GB2518055A

GB2518055A - Improved fabric

Info

Publication number: GB2518055A
Application number: GB1414995.9A
Authority: GB
Inventors: David Avril; Keith Galloway; Robert Murphy
Original assignee: Don and Low Ltd
Current assignee: Don and Low Ltd
Priority date: 2014-08-22
Filing date: 2014-08-22
Publication date: 2015-03-11
Anticipated expiration: 2034-08-22
Also published as: GB2525103A; GB2525103B; GB201510856D0; GB201414995D0; GB2518055B

Abstract

A laminated fabric comprises a first meltblown layer 22 and a second spunbond layer 24 and optionally a third spunbond layer 26. The average basis weight of the second layer 24 is less than 80 g/m2 and the laminated fabric has a hydrostatic head greater than 90 cm. In use the second layer 24 may form the outer facing surface and the third layer 26 may form the inner facing surface of a roofing underlay. The average basis weight of the third layer 26 is preferably 50 g/m2 or less. Each layer may include a hydrophobic additive. In its weakest direction the fabric may have a tear strength of at least 100 N/5cm and in its machine direction a nail tear strength of at least 90 N. The fabric may have a wind uplift pressure of at least 820 Pa and an air permeability of more than 50 l/m/s2. The layers may be united by point bond calendering using heat and pressure to give a 5% to 40% bond area.

Description

IMPROVED FABRIC

FIELD OF INVENTION

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

The laminated fabric may be suitable for a variety of applications. For example, laminated fabrics of the present invention may be used as building materials, such as roofing underlay. The invention may relate to lighter-weight gas and vapour 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 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 water from the roof space beneath the underlay. Air permeable and vapour permeable underlays may be described as breathable' 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' roofs -where the insulation is at rafter level with the roofspace itself being occupied, and cold' roof spaces -where the insulation is laid on the floor of the roofspace and the roofspace is unoccupied.

Traditionally, unwanted moisture is evacuated from cold' roof spaces via the introduction of mechanical vents, typically at the eaves and/or 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 roof 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 floor of the roofspace, thus reducing the efficiency of the insulation.

The use of an air and vapour permeable roofing underlay as an alternative to mechanical ventilation may reduce heat losses and improve the thermal efficiency of a property, whilst at the same time reducing the risk of condensation. The superior performance of air and vapour permeable fabrics when compared to air barrier/vapour permeable materials to reduce condensation in energy efficient 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, e.g. where traditional mechanical vents are eliminated from the roof 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 EP 0 742 305 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.

Water hold-out performance of a non-woven laminated fabric is generally quantified using hydrostatic head which measures the resistance of the fabric to water penetration under pressure. As water is forced though the laminated fabric, the laminated fabric flexes, or domes, under the increasing water pressure.

The water hold-out performance of non-woven laminated fabrics based on co-extruded or monolayer films comprising a plurality of micropores or monolithic films (e.g. vapour permeable/air barrier roofing underlays) remains unchanged as the laminated fabric flexes or domes. By contrast, as a laminated fabric comprising a meltblown layer (e.g. an air and vapour permeable laminated fabric) flexes and starts to dome under the increasing water pressure, the pores between the meltblown filaments (or fibres) open up and more readily allow water to pass through. Conventionally, one or more heavier spunbond layers are used to support the meltblown layer to reduce the effect of this phenomenon. The use of such heavier supporting spunbond layers is intended to increase the rigidity of the laminated fabric to increase its resistance to doming under increasing water pressure.

In addition to a sufficient water hold-out performance, laminated fabrics for use as roofing underlays should also be sufficiently robust and strong to withstand manual handling and builders walking upon it during installation. Heavier spunbond layers are generally used to support the relatively delicate meltblown layer and provide the necessary strength and robustness.

Moreover, laminated fabrics for use as roofing underlays should show sufficient wind uplift performance. Wind uplift is a measure of the extent to which the fabric will balloon' under air pressure, once installed on a roof. Roofing underlays that balloon' more easily may have the potential to dislodge a slate or tile when subjected to an air current from underneath, once installed on a roof. The greater the weight of the laminated fabric appears to increase the resistance of the fabric to ballooning" and to improve the wind uplift performance.

However, the use of heavier spunbond layers may lead to heavier composite fabrics which are more expensive and less easy to handle when in use on a building site.

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 invention there is provided a laminated fabric, such as a building or construction fabric, the laminated fabric comprising or solely consisting of: a first meltblown layer laminated to at least a second and a third spunbond layer, wherein the first layer is sandwiched between the second and third layers to provide a spunbond-meltblown-spunbond (SMS) laminated fabric, wherein the average basis weight of the second spunbond layer is between 50 and 80 g/m2, and the laminated fabric has a hydrostatic head greater than 90 cm.

Beneficially, in use, laminated fabrics according to embodiments of the present invention may be used as building or construction materials, for example, as roofing underlays.

Advantageously, roofing underlays comprising laminated fabrics of the invention may be used in cold' roofspaces, such as cold non-ventilated roofspaces. By a cold roofspace, it is meant where roofing insulation is provided, e.g. laid on the floor of the roofspace and the roofspace is unoccupied. Such roofs are particularly found in the UK. As used herein, non-vented or non-ventilated roofs are roofs which do not comprise mechanical vents, for example, a roof which does not comprise mechanical vents at eaves or ridges thereof. Such roofs generally rely entirely on the breathability of the roofing underlay for evacuation of moisture from the roofspace. As used herein, a pitched roof may be any roof which comprises a sloping surface, or any roof in which two or more roof surfaces are pitched at an angle, e.g. not a flat roof.

The laminated fabrics may provide fabrics with an overall reduced weight whilst maintaining a number of performance parameters associated with the use of the fabric in building and construction applications. In particular, the use of a lighter weight spunbond layer in the laminated fabrics of embodiments of the present invention may enable the provision of lighter weight laminated fabrics for use in building or construction, e.g. as a roofing underlay. For example, laminated fabrics of the present invention may show sufficient levels of water hold-out, tensile strength and/or wind uplift performance notwithstanding a reduced weight of at least one spunbond layer.

The reduced weight of the spunbond layer(s) in the laminated fabric may assist in the provision of lighter weight fabrics facilitating ease of handling, e.g. during installation.

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

Laminated fabrics of the invention may be resistant to the passage of water droplets and may have the ability to hold-out water. Levels of water hold-out may be quantified by hydrostatic head measurements. The laminated fabric may have a hydrostatic head of at least 90cm, or at least 95cm. The laminated fabric may have a hydrostatic head between 90cm and 150cm, or between 90cm and 120cm, or between 95cm and 105cm. The laminated fabric may have a hydrostatic head of approximately 95cm.

The average basis weight of the second spunbond layer may be at least 60 gIm2, or may be between 60 g/m2 and 80 g/m2, or may be between 65 and 75 g/m2.

The average basis weight of the second spunbond layer may be approximately 50 g/m2 or 70 g/m2. As used herein, basis weight may refer to the mass of a unit area of fabric.

In certain embodiments of the present invention, the second spunbond layer may comprise an outer facing surface. For example, when used as a construction fabric (e.g. a roofing underlay), the second spunbond layer may be arranged to face an external or outside environment.

The average basis weight of the third spunbond layer may be 50 gIm2 or less, or may be between 20 g/m2 and 50 g/m2.

In some embodiments of the present invention, the third spunbond layer may comprise an inner facing surface. For example, when used as a construction fabric (e.g. a roofing underlay), the third spunbond layer may be arranged to face an internal or inside environment (e.g. an inside of a building).

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 these and other embodiments of the present invention, the combined average basis weight of the second and third layers of spunbond material may be less than 125 g/m2, less than 120 g/m2, or less than 110 g/cm2. In some embodiments, the combined average basis weight of the second and third layers of spunbond material may be between 60 g/m2 and 120 g/m2, or between 70 and 110 g/cm2.

The first meltblown layer may have a basis weight between 10 g/m2 and 60 or between 20 g/m2 and 50 g/m2 or between 30 g/m2 and 40 g/m2. For example, the first meltblown layer may have a basis weight of approximately 35 g/m2.

In these and other embodiments, a laminated fabric according to the present invention comprising a reduced weight of spunbond material advantageously provides comparable levels of water hold-out performance when compared to a heavier laminated fabric comprising a meltblown layer of the same basis weight.

In certain embodiments, the laminated fabric may have a tensile strength of at least 100N/5cm, at least 11ON/5cm, at least 125N/5cm, at least 150N/Scm, or at least 170N/Scm in the weakest direction. In some embodiments, the weakest direction of the laminated fabric in terms of tensile strength may be the cross direction (CD).

In these and other embodiments of the invention, the laminated fabric may have a tensile strength of at least 200N/Scm, at least 220N/Scm, at least 250N/Scm or at least SOON/Scm in the machine direction (MD).

As used herein, "cross direction" may refer to the width direction, within the plane of a fabric, that is perpendicular to the direction in which the fabric is being produced by the machine.

As used herein, "machine direction" may refer to the long direction within the plane of a fabric, that is the direction in which the fabric is being produced by the machine.

The laminated fabric may have a nail tear strength of at least SON in the machine direction. The laminated fabric may comprise a nail tear strength of at least 90N, at least 120N or at least 150N in the machine direction. The laminated fabric may comprise a nail tear strength between 80N and 180N, or between 90N and 170N in the machine direction. In some embodiments, the weakest direction of the laminated fabric in terms of nail tear strength may be the machine direction (MD).

The laminated fabric may comprise a nail tear strength of at least lOON, at least liON, at least 140N or at least 200N in the cross direction. The laminated fabric may comprise a nail tear strength of between lOON and 300N, or between liON and 250N in the cross direction.

Guidance on strength requirements for roofing underlays may generally be provided by national regulating bodies, e.g. the French Agrement body, Centre Scientifique et Technique du Bâtiment (CSTB) and the national Agrément body in the Netherlands, Intron. For example, CSTB indicate minimum performance requirements for three classifications of underlay, Ri, R2 and R3 as are shown in Table 1.

Underlay Minimum Tensile Strength in the Minimum Nail Tear Strength Classification Weakest Direction (N/5cm) (N) Ri 100 75 R2 200 150 R3 300 225 Table 1 CSTB -Minimum performance requirements for a roofing underlay To meet the requirements of the lowest performance category in France (Ri), a roofing underlay should have a minimum tensile strength of 100N/5cm and a minimum nail tear strength of 75N (in the weakest direction). In the Netherlands, a tensile strength of 125N/Scm has been indicated as the minimum required for a roofing underlay (in the weakest direction). Tensile strength may be measured in accordance with the method outlined in BS EN 12311-1 and nail tear strength may be measured in accordance with the method outlined in BS EN 12310-1.

The laminated fabric may have a tensile strength and/or a nail tear strength greater than the minimum performance requirements of a national regulating body, such as the CSTB and/or Intron.

Laminated fabrics comprising a reduced weight of spunbond may show an increased flexibility. When used as a roofing underlay, such laminated fabrics may have a tendency to balloon' more easily, e.g. once installed on a roof. Consequently, when subjected to a wind load, such laminated fabrics may have an increased tendency to dislodge a slate or tile.

Wind uplift performance may be measured using the wind uplift' test method described in 85 5534, Code of Practice for Slating and Tiling. This test method measures the wind uplift pressure required to cause the underlay to balloon by 35mm.

The greater the wind uplift pressure required, the more resistant the laminated fabric may be to ballooning'. BS 5534 indicates that a roofing underlay should withstand a wind uplift pressure of 820 Pa to meet the minimum requirement for an unsupported roof at maximum batten spacing in Zone 1 of the UK.

The laminated fabric may withstand a wind uplift pressure of at least 820 Pa.

The laminated fabric may withstand a wind uplift pressure of at least 840 Pa, at least 900 Pa or at least 950 Pa.

The laminated fabric may be gas and/or vapour permeable, e.g. water vapour permeable.

The laminated fabric may have an air permeability greater than about 50 l/m2/s, greater than about 60 l/m2/s, greater than about 70 l/m2/s, greater than about 100 l/m2/s or greater than about 120 l/m2/s. The laminated fabric may have an air permeability between 50 l/m2/s and 150 l/m2/s, between 60 l/m2/s and 140 l/m2/s or between 70 l/m2/s and 130 l/m2/s.

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.

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

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 stabilising 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/ol added to the meltblown material, include additives such as flame retardants, pigments and plasticisers, and the like.

Preferably, the laminated fabric may comprise hydrophobic additives, optionally wherein the hydrophobic additives are present in each layer of the laminated fabric.

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

The laminated fabric may have been laminated by thermal point bond calendering.

According to a second aspect of the present invention there is provided a method of making a laminated fabric comprising laminating a first layer of meltblown material to at least a second layer of spunbond material and a third layer of spunbond material to provide a spunbond-meltblown-spunbond (SMS) laminated fabric having a hydrostatic head greater than 90 cm; wherein the average basis weight of the second spunbond layer is between 50 and 80 g/m2.

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 120 00 and 170 °C. Pressures between 30 N/mm and 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 third layers of spunbond material, may be effected by passing the sheet materials simultaneously through, for example, a calendering process, such as 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%.

Laminating a meltblown sheet to a second and third layer of spunbond material may cause the layers to be thermally bonded to one another. Thermal bonding may be effected when the materials in each of the meltblown and spunbond layers are compatible. For example, the materials in each layer may be chemically compatible and/or may have broadly similar softening and/or melting temperatures. In such cases, autogenous bonding between the layers may occur under conditions of appropriate heat and pressure. For example, the layers may be autogenously bonded to form the laminated fabric.

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 melting of fibres and/or filaments in the material.

According to a third aspect of the invention there is provided a building or building structure comprising a laminated fabric according to the first aspect or made according to the method of the second aspect of the present invention.

A roof of the building or building structure may comprise the laminated fabric.

The roof may be an unsupported roof, such as an unsupported cold pitched roof and/or a non-vented roof, e.g. a non-vented cold pitched roof. Alternatively the roof may be a fully supported (sarked) roof.

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.

A non-vented roof is one in which there are no mechanical vents incorporated into the roof design, e.g. no mechanical vents at the eaves or ridges of the 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').

According to a fourth aspect of the present invention there is provided a panel comprising a laminated fabric as defined in the first aspect or made according to the method of the second aspect.

The panel may be a building or construction panel. The panel may be a prefabricated building or construction panel.

According to a fifth aspect of the present invention there is provided a use of a laminated fabric, as defined in the first aspect or made according to the method of the second aspect, as a building material.

In certain embodiments, the laminated fabric may be used as a roofing underlay. For example, the laminated material may be used on an unsupported roof e.g. a non-vented cold pitched roof, or, alternatively, it may be used on a fully supported (sarked) roof, such as a roofing underlay, e.g. as a roofing underlay on an unsupported roof.

In certain embodiments, the laminated fabric may be used in pre-fabricated building panels or construction elements. For instance, the laminated fabric may be used in prefabricated roofing panels. Prefabricated panels may be made remotely (e.g. in a factory) prior to being transported to a building site. Generally, the demands on a construction fabric, such as a roofing underlay, may be less where a fabric has been applied to a panel remotely (e.g. in a factory) rather than applied on site. For instance, the laminated fabrics in such prefabricated panels may be exposed to an outside environment for a shorter period of time. Additionally or alternatively, laminated fabrics comprised in prefabricated panels may require less or no manipulation and/or handling onsite. Beneficially, lighter weight laminated fabrics according to embodiments of the invention may have sufficient performance parameters (e.g. hydrostatic head and/or tensile strength) for use in such prefabricated building panels or construction elements.

Advantageously, the lighter weight laminated fabrics of invention may allow the provision of lighter weight prefabricated building panels.

According to a sixth aspect of the present invention there is provided a laminated fabric, such as a building or construction fabric, comprising: a first meltblown layer laminated to at least a second spunbond layer, wherein the average basis weight of the second layer is less than 80 g/m2, and the laminated fabric has a hydrostatic head greater than 90 cm.

The second spunbond layer may comprise an outer or outer facing layer.

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, which are: 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; and Figure 5 shows a perspective view of a laminated fabric according to one embodiment of the present invention.

DETAILED DESCRIPTION OF DRAWINGS

Referring to Figure 1, there is shown a laminated fabric 10 comprising a first layer of a meitblown material 12 laminated to a second layer of spunbond material 14 according to an embodiment of the invention.

A second embodiment of the present invention is shown in Figures 2 and 5. In this embodiment, the first layer of meltblown 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. The second spunbond layer 26 has an average basis weight between 50 g/m2 and 80 g/m2.

In these and other embodiments of the present invention, the meltblown material layer (12, 22) is laminated to the layers 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% to 20%.

Laminated fabrics according to these and other embodiments of the present invention are air permeable and water vapour permeable. Thus, air and water 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 provide levels of water hold-out 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.

Roofing underlays have previously been available as heavier weight laminated SMS fabrics having a total basis weight of at least around 175 g/m2. One such fabric is described below as Comparative Example 1.

Laminated fabrics according to embodiments of the invention have been made using the same meltblown layer as used in Comparative Example 1 but these fabrics comprise a lesser weight of spunbond. These are described below as Examples 1, 2 and 3. Examples falling within the scope of the invention will now be described.

Example 1

A polypropylene meltblown layer of basis weight 35 g/m2 was 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 50 g/m2 and a third polypropylene spunbond layer having a basis weight of 20 g/m2.

Example 2

A polypropylene meltblown layer having a basis weight of 35 g/m2 was thermally laminated using a point-bonding calendering process to a second polypropylene spunbond layer having a basis weight of 50 g/m2 and a third polypropylene spunbond layer having a basis weight of 50 g/m2 as described for

Example 1.

Example 3

A polypropylene meltblown layer having a basis weight of 35 g/m2 was thermally laminated using a point-bonding calendering process to a second polypropylene spunbond layer having a basis weight of 70 g/m2 and a third polypropylene spunbond layer having a basis weight of 50 g/m2 as described for

Example 1.

Comparative Example 1 A polypropylene meltblown layer having a basis weight of 35 g/m2 was 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.

Various properties of the laminated fabrics were tested in accordance with the methods outlined below. The results are shown in Table 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 BS EN 20811:1992 Textiles -Determination of resistance to water penetration -Hydrostatic pressure test.

Tensile Strength The tensile strength of the laminated fabric was measured in accordance with the test method as set out in BS EN 12311-1 (Flexible sheets for waterproofing.

Determination of tensile properties).

Nail Tear Strength The nail tear strength of the laminated fabric was measured in accordance with the test method as set out in BS EN 12310-1 (Flexible Sheets for Waterproofing -Determination of Resistance to Tearing (Nail Shank)).

Wind Uplift Wind uplift is a measure of the extent to which a fabric will balloon', once installed on a roof, e.g. when subjected to a wind load. Wind uplift was measured in accordance with the test method set out in BS 5534, Code of Practice for Slating and Tiling. This test provides a measurement of the wind uplift pressure required to cause the underlay to balloon' by 35mm.

A greater wind uplift pressure indicates a fabric is more resistant to ballooning'.

The test method BS 5534 indicates that a roofing underlay should withstand a minimum wind uplift pressure of 820Pa to meet the minimum requirement for an unsupported roof at maximum batten spacing in Zone 1 of the UK.

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 fabrics was measured using the test method as set out in EN ISO 9,237 (Textiles -Determination of the permeability of fabrics to air, equivalent to the test method as set out in DIN 53,887). In this test method, the quantity of air (measured in l/m2/s) passing through a 20cm2 of fabric is measured at a pressure drop of 200 Pa.

Property Unit Example Example Example Comparative

1 2 3 Example 1

Laminate Weight g/m2 105 135 155 175 Laminate Composition g/m2 50 50 70 90 Outer spunbond layer g/m2 35 35 35 35 Meltblown layer g/m2 20 50 50 50 Inner spunbond layer Hydrostatic head cm 95 95 98 110 MD tensile strength N/Scm 225 282 319 340 CD tensile strength N/Scm 114 153 185 230 MD nail tear strength N 90 128 168 180 CD nail tear strength N 115 149 245 175 Wind uplift pressure Pa >820 >820 >820 1,060 Air permeability l/m'/s 121 79 63 61 Table 2-Laminate Properties Discussion Hydrostatic Head (Water Hold-Out): The SMS laminated fabrics of Examples 1, 2 and 3 all have a hydrostatic head of at least 95cm. A hydrostatic head of 95cm will generally provide a satisfactory water hold out for roofing underlay applications. The second spunbond layer of each of these Example fabrics has an average basis weight of at least 50g/m2. Tests have indicated that SMS laminated fabrics in which the second spunbond layer has an average basis weight of less than 50 g/m2 generally provide lower levels of water hold-out, which may be insufficient for general roofing underlay applications.

Tensile Strength: The results shown for Examples 1, 2 and 3 in table 2, indicate that: * The SMS laminates of Examples 1, 2 and 3 exceed the minimum tensile strength and nail tear strength requirements of France.

* The SMS laminates of Examples 2 and 3 also exceed the minimum tensile strength requirements of The Netherlands.

The results therefore indicate that the minimum requirements of many European regulatory bodies can be met by the example laminated fabrics, comprising a reduced weight of spunbond.

Air Permeability: The data illustrates that the laminated fabrics of Examples 1, 2 and 3 show improved or comparable levels of air permeability in comparison to the laminated fabric of Comparative Example 1. These levels of air permeability will enable these fabrics to effectively evacuate water vapour. Thus, when used in roofspaces, laminated fabrics of the invention can reduce the risk of condensation and may find application in non-vented cold pitched roofs.

Wind Uplift Pressure: The results indicate that the laminated fabrics of Examples 1, 2 and 3 withstand a wind uplift pressure of 820 Pa. Thus, a laminated fabric comprising an outer spunbond layer having an average basis weight of at least 50 g/m2 meets the wind uplift minimum requirement for an unsupported roof at maximum batten spacing in Zone 1 of the UK as indicated in BS 5534.

Manual handling: A roll of a typical SMS laminated fabric such as Comparative Example 1 (having a total basis weight of 175 g/m2) is generally supplied in 50m length by 1.5m wide rolls.

A finished roll of such dimensions has a weight of approximately 13.1kg. A roll (having the same dimensions) of the laminated fabric of Example 1 has a weight of approximately 7.9 kg, providing a weight reduction of 40%.

Therefore, the laminated fabrics of Examples 1, 2 and 3 enable the provision of lighter weight laminated fabrics whilst maintaining a number of performance parameters associated with building and construction applications.

Claims

CLAIMS1. A laminated fabric, such as a building or construction fabric, the laminated fabric solely consisting of: a first meltblown layer laminated to at least a second and a third spunbond layer, wherein the first layer is sandwiched between the second and third layers to provide a spunbond-meltblown-spunbond (SMS) laminated fabric, wherein the average basis weight of the second spunbond layer is between 50 and 80 g/m2, and the laminated fabric has a hydrostatic head greater than 90 cm.
2. A laminated fabric according to claim 1, wherein the second spunbond layer comprises an outer facing surface, and/or wherein the third spunbond layer comprises an inner facing surface.
3. A laminated fabric according to any preceding claim, wherein the average basis weight of the second spunbond layer is at least 60 g/m2, or between 60 g/m2 and 80 or between 65 and 75g1m2.
4. A laminated fabric according to any preceding claim, wherein the average basis weight of the third spunbond layer is 50 g/m2 or less, or between 20 g/m2 and 50 g/m2.
5. A laminated fabric according to any preceding claim, wherein the combined total average basis weight of the second and third layers of spunbond material is less than 125 g/m2, less than 120 g/m2, less than 110 g/m2, or between 60 g/m2 and 120 or between 70 g/m2 and 110 g/m2.
6. A laminated fabric according to any preceding claim, wherein the laminated material comprises hydrophobic additives, optionally wherein the hydrophobic additives are present in each layer of the laminated fabric.
7. A laminated fabric according to any preceding claim, wherein the laminated fabric has a tensile strength of at least 100 NI5cm, at least 110 N/Scm, at least 125 N/Scm, at least 150 N/5cm, or at least 170 N/5cm in the weakest direction.
8. A laminated fabric according to any preceding claim, wherein the laminated fabric has a nail tear strength of at least 90 N, at least 120 N, or at least 150 N in the machine direction
9. A laminated fabric according to any preceding claim, wherein the laminated fabric withstands a wind uplift pressure of at least 820 Pa.
10. A laminated fabric according to any preceding claim, wherein the laminated fabric is gas and/or vapour permeable, e.g. water vapour permeable.
11. A laminated fabric according to any preceding claim, wherein the laminated fabric comprises an air permeability of greater than 50 l/m2/s, greater than about 60 l/m2/s, gleater than about 70 l/m2/s, greater than about 100 l/m2/s 01 gieater than about l/m2/s.
12. A laminated fabric according to any preceding claim for use as a building material, such as roofing underlay.
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.
14. A laminated fabric according to any preceding claim, wherein the first meltblown layer and the second and third spunbond layers comprise or consist of single component polypropylene filaments.
15. A laminated fabric according to any preceding claim, wherein the fabric is laminated by calendering, such as thermal point bond calendering.
16. A laminated fabric according to any preceding claim, wherein the first meltblown layer and the second and third spunbond layers are autogenously bonded.
17. A method of making a laminated fabric comprising: laminating a first layer of meltblown material to at least a second layer of spunbond material and a third layer of spunbond material to provide a spunbond-meltblown-spunbond (SMS) laminated fabric having a hydrostatic head greater than 90 cm; whelein the aveiage basis weight of the second spunbond layer is between 50 and 80 gIm2.
18. A method of making a laminated fabric according to claim 17, wherein laminating comprises passing the first, second and third layers of material through calender rollers, such as through heated calender rollers and optionally under pressure.
19. A method of making a laminated fabric according to any of claims 17 or 18, wherein laminating meltblown sheets to the second and third layer of spunbond material, is effected by passing the sheet materials simultaneously through a point bonding calendering process.
20. A method of making a laminated fabric according to claim 19, wherein the area of bond points formed by the point bonding calendering process is 5% to 40% or 15% to 20% of the total area of the bonded materials.
21. A building or building structure comprising a laminated fabric according to any of claims 1 to 16 or a laminated fabric made according to the method of any of claims 17to20.
22. A building or building structure according to claim 20 wherein a roof comprises the laminated fabric.
23. A panel comprising a laminated fabric according to any of claims 1 to 16 or a laminated fabric made according to the method of any of claims 17 to 20, such as a building or constiuction panel, e.g. a piefablicated building or construction panel.
24. Use of a laminated fabric, as defined in any of claims ito 16 or made according to the method of any of claims 17 to 20, as a building material, such as a roofing underlay, e.g. as a roofing underlay on an unsupported roof.
25. A laminated fabric, such as a building or construction fabric substantially as described herein with reference to the accompanying drawings.
26. A laminated fabric, such as a building or construction fabric, comprising: a first meltblown layer laminated to at least a second spunbond layer, wherein the average basis weight of the second layer is less than 80 g/m2, and the laminated fabric has a hydrostatic head greater than 90 cm.
27. A laminated fabric according to claim 26, wherein the second spunbond layer comprises an outer or outer facing layer.Amendments to the claims have been filed as followsCLAIMS1. A laminated fabric, such as a building or construction fabric, the laminated fabric solely consisting of: a first meltblown layer laminated to a second spunbond layer and to a third spunbond layer, wherein the first meltblown layer is sandwiched between the second and third spunbond layers to provide a spunbond-meltblown-spunbond (SMS) laminated fabric, wherein the average basis weight of the second spunbond layer is between 50 and 80 the combined total average basis weight of the second and third spunbond IC) layers is less than 125 g/m2, the laminated fabric is gas and vapour permeable, and the laminated fabric has a hydrostatic head greater than 90 cm.C2. A laminated fabric according to claim 1, wherein the second spunbond layer comprises an outer facing surface, and/or wherein the third spunbond layer comprises an inner facing surface.3. A laminated fabric according to any preceding claim, wherein the average basis weight of the second spunbond layer is at least 60 g/m2, or between 60 g/m2 and 80 or between 65 and 75g/m2.4. A laminated fabric according to any preceding claim, wherein the average basis weight of the third spunbond layer is 50 g/m2 or less, or between 20 g/rn2 and 50 g/m2.S. A laminated fabric according to any preceding claim, wherein the combined total average basis weight of the second and third spunbond layers is less than 120 g/m2, less than 110 g/m2, or between 60 g/m2 and 120 g/m2, or between 70 g/m2 and gIm2.6. A laminated fabric according to any preceding claim, wherein the fabric is laminated by calendering, such as thermal point bond calendering.7. A laminated fabric according to any preceding claim, wherein the laminated fabric has a tensile strength of at least 100 N/Scm, at least 110 N/Scm, at least 125 N/Scm, at least 150 N/Scm, or at least 170 N/5cm in the weakest direction. IC)8. A laminated fabric according to any preceding claim, wherein the laminated r o fabric has a nail tear strength of at least 90 N, at least 120 N, or at least 150 N in the O 15 machine direction 9. A laminated fabric according to any preceding claim, wherein the laminated fabric withstands a wind uplift pressure of at least 820 Pa.10. A laminated fabric according to any preceding claim, wherein the laminated fabric is water vapour permeable.11. A laminated fabric according to any preceding claim, wherein the laminated fabric comprises an air permeability of greater than 50 l/m2/s, greater than about 60 l/m2/s, greater than about 70 l/m2/s, greater than about 100 l/m2/s or greater than about l/m2/s.12. A laminated fabric according to any preceding claim for use as a building material, such as roofing underlay.13. A laminated fabric according to any preceding claim, wherein the first meltblown layer and the second and third spunbond layers comprise polymers selected from polyolefinic polymers such as polyethylene and polypropylene homopolymers and co-polymers thereof and mixtures of homopolymers and co-polymers.14. A laminated fabric according to any preceding claim, wherein the first meltblown layer and the second and third spunbond layers comprise or consist of single component polypropylene filaments. IC)15. A laminated fabric according to any preceding claim, wherein the laminated r o material comprises hydrophobic additives, optionally wherein the hydrophobic additives o 15 are present in each layer of the laminated fabric.16. A laminated fabric according to any preceding claim, wherein the first meltblown layer and the second and third spunbond layers are autogenously bonded.17. A method of making a laminated fabric comprising: laminating a first layer of meltblown material to at least a second layer of spunbond material and to a third layer of spunbond material to provide a spunbond-meltblown-spunbond (SMS) laminated fabric having a hydrostatic head greater than 90 cm; wherein the average basis weight of the second spunbond layer is between 50 and 80 g/m2, the combined total average basis weight of the second and third spunbond layers is less than 125 gIm2, and the laminated fabric is gas and vapour permeable.18. A method of making a laminated fabric according to claim 17, wherein laminating comprises passing the first meltblown layer and second and third spunbond layers of material through calender rollers, such as through heated calender rollers and optionally under pressure.19. A method of making a laminated fabric according to any of claims 17 or 18, wherein laminating the first meltblown layer to the second and third spunbond layers, is IC) effected by passing the layers simultaneously through a point bonding calendering process. rO 15 20. A method of making a laminated fabric according to claim 19, wherein the area of bond points formed by the point bonding calendering process is 5% to 40% or 15% to 20% of the total area of the bonded materials.21. A building or building structure comprising a laminated fabric according to any of claims ito 16 or a laminated fabric made according to the method of any of claims 17 to 20.22. A building or building structure according to claim 20 wherein a roof comprises the laminated fabric.23. A panel comprising a laminated fabric according to any of claims 1 to 16 or a laminated fabric made according to the method of any of claims 17 to 20, such as a building or construction panel, such as a prefabricated building or construction panel.24. Use of a laminated fabric, as defined in any of claims ito 16 or made according to the method of any of claims 17 to 20, as a building material, such as a roofing underlay, such as as a roofing underlay on an unsupported roof.25. A laminated fabric, such as a building or construction fabric substantially as described herein with reference to the accompanying drawings. IC) r