JPH01111055A - Production of nonwoven fabric - Google Patents

Abstract

PURPOSE: To obtain nonwoven cloth having excellent opening property, uniformity and practically sufficient tensile strength by catching fiber streams of ultrafine fibers obtained by melt blowing on a specific catching face. CONSTITUTION: Spun yarns from many spinnerets 22 are dragged and thinned by a high-speed air stream ejected from an air ejecting slit 21 near the spinnerets 22 to form a fibers stream of the ultrafine fibers and the fibers stream is caught by a catching part located below the spinnerets 22. The catching part has a projecting curved face part 8 on the surface and both sides of inclined parts 9 and 10 and is composed of a porous supporter having an aspirating structure on the rear face and a net 6 transferring the surface.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention jets out a molten thermoplastic resin spun from a plurality of spinning holes from a gas jetting slit arranged adjacent to the spinning holes. The present invention relates to a method for producing a nonwoven fabric made of ultrafine fibers by pulling and thinning with high-speed airflow to form a fiber stream of ultrafine fibers, and then collecting and accumulating the fiber stream.

(Prior art) As a method for manufacturing nonwoven fabrics, conventionally, a thermoplastic resin is melt-spun, pulled and thinned by high-speed airflow to form a fiber stream, and then this fiber stream is collected and accumulated to produce a nonwoven fabric. There are techniques disclosed in Japanese Patent Publication No. 49-48921, Japanese Patent Publication No. 8O-5E1825, etc.

The former technique is as shown in FIG. The yarn is continuously spun from
After passing through the spinning hole 26, the spun yarn is pulled and thinned by a high-speed air current ejected from the gas ejection slit 25 arranged adjacent to the spinning hole 26, thereby forming ultra-fine fibers. A fiber stream 27 is formed, collected on a take-up net 30 that moves on a flat collection plate 29, and wound up.

Furthermore, as shown in FIG. 4, the latter technique allows a fiber flow 36 of ultrafine fibers to be moved in the direction of movement of the collection plate 37 from a contact area where the collection plate 37 and the holding plate 38 are in contact with each other via the fibers. The fiber flow 36 is sprayed and accumulated between a collection plate 37 and a holding plate 38, which are provided so that the gap between the collecting plate and the holding plate in the opposite direction increases as the distance from the contact portion increases. At least one of the collection plate 37 and the presser holder 38 has a porous structure, and if necessary, the fiber flow 36 is suctioned from the back side with a blower 18 or 41. This is an attempt to increase the agglomeration effect.

In addition, 17 is a motor, 32 is a guide, 33 is a high-speed air flow source, 34 is a gas jet slit, 35 is a spinning hole, and 40 is an entrained flow.

(Problems to be Solved by the Invention) However, the prior art has the following problems. Third
In the method shown in the figure, the accumulated fibers are scattered under the influence of the entrained flow 28 generated when the high-speed airflow pulling the thermoplastic resin entrains the atmosphere, so in order to form a nonwoven fabric, it is necessary to 29, it is necessary to keep a sufficient distance. Therefore, the nonwoven fabric formed by this method takes a long time to collect the fiber flow, resulting in an uneven nonwoven fabric containing a string-like structure formed by intertwining many fibers, resulting in textile products. The texture, permeability and filtration performance as a filter cannot be expected at all.

In addition, in the method shown in FIG. 4, the spinning hole 35 and the collection plate 37 are
There is no particular limit to the distance between -, and since the fibers 36 can be collected at a position close to the spinning hole 35, the above-mentioned string-like structure will not be formed.
Due to the manufacturing method of stacking, the resulting nonwoven fabric has a cross-sectional structure 42 that is perpendicular to or close to the flow direction of the production line, as shown in the cross-sectional view of FIG. 5, and the tensile strength in this direction is extremely low. It becomes. As a countermeasure to the above, methods have been taken to improve the tensile strength by entangling the nonwoven fabric with needle punches or high-speed airflow ejected from a large number of gas injection holes arranged facing the nonwoven fabric in the post-processing process. Such post-processing damages the nonwoven fabric and reduces the feel of the wAm product, the permeability and filtration performance as a filter, and is therefore not at all preferable as a manufacturing method.

The inventors of the present invention have conducted intensive studies on the process of collecting the fiber flow and making it into a nonwoven fabric. As a result, they found that it is necessary to have good fiber opening properties and to spray the fiber flow uniformly. A curved surface suppresses the influence of entrained airflow accompanying the fiber flow more than a flat surface, and #! The present invention was developed based on the discovery that this method is effective in fixing Ast on a collection plate.

The present invention aims to provide a manufacturing method capable of manufacturing a nonwoven fabric that has excellent permeation performance, excellent filtration performance, and high tensile strength, which were not achieved by conventional methods.

(Means for solving the problems) The present invention takes the following means to solve the problems. That is, the present invention pulls and thins the molten thermoplastic resin spun from a plurality of spinning holes by a high-speed airflow jetted from a gas jetting slit adjacent to the spinning holes, thereby producing ultrafine fibers. forming a fiber flow,
Next, in a method of collecting and accumulating the fiber flow to produce a nonwoven fabric made of ultrafine fibers, the surface is composed of a convex curved surface portion and sloped surface portions extending downward on both sides of the convex curved surface portion, and the back surface thereof has a suction structure. A porous collection surface is provided below the fiber flow, and the surface of the collection surface is provided so that a take-up net moves, and while the take-up net is moved forward, the take-up net is A patented fabric manufacturing method characterized in that the fiber stream is directed and sprayed onto the convex curved surface portion of the collection surface through a holder, and the fiber stream is collected and accumulated in a moving take-up net. .

The present invention will be explained below based on the drawings.

Although FIGS. 1 and 2 show a specific example of the method for producing a nonwoven fabric according to the present invention, the present invention is not necessarily limited to this specific example.

Thermoplastic resins such as polyolefin, polyester, polyamide, polyurethane, polyacrylic, polyfluoroethylene, and polyvinyl chloride resins are supplied to a hopper 16, passed through an extruder 11 and a gear pump 2, and are then quantitatively supplied to a die 3. The fibers are continuously spun from a plurality of spinning holes 22 built into the die 3. A gas ejection slit 21 connected to a high-speed gas source 21 is arranged adjacent to the spinning hole 22, and the spun yarn from the spinning hole 22 is pulled and thinned by the high-speed airflow ejected from the gas ejection slit 21, resulting in ultrafine fibers. A fiber stream is formed. Next, this fiber flow passes through a convex curved surface section 8 and an inclined surface section 9 smoothly connected thereto.
10, and is collected on a take-up net 6 that moves in close contact with a porous collection surface 11 that is sucked by a blower 18 from the back side, and becomes a nonwoven fabric of ultrafine fibers. This nonwoven fabric moves together with the take-up net 6, is separated from the take-up net 6 at a position away from the collection surface 11, and then moves onto the take-up roll 12.
It is rolled up into a product.

The shape of the convex curved surface portion 8 of the collection surface 11 has a radius of 100 to 2, for example.
A part of the cylindrical side surface of 00■■ is considered preferable, but is not particularly limited to this.

In addition, the length of the inclined surface portions 9 and 10 is 500.20, respectively.
Preferably 0 or more fins.

The collection surface 11 has a porous structure, and suction is performed from the back surface with a suction force as required by a blower 18 to enhance the accumulation effect of the met flow. In this sense, this suction method is preferable. In the case of suction using the blower described above, a plurality of blowers or dampers 19, 19' are used.

By using #19, it is possible to distribute the suction force between or within each part of the collection surface 11, and the suction pressure at each position can be set to the minimum suction pressure necessary for forming the nonwoven fabric. is possible.

A preferable example of the porous structure of the collection surface 11 is 5 to 3
Examples include a mesh structure made of metal or plastic with 0 mesh, or a punching plate made of the above materials with a diameter of 3 to 5 fins and a porosity of 30% or more. A preferable example of the take-up net 6 is a net-like structure made of metal or plastic and having 20 to 100 meshes. Particularly preferred is one whose surface is coated with a slippery component such as Teflon.

As shown in FIG. 2, a holding net 13 is installed as necessary on the inclined surface portion 9.10 of the collection surface, and the convex curved surface portion 8 of the collection surface is
This makes it possible to sandwich the nonwoven fabric formed above between it and the take-up net 6.

As the holding net 13, a metal of 5 to 50 meshes,
A net-like structure made of ceramic or plastic impregnated or coated with a mold release agent such as Teflon is preferred because it has good mold release properties and does not damage the nonwoven fabric.

In ftE1 and Figure 2, the fiber flow 4 is the collection surface! The spray is applied to the convex curved surface portion 8 of l, preferably approximately perpendicularly to the top portion, but the approximately upper portion of m is sprayed not only on the top but also on the slightly inclined surface portion 9.
．． This includes a case where the fiber flow 4 is blown approximately vertically with a deviation toward 10. For example, when the convex curved surface section is a cylindrical surface, it is preferable that the radius of the convex curved surface section is deviated from the top of the convex curved surface section horizontally backward or forward within a range of 2Ti-12.

(for production) The above technical means works as follows.

The entrained airflow 14 that accompanies the fiber flow 4 collides with the convex curved surface portion 8 of the collection surface 11 and is distributed to the front and rear thereof, and the fiber flow 4 is formed by being blown onto the curved surface portion 8 of the collection surface 11. The nonwoven fabric is pulled back and forth. The resultant force of this tensile force fixes the nonwoven fabric on the convex curved surface portion 8 of the collecting surface 11, so that it is possible to collect the nonwoven fabric at a position close to the spinning hole 22. There are no soft tissues formed by entanglement, and a uniform nonwoven fabric can be obtained. Furthermore, the suction force required for the convex curved surface portion 8 of the collection surface 11 is extremely small compared to the conventional technology, which is highly effective in reducing the power consumption of the blower.

By the above collection method, the fiber stream 4 is arranged so as to have a laminated structure on the convex curved part of the collection surface 11, which is nearly horizontal to the flow direction of the production line, so that the obtained nonwoven fabric has a practically sufficient tensile strength. It has strength.

The inclined surface portion 9.10 connected to the convex curved surface portion 8 of the collection surface 11 functions as follows. The fiber flow is caused by the convex curved surface portion 8 of the collection surface 11.
At the top, it becomes a nonwoven fabric, but at a position away from the convex curved surface section 8, the entrained airflow 15 is distributed to the front and rear of the convex curved surface section 8.
Due to this, all or part of the nonwoven fabric is peeled off from the take-up net. As a result, the nonwoven fabric is not only disturbed and its quality deteriorates (and in some cases, it becomes impossible to roll it up into a product. In the present invention, inclined surface portions 9 are provided before and after the convex curved surface portion 8 of the collection surface 11. Place 10 and you can do it.

Between each part 8 and 9.10 of the collection surface 11 or each part 8.9.1
Since the suction pressure can be distributed within 0, it is possible to set the suction pressure at each position to the minimum suction pressure necessary for forming the nonwoven fabric. Therefore, the power consumption of the blower used can be reduced, which has a significant effect on reducing manufacturing costs.

The above method is sufficient when producing a nonwoven fabric with a relatively small basis weight fft, but when producing a nonwoven fabric with a large basis weight, the suction force on the inclined surface portion 9.10 of the collection surface 11 is Because of the resistance, it is not transmitted to the surface of the nonwoven fabric, making it difficult to prevent its peeling. In such a case, as shown in FIG. By sandwiching it, you can prevent it from separating.

(Example) Example 1 Using polypropylene with a melt index of 14, the first
A nonwoven fabric was manufactured using the collection equipment shown in the figure.

The convex curved surface part 8 of the collection surface 11 is a 1/4 part cylinder with a radius of 100 mm, and the inclined surface parts 9 and 10 each have a length of 800 mm - 1.40 mm.
A 0 mm flat plate was used. A stainless steel L/SW punching plate with a diameter of 5 fins and an aperture ratio of 50% was used as the porous structure of the collection surface 11, and a 50 mesh stainless steel net was used as the take-up net.

In addition, the collection position of the vAII flow was set at 300 fi below the spinning hole.

Each part 8, 9, 10 of the collection surface 11 is subjected to a static pressure of 2o, t, respectively.
oo, tool ■ The fiber stream of polypropylene was collected by suction with water injection.

Table 1 shows the physical properties of the nonwoven fabric obtained by the above method. In addition, conventional method 1 in Table 1 is a method according to Fig. 3,
The spinning conditions were the same as in the method of the present invention.

In conventional method 1, the diameter is 5■■, the aperture ratio is 50%f)
7. A punching plate made of punchless was used as a collection plate, and the distance from the spinning hole was 1000 mm. −. Further, the same taking-up net as in the method of the present invention was used.

It has been found that the nonwoven fabric obtained by the method of the present invention has superior properties in terms of tensile strength, permeability, and filtration performance compared to nonwoven fabrics obtained by the conventional method.

Example 2 A nonwoven fabric was produced using polyethylene terephthalate having an intrinsic viscosity of IV O, 61 (measured at 30° C. in a mixed solution of phenol/tetrachloroethane = 674) using the collection equipment shown in FIG.

The material, shape, and operating conditions of the collection surface 11 and the take-up net 6 were the same as in Example 1. In addition, in this embodiment, a holding net 13 is arranged on the inclined surface portion 10 of the collection surface 11,
The entrained airflow prevented the nonwoven fabric from IIIIIII.

As the holding net 13, a 30-mesh stainless steel wire mesh coated with Teflon was used.

Table 2 shows the physical properties of the nonwoven fabric obtained by the above method. The manufacturing conditions for Conventional Method 1 in Table 2 were the same as those in Table 1.

It has been found that the nonwoven fabric obtained by the method of the present invention has superior properties in terms of tensile strength, permeability, and filtration performance compared to nonwoven fabrics obtained by the conventional method.

Note that the physical properties in Tables 1 and 2 were measured by the following methods.

Single yarn denier: Microscope equipped with digital micrometer
Measurements were made at n=100 at a magnification of 400 times under 8U, and the average value was calculated.

Fabric weight type fA (g/male): A sheet was cut into a size of 201×201, weighed, and multiplied by 25 to obtain the weight.

Permeation performance: Effective filtration area 19.8 cJ (diameter 5 cs
), and set the sample on a column with a wind speed of 10 cm/se.
Static pressure (-■
The difference was ＾q).

Filtration performance: The number concentration of floating dust in the airflow before and after the sample was measured using a light scattering type dust counter (KC-QIA manufactured by Liono ■) using the same device as in the case of transmission performance, and was determined from the ratio of the two. .

Tensile strength: Based on JIS L-109 (E-1979 general textile testing method) Medium 2.5 cs 1 grip interval 10 c
I did it with m.

Table 1 Polypropylene Melt Index 14 2nd
Table Polyethylene terephthalate IV 0.61 (
Effects of the Invention) The present invention has the following unique effects.

(1) The entrained airflow that accompanies the fiber flow is distributed back and forth by the collection surface, and the nonwoven fabric is fixed on the convex curved surface of the collection surface, allowing collection at a position close to the spinning hole.
There is no intertwined tissue formed by entanglement of many fibers, and a nonwoven fabric with a uniform intertwined surface can be obtained.

■ The fiber flow is arranged on the convex curved part of the collection surface so as to have a laminated structure that is nearly parallel to the flow direction of the production line, and a nonwoven fabric with sufficient tensile strength for practical use can be obtained without any post-processing. .

(3) The suction force required to collect the fiber flow is extremely small compared to conventional methods. Shows great effect in reducing power costs required for suction blowers.

[Brief explanation of the drawing]

1 and 2 are related to the present invention; FIG. FIG. 5 is a side view of the apparatus used in the method, and FIG. 5 is a side view of the nonwoven fabric obtained by the conventional method of FIG. 2...Gear pump 3...Gui 21...Gas jet slit 22...Spinning hole 4...Fiber flow 6...Take-up net 8...Convex curved surface part 9.10...Slanted surface part 11...Collection surface 27... Fiber stream 30... Pick up net 36... Fiber stream 37... Collection plate patent applicant Toyobo Co., Ltd. 22... Tie hole 6... Bow 1 Evil Soint Atsushi 2 I2I 22... #i Finger length 8 L! l! 1 unit [with] Department 6 Hibi + 1 Neft 13... Misaki 4L Net 3c No. 512 May 26, 1988

Claims (1)

[Claims] The molten thermoplastic resin spun from a plurality of spinning holes is pulled and thinned by a high-speed air stream jetted from a gas jetting slit adjacent to the spinning holes to form a fiber stream of ultrafine fibers, and then In a method for collecting and accumulating the fiber stream to produce a nonwoven fabric made of ultrafine fibers, the surface is composed of a convex curved surface portion and sloped surface portions extending downward on both sides of the convex curved surface portion, and the back surface thereof has a suction structure. A porous collection surface is provided below the fiber flow, and the surface of the collection surface is provided so that a take-up net moves, and the take-up net is moved while the take-up net is moved forward. directing the fiber stream to the convex curved surface portion of the collection surface through the
A method for producing a nonwoven fabric, characterized in that the fiber stream is collected and accumulated in a moving take-up net.