JP2008261072A - Method for producing low dusting conductive yarn - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a conductive yarn that is obtained by being coated with a conductive polymer composed of a polypyrrole for prevention of static charge, and has low dusting properties. <P>SOLUTION: The method for producing a low dusting conductive yarn includes (a) the step of impregnating a charged yarn with an aqueous solution of a dopant-containing oxidizing agent, (b) the step of bringing the impregnated yarn into contact with a vapor-phase pyrrole monomer and at least partially covering the yarn with a polypyrrole formed by the oxidation polymerization and (c) the step of treating the yarn at least partially coated with the polypyrrole with an emulsion, dispersion or solution of a binder resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a conductive yarn coated with a conductive polymer such as polypyrrole for antistatic purposes, and more particularly to a method for producing a conductive yarn which generates less dust from the antistatic yarn in its use. Such a yarn is useful as a conductive yarn for producing a wiping cloth for use in a clean room that handles precision electronic components, for example.

  The conductive yarn is also used for a conductive brush used in an image forming apparatus such as a laser printer. The conductive yarn reported so far is a mixture of a polymer such as polyolefin, polyester, or polyamide and a conductive material such as carbon or conductive metal oxide.

JP 2006-152491 A JP 2006-336142 A JP2007-9335 JP2007-34196 JP 2006-316373 A

  There is a method in which a fabric or non-woven fabric formed into a sheet such as a wiping cloth is coated with a conductive polymer such as polypyrrole to prevent electrification. Applicant's Japanese Patent Application No. 2005-369058 discloses such a method. However, the coating of polypyrrole on the surface of the yarn is not disclosed.

  The imparting of conductivity to the yarn by compositing a conductive polymer is generally performed by polymerizing a monomer on the yarn and covering the yarn at least partially with the conductive polymer. In the case of polypyrrole, the yarn is immersed in the pyrrole monomer solution and held in that state, and then immersed in the oxidizer and dopant solution, or the yarn is immersed in a solution containing the oxidizer and dopant, and the state A liquid phase method in which the polymer is held by being immersed in a monomer solution and then polymerized, and a gas phase method in which the yarn is pre-impregnated with a solution of an oxidant and a dopant, and a pyrrole monomer in a gas phase is brought into contact therewith to polymerize the monomer. One of these is adopted. The vapor phase method has an advantage that conductive polymer particles grown to a nano-level size can be attached to the fiber.

  Whether the liquid phase method or the gas phase method is used, the yarn treated by the above method is easy to drop off due to mechanical impact of the conductive polymer as a particle, and as such it turns out to be a source of dust. It was. Therefore, an effective measure for reducing the dust generation property of the yarn coated with the conductive polymer to a practically acceptable level is desired.

The present invention provides a yarn coated with a conductive polymer that exhibits low dusting properties. According to the present invention, the charged yarn is pre-treated with an oxidant solution containing a dopant and is contacted with a vapor phase pyrrole monomer to coat the yarn with a polypyrrole conductive polymer containing the dopant. Furthermore, in order to show low dust generation property, the conductive polymer coated with the yarn is treated with a binder resin that strengthens the adhesion of the conductive polymer to the yarn in order to prevent the conductive polymer coated with the yarn from falling off. A molecular coated yarn is produced. The treated yarn is coated with a conductive polymer at least partially coated thereon and a binder resin that enhances adhesion of the conductive polymer to the yarn. Desirably, either the conductive polymer or the binder resin is a matrix, the other is surrounded by the matrix and the yarn is covered with both, and the electrically conductive yarn is 10 ¹¹ Ω / □. It is desirable to have a resistivity below the order. In order to achieve this, it is important to adopt a polymerization reaction of the pyrrole monomer in the gas phase and control the conductive polymer to be generated to be nano-sized, and to properly control the binder resin pickup rate. It is.

  According to the present invention, the polymerization reaction is preferably controlled by adjusting the pH of the oxidant solution containing the dopant to a range of 4 to 9, or copolymerizing a pyrrole derivative having a polymerization reaction rate lower than that of pyrrole, or both. The control of the pickup rate can be achieved by adjusting the solid content of the binder resin used in solvent-type normally dry paints or emulsion-type or dispersion-type water-based paints. can do.

  Here, some terms used in the present application are defined.

  “Yarn” refers to a multifilament yarn composed of natural fibers, synthetic or semi-synthetic chemical fibers, and mixtures thereof. In order to allow the treatment agent according to the present invention to be accepted, there must be a fine gap between the fibers. In particular, the yarn material intended for use in a wiping cloth that can be used in a class 100 ultra-clean room is preferably made of split fibers, ultrafine fibers, typically ultrafine polyester fibers.

  “Polypyrrole” is not only a homopolymer of pyrrole but also a small proportion of pyrrole homologues or derivatives copolymerizable with pyrrole, such as N-methylpyrrole, 3-methylpyrrole, 3,5-dimethylpyrrole, 2,2 '-Refers to a copolymer with bipyrrole.

  “Oxidizing agent” refers to a chemical oxidizing agent capable of providing conductive polypyrrole by oxidative polymerization of pyrrole monomers. Specific examples of oxidizing agents that can be used are described in US Pat. Nos. It is described in a number of documents including 4,604,427, 4,521,450 and 4,617,228, ammonium persulfate, iron (III) chloride, iron (III) sulfate, hydrogen peroxide, perboric acid Including ammonium and copper (II) chloride. A sulfonic acid used as a dopant, for example, a ferric salt of paratoluenesulfone, can also be used as an oxidizing agent.

  "Dopant" refers to an anion that improves the conductivity of polypyrrole, examples of which are also described in numerous patent documents, including the aforementioned US patents. Preferred are sulfonic acids such as paratoluenesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, dodecylbenzenesulfonic acid, and sulfonated polystyrene.

  “Binder resin” refers to a resin component used as a film-forming resin in a normally dry water-based paint in the form of a solvent-type normally dry paint or emulsion or dispersion. Specific examples include vinyl resins including homo- or copolymers such as vinyl chloride, vinyl acetate, and vinylidene chloride, acrylic resins, polyester resins, epoxy resins, polyamide resins, fluororesins, and modified resins thereof. In consideration of the affinity, it is preferable to employ a polyester binder resin for a binder resin similar to the fiber constituting the substrate, for example, a polyester fiber. Polyurethane emulsions or dispersions have good adhesion to various types of fibers. Furthermore, it is possible to improve heat resistance and durability by using a curing agent that reacts with a functional group at the molecular end of these binders.

As mentioned above, one of the important aspects of the present invention is that 90% or more of the primary particles are coated with polypyrrole having a size of 100 nm or less by employing gas phase polymerization. The polymerization reaction rate of the pyrrole monomer depends on the pH of the oxidant solution containing the dopant, and is usually controlled on the acidic side, particularly in the range of pH 1 to 3. According to a more preferred embodiment, the pH of this solution is controlled in the range of 3-11, more preferably pH 4-9. Among the oxidizers mentioned above, there are those in which the aqueous solution originally exhibits acidity, such as ferric chloride and ferric sulfate, and Fe ³⁺ ions cannot be stably present in the solution by neutralization. There is. In view of this, in this case, it is necessary to select an oxidizing agent that is stable at a pH of 6 to 9, such as ammonium persulfate and ammonium perborate. Another method for controlling the polymerization reaction rate is a method in which a comonomer having a slower reaction rate than pyrrole itself is copolymerized. For example, N-methylpyrrole is known to have a slower reaction rate than pyrrole. Therefore, a small proportion, for example, pyrrole containing 10 mol% or less of N-methylpyrrole is used for the polymerization reaction.

In order to control the influence on properties such as adhesion, particle size of polypyrrole, and dust generation properties when pyrrole is vapor-phase polymerized with yarn, the optimal combination and blending of oxidizing agent and dopant have been studied. Absent.
Furthermore, depending on the specific combination of the dopant and the oxidizing agent, the impregnating liquid may not exist stably. The present inventor, when using aromatic sulfonic acid as a dopant, can achieve satisfactory adhesion, polyparticle size, low by using water-soluble persulfate such as ammonium persulfate or alkali metal salt. It has been discovered that pyrrole can be vapor-phase polymerized on yarn with a dusting polypyrrole. The combination of aromatic sulfonic acid and persulfate is stable in a wide pH range from an acidic range to an alkaline range in an aqueous solution.

  The yarn is then impregnated with an oxidant solution containing a dopant, which can be carried out by dipping, spraying, coating, or the like. It is desirable to squeeze the excess solution with mangle roll or the like. The concentrations of dopant and oxidant are not critical and are preferably 0.1 to 10%, preferably 0.5 to 5%, especially about 1%.

  The yarn thus impregnated with the oxidant solution containing the dopant is brought into contact with the vapor phase pyrrole monomer. The monomer contacts the wetted yarn with an oxidant solution containing a dopant and forms a polypyrrole conductive polymer coating thereon. In this gas phase polymerization reaction, a yarn impregnated with an oxidizing agent containing a dopant is placed in a partitioned reaction chamber, and the monomer is introduced into the gas phase therein and left in that state until the monomer no longer reacts. Can be implemented. In some cases, including the impregnation step, the gas phase polymerization reaction may be carried out continuously.

  Although the boiling point of pyrrole at atmospheric pressure is 130 ° C., it vaporizes in air until reaching the saturated vapor pressure even at a temperature lower than that. Therefore, an evaporator of liquid pyrrole is installed in the reaction chamber, vaporized pyrrole and liquid pyrrole are maintained in an equilibrium state, and a yarn impregnated with an aqueous oxidizing agent solution containing a dopant is held in this state of the atmosphere. Alternatively, an evaporator containing liquid pyrrole can be installed outside the room, bubbled with an inert carrier gas such as nitrogen, and vaporized pyrrole can be supplied into the room together with the carrier gas. Regardless of where the evaporator is installed, the temperature of the liquid pyrrole may be in the range of 5 ° C to 100 ° C, preferably 20 ° C to 50 ° C, particularly preferably room temperature. Unlike the liquid phase method, the gas phase method has a limited amount of oxidant required for the reaction, and therefore it is not necessary to strictly control the reaction time.

The oxidative polymerization of pyrrole reaches equilibrium and spontaneously stops as the oxidant contained in the impregnated yarn is consumed. By such treatment, the surface resistivity of the yarn can be reduced to the order of 10 ¹¹ Ω / □ or less. If the resistivity does not reach this value, the impregnation and gas phase polymerization steps described above can be repeated until the desired resistivity is reached. The treated yarn is washed to remove remaining dopants and used for the next step.

  The adhesion rate of the conductive polymer, i.e. the weight percent of the conductive polymer relative to the yarn before treatment, will vary greatly depending on the nature of the yarn, particularly the specific surface area of the yarn, but will generally be 0.1-5%.

  Thus, the conductive polypyrrole adhering to the yarn falls off from the yarn due to mechanical impact and can itself become a source of dust. The present invention therefore uses a binder resin to enhance the adhesion of the conductive polymer to the yarn. As described above, in this case, it is important to appropriately control the binder resin pickup rate, that is, the weight percentage of the binder resin in terms of solid content with respect to the yarn. This pickup rate is also related to the adhesion rate of the conductive polymer previously deposited. In other words, it should not be so large that the resistivity of the yarn coated with the conductive polymer in the previous step is increased to a resistivity higher than the desired level, and conversely significantly enhances the adhesion of the conductive polymer to the yarn. The amount should not be insufficient. This pickup rate varies greatly depending on the material and structure of the specific yarn used and the affinity of the specific binder resin for the yarn, but generally 0.01 to 2.0% by weight of the yarn as the solid content. Within the range, the ratio of binder resin to conductive polymer will be in the range of 0.01 to 3.00, preferably 0.1 to 1.0.

  Such control of the pickup rate of the binder resin can be easily achieved by using an emulsion or dispersion of the binder resin. In this case, the solid content concentration of the emulsion or dispersion is diluted to 5% or less, for example, 1% with water, the yarn obtained in the previous step is immersed in this solution, and the excess liquid is squeezed out arbitrarily and then dried. And shipped as a final product. In this case, in order to improve heat resistance and durability, a curing agent that reacts with a functional group at the molecular end of these binders can be used in combination. If the pick-up rate is insufficient, dipping and drying may be repeated again. Although it is a suboptimal method, the adhesion of the conductive polymer to the yarn can be enhanced by spraying an organic solvent solution of a binder resin such as a solvent-type ordinary dry paint. The pickup rate in this case can be controlled by adjusting the resin solid content concentration of the solution and / or the spray amount per unit area.

  The following examples and comparative examples are not intended to be limiting, and “parts” and “%” are by weight unless otherwise specified.

  The surface resistivity was measured using a surface resistance meter HIRESTA-UP MCP-Hi450 manufactured by Mitsubishi Chemical Corporation.

  The number of departicles was measured using a particle counter KM-33 manufactured by Rion. Measurement conditions were based on the standard tumbler method of IES-RP-CC-003 in the United States, measured on five 10 m yarn samples, and obtained the average value of five points as the number of particles generated per one.

  The observation of the polypyrrole particle diameter on the yarn was carried out using a scanning probe microscope NANO-R stage manufactured by Pacific Nanotechnology.

Example 1
A polyester filament of 24 filaments and 75 denier 1,000 m was immersed in an aqueous solution (pH 1.40) of 1% ammonium persulfate and 1% paratoluenesulfonic acid. Thereafter, excess solution was removed with a mangle. The wet yarn was put into the reaction chamber, the vapor of pyrrole was filled into the chamber from an evaporator installed in the chamber, and left for 1 hour to perform vapor phase polymerization of pyrrole. After completion of the reaction, the yarn is taken out from the reaction chamber, washed 3 times with 1 L of distilled water, drained, immersed in 1% polyester aqueous dispersion (Toyobo's Bailonal MD1480) for 1 minute, drained, and 150 ° C. For 1 minute. From the weight difference before and after the treatment, the polypyrrole adhesion rate and the binder polyester resin pickup rate were calculated to be 1.0% and 0.2%, respectively.

A frame having a length of 10 cm and a width of 5 cm was prepared using SUS having a diameter of 2 mm, and the conductive yarn 100 m obtained was wound around the width direction of the frame. When the average surface resistivity and the average number of departicles were measured, they were 1 × 10 ⁶ Ω / □ and 35/100 m, respectively. In addition, the average number of particles removed from the untreated yarn was 26 pieces / 100 m.
Moreover, when the primary particle diameter of the polypyrrole of the location where the binder is not adhered was observed, 90% or more was 10-50 nm in size.

Example 2
The procedure of Example 1 was repeated except that a 1% aqueous melamine resin solution (Bekkamin APM manufactured by Dainippon Ink & Chemicals, Inc.) was added to a 1% polyester aqueous dispersion and applied as a binder. The polypyrrole adhesion rate and binder polyester / melamine cured resin pickup rate were calculated to be 1.0% and 0.3%, respectively. The obtained conductive yarns had an average surface resistivity and an average number of departicles of 5 × 10 ⁶ Ω / □ and 23/100 m, respectively.
Moreover, when the primary particle diameter of the polypyrrole of the location where the binder is not adhered was observed, 90% or more was 10-50 nm in size.

Example 3
The procedure of Example 2 was repeated except that the oxidant-impregnated solution containing the dopant was changed to an aqueous solution adjusted to pH 9.0 with 1% ammonium persulfate, 1% paratoluenesulfonic acid, and ammonia. The adhesion rate of polypyrrole and the pickup rate of binder polyester resin were calculated as 0.8% and 0.3%, respectively. The obtained conductive yarn had an average surface resistivity and an average departicle number of 8 × 10 ⁵ Ω / □ and 17/100 m, respectively.
Moreover, when the primary particle diameter of the polypyrrole of the location where the binder has not adhered is observed, 90% or more was 10-40 nm in size.

Comparative Example 1
A 24 filament, 75 denier polyester yarn (1000 m) was immersed in an aqueous solution of 1% ammonium persulfate and 1% paratoluenesulfonic acid adjusted to pH 0.3 with sulfuric acid, and the excess solution was removed with a mangle. Thereafter, it was immersed in a pyrrole solution for 10 minutes for polymerization. After completion of the reaction, the fiber was washed 3 times with 1 L of distilled water and dried at 105 ° C. for 1 hour. From the weight difference before and after treatment, the polypyrrole adhesion rate was calculated to be 1.2%.
The obtained fiber was wound around a SUS frame in the same manner as in Example 1, and the average surface resistivity and the average number of departicles were measured and found to be 3 × 10 ⁷ Ω / □ and 185/100 m, respectively.
Moreover, when the primary particle diameter of polypyrrole was observed, 90% or more was the size of 10-100 nm.

Comparative Example 2
The procedure of Comparative Example 1 was repeated, except that it was immersed in an aqueous solution adjusted to pH 0.8 with sulfuric acid and the excess solution was removed with mangle and immersed in a pyrrole solution for 20 minutes. From the weight difference before and after treatment, the polypyrrole adhesion rate was calculated to be 1.2%.
When the average surface resistivity and average departicle number of the obtained yarn were measured, they were 1 × 10 ⁷ Ω / □ and 147/100 m, respectively.
Moreover, when the primary particle diameter of polypyrrole was observed, 90% or more was the size of 10-100 nm.

Claims (11)

(A) impregnating the chargeable yarn with an aqueous oxidizing agent solution containing a dopant;
(B) contacting the impregnated yarn with a gas phase pyrrole monomer and at least partially covering the yarn with polypyrrole produced by oxidative polymerization; and (c) a binder resin with the yarn at least partially coated with polypyrrole. A process for producing a low dusting conductive yarn, comprising the step of treating with an emulsion, dispersion or solution of   The method of claim 1, wherein in step (b), the adhesion of polypyrrole to the yarn is adjusted to 0.1 to 5 wt%.   The method according to claim 1 or 2, wherein in step (c), the pickup rate of the binder resin with respect to the yarn as solid content is adjusted to 0.01 to 3 wt%.   The method according to claim 2, wherein in step (c), the weight ratio of the binder resin to the adhesion of polypyrrole to the yarn is adjusted to 0.01 to 3.00.   The method according to any one of claims 1 to 4, wherein in the step (a), the pH of the oxidizing agent aqueous solution containing the dopant is 4 to 9.   The method according to any one of claims 1 to 4, wherein in step (b), the pyrrole monomer contains a small proportion of a pyrrole homologue or pyrrole derivative.   The method according to any one of claims 1 to 6, further comprising a step of washing and drying the yarn between the steps (b) and (c).   The method according to any one of claims 1 to 7, further comprising the step of drying the yarn after the step (c). The method according to claim 1, wherein the surface resistivity of the conductive yarn is on the order of 10 ¹¹ Ω / □ or less.   10. The method according to claim 1, wherein the chargeable yarn is a multifilament yarn spun from a chargeable polymer. (A) impregnating the chargeable yarn with an aqueous solution of a dopant and an oxidizing agent;
(B) contacting a vapor phase pyrrole monomer with the impregnated yarn in a partitioned reaction chamber and oxidatively polymerizing polypyrrole containing a dopant on the yarn surface;
The manufacturing method of the electrically conductive yarn containing this.