JP2586125B2 - Long-fiber nonwoven fabric and its manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous filament (long fiber) nonwoven fabric having a specific structure, made of a specific polyethylene resin and a synthetic resin, and a method for producing the same.

The nonwoven fabric of the present invention has good heat sealing properties, and is used in the field of medical hygiene, general living materials, general industrial materials,
Used in a wide range of fields such as agricultural civil engineering materials.

[Related Art] In recent years, nonwoven fabrics have entered a wide range of fields. However, it is undeniable that various and various processes and conditions are used in the method for producing the nonwoven fabric, and that the product characteristics limited by the processes and conditions impose restrictions on utilization.

For example, in the case of staple nonwoven fabric, various raw materials and
Short fibers with a changed shape can be provided easily, and it can be said that processing into nonwoven fabric is relatively easy with general-purpose fibers,
Since the constituent fibers are short fibers, there are some restrictions in terms of mechanical practical characteristics such as toughness and durability of the product.

In addition, special fibers cannot be easily obtained, and in general, it is difficult to impart unique functions and specific properties due to the high difficulty of the cotton-opening and web-forming steps.

On the other hand, the method of making a nonwoven fabric from continuous filaments is not only an economical manufacturing method because a sheet-like material is made at once from the raw material resin, but also eliminates the difficulty of processing a single fiber, so it can be easily thickened. It has the advantage that it can be made as thin as possible, and efforts have been focused on the development of tough nonwoven fabrics and nonwoven fabrics with special functionality.

In order to industrially produce a nonwoven fabric having such a specific function consisting of such filaments at a low cost, the spunbonding process uses a unique production means over a wide range of processes, and therefore, particularly under high productivity. It is easy to cause problems that affect the basic form of the nonwoven fabric, such as high-speed spinnability and filament opening / dispersibility.

As an invention relating to a problem affecting the basic form of the nonwoven fabric, for example, in a nonwoven fabric made of bimetallic conjugate fiber, for example, as described in JP-B No. 45-2345, imparting bulkiness by expressing crimping, adhesive component Although it has been proposed to provide an adhesive property by a composite, such a method has been put to practical use in a method of forming a web by carding or the like as a short fiber, but in a spunbond nonwoven fabric made of a filament, In general, fibers tend to be bundled and tend to develop shrinkage in the coil state, so they have the desired characteristics,
And there are no products that are practical enough. .

Further, recently, for the purpose of improving the adhesive performance, a fiber using a specific polyethylene has been proposed in JP-A-63-92723, but in the invention proposed in the publication, a fiber such as octene copolymer is used. Although specific polyethylene must be used, and more specifically, practical application in the state of a core-sheath conjugate fiber has been proposed, in order to improve the heat sealing performance of such a core-sheath conjugate fiber, it is necessary to use a sheath. It is necessary to increase the thickness of the components, and the ratio of the core component that governs the main performance of the nonwoven fabric is limited, and as a result, there is a problem that the spinnability is impaired, and the fiber characteristics and the nonwoven fabric characteristics are disadvantageous. .

In particular, in the case of a nonwoven fabric intended to provide heat sealing properties, it is important that the nonwoven fabric constituent fibers be sufficiently opened to individual fibers without agglomeration in order to obtain good heat sealing properties. Becomes

[Problems to be Solved by the Invention] An object of the present invention is to produce a continuous filament nonwoven fabric having good heat sealing properties under economical cost and high productivity in view of the above points. And especially
The continuous filaments of the bimetallic conjugate fiber are well spread into individual filaments without agglomeration, and are very uniform, with good softness and good heat sealing properties. It is an object of the present invention to provide a long-fiber nonwoven fabric and a method for producing the same.

[Means for Solving the Problems] The long-fiber nonwoven fabric of the present invention that achieves the above-mentioned object comprises a fiber-forming thermoplastic polymer component and a polyethylene component having a density of 0.95 or more, and the polyethylene component covers most of the cross-sectional outer periphery. Surrounding, a bimetallic composite structure in which the fiber-forming thermoplastic polymer is exposed on a part of the outer periphery of the cross section,
The fiber-forming thermoplastic polymer component has a substantially circular cross-sectional shape, the polyethylene component has a curved cross-sectional shape, and the two components fit together to have a circular or non-circular cross-section, and A long-fiber nonwoven fabric composed of filament fibers in which at least the polyethylene component accounts for 20% or more and 90% or less of the total cross-sectional area. A long-fiber nonwoven fabric characterized by having a weight of 10 g / m ² to 300 g / m ² or less.

Further, the method for producing a long-fiber nonwoven fabric according to the present invention comprises a bimetal-type composite comprising a fiber-forming thermoplastic polymer and a polyethylene component having a density of 0.95 or more, wherein the fiber-forming thermoplastic polymer component is exposed on a part of the outer periphery of the fiber cross section. Wherein the fiber-forming thermoplastic polymer component has a substantially circular cross-sectional shape, the polyethylene component has a curved cross-sectional shape, and the two components fit together to form a circular cross section or a non-circular cross section. After spinning while drawing the composite filament fibers exhibiting at a speed of 3000 m or more per minute in accordance with the jet air flow, and further, the spun filament fiber bundle is caused to collide with an impingement plate and spread, and then the jet filament group Is collected on the porous moving surface,
Further, there is provided a method for producing a long-fiber nonwoven fabric, which comprises subjecting a group of collected filaments to a heat press treatment at a temperature of 50 ° C to 120 ° C.

[Operation] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings and the like.

FIG. 1 is a process schematic diagram showing one embodiment of the method for producing a long-fiber nonwoven fabric according to the present invention, wherein 1 and 2 are extruder extruders,
The melted polymer from each extruder is filtered through a spin block 3 connected to 2 and a filter / cap pack 4 therein, and then discharged in a filament fiber form from the cap pores. The at least 20 discharge yarns 5 discharged in this manner travel in the atmosphere and are sucked and jetted by an air aspirator 6 installed at a position 20 cm to 200 cm below the base. Then, the jet filament group 7 is caused to collide with the baffle plate 8 to promote the change of the direction of the jet 10 and the improvement of the spreadability and the spreadability.
The jet is preferably a wire mesh conveyor 11 having a suction duct 12 located 10 cm to 100 cm below the baffle 8.
Collected to a web 16 of the desired basis weight of
Downstream, it is pressed and wound by a heated and pressed calender roll 9.

FIG. 2 is a partial cross-sectional view showing a detailed mode of the discharge unit die, which is composed of an upper plate 13 and a lower plate 14, and a fiber-forming thermoplastic polymer component is flowed under pressure from a hole 15 formed in the upper plate. And the polyethylene component passage 17 drilled in the lower plate 14
And to meet. Here, in one embodiment, there is a method in which a gap 18 is provided such that the association portion is directly associated from a part of the lateral direction with respect to the flow direction of the melt from the upper plate 13, or in another embodiment, A method in which a pipe or the like is provided so as to directly join in the flow direction of the melt from the plate may be adopted.

FIG. 3 shows an example of a cross-sectional structure of a fiber used in the present invention. In each of the cross sections, a thermoplastic polymer component other than the ethylene polymerization pair having a fiber forming ability and a polyethylene component having a density of 0.95 or more have a bimetallic composite structure. Polyethylene as used herein refers to an ethylene polymer having a fiber-forming ability.If the density is 0.95 or more, various copolymers or a mixture of some of them, or a degree that does not impair the basic properties of polyethylene A mixture of other organic synthetic polymers or inorganic substances may be used. Preferably, resins in the category generally referred to as linear high-density polyethylene exhibit exceptional effects in multiple aspects such as composite performance, spinning performance, fabric production performance, and product practical characteristics. In this case, it is important that the temperature of the polyethylene component discharged from the mouthpiece has a melting point of at least 20 ° C., preferably 50 ° C. to 140 ° C. higher than the melting point of the polymer.
It is preferable that the temperature is raised up to about ° C., since the spinning instability due to bending in the shape of a letter when discharging from the die is improved. When the temperature is high and the spinning stability for a long time is impaired, it can be reduced or eliminated by adding a known antioxidant, a thermal decomposition inhibitor, etc., and these additions should be considered. Even if such additives are included, they are included in the scope of the present invention.

As the other fiber-forming thermoplastic polymer, any melt-spinnable polymer other than polyethylene can be used. These polymers include polyesters such as polyethylene terephthalate, polyamides such as nylon 6, polyolefins such as polypropylene, sulfur-containing polymers such as polyphenylene sulfide, various thermoplastic elastomers, and various other known polymers and copolymers. It is. It is important that the melting point of these polymers is at least 20 ° C. higher than the melting point of the polyethylene component, and if this condition is not satisfied, the heat sealing performance in the practical stage of nonwoven fabric is somewhat inferior. Particularly when polyethylene terephthalate or a copolymer thereof is used among these polymers, the spinning performance is improved, and surface crystallization during spinning of polyethylene is promoted,
It is suitable because it significantly contributes to the opening performance and is excellent in heat sealing properties.

FIG. 5 is a micrograph (× 30) of the nonwoven fabric. Figure A
Shows that when the polyethylene of the present invention having a density of 0.95 or more is used, the fibers are well opened to individual fibers and the coating performance is excellent. On the other hand, FIG. B shows the case where polyethylene having a density of 0.94 is used, in which the fibers are in a bundled state, lacks covering properties, and have poor physical properties and are impractical.

The shape of the polyethylene component and the other components in the fiber cross section may be circular or non-circular as shown in FIGS. 3A to 3D. In any case, the area ratio of the polyethylene component to the total cross-sectional area is 20%. % Or more and 90% or less is important, and the outer peripheral ratio of polyethylene occupying the cross-sectional outer periphery is not less than the cross-sectional area ratio, more preferably 50% or more and 90%
It is important that the following is occupied, and that the other polymer component is exposed on a part of the outer periphery of the cross section. Within this range,
The filament opening of the constituent filament fiber bundle is excellent, the spinning trouble such as yarn breakage can be reduced or eliminated, and the heat sealing performance can be improved more than expected. It is interesting to note that, particularly preferably, if the polyethylene of FIG. 3A is crescent shaped and the other polymer is circular, the heat sealing performance in practice is very good.

To make a filament with such a structure, the second
Using a die having a shape as shown in the figure, a method of associating, for example, polyester from the upper plate hole and the polyethylene liquid from the gap 18 is preferable, and the discharge strip from the discharge hole 21 does not bend and can withstand high-speed spinning. Things.

The yarn discharged in this manner is preferably drawn and spun with a fluid flow at a speed of at least 3000 m / min with at least 20 filaments together.According to the present invention, the fineness of the filament is from 0.1 denier to 0.1 denier. Web formation can be performed well within a range not exceeding 10 denier. By satisfying the requirements of the present invention, it is possible to form a web in a state in which the bifilamentous composite filament is well opened without being bundled.

FIG. 4 is a schematic view showing an example of the structure of the nonwoven fabric of the present invention, in which a portion 22 which is discretely squashed and bonded over the entire surface of the sheet and an unconstrained portion where fibers are randomly arranged remain It is made up of 23. It is important that the area of the portion 22 is in the range of 0.2 mm ² to 10 mm ² because the drapeability is not impaired, and in order to secure the heat sealing performance, the area does not exceed 50% with respect to the entire area of the sheet, more preferably. Is
It is preferable that the constrained portions 22 be scattered within a range not exceeding 15%. The reason for this is that the composite structure is deformed in the portion already pressed and the flat structure of the polymer component unique to the bimetal composite disappears, so that the contribution to the heat sealing performance is reduced.

Non-woven fabric of the present invention, when formed from a basis weight 10 g / m ² to a thickness of 300 g / m ^2, the field which has been used with conventional nonwoven, of course, especially packaging covering material, filter, wiper acids, sanitation and The present invention is suitable for fields in which medical materials, various molding materials, and sheets in other fields are processed into small articles and used.

Nonwoven fabric of the present invention is easily capable of heat sealing, generally, for example 0.99 ° C., can be sealed with only 1 second to press about 2 seconds during the heating head pressure 2 kg / cm ^2.

It can be particularly emphasized that, compared to a nonwoven fabric made of a core-sheath composite filament using the same composition of polymer, the fact that the seal strength of the heat-sealed product is high by adopting the structure of the present invention has remarkably high industrial value. . In addition to utilizing these heat sealing properties, the product of the present invention has a unique luster and
It has smoothness, electrical properties, and flexibility, and is a material that is effective not only in fields where these properties can be utilized, but also in other fields utilizing physical and chemical properties.

[Examples] Hereinafter, the present invention will be described with reference to examples.

Example 1 Polyethylene (Ace Polyethylene HD, Showa Denko KK) having a melt index of 30 g / 10 minutes as measured by JIS K6760 as one component and polyethylene terephthalate having an intrinsic viscosity of 0.62 measured with an orthochlorophenol solution as another component , Fiber injection was performed by the apparatus shown in FIG. The base used at this time has the structure shown in Fig. 2, the upper plate hole is a circle with a diameter of 2.0mm, the lower plate hole is a circle with a diameter of 0.2mm, the gap is 1mm, and the two components are associated over half the circumference of the hole. It has become. The number of lower plate pores is 66 per die.
Individual. The polyethylene component is extruded at 180.degree. C. and passed through a metering pump to a spin block heated to 280.degree. C., while the polyester component is extruded at a temperature of 280.degree. C. and fed to the same spin block. 33 g / min of both components were supplied from a metering pump to one base. An air aspirator was installed at a position 100 cm below the base. The structure of the aspirator is 8 mm in diameter of the yarn suction port, 8.1 mm in outer diameter of the compressed air jetting annular slit, and a pipe with an inner diameter of 10 mm and a length of 50 cm is connected below it. A collision plate was arranged at a distance of 3 mm from the end of the pipe so as to form an obtuse angle of 30 degrees with the axis of the pipe. In the collision plate, the fiber group spouting from the pipe is 1c
It is structured to be released into the atmosphere after contacting m. With these devices, compressed air at a pressure of 2.5 kg / cm ² G was supplied at 800 Nl / min, and the yarn discharged from the spinneret was sucked into an aspirator and jetted from the outlet.

The resulting fiber has a fineness of 2.25 denier and a spinning speed of 4000 m /
In min, the area ratio of polyethylene to the total cross-sectional area of the filament is 55%, and the perimeter ratio of the polyethylene component to the total cross-sectional perimeter is 80%, which satisfies practically the strength characteristics and heat shrinkage characteristics. there were. The fiber group spouted under these conditions was collected on a wire mesh moving at a position 40 cm below the collision plate. At this time, a suction fan was installed below the collecting position so that the formation of the web on the wire mesh was not disturbed. The web on the running wire mesh was sandwiched at a pressure of 15 kg / cm between embossed rolls having the same temperature as that of a smooth calender roll heated to 110 ° C. and engraved by arranging projections having a diameter of 1 mm and circular flat surfaces at intervals of 5 mm.

The obtained sheet had an elegant luster, had a smooth surface, was rich in flexibility, and had a single fiber that was well opened and uniformly dispersed. In addition, as for the obtained nonwoven fabric, individual filaments were well opened as shown in FIG. 5A, and a practical nonwoven fabric with high uniformity was obtained.

This nonwoven fabric was cut into 5 cm squares, and the weight of each was measured. The average basis weight determined from the data of individual sections is 50 g /
m ² , coefficient of variation was 4%. The sheet thus obtained was subjected to a heat sealing test according to the method of JIS Z-1707. Here, the sealing temperature was 150 ° C., the pressure was 1 kgf / cm ² , and the pressing time was 3 seconds. The obtained value was 3.52 kg / 15 mm, which was suitable for various packaging materials.

Comparative Example Using exactly the same apparatus and conditions as in the example, the sheath component had a density of 0.
916, polyethylene (SHUREX manufactured by Showa Denko KK) having a melt index of 23 g / 10 min. As shown in FIG. 5B, the obtained nonwoven fabric has a single fiber agglomerated and has many unopened portions, and the gap between the fibers lacks conspicuous coatability.
It was extremely non-uniform and the basis weight variation by the above method exceeded 20%.

As a result of measuring the sheet collected in this comparative example under the same conditions, the result was 1.2 kg / 15 mm, and the seal face was easily damaged.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a filament nonwoven fabric with a good openness of single fibers and a high uniformity without particularly changing the equipment and conditions of the fabricating process in a complicated manner. Can be

Such a nonwoven fabric can be easily heat-sealed without using means such as lamination or coating, and it can be said that such a nonwoven fabric can be easily obtained, which is extremely industrially significant. In addition, since the nonwoven fabric has strong processing performance by a simple heat seal, the molding time in practical use is reduced, and it is extremely effective as a clean material for living and industrial materials.

[Brief description of the drawings]

FIG. 1 is a schematic process diagram showing one embodiment of the method for producing a long-fiber nonwoven fabric of the present invention. FIG. 2 is a partial cross-sectional view showing a detailed mode of the discharge unit base. FIG. 3 shows an example of a cross-sectional structure of a fiber used in the present invention. FIG. 4 is a schematic view showing an example of the structure of the nonwoven fabric of the present invention. FIG. 5 is a micrograph (30) showing the fiber shape of the nonwoven fabric.
Times). 1, 2: extruder, 3: spin block, 5: discharge yarn, 6: aspirator, 8: impact plate, 9: calender roll, 10: fiber flow, 11: wire mesh, 13: upper plate, 14: lower plate , 16: web, 21: pore

Claims (4)

(57) [Claims] 1. A fiber-forming thermoplastic polymer component having a density of 0.
A bimetallic composite structure comprising 95 or more polyethylene components, wherein the polyethylene component surrounds most of the outer periphery of the cross-section, and the fiber-forming thermoplastic polymer is exposed on a part of the outer periphery of the cross-section. The component has a substantially circular cross-sectional shape, the polyethylene component has a curved cross-sectional shape, and the two components fit together to form a circular cross section or a non-circular cross section, and at least the total cross-sectional area of the polyethylene component Is a long-fiber nonwoven fabric composed of filament fibers of not less than 20% and not more than 90%, and the constituent filaments are joined to each other by the polyethylene component, and have a basis weight of 10 g / m ² to 300 g / m ²
A long-fiber nonwoven fabric characterized by the following. 2. The long-fiber nonwoven fabric according to claim 1, wherein the fineness of the constituent filament fibers is 0.1 denier or more and 10 denier or less. 3. An embossing process for forming a dot pattern over substantially the entire surface of the nonwoven fabric, wherein the area of one dot of the embossed pattern is not less than 0.2 mm ^{2 and not} more than 10 mm ² , and 2. The long-fiber nonwoven fabric according to claim 1, wherein the ratio of the dot embossed portion to the total is 1 to 30%. 4. A bimetal-type composite structure comprising a fiber-forming thermoplastic polymer and a polyethylene component having a density of 0.95 or more, wherein the fiber-forming thermoplastic polymer component is exposed on a part of the outer periphery of the fiber cross section. The formable thermoplastic polymer component has a substantially circular cross-sectional shape, and the polyethylene component has a curved cross-sectional shape, and the two components are fitted to inject a composite filament fiber having a circular or non-circular cross-section. Spinning while pulling at a speed of 3000 m or more per minute accompanied by an air flow, and further, after spinning the spun filament fiber bundle against an impingement plate and opening the fiber, the jet filament group is placed on a porous moving surface. A method for producing a long-fiber nonwoven fabric, comprising: collecting and subjecting a group of filaments collected to heat to a pressure of 50 ° C. to 120 ° C.