JP3758063B2 - Spinneret for melt blow and method for producing nonwoven fabric - Google Patents

Description

【００１７】
実施例１〜５は平均繊維径２〜３μｍでショットの存在しないメルトブロー不織布をフライ状物の発生なしに製造できた。
一方、比較例１〜４は、ショットあるいはフライ状物が発生し、シート品位が著しく劣るものであった。また、比較例５は平均繊維径を細くすることができずフィルター用途等に不適であった。
【００１８】
【発明の効果】
本発明によると、ショットが存在せず均一性に優れた高品位な極細繊維不織布を安定的に製造することを可能とした。
【図面の簡単な説明】
【図１】 本発明における紡糸口金の断面を示す概略図。
【符号の説明】
１：ダイノーズ、２：リップ、３：ノズル、４：オリフィス開口部先端、５：リップ先端面、６：オリフィス、Ｌ：ストット幅、Ｓ：セットバック、θ：頂角[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a melt-blown spinneret and a method for producing a melt-blown nonwoven fabric, and in particular, a spinneret for stably producing a high-quality ultrafine fiber nonwoven fabric excellent in uniformity and free of shots, and a nonwoven fabric using the same. It relates to a manufacturing method.
[0002]
[Prior art]
Conventionally, as a method for producing an ultrafine fiber nonwoven fabric by a melt blow method in which a thermoplastic resin is melted and discharged, pulled and thinned into a sheet by a high-temperature and high-speed fluid, JP-A-49-10258 and JP-A-50-121570 are disclosed. Etc. are known. Moreover, as a method for producing a melt blown nonwoven fabric in which the generation of shots is suppressed, Japanese Patent Application Laid-Open Nos. 48-48922 and 2-289162 are known.
However, in Japanese Patent Laid-Open No. 48-48922, although the occurrence of shots can be suppressed, it is not sufficient, and the filtration performance is insufficient for filter applications and the like, and there is also a problem in the quality.
Japanese Patent Application Laid-Open No. 2-289162 discloses a method of creating an asymmetric state on the left and right sides of the orifice and suppressing the occurrence of shots, but the effect is exhibited only within a limited range of control of the asymmetric state. Therefore, when manufacturing a variety of products having different qualities, it is necessary to set the asymmetric state extremely precisely for each switching, which is not practical.
[0003]
[Problems to be solved by the invention]
The present invention provides a spinneret capable of stably producing a high-quality melt-blown nonwoven fabric having no shot, which is insufficiently solved by conventional methods, and excellent in uniformity, and a method for producing a nonwoven fabric using the same. To submit.
[0004]
[Means for Solving the Problems]
That is, according to the present invention, in a spinneret in which a plurality of nozzles (3) each including a dynoses (1) and a pair of lips (2) are arranged in a row, the cross-sectional shape of the dynoses (1) is arranged via an orifice (6). It is an isosceles triangle, and the slit width (L), which is the distance between the long side of the dynoses (1) and the lip (2), which is the traction fluid flow path, is 0.3 to 2.0 mm, and the dynoses (1) The setback (S), which is the distance from the orifice opening tip (4) to the lip tip surface (5), is 0 to 2.0 mm, and the ratio of the slit width (L) to the setback (S) (S / L) is 0.7 to 1.3, and the melt blown spinneret and the spinneret described above are used to melt and discharge the thermoplastic resin from the orifice, By ejecting fluid , It led thinning the thermoplastic resin, and then a method for producing a melt-blown nonwoven fabric, characterized in that the sheeting.
[0005]
The present invention is described in detail below.
It is important that the dynoses (3) in the present invention have an isosceles triangle through an orifice (6) whose cross section passes through the center. If the left and right sides are different unequal triangles, the right and left traction fluid ejection angles differ, and as a result, when the thermoplastic resin discharged from the orifice is pulled down, it collides with the lip tip, This results in a problem that the shot is mixed into the sheet and the sheet quality is remarkably lowered. In addition, the molten resin adhering to the tip of the lip stays for a long period of time, causing thermal deterioration and blocking the nozzle holes, resulting in a reduction in productivity.
[0006]
It is preferable that the orifice diameter of the dynoses (1) is 0.1 to 1.0 mm.
Further, the pitch interval of the orifices is preferably 0.5 to 2.0 mm, and the spinneret has a structure in which a plurality of nozzles (S) are arranged in a row at the interval. Furthermore, it is preferable that the apex angle of dynoses (1) is 45 ° to 100 °. In addition, the high-temperature and high-speed fluid used in the present invention is mainly a gas such as air, steam, or inert gas, and in particular, heated air is generally used.
[0007]
As shown in FIG. 1, the traction fluid flow path slit width (L) of the nozzle (3) is the above-described long side of the dynoses (1) having an isosceles cross section and a pair of left and right lips (2 ) In the cross-sectional direction of the slit-shaped flow path. The setback (S) refers to the vertical distance from the orifice opening tip (4) to the lip tip surface (5) of the die nose (1) shown in FIG.
[0008]
In the present invention, it is important that the ratio (S / L) of the slit width (L) to the setback (S) is 0.7 to 1.3, preferably 0.8 to 1. 2 or less. If the ratio (S / L) is less than 0.7, the setback (S) becomes too small with respect to the slit width (L). Therefore, the thinning becomes unstable due to the disturbance of the external air flow and a shot is generated, or the thinning is insufficient and it is difficult to reduce the fiber diameter. On the other hand, when the value of the ratio (S / L) exceeds 1.3, the fine fiber breaks inside the nozzle, and the generation of shots and the molten thermoplastic resin during thinning adhere to the lip tip. Since it becomes drip-like and sheet quality is remarkably impaired, it is not preferable.
[0009]
The slit width (L) is important to be 0.3 mm or more and 2.0 mm or less, preferably 0.4 mm or more and 1.6 mm or less. If the slit width (L) is less than 0.3 mm, the production and assembly of the spinneret need to be very precise, which is not practical. On the other hand, if it exceeds 2.0 mm, a large amount of traction fluid is required to reduce the traction, making it impractical in terms of cost.
[0010]
Furthermore, it is important that the setback (S) is 0 mm or more and 2.0 mm or less, and preferably 0.3 mm or more and 1.6 mm or less. When the setback (S) is less than 0 mm, that is, when the tip of the orifice opening protrudes from the lip tip surface (5), the thinning becomes unstable due to the turbulence of the entrained flow accompanying the ejected traction fluid. And a shot occurs. In addition, since the tip of the orifice opening protrudes to the outside, there is a risk of problems in terms of maintenance such as damage to the tip during handling. On the other hand, if it exceeds 2.0 mm, the thinned fiber breaks inside the nozzle, which is not preferable because it involves the generation of shots and flies.
[0011]
In the present invention, the slit width (L) and the setback (S) are set to large values as the single-hole discharge amount of the thermoplastic resin increases and the melt viscosity of the thermoplastic resin increases. It is preferable to do.
In the present invention, the above requirements are satisfied, that is, the slit width (L) of the traction fluid flow path and the setback (S) are approximately equal to each other, so that the melted and discharged thermoplastic resin is sufficiently thinned. It is possible to proceed stably and stably.
[0012]
The thermoplastic resin used in the present invention is an olefin resin such as polyethylene or polypropylene, a polyester resin such as polyethylene terephthalate or polybutylene terephthalate, a polyamide resin such as nylon 6, nylon 66 or nylon 46, or polyvinyl chloride. Polyvinylidene chloride, polystyrene, polycarbonate and the like are not particularly limited, and any thermoplastic resin can be applied.
[0013]
The melt-blown nonwoven fabric produced by the method of the present invention is excellent in uniformity with no occurrence of shots, and is very high-grade, so it is used for filters such as air filters and liquid filters, battery separators, masks, medical and sanitary materials, It can be applied to various uses such as heat insulation materials and agricultural materials.
[0014]
【Example】
Hereinafter, the present invention will be specifically described by way of examples. The characteristic values described in the examples were determined by the following measurement methods.
a. A scanning electron micrograph of the average fiber diameter meltblown nonwoven fabric was taken at a magnification of 1000 to 2000 times, the width of 200 fiber side surfaces arbitrarily extracted from the photograph was measured, and determined by arithmetic average.
b. The state of occurrence of shots was investigated by transmitting the shot melt blown nonwoven fabric with a visible light source and observing the surface by visual inspection.
[0015]
(Examples 1-5, Comparative Examples 1-5)
In the melt blow nozzle having the structure schematically shown in FIG. 1, a nozzle having a hole diameter of 0.3 mm, a hole pitch of 1.0 mm, and a die nose apex angle of 60 ° is used, and the slit width (L) and setback (S) are changed. Then, various thermoplastic resins were changed in the single-hole discharge amount, the traction fluid conditions were adjusted so that the average fiber diameter was 2 to 3 μm, and a melt blown nonwoven fabric was produced.
[0016]
[Table 1]

[0017]
In Examples 1 to 5, melt blown nonwoven fabrics having an average fiber diameter of 2 to 3 μm and no shots could be produced without generation of fried products.
On the other hand, in Comparative Examples 1 to 4, shots or flies were generated, and the sheet quality was extremely inferior. In Comparative Example 5, the average fiber diameter could not be reduced, which was unsuitable for filter applications.
[0018]
【The invention's effect】
According to the present invention, it is possible to stably produce a high-quality ultrafine fiber nonwoven fabric having no shot and excellent in uniformity.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a cross section of a spinneret in the present invention.
[Explanation of symbols]
1: Dynoze, 2: Lip, 3: Nozzle, 4: Tip of orifice opening, 5: Lip tip, 6: Orifice, L: Stot width, S: Setback, θ: Vertical angle

Claims (2)

In a spinneret in which a plurality of nozzles (3) comprising a dynoses (1) and a pair of lips (2) are arranged in a row, the cross-sectional shape of the dynoses (1) is an isosceles triangle through an orifice (6). The slit width (L), which is the distance between the long side of the dynoses (1) and the lip (2) serving as the traction fluid flow path, is 0.4 to 2.0 mm, and the orifice opening tip of the dynoses (1) ( 4) The setback (S), which is the distance from the lip tip surface (5), is 0.3 to 2.0 mm, and the ratio of the slit width (L) to the setback (S) (S / L) A spinneret for melt-blowing, characterized in that is 0.7 to 1.2 .   Using the spinneret according to claim 1, the thermoplastic resin is melted and discharged from an orifice, and a high-temperature and high-speed fluid is ejected from a traction fluid flow path, whereby the thermoplastic resin is pulverized and then sheeted. A process for producing a meltblown nonwoven fabric characterized by

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