U.S. patent application number 10/450413 was filed with the patent office on 2004-02-12 for melt-blown nonwoven fabric.
Invention is credited to Maki, Nobuyuki, Shimizu, Masaki, Suzuki, Hidefumi, Tachino, Hitoshi.
Application Number | 20040028878 10/450413 |
Document ID | / |
Family ID | 18856962 |
Filed Date | 2004-02-12 |
United States Patent
Application |
20040028878 |
Kind Code |
A1 |
Shimizu, Masaki ; et
al. |
February 12, 2004 |
Melt-blown nonwoven fabric
Abstract
A melt-blown nonwoven fabric of the present invention is formed
from an ethylene-(meth)acrylic acid copolymer having a melt flow
rate of 50 to 1000 g/10 min measured at 2.16 kg load and at a
temperature of 190.degree. C. in accordance with ASTM D1238, and a
content of acrylic acid or methacrylic acid unit of 2 to 25 weight
%. The nonwoven fabric has the sum of values of (tensile strength
(g/5 cm))/(basis weight (g/m.sup.2)) in machine direction and cross
direction of 30 to 100, and a residual strain after 50% extension
of no more than 20%, and is excellent in gas permeability ,
elasticity and moreover moderate strength. The nonwoven fabric is
suitable for elasticized fabric components, packaging materials,
laminates, etc.
Inventors: |
Shimizu, Masaki;
(Nagoya-shi, JP) ; Suzuki, Hidefumi;
(Yokkaichi-shi, JP) ; Tachino, Hitoshi;
(Ichihara-shi, JP) ; Maki, Nobuyuki;
(Ichihara-shi, JP) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
18856962 |
Appl. No.: |
10/450413 |
Filed: |
June 13, 2003 |
PCT Filed: |
December 21, 2001 |
PCT NO: |
PCT/JP01/11297 |
Current U.S.
Class: |
428/156 ;
264/210.2; 442/328; 442/400 |
Current CPC
Class: |
Y10T 442/601 20150401;
D04H 3/007 20130101; Y10T 442/68 20150401; D04H 3/16 20130101; Y10T
428/24479 20150115 |
Class at
Publication: |
428/156 ;
442/400; 442/328; 264/210.2 |
International
Class: |
D04H 001/00; D04H
001/56 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2000 |
JP |
2000-390637 |
Claims
1. A melt-blown nonwoven fabric formed from an
ethylene-(meth)acrylic acid copolymer.
2. The melt-blown nonwoven fabric of claim 1, wherein said ethylene
(meth)acrylic acid copolymer has a melt flow rate in the range of
from 50 to 1000 g/10 min, measured at 2.16 kg load at a temperature
of 190.degree. C. in accordance with ASTM D1238 and a content of
acrylic acid or methacrylic acid unit in the range of from 2 to 25
weight %.
3. The melt-blown nonwoven fabric of claim 1, wherein said ethylene
(meth)acrylic acid copolymers is blended with a thermoplastic
polymer selected from ethylene-.alpha.-olefin random copolymers,
ethylene-vinyl acetate copolymers, ethylene-(meth)acrylate
copolymers, styrene-conjugated diene-styrene block copolymers and
hydrogenated styrene-conjugated diene-styrene block copolymers.
4. The melt-blown nonwoven fabric of claim 1, wherein the sum of
values of (tensile strength (g/5 cm))/(basis weight (g/m.sup.2)) in
machine direction and cross direction is in the range of from 30 to
100, and each of tensile elongation in the machine direction and
the cross direction is 80% or more.
5. The melt-blown nonwoven fabric of claim 1, wherein a residual
strain after 50% extension is 20% or less, and a residual strain
after 100% extension is 50% or less.
6. The melt-blown nonwoven fabric of claim 1, wherein a basis
weight is in the range of from 5 to 200 g/m.sup.2.
7. The melt-blown nonwoven fabric of claim 1, wherein said
melt-blown nonwoven fabric is embossed.
8. An elasticized fabric component characterized by comprising a
melt-blown nonwoven fabric according to any one of claims 1 to
7.
9. A packaging material characterized by comprising a melt-blown
nonwoven fabric according to any one of claims 1 to 7.
10. A nonwoven fabric laminate characterized by comprising at least
one layer of a melt-blown nonwoven fabric according to any one of
claims 1 to 7.
11. A method of manufacturing the melt-blown nonwoven fabric of
claims 1 to 7, in which an ethylene-(meth)acrylic acid copolymer is
melted in an extruder, directly extruded from melt-blowing dies
located in a line into two flows of high-speed, high-temperature
converging air streams, and then the molten copolymer is drawn,
made finer and collected onto a conveying screen, wherein an amount
of air flow per one kilogram of said copolymer is in the range of
from 10 to 200 Nm.sup.3 and a distance from melt-blowing dies to a
collective screen is in the range of from 10 to 40 cm.
Description
TECHNICAL FIELD
[0001] The present invention relates to a melt-blown nonwoven
fabric, and particularly to a melt-blown nonwoven fabric suitable
for elasticized fabric components, packaging materials, laminates,
etc. having outstanding gas permeability, elasticity as well as
moderate strength.
BACKGROUND ART
[0002] In recent years, nonwoven fabrics have been used for various
kinds of applications, and their applications have also been
expanding. And demands for various characteristics are now
increasing in accordance with the uses. For example, excellent
elasticity with outstanding gas permeability is required, based on
the parts used, in nonwoven fabrics used for gathers of disposable
diapers, a part of medical supplies, such as sanitary napkins, base
cloths of wet compress, etc. Moreover, moderate strength is also
required in them upon their processing and molding processes.
[0003] Porous films of polyvinyl chroride are conventionally used
as materials such as poultice medicine base cloths etc. that are
attached to a human body using elasticity. However these materials
induce a problem of dioxin generation when they are wasted and
burned. Although polyurethane melt-blown nonwoven fabrics are
provided into market as a replacement of polyvinyl chloride, this
material is expensive and also has a problem of harmful gas
generation at the time of combustion.
[0004] For these reasons, a melt-blown nonwoven fabric that has a
moderate strength while having outstanding gas permeability and
elasticity and is made from a material with little environmental
burden has been required. A melt-blown nonwoven fabric excellent in
printability, low-temperature heat seal property and hot tack
property has also been required.
[0005] An objective of the present invention is to provide a
melt-blown nonwoven fabric that gives little burden on the
environment while having outstanding gas permeability and
elasticity as well as moderate strength, and that is comparatively
economical and advantageous in cost. Moreover, the other objective
of the present invention is to provide a melt-blown nonwoven fabric
excellent in printability, low-temperature heat. seal property and
hot tack property.
DISCLOSURE OF THE INVENTION
[0006] As a result of wholehearted examination made by the present
inventors in order to solve the above-mentioned problems, it was
found out that a melt-blown nonwoven fabric made from
ethylene-(meth)acrylic acid copolymers solves above described
problems, and the present invention was attained. In the present
invention, (meth)acrylic acid represents acrylic acid or
methacrylic acid, and ethylene-(meth)acrylic acid copolymers
represent ethylene-acrylic acid copolymers or ethylene-methacrylic
acid copolymers.
[0007] That is, according to the present invention, a melt-blown
nonwoven fabric made from ethylene-(meth)acrylic acid copolymers is
provided.
[0008] In a preferred embodiment of the above-mentioned
ethylene-(meth)acrylic acid copolymers, the copolymers preferably
have a melt flow rate of 50 to 1000 g/10 min measured at 2.16 kg
load and at a temperature of 190.degree. C. in accordance with ASTM
D1238, and 2 to 25 weight % of (meth)acrylic acid unit content.
[0009] In a preferred embodiment of the above-mentioned melt-blown
nonwoven fabric, the sum of values of tensile strength (g/5 cm)
/basis weight (g/m.sup.2) in machine direction and cross direction
is preferably 30 to 100, and tensile elongation in machine
direction and cross direction is 80% or higher each.
[0010] Moreover, in a preferred embodiment of the above-mentioned
melt-blown nonwoven fabric, a residual strain after 50% extension
is preferably 20% or less, and a residual strain after 100%
extension is no more than 50%.
[0011] An elasticized fabric component and packaging material
comprising the above-mentioned melt- blown nonwoven fabric, and a
nonwoven fabric laminate having at least one layer of the
above-mentioned melt-blown nonwoven fabric are provided by the
present invention.
[0012] A manufacturing method of the above-mentioned melt-blown
nonwoven fabric is preferably a melt-blowing method in which
ethylene-(meth)acrylic acid copolymer is directly extruded from
melt-blowing dies located in a line into two flows of high-speed,
high-temperature converging air streams , and then the molten
copolymer is drawn, made finer and collected onto a conveying
screen. In this process air flow per 1 kg of above-mentioned
copolymer is preferably 10 to 200 Nm.sup.3 and a distance from
melt-blowing dies to a collection screen is preferably 10 to 40
cm.
BEST MODE FOR CARRYING OUT THE INVENTION
[0013] A description about a melt-blown nonwoven fabric of the
present invention and its manufacturing method will concretely be
given hereinafter.
[0014] A melt-blown nonwoven fabric (henceforth, referred to as a
melt-blown nonwoven fabric of the present invention) of the present
invention is made from ethylene-(meth)acrylic acid copolymers.
[0015] The ethylene-(meth)acrylic acid copolymers are copolymers in
which ethylene is copolymerized with acrylic acid or methacrylic
acid and, if necessary, further unsaturated carboxylic acid esters
by a well-known radical polymerization method etc., and contain a
unit of acrylic acid or methacrylic acid of preferably 2 to 25
weight %, more preferably 5 to 20 weight %, and still more
preferably 10 to 15 weight % in a polymer. When a content of
acrylic acid or methacrylic acid unit is in this range, good touch
and flexibility as well as good elasticity, chemical resistance,
solvent resistance, hot tack property, heat seal property, and
printability, and also an advantage in cost are obtained. Moreover,
an extrusion temperature in the range of from 160 to 280.degree. C.
is suitable, and it has an advantage that the
ethylene-(meth)acrylic acid copolymers may be extruded at a higher
temperature(e.g. 240.degree. C. or more) than ethylene-vinyl
acetate copolymers.
[0016] Besides, if an unsaturated carboxylic acid ester unit exists
in the ethylene-(meth)acrylic acid copolymers, it improves
flexibility, and its content usually ranges 0 to 25 weight %, and
preferably 0 to 15 weight %, and more preferably 0 to 10 weight %.
As unsaturated carboxylic acid esters, alkyl esters with 1 to 8
carbons of (meth)acrylic acid are preferable, and, specifically,
methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl
methacrylate, iso-propyl acrylate, iso-propyl methacrylate, n-butyl
acrylate, n-butyl methacrylate, iso-butyl acrylate, iso-butyl
methacrylate, 2-ethylhexyl acrylate, and 2-ethylhexyl methacrylate
etc. may be mentioned.
[0017] Besides, a melt flow rate (MFR) of the
ethylene-(meth)acrylic acid copolymers, measured under the
conditions of 2.16 kg load at a temperature of 190.degree. C., in
accordance with ASTM D1238 is preferably 50 to 1000 g/10 min, more
preferably 100 to 500 g/10 min. If an MFR value is within the
range, a phenomonon of generating of scattering of fiber waste
(fly) and resin lump (shot) that often pose problems in
melt-blowing methods is hardly observed, and it becomes easy to
make fibers finer.
[0018] In the present invention in order to improve tensile
elongation of a melt-blown nonwoven fabric, thermoplastic polymers
selected from ethylene-a-olefin random copolymers, ethylene-vinyl
acetate copolymers, ethylene-(meth)acrylate copolymers,
styrene-conjugated diene-styrene block copolymers and hydrogenated
styrene-conjugated diene-styrene block copolymers may be blended to
ethylene-(meth)acrylic acid copolymers. These thermoplastic
polymers may be blended in an amount of 0 to 100 weight parts,
preferably 0 to 40 weight parts, more preferably 0 to 10 weight
parts to ethylene-(meth)acrylic acid copolymers of 100 weight
parts.
[0019] In the above-mentioned ethylene-a-olefin random copolymers,
it is preferable to use copolymers with a density of 870 to 940
kg/m.sup.3 and especially of 880 to 930 kg/m.sup.3. Besides, as
.alpha.-olefins in the copolymers, .alpha.-olefins with 3 to 12
carbons, such as propylene, 1-butene, 1-pentene, 1-hexene,
1-octene, 1-decene, 1-dodecene, and 4-methyl-1-pentene may be
mentioned. Such ethylene-.alpha.-olefin random copolymers may be
manufactured with single-site catalysts or with multi-site
catalysts.
[0020] As the above-mentioned ethylene-vinyl acetate copolymers,
vinyl acetate unit is preferably 5 to 40 weight %, and especially
preferably 10 to 30 weight %. Besides,. as the above-mentioned
ethylene-(meth)acrylate copolymers, (meth)acrylic acid ester unit
is preferably 5 to 40 weight %, and especially preferably 10 to 30
weight %. What is already mentioned may be used here as
(meth)acrylic acid esters. These copolymers may be obtained by a
radical copolymerization under a condition of high temperature and
high pressure.
[0021] As the above-mentioned ethylene-.alpha.-olefin copolymers,
ethylene-vinyl acetate copolymers and ethylene-(meth) acrylate
copolymers, an MFR based on 190.degree. C. and 2.16 kg load of 1 to
100 g/10 min are preferable, and that of 10 to 500 g/10 min are
more preferable.
[0022] As conjugated dienes in the above-mentioned
styrene-conjugated diene-styrene block copolymers, and hydrogenated
copolymers of them, butadiene or isoprene is preferable. Besides,
in styrene-conjugated diene-styrene block copolymers, conjugated
dienes are polymerized by 1,2-polymerization, 1,4-polymerization,
3,4-polymerization, or by polymerization in the combination of
these polymerizations. In the copolymers, a styrene unit preferably
accounts for the range of 8 to 50 weight %, especially 10 to 40
weight %. Besides, in the above-mentioned hydrogenated polymers,
conjugated diene units are preferably hydrogenated by 70% or more,
more preferably by 90% or more. As styrene-conjugated diene-styrene
block copolymers, and their hydrogenated copolymers, copolymers
that have an MFR at 230.degree. C. and 2.16 kg load of 1 to 200g/10
min are preferably used, and that have an MFR of 2 to 100 g/10 min
are more preferably used.
[0023] In the present invention, other resins may be added to the
above-mentioned ethylene-(meth)acrylic acid copolymers and the
above-mentioned thermoplastic polymers needed to be blended, in a
range in which the objectives of the present invention are not
impaired. As other resins that may be added, for example;
polyethylenes (high pressure low density polyethylenes, middle or
high-density polyethylenes, etc.), polypropylenes (homopolymers,
random copolymers and block copolymers with other a-olefins),
polyethylene terephthalates, polyester elastomers, polyamides
(nylon), polyurethanes, polyvinyl alcohol, ethylene-(meth)acrylic
acid copolymer ionomers, and polystyrenes etc. may be
mentioned.
[0024] In the present invention, pigments, heat stabilizers,
lubricants, nuclear agents, etc. may be blended into the
above-mentioned ethylene-(meth)acrylic acid copolymers in a range
in which the objective of the present invention are not
impaired.
[0025] A melt-blown nonwoven fabric made from the above-mentioned
ethylene-(meth)acrylic acid copolymers can be made by a
conventional melt-blowing method where ethylene-(meth)acrylic acid
copolymer is directly extruded from melt-blowing dies located in a
line into two flows of high-speed, high-temperature converging air
streams and then the molten copolymer is drawn, made finer and
collected onto a conveying screen.
[0026] In this case, air flow per 1 kg of the above-mentioned
copolymer is 10 to 200 Nm.sup.3 and more preferably 20 to 150
Nm.sup.3. If the amount of air flow in this range is used, the
diameter of fiber becomes moderately small and an aggravation of
physical properties does not happen. In addition, a fly phenomenon
that often occurs when air flow is excessive is not observed, and
troubles in production may be avoided.
[0027] Moreover, the distance from the melt-blowing dies to the
collective screen is preferably 10 to 40 cm, and more preferably 15
to 25 cm. If this distance is within this range, a surface of
nonwoven fabric becomes smooth, and a poor appearance caused by
fiber bundles is avoidable. Moreover, tensile strength reaches a
satisfactory level.
[0028] Furthermore, a nonwoven fabric web formed by the
melt-blowing method is preferably thermal-bonded in parts by emboss
processing. When emboss processing is carried with the embossed
part in perfect molten state, a thermal-bonded area (equivalent to
stamping area of the embossing roll) is preferably 1 to 50% of the
overall nonwoven fabric area, and when emboss processing is carried
out with the embossed part in half-molten state (to maintain fiber
shape), a thermal-bonded area is preferably 10 to 100% of the
overall nonwoven fabric area. If a percentage of thermal-bonded
area is in this range, soft touch of melt-blown nonwoven fabric is
maintained and tensile strength and abrasion resistance are
improved.
[0029] A basis weight of a melt-blown nonwoven fabric of the
present invention obtained as mentioned above is preferably 5 to
200 g/m.sup.2, and more preferably 30 to 100 g/m.sup.2. Moreover,
an average diameter of fiber of a melt-blown nonwoven fabric is
preferably 5 to 20 micrometers.
[0030] A description about tensile characteristics of a melt-blown
nonwoven fabric of the present invention is given below.
[0031] The sum of values of (tensile strength)/(basis weight)
obtained by dividing tensile strength (g/5 cm) by basis weight
(g/m.sup.2) of nonwoven fabric in machine direction and in cross
direction is preferably 30 to 100, more preferably 50 to 100.
[0032] Tensile elongation in each of machine direction and cross
direction is preferably 80% or more, and more preferably 100% or
more.
[0033] In the present invention, "machine direction (MD)" means a
direction of flow of nonwoven fabric in nonwoven fabric fabricating
operation, and "cross direction (CD)" means a transverse direction
in the direction of the flow of the nonwoven fabric.
[0034] Moreover, in machine direction and cross direction, a
residual strain after 50% extension is preferably 20% or less, more
preferably 15% or less, and a residual strain after 100% extension
is preferably 50% or less, and more preferably 35% or less. A
residual strain after extension here means a percentage of a length
of a sample extended to an original length of the sample, in which
a nonwoven fabric sample is elongated to a predetermined elongation
and immediately returned to the original position at the same
elongation/shrinking speeds.
[0035] Since a melt-blown nonwoven fabric of the present invention
has such tensile characteristics as well as excellent elasticity
and gas permeability, and moderate strength, it is extremely
excellent as a nonwoven fabric for elasticized fabric components,
and can be used as a base cloth for plasters, wet compress and
poultice medicines etc.; body personal protective equipments such
as supporters, sacks, and bandages; elastic components for surgical
goods of masks, caps, shoes covers, etc.; elastic components for
health goods of disposable diapers, sanitary napkins, etc. A
melt-blown nonwoven fabric of the present invention may also be
used as packaging materials such as; for example, gas permeable
packaging materials for insecticides/fungicides,
deodorants/odorants, oxygen absorbents, chemical body warmers,
perfumes, sweets, and fruits; packaging materials for medical goods
(syringes etc.) sterilizable with glycerol; or water permeable
packaging materials for tea, green tea, coffee, agricultural
chemicals, water pigment, and ink.
[0036] Furthermore, since a melt-blown nonwoven fabric of the
present invention has flexibility, good chemical resistance,
solvent resistance, and touch, moderate strength and an outstanding
printability, it may suitably be used as a nonwoven fabric laminate
that has at least one layer of the melt-blown nonwoven fabrics.
Specifically, the laminates can be used for disposable garments
(under wears, work wears, surgical gowns and masks), and interior
materials for curtains and tablecloths. In such laminates, various
films, textiles, nonwoven fabrics, cotton cloths, nets, tallies,
synthetic paper, etc. may be selected as materials to make
laminates with a melt-blown nonwoven fabric of the present
invention.
[0037] Specifically, they are films of thermoplastic polymers such
as olefin polymers like polyethylene, polypropylene,
poly-4-methyl-1-pentene- , ethylene-vinyl acetate copolymers, or
polyesters and polyamides, and textiles, nonwoven fabrics, cotton
cloths, nets, tallies, synthetic paper, etc. which are comprised
from fibers of above-mentioned thermoplastic polymers, regenerated
fibers and/or natural fibers. The above-mentioned films may or may
not be oriented, and moreover, may be non-porous films or porous
films. Moreover, the above-mentioned nonwoven fabric obtained by
various methods may be used. For example, a nonwoven fabric
manufactured by methods, such as spun-bonding method, melt-blowing
method, dry process method, and wet process method, may be
used.
EXAMPLES
[0038] Hereinafter, although a description of the present invention
is given in detail by referring to Examples, the present invention
is not limited to these Examples.
[0039] Measurements of a ratio of (tensile strength)/(basis
weight), tensile elongation, a residual strain after extension, and
the diameter of a fiber, evaluations of appearance, touch, strength
of hot tack and heat seal strength in the following Examples were
performed according to the following methods.
[0040] (1) (Tensile Strength)/(Basis Weight) and Tensile
Elongation
[0041] A nonwoven fabric specimen with a width of 5 cm was held in
100 mm of distance between chucks of a tension tester and tensile
test was performed under a condition of elongation speed of 100
mm/min at room temperature. Maximum strength (g) obtained by this
test was defined as tensile strength (g/5 cm), and maximum
elongation was defined as tensile elongation. Measurement was
performed in two directions of machine direction (MD) and cross
direction (CD). A value of tensile strength in each direction was
divided by basis weight (g/m.sup.2) of nonwoven fabric specimen and
a value of (tensile strength)/(basis weight) was calculated.
[0042] (2) Residual Strain after Extension
[0043] A nonwoven fabric specimen with a width of 5 cm was held in
100 mm of distance between chucks of the tension tester as
described in the tensile test, under a condition of elongation
speed of 100 mm/min at room temperature. The specimen was elongated
up to 50% or 100%, and then returned at the same
elongation/shrinking speed to a point where the stress reached 0.
The percentage of a length of the specimen elongated and that of
relaxed was defined as a residual strain. Measurement was performed
in two directions of machine direction (MD) and cross direction
(CD).
[0044] (3) Diameter of a Fiber
[0045] The diameter of fiber was an average of 30 fibers selected
at random where each measurement was done using photographs of
.times.500 magnification by an electron microscope.
[0046] (4) Appearance
[0047] Visual observation of the nonwoven fabric was carried out,
and existence of fiber bundle was evaluated. A mark of
.largecircle. was given when no fiber bundle was observed, and x
was given when fiber bundle was clearly observed.
[0048] (5) Touch
[0049] A sensory evaluation by 10 panels was performed. Nonwoven
fabric sample was touched to skin of evaluators, and the skin was
rubbed lightly with the sample. A mark of .largecircle. was given
when seven or more panels judged that the sample had a smooth touch
and no coarse touch, and x was given when other evaluation was
given.
[0050] (6) Hot-Tack Strength
[0051] After a sample was heat sealed with heat seal pressure of
0.28 MPa and for heat seal time of one second, hot-tack strength
was determined as the peel strength at a rate of 1000 mm/min after
0.375 seconds of the one second heat seal.
[0052] (7) Heat Seal Strength
[0053] After a sample was heat sealed by one side heating with heat
seal pressure of 0.2 MPa and for heat seal time of 2 seconds, heat
seal strength was determined as the peel strength at a rate of 300
mm/min.
EXAMPLE 1
[0054] An ethylene-methacrylic acid copolymer (MFR: 100 g/10 min,
measured at 2.16 kg load and at temperature of 190.degree. C. based
on ASTM D1238 (the following MFR measurement uses the same
conditions), methacrylic acid unit content: 11 weight %) was melted
in an extruder at an extrusion temperature of 250.degree. C. The
obtained molten material was extruded into high-speed,
high-temperature air stream through melt-blowing dies, and
collected on a collecting screen, and thus a melt-blown nonwoven
fabric of 13 micrometers in diameter of a fiber and a basis weight
of 40 g/m.sup.2 was manufactured. At this time, an amount of air
flow per 1 kg of above-mentioned copolymer was 65 Nm.sup.3, and the
distance (collection distance) from the melt-blowing dies to the
collection screen was 25 cm.
[0055] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 1.
EXAMPLE 2
[0056] A melt-blown nonwoven fabric of 12 micrometers in diameter
of a fiber and a basis weight of 40 g/m.sup.2 was manufactured as
in Example 1 except the change of the amount of air flow per 1 kg
of copolymer to 120 Nm.sup.3.
[0057] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 1.
EXAMPLE 3
[0058] An ethylene-methacrylicacidcopolymer (MFR: 300 g/10 min,
methacrylic acid unit content: 20 weight %) was melted in the
extruder at an extrusion temperature of 190.degree. C. Obtained
molten material was extruded into high-speed, high-temperature air
stream through the melt-blowing dies, and collected on the
collecting screen, and thus a melt-blown nonwoven fabric of 8
micrometers in diameter of a fiber and a basis weight of 40
g/m.sup.2 was manufactured. At this time, the amount of air flow
per 1 kg of above-mentioned copolymer was 120 Nm.sup.3, and the
distance (collection distance) from the melt-blowing dies to the
collection screen was 25 cm.
[0059] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 1.
EXAMPLE 4
[0060] An ethylene-methacrylic acid copolymer (MFR: 500 g/10
minutes, methacrylic acid unit content: 20 weight %) was melted in
the extruder at an extrusion temperature of 170.degree. C. The
molten material obtained was extruded into high-speed,
high-temperature air stream through the melt-blowing dies, and
collected on the collecting screen, and thus a melt-blown nonwoven
fabric of 7 micrometers in diameter of fiber and a basis weight of
40 g/m.sup.2 was manufactured. At this time, the amount of air flow
per 1 kg of above-mentioned copolymer was 120 Nm.sup.3, and the
distance (collection distance) from the melt-blowing dies to the
collection screen was 25 cm.
[0061] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 1.
REFERENTIAL EXAMPLE 1
[0062] A melt-blown nonwoven fabric of 7 micrometers in diameter of
a fiber and a basis weight of 40 g/m.sup.2 was manufactured as in
Example 4 except the change of the amount of air flow per 1 kg of
copolymer to 200 Nm.sup.3, and the change of the collection
distance to 45 cm.
[0063] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 1.
1 TABLE 1 Referential Example Example 1 2 3 4 1 Tensile (MD/ 60/24
50/22 57/25 58/22 20/15 strength/ CD) basis (MD + 84 72 82 80 35
weight CD) Tensile elongation 125/150 116/106 133/175 120/165 55/63
(MD/CD) % Residual strain after 11/11 13/15 11/11 12/11 68/52 50%
extension (MD/CD) % Residual strain after 27/27 35/32 28/26 32/28
fractured 100% extension (MD/CD) % Appearance .smallcircle.
.smallcircle. .smallcircle. .smallcircle. x Touch .smallcircle.
.smallcircle. .smallcircle. .smallcircle. .smallcircle.
EXAMPLE 5
[0064] The melt-blown nonwoven fabric (basis weight 40 g/m.sup.2)
made from ethylene-methacrylic acid copolymer in Example 1 was
adhered to commercially available OPP film (biaxially oriented
polypropylene film, thickness of 20 micrometers) by a polyurethane
adhesive. Hot tack and heat seal strength of the nonwoven fabric
face were measured. Results are shown in Table 2 and 3,
respectively. As shown in Tables, the melt-blown nonwoven fabric of
ethylene-methacrylic acid copolymer obtained exhibits an
outstanding hot tack property and low-temperature heat seal
property, and therefore, is useful as an inner layer of packaging
bags which are heat sealed.
COMPARATIVE EXAMPLES 1, 2
[0065] The melt-blown nonwoven fabric (basis weight 40 g/m.sup.2)
made from ethylene-methacrylic acid copolymer in Example 5 was
replaced with a polypropylene melt-blown nonwoven fabric (Mitsui
Chemicals Co., LTD. SYNTEX V3040 NIE) of basis weight 40 g/m.sup.2,
or a polypropylene spun-bonded nonwoven fabric. (Mitsui Chemicals
SYNTEX PS-108) of basis weight 40 g/m.sup.2, and the two fabrics
were adhered onto an OPP film as in Example 5. Hot tack and heat
seal strength of each nonwoven fabric face were measured. Results
are shown in Table 2 and Table 3, respectively.
[0066] As shown in Tables, the melt-blown nonwoven fabric of
polypropylene and the spun-bonded nonwoven fabric of polypropylene
are inferior to the melt-blown nonwoven fabric of
ethylene-methacrylic acid copolymer, as an inner layer of packaging
bags to be heat sealed.
2 TABLE 2 Measurement Hot tack strength (N/25 mm) temperature
Comparative Comparative (.degree. C.) Example 5 Example 1 Example 2
90 1.2 below 0.1 below 0.1 100 1.4 below 0.1 below 0.1 110 1.1
below 0.1 below 0.1 120 0.9 below 0.1 below 0.1 140 -- 0.2 below
0.1 150 -- 0.1 below 0.1 160 0.1 below 0.1 below 0.1
[0067]
3 TABLE 3 Measurement Heat seal strength (N/25 mm) temperature
Comparative Comparative (.degree. C.) Example 5 Example 1 Example 2
90 1.80 not adhered not adhered 100 5.15 not adhered not adhered
110 7.95 not adhered not adhered 120 8.75 not adhered not adhered
140 -- 0.65 not adhered 150 -- 1.25 not adhered 160 0.1 0.95
9.55
EXAMPLE 6
[0068] A melt-blown nonwoven fabric (MB) of ethylene-methacrylic
acid copolymer (10 g/m.sup.2) was prepared as in Example 1, except
the change of the amount of air flow per 1 kg of copolymer to 150
Nm.sup.3, and a basis weight is adjusted to 10 g/m.sup.2 in Example
1. This melt-blown nonwoven fabric was laminated with a spun-bonded
nonwoven fabric (PE SB) made from polyethylene of basis weight of
30 g m.sup.2 (STRAMIGHTY MN made by Idemitsu Petrochemical Co.,
LTD) by an embossing roll at 70.degree. C. Evaluation of touch of
the face of the ethylene-methacrylic acid copolymer melt-blown
nonwoven fabric in this laminate was performed. Result is shown in
Table 4. Moreover, surface tension of this nonwoven fabric face was
measured in order to determine printing characteristics. The result
is also shown in Table 4.
[0069] These evaluations show that a nonwoven fabric of being
excellent in touch, wettability, and printability may be obtained
by the use of melt-blown nonwoven fabric made from
ethylene-methacrylic acid copolymer in one layer of nonwoven fabric
laminates.
COMPARATIVE EXAMPLES 3 and 4
[0070] Results of evaluation of touch and surface tension for a
spun-bonded nonwoven fabric (PE SB) made from polyethylene of basis
weight 30 g/m.sup.2 (STRAMIGHTY MN made by Idemitsu Petrochemical
Co., LTD), and a propylene spun-bonded nonwoven fabric (PP MB)
(Mitsui Chemicals Co., LTD. SYNTEX PS- 108) of basis weight 40
g/m.sup.2 are shown in Table 4.
4 TABLE 4 Surface tension Nonwoven fabric Touch (mN/m) Example 6
Copolymer MB/PE SB .smallcircle. 41 laminated Comparative PE SB
(spun-bonded) x 34 example 3 Comparative PP MB (melt-blown) x 32
example 4
EXAMPLE 7
[0071] Ethylene-1-butene random copolymer (Mitsui Chemicals, Inc.
Tafmer A70090, density 890 kg/m.sup.3) 20 weight % was dry blended
with ethylene-methacrylic acid copolymer (MFR: 500 g/10 min,
methacrylic acid unit content: 10 weight %) 80 weight %, and melt
blended in an extruder. The molten mixture obtained was extruded
into high-speed , high-temperature air stream from the melt-blowing
dies, and collected on the screen to manufacture a melt-blown
nonwoven fabric of 12 micrometers in diameter of a fiber and a
basis weight of 40 g/m.sup.2. At this time, the amount of air flow
per 1 kg of the resin was 27 Nm.sup.3, and the distance from the
melt-blowing dies to the collection screen 15 was 15 cm.
[0072] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 5.
EXAMPLE 8
[0073] A melt-blown nonwoven fabric with 13 micrometers in diameter
of a fiber and a basis weight of 40 g/m.sup.2 was manufactured by
the same method as Example 7, except the change of using the
ethylene-methacrylic acid copolymer of Example 7 by 80 weight %,
and a hydrogenated styrene-butadiene-styrene block copolymer (Asahi
Kasei Corporation, Tuftec H1031) by 20weight %, and the change of
the amount of spinning air flow to 44 Nm.sup.3 per 1 kg of the
blend. Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 5.
EXAMPLE 9
[0074] A melt-blown nonwoven fabric with 10 micrometers in diameter
of a fiber and a basis weight of 40 g m.sup.2 was manufactured by
the same method as Example 7, except the change of using 80 weight
% of the ethylene-methacrylic acid copolymer of Example 7 and 20
weight % of an ethylene-vinyl acetate copolymer (Du Pont-Mitsui
Polychemicals Co., Ltd., EVAFLEX V577), and the change of the
amount of spinning air flow to 15 Nm.sup.3 per 1 kg of the
blend.
[0075] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 5.
EXAMPLE 10
[0076] A melt-blown nonwoven fabric with 11 micrometers in diameter
of a fiber and a basis weight of 40 g/m.sup.2 was manufactured by
the same method as Example 7, except the change of using 80 weight
% of the ethylene-methacrylic acid copolymer of Example 7, and 20
weight % of an ethylene-ethyl acrylate copolymer (MFR: 275 g/10
min, ethyl acrylate unit content: 25 weight %) , and the change of
the amount of spinning air flow to 27 Nm.sup.3 per 1 kg of the
blend.
[0077] Measurement and evaluation results of the obtained
melt-blown nonwoven fabric are shown in Table 5.
5 TABLE 5 Example 7 8 9 10 Tensile (MD/ 23/17 23/19 21/16 21/17
strength/ CD) basis (MD + 40 42 37 38 weight CD) Tensile elongation
205/220 380/400 210/200 200/205 (MD/CD) % Residual strain after
100% extension 28/28 28/26 30/30 28/28 (MD/CD) %
[0078] Industrial Applicability
[0079] Since a melt-blown nonwoven fabric of the present invention
is excellent in elasticity, gas permeability and moderate strength,
it is excellent as nonwoven fabric for elasticized fabric
components, and can preferably be applicable for base cloths for
adhesive bandages, fomentation poultice; supporters, sacks,
bandages; surgical masks, caps, shoe covers; disposable diapers,
sanitary napkins, etc. A melt-blown nonwoven fabric of the present
invention can also be applicable for packaging materials and
nonwoven fabric laminates.
[0080] Moreover, a melt-blown nonwoven fabric of the present
invention does not usually cause a problem of harmful gas
generation when it is wasted and burned, and therefore, has little
burden on the environment.
* * * * *