Composite insulation material

Abstract

The present invention relates to a composite insulation material comprising polyimide and polyethylene foam layers, the use of such composite insulation material, an insulated entity comprising said composite insulation material and a method for insulating a surface with said composite insulation material.

Description

[0001] COMPOSITE INSULATION MATERIAL

[0002] The present invention relates to a composite insulation material comprising polyimide and polyethylene foam layers, the use of such composite insulation material, an insulated entity comprising said composite insulation material and a method for insulating a surface with said composite insulation material .

[0003] Background

[0004] The present invention aims to improve thermal insulation materials . In thermal insulation, foams are often used .

[0005] Various foams may be used and selected on the basis of the desired properties .

[0006] Selection criteria in this regard may include thermal and acoustic insulation values, mechanical strength, nontoxicity, fire resistance and resistance to water absorption and water vapour permeation. An additional, but important consideration are the costs of the material .

[0007] It is a challenge to find a foam based insulation material that has a good balance of these properties .

[0008] Therefore, there is a need for insulation materials which provide a good balance of these properties .

[0009] US 2017 / 0210092 Al discloses insulating structures that filter aerogel dust from cracked or damaged aerogel within a scaffold, slowing or preventing loss of dust from the insulating structures .

[0010] Summary of the invention

[0011] In order to accommodate this need, the present invention relates in a first aspect to a composite insulation material comprising a layered combination of at least one layer of polyimide (PI ) foam and at least one layer of polyethylene (PE) foam. In a second aspect, the invention relates to the use of the composite insulation material according to the first aspect of the invention for thermal insulation.

[0012] In a third aspect the invention relates to an insulated entity, comprising the composite insulation material according to the first aspect .

[0013] In a fourth aspect the invention relates to a method for insulating a surface, comprising attaching the composite insulation material of the first aspect to said surface .

[0014] Description of the drawings

[0015] Figure 1 shows different embodiments of the composite material of the present invention. The bottom of each embodiment ( I ) , ( II ) , ( HI ) and ( IV) represents the surface facing the entity that is least partially covered by the composite insulation material . The top represents the surface facing away from said entity.

[0016] Detailed description of the invention

[0017] The inventors have found that the use of a composite insulation material comprising a combination of polyimide (PI ) foam and polyethylene (PE) foam layers results in an insulation material having excellent acoustic and thermal insulating properties in combination with favourable physico-mechanical properties and superior amphiphilic behaviour at relatively low costs . The composite insulation material according to the invention provides a good balance of favourable thermal and acoustic insulation values, mechanical strength, non-toxicity, fire resistance and resistance to water absorption and water vapour permeation and costs of the material .

[0018] In accordance with the above, the composite material according to the invention comprises a layered combination of at least one layer of polyimide (PI ) foam and at least one layer of polyethylene (PE) foam.

[0019] The polyimide (abbreviated as PI ) in the context of the present invention is a polymer compound with an imide ring bond in its molecular chain. It is prepared by the reaction between a dianhydride and a diamine (as represented in scheme 1, in which "R" can be an aromatic ring in aromatic polyimides) , but can also be prepared by the reaction between a dianhydride and a diisocyanate .

[0020] Scheme 1

[0021]

[0022] Common dianhydrides used for preparation of polyimide include pyromellitic dianhydride, benzoquinonetetracarboxylic dianhydride and naphthalene tetracarboxylic dianhydride . Diamines that are commonly used include 4 , 4 ' -diaminodiphenyl ether (DAPE) , metaphenylenediamine (MDA) and 3 , 3 ' -diaminodiphenylmethane .

[0023] Physical properties as well as processing properties of the polyimide product formed in the reaction of the dianhydride and diamine may be tuned by selection of the appropriate starting reagents .

[0024] Typically, polyimide has a high glass transition temperature of 240°C< TG > 300°C . It has high softening temperatures and a very high thermal stability, and is able to withstand long term operating temperatures of 200°C < Tg> 300°C with short term peaks of up to 400°C . It is highly chemically resistant, and can resist a broad spectrum of solvents, acids, and bases . It has superior electrical insulation properties, having a dielectric constant of 4.0 under 103Hz, and a dielectric loss of only 0 . 004~0 . 007 , due to which polyimides are extensively used in electronic applications . Its flame resistance is 100% and unlike many plastics, polyimides are naturally flame resistant, so it does not require additives like flame-retardants . Furthermore, PI is inherently halogen free . PI foam is the only organic foam which is classified as non-combustible . It is able to withstand a continuous temperature range of <205°C, with peak temperatures of up to 300°C . Calcination may occur at temperatures above 205°C .

[0025] Usually, PI foam has a substantially open-cell structure . A substantially open-cell structured foam in the context of the present invention refers to a foam with a 70% open cell structure or even higher, such as foams with very low percentages of closed cells (< 10%) , or, in other words, percentages of open cells of 90 % or more . However, it is feasible to obtain PI foam having substantially a closed cell structure, such as a 70% closed cell structure .

[0026] An open-cell structure means that cells of the foam are not completely encapsulated. In other words, the cells are left open. Closed cells are cells that are, as the name suggests, completely closed. The percentages of open cells or closed cells with regard to the total number of cells can be determined in various ways common in the art for foams . One exemplary and preferred way is by visual inspection of the foam, so that the percentages of open and / or closed cells may suitably represent the percentages as determined by visual inspection. Said visual inspection preferably involves the use of a magnifying means such as a microscope with the possible assistance of a computer program for automated determination and calculation of the numbers and percentages of open and closed cells . An alternative or supplemental approach may be by measuring water absorption with methods according to NEN-EN 1609 or ASTM C209 standards, which are based on determination of water absorption by the foam. A high closed cell content usually reduces the water absorption. Hence the water absorption may be an indicator of the open or closed cell content . In these methods the cells are counted and the percentage water absorption provides a value which can be used to calculate the percentage of open and / or closed cells .

[0027] A substantially closed-cell structured foam in the context of the present invention refers to a foam with a 70% closed cell structure or even higher, such as foams with very low percentages of open cells (< 10%) , or, in other words, percentages of closed cells of 90 % or more .

[0028] Preferably, the PI foam in the composite insulation material of the invention has a substantially open-cell structure, which contributes to the acoustic properties of the foam. Alternatively, the PI foam may have a substantially closed cell form, which prevents water ingress .

[0029] Suitable PI foams that are preferred in the context of the present invention may have a water vapour diffusion resistance factor (p) of 1.000 <p <8.236 or higher . The vapour diffusion resistance is a dimensionless figure that indicates the ability for water to travel through the material, it may be determined on basis of the method described in EN-13469. A greater number indicates a greater resistance towards water vapour to pass through.

[0030] Preferably, a PI foam in the context of the present invention has a lambda value of 0.030-0.060 W / m -K at 40°C, preferably of 0.035-0.050 W / m -K at 40°C . The lambda value, also commonly referred to as 'K-value' or 'X-value' , is an indicator of the thermal conductivity of a product, in the context of the present invention, a foam, in units of W / m -K. The lower the lambda value is, the better thermal insulation is . The lambda value may be determined according to EN 12667, EN 12664, ASTM C518 or ASTM C534. Suitable PI foams may for instance have a lambda of 0.046 W / m -K at 24 °C Preferably, PI foams in the context of the present invention have a density of 5-50 kg / m3, more preferably of 8-32 kg / m3.

[0031] Preferably, the PI foam in the context of the present invention has a non-flaming Smoke Developed Index (SDI ) of 3 or lower measured according to ASTM E662.

[0032] Preferably, the PI foam in the context of the present invention has a Noise Reduction coefficient (NRC) between 0. 60 and 1.00, more preferably between 0.70 and 0.80, such as 0.75, measured according to ASTM C423 and E795, Mounting A. The Noise Reduction coefficient (NRC) describes a material' s ability to absorption of sound. Open cell structures contribute towards sound absorption.

[0033] Properties of a particularly suitable PI foam material in the context of the invention are shown in table 2 of the examples section.

[0034] An exemplary PI foam having the abovementioned preferred characteristics and which is very suitable for purposes of the present invention includes the commercially available Solimide CC-306, as manufactured by Boyd Co . This material is lightweight, non-wicking, has a fire resistance exceeding FAR 25.856 specifications, has minimal smoke generation characteristics, is heat and pressure formable, is flexible and stable at cryogenic temperatures, is hydrolytically stable, non-toxic and formaldehyde free, has low off-gassing, and does not support microbial growth.

[0035] The other main component of the composite insulation material of the present invention is polyethylene (PE) foam.

[0036] Polyethylene (PE) foam is composed substantially of the thermoplastic polymer polyethylene, preferably low density polyethylene, and may further contain other polyolefin elastomers (POEs) . Such foams are referred to in the art as low density polyethylene based polyolefin elastomer foams . This type of foam is usually produced using physical blowing agents ( for instance iso-butane) .

[0037] This type of foam has good product properties such as insulation value, fire behaviour, water vapour transmission and water absorption capacity. PE foam may be produced by a direct extrusion process . As a foaming agent, for instance isobutane gas can be used. After extrusion the foam may be coiled directly.

[0038] A PE foam in the context of the present invention preferably has a lambda value of 0.030-0.060 W / m -K at 40°C, more preferably of 0.040-0.050 W / m -K at 40°C .

[0039] In one preferred embodiment the PE foam does not contain flame retardant material, because the use of such, often halogen based, flame retardant material has become superfluous due to the excellent flame resistance of the composite material of the invention. As a result the full composite material may be halogen free .

[0040] PE foam is preferably substantially in closed-cell form, for instance 80% closed cell . Water ingress may be limited due to its closed cell structure . Herein the term "closed-cell" has the same meaning as explained above for PI foam.

[0041] Preferably, PE foams have a density of 10-60 kg / m3, more preferably of 18-40 kg / m3.

[0042] Properties of a particularly suitable PE foam material in the context of the invention are shown in table 1 in the examples section.

[0043] In the context of the present invention, the PE foam may be a polyolefin thermal insulation foam as defined in WO 02 / 42679 Al or as defined in WO 2019 / 05402 Al by the present applicant .

[0044] For purposes of the invention, particularly preferred PE foams have properties such as those of the commercially available PE foam ThermaSmart PRO LS HF, as manufactured by the present applicant . Such PE foam is characterized by low thermal conductivity ( 0.038 W / m -K at 40°C and 0.036 W / m -K at 20°C tested according to EN 12667 ) , has very good fire resistance of CsldO when it does not contain flame retardants and BLsld0 and BsldO, as measured according to EN 13501-1 when it contains flame retardants . The PE for purposes of the present invention suitably has service temperatures between -120 up to +105°C or even broader ranges, has very low water absorption (WS005 i . e. lower than 0.05 kg / m2) , has a compression strength range of 10-350 kPa and has low combustibility. It suitably shows first signs of softening around 100°C and has a melting point of ca .

[0045] 105°C, and a water vapour diffusion resistance factor (p) of 8, 000-25, 000, preferably 12, 000-23, 000 as determined by EN-13469. It has a high water absorption resistance capacity of < 2% as measured according to NEN-EN 1609 or NEN-EN 13472. In the context of the present invention the composite insulation material may comprise one or multiple layers of PI foam and one or multiple layers of PE foam, stacked together to form a multilayered laminated structure .

[0046] The PI and PE foam layers are suitably present in the composite insulation material of the invention as the principal isolating material of the composite insulation material . The composite insulation material of the invention in this respect therefore is suitably essentially free or completely free of other insulation materials than the PI and PE foam layers . In particular, in a suitable embodiment the composite insulation material of the invention is free of aerogel material .

[0047] Apart from the PI foam layer (s) and PE foam layer (s) the composite insulation material may contain further layers of other materials .

[0048] Such additional layers may include, without limitation, an outer protective coating on one or both of the top and bottom surfaces of the material .

[0049] Additional layers may also include any intermediate layer or layers between PI foam and PE foam layers .

[0050] In a preferred embodiment said protective coating is provided on the outer surface of said PI foam. Such a protective coating may suitably be an aluminium cladding.

[0051] For many applications of the composite insulation material of the invention, it may be preferable that the PI foam is provided with aluminium cladding on the outer surface of the PI foam for protection of the integrity of said PI foam, however due to the high strength of the PE foam, aluminium cladding is not required for additional strength. Aluminium cladding may however still be employed on the PI foam layer to protect the foam layer from water ingress . Apart from aluminium cladding, the composite insulation sheet may contain additional layers of material or more components except for the above-mentioned layers and components, such as coatings, adhesives, fixating films or foils and the like .

[0052] In a practical and suitable embodiment, the composite material further comprises an intermediate layer of flexible material between said at least one layer of PI foam and said at least one layer of PE foam. The term flexible in the context of the invention is regarded as the ability of a material to be bent of flexed without macrostructural failure . The material for instance is capable of bending at least 5° , at least 25° , at least 45° , at least 65° , at least 85° , or at least 90° without macroscopic failure . Such a flexible layer enhances the acoustic properties of the composite material, so that it may be used for simultaneous thermal insulation and acoustic insulation of a surface . Such a layer may suitably be a foil or any other sheetlike structure, or even an adhesive layer or intermediate coating .

[0053] In preferred embodiment therefore, the composite insulation material of the invention consists of a layer of PI foam; a layer of PE foam; at least one intermediate layer between said layer of PI foam and said layer of PE foam, and optionally one or more outer layers on the side of the PE foam and / or PI foam.

[0054] In the composite material of this embodiment, the PI foam layer absorbs sound, the intermediate layer blocks sound, and the PE layer may block and / or reflect sound. Figure 1 ( IV) shows a composite material comprising such an intermediate layer .

[0055] The material for such intermediate layer must have sufficient weight and have a sufficient material density for acoustic blocking. A hard dense surface will cause reflection of the sound. A particularly suitable material for such intermediate layer with these desired properties is ethylene propylene diene monomer (EPDM) rubber .

[0056] In a preferred embodiment the layers of the composite insulation material of the invention are fixed to each other, suitably by glueing.

[0057] In a basic, but suitable embodiment the composite insulation material comprises a layer of PI foam directly adj acent to a layer of PE foam. In this case it is preferred that said directly adj acent layers of PI foam and PE foam are glued to each other . Figure 1 ( I ) and ( II ) show such a basic material .

[0058] In a suitable and practical embodiment the composite insulation material consists of a layer of PI foam and a layer of PE foam glued together, optionally provided with one or more outer layers of other material on one or both of the outer surfaces .

[0059] In accordance, the composite insulation material consists of a layer of PI foam and a layer of PE foam glued together, optionally provided with a protective coating on one or both of the outer surfaces, for instance wherein said protective coating is an aluminium cladding forming the outer surface of the insulation material on at least the PI foam side thereof . Figure 1 ( III ) shows such a composite material with an external layer of cladding.

[0060] Adhesives for the purpose of gluing in the context of the composite insulation material of the invention are known in the art . This way, a flexible composite insulation material is formed. The thermal effectiveness of the composite material remains intact due to comparable heat insulation values (X) of the respective PI and PE foams . In the context of the present invention, the composite insulation material may have a combined lambda value of 0.030-0.060 W / m -K at 40°C, more preferably of 0.040-0.050 W / m -K at 40°C .

[0061] The composite insulation material in the context of the invention may be in the form of a foam sheet or hollow profile . A hollow profile may for instance have a tubular shape and is suitable for insulating cylindrical structures, such as pipes . Sheets of the composite material are particularly useful for insulation of large surfaces .

[0062] The thickness of the respective PI and PE layer may be suitably selected depending on the final application and requirements towards physical properties .

[0063] Said layers may have any desired thickness, which may depend on the specific application or on the availability of the individual foams . Suitable PI foams are commercially available in a thickness of 4-250 mm, in particular 6-200 mm. Suitable PE foams are commercially available having a thickness of for instance 7.5, 10, 13, 19, 25 mm.

[0064] A thickness ratio of the layers may be between 5 : 1 (PI / PE) to 1 : 5 (PI / PE) , between 3 : 1 (PI / PE) to 1 : 3 (PI / PE) , between 2.5 : 1 (PI / PE) to 1 : 2.5 (PI / PE) , between 2 : 1 (PI / PE) to 2 : 5 (PI / PE) , between 1.5 : 1 (PI / PE) to 1 : 5 (PI / PE) or be 1 : 1 (PI / PE) . For instance, the thickness ratio may be 25mm: 25mm (PI / PE) , 10mm: 25mm (PI / PE) , or 10mm: 10mm (PI / PE) .

[0065] The composite material may be used in such a configuration that a PE layer thereof faces the surface of an entity, such as equipment or space, to be insulated and the PI layer faces the side that is directly exposed to heat / and or flames . Such an embodiment is shown for instance schematically in Figure 1, ( I ) , ( III ) and ( IV) . This way the PE foam layer is less exposed to this heat by insulation by the PI layer, allowing to optimally exploit the excellent fire resistance properties of the PI foam. It also allows the use of PE without halogen containing flame retardants because the PE is effectively protected from fire by the incombustible PI foam layer . As an example of this configuration, the composite insulation material may be arranged around a pipe such that a PE layer forms an inner layer and the PI layer forms an outer layer . This embodiment would be very suitable if the environment surrounding said pipe would be very hot and the contents of the pipe need to be protected from this heat . In this configuration, the thickness of the PI foam layer should be selected such that it is able to keep the temperature of the PE foam below 92 °C, so it does not reach the maximal service temperature of PE foam. This configuration enables naval applications, in which the temperature of the insulated surface is required to stay intact for 15 minutes at 200°C .

[0066] Alternatively, the composite material may be used in such a configuration that a PI layer thereof faces the hot surface of an entity, such as equipment or space, and the PE layer faces the side to be protected from the heat . Such an embodiment is shown for instance schematically in Figure 1, ( II ) . Also this way the PE foam layer is less exposed to this heat by insulation by the PI layer . As a further advantage of this embodiment, the PI layer is protected by the PE layer against mechanical impact from its surroundings and from water ingress . As an example of this configuration, the composite insulation material may be arranged around a pipe such that said PI layer forms an inner layer . This embodiment would be very suitable if the inside of said pipe is hot and the surroundings need to be protected from this heat . This configuration ensures excellent fire protection, thermal resistance and good acoustic properties . Also, this configuration enables insulation of surfaces that have a temperature of up to 205°C and / or that may have short temperature peaks of up to 300°C

[0067] In other words, the composite material may be optimally exploited in configurations in which the PI layer thereof faces heat / and or flames . The optimal configuration may as such be selected depending on whether the heat and / or flames to be protected from comes from the surroundings or from the surface of the entity to be insulated.

[0068] As mentioned above the invention also relates to an insulated entity, comprising the composite insulation material according to the invention. The composite insulation material in this regard at least partially covers the entity to be insulated.

[0069] In an embodiment the composite insulation material is arranged on the entity such that a said PI layer forms an inner layer with respect to a said PE layer . In accordance with the explanations above, this embodiment is in particular suitable in case the entity is hot, such as a pipe transporting hot fluids .

[0070] In another embodiment the composite insulation material is arranged on the entity such the composite insulation material is arranged such that a said PE layer forms an inner layer with respect to a said PI layer . In accordance with the explanations above, this embodiment is in particular suitable in case the surroundings of the entity are hot relative to the entity itself .

[0071] In a particularly preferred embodiment, the composite insulation material is used to insulate a pipe . In accordance, the entity of the invention may be a pipe . The acoustic properties of the PI foam layer enable absorption of sound to dampen noise in pipes, for instance air ducts and water pipes .

[0072] Apart from the composite insulation material of the invention the entity may further be provided with an outer casing, either as separate casing or as part of the insulation material itself .

[0073] For instance, an insulated pipe may suitably comprise an outer casing. The outer casing may be of the same material as the pipe and may suitably be a plastic or metal casing. The outer casing may be a smooth film or an outer pipe, for instance a plastic outer pipe . It is preferred that said outer casing is a corrugated outer casing. Such a corrugated or ribbed casing has ribs extending over the circumference of the casing, which improves flexibility of the insulated pipe, while at the same time providing additional strength and thus protection from the environment surrounding it .

[0074] An insulated pipe in the context of the invention may substantially be realised for instance as described in WO 02 / 31400 Al of the present applicant, wherein the composite insulation material of the present invention is used as insulation material to insulate said pipe .

[0075] Any other entities may be insulated with the composite insulation material of the invention. Such entities may include without limitation any entity for use in any of the applications selected from HVAC applications, transport applications, marine applications, navy applications, or an entity selected from electronic instruments, medical instruments and analytical instruments .

[0076] In accordance with the invention any surface of any entity may be insulated by attaching the composite insulation material to said surface, particularly such that at least part of said surface or even the complete surface is covered with the insulation material . This may include any suitable ways of attaching the material and in a practical embodiment the insulation material may be glued on or wrapped around the entity to be insulated.

[0077] In case the entity is a pipe, the surface in this regard is the surface of a pipe . In case of other applications, the surface may, without limitation, be a surface in any of the applications selected from HVAC applications, transport applications, marine applications, navy applications, sensitive electronic instruments, medical instruments and analytical instruments .

[0078] The composite material in the context of the invention is particularly suitable to deal with the insulation challenges faced in insulating cooling and heating systems (like HVAC equipment, piping systems, etc . ) and / or surfaces exposed to harsh ambient conditions in terms of high humidity and / or temperature fluctuations . The composite insulation material and insulated pipes according to the invention may therefore be used for various thermal insulation applications, such as hot water conduits, high and low pressure steam pipes, and pipes for split-air conditioning, district heating, solar energy exploitation, marine applications and the process industry.

[0079] The composite insulation material is particularly suitable for application in heating, ventilation, air-conditioning (HVAC) applications . By insulating HVAC systems with the composite insulation material according to the invention, excellent fire behaviour characteristics of the systems can be achieved. Such HVAC systems may be present in buildings, maritime transport and in industry.

[0080] The composite material is also particularly suited in applications where PI foams are generally employed, such as transport applications, including space vehicles, aircraft cabins, and land and sea transport among other applications wherein human life or equipment require protection against overheating of other insulation materials that are flammable or smoke-emitting.

[0081] Such applications include, but are not limited to, navy applications such as in submarines, aircraft carriers, cruisers, destroyers, frigates, minehunters, patrol vessels; and commercial marine applications, such as high speed yachts and ferries . Marine applications include but are not limited to use in hull linings, bulkheads and deckheads, ceiling panels, hangar decks, beam and duct wraps and HVAC applications .

[0082] Further applications include but are not limited to military armoured vehicles, personnel carriers, railway cars and passenger locomotives, aircrafts, mining vehicles, automotive engine bays, cabin and cavity linings, high temperature environments, such as insulation in ovens, ducting, duct and piping insulation. Furthermore, low outgassing properties makes the product an ideal choice for use in sensitive electronic, medical and analytical instruments .

[0083] In marine applications it is very important to have materials possessing good thermal properties, good acoustic performance, which are able to withstand humidity and water (especially salt water) , which are lightweight, nonflammable, and non-fibrous . The composite material according to the invention is therefore very suitable for use in the navy to insulate maritime equipment comprising insulation panels or pipes, specifically ships, ship hulls, and submarines .

[0084] Especially for the purpose of naval applications next to the thermal insulation capabilities, the acoustic capabilities are important . With the above-mentioned invention, the inventors have found a solution with a good insulation performance, favourable physico-mechanical properties and superior amphiphilic behaviour at a favourable cost level . Therefore, the composite insulation material described herein is able to serve as an improved alternative to the presently employed stone wool for insulation of ship hulls and piping systems, and the presently employed EPDM foam and PE foam insulation for air conditioning ducts in naval equipment .

[0085] Examples

[0086] The following examples are meant to illustrate the invention and not to limit the claims .

[0087] Table 1 and 2 show physical properties of particularly suitable PI foam and particularly suitable PE foam respectively.

[0088] Table 1 : Properties of PE foam used (ThermaSmart PRO LS HF)

[0089] <

[0090]

[0091] Table 2 : properties of PI foam used (Solimide CC-306) <

[0092] <

[0093]

[0094] * Subj ect to normal manufacturing variation

[0095] A composite material consisting of a 25 mm thick PI foam layer and a 25 mm thick PE foam layer having properties of table 1 and 2 respectively was subj ected to thermal conductivity tests according to EN ISO 12667 : 2002 , and water absorption tests according to EN ISO 29767 : 2019- 08 . Both configurations wherein the PI foam layer and the PE foam layer facing the testing conditions are tested . Results are shown in table 3 .

[0096] Table 3 : Thermal conductivity tests according to EN ISO 12667 : 2002 and water absorption according to EN ISO 29767 : 2019-08 .

[0097]

[0098] As shown in thermal conductivity tests according to EN ISO 12667 : 2002, measured at 40°C, (W / m -K) , the composite material has a lambda value of 0.0424 W / m -K when the PE foam layer is exposed to the hot plate apparatus of the test, and the PI foam layer is exposed to the environment .

[0099] The composite material has a lambda value of 0.0433 W / m -K when the PI foam layer is exposed to the hot plate apparatus of the test, and the PE foam layer is exposed to the environment .

[0100] These results show that the insulation properties of the PI foam and PE foam are maintained in the composite material .

[0101] The composite material has a water absorption according to EN ISO 29767 : 2019-08 of 0.07 g / m2(WS 01 ) when the PE layer is exposed to partial immersion conditions of the test, and the PI layer is exposed to the environment .

[0102] The composite material has a water absorption according to EN ISO 29767 : 2019-08 of 0.38 g / m2(WS 05) when the PI layer is exposed to partial immersion conditions of the test and the PE layer is exposed to the environment . These results show that the PE foam layer protects the PI foam layer from water .

Claims

CLAIMS1. Composite insulation material, comprising a layered combination of at least one layer of polyimide (PI ) foam and at least one layer of polyethylene (PE) foam.

2. Composite insulation material according to claim 1, comprising a said layer of PI foam directly adj acent to a said layer of PE foam.

3. Composite insulation material according to claim 1, comprising at least one intermediate layer between said at least one layer of PI foam and said at least one layer of PE foam.

4. Composite insulation material according to claim 3, which consists ofa layer of PI foam;a layer of PE foam;at least one intermediate layer between said layer of PI foam and said layer of PE foam, andoptionally one or more outer layers on the side of the PE foam and / or PI foam.

5. Composite insulation material according to claim 3 or 4, wherein said intermediate layer is a flexible material .

6. Composite insulation material according to claim 5, wherein said flexible material is composed of EPDM rubber .

7. Composite insulation material according to any of the previous claim, wherein said layers are glued together .

8. Composite insulation material according to any of the previous claims, comprising an outer protective coating on one or both of its top and bottom surfaces .

9. Composite insulation material according to claim 8, wherein said protective coating is provided on the outer surface of said PI foam.

10. Composite insulation material according to claim 9, wherein said protective coating is an aluminium cladding.

11. Composite insulation material according to any of the previous claims, wherein said PE foam has a percentage of closed cells of 70 % or more .

12. Composite insulation material according to any of the previous claims, wherein said PI foam has a percentage of open cells of 70 % or more .

13. Composite insulation material according to any of the previous claims, wherein said PI foam and / or said PE foam have a lambda value of 0.030-0.060 W / m -K at 40°C, preferably of 0.035-0.050 W / m -K at 40°C, determined according to EN 12667, EN 12664, ASTM C518 or ASTM C53414. Composite insulation material according to any of the previous claims, wherein said PI foam layer has a nonflaming Smoke Developed Index (SDI ) of 3 or lower measured according to ASTM E662.

15. Composite insulation material according to any of the previous claims, wherein the PI foam layer has a Noise Reduction Coefficient (NRC) for 25 mm between 0. 60 and 1.00, more preferably between 0.70 and 0.80, wherein the Noise Reduction Coefficient is measured according to ASTM C423 and E795, Mounting A.

16. Composite insulation material according to any of the previous claims, wherein a thickness ratio of PI : PE layers is 1 : 1 to 2.5 : 1.

17. Composite insulation material according to any of the previous claims, wherein said composite insulation material is in the form of a foam sheet or hollow profile .

18. Use of the composite insulation material according to any of the previous claims for thermal insulation.

19. Use according to claim 18, wherein said thermal insulation is for insulation of a surface in any of the applications selected from HVAC applications, transport applications, marine applications, navy applications, sensitive electronic instruments, medical instruments and analytical instruments .

20. Insulated entity, comprising the composite insulation material according to any of the claims 1-17.

21. Insulated entity according to claim 20, wherein the composite insulation material is arranged such that a said PI layer forms an inner layer with respect to a said PE layer .

22. Insulated entity according to claim 20, wherein the composite insulation material is arranged such that a said PE layer forms an inner layer with respect to a said PI layer .

23. Insulated entity according to any of the claims 20 to 22, further comprising an outer casing.

24. Insulated entity according to any of the claims 20 to 23, wherein the entity is a pipe .

25. Insulated entity according to any of the claims 20 to 24, wherein said entity is an entity for use in any of the applications selected from HVAC applications, transport applications, marine applications, navy applications, or an entity selected from electronic instruments, medical instruments and analytical instruments .

26. Method for insulating a surface, comprising attaching the composite insulation material of any of claims 1-17 to said surface .

27. Method according to claim 26, wherein the surface is the surface of a pipe .

28. Method according to claim 26 or 27 wherein the surface is a surface in any of the applications selected from HVAC applications, transport applications, marine applications, navy applications, sensitive electronic instruments, medical instruments and analytical instruments .-o-o-o-

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