Multilayer barrier films, their preparation and use in photovoltaic applications

Abstract

The present invention relates to a multilayer barrier film for coating a transparent polymeric substrate (A), the multilayer barrier film (MLBF) comprising, in the order (B), (C), (D), one or more transparent at least partially inorganic barrier layers (B), one or more transparent radiation-cured (meth)acrylate layers (C), and one or more transparent thermally cured coating layers (D). The present invention further relates to substrates so coated, and to methods for producing MLBFs and MLBF-coated substrates. The present invention further relates to the use of MLBF-coated substrates in photovoltaic applications.

Description

[Technical Field]

[0001] The present invention relates to a multilayer barrier film (MLBF) for coating transparent polymeric substrates. The invention further relates to the substrates thus coated, and to methods for making the MLBF and the MLBF-coated substrates. Furthermore, the invention relates to the use of the MLBF-coated substrates in photovoltaic applications. [Background technology]

[0002] Polymer films are widely used and useful in a wide range of industrial and consumer applications. Such films can be used, for example, as clear or colored barrier films to protect various types of underlying substrates. Polymer films, particularly those made from semi-crystalline resins such as polyester materials, offer many desirable properties for barrier films. They exhibit, among other properties, transparency, flexibility, durability, toughness, softness, formability, lightweight, and affordable cost.

[0003] However, some of the most desirable polymeric films can be severely limited in their use in outdoor applications and other applications where the film is exposed to sources of light, moisture, and temperature for extended periods. For example, many polymeric films degrade when exposed to ultraviolet light for extended periods (which occurs naturally during outdoor use or by exposure to fluorescent or other UV-generating light sources) or when exposed to moisture at temperatures above their glass transition temperature.

[0004] CN109421334A discloses a barrier material comprising a polymer substrate, an alumina layer or silicon dioxide layer thereon, and a yellow light-absorbing radiation-cured layer thereon.However, such multilayer systems are not suitable for long-term outdoor applications, such as photovoltaic applications.

[0005] US10665738B2 provides a gas barrier film that can prevent damage to the inorganic layer even when used in products that undergo processes that apply pressure, heat, etc. US10665738B2 also relates to solar cells using the gas barrier film and a method for producing the gas barrier film. The inorganic film can be an aluminum oxide film formed by a vapor deposition method such as plasma CVD (e.g., capacitively coupled plasma (CCP)-chemical vapor deposition (CVD) and inductively coupled plasma (ICP)-CVD), sputtering (e.g., magnetron sputtering and reactive sputtering), or vacuum deposition. The protective layer formed on the inorganic film is a radiation-cured coating layer. However, even when intended for use in solar cells, the outer layer is not sufficiently resistant to long-term outdoor applications, as evidenced, for example, in DE102011113160A1, discussed in the following paragraph.

[0006] DE 102011113160 A1 discloses a polyurethane layer made of a hydroxyl-functional fluoropolymer cured with polyisocyanate and compares it with a radiation-cured coating layer. Both are applied directly onto a polymethyl methacrylate substrate. Thus, the fluoropolymer film is proposed as a more robust alternative to the radiation-cured coating film, but cannot be used in combination with this film. Furthermore, the construction, i.e., the layer order, of the barrier film disclosed in DE 102011113160 A1 is significantly different from the layer orders of CN 109421334 A and US 10665738 B2 mentioned above.

[0007] US2011 / 0045193A1 also discloses the use of a fluoropolymer-based layer in a barrier film. However, this document focuses on promoting adhesion of such a layer directly onto a backsheet substrate such as a polyester resin by incorporating boron nitride to promote adhesion. In the barrier film disclosed in US2011 / 0045193A1, a radiation-cured layer is neither mentioned nor envisioned. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] CN109421334A [Patent Document 2] US10665738B2 [Patent Document 3] DE102011113160A1 [Patent Document 4] US2011 / 0045193A1 Summary of the Invention [Problem to be solved by the invention]

[0009] There remains a clear need for an article containing a barrier film that combines improved light stability with higher moisture and gas barrier properties.There remains a need for an MLBF-coated substrate that is particularly stable for long periods in outdoor applications and exhibits good interlayer adhesion and reduced yellowing.Such an MLBF-coated substrate is suitable as a protective sheet for photovoltaic applications.

[0010] Due to its light weight, flexibility and advantageous cost, this type of protective sheet can be preferably used as a front protective sheet (front sheet) or a back protective sheet (back sheet) in applications such as solar cell modules, other possible applications include portable lighting devices, advanced packaging for optoelectronics, and displays such as OLED screens. [Means for solving the problem]

[0011] The above object of the present invention is achieved by providing a multilayer barrier film (MLBF) for coating a transparent polymer substrate (A), the multilayer barrier film comprising, in the order: (B), (C), and (D): one or more transparent, at least partially inorganic barrier layers (B), one or more transparent radiation-cured (meth)acrylate layers (C), and One or more clear, thermoset coating layers (D) Includes.

[0012] The term "for coating a transparent polymeric substrate" means that the multilayer barrier film is suitable for coating a transparent polymeric substrate, but is not limited to coating such substrates.

[0013] FIG. 1 shows a typical architecture of an MLBF on a substrate (A), which is further coated with an optional planarization layer (P).

[0014] The order of the three essential layers being (B), (C), (D) does not exclude the presence of additional layers preceding layer (B), following layer (D), and / or between layers (B) and (C) and between layers (C) and (D), respectively. In only those embodiments of the invention in which the multilayer barrier film consists of layers (B), (C), and (D), layer (C) is in direct contact with layers (B) and (D) as well as between layers (B) and (D).

[0015] The term "at least partially inorganic" with respect to the "at least partially inorganic barrier layer (B)" means that the layer(s) may be entirely composed of inorganic materials, but may also be composed of a preferably alternating sequence of inorganic and organic layers.

[0016] The term "radiation cured" with respect to the one or more transparent radiation-cured (meth)acrylate layers (C) refers to the radiation-curable nature of the crosslinkable monomers, oligomers and polymers used to prepare the radiation-cured (meth)acrylate layer, i.e., the presence of (meth)acrylic groups that react with each other to form the radiation-cured (meth)acrylate layer prior to curing, i.e., crosslinking. The term "(meth)acrylate" refers to both "acrylate" and "methacrylate."

[0017] The term "thermal curing" with respect to coating layer (D) refers to a curing mechanism that does not involve radiation, but rather involves a binder having reactive functional groups and a separate crosslinker having functional groups reactive with the functional groups of the binder.

[0018] The term "transparent" with respect to a layer and substrate means that the layer and / or substrate is translucent, i.e., light-transmitting. As used herein, the term "transparent" can be quantified by determining the total light transmittance according to ASTM D1003:2013. Preferably, the total light transmittance so determined is in the range of 80% to 99%, more preferably in the range of 85% to 98%, and most preferably in the range of 90% to 97%, for each layer of the MLBF, the MLBF itself, and the MLBF-coated substrates described below.

[0019] Hereinafter, the multilayer barrier film will also be referred to as the "multilayer barrier film of the present invention" or the "MLBF of the present invention."

[0020] Another object of the present invention is a multilayer barrier film coated substrate comprising, in that order, a transparent polymeric substrate (A), one or more transparent at least partially inorganic barrier layers (B), one or more transparent radiation-cured (meth)acrylate layers (C), and one or more transparent thermally cured outer coating layers (D).

[0021] Hereinafter, the multilayer barrier film-coated substrate will also be referred to as "the multilayer barrier film-coated substrate of the present invention" or "the MLBF-coated substrate of the present invention."

[0022] Yet another object of the present invention is to provide a method for producing a pharmaceutical composition comprising the steps of: a. providing a substrate; b. applying one or more inorganic layers onto the substrate by one or more methods selected from chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) and sputtering to form one or more transparent, at least partially inorganic barrier layers (B); c. applying one or more radiation-curable (meth)acrylic coating compositions C onto one or more transparent, at least partially inorganic barrier layers (B) to form one or more transparent, radiation-curable (meth)acrylate layers and curing the layer(s) to form one or more radiation-cured (meth)acrylate layers (C); and d. applying one or more thermosetting coating compositions D onto the one or more radiation-cured (meth)acrylate layers (C) to form one or more thermosetting coating layers D, and curing the layer(s) to form one or more clear thermosetting coating layers (D); Including, Additional steps between steps a. and b., steps b. and c., and steps c. and d. are not excluded. A method for producing a multilayer barrier film.

[0023] Hereinafter, the method for producing a multilayer barrier film will also be referred to as "the method for producing a multilayer barrier film of the present invention" or "the method for producing an MLBF of the present invention."

[0024] A further object of the present invention is a method for producing a multilayer barrier film coated substrate by providing a transparent polymer substrate (A) in a method for producing a multilayer barrier film according to the present invention.

[0025] Hereinafter, the method for producing a multilayer barrier film-coated substrate is also referred to as "the method for producing a multilayer barrier film-coated substrate of the present invention" or "the method for producing an MLBF-coated substrate of the present invention."

[0026] Yet another object of the present invention is the use of the inventive MLBF or the inventive MLBF coated substrate in photovoltaic applications.

[0027] Hereinafter, the method of using the MLBF of the present invention or the MLBF-coated substrate of the present invention in photovoltaic applications will also be referred to as the "method of use of the present invention."

[0028] Further preferred features and embodiments of the invention are disclosed in the dependent claims and the following detailed description. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 shows a typical configuration of an MLBF on a substrate (A), which is further coated with an optional planarizing layer (P). [Figure 2] FIG. 2 shows a possible "microconfiguration" of layer (B) when it consists of the layer stack (BiBo)n(Bi)t (n=2 and t=1, 0, respectively). [Figure 3] Figure 3 shows the MLBF configuration on the substrate. DETAILED DESCRIPTION OF THE INVENTION

[0030] Multilayer barrier film and substrate coated therewith As explained above, the multilayer barrier film of the present invention is suitable for coating transparent polymeric substrates, but is not limited to such substrates. Accordingly, various types of substrates that can be coated with the multilayer barrier film are disclosed below.

[0031] Base material The substrate can be any solid material, including, for example, metals, semi-metals, oxides, nitrides, and polymers. It is also possible for the substrate to be a mixture or composite of different materials.

[0032] However, polymers, and especially transparent polymers, are preferred as substrates.

[0033] Suitable polymers include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalene-dicarboxylic acid (PEN), polyimides, polyacrylates such as polymethyl methacrylate (PMMA), polyacrylamide, polycarbonates such as poly(bisphenol A carbonate), polyvinyl alcohol and its derivatives such as polyvinyl acetate or polyvinyl butyral, polyvinyl chloride, polyolefins including polycycloolefins such as polyethylene (PE), low density polyethylene (LDPE), linear low density polyethylene (LDPE), and the like. Examples of polymers include polyethylene (LLDPE), polypropylene (PP), and polynorbornene, polysulfones such as polysulfone (PSU), polyethersulfone (PES), and polyphenylenesulfone (PPSU), polyamides such as polycaprolactam (PA6) or poly(hexamethylene adipamide) (nylon 66), cellulose derivatives such as hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, methylhydroxypropyl cellulose, or nitrocellulose, polyurethanes, epoxy resins, melamine formaldehyde resins, phenol formaldehyde resins. The term "polymer" includes copolymers made of two or more different monomers, such as poly(ethylene-co-norbornene) or poly(ethylene-co-vinyl acetate).

[0034] Of the aforementioned polymers, transparent polymers from the group consisting of polyesters, polyolefins, polyamides and polysulfones are preferred, with polyesters such as PET being most preferred.

[0035] Preferably, the substrate, and in particular the polymeric substrate, should be heat stable to at least 140°C.

[0036] The substrate can have any size and shape. Preferably, the substrate, most preferably the polymer substrate, is in the form of a transparent film. Preferred film thicknesses are in the range of 10 to 500 μm, more preferably 25 to 300 μm, and even more preferably 50 to 150 μm.

[0037] Optional planarization layer (P) The surface of the substrate, particularly the substrate in the form of a transparent polymer film, is preferably highly flat.Highly flat in the context of the present invention means that the difference between the highest point on the surface and the lowest point on the surface is up to 100nm, preferably up to 50nm.Flatness can be measured, for example, by using an atomic force microscope, preferably in tapping mode.

[0038] Substrates often lack high flatness, for example, due to small scratches or particles such as dust adhering to the surface. Therefore, it is preferable to provide a planarizing layer (P) between the MLBF and the substrate to prevent damage such as punctures in the MLBF. The planarizing layer can also serve to better hold the substrate and the MLBF together, especially when bending or heating. Therefore, for the reasons mentioned above, the planarizing layer (P) can be present on the substrate even when planarization is not required. In such cases, the layer order is [substrate (A)]-(P)-(B)-(C)-(D), rather than [substrate (A)]-(B)-(C)-(D) as would be the case if no planarizing layer were applied.

[0039] Preferably, the planarizing layer (P) is made by depositing the material that constitutes the planarizing layer on the substrate before the MLBF is applied. When the planarizing layer is based on an organic polymer (which is preferred), it can be formed by applying a liquid organic coating composition to the substrate and then curing the layer thus formed, for example by heating or radiation, such as UV radiation. UV radiation is preferred. More preferably, the liquid organic coating composition used to produce the planarizing layer falls within the same definition as the liquid radiation-curable coating composition C used to form the transparent radiation-cured (meth)acrylate layer (C). In such cases, (P) can be identical to (C). In such cases, both layers (C) of the MLBF can be identical to or different from each other, as long as they fall within the definition of (C).

[0040] a transparent, at least partially inorganic barrier layer (B) The transparent, at least partially inorganic barrier layer (B) serves to provide the MLBF with good moisture barrier properties. The water vapor transmission rate (WVTR) at 40°C and 90% relative humidity is preferably 10 -3 g / m 2 / day, and even more preferably below 5 x 10 -4 g / m 2 / day.

[0041] As defined above, the term "at least partially inorganic" with respect to the "at least partially inorganic barrier layer(s) (B)" means that the layer(s) may be entirely composed of inorganic materials, but may also be composed of a preferably alternating sequence of inorganic and organic layers.

[0042] When layer (B) is composed of one or more inorganic layers, layer (B) is hereinafter referred to as (B i ) m In the formula, "i" represents "inorganic" and "m" represents the number of layers. Preferably, m is 1 to 2000, more preferably m=10 to 1000, and most preferably m=20 to 500.

[0043] When layer (B) further contains one or more organic layers in addition to one or more inorganic layers, layer (B) is hereinafter referred to as (B i B o ) n (B i ) t where "i" stands for "inorganic", "o" stands for "organic", and n stands for (B i B o ) the number of repeating layers, and t represents 1 or 0. The first layer of the barrier layer deposited on the substrate (A) or the optional planarization layer (P) is always the inorganic layer B i where the final layer in the stack can be either an inorganic layer (t=1) or an organic layer (t=0). The presence of such an organic layer between the inorganic layers provides additional flexibility to the barrier, especially when the MLBF has a thickness greater than 50 nm.

[0044] Figure 2 shows the layer (B) stack i B o ) n (B i ) t (n=2 and t=1, 0, respectively) for layer (B).

[0045] Inorganic layer(s) (B i The essential presence of ) in the at least partial inorganic barrier layer (B) contributes to the rollability and flexibility of the overall MLBF without the risk of compromising the water vapor transmission rate.

[0046] Inorganic layer(s) (B i ) can be achieved by several different techniques, e.g., chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) and / or sputtering, while the deposition of the organic layer(s) (B o The deposition of inorganic layers can be achieved, for example, by chemical vapor deposition (CVD), molecular layer deposition (MLD), organic (thermal or electron beam) deposition, wet coating deposition. Techniques such as PVD, CVD and sputtering for obtaining inorganic layers are known to those skilled in the art and are described, for example, in US 2013 / 0034689 A1 and EP 2692520 A1.

[0047] The inorganic material used to form the one or more inorganic layers is selected from the group consisting of metal oxides, metal nitrides, metal oxynitrides, and combinations thereof.

[0048] The most preferred inorganic materials for forming the inorganic layer are metal oxides, particularly metal oxides of aluminum, titanium, silicon, zinc, zirconium, hafnium, indium, tin, indium-tin, tantalum, and calcium, of which aluminum, silicon, and titanium are preferred oxide elements. In any of the embodiments described herein, it is particularly preferred to use metal oxides as the inorganic material for forming the inorganic layer(s).

[0049] It is further possible to use metal nitrides as inorganic materials. Among metal nitrides, the group of metal nitrides consisting of aluminum nitride, silicon nitride and boron nitride is preferred. The inorganic layer (B) on the substrate (A) and / or the planarizing layer (P) is preferably i The formation of a metal nitride layer as a barrier layer is preferably achieved by PE (plasma-enhanced)-CVD, CVD, ALD, or sputtering. Suitable techniques are described, for example, in WO2011028119. In particular, it is reported in the literature (W. Manders et al., AIMCAL R2R Conference, Florida, 2017) that a thin silicon nitride barrier layer produced by PE-CVD on a PET substrate has a thickness of 5×10 -4 g / m 2 It has been shown to have a WVTR of 1 / day.

[0050] Furthermore, metal oxynitrides can also be used as inorganic materials. Among metal oxynitrides, a group of metal oxynitrides consisting of aluminum oxynitride, silicon oxynitride, and boron oxynitride is preferred. The inorganic layer (B) on the substrate (A) and / or the planarizing layer (P) is preferably a metal oxynitride. i The formation of a metal oxynitride layer as a SiO 2 film is preferably achieved by PE (plasma-enhanced)-CVD, CVD, ALD, or sputtering. Suitable techniques are described, for example, in CN1899815B.

[0051] Inorganic layer (B i In (B), a combination of the above inorganic materials can be used. i ) m In the stacking of inorganic layers such as i ) may be independently selected from the inorganic materials described above, and (B i B o ) n (B i ) t and so on, with the values of m, n and t as given above.

[0052] Preferably, the layer thickness of the one or more at least partial inorganic barrier layers (B) is in the range of 10 to 1000 nm in total, more preferably in the range of 20 to 500 nm, and most preferably in the range of 30 to 200 nm.

[0053] Inorganic layer(s) (B i ), preferably a metal oxide layer (B i Among the aforementioned techniques for the deposition of (B) is preferred i ) m If (B) is (B i B o ) n (B i ) t In the case of ALD, it is ALD combined with MLD.

[0054] Transparent barrier layer (B i The use of ALD techniques for the preparation of the metal oxide layers (B) is preferred because ALD allows for the stepwise formation of highly conformal, well-ordered, and individually dense chemically bonded nanolaminate self-limiting layers with excellent thickness control. Such methods, especially for the preparation of metal oxide layers (B), are particularly advantageous. i ) are disclosed, for example, in WO2011 / 099858A1, but are also part of combined ALD / MLD techniques, as disclosed, for example, in WO2015 / 188990A2 and WO2015 / 188992A1.

[0055] An even more preferred transparent barrier layer is (B i B o ) n (B i ) t and layer(s) (B i ) is obtained by ALD, and the layer (B o ) are prepared by MLD. The combination of ALD and MLD techniques allows for molecular-level (a few nanometers thick) alternating deposition of organic flexibilizing layers deposited by covalent chemical bonding to inorganic materials, as disclosed, for example, in WO2015 / 188990A2 and WO2015 / 188992A1.

[0056] Layer (B o The organic molecules used in the MLD technique to obtain the inorganic layer (B ) can be, for example, as described in WO2015 / 030297A1, WO2015 / 188990A2 and WO2015 / 188992A1. i ), such as a thiol, disulfide, sulfide, selenol, amine, carboxylate, phosphate or phosphonate, or a derivative thereof.

[0057] Layer (B o The most preferred organic molecules for preparing the mercaptobenzoic acid (MERCAPTOBENZOIC ACID), mercaptophenol, aminomercaptophenol, and the like belong to the family of aromatic thiols. The scope of this organic molecule layer is to provide the brittle inorganic oxide barrier with the flexibility and bendability required for roll-to-roll processing (also known as web processing, reel-to-reel processing, or R2R), a process for creating electronic devices on rolls of flexible plastic.

[0058] Some further details regarding the preparation of the transparent, at least partially inorganic barrier layer(s) (B) are provided below under the section describing the method for preparing the MLBF of the present invention.

[0059] Transparent radiation-cured (meth)acrylate layer (C) As mentioned above, the term "radiation cured" with respect to the one or more transparent radiation-cured (meth)acrylate layers (C) refers to the radiation-curable nature of the crosslinkable monomers, oligomers, and polymers used to prepare the radiation-cured (meth)acrylate layer, i.e., the presence of (meth)acrylic groups on said species that react with each other to form the radiation-cured (meth)acrylate layer prior to curing, i.e., crosslinking. The term "(meth)acrylate" refers to both "acrylate" and "methacrylate," but preferably refers to "acrylate." The same applies to the use of the terms "(meth)acrylic" and "(meth)acrylic."

[0060] Thus, radiation curing is typically achieved by actinic radiation such as electron beam (EB) or UV radiation, with curing by UV radiation being particularly preferred.

[0061] Thus, the transparent radiation-cured (meth)acrylate layer(s) (C) are preferably based on a UV-curable solvent-free (meth)acrylic system. The term "solvent-free" means free from non-reactive solvents, although reactive diluents are not excluded by this term.

[0062] Preferably, the coating material used to prepare the transparent radiation-cured (meth)acrylate layer(s) (C) has a viscosity at 25°C, determined by capillary viscometer or rotational rheometer, before curing, of less than 500 mPas, most preferably less than 300 mPas.

[0063] The species used to form the one or more transparent radiation-cured (meth)acrylate layers (C) are preferably i. one or more radiation-curable oligomeric (meth)acrylate functional species; ii. one or more radiation-curable (meth)acrylate-functional monomers; iii. one or more adhesion promoters; iv. For UV curing, one or more photoinitiators; v. one or more compounds selected from UV absorbers, light stabilizers, and antioxidants, and vi. optionally one or more coating additives Includes.

[0064] Radiation-curable oligomeric (meth)acrylate functional species i. The one or more radiation-curable oligomeric (meth)acrylate functional species are preferably selected from the group consisting of polyester (meth)acrylates, epoxy (meth)acrylates, aliphatic and / or aromatic urethane (meth)acrylates, preferably aliphatic urethane (meth)acrylates, polyether (meth)acrylates and (meth)acrylated poly(meth)acrylates, of which urethane (meth)acrylates, epoxy (meth)acrylates and polyether (meth)acrylates are preferred.

[0065] Typically, the radiation-curable oligomeric (meth)acrylate functional species have a viscosity at 25°C of greater than 70 mPas.

[0066] Polyester (meth)acrylates typically have lower viscosities than other oligomers, while epoxy (meth)acrylates are highly reactive, and coatings obtained using them exhibit good hardness and chemical resistance. (Meth)acrylated poly(meth)acrylates are known for their good adhesion. Aromatic urethane (meth)acrylates provide coatings obtained using them with improved flexibility, elongation, and toughness, as well as good hardness and chemical resistance, and polyfunctional aromatic urethane (meth)acrylates exhibit improved reactivity. Aliphatic urethane (meth)acrylates exhibit similarly good properties to aromatic urethane (meth)acrylates, but tend to exhibit less undesirable yellowing.

[0067] The total amount of the one or more radiation-curable oligomeric (meth)acrylate functional species is preferably in the range of 5% to 30% by weight, most preferably 5% to 20% by weight, and even more preferably 5% to 15% by weight, based on the total weight of the radiation-curable coating composition C.

[0068] Radiation-curable (meth)acrylate-functional monomers ii. The one or more radiation-curable (meth)acrylate-functional monomers are known to those skilled in the art of radiation-curable compositions. Such radiation-curable (meth)acrylate-functional monomers have low viscosity, preferably 1 to 50 mPas, more preferably 2 to 40 mPas, or even 2 to 30 mPas at 25°C. They are also known as radiation-curable reactive diluents because they are used to dilute the radiation-curable oligomeric (meth)acrylate-functional species, acting as a solvent but remaining in the cured coating after curing. Such monomers may optionally contain dialkylene glycol or trialkylene glycol groups, but are still considered monomers herein due to their well-defined molecular weight and viscosity of less than 50 mPas at 25°C.

[0069] The (meth)acrylate functional monomers preferably used herein have a hydrophobic backbone and provide radiation-cured coating layers containing them with excellent adhesion to plastic and metal substrates, good chemical and water resistance, flexibility, and low emissions of volatile organic compounds.

[0070] The one or more (meth)acrylate functional monomers include mono(meth)acrylate functional monomers, di(meth)acrylate functional monomers, and tri-, tetra-, penta-, and hexa(meth)acrylate functional monomers, of which mono(meth)acrylate functional monomers and di(meth)acrylate functional monomers are most preferred.

[0071] Examples of mono(meth)acrylate functional monomers include hydrocarbyl esters of (meth)acrylic acid, where the hydrocarbyl residue may be aliphatic or aromatic, and linear, branched, or cyclic, preferably the hydrocarbyl group contains 4 to 20, more preferably 6 to 18 carbon atoms. Specific examples include alkyl (meth)acrylates such as cyclohexyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tert-octyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, aralkyl (meth)acrylates such as benzyl (meth)acrylate, and aryl (meth)acrylates such as 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, and 2,3,4,5-tetramethylphenyl (meth)acrylate. Further examples of mono(meth)acrylate functional monomers include ether oxygen-containing hydrocarbyl esters of (meth)acrylic acid, where the ether oxygen-containing hydrocarbyl residue may be aliphatic or aromatic and linear, branched, or cyclic, and preferably the ether oxygen-containing hydrocarbyl group contains 4 to 20, more preferably 6 to 18, carbon atoms. Specific examples include alkoxyalkyl (meth)acrylates such as butoxyethyl (meth)acrylate, butoxymethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, aryloxyalkyl (meth)acrylates such as phenoxymethyl (meth)acrylate and phenoxyethyl (meth)acrylate, 2-ethylhexyl diglycol (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, and trimethylolpropane formal (meth)acrylate.

[0072] Examples of di(meth)acrylate functional monomers are alkanediol di(meth)acrylates, where the alkanediol preferably contains 3 to 16 carbon atoms, more preferably 4 to 14. Specific examples include 1,3-propanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,7-heptanediol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, and 1,14-tetradecanediol di(meth)acrylate. Further examples of di(meth)acrylate functional monomers include dialkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate and dipropylene glycol di(meth)acrylate, trialkylene glycol (meth)acrylates such as triethylene glycol (meth)acrylate and tripropylene glycol di(meth)acrylate, and neopentyl glycol-propoxy di(meth)acrylate.

[0073] Less preferred are the following tri- to hexa(meth)acrylate functional monomers: The more highly functional the monomer in the present invention, the less preferred it is.

[0074] Specific examples of tri(meth)acrylate functional monomers include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, trimethylolpropane tris((meth)acryloyloxypropyl)ether, dipentaerythritol propionate tri(meth)acrylate, and tris((meth)acryloyloxyethyl)isocyanurate.

[0075] Specific examples of tetra(meth)acrylate functional monomers include pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol propionate tetra(meth)acrylate, and ethoxylated pentaerythritol tetra(meth)acrylate.

[0076] Specific examples of penta(meth)acrylate functional monomers include dipentaerythritol penta(meth)acrylate.

[0077] Specific examples of hexa(meth)acrylate functional monomers include, for example, dipentaerythritol hexa(meth)acrylate.

[0078] Preferably, the radiation curable composition of the present invention comprises only ii. mono(meth)acrylic monomers from the group of radiation curable (meth)acrylate functional monomers.

[0079] The total amount of the one or more radiation-curable (meth)acrylate-functional monomers preferably ranges from 10% to 90% by weight, most preferably from 15% to 85% by weight, and even more preferably from 20% to 80% by weight, based on the total weight of the radiation-curable coating composition.

[0080] Adhesion promoteriii. The one or more adhesion promoters are preferably selected from the group consisting of functionalized trialkoxysilanes and functionalized dialkoxyalkylsilanes, preferably functionalized trialkoxysilanes, such as functionalized trimethoxysilanes, and the functional groups are preferably selected from thiol groups, (meth)acrylic groups, amino groups and epoxy groups, and (meth)acrylated phosphate esters.

[0081] The total amount of the one or more adhesion promoters iii. is preferably in the range of 0.5% to 10% by weight, most preferably 1% to 8% by weight, and even more preferably 1.5% to 7% by weight, based on the total weight of the radiation curable coating composition.

[0082] Photoinitiators iv. For UV curing, preferably an alpha-cleavable photoinitiator is included, such as one or more photoinitiators selected from the group consisting of alpha-hydroxyketones (e.g., benzoin, acetophenone), alpha-alkoxyketones (e.g., benzoin ethers, benzil ketals), alpha-aminoketones, and acylphosphine oxides.

[0083] Photoinitiators can be encompassed by the terms "surface-cure type" such as alpha-alkoxyketones and "bulk-cure type" such as acylphosphine oxides. When both are present, the mass ratio of the photoinitiators between the surface-cure type and the bulk-cure type is preferably in the range of 1:4 to 1:1.

[0084] The total amount of the one or more photoinitiators iv., if present, preferably ranges from 0.5% to 6% by weight, most preferably from 2% to 5% by weight, and even more preferably from 3% to 4% by weight, based on the total weight of the radiation-curable coating composition.

[0085] UV absorbers, light stabilizers, antioxidants v. The UV absorber is preferably selected from the group consisting of 2-(2'-hydroxyphenyl)benzotriazole, 2-hydroxybenzophenone, esters of substituted and unsubstituted benzoic acid, acrylates such as ethyl alpha-cyano-beta,beta-diphenylacrylate, 2-(2-hydroxyphenyl)-1,3,5-triazine and oxamide.

[0086] The total amount of the one or more UV absorbers v. is preferably in the range of 1% to 5% by weight, more preferably 1.5 to 3.5% by weight, based on the total weight of the radiation curable coating composition.

[0087] The light stabilizer v is preferably a hindered amine light stabilizer (HALS), including NOR-HALS. NOR-HALS is a subclass of HALS, also known as aminoxyl radical hindered amine light stabilizers. HALS act as bases and are neutralized by acids, such as hydrochloric acid; NOR-HALS is not a strong base and is not deactivated by hydrochloric acid.

[0088] The total amount of the one or more light stabilizers v. is preferably in the range of 0.2 to 4% by weight, more preferably 0.5 to 3% by weight, and most preferably 0.8 to 2% by weight, based on the total weight of the radiation-curable coating composition.

[0089] The antioxidant v. is preferably tert-butyl hindered phenol and serves to improve long-term weather resistance and heat resistance.

[0090] The total amount of the one or more antioxidants v. is preferably in the range of 0.1% to 2% by weight, more preferably 0.2 to 1% by weight, based on the total weight of the radiation-curable coating composition.

[0091] Coating additivesvi. Coating composition C may contain typical coating additives such as leveling agents, antifoaming agents, etc., and is preferably, but not necessarily, reactive to radiation curing.

[0092] Thickness of the transparent radiation-cured (meth)acrylate layer (C) The final thickness of the transparent radiation-cured (meth)acrylate layer (C) is preferably in the range of 1 to 100 μm, more preferably 1 to 50 μm, and most preferably 5 to 30 μm. The coating materials applied to form the transparent radiation-cured (meth)acrylate layer(s) (C) can be applied by standard wet coating methods.

[0093] Transparent thermoset coating layer (D) The transparent thermoset coating layer (D) is preferably a transparent thermoset polyurethane coating layer (D).

[0094] The transparent, heat-cured coating layer (D) is characterized by excellent adhesion to the underlying transparent, radiation-cured (meth)acrylate layer (C) both before and after long-term aging under high and low temperature and humidity conditions.

[0095] The use of hydroxy-functionalized partially fluorinated reactive polymers is preferred in terms of light stability, flexibility, moisture resistance, chemical stability, and temperature stability, also taking into consideration their rapid reactivity with different types of curing agents. The transparent heat-cured coating layer (D) is preferably a polyurethane layer, and is preferably formed by reacting at least one hydroxyl-functional polymer selected from radically polymerized hydroxyl-functional fluoropolymers and hydroxyl-functional poly(meth)acrylates with a crosslinking agent, preferably one or more polyisocyanates, even more preferably one or more hydrophobic polyisocyanates.

[0096] Hydroxyl-functional polymers formed by radical polymerization The hydroxyl-functional polymer formed by radical polymerization and used to prepare the preferably transparent thermoset coating layer (D) is preferably selected from the group of radically polymerized hydroxyl-functional fluoro-containing polymers ("hydroxy-functional fluoropolymers") and hydroxy-functional poly(meth)acrylates. As used in this context, the term "polymer" includes "copolymer," and the term "copolymer" includes any polymer containing at least two different monomer units.

[0097] Preferably, the radically polymerized hydroxyl-functional fluoropolymer contains repeat units formed by polymerizing preferably one or more ethylenically unsaturated fluorine-containing monomers selected from the group consisting of vinyl fluoride FCH=CH2, vinylidene fluoride F2C=CH2, tetrafluoroethylene F2C=CF2, F2C=CF(OCF3), F2C=CF(CF3) and hexafluoropropylene, and mixtures thereof.

[0098] Other preferred monomers that may be used in combination with the above fluorine-containing monomers are, for example, ethylene, propylene, n-butene, isobutene, vinyl benzoate, and vinyl ethers, such as HC=CH-OR or HC=CH-CH-OR, where R is a linear, cyclic, and / or branched hydrocarbyl group, such as an alkyl group or a cycloalkyl group. Such groups R preferably contain 1 to 20, more preferably 2 to 16, e.g., 4 to 12, carbon atoms.

[0099] Because fluoropolymer contains hydroxyl group, it is necessary to use ethylenically unsaturated hydroxyl functional monomer in the radical polymerization of radically polymerized hydroxyl functional fluoropolymer.Examples of hydroxyl functional monomer include hydroxyl functional vinyl ether, such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2-methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether, hydroxyl functional allyl ether, such as 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether and glycerol monoallyl ether, or hydroxyalkyl ester of (meth)acrylic acid, such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.Among these, hydroxyl-containing vinyl ether, particularly 4-hydroxybutyl vinyl ether and 2-hydroxyethyl vinyl ether are particularly preferred.

[0100] Alternatively, the ethylenically unsaturated monomers can be modified in a post-polymerization step to exhibit hydroxyl groups. Such monomers include, for example, vinyl ethers or esters, e.g., H2C=CH - O-(C=O) m R may be selected from the group of R where R is an alkyl group and m=0 or 1, and after polymerization such groups are hydrolyzed to give the residue -CH-CH(OH)- in the polymer chain.

[0101] Increasing the proportion of fluorine-containing monomer in the fluoropolymer improves the weather resistance of the coated film, while decreasing it improves the solubility of the fluoropolymer. The proportion of fluorine-containing monomer to the total monomer amount is preferably between 30 and 70 mol %, more preferably between 40 and 60 mol %.

[0102] The hydroxyl group content of the fluoropolymer is preferably 30 to 200 mgKOH / g, more preferably 40 to 150 mgKOH / g.

[0103] Preferably, the fluorine content of the fluoropolymer is in the range of 5% to 35% by weight, more preferably 10% to 35% by weight, based on the weight of the polymer.

[0104] Radically polymerized hydroxyl-functional fluoropolymers are commercially available, for example, from Daikin Industries as Zeffle® GK polymers and from Asahi Glass Co. as LUMIFLON® polymers.

[0105] In place of or in combination with the aforementioned radically polymerized hydroxyl-functional fluoropolymers, hydroxy-functional poly(meth)acrylates can be used to form the clear thermoset polyurethane coating layer (D).

[0106] Such hydroxy-functional poly(meth)acrylates preferably include, in addition to hydroxy-functional (meth)acrylates, hydroxyalkyl (meth)acrylates such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and hydroxybutyl (meth)acrylate, alkyl (meth)acrylates (wherein the alkyl group preferably has 1 to 8 carbon atoms), styrene, and (meth)acrylic acid and their acid-functional derivatives. Preferred monomers of the latter type contained in the hydroxy-functional poly(meth)acrylate include, but are not limited to, (meth)acrylic acid, 2-alkyl(meth)acrylic acids (wherein the alkyl has 2 to 8, preferably 2 to 6, carbon atoms, such as 2-ethyl(meth)acrylic acid, 2-propyl(meth)acrylic acid, 2-butyl(meth)acrylic acid, and 2-hexamethyl(meth)acrylic acid), halogenated alkyl(meth)acrylic acids, such as 2-(trifluoromethyl)(meth)acrylic acid, and halogenated (meth)acrylic acids, such as 2-bromo(meth)acrylic acid, and salts of the foregoing acids, preferably alkali metal salts, such as sodium, potassium, or zinc salts.

[0107] Preferably, the hydroxy-functional poly(meth)acrylate has a hydroxyl number of 50 to 200 mg KOH / g, more preferably 60 to 160 mg KOH / g, even more preferably 70 to 150 mg KOH / g.

[0108] Preferably, the hydroxy-functional poly(meth)acrylate has a number average molecular weight, determined by gas permeation chromatography using a styrene standard, of 5,000 to 50,000 g / mol, more preferably 10,000 to 40,000 g / mol, and even more preferably 12,000 to 30,000 g / mol.

[0109] The radically polymerized hydroxyl-functional fluoropolymer and hydroxyl-functional poly(meth)acrylate can be used alone or blended with each other. The preferred blend ratio can range from 90:10% to 10:90% by weight, and most preferably 70:30% and 30:70% by weight, depending on the required performance.

[0110] In particular, with regard to adhesion on a transparent radiation-cured (meth)acrylate layer (C), it has surprisingly been found that the use of a radically polymerized hydroxyl-functional fluoropolymer is preferred when used alone or in combination with a hydroxy-functional poly(meth)acrylate, and most preferred when used alone.

[0111] Polyisocyanate To form a transparent thermoset coating layer (D), preferably a transparent thermoset polyurethane coating layer (D), the aforementioned hydroxyl-functional polymers must be crosslinked, preferably by a crosslinking agent such as a polyisocyanate.

[0112] In the context of the present invention, the term "polyisocyanate" means a compound containing at least two free, i.e., unblocked, isocyanate groups. The term polyisocyanate thus includes, for example, diisocyanates and triisocyanates, but also oligomers of such diisocyanates and triisocyanates, for example, dimers and trimers of such diisocyanates and triisocyanates.

[0113] When the term "hydrophobic" is used in conjunction with the term "polyisocyanate," this term indicates that the polyisocyanate typically does not contain hydrophilic groups, especially charged groups or polyethylene oxide groups, but rather contains only hydrocarbyl groups other than the isocyanate groups themselves and groups obtained by oligomerization of isocyanate groups.

[0114] The most preferred polyisocyanates are hydrophobic polyisocyanates.

[0115] The polyisocyanates used to form the transparent thermoset polyurethane coating layer (D) are selected from the group consisting of aliphatic, araliphatic, and aromatic polyisocyanates, including cycloaliphatic polyisocyanates. Oligomers of diisocyanates and triisocyanates are formed from the same diisocyanate or triisocyanate, but also from mixtures thereof.

[0116] Examples of aliphatic diisocyanates are, for example, 1,4-tetramethylene diisocyanate, ethyl (2,6-diisocyanato) hexanoate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, and examples of aliphatic triisocyanates are, for example, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanato-4-isocyanatomethyloctane, or 2-isocyanatoethyl (2,6-diisocyanato) hexanoate. Examples of alicyclic diisocyanates are, for example, 1,4-tetramethylene diisocyanate, ethyl (2,6-diisocyanato) hexanoate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, and examples of aliphatic triisocyanates are, for example, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanato-4-isocyanatomethyloctane, or 2-isocyanatoethyl (2,6-diisocyanato) hexanoate. Cyanates are, for example, 1,3- or 1,4-bis(isocyanatomethylcyclohexane), dicyclomethane-4,4′-diisocyanate, 1,3- or 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl(3-isocyanato-3-methyl)cyclohexylisocyanate, dicyclohexylmethane-4,4′-diisocyanate, or 2,5- or 2,6-diisocyanatomethylnorbornane, and cycloaliphatic triisocyanates are, for example, 2,5- or 2,6-diisocyanatomethyl-2-isocyanatopropylnorbornane.

[0117] Examples of araliphatic polyisocyanates are, for example, aralkylene diisocyanates, such as m-xylylene diisocyanate or a,a,a',a'-tetramethyl-m-xylylene diisocyanate.

[0118] Examples of aromatic diisocyanates are, for example, m- or p-phenylene diisocyanate, tolylene-2,4- or 2,6-diisocyanate, diphenylmethane-4,4′-diisocyanate, naphthalene-1,5-diisocyanate, diphenyl-4,4′-diisocyanate, 4,4′-diisocyanato-3,3′-dimethyldiphenyl, 3-methyl-diphenylmethane-4,4′-diisocyanate, or diphenylether-4,4′-diisocyanate, and examples of aromatic triisocyanates are, for example, triphenylmethane triisocyanate or tris(isocyanatophenyl)-thiophosphate.

[0119] Examples of oligomeric polyisocyanates include diisocyanates or polyisocyanates having a uretdione structure obtained by cyclodimerization of the isocyanate groups of the above-mentioned various diisocyanates and triisocyanates, polyisocyanates having an isocyanurate structure or an iminooxadiazinedione structure obtained by cyclotrimerization of the isocyanate groups of the above-mentioned various diisocyanates and triisocyanates, polyisocyanates having a biuret structure obtained by reacting the above-mentioned various diisocyanates or triisocyanates with water, polyisocyanates having an oxadiazinetrione structure obtained by reacting the above-mentioned various diisocyanates or triisocyanates with carbon dioxide, and polyisocyanates having an allophanate structure.

[0120] Preferred polyisocyanates are aliphatic or alicyclic di- or triisocyanates, aralkylene diisocyanates, or oligomers derived therefrom, in view of the stability of the isocyanate groups in water and the weather resistance of cured layers containing such polyisocyanates.

[0121] Highly preferred polyisocyanates are those having a functionality of three or more, such as isocyanurate or iminooxadiazinedione polyisocyanates, polyisocyanates having a biuret structure, polyisocyanates having a uretdione structure, polyisocyanates having an allophanate structure, or polyisocyanates obtained by reacting a diisocyanate with a polyhydric alcohol having a functionality of three or more. The core of the polyisocyanate preferably contains an aliphatic polyisocyanate or a trimer derived therefrom.

[0122] Aromatic polyisocyanates have been observed to result in increased yellowing of the layer upon storage under temperature and humidity conditions or after extensive exposure to UV radiation, therefore aliphatic polyisocyanates are preferred in the present invention.

[0123] Particularly preferred polyisocyanate compounds include hexamethylene diisocyanate (HDI), isocyanurate trimers or iminooxadiazinedione trimers derived therefrom, isophorone diisocyanate (IPDI) and IPDI-based isocyanurates or iminooxadiazinediones, and dicyclohexylmethane diisocyanate (H12MDI) and H12MDI-based isocyanurates or iminooxadiazinediones. Isocyanurates or iminooxadiazinediones of the above diisocyanates are preferred.

[0124] The transparent heat-cured coating layer (D) may further contain additives such as UV absorbers, light stabilizers, and antioxidants, which can be the same as those described for the transparent radiation-cured (meth)acrylate layer (C) to improve weathering performance and lifespan by enhancing UV and thermal stability. The UV absorbers, light stabilizers, and antioxidants are preferably present in the same amount ranges as described above for the transparent radiation-cured (meth)acrylate layer (C).

[0125] The transparent thermoset coating layer (D) is characterized by a glass transition temperature that is preferably higher than 10°C, more preferably higher than 50°C, but preferably lower than 100°C.

[0126] The final thickness of the transparent thermosetting coating layer (D) is preferably in the range of 10 μm to 100 μm, more preferably in the range of 20 μm to 80 μm, and most preferably in the range of 25 μm to 60 μm.

[0127] Specific Embodiments of MLBF and MLBF-Coated Substrates In one embodiment, the MLBF architecture on the substrate is as follows: [Base material (A)]-(B)-(C)-(D) In this embodiment, layer (B) i ) or layer (B i B o ) n (B i ) t and all definitions are as above. Figure 1 shows this embodiment when the optional planarization layer (P) in Figure 1 is omitted. Figure 2 shows a possible microconfiguration of (B), i.e., (B i B o ) n (B i ) t where n=2 and t=1 and 0 in FIG. 2, respectively.

[0128] In a further embodiment, the MLBF configuration on the substrate is as follows: [Base material (A)]-(P)-(B)-(C)-(D) In this embodiment, layer (B) i ) or layer (B i B o ) n (B i ) twhere all definitions are as above, and layer (P) can be the same as layer (C), where all definitions are as above, and both layers (C) can be the same or different. Figure 1 shows this embodiment when the optional planarization layer (P) of Figure 1 is present. Figure 2 shows possible microconfigurations of (B), i.e., (B i B o ) n (B i ) t In Fig. 2, n=2 and t=1, 0, respectively.

[0129] In yet another embodiment, the MLBF configuration on the substrate is as follows: [Base material (A)]-[(B)-(C)] a -(D) In this embodiment, layer (B) i ) or layer (B i B o ) n (B i ) t where all definitions are as above, and the sequence [(B)-(C)] can be repeated a times, where a is an integer between 1 and 10. When a≧2, the a layers (B) can be the same or different, and the a layers (C) can be the same or different. This embodiment is shown in FIG. 3 with a=2, and when b is 0 in FIG. 3, FIG. 2 still shows the possible microconfigurations of (B), i.e., (B i B o ) n (B i ) t In Fig. 2, n=2 and t=1, 0, respectively.

[0130] In a typical embodiment, the MLBF configuration on the substrate is as follows: [Base material (A)]-(P) b -[(B)-(C)] a -(D) In this embodiment, layer (B) is layer (B i ) or layer (B i B o )n (B) i t where all definitions are as above, and the layer sequence [(B)-(C)] can be repeated a times, where a is an integer from 1 to 10. If a≧2, the a layers (B) can be the same or different, and the a layers (C) can be the same or different, and b=0 or 1. Thus, the planarization layer can be present (b=1) or absent (b=0). This embodiment is shown in FIG. 3 with a=2 and p=1. In this general embodiment, as well as in all specific embodiments shown herein, at least one layer (C) is in direct contact with one layer (D).

[0131] Common to all of the aforementioned MLBF configurations is that the sequence of layers starting from [substrate (A)] is (B)-(C)-(D) regardless of the fact that it is preceded by a planarization layer (P) between the substrate and the first layer (B), or the sequence can be interrupted by a further sequence such as one or more additional sequences [(B)-(C)] after the first sequence [(B)-(C)], or the sequence can be interrupted by a further layer between layers (B) and (C) and / or layers (C) and (D).

[0132] Preferably, layer (D) is directly on top of layer (C), which is directly on top of layer (B), so that all three essential layers of the MLBF are in direct contact, i.e., there are no layers between the three essential layers.

[0133] The aforementioned configurations are selected depending on the application requirements, the desired level of moisture barrier (WVTR), and the desired type of polymer film substrate. For example, repeating layers (B) and (C) typically provides an improved moisture barrier due to the presence of multiple layers (B), but a polymer film as a substrate may require a planarizing layer (P) if the substrate has surface irregularities. If a more flexible MLBF is required in the application, layer (B) may be used in place of (B). i B o ) n (B) i tIt may have the following structure.

[0134] For all of the foregoing embodiments, the substrate is preferably a polymeric substrate, and even more preferably a transparent polymeric substrate.

[0135] Features of the MLBF of the present invention The MLBF of the present invention typically has excellent long-term thermal stability of at least 2000 hours at 85°C and 85% relative humidity without self-peeling or crack formation. In particular, when aliphatic monomers and oligomers are used to prepare the transparent radiation-cured (meth)acrylate layer (C) and the transparent thermally cured coating layer (D), the increase in yellowness index (YI) after extensive climatic aging is typically less than 10.

[0136] The MLBF of the present invention exhibits good UV stability with an outdoor life of more than 20 years, as estimated by less than 5% variation in transmittance in the wavelength range of light from 400 to 1100 nm in UV accelerated metal halide irradiation tests for at least 400 hours, and even up to more than 800 hours.

[0137] Method for producing a multilayer barrier film and a substrate coated in this way The present invention provides a method for producing a method for manufacturing a semiconductor device, comprising at least the following steps: a. providing a substrate; b. applying one or more inorganic layers onto the substrate by one or more methods selected from chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) and sputtering to form one or more transparent, at least partially inorganic barrier layers (B); and c. applying one or more radiation-curable (meth)acrylic coating compositions C onto one or more transparent, at least partially inorganic barrier layers (B) to form one or more transparent, radiation-curable (meth)acrylate layers and curing the layer(s) to form one or more radiation-cured (meth)acrylate layers (C); and d. applying one or more thermosetting coating compositions D onto the one or more radiation-cured (meth)acrylate layers (C) to form one or more thermosetting coating layers D, and curing the layer(s) to form one or more clear thermosetting coating layers (D); The present invention provides a method for producing a multilayer barrier film, comprising:

[0138] Process a. The substrate used in the above method can be any of the substrates described above, but is most preferably a polymeric substrate, and even more preferably a transparent polymeric substrate selected from those described above.

[0139] Substrates, particularly polymeric substrates, may typically be surface treated to enhance adhesion between the support and the layer provided thereon. Examples of such surface treatments include, but are not limited to, corona discharge treatment, flame treatment, UV treatment, low-pressure plasma treatment, and atmospheric pressure plasma treatment.

[0140] The substrate may be a pre-coated substrate, comprising, for example, a planarizing layer (P) which may be of the same type as the radiation-cured (meth)acrylic layer (C) described above and described above.

[0141] When the substrate is provided with such a planarizing layer (P), the coating composition is preferably of the same type as the above-mentioned radiation-curable coating composition C. Such a coating layer is therefore applied and cured in the same manner as described below for radiation-curable coating composition C. The thickness of the cured planarizing layer (P), if present, is preferably in the range of 0.5 to 10 μm, more preferably in the range of 1 to 5 μm.

[0142] Process b. The inorganic layer(s) are applied to the substrate by one or more methods selected from chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) and sputtering to form one or more transparent, at least partially inorganic barrier layers (B).

[0143] The aforementioned methods are known to those skilled in the art. CVD methods for producing such layers are described, for example, in DE 4035951 C1 or CA 2562914 A1 and references therein, PVD methods for producing such layers are described, for example, in EP 0645470 A1 or US 5900271 A and references therein, and sputtering methods for producing such layers are described, for example, in US 2004 / 0005482 A1. Furthermore, reference is made to the above paragraphs describing inorganic materials, i.e., metal oxides, metal nitrides and metal oxynitrides, and to the literature describing suitable application methods.

[0144] However, the transparent barrier layer or layers, when such layers are only inorganic, preferably metal oxide layers, are most preferably produced using ALD methods, which are described in detail, for example, in WO 2011 / 099858 A1.

[0145] When one or more inorganic layers are applied, it is also possible to apply an organic layer containing organic molecules between two or more inorganic layers (e.g. applied by ALD), e.g. by molecular layer deposition techniques.

[0146] Such a layer (B o The organic molecules used in the MLD technique to obtain the inorganic layer (B) are thiols, disulfides, sulfides, selenols, amines, carboxylates, phosphates or phosphonates, or their derivatives. i ), preferably a metal oxide layer (B i ) has a special functional group that can chemically bond to it.

[0147] Layer (B o The most preferred organic molecules for generating ) belong to the family of aromatic thiols, such as mercaptobenzoic acid, mercaptophenol, aminomercaptophenol, etc.

[0148] The application of such layers by MLD is described, for example, in WO2015 / 030297A1, WO2015 / 188990A2 and WO2015 / 188992A1, which are incorporated herein by reference.

[0149] Process c. In step c., a radiation-curable (meth)acrylic coating composition C is applied. This coating composition C comprises the following components: i. one or more radiation-curable oligomeric (meth)acrylate functional species; ii. one or more radiation-curable (meth)acrylate-functional monomers; iii. one or more adhesion promoters; iv. For UV curing, one or more photoinitiators; v. one or more compounds selected from UV absorbers, light stabilizers, and antioxidants, and vi. optionally one or more coating additives It comprises or consists of:

[0150] These material components, as well as their preferred contents in Coating Composition C, are described in detail above.

[0151] Since the radiation-curable coating composition C must be radiation-curable to form the transparent radiation-cured (meth)acrylic layer(s) (C), this composition should preferably be substantially free of light-absorbing pigments and fillers.

[0152] Coating composition C may be applied by any suitable wet coating method. Suitable coating methods include, for example, spin coating, blade coating, knife coating, kiss roll coating, cast coating, slot orifice coating, calendar coating, die coating, dipping, brushing, bar casting, roller coating, flow coating, wire coating, spray coating, dip coating, Wheeler coating, cascade coating, curtain coating, air knife coating, gap coating, rotary screen, reverse roll coating, (reverse) gravure coating, metering rod (Meyer bar) coating, slot die (extrusion) coating, hot melt coating, roller coating, and flexographic coating. Suitable printing methods include silk screen printing, relief printing such as flexographic printing, inkjet printing, intaglio printing such as direct gravure printing or offset gravure printing, lithographic printing such as offset printing, or stencil printing such as screen printing.

[0153] For preferred UV curing, the curing wavelength range, intensity, and energy of the UV light are selected depending on the photosensitivity of the coating composition C. Typically, the wavelengths are in the UV-A, UV-B, and / or UV-C ranges. Preferably, the radiation comprises light with a wavelength of less than 400 nm, more preferably light with a wavelength of less than 380 nm. Particularly preferred is radiation with a UV-Vis intensity of at least 600 mJ / cm. 2 , and better still 800 mJ / cm 2 The use of a UV mercury lamp as the radiation source.

[0154] To enhance the barrier function of the MLBF, steps b. and c. can be repeated one or more times.

[0155] Process d. In step d., a thermosetting coating composition D is applied onto the one or more radiation-cured (meth)acrylate layers (C) to form one or more thermosetting coating layers D, and the layer(s) are cured to form one or more transparent thermosetting coating layers (D).

[0156] The coating composition D comprises the following components: i. one or more hydroxyl-functional polymers selected from hydroxyl-functional fluoropolymers and hydroxyl-functional poly(meth)acrylates; ii. one or more polyisocyanates; iii. one or more organic solvents; iv. one or more compounds selected from UV absorbers, light stabilizers, and antioxidants; v. optionally, one or more catalysts for catalyzing the reaction between i. and ii.; and vi. optionally one or more coating additives It comprises or consists of:

[0157] The material components i. and ii. have been described in detail above. The UV absorbers, light stabilizers and antioxidants iv. can be selected from the same groups as those disclosed for the radiation-curable coating composition C.

[0158] Typically, the coating composition D comprises a solvent iii. selected from the group of aprotic solvents, such as esters, for example butyl acetate and ethyl acetate, ketones, for example methyl ethyl ketone, alkyl ethers, for example methoxypropanol or glycol ethers, aliphatic or aromatic hydrocarbons, for example hexane, heptane, cyclohexane, benzene, toluene and xylene.

[0159] The catalyst v. that may be used to catalyze the crosslinking reaction between the hydroxyl-functional polymer(s) i. and the polyisocyanate(s) ii. is preferably selected from the group of tin-based catalysts, such as dibutyltin dilaurate (DBTL) or dioctyltin laurate. However, it is advantageous to use zinc- or bismuth-based catalysts instead of the commonly used tin-based catalysts. Examples of zinc-based catalysts include K-KAT-XK-622 and XK-614 from King Industries and Octa-Soligen® Zn catalyst from Borchers. Examples of bismuth-based catalysts include Borchi® Kat 0243, Borchi® Kat 0244, and Borchi® Kat 315 from Borchers.

[0160] Coating composition D may further comprise typical coating additives such as those described for radiation-curable coating composition C, which are not radiation-curable in contrast to those preferably used in radiation-curable coating composition C.

[0161] To avoid premature crosslinking, at least material components i. and ii. are stored separately. Other material components may be contained in i. or ii. under storage conditions, in particular solvents may be contained in i. and / or ii. When stored in a premix with i., care should be taken to ensure that the material component is not reactive with i., and the same applies to material components stored in a premix with ii.

[0162] The above material components i. to vi. are not meant to be exclusive to the presence of other material components reactive with material component ii., such as reactive diluents, reactive oligomers and polymers, or crosslinkers other than ii. However, it is preferred that coating composition D consists of material components i. to vi.

[0163] Because the thermosetting coating composition D must be thermosetting to form the transparent thermosetting layer(s) (D), the composition should preferably be substantially free of light-absorbing pigments and fillers.

[0164] The preferred amounts of the material components i. to vi. used in the coating composition D are as follows: i. preferably in the range of 10 to 60% by mass, most preferably 20 to 50% by mass; ii. preferably in the range of 5 to 20% by weight, most preferably in the range of 7 to 15% by weight; iii. preferably in the range of 20 to 70% by mass, most preferably in the range of 30 to 70% by mass, iv. preferably in the range of 0.1 to 10% by mass, most preferably in the range of 0.2 to 5.0% by mass; v. preferably in the range of 0 to 0.1 mass%, most preferably in the range of 0.02 to 0.07 mass%, vi. Preferably in the range of 0 to 5% by mass, most preferably in the range of 1 to 4% by mass. All weight percent values are based on the total weight of Coating Composition D.

[0165] Coating Composition D can be applied by any suitable wet coating method, as previously described for Coating Composition C above.

[0166] The layer thus obtained can be cured at a temperature preferably in the range of ambient temperature (25°C) to 100°C, preferably in the range of 50°C to 90°C, and even more preferably in the range of 65 to 85°C, for a time preferably in the range of 1 to 120 minutes, more preferably in the range of 1 to 60 minutes, and even more preferably in the range of 1 to 30 minutes, 1 to 15 minutes, or 2 to 10 minutes. Generally, the higher the curing temperature, the shorter the curing time.

[0167] Methods of using multilayer barrier films and MLBF coated substrates Such MLBF-coated substrate can be used as a protective sheet for photovoltaic applications.Due to its light weight, flexibility and advantageous cost, such protective sheet can be preferably used as a front protective sheet (front sheet) or a back protective sheet (back sheet) in applications such as solar cell modules, and other possible applications include portable lighting devices, advanced packaging for optoelectronics, and displays such as OLED screens. [Example]

[0168] The present invention will now be illustrated by the following examples, in which all parts are by weight and percentage values relating to material components of compositions are by weight unless otherwise specified.

[0169] Test Procedure Testing of Outer Curable / Cured Coating Composition D Coating Composition D was stored in a sealed amber glass bottle at a temperature of 23±2° C. in unhumidified air for at least 24 hours.

[0170] viscosity Viscosity was measured using a torque rotational viscometer Brookfield CAP2000+ at 100 rpm and 25°C 1 hour after mixing.

[0171] Glass transition temperature (DSC) DSC was performed using a Mettler Toledo Star System TGA / DSC1 instrument at a heating rate of 10°C / min during the first heating cycle.

[0172] Thermogravimetric analysis (TGA) TGA was performed using a Mettler Toledo Star System TGA / DSC1 instrument at a heating rate of 10°C / min under a N2 atmosphere.

[0173] Dynamic mechanical analysis (DMA) DMA was performed using a Waters TA Instrument Discovery DMA850. Measurements were carried out at 20°C. (a) Storage modulus (b) Tensile strength (c) E-modulus (d) Breaking elongation

[0174] Multilayer system testing All tests performed on the MLBF were performed after a 24 hour conditioning period at 23±2° C. and 50% relative humidity, except for the UV stability data, where no temperature and humidity control was performed during sample conditioning.

[0175] Heat stability / humid heat test The thermal stability of the MLBF coated substrates was tested by storing the MLBF coated substrates at 85°C and 85% relative humidity for 2000 hours.

[0176] Cross-cut adhesion Cross-cut adhesion of the tape was measured according to ASTM D3359-17 (6 blades spaced 2 mm apart).

[0177] Haze, transparency and transmittance Haze, clarity, and transmittance were measured according to ASTM1003D:2013.

[0178] yellow index The yellowing index was determined according to DIN 6167:1980-01.

[0179] UV stability 1.5kW / m 2 UV radiation in the wavelength range of 295-400 nm was irradiated onto the MLBF for 820 hours at a temperature of 70°C and a relative humidity of 40% using a Super UV-W161 metal halide device.

[0180] Coating layer thickness Layer thicknesses were measured for the dried or cured layers (P), (B), (C) and (D) by non-destructive dry film measurement using a coating thickness gauge such as a Byko-Test 4200 (available from BYK Instruments).

[0181] Multilayer systems and their preparation List of material ingredients

[0182] [Table 1]

[0183] Transparent polymer substrate (A) As a transparent polymer substrate, a clear, high-gloss, heat-stabilized polyester film (polyethylene terephthalate; PET) having a film thickness of 125 μm and available from DuPont Tijin Films under the trademark MELINEX® ST504 was used.

[0184] a transparent, at least partially inorganic barrier layer (B) A transparent, at least partially inorganic barrier layer (B) was applied onto the transparent polymer substrate by atomic layer deposition (ALD) of aluminium oxide with a layer thickness of 100 nm, as described for example in WO2015 / 188990A2 and WO2015 / 188992A1.

[0185] Transparent radiation-cured (meth)acrylate layer (C) Two different radiation-curable (meth)acrylate compositions C1 and C2 were used to prepare transparent radiation-cured (meth)acrylate layers (C). Each of the compositions C1 and C2 was applied onto the transparent inorganic barrier layer (B) with an automatic bar coater metal blade (ZEHNTNER ZAA2300) at a speed of about 20 mm / s and then irradiated with UV mercury lamp (UVA2: 220 mJ / cm). 2 , UV-Vis: 580 mJ / cm 2, speed: 5.6 m / min, gap: 6 cm) to produce a transparent radiation-cured (meth)acrylate layer (C) with a dry layer thickness of about 22.5±2.5 μm.

[0186] The material components of compositions C1 and C2 used are summarized in Table 1 below, the amounts being parts by weight in the commercially available form.

[0187] [Table 2]

[0188] Clear thermoset outer coating layer (D) Eight different thermosetting coating compositions (D1 to D8) were used to prepare the transparent, thermosetting outer coating layer (D) of multilayer system Examples 1 to 9. The compositions were applied onto the radiation-cured (meth)acrylate layer (C) using a bar coater metal blade (20 mm / min) and cured at 80°C for 2 minutes (compositions D1 to D6) and 3 minutes (compositions D7 and D8), respectively, to produce a transparent, thermosetting outer coating layer (D) with a dry layer thickness of 47.5±2.5 μm.

[0189] To prepare thermosetting coating compositions D1-D8, the crosslinkable polymer shown in Table 2 was mixed with the solvent components, followed by the addition of the crosslinker to produce a homogeneous mixture. The catalyst, UV absorber, and light stabilizer were then added. Compositions D3 and D6 were further diluted with butyl acetate in an amount of 6 g prior to application.

[0190] [Table 3]

[0191] Table 3 shows the multilayer structures and properties of Examples 1 to 9.

[0192] [Table 4]

[0193] The results in Table 3 clearly demonstrate that there was no visible self-peeling for any of the MLBF-coated substrates of the present invention after 2000 hours of thermal stability testing. Furthermore, under the rather rigorous cross-cut adhesion test conditions, the samples (Examples 1-4) using only fluoropolymer in layer (D) exhibited excellent adhesion in this test, due to 100% film integrity. The same was true for samples using only hydroxyl-functional poly(meth)acrylate in layer (D). Preliminary results (not shown) indicate that the fluoropolymer-containing layer (D) exhibited better cross-cut adhesion after storage under high temperature and humidity.

[0194] All other results showed little or no change in haze, clarity, transmittance, yellowness index and UV stability even under 2000 hours of damp heat test conditions, indicating excellent long-term stability of MLBF coated substrates.

Claims

1. A multilayer barrier film for coating a transparent polymer substrate (A), comprising the following in this order: (B), (C), and (D): one or more transparent, at least partially inorganic barrier layers (B), one or more transparent, radiation-cured (meth)acrylate layers (C), and One or more transparent, thermoset coating layers (D) wherein at least one layer (C) is in direct contact with one layer (D).

2. the thickness of said one or more barrier layers (B) is in the range of 10 nm to 1000 nm, and / or the thickness of said one or more radiation-cured (meth)acrylate layers (C) is in the range of 1 μm to 100 μm, and / or 2. The multilayer barrier film of claim 1, wherein the thickness of the one or more thermosetting coating layers (D) is in the range of 10 to 100 μm.

3. 3. The multilayer barrier film according to claim 1 or 2, characterized in that a planarization layer (P) for planarizing the transparent polymer substrate (A) is provided on the barrier layer (B) on the side opposite to the one or more radiation-cured (meth)acrylate layers (C).

4. 4. The multilayer barrier film according to claim 3, wherein the thickness of the planarization layer (P) is in the range of 1 to 30 μm.

5. The barrier layer (B) is an inorganic layer (B) formed by atomic layer deposition and made of one or more inorganic materials selected from the group consisting of metal oxides, metal nitrides, metal oxynitrides, and combinations thereof. ｉ 3. The multilayer barrier film according to claim 1 or 2, wherein

6. The barrier layer (B) is a layer stack (B ｉ B ｏ ) ｎ (B ｉ ) ｔ It consists of B ｉ is the inorganic layer, and B ｏ is an organic layer formed by molecular layer deposition, n=1 to 100, and t=0 or 1, and n B ｉ 3. A multilayer barrier film according to claim 1 or 2, characterized in that the first of the layers is formed on a planarizing layer (P) or on a substrate (A).

7. 3. A multilayer barrier film according to claim 1 or 2, characterized in that the one or more radiation-cured (meth)acrylate layers (C) are obtained by radiation curing a radiation-curable coating composition C comprising at least one or more radiation-curable oligomeric (meth)acrylate-functional species and at least one or more radiation-curable (meth)acrylate-functional monomers.

8. The stack of layers (B) and (C) is [(B)-(C)] ａ The multilayer barrier film according to claim 1 or 2, characterized in that it is present a times in the form of

9. The one or more thermoset coating layers (D) comprise the following components: at least one hydroxyl-functional polymer selected from radically polymerized hydroxyl-functional fluoropolymers and hydroxyl-functional poly(meth)acrylates; and At least a crosslinking agent selected from the group of polyisocyanates 3. A multilayer barrier film according to claim 1 or 2, characterized in that it is a polyurethane layer obtained by applying a coating composition D comprising

10. 3. The multilayer barrier film according to claim 1, wherein layer (C) and / or layer (D) comprises at least one additive from the group consisting of UV absorbers, light stabilizers and antioxidants.

11. 3. A multilayer barrier film-coated substrate comprising the multilayer barrier film defined in claim 1 or 2, characterized in that the multilayer barrier film coats the transparent polymer substrate (A) in the order [substrate (A)]-(B)-(C)-(D).

12. 12. The multilayer barrier film coated substrate of claim 11, characterized in that it has a thickness in the range of 20 μm to 300 μm.

13. 12. The multilayer barrier film coated substrate of claim 11, wherein the substrate is a transparent polyethylene terephthalate substrate.

14. 3. A method for producing a multilayer barrier film as defined in claim 1 or 2, comprising the steps of: a. providing a substrate and forming the multilayer barrier film onto the substrate by: b. applying one or more inorganic layers onto the substrate by one or more methods selected from chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) and sputtering to form one or more transparent, at least partially inorganic barrier layers (B); and c. applying one or more radiation-curable (meth)acrylic coating compositions C onto the one or more transparent, at least partially inorganic barrier layers (B) to form one or more transparent, radiation-curable (meth)acrylate layers and curing the layer(s) to form one or more radiation-cured (meth)acrylate layers (C); and d. applying one or more thermosetting coating compositions D onto the one or more radiation-cured (meth)acrylate layers (C) to form one or more thermosetting coating layers D, and curing the layer(s) to form one or more clear thermosetting coating layers (D). Including, A method for producing a multilayer barrier film, which does not exclude additional steps between steps a. and b., steps b. and c., and steps c. and d.

15. 15. A method for producing a multilayer barrier film-coated substrate as defined in claim 11 by carrying out steps a. to d. as defined in claim 14 using a transparent polymer substrate (A) as the substrate.

16. 12. Use of a multilayer barrier film coated substrate as defined in claim 11 in photovoltaic applications.

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