Patent Application
20150376832
The present invention relates to artificial leathers and in particular artificial leathers having modified properties.
Artificial leather, also known as synthetic leather, has widely been used to replace natural leather. Artificial synthetic leathers mimic the texture and surface finishing of natural leather and have advantages over natural leather with lower cost of production, resistance to mold growth, ease of cleaning, maintenance and storage, enhanced durability and non-animal origin.
Natural and artificial leathers are commonly used to make various fashion items such as clothing, handbags, shoes and belts. These leathers are also used to make furniture (for example, sofas), car seats, cases for handheld electronic devices and book bindings and the like.
Natural and artificial leathers are a popular material from which winter clothing is made, due to their good heat retention and wind proof properties. In recent years, leather (both natural and artificial) is used in the design of some summer fashions.
The present invention aims to provide an artificial leather having a modified property.
In particular, the present invention provides an artificial leather with improved thermal conductivity. The artificial leather of the present invention is particularly suitable for use in applications in which a soft feeling artificial leather with improved heat transfer property are required. These applications may include the use of artificial leather in cases for portable electronic devices, and the use of artificial leather clothing for wearing all over the year, especially in the summer.
Broadly speaking, the present invention describes several broad forms. Embodiments of the present invention may include one or any combination of the different broad forms herein described.
In a first broad form there is provided an artificial leather comprising
a fibrous substrate layer; and/or
at least one coating layer comprises a resin selected from the group consisting of polyurethane resin (PU) and polyvinyl chloride (PVC) resin;
wherein at least one thermally conductive material is disposed in the fibrous substrate layer and/or the at least one coating layer for increasing the thermal conductivity of the artificial leather.
Advantageously the at least one thermally conductive material may be dispersed in the resin of the at least one coating layer. Preferably, the at least one thermally conductive material selected from the group consisting of metal additives, carbon-based materials, ceramic materials and phase-change materials. Optionally the ceramic material is selected from the group consisting of aluminium oxide, magnesium oxide, zinc oxide, aluminium nitride, boron nitride and silicon carbide. Preferably, the at least one thermally conductive material may constitute 1-21% by weight of the at least one coating layer.
Optionally, the fibrous substrate layer may include the at least one thermally conductive material therein.
Preferably, the thermally conductive material may be selected from the group consisting of conductive yarns, carbon based materials, surface cool-feeling materials, glass materials, ceramic materials and phase-change materials and is a a fibre, yarn or fabric thereof. Optionally, the conductive yarn is a stainless yarn or a silver-coated conductive yarn.
Advantageously, the fibrous substrate may be woven or non woven materials having a density so as to substantially reduce the amount of air trapped between the fibres of the substrate.
Optionally, the first thermally conductive material is included in the fibrous substrate layer and a second thermally conductive material is dispersed in the at least one coating layer.
In a second broad form there is provided an artificial leather comprising
a fibrous substrate layer;
at least a first coating layer and a second coating layer successively laminated upon the fibrous substrate layer, wherein the first and second coating layers comprise polyurethane resin (PU) or polyvinyl chloride (PVC) resin; and
at least one thermally conductive material for increasing the thermal conductivity of the artificial leather wherein said thermally conductive material is disposed in at least one of the fibrous substrate layer, the first coating layer and the second coating layer.
Optionally the at least one thermally conductive material may be dispersed in the first coating layer and/or the second coating layer.
Advantageously a first thermally conductive material may be dispersed in the first coating layer and a second thermally conductive material may be dispersed in the second coating layer and wherein the first and second thermally conductive materials are independently selected from the group consisting of metal additives, carbon-based materials, ceramic materials and phase-change materials.
Preferably the ceramic material is selected from the group consisting of aluminium oxide, magnesium oxide, zinc oxide, aluminium nitride, boron nitride and silicon carbide.
Optionally, the fibrous substrate layer comprises a third thermally conductive material. Preferably the third thermally conductive material is selected from the group consisting of conductive materials, carbon based materials, surface cool-feeling materials, glass materials, ceramic materials and phase-change materials and wherein the conductive a fibre, yarn or fabric thereof.
Optionally, the conductive material is a stainless yarn or a silver-coated conductive yarn.
Advantageously, the fibrous substrate is woven or knit or non-woven substrate having a density so as to substantially reduce the amount of air trapped between the fibres of the substrate.
In a further broad form of the invention there is provided a product produced with the artificial leather herein described.
The product may be selected from the group consisting of garments, textiles, clothing, shoes, bags, belts, accessories, furniture, stationery, and cases/covers for an electronic device or other applications in which a soft feeling artificial leather with improved heat transfer properties may be useful.
In still another broad form there is provided a method of manufacturing an artificial leather comprising:
applying at least one coating layer comprising a resin selected from the group consisting of polyurethane resin (PU) and polyvinyl chloride (PVC) resin to a fibrous substrate layer wherein at least one thermally conductive material is included in the at least one coating layer and/or the fibrous substrate layer.
Preferably, the thermally conductive material may be dispersed in the at least one coating layer and the thermally conductive material may be selected from the group consisting of metal additives, carbon-based materials, ceramic materials and phase-change materials. Preferably the ceramic material is selected from the group consisting of aluminium oxide, magnesium oxide, zinc oxide, aluminium nitride, boron nitride and silicon carbide.
Optionally, the fibrous substrate layer includes the at least one thermally conductive material therein. Preferably, the thermally conductive material may be selected from the group consisting of conductive materials, carbon based materials, surface cool-feeling materials, glass materials, ceramic materials and phase-change materials and wherein the conductive material is a fibre, yarn or fabric thereof.
Preferably the conductive material may be a metal filament or a silver-coated conductive yarn.
The present invention is described by the following detailed description of preferred but non-limiting embodiments of the present invention by way of examples and with reference to the accompanying drawings, in which:—
a is a perspective view of an artificial leather according to an embodiment of the present invention;
b is the cross-sectional view of the artificial leather of
a is a perspective view of an artificial leather according to another embodiment of the present invention;
b is the cross-sectional view of the artificial leather of
a is a perspective view of an artificial leather according to yet another embodiment of the present invention;
b is the cross-sectional view of the artificial leather of
a shows the increase in thermal conductivity for an artificial leather including a substrate layer with cool-feeling nylon yarns or silver-coated conductive yarns, as compared with conventional cotton yarns.
b demonstrates the increase in thermal conductivity of substrate layer with density of the yarn forming the substrate layer;
c shows the thermal conductivities of various substrate layers formed from polyester yarn and silver coated conductive yarn;
a, 9b and 9c show the thermal conductivities of various polyurethane resin layers containing different weight percentages of Al2O3;
a and 10b show the thermal conductivities of various polyurethane resin layers containing different weight percentages of AlN;
a and 11b show the thermal conductivities of various polyurethane resin layers containing different weight percentages of SiC1500 (
a and 12b show the thermal conductivities of various two-layer artificial leathers containing different weight percentages of Al2O3 (
c and 12d show the thermal conductivities of two layer artificial leathers having a 30% Al203 content, different substrate layers and presence/absence of standard industrial additives.
a and 16b are respectively infrared images of convention polyurethane fabric and an the three-layer artificial leather of
The present invention provides an artificial leather having a increased heat transfer capacity advantageous for a wide range of industry applications, which can include textile products and accessories for electronic goods, such as cases for smart phones, in which overheating of electronics are undesirable and may cause damage to the phones.
In a broad form of the present invention, an artificial leather has disposed therein at least one thermally conductive material for increasing the thermal conductivity of the artificial leather. It can be understood by those skilled in the art that any thermal conductive material suitable in artificial leather production can be adopted for use in the present application, and such material can be readily tested and selected by a person skilled in the art.
Artificial leather of the invention includes a fibrous substrate layer; and/or at least one coating layer comprises a resin selected from the group consisting of polyurethane resin (PU) and polyvinyl chloride (PVC) resin.
The fibrous substrate layer, also known as the backing layer (generally comprises a woven, knitted or non-woven textile), and coating (resin) layer are commonly known to a person skilled in the art for preparation of artificial leather. The arrangement/configuration of the leather made from one or more of these layers would be readily appreciated by a person skilled in the art.
For example, the coating layer may be applied directly on to the fibrous substrate layer such that two layers may be provided adjacent to each other, or additional layers could be provided in between the two layers depending upon the desired properties of the final product. It is envisaged that additional functional layers, for example protecting layer and other layers for improving visual effect of the final product could be optionally included by those skilled in the art.
In an embodiment of the present invention, the artificial leather provided includes a fibrous substrate layer and a first and second coating layers comprising either polyurethane resin (PU) or polyvinyl chloride (PVC) resin, and optionally the leather includes additional functional layers as described above.
As would be appreciated by those skilled in the art, either one, two, or more of the fibrous substrate layer and the coating layer(s), if present, can be modified to include the desired thermally conductive material, by chemical processes known to a person skilled in the art.
According to a preferred embodiment of the present invention, the at least one thermally conductive material, such as metal additives, carbon-based materials, ceramic materials and phase-change materials, may be dispersed in the resin of the at least one coating (resin) layer as known to a person skilled in the art. In an exemplary embodiment, ceramic materials including aluminium oxide, magnesium oxide, zinc oxide, aluminium nitride, boron nitride, silicon carbide and the like can be adopted to improve the thermal conductivity of the coating (resin) layer.
Preferably, the thermally conductive material incorporated into the coating (resin) layer constitute 1-90%, 1-80%, 1-70%, 1-60%. 1-50%, 1-40% or 1-30% by weight of the coating layer. More preferably, the thermally conductive material incorporated into the coating (resin) layer constitute 1-25%, 1-20%, 1-15%, 1-10% or 1-5% by weight of the coating layer. In specific exemplary embodiments, the thermally conductive material incorporated into the coating (resin) layer constitutes 1-30%, 1-21%, 3-21%, 3-15%, 3-9% by weight of the coating layer.
According to a preferred embodiment of the present invention, the at least one thermally conductive material may be included in the fibrous substrate layer. The fibrous substrate layer may comprises one or more fibrous materials, including materials made with naturally occurring fibers (such as cotton, wool, silk,) semi-synthetic fibers and synthetic fibers (such as nylon, midacrylic, olefin, acrylic, polyester, carbon fiber, and the like).
The thermally conductive material, such as, conductive materials, carbon based materials, surface cool-feeling materials, glass materials, ceramic materials and phase-change materials, presented either as a fibre, yarn or fabric, can be incorporated into the fibrous substrate layer by fabrication method, such as weaving, knitting and any other method known to a person skilled in the art, by using by way of example, a high speed Jacquard machine.
In a further embodiment, the fibrous substrate may be further modified by removing air (so called “still air”) contained in the internal space of the fibrous substrate. This can be achieved by fabricating the layer in high density and/or adopting fabric structures which are more compact (e.g. plain structure is more compact compared to twill and satin although the fabrics are at the same density). The above modification can further improve the performance of the fibrous substrate, hence improving the thermal conductivity of the artificial leather.
It is envisaged that other agents, such as coupling agent, stabilizer, colouring agent e.g. a dye, and other additives for improving softness of leather can be added to the artificial leather.
The desired agents and the amount thereof can be readily ascertained by a person skilled in the art, for example, based upon the desired softness of the final product and its application (for clothing or electronic device). As would be appreciated by a person skilled in the art, coupling agent can be added to improve interfacial bonding between the composite and thermally conductive materials to ensure even dispersion of the thermally conductive materials (usually in form of particles).
The artificial leather of the present invention can be prepared by commonly known method, e.g. wet and dry process known to a person skilled in the art. The preparation of the leather differs from conventionally known method in that at least one thermally conductive material is included in the at least one coating layer and/or the fibrous substrate layer. Although specific method steps are disclosed in herein, it would be understood by a person skilled in the art that the additional of the thermally conductive material can be achieved by any commonly known method.
The artificial leather of the present invention can be used to manufacture garments, textiles, clothing, shoes, bags, belts, accessories, furniture and cases for an electronic device, merging technical innovation with socio-cultural trends. In particular, in light of the popularity of the use of cover cases for smart phones and tablets, it is envisaged that the artificial leather of the present invention can be used to prepare a high quality leather-looking cover case, which would allow effective dissipation of heat generated by such devices.
The artificial leather of the present invention provides an innovative and clever way of broadening the potential field of application for textile manufacturers. The artificial leather of the present invention also provides a way for smoothing the periodicity of demand which characterises leather/artificial leather goods (i.e. winter demand substantially outstrips that of summer).
As is shown in the art, a typical artificial leather structure is shown in a schematic view in
Preferred embodiments of the present invention will now be described with reference to
Structures of Artificial Leathers
a and 2b show an artificial leather comprising a resin coating comprising a resin coating layer 12 and a fibrous substrate layer 10 similar to the arrangement of
a and 3b show another artificial leather similarly comprising a resin coating layer 12 (which may be a polyurethane or a polyvinyl chloride resin layer) and a fibrous substrate layer 10. The fibrous substrate layer further comprises a thermally conductive material 15 that increases the thermal conductivity of the artificial leather.
a and 4b show a further artificial leather in which the resin layer 12 includes a thermally conductive material 14 disposed throughout the resin, together with a thermally conductive material 15 which has been included in the fibrous substrate layer 10.
In another embodiment of the present invention, as depicted in
Manufacture of Fibrous Substrate Layer, Coating Layer and Artificial Leather
Typical steps in the production of artificial leather are detailed below, together with modifications according to the present invention.
1. Manufacture of Fibrous Substrate Layer
As is known to persons skilled in the art, the fibrous substrate layer 10 may be woven, knitted or non-woven in plain, twill or satin weaving or other similar arrangements. These structures can be produced from a textile material, for example fiber, yarn and fabric by a skilled person through conventional means. The density of the textile material in the fibrous substrate layer may also be varied with known methods.
The exemplary artificial leathers depicted in
2. Manufacture of Artificial Leather
Optionally, the leather may be manufactured by either wet or dry processing or a combination of both modes as detailed below.
Referring to
The substrate layer and the PU paste were immersed in a DMF/H2O (v/v, 1/5) mixture for 15 min to cure the resin coating layer. The cured artificial leather was then dried, rolled, and rinsed repeatedly to remove any DMF.
Alternatively, artificial leather may be produced by dry processing as shown in
Referring now to
The dried resin coating layer 12 can then be peeled off from the backing paper and laminated to a fibrous substrate layer to produce an artificial leather. Alternatively, an additional thin layer of PU/DMF paste can be spread onto the resin layer, and a laminated fibrous substrate laminated thereto, adhering to the resin layer. Subsequently, after oven drying, the resin/fibrous substrate may be peeled off from the backing paper.
In still a further technique artificial leather with a three-layer structure such as that shown in
Measurement of Thermal Conductivity
Method
The thermal conductivities of the following fibrous substrate layers, resin coating layers and artificial leathers were measured by a KES-F7 Thermo Labo II instrument (KATO Tech Co. Ltd.) according to the instrument's manual.
Results
1. Effect of Fiber Material and Fabric Density on the Thermal Conductivities of Fibrous Substrate Layer
Fibrous substrate layers with a knitting structure were prepared with cotton yarn, surface cool-feeling nylon yarn and silver-coated conductive yarn. The thermal conductivity of the resultant fibrous substrate layer is reported in
In another experiment, fibrous substrate layers P25S1 and P30S1, both having plain weaving structures, were made from cotton yarn and silver-coated conductive yarn wherein the yarns were woven at different densities. The weaving structure of the P25S1 and P30S1 layers are shown in Table 1 below.
The thermal conductivities of P25S1 and P30S1 are shown in
The effects of incorporation of thermally conductive yarn and variation on yarn density on the thermal conductivity of the fibrous substrate layer are further investigated with the substrate layers in Table 2.
As seen from
2. Effect of Al2O3, AlN and SiC on the Thermal Conductivities of Resin Coating Layer
Polyurethane resin coating layers comprising various amounts of aluminium oxide (Al2O3) were prepared.
The thermal conductivities of the resultant coating layers are report in
3. Thermal Conductivities of Various Two-Layer Artificial Leathers
Artificial leathers were producing with resin coating layers comprising different concentrations of AL2O3 or AlN and fibrous substrate layer selected from 30 P-S, 30 Silver and 60 Silver (see Table 2). The thermal conductivities of these artificial leathers were measured and the results are shown in
By dispersing either AL2O3 or AlN in the resin coating layer, the thermal conductivities of these artificial leathers is significantly improved. Further, it can be seen the best thermal conductivity is obtained with 60 Silver as the fibrous substrate layer. The expectation is that this is a result of the high density of silver-coated conductive yarn in the fibrous substrate.
Further experiments have also been conducted as shown below, in which the artificial leather was prepared using the wet method, at a 30% concentration.
The appearance, strength and texture of the artificial leathers are under comparison, including with the presence/absence of normal industry additives, such as Polyurethane, PS-80, PS-18, DMF, Al2O3, Shiming Black Pigment as shown below in Table 3.
The conductivity of the specimen made by the Wet method was then assessed, for the Polyester 30 and PS silver at 30% AL203 addition with and without exemplary additives.
4. Thermal Conductivity of a Three-Layer Artificial Leather
A three-layer artificial leather 18 as schematically illustrated in
The thermal conductivities of the three-layer artificial leather 18 and four commercially available polyurethane based artificial leathers were measured. The thermal conductivities of the four commercial samples are respectively 0.0585, 0.0505, 0.059 and 0.0635 w/mK. The average of these values (0.058 w/mK) was compared to the thermal conductivity of the three-layer artificial leather (0.086 w/mK) in
The thermal conductivity of the three-layer artificial leather 18 was also investigated by infrared thermal imaging techniques. A heat source 100 as illustrated in
The images are shown in
In another thermal imaging experiment, a human body was used as the heat source. A vest comprising two halves, as shown in
As seen from
It can be appreciated that an artificial leather having improved thermal conductivity provides an increased range of options for clothing, electronic cases, car seats and the like, wherever artificial leather is used. (The artificial leather may include modified fabric substrate, or be formed from resin layers having thermally conducting material dispersed therein). The potential use of artificial leather with enhanced thermal conductivity potentially offers fashion designers and accessories manufacturers a potentially new material for inclusion in summer clothing, electronic cases and the like—widening the palette of materials available.
The artificial leather having improved functional properties of the present invention is a novel approach with a combination of traditional fabrication technologies with smart conductive fabrics. The improved artificial leather provides the opportunity for increasing the value chain of production in the local region, offering a differentiated, technologically advanced fabric suitable for use in a wide range of applications.
The improved thermal conductivity of the artificial leather of the present invention also reduces the periodicity in demand typically associated with artificial leather used in the textile industry. Artificial leather of the present invention has an increased suitability for a wider breadth of applications and an enhanced suitability and comfort of the material for a user in an environment having elevated temperatures in traditional applications. Artificial leather with improved thermal conductivity is a bold departure from traditional thinking as it provides significantly enhanced user comfort, particularly in the clothing arena.
While the present invention has been explained by reference to the examples or preferred embodiments described above, it will be appreciated that those are examples to assist understanding of the present invention and are not meant to be restrictive. Variations or modifications which are obvious or trivial to persons skilled in the art, as well as improvements made thereon, should be considered as equivalents of this invention.
Furthermore, while the present invention has been explained by reference to two embodiments, and specific configurations of the extraction system depicted therein, it should be appreciated that the invention can apply, whether with or without modification, to other arrangements without loss of generality.
