DE102013004925B4 - Substrates with anti-fog coating, associated manufacturing process, components or bodies and use of an amphiphilic substance - Google Patents

Abstract

Method for producing a substrate (1) coated on at least parts of a surface (4), wherein the coating (2) is a polymer paint coating having an anti-fog effect, characterized in that a composition is used for the coating (2) which a) the Basic component (s) of the polymer varnish; and b) an anti-fogging additive, wherein the anti-fogging additive is at least one amphiphilic substance capable of forming micelles in the as yet uncured paint, which is used at a concentration in the composition which forms a micelle in the paint; whereby the coating (2) of the cured lacquer comprises nanopores (3, 3 ') which appear on the surface (5) of the coating (2) with mean diameters of 10 to 100 nm, the polymer lacquer comprising a polyurethane lacquer Polyacrylate varnish, a polycarbonate varnish, or an isocyanate crosslinked Hydroxyacrylatlack is.

Description

The invention relates to a method for producing a substrate coated on at least parts of its surface, wherein the coating is a polymer paint coating with an anti-fog effect, associated substrates having a polymer paint-based anti-fog coating applied to at least parts of a substrate surface, components and bodies comprising such substrates and the use of an amphiphilic substance in polymer paint systems.

It is known to change the surface properties of substrates by means of plastic coatings targeted. These plastic coatings are also referred to as paints or films. The coatings also referred to below as polymer lacquers or simply lacquers are often, after application, hardened coatings, which i.a. Epoxies, polyurethanes, polyacrylates, mixed systems such as isocyanate-cured hydroxy acrylates, polycarbonates and the like; Like. Can contain. Curing is usually thermal or by radiation.

The polymer coatings are applied as protective layers or to achieve certain surface properties of the substrate. The paints are very often provided with additives that influence the paint properties.

Essential fields of application are e.g. Scratch-resistant coatings on relatively soft plastics, such as polymethyl methacrylate, UV protection coatings and anti-fog coatings, for example for instrument covers, cabinets, vehicle windows and much more.

The DE 33 23 684 A1 discloses, for example, a thin abrasion-resistant polyurethane coating for transparent substrates which is said to be resistant to oxidation and hydrolysis. For the polyurethane coating, a low molecular weight polycarbonate diol is reacted with an aliphatic diisocyanate and cured.

The DE 38 87 483 T2 discloses a scratch-resistant and solvent-resistant polyurethane protective layer for windshields and safety glass in which the polyurethane coating is obtained from polyester triol prepolymers and linear polyols.

The EP 0 782 015 B1 discloses a coating for optical components that is simultaneously an anti-fogging and anti-reflection coating. The coating consists of a polyacrylate film and is intended for example for lenses, mirrors and prisms.

The DE 10 2005 052 738 A1 discloses an anti-fog coating for showcases, ie for transparent substrates. The coating consists of a polyurethane obtained with a blocked isocyanate.

The US 6,270,846 B1 discloses a porous silicon-based coating formed using a surfactant, a hydrophobic polymer, and inorganic or organic silicon compounds. A film resulting from the evaporation of a solvent is stabilized by calcination. The hydrophobic polymer and the surfactant are decomposed by the calcination.

The abovementioned coating systems have in common that the chemistry of the base coating essentially determines the surface properties. Antifogging layers are very often hydrophilized on their surface. They are characterized, for example, by having small amounts of water, e.g. from a freshly condensed drop, can quickly absorb and transport these amounts of water laterally. The single drop spreads quickly on the surface. The fogging of the substrate by droplet formation is thereby avoided.

The ability to absorb water is often in conflict with other outcomes, i. to reach surface properties. The anti-fogging layers should also be scratch-resistant in spite of this primary desired effect, should have good transparency and good adhesion to various substrates. Furthermore, one longs for long-term stability even in the presence of UV light and solvents, resistance to heat, cold and moisture, environmental compatibility, simple processes for coating and a low price.

The invention has for its object to provide a polymer paint for an anti-fog coating available that does not lose other positive properties of the paint base system in improving the anti-fog effect (Antifogwirkung) and in particular in the coating volume absorbs little water, ie has a low swelling capacity.

The object of the invention is achieved with a method according to claim 1 and a coated substrate according to claim 8 and with components and bodies according to claim 12 comprising the coated substrate. The new use of micelle-forming amphiphilic substances as anti-fogging additive is given in claim 13.

In order to be able to realize various properties simultaneously in the coating material, the invention makes use of the knowledge that this can be achieved advantageously with a "nanoheterogenic" material and a nanoheterogeneous surface. It is thereby possible for certain areas of the material to provide certain properties at the microscopic or submicroscopic level, while other such areas provide additional other properties. This will be explained in more detail below without the following theoretical considerations being binding

According to current knowledge, the aggregation of the anti-fogging additive according to the invention into micellar associates causes hydrophilic pores in the cured coating, including the surface thereof, to develop the anti-fog effect. As a result of the aggregation prior to paint curing, which is a spontaneous process with a sufficiently high additive concentration, the polymer paint to which the antifogging additive according to the invention has been added contains only a small amount of this additive and is characterized by its other properties, such as, for example, scratch resistance and adhesiveness. practically unaffected. Thus, nanoheterogeneity allows antifogging properties to be combined with otherwise less compatible other properties.

• a) die Grundkomponenten des Lacks, d.h. die für die Lackbildung bzw. die Beschichtungsmatrix erforderlichen Reaktionskomponenten,
• b) ein Antibeschlagadditiv in Form wenigstens einer zur Mizellbildung in den noch nicht gehärteten Grundkomponenten des Lacks befähigten amphiphilen Substanz, die bei dem Verfahren in einer Konzentration oberhalb der Mizellbildungskonzentration in der Zusammensetzung eingesetzt wird, um in dem Lack Mizellen auszubilden.

The composition for the coating of substrates with a polymer lacquer according to the invention contains at least:

• a) the basic components of the lacquer, ie the reaction components required for the lacquer formation or the coating matrix,
• b) an anti-fogging additive in the form of at least one amphiphilic substance capable of micellization in the uncured base components of the lacquer used in the process in a concentration above the micelle concentration in the composition to form micelles in the lacquer.

If a dispersion varnish is chosen as varnish, water is added in a) in which the varnish components are dispersed or emulsified.

Preferably, a single anti-fogging additive is present, however, several such additives of the group of the invention may be mixed.

The antifogging additive or the mixture according to the invention of the same antifogging additives of amphiphilic substances must be present in a concentration above the micelle concentration in the composition so that the micelles and thus in the cured coating, the pores are actually formed. The micelle formation concentration is either from the beginning, i. already exceeded in the initial composition or is exceeded during the formation of varnish before solidification, for example in water or solvent removal during curing.

According to the invention, the hardened lacquer coating obtained by the process has nanopores which appear on the surface of the coating with mean diameters of 10 to 100 nm.

The pore-forming aggregates of the amphiphilic substances according to the invention are referred to herein as micelles, although they may be more complex structures than simple surfactant micelles in aqueous solution. Without wishing to be bound by the mechanism of pore formation, it is presently believed that the micelles or aggregates of the antifog additive are inversely oriented (inverse micelles) such that the hydrophilic domains of the amphiphilic micelle forming substance (s) are substantially internal to the aggregate are oriented, while the hydrophobic portions or districts are oriented to the paint system. The micelles of the antifogging additive may be spherical or rod-shaped (columnar micelles, columnar micelles). Amphiphilic substances that elongated in the paint system Forming micelles are preferred for the anti-fogging additive. The apparent on the surface of the cured coating average diameter of these micelles is about 10 to 100 nm, preferably from 20 nm to 60 nm. In this case, a diameter is averaged from the possibly irregular cross section of the surface pore. This can be done for example by measuring the detectable with the scanning electron microscope pores. In the examples, the values determined were between a minimum of 10-20 nm and a maximum of 60-80 nm

As antifogging additives in the context of the invention, amphiphilic substances having molecular weights between 200 g / mol and 3000 g / mol, preferably between 200 g / mol and 2000 g / mol, are preferably used. Amphiphilic substances in this molecular weight range are capable of forming micelles of appropriate size to produce the desired nanopores, including discrete surface pores, in the final lacquer. It is particularly preferred that the relative weight fractions of the hydrophilic and hydrophobic regions per molecule be between 30:70 and 70:30, as this may favor the formation of elongated micelles.

As anti-fogging additives in the context of the invention are preferably one or more substances selected from the group: nonionic surfactants having molecular weights from 200 g / mol, in particular nonionic ethylene oxide surfactants, and nonionic block copolymers or block co-oligomers whose blocks preferably have ether or alcohol units used ,

In the case of nonionic block copolymers and block co-oligomers, those which have at least one polar block are preferred. The polar blocks may contain, for example, ethylene oxide units. In the block copolymers or block co-oligomers, the blocks may preferably consist of poly- or oligoether blocks or of poly- or oligo-alcohol blocks. As a suitable example polyoxyethylene block copolymers have been found, namely block copolymers of ethylene oxide and propylene oxide, for example commercially available under the trade name "Pluronic ^®" from BASF, Germany. Preferably, the average molecular weights (MW) of these substances are greater than or equal to 1000 g / mol and more preferably less than or equal to 3000 g / mol, in particular less than or equal to 2000 g / mol.

Also suitable are ethoxylate surfactants, preferably having an average molecular weight (MW) of about 200 g / mol to about 3000 g / mol, preferably up to about 2000 g / mol. These include, but are not limited to, alkylene oxides, alcohol ethoxylates and fatty alcohol ethoxylates, alkyl phenol ethoxylates, fatty acid ethoxylates, ester ethoxylates, and fatty acid ester ethoxylates. Furthermore, nonionic sugar surfactants can be used in the abovementioned molecular weight range. Suitable ethylene oxide surfactants are, in particular, those available from Dow Chemicals under the trade name "Tergitol ^™ ". These are currently preferred and have been used successfully in the examples.

Generally, however, all amphiphilic substances that form micelles in the desired basecoat system are suitable, preferably elongated or collumnar micelles. After curing, nanopores with diameters of up to 100 nm are formed at the position of the micelles. The person skilled in the art can therefore easily find suitable anti-fogging additives on his own.

As stated above, molecular weights in a range between about 200 and 2000 or up to 3000 g / mol are advantageous for the patterning process. Too small molecules tend to be unstable. If the molecules are too large, the micelle formation is kinetically inhibited. Furthermore, an approximately equal weight fraction of hydrophilic to hydrophobic regions is favorable for the formation of elongated micelles. Strongly asymmetric surfactants tend to form spherical micelles. However, it appears that the formation of elongated, i. elongated micelles on the networking of the pores and the removal of water (fogging) with the help of the new coating has a positive effect.

It is conceivable, but not mandatory, for the amphiphilic molecules to form inverse micelles, that is, micelles in which the hydrophilic phase lies inside. In principle, normal micelles are also capable of transporting water. The latter configuration would require that e.g. in the case of a polyurethane varnish on the wall of the PU matrix, which has a certain internal amphiphilia, hydrophilic groups are exposed. The water transport can in this case take place in the area between the micelle and the wall.

To ensure that the micelle formation concentration is safely exceeded, it is preferably provided that the antifog additive be present in a concentration of at least 20% by weight, more preferably at least 30% by weight and preferably up to 50% by weight, based on the coating layer mass (the sum of the weight of the organic coating-forming components and organic additives, without taking into account existing water and without consideration of any existing inorganic nanoparticles, such as silica nanoparticles) is present in the composition.

• a) Mischen der Zusammensetzung für die Beschichtung
• b) Aufbringen der Zusammensetzung auf eine zu beschichtende Oberfläche des Substrats durch eines der folgenden Beschichtungsverfahren, nämlich Fluten/Gießbeschichten, Spincoating (Rotationsbeschichtung, Aufschleudern), Sprühen, Rakeln oder Tauchen,
• c) Aushärten der aufgebrachten Beschichtung durch Strahlung oder Wärme,
• d) optional Waschen der Beschichtungsoberfläche.

The process according to the invention for producing a coating of the described composition on the substrate is characterized by the following steps:

• a) mixing the composition for the coating
• b) applying the composition to a surface of the substrate to be coated by one of the following coating methods, namely, flood / cast coating, spin coating (spin coating, spin coating), spraying, knife coating or dipping,
• c) curing the applied coating by radiation or heat,
• d) optionally washing the coating surface.

The curing temperatures and, associated therewith, the curing times are i.a. dependent on the coated substrate and its temperature resistance. Compared to the conditions for the basecoat systems, there are no significant changes due to the addition of the antifogging additive. In some embodiments, the scratch resistance can be reduced. On the other hand, the addition of the inorganic nanoparticles (e.g., silica nanoparticles) usually improves adhesion and long-term stability, as well as allowing coatability on several different substrates - e.g. PMMA, PC and glass - which is usually not possible with the basic system.

The described composition for the coating is applied to the substrate to form the coating. This is then allowed to rest on the substrate, dried, cured and / or irradiated, which primarily depends on the base polymer varnish chosen.

The antifog coating substrate of the present invention is coated on at least portions of one of its surfaces. That is, the substrate as a whole may be coated on all its surfaces (e.g., by dipping), it may be fully coated on a surface, e.g. on the outer surface of a disc (made for example by flooding or spraying) or it may be coated on parts of one of its surfaces (partial coating by spatially targeted application or after covering uncoated areas).

The coating is characterized by having nano-pores in the coating which is an anti-fogging polymer paint coating which appear on the surface of the coating with mean diameters of 10 to 100 nm, preferably 20 to 60 nm, as is has already been explained above in connection with the manufacturing process.

The coated substrate is preferably obtained by the described method.

The average molecular weight of the micelle-forming amphiphilic substance (s) should be at least (≥) 1000 g / mol for block copolymers, preferably containing ethylene oxide and / or propylene oxide blocks, and at least (≥) 200 g / mol for hydrocarbon-terminated oligoethylene oxides, to produce sufficiently large aggregates or micelles and thus to form sufficiently large pores in the range between 10 and 100 nm. The aggregate size is dependent on other molecular and structural parameters of the anti-fogging additive, but can be detected and adjusted by pore formation.

The coating system which is preferred for the invention is either a polyurethane varnish, a polyacrylate varnish, a polycarbonate varnish or a more complex varnish system, for example an isocyanate-crosslinked hydroxyacrylate varnish. In preferred embodiments of this invention, the paints are in the form of aqueous dispersion systems (dispersion paint, water-based).

For example, aqueous components for a 2-component polyurethane system (2K-PU) are commercially available. In this case one component forms the binder, which is dispersible by bound hydroxy groups and any surfactants added by the manufacturer. The other component is the crosslinker, preferably a polyisocyanate, to which surfactant stabilizers have also been added by the manufacturer. Binders and crosslinkers are dispersible or emulsifiable in water. During drying or curing, the reservoirs of binder and crosslinker move together as the water volatilizes. At this stage, the arrangement of the described micelles is expected. Furthermore, the binder and crosslinker areas run into one another and thus form the polymer matrix by chemical crosslinking. It is noteworthy that these known coatings, despite the presence of dispersion-stabilizing surfactants, do not form pores and have no anti-fogging effect from home. Only the integration of the According to the invention used amphiphilic substances, namely, inter alia, higher molecular weight surfactants, above their critical micelle concentration, resulting in the paint to pores, preferably elongated nanopores, which causes an excellent anti-fog effect.

In a development of the invention, the composition for producing the coating may comprise silicon dioxide particles as a further additive, preferably highly dispersed silicon dioxide having an average particle size of up to about 50 nm. In aqueous systems, the silica additive may be added as silica sol. Particularly advantageous is a stabilized silica sol, for example one with negative surface charges.

Preference is given here on its surface with chemically reactive groups modified silica nanoparticles or silsesquioxanes whose epoxy, hydroxy or amino groups are compatible with the polymer matrix or chemically react with the crosslinker of the matrix. Preferably, particles of optionally 15 to 40 nm are used, the surface of which is functionalized with epoxy groups - e.g. Bindzil C 301 or Bindzil C 401 from AkzoNobel, see also example part - or silsesquioxanes are used whose up to eight formulaic cube corners are functionalized with 3-aminopropyl groups.

The coating of the substrate after curing or drying, i. in the finished state, pores formed by the antifog additive in the varnish. It can be assumed that the aggregates or micelles from the antifogging additive are not exclusively present on the surface of the coating. However, they form identifiable pores under the scanning electron microscope, also referred to herein as surface pores. It is desired that the surface pores are individual pores; virtually no channels are visible on the surface, which is caused by the manufacturing process. Within the coating, the pores are at least partially connected, which causes the transport of the condensation water and ensures the anti-fog effect by lateral water transport. The surface pores of the invention are discrete, single nanopores.

The mean diameter of the pores, as defined above, is from 10 to 100 nm, preferably from 20 nm to 60 nm. The average diameter is an average diameter of the individual pore. In a paint coating different sized pores can be present next to each other. The individual pore diameters should be between the stated limits. It is sufficient if at least 90% of the pores have diameters which are within the stated limits.

The adhesion of the base coat is virtually unaffected by the pores, as these occur only isolated and localized.

The substrate, on the surface of which the coating is applied, may consist of glass, in particular of float glass, but also of plastic or ceramic, wherein for plastic polymethylmethacrylate (PMMA) and polycarbonate (PC) are preferred.

According to an additional aspect, the invention also includes components comprising the substrate according to the invention, e.g. B. anti-fog coated mirrors in mirror mounts, optical elements with coated substrates and the like. The coated substrate may also form a self-contained product, e.g. coated mirrors as such, coated glass moldings, window or vehicle windows, vehicle parts, lamp bodies and so on. Furthermore, the invention also encompasses products which are equipped with the coated substrates according to the invention. These include, for example, devices containing anti-fog coated cover glasses, optical apparatus with coated lenses or prisms, showcases, technical instruments and the like.

Components, bodies or products according to the invention can be, for example: spectacle lenses, cover glasses, lenses, prisms, light parts, motor vehicle parts, parts of refrigerators, housings, measuring devices, in particular in aviation, in motor vehicles and in the maritime sector.

Generally, the invention as described above includes the use of an amphiphilic substance as a micellar aggregation nanopore-forming antifog additive in polymeric paint systems.

In the following the invention will be explained in more detail by means of exemplary embodiments. These examples and tests are intended to be illustrative and to better understand the invention. The expert can find further embodiments with reference to the above description. The invention is not limited to the embodiments.

EXAMPLES

Various specimens were made and these were subjected to tests. For this purpose, several example coatings were applied to different substrates.

substrates

• – Glas, nämlich Floatglas
• – Polymethylmetacrylat (PMMA), hier Plexiglas^®
• – Polycarbonat (PC), hier Macrolon^®.

Disc-shaped substrates were used in each case (slide form). The substrates were made

• - Glass, namely float glass
• - Polymethylmethacrylate (PMMA), here Plexiglas ^®
• - Polycarbonate (PC), here Macrolon ^® .

All substrates were colorless transparent (crystal clear).

coatings

• 1.) Basiskomponenten für 2-Komponenten-Hydrolack von Bayer Material-Science, Leverkusen, Deutschland, nämlich Bayhydrol A XP2695, eine wasserverdünnbare, OH-funktionelle Polyacrylatdispersion, ca. 41 %ig in Wasser/1-Butoxy-2-Propanol, neutralisiert mit Triethanolamin/Dimethylethanolamin (3:1), zu vermischen mit Härterkomponente Desmodur N3900, Bayer MaterialScience, einem Hexamethylen-1,6-Diisocyanat Homopolymer.
• 2.) Mizellbildende Polymere: Pluronic L64, BASF, Ludwigshafen, DE, ein difunktionelles Blockcopolymer, das mit primären Hydroxylgruppen terminiert ist, nicht-ionisches Surfactant, mittleres Molekulargewicht 2900. Tergitol 15S-9, The Dow Chemical Company, USA, ein Oligoethylenglykol mit Kohlenwasserstoff-Terminierung und einem Molekulargewicht von 230–258 g mol^–1.
• 3.) Silicazusatz (optional, Rezepturbeispiele 1 und 3) Bindzil CC401, AkzoNobel, Schweden, eine neutrale wässrige Dispersion eines kolloidalen Siliciumdioxids mit ca. 37 % Feststoffgehalt. Das Silicasol ist sterisch stabilisiert und mit Epoxygruppen funktionalisiert. Das Siliciumdioxid liegt in diskreten Partikeln vor, die mittlere Partikelgröße beträgt 12 nm.
• 4.) Demineralisiertes Wasser

Rezepturen für die Beschichtungen Rezepturbeispiel 1 Ansatz Lackschichtmasse (ohne Wasser) Komponente g Gew.-% Feststoffgehalt g Gew.-% Pluronic L64 4,54 16,6 1 4,54 38,3 Demineralisiertes Wasser 8,15 29,9 - - - Bayhydrol A 2695 5,75 21,1 0,43 2,47 20,9 Desmodur N3900 2,48 9,1 1 2,48 20,9 Bindzil CC401 6,35 23,3 0,37 2,35 19,8 Rezepturbeispiel 2 Ansatz Lackschichtmasse (ohne Wasser) Komponente g Gew.-% Feststoffgehalt g Gew.-% Pluronic L64 4,54 22 1 4,54 48 Demineralisiertes Wasser 8,15 39 - - - Bayhydrol A 2695 5,75 27 0,43 2,47 26 Desmodur N3900 2,48 12 1 2,48 26 Rezepturbeispiel 3 Ansatz Lackschichtmasse (ohne Wasser) Komponente g Gew.-% Feststoffgehalt g Gew.-% Tergitol 15S-9 4,05 15 1 4,05 34 Demineralisiertes Wasser 7,77 28,7 - - - Bayhydrol A 2695 6,25 23 0,43 2,69 23 Desmodur N3900 2,7 10 1 2,7 23 Bindzil CC401 6,3 23,3 37 2,33 20 Rezepturbeispiel 4 Ansatz Lackschichtmasse (ohne Wasser) Komponente g Gew.-% Feststoffgehalt g Gew.-% Tergitol 15S-9 4,05 15 1 4,05 43 Demineralisiertes Wasser 7,77 28,7 - - - Bayhydrol A 2695 6,25 23 0,43 2,69 28 Desmodur N3900 2,7 10 1 2,7 29 The example compositions used for coating contain the following chemical components:

• 1.) Base components for 2-component hydro lacquer from Bayer Material Science, Leverkusen, Germany, namely Bayhydrol A XP2695, a water-dilutable, OH-functional polyacrylate dispersion, about 41% in water / 1-butoxy-2-propanol, neutralized with triethanolamine / dimethylethanolamine (3: 1), to be mixed with hardener component Desmodur N3900, Bayer MaterialScience, a hexamethylene-1,6-diisocyanate homopolymer.
• 2.) Micellar Polymers: Pluronic L64, BASF, Ludwigshafen, DE, a difunctional block copolymer terminated with primary hydroxyl groups, nonionic surfactant, average molecular weight 2900. Tergitol 15S-9, The Dow Chemical Company, USA, an oligoethylene glycol with Hydrocarbon termination and a molecular weight of 230-258 g mol ^-1 .
• 3.) Silica additive (optional, Formulation examples 1 and 3) Bindzil CC401, AkzoNobel, Sweden, a neutral aqueous dispersion of colloidal silica containing about 37% solids. The silica sol is sterically stabilized and functionalized with epoxy groups. The silica is present in discrete particles, the average particle size is 12 nm.
• 4.) Demineralized water

Formulations for the coatings Formulation example 1 approach Lackschichtmasse (without water) component G Wt .-% Solids content G Wt .-% Pluronic L64 4.54 16.6 1 4.54 38.3 Demineralised water 8.15 29.9 - - - Bayhydrol A 2695 5.75 21.1 0.43 2.47 20.9 Desmodur N3900 2.48 9.1 1 2.48 20.9 Bindzil CC401 6.35 23.3 0.37 2.35 19.8 Formulation example 2 approach Lackschichtmasse (without water) component G Wt .-% Solids content G Wt .-% Pluronic L64 4.54 22 1 4.54 48 Demineralised water 8.15 39 - - - Bayhydrol A 2695 5.75 27 0.43 2.47 26 Desmodur N3900 2.48 12 1 2.48 26 Formulation example 3 approach Lackschichtmasse (without water) component G Wt .-% Solids content G Wt .-% Tergitol 15S-9 4.05 15 1 4.05 34 Demineralised water 7.77 28.7 - - - Bayhydrol A 2695 6.25 23 0.43 2.69 23 Desmodur N3900 2.7 10 1 2.7 23 Bindzil CC401 6.3 23.3 37 2.33 20 Formulation example 4 approach Lackschichtmasse (without water) component G Wt .-% Solids content G Wt .-% Tergitol 15S-9 4.05 15 1 4.05 43 Demineralised water 7.77 28.7 - - - Bayhydrol A 2695 6.25 23 0.43 2.69 28 Desmodur N3900 2.7 10 1 2.7 29

Production of the coatings

The three different substrates were flooded (cast coated) or alternatively spun (spin coated) with the formulations of the two example formulations and oven baked at 60 ° C for 17 hours. After cooling, various tests were performed on the six specimens.

Appearance of samples and test results

The samples had a macroscopically smooth surface. The additive does not appear to have any influence on the quality of the paint surface.

The coatings adhered to all three substrates chosen. This can not be achieved with conventional anti-fog varnishes, since these are substrate-specific.

The following table shows the test results for various property tests detailed below. These were each tested on various commercial paints and two paints according to the invention. It was coated by flooding. In the case of spincoating, corresponding results were obtained, except that the hardness depended on the coating thickness. In addition, the transparency was influenced by the coating process (see below). 3 u. 4 .). Table 1: Test results Scratch resistance adhesion Stability and impact on AF Transmission improvement paint ISO 15184 Gt KKT KWT DWT leaching ΔT ¹⁾ Visgard 2 B 0/5 sufficient Good Good - up to 1% NOF 3B 0/5 Good inadequate Good - 0% AFG 9B, HB 0/5 adequate, good Good Good - up to 1% Recipe 2 4B 0/5 Good very well Good Good up to 3.3% Recipe 4 B 0/5 Good very well Good sufficient up to 3.3% 1) average transmission increase in the range 425-705 nm compared to the substrate GT: cross-hatch test; KKT: climate constant test; KWT: climate change test; DWT: continuous heat test

Compare coatings:

• Visgard

  = Visgard 106-94, FSI, USA, used for coating polycarbonate; PU-based paint, order: spincoating;

  NOF

  = NOF 9700, Marubeni, JP, for the coating of PMMA; PU-based paint, order: spincoating;

  AFG

  = AFG 64 and AFPC 64, GXC Coatings, DE, for the coating of glass or PC; Sol-gel lacquer with polyurethane alcohols according to Pat. DE 10 2005040046 , Order: flooded

Paints according to the invention:

• Example recipe 2, order: flooded;
• Example recipe 4, order: flooded.

Testing

1. Scratch resistance

• a.) die Bleistifthärte nach ISO15184 (Ergebnisse in Tab. 1) sowie
• b.) durch leichtes Reiben mit Stahlwolle der Stärke 000 bestimmt. Keines der geprüften Muster war bei Reiben mit Stahlwolle beständig.

The scratch resistance was over

• a.) the pencil hardness according to ISO15184 (results in Tab. 1) as well as
• b.) by light rubbing with steel wool of the strength 000. None of the samples tested was resistant to rubbing with steel wool.

2. Adhesion

The adhesion to the substrate was determined by a cross-cut test as follows. After a cross-hatch, the injured area was examined with the magnifying glass and classified (first value of the value pair: 0 = perfect, 5 = area-dependent detachment in the intersection area). Thereafter, an adhesive tape was pressed onto the interface and then peeled off. Thereupon it was repeatedly examined and classified with a magnifying glass (second value of the value pair: 5 = perfect, 0 = areal detachment in the cutting area). After the cross-cut test, the samples were stored for 7 days at 60 ° C. and maximum relative humidity (KKT, climate constant test). If the varnish layer did not subsequently dissipate with compressed air and if the result of the cross-cut test was 0/5, the substrate adhesion was considered to be perfect.

3. Stability and Effect on Antifog Property (AF)

• a.) Klimakonstanttest, KKT: Hierfür wurden die zugehörigen Proben 7 Tage bei 60 °C und maximaler relativer Luftfeuchte gelagert (Proben, die vorher betauten oder deren Lackfilme sich ablösten wurden nach täglicher Kontrolle vorzeitig entfernt). Hatten sich nach 7 Tagen keine Kondensattröpfchen auf der beschichteten Oberfläche gebildet, galt die Antibeschlagschicht als intakt. Hauchtest: Danach wurden die Proben wiederum 1 h bei 4 °C gelagert und unmittelbar danach behaucht. Die in der Tabelle 1 wiedergegebenen Wertungen wurden wie folgt festgelegt: zu keiner Zeit wird ein Beschlag beobachtet – Wertung „sehr gut“, der Beschlag verschwindet binnen 2 Sekunden nach Anhauchen – Wertung „gut“, der Beschlag verschwindet in der Regel, jedoch nicht reproduzierbar binnen 2 Sekunden – Wertung „ausreichend“, der Beschlag verschwindet erst nach mehr als 2 Sekunden – Wertung „mangelhaft“, Versagen der AF-Eigenschaft;
• b.) Klimawechseltest, KWT: Die zugehörigen Proben wurden im Wechsel 5 h bei –20 °C und 5 h bei +80 °C bei maximaler relativer Luftfeuchte gehalten, Gesamtdauer 5 Tage. Danach folgte der oben beschriebene Hauchtest;
• c.) Dauerwärmetest, DWT: Die zugehörigen Proben wurden bei PMMA-Substraten 7 Tage bei 80 °C und bei PC- und Glas-Substraten 7 Tage bei 120 °C gehalten. Danach folgte der oben beschriebene Hauchtest;
• d.) Leaching Die Tendenz zum Herauslösen von Antibeschlagadditiv, verbunden mit dem Verlust der Antibeschlagwirkung, wurde geprüft, indem die zugehörigen Proben 30 min in 50 °C warmes Ethanol getaucht wurden. Während dieser Zeit wurde für ausreichend Durchmischung gesorgt, indem mit einem Magnetrührstab gerührt wurde. Anschließend wurde der oben beschriebene Hauchtest durchgeführt.

For durability endurance tests were performed. The fresh test pieces (coated platelets) were first stored for 1 h at 4 ° C (refrigerator) and immediately afterwards breathed. In intact Anti-fog layers, the fog disappears in fractions of a second. All samples had very good anti-fog properties at the beginning of the durability tests. Thereafter, various resistance tests were carried out:

• a.) Klimakonstanttest, KKT: For this purpose, the associated samples were stored for 7 days at 60 ° C and maximum relative humidity (samples that were previously dewed or their paint films peel off were removed prematurely after daily inspection). If no condensate droplets had formed on the coated surface after 7 days, the anti-fogging layer was considered to be intact. Breath test: Thereafter, the samples were again stored for 1 h at 4 ° C and immediately afterwards breathed. The scores given in Table 1 were determined as follows: at no time is a fitting observed - rating "very good", the fitting disappears within 2 seconds after breather - scoring "good", the fitting disappears, as a rule, but not reproducibly within 2 seconds - rating "sufficient", the fog disappears after more than 2 seconds - rating "deficient", failure of the AF property;
• b.) Climate change test, KWT: The associated samples were alternately kept for 5 h at -20 ° C and 5 h at +80 ° C at maximum relative humidity, total duration 5 days. This was followed by the above-described breath test;
• c.) Continuous heat test, DWT: The associated samples were kept at 80 ° C. for 7 days for PMMA substrates and at 120 ° C. for 7 days for PC and glass substrates. This was followed by the above-described breath test;
• d.) Leaching The tendency to leach out of anti-fogging additive, coupled with the loss of anti-fogging effect, was tested by immersing the associated samples in 50 ° C ethanol for 30 minutes. During this time, sufficient mixing was provided by stirring with a magnetic stir bar. Subsequently, the above-described breath test was performed.

4. Hardness

In addition, the pendulum hardness was determined by König according to DIN 53 157. Depending on the layer thickness, the pendulum hardness is at least 30. For thin layers, such as those obtained by spin coating, the hardness of the substrate is also recorded, which results in higher (apparent) pendulum hardnesses.

The tabular data shows that the new anti-fog coatings offer great benefits, especially when used in humid climates, changing temperatures and high temperatures. In addition, the transmission is increased, while still good adhesion and scratch resistance of the samples according to the invention. Frequently, an improvement of the antireflection properties could be observed.

The appearance of the samples and the experimental results will be discussed with the help of the following figures. Show it:

1a A schematic diagram for a cross-sectional view through a coated substrate;

1b A schematic diagram for a top view of a coated substrate;

1c A plan view of the surface of a coated substrate as in FIG 1b which additionally contains silica nanoparticles;

2 - diagrams for the physical characterization of the samples;

3A -C - transmission curves, comparison of different coatings on: A-float glass, B-PC, C-PMMA;

4A -C - Transmission curves, comparison coated uncoated on: A-float glass, B-PC, C-PMMA.

1 shows schematically in cross-sectional view a substrate 1 with a coating 2 , this coating 2 pore 3 having. The coating 2 is here only on a part of the substrate 1 executed, namely on the substrate surface 4 , The substrate may be part of a part or body not shown in detail 10 be. The representation is not to scale. As by dashed lines within the coating layer 2 indicated, domains of the coating additive are present in the coating matrix, so the paint. The domains form a network of pores. When the pores 3 the surface 5 They are visible in the scanning electron micrograph (pores 3 ' ). The pores 3 . 3 ' cause the coating film to efficiently absorb water and over the pore system 3 . 3 ' transported away, without at the same time the matrix would have to be changed in their properties with respect to the water transport. The function of the water uptake is localized in the nanopores and the matrix can be adapted to other application properties, eg adhesion, scratch resistance and the like. Like., To be optimized. Because the pores 3 . 3 ' have a diameter of only a few nanometers, they affect the optical properties of the film, so the coating 2 , Not. It is believed that it is precisely the finely divided nanopores that are crucial for increasing the transmission of the anti-fogging layer.

1b shows a coated pattern as in 1a shown in plan view, ie in a view as would be obtained with the scanning electron microscope. The 100 nm scale indicates that the average diameter varies between about 10 and 100 nm. In other samples, fluctuation ranges were measured, for example, between 20 and 60 nm. The nanopores immediately absorb the water from small, newly formed drops and transport it laterally. Due to this mechanism, the drops dissolve. The anti-fog properties are very good. The matrix is not involved in the water absorption, which could be proven by low degree of swelling (see below).

1c shows a corresponding example as in 1b , only that in this example in the coating 2 additionally silica particles 6 are included. The silica particles are detected by scanning electron microscopy as very small bumps. The diameter of the silica particles used in the experiment was on average 12 nm. The silica particles therefore influence exclusively the coating properties, but not the macroscopic surface properties of the coating 2 ,

• 1. Proben (ohne Silicapartikel), die das Antibeschlagadditiv in einer Konzentration unterhalb der kritischen Mizellkonzentration enthielten, waren porenfrei mit glatter Oberfläche, das Material besaß jedoch eine nicht ausreichende Antibeschlagaktivität.
• 2. Ab einem größeren Gewichtsanteil des Antibeschlagadditivs, der oberhalb der kritischen Mizellkonzentration lag, werden einzelne Poren sichtbar und die Antibeschlagqualität der Beschichtung verbessert sich. Mit größer werdendem Gewichtsanteil des Antibeschlagsadditivs werden Poren erkennbar, die die Oberfläche durchstoßen, der Porendurchmesser liegt, sobald Oberflächenporen auftreten, bei den gemessenen Beispielen bei etwa 20 nm. Dies kann in Abhängigkeit von dem gewählten Additiv variieren.
• 3. Bei Proben, die zusätzlich Silica-Nanopartikel enthielten, erkennt man im Rasterelektronenmikroskop diese Partikel als zusätzliche kleine Erhebungen an der Oberfläche. Die Partikel führen zu einer Verbesserung mechanischer Eigenschaften wie Härte und Kratzfestigkeit und verbessern die Haftung des Lacks auf verschiedenen Substraten.
• 4. Auch bei Proben, die nachträglich gewaschen wurden, erkennt man die Oberflächenporen deutlich. Die Antibeschlag-Eigenschaft erweist sich demnach auch über längeren Gebrauch als stabil.

Further scanning electron microscopic investigations allow the following conclusion:

• 1. Samples (without silica particles) containing the antifogging additive at a concentration below the critical micelle concentration were non-porous with a smooth surface, but the material did not have adequate antifogging activity.
• 2. From a greater weight fraction of the anti-fogging additive, which was above the critical micelle concentration, individual pores are visible and the anti-fogging quality of the coating improves. As the level of anti-fogging additive increases in weight, pores are seen to puncture the surface, the pore diameter, once surface pores are encountered, is about 20 nm in the measured examples. This may vary depending on the additive selected.
• 3. For samples containing silica nanoparticles, these particles are detected in the scanning electron microscope as additional small elevations on the surface. The particles improve mechanical properties such as hardness and scratch resistance and improve the adhesion of the paint to various substrates.
• 4. Even with samples that have been washed afterwards, one recognizes the surface pores clearly. The anti-fogging property proves to be stable even after prolonged use.

2 shows results for the physical characterization of the samples. For this purpose, various tests were performed. 2A shows the contact angle "θ" for different samples. The two samples in the right section were measured on a conventional antifog coating (Visgard 106-94, Flexible Solution Inc., FSI, USA). It can be seen that the contact angles for the coatings according to the invention were not particularly small. This is due to the fact that the mechanism leading to the antifogging effect is different than in the case of coatings with a homogeneously hydrophilicized surface.

The contact angle measurement was made 1 second after applying a drop optically, that is, by the angle measurement on the drop after microscopic image pickup.

2 B shows the degree of swelling "Q" of the samples in air at 85% relative humidity. The degree of swelling was determined by weight measurement before and after contact with 85% relative humidity to constant weight. On the right the two measurements are again shown on conventional anti-fogging layers. As can be seen, the degree of swelling of the coatings according to the invention is comparatively low. This benefits other coating properties such as durability, adhesiveness, etc. 2C shows the apparent diffusion coefficient "D", determined from the swelling kinetics. The sample was transferred from a dry atmosphere to a humid atmosphere (85% relative humidity) at time t = 0 and then weighed time-dependently. The materials according to the invention have a higher apparent diffusivity for water than the comparative samples with less swelling in water. This is characteristic of the new coatings with nanoporosity and indicates the importance of the pores for the AF properties.

3 shows normalized transmission curves of the coated specimens against the substrate.

• – obere Kurve: konventionelle Beschichtung (AGF von GXC Coatings, DE),
• – im mittleren Wellenlängenbereich mittlere Kurve: erfindungsgemäße Beschichtung mit Tergitol als Antibeschlagadditiv (Beispielrezeptur 3)
• – im mittleren Bereich untere Kurve: erfindungsgemäße Beschichtung mit Pluronic als Antibeschlagadditiv (Beispielrezeptur 1)

3A shows the transmission curves for the substrate float glass. In each case, the transmission difference between coated and uncoated substrate at the same wavelength in percent specified.

• Upper curve: conventional coating (AGF from GXC Coatings, DE),
• Middle curve in the middle wavelength range: coating according to the invention with Tergitol as antifogging additive (example formulation 3)
• Middle curve lower curve: coating according to the invention with Pluronic as anti-fogging additive (example formulation 1)

• – untere Kurve: konventionelle Beschichtung (AFG, s.o.)
• – obere Kurven: erfindungsgemäße Beschichtungen mit Tergitol (Rzp. 3) und Pluronics (Rzp. 1).

3B shows the samples on polycarbonate substrates.

• Lower curve: conventional coating (AFG, see above)
• Upper curves: coatings according to the invention with Tergitol (Rzp. 3) and Pluronics (Rzp. 1).

• – untere Kurve: konventionelle Beschichtung (AFG, s.o.)
• – mittlere Kurve: erfindungsgemäße Beschichtung mit Pluronics (Rzp. 1)
• – obere Kurve, erfindungsgemäße Beschichtung mit Tergitol (Rzp. 3).

3C shows the samples on PMMA substrates

• Lower curve: conventional coating (AFG, see above)
• Middle curve: coating according to the invention with Pluronics (Rzp. 1)
• Upper curve, coating according to the invention with Tergitol (Rzp. 3).

4A C show transmission curves for differently prepared inventive coatings in comparison to the transmission of the pure substrate (curves a). In each case, a coating according to the recipe 1 was used, once flooded applied (curves b) and once spun (spin coated, curves c).

4A shows the results on a glass substrate. At short wavelengths, the transmission of the pure substrate is better than that of the coated substrates. Above 500 to 600 nm, however, the transmission of the coated substrates is even better than that of the pure substrate. The transmission of the flooded with the coating composition substrate is always slightly better than that of the spin coating coating.

4B shows the results for a polycarbonate substrate (PC). The same coating formulation was used as before. The flood-applied coating and those obtained by spin-coating are almost equally transparent and significantly more transparent than the uncoated substrate.

4C shows the results for a PMMA substrate. Again, the same coating formulation was used as before. The flood-applied coating shows approximately the same transmission values as the uncoated substrate, while the spin-coating coating shows slightly lower transmission values.

It can be seen that the coating process influences the transmission properties of the coated substrate. This must be taken into account when choosing the optimal process for the particular substrate and the application.

The experiments have shown that it is possible to achieve a material improvement in terms of simultaneous achievement of antifogging activity on the one hand and good adhesion to various substrates as well as transparency on the other when the coating is provided with nanopores as shown by the invention.

Surprising is the increase in transmission for most coating cases. It is believed to be an antireflective property due to nanopores.

Adhesion is mainly determined by the paint matrix but is not substantially affected by the additive. Due to the aggregation in the case of micelle formation, the anti-fogging additive barely dissolves in the paint matrix and accordingly does not change it. For the paint base, it was found that polyurethane paints or isocyanate-crosslinked acrylate paints are very advantageous in terms of their adhesion properties. They also have good strength as evidenced by wipe tests.

The UV resistance is determined by the base coat and of course hardly affected by pores. The same applies to solvent resistance and resistance to heat and cold.

Claims (16)

Method for producing at least parts of a surface ( 4 ) coated substrate ( 1 ), the coating ( 2 ) is a polymer paint coating with an anti-fog effect, characterized in that for the coating ( 2 ) a composition is used which contains a) the base component (s) of the polymer varnish and b) an anti-fogging additive, wherein the anti-fogging additive is at least one amphiphilic substance capable of micellising in the as yet uncured varnish, which is used in a concentration in the composition in which a micelle formation takes place in the lacquer, whereby the coating ( 2 ) from the cured lacquer nanopores ( 3 . 3 ' ), which at the surface ( 5 ) of the coating ( 2 ) having average diameters of 10 to 100 nm, the polymer coating being a polyurethane varnish, a polyacrylate varnish, a polycarbonate varnish, or an isocyanate-crosslinked hydroxyacrylate varnish. A method according to claim 1, characterized in that the polymer lacquer used is present as an aqueous dispersion system. Method according to claim 1 or 2, characterized in that the nanopores ( 3 ' ) appear on the surface with an average pore diameter of 20 to 60 nm. Method according to one of claims 1 to 3, characterized in that is used as the micelle-forming anti-fogging additive one or more substances selected from the group of nonionic surfactants having molecular weights from 200 g / mol. A method according to claim 4, characterized in that the group of nonionic surfactants comprises ethylene oxide surfactants and block copolymers or block co-oligomers, the blocks of which comprise ether or alcohol units. Method according to one of claims 1 to 5, characterized in that the anti-fogging additive from one or more amphiphilic substances in a total concentration of at least 30 wt .-%, based on the mass of the organic coating components including the organic additives is used. Method according to one of claims 1 to 6, characterized by the following steps: a) mixing of the composition for the coating ( 2 b) applying the composition to a surface to be coated ( 4 ) of the substrate ( 1 ) by one of the following coating methods - spraying - doctoring - flooding / cast coating - dipping, - spin-coating c) curing of the applied coating ( 2 by radiation or heat, d) optionally washing the coating surface. Coated substrate ( 1 ) with anti-fog effect, obtainable by the method according to one of claims 1 to 7. Coated substrate ( 1 ) according to claim 8, characterized in that the coating ( 2 ) contains silica particles as another additive. Coated substrate ( 1 ) according to claim 8 or 9, characterized in that the additive of silica particles is a highly dispersed silane-modified silica having an average particle size up to about 50 nm. Coated substrate ( 1 ) according to one of claims 8 to 10, characterized in that the substrate ( 1 ) consists of glass, plastic or ceramic. Component or body ( 10 ) containing the coated substrate ( 1 ) according to one of claims 8 to 11, namely a spectacle lens, a cover glass, a lens, a prism, a luminaire part, a motor vehicle part, a vehicle window, a window pane, a part of a refrigerator, a measuring device, a housing, a housing plate, a Showcase or a glass pane. Use of an amphiphilic substance in polymer coating systems rather than by micellar aggregation of nanopores ( 3 . 3 ' ) forming anti-fog additive. Use according to claim 13, characterized in that the amphiphilic substance is selected from the group of nonionic surfactants having molecular weights from 200 g / mol. Use according to claim 14, characterized in that the group of nonionic surfactants comprises ethylene oxide surfactants and block copolymers or block co-oligomers. Use according to claim 15, characterized in that the blocks of the block copolymers or block co-oligomers comprise ether, alcohol or ester units.

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