Reactive liquid plastics containing expandable graphite

Abstract

Reactive liquid plastic for roof waterproofing comprising expanded graphite in an amount of 2 wt% to 15 wt%, wherein the liquid plastic is based on or consists of a one-component polyurethane liquid plastic based on alkoxysilane-functionalized polyurethanes and curing by silane polycondensation.

Description

The invention relates to reactive liquid plastics containing expandable graphite and their use in the production of intumescent roof waterproofing. The future demand for photovoltaic systems on flat roofs is emerging as an urgent necessity, significantly influenced by climate change, rising energy prices, and stricter legal requirements. This demand extends to both existing buildings and newly constructed structures. In light of these developments, the installation of photovoltaic systems on flat roofs is becoming an indispensable measure to meet the steadily increasing energy demand while simultaneously reducing the ecological footprint. New buildings offer the opportunity to integrate photovoltaic systems with particular attention to preventative fire protection, ensuring long-term and safe operation. However, renovations present a challenging situation: while the fire safety regulations in effect at the time of construction are adhered to during the renovation, this is done entirely without considering the additional risks associated with the operation of retrofitted photovoltaic systems. These risks are considerable, as a short circuit can lead to prolonged arc discharges, which can cause fires. With regard to fire spread, flat roofs with bituminous roofing membranes are particularly critical, especially if flammable insulation materials are also present. For existing flat roofs where gravel cannot be applied for structural reasons, there are currently no options for retrofitting with photovoltaic elements while complying with current fire protection guidelines. The object of the present invention was therefore to provide improved roof sealing materials for optimizing fire protection for the subsequent installation of photovoltaic elements. This object was achieved by providing the liquid plastics described in more detail below. The present invention relates to reactive liquid plastics for roof waterproofing in accordance with EOTA guideline ETAG 005, characterized in that they contain 2 to 10 wt% of expandable graphite. The present invention also relates to a method for producing intumescent roof waterproofing. Within the scope of the present invention, the surprising observation was made that, using the liquid plastics described in more detail below, roof seals with intumescent properties can be produced that can protect the underlying roof structure very efficiently from fire and reliably prevent fire spread. In corresponding fire tests, it was demonstrated that the protective effect of the intumescent roof seals is sufficient to reliably protect even fire-critical structures from fire spread. This makes it possible to optimize any existing roof structure from a fire protection perspective in such a way that the safe operation of photovoltaic systems on these roof structures becomes possible. In state-of-the-art liquid plastics, aluminum hydroxide and magnesium hydroxide are predominantly used as solid flame retardants. The potential use of expandable graphite in reactive liquid plastics—preferably in combination with aluminum hydroxide and magnesium hydroxide—for the production of intumescent, liquid-applied roof waterproofing membranes is not yet known. The more recent WO 2022 247993 A1 describes two-component sealing materials consisting of an aqueous polymer dispersion and a mineral binder system. While expandable graphites and aluminum hydroxide are mentioned generally as flame retardants used in the formulation, the binders described in this publication are aqueous coating products that are sensitive to frost and problematic for thick-film applications due to significant shrinkage caused by water evaporation. This publication contains no reference to the inventive combination of reactive liquid plastics with selected expandable graphites. The liquid plastics usable according to the invention, which can be additively treated with expandable graphite during formulation or subsequently, are known per se, largely solvent-free, reactive roof waterproofing materials of the prior art, which comply with the EOTA guideline ETAG 005 (Guideline for European Technical Approval for liquid-applied roof waterproofing). Materials suitable according to the invention are applied to the roof in liquid form and harden by radical polymerization, polyaddition, or silane polycondensation under ambient conditions. In principle, the EOTA guideline ETAG 005 also defines the minimum fire protection requirements with reference to EN 13501-1. Within the scope of the present invention, it has been shown that the intumescent roof waterproofing systems that can be produced using the liquid plastics according to the invention significantly exceed these minimum requirements. Liquid plastics based on unsaturated acrylate copolymers can be used according to the invention, for example. Such liquid plastics typically contain significant amounts of methyl methacrylate, unsaturated acrylate and / or methacrylate copolymers, and optionally further esters of acrylic acid and / or methacrylic acid. Curing occurs via radical polymerization, which is initiated by the addition of organic peroxides, in particular dibenzoyl peroxide. Liquid plastics based on unsaturated acrylate copolymers are described by way of example in Korean patent specification KR101192384 B1 or WO2021181117A1. Suitable liquid plastics based on polyurethanes are preferred. These are the known one- and two-component coating compounds based on aromatic and / or aliphatic polyisocyanates with polyols and / or polyamines. For example, one-component polyurethane liquid plastics based on isocyanate prepolymers, which cure upon exposure to atmospheric moisture by forming urea, are suitable. Also suitable are one-component polyurethane liquid plastics containing polyoxazolidines, polyaldimines, and / or polyketimines in addition to polyisocyanates and polyisocyanate prepolymers. Such one-component polyurethane systems are described in WO2016005457A1, WO2014114640A1, WO2014114642A1, WO2014114643A1, and WO2014114641A1. Particularly suitable one-component polyurethane liquid plastics are based on alkoxysilane-functionalized polyurethanes and cure by silane polycondensation. Such alkoxysilane-functionalized polyurethanes are described by way of example in EP-A 1 987 108, EP-A 2 352 776 and EP-A 2 561 024 as well as WO 2019 114990 A1 and can optionally also be formulated as two-component materials, as described by way of example in EP4063421A1. Preferred two-component liquid plastics based on polyurethanes consist of a polyisocyanate component and a polyol component and / or a polyamine component. Suitable examples include two-component liquid plastics based on diphenylmethane diisocyanate and optionally modified castor oil, as well as liquid plastics based on aromatic and / or aliphatic polyisocyanate prepolymers with aromatic amines such as diethyltoluenediamine or dimethylthiotoluenediamine. Particularly preferred are two-component polyurethane liquid plastics based on aliphatic polyisocyanates and polyaspartic acid esters, as described, for example, in EP3115388B1 or WO2022253635A1. To produce the liquid plastics according to the invention, the liquid plastics described above are additively treated during formulation or subsequently with expandable graphite intercalation compounds, which are known as expandable graphite and are commercially available. These are compounds that contain foreign components – intercalates – embedded between the lattice layers of the graphite. Such expandable graphite intercalation compounds are usually produced by dispersing graphite particles in a solution containing an oxidizing agent and the gas compound to be incorporated. Commonly used oxidizing agents include nitric acid, potassium chlorate, chromic acid, potassium permanganate, hydrogen peroxide, and the like. Concentrated sulfuric acid is frequently used as the compound to be incorporated, as described, for example, in EP0085121A1.Expandable graphite is a well-known flame retardant additive widely used in coatings and sealants for fire protection. EP3004197A1 is one example of an application as an expanding sealant. According to the invention, known intercalated compounds of SOx, NOx, halogens, and / or acids in graphite can be used as expandable graphites. Preferably, expandable graphites are those that release SO2, SO3, NO, and / or NO2 upon expansion at a starting temperature of 150 to 300°C, preferably 180 to 230°C. Preferred expandable graphites have a medium grain size distribution, with 80% of the grains having a grain size >100 µm, preferably >150 µm. Particularly preferred types of expandable graphite contain no blowing agent and have a volume of expansion of more than 100 cm³ / g (1000°C), preferably more than 200 cm³ / g (1000°C). According to the invention, the above-characterized expandable graphites are used in amounts of 2 to 15 wt%, preferably 3 to 9 wt%, particularly preferably 4 to 8 wt% based on the total weight of the liquid plastic. The incorporation of the expandable graphite into the liquid plastics usable according to the invention is typically carried out by dispersion using a rotary dissolver. Here, the expandable graphite is preferably incorporated towards the end of the dispersion process, i.e., after the addition of all other fillers and pigments at low rotational speed. The liquid plastics obtained according to the invention in this way exhibit only a slightly altered rheological behavior, in particular only a slightly increased viscosity. Therefore, it is possible to subsequently equip liquid plastics suitable for the invention with expandable graphite. The present invention also relates to a method for producing intumescent roof seals by applying reactive liquid plastics in combination with a textile fabric. The application of the liquid plastics according to the invention is carried out in such a way as to comply with the conditions of the EOTA guideline ETAG 005. For this purpose, the liquid plastics according to the invention are applied as a one-component or two-component material to a cleaned roof surface that has optionally been pre-treated by sanding or priming, in accordance with the processing instructions. In a first layer, typically 1.3 kg / m² to 2 kg / m² of liquid plastic is applied by brushing, rolling, or squeegeeing. A textile fabric (nonwoven reinforcement) is then embedded in the reacting liquid plastic. Textile fabrics are defined as all knitted, crocheted, woven, braided, or otherwise fabricated structures made from yarns or fibers.Suitable textile fabrics are based on organic or inorganic fibers, such as glass fibers, carbon fibers, or plastic fibers, such as polyester, polyamide, aramid, or polyacrylate fibers, metal fibers, or fibers with metallic components, or the like. Nonwoven materials such as glass fiber nonwovens or polyester nonwovens are preferably used, with glass fiber nonwovens being particularly preferred. A second layer of the liquid plastic according to the invention is applied to the textile fabric, typically again in an amount of 1.3 kg / m² to 2 kg / m². Within the scope of the present invention, it has proven advantageous if the first layer of liquid plastic contains less expandable graphite than the second layer. Corresponding fire tests have shown that in these cases, the coating cracks less severely, thus allowing less oxygen to reach underlying, fire-prone layers. In a particular embodiment of the present invention, the first layer of liquid plastic contains no expandable graphite (i.e., the unmodified liquid plastic according to the invention), while only the second layer contains the liquid plastic according to the invention, containing expandable graphite as described above. In this case, the liquid plastics of the first and second layers differ only in their expandable graphite content. The roof waterproofing is generally applied in such a way that a minimum thickness of 2 mm of the cured coating is achieved. The present invention also relates to the use of the liquid plastics according to the invention for the production of intumescent roof waterproofing in accordance with the EOTA guideline ETAG 005. The composition of the liquid plastics according to the invention and their processing are fundamentally designed to fully meet the requirements of the EOTA guideline ETAG 005, so that the fire-protection-optimized roof constructions have a projected service life of 25 years. Furthermore, the fire-protection-optimized roof constructions comply with current fire protection requirements and are therefore ideally suited for the subsequent installation of photovoltaic systems. Examples Example 1 (not according to the invention) Commercially available one-component liquid plastic based on a silane-terminated polyurethane containing 19 wt% aluminum trihydroxide (Frankosil®1K PLUS from Franken Systems GmbH, Gollhofen). Example 2 (not according to the invention) Commercially available two-component liquid plastic based on aliphatic polyisocyanates and polyaspartic acid esters (Revopur WP200 from Franken Systems GmbH, Gollhofen). The polyaspartic acid ester component of the polyurethane liquid plastic contains 15 wt% aluminum trihydroxide. Example 3 (not according to the invention) A one-component polyurethane liquid plastic produced according to Example 1, WO 2014114642 A1 . Example 4 (not according to the invention) A commercially available liquid plastic based on polymethyl methacrylate (Triflex ProDetail® from Triflex GmbH & CoKG, Minden) that can be cured using peroxide. Example 5 (according to the invention) In a commercially available one-component liquid plastic based on a silane-terminated polyurethane containing 19 wt% aluminum trihydroxide (Frankosil®1K PLUS from Franken Systems GmbH, Gollhofen), 5 wt% expandable graphite (BLG 250T from RMC Remacon GmbH, Säckingen, starting temperature 200°C, expansion rate >200cm3 / g (1000°C), particle size distribution 80% >250µm) is incorporated by means of a rotary dissolver at low speed. Example 6 (according to the invention) In the polyaspartic acid ester component of a commercially available polyurethane liquid plastic based on aliphatic polyisocyanates and polyaspartic acid esters containing 15 wt% aluminum trihydroxide (Revopur WP200 from Franken Systems GmbH, Gollhofen), 5 wt% expandable graphite (BLG 250T from RMC Remacon GmbH) is incorporated by means of a rotary dissolver at low speed. Example 7 (according to the invention) 6 wt% expanded graphite (BLG 300TS from RMC Remacon GmbH, Säckingen, starting temperature 180°C, expansion rate >400cm3 / g (1000°C), particle size distribution 80% >300µm) is incorporated into a one-component polyurethane liquid plastic produced according to Example 1, WO 2014114642 A1 using a rotary dissolver at low speed. Example 8 (according to the invention) 6 wt% of expandable graphite type Ex 180 from NGS Trading & Consulting GmbH, Leinburg (starting temperature 185°C, expansion rate approx. 320 cm3 / g (1000°C), particle size distribution 90% >180µm) are incorporated into the resin component of a commercially available liquid plastic based on polymethyl methacrylate (Triflex ProDetail® from Triflex GmbH & CoKG, Minden) using a rotary dissolver at low speed. Example 9 (according to the invention) In a one-component liquid plastic based on a silane-terminated polyurethane, produced according to WO2011131506A1 Example 1, with the modification that the amount of aluminium trihydrate was reduced to 5 wt%, 9 wt% expandable graphite (BLG 250T from RMC Remacon GmbH, Säckingen, starting temperature 200°C, expansion rate >200cm3 / g (1000°C), particle size distribution 80% >250µm) is incorporated by means of a rotary dissolver at low speed. Example 10 (according to the invention) In a one-component liquid plastic based on a silane-terminated polyurethane, manufactured according to WO2011131506A1 Example 1, with the modification that the amount of aluminium trihydrate was reduced to 1 wt%, 12 wt% expandable graphite (BLG 250T from RMC Remacon GmbH, Säckingen, starting temperature 200°C, expansion rate >200cm3 / g (1000°C), particle size distribution 80% >250µm) is incorporated by means of a rotary dissolver at low speed. Example 11 (not according to the invention) A polyurethane liquid plastic based on aliphatic polyisocyanates and polyaspartic acid esters containing 41 wt% aluminium trihydroxide, produced according to EP3115388B1 Example 8. Example 12 (according to the invention) A polyurethane liquid plastic based on aliphatic polyisocyanates and containing polyaspartic acid esters, produced according to EP3115388B1 Example 8, in which the amount of aluminium trihydroxide in the polyaspartic acid ester component has been reduced to 30 wt%, is incorporated with 3 wt% expandable graphite (BLG 250T from RMC Remacon GmbH) by means of a rotary dissolver at low speed. Example 13: Fire tests (not according to the invention) Suspended from a holding device, the 20 x 30 cm sample areas to be tested are exposed to a flame for 10 minutes using a standard hand-held torch (butane torch from Tom) at a distance of 5 cm and a flame temperature of approximately 1300°C. The test is then subjected to a fire test. The fire test is terminated prematurely as soon as the bitumen membrane begins to burn. The relevant fire tests were evaluated according to the following criteria. -No longer intact after a very short time, may continue to burn on its own. Short-term resistance to flame, low fire-retardant effect +Good resistance to flames, good fire-retardant effect ++Very high resistance to flame exposure, pronounced fire-retardant effect, seal intact after test. Fire tests example series 1 (not according to the invention) In accordance with Example 13, the following commercially available roofing membranes were subjected to a fire test. Example 14PVC (Bauder Thermofol U)- Example 15FPO (Bauder Thermoplan T)- Example 16 Bitumen (BauderKARAT)- Fire tests, example series 2 to 4 (according to the invention) Approximately 170 g of a liquid plastic is evenly applied to various substrates measuring approximately 20 x 30 cm using a squeegee. The average thickness of the resulting coating is 2.3 ± 0.3 mm. The resulting sample structures are stored for 28 days at an ambient temperature of 20°C and then subjected to a fire test, as described in Example 13. Combination of Example 14 and evaluation; Combination of Example 15 and evaluation; Combination of Example 16 and evaluation Example 1 - Example 1 - Example 1 - Example 2 - Example 2 - Example 2 - Example 3 - Example 3 - Example 3 - Example 4 - Example 4 - Example 4 - Example 5++Example 5++Example 5++ Example 6++Example 6++Example 6++ Example 7++Example 7++Example 7++ Example 8++Example 8++Example 8++ Example 90. Example 90. Example 90 Example 10+ Example 10+ Example 10+ Example 110. Example 110. Example 110 Example 12+ Example 12+ Example 12+ Fire tests, example series 5 to 8 (according to the invention) On a plastic sheet (e.g., 15) measuring approximately 20 x 30 cm, about 85 g of a liquid plastic are evenly applied by spreading it with a squeegee. A fleece is placed into the reacting compound and carefully pressed down so that the underside is evenly coated with the reacting compound. Then, another 85 g of the reacting compound is applied to the top side of the fleece and evenly spread with a squeegee. The average thickness of the resulting fleece-reinforced seal is 2.3 ± 0.3 mm. Examples of nonwoven fabric (not according to the invention) Example 17: Polyester nonwoven fabric with a basis weight of 110g / m² (FrankolonVlies, from the company Franken Systems Gollhofen) Example 18: Polyester nonwoven fabric with a basis weight of 165g / m² (Frankolon nonwoven fabric, from the company Franken Systems Gollhofen) Example 19: Glass fleece with a basis weight of 225g / m² (QUALITYGFM225MMT, from the company Hagulan, Fulda) Example 20: Aramid nonwoven fabric with a basis weight of 50 - 100g / m² (Spunlace, from Norafin, Mildenau) The resulting sample structures are stored for 28 days at an ambient temperature of 20°C and then subjected to a fire test, according to Example 13. Example 1 - Example 1 - Example 10 - Example 10 Example 2 - Example 2 - Example 20 - Example 20 Ex. 5++Ex. 5++Ex. 5+Ex. 5+ Ex. 6++Ex. 6++Ex. 6+Ex. 6+ Ex. 110Ex. 110Ex. 110Ex. 110 Fire tests, example series 9 and 10 (according to the invention) On a plastic sheet (Example 15), measuring approximately 20 x 30 cm, about 85 g of a liquid plastic with a low content of, or without, expandable graphite is evenly applied by spreading it with a squeegee. A fleece is placed into the reacting mass and carefully pressed down so that the underside is evenly coated with the reacting mass. Then, another 85 g of a liquid plastic containing expandable graphite is applied to the top of the fleece and evenly spread with a squeegee. The average thickness of the fleece-reinforced seal produced in this way is 2.3 ± 0.3 mm. The resulting sample structures are stored for 28 days at an ambient temperature of 20°C and then subjected to a fire test, as described in Example 13. First layer of liquid plastic: Example 1++First layer of liquid plastic: Example 1++ Second layer of liquid plastic: Example 5 First layer of liquid plastic: Example 2++First layer of liquid plastic: Example 2++ Second layer of liquid plastic: Example 6 QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature WO 2022 247993 A1

[0009] KR 101192384 B1

[0012] WO 2021181117A1

[0012] WO 2016005457A1

[0013] WO 2014114640A1

[0013] WO 2014114642A1 [0013, 0028, 0032]WO 2014114643A1

[0013] WO 2014114641A1

[0013] EP-A 1 987 108

[0014] EP-A 2 352 776

[0014] EP-A 2 561 024

[0014] WO 2019 114990 A1

[0014] EP 4063421A1

[0014] EP 3115388B1 [0015, 0036, 0037]WO 2022253635A1

[0015] EP 0085121A1

[0016] EP 3004197A1

[0016] WO 2011131506A1 [0034, 0035]

Claims

Reactive liquid plastic for roof waterproofing comprising expandable graphite in an amount of 2 wt% to 15 wt%, wherein the liquid plastic is based on or consists of a one-component polyurethane liquid plastic based on alkoxysilane-functionalized polyurethanes and curing by silane polycondensation. Reactive liquid plastic according to claim 1, comprising an amount of 3 wt% to 9 wt% of expandable graphite. Reactive liquid plastic according to claim 1, comprising an amount of 4 wt% to 8 wt% of expandable graphite. Reactive liquid plastic according to one of claims 1 to 3, characterized in that the expandable graphite has a grain size in the range of 50 µm to 600 µm. Reactive liquid plastic according to one of claims 1 to 4, characterized in that the expandable graphite has a proportion of 80% to 90% of the grain size in the range of 50 µm to 600 µm. Reactive liquid plastic according to one of claims 1 to 4, characterized in that the expandable graphite has a proportion of the grain size in the range of 80% < 75 µm to 80% > 500 µm. Reactive liquid plastic according to claim 4, characterized in that the expandable graphite does not contain a blowing agent. Reactive liquid plastics according to one or more of claims 1 to 7, characterized in that further comprising aluminium trihydroxide. Reactive liquid plastics according to claim 8, characterized in that further comprising aluminium trihydroxide in an amount of 5 wt% to 50 wt%. Reactive liquid plastics according to one or more of claims 1 to 9, characterized in that the reactive liquid plastic comprises one- or two-component polyurethanes. Reactive liquid plastics according to claim 10, characterized in that the liquid plastic comprises a two-component polyurethane based on aliphatic polyisocyanates and polyaspartic acid esters. Reactive liquid plastics according to one or more of claims 1 to 11, characterized in that the reactive liquid plastic comprises a silylated polyurethane. Intumescent roof waterproofing comprising a reactive liquid plastic according to one or more of claims 1 to 12 and a textile fabric. Intumescent roof waterproofing according to claim 13, wherein the textile fabric is a glass fleece. Intumescent roof waterproofing according to claim 13 or 14, characterized in that the liquid plastic is applied in a first layer and in a second layer, wherein the first layer contains less expandable graphite than the second layer. Intumescent roof waterproofing according to claim 13 or 14, characterized in that the liquid plastic in the first layer does not comprise expandable graphite.