Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a novel bulky nonwoven fabric
formed by an orderly arrangement of ~ibersO
Many kinds of nonwoven fabrics have hitherto been
developed, and are widely used for various applications.
There are, thus, various types of nonwoven fabrics, and
various methods of making the sa~e, including those known under
the name of the melt blowing method (Japanese Patent Application
Laid-Open Specification No. 10258/1974), the melt-blow molding
method (Japanese Patent Application Laid-Open Specification
No. 46972/1975), the jet spinning method (Japanese Patent
Publication No. 25871/1969), or the like. According to these
methods, a thermoplastic resin is melt-spun, and blown in the
form of fine fibers against a moving collector by a high-speed
flow of a gas.
A study has recently come to be made about the use
of the nonwoven fabrics obtained by these~methods for making
filter materials, carpets, synthetic leathers, or the like.
However, the nonwoven fabrics prepared by any such method
lack uniformity in thickness and basis weight, and are not
bulky since, the fibers lie parallel to the fabric surfaces
(i~e., two-dimensionally). These prior art products present
various obstacles to the preparation of satisfactory products
as intended, and no satisfactory carpet, leather or the like
has yet been prepared from the nonwoven fabrics available in
the art.
It is an object of this invention to provide a non-
woven fabric having a novel structure which eliminates the
drawbacks of the nonwoven fabrics known in the art. This
invention consists essentially in a melt blown nonwoven fabric
comprising stacked and intertwined long fibers ~orming thin
intertwined layers extending between one surface of said fabric
or part thereof and another surface of said fabric or part
thereof.
In the drawings:
FIGURE 1 is a view schematically showing a nonwoven
fabric embodying this invention.
FIGURE 2 is a view similar to FIGURE 1 showing a
-- 1 --
~ ~ 6~
-
--2--
1 nonwoven fabric known in the art;
2 FIGURE 3 is a perspective view generally showing
3 the nonwoven fabric of this invention;
4 FIGVRE 4 to 7 illustrate various forms of the non-
woven fabric of this invention at plane A in FIGURE l;
6 FIGURE 8 is a detailed view illustrating a method
7 of manufacturing the nonwoven fabric according to this in-
8 vention.
9 FIGURES 9 and 10 are views describing the apertures
with which the side wall of the drum 81 supporting the col-
11 lector 8 shown in FIGURE 8 is pierced; and
12 FIGURE 11 iS a view describing the process in which
13 the nonwoven fabric is formed by the method shown in FIGURE
14 8.
The nonwoven fabric of this invention will now be
16 described with reference to the drawings. In FIGURE 1, nu-
17 merals 2 and 2' denote the opposite surfaces of the nonwoven
18 fabric 1, letter A indicates one cross-sectional plane ex-
19 tending between the surface 2 or a part thereof, and the
surface 2' or a part thereof (which for the sake of conven-
21 ience will hereinafter be called the longitudinal sectional
22 plane), and letter B indicates another cross-sectional plane
23 extending between the surface 2 or a part thereof~ and the
24 surface 2' or a part thereof (which will hereinafter be
called the transverse sectional plane)7 Numeral 3 denotes
26 an intermediate fibrous layer disposed between the surfaces
27 2 and 2', and composed of a plurality of long fibers which
28 are intertwined and stacked together. Numerals 4, 4', 4"
29 indicate thin layers each composed of intertwined long fi-
bers. The thin layers 4, 4', 4", are actually continuously
31 combined with one another, and cannot be distinquished from
32 one another as clearly as shown in FIGURE 1, which is a
33 schematic view provided for the convenience of illustration.
34 However, as it is possible to divide the fabric into such
layers, each having a desired thickness, FIGURE 1 shows the
36 fabric as if it were composed of clearly distinguishable
37 layers.
--3--
1 FIGURE 1 shows the thin layers 4, 4', ~", which co-
2 operate with one another to define the surfaces ~ and 2' of
3 the nonwoven fabric 1. This feature makes the nonwoven
4 fabric of this invention comp:Letely different from any known
nonwoven fabric having such thin layers 104, 104' 104" lying
6 substantially in parallel to its surfaces 102 and 102' as
7 shown in FIGURE 2.
8 The thin layers 4, 4', 4" shown in FIGURE 1 are each
9 formed by a plurality of long fibers intertwined and col-
lected on the surfaces. In other words, the thin layers
11 are of the same construction as in the nonwoven fabrics
12 known in the art. Accordingly, the nonwoven fabric of this
13 invention is characterized by the single fibers lying to-
14 gether along the thickness of the fabric. The single fibers
forming each of the thin layers are intertwined, and con-
16 nected to the surfaces 2 and 2' to define them.
17 The structure of the nonwoven fabric according to
18 this invention has been schematically shown in FIGURE 1.
lg FIGURES 3 to 7 show embodiments of the nonwoven fabric of
the invention. FIGURES 4 to 7 illustrate the plane A of
21 FIGURE 1. FIGURES 3 to 6 show the surfaces 2 and 2' de~ined
22 by surface layers composed of a multiplicity of fibers;
23 FI~URE 7 shows the surface 2 formed by long fibers exposed
24 from the fibrous layer 3 per se. The nonwoven fabric of the
type shown in FIGURE 7 may also be prepared if a nonwoven
26 fabric of the type as shown in FIGURES 3 to 6 is cut along
27 any longitudinal plane lying between the surfaces 2 and 2'
28 in parallel thereto.
29 The nonwoven fabric of this invention constructed as
hereinabove described usually has a thickness of about 0.5
31 to about 100 mm, and a basis weight of about 5 to about
32 2,000 g/m2. It is preferably prepared from very fine fibers
33 having a diameter usually in the range of about 0.1 to about
34 30 ~, prefe:rably in the range of about 1 to about 20 ~ and
more preferably in the range of about 2 to about 10 ~.
36 Although the nonwoven fabric of this invention can
37 be made of any material without any limitation in particu-
V~l~
lar, it is desirable to prepare it from a thermoplastic resin.
Examples of the thermoplastic resin which can be used include
polyolefins such as homopolymers of ethylene, propylene,
butene-l, 4-methylpentene-1, or other ~-olefins, copolymers
thereof, and the mixtures of those polymers, polyamides such
as nylon 6, nylon 66, nylon 612, nylon 12 (trade or common
names), and their mixtures, polyesters such as polyethylene
terephthalate, polybutylene terephthalate, and polyurethane,
particularly thermoplastic polyurethane, ethylene~vinyl acetate
copolymers, ethylene-methacrylic acid ester copolymers, and
graft copolymers of polyolefins with unsaturated carboxylic
acids or their derivatives. It is also possible to use any
mixture of those thermoplastic resins.
The nonwoven fabric of this invention may be manufac-
tured by various melt blown methods. It is possible to prepare
the surface layer 2 and the fibrous layer 3 separately, and
combine them together, but it is more desirable to form them as
an integral assembly in a single stage of operation. A pre-
ferred method for making the nonwoven fabric according to this
invention will be described hereunder by way of example.
Referring to FIGURE ~ which illustrates a melt blowing
process, a thermoplastic substance is fed into an extruder 5
through its hopper 11, and melted under heat in the extruder 5.
The molten substance is fed through a die 6 provided on the
extruder 5, and is continuously spun through spinning holes 61
in the die 6. The die 6 is provided on both sides of its
spinning holes 61 adjacent thereto with gas emitting ports 62,
and gas feeding tubes 63 for supplying a gas into the gas emit-
ting ports 62. A high pressure gas supplied through the gas
feeding tubes 63 is blown out through the gas emitting ports 62
at a speed which is close to that of sound. The thermoplastic
substance spun through the spinning holes 61 is divided into
fine fibers by the gas discharged through the gas emitting
holes 62 at such a high speed, thereby forming a stream of
fibers 7 with the gas. If required, a liquid drop supply-
~ - 4 -
1 ing unit 10 is provided for supplying liquid drops toward
2 the fiber stream 7. After the fiber stream 7 is contacted
3 with such liquid drops (though such contact is not essen-
4 tially required), the fiber stream 7 is blown against a
fiber impinging portion P of a collector 8. The collector
6 8 comprises a net or porous plate of a synthetic resin hav-
7 ing a mesh size of 5 to 200 mesh, preferably 5 to 100 mesh
8 and more preferably 10 to ~O;mesh, and wound about a hollow
9 cylindrical drum 81. The drum 81 has a cylindrical side
wall pierced with a multiplicity of apertures 83. Each of
11 the apertures 83 perferably has an inwardly tapered longi-
12 tudinal section, and is defined by an inner portion 84 and
13 an outer portion 85 having a greater diameter than the inner
14 portion 84 as shown in FIGURES 9 and 10. The apertures 83
are circular in cross section. The fibers blown against the
16 surface of the collector 8 are separated from the fiber
17 stream 7, and form a nonwoven fabric 1. The nonwoven fabric
18 thus formed is compressed by a presser 9 into a predeterm-
19 ined thickness, and wound about a winder 13 after passing
around rolls 71 and 71'. The presser 9 comprises a net or
21 porous plate of the same nature as that of which the col-
22 lector 8 is made, which net or plate extends about drums 91
23 and 91' of the same nature with the drum 81. A fiber col
24 lecting zone 12 is defined between the collector 8 and the
presser 9. A spray 14 is provided for supplying a cooling
26 fluid to the collector 8, if required.
27 The nonwoven fabric of this invention can be manu-
28 factured efficiently by the method as hereinabove described.
29 FIGURE 11 schematically illustrates the process by which the
fibers form a fabric. When the fiber stream 7 formed by a
31 plurality of long fibers is blown into the fiber collecting
32 zone 12 defined between the collector 8 and the presser ~,
33 the individual fibers are intertwined and stacked together
34 to form a nonwoven fabric 1~
The longitudinal sectional plane of the nonwoven
36 fabric 1 as shown at A in FIGURE 1 may have various patterns
37 as shown in FIGURES 3 to 7, which depend on the angle at
--6--
1 which the fiber stream 7 is blown, and/or the relative posi-
2 tion of the collector 8 and the presser 3. More specifi-
3 cally, if the fiber stream 7 is blown at a small angle, or
4 if the collector 8 and the presser 9 are spaced a greater
distance apart from each other, the thin layers 4, 4', 4"
6 have a tendency to lie genera:L.ly straightly as shown in
7 Figure 4. If, on the contrary, the fiber stream 7 is blown
8 at a large angle, or the collector 8 and the presser 9 are
9 brought closer to each other, the thin layers 4, 4', 4" each
have an acutely bent shape as shown in FIGURE 6.
11 The nonwoven fabric of this invention constructed
12 as hereinabove described has a fine hand, and is bulky, and
13 demonstrates excellent results not obtained from any known
14 nonwoven fabric when used for making filter materials, car-
pets, substrates for synthetic leathers, or the like.
