JPH043450B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a novel antistatic composite fiber. Specifically, the present invention relates to antistatic composite fibers that are not abrasive to metals and are industrially easy to manufacture. (Prior Art) It is well known that fibers, especially hydrophobic fibers such as polyester, polyamide, polyacrylonitrile, polyolefin, etc., generate a significant amount of static electricity due to friction, etc., and the electrostatic voltage often exceeds 10 kV, causing various problems. There is. For this reason, many proposals have been made regarding antistatic properties (imparting antistatic properties). One method is to mix metal fibers with chargeable fibers, but the antistatic properties deteriorate due to breakage due to bending during processing and use, and it is difficult to mix, inter-knit, and inter-weave with other fibers. However, it has drawbacks such as its unique metallic luster which lowers the quality of the product. In addition, fibers plated with metal or fibers coated with conductive substances have many drawbacks, such as extremely high production costs, often peeling off due to bending or friction during processing or use, and poor durability. have Furthermore, fibers with conductive particles such as carbon black or metal powder dispersed throughout the thermoplastic polymer are
When conductive particles are dispersed to such an extent that conductivity is imparted, spinnability, strength and elongation are inevitably reduced, and it is extremely difficult to obtain a product that can be put to practical use. In order to overcome these drawbacks, Japanese Patent Publication No. 52-31450 discloses fibers in which a thermoplastic polymer in which conductive particles such as carbon black or metal powder are dispersed and a fiber-forming polymer are composited side-by-side or core-sheath.
It has been proposed in Japanese Patent Publication No. 58-44579, Japanese Patent Publication No. 57-25647, etc. The cross-sectional shapes of known antistatic composite fibers are classified into one of the following types. That is, 1. side-by-side type, 2. core-sheath type, and 3. thin-skinned core-sheath type. Among these, in the side-by-side type, since the conductive component containing conductive particles is exposed on the surface of the fiber, the metal abrasion of the fiber is large, and this poses a significant inconvenience in the manufacturing and processing process of the fiber. In addition, core-sheath type composite fibers, which have a conductive component as their core, have the drawback of being difficult to cause corona discharge and having poor antistatic properties because the conductive component is wrapped in a non-conductive component. be. For this reason, there is a method of increasing the discharge performance by mixing metal particles into the sheath (Japanese Patent Application Laid-Open No. 60-224813), and a method of dissolving and removing the sheath component (Japanese Patent Application No. 1983-224813).
No. 254849) have been proposed, but industrial implementation is extremely difficult. Thin core-sheath type composite fiber (Japanese Patent Application Laid-open No. 110920/1983) is an extremely excellent method for eliminating metal abrasion and obtaining antistatic properties, but it is not sufficient to obtain sufficient antistatic properties. When the film of the conductive component is made thinner, the film is more likely to be torn, metal wear is more likely to occur, and stable production is difficult. (Problems to be Solved by the Invention) An object of the present invention is to provide a novel antistatic composite fiber that is not abrasive, has excellent antistatic properties, and can be easily manufactured industrially. It's about doing. (Means for solving the problem) The present invention consists of a non-conductive component having a specific resistance of 10 ⁷ Ω·cm or more made of a fiber-forming polymer, and a non-conductive component having a specific resistance made of a thermoplastic polymer and inorganic conductive particles.
In composite fibers with conductive components less than 10 ⁷ Ω・cm,
The cross-sectional shape of the conductive component is composed of a thick part surrounded by a non-conductive component, and a bent tail part connected to the thick part and at least a part of which reaches the periphery of the fiber, and is conductive. The component is on the fiber surface 1.5μm
The antistatic composite fiber is characterized by being intermittently exposed in the following widths. As the inorganic conductive particles used in the present invention, any type of particles can be used as long as they have a specific resistance of about 10 ⁴ Ω·cm or less in powder form. Not only metal oxides with high whiteness and particles with metal oxide coatings, but also carbon black, metal powders (such as silver, nickel, copper, iron, or alloys thereof), copper sulfide,
It is also possible to use highly colored metal compounds such as copper iodide, zinc sulfide, and cadmium sulfide. Metal oxide particles include tin oxide, zinc oxide,
Examples include particles of copper oxide, cuprous oxide, indium oxide, zirconium oxide, and tungsten oxide. 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 an appropriate second component (impurity) to the metal oxide,
The conductivity is enhanced and a conductivity sufficient for the purpose of the present invention is obtained. 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, particles in which a conductive film of the above metal oxide or metal compound is formed on the surface of non-conductive inorganic particles such as titanium oxide, zinc oxide, magnesium oxide, tin oxide, iron oxide, silicon oxide, or aluminum oxide are also 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 preferred. The specific resistance (volume resistivity) of the powder is determined by filling an insulating cylinder with a diameter of 1 cm with 5 g 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, the average particle size is usually 1 μm.
Hereinafter, those having a diameter of 0.5 μm or less, most preferably 0.3 μm or less are used. The mixing ratio of conductive particles to the conductive component varies depending on the type of particles, conductivity, particle size, chain-forming ability of particles, and the properties and crystallinity of the binder polymer to be mixed, but is usually 10 to 85%. % (by weight), and in many cases is about 20 to 80%. The thermoplastic polymer that is mixed with the inorganic conductive particles to form the conductive component is not particularly limited and can be arbitrarily selected. For example, polyamide,
Polyester, polyolefin, polyvinyl,
A number of thermoplastic polymers include polyethers. A fiber-forming polymer is preferable from the viewpoint of spinnability, but even if the spinnability is poor, if a fiber-forming polymer is used as the non-conductive component in combination, a composite fiber with good spinnability can be obtained. You can get it. Among such polymers, polymers with a degree of crystallinity of 60% or more that have poor affinity with fiber-forming non-conductive polymers are preferred, and such polymers include polyethylene, polypropylene, polyoxymethylene, polyethylene oxide, and its derivatives (e.g. polyethylene oxide/
Examples include block copolymers of PET), polyvinyl alcohol, and polycaprolactone. Among these polymers, polyethylene is particularly preferred. The specific resistance (volume resistivity) of the conductive component is 10 ⁷ Ω・
It needs to be less than cm, preferably 10 ⁴ Ω·cm or less, and preferably 10 ² Ω·cm or less. Conductive components also include dispersibility (e.g. waxes, polyalkylene oxides, various surfactants, organic electrolytes, etc.), colorants, pigments, stabilizers (antioxidants, ultraviolet absorbers, etc.), and fluidity. Improvers and other additives can be added. As the fiber-forming polymer for the composite fiber, any material that can be spun can be used. Among them, polyamides such as nylon 6, nylon 66, nylon 12, and nylon 610, polyethylene terephthalate,
Particularly suitable are polyesters such as polyethylene oxybenzoate and polybutylene terephthalate, polyacrylonitrile, and copolymers and modified products of these polymers. Additives such as matting agents, pigments, colorant stabilizers, antistatic agents (polyalkylene oxides, various surfactants, etc.) can be added to the fiber-forming polymer. Although the composite ratio (cross-sectional area occupancy) of the conductive components in the composite fiber of the present invention is arbitrary, it is usually 3 to 40%,
Particularly preferred is 4-20%, most often 5-15%. If the composite ratio is small, the antistatic property will be insufficient,
If too much, the thread quality deteriorates. The cross section (outline) of the conjugate fiber of the present invention may be circular or non-circular and is not particularly limited, but it is preferable that the circular cross-sectional area has a circular cross-section with a part of the concave portion. In the composite gun fiber of the present invention, the shape of the conductive component is important. That is, the cross-sectional shape of the composite fiber of the present invention is as follows: 1. The cross section of the conductive component is composed of a head portion and a tail portion. 2 The head is wrapped in a non-conductive component, and a portion of the tail reaches near the fiber periphery. 3 Conductive components are intermittently exposed on the fiber surface. It is something. The shape of the conductive component is shown in Figures 1, 5, and 6.
As shown in FIGS. 7 and 7, a shape resembling a tadpole or a comb, for example, is suitable, having a thick portion corresponding to the head and a band-like portion corresponding to the tail. The head can have any shape such as a circle, an ellipse, a triangle, or a square, but it is the part where most of the conductive components, for example, 60% or more, are gathered. Even when the tail can be clearly distinguished from the head (Figure 5),
It is also preferable that they cannot be distinguished (FIG. 7). The tail is a band-like part that is connected to the head and is thinner than the head; the width may be the same from the head to the vicinity of the tip, or the width may gradually become narrower, or it may become thinner or wider. , discontinuous, etc. are suitable. Although a straight tail shape is suitable, a curved shape is more preferred. As for the position of the conductive component in the cross section of the fiber, it is preferable that the head portion is wrapped in the non-conductive component and located approximately at the center of the fiber, and only the tip of the tail portion reaches near the fiber surface. In the fiber cross section, the shape of the conductive component may be the same in the length direction of the fiber, but the shape may change. In particular, the shape or width of the tail may vary gradually along the length of the fiber. This indicates that the head is continuous along the length of the fiber, but the tail may be continuous or discontinuous. As explained above, the cross-sectional shape of the composite fiber of the present invention is a novel shape that is completely unknown among known core-sheath type or side-by-side type antistatic composite fibers. In the composite fiber of the present invention, the conductive component is intermittently exposed on the fiber surface. The exposed portion is the tip of the tail or a portion near it, and the width of the exposed portion is preferably 1.5 μm or less, more preferably 1 μm or less. Although the length of the exposed portion is arbitrary, the ratio of the exposed portion is preferably 90% or less, more preferably 70% or less, and most preferably 50% or less. If the width of the exposed portion is large or the proportion of the exposed portion is large, metal wear is likely to occur. (Function) Since the conductive component has a head and a tail, and only a part of the tail reaches the vicinity of the fiber, it achieves the excellent antistatic properties that are the object of the present invention. The reason why it is possible to achieve a fiber that has good properties and is not abrasive is thought to be as follows. In other words, the specific resistance of the head is
The conductive components of less than 10 ⁷ Ω・cm are aggregated to a certain thickness or more (for example, 5 μm or more) and are continuous in the length direction of the fiber, which facilitates the movement of charge in the length direction of the fiber. It is thought that the This function is essential for antistatic composite fibers. on the other hand,
The tail is connected to the head, and part of it reaches near the fiber surface and is intermittently exposed, so it is thought that when the fiber is charged, charge removal by corona discharge occurs at a low potential. This function is also essential for antistatic composite fibers. Further, since the tail portion is band-shaped and only intermittently exposed on the fiber surface, no trouble due to abrasion occurs during fiber production and processing, and it is thought that production is easy. (Example) Example 1 Conductive particles obtained by mixing and firing 1.5% antimony oxide with titanium oxide particles having a tin oxide (SnO ₂ ) film on the surface (average particle size: 0.25 μm, content of tin oxide: 15%, specific resistance: 7Ω・cm, whiteness (light reflectance): 8.3%) 75 parts, molecular weight approximately 50000, melting point 103℃
A1 is a conductive polymer obtained by uniformly dispersing and kneading 25 parts of low-density polyethylene and 0.5 parts of magnesium stearate (flow improver). Molecular weight approx.
16000, titanium oxide on nylon 6 with a melting point of 215℃
The polymer to which 0.8% was added is designated as B1. Conductive polymer A1 and polymer B1 (mixing ratio 10
%) It was spun from an orifice with a diameter of 0.25 mm at a spinning temperature of 280°C so as to have the cross-sectional shape shown in Table 1, and was wound at a speed of 800 m/min while being cooled and oried. Next, the yarn was drawn at a draw ratio of 2.6 times using a heated roller at 80°C, and further brought into contact with a heated plate at 170°C and then wound to obtain drawn yarns Y ₁ to Y ₄ of 18 denier/filament. The conductivity (specific resistance), antistatic property, and
Table 1 shows performance such as metal abrasion resistance and the condition of the fiber side surface observed with a scanning electron microscope.

[Table] Antistatic property was evaluated by the following method. Normal 6 nylon drawn yarn (210 denier / 54 filaments) is knitted using a circular knitting machine, and the above yarns Y ₁ to Y ₄ are knitted at intervals of 1 every 10 turns to determine the mixing rate.
Create a 0.85% circular knit fabric. After removing the spinning oil by scouring, thoroughly washing with water and drying at 80℃ for 3 hours, it was further dried in an atmosphere of 25℃ and 30% RH for 6 hours.
Humidify for hours. After that, 15 minutes with cotton cloth at the same temperature and humidity.
It was rubbed twice, and the charged voltage was measured after 10 seconds. Metal abrasion resistance was measured on a stainless steel wire with a diameter of 35 μm.
Evaluation was made based on the cutting time of the stainless steel wire when the yarn was run at a speed of 100 m/min (yarn tension before contact: 4 to 5 g, contact angle: 45°). For conductivity, bundle 5 single threads of 10 cm length and connect both ends with metal terminals and conductive adhesive (Fujikura Kasei Dotite D).
-550), applied a DC voltage of 10 V to measure the resistance value, and evaluated based on the calculated specific resistance of the conductive component. Each of the yarns Y ₁ to _{Y 4} had a specific resistance on the order of 10 ³ Ω·cm and exhibited good conductivity. Antistatic property is Y ₁
~ _Y3 was good at 2.0 KV or less, but _Y4 , in which the conductive polymer was not exposed on the fiber surface, had poor antistatic properties. In addition, metal abrasion resistance is small for Y ₁ and Y ₄ ,
Y ₂ and Y ₃ showed significant metal abrasion properties. Y ₂ and Y ₃
could not be produced stably because the wear of the traveler during stretching of the yarn was extremely large. In this way, _Y1 was the only yarn with good antistatic properties and low metal abrasion. Example 2 A polymer containing polyethylene terephthalate with a molecular weight of 15,000 and 0.65% titanium oxide as a matting agent was used as the non-conductive polymer, and A1 used in Example 1 was used as the conductive polymer, and the cross-sectional shape shown in Table 2 was obtained. The fibers were composited side-by-side in the nozzle so as to have the following properties, and then covered with a thin non-conductive polymer sheath, and spun from an orifice with a diameter of 0.3 mm at a spinning temperature of 282°C. After cooling and oiling,
The yarn was wound at a speed of 10 min, then stretched 3.1 times using a heated roll at 85°C, and wound while being heat-set using a plate heater at 150°C to obtain a 25 denier/6 filament yarn. The cross-sectional shapes and performances of these filaments were as shown in Table 2. The performance of the yarn, such as conductivity, antistatic property, and metal abrasion resistance, was measured by the method shown in Example 1.

[Table] When the side surfaces of yarns Y ₅ to _{Y 8} were observed using a scanning electron microscope, it was observed that the surface irregularities caused by the conductive polymer were intermittent. In all cases, metal abrasion was low and no trouble occurred during the spinning, drawing, weaving, and weaving processes. _Y5 to _Y7 had good antistatic properties. _Y8 had a shape in which the conductive polymer did not have a thick part, but it had a high specific resistance value and poor antistatic properties.

[Brief explanation of drawings]

1 and 5 to 7 are schematic cross-sectional views of the composite fiber of the present invention. FIGS. 2, 3, and 8 are side-by-side type composite fibers, and FIG. 4 is a schematic cross-sectional view of a core-sheath type composite fiber. In the figure, 1 represents a non-conductive component, 2 represents a thick portion of the conductive component, and 3 represents a thin portion (band-shaped portion) of the conductive component. FIG. 9 and FIG. 10 are electron micrographs showing the cross section and side surface of the composite fiber (undrawn yarn) of the present invention.

Claims (1)

[Claims] 1 The specific resistance of the fiber-forming polymer is
It has a specific resistance of 10 ⁷ Ω・cm or more consisting of a non-conductive component of 10 ⁷ Ω・cm or more, a thermoplastic polymer, and inorganic conductive particles.
In a composite fiber with a conductive component of less than cm, the cross-sectional shape of the conductive component is a thick part wrapped in a non-conductive component, and at least a part of the fiber is connected to the thick part. An antistatic composite fiber comprising a bent tail extending to the periphery, and a conductive component is intermittently exposed on the fiber surface in a width of 1.5 μm or less.