Edge seal for manufacturing two-pane or multi-pane insulating glass or solar modules comprising a photocured acrylic sealant composition as secondary sealant

Abstract

The invention provides an edge seal for manufacturing two-pane or multi-pane insulating glass or solar modules, comprising at least one photocured acrylic sealant composition as a secondary sealant. It also provides a photocurable acrylic sealant composition. The edge seal may be used for manufacturing insulating glass for windows, conservatories, structural glazing and roof glazing; for glazing in landbound vehicles, watercraft and aircraft, or for fabricating solar modules. Also provided is a method for preparing the edge seal and an assembly line.

Description

[0001] Title: Edge seal for manufacturing two-pane or multi-pane insulating glass or solar modules comprising a photocured acrylic sealant composition as secondary sealant

[0002] Technical Field

[0003] The present invention relates to an edge seal for manufacturing two-pane or multi-pane insulating glass or solar modules. More in particular, it relates to a photocurable acrylic sealant composition as secondary sealant that can be cured completely in depth (at least 10 mm) within 1 hour, preferably within 10 minutes, for use in such a two-pane or multi-pane insulating glass units or solar modules.

[0004] Background Art

[0005] Insulating glass units (IG units) consist of two or more glass panes separated from each other by a spacer (spacer bar or spacer frame), wherein the arrangement may be sealed by a sealant composition, typically with a combination of two different sealant compositions (a so- called primary sealing material and a so-called secondary sealing material). The insulating glass units can preferably be filled with various gases (e.g. noble gases such as argon, krypton or xenon, or heavy gases such as sulphur hexafluoride) to improve the heat and sound insulation. The primary sealing material serves to seal the unit against penetrating atmospheric humidity and against emergent filling gases and is usually based on isobutylene polymers which have only low cohesive strength. The primary sealing material is arranged between the spacer and the glass. If a separate, secondary sealing material is used, then it ensures elasticity, adhesion, and cohesive strength, filling the joint formed between the glass panes and the spacer and providing mechanical stability to the unit. The secondary sealing material is typically in the form of sealant compositions based on polyurethane, polysulphide or silicone. These sealant compositions can be used as single-component sealant composition which cure by means of atmospheric humidity or atmospheric oxygen. More commonly, two-component sealant compositions that cure at room temperature are used in which one part contains the polymer component and the other part contains a crosslinker or hardener component. The secondary sealing material can additionally contain silanes for improved glass adhesion. The combination of spacer, and sealing material, e.g., primary sealing material, and secondary sealing material, is usually referred to as a so-called edge seal.

[0006] Background information may be found in an article by S. Van den Bergh et al., “Window Spacers and Edge Seals in Insulating Glass Units: A State-of-the-Art Review and Future Perspectives”, published in Energy and Buildings 58 (2013) 263-280, which is included herein by reference.

[0007] For instance, US2022195263 relates to a system for producing a sealant composition composite made of a primary sealing material and a curable secondary sealing material, the use of the system for producing insulating glass or solar modules, an edge seal for producing double-pane or multi-pane insulating glass or solar modules comprising the sealant composition composite, and an insulating glass unit comprising at least two glass panes and the edge seal. In this system, the secondary sealing material is based on polyurethane or polysulphide. GB2454584 provides a two-part sealant composition, comprising a first part and a second part, wherein the first part comprises a polymer selected from silane-terminated polyurethane or silane-terminated polyether. In use, the first and second parts are mixed to achieve a cured substance having a 48 hour Shore A hardness in the range of 25-70. Also disclosed is use of the sealant composition in insulating glass units. EP3606996 provides insulating glass sealant compositions based on polyurethanes and organically-modified nanoclays. W02009036752 relates to a composite edge for producing double or multiple pane insulating glass or solar modules, wherein a special primary sealant composition and a silicone-based composition as secondary sealant composition are provided. EP0916801 describes and claims an insulating glass unit and a process for making such. The unit comprises two glass panes spaced apart by a spacer of thermoplastic material adherent to the panes, an inert or heavy gas trapped within the unit and a layer of silicone elastomer located at the periphery of the unit between the edge portions of the glass panes and in contact with the external surfaces of the spacer. The thermoplastic material has a water vapor permeability of not more than about 0.2 l / m2 / day (measured at 20 degrees Centigrade for 4 mm thickness) and a shear strength of more than 0.2 MPa as determined at a sealant composition thickness of 0.5 mm at 23 degrees Centigrade and a shear speed of 100 mm / min. The process described for making these units comprises providing between two glass panes an endless strip of the thermoplastic material in a plastic state applied as a hot melt containing a dehydrating material, urging the two glass panes towards each other against the thermoplastic material to form a spacer comprising the thermoplastic material adherent to the panes, introducing to the cavity defined by the two panes and the spacer an inert or heavy gas and applying a layer of silicone elastomer located at the periphery of the unit in contact with external surfaces of the spacer.

[0008] In addition, WO2015086457 discloses an insulating glazing for a building, comprising at least two panes, a circumferential polymer or metal spacer, appropriate sealant compositions between the panes and the spacers, and appropriate sealant compositions in the external intermediate space between the panes and an intermediate space filled with air or gas. The connection between two spacers on the corners of the insulating glazing unit is implemented by a corner connector, especially a plastic molded part, in which two miter-cut spacers are adjoined to each other. The inner chamber between the panes is filled with an inert gas before the assembly is pressed together.

[0009] From US2020408032, insulating glass units (1) are known, wherein the insulating glass unit includes at least one first and one second glass pane, at least one spacer consisting of glass, which is connected to each glass pane by at least one sealant composition, at least one other spacer which is gas-tight or comprises a gas-tight layer and is connected to each glass pane by at least one second sealant composition, and at least one joining region for a glass spacer and another spacer. The at least one glass spacer, the at least one other spacer and the glass panes form a closed inner chamber that does not affect the visual appearance. To this end, the at least one joining region is closed by a third sealant composition in a gas-tight manner, with the sealant composition containing polyisobutylene and being guided over the joining region. According to an advantageous embodiment of this insulating glass unit, the first sealant composition, by means of which the glass spacer is connected to the glass panes, or the second sealant composition, by means of which the additional spacer is connected to the glass panes, or both of the sealant compositions mentioned consist(s) of a primary sealant composition, which is disposed on the side facing the inner chamber, and a secondary sealant composition which is disposed on the side facing the external region. At least one of the primary and secondary sealant compositions mentioned is transparent. In addition, one of the primary sealant compositions or both primary sealant compositions may contain acrylic. According to an advantageous embodiment, one of the primary sealant compositions or both primary sealant compositions takes / take the form of a double-sided adhesive tape. One of the secondary sealant compositions or both secondary sealant compositions preferably contains / contain polyisobutylene.

[0010] A moisture-curable sealant containing also a radiation-curable meth(acrylic) functionality has been described in US2004181007A1. Such a dual-cure sealant composition requires two curing steps - a fast initial treatment with radiant energy providing the initial minimum mechanical performance (green strength) and slow moisture-curing phase resulting in the final strength. Such moisture-curing phase can take many days under poorly controlled conditions and thus the final product performance can be poorly reproducible. Furthermore, as may be known to those practicing the art of moisture-curable sealants, the presence of excessive moisture in contact with moisture-curable sealants can lead to uneven curing and bubble formation inside the sealant, which is unacceptable for the gas and moisture barrier function.

[0011] Production of laminated glass articles including photovoltaic modules and laminated glazing having a radiant- or heat cured acrylic edge seal has been revealed by WO2010 / 146389. In that embodiment, the thickness of the film is proportional to the amount of applied material and thicker films may be produced by repeated application, with typical thickness claimed to be less than 2 mm. This is not satisfactory for the production of insulating glass units according to EN1297 standard, where sealant thickness in the range of 5-10 mm is typically used, and the preferred sealant curing depth limit is at least 10 mm.

[0012] The demand for insulating glazing or insulating glass units is increasing with the need to preserve energy. A large body of art exists on the preparation of such units. Nonetheless, a need remains for alternative systems that can be used as sealing material. Such systems should be easy to apply, provide the required elastic adhesion, ability to fill the joint formed between the glass panes and the spacer and provide mechanical stability to the unit. A suitable sealant composition should be curable, without loss of solvents creating fogging inside the unit, and without interacting adversely with the isobutylene polymers or similar if used as primary sealant composition, and with long-lasting chemical stability. Moreover, the currently used secondary sealant compositions for insulating glass units take several hours to cure chemically (typical sealant composition types are polyurethanes, polysulphides, and silicones). During this time, glass units must be supported and not moved because structural integrity takes time to build. During this time, argon gas can leak out from the insulating glass units and product may be lost if deformation of seal occurs. It costs space, time, and labour productivity to wait for product curing. Also, there is interest in a one-component product that simplifies application on the insulating glass units compared to the currently used two- component polyurethanes, polysulphides, and silicones that require two-component mixing at a precise ratio, which may fail and produce defective product. Handling of two-component products requires more space, logistics, and labour.

[0013] Summary of the Invention

[0014] Accordingly, there is now provided an edge seal that overcomes the problems described above. The edge seal is defined in claim 1. Also claimed is the photocurable sealant composition, the method of preparing the edge seal and two-pane or multi-pane insulating glass or solar modules provided with the edge seal according to the present invention. The photocurable sealant composition may be a single component system (“1K”), a 2 component system (“2K”) or a multiple component system.

[0015] Drawing

[0016] Figure 1 is a schematic representation of a two-pane sealed insulating glass, wherein a spacer (5) containing a desiccant (4) is adhered to the glass panes (1) with an inner or primary sealant (3) and which is provided with an outer or secondary sealant (6). The secondary sealant (6) is applied to a height (r) on the back of the spacer and to a height (s) on the inner surface of the glass panes (1).

[0017] Detailed description of the Invention

[0018] As indicated in the review paper by Van Den Bergh et al mentioned above, IG units may be prepared with separate primary and secondary sealant compositions or with a single (secondary) sealant composition. Edge seals consist of a number of components, typically including a spacer, a desiccant, and the sealant composition.

[0019] In the edge seal according to the present invention a spacer, a desiccant and / or a primary sealant composition may be used. The current patent focusses on the secondary sealant composition which is applied around the perimeter of the glass. The secondary sealant composition functions as the adhesive that unites the glass panes and spacer and prevents excessive movement under different environmental stresses. Polyurethane (Pll), silicone (Si) and polysulphide (PS) are widely used as secondary sealant compositions, but hot-melt butyl- or epoxy-based sealant compositions may also be used. The present invention provides a further alternative. Although the photocurable acrylic sealant composition proposed in this application is referred to as secondary sealant composition, it is to be understood that it can also be used as single sealant composition, e.g., without a conventional primary sealant composition. The technology for applying sealant compositions onto glass panes is well known, as are the thickness and width of the sealant composition to provide a suitable seal. Throughout this application, the expression “spacer” is used to define spacer bars and frames, which may be pre-formed, but also spacers made of thermoplastic materials.

[0020] Photocurable acrylic compositions are well-known in applications as paints, varnishes, glues, and electronics potting. However, such photocurable compositions have not yet found large- scale use in the production of insulating glass units due to the limits of curing depth, adhesion, moisture and gas barrier performance, and the hazards of short-wave UV radiation to workers and equipment. The photocurable acrylic sealant compositions comprise one or more photocurable compounds carrying one or more acryl or methacryl functional groups per molecule (component a) and a photoinitiator (component b). In other words, the molecule may for instance have any polymeric backbone, provided it has one or more acryl or methacryl functional groups anywhere within the molecule.

[0021] It is also important to notice that the photocurable composition used in the present invention is isocyanate-free and does not rely on moisture cure. The photocurable compounds are cured, and moreover cured almost instantly to full depth, with the use of radiant energy that through the photoinitiator interacts with the acryl or methacryl functional groups. The photocurable compound carrying one or more acryl or methacryl functional groups may be a component with a molecular weight below 300 or with a molecular weight greater than 300, preferably greater than 1000. Examples of the former include butyl acrylate, (4-t- butylcyclohexyl)acrylate, and trimethylolpropane triacrylate. Examples of the latter include propoxylated neopentyl glycol diacrylate (PONPGDA), acrylated epoxidized soybean oil, and methacrylate-functionalized liquid polybutadiene such as Polyvest™ EP MAT from Evonik. Preferably, component (a) is selected from alkyl ester of acrylic or methacrylic acid, aliphatic urethane diacrylate, polyether polyacrylate, epoxidized fatty acid triglyceride polyacrylate, and acryl or methacryl-functionalized non-hydrogenated polydiene, each carrying one or more acryl or methacryl functional groups, or a mixture of such components.

[0022] Suitable alkyl ester of acrylic or methacrylic acid may be a C1-12 alkyl ester, preferably a C4-12 alkyl, more preferably selected from 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, lauryl acrylate, and 4-(t-butyl)cyclohexyl acrylate, commercially available as Laromer™ UA 9072 from BASF.

[0023] Suitable aliphatic urethane derivatives carrying one or more acryl or methacryl functional groups have a molecular weight greater than 1000. For instance, the following aliphatic urethane diacrylates may be used: Sartomer™ CN966H90, Sartomer CN965, Sartomer CN9002 from Arkema. A very suitable photocurable polyether polyacrylate is propoxylated neopentyl glycol diacrylate, commercially available as Sartomer SR9003.

[0024] Suitable fatty acid triglycerides carrying one or more acryl or methacryl functional groups have a molecular weight greater than 1000. A very suitable photocurable fatty acid triglyceride is acrylated epoxidized soybean oil.

[0025] Suitable non-hydrogenated polydienes carrying one or more acryl or methacryl functional groups have a molecular weight greater than 1000. For instance, a very suitable non- hydrogenated polydiene carrying methacryl functional groups is Polyvest™ EP MAT from Evonik.

[0026] The photocurable compound may also be a solution of prepolymers, oligomers or polymers in a solvent comprising acrylic monomers. For instance, it may be a polymerizable mixture containing monomers that include acrylic acid and / or acrylate ester (to be referred to as (meth)acrylate) that is partially polymerized. The partial polymerization is not limited to radiation-induced polymerization, and can also be carried out by thermal polymerization. Such a mixture may then be further UV cured. An example of a process for partial polymerization may be found in e.g., GB974473, GB923449, GB1021533, GB1057434, GB1425948, JPS56108707, US2003008140, US2003211250, EP1460118, EP2085444, JP2013166846, US2014120268, and KR20210102036. In addition to the one or more photocurable compounds carrying one or more acryl or methacryl functional groups per molecule (component a), also minor amounts, e.g., up to 5, suitably up to 2 mass % copolymerizable monomers, e.g., as reactive diluent, may be included. For example, up to 5% methacryl-functional silane (MEMO), or vinyl trimethoxysilane (VTMO) may be used.

[0027] In addition to the photocurable component (a), a photoinitiator (component b) is applied. The component (b) is selected from one or more photoinitiators that are suitable for inducing the polymerization of acrylates and / or methacrylates upon irradiation with visible or nearultraviolet light, where near-ultraviolet light is selected from wavelengths that do not create workplace hazard to exposed personnel. For instance, this photoinitiator may operate at 300- 480 nm wavelength, suitably 300-450 nm wavelength. Preferably, this is a photoinitiator that operates at 380-470 nm wavelength, suitably 380-410 nm wavelength. This may be a Norrish type I photoinitiator or a Norrish type II photoinitiator in combination with an appropriate amine synergist. Preferably, a photoinitiator is selected that readily dissolves in the photocurable compound or in the other components included in the photocurable composition. Examples of suitable photoinitiators available from the Arkema company include Speedcure™ 2100, Speedcure TPO, Speedcure BPO, Speedcure DETX in combination with ethyl 4- (dimethylamino)benzoate. A very suitable photoinitioator is diphenyl (2,4,6- trimethylbenzoyl)phosphine oxide, commercially available as Speedcure TPO. An alternative is a liquid blend of Norrish type I photoinitiators, available as Speedcure 2100. Suitable photoinitiators from Ciba include for instance Irgacure™ 819, Irgacure 651 , and Irgacure 184, which may be used even below 380 nm. Also combinations may be used.

[0028] The amount of photoinitiator depends on the particular photocurable compound. For instance, for a component (a) with a molecular weight below 200 a sufficient amount is in the range of 1-5% from the mass of component (a). For a component (a) with a higher molecular weight, a sufficient amount is in the range of 0.1-1%. Preferably, the amount of photoinitiator is in the range of 0.4-4.6% from the mass of component (a).

[0029] The curing may be completed with the use of additional radical initiators and / or with additional energy sources. In addition to the photoinitiators mentioned above, chain transfer agents and cross-linking agents may be used.

[0030] In addition, the photocurable composition may comprise one or more plasticizers as component (c). The plasticizer provides flexibility and lowers glass transition temperature that improves cold weather performance of edge seal. Preferably, the plasticizer has low volatility to avoid fogging inside insulating glass unit. Suitable plasticizers for photocurable acrylic sealant compositions include phthalates, terephthalates, benzoates, dibenzoates, and benzyl phthalates. A particularly suitable class of plasticizers are esters selected from one or more alkyl, aralkyl or mixed phthalate, alkyl or aralkyl terephthalate, alkyl or aralkyl benzoate or dibenzoate. Preferably a dialkyl phthalate is used, still more preferably dialkyl phthalate where the alkyl substituents each contain at least 9 carbon atoms, still more preferably diisononyl phthalate.

[0031] The amount of plasticizer, if any, may be up to an amount less than 50% by mass. For instance, it may be used in an amount in the range of 1-10% by mass.

[0032] To reduce the cost, it is preferable to add a translucent filler as component (d). This may be an organic filler or an inorganic filler. Note in this regard that a filler such as calcium carbonate as used in US2004181007A1 will not work. Component (d) may be selected from one or more translucent fillers with an optical refractive index l(tiner) that is equal to the optical refractive index of the composition of the product, l(prOduct), plus or minus 0.05, still more preferably selected from powdered polyacrylates, polymethacrylates, polyolefins, cellulose- based materials, silica or their mixtures. Moreover, the organic filler preferably has particle size distribution with D90 less than 100 pm so as to prevent settling or precipitation from the mixture. Preferred classes of fillers include polymethylmethacrylate (PMMA) and polypropylene (PP).

[0033] The amount of filler, if any, may be up to an amount of less than 80% by mass. For instance, it may be used in an amount in the range of 10-30% by mass.

[0034] In addition, the photocurable composition may comprise one or more adhesion promoters as component (e). The adhesion promoter ensures adhesion to the glass panes and to the spacer, if any. Whether an adhesion promoter is needed depends on the adhesive bond formed by the photocured composition. Preferably, the photocurable composition has adhesion strength of at least 0.3 MPa. Metal based adhesion promotors e.g., Chartsil™ or Chartwell™ range from Synthron, or Titanates and Zirconates may be used. Suitable adhesion promoters for photocurable acrylic sealant compositions may also be selected from, for instance, tackifying resins and / or silanes and silane-terminated polymers. A particularly suitable class of adhesion promoters includes vinylsilanes. Silane based adhesion promotors like an epoxy-silane (Silquest™ A-187, Momentive), an amino-silane (Dynasylan™ 1189, Evonik) or a methacrylate based silane (silane A-174, Momentive) may be used. For instance, this may be selected from di- or trialkoxyvinylsilanes, trialkoxymethacryloylalkylsilanes, and di- or trialkoxysilyl-terminated polymers. Some vinyl silane based adhesion promoters may co-react with component (a), and are therefore preferred. Preferably, vinyltrimethoxysilane (VTMO) can be used. A further alternative includes commercially available silane-terminated pre-polymers, e.g., from Wacker, Evonik, Kaneka, and Momentive. For instance, the silyl-terminated polymer marketed as Silyl™ SAX 400 from the Kaneka company may be used. In addition, MA-series (e.g. MA 490) or MAX- series (e.g. MAX 602) from Kaneka may be used.

[0035] The amount of adhesion promoter, if any, may be up to an amount of less than 10% by mass. For instance, it may be used in an amount in the range of 1-5% by mass.

[0036] Moreover, to achieve sufficient UV stability, the photocurable composition will comprise one or more UV stabilizers as component (f). It has been found that not all typical UV stabilizers perform adequately. In particular for compositions that are cured by UV radiation, the nature and amount of UV stabilizer must be optimised to avoid interference with the photoinitiator. Suitable examples of UV stabilizers are selected from one or more UV stabilizers that do not inhibit the curing process by absorption of the effective curing light wavelength or quenching of acrylate polymerization, still more preferably selected from non-phenol type UV stabilizers, still more preferably / V-(2-ethoxyphenyl)- / V’-(2-ethylphenyl)oxamide (Tinuvin™ 312 available from BASF) and similar oxalanilide-based UV-stabilizers.

[0037] The amount of these additive(s), may be up to an amount less than 3% by mass. For instance, a UV stabilizer or combination thereof may be used in an amount in the range of 0.3-1% by mass.

[0038] Furthermore, the photocurable composition may comprise one or more rheological additives as component (g). Suitable examples include organic thixotropes that allow for the light transmission during photocuring to the depth of up to 5 mm. Of these, the commercially available Thixatrol™ PM 8056 from Elementis is preferred.

[0039] The amount of rheological additives, if any, may be up to an amount of less than 5% by mass. For instance, it may be used in an amount in the range of 0.5-2% by mass.

[0040] As indicated, the photocurable composition may be a single component system (1 K), a 2 component system (2K) with e.g. the photoinitiator separated from the photocurable component, or even a multicomponent system. If a dual or multiple component system is used, then the components should be mixed prior to its use.

[0041] Typically, the edge seal composed of the secondary acrylic sealant composition is, upon curing, in the form of a layer having a thickness in the range of 1 to 5 mm. The layer thickness preferably is 3±1 mm. Upon curing it preferably has a Shore A hardness that is in the range of 25 to 70, more preferably 45 to 70, measured according to EN 1279-6:2016. Moreover, preferably the acrylic sealant composition, upon curing, has water vapour transmission rate for a 2 mm film no greater than 2.7 g / (m224h), measured according to EN 1279-4:2018 (Annex D.1). In addition, the acrylic sealant composition, upon curing, has argon gas permeation rate for 2 mm film no greater than 0.64 g / (m224h), as measured according to EN 1279-4:2018 (Annex D.2).

[0042] The photocurable composition according to the present invention can be applied directly onto a glass pane and / or onto a spacer. Curing of the photocurable composition is effected by irradiation, more preferably at the visible or near-ultraviolet wavelength range, still more preferably between 380 and 410 nm. Curing may, for instance, be effected at 385-400 nm wavelength using an Onforu™ 50W LED floodlight or another appropriate light source at, for instance, 10 cm distance. Irradiation time depends on the nature and amount of the photoinitiator and intensity of the light source. Initiation may already start after a few milliseconds. For instance, the irradiation time may be in the range of 1 to 60 seconds, for instance, 5 to 25 s, preferably about 15 s at each 10 cm segment of edge seal. However, irradiation may also be performed simultaneously, for instance in a UV cabinet, in a tunnel or similar station.

[0043] The method for preparing the edge seal according to the present invention therefore comprises the following steps:

[0044] (i) attaching a spacer on appropriately sized glass pane;

[0045] (ii) attaching another glass pane to the spacer, forming a cavity that may be filled with inert gas or a gas that is denser than air, and forming an outer edge gap, optionally repeating these steps for obtaining multi-pane insulating glass units;

[0046] (iii) filling the outer edge gap between spacer(-s) and glass panes with uncured acrylic sealant composition as defined herein above, and

[0047] (iv) curing the acrylic sealant composition, preferably by irradiation, more preferably at the visible or near-ultraviolet wavelength range, e.g., between 380 and 410 nm.

[0048] The photocurable composition may also be used for the preparation of solar modules. This can be achieved, for instance, according to the following steps:

[0049] (i) spreading a layer of photocurable acrylic sealant composition on glass;

[0050] (ii) positioning of solar cells on the sealant composition layer with sunward face down;

[0051] (iii) electrically connecting the cells into circuit;

[0052] (iv) spreading a layer of sealant composition on the back side of cells and circuits;

[0053] (v) placing a second transparent sheet, such as glass, on the back side of the panel;

[0054] (vi) curing of the acrylic sealant composition by irradiation through glass with visible or near-ultraviolet light, e.g., between 380 and 410 nm. The present invention also results in dedicated assembly line for IGUs comprising:

[0055] 1) a station for glass cutting, edge preparation and / or removal of protective coating, washing and drying;

[0056] 2) a station for the application of a spacer and / or frame;

[0057] 3) a station for pressing glass panes together, preferably under an inert gas atmosphere;

[0058] 4) a station for application of the photocurable acrylic sealant composition, and

[0059] 5) a station for photocuring the photocurable acrylic sealant composition.

[0060] Likewise, the present invention provides a dedicated assembly line for solar modules comprising:

[0061] 1) a station for glass cutting, edge preparation, washing and drying;

[0062] 2) a station for the application of the photocurable acrylic sealant composition onto a glass pane, which may also be used for coating of solar cells and circuits with photocurable acrylic sealant composition;

[0063] 3) a station for positioning solar cells on the sealant composition, wherein the sealant composition may be photocured through the glass;

[0064] 4) a station for electrically connecting cells in circuit;

[0065] 5) a station for placing a second glass pane or transparent sheet on the solar cells that have been coated with photocurable acrylic sealant composition, and

[0066] 6) a station for photocuring the photocurable acrylic sealant composition.

[0067] The current invention is illustrated by the attached examples.

[0068] Examples of photocurable acrylic sealant composition

[0069] Various compositions were prepared according to the formulations set out in Table 1.

[0070] Table 1

[0071] Example 1, Procedure for the preparation of a photocurable acrylic sealant composition. Propoxylated neopentyl glycol diacrylate (commercially available as Sartomer™ SR9003 from Arkema) (900 g), acrylated epoxidized soybean oil (400 g), diisononyl phthalate (100 g), and vinyltrimethoxysilane (Dynasylan™ VTMO) (80 g) were charged into a 4 L vessel and stirred at 25°C. Dibenzyl (2,4,6-trimethylbenzoyl)phosphine oxide (60 g) was added to the stirred mixture, followed by Tinuvin™ 312 (20 g) and Thixatrol™ PM 8056 (40 g). The suspension was stirred at the same temperature for 30 min while protecting from light, then polypropylene powder (400 g) was added and the mixture was stirred for further 30 min.

[0072] Examples 2-4

[0073] The procedure as set out in Example 1 was followed, but now with the formulations of Examples 2, 3, and 4, as set out in Table 1.

[0074] Example 5, Application of the photocurable acrylic sealant composition on a glass pane The photocurable acrylic sealant composition formulation according to Examples 1-4 was applied around the outer edge of aluminium spacer bar while constructing an insulating glass unit. The layer thickness was 3±1 mm. Curing of the outer sealant composition was effected by irradiation at 385-400 nm wavelength using an Onforu™ D50LIV 50W LED floodlight at 10 cm distance. Irradiation time was 15 s at each 10 cm segment of edge seal. The resulting cured sealant composition reached Shore A hardness of 70 immediately after irradiation. Comparative Examples 6-8

[0075] A photocurable acrylic sealant composition formulation according to Example 1 was prepared, but now applying the UV stabilizer and filler employed in US2004181007A1. The sealant composition were applied on a glass pane, similar to Example 5. The results are in Table 2. What is immediately apparent, is that the compositions do not provide sufficient depth of cure for the application as secondary sealant, as illustrated by Example 5.

[0076] Table 2

[0077] The production time when applying the compositions according to the present invention therefore compares favourably to that of a conventional edge seal using commercially available two-component polyurethane or polysulphide sealant compositions where for a similar IG unit typically at least 3 hours are required to reach Shore A hardness of at least 45. Since the 3 hour curing time with Pll and PS sealant compositions is comparable to the time required for all other basic operations at IGU factory (glass cutting, washing, drying, spacer bending, desiccant filling, butylation, assembly of IGU, gas filling and secondary sealant composition application), about one half of IGU factory floor is typically reserved for stands containing IGUs during the curing process. By elimination of the slow curing chemistry, it is possible to free up to one half of the factory floor, reduce facility size or double the productivity at existing facilities. The use of a one-component sealant composition described in this invention eliminates possibilities for mechanical failure or damage of IGUs during curing, prevents loss of product due to incorrect mixing ratio of two-component sealant compositions, prevents stoppage of production line due to chemical curing of two-component sealant compositions inside the sealant composition application machinery, and avoids the contact toxicity of isocyanates typically used in polyurethane sealant compositions. Immediate curing of photocurable acrylics enables immediate quality control and shipment of the finished IGUs, providing an opportunity for superior implementation of just-in-time inventory strategy at IGU factories.

Claims

CLAIMS1. Edge seal for manufacturing two-pane or multi-pane insulating glass or solar modules, comprising at least one photocured acrylic sealant composition as secondary sealant.

2. The edge seal of claim 1, wherein the photocured acrylic sealant composition is isocyanate free and its curing is achieved by photocuring, preferably at 380-470 nm wavelength.

3. The edge seal of any one of the preceding claims, wherein the acrylic sealant composition, upon curing, has a Shore A hardness that is in the range of 45 to 70, measured according to EN 1279-6:2016.

4. The edge seal of any one of the preceding claims, wherein the acrylic sealant composition, upon curing, is in the form of a layer having a thickness in the range of 1 to 10, preferably 1 to 5 mm.

5. The edge seal of any one of the preceding claims, wherein the photocured acrylic sealant composition comprises an oxalanilide-based UV absorbent, preferably / \ / -(2- ethoxyphenyl)- / V’-(2-ethylphenyl)oxamide.

6. The edge seal of any one of the preceding claims, wherein the photocured acrylic sealant composition comprises one or more fillers, wherein the filler(s) are translucent.

7. The edge seal of any one of the preceding claims, further comprising a spacer and / or a primary sealant composition.

8. The edge seal of any one of the preceding claims, wherein the photocured acrylic sealant composition is obtained by curing a photocurable compound containing one or more acryl or methacryl functional groups and a photoinitiator by light irradiation at 380-470 nm wavelength.

9. The edge seal of claim 8, wherein the photocurable acrylic sealant composition has the following overall composition: a) 20%-99%, preferably 40-70%, most preferably 50-65% by mass, of one or more photocurable compounds; b) less than 5%, preferably 0.4-4.6% by mass of one or more photoinitiators; c) optionally one or more plasticizers; d) optionally one or more fillers, which must be translucent if present; e) optionally one or more adhesion promoters; f) less than 3% by mass of one or more UV stabilizers; and g) optionally one or more rheological additives, adding up to 100% by mass.

10. The edge seal of claims 9, wherein component (a) is selected from alkyl esters of acrylic or methacrylic acid, aliphatic urethane diacrylates, polyether polyacrylates, epoxidizedfatty acid triglyceride polyacrylates, such as acrylated epoxidized soybean oil, acryl or methacryl-derivatized non-hydrogenated polydienes, such as acryl- or methacryl- functionalized polybutadiene, preferably propoxylated neopentyl glycol diacrylate and acrylated epoxidized soybean oil, or a mixture thereof.

11. The edge seal of any one of claims 9-10, wherein component (b) is selected from one or more photoinitiators that are suitable for inducing the polymerization of acrylates upon irradiation with visible or near-ultraviolet light, preferably at a wavelength range between 300 and 450 nm, more preferably between 380 and 410 nm, more preferably (2,4,6- trimethylbenzoyl) diphenylphosphine oxide.

12. The edge seal of any one of claims 9-11 , wherein component (c) is present in an amount less than 50%, preferably 1-10% by mass, and preferably selected from one or more of alkyl, aralkyl or mixed phthalate, alkyl or aralkyl terephthalate, alkyl or aralkyl benzoate or dibenzoate, still more preferably dialkyl phthalate wherein the alkyl substituents each contain at least 9 carbon atoms.

13. The edge seal of any one of claims 9-12, wherein component (d) is present in an amount of less than 80%, preferably 10-30% by mass, more preferably selected from one or more translucent fillers with an optical refractive index l(tiner) that is equal to the optical refractive index of the composition of the product, l(prOduct), plus or minus 0.05, still more preferably selected from powdered polyacrylates, polymethacrylates, polyolefins, cellulose- based materials, silica or their mixtures.

14. The edge seal of any one of claims 9-13, wherein component (e) is present in an amount less than 10%, preferably 1-5% by mass, more preferably selected from one or more adhesion promoters effective for creating chemical bonding between polyacrylates and glass or metal surfaces, still more preferably selected from di- or trialkoxyvinylsilanes, trialkoxymethacryloylalkylsilanes, and di- or trialkoxysilyl-terminated polymers.

15. The edge seal of any one of claims 9-14, wherein component (f) is present in an amount of 0.3-1% by mass, more preferably selected from one or more UV stabilizers that do not inhibit the curing process by absorption of the effective curing light wavelength or quenching acrylate polymerization, still more preferably selected from non-HALS and nonphenol type UV stabilizers, still more preferably / V-(2-ethoxyphenyl)- / V’-(2- ethylphenyl)oxamide.

16. The edge seal of any one of claims 9-15, wherein component (g) is present in an amount of less than 5%, preferably 0.5-2%, more preferably selected from organic thixotropes.

17. The edge seal of any one of the preceding claims, wherein the acrylic sealant composition, upon curing, has a water vapour transmission rate for a 2 mm film that is no greater than 2.7 g / (m224h), measured according to EN 1279-4:2018 (Annex D.1).

18. The edge seal of any one of the preceding claims, wherein the acrylic sealant composition, upon curing, has an argon gas permeation rate for 2 mm film that is no greater than 0.64 g / (m224h), as measured according to EN 1279-4:2018 (Annex D.2).

19. A photocurable acrylic sealant composition comprising components a) - b), and optionally c) - g) of any one of claims 9-16.

20. Use of the edge seal according to claims 1-18, for manufacturing insulating glass for windows, conservatories, structural glazing and roof glazing; for glazing in landbound vehicles, watercraft and aircraft, or for fabricating solar modules.

21. Method for preparing the edge seal according to any one of claims 1-18, comprising the following steps:(i) attaching a spacer and / or a primary sealant composition on appropriately sized glass pane;(ii) attaching another glass pane to the spacer, forming a cavity that may be filled with inert gas or a gas that is denser than air, and forming an outer edge gap, optionally repeating these steps for obtaining multi-pane glass units;(iii) filling the outer edge gap between spacer(-s) and glass panes with uncured acrylic sealant composition with a composition according to any one of claims 1-11 , and(iv) curing the acrylic sealant composition, preferably by irradiation, more preferably at the visible or near-ultraviolet wavelength range between 300 and 450 nm, preferably between 380 and 410 nm.

22. Two-pane or multi-pane insulating glass or solar modules provided with an edge seal as claimed in any one of claims 1-18.

23. Assembly line for producing the two-pane or multi-pane insulating glass or solar modules as claimed in claim 22, comprising one or more stations for applying the photocurable acrylic sealant composition for use as secondary seal and comprising one or more stations for photocuring the photocurable acrylic sealant composition.

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