Ultra-thin fire protection shield

Abstract

Flexible fire protection shield comprising a microporous layer of metal oxide and at least one mica layer characterized in that the microporous layer is sandwiched between the mica layer and another mica layer or a polyimide aerogel layer wherein the mica layers and the aerogel layer have a thickness below 0.3 mm and wherein the layers are sewn together using a heat resistant yarn having a diameter below 0.5 mm and a tex below 250 g / 1000m, wherein that the fire protection shield has a total thickness below 6 mm, preferably below 5 mm, most preferably below 2.2 mm.

Description

[0001] Ultra-thin fire protection shield

[0002] FIELD OF THE INVENTION

[0003] BACKGROUND OF THE INVENTION

[0004] Fire protection shield aims to prevent or limit the damage caused by fire by providing a barrier against flames, heat, and smoke. It is common to use microporous insulation material when thin and light solution is targeted.

[0005] Microporous insulation materials are known per se, for instance from GB1580909 and US6936326 and comprise a porous metal oxides material and in addition thereto an opacifier and optionally a reinforcing fiber. In ASTM C168, microporous insulation is defined as "material in the form of compacted powder or fibres with an average interconnecting pore size comparable or below the mean free path of air molecules at standard atmospheric pressure. Microporous insulation may contain opacifiers to reduce the amount of radiant heat transmitted". Microporous materials are characterized by a very low thermal conductivity of less than 40 mW / mK and even significantly lower and are often used as thin insulating panel in a variety of industrial applications as well as in construction.

[0006] Besides a good insulation, the fire protection shield should also meet the following criteria:

[0007] 1. Integrity: The ability of a material to maintain its structural integrity during exposure to fire. A material with good burn-through properties will resist deformation, collapse, or the formation of openings that allow flames and heat to penetrate through.

[0008] 2. Flame Penetration: The resistance of a material to the passage of flames from one side to the other. A material with good burn-through properties will inhibit the spread of flames.

[0009] 3. Absence of flame spreading: the ability of the material to not spread the flame by combustion on the flame side.

[0010] US6818273 describes a microporous heat insulation body comprising a 5 mm core of compressed heat insulation material containing from 30 to 90 percent by weight of a finely divided metal oxide. The molded body is then coated with a 0.1 mm thick mica sheet on both side and adhered with an adhesive. The density is between 300 to 560 kg / rr The heat insulation bodies are however rigid. EP3317461 Bl describes cylindrical thermal protection sheets comprising a flexible sandwich-like composite insulating system, which comprises a middle layer of flexible microporous silica or alumina thermal insulation material sandwiched by other layers. No layers of mica are disclosed.

[0011] DE202016008816 U1 discloses fire-retardant multilayers comprising outer textile layers sandwiching an intumescent layer, whereby the layers are connected via sewing with a heat-resistant yarn.

[0012] WO 2023 / 182385 Al relates to a flame retardant material comprising an inorganic fiber cloth and a heat insulating material layer which are attached to each other via thread sewing. The heat insulating material may comprise metal oxide particles. Transport industries are always looking for thinner and lighter fire and heat shield for obvious ecological reasons. Therefore, there is a need to decrease the thickness of the fire protection shield while maintaining its flexibility.

[0013] SUMMARY OF THE INVENTION

[0014] It is therefore a first object of the invention to provide a flexible fire shield having a total thickness below 6mm which provides a high thermal insulation up to 1200°C while keeping integrity of the material and avoiding flame penetration.

[0015] It is another object of the invention to provide a method for producing these flexible fire protection shield and the use of such flexible fire protection shield to maintain the cold side of the shield to a temperature below 550°C when subjected to an ISO 834 temperature -time curve for 120 minutes. The temperature on the hot face following the ISO 834 temperature -time curve for 120 minutes is 1050°C.

[0016] According to a first aspect, the invention provides a flexible fire protection shield comprising a microporous layer of metal oxide and at least one mica layer. The microporous layer is sandwiched between the mica layer and another mica layer or a polyimide aerogel layer. The mica layers and the aerogel layer have a thickness below 0.3 mm. The layers are sewn together using a heat resistant yarn having a diameter below 0.5 mm, preferably 0.2-0.4 mm and a tex below 250 g / lOOOm. The Tex is preferably between 200 and 220 g / lOOOm. The tex and the diameter are essential such as the conductivity of the yarn and then the diameter of the hole created by melting of the yarn do not jeopardize the global insulation of the shield.

[0017] A heat-resistant yarn is a type of yarn specifically designed to withstand high temperatures without degrading or losing its physical and chemical properties. These yarns are often made from specialized fibers or treated materials to provide durability and functionality in extreme heat conditions. Yarns are made of Aramid Fibers, stainless steel, carbon fibers, polyimide fibers, Polybenzimidazole fibers, Glass fibers, Ceramic fibers, Basalt fibers or Silica fibers, quartz fibers, stainless steel reinforced Kevlar fibers or a combination of these materials to make yarns. The mica layer is a mica paper having a thickness below 0.3mm, preferably below 0.15 mm. The mica paper is flexible at the opposite of a mica sheet. The mica paper is a mica reinforced with heat resistant flexible binder such silicone binder.

[0018] The flexible fire protection shield has a total thickness below 6mm, preferably below 5 mm and most preferably below 2.2 mm.

[0019] The fire protection shield is flexible. The term flexible is understood to mean that the support can be wrapped around a cylindrical surface, which surface has a bending radius of 5 mm.

[0020] The microporous layer has a thickness preferably between 0.5 and 2.4mm, most preferably between 1 and 2 mm.

[0021] The density of the microporous layer is in the range of 250- 450 Kg / m^, preferably between 300-400 kg / n The microporous layer has a thermal conductivity between 23-36 mW / mK at 400°C.

[0022] The microporous layer comprises 30 to 90 wt% of metal oxide, 5-60 wt % of an opacifier material, 1 to 10 % of inorganic fibres and 0 to 50% of filler. The microporous layer is free of aerogel and free of xonotlite. The metal oxide are in the form of particles having a size ranging from 12 - 100 nm measured by laser diffraction analyser technique.

[0023] The metal oxide is chosen among -silica, alumina and preferably is pyrogenic silica or pyrogenic Alumina or mixed oxide or pyrogenic . The surface areas of the metal oxides are ranging from 50-400 m^ / g. The surface area is measured by the BET method (Brunauer, Emmett and Teller) in accordance to ISO 9277-2010.

[0024] The opacifier is selected from titanium dioxide, iron titanium oxide, zirconium silicate and iron oxide and mixtures thereof, in an amount of 12-40%, preferably 15-40%.

[0025] Inorganic fibers are also present between 1 to 10%. These fibers can be of E, S, R glass in composition, silica fibers as well as alumina fibers or ceramic fibers and body soluble fibers by composition (alkaline oxide and alkaline earth oxide contents > 18% with temperature limit over 1000°C).

[0026] Mixed fibers are also possible as well as small addition of organic or cellulosic fibers (0-3%). The fibers diameter can be 0.2-12 microns with of 3-12 mm in length, preferably, 0.3-7 microns in diameter and 3-6 mm in length.

[0027] In a further implementation, the optional filler in the microporous powder composition is a material chosen from the group of water glass, precipitated and amorphous silica, calcium silicate, perlite, calcium sulphate, including gypsum materials, aluminum phosphates, borides of aluminum, titanium, zirconium, calcium, silicides, basic oxides in an amount of 0-30%, preferably higher than 5 wt%.

[0028] Silicides may be chosen among calcium silicide or calcium aluminum silicide.

[0029] Basic oxides may be chosen among magnesium oxide, calcium oxide and barium oxide oxides.

[0030] The heat resistant yarn is made of E glass or quartz and preferably stainless steel reinforced Kevlar if the temperature of use is higher than 1000°C.

[0031] The sewing defines (stitching) pitches size of 30 x 30 mm, preferably 25 x 25 mm.

[0032] In a preferred embodiment, the microporous layer is sandwiched between two mica papers.

[0033] In this embodiment a polyimide aerogel layer having a thickness below 0.3 mm is present between the microporous layer and only one mica layer.

[0034] The fire protection shield of the present invention withstands a temperature up to 1200°C, the fire shield also provides resistance to flame: it indeed keeps its integrity facing the effect of a Bunsen a 850°C up to 1100 °C (Burn through properties). The combination of the mica paper and the microporous layer also improves the acoustic of the shield.

[0035] The fire protection shield is also self-extinguishing after burner removal and prevents autoignition at the cold side.

[0036] The invention also relates to a method for producing a flexible fire protection shield comprising the step of sewing the at least 3 layers with a heat resistant yarn having a diameter below 0.5 mm, preferably 0.2-0.4 mm and a tex below 250 g / lOOOm characterized in that the flexible fire protection shield has a thickness below 6 mm, preferably below 2.5 mm. The microporous layer is prior pressed to obtain the microporous layer with the desired density.

[0037] A third aspect of the invention is the use of the flexible fire protection shield as described hereabove subject to a an ISO834-2019 temperature-time curve for 120 minutes wherein the temperature at the cold side remains below 550°C, preferably 400°C.

[0038] FIGURE

[0039] Figure 1 illustrates the test firing of Examples 1 and 2. The temperature on the cold side of Example 1 (EXI) is represented by two temperature curves (one dotted and one solid), which were measured by two thermocouples attached to the cold side of Example 1. Similarly, the temperature on the cold side of Example 1 (EXI) is represented by two temperature curves (one dotted and one solid), which were measured by two thermocouples attached to the cold side of Example 2.

[0040] EXAMPLES

[0041] These and other aspects of the invention will be further elucidated in following examples.

[0042] Example 1

[0043] A fire protection shield made of a layer of 1.5 mm of microporous layer comprising silica oxide having a density of 400 kg / m^ was sandwiched between two mica papers having thickness of 0.12 mm. The three layers are then sewn with a stainless steel reinforced Kevlar having a diameter of 0.2mm and a tex of 215 mm. The microporous layer was composed of 59% of pyrogenic silica, 38% of rutile and 3 % of silica fibers.

[0044] The fire test according to ISO 834- 2019 was conducted as following; an electrical oven was used and heated up 550 °C then the front plate was removed and replaced by the fire shield. The temperature in the oven was then raised according to ISO 834 from 550 °C up to 1050°C after 2 hours for partition application.

[0045] As it can been on the graph, using a ultra thin fire shield of 1.74 mm allows to keep the temperature of the cold side under 550°C when the hot side faces a temperature curve according to ISO 834 up to 1050 °C after 120 minutes.

[0046] Example 2

[0047] By adding a polyimide aerogel film of 0.17 mm, the temperature on the cold face remains below 400°C.

[0048] For both examples, no flame spreading was observed and the shield maintained its integrity.

[0049] Burn through properties:

[0050] The samples remained intact after 30 minutes exposed to an 850°c flame from a bunsen burner.

Claims

CLAIMS1. Flexible fire protection shield comprising a microporous layer of metal oxide and at least one mica layer characterized in that the microporous layer is sandwiched between the mica layer and another mica layer or a polyimide aerogel layer wherein the mica layers and the aerogel layer have a thickness below 0.3 mm and wherein the layers are sewn together using a heat resistant yarn selected among aramid fibers, stainless steel fibers, carbon fibers, polyimide fibers, polybenzimidazole fibers, glass fibers, ceramic fibers, basalt fibers or silica fibers, quartz fibers, stainless steel reinforced Kevlar fibers or a combination of these materials, having a diameter below 0.5 mm preferably 0.2-0.4 mm, said yarn having a tex below 250 g / lOOOm wherein that the fire protection shield has a total thickness below 6 mm, preferably below 5 mm, most preferably below 2.2 mm.

2. Flexible fire protection shield according to claim 1 wherein the mica layer is a mica paper.

3. Flexible fire protection shield according to any one of the previous claims wherein the microporous layer has a thickness between 0.5 and 2.4mm, preferably between 1 and 2 mm.

4. Flexible fire protection shield according to any one of the previous claims wherein the density of the microporous layer is in the range of 250-450 kg / m3, preferably between 300-400 kg / m3.

5. Flexible fire protection shield according to any one of the previous claims wherein the metal oxide of the microporous layer comprises 30 to 90 wt% of metal oxide, 5-60 wt % of an opacifier material, 1 to 10% of inorganic fibers and 0 to 50% of filler.

6. Flexible fire protection shield according to any one of the previous claims wherein the metal oxide is chosen among -silica, alumina and preferably is pyrogenic silica or pyrogenic Alumina with surface areas ranging from 50-400 m2 / g measured according to ISO 9277-2010.

7. Flexible fire protection shield according to claim 5 or 6 wherein the opacifier is selected from titanium dioxide, iron titanium oxide, zirconium silicate and iron oxide and mixtures thereof, in an amount of 12-40%, preferably 15-40%.

8. Flexible fire protection shield according to any one of claim 5 to 7 wherein the filler is chosen from the group of water glass, precipitated and amorphous silica, calcium silicate, perlite, calcium sulphate, including gypsum materials, aluminum phosphates, borides of aluminum, titanium, zirconium, calcium, silicides, basic oxides in an amount of 0-50 wt.%, preferably higher than 5 wt% .

9. Flexible fire protection shield according to any one of the previous claims wherein the heat resistant yarn is made of glass, quartz preferably stainless steel reinforced Kevlar.

10. Flexible fire protection shield according to any one of the previous claims wherein the microporous layer is sandwiched between two mica papers.

11. Flexible fire protection shield according to the previous claim wherein an polyimide aerogel layer having a thickness below 0.3 mm is present between the microporous layer and only one mica layer.

12. A method for producing a flexible fire protection shield according to any one of the previous claims comprising the step of sewing the at least 3 layers with a heat resistant yarn having a diameter below 0.5 mm, preferably 0.2-0.4 mm and a tex below 250 g / lOOOm characterized in that the flexible fire protection shield has a thickness below 6 mm, preferably below 2.5 mm.

13. Use of the flexible fire protection shield according to claim 10 subject to an ISO834 temperature-time curve for 120 minutes wherein the temperature at the cold side remains below 550°C.

14. Use of the flexible fire protection shield according to claim 11 subject to an ISO834 temperature-time curve for 120 minutes wherein the temperature at the cold side remains below 400°C.

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