GB2494544A

GB2494544A - Laminated non-woven fabric comprising meltblown and spunbond layers, used as roofing underlay

Info

Publication number: GB2494544A
Application number: GB201216266A
Authority: GB
Inventors: David John Avril; George Murray Baxter
Original assignee: Don and Low Ltd
Current assignee: Don and Low Ltd
Priority date: 2012-09-12
Filing date: 2012-09-12
Publication date: 2013-03-13
Anticipated expiration: 2032-09-12
Also published as: GB201216266D0; GB2494544B

Abstract

The laminate comprises a melt-blown layer 22 and at least one spun-bond layer 24, 26, preferably as an SMS laminate. The melt blown layer 22 has a basis weight ² 35 (25-34) g/m2 and comprises fibres having a diameter ² 2.5 (2.2-2.4) Âµm. Preferably the laminate has a hydrostatic head > 100 cm and air permeability > 20 l/m2/s. Preferably, the melt blown and spun bond layers comprise polyolefin, especially polypropylene fibres. The preferred spun bond layers 24, 26 have basis weight = 15-150 g/m2. The preferred laminate, containing fluorocarbon hydrophobic melt additive, UV absorber, flame retardant, pigment or plasticiser, is point bonded with heated calender rollers. The laminate is used with an unsupported or fully supported roof.Â Â

Description

IMPROVED FABRIC

FIELD OF INVENTION

The invention relates to a laminated fabric and a method of producing same.

The laminated fabric is suitable for a variety of applications. For example, laminated fabrics of the present invention may be comprised in building materials, such as roofing underlay. The invention relates to lighter-weight air and water permeable laminated fabrics.

BACKGROUND TO INVENTION

Vapour permeable fabrics known in the art as possessing good barrier properties to water droplets and/or solid particles generally comprise co-extruded or monolayer films comprising a plurality of micropores or monolithic films. Such vapour permeable films may be used as roofing underlays due to their ability to assist in evacuating unwanted moisture vapour from roof spaces. Generally these vapour permeable films that provide a barrier to the passage of water droplets are air barrier materials known as vapour permeable/air barrier roofing underlays.

However, in the UK, it is increasingly acknowledged that roofing underlays that are both vapour permeable and air permeable are very effective at evacuating large amounts of moisture vapour from the roof space beneath the underlay. Air permeable and vapour permeable underlays are breathable' in the true sense of the word and are acknowledged to form an effective alternative to traditional mechanical vents in cold' unoccupied roof spaces.

That is to say that the underlay is sufficiently breathable such that any moisture entering the roofspace from the occupied living area underneath will be evacuated from the roofspace into the atmosphere through the underlay itself.

There are two typical types of roof construction: warm' roots -where the insulation is at rafter level with the roofspace itselt being occupied, and cold' roof spaces -where the insulation is laid on the floor of the roofspace and it is unoccupied.

Traditionally, unwanted moisture is evacuated from cold' roof spaces via the introduction of mechanical vents, typically at the eaves and the ridge. These mechanical vents allow atmospheric moisture to enter and leave the roofspace, which effectively transports unwanted moisture to the outside atmosphere. The use of mechanical vents at the eaves and/or ridge of a cold' unoccupied root space can increase the heat losses from a property by various mechanisms including (i) increasing the temperature gradient between the occupied and unoccupied spaces, and (ii) air entering the roof space via mechanical vents at the eaves can pass through the glass wool insulation laid on the tloor of the roofspace, thus reducing the etficiency of the insulation.

The use ot an air and vapour permeable rooting underlay as an alternative to mechanical ventilation may reduce heat losses and improve the thermal efficiency ot a property, whilst at the same time reducing the risk ot condensation. The superior performance of air permeable fabrics when compared to air barrier materials to reduce condensation in energy etficient cold' (unoccupied) unventilated roofspaces has been acknowledged by the National House Building Council (NHBC) in the UK. This national body now insist that, for any new build domestic property that incorporates a non-ventilated cold' roof space, i.e. where traditional mechanical vents are eliminated from the root construction, only roofing underlays that are both air and vapour permeable are used.

Typical air and vapour permeable underlay fabrics include nonwoven laminated materials comprising a meltblown layer, such as those described in ER 0742305 Al (Don & Low Limited).

Whilst it is desirable that roofing underlays are air permeable to assist in moisture evacuation, at the same time, roofing underlays should also possess sufficient levels of water hold-out to be fit for purpose. For instance, roofing underlays are preferably resistant to wind-driven rain and sitting water.

Conventionally those skilled in the art believed that the water hold-out performance of a non-woven laminated fabric is dictated by the weight of the meltblown layer. Use of a heavier meltblown material can impart improved levels of water hold-out to the fabric but at the cost of air permeability, as the heavier meltblown layer offers greater resistance to air flow through the fabric. Heavier meltblown materials also may lead to heavier composite fabrics which are less easy to handle when in use on a building site. The use of heavier meltblown materials to obtain higher levels of water hold-out may also significantly add to the cost of the final product, as the meltblown layer is typically the most expensive component of such laminated fabrics.

It is an object of at least one embodiment of at least one aspect of the present invention to obviate or at least mitigate one or more problems or disadvantages in the

prior art.

SUMMARY OF INVENTION

According to a first aspect of the present invention there is provided a laminated fabric, such as a roofing underlay, comprising: a first layer of meltblown material laminated to a second layer of spunbond material; wherein the meltblown material has a basis weight less than approximately 35 g/m2; and wherein the meltbiown material is formed of fibres having a fibre diameter less than approximately 2.5 pm.

Preferably the laminated fabric may comprise an air permeable laminate.

Preferably the laminated fabric may comprise a vapour permeable laminate, in particular a water vapour permeable laminate.

In use, laminated fabrics according to embodiments of the present invention may be used as building materials, for example, as roofing underlays, e.g. beneficially in unsupported and/or alternatively in fully supported (sarked) roofs. For instance, as roofing underlays in cold' pitched roof spaces. By a cold roofspace, it is meant where roofing insulation is laid on the floor of the roofspace and the roofspace is unoccupied.

In embodiments of the invention, a laminated fabric comprising a lighter weight meltblown layer formed of finer fibres may surprisingly provide increased levels of water hold-out and comparable levels of air permeability when compared to a laminated fabric comprising a heavier weight meltblown layer.

In certain embodiments of the present invention, the laminated fabric may comprise a third layer of spunbond material. The third layer of material may be laminated to one side of the first layer and the second layer may be laminated to a second side of the first layer. In certain embodiments, the first layer of meltblown material may be sandwiched between the second and third layers of spun-bond material. In these and other embodiments, the second and/or third layers of spunbond material comprise outer layers of the laminated fabric and may provide support to the meitblown layer. The second and/or third layers of spunbond material may act as an abrasion resistant, durable and/or protective cover for the meltblown material. In these and other embodiments, where the meltblown sheet is processed to form the intermediate layer of a three-layer structure, the two outer layers being spun-bonded layers, the structure may conveniently be referred to an SMS (spunbonded/meltblown/spunbonded) structure.

Laminated fabrics of the invention may show improved levels of water hold-out.

In use as a roofing underlay, improved levels of water hold-out may enable laminated fabrics of the invention to provide protection against wind-driven rain and sitting water.

Levels of water hold-out may be quantified by hydrostatic head measurements. The laminated fabric may have a hydrostatic head greater than 100cm, greater than 110cm, greater than 115cm or greater than 120cm. The laminated fabric may have a hydrostatic head between 100cm and 150cm, between 110cm and 140cm, or between 115cm and 130cm. The laminated fabric may have a hydrostatic head of approximately 120cm.

In embodiments of the invention, laminated fabrics comprising a meltblown layer which is up to 20% lighter may show maintained or improved levels of water hold-out when compared to other laminated fabrics comprising heavier meltblown layers.

The meltblown layers comprised in laminated fabrics of the invention that may be between I and 20% lighter, or between 5 and 15 % lighter than heavier meltblown layers comprised in typical laminated fabrics. In embodiments of the invention, up to about a 15% reduction in the basis weight of the meltblown layer comprised in the laminated fabric may not detrimentally impact the levels of water hold-out and air permeability of a laminated fabric.

Prior to lamination, the first layer of meltblown material may have a hydrostatic head of greater than 60cm, greater than 70cm, greater than 75cm, or greater than 80cm. Prior to lamination, the first layer of meltblown material may have a hydrostatic head between 60cm and 100cm, between 70cm and 90cm, or between 80cm and 90cm. Prior to lamination, the first layer of meltblown material may have a hydrostatic head of approximately 84cm.

The laminated fabric may be air and/or gas and/or water vapour permeable.

The laminated fabric may have an air permeability greater than 40 l/m2/s, greater than about 50 l/m2/s, or greater than about 55 l/m2/s, or greater than about 60 l/m2/s. The laminated fabric may have an air permeability between 20 lIm2Is and 100 l/m2/s, between 40 l/m2/s and 80 l/m2/s, for example between 50 I/m2/s and 70 I/m2/s. The laminated fabric may have an air permeability of approximately 60 I/m2/s.

Prior to lamination, the first layer of meitblown material may be air permeable.

Prior to lamination, the first layer of material may have an air permeability greater than about 200 l/m2/s, greater than about 225 l/m2/s, greater than about 250 l/m2/s or even greater than about 275 l/m2/s. The first layer of material may have an air permeability between about 200 l/m2/s and 300 11m2/s, or between about 250 l/m2/s and 300 11m2/s, for example between 270 l/m2/s and 290 l/m2/s. Prior to lamination, the first layer of meltblown material may have an air permeability of approximately 280 l/m2/s.

In these and other embodiments, the air permeability of the meltblown layer and/or of the laminated fabric may assist in allowing the passage of water vapour through the fabric. For example, the air permeability of the fabric may assist in evacuating moisture from a roof space, and so may reduce the risk of condensation in 1 5 roof spaces.

The first layer of meltblown material may have a basis weight between 10 g/m2 and 35 g/m2 or between 15 g/m2 and 35 g/m2, or between 20 g/m2 and 35 g/m2, or between 25 g/m2 and 34 g/m2. For example, the first layer of meltblown material may have a basis weight of approximately 30 g/m2.

The first layer of meltblown material may be formed of fibres having a fibre diameter less than approximately 2.Spm, or less than 2.4pm. The fibres in the meltblown material may have a diameter between 1pm and 2.Spm, or between 1.Spm and 2.4pm, or between 2.2 and 2.4 pm. The fibres in the meltblown material may have a fibre diameter of approximately 2.3pm.

As used herein, the fibre diameter may mean the mean or average fibre diameter of the fibres in a layer of material.

In these and other embodiments, a laminated fabric comprising a lighter weight meltblown layer formed of finer fibres, advantageously provides an increased hydrostatic head and comparable levels of air permeability when compared to a laminated fabric comprising a typical meltblown layer. Surprisingly, the use of a lighter weight meltblown does not compromise the ability of laminated fabrics of the invention to hold-out water. Without being bound by theory, the inventors hypothesise that the careful selection of fibre diameter results in a more uniform distribution of fibres throughout the meltblown layer which may give rise to the improved levels of water hold-out.

Reducing the weight of the meliblown layer may advantageously reduce the overall cost of the laminated fabric. The decrease in the overall weight of the laminated fabric may also allow easier handling of the fabric. For example, the manual handling issues associated with installing roofing underlay on a roof are reduced slightly as the laminated fabrics are lighter.

The second and/or third layer(s) of spunbond material may have a basis weight between 15 and 150 q/m2, or between 40 and 100 g/m2. The second and/or third layer(s) of spunbond material may have a basis weight of approximately 50 g/m2 or approximately 90 g/m2. The second and third layers of spunbond material may have different basis weights. For example, when used as a roofing underlay, the layer of spunbond material comprising the underside (i.e. the layer facing the roofspace) may have a lower basis weight than the opposing layer of spunbond material facing outwards.

In embodiments of the present invention, the first layer of meltblown material and the second and third layers of spunbond material may comprise polymers.

Examples of polymers from which meltblown and spunbond materials may be made include polyolefinic polymers such as polyethylene and polypropylene homopolymers and co-polymers thereof and of mixtures of homopolymers and co-polymers.

S

Preferably, the meltbiown and spunbond materials comprise polypropylene. Other polymeric materials may also be found suitable as will be apparent to the skilled reader.

Meltblown and spunbond materials may be formed of single component fibres or bicomponent fibres. Bicomponent fibres may comprise at least two different polymeric materials wherein one polymeric material may soften at a lower temperature than the other(s). Bicomponent fibres may have a core-sheath, layered or matrix-type structure. Preferably, the meltblown and spunbond materials comprise fibres formed of a single polymer component, such as hornopolymer fibres.

In embodiments, the laminated material may comprise additives. Additives may be present in the first, second and/or third layers of the laminated fabric. Additives may include hydrophobic melt additives and the like, for example an organic fluorocarbon derivative. Such additives are known in the art and may be added to polymers from which meltblown materials are made to improve their hydrophobic and/or oleophobic barrier properties. Other additives, such as UV absorbing additives may be advantageously added to the melt polymer so as to inhibit the polymer degradation due to, for example, exposure to ultraviolet light. Examples of other additives which may be comprised in the laminated material, and/or added to the meltblown material, include conventional additives such as flame retardants, pigments and plasticisers, and the like.

The fabrics of the invention may typically take the form of sheeting, strips, rolls and the like.

According to a second aspect of the present invention there is provided a method of making a laminated fabric, such as a roofing underlay, comprising: providing a first layer of meltblown material having a basis weight less than approximately 35 g/m2 and being formed of fibres having a fibre diameter less than approximately 2.5 pm; laminating the first layer of meltblown material to at least a second layer of spunbond material to provide a laminated fabric.

According to a third aspect of the present invention there is provided a method of making a laminated fabric, such as a roofing underlay, comprising: laminating a first layer of meltblown material to at least a second layer of spunbond material to provide a laminated fabric; wherein the meltblown material has a basis weight less than approximately 35 g/m2 and is formed of fibres having a fibre diameter less than approximately 2.5 pm.

The method may further comprise laminating the first layer of meltblown material to a third layer of spunbond material.

Laminating may comprise passing the first, second and/or third layers of material through calender rollers, preferably through heated calender rollers and/or under pressure. Typically temperatures for laminating a polypropylene SMS may be between 12000 and 170 °C and pressures between 30 N/mm -150 N/mm may be employed in the laminating process. SMS fabrics produced with different polymers may require different lamination process conditions dependant on polymer melt temperature Laminating meltblown sheets to such supportive, open layers, such as the second and/or third layer of spunbond material, may be effected by passing the sheet materials simultaneously through, for example, a point bonding calendering process. In this process, which is known in the art, a combination of heat and pressure is applied in an intermittent pattern known as point bonding. The area of such bond points is typically 5% to 40% of the total area of the bonded materials and may preferably be in the range 15% to 20%.

The method may comprise producing a first layer of meltblown material by reducing the throughput of a meltblown extrusion line which results in reduced fibre diameters, for example fibre diameters less than 2.5 pm. There are a variety of techniques for modifying fibre diameter as would be known to those skilled in the art.

For instance, the use of spinneret die plates with varying hole sizes and/or the use of different polymers.

The method may comprise providing a pre-compressed first layer of meltblown material. The method may comprise compressing a first layer of meltblown material, preferably prior to lamination.

Compressing a material typically involves applying pressure, sometimes with gentle heating. However, as would be understood by the person skilled in the art, pressures and/or temperatures used in compressing step are not high enough to cause softening of fibres and/or filaments in the material.

According to a fourth aspect of the present invention there is provided a roof which comprises a laminated fabric according to the first aspect of the present invention.

Advantageously, the roof may be an unsupported roof, such as an unsupported cold-pitched roof or alternatively it may be a fully supported (sarked) roof.

A fully supported or sarked roof may comprise boards or sheets placed onto rafters. In such embodiments, the laminated fabric may be placed directly on the rigid upper surface of the boards or sheets (hence the underlay is termed as being supported').

An unsupported roof may comprise a laminated fabric, in particular a roofing underlay, draped between rafters in a roof (hence the underlay is termed as being unsupported'). Battens may be placed on top of the underlay onto which the tile and slates may be secured.

According to a fifth aspect of the present invention, there is provided a building with a roof comprising a laminated fabric according to the first aspect of the present invention.

According to a sixth aspect of the present invention there is provided a use of a laminated fabric as defined in the first, second or third aspects as a building material.

In certain embodiments the laminated material may be used as a roofing underlay. For example, the laminated material may be used on an unsupported roof or a fully supported (sarked) roof.

The term "meltblown" as used herein may refer to a non-woven material formed by meltblowing. Meltblown materials typically comprise short length fibres formed when molten polymer is extruded into a high velocity gas stream. These short length fibres may typically be laid out onto a moving belt and bond to one another to form a web.

The term spunbond" as used herein may refer to a non-woven material formed by spin laying. Spunbond materials may typically comprise continuous filaments formed when molten polymer is extruded through a spinneret. These continuous filaments may typically be laid out onto a moving screen and bond to one another to form a web.

Spunbond filaments are typically 15 -25 pm in diameter The term "calendered" as used herein may refer to a material which has undergone a calendering step. For example, by passing the material through the nip of a pair of rollers, wherein one or both of the rollers are heated. The calender rollers typically impart heat and pressure onto the material causing at least the outer surface of the filaments or fibres to soften and allowing them to bond to one another. In this way, the calendering process increases the consolidation of the material. The rollers may be plain, smooth and/or patterned.

It is to be appreciated that the various embodiments may be applied to each of the aspects without departing from the scope of the invention. For example, any features of the first aspect may be equally applicable with the second, third, fourth, fifth or sixth aspects. However, for the sake of brevity, these embodiments have not been repeated in relation to each aspect.

BRIEF DESCRIPTION OF DRAWINGS

These and other aspects of the present invention will now be described by way of example only, with reference to the accompanying drawings.

Figure 1 shows a schematic representation of a side view of a laminated fabric comprising a first layer of a meltblown material laminated to a second layer of spunbond material according to an embodiment of the present invention; Figure 2 shows a schematic representation of a side view of a laminated fabric comprising a first layer of a meltblown material laminated to a second and third layer of spunbond material according to an embodiment of the present invention; Figure 3 shows a schematic cross-sectional representation of an unsupported roof; Figure 4 shows a schematic cross-sectional representation of a fully supported or sarked roof; Figure 5 shows a perspective view of a laminated fabric according to one embodiment of the present invention; Figures 6a shows a microscopy image of a typical meltblown layer; and Figure 6b shows a microscopy image of a finer fibred meltblown material according to one embodiment of the present invention.

DETAILED DESCRIPTION OF DRAWINGS

Referring to Figure 1, there is shown a laminated fabric 10 according to a first embodiment of the present invention. The fabric 10 comprises a first layer of a meltblown material 12 laminated to a second layer of spunbond material 14. The meltblown material 12 has a basis weight less than 35g/m2 and is formed of fibres having a fibre diameter less than approximately 2.5 pm.

A second embodiment of the present invention is shown in Figures 2 and 5. In this embodiment, the first layer of meitblown material 22 is sandwiched between the second and third layers of spun-bond material (24, 26). The second and third layers of spunbond material (24, 26) act as an abrasion resistant, durable and protective cover for the meltblown material 22.

In these and other embodiments of the present invention, the meltblown material layer (12, 22) is laminated to the layer(s) of spunbond material (14, 24, 26) by passing the sheet materials simultaneously through, for example, a point bonding calendering process. In this process, which is known in the art, a combination of heat and pressure is applied in an intermittent pattern known as point bonding. An example pattern is illustrated most clearly in Figure 5. The area of such bond points is typically 5% to 40% of the total area of the bonded materials and may preferably be in the range 15%to20%.

Laminated fabrics according to these and other embodiments of the present invention are air permeable and vapour permeable. Thus, air and vapour are able to pass through the membrane as illustrated by arrows B' in Figure 5. As is also illustrated on Figure 5, laminated fabrics according to embodiments of the present invention offer improved water hold-out properties meaning that the fabric resists the passage of water droplets (as shown by arrows A').

Laminated fabrics according to embodiments of the present invention may be used as building materials, for example, as roofing underlays. Typical roof constructions for cold' unoccupied roof spaces are shown in Figures 3 and 4. Figure 3 shows an unsupported roof, wherein the underlay, for example a laminated fabric 10,20) is draped between the rafters 30. Battens 42 are placed on top of the underlay and the tiles or slates 40 are secured onto these battens.

An alternative construction is a fully supported or sarked roof as is shown in Figure 4. In this type of construction, boards or sheets 44 are placed on the rafters 30.

These boards or sheets 44 are commonly known in the art as sarking and are typically made out of timber or fibreboard, such as oriented strand board (OSB). An underlay, such as a laminated fabric 10,20, is laid directly onto the sarking 44. Tiles or slates 40 are secured directly through the underlay to the sarking (as shown in Figure 4).

Alternatively battens may be laid on top of the underlay and secured to the sarking and the tiles or slates secured to these battens.

Examples falling within the scope of the invention will now be described.

Example 1

A polypropylene meltblown layer of basis weight 30 g/m2 and an average fibre diameter of 2.3 pm was provided. The polypropylene layer was pre-compressed and then thermally laminated using a point-bonding calendering process at a temperature of 120 -170 °C and a pressure of 30 -150 N/mm to a second polypropylene spunbond layer having a basis weight of 90 g/m2 and a third polypropylene spunbond layer having a basis weight of 50 g/m2.

Comparative Example 1 A polypropylene meltblown layer having a basis weight of 35 g/m2 and an average fibre diameter of 2.8 pm was provided. The propylene meltblown layer was pre-compressed and then thermally laminated using a point-bonding calendering process to a second polypropylene spunbond layer having a basis weight of 90 g/m2 and a third polypropylene spunbond layer having a basis weight of 50 g/m2 as described for Example 1.

The properties of the meltblown layers and the laminated fabrics were tested in accordance with the following procedures and are set out in Tables 1 and 2.

Hydrostatic Head Hydrostatic head is a measurement of the ability of a fabric to resist water penetration. It is the pressure, measured in cm H20, required to force water through the fabric. The value quoted is the pressure reached when 3 drops of water have penetrated the fabric. Hydrostatic head was measured according to the test method as set out in 85 EN 20811:1992 Textiles -Determination of resistance to water penetration -Hydrostatic pressure test.

Air permeability Air permeability may be quantified by measuring the quantity of air that passes through a fixed area of fabric at a set pressure drop across the fabric. The air permeability of the Example fabrics was measured using the test method EDANA14O.2-99 (developed by The European Disposables & Nonwovens Association (EDANA)). In this test method, the quantity of air (measured in lIm2Is) passing through a 20cm2 of fabric is measured at a pressure drop of 200 Pa.

Tensile Strength The tensile strength and elongation properties of the laminate fabrics in the machine-and cross-directions (MD and CD) was measured using the test method EDANA (European Disposables and Nonwovens Association) method 20.2-89.

Fibre Diameter Fibre diameter may be measured using microscopy techniques.

Table 1 -Meltblown Properties Property Units Meltblown ________________________ __________ Comparative Example 1 Example 1 Meltblown layer Standard' Fine fibred' ________________________ __________ Polypropylene Polypropylene Basis weight g/m2 35 30 Air permeability l/m2/s 300 280 Hydrostatic head cm 75 84 Tensile MD/CD N/Scm 26/21 23/16 Elongation MD/CD % 45/60 27/44 Filament Diameter pm 2.8 2.3 MD = Machine Direction; CD Cross Direction Table 2 -Laminate Properties Property Units Laminated fabric Basis weight g/m2 175 170 Spunbondlayer2 g/m2 90 90 ________________________ __________ Polypropylene spunbond Polypropylene spunbond Meltblown layer 1 g/m2 35 30 Comparative Example 1 Example 1 ________________________ __________ Standard' fine fibred' Spunbondlayer3 g/m2 50 50 ________________________ __________ Polypropylene spunbond Polypropylene spunbond Hydrostatic Head cm 115 121 Air permeability gIm2 61 62 Surprisingly, the data illustrates that the laminated fabric of Example 1 showed an improved water hold-out (hydrostatic head) in comparison to the laminated fabric of Comparative Example 1, despite comprising a lighter weight meltblown layer. The data shows that despite a 14% reduction in the weight of the meltblown, the laminated fabric of Example 1 demonstrates improved water hold-out and air permeability.

The laminated fabric incorporating the finer fibred' meltblown of Example 1 provides an improved level of water hold-out together with the benefits of maintaining air permeability.

Claims

<claim-text>CLAIMS1. A laminated fabric, such as a rooting underlay, comprising: a first layer of meltblown material laminated to a second layer of spunbond material; wherein the meltblown material has a basis weight less than approximately 35 g/m2; and wherein the meltblown material is formed of fibres having a fibre diameter less than approximately
2.5 pm.</claim-text> <claim-text>2. A laminated fabric according to claim 1, wherein the laminated fabric comprises an air permeable laminate and/or a vapour permeable laminate, such as a water vapour permeable laminate.</claim-text> <claim-text>3. A laminated fabric according to any preceding claim, wherein the laminated fabric comprises a third layer of spunbond material, optionally wherein the first layer of meltblown material is sandwiched between the second and third layers of spun-bond material.</claim-text> <claim-text>4. A laminated fabric according to any preceding claim, wherein the laminated fabric has a hydrostatic head greater than 100cm, greater than 110cm, greater than 115cm or greater than 120cm.</claim-text> <claim-text>5. A laminated fabric according to any preceding claim, wherein the laminated fabric has a hydrostatic head between 100cm and 150cm, between 110cm and 140cm, or between 115cm and 130cm.</claim-text> <claim-text>6. A laminated fabric according to any preceding claim, wherein prior to lamination, the first layer of meltblown material has a hydrostatic head of greater than 60cm, greater than 70cm, greater than 75cm, or greater than 80cm.</claim-text> <claim-text>7. A laminated fabric according to any preceding claim, wherein the laminated fabric has an air permeability greater than 40 l/m2/s, greater than about 50 l/m2/s, or greater than about 55 l/m2/s, or greater than about 60 l/m2/s.</claim-text> <claim-text>8. A laminated fabric according to any preceding claim, wherein the laminated fabric has an air permeability between 20 l/m2/s and 100 l/m2/s, between 40 l/m2/s and l/m2/s, for example between 50 l/m2/s and 70 l/m2/s.</claim-text> <claim-text>9. A laminated fabric according to any preceding claim, wherein the first layer of meltblown material has a basis weight between 10 g/m2 and 35 g/m2 or between 15 g/m2 and 35 g/m2, or between 20 g/m2 and 35 g/m2, or between 25 g/m2 and 34 g/m2.</claim-text> <claim-text>10. A laminated fabric according to any preceding claim, wherein the first layer of meltblown material is formed of fibres having a fibre diameter less than approximately 2.Spm, or less than 2.4pm.</claim-text> <claim-text>11. A laminated fabric according to any preceding claim, wherein the fibres in the meltblown material have a diameter between 1pm and 2.Spm, or between 1.Spm and 2.4pm, or between 2.2 and 2.4 pm.</claim-text> <claim-text>12. A laminated fabric according to any preceding claim, wherein the second and/or third layer(s) of spunbond material may have a basis weight between 15 and 150 g/m2, or between 40 and 100 g/m2.</claim-text> <claim-text>13. A laminated fabric according to any preceding claim, wherein the first layer of meltblown material and the second and third layers of spunbond material comprise polymers selected from polyolefinic polymers such as polyethylene and polypropylene homopolymers and co-polymers thereof and mixtures of homopolymers and co-polymers.</claim-text> <claim-text>14. A laminated fabric according to any preceding claim, wherein the first layer of meltblown material and the second and/or third layers of spunbond material comprise polypropylene.</claim-text> <claim-text>15. A laminated fabric according to any preceding claim, wherein the laminated material comprises additives selected from hydrophobic melt additives and the like, for example an organic fluorocarbon derivative, UV absorbing additives, flame retardants, pigments and plasticisers, and the like.</claim-text> <claim-text>16. A method of making a laminated fabric, such as a roofing underlay, comprising: providing a first layer of meltblown material having a basis weight less than approximately 35 g/m2 and being formed of fibres having a fibre diameter less than approximately 2.5 pm; laminating the first layer of meltblown material to at least a second layer of spunbond material to provide a laminated fabric.</claim-text> <claim-text>17. A method of making a laminated fabric, such as a roofing underlay, comprising: laminating a first layer of meltblown material to at least a second layer of spunbond material to provide a laminated fabric; wherein the meitblown material has a basis weight less than approximately 35 g/m2 and is formed of fibres having a fibre diameter less than approximately 2.5 pm.</claim-text> <claim-text>18. A method of making a laminated fabric according to claim 160117, wherein the method comprises laminating the first layer of meltblown material to a third layer of spunbond material.</claim-text> <claim-text>19. A method of making a laminated fabric according to any of claims 16 to 18, wherein laminating comprise passing the first, second and/or third layers of material through calender rollers, preferably through heated calender rollers and optionally under pressure.</claim-text> <claim-text>20. A method of making a laminated fabric according to any of claims 16 to 19, wherein laminating meltblown sheets is effected by passing the sheet materials simultaneously through a point bonding calendering process.</claim-text> <claim-text>21. A method of making a laminated fabric according to claim 20 wherein the area of bond points is 5% to 40% or 15% to 20% of the total area of the bonded materials.</claim-text> <claim-text>22. A method of making a laminated fabric according to any of claims 16 to 21, wherein the method comprises providing a pre-compressed first layer of meltblown material.</claim-text> <claim-text>23. A roof which comprises a laminated fabric according to any preceding claim.</claim-text> <claim-text>24. A roof according to claim 23, where the roof is an unsupported or fully supported roof.</claim-text> <claim-text>25. A building with a roof comprising a laminated fabric according to any preceding claim.</claim-text> <claim-text>26. Use of a laminated fabric according to any preceding claim as a building material, such as a roofing underlay.</claim-text> <claim-text>27. A laminated fabric substantially as described herein with reference to the accompanying drawings.</claim-text> <claim-text>28. A method of making a laminated fabric substantially as described herein with reference to the accompanying drawings.</claim-text> <claim-text>29. Use of a laminated fabric substantially as described herein with reference to the accompanying drawings.</claim-text>