JPH0157167B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a novel conductive composite fiber. Specifically, the present invention relates to conductive composite fibers that are not abrasive to metals and are easy to manufacture industrially. (Prior art) It is well known that fibers, especially hydrophobic fibers such as polyester, polyamide, polyacrylonitrile, and polyolefin, 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. Furthermore, fibers plated with metal or fibers coated with conductive substances have many disadvantages, such as extremely high production costs, often peeling off due to bending or friction during processing or use, and poor durability. 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, making it 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. 53-44579, Japanese Patent Publication No. 57-25647, etc. However, in composite fibers in which a conductive component containing conductive particles is completely encapsulated with a non-conductive component, the black or gray of carbon black or metal powder is relatively inconspicuous, but corona discharge occurs, causing dielectric breakdown of the sheath. However, it has the drawback of poor antistatic properties (for example, 3KV for loop pile carpet).
In order to guarantee the following frictional charging voltage, it is necessary to mix 2 to 3 times the amount of conductive fibers with exposed conductive components). In addition, composite fibers with a conductive component as a sheath and composite fibers in which a conductive component and a non-conductive component are joined side-by-side have excellent corona discharge properties, that is, antistatic properties, because the conductive component is exposed on the fiber surface. The black or gray color of carbon black and metal powder stands out, which lowers the quality of products made by mixing these composite fibers, and has the drawback of damaging other products due to friction. In contrast to black or gray conductive particles such as carbon black and metal powder, conductive particles with higher whiteness have been proposed in JP-A-54-161598 and JP-A-56-140028. It has now become possible to obtain fibers with relatively high whiteness even if they are exposed on the fiber surface. However, examples of highly white conductive particles include tin oxide, zinc oxide, indium oxide,
Examples include metal oxides such as titanium oxide, and when these metal oxide particles are mixed in large quantities to the extent that they provide sufficient electrical conductivity, they often seriously damage the object they rub against. For example, guides, knitting needles, heater plates, etc. used in yarn spinning, processing, weaving and knitting processes,
Furthermore, the spinning nozzle tends to be seriously damaged. Therefore, even when using conductive particles with high whiteness, a core-sheath type in which the conductive layer is not exposed on the surface is preferable from the viewpoint of abrasion resistance, but there are contradictory problems in that it is inferior from the viewpoint of antistatic property. (Problems to be Solved by the Invention) An object of the present invention is to reduce friction (contact) in the process of manufacturing conductive fibers and textile products containing the fibers.
The object of the present invention is to provide a conductive composite fiber that does not cause wear or damage to objects, is easy to manufacture industrially, and has excellent antistatic properties. (Means for Solving the Problems) The present inventors completed the present invention as a result of intensive research to improve the various defects of the conductive fibers. The present invention provides an electrically conductive material with a specific resistance of less than 10 ⁷ Ω·cm, which contains at least one electrically conductive particle selected from the group consisting of electrically conductive metal compound particles and inorganic particles having a film of a metal or electrically conductive metal compound. In conductive composite fibers that have a core component made of a thermoplastic polymer (A) and a sheath component made of two types of non-conductive thermoplastic polymers (B) and (C), the polymer (C) is part of the fiber. Polymers (A) and (B) are insoluble or poorly soluble in solvents or solutions that dissolve or decompose polymer (C), and are exposed on the surface and bonded to a part of polymer (A). The present invention relates to a conductive composite fiber characterized by: That is, the polymer (A) is a thermoplastic polymer containing at least one type of conductive particle selected from the group consisting of conductive metal compound particles and inorganic particles having a film of a metal or a conductive metal compound. It is insoluble or poorly soluble in the solvent or solution that dissolves or decomposes the polymer (C). The polymer (B) is a fiber-forming thermoplastic polymer, and like the polymer (A), it is insoluble or sparingly soluble in the solvent or solution. Polymer (C) is a thermoplastic polymer, and polymer (A)
It can be selected by the combination of and (B). As the 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, and highly white metal oxides and metal oxides can be used. Not only inorganic particles with a coating, but also metal powders (such as silver, nickel, copper, iron, aluminum, or alloys thereof), and metal compounds such as copper sulfide, copper iodide, zinc sulfide, and cadmium sulfide, which are relatively highly colored. can also be used. In other words, when used in white or light-colored products such as clothing or carpets, highly white metal oxides or inorganic particles with a metal oxide film, such as tin oxide or aluminum oxide mixed and fired with antimony oxide as the second component, should be used. Inorganic particles such as titanium oxide, magnesium oxide, silicon oxide, and aluminum oxide having a film of a conductive oxide such as tin oxide or zinc oxide can be used. Dust collection filters, printing/textile screens,
When used in products that do not require white color, such as static elimination brushes, metal powder, copper sulfide, copper iodide, etc.
Relatively highly colored metal compounds such as cadmium sulfide can 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 preferred. 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 to
Apply a pressure of Kg 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 particles having an average particle size of 1 to 2 μm are not unusable, those having an average particle size of 1 μm or less, particularly 0.5 μm or less, and most preferably 0.3 μm or less are used. However, if the diameter is less than 0.1μm, the dispersibility tends to be poor, so it is usually 0.1~
A particle size of 1 μm is suitable. The mixing ratio of conductive particles depends on the type of particles, conductivity,
It varies depending on the particle size, particle chain-forming ability, and the properties and crystallinity of the binder polymer to be mixed, but usually
The specific resistance (volume resistivity) of the conductive component forming the core is less than 10 ⁷ Ω・cm, although it is in the range of about 30 to 85% (by weight), and in many cases it is about 40 to 80%. It is necessary that the resistance be 10 ⁴ Ω・cm or less, and
Particularly preferred is 10 ² Ω·cm or less. Conductive polymer (core component) mixed with conductive particles
The polymer forming the is not particularly limited and can be arbitrarily selected. For example, there are many thermoplastic polymers such as polyamide, polyester, polyolefin, polyvinyl, and polyether, and fiber-forming polymers are preferred from the viewpoint of spinnability, but fiber-forming polymers used as one of the sheath components For example, (B) uses polyamides such as nylon 6, nylon 66, and nylon 12, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polyethylene and polypropylene, polyvinyl polymers such as polyvinyl chloride and polyacrylonitrile, polyurethane, etc. By doing so, a composite fiber with sufficiently good spinnability can be obtained. Generally, the above-mentioned polymers can be used for the polymer (B) constituting one of the sheath components, but it is better to use a polymer that is the same or of the same type as the polymer that forms the conductive polymer (A). This is preferable from the viewpoint of preventing peeling of the aggregate (B). However, the proportion of polymer (B) covering polymer (A) should be high, for example 60% or more, or a mutual affinity improving agent may be added to polymer (A) and/or polymer (B). Peeling can also be prevented by this. Furthermore, depending on the purpose of use, there may be cases where bending, friction, etc. are not involved, and even different types of polymers may be used satisfactorily. Examples of the mutual affinity improving agent include a copolymer of both, a polymer having one or both of terminal groups and/or side chain groups, and copolymers are generally used. For example, in the case of polyethylene and nylon, metal ion-containing ethylene-methacrylic acid copolymers such as ionomers are used, and in the case of polyamide and polyester, polyethers such as polyamide and polyalkylene glycol or polyesters such as polyalkylene terephthalate are used in block form. Examples include block polyether amide and block polyester amide bonded to The thermoplastic polymer used for the other polymer (C) constituting the sheath component must be selected depending on the combination of polymers (A) and (B). That is, polymer (A) is dissolved or decomposed in a solvent or solution that dissolves or decomposes polymer (C).
The combination must be such that (B) and (B) are insoluble or poorly soluble. For example, when polymers (A) and (B) are commonly used functional polymers (polyamide, polyester, polyacrylonitrile, polyvinyl chloride, polyolefin, polyurethane), an organic solvent such as benzene or toluene may be used. Polystyrene and its derivatives which are soluble in water, polyethylene glycol, polypropylene glycol, polyvinyl alcohol and their derivatives which are easily soluble in water or weak alkali can be used. Polymer (A)
When (B) and (B) are a combination of specific polymers, it is necessary to select appropriate polymers depending on the combination. For example, when polymers (A) and (B) are polyamides or polyolefins, polyesters, polyethers, and their derivatives that are soluble in alkaline aqueous solutions are used; In the case of vinyl, polyamides and their derivatives that are soluble in acids such as formic acid and hydrochloric acid are used, and in the case of polyurethane, polyesters, polyethers, or polyamides that are soluble in alkaline solutions are used. can. Polymers such as polyethylene glycol, polyesters and polyethers, polyamides and polyesters, even if polymers (A) and (B) are combinations of different polymers, such as polyamide and polyester, polyamide and polyolefin, polyacrylonitrile and polyvinyl chloride, etc. can be selected according to each combination. However, the operability of spinning etc. and polymer (C)
It is necessary to select an appropriate polymer by considering the dissolution or decomposition rate of the polymer. For example, when the combination of polymer (A) and polymer (B) is polyolefin and polyamide, polyvinyl alcohol, high molecular weight polyethylene glycol that is solid at room temperature, or a copolymer of polyethylene glycol and polyester can be used for spinnability. It is preferred because it is easily soluble in water or alkaline solutions, which makes it easy to handle.When the combination of polymer (A) and polymer (B) is polyester and polyolefin, it is soluble in acids such as sulfuric acid and hydrochloric acid. In addition to soluble polyamides such as nylon 6 and nylon 12, water-soluble polyvinyl alcohol and polyethylene glycol can also be used. Further, when the polymer (A) and the polymer (B) are a combination of polyamide and polyester, polystyrene is preferred, which is insoluble in acids and alkalis and soluble in organic solvents such as benzene and toluene. Furthermore, even polymers of the same type as polymers (A) and/or (B) can be used as long as the dissolution or decomposition rate is sufficiently higher than that of polymers (A) and (B). The dissolution or decomposition rate of polymer (C) differs depending on the composite ratio of polymer (A), (B), and (C), but the dissolution or decomposition rate of polymer (C) is different from that of polymer (A) and polymer (B).
It is necessary to have at least 3 times or more, more preferably 5 times or more, and most preferably 10 times or more. A core component consisting of a conductive polymer (A), a polymer (B) and
The composite ratio of the sheath component consisting of (C) is not particularly limited, but the composite ratio of the core component is usually 3 to 3.
It is 80%, preferably about 5 to 60%. On the other hand, the composite ratio of polymers (B) and (C) is usually 95/5 to 40/60.
However, it is necessary to choose the composite ratio depending on the usage situation. For example, when used in carpets and clothing that are subject to bending tension and friction, polymers
It is preferable to increase the ratio of (B), and when the polymer is used in a place that is hardly subjected to bending or friction, such as a filter, even if the ratio of polymer (B) is low, a product that can be used sufficiently can be obtained. This is because the polymer (C) is usually removed and used after it is made into products such as woven fabrics, knitted fabrics, nonwoven fabrics, and brushes. The cross-sectional shapes of the core component, sheath component, composite fibers, and their composite forms are shown in Figure 1 and Figures 3 to 8.
Although one example is shown in the figure, the shape and composite form can be selected as appropriate depending on the purpose of use without being limited to this. (Effects of the Invention) A major feature of the composite fiber of the present invention is that the polymer is
It is only necessary to remove (C), so it is necessary to remove the
There is no wear or damage to guides, needles, plate heaters, spinning nozzles, etc. due to exposure of conductive components during interwoven weaving, interwoven knitting, etc., and it can be manufactured industrially very easily and efficiently. In addition, during use, the polymer (C) is removed with a solvent or solution, and the conductive component of the polymer (A) is exposed, making it easy for electrostatic charges to move and corona discharge to occur. , can exhibit excellent antistatic properties. The composite fiber of the present invention is in the form of a continuous filament or staple and can be mixed with other chargeable fibers to impart antistatic properties to textile products. The mixing ratio is usually about 0.1 to 10%, but depending on the purpose, a mixing ratio of 10 to 100% or 0.1 or less may be applied. Mixtures include blended cotton, double yarn, double twisted yarn,
This can be done by blending, interweaving, interweaving, or any other known method. (Example) The effects of the present invention will be specifically explained below with reference to Examples. Parts and percentages indicate weight ratios unless otherwise specified. Example 1 A conductive powder obtained by mixing and firing 2% of antimony oxide fine particles (particle size of about 0.02 μm) on titanium oxide with an average particle size of 0.24 μm and forming a tin oxide film of about 12% by weight was prepared as A. Set to ₁ . The average particle size of powder _A1 is
It was 0.25 μm, had a specific resistance of 9 Ω·cm, had a reflectance of 82%, and had a slightly gray-blue color. Nylon 6 powder 25 with a molecular weight of approximately 16,000 and a melting point of 215℃
After mixing 75 parts of the conductive powder A _{1 and} 0.5 parts of magnesium stearate as a dispersant in powder form, the mixture was melt-kneaded twice using a twin-screw kneader to obtain conductive polymer CP ₁ . The volume resistivity of the obtained polymer CP ₁ was 1.5×10 ² Ω·cm. The same nylon 6 used in CP ₁ is made with a polymer containing 1.5% titanium oxide particles dispersed as a matting agent.
Let it be P ₁ . _P2 is a modified polyester copolymerized with 15% polyethylene glycol with a molecular weight of approximately 1000.
shall be. Composite spinning was carried out as shown in Fig. 1 using CP ₁ as the core component and P ₁ and P ₂ as the sheath components. Further, composite spinning was performed using CP ₁ as a conductive component and P ₁ as a protective component in a core/sheath and side-by-side type as shown in FIGS. 9 and 10. CP ₁ /
The composite ratio of P ₁ /P ₂ and CP ₁ /P ₁ is 10/80/10 and
I gave it a score of 10/90. Melt composite three or two components at 280℃ diameter
The yarn was spun through a 0.25 mm orifice, cooled, oiled, and wound at a speed of 800 m/min to obtain undrawn yarns UY ₁ to UY ₃ of 55 denier/3 filaments. Stretching undrawn yarn UY ₁ to _{UY 3} at a stretching ratio of 2.2 times, 85℃
The yarn was stretched using a heating roller, heat-set under tension at 170°C, and then wound to obtain drawn yarns Y ₁ to Y ₃ of 25 denier/3 filaments. The obtained yarns Y ₁ to _{Y 3} were each knitted into a circular knit fabric made of nylon 6 ordinary yarn (210 denier/54 filaments) at intervals of about 6 mm, and after removing the spinning oil with a surfactant, the yarns were heated at 95°C.
Polymer by treatment with 2% sodium hydroxide aqueous solution
Knitted fabrics _K1 to _K3 from which _P2 was almost completely removed were obtained. still,
As a control, a knitted fabric containing no conductive yarn was prepared and subjected to the same treatment to obtain knitted fabric _K4 . The resulting knitted fabric K ₁ ~ _{K 4}
After washing thoroughly with water and drying at 80℃ for 3 hours,
Humidity was controlled for 6 hours in an atmosphere of 25℃ and 33%RH.
Frictional charging voltage was measured in the same atmosphere. The measurement was carried out by the method proposed by the present inventors in JP-A-56-48550, and cotton cloth was used as the friction cloth. The electrostatic voltage was read after 10 seconds of friction. The results are shown in Table 1 together with the drying efficiency in spinning and drawing the conductive yarn.

[Table] Yarn Y ₃ with conductive components exposed on the fiber surface is
During spinning, the yarn was bent at the point where it exited the orifice, causing yarn breakage, and during stretching and winding, the traveler was significantly worn and yarn breakage occurred frequently, so that only 3 to 500 g could be wound. Furthermore, wear was also observed on the plate heater for heat fixation. Yarn _Y2 , in which the conductive component was completely encapsulated, had good operability, but its antistatic properties were not satisfactory. Example 2 70 parts of conductive particles _A1 used in Example 1 and molecular weight approx.
80 parts of low density polyethylene having a melting point of 102° C. and a melting point of 102° C. were melt-kneaded in powder form using a twin-screw kneader to obtain a conductive polymer CP ₂ . The resulting polymer CP ₂ was obtained.
The volume resistivity of the obtained polymer CP ₂ is 6.8 × 10 ²
It was Ω・cm. 60 parts of fine nickel powder with an average particle size of 2 μm produced by thermally decomposing nickel tetracarbonyl and nylon 6 with a molecular weight of approximately 17,000 and a melting point of 215°C.
40 parts in powder form, or an average particle size of 0.22 μm obtained by mixing aluminum oxide and aluminum monoxide with an average particle size of 0.02 μm with zinc oxide powder having an average particle size of 0.15 μm, firing it, and then finely pulverizing it. , 75 parts of electrically conductive zinc oxide fine powder with a volume resistivity of 20 Ω・cm, 25 parts of polyethylene terephthalate with a molecular weight of about 16,000 and a melting point of 257°C, and 0.5 parts of a polyethylene oxide/polypropylene oxide block copolymer as a dispersant.
The mixture was melt-kneaded using the same twin-screw kneader as above to obtain conductive polymers CP ₃ and CP ₄ . 0.6 parts of titanium oxide fine particles to 100 parts of polyethylene terephthalate with a molecular weight of approximately 16,000 and a melting point of 257°C.
Let the partially dispersed polymer be _P3 . Melt flow syndex is 24g/10min (200
℃, load 5 kg) is assumed to be polystyrene _P4 . Polyethylene oxide with an average molecular weight of about 20,000 and a freezing point of about 60°C is designated as _P5 . Conductive polymers CP ₂ to CP ₄ and polymers P ₁ to _{P 5}
Composite spinning was performed using a composite shape as shown in FIG. 6, and four types of yarns Y ₄ to _{Y 7} were obtained. The combinations and composite ratios of the conductive polymer (A) and the polymers (B) and (C) are shown in Table 2.

[Table] Spinning and drawing were performed in the following manner. The three molten components are combined in a spinning pack, spun from a 0.25mm diameter foliage, cooled and oiled.
It was rolled up at a speed of 1000m/min. However, the spinning temperature was 270°C for yarn _Y4 and 285°C for yarns Y5 _{to 7} . The resulting undrawn yarns were stretched 2.2 times using a heated roller at 85°C and heat-set on a heat plate at 170°C to form drawn yarns of 30 denier/5 filaments.
_Y4 to _Y7 were obtained. In either case, there were no troubles during the process to obtain drawn yarn (such as yarn breakage during spinning and drawing, wear of guides, rollers, heater plates, etc.), and the operability was almost the same as that of ordinary yarn. The obtained yarn was made into circular knitted fabric _K4 in the same manner as in Example 1.
~ Created _K7 . After removing the spinning oil from the obtained circular knitted fabric with a surfactant, _K4 and _K5 were heated to 2% at 95°C.
of sodium hydroxide solution, _K6 is toluene,
In K ₇ , the polymer (C) was almost completely removed with hot water at 98°C. The circular knitted fabrics K ₄ to _{K 7} from which the polymer (C) had been removed were thoroughly washed with water, and the frictional charging voltage was measured in the same manner as in Example 1. As shown in Table 3, all of them had excellent antistatic properties.

[Table] Polymers (A) and (B) used for yarn Y ₅ and polymers
Both (C) are decomposed in alkaline aqueous solution, but
The decomposition rate for an alkaline aqueous solution is 1 for the former and approximately 50 for the latter, meaning that polymers (B) and (C) are hardly decomposed in the time it takes to almost completely decompose polymer (C), and their strength decreases. No decrease was observed.

[Brief explanation of drawings]

FIGS. 1 and 3 to 8 are specific examples of cross sections of the composite fibers of the present invention. However, FIG. 2 is a specific example of a cross section after removing the polymer (C) in the composite fiber of FIG. 1. FIGS. 9 and 10 are examples of cross sections of conventional two-component composite fibers. In the figure, 1 is a conductive polymer (A), and 2 is a non-conductive polymer (B).
3 indicates a non-conductive polymer (C).

Claims (1)

[Claims] 1. A conductive thermoplastic polymer having a specific resistance of less than 10 ⁷ Ω・cm and containing at least one kind of conductive particle selected from the group consisting of conductive metal compound particles and inorganic particles having a film of a metal or a conductive metal compound. Combine (A)
as a core component, two types of non-conductive thermoplastic polymers (B) and
In conductive composite fibers containing (C) as a sheath component, part of the polymer (C) is exposed on the fiber surface, and the polymer (A)
Polymers (A) and (B) in a solvent or solution that dissolves or decomposes polymer (C).
A conductive composite fiber characterized by being insoluble or hardly soluble.