WO2007054229A1

WO2007054229A1 - Carrier with porous vacuum coating

Info

Publication number: WO2007054229A1
Application number: PCT/EP2006/010469
Authority: WO
Inventors: Hilmar Weinert
Original assignee: Hilmar Weinert
Priority date: 2005-11-08
Filing date: 2006-10-31
Publication date: 2007-05-18
Also published as: WO2007054229B1; EP1945830A1

Abstract

The invention provides a product and methods of its manufacture, which result in coated plastic or metal films or inorganic fabrics, comprising a vacuum deposited inorganic outer layer of from 40 to 1000 nm thickness with a porosity of from 10 to 70% increasing towards the coating surface, wherein the open pore surface is up to 1000 times the geometric surface of the film. The pores are formed in a subsequent step either by eluting a soluble component, or by evaporating a volatile component at an elevated temperature, from a deposited mixed layer. A further non-porous vacuum deposited layer between the carrier and the porous layer may be provided to increase the bonding of the porous layer to the film.

Description

Carrier With Porous Vacuum Coating

The invention relates to a carrier, in particular a film or a nonwoven or web, with a porous coating, and to methods for its manufacturing .

A porous composite in the form of platelets is known from application WO 2004/065295 Al, and is manufactured by vacuum depositing a soluble separating agent onto a carrier, followed by simultaneous evaporating and mixing in the vapor phase of an oxide and a soluble substance, which are together deposited on the carrier. The entire layer system is then immersed, with its support, in a solvent bath, e.g. in water. There the coating comes off the carrier, and the soluble substance dissolves from the mixed layer and leaves behind pores in the oxide layer, which layer disintegrates into small platelets.

Such platelets can be further manufactured into pigments in a variety of ways, by filling organic liquids into their pores.

Also, the manufacturing of mixed layers via vacuum deposition is known from the inventor's application DE 100 00 592 Al according to which metals are incorporated into transparent oxides in order to achieve intensely colored interference layers.

To affix such platelets uniformly onto surfaces would only be possible using an adhesive. This method is used in the application WO 2005/087485 Al for coating fabrics with antibacterial substances such as silver. A disadvantage thereof is the necessity of further process steps and the fact that not all platelets orient themselves coplanarly, some platelets overlap each other and therefore some platelets may come off the support again. The platelets yielded by the method of WO 2004/065295 can, therefore, only be used as a suspension or as a dispersion.

The German patent publication DE 35 87 438 T2 discloses the manufacturing of porous outer layers on non-porous fibers by etching the material with hydrofluoric acid. In this manner, the surfaces of ceramic bodies, fibers and fabrics can be modified. It is, however, a severe disadvantage that the etching process necessitates the use of toxic hydrofluoric acid, and that the specific surface achievable in this manner is rather limited. Also, the necessary subsequent firing step at at least 900⁰C excludes use of plastic films and of metallic films. The etching step takes about 15 minutes and thus limits the material through-put by requiring an accordingly long-length acid bath.

Porous, tightly bonded vacuum deposited layers on films, in particular on such films made of plastic, such as polyethylen- terephthalate (PETP) or polycarbonate (PC) , or on metallic films, would result in highly desirable properties such as a capability to adsorb large quantities of gases, a capability to accommodate liquid substances in pore volumes, or in very hydrophilic surfaces.

It is therefore an object of the invention to provide a ribbon- like, in particular a windable material having on one or both sides thereof porous inorganic layers which are bonded tightly to the substrate and require no adhesive for their deposition; and to provide methods for the manufacturing of the material .

The term "windable" is to be understood to mean the ability of being coiled at least one turn, preferably more than one and in particular plural turns. The term also includes the ability of the material to be unwound without damage after having been wound; insofar, it may additionally mean "unwindable" and

"rewindable" . It does not, however, imply that the material is actually wound.

The object is solved by the product according to claim 33, and the methods of its production according to claims 1 and 15.

The product advantageously has a porosity gradient of from 0,1 to 10 μπf¹, preferably of from 0,5 to 3 μπf¹. Herein, porosity increases towards the surface, i.e. the porosity gradient is positive towards the surface of the coating. This gradient is advantageous in that it allows for a tight bonding to the carrier, yet provides a large specific surface near the top.

The substrate or carrier may be selected from among plastic film, metallic film, and metallic, oxidic, siliceous and ceramic nonwovens or webs and inorganic nonwovens or webs on the basis of carbon, such as carbonic fiber.

Preferably, the inventive porous layers may be of small thicknesses of less than 0,5 μm, yet have specific surfaces of up to 1000 m²/g and more. This is tantamount to an enlargement of the geometrical surface by at least a factor of 1000.

Surprisingly, it was found that tightly bonded composite layers can thus be formed, continuously or discontinuously, even on plastic films, the outer layer at the same time having the desired porosity.

The technical solution to the problem as stated above, according to one embodiment, may comprise vacuum depositing on the ribbon- like carrier a substance selected from a first group of substances having a lesser solubility in a given solvent, or a lower vapor pressure at a given temperature, before vacuum depositing on the ribbon-like carrier a first substance selected from the first group of substances and a second substance selected from a second group of substances having a higher solubility in the given solvent, or else a higher vapor pressure at the given temperature, such that the vapor beams at least partially overlap and a mixed condensate layer is formed. Thereby, between the carrier and the mixed condensate layer, an essentially non-porous intermediate layer is formed. Herein, the (third) substance initially deposited may or may not be identical to the first substances. Such an intermediate layer is advantageous in most cases with respect to durability of the coated material, i.e. is an adherence promoting layer. The thickness thereof is preferably 20 to 500 nm. Provision of the adherence promoting layer is particularly preferred where the first substance is nickel or a nickel alloy because the adhesion of nickel to many a carrier material is inherently poor. In particular, where the first and second substances have different solubilities in a given solvent, a mass-based ratio of the solubility of the second substance to that of the first substance at the given temperature, i.e. a temperature between ambient temperature and the boiling temperature of the solvent, is at least 1000 g/g. Thereby it is ascertained that the more soluble substance is sufficiently completely eluted without the matrix composed of the lesser soluble substance being appreciably dissolved. After the eluting step, the coated carrier is dried to remove residual solvent. Where an organic solvent is employed, a subsequent oxidizing treatment may assist in removing residual solvent .

In particular, the lesser soluble substance may be essentially insoluble in the solvent, meaning the removal rate of the substance layer in contact with the solvent is less than 100 nm of its thickness per day.

In particular, in a dwell time of the coated material in the solvent of less than 60 seconds, at least 90 % of the second, more soluble substance may be eluted. Even at a preferred transport speed of the carrier of at least 0,5 m/s or 100 m²/min, because of the fast elution, the length of the bath can be kept small.

In an alternative embodiment of the inventive manufacturing process, the second component of the mixed condensate layer is evaporated in a subsequent heating step in vacuo, without melting either one of the components of the condensate layer.

The porosity gradient can be achieved by guiding the carrier material, preferably coated with an intermediate layer, past the vapor sources and through the vapor beams in such a manner that the mixing ratio of the first substance to the second substance is varied, preferably reduced, with increasing layer thickness.

Preferably, the vapor sources are arranged such that at any given web position, the deposition of the less soluble or less volatile component is first begun with, and the deposition of the more soluble or more volatile component is then begun with.

In one embodiment, the invention contemplates to prepare, in one and the same run, on a carrier material a silicon oxide layer, manufactured by vacuum deposition of silicon monoxide (SiO) , upon which a mixed layer made up of silicon oxide and common salt (NaCl) is deposited in the same vacuum chamber, wherein the SiO and NaCl are evaporated from two evaporation sources the vapor beams of which overlap. By arranging the vapor sources suitably, it is possible to achieve a smooth transition between the massive layer and the mixed layer, such that after later eluting the salt a positive gradient of the porosity towards the boundary of the coating to the gas phase results. Using metal film as a carrier it is possible to manufacture an entirely inorganic product which may be used at high temperatures. Also, in place of a film, a nonwoven or web consisting of metallic, inorganic or carbon fibers can serve as the carrier. The non- eluting component and the material of the adherence promoting massive layer need not be identical, but may preferably be.

In another embodiment, less volatile and more volatile metals, e.g. nickel and zinc, or nickel, aluminum and zinc, are vacuum deposited in succession on an adherence promoting intermediate layer of SiO or Cr. The mixed condensate layer is then heated in vacuo to 300⁰C to 350⁰C, such that the more volatile metal (e.g. zinc) re-evaporates and a porous layer of the less volatile metal (e.g. nickel, or a nickel-aluminum alloy, respectively) remains. Thereafter, the porous layer may further be tempered or annealed, e.g. to increase catalytic activity and/or mechanical stability. The less volatile mixture component and the adherence promoter may also be identical, in particular if not nickel.

The re-evaporating may suitably be carried out in a vacuum of 10^~6 to 1 mbar, preferably 10^'4 to 10^"2 mbar, wherein the evaporation temperature is set so that an evaporation rate of the second substance is 0,001 mg/cm²-s to 10 mg/cm²-s, preferably 0,01 mg/cm²-s to 2 mg/cm²-s, in order that practical dwell times and, thus, oven lengths result, while ascertaining good stability of the deposited coating.

Herein, the first substance may be an oxide, such as silicon oxide, some titanium oxide or cerium dioxide, or may be a low- volatility metal, such as vanadium, chromium or nickel, while the second substance may be a metal subliming at the evaporating temperature, in particular may be one selected from zinc, antimony, magnesium, calcium, sodium and potassium. Also, the second substance may be an organic or inorganic compound subliming at the evaporating temperature, in particular may be lead sulfide or lithium fluoride.

The mixed condensate layer may be exposed to the atmosphere before the re-evaporating step, or may be subjected to re-evaporation without previously being exposed to the atmosphere. Optionally, the porous matrix remaining on the carrier after re-evaporation, if metallic, may be oxidized.

Depending on the component to be evaporated, the evaporation temperature is 250⁰C to 550⁰C, preferably 300⁰C to 500⁰C, and suitably is more than 50⁰C below the melting point of the second substance or a lower melting eutectic of employed metals.

The deposition temperature and evaporation temperature are understood as being measured at the substrate .

Hereunder, the invention is explained in more detail in conjunction with the following drawings:

Figure 1 shows a system suitable for manufacturing the product according to the invention;

Figure 2 schematically shows a composite layer on a ribbon-like carrier according to the invention;

Figure 3 shows another system suitable for manufacturing the product according to the invention; Figure 4 shows a flow chart elucidating a method according to one embodiment of the invention, which may be carried out with the system according to Figure 1; and

Figure 5 shows a flow chart elucidating another method according to a second embodiment of the invention, which may be carried out with the system according to Figure 3.

Example I :

In an especially adapted film deposition system 1 according to Figure 1, which can deposit plural different substances in the same run, a polyethylene terephthalate (PETP) film 2 of 0,14 mm thickness was guided past three evaporators 3a, 3b, 3c arranged in subsequence by means of two guiding rolls 14, 15. The vacuum was 10^"4 mbar at this stage. While passing the vapor source 3a, initially an SiO layer of 80 nm thickness was uniformly deposited over the web width of 1000 nm. This layer turned into an SiO_x with 1.3 < x < 1.5 by oxygen uptake from the background gas, and from degassing of the film. This layer had the function of an adherence promoter for the subsequent mixed layer . Further downstream, the film was guided via guiding rolls 8 around a separator wall 9, and then past a double evaporator 3b, 3c, from the first crucible 3b of which more SiO evaporated. An NaCl evaporator 3c was arranged such that both vapor beams overlapped. In the direction of web transport, therefore, the concentration of the NaCl mixed into the condensate increased, while at a position where the film left the range of the NaCl vapor, the SiO fraction was already reduced to practically zero. Still further downstream, the film was guided via a tensioning roll 10 and coiled under vacuum. After cooling down the evaporators, and aerating the system, the film coil 4b was removed and, by means of a transport crane 11, was supplied to the rewinder 5 as a film roll 4a¹. In the rewinder 5, the film 2 was guided through a water bath 6 with the coated face down. The NaCl of the mixed layer dissolved, the Na⁺ and Cl^" ions migrated to the aqueous phase, where the water was continuously replaced. A two-stage post-purge 6a, 6b, to which the film was fed via diverter rolls 12, removed residual NaCl from the now porous coating. The film was passed via transport rolls 13 through a hot air flow from nozzles 7, thereby dried, and subsequently- coiled. The film product 4b¹ thus obtained could then be removed from the rewinder by means of the transport crane 11, and subjected to further manufacturing steps.

Example II:

A porous layer was prepared by the vacuum deposition of vanadium metal for the manufacture of a vanadium oxide catalyst with large inherent surface :

A 1.4310 stainless steel sheet of size 300 x 150 x 0,4 mm was high vacuum coated in a discontinuous process at < 10^"4 mbar. The 300 x 150 mm sheet was mounted on a base plate and could be moved at a selectable speed of up to 5 cm/s. As a first layer, a 100 run vanadium metal layer was deposited using an electron beam evaporator, type AIRCO. After that, the sheet was returned into its starting position and covered against stray deposition. From a resistor evaporator arranged downstream adjacent the electron beam evaporator, consisting of a source heated by direct current flow, 1, 3, 5-benzene-tricarbonic acid (CAS Nr. 554-95-0) was evaporated at a measured temperature of 250⁰C. Simultaneously, from the electron beam evaporator, vanadium was evaporated. The evaporation rates from both sources were determined by previous adjustment using an oscillating crystal measurement, of BOC Edwards FTM7 make, and set to equal molar amounts evaporated per unit time. After the heating up of both vapor sources to the desired evaporation rates, the sheet was passed at a distance of 25 cm from the sources with a speed of 2 cm/s at a vacuum pressure of 5 x 10^"5 mbar. The longitudinal distance between the sources was 150 mm in the direction of sheet transportation to achieve good overlap of both vapor beams . After the sheet had been moved past both evaporators, it was inserted into a pouch located in the transport direction to shield it against further deposition. The thickness of the mixed layer was determined as 650 run. The evaporators were turned off and allowed to cool down, and the system then aerated with air. The sheet was swayed in isopropyl alcohol and repeatedly post-purged in frech solvent. The benzene-tricarbonic acid dissolved entirely from the mixed layer. For generating a vanadium oxide layer, the sheet was heated in an air oven for 20 minutes at 350⁰C. The porous vanadium metal thereby turned into V₂O₅.

Example III:

This example is similar to example II: The sheet was heated in vacuum to 200⁰C, as measured by an attached thermocouple (type K sheath thermo element). Instead of 1, 3 , 5-benzene-tricarbonic acid, sodium tetraborate was deposited at ca. 900⁰C. Same was eluted in a bath of de-ionized water with a conductivity of < 2 μS and the sheet purged until the wash water had a value of 10 μS . Thereafter, oxidation was carried out as described for example II, however at 300⁰C and 30 minutes dwell time.

It may be noted that the steel sheets used as substrates in examples II and III are windable within the meaning of the term as contemplated in this application, but not actually wound.

Example IV:

A polyimide film of 0.036 mm thickness, coated according to example I, was ink-jet printed upon with a line pattern using a dispersion of ca. 3 μm copper particles. Due to the good wettability of the surface, the particles partially intruded into the porous matrix of silicon oxide. Subsequently, the line pattern was galvanically bolstered up to about 2 micrometer thickness. The resulting product is suitable for use in the manufacture of RFID-tags . Conductor paths and antenna can be applied cost-efficiently by printing. The metallised paths do not peel from the base. Silver particles can be applied in this manner, too.

In Figure 2, the evolution of the layer thickness and the corresponding substance specific thickness growth rate is schematically shown, when the carrier material is moved past the vapor sources A, B, C: As shown schematically in Figure 2, the thickness of the massive SiO layer from source A increases during passage of the web across source A, and remains constant after having left the range of source A. The mixed layer begins with a layer initially consisting mainly of the SiO from source B, having but a small fraction of NaCl from source C. The SiO growth from source B diminishes in the transportation direction of the web, while the NaCl growth first increases and then diminishes again. The result is a smooth variation of the NaCl fraction and thus, after elution of the NaCl₁ of the porosity. By controlling the deposition rate via the temperature of the three sources, any desired thickness profile of the intermediate layer and the mixed layer can be created.

Example V:

In a differently adapted film deposition system according to Figure 3, which can deposit several different substances in the same run, too, a steel film 2b of 0,14 mm thickness was guided past three subsequently arranged evaporators 3a¹, 3b¹, 3c¹ by means of two rolls 14b, 15b. The vacuum pressure was 10^"4 mbar. In passing the vapor source 3a¹, initially a 80 nm thick chromium layer was deposited uniformly over the entire web width of 1000 mm. This layer had the function of an adherence promoter for the subsequent mixed layer.

In the further processing, the film was guided around a separating screen 9b via diverter rolls 8b, and then past a twin evaporator 3b¹, 3C, from the first, upstream crucible 3b¹ of which nickel was evaporated. A second, downstream zinc evaporator 3c¹ was arranged such that both vapor beams overlapped. In the direction of carrier transport, the concentration of Zn mixed into the condensate therefore gradually increased, at the expense of the nickel fraction, and at a position where the film exited the range of the Zn vapor beam the Ni fraction was reduced to practically zero.

In the further processing, the film was guided via a tension roll 10b and through a slot 36 in a further separating screen 38 serving as a sluice into the vacuum evaporation chamber 22. Here, the film was guided over further tension rolls 26 through an oven 24 having a heating element 34 and a cryo trap 32, wherein the zinc re-evaporated at the prevailing temperature of 300-350⁰C, while the nickel did not, due to its many times lesser vapor pressure at these temperatures. Subsequently, the film was cooled through rolls 26 and was wound under vacuum onto the film coil 4b¹. The evaporation chamber 22 also had a cryo trap 30 for preventing impurification, as well as lead throughs therefore and for the electrical leads 28 for the heater element 34 of the oven 24. In variants not shown, after evaporating the zinc the film was passed through a further oven held at a higher temperature and was heated either in vacuo, or else in an Ar inert gas atmosphere to 700-800⁰C, to achieve a certain sintering of the porous layer for further improvement of the film's mechanical properties.

In Figure 4, a flow chart is shown explaining the first method according to the invention, as can be carried out with the system of Figure 1 (optional steps in dashed boxes) : In step SIa, the substrate is placed in vacuum. The substrate is, in this example, passed through a zone in which an intermediate layer of a third, little soluble or insoluble substance is deposited as an adherence promoter in step S2a. The solvent in question is the one provided in the bath 6, 6a, 6b of Figure 1. The substrate then enters the zone in which the first, little soluble or insoluble substance is deposited (step S3a) . The first substance may be the same as the third substance. Then, in step S4a the substrate enters the zone where also the second, more or even highly soluble substance is deposited. Both substances are deposited simultaneously, but in gradually varying proportion, in step S5a. The support then exits the deposition zones in step S6a, and enters the elution bath in step S7a, where the pores in the matrix bonded to the support are formed. The eluting step may comprise several steps of washing. Thereafter, in step S8a the coated support enters a drying zone. Optionally, the dry product is further subjected to a sintering step S9a, and/or an oxidizing step (not shown) . In a variant, if an organic solvent is used in step S7a, an oxidative treatment SlOa may be carried out between steps S8a and S9a to remove residual solvent.

In Figure 5, another flow chart is shown explaining the second method according to the invention, as can be carried out with the system of Figure 3 (again, optional steps in dashed boxes) : In step SIb, the substrate is placed in vacuum. The substrate is, in this example, passed through a zone in which an intermediate layer of a third, little volatile or non-volatile substance is deposited as an adherence promoter in step S2b. The substrate then enters the zone in which the first, little volatile or non-volatile substance is deposited (step S3b) . The first substance may again be the same as the third substance. Then, in step S4b the substrate enters the zone where also the second, more or even highly volatile substance is deposited. Both substances are deposited simultaneously, but in gradually varying proportion, in step S5b. The support then exits the deposition zones in step S6b. In a variant, the coated, but not yet porous product is then exposed to the atmosphere in step SlOb. Whether or not the non-porous product has previously been exposed to air, it then enters the re-evaporation oven in step S7b, where the pores in the matrix bonded to the support are formed. Optionally, the porous product may be further subjected to a sintering step S9b and/or an oxidizing step (not shown) .

Theoretical Considerations:

Applying in an attempt at estimating and approximately calculating the porosity in accordance with a hard-sphere-model, as a simplification the SiO- and NaCl-molecular distances of the first example may be taken as being roughly equal. From the densities and the molecular weights of SiO and NaCl, it is then possible to determine the volume acquired by each molecule:

L = 6.02 x 10²³ mol^"1 M(SiO) = 60.0 g/mol p (SiO) = 2.13 g/cm³

-> Molar volume (SiO) = 28.17 cm³ /mol M(NaCl) = 58.44 g/mol p (NaCl) = 2.16 g/cm³

-> Molar volume (NaCl) = 27.06 cm³ /mol The cubic volume V, acquired by one molecule, would then be determined as :

Vsio = 28.17 cm³/ (6.02 x 10²³) = 4.67 x ICT²³ cm³

V_Naci = 27.06 cm³/ (6.02 x 10²³) = 4.49 x 10^~23 cm³

The channels resulting from eluting the NaCl approximately have a cross sectional area A per molecule of A_Naci = V^2/3 = 2.72 x io^"15-³³ cm² = 0.126 nm² , or a one-dimensional measure D of order D = V^1/3 = 1.645 x IO^{"7 66} cm = 0.355 nm, respectively.

With a porosity of 50% and a layer thickness of, say, 200 nm, in accordance with a layer model, 100 hollow layers may be taken to be present. Each hollow layer has two faces, i.e. 200 faces in all. The mass of a massive SiO-layer of 200 nm thickness is 0.46 g/m². This results in a porous mass of 0.5 x 0.46/200 g/m² = 0.00115 g/m², corresponding to 869 m²/g. This value is well comparable to that determined by a BET-measurement according to DIN 66131/DIN 66132 within an uncertainty range of +/- 15% from several measurements. The BET-value is independent of the deposited layer thickness and only dependent of the molar ratio of the layer- forming components. By way of measuring the individual evaporation rates of the respective components using known methods, e.g. an oscillating crystal measurement, an accurate adjustment of the porosity is possible before actually mixing the components. There are practical limits to the selected porosity: Layers, the porosity value of which exceeds 70%, tend to have an insufficient mechanical stability and are liable to decompose into loose particles when subjected to even small external forces. The pore volume per unit surface area of the coated film is essentially directly proportional to the layer thickness of the mixed layer. However, small deviations from this proportionality result from the porosity gradually increasing with the growing layer.

The high vacuum deposition process termed PVD-process ("Physical Vapor Deposition"), allows to employ, as an initial layer serving improvement of the adherence between the base material and the subsequent porous layer, the choice of various substances, such as silicon monoxide, aluminum oxide, magnesium fluoride, titanium dioxide or its suboxide, oxides of the lanthanides such as cerium oxide, chromium oxide, or vanadium or chromium metal . The mixed layer deposited thereupon requires a soluble and/or integrally vaporizable in vacuo component from the second group, which component may be inorganic and water soluble, such as NaCl, KCl, water free sodium tetraborate or NaF. Organic substances may also be suitable for this purpose; examples therefor are those mentioned in European patent EP 1 404 763 Bl of the applicant, which organic substances require organic solvents, or pentaerythrite (CAS Nr. 115-77-5) , 1, 3, 5-benzene-tricarbonic acid (CAS Nr. 554-95-0) or other substances, which are water soluble.

The material of the porous matrix may be selected from a wide variety of substances of the first group. These may be oxides, such as silicon monoxide, silicon dioxide, aluminum oxide, oxides of the lanthanides, in particular cerium dioxide, titanium oxide and its suboxides such as TiO, Ti₂O₃, Ti₃O₅, but also metals such as copper, silver, gold, nickel, iron, aluminum, titanium, niobium, tantalum, molybdenum, vanadium, manganese, cobalt, zirconium, indium, silicon, palladium or platinum. In some cases, electron beam evaporation is required. For catalytic applications, these metals may subsequently be oxidized, or may be doted with another metal or oxide in the same PVD-process. A prerequisite therefor is employment of a carrier matching the catalytic process, e.g. a metallic film. Plates, tubes, filling materials such as Raschig rings, saddles and others may be manufactured from such metallic films.

The films may consist of plastics, such as polyethylene terephthalate (PETP) , polyamide (PA) , polyimide (KAPTON^®) , polycarbonate (PC) , but also of metals such as aluminum, austenitic steels or titanium. The porous layers may be provided on one side only of the carrier, or on both sides.

The applications of such porous coatings are manifold. Examples therefor are: - heterogeneous catalysts, tightly bonded to a surface. Here, the carrier film may consist of a suitable metal . Such carrier films are commercially available from thicknesses of 0,02 mm onwards and are well suitable for roll-to-roll- coating under vacuum;

hydrophilic support films for the analytic electrophoresis, but also for recovering materials from the separation of peptides and other high molecular weight substances. Herein, the support film is coated, in an additional process, with a gel, onto which the substances to be separated are applied. Because the porous films described herein are manufacturable in large scale in lengths of some 10³ meters and in widths of one meter, they can be used for continuous cross-flow-electrophoresis;

as a support for adsorbed substances for sensors, medicaments or as a microbe-deterring surface;

- as a highly absorptive surface in the short wavelength infrared range with little emission in the long wavelength infrared range. The porous structure suppresses energy losses through reflexion;

for anchoring printed-on, electrically conductive metal pigments of silver, copper or carbon, wherein the conductive paths may subsequently be galvanically fortified or bolstered.

Due to the wide selection of vaporizable substances, which may be turned into porous layers, there is provided a potential source for further products and applications. The further processing of the coated films and sheets so manufactured into shaped parts is readily possible according to known techniques.

The specific surface of the porous layers is about 50 to 1500 m²/g, in particular more than 200 m²/g. As a carrier, nonwovens, webs or fabrics of metallic or other inorganic fibers, in particular carbon fibers may be employed, but also oxidic, siliceous and ceramic nonwovens, webs or fabrics.

The product is a windable, ribbon-like material with a one-sided or both-sided vacuum coating, which is applied in the same run in the same vacuum chamber in subsequence and comprises:

a) optionally, a layer having a thickness of 20 to 500 nanometers, serving (if present) as an adherence promoter; und

b) thereupon a further layer, deposited by mixing at least two, in particular at most three vapor beams overlapping one another at least in part, consisting of one or maximally two substances which are little soluble or insoluble in a certain solvent, and a further substance which is more highly soluble in that solvent, which vapor beams generated a mixed condensate layer, in which the molar mixing ratio of the more soluble substance and the less soluble or insoluble substance (s) varies with increasing layer thickness,

c) whereafter the coated material is exposed to the solvent, whereby the soluble substance is eluted from the mixed condensate, and in the remaining matrix, open pores are formed with a specific surface of 50 to 1500 m² per gram material,

d) whereafter the ribbon-like, now porous material stripped of the soluble substance is subjected to drying for removing residual solvent .

Alternatively, one or more less volatile or non-volatile substances and a more readily volatile substance are employed for forming the mixed condensate layer, and the more volatile component is subsequently re-evaporated in vacuum at an evaporation temperature above the deposition temperature. Herein the vapor pressures of the first and second substances at the re-evaporation temperature preferably differ by at least a factor of 4, the re-evaporation temperature is below the melting points, and the vapor pressure of the second, more volatile substance preferably is at least 10^"3 mbar at 700⁰C at the most.

The latter method is particularly advantageous for porous layers which are water-sensitive, but relatively little volatile.

The layer for adherence promotion consists preferably of silicon monoxide, aluminum oxide, magnesium fluoride, titanium dioxide or one of its suboxides, an oxide of one of the lanthanides, chromium oxide or chromium metal .

The insoluble substance consists preferably of silicon monoxide, silicon dioxide, aluminum oxide, an oxide of one of the lanthanoides such as cerium oxide, titanium oxide or one of its suboxides such as TiO, Ti₂O₃, or Ti₃O₅, copper, silver, gold, nickel, iron, aluminum, titanium, niobium, tantalum, molybdenum, vanadium, manganese, cobalt, zirconium, indium, silicon, palladium or platinum. These form a first group of lesser soluble and/or lesser volatile substances.

The soluble or, respectively, volatile substance consists preferably of a vacuum-vaporizable and/or water soluble salt, such as NaCl, KCl, sodium tetraborate, NaF, Pentaerythrite CAS No. 115-77-5 or 1, 3, 5-benzene-tricarbonic acid CAS 554-95-0, or a substance such as anthracene, anthrachinone, camphoric acid anhydride, benzimidazole, benzene-1, 2, 4-tricarbonic acid, biphenyl-2, 2-dicarbonic acid, bis (4-hydroxyphenyl) -sulfone, dihydroxy anthrachinone, hydantoin, 3-hydroxybenzoic acid, 8-hydroxychinolin-5-sulfonic acid monohydrate, 4-hydroxy- coumarin, 7-hydroxycoumarin, 3-hydroxynaphthalene-2-carbonic acid, isophthalic acid, 4, 4-methylen-bis-3-hydroxynaphthalene-2- carbonic acid, naphthalene-1, 8-dicarbonic acid anhydride, phthalimide or its potassium salt, phenolphthalein, phenol- thiazin, tetraphenylmethane, triphenylene, triphenylmethanol, or a mixture of at least two of these. These form a second group of more soluble and/or more volatile substances. The thickness of the mixed condensate layer is preferably between 40 or 50 and 1000 nanometers, wherein the concentration of the insoluble or, respectively, non-volatile substance in the layer has a negative gradient over the thickness of the layer (from the inside towards the outer side) .

The porosity of the porous layer is preferably between 10 % and 70 %, that of the intermediate layer is preferably < 2 %, in particular < 1 %, more preferably < 0.2 %.

The porosity gradient is preferably ca. 0.1 to 10 μm^"1, more preferably is 0.3 to 5 μm^'1 , wherein a somewhat extreme example case would be a layer a mere 0.1 μm in thickness, which at its outer surface has twice as much pore space as solid volume, corresponding to a porosity of 67%. In this case, a mean porosity gradient of 6.7 μm^"1 would be reached. After the depositing, but before eluting the more soluble substance, or re-evaporating the more volatile substance, respectively, the mixed condensate layer has two concentration gradients in opposite directions, as well as a gradient G of the molar concentration ratio of the soluble to the insoluble substance, or the volatile to the non-volatile substance, respectively, which in this example would be G = 20 μm^"1: At the lower boundary of the mixed layer, no soluble or volatile substance is present, while at the outer surface the molar ratio of the soluble to the insoluble substance, or the volatile to the non-volatile substance, respectively, is 2. Referring to the layer thickness of, in this example, 0.1 μm, the stated gradient value results. In other examples, the gradient of the concentration ratio is at least 0,5 μm^"1. The measurement of the porosity in different depths can be accomplished, e.g., by SEM-measurements taken on ground facets.

The carrier material preferably consists of polyethylene terephthalate, polyamide, polycarbonate, polystyrene or another plastic manufacturable into films. Alternatively, the carrier material consists of iron, nickel, titanium, copper or an alloy comprising these metals. Furthermore, the carrier may consist of a material comprising, or consisting of, metallic or inorganic fibers, in particular of an oxidic, siliceous or ceramic nonwoven or web or some such of carbonic fibers.

The windable, ribbon-like product thus obtained may be used as a heterogeneous, flat shaped, porous catalyst, consisting of one, in particular maximally two substance. Herein, employing an organic soluble substance is particularly advantageous, all the more if same is essentially tracelessly removed in an oxidative post treatment of the product .

Alternatively, the product so obtained may be used as a gel carrier for an electrophoresis, in particular for a continuous electrophoretic substance separation.

Further, the product so obtained may be used as an adsorbing surface for applying thereon sensor materials, medicaments or microbe-deterring substances; as an infrared absorbing surface with little reflection losses; or as a chromatography carrier.

Finally, the windable, ribbon-like product so obtained may be used as a substrate film for being printed upon with electrically conductive pigments for the manufacture of conductor paths, which in a following process can be galvanically reinforced.

Claims

1. A method for manufacturing a coated, ribbon-like, windable material, the method comprising:

vacuum depositing at least one substance selected from a first group of substances having a lower vapor pressure on a windable ribbon-like material, and vacuum depositing a second substance selected from a second group of substances having a higher vapor pressure on the windable ribbon-like material, at a deposition temperature of the windable material , wherein vapor beams of the at least one substance and the second substance at least partially overlap so as to form a mixed condensate layer; and

evaporating the second substance from the mixed condensate layer at an evaporation temperature so as to form open pores in a matrix of the at least one first substance; wherein the evaporation temperature is selected so that the vapor pressure of the second substance at the evaporation temperature is at least 4 times as large as the vapor pressure of the first substance, and is at least 10^~3 mbar, wherein the evaporation temperature is below the melting temperature of the second substance.

2. The method according to claim 1, wherein the evaporation temperature is between the deposition temperature and the melting temperatures of the first and second substances, and is below 800⁰C, preferably is at most 700⁰C.

3. The method according to claim 1 or 2 , wherein an evaporation vacuum is 10^"6 to 1 mbar, preferably 10^'4 to 10^"2 mbar.

4. The method according to one of claims 1 to 3 , wherein the evaporation temperature is set so that an evaporation rate of the second substance is 0,001 mg/cm²-s to 10 mg/cm²-s.

5. The method according to claim 4, wherein the evaporation rate is 0,01 to 2 mg/cm²-s.

6. The method according to one of the preceding claims, wherein the first substance is an oxide.

7. The method according to one of the preceding claims, wherein the second substance is a metal subliming at the evaporation temperature, in particular is selected from zinc, antimony, magnesium, calcium, sodium and potassium.

8. The method according to one of claims 1 to 7, wherein the depositing is made by sputtering, arc evaporation or physical vapor deposition (PVD) .

9. The method according to one of claims 1 to 5, wherein the second substance is an organic substance subliming at the evaporation temperature .

10. The method according to one of claims 1 to 6, wherein the second substance is an inorganic substance subliming at the evaporation temperature, in particular is lead sulfide or lithium fluoride.

11. The method according to one of the preceding claims, wherein the mixed layer is exposed to the atmosphere before the evaporating.

12. The method according to one of claims 1 to 10, wherein the mixed layer is not exposed to the atmosphere before the evaporating .

13. The method according to one of the preceding claims, wherein the evaporation temperature is 250⁰C to 550⁰C, preferably is 300⁰C to 500⁰C.

14. The method according to one of the preceding claims, wherein the evaporation temperature is more than 50⁰C below the melting temperature of the second substance.

15. A method for manufacturing a coated, ribbon-like, windable material, the method comprising:

- vacuum depositing at least one substance selected from a first group of substances having a lesser solubility in a solvent on a windable ribbon-like material, and vacuum depositing a second substance selected from a second group of substances having a higher solubility in the solvent on the windable ribbon-like material, wherein vapor beams of the at least one substance and the second substance at least partially overlap so as to form a mixed condensate layer;

- eluting the second substance from the mixed condensate layer with the solvent so as to form open pores in a matrix of the at least one first substance; and

drying the matrix.

16. The method according to claim 15, wherein the at least one first substance is essentially insoluble in the solvent.

17. The method according to claim 15 or 16, wherein a ratio of solubilities of the second substance to the first substance at a temperature of the solvent between ambient temperature and the boiling point of the solvent is at least 1000 g/g.

18. The method according to one of claims 15 to 17, wherein in a dwell time of the coated material in the solvent of less than

60 s, at least 90% of the second substance are eluted.

19. The method according to one of claims 15 to 18, wherein the solvent is water or an organic solvent.

20. The method according to claim 19, wherein the solvent is an organic solvent, further comprising an oxidative post treatment for removing residual solvent.

21. The method according to one of the preceding claims, wherein the second group of substances comprises such substances as are integrally vaporable in vacuum.

22. The method according to one of the preceding claims, wherein the first group of substances comprises silicon monoxide, silicon dioxide, aluminum oxide, lanthanide oxide, titanium oxide, titanium suboxide, copper, silver, gold, nickel, iron, aluminum, titanium, niobium, tantalum, molybdenum, vanadium, manganese, cobalt, zirconium, indium, silicon, palladium and platinum.

23. The method according to one of the preceding claims, wherein the matrix comprises cerium oxide or a rare earth oxide, in particular lanthanum oxide or yttrium oxide, or consists of one or more of these.

24. The method according to one of the preceding claims, wherein the second group of substances comprises NaCl, KCl, sodium tetraborate, NaF, pentaerythrite (CAS No. 115-77-5) , 1, 3 , 5-benzene tricarbonic acid (CAS 554-95-0), anthracene, anthrachinone, camphoric acid anhydride, benzimidazole, benzene- 1, 2 , 4 -tricarbonic acid, biphenylene 2, 2-dicarbonic acid, bis (4 -hydroxyphenyl) -sulfone, dihydroxy anthrachinone, hydantoin, 3 -hydroxy benzoic acid, 8-hydroxy chinoline- 5-sulfonic acid monohydrate, 4 -hydroxy coumarin, 7-hydroxy coumarin, 3 -hydroxy naphthalene-2 -carbonic acid, isophthalic acid, 4,4' -methylen-bis (3 -hydroxynaphthalene-2 -carbonic acid), naphthalene-1, 8-dicarbonic acid anhydride, phthalic - imide, its potassium salt, phenolphthalein, phenothiazine, tetraphenyl methane, triphenylene, triphenyl methanol, and mixtures of at least two of these substances .

25. The method according to one of the preceding claims, further comprising vacuum depositing the windable ribbon-like carrier material with at least one third substance of the first group so as to form an intermediate layer before forming the mixed condensate layer .

26. The method according to claim 25, wherein the intermediate layer comprises silicon monoxide, aluminum oxide, magnesium fluoride, titanium dioxide, titanium suboxide, lanthanide oxide, chromium oxide or chromium metal, or consists of one or more of these.

27. The method according to claim 25 or 26, comprising passing the carrier material coated with the intermediate layer past the vapor beams so that the mixing ratio of the first substance to the second substance is varied with increasing layer thickness.

28. The method according to one of the preceding claims, wherein the thickness of the mixed condensate layer is between 50 and 1000 run, wherein the concentration of the first substance or substances in the mixed condensate layer has a negative gradient in the depositing direction before the eluting or evaporating, respectively, of the second substance.

29. The method according to one of the preceding claims, wherein the ribbon-like material comprises polyethylene terephthalate, polyamide, polycarbonate, polystyrene or another plastic manufacturable into films, or consists of one or more of these.

30. The method according to one of the preceding claims, wherein the ribbon-like material comprises iron, nickel, titanium, copper or an alloy of these, or consists of one or more of these .

31. The method according to one of the preceding claims, further comprising a heat treatment for sintering the porous layer in vacuum or in an inert gas, in particular above the drying temperature or the evaporation temperature, respectively.

32. The method according to one of the preceding claims, wherein at a given position of the carrier material, depositing the first substance is begun with before beginning with the depositing of the second substance.

33. A flat material with a coating, in particular obtainable according to one of the preceding claims, comprising

- a windable, ribbon-like carrier material;

a porous layer with a specific surface of 50 to 1500 m²/g, and

- optionally, an essentially non-porous intermediate layer having a thickness of 20 to 500 run arranged between the carrier material and the porous layer,

wherein in the porous layer, a positive porosity gradient exists from the carrier material or from the intermediate layer, respectively, towards the coating surface.

34. The flat material according to claim 33, wherein the coated material is a windable, ribbon-like material.

35. The flat material according to claim 33 or 34, wherein the porosity gradient is 0.1 to 10 μπf¹.

36. The flat material according to one of claims 33 to 35, wherein the carrier material is selected from plastic film, metallic film and materials consisting of metallic, oxidic, siliceous or ceramic fibers or carbon fibers or combinations thereof .

37. The flat material according to claim 36, wherein the carrier material is a plastic film, onto which a gel layer is coated for continuous electrophoretic substance separation.

38. The flat material according to claim 36, wherein the carrier material is a metallic film, further comprising at least one active catalyst component.

39. The flat material according to claim 36, wherein the carrier material is a material comprising metallic, oxidic, siliceous or ceramic fibers or carbon fibers or consisting of one or more of these, further comprising at least one active catalyst component .

40. The flat material according to claim 38 or 39, further comprising at least one catalyst promoter.

41. The flat material according to one of claims 33 to 40, wherein the specific surface of the porous layer is more than 200 m^z/g, in particular is 740 to 1000 m²/g.

42. Use of the material coated according to the method of one of claims 1 to 32, or the flat material according to one of claims 38 to 40, wherein the ribbon-like material is preferably metallic, as a heterogeneous, planar, porous catalyst comprising one or two substances or consisting of one or two substances .

43. Use of the material coated according to the method of one of claims 1 to 32, or the flat material according to claim 37, for an electrophoresis.

44. Use of the material coated according to the method of one of claims 1 to 32, or the flat material according to one of claims 33 to 36, as an adsorbing surface for the application of sensor materials, medicaments or microbe-deterring substances thereon.

45. Use of the material coated according to the method of one of claims 1 to 32, or the flat material according to one of claims 33 to 36, as a low-reflectivity infrared-absorbing surface.

46. Use of the material coated according to the method of one of claims 1 to 32, or the flat material according to one of claims 33 to 36, as a carrier film for printing thereon one or more electrically conductive pigments so as to provide conductive paths, in particular further comprising galvanically increasing a thickness of the conductive paths in a subsequent step.

47. Use of the material coated according to the method of one of claims 1 to 32, or the flat material according to one of claims 33 to 36, as a chromatography carrier.