JP2000129538A - Divided type conjugate fiber, and nonwoven fabric composed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a divided type conjugate fiber composed of at least two types of fiber-forming polymers incompatible with each other, which is not divided during the nonwoven fabric production stage but easily divided during the processing stage to give a nonwoven fabric of high wiping characteristics, by making its section take a specific shape. SOLUTION: This divided type conjugate fiber is composed of two types of fiber-forming polymers A and B incompatible with each other, e.g. polyester- based and polyolefin-based polymers, wherein the polymer A accounts for at least 85% of the exposed fiber surface, and these polymers form at least 8 segments alternately arranged and extending in the radial direction in the fiber section. It is preferable to form a nonwoven fabric by the fibers, each having the polymer A accounting for 100% of the exposed surface, (d/r) ratio of 0.1 or less [(d): minimum thickness of the polymer A in the fiber section, and (r): fiber radius), and segment fineness of 0.4 deniers or less. It is also preferable to use very fine fibers, composed of the polymer A and/or polymer B formed by dividing the conjugate fibers for producing a nonwoven fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a conjugate fiber having a uniform fiber cross-sectional shape and excellent splitting properties, and an ultrafine fiber obtained by splitting and splitting the split-type conjugate fiber, thereby providing a soft texture. The present invention relates to a nonwoven fabric having a medical hygiene material and wiping.

[0002]

2. Description of the Related Art Conventionally, various splittable conjugate fibers have been proposed in order to obtain a nonwoven fabric having good flexibility and texture.

[0003] Japanese Patent Publication No. 43-7411 and Japanese Patent Laid-Open No.
No. 246336 discloses two kinds of polymers,
It has been proposed to obtain a sea-island composite fiber comprising a sea component and an island component, and to obtain the island component as an ultrafine fiber by removing the sea component. However, the method using sea-island composite fibers is
There is a problem that a complicated manufacturing process such as a spinning process, a woven fabric process, and a fiber dissolving and removing process is required.

In Japanese Patent Application Laid-Open No. 5-321018, split-type composite fibers in which two or more incompatible components are bonded to each other are formed into a web by a dry method or a wet method.
A method has been proposed in which fibers are divided and entangled by a mechanical impact such as a high-pressure water stream or a needle punch to obtain a microfiber nonwoven fabric, and a microfiber nonwoven fabric can be obtained relatively easily. However, while these splittable conjugate fibers need to be easily split by receiving a mechanical impact, if a mechanical crimp is to be applied, the fibers will be separated and split, resulting in a nep or dropping in the web making process. There is a problem that it causes deterioration of the card passing property such as frequent occurrence of cotton.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the splittable conjugate fiber and the nonwoven fabric made of the same,
By setting the fiber cross-sectional form of the splittable conjugate fiber to a specific form, the splittable conjugate fiber is not split at the stage of forming the nonwoven fabric, and the splitting is easily performed for the first time in the splitting process, and excellent flexibility and Split type composite fiber that has a texture and can obtain a nonwoven fabric with high wiping performance,
And a nonwoven fabric comprising the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve such a problem, and as a result, in the cross section of the fiber of the splittable conjugate fiber, one polymer was exposed to the fiber surface. The inventors have found that the object can be achieved by setting the rate in a specific range, and have reached the present invention. That is, the gist of the present invention is as follows. (1) A splittable conjugate fiber composed of two types of fiber-forming polymers (A) and (B) which are incompatible with each other, wherein the exposure rate of the polymer (A) to the fiber surface is 85% or more. In a fiber cross section, a splittable conjugate fiber characterized in that both polymers are radially alternately arranged in a total of eight or more segments. (2) A nonwoven fabric characterized by being composed of ultrafine fibers composed of the polymer (A) and / or the polymer (B) developed by dividing the splittable conjugate fiber.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The splittable conjugate fiber of the present invention needs to be composed of two types of fiber-forming polymers that are incompatible with each other. 2
The species of the fiber-forming polymers are incompatible with each other in order to make it easy to be split when a splittable conjugate fiber is impacted. In the fiber splitting process, splitting failure occurs in the splitting process, and a desired ultrafine fiber cannot be obtained, and a nonwoven fabric made of the fiber has poor texture, softness, and the like.

Examples of the two incompatible fiber-forming polymers include a combination of a polyester-based polymer and a polyolefin-based polymer, and a combination of a polyester-based polymer and a polyamide-based polymer. However, it is not limited to these. Particularly preferred are polyester-based polymers and polyolefin-based polymers, or polyester-based polymers and polyamide-based polymers.

As the polyester-based polymer, it is preferable that the main repeating unit is ethylene terephthalate, propylene terephthalate, butylene terephthalate or ethylene naphthalate, and as long as the effects of the present invention are not impaired, 1,4-butanediol is used. Diol components such as 1,6-hexanediol, bisphenol A
Aromatic diol components such as ethylene oxide adducts of
Addition of copolymers of aliphatic dicarboxylic acid components such as adipic acid and sebacic acid, aromatic dicarboxylic acid components such as isophthalic acid, and stabilizers, fluorescent agents, pigments, antibacterial agents, deodorants, reinforcing agents, etc. What was done.

Examples of the polyolefin polymer include aliphatic α-monoolefins having 2 to 18 carbon atoms, for example, ethylene, propylene, butene-1, pentene-1,3.
-Homopolyolefins or copolymerized polyolefins of -methylbutene-1, hexene-1, octene-1, dodecene-1, and octadecene-1. Aliphatic α-monoolefins may be other olefins or small amounts (up to about 10% by weight of polymer weight) of other ethylenically unsaturated polymers such as butadiene, isoprene, pentadiene-
Similar ethylenically unsaturated monomers such as 1,3, styrene and α-methylstyrene may be copolymerized. Particularly in the case of polyethylene, propylene, butene-1, hexene-1, octene-1 can be used up to about 10% by weight of the polymer.
Those copolymerized with one or similar higher α-olefins are preferred.

As the polyamide, nylon 4, nylon 6, nylon 6,6, nylon 7, nylon 6,1
0, nylon 11, nylon 12, polyamides from bis (p-aminocyclohexyl) methane and 1,10-decamethylenedicarboxylic acid or 1,9-nonamethylenedicarboxylic acid, and less than 15 mol% of a third
Examples thereof include those obtained by copolymerizing components, and copolymers or mixtures of two or more of these.

The cross section of the splittable conjugate fiber of the present invention is such that two kinds of polymers are radially arranged alternately in a total of 8 or more segments, and the exposure rate of one polymer (A) to the fiber surface is 85%.
That is all.

If the number of segments is less than 8, the fineness of the splittable conjugate fiber must be reduced in order to reduce the fineness of the ultrafine fiber that appears after splitting. It is not preferable because it is difficult to obtain a cross-sectional shape and a problem easily occurs in spinning operation. Regarding the upper limit of the number of segments, there is an advantage that as the number is larger, the fineness after division becomes smaller. However, when the number is too large, individual segment forms tend to be hard to be uniform. It is preferable that the length is about a segment.

The exposure rate of one polymer (A) to the fiber surface must be 85% or more. Here, the exposure ratio refers to the ratio of the total arc length of the portion of the polymer (A) exposed on the fiber surface to the total circumferential length of the fiber cross section. If the exposure rate is less than 85%, in the mechanical crimping step of short fibers or the web making step of spreading short fibers through a carding machine, the composite fibers are separated and separated when a mechanical impact is applied. Nep and cotton fall occur, and the card passing property is deteriorated, which is not preferable.

Furthermore, in order to perform splitting more efficiently in the split splitting step, the other polymer (B) is not exposed to the fiber surface, and the polymer (B) is a polymer (A). In a state of being covered thinly, that is, the rate of exposure of the polymer (A) to the fiber surface is 100%, and the ratio of the minimum thickness (d) of the polymer (A) to the fiber radius (r) ( d / r) is preferably 0.1 or less. When (d / r) is larger than 0.1, the thickness of the polymer covering the fiber surface is large, so that in the split splitting step, split splitting becomes difficult to occur easily, which causes poor splitting. The ultrafine fibers intended by the invention are not expressed, and a nonwoven fabric made of the fibers has poor flexibility and wiping properties.

FIG. 1 is a cross-sectional view showing an example of the splittable conjugate fiber of the present invention. One polymer (A) and the other polymer (B) are radially and alternately arranged. (B) is not exposed to the fiber surface, the exposure rate of the polymer (A) to the fiber surface is 100%, and the ratio of the minimum thickness (d) of the polymer (A) to the fiber radius (r) ( d / r) is 0.1 or less,
This is an example in which the total number of segments is 20.

In the present invention, in the cross section of the splittable conjugate fiber, in a state where two kinds of polymers are alternately arranged, the exposure rate of the other polymer to the fiber surface is limited to a small amount, preferably By covering the entire fiber surface with one polymer,
In the fiber manufacturing process and the web forming process, splitting was not performed, but the splitting occurred only for the first time due to the impact in the splitting process, and ultrafine fibers were developed.

The fineness of each segment comprising the two polymers constituting the splittable conjugate fiber of the present invention is preferably 0.1.
The density is preferably 4 denier or less, more preferably 0.3 denier or less. The splittable conjugate fiber is split at the interface between segments made of a polymer by impact, and one polymer (A)
And / or at least ultrafine fibers composed of the other polymer (B), and the fineness of this segment is 0.4.
If it exceeds denier, the Young's modulus of the resulting ultrafine fibers becomes large, and it is difficult to impart the flexibility and texture desired by the present invention to the nonwoven fabric composed of the ultrafine fibers developed by dividing the splittable conjugate fiber of the present invention.

The single yarn fineness of the splittable conjugate fiber is preferably 1 to 12 denier. If the single yarn fineness is less than 1 denier, the desired cross-sectional form is difficult to obtain, and the discharge amount per single hole of the spinneret at the time of melt spinning tends to decrease, and the production amount tends to decrease. If the number of holes in the spinneret is increased to improve the production, the spinning process becomes unstable. If the single yarn fineness exceeds 12 denier, it tends to be difficult to cool the melt-spun yarn or take it off by air soccer, and to reduce the number of holes in the spinneret to promote cooling of the yarn. , The production volume decreases. Furthermore, since it is necessary to form a cross section having more than 30 segments, a complicated spinning device is required.

The splittable conjugate fiber of the present invention is generally produced by the following method. That is, it is spun by a conventionally known melt composite spinning method, cooled by a blowing air using a conventionally known cooling device such as a horizontal spraying or an annular spraying, and then applied with an oil agent, and then taken out through a take-off roller. It is wound on a winder as a drawn yarn. Pickup roller speed is 500m / min ~ 2
000 m / min. A plurality of wound undrawn yarns are drawn and aligned, and drawn between roller groups having different peripheral speeds by a known drawing machine. Next, the drawn tow is crimped by a press-type crimping device, and then cut into a predetermined fiber length to obtain short fibers. The heat setting may be performed at a temperature lower than the melting point of the constituent polymer of the stretched tow depending on the required use.

Next, a nonwoven fabric obtained by using the splittable conjugate fiber of the present invention will be described. First, the splittable conjugate fiber is opened in a carding process to form a web. The obtained web is subjected to split splitting treatment to split the web at the boundary surfaces of the segments constituting the splittable conjugate fiber, thereby expressing ultrafine fibers made of one polymer and / or the other polymer.

As a method of applying an impact to a web composed of splittable conjugate fibers to develop ultrafine fibers, a method of mechanically processing the web to split the web, or applying a high-pressure liquid flow treatment to the web to apply an impact thereto And splitting the web by applying a needle punch treatment to the web to give an impact.

Examples of the method of splitting by mechanical processing include, for example, a method of splitting a web by buckling the web through a buckling machine, ie, a pair of rolls, into a push-type crimper, and buckling the web. Splitting by passing through a pair of gear rolls to bend, splitting the web by passing it between a plurality of guides and rubbing and bending, splitting the web by immersing it in a liquid and splitting it by a liquid flow Method and the like. In the case of splitting by mechanical processing, it is necessary to integrate the constituent fibers into a fabric by subjecting the web to a partial thermocompression treatment or the like.

The method of splitting by applying a high-pressure liquid flow treatment and applying an impact means splitting by a water flow (high-pressure liquid flow) obtained by injecting water from an injection hole at a high pressure. Specifically, using a device in which the injection holes having a hole diameter of 0.05 to 2.0 mm are arranged in one or more rows at an injection hole interval of 0.05 to 10 mm, the liquid is supplied from the injection holes to 20 to 200 μm.
Injection is performed at a pressure of kg / cm ² G to collide with a web placed on a support plate. The processing conditions such as the pressure of the water flow, the number of rows of the injection holes, the processing speed, and the number of times of processing may be appropriately selected according to the use of the nonwoven fabric. The support plate may have a configuration in which a high-pressure liquid flow passes through the web and the support plate, and a mesh screen or a perforated plate may be used. By appropriately selecting the structure of the mesh screen, the size of the mesh, and the like, the surface form of the nonwoven fabric can be made smooth, and a hole shape, a pattern, and the like can be provided. In addition, since the splittable conjugate fibers are split by the action of the high-pressure liquid flow, and the ultrafine fibers generated by the splitting are densely and three-dimensionally entangled and integrated, the nonwoven fabric can be formed at the same time.

In the nonwoven fabric subjected to the high-pressure liquid flow treatment,
The one obtained by using a fine mesh screen (about 100 mesh) as a mesh screen is a finely entangled ultrafine fiber of 0.4 denier or less, so that the surface is smooth and both the bulk density and the air permeability are high. Low and high filter performance can be obtained. In such a nonwoven fabric, the air permeability is preferably 40 cm ³ / cm ² · sec or less, and more preferably 30 cm ³ / cm ² · sec or less.

[0026]

Next, the present invention will be described specifically with reference to examples. The measuring method is as follows. (1) Melt viscosity (dPa · s) Using a flow tester CFT-500 manufactured by Shimadzu Corporation, the melt viscosity was measured at a melt temperature of 280 ° C. and a preheat time of 180 seconds while varying the weight of the load, and the shear rate was measured. 10
The value at 00 sec ^-1 was measured as the melt viscosity.

(2) Single yarn fineness (denier) Measured according to the method of JIS L-1015.

(3) Fineness of segment (denier) The fineness of a single yarn is measured according to the method of JIS L-1015.
The fineness after division was calculated from the number of segments and the density and ratio of the fiber-forming resin constituting the fiber.

(4) Fiber radius (r) and minimum thickness of polymer (d) The cross section of the splittable conjugate fiber is observed with an electron microscope, and r and d
Was measured.

(5) Exposure rate of polymer (%) The cross section of the splittable conjugate fiber is observed with an electron microscope, and the total circumferential length (L) in the fiber cross section and the portion where the polymer is exposed on the fiber surface are shown. Was determined by the following equation. Exposure rate (%) = (LA / L) × 100

(6) Splitting Ratio (%) The cross section of the splittable conjugate fiber was observed with an electron microscope, calculated by the following equation, and the average value of 100 fibers was obtained. When the division ratio is 80
% Or more was regarded as a pass. Division ratio (%) = (a / b) × 100 a: Number of fibers divided by about 90% or more of the number of segments b: Number of fibers before division

(7) Card Passability When the splittable conjugate fiber is put on a card machine to form a web,
Judgment as card passing was made based on the occurrence of neps and cotton loss. In addition, "O" was regarded as a pass. ：: No nep or cotton loss occurred, good card passability ×: Nep or cotton loss occurred, poor card permeability

(8) Softness (g) of nonwoven fabric Sample width 10 cm and sample length 10c according to JIS L-1096
Three sample pieces of m were prepared, and a feeling meter (MODEL FM-2) manufactured by DAIEI KEIKI was used. 15m
Place a sample piece on a slit with a width of m and measure the maximum force required when the arm pushes the sample between the slits, at the front and back of the sample, in four directions in the vertical and horizontal directions, and calculate the total value. Was. The average value of three sample pieces was expressed as the softness of the nonwoven fabric. In addition, if the softness was less than 60 g, it was judged as acceptable.
(9) Texture of non-woven fabric 10 panelists evaluate the touch and 10
The points were scored as a perfect score, and the total score was evaluated. In addition,
In the total score evaluation, a score of 60 or more (A and B) was regarded as a pass. 10 point evaluation 10-8 points: Very soft and soft. 6-7 points: Soft and soft. 4 to 6 points: somewhat hard. Less than 3 points: Hard. Total score evaluation ◎: 80 points or more ○: 60-79 points △: 40-59 points ×: 39 points or less

(10) Air permeability of the nonwoven fabric (cm ³ / cm ² ·
sec) The measurement was performed according to the method of JIS L-1096 using an air permeability measurement device KESF-8 manufactured by Kato Tech.

Example 1 A polymer having a melt viscosity of 180 was used as a constituent polymer of the splittable conjugate fiber.
0 dPa · s polyethylene terephthalate (polymer A) and melt viscosity 1250 dPa · s polypropylene (polymer B) were used. Using a composite spinneret having a fiber cross-sectional shape as shown in FIG. 1 and having 20 segments, melt-spinning was performed at a melt volume ratio of polypropylene and polyethylene terephthalate of 50:50, and the single yarn fineness was 3 Denier (the fineness after division is 0.19 denier for polypropylene and 0.11 denier for polyethylene terephthalate), the fiber length is 51 mm, and the d / r ratio is 0.1.
02. A splittable conjugate fiber in which polyethylene terephthalate completely covered the fiber surface (exposure rate: 100%) was obtained.

The obtained splittable conjugate fiber was opened in a carding process to form a web having a basis weight of 80 g / m ² . At this time,
There was no occurrence of neps or cotton loss, and the card passing property was good.

This web was placed on a net conveyor consisting of a 100-mesh mesh screen, and injection nozzles having a plurality of injection nozzles having a hole diameter of 0.12 mm and a hole interval of 1.0 mm were provided in three stages. ^2, the middle 40 kg / cm ^2, subjected to spunlace treatment on both sides of the web in the pressure of the subsequent stage 100 kg / cm ^2, subjected to splitting and entangling the web constituent fibers, woven fabric was obtained. The distance between the injection nozzle and the net conveyor was 50 mm, and the speed of the net conveyor was 100 m / min. Table 1 shows the evaluation results of the obtained nonwoven fabric.

Example 2 A splittable conjugate fiber and a nonwoven fabric were obtained in the same manner as in Example 1 except that the polymer B was changed to nylon 6 having a melt viscosity of 1700 dPa · S. Table 1 shows the evaluation results of the obtained nonwoven fabric.

[0039]

[Table 1] In the table, PP indicates polypropylene, PET indicates polyethylene terephthalate, and N6 indicates nylon 6.

In Examples 1 and 2, fibers having a small fineness after splitting were obtained, and the nonwoven fabric obtained from the fibers had low air permeability, good touch, good softness and excellent texture. Also, in the carding process in the production of the nonwoven fabric, the fibers were not substantially peeled off and split, and the card passing property was good without generating neps or fluff.

Examples 3 and 4, Comparative Example 1 The same procedures as in Example 1 were carried out except that the number of segments, the d / r ratio, and the polyethylene terephthalate (polymer A) exposure rate of the splittable conjugate fiber were changed as shown in Table 2. Similarly, a splittable conjugate fiber and a nonwoven fabric were obtained. Table 2 shows the evaluation results of the obtained nonwoven fabric.

[0042]

[Table 2] In Examples 3 and 4, fibers having a small fineness after splitting were obtained, and the nonwoven fabric obtained from these fibers had low air permeability, good touch, softness, and excellent texture. Also, in the carding step in the production of the nonwoven fabric, the fibers were not substantially separated and split, and no nep or fluff was generated.

On the other hand, in Comparative Example 1, since the number of segments of the splittable conjugate fiber was small, the fineness after splitting was large, and the nonwoven fabric obtained from this fiber had high air permeability, poor softness and texture, and Was not what was intended.

Example 5, Comparative Example 2 A splittable conjugate fiber and a nonwoven fabric were obtained in the same manner as in Example 1, except that the d / r ratio in the splittable conjugate fiber was changed as shown in Table 3. Table 3 shows the evaluation results of the obtained nonwoven fabric.
Shown in

[0045]

[Table 3] In Example 5, the card passing property was good, and the obtained nonwoven fabric had low air permeability, good touch, softness and excellent texture.

On the other hand, in Comparative Example 2, since the d / r ratio was large, the division was not easily performed in the division splitting step by the high-pressure liquid flow treatment, so that the division ratio was low, and the obtained nonwoven fabric had a fineness. It was made of a large material, and was particularly poor in softness and texture.

Example 6, Comparative Example 3 A splittable conjugate fiber and a splittable conjugate fiber were prepared in the same manner as in Example 1 except that the exposure rate of polyethylene terephthalate (polymer A) was changed as shown in Table 4. A non-woven fabric was obtained. Table 4 shows the evaluation results of the obtained nonwoven fabric.

[0048]

[Table 4] In Example 6, the card passability was good, and the obtained nonwoven fabric had low air permeability, good touch, and soft texture.

On the other hand, the nonwoven fabric obtained in Comparative Example 3 was excellent in softness and texture, but because of the large exposure rate of the polypropylene in the conjugate fiber, peeling and splitting into splittable conjugate fiber in the carding process. This was inferior in card passing properties such as occurrence of neps and cotton loss.

[0050]

As described above, in the cross-section of a splittable conjugate fiber comprising two types of fiber-forming polymers which are incompatible with each other, the rate of exposure of one of the polymers to the fiber surface is restricted, whereby the conjugate fiber is formed. At the time of preparation and at the web forming stage, the splittable conjugate fiber splits without generating neps or fluff,
For the first time, in the split splitting step, splitting is easily performed, and a splittable conjugate fiber having excellent flexibility and texture and capable of obtaining a nonwoven fabric having high wiping performance can be obtained. Furthermore, the nonwoven fabric made of the splittable conjugate fiber has excellent flexibility, hand feeling, and wiping performance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a splittable conjugate fiber, showing an example in which the total number of segments is 20.

[Description of Signs] A One polymer B The other polymer d Minimum thickness of polymer (A) r Fiber radius

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 4L041 AA07 BA02 BA04 BA05 BA12 BA23 BA24 BA49 BD07 BD11 BD20 CA06 CA21 CA38 DD01 DD06 DD14 EE01 EE06 EE14 EE20 4L047 AA14 AA21 AA23 AA27 AB02 AB08 BA04 BD01 CB01 CB10 CC03 CC

Claims (5)

[Claims] 1. A splittable conjugate fiber comprising two types of fiber-forming polymers (A) and (B) which are incompatible with each other, wherein the exposure rate of the polymer (A) to the fiber surface is 85. %that's all,
In a fiber cross section, a splittable conjugate fiber characterized in that both polymers are radially alternately arranged in a total of eight or more segments. 2. The exposure rate of the polymer (A) to the fiber surface is 1
00%, and the ratio (d / r) of the minimum thickness (d) of the polymer (A) to the fiber radius (r) in the fiber cross section is 0.1%.
The splittable conjugate fiber according to claim 1, wherein the ratio is 1 or less. 3. The splittable conjugate fiber according to claim 1, wherein the fineness of each segment is 0.4 denier or less. 4. A nonwoven fabric comprising ultrafine fibers comprising a polymer (A) and / or a polymer (B) developed by dividing the splittable conjugate fiber according to claim 1. 5. The constituent fibers are three-dimensionally entangled and integrated, and the fineness of the ultrafine fibers is 0.4 denier or less and the air permeability is 4 deniers.
5. The nonwoven fabric according to claim 4, wherein the nonwoven fabric is at most 0 cm ³ / cm ² · sec.