Bituminous membranes with reflective outer coating

Abstract

The present invention relates to a bituminous sealing membrane (1) comprising - a bituminous layer (2) and - a surface finish (3) in contact with the bituminous layer (2), the surface finish comprising a fibrous structure (4) comprising a non-woven cloth (5) made of glass fibres and / or polyester fibres, the lower face (5b) of which is in contact with the bituminous layer (2) and, on the upper surface (5a) of the non-woven cloth (5) that is not in contact with the bituminous layer (2), a white coating (7) comprising from 0.3 to 6% by weight of TiO2 particles, from 70 to 90% by weight of one or more white mineral loads and from 8 to 25% by weight of an organic polymer free of carbon-carbon double bonds, said percentages being expressed as dry weight relative to the total dry weight of the white coating, characterised in that the fibrous structure (4) of the surface finish (3) further comprises reinforcement fibres (8) and in that the bituminous sealing membrane (1), and notably the bituminous layer (2), is free of other fibrous structures.

Description

[0001] Description

[0002] Title: Bituminous membranes with reflective exterior coating

[0003] The present invention relates to a white bituminous waterproofing membrane for roofs, comprising a unique fibrous structure reinforced by continuous fibers.

[0004] Combined with population growth and urban densification, climate change will make the phenomenon of urban heat islands (UHIs) more prevalent, i.e., an increase in air and surface temperatures in city centers compared to outskirts and rural areas, particularly at night. The progression of this phenomenon will lead to an increase in the costs of air conditioning buildings.

[0005] The formation of urban heat islands is due to the significant absorption of solar radiation by the materials constituting the surfaces of cities such as concrete, cement, asphalt, bitumen, metals etc. The energy absorbed during the day is transmitted by conduction throughout the volume of materials and is emitted in the form of thermal radiation (IR) during the night.

[0006] For many years, research has been undertaken to significantly reduce the absorption of solar radiation by urban surfaces, particularly building roofs, by increasing the reflective properties of these surfaces.

[0007] As part of these developments, three parameters were defined in order to compare the behavior of different materials with respect to solar radiation:

[0008] Solar reflectivity or reflectance (SR) expresses the ability of a surface to reflect solar radiation. It is the ratio of solar energy reflected by the surface of a material to the incident energy. SR is therefore equal to 0 when the radiation energy is totally absorbed and equal to 1 when the surface reflects all of the solar radiation. SR is determined in accordance with EN410 (2011).

[0009] Thermal emissivity (EI) characterizes the ability of a surface to re-emit absorbed energy in the form of thermal radiation in the infrared. EI can be calculated by following the EN 12898 standard. Finally, the ASTM E1980 standard defines a solar reflective index (SRI) calculated from the two parameters SR and EI above using the formula [math 1 ]

[0010] SRI = 123.97 — 141.35 9,655 days 2 with [math 2] where a is the solar absorbance (1 - solar reflectance), s the thermal emissivity and h c a convection coefficient whose value depends on the wind strength.

[0011] Cool roofs are particularly widespread in the United States of America, where the CRRC (Cool Roof Rating Council) was created to develop methods for determining SR and IE parameters for the various roofing materials available on the market and to promote knowledge in the field of low solar absorbance roofs.

[0012] A federal certification called EnergyStar, which sets requirements for cool roofs, was created by the U.S. Environmental Protection Agency (EPA). Some states, such as California, have created their own certification (California Title 24).

[0013] SRI requirements are generally more stringent for low-slope roofs (less than 2°) than for steep-slope roofs, visible from the street, for which local laws often impose colors. California Title 24 certification thus requires low-slope roofs, after accelerated aging, to have a solar reflectance (SR) of at least 0.63, a thermal emissivity (EI) of at least 0.75 and a solar reflectance index of at least 75.

[0014] The purpose of the present application is to propose bituminous membranes capable of establishing the waterproofing of low-slope roofs and which, thanks to a white-colored surfacing laminated on one side of the bituminous membrane, have low solar absorption properties (cool roof) and meet the requirements of EnergyStar® or even California Title 24 certifications for low-slope roofs. Bituminous membranes of this type have already been described in patent EP1618245B1. They are prepared by applying a white-colored coating composition, containing an organic polymer and mineral fillers and white pigments, to a fibrous structure, also called a fiber web. After drying the white organo-mineral coating, a bituminous membrane is applied to the other side of the fibrous structure. The method for applying the bituminous membrane is described in patent EP 0 876 532B1.In this process, a first layer of fibers is coated with the surface coating and the coating is dried. Then a bituminous mass is applied to the other side of this first layer of fibers coated with the dry coating, then the deposited bituminous layer is covered with a second layer of fibers, then with a second bituminous layer (Figure 1 of EPO 876 532 B1). The waterproofing membranes obtained thus contain two layers of fibers, which are respectively a non-woven mat of glass fibers and a non-woven mat of polyester fibers, the polyester fibers being particularly well suited to contact with the bituminous layer. The non-woven mat of glass fibers guarantees the dimensional stability of the structure during manufacture, in particular at the time of depositing the bituminous mass on the fibrous structure subjected to tension and also at the time of application of the waterproofing membrane on the roof (heat supply).The non-woven mat made of polyester fibers prevents, thanks to its elasticity, the appearance of cracks over time, cracks which could lead to a lack of waterproofing of the roof.

[0015] The present invention is based on the discovery that it is possible to prepare white bituminous membranes of this type using a single fibrous structure based on a non-woven fabric made of glass fibers and / or polyester fibers, i.e. omitting the polyester non-woven mat present in the bituminous layer of the membranes of the prior art.

[0016] In order for the final white bituminous membrane to have satisfactory dimensional stability when hot and to resist cracking and splitting over time, it is necessary to reinforce the non-woven mat with reinforcing fibers, preferably textile glass reinforcing fibers. These reinforcing fibers, incorporated into the non-woven mat, thus make it possible to dispense with a second fibrous structure in the bituminous layer of the membrane of the present invention, which simplifies the manufacturing process and reduces manufacturing costs.

[0017] The present application relates to a bituminous waterproofing membrane comprising

[0018] - a bituminous layer and

[0019] - surfacing in contact with the bituminous layer, the surfacing comprising

[0020] • a fibrous structure comprising a non-woven mat of glass fibers and / or polyester fibers, the lower face of which is in contact with the bituminous layer, and

[0021] • on the upper face of the non-woven mat which is not in contact with the bituminous layer, a white coating comprising from 0.3 to 6% by weight of TiO2 particles, from 70 to 90% by weight of one or more white mineral fillers, and from 8 to 25% by weight of an organic polymer free of carbon-carbon double bonds, these percentages being expressed in dry weight relative to the total dry weight of the white coating, said membrane being characterized by the fact that the fibrous structure of the surfacing further comprises reinforcing textile glass fibers and by the fact that the waterproofing bituminous membrane, and in particular the bituminous layer, is free of other fibrous structures.

[0022] The nonwoven mat of the fibrous structure may consist of glass fibers or polyester fibers or a mixture of glass fibers and polyester fibers. The fibers of the nonwoven mat are preferably polyester fibers, optionally mixed with glass fibers. In the case of a mixture, at least 50% by weight, preferably at least 70% by weight of the fibers of the nonwoven mat are polyester fibers.

[0023] The use of polyester fibers in the non-woven mat improves the resistance to static punching (NF EN 12730) of the bituminous membrane.

[0024] The glass fibers and polyester fibers of the nonwoven mat are preferably short fibers having lengths between 2 and 100 mm, preferably between 6 and 80 mm. The glass fibers and / or polyester fibers forming the nonwoven mat are held together by means of an organic binder, preferably a thermoset organic binder based on phenol-formaldehyde, urea-formaldehyde or melamine-formaldehyde resin or based on bio-sourced polyester resins prepared from bio-sourced carbohydrates and polyacids. The binder may also be a binder based on a styrene-butadiene rubber (SBR) latex.

[0025] As explained in the introduction, the unique fibrous structure of the bituminous membrane of the present invention comprises, in addition to the non-woven mat of glass and / or polyester fibers, reinforcing fibers. The reinforcing fibers are continuous fibers, i.e. of infinite length. They are continuous fibers of textile glass, i.e. obtained by mechanical drawing according to known methods, or continuous fibers of polyester.

[0026] When the continuous fibers are glass fibers, they are made up of individual filaments, gathered into "basic yarns" (also called "silion" or "roving"). Each basic yarn generally contains from 50 to 2000, preferably from 100 to 1600, and in particular from 150 to 500 individual filaments.

[0027] The individual filaments advantageously have a diameter of between 5 and 20 pm, preferably between 6 and 16 pm.

[0028] The linear mass of the base yarns is typically between 20 and 400 tex, preferably between 50 and 250 tex.

[0029] The glass reinforcing fibers preferably have an orientation parallel to the length of the fiber structure strip and therefore parallel to the length of the bituminous membrane.

[0030] When the continuous fibers are polyester, they are made up of individual filaments, gathered into "basic yarns" (also called "silion" or "wick"). Each basic yarn generally contains from 50 to 2000, preferably from 100 to 1600, and in particular from 180 to 450 individual filaments.

[0031] The individual filaments advantageously have a diameter of between 5 and 40 pm, preferably between 6 and 30 pm.

[0032] The linear density of the base yarns is typically between 20 and 400 tex, preferably between 50 and 250 tex. The polyester reinforcing fibers advantageously have an orientation parallel to the length of the strip of the fibrous structure and therefore parallel to the length of the bituminous membrane but can also be oriented at a fairly large angle (typically greater than 70°) relative to the length of the bituminous membrane.

[0033] The unique fiber structure of the membrane, whether made of glass fibers or polyester fibers, preferably has a sandwich structure with a layer of reinforcing fibers located between two layers of short fibers assembled into a non-woven mat.

[0034] The reinforcing fibers are preferably glass fibers.

[0035] The fibrous structure comprising the nonwoven mat and the reinforcing fibers advantageously has a surface mass of between 30 and 500 g / m 2 , preferably between 50 and 350 g / m 2 .

[0036] When the nonwoven mat comprises both textile glass fibers and polyester fibers, the weight ratio of glass fibers to polyester fibers is between 0.05 and 1.5, preferably between 0.1 and 1.

[0037] The manufacture of the bituminous membranes of the present invention comprises a first step of manufacturing a white surfacing, consisting of the fibrous structure (reinforced non-woven mat) and the white coating. An aqueous coating composition, containing the organic polymer, the white mineral fillers and the TiO2 particles is applied to the fibrous structure.

[0038] The coating composition can be prepared by mixing 10 to 30% by weight of water, 50 to 65% by weight of white mineral fillers, 10 to 30% by weight of organic polymer latex free from carbon-carbon double bonds and 0.2 to 5% of ÜO2 particles, these percentages being expressed relative to the total weight of the aqueous coating composition.

[0039] The coating composition may also include other additives such as a dispersing agent to ensure good dispersion of pigments and mineral fillers. This product is generally a solution containing a high molar mass copolymer with good affinity for the pigment. It is also possible to add a thickener to the coating composition to adjust the viscosity of the composition. This rheology modifier is often organic and may be cellulosic or synthetic (associative or non-associative).

[0040] Finally, other additives can be introduced into the composition such as biocidal products, compounds limiting the appearance of foam, flame retardants, an aqueous wax emulsion providing a hydrophobic character to the fibrous structure, or additives increasing the resistance to UV rays of the surface (UV absorber or photostabilizing compounds).

[0041] The white mineral fillers are preferably selected from the group consisting of CaCOs, wollastonite, silica, kaolin, talc, barium sulfate, bentonite, zirconia, mica and quartz. These mineral fillers preferably have median sizes between 1 pm and 100 pm.

[0042] The TiO2 particles advantageously have a median size (D50) in volume, determined by laser granulometry, between 200 and 800 nm.

[0043] The organic polymer free of carbon-carbon double bonds is preferably selected from the group consisting of acrylic polymers, aliphatic polyurethanes, fluorinated or chlorinated polymers, and poly(vinyl butyral). Aqueous dispersions of such polymers are available, for example, under the trade names AC2025 and AC2077 (Alberdingk), Pilotée® LEB20 (Omnova Solutions), Orgal® P838W and Orgal® P850RR (Monokem Kimya), Primai® AC (Dow), for acrylic polymers; U400N (Alberdingk), for aliphatic polyurethanes; Kynar Aquatec® (Arkema) for fluorinated or chlorinated polymers; Shark Dispersion® MW2, WX2 or FX2 (Shark Solutions) for poly(vinyl butyral) dispersions. The absence of carbon-carbon double bonds is interesting from the point of view of the longevity of the membrane's reflectivity.

[0044] The reflective properties of the dried white coating depend on the respective proportions of the mineral particles (ÜO2 & white fillers), on the one hand, and the organic polymer, on the other hand. Increasing the organic polymer fraction limits the final porosity of the white coating, which improves the reflectivity of the surface and prolongs the longevity of the coating. However, TiO2 and white fillers have a significant reflective power and must therefore be present in a sufficient quantity. The Applicant has found that the reflective properties are optimal when the weight ratio of all the mineral particles (i.e., ÜO2 and mineral fillers) to the organic polymer is between 1.5 and 2.5, preferably between 1.6 and 2.4 and ideally between 1.8 and 2.2.

[0045] The coating composition is applied to the fibrous structure, for example by knife coating. This application is carried out so that the other side of the fibrous structure remains free to receive the bituminous layer.

[0046] After applying the coating composition, the structure is dried, for example for 0.5 to 5 minutes at a temperature between 100 and 200 °C.

[0047] The dried surfacing thus obtained (comprising the fibrous structure and the white coating) has a surface mass of between 200 and 800 g / m 2 , preferably between 250 and 750 g / m 2 , especially between 300 and 700 g / m 2 It can be rolled up, stored and / or transported in order to be subsequently coated with the bituminous layer.

[0048] Thanks to the presence of continuous textile glass fibers incorporated in the non-woven mat, the surfacing will have excellent dimensional stability and will not deform during the application stage of the hot bituminous mass, even when the fibers of the non-woven mat are mainly polyester fibers.

[0049] The bituminous waterproofing membrane of the present invention has a surface mass of between 3 and 5.5 kg / m 2 .

[0050] The invention is illustrated with the aid of Figure 1 which represents a cross-section of a bituminous membrane according to the invention.

[0051] This bituminous membrane 1 comprises a fibrous structure 4 formed by a non-woven mat 5 having an upper face 5a and a lower face 5b and continuous reinforcing glass fibers 8 arranged parallel to each other at the core of the non-woven mat 5. The reinforcing fibers 8 are base yarns consisting of a plurality of individual filaments. The upper face 5a of the fibrous structure 4 is in contact with a white coating 7 formed of mineral particles (TiO2 and white mineral fillers, not shown) bound by an organic polymer. The lower face 5b of the fibrous structure 4 is in contact with a bituminous layer 2. The bituminous layer does not contain a fibrous structure.

Claims

DEMANDS 1. Bituminous waterproofing membrane (1) comprising - a bituminous layer (2) and - a surface treatment (3) in contact with the bituminous layer (2), the surface treatment comprising • a fibrous structure (4) comprising a non-woven mat (5) made of glass fibers and / or polyester fibers, the underside of which (5b) is in contact with the bituminous layer (2), and • on the upper face (5a) of the non-woven mat (5) which is not in contact with the bituminous layer (2), a white coating (7) comprising from 0.3 to 6% by weight of TiO2 particles, from 70 to 90% by weight of one or more white colored mineral fillers, and from 8 to 25% by weight of an organic polymer free of carbon-carbon double bonds, these percentages being expressed in dry weight relative to the total dry weight of the white coating, characterized by the fact that the fibrous structure (4) of the surfacing (3) further comprises reinforcing fibers (8) and by the fact that the bituminous waterproofing membrane (1), and in particular the bituminous layer (2), is free of other fibrous structures.

2. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that the reinforcing fibers are textile glass reinforcing fibers.

3. Bituminous waterproofing membrane according to claim 2, characterized in that the reinforcing textile glass fibers are made up of individual filaments, assembled by "base yarns", each base yarn containing from 50 to 2000, preferably from 100 to 1600, and in particular from 150 to 500 individual filaments.

4. Bituminous waterproofing membrane according to claim 2 or 3, characterized in that the individual filaments have a diameter between 5 and 20 pm, preferably between 6 and 16 pm.

5. Bituminous waterproofing membrane according to claim 1, characterized in that the reinforcing fibers are polyester fibers.

6. Bituminous waterproofing membrane according to claim 5, characterized in that the polyester reinforcing fibers are made up of individual filaments, assembled by "base yarns", each base yarn containing from 50 to 2000, preferably from 100 to 1600, and in particular from 180 to 450 individual filaments.

7. Bituminous waterproofing membrane according to claim 5 or 6, characterized in that the individual filaments have a diameter between 5 and 40 pm, preferably between 6 and 30 pm.

8. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that it has a sandwich structure with a layer of reinforcing fibers situated between two layers of short fibers assembled into a non-woven mat.

9. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that the fibrous structure (4) comprising the non-woven mat (5) and the continuous reinforcing fibers (8) has a surface mass of between 30 and 500 g / m² 2 preferably between 50 and 350 g / m 2 .

10. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that the surface (3) comprising the fibrous structure (4) and the white coating (7) has a surface mass of between 200 and 800 g / m² 2 , preferably between 250 and 750 g / m 2 , in particular between 300 and 700 g / m 2 . 1 1. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that the organic polymer is selected from the group consisting of acrylic polymers, aliphatic polyurethanes, and fluorinated or chlorinated polymers.

12. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that the white mineral fillers are selected from the group consisting of CaCOs, wollastonite, silica, kaolin, talc, barium sulfate, bentonite, zirconia, mica and quartz.

13. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that it has a surface mass of between 3 and 5.5 kg / m² 2 .

14. Bituminous waterproofing membrane according to any one of the preceding claims, characterized in that the TiU2 particles have a median size (D50) by volume, determined by laser particle size analysis, of between 200 and 800 nm.

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