CA3120783A1

CA3120783A1 - Coated etfe film, method for producing same, and use of same

Info

Publication number: CA3120783A1
Application number: CA3120783A
Authority: CA
Inventors: Ralph Wilken; Matthias Ott; Klaus-Dieter Vissing
Original assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Current assignee: Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
Priority date: 2018-11-23
Filing date: 2019-11-25
Publication date: 2020-05-28
Also published as: EP3883990A1; AU2019385725A1; WO2020104699A1

Abstract

The invention relates to a coated ETFE film, the static water contact angle on the surface of the coating being = 60° and, measured using XPS, at least 1 at% silicon, 1 at% titanium, 1 at% zinc and/or 1 at% aluminum being present at the surface of the coating, with respect to the total number of atoms measured using XPS, with the stipulation that, if of silicon, titanium, zinc and aluminum only aluminum is comprised at the surface, the following applies: between 1 at% and 18 at%, preferably between 3 at% and 15 at% and particularly preferably between 6 at% and 10 at% fluorine, which is not bonded in the form of tetrafluoroethylene units, is comprised at the surface of the coating, with respect to the total number of atoms measured using XPS.

Description

Coated ETFE film, method for producing same, and use of same Field of use of the invention:
The present invention relates to a coated ETFE (ethylene-tetrafluoroethylene copolymer) film, wherein the static water contact angle at the surface of the coating is 600 and there is at least 1 atom% each of silicon, titanium, zinc and/or aluminum at the surface of the coating, measured by XPS, based on the total number of atoms measured by XPS.
The invention further relates to the use of the ETFE film coated in accordance with the invention for the coating of built structures, especially buildings and very particularly greenhouses, and to a process for producing the ETFE film of the invention.
ETFE (ethylene-tetrafluoroethylene copolymer) films are frequently used in the architecture sector on account of their long life, their good UV resistance and their good transparency, especially in the UV range, and their good mechanical and thermal properties.
These films have low surface energy. Low surface energies are advantageous in outdoor settings in order to ensure that water and soil bead off. In indoor settings, low surface energy is frequently undesirable because this can result in formation of condensation water, typically in droplet form, on the surface of the film. This can lead to unwanted dripping of condensation water. Moreover, it is not impossible for there to be a magnifying glass effect when sunlight is focused by the droplet.
Especially in the case of use of films for greenhouse roofs, the formation of condensation water droplets is damaging because both the hanging droplets and dripping onto the plants result in "burning" of the plant leaves and hence reduce the growth and yield of the plants Date Recue/Date Received 2021-05-21

- 2 -to a crucial degree. Moreover, formation of mold is enabled and promoted.
Therefore, especially in the case of roof inclinations greater than 200, no water droplets resulting from condensation water on the inside of the roof surface should drip down or remain for a prolonged period. This is not possible in a sustained manner according to the prior art in the case of use of ETFE films without impairing the good UV transparency of the films.
State of the art:
In the prior art, this object is achieved in that ETFE films are surface hydrophilized, for example, by a corona treatment (cf., for example, EP 2 530 112 Al) or a plasma treatment, for example with oxygen, nitrogen or argon plasmas. This primarily incorporates oxygen atoms at the surface of the film. The effect of this is that polarity rises and hence water is better able to wet the surface.
A disadvantage is that this effect of hydrophilization is subject to aging.
Without being tied to any theory, the ETFE polymer chains have chain segment mobility unlimited by crosslinks or side chains. Furthermore, the ETFE film tries to minimize surface energy. The effect of this is that the activated hydrophilic chain segments "dive" into the material, and untreated or more lightly treated chain segments occur at the surface. As a result, the surface energy of the treated ETFE film decreases again during aging. This effect of minimization of surface energy is accelerated specifically in the case of elevated temperature, since this increases chain segment mobility.
Furthermore, especially after surface activation, ETFE films are coated by wet-chemical means, for example by coating materials (cf., for example, EP 2 397 029 B1), sol-gel systems or else by coextrusion. But a disadvantage here is that UV stability suffers, UV
transparency is lowered and the mechanical properties of the film are altered (e.g. higher basis weight, lowering of thermal film shrinkage). These effects make these solutions unattractive specifically for architecture applications.
The state of the art is represented, for example, by the F-Clean film from AGC
Chemicals Europe, Ltd..
This is an ETFE film equipped with an antidrip coating for use in greenhouses.
A disadvantage of this coating is that it impairs UV transparency. Moreover, in the case of applications in which the film is subjected to higher temperatures for installation (cf., for Date Recue/Date Received 2021-05-21

- 3 -example, WO 2017/153782 A2, page 7 lines 36 ff.), there is degradation and detachment of the coating.
Against this background of the prior art, it was an object of the present invention to provide a solution that retains as many as possible of the positive properties of the ETFE film, and reduces and preferably prevents formation of water droplets, especially condensation water. At the same time, the mechanical properties of the ETFE films in particular should preferably remain unchanged and/or the effect of droplet reduction should be sustained for as long as possible and/or withstand elevated temperatures. In addition, it is further preferable that the desired effects are maintained even on occurrence of the typical film shrinkage of an ETFE film under thermal stress.
This object is achieved in accordance with the invention by a coated ETFE
film, wherein the static water contact angle at the surface of the coating is 60 and there is at least 1 at% silicon, 1 at% titanium, 1 at% zinc and/or 1 at% aluminum at the surface of the coating, measured by XPS, based on the total number of atoms measured by XPS, with the proviso that if, among silicon, titanium, zinc and aluminum, only aluminum is included at the surface: between 1 at% and 18 at%, preferably between 3 at% and 15 at%
and more preferably between 6 at% and 10 at% of fluorine not bound in the form of tetrafluoroethylene units is included at the surface of the coating, based on the total number of atoms measured by XPS.
It has been found that, surprisingly, the ETFE film coated with a silicon-containing layer (and/or a titanium-containing layer and/or a zinc-containing layer and/or an aluminum-containing layer) and having the appropriate static water contact angle retains the positive properties of the ETFE film over a long period and under the constraints of use, and reduces and at best prevents the tendency to form droplets in the event of formation of condensation water.
For avoidance of doubt, the starting water contact angle is determined as described in example 3 in accordance with DIN 55660 DIN.
For the avoidance of doubt, XPS (X-ray photoelectron spectroscopy, also called electron spectroscopy for chemical analysis, ESCA), as described hereinafter in this text, is especially effected here as described in example 2. It should be noted here that the XPS
values, if not especially specified, are always the values at the recording angle of 0 degrees, i.e. orthogonally to the surface or 0 degrees to the surface normal.
Date Recue/Date Received 2021-05-21

- 4 -Preference is given to a coated ETFE film, wherein, irrespective of whether, among silicon, titanium, zinc and aluminum, only aluminum is included at the surface, between 1 at% and 18 at%, preferably between 3 at% and 15 at% and more preferably between 6 at%
and at% of fluorine not bound in the form of tetrafluoroethylene units is included at the

5 surface of the coating, based on the total number of atoms measured by XPS.
In the context of this application, what is meant by "fluorine not bound to tetrafluoro units"
is that this is fluorine that may but need not originate from tetrafluoroethylene units of ETFE.
It is preferable in accordance with the invention that the fluorine comes predominantly from the tetrafluoroethylene units of the ETFE. This fluorine not bound to tetrafluoroethylene 10 units is also referred to hereinafter as "fluorineextra or Fextra".
It has been found in the course of development of the present invention that it is advantageous to have a certain amount of fluorine at the surface, with the fluorine in non-ETFE-bound form.
It is therefore preferable in accordance with the invention an ETFE film coated in accordance with the invention, wherein the ratio between the proportion of fluorine not bound in the form of tetrafluoroethylene units and the proportion of fluorine bound in the form of tetrafluoroethylene units at the surface of the coating here is 0.5, preferably 1, further preferably 2, greater compared to the interior of the ETFE film, is present.
The "interior of the ETFE film" in the context of this text is understood to mean the middle region of the ETFE film (without coating). For the avoidance of doubt, the value of the respective atomic concentration "in the interior of the ETFE film" should be determined in the middle of the ETFE film at right angles to its surface, it being preferable that the coating is not included for the determination of the respective middle. But since it is not easy in many cases to identify the specific boundary between coating and original film in the ETFE
film coated in accordance with the invention, for the avoidance of doubt, the thickness of the coating is not subtracted in the determination of the middle; in other words, the site for determination of the values in the "interior of the ETFE film" is the middle between the two surfaces of the coated ETFE film of the invention.
Preference is given in accordance with the invention to an ETFE film coated in accordance with the invention, wherein there is between 0.5 at% and 18 at%, preferably between 1 at%
and 15 at% and more preferably between 2 at% and 10 at% more fluorine not bound to Date Recue/Date Received 2021-05-21 tetrafluoroethylene units at the surface of the coating compared to the interior of the ETFE
film, based on the total number of atoms measured by XPS.
Especially when the coating material used is a non-fluorinated material (which is preferable in accordance with the invention), the above-described ratios of fluorine not bound to tetrafluoroethylene units or the absolute concentrations of fluorine not bound to tetrafluoroethylene units are a good indication that there is good or excellent adhesion of the coating on the originally uncoated ETFE film. This is because, if a suitable application method is chosen, parts of the ETFE units are chemically altered during the application method, especially in that fluorine or fluorinated molecular moieties are eliminated, such that binding of the coating to the original ETFE film is promoted. Without being tied to any theory, the fluorinated molecular moieties interact with the medium to be deposited during the layer application, are thus deposited as well and form a particularly thermally adhering mixed layer. This is the case especially when the application methods are plasma methods or methods with a radiation component having wavelengths < 250 nm, preferably 200 nm.
It is preferable in accordance with the invention that the coated ETFE film of the invention comprises fluorine (F), oxygen (0), and carbon (C) in the coating. It is particularly preferable that the coating for use in accordance with the invention consists to an extent of 95% of the elements silicon, aluminum, zinc, titanium, oxygen, carbon, fluorine and hydrogen, further preferably to an extent of 98 atom%, in each case measured by XPS.
The ETFE film surface coated in accordance with the invention, measured by XPS, preferably has the following element composition on the coating side (recording angle 0 , i.e. orthogonally to the sample surface or 0 to the surface normal):
5 at% < [Coo] <25 at%
35 at% < [000] <60 at%
18 at% < [Sic)] <30 at%
2 at% < [Foo] < 30 at%, based in each case on the total number of atoms detected by XPS.
The ETFE film surface coated in accordance with the invention further preferably has, on the coating side, measured by XPS, preferably the following element composition at recording angle 0 , i.e. orthogonally to the sample surface or 0 to the surface normal:
10 at% < [Coo] <20 at% and/or 45 at% < [000] < 50 at% and/or Date Recue/Date Received 2021-05-21

-6-20 at% < [Sio.] <27 at% and/or at% < [Foo] <20 at%, based in each case on the total number of atoms detected by XPS, more preferably with an "and" linkage of the preferred ranges in all cases.
The concentration of fluorine [Fextra] not bound in the form of tetrafluoroethylene units is 5 .. calculated from the difference between the measured fluorine concentration of the coated ETFE film surface [Fo.] and the calculated fluorine concentration [FTFE] of the tetrafluoroethylene units of the ETFE at the surface. Without being tied to any theory, this species is produced by the action of the coating method, especially of a plasma or the corresponding radiation component, for example, on the ETFE film and/or through redeposition of fluorine during the layer deposition, and results in a transfer from the ETFE
film to the coating. In this transition region, there are concentration gradients that do not form a sharp interface but an interphase that enables particularly good adhesion of the coating on the ETFE film.
The concentration [Fextra] is preferably between 1 at% and 18 at%, more preferably between 3 at% and 15 at% and more preferably between 6 at% and 10 at%, based in each case on the total number of atoms detected by XPS.
[Fextra] = [F] - [FTFE]
The fluorine concentration [FTFE] is determined in that the high-resolution Cis spectrum is recorded, and the person skilled in the art, by baseline correction of the separated peak of the tetrafluoroethylene groups (02F4 groups) at EB = 289.85 eV +- 0.2 eV, determines the proportion of this Cis photoelectric line (CTFE content) of the overall Cis spectrum (in the case of normalization of the aliphatic Cis peak of the ethylene groups of the ETFE to 285.0 eV). The fluorine concentration FTFE is calculated as follows:
[FTFE] = 2 x [C] X CTFE content Preference is given in accordance with the invention to an ETFE film coated in accordance with the invention, wherein the coating has a concentration gradient for the concentration of fluorine not bound to tetrafluoroethylene units, wherein the concentration preferably decreases with depth.
This fluorine concentration gradient suggests a particularly suitable coating method, especially a plasma-polymeric coating method.
Date Recue/Date Received 2021-05-21

- 7 -Especially within the scope of the prerequisite that, during the coating of the ETFE surface, the coating is bound using a suitable application method (by chemical modification of the ETFE), preference is given to an ETFE film coated in accordance with the invention, wherein the coating has a concentration gradient for the concentration of the elements 0 and/or C and/or Si and/or Ti and/or Zn and/or Al, wherein, preferably, - the 0 concentration increases with depth and/or - the C concentration decreases with depth and/or - the Si concentration decreases with depth and/or - the Ti concentration decreases with depth and/or - the Zn concentration decreases with depth and/or - the Al concentration decreases with depth.
A concentration gradient is present in accordance with the invention when the XPS
measurements for a single element at the recording angle of 0 degrees (maximum penetration depth) and at the recording angle of 70 degrees (lower penetration depth =
closer to the surface) give different results.
The XPS measurements at a recording angle of 700 preferably give the following differences in concentration compared to the XPS measurements at a recording angle of 0 :
-0.5 at% < AO < 10 at% and/or -5 at% < AC <- 0.25 at% and/or -5 at% < ASi <- 0.25 at%, based in each case on the total number of atoms detected by XPS, with:
AO = [000] ¨ [07o]
ASi = [Sioc] ¨ ]
AC = [Coo] ¨ [C700]
Date Recue/Date Received 2021-05-21

- 8 -Therefore, A values < 0 mean a decrease in the concentration of the respective element with depth, and A values > 0 an increase in the concentration of the respective element with depth.
Preference is given in principle to an ETFE film coated in accordance with the invention, wherein the applied coating at the surface, measured by XPS, contains at least 0.5 at%
fluorine; preferably at least 1 at%, based on the total number of atoms measured by XPS.
It is preferable here that at least some of the fluorine at the surface of the coating is not in the form of tetrafluoroethylene units.
-5 at% < AFextra <- 0.25 at%, based in each case on the total number of atoms detected by XPS, with AFextra = [Fextra,0 ] - [Fextra,70 ].
These compositions of matter of the coating, especially those that are preferred, have good properties for the purposes of the objective.
By means of the compositions of matter described, especially by means of those that are preferred, it is also possible to create particularly good properties for the coated ETFE film of the invention.
Accordingly, preference is given in accordance with the invention to a coated ETFE film wherein the coating applied has a static contact angle with respect to water of 60 , preferably 50 , more preferably 40 .
Preference is also additionally given to an ETFE film coated in accordance with the invention, wherein the coating applied has a disperse component of surface energy in the range of 25-45 mN/m, preferably between 28-40 mN/m.
For the avoidance of doubt, the disperse component of surface energy is determined as in example 3 adduced.
Date Recue/Date Received 2021-05-21

- 9 -Preference is given to an ETFE film of the invention, wherein the coated ETFE
film compared to the uncoated ETFE film has a reduction in UV transparency in the wavelength range between 300 nm and 400 nm by less than 3%, more preferably less than 2%, further preferably less than 1%.
It is immediately comprehensible here that the above-describes features achievable in accordance with the invention are particularly advantageous for the use of the coated ETFE
film of the invention. It is easily possible for the person skilled in the art, on the basis of the present data, especially by means of the preferred compositions of matter, to achieve particularly favorable properties for the envisaged use within the technical framework defined by the invention.
It is particularly preferable within the context of the invention that the coating applied is a plasma-polymeric coating. Plasma polymers can be controlled particularly efficiently with regard to layer properties and have good variability by the person skilled in the art within the scope of the invention, especially on the basis of the data described further down in the examples. In principle, the coatings of the invention are also producible in other ways than plasma-polymeric coatings. But these are particularly readily available to the person skilled in the art.
Alternatively preferred coating methods for the production of the ETFE film coated in accordance with the invention, as well as plasma-polymeric coating (which is particularly preferred), are also application methods such as, for example, reactive sputtering of aluminum, zinc or titanium or oxides thereof. It is particularly preferable in these cases that the film is in the direct line of sight of the sputtering source and, further preferably, the distance between sputtering source and film is sufficiently small that the ETFE film is influenced by the plasma present and/or the high-energy radiation having wavelengths of preferably <250 nm, further preferably < 200 nm. The distance between sputtering source and film are preferably < 10 cm, further preferably < 5 cm, further preferably <2 cm, further preferably < 1 cm. For all application methods, it is particularly preferable in accordance with the invention that the coating material (i.e. the material which is applied to the ETFE
film) does not comprise any fluorine.
Preference is given to an ETFE film of the invention, wherein the coating applied, after heating to 90 C for 5 minutes and then cooling to room temperature, has a static water contact angle of 60 and/or a surface energy of 45 mN/m, further preferably 50 mN/m, more preferably 55 mN/m.
Date Recue/Date Received 2021-05-21

- 10 -It is particularly preferable here that the values given in the preceding paragraph for water contact angle and/or surface energy are also satisfied in the case of heating to 95 C, preferably to 100 C, further preferably to 105 C, even further preferably to 110 C, more preferably to 115 C and most preferably to 120 C for 5 minutes, followed by cooling to room temperature.
These properties are particularly important for many uses of the film of the invention, since it is frequently necessary to briefly heat the film in order to apply it to the target surface.
Transmittance at a wavelength of 400 nm in the case of the film of the invention at a film thickness of 100 pm is preferably at least 0.75, further preferably at least 0.80, and even further preferably at least 0.82, and preferably at most 0.95, further preferably at most 0.90, and even further preferably at most 0.87. The coating applied preferably has a layer thickness of less than 50 nm, more preferably less than 35 nm, further preferably less than 25 nm, more preferably less than 15 nm.
Also part of the invention is the use of an ETFE film coated in accordance with the invention for fitout, especially in the form of coating of built structures, preferably buildings, more preferably greenhouses.
Within the scope of the use of the invention as well, it is generally preferable that the ETFE
film to be used in accordance with the invention is one which, after heating until softened and subsequent cooling to room temperature, has shrinkage in at least one spatial direction of 0.5%, preferably 1%. This is helpful in order to apply the film as outer skin of a built structure (or in the case of greenhouses also as an inert coating) by means of a sufficient film tension. Surprisingly, the mechanical properties of these ETFE films to be used with preference correlate particularly well with those of the coating to the used in accordance with the invention.
Also part of the invention is a process for producing the coated ETFE film of the invention, comprising the steps of a) providing an ETFE film, preferably in a preferred variant described above, b) applying a coating as defined above, preferably likewise a preferred variant, to the ETFE
film.
Date Recue/Date Received 2021-05-21

-11 -As already described above, in this way, long-term stabilization is enabled, and this effect is also essentially unchanged preferably after brief heating of the film (cf.
further up) up to the heat deflection temperature (HOT-A) of the film.
Preference is given to a process of the invention wherein a plasma-polymeric coating is applied in step b), preferably with hexamethyldisiloxane (HDMSO) as precursor, and/or wherein plasma activation by means of oxygenous gases, preferably by means of oxygen, is preferably effected in a subsequent step c).
The plasma treatment process preferably consists of multiple process steps, more preferably including a coating step and a subsequent activation step; the coating step is preferably preceded by a process step for simultaneous drying and activation.
In general, for the preferred plasma process of the invention, in at least one process step (coating), a compound that forms layers under the action of plasma, preferably as a gas, is (also) introduced into the plasma chamber. This compound is preferably a silicon-containing compound, further preferably an organosilicon compound, even further preferably a compound selected from the group of silanes, siloxanes, silazanes, and most preferably HDMSO.
An alternatively preferred process of the invention is one wherein a Ti-containing and/or Al-containing and/or Zn-containing metal oxide layer is applied in step b), preferably by reactive gas sputtering, in which the ETFE film is in direct line of sight of the sputtering source and/or the distance between sputtering source and film is preferably <
10 cm, further preferably < 5 cm, further preferably < 2 cm, further preferably < 1 cm, and/or wherein, preferably, in a subsequent step c), plasma activation is effected by means of oxygenous gases, preferably by means of oxygen.
For the coating, the film is preferably moved across a plate electrode at least partly at a distance of at least 4 mm and at most 200 mm; where the film preferably has a width of at least 350 mm and the plate electrode is at least 5 mm wider than the width of the film.
Preference is given here to moving the fluoropolymer film across the electrode at a speed between 0.5 m/min and 150 m/min, more preferably between 1.5 m/min and 50 m/min.
In the coating operation, the film is preferably moved across a plate electrode for at least 0.3 m, more preferably at least 1 m, in web direction. In the coating operation, the film is more preferably moved across at least two plate electrodes having a total length (in web Date Recue/Date Received 2021-05-21

- 12 -direction) of at least 0.3 m, more preferably at least 1 m. The film is further preferably, at least before and/or after passing in front of the electrode at a distance of not more than 150 mm, guided within the plasma chamber for at least one meter (sheet length) at a distance of more than 250 mm away from the electrode.
The plate electrode is preferably a high-frequency plate electrode.
During the coating process, a self-BIAS of less than 50 V is preferably applied, more preferably of less than 30 V, further preferably of less than 10 V.
Preference is given to applying the coating in a roll-to-roll process in a low-pressure plasma reactor.
More preferably, the low-pressure plasma reactor is operated at pressures between 0.01 and 0.5 mbar, preferably between 0.02 and 0.1 mbar.
Immediately downstream of the plasma treatment process, the surface of the ETFE film preferably has a surface energy of 50 mN/m, preferably 60 mN/m, more preferably 68 mN/m (measured according to Owens Wendt with values from Rabel Kaelble).
The production processes of the invention that have been described, especially those that are preferred, make the film coated in accordance with the available economically and rapidly obtainable (producible) in high quality.
Alternatively preferably, it is possible to deposit metal oxide-containing, more preferably aluminum oxide-containing, titanium oxide-containing and/or zinc oxide-containing, coatings. For this purpose, the person skilled in the art makes use, for example, of PE-CVD
techniques or reactive sputtering techniques.
Examples Example 1: Measurement of film shrinkage:
The (untreated) film from example 5 is cut to size as a square with dimensions of ai=20 cm x bi=20 cm. 2 sides here are in extrusion direction, and 2 sides orthogonal thereto. This film is placed onto a piece of kitchen towel (ZEWA Wisch & Weg) in an oven.
The oven should be heated to 115 C beforehand. The film is left therein for 5 min.
After the film has Date Recue/Date Received 2021-05-21

- 13 -cooled to room temperature, the dimensions of the film (az and bz) are measured once again, and shrinkage is calculated as (al-a2)/ai or (bi-b2)/bi.
The ETFE film both with plasma coating for example 5 and without coating has a shrinkage of 1% in film web direction with a relative error of 12%.
Example 2: XPS measurement The XPS studies were effected with a Thermo K-Alpha K1102 system with an upstream argon glovebox for the handling of air-sensitive samples. Parameters:
recording angle for the photoelectrons 00 or 70 , monochromatized Al Ka excitation, constant analyzer energy mode (CAE) with pass energy 150 eV in overview spectra (step width 0.5 eV, 2 scans with a recording time of 9 min 4.2 sec.) and pass energy 40 eV in the spectra with high energy resolution (step width 0.05 eV, 10 scans with a recording time of 12 min 21 sec.).
Analysis area: diameter 0.40 mm. Electrically nonconductive samples are neutralized by a combination of low-energy electrons and low-energy argon ions. For compensation of charging effects, the main Cis photoemission line to be assigned to C-C/C-H
species is fixed at 285 eV; the positions of the further photometric lines thus move correspondingly.
Quantification is effected on the basis of documented relative sensitivity factors of the elements, taking account of the specific analyzer transmission function based on the assumption of a homogeneous distribution of the elements within the XPS
information depth (about 10 nm at a recording angle of the photoelectrons of 0 , or 3.5 nm at a recording angle of the photoelectrons of 70 ).
The detection limit of the method is element-specific and is about 0.1 at%.
Date Recue/Date Received 2021-05-21

- 14 -The XPS measurements on the film from example 5 result in the measurements listed in tables 1 and 2.
Table 1: Results of the XPS measurements [C] [0] [Si] [F]
(at%) (at%) (at%) (at%) ETFE film (uncoated) 0 degrees 46.8 0.3 0 52.9 ETFE film (coated) 0 degrees 15.8 47.8 22.7 13.8 ETFE film (coated) 70 degrees 17.8 43.6 24.9 13.8 Table 2: CTFE content calculated from the results of the XPS measurements:
CTFE [FIFE] [Fextra] [Fextrai/
content [FITE]
at% at%
ETFE film (uncoated) 0 degrees 0.498 46.6 6.3 0.13 ETFE film (coated) 0 degrees 0.183 5.8 8.0 1.39 ETFE film (coated) 70 degrees 0.095 3.4 10.4 3.08 Example 3: Measurement of surface energies Date Recue/Date Received 2021-05-21

- 15 -For the measurements of surface energy, a Mobile Surface Analyzer (MSA) from KrOss GmbH, Hamburg, was used. This is a contact angle measuring instrument in which two parallel droplets are dosed onto the sample surface with one click.
The test droplet is dosed contactlessly onto the sample surface at room temperature and has a volume of about 1 pl. 5 seconds after the droplet has been dosed, an image is made, and a static contact angle is first determined automatically by the "Sessile droplet (duplicate)" method. The automatic evaluation of the images is checked visually later and, if appropriate, the baseline is manually corrected and unevaluable images are rejected.
In order to be able to better describe the surface properties of the film, measurements are made with the test liquids water and diiodomethane at at least ten locally different positions.
These are used to form the average.
Test liquids used are water (surface tension: 72.80 mN/m; disperse component:
21.80 mN/m; polar component: 51.00 mN/m) and diiodomethane (surface tension:
50.80 mN/m; disperse component: 50.80 mN/m; polar component: 0.00 mN/m). For the avoidance of doubt, the person skilled in the art will verify the surface energy of the test liquids, for example with a Wilhelmy balance, and always ensure that the test liquid is fresh and pure.
The measurement software used is the "Advance" program (Version 1.6.2Ø), from KrOss GmbH.
The surface energy with the disperse and polar components is evaluated according to Owens, Wendt, Rabel & Kaelble (OWRK). Contact angle is measured in accordance with DIN 55660.
Table 3: Results of contact angle measurements Diiodo- Disperse Polar Total surface Water methane component component energy ( ) (mN/m) (mN/m) (mN/m) direct 99 75.2 20 2.0 22.0 Date Recue/Date Received 2021-05-21

- 16 -Untreated ETFE after storage at 95 72 22 3.1 24.7 film 115 C for 5 min Inventive film direct 32 43.4 37.8 28.8 66.6 according to ________________________________________________ example 5, measured 8 days after the coating then stored at 46.9 48.5 35.1 22.1 57.2 90 C for 5 min process (stored under laboratory conditions) Table 4: Results of contact angle measurements Diiodo- Disperse Polar Total Water surface methane component component energy (0) (0) (mN/m) (mN/m) (mN/m) direct 24.5 55.8 30.9 37.3 68.2 Inventive 30 s stored at 32.3 62.7 27.1 36.1 63.2 film 105 C
according 60s 34.4 57.5 30 32.8 62.8 to 10 s 33.4 57.8 29.8 33.6 63.4 example 5, 30 s stored at34.8 66.5 24.8 36.3 61.1 measured 60s 37.7 60.1 28.5 31.9 60.4 3 days 10 s 36.4 57.4 30 31.9 61.9 after the 30s stored at 39.7 54.5 31.7 28.4 60.2 coating 60s 125 C 34.5 62 27.4 34.5 62 process 10 s 41.1 54.3 31.8 27.6 59.4 (stored 30 s stored at 50.8 60 28.6 23.4 52 under 60s 150 C 50.2 59.2 29.1 23.4 52.4 laboratory 10 s 47.6 58.1 29.7 24.8 54.5 conditions) ___________________________ 30s storedC at 51.5 63.3 26.7 23.9 50.6 60s 73.4 70 22.9 11.9 34.9 As can be seen from the results in tables 3 and 4, the coating not only features a high surface energy, which is still clearly present even after heat treatment at 90 C for 5 minutes and at 125 C for one minute, but likewise features a high disperse component.
The disperse component in the case of organosilicon plasma-polymeric coatings is an indicator Date Recue/Date Received 2021-05-21

- 17 -of density and hence a high degree of crosslinking of the coating. These values additionally ensure full-area coverage of the film with the coating.
Layer integrity is unaffected by the film shrinkage associated with the heat treatment. The layer does not become detached and is wipe-resistant (dry, moderate manual pressure with a cotton cloth, wiped 5x in one direction).
Example 4: Wipe resistance For verification of wipe resistance, the ETFE film coated according to example 5 was wiped in one region 6x with moderate pressure using a quadruply folded profix all-purpose cloth.
By the naked eye, no change in the film surface was apparent. Subsequently, in this region, the MSA was used to make measurements of surface energy (see table 5). In addition, a 30 ml spray bottle with pump atomizer was used to spray deionized water onto the wiped region, and alongside it. In both cases, the deionized water did not show any tendency to form droplets ¨ a clear sign of an unchanged hydrophilic surface.
By way of comparison, a prior art film, the F-Clean film from AGC Chemicals Europe, Ltd.
was likewise wiped. Here, in the wiped region, clear wiping traces were apparent to the naked eye in the film surface. Subsequently, the surface energy of this wiped film was also examined with the MSA (see table 5). Here too, the 30 ml spray bottle with pump atomizer was likewise used to spray deionized water onto the wiped region, and alongside it. The deionized water clearly forms droplets in the wiped region, whereas no droplets are formed alongside ¨ a clear sign that the hydrophilic finish can be easily removed by wiping in the case of this film.
Date Recue/Date Received 2021-05-21

- 18 -Table 5: Results of contact angle measurements Diiodo- Disperse Polar Total surface Water methane component component energy ( ) ( ) (mN/m) (mN/m) (mN/m) Inventive film according to After wiping example 5 (6 days 58.5 57.3 30.1 18.1 48.2 6x with a after the coating folded all- process) purpose ________________________________________________________ cloth F-Clean film (prior 87.8 52.7 32.6 2.7 35.3 art) The results of these studies show that the film of the invention has a wipe-resistant hydrophilic finish. By contrast, the hydrophilic finish of the prior art film examined can be wiped off.
Example 5: Coating process An ethylene-tetrafluoroethylene copolymer film (ETFE; manufacturer: P.A.T.I, S.p.A, product: effect) of thickness 100 pm was coated in a roll-to-roll process in a cuboidal low-pressure plasma reactor having a volume of 15 m3 and a grounded stainless steel chamber wall. The lateral walls of the system are provided with water-cooled, two-dimensional high-frequency electrodes. During the roll-to-roll winding, the film is moved past this at a distance of 40 mm. The length of this region is 1650 mm per chamber side in film winding direction.
The route chosen here for the web ensures the same side of the film faces the electrode on both sides of the system.
In the above-described 40 mm region, the gap that forms with the film results in a particularly intense discharge, which is visually perceptible by a distinctly brighter plasma.
Aside from these intense discharge regions in front of the electrodes, the film is exposed in a less significant spatial plasma discharge during the roll-to-roll winding process.
Accordingly, plasma effects also take place here, especially since the free exposed material length totals 14.3 m.
Date Recue/Date Received 2021-05-21

- 19 -The system is designed such that the high-frequency power can be engaged in full without significant reflection of power in the reverse direction.
As described in table 6, the film was dried in the first step by roll-to-roll winding under reduced pressure, plasma-coated in the 2nd step and plasma-activated in the 3rd step.
The film in the form of a 1000 mm-wide web was alternately rolled back and forth from an unwinding roll to a winding roll in three completely successive steps.
The surface described in the examples always relates to the respective side of the film facing the electrode on the route of the web.
Table 6: Process parameters Step 1 Step 2 Step 3 Web speed (m/min) 6 3.5 7.5 HMDSO (sccm) - 50 Gas supply 02 (sccm) 200 1500 1000 Power (W) 400 7000 7000 Pressure (mbar) 0.030 0.040 0.040 Self-BIAS (V) 0 5 5 Example 6: UV-VIS measurements The instrument used is a Specord 210plus from analytikjena. A wavelength resolution of 1 nm was employed.
The transmission spectra of the uncoated ETFE film, the coated ETFE film according to example Sand the F-Clean film were recorded in the UV-VIS region with a Specord 210plus twin-beam instrument from Analytik Jena. The films were analyzed against air as reference in the wavelength range from 200 nm to 800 nm. measured.
Date Recue/Date Received 2021-05-21

- 20 -The spectra are shown in figure 1.
It is apparent here that the coated ETFE film according to example 5 has almost the same transmission as the uncoated film, whereas the spectrum of the F-Clean film has distinctly lower transmission.
The coated ETFE film, compared to the uncoated ETFE film, has a maximum reduction in transmittance of 1% in the range between 280 and 800 nm.
Date Recue/Date Received 2021-05-21

Claims

Claims:

1. A coated ETFE film, wherein the static water contact angle at the surface of the coating is 600 and there is at least 1 at% silicon, 1 at% titanium, 1 at% zinc and/or 1 at%
aluminum at the surface of the coating, measured by XPS, based on the total number of atoms measured by XPS, with the proviso that if, among silicon, titanium, zinc and aluminum, only aluminum is included at the surface: between 1 at% and 18 at%, preferably between 3 at% and 15 at% and more preferably between 6 at% and 10 at% of fluorine not bound in the form of tetrafluoroethylene units is included at the surface of the coating, based on the total number of atoms measured by XPS.

2. The coated ETFE film as claimed in claim 1, wherein, irrespective of whether, among silicon, titanium, zinc and aluminum, only aluminum is included at the surface, between 1 at% and 18 at%, preferably between 3 at% and 15 at% and more preferably between 6 at% and 10 at% of fluorine not bound in the form of tetrafluoroethylene units is included at the surface of the coating, based on the total number of atoms measured by XPS.

3. The coated ETFE film as claimed in claim 1 or 2, wherein the ratio between the proportion of fluorine bound to tetrafluoroethylene units and the proportion of fluorine bound in the form of tetrafluoroethylene units at the surface of the coating is 0.5, preferably 1, further preferably 2, greater compared to the interior of the ETFE film.

4. The coated ETFE film as claimed in any of the preceding claims, wherein there is between 0.5 at% and 18 at%, preferably between 1 at% and 15 at% and more preferably between 2 at% and 10 at% more fluorine not bound in the form of tetrafluoroethylene units at the surface of the coating compared to the interior of the ETFE film, based on the total number of atoms measured by XPS.

5. The coated ETFE film as claimed in any of the preceding claims, wherein the coating comprises F, 0 and/or C.

6. The coated ETFE film as claimed in any of the preceding claims, wherein the coating has a concentration gradient for the concentration of fluorine not bound to tetrafluoroethylene units, wherein the concentration preferably decreases with depth.
Date Recue/Date Received 2021-05-21

7. The coated ETFE film as claimed in any of the preceding claims, wherein the coating has a concentration gradient for the concentration of the elements 0 and/or C
and/or Si and/or Ti and/or Zn and/or Al, wherein, preferably, - the 0 concentration increases with depth and/or - the C concentration decreases with depth and/or - the Si concentration decreases with depth and/or - the Ti concentration decreases with depth and/or - the Zn concentration decreases with depth and/or - the Al concentration decreases with depth.

8. The coated ETFE film as claimed in any of the preceding claims, wherein the coating applied has a static contact angle with respect to water of 55 , preferably 500, more preferably 40 .

9. The coated ETFE film as claimed in any of the preceding claims, wherein the coating applied has a disperse component of surface energy in the range of 25-45 mN/m, preferably between 28-40 mN/m.

10. The coated ETFE film as claimed in any of the preceding claims, wherein the coated ETFE film compared to the uncoated ETFE film has a reduction in UV
transparency in the wavelength range between 300 nm and 400 nm by less than 3%, more preferably less than 2%, further preferably less than 1%.

11. The coated ETFE film as claimed in any of the preceding claims, wherein the coating applied is a plasma-polymeric coating.

12. The coated ETFE film as claimed in any of the preceding claims, wherein the coating applied has a layer thickness of 50 nm, preferably 35 nm, more preferably 25 nm, further preferably 15 nm.
Date Recue/Date Received 2021-05-21

13. The coated ETFE film as claimed in any of the preceding claims, wherein the coating applied, after heating to 90 C for 5 minutes and then cooling to room temperature, has a static water contact angle of 60 and/or a surface energy of 45 mN/m, further preferably 50 mN/m, more preferably 55 mN/m.

14. The coated ETFE film as claimed in claim 13, wherein the values for the water contact angle and/or surface energy are also satisfied in the case of heating to 95 C, preferably to 100 C, further preferably to 105 C, even further preferably to 110 C, more preferably to 115 C and most preferably to 120 C for 5 minutes and then cooling to room temperature.

15. The use of a coated ETFE film as claimed in any of the preceding claims for the fitout of built structures, preferably buildings, more preferably greenhouses.

16. A process for producing a coated ETFE film as claimed in any of claims 1 to 14, comprising the steps of:
a) providing a ETFE film, b) applying a coating as defined in any of claims 1 to 14.

17. The process as claimed in claim 16, wherein a plasma-polymeric coating is applied in step b), preferably with HDMSO as precursor, and/or wherein plasma activation by means of oxygenous gases, preferably by means of oxygen, is preferably effected in a subsequent step c).

18. The process as claimed in claim 16, wherein a Ti-containing and/or Al-containing and/or Zn-containing metal oxide layer is applied in step b), preferably by reactive gas sputtering, in which the ETFE film is in direct line of sight of the sputtering source and/or the distance between sputtering source and film is preferably < 10 cm, further preferably <
5 cm, further preferably < 2 cm, further preferably < 1 cm, and/or wherein, preferably, in a subsequent step c), plasma activation is effected by means of oxygenous gases, preferably by means of oxygen.

19. The process as claimed in claim 17 or 18, wherein, in step b), the ETFE film Date Recue/Date Received 2021-05-21 is moved at least partly, preferably completely, across a high-frequency plate electrode in a low-pressure plasma reactor at a distance of at least 4 mm and at most 200 mm, wherein the ETFE film preferably has a width of at least 350 mm and the plate electrode is at least 5 mm wider than the width of the ETFE film, wherein the ETFE film is moved across the electrode preferably at a speed between 0.5 m/min and 150 m/min, more preferably between 1.5 m/min and 50 m/min.

20. The process as claimed in any of claims 16 to 19, wherein step b) is performed in a roll-to-roll method, preferably in a low-pressure plasma reactor.
Date Recue/Date Received 2021-05-21