Flame-retardant breather membrane

Abstract

A flame-retardant film comprising a base sheet containing glass fibers having a basis weight of 296 to 420 grams per square meter and a maximum organic content of 1.5 weight percent, and a thermoplastic elastomer film attached to the base sheet, wherein the film is a thermoplastic elastomer film having a basis weight of 20 to 35 grams per square meter, the thermoplastic elastomer film being attached to the base sheet using an adhesive that is discontinuously present between the film and the sheet at an area density of 25 to 40% and in an amount of 4 to 6 grams per square meter, and the flame-retardant film having a total heat of combustion (PCS) of less than 3 MJ / kg and less than 4 MJ / sqm as measured according to EN ISO 1716.

Description

Technical Field

[0001] The present invention relates to a sheet structure suitable for use in buildings and construction, specifically, a sheet structure that is flame retardant, resistant to the passage of liquid water, allows the passage of water vapor, and is suitable for use as a facade product of a building. The sheet structure is particularly useful in buildings having an open facade using spacers, and the sheet structure may be exposed to the environment.

Background Art

[0002] In recent years, improved flame-retardant building cladding materials have attracted attention due to building fires that have drawn attention, such as the fire at the 24-story Grenfell Tower in west London. The fire started on a lower floor but rapidly spread across the outside of the building to all occupied floors, being accelerated by combustible cladding and external insulation that was dangerously flammable, and there were voids between them that created a chimney effect.

[0003] This type of structure may include exterior decorative cladding attached to the exterior sheath material of a building, and in some cases, the attachment may include spacers for attaching the cladding, with a void between the building's cladding and the exterior sheath material. In some cases, it is desirable to have a layer that is vapor permeable but water resistant between the cladding and the exterior sheath material to provide improved energy efficiency to the building. Typically, this vapor permeable but water resistant layer is attached to the surface of the exterior sheath material and is referred to as a "breather membrane" or a water resistant barrier (WRB).

[0004] The development of a sufficiently non-combustible breather membrane with high permanent water resistance and water vapor permeability has been difficult. The sheet structures currently used as breather membranes in these types of facade applications have significant negative properties.

[0005] One such sheet structure is a heavy three-layer structure of glass fiber with a surface covered by a microporous polymer layer and an outer surface of perforated aluminum, where the aluminum is perforated to achieve the desired breathability of the sheet structure. This sheet structure meets many of the requirements for breathability and water resistance, and even the requirements for Euroclass A2 fire class. However, the use of microporous membranes is undesirable because surfactants, which can lower the surface contact angle, can affect the water penetration prevention performance and allow water to penetrate through the micropores, meaning that the water penetration prevention performance is not permanent. Furthermore, the manufacture of the sheet structure requires combining, overlapping, and laminating three different types of layers, and the associated complexity and cost are undesirable.

[0006] Therefore, a two-layer sheet structure would be simpler and more desirable, but one such sheet structure is a layer of glass fiber with a surface continuously coated with extruded silicone, polyurethane, or acrylic polymer. However, this material has low permeability or limited ability to prevent water intrusion. Intuitively, the ability to reduce water intrusion can be improved by providing a thicker coating, but this would result in a further reduction in permeability or water vapor transfer or a defect in fire response due to an increase in the PCS value.

[0007] Therefore, the industry is facing increasing demands for higher fire safety requirements, and regulations are expected to become more stringent, creating a need for non-combustible, breathable, and watertight membranes for facade applications. Particularly needed are breather membranes with a two-layer structure and a desired combination of vapor permeability, liquid water resistance, and non-combustibility. In particular, there is a need for breather membranes that can meet the so-called "trinity" of properties at a high performance level, which is a combination of sufficient breathability (Sd value < 0.12 m), water resistance (W1 class), and non-combustibility (fire class A2). [Overview of the project] [Means for solving the problem]

[0008] The present invention relates to a flame-retardant film comprising a glass fiber-containing base sheet having a basis weight of 296 to 420 grams per square meter and a maximum organic content of 1.5 weight percent, and a thermoplastic elastomer film attached to the base sheet having a basis weight of 20 to 35 grams per square meter, wherein the thermoplastic elastomer film is attached to the base sheet using an adhesive, the adhesive is discontinuously present between the film and the sheet at an area density of 25 to 40%, the adhesive is present in an amount of 4 to 6 grams per square meter, and the flame-retardant film has a total heat of combustion (PCS) of less than 3 MJ / kg and less than 4 MJ / sqm as measured according to EN ISO 1716. [Modes for carrying out the invention]

[0009] The present invention relates to a flame-retardant breather membrane having a two-layer structure with a desired trinity of properties, wherein the breather membrane can be combined with flame-retardant tape to provide a lightweight, non-combustible shield in or on the facade of a building.

[0010] Heat generation is the amount of energy released by the complete combustion of a material. This amount of energy determines how much heat a particular material contributes to a fire. Simply put, the more heat, the faster the fire spreads. The heat content of a panel is indicated by its PCS (an abbreviation of the French term "Pouvoir Calorifique Superieur") value. A higher PCS value indicates a higher heat content in the panel, meaning the panel contributes more to the fire.

[0011] In the European Union, EN13501-1 specifies a fire safety classification system called the Euroclass system, with a range of classes from the most stringent A1 and A2 to B, C, D, E, and F. The class indicates the degree of non-combustibility; classes A1 and A2 are non-combustible, while classes B through F are combustible. When non-combustible materials are used, they contribute very little to fire, so they are basically designed without considering fire risk. The non-combustibility rating of A1 and A2 indicates that limits are set on the material's heat content (PCS value). These limits are not set for combustible materials (B through F). Non-combustible facade materials (Euroclass A1 and A2) have very low heat output and therefore contribute very little to fire, and Euroclass A1 has a lower PCS limit than Euroclass A2.

[0012] The breather membrane comprises a base sheet containing glass fibers and a thermoplastic elastomer film bonded to the base sheet with adhesive. Specifically, the breather membrane is a combination of a very thin layer of thermoplastic polyurethane (TPU) monolithic film laminated with a small amount of polyurethane adhesive that does not sacrifice vapor permeability to prevent liquid ingress, and a glass fiber fabric with a very low organic content. The breather membrane meets the requirements of Euroclass A2 fire protection rating.

[0013] The base sheet containing glass fibers is preferably a plain weave glass fabric, and in some embodiments, the base sheet contains E-glass. In some embodiments, the base sheet is a plain weave E / ECR (corrosion-resistant E-glass) glass mat with leno weft threads. It is considered that a base sheet containing ceramic or silica glass can be used, as long as the requirements for organic content are met.

[0014] The base sheet has a basis weight of 296 to 420 grams per square meter, and in some embodiments, a basis weight of 360 to 385 grams per square meter. In some embodiments, the base sheet has a basis weight of 360 to 370 grams per square meter.

[0015] The base sheet has a maximum organic content of 1.5 weight percent, where the percentage of organic content is based solely on the weight of the base sheet. In some preferred embodiments, the base sheet has a maximum organic content of 1.0 weight percent, where the percentage of organic content is again based solely on the weight of the base sheet (i.e., the total weight of the organic material and glass). In some embodiments, the base sheet has a total heat of combustion (PCS) of less than 0.38 MJ / kg as measured according to EN ISO 1716. In some other embodiments, the base sheet has a total heat of combustion (PCS) of less than 0.25 MJ / kg as measured according to EN ISO 1716. Base sheets with low organic content can be produced by controlling the amount of organic material used in the manufacture of the base sheet (such as the amount of binder and / or fiber finishing agent), or by eliminating or removing organic matter from the base sheet after manufacture by chemical or thermal processes, or by some combination of both techniques.

[0016] The flame-retardant film includes a layer of thermoplastic elastomer film bonded to a base sheet. The layer of thermoplastic elastomer film provides the sheet with the desired waterproofing while also providing sufficient moisture permeability. Specifically, the film is preferably a monolithic film layer, and the thermoplastic elastomer is a hydrophilic material. Thus, the monolithic thermoplastic elastomer film layer is hydrophilic, meaning that a considerable amount of water vapor can be transferred through the film by absorbing water on one side of the film where the water concentration is high and desorbing or evaporating water on the other side where the water concentration is low. Hydrophilicity is defined as having a contact angle in the range of 0 to 90 degrees, as determined by ASTM D5946. "Monolithic" means that the film is not a microporous film and does not have continuous pores in the thickness direction. Thermoplastic elastomers are designated into six general classes by ISO 18064:2022. Three of these classes can be sufficiently hydrophilic to function as a moisture-permeable layer. These classes include thermoplastic polyurethane (TPU), thermoplastic copolyester (TPE-E), and thermoplastic polyamide (TPE-A).

[0017] The thermoplastic elastomer film attached to the base sheet has a basis weight of 20 to 35 grams per square meter. In some embodiments, the thermoplastic elastomer film has a basis weight of 25 to 31 grams per square meter. In some embodiments, the thermoplastic elastomer film has a thickness of 18 to 31 micrometers. In some preferred embodiments, the thermoplastic elastomer film has a thickness of 22 to 28 micrometers.

[0018] In some embodiments, the thermoplastic elastomer film may include a TPC-E elastomer; the TPC-E elastomer contains hard crystalline polyester blocks and long-chain soft amorphous polyether blocks. An example of a TPC-E material is a product sold under the brand name Hytrel®. In some embodiments, the thermoplastic elastomer film may include a TPE-A elastomer; the TPE-A elastomer contains polyether soft amorphous blocks and polyamide hard blocks. An example of a TPE-A material is a product sold under the brand names PEBAX® and VESTAMID®.

[0019] In some embodiments, the thermoplastic elastomer film is a TPU elastomer. The TPU elastomer utilizes a diisocyanate reacted with a polyester diol or polyether diol and includes an aromatic polyurethane polymer based on a linear segmented block copolymer composed of hard and soft segments. Examples of TPU materials include products marketed under the brand names Platilon®, Pellethane®, and Estane®. A preferred embodiment of TPU is Platilon® U.

[0020] Microporous films have been found to be less desirable for providing permanent waterproofing to base sheets in breather membranes. Microporous films refer to extruded or cast films or coatings that have pores made large enough to block liquid water droplets while allowing vapor molecules to pass through, and whose surface energy can be altered to reduce their ability to penetrate. These microporous films are less desirable for use as facade materials because any surfactant used in cleaning the exterior surfaces of buildings can alter the surface energy of the microporous films, allowing penetration and thus failing to provide the desired level of durable waterproofing.

[0021] A thermoplastic elastomer film is bonded to a base sheet by an adhesive. The adhesive is discontinuous between the base sheet and the film; that is, the adhesive does not continuously coat the surface of either the base sheet or the film, and does not form a continuous layer between the base sheet and the film. The absence of a continuous adhesive layer allows the breather film to "breathe," allowing water vapor to pass through the adhesive bonds of the breather film. The adhesive can be discontinuously applied to one or both of the base sheet and / or film layers using a suitable technique such as direct gravure printing, which provides individual domains of the adhesive to the surface of the base sheet and / or film. These domains form bonds or joints between the base sheet and the film. The discontinuous adhesive can be applied in any desired pattern, e.g., lines, dots, polygons, or other forms. Several suitable methods for applying adhesive in a discontinuous pattern to bond sheet materials are described, for example, all in Wyner et al.'s U.S. Patent Nos. 5,874,140; 5,531,419; 7,55,377; and U.S. Patent Application Publication No. 20050130521.

[0022] Just as microporous films were found unsuitable for use in breather membranes, films directly extruded onto the surface of a base sheet were also found unsuitable for breather membranes. Such directly extruded films have the drawback of pinholes, which affect their water-impermeable performance. These pinholes are thought to be due to the surface characteristics of the base sheet containing glass fibers, which may have glass filaments protruding randomly from the sheet, and these glass filaments can inevitably penetrate very thin extruded films. Therefore, since the surface of the monolithic film layer is discontinuously bonded to the surface of the base sheet, unlike directly extruded films, discontinuous bonding of the monolithic film to the base sheet was found to tend to mitigate any problems associated with the roughness of the base sheet surface.

[0023] The adhesive is discontinuously present between the film and the sheet at an area density of 25-40%, and the adhesive is present in an amount of 4-6 grams per square meter. In some embodiments, the adhesive is discontinuously present between the film and the sheet at an area density of 30-35%. In a preferred embodiment, the adhesive is discontinuously present between the film and the base sheet as a uniformly applied adhesive domain or circular dots. In some embodiments, the adhesive is polyurethane. Alternative adhesives may include epoxy resins and hot melts.

[0024] In a preferred embodiment, the flame-retardant film consists of two layers. As used herein, the term "layer" refers to separate regions of independent materials in the form of a film or other sheet material. Thus, the arrangement of the adhesive between the layers is not considered a layer herein.

[0025] The two-layer flame-retardant film adhered with an adhesive has a total heat of combustion (PCS) of less than 3 MJ / kg and less than 4 MJ / sqm as measured according to EN ISO 1716, and preferably has a Euroclass A2 fire protection rating according to EN 13501-1.

[0026] In some embodiments, the flame-retardant film has an equivalent air layer thickness (Sd value) for water vapor diffusion of less than 0.12 meters as measured by EN ISO 12572. In some other embodiments, the flame-retardant film has an equivalent air layer thickness (Sd value) for water vapor diffusion of less than 0.1 meter as measured by EN ISO 12572. The Sd value is a measure of how resistant the film is to moisture diffusion, expressed as an equivalent air layer thickness. The unit of measurement is meters.

[0027] In some embodiments, the flame-retardant film shows no evidence of water penetration after being exposed to a 200 mm water column for 2 hours according to EN 1928 (Method A). This is equivalent to a water tight classification of Class W1, which requires zero water leakage at 200 mm according to the test method.

[0028] In some embodiments, the flame-retardant film after UV aging at 50°C for at least 5000 hours corresponding to 800 MJ / m2 according to EN 1297 shows no evidence of water penetration after being exposed to a water column of 200 mm for 2 hours according to EN 1928 (Method A). Again, this is equivalent to a watertight classification of Class W1.

[0029] The flame-retardant film is useful as a material layer in a facade or wall system, particularly in the material layer near or on the outer surface of the wall, preferably in the material layer between the outer cladding and the wall support structure of the wall. Preferably, the material layer of the flame-retardant film consists of individual layers of the flame-retardant film that cover the wall and further overlap at the edges. This type of arrangement of the individual layers of the flame-retardant film is considered in this specification as multiple "laminated sections" of the flame-retardant film. Preferably, the edge of the first laminated section of the flame-retardant film overlaps the second laminated section of the flame-retardant film by at least 100 mm.

[0030] In some embodiments, the laminated sections of the flame-retardant film are further sealed with a flame-retardant tape, and in some embodiments, the tape has a total combustion heat (PCS) of less than 7.4 MJ / kg and less than 1.6 MJ / sqm as measured according to EN ISO 1716. Further, in some embodiments, the total surface coating area of the tape on the facade or wall system is 5.4% or less based on the coating area on the wall structure of the material layer including the flame-retardant film.

[0031] In some embodiments, the facade or wall system has an outer surface and an inner surface, and the facade or wall system may further include a plurality of layered sections of vapor barrier film located closer to the inner surface of the wall structure than the layered sections of the flame-retardant film. This vapor barrier film can also be sealed with tape. In a preferred embodiment, the edges of the first layered sections of the vapor barrier film overlap the second layered sections of the vapor barrier film by at least 100 mm. In some embodiments, the vapor barrier film has a total heat of combustion (PCS) of less than 0.51 MJ / kg and less than 0.1 MJ / sqm. In some embodiments, the total surface coverage area of ​​the tape on the vapor barrier film is 5.4 percent or less.

[0032] Test method EN ISO 1716:2018 is a combustion heat test that determines the potential maximum total heat output of a product when completely burned, regardless of its end use. This test also applies to classes A1 and A2 and their subclasses. This test is used to determine both total heat of combustion (PCS) and true heat of combustion (PCI).

[0033] EN ISO 13823:2020 is a fire reaction test for building products, in which building products excluding flooring are exposed to a thermal attack by a single combustible material. This European standard specifies a test method for determining the fire reaction performance of building products excluding flooring when exposed to a thermal attack by a single combustible material (SBI).

[0034] The thickness of the thermoplastic elastomer film was determined according to ASTM D6988-21. [Examples]

[0035] A flame-retardant and weather-resistant barrier laminate was produced as follows: The base sheet was an E / ECR (corrosion-resistant E-glass) mat, a plain weave fabric with leno weft yarns, a basis weight of approximately 362 gsm, and an organic content of 1.0 wt percent (ash / glass content 99.0 wt percent) as determined by TGA according to ASTM E1131-20. The base sheet further had a total heat of combustion (PCS) value of 0.234 MJ / kg according to EN ISO 1716. A thermoplastic polyurethane (TPU) film (Platilon® U) with a basis weight of 28 gsm was then bonded to the glass mat using a polyurethane (PU) adhesive applied using a discontinuous point bonding method. Specifically, the PU adhesive was a one-component reactive hot-melt adhesive, applied in an amount of approximately 5 gsm as discontinuous domains in a uniformly applied dot pattern, resulting in an adhesive coverage area density of 35% on the base sheet, leaving approximately 65% ​​of the area between the base sheet and the film unbonded. The film was bonded or laminated to the base sheet using a set of nip rolls after the adhesive was applied, and then the adhesive was cured. The final flame-retardant and weather-resistant barrier laminate had a width of 1.5 m, a basis weight of 395 g, and a total heat of combustion (PCS) value of 2.839 MJ / kg and 1.127 MJ / sqm according to EN ISO 1716. Table 1 shows the tests performed on the laminate and the results obtained thereafter. Any version of any standard or method referred to herein shall be the most recent version approved as of the date of this application, unless otherwise specified herein.

[0036] [Table 1]

Claims

1. A flame-retardant film, wherein the flame retardant is A base sheet containing glass fibers, The base sheet has a basis weight of 296 to 420 grams per square meter. The base sheet has a maximum organic content of 1.5 weight percent. Base sheet and A thermoplastic elastomer film attached to the base sheet, The film has a basis weight of 20 to 35 grams per square meter. Thermoplastic elastomer film and Includes, The thermoplastic elastomer film is attached to the base sheet using an adhesive, the adhesive is discontinuously present between the film and the sheet at an area density of 25-40%, and the amount of the adhesive is 4-6 grams per square meter, and The flame-retardant film is a flame-retardant film having a total heat of combustion (PCS) of less than 3 MJ / kg and less than 4 MJ / sqm, as measured in accordance with EN ISO 1716.

2. The base sheet has a basis weight of 360 to 385 grams per square meter, as described in claim 1.

3. The base sheet has a total heat of combustion (PCS) of less than 0.38 MJ / kg as measured in accordance with EN ISO 1716, the flame-retardant film according to claim 1 or 2.

4. The flame-retardant film according to any one of claims 1 to 3, wherein the base sheet is a plain weave glass fabric.

5. The base sheet is a flame-retardant film according to any one of claims 1 to 4, comprising E-glass.

6. The flame-retardant film according to any one of claims 1 to 5, wherein the thermoplastic elastomer film has a basis weight of 25 to 31 grams per square meter.

7. The flame-retardant film according to any one of claims 1 to 6, wherein the thermoplastic elastomer film comprises thermoplastic polyurethane (TPU), thermoplastic copolyester (TPE-E), thermoplastic polyamide (TPE-A), or a mixture thereof.

8. The flame-retardant film according to claim 7, wherein the thermoplastic elastomer film comprises an aromatic polyurethane polymer based on a polyester diol or a polyether diol.

9. The flame-retardant film according to any one of claims 1 to 8, wherein the thermoplastic elastomer film is a monolithic film.

10. The flame-retardant film according to any one of claims 1 to 9, wherein the adhesive is discontinuously present between the film and the sheet and has an area density of 30 to 35%.

11. The flame-retardant film according to any one of claims 1 to 10, wherein the adhesive exists discontinuously as adhesive dots.

12. The flame-retardant film according to any one of claims 1 to 11, wherein the adhesive is polyurethane.

13. A flame-retardant film according to any one of claims 1 to 12, having an equivalent air thickness (Sd value) of less than 0.12 for water vapor diffusion, as measured in accordance with EN ISO 12572.

14. The flame-retardant film according to any one of claims 1 to 13, wherein the flame-retardant film shows no evidence of water penetration after exposure to a 200 mm water column for 2 hours according to EN 1928 (Method A).

15. 800 MJ / m according to EN 1297 2 The flame-retardant film according to any one of claims 1 to 13, wherein the flame-retardant film, after UV aging at 50°C for at least 5000 hours, shows no evidence of water penetration after exposure to a 200 mm water column for 2 hours according to EN 1928 (Method A).

16. A flame-retardant film according to any one of claims 1 to 15, having a Euroclass A2 fire resistance rating in accordance with EN 13501-1.

17. A facade or wall system comprising a plurality of layered compartments of a flame-retardant film according to any one of claims 1 to 16, sealed with tape having a total heat of combustion (PCS) of less than 7.4 MJ / kg and less than 1.6 MJ / sqm as measured in accordance with EN ISO 1716, The edge of the first layered section of the flame-retardant film overlaps with the second layered section of the flame-retardant film by at least 100 mm. A facade or wall system in which the total surface coverage area of ​​the tape on the facade or wall system is 5.4 percent or less.

18. The vapor barrier film further includes a plurality of layered compartments that are further sealed with tape, the edge of the first layered compartment of the vapor barrier film overlaps with the second layered compartment of the vapor barrier film by at least 100 mm, The facade or wall system has an outer surface and an inner surface, The facade or wall system according to claim 17, wherein the layered compartments of the vapor barrier film are located closer to the inner surface than the layered compartments of the flame-retardant film.

19. The vapor barrier film has a total heat of combustion (PCS) of less than 0.51 MJ / kg and less than 0.1 MJ / sqm. The facade or wall system according to claim 18, wherein the total surface coverage area of ​​the tape on the vapor barrier film is 5.4 percent or less.

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