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Synthetic Polymer Waterproofing Membrane with Self-Repair Properties

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Synthetic Polymer Waterproofing Membrane with Self-Repair Properties (19) TZZ¥_Z_T (11) EP 3 106 489 A1 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.: 21.12.2016 Bulletin 2016/51 C08J 5/18 (2006.01) C08K 3/34 (2006.01) C09K 3/10 (2006.01) C08L 23/02 (2006.01) (2006.01) (21) Application number: 15382320.8 E04B 1/66 (22) Date of filing: 16.06.2015 (84) Designated Contracting States: • Carreras Torres, Emilio AL AT BE BG CH CY CZ DE DK EE ES FI FR GB 18230 Atarfe - Granada (ES) GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO • Hidalgo Betanzos, Joaquin PL PT RO RS SE SI SK SM TR 20730 Azpeitia (Guipúzcua) (ES) Designated Extension States: • Garmendia Barrena, Maria Izascun BA ME 20730 Azpeitia - Guipúzcoa (ES) Designated Validation States: MA (74) Representative: Carlos Hernando, Borja Garrigues IP, S.L.P. (71) Applicant: Atarfil, S.L. Hermosilla, 3 18230 Atarfe Granada (ES) 28001 Madrid (ES) (72) Inventors: • Martín Sevilla, Gabriel 18230 Atarfe - Granda (ES) (54) SYNTHETIC POLYMER WATERPROOFING MEMBRANE WITH SELF-REPAIR PROPERTIES (57) Synthetic polymer waterproofing membrane with self-repairing properties refers to a self-repairing synthetic waterproof membrane, applicable in the construction sector. This membrane can be monolayer or multilayer. The com- position of the membrane includes thermoplastic polymers, smectite-type clays and super water-absorbent polymers. EP 3 106 489 A1 Printed by Jouve, 75001 PARIS (FR) EP 3 106 489 A1 Description Object of the invention 5 [0001] The present invention, a synthetic polymer waterproofing membrane with self-repair properties, refers to a synthetic membrane applicable in the construction sector. This membrane can be monolayer or multilayer. The compo- sition of the monolayer membrane comprises thermoplastic polymers, smectite-type clay materials and super absorbent polymers (SAP). In addition, the multilayer membrane consists of at least three layers, the outer layers having a com- position similar to those existing at present and the inner layer with a composition as specified above. 10 [0002] The present invention, self-repairing synthetic membrane is applicable to the field of building works, in the waterproofing of roofs and underground structures (floors, walls...) and, in the field of civil works, in the sealing of landfi lls, canals, tunnels, water deposits, roads, walls, bridges... Description of the Prior Art 15 [0003] Synthetic materials (polymers) are currently used for the manufacture of waterproofing membranes such as: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), ethylene propylene diene monomer (EPDM), bitu- men...and/or combinations thereof which are mixed with small proportions of additives. [0004] Combinations of different geosynthetic materials are also used, such is the case of "bentonite blankets" which 20 are made from geocomposites, i.e. products formed by the combination of different geosynthetic materials, for example geotextile-bentonite-geotextile, geotextile-bentonite-plastic membrane, etc., all of which contain bentonite powder trapped between other layers of geosynthetics, thereby obtaining bentonite-based waterproofing systems for building and civil engineering works. [0005] These synthetic or natural raw materials (PE, PP, PVC, EPDM, bitumen...) are employed as raw materials for 25 the manufacture of waterproofing membranes for installation at works which must have the following properties: high degree of water resistance, excellent mechanical properties, and high durability, among others. Existing waterproofing membranes feature extremely low water absorption capacity and, owing to this feature they are used for these applica- tions. On the other hand, they do not present any absorption effect and, therefore, swelling upon contact with water. [0006] One of the major limitations of waterproofing membranes is their total inability to maintain their water-tightness 30 once they are broken, since they are unable to stop the leakage of the fluid they contain once this break has occurred. [0007] Different Bentonite-based solutions are also used as waterproofing barriers both for civil engineering and building works applications, in addition to: • Bentonite grout or slurry to prevent subsidence in the construction of tunnels or for filling cracks. 35 • Bentonite-based waterproofing blankets, comprising a geomembrane (waterproofing membrane, with the main func- tion of supporting the affixed layer of bentonite) • Geocomposites comprising bentonite encapsulated between one or two layers of woven geotextile. [0008] In the state of the art this is known sodium bentonite, or Montmorillonite, which is a tri-laminar phyllosilicate 40 type of clay (FIG.1) of the smectite group whose structure is configured by the stacking of octahedral units mainly of aluminium in the form of a mesh, in between two planes of Silicon (Si) tetrahedra, which include the simple or hydrated compensation cations. [0009] The main structural feature of smectite-type clay is that both water and other polar molecules, including organic molecules, can penetrate the inter-laminar space causing an expansion of the mesh. This phenomenon is due to the 45 fact that the parallel sheets that make up this group of clays are joined by Van der Waals forces and other electrostatic forces. This structural design makes them ideal for acting as hydraulic barriers. In particular, the sodium bentonite family of clays are the most suitable for this application since they have the ability to expand their volume several times when they enter into contact with water, although calcium bentonites or mixtures of calcium and sodium are also used. [0010] Bentonite is composed of a high percentage of Montmorillonite. Different types of bentonites are classified 50 according to the cations present and their percentage. In industrial applications it has been shown that hectorite is in some cases superior to bentonite (primarily Montmorillonite) owing to its capacity for swelling and dispersibility. That has been attributed to its smaller particle size. [0011] In addition to natural smectite, there are other synthetic options such as Laponite (synthetic hectorite), fluoro- hectorites or fluoride Muscovites which can absorb water and swell in a manner similar to the smectites. There are clays 55 with sodium activation (calcium bentonite, to obtain sodium bentonites). [0012] The main limitation presented by waterproofing barriers that contain bentonite powder is that they conform waterproofing systems of different layers of geosynthetics in which it is necessary for the bentonite to be attached, supported and/or confined between the layers that make up the system, such as: geotextiles, geomembranes, geomesh- 2 EP 3 106 489 A1 es, or combinations thereof, in this way guaranteeing the cohesion of the bentonite powder and preventing its migration and/or dispersal during and after installation. [0013] On the other hand, super absorbent polymers (SAP), are polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass. Water-absorbent polymers, which are classified as hydrogels when they 5 reticulate, absorb aqueous solutions through hydrogen bonds with the water molecules. The capacity of a SAP to absorb water is a factor of the ionic concentration of the aqueous solution. [0014] SAPs with low density reticulation generally have a higher absorbent capacity and swell to a greater degree. These types of SAP also have a softer and stickier gel formation. Polymers with high density reticulation exhibit lower absorbent capacity and swell less, but the gel strength is firmer and the shape of the particles can be maintained, even 10 under moderate pressure. [0015] The main use for SAPs is found in disposable hygiene products, such as baby nappies, protective underwear for adults and sanitary pads. SAPs are also used to blocking water penetration into underground electric power or communications cables, horticultural water retention agents, spill and waste aqueous fluid control, and the production of artificial snow. 15 [0016] Acrylic polymers, or super absorbent polymers (SAP) in their dry state, resemble a curled coil (FIG. 2). When these molecules are placed in water, hydrogen bridge links are established with the surrounding HOH causing them to be uncurled and straightened (FIG. 3). [0017] When the molecules straighten, they increase the viscosity of the surrounding fluid. Super absorbent chemistry requires two things: The addition of small molecules that transversally join the polymer strands forming a mesh (reticu- 20 lation) and the partial neutralization of the carboxyl acid groups (-COOH) along the main polymer chain (-COO -Na+). [0018] The water molecules are attracted towards the mesh through a diffusion gradient which is formed by the neutralisation of sodium in the main polymer chain. The polymer chains attempt to straighten out, but are limited due to the reticulation. Thus, the particles expand as water passes to the mesh (FIG. 4). [0019] The water molecules are firmly affixed to the carboxylate ions of the super absorbent polymer mesh via hydrogen 25 bridge links. Many soluble metals also have a tendency towards ionic exchange with the sodium along the main polymer chain and are retained, which is why polyacrylates can be used as sequestrants or chelating agents in some detergents for use in hard water. The appearance of a super absorbent molecule appears in greater detail in FIG. 5, and, on a larger scale, the appearance of a super absorbent polymer mesh can be seen in detail in FIG.6. 30 Description
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