JP7048468B2 - Unstretched conductive composite fiber and method for manufacturing BCF using it - Google Patents

Description

The present invention relates to an unstretched polyamide-based conductive composite fiber that exhibits excellent conductivity even after stretching, and a method for producing a BCF using the same.

Bulked continuous fiber (BCF) is a fiber obtained by spinning, stretching and crimping a resin such as polyamide, polypropylene, polyester or polylactic acid, and is used for carpets of automobiles, houses, vehicles, aircraft and the like. This carpet is required to have practical strength, light resistance, sag resistance, design and antistatic properties. As a method of imparting antistatic properties to a fabric such as a carpet, fibers containing an antistatic agent may be used, or the fabric itself may be subjected to antistatic processing. However, antistatic agents and antistatic processing exert their effects by the moisture of the outside air, and in a dry environment, the antistatic property of the carpet is impaired and unpleasant static electricity is generated. Therefore, as a method of obtaining high antistatic property under any environment, conductive fibers may be mixed into the carpet (Patent Document 1).

Japanese Unexamined Patent Publication No. 7-2589220

As a method of mixing conductive fibers into carpet, there is a method of mixing conductive fibers containing carbon black during BCF production. BCF is usually manufactured by melting the resin, extruding it from a nozzle with a large number of holes, passing it through multiple rollers, continuously stretching it, performing bulk processing with an air jet, and winding it with a winder. Will be done. In this step, the conductive yarn wound on the bobbin or the like is unwound on the yarn extruded from the nozzle and before being drawn, and the yarn is mixed through a guide or the like. Here, the mixed conductive yarn must not only not break with respect to stretching, but also have a certain level of conductivity even after stretching and bulk processing. Further, if the black streaks peculiar to carbon black become conspicuous when the conductive yarn is mixed with the carpet, the design of the carpet is significantly impaired.
It is an object of the present invention to provide a conductive yarn which has sufficient conductivity even when mixed and stretched during BCF production and whose black streaks are inconspicuous when used for carpets.

That is, the present invention has a conductive layer made of a polyamide containing 20% by mass or more and 45% by mass or less of conductive carbon black, and a protective layer made of a polyamide containing 5% by mass or more of a concealing inorganic pigment. The elongation at break is 200 to 600%, the linear resistance value is 1.0E + 05 to 9.9E + 07Ω / cm, and the ratio of the exposed peripheral length of the conductive layer to the total peripheral length is less than 8%, unstretched conductivity. The gist is composite fiber.
The unstretched conductive composite fiber is preferably supplied to the drawing step when producing BCF.
The unstretched conductive composite fiber preferably has three or more convex portions on the outer periphery of the protective layer in the cross section of the fiber.
The present invention is also a method for producing BCF by mixing non-conductive fibers and conductive fibers, the first step of melt-spinning non-conductive fibers, unstretched non-stretched obtained by melt-spinning. The second step of mixing and stretching the conductive fibers and the unstretched conductive fibers, the third step of bulk processing the mixed drawn yarn by fluid injection, and the fourth step of winding up the obtained bulky processed yarn. It is also a method for producing BCF including.

According to the present invention, it is possible to provide a conductive yarn which has sufficient conductivity even when mixed and stretched during BCF production and whose black streaks are inconspicuous when used for a carpet.

It is explanatory drawing which shows the example of the manufacturing method of BCF in this invention.

Hereinafter, the present invention will be described in detail.
The present invention is an unstretched conductive composite fiber composed of a conductive layer and a protective layer.

In the present invention, the thermoplastic resin serving as the base polymer constituting the conductive layer is polyamide.
Examples of these polyamides include polyamide 6, polyamide 66, polyamide 12, polyamide 11, polyamide 610, and a copolymer containing them as a main component, and polyamide 6, polyamide 66, and polyamide 12 are preferable.

The conductive layer of the unstretched conductive composite fiber of the present invention is a polyamide containing 20% by mass or more and 45% by mass or less of conductive carbon black.

In the conductive composite fiber of the present invention, the conductive layer contains 20% 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 is lost during spinning and the spinning property tends to be deteriorated. Above all, the content of carbon black is preferably 25% 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, acetylene black, channel black, and the like, and the carbon black having excellent conductivity is not particularly limited.

In the present invention, the thermoplastic resin constituting the protective layer is polyamide.
The protective layer is usually a non-conductive layer that does not contain carbon black as a conductive material.
Examples of the polyamide used as the protective layer in the present invention include polyamides such as polyamide 6, polyamide 66, polyamide 12, polyamide 11, polyamide 610, and polyamide 612, and copolymers thereof, which can be melt-spun. If there is, the present invention is not particularly limited, and polyamide 6 and polyamide 66 are preferable.

The protective layer of the unstretched conductive composite fiber of the present invention contains a concealing inorganic pigment. This concealing inorganic pigment hides the carbon black coloring of the conductive part.

The content of the concealing inorganic pigment is 5% by mass or more, more preferably 7% by mass or more, based on the polyamide of the protective layer. If the content of the concealing inorganic pigment is too high, the molten spinning nozzle becomes more dirty during the production of the conductive composite fiber, and the yield is lowered, the physical properties of the obtained conductive composite fiber are lowered, and the guide of the spinning device is used. The upper limit of the content of the concealing inorganic pigment is preferably about 15% by mass, because the content of the hiding inorganic pigment is deteriorated by abrasion.
In the above range, by containing a concealing inorganic pigment in the protective layer, the coloring of carbon black is effectively concealed without causing deterioration of yarn-making property and thread physical characteristics, and black streaks peculiar to carbon black-containing fibers are formed. It is inconspicuous and has good design.

Examples of such a hiding inorganic pigment preferably include whitening agents such as titanium oxide, barium sulfate, calcium oxide, and zinc oxide, and titanium oxide is particularly preferable.

The concealing inorganic pigment in the present invention may be appropriately selected in consideration of cost, whiteness, the influence on the strength and elongation of the fiber, and the wear resistance to the guide of the fiber processing machine.

The method of incorporating these concealing inorganic pigments in the protective layer is not particularly limited, but may be kneaded with polyamide in advance and melt-spun as a compound, or the resin kneaded product may be pelletized once. You may continuously perform kneading and melt spinning without kneading. Further, a high-concentration masterbatch containing 30% by mass or more of the concealing inorganic pigment may be prepared in advance and diluted with a dry blend at the time of melt spinning to adjust the concentration.

The breaking elongation of the unstretched conductive composite fiber of the present invention is 200 to 600%. If the elongation at break is less than 200%, the fibers are mixed during BCF production, and yarn breakage and a decrease in conductivity (significant increase in linear resistance value) occur during drawing and bulk processing. In addition, when the elongation at break exceeds 600%, the reason is not clear, but when BCF is used, only the conductive composite fiber slackens from the BCF and becomes a floating form, and the weaving property when making a carpet, It adversely affects the durability of design and conductivity. Above all, 250 to 550% is preferable.

The breaking strength of the unstretched conductive composite fiber of the present invention is preferably 0.4 cN / dtex or more, and more preferably 0.6 cN / dtex or more. Although there is no particular upper limit, the upper limit is preferably about 2.5 cN / dtex in consideration of the balance between the undrawn yarn and the elongation at break. Within this range, stability of blending, stretching, and bulk processing during silk reeling and BCF production can be obtained, which is preferable.

The total fineness of the unstretched conductive composite fiber of the present invention is preferably 15 to 80 dtex, more preferably 20 to 60 dtex. This range is preferable because sufficient whiteness, designability when used as a carpet, conductivity, and stability of fiber blending, drawing, and bulk processing during silk reeling and BCF production can be obtained.

The number of filaments of the unstretched conductive composite fiber of the present invention is not particularly limited, but is preferably 1 to 8f, more preferably 1 to 6f, and is determined in consideration of the whiteness and the breaking strength of the single yarn. do.

The linear resistance value of the unstretched conductive composite fiber of the present invention is 1.0E + 05 to 9.9E + 07Ω / cm. Within this range, sufficient conductivity can be obtained for blending, stretching, and bulk processing stability during silk reeling and BCF manufacturing, and sufficient conductivity can be obtained for BCF, and good antistatic properties for carpets. Is shown.
The package (rolled form) of the unstretched conductive composite fiber of the present invention is wound around a bobbin or a pan, and the end face of the package has a taper angle of less than 90 ° even at a square end having a taper angle of 90 °. It may be a tapered end. In addition, a package may have a square end up to a certain inner bobbin diameter and a tapered end from that position to the outer layer, which are easy to handle, transport, transport efficiency and ease, and when blended into BCF. It may be determined in consideration of the stability of feeding out the conductive composite fiber from the package.

In the present invention, the fiber cross section refers to a plane perpendicular to the fiber axis longitudinal direction.
In the unstretched conductive composite fiber of the present invention, it is preferable that the conductive layer and the protective layer are continuous in the fiber longitudinal direction.

The area ratio of the protective layer / the conductive layer in the fiber cross section of the conductive composite fiber of the present invention is preferably 100/1 to 3/1, more preferably 50/1 to 5/1. If the area ratio of the protective layer is too high, the whiteness will be high, but sufficient conductivity may not be obtained. Further, if the area ratio of the protective layer is too low, not only a sufficient whiteness cannot be obtained, but also the breaking strength and the breaking elongation are lowered, and there is a possibility that yarn breakage occurs frequently in the drawing step at the time of BCF blending.
The cross-sectional shape of the fiber cross section of the conductive composite fiber of the present invention is a non-exposed type in which the conductive layer is completely wrapped in a protective layer, and the conductive layer is exposed to a part of the fiber surface or the entire fiber surface. It can be of any type. However, in order to have sufficient whiteness when made into a fiber, it is preferable that the exposed length of the conductive layer on the fiber surface in the fiber cross section is short, and the conductive layer with respect to the entire circumference of the fiber cross section of the conductive composite fiber. The ratio of the exposed peripheral length is preferably less than 8%, more preferably 0%, that is, the conductive layer is unexposed.
The cross section of the fiber is not particularly limited, such as a round cross section, a triangular cross section, and a multi-leaf cross section, but a multi-leaf cross section is preferable in order to increase the whiteness of the fiber due to diffused reflection.
A particularly preferable cross-sectional shape is one having three or more convex portions on the outer periphery of the protective layer in the cross section of the fiber. As a result, light is easily reflected diffusely, and excellent whiteness is easily obtained.

The L * value of the unstretched conductive composite fiber of the present invention measured by the method described later is preferably 65 or more, more preferably 70 or more. Within this range, black streaks of conductive fibers are not noticeable when used as a carpet.

Such an unstretched conductive composite fiber of the present invention is mixed with threads discharged from a nozzle when BCF is manufactured, and is not broken and maintains conductivity against stretching and bulky processing. Therefore, when a BCF carpet is used, good antistatic properties can be obtained without conspicuous black streaks.

An example of a suitable manufacturing method of the unstretched conductive composite fiber of this invention is shown.
The above-mentioned conductive carbon black and the above-mentioned polyamide are prepared and kneaded to produce a resin composition. The obtained resin composition is used as a conductive layer, and a polyamide containing 5% by mass or more of a hiding material is used as a protective layer, and melted by using a composite base ejected in a state where the conductive layer and the protective layer are composited in the cross section of the fiber. Composite spinning is performed to produce conductive composite fibers.
At the time of melt spinning, the spinning temperature is preferably the melting point of the polyamide used as a raw material + 10 ° C to 80 ° C, and the spinning speed is preferably about 400 to 1800 m / min. The shape is also good. Further, polyamide has high water absorption and hygroscopicity among synthetic fibers, and its characteristics become remarkable especially when it is unstretched. Therefore, the oil agent to be applied and the winding environment temperature / humidity are appropriately adjusted.
FIG. 1 shows an example of a method for producing BCF. The non-conductive unstretched fibers discharged from the melt spinning apparatus 1 and the unstretched conductive composite fibers 2 of the present invention are aligned and mixed via a guide 3, and the oil is applied by the oiling roller 4, and the first It is supplied to the goded roller 5 and stretched between the first goded roller 5 and the second goded roller 6. Next, the obtained drawn yarn is bulk-processed by fluid injection with the bulk-bulging processing device 7, and is wound around a winder 8 to obtain BCF 9. Further, a roller may be appropriately installed after the second godet roller 6 for the purpose of stabilizing the yarn running, its direction, and the winding tension, and for the purpose of multi-stage stretching or relaxation.
The mixing ratio of the unstretched non-conductive fiber and the unstretched conductive composite fiber is the mass ratio at the time of becoming BCF, and the unstretched conductive composite fiber may be mixed by about 0.2 to 5% by mass with respect to the BCF. preferable.
To give a suitable example of the drawing conditions of the first Godded Roller 5 and the second Godded Roller 6, for example, the temperature of the first Godded Roller 5 may be room temperature, but the drawing stability and the conductive composite fiber may be used. In order to maintain the conductivity of 40 ° C. or higher, the temperature of the second goded roller 6 is higher than the temperature of the first godded roller, preferably 110 ° C. or higher, and more preferably 130 ° C. or higher. The draw ratio is 2.0 to 4.5 times, and is determined in consideration of the strong elongation of BCF and the crimping characteristics.
Further, the bulky processing method is not particularly limited, but for example, fluid injection processing (air jet) is preferably mentioned.
Using the BCF thus obtained, tufting is performed through various known processing steps, and the carpet is refined, dyed, has excellent antistatic properties, and has black streaks inconspicuous and has good design. Obtainable.

Hereinafter, the present invention will be specifically described 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.

<Breaking strength, breaking elongation>
The breaking strength and breaking elongation of the conductive composite fiber are in accordance with JIS L 1013, and a sample is used under the conditions of a sample yarn length of 5 cm and a tensile speed of 10 cm / min using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation. Was obtained by measuring the strength and elongation at the time of elongation fracture.
<Evaluation of fiber conductivity (line resistance value)>
For the linear resistance value, 10 cm of the conductive composite fiber was collected, aluminum foil was adhered to both ends thereof with a conductive adhesive, and the resistance value at a length of 10 cm was measured using a high resistance meter 4339B manufactured by Agilent. The measured value was divided by 10 cm to obtain a linear resistance value (Ω / cm).
<Whiteness evaluation by nuance volume>
Unstretched conductive fibers are wrapped around a blackboard with a basis weight of 1.2 g / cm ² or more so that the blackboard does not show through, and the fibers are not stretched. The L ^* value was measured using. When the L ^* value is 65 or more, the black streaks of the conductive composite fiber are not conspicuous when the BCF is used and when the carpet is used.

[Example 1]
The resin composition obtained by kneading the polyamide 6 with 35% by mass of conductive carbon black is used as the core conductive layer, and the polyamide 6 containing 9.7% by mass of anatase-type titanium oxide is used as the protective layer of the sheath, and the conductive layer is completely formed as the protective layer. The protective layer was subjected to composite spinning with a melt composite spinning machine using a base having a cross-shaped cross section having four protrusions (convex portions). The gear pump was adjusted so that the area ratio of the protective layer and the conductive layer in the fiber cross section was 10: 1, the composite fiber discharged from the 8-hole nozzle was divided into eight, oiled, and 680 m as a 35 dtex monofilament. Unstretched composite conductive fibers were wound around eight bobbins rotating at / min.

[Example 2]
The resin composition obtained by kneading the polyamide 6 with 35% by mass of conductive carbon black is used as the core conductive layer, and the polyamide 6 containing 9.7% by mass of anatase-type titanium oxide is used as the protective layer of the sheath, and the conductive layer is completely formed as the protective layer. The protective layer was subjected to composite spinning with a melt composite spinning machine using a base having a cross-shaped cross section having four protrusions (convex portions). The gear pump was adjusted so that the area ratio of the protective layer and the conductive layer in the fiber cross section was 30: 1, the composite fiber discharged from the 8-hole nozzle was divided into eight, oiled, and 680 m as a 35 dtex monofilament. Unstretched composite conductive fibers were wound around eight bobbins rotating at / min.

[Example 3]
A resin composition obtained by kneading 35% by mass of conductive carbon black with polyamide 6 is used as a conductive layer of the core, and polyamide 6 containing 9.7% by mass of anatase-type titanium oxide is used as a protective layer of a sheath, and a conductive layer is formed on the fiber surface. The protective layer was subjected to composite spinning with a melt composite spinning machine using a base having a cross-shaped cross section having four protrusions (convex portions). The gear pump was adjusted so that the area ratio of the protective layer and the conductive layer in the fiber cross section was 30: 1, the composite fiber discharged from the 8-hole nozzle was divided into eight, oiled, and 680 m as a 35 dtex monofilament. Unstretched composite conductive fibers were wound around eight bobbins rotating at / min. The conductive layer was exposed in one recess in the cross section of the fiber, and the ratio of the exposed peripheral length of the conductive layer to the total peripheral length was 5%.

[Example 4]
A resin composition in which 35% by mass of conductive carbon black is kneaded with polyamide 6 is used as a core conductive layer, and a polyamide 6 containing 50% by mass of rutile-type titanium oxide and a polyamide containing 0.3% by mass of anatase-type titanium oxide are dried. The protective layer is made by blending and adjusting the blend ratio so that the total content of titanium oxide in the protective layer is 6.2% by mass. The conductive layer is completely wrapped in the protective layer, and the protective layer has four protrusions (4 protrusions (). Composite spinning was performed with a melt composite spinning machine using a base having a cross-shaped cross section (convex portion). The gear pump was adjusted so that the area ratio of the protective layer and the conductive layer in the fiber cross section was 30: 1, the composite fiber discharged from the 8-hole nozzle was divided into eight, oiled, and 680 m as a 35 dtex monofilament. Unstretched composite conductive fibers were wound around eight bobbins rotating at / min.

[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 the core, and polyamide 6 containing 9.7% by mass of anatase-type titanium oxide is used as a protective layer of a sheath, and a conductive layer is formed on the fiber surface. The protective layer was partially exposed, and composite spinning was performed with a melt composite spinning machine using a base having a cross-shaped cross section having four protrusions. The gear pump was adjusted so that the area ratio of the protective layer and the conductive layer in the fiber cross section was 30: 1, the composite fiber discharged from the 8-hole nozzle was divided into eight, oiled, and 680 m as a 35 dtex monofilament. Unstretched composite conductive fibers were wound around eight bobbins rotating at / min. The conductive layer was exposed in one recess in the cross section of the fiber, and the ratio of the exposed peripheral length of the conductive layer to the total peripheral length was 16%.

[Comparative Example 2]
The resin composition obtained by kneading the polyamide 6 with 35% by mass of conductive carbon black is used as the core conductive layer, and the polyamide 6 containing 1.6% by mass of anatase-type titanium oxide is used as the protective layer of the sheath, and the conductive layer is completely formed as the protective layer. The protective layer was subjected to composite spinning with a melt composite spinning machine using a base having a cross-shaped cross section having four protrusions. The gear pump was adjusted so that the area ratio of the protective layer and the conductive layer in the fiber cross section was 30: 1, the composite fiber discharged from the 8-hole nozzle was divided into eight, oiled, and 680 m as a 35 dtex monofilament. Unstretched composite conductive fibers were wound around eight bobbins rotating at / min.

The unstretched conductive composite fiber packages obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were set on the krill, and unstretched from the krill on the threads of the 96-filament polyamide 6 discharged from the melt spinning apparatus. The conductive composite fibers are mixed via a guide and continuously stretched between the first godet rollers at 50 ° C. rotating at 900 m / min and the second godet rollers at 160 ° C. rotating at 2800 m / min. After further bulk processing with an air jet at 160 ° C., the fibers were wound up with a winder. The obtained BCF was 1560 dtex / 97f, and one filament of the stretched conductive composite fiber was contained. At this time, the feeding (unwinding property), stretching and processing of the yarn from all the obtained unstretched conductive composite fiber packages were stable. In addition, the carpet manufactured by using two BCFs mixed with these conductive composite fibers per 2.54 cm has a human body band voltage of 3.0 kV (absolute value) or less according to the human body band voltage measurement method, which is an excellent control. Shown electrical.
The BCF obtained using Examples 1 to 4 was excellent in conductivity, and the streaks were not conspicuous as compared with the BCF containing no conductive composite fiber. The BCF obtained by using Comparative Examples 1 and 2 had black or gray streaks conspicuous as compared with the BCF containing no conductive composite fiber.
<Reference example 1>
A package of 33 dtex / 3f stretched conductive composite fiber (breaking strength 2.9 cN / dtex, breaking elongation 65%, linear resistance value 3.5E + 07Ω / cm) is set in the krill, and 96 filaments discharged from the melt spinning device. 1. Although it was continuously stretched between the second Godet rollers, the conductive composite fibers were repeatedly broken between the rollers, and BCF could not be stably obtained.
<Reference example 2>
A 96-filament polyamide 6 yarn discharged from a melt spinning apparatus is continuously rotated between a first godet roller at 50 ° C. rotating at 900 m / min and a second godet roller at 160 ° C. rotating at 2800 m / min. Stretched conductive composite fiber of 33 dtex / 3f stretched conductive composite fiber (break strength 2.9 cN / dtex, breaking elongation 65%, linear resistance value 3.5E + 07 Ω / cm) set in krill after stretching. The fibers were mixed, bulky processed by a fluid injection at 160 ° C., and then wound up with a winder. The feeding from the package was not stable, and the yarn breakage and the shape of the package were deformed, so that the yield of the obtained BCF was lowered.

1 Melt spinning device 2 Unstretched conductive fiber 3 Guide 4 Oil agent application roller 5 1st Godet roller 6 2nd Godet roller 7 Bulk processing device 8 Winder 9 BCF

Claims (4)

A fiber supplied to the drawing step in the production of BCF, which contains a conductive layer made of polyamide containing 20% by mass or more and 45% by mass or less of conductive carbon black, and 5% by mass or more of a concealing inorganic pigment. It has a protective layer made of polyamide, has three or more convex portions on the outer periphery of the protective layer in the cross section of the fiber, has a breaking elongation of 200 to 600%, and has a linear resistance value of 1.0E + 05 to 9. It is .9E + 07Ω / cm, the ratio of the exposed peripheral length of the conductive layer to the total peripheral length of the fiber cross section is less than 8%, and the grain size is 1.2 g / cm ² or more so that the blackboard does not show through, without stretching without gaps. An unstretched conductive composite fiber having an L ^* value of 65 or more when wrapped around a blackboard . The unstretched conductive composite fiber according to claim 1, wherein the ratio of the exposed peripheral length of the conductive layer to the total peripheral length of the fiber cross section is 0%. The unstretched conductive composite fiber according to claim 1 or 2, which is a protective layer made of a polyamide containing 7% by mass or more of a concealing inorganic pigment. A method for producing BCF by mixing non-conductive fibers and conductive fibers, wherein the first step of melt-spinning non-conductive fibers is unstretched non-conductive fibers obtained by melt-spinning. Item 2 The second step of mixing and drawing unstretched conductive fibers according to any one of Items 1 to 3, the third step of bulk processing the mixed drawn yarn by fluid injection, and the obtained bulky processed yarn. A method for producing BCF, which comprises a fourth step of winding.

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