Aqueous compositions, a process for curing them and the cured product thereof

Abstract

The present invention provides an aqueous composition comprising an aqueous vehicle and, carried in the aqueous vehicle: (a) potassium silicate, wherein the amount of potassium silicate is from about 9% to about 40% by weight based on the total weight of the composition; (b) zinc borate acting as a curing agent, wherein the amount of zinc borate is from about 1% to about 10% by weight based on the total weight of the composition; (c) a calcium component capable of releasing calcium ions within the composition through alkaline dissolution, wherein the amount of the calcium component is from about 12% to about 22% by weight based on the total weight of the composition, such that the released calcium ions act as catalyst for zinc borate induced curing. It also provides a process for curing the composition and a cured composition, for example a coating, thereof. Products to which the composition is applied may exhibit better fire performance.

Description

Aqueous compositions, a process for curing them and the cured product thereofField of the Invention

[0001] This invention relates to improved fire performance of products and in relation to compositions such as aqueous compositions that confer / impart good fire performance and a process for curing such compositions and the cured product thereof. Furthermore the present invention relates to articles / products to which a composition of the invention has been applied and cured thereon.Background to the Invention

[0002] It is always a desirable property of construction materials to have a good fire performance and in particular to be resistant to fire.

[0003] Various tests have been developed to determine fire properties. A wide variety of small scale and large scale fire tests are being used to simulate actual fire performance.

[0004] Examples of laboratory fire tests are the "Cone Calorimeter Heat Release test" (ISO 5660-1), the "Limiting Oxygen Index" (LOI) test (ISO 4589-2), the "Heat of Combustion" test (ISO 1716) and the "Ignitability of Products Subjected to Direct Impingement of Flame test" (ISO 11925-2).

[0005] Fire performance of a product such as an insulation material / product in a real fire situation can be evaluated using the Single Burning Item (SBI) test (EN13823). This test method involves measuring flame spread length, average rate of heat release (HRRav), total heat release (THR) after "t" seconds, propensity to produce flaming drips and the rate of smoke production (SPR). The test procedure simulates the performance of products such as insulation products fixed to the walls and ceiling of a small room where the single burning ignition source in the corner of the room is a nominal 30 kW heat output. The burner is comparable to a waste-paper basket on fire in the corner of a room. Accordingly, EN 13823 is a test method which simulates a real fire situation and thus provides very useful information regarding the fire performance of products such as an insulation material in a real fire situation.

[0006] The performance of the specimen is evaluated for an exposure period of 20 minutes. During the test, the heat release rate (HRR) is measured by using oxygenconsumption calorimetry. The smoke production rate (SPR) is measured in the exhaust duct based on the attenuation of light. The fall of flaming droplets or particles is visually observed during the first 600 seconds of the heat exposure on the specimen. Lateral flame spread is also measured.

[0007] The fire performance of a material is assessed in EN 13823 by monitoring the rate of fire growth and the rate of smoke production after threshold values for the average heat release rate, total heat release rate, average smoke production rate and total smoke production rate have been exceeded beyond defined reference values in the specification.

[0008] The fire performance rating / classification parameters of the SBI test are fire growth rate index (FIGRA), lateral flame spread (LFS), and total heat release at 600 seconds (THRgoos). Additional rating / classification parameters are defined for smoke production as smoke growth rate index (SMOGRA) and total smoke production at 600 seconds (TSPgoos), and for flaming droplets and particles according to their occurrence during the first 600 seconds of the test.

[0009] The performance of closed cell thermal insulation foams in the SBI test varies, depending inter alia on the chemical type of foam resin being tested, the type of blowing agent retained in the foam and the presence or absence of flame retardants.

[0010] The fire testing and rating / classification standards for construction products have been harmonized in the EU in European Standard EN 13501-1. The European Reaction to Fire rating / classification system (Euro classes) is the EU common standard for assessing the qualities of building materials in the event of a fire, and covers three elements: a class based on combustibility and contribution to fire; a sub-class based on total smoke propagation / emission level; and a sub-class based on the amount of flaming droplets and particles when the material is exposed to fire. The Euroclass system for evaluation of the fire performance of building materials involves the classification of building materials into seven classes based on their reaction-to-fire properties. The classes are as follows: Al, A2, B, C, D, E and F. The Euroclass system classifies the fire performance of materials based on their performance in several standard test methods including: EN ISO 11925-2; EN13823; EN ISO 1716 and EN ISO 1182. Products in the Euroclass "A" classes include inorganic and ceramic products with little or no organic material. Examples of products in the Euroclass B class include gypsum boards with thin facing materials. Other materials such as closed cell foams may achieve Euroclass "C" classification.

[0011] In relation to insulation products that are used for thermal insulation in construction, there not only is it desired to have a good fire performance it is also desirable of course to have good thermal insulation properties. Thermal insulation properties are often determined using thermal conductivity values (lambda or X value). All thermal conductivity values given herein are determined according to EN 12667 unless otherwise stated.

[0012] So for products which are used in construction it is desirable to improve fire performance wherever possible. For example for products in lower Euroclass ratings / classifications it is desirable to improve them so that they achieve better Euroclass ratings. And of course while it would be desirable to confer an A-class rating on all products the objective of the present invention is to improve the Euro class rating of products.Summary of the Invention

[0013] In compositions of the invention silicate compositions which react with divalent metal compounds, in the presence of a curing agent, to form cured and / or cross-linked products.

[0014] Such cured and / or cross-linked products can be used in any desired form. For example they may be used as coatings such as protective coatings, binders, matrices, inorganic fillers etc.

[0015] Of particular interest in the present invention is the use of a composition of the invention to impart improved fire performance on a product / substrate. The improved performance can be used by applying a composition of the invention onto the product / substrate or incorporating it into the body of the product / substrate. It may be incorporated into the body of the product / substrate during manufacture of the product / substrate.

[0016] For example a layer of a composition of the invention may be applied. Desirably all exposed surfaces of the product / substrate have a composition of the invention applied thereto optionally a layer thereof. For example a product / substrate may be encapsulated by a composition of the invention.

[0017] A composition of the invention when cured / dried can form a material that can be considered to be a Class A rated material under Euroclass ratings.

[0018] Particularly, the present invention relates to a composition that can be cured to form a (Class-A) non-combustible coating which can be applied on a variety of substratesincluding thermal insulation substrates in order to improve the overall fire rating thereof. For example products that had a lower rating than Class A may achieve a Class A rating using a composition of the invention.

[0019] The present invention provides an aqueous composition comprising an aqueous vehicle and, carried in the aqueous vehicle: potassium silicate, wherein the amount of potassium silicate is from about 9% to about 40 % by weight based on the total weight of the composition; zinc borate, wherein the amount of zinc borate is from about 1 % to about 10%, such as about 1 % to about 8%, for example about 1 % to about 5%, by weight based on the total weight of the composition; and a calcium component, wherein the amount of the calcium component is from about 12 % to about 22 % by weight based on the total weight of the composition.

[0020] It has been found that compositions of the invention can confer / impart good fire performance. This also applies to the process of the invention which is for curing such compositions and also applies to the cured product of a composition of the invention. Furthermore it applies to articles / products of the invention, to which a composition of the invention has been applied or incorporated, and the composition is cured.

[0021] A composition of the invention is flowable and can, for example, be pumped, and / or sprayed. A composition of the invention is in liquid form (in its uncured form).

[0022] It is thought that a composition of the invention may cure through the solid state.

[0023] It is thought that the zinc borate may dissolve in the composition of the invention to a sufficient extent to effect cure. For example it may be considered to act as a catalyst. It is thought that the zinc borate is effective in conjunction with the calcium component which may be a material such as calcium metasilicate. It is thought that the low solubility of the zinc borate contributes to less rapid curing which in turn confers better properties on the cured composition. For example it may be that the released calcium ions act as catalyst for zinc borate induced curing.

[0024] The presence of calcium ions can have a catalysing influence on the formation of covalent bonds in the composition of the invention. A composition of the invention may cure to form a type of "geopolymer".

[0025] This may contrast with other silicate compositions which may cure through dissolution of a different material such as aluminosilicate.

[0026] It is thought that the composition of the invention may be sufficiently alkaline to allow sufficient zinc borate to dissolve to become reactive. Sufficient alkaline dissolution of zinc borate may occur. It may be that a composition of the invention is somewhat alkaline due to alkaline materials, such as alkaline earth materials, present in the composition. Solubility may increase due to alkalinity imparted by alkaline components in the composition.

[0027] Advantageously, the zinc borate has a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm. It initiates cross-linking or curing once solubilised by potassium silicate. The amount of zinc borate is important, too little leads, in the cured product, to poor water resistance whereas too much leads to over-stress in drying and risk of cracking. Hence, it is present in an optimum amount in the composition to achieve the desired results. A component having a mean particle size of less than 50 pm can be considered micronized. The zinc borate is optionally micronized.

[0028] In a composition of the invention it is desirable that the calcium component is water-insoluble or only partially water soluble. The calcium component acts as a calcium ion source. The calcium ions are released by dissociation of the calcium component. Again it is thought that the composition of the invention may be sufficiently alkaline to allow sufficient of the calcium component release sufficient calcium ions.

[0029] Having the two components zinc borate and potassium silicate leads to a slower reaction / curing and thus the composition cures over a somewhat longer time rather than immediately. For example a composition of the invention does not cure in a short period. Such a short period may be less than about 180 seconds, less than about 120 seconds or less than about 60 seconds. The two components zinc borate and potassium silicate which are considered water insoluble or only partially water soluble determine the rate of cure. The solubility is rate determining for cure.

[0030] The zinc borate and the calcium component may act together as co-curing components for curing the composition of the invention.

[0031] Desirably the potassium silicate has a silica to potassium ratio of from about 1.25:1 to about 2.5:1, such as from about 2:1 to about 2.5:1. It is thought that this range of values contributes to good water resistance and overall strength of the cured composition.

[0032] Optionally the amount of potassium silicate is from about 15% to about 40%, such as from about 15% to about 34%, by weight based on the total weight of the composition. Optionally the amount of potassium silicate is from about 18% to about 29% by weight based on the total weight of the composition. The amount is thought to contribute to fire resistance properties in the cured product.

[0033] The potassium silicate may be blended with water for use in solution, for example at a ratio of about 10:1 (water to potassium silicate) to reduce its viscosity.

[0034] The amount of zinc borate may be from about 2 % to about 5%, such as from about 2.5 % to about 5%, optionally from about 2.5% to about 4.5%, for example about 4.2%, all by weight and based on the total weight of the composition.

[0035] Optionally the zinc borate added to the composition of the invention is micronized for example having a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm. A finely divided zinc borate material may make it more reactive within a composition of the invention.

[0036] The ratio of the zinc borate to the potassium silicate, based on the weight ranges above is desirable for the fire resistance properties in the cured product.

[0037] It will be appreciated that components of the composition of the invention that are insoluble in water may be present in the aqueous composition as heterogeneous mixture for example as particulates in the aqueous vehicle such as in the form of a suspension. The composition of the invention may be considered an aqueous dispersion.

[0038] The calcium component may be calcium silicate, and / or calcium metasilicate (for example wollastonite). Optionally the calcium component has a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm. Suitably, the calcium component in the composition is calcium metasilicate or calcium silicate. A desired amount of the calcium component in the composition is from about 12 % to about 22 %, optionally from about 14 % to about 20 % by weight based on the total weight of the composition. The calcium component is optionally micronized.

[0039] The amount of the calcium component may be from about 12% to about 22% by weight based on the total weight of the composition such as about 14 % to about 20% by weight based on the total weight of the composition.

[0040] A composition of the invention may further comprise a thixotrope, such as bentonite, optionally wherein the amount of the thixotrope is from about 0.1% to about1.5% by weight for example from about 0.5% to about 1% by weight based on the total weight of the composition, such as about 0.8% based on the total weight of the composition. A thixotrope confers thixotropic properties on a composition of the invention. The mean particle size of the thixotrope used is suitably from about 65 pm to about 85 pm such as about 70 pm to about 80 pm, for example about 75 pm. Use of a thixotrope is desirable as it may prevent settling. Furthermore, utilising a thixotrope, such as bentonite, that confers fire resistance properties is desirable. The thixotrope confers desirable properties but the composition of the invention still remains flowable, for example it can be pumped or sprayed. Furthermore such a composition does not have any settling of components out of solution over a period of at least 5 hours, such as at least 1 day, for example at least one week. The role of thixotrope is thus to limit settling of solids in the aqueous media to achieve / retain a desired viscosity of the composition.

[0041] A composition of the invention may also comprise an anti-foam agent, such as anti-foam mineral oil. Optionally the amount of the anti-foam agent is from about 0.1% to about 0.4% by weight based on the total weight of the composition. The presence of the anti-foam agent improves substrate wetting and / or increases sprayability of a composition of the invention. Desirably the amount of the anti-foam agent is from about 0.05% to about 0.3% by weight based on the total weight of the composition.

[0042] The anti-foam agent aids substrate wetting. An example of an antifoam agent is one based on mineral oil such as those available under the Foamaster™ brand name from BASF.

[0043] The presence of the anti-foam agent is also thought to reduce stress cracking on drying of the composition.

[0044] A composition of the invention may also comprise glass particles which are optionally glass flakes. Desirably the glass flakes have a mean particle size from about 105 to about 130 pm, optionally wherein the glass flakes are present in an amount from about 2% to about 10% by weight based on the total weight of the composition, such as from about 3% to about 8% by weight based on the total weight of the composition, for example from about 2% to about 7% by weight based on the total weight of the composition. Suitably, the planar thickness of the glass flakes is from about 2 pm to about 8 pm, from about 3 pm to about 7 pm, such as about 5 pm.

[0045] It is thought that the inclusion of glass flakes improves the overall fire performance of the cured composition of the invention. For example the glass flakesmay impart ceramic-like properties. The ceramic like fire behaviour (resistance to >1300°C) comes as a result of chemical interaction between the curing silicate and the glass. They may also provide abrasion resistance.

[0046] In an aqueous composition of the invention the glass flakes may have a mean particle size from about 20 pm to about 40 pm such as from about 27 pm to about 32 pm, optionally wherein the glass flakes are present in an amount from about 5% to about 12% by weight based on the total weight of the composition such as from about 6% to about 10% by weight based on the total weight of the composition, for example from about 7% to about 9% by weight based on the total weight of the composition.

[0047] Desirably two distinct distributions of glass flake size are utilized. Desirably an amount of a grade or type of particle size having a larger mean particle size is used in conjunction with a grade or type of particle size having a smaller mean particle size

[0048] For example the glass flakes within the composition of the invention may include (larger) glass flakes having a mean particle size from about 105 to about 130 pm, for example 120 pm and the glass flakes include (smaller) glass flakes having a mean particle size from about 20 pm to about 40 pm such as from about 27 pm to about 32 pm, for example 30 pm. Suitably the weight ratio of the larger glass flakes to the smaller glass flakes is about 1:2. A composition of the invention may comprise may include (larger) glass flakes having a mean particle size from about 105 to about 130 pm, for example 120 pm without the smaller glass flakes above. Accordingly two distinct distributions of glass flake size are not required and the larger) glass flakes having a mean particle size from about 105 to about 130 pm, for example 120 pm without the smaller glass flakes above may be desired.

[0049] Desirably a composition of the invention further comprises potassium aluminium silicate for example mica. The potassium aluminium silicate may help to stabilize the composition during curing.

[0050] In the context of the present invention potassium aluminium silicate is a distinct component from potassium silicate. Optionally the potassium aluminium silicate has a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm. A component having a mean particle size of less than 50 pm can be considered micronized. The potassium aluminium silicate is optionally in a micronized form. The potassium aluminium silicate may be in the form of mica, for example muscovite mica. Micronized mica such as micronized muscovite mica may be employed.

[0051] Suitably the amount of the potassium aluminium silicate is from about 2% to about 8% by weight based on the total weight of the composition, for example from about 4% to about 6% by weight based on the total weight of the composition.

[0052] Optionally a composition of the invention may include a toughening / flexibilising agent / component, optionally in the form of fibres, for example ceramic fibres. Flax, such as flax in the form of flax fibres or hemp, such as hemp in the form of hemp fibres can additionally or alternatively be used as a toughening / flexibilising agent. Optionally the amount of the toughening / flexibilising agent is from about 0.5% to about 3% by weight based on the total weight of the composition. Desirably the ceramic and / or flax and / or hemp fibres have a length from about 1 mm to about 3 mm, such as about 2 mm.

[0053] Desirably a composition of the invention has a viscosity of from about 4000- 4500cP. Viscosity may be measured by digital rotational viscometer with various calibrated spindles.

[0054] Optionally a composition of the invention may be in the form of a two-part composition. For example it may be provided / stored in two separate parts which are then mixed immediately before use. A composition of the invention in two part form is more storage stable.

[0055] In a two-part composition of the invention the zinc borate, optionally together with a thixotrope, is desirably present in a different part of the composition than the calcium component.

[0056] For example, a two-part composition of the invention may be described as having a Part A and a Part B. A composition of the invention may have a Part A and Part B, wherein Part A includes the potassium silicate, the calcium component, and optionally one or more of: a thixotrope, an anti-foam agent, glass flakes, and potassium aluminium silicate, and a toughening / flexibilising agent; and Part B includes the zinc borate, optionally together with a thixotrope.

[0057] The pot life of a composition of the invention prior to curing is from about 15 minutes to about 60 minutes, such as about 20 to about 60 minutes, for example from about 15 minutes to about 30 minutes, such as about 20 minutes. In relation to a two- part composition it will be understood that the pot life refers to the pot life of the composition as and from the time the two parts are brought together. The composition is suitably applied in multiple thin coats, such as of thickness about 200-300 pm per coat.The cure time for each coat in warm air (70 °C) to achieve a dry and firm coating is within the range from about 5 minutes to about 10 minutes.

[0058] A composition of the invention may be provided when Part B and Part A are combined for example either at about 6-12% w / w, suitably at about 8-10% w / w, such as about 8.5% w / w , where about 8.5 g of Part B is added to 100 g of Part A or at a volumetric ratio of Part A to Part B from about 5:1 to about 12:1; desirably about 6:1 to about 11:1, such as from about 7:1 to about 10.5:1 for example from about 8:1 to about 9:1.

[0059] The viscosity of Part A may be from about 5000-6000cP, while the viscosity of Part B may be from about 2500-3000cP. Suitably the viscosity of the composition according to the present invention is from about 4000-4500cP. The viscosities are as measured by a digital rotational viscometer with various calibrated spindles.

[0060] Where a composition of the invention is in two-part form it is desirable that each part is in liquid form. Where a composition of the invention is in a two-part form each part of the composition is desirably flowable and can, for example be pumped, and / or sprayed. Accordingly it is possible to mix the two parts of a two-part composition by taking separate feeds for each part of the composition and combining the feeds during pumping and / or spraying. And of course the respective feed rates of each part of the composition can be utilised to combine the two parts of the composition in a desired mixing ratio such as a desired volume or weight ratio.

[0061] Optionally application of a composition of the invention is by atomisation.

[0062] A spray nozzle or head can be used for the dispersion of the liquid composition of the invention by the formation of a spray.

[0063] It will be appreciated that any desired amount of a composition of the invention may be applied to a substrate. However the present inventors have found that the composition can be applied in an amount of from about 1 kg / m2to about 5 kg / m2such as from about 2 kg / m2to about 4 kg / m2such as about 3 kg / m2. These amounts are the weight of composition applied per m2of the surface of the substrate.

[0064] A process of the invention may include applying a composition of the invention to a substrate and / or otherwise incorporating a composition of the invention into a substrate.

[0065] The invention also provides a process for applying the composition of the invention onto a substrate, comprising the following steps:a) applying the composition to a surface of the substrate, optionally wherein the composition coats at least a part of the substrate; b) curing the composition optionally by allowing the composition to cure or by exposing the composition to curing conditions, such as from about 5 to 10 minutes at about 40 to 90°C; c) optionally repeating the above steps on other surfaces of the substrate; and / or d) optionally applying a further amount of the composition to already cured composition; and / or e) optionally repeating step d).

[0066] The thickness of the cured composition, for example a coating may be from about 1 to about 2 mm for example about 0.8 to about 1.5 mm such as about 1 to about 1.2 mm. A composition of the invention may lose at least 20%, such as at least 25%, for example at least 30%, such as about 35%, by weight based on the total weight of the composition of water during curing.

[0067] The substrate on which the composition can be applied, or otherwise incorporated includes a thermal insulation product such as a foam body, whether open or closed cell, an insulation panel optionally with an insulating core and one or more metallic skins, a hydrophilic substrate such as an inorganic hydrophilic substrate including silica substrates, an aerogel, a core for a vacuum insulation panel, a vacuum insulation panel, an envelope of a vacuum insulation panel etc. The foam body may be formed from PUR (polyurethane), PIR (polyisocyanurate), PS (polystyrene) such as EPS (expanded polystyrene) and XPS (extruded polystyrene) and phenolic foams.

[0068] A composition of the invention has been found to adhere well to metal materials which can include the vacuum retaining envelope of a vacuum insulation panel. Such envelopes are often metalized polymer films. Typically the metal in the metalized polymer film is aluminium. Other metals such as steel for example stainless steel may be employed.

[0069] It will be appreciated that application of a composition of the invention to any substrate including those above should improve the overall performance of that substrate in fire tests. This is particularly so where at least the exposed surfaces have a composition of the invention applied thereto. In particular it should be possible to utilize a composition of the invention to achieve a better Euroclass rating for a substrate as compared to the same substrate without a composition of the invention used a control.

[0070] A composition of the present invention has been found suitable for application as a coating to a substrate is a vacuum insulation panel, optionally in multiple layers.

[0071] The invention also relates to a cured composition, for example a coating, obtained by curing the composition of the invention optionally by a process of the invention.

[0072] Optionally the density of the cured composition, for example a coating, is from about 1200 kg / m3to about 1300 kg / m3.

[0073] It has been determined that a cured composition of the invention has a resistance to hydrocarbon flame temperatures (for example a propane burner) from about 1100°C to about 1300°C, such as about 1300°C.

[0074] It has also been observed that the cured composition of the invention has a low heat capacity and low thermal transmission for a ceramic-like material.

[0075] For example the calorific value of the cured composition, is from about 0.6 MJ / kg to about 0.8 MJ / kg as determined according to EN ISO 1716 standards. This means that a high rating can be achieved under Euroclass rating. For example these values pass the threshold for Euro class Al (<2 MJ / kg). Compositions of the invention have achieved a calorific value of the cured composition, of less than about 0.6 MJ / kg as determined according to EN ISO 1716 standards. Values less than about 0.4 MJ / kg, such as less than about 0.2 MJ / kg and even less than about 0.1 MJ / kg have been achieved with compositions of the invention as determined according to EN ISO 1716 standards.

[0076] The invention also relates to a substrate, such as an insulation product comprising the composition of the invention and / or the cure product of the invention, optionally wherein the composition is in the form of a coating.

[0077] Compositions of the invention can be applied by any suitable method including direct application utilizing an applicator or spraying. Compositions of the invention are suitable for application by spraying.

[0078] The composition of the inventions is optionally in two-parts but it can be used as a water based coating. It may lose approximately 35% by weight of water on drying followed by solid state curing to deliver a non-combustible material for example in the form of a film or layer. That cured material has a low density (for example about 1200kg / m3). It also has resistance to hydrocarbon flame temperatures up to 1300°C. The cured composition also has surprisingly low heat capacity and low thermal transmission for a material that otherwise performs as a ceramic-like material.

[0079] Drying of a composition of the invention may be carried out using heat such as drying at from about 60°C to about 80 °C, such as from about 65°C to about 75°C, for example at about 70°C optionally in an oven.

[0080] Drying may be carried out between sequential applications of the composition. For example composition may be applied and then dried for a time before a second application on top of the (first) dried composition.

[0081] While it will be appreciated that some curing will occur during drying, desirably curing is carried out by application of heat also. Curing may be carried out from about 40°C to about 90°C, such as from about 65 °C to about 75°C, for example at about 70°C optionally in an oven. The time period required for the curing may be from about 6 to 12 hours. This may include time to build up a coating thickness which can be handled but not fully dried or cured, followed by a further period of post-cure which can either be immediate by immediate exposure to elevated temperature or an overnight batch cycle in an elevated temperature.Detailed Description of the Invention

[0082] An example of the composition of the invention was formulated as follows - Table 1 gives the composition broken down by each part of the composition and Table 2 gives the overall composition:Table 1Table 2

[0083] The composition of the invention set out in Table 1 / Table 2 above was applied to a vacuum insulation panel (VIP) so that the VIP was encapsulated by the cured composition. The VIP was an Optim-R™ VIP available from Kingspan Insulation Limited in the UK. The composition of Table 1 was mixed with a Part B to Part A ratio of about 10% by weight to give the composition of Table 2.

[0084] Five layers were applied by brushing, each layer having a thickness of about 300 pm all the way about the VIP. (This gives a total thickness of about 1.5 mm which dries to about 1.2 mm.) The composition totally encapsulated the VIP.

[0085] The composition was cured allowed to cure for about 10 minutes in a well ventilated 70°C oven between coats. Post curing was done overnight under the same conditions.

[0086] The result was a VIP coated on all surfaces / encapsulated in the cured material.

[0087] Various tests of compositions of the invention were tested according to the various tests set out below:

[0088] BS EN ISO 1716: Determination of the gross heat of combustion (calorific value)

[0089] Four compositions according to the invention were tested according to BS ENISO 1716 standard and achieved a calorific value between 0.6-0.8 MJ / kg such as about 0.7145 MJ / kg , thus passing the threshold for Euroclass Al (<2 MJ / kg). Table 3 below provides calorific values achieved for listed Compositions 1-4 according to the present invention as measured according to BS EN ISO 1716. All percentages are percent by weight based on the total weight of the composition. The composition is cured. The curing conditions is allowed to dry and an overnight post cure for 18 hours. Then the cured material is ground to an IKA A10 mill and 0.5 grams of the resultant powder was tested according to BS EN ISO 1716.

[0090] Table 3

[0091] It will be appreciated that the overall calorific value will depend on the substrate to which a composition of the invention is applied.

[0092] BS EN 13823: Thermal attack by single burning item (SBI)In a separate SBI test (EN 13823), a VIP as described above to which a composition as described above composition of the invention set out in Table 1 / Table 2 above was applied to a vacuum insulation panel (VIP) Optim-R™ to form a VIP coated on all surfaces / encapsulated in the cured material. Five layers of the composition were applied by brushing, each layer having a thickness of about 300 pm all the way about the VIP. (This gives a total thickness of about 1.5 mm which dries to about 1.2 mm.) The composition totally encapsulated the VIP.The composition was cured allowed to cure for about 10 minutes in a well ventilated 70°C oven between coats. Post curing was done overnight under the same conditions. The result was a VIP coated on all surfaces / encapsulated in the cured material. The coating provided total fire protection to the underlying VIP and achieved a Euroclass classification of A2 / B, as indicated in Table 4 below. A corresponding VIP without the coating achieves a Euroclass classification of E. The test carried out under BS EN 13823 are set out below in Table 4.

[0093] Table 4

[0094] BS EN 12667: Thermal conductivity

[0095] The cured composition has been shown to have a negligible effect on the thermal performance of VIPs. Initial lambda results average around 4.7 mW / m-K Values are measured according to BS EN 12667.

[0096] An OPTIM-R™ VIP without the composition of the invention has a thermal conductivity of 0.004 W / m-K. With a composition of the invention set out in Table 1 / Table 2 above applied to the VIP to form a VIP coated on all surfaces / encapsulated in the cured material. The composition was applied at a nominal 3kg / m2(equivalent to 1.21.5 mm thickness). Five layers of the composition were applied by brushing, each layer having a thickness of about 300 pm all the way about the VIP. (This gives a total thickness of about 1.5 mm which dries to about 1.2 mm.)

[0097] The composition totally encapsulated the VIP.The composition was cured allowed to cure for about 10 minutes in a well ventilated 70°C oven between coats. Post curing was done overnight under the same conditions. The result was a VIP coated on all surfaces / encapsulated in the cured material. With the composition of the invention applied the initial thermal conductivity of the VIP was 0.0047 W / m-K.

[0098] BS EN 1609: Short term water absorption by partial immersion

[0099] Two VIPs as described above to which a composition given in Table 5 below was applied displayed excellent resistance to water and maintained high strength after partial 24 hour water immersion. The average water absorption value is from 0.03 to 0.04 kg / m2, with all water being desorbed after just 6 hours at room temperature.

[0100] For the preparation of these VIPs, five layers of the composition were applied by brushing each layer having a thickness of about 300 pm all the way about the VIP. This gives a total thickness of 1.2-1.5 mm). The composition totally encapsulated the VIPs. The compositions were allowed to cure for about 10 minutes in a well ventilated 70°C oven between coats. Post curing was done overnight under the same conditions. This resulted in two VIPs coated on all surfaces / encapsulated in the cured compositions.

[0101] Table 5

[0102] BS EN ISO 1182: Non-combustibility test

[0103] Varying samples of cured compositions according to Table 1 with varying amounts of anti-foam agent tested according to BS EN ISO 1182 testing to determine the effect of the amount of anti-foam agent as well as type of fibre used in the composition on its fire performance. As the amount of anti-foam agent was changed the amount of water was changed accordingly so that the total weight percentage in Part A remains 100%. All percentages are percent by weight based on the total weight of the composition Table 6 below indicates the results obtained from this testing. The optimum level of anti-foam agent was found to be about 0.1-0.3% by weight of the total weight of the composition. Moreover, the replacement of organic flax fibre with inorganic ceramic fibre was shown to have a negligible effect on fire performance.

[0104] Table 6

[0105] In addition to the above, Table 7 below provides a comparison of various performance indices of the coated VIP with the composition as set out in Table 1 / Table 2 against VIPs available in the market. The Optim-R™ VIP is available from Kingspan Insulation Limited in the UK.

[0106] Table ?Performance ofA-Class Encapsulated VIP in comparison with Optim-R™

[0107] The words “comprises / comprising" and the words “having / including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0108] It is appreciated that certain features of the invention, which are, for clarity, described inthe context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, forbrevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Claims

Claims1. An aqueous composition comprising an aqueous vehicle and, carried in the aqueous vehicle: a) potassium silicate, wherein the amount of potassium silicate is from about 9% to about 40 % by weight based on the total weight of the composition; b) zinc borate, wherein the amount of zinc borate is from about 1 % to about 10% by weight based on the total weight of the composition; and c) a calcium component, wherein the amount of the calcium component is from about 12 % to about 22 % by weight based on the total weight of the composition.

2. An aqueous composition as claimed in claim 1, wherein the potassium silicate has a silica to potassium ratio of from about 1.25:1 to about 2.5:1.

3. An aqueous composition as claimed in any preceding claim, wherein the amount of potassium silicate is from about 15% to about 40% by weight based on the total weight of the composition.

4. An aqueous composition as claimed in any preceding claim, wherein the amount of potassium silicate is from about 18% to about 29% by weight based on the total weight of the composition.

5. An aqueous composition as claimed in any preceding claim, wherein the amount of zinc borate is from about 2.5 % to about 5%, such as from about 4.0% to about 4.5%, by weight based on the total weight of the composition.

6. An aqueous composition as claimed in any preceding claim, wherein the zinc borate has a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm.

7. An aqueous composition as claimed in any preceding claim, wherein the calcium component is calcium silicate and / or calcium metasilicate optionally wherein the calcium component has a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm.

8. An aqueous solution as claimed in any preceding claim, wherein the calcium component has a mean particle size of less than 50 microns.

9. An aqueous composition as claimed in any preceding claim, wherein the amount of the calcium component is from about 14% to about 20% by weight based on the total weight of the composition.

10. An aqueous composition as claimed in any preceding claim, further comprising a thixotrope, such as bentonite, optionally wherein the amount of the thixotrope is from about 0.1% to about 1.5% by weight based on the total weight of the composition, such as from about 0.5% to about 1% by weight based on the total weight of the composition.

11. An aqueous composition as claimed in claim 10, wherein the amount of the thixotrope is about 0.8% by weight based on the total weight of the composition.

12. An aqueous composition as claimed in any preceding claim, further comprising an anti-foam agent, such as anti-foam mineral oil, optionally wherein the amount of the anti-foam agent is from about 0.1% to about 0.4% by weight based on the total weight of the composition.

13. An aqueous composition as claimed in claim 12, wherein the amount of the anti-foam agent is from about 0.05% to about 0.3% by weight based on the total weight of the composition.

14. An aqueous composition as claimed in any preceding claim, further comprising glass particles, such as glass flakes, optionally wherein the glass particles are present in an amount from about 5% to about 20% by weight based on the total weight of the composition.

15. An aqueous composition as claimed in claim 14, wherein the glass particles include glass particles having a mean particle size from about 105 to about 130 pm, optionally wherein the glass particles are present in an amount from about 2% to about 10% by weight based on the total weight of the composition, such as from about 3% to about 8% by weight based on the total weight of the composition, for example from about 4% to about 6% by weight based on the total weight of the composition.

16. An aqueous composition as claimed in claim 14, wherein the glass particles include glass particles having a mean particle size from about 20 pm to about 40 pm such as from about27 pm to about 32 pm, optionally wherein the glass particles are present in an amount from about 5% to about 12% by weight based on the total weight of the composition such as from about 6% to about 10% by weight based on the total weight of the composition, for example from about 7% to about 9% by weight based on the total weight of the composition.

17. An aqueous composition as claimed in any of Claims 14 to 16, wherein the glass particles include (larger) glass particles having a mean particle size from about 105 to about 130 pm, such as 120 pm and the glass particles include (smaller) glass particles having a mean particle size from about 20 to about 40 pm, such as 30 pm.

18. An aqueous composition of Claim 17, wherein the weight ratio of the larger glass particles to the smaller glass particles is about 1:2.

19. An aqueous composition as claimed in any preceding claim, further comprising of potassium aluminium silicate.

20. An aqueous composition as claimed in claim 19, wherein the potassium aluminium silicate has a mean particle size of less than 50 pm, for example from about 5 pm to about 30 pm, such as from about 10 pm to about 20 pm.

21. An aqueous composition as claimed in claim 19 or 20, wherein the potassium aluminium silicate is in the form of mica, optionally in micronized form, for example muscovite mica, such as micronized muscovite mica.

22. An aqueous composition as claimed any of Claims 19 to 21, wherein the amount of the potassium aluminium silicate is from about 2% to about 8% by weight based on the total weight of the composition, for example from about 4% to about 6% by weight based on the total weight of the composition.

23. An aqueous composition as claimed in any preceding claim, further comprising a toughening / flexibilising agent, optionally in the form of fibres, for example flax or hemp such as flax in the form of flax fibres or hemp in the form of hemp fibres, optionally ceramic fibres, desirably wherein the amount of the toughening / flexibilising agent is from about 0.5% to about 3% by weight based on the total weight of the composition.

24. An aqueous composition as claimed in claim 23, wherein the ceramic and / or flax or hemp fibres have a length from about 1 mm to about 3 mm, such as about 2 mm.

25. An aqueous composition as claimed in any preceding claim, wherein the viscosity of the composition is from about 4000-4500cP.

26. An aqueous composition as claimed in any preceding claim, wherein the composition is a two-part composition.

27. An aqueous composition as claimed in Claim 26 wherein the zinc borate, optionally together with a thixotrope, is present in a different part of the composition than the calcium component.

28. An aqueous composition as claimed in Claim 26 or Claim 27 having a Part A and Part B, wherein Part A includes the potassium silicate, the calcium component, and optionally one or more of: a thixotrope, an anti-foam agent, glass particles, and potassium aluminium silicate, and a toughening / flexibilising agent; and Part B includes the zinc borate, optionally together with a thixotrope.

29. An aqueous composition as claimed in any preceding claim, wherein the pot life of the composition prior to curing is from about 15 minutes to about 60 minutes, such as about 20 to about 60 minutes, for example about 20 minutes.

30. An aqueous composition as claimed in claim 29, wherein the composition is obtained when Part B is added to Part A either at about 6-12% w / w or at a volumetric ratio of Part A to Part B from about 5:1 to about 10:1; optionally from about 8:1 to about 9:1.

31. A process for applying the composition as claimed in claims 1 to 30 onto a substrate, comprising the following steps: a) applying the composition to a surface of the substrate, optionally wherein the composition coats at least a part of the substrate;b) curing the composition optionally by allowing the composition to cure or by exposing the composition to curing conditions such as about 5 to 10 minutes at about 40 to 90°C; c) optionally repeating the above steps on other surfaces of the substrate; and / or d) optionally applying a further amount of the composition to already cured composition; and / or e) optionally repeating step d).

32. The process as claimed in claim 31, wherein the thickness of the cured composition is from about 1 to about 1.5 mm, optionally wherein the thickness of the cured composition is about 0.8 to about 1.3 mm; optionally wherein the composition loses at least 35% by weight based on the total weight of the composition of water.

33. The process as claimed in claims 31 or 32, wherein the substrate on which the composition can be applied includes a thermal insulation product such as a foam body, an insulation panel optionally with an insulating core and one or more metallic skins, a hydrophilic substrate such as an inorganic hydrophilic substrate including silica substrates, an aerogel, a core for a vacuum insulation panel, a vacuum insulation panel, an envelope of a vacuum insulation panel etc.

34. The process as claimed in anyof claims 31 to 33, wherein the substrate is a vacuum insulation panel.

35. A cured composition, for example a coating, obtained by curing the composition as claimed in any of the claims 1 to 30, optionally obtained by a process as claimed in claims 31 to 34.

36. The cured composition as claimed in claim 35, wherein the density of the cured composition, for example a coating, is from about 1200 kg / m3to about 1300 kg / m3.

37. The cured composition as claimed in claim 35 or 36, wherein the cured composition has a resistance to hydrocarbon flame at temperatures from about 1100°C to about 1300°C, such as hydrocarbon flame at a temperature of about 1300°C.

38. The cured composition as claimed in any of claims 35 to 37, wherein the calorific value of the cured composition, is from about 0.6 MJ / kg to about 0.8 MJ / kg as determined according to EN ISO 1716 standards.

39. A substrate, such as an insulation product comprising the composition of any of Claims 1 to 30, the cure product of any of Claims 35 to 38 optionally wherein the composition is in the form of a coating.

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