KIM, Kwang-Oh (Daewoo apt, Gupyeong-dong Gumi-city, Gyeongsangbuk-do 730-755, 106-1506, KR)
LEE, Sang-Mok (77 Doryang-dong, Gumi-city, Gyeongsangbuk-do 730-020, KR)
YOUN, Jung-Hoon (Daedong Town 1-cha 101-308, Otae-dong Gumi-city, Gyeongsangbuk-do 730-140, KR)
KIM, Kwang-Oh (Daewoo apt, Gupyeong-dong Gumi-city, Gyeongsangbuk-do 730-755, 106-1506, KR)
LEE, Sang-Mok (77 Doryang-dong, Gumi-city, Gyeongsangbuk-do 730-020, KR)
WHAT IS CLAIMED IS:
1. An inflatable fabric comprising at least a separate area of two
separated fabric layers which are woven at the same time using a weaving
machine, and at least one attachment area where a single layer of fabric is
formed, wherein said attachment area is formed from at least a weave
pattern of at least 13 yarns selected from the group consisting of a 2/2
basket weave pattern, a satin weave pattern, a partial attaching weave of a
double layer weave pattern, a plain weave pattern, and a combination
thereof.
2. The inflatable fabric of claim 1 , which comprises the separator
area (A, B) consisting of two separated fabric layers with a plain weave
pattern and an attachment area (C) where a single layer of fabric is formed,
wherein the left separator area (A) and the right separator area (B) of said
separator area (A, B) located at the left and right sides of said attachment
area, respectively, have an the same weave pattern, and said attachment
area (C) is formed from at least a pattern of 13 to 50 yarns selected from the
group consisting of a 2/2 basket weave pattern, a satin weave pattern, a
partial attaching weave of a double layer weave pattern, a plain weave
pattern, and a combination thereof.
3. The inflatable fabric of claim 1 , wherein said attachment area is
formed from a combination weave pattern comprising at least two weave
pattern selected from the group consisting of a 2/2 basket weave pattern, a
satin weave pattern, a partial attaching weave of a double layer weave
pattern, and a plain weave pattern of at least 13 yarns.
4. The inflatable two-layer fabric of claim 1 , wherein said attachment
area is formed from a combination weave pattern of at least 13 yarns
comprising a partial attaching weave of a double layer weave pattern in the
middle of the attachment area and at least one pattern selected from the
group consisting of a 2/2 basket weave pattern, a satin weave pattern, and
a plain weave pattern on either side of the attachment area
5. The inflatable fabric of claim 1 , wherein said attachment area has
air leakage per unit length (measured at a pressure of 2.5 kPa) of less than
0.8 ^ /min cm.
6. The inflatable fabric of claim 1 , which has a stiffness value equal
to or smaller than 3.5 kgf.
7. The inflatable fabric of claim 1 , wherein each single fabric layer of
two-layer fabrics in the separate area has a thickness equal to or less than
0.5 mm.
8. The inflatable fabric of claim 1 , wherein each single fabric layer of
two-layer fabrics in the separate area has a cover factor, defined by the
following Equation 1 , that is equal to or greater than 1900:
Equation 1
Cover factor (CF) = warp density (number/inch) * SQRT (warp
denier) + weft density (number/inch) x SQRT (weft denier).
9. The inflatable fabric of claim 1 , wherein the inflatable fabric has an
inner pressure 5 seconds after an initial pressure of 50 kPa has been
applied that is equal to or greater than 6 kPa, a seam strength at the
attachment area equal to or greater than 80 kg/in, a breaking modulus of
less than 60% and a strength maintenance ratio equal to or greater than
80%.
10. The inflatable fabric of claim 1 , which is coated with a synthetic resin.
11. The inflatable fabric of claim 10, wherein the coating amount on
one side of said the inflatable fabric ranges from 40 g/m 2 to 150 g/m 2 .
12. A car airbag comprising the inflatable fabric according to any one
of claims 1 to 11.
13. The car airbag of claim 12, which is a side curtain type of airbag
for vehicles. |
INFLATABLE TWO-LAYER FABRICS BY GAS
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to an inflatable fabric that can be
inflated with air, and more particularly to an inflatable fabric that can be used
for car airbags, life jackets, and so forth.
(b) Description of the Related Art
An inflatable fabric can be used for car airbags, life jackets, and the
like. The inflatable fabric is especially useful for a side curtain type of
airbag which is unfolded at the side windowpane to protect an occupant's
head from being hurt by collision with the windowpane or other structures
when a car overturns in an accident. For the airbag to safely protect the
occupant, it should be at an inflated state for at least 5 seconds when the
car rolls over, and the inflatable fabric is useful for this purpose.
In general, methods for manufacturing inflatable fabrics for car
airbags are classified into: 1) a method of sewing, sewing, fusing, or
adhering two fabrics; and 2) a method of using a two-layer fabric wherein
the two layers of the fabric are partly joined by an attachment area.
However, the first method for preparing the inflatable fabric by
sewing, fusing with heat or microwave treatment, or adhering the two fabrics i
with adhesive requires additional sewing, fusing, or adhering procedures
following manufacturing of the two fabrics after preparation of the textile
fabric consisting of the two layers, resulting in complicated procedures and
increasing manufacturing costs.
To solve this problem, the second method for preparing the
inflatable products such as the airbag with the two inflatable layers has been
furthered recently.
An inflatable fabric that is inflated by air or another gas has two
separate fabric layers and an attachment area between the layers. The
fabric enclosed by such an attachment area strongly interlocks the two
layers when each individual layer rapidly inflates, so that air or a gas does
not leak out.
Methods for forming an attachment area in the inflatable fabric have
been proposed by USP Nos. 6,220,309, 5,098,125, 5,011 ,183, 5,603,647
and 6,595,244.
USP No. 6,220,309 discloses a fabric whose separator area is
formed in a plain weave and whose attachment area is formed in a 2/2
basket weave. USP No. 5,098,125 and USP No. 5,011 ,183 disclose a two-
layer fabric whose separator area is formed in a plain weave and whose
attachment area is formed in (a 2/2 basket or 3/3 basket weave) + (a 1/2
twill or 1/3 twill wave) + (a 5 harness satin). USP No. 5,603,647 discloses
a two-layer fabric whose separator area is formed in a plain weave, a basket
weave or a twill weave and whose attachment area is formed in a 3/3
basket weave. Here, the separator area refers to the area in the fabric
where the two fabric layers (upper and lower layers) are separated from
each other, so that the fabric may inflate by air, etc. In addition, the
attachment area refers to the area where the two separated fabric layers are
attached to each other.
The above-mentioned two-layer fabrics mainly utilize attachment
areas formed in a 3/3 basket weave or a 2/2 basket weave. However, if
they are used alone, air or gas may leak out at the attachment area,
resulting in a high breathability property when the two separated layers
inflate.
USP No. 6,595,244 discloses a fabric whose attachment point
comprises at most a 12 yarn basket weave. However, the attachment
point is not strong enough because the single fabric layer (basket weave) is
formed solely from one type of yarn. If the middle of the two-layer fabric is
changed into a basket pattern in order to increase strength, tension applied
to the yarns at the attachment point becomes too high due to the whole
attachment point consisting of the basket weave, so that weaving becomes
very difficult and the shape and performance of the fabric may be negatively
affected.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems described
above and to provide an inflatable fabric with an attachment area that is
dense and hard such that air leakage at the attachment area can be
minimized when the fabric is inflated because of remarkably lowering a
breathability property of the attachment area.
Another object of the present invention is to provide an inflatable
fabric having all fabric layers formed in a plain weave so that air bags with a
variety of forms can be made utilizing jacquard, that is capable of being
produced without a sewing process so that manufacture cost can be
lowered significantly, and that has good weaving properties and
smoothness.
Still another object of the present invention is to provide a car airbag
comprising said inflatable fabric.
In order to attain the objects, the present invention provides an
inflatable fabric comprising at least a separate area of two separated fabric
layers which are woven at the same time using a weaving machine, and at
least one attachment area where a single layer of fabric is formed, wherein
said attachment area is formed from at least a weave pattern of at least 13
yarns selected from the group consisting of a 2/2 basket weave pattern, a
satin weave pattern, a partial attaching weave of a double layer weave
pattern, a plain weave pattern, and a combination thereof.
Said inflatable fabric comprises the separator area (A, B) consisting
of two separated fabric layers and an attachment area (C) where a single
layer of fabric is formed together.
Said separator area (A, B) is consiting of two separated fabric layers
with a plain weave pattern. The left seperator area (A) and the right
separator area (B) of said separator area (A, B)located at the left and right
sides of said attachment area, respectively, have an the same weave
pattern. Preferably, said attachment area (C) is formed from at least a
pattern of 13 to 50 yarns selected from the group consisting of a 2/2 basket
weave pattern, a satin weave pattern, a partial attaching weave of a double
layer weave pattern, a plain weave pattern, and a combination thereof.
Also preferably, said inflatable fabric is coated with a synthetic resin.
The present invention also provides a car airbag prepared by
comprising said inflatable fabric. Preferably, said airbag is a side curtain
type of airbag for protecting occupants of a car.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows weave diagrams illustrating the weave pattern (a) of
the inflatable fabric of the present invention having two separated plain
weave planes and an extended pattern (b) thereof.
FIG. 2 is a cross-sectional view of the inflatable fabric of the present
invention.
FIG. 3 is a cross-sectional view of the inflatable fabric of the present
invention that has been inflated by air.
FIG. 4 shows a cross-section and a weave pattern of a 2/2 basket
weave pattern (a), a cross-section and a weave pattern of a plain partial
double weave pattern (b), and a cross-section and a weave pattern of a
satin weave pattern (c) at the attachment area of the separated inflatable
fabric.
FIG. 5 shows a method of measuring the pressure inside an airbag.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, the present invention is described in more detail.
The present invention relates to an inflatable fabric that is capable of
simplifying a manufacturing process of shock-absorbing products such as
an airbag and lowering a cost thereof, that is capable of minimizing air
leakage at an attachment area during inflation of a separator area, and that
has a superior weaving property and surface smoothness and is capable of
being easily coated with a synthetic resin.
The present invention is characterized in that strength, weaving
property, and folding property of the attachment area of the inflatable fabric
are improved, as the attachment area comprises at least 13 yarns.
Thus, the inflatable fabric of the present invention comprises at least
a separate area of two separated fabric layers which are woven at the same
time using a weaving machine, and at least one attachment area where a
single layer of fabric is formed, wherein said attachment area is formed from
at least a weave pattern of at least 13 yarns selected from the group
consisting of a 2/2 basket weave pattern, a satin weave pattern, a partial
attaching weave of a double layer weave pattern, a plain weave pattern, and
a combination thereof.
More preferably, the attachment area is formed from a combination
weave patterns comprising at least two weave pattern selected from the
group consisting of a 2/2 basket weave pattern, a satin weave pattern, a
partial attaching weave of a double layer weave pattern, and a plain
weave pattern of at least 13 yarns. Most preferably, the attachment area is
formed from a combination weave pattern of at least 13 yarns comprising a
partial attaching weave of a double layer weave pattern in the middle of the
attachment area and at least one weave pattern selected from a 2/2 basket
weave pattern, a satin weave pattern, and a plain weave pattern on either
side of the middle part, and the attachment area.
Reference will now be made in detail to the embodiments of the
present invention, examples of which are illustrated in the accompanying
drawings.
FIG. 1 shows weave diagrams illustrating the weave pattern (a) of
the inflatable fabric of the present invention having two separated plain
weave planes and an extended pattern (b) thereof. FIG. 2 is a cross-
sectional view of the inflatable fabric of the present invention.As seen in FIG.
2, the inflatable fabric of the present invention comprises a separator area
(A, B) consisting of two separated fabric layers with a plain weave pattern
and an attachment area (C) where a single layer of fabric is formed. The
two separated fabric layers (A and B in FIG. 2 and FIG. 3) are
simultaneously woven into a plain weave pattern using a jacquard weaving
machine, and the attachment area (C) attaching the two fabric layers is
woven into a weave pattern selected from the group consisting of a 2/2
basket weave pattern (FIG. 4a), a satin weave pattern (FIG. 4c), a partial
attaching weave of a double layer weave pattern (FIG. 4b), a plain weave
pattern, and a combination thereof. The attachment area is formed from at
least 13 yarns, preferably 13 to 50, yarns. That is, the total number of
yarns of the attachment area is at least 13. The main object of the fabric
layer of the present invention is to be inflated by air or gas. The
attachment area prevents the gas from leaking out of the two separated
fabric layers, while withstanding the pressure of the expanding gas.
In the present invention, the attachment area (C) refers to a point,
line, or plane in the two separated fabric layers of the separator area (A, B)
where the warp of the upper layer and the weft of the lower layer form a
weaving point, the weft of the upper layer and the warp of the lower layer
form a weaving point, the warp of the lower layer and the weft of the upper
layer form a weaving point, or the weft of the lower layer and the warp of the
upper layer form a weaving point, so that the two fabric layers make a single
layer. Such a structure having an attachment is called an attachment
structure. When an attachment structure is formed as a point, it is called
an attachment point; when an attachment structure is formed as a line, it is
called an attachment line; and when an attachment structure is formed as a
plane, it is called an attachment plane. The attachment point, attachment
line, and attachment plane are collectively called an attachment area. The
weaving point refers to an area where the warp and the weft cross each
other, so that a fabric can be formed.
A fabric having a structure separated into an upper layer and a lower
layer and an attachment structure can be divided into a separator area (A
and B of FIG. 2 and FIG. 4) and an attachment area (C of FIG. 2 and FIG.
4). Also, it can be divided into the following three areas: an area enclosed
by the separator structure (B of FIG. 4), or an inflating area; an attachment
area (C of FIG. 2 and FIG. 4); and an area outside the area enclosed by the
attachment structure (A FIG. 4), which is irrelevant with respect to inflation.
In FIG. 2, the left separator area (A) is located at the left side of the
attachment area and the separator area (B) is located at the right side of the
attachment area. The left and right separator areas are separated by the
attachment area comprising at least 13 yarns. The structure of the
attachment area is shown in FIG. 4. Preferably, the attachment area is
formed from a weave pattern selected from the group consisting of a 2/2
basket weave pattern (FIG. 4a), a satin weave pattern (FIG. 4c), a partial
double weave pattern (FIG. 4b), a plain weave pattern, and a combination
thereof.
In the present invention, the attachment area refers to the whole of
the area (C) (a single layer). The whole of this attachment area comprises
at least 13 yarns. Also, in the present invention, the whole of the
attachment area (C) is not a two-layer fabric of a single pattern (for example,
a basket weave), but is formed from a combination weave pattern
comprising at least two weave pattern selected from the group consisting of
a 2/2 basket weave pattern, a satin weave pattern, and a partial double
weave pattern. Preferably, at least one weave pattern selected from a 2/2
basket weave pattern and a satin weave pattern is located on either side of
a partial double weave, with the attachment area comprising at least 13
yarns. As at least 13 yarns are weaved into at least two weave pattern
selected from the group consisting of a 2/2 basket weave pattern, a satin
weave pattern and a partial double weave pattern to form the attachment
area (c), the attachment area has enhanced strength since the pulling effect
during weaving can be reduced and such problems as reduction of weaving
property, deformation, and reduction of performance can be prevented.
As mentioned above, as the attachment area comprises at least 13
yarns, a dense and hard the attachment area becomes very strong during
inflation and effectively prevents air from leaking out when the fabric is
inflated.
In addition, since the attachment area is formed from a combination
comprising at least two weave pattern selected from the group consisting of
a basket weave pattern, a satin weave pattern, and a partial double weave
pattern rather than a single pattern, it has an improved weaving property
and folding property.
Also, preferably, the inflatable fabric of the present invention is
coated with a synthetic resin to reduce air leakage.
For said synthetic resin, any synthetic resin commonly used in fabric
coating can be used. Preferably, a silicone resin coating is suitable in view
of airtightness and strength.
The silicone resin coating is carried out to effectively fill up small
spaces of the two-layer fabric. It may be performed on either side or on
both sides of the fabric. For the coating method, multi-step coating is
preferred. If undercoating and top coating are carried out as the multi-step
coating, airtightness can be improved and the fabric becomes more flexible
because the fabric does not need to be thick.
Preferably, the synthetic resin is coated in the range from 40 g/m 2 to
150 g/m 2 . If the coating amount is less than 40 g/m 2 , a lot of air leaks out
of the airbag, and therefore the inflated state cannot be maintained for over
5 seconds. Otherwise, if the coating amount exceeds 150 g/m 2 , the airbag
becomes too thick and it may contact other structures during inflation.
In the inflatable fabric of the present invention, the separator area
has a double structure of upper and lower layers formed by a plain weave
(FIG. 1), and the attachment area comprises at least 13 to 50 yarns. A
inflatable fabric having such a structure can prevent leakage of air or
another gas, when inflated.
To ensure airtightness of the inflatable fabric, it is very important to
minimize extension of the fabric by offering enough tensile resistance
against high-pressure air, etc. Therefore, the structure at the part where
the two layers begin to separate from each other, or where the attachment
begins, is a very important factor in designing an inflatable fabric.
In the inflatable fabric of the present invention, this problem is solved
by using a plain weave pattern, which offers high resistance against external
tension, in the fabric layer. Preferably, a high-density fabric having a cover
factor defined by the following Equation 1 of over 1900 is used to offer good
airtightness to the airbag. If the cover factor is below 1900, air tends to
leak out during inflation.
Equation 1
Cover factor (CF) = warp density (number/inch) * SQRT (warp denier) +
weft density (number /inch) x SQRT (weft denier)
Also, preferably, the inflatable fabric of the present invention has an
air leakage per unit length (measured at 2.5 kPa) at the attachment area of
less than 0.8 i /min ■ cm. If the air leakage per unit length at the attachment
area exceeds 0.8 £ /mirvcm, the car airbag made of the fabric cannot
protect occupants effectively.
Further, preferably, each single fabric layer of the two-layer fabrics in
the separate area of the present invention has a thickness measured by the
ASTM D 1777 method of less than 0.5 mm and a stiffness value measured
by the ASTM D 4032 circular band method of less than 3.5 kgf. If the
thickness of each fabric layer exceeds 0.5 mm, it is not easy to set up the
car airbag inside a vehicle. Also, if the stiffness exceeds 3.5 kgf, the car
airbag may not inflate normally by the air pressure.
When an initial pressure of 50 kPa has been applied to the airbag,
the inner pressure of the airbag should be at least 6 kPa after 5 seconds for
it to normally function as a side curtain type airbag. Also, when the side
curtain type of airbag inflates under high temperature and high pressure, the
seam strength of the attachment area (C of FIG. 2) measured by the ASTM
D 5822 method should be at least 80 kg/in to prevent tearing of the airbag.
Further, in order to minimize air leakage at the attachment area during
inflation and to prevent melting of the fabric by heat, the breaking modulus
should not exceed 60%. Particularly, because a side curtain type of airbag
requires a relatively higher coating amount than other airbags, it should be
able to maintain its strength for a long time even after the fabric has been
worn by vibration of the car. To satisfy these requirements, the inflatable
fabric of the present invention has an inner pressure of at least 6 kPa after 5
seconds when gas having an initial pressure of 50 kPa has been applied, a
seam strength of at least 80 kg/in at the attachment area, a breaking
modulus of less than 60%, and a strength maintenance ratio measured by
the ASTM D 4157 method of at least 80%. If the strength maintenance
ratio is less than 80%, the airbag may be torn during inflation.
The present invention further provides a side curtain type of airbag
for vehicles comprising said inflatable fabric. The side curtain type of
airbag of the present invention remains inflated for at least 5 seconds while
the vehicle is rolling over. For the side curtain type of airbag to function
normally, the pressure inside the airbag should be at least 50 kPa.
As described above, the inflatable fabric of the present invention,
which has a strong attachment area, minimizes air leakage during inflation,
and thus it is useful for car airbags, life jackets, and other shock-absorbing
products. In addition, since the attachment area of the inflatable fabric of
the present invention is formed from a combination weave pattern
comprising at least two weave pattern selected from the group consisting of
a basket weave pattern, a satin weave pattern, and a partial attaching
weave of a double layer weave pattern, it has an improved weaving property
and folding property. Further, since the inflatable fabric of the present
invention requires no sewing, the manufacture process can be simplified
and thus manufacture cost can be reduced.
Hereinafter, the present invention is described in more details
through examples. However, the following examples are only for the
understanding of the present invention and they are not to be construed as
limiting the scope of the present invention.
EXAMPLES
Physical properties of the inflatable fabric of the present invention
were measured as follows.
a) Pressure inside airbag:
Referring to FIG. 5, pressure inside the airbag increases as air is fed
in. The feed of air was stopped when the pressure reached its maximum
and the change of the pressure inside the airbag was observed for 5.0
seconds. To minimize errors, feeding and stopping of air were controlled
with an electronic controller.
b) Air leakage per unit length ( i /min • cm) at attachment area:
Air leakage was measured with a measuring device equipped with
an air pressure regulator, an air flow meter, and a pressure gauge. Air
pressurized to 2.5 kPa was injected into the separator area of the two-layer
fabric, so that the inflatable fabric inflated completely. Then, the volume of
air (unit: i ) leaking out of the inflatable fabric per unit time (1 minute) was
measured and divided into the total attachment length (unit: cm) measured
with a vernier caliper, a measuring tape, or a ruler to obtain the air leakage
per unit length at the attachment area.
c) Cover factor: Calculated by the following Equation 1.
Equation 1
Cover factor (CF) = warp density (number /inch) * SQRT (warp denier) +
weft density (number /inch) * SQRT (weft denier)
d) Stiffness: Measured by the ASTM D 4032 circular bend method.
e) Thickness of single fabric layer: Measured by the ASTM D 1777
method.
f) Seam strength: Measured by the ASTM D 5822 method.
g) Strength maintenance ratio: Measured by the ASTM D 4157
method.
Example 1
A inflatable fabric, the left separator area (A) and the right separator
area (B) of which having the structure shown in FIG. 1 and FIG. 2 and being
separated by the attachment area (C) which comprised 20 yarns and was
formed from a combination weave pattern of a 2/2 basket weave pattern
and a partial attaching weave of plain double weave pattern, was prepared
with a jacquard weaving machine using 426-denier polyamide multifilament
as warp and weft. Both the warp density and the weft density were 52
number /inch, and the cover factor was 2,131. Then, silicone rubber was
coated on both sides of the inflatable fabric by a two-step coating process
(coating amount: 100 g/cm 2 ). The fabric was cut and air leakage per unit
length at the attachment area, thickness of a single fabric layer, and
stiffness were measured. The air leakage per unit length at the attachment
area was 0.6 £ /min cm, the stiffness was 2.5 kgf, and the thickness of a
single fabric layer was 0.4 mm.
Example 2
A inflatable fabric, the left separator area (A) and the right separator
area (B) of which having the structure shown in FIG. 1 and FIG. 2 and being
separated by the attachment area (C) which comprised 20 yarns and was
formed from a combination weave pattern of a 2/2 basket weave pattern
and a partial attaching weave of a double layer weave pattern, was
prepared with a jacquard weaving machine using 315-denier polyamide
multifilament as warp and weft. Both the warp density and the weft density
were 60 number /inch, and the cover factor was 2,129. Then, silicone
rubber was coated on both sides of the inflatable fabric by a two-step
coating process of undercoating and top coating (coating amount: 100
g/cm 2 ) in order to prevent air leakage at the attachment area. The fabric
was cut and air leakage per unit length at the attachment area, thickness of
a single fabric layer, and stiffness were measured. The air leakage per unit
length at the attachment area was 0.7 i /min cm, the stiffness was 1.9 kgf,
and the thickness of a single fabric layer was 0.39 mm.
Example 3
A inflatable fabric was prepared in the same manner as in Example
2, except that the coating amount of silicone rubber was changed to 90 g/m 2 .
The thickness of a single layer of the inflatable fabric measured by
the ASTM D 1777 method was 0.39 mm and the stiffness value measured
by the ASTM D 4032 circular band method was 1.9 kgf. An initial pressure
of 50 kPa was applied to an airbag comprising the fabric, and the inner
pressure of the airbag was measured 5 seconds later at 12.5 kPa. The
seam strength of the attachment area (C of FIG. 2) measured by the ASTM
D 5822 method was 119 kg/in and the breaking modulus was 43%. Also,
the strength maintenance ratio measured by the coating fabric wear test
according to the ASTM D 4157 method was 90%. To conclude, the fabric
had good installation characteristics and inflatability for use as a side curtain
type of airbag.
Example 4
A inflatable fabric was prepared in the same manner as in Example
1 , except that the attachment (C) area was formed in a basket weave and a
satin weave using 20 yarns.
The thickness of a single layer of the inflatable fabric measured by
the ASTM D 1777 method was 0.4 mm, and the stiffness value measured
by the ASTM D 4032 circular band method was 2.5 kgf. An initial pressure
of 50 kPa was applied to an airbag comprising the fabric, and the inner
pressure of the airbag was measured 5 seconds later at 9.5 kPa. The
seam strength of the attachment area (C of FIG. 2) measured by the ASTM
D 5822 method was 123 kg/in and the breaking modulus was 49%. Also,
the strength maintenance ratio measured by the coating fabric wear test
according to the ASTM D 4157 method was 93%. To conclude, the fabric
had good installation characteristics and inflatability for use as a side curtain
type of airbag.
Comparative Example 1
A inflatable fabric, whose attachment area was formed from a 2/2
basket weave and whose separator area was formed from a plain weave
pattern, was prepared with a jacquard weaving machine using 426-denier
polyamide multifilament as warp and weft. Both the warp density and the
weft density were 53 number /inch. Then, silicone rubber was coated on
both sides of the inflatable fabric by a two-step coating process (coating
amount: 100 g/cm 2 ). The fabric was cut and air leakage per unit length at
the attachment area, thickness of a single fabric layer, and stiffness were
measured. The air leakage per unit length at the attachment area was
0.9 i /min cm, the stiffness was 3.6 kgf, and the thickness of a single fabric
layer was 0.52 mm. In case of use for a car airbag, air leakage was too high
to effectively protect occupants.
Comparative Example 2
A inflatable fabric was prepared in the same manner as in Example
4, except that both the warp density and the weft density were changed to
46 number /inch and the cover factor of textile fabric for one plane was 1880.
The prepared fabric was coated in the same manner as in Example
1. The thickness of a single fabric layer measured by the ASTM D 1777
method and the stiffness value measured by the ASTM D 4032 circular
band method were favorable, being 0.38 mm and 1.9 kgf, respectively. An
initial pressure of 50 kPa was applied to an airbag comprising the fabric and
the inner pressure of the airbag was measured 5 seconds later at 5.8 kPa.
The seam strength of the attachment area (C of FIG. 2) measured by the
ASTM D 5822 method was 109 kg/in, and the breaking modulus was 47%.
Also, the strength maintenance ratio measured by the coating fabric wear
test according to the ASTM D 4157 method was 90%, resulting in good
installation characteristics. However, the inner pressure was too low,
indicating that a lot of air leaked out of the airbag and that the airbag could
not normally protect occupants.
Comparative Example 3
A inflatable fabric prepared in the same manner as in Example 1
was coated by a single coating process, with a coating amount of 200 g/m 2 .
Air leakage per unit length of the fabric when measured at a pressure of 2.5
kPa was favorable, at 0.6 £ /min • cm. However, the thickness of the fabric
measured by the ASTM D 1777 was 0.52 mm and the stiffness value
measured by the ASTM D 4032 circular band method was 3.6 kgf, indicating
that the fabric is disadvantageous in terms of installation characteristics and
inflatability, when used for a side curtain type of airbag.
As apparent from the above description, because the attachment
area of the inflatable fabric of the present invention is formed from at least a
weave pattern of at least 13 yarns selected from the group consisting of a
2/2 basket weave pattern, a satin weave pattern, a partial attaching weave
of a double layer weave pattern, a plain weave pattern, and a combination
thereof, the attachment area maintains superior strength during inflation,
and thus it minimizes air leakage. Also, since the attachment area is
formed from a combination comprising at least two weave pattern selected
from the group consisting of a basket weave pattern, a satin weave pattern,
and a partial double weave pattern, rather than a single weave pattern, it
has an improved weaving property and folding property.
Also, since a sewing process can be omitted, the present invention
can reduce manufacture cost of shock-absorbing products including airbags.
With a superior weaving property and surface smoothness, the fabric of the
present invention can be utilized for car airbags, life jackets, and other
shock-absorbing products when coated with synthetic resins.
While the present invention has been described in detail with
reference to the preferred embodiments, those skilled in the art will
appreciate that various modifications and substitutions can be made thereto
without departing from the spirit and scope of the present invention as set
forth in the appended claims.