This relates to a mesh coated with intumescent material, and in particular, a non-metal, woven mesh.
Intumescent materials are a class of substances that expand when exposed to high heat temperatures and direct flame. The expanded layer has a great ability to insulate and generally has low thermal conductivity. Intumescent coatings are often used and applied in passive fire resistance measures in buildings, construction, railroads, utility power poles, and other applications. U.S. pregrant pub. no. 2018/0038098 (Wall et al.) entitled “Intumescent Mesh” describes a flexible metal mesh with an intumescent coating.
According to an aspect, there is provided an intumescent mesh, comprising a mesh structure woven from strands, the strands defining openings in the mesh structure, the strands being non-metal; an intumescent material applied to the strands, the intumescent material being carried such that, in an inactivated state the intumescent material permits airflow through the openings in the mesh structure, and in an activated state the intumescent material swells and restricts airflow through the openings in the mesh structure; wherein the intumescent mesh is able to withstand a temperature of at least 980° C. for at least 10 minutes prior to failure.
According to other aspects, the intumescent mesh may comprise one or more of the following aspects, alone or in combination: the openings may be between about 0.18 inches and about 0.32 inches along a width and height; the openings may have an average size of about 0.25 inches +/−0.06 inches; the strands may be fibreglass strands; the mesh structure may be woven in a half Leno weave; the intumescent material may be activated at a temperature of at least 270° C.; the intumescent mesh may be able to withstand the temperature of at least 980° C. for at least 15 minutes prior to failure and failure may comprise a surface underlying the intumescent mesh, relative to a source of heat, reaching a temperature of about 150° C.; the intumescent mesh may be able to withstand temperature surges of up to 1250° C. for at least 1 minute without failure; the intumescent material and strands may be sized such that an available airflow area of the openings is about 25-75% of the mesh structure; the mesh structure with the intumescent material applied may be flexible; the mesh structure with the intumescent material may be applied is foldable; and the intumescent mesh may further comprise a surface coating applied between the mesh structure and the intumescent material, the surface coating being selected to improve adhesion between the mesh structure and the intumescent material.
According to an aspect, there is provided a method of protecting a surface against fire or heat, comprising the steps of: providing an intumescent mesh comprising an intumescent material applied to a mesh structure, the mesh structure being woven from non-metal strands that define openings in the mesh structure, the intumescent material being carried such that, in an inactivated state the intumescent material permits airflow through the openings in the mesh structure, and in an activated state the intumescent material swells and restricts airflow through the openings in the mesh structure, the intumescent material being activated upon application of an activation temperature, the intumescent mesh is able to withstand a temperature of at least 980° C. for at least 10 minutes prior to failure; and installing the intumescent material immediately adjacent to the surface to be protected.
According to other aspects, the method may further comprise the following aspects, alone or in combination: the intumescent material may be installed such that, when activated, the intumescent material is in contact with the surface to be protected; the mesh structure may be treated with a surface coating selected to improve an adhesion between the mesh structure and the intumescent material; the openings may be between about 0.18 inches and about 0.32 inches along a width and height; the openings may be about 0.25+/−0.06 inches; the strands may be woven using a half-Leno weave; the intumescent material may be activated at a temperature of at least 270° C.; the intumescent mesh may be able to withstand the temperature of at least 980° C. for at least 15 minutes prior to failure; failure may comprise the surface to be protected reaching a temperature of about 150° C.; the intumescent mesh may be able to withstand temperature surges of up to 1250° C. for at least 1 minute without failure; the intumescent material and strands may be sized such that an available airflow area of the openings is about 25-75% of the mesh structure; the intumescent mesh may be flexible; the intumescent mesh may be foldable; the method may further comprise a surface coating applied between the mesh structure and the intumescent material, the surface coating being selected to improve an adhesion between the mesh structure and the intumescent material.
These and other features will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to be in any way limiting, wherein:
An intumescent mesh, generally identified by reference numeral 10, will now be described with reference to
Referring to
Weaving mesh structure 12 enhances its strength and durability. While different weave patterns may be used, in one example, adequate results were achieved using a modified weave pattern, such as a modified Leno weave pattern that may be described as half-Leno, depicted in
It will be understood that the height and width of the openings may vary depending on various factors, such as the type of weave used, the equipment used to implement the weave pattern, the type of fibreglass used, or the preferences of a user. As shown in
Non-metal strands 14 may be made from various materials, such as natural fibres or cellulose (hemp, flax, etc.), mineral-based fibres (basalt, etc.), fibreglass, polymer-based, or composite. It was found that woven fibreglass strands provided adequate results, and in the discussion below, mesh structure 12 will be discussed in terms of fibreglass strands 14. However, it will be understood that mesh structure 12 may be woven from other non-metal materials, provided that they have adequate structural properties, which may include properties such as tensile strength, durability, tear-resistance, etc. and may be non-conductive, non-magnetic, and/or chemically inert, depending on the intended application.
Fibreglass strands 14 are typically made from glass fibres embedded in a carrier material, typically a polymer, such as a blend of suitable acrylic copolymers, thermoset polymers, etc. As such, fibreglass may also be referred to as fibre-reinforced plastic or glass-reinforced plastic. The type of polymer and glass used may be selected based on desirable properties, such as cost, strength, etc. A common type of glass fibre used in fibreglass is E-glass, which is used in the example discussed below. Other types of glass fibres may also be used.
Fibreglass strands 14 are often finished with a surface coating, such as resins, if required to provide certain properties or characteristics. This may or may not be required, depending on the materials used to fabricate strands 14. As glass is generally smooth and may be difficult to adhere to intumescent material, the surface of strands 14 may be functionalized to improve adhesion between strands 14 and intumescent material 18 during or after manufacturing. In some cases, this may involve applying a non-waterproof coating, such as a hydrophilic coating. The surface of strands 14 may be functionalized in other ways and using other techniques other than applying a suitable coating.
The coating selected to finish strands 14 may have a negative impact on the initial fire protective properties of intumescent mesh 10 but may be selected to improve the adhesion of intumescent material 18 to strands 14 or other properties. The coating may also be selected to provide some high-temperature protection to fibreglass strands 14, such as to reduce the likelihood of cracking at high-temperatures. It will be understood that other examples of mesh structure 12 may be used, provided that the materials and dimensions are adequate for the intended purpose.
In one example, specifications of a fibreglass mesh structure 12 may be as follows:
Referring to
Modifications to this formula may be made, with some components being replaced, removed, or added as will be recognized by those skilled in the art. For example, several additional intumescing or char-forming components may be added to the intumescent coating 18 blend to enhance fire properties, durability, appearance, curing time, etc. These additives may include sodium borates such as disodium octaborate tetrahydrate, boric acid, boric oxide, zinc borate, zinc oxide, titanium dioxide, melamine, aluminum hydroxide, magnesium hydroxide, etc.
Intumescent coating 18, along with mesh structure 12, may be designed to be suitable for fire-prevention purposes within a specified temperature range, such as may be experienced in a wild-fire setting such as may occur in a forest setting or a brush-covered area, or in a residential or commercial area. Intumescent coating 18 is designed to have an activation temperature above which it swells, as showing in
Below are the results of tests performed on a fibreglass intumescent mesh with 1/4 inch openings, and about 0.13 lb/sq ft. (0.63 kg/m2) of intumescent material 18 applied to mesh 12:
During testing, it was noted that, relative to an intumescent mesh of a similar size but based on a wire grid instead of a woven fibreglass grid, the initial activation of intumescent coating 18 was slower and resulted in an initial spike in temperature across intumescent mesh 10. However, intumescent mesh 10 made from woven fibreglass mesh structure 12 lasted longer than the metal mesh structures, despite the fact that fibreglass will typically fail at a lower temperature than metal. It is believed that this is due to the lower thermal-conductivity of fibreglass relative to metal. It is further believed that, as metal conducts heat more quickly, a metal mesh will apply heat to intumescent coating 18 more quickly, which causes a faster activation period, but may also lead to premature failure based on the same reasons. These observations were observed even though fibreglass tends to soften at around 850° C., depending on the type of fibreglass.
In other examples, fibres other than fibreglass may be used, such as cellulose fibres and coated with intumescent coating 18. In these examples, suitable additives or coatings may be selected to improve properties and allow for sufficient structural strength in high temperature applications.
Preferably, intumescent mesh 10 coating 18 is sufficiently flexible to avoid spalling, flaking, cracking, chipping or otherwise falling off the flexible mesh structure 12 as mesh 10 is manipulated and bent such as may occur during transport or installation. In some examples, this may require intumescent mesh 10 to bend around 90-degree corners, bend around curved surfaces, fold in half or nearly in half, etc. In general, mesh 10 may be flexible but may not retain the shape as may be the case with a metal mesh. In such a case, fasteners or other structural members may be used to retain the shape after or during installation. Intumescent mesh 10 may be designed to be used in outdoor applications where intumescent coating 18 is exposed to the elements without degrading, or to degrade a desired amount over a predetermined time period. Depending on the climate of a given installation location, intumescent coating 18 may be modified to withstand higher or lower temperatures, or to have improved protection against moisture, UV degradation, etc. In this manner, intumescent coating 18 may be designed to withstand temperature extremes that may be encountered, such as low temperatures that may be encountered in cold climates, and the high temperatures that may be encountered in warm climates, and when exposed to direct sunlight without expanding or swelling prematurely. In one example, intumescent coating 18 may be designed to satisfy a standardized accelerated weathering test known as ASTM G-154. This test is designed to accelerate the breakdown of materials but overexposures of extreme heat, UV, and condensation. Intumescent coating 18 may be designed to withstand exposures of this test and maintain adhesion of the coating 18 to mesh structure 12 without breakdown.
Referring to
Referring to
As noted above, it has been found that a mesh size of about ¼± 1/16 inches, with an adequately thick intumescent coating 18 may provide a desired level of passive fire protection, while still allowing for sufficient airflow through intumescent mesh 10. In one example, suitable airflow may be achieved when openings 16 account for between about 25-75% of the area of intumescent mesh 10. When the intumescent coating 18 is exposed to temperatures at or above the activation temperature, intumescent coating 18 swells to seal openings 16 and prevent airflow through intumescent mesh 10.
Referring to
In one example, referring to
In another example, referring to
The dimensions of intumescent mesh 10 will vary depending on it's intended use and application. In one example, a roll that is 3-4 feet wide and 50 feet long may be made that is small and light enough to be handled by a single worker without strain. Other dimensions may also be used depending on the intended used and preference of the user. Those skilled in the art will be able to make any necessary modifications to the equipment for making and handling the intended size of intumescent mesh 10.
Electrical conductivity of fibreglass is a similar format to wirecloth however fibreglass is weaker and frail in a simplistic format that would compare to wirecloth. It will fail in industrial applications such as wood power poles and cross arms.
A typical roll may be 3 ft×50 ft (0.91 m×15.2 m) for a total of 150 sq.ft. (13.9 m2), and will weigh about 10.8 lbs (4.90 kg)
In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements.
The scope of the following claims should not be limited by the preferred embodiments set forth in the examples above and in the drawings but should be given the broadest interpretation consistent with the description as a whole.
Filing Document | Filing Date | Country | Kind |
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PCT/CA2021/051175 | 8/24/2021 | WO |
Number | Date | Country | |
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63069670 | Aug 2020 | US |