JPH05186946A - Production of nonwoven fabric from ultra-fine fiber - Google Patents

Abstract

PURPOSE:To produce nonwoven fabric having excellent flexibility. CONSTITUTION:A first, side-by-side type bicomponent conjugated continuous single filament is prepared. The conjugated continuous single filament is composed of a fiber-forming polymer A and another fiber-forming polymer B incompatible with polymer A. The melting point of polymer A is 30 to 180 deg.C lower than that of polymer B. The conjugated continuous single filaments are accumulated and heat is applied to prescribed positions in the accumulation. Thus, the polymer A is melt-solidified to fuse the continuous single filaments each other thereby a fused position is formed. The resultant nonwoven fabric sheet is elongated so that the equation: 1+0.001E<ST<1+0.01E is satisfied where E is the maximum tensile elongation in %, ST represents elongation ratio of the nonwoven sheet. The elongation causes filament division into filaments A and B at the fused points to give nonwoven fabric where these filaments do not substantially cause three-dimensional entanglement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a nonwoven fabric made of ultrafine fibers, which is excellent in flexibility.

[0002]

2. Description of the Related Art Conventionally, there is known a non-woven fabric obtained by accumulating various split type two-component type composite continuous single yarns and then dividing the composite continuous single yarns to express ultrafine split fibers.
Such a non-woven fabric has extremely fine constituent fibers (for example, about
Since it is 1 denier or less), it is excellent in flexibility and is preferable. As a method of dividing the composite continuous single yarn to develop the split fiber, after accumulating the composite continuous single yarn, needle punching this aggregate,
A method of dividing the composite continuous single yarn by impacting with a needle, a method of applying a drug to the aggregate to dissolve and remove one component in the composite continuous single yarn, and a method of applying a high-pressure liquid columnar flow to the aggregate. A method is known in which a columnar flow is applied to give a split.

However, the above method or method cannot apply an impact by a needle or a high-pressure liquid columnar flow to all parts of the composite continuous single yarn, and the degree of splitting is low. Therefore, there is a drawback in that a relatively large amount of the composite continuous single yarns that are not partially divided remain in the nonwoven fabric, and the amount of the ultrafine split fibers is small, so that only the one lacking in flexibility is obtained. Furthermore, the energy of the needles or the high-pressure liquid columnar flow causes the composite continuous single yarns to move and entangle with each other three-dimensionally, and the resulting nonwoven fabric is densified.
It also had the drawback of lacking flexibility. In addition, the method (1) has a drawback that a manufacturing method is complicated because it requires a step of applying a drug and a step of removing a dissolved component, and further requires measures such as recovery of the drug and pollution-free.

[0004]

Therefore, the inventors of the present invention apply a high-pressure film-like flow to a fiber assembly obtained by accumulating split-type two-component composite continuous single yarns to obtain almost all composite continuous single yarns. The invention proposed that the composite continuous single yarn is divided at a high rate by impacting on (Japanese Patent Application No. 3-29529). The present invention has been made for the same purpose as the present invention, and instead of using a high-pressure membranous flow, by applying an extension force to a split type bicomponent composite continuous single yarn under certain specific conditions, It is intended to satisfactorily divide and split a composite continuous single yarn.

[0005]

That is, the present invention has a fiber-forming polymer A and a melting point which is incompatible with the polymer A and which is 30 to 180 ° C. higher than the melting point of the polymer A. A split type two-component type composite continuous single yarn composed of the fiber-forming polymer B and having a fineness of 2 to 12 denier is opened and accumulated to obtain a fiber aggregate.
The polymer A is heated by applying heat to a predetermined portion of the fiber assembly.
After melting and solidifying only the composite continuous single yarns, the composite continuous single yarns are fused to each other to form a fused portion to obtain a non-woven sheet, and then the non-woven sheet is stretched at a stretch ratio satisfying the following formula. The composite continuous single yarn positioned other than the fused portion is split at a predetermined splitting ratio to develop the ultrafine splitting fibers A composed of the polymer A and to be composed of the polymer B. The present invention relates to a method for producing a nonwoven fabric made of ultrafine fibers, which is characterized in that the obtained ultrafine split fibers B are expressed, and the split fibers A and the split fibers B are not substantially three-dimensionally entangled. Note 1 + 0.001E <ST <1 + 0.01E (where, E represents the maximum tensile elongation (%) of the nonwoven sheet, and ST represents the elongation ratio of the nonwoven sheet. ]

First, the split type two-component composite continuous single yarn (hereinafter simply referred to as "composite continuous single yarn") used in the present invention will be described. The composite continuous single yarn used in producing the nonwoven fabric according to the present invention satisfies the following conditions. That is, it is composed of the fiber-forming polymer A and the fiber-forming polymer B which is incompatible with the polymer A. Polymer A and Polymer B are incompatible
This is because both polymers are easily divided when a deformation stress is applied to the composite continuous single yarn.

The fineness of the single yarn is 2 to 12 denier. When the fineness is less than 2 denier, it becomes difficult to produce a composite continuous single yarn. On the contrary, when the fineness exceeds 12 denier, the fineness of the fiber composed of the polymer A or the polymer B becomes relatively large. Therefore, it becomes difficult to form a non-woven fabric made of ultrafine fibers, which is the object of the present invention.

The melting point of the fiber-forming polymer A is 30 to 180 ° C. lower than that of the fiber-forming polymer B. here,
If the polymer has no melting point, its softening point is taken as the melting point. The fiber-forming polymer A melts and solidifies at the fusion-bonding site of the nonwoven sheet, while the fiber-forming polymer B does not melt-solidify at the fusion-bonding site.
Therefore, the melting point difference as described above is set.
When the difference in melting point between the two polymers is less than 30 ° C., when the polymer A is melted and solidified, the polymer B shrinks or deteriorates, so that the dimensional stability of the obtained nonwoven sheet becomes poor. If the melting point difference is less than 30 ° C., it becomes difficult to control the temperature when forming the fused portion. When the difference in melting point exceeds 180 ° C, it becomes practically difficult to produce a composite continuous single yarn. That is,
During the production of single yarn (during melt spinning), the polymer A may be thermally deteriorated. In the present invention, the particularly preferable difference between the melting points of both polymers is 35 to 165 ° C.

The composite continuous single yarn used in the present invention satisfies the above conditions. As a specific example of the composite continuous single yarn, one having a cross section as shown in FIGS. 2 to 5 is preferable. Both of the components of the polymer A and the polymer B are exposed on the surface of the single yarn, and one component is partitioned by the other component into a splittable shape in the cross section of the single yarn. Is what

In the present invention, as the combination of the polymer A and the polymer B constituting the composite continuous single yarn, polyolefin / polyamide, polyolefin / polyester,
Polyamide / polyester, etc. are mentioned, but these are representative examples, and various other combinations are also arbitrarily adopted.

Examples of the fiber-forming polyolefin type polymer which can be used in the present invention include aliphatic α-monoolefins having 2 to 18 carbon atoms, such as ethylene, propylene, butene-1, pentene-1, There are homo- or co-polyolefins of 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. Especially for polyethylene, about 10% by weight of the polymer weight
Up to propylene, butene-1, hexene-1, octene-1
Alternatively, those copolymerized with a similar higher α-olefin are preferable.

Examples of the fiber-forming polyamide polymer that can be used in the present invention include nylon 4, nylon 46, nylon 6, nylon 66, nylon 610 and nylon 1.
1, nylon 12 and polymeta-xylene adipamide (MX
D-6), polyparaxylylene decanamide (PXD-
12), polybiscyclohexylmethane decanamide (PCM-12) or a copolyamide having these monomers as constitutional units.

Examples of the fiber-forming polyester polymer which can be used in the present invention include terephthalic acid as an acid component,
Aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid or aliphatic dicarboxylic acids such as adipic acid and sebacic acid or their esters, and ethylene glycol, diethylene glycol, 1.4 as alcohol components -A homopolyester or a copolyester synthesized from a diol compound such as butanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, etc., wherein paraoxybenzoic acid and 5-sodiumsulfoisophthale are added to the polyester. acid,
Polyalkylene glycol, pentaerythritol, bisphenol A, etc. may be added or copolymerized.

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 fiber-forming polymers A and B include a matting agent, a pigment, a flameproofing agent, a deodorant, an antistatic agent, an antioxidant, and an ultraviolet absorbing agent as long as the object of the present invention is not impaired. Any additive such as an agent may be added.

The composite continuous single yarn 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. Towing speed is over 2000m / min,
Particularly, 3000 m / min or more is suitable. A composite continuous single yarn discharged from an air sucker is generally a moving and depositing device such as a conveyor composed of a screen after being charged and opened by passing through a corona discharge region in a high-voltage field or a frictional collision zone. A fiber aggregate can be obtained by opening and accumulating the fibers. The basis weight of the fiber assembly is preferably about 10 to 150 g / m ² . Particularly, it is most preferable that the basis weight of the fiber assembly is about 10 to 40 g / m ² .

Heat is applied to a predetermined portion of this fiber assembly. Then, the fiber-forming polymer A is melted and solidified, and the composite continuous single yarns are fused to each other to form a fused portion to obtain a nonwoven sheet. At this time, only the fiber-forming polymer A of the composite continuous single yarn is melted and solidified. When the fiber-forming polymer B is also melted and solidified, holes are opened in the fusion-bonded portion to deteriorate the appearance, or the film is completely formed into a film and the flexibility is lowered, which is not preferable.

For such a fusion-bonded portion, for example, 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 is used, and the concavo-convex roll is heated so that the fibrous aggregate is projected. It can be formed by pressing a portion to melt the fiber-forming polymer A and then allowing it to cool and solidify. At this time, it is preferable that the uneven roll is heated to a temperature equal to or lower than the melting point of the fiber-forming polymer A. When the concavo-convex roll is heated to a temperature higher than the melting point of the fiber-forming polymer A, the fiber-forming polymer A is melted even in the parts other than the convex part pressed by the fiber assembly, and The area is more than the given percentage,
There is a tendency that the flexibility of the resulting nonwoven fabric is reduced. The convex section of the concavo-convex roll may have any cross-sectional shape such as a round shape, an elliptical shape, a rhombus, a triangle, a T shape, and a square shape. Further, the fusion-bonded portion may be formed using an ultrasonic welding device. The ultrasonic welding device melts the fiber-forming polymer A by irradiating a predetermined part of the fiber assembly with ultrasonic waves by frictional heat between the composite continuous single yarns and the like.

The fused portion can be formed in a desired ratio in the non-woven sheet, but in the present invention, it is preferably 5 to 40% of the total area of the non-woven sheet. If the fusion-bonded portion is less than 5% with respect to the total area of the nonwoven sheet, the resulting nonwoven fabric tends to have a reduced tensile strength. On the other hand, when the fusion-bonded portion exceeds 40%, the number of the fixed portions of the continuous composite single yarn is increased, and the obtained nonwoven fabric tends to be less flexible.

The non-woven sheet obtained as described above,
The extension treatment is performed under predetermined conditions to divide the composite continuous single yarn at a predetermined splitting ratio. This stretching process is performed so that the stretching ratio of the non-woven sheet satisfies the following equation. That is, 1+
Perform so that the formula 0.001E <ST <1 + 0.01E is satisfied. Where E is the maximum tensile elongation (%) of the non-woven sheet
Represents. The maximum tensile elongation (%) is calculated by the following method according to the strip method described in JIS L-1096. That is, 10 test pieces made of a non-woven sheet having a width of 5 cm and a sample length of 10 cm were prepared, a tensile test was performed under a condition of a tensile speed of 10 cm / min, and the elongation at the time of breaking the test piece was calculated, and the average value thereof was calculated. Was defined as the maximum tensile elongation (%). However, the test piece of the non-woven sheet is such that the longitudinal direction is the machine direction of the non-woven sheet. ST represents the stretch ratio of the nonwoven sheet.
The elongation ratio means, when the length of the nonwoven sheet stretched in the machine direction is 1 when the nonwoven sheet is stretched, and the length before the stretching is l ₀ , the stretch ratio = (L + l ₀ ) /
It is calculated by l ₀ . When the above stretch ratio (ST) is 1 + 0.01E or more when the nonwoven sheet is stretched, the composite continuous single yarn itself may be broken or fractured.
Alternatively, the fusion-bonded portion is broken, and the non-woven sheet is easily cut, which is not preferable. Conversely, the elongation ratio (ST) is 1
If the value is + 0.001E or less, sufficient deformation stress cannot be applied to the composite continuous single yarn, and as a result, the difference due to the difference in deformation stress applied to the polymer A and the polymer B is less likely to occur, and the composite It is not preferable because it is difficult to split and split the continuous single yarn.

As a typical method for stretching the nonwoven sheet, for example, a supply roll rotating at a constant peripheral speed,
There is a method in which a non-woven sheet is introduced between a stretching roll that rotates at a peripheral speed higher than that of the supply roll and the non-woven sheet is stretched between the supply roll and the stretching roll. On this occasion,
The surface temperature of the supply roll and the drawing roll may be room temperature or may be heated. Further, one (one pair) or two (two pairs) or more stretching rolls may be provided in the processing direction of the non-woven sheet. When the stretching ratio is relatively large, for example, two stretching rolls (two pairs) are provided, the first pair of stretching rolls treats the film with a certain stretching ratio, and the second pair of stretching rolls finally finishes. It is preferable to treat so as to obtain the elongation ratio of.

By the stretching treatment for the non-woven sheet, the composite continuous single yarns existing in the non-fused portion of the non-woven sheet are split and split. Then, the split fibers cause the split fibers A made of the polymer A and the split fibers B made of the polymer B to appear. Therefore, the fineness of the split fibers A and B is a fraction of the fineness of the composite continuous single yarn, and is a so-called ultrafine fiber. In particular,
Both of the split fibers A and B preferably have a fineness of 0.05 to 1.0 denier. The fineness of split fibers A and B is 0.05
To obtain a denier of 1.0 to 1.0, the fineness of the polymers A and B partitioned into a dividable shape in the composite continuous single yarn is 0.05 to 1.
It should be 0 denier. The fineness of the polymers A and B is
When the composite continuous single yarn is subjected to melt composite spinning, it can be arbitrarily determined by the hole diameter of the spinning hole, the discharge amount, and the like. It is generally difficult to carry out melt composite spinning with the fineness of the polymers A and B being less than 0.05 denier. If the fineness of the split fibers A, B exceeds 1.0 denier, the split fibers A,
The rigidity of B tends to increase, and the intended soft nonwoven fabric tends not to be obtained. By the stretching treatment, all the composite continuous single yarns existing in a portion other than the fusion-bonded portion of the non-woven sheet are rarely split and split, and a certain amount of undivided composite continuous single yarns remains. It is common.

Further, the developed split fibers A and B do not substantially three-dimensionally entangle with each other due to the elongation treatment in the present invention. The reason for this is that the extension force is simply applied to the composite continuous single yarn, and no force is applied to move the composite continuous single yarn in a random direction. For example, there is a method in which a high-pressure liquid stream is applied to a non-woven sheet and the composite continuous single yarn is impacted to split and split. In this method, the composite continuous single yarn moves in a random direction by the high-pressure liquid flow. However, the composite continuous single yarn and the split fiber are substantially three-dimensionally entangled with each other. Therefore, the nonwoven fabric obtained by the method according to the present invention is not substantially three-dimensionally entangled between the split fibers A, B, etc. Therefore, it is possible to prevent a decrease in the flexibility of the nonwoven fabric due to the entanglement. It is possible. In addition,
The term "substantially three-dimensionally entangled" as used herein means a close entanglement that occurs when treated with a needle punch or a high-pressure columnar flow, and entanglement due to bending of fibers or the like is substantially three-dimensionally entangled. I don't say.

Preferred embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to this method, and appropriate modifications such as dividing the process into a plurality of steps can be made.
FIG. 1 is a process diagram illustrating one embodiment of a method for producing a nonwoven fabric made of ultrafine fibers according to the present invention. The fiber-forming polymer A and the fiber-forming polymer B are individually charged into the raw material hoppers 1 and 2 and melt-extruded by the extruders 3 and 4. Then, the composite spinneret 8 is extruded by the measuring units 5 and 6 and placed in the spin block 7.
And are spun into a large number of composite continuous single yarn groups 9. At this time, the discharge holes of the spinneret 8 have both polymers A and B exposed on the surface of the single yarn as illustrated in FIGS. It is selected so that a single yarn is obtained in which the coalescence is partitioned by the other polymer into split-splittable shapes. In addition, both polymers A,
The discharge amount of B is selected so that the fineness of the split filaments A and B after split splitting is about 0.05 to 1.0 denier.

The discharged composite continuous single yarn group 9 is cooled by the cooling device 1.
After being cooled by 0, it is taken up by a take-up means consisting of an air sucker 11 and then opened onto a moving and depositing device 13 consisting of a screen through a corona discharge opener 12 in a high-voltage field to collect fibers. Become body 14. In the fibrous assembly 14, the composite continuous single yarn group 9 is partially heat-sealed by melting and solidification of the polymer A by an embossing device composed of the heated concavo-convex roll 15 and the flat roll 16, and the dot-shaped fused portion is formed. It is formed.

Next, the non-woven sheet 17 on which the fused portions are formed is introduced into the supply roll 18 and the stretching roll 19. At this time, a stretching treatment is performed between the supply roll 18 and the stretching roll 19, and the composite continuous single yarn existing in a portion other than the fusion-bonded portion of the non-woven sheet 17 is split and split to obtain split fibers A and B. It manifests. Obtained as described above,
The non-woven fabric made of extra fine split fibers is wound up as the product roll 20.

As described above, the fusion-bonded portions where the composite continuous single yarns are fused to each other by melting and solidification of the polymer A, and the split continuous splitting of the composite continuous single yarns at the portions other than this fusion-bonded portion are developed. It is possible to obtain a non-woven fabric having a portion where the split fibers A and B are deposited without substantially three-dimensionally interlacing. 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.

[0028]

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 (c). (E) Bulk density of nonwoven fabric: Calculated from the thickness value measured by a thickness meter (load: 5 g / cm ² ) and the basis weight value. (F) Compressive stiffness of non-woven fabric: Prepare five sample pieces with a sample width of 5 cm and a sample length of 10 cm, bend each sample piece in the longitudinal direction, and join both ends to create a cylindrical sample. did. And, using Toyo Baldwin's Tensilon UTM-4-1-100, this cylindrical sample was compressed in the height direction at a compression rate of 5 cm / min, and the stress at the maximum load was measured. The average value was defined as the compression stiffness. (G) Denier: The denier after splitting and dividing was calculated by calculating the cross-sectional area from the shape dimension 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 of 20 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 composite spinneret in which the cross section of the composite continuous single yarn is as shown in FIG. 3 and the total number of divisions is 12, the composite ratio of polyethylene and polyethylene terephthalate is 1: 1.4, and the melting temperature of polyethylene is 230 ° C. Polyethylene terephthalate was melt-extruded at a melting temperature of 285 ° C., single hole discharge amount = 1.2 g / min (polyethylene = 0.5 g / min, polyethylene terephthalate = 0.7 g / min).

After that, the spun yarn is cooled by a cooling device, then taken out at a speed of 4500 m / min by a plurality of air suckers arranged 140 cm below the spinneret, and opened by a corona discharge opener. Then, the composite continuous single yarn was deposited on a moving wire mesh deposition device to obtain a fiber assembly having a basis weight of 60 g / m ² . The fineness of the composite continuous single yarn collected from the fiber assembly was about 2.0 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. The embossing device melts and solidifies the polymer A in the composite continuous single yarn forming the fiber assembly, and the portion pressed by the convex portion becomes the fusion-bonded portion. By the above method, a non-woven sheet having a fused portion was obtained. The maximum tensile elongation E (%) of this nonwoven sheet was 58%.

This non-woven sheet was introduced into the elongation treatment step without being wound up. The stretching treatment was performed between the pair of supply rolls and the pair of stretching rolls. Both the supply roll and the drawing roll are composed of a pair of a metal roll having a flat surface and a rubber roll having a nip mechanism. Also, the linear pressure between the metal roll and the rubber roll is 15 kg.
/ Cm, and the surface temperature of the roll was room temperature. Then, the peripheral speed of the supply roll was set to 20 m / min, and the stretching treatment was performed so that the stretching ratio with the stretching roll was 1.25.
By this elongation treatment, the composite continuous single yarn in the part other than the fusion-bonded part was split and split, and polyethylene split fibers having a fineness of 0.15 denier and polyethylene terephthalate split fibers having a fineness of 0.20 denier were developed.

The non-woven fabric obtained as described above has a fused portion between the composite continuous single yarns which is fused and solidified by the melting and solidification of the polymer A, and the polyethylene split fiber is present in the portion other than the fused portion. And polyethylene terephthalate split fibers are accumulated without substantially three-dimensional entanglement. The non-woven fabric was provided with a certain amount of strength by the fusion-bonded portion, and the portions other than the fusion-bonded portion were made of extra fine split fibers, and thus were excellent in flexibility and bulkiness.
The various physical properties of this non-woven fabric were as shown below. The longitudinal tensile strength or the longitudinal tensile elongation means the tensile strength or the tensile elongation in the machine direction of the nonwoven fabric. Unit weight: 52 g / m ² Longitudinal tensile strength: 19.8 kg / 5 cm Longitudinal tensile elongation: 52% Bulk density: 0.103 g / cm ³ Compressive bending resistance: 88 g

Comparative Example 1 A nonwoven fabric was obtained under the same conditions as in Example 1 except that the stretch ratio of the nonwoven sheet was 1.01. The composite continuous single yarn in the area other than the fused area of this nonwoven fabric was not sufficiently split and split. Therefore, this nonwoven fabric was inferior in flexibility and bulkiness. The various physical properties of this non-woven fabric were as shown below. Unit weight: 63 g / m ² Longitudinal tensile strength: 20.6 kg / 5 cm Longitudinal tensile elongation: 57% Bulk density: 0.196 g / cm ³ Compressive bending resistance: 158 g

Comparative Example 2 A non-woven fabric was obtained under the same conditions as in Example 1 except that the stretch ratio of the nonwoven sheet was 1.9. However, the nonwoven sheet was cut during the stretching treatment, and the processing operability was remarkably inferior, so that the nonwoven fabric could not be continuously produced.

Example 2 The polyethylene used in Example 1 was used as the polymer A, and the polyethylene terephthalate used in Example 1 was used as the polymer B. Then, using a composite spinneret in which the composite continuous single yarn has a total number of divisions of 7 in a form as shown in FIG. 5, polyethylene forms a core portion and polyethylene terephthalate forms a leaf portion. The composite ratio of polyethylene and polyethylene terephthalate is 1: 1.4, the melting temperature of polyethylene is 230 ° C, the melting temperature of polyethylene terephthalate is 285 ° C, single hole discharge rate = 1.2 g / min (polyethylene =
0.5 g / min, polyethylene terephthalate = 0.7 g / min)
Was melt extruded.

After that, the spun yarn is cooled by a cooling device, then taken out at a speed of 4700 m / min by a plurality of air suckers arranged 170 cm below the spinneret and opened by a corona discharge opener. Then, the composite continuous single yarn was deposited on a moving wire mesh deposition device to obtain a fiber assembly having a basis weight of 65 g / m ² . The fineness of the composite continuous single yarn collected from the fiber assembly was about 2.0 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 portion has a concavo-convex roll heated to 128 ° C. The embossing device melts and solidifies the polymer A in the composite continuous single yarn forming the fiber assembly, and the portion pressed by the convex portion becomes the fusion-bonded portion. By the above method, a non-woven sheet having a fused portion was obtained. The maximum tensile elongation E (%) of this non-woven sheet was 66%. Then, this nonwoven sheet was subjected to a stretching treatment in the same manner as in Example 1 except that the stretching ratio was 1.30, to obtain a nonwoven fabric.

The non-woven fabric obtained as described above has a fused portion between the composite continuous single yarns which is fused and solidified by the melting and solidification of the polymer A, and at the portion other than the fused portion, the fineness is
0.82 denier polyethylene split fibers and 0.19 denier polyethylene terephthalate split fibers are accumulated without substantially three-dimensional entanglement. This non-woven fabric is provided with a certain amount of strength by the fusion-bonded part, and the parts other than the fusion-bonded part are made of extra fine split fibers,
It was rich in flexibility and bulkiness. The various physical properties of this non-woven fabric were as shown below. Unit weight: 54g / m ² Longitudinal tensile strength: 21.7kg / 5cm Longitudinal tensile elongation: 56% Bulk density: 0.118g / cm ³ Compressive bending resistance: 93g

Example 3 As the polymer A, nylon 6 having a relative viscosity of 2.56 measured at a melting point of 225 ° C. and 96% sulfuric acid at 25 ° C. was used, and as the polymer B, the polyethylene terephthalate used in Example 1 was used. Then, using a composite spinneret in which the composite continuous single yarn has a total number of divisions of 7 in the form shown in FIG. 5, nylon 6 forms the core part and polyethylene terephthalate forms the leaf part. The composite ratio of nylon 6 and polyethylene terephthalate is 1: 1.2, the melting temperature of nylon 6 is 265 ° C, the melting temperature of polyethylene terephthalate is 285 ° C, the single hole discharge rate is 1.2 g / min (nylon 6 = 0.55 g / min, polyethylene terephthalate). = 0.65 g / min).

After that, the spun yarn is cooled by a cooling device, then taken out at a speed of 4300 m / min by a plurality of air suckers arranged 120 cm below the spinneret, and opened by a corona discharge opener. Then, the composite continuous single yarn was deposited on a moving wire mesh deposition device to obtain a fiber assembly having a basis weight of 60 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 a convex-concave roll having a convex portion heated to 200 ° C. The embossing device melts and solidifies the polymer A in the composite continuous single yarn forming the fiber assembly, and the portion pressed by the convex portion becomes the fusion-bonded portion. By the above method, a non-woven sheet having a fused portion was obtained. The maximum tensile elongation E (%) of this non-woven sheet was 52%. Then, this nonwoven sheet was subjected to a stretching treatment in the same manner as in Example 1 except that the stretching ratio was 1.20 to obtain a nonwoven fabric.

The non-woven fabric obtained as described above has a fusion-bonded portion between the composite continuous single yarns which is fused and solidified by melting and solidification of the polymer A, and the fineness is observed in the portions other than the fusion-bonded portion.
1.06 denier nylon 60% split fibers and 0.21 denier polyethylene terephthalate split fibers are accumulated without substantially three-dimensional entanglement. This non-woven fabric is provided with a certain amount of strength by the fusion-bonded part, and the parts other than the fusion-bonded part are made of extra fine split fibers,
It was rich in flexibility and bulkiness. The various physical properties of this non-woven fabric were as shown below. Unit weight: 51 g / m ² Longitudinal tensile strength: 22.4 kg / 5 cm Longitudinal tensile elongation: 46% Bulk density: 0.121 g / cm ³ Compressive bending resistance: 99 g

Example 4 A non-woven sheet was obtained under the same conditions as in Example 1, and the non-woven sheet was once wound up by a winding machine. Then, the film was rewound and the expansion process was performed under the same conditions as in Example 1 except that the expansion ratio was 1.29. The various physical properties of this nonwoven fabric were as follows. Unit weight: 49g / m ² Longitudinal tensile strength: 20.1kg / 5cm Longitudinal tensile elongation: 51% Bulk density: 0.101g / cm ³ Compressive bending resistance: 90g

[0045]

As described above, in the method for producing a nonwoven fabric made of ultrafine fibers according to the present invention, heat is applied to a predetermined part of a fiber assembly made of a specific split type bicomponent composite continuous single yarn. Then, a fusion-bonded portion is provided, and then a stretching process is performed under a specific condition to split and split the composite continuous single yarn existing in a portion other than the fusion-bonded portion. Since the stretching treatment only gives a stretching force to the composite continuous single yarn, the split fibers A and B generated by the split split fibers do not substantially three-dimensionally entangle. Therefore, according to this method, it is possible to obtain a non-woven fabric having a high flexibility, which is less likely to cause a decrease in flexibility due to three-dimensional entanglement. In addition, since the fusion-bonded portion is formed, it has an effect of being excellent in mechanical properties such as tensile strength.

Since the nonwoven fabric made of the ultrafine fibers obtained by the method according to the present invention described above has excellent flexibility and mechanical properties, it is used as a bag material, a bag material such as an envelope, a wiping cloth, and an air bag. It can be suitably used as a filter or various filters for general industry.

[Brief description of drawings]

FIG. 1 is a process schematic view showing an embodiment of a method for producing a nonwoven fabric made of ultrafine fibers according to the present invention.

FIG. 2 is a schematic view showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

FIG. 3 is a schematic diagram showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

FIG. 4 is a schematic view showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

[Explanation of symbols]

 9 split type two component type composite continuous single yarn 14 fiber assembly 15 uneven roll 17 non-woven sheet 18 supply roll 19 drawing roll

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[Procedure amendment]

[Submission date] November 26, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a process schematic view showing an embodiment of a method for producing a nonwoven fabric made of ultrafine fibers according to the present invention.

FIG. 2 is a schematic view showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

FIG. 3 is a schematic diagram showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

FIG. 4 is a schematic view showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

FIG. 5 is a schematic view showing an example of a cross section of a split type two-component composite continuous single yarn used in the present invention.

[Explanation of Codes] 9 Split-type Two-component Composite Continuous Single Yarn 14 Fiber Aggregate 15 Uneven Roll 17 Nonwoven Sheet 18 Supply Roll 19 Stretching Roll

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

Claims (4)

[Claims] 1. A fineness comprising a fiber-forming polymer A and a fiber-forming polymer B which is incompatible with the polymer A and has a melting point 30 to 180 ° C. higher than the melting point of the polymer A. 2 to
A 12 denier split type two-component composite continuous single yarn is 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. After the composite continuous single yarns are fused to each other to form a fused portion to obtain a non-woven sheet, the non-woven sheet is subjected to an extension treatment at an extension ratio satisfying the following formula, and other than the fused portion The composite continuous monofilament located at 1 is divided at a predetermined splitting ratio to develop the ultrafine splitting fibers A composed of the polymer A, and at the same time, the ultrafine splitting fibers composed of the polymer B. A method for producing a nonwoven fabric made of ultrafine fibers, characterized in that B is expressed and the split fibers A and the split fibers B are not substantially three-dimensionally entangled. Note 1 + 0.001E <ST <1 + 0.01E (where, E represents the maximum tensile elongation (%) of the nonwoven sheet, and ST represents the elongation ratio of the nonwoven sheet. ] 2. A supply roll rotating at a constant peripheral speed,
A non-woven sheet is introduced between a stretching roll that rotates at a peripheral speed higher than that of the supply roll and a stretching treatment is performed.
A method for producing a non-woven fabric comprising the described ultrafine fibers. 3. The method for producing a non-woven fabric made of ultrafine fibers according to claim 1, 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. .. 4. The method for producing a flexible nonwoven fabric according to claim 1, wherein an ultrasonic welding device is used when forming the fused portion.