KR101261436B1 - Composite nonwoven fabric comprising Meta Aramid and melt blown fiber and manufacturing thereof - Google Patents

Abstract

The present invention relates to a method for producing a composite nonwoven fabric, which comprises forming a composite nonwoven fabric in a manufacturing process by including meta-aramid fibers having excellent heat resistance and melt blowing which is excellent in the formation of heat, and by using the excellent sound- The present invention relates to a composite nonwoven fabric comprising a meta-aramid fiber and a melt blown yarn, and a method for producing the composite nonwoven fabric. The meta-aramid fiber according to the present invention and the melt blown yarn The composite nonwoven fabric comprising the composite nonwoven fabric may comprise a meta-aramid dope prepared by electrospinning a meta-aramid dope in which the salt concentration is within a range of 1 to 10% by weight based on the total weight of the dope and the meta-aramid is contained within a range of 10 to 30% Including aramid fibers and meltblown yarns Are further characterized in the yirueojim hayeoseo mixing meltblown unsa as the meta-aramid fiber, 5 to 30% by weight and the remaining amount.

Description

TECHNICAL FIELD The present invention relates to a composite nonwoven fabric comprising meta-aramid fibers and melt blown fibers,

The present invention relates to a composite nonwoven fabric comprising a meta-aramid fiber and a melt blown yarn, and a method for producing the composite nonwoven fabric and a method for producing the composite nonwoven fabric. In particular, the present invention includes meta-aramid fibers having excellent heat resistance and melt blown yarns excellent in heat- A composite nonwoven fabric comprising meta-aramid fibers and melt blown fibers capable of having physical properties suitable for applications requiring heat resistance such as separators of fuel cells using the excellent heat resistance of the composite nonwoven fabric obtained therefrom, ≪ / RTI >

Generally, polyamide-based synthetic resins are classified into aliphatic polyamides and aromatic polyamides.

Aliphatic polyamides are generally known under the trade name Nylon, and aromatic polyamides are known under the trade name Aramid.

The aliphatic polyamides, especially nylon 6 and nylon 6,6, are the most common thermoplastic engineering plastics and are used as molding materials in various fields as well as fibers in important applications. The nylon resin used in the molding industry is made of reinforced plastics which is reinforced with mineral or glass fiber to improve mechanical properties such as elasticity and lowering the price to have improved flame retardancy and impact resistance.

Aromatic polyamides, developed in the 1960s, were developed to improve the heat resistance of nylon, an aliphatic polyamide. Aromatic polyamides, known under the trade names Nomex, Kevlar, And has excellent heat resistance and high tensile strength which can be used for textile such as tire cord.

A typical aliphatic polyamide is a synthetic resin having an aliphatic hydrocarbon bonded between amide groups, and an aramid is a synthetic resin having an amide bond having 85% of benzene groups bonded to two aromatic rings between amide groups. The aliphatic hydrocarbon of the aliphatic polyamide easily undergoes molecular motion when heat is applied, whereas the benzene ring of the aromatic polyamide is stable to heat and has a high elastic modulus because the molecular chain is rigid and molecules do not easily move even when heat is applied. And there are many differences in characteristics.

The aromatic polyamide is classified into a para-aramid and a meta-aramid. The para-aramid is represented by Kevlar developed by DuPont. The para-aramid is the benzene ring bound to the amide group at the para position. Since the molecular chain is very stiff and has a linear structure, it has a very high strength and a particularly high elasticity, so that it has excellent shock absorbing performance. It is used for armor, bulletproof helmet, safety gloves, boots and fire extinguisher. It is used for sports equipment such as sticks, fishing rods and golf clubs, and also for industrial use such as FRP (Fiber Reinforced Plastic) and asbestos replacement fibers.

Meta-based aramid, or meta-aramid, is represented by Nomex developed by DuPont and Conex developed by Dejin. The meta-aramid has a merit that the benzene ring is bonded to the amide group at the meta position, and the strength and elongation are similar to ordinary nylon, but the heat stability is very good, and it is light compared to other heat resistant materials, . In the early days, the color was limited to a few, but recently it has been made in various colors including fluorescent colors. It is used as fire-resistant clothing, uniforms for racing motorists, astronaut uniforms, work clothes, etc., and for industrial use, it is used for high-temperature filters.

U.S. Patent No. 3,068,188 discloses a method for producing a meta-aramid by polymerizing m-phenylene diamine (MPD) and isophthaloyl chloride (IPC) in a polar amide solvent, A basic compound was added to neutralize hydrochloric acid to prepare a meta-aramid composition.

On the other hand, nonwoven fabrics made of meta-aramid fibers having excellent heat resistance can be used for various applications, especially separators of secondary batteries due to their excellent heat resistance. This is because the performance of secondary batteries And it is also particularly suitable in that the secondary battery itself can be prevented from malfunctioning and thus the stability of the secondary battery itself can be ensured even when the battery is melted and melted without being burned at a very high temperature . However, the meta-aramid itself is extremely difficult to process into fibers due to the absence of an appropriate solvent, and accordingly, there is a problem in that it is not easy to produce a non-woven fabric made of meta-aramid fibers.

Therefore, there is still a high demand for the development of suitable means for the production of nonwoven fabrics made of meta-aramid fibers.

It is an object of the present invention to provide a nonwoven fabric capable of forming a composite nonwoven fabric in a manufacturing process by including meta-aramid fibers having excellent heat resistance and melt blown yarns having excellent heat-setting properties, and using the excellent heat resistance of the composite nonwoven fabric thus obtained, And a composite nonwoven fabric including a meta-aramid fiber and a melt blown yarn which can have physical properties suitable for applications requiring heat resistance such as a separator.

Another object of the present invention is to provide a method for producing a polymer electrolyte membrane, which comprises melt-kneading an olefin polymer and collecting it on a collector together with meta-aramid fibers formed by electrospinning to form a web, A method for producing a composite nonwoven fabric comprising meta-aramid fibers by allowing the molding of the composite nonwoven fabric to be freely formed in the course of the production of the composite nonwoven fabric by using the heat-bonding property or the thermal property of the melt blown- .

Another object of the present invention is to provide a composite nonwoven fabric comprising meta-aramid fibers and meltblown fibers, in particular, by electrospinning a meta-aramid fiber by controlling the concentration of the dope in the electrospinning of the meta-aramid dope, The present invention is to provide a method for producing a composite nonwoven fabric by simply preparing a composite nonwoven fabric by preparing the composite nonwoven fabric and collecting them together on a collector to form a web.

It is still another object of the present invention to provide a meta-aramid having excellent heat resistance and a melt blown yarn having excellent thermoformability through the production of meta-aramid fibers by electrospinning and the production of melt blown yarns and their bonding on the collector, Aramid fibers and meltblown yarns which can be formed into a desired shape and which can have properties suitable for applications requiring heat resistance such as a separator of a fuel cell by taking advantage of the excellent heat resistance of the composite nonwoven fabric obtained therefrom And a method for producing the composite nonwoven fabric.

It is still another object of the present invention to provide a method for preparing meta-aramid dope, which comprises preparing a meta-aramid dope by adjusting the salt concentration and solid content of the dope without addition of a salt and producing the meta-aramid fiber and the meltblown non- The present invention relates to a composite nonwoven fabric which is capable of forming a composite nonwoven fabric in a manufacturing process by including a meta-aramid having excellent heat resistance and a melt blown yarn excellent in heat formation by collecting the melt blown yarn produced at the same time on a collector, The present invention provides a composite nonwoven fabric comprising meta-aramid fiber and melt blown yarn, which can have physical properties suitable for applications requiring heat resistance, such as a separator of a fuel cell.

The composite nonwoven fabric comprising the meta-aramid fiber and the melt blown yarn according to the present invention has a salt concentration within a range of 1 to 10 wt% based on the total weight of the dope and a meta-aramid content within a range of 10 to 30 wt% And 10 to 15% by weight of the meta-aramid fiber and the remainder of the meta-aramid fiber and the melt blown yarn are mixed.

The melt blown melt may preferably be obtained by meltblowing the olefinic polymer.

The melt blowing may more preferably be obtained by meltblowing polypropylene or polyethylene.

The method for producing the composite nonwoven fabric comprising the meta-aramid fiber and the melt blown yarn according to the present invention is characterized in that in the polymerization process of polymerizing meta-phenylenediamine and isophthaloyl chloride in an amide-based solvent to obtain a reaction product, The neutralization is controlled so as to stop the neutralization reaction when the salt is generated so that the salt concentration is within the range of 1 to 10% by weight based on the total weight of the reaction product by adding a neutralizing agent for neutralizing the HCl, , The concentration of the obtained meta-aramid solids is adjusted to 10 to 30% by weight, and it is irradiated at a spinning temperature of 70 to 100 ° C, a tip-collector distance (TCD) of 4 to 15 cm and a radiation voltage of 10 to 40 kV To produce a meta-aramid fiber; A melt blowing step of melt-blowing the polymer meltable by heat simultaneously with or simultaneously with the meta-aramid production step to produce a melt blown melt; A web forming step of forming a web by collecting and focusing the meta-aramid fiber produced in the meta-aramid manufacturing step and the melt blown melt obtained in the melt blown manufacturing step on a collector; And forming a nonwoven fabric by heating and pressing the web obtained in the web forming step to form a nonwoven fabric.

The salt concentration of the meta-aramid dope in the step of preparing the meta-aramid may be preferably 7 to 8% by weight.

The solid content concentration of the meta-aramid dope in the step of preparing the meta-aramid may preferably be 10 to 25% by weight.

According to the present invention, there is provided a method for preparing a meta-aramid nonwoven fabric suitable for use by controlling the diameter of electrospun meta-aramid fiber by controlling the concentration of the dope in the electrospinning of the meta-aramid dope for producing the meta-aramid nonwoven fabric, A meta-aramid nonwoven fabric and a method for producing the same.

According to the present invention, it is possible to produce various types of meta-aramid nonwoven fabrics according to applications by preparing meta-aramid fibers having various diameters by variously changing the conditions of electrospinning, and a method for producing the meta-aramid non- An aramid nonwoven fabric and a method for producing the same.

According to the present invention, the meta-aramid dope is prepared by controlling the salt concentration and the solid content of the dope and the degree of disorder and diameter of the meta-aramid fiber obtained by electrospinning the meta- An aramid nonwoven fabric and a method for producing the same.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

The terms " about "," substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation of, or approximation to, the numerical values of manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

A typical meta-aramid is polymerized by reacting metaphenylenediamine and isophthaloyl chloride as starting materials according to Reaction Scheme 1 below.

[Reaction Scheme 1]

As described above, the metaphenylenediamine and the isophthaloyl chloride are polymerized in the polar amide solvent as shown in the reaction scheme 1 to produce polymethaphenylene isophthalate (meta-aramid). At this time, the isophthaloyl chloride may be added to the polar amide-based solvent containing the metaphenylenediamine to improve the reactivity through exothermic reaction control.

When the poly (meta-phenylene isophthaloyl chloride) is produced by reacting metaphenylenediamine with isopthaloyl chloride as described above, hydrochloric acid is produced as a by-product, and for the stability of the obtained polymer composition, hydrochloric acid as the by- .

In order to neutralize hydrochloric acid produced by the reaction of metaphenylenediamine with isophthaloyl chloride, a basic compound such as calcium hydroxide (Ca (OH) ₂ ) or lithium hydroxide (LiOH) is added as a neutralizing agent, and calcium hydroxide, Can be represented as shown in Reaction Scheme 2 below.

[Reaction Scheme 2]

2HCl + Ca (OH) _{2 -} > CaCl ₂ + 2H ₂ O

HCl + LiOH → LiCl + H ₂ O

The composite nonwoven fabric comprising the meta-aramid fiber and the melt blown yarn according to the present invention has a salt concentration within a range of 1 to 10 wt% based on the total weight of the dope and a meta-aramid content within a range of 10 to 30 wt% And 10 to 15% by weight of the meta-aramid fiber and the remainder of the meta-aramid fiber and the melt blown yarn are mixed.

The production of meta-aramid fibers by electrospinning used in the production of the composite nonwoven fabric according to the present invention is as follows.

According to the present invention, it is possible to manufacture a nonwoven fabric by preparing a fiber by electrospinning of a meta-aramid, and then collecting the same to manufacture a nonwoven fabric. A meltblown fabric is produced at the same time or at the same time, Can be collected on a collector to form a web at the same time as the mixing thereof, thereby producing a composite nonwoven fabric.

Among the composite nonwoven fabrics, the meta-aramid fibers may be used in an amount of 5 to 30 wt% based on the total weight of the composite nonwoven fabric, and when the meta-aramid fibers are used in an amount of less than 5 wt% There may be a problem that the composite nonwoven fabric such as heat resistance and mechanical strength has insufficient physical properties to be possessed by fibers, and on the contrary, if it exceeds 30 wt%, the composite nonwoven fabric may have no particular problem in its physical properties, If the content of the aramid fiber is too high, the content of the melt blown yarn becomes too small to reduce the thermal formation and / or thermal adhesiveness of the resultant composite nonwoven fabric, and the production cost due to the high content of expensive meta-aramid fibers There is a problem of improvement.

The salt concentration of the meta-aramid dope may be in the range of 1 to 10% by weight based on the total weight of the reaction product and may be less than 1% by weight, or in the case of exceeding 10% by weight, There is a problem that it is difficult to form the web.

When the content of the meta-aramid solids in the meta-aramid dope is less than 10% by weight, there may be a problem of spraying due to electrical dispersion rather than production of fibers by electrospinning, On the other hand, if it exceeds 30 wt%, the surface tension and the solution viscosity become too high, so that the electric field force overcomes the surface tension of the solution and may cause a problem of instability in the spinning have.

The melt blowing may preferably be obtained by meltblowing the olefin-based polymer, but the present invention is not limited to the olefin-based polymer. The meltblown process for obtaining the meltblown of the olefinic polymer is a process in which a polymer as a raw material for meltblown is melted and is radiated as a fiber using a high temperature and high pressure air stream. The nonwoven fabric is made of a structure such as a spider web in which extremely fine melt blown yarns are combined and is used for various filters, masks, sanitary products, clothing products, wipers, separators for batteries It will be readily understood by those skilled in the art.

The above-mentioned melt blowing may more preferably be obtained by melt blowing polypropylene or polyethylene, but the present invention is not limited thereto. Melting blown materials such as polypropylene or polyethylene as described above are partially melted due to heating due to the specific thermoplasticity of the olefin-based polymer and exhibit melt-bonding property. Therefore, the web including the meltdown of these olefin- In the case of the present invention, it can be fused to the above-mentioned meta-aramid fibers, and the resulting composite nonwoven fabric can exhibit mechanical workability, in particular, thermoformability, and melt Due to the extremely fine structure of the blown yarn itself, it is possible to simultaneously exhibit physical properties that the nonwoven fabric must possess such as filtering, sound absorption, sound insulation, heat insulation, and moisture absorption.

The method for producing a composite nonwoven fabric comprising a meta-aramid fiber and a melt blown yarn according to the present invention is characterized in that it is produced as a by-product in a polymerization process of polymerizing meta-phenylenediamine and isophthaloyl chloride in an amide- The neutralization is controlled so as to stop the neutralization reaction when the salt is generated so that the salt concentration is within the range of 1 to 10 wt% based on the total weight of the reaction product, The dope is prepared by adjusting the solid content of the obtained meta-aramid to 10 to 30 wt%, irradiating it with a radiation temperature of 70 to 100 DEG C, a tip-collector distance (TCD) of 4 to 15 cm, A step of producing meta-aramid fibers by electrospinning at a radiation condition of 40 kV to produce meta-aramid fibers; A melt blowing step of melt-blowing the polymer meltable by heat simultaneously with or simultaneously with the meta-aramid production step to produce a melt blown melt; A web forming step of forming a web by collecting and focusing the meta-aramid fiber produced in the meta-aramid manufacturing step and the melt blown melt obtained in the melt blown manufacturing step on a collector; And forming a nonwoven fabric by heating and pressing the web obtained in the web forming step to form a nonwoven fabric.

Here, the production of the meta-aramid fiber by electrospinning is carried out in the presence of a neutralizing agent for neutralizing hydrochloric acid (HCl) produced as a by-product in the polymerization process of polymerizing meta-phenylenediamine and isophthaloyl chloride in an amide- The neutralization is controlled so as to stop the neutralization reaction when the salt is generated so that the salt concentration is within the range of 1 to 10 wt% based on the total weight of the reaction product, thereby preparing the meta-aramid dope. The concentration was adjusted to 10 to 30 wt% and electrospun was radiated at a spinning temperature of 70 to 100 DEG C, 4 to 15 cm of tip-to-collector distance (TCD) and a radiation voltage of 10 to 40 kV, Aramid fibers. That is, in the step of preparing the meta-aramid, a neutralizing agent for neutralizing hydrochloric acid (HCl) produced as a by-product in a polymerization process of polymerizing metaphenylenediamine and isophthaloyl chloride in an amide-based solvent to obtain a reaction product is added, And controlling the neutralization so as to stop the neutralization reaction when the salt is generated so that the salt concentration is within the range of 1 to 10 wt% based on the total weight of the reaction product. More specifically, the step of preparing the meta-aramid comprises: a polymerization step of preparing a reaction mixture by adding metaphenylenediamine and isophthaloyl chloride to an amide-based solvent, and polymerizing the resulting mixture to obtain a reaction product; A neutralization step of adding a neutralizing agent for neutralizing hydrochloric acid (HCl) produced as a by-product; And a post-treatment step of performing dehydration and defoaming after the neutralization step, wherein the neutralization step is a step of dehydration and deaeration of the reaction product, And a neutralization control step of controlling neutralization so as to stop the neutralization reaction when the neutralization reaction is carried out. In the above-mentioned polymerization process, the reaction mixture is prepared by adding metaphenylenediamine and isophthaloyl chloride to an amide-based solvent and polymerization is carried out to obtain a reaction product.

The polymerization step is preferably a step of forming a poly (meta phenylene isophthalamide) by a reaction of mixing and stirring meta-phenylenediamine and isophthaloyl chloride in an amide-based solvent, The phenylenediamine and isophthaloyl chloride are preferably reacted at a similar molar ratio. In terms of weight, 5 to 12 parts by weight of the metaphenylenediamine and 9 to 25 parts by weight of the isophthaloyl chloride are mixed and polymerized based on 100 parts by weight of the amide solvent. The amide-based solvent is preferably a polar amide-based solvent, and it is preferable to use dimethylacetamide or N-methyl-pyrrolidone. The neutralization process is performed by adding a neutralizing agent to neutralize hydrochloric acid (HCl) generated as a by-product in the polymerization process. The neutralization process in the conventional method for producing meta-aramid is a process of adding calcium hydroxide as a neutralizing agent to neutralize hydrochloric acid, which is a byproduct of the polymerization process. The amount to be added is controlled according to the amount of metaphenylenediamine or isophthaloyl chloride used, Is added in an amount equal to or about 10% of the molar ratio of the metaphenylenediamine or isophthaloyl chloride. However, the neutralization process in the present invention includes a neutralization control step of controlling the neutralization so that the neutralization reaction is stopped when the salt is generated so that the salt concentration is within the range of 1 to 10 wt% based on the total weight of the reaction product . The neutralization control step controls the salt concentration contained in the reaction product, and thus it is possible to directly produce meta-aramid dope suitable for electrospinning in the course of synthesis of meta-aramid.

According to the conventional method for preparing a meta-aramid dope which does not have such a neutralization control step, it is necessary to carry out a calcium chloride addition process in which calcium chloride (CaCl ₂ ) is added after the neutralization reaction as described above. Is a step of additionally adding calcium chloride. However, since the amount of calcium chloride generated in the neutralization step can not provide an appropriate salt concentration for dissolution of meta-aramid suitable for electrospinning, calcium chloride A process for further adding a salt of an alkali metal salt is required. The radiation processability and web formation of electrospinning are influenced by many factors such as the concentration of the dope, the viscosity of the solution, the surface tension and the electrical conductivity, and therefore, the conventional method of producing the meta-aramid In the case of meta-aramid, there is a disadvantage that it is difficult to obtain an optimal electrodeposited meta-aramid dope without addition of a salt because the amount of calcium chloride generated in the neutralization process provides theoretically and practically fixed values. For example, when the intrinsic viscosity (IV) of the polymer is 1.6, the salt concentration may be 7.6%.

In the preparation of the meta-aramid dope according to the present invention, the salt concentration obtained by the neutralization step, particularly preferably, when calcium hydroxide is added as a neutralizing agent, the concentration of calcium chloride as the salt is preferably 1 By weight to 10% by weight, the neutralization is controlled so that the neutralization reaction is stopped. The salt, especially calcium chloride, increases the solubility of the meta-aramid, which is a polymer in the solvent, to increase the content of the meta-aramid solids. When the content of the calcium chloride is less than 1% by weight of the meta-aramid composition, there is a problem that the increase of the solid content becomes insignificant and becomes unsuitable for electrospinning. On the contrary, when it exceeds 10% by weight, There is a problem that workability is lowered.

After the neutralization step, a post-treatment step in which dehydration and defoaming are carried out in the same or similar manner as in the production of conventional meta-aramid can be further performed. Such post-treatment steps, particularly dehydration and defoaming, You can.

Particularly, the dewatering process is a process for removing water (H ₂ O) generated in the neutralization process, and the defoaming process is a process for removing bubbles generated by stirring in a polymerization process, and can be performed by a general dehydration and defoaming process. The defoaming process may be carried out usually under reduced pressure or under vacuum.

According to the method for preparing an electrodeposition meta-aramid dope as described above, an electrodeposited meta-aramid dope in which the solid content of the meta-aramid is in the range of 10 to 30% by weight is obtained. When the content of the meta-aramid solids in the meta-aramid dope according to the present invention is less than 10% by weight, there may arise a problem of spraying due to electrical dispersion rather than production of fibers by electrospinning, If the concentration exceeds 30 wt%, the surface tension and the solution viscosity become too high, so that the electric field force overcomes the surface tension of the solution and causes instability in the spinning. There is a problem, and in addition, the concentration of the salt is also less than a certain amount, which makes it impossible to control, and excessive dilution is required, which raises the manufacturing cost. Particularly, according to the present invention, neutralization is controlled so that the salt is generated so that the salt concentration is within a range of 1 to 10% by weight based on the total weight of the reaction product during the production of the meta-aramid, Since the control step is included, it is possible to control the salt concentration in the entire dope as well as to freely control the amount of the meta-aramid solid in the dope. The salinity is an important factor for determining the radioactivity of producing fibers from meta-aramid dope in the form of solution in electrospinning. The lower the salinity, the higher the straightness of the web obtained by electrospinning and the higher the salinity And the tendency that the straightness of the web is lowered becomes higher. However, if the salt concentration is too low or too high, the electrospinning itself may not be performed well and the formation of the web may become virtually impossible.

As is well known, electrospinning is a modification of the electrostatic spray process in which fine filaments are released from the surface of a droplet when a high voltage is applied to the droplet suspended at the end of the capillary due to the surface tension. The viscosity of the polymer solution or melt It is a phenomenon that fibers are formed when they are received. Therefore, in order to induce an electrostatic force in the polymer solution, it is necessary to include a salt in order to have electrical characteristics in the polymer solution that has been spun.

In conventional fiber spinning techniques, the polymeric melt or polymer solution is extruded and extruded through a spinning nozzle using mechanical forces, while electrostatic forces are used in charge-induced spinning. That is, when a high voltage electric field is applied to the polymer droplet droplet suspended from the tip of the spinning nozzle by the surface tension, the charge is induced on the liquid surface, and the force due to the mutual repulsive force of the induced charge is generated in the direction opposite to the surface tension. The fine droplets of the polymer solution suspended from the tip of the spinning nozzle by such an electric repulsive force are attracted by the Taylor cone (the positively charged polymer solution is drawn from the spinneret to the collector by the electric field, The jet flow of the solution is formed and the jet flow is in the form of a cone and is thus transformed into a Taylor cone), and when the electric repulsive force becomes stronger than the surface tension, the charged polymer solution jet is ejected from the spinning nozzle . In this polymer solution jet, while the air is blown, the solvent is volatilized and only the charged continuous fibers are deposited on the collector in the form of a web.

Thus, the working principle of electrospinning can directly affect the spinnability of the polymer solution, i.e., the salt concentration, the solid concentration and the intrinsic viscosity, of the dope, both directly to the emission of the dope to the fiber, Diameter, length, and the like, and if these variables are out of the predetermined range, the radiation may not be produced at all.

The salt concentration of the meta-aramid dope may be in the range of 1 to 10% by weight based on the total weight of the reaction product and may be less than 1% by weight, or in the case of exceeding 10% by weight, There is a problem that it is difficult to form the web.

The solid concentration control step comprises diluting the concentration of the meta-aramid obtained in the step of preparing the meta-aramid to 10 to 30% by weight.

The electrospinning step comprises electrospinning the meta-aramid doped as described above under spinning conditions at a spinning temperature of 70 to 100 ° C, a spinning distance of 4 to 15 cm and a spinning voltage of 10 to 40 kV. The above-mentioned spinning conditions are optimized for electrospinning of the meta-aramid doped as described above, i.e. the meta-aramid dope composed of a salt concentration in the range of 1 to 10% and a solid concentration of 10 to 30% by weight The conditions that can be used are selected by experimental methods.

When the spinning temperature is lower than 70 캜, the solution viscosity is too high, so that a high voltage is required for spinning, and the amount of spinning to the discharge amount is reduced, so that the Taylor cone becomes large and solidification occurs, In contrast, when the temperature exceeds 100 ° C, there is a problem that the solution viscosity changes due to the evaporation of water present in the dope, making it difficult to ensure uniform radioactivity.

When the radiating distance is less than 4 cm, There is a problem that the solvent is not completely volatilized by the solvent so that the fiber formation is not performed. On the other hand, if it exceeds 15 cm, the electric field is weakened and the spun fiber can not be focused on the collector .

The meta-aramid fibers obtained as described above are collected in a collector, and are then collected on a collector together with meltblown olefin polymer produced at the same time or at the same time, and the meta-aramid fibers are mixed with the meltblown web . Thereafter, the web is heated and pressed at a temperature close to the melting point of the melt blown yarn to melt the meltblown yarn and melt bind the meltblown yarn using the meltblown yarn, Aramid fibers to form the composite nonwoven fabric intended by the present invention. At this time, physical force is applied to the resultant composite nonwoven fabric, thereby thermoforming the nonwoven fabric into a desired shape.

The phrase " simultaneous " in the phrase " simultaneously or externally generated " as used herein means that both the process of producing the meltdown and the process of producing the meta-aramid fiber are simultaneously carried out, Means to form a web for the production of a nonwoven fabric. The term " ish " means that the process for producing the meltdown and the process for producing the meta-aramid fiber are performed at different times, And / or the meta-aramid fibers are first produced, and the other meta-aramid fibers or melt blown fabrics, which have been prefabricated during the manufacturing process of any of these meltblown yarns or meta-aramid fibers, To form a web for the production of a nonwoven fabric. That is, it is possible to mix the melted blown yarn in the process of forming and supplying the already finished meta aramid fiber during the manufacturing process of the melt blown yarn, or to make the melted blown yarn already completed during the manufacturing process of the meta-aramid fiber, And can be mixed with the meta-aramid fibers in the process of being formed by supplying.

Although the foregoing description has been made by heating and pressing in forming the web into a composite nonwoven fabric, the present invention is not limited thereto, and other known methods for producing nonwoven fabrics may be used, and these will be easily understood by those skilled in the art You can.

The heating and pressing conditions include heating and pressing at a temperature within a range of 100 to 200 DEG C and under a line pressure within a range of 10 to 200 kg / cm. It will be understood by those skilled in the art that this can be performed by heating pressing by a so-called calendering method. When the temperature is lower than 100 ° C, the olefin-based fibers can not be sufficiently bonded and it is difficult to obtain a desired nonwoven fabric. At a temperature of 200 ° C or higher, olefin-based fibers are over-melted and the characteristics of the nonwoven fabric are not easily developed.

Hereinafter, embodiments of the composite nonwoven fabric including the meta-aramid fiber and the melt blown yarn according to the present invention will be described, but the present invention is not limited thereto.

Example

1404 g of methyphenylene diamine and 2639 g of isophthaloyl chloride were mixed and polymerized to carry out a polymerization process. After the above polymerization process, 7 parts by weight of calcium hydroxide as a neutralizing agent for neutralization of hydrochloric acid produced as a byproduct of the reaction was added Neutralization is carried out to remove the unreacted neutralizing agent remaining in the neutralized agent introduced into the reaction product when the salt concentration in the meta-aramid dope as the reaction product becomes 7.0% by weight based on the total weight of the meta-aramid dope, The reaction was stopped. Thereafter, dehydration and defoaming processes were carried out to prepare an electrodeposited meta-aramid dope having a solid content of 13 wt% and IV 1.75 according to the present invention, and a radiation temperature of about 90 ° C, a radiation distance of about 7 cm, and a radiation voltage of about 15 kV To obtain a web composed of meta-aramid fibers, and at the same time, using a known melt blowing process using polypropylene, a melt blowing process comprising a polypropylene is produced together with the meta-aramid fibers, The fibers and the melt blown yarn were collected on a common collector to obtain a web. The mixing ratio of the meta-aramid fiber and the melt blown yarn was 13% by weight: 87% by weight of the meta-aramid fiber: melt blown yarn So that the mixing ratio was adjusted as much as possible.

The resultant web was heated under a linear pressure of 50 kg / cm at a temperature of 150 ° C to obtain a composite nonwoven fabric according to the present invention.

It was confirmed that the composite nonwoven fabric obtained was molded so as to satisfy the requirements of a predetermined standard without appearance defect in the molding of the heat-resistant sound-absorbing material, and sufficient sound-absorbing property and heat-resistance property in the engine room where high temperature was generated can do.

The present invention can be used in an industry for producing composite nonwoven fabrics containing meta-aramid fibers and melt blown fabrics. Such composite nonwoven fabrics can also be used as heat-absorbing materials for automobiles and the like, .

Claims (7)

A meta-aramid dope is produced by electrospinning a meta-aramid dope with a salt concentration within a range of 1 to 10 wt% and a meta-aramid content within a range of 10 to 30 wt% as a solid content based on the total weight of the meta- Wherein the meta-aramid fibers are melt blended with 5 to 30% by weight of the meta-aramid fibers and the remaining amount of the meta-aramid fibers and the melt blown yarns. The method according to claim 1,
Wherein the melt blown yarn is obtained by meltblowing the olefinic polymer. The composite nonwoven fabric according to claim 1, wherein the meltblown yarn is meltblown. 3. The method of claim 2,
Characterized in that the melt blown yarn is obtained by meltblowing polypropylene or polyethylene. The composite nonwoven fabric according to claim 1, wherein the meltblown yarn is meltblown. A neutralizing agent for neutralizing hydrochloric acid (HCl) produced as a by-product in the polymerization process of polymerizing meta-phenylenediamine and isophthaloyl chloride in an amide-based solvent to obtain a reaction product is added, and a salt concentration Is adjusted to be within a range of 1 to 10% by weight, the neutralization is controlled so as to stop the neutralization reaction, and the concentration of the solid content of the obtained meta-aramid is adjusted to 10 to 30% by weight, Preparing a meta-aramid fiber by electrospinning at a temperature of 70 to 100 DEG C, a tip-to-collector distance (TCD) of 4 to 15 cm, and a radiation voltage of 10 to 40 kV;
A melt blowing step of melt-blowing the polymer meltable by heat simultaneously with or simultaneously with the meta-aramid production step to produce a melt blown melt;
A web forming step of forming a web by collecting and focusing the meta-aramid fiber produced in the meta-aramid manufacturing step and the melt blown melt obtained in the melt blown manufacturing step on a collector; And
Forming a nonwoven fabric by heating and pressing the web obtained in the web forming step to produce a nonwoven fabric;
Wherein the composite nonwoven fabric comprises a meta-aramid fiber and a melt blown yarn. 5. The method of claim 4,
Wherein the salt concentration of the meta-aramid dope in the step of preparing the meta-aramid is in the range of 7 to 8 wt%. 5. The method of claim 4,
Wherein the concentration of the solid content of the meta-aramid dope in the step of preparing the meta-aramid is in the range of 10 to 25% by weight. delete