Conductive composite fiber

Abstract

To provide an environmentally friendly novel conductive polyamide fiber having conductive performance equivalent to that of conventional petroleum-derived conductive fibers.SOLUTION: A conductive composite fiber is composed of, in a fiber cross section, a conductive layer and a non-conductive layer, wherein the non-conductive layer comprises polyamide 1010.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a conductive composite fiber comprising a non-conductive layer and a conductive layer, and more specifically to a conductive polyamide composite fiber in which the non-conductive component is made from a polymer raw material derived from biomass obtained from non-petroleum resources. [Background technology]

[0002] Conventionally, conductive composite fibers have generally been synthetic fibers made from synthetic resins derived from petroleum resources (for example, Patent Document 1).

[0003] However, with the recent increase in environmental awareness on a global scale, there is a strong demand for non-petroleum-derived fiber materials, even in the textile field. Meanwhile, attention is being paid to plant-derived plastics, i.e., biomass-derived plastics (hereinafter referred to as biomass plastics), as one means of preventing the future depletion of petroleum resources and global warming due to the mass consumption of petroleum resources. As an example of such a conductive polyamide composite fiber using biomass plastics, Patent Document 2 discloses a conductive polyamide fiber composed of polyamide having dicarboxylic acid units, the main component of which is sebacic acid units, and conductive carbon, with the conductive carbon content being 10 to 40 mass %. Specifically, Patent Document 2 discloses a conductive polyamide monofilament in which conductive carbon is kneaded into polyamide 610 or polyamide 510. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 57-11213 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-151782 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the conductive polyamide fibers described in Patent Document 2 are more environmentally friendly than petroleum-derived fibers, there is currently a demand for even more environmentally friendly materials, such as new, environmentally friendly conductive polyamide fibers. Therefore, an object of the present invention is to provide a novel conductive polyamide fiber that is environmentally friendly while having conductive performance equivalent to that of conventional petroleum-derived conductive fibers. [Means for solving the problem]

[0006] In order to achieve the above object, the gist of the present invention is a conductive composite fiber that has a conductive layer and a non-conductive layer in the fiber cross section, and the non-conductive layer is made of polyamide 1010. In the above-mentioned fibers, the relative viscosity of the polyamide 1010 is preferably 1.5 or more and 2.5 or less. In the above-mentioned fibers, the area ratio of the non-conductive layer / the conductive layer in the cross section of the fiber is preferably 45 / 55 to 98 / 2. In the above-mentioned fiber, it is more preferable that the mass ratio of the biomass-derived component of the entire fiber is 25% or more and 98% or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to obtain a novel conductive polyamide fiber that has conductive performance equivalent to that of conductive polyamide fiber made from petroleum-derived thermoplastic resin, even though the non-conductive layer uses a thermoplastic resin that is 100% biomass-derived. Furthermore, it is possible to obtain conductive polyamide fibers that are more environmentally friendly than conductive fibers in which conductive carbon is fully dispersed in PA610 or PA510. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an example showing a fiber cross section of a conductive conjugate fiber of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. The present invention is a conductive composite fiber comprising a conductive layer and a non-conductive layer.

[0010] The conductive layer is preferably formed from a thermoplastic resin containing conductive particles such as conductive carbon black or a white conductive agent.

[0011] The content of the conductive particles in the conductive layer varies depending on the type of conductive particles, the required conductive performance, etc., but is usually in the range of about 10 to 85 mass % and may be selected appropriately depending on the purpose.

[0012] When conductive carbon black is used as the conductive particles, the conductive layer is preferably made of a thermoplastic resin containing 15% by mass or more and 45% by mass or less of conductive particles. If the content of conductive carbon black in the thermoplastic resin is less than 15% by mass, the conductive fiber will have insufficient conductivity, making it difficult to improve the conductivity of the fiber structure when used in the fiber structure.If the content of conductive carbon black exceeds 45% by mass, the fluidity of the conductive layer will be significantly reduced, making it difficult to form fibers.

[0013] When a white conductive agent is used as the conductive particles, the conductive layer is preferably made of a thermoplastic resin containing 50% by mass or more and 80% by mass or less of conductive particles. If the content of the white conductive agent in the thermoplastic resin is less than 50% by mass, the conductive fiber will have insufficient conductivity, making it difficult to improve the conductive performance when used in a fiber structure.If the content of the white conductive agent exceeds 80% by mass, the fluidity of the conductive layer will be significantly reduced, making it difficult to form fibers.

[0014] Suitable examples of the thermoplastic resin include polyamide, polyester, and polyolefin. Examples of polyamides include polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 1010, and copolymer polyamides containing these as main components. Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene oxybenzoate, and copolymer polyesters containing these as main components. Examples of polyolefins include polyethylene, polybutylene, polypropylene, and copolymer polyesters containing these as main components.

[0015] The non-conductive layer is made from polyamide 1010. Although polyamide 1010 is a 100% biomass-derived resin, it has high fluidity when melted, allowing high-quality conductive composite fibers to be obtained. This allows for the production of environmentally friendly conductive fibers with strength and elongation properties and conductive performance equivalent to those of conventional conductive composite fibers made from polyamide 6. It also allows for the production of conductive fibers that are even more environmentally friendly than conductive fibers in which a portion of biomass-derived resin is dispersed throughout the fiber.

[0016] The relative viscosity of the polyamide 1010 used in the non-conductive layer is preferably 1.5 or more and 2.5 or less. Within this range, spinning is possible and the fiber properties are good. A more preferred range is 1.6 or more and 2 or less.

[0017] The conductive composite fiber of the present invention is obtained by combining the conductive layer and the non-conductive layer in the cross section of the fiber. The conductive layer is preferably continuous in the longitudinal direction of the fibers so that a conductive path is formed continuously in the longitudinal direction of the fibers.

[0018] An example of the fiber cross section of the conductive conjugate fiber of the present invention is shown in FIG. FIG. 1 shows a cross section of a core-sheath composite fiber, which has a conductive core layer (1) and a non-conductive sheath layer (2). Figure 1(a) shows a core-sheath composite fiber with a conductive layer (1) in the core and non-conductive layers (2) and (2') in the sheath. Specifically, it has a sandwich structure in which the non-conductive layer (2), conductive layer (1), and non-conductive layer (2') are arranged side-by-side in this order, sandwiching the conductive layer (1) between the non-conductive layers (2) and (2'). The conductive layer (1) is exposed in two places across the entire fiber surface and is sandwiched between the non-conductive layers (2) and (2'). In Figure 1(b), the conductive layer (1) is not exposed on the fiber surface, and a non-conductive layer (2) is arranged surrounding the conductive layer (1). The conductive layer (1) is the core, and the non-conductive layer (2) is the sheath, creating an eccentric core-sheath structure. The conductive composite fiber of the present invention uses polyamide 1010 for the non-conductive layer, and the conductive layer is concentrated to form a composite fiber that is continuous in the longitudinal direction.This makes it possible to obtain, for example, an environmentally friendly material with a small area of ​​the conductive layer exposed on the fiber surface, which allows for good processability while maintaining conductive performance.

[0019] The composite ratio of the non-conductive layer to the conductive layer is preferably 20:1 to 5:1 in mass ratio (non-conductive layer:conductive layer). From the viewpoint of ensuring the physical properties of the fiber, a larger ratio of the non-conductive layer is preferable, but as the ratio of the conductive layer decreases, it tends to become difficult to obtain a stable composite form, and as a result, the stability of the conductivity tends to decrease. Taking these factors into consideration, as described above, the ratio of the non-conductive layer to the conductive layer is preferably 20:1 to 5:1, and more preferably 15:1 to 10:1.

[0020] The area ratio of the non-conductive layer to the conductive layer in the fiber cross section, non-conductive layer / conductive layer, is preferably 45 / 55 to 98 / 2. From the viewpoint of ensuring the physical properties of the fiber, a larger ratio of the non-conductive layer is preferable, but as the ratio of the conductive layer decreases, it tends to become difficult to obtain a stable composite form, and as a result, the stability of the conductivity tends to decrease. Taking these factors into consideration, as described above, the non-conductive layer / conductive layer ratio is preferably 45 / 55 to 98 / 2, and more preferably 5 / 1 to 10 / 1.

[0021] In the conductive composite fiber of the present invention, the content of biomass-derived components in the entire fiber may be appropriately determined depending on environmental considerations and the desired conductive performance, but a mass ratio of 25% or more and 98% or less is usually preferred. Within this range, the fiber is environmentally friendly, provides conductive performance, and is easily fiberized. A mass ratio of 50% or more and 98% or less is more preferred. A mass ratio of 60% or more and 98% or less is even more preferred.

[0022] The fineness of the conductive conjugate fiber of the present invention is preferably 20 dtex or more and 400 dtex or less.

[0023] The number of filaments in the conductive conjugate fiber of the present invention is preferably 2 or more and 90 or less.

[0024] The electrically conductive conjugate fiber of the present invention preferably has a breaking strength of 0.5 cN / dtex or more and 6.0 cN / dtex or less, and a breaking elongation of 30% or more and 200% or less.

[0025] The hot water shrinkage of the conductive conjugate fiber of the present invention is preferably 5% or more and 15% or less. By using polyamide 1010 for the non-conductive layer to be combined with the conductive layer, the conductive conjugate fiber of the present invention can be a fiber with good dimensional stability and a lower hot water shrinkage than conventional conjugate fibers in which the non-conductive layer is made of petroleum-derived polyamide 6. This is expected to result in excellent post-processing properties, making it particularly useful for applications requiring dimensional stability.

[0026] The linear resistance value (temperature 20°C, humidity 30% RH) of the conductive composite fiber of the present invention is 10 3 That's it, 10 9 It is preferable that the resistivity is 10 Ω / cm or less. 11 Ω / cm. Within this range, stable productivity during spinning and processing and sufficient conductive performance can be obtained, and therefore, when the conductive conjugate fiber of the present invention is used in a fiber structure, it exhibits good antistatic properties.

[0027] The conductive conjugate fiber of the present invention may be a long fiber (filament) or a short fiber (staple).

[0028] The conductive conjugate fiber of the present invention can be suitably used for uniforms, curtains, carpets, dustproof clothing, conveyor belts, etc.

[0029] The method for producing the conductive composite fiber of the present invention is not particularly limited as long as the conductive composite fiber of the present invention can be obtained. For example, examples of the production method using melt spinning include a two-step method (a method in which an undrawn yarn is once wound up and then drawn), a method for producing a semi-drawn yarn in one step (a method for producing POY), a one-step high-speed spinning method (a method in which the spinning speed is set to a high speed of 4000 m / min or more and the drawing step is essentially omitted), and a high-speed spinning and drawing method (a method in which the spinning and drawing steps are carried out continuously). A particularly preferred method is the two-step method, and examples of the two-step method are described below. A thermoplastic resin containing conductive particles such as conductive carbon black or a white conductive agent, which is used for the conductive layer, and the above-mentioned polyamide 1010 resin, which is used for the non-conductive layer, are melted and extruded from the nozzle of the spinneret, cooled, oiled, and then wound up at a speed of 1000 m / min or less to obtain an undrawn yarn. Next, the obtained undrawn yarn is wound up at a draw ratio of 2 times or more and 3.5 times or less and at a hot drawing temperature of 190°C or less, and the linear resistance is measured at (temperature 20°C, humidity 30%RH) 10 3 ~10 9 It is possible to obtain drawn yarn (polyamide continuous fiber) with a strength of Ω / cm. [Example]

[0030] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below. The resins used in the present invention and the conductive fibers obtained in the examples and comparative examples of the present invention were determined by the following methods.

[0031] <Relative viscosity> The relative viscosity ηr of polyamide 1010 was determined by preparing a solution of 0.25 g of polyamide in 50 ml of m-cresol, passing the solution through an Ostwald viscometer at 25°C, and dividing the flow time of the solution by the flow time of the m-cresol. <Breaking strength, breaking elongation and strength-strain product> The breaking strength and breaking elongation of the conductive composite fiber were determined in accordance with JIS-L-1013 by measuring the strength and elongation at the time the sample broke under conditions of a sample length of 20 cm and a pulling rate of 20 cm / min using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation. The strength and elongation product was calculated from these values ​​using the following formula.

[0032]

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[0033] <Hot water shrinkage rate> The hot water shrinkage was determined in accordance with JIS L 1013.

[0034] <Evaluation of fiber conductivity (linear resistance value)> The linear resistance value (Ω / cm) was determined by taking a 10 cm length of conductive composite fiber, attaching aluminum foil to both ends of the fiber with a conductive adhesive, and measuring the resistance value (Ω) using a Hewlett-Packard High Resistance Meter 4339B, and dividing the measured resistance value by the distance between the electrodes (cm).

[0035] Example 1 The composite fiber was spun in a melt conjugate spinning machine using a spinneret that forms an eccentric core-sheath composite fiber (Figure 1(b)), in which the conductive core layer is a resin composition kneaded with 75% by mass of a white conductive agent and the non-conductive sheath layer is polyamide 1010 (manufactured by Daicel-Evonik). The relative viscosity of the sheath polyamide 1010 was 1.80. The spinneret had 48 holes, and the extruded composite fiber was treated as a single yarn. It was then passed through an oil application guide and a godet roller and wound as an undrawn yarn onto a bobbin rotating at 900 m / min. The wound undrawn yarn was then drawn in a twisting machine through a feed roller, a first roller at 96°C, and a second roller, with a difference in rotational speed between the first and second rollers to achieve a breaking elongation of approximately 40-60%. The undrawn yarn was then wound onto a pirn via a traveler, yielding a drawn yarn of 110 dtex / 48 f / cm conductive composite fiber. The area ratio of the non-conductive layer to the conductive layer in the cross section of the fiber was 10 / 1. The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in subsequent processes.

[0036] Example 2 The resin composition, consisting of polyamide 6 kneaded with 35% by mass of conductive carbon black, served as the core conductive layer, while polyamide 1010 (manufactured by Daicel-Evonik) served as the sheath nonconductive layer. Conjugate spinning was performed using a melt conjugate spinning machine with a spinneret that formed a sandwich-type core-sheath conjugate fiber (Figure 1(b)), in which the conductive layer was exposed at two points across the entire fiber surface and sandwiched between the nonconductive layers. The relative viscosity of the sheath polyamide 1010 was 1.80. The spinneret had 72 holes, and the extruded conjugate fiber was treated as a single yarn and passed through an oil application guide and a godet roller before being wound as an undrawn yarn onto a bobbin rotating at 600 m / min. The wound undrawn yarn was drawn through a draw twister using a feed roller, a first roller, and a second roller, with a difference in rotational speed between the first and second rollers to give a breaking elongation of about 40 to 60%, and then wound onto a pirn via a traveler to obtain a drawn yarn of conductive composite fiber with a thickness of 225 dtex / 72 f. The area ratio of the non-conductive layer to the conductive layer in the fiber cross section was 10 / 1. The obtained conductive composite fiber had excellent strength and elongation properties and was also excellent in passability in subsequent processes.

[0037] [Reference example 1] Conjugate spinning was performed using a melt conjugate spinning machine with a spinneret that forms an eccentric core-sheath conjugate fiber (Figure 1(b)), in which the conductive core layer was a resin composition kneaded with 75% by mass of a white conductive agent into polyethylene and the non-conductive sheath layer was polyamide 6. The spinneret had 48 holes, and the extruded conjugate fiber was treated as a single yarn. It was then passed through an oil application guide and a godet roller and wound as an undrawn yarn onto a bobbin rotating at 900 m / min. The wound undrawn yarn was then passed through a feed roller, a first roller at 96°C, and a second roller in a twisting machine, with a difference in rotational speed between the first and second rollers to achieve a breaking elongation of approximately 40-60%. The yarn was then wound onto a pirn via a traveler, yielding a drawn conductive conjugate fiber with a density of 110 dtex / 48 f. The area ratio of the non-conductive layer to the conductive layer in the fiber cross section was 10 / 1. The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in subsequent processes.

[0038] [Reference example 2] Conjugate spinning was performed using a melt conjugate spinning machine with a spinneret that formed a sandwich-type core-sheath conjugate fiber (Figure 1(b)) in which the conductive core layer was a resin composition kneaded with 35% by mass of conductive carbon black and the non-conductive sheath layer was polyamide 6. The conductive layer was exposed at two points across the entire fiber surface and sandwiched between the non-conductive layers. The spinneret had 72 holes, and the extruded conjugate fiber was passed through an oil application guide and a godet roller and wound as an undrawn yarn onto a bobbin rotating at 600 m / min. The wound undrawn yarn was then drawn through a feed roller, a first roller at 108 °C, and a second roller in a twisting machine, with a rotational speed difference between the first and second rollers to achieve a breaking elongation of approximately 40-60%. The drawn yarn was then wound onto a pirn via a traveler, yielding a 225 dtex / 72 f / cm conductive conjugate fiber. The area ratio of the non-conductive layer to the conductive layer in the fiber cross section was 10 / 1. The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in subsequent processes. Table 1 shows the structure and yarn properties of the conductive composite fibers obtained in the examples and comparative examples.

[0039] [Table 1]

[0040] The results in Table 1 show that the composite fibers obtained in the examples of the present invention were conductive composite fibers with excellent conductivity, strength and elongation, and dimensional stability. Therefore, it was possible to obtain biomass-derived conductive composite fibers with properties equivalent to those of conductive composite fibers derived from petroleum resources.

[0041] Furthermore, the polyamide 1010 that constitutes the non-conductive layer of the conductive fiber of the embodiment is a resin that is 100% derived from biomass, making it more environmentally friendly than conductive fibers that have conductive particles dispersed throughout the fiber cross section in PA610 or PA510, which are partially derived from biomass. [Industrial Applicability]

[0042] The conductive composite fiber of the present invention has high strength and elongation, and the resulting durability and processability, as well as high conductivity. Therefore, it can be used for uniforms, curtains, carpets, dustproof clothing, conveyor belts, etc. [Explanation of symbols]

[0043] 1 Conductive layer 2, 2' Non-conductive layer

Claims

1. A conductive composite fiber having a conductive layer and a non-conductive layer in the fiber cross section, wherein the non-conductive layer is polyamide 1010.

2. 2. The conductive fiber according to claim 1, wherein the relative viscosity of the polyamide 1010 is 1.5 or more and 2.5 or less.

3. 3. The conductive conjugate fiber according to claim 1, wherein the area ratio of the non-conductive layer to the conductive layer in the cross section of the fiber is 45 / 55 to 98 / 2.

4. 3. The conductive composite fiber according to claim 1, wherein the biomass-derived component of the entire fiber has a mass ratio of 25% or more and 98% or less.

5. 4. The conductive composite fiber according to claim 3, wherein the biomass-derived component of the entire fiber has a mass ratio of 25% or more and 98% or less.

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