JPH0366404B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a white conductive composite fiber that has excellent antistatic performance and improved metal abrasion resistance. (Prior Art) Conventionally, electrostatic disturbances such as discharge shocks caused by walking on a carpet and touching a door handle, spark discharges due to frictional charging, and dust adhesion have been very troublesome and caused considerable damage. It was something that caused a sense of pleasure. One of the effective means of imparting antistatic properties to synthetic fibers and natural fibers is a conductive composite in which a conductive component made of a polymer in which conductive carbon black is dispersed and a protective component made of a fiber-forming polymer are bonded together. There is a method of mixing a small amount of fiber. However, since conductive composite fibers using carbon black are colored black or gray, their uses are actually limited. In recent years, there has been active research into conductive fibers containing white or colorless conductive substances in order to improve the black appearance. Among them, conductive metal oxides whose main components are zinc oxide and tin oxide, and fine particles with coatings of these metals, are close to white and have been found to have relatively good conductivity and kneadability, and have attracted attention. There is. However, in order to obtain conductivity comparable to that of conductive composite fibers using conductive carbon black, it is necessary to
Several issues remain to be resolved, such as the need to mix three times as many conductive metal oxide particles.
Practical implementation is delayed. Although conductive composite fibers in which a conductive component in which a large amount of particles such as conductive metal oxides are dispersed are exposed on the fiber surface exhibit excellent antistatic performance, they have the drawback of significant metal abrasion. In order to improve these drawbacks, a special composite fiber consisting of a sea-island structure part whose island components have conductivity and a single polymer part has been proposed in Japanese Patent Laid-Open No. 56-58008. However, the disadvantage is that the antistatic performance is inferior to those in which the conductive component is exposed on the surface.
Further, a conductive composition in which a large amount of particles such as a conductive metal oxide is dispersed has extremely low melt flow (melt fluidity), and it is not easy to form it into fibers. For this reason, polymers that have been copolymerized to lower the viscosity are used or plasticizers are added.
Spinability is often sacrificed. (Problems to be Solved by the Invention) With this background in mind, the present inventors have developed a white material that exhibits excellent antistatic performance equivalent to that of a fiber in which the conductive component is exposed on the surface of the fiber, and has improved metal abrasion resistance. As a result of intensive research aimed at obtaining conductive composite fibers,
The present invention has now been completed. (Means for Solving the Problems) That is, the present invention provides a conductive composition _P1 ' in which particles of a metal or a conductive metal compound are dispersed in a polyolefin P1 in an amount of 40 to 80% by weight, and a conductive composition _P1 ' that is compatible with the polyolefin _P1 . A mixture A of a fiber-forming polymer P ₂ having no fiber-forming polymer P 2 and a non-conductive fiber-forming thermoplastic polymer B are bonded, the mixture A is exposed on the fiber surface in a width of 3 μm or less, and the composition A white conductive material with no metal abrasion, characterized in that the substance _P1 ' is partially exposed through an opening in the length direction of the fiber, and the composite fiber has a metal abrasion of 15 minutes or more. This relates to composite fibers. The thermoplastic polymer P ₁ used in the present invention can be any polymer as long as it is not compatible with P ₂ described below, and includes polyamides such as nylon 6, nylon 66, and nylon 12, polyethylene terehetalate,
Polyesters such as polybutylene terephthalate, polyolefins such as polyethylene and polypropylene, polyurethanes and their copolymers,
Preferred are polyethers such as polyoxylene (polyethylene oxide) and their derivatives (eg, block copolymers of polyethylene oxide/poyethylene terehetalate), polyvinyl alcohol, polycalactone, and the like. The conductive particles used in the present invention are particles of a metal or a conductive metal compound, or particles having a film thereof on the surface, and have a specific resistance in powder form.
All kinds of particles can be used as long as they are about 10 ⁴ Ω·cm or less. Suitable conductive particles include highly white metal oxides such as tin oxide, zinc oxide, copper oxide, cuprous oxide, indium oxide, zirconium oxide, and tungsten oxide, and metals such as silver, nickel, copper, and iron; Examples include alloys of copper sulfide, copper iodide, zinc iodide, and other metal compounds. Many metal oxides are semiconductors that are close to insulators and often do not exhibit sufficient electrical conductivity for the purpose of the present invention. However, for example, by adding a small amount (50% or less, especially 25% or less) of a suitable second component (impurity) to the metal oxide, the conductivity can be strengthened and sufficient conductivity can be obtained for the purpose of the present invention. It is obtained to have . As such conductivity enhancers, antimony oxide can be used for tin oxide, and metal oxides such as aluminum, potassium, indium, germanium, tin and the like can be used for zinc oxide. Furthermore, the above metals, such as titanium oxide, zinc oxide, magnesium oxide, tin oxide, iron oxide, silicon oxide, aluminum oxide, etc.
Particles having a conductive coating of metal oxide or metal compound may also be used. The conductivity of conductive particles is determined by the specific resistance in powder form.
It is preferably about 10 ⁴ Ω·cm or less, particularly about 10 ² Ω·cm or less, and most preferably about 10 ¹ Ω·cm or less. In fact, a value of about 10 ² Ω・cm to 10 ^-2 Ω・cm can be obtained,
Although it can be suitably applied to the purpose of the present invention,
Those with even better conductivity are even more preferable. The specific resistance (volume resistivity) of the powder is determined by filling an insulating cylinder with a diameter of 1 cm with 5 gr of the sample, and using a piston from the top.
Apply a pressure of 200Kg and apply a DC voltage (e.g. 0.001~
1000V) (at a current of 1mA or less) and measure. Further, the conductive particles must have a sufficiently small particle size. Although it is not impossible to use particles with an average particle size of 1 to 2 μm, usually the average particle size is 1 μm or less,
In particular, those having a diameter of 0.5 μm or less, most preferably 0.3 μm or less are used. The conductive particles are dispersed in the thermoplastic polymer P ₁ by stirring and mixing (kneading) in a molten state, but it is preferable to make the dispersion as uniform as possible. If necessary, it is also preferable to add a small amount of a particle dispersant. The mixing ratio of conductive particles varies depending on the type, conductivity, chain-forming ability, properties and crystallinity of _P1 , etc., but is in the range of about 40 to 85% by weight, and in most cases 60 to 80% by weight. It is. 40% by weight
If it is less than that, sufficient conductivity will not be exhibited;
Even if it exceeds 85% by weight, the conductivity reaches saturation, and the melt fluidity and stringiness are significantly reduced. The fiber-forming thermoplastic polymers _P2 and B used in the present invention can be any fiber-forming polymer, including nylon 6, nylon 66, nylon 12
Suitable are polyamides such as, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polyethylene and polypropylene, polyurethanes, and copolymers thereof. In particular, nylon 6, nylon 66, polyethylene terephthalate, and polypropylene are currently the most commercially produced synthetic fibers, and are most suitable as the protective component B of conductive composite fibers that are often used in combination with these.
The combination of P ₂ and B is preferably a combination of the same or similar polymers from the viewpoint of preventing peeling due to stretching or the like. It is also possible to improve its dye receptivity by known methods (for example by copolymerizing to introduce basic or acidic dyeing sites) to facilitate blending or interdying with synthetic or natural fibers. Alternatively, matting agents, pigments, coloring agents, stabilizers, antistatic agents (polyalkylene oxides, surfactants, etc.), etc. may be added. The fiber of the present invention comprises the above conductive composition _P1 and the above conductive composition P1.
This is a composite fiber in which mixture A of P ₂ and the protective component B described above are bonded together. The fact that A occupies a part of the fiber surface is a necessary condition for the conductive composition P ₁ ' to be exposed to the fiber surface. The length of the part that A occupies on the fiber surface in the cross section of the fiber (referred to as the exposed width of A) is the upper limit of the length of the exposed part of the opening of _P1 , and from the standpoint of metal abrasion, the narrower the better, 3 μm.
The thickness is preferably at most 1 μm, particularly preferably at most 1 μm. Furthermore, in the fibers of the present invention, the conductive composition P ₁ ' must be partially exposed through openings in the length direction of the fibers, and the interval between exposed openings is 0.1 to 200 mm.
is preferred. If P ₁ ', in which a large amount of particles such as metal oxides are dispersed, is exposed at intervals of less than 0.1 mm, metal abrasion becomes significant and problems such as frequent yarn breakage occur during the stretching and twisting process. On the other hand, in order to exhibit antistatic performance equivalent to that of a fiber in which the conductive component is (continuously) exposed on the fiber surface, the interval between exposed openings is preferably 200 mm or less, particularly preferably 10 mm or less. If it exceeds 200 mm, the antistatic performance cannot be fully demonstrated, and the mixing ratio must be increased. The interval between the opening exposed portions of P ₁ ' depends on the exposed width of A above, but in the present invention, P ₁ ' and P ₂
It is controlled by the mixing ratio and melt flow rate ratio. The mixing ratio of the conductive component P ₁ ′ is
In order to partially expose P ₁ ' in the longitudinal direction of the fiber, the content is preferably 70% by weight or less, particularly preferably 40% by weight or less. On the other hand, if this mixing ratio is small, the interval between occurrences becomes long and there is a tendency that sufficient antistatic performance is not exhibited, so it is preferably 5% by weight or more, particularly preferably 10% by weight or more. The melt flow rate of P ₁ ' tends to decrease significantly because a large amount of conductive particles are dispersed. Therefore polymers for fibers as P ₂ ,
Alternatively, if the modified polymer is used, P ₂ for P ₁ ′
The melt flow rate ratio of is usually greater than 1 in combination. If this melt flow rate ratio is close to 1, the conductive component tends to be exposed on the fiber surface in openings depending on the mixing ratio or at short intervals, so it is preferably 3 or more, particularly 10 or more. In particular, when the exposed width of A is narrow as shown in Figures 2 to 4, the conductive components with a low melt flow rate gather inside the interior where the flow rate is high, and the intervals between the exposed openings are large compared to the mixing ratio. Therefore, it is suitable. The fiber of the present invention can be produced by a melt spinning method (composite), but it is necessary that the conductive component P ₁ ' is partially exposed through an opening in the fiber length direction. As mentioned above, such fibers are made of a conductive composition in which conductive particles are dispersed in a thermoplastic polymer _P1 .
Mixture A of P _1'5 to 70 parts by weight and 30 to 95 parts by weight of a fiber-forming thermoplastic polymer P ₂ which has a melt flow rate 3 times or more that of P ₁ and has no compatibility, and a non-conductive It is important to melt spin (composite) the fiber-forming polymer B. In addition, this can be achieved by making the following special efforts in designing the cap. That is, if (a) a polymer introduction hole with a shear rate of 10 ² sec ^-1 or more is provided just before A and B merge, then (b) the internal orifice for forming the exposed part of A will be 0.07 mm on the short side. (c) When the flow velocity of A immediately before merging is V _A , the flow velocity of B is V _B , and the flow velocity of the composite flow immediately after merging is V _{A + B} , these should be approximately equal, and ,V _A ＜V _B ＜V _A+B
It is preferable that In the present invention, the conductive composition is not used alone, but rather (incompatible with the conductive composition).
Since it is handled as a mixed flow with a fiber-forming polymer, it becomes possible to easily produce composite fibers with a high mixing ratio of conductive particles, which has been difficult to form into fibers in the past. The fibers of the invention must have sufficient electrical conductivity, preferably having a non-resistance of less than 10 ⁷ Ω·cm, particularly preferably less than 10 ³ Ω·cm.
Furthermore, the fibers of the present invention must have a metal abrasion resistance of 15 minutes or more according to the evaluation method described below, and preferably have significantly improved metal abrasion resistance of 20 minutes or more (Example 1, (See Comparative Examples 1 and 2). Composite ratio (cross-sectional area occupancy) of conductive composition P ₁ ′
Since conductive components containing a large amount of conductive particles tend to have poor spinnability, the content is usually preferably 30% or less, particularly preferably 15% or less. On the other hand, as the composite ratio becomes smaller, the conductivity tends to become unstable or decrease;
% or more is preferable, and 3% or more is particularly preferable. The fibers of the present invention can be produced in white or nearly colored fibers, for example, with a whiteness (reflectance) of 60% or more, and in contrast to white and pale colors, for which conventional carbon black-based conductive composite fibers were unsuitable. It can also be used in textile products. In the form of a continuous filament or staple, it can be mixed with other chargeable natural fibers or man-made fibers in an uncrimped or crimped state to impart antistatic performance to textile products. The mixing rate is usually about 0.1 to 10%, but of course, depending on the purpose, a mixing rate of 10 to 100% or 0.1% or less may be applied. Mixing includes kneading, doubling, twisting,
It can be carried out by blending, interweaving, interweaving, or any other known method. The present invention will be explained below with reference to Examples. % indicates weight % unless otherwise specified. The melt flow rate was determined according to JIS K7210 (1976), that is, the inner diameter of the die was 0.5 mm, and the load was
The temperature was 2.16 Kgf, the temperature was the spinning temperature, and the operation was performed using Method A. Conductivity was evaluated by bundling 60 single threads with a length of 10 cm and gluing both ends with metal terminals and conductive adhesive, applying a DC voltage of 1KV to measure the resistance value, and then calculating the specific resistance. . The metal abrasion resistance is a 20 denier 3-filament thread (however, one conductive filament is used, and the remaining 2
This book uses a kneaded yarn made of non-conductive filaments with no conductive components, and runs the yarn at a speed of 100 m/min on a stainless steel wire with a diameter of 35 μm (thread tension before contact is 4 to 5 g, contact angle is 45°) was evaluated based on the cutting time of stainless steel wire. The antistatic property is determined by knitting 200 denier 48 filament circular knitted fabric of nylon 6 at approximately 6 mm intervals (1 in 10).
This knitted fabric was thoroughly washed and dried, rubbed lightly with a woolen cloth 15 times on a wooden table in an atmosphere with a temperature and humidity of 25°C and 33%, and evaluated by the electrostatic voltage after 1 minute.
According to this evaluation method, it is possible to prevent electrostatic damage under most circumstances, even if the charged voltage is 2000V or less. Example 1 Titanium oxide particles having a tin oxide (SnO ₂ ) film on their surfaces are mixed with 1.5% antimony oxide and fired to make the particles conductive. The average particle size of C is 0.25μm (the variation range of particle size is 0.20~0.30μm)
m), the tin oxide content is 15%,
It had a specific resistance of 4.3 Ω·cm, an appearance of pale gray-blue close to white, and a whiteness (light reflectance) of 83%. Approximately 25% polypropylene powder with melt flow 15
and the above C75% were mixed and further melted and kneaded to obtain a conductive composition P ₁ '. As a particle dispersant, a block copolymer of polyethylene oxide/polybutylene oxide (copolymerization ratio 3/1) with a molecular weight of 4000 is added at 0.3% to C, and when mixed with polypropylene powder, it is used as a fluidity improver. 0.5% magnesium stearate salt was added to C,
The melt flow rate of P ₁ ' was 0.1. A ₁ :2 blend of P 1 ' pellets and nylon 6 pellets with a melt flow rate of 2.0, and a mixture of nylon 6 with a molecular weight of 16,000 and 0.35% titanium oxide particles added as a matting agent were prepared as shown in Figure 2. (However, one conductive filament was used, and the remaining two were hybrid yarns consisting of non-conductive filaments with no conductive component.)
The composite ratio (volume) of both components was 1:1, and the spinning temperature was
Spun at 280℃ from an orifice with a diameter of 0.25mm,
It was rolled up at a speed of 800 m/min while cooling and oiling. Then stretched at 90℃, 2.6 times, and further stretched at 170℃.
After being brought into contact with a hot plate, the yarn was wound into a pirn while being twisted at 12 T/m to obtain a drawn yarn _Y1 of 3 filaments of 20 denier. Comparative example 1 Using polypropylene with a melt flow of 50,
A conductive composition P ₁ ″ was obtained in the same manner as in Example 1. Titanium oxide particles were added to _{P 1} ″ and nylon 6 with a molecular weight of 16,000.
The yarn containing 0.35% was spun at a composite ratio (volume) of 1:10 in the same manner as in Example 1, and then stretched and twisted to form a drawn yarn.
Got _Y2 . In addition, in spinning Y ₂ , the yarn breakage rate is
The yarn breakage rate was 17%, higher than 7% in Example 1, and in the case of stretching and twisting, nearly 40% of the yarns were broken at a winding amount of about 400 g to 800 g, and all the travelers had groove cut flaws. Comparative Example 2 A core-sheath type composite structure in which a conductive component is contained in the core was spun, drawn and twisted in the same manner as in Example 1, and a drawn yarn Y ₃
I got it. Table 1 shows the performance of these drawn yarns. _Y1 ～ _Y3
Both exhibit excellent electrical conductivity with a specific resistance of about 10 ³ Ωcm, but the core-sheath type Y ₃ is significantly inferior in electrical conductivity. Furthermore, _Y2 is extremely poor in terms of metal abrasion resistance. On the other hand, it can be seen that _Y1 , the fiber of the present invention, is excellent in both antistatic performance and metal abrasion resistance. Next, each of Y ₁ to _{Y 3} was combined with 2600 denier 140 filament of nylon 6 thread and crimped, and one of the 4 courses was used, and the other 3 courses were crimped 2600 denier 140 filament of nylon 6 thread. Using tufted carpet (loop, mixing rate
0.19%). The carpets were dyed yellow with an acid line dye in a conventional manner, but the conductive fibers were not noticeable in any case, and the carpets had the same appearance as carpets that did not contain conductive fibers. Walking on the resulting carpet with the skin sheath (25℃, 20%RH)
When the voltage on the human body was measured, it was -2.0KV for the carpet mixed with the fiber _Y1 of the present invention, and _Y2
It had excellent anti-static performance equivalent to -1.9KV of carpet mixed with On the other hand, the carpet mixed with _Y3 had a voltage of -4.4KV, and I felt a discharge shock when I touched the grounded handle. In addition, carpets that use crimped yarn with _Y3 yarn for all courses are -
It was 2.5KV. For comparison, in a carpet made only of 2600 denier 140 filament of nylon 6-wound yarn, the voltage on the human body was -9.2 KV, and when the person touched the grounded handle, the discharge shock was intense and caused quite a sense of fear. It was something that gave birth to something.

[Table] (Effects of the invention) The fiber of the present invention is a white conductive composite fiber that exhibits excellent antistatic performance equivalent to that of a fiber with an exposed conductive component and has improved metal abrasion resistance. It can also be used for white or light-colored textile products, for which carbon black-based products have conventionally been unsuitable. In addition, the production method of the present invention handles the conductive component with low melt flowability not alone but as a mixed stream with the fiber-forming polymer, so it has excellent silk-spinning properties and is highly applicable to industrial production. It can be said that the industrial value is extremely large.

[Brief explanation of drawings]

2 to 4 are preferred specific examples of cross-sectional views of the fibers of the present invention, and FIG. 1 shows one embodiment.

Claims (1)

[Claims] 1 Conductive composition in which 40 to 80% by weight of metal or conductive metal compound particles are dispersed in polyolefin _P1
A mixture A of a fiber-forming thermoplastic polymer P ₂ that is incompatible with P ₁ ' and the polyolefin P ₁ , and a non-conductive fiber-forming thermoplastic polymer B are joined, and the mixture A becomes a fiber. A conjugate fiber having a width of 3 μm or less exposed on the surface and in which the composition P ₁ ' is partially exposed through openings in the fiber length direction, and the conjugate fiber has a metal abrasion resistance of 15 minutes or more. A white conductive composite fiber with no metal abrasion properties.