U.S. patent application number 14/320318 was filed with the patent office on 2015-12-31 for artificial leather.
The applicant listed for this patent is The Hong Kong Polytechnic University. Invention is credited to Li Li, Jingping Wang, Chenxiao Yang.
Application Number | 20150376832 14/320318 |
Document ID | / |
Family ID | 54929904 |
Filed Date | 2015-12-31 |
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United States Patent
Application |
20150376832 |
Kind Code |
A1 |
Li; Li ; et al. |
December 31, 2015 |
ARTIFICIAL LEATHER
Abstract
An artificial leather comprising a fibrous substrate layer;
and/or at least one coating layer. The coating layer comprises a
resin selected from the group consisting of polyurethane resin (PU)
and polyvinyl chloride (PVC) resin. The artificial leather also
includes at least one thermally conductive material is disposed in
the fibrous substrate layer and/or the at least one coating layer
for increasing thermal conductivity.
Inventors: |
Li; Li; (Hong Kong, HK)
; Yang; Chenxiao; (Hong Kong, HK) ; Wang;
Jingping; (Hong Kong, HK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Hong Kong Polytechnic University |
Hong Kong |
|
HK |
|
|
Family ID: |
54929904 |
Appl. No.: |
14/320318 |
Filed: |
June 30, 2014 |
Current U.S.
Class: |
428/423.3 ;
428/423.1; 428/426; 428/446; 428/457; 442/59 |
Current CPC
Class: |
D06N 3/0002 20130101;
D06N 3/0009 20130101; D06N 3/0011 20130101; D06N 3/145 20130101;
D06N 3/06 20130101; D06N 2209/062 20130101; D06N 3/0063 20130101;
D06N 3/14 20130101 |
International
Class: |
D06N 3/14 20060101
D06N003/14; D06N 3/00 20060101 D06N003/00 |
Claims
1. 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.
2. The artificial leather of claim 1, wherein the at least one
thermally conductive material is dispersed in the resin of the at
least one coating layer.
3. The artificial leather of claim 2, wherein the at least one
thermally conductive material selected from the group consisting of
metal additives, carbon-based materials, ceramic materials and
phase-change materials.
4. The artificial leather of claim 3, wherein the ceramic material
is selected from the group consisting of aluminium oxide, magnesium
oxide, zinc oxide, aluminium nitride, boron nitride and silicon
carbide.
5. The artificial leather of claim 2, wherein the at least one
thermally conductive material constitutes 1-30% by weight of the at
least one coating layer.
6. The artificial leather of claim 1, wherein the fibrous substrate
layer includes the at least one thermally conductive material
therein.
7. The artificial leather of claim 6, wherein the 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 is a fibre, yarn or fabric thereof.
8. The artificial leather of claim 7, wherein the conductive yarn
is a metal filament or a silver-coated conductive yarn.
9. The artificial leather of claim 1, wherein the fibrous substrate
is formed as a woven knit or non-woven fabric having a density so
as to substantially reduce the amount of air trapped between the
fibres of the substrate.
10. The artificial leather of claim 1, wherein a 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.
11. 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.
12. The artificial leather of claim 11, wherein the at least one
thermally conductive material is dispersed in the first coating
layer and/or the second coating layer.
13. The artificial leather of claim 11, wherein a first thermally
conductive material is dispersed in the first coating layer and a
second thermally conductive material is 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.
14. The artificial leather of claim 13, wherein the ceramic
material is selected from the group consisting of aluminium oxide,
magnesium oxide, zinc oxide, aluminium nitride, boron nitride and
silicon carbide.
15. The artificial leather of claim 11, wherein the fibrous
substrate layer comprises a third thermally conductive
material.
16. The artificial leather of claim 15, wherein 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 is a fibre, yarn or fabric thereof.
17. The artificial leather of claim 16, wherein the conductive yarn
is a metal filament, or a silver-coated conductive yarn.
18. The artificial leather of claim 11 wherein the fibrous
substrate is formed as a woven knit or non-woven fabric having a
density so as to substantially reduce the amount of air trapped
between the fibres of the substrate.
19. A product produced with the artificial leather of claim 1.
20. A product produced with the artificial leather of claim 1
wherein the product is selected from the group consisting of,
textiles, clothing, shoes, bags, belts, accessories, furniture and
cases for an electronic device.
21. 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.
22. The method of claim 21, wherein the thermally conductive
material is dispersed in the at least one coating layer and the
thermally conductive material is selected from the group consisting
of metal additives, carbon-based materials, ceramic materials and
phase-change materials.
23. The method of claim 22, wherein the ceramic material is
selected from the group consisting of aluminium oxide, magnesium
oxide, zinc oxide, aluminium nitride, boron nitride and silicon
carbide.
24. The method of claim 21, wherein the fibrous substrate layer
includes the at least one thermally conductive material
therein.
25. The method of claim 24, wherein the thermally conductive
material is 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
fibre, yarn or fabric thereof.
26. The method of claim 25, wherein the conductive yarn is a
stainless yarn or a silver-coated conductive yarn.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to artificial leathers and in
particular artificial leathers having modified properties.
BACKGROUND OF THE INVENTION
[0002] 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.
[0003] 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.
[0004] 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.
SUMMARY OF THE INVENTION
[0005] The present invention aims to provide an artificial leather
having a modified property.
[0006] 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.
[0007] 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.
[0008] In a first broad form there is provided an artificial
leather comprising
[0009] a fibrous substrate layer; and/or
[0010] at least one coating layer comprises a resin selected from
the group consisting of polyurethane resin (PU) and polyvinyl
chloride (PVC) resin;
[0011] 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.
[0012] 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.
[0013] Optionally, the fibrous substrate layer may include the at
least one thermally conductive material therein.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] In a second broad form there is provided an artificial
leather comprising
[0018] a fibrous substrate layer;
[0019] 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
[0020] 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.
[0021] Optionally the at least one thermally conductive material
may be dispersed in the first coating layer and/or the second
coating layer.
[0022] 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.
[0023] Preferably the ceramic material is selected from the group
consisting of aluminium oxide, magnesium oxide, zinc oxide,
aluminium nitride, boron nitride and silicon carbide.
[0024] 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.
[0025] Optionally, the conductive material is a stainless yarn or a
silver-coated conductive yarn.
[0026] 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.
[0027] In a further broad form of the invention there is provided a
product produced with the artificial leather herein described.
[0028] 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.
[0029] In still another broad form there is provided a method of
manufacturing an artificial leather comprising:
[0030] 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.
[0031] 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.
[0032] 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.
[0033] Preferably the conductive material may be a metal filament
or a silver-coated conductive yarn.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] 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:--
[0035] FIG. 1 depicts the structure of typical artificial
leather;
[0036] FIG. 2a is a perspective view of an artificial leather
according to an embodiment of the present invention;
[0037] FIG. 2b is the cross-sectional view of the artificial
leather of FIG. 2a;
[0038] FIG. 3a is a perspective view of an artificial leather
according to another embodiment of the present invention;
[0039] FIG. 3b is the cross-sectional view of the artificial
leather of FIG. 3a;
[0040] FIG. 4a is a perspective view of an artificial leather
according to yet another embodiment of the present invention;
[0041] FIG. 4b is the cross-sectional view of the artificial
leather of FIG. 4a;
[0042] FIG. 5 is a perspective view of a three-layer artificial
leather according to a further embodiment of the present
invention;
[0043] FIG. 6 is a schematic diagram illustrating the steps for
preparing artificial leather by wet processing;
[0044] FIG. 7 is a schematic diagram illustrating the steps for
preparing artificial leather by dry processing;
[0045] FIG. 8a 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.
[0046] FIG. 8b demonstrates the increase in thermal conductivity of
substrate layer with density of the yarn forming the substrate
layer;
[0047] FIG. 8c shows the thermal conductivities of various
substrate layers formed from polyester yarn and silver coated
conductive yarn;
[0048] FIGS. 9a, 9b and 9c show the thermal conductivities of
various polyurethane resin layers containing different weight
percentages of Al.sub.2O.sub.3;
[0049] FIGS. 10a and 10b show the thermal conductivities of various
polyurethane resin layers containing different weight percentages
of AlN;
[0050] FIGS. 11a and 11b show the thermal conductivities of various
polyurethane resin layers containing different weight percentages
of SiC1500 (FIG. 11a) and SiC2000 (FIG. 11b);
[0051] FIGS. 12a and 12b show the thermal conductivities of various
two-layer artificial leathers containing different weight
percentages of Al.sub.2O.sub.3 (FIG. 12a) or AlN (FIG. 12b) and
formed with substrate layers of various compositions and
densities;
[0052] FIGS. 12c 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.
[0053] FIG. 13 shows a three-layer artificial leather manufactured
according to an embodiment of the present invention;
[0054] FIG. 14 compares the thermal conductivities of commercially
available artificial leathers with the three-layer artificial
leather of FIG. 13;
[0055] FIG. 15 is a sketch of a heat source for applying heat to
artificial leather;
[0056] FIGS. 16a and 16b are respectively infrared images of
convention polyurethane fabric and an the three-layer artificial
leather of FIG. 13 after being heated for 10 seconds;
[0057] FIG. 17 is a vest comprising two halves, wherein one-half of
the vest was made with commercially available artificial leather
and the other half of the vest was made with the three-layer
artificial leather of FIG. 13;
[0058] FIG. 18 is an infrared image of the vest of FIG. 17 worn by
a human subject.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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.
[0067] 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.
[0068] 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).
[0069] 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.
[0070] 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.
[0071] 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.
[0072] 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).
[0073] 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.
[0074] 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.
[0075] 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).
[0076] As is shown in the art, a typical artificial leather
structure is shown in a schematic view in FIG. 1. A resin coating
layer 12 comprising polyurethane (PU) or polyvinyl chloride (PVC)
is attached to a fibrous substrate layer (or base layer 10). The
fibrous substrate layer 10 may be woven or non-woven and may
comprise polyester or cotton yarn.
[0077] Preferred embodiments of the present invention will now be
described with reference to FIGS. 2 to 17. Although the invention
is described herein with reference to specific embodiments of the
invention, it would be readily understood by a person skilled in
the art that alternative embodiments of the present invention may
be suitably configured for use in other applications.
[0078] Structures of Artificial Leathers
[0079] FIGS. 2a 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 FIG. 1. However,
as shown in the enlarged view a thermally conductive material 14
that increases the thermal conductivity of the artificial leather
is dispersed in the resin coating layer 12.
[0080] FIGS. 3a 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.
[0081] FIGS. 4a 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.
[0082] In another embodiment of the present invention, as depicted
in FIG. 5, a three layer artificial leather 16 comprises a fibrous
substrate layer (base layer) 10, a first coating layer and a second
coating layer (20 and 22). The first and second coating layers 20,
22 are successively laminated on the substrate layer 10. A
thermally conductive material which increases the thermal
conductivity of the artificial leather may be disposed in one, two
or each of the layers.
[0083] Manufacture of Fibrous Substrate Layer, Coating Layer and
Artificial Leather
[0084] Typical steps in the production of artificial leather are
detailed below, together with modifications according to the
present invention.
[0085] 1. Manufacture of Fibrous Substrate Layer
[0086] 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.
[0087] The exemplary artificial leathers depicted in FIGS. 2a to 5
may include a fibrous substrate layer comprising a thermally
conductive material, which may be a silver-coated conductive
materials, a stainless yarn or a surface cool-feeling yarn. These
thermally conductive yarns may be woven together to form the
fibrous substrate layer. Alternatively, these thermally conductive
materials may be inter-woven with other types of yarn such as
polyester yarn, cotton yarn or other yarns to collectively form the
fibrous substrate layer.
[0088] 2. Manufacture of Artificial Leather
[0089] Optionally, the leather may be manufactured by either wet or
dry processing or a combination of both modes as detailed
below.
[0090] Referring to FIG. 6, 100-g PU resin was mixed with 80 g of
DMF (Dimethlyformamide). A thermally conductive material was added
to the mixture at this point, although this may be omitted if
thermally conductive material is included in the substrate. The
resultant paste was applied to the surface of a fibrous substrate
layer 10 which may/may not include thermally conductive material as
detailed above without departing from the present invention.
[0091] 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.
[0092] Alternatively, artificial leather may be produced by dry
processing as shown in FIG. 7.
[0093] Referring now to FIG. 7, 100-g PU resin was mixed with 70 g
of DMF. A thermally conductive material may be optionally added to
the mixture. The resultant paste was applied to a backing paper 30.
The backing paper 30 and the paste was oven dried at 120.degree. C.
for 5 minutes. If desirable an additional (second) layer of PU-DMF
paste may be applied to the surface of the dried PU layer and the
resin layer together with the backing paper 30 is then oven dried.
The cycle may be repeated until a resin coating layer 12 of the
desired thickness is obtained.
[0094] 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.
[0095] In still a further technique artificial leather with a
three-layer structure such as that shown in FIG. 5 may be produced
with a combination of wet and dry processing. The dried resin
coating layer obtained from dry processing was laminated to the
artificial leather obtained from wet processing to give an
artificial leather having two resin coating layers and a fibrous
substrate layer.
[0096] Measurement of Thermal Conductivity
[0097] Method
[0098] 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.
[0099] Results
[0100] 1. Effect of Fiber Material and Fabric Density on the
Thermal Conductivities of Fibrous Substrate Layer
[0101] 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 FIG. 8a. As shown,
the use of surface cool-feeling nylon yarn or silver-coated
conductive yarn for the substrate layer lead to an increase in the
thermal conductivities of the overall substrate layers, as compared
to a substrate layer made solely from cotton yarn.
[0102] 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.
TABLE-US-00001 TABLE 1 Weaving structure of P25S1 and P30S1.
Substrate Weaving Warp Weft Weft yarn layer structure yarn yarn
density P25S1 Plain- 100% cotton 100% cotton 25 layer yarn, black,
yarn and Picks/Inch P30S1 40 silver-coated 30 Picks/Inch conductive
Picks/Inch yarn, 1:1
[0103] The thermal conductivities of P25S1 and P30S1 are shown in
FIG. 8b. It can be seen that an increase in the density of the
woven yarn results in an increase of thermal conductivity. The more
densely packed yarns in P30S1 may exclude more air from the fibrous
structure. The reduction in the amount of trapped air, which is a
good thermal insulator, may account for the increase in thermal
conductivity of P30S1.
[0104] 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.
TABLE-US-00002 TABLE 2 Weaving structure of 30 Polyester, 30 P-S,
30 Silver and 60 Silver. Substrate Weaving Warp Warp Weft Weft
layer structure yarn density yarn density 30 Polyester Plain
Polyester 47 Polyester 30 ends/cm picks/cm 30 P-S Polyester 30 and
picks/cm silver-coated conductive yarn, 1:1 30 Silver silver-coated
30 conductive picks/cm yarn 60 Silver silver-coated 60 conductive
picks/cm yarn
[0105] As seen from FIG. 8c, an increase in the percentage
composition of silver-coated conductive yarn results in an increase
in the thermal conductivity of the fibrous substrate layer. In
addition, the thermal conductivity of the substrate layer can also
be enhanced by weaving the silver-coated conductive yarn in a
higher density to exclude air from the substrate layer.
[0106] 2. Effect of Al.sub.2O.sub.3, AlN and SiC on the Thermal
Conductivities of Resin Coating Layer
[0107] Polyurethane resin coating layers comprising various amounts
of aluminium oxide (Al.sub.2O.sub.3) were prepared.
[0108] The thermal conductivities of the resultant coating layers
are report in FIG. 9a (1, 2, 3, 4 and 5 wt % Al.sub.2O.sub.3), FIG.
9b (3, 6, 9, 12, and 15 wt % Al.sub.2O.sub.3) and FIG. 9c (9, 12,
15, 18 and 21 wt % Al.sub.2O.sub.3). It can be seen that generally
the thermal conductivity of the resin coating layer increases with
the amount of Al.sub.2O.sub.3 present in the layer, notwithstanding
some minor variations which may be due to possible experimental
errors including testing and sampling. The experiment was repeated
using aluminium nitride (AlN) or silicon carbide (SiC) as the
thermally conductive material. The results, as shown in FIG. 10a
(3, 6, 9, 12, and 15 wt % AlN), FIG. 10b (9, 12, 15, 18 and 21 wt %
AlN), FIG. 11a (1, 2, 3, 4 wt % SiC 1500) and FIG. 11b (1, 2, 3, 4,
5 wt % SiC 2000), again indicate that generally the thermal
conductivity of the resin coating layer increases with the amount
of thermally conductive material present in the coating layer.
[0109] 3. Thermal Conductivities of Various Two-Layer Artificial
Leathers
[0110] Artificial leathers were producing with resin coating layers
comprising different concentrations of AL.sub.2O.sub.3 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
FIGS. 12a and 12b.
[0111] By dispersing either AL.sub.2O.sub.3 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.
[0112] Further experiments have also been conducted as shown below,
in which the artificial leather was prepared using the wet method,
at a 30% concentration.
[0113] 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.
TABLE-US-00003 TABLE 3 Specimen Base Layer Resin Layer Sample 1
Polyester 30 Standard industry additives + 30% Al2O3 Sample 2
Polyester - Al2O3 30% in resin layer without industry Silver 30
additives Sample 3 Polyester 30 Standard industry additives + 30%
Al2O3 Sample 4 Polyester - Al2O3 30% in resin layer without
industry Silver 30 additives
[0114] 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.
[0115] 4. Thermal Conductivity of a Three-Layer Artificial
Leather
[0116] A three-layer artificial leather 18 as schematically
illustrated in FIG. 13 was prepared with 60 Silver as the fibrous
substrate layer 10. Successive lamination of a resin coating layer
24 made from wet processing and a resin coating layer 26 made from
dry processing gives the three-layer artificial leather 18. The
resin coating layer 24 made from wet processing contains 20 wt % of
Al.sub.2O.sub.3 and the resin coating layer 26 made from dry
processing contains 20 wt % of Al.sub.2O.sub.3.
[0117] 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 FIG. 14. The three-layer artificial leather
18 showed a 48% increase in thermal conductivity as compared with
the commercially available polyurethane leathers.
[0118] 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 FIG. 15 is used to
supply heat to the three-layer artificial leather 18 and a
commercially available artificial leather. The heat source 100
comprises a power supply 102 for heating up a testing surface 104
on which an artificial leather may be placed. The thermal images of
the three-layer artificial leather 18 and a commercially available
artificial leather were taken by an infrared camera after the
leathers were placed on the heat source for 10 seconds.
[0119] The images are shown in FIG. 16a (commercially available
product) and FIG. 16b (three-layer artificial leather 18). The
three-layer artificial leather 18 reached a significantly higher
temperature than the commercially available artificial leather
after 10 seconds of heating, indicating that the three-layer
artificial leather 18 conducts heat away from the heater more
effectively than the commercially available artificial leather.
[0120] In another thermal imaging experiment, a human body was used
as the heat source. A vest comprising two halves, as shown in FIG.
17, is worn by the human subject. The half of the vest depicted on
the left hand side of FIG. 17 is made from the three-layer
artificial leather 18, and the half of the vest depicted on the
left hand side of FIG. 17 is made from a commercially available
artificial leather 40. The vest was worn for 10 minutes and a
thermal image of the vest was then taken.
[0121] As seen from FIG. 18, the half of the vest that is made from
the three-layer artificial leather 18 reached a higher temperature
than the half that is made from the commercially available
artificial leather 40. The higher temperature of the three-layer
artificial leather portion results from its superior heat
conductivity.
[0122] 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.
[0123] 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.
[0124] 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.
[0125] 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.
[0126] 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.
* * * * *