MXPA06006492A - Synthetic insulation with microporous membrane - Google Patents

Abstract

An insulation package and method of formation including a functional fabric layer, a breathable water repellant insulating layer, and a highly breathable microporous membrane layer having a network of pores. The functional fabric, the highly breathable insulating layer and the microporous membrane layer are laminated to one another to form a waterproof breathable insultion package.

Description

SYNTHETIC INSULATION WITH MICROPOROSE MEMBRANE Background of the Invention 1. Field of the Invention The present invention is directed to a waterproof breathable insulating material and in particular to such material for use in outdoor clothing and boots. 2. Description of Related Art Outdoor enthusiasts have continuously demanded technically advanced mechanisms to protect themselves from the elements. This demand has resulted in the development of various constructions of breathable water-repellent fabric, wherein the fabric is typically laminated to these thin films or membranes. Waterproof breathable fabrics have been used in functional garments for many decades and have proven to be a preferred performance component. Both the prevention of the water reaching the body from the outside of the clothes and the removal of steam produced by the body are of great importance for the one who uses it in terms of comfort. However, the downside of such fabrics has always been that although they are classified as being breathable, they do not offer significant transport of wet steam. In addition, most breathable fabrics tend to have very limited insulating properties. Still further, fabrics laminated to certain types of membrane types tend to be very flexible and generate noise when used. According to the above, despite the demands most breathable water repellent fabrics tend to be less breathable than desired, they offer limited insulating properties so that they must be used in conjunction with some form of insulating material and require the user support its rigidity and natural noise. Insulating materials are often used in conjunction with or incorporated into functional garments to provide thermal protection. However, most insulating materials do not provide water repellency or alternatively provide water repellency at the expense of a corresponding decrease in thermal protection. PrimaLoft® insulation, as described in the US Patents Nos. 4,992,327 and 4,588,635 and are incorporated herein by reference, is unique in the world of synthetic insulators in that it offers superior water repellency in addition to thermal performance indicative of micro and fine fiber construction. However, PrimaLoft® insulation has been used primarily as a replacement for natural down with the added benefit that it is waterproof. Alternatively, the PrimaLoft® fibrous material block has been incorporated into the manufacture of garments wherein this is a separate insulating layer. It is often mechanically secured to other layers of woven and nonwoven material for example through padding. However PrimaLoft® insulation by itself does not have. sufficient structural integrity or aesthetic appearance to be sufficient both as insulating material and outer layer for clothing. Another element of many waterproof breathable fabrics are monolithic membrane films that are used to impart a breathable barrier to the fabric. Monolithic membranes promote the permeation of water vapor through the use of a layer of hydrophobic polymer that absorbs water close to the skin and transmits it to the external environment. Unfortunately, monolithic films typically experience significant volume increase of the hydrophilic layer that significantly alters the film's vapor removal characteristics and comfort for the user. Furthermore, although this type of membrane also has a very high tear strength which is generally favorable for functional fabrics, this also results in extraordinary stiffness in a garment that is not usually seen as a positive attribute. According to the foregoing, there is a need for a waterproof breathable insulation material that provides superior water repellency or waterproof features coupled with superior characteristics for vapor removal that will not increase in volume and have sufficient tear strength, but not unduly rigid or noisy for the user. SUMMARY OF THE INVENTION One embodiment of the present invention is directed to an insulating package having a functional fabric layer, a highly breathable microporous membrane layer having a network of pores and a breathable water repellent insulating layer, the layers being laminated between yes to form a waterproof breathable insulated fabric. In another embodiment, of the present invention the insulating layer is a breathable water-repellent insulating layer in the form of a cohesive fiber structure, the structure of which comprises a splice of: (a) from 70 to 95% percent by weight of rrticrofibres synthetic polymers that have a diameter of from 3 to 12 microns; and (b) from 5 to 30 percent by weight of synthetic polymeric macrofibers having a diameter of from 12 to 50 microns. The present invention is also directed to a method for forming an impermeable insulating package. The steps include providing a first layer of the functional fabric, a second microporous membrane layer and a third breathable water repellent insulating layer. In addition, the first layer is attached to the second layer and the second layer to the third. The various features of novelty characterizing the invention are pointed out in particular in the appended claims and which form a part of this invention.

For a better understanding of the invention, its operational advantages and specific objectives achieved through its uses, reference is made to the accompanying descriptive matter in which they are illustrated in the preferred embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the invention, reference is made to the following description and accompanying drawings, in which: Figure 1 is a cross-sectional view of an impermeable insulating package according to the present invention; and Figure 2 is a cross-sectional view of an impermeable breathable insulating package according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings, the present invention is directed towards an insulating package 10 shown in general in Figure 1 which is both waterproof and breathable. As shown in Figure 1, an insulating package 10 is comprised of an insulating material 12, a microporous membrane 14 and a functional fabric 16. The insulating material 12, the microporous membrane 14 and the functional fabric 16 are bonded together, preferably through known lamination techniques. In a preferred embodiment, the laminated package 10 consists of PrimaLoft® insulation as the insulating material 12 and any woven or non-woven wool or other fabric structure such as the functional fabric 16 adhered or laminated to the surface of the microporous membrane 14, which is laminates itself to PrimaLoft® insulation. In certain situations it may be desirable to add an additional layer of functional fabric or a coating 18 on the non-membrane side of the insulating material 12 as shown in Figure 2. A microporous membrane 14 is preferred because it has a highly breathable interconnected network of micropores that can be manipulated. The breathing and permeability properties of the microporous membrane 14 are selectively defined through stretching and manipulation of the membrane. This stretching alters the original pore size of the membrane. In addition, the microporous membrane lends itself to applications that use lamination techniques. In the application of a network of pores the microporous membrane is constructed in such a way that the operating trajectory and the pore size allow the optimal transfer of the wet vapor while still inhibiting the transfer of water, not yet to the acceptable level for considered as a waterproof breathable membrane. One of the advantages of the microporous membrane 14 is that it does not absorb water or exhibit an increase in volume. The monolithic membranes of the prior art are typically based on polyurethane and function through the solubility of the water molecules in the membrane layer. As a result, despite their general resistance to tearing, they are less desirable since they are prone to volume increase. Such an increase in volume is known to alter the hydrophilic properties of the monolithic membranes. In contrast, microporous membranes function through the diffusion of moist vapor through the pores. The typical pore size 'is for example between 1 and 8 μm. Due to this pore size range, the microporous membrane of the present invention is not considered waterproof or hydrophobic by itself. In addition, microporous membranes are typically formed of polytetrafluoroethylene or other polymeric material with low crystallinity (generally less than 30%). In addition, the polymeric material can be mixed with an inorganic filler with a particle size of 0.5-5 μm. A microporous membrane can generally have a thickness of approximately between 30 and 50 μm. Importantly, such microporous membranes do not experience the common volume increase of the monolithic membranes. In addition, by laminating the insulating layer 12 to a microporous membrane 14 the tear resistance of the microporous membrane, which is generally less than that of the monolithic membranes., it increases greatly. In addition, the rigidity of the combination is significantly less than that created by joining an insulating material to a monolithic membrane. To further improve the waterproof nature of the insulating package, the functional layer 16 can be covered with a durable water repellent treatment or waxing coating. According to one aspect of the present invention, the insulating layer 12 is a synthetic fiber thermal insulating material, in the form of a cohesive fiber structure, the structure of which comprises a splice of: (a) from 70 to 95 percent by weight Weight of synthetic polymeric microfibers having a diameter from 3 to 12 microns; and (b) from 5 to 30 percent by weight of synthetic polymeric macrofibers having a diameter of from 12 to 50 microns, wherein at least some of the fibers are joined at their contact points, the bond being such that the density of the resulting structure is within the range of 3 to 16 kg / m3 (0.2 to 1.0 Ib / ft3), the bonding being carried out without significant loss of the thermal insulating properties of the structure compared with the unattached splice. The microfibers and macrofibers for use in the present invention may be made of polyester, nylon, rayon, acetate, acrylic, modacrylic, polyolefins, elastomeric fiber, polyaramides, polyimides, fluorocarbons, polybenzimidazoles, polyvinylalcohols, polydiacetylenes, polyetherketones, polyimidazoles and sulfide polymers. phenylene such as those commercially available under the trade name RYTON or any other material suitable for the purpose. The bonding can be made between at least some of the macrofibers to form a support structure for the microfibers or it can be both between macrofibers and microfibers at various points of contact. The macrofibres can be selected from the same material or from a variety of materials and can either be the same material as the microfibers or different. In an advantageous embodiment of the invention the microfibers are formed from polyethylene terephthalate and the macrofibres are selected from polyethylene terephthalate or a polyaramide such as, for example, that commercially available under the trademark "Kevlar". The macrofibers can be monofibers, i.e., fibers having a substantially uniform structure, or they can be multi-component fibers having a residue to facilitate the fiber binding to the fiber. The fiber may be a blend of fibers in which at least 10% by weight comprises macrofibers of a low melting point thermoplastic material to assist the fiber in the bonding of fibers. In a further embodiment of the invention, the macrofibres can be a mixture of fibers comprising multi-component macrofibres and a monocomponent macrofibre capable of joining together and / or with the microfibers. In another embodiment of the present invention the macro component fiber can be a set or mixture of macro fibers having different properties for example, a macro fiber blend can comprise two or more different fibers such as a polyester fiber to give the desired bond and a "Kevlar" fiber to give rigidity. The ratio of the stiffness fiber to join the fiber can be varied to provide different properties subject to the requirement that the ratio of unbondable fibers be sufficient for the structure of the macro fiber to provide an open support for the microfibers as described hereinafter. Some materials, such as, for example, polyphenylene sulfide fibers, aromatic polyamides of the type commercially available under the tradename "APYIEL" and polyimide fibers such as those manufactured by Lenzing AG of Austria, exhibit fire retardant or non-flammable properties. . Such materials can therefore confer improved flame or fire resistant properties in the fabricated products containing the materials according to the present invention. The joining of the fibers of the insulating layer 12, according to one aspect of the invention, is preferably mainly between the fibers of the macro fiber component at their contact points. The purpose of the macro fiber to join the macro fiber is to form a support structure for the micro fiber component, this support structure significantly contributing to the mechanical properties of the insulating material. By joining the macrofibers, the macrofibers maintain an open, bonded fiber structure within which microfibers can be accommodated. Alternatively, the macrofibers and / or the microfibers can be joined at their points of contact. Any means of bonding between the macro fibers may be employed such as, for example, by the addition of solid, gaseous or liquid bonding agents or preferably through the application of heat to cause the lower temperature fiber component to melt and melt at the points of contact. The method of joining the components of the insulating layer 12 is not critical, subject only to the requirement that the joint must be carried out under such conditions that neither the fiber component loses its structural integrity. It should be appreciated by one skilled in the art that any appreciable change in the macro- or micro-fibers during bonding will adversely affect the thermal properties; the joining step therefore needs to be conducted to maintain the physical properties and dimensions of the fiber components and the splice as much as possible. The thermal insulating properties of the bonded insulating layer 12 are substantially preferably the same or not significantly less than the thermal insulating properties of a similar non-bonded joint. In a particular embodiment of the present invention the joint within the insulating layer 12 can be affected by heating the fibers for a time and at a temperature sufficient to cause the fibers to join. Such a heating period can be at a temperature of from about 125 ° C (257 ° F) to 225 ° C (437 ° F) for a period of the order of 1 minute to 10 minutes and preferably at a temperature of about 140 °. C (284 ° F) at 200 ° C (392 ° F) for a period of about 3 to 7 minutes; these periods, of course, depend on the materials of the mixture of fiber components. PrimaLoft® as described above is suitable for lamination applications with a microporous membrane as described herein. Lamination techniques require a substantially smooth surface on the insulation for the application and substantially adhesion to a fabric. This smooth surface can be created through a process known in the art such as IR calendering, calendering with a hot plate, heated rolls, resin coatings and / or single processing with a hot air oven (defined only as temperature and flow handling). air). In addition to the surface treatments, the internal structure of the block of fibrous material needs to be well joined in order to maintain the integrity of the structure through the repeated use and washing of a laminated article without delaminating. Although a Primaloft® insulation and in particular a fibrous material block material formed from Primaloft® is used in the preferred embodiment, it is to be understood that other insulating materials may be used without departing from the scope of the present invention including woven and non-woven insulating materials formed of natural and synthetic fibers or mixtures thereof. Experimental Data This insulating package 10 provides protection against water up to 2.0 psi of hydrostatic pressure in accordance with the AATCC Test Method 127 entitled "Water Resistance: Hydrostatic Pressure Test" (Water Resistance: Hydrostatic Pressure Test). It is typically accepted in the outerwear industry that any fabric with a hydrostatic pressure capacity above 2.0 psi is considered impervious by definition. AATCC is the abbreviation of the American Association of Textile Chemists and Colorists (American Association of Textile Chemists and Colorists). AATCC 127 is a test method that measures the resistance of a fabric to the penetration of water under hydrostatic pressure and is applicable to all types of fabrics. A surface of the test sample is subjected to pressurized water where the pressure is increased at a constant rate until three filtration points are observed on the other side of the sample. In one experiment, the insulating package 10 using a block of Primaloft® fibrous material as the insulating layer 12 was found to have a hydrostatic pressure resistance exceeding 185 crn-t ^ 0 or 2.63 psi. According to the above, the insulating package 10 was found to exhibit water resistance characteristics that far exceed that need to be considered waterproof. Another test carried out on the insulating package was the determination of the Water Vapor Transmission Rate (WVTR). This was done in accordance with ASTME 96-00 Procedure E. The WVTR is a test to determine the amount of water vapor that can pass through the fabric during a given period. For example, a known microporous membrane frequently cited in the prior art as a basis of comparison and control in experiments is CELGARD® 2500 known to have a WVTR of 5000 g / m2 / 24 hours. The breathable outerwear of the prior art such as that described in Example 1 of the US Patent. No 6, 100,208 have a first multi-component fiber layer, a second multi-component fiber layer and a water-impermeable barrier therebetween formed of low density polyethylene which has been shown to have a WVTR of 3465 g / m2 / 24 hours. However, the garment described in the '208 patent does not provide an insulating layer such as that of the present invention. It should be expected that the addition of an insulating layer could decrease the WVTR of the outdoor fabric. The test of the insulating package of the present invention was carried out at 37.8 ° C and at 90% relative humidity. In this test a sample of laminated SUPPLEX fabric, microporous membrane material and Primaloft® insulation, as described in the present invention achieves a WVTR of 3521 g / m2 / 24 hours. This is significant because the test sample provides an insulating layer not present in the two examples described above, it still has higher WVTR than the non-insulated laminated outer fabric and a WVTR almost as large as that of the microporous membrane itself . As such, the insulating package of the present invention demonstrates that the wearer of clothing constructed using the insulating package should expect to remain in reasonable comfort despite significant athletic activity. It has thus been demonstrated that the objectives set forth above, among those made apparent from the preceding description, are efficiently achieved and because certain changes can be made by carrying out the above method and in the construction (s) ) established without departing from the spirit and scope of the invention, it is intended that all the material contained in the above description and shown in the accompanying drawings be construed as illustrative and not in a limiting sense.

Claims (20)

1. CLAIMS 1. An insulating package comprising: at least one functional fabric layer; a highly breathable microporous membrane layer that has a network of pores, an insulating layer that repels respirable water; and wherein the functional fabric, the microporous membrane layer and the insulating layer are laminated together to form a waterproof breathable insulated fabric. The insulating package of claim 1, wherein at least one of the at least one of the functional fabric layers is a water resistant fabric. 3. The insulating package of claim 2, wherein the functional fabric layer is covered with a wax coating. 4. The insulating package of claim 1, further comprising a second functional fabric layer. The insulating package of claim 4, wherein the second functional fabric is laminated to the insulating layer on the non-membrane side. 6. The insulating package of claim 1, wherein the size of a pore in the pore network is defined by stretching, the microporous membrane. 7. The insulating package of claim 1, wherein said insulating package allows steam to be transferred and inhibits water transfer. The insulating package of claim 1, wherein the highly breathable water-repellent insulation is nonwoven and comprises fibers selected from the group consisting of microfibers, macro fibers, natural fibers and mixtures thereof. The insulating package of claim 1, wherein the highly breathable water-repellent insulation is woven and comprises fibers selected from the group consisting of microfibers, macro fibers, natural fibers and mixtures thereof. The insulating package of claim 1, wherein the highly breathable water-repellent insulating layer has a cohesive fiber structure comprising a splice of: (a) from 70 to 95 percent by weight of spun synthetic polymer microfibers and stretched, having a diameter from 3 to 12 microns; and (b) from 5 to 30 percent by weight of synthetic polymer macrofibres having a diameter of 12 to 50 microns. The insulating package of claim 1, wherein the breathable water resistant insulating layer formed as a block of fibrous material has a smooth surface compatible for lamination techniques. 12. The insulating package of claim 11, wherein the smooth surface is formed by at least one process selected from the group consisting of IR calendering, calendering with hot iron, using hot rollers, resin coatings and / or furnace processing. hot air. 13. The insulating package of claim 1, wherein the functional fabric is selected from the group consisting of woven and nonwoven wool fabrics. 14. A method for forming an impermeable insulating package comprising the steps of: providing a first functional fabric layer; provide a second microporous membrane layer; provide a third layer of water repellent, breathable insulation; joining the first layer to said second layer; and join the second layer to the third layer. 15. The method of claim 14, further comprising the step of forming the third layer as a block of fibrous material. 16. The method of claim 15, further comprising the step of forming a smooth surface on said block of fibrous material. 17. The method of claim 14, wherein the joining of the first and second layers is a lamination process. 18. The method of claim 14, wherein the joining of the second and third layers is a lamination process. 19. The method of claim 14, further comprising the step of providing a second layer of functional fabric. The method of claim 17, wherein the second functional fabric layer is laminated to the insulating layer.