from tarnishing protective zinc chromate or a micro-etching of the plate was carried out. The copper plate was added at room temperature for two minutes in the commercial acid pickling Circuposit Etch 3330 based on sulfuric acid and peroxide Shipley, Germany, dipped. The plate was then rinsed with water and applying a polyaniline coating for one minute in an aqueous polyaniline dispersion, namely the diluted with water in the ratio 1:19 Ormecon dipped 900 236/04-Konzent.rat (Ormecon, Ahrensburg). After rinsing with water, the plate LT-34 Immersion ink was in the tinning Tinposlt solution (Shipley, Germany) at 50 ° C non-electrochemically tinned by being immersed in this solution. The 2+

Tinning solution Sn ions, phenolsulfonic acid and thiourea. The deposition reaction started immediately upon immersion of the plate. The plate was pulled after 20 minutes from the tinning, rinsed with water and dried. The surface was now coated with a satin silver-colored tin layer.

For comparison, the above steps were repeated with the difference that a polyaniline coating was not applied.

Analytik

A. Determination of Tin in Tinposit LT-34 Immersion Tin Solution

Tin, which was present in 2-valent form, was in buffered with sodium acetate solution III quantitatively determined directly with xylenol orange as an indicator by titration with titriplex.

Determination procedure

2 ml of Tinposit LT-34 Immersion Tin solution were diluted with water to 100 ml with 1 ml conc. HCl and adjusted with sodium acetate to a pH value of about the fourth After addition of xylenol orange indicator trituration was titrated to the last permanent color change to bright yellow with 0.1N titriplex III solution from violet.

calculation

1 ml of 0.1 mol / 1 titriplex III solution = 11.869 mg Sn

B. Copper determination in Tinposit LT-34 Immersion Tin Solution

Copper, which was present in 2-valent form, was prepared by adding ammonia spectrophotometrically determined as copper tetraamine. Determination procedure

0.5 ml of t Tinposi LT 34 Immersion Tin solution were concentrated to 5 ml. Ammonia (25%, pure) are added, shaken well, and the white precipitate of Sn (OH)₂ (Actually stannous oxide hydrate complicated composition) was about 5 minutes with a filter funnel (porosity 3) filtered. The clear filtrate was measured in a 10 mm glass cell in the UV / Vis spectrophotometer in the range from 1000 to 400 nm. As a reference a pure spectrum ammonia solution (25%) was used. From the extinction of the maximum at about 630 nm, the copper ion concentration was determined using a calibration curve.

calculation

Calibration curve: y = 0.0913 x + 0.035 = measured with absorbance y and x = Cu ⁺ in g / 1

C. Determination of Tin on the copper surface

To determine the thickness of the deposited nen on the copper tin tin was dissolved with acid and determined quantitatively in the resultant solution by titration with titriplex III.

Determination procedure The tinned copper plate was immersed to at 50 ° C for 10 minutes in concentrated hydrochloric acid and then rinsed with water. Rinse water and the amount of acid used for dissolution were combined, made up with water to 100 ml and brought to a pH of about 1 with sodium hydroxide pellets. Sodium acetate then a pH of about 4 was adjusted and after the addition of xylenol orange indicator trituration was titrated with 0.1 N titriplex III solution from violet to the last permanent color change to bright yellow. Measurement results

By analytical studies of tin and copper content of Tinposit were determined LT-34 Immersion Tin solution in g / 1 for the respective m tinned copper plate surface per liter of solution. The decrease in the tin content and the increase in the copper (II) concentration were converted for better comparison in mol /. 1 The determination of the copper (II) concentration was carried out immediately after removal of the tin plates and 48 hours after the tinning had stood at room temperature in air. The tin content did not change over this period, while the copper (II) content, a strong increase was recorded. This presumably resulted from existing in the tinning solution of copper (I) ions by atmospheric oxygen slowly to copper (II) ions were oxidized. In the spectrophotometric detection of copper ions concentration were detected only Cu (II). The difference in the copper (II) concentration after immediate removal and after 48 hours to let the proportion of copper (I) determine ions in the solution directly after tinning.

In Figures 1 and 2 in tin and copper increase in Tinposit plotted LT-34 Immersion Tin solution to the m to tinned copper surface per 1 solution used. 1 shows the behavior of the inventively metallized copper plate and Figure 2 shows the comparison of the conventionally metallized copper plate, which was not provided with a polyaniline coating.

The comparison of Figures 1 and 2 shows that when the chemical tin plating with a pretreatment in an aqueous dispersion of polyaniline over the entire region a linear increase in the copper concentration and a decrease in the concentration of tin is recorded. The tin deposition takes place upon application of a polyaniline even after exceeding the eingezeich¬ Neten limit for the manufacturer of the tinning guaranteed Scope (Sn content of the solution> 18 g / 1), nor with the same layer thickness. When tinning without polyaniline coating on the other hand occurs from about 0.45 m²/ L tinned area per 1 solution on a negative deviation, and the amount of deposited tin decreases when the given limit is exceeded.