JPH02169720A - Thermal splitting type conjugate fiber and nonwoven fabric thereof - Google Patents

Abstract

PURPOSE:To obtain the subject conjugate fiber capable of splitting a high- melting component by heat treatment and providing nonwoven fabrics having soft hand by arranging a polyolefin component and incompatible fiber-forming polymer component in a specific state. CONSTITUTION:A thermal splitting type conjugate fiber, obtained by regulating the melting point difference between a polyolefin component (A) and a fiber- forming polymer component (B) (polyester, nylon, etc.) incompatible with the component (A) to >=20 deg.C and arranging both components in a state of both components partially exposed to the fiber surface and the high-melting component in a state of split into plural parts and capable of splitting the high-melting component. The fiber is formed into an ultrafine shape by dividing and splitting the high-melting component. If the fiber is used in nonwoven fabrics, the polyolefin component is uniformly bonded between interstices of the ultrafine fibers in the form of dots.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a composite fiber with an extremely soft texture and a nonwoven fabric thereof. More details.

The present invention relates to a composite fiber composed of a polyolefin component and a fiber-forming polymer component incompatible with the polyolefin component, and to a nonwoven fabric thereof, for producing a nonwoven fabric with very good surface feel and excellent drapability.

(Prior art) It has been proposed to use ultrafine fibers with as small a single filament fineness as possible in order to produce nonwoven fabrics with a soft texture. Koma: A satisfactory nonwoven fabric has not been obtained. To solve this problem, many methods have been proposed to date to obtain ultrafine fibers using composite fiber technology. For example,
As disclosed in Japanese Patent Publication No. 6297 and Japanese Patent Publication No. 45-9907, a method in which a nonwoven fabric is formed using a multifilamentary sheath core yarn, and then the sheath component is dissolved to turn the MIL fibers constituting the nonwoven fabric into ultrafine fibers, or As disclosed in Japanese Patent Publication No. 53-10169, a method is known in which a hollow annular composite fiber is divided by mechanical means after forming a nonwoven fabric or a woven or knitted fabric.

(Problems to be Solved by the Invention) However, when composite fibers are obtained by these conventionally known methods and used to create an ultrafine fiber nonwoven fabric, there are the following drawbacks.

In other words, the method of dissolving and removing the sheath component requires the use of a solvent, which increases the cost of the solvent and the cost of the polymer component to be dissolved, and also requires the installation of equipment for the dissolution process and the process for recovering the solvent. It has disadvantages such as having to be used.

Furthermore, when bonding the fibers of the nonwoven web, an acrylic or PVC binder is required. This also applies to the technology disclosed in Japanese Patent Publication No. 53-10169, and when making a nonwoven fabric,
After all, the above-mentioned acrylic or PVC binder is required. For this reason, the obtained nonwoven fabric was unable to exhibit its properties despite the use of ultrafine fibers, such as poor flexibility and hard feel due to the addition of a binder.

(Means for Solving the Problems) The present inventors have conducted intensive research to solve the above-mentioned problems, and as a result, they have arrived at the present invention.

That is, in the present invention, in a composite fiber consisting of a polyolefin component A and a fiber-forming polymer component B in which the polyolefin component A is incompatible, the melting point difference between the A component and the B component is 2.
0°C or higher, and has a cross-sectional shape in which the high melting point component is divided into two or more parts, and a part of the image component of the composite fiber is exposed on the fiber surface, and the high melting point component is removed by heat treatment. The gist of this invention is a thermally splittable conjugate fiber that can be split and a nonwoven fabric thereof.

FIG. 1 shows an example of a cross section of a thermally splittable composite fiber of the present invention, in which the A component is a polyolefin such as polyethylene or polypropylene, and the B component is a polyester or nylon that is incompatible with the polyolefin component. etc. The polyolefin as component A used in the present invention is as follows.

Low density polyethylene (LDPB), linear low density polyethylene (LLDPB), high density polyethylene (HDPB)
Examples include polypropylene, modified polyethylene obtained by copolymerizing ethylene or propylene with an unsaturated carboxylic acid such as acrylic acid, and modified polypropylene. The polyester of component B is mainly composed of polyethylene terephthalate and polybutylene terephthalate.
Any of polyesters copolymerized with carboxylic acids such as isophthalic acid and adipic acid as the acid component and neopentyl glycol as the glycol component can be used. Also,
As the nylon, any of nylon 6, nylon 66, nylon 12, etc. and copolymers thereof can be used. In addition, both the A component and the B component may be either a single substance or a mixture of two or more of the above compounds, as long as they are incompatible among the image components.

Next, the composition ratio of the polyolefin component A and the fiber-forming polymer component B that is incompatible with the polyolefin component A is preferably A component/B component = 10 to 70%/90 to 30% by weight, and more preferably. is 30-60%/70-4
0% is desirable. If the amount of component A is less than 10%, the adhesiveness when made into a nonwoven fabric will be poor and the strength of the nonwoven fabric will be low. on the other hand,
If it exceeds 70%, the adhesive strength will be high and the strength of the nonwoven fabric will be improved, but the adhesive area will also increase and the texture will become hard, which is not preferable.

Next, it is necessary that the difference in melting point between component A and component B is 20° C. or more. In the present invention, the fibers are divided and made into a non-woven fabric through heat treatment.

If the melting point difference between the high melting point component and the low melting point component is less than 20°C, the heat deformation temperature ranges of one stroke component will overlap, and the high melting point component will be deformed or even melted, resulting in the strength of the resulting nonwoven fabric being reduced. There are problems such as loss of texture. Therefore, in order to obtain a good nonwoven fabric.

It is necessary that the difference in melting point of the image components be 20° C. or more.

In addition, in the case of so-called sea-island fibers in which either component A or component B surrounds the other, by heat treatment.

It may take a long time to divide the fibers, or in extreme cases it may not be possible to divide the fibers into one piece, and therefore the desired soft nonwoven fabric may not be obtained. It is necessary that the

Next, in order to manufacture a nonwoven fabric using the composite fibers described above, a nonwoven web is first created by carding, and then the fibers of the nonwoven web are entangled with each other by needle punching, water needling, or the like. Next, it is made into a non-woven fabric by heat treatment, but for fibers with large heat shrinkage9, for example, in the case of bonded composite heat-splitable fibers, it is also possible to heat-treat the fibers as they are without going through the entanglement process to make them into a non-woven fabric. be.

The heat treatment can be performed by passing through a hot air dryer or a hot roll such as an embossing roll or a calender roll to form a non-woven fabric. Moreover, instead of using 100% of these fibers, other adhesive fibers or adhesives may be used in combination as necessary, and the optimum combination for the nonwoven fabric to be obtained may be selected. The heat treatment temperature can be lower than the melting point of the high melting point polymer and higher than the melting point of the low melting point polymer. The present invention will be described below with reference to nine drawings, but it goes without saying that the present invention is not limited to what is shown in these drawings.

FIG. 2 is a longitudinal sectional view of a composite spinneret device according to the present invention;
Figures 3 and 4 are lines C-C' and D in Figure 2, respectively.
-D' line cut sectional view is shown.

In Figures 2 to 4, A is spinning solution A and B is spinning solution B.
, (1) is a lower metal plate, which has a composite flow irregularly shaped discharge hole (3) at the tip of the guide hole (2). (4) is an upper metal plate, which is equipped with a capillary (5) having a discharge hole for spinning solution A, and a capillary! J-(5) is inserted substantially tightly into the inner wall of the discharge guide hole for composite flow in the lower metal plate (1).

Capilla! As shown in FIG. 3, a notch (6) serving as a passage for supplying the spinning solution B is provided on the outer circumferential portion of J-(5). Spinning solution A is Cabila! The spinning solution B is introduced from the upper end of J-(5) through the guide hole (7) of the upper metal plate (4).
and a gap (8) communicating therewith. The spinning solution B is uniformly distributed to each spinning hole by the guide hole (7), passes through the gap (8), and is equalized in pressure at the upper part of the discharge guide hole.

Furthermore, it is supplied quantitatively and uniformly through the notch (6) of the cab IJ-(5). In Figure 5, A is component A
B+ to B4 are component parts consisting of component B. By using a spinneret having a structure as shown in FIGS. 2 to 4, an undrawn cross-shaped composite fiber yarn having a configuration as shown in FIG. 5 can be obtained. After drawing the obtained undrawn yarn, when the composite fiber is made into a nonwoven fabric, it is produced through the steps shown below.

・Manufacturing process for nonwoven fabric made of heat splittable composite fibers Composite cotton → Card → Nonwoven web → Needling → Heat treatment → Product The obtained nonwoven fabric is made of heat splittable composite fibers.
It has an extremely good texture, with most of it peeling off during the heat treatment process and some of it partially adhering.

- The thermally splittable composite fiber of the second invention can be used not only for the short fiber nonwoven fabric but also for the long fiber nonwoven fabric. As an example of manufacturing a long fiber nonwoven fabric, for example, it is manufactured by the steps shown below.

・Manufacturing process for long-fiber nonwoven fabric made of thermally splittable composite fibers Composite fiber → Spreading device → Web → Embossing roll → Heat treatment → Product (effect) When using the composite fiber of the present invention, the single fiber fineness is 2 before splitting.
It has a single yarn fineness of about 8 deniers, which is comparable to that of ordinary fibers for nonwoven fabrics, and an excellent nonwoven web can be obtained. However,
Since the A component and the B component are incompatible, first, separation occurs at a part of the interface.

Furthermore, when heat treatment is performed at a temperature higher than the melting point of component A.

Component A also has a large thermal contraction, so it not only melts.

The heat shrinkage also allows for smooth division of composite fibers. Next, after the A component has been heat-treated and split into microfibers, the B component is partially bonded.

Therefore, adhesion is only partial adhesion, and the texture is also good.

(Example) Next, one embodiment of the present invention will be specifically explained using an example. In addition, the evaluation method of the product performed in the example is as follows.

(1) Non-woven fabric tensile strength, width 25m according to JIS L-1096 strip method
m.

The maximum tensile strength was measured using a test piece with a length of 100 mm.

(2) Create a test piece with a compression bending strength of 50+nm x 100mm, make this test piece into a cylindrical shape with a height of 50mm and a circumference of 10Q a+m, place it on a flat plate type load cell, and conduct a cylindrical test at a speed of 50++ un/min. The piece was compressed and the maximum load at that time was measured.

(3) Weight Measured according to JIS P-8142.

Examples 1-3. Comparative Example 1 Polyethylene terephthalate (melting point 260°C) with a relative viscosity of 1.38 (measured using an equal weight mixture of phenol and tetrachloroethane as a solvent, solution concentration 0.5g/100ml, temperature 20°C) and the first Polypropylene (hereinafter referred to as Ml) having various melt index values (hereinafter referred to as Ml) shown in the table
(melting point 170°C), the second to fourth
Using the spinneret shown in the figure (number of holes: 319), polypropylene was introduced from A and polyethylene terephthalate was introduced from B, and the discharge amounts were as shown in Table 1, respectively, at a spinning temperature of 280°C and a winding speed of 1000 m. I finished it in / minute.

The cross-sectional shape of the obtained unstretched system was as shown in FIG. The obtained yarn is gathered into a 100,000 denier tow,
The fibers were drawn at a drawing temperature of 75 DEG C. and at the draw ratio shown in Table 1, crimped using a push-in crimper, and then cut into a length of 51 mm to obtain a thermally splittable composite fiber having a fineness of 2 denier. Next, this composite fiber fabric was fed to a carding machine, and the basis weight was 80g.
/m” was obtained.Then, the nonwoven web was passed through a needle locker room with barbed needles to obtain a needle density of 160/m”.
Needling was performed with ctl. Subsequently, the web after needle punching was dried in a suction dryer for 19 minutes.
A nonwoven fabric was obtained by heat treatment at 0°C for 1 minute. As shown in Table 8, the obtained nonwoven fabric had a soft texture and a good feel. Further, for the purpose of comparison with the present invention, a composite fiber having a cross-sectional shape shown in FIG. 6(A) was manufactured as Comparative Example 1. Except for the weight ratio of component A and component B shown in Table 1, other conditions are shown in Table 1 (Continued). Using the polyethylene terephthalate used in Example 1, When short fibers of 51 mm in diameter were obtained and then passed through a card machine, card sinking occurred.
A uniform nonwoven web was not obtained.

Examples 4-5 Component A of Example 1 was replaced with high-density polyethylene (melting point 130°C
), and other conditions other than those shown in Table 2 are as follows:
A nonwoven fabric was created under exactly the same conditions as in Example 1. Table 2 shows the performance of the obtained nonwoven fabric.

From the table, it is clear that the texture is soft and the strength is excellent.

A nonwoven fabric was produced in accordance with Example 1. As is clear from Table 1, the strength of the nonwoven fabric was low, and no splitting of the composite fibers constituting the nonwoven fabric was observed.

Comparative Example 2 Table 2 (Continued) Example 6 The A component of Example 1 was polypropylene (melt index value 50 g/10 min), and the B component was Unitika's nylon 6 resin (melting point 217°C) (product name 1030BRF).
), using the spinneret shown in FIG. 2 (319 holes), spinning at a spinning temperature of 270° C. and at a winding speed of 10 QOm/min.

The obtained yarn was bundled into a 100,000 denier tow and heated at 75°C.
Stretched at a stretching ratio of 2.6, and then stretched using a push-in crimper.
After applying crimps, the fiber was cut into a length of 51 m to obtain a thermally splittable composite fiber having a fineness of 2 denier. Next, this composite fiber fabric was passed through a carding machine to form a nonwoven web with a basis weight of 8 h/m2, and then passed through a needle locker room with barbed needles for needling at a needle density of 160/am2. Ta. The nonwoven web was heat-treated at 190° C. for 1 minute using a suction dryer to obtain a nonwoven fabric.

The strength of the obtained nonwoven fabric is 3210 g, and the compression stiffness is 50 g.
It had a very soft texture.

Example 7 A nonwoven fabric was produced in the same manner as in Example 1 except that component B in Example 1 was changed to polybutylene terephthalate having a relative viscosity of 1.60. The strength of the obtained nonwoven fabric is 3550
g, compression bending strength was 56 g, strength was 9, and the texture was satisfactory.

Example 8 Component B of Example 1 was added to 5 sodium isophthalate 2.5 m
o Except for changing to 1% copolymerized polyester.

Otherwise, a nonwoven fabric was produced in accordance with Example 1.

The strength of the obtained nonwoven fabric was 3390 g, and the compression stiffness was 63.
It had a strength of 2 g and a satisfactory texture.

Examples 9 to 11 The polyethylene terephthalate used in Example 1 was used as the B component, and the various polyolefins shown in Table 3 were used as the A component to melt spin the spinneret shown in FIGS. 2 to 4 to determine the single yarn fineness. 2 denyl, A component and B component discharge ratio is 1
: Spinning the filament of 2 and immediately drawing it with air pressure,
After the fibers were opened using a fiber opening device, they were deposited on a moving porous strip to produce a web. The area ratio of the press-contact part of the web is 15%, and the density of press-contact points is 22 pieces/c++f.
Using a heat pressure welding device consisting of an engraved roll with a dotted pattern and a flat roll, partial heat pressure welding was performed at the heat welding temperature shown in Table 3 to obtain a nonwoven sheet with a basis weight of 40 g/m''. .Furthermore, the nonwoven sheet was dried in a third dryer using a hot air dryer.
Heat treatment was performed for 1 minute at the temperature shown in the table. The resulting nonwoven sheet had a soft texture and a good feel, as shown in Table 3.

Table 3 Table 3 (continued) However, PP has a density of 0.90g/ca! , MI 50
g/10 minutes, polypropylene with a melting point of 170°C was
E is density 0.96g/cIIl, M I 2h/10
Minutes, high-density polyethylene with a melting point of 130°C is
means linear low-density polyethylene with a density of 0.92 g/cut, M I of 25 g/10 min, and a melting point of 128°C.

(Effects of the invention) The thermally splittable composite fiber of the present invention becomes ultrafine fibers by splitting into one piece, and when this is used in a nonwoven fabric, the polyolefin component is uniformly dot-bonded between the ultrafine fibers. It is economical and provides a good texture without adding a new binder.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the cross-sectional shape of the fiber of the present invention. FIG. 2 is a cross-sectional view of a spinneret device for composite fibers according to the present invention, and FIGS. 3 and 4 are cross-sectional views taken along lines CC and D-D in FIG. 1, respectively. Figure 5 is
An explanatory diagram showing the cross-sectional shape of the composite fiber obtained in the spinneret device of FIG. 1. FIG. 6 is an explanatory diagram showing a fiber cross-sectional shape of a comparative example. A Spinning solution AB ■ Lower cap plate 2 3 Irregular discharge hole 4 5 Capillary 6 7 Guide hole 8 Spinning solution B Guide hole upper cap plate notch gap

Claims (2)

[Claims] (1) Polyolefin component A and polyolefin component A are incompatible fiber-forming polymer component B in a conjugate fiber that has a melting point difference of 20°C or more and two high melting point components. A thermally splittable conjugate fiber having a cross-sectional shape divided into parts as described above, in which both components of the conjugate fiber are partially exposed on the fiber surface, and the high melting point component can be split by heat treatment. (2) Polyolefin component A and polyolefin component A are nonwoven fabrics made of composite fibers composed of incompatible fiber-forming polymer component B, and the difference in melting point between component A and component B constituting the composite fibers. is 20°C or higher, and has a cross-sectional shape in which the high melting point component is divided into two or more parts, and both components of the composite fiber are partly exposed on the fiber surface, and the melting point of the low melting point component is higher than the melting point of the low melting point component. A nonwoven fabric made of thermally splittable composite fibers that are substantially split by heat treatment at a temperature of .