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 composed of a non-conductive layer and a conductive layer. More specifically, it relates to a conductive polyamide composite fiber in which the non-conductive component is composed of a polymer raw material derived from biomass obtained from non-petroleum resources.

Background Art

[0002] Conventionally, as conductive composite fibers, synthetic fibers using synthetic resins derived from petroleum resources are common (for example, Patent Document 1).

[0003] However, with the recent increase in global environmental awareness, there is a strong demand for non-petroleum-derived fiber materials in the fiber field. On the other hand, as one of the means to suppress future depletion of petroleum resources and global warming caused by massive consumption of petroleum resources, attention has been focused on plant-derived plastics, that is, plastics derived from biomass (hereinafter referred to as biomass plastics). As such a conductive polyamide composite fiber using biomass plastics, for example, Patent Document 2 discloses a conductive polyamide fiber composed of a polyamide having a dicarboxylic acid unit having sebacic acid units as a main component and conductive carbon, and the content of conductive carbon is 10 to 40% by mass. Specifically, conductive polyamide single fibers in which conductive carbon is kneaded into polyamide 610 and polyamide 510 are disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, while the conductive polyamide fibers described in Patent Document 2 are more environmentally friendly than petroleum-derived fibers, there is currently a need for even more environmentally friendly conductive polyamide fibers. Therefore, the present invention aims 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] To achieve the above objective, the present invention relates to a conductive composite fiber comprising a conductive layer and a non-conductive layer in the cross-section of the fiber, wherein the non-conductive layer is polyamide 1010. In the above-mentioned fibers, it is preferable that the relative viscosity of polyamide 1010 is 1.5 or higher and 2.5 or lower. In the above-mentioned fibers, it is preferable that the area ratio of the non-conductive layer to the conductive layer in the fiber cross-section is 45 / 55 to 98 / 2. In the above-mentioned fibers, it is even more preferable that the biomass-derived components of the entire fiber account for 25% or more and 98% or less by mass. [Effects of the Invention]

[0007] According to the present invention, a novel conductive polyamide fiber can be obtained that has the same conductivity as conductive polyamide fibers made of petroleum-derived thermoplastic resin, even though a 100% biomass-derived thermoplastic resin is used for the non-conductive layer. Furthermore, it is possible to obtain conductive polyamide fibers that are more environmentally friendly than conductive fibers in which conductive carbon is completely dispersed in PA610 or PA510. [Brief explanation of the drawing]

[0008] [Figure 1] This is an example showing the fiber cross-section of the conductive composite fiber of the present invention. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below. The present invention relates to 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 and a white conductive agent.

[0011] The content of conductive particles in the conductive layer varies depending on the type of conductive particles and the required conductivity, but it is usually within the range of 10 to 85% by mass, and should be selected appropriately according to the purpose.

[0012] When conductive carbon black is used as the conductive particles, it is preferable to use a thermoplastic resin as the conductive layer, which contains 15% by mass or more and 45% by mass or less of conductive particles in the conductive layer. If the conductive carbon black content in thermoplastic resin is less than 15% by mass, the conductive performance of the conductive fibers tends to be insufficient, making it difficult to achieve good conductivity when used in fibrous structures. If the conductive carbon black content exceeds 45% by mass, the fluidity of the conductive layer decreases significantly, making it difficult to form fibers.

[0013] When a white conductive agent is used as the conductive particles, it is preferable to use a thermoplastic resin as the conductive layer, which contains 50% by mass or more and 80% by mass or less of conductive particles in the conductive layer. If the content of the white conductive agent in the thermoplastic resin is less than 50% by mass, the conductive performance of the conductive fibers tends to be insufficient, making it difficult to achieve good conductivity when used in fibrous structures. If the content of the white conductive agent exceeds 80% by mass, the fluidity of the conductive layer decreases significantly, making it difficult to form fibers.

[0014] Suitable thermoplastic resins include, for example, polyamides, polyesters, and polyolefins. Examples of polyamides include polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 1010, and copolyamides having these as the main components. Examples of polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene oxybenzoate, and copolyesters having these as the main components. Examples of polyolefins include polyethylene, polybutylene, polypropylene, and copolyesters having these as the main components.

[0015] The non-conductive layer is formed from polyamide 1010. Despite being a 100% resin derived from biomass, polyamide 1010 has high fluidity during melting, and conductive composite fibers with good quality can be obtained. As a result, environmentally friendly conductive fibers having tensile strength and elongation properties equivalent to those of the conductive composite fibers of conventional polyamide 6 and conductive performance can be obtained. Also, more environmentally friendly conductive fibers can be obtained compared to conductive fibers in which a part of the resin derived from biomass is dispersed throughout the fiber.

[0016] The relative viscosity of polyamide 1010 used for the non-conductive layer is preferably 1.5 or more and 2.5 or less. Within this range, it is spinable and the fiber physical properties are also good. More preferably, it is 1.6 or more and 2 or less.

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

[0018] An example of the fiber cross-section of the conductive composite fiber of the present invention is shown in FIG. 1. FIG. 1 is a fiber cross-section of a core-sheath composite fiber in which the core is a conductive layer (1) and the sheath is a non-conductive layer (2). Figure 1(a) shows a core-sheath composite fiber in which a conductive layer (1) is arranged in the core and non-conductive layers (2) and (2') are arranged in the sheath. Specifically, it is a sandwich shape in which the non-conductive layers (2) and (2') are arranged side-by-side in the order of non-conductive layer (2), conductive layer (1), and non-conductive layer (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'). Figure 1(b) shows that the conductive layer (1) is not exposed on the fiber surface, and the non-conductive layer (2) is arranged around the conductive layer (1). This is an eccentric core-sheath shape where the conductive layer (1) is the core and the non-conductive layer (2) is the sheath. The conductive composite fiber of the present invention uses polyamide 1010 as the non-conductive layer, and the conductive layer is concentrated, resulting in a composite fiber that is continuous in the longitudinal direction. For example, it is possible to obtain an environmentally friendly material with a small surface area of ​​the conductive layer exposed on the fiber surface, while maintaining conductive performance and offering good processability.

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

[0020] The area ratio of the non-conductive layer to the conductive layer in the fiber cross-section is preferably 45 / 55 to 98 / 2. From the viewpoint of ensuring the physical properties of the fiber, a larger proportion of the non-conductive layer is preferable, but if the proportion of the conductive layer is small, it tends to become difficult to obtain a stable composite form, and consequently, the stability of 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] The biomass-derived component content of the conductive composite fiber of the present invention may be appropriately determined according to environmental considerations and the desired conductive performance, but it is generally preferable that the mass ratio is 25% or more and 98% or less. Within this range, it is environmentally friendly, conductive performance can be obtained, and it is easy to process into fibers. More preferably, it is 50% or more and 98% or less. Even more preferably, it is 60% or more and 98% or less.

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

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

[0024] The tensile strength of the conductive composite fiber of the present invention is preferably 0.5 cN / dtex or more and 6.0 cN / dtex or less. Furthermore, the elongation at break is preferably 30% or more and 200% or less.

[0025] The conductive composite fiber of the present invention preferably has a hot water shrinkage rate of 5% or more and 15% or less. By using polyamide 1010 as the non-conductive layer combined with the conductive layer, the conductive composite fiber of the present invention can be made into a fiber with a lower hot water shrinkage rate and better dimensional stability than conventional composite fibers in which the non-conductive layer is combined with petroleum-derived polyamide 6. As a result, it is expected that post-processability will also be excellent, making it particularly useful for applications where dimensional stability is required.

[0026] The linear resistance value of the conductive composite fiber of the present invention (at a temperature of 20°C and a humidity of 30%RH) is 10 3 The above 10 9 It is preferable that the density is Ω / cm or less. Typically, the upper limit is 10 11 It is Ω / cm. Within this range, stable productivity during spinning and processing, as well as sufficient conductive performance, can be obtained. Therefore, the conductive composite fibers of the present invention exhibit good antistatic properties when used in fiber structures.

[0027] The conductive composite fibers of the present invention may be long fibers (filaments) or short fibers (staples).

[0028] The conductive composite fibers of the present invention can be suitably used in uniforms, curtains, carpets, dustproof clothing, conveyor belts, and the like.

[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, regarding the melt spinning method, examples include a two-step method (a method in which the undrawn yarn is wound up once and then drawn), a method for producing 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 high, such as 4000 m / min or more, and substantially omits the drawing step), and a high-speed spinning and drawing method (a method in which the spinning and drawing steps are performed continuously). A particularly preferred method is the two-step process. An example of a two-step manufacturing method is described below. A thermoplastic resin containing conductive particles such as conductive carbon black or a white conductive agent for the conductive layer and the polyamide 1010 resin for the non-conductive layer are melted and extruded from the nozzle discharge hole. After cooling and lubrication, the mixture is wound up at a speed of 1000 m / min or less to obtain undrawn yarn. Next, the obtained undrawn yarn is wound up at a draw ratio of 2x or more and 3.5x or less, and a heat-drawn temperature of 190°C or less, and the wire resistance value is (at 20°C and 30% RH) 10 3 ~10 9 A drawn yarn (polyamide long fiber) with a density of Ω / cm can be obtained. [Examples]

[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 resin used in the present invention, and the conductive fibers obtained in the examples and comparative examples of the present invention, were obtained by the following methods.

[0031] <Relative viscosity> The relative viscosity ηr of polyamide 1010 was determined by preparing a solution by dissolving 0.25 g of polyamide in 50 ml of m-cresol, passing it 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, elongation at breaking, and strength-elongation product> The breaking strength and breaking elongation of conductive composite fibers are defined in JIS. L In accordance with 1013, the strength and elongation of the sample at the point of tensile fracture were measured using a Shimadzu AGS-1KNG Autograph tensile testing machine under the conditions of a sample yarn length of 20 cm and a tensile speed of 20 cm / min. The strength-to-elongation product was then calculated from these values ​​using the following formula.

[0032]

number

[0033] <Heat shrinkage rate> The thermal shrinkage rate was determined in accordance with JIS L 1013.

[0034] <Evaluation of fiber conductivity (linear resistance value)> The line resistance was calculated by taking a 10 cm section of conductive composite fiber, attaching aluminum foil to both ends with conductive adhesive, and measuring the resistance (Ω) using a Hewlett-Packard 4339B high-resistance meter. The resistance value was then divided by the distance between the electrodes (cm) to obtain the line resistance value (Ω / cm).

[0035] [Example 1] A resin composition prepared by kneading polyethylene with 75% by mass of a white conductive agent was used as the conductive core layer, and polyamide 1010 (manufactured by Daicel-Evonik) was used as the non-conductive sheath layer. Composite spinning was performed using a spool that formed an eccentric core-sheath type composite fiber as shown in Figure 1(b), where the conductive layer is not exposed on the fiber surface. The relative viscosity of the polyamide 1010 sheath was 1.80. The spool had 48 holes, and the extruded composite fiber was wound as an undrawn yarn onto a bobbin rotating at 900 m / min via an oil-applying guide and a godet roller. The wound undrawn yarn was drawn in a twisting machine via a feed roller, a 96°C first roller, and a second roller, with a difference in rotation speed between the first and second rollers so that the elongation at break was approximately 40-60%. The yarn was then wound onto a pan via a traveler to obtain a drawn conductive composite fiber yarn of 110 dtex / 48f. Furthermore, the area ratio of the non-conductive layer to the conductive layer in the fiber cross-section was set to 10 / 1. The resulting conductive composite fibers exhibited excellent strength and elongation, as well as superior passability in subsequent processes.

[0036] [Example 2] A resin composition made by kneading 35% by mass of conductive carbon black into polyamide 6 is used as the core conductive layer, and polyamide 1010 (manufactured by Daicel-Evonik) is used as the sheath non-conductive layer, resulting in a sandwich-type structure where the conductive layer is exposed at two points across the entire fiber surface and sandwiched between the non-conductive layers (Figure 1). a Composite spinning was performed using a melt-compound spinning machine with a die that forms core-sheath type composite fibers. The relative viscosity of the polyamide 1010 in the sheath was 1.80. The die had 72 holes, and the extruded composite fiber was wound as an undrawn yarn onto a bobbin rotating at 600 m / min via an oil-applying guide and a godet roller. The wound undrawn yarn was drawn in a twisting machine via a feed roller, a first roller, and a second roller, with a difference in rotational speed between the first and second rollers so that the elongation at break was approximately 40-60%, and then wound onto a pan via a traveler to obtain a drawn conductive composite fiber yarn of 225 dtex / 72 f. The area ratio of the non-conductive layer to the conductive layer in the fiber cross-section was set to 10 / 1. The resulting conductive composite fibers exhibited excellent strength and elongation properties, as well as superior passability in subsequent processes.

[0037] [Reference example 1] A resin composition prepared by kneading polyethylene with 75% by mass of a white conductive agent was used as the conductive core layer, and polyamide 6 as the non-conductive sheath layer. Composite spinning was performed using a spool that formed an eccentric core-sheath type composite fiber as shown in Figure 1(b), where the conductive layer is not exposed on the fiber surface. The spool had 48 holes, and the extruded composite fiber was wound as an undrawn yarn onto a bobbin rotating at 900 m / min via an oil-applying guide and a godet roller. The wound undrawn yarn was drawn in a twisting machine via a feed roller, a first roller at 96°C, and a second roller, with a difference in rotation speed between the first and second rollers so that the elongation at break was approximately 40-60%. The yarn was then wound onto a pan via a traveler to obtain a drawn conductive composite fiber yarn of 110 dtex / 48 f. The area ratio of the non-conductive layer to the conductive layer in the fiber cross-section was set to 10 / 1. The resulting conductive composite fibers exhibited excellent strength and elongation, as well as superior passability in subsequent processes.

[0038] [Reference example 2] A resin composition made by kneading 35% by mass of conductive carbon black into polyamide 6 is used as the core conductive layer, and polyamide 6 is used as the sheath non-conductive layer, resulting in a sandwich-type structure where the conductive layer is exposed at two points across the entire fiber surface and sandwiched between the non-conductive layers (Figure 1). a Composite spinning was performed using a melt-compound spinning machine with a die that forms core-sheath type composite fibers. The die had 72 holes, and the extruded composite fibers were wound as undrawn yarn onto a bobbin rotating at 600 m / min via an oil-applying guide and a godet roller. The wound undrawn yarn was drawn in a twisting machine via a feed roller, a first roller at 108°C, and a second roller, with a difference in rotational speed between the first and second rollers so that the elongation at break was approximately 40-60%, and then wound onto a pan via a traveler to obtain drawn conductive composite fiber yarn of 225 dtex / 72 f. The area ratio of the non-conductive layer to the conductive layer in the fiber cross-section was set to 10 / 1. The resulting conductive composite fibers exhibited excellent strength and elongation, as well as superior passability in subsequent processes. Table 1 shows the composition and filamentous properties of the conductive composite fibers obtained in the examples and comparative examples.

[0039] [Table 1]

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

[0041] Furthermore, since the polyamide 1010 that constitutes the non-conductive layer of the conductive fiber in the example is a 100% biomass-derived resin, it is more environmentally friendly than conductive fibers in which conductive particles are dispersed throughout the entire fiber cross-section using PA610 and PA510, which are partially biomass-derived resins. [Industrial applicability]

[0042] The conductive composite fiber of the present invention possesses strength and elongation, and consequently durability and process passability, as well as conductivity. It is excellent. Therefore, it can be used in 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 in the core and a non-conductive layer in the sheath in the fiber cross-section, wherein the non-conductive layer is polyamide 1010.

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

3. A conductive composite fiber according to claim 1 or 2, 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. The conductive composite fiber according to claim 1 or 2, wherein the biomass-derived components of the entire fiber constitute 25% or more and 98% or less by mass.

5. The conductive composite fiber according to claim 3, wherein the biomass-derived components of the entire fiber constitute 25% or more and 98% or less by mass.

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