JP2006097145A - Fiber composite material and use thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber product having good conductive performance even by a surface resistivity measuring method and excellent antistatic performance and durability. <P>SOLUTION: The fiber composite material contains a conductive conjugate fiber composed of a conductive thermoplastic component and a fiber-forming component. The conductive conjugate fiber has a conjugate structure to cover ≥50% of the fiber surface with a thermoplastic polymer containing carbon black and an elongation at break of 80-250% and is produced by conjugated melt spinning. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a textile product used mainly for the purpose of suppressing electrostatic charging.

  Fabrics made of synthetic fibers are generally used in various fields because they are generally superior in strength and durability compared to fabrics made of natural fibers. However, fabrics made of synthetic fibers have the disadvantage of being easily charged. In recent years, it has become clear that dust in the air has a great influence on the performance of products as the performance of products in the manufacture of medical products, medicines, foods, electronic devices, precision devices, and the like advances. For example, bringing into a manufacturing environment with dust adsorbed by electrostatic charging of clothes leads to a decrease in production efficiency. In addition, in an environment where fires and explosions are likely to occur, sparks due to static electricity are likely to occur, and there is a risk of danger, and textile products using fabrics with anti-static measures at various manufacturing sites are essential. It has become.

  Specifically, a dust-proof garment and a shoe inner layer material made of a fabric with countermeasures against static electricity are used for, for example, work clothes and work shoes in a clean room. Suppressing static electricity accumulated in clothes and the human body, preventing destruction of microcircuits due to electric discharge, suppressing adsorption of dust due to static electricity on clothes and human body, and improving the product yield by not bringing dust into the clean room Because of that. In addition, fabrics with countermeasures against static electricity are highly useful as filter materials. This is to suppress static electricity generated by friction with the filter when filtering flammable liquid or gas and to avoid flammable explosion.

  Conventionally, various methods have been devised as countermeasures against static electricity of fabrics. For example, a method of attaching a surfactant to the fabric surface by post-processing, a method of forming a fabric with antistatic fibers mixed with a hydrophilic polymer, and the like are common. However, none of these fabrics has low washing durability and antistatic performance under low humidity. Therefore, a fabric in which conductive fibers are mixed at a certain ratio is usually used.

  As the conductive fiber, a conductive composite fiber having a conductive component composed of conductive particles and a thermoplastic component as a core component (island component) and a fiber-forming component as a sheath component (sea component) is used as a process passability or It is common in terms of washing durability.

  In recent years, mainly in Europe and the United States, as a means to evaluate the antistatic performance without destroying textile products, a method of measuring the resistance value between electrodes by applying electrodes to two locations on the surface of textile products (hereinafter referred to as surface resistance measurement method) Is being spread. With this method, when the exposed area of the conductive component on the surface of the conductive fiber mixed with the textile product is small, although the anti-static performance as an actual product is sufficient, the conductive component and the electrode Since there is no contact, the conductive performance of the fabric surface is lowered, and there is a problem that the antistatic performance is judged to be poor.

  For example, Patent Document 1 discloses a woven fabric in which a conductive yarn covered with a synthetic composite fiber is used as a core synthetic fiber long yarn to improve the conductive performance, and the contact between the conductive yarns is improved. Proposals have been made. However, if the exposure of the conductive component to the fiber surface is small, contact between the conductive components and between the electrodes cannot occur, unless a permeable conductive adhesive is used to reduce contact resistance. It is difficult to obtain good conductive performance in the surface resistance measurement method.

  In order to eliminate this defect, it is easily considered that the surface layer may be a conductive component, and various proposals have been made. For example, a method of coating or plating a metal component such as titanium oxide or cuprous iodide or a conductive component in which conductive carbon particles are dispersed has been proposed. Is not durable in washing and has high conductive performance in the initial evaluation, but repeated washing causes peeling and removal of conductive components, which not only lowers the conductive performance but also promotes self-dusting. It is difficult to provide a lot of laundry indispensable applications such as dustproof clothing used in a clean room.

Japanese Patent Laid-Open No. 11-350296

  An object of the present invention is to provide a textile product that can obtain good conductive performance even in a surface resistance measurement method and is excellent in antistatic performance and durability.

  The above-mentioned problem is a fiber composite in which conductive composite fibers composed of a conductive thermoplastic component and a fiber-forming component are mixed, wherein the conductive composite fibers are made of a thermoplastic polymer containing carbon black. Use of a fiber composite characterized in that it is a conductive composite fiber having a composite structure in which the plastic component covers 50% or more of the fiber surface and having a breaking elongation of 80 to 250%, and is melt-spun. To solve.

  Moreover, as a preferable aspect of the present invention, a conductive composite fiber in the fiber composite is 0.1 to 15% by weight. Furthermore, specific applications of the fiber composite of the present invention include dust-proof clothing, shoe inner layer materials, and filters.

  According to the present invention, a fiber product excellent in conductive performance and durability can be obtained.

  The conductive conjugate fiber used in the present invention will be described. Hereinafter, the conductive thermoplastic component may be simply referred to as “conductive component”, and the fiber-forming component may be referred to as “non-conductive component”.

  The thermoplastic polymer used for the conductive component and non-conductive component of the conductive composite fiber used in the present invention includes all known fiber formations such as polyesters, polyamides, polyolefins and copolymers thereof. A thermoplastic polymer having a function can be used and may be appropriately selected. It is desirable that the base yarn occupying most of the fabric, that is, the same material as that of the fiber mixed with the conductive composite fiber, because the need to pay special attention in dyeing and other subsequent processes is reduced.

  The thermoplastic polymer used for the conductive component and the non-conductive component is preferably the same kind of thermoplastic polymer from the viewpoint of the adhesiveness of both components. Even when the two thermoplastic polymers are different from each other, a compatibilizer may be mixed into both or one of the components to improve the adhesion. For example, in the case of polyamide and polyolefin, the adhesiveness can be improved by mixing a small amount of maleic acid-modified polyolefin as a compatibilizer on the polyolefin side.

  The conductive component is composed of a thermoplastic polymer in which conductive carbon black is uniformly mixed according to a conventional method. The mixing ratio of conductive carbon black varies depending on the polymer used and the type of carbon black, but is usually 10 to 50% by weight, particularly preferably 15 to 40% by weight.

  The breaking elongation of the conductive conjugate fiber used in the present invention needs to be in the range of 80 to 250%. In the conductive conjugate fiber, as the elongation at break decreases, the conductive performance tends to decrease. The fact that the elongation at break is small means that a force is applied in the direction of stretching the fiber in the production process such as spinning and drawing, and as a result, the distance between the conductive particles contained in the conductive component is reduced. It is considered that the conductive performance is lowered due to the increase.

When the elongation at break is 80% or more, the filament resistance is less than 1.0 × 10 ⁸ Ω / cm · f, which satisfies 10 ⁶ Ω / □ or less, which is widely adopted as a standard for antistatic fabric in surface resistance measurement. It becomes possible. On the other hand, it is more desirable to set the breaking elongation higher because the filament resistance is lowered and the amount of conductive fibers used in the fiber composite can be suppressed. However, if the elongation at break exceeds 250%, the molecular orientation is insufficient, the strength is remarkably low, and not only is it easy to break during the combined yarn or twisting process, but it is easily stretched with low stress to lower the conductivity. Therefore, there is a high risk that the filament resistance becomes 1.0 × 10 ⁸ Ω / cm · f or more at the stage of forming a fabric through the process of combining or twisting.

  From the viewpoints of maintaining the conductive performance and passing through the process, the elongation at break is in the range of 80 to 250%, and 100 to 200% can be more suitably used.

  The production method for obtaining the elongation at break of the present invention is not particularly defined. That is, it is possible to draw an undrawn yarn at a relatively low magnification in accordance with a so-called conventional method. On the other hand, the take-up speed is increased, and the desired breaking elongation can be obtained even as a highly oriented undrawn yarn. The same applies to the spin draw method at a low magnification.

  In addition to conductive and non-conductive components, dispersants (waxes, polyalkylene oxides, various surfactants, organic electrolytes, etc.), colorants, heat stabilizers (antioxidants, UV absorbers, etc.), Fluidity improvers, fluorescent brighteners and other additives can be added as needed.

  The composite form of the conductive composite fiber used in the present invention is not particularly limited, but 50% or more of the fiber surface must be coated with a conductive component. Examples of the cross-sectional shape include those shown in FIGS. Among these, what is shown in FIG. 1 is a composite conductive fiber having a core-sheath structure, and the sheath component is a conductive component. Moreover, in FIG.2, 3, the structural example of the composite fiber which arranged about 4-8 conductive components on the fiber surface was shown. By using the conductive composite fiber having such a structure, the contact between the conductive components between the conductive fibers and the contact between the conductive component and the measuring instrument electrode are improved, and the surface resistance measurement method is good. Conductive performance can be obtained.

Speaking from the original purpose, the higher the exposure rate of the conductive component to the fiber surface is preferable, but the conductive component is completely covered because the melt fluidity is remarkably lowered by the inclusion of conductive carbon black. If the technical difficulty is high, and it is judged that there is sufficient contact from the electrode size of the measuring instrument used in the surface resistance measurement method and the fiber diameter of the composite fiber, and if more than 50% of the fiber surface is covered Can be said to be achieved. Conversely, when the coverage of the fiber surface of the conductive component is less than 50%, the contact between the electrode and the conductive component is uncertain, and the surface resistance measurement result tends to indicate a very large value. is there. As a result, the average value also increases, and the target value of 10 ⁶ Ω / □ or less cannot be achieved. In order to obtain a stable surface resistance value, the coverage is required to be 50% or more, more preferably 60% or more, and particularly preferably 65% or more.

  About the composite ratio of a conductive component and a non-conductive component, it is preferable that the volume ratio is conductive component: non-conductive component = 1: 20-2: 1. From the viewpoint of securing the physical properties of the fiber, it is preferable that the ratio of the non-conductive component is large. However, when the ratio of the conductive component is small, it becomes difficult to obtain a stable composite form, and accordingly, the conductivity stability is reduced. Considering these matters, the conductive component: non-conductive component = 1: 20 to 2: 1 is preferable, and 1:15 to 1: 1 is more preferable.

  It is important that the conductive conjugate fiber used in the present invention is produced by a melt conjugate spinning method. For example, in a composite fiber in which a similar composite form is formed by post-processing by a prescription such as a coating, the durability is insufficient, and peeling and dropping off of the conductive component occur when repeated washing is performed on the product. By being produced by the melt composite spinning method, sufficient durability can be exhibited even in applications that require many washings, such as a dust-proof garment used in a clean room or the like.

In the fiber composite of the present invention, other fibers (hereinafter referred to as “non-conductive fibers”) are mixed with the conductive fibers described above. Any fiber can be used as the other fiber mixed with the conductive composite fiber. Examples thereof include synthetic fibers such as nylon, polyester, and acrylic, and natural fibers such as cotton, silk, and wool. Further, a mixture of a plurality of fibers may be used.
Among these, the use of synthetic fibers is preferable in consideration of the use of the fiber composite. This is because synthetic fibers have higher strength and durability than natural fibers.

  There is no particular limitation on the method of mixing the conductive conjugate fiber and the non-conductive fiber. For example, it is possible to drive the conductive conjugate fiber alone into a woven fabric or knitted fabric at regular intervals, and depending on its fineness, the conductive composite fiber may be driven into the fabric after being twisted or twisted with the nonconductive fiber. Further, it can be cut to a predetermined length and blended with other short fibers, or may be mixed as a sewing thread with an existing fabric.

  As a usage-amount of the electroconductive composite fiber in the fiber composite of this invention, 0.1 to 15 weight% is preferable. Within this range, an antistatic effect due to corona discharge is sufficient, and process passability is excellent, which is preferable.

  The dust-proof garment of the present invention is composed of the above-described fiber composite fabric, knitted fabric or the like. It is preferable to use a filament as the base yarn from the viewpoint of suppressing the dust generation amount of the fabric itself. When using spun yarn, it is preferable to suppress self-dusting by laminating or the like.

  The structure of the fabric is not particularly limited, but a high density is preferable from the viewpoint of preventing dust permeability. However, if the density is too high, the feeling of wearing is inferior, and therefore the structure and density may be set according to the purpose. Furthermore, if necessary, the fabric is pressed by calendering, etc. to increase the denseness, and the water and quick-drying and antibacterial properties for improving the feeling of wear are promoted to accelerate the decay of the charged voltage of the fabric and fabric. Various functional fibers such as antistatic fibers can be used together.

  By using the dustproof garment of the present invention, it is possible to suppress static electricity accumulated in clothes under any environment, prevent destruction of microcircuits due to discharge, suppress dust adsorption due to static electricity, and do not bring dust into the clean room. Can improve the product yield. Moreover, since the antistatic performance can be predicted by measuring the surface resistance of the product, it is possible to perform simple quality control without destroying the product.

  The shoe inner layer material of the present invention is composed of the above-described fiber composite fabric, nonwoven fabric, or the like. As the non-conductive fiber, polyamide having excellent wear durability is mainly used, but is not particularly limited. Using a heat-adhesive fiber or a composite fiber in which a low-melting-point polymer is disposed on the sheath, a point-bonding process can be performed to maintain the three-dimensional structure and to reduce the impact.

When the conductive conjugate fiber according to the present invention is used as a nonwoven fabric, the single yarn fineness is preferably 8 dtex or less. This is because when the single yarn fineness is reduced, the number of fibers mixed even at the same weight mixing ratio is increased, the probability that the conductive conjugate fibers are in contact with each other increases, and the conductive performance in the fabric surface (horizontal direction) and in the vertical direction is improved. On the other hand, in the case of a composite fiber, if the single yarn fineness is too small, there are many cases where the production process is greatly hindered. In particular, in the case of conductive conjugate fibers, the tendency is remarkable because the melt viscosity of the conductive component and the non-conductive component are greatly separated from each other. Is preferably 0.3 dtex or more, and 0.8 dtex or more is considered particularly suitable.

  By using the shoe inner layer material of the present invention, the inner layer material itself is prevented from being charged, and if a conductive resin is used for the sole part of the shoe, static electricity accumulated in the human body through the inner layer material and the sole is used. Can be leaked to the ground. As a result, improvement in work efficiency in a clean room can be expected as in the case of dust-proof clothing.

  The filter of the present invention is composed of the above-described fiber composite fabric, nonwoven fabric, or the like. Similar to the shoe inner layer material, it is possible to improve the dimensional stability by maintaining the three-dimensional structure by applying a point-bonding process using a thermo-adhesive fiber or a composite fiber with a low melting point polymer in the sheath. . In addition, it is the same as the shoe inner layer material that it is preferable that the single yarn fineness is smaller when used as a nonwoven fabric.

  By using the filter of the present invention, it is possible to suppress static electricity generated by friction with the filter when a flammable liquid or gas is filtered at high speed, and to avoid a flammable explosion. Moreover, since the filtration rate can be set high, it can contribute to productivity improvement.

  Hereinafter, the present invention will be specifically described based on examples. In addition, measurement and evaluation of various physical properties in the following examples were performed by the following methods.

  The conductive performance of the conductive conjugate fiber was cut to a length of 10 cm to make a sample, both ends were bonded to a metal terminal with a conductive adhesive, a DC voltage of 1,000 V was applied, the resistance value was measured, and the value was The specific resistance converted into a group was evaluated.

  The surface resistance of the fabric was measured for conductivity at a parallel electrode width of 7.5 cm and a distance between electrodes of 7.5 cm using a Mega Ohm meter model 800 manufactured by ACL Staticide. For the measurement, a sample conditioned in advance in an environment of 20 ° C. × 30% RH was used.

  The antistatic performance of the fabric was measured in accordance with JIS L 1094 triboelectric charge decay measurement method using an initial charged voltage using a sample conditioned in an environment of 20 ° C. × 30% RH.

  As for durability, washing durability was evaluated. Washing was carried out 100 times by the JIS L 0217 E 103 method, and the conductive performance of the conductive conjugate fiber and the surface resistance of the fabric before and after washing were measured by the above-described methods.

  About the covering ratio of the conductive component on the fiber surface, 20 cross-sectional photographs of the yarn were taken at an arbitrary interval with an Olympus optical microscope, measured with an image analyzer manufactured by Keyence, and evaluated by the average value.

[Examples 1-6, Comparative Examples 1-4]
Conductive polymer in which 25% by weight of conductive carbon black is mixed and dispersed in polyethylene terephthalate copolymerized with 12 mol% of isophthalic acid is used as a conductive component, and homopolyethylene terephthalate is used as a non-conductive component. The composite composites were spun at 285 ° C., and wound at a spinning speed under several conditions while cooling and oiling to produce conductive composite fibers Y1 to Y9. Table 1 shows the conductive performance of Y1 to Y9 and the coating ratio of the conductive component on the fiber surface.

  In Examples 1 to 7 and Comparative Example 1, it was possible to scoop off without any significant problem in spinning, but in Comparative Example 2, the scooped bobbins showed a lot of fluffing, which is not very practical. It was. When the filament resistance was measured, the variation was large and the average value was high.

  Using a polyester long fiber yarn 84 dtex / 72 filament as the warp and weft to form the ground part, we obtained a plain fabric that used Y1 as the conductive yarn and the weft at intervals of 5 mm each, and this fabric was processed by the usual processing method The fabric 1 was processed as 1.

  The same configuration as that of the fabric 1 except that Y2 to Y9 are used as conductive yarns instead of Y1 and polyester continuous fiber yarns 56 decitex / 24 filaments and conductive twisted yarns twisted at 250 T / m are used. Fabrics 2 to 9 were obtained. However, in Y7 where there was a problem in passing through the spinning process, it was judged that there was no practicality because the stoppage was repeated many times in the twisting and weaving processes, and the quality of the fabric 7 was not good. Therefore, it was excluded from the evaluation.

Moreover, the fabric 10 of the structure similar to the fabrics 2-9 was obtained using the conductive fiber Y10 which coat | covered the circumference | surroundings of the nylon monofilament 22 dtex marketed as the comparative example 4 with the carbon black mixing resin. The filament resistance of Y10 was as good as 2.2 × 10 ⁵ Ω / cm · f. Table 2 shows the mixing ratio of conductive fibers and various physical property values in the fabrics 1 to 10.

As is apparent from Table 2, Y5 having a breaking elongation of more than 250% did not give the intended surface resistance measurement result in the present invention. When Y5 was extracted from the fabric 5 and its filament resistance was measured, it was 4.1 × 10 ⁸ Ω / cm · f, and a decrease in conductivity was confirmed after spinning off. It is considered that the film was stretched because tension was applied during the twisting or weaving process.

  In addition, although Y9 having no conductive component exposed on the surface was recognized as having durability against washing, no effect was observed in the surface resistance measurement.

  On the other hand, in Y10, although the performance equal to or higher than that of the present invention was initially exhibited, the conductive component was peeled off and dropped off after 100 washings, and the conductive performance and the antistatic performance were almost lost. On the other hand, in the present invention, good results were obtained in terms of surface resistance and durability.

  Using these fabrics, dustproof garments were produced and evaluated for practical use. As a result, results equivalent to those for the fabrics were obtained.

[Examples 7 to 8, Comparative Example 5]
Conductive polymer in which conductive carbon black is mixed and dispersed in 35% by weight of nylon 6 is used as the conductive component, and nylon 6 is used as the non-conductive component. The mixture was wound at a spinning speed of 900 m / min while cooling and oiling, and stretched at a draw ratio of 1.9 times while heating to produce 330 dtex / 100 filament conductive composite fibers Y11 to Y13. Table 3 shows the conductive performance of Y11 to Y13 and the covering ratio of the conductive component on the fiber surface.

Y11 to Y13 were each converged to about 300,000 dtex, then crimped and cut to a length of 51 mm to obtain a single yarn 3.3 dtex staple.
These staples were mixed with 3.3 dtex and 6 nylon staples of 51 mm length at a blending rate of 5% by weight to produce a nonwoven fabric having a basis weight of about 180 g / m ² by the needle punch method, and further embossed to fabric 11 ~ 13 were obtained. Table 4 shows various physical property values of the fabrics 11 to 13.

As is apparent from Table 4, Comparative Example 5 obtained sufficient effects in antistatic performance and durability, but in the surface resistance measurement, there were many variations in measured values, and a stable effect was not recognized. . It is presumed that the composite ratio of the conductive component is small and the exposure of the conductive component on the fiber surface is insufficient.
In addition, when the non-woven fabric of the present invention is used as a shoe inner layer material and a work shoe with a conductive treatment applied to the sole portion is worn, static electricity accumulated in the human body is leaked through the shoe and the human body voltage is reduced. Results were obtained.

[Examples 9 to 11, Comparative Examples 6 to 7]
A fabric was produced in the same manner as in Example 7 except that the mixing ratio of Y11 was changed. Table 5 shows the physical property values of the obtained nonwoven fabric.

  As is apparent from Table 5, in Examples 9 to 11, as the mixed use ratio of the conductive conjugate fibers increased, the surface resistance and the antistatic performance tended to improve, and all showed satisfactory results. On the other hand, in Comparative Example 6, the mixed use rate was insufficient, and no effect was seen in both surface resistance and antistatic performance. In Comparative Example 7, the surface resistance and the antistatic performance are in a saturated state, and it is considered that the conductive conjugate fiber is excessively present. In particular, there was no problem in process passability and various physical properties as a nonwoven fabric, but the cost was not so good.

Example 12
Embossing was performed on a polyethylene terephthalate long fiber nonwoven fabric obtained by a conventionally known melt blow method to prepare a nonwoven fabric having a basis weight of about 75 g / m ² . To this non-woven fabric, a total of three conductive composite fibers Y2 and polyester long fiber yarn 44 dtex / 18 filaments, S and twisted at 600 T / m, were combined at Z twist of 480 T / m. A non-woven fabric obtained by sewing a twisted sewing thread at intervals of 5 mm in the width direction of the non-woven fabric is designated as fabric 14. The fabric had a surface resistance value of 8.7 × 10 ⁶ Ω and antistatic performance of 2,110 V, and good results were obtained.

  Further, this fabric exhibited sufficient antistatic performance when used as a filter without deterioration in performance even after 100 washes.

  The method of the present invention is particularly suitable for use in clothing worn in a clean room or the like.

It is a cross-sectional view of an example of the electroconductive composite fiber used for the fiber composite of this invention. It is a cross-sectional view of an example of the electroconductive composite fiber used for the fiber composite of this invention. It is a cross-sectional view of an example of the electroconductive composite fiber used for the fiber composite of this invention. It is a cross-sectional view of an example of the conductive composite fiber used for the fiber composite outside the scope of the present invention. It is a cross-sectional view of an example of the conductive composite fiber used for the fiber composite outside the scope of the present invention.

Explanation of symbols

1 Conductive component 2 Non-conductive component

Claims (5)

A fiber composite in which conductive composite fibers composed of a conductive thermoplastic component and a fiber-forming component are mixed, wherein the conductive composite fiber is composed of a thermoplastic polymer containing carbon black. A fiber composite having a composite structure covering 50% or more of the surface, and a melt composite spun conductive composite fiber having a breaking elongation of 80 to 250%. The fiber composite according to claim 1, wherein the conductive composite fiber is contained in an amount of 0.1 to 15% by weight. A dust-proof garment comprising the fiber composite according to claim 1. A shoe inner layer material comprising the fiber composite according to claim 1. A filter comprising the fiber composite according to claim 1.

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