JPS61132625A - Conjugated fiber of high conductivity - Google Patents

Abstract

PURPOSE:The title conjugated fiber that is composed of the core layer and the sheath layer of a non-conductive polymer and the intermediate layer which is eccentrically arranged to the sheath layer and is composed of a conductive polymer containing carbon black where the core has a specific cross section area, the sheath layer has a specific thickness at the thinnest part, thus preventing the conductive substance from falling off the showing good fiber-forming properties. CONSTITUTION:A nonconductive thermoplastic polymer A and a conductive polymer B containing 15-50wt% of conductive carbon black are separately melted and the nonconductive polymer A is introduced from outer inlets 11, 12 one the pate 1 and the conductive polymer B is introduced from the inside inlet 13 on the plate 1. B runs through intermediate plate along the path 23 to double-layered conjugate nozzle 21 to form a sheath-core conjugate stream surrounding the outer surface of the nonconductive polymer A with the conductive polymer B. Then, the conjugate flow flows into the nozzle 31 of triple-layer structure on the lower plate 3 where the polymer flow is surrounded with the nonconductive polymer A from the path 32 ununiformly. Thus, the intermediate layer B is arranged between the core layer A1 and the sheath layer A2 of a nonconductive polymer where the cross section of the core layer is more than 5% and the intermediate layer is eccentrically arranged and the thinnest part of the sheath layer is less than 5/100 of the diameter of the fiber cross section.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to highly conductive composite fibers that are effective for applications that require high conductivity, such as carpets for computer rooms, and in particular, to The present invention also relates to highly conductive composite fibers that are excellent in spinnability and durability.

[Prior Art] Composite fibers containing a layer made of a conductive thermoplastic synthetic polymer containing conductive carbon black (hereinafter referred to as the S11 layer) have antistatic properties for textile products such as carpets and dustproof clothing. It has been widely used as a material that provides Typical composite forms include a double core-sheath type with a conductive layer as the core (Japanese Patent Publication No. 52-31450), and a triple core-sheath type with a conductive layer as an intermediate layer (Japanese Patent Laid-Open No. 55-1337). etc.), Guide 1! A partially surrounding bonding type in which a conductive layer and a non-conductive layer are bonded so as to partially surround the periphery of the layer (Japanese Patent Publication No. 53-44579, etc.), or a plurality of conductive layers near the fiber surface. There is a symmetrically arranged multi-core distribution type (Japanese Unexamined Patent Publication No. 132119/1983).

The double core-sheath type and triple core-sheath type composite fibers mentioned above are
Since the fi-conducting layer is not exposed on the fiber surface, the spinning property is good, and there is no problem of fibrillation due to delamination at the composite interface, so it is useful as a conductive material for mixed use in textile products. Widely used for carpets, etc.

However, in order to prevent computers from malfunctioning due to static electricity, the carpet placed between the computer has a much higher level of conductivity than a single carpet (specifically, the specific resistance value at an applied voltage of 100μ is 1×104 Such high conductive performance is difficult to obtain with conventional double core-sheath type or triple core-sheath type composite fibers, which have non-conductive sheaths of considerable thickness.

Therefore, for applications that require high conductivity, composite AT fibers with the conductive layer exposed on the fiber surface, post-processed conductive fibers coated with a conductive substance such as copper salt on the fiber surface, or Metal fibers are used.

However, in the above-mentioned partially enclosing bonded composite fiber, the conductive layer is unevenly distributed on one side of the fiber cross section, which tends to cause yarn flattening and fibrillation during spinning. In order to bond the components, the melt viscosity during spinning must be strictly controlled, so spinning is not easy and troubles are likely to occur. In addition, in the multicore distribution type composite fiber, it is not easy in industrial production to divide the plurality of conductive N layers evenly and arrange them at a position 1 to 5 μm from the fiber surface, so it is difficult to separate the conductive layer and the conductive current collecting layer. There is a problem that the composite variation is large and the yarn spinning stability is also poor.

As described above, the conventional conductive MM type composite fibers have problems in spinning or yarn quality, and are not satisfactory in any industrial production.

On the other hand, post-processed conductive fibers are complicated to produce because they require a process of coating with a conductive resin, and furthermore, there is a problem in that the coated conductive material is likely to fall off. Furthermore, metal fibers have a problem in that am fibrils during use, and these fibers are also unsatisfactory from a practical standpoint.

[Problem to be Solved by the Invention 1] The present invention does not have the above-mentioned problems of conventional highly conductive fibers, has good spinning properties, and has no problems with yarn quality such as deterioration of conductive performance and fibrillation due to shedding of IN substances. The main object of the present invention is to provide a highly conductive conjugate fiber that has excellent conductivity and is free from such problems.

Furthermore, the present invention provides highly conductive composite fibers that can be easily composited during spinning and have a good composite form.

[Means for Solving Problem L] To achieve this object, the present invention provides a conductive material comprising a core layer and a sheath layer made of a thermoplastic synthetic polymer, and a conductive carbon black containing 15 to 50% by weight of conductive carbon black. A core-sheath type composite fiber comprising a thermoplastic synthetic polymer and an intermediate layer disposed between the core layer and the sheath layer, wherein the core layer is made of am
occupies a cross-sectional area of 5% or more of the area of part m, the middle 11 layer is arranged eccentrically with respect to the sheath layer, and the thickness of the thickest part of the sheath layer is 5/100 or less of the fiber cross-sectional diameter It is made of highly conductive composite fibers characterized by:

The thermoplastic synthetic polymer (hereinafter referred to as non-conductive polymer A) forming the core layer A1 and sheath layer A2 of the highly conductive composite fiber according to the present invention is a melt-spun synthetic polymer with high fiber-forming ability. For example, polyamide, polyester, polyolefin, etc. are used, among which nylon 6,
Preferred are polyamides such as nylon 66, and polyesters such as polyethylene terephthalate and polybutylene terephthalate. In this non-conductive polymer A, antistatic improvers such as polyalkylene glycol, polyalkylene ether glycol, polyether polyamide, N-alkyl polyamide and derivatives thereof may be blended. Fiber additives may also be blended. In order to suppress the black color of the intermediate layer, it is effective to incorporate a matting agent such as titanium oxide into the non-conductive polymer A, particularly into the sheath layer A2.

On the other hand, as the thermoplastic synthetic polymer (base polymer) forming the intermediate layer B1, the same polymer as exemplified as the non-conductive polymer A is used. In order to improve the mutual adhesion of the core layer A1, intermediate layer B1, and sheath layer A2, it is preferable to use a polymer of the same type as the non-conductive polymer A as the base polymer of the intermediate layer B1.

Any known conductive carbon black may be used as the conductive carbon black to be uniformly dispersed U in the intermediate layer B1, and the amount thereof needs to be 15 to 50% by weight of the base polymer constituting the intermediate layer. . If the blending amount is too small, the conductive performance will be insufficient, and if the blending amount is too large, the silk-spinning properties will be reduced.

[Function] FIG. 13 (cross-sectional view of the fiber) showing an embodiment of the highly conductive composite fiber according to the present invention, and FIG. The explanation will be given below with reference to FIG. 3 (a partial vertical cross-sectional view schematically showing a state in which the spinneret is assembled into a spinning bag and spun) and FIG. 3 (a top view of the lower die plate of this spinneret).

The composite spinneret of the embodiment shown in FIG. 2.3 includes an upper spinneret plate 1,
It is composed of three cap plates: a middle cap plate 2 and a bottom cap plate 3.

Non-conductive polymer A and conductive polymer B are each separately melted and filtered before flowing into the polymer reservoir on the spinneret.

The non-conductive polymer A then flows into the outer inlet holes 11.12 of the upper cap plate 1 and into the inner cap plate 2, being metered by the respective metering hole ends. A two-layer composite hole 21 is bored at a position directly below one of the outer inflow holes 11,
In addition, a downstream hole 2 is provided at a position I directly below the other outside inflow hole 12.
2 is drilled.

On the other hand, the conductive polymer B is
while being measured at the end of the measuring hole, the middle mouth metal plate 2
Then, it flows along the channel 23 of the cough mouthpiece plate 2 to the position of the two-layer composite hole 21 .

In the two-layer composite hole 21, the conductive polymer 8 surrounds the outer peripheral interface of the non-conductive polymer A to form a two-layer core-sheath composite flow, and from the metering hole end to the three-layer composite hole of the lower cap plate 3. 31. In the three-layer composite hole 31, the two-layer core-sheath composite flow passes through the outer 1111J inflow hole 12, the flow hole 22, and the flow path 32 of the lower metal plate 3, and reaches the three-layer composite hole 31 through the non-conductive polymer. The particular three-layer composite configuration of the present invention, as shown in FIG. A method of partially narrowing the slit width of the throttle part (the embodiment shown in Fig. 2.3), a method of eccentrically discharging the discharge end of the two-layer composite hole 21 with respect to the three-layer composite hole 31, or a combination of these methods. It can be formed by a suitable method or the like.

In Fig. 2.3, the non-conductive polymer B flows into the three-layer composite hole 31 while being controlled by the restricting portion 33, 33', and the slit width is narrowed in a portion of the restricting portion. (Narrow width portion 33'), the amount of non-conductive polymer B flowing in from the direction of the narrow width portion is reduced, and the thickness of the outermost layer (sheath layer) is particularly thin in this portion. In this way, a composite configuration is obtained in which the intermediate layer is eccentric and the sheath layer is partially particularly thin. The slit width of the narrow part 33' and/or the narrow part and other squeeze parts (wide part 3
By changing the ratio of 3), the thickness (d) of the thin portion of the door of the sheath layer can also be changed.

For example, set the thickness (d) of the sheath layer at the thinnest part to 5% of the fiber cross-sectional diameter.
/100 or less, the slit width (L
l), the slit f% (Ll) of the wide part is about 415 or less, and the ratio of the narrow part is 20 to 1 at the center angle θ.
It may be about 80 degrees.

Further, the boundary between the narrow part 33' and the wide part 33 may be stepped, as shown in FIG. 4(A), which is a cross-sectional view taken along the central circle IV-IV. , or may be tapered as shown in FIG. 4(0).

The three-layer composite flow formed in the 3 mm joint hole 31 as described above is spun out from the discharge end 31', cooled, lubricated, and taken off in the usual manner, and subjected to stretching, heat treatment, and treatment as necessary. It is interlaced and then spun.

In this spinning process, the sheath layer and the core layer are oriented and crystallized using a conventional method in order to obtain the necessary mechanical properties as a fiber.

In the highly conductive composite fiber according to the present invention, the cross-sectional area ratio of the core layer is 5% or more, the intermediate core is eccentric with respect to the sheath layer, and the thickness of the Ra portion of the sheath layer (d > It is characterized by having a cross-sectional area of 5/100 or less of the cross-sectional diameter.If the cross-sectional area ratio of the core layer is too small, the effect of creating a three-layer composite structure, that is, the improvement of the straw spinning property and mechanical properties, will be improved. Furthermore, even if the intermediate layer is made eccentric, if the thinnest part of the 111 layer is too large to its original size, a high degree of conductivity cannot be obtained.

The composite ratio of the non-conductive layer (= core layer + 1V layer) and the conductive layer (= intermediate layer) is preferably 98:2 to 70:30, and the ratio of the core layer to the sheath layer is 5. :95-65:3
It is preferable that it is 5.

Note that the cross-sectional shape of the intermediate layer is preferably round as shown in FIG. 1, but may be of other shapes such as an ellipse, a semicircle, or a triangle.

Examples and Comparative Examples] As the non-conductive polymer A, a nylon 6 polymer having a sulfuric acid relative viscosity of 2.63 and containing 0.4% by weight of titanium oxide was used. Nylon 6 polymer containing 35% by weight of carbon black dispersed therein was melted at 290°C and filtered, then the composite spinneret shown in Figure 2.3 (center angle θ of narrow part = 120°, L
2/L1-215) to give a composite ratio (cross-sectional area ratio) of core layer, intermediate layer, and sheath layer of -25:10:65, and after cooling and oiling, it was wound at 700 m/min. .

The obtained undrawn yarn was drawn 3.4 times on a hot plate at 170° C. to obtain a 25.7 denier, 3-filament composite fiber yarn. The thickness (d/D) of the thinnest part of the sheath layer relative to the uA fiber cross-sectional diameter of the obtained composite fiber was 4.5/100 (
Example 1).

In addition, the composite ratio of the core layer, middle layer, and sheath layer was 20:15.
: Composite fiber yarn was obtained by composite spinning and drawing under the same conditions as above except that the yarn was adjusted to 65%. The thickness (d/D) of the thinnest part of the sheath m relative to the fiber cross-sectional diameter of this composite fiber is 3/1
00 (Example 2).

On the other hand, as a comparative example, the composite form was a partially surrounding bonded type in which conductive polymer B was partially surrounded by a non-conductive layer, and the composite ratio of the S layer and the non-conductive layer was 10:90. Except for this, composite spinning and drawing were carried out in the same manner as above to obtain one partially enclosed and bonded composite fiber yarn (Comparative Example 1).

In addition, as a comparative example (), the composite form was an R8 split type in which the conductive layer was divided into four and arranged symmetrically near the fiber surface, and the composite ratio of the conductive layer and the non-conductive layer was 15285. was composite spun and drawn in the same manner as in Example 1 to obtain a multicore distributed composite fiber yarn (distance from the fiber surface to the conductive layer relative to the fiber cross-sectional diameter was 5/100) (Comparative Example 2) ).

Furthermore, as a comparative example, the composite form was a two-layer concentric core-sheath type using conductive polymer B as the core layer, and the composite ratio of the conductive layer and the non-conductive layer was 10:90. Composite spinning and drawing were performed in the same manner as in Example 1 to obtain a two-layer concentric core-sheath type composite fiber yarn (Comparative Example 3).

The specific resistance value and strength and elongation of the obtained composite fiber yarn were as shown in Table 1. Further, the spinnability and drawability when obtaining the composite fiber yarn were as shown in Table 1.

Measuring method of specific resistance value of yarn: After deoiling with carbon tetrachloride, bundle it into a 1000 denier trial bundle, cut it to a measurement length of 1Qcm, coat both ends with conductive resin, and use it as an electrode. Then, in an atmosphere of 20° C. and 65% RH, the resistance value when 100 μm of direct current was applied was measured and converted to specific resistance (Ωam>).

As is clear from the results in Table 1, the composite fiber according to the present invention (Example 1.2) is different from the conventional composite fiber (Comparative Examples 1 to 3).
) has a conductivity as high as or higher than that of
Spinning and stretching were also successful.

In addition, the obtained composite fiber thread was 1300 denier, 8
3 0 filament nylon 6 drawn yarns and 40t/m
3925 denier, 1/10 gauge, 1
A level loop carpet with 8 stitches per inch and a pile height of 10 was prepared and backed with a latex made of styrene-butadiene containing 0.2% carbon fiber.

The surface resistance and human body charge voltage of the obtained carpet were measured using the following method, and the results were as shown in Table 2.

Surface resistance of carpet: After leaving a 9Qcm square sample piece in an atmosphere of 20% RH (7) at 20°C for 24 hours, the diameter was 60111111. A metal cylinder with a weight of about 20% was placed on the sample piece at a distance of 15 cm as an electrode, and the resistance value was measured using a superinsulation method. The measurement was performed four times with the electrode placed in different directions: vertically, horizontally, and diagonally, and the average was taken as the specific resistance value.

Carpet human body voltage: A 9Qcm square sample piece left under the same conditions as above.
It was measured according to the Stroll method of Rug Test Method (Jts L 1021).

In addition, we evaluated the process passability when weaving carpets,
The results are shown in Table 2.

As is clear from the results in Table 2, the composite m according to the present invention
The carpet using Mi had high conductivity and also had good process passability during carpet ¥J weaving.

[Effects of the Invention] The highly conductive conjugate fiber according to the present invention has good spinnability, does not have yarn quality problems such as fibrillation and carbon shedding (and has high conductivity and good mechanical properties). In addition, it is easy to compose fibers during spinning, and it is possible to obtain composite fibers with highly uniform composite morphology.In other words, according to the present invention, the fibers have high electrical conductivity, Moreover, composite fibers with excellent yarn quality can be produced with good spinability, and are suitable for industrial production.

This highly conductive composite fiber is effective in applications that require high conductivity, such as computer room carpets, computer-related supplies, dust-proof clothing, explosion-proof clothing, electrically conductive clothing, and screen gauze. It is suitable for dustproof clothing because it has high conductivity and no carbon shedding inside.

[Brief explanation of drawings]

FIG. 1 is a fiber cross-sectional view showing one embodiment of the highly conductive composite fiber according to the present invention. FIG. 2 is a partial longitudinal sectional view schematically showing a state in which a composite spinneret used for spinning the yarn is assembled into a spinning bag and spinning is performed. FIG. 3 is a top view of the lower spinneret plate 3 of the composite spinneret. FIG. 4(a) is a sectional view taken along the curve rV-rV in FIG. 3, and FIG. 4(b) is a sectional view showing another aspect. [Explanation of symbols I A: Non-conductive polymer

Claims (1)

[Claims] a core layer and a sheath layer made of a thermoplastic synthetic polymer;
A core-sheath type composite fiber made of a conductive thermoplastic synthetic polymer containing 50% by weight of conductive carbon black, and comprising an intermediate layer disposed between the core layer and the sheath layer, The core layer occupies a cross-sectional area of 5% or more of the cross-sectional area of the fiber, the intermediate layer is arranged eccentrically with respect to the sheath layer, and the thickness of the thinnest part at the back of the sheath layer is 5% of the cross-sectional diameter of the fiber. /
A highly conductive composite fiber characterized by having a conductivity of 100 or less.