JP6752755B2 - Polyamide-based conductive composite fiber - Google Patents

Description

The present invention relates to polyamide-based conductive composite fibers.

Conductive fibers are often used for uniforms of flammable hazardous materials handlers, dust-proof clothing for clean rooms, carpets, curtains, etc., mainly for the purpose of preventing sparks and clinging of dust due to static electricity. When used for such fabrics, conductive fibers are inserted in a grit or stripe shape at a pitch of several mm to several cm, and these fabrics are stably controlled even in various environments such as low temperature and low humidity. Electrical performance is required.
As conductive fibers used for such fabrics, for example, metal fibers made of metal itself, metal-plated fibers obtained by plating general fibers with metal, and general fibers obtained by melting or solution-coating a conductive substance kneaded resin. Examples thereof include conductive coating fibers, conductive composite fibers obtained by melt-compositing spinning a kneaded resin composition of a conductive substance and a thermoplastic resin. Above all, conductive carbon black is used in consideration of antistatic performance that does not cause sparks, texture when made into fabric, corrosion resistance, chemical resistance, stretch resistance, abrasion resistance, washing durability, manufacturing cost, etc. Conductive composite fibers are most preferred and used. In the fiber cross section of such a conductive composite fiber, a non-exposed type in which the conductive layer is completely wrapped in the non-conductive layer and an exposure in which the conductive layer is exposed to a part of the fiber surface or the entire fiber surface. There are types, and conductive composite fibers with various fiber cross sections are used depending on the application. (Patent Document 1, Patent Document 2, Patent Document 3)

Japanese Unexamined Patent Publication No. 2014-133950 JP-A-11-65226 International Publication WO01 / 021867

By the way, a carbon black-containing resin composition as a conductive layer is arranged in the cross section of the fiber, and a resin as a non-conductive layer and a strength-retaining layer is arranged and melt-composite spun to obtain a conductive composite fiber, which contains carbon black. Since the resin composition has low melt fluidity, the strength and elongation of the conductive composite fiber are remarkably inferior, and the process passability and durability are inferior. Therefore, various measures have been taken. In particular, regarding the strength and elongation of the conductive composite fiber, which is related to the passability and durability in the post-process, for example, when a polyamide having a high viscosity among the polyamides generally excellent in strength and being listed as a flexible resin is used for the strength retaining layer. The strength is further improved, and the process passability is also excellent. However, when high-viscosity polyamide is used for the strength-retaining layer, the shrinkage rate and shrinkage stress of the composite fiber become high, so that the dimensional stability is inferior. When it is passed through a process such as finishing heat setting, the portion of the conductive composite fiber in the fabric is strongly shrunk, and wrinkles appear to be wavy in the entire fabric, resulting in inferior quality.
In view of the above problems, the present invention has excellent conductivity and conductivity in polyamide-based conductive composite fibers, and also has excellent dimensional stability that does not cause wrinkles when mixed with polyester yarn to form a fabric. The purpose is to obtain sex composite fibers.

In order to achieve the above object, the present invention is a conductive composite fiber composed of a conductive layer and a non-conductive layer serving as a strength retaining layer in the cross section of the fiber, and the conductive layer contains 15% by mass or more of conductive carbon black. , 45% by mass or less of the polyamide, and the non-conductive layer is a conductive composite fiber which is a polyamide obtained by polycondensation of metaxylene diamine and an aliphatic dicarboxylic acid.
In the conductive composite fiber, the polyamide of the conductive layer is preferably polyamide 6, polyamide 12, or polyamide 66.
Further, in the conductive composite fiber, the area ratio of the non-conductive layer / conductive layer in the cross section of the fiber is preferably 30/70 to 98/2.

The conductive composite fiber of the present invention is excellent in strong elongation and conductivity, and even when mixed with polyester yarn, it is possible to obtain a high-quality fabric without defects such as wrinkles after processing.

Hereinafter, the present invention will be described in detail.
The present invention is a conductive composite fiber composed of a conductive layer and a non-conductive layer serving as a strength retaining layer.
The non-conductive layer is made of a polyamide obtained by polycondensation of metaxylylenediamine and an aliphatic dicarboxylic acid.

In the present invention, the polyamide constituting the non-conductive layer is a polyamide obtained by polycondensation of metaxylene diamine and an aliphatic dicarboxylic acid. For example, polyamide MXD6 and metaxylene obtained by polycondensation of metaxylene diamine and adipic acid. Polyamide MXD8 obtained from polycondensation of diamine and sebacic acid is preferably mentioned. These are generally available as the MX nylon series of Mitsubishi Gas Chemical Company, Inc.

The conductive layer of the conductive composite fiber of the present invention is a polyamide containing 15% by mass or more and 45% by mass or less of conductive carbon black.

In the present invention, the thermoplastic resin serving as the base polymer constituting the conductive layer is polyamide.
Examples of such a polyamide include polyamide 6, polyamide 66, polyamide 12, polyamide 11, polyamide 66 and a copolymer containing them as a main component, and among them, polyamide 6, polyamide 66 and polyamide 12 are preferable.

In the conductive composite fiber of the present invention, the conductive layer contains 15% by mass or more and 45% by mass or less of conductive carbon black. If the amount of carbon black is too small, conductivity and antistatic properties cannot be obtained, and if it is too large, fluidity tends to be lost during spinning and the spinning property tends to deteriorate. Above all, the content of carbon black is preferably 20% by mass or more and 40% by mass or less.

In the present invention, examples of the conductive carbon black used for the conductive layer include Ketjen black, furnace black, and acetylene black, and the present invention is not particularly limited as long as it is a carbon black having excellent conductivity.

The methods for incorporating the conductive carbon black into the conductive layer in the present invention include (1) a method of mixing the conductive carbon black and the resin at the time of melt composite spinning, and (2) a resin serving as the base polymer with the conductive carbon black in advance. Is kneaded to obtain a resin composition of conductive carbon black and a base polymer, and then this resin composition is melt-composite spun to form a conductive layer. The latter is preferable.

In the conductive composite fiber of the present invention, the area ratio of the non-conductive layer / conductive layer in the cross section of the fiber is preferably 30/70 to 98/2. If it is out of this range, sufficient conductivity cannot be obtained, and when it is used for a fabric, not only the antistatic property is impaired, the yarn strength is remarkably lowered, but also the yarn breakage may occur frequently. More preferably, the area ratio of the non-conductive layer / conductive layer is 50/50 to 95/5. In the present invention, the fiber cross section refers to a plane perpendicular to the fiber axis longitudinal direction.

The cross-sectional shape of the conductive composite fiber of the present invention is either a non-exposed type in which the conductive layer is completely wrapped in the non-conductive layer, or an exposed type in which the conductive layer is exposed to a part of the fiber surface or the entire fiber surface. It may be. In particular, the exposed type exposed on the entire fiber surface usually has difficulty in obtaining strong elongation, but the conductive composite fiber of the present invention can obtain sufficient strong elongation and is mixed with polyester yarn. As a cloth, it is possible to obtain a high-quality cloth without wrinkles.
In the conductive composite fiber of the present invention, from the viewpoint of excellent antistatic property, an exposed type that is exposed on the entire surface of the fiber is preferable, and a non-conductive layer on the core and a conductive layer on the sheath are preferable.

Even if the conductive composite fiber of the present invention is used for a fabric combined with polyester yarn, it does not wrinkle during processing and can be suitably used for dust-proof clothing for clean rooms, work clothing, and the like.

Further, the conductive composite fiber of the present invention is mixed with a woven or knitted fabric to form an antistatic fabric, and can be suitably used for uniforms, dustproof clothing for clean rooms, carpets, and curtains. It may be shortened into a spun yarn or a non-woven fabric, or it may be used as a conductive brush utilizing conductivity, a pen tip for a touch panel, or a glove.

An example of a suitable manufacturing method of the conductive composite fiber of the present invention is shown.
The above-mentioned conductive carbon black and the above-mentioned polyamide are prepared and kneaded to produce a resin composition. A melt composite spinning is performed by using the obtained resin composition as a conductive layer and polyamide MXD6 or polyamide MXD8 as a non-conductive layer, and using a composite base that discharges the conductive layer and the non-conductive layer in a composite state in a fiber cross section. To produce a conductive composite fiber.

The present invention will be specifically described below with reference to examples. The present invention is not limited to the examples described below. The characteristics and evaluation of the conductive fibers and the fabric made of the conductive fibers obtained in the examples and comparative examples of the present invention were obtained by the following methods.

<Relative viscosity of polyamide ηr>
For the relative viscosity ηr in 96.0% sulfuric acid, prepare a solution in which 0.5 g of polyamide is dissolved in 50 ml of 96.0% sulfuric acid, pass it through an Ostwald viscometer at 25 ° C., and allow the flow time of the solution to flow down the sulfuric acid. Obtained by dividing by time.
<Production of breaking strength, breaking elongation and strong elongation>
The breaking strength and breaking elongation of the conductive composite fiber are in accordance with JIS-L-1013, using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation, and the conditions are that the sample yarn length is 20 cm and the tensile speed is 20 cm / min. The strength and elongation when the sample was stretched and fractured were measured and obtained. In addition, the strong elongation product was calculated from these values by the following formula. Considering the post-process and durability, the strong elongation product is preferably 20 or more, more preferably 22 or more.

＜熱水収縮率＞
ＪＩＳ−Ｌ−１０１３に準じ、熱水収縮率を求めた。
＜繊維の導電性評価（線抵抗値）＞
線抵抗値は、導電性複合繊維を１０ｃｍ採取し、その両端に導電性接着剤でアルミ箔を接着させ、ヒューレットパッカード製ハイレジスタンスメーター４３３９Ｂを用いて測定した。
＜サンプル生地の作製＞
導電性複合繊維を５６ｄｔｅｘ／２４ｆのポリエチレンテレフタレート繊維にカバリングしたカバリング糸を８ｍｍピッチで経糸に用い、その他の経糸及び緯糸は８４ｄｔｅｘ／３６ｆのポリエチレンテレフタレート繊維とし、タフタを作製し、７０℃の弱アルカリ性精練液にて精練し、１３０℃で染色し、乾燥した後１６０℃で熱セットしてサンプル生地とした。
＜シワの評価＞
サンプル生地を平坦な台の上に載せて光源を横方向から当てることにより目視でシワ不良の評価を行った。
シワのないものは○、軽度のシワがみられるものは△、強いシワがみられるものは×と評価した。

<Hot water shrinkage rate>
The hot water shrinkage rate was determined according to JIS-L-1013.
<Evaluation of fiber conductivity (line resistance value)>
The linear resistance value was measured by collecting 10 cm of a conductive composite fiber, adhering aluminum foil to both ends thereof with a conductive adhesive, and using a high resistance meter 4339B manufactured by Hewlett-Packard.
<Making sample fabric>
A covering yarn obtained by covering a conductive composite fiber with a polyethylene terephthalate fiber of 56 dtex / 24 f was used as a warp yarn at a pitch of 8 mm, and other warp yarns and weft yarns were made of a polyethylene terephthalate fiber of 84 dtex / 36 f to prepare a taffeta, which was weakly alkaline at 70 ° C. It was scoured with a scouring solution, dyed at 130 ° C., dried, and then heat-set at 160 ° C. to prepare a sample dough.
<Evaluation of wrinkles>
Wrinkle defects were visually evaluated by placing the sample fabric on a flat table and shining a light source from the side.
Those without wrinkles were evaluated as ○, those with mild wrinkles were evaluated as △, and those with strong wrinkles were evaluated as ×.

[Example 1]
A resin composition obtained by kneading 35% by mass of conductive carbon black with polyamide 6 is used as a conductive layer of a sheath, and polyamide MXD6 (MX nylon S-6011 manufactured by Mitsubishi Gas Chemicals Co., Ltd.) is used as a core non-conductive layer, and the conductive layer covers the entire fiber surface. Composite spinning was performed with a melt composite spinning machine using a mouthpiece for forming exposed core-sheath composite fibers. The number of holes in the base is 24, and the discharged composite fiber is divided into 8 threads, 1 thread is 3 filaments, and an undrawn thread is attached to a bobbin that rotates at 1500 m / min via an oiling guide and a godet roller. Winded up as. The undrawn yarn that has been wound is passed through a feed roller, a preheating roller at 90 ° C., and a heat setting roller at 150 ° C. in a twisting machine, and the elongation at break becomes about 30 to 80% between the preheating roller and the heat setting roller. As described above, the yarn was stretched with a difference in rotation speed and wound around a pan via a traveler to obtain a drawn yarn of a conductive composite fiber of 22dtex / 3f. The area ratio of the non-conductive layer / conductive layer in the cross section of the fiber was 83.3 / 16.7.
The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in the subsequent process. Further, a sample dough was prepared using the obtained conductive composite fiber. The obtained sample dough had no wrinkles and was of excellent quality.

[Example 2]
A drawn yarn of 22dtex / 3f conductive composite fiber was obtained under the same conditions as in Example 1 except that the conductive layer of the sheath was polyamide 12 and the conductive carbon black was kneaded in a resin composition of 35% by mass. The area ratio of the non-conductive layer / conductive layer in the cross section of the fiber was 83.3 / 16.7.
The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in the subsequent process. Further, a sample dough was prepared using the obtained conductive composite fiber. The obtained sample dough had no wrinkles and was of excellent quality.

[Example 3]
A resin composition obtained by kneading 35% by mass of conductive carbon black with polyamide 6 is used as a conductive layer for the core, and polyamide MXD6 (MX nylon S-6011 manufactured by Mitsubishi Gas Chemicals Co., Ltd.) is used as a non-conductive layer for the sheath, and the conductive layer covers the entire fiber surface. Composite spinning was performed with a melt composite spinning machine using a mouthpiece that was exposed at two points and formed a sandwich core-sheath type composite fiber sandwiched between non-conductive layers. The number of holes in the base is 24, and the discharged composite fiber is divided into 4 threads, 1 thread is 6 filaments, and an undrawn thread is attached to a bobbin that rotates at 1000 m / min via an oiling guide and a godet roller. Winded up as. The undrawn yarn that has been wound is passed through a feed roller, a preheating roller at 90 ° C., and a heat setting roller at 150 ° C. in a twisting machine, and the elongation at break becomes about 30 to 80% between the preheating roller and the heat setting roller. As described above, the yarn was stretched with a difference in rotation speed and wound around a pan via a traveler to obtain a drawn yarn of a conductive composite fiber of 22dtex / 6f. The area ratio of the non-conductive layer / conductive layer in the cross section of the fiber was 90.9 / 9.1.
The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in the subsequent process. Further, a sample dough was prepared using the obtained conductive fiber. The obtained sample dough had no wrinkles and was of excellent quality.

[Example 4]
A drawn yarn of 22dtex / 6f conductive composite fiber was obtained under the same conditions as in Example 3 except that the non-conductive layer was polyamide MXD8 (MX nylon LEXTER8000 manufactured by Mitsubishi Gas Chemical Company).
The obtained conductive composite fiber had excellent strength and elongation, and also had excellent passability in the subsequent process. Further, a sample dough was prepared using the obtained conductive fiber. The obtained sample dough had no wrinkles and was of excellent quality.

[Comparative Example 1]
A resin composition obtained by kneading 35% by mass of conductive carbon black with polyamide 6 is used as a conductive layer of a sheath, and polyamide 6 (ηr = 3.37) is used as a non-conductive layer of a core, and the conductive layer is exposed on the entire fiber surface. Composite spinning was performed with a melt composite spinning machine using a base for forming a mold composite fiber. The number of holes in the base is 24, and the discharged composite fiber is divided into 8 threads, 1 thread is 3 filaments, and an undrawn thread is attached to a bobbin that rotates at 1500 m / min via an oiling guide and a godet roller. Winded up as. The undrawn yarn that has been wound is passed through a feed roller, a preheating roller at 115 ° C., and a heat setting roller at 130 ° C. in a twisting machine, and the elongation at break becomes about 30 to 80% between the preheating roller and the heat setting roller. As described above, the yarn was stretched with a difference in rotation speed and wound around a pan via a traveler to obtain a drawn yarn of a conductive composite fiber of 22dtex / 3f. The area ratio of the non-conductive layer / conductive layer in the cross section of the fiber was 83.3 / 16.7.
The obtained conductive composite fiber has excellent strength and elongation. Using this, a sample dough was prepared. The obtained sample dough was wrinkled and wavy.

[Comparative Example 2]
A drawn yarn of 22dtex / 3f conductive composite fiber was obtained under the same conditions as in Comparative Example 1 except that the non-conductive layer was polyamide 6 (ηr = 2.58).
A sample dough was prepared using the obtained conductive composite fiber. The obtained sample dough had slight wrinkles.

[Comparative Example 3]
A drawn yarn of 22dtex / 3f conductive composite fiber was obtained under the same conditions as in Comparative Example 1 except that the non-conductive layer was polyamide 66 (ηr = 2.80).
A sample dough was prepared using the obtained conductive composite fiber. The obtained sample dough had slight wrinkles.

[Comparative Example 4]
A drawn yarn of 22dtex / 3f conductive composite fiber was obtained under the same conditions as in Comparative Example 1 except that the non-conductive layer was polyamide 66 (ηr = 3.80).
A sample dough was prepared using the obtained conductive composite fiber. The obtained sample dough had slight wrinkles.
Table 1 shows the composition of the conductive composite fibers obtained in Examples and Comparative Examples, and the physical properties of the yarn, and Table 2 shows the evaluation of wrinkles in the sample fabric prepared by using the conductive composite fibers.

From the results shown in Tables 1 and 2, the composite fibers obtained from the examples of the present invention were conductive composite fibers having excellent conductivity, strong elongation and dimensional stability. For this reason, it is excellent in durability and process passability, and is not wrinkled when mixed with polyester to form a cloth.

The conductive composite fiber of the present invention is excellent in high elongation and associated durability, process passability, conductivity, and dimensional stability during fabric processing. Therefore, it can be suitably used for dust-proof clothing for clean rooms, work clothing, and the like.

Claims (3)

A conductive composite fiber having a non-conductive layer and a conductive layer in the cross section of the fiber, the conductive layer is a polyamide containing 15% by mass or more and 45% by mass or less of conductive carbon black, and the non-conductive layer is a meta. A conductive composite fiber that is a polyamide obtained by polycondensation of xylene diamine and an aliphatic dicarboxylic acid. The conductive composite fiber according to claim 1, wherein the polyamide of the conductive layer is polyamide 6 or polyamide 12. The conductive composite fiber according to claim 1 or 2, wherein the area ratio of the non-conductive layer / conductive layer in the cross section of the fiber is 30/70 to 98/2.