JPH05186954A - Nonwoven fabric excellent in dimensional stability and its production - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven fabric excellent in tensile strength by mixing non-split conjugate filaments with split filaments produced from split type bicomponent conjugate filaments each having a multi-lobar cross-sectional shape and subsequently subjecting the mixture to a fusion treatment. CONSTITUTION:Split filaments A having a single filament of 0.05-1 denier and split filaments B having a single filament fineness of three times or larger that of the filament A, both being produced from split type bicomponent conjugate filaments each having a multi-lobar cross-sectional shape, are mixed with non-split conjugate filaments, and the low melting point split filaments A are melted and solidified to produce fused sites between the mutual non-split conjugate filaments. Each of the split type bicomponent conjugate filaments each is composed of an approximately circular core formed from a polymer B and of at least three lobes which are non-compatible with the polymer B, which are formed from a polymer A having a lower melting point than that of the polymer B and which are bonded to the circumference of the core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is highly flexible and
The present invention relates to a non-woven fabric having excellent dimensional stability and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a non-woven fabric has been known in which various split type two-component composite continuous single yarns are accumulated and then the composite continuous single yarns are split to express ultrafine split filaments. Such a nonwoven fabric is preferable because the constituent fibers are extremely fine filaments (for example, filaments having a denier of 1 denier or less). However, since this non-woven fabric is composed of extremely fine filaments, it has a drawback that the filaments are easily cut when an external force is applied, resulting in poor dimensional stability.

Therefore, it has been proposed to melt and solidify a part of the split filaments to provide a fused portion in the nonwoven fabric (Japanese Patent Application No. 3-29529). However, if the fusion-bonded portions are densely provided, since the fusion-bonded portions are formed into a film to some extent, the flexibility of the obtained nonwoven fabric may decrease. On the contrary, if the space between the fused parts is increased,
The filaments present in the space are easily cut, and the dimensional stability is poor. It is also conceivable to mix a filament having a relatively large fineness with excellent tensile strength together with the split filament. However, it is difficult to uniformly mix the split filaments and the filaments of large fineness, and it is often impossible to obtain a homogeneous nonwoven fabric.

[0004]

From the above,
The inventors of the present invention use a split type bicomponent composite filament having a special multi-leaf cross section, and melt and solidify the low melting point component constituting the core portion to fuse the composite filaments to each other. Further, the composite filament is further divided into a leaf portion and a core portion to develop an ultrafine split filament that constitutes the leaf portion, and at the same time, a split filament having a relatively large fineness that constitutes the core portion. To develop a non-woven fabric by expressing
No. 94 and Japanese Patent Application No. 2-96894). According to this method, the split filament having a relatively large fineness is uniformly mixed with the extra fine split filament, and since the composite long fibers are fused to each other, a high tensile strength and a homogeneous nonwoven fabric are obtained. It is thought to be done. However, in this method, in order to melt and solidify the core portion, when the composite long fibers are fused to each other, the leaves surrounding the core portion interfere with the fusion, and the composite long fibers are fused to each other. It has been difficult to fuse them effectively. That is, there is a drawback in that it is difficult to give sufficient tensile strength to the obtained nonwoven fabric and to give satisfactory dimensional stability.

In view of the above, the present invention uses a split type bicomponent composite filament having a special multi-leaf cross section, and a polymer forming a core portion as a polymer forming a leaf portion. Also adopting a low melting point, by melting and solidifying this leaf portion or the ultrafine split filaments generated by splitting the leaf portion, together with good fusion between the composite long fibers and the like,
A non-woven fabric having excellent tensile strength, in which relatively many fusion points are formed in each composite long fiber and each split filament expressed by splitting of the composite long fibers is uniformly mixed, and its production It is intended to provide a method.

[0006]

That is, according to the present invention, a substantially circular core portion formed of a polymer B and a melting point which is incompatible with the polymer B and has a lower melting point than the polymer B are used. At least 3 formed of polymer A and bonded to the periphery of the core.
Split filaments A having a fineness of 0.05 to 1 denier composed of polymer A, in which split type bicomponent composite filaments having a multi-lobed cross-sectional shape consisting of individual leaves are expressed, and the split filaments. Polymer B, which has a fineness more than 3 times that of A
Which is a non-woven fabric in which split filaments B composed of 1. and the undivided composite long fibers are mixed, and in which the non-divided composite long fibers are separated from each other by melting and solidifying the polymer A. The present invention relates to a non-woven fabric having excellent dimensional stability, which is characterized by the presence of a fused portion that is fused with the same, and a method for producing the same.

First, the split type two-component composite continuous fiber used in the present invention (hereinafter simply referred to as "composite continuous fiber").
Will be described. The composite continuous fiber used when producing the nonwoven fabric according to the present invention is composed of the polymer A and the polymer B incompatible with the polymer A. The incompatibility between the polymer A and the polymer B is to make it easy for both polymers to be split when the composite continuous fiber is impacted.

The polymer A has a lower melting point than the polymer B. Here, when the polymer has no melting point, its softening point is taken as the melting point. This is because the polymer A is melted and solidified and used as a fusion component. In addition,
The difference in melting point between the polymer A and the polymer B is preferably 30 ° C. or higher. The reason for this is that if the difference in melting point is less than 30 ° C., the polymer B may be softened or melted when the polymer A is melted and solidified, and the fiber assembly may be thermally contracted during production. However, it tends to be difficult to obtain the desired size. Furthermore, since the difference in melting point is small, the temperature range during fusion is narrowed, and temperature control tends to be difficult.

Further, the composite long fiber has a multi-lobed cross-sectional shape in which the polymer B forms a core portion and the polymer A forms a leaf portion joined around the core portion. Thus, the reason why the polymer A is arranged on the peripheral surface of the composite long fiber is to further promote fusion between the composite long fibers by the polymer A. Also,
The core has a substantially circular cross-sectional shape. This is because if the core has a non-circular cross-sectional shape, stress concentration is likely to occur when an external force is applied and the core is easily cut. Further, at least three leaf portions are joined around the core portion.
When the number of leaves is less than 3, the fusion points between the composite long fibers due to the polymer A are reduced, and the tensile strength of the resulting nonwoven fabric is not sufficiently improved.

The fineness of the composite filaments satisfying the above conditions is preferably about 2 to 12 denier. When the fineness is less than 2 denier, it tends to be difficult to produce the composite continuous fiber. On the contrary, when the fineness exceeds 12 denier, the fineness of the split filament composed of the polymer A becomes relatively large. Therefore, it becomes difficult to form a non-woven fabric made of ultrafine filaments, which is the object of the present invention. As a specific example of the multifilament cross section composite long fibers, those having a cross section as shown in FIGS. 2 to 4 are preferable. These are polymer A
Is a leaf portion, which is bonded to the periphery of the core portion formed of the polymer B and is exposed on the surface of the composite long fiber. The leaves are joined together in a state of being partitioned from the core into a shape that can be split and split.

In the present invention, a typical example of the combination of the polymer A and the polymer B constituting the composite long fiber is polyolefin / polyester. Particularly, it is preferable to use polyethylene terephthalate as the polyester. This combination gives cross-sectional stability,
This is because the resulting nonwoven fabric is excellent in both strength and flexibility. Polyethylene terephthalate polymer B
In this case, since the spinning temperature is as high as around 300 ° C., the melt index value of polyethylene used as the polymer A is preferably 10 or less. When the melt index value exceeds 10, the melt viscosity of polyethylene becomes low, and during melt composite spinning, polyethylene completely surrounds polyethylene terephthalate,
There is a tendency that it becomes difficult to obtain a composite filament having a multilobe cross section because the cross section becomes a core-sheath type. The melt index value referred to in the present invention is measured by the method described in ASTM D1238 (E).

It is also preferable to use polyethylene as the polymer A and polyamide as the polymer B. This combination is also excellent in cross-sectional stability, strength and flexibility of the resulting nonwoven fabric. In particular, it is preferable to use nylon 6 as the polyamide. Since the spinning temperature of nylon 6 is as high as 270 ° C., it is preferable that the melt index value of polyethylene used as the polymer A is 20 or less. When the melt index value exceeds 20, the melt viscosity of polyethylene becomes low, and during melt composite spinning, polyethylene completely surrounds nylon 6 and the cross section becomes a core-sheath type and has a multi-lobed cross section. It tends to be difficult to obtain fibers.

It is also preferable to use polyamide as the polymer A and polyester as the polymer B. This combination is also excellent in cross-sectional stability, strength and flexibility of the resulting nonwoven fabric. In particular, it is preferable to use nylon 6 as the polyamide and polyethylene terephthalate as the polyester. Note that the combinations described above are merely representative examples, and various other combinations may be arbitrarily adopted.

In the present invention, examples of the polyolefin polymer mainly used as the polymer A include aliphatic α-monoolefins having 2 to 18 carbon atoms, such as ethylene, propylene, butene-1, pentene. There are homopolyolefins or copolymerized polyolefins of -1,3-methylbutene-1, hexene-1, octene-1, dodecene-1, octadecene-1. Aliphatic α-monoolefins are other olefins and / or small amounts (up to about 10% by weight of polymer) of other ethylenically unsaturated monomers such as butadiene, isoprene, pentadiene-1, 3, styrene, α-methyl. It may be copolymerized with a similar ethylenically unsaturated monomer such as styrene. Particularly in the case of polyethylene, those copolymerized with propylene, butene-1, hexene-1, octene-1 or a similar higher α-olefin up to about 10% by weight of the polymer are preferable.

Examples of polyamide polymers usable in the present invention include nylon 4, nylon 46, nylon 6,
Nylon 66, Nylon 610, Nylon 11, Nylon 12, Polymeta-xylene adipamide (MXD-6),
Polyparaxylylene decanamide (PXD-12), polybiscyclohexylmethane decanamide (PCM-1)
2) or a copolyamide having these monomers as constitutional units.

Examples of the polyester polymer which can be used in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid or adipic acid and sebacic acid as acid components. Homo-synthesized from aliphatic dicarboxylic acids or their esters such as and diol compounds such as ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, cyclohexane-1,4-dimethanol as alcohol components Polyester or a copolyester, and paraoxybenzoic acid, 5-sodium sulfoisophthalic acid, polyalkylene glycol, pentaerythritol, bisphenol A or the like may be added or copolymerized to the above polyester.

Examples of other fiber-forming polymers include:
For example, a vinyl polymer is used, and specifically, polyvinyl alcohol, polyvinyl acetate, polyacrylic acid ester, ethylene vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof is used. Moreover, a polyphenylene polymer or a copolymer thereof can also be used.

The polymers A and B include a matting agent, a pigment, a flameproofing agent, a deodorant, and a deodorant within a range that does not impair the object of the present invention.
Arbitrary additives such as antistatic agents, antioxidants, and ultraviolet absorbers may be added.

The composite continuous fiber used in the present invention is generally produced by the following method. That is, it is spun by a conventionally known melt composite spinning method, and is cooled by a blowing wind using a conventionally known cooling device such as horizontal spraying or annular spraying, and then generally, using an air sucker, a target fineness is obtained. It is towed and thinned and taken. The pulling speed is preferably 2000 m / min or more, particularly 3000 m / min or more.

The composite filaments discharged from the air sucker are generally charged and opened by passing through a corona discharge region in a high-voltage field or a frictional collision zone, and then moved like a conveyor comprising a screen. A fiber aggregate can be obtained by opening and accumulating fibers on a deposition device. The basis weight of the fiber assembly is preferably about 10 to 150 g / m ² . When the basis weight of the fiber assembly exceeds 150 g / m ² , the composite continuous fibers cannot be split and split in the middle layer of the fiber assembly when the composite continuous fibers are split and split by the action of the high-pressure liquid film flow. It becomes a tendency. On the other hand, if the basis weight of the fiber assembly is less than 10 g / m ² , it tends to be too thin and it will be difficult to impart sufficient tensile strength and the like to the obtained nonwoven fabric. In the present invention, it is most preferable that the fiber assembly has a basis weight of about 10 to 40 g / m ² .

Heat is applied to a predetermined portion of the thus obtained fiber assembly to melt and solidify only the polymer A,
The composite long fibers are fused together to form a fused portion. The fusion-bonded portion is, for example, using an embossing device composed of a concavo-convex roll and a smooth roll, or an embossing device consisting of a pair of concavo-convex rolls, and heating the concavo-convex roll to press the convex part on the fiber assembly, It can be formed by melting the coalescence A and then allowing it to cool and solidify. On this occasion,
The uneven roll is preferably heated to a temperature equal to or lower than the melting point of the polymer A. When the concavo-convex roll is heated to a temperature higher than the melting point of the polymer A, the polymer A is melted even in a portion other than the convex portion pressed by the fiber assembly, and the area of the fused portion is more than a predetermined ratio. Also, the resulting nonwoven fabric tends to be less flexible. The cross-sectional shape of the convex portion of the concavo-convex roll is round, elliptical, rhombic, triangular, or T-shaped.
Any shape such as a shape or a well shape can be adopted. Further, the fusion-bonded portion may be formed using an ultrasonic welding device. The ultrasonic welding device melts the fiber-forming polymer A by frictional heat between the composite long fibers by irradiating a predetermined portion of the fiber assembly with ultrasonic waves.

The fused portion can be formed in the fiber assembly at a desired ratio, but in the present invention, it is formed at a ratio of 5 to 50% with respect to the total area of the obtained nonwoven fabric. Is preferred. If the fused portion is less than 5% with respect to the total area of the nonwoven fabric, the tensile strength of the nonwoven fabric tends to decrease. On the other hand, when the fusion-bonded portion exceeds 50%, the number of fixed portions such as split filaments increases, and the resulting nonwoven fabric tends to be less flexible.

When the fiber aggregate having the fused portion is subjected to a predetermined splitting treatment, the portion other than the fused portion is
The composite long fibers are divided to develop split filaments A and B. The split filament A is one in which the polymer A forming the leaves of the composite long fibers is divided and expressed. The split filaments B are those in which the leaves are divided and separated from the polymer B forming the core of the composite long fibers. As a method of splitting and splitting, (1) a method of applying a high-pressure liquid film flow and / or a high-pressure liquid columnar flow to the fiber assembly, (2) using the fiber assembly with two sets of rolls having different speeds. Examples of the method include a method in which the compound long fibers are introduced into the space and an elongation force is applied to the composite long fibers, and (3) a method in which the fiber assembly is mechanically bent. Also, besides this,
Divided splitting treatment can be performed by a desired method.

The fineness of the split filament A developed by the split split treatment of the composite long fibers is 0.05 to 1 denier. If the fineness of the split filament A exceeds 1 denier, it means that the resulting nonwoven fabric does not contain ultrafine filaments, and the texture and flexibility of the nonwoven fabric and further delicate surface touch cannot be obtained. Not preferable. To make the fineness of split filament A less than 0.05 denier,
Melt composite spinning becomes difficult, and the productivity of composite long fibers decreases, which is not preferable. On the other hand, the fineness of the split filaments B developed by the split splitting treatment is 3 times or more the fineness of the split filaments A. If the fineness of the split filament B is less than 3 times the fineness of the split filament A, the presence of filaments of relatively large fineness in the non-woven fabric is reduced, and it becomes difficult to impart sufficient tensile strength to the obtained non-woven fabric. Therefore, it is not preferable. In particular, the fineness of the split filament B is 6 to 13 times that of the split filament A.
Most preferably, it is about double. Even if the predetermined splitting treatment is performed, not all the composite long fibers existing in the fiber assembly are split and split, and some may remain in an unsplit state. However, the undivided composite long fibers are uniformly mixed in the nonwoven fabric together with the split filaments A and B, and do not have a great adverse effect on the physical properties of the nonwoven fabric.

In the above-mentioned method, the fusion-bonded portion is formed on the fiber assembly, and then the split fiber treatment is performed. In the present invention, however, the fiber assembly is subjected to the split fiber treatment and then melted. You may form a wearing part. In this case, the split filament A, the split filament B, and the undivided composite filament are separated from each other by melting and solidifying the split filament A and melting and solidifying the leaves of the composite filament that remain undivided. Are fused together. In the present invention, the melt solidification of the split filament A and the melt solidification of the leaves of the composite filaments are both melt solidification of the polymer A, so both are collectively referred to as the melt solidification of the polymer A. There is.

Preferred embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to this method. FIG. 1 is a process chart illustrating one embodiment of a method for producing a nonwoven fabric having excellent dimensional stability according to the present invention. The spinning device has individual melt extrusion / measurement units 1 and 2 for polymer A and polymer B. The weighed both polymers are composited by the spinneret 3 and spun as a large number of composite long fiber groups 4. At this time, as shown in FIGS. 2 to 4, the discharge hole of the spinneret 3 is formed by polymer B forming a core portion and polymer A forming a leaf portion and being bonded to the periphery of the core portion. Moreover, it is selected so as to obtain a composite continuous fiber in which the polymer A is partitioned from the polymer B into a shape capable of being divided and split within the cross section of the composite continuous fiber. Further, the discharge amount of the polymer A is selected so that the fineness of the split filament A after the split splitting is 0.05 to 1 denier, and the discharge amount of the polymer B is the fineness of the split filament B. It is selected so that the fineness of the fine filament A is three times or more.

The discharged composite long fiber group 4 is cooled by a cooling device 5, and then taken by a take-up means composed of an air sucker 6, and then from a screen through a corona discharge fiber opener 7 in a high piezoelectric field. The fibers are accumulated and spread on the moving and depositing device 8 to be a fibrous aggregate 9. In the fiber assembly 9, the composite filament fiber group 4 is partially heat-sealed by the melting and solidification of the polymer A by the embossing device provided with the heated concavo-convex roll 10 to form the spot-shaped fused portion.

Next, the fibrous assembly having the fused portion formed thereon is supported by the screen 11, water is applied by the water applying device 12, and then the split fiber splitting is performed by the liquid flow ejected from the high pressure liquid flow processing device 13. And, if desired, undergo a confounding process. Then, the liquid flow is discharged by the vacuum suction device 15. The nonwoven fabric obtained by the splitting and splitting treatment is squeezed by a mangle roll 16, passed through a drying / heat treatment device 17, and then wound up as a product roll 18. Although FIG. 1 shows an example in which the splitting and splitting process is performed using a liquid flow, for example, as shown in FIG. 5, a supply roll 20 and a surface velocity higher than the surface velocity of the supply roll 20 are used. It is also possible to introduce a fiber assembly having a fusion-bonded portion between the drawing rolls 21 and give a stretching force to the composite long fibers for split splitting. In this case, since the liquid flow is not used, the drying step or the like is unnecessary, and the product roll 18 is immediately wound up after the split fiber division.

As described above, a non-woven fabric containing the ultrafine split filament A and the split filament B thicker than the split filament A can be obtained. Then, in this non-woven fabric, due to the solidification of the polymer A, the fused portions where the composite filaments were fused or the split filaments A, B and the undivided composite filaments were fused together. It has a fused part. Such a non-woven fabric can be used for various purposes as it is or by adding a slight amount of a binder, a finishing agent and the like as desired.

[0030]

EXAMPLES The evaluation methods for the physical properties described in the examples are as follows. (A) Melting point of polymer: The temperature giving the maximum value of the melting endothermic peak measured at a temperature rising rate of 20 ° C./min using a DSC-2 type differential scanning calorimeter manufactured by Perkin Elmer was taken as the melting point. (B) Melt index value of polymer: ASTM D1238 (E)
It was measured by the method described in. (C) Tensile strength of non-woven fabric: In accordance with the strip method described in JIS L-1096, prepare 10 test pieces with a width of 5 cm and a length of 10 cm,
Each maximum tensile strength was measured under the conditions of a tensile speed of 10 cm / min, and the average value was taken as the tensile strength. (D) Tensile elongation of non-woven fabric: Elongation at break measured by the same method as in (b). (E) Total hand of non-woven fabric: This shows flexibility and was measured with a slot width of 1 cm according to the handle ometer method of JIS L-1096. (F) Bulk density of nonwoven fabric: Calculated by the following formula from the thickness value and the basis weight value measured by a thickness meter (load 5 g / cm ² ). Bulk density (g / cm ³ ) = Basis weight (g / m ² ) / [Thickness (m
m) × 1000] (g) Denier: The denier after split splitting was obtained by calculating the cross-sectional area from the shape and dimensions in an electron micrograph and correcting the density.

Example 1 As the polymer A, polyethylene having a melting point of 132 ° C. and a melt index value of 8 g / 10 min was used, and as the polymer B, a melting point of 258 ° C., phenol: tetrachloroethane =
Polyethylene terephthalate having an intrinsic viscosity [η] = 0.7 obtained by measuring at 20 ° C. in a 1: 1 mixed solvent was used. Then, using a multi-leaf cross-section composite spinneret having a long-fiber cross-section as shown in Fig. 3 and a total number of divisions of 7, the composite ratio of polyethylene and polyethylene terephthalate was set to 1: 1, and the melting temperature of polyethylene was 230 ° C. Polyethylene terephthalate was melt-extruded at a melting temperature of 285 ° C., single hole discharge rate = 1.2 g / min (polyethylene = 0.6 g / min, polyethylene terephthalate = 0.6 g / min). The composite continuous fiber thus obtained has polyethylene terephthalate as a core and is made of polyethylene around the core.
The leaves were joined together.

Then, the composite long fiber group was cooled by a cooling device, and then taken up at a speed of 4500 m / min by a plurality of air suckers arranged 120 cm below the spinneret,
The fibers were opened by a corona discharge fiber-opening device, and the composite long fibers were deposited on a moving wire mesh deposition device to obtain a fiber assembly having a basis weight of 50 g / m ² . The fineness of the composite continuous single yarn collected from the fiber assembly was about 2.5 denier.

This fiber assembly was introduced into the embossing device without being wound up. With this embossing device, the total area of the convex parts arranged in a dotted pattern is 15% of the total area of the roll.
, And the convex-concave roll is heated to a temperature of 125 ° C. By this embossing device, the polymer A in the composite long fiber constituting the fiber assembly is
The (leaf portion made of polyethylene) is melted and solidified, and the portion pressed by the convex portion becomes the fused portion.

Then, the fiber assembly was introduced onto a 78-mesh screen moving at a speed of 10 m / min, water was applied by a water application device, and then the fiber assembly was subjected to a high-pressure water flow to obtain a composite length. The fiber was split and split. The high-pressure water stream has a group of injection holes with a hole diameter of 0.12 mm, a number of holes of 600, and a hole pitch of 0.6 mm.
It was ejected from a high-pressure water columnar flow treatment device having three rows. The injection hole is located 80 mm above the fiber assembly, and a high-pressure water stream is ejected from the injection hole at a water pressure of 80 kg / cm ² . This high-pressure water stream has 3
Circulated. As a result, the composite long fibers were split and entangled, and polyethylene split filaments and polyethylene terephthalate split filaments were developed, and the filaments were entangled with each other. The polyethylene split filament had a fineness of 0.2 denier and the polyethylene terephthalate split filament had a fineness of 1.2 denier.

Then, squeeze the water with a mangle roll,
Treated with a drying / heat treatment device kept in an atmosphere of 98 ° C,
A non-woven fabric having excellent dimensional stability was obtained. This non-woven fabric having excellent dimensional stability contained polyethylene split filaments, polyethylene terephthalate split filaments, which were formed by splitting the composite filaments, and undivided composite filaments. In addition, the fused portion formed first did not change until the end, and the composite filaments remained fused due to the melting and solidification of the polymer A (the leaf portion made of polyethylene). Various physical properties of the nonwoven fabric excellent in dimensional stability obtained as described above are as shown in Table 1.

[Table 1]

Comparative Example The polyethylene terephthalate used in Example 1 was used as the polymer A, and the polyethylene used in Example 1 was used as the polymer B. And, except that the melting temperature of polyethylene is 230 ° C., the melting temperature of nylon 6 is 265 ° C., and the take-up speed by air sucker is 4600 m / min.
A nonwoven fabric was obtained in the same manner as in Example 1. At this time, the composite long fiber had polyethylene as a core, and six leaf parts made of polyethylene terephthalate were joined around the core. The resulting non-woven fabric contained polyethylene terephthalate split filaments having a fineness of 0.2 denier, polyethylene split filaments having a fineness of 1.2 denier, and undivided composite continuous fibers, which were developed by splitting the composite long fibers. Further, the first fusion-bonded portion remained unchanged until the end, and the composite long fibers remained fused together due to the solidification of the polymer B (core made of polyethylene). The various physical properties of the nonwoven fabric obtained as described above are as shown in Table 1.

As is apparent from the comparison between the non-woven fabric obtained by the method according to Example 1 and having excellent dimensional stability, and the non-woven fabric obtained by the method according to the comparative example, the former non-woven fabric is superior in longitudinal strength and width. Excellent strength. This is because when the composite long fibers were fused with the polymer A (polyethylene) forming the leaves as in the example, the polymer B forming the core as in the comparative example. It is considered that this is because more fusion points are formed between the individual composite long fibers in the fusion site than in the case of fusion with (polyethylene).
Further, the former nonwoven fabric has a smaller total hand value and is more flexible. It is considered that this is because the leaf portions having a small fineness are fused and the degree of freedom of the split filament B, which originally lacks flexibility, is not easily hindered. For example, it is considered that when the core portion having a large fineness is fused, the flexibility of the split filament B, which originally lacks flexibility, is further diminished, and as a result, the flexibility is greatly reduced.

Example 2 In place of the multi-lobe cross-section composite spinneret used in Example 1, a multi-lobe cross-section composite spinneret having a long fiber cross section as shown in FIG. Further, a nonwoven fabric excellent in dimensional stability was obtained in the same manner as in Example 1 except that the take-up speed by air sucker was changed from 4500 m / min to 4300 m / min. At this time, the obtained composite long fibers had polyethylene terephthalate as a core, and 12 leaf parts made of polyethylene were bonded around the core. The resulting non-woven fabric was one in which composite filaments were expressed by being split, polyethylene split filaments having a fineness of 0.1 denier, polyethylene terephthalate split filaments having a fineness of 1.3 denier, and undivided composite filaments. .. In addition, the fused portion formed first did not change until the end, and the composite filaments remained fused due to the melting and solidification of the polymer A (the leaf portion made of polyethylene). Various physical properties of the nonwoven fabric excellent in dimensional stability obtained as described above are as shown in Table 1.

Example 3 As polymer A, polyethylene having a melting point of 132 ° C. and a melt index value of 15 g / 10 min was used, and as polymer B, a melting point of 225 ° C., relative to 96% sulfuric acid measured at 25 ° C. viscosity
2.56 nylon 6 was used. Then, a nonwoven fabric excellent in dimensional stability was obtained in the same manner as in Example 1 except that the melting temperature of polyethylene was 230 ° C., the melting temperature of nylon 6 was 265 ° C., and the take-up speed by air sucker was 4000 m / min. At this time, the obtained composite continuous fiber has nylon 6 as a core and polyethylene around the core.
It consisted of 6 leaves joined together. The obtained non-woven fabric contained polyethylene split filaments having a fineness of 0.2 denier, nylon 60 split filaments having a fineness of 1.4 denier, in which the composite continuous fibers were developed, and undivided composite continuous fibers. In addition, the fused portion formed first did not change until the end, and the composite filaments remained fused due to the melting and solidification of the polymer A (the leaf portion made of polyethylene). Various physical properties of the nonwoven fabric excellent in dimensional stability obtained as described above are as shown in Table 1.

Example 4 As the polymer A, the nylon 6 used in Example 3 was used, and as the polymer B, the polyethylene terephthalate used in Example 1 was used. Then, the melting temperature of both polymers was set to 285 ° C, and the take-up speed by air sucker was set to 4
A nonwoven fabric excellent in dimensional stability was obtained in the same manner as in Example 1 except that the rate was 000 m / min. At this time, the obtained composite long fibers have polyethylene terephthalate as the core,
Six leaf parts made of nylon 6 were joined around the core part. The resulting non-woven fabric contained nylon 60% split filaments having a fineness of 0.2 denier, polyethylene terephthalate split filaments having a fineness of 1.4 denier, which were developed by splitting the composite long fibers, and undivided composite long fibers. In addition, the fused portion formed first did not change until the end, and the composite filaments remained fused due to the melting and solidification of the polymer A (the leaf portion made of nylon 6). Various physical properties of the nonwoven fabric excellent in dimensional stability obtained as described above are as shown in Table 1.

Example 5 The fiber assembly having the fusion-bonded portion obtained in Example 1 was, without being wound, a supply roll at room temperature rotating at a surface speed of 10 m / min and a room temperature rotating at a surface speed of 14 m / min. It was introduced into the drawing roll and was stretched 1.4 times to obtain a nonwoven fabric excellent in dimensional stability. This non-woven fabric contained polyethylene split filaments having a fineness of about 0.1 denier, polyethylene terephthalate split filaments having a fineness of about 0.9 denier, which were developed by splitting the composite long fibers, and undivided composite long fibers. In addition, the fused portion formed first did not change until the end, and the composite filaments remained fused due to the melting and solidification of the polymer A (the leaf portion made of polyethylene). Various physical properties of the nonwoven fabric excellent in dimensional stability obtained as described above are as shown in Table 1.

[0042]

As described above, the nonwoven fabric according to the present invention contains the ultrafine split filament A and the split filament B thicker than the split filament A. The non-woven fabric according to the present invention is provided with the fusion-bonded portion that is fused by the solidification of the polymer A constituting the leaf portion of the composite long fiber. This fusion-bonded portion is fusion-bonded between the composite filaments or between the split filaments A, B and the undivided composite filaments. Therefore,
The non-woven fabric contains thick split filament B,
Moreover, since each of the composite filaments and the like has a large number of microscopic fusion points due to the fine polymer A, the mechanical properties such as tensile strength are excellent. It has the effect of being excellent in stability. Further, since the core having a large fineness is not melted and solidified, the split filament B having a relatively large fineness has a freedom of movement, and the flexibility of the non-woven fabric caused by the extra fine split filament A is unlikely to be hindered. It is effective.

Since the non-woven fabric having excellent dimensional stability according to the present invention described above has excellent mechanical properties and flexibility, it is used as a bag material, a bag material such as an envelope, a wiping cloth, an air filter and general industry. It can be suitably used as various filters for use.

[Brief description of drawings]

FIG. 1 is a process schematic view showing an embodiment of a method for producing a nonwoven fabric excellent in dimensional stability according to the present invention.

FIG. 2 is a schematic view showing an example of a cross section of a split type bicomponent composite continuous fiber having a multi-lobed cross section used in the present invention.

FIG. 3 is a schematic view showing an example of a transverse cross section of a split type bicomponent composite continuous fiber having a multilobe cross section shape used in the present invention.

FIG. 4 is a schematic view showing an example of a cross section of a split type bicomponent composite filament having a multilobe cross-section used in the present invention.

FIG. 5 is a schematic view showing an example of a split splitting treatment step used in the present invention.

[Explanation of symbols]

 4 Split-type two-component composite long fiber with multi-leaf cross section 9 Fiber assembly 10 Concavo-convex roll

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasuhiro Yonezawa 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Laboratory

Claims (11)

[Claims] 1. A substantially circular core formed of polymer B,
A polymer A which is incompatible with the polymer B and has a melting point lower than that of the polymer B, is bonded to the periphery of the core, and is composed of at least three leaves. A split filament A having a fineness of 0.05 to 1 denier, which is formed by splitting a split bicomponent composite continuous fiber having a leaf cross-sectional shape, and a fineness of 3 times or more of the fineness of the split filament A. Split filament B composed of polymer B with fineness
And a non-divided composite long fiber mixed together, wherein the non-woven fabric is melted and solidified by the polymer A,
A non-woven fabric having excellent dimensional stability, characterized in that there is a fused portion where the undivided composite long fibers are fused to each other. 2. A substantially circular core formed of polymer B,
A polymer A which is incompatible with the polymer B and has a melting point lower than that of the polymer B, is bonded to the periphery of the core, and is composed of at least three leaves. The split type bicomponent composite long fibers having a leaf cross-sectional shape are opened and accumulated to obtain a fiber assembly, and heat is applied to a predetermined portion of the fiber assembly to melt and solidify only the polymer A to form the composite. After forming a fused portion by fusing the long fibers with each other, the composite long fibers are split and split to develop split filaments A having a fineness of 0.05 to 1 denier composed of the polymer A. A method for producing a non-woven fabric having excellent dimensional stability, which comprises developing a split filament B composed of the polymer B having a fineness three times that of the split filament A. 3. A substantially circular core formed of polymer B,
A polymer A which is incompatible with the polymer B and has a melting point lower than that of the polymer B, is bonded to the periphery of the core, and is composed of at least three leaves. A split filament A having a fineness of 0.05 to 1 denier, which is formed by splitting a split bicomponent composite continuous fiber having a leaf cross-sectional shape, and a fineness of 3 times or more of the fineness of the split filament A. Split filament B composed of polymer B with fineness
And a non-divided composite long fiber mixed together, wherein the non-woven fabric is melted and solidified by the polymer A,
A nonwoven fabric having excellent dimensional stability, characterized in that there is a fusion-bonded portion where the split filaments A, split filaments B, and the undivided composite filaments are fused together. 4. A substantially circular core formed of the polymer B,
A polymer A which is incompatible with the polymer B and has a melting point lower than that of the polymer B, is bonded to the periphery of the core, and is composed of at least three leaves. A split type two-component system composite long fiber having a leaf cross-sectional shape is opened and collected to obtain a fiber assembly, and then the composite long fiber is split and split to have a fineness of 0.05 to 1 denier composed of the polymer A. After expressing the split filaments A and expressing the split filaments B composed of the polymer B having a fineness three times that of the split filaments A, a predetermined part of the fiber assembly is obtained. Heat is applied to the polymer A to melt and solidify only the polymer A, and the split filament A, the split filament B, and the composite continuous fiber are fused to each other to form a fused portion. A method for producing a non-woven fabric having excellent dimensional stability. 5. The nonwoven fabric excellent in dimensional stability according to claim 1 or 3, wherein the total area of the fused portion is 5 to 50% of the nonwoven fabric area. 6. The nonwoven fabric excellent in dimensional stability according to claim 1 or 3, wherein the polymer A is a polyolefin and the polymer B is a polyester. 7. The nonwoven fabric excellent in dimensional stability according to claim 1, wherein the polymer A is a polyolefin and the polymer B is a polyamide. 8. Polymer A is a polyamide and polymer B is a polymer.
The non-woven fabric excellent in dimensional stability according to claim 1 or 3, wherein is a polyester. 9. The method for producing a nonwoven fabric excellent in dimensional stability according to claim 2, wherein the melting point difference between the polymer A and the polymer B is 30 ° C. or more. 10. The non-woven fabric excellent in dimensional stability according to claim 2 or 4, wherein an embossing device provided with a concavo-convex roll heated to a temperature equal to or lower than the melting point of the polymer A is used when forming the fused portion. Production method. 11. The method for producing a nonwoven fabric having excellent dimensional stability according to claim 2 or 4, wherein an ultrasonic welding device is used when forming the fused portion.