U.S. patent application number 14/432047 was filed with the patent office on 2015-09-10 for sound-absorbing material with excellent sound-absorbing performance and method for manufacturing thereof.
This patent application is currently assigned to Hyundai Motor Company. The applicant listed for this patent is WOONGJIN CHEMICAL CO., LTD.. Invention is credited to Kie Youn Jeong, Chi Hun Kim, Do Hyun Kim, Hyo Seok Kim, Jung Wook Lee, Bong Hyun Park.
Application Number | 20150252562 14/432047 |
Document ID | / |
Family ID | 48997932 |
Filed Date | 2015-09-10 |
United States Patent
Application |
20150252562 |
Kind Code |
A1 |
Kim; Hyo Seok ; et
al. |
September 10, 2015 |
SOUND-ABSORBING MATERIAL WITH EXCELLENT SOUND-ABSORBING PERFORMANCE
AND METHOD FOR MANUFACTURING THEREOF
Abstract
The present invention provides a sound-absorbing material with
excellent sound-absorbing performance and a method for
manufacturing thereof. More particularly, it relates to a
sound-absorbing material, which can improve sound absorption
coefficient and transmission loss by forming large surface area and
air layer, so as to induce viscosity loss of incident sound energy,
may make light-weight design possible because it can express
excellent sound-absorbing performance even using reduced amount of
fiber, and can improve sound-absorbing performance by using binder
fiber having rebound resilience, so as to maintain enough strength
between fiber and also to maximize viscosity loss of sound energy
transmitted to fiber structure; and a method for manufacturing
thereof.
Inventors: |
Kim; Hyo Seok; (Namyangju,
KR) ; Kim; Do Hyun; (Hwaseong, KR) ; Kim; Chi
Hun; (Yongin, KR) ; Jeong; Kie Youn;
(Hwaseong, KR) ; Park; Bong Hyun; (Gunpo, KR)
; Lee; Jung Wook; (Bucheon, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WOONGJIN CHEMICAL CO., LTD. |
Gyeongsangbuk-do |
|
KR |
|
|
Assignee: |
Hyundai Motor Company
Seoul
KR
|
Family ID: |
48997932 |
Appl. No.: |
14/432047 |
Filed: |
September 26, 2013 |
PCT Filed: |
September 26, 2013 |
PCT NO: |
PCT/KR2013/008630 |
371 Date: |
March 27, 2015 |
Current U.S.
Class: |
181/294 ;
252/62 |
Current CPC
Class: |
E04B 1/84 20130101; D04H
1/542 20130101; G10K 11/162 20130101; D01D 5/253 20130101; D04H
1/4391 20130101; D04H 1/541 20130101; D04H 1/485 20130101 |
International
Class: |
E04B 1/84 20060101
E04B001/84 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2012 |
KR |
10-2012-0108764 |
Claims
1. A method for manufacturing a sound-absorbing material,
comprising forming a fiber aggregate in a nonwoven fabric form,
wherein the fiber aggregate comprises: a non-circular shaped fiber
satisfying the following Formula 1; and a binder fiber that partly
binds a plurality of the non-circular shaped fibers, 1.5 .ltoreq. P
4 .times. .pi. .times. A Formula 1 ##EQU00007## wherein A is a
fiber cross sectional area (.mu.m.sup.2), P is a circumference
length of fiber cross section (.mu.m).
2. The method for manufacturing a sound-absorbing material of claim
1, wherein the sound-absorbing material is manufactured by using
the non-circular shaped fiber satisfying the value of the Formula 1
of 2.6 or greater.
3. The method for manufacturing a sound-absorbing material of claim
1, wherein the non-circular shaped fiber is at least one selected
from the group consisting of six-pointed star shape, 3-bar flat
type, 6-leaf type, 8-leaf type and wave type.
4. The method for manufacturing a sound-absorbing material of claim
1, wherein the non-circular shaped fiber is 35 to 65 mm in
length.
5. The method for manufacturing a sound-absorbing material of claim
1, wherein the binder fiber comprises a low melting (LM) elastomer
having elastic recovery modulus of 50 to 80%.
6. The method for manufacturing a sound-absorbing material of claim
5, wherein the binder fiber is a conjugated fiber which is
conjugate-spun by using the LM elastomer as one component.
7. The method for manufacturing a sound-absorbing material of claim
5, wherein the LM elastomer is at least one selected from the group
consisting of a polyester-based polymer, a polyamide-based polymer,
a polystyrene-based polymer, a polyvinylchloride-based polymer and
a polyurethane-based polymer.
8. The method for manufacturing a sound-absorbing material of claim
5, wherein the LM elastomer is manufactured by esterification and
polymerization steps using dimethyl terephthalate(DMT) and dimethyl
isophthalate(DMI) or terephthalic acid(TPA) and isophthalic
acid(IPA) as an acid ingredient(Diacid), and
1,4-butanediol(1,4-BD), polytetramethyleneglycol(PTMG) as a diol
ingredient (Diol).
9. The method for manufacturing a sound-absorbing material of claim
1, wherein the sound-absorbing material is manufactured by using
the non-circular shaped fiber of 50 to 80 wt % based on the total
weight of the sound-absorbing material and the binder fiber of 20
to 50 wt % based on the total weight of the sound-absorbing
material.
10. The method for manufacturing a sound-absorbing material of
claim 1, wherein the non-circular shaped fiber satisfies the value
of the Formula 1 of 3.0 or greater.
11. A sound-absorbing material, comprising: a non-circular shaped
fiber satisfying the following Formula 1; and a binder fiber that
partly binds a plurality of the non-circular shaped fibers, 1.5
.ltoreq. P 4 .times. .pi. .times. A Formula 1 ##EQU00008## wherein
A is a Fiber cross sectional area (.mu.m.sup.2),), P is a
Circumference length of fiber cross section (.mu.m).
12. The sound-absorbing material of claim 11, wherein the
non-circular shaped fiber satisfies the value of the Formula 1 of
2.6 or greater.
13. The sound-absorbing material of claim 11, wherein the
non-circular shaped fiber is at least one selected from the group
consisting of six-pointed star shape, 3-bar flat type, 6-leaf type,
8-leaf type and wave type.
14. The sound-absorbing material of claim 11, wherein the
non-circular shaped fiber is 35 to 65 mm in length.
15. The sound-absorbing material of claim 11, wherein the
non-circular shaped fiber is 1.0 to 7.0 De in fineness.
16. The sound-absorbing material of claim 11, wherein the binder
fiber comprises a low melting (LM) elastomer having elastic
recovery modulus of 50 to 80%.
17. The sound-absorbing material of claim 16, wherein the binder
fiber is conjugated fiber which is conjugate-spun by using the LM
elastomer as one component.
18. The sound-absorbing material of claim 16, wherein the LM
elastomer is at least one selected from the group consisting of a
polyester-based polymer, a polyamide-based polymer and a
polyurethane-based polymer.
19. The sound-absorbing material of claim 11, which comprises the
non-circular shaped fiber of 50 to 80 wt % based on the total
weight of the sound-absorbing material and the binder fiber of 20
to 50 wt % based on the total weight of the sound-absorbing
material.
20. The sound-absorbing material of claim 11, wherein the
non-circular shaped fiber satisfies the value of the Formula 1 of
3.0 or greater.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a National Phase application filed under
35 USC 371 of PCT International Application PCT/KR13/008630 filed
Sep. 26, 2013, which claims the benefit of Korean Patent
Application No. 10-2012-0108764 filed on Sep. 28, 2012, the entire
contents of which are incorporated herein by reference.
BACKGROUND
[0002] (a) Technical Field
[0003] The present invention relates to a sound-absorbing material
with excellent sound-absorbing performance and a method for
manufacturing the same. More particularly, it relates to a
sound-absorbing material with excellent sound-absorbing
performance, which can be used for blocking inflow of external
noise into vehicle interior by being attached as vehicle components
or interior and exterior materials of a vehicle body, and can be
used in electric devices and the like that use motor parts so as to
improve noise insulation performance thereof
[0004] (b) Background Art
[0005] In general, noise introduced into a vehicle may be
classified into a noise generated at an engine and introduced
through a vehicle body and a noise generated when tires are
contacted with a road surface and introduced through a vehicle
body. There may be two ways to block theses noises such as
improving sound-absorbing performance and improving noise
insulation performance. Sound-absorbing means that generated sound
energy is converted into thermal energy and then dissipated while
it is transmitted through internal route of a material, and noise
insulation means that generated sound energy is reflected and
blocked by a shelter.
[0006] According to such characteristics of sound, in order to
improve Noise, Vibration & Harshness (NVH) of a vehicle in
general, a heavier and thicker sound-absorbing material has been
mainly used in luxury cars. However, when such sound-absorbing
material is used, noise may be reduced, but there is a problem of
deteriorating fuel efficiency by increasing vehicle weight.
[0007] Further, in order to overcome problems of the conventional
sound-absorbing material, a method in which porosity of the
material is improved by thinning fiber thickness have been
developed thereby improving sound-absorbing performance and also
reducing weight of fiber aggregate. However, this method may also
have a weakness such that needs surface density of the fiber
aggregate may be improved in order to improve the desired NVH
performance.
[0008] Further, in order to manufacture non-woven type fiber
aggregate, staple fiber and binder fiber are mixed together at a
proper ratio. As the binder fiber, in general, staple fiber
manufactured by conjugate-spinning regular polyester is used for an
inner layer and low melting polyester is used for an outer
layer.
[0009] However, when using this conventional binder fiber with the
low melting polyester, the fiber aggregate is hardened, and thus
there may be a problem that vibration generated by sound wave
propagation and transmitted to matrix structure is not fully
attenuated, thereby reducing sound absorption coefficient mainly at
low frequency region.
SUMMARY OF THE INVENTION
[0010] The present invention has been made in an effort to solve
the above-described problems associated with prior art.
[0011] The present invention is objected to provide a
sound-absorbing material, which may improve sound absorption
coefficient and transmission loss by forming large surface area and
air layer, so as to maximize viscosity loss and dissipation route
of incident sound energy, and makes light-weight design thereof
possible because it can realize excellent sound-absorbing
performance even using reduced amount of fiber; and a method for
manufacturing thereof
[0012] Further, the present invention is objected to provide a
sound-absorbing material, which may improve formability as well as
maintain enough strength between fiber, and may have improved
rebound resilience, thereby ultimately having excellent vibration
attenuation capability against sound energy transmitted inside
matrix; and a method for manufacturing thereof
[0013] To achieve the above objects, in one aspect, the present
invention provides a method for manufacturing a sound-absorbing
material that comprises forming fiber aggregate in a nonwoven
fabric form, and the fiber aggregate comprises:
[0014] a non-circular shaped fiber satisfying the following Formula
1; and
[0015] a binder fiber that partly binds a plurality of the
non-circular shaped fibers.
1.5 .ltoreq. P 4 .times. .pi. .times. A Formula 1 ##EQU00001##
[0016] (A: Fiber cross sectional area (.mu.m.sup.2), P:
Circumference length of fiber cross section (.mu.m))
[0017] In a preferred embodiment, the sound-absorbing material may
be manufactured by using the non-circular shaped fiber satisfying
the value of the Formula 1 of 2.6 or greater.
[0018] In another preferred embodiment, the sound-absorbing
material may be manufactured by using the non-circular shaped fiber
satisfying the value of the Formula 1 of 3.0 or greater.
[0019] In still another preferred embodiment, the non-circular
shaped fiber may be at least one selected from the group consisting
of six-pointed star shape, 3-bar flat type, 6 leaf type, 8 leaf
type and wave type.
[0020] In yet another preferred embodiment, the non-circular shaped
fiber may be 35 to 65 mm in length.
[0021] In still yet another preferred embodiment, the binder fiber
may comprise a low melting (LM) elastomer having elastic recovery
modulus of 50 to 80%, and rebound resilience rate of the
sound-absorbing material may be 50 to 80%.
[0022] In a further preferred embodiment, the binder fiber may be
conjugated fiber which is conjugate-spun by using the LM elastomer
as one component.
[0023] In another further preferred embodiment, the LM elastomer
may be at least one selected from the group consisting of a
polyester-based polymer, a polyamide-based polymer, a
polystyrene-based polymer, a polyvinylchloride-based polymer and a
polyurethane-based polymer.
[0024] In still another further preferred embodiment, the LM
elastomer may be manufactured by esterification and polymerization
steps using dimethyl terephthalate(DMT) and dimethyl
isophthalate(DMI), or terephthalic acid(TPA) and isophthalic
acid(IPA) as an acid ingredient(Diacid), and 1,4-butanediol(1,4-BD)
and polytetramethyleneglycol(PTMG) as a diol ingredient (Diol).
[0025] In yet another further preferred embodiment, the
sound-absorbing material may be manufactured by using the
non-circular shaped fiber of 50 to 80 wt % based on the total
weight of the sound-absorbing material and the binder fiber of 20
to 50 wt % based on the total weight of the sound-absorbing
material.
[0026] Further, in another aspect, the present invention provides a
sound-absorbing material, which may comprise: a non-circular shaped
fiber satisfying the following Formula 1; and a binder fiber which
partly binds a plurality of the non-circular shaped fibers.
1.5 .ltoreq. P 4 .times. .pi. .times. A Formula 1 ##EQU00002##
[0027] (A: Fiber cross sectional area (.mu.m.sup.2), P:
Circumference length of fiber cross section (.mu.m))
[0028] In a preferred embodiment, the non-circular shaped fiber may
satisfy the value of the Formula 1 of 2.6 or greater.
[0029] In another preferred embodiment, the non-circular shaped
fiber may be at least one selected from the group consisting of
six-pointed star shape, 3-bar flat type, 6-leaf type, 8-leaf type
and wave type.
[0030] In still another preferred embodiment, the non-circular
shaped fiber may be 35 to 65 mm in length.
[0031] In yet another preferred embodiment, the non-circular shaped
fiber may be 1.0 to 7.0 De in fineness.
[0032] In still yet another preferred embodiment, the binder fiber
may comprise a LM elastomer having elastic recovery modulus of 50
to 80%, and rebound resilience rate of the sound-absorbing material
may be 50 to 80%.
[0033] In a further preferred embodiment, the binder fiber may be
conjugated fiber which is conjugate-spun by using the LM elastomer
as one component.
[0034] In another further preferred embodiment, the LM elastomer
may be at least one selected from the group consisting of a
polyester-based polymer, a polyamide-based, polystyrene-based
polymer, a polyvinylchloride-based polymer and a polyurethane-based
polymer.
[0035] In still another further preferred embodiment, the
sound-absorbing material may comprise the non-circular shaped fiber
of 50 to 80 wt % based on the total weight of the sound-absorbing
material and the binder fiber of 20 to 50 wt % based on the total
weight of the sound-absorbing material.
[0036] In yet another further preferred embodiment, the
non-circular shaped fiber may satisfy the value of the Formula 1 of
3.0 or greater.
[0037] Hereinafter, terms used in the present invention will be
described.
[0038] The term "wave type non-circular shaped fiber", as used in
the present invention, refers to fiber that may have cross section
shape in wave form, and specifically, its shape is illustrated in
FIG. 5.
[0039] The sound-absorbing material with excellent sound-absorbing
performance of the present invention can improves sound absorption
coefficient and transmission loss by forming large surface area and
air layer, so as to induce viscosity loss of incident sound energy.
Further, it makes light-weight design thereof possible since it can
provide excellent sound-absorbing performance using reduced amount
of fiber, and can improve sound-absorbing performance by using
binder fiber having rebound resilience, so as to maintain enough
bonding strength between fibers and also to maximize viscosity loss
of sound energy transmitted to fiber structure.
[0040] Accordingly, a sound-absorbing material having excellent
sound-absorbing performance, which can be used for improving noise
insulation performance of electric devices and the like using motor
parts as well as used through transport such as vehicle, train,
ship, aircraft and the like, and a method for manufacturing thereof
can be provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a six-pointed star shaped non-circular shaped
fiber, which is contained in the sound-absorbing material according
to a preferred embodiment of the present invention;
[0042] FIG. 2 is a 3-bar flat type non-circular shaped fiber, which
is contained in the sound-absorbing material according to a
preferred embodiment of the present invention;
[0043] FIG. 3 is a 6-leaf type non-circular shaped fiber, which is
contained in the sound-absorbing material according to a preferred
embodiment of the present invention;
[0044] FIG. 4 is a 8-leaf type non-circular shaped fiber, which is
contained in the sound-absorbing material according to a preferred
embodiment of the present invention;
[0045] FIG. 5 is a wave type non-circular shaped fiber, which is
contained in the sound-absorbing material according to a preferred
embodiment of the present invention;
[0046] FIG. 6 is a 8-leaf type non-circular shaped fiber, which is
contained in the sound-absorbing material according to a preferred
embodiment of the present invention;
[0047] FIG. 7 is a 8-leaf type non-circular shaped fiber, which is
contained in the sound-absorbing material according to a preferred
embodiment of the present invention; and
[0048] FIG. 8 is a drawing showing L and W of the 8-leaf type
non-circular shaped fiber according to a preferred embodiment of
the present invention as an example.
DETAILED DESCRIPTION
[0049] Hereinafter reference will now be made in detail to various
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings and described below. While
the invention will be described in conjunction with exemplary
embodiments, it will be understood that present description is not
intended to limit the invention to those exemplary embodiments. On
the contrary, the invention is intended to cover not only the
exemplary embodiments, but also various alternatives,
modifications, equivalents and other embodiments, which may be
included within the spirit and scope of the invention as defined by
the appended claims.
[0050] As described above, since in the conventional
sound-absorbing material for a fiber structure, surface density and
thickness of fiber aggregate are increased in order to improve
sound-absorbing performance and noise insulation performance by
increasing porosity and sound wave dissipation route, the vehicle
becomes heavier thereby deteriorating fuel efficiency. Further,
when low melting polyester binder fiber is used for the
conventional sound-absorbing material for a fiber structure, the
fiber aggregate may be hardened. Thus, there was a problem that
sound absorption coefficient of low frequency is reduced since
vibration generated by sound wave propagation and transmitted to
matrix structure is not fully attenuated.
[0051] Accordingly, the present invention provides a
sound-absorbing material which comprises: a non-circular shaped
fiber satisfying the following Formula 1; and a binder fiber which
partly binds a plurality of the non-circular shaped fibers, to find
solutions for the above described problems.
1.5 .ltoreq. P 4 .times. .pi. .times. A Formula 1 ##EQU00003##
[0052] (A: Fiber cross sectional area (.mu.m.sup.2), P:
Circumference length of fiber cross section (.mu.m))
[0053] As such, sound absorption coefficient and transmission loss
may be improved by forming large surface area and air layer, so as
to induce viscosity loss of incident sound energy. Further, -weight
design thereof may be obtained because excellent sound-absorbing
performance may be obtained using reduced amount of fiber, and
sound-absorbing performance may be improved by using binder fiber
having rebound resilience, so as to maintain enough binding
strength between fiber and also to maximize viscosity loss of sound
energy transmitted to a fiber structure. Thus, a sound-absorbing
material having excellent sound-absorbing performance, which can be
used for improving noise insulation performance of electric devices
and the like using motor parts as well as used through transport
such as vehicle, train, ship, aircraft and the like, and a method
for manufacturing thereof may be provided.
[0054] In general, when sound wave conflicts with a certain
material, it may cause viscosity loss, thereby causing noise
reduction while mechanical energy of the sound wave is converted to
thermal energy. In order to reduce noise by increasing energy loss
rate against sound wave introduced to the fiber aggregate with the
same weight, it is advantageous to increase surface area of fiber
where viscosity loss of sound wave occurs.
[0055] The non-circular shaped fiber satisfy the .eta. value of 1.5
or greater, calculated as
.eta. = P 4 .times. .pi. .times. A ##EQU00004##
[0056] (A: Fiber cross sectional area (.mu.m.sup.2), P:
Circumference length of fiber cross section (.mu.m)), and it may
secure greater surface area than the fiber used to the conventional
sound-absorbing material for a fiber structure, and improve sound
absorption coefficient and transmission loss. When the .eta. value
is less than 1.5, the fiber surface area may be small. Thus, there
is a problem that light-weight design thereof may be impossible
because a large amount of fiber needs to effectively embody
sound-absorbing performance. The higher .eta. value means the
greater fiber surface area. Accordingly, more preferably, the
non-circular shaped fiber used in the present invention may have
the .eta. value of 2.6 or greater, and more preferably the value
may be 3.0 to 7.0. If the .eta. value of the non-circular shaped
fiber used in the present invention is greater than 7.0, there may
be a problem that production cost may be increased due to increase
of nozzle production cost, facilities replacement related to
cooling efficiency improvement, polymer modification for
solidification rate improvement, productivity reduction and the
like.
[0057] The non-circular shaped fiber of the present invention,
which satisfies the .eta. value of 1.5 or greater, may be a
six-pointed star shape, 3-bar flat type, 6-leaf type, 8-leaf type
or wave type, or a combination thereof. In the case of the wave
type, when the .eta. value satisfies 1.5 or greater, specific shape
such as the number of the curved point in the wave shape, length
and width of the cross section and the like may vary. The number of
the curved point in the wave shape means the point where the
direction is changed to the length direction of the cross section,
and for example, the number of the curved point of the wave type
non-circular shaped fiber in FIG. 5 is 4.
[0058] Specifically, FIG. 1 is six-pointed star shape non-circular
shaped fiber according to a preferred embodiment of the present
invention, and its .eta. value is 1.51, and FIG. 2 is 3-bar flat
type non-circular shaped fiber according to a preferred embodiment
of the present invention, and its .eta. value is 1.60. Further,
FIG. 3 is 6-leaf type non-circular shaped fiber according to a
preferred embodiment of the present invention, and its .eta. value
is 1.93, FIG. 4 is 8-leaf type non-circular shaped fiber according
to a preferred embodiment of the present invention, and its .eta.
value is 2.50, FIG. 5 is wave type non-circular shaped fiber
according to a preferred embodiment of the present invention, and
its .eta. value is 2.55, FIG. 6 is 8-leaf type non-circular shaped
fiber according to a preferred embodiment of the present invention,
and its .eta. value is 2.8, and FIG. 7 is 8-leaf type non-circular
shaped fiber according to a preferred embodiment of the present
invention, and its 11 value is 3.2.
[0059] The .eta. value of a general circular type fiber with
circular cross section is 1.0, and its sound absorption coefficient
and transmission loss are significantly reduced because its surface
area is not large enough (see Comparative Example 1), and although
the non-circular shaped fiber are a six-pointed star shape, 3-bar
flat type, 6-leaf type, 8-leaf type or wave type, if the .eta.
value does not satisfy 1.5 or greater, the surface area which can
generate viscosity loss of the sound energy is not enough.
Accordingly, those are not suitable as the non-circular shaped
fiber used for the sound-absorbing material of the present
invention (see Comparative Examples 2 to 5).
[0060] More preferably, the non-circular shaped fiber used in the
present invention may have the L/W value of 2 to 3. L is the
abbreviation for Length which is vertical length of fiber, and W is
the abbreviation for Width which is length against horizontal
direction connecting between angular points. Specifically, FIG. 8
shows L and W values of the 8-leaf type non-circular shaped fiber.
In the case of the cross section of the 8-leaf type non-circular
shaped fiber, when the longer direction is called vertical length,
the length may be expressed as L, and in the 3 shorter shape, the
distance between angular points may be expressed as W.
[0061] Further, the non-circular shaped fiber used in the present
invention may have 6 to 8 angular points more preferably, but it is
not limited to the L/W or the number of the angular point. The
non-circular shaped fiber which satisfies the .eta. value of 1.5 or
greater may be preferred.
[0062] Length of the non-circular shaped fiber may be 35 to 65 mm.
When it is less than 35 mm, it may be difficult to form and produce
fiber aggregate due to wide gap between the fibers, and
sound-absorbing and noise insulation performance may be reduced due
to excess porosity. When it is over 65 mm, porosity may be reduced
due to too narrow gap between the fibers, thereby reducing sound
absorption coefficient. Further, fineness of the non-circular
shaped fiber may be 1.0 to 7.0 De, and it may be more effective to
sound-absorbing performance as fineness becomes lower. When the
fineness of the non-circular shaped fiber is less than 1.0 De,
there may be a problem to control the optimum shape of the targeted
cross section, and when it is greater than 7.0 De (denier), there
may be a difficulty on non-woven fiber manufacturing process and a
problem of reduction of sound-absorbing performance when it is
manufactured as the fiber aggregate.
[0063] The material of the non-circular shaped fiber included in
the sound-absorbing material of the present invention may be
preferably polyethylene terephthalate (PET), but not particularly
limited thereto. Polypropylene (PP), rayon, and any polymer that
may be spun in fiber form may be used preferably as a
sound-absorbing material.
[0064] Further, the sound-absorbing material of the present
invention contains binder fiber which partly binds a plurality of
the non-circular shaped fibers.
[0065] The binder fiber may be any binder fiber which is generally
used when manufacturing fiber structure, and it may be used in the
form of powder as well as fiber, and more particularly, it may
contain low melting (LM) elastomer. The elastomer generally refers
to a polymer material having excellent elasticity such as rubbers,
and i.e., it means a polymer having a characteristic that stretches
when it is pulled by external force, and it is back to the original
length when the external force is removed. The preferable LM
elastomer used in the present invention may have elastic recovery
modulus of 50 to 80%. When elastic recovery modulus is less than
50%, the fiber aggregate is hardened, and sound-absorbing
performance may be reduced due to short flexibility. When it is
greater than 80%, there may be problems that processability may be
reduced when manufacturing the fiber aggregate, as well as
production cost of the polymer itself may be increased.
[0066] In the past, after the binder fiber was melted down and
bound major fiber together, the fiber aggregate was hardened such
that there was a problem that sound absorption coefficient was
reduced because vibration generated by sound wave propagation and
transmitted to matrix structure was not fully attenuated. However,
in the present invention, rebound resilience rate (ASTM D 3574) of
fiber structure is increased up to 50 to 80% by containing a LM
elastomer having elastic recovery modulus of 50 to 80% in the
binder fiber of the fiber aggregate, and attenuation capability for
the vibration which is ultimately transmitted inside the matrix is
improved, and thus sound absorption coefficient and transmission
loss may be improved.
[0067] The LM elastomer may be a polyester-based polymer, a
polyamide-based polymer, a polystyrene-based polymer, a
polyvinylchloride-based polymer or polyurethane-based polymer, or
combinations thereof
[0068] Further, more preferably, the LM elastomer may be
manufactured by esterification and polymerization steps using
dimethyl terephthalate(DMT) and dimethyl isophthalate(DMI), or
terephthalic acid(TPA) and isophthalic acid(IPA) as an acid
ingredient(Diacid); and 1,4-butanediol(1,4-BD) and
polytetramethyleneglycol(PTMG) as a diol ingredient (Diol).
[0069] The acid ingredient (Diacid) uses dimethyl terephthalate
(DMT) and dimethyl isophthalate (DMI), or terephthalic acid (TPA)
and isophthalic acid (IPA). The dimethyl terephthalate (DMT) and
terephthalic acid (TPA) form a crystal region by reacting with the
diol ingredient, and the dimethyl isophthalate (DMI) and
isophthalic acid (IPA) form a non-crystal region by reacting with
the diol ingredient, thereby providing low melting function and
elasticity.
[0070] Mixing ratio of dimethyl terephthalate (DMT) and dimethyl
isophthalate (DMI) may be a molar ratio of
0.65.about.0.80:0.2.about.0.35, preferably, and mixing ratio of
terephthalic acid (TPA) and isophthalic acid (IPA) also may be
molar ratio of 0.65.about.0.80:0.2.about.0.35, preferably. When the
molar ratio of dimethyl isophthalate (DMI) and isophthalic acid
(IPA) is less than the above described range, elastic recovery
modulus may be deteriorated, and the low melting function may not
be expressed. When the molar ratio of dimethyl isophthalate (DMI)
and isophthalic acid (IPA) is greater than the above described
range, physical properties may be deteriorated.
[0071] The diol ingredient (Diol) uses 1,4-butanediol (1,4-BD),
polytetramethyleneglycol(PTMG), and 1,4-butanediol forms a crystal
region by reacting with acid ingredient and
polytetramethyleneglycol(PTMG) forms a non-crystal region by
reacting with acid ingredient, thereby providing low-melting
function and elasticity.
[0072] Mixing ratio of the 1,4-butanediol (1,4-BD),
polytetramethyleneglycol (PTMG may be a molar ratio of
0.85.about.0.95:0.05.about.0.15, preferably. When the molar ratio
of polytetramethyleneglycol (PTMG) is less than the above described
range, elastic recovery modulus may be deteriorated, and the
low-melting function may not be expressed. When the molar ratio of
polytetramethyleneglycol (PTMG) is greater than the above described
range, physical properties may be deteriorated. 1,4-butanediol
(1,4-BD) may be used as a mixture with ethyleneglycol (EG) within
the above described range.
[0073] Further, molecular weight of the polytetramethyleneglycol
(PTMG) may be in a range of 1500 to 2000, preferably. When the
molecular weight of the polytetramethyleneglycol (PTMG) is out of
the said range, elasticity and physical properties of the LM
elastomer to be manufactured may not be suitable for use.
[0074] The acid ingredient and the diol ingredient may be mixed at
molar ratio of 0.9.about.1.1:0.9.about.1.1 and polymerized,
preferably. When any one ingredient of the acid ingredient and the
diol ingredient is excessively mixed, it is not used to be
polymerized and is discarded. Accordingly, it is preferred to mix
the acid ingredient and the diol ingredient at similar amounts.
[0075] As described above, the LM elastomer manufactured from
dimethyl terephthalate(DMT), dimethyl isophthalate(DMI) as the acid
ingredient(Diacid) and 1,4-butanediol(1,4-BD),
polytetramethyleneglycol(PTMG) as the diol ingredient(Diol) is
manufactured to have melting point of 150.about.180.degree. C. and
elastic recovery modulus of 50.about.80%.
[0076] Further, the binder fiber of the sound-absorbing material of
the present invention may be a conjugated fiber which is
conjugate-spun by using the LM elastomer as one component. More
preferably, it may be sheath-core type or side by side type
conjugated fiber. When the sheath-core type conjugated fiber is
formed, the LM elastomer may be used as a sheath ingredient, and
general polyester may be used as a core ingredient. The general
polyester reduces production cost and functions as fiber supporter,
and the LM elastomer allows to express elasticity and low melting
function.
[0077] Preferably, the binder fiber may be manufactured by using
the LM elastomer and the general polyester at weight ratio of
40:60.about.60:40. When the LM elastomer is contained at weight
ratio of less than 40, elasticity and low melting function may be
deteriorated, and when it is contained at weight ratio of over 60,
there is a problem of increase of production cost.
[0078] The sound-absorbing material may contain the non-circular
shaped fiber of 50 to 80 wt % based on the total weight of the
sound-absorbing material and the binder fiber of 20 to 50 wt %
based on the total weight of the sound-absorbing material. When the
content of the non-circular shaped fiber is less than 50 wt %, it
may be difficult to embody the optimal sound-absorbing and noise
insulation performances due to reduced fiber surface area, but when
the content of the non-circular shaped fiber is greater than 80 wt
%, the content of the binder fiber becomes less than 20 wt %,
relatively, and it may be difficult to maintain enough binding
strength between the fiber. Thus, it may be difficult to form the
sound-absorbing material to a certain shape and the vibration,
which is generated from sound wave propagation and transmitted to
the matrix structure, is not fully attenuated because the matrix
structure is not strong, such that low frequency sound absorption
coefficient may be reduced. As the content of the binder fiber is
increased to 20 to 50 wt %, rebound elasticity modulus (ASTM D
3574) increases up to 50 to 80%.
[0079] This fiber structure with polymorphic cross section having
excellent sound-absorbing performance is manufactured by a method
for manufacturing a sound-absorbing material that comprises forming
fiber aggregate in the nonwoven fabric fabric form. The fiber
aggregate comprises: a non-circular shaped fiber satisfying the
following Formula 1; and binder fiber which partly binds a
plurality of the non-circular shaped fibers.
1.5 .ltoreq. P 4 .times. .pi. .times. A Formula 1 ##EQU00005##
[0080] (A: Fiber cross sectional area (.mu.m.sup.2), P:
Circumference length of fiber cross section (.mu.m))
[0081] The sound-absorbing material may be manufactured by forming
the fiber aggregate containing the non-circular shaped fiber and
the binder fiber in the non-woven form having a certain surface
density by general manufacturing processes for a fiber structure
sound-absorbing material such as needle punching process or thermal
adhesion process and the like. Hereinafter, detailed description
about the above-described non-circular shaped fiber and the binder
fiber, which are identically applied to the method for
manufacturing the sound-absorbing material of the present invention
will be omitted.
EXAMPLES
[0082] The following examples illustrate the invention and are not
intended to limit the same.
Example 1
[0083] Polyester-based 8-leaf type (FIG. 4, .eta.=2.5) non-circular
shaped fiber (6.5 De, 61 mm, strength 5.8 g/D, elongation rate 40%,
crimp number 14.2/inch) and sheath-core type conjugated fiber
containing polyester-based LM elastomer as binder fiber were mixed
at weight ratio of 8:2, the mixture was physically broken down
through needle punching process after controlling weight
constantly, and then non-woven type fiber aggregate having
thickness of 20 mm and surface density of 1600 g/m.sup.2 was
manufactured through a general thermal adhesion process. Rebound
resilience of the manufactured sound-absorbing material was
55%.
[0084] The sheath-core type conjugated fiber containing
polyester-based LM elastomer as binder fiber contained
polyester-based LM elastomer as a sheath ingredient, and the
polyester-based LM elastomer used a mixture of terephthalic acid of
75 mole % and isophthalic acid of 25 mole % as an acid ingredient
and a mixture of polytetramethyleneglycol of 8.0 mole % and
1,4-butanediol of 92.0 mole % as a diol ingredient, and
manufactured by mixing and polymerizing the acid ingredient and the
diol ingredient at molar ratio of 1:1. The LM elastomer
manufactured as mentioned above has melting point of 50.degree. C.,
intrinsic viscosity of 1.4 and elastic recovery modulus of 80%. As
the core ingredient, polyethylene terephthalate(PET) having melting
point of 260.degree. C. and intrinsic viscosity of 0.65 was used,
and conjugated fiber having fineness of 6 D, strength of 3.0 g/D,
elongation rate of 80%, crimp number of 12/inch and fiber length of
64 mm was manufactured by spinning using a conjugate spinning
nozzle, which can conjugate spin the polyester-based LM elastomer
and the general PET at spinning temperature of 275.degree. C. and
winding speed of 1,000 mm/min, elongated by 3.3 folds at 77.degree.
C., and finally heated at 140.degree. C.
Example 2
[0085] The procedure of Example 1 was repeated except for
manufacturing non-woven type fiber structure having thickness of 20
mm, surface density of 1200 g/m.sup.2.
Example 3
[0086] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using six-pointed star
shaped (FIG. 1, .eta.=1.51) non-circular shaped fiber.
Example 4
[0087] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using 3-bar flat type
(FIG. 2, .eta.=1.60) non-circular shaped fiber.
Example 5
[0088] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using 6-leaf type (FIG. 3,
.eta.=1.93) non-circular shaped fiber.
Example 6
[0089] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using wave type (FIG. 5,
.eta.=2.55) non-circular shaped fiber.
Example 7
[0090] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using 8-leaf type (FIG. 6,
.eta.=2.8) non-circular shaped fiber non-circular shaped fiber.
Example 8
[0091] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using 8-leaf type (FIG. 7,
.eta.=3.2) non-circular shaped fiber non-circular shaped fiber.
Example 9
[0092] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using low melting PET
fiber as binder fiber. Rebound resilience of the manufactured
sound-absorbing material was 30%.
Comparative Example 1
[0093] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using circular (.eta.=1.0)
shaped fiber.
Comparative Example 2
[0094] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using five-pointed star
shape (.eta.=1.30) non-circular shaped fiber.
Comparative Example 3
[0095] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using wave type
(.eta.=1.42) non-circular shaped fiber.
Comparative Example 4
[0096] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using Y type (.eta.=1.26)
non-circular shaped fiber.
Comparative Example 5
[0097] The procedure of Example 1 was repeated except for
manufacturing a sound-absorbing material using six-pointed star
shape (.eta.=1.41) non-circular shaped fiber.
Test Example
[0098] In order to evaluate sound-absorbing and noise insulation
performances of the sound-absorbing materials manufactured
according to Examples 1 to 9 and Comparative Examples 1 to 5, the
materials were tested as the following measuring methods, and the
results were shown in Tables 1 and 2.
[0099] 1. Sound Absorption Coefficient
[0100] In order to measure sound absorption coefficient, 3
specimens applicable to ISO R 354, Alpha Cabin method were
manufactured, respectively, sound-absorbing coefficients were
measured and the mean of the measured sound-absorbing coefficients
were shown in Table 1.
[0101] 2. Transmission Loss
[0102] In order to measure noise insulation effect, 3 specimens
applicable to a transmission loss coefficient evaluating device
(APAMAT-II) were manufactured, respectively, insertion loss was
measured, and the mean value of the measured insertion loss was
shown in Table 2.
[0103] 3. Elastic Recovery Modulus
[0104] A dumbbell shape specimen having thickness of 2 mm and
length of 10 cm was elongated 200% at a rate of 200%/min using
Instron, waited for 5 sec, and the elongated length after recovered
at the same rate was measured, and then elastic recovery modulus
was calculated by the following Formula.
Elasticity Recovery Rate ( % ) = 20 - ( L - 10 ) 20 .times. 100 ( L
: Elongated Length ) ##EQU00006##
[0105] 4. Rebound Resilience Rate (Ball Rebound)
[0106] After dropping a metal ball from a certain height to a test
specimen, the height of the rebound ball was measured (JIS K-6301,
unit: %). Test specimen was made into a square having a side length
of 50 mm or greater and thickness of 50 mm or greater, and a steel
ball having weight of 16 g and diameter of 16 mm was dropped from a
height of 500 mm to the test specimen, and then the maximum rebound
height was measured. Then, for each 3 test specimens, the rebound
value was measured at least 3 times in a raw within 1 min, and the
median value was used as rebound resilience rate (%).
TABLE-US-00001 TABLE 1 Sound absorption coefficient per frequency
(Hz) 1000 Hz 2000 Hz 3150 Hz 5000 Hz Example 1 0.67 0.75 0.84 0.96
Example 2 0.54 0.63 0.77 0.85 Example 3 0.62 0.67 0.78 0.88 Example
4 0.59 0.71 0.81 0.90 Example 5 0.62 0.69 0.80 0.90 Example 6 0.66
0.77 0.85 0.97 Example 7 0.67 0.78 0.89 0.99 Example 8 0.68 0.79
0.91 1.00 Example 9 0.50 0.70 0.79 0.89 Comparative 0.51 0.61 0.74
0.83 Example 1 Comparative 0.57 0.65 0.75 0.86 Example 2
Comparative 0.57 0.62 0.76 0.86 Example 3 Comparative 0.56 0.64
0.75 0.85 Example 4 Comparative 0.61 0.65 0.75 0.86 Example 5
TABLE-US-00002 TABLE 2 Transmission loss (dB) per frequency (Hz)
1000 Hz 2000 Hz 3150 Hz 5000 Hz Example 1 25 27 35 43 Example 2 23
24 32 41 Example 3 22 25 32 40 Example 4 24 25 33 41 Example 5 24
26 33 41 Example 6 25 27 35 44 Example 7 26 28 36 45 Example 8 27
30 38 47 Example 9 21 24 31 40 Comparative 22 23 31 40 Example 1
Comparative 21 24 31 40 Example 2 Comparative 22 24 32 41 Example 3
Comparative 21 24 31 40 Example 4 Comparative 22 24 32 40 Example
5
[0107] As shown in Tables 1 and 2, as comparing the results of
measuring sound-absorbing and noise insulation performances in
Examples 1 to 9 and Comparative Examples 1 to 5, it was found that
sound-absorbing and noise insulation performances of the fiber
aggregate were improved as the fiber surface areas were
increased.
[0108] Specifically, as comparing the result of measuring
performances of Example 2 and Comparative Example 1, it was found
that the sound-absorbing material using the non-circular shaped
fiber of the present invention had better sound-absorbing and noise
insulation performances than the fiber sound-absorbing material
using fiber with circular cross section generally used, despite the
reduced surface density of the fiber aggregate, and therefore,
light-weight design thereof is possible by using reduced amount of
fiber.
[0109] It is found that Examples 1 to 9 satisfying the .eta. value
of 1.5 or greater had improved sound absorption coefficient and
transmission loss than Comparative Examples 1 to 5 having the .eta.
value of less than 1.5. It was found that Comparative Example 5
having the value of less than 1.5 also had low effect on sound
absorption coefficient and transmission loss due to small surface
area, although six-pointed star shape non-circular shaped fiber was
used.
[0110] Further, as comparing the results of measuring performances
of Example 9 using the low melting PET fiber as binder fiber and
Examples 1 to 8 using the low melting elastomer, it was found that
flexible structure having rebound elasticity rate of 55% was
obtained by using low melting elastomer as binder fiber, and
sound-absorbing performance was improved by improved attenuation
capability of the vibration transmitted to the matrix
structure.
* * * * *