U.S. patent application number 16/469249 was filed with the patent office on 2019-12-19 for synthetic leather.
This patent application is currently assigned to KYOWA LEATHER CLOTH CO., LTD.. The applicant listed for this patent is KYOWA LEATHER CLOTH CO., LTD.. Invention is credited to Noriyuki ISHIYAMA, Kenji KUBO.
Application Number | 20190382953 16/469249 |
Document ID | / |
Family ID | 62707998 |
Filed Date | 2019-12-19 |
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United States Patent
Application |
20190382953 |
Kind Code |
A1 |
KUBO; Kenji ; et
al. |
December 19, 2019 |
SYNTHETIC LEATHER
Abstract
Provided is a synthetic leather including: a base fabric that
has a limiting oxygen index of 25 or more, and that is a knitted
body of a yarn including a flame-retardant fiber having a limiting
oxygen index of 25 or more, a cellulose-based fiber, and a carbon
fiber; an adhesion layer containing a flame retardant, the adhesion
layer being provided at at least one side of the base fabric; and a
skin layer provided at a side of the adhesion layer opposite from a
side at which the base fabric is provided.
Inventors: |
KUBO; Kenji; (Hamamatsu-shi,
JP) ; ISHIYAMA; Noriyuki; (Hamamatsu-shi,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KYOWA LEATHER CLOTH CO., LTD. |
Hamamatsu-shi, Shizuoka |
|
JP |
|
|
Assignee: |
KYOWA LEATHER CLOTH CO.,
LTD.
Hamamatsu-shi, Shizuoka
JP
|
Family ID: |
62707998 |
Appl. No.: |
16/469249 |
Filed: |
November 9, 2017 |
PCT Filed: |
November 9, 2017 |
PCT NO: |
PCT/JP2017/040468 |
371 Date: |
June 13, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D06N 3/06 20130101; D06N
3/0097 20130101; D06N 3/145 20130101; D06N 2209/067 20130101; D06N
3/0043 20130101; D06N 3/0056 20130101; D06N 3/0095 20130101; D06N
2201/042 20130101; D06N 3/0063 20130101; D06N 3/0034 20130101; D06N
3/02 20130101; D06N 3/0009 20130101; D06N 3/00 20130101; D06N
2201/087 20130101; D06N 2201/0236 20130101; D06N 3/0077 20130101;
D06N 3/0059 20130101; D06N 3/042 20130101; D06N 3/14 20130101; D06N
3/0038 20130101; D06N 2201/0272 20130101; D06N 3/0015 20130101;
D06N 3/183 20130101 |
International
Class: |
D06N 3/00 20060101
D06N003/00; D06N 3/14 20060101 D06N003/14; D06N 3/02 20060101
D06N003/02; D06N 3/04 20060101 D06N003/04; D06N 3/06 20060101
D06N003/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2016 |
JP |
2016-251706 |
Claims
1. A synthetic leather comprising: a base fabric that has a
limiting oxygen index of 25 or more, and that is a knitted body of
at least one yarn, each yarn comprising at least one of a
flame-retardant fiber having a limiting oxygen index of 25 or more,
a cellulose-based fiber, or a carbon fiber, and the base fabric
includes the flame retardant fiber, the cellulose-based fiber, and
the carbon fiber; an adhesion layer containing a flame retardant,
the adhesion layer being provided at at least one side of the base
fabric; and a skin layer provided at a side of the adhesion layer
opposite from a side at which the base fabric is provided.
2. The synthetic leather according to claim 1, wherein the
flame-retardant fiber comprises one or more selected from the group
consisting of an aramid fiber, a meta-aramid fiber, a polyphenylene
sulfide fiber, an acrylic fiber, a vinyl chloride fiber, a polyclar
fiber, a vinylidene chloride fiber, an acrylic-vinyl chloride
copolymer fiber, an acrylic-vinylidene chloride copolymer fiber,
and an a polybenzimidazole fiber.
3. The synthetic leather according to claim 1, wherein the carbon
fiber comprises one or more selected from the group consisting of a
polyacrylonitrile-based fiber, a pitch-based fiber, and a phenolic
fiber.
4. The synthetic leather according to claim 1, wherein: a content
of the carbon fiber is from 20% by mass to 40% by mass with respect
to a total mass of the yarn constituting the knitted body, a
content of the cellulose-based fiber is from 25% by mass to 45% by
mass with respect to the total mass of the yarn constituting the
knitted body, and a total content of the flame-retardant fiber and
the carbon fiber is greater than the content of the cellulose-based
fiber.
5. The synthetic leather according to claim 1, further including an
intermediate layer between the adhesion layer and the skin
layer.
6. The synthetic leather according to claim 5, wherein the
intermediate layer comprises a flame retardant.
Description
TECHNICAL FIELD
[0001] The present invention relates to a synthetic leather.
BACKGROUND ART
[0002] In recent years, in place of natural leathers or fibrous
sheets, synthetic leathers having excellent durability are widely
used for automotive interior parts (such as instrument panels, door
trims, seats, ceilings, or the like), rail vehicles, aircraft
interior parts (such as trims, seats, ceilings, or the like),
furniture, footwear such as shoes, bags, interior and exterior
members for construction, clothing coverings, clothing linings,
wall covering materials, and the like. For example, synthetic
leathers used for aircraft interior parts and automobile interior
parts need to be lightweight, durable, and have favorable fire
resistance. There is a need for synthetic leathers which have a
certain thickness and moderate elasticity in addition to the basic
properties described above and which has a feel close to that of a
natural leather.
[0003] From the viewpoint of favorable dimensional stability and
processability, in general, synthetic leathers include a flexible
resin layer for adjusting elasticity appropriately, and a skin
layer having a leather-like appearance and excellent in abrasion
resistance, at a surface of a fibrous sheet such as a base
fabric.
[0004] With regard to highly airtight aircraft, vehicles,
automobiles, or the like, favorable fire resistance is desired for
synthetic leathers used for interior products. With regard to fire
resistance of the synthetic leathers, it is considered to be
important that a synthetic leather is hard to burn even if it comes
in contact with flames, that, even if a part of a synthetic leather
burns when it comes in contact with flames, the burning does not
spread easily, and that a synthetic leather is hard to generate
smoke when it burns, or the like.
[0005] In highly airtight aircrafts, vehicles, automobiles, or the
like, if a generation of smoke due to fire is considerable, the
view is more likely to be blocked, and the smoke is more likely to
be inhaled. Therefore, for a synthetic leather used for aircraft
interior parts, vehicle interior parts, automobile interior parts,
or the like, in particular, suppression of smoke generation when in
contact with flames is desired, in addition to flame retardancy, as
fire resistance. Suppression of smoke generation and a low smoke
concentration when a synthetic leather is exposed to flames are
important criteria from the viewpoint of securing visibility in a
highly airtight space.
[0006] In order to improve flame retardancy, a synthetic leather
obtained by impregnating a base fabric with a nitrogen-based or
phosphoric acid-based flame retardant has been proposed (see
Japanese Patent Application Laid-Open (JP-A) No. 2006-77349).
[0007] Furthermore, the applicant of the present application has
previously proposed a synthetic leather including a water-based
polyurethane adhesion layer and a water-based polyurethane skin
layer in this order on a synthetic leather base fabric, which is a
knitted body having an interlock knitted structure using a yarn
including a flame-retardant fiber having a limiting oxygen index
(LOI value) of 25 or more and a cellulose-based fiber, the knitted
body having a mass of from 150 g/m.sup.2 to 250 g/m.sup.2, an LOI
value of the knitted body being 25 or more (see Japanese Patent
Application Laid-Open No. 2013-072141).
SUMMARY OF INVENTION
Technical Problem
[0008] However, the synthetic leather described in JP-A No.
2006-77349 has a problem that the finished quality is inferior when
the thickness or strength of a woven fabric or a non-woven fabric
used for the base fabric is not sufficient, in a case in which, for
example, the leather is used for a seat or the like. Furthermore,
since at the time of production, a base fabric is impregnated with
a flame retardant or the like, and then dried and adhered to a
resin layer, the production process is complicated, and there is a
problem that a flame retardant may cause toxic gas or smoke
generated during burning depending on the types of the flame
retardant used.
[0009] Although a synthetic leather described in JP-A No.
2013-072141 has a feel close to that of a natural leather,
favorable durability, processability and flame retardancy, and has
a function of suppressed generation of toxic gas even when burned,
there is still room for improvement in terms of suppression of
smoke generation during burning.
[0010] An object of an embodiment of the invention is to provide a
synthetic leather which is excellent in flame retardancy and which
has a suppressed ability to generate smoke during burning.
Solution to Problem
[0011] Means for solving the above-described problems include the
following embodiments. [0012] [1] A synthetic leather including: a
base fabric that has a limiting oxygen index of 25 or more, and
that is a knitted body of a yarn including a flame-retardant fiber
having a limiting oxygen index (hereinafter, sometimes referred to
as LOI value) of 25 or more, a cellulose-based fiber, and a carbon
fiber; an adhesion layer containing a flame retardant, the adhesion
layer being provided at at least one side of the base fabric; and a
skin layer provided at a side of the adhesion layer opposite from a
side at which the base fabric is provided.
[0013] [2] The synthetic leather according to [1], wherein the
flame-retardant fiber includes one or more selected from the group
consisting of an aramid fiber, a meta-aramid fiber, a polyphenylene
sulfide fiber, an acrylic fiber, a vinyl chloride fiber, a polyclar
fiber, a vinylidene chloride fiber, an acrylic-vinyl chloride
copolymer fiber, and an acrylic-vinylidene chloride copolymer
fiber.
[0014] [3] The synthetic leather according to [1] or [2], wherein
the carbon fiber includes one or more selected from the group
consisting of a polyacrylonitrile (PAN)-based fiber, a pitch-based
fiber, and a phenolic fiber. [0015] [4] The synthetic leather
according to any one of [1] to [3], wherein a content of the carbon
fiber is from 20% by mass to 40% by mass with respect to the total
mass of the yarn constituting the knitted body, a content of the
cellulose-based fiber is from 25% by mass to 45% by mass with
respect to the total mass of the yarn constituting the knitted
body, and a total content of the flame-retardant fiber and the
carbon fiber is greater than the content of the cellulose-based
fiber. [0016] [5] The synthetic leather according to any one of [1]
to [4], further including an intermediate layer between the
adhesion layer and the skin layer. [0017] [6] The synthetic leather
according to [5], wherein the intermediate layer contains a flame
retardant.
Advantageous Effects of Invention
[0018] According to one embodiment of the present invention, a
synthetic leather having favorable flame retardancy and which has a
suppressed ability to generate smoke during burning.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a schematic sectional view showing an embodiment
of a synthetic leather in the disclosure.
[0020] FIG. 2 is a schematic sectional view showing another
embodiment of the synthetic leather in the disclosure.
DESCRIPTION OF EMBODIMENTS
[0021] Hereinafter, the synthetic leather according to the
disclosure will be described in detail by way of specific examples
of embodiments, but the invention is not limited thereto in any
way, and can be implemented with appropriate modifications within
the scope of the object of the invention.
[0022] Herein, numerical ranges indicated using "to" mean a range
including the numerical values described before and after "to" as
the minimum value and the maximum value, respectively.
[0023] Herein, the amount of each component in a composition means,
if a plurality of substances corresponding to each component are
present in the composition, the total amount of the plurality of
substances present in the composition.
[0024] Herein, the term "process" includes not only a process
independent from other processes but also a process which cannot be
clearly distinguished from other processes as long as a desired
purpose of the process can be achieved.
[0025] In each of the drawings, components having the same
reference numerals indicate that they are the same components.
[0026] With regard to the stepwise numerical ranges described
herein, the upper limit value or the lower limit value described in
one numerical range may be replaced with the upper limit value or
the lower limit value of another stepwise numerical range. In the
numerical ranges described herein, upper limit values or lower
limit values of the numerical value ranges may be replaced with
values described in Examples.
[0027] <Synthetic Leather>
[0028] The synthetic leather according to the disclosure includes:
a base fabric that has an LOI value of 25 or more, and that is a
knitted body of a yarn including a flame-retardant fiber having an
LOI value of 25 or more, a cellulose-based fiber, and a carbon
fiber; an adhesion layer containing a flame retardant, the adhesion
layer being provided at at least one side of the base fabric; and a
skin layer provided at a side of the adhesion layer opposite to the
side at which the base fabric is provided.
[0029] A base fabric of a synthetic leather refers to a base
material for forming layers of the synthetic leather, the base
material being a fabric selected from a knitted body, a woven
fabric, a nonwoven fabric, or the like. The base fabric in the
disclosure is a knitted body, that is, a knitted fabric formed by
knitting with fibers.
[0030] [Base Fabric]
[0031] A base fabric used for the synthetic leather according to
the disclosure is a knitted body of a yarn including a
flame-retardant fiber having an LOI value of 25 or more
(hereinafter, sometimes referred to as "flame-retardant fiber"), a
cellulose-based fiber, and a carbon fiber, and has an LOI value of
the base fabric itself, which is a knitted body, of 25 or more.
[0032] A knitted body used for the base fabric is knitted using
including at least three different types of fibers described
above.
[0033] A limiting oxygen index (LOI value) indicates an oxygen
concentration required for a substance to continue burning, and is
measured by the method described in JIS K7201 (2006) (ASTM D2863).
Usually, since the oxygen concentration in the air is about 21.2%,
it can be said that the flame retardancy is favorable when the LOI
value is 25 or more.
[0034] Considering the case in which the base fabric is a base
fabric for a synthetic leather used for interior materials of
vehicles or the like, from the viewpoint of favorable knittability,
and flexibility and durability of a base fabric to be obtained, it
is preferable that a yarn used for knitting the knitted body has a
thickness of about 16 count to 40 count. The term "count" herein
means "cotton yarn count", indicating that one pound of yarn (1 Lb:
0.45259237 kg) has a length of 840 yards (1 yard: 768.096 m). If
one pound of yarn has a length of 1680 yards, it is called 2 count.
Therefore, the smaller the count value is, the thicker the fiber
is.
[0035] 1 tex according to the SI unit system indicates that a 1000
m long yarn has a mass of 1 g. Cotton yarn count can be converted
to tex using the following conversion formula.
1 tex=590.54 count (cotton yarn count) (conversion formula)
[0036] (Flame-Retardant Fiber)
[0037] A flame-retardant fiber used for the base fabric is not
particularly limited as long as the LOI value is 25 or more. A
flame-retardant fiber refers, not to an incombustible fiber, but to
a fiber in which burning does not spread even when, for example, a
fiber or a knitted body of a fiber comes into contact with a flame
thereby being charred or a portion at which the flame came into
contact being burned, and in which the burning stops promptly when
the flame is detached.
[0038] As a flame-retardant fiber, a flame-retardant synthetic
fiber is preferable from the viewpoint of being able to form a soft
and voluminous knitted body. Specific examples of the
flame-retardant fiber that may be used for the base fabric include
an aramid fiber including a meta-aramid fiber, a polyphenylene
sulfide fiber, a polyclar fiber, a vinylidene chloride fiber, an
acrylic-vinyl chloride copolymer fiber, an acrylic-vinylidene
chloride copolymer fiber, a polybenzimidazole fiber, a vinylidene
chloride fiber, and a vinyl chloride-based fiber. A fiber obtained
by subjecting a non-flame retardant fiber to a flame-retardant
processing to adjust the LOI value to 25 or more may be used as a
flame-retardant fiber in the base fabric. Examples of a fiber which
is obtained by the flame-retardant processing to adjust the LOI
value to 25 or more include a flame retardant polynosic fiber, a
flame-retardant polyester fiber, a flame-retardant acrylic fiber,
and a flame-retardant rayon fiber.
[0039] From the viewpoint of simplicity of manufacturing and
suppression of smoke generation, it is preferable to use a
flame-retardant fiber in which the material itself of the fiber is
flame retardant.
[0040] Among the flame-retardant fibers described above, it is
preferable to include one or more selected from the group
consisting of an aramid fiber, a meta-aramid fiber, a polyphenylene
sulfide fiber, an acrylic fiber, a vinyl chloride fiber, a polyclar
fiber, a vinylidene chloride fiber, an acrylic-vinyl chloride
copolymer fiber, and an acrylic-vinylidene chloride copolymer
fiber, from the viewpoint of flame retardancy and preferable
strength and texture when knitted into a base fabric.
[0041] The flame-retardant fiber in the disclosure has an LOI value
of 25 or more. The LOI value of the flame-retardant fiber is
preferably 26 or more, and more preferably 28 or more.
[0042] Considering the case in which the base fabric for synthetic
leather is used for interior materials of vehicles or the like, it
is preferable that the thickness of a yarn including a
flame-retardant fiber used for the knitting of a knitted body is
from about 16 count to 40 count.
[0043] (Cellulose-Based Fiber)
[0044] A cellulose-based fiber used for the base fabric is not
particularly limited, and any known cellulose-based fiber may be
selected and used. Examples of the cellulose-based fiber include
cotton, hemp, cupra, and rayon.
[0045] Among others, from the viewpoint of flexibility of a base
fabric to be obtained, one or more selected from the group
consisting of cotton and rayon is preferred.
[0046] A cellulose-based fiber such as cotton or rayon has an LOI
value of about from 17 to 19 in itself, and can be said to be a
flammable fiber. However, by combining a cellulose-based fiber with
the above-described flame-retardant fiber and a carbon fiber
described below to obtain a knitted body, the knitted body is used
in an embodiment in which the LOI value of the whole base fabric,
which is the knitted body, is 25 or more, while the characteristics
of the cellulose-based fiber is well utilized.
[0047] By including a cellulose-based fiber in a yarn used for
knitting the base fabric, the cellulose-based fiber is carbonized
during burning, and the burning speed of a knitted body can be
delayed.
[0048] (Carbon Fiber)
[0049] A carbon fiber refers to a fiber obtained by subjecting a
carbon fiber precursor such as an organic fiber to heat
carbonization treatment, the fiber having a mass ratio of 90% by
mass or more of carbon to the total mass of the fiber.
[0050] There is no particular limitation on a carbon fiber used for
producing a base fabric of the synthetic leather according to the
disclosure.
[0051] In particular, the carbon fiber preferably includes at least
one selected from the group consisting of a PAN
(polyacrylonitrile)-based carbon fiber in which an acrylic fiber is
used, a pitch-based carbon fiber in which a pitch is used as a raw
material, and a phenolic carbon fiber in which a phenolic resin is
used as a raw material. In other words, the base fabric is
preferably knitted using a spun yarn including one or more selected
from the group consisting of a polyacrylonitrile (PAN)-based fiber,
a pitch-based fiber, and a phenolic fiber as a carbon fiber.
[0052] A carbon fiber mainly contains hydrogen and oxygen derived
from a raw material resin as an element other than carbon. However,
since a carbon fiber does not contain elements such as phosphorus,
it is hard to burn, and there is very little smoke when burned.
Furthermore, since a carbon fiber has high thermal conductivity, by
the base fabric including a carbon fiber, spreading of fire at the
time of ignition is effectively suppressed.
[0053] In the yarn including at least a flame-retardant fiber, a
cellulose-based fiber, and a carbon fiber described above, which is
used for knitting a base fabric, a manner in which each fiber is
included is not particularly limited. For example, a base fabric
may be knitted using three yarns, a yarn including a
flame-retardant fiber, a yarn including a cellulose-based fiber,
and a yarn including a carbon fiber. A base fabric may be knitted
using a blended yarn including two of the three types of fibers and
a yarn including the remaining one. A base fabric may be knitted
using a blended yarn including the three types of fibers described
above.
[0054] In order to obtain an excellent retarding effect on the
burning speed by carbonization of the above-described cellulose
fiber without impairing the flame retardancy of a base fabric, the
cellulose-based fiber is preferably blended with the
flame-retardant fiber and the carbon fiber described above.
[0055] In other words, from the viewpoint of the effect of
retarding the burning speed and the effect of suppressing the
generation of smoke, a yarn used to produce a knitted body is
preferably a blended yarn selected from a blended yarn of a
flame-retardant fiber and a cellulose-based fiber, a blended yarn
of a carbon fiber and a cellulose-based fiber, or a blended yarn of
a flame-retardant fiber, a cellulose-based fiber and a carbon
fiber. Among those, a blended yarn of a flame-retardant fiber, a
cellulose-based fiber, and a carbon fiber is preferable from the
viewpoint that the flame retardancy and the smoke suppression
effect is more favorable.
[0056] By using a yarn including the three types of fibers
described above, a knitted body to be obtained can have an LOI
value of 25 or more.
[0057] The contents of a flame-retardant fiber, a cellulose-based
fiber, and a carbon fiber in a base fabric are appropriately
adjusted such that the LOI value of a knitted body to be obtained
can be 25 or more.
[0058] A base fabric used for the synthetic leather according to
the disclosure is a knitted body knitted with a yarn including a
flame-retardant fiber, a cellulose-based fiber, and a carbon fiber,
the LOI value of the knitted body itself also being 25 or more.
[0059] It is preferable that the content of the carbon fiber with
respect to the total mass of a yarn constituting the knitted body
is from 20% by mass to 40% by mass, and the content of the
cellulose-based fiber with respect to the total mass of a yarn
constituting the knitted body is from 25% by mass to 45% by mass,
and the total content of the flame-retardant fiber and the carbon
fiber is greater than the content of the cellulose-based fiber.
[0060] In other words, from the viewpoint that the flame retardancy
of the base fabric to be obtained becomes more favorable, the total
content of the flame-retardant fiber and the carbon fiber in a
knitted body is preferably more than 50% by mass, and the ratio of
the total amount of the flame-retardant fiber and the carbon fiber
with respect to the total mass of the yarn constituting the knitted
body is from 60% by mass to 90% by mass.
[0061] The content of the carbon fiber with respect to the total
mass of the yarn constituting a knitted body is preferably from 20%
by mass to 40% by mass, and more preferably from 30% by mass to 40%
by mass from the viewpoint of the smoke suppression effect.
[0062] From the viewpoint that the softness and texture of the base
fabric to be obtained are more favorable, the content of the
cellulose-based fiber is preferably from 25% by mass to 45% by
mass, and more preferably from 25% by mass to 40% by mass with
respect to the total mass of the yarn constituting the knitted
body.
[0063] A knitted body preferably has an interlock knitted
structure.
[0064] By making a knitted body, which is a base fabric, into an
interlock knitted structure, texture and elasticity of the
synthetic leather resulting from the base fabric become more
favorable.
[0065] From the viewpoint of elasticity and strength of a base
fabric to be obtained, preferably, the thickness of the yarn used
for knitting a knitted body having an interlock knitted structure
with a yarn including a flame-retardant fiber, a cellulose-based
fiber, and a carbon fiber is about from 20 count to 40 count, and
the yarn density is wale: about from 20 yarns/inch (=25.4 mm) to 50
yarns/inch, and course: about from 15 yarns/inch to 70
yarns/inch.
[0066] The mass of the thus obtained knitted body is preferably in
the range of from 150 g/m.sup.2 to 400 g/m.sup.2, and more
preferably in the range of from 175 g/m.sup.2 to 350 g/m.sup.2.
[0067] There is no particular limitation on the structure of the
knitted body. The knitted body may be made uniform using a blended
yarn obtained by twisting a flame-retardant fiber, a
cellulose-based fiber, and a carbon fiber. The knitted body may be
formed as an interlock knitted structure obtained by using a yarn
made of a flame-retardant fiber, a yarn made of a cellulose-based
fiber and a yarn made of a carbon fiber separately, in which the
flame-retardant fiber and the carbon fiber are mainly exposed on
one side and the cellulose fiber is mainly exposed on the other
side.
[0068] In a case in which an interlock knitted structure is made
using a yarn made of a flame-retardant fiber, a yarn made of a
cellulose-based fiber, and a yarn made of a carbon fiber, flame
retardancy of a specific side may be improved by knitting in such a
manner as to expose a yarn including a flame-retardant fiber and a
yarn including a carbon fiber on a side which requires better flame
retardancy.
[0069] In particular, from the viewpoint that the texture,
specifically the flexibility of a knitted body is more preferable,
a yarn suitable for knitting a base fabric is a twisted yarn
(blended yarn), and also from the viewpoint of improving the flame
retardancy effect, a blended yarn including a flame-retardant
fiber, a cellulose-based fiber, and a carbon fiber is
preferable.
[0070] In other words, in a case in which an interlock knitted
structure is formed using a blended yarn including a
flame-retardant fiber, a cellulose-based fiber, and a carbon fiber,
a favorable texture attributed to the cellulose-based fiber is
obtained; during burning, besides being hard to burn, the
cellulose-based fiber in the blended yarn is carbonized, whereby
the burning speed of the knitted body is lowered; and, by the
presence of a carbon fiber which has high thermal conductivity and
by which the generation of smoke during burning is suppressed, the
flame retardancy of a base fabric and the effect of suppressing
smoke generation during burning become considerable.
[0071] As a preferable aspect of the interlock knitted structure,
mockrody knitting, which is fine interlock knitting; ponterome
knitting, which is one of modified structures of interlock
knitting, and is a structure that alternately repeats interlock
knitting and tacking plain stitch; and the like are preferable from
the viewpoint of favorable strength and elasticity and excellent
processability of a synthetic leather to be obtained.
[0072] For example, in the case of a knitted body having a mockrody
knitted structure, since the structure is interlock knitted and has
a high gauge, the structure is dense, has an appearance resembling
a woven fabric, has a thick feeling, and has a flexibility and
stretchability unique to a knitted body. In the case of a knitted
body in which a base fabric is mockrody knitted, it is preferable
to use a blended yarn of the above-described flame-retardant fiber,
cellulose-based fiber, and carbon fiber. A gauge indicates the
number of meshes per unit length, and a high gauge indicates a high
density knitted body having a large number of meshes per unit
length.
[0073] For example, in the case of a knitted body having a
ponterome knitting, a knitted body can be formed in which a first
yarn is mainly exposed on one side and a second yarn is mainly
exposed on the other side. Therefore, by exposing a yarn made of a
flame-retardant fiber and a carbon fiber on one side, making it a
front side, and making the side on which the flammable
cellulose-based fiber is exposed a back side, for example, a
knitted body in which the cellulose-based fiber is protected by a
layer made of the flame-retardant fiber and the carbon fiber can be
obtained.
[0074] When adopting interlock knitting for knitting a base fabric,
a blended yarn of the same composition may be used, or two types of
blended yarn with different blending ratios may be used. In either
case, by using the three types of fibers in combination, flame
retardancy of the entire base fabric is improved, and generation of
smoke during burning is effectively suppressed.
[0075] Since a knitted body of a yarn including a flame-retardant
fiber, a cellulose-based fiber, which is natural fiber and has
excellent breathability and texture, and a carbon fiber, which has
high strength and flame resistance, high thermal conductivity, and
which is hard to generate smoke even when heated, is used as a base
fabric, a base fabric having excellent strength and texture,
favorable flame retardancy, suppressed ability to generate smoke
and high LOI value can be obtained. Since, in the synthetic leather
according to the disclosure, an adhesion layer further contains a
flame retardant as described later, it is considered that a
combination of the flame retardancy of the base fabric and the
flame retardancy of the adhesion layer provides a synthetic leather
with favorable flame retardancy.
[0076] In the synthetic leather according to the disclosure, in
addition to favorable flame retardancy of a base fabric and
suppressed ability to generate smoke during burning, a synthetic
leather formed using this base fabric is excellent in strength and
processability, since the base fabric is excellent in strength and
elasticity and is flexible.
[0077] The base fabric, which is a knitted body, may be napped on
at least one side. Napping can be formed by a conventional method.
Contacting a napped surface of the base fabric with an adhesion
layer containing a flame retardant described later improves
adhesion, adhesive strength and the like between the base fabric
and the adhesion layer.
[0078] A base material used for the synthetic leather may be a
single-layer base material having only a base fabric, or may be a
base material having a multilayer structure in which base fabric
and a sheet having physical properties according to a desired
purpose are layered.
[0079] Hereinafter, respective layers of the synthetic leather
according to the disclosure are described.
[0080] [Skin Layer]
[0081] Any known skin layer used for a synthetic leather may be
used without limitation for the synthetic leather according to the
disclosure.
[0082] In particular, the skin layer preferably contains a
polyurethane from the viewpoint of excellent scratch resistance and
processability.
[0083] As described in detail below, a skin layer may be formed by
applying a composition for forming a skin layer containing a resin
to the surface of a release agent layer of a temporary support
including the release agent layer, and drying.
[0084] Examples of the polyurethane that may be used for a
composition for forming a skin layer include a polycarbonate-based
polyurethane, a polyether-based polyurethane, a polyester-based
polyurethane, and a modified product thereof, and when long-term
durability is desired, a polycarbonate-based polyurethane is
preferred.
[0085] A polyurethane contained in the composition for forming a
skin layer may be water-based or solvent-based.
[0086] A polyurethane used in the composition for forming a skin
layer may be used alone, or two or more kinds thereof may be used
in combination. When using two or more kinds of polyurethane, for
example, a polycarbonate-based polyurethane, which is a preferable
polyurethane, and a polyurethane other than the polycarbonate-based
polyurethane may be used in combination.
[0087] Examples of the water-based polyurethane include an aquous
polyurethane in which, using a polyether-based polyurethane
(homopolymer), a polycarbonate-based polyurethane (homopolymer), or
a mixture or copolymer of a polyether-based polyurethane and a
polycarbonate-based polyurethane, from 0.01% to 10%, preferably
from 0.05% to 5%, and more preferably from 0.1% to 2% by mass of
carboxyl groups with respect to the polyurethane main agent is
introduced into a part of a molecular chain of the polyurethane
main agent described above. When a carboxyl group is introduced to
the polyurethane main agent in the ranges of the mass ratio
described above, due to the presence of the carboxyl group, the
water-based polyurethane can have sufficient water dispersibility
and dry film-forming properties.
[0088] Examples of the solvent-based polyurethane include at least
one solvent-based polyurethane selected from the group consisting
of a polycarbonate-based polyurethane, a polyether-based
polyurethane, a polyester-based polyurethane, and a modified
product thereof, which is soluble to an organic solvent. The
solvent-based polyurethane may be a one-component system or a
two-component system.
[0089] The skin layer preferably has a crosslinked structure from
the viewpoint that the film strength of the skin layer is more
favorable.
[0090] For example, in an embodiment in which a crosslinked
structure is introduced into an water-based polyurethane, in a case
in which a polyurethane main agent into which a carboxyl group has
been introduced is used, for example, by adding a crosslinking
agent to the composition for forming a skin layer, the carboxyl
group and the crosslinking agent can be reacted to form a
crosslinked structure.
[0091] Examples of the crosslinking agent which may be used for the
composition for forming a skin layer in order to form a crosslinked
structure include a conventionally known crosslinking agent.
Examples thereof include an isocyanate crosslinking agent, an epoxy
crosslinking agent, an aziridine crosslinking agent, a carbodiimide
crosslinking agent, and an oxazoline-based crosslinking agent. In
particular, it is preferable to use a carbodiimide crosslinking
agent from the viewpoint of suppressing hydrolysis of the
polyurethane.
[0092] Examples of an embodiment in which a crosslinked structure
is introduced into a solvent-based polyurethane include an
embodiment in which a solvent-based polyurethane is used as a main
agent and in which polydiisocyanate is used in combination as a
crosslinking component. By using a polydiisocyanate in combination,
a crosslinked structure can be formed by heat curing of the
polyurethane.
[0093] The polyurethane used to form a skin layer is preferably a
polyurethane capable of forming a film having a hardness in the
range of from 2 MPa to 40 MPa, and more preferably in the range of
from 3 MPa to 10 MPa, at 100% modulus as measured according to JIS
K6772 (1994).
[0094] The preferable hardness of the polyurethane used for the
skin layer herein is a hardness after forming a crosslinked
structure in the skin layer.
[0095] A commercially available product may be used as a
polyurethane contained in the composition for forming a skin layer.
Examples of the commercially available product that may be used for
the composition for forming a skin layer include CRISVON
(registered trademark) NY-373 (trade name) manufactured by DIC
Corporation.
[0096] The skin layer may further contain other components in
addition to the resin, which is a main component such as a
polyurethane, and a solvent for dissolving the resin.
[0097] Examples of such other component that may be contained in
the skin layer include the above-described crosslinking agent, a
crosslinking accelerator, a colorant, a brightening agent (such as
a pearlescent agent, or a metallic pigment), a light stabilizer, an
ultraviolet absorber, an antioxidant, a feel improver, a
film-forming aid, a flame retardant, and a blowing agent.
[0098] Examples of the colorant include colored organic resin
particles in which a colorant is contained in organic resin fine
particles selected from urethane-based resin particles, acrylic
resin particles, or silicone-based resin particles. In particular,
it is preferable to include polycarbonate-based colored resin
particles, from the viewpoint of the affinity to the
polyurethane-based resin, which serves as a dispersion medium, and
uniform dispersibility.
[0099] In general, the average particle diameter of organic resin
fine particles used as the colorant is preferably in the range of
from 0.01 .mu.m to 1.0 .mu.m, and more preferably in the range of
from 0.05 .mu.m to 0.8 .mu.m.
[0100] For example, when the skin layer contains a colorant, the
designability of the synthetic leather is improved.
[0101] By adding a known flame retardant such as a
phosphorus-based, halogen-based, or inorganic metal-based flame
retardant to a skin layer, the flame retardancy of the synthetic
leather is further improved.
[0102] The thickness of the skin layer is not particularly limited,
and may be appropriately selected according to the purposes. In
general, from the viewpoint of strength and appearance, the
thickness of the skin layer after drying is preferably about from
10 .mu.m to 50 .mu.m, and more preferably about from 10 .mu.m to 30
.mu.m.
[0103] [Adhesion Layer Containing Flame Retardant]
[0104] The synthetic leather according to the disclosure has an
adhesion layer containing a flame retardant (hereinafter, sometimes
simply referred to as "adhesion layer") provided at a side of the
skin layer at which the base fabric is provided. In other words,
the skin layer is located at a side of the adhesion layer opposite
to the side at which the base fabric is provided.
[0105] An adhesion layer may be formed using a composition for
forming an adhesion layer containing an adhesive and a flame
retardant, as described below.
[0106] A polyurethane adhesive may be used to form an adhesion
layer. Examples of the polyurethane which may be used for formation
of an adhesion layer include a polycarbonate-based polyurethane, a
polyether-based polyurethane, a polyester-based polyurethane, and a
modified product thereof, and when long-term durability is desired,
a polycarbonate-based polyurethane is preferred.
[0107] The polyurethane used for an adhesion layer may also be
water-based or solvent-based, as with the polyurethane used for the
skin layer.
[0108] The polyurethane used to form an adhesion layer is
preferably a polyurethane capable of forming a film having a
hardness in the range of from 2 MPa to 20 MPa, and more preferably
in the range of from 2 MPa to 8 MPa, at 100% modulus as measured
according to JIS K6772 (1994).
[0109] From the viewpoint of further improving the flexibility of
the synthetic leather to be obtained, the polyurethane used for the
adhesion layer is preferably a polyurethane which is equivalent to
a polyurethane used for the skin layer or a polyurethane which is
capable of forming a more flexible film.
[0110] A commercially available polyurethane may be used as a
polyurethane contained in the composition for forming an adhesion
layer. Examples of the commercially available product which may be
used for the composition for forming an adhesion layer include
CRISVON TA205FT manufactured by DIC Corporation.
[0111] (Flame Retardant)
[0112] An adhesion layer contains a flame retardant. The flame
retardant contained in the adhesion layer can further improve the
flame retardancy of the synthetic leather according to the
disclosure. Therefore, the synthetic leather according to the
disclosure is favorably used as interior materials for aircraft,
vehicles, and the like.
[0113] The flame retardant which may be used for the adhesion layer
is not particularly limited, and a known one can be appropriately
used. Examples of the flame retardant include a metal hydroxide, a
phosphorus-based flame retardant, and a nitrogen-phosphorus-based
flame retardant.
[0114] The flame retardant is also available as a commercial
product, and examples thereof include PEKOFLAM (registered
trademark) STC powder manufactured by Archroma Japan K.K.
[0115] The content of the flame retardant is preferably in the
range of from 5 parts by mass to 40 parts by mass with respect to
100 parts by mass of a polyurethane, which is a main component of
the adhesion layer.
[0116] As will be described later, after a skin layer is formed on
a temporary support, a composition for forming an adhesion layer
including a polyurethane and a flame retardant is applied to the
surface of the skin layer and dried by heating, whereby a layer of
a coating liquid for forming an adhesion layer having a desired
thickness is formed.
[0117] After that, thermocompression bonding is performed in such a
manner that the base fabric described above and a layer of the
composition for forming an adhesion layer are in contact with each
other, and an adhesive contained in the layer of a composition for
forming an adhesion layer is reacted and cured, whereby formation
of an adhesion layer and adhering of the adhesion layer and the
base fabric are performed simultaneously, and then, a temporary
support is peeled off, and a synthetic leather can be obtained.
[0118] A crosslinking agent and a crosslinking accelerator may be
added to the adhesion layer for the purpose of improving the
curability.
[0119] The crosslinking agent and the crosslinking accelerator are
selected according to the type of the polyurethane used in the
adhesion layer. Examples of the crosslinking agent and the
crosslinking accelerator that may be used for the composition for
forming an adhesion layer include the same ones as those described
in the composition for forming a skin layer described above.
[0120] The crosslinking agent may be used in combination with a
crosslinking accelerator suitable for the crosslinking agent.
[0121] The content of the crosslinking agent in the composition for
forming an adhesion layer may be appropriately selected in
consideration of the strength, flexibility and the like required
for the adhesion layer.
[0122] The thickness of the adhesion layer after drying is
preferably about from 20 .mu.m to 100 .mu.m, and more preferably in
the range of from 30 .mu.m to 80 .mu.m. When the thickness of the
adhesion layer is in the above-described ranges, a synthetic
leather having sufficient elasticity and strength is formed.
[0123] The synthetic leather according to the disclosure may
include another layer in addition to the base fabric, the adhesion
layer, and the skin layer, as long as an effect is not impaired.
Examples of another layer include an intermediate layer and a
surface treatment layer.
[0124] [Intermediate Layer]
[0125] Depending on the purposes, such as to further improve the
strength of a skin layer or to improve the flexibility and
cushioning properties of a synthetic leather, the synthetic leather
according to the disclosure may include an intermediate layer
between the skin layer and the adhesion layer described above.
[0126] There are no particular restrictions on the configuration of
the intermediate layer. From the viewpoint of strength and
flexibility, an intermediate layer containing a polyurethane is
preferred.
[0127] The polyurethane used for the intermediate layer may be
water-based or solvent-based, as with the polyurethane used for the
skin layer.
[0128] The polyurethane used to form the intermediate layer is
preferably a polyurethane capable of forming a film having a
hardness in the range of from 2 MPa to 20 MPa, and more preferably
in the range of from 3 MPa to 10 MPa, at 100% modulus as measured
according to JIS K6772 (1994).
[0129] The intermediate layer may be a resin layer containing air
bubbles, for example, a polyurethane resin intermediate layer
containing air bubbles, for the purpose of improving cushioning
properties and the like.
[0130] The polyurethane that may be used to form an intermediate
layer may be a commercially available product. Examples of the
commercially available polyurethane which may be used for formation
of an intermediate layer include CRISVON TK1015T manufactured by
DIC Corporation.
[0131] The thickness of the intermediate layer may be appropriately
adjusted according to the purposes. In general, the thickness of
the intermediate layer after drying is preferably from 30 .mu.m to
350 .mu.m, and more preferably from 50 .mu.m to 250 .mu.m.
[0132] The intermediate layer may further contain a component such
as a film-forming aid, a pigment, a flame retardant, a filler, an
antiaging agent, an ultraviolet light absorbent, and an aromatic
agent.
[0133] In particular, when the synthetic leather according to the
disclosure has an intermediate layer, the intermediate layer
preferably contains a flame retardant. When both an adhesion layer
and an intermediate layer contain a flame retardant, the flame
retardancy of the synthetic leather is further improved.
[0134] [Layer Structure of Synthetic Leather]
[0135] Examples of the layer structure of the synthetic leather
according to the disclosure will be described with reference to the
drawings.
[0136] FIG. 1 is a schematic sectional view showing an embodiment
of a synthetic leather 10 of the invention.
[0137] The synthetic leather 10 of an embodiment (sometimes
referred to as first embodiment) shown in FIG. 1 includes: the
above-described base fabric 12; an adhesion layer 14 containing a
flame retardant provided at one side of the base fabric 12; and a
skin layer 16 provided at a side of the adhesion layer 14 opposite
to the side at which the adhesion layer 14 is in contact with the
base fabric 12. Herein, the expression that the synthetic leather
10 includes a base fabric 12, an adhesion layer 14, and a skin
layer 16 means that the adhesion layer 14 and the skin layer 16
exist in this order from the base fabric 12 side, and does not
exclude the presence of another layer optionally provided.
[0138] The method of producing the synthetic leather according to
the disclosure is not particularly limited, and a known production
method may be applied as appropriate.
[0139] Hereinafter, a preferred method of producing a synthetic
leather will be described by taking a synthetic leather having a
layer structure shown in FIG. 1 as an example.
[0140] [Formation of Skin Layer]
[0141] A skin layer may be obtained by applying a composition for
forming a skin layer containing a resin, preferably a polyurethane
to the surface of a release agent layer of a temporary support
including the release agent layer with, for example, a closed or
open coating head, forming a layer of a composition for forming a
skin layer, and drying the layer of a composition for forming a
skin layer by heating.
[0142] The skin layer can be formed to have a desired thickness by
adjusting the formulation of the composition for forming a skin
layer, the amount of application, and the like.
[0143] Examples of the temporary support used for forming a skin
layer include a temporary support including a release agent layer
on the surface, and including a desired embossed type (concave and
convex pattern) formed on the surface on which the skin layer is to
be formed.
[0144] For example, when producing a synthetic leather provided
with a skin layer having a natural leather-like appearance, a
leather-like concavo-convex pattern may be preformed on the surface
of a temporary support on which a release agent layer is to be
formed. By using a temporary support having a concavo-convex
pattern formed on the surface as a temporary support, and applying
a composition for forming a skin layer to the surface of the
temporary support on which a release agent layer has been formed,
the leather-like concavo-convex pattern preformed on the temporary
support is transferred to the formed skin layer, and after peeling
off the temporary support, the skin layer having the concavo-convex
pattern is formed in a direction.
[0145] A method of forming a concavo-convex pattern on a skin layer
is not limited to the above, and for example, it is also possible
to form a concavo-convex pattern by conducting embossing when
thermocompression of a plurality of layers including a skin layer
is carried out.
[0146] A polyurethane that may be used for the composition for
forming a skin layer is as described above.
[0147] The application amount and the film thickness of a skin
layer are not particularly limited, and appropriately selected
depending on the purposes. In general, from the viewpoint of
strength and appearance, the thickness of the skin layer after
drying is preferably about from 10 .mu.m to 50 .mu.m, and more
preferably about from 10 .mu.m to 30 .mu.m.
[0148] [Formation of Adhesion Layer Containing Flame Retardant]
[0149] An adhesion layer is provided at a surface of the formed
skin layer. The adhesion layer is provided at a surface of the skin
layer opposite to the surface on which a concavo-convex pattern is
formed.
[0150] After the skin layer is formed on the temporary support, a
composition for forming an adhesion layer containing a polyurethane
and a flame retardant is applied to the surface of the skin layer
with a closed or open coating head to form a layer of a composition
for forming an adhesion layer, which is dried by heating to form a
layer of a coating liquid for forming an adhesion layer having a
desired thickness.
[0151] After that, the above-described base fabric and the layered
body including the skin layer and the layer for a composition for
forming an adhesion layer formed on the temporary support are
layered such that the side to which the layer of a composition for
forming an adhesion layer is applied to comes into contact with the
base fabric, and are thermocompression bonded, whereby the adhesive
contained in the layer of a composition for forming an adhesion
layer is reacted and cured, performing formation of an adhesion
layer and adhering of the adhesion layer and the base fabric
simultaneously. Thereafter, the temporary support is peeled off,
whereby a synthetic leather is obtained.
[0152] The heating temperature and heating time for accelerating
the curing reaction at the time of curing the layer of a
composition for forming an adhesion layer to form an adhesion layer
are appropriately selected depending on the type of an adhesive
contained in the composition for forming an adhesion layer. In
general, the heating temperature is preferably in the range of from
30.degree. C. to 80.degree. C., and the heating time is preferably
in the range of from 12 hours to 72 hours.
[0153] When thermocompression bonding is performed, lamination is
preferably performed at a heating temperature in the range of from
100.degree. C. to 150.degree. C. with a known device such as a roll
nip device.
[0154] In a case in which the base fabric is napped on at least one
side, by tightly adhering the napped side to the layer of a coating
liquid for forming an adhesion layer, the nap of the base fabric
infiltrates the layer of a coating liquid for forming an adhesion
layer. Since the adhesion layer is cured in this state, adhesion
between the base fabric and the adhesion layer is further
improved.
[0155] As described above, in an example of a preferred method of
producing a synthetic leather, by forming a layered body of a skin
layer and a layer of a composition for forming an adhesion layer on
a temporary support, tightly adhering and fixing the adhesion layer
and a base fabric by curing the layer of a composition for forming
an adhesion layer, and then peeling off the temporary support
including a release layer, a synthetic leather having favorable
elasticity, strength and flame retardancy with a suppressed ability
to generate smoke during burning, such as a synthetic leather
having the layer structure illustrated in FIG. 1, can be
obtained.
[0156] FIG. 2 is a schematic sectional view showing a synthetic
leather (sometimes referred to as "second embodiment") 20 in
another embodiment of the invention.
[0157] In the synthetic leather 20 according to the second
embodiment, an intermediate layer 18 is provided between the
adhesion layer 14 and the skin layer 16. By optionally providing
the intermediate layer 18 between the adhesion layer 14 and the
skin layer 16 according to the manner in which the synthetic
leather is used, elasticity, flexibility, shape followability, and
the like of the synthetic leather 20 becomes more favorable.
[0158] [Formation of Intermediate Layer]
[0159] There are no particular restrictions on the structure of the
intermediate layer. From the viewpoint of strength and flexibility,
an intermediate layer containing a polyurethane is preferred.
[0160] An intermediate layer may be obtained by, after the skin
layer is formed on the temporary support as described above,
applying a composition for forming an intermediate layer,
preferably including a polyurethane, to the side of the skin layer
opposite to the side at which the temporary support is located, to
form a layer of a composition for forming an intermediate layer,
drying the layer of a composition for forming an intermediate layer
by heating, whereby a layered body having a skin layer and an
intermediate layer on the temporary support can be formed. The
application and drying of the composition for forming an
intermediate layer may be repeated twice or more to form an
intermediate layer having a desired thickness.
[0161] The intermediate layer may be a polyurethane intermediate
layer containing air bubbles for the purpose of improving
cushioning properties and the like. An example of a method of
forming a polyurethane intermediate layer containing air bubbles
will be described.
[0162] For example, by using a solvent and a thickener as
appropriate for the composition for forming an intermediate layer
containing a polyurethane to adjust the viscosity, and mechanically
generating foams by stirring, a creamy composition for forming an
intermediate layer containing air bubbles can be prepared. By
applying the obtained creamy composition for forming an
intermediate layer to the skin layer described above to form a
layer of a composition for forming an intermediate layer containing
air bubbles, and drying and curing the formed layer, a polyurethane
intermediate layer containing air bubbles can be formed.
[0163] The composition for forming an intermediate layer to be
mechanically foamed may contain a foaming agent, a foam stabilizer,
a crosslinking agent, a thickener, and the like.
[0164] By using a commonly used batch stirrer such as a Hobart
mixer or a hopper, the composition for forming an intermediate
layer can be mechanically stirred while involving air, thereby
obtaining a mechanically-foamed creamy composition for forming an
intermediate layer. In mass production, it is possible to adopt a
method of obtaining a mechanically-foamed creamy composition for
forming an intermediate layer by continuously stirring while
feeding a certain amount of air using an oakes mixer, a pin mixer,
or the like.
[0165] When applying the mechanically-foamed creamy composition for
forming an intermediate layer to the skin layer, a known coating
apparatus such as a knife coater, a comma coater, a roll coater, a
lip coater which is generally used can be employed.
[0166] Examples of another method of forming a polyurethane
intermediate layer which contains air bubbles include a method in
which a chemical blowing agent, such as a thermal expansion
microcapsule, 4,4''-oxybis (benzenesulfonyl hydrazide),
azodicarbonamide, or sodium hydrogen carbonate, is included in the
composition for forming an intermediate layer, which is applied to
the above-described skin layer, and then heat-dried so that the
chemical blowing agent generates air bubbles, thereby forming an
intermediate layer containing bubbles.
[0167] A synthetic leather having a layer structure illustrated in
FIG. 2 can be obtained by applying, in the same manner as in the
first embodiment described above, a composition for forming an
adhesion layer to a side of the formed intermediate layer opposite
to the side at which the skin layer is provided to form a layer of
a composition for forming an adhesion layer, tightly adhering a
base fabric and a face of the formed layer of a composition for
forming an adhesion layer, curing the layer of a composition for
forming an adhesion layer, and then peeling off the temporary
support.
[0168] In a case in which a chemical blowing agent is used, the
composition for forming an intermediate layer may contain, in
addition to the chemical blowing agent, a foaming agent, a foam
stabilizer, a crosslinking agent, a thickener, or the like.
[0169] The composition for forming an intermediate layer may
further contain a component such as a film-forming aid, a pigment,
a flame retardant, a filler, an antiaging agent, an ultraviolet
light absorbent, and an aromatic agent.
[0170] [Formation of Other Layer]
[0171] The synthetic leather according to the disclosure may be
provided with another layer in addition to the above-described skin
layer, adhesion layer, and optionally provided intermediate layer
provided at at least one side of the base fabric, as long as an
effect of the disclosure is not impaired.
[0172] Formation of a surface treatment layer, which is an example
of another layer, will be described below.
[0173] (Surface Treatment Layer)
[0174] A surface treatment layer can be formed by applying a
surface treatment agent composition containing an water-based
emulsion resin or an organic solvent-based surface treatment agent
composition to the surface of the skin layer described above.
[0175] The resin used to form the surface treatment layer is not
particularly limited, and any resin may be used depending on the
purposes. As an example of the resin used for forming a surface
treatment layer, a polyurethane, an acryl, an elastomer, or the
like is preferable, and a polyurethane is more preferable.
[0176] By forming a surface treatment agent layer at the surface of
a skin layer, the appearance of the synthetic leather is further
improved.
[0177] The surface treatment layer may contain a crosslinking
agent, an organic filler, a lubricant, a flame retardant, or the
like. For example, by including an organic filler, a lubricant, or
the like in the surface treatment layer, a smooth feel is imparted
to the skin material, and abrasion resistance is further
improved.
[0178] The synthetic leather according to the disclosure is
excellent in durability and flame retardancy since the synthetic
leather is provided with a base fabric with a suppressed ability to
generate smoke during burning and an adhesion layer containing a
flame retardant. Therefore, the synthetic leather can be used
suitably for various fields such as automotive interior materials,
railway vehicle interior parts, aircraft interior parts, furniture,
shoes, footwear, bags, interior and exterior members for
construction, clothing coverings, and clothing lining. Further, the
synthetic leather exhibits an effect of, in the case of covering
the surface of a member having a complex three-dimensional shape
such as a seat or a chair, achieving similar feel and appearance as
in the case of using a natural leather.
EXAMPLES
[0179] Hereinafter, the embodiments described above will be more
specifically described by way of Examples. However, the invention
is not limited to the following Examples, and various modifications
can be made as long as they do not depart from the spirit of the
invention.
Example 1
[0180] Using a blended yarn of 22 count in thickness obtained by
spinning three kinds of fibers, which are: polyvinylidene
chloride-acrylic copolymer fiber (LOI value: 33), which is a flame
retardant; a rayon fiber (LOI value: 19), which is a
cellulose-based fiber; and a phenolic carbon fiber, which is carbon
fiber (LOI value: 33), a knitted body (knitted fabric), having a
knitting structure of mockrody, a thickness of 0.9 mm, and a weight
of 310 g/m.sup.2, was manufactured, whereby a base fabric was
obtained. The blending ratio of the polyvinylidene chloride fiber,
the rayon fiber, and the phenolic carbon fiber was 35:35:30 by mass
ratio.
[0181] The LOI value of the obtained base fabric measured in
accordance with JIS K7201 (2006) was 37.
[0182] As a temporary support, a patterned release paper which has
been release-treated on the surface and has a release layer
(manufactured by Dai Nippon Printing Co., Ltd., DE-41: average
paper thickness of 140 .mu.m) was used.
[0183] (Composition for Forming Skin Layer)
[0184] Non-yellowing polycarbonate-based urethane resin with 100%
modulus of 5 MPa (manufactured by DIC Corporation, CRISVON NY327:
trade name): 100 parts by mass
[0185] Colored organic resin fine particles (DIC Corporation, Dirac
(registered trademark) color series): 18 parts by mass
[0186] Solvent (mixed solvent of N,N-dimethylformamide (DMF) and
isopropanol (IPA) in a mass ratio of 80:20): 36 parts by mass
[0187] The above composition for forming a skin layer was
sufficiently mixed, and a composition for forming a skin layer was
obtained.
[0188] The composition for forming a skin layer was applied to the
surface of the temporary support having a release layer, at the
side of the release layer in an amount by which the film thickness
after drying became about 30 .mu.m using an open coating head
coating apparatus. The coating film was dried with hot air using a
hot air drier at 100.degree. C. for 2 minutes to form a skin layer
on the temporary support. By visually observing the obtained skin
layer, it was confirmed that the skin layer was uniform without
pinholes.
[0189] (Composition for Forming Adhesion Layer)
[0190] Non-yellowing polycarbonate-based polyurethane adhesive with
100% modulus of 2.5 MPa (manufactured by DIC Corporation, CRISVON
TA205FT: trade name): 100 parts by mass
[0191] Non-Deca BDE-based halogen-based flame retardant
(combination with antimony) (manufactured by Marubishi Oil Chemical
Corporation, NONNEN (registered trademark) SAN-2: trade name): 20
parts by mass
[0192] Solvent (mixed solvent of DMF and methyl ethyl ketone (MEK)
with a mass ratio of 85:15): 65 parts by mass
[0193] Crosslinking agent (manufactured by DIC Corporation, BURNOCK
(registered trademark) DN950: trade name): 10 parts by mass
[0194] The components of the composition for forming an adhesion
layer were sufficiently mixed, and a composition for forming an
adhesion layer was obtained.
[0195] On the surface of the temporarily formed skin layer at the
side opposite to the side at which the temporary support was
placed, the composition for forming an adhesion layer was applied
in an amount by which the film thickness after drying became 50
.mu.m using an open coating head, and was dried at 100.degree. C.
for 2 minutes to form a layer of a coating liquid for forming an
adhesion layer, whereby a layered body for forming a synthetic
leather was obtained.
[0196] Next, a base fabric and the layer of a coating liquid for
forming an adhesion layer of the layered body for forming a
synthetic leather were brought into contact with each other, which
were then laminated by a nip device, were wound up, and were
maintained at a temperature of 50.degree. C. for 48 hours to allow
the curing reaction of the adhesive contained in the layer of a
coating liquid for forming an adhesion layer to proceed, whereby an
adhesion layer tightly adhered to the base fabric was formed.
[0197] After that, the temporary support was peeled off, and a
synthetic leather of Example 1, including an adhesion layer and a
skin layer in this order at the surface of the base fabric, was
obtained.
[0198] The obtained synthetic leather of Example 1 was visually
observed. As a result, it was confirmed that there was no pattern
loss due to emboss transfer failure, that the appearance was
excellent, and that the elasticity and feel upon pressing the
synthetic leather with a finger were favorable.
Example 2
[0199] A skin layer was temporarily formed on a release paper in
the same manner as in Example 1.
[0200] Next, components of the following formulation were
sufficiently mixed, and a composition for forming an intermediate
layer was prepared.
(Composition for Forming Intermediate Layer)
[0201] Non-yellowing polycarbonate-based urethane resin with 100%
modulus of 5 MPa (manufactured by DIC Corporation, CRISVON
TK1015T): 100 parts by mass
[0202] Thermally expandable beads (Japan Fillite Co., Ltd.,
EXPANCEL 920DU120): 4 parts by mass
[0203] Amine chain extender (BASF Japan Ltd., LAROMIN (registered
trademark) C260): 4.6 parts by mass
[0204] Colored organic resin fine particles (manufactured by DIC
Corporation, DAILAK COLOR SERIES): 5 parts by mass
[0205] Phosphorus-based flame retardant (manufactured by Archroma
Japan K.K., PEKOFLAM (registered trademark) ATC powder): 30 parts
by mass
[0206] Solvent (mixed solvent of DMF, 1-methoxy-2-propanol (PGM),
and ethyl acetate with a mass ratio of 24:38:38): 52 parts by
mass
[0207] On the surface of the temporarily formed skin layer
described above at the side opposite to the side at which the
temporary support was placed, the obtained composition for forming
an intermediate layer was applied in an amount by which the film
thickness after drying became 200 .mu.m using an open coating
coater. The coated film was dried with hot air at 170.degree. C.
for 2 minutes using a hot air dryer, by which thermally expandable
beads were expanded, whereby an intermediate layer containing air
bubbles was formed on the skin layer.
[0208] A layer of a coating liquid for forming an adhesion layer
was formed on the surface of the formed intermediate layer opposite
to the side at which the skin layer is provided in the same manner
as in Example 1, whereby a layered body for forming a synthetic
leather was obtained.
[0209] Next, a base fabric, which is the same base fabric as used
in Example 1, and the layer of a coating liquid for forming an
adhesion layer of the obtained layered body for forming a synthetic
leather were brought into contact with each other, and after drying
of the layer of a coating liquid for forming an adhesion layer, the
layered body was tightly adhered to the base fabric by
thermocompression. In this manner, a synthetic leather of Example
2, which further includes an intermediate layer containing air
bubbles in the synthetic leather of Example 1, was obtained.
[0210] The obtained synthetic leather of Example 2 was excellent in
appearance, and the elasticity and feel upon pressing the synthetic
leather with a finger were even more favorable than those of the
synthetic leather of Example 1.
Comparative Example 1
[0211] A synthetic leather of Comparative Example 1 was produced in
the same manner as in Example 1 except that a base fabric obtained
by knitting in the same manner as in the base fabric in Example 1,
using a 22 count blended yarn obtained by spinning two types of
fibers, which are: polyvinylidene chloride-acrylic copolymer fiber
(LOI value: 33), which is a flame retardant; and a rayon fiber (LOI
value: 19), which is a cellulose-based fiber, at a mass ratio of
65:35, was used instead of the base fabric used in Example 1.
Comparative Example 2
[0212] A synthetic leather of Comparative Example 2 was produced in
the same manner as in Example 1 except that a base fabric obtained
by knitting in the same manner as in the base fabric in Example 1,
using a 22 count yarn consisting only of a polyvinylidene
chloride-acrylic copolymer fiber (LOI value: 33), which is a flame
retardant, was used instead of the base fabric used in Example
1.
[0213] (Evaluation of Obtained Synthetic Leather)
[0214] The obtained synthetic leather was evaluated by the
following method. The results are shown in Table 1 below.
1. Flame Retardancy Evaluation
[0215] The respective synthetic leathers obtained were subjected to
a burning test according to the Airworthiness Standards, Part III,
Appendix F, Vertical Method, and flame retardancy was evaluated
according to the criteria 1-1 to 1-3 shown below.
[0216] Using criteria 1-1 to 1-3 below, flame retardancy was
evaluated as A if all the categories fell within rank A, and the
flame retardancy was evaluated as B if two of the categories fell
within rank A and no category fell within the rejection level. When
the flame retardancy shown in Table 1 was evaluated as A or B, it
is concluded that the flame retardancy sufficient for practical use
is exhibited.
1-1. Burning Time
[0217] The time for which burning lasted after ignition was
measured. According to the Standards, cases in which burning stops
within 15 seconds are considered to be acceptable. [0218] A:
Burning time is 5 seconds or less. [0219] B: Burning time is from
more than 5 seconds to 10 seconds. [0220] C: Burning time is from
more than 10 seconds to 15 seconds. [0221] D: Burning time is more
than 15 seconds (rejection level).
1-2. Burning Length
[0222] The length of burning spreading from the ignition site was
measured. According to the Standards, 20 cm or less is considered
to be acceptable. [0223] A: Burning length is 15 cm or less. [0224]
B: Burning length is more than 15 cm to 20 cm. [0225] C: Burning
length is more than 20 cm (rejection level).
1-3. Burning Time of Falling Objects
[0226] The time for which the burning of falling objects from the
ignited point lasted was measured. According to the Standards, it
is considered to be acceptable if the burning stops within 5
seconds. [0227] A: Falling objects do not burn, and burning stops
immediately. [0228] B: Burning time of falling objects is 5 seconds
or less. [0229] C: Burning time of falling objects is more than 5
seconds (rejection level).
[0230] 2. Test for Smoke Generation Property
[0231] A test for smoke generation property of the synthetic
leathers was performed by the measurement according to BSS 7238,
Flame Method (measurement of the smoke specific optical density of
aircraft interior materials, standards of Boeing Company) using a
smoke chamber, and evaluation was performed according to the
following criteria. If the smoke concentration was 100 or less, the
smoke generation property was evaluated as acceptable for practical
use.
(Evaluation Criteria)
[0232] A: Smoke concentration is 80 or less. [0233] B: Smoke
concentration is more than 80 to 100. [0234] C: Smoke concentration
is more than 100.
[0235] 3. Anti-Fire Spreading Property
[0236] When a base fabric of a synthetic leather is melted and a
hole is formed in the base fabric upon burning, burning of a
polyurethane or the like used for an adhesion layer, an
intermediate layer or the like of the synthetic leather is
promoted. Therefore, a burning test was conducted from the skin
layer side of the synthetic leathers, and evaluation as to whether
or not a hole was formed in the base fabric upon burning was
performed.
(Evaluation Criteria)
[0237] A: The burning point of a base fabric is carbonized, and a
hole is not formed. [0238] B: The burning point of a base fabric is
melted, and a hole is formed (rejection level).
[0239] 4. Scratch Resistance
[0240] The scratch resistance at the side of the skin layer of the
synthetic leathers was tested using Taber type Scratch Tester
(manufactured by TESTER SANGYO Co., Ltd., HA-201) in accordance
with the method described in JIS K6253 (2006), and evaluation was
performed according to the following criteria. The required
performance for scratch resistance is 2.94 N or more.
(Evaluation Criteria)
[0241] A: 2.94 N or more [0242] B: less than 2.94 N
TABLE-US-00001 [0242] TABLE 1 Base fabric for synthetic leather
Evaluation results Flame-retardant Cellulose- Thickness of Smoke
Anti-fire fiber based fiber Carbon fiber yarn for Base fabric Flame
generation spreading Scratch (LOI value) (LOI value) (LOI value)
base fabric (LOI value) retardancy property property resistance
Example 1 Polyvinylidene Rayon fiber Phenolic carbon 22 count
(blended 37 A A A A chloride-acrylic (19) fiber (33) yarn of 3
types of copolymer fiber (33) fibers) Example 2 Polyvinylidene
Rayon fiber Phenolic carbon 22 count (blended 37 A A A A
chloride-acrylic (19) fiber (33) yarn of 3 types of copolymer fiber
(33) fibers) Comparative Polyvinylidene Rayon fiber -- 22 count
(blended 35 A B A A Example 1 chloride-acrylic (19) yarn of 2 types
of copolymer fiber (33) fibers) Comparative 22 count -- -- 22 count
(blended 33 A C B A Example 2 Polyvinylidene yarn of 1 type of
chloride-acrylic fiber) copolymer fiber (33)
[0243] From the results shown in Table 1, it is understood that the
synthetic leathers of Example 1 and Example 2 are excellent in all
of the flame retardancy, the anti-fire spreading property, and the
scratch resistance, and have a suppressed ability to generate smoke
upon burning, whereby visibility during burning is expected to be
secured. Therefore, it can be understood that the synthetic
leathers can be suitably used for aircraft seat materials, vehicle
interior materials, furniture, and the like, which are required to
have flame retardancy and durability.
[0244] On the other hand, the synthetic leather of Comparative
Example 1 using a flame-retardant fiber and a cellulose-based fiber
as the base fabric was slightly inferior to Examples in suppressing
the generation of smoke upon burning, and Comparative Example 2
using only a flame-retardant fiber had inferior anti-fire spreading
property compared to Example 1, and the smoke generation property
was also at a level that would cause problems in practical use.
[0245] The disclosure of Japanese Patent Application No.
2016-251706 filed on Dec. 26, 2016 is hereby incorporated by
reference.
[0246] All Documents, Patent Applications, and technical standards
described herein are incorporated by reference herein to the same
extent as if each of the Documents, Patent Applications, and
technical standards had been specifically and individually
indicated to be incorporated by reference.
* * * * *