JPH05321115A - Laminated nonwoven fabric and its production - Google Patents

Abstract

PURPOSE:To obtain a new laminated nonwoven fabric having a multilayered structure by forming according to a melt-blowing method and a method for producing the nonwoven fabric. CONSTITUTION:The objective laminated nonwoven fabric comprises a front melt-blown nonwoven fabric layer and a back melt-blown nonwoven fabric layer having at least one mutually different average diameter, constituent fiber material and density of the constituent fiber in the front and the back of an interlayer containing the constituent fibers of the adjacent front and the back layers mixed therein. Both the nonwoven fabric layers are laminated through the interlayer. The melt-blown fiber is laminated on a moving collection surface while jetting at least two rows of melt blowing jet streams and rocking the jetting streams in the direction at substantially right angles from the jetting direction so as to overlap the two rows of melt-blown jetting streams.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a peculiar non-woven fabric by a melt blow method, and more specifically, at least one of the average diameter of constituent fibers, the constituent fiber material and the density of the constituent fibers forms different surface layers. The present invention relates to a laminated non-woven fabric in which a melt-blown non-woven fabric layer and a melt-blown non-woven fabric layer serving as a backing layer are laminated under a unique structure, and a method for producing the same.

[0002]

Nonwoven materials produced by the meltblowing method are well known and widely used in various forms for agricultural, industrial, medical, sanitary and household products. This melt-blowing method usually involves heating a thermoplastic polymer to form a melt, extruding the melt from a die having multiple orifices, and heating gas consisting of air into the melt extruded from the die orifice. It consists of forming filaments or fibers that have been sprayed and made into fibers, and collecting the melt blow jet stream in which the fibers and gas are mixed on a collecting surface such as a drum or a porous belt.

Such a melt-blowing method is known,
For example, a manufacturing method is proposed in Japanese Examined Patent Publication No. 56-33511. Products that are manufactured by the melt-blowing method and are very familiar are napkins, wipers, filters for air cleaning, sanitary products, incontinence pads, etc. The characteristics are such that the liquid is collected, or the liquid absorption speed and liquid retention due to the capillary phenomenon of the ultrafine fiber layer are good.

On the other hand, in recent years, melt blown nonwoven fabrics made of different fiber diameters and different polymers have been laminated. This is because new excellent functions can be exhibited by laminating and compositing meltblown nonwoven fabrics having different functions.

[0005]

However, in order to laminate the meltblown fiber layers, a single meltblown fiber sheet is laminated by the number of layers to be laminated and adhered by, for example, a hot embossing roller or the like. 62-282
As disclosed in Japanese Patent No. 057, it was necessary to arrange melt-blowing method devices by the number of laminated fiber layers to collect the melt-blowing jet stream on the porous belt.
Here, in the method of stacking meltblown fiber sheets and bonding them with a hot embossing roller, a thin fiber layer, for example, a basis weight of 50
A melt-blown fiber layer of g / m ² or less has a limitation on the basis weight of the fiber layer that can be laminated due to reasons such as tearing and wrinkles that easily occur during the bonding operation process using the hot embossing roller. In the method of arranging as many melt-blowing devices as possible and collecting and stacking the melt-blowing jet on the porous belt, the restriction on the basis weight of the fiber layers that can be laminated can be avoided, but when laminating multiple layers, the entire device As a result, it had to be large in scale, and energy consumption increased as a whole.

An object of the present invention is to solve the above problems of the conventional method, to provide a novel multilayer nonwoven fabric having a multi-layer structure formed by a melt blow method, and to provide a manufacturing technique thereof.

[0007]

The structure of the laminated nonwoven fabric of the present invention which achieves the above-mentioned object of the present invention is as follows.

That is, a surface layer in which at least one of the average diameter of the constituent fiber, the constituent fiber material and the density is different from each other in the front and back of the intermediate layer through the intermediate layer in which the constituent fibers of the adjacent front and back layers are mixed. It is a laminated nonwoven fabric in which a meltblown nonwoven fabric layer and a back layer meltblown nonwoven fabric layer are laminated.

The method for producing a laminated nonwoven fabric of the present invention is
At least two rows of melt blown jets are jetted while being swung downward in a direction substantially perpendicular to the jetting direction, and jetted so that the melt blown jets of at least two rows overlap and move onto a moving collection surface. A method for producing a laminated nonwoven fabric, which comprises laminating meltblown fibers.

Alternatively, in the method for producing a laminated non-woven fabric according to the present invention, the cross section is triangular, and the polymer is discharged from a melt blow die having a large number of orifices provided substantially at the tips of the triangular shape. In a method for producing a melt-blown nonwoven fabric in which a melt-blown fiber is discharged while being drawn and thinned by a gas by injecting a gas from a pair of gas-injection slits arranged with an opening of an orifice interposed therebetween to collect on a collecting surface. , By causing at least one of the pressures of the gas supplied to the pair of gas injection slits to change, the melt blown jet flow is oscillated downward in a direction substantially perpendicular to the jetting direction, and the melt blown fibers are laminated on the collecting surface. A method for producing a laminated non-woven fabric, comprising:

[0011]

The melt-blown fibers used in the present invention generally have a fiber diameter that can be produced by the melt-blowing method, that is, an average fiber diameter in the range of 0.5 μm to 20 μm. The suitable fiber diameter and its combination are determined according to the purpose of use.

Generally, when used in an air filter, the fibers of the meltblown nonwoven fabric have an average diameter of 1 μm.
Mainly using polypropylene resin in the range of m to 5 μm,
The average diameter of the fibers of the melt-blown nonwoven fabric is determined in consideration of the cleanliness of air after filtering with a filter, the pressure loss during filtration, the service life of the filter, or the like, or melt-blown nonwoven fabrics having different average diameters are laminated and used. However, since a melt-blown nonwoven fabric having a small average diameter of fibers has characteristics of being extremely flexible, it is composed of a nonwoven fabric having a large fiber diameter, for example, a thick fiber having a diameter of about 10 μm, for use in an air filter that requires morphological stability. Work processes such as laminating and bonding non-woven fabrics to give shape retention are required.

On the other hand, when a combination of a small average fiber diameter and a large fiber diameter is selected in the laminated nonwoven fabric of the present invention, fine dust is collected in the nonwoven fabric layer having a small average fiber diameter and a large fiber diameter is obtained. It is possible to provide an excellent laminated non-woven fabric for an air filter, which can retain its shape in the non-woven fabric layer. At this time, according to the knowledge of the present inventors, the difference in average diameter of the meltblown fibers is at least 2.
If it is not μm, the effect of improving the shape-retaining property while maintaining the cleanliness of air after filtration with a filter and the pressure loss during filtration is small, so the difference is preferably 2 μm or more.

In the present invention, the polymer forming the meltblown fiber may be any polymer as long as it can be spun, and various thermoplastic polymers usually used in the meltblown method, for example, polyolefins such as polypropylene and polyethylene, and polyethylene. Polyester such as terephthalate and polybutylene terephthalate, nylon 6
Polyamide such as nylon 66 and nylon, a copolymer thereof, an ethylene / vinyl compound copolymer such as an ethylene / vinyl chloride copolymer, or a styrene resin can be used. These may be used alone or in a mixture. In the laminated non-woven fabric of the present invention, when a combination of a polymer in which different polymers are wettable and a polymer in which they are not wet is used, a surface layer made of hydrophilic fibers and a back surface made of non-hydrophilic fibers are used. And a hydrophilic layer and a non-hydrophilic fiber are mixed in the intermediate layer, or a laminate in which the hydrophilic fiber layer and the non-hydrophilic fiber layer are overlapped in the thickness direction by at least 4 layers or more. A non-woven fabric is manufactured, and it is possible to provide a napkin or a table cloth having a function of absorbing water from one side and impervious to the other side.

Next, a method for producing the laminated nonwoven fabric of the above invention will be described. The laminated non-woven fabric of the present invention is produced by laminating meltblown fibers by repeating or oscillating at least two rows of meltblown jets. That is, the melt blow method is usually a thermoplastic polymer is heated to form a melt, the melt is extruded from a die having a large number of orifices, heating gas consisting of normal air to the extruded melt from the die orifice. It consists of spraying, forming fiberized filaments or fibers, and collecting the melt blown jet stream of the fiber and gas mixed onto a drum or porous belt, so that multiple rows of melt blown jet streams can be fed to the same drum or Even if collected on the porous belt, the second row meltblown fiber layer is formed on the first row meltblown fiber layer, and the third row meltblown fiber layer is formed thereon. , And so on, only a laminated nonwoven having fiber layers corresponding to the number of melt-blown rows is obtained. At least 2 of the present invention
By swaying the melt-blown jet stream of the row and collecting it on the same drum or porous belt, first, the melt-blown fiber layer of the second row is formed on the melt-blown fiber layer of the first row. As described above, the fiber layers in each row of the melt blown are sequentially overlapped, and then by the oscillation of the melt blown jet flow, the fiber layers are folded on the already formed laminated fiber layer in the order in which the laminated fiber layer is turned upside down. Stacked,
Furthermore, the fiber layers of the first and last rows of the melt-blown injection row are the surfaces on one side, and the intermediate layer of the multi-layer structure has a structure in which the fiber layers are folded and laminated in the order in which the top and bottom are inverted again. A laminated nonwoven fabric is formed. In the present invention, the above-mentioned "oscillation" means that a melt-blown jet flow can be swung in a direction substantially perpendicular to the jet direction (movement having a perpendicular direction component). It is an important factor in practicing the present invention that some action is given so as to "swing".

There are no particular restrictions on how to oscillate the melt blown jet flow, but the spinneret orifice and the nozzle for blowing the heating gas are integrated to reciprocate in the moving direction of the drum or porous belt for collecting the melt blown fibers. It may be moved, and the spinneret orifice and the nozzle for blowing the heating gas may be integrated and turned in the direction of movement of the drum or the porous belt for collecting the meltblown fibers. However, the cross-section is triangular, and the polymer is discharged from a die having a large number of orifices provided at the substantially pointed end of the triangle, and the gas is discharged from a pair of gas injection slits that sandwich the orifice opening. In the melt-blowing method of pulling and thinning the polymer by injecting,
A method of swinging the melt blow jet in the moving direction of the drum or the porous belt surface for collecting the melt blow fibers by changing at least one of the pressures of the gas supplied to the pair of gas jet slits is to shake the melt blow jet. It is excellent in that the moving cycle can be set to be short, and the device is simple and has good operability.

In the manufacturing method of the present invention, the intervals of the melt blow jets may be such that the oscillating melt blow jets overlap each other.

Thus, (1) the front surface layer and the back surface layer are made of different average diameters or different polymers, or fibers having different average diameters and polymers.
The intermediate layer has a structure in which the fibers of the front layer and the fibers of the back layer are mixed, and is a laminated nonwoven fabric formed by a melt blow method, (2) different average diameters, or different polymers, or average diameters with each other. Laminated nonwoven fabric formed by a melt blow method having at least 4 or more fiber layers in the thickness direction, which are made of fibers different in Can be manufactured.

The laminated nonwoven fabric of the present invention can also be manufactured by advancing while reciprocating the surface of a drum or a porous belt for collecting meltblown fibers without rocking the meltblown jet flow, but it is also a manufacturing facility. Becomes complicated.

The laminated nonwoven fabric of the present invention may be pressed by an embossing roll or the like depending on the purpose of use, and various processes using a fluid, for example, entanglement of fibers, perforation, or engraving of patterns are performed. May be treated with a chemical agent such as a surfactant, and other materials such as woven and knitted fabrics, non-woven fabrics,
You may use it, combining with a film etc.

Next, the laminated nonwoven fabric of the present invention and the method for producing the same will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an example of the laminated nonwoven fabric of the present invention, in which 1 is a first fiber layer and 2 is a fiber layer.
Indicates a second fiber layer, and 4 indicates a laminated nonwoven fabric. As shown in the figure, the first and second fiber layers are surface meltblown layers (that is, the front and back surfaces), and the intermediate layer is a mixture of the first and second fibers. There is.

FIG. 2 is a schematic sectional view showing another example of the laminated nonwoven fabric of the present invention. In the figure, 1 is a first layer meltblown fiber layer, 2 is a second layer meltblown fiber layer, 3 is a third layer meltblown fiber layer, and 4 is a laminated nonwoven fabric. As shown in the figure, the first layer, the second layer, and the third layer of the fiber layers are folded in an overlapping state to form a laminated nonwoven fabric of four or more fiber layers in the thickness direction.

FIG. 3 is a process chart showing an example of a process for producing the laminated nonwoven fabric of the present invention. In the figure, 4 is the laminated nonwoven fabric of the present invention, 5, 6, and 7 are melt-blowing devices, and 8, 9 and 10 are melt-blowing jet streams. 11 is a porous belt for collecting meltblown fibers,
Reference numeral 12 represents a suction device. The mixed flow of fibers and gas injected from the meltblowing device is oscillated, and is collected and accumulated on the porous belt while being folded in a state where at least two fiber layers are overlapped, and the gas and fibers are separated to form a book. Form the laminated nonwoven of the invention.

FIG. 4 is a schematic cross-sectional view showing an example of the melt blow injection device used for producing the laminated nonwoven fabric of the present invention. In the figure, 13 is an orifice, 14 is a polymer channel, 15 and 16 are independent gas injection slits,
17 and 18 are independent gas supply paths, and 19 and 20
Indicates an independent gas chamber, and 21 indicates a melt blow jet flow. The molten polymer passes through the polymer flow path 14, is discharged from the row of the orifices 14 at the substantially tip end of the triangle, and is discharged from the gas supply paths 17 and 18 through the gas chambers 19 and 20 and the gas injection slits 15 and 16. The melt blown jet stream 21 is a mixture of the jetted gas and the polymer that has been finely drawn into fibers and is drawn and thinned by the gas. At this time, gas supply path 1
By changing the pressures of the gases supplied to 7 and 18, respectively, the pressures of the gas injection slits 15 and 16 can be changed substantially, and the melt blow injection flow 21 generally bends to the slit side where the gas pressure is low. That is, the melt blow jet flow 21 can be oscillated by changing at least one of the pressures of the gas supplied to the pair of gas jet slits 15 and 16.

FIG. 5 is an enlarged view of a schematic cross section showing an example of an orifice and an injection slit portion of a melt blow injection device used for producing the laminated nonwoven fabric of the present invention. 1 in the figure
3 is an orifice, 15 and 16 are gas injection slits, 22
Indicates a slit member, and H indicates the height dimension between the substantial tip of the orifice and the front edge of the slit member. A preferable dimension of H for oscillating the melt blown jet flow by changing at least one of the pressures of the gas supplied to the pair of gas jet slits 15 and 16 is H = −5 to +5 mm, and H = −. The range of 3 to +3 mm is more preferable. If the dimension of H is too large on the minus side, the melt blow jet 2
When the rocking of No. 1 is caused, the polymer sprayed at the tip of the slit easily adheres and becomes dirty, and when the dimension of H becomes excessive on the plus side, the velocity of the gas jetted from the gas jet slits 15 and 16 is attenuated. Since the force for pulling and thinning the polymer discharged from the orifice 13 is reduced, the configuration of the orifice should be taken into consideration with such a point in mind.

[0027]

EXAMPLES Examples of the present invention will be described below.

Example 1 Using the apparatus shown in FIG. 3 equipped with a melt blow injection apparatus having 7 orifices per 1 cm of the mouthpiece width and a gas injection slit gap of 0.3 mm, the melt flow from the first melt blow injection apparatus was used. Melting rate 300 polypropylene resin to 300 ℃
Extruded at a speed of g / hr and pressure 2 on the gas injection slit.
The melt-blown fiber having an average diameter of about 1.5 μm was obtained by drawing with heated air of about 280 ° C. supplied at Kg / cm ² G.
From the second melt blow injection device, polypropylene resin having a melt flow rate of 300 was melted at 280 ° C., extruded at a speed of about 50 g / hr per 1 cm of the die width, and supplied to the gas injection slit at a pressure of 2 Kg / cm ² G about 28 g.
It was pulled by heated air at 0 ° C. to obtain a meltblown fiber having an average diameter of about 2.5 μm. A polypropylene resin having a melt flow rate of 60 is supplied from the third melt blow injection device
Melted at 0 ° C and extruded at a speed of about 40 g / hr per 1 cm width of the die, and pressure was 2 Kg / cm ^{2 at the} gas injection slit.
The melt-blown fiber having an average diameter of about 6 μm was obtained by drawing with heated air of about 280 ° C. supplied in G. Then, the pressure of the heated air supplied to the gas injection slits of the first, second and third melt blow injection devices was adjusted to 0.5 Kg / cm ^2.
The melt blown jet flow is oscillated by changing the range from G to 3.5 Kg / cm ² G,
A nonwoven fabric was obtained by collecting on a porous belt arranged at a distance of cm. This nonwoven fabric had a basis weight of about 120 g / m ² and a thickness of about 5 mm, and was a laminated nonwoven fabric in which at least 15 fiber layers were observed when the cross section was observed. This non-woven fabric could be used as an air filter for trapping about 80% of 0.3 μm polystyrene particles.

Example 2 In the same apparatus as that shown in Example 1, polypropylene resin having a melt flow rate of 300 was melted to 280 ° C. from the first melt blow injection device to obtain about 50 g / hr per 1 cm of the die width. It was extruded at a speed and pulled by heated air of about 280 ° C., which was supplied to the gas injection slit at a pressure of 2 Kg / cm ² G to obtain meltblown fibers having an average diameter of about 2.5 μm. From the second melt blow injection device, a copolymer of polybutylene terephthalate and polyethylene glycol was heated and melted at 320 ° C. to give about 50 g per 1 cm of the die width.
Extruded at a speed of / hr, pressure 2K on the gas injection slit
The melt blown fiber having an average diameter of about 3 μm was obtained by drawing with heated air of about 300 ° C. supplied at g / cm ² G. Next, the pressure of the heated air supplied to the gas injection slits of the first and second melt blow injection devices is set to 0.5 kg /
The non-woven fabric was obtained by oscillating the melt blown jet flow while changing the range from cm ² G to 3.5 Kg / cm ² G, and collecting it on a porous belt placed 50 cm away from the melt blower jet device. This non-woven fabric has a basis weight of about 250 g / cm ² and a thickness of about 10 mm. The surface layer is meltblown fiber made of a copolymer of polybutylene terephthalate and polyethylene glycol, and the back layer is meltblown fiber made of polypropylene. It was a laminated non-woven fabric in which a mixture of multiple fiber layers was observed when the cross section was observed. This non-woven fabric absorbs water from the front surface and retains water, and the back surface has a property that water is unlikely to penetrate therethrough, and thus can be suitably used as an incontinence pad.

[0030]

The present invention has the following excellent effects.

(1) The surface layer and the back surface layer are composed of different average diameters or different polymers, or fibers having different average diameters and polymers, and the intermediate layer is composed of the surface layer fibers and the back surface layer. Mixed with fibers, or
Different average diameters, or different polymers,
Alternatively, a melt blown laminated non-woven fabric comprising fibers having different average diameters and different polymers, which are continuously folded in a state where at least two fiber layers are overlapped with each other and have at least four or more fiber layers in the thickness direction. Since this structure can be adopted, if this laminated non-woven fabric is used for an air filter, it is possible to improve the collection efficiency of fine dust with less passage of fine dust and dramatically improve the shape retention property. .. Further, when used for an incontinence pad, it has water absorbing properties on one side, water hardly penetrates, and retains water over almost the entire area in the thickness direction of the nonwoven fabric, and can be suitably used as an incontinence pad.

(2) According to the manufacturing method of the present invention, it is possible to easily manufacture a peculiar meltblown laminated nonwoven fabric having the above-mentioned effects.

[Brief description of drawings]

FIG. 1 is a cross-sectional model diagram showing an example of a laminated nonwoven fabric of the present invention.

FIG. 2 is a cross-sectional model diagram showing another example of the laminated nonwoven fabric of the present invention.

FIG. 3 is a process drawing showing an example of a manufacturing process of the laminated nonwoven fabric of the present invention.

FIG. 4 is a cross-sectional model view showing an example of a melt-blowing injection device used for manufacturing the laminated nonwoven fabric of the present invention.

FIG. 5 is an enlarged model view of a cross section showing an example of an orifice and an injection slit portion of a melt blow injection device used for manufacturing the laminated nonwoven fabric of the present invention.

[Explanation of Codes] 1: First layer meltblown fiber layer 2: Second layer meltblown fiber layer 3: Third layer meltblown fiber layer 4: Laminated nonwoven fabric 5, 6, 7: Meltblown device 8, 9, 10: Melt blow jet flow 11: Porous belt 12: Suction device 13: Orifice 14: Polymer flow passage 15: Gas injection slit 16: Gas injection slit 17: Gas supply passage 18: Gas supply passage 19: Gas chamber 20: Gas chamber 21 : Melt blow jet 22: Slit member H: Height dimension between the substantial tip of the orifice and the front edge of the slit member

Claims (10)

[Claims] 1. A surface layer in which at least one of the average diameter of the constituent fibers, the constituent fiber material and the density are different from each other in the front and back of the intermediate layer via an intermediate layer in which constituent fibers of adjacent front and back layers are mixed. A laminated non-woven fabric obtained by laminating a melt blown non-woven fabric layer and a back layer melt blown non-woven fabric layer. 2. The laminated nonwoven fabric according to claim 1, wherein the laminated structure has a laminated structure of at least four or more fiber layers in the thickness direction. 3. The average fiber diameter of the constituent fibers of the front layer meltblown nonwoven fabric layer and the back layer meltblown nonwoven fabric layer are different from each other, and the difference is 2 μm or more in average diameter. Item 2. The laminated nonwoven fabric according to item 2. 4. The average basis weight of a single fiber layer of the front layer meltblown nonwoven fabric layer or the back layer meltblown nonwoven fabric layer is 50 g.
/ M ² or less, the laminated nonwoven fabric according to claim 1 or 2. 5. The laminated nonwoven fabric according to claim 1, wherein at least a part of fibers constituting the laminated nonwoven fabric is polypropylene fiber. 6. The laminated non-woven fabric according to claim 1, wherein the combination of constituent fiber materials different from each other is a combination of a wettable polymer and a non-wettable polymer. 7. The laminated non-woven fabric according to claim 6, wherein the combination of constituent fiber materials different from each other is a combination of polypropylene or a copolymer thereof and nylon or a copolymer thereof. 8. The laminated non-woven fabric according to claim 6, wherein the combination of constituent fiber materials different from each other is a combination of polypropylene or a copolymer thereof and a copolymer of polybutylene terephthalate. 9. At least two rows of melt blown jet streams,
It is characterized in that the melt blown fibers are jetted while being swung in a direction substantially perpendicular to the jetting direction, and the melt blown fibers are laminated on the collecting surface that is jetted and moved so that the melt blown jet flows of at least two rows overlap. A method for producing a laminated nonwoven fabric. 10. A pair of cross-sections each having a triangular shape, wherein a polymer is discharged from a melt-blowing spinneret having a large number of orifices provided at the substantially pointed ends of the triangular shape, and the polymer is discharged to sandwich the opening of the orifice. In the method for producing a meltblown non-woven fabric which collects on the collecting surface by discharging meltblown fibers while drawing and thinning the polymer by injecting gas from the gas spraying slit, the gas supplied to the pair of gas spraying slits A method for producing a laminated non-woven fabric, characterized in that melt blown jets are oscillated in a direction substantially perpendicular to the jetting direction by changing at least one of the pressures, and meltblown fibers are laminated on the collecting surface.