CN101437992A - Conductive composite fiber and method for producing same - Google Patents

Abstract

Disclosed is a conductive composite fiber with an elongation (DE) of 100-350%. The conductive composite fiber is made by combining a conductive layer (A) containing 60-80% by weight of thermoplastic resin and 20-40% by weight of conductive particles and The protective layer composed of 50-95% by weight of polyethylene terephthalate and 5-50% by weight of polyethylene 2,6-naphthalene dicarboxylate is prepared by compounding. This conductive composite fiber has excellent electrical conductivity. During the transportation or storage process of the conductive composite fiber, the fiber properties such as elongation or shrinkage in boiling water change little with time, and at the same time have a certain elongation.

Description

Conductive composite fiber and its preparation method

technical field

[0001]

The present invention relates to a conductive composite fiber, in particular to a conductive composite fiber prepared by compounding a conductive layer containing a thermoplastic resin and conductive particles and a polyester protective layer. The invention also relates to a suitable method for preparing such conductive composite fibers.

technical background

[0002]

Hitherto, various conductive fibers have been known, specifically, conductive composite fibers having a conductive layer composed of a thermoplastic resin composition containing conductive particles such as carbon black and a protective layer composed of a thermoplastic resin not containing conductive particles has been widely used. This is obtained by co-spinning a thermoplastic resin composition containing conductive particles and a thermoplastic resin not containing conductive particles, wherein the conductive layer is continuously arranged on the fiber surface or inside along the fiber longitudinal direction. Such conductive composite fibers are disclosed in, for example, Patent Documents 1-4.

[0003]

In order to obtain sufficient conductive performance by a conductive layer composed of a thermoplastic resin composition containing conductive particles, it is necessary to incorporate a large amount of conductive particles into the thermoplastic resin composition. However, there is a problem that spinnability or stretchability is severely deteriorated when a large amount of conductive particles is mixed. If stretched by force, the conductive layer inside the fiber breaks. Or, even if it does not break, the structure of the conductive carbon black may be destroyed or further the conductive layer may be easily broken due to a slight external force applied to the conductive fiber in actual use, with the result that conductive properties may be lost. Therefore, in the process of preparing conductive composite fibers, the fibers are not sufficiently drawn in many cases, and fiber properties such as elongation and shrinkage in boiling water may change with time. Specifically, when an electroconductive conjugate fiber required to have elongation or boiling water shrinkage above a certain level is produced for use as a blended yarn or the like, drastic changes in physical properties over time become a more significant problem.

[0004]

Patent Document 5 describes a high-shrinkage polyester fiber composed of a polyester resin composition obtained by mixing polyethylene terephthalate and polyethylene naphthalate. It is described that the high-shrinkage polyester fiber has a high shrinkage rate and a high shrinkage stress and is excellent in storage stability at a high temperature of not lower than 70°C. However, Patent Document 5 only describes high-shrinkage fibers consisting only of the above-mentioned polyester resin composition. It neither describes fibers composed of a resin composition containing a large amount of conductive particles nor composite fibers.

[0005]

Patent Document 1: JP 57-29611 A

Patent Document 2: JP 58-132119 A

Patent Document 3: JP 9-279416 A

Patent Document 4: JP 2003-278031 A

Patent Document 5: JP 2001-288618 A

Contents of the invention

The problem to be solved by the present invention

[0006]

The present invention is intended to solve the above problems, and one object is to provide conductive composite fibers having excellent electrical conductivity that can be maintained for a long period of time and which exhibit small dynamic properties such as elongation over time during transportation or storage Or the boiling water shrinkage changes, and at the same time has a certain elongation. Furthermore, it is an object to provide a method for preparing such conductive composite fibers.

way of solving the problem

[0007]

The above problems can be solved by providing a conductive composite fiber by combining a conductive layer (A) containing 60-80% by weight of a thermoplastic resin and 20-40% by weight of conductive particles and a layer containing 50-95% by weight of polyparaphenylene Prepared by compounding a protective layer (B) of ethylene glycol diformate and 5-50% by weight polyethylene 2,6-naphthalene dicarboxylate, wherein the elongation (DE) of the fibers is 100-350% .

[0008]

At this time, it is preferable that the thermoplastic resin constituting the conductive layer (A) is polybutylene terephthalate or polyamide. It is also preferred that the weight ratio (A/B) of the fibrous conductive layer (A) to the protective layer (B) is 5/95-50/50. It is also preferred that the boiling water shrinkage ratio (Wsr) is 20-60%. It is also preferable that the elongation (DE ₆₀ ) at 60 days after spinning is not more than 1.3 times the elongation (DE ₁ ) at 1 day after spinning when the fiber is stored at 60° C. and 80% RH, and the spinning The boiling water shrinkage (Wsr ₆₀ ) at 60 days after spinning is not less than 0.3 times the boiling water shrinkage (Wsr ₁ ) at 1 day after spinning, and the boiling water shrinkage at 60 days after spinning (Wsr ₆₀ ) is not less than 10%. A carpet in which fibers obtained by drawing such conductive composite fibers are used is a preferred embodiment of the present invention.

[0009]

The above problems can also be solved by providing a method for preparing conductive composite fibers, the method comprising mixing a resin composition (a) comprising 60-80% by weight of a thermoplastic resin and 20-40% by weight of conductive particles and a resin composition (a) comprising 50-95% by weight Resin composition (b) composite spinning of polyethylene terephthalate and 5-50% by weight polyethylene 2,6-naphthalene dicarboxylate, wherein molten resin composition (a) and molten resin Compositions (b) are merged, melted and sprayed through a composite spinneret, and then wound at a speed of 1500-3000 m/min. At this time, the following steps (1)-(5) are preferably carried out in sequence, and (2) and (3) are carried out before the ejected filament contacts the guide roller or the wire guide for the first time:

(1) Merge the molten resin polymer (a) and the molten resin composition (b) and melt and eject them through a composite spinneret,

(2) Temporarily cooling the ejected molten resin composition to a temperature lower than the glass transition point,

(3) subsequently transporting it through a heating device to subject it to thermal stretching,

(4) oil it afterwards, and

(5) Coil it at a speed of 1500-3000 m/min.

Effect of the invention

The conductive composite fiber of the present invention has excellent electrical conductivity maintained for a long time and exhibits small dynamic properties such as changes in elongation or boiling water shrinkage over time during transportation or storage while having a certain elongation. Therefore, the physical properties of the fiber are stable in long-distance transportation such as international transportation or long-term storage. The conductive composite fiber of the present invention exhibits good processability in the production process for subsequent processing such as blending, twisting, weaving, knitting, etc., and uniform products can be obtained therefrom. According to the preparation method of the present invention, such conductive composite fibers can be easily obtained.

Brief description of the drawings

[0011]

[ Fig. 1 ] A graph showing the results obtained by measuring changes in elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity with time for the conjugated fibers obtained in Example 1.

[ Fig. 2 ] A graph showing the results obtained by measuring changes in elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity with time for the conjugated fibers obtained in Example 2.

[ Fig. 3 ] A graph showing the results obtained by measuring changes in elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity with time for the conjugated fibers obtained in Example 3.

[ Fig. 4 ] A graph showing the results obtained by measuring changes in elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity with time for the conjugated fibers obtained in Example 4.

[ Fig. 5 ] A graph showing the results obtained by measuring changes in elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity with time for the conjugate fiber obtained in Comparative Example 1.

Best Mode for Carrying Out the Invention

[0012]

The conductive composite fiber of the present invention is obtained by combining a conductive layer (A) comprising 60-80% by weight of thermoplastic resin and 20-40% by weight of conductive particles and comprising 50-95% by weight of polyethylene terephthalate and 5-50% by weight. % by weight A fiber prepared by compounding a protective layer (B) of polyethylene 2,6-naphthalate.

[0013]

The thermoplastic resin contained in the conductive layer (A) may be any fiber-forming thermoplastic resin, and its kind is not particularly limited. Typically, thermoplastic polyesters or thermoplastic polyamides are suitable. From the standpoint of practical durability, it is preferable that the melting point of the resin constituting the conductive layer (A) is 200° C. or higher. The melting point is more preferably 210°C or higher and 250°C or lower.

[0014]

Examples of thermoplastic polyesters used for the conductive layer (A) include the use of dicarboxylic acid components such as aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4' - biphenyl dicarboxylic acid, sodium 5-sulfonate isophthalate, and aliphatic dicarboxylic acids such as azelaic acid, sebacic acid; and dihydric alcohol components, such as aliphatic dihydric alcohols, such as ethylene glycol, Diethylene glycol, propylene glycol, 1,4-butanediol, polyethylene glycol, polytetramethylene glycol, aromatic diols such as the ethylene oxide adducts of bissulfone A or bissulfone S, and alicyclic Fiber-forming polyesters prepared from dihydric alcohols such as cyclohexanediol. Specifically, polyesters having 80 mol% or more, especially 90 mol% or more of ethylene terephthalate units or butylene terephthalate units, which are general-purpose polyesters, are preferred.

[0015]

Specifically, polybutylene terephthalate, that is, polyester having 80 mol% or more of butylene terephthalate units, is preferable because conductive particles are easily kneaded therein and it is easy to crystallize, so it can be Obtain high electrical conductivity. Although polyethylene terephthalate can also be used, the addition of a large amount of conductive particles leads to deterioration of spinnability at the time of melt spinning. Copolymerized polyethylene terephthalate can be used to improve spinnability. However, the use of copolymerized polyethylene terephthalate generally results in deterioration of crystallinity, which leads to a decrease in electrical conductivity. From the above facts, polybutylene terephthalate, which is a polyester that easily forms crystals, is particularly excellent. Polyethylene 2,6-naphthalate may be added to polybutylene terephthalate.

[0016]

Polyethylene adipate (nylon 66), polycaprolactam (nylon 6) or copolymers thereof are suitable as thermoplastic polyamides for the conductive layer (A). This thermoplastic polyamide is suitable because it is as easy to knead a large amount of conductive particles into it as polybutylene terephthalate.

[0017]

The conductive particles contained in the conductive layer (A) are not particularly limited as long as they are particles having conductivity. For example, conductive carbon black, conductive metal oxide particles, metal particles, and the like can be used. Specifically, conductive carbon black is preferably used in terms of a balance between conductive performance and cost. The particle diameter of the conductive particles is not particularly limited as long as it is a size that can be spun, but it is preferable that the average particle diameter is 0.01 to 1 μm.

[0018]

The conductive carbon black used in the present invention preferably has an intrinsic resistivity of 10 ⁻³ to 10 ³ Ω·cm. When carbon black is fully dispersed as particles, the electrical conductivity is generally poor, and when the carbon black forms a chain structure called "structure", the electrical conductivity is improved, and this carbon black is called "conductive carbon black". Thus, in imparting electrical conductivity to polymers by using carbon black, it is important to disperse this carbon black without destroying the structure. Therefore, in many cases, sufficient drawing is not possible, and fibers with insufficient dimensional stability will be formed.

[0019]

Also, unlike carbon black, conductive metal oxide particles are not black. Therefore, they can impart electrical conductivity to white fibers and can be used in designs. The conductive metal oxide particles used in the present invention refer to fine particles of white or colorless metal oxides, or fine particles each containing inorganic fine particles as a core, the surface of which is covered with metal oxides. Most metal oxides are semiconductors, which are almost insulators and not sufficiently conductive. However, as a conductivity enhancer (dopant) of metal oxides, antimony oxide is used for tin oxide, aluminum and potassium are used for zinc oxide, and the like are known. For example, while the specific resistance of tin oxide having an average particle diameter of 0.1 μm is about 10 ³ Ω·cm, the specific resistance of a solid solution of antimony oxide and tin oxide is 1-10 Ω·cm, so that conductivity is improved. Considering comprehensive performance, the proportion of antimony oxide in the solid solution must be adjusted to 0.01-0.10 (weight ratio). If the coverage amount of antimony oxide is small, the conductivity will become insufficient. On the other hand, if the amount is large, the color will deviate from the desired white. As the conductive particles used in the present invention, the above-coated zinc oxide and tin oxide are preferable because they are excellent in conductivity, whiteness, etc., and metal oxides other than the above may also be used.

[0020]

In the present invention, one kind of conductive particles or a mixture of two or more kinds of conductive particles can be used. At this time, conductive carbon black and conductive metal oxide particles may be used in combination. In addition, metal particles and the like may be used. Various additives may be mixed unless the effect of the present invention is affected.

[0021]

The conductive layer (A) of the present invention is a layer composed of 60-80% by weight of thermoplastic resin and 20-40% by weight of conductive particles. When the content of the conductive particles is less than 20% by weight, the conductivity may become insufficient. The conductive particle content is preferably 23% by weight or more, and the thermoplastic resin content is 77% by weight or less. On the other hand, when the conductive particle content exceeds 40% by weight, spinnability and stretchability may deteriorate. The content of the conductive particles is preferably 33% by weight or less, and the content of the thermoplastic resin is 67% by weight or more.

[0022]

The protective layer (B) of the present invention is a layer composed of 50-95% by weight of polyethylene terephthalate and 5-50% by weight of polyethylene-2,6-naphthalate. When the protective layer (B) is a layer which contains polyethylene terephthalate as a main component and polyethylene 2,6-naphthalate is mixed therein, it is possible to control performance changes. In the case of the conductive composite fiber, since the resin composition used for its conductive layer contains a large amount of conductive particles, the conductive layer does not contribute much to the dynamic properties of the composite fiber. Therefore, the dynamic performance of its protective layer is particularly important.

[0023]

The polyethylene terephthalate used for the protective layer (B) is a polyester having 80 mol% or more, preferably 90 mol% or more of ethylene terephthalate units. The third component can be copolymerized unless it is detrimental to the object of the present invention. Examples of preferably used copolymerizable components include acid components such as isophthalic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, sodium isophthalic acid sulfonate and isophthalic acid sulfonic acid Tetrabutylphosphine; and glycol components such as diethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol and 2, 2-bis[4-(2-hydroxyethoxy)phenyl]propane.

[0029]

The polyethylene 2,6-naphthalene dicarboxylate used for the protective layer (B) is a polyester containing 80 mol% or more, preferably 90 mol% or more 2,6-naphthalene dicarboxylate units. The third component can be copolymerized unless it is detrimental to the object of the present invention. As preferably used copolymerizable components, terephthalic acid or those mentioned in the description of polyethylene terephthalate can be used.

[0025]

Considering spinnability and knitting/weaving properties, it is preferable that inorganic fine particles having an average particle diameter of 0.01-1 μm are contained in the polyethylene terephthalate used for the protective layer (B) in a proportion of 0.05-10% by weight or polyethylene 2,6-naphthalate. That is, when the inorganic fine particle content is less than 0.05% by weight, the resulting conductive fiber has loops, fluff, unevenness in fineness, and the like. When the content exceeds 10% by weight, the processability in the production process is poor, which may cause fiber breakage. It is more preferable to contain 0.2 to 5% by weight of inorganic fine particles. The method of adding the inorganic fine particles is not particularly limited. It is only required to add and mix the inorganic fine particles so that the particles are uniformly mixed in the polyester at any time between polyester polymerization and just before melt spinning. A representative example of such inorganic particles is titanium oxide.

[0026]

The protective layer (B) is a layer composed of 50-95% by weight of polyethylene terephthalate and 5-50% by weight of polyethylene-2,6-naphthalate. When the content of polyethylene 2,6-naphthalate is less than 5% by weight, it is impossible to sufficiently suppress the change in physical properties of the fiber after spinning with time. The content of polyethylene-2,6-naphthalate is preferably at least 10% by weight, more preferably at least 15% by weight. In this case, the polyethylene terephthalate content is preferably 90% by weight or less, more preferably 85% by weight or less. On the other hand, when the content of polyethylene 2,6-naphthalene dicarboxylate exceeds 50% by weight, not only the production cost will increase, but also the filter pressure in spinning will increase, which leads to difficulty in spinning and the resulting conductive The elongation of the composite fiber will decrease. The content of polyethylene-2,6-naphthalate is preferably not more than 40% by weight, more preferably not more than 30% by weight. In this case, the polyethylene terephthalate content is preferably 60% by weight or more, more preferably 70% by weight or more.

[0027]

The conductive composite fiber of the present invention is obtained by mixing resin composition (a) comprising 60-80% by weight of thermoplastic resin and 20-40% by weight of conductive particles with 50-95% by weight of polyethylene terephthalate and 5-50% by weight The resin composition (b) of weight % polyethylene 2,6-naphthalene dicarboxylate is prepared by composite spinning. That is, the electroconductive composite fiber is produced by combining the molten resin composition (a) and the molten resin composition (b) and melt-blowing them through a composite spinneret.

[0028]

In the method of producing the electroconductive composite fiber of the present invention, a melt spinning machine generally used for producing a composite fiber can be used. At this time, in consideration of dispersibility, it is preferable to prepare the conductive layer (A) by feeding pellets of the resin composition (a) by feeding a thermoplastic resin and a conductive resin into a melt spinning machine. Granules are obtained by melt kneading. Although resin composition (b) pellets can be obtained by melt-kneading polyethylene terephthalate and polyethylene 2,6-naphthalate in advance, and then feeding the obtained pellets to melt spinning Spinning machine to prepare the protective layer (B), also allows to simultaneously feed the pellets of each material to the melt spinning machine to obtain the resin composition, and then form the protective layer (B).

[0029]

At this time, the winding speed is preferably 1500-3000 m/min. When the winding speed is lower than 1500 m/min, both the elongation and the boiling water shrinkage become too high, so that the dimensional stability deteriorates significantly. The winding speed is more preferably 1800 m/min or higher, even more preferably 2000 m/min or higher. When the winding speed exceeds 3000m/min, the fiber may break during spinning, and the elongation and boiling water shrinkage will become extremely small. Specifically, when producing conductive composite fibers that are required to have elongation or boiling water shrinkage above a certain level to be used as blended yarns, etc., it is preferable to adjust the winding speed lower, more preferably to 2600 m/min or less , even more preferably adjusted to below 2400m/min.

[0030]

During spinning, the spun yarn can be easily wound after being cooled by, for example, blowing cold air. However, in order to effectively prevent the conductive layer (A) from breaking, it is preferable to employ the spinning method shown below. That is, it is preferred to employ a method in which the following steps (1)-(5) are carried out sequentially, and steps (2) and (3) are carried out before the extruded filament contacts the guide roller or wire guide for the first time:

(1) Merge the molten resin polymer (a) and the molten resin composition (b) and melt and eject them through a composite spinneret,

(2) Temporarily cooling the ejected molten resin composition to a temperature lower than the glass transition point,

(3) subsequently transporting it through a heating device to subject it to thermal stretching,

(4) oil it afterwards, and

(5) Coil it at a speed of 1500-3000 m/min.

[0031]

The characteristic points of the above method are: after the composite polyester yarn melted and sprayed is cooled, a heating zone such as a tubular heater is then used to undergo thermal stretching treatment, and the process from the above melted spraying to thermal stretching is basically performed. Do not allow the wire to touch the guide rollers or yarn guides. By using this method, the conductive fibers are stretched without stress between the guide rollers or between the guide rollers and the guide rollers, and the draw ratio is automatically controlled in the region from the molten polymer ejection point to the inside of the heating device. As a result, the conductive fibers were not stretched to such an extent that the conductive layer (A) was broken. In addition, the conductive layer (A) is properly stretched and crystallized, and its amorphous part is in a state where it can perform molecular motion. As a result, even if tension is applied to the conductive layer (A), the conductive layer (A) is not broken and can be greatly stretched, so that the conductive property is not lost. The heating temperature for thermal stretching is preferably within a temperature range not lower than the glass transition temperature and not higher than the melting point of the resin constituting the resin composition (a), and also preferably not lower than the polyethylene terephthalate The glass transition temperature of the ester (which is the main component constituting the resin composition (b)) and the temperature range not higher than its melting point.

[0032]

As far as the cooling method in (2) is concerned, by adjusting the cooling air temperature to about 20-30 ° C, the humidity of the cooling air is adjusted to about 20-60% RH, and the blowing rate of the cooling air is adjusted to about 0.4-1m/ sec, it is possible to obtain high-quality fibers with neither denier unevenness nor performance fluctuations. In addition, for uniform and smooth stretching, it is preferable that the length of the heating zone used in (3) is not less than 0.6m and not more than 4m, and the temperature of the heating zone is not less than 150°C and not more than 220°C.

[0033]

Preferably, the weight ratio (A/B) of the conductive layer (A) to the protective layer (B) of the conductive composite fiber obtained in the present invention is 5/95-50/50. When the weight ratio (A/B) is less than 5/95, the conductivity may become insufficient and the conductive layer (A) may be broken. The weight ratio (A/B) is more preferably 10/90 or more, even preferably 15/85 or more. On the other hand, when the weight ratio (A/B) exceeds 50/50, the strength becomes insufficient and the physical properties of the fiber change significantly with time. The weight ratio (A/B) is more preferably 40/60 or less, even more preferably 30/70 or less.

[0034]

The elongation (DE) of the conductive composite fiber of the present invention is 100-350%. When the elongation (DE) is lower than 100%, the conductive layer (A) may be broken due to extremely strong stretching, and when it is used as a mixed fiber yarn, it cannot have the desired elongation or the desired boiling water shrinkage . The elongation (DE) is preferably 150% or more, more preferably 180% or more, even more preferably 200% or more. When the elongation (DE) exceeds 350%, uneven stretching will occur during blending and stretching of the fiber with another fiber, and fracture will occur in subsequent processing. The elongation (DE) is preferably 300% or less, more preferably 250% or less. Herein, elongation (DE) refers to a value measured in accordance with JIS L1013.

[0035]

The boiling water shrinkage (Wsr) of the conductive composite fiber of the present invention is preferably 20-60%. When the boiling water shrinkage ratio (Wsr) is less than 20%, the processability in processing after the fiber is blended with another fiber to be used as a blended yarn or the like deteriorates. The boiling water shrinkage ratio (Wsr) is more preferably 25% or more, and even more preferably 30% or more. On the other hand, when the boiling water shrinkage ratio (Wsr) exceeds 60%, such as in the case of woven fabrics, streaks are generated due to shrinkage, resulting in deteriorated fabrics. The boiling water shrinkage ratio (Wsr) is more preferably 50% or less, even more preferably 40% or less. Here, the boiling water shrinkage ratio (Wsr) refers to a value measured in accordance with JIS L1013.

[0036]

Although the conductive composite fiber of the present invention has a certain elongation, its fiber physical properties such as elongation or boiling water shrinkage exhibit little change with time during transportation or storage. In particular, it has a feature of showing small changes in fiber physical properties even if kept at a high temperature.

[0037]

Specifically, it is preferable that the elongation (DE ₆₀ ) at 60 days after spinning is not more than 1.3 times the elongation (DE ₁ ) at 1 day after spinning when the fiber is stored at 60°C and 80% RH, More preferably not more than 1.2 times. Here the time of 1 day after spinning was used as a starting point to detect as precisely as possible changes in fiber physical properties over time by eliminating changes in elongation (DE) due to moisture absorption or temperature changes. The elongation (DE ₆₀ ) is usually 0.9 times or more of the elongation (DE ₁ ).

[0038]

In addition, when the fiber is stored at 60°C and 80% RH, it is preferable that the boiling water shrinkage (Wsr ₆₀ ) at 60 days after spinning is not less than 0.3 times the boiling water shrinkage (Wsr ₁ ) at 1 day after spinning, More preferably not less than 0.5 times, even more preferably not less than 0.7 times. The reason why the time of 1 day after spinning is used as the starting point here is the same reason in terms of elongation. Boiling water shrinkage (Wsr ₆₀ ) usually does not exceed 1.05 times of boiling water shrinkage (Wsr ₁ ). Preferably, the fiber has a boiling water shrinkage (Wsr ₆₀ ) of not less than 10%, more preferably not less than 15%, even more preferably not less than 20% at 60 days after spinning when stored at 60°C and 80% RH.

[0039]

The conductive composite fiber of the present invention can be used in various forms and in various applications requiring antistatic properties. For example, it can be used by forming a mixed filament of the conductive multifilament and the non-conductive multifilament of the present invention so that the conductive multifilament will become the side yarn and the non-conductive multifilament will become the core yarn and the conductive multifilament will be 1-30 long %. Polyester-based multifilament is preferred as the core yarn. The total titer of the non-conductive multifilament as core yarn is preferably 20-120 dtex. In making mixed filaments, the core and side yarns are usually entangled so that they do not separate. After forming this entanglement, the resulting blended filaments can be twisted.

[0040]

It is also allowed that the non-conductive multifilament is used as the core yarn around which the conductive multifilament is helically wound. As the core yarn, one having the same thickness as in the case of the above mixed yarn is used. Also, polyester-based multifilament is preferred as the core yarn. Such multifilament yarns containing conductive fibers are arranged at a density of 1 bundle at a distance of 5 mm to 50 mm as a part of warp and/or weft in fabrics such as woven or knitted fabrics. As a result, the resulting fabric will have antistatic properties.

[0041]

In blending filaments in this way, it is possible to obtain blended filaments with excellent properties due to proper elongation (DE) and proper boiling water shrinkage (Wsr). In addition, since the physical properties of fibers change little with time over a long period of time during transportation, storage, etc., the physical properties of fibers are stable in long-distance transportation such as international transportation or long-term storage. It exhibits good processability in downstream processing such as blending, twisting, weaving, knitting, etc. and uniform products can be obtained therefrom.

[0042]

The fabrics thus obtained are used in applications where antistatic properties are required for a long time. For example, it can be used as dustproof clothing worn in clean rooms, or as antistatic overalls for workers working in places where static electricity can cause explosions, such as those working in chemical plants or workers handling chemicals. In addition, the conductive fibers of the present invention can be used as part of the pile of an antistatic carpet or as an antistatic brush of a copier.

[0043]

One application to which the conductive composite fiber of the present invention is particularly suitable is a carpet in which static electricity is generated. The conductive composite fiber of the invention is suitable for antistatic fiber in carpets. For example, in terms of nylon carpet, 2-10 conductive composite fibers of the present invention are added to about 1,000-10,000 dtex unstretched or half-stretched nylon multifilament to blend the fibers together, and the blended yarn is stretched 2-4 times. The resulting drawn yarn is processed into a woven or knitted fabric which can be processed into cut pile or looped carpet. The conductive composite fiber of the present invention is excellent in processability during stretching due to moderate elongation (DE) and slight change in fiber physical properties over time. In many cases, it takes a lot of time to go from making conductive composite fibers to making carpets and the products are often transported over long distances. Therefore, the conductive composite fiber of the present invention is suitable. Specifically, it is suitable for so-called tufted carpets made by drawing the above stretched yarns as pile yarns into a base fabric, applying latex to the back to prevent piles from coming out, and then attaching a decorative pad to on it.

Example

[0044]

The present invention will be described in more detail below with reference to Examples. The test method used in the embodiment is as follows:

[0045]

(1) Change of elongation (DE) with time

Elongation (DE) was measured in accordance with JIS L1013. The elongation (DE ₀ ) was measured just after spinning, then stored at 60° C. and 80% RH, and then the elongation (DE ₁ ) was measured 1 day after spinning. Next, storage under the above conditions was continued while repeating the assay at appropriate intervals until about 90 days thereafter. Regarding the elongation at 60 days after spinning (DE ₆₀ ), when there is no data accurately measured at 60 days after spinning, it is assumed that the elongation changes linearly before and after the 60-day test. Calculation.

[0046]

(2) Variation of boiling water shrinkage (Wsr) with time

Boiling water shrinkage (Wsr) was measured in accordance with JIS L1013. Boiling water shrinkage (Wsr ₀ ) was measured just after spinning, then stored under conditions of 60°C and 80% RH, and then boiling water shrinkage (Wsrl) was measured 1 day after spinning. Next, storage under the above conditions was continued while repeating the assay at appropriate intervals until about 90 days thereafter. With regard to the boiling water shrinkage (Wsr ₆₀ ) at 60 days after spinning, when there is no data accurately measured at 60 days after spinning, it is assumed that the elongation changes linearly before and after the 60-day test. Calculation.

[0047]

(3) Electrical conductivity

Conductive properties were determined in terms of the time when the conjugate fiber stored under the conditions of 60°C, 80% RH maintained a resistance of 10-Ω·cm or less as follows. The resistance of the composite fiber was measured using super insulation resistance measuring instruments "SM8220" and "SME8350" manufactured by DKK-TOA Corporation.

○: The above resistance was maintained for one year or more after spinning.

Δ: The above resistance is maintained for not less than 6 months but less than one year after spinning.

×: The above resistance can be maintained for less than 6 months after spinning.

[0048]

Example 1

A resin composition (a) pellet consisting of polybutylene terephthalate (PBT) containing 25% by weight of conductive carbon black was used as a raw material for the conductive layer (A). In addition, 90 parts by weight of polyethylene terephthalate (PET) pellets containing 3% by weight of titanium dioxide having an average particle diameter of 0.4 μm and 10 parts by weight of polyethylene 2,6-naphthalate ( A mixture of PEN) pellets was used as a raw material for the protective layer (B). The conductive layer (A) and the protective layer (B) weight ratio (A/B) are adjusted to 20/80 and the spinning temperature is adjusted to 285 ° C by carrying out composite spinning, so that the conductivity of the resin composition (a) The layer (A) will form the sheath and the protective layer (B) of the resin composition (b) will form the core to obtain a 38dtex/2f conductive multifilament.

[0049]

The following spinning method is adopted, the method comprising: combining the melt of the resin composition (a) and the melt of the resin composition (b), and then melt-spraying through a composite spinneret; It was temporarily cooled to a temperature lower than the glass transition point; then it was passed through a heating device to subject it to heat stretching treatment; it was then oiled; and it was wound up at a speed of 2200 m/min. In this spinning method, heat stretching treatment is performed before the above extruded filaments first contact a guide roll or a yarn guide. As a cooling method, cooling air at 25°C and 60% RH was blown onto the fibers at a rate of 0.5 m/sec just below the nozzle. Further, as a heat stretching treatment method, a method in which a heating tube having a diameter of 3 cm and a length of 1 m was arranged at 1.5 m directly below the nozzle, and 180° C. was maintained inside the tube was employed. The fiber forming performance is good and satisfactory. The elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity of the thus obtained conjugated fiber were measured as needed. The results are shown in Fig. 1, and the composition and evaluation results of the composite fibers are summarized in Table 1.

[0050]

Example 2

Conductive multifilament was obtained in the same manner as in Example 1, except that 80 parts by weight of the same polyethylene terephthalate pellets used in Example 1 and 20 parts by weight of the same polyethylene terephthalate pellets used in Example 1 were used. A mixture of polyethylene 2,6-naphthalate pellets was used as a raw material for the protective layer (B). The conjugate fibers thus obtained were evaluated in the same manner as in Example 1. The results and compositions of the obtained composite fibers are shown in FIG. 2 and Table 1.

[0051]

Example 3

Conductive multifilament was obtained in the same manner as in Example 1, except that 70 parts by weight of the same polyethylene terephthalate pellets used in Example 1 and 30 parts by weight of the same polyethylene terephthalate pellets used in Example 1 were used. A mixture of polyethylene 2,6-naphthalate pellets was used as a raw material for the protective layer (B). The conjugate fibers thus obtained were evaluated in the same manner as in Example 1. The results and compositions of the obtained composite fibers are shown in FIG. 3 and Table 1.

[0052]

Example 4

Conductive multifilament was obtained in the same manner as in Example 1, except that 50 parts by weight of the same polyethylene terephthalate pellets used in Example 1 and 50 parts by weight of the same polyethylene terephthalate pellets used in Example 1 were used. A mixture of polyethylene 2,6-naphthalate pellets was used as a raw material for the protective layer (B). The conjugate fibers thus obtained were evaluated in the same manner as in Example 1. The results and compositions of the obtained composite fibers are shown in FIG. 4 and Table 1.

[0053]

Comparative Example 1

A conductive multifilament was obtained in the same manner as in Example 1, except that only the same polyethylene terephthalate as used in Example 1 was used as the raw material for the protective layer (B). The conjugate fibers thus obtained were evaluated in the same manner as in Example 1. The results and compositions of the obtained composite fibers are shown in FIG. 5 and Table 1.

[0054]

Example 5

A conductive multifilament was obtained in the same manner as in Example 2, except that the spinning speed was changed from 2200 m/min to 1800 m/min. The elongation immediately after spinning (DE ₀ ) and the shrinkage in boiling water (Wsr ₀ ) immediately after spinning of the conjugate fiber thus obtained were measured, and the electrical conductivity was measured over time. The obtained composite fiber evaluation results are shown in Table 2 together with the composition.

[0055]

Example 6

A conductive multifilament was obtained in the same manner as in Example 2, except that the spinning speed was changed from 2200 m/min to 2900 min/m. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0056]

Example 7

Conductive multifilaments were obtained in the same manner as in Example 2, except that modified polyethylene terephthalate particles containing isophthalic acid components (accounting for 8 mol% of all dicarboxylic acid components) were used Polyethylene terephthalate pellets were replaced by polyethylene terephthalate pellets as the raw material for the protective layer (B), and the spinning speed was changed from 2200m/min to 2500min/m. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0057]

Example 8

Conductive multifilaments were obtained in the same manner as in Example 1, except that the resin composition (a) pellets made of nylon 6 (NY) containing 35% by weight of conductive carbon black were used as the raw material for the conductive layer (A) , 85 parts by weight of the same polyethylene terephthalate pellets used in Example 1 and 15 parts by weight of the same polyethylene 2,6-naphthalate pellets used in Example 1 as Raw material for protective layer (B) and spinning speed varied from 2200 to 2500 min/m. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0058]

Example 9

Obtain conductive multifilament in the same manner as Example 1, the difference is that the spinning speed is changed from 2200m/min to 2500min/m and composite spinning is carried out while the weight ratio of conductive layer (A) and protective layer (B) (A/B) was adjusted to 45/55 so that the conductive layer (A) having the same composition as in Example 1 formed the core, and the protective layer (B) having the same composition as in Example 1 formed the skin. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0059]

Example 10

Obtain conductive multifilament in the same manner as Example 1, the difference is that the spinning speed is changed from 2200m/min to 2500min/m and the weight of the conductive layer (A) and the protective layer (B) will be changed by carrying out composite spinning The ratio (A/B) was adjusted to 20/80 so that the conductive layer (A) with the same composition as in Example 1 formed islands, and the protective layer (B) with the same composition as in Example 1 formed a sea to obtain Island-in-the-sea composite fibers. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0060]

Comparative Example 2

Conductive multifilament was obtained in the same manner as in Example 1, except that 97 parts by weight of the same polyethylene terephthalate pellets used in Example 1 and 3 parts by weight of the same polyethylene terephthalate pellets used in Example 1 were used. A mixture of polyethylene 2,6-naphthalate pellets was used as the raw material for the protective layer (B) and the spinning speed was varied from 2200 to 2500 min/m. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0061]

Comparative Example 3

Conductive multifilament was obtained in the same manner as in Example 1, except that 40 parts by weight of the same polyethylene terephthalate pellets used in Example 1 and 60 parts by weight of the same polyethylene terephthalate pellets used in Example 1 were used. A mixture of polyethylene 2,6-naphthalate pellets was used as the raw material for the protective layer (B) and the spinning speed was varied from 2200 to 2500 min/m. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0062]

Comparative Example 4

Obtain conductive multifilament in the same manner as in Example 1, except that only the same polyethylene terephthalate pellets used in Example 1 are used as the raw material for the protective layer (B) and the spinning speed is from Change from 2200m/min to 2900min/m. The evaluation results of the conjugate fibers thus obtained in the same manner as in Example 5 are shown in Table 2 together with the composite fiber composition.

[0063]

[Table 1]

[0065]

As can be understood from Tables 1 and 2, when the resin composition (b) forming the protective layer (B) is composed of 50-95% by weight of polyethylene terephthalate and 5-50% by weight of polyethylene 2,6-naphthalene di Ethylene glycol formate makes the elongation (DE), boiling water shrinkage (Wsr) and electrical conductivity of the conductive composite fiber change little with time (Example 1-10). In contrast, when the content of polyethylene 2,6-naphthalate in the resin composition (b) forming the protective layer (B) is less than 5% by weight, the elongation of the conductive composite fiber ( DE), boiling water shrinkage (Wsr) and electrical conductivity change greatly with time (comparative examples 1, 2 and 4). That is, the addition effect of polyethylene-2,6-naphthalate to the resin composition (b) forming the protective layer (B) is remarkable.

[0066]

Drawn was prepared by blending the conductive multifilament yarn (38dtex/2f) obtained in Example 1 with a 3,500-dtex undrawn multifilament yarn composed of nylon 6,6, and then stretching the blended yarn 2.6 times Multifilament yarn. Furthermore, a base fabric was prepared by using the conductive multifilament obtained in Example 1 as a component. Tufted carpets were prepared by sewing the above drawn multifilament yarns as pile yarns to the base fabric, then applying synthetic latex to the back surface, and attaching a decorative backing. In this production process, especially in the drawing process, breakage of the conductive composite fiber was not observed at all and there was no failure caused by the conductive composite fiber during the production process. When the resulting carpet was laid on the floor of a particularly dry room in winter and repeatedly walked over it, no static electricity was generated at all. In addition, no bad feeling due to static electricity was felt when hands touched the carpet.

Claims (10)

[1] A conductive composite fiber obtained by combining a conductive layer (A) containing 60-80% by weight of a thermoplastic resin and 20-40% by weight of conductive particles with 50-95% by weight of polyethylene terephthalic acid The protective layer (B) of ethylene glycol ester and 5-50% by weight of polyethylene-2,6-naphthalate is compounded, wherein the elongation (DE) of the fiber is 100-350%. [2] The conductive composite fiber according to claim 1, wherein the thermoplastic resin constituting the conductive layer (A) is polybutylene terephthalate or polyamide. [3] The conductive composite fiber according to claim 1 or 2, wherein the weight ratio of the fibrous conductive layer (A) to the protective layer (B) is 5/95-50/50. [4] The conductive composite fiber according to any one of claims 1 to 3, wherein the fiber has a boiling water shrinkage ratio (Wsr) of 20 to 60%. [5] The conductive composite fiber according to any one of claims 1 to 4, wherein when the fiber is stored at 60°C and 80% RH, the elongation (DE ₆₀ ) at 60 days after spinning is not more than 60 days after spinning. 1.3 times the elongation (DE ₁ ) at 1 day after silk. [6] The conductive composite fiber according to any one of claims 1 to 5, wherein when the fiber is stored at 60°C and 80% RH, the shrinkage in boiling water (Wsr ₆₀ ) at 60 days after spinning is not less than 0.3 times the boiling water shrinkage (Wsr ₁ ) one day after spinning. [7] The conductive composite fiber according to any one of claims 1 to 6, wherein when the fiber is stored under conditions of 60°C and 80% RH, the shrinkage in boiling water (Wsr ₆₀ ) at 60 days after spinning is 10% above. [8] A carpet in which fibers obtained by drawing the conductive composite fibers according to any one of claims 1 to 7 are used. [9] A method for producing a conductive composite fiber, the method comprising mixing a resin composition (a) comprising 60-80% by weight of a thermoplastic resin and 20-40% by weight of conductive particles with a polyparaphenylene compound comprising 50-95% by weight The resin composition (b) composite spinning of ethylene glycol diformate and 5-50% by weight polyethylene 2,6-naphthalene dicarboxylate, wherein the molten resin composition (a) and the molten resin composition ( b) merged, melted and sprayed through the composite spinneret, and then wound at a speed of 1500-3000m/min. [10] The method for preparing conductive composite fibers according to claim 9, wherein the following steps (1)-(5) are carried out in sequence, and the steps (2) and (3) are carried out before the ejected filament contacts the guide roller or the wire guide for the first time : (1) Merge the molten resin polymer (a) and the molten resin composition (b) and melt and eject them through a composite spinneret, (2) Temporarily cooling the ejected molten resin composition to a temperature lower than the glass transition point, (3) subsequently conveying it through a heating device to subject it to thermal stretching, (4) oil it afterwards, and (5) Coil it at a speed of 1500-3000m/min.

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