Same

Field of the Invention

The present invention relates to a waterproof, windproof, breathable and stretchable laminated composite material for use in, for example, protective clothing made by a process of binding woven or knitted fabrics to a hydrophilic or micro-porous membrane using an adhesive applied in a dot-matrix pattern.

Introduction and Background

Waterproof fabrics have been known in the art for many years as have breathable and stretchable fabrics. The art demonstrates various methods of combining these desirable qualities, such as those taught by US 3,953,566 and US 4,194,041. In general, waterproof materials have the disadvantage of restricting the ability of water vapour to pass through the material, which is to say that they are not breathable, and in general, breathable materials are not waterproof. Where a laminate is formed using the application of an adhesive to bind the layers of the laminate together, the breathabiliry of the laminate has been dependent on the breathability of the adhesive used when that adhesive is applied in an approximately continuous coating between the layers. While advances have been made in the art of creating waterproof, windproof and breathable fabric composites, as shown by US 5,244,716, those composites have limited elasticity and stretch, as is known from EP 0725574. They are not repeatedly stretchable to an appreciable degree without the failure or rupture of either the waterproofing layers or the breathable layers of these composite fabrics or the permanent deformation of the laminates comprising such composite fabrics or the de-lamination and separation of the layers of the laminates through the failure of the adhesives used to bind the layers together. Summary of the Invention

To overcome these problems, the present invention proposes a laminate comprised of a waterproof, windproof and breathable membrane placed between layers of breathable or insulating materials with adhesive applied in a dot-matrix pattern through a suitable process known in the art, such as screen printing or spraying, to either or both sides of the waterproof, windproof and breathable membrane to bind the layers together resulting in a composite laminate that is waterproof, windproof, breathable and stretchable.

The waterproof layer of the present invention is preferably provided by a non-porous hydrophilic membrane that is impenetrable to liquid water but that will allow water vapour to pass through it by osmosis, although the waterproof layer in the invention could be provided by a micro-porous membrane of an appropriate porosity.

Where layers of woven or knitted fabric are used to create a laminate according to the invention and those layers are pre-shrunk before being bound to the waterproof, windproof and breathable membrane, the lack of shrinkage does not reduce the ability of the laminate to be stretched without resulting in the failure of the membrane, the permanent deformation of the laminate or the de-lamination of the laminate.

The present invention is described here as being comprised of three layers of materials exclusive of the binding adhesive layers but any number of layers of two or more may be joined together to create a laminate of alternating layers of waterproof, windproof and breathable membrane bound to fabric or membrane bound to membrane or fabric bound to fabric or any combination of bound pairings of these materials. Brief Description of the Drawings

The present invention will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 is a schematic perspective view of a three-ply laminate according to the invention;

Figure 2 is a cross-sectional view of a three-ply laminate according to the invention;

Figure 3 is a cross-section view of a three-ply laminate according to the invention under longitudinal stretching force;

Figure 4 is cross-sectional view of a three-ply laminate according to the invention at rest either after the application of sufficient longitudinal stretching force to cause the waterproof, windproof and breathable membrane portion of the laminate to permanently deform or after the shrinking of the woven or knitted layers after their having been bound to the waterproof, windproof and breathable membrane.

Description of the Preferred Embodiment

Figure 1 illustrates a three-ply laminate according to the present invention comprised of a layer of woven or knitted fabric 1 with a high degree of elasticity; two layers of adhesive 2 arranged through a suitable process known in the art, such as screen printing or spraying, in dots of an average diameter of approximately one millimetre spaced with centres equal distances of two millimetres apart in a matrix extending in a plane equal to or greater than the surface area of the woven or knitted fabric 1 ; a hydrophilic membrane 3 of approximately 20- 30 microns thickness arranged in a plane coextensive with the layers of adhesive 2; a second layer of woven or knitted fabric 4. Figure 2 shows a cross-section through a three-ply laminate according to the present invention where a woven or knitted fabric layer 4 is bound to a hydrophilic membrane 3 with a layer of adhesive 2 that is not continuously applied but rather applied to the membrane 3 through a suitable process known in the art, such as screen printing or spraying, in dots of an average diameter of approximately one millimetre spaced with centres equal distances of two millimetres apart in a plane forming a two-dimensional matrix. A second layer of woven or knitted fabric 1 is bound to the other side of the membrane 3 with a second layer of adhesive 2 applied to the membrane 3 through a suitable process known in the art, such as screen printing or spraying, in dots of an average diameter of approximately one millimetre spaced with centres equal distances of two millimetres apart in a plane forming a two-dimensional matrix. The layers of laminate comprised of the membrane 2 and the layers of woven or knitted fabric 1 and 4 are assembled together as in Figure 2. The binding action joining the membrane 3 to the layers of woven or knitted fabric 1 and 4 may be accomplished by the drying of the assembled laminate, either under pressure or not, where an otherwise liquid adhesive is used for the adhesive 2 or by the application of sufficient heat and pressure to the assembled laminate where a heat-activated adhesive is used for the adhesive 2 but not so high a heat as to melt or deform the membrane 3 or the layers of fabric 1 and 4.

Figure 3 shows a cross-section through a three-ply laminate according to the present invention where a longitudinal force is applied to stretch the laminate. The layers of woven or knitted fabric 1 and 4 are stretched along the longitudinal axis of the laminate as is the hydrophilic membrane 3. The layers of adhesive 2 are stretched by an amount equal to the amount the fabric layers 1 and 4 and the membrane 3 are stretched. The points of contact between the dot- matrix layers of adhesive 2 and fabric layers 1 and 4 and between the dot- matrix layers of adhesive 2 and the membrane 3 do not change with expansion due to the stretching of the layers making up the laminate. The expansion of the dot-matrix layers of adhesive 2 sufficient to maintain the contact points between the adhesive and the layers of fabric and membrane comes about through the increase in the distance 5 between the centres of the dots of adhesive in the matrices comprising the adhesive layers 2. When the stretching force is removed, the elastic properties of the laminate allow it to recover its original shape as in Figure 2. The expansion and recovery of a laminate according to the invention is approximately the same whether stretched longitudinally, laterally or in both directions at the same time.

Figure 4 shows a cross-section through a three-ply laminate according to the present invention where a longitudinal force is applied to stretch the laminate beyond the limit of the elastic recovery properties of the membrane 3. When the stretching force is removed, the laminate my return to its original external shape through the elastic recovery properties of the woven or knitted fabrics 1 and 4, though the membrane 3 may be permanently deformed, the deformation 6 occurs between the contact points between the membrane 3 and the woven or knitted fabric layers 1 and 4 and does not affect the bond between those layers. While the membrane 3 may not return to its original shape, this deformation does not cause a de- lamination or separation of the layers 1, 3 and 4 comprising the laminate nor does it cause a distortion in the overall shape of the laminate. The structural integrity and functionality of the membrane 3 is preserved.

In a particularly preferred embodiment, a laminate made according to the present invention may be used to make waterproof, windproof, breathable and stretchable clothing for wear by persons engaged in physical activity out of doors. During such activity, the waterproof and windproof qualities of clothing so made are most desirable. So also is the ability of the clothing to draw moisture away from the wearer's body. The invention combines these qualities with the ability to stretch through the full range of the movements of the wearer's body. The inclusion of a hydrophilic membrane 3 would make clothing made of a laminate according to the invention waterproof, windproof and breathable through the action of the membrane 3 in permitting moisture to pass away from the wearer's body through osmosis when water vapour on the side of the membrane 3 closest to the wearer's body is at a higher relative pressure than atmospheric pressure. Clothing made of a laminate made according to the invention would be stretchable due to the elasticity inherent in the materials used to make up the laminate and to the dot-matrix arrangement of adhesive 2 binding the layers of the laminate together and preventing it from de-laminating when stretched. Where clothing made of a laminate made according to the invention is constructed to be close fitting to the wearer's body, the stretching of the laminate over the moving portions of a wearer's body increases the surface area of the membrane 3 in the laminate, as shown in Figure 4, at those areas. This increase in surface area increases the breathability of the laminate at those areas where moisture from the wearer sweating is most likely to be present.

While the preferred embodiment of the present invention contemplates the application of dots of adhesive with an average diameter of one millimetre being arranged in a matrix and spaced with centres two millimetres apart on both sides of a hydrophilic membrane, the average diameter of the dots of adhesive in an embodiment of the invention may be larger or smaller than one millimetre and need not all be of the same size. Also, the arrangement of the dots of adhesive in the invention is not limited to equal spacing of two millimetres apart and the spacing of the dots of adhesive may be greater or less than two millimetres apart and need not be uniform provided that the preponderance of the dots of adhesive do not overlap other dots of adhesive. Furthermore, a micro-porous membrane may be used in a laminate formed according to the invention in place of or in addition to a hydrophilic membrane and the application of adhesive before the assembly of the laminate is not limited to applications of adhesive to the hydrophilic or micro-porous membrane but instead may be made to one or more of the layers of woven or knitted fabric to be used in the laminate.