WO2014118741A1

WO2014118741A1 - Thermal insulation plate

Info

Publication number: WO2014118741A1
Application number: PCT/IB2014/058702
Authority: WO
Inventors: Peter Farkas Binderup Hansen; Dorte Bartnik JOHANSSON
Original assignee: Rockwool International A/S
Priority date: 2013-01-31
Filing date: 2014-01-31
Publication date: 2014-08-07
Also published as: WO2014118741A8

Abstract

The invention relates to a thermal insulation plate comprising: a vacuum insulation panel having a first major face, a second major face and side edges joining the first and second major faces; and protecting covers, each formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man- made vitreous fibres present in the foam composite material have a length of less than 100 micrometers; wherein the protecting covers are affixed to the vacuum insulation panel so as to cover substantially the entire first major face and substantially the entire second major face of the vacuum insulation panel.

Description

Thermal Insulation Plate

Field of the Invention The present invention relates to a thermal insulation plate comprising a vacuum insulation panel. This type of thermal insulation plate is usually used for insulating structures where a very high degree of insulation is required or where space is at a premium. The present invention also relates to a thermally insulated structure and a method for constructing such a structure.

Background to the Invention Insulation of buildings is often provided by conventional insulating materials such as man-made vitreous fibre products and foam products. Such products are generally economical to produce and provide good levels of insulation, and, in the case of man-made vitreous fibre products, provide a high level of fire resistance. Nevertheless, some applications require either a higher level of thermal insulation than can be provided by such conventional products or require a thinner layer of insulation, or a combination of both. In such cases, vacuum insulation panels (VIPs) can be used. VIPs can exhibit a thermal conductivity of from 0.004 w/m.k to 0.010 w/m.k. Vacuum insulation panels comprise a porous core material that acts a support structure for the vacuum insulation panel and an air-tight shell that prevents ingress of gas into the vacuum insulation panel. Such VIPs, however, can be quite delicate and are susceptible to damage when they are handled in storage, during transport and during installation. If the airtight shell is pierced, then the insulating properties of the VIP are seriously compromised. Furthermore, generally, vacuum insulation panels cannot be cut to a desired size, because the vacuum would not survive any damage to the shell.

In order to protect the surfaces of vacuum insulation panels, sandwich-type constructions with protective layers made from foam are known, as in WO2007/097686, for example. However, there remains a problem that, in spite of the protective foam, the vacuum insulation panel can still be damaged. Furthermore, the use of foam can result in a lower fire resistance class being achieved.

Summary of the Invention

In order to solve the above-mentioned problems, the invention provides a thermal insulation plate comprising:

a vacuum insulation panel having a first major face, a second major face and side edges joining the first and second major faces; and

protecting covers, each formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man- made vitreous fibres present in the foam composite material have a length of less than 100 micrometers;

wherein the protecting covers are affixed to the vacuum insulation panel so as to cover substantially the entire first major face and substantially the entire second major face of the vacuum insulation panel.

The invention also provides a thermally insulated structure comprising a surface and a plurality of adjacent thermal insulation plates of the invention disposed on the surface, wherein the thermal insulation plates preferably abut each other. The invention also provides a method for constructing a thermally insulated structure comprising a surface and a plurality of adjacent thermal insulation plates of the invention, wherein the method comprises positioning and fastening the thermal insulation plates on the surface. The thermal insulation plate of the invention has excellent thermal insulation properties, which are enhanced by the protecting covers. The particular foam composite material that is used can include a relatively high level of man-made vitreous fibres, which allows it to have good fire resistance, good compressive strength and resistance to compression. The high level of resistance to compression in particular allows the protecting covers to provide an improved level of protection for the vacuum insulation cover, minimising the risk of damage and loss of vacuum in the panel. Detailed Description of the Invention

The dimensions of the thermal insulation plate are not limited and vary depending on the area to be insulated and the level of insulation required. Generally, the thermal insulation plate has an area of from 200cm² to 3m², preferably 500cm² to 1 .5m², more preferably 1000cm² to 1 m², most preferably from 2000cm² to 8000cm². Usually, the thermal insulation plate has a thickness in the range 15 to 100mm, preferably from 20 to 80mm, more preferably 25 to 70mm. The thermal insulation plate can be any shape, depending on the shape of the surface to be insulated, but generally it is square or rectangular.

The thermal insulation plate of the invention comprises a vacuum insulation panel having a first major face, a second major face and side edges joining the first and second major faces. The vacuum insulation panel is of a type known in the art. It comprises a porous core material that acts a support structure for the vacuum insulation panel and an air-tight shell that prevents ingress of gas into the vacuum insulation panel. The porous core material has open pores so as to allow the air to be extracted from them during manufacture of the vacuum insulation panel. Suitable porous core materials include materials comprising fumed silica, and optionally also opacifier and glass fibres, e.g. 3-4 wt % glass fibres, 12 wt % opacifier and the remainder fumed silica.

There is no particular limitation on the dimensions of the vacuum insulation panel. Generally the dimensions vary depending on the area to be insulated and the level of insulation required. The extent of the vacuum insulation panel within the thermal insulation plate also depends on the degree to which cutting of the edges of the plate might be desired. Generally, the vacuum insulation panel has an area of from 200cm² to 3m², preferably 500cm² to 1 .5m², more preferably 1000cm² to 1 m², most preferably from 2000cm² to 8000cm². Usually, the vacuum insulation panel has a thickness in the range 10 to 50mm, preferably from 10 to 40mm, more preferably 10 to 30mm. The vacuum insulation panel can be any shape, depending on the shape of the surface to be insulated, but generally it is square or rectangular. The protecting covers are each formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometers. The protecting covers may be affixed to the vacuum insulation panel by any suitable means that does not damage the vacuum insulating panel, in particular by piercing the shell of the panel. For example, the protecting covers can be attached by adhesive or a bond may formed between the protecting covers and the vacuum insulation panel during formation of the polymeric foam composite material such that no extrinsic fixing means is required.

The protecting covers are affixed to the vacuum insulation panel so as to cover substantially the entire first major face and substantially the entire second major face of the vacuum insulation panel. In order to protect the vacuum insulation panel from being pierced effectively, there is essentially no part of either the first major face or the second major face that is exposed. The protecting covers can have dimensions greater than those of the vacuum insulation panel, so as to overhang the edges of the vacuum insulation panel, but their dimensions may not be smaller.

The protecting covers can be affixed to the vacuum insulation panel by any means. For example, adhesive can be used to bond the protecting covers to the vacuum insulation panel. Alternatively, an intrinsic bond could be formed if the polymeric foam composite material is formed in situ on the surface of the vacuum insulation panel.

In a preferred embodiment a further protecting cover is affixed to the vacuum insulation panel so as to cover at least one side edge of the vacuum insulation panel substantially completely. Preferably, the further protecting cover is formed from the polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometres. The further protecting cover can be formed separately from the protecting covers that cover the major faces of the vacuum insulating cover. Alternatively, the all of the protecting covers can be formed from the same piece of polymeric foam composite material. The protecting covers on the major faces of the vacuum insulation panel are formed from the polymeric foam composite material described below. Generally, the protecting covers have a thickness from 3mm to 20mm, although thicknesses outside this range can be used if desired. The thickness of each protecting cover need not be the same, e.g. the protecting cover may be relatively thin on one face adapted for facing a wall, and relatively thick on the opposing face.

Further protecting covers can be affixed to the vacuum insulation panel so as to cover every side edge of the vacuum insulation panel substantially completely, each protecting cover being formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man- made vitreous fibres present in the foam composite material have a length of less than 100 micrometres. In a particularly preferred embodiment, all of the protecting covers are formed from a single piece of polymeric foam composite material, so that the vacuum insulation panel is completely encased in polymeric foam composite material. Forming the thermal insulation panel in this way allows complete protection of the vacuum insulation panel with no gaps between the protecting covers.

The protecting covers that cover the side edges of the vacuum insulation panel not only protect the vacuum insulation panel from damage, but also provide an area at the side edge of the thermal insulation plate that can be cut so as to adjust the size of plate. Therefore the further protecting cover or covers preferably extend from the side edge of the vacuum insulation panel by a distance of from 20 to 150mm, preferably from 30 to 100mm, more preferably from 30 to 50mm. This allows a high level of adjustment to be made in the size of the thermal insulation plate, whilst still ensuring that the vacuum insulation panels cover a high percentage of the surface being insulated.

Usually, the protecting covers on the first and second major faces of the vacuum insulation panel overhang the vacuum insulation panel by the same distance as the distance by which the side protecting panels extend from the side of the vacuum insulation panel. When the protecting covers on the first and second major faces of the vacuum insulation panel overhang the vacuum insulation panel, it is preferred that at least one of the face protecting covers is provided with a marking that indicates a cutting zone, in which the plate may be cut without damaging the vacuum insulation panel. This is usually in the form of a line of ink, but could also be an indentation, for example.

In one embodiment of the invention, at least one edge of the thermal insulating plate is formed of compressible insulating material. This allows the insulation plate to be fitted closely to adjacent insulation plates ensuring that there are gaps between the insulation plates. The compressible insulating material can be any insulating material that can be compressed by pressing the insulation plate against an adjacent insulation plate during installation. Preferably, the compressible insulation material is compressible by at least 10%, more preferably by at least 30% and even more preferably by at least 50%. Preferably, the compressible insulating material is a man-made vitreous fibre element comprising man-made vitreous fibres and binder and having a density of less than 70 kg/m³, preferably less than 50 kg/m³, more preferably less than 40 kg/m³. The compressible insulating material preferably extends from the side edge by a distance of from 20 to 150mm, preferably from 30 to 100mm, more preferably from 30 to 50mm. The compressible thermal insulating material can be attached directly to the vacuum insulation panel, or it can be attached to a side protecting cover, e.g. by gluing. In a particularly preferred embodiment, the thermal insulation plate is square or rectangular and exactly two adjacent edges of the thermal insulation plate are formed of a compressible insulating material. This allows a degree of tolerance in both dimensions in sizing and positioning the thermal insulation plate on the surface being insulated so as to ensure that there are no gaps between adjacent thermal insulation panels. By not providing compressible thermal insulating material on two of the edges, a greater proportion of the surface being insulated can be covered by the vacuum insulation panels. In this embodiment, it is preferred that exactly two adjacent edges of the thermal insulation plate, opposite to those edges formed of a compressible insulating material, are formed of a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometres. These edges are generally formed by the further protecting covers which extend from the side edges of the vacuum insulation panel to the edges of the thermal insulation plate. Forming two adjacent edges of the thermal insulation plate from compressible insulating material and the other two adjacent edges of the thermal insulation plate from the polymeric foam composite material allows the plate to be cut to size in both dimensions, by cutting the edges formed of the polymeric foam composite material, and then for minor errors in the cutting process to be tolerated when the thermal insulation plates are positioned on the surface being insulated, because the compressible thermal insulating material avoids the presence of any gaps between the plates. To achieve this, the plates are positioned on the surface such that edges formed of the polymeric foam composite material abut edges of adjacent plates formed of compressible thermal insulating material.

A further aspect of the invention relates to a thermally insulated structure comprising a surface and a plurality of adjacent thermal insulation plates as described above. Generally, the thermal insulation plates are positioned on the surface so as to abut each other. The structure can be a building wall or a wall in a boat, for example. The thermal insulation plates can be fixed to the surface by fixing means such as an adhesive and/or by mechanical fastening means, such as dowels. In one embodiment, the structure further comprises joint cover plates that overlie at least two adjacent thermal insulation plates. This is particularly useful where the edges of the thermal insulation plates are not formed from compressible insulating material, so the presence of small gaps between the thermal insulation plates is more likely. The joint cover plates cover the points at which the thermal insulation plates abut each other to ensure that coverage of the surface is substantially complete.

Preferably, the joint cover plates are formed from the polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometers. Alternatively, the joint cover plates can take the same form as the thermal insulation plates described above, comprising: a vacuum insulation panel having a first major face, a second major face and side edges joining the first and second major faces; and protecting covers, each formed from the polymeric foam composite material, wherein the protecting covers are affixed to the vacuum insulation panel so as to cover substantially the entire first major face and substantially the entire second major face of the vacuum insulation panel.

A further aspect of the invention relates to a method for constructing a thermally insulated structure as described above. The method comprises positioning and fastening the thermal insulation plates on the surface. In a preferred embodiment, the thermal insulation plates are according to the preferred embodiment in which a further protecting cover is affixed to the vacuum insulation panel so as to cover at least one side edge of the vacuum insulation panel substantially completely, and wherein the further protecting cover is formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometres. In this embodiment, the method comprises a first step of adjusting the size of at least one insulation plate, by cutting off at least a portion of at least one protecting cover that covers a side edge of the vacuum insulating panel.

The method preferably further comprises a step of positioning and fastening joint cover insulation plates as described above such that the joint cover insulation plates overlie at least two adjacent thermal insulation plates.

Polymeric Foam Composite Material

As the material of the protecting covers, the invention makes use of the polymeric foam composite material described in our earlier application filed on 18 August 201 1 and having the application number EP 1 1 177971 .6 and in our international application PCT/EP2012/066196 filed on 20 August 2012. The disclosure of those applications is incorporated herein by reference. The polymeric foam composite material used in the present invention can be produced from a foamable composition comprising a foam pre-cursor and man- made vitreous fibres, wherein at least 50% by weight of the man-made vitreous fibres have a length of less than 100 micrometres. The weight percentage of fibres in the polymeric foam composite material or in the foamable composition above or below a given fibre length is measured with a sieving method. A representative sample of the man-made vitreous fibres is placed on a wire mesh screen of a suitable mesh size (the mesh size being the length and width of a square mesh) in a vibrating apparatus. The mesh size can be tested with a scanning electron microscope according to DIN ISO3310. The upper end of the apparatus is sealed with a lid and vibration is carried out until essentially no further fibres fall through the mesh (approximately 30 mins). If the percentage of fibres above and below a number of different lengths needs to be established, it is possible to place several screens with incrementally increasing mesh sizes on top of one another. The fibres remaining on each screen are then weighed.

According to the invention, the man-made vitreous fibres present in the polymeric foam composite must have at least 50% by weight of the fibres with a length less than 100 micrometres as measured by the method above.

By reducing the length of man-made vitreous fibres that are present in the foamable composition and in the polymeric foam composite, a larger quantity of fibres can be included in the foamable composition before an unacceptably high viscosity is reached. As a result, the compressive strength, fire resistance, and in particular the compression modulus of elasticity of the resulting foam can be improved. Previously, it had been thought that ground fibres having such a low length would simply act as a filler, increasing the density of the foam. However, by using mineral fibres with such a high proportion of short fibres, far higher levels of fibres can be incorporated into the foam precursor and the resulting foam. The result of this is that significant increases in the compressive strength and, in particular, the compression modulus of elasticity of the foam can be achieved.

Preferably, the length distribution of the man-made vitreous fibres present in the polymeric foam composite or foamable composition is such that at least 50% by weight of the man-made vitreous fibres have a length of less than 75 micrometres, more preferably less than 65 micrometres.

Preferably, at least 60% by weight of the man-made vitreous fibres present in the polymeric foam composite or foamable composition have a length less than 100 micrometres, more preferably less than 75 micrometres and most preferably less than 65 micrometres.

Generally, the presence of longer man-made vitreous fibres in the polymeric foam composite or foamable composition is found to be a disadvantage in terms of the viscosity of the foamable composition and the ease of mixing. Therefore, it is preferred that at least 80%, or even 85 or 90% of the man-made vitreous fibres present in the polymeric foam composite or foamable composition have a length less than 125 micrometres. Similarly, it is preferred that at least 95%, more preferably at least 97% or 99% by weight of the man-made vitreous fibres present in the polymeric foam composite or foamable composition have a length less than 250 micrometres.

The greatest compressive strength can be achieved when at least 90% by weight of the fibres have a length less than 100 micrometers and at least 75% of the fibres by weight have a length less than 65 micrometers.

Man-made vitreous fibres having the length distribution discussed above have been found generally to sit within the walls of the cells of the foam composite, without penetrating the cells to a significant extent. Therefore, it is believed that a greater percentage by weight of the fibres in the composite contribute to increasing the strength of the composite rather than merely increasing its density.

It is also preferred that at least some of the fibres present in the foam composite material, for example at least 0.5% or at least 1 % by weight, have a length less than 10 micrometers. These very short fibres are thought to be able to act as nucleating agents in the foam formation process. The action of very short fibres as nucleating agents can favour the production of a foam with numerous small cells rather than fewer large cells. The fibres present in the polymeric foam composite or in the foamable composition can be any type of man-made vitreous fibres, but are preferably stone fibres. In general, stone fibres have a content by weight of oxides as follows:

Si0₂ 25 to 50%, preferably 38 to 48%

Al₂0₃ 12 to 30%, preferably 15 to 28%

Ti02 up to 2%

Fe₂0₃ 2 to 12%

CaO 5 to 30%, preferably 5 to 18%

MgO up to 15% preferably 1 to 8% Na₂0 up to 15%

K₂0 up to 15%

P₂0₅ up to 3%

MnO up to 3%

B₂0₃ up to 3%.

These values are all quoted as oxides, with iron expressed as Fe₂0₃, as is conventional. An advantage of using fibres of this composition in the polymeric foam composite material, especially in the context of polyurethane foams, is that the significant level of iron and alumina in the fibres can act as a catalyst in formation of the foam. This effect is particularly relevant when at least some of the iron in the fibres is present as ferric iron, as is usual and/or when the level of AI2O3 is particularly high such as 15 to 28% or 18 to 23%.

An alternative stone wool composition useful in the invention, has oxide contents by weight in the following ranges:

Si0₂ 37 to 42%

Al₂0₃ 18 to 23%

CaO + MgO 34 to 39%

Fe₂0₃ up to 1 %

Na₂0 + K₂0 up to 3% Again, the high level of alumina in fibres of this composition can act as a catalyst in the formation of a polyurethane foam. Whilst stone fibres are preferred, the use of glass fibres, slag fibres and ceramic fibres is also possible.

The man-made vitreous fibres present in the polymeric foam composite and foamable composition are discontinuous fibres. The term "discontinuous man- made vitreous fibres" is well understood by those skilled in the art. Discontinuous man-made vitreous fibres are, for example, those produced by internal or external centrifugation, for example with a cascade spinner or a spinning cup. Traditionally, fibres produced by these methods have been used for insulation, whilst continuous glass fibres have been used for reinforcement in composites. Continuous fibres (e.g. continuous E glass fibres) are known to be stronger than discontinuous fibres produced by cascade spinning or with a spinning cup (see "Impact of Drawing Stress on the Tensile Strength of Oxide Glass Fibres", J. Am. Ceram. Soc, 93 [10] 3236-3243 (2010)). Nevertheless, it has been found that foam composites comprising short, discontinuous fibres have a compressive strength that is at least comparable with foam composites comprising continuous glass fibres of a similar length. This unexpected level of strength is combined with good fire resistance, a high level of thermal insulation and cost efficient production.

In order to achieve the required length distribution of the fibres, it will usually be necessary for the fibres to be processed further after production with a cascade spinner or a spinning cup. The further processing will usually involve grinding or milling of the fibres for a sufficient time for the required length distribution to be achieved.

Usually, the fibres present in the polymeric foam composite and foamable composition have an average diameter of from 2 to 7 micrometres. Preferably, the fibres have an average diameter of from 2 to 6 micrometres, more preferably the fibres have an average diameter of from 3 to 6 micrometres. Thin fibres as preferred in the invention are believed to provide a higher level of thermal insulation to the composite than thicker fibres, but without a significant reduction in strength as compared with thicker fibres as might be expected. The average fibre diameter is determined for a representative sample by measuring the diameter of at least 200 individual fibres by means of the intercept method and scanning electron microscope or optical microscope (1000x magnification).

The foamable composition that can be used to produce the polymeric foam composite comprises a foam precursor and man-made vitreous fibres. The foam precursor is a material that either polymerises (often with another material) to form a polymeric foam or is a polymer that can be expanded with a blowing agent to form a polymeric foam. The composition can be any composition capable of producing a foam on addition of a further component or upon a further processing step being carried out.

Preferred foamable compositions are those capable of producing polyurethane foams. Polyurethane foams are produced by the reaction of the polyol with an isocyanate in the presence of a blowing agent. Therefore, in one embodiment, the foamable composition comprises, in addition to the man-made vitreous fibres, a polyol as the foam precursor. In another embodiment, the foamable composition comprises, in addition to the man-made vitreous fibres, an isocyanate as the foam precursor. In another embodiment, the composition comprises a mixture of an isocyanate and a polyol as the foam precursor.

If the foam precursor is a polyol, then foaming can be induced by adding a further component comprising an isocyanate. If the foam precursor is an isocyanate, foam formation can be induced by the addition of a further component comprising a polyol.

Suitable polyols for use either as the foam precursor or to be added as a further component to the foamable composition to induce foam formation are commercially available polyol mixtures from, for example, Bayer Material Science, BASF or DOW Chemicals. Commercially available polyol compositions are often supplied as a pre-mixed component that comprises polyol and any or all of catalyst(s), flame retardant(s), surfactants and water, the latter which can act as a chemical blowing agent in the foam formation process. Generally it comprises all of these. Such a pre-formed blend of polyol with additives is commonly known as a pre-polyol.

The isocyanate for use either as the foam precursor or to be added as a further component to the foamable composition to induce foam formation is selected on the basis of the density and strength required in the foam composite as well as on the basis of toxicity. It can, for example, be selected from methylene polymethylene polyphenol isocyanates (PMDI), methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), PMDI or MDI being preferred. One particularly suitable example is diphenylmethane-4,4'-diisocyanate. Other suitable isocyanates are commercially available from, for example, Bayer Material Science, BASF or DOW Chemicals.

In order to form a foam composite, a blowing agent is required. The blowing agent can be a chemical blowing agent or a physical blowing agent. In some embodiments, the foamable composition comprises a blowing agent. Alternatively, the blowing agent can be added to the foamable composition together with a further component that induces foam formation. In the context of polyurethane foam composites, in a preferred embodiment, the blowing agent is water. Water acts as a chemical blowing agent, reacting with the isocyanate to form CO₂, which acts as the blowing gas.

When the foam-precursor is a polyol, in one embodiment, the foamable composition comprises water as a blowing agent. The water is usually present in such a foamable composition in an amount from 0.3 to 2 % by weight of the foamable composition.

As an alternative, or in addition, a physical blowing agent, such as liquid CO₂ or liquid nitrogen could be included in the foamable composition or added to the foamable composition as part of the further component that induces foam formation.

The foamable composition, in an alternative embodiment, is suitable for forming a phenolic foam. Phenolic foams are formed by a reaction between a phenol and an aldehyde in the presence of an acid or a base. A surfactant and a blowing agent are generally also present to form the foam. Therefore, the foamable composition could comprise, in addition to the man-made vitreous fibres, a phenol and an aldehyde (the foam precursor), a blowing agent and a surfactant. Alternatively, the foamable composition could comprise as the foam precursor, a phenol but no aldehyde, or an aldehyde but no phenol.

Whilst foamable compositions suitable for forming polyurethane or phenolic foams are preferred, it is also possible to use foamable compositions suitable for forming polyisocyanurate, expanded polystyrene and extruded polystyrene foams.

In an alternative embodiment, the polyurethane foam composite is especially a polyisocyanurate foam composite, where the blowing agent is preferably pentane. Pentane has the advantage over other blowing agents that it is more environmentally friendly and cost effective than for instance HFC blowing agents. Pentane can be c-pentane, i-pentane, or n-pentane or a mixture of two or more of these. The choice between c-pentane, i-pentane and n-pentane is dependent on the production method. They are quite different in boiling point, initial thermal conductivity, aged thermal conductivity and price. The preferred pentane in this invention is n-pentane based on the price and aged thermal conductivity.

The foamable composition that can be used to make the foam composite used in the invention can contain additives in addition to the foam precursor and the man-made vitreous fibres. When it is desired to include additives in the foam composite, as an alternative to including the additives in the foamable composition comprising man-made vitreous fibres, the additive can be included with a further component that is added to the foamable composition to induce foam formation.

As an additive, it is possible for the composition or the foam composite to comprise a fire retardant such as expandable powdered graphite, aluminium trihydrate or magnesium hydroxide. The amount of fire retardant in the composition is preferably from 3 to 20% by weight, more preferably from 5 to 15% by weight and most preferably from 8 to 12 % by weight. The total quantity of fire retardant present in the polymeric foam composite material is preferably from 1 to 10%, more preferably from 2 to 8% and most preferably from 3 to 7 % by weight. Alternatively, or in addition, the foamable composition or foam composite can comprise a flame retardant such as nitrogen- or phosphorus-containing polymers. The fibres used in the polymeric foam composite can be treated with binder, which, as a result, can be included in the composition and the resulting foam composite as an additive if it is chemically compatible with the composition. The fibres used usually contain less than 10% binder based on the weight of the fibres and binder. The binder is usually present in the foamable composition at a level less than 5% based on the total weight of the foamable composition. The foam composite usually contains less than 5% binder, more usually less than 2.5% binder. In a preferred embodiment, the man-made vitreous fibres used are not treated with binder. In some circumstances, it is advantageous, before mixing the man-made vitreous fibres into the foamable composition, to treat the fibres with a surfactant, usually a cationic surfactant. The surfactant could, alternatively, be added to the composition as a separate component. The presence of a surfactant, in particular a cationic surfactant, in the composition and as a result in the polymeric foam composite material has been found to provide easier mixing and, therefore, a more homogeneous distribution of fibres within the foamable composition and the resulting foam.

One advantage of the described polymeric foam composite is that it is possible to incorporate larger percentages of fibres into the foamable composition, and therefore into the resulting foam, than would be the case with longer fibres. This allows higher levels of fire resistance and compressive strength to be achieved. Preferably, the composition comprises at least 15% by weight, more preferably at least 20% by weight, most preferably at least 35% by weight of man-made vitreous fibres. The polymeric foam composite material itself preferably comprises at least 10% by weight, more preferably at least 15% by weight, most preferably at least 20% by weight of man-made vitreous fibres. Usually the foamable composition comprises less than 85% by weight, preferably less than 80%, more preferably less than 75% by weight man-made vitreous fibres. The resulting foam composite usually contains less than 80% by weight, preferably less than 60%, more preferably less than 55% by weight man- made vitreous fibres.

The polymeric foam composite used in the invention comprises a polymeric foam and man-made vitreous fibres. The foam composite can be formed from the foamable composition as described above. It is preferred that the polymeric foam is a polyurethane foam or a phenolic foam. Polyurethane foams are most preferred due to their low curing time.

The first step in the production of the polymeric foam composite material is to form the foamable composition comprising the foam precursor and the mineral fibres. The fibres can be mixed into the foam precursor by a mechanical mixing method such as use of a rotary mixer or simply by stirring. Additives as discussed above can be added to the foamable composition.

Once the fibres and foam precursor have been mixed, the formation of a foam can then be induced. The manner in which the foam is formed depends on the type of foam to be formed and is known to the person skilled in the art for each type of polymeric foam. In this respect, reference is made to "Handbook of Polymeric Foams and Foam Technology" by Klempner et al. For example, in the case of a polyurethane foam, the man-made vitreous fibres can be mixed with a polyol as the foam precursor. The foamable composition usually also comprises water as a chemical blowing agent. Then foaming can be induced by the addition of an isocyanate. In the case where a further component is added to the foamable composition to induce foaming, this can be carried out in a high pressure mixing head as commercially available. In one embodiment, foam formation is induced by the addition of a further component and the further component comprises further man-made vitreous fibres, wherein at least 50% by weight of the further man-made vitreous fibres have a length of less than 100 micrometres. Including man-made vitreous fibres in both the foamable composition and the further component can increase the overall quantity of fibres in the foam composite, by circumventing the practical limitation on the quantity of fibres that can be included in the foamable composition itself. For example in the context of polyurethane foam composites a foamable composition could comprise a polyol, man-made vitreous fibres and water. Then foaming could be induced by the addition, as the further component, of a mixture of isocyanate and further man-made vitreous fibres, wherein at least 50% of the man-made vitreous fibres have a length of less than 100 micrometers.

In essentially the same process, the mixture of isocyanate and man-made vitreous fibres could constitute the foamable composition, and the mixture of polyol, water and man-made vitreous fibres could constitute the further component.

The quantity of man-made vitreous fibres in the further component is preferably at least 10 % by weight, based on the weight of the further component. More preferably the quantity is at least 20% or at least 30% based on the weight of the further component. Usually, the further component comprises less than 80% by weight, preferably less than 60%, more preferably less than 55% by weight man- made vitreous fibres.

The polymeric foam composite is the material that provides compressive strength and resistance to compression to the thermal insulating element. Therefore, preferably the polymeric foam composite has a compressive strength of at least 1500 kPa and a compression modulus of elasticity of at least 60,000 kPa as measured according to European Standard EN 826:1996. The following are examples of the polymeric foam composite materials as used in the invention as compared with other polymeric foam composite materials.

Example 1 (comparative)

100.0 g of a commercially available composition of diphenylmethane-4,4'- diisocyanate and isomers and homologues of higher functionality, and 100.0 g of a commercially available polyol formulation were mixed by propellers for 20 seconds at 3000 rpm. The material was then placed in a mold to foam, which took about 3 min. The following day, the sample was weighed to determine its density and the compression strength and compression modulus of elasticity were measured according to European Standard EN 826:1996.

Compressive strength: 1 100 kPa

Compression modulus of elasticity: 32000 kPa

Example 2

100.0 g of the same commercially available polyol formulation as used in Example 1 was mixed with 200.0 g ground stone wool fibres, over 50% of which have a length less than 64 micrometers, for 10 seconds. Then 100.0 g of the commercially available composition of diphenylmethane-4,4'-diisocyanate was added and the mixture was mixed by propellers for 20 seconds at 3000 rpm. The material was then placed in a mold to foam, which took about 3 min. The following day, the sample was weighed to determine its density and the compression strength and compression modulus of elasticity were measured according to European Standard EN 826:1996.

Compressive strength: 1750 kPa

Compression modulus of elasticity: 95000 kPa

Example 3 (comparative) 100.0 g of the same commercially available polyol formulation as used in Examples 1 and 2 was mixed for 10 seconds with 50.0 g stone fibres having a different chemical composition from those used in Example 2 and having an average length of 300 micrometers. 100.0 g of the commercially available composition of diphenylmethane-4,4'-diisocyanate was added. The mixture was then mixed by propellers for 20 seconds at 3000 rpm. The material was placed in a mold to foam, which takes about 3 min. The following day, the sample was weighed to determine its density and the compression strength and compression modulus of elasticity were measured according to European Standard EN 826:1996.

Compressive strength: 934 kPa

Compression modulus of elasticity: 45000 kPa Example 4

Example 3 was repeated, but the fibres were ground such that greater than 50% of the fibres had a length less than 64 micrometers. Following this grinding it became possible to mix 200g of the fibres with the polyol mixture.

Compressive strength: 1785 kPa

Compression modulus of elasticity: 1 15000 kPa.

Example 5

Small flame tests were carried out according to ISO/DIS 1 1925-2 to establish the fire resistance of polymeric foam composites as used in the invention compared with the fire resistance of composites comprising quartz sand rather than fibres according to the invention. The foam used was polyurethane foam. The fibres used had a composition within the following ranges.

Si0₂ 38 to 48wt%

Al₂0₃ 17 to 23wt%

Ti02 up to 2wt% Fe₂0₃ 2 to 12wt%

CaO 5 to 18wt%

Mg0 4 to 10wt%

Na₂0 up to 15wt%

K₂0 up to 15wt%

P₂0₅ up to 3wt%

MnO up to 3wt%

B₂0₃ up to 3wt% The quartz sand used had a particle size up to 2mm. In each composite tested, expanding graphite was included as a fire retardant. The test involved measuring the height of a flame from each composite under controlled conditions. The results were as follows:

Brief Description of the Drawings Figure 1 is a side on view of a thermal insulating panel according to the invention.

Figure 2 is a cross-section view of a preferred embodiment of the thermal insulating panel according to the invention having a further protecting cover is affixed to the vacuum insulation panel so as to cover at least one side edge of the vacuum insulation panel substantially completely. Figure 3 shows a preferred embodiment of the thermal insulating panel according to the invention having a further protecting cover is affixed to the vacuum insulation panel so as to cover at least one side edge of the vacuum insulation panel substantially completely.

Figure 4 shows a preferred embodiment of the thermal insulating panel according to the invention wherein at least one edge of the thermal insulating plate is formed of compressible insulating material.

Figure 5 shows an insulated structure according to the invention.

Figure 6 is a cross section view of an insulated structure according to the invention.

Figure 7 is an environmental scanning electron microscope image of a polyurethane foam composite material as used according to the invention.

Detailed Description of the Drawings

Figure 1 shows a thermal insulating plate 1 comprising a vacuum insulation panel 2 and protecting covers 5. The vacuum insulation panel 2 has a first major face 3 and a second major face 4 and side edges 6 joining the first and second major faces 3 and 4. The protecting covers 5 are each formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometers. Figure 2 shows an embodiment of the invention in which further protecting covers 7 are affixed to the vacuum insulation panel 2 so as to cover at least one side edge 6 of the vacuum insulation panel 2 substantially completely. The further protecting covers 7 are each formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometers. The further protecting covers 7 are shown as separate pieces of foam composite material, but can also be formed as a single piece of polymeric foam composite material together with the protecting covers 5 that cover the first and second major faces 3, 4 of the vacuum insulation panel 2.

Figure 3 shows a section view of an embodiment of the invention in which further protecting covers 7 are affixed to the vacuum insulation panel 2 so as to cover the side edges 6 of the vacuum insulation panel 2 substantially completely. Here, the protecting covers 5 and the further protecting covers 7 are formed as a single piece of the polymeric foam composite material. The vacuum insulation panel 2 could also be covered by a further protecting cover at its near side edge and thus be completely encased within polymeric foam composite material. Markings 8 show the extent of the vacuum insulation panel 2 within the thermal insulation plate 1 and thus the area in which the plate 1 can be cut.

Figure 4 shows a preferred embodiment of the thermal insulation plate of the invention. The vacuum insulation panel (not shown) is covered by protecting covers 5 on its two major faces and by further protecting covers 7 formed from polymeric foam composite material on two adjacent side edges. Two adjacent edges 10 of the thermal insulation plate 1 are formed from the polymeric foam composite material. The other two side edges 1 1 of the thermal insulation plate are formed from compressible thermal insulating material 9. Markings 8 show the region in which the thermal insulation plate 1 can be cut to size.

Figure 5 shows a plurality of thermal insulation plates 1 as shown in Figure 4 in place on an insulated structure 13. The structure 13 has a surface 12 on which the thermal insulation plates 1 are fixed. The four thermal insulation plates 1 shown abut each other and are positioned such that the edges 1 1 formed from compressible thermal insulation material 9 abut the edges 10 of the adjacent panels formed from the polymeric foam composite material. Therefore, there is compressible thermal insulating material 9 present at every joint. Figure 6 shows an embodiment of the insulated structure of the invention. The structure 13 has a surface 12 that is covered with thermal insulation plates 1 . The internal structure of the thermal insulation plates 1 is not shown. The joints between the thermal insulation plates 1 are covered by joint covering plates 14, which are adhered to the thermal insulation plates 1 . Preferably, as is shown, the joint insulation plates 14 sit within indents 15 at the edges of the thermal insulation plates 1 .

Figure 7 is an environmental scanning electron microscope image of a polyurethane foam composite material as used according to the invention, in which the fibres have a length distribution such that 95% by weight of the fibres have a length below 100 micrometers and 75% by weight of the fibres have a length below 63 micrometers. The composite contains 45% fibres by weight of the composite. The instrument used was ESEM, XL 30 TMP (W), FEI/Philips incl. X-ray microanalysis system EDAX. The sample was analysed in low vacuum and mixed mode (BSE/SE).

The image shows the cellular structure of the foam and demonstrates that the man-made vitreous fibres generally sit in the walls of the cells of the foam without penetrating into the cells themselves to a significant extent.

Claims

1 . A thermal insulation plate comprising:

2. A thermal insulation plate according to claim 1 , wherein a further protecting cover is affixed to the vacuum insulation panel so as to cover at least one side edge of the vacuum insulation panel substantially completely, and wherein the further protecting cover is formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometres.

3. A thermal insulation plate according to claim 2, wherein protecting covers are affixed to the vacuum insulation panel so as to cover every side edge of the vacuum insulation panel substantially completely, wherein each protecting cover is formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometres.

4. A thermal insulation plate according to any preceding claim, wherein at least one edge of the thermal insulating plate is formed of compressible insulating material.

5. A thermal insulation plate according to any preceding claim, wherein the thermal insulation plate is square or rectangular and exactly two adjacent edges of the thermal insulation plate are formed of a compressible insulating material.

6. A thermal insulation plate according to claim 5, wherein exactly two adjacent edges of the thermal insulation plate, opposite to those edges formed of a compressible insulating material, are formed of a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometres.

7. A thermal insulation plate according to any preceding claim, wherein at least 60% by weight of the man-made vitreous fibres present in the polymeric foam composite material have a length less than 65 micrometers.

8. A thermal insulation plate according to any preceding claim, wherein at least 80% by weight of the man-made vitreous fibres present in the polymeric foam composite material have a length less than 125 micrometers.

9. A thermal insulation plate according to any preceding claim, wherein at least 95% by weight of the man-made vitreous fibres present in the polymeric foam composite material have a length less than 250 micrometers.

10. A thermal insulation plate according to any preceding claim, wherein the man-made vitreous fibres present in the foam composite material have an average diameter of from 2 to 6, preferably from 3 to 6 micrometers.

1 1 . A thermal insulation plate according to any preceding claim, wherein the man-made vitreous fibres present in the polymeric foam composite material have a content of oxides as follows:

Si0₂ 25 to 50wt%, preferably 38 to 48wt%

Al₂0₃ 12 to 30wt%, preferably 15 to 28wt%, more preferably 17 to 23wt%

Ti0₂ up to 2wt%

Fe₂0₃ 2 to 12wt%

CaO 5 to 30wt%, preferably 5 to 18wt%

MgO up to 15wt%, preferably 4 to 10wt%

Na₂0 up to 15wt%

K₂0 up to 15wt%

P₂0₅ up to 3wt%

MnO up to 3wt%

B₂0₃ 0 to 3wt%.

12. A thermal insulation plate according to any preceding claim, wherein the polymeric foam is a polyurethane foam.

13. A thermal insulation plate according to any preceding claim, wherein the polymeric foam composite material comprises at least 10% by weight, preferably at least 15% by weight, more preferably at least 20% by weight of man-made vitreous fibres.

14. A thermal insulation plate according to any preceding claim, wherein the polymeric foam composite material comprises less than 80% by weight, preferably less than 60%, more preferably less than 55% by weight of man- made vitreous fibres.

15. A thermally insulated structure comprising a surface and a plurality of adjacent thermal insulation plates according to any of claims 1 to 14 disposed on the surface, wherein the thermal insulation plates preferably abut each other.

16. A structure according to claim 15, further comprising joint cover plates that overlie at least two adjacent thermal insulation plates.

17. A structure according to claim 16, wherein the joint cover plates are formed from a polymeric foam composite material comprising a polymeric foam and man-made vitreous fibres produced with a cascade spinner or a spinning cup, wherein at least 50% by weight of the man-made vitreous fibres present in the foam composite material have a length of less than 100 micrometers.

18. A method for constructing a thermally insulated structure comprising a surface and a plurality of adjacent thermal insulation plates according to any of claims 1 to 14, wherein the method comprises positioning and fastening the thermal insulation plates on the surface.

19. A method according to claim 18, wherein the thermal insulation plates are as defined in claim 2 and the method comprises a first step of adjusting the size of at least one insulation plate, by cutting off at least a portion of at least one protecting cover that covers a side edge of the vacuum insulating panel.

20. A method according to claim 18 or claim 19, further comprising positioning and fastening joint cover insulation plates such that the joint cover insulation plates overlie at least two adjacent thermal insulation plates.