U.S. patent application number 16/760267 was filed with the patent office on 2020-08-13 for spunbonded nonwoven fabric.
This patent application is currently assigned to Toray Industries, Inc.. The applicant listed for this patent is Toray Industries, Inc.. Invention is credited to Masanori Endo, Ryoichi Hane, Yohei Nakano.
Application Number | 20200255994 16/760267 |
Document ID | / |
Family ID | 66331887 |
Filed Date | 2020-08-13 |
United States Patent
Application |
20200255994 |
Kind Code |
A1 |
Endo; Masanori ; et
al. |
August 13, 2020 |
SPUNBONDED NONWOVEN FABRIC
Abstract
A spunbonded nonwoven fabric of the present invention is
characterized by being composed of a polyolefin fiber, wherein the
average pore diameter of the nonwoven fabric surface is 0.1-25
.mu.m, the maximum pore diameter is 50 .mu.m or less, and the water
pressure resistance per unit basis weight is 7
mmH.sub.2O/(g/m.sup.2) or more.
Inventors: |
Endo; Masanori; (Otsu-shi,
Shiga, JP) ; Nakano; Yohei; (Otsu-shi, Shiga, JP)
; Hane; Ryoichi; (Otsu-shi, Shiga, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Toray Industries, Inc. |
Tokyo |
|
JP |
|
|
Assignee: |
Toray Industries, Inc.
Tokyo
JP
|
Family ID: |
66331887 |
Appl. No.: |
16/760267 |
Filed: |
October 30, 2018 |
PCT Filed: |
October 30, 2018 |
PCT NO: |
PCT/JP2018/040408 |
371 Date: |
April 29, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D04H 3/007 20130101;
D01F 6/46 20130101; D10B 2321/022 20130101; D04H 3/16 20130101 |
International
Class: |
D04H 3/007 20060101
D04H003/007; D01F 6/46 20060101 D01F006/46; D04H 3/16 20060101
D04H003/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 1, 2017 |
JP |
2017-211607 |
Jul 27, 2018 |
JP |
2018-141052 |
Claims
1. A spun-bonded nonwoven fabric composed of polyolefin fibers,
wherein a surface of the nonwoven fabric has an average pore
diameter of 0.1 to 25 .mu.m, and a maximum pore diameter of 50 pm
or less, and the nonwoven fabric has water pressure resistance per
unit basis weight of 7 mmH.sub.2O/(g/m.sup.2) or more.
2. The spun-bonded nonwoven fabric according to claim 1, wherein
the fiber constituting the nonwoven fabric has an average single
fiber diameter of 6.5 to 11.9 .mu.m.
3. The spun-bonded nonwoven fabric according to claim 1, wherein a
kinetic friction coefficient between the fibers constituting the
nonwoven fabric is 0.01 to 0.3.
4. The spun-bonded nonwoven fabric according to claim 1, wherein
the fiber constituting the nonwoven fabric has an MFR of 155 to 850
g/10 min.
5. The spun-bonded nonwoven fabric according to claim 1, wherein
the fiber constituting the nonwoven fabric comprises a fatty acid
amide compound having 23 or more and 50 or less carbon atoms.
6. The spun-bonded nonwoven fabric according to claim 5, wherein an
addition amount of the fatty acid amide compound is 0.01% to 5.0%
by mass.
7. The spun-bonded nonwoven fabric according to claim 5, wherein
the fatty acid amide compound is ethylene bisstearic acid
amide.
8. The spun-bonded nonwoven fabric according to claim 6, wherein
the fatty acid amide compound is ethylene bisstearic acid
amide.
9. The spun-bonded nonwoven fabric according to claim 2, wherein
the fiber constituting the nonwoven fabric comprises a fatty acid
amide compound having 23 or more and 50 or less carbon atoms.
10. The spun-bonded nonwoven fabric according to claim 9, wherein
an addition amount of the fatty acid amide compound is 0.01% to
5.0% by mass.
11. The spun-bonded nonwoven fabric according to claim 9, wherein
the fatty acid amide compound is ethylene bisstearic acid
amide.
12. The spun-bonded nonwoven fabric according to claim 10, wherein
the fatty acid amide compound is ethylene bisstearic acid amide.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is the U.S. National Phase application of
PCT/JP2018/040408, filed Oct. 30, 2018, which claims priority to
Japanese Patent Application No. 2017-211607, filed Nov. 1, 2017 and
Japanese Patent Application No. 2018-141052, filed Jul. 27, 2018,
the disclosures of each of these applications being incorporated
herein by reference in their entireties for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to a spun-bonded nonwoven
fabric composed of polyolefin fibers, which is excellent in
waterproofness and softness, and is excellent in moldability as
building material applications.
BACKGROUND OF THE INVENTION
[0003] In recent years, nonwoven fabrics have been used in various
applications and are expected to grow in the future. The nonwoven
fabrics are employed in a wide range of applications such as
industrial materials, civil engineering materials, building
materials, living materials, agricultural materials, sanitary
materials, and medical materials.
[0004] Building materials draw attention as an application of
nonwoven fabrics. In recent construction of buildings such as a
wooden house, a ventilation layer construction method has been
widely employed. In the method, a ventilation layer is provided
between an outer wall material and a heat insulation material, and
moisture that has penetrated into a wall body is released to the
outside through the ventilation layer. In the ventilation layer
construction method, a spun-bonded nonwoven fabric is utilized as a
house wrapping material which is a breathable-waterproof sheet
having both waterproofness of preventing rainwater from
infiltrating from the outside of a building and breathability of
allowing moisture in the wall escape to the outside. The
spun-bonded nonwoven fabric is excellent in breathability because
of its structure, while it has poor waterproofness. Therefore, the
spun-bonded nonwoven fabric is made into a laminate with a film
with excellent waterproofness to make a breathable-waterproof sheet
for use as a house wrapping material.
[0005] The house wrapping material is fixed on a base by a binding
needle (also referred to as a tucker needle or a staple) and
employed in a construction work. It is thus required to have
excellent durability over a long period of time, weather resistance
under conditions of high temperature and low temperature,
durability (hydrolysis resistance) of long term use, and excellent
moldability at the time of construction.
[0006] In the related art, in order to improve the balance between
breathability and waterproofness, a house wrapping material which
is a laminate of a polyester-based nonwoven fabric having a fiber
diameter of 3 to 28 microns and a basis weight of 5 to 50
g/m.sup.2, and a film having a thickness of 7 to 60 microns made of
block copolymerized polyester having a hard segment and a soft
segment superposed on the nonwoven fabric, has been proposed (see
Patent Literature 1).
PATENT LITERATURE
[0007] Patent Literature 1: Japanese Patent No. 3656837
SUMMARY OF THE INVENTION
[0008] However, since the house wrapping material in the related
art is a laminate of a nonwoven fabric and a film, there is a
problem that the sheet is hard and has poor moldability. The
hardness and the poor moldability of the sheet are due to the film,
and reducing a proportion of the film to be bonded is effective,
but the reduction of the film proportion is restricted in view of
waterproofness.
[0009] As described above, a nonwoven fabric having both
waterproofness and softness and excellent in moldability has been
sought in the related art.
[0010] Therefore, in view of the above problems, an object of the
present invention is, as compared with the related art, to provide
a spun-bonded nonwoven fabric composed of fibers made of
polyolefin, having both waterproofness and softness and excellent
in workability.
[0011] The spun-bonded nonwoven fabric of the present invention is
composed of polyolefin fibers, in which a surface of the nonwoven
fabric has an average pore diameter of 0.1 to 25 .mu.m, a maximum
pore diameter of 50 .mu.m or less, and the spun-bonded nonwoven
fabric has water pressure resistance per unit basis weight of 7 mm
H.sub.2O/(g/m.sup.2) or more.
[0012] According to a preferred embodiment of the spun-bonded
nonwoven fabric of the invention, the polyolefin fiber constituting
the nonwoven fabric has an average single fiber diameter of 6.5 to
11.9 .mu.m.
[0013] According to a preferred embodiment of the spun-bonded
nonwoven fabric of the invention, a kinetic friction coefficient
between the polyolefin fibers constituting the nonwoven fabric is
0.01 to 0.3.
[0014] According to a preferred embodiment of the spun-bonded
nonwoven fabric of the invention, the fiber constituting the
nonwoven fabric has an MFR of 155 to 850 g/10 min.
[0015] According to a preferred embodiment of the spun-bonded
nonwoven fabric of the invention, the fiber constituting the
nonwoven fabric includes a fatty acid amide compound having 23 or
more and 50 or less carbon atoms.
[0016] According to a preferred embodiment of the spun-bonded
nonwoven fabric of the invention, an addition amount of the fatty
acid amide compound is 0.01% to 5.0% by mass.
[0017] According to a preferred embodiment of the spun-bonded
nonwoven fabric of the invention, the fatty acid amide compound is
ethylene bisstearic acid amide.
[0018] According to the present invention, a spun-bonded nonwoven
fabric that is composed of polyolefin fibers with good spinnability
and high productivity despite of their small single fiber diameter,
has uniform texture, a smooth surface and excellent softness, a
small pore diameter size of the nonwoven fabric, and high water
resistance, can be obtained. Based on these characteristics, the
spun-bonded nonwoven fabric of the present invention can be
suitably utilized as a breathable-waterproof sheet application in
particular.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0019] The spun-bonded nonwoven fabric of the present invention is
a spun-bonded nonwoven fabric composed of polyolefin fibers, in
which the nonwoven fabric has an average pore diameter size of 0.1
to 25 .mu.m, a maximum pore diameter size of 50 .mu.m or less, and
the nonwoven fabric has a water pressure resistance per unit basis
weight of 7 mmH.sub.2O/(g/m.sup.2) or more.
[0020] Accordingly, a spun-bonded nonwoven fabric having a small
pore diameter on a surface of the nonwoven fabric and excellent in
water resistance can be made, and a spun-bonded nonwoven fabric
having the required level of waterproofness and workability for a
breathable-waterproof sheet such as a house wrapping material can
be made.
[0021] For the polyolefin-based resin in the present invention,
examples of a polypropylene-based resin include a propylene
homopolymer or a copolymer of propylene and various
.alpha.-olefins, and examples of a polyethylene-based resin include
an ethylene homopolymer or a copolymer of ethylene and various
.alpha.-olefins, and the polypropylene-based resin is particularly
preferably employed in view of characteristics of spinnability and
strength.
[0022] In the polyolefin-based resin in the present invention, a
proportion of the propylene homopolymer is preferably 60% by mass
or more, more preferably 70% by mass or more, and even more
preferably 80% by mass or more. By setting so, good spinnability is
maintained and strength is improved.
[0023] The polyolefin-based resin to be employed in the present
invention may be a mixture of two or more polyolefin-based resins.
A resin composition containing another olefin-based resin, a
thermoplastic elastomer, etc. may also be employed.
[0024] A melt flow rate (may be abbreviated as MFR) of the
polyolefin resin included in the spun-bonded nonwoven fabric of the
present invention (polypropylene: ASTM D1238, load: 2160 g,
temperature: 230.degree. C., polyethylene: ASTM D1238, load: 2160
g, temperature: 190.degree. C.) is preferably 155 to 850 g/10 min,
more preferably 155 to 600 g/10 min, and even more preferably 155
to 400 g/10 min. Further, two or more resins having different MFR
can be blended at any proportion to adjust the MFR of the
polyolefin resin. By setting the MFR in a range of 155 to 850 g/10
min, performing stable spinning becomes easier, development of
orientation crystallization becomes easier, and obtaining
high-strength fibers becomes easier.
[0025] Certainly, two or more resins having different MFR can be
blended at any proportion to adjust the MFR of the polyolefin-based
resin. In this case, an MFR of the resin to be blended with the
main polyolefin-based resin is preferably 10 to 1000 g/10 min, more
preferably 20 to 800 g/10 min, and even more preferably 30 to 600
g/10 min. By setting so, it is possible to prevent the partial
occurrence of viscosity unevenness in the blended polyolefin-based
resin, resulting in non-uniform fineness, and to prevent the
spinnability from deterioration.
[0026] In addition, when fibers, which will be described later, are
spun, resins to be used may be decomposed to adjust MFR for
preventing the partial occurrence of viscosity unevenness, for
making the fineness of fibers uniform, and for making fiber
diameters smaller, which will be descried later. However, a free
radical agent such as a peroxide, particularly a dialkyl peroxide
should not be added. When this method is performed, partial
viscosity unevenness occurs and the fineness becomes non-uniform,
and hence, the fiber diameter is hardly made sufficiently small,
and spinnability may be deteriorated due to the partial viscosity
unevenness and bubbles caused by cracked gas.
[0027] In the present invention, a composite fiber obtained by
combining the polyolefin resins can also be employed. Examples of a
composite form of the composite fiber include composite forms such
as a concentric core-sheath type, an eccentric core-sheath type,
and a sea-island type. Among them, the concentric core-sheath type
composite form is preferred since it has an excellent spinnability
and the fibers can be uniformly bonded to each other by thermal
bonding because of making a low melting point component serve as a
sheath component.
[0028] Additives in common use, such as an antioxidant, weathering
agent, light stabilizer, antistatic agent, antifogging agent,
antiblocking agent, lubricant, nucleator, and pigment, or other
polymers can be added to the polyolefin-based resin in the present
invention, so long as the addition thereof does not impair the
effects of the invention.
[0029] The polyolefin-based resin in the present invention has a
melting point of preferably 80.degree. C. to 200.degree. C., more
preferably 100.degree. C. to 180.degree. C., and even more
preferably 120.degree. C. to 180.degree. C. By setting the melting
point to preferably 80.degree. C. or higher, more preferably
100.degree. C. or higher, and even more preferably 120.degree. C.
or higher, heat resistance that can withstand practical use is
easily attained. By setting the melting point to preferably
200.degree. C. or lower, more preferably 180.degree. C. or lower,
the filaments discharged from a spinneret is easily cooled, fusion
of fibers are prevented and stable spinning is easily
performed.
[0030] The polyolefin fibers constituting the spun-bonded nonwoven
fabric in the present invention preferably have an average single
fiber diameter of 6.5 to 11.9 .mu.m. By setting the average single
fiber diameter to preferably 6.5 .mu.m or more, more preferably 7.5
.mu.m or more, and even more preferably 8.4 .mu.m or more, a
decrease in spinnability can be prevented and a high-quality
nonwoven fabric can be stably produced. Meanwhile, by setting the
average single fiber diameter to preferably 11.9 .mu.m or less,
more preferably 11.2 .mu.m or less, and even more preferably 10.6
.mu.m or less, a spun-bonded nonwoven fabric having high uniformity
in the surface of the nonwoven fabric can be made, and hence a
spun-bonded nonwoven fabric with small pore diameter in the surface
thereof and with excellent water resistance that can withstand
practical use can be obtained.
[0031] The polyolefin fibers constituting the spun-bonded nonwoven
fabric in the present invention preferably has CV value of a single
fiber diameter of 0.1% to 7.0%. By setting the CV value of the
single fiber diameter to preferably 0.1% or more, more preferably
1.0% or more, and even more preferably 2.0% or more, complication
of production equipment and extreme reduction in productivity can
be prevented. Meanwhile, by setting the CV value of the single
fiber diameter to preferably 7.0% or less, more preferably 6.0% or
less, and even more preferably 5.0% or less, occurrence of a rough
feeling on the surface is prevented, and a laminated nonwoven
fabric having high uniformity can be obtained. Back pressure of a
spinneret, uniformity of yarn cooling conditions and stretching
conditions mainly affect the CV value of the single fiber diameter,
and the CV value can be controlled by appropriately adjusting
them.
[0032] The polyolefin fiber constituting the spun-bonded nonwoven
fabric in the present invention preferably has an MFR of 155 to 850
g/10 min. By setting the MFR thereof to preferably 155 to 850 g/10
min, more preferably 155 to 600 g/10 min, even more preferably 155
to 400 g/10 min, the filaments being discharged can readily follow
deformations, even when the filaments are drawn at a high spinning
speed to increase the productivity. Stable spinning is hence
possible. In addition, since stable drawing at a high spinning
speed is possible, orientation and crystallization of the fibers
can be promoted to impart high mechanical strength to the
polyolefin fibers.
[0033] In a preferred embodiment of the spun-bonded nonwoven fabric
of the present invention, from the standpoint of improving
slipperiness between the fibers, slipperiness as texture, and
softness, the polyolefin-based fibers, which are constituent
fibers, composed of polyolefin resins contain a fatty acid amide
compound having 23 or more and 50 or less carbon atoms.
[0034] It is known that the number of carbon atoms of a fatty acid
amide compound incorporated into the polyolefin fibers affects the
change in a moving speed of the fatty acid amide compound to the
fiber surface. By setting a fatty acid amide compound to preferably
have 23 or more carbon atoms, more preferably 30 or more carbon
atoms, excessive exposure of the fatty acid amide compound on the
fiber surface is inhibited, excellent spinnability and working
stability are attained, and high production efficiency is hence
maintained. Further, when the filaments are collected as a
spun-bonded nonwoven fabric web, moderate slipperiness can be
imparted to the fibers, and the uniformity of the nonwoven fabric
surface can be attained and the pore diameter of the nonwoven
fabric surface can be made smaller. Meanwhile, by setting a fatty
acid amide compound to preferably have 50 or less carbon atoms,
more preferably 42 or less carbon atoms, this fatty acid amide
compound readily migrates to the fiber surface, making it possible
to impart slipperiness between the spun-bonded nonwoven fabric
fibers or slipperiness and softness of the nonwoven fabric
surface.
[0035] Examples of the fatty acid amide compound having 23 or more
and 50 or less carbon atoms included in the present invention
include saturated fatty acid monoamide compounds, saturated fatty
acid diamide compounds, unsaturated fatty acid monoamide compounds,
and unsaturated fatty acid diamide compounds.
[0036] Specific examples of the fatty acid amide compound having 23
to 50 carbon atoms include tetradocosanoic acid amide,
hexadocosanoic acid amide, octadocosanoic acid amide, nervonic acid
amide, tetracosapentaenoic acid amide, nisinic acid amide,
ethylenebislauric acid amide, methylenebislauric acid amide,
ethylene bisstearic acid amide, ethylene bishydroxystearic acid
amide, ethylene bisbehenic acid amide, hexamethylene bisstearic
acid amide, hexamethylene bisbehenic acid amide, hexamethylene
hydroxystearic acid amide, distearyladipic acid amide,
distearylsebacic acid amide, ethylene bisoleic acid amide, ethylene
biserucic acid amide, and hexamethylene bisoleic acid amide. Two or
more of these amide compounds may be used in combination.
[0037] In the present invention, it is especially preferred to use
the ethylene bisstearic acid amide, which is a saturated fatty acid
diamide compound, among those fatty acid amide compounds. Ethylene
bisstearic acid amide has excellent thermal stability and is hence
usable in melt spinning. With the polyolefin-based fibers into
which ethylene bisstearic acid amide has been blended, when the
filaments are collected as the spun-bonded nonwoven fabric web
while maintaining high productivity, moderate slipperiness can be
imparted to the fibers, and the uniformity of the nonwoven fabric
surface can be attained and the pore diameter of the nonwoven
fabric surface can be made smaller.
[0038] In the present invention, an addition amount of the fatty
acid amide compound to the polyolefin fibers composed of the
polyolefin-based resin, which polyolefin fibers constituting the
spun-bond nonwoven fabric, is preferably 0.01% to 5.0% by mass. By
setting the addition amount of the fatty acid amide compound to
preferably 0.01% to 5.0% by mass, more preferably 0.1% to 3.0% by
mass, even more preferably 0.1% to 1.0% by mass, when the filaments
are collected as the spun-bonded nonwoven fabric web while
maintaining the spinnability, moderate slipperiness can be imparted
to the fibers, and the uniformity of the nonwoven fabric surface is
attained and the pore diameter of the nonwoven fabric surface can
be made smaller.
[0039] The term "addition amount" herein means the proportion by
mass percent of the fatty acid amide compound added to the
polyolefin-based fibers constituting the spun-bonded nonwoven
fabric of the invention, specifically to the whole resin
constituting the polyolefin-based fibers. For example, in the case
where the fatty acid amide compound is added only to the sheath
ingredient to be used as a component of core-sheath type composite
fibers, the proportion thereof to the sum of the core and sheath
ingredients is calculated.
[0040] A kinetic friction coefficient between the fibers
constituting the spun-bonded nonwoven fabric of the present
invention is preferably 0.01 to 0.3. By setting the kinetic
friction coefficient to 0.01 or more, preferably 0.1 or more, it is
possible to provide slipperiness between the fibers, and when the
spun-bonded nonwoven fabric web is collected, the fibers can
moderately slip, and the uniformity of the nonwoven fabric surface
can be improved. By setting the kinetic friction coefficient to 0.3
or less, preferably 0.25 or less, the nonwoven fabric surface is
not too slippery, and workability and handling properties when the
spun-bonded nonwoven fabric is used as a nonwoven fabric for
building materials become good. The kinetic friction coefficient
between spun-bonded fibers can be controlled by a polymer type, a
single fiber diameter, types of lubricant to be added to the fibers
and an addition amount thereof, and a fiber shape.
[0041] It is important that the spun-bonded nonwoven fabric of the
present invention has water pressure resistance per basis weight of
7 mmH.sub.2O/(g/m.sup.2) or more. By setting the water pressure
resistance per basis weight to 7 mmH.sub.2O/(g/m.sup.2) or more,
more preferably 8 mmH.sub.2O/(g/m.sup.2) or more, even more
preferably 9 mmH.sub.2O/(g/m.sup.2) or more, the spun-bonded
nonwoven fabric alone can be applied as a breathable-waterproof
sheet in applications where low waterproofness is required. In
addition, in bonding with a film, a proportion of the film to be
bonded can be reduced, and decrease in breathability due to the
film and workability deterioration due to a decrease in sheet
texture can be prevented. Further, in order to prevent
deterioration of workability in use as a building material
application resulting from lowered softness due to high density
spun-bonded nonwoven fabric, and to prevent reduction in
productivity due to thinning of fibers, the water pressure
resistance per basis weight is preferably 20 mmH.sub.2O/(g/m.sup.2)
or less. The water pressure resistance per basis weight can be
controlled by the single fiber diameter, the pore diameter of the
nonwoven fabric surface, apparent density, and thermocompression
bonding conditions (degree of press bonding, temperature, and
linear pressure).
[0042] It is important that the surface of the spun-bonded nonwoven
fabric of the present invention has a maximum pore diameter of 50
.mu.m or less. By setting the maximum pore diameter to 50 .mu.m or
less, preferably 45 .mu.m or less, and more preferably 40 .mu.m or
less, a decrease in water pressure resistance due to local pore
opening can be prevented. A lower limit of the maximum pore
diameter is not particularly limited, but the maximum pore diameter
is preferably 0.1 .mu.m or more in order to prevent deterioration
of workability in use as a building material application resulting
from lowered softness due to high density spun-bonded nonwoven
fabric. The maximum pore diameter of the nonwoven fabric can be
controlled by a single fiber diameter, a fiber dispersion state, a
kinetic friction coefficient between single fibers, a nonwoven
fabric basis weight, thermal bonding conditions (temperature,
pressure), and the like.
[0043] It is important that the surface of the spun-bonded nonwoven
fabric of the present invention has an average pore diameter of 0.1
.mu.m to 25 By setting the average pore diameter to 0.1 .mu.m or
more, preferably 0.5 .mu.m or more, more preferably 1.mu.m or more,
the spun-bonded nonwoven fabric can be made moderately soft, and by
setting the average pore diameter to 25 .mu.m or less, more
preferably 23 .mu.m or less, even more preferably 21 .mu.m or less,
high water resistance can be expressed. The average pore diameter
of the nonwoven fabric can be controlled by a single fiber
diameter, a fiber dispersion state, a kinetic friction coefficient
between single fibers, a nonwoven fabric basis weight, thermal
bonding conditions (temperature, pressure), and the like.
[0044] The spun-bonded nonwoven fabric of the present invention
preferably has a basis weight of 10 to 100 g/m.sup.2. By setting
the basis weight to preferably 10 g/m.sup.2 or higher, more
preferably 13 g/m.sup.2 or higher, even more preferably 15
g/m.sup.2 or higher, spun-bonded nonwoven fabric having mechanical
strength practically usable can be obtained. Meanwhile, by setting
the basis weight to preferably 100 g/m.sup.2 or lower, more
preferably 50 g/m.sup.2 or lower, and even more preferably 30
g/m.sup.2 or lower, when the spun-bonded nonwoven fabric is
employed as a house wrapping material, the weight thereof becomes
suitable for a worker to hold it in hand while carrying out the
work at the time of construction, and a laminated nonwoven fabric
excellent in handleability at the time of construction can be
obtained. The laminated nonwoven fabric has an excellent handling
properties when it is used as another application.
[0045] The spun-bonded nonwoven fabric of the present invention
preferably has a thickness of 0.05 to 1.50 mm. By setting the
thickness to preferably 0.05 to 1.50 mm, more preferably 0.08 to
1.00 mm, even more preferably 0.10 to 0.80 mm, softness and
moderate cushioning properties are provided, and when the
spun-bonded nonwoven fabric is employed as a house wrapping
material, the weight thereof becomes suitable for a worker to hold
it in hand while carrying out the work at the time of construction,
rigidity of the nonwoven fabric is not too strong, and a laminated
nonwoven fabric having excellent handleability at the time of
construction can be obtained.
[0046] The spun-bonded nonwoven fabric of the present invention
preferably has apparent density of 0.05 to 0.30 g/cm.sup.3. By
setting the apparent density to preferably 0.30 g/cm.sup.3 or less,
more preferably 0.25 g/cm.sup.3 or less, even more preferably 0.20
g/cm.sup.3 or less, deterioration of the softness of the
spun-bonded nonwoven fabric by packing the fibers tightly can be
prevented Meanwhile, by setting the apparent density to preferably
0.05 g/cm.sup.3 or more, more preferably 0.08 g/cm.sup.3 or more,
even more preferably 0.10 g/cm.sup.3 or more, a spun-bonded
nonwoven fabric having handleability and strength or softness that
can withstand practical use, while preventing occurrence of
fluffing or delamination, can be obtained.
[0047] A stress per basis weight at 5% elongation of the
spun-bonded nonwoven fabric of the present invention (hereinafter,
may also be described as 5% modulus per basis weight) is preferably
0.06 to 0.33 (N/25 mm)/(g/m.sup.2), more preferably 0.13 to 0.30
(N/25 mm)/(g/m.sup.2), even more preferably 0.20 to 0.27 (N/25
mm)/(g/m.sup.2). By setting so, it is possible to obtain a
spun-bonded nonwoven fabric that is soft and excellent in a sense
of touch while maintaining strength which renders the spun-bonded
nonwoven fabric practically usable.
[0048] In the present invention, the stress per basis weight at 5%
elongation of the spun-bonded nonwoven fabric adopts a value
measured by the following procedure in accordance with "6.3 Tensile
Strength and Elongation Rate (ISO method)" of JIS L1913: 2010.
[0049] (1) Three test pieces of 25 mm.times.300 mm per width of 1 m
are collected in a lengthwise direction (a longitudinal direction
of the nonwoven fabric) and a widthwise direction (a transverse
direction of the nonwoven fabric) of the nonwoven fabric. [0050]
(2) The test pieces are clamped and set in a tensile tester at
intervals of 200 mm. [0051] (3) A tensile test is conducted at a
tensile speed of 100 mm/min, and a stress at 5% elongation (5%
modulus) is measured. [0052] (4) An average value of the 5% modulus
in the lengthwise direction and the widthwise direction measured
for each test piece is determined, a 5% modulus per basis weight is
calculated based on the following equation, and the calculated
value is rounded off to two decimal places.
[0052] 5% modulus per basis weight ((N/25 mm)/(g/m.sup.2))=[average
value of 5% modulus (N/25 mm)]/basis weight (g/m.sup.2).
[0053] Preferred modes of a method for producing the spun-bonded
nonwoven fabric of the present invention are explained below in
detail.
[0054] The spun-bonded nonwoven fabric of the present invention is
a long fiber nonwoven fabric produced by a spun-bonding (S) method.
Examples of the method for producing the nonwoven fabric include a
spun-bonding method, a flash spinning method, a wet method, a
carding method, and an air-laid method, and the spun-bonding method
is, not only excellent in productivity and mechanical strength, but
also can reduce fluffing and falling of fibers which easily occur
in a short fiber nonwoven fabric. In addition, a plurality of
spun-bonded (S) nonwoven fabric layers are laminated, such as SS,
SSS, and SSSS, and hence productivity and texture uniformity are
improved. Thus, the method is the preferred mode.
[0055] In the spun-bonding method, first, a molten thermoplastic
resin (polyolefin-based resin) is spun from a spinneret as long
fibers, then the fibers are suctioned and stretched with compressed
air by an ejector, and subsequently the fibers are collected on a
moving net to obtain a nonwoven fiber web. Further, the obtained
nonwoven fiber web is subjected to a heat bonding treatment to
obtain a spun-bonded nonwoven fabric.
[0056] The spinneret and ejector can have various shapes including
round and rectangular shapes. A rectangular spinneret and a
rectangular ejector are preferably used in combination, because the
amount of compressed air to be used is relatively small and an
energy cost is excellent, the filaments are less likely to suffer
fusion bonding to each other or abrasion therebetween, and filament
spread is easy.
[0057] In the present invention, the polyolefin-based resin is
melted in an extruder, metered and supplied to a spinneret, and
ejected as long fibers. A spinning temperature in melting and
spinning a polyolefin-based resin is preferably 200.degree. C. to
270.degree. C., more preferably 210.degree. C. to 260.degree. C.,
even more preferably 220.degree. C. to 250.degree. C. By setting a
spinning temperature within that range, the polyolefin-based resin
can be kept in a stable molten state, making it possible to obtain
excellent spinning stability.
[0058] The back pressure of the spinneret is preferably 0.1 to 6.0
MPa. By setting the back pressure to preferably 0.1 to 6.0 MPa,
more preferably 0.3 to 6.0 MPa, even more preferably 0.5 to 6.0
MPa, occurrence of variation of the fiber diameter due to
deterioration of discharge uniformity and increase in the spinneret
size to increase the pressure resistance can be prevented. The back
pressure of the spinneret can be adjusted by a discharge pore
diameter, a discharge pore depth, and the spinning temperature of
the spinneret, and among them, the discharge pore diameter has a
large effect.
[0059] The ejected long-fiber filaments are then cooled. Examples
of methods for cooling the ejected filaments include a method in
which cold air is forcedly blown against the filaments, a method in
which the filaments are allowed to be cooled naturally at the
temperature of the atmosphere around the filaments, and a method in
which the distance between the spinneret and the ejector is
controlled. Two or more of these methods can be used in
combination. Cooling conditions may be suitably adjusted while
taking into account of the ejection rate per single hole of the
spinneret, spinning temperature, atmosphere temperature, etc.
However, in the method of forcibly blowing cool air to the
filaments, it is preferable that wind speed variation when
measuring 10 points at equal intervals in the width direction in
the area to be blown out should be 25% or less. By setting the wind
speed variation of 25% or less, more preferably 20% or less, even
more preferably 15% or less, the filaments can be uniformly cooled,
and a fiber with a small single fiber CV can be obtained. The wind
speed variation in the present invention is calculated by the
following formula.
Wind speed variation (%)=(maximum wind speed-minimum wind
speed)/average wind speed.times.100
[0060] Next, the filaments which have been cooled and solidified
are drawn and stretched by the compressed air jetted from the
ejector.
[0061] The spinning speed is preferably 3,500 to 6,500 m/min, more
preferably 4,000 to 6,500 m/min, even more preferably 4,500 to
6,500 m/min. By controlling the spinning speed to 3,500 to 6,500
m/min, the process is made to have high production efficiency and
the orientation and crystallization of the fibers are enhanced,
making it possible to obtain long fibers having high strength. The
spinnability usually becomes worse as the spinning speed increases,
making it impossible to stably produce filaments. However, as
stated above, the desired polyolefin fibers can be stably spun by
using the polyolefin-based resin having an MFR within a specific
range.
[0062] Subsequently, the long fibers obtained are collected on a
moving net to form a nonwoven fiber web. In the present invention,
the filaments come out of the ejector are ejected at a high speed
since the filaments are stretched at the high spinning speed. The
filaments so ejected at the high speed are spread under control and
are collected in a net. A spun-bonded nonwoven fabric having less
fiber entanglement and high uniformity can be hence obtained.
[0063] Examples of a method for spreading the filaments ejected
from the ejector under control include: a method in which a flat
plate is installed at an angle between the ejector and the net to
guide the filaments; a method in which a plurality of grooves
having different angles are provided on the flat plate, so that the
filaments falling along the flat plate and the filaments falling
along the grooves are separated and dispersed in a nonwoven fiber
web flow direction to spread the filaments; and a method in which a
plurality of flat plates with different angles are arranged in a
comb-tooth shape at an outlet of the ejector and the filaments are
dropped along each flat plate to be dispersed and spread in the
nonwoven fiber web flow direction.
[0064] In particular, the method in which the plurality of flat
plates with different angles are arranged in a comb-tooth shape at
the outlet of the ejector and the filaments are dropped along the
flat plates respectively is a preferred mode, since the filaments
having a thin fiber diameter are efficiently dispersed in the
nonwoven fiber web flow direction and can be spread under control
without slowing down as much as possible.
[0065] In a preferred embodiment of the present invention, a
thermal flat roll is brought into contact with the nonwoven fiber
web from one side on the net for temporary bonding. In this way, a
surface layer of the nonwoven fiber web can be prevented from being
turned over or blown when being conveyed on the net to prevent the
texture from being deteriorated, and thus conveying performance can
be improved from the collection of the filaments to the
thermocompression bonding.
[0066] The nonwoven fiber web obtained is subsequently integrated
by heat bonding, and the desired spun-bonded nonwoven fabric can be
obtained.
[0067] Examples of methods for integrating the nonwoven fiber web
by heat bonding include methods of heat bonding with various rolls
such as: hot embossing rolls which are a pair of rolls, upper and
lower, that have an engraved surface (have recesses and protrusions
on the surface) respectively; hot embossing rolls which include a
combination of a roll having a flat (smooth) surface and a roll
which has an engraved surface (has recesses and protrusions on the
surface); and hot calendar rolls which include a pair of flat
(smooth) rolls, upper and lower; and ultrasonic bonding of heat
welding by ultrasonic vibration of a horn. In a preferred
embodiment, the hot embossing rolls which are the pair of rolls,
upper and lower, that have the engraved surface (have recesses and
protrusions on the surface) respectively or the hot embossing rolls
which include the combination of the roll having the flat (smooth)
surface and the roll which has the engraved surface (has recesses
and protrusions on the surface) are used, so as to attain excellent
production efficiency, and partially impart strength to heat-bonded
portions while texture and touch which are unique to nonwoven
fabrics can be maintained in non-bonded portions.
[0068] In a preferred embodiment, a metal roll and a metal roll are
paired as surface materials of the hot embossing rolls, so as to
obtain a sufficient thermocompression bonding effect and to prevent
the engraved surface (recesses and protrusions) of one embossing
roll from being transferred to a surface of the other roll.
[0069] A proportion of an embossed bonding area by such hot
embossing rolls is preferably 5% to 30%. By setting the proportion
of the bonding area to preferably 5% or higher, more preferably 8%
or higher, even more preferably 10% or higher, strength which
renders the spun-bonded nonwoven fabric practically usable can be
obtained. Meanwhile, by setting the proportion of the bonding area
to preferably 30% or less, more preferably 25% or less, even more
preferably 20% or less, moderate softness and handling properties,
suitable for use in especially an application of building materials
can be obtained. Even when the ultrasonic bonding is used, the
proportion of the bonding area should be preferably in the same
range.
[0070] The term "proportion of bonding area" herein means a
proportion of bonded portions to the whole spun-bonded nonwoven
fabric. Specifically, in the case of heat bonding with a pair of
rolls having recesses and protrusions, the proportion of those
portions (bonded portions) of the nonwoven fiber web at which both
protrusions of the upper roll and protrusions of the lower roll
have come into contact to the whole spun-bonded nonwoven fabric. In
the case of heat bonding with a roll having recesses and
protrusions and a flat roll, that term means the proportion of
those portions (bonded portions) of the nonwoven fiber web at which
protrusions of the roll having recesses and protrusions have come
into contact to the whole spun-bonded nonwoven fabric. In the case
of ultrasonic bonding, the term means a proportion of portions
(bonded portions) which are heat welded by ultrasonic machining to
the whole spun-bonded nonwoven fabric.
[0071] The shape of the bonding portions formed by the hot
embossing rolls and ultrasonic bonding can be any of circular,
elliptic, square, rectangular, parallelogrammic, rhombic, regularly
hexagonal, and regularly octagonal shapes and the like. It is
preferable that the bonded portions are uniformly present at
constant intervals in the longitudinal direction (conveyance
direction) and the transverse direction of the spun-bonded nonwoven
fabric. This makes it possible to reduce variation in strength of
the spun-bonded nonwoven fabric.
[0072] In a preferred mode, the hot embossing rolls have a surface
temperature during heat bonding of -50.degree. C. to -15.degree. C.
with respect to the melting point of the polyolefin-based resin
being used. By setting the surface temperature of the hot rolls to
a temperature of preferably -50.degree. C. or higher, more
preferably -45.degree. C. or higher with respect to the melting
point of the polyolefin-based resin, moderate heat-bonding is
rendered and the spun-bonded nonwoven fabric with practically
usable strength can be obtained. By setting the surface temperature
of the hot embossing rolls to a temperature of preferably
-15.degree. C. or lower more preferably -20.degree. C. or lower
with respect to the melting point of the polyolefin-based resin,
excessive heat bonding can be inhibited, and moderate softness and
workability can be obtained as the spun-bonded nonwoven fabric for
building materials.
[0073] The linear pressure of the hot embossing rolls during the
heat bonding is preferably 50 to 500 N/cm. By setting the linear
pressure of the rolls to preferably 50 N/cm or higher, more
preferably 100 N/cm or higher, even more preferably 150 N/cm or
higher, moderate heat-bonding is rendered and the spun-bonded
nonwoven fabric with practically usable strength can be obtained.
Meanwhile, by setting the linear pressure of the hot embossing
rolls to preferably 500 N/cm or less, more preferably 400 N/cm or
less, even more preferably 300 N/cm or less, moderate softness and
workability can be obtained as the spun-bonded nonwoven fabric for
building materials.
[0074] In the present invention, for the purpose of adjusting the
thickness of the spun-bonded nonwoven fabric, thermocompression
bonding can be performed by a hot calendar roll including a pair of
upper and lower flat rolls before and/or after heat bonding by the
hot embossing rolls. The pair of upper and lower flat rolls means a
metal roll or an elastic roll having no recess or protrusion on a
surface of the roll, a metal roll and a metal roll can be paired or
a metal roll and an elastic roll can be paired for use. The term
"elastic roll" herein refers to a roll made of a material having
elasticity as compared with the metal roll. Examples of the elastic
roll include so-called paper rolls such as paper, cotton, and
aramid paper, or resin rolls made of urethane-based resins,
epoxy-based resins, silicon-based resins, polyester-based resins,
hard rubber, and a mixture thereof.
[0075] The spun-bonded nonwoven fabric of the present invention has
high productivity, uniform texture, a smooth surface, excellent
softness, and high water resistance, and therefore can be suitably
used as a nonwoven fabric for house wrapping for which
breathability and waterproofness are required as an application of
building materials.
EXAMPLES
[0076] Next, the spun-bonded nonwoven fabric of the present
invention will be described in detail based on Examples.
[0077] (1) Melt Flow Rate (MFR)
[0078] Melt flow rates of a polyolefin-based resin and fibers were
measured in accordance with ASTM D-1238 respectively under the
conditions of a load of 2,160 g and a temperature of 230.degree.
C.
[0079] (2) Average Single Fiber Diameter (.mu.m):
[0080] Spun filaments were drawn and stretched by an ejector and
collected on a net to obtain a nonwoven fiber web. Ten small sample
pieces were randomly collected from the nonwoven fiber web, the
surface of each sample was photographed with a microscope at a
magnification of 500 to 1,000 diameters. Ten fibers were selected
from each sample, and the hundred fibers in total were examined for
fiber width. From the average value, the average single fiber
diameter (.mu.m) was calculated.
[0081] (3) CV Value (%) of Single Fiber Diameter
[0082] A CV value of the single fiber diameter was calculated based
on the following equation from a standard deviation and the average
single fiber diameter of the single fiber diameter obtained from
the 100 fibers examined in the above (2).
CV value (%) of single fiber diameter=standard deviation/average
value.times.100
[0083] (4) Spinning Speed (m/min):
[0084] The mass per length of 10,000 m was calculated from the
average single fiber diameter and the solid density of the
polyolefin-based resin used, and the calculated value was rounded
off to the first decimal place to obtain the average single-fiber
fineness (dtex). The spinning speed was calculated from the average
single-fiber fineness and the rate of resin discharged from the
spinneret single hole (hereinafter referred to as "single-hole
discharge rate") (g/min) set under each set of conditions, using
the following equation
Spinning speed (m/min)=(10,000.times.[single-hole discharge rate
(g/min)])/[average single-fiber fineness (dtex)].
[0085] (5) Kinetic Friction Coefficient Between Spun-Bonded
Nonwoven Fabric's Fibers:
[0086] The friction coefficient between the fibers constituting the
spun-bonded nonwoven fabric was measured in accordance with JIS
L1015: 2010. The fibers were collected from the spun-bonded
nonwoven fabric, the fibers were wound in a cylinder having an
outer diameter of 8 mm of a radar type friction coefficient tester
so that the fibers were parallel to the axis of the cylinder.
Initial loads were put in both ends of the fibers, and the fibers
were hanged in the center of the cylindrical sliver, and one end
thereof is connected to a torsion balance hook. The cylindrical
sliver was rotated at a circumferential speed of 90 cm/min, a load
at which both ends of the fibers were balanced by the torsion
balance was determined, and the kinetic friction coefficient was
calculated by the following equation. For the fibers collected from
any three different places, the kinetic friction coefficients were
measured and an average thereof was determined as the kinetic
friction coefficient.
Kinetic friction coefficient (.mu.d)=0.733 log(W/(W-m)) [0087]
wherein, [0088] W: Load applied to both ends of fibers, [0089] m:
Torsion balance reading.
[0090] (6) Basis Weight of Spun-Bonded Nonwoven Fabric:
[0091] In accordance with JIS L1913 (year 2010), 6.2 "Mass per unit
area", three test pieces having a size of 20 cm.times.25 cm were
cut out per the sample width of 1 m and were each examined for
normal-state mass (g), and an average of the basis weight of the
spun-bonded nonwoven fabric was converted to mass per m.sup.2
(g/m.sup.2).
[0092] (7) Apparent Density of Spun-Bonded Nonwoven Fabric:
[0093] In accordance with 5.1 of JIS L1906 (year 2000 edition),
thicknesses (mm) at 10 points per meter of the spun-bonded nonwoven
fabric were measured in an unit of 0.01 mm at equal intervals in
the width direction of the nonwoven fabric at a load of 10 kPa by
using a pressure element having a diameter of 10 mm, and an average
value thereof was rounded off to two decimal places.
[0094] Subsequently, the apparent density (g/cm.sup.3) of the
spun-bonded nonwoven fabric was calculated based on the following
equation from the basis weight and the thickness before the
rounding off, and rounded off to two decimal places.
Apparent density (g/cm.sup.3)=[basis weight (g/m.sup.2)]/[thickness
(mm)].times.10.sup.-3
[0095] (8) Water Pressure Resistance per Unit Basis Weight of
Spun-Bonded Nonwoven Fabric:
[0096] The water pressure resistance of the spun-bonded nonwoven
fabric was measured in accordance with "7.1.1 A method (low water
pressure method)" in JIS L1092: 2009. Five test pieces of width of
150 mm.times.150 mm were collected at equal intervals in the width
direction of the spun-bonded nonwoven fabric, the test pieces were
set to a clamp (with a contact area of water to the test pieces of
100 cm.sup.2) by using an FX-3000-IV water pressure resistant
tester "hydro-tester" manufactured by Textest Co., Switzerland, a
water level was raised at a rate of 600 mm/min.+-.30 mm/min in a
leveling instrument with water, water was transmitted through the
test pieces, and the water level when water droplets were generated
at three places on the back side was measured in a unit of mm. The
measurement was performed with five test pieces, and an average
value thereof was set as the water pressure resistance (mm
H.sub.2O). The water pressure resistance thus determined was
divided by the basis weight before the rounding off based on the
following formula, and water pressure resistance per unit basis
weight (mmH.sub.2O/(g/m.sup.2)) was determined by being rounded off
to one decimal place.
Water pressure resistance per unit basis weight
(mmH.sub.2O/(g/m.sup.2))=[Water pressure resistance (mm
H.sub.2O)]/[basis weight (g/m.sup.2)]
[0097] (9) Maximum Pore Diameter and Average Pore Diameter of
Spun-Bonded Nonwoven Fabric:
[0098] The maximum pore diameter and the average pore diameter were
evaluated in accordance with JIS K 3832 (bubble point method) by a
porous material automatic fine pore measurement system "Capillary
Flow Porometer CPF-1500 AEXLC". A measurement sample has a diameter
of 25 mm, and fine pore diameter distribution measurement was
performed using Galwick (surface tension: 16 mN/m) as a measurement
liquid having a known surface tension. Air pressure was applied to
the nonwoven fabric completely immersed in the measurement liquid,
and the maximum pore diameter was calculated from pressure (bubble
point) when an appearance of air bubbles was observed. An average
value of the pore diameter was calculated from the pore diameter
distribution obtained from the measurement. In the measurement, any
five places per sample were sampled, and a value determined by
rounding off to the first decimal place of the average, and the
value with the first decimal place was used.
[0099] (10) Softness of Nonwoven Fabric (Moldability):
[0100] As a sensory evaluation of the sense of touch of the
nonwoven fabric, the softness was scored based on the following
criteria. The softness was scored by 10 persons and an average
thereof was evaluated as the sense of touch of the nonwoven fabric.
The higher the score is, the better the softness is, and thus
workability in various works was determined to be good, and the
softness of 4.0 points or higher was taken as pass.
<Softness (Moldability)>
[0101] 5 points: soft (good moldability) [0102] 4 points: between 5
points and 3 points [0103] 3 points: usual [0104] 2 points: between
3 points and 1 point [0105] 1 point: hard (poor moldability)
Example 1
[0106] A polypropylene resin made of a homopolymer having a melt
flow rate (MFR) of 200 g/10 min was melted with an extruder and
discharged from a rectangular spinneret having a spinning
temperature of 235.degree. C., a hole diameter .phi. of 0.30 mm,
and a hole depth of 2 mm at a single-hole discharge rate of 0.32
g/min. The resultant filaments were cooled and solidified by
blowing cold air with 13% variation in wind speed, subsequently
drawn and stretched by compressed air jetted from a rectangular
ejector at an ejector pressure of 0.35 MPa. A fiber spreading
device in which a flat plate having a width of 2 cm and a length of
10 cm facing right downward and a flat plate having a width of 2 cm
and a length of 10 cm inclined 10.degree. to 30.degree. on an
upstream side of the sheet flow direction were alternately arranged
in a comb-tooth shape at an ejector outlet was provided. The
filaments were dispersed and spread in the sheet flow direction
along the flat plates, and collected on a moving net. A nonwoven
fiber web composed of long polypropylene fibers was thus obtained.
The long polypropylene fibers obtained had the following
properties. The average single fiber diameter was 10.1 .mu.m, and
the spinning speed calculated therefrom was 4,400 m/min. With
respect to spinnability, no filament breakage occurred during
1-hour spinning, and the fibber had good spinnability.
[0107] Subsequently, a pair of embossing rolls composed of an upper
roll, which was a metallic embossing roll having polka dots formed
by engraving and having a proportion of bonding area of 16%, and a
lower roll, which was a metallic flat roll, was used to heat-bond
the obtained nonwoven fiber web at a linear pressure of 300 N/cm
and a heat-bonding temperature of 130.degree. C., and a spun-bonded
nonwoven fabric having a basis weight of 30 g/m.sup.2 was obtained.
The obtained spun-bonded nonwoven fabric was evaluated by measuring
the thickness, the apparent density, the maximum pore size, the
average pore size, the kinetic friction coefficient between the
fibers, the MFR of the fibers, and the water pressure resistance
per unit basis weight. The results thereof are shown in Table
1.
Example 2
[0108] A nonwoven fabric composed of long polypropylene fibers was
obtained by the same method as in Example 1, except that the
single-hole discharge rate was changed to 0.21 g/min, and the
ejector pressure was changed to 0.50 MPa. The spun-bonded long
fibers obtained had the following properties. The average single
fiber diameter was 7.2 .mu.m, and the spinning speed calculated
therefrom was 5,700 m/min. With respect to spinnability, no
filament breakage occurred during 1-hour spinning, and the fiber
had good spinnability. The results thereof are shown in Table
1.
Example 3
[0109] A nonwoven fabric composed of long polypropylene fibers was
obtained by the same method as in Example 1, except that the
ejector pressure was changed to 0.50 MPa. The spun-bonded long
fibers obtained had the following properties. The average single
fiber diameter was 8.9 .mu.m, and the spinning speed calculated
therefrom was 5,600 m/min. With respect to spinnability, no
filament breakage occurred during 1-hour spinning, and the fiber
had good spinnability. The results thereof are shown in Table
1.
Example 4
[0110] A spun-bonded nonwoven fabric was obtained by the same
method as in Example 1, except that 1.0% by mass ethylene
bisstearic acid amide was added as a fatty acid amide compound to
the polypropylene resin composed of a homopolymer. The results
thereof are shown in Table 1.
Example 5
[0111] A spun-bonded nonwoven fabric was obtained by the same
method as in Example 2, except that 1.0% by mass ethylene
bisstearic acid amide was added as a fatty acid amide compound to
the polypropylene resin composed of a homopolymer. The results
thereof are shown in Table 1.
Example 6
[0112] A spun-bonded nonwoven fabric was obtained by the same
method as in Example 3, except that 1.0% by mass ethylene
bisstearic acid amide was added as a fatty acid amide compound to
the polypropylene resin composed of a homopolymer. Results are
shown in Table 2.
Example 7
[0113] A spun-bonded nonwoven fabric composed of long polypropylene
fibers was obtained by the same method as in Example 1, except that
1.0% by mass of ethylene bisstearic acid amide was added as a fatty
acid amide compound to the polypropylene resin composed of a
homopolymer having an MFR of 60 g/10 min, and an ejector pressure
was 0.20 MPa. The spun-bonded long fibers obtained had the
following properties. The average single fiber diameter was 11.8
.mu.m, and the spinning speed calculated therefrom was 3,200 m/min.
With respect to spinnability, no filament breakage occurred during
1-hour spinning, and the fiber had good spinnability. Results are
shown in Table 2.
Comparative Example 1
[0114] A spun-bonded nonwoven fabric was obtained by the same
method as in Example 7, except that 1.0% by mass ethylene
bisstearic acid amide was not added as a fatty acid amide compound.
Results are shown in Table 2.
Comparative Example 2
[0115] A spun-bonded nonwoven fabric was obtained by the same
method as in Comparative Example 1, except that the ejector
pressure was changed to 0.15 MPa by using the polypropylene resin
composed of a homopolymer having an MFR of 35 g/10 min. Results are
shown in Table 2.
TABLE-US-00001 TABLE 1 Unit Example 1 Example 2 Example 3 Example 4
Example 5 Raw material Type of resin -- PP PP PP PP PP MFR of resin
g/10 min 200 200 200 200 200 Fatty acid amide compound -- -- -- --
Ethylene bisstearic Ethylene bisstearic acid amide acid amide Fiber
Average single fiber diameter .mu.m 10.1 7.2 8.9 10.1 7.2 Melt flow
rate g/10 min 210 210 210 210 210 Spinning speed m/min 4400 5700
5600 4400 5700 Single fiber CV % 4.2 3.4 3.4 3.5 2.8 Coefficient of
friction between fibers -- 0.28 0.27 0.27 0.23 0.21 Nonwoven Basis
weight g/m.sup.2 30 30 30 30 30 fabric Thickness mm 0.2 0.2 0.2 0.2
0.2 Apparent density g/cm.sup.3 0.150 0.150 0.150 0.150 0.150 Water
pressure resistance mm H.sub.2O 248 346 290 256 366 Water pressure
resistance per unit mm H.sub.2O/(g/m.sup.2) 8.3 11.5 9.7 8.5 12.2
basis weight Maximum pore diameter .mu.m 30 16 24 28 13 Average
pore diameter .mu.m 20 13 17 19 9 Softness and moldability of Point
4.1 4.5 4.3 4.2 4.8 nonwoven fabric
TABLE-US-00002 TABLE 2 Comparative Comparative Unit Example 6
Example 7 Example 1 Example 2 Raw material Type of resin -- PP PP
PP PP MFR of resin g/10 min 200 60 60 35 Fatty acid amide compound
-- Ethylene bisstearic Ethylene bisstearic -- -- acid amide acid
amide Fiber Average single fiber diameter .mu.m 8.9 11.8 11.8 14.5
Melt flow rate g/10 min 210 65 65 38 Spinning speed m/min 5600 3200
3200 2200 Single fiber CV % 3.3 6.2 6.2 7.1 Coefficient of friction
between fibers -- 0.22 0.24 0.30 0.32 Nonwoven Basis weight
g/m.sup.2 30 30 30 30 fabric Thickness mm 0.2 0.2 0.2 0.2 Apparent
density g/cm.sup.3 0.150 0.150 0.150 0.150 Water pressure
resistance mm H.sub.2O 302 212 188 150 Water pressure resistance
per unit mm H.sub.2O/(g/m.sup.2) 10.1 7.1 6.3 5.0 basis weight
Maximum pore diameter .mu.m 22 41 51 61 Average pore diameter .mu.m
15 24 28 33 Softness and moldability of Point 4.6 4.0 3.8 3.5
nonwoven fabric
[0116] The spun-bonded nonwoven fabrics of Examples 1 to 7 had the
average single fiber diameter of 6.5 to 11.9 .mu.m, the average
pore diameter of the nonwoven fabric surface of 0.1 to 25 .mu.m
since the single fiber CV was small and uniform. And they had the
maximum pore diameter of 50.mu.m or less, so that they had the
water pressure resistance per unit basis weight of 7
mmH.sub.2O/(g/m.sup.2) or more of excellent water resistance., And
the also had excellent softness and moldability. Particularly, in
Examples 4 to 6 in which ethylene bis-stearic acid amide was added,
because of a small friction coefficient between fibers, moderate
slipperiness at the time of collecting the fiber web was given.
Further, the average pore diameter on the nonwoven fabric surface
was 0.1 to 25 .mu.m, and the maximum pore diameter was 50 .mu.m or
less, so that the nonwoven fabrics had excellent water pressure
resistance per unit basis weight. These nonwoven fabrics were
suitable for use as a nonwoven fabric for building materials such
as a nonwoven fabric for house wrapping materials which are
required to have breathability and waterproofness.
[0117] Meanwhile, in Comparative Examples 1 and 2, since the
average pore diameter of the nonwoven fabric surface was larger
than 25 .mu.m and the maximum pore diameter was larger than 50
.mu.m, the water resistance was inferior.
[0118] Although the invention has been described in detail with
reference to the specific embodiments, it will be apparent to those
skilled in the art that various changes and modifications can be
made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application
2017-211607 filed on Nov. 1, 2017 and Japanese Patent Application
2018-141052 filed on Jul. 27, 2018, contents of which are
incorporated by reference herein.
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