JP2001040566A - Nozzle piece and melt-blown nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle piece for simultaneously and integrally forming a nonwoven fabric comprising fibers having largely different shapes and dimensions, respectively, in order to obtain a highly precise filter raw material having a long life, and to provide a melt-blown method nonwoven fabric produced using the nozzle piece. SOLUTION: This nozzle piece has nozzle orifices formed in a row in the tip portion of a die. Therein, circular orifice nozzles and deformed orifice nozzles are provided side by side in a row. The ratio L/t of the length L of the side of the deformed orifice nozzle to the thickness (t) of the side is 1.5 to 3.0, and the ratio L/D of the long side of the deformed orifice nozzle to the diameter D of the circular orifice nozzle arranged on the same line is 1.5 to 3.0. Two to four circular orifice nozzles are laid between the adjacent deformed orifice nozzles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle piece for a melt-blown non-woven fabric, in which circular hole nozzles and irregular-shaped nozzles are regularly arranged, and a melt-blown non-woven fabric produced by using the nozzle pieces and having different cross-sectional shapes. About.

[0002]

2. Description of the Related Art A method for producing a nonwoven fabric by a melt blow method has been known for a long time.
S. Naval Research Laborato
ry (Report No. 5265, February
y, 11, 1959). Further, Japanese Patent Application Laid-Open No. 50-46972, which is a patent of Exxon Chemical Co., Ltd., which first industrialized this production method, or Mel Blowing-aone-step
web process for new now
even products (Vol. 56, No. 4)
April 1973, Tappi Journa
1). According to this technique, a plurality of nozzles having a fixed circular cross-section and a fixed hole diameter as shown in FIG. Then, the discharged molten polymer is spun in a high-temperature jet stream to form a nonwoven fabric made of ultrafine fibers having a relatively uniform diameter. The fiber diameter of the nonwoven fabric obtained here can be arbitrarily changed within a certain limit by adjusting the production conditions of the melt blowing method, for example, the die temperature, the discharge amount, the amount of air, and the like as the dominant factors. Is characterized by being relatively uniform and having a narrow fiber diameter distribution.

When such a nonwoven fabric is applied to an air filter or a liquid filtration filter, its collection efficiency, accuracy and life depend on the thickness of the nonwoven fabric and the size of the fiber diameter under the same basis weight. For example, in order to increase the precision of filtration, it is customary to reduce the fiber diameter, and further to perform compaction using a hot calender roll to reduce the pore size of the nonwoven fabric. However, when such a nonwoven fabric is used for a filtration filter, simply reducing the fiber diameter causes
Although the accuracy of the filtration is improved, there is a disadvantage that the collected particles are clogged at an early stage and the life of the filter is shortened.

[0004] In order to improve this, a filter in which nonwoven fabrics having different constituent fiber diameters are laminated is generally used, and the layers are bonded with an adhesive or pressed with a hot calender roll. I have. However, in such a method, it is necessary to separately manufacture nonwoven fabrics having different fiber diameters, and therefore, a bonding and joining process is required. In addition, the filter manufacturing process becomes complicated, and at the same time, delamination may occur at the time of use. Also, there is a problem in terms of the quality of the filter, such as separation and elution of the adhesive during use as a filter. There were many. JP-A-2-33368 discloses a technique in which a nonwoven fabric made of ultrafine fibers having an irregular cross section can be manufactured from a special melt-blow nozzle.
Japanese Patent No. 31353 discloses a technique using a nozzle piece in which circular nozzles having different hole diameters are arranged.
No mention was made of the effect of combining the circular and irregular nozzles, and the filter was not yet satisfactory as a filter having a low pressure drop and a high collection rate, and a liquid filtration filter material having a high precision and a long life. .

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to obtain a high-precision, long-lasting filter material by integrally forming a nonwoven fabric having greatly different sectional shapes and dimensions from constituent fibers. It is an object of the present invention to provide a nozzle piece for forming a nonwoven fabric and a melt-blown nonwoven fabric produced by the nozzle piece.

[0006]

Means for Solving the Problems The present inventor has conducted intensive studies in order to solve the above-mentioned problems, and as a result, in the same nozzle piece, a circular hole and a nozzle having a modified hole are arranged on the same line, and the combination thereof is optimized. By using a melt-blown non-woven non-woven nozzle piece, a fiber having a circular cross section can be entangled with a fiber having an irregular cross section at the same time as melt spinning, and by changing the size and composition ratio of the cross section of both fibers, an ultra-fine fiber can be obtained. It has been found that non-woven fabrics having high compression resistance and high bulk resistance can be manufactured, and without impairing the filter life, non-woven fabrics with high filtration accuracy can be manufactured simultaneously and integrally, thus completing the present invention. .

That is, the present invention relates to a nozzle piece having a nozzle hole formed in a row at the tip end of a die, wherein a circular hole nozzle and a modified hole nozzle are provided on the same line. The ratio L / t of the length L of the side and the thickness t of the side is 1.5 to 3.0, and the ratio of the long side L and the diameter D of the circular hole nozzle arranged on the same line. L / D is 1.5 to 3.0, and a circular hole nozzle is laid between adjacent deformed hole nozzles at 2 to 4 places. It is a melt blown nonwoven fabric manufactured using a nozzle piece.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Nozzle Piece For the nonwoven fabric by the melt blow method, usually, a die having a sectional structure as shown in FIG. 10 is used, and the nozzle piece 1 is attached to the tip of the die. At the forefront of this nozzle piece, in the prior art, as shown in FIG. 2, a large number of circular hole nozzles perforated in a row are arranged, and molten polymer is discharged from this nozzle, and in a high temperature air flow from an air slit. It is spun to form a nonwoven fabric made of ultrafine fibers. The constituent fibers of the nonwoven fabric produced by this method are characterized by having the same cross-sectional shape, a relatively uniform fiber diameter, and a narrow fiber diameter distribution.

In the nozzle piece for a melt-blown nonwoven fabric according to the present invention, the nozzles are not only circular holes, but irregularly shaped nozzles are arranged between a large number of circular nozzle holes perforated at regular intervals as shown in FIG. Things. The reason for using a deformed hole nozzle is that a deformed fiber having a large outer length can be obtained with a small cross-sectional area, and this and a fine circular cross-section fiber are entangled during melt blowing, and as a result, the fiber structure of the nonwoven fabric becomes three-dimensional. This is because it is suitable for imparting bulkiness.

The shape of the irregularly shaped nozzle includes a cross shape (plus type), a Y shape, a convex shape, an H shape, and a star shape as shown in FIG. (Plus type), Y type, and convex type are preferable. The shape of the irregular hole nozzle is
4, the ratio L / t of the length L of the side to the thickness t of the side is 1.5 to 3.0, more preferably 2.0 to 2.5. . Taking the cross-shaped nozzle as an example, if the slenderness ratio L / t of the long side L and the thickness t of the side is less than 1.5, the three-dimensional effect of the entangled fibers in the nonwoven fabric is weakened, while exceeding 3.0. This makes it difficult to form an irregular fiber shape in melt spinning.

In the size relationship between the modified hole nozzle and the circular hole nozzle, the dimensional ratio L / D of the long side L of the modified hole nozzle and the diameter D of the circular hole nozzle arranged on the same line.
Is from 1.5 to 3.0, preferably from 2.0 to 2.5.
If the L / D is less than 2.0, the dimensional difference between the deformed hole and the circular hole is small, and there is no steric effect described above. If the L / D exceeds 3.0, the polymer discharge amount of each of the deformed hole and the circular hole is reduced. There is too much difference, resulting in a nonwoven fabric with shots and fries, which is not preferable in appearance and filter performance.

In the arrangement of the circular hole nozzles and the irregular hole nozzles arranged on the same line, it is necessary to insert and install two to four circular hole nozzles between adjacent irregular hole nozzles as shown in FIG. is there. If the number of circular hole nozzles to be inserted is less than two, the number of circular microfine fibers formed by the decrease in the number of circular hole nozzles relatively decreases, and when used as a filter, the filtration accuracy is reduced. On the other hand, if the number of circular hole nozzles exceeds four, the number of fibers with irregular cross-sections relatively decreases, and the desired compression resistance and bulkiness cannot be obtained.

The size of the nozzle described above is 1 μm
In order to smoothly and stably produce a nonwoven fabric having an average fiber diameter of up to 20 μm or a nonwoven fabric having an average fiber diameter of up to 20 μm, the hole diameter D of the circular nozzle is preferably 0.2 mm to 1.2 m.
m, more preferably in the range of 0.3 mm to 1.0 mm. When D is less than 0.2 mm, it becomes difficult to mechanically pierce the nozzle, and the nozzle is easily clogged during operation, which is not practical. On the other hand, when D exceeds 1.2 mm, it is difficult to reduce the fiber.

By defining the shape of the nozzle piece of the present invention as described above, the melt-blown non-woven fabric of the present invention is a non-woven fabric composed of fibers having an average fiber diameter of 1 to 20 μm formed by a circular nozzle. By entanglement of fibers having a three-dimensional bulk in a deformed cross section by a deformed hole nozzle, the internal void of the nonwoven fabric is increased,
Further, the sag of the fiber due to compression during use is reinforced, and as a result, the filter life can be extended. That is,
When performing melt blow using the nozzle piece of the present invention,
Fibers having a circular cross section and an irregular cross section are simultaneously spun, entangled in a high-speed air stream, and collected on a moving screen provided below to form a nonwoven fabric temporarily.

2. Meltblown nonwoven fabric The meltblown nonwoven fabric of the present invention is a single nonwoven fabric produced by using a meltblowing die provided with the above-mentioned nozzle piece and in which fibers having a circular cross section and an irregular cross section are entangled in the same nonwoven fabric. The fiber configuration of the nonwoven fabric is a melt-blown nonwoven fabric having a bulky three-dimensional structure in which a small number of irregular cross-section fibers are used as an aggregate, and a large number of circular cross-section fibers having a smaller diameter are entangled around the aggregate. As the number of irregular cross-section fibers, less than the circular cross-section fibers, the average fiber diameter of the circular cross-section is set in the range of 1 to 20 μm depending on the conditions of melt blowing, in which case, the size of the irregular cross-section fibers, the circular cross-section It has an outer dimension 5 to 20 times larger than the fiber. This is because in the process of drawing and solidifying into fibers, the difference in diameter of the fibers discharged from the nozzles having the respective shapes of the circular hole nozzle and the modified hole nozzle is increased.

The thermoplastic resin suitable for the melt blown nonwoven fabric of the present invention includes polypropylene, high density polyethylene, low density polyethylene, ethylene / propylene copolymer, copolymer of ethylene and α-olefin, polyamide, polyethylene terephthalate, polybutylene Examples include terephthalate, polycarbonate, polyarylene sulfide, and thermoplastic polyurethane. These resins are used alone, but blended and alloyed resins can also be used. If necessary, pigments, dyes, additives for stabilizing heat and weather resistance, inorganic fillers, and the like can be added to these resins.

The melt blown nonwoven fabric of the present invention is useful as a material for filters and the like. That is, while the ultra-fine circular cross-section fibers occupying most of the nonwoven fabric increase the filtration accuracy,
The irregular cross-section fiber entangled with this serves as a kind of reinforcing material, secures a three-dimensional space inside the nonwoven fabric, and increases the particle collection capacity. Thus, a high-performance filter material that can maintain filtration accuracy for a long period of time is obtained. This filter material is
Since a single nonwoven fabric material is used, a plurality of nonwoven fabrics can be bonded or thermocompression-bonded without the need for a step, and there is an advantage that there is no deterioration or delamination during processing.

[0018]

The present invention will be described in detail with reference to the following examples and comparative examples. The evaluation was performed using the following method. (1) Fiber diameter: The diameter of the fiber with a circular cross section and the diameter of the fiber with an irregular cross section were measured with a scanning electron micrograph. (2) Thickness of nonwoven fabric: HT measured by a high load method and LT measured by a low load method were measured, and the ratio LT / H of both was measured.
Calculate T. Usually, LT> HT, and the closer the values are, that is, the smaller the LT / HT value, the smaller the change in thickness with respect to compression and the smaller the sag in thickness, and this is used as an index of compression resistance. . (3) Liquid Filtration Performance: Initial Filtration Efficiency: The capture rate of fine particles captured on the nonwoven fabric in the early stage of use was determined by weight measurement. Filtration life: when the fine particle suspension is filtered, when the pressure is increased by 1 kg / cm ² from the initial pressure, that is, pressure loss △
The filtration life was defined as the flow rate (unit: liter) up to P = 1 kg / cm ² . In addition, the following apparatus and conditions were used for the measurement of the filtration performance. Measuring device: TSU-47B type liquid filter evaluation device manufactured by ADVANTEC Co., Ltd. Fine particles: JIS 11 Liquid passing speed: 500 cc / min constant (4) Air filter performance: Shibata Chemical mask tester AP
Using -6310, the linear velocity of ventilation air containing NaCl particles (3 microns) was kept constant at 26.5 cm / sec, and pressure loss and particle collection efficiency were measured.

Example 1 A polypropylene resin having a melt flow rate of 40 was melt-plasticized by an extruder, introduced into the following die via a polymer line, and heated under the following conditions from the following nozzle piece attached to the tip of the die. The discharged resin was discharged into the atmosphere together with the compressed air, and the discharged resin was formed into a fibrous form. The fibrous form was accumulated on a conveyor, and a nonwoven fabric was formed by entanglement of the fibers and self-adhesion. At this time, the resin discharge amount, air flow rate,
The running speed of the conveyor was adjusted to produce a nonwoven fabric having an average fiber diameter of 5 μm and a basis weight of 40 g / m ² . The performance of the obtained nonwoven fabric was evaluated, and the results are shown in Table 1. (1) Die: In the cross-sectional structure of the die shown in FIG. 10, the air slit width G = 1.5 mm and the nozzle tip angle θ = 60.
And the air lip opening w = 1.5 mm. (2) Nozzle piece: Combination of deformed nozzle (cross-shaped) A and circular nozzle B Side length L of the deformed nozzle = 0.80 mm Side thickness t of the deformed nozzle t = 0.35 mm L / t = 2.28 Circular nozzle hole diameter D = 0.35 mm L / D = 2.28 Pitch interval between hole centers = 1.4 mm Number of circular nozzle holes between irregular nozzles = 3 Irregular / circular nozzle arrangement: FIG. 6 (−ABBBAA)
-) (3) Operating conditions for nonwoven fabric production: extruder temperature 330 ° C Screw rotation speed 60 rpm Resin discharge amount 3-6 kg / hr Die temperature 300 ° C Die-to-conveyor distance 200 mm Air temperature 300 ° C Air flow rate 3-5 Nm ³ / min Die Width 50mm

Example 2 A nonwoven fabric was manufactured and evaluated in the same manner as in Example 1 except that the shape of the nozzle having the irregular shape was changed to Y-shape and the dimensions of the sides were set as follows. Table 1 shows the results. Nozzle piece: Combination of deformed nozzle (Y type) A and circular nozzle B Side length L of deformed nozzle L = 0.80 mm Side thickness t of deformed nozzle t = 0.35 mm L / t = 2.28 Circular nozzle hole diameter D = 0 .35 mm L / D = 2.28 Pitch interval between hole centers = 1.4 mm Number of circular nozzle holes between irregular nozzles = 3 Irregular / circular nozzle arrangement: FIG. 6 (-ABBBBA)
−)

COMPARATIVE EXAMPLE 1 In Example 1, a nozzle piece (width 50) in which the following discharge holes B having a circular nozzle shape were formed in a straight line.
A nonwoven fabric was produced and evaluated in the same manner as in Example 1 except that the non-woven fabric was used. Table 2 shows the results. Nozzle piece: Hole diameter D = 0.35 mm Pitch interval between hole centers = 1.4 mm Circular nozzle arrangement: FIG. 2 (-BBBBBB-)

Comparative Example 2 In Example 1, a nozzle piece (width 500 mm) was used in which the following discharge holes B in which all the nozzles were arranged only in irregular holes A (cross-shaped) were formed in a straight line. In the same manner as in Example 1, a nonwoven fabric was manufactured and evaluated. Table 2 shows the results. Nozzle piece: Side length L of deformed nozzle L = 0.80 mm Side thickness t of deformed nozzle t = 0.35 mm L / t = 2.28 Pitch interval between hole centers = 1.4 mm Deformed nozzle arrangement: FIG. 7 (−AA) -A-A-A-)

Comparative Example 3 A nonwoven fabric was produced in the same manner as in Example 1 except that the following nozzle pieces in which five circular nozzles were arranged between the deformed hole nozzles A-A were used. went. Table 2 shows the results. Nozzle piece: Combination of deformed nozzle (cross-shaped) A and circular nozzle B Side length L of deformed nozzle L = 0.80 mm Side thickness t of deformed nozzle t = 0.35 mm L / t = 2.28 Circular nozzle hole diameter D = 0 .35 mm L / D = 2.28 Pitch interval between hole centers = 1.4 mm Number of circular nozzle holes between irregular nozzles = 5 Irregular / circular nozzle arrangement: FIG. 8 (-ABBBBB-)
BA-)

Comparative Example 4 A nonwoven fabric was manufactured and evaluated in the same manner as in Example 1 except that the side length and the side thickness of the irregularly shaped nozzle were set as follows. Table 2 shows the results. Nozzle piece: Combination of deformed nozzle (cross-shaped) A and circular nozzle B Side length L of deformed nozzle L = 0.50 mm Side thickness t of deformed nozzle t = 0.35 mm L / t = 1.42 Circular nozzle hole diameter D = 0 .35 mm L / D = 1.42 Pitch interval between hole centers = 1.4 mm Number of circular nozzle holes between irregular nozzles = 3 Irregular / circular nozzle arrangement: FIG. 6 (−ABBBAA)
−)

Comparative Example 5 A nonwoven fabric was produced and evaluated in the same manner as in Example 1, except that the side length and the side thickness of the modified hole nozzle were set as follows. Table 2 shows the results. Nozzle piece: Combination of deformed nozzle (cross) A and circular nozzle B Side length L of deformed nozzle L = 1.2 mm Side thickness t of deformed nozzle t = 0.35 mm L / t = 3.42 Circular nozzle hole diameter D = 0 .35 mm L / D = 3.42 Pitch interval between hole centers = 1.4 mm Number of circular nozzle holes between irregular nozzles = 3 Irregular / circular nozzle arrangement: FIG. 6 (−ABBBAA)
−)

Comparative Example 6 In Example 1, except that a nozzle having a circular hole nozzle having the same outer diameter was used instead of the irregularly shaped nozzle,
A nonwoven fabric was manufactured and evaluated in the same manner as in Example 1.
Table 2 shows the results. Nozzle piece: Combination of large circular nozzle hole A and small circular nozzle hole B Large circular nozzle hole diameter DL = 0.80 mm Small circular nozzle hole diameter D = 0.35 mm DL / D = 2.28 Pitch interval between hole centers = 1 .4 mm Number of small circular nozzle holes between large circular nozzles = 3 Large circular / small circular nozzle arrangement: FIG. 10 (−ABBBB)
-A-)

[0027]

[Table 1]

[0028]

[Table 2]

As is clear from Tables 1 and 2, the nonwoven fabric obtained by using the nozzle piece of the present invention has an excellent life without lowering the liquid filtration efficiency, and also has an excellent air filter. Particle collection efficiency and pressure loss can be reduced (Examples 1 and 2). On the other hand, Comparative Example 1, which is a conventional method, has a lower liquid filtration efficiency and a shorter life than Example 1 or 2 of the present invention, and also has a high pressure loss as an air filter. Although the service life of the liquid filtration was increased, the filtration efficiency was greatly reduced, and the pressure loss of the air filter was reduced, but the particle collection efficiency was significantly reduced (Comparative Example 2), and the large and small circular holes were used. When the nozzles are used, although better than Comparative Example 1, the difference in the ejection amount from the large and small nozzles is large, and shots and fly are likely to be mixed (Comparative Example 6). In addition, when the number of circular nozzle holes is increased, the effect of the modified hole nozzle is not seen in the configuration of the fibers of the nonwoven fabric because the number of the modified sectional fibers is too small as compared with the number of the ultrafine circular sectional fibers (Comparative Example). 3). Furthermore, when the shape of the modified nozzle hole is approximated to a circle, the size of the modified cross-section fiber is not so different from the diameter of the circular cross-section fiber,
If the effect of the modified cross-section fiber does not appear (Comparative Example 4), and the cross-sectional area of the modified hole nozzle and the circular hole nozzle are largely different, the discharge amount of the resin from the nozzle becomes uneven, and the stable stable polymer discharge is performed. In the process of producing a nonwoven fabric, spun fibers called fly are generated, and the appearance of the nonwoven fabric remarkably degrades.In addition, polymer bulk particles called shots are mixed with the fiber, and the nonwoven fabric becomes nonwoven fabric. The thickness, the basis weight and the uniformity of the texture are significantly impaired (Comparative Example 5).

[0030]

According to the non-woven fabric obtained by using the nozzle piece for melt-blown non-woven fabric according to the present invention, the ultra-fine circular cross-section fiber occupying most of the non-woven fabric improves the filtration accuracy, while the irregular cross-section fiber entangled with this is a kind of non-woven fabric. It serves as a reinforcing material, secures a three-dimensional space inside the nonwoven fabric, and increases the particle collection capacity. Thus, a high-performance filter material that can maintain filtration accuracy for a long period of time is obtained. Since this filter material is a single nonwoven material, a plurality of nonwoven fabrics need not be bonded or thermocompression-bonded, and there is an advantage that there is no deterioration or delamination during processing.

[Brief description of the drawings]

FIG. 1 is an example of a nozzle hole arrangement of a nozzle piece of the present invention.

FIG. 2 is a nozzle hole arrangement diagram of a conventional nozzle piece.

FIG. 3 is a diagram showing an example of the shape of a modified nozzle hole.

FIG. 4 is a diagram showing a side length and a thickness of a shape of a modified nozzle hole.

FIG. 5 is an example of an arrangement diagram of circular hole nozzles and odd-shaped nozzle holes.

FIG. 6 is an example of an arrangement diagram of circular hole nozzles and odd-shaped nozzle holes.

FIG. 7 is an example of an arrangement diagram of odd-shaped nozzle holes.

FIG. 8 is an example of an arrangement diagram of circular hole nozzles and odd-shaped nozzle holes.

FIG. 9 is an example of an arrangement diagram of large and small circular nozzle holes.

FIG. 10 is a sectional view of a die.

[Explanation of symbols]

 1 Nozzle Piece 2 Air Lip A Deformed Hole Nozzle B Circular Hole Nozzle L Length of Deformed Hole Side t Thickness of Deformed Hole G Air Slit w Air Lip Opening θ Nozzle Tip Angle

Claims (3)

[Claims] 1. A nozzle piece having a nozzle hole formed in a line at a tip end of a die, wherein a circular hole nozzle and a non-circular hole nozzle (hereinafter, referred to as a modified hole nozzle) are provided on the same line. The ratio L / t of the length L of the side of the modified hole nozzle to the thickness t of the side is 1.5 to 3.0, and the long side L of the modified hole nozzle and the circular hole nozzle arranged on the same line. A ratio L / D of the diameter D is 1.5 to 3.0, and a circular hole nozzle is provided between adjacent deformed hole nozzles.
A nozzle piece for a melt-blown nonwoven fabric, which is laid at two to four places. 2. The nozzle piece for a melt-blown nonwoven fabric according to claim 1, wherein the shape of the irregularly shaped nozzle is a cross shape, a Y shape, or a convex shape. 3. A melt-blown nonwoven fabric comprising fibers having different cross-sectional shapes spun simultaneously using the nozzle piece for meltblown nonwoven fabric according to claim 1 or 2.