KR102525136B1 - Excellent crimp aramid conjugated fiber and Non-woven fabric comprising the same - Google Patents

Abstract

The present invention is a first resin comprising a meta-aramid polymer; And a second resin comprising a polyethylene terephthalate (PET) copolymer; it relates to a composite fiber prepared by conjugate spinning, wherein the second resin is soluble in an amide-based solvent, characterized in that it has excellent bulkiness and crimpability It relates to an aramid composite fiber, and a nonwoven fabric having excellent elastic recovery including the same.

Description

Aramid conjugated fiber with excellent crimpability and non-woven fabric containing the same {Excellent crimp aramid conjugated fiber and Non-woven fabric comprising the same}

The present invention relates to an aramid composite fiber having excellent crimpability by conjugate spinning of a polyethylene terephthalate resin and a meta-aramid resin dissolved in an amide-based solvent, and to a nonwoven fabric including the same.

Polyamide-based synthetic resins are generally classified into aliphatic polyamides and aromatic polyamides. Aliphatic polyamides are generally known under the trade name nylon, and aromatic polyamides under the trade name aramid. The above aliphatic polyamide. In particular, 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 for important applications. Nylon resins used in the molding field are reinforced with minerals or glass fibers to make reinforced plastics, which are composite materials, in order to have improved flame retardancy and impact resistance, lower prices, and improve mechanical properties such as elastic modulus.

Aromatic polyamide, or aramid resin, has a rigid molecular chain due to the presence of a benzene ring and does not move easily even when heated, so it does not melt by heat and starts to decompose immediately. shows a lot of difference in

On the other hand, in producing fibers with crimping performance, a method of individually spinning one polymer to vary the quenching speed for each part and a method of composite spinning by selecting two different polymers have been proposed. there is. The method of manufacturing crimped yarn by double cooling lacks crimping performance compared to the conjugate spinning method of two polymers, and there are many facility restrictions in equipping large-scale production facilities. Currently, the method of conjugate spinning of two polymers is Most commonly commercialized.

The crimped fibers that have been studied recently are made by combining two polymers with different heat shrinkability into side-by-side or sheath-core, and then applying heat in the spinning or drawing process. It is a fiber that has a physical coil shape due to the difference in heat shrinkage and has been given high elasticity and bulkiness with a principle similar to that of a spring. Although it does not reach conventional spandex fibers in elasticity, it is a differentiated fiber that is actively researched because it has excellent chlorine resistance and shape stability, which are disadvantages of the spandex fiber, as well as easy dyeing and post-processing.

Meta-aramid fibers can be used as the material of the crimped yarn. For example, in Korean Patent Publication No. 2019-0000541, meta-aramid fibers were produced by spinning meta-aramid resin alone. However, when the meta-aramid resin is used as one of the composite fibers, high heat resistance and high strength must be satisfied by applying the solution spinning method, so it is difficult to use it by composite spinning in combination with other types of polymers. In addition, the same existing meta-aramid composite fiber had a difficult problem in realizing various desired physical properties such as bulkiness and shrinkage.

Republic of Korea Patent Publication No. 2019-0000541 (published date: 2019.01.03)

It was devised to solve the above problems, a first resin containing a meta-aramid polymer; And a second resin dissolved in an amide-based solvent can be conjugated to produce composite fibers, and conjugate fibers with improved crimpability and bulkiness can be produced due to the difference in thermal contraction rates between the first resin and the second resin. Including this, it is possible to manufacture a nonwoven fabric with improved elastic recovery.

The aramid composite fiber having excellent crimpability of the present invention includes a first resin containing a meta-aramid polymer; It may be a composite fiber comprising a; and a second resin comprising a polyethylene terephthalate copolymer.

In a preferred embodiment of the present invention, the composite fiber may have a heat shrinkage rate of 25,000 to 50,000 ppm measured by the ASTM-E881 method.

In a preferred embodiment of the present invention, the number of crimps (crimp number) per inch of the conjugate fiber may be 17 to 30.

In a preferred embodiment of the present invention, the first resin may include a polymer copolymerized with aromatic diamine and aromatic diacid chloride.

In a preferred embodiment of the present invention, the second resin may have a glass transition temperature of 70 to 150 °C.

In a preferred embodiment of the present invention, the second resin may be dissolved in an amide-based solvent.

In a preferred embodiment of the present invention, the amide-based solvent is at least one selected from dimethyl acetamide, hexamethylphosphoramide, N-methylpyrrolidone, tetrahydrofuran, hexafluoroisopropanol and dimethyl sulfoxide. can include

In a preferred embodiment of the present invention, the cross-sectional area ratio of the first resin and the second resin in the composite fiber may be 1:0.25 to 1:4.0.

In a preferred embodiment of the present invention, the cross section of the composite fiber may be a side-by-side type composite fiber or a core-sheath type composite fiber.

In a preferred embodiment of the present invention, the core-sheath type conjugate fibers include a core portion comprising a polyethylene terephthalate copolymer; and a sheath portion comprising a meta-aramid polymer.

In a preferred embodiment of the present invention, the difference in heat shrinkage rate between the first resin and the second resin may be 10,000 to 20,000 ppm.

In a preferred embodiment of the present invention, the conjugate fiber may have a single yarn fineness of 0.5 to 5.0 denier.

For another purpose of the present invention, a nonwoven fabric may be prepared by including 5 to 80 parts by weight of the composite fiber.

The present invention is a meta-aramid resin that was difficult to spin in combination with other types of polymers; And a polyethylene terephthalate copolymer resin dissolved in an amide-based solvent can be conjugated in a side-by-side or core-sheath type to produce an aramid composite fiber with excellent bulkiness and crimpability, and the elastic recovery ability is improved by including the composite fiber non-woven fabrics can be produced.

1 is a cross-sectional view of an aramid composite fiber according to an embodiment of the present invention, and is a schematic diagram of side-by-side and sheath-core composite fibers.

Hereinafter, the present invention will be described in more detail through the manufacturing method of the aramid composite fiber having excellent crimpability of the present invention.

The method for producing an aramid composite fiber having excellent crimpability includes a first step of dissolving a first resin and a second resin in an amide-based solvent to prepare a first spinning agent solution and a second spinning agent solution; a second step of obtaining a spinning material by complex spinning the first spinning bath liquid and the second spinning bath liquid; a third step of pre-conditioning and conditioning the radiation; and a fourth step of obtaining a composite fiber by stretching and heat-treating the spun material having performed the third step.

Specifically, the step of polymerizing the first resin of the first step; And performing a neutralization process; it can be prepared, including.

First, the polymerization reaction may include preparing a polymer by copolymerizing aromatic diamine and aromatic diacid chloride through a reaction as in Scheme 1 below, and preferably, the aromatic diamine may include metaphenylenediamine, , The aromatic diacid chloride may include isophthaloyl chloride.

[Scheme 1]

Through the polymerization reaction of Scheme 1, metaphenylenediamine and isophthalyl chloride may be stirred in an amide-based solvent to form poly-metaphenyleneisophthalamide, which is one of the meta-aramid polymers, through a polymerization reaction.

In addition, it is preferable to react the metaphenylenediamine and isophthaloyl chloride in a similar molar ratio, more preferably 5 to 15 parts by weight of metaphenylenediamine and 10 to 10 parts by weight of isophthaloyl chloride to 100 parts by weight of the amide solvent. Polymerization may be performed by mixing 30 parts by weight, and more preferably, 8 to 12 parts by weight of metaphenylenediamine and 15 to 25 parts by weight of isophthaloyl chloride are mixed with 100 parts by weight of the amide-based solvent. In addition, the amide-based solvent uses a polar amide-based solvent, and at least one selected from dimethyl acetamide, hexamethylphosphoramide, N-methylpyrrolidone, tetrahydrofuran, hexafluoroisopropanol, and dimethyl sulfoxide can be used, including

In addition, the polymerization reaction can be carried out at 0 ~ 70 ℃, preferably can be carried out at 10 ~ 60 ℃. If polymerization is carried out at a temperature outside the above range, there may be problems in that the molecular weight distribution of the polymer is lowered due to a decrease in polymerization degree due to modification of metaphenylenediamine and occurrence of side reactions.

In addition, the meta-aramid polymer is poly(meta phenylene isophthalamide), poly(m-benzamide), poly(m-phenylene isophthalamide), poly(m,m'-phenylene benzamide) and poly (1,6-naphthylene isophthalamide), preferably poly(meta phenylene isophthalamide), poly(m-benzamide) and poly(1,6-naphthylene isophthalamide). amide), and more preferably poly(meta phenylene isophthalamide).

Subsequently, in the neutralization process, metaphenylenediamine and isophthaloyl chloride react to neutralize hydrochloric acid (HCl), which is a by-product of polymerized meta-phenylene isophthalamide, and through the neutralization step, the stability of the meta-aramid polymer this can be improved.

Specifically, the neutralization process may be performed by adding a basic compound such as calcium hydroxide (Ca(OH) ₂ ) or lithium hydroxide (LiOH). A preferred example of the neutralization process is described in detail through Reaction Scheme 2 below.

[Scheme 2]

HCl + Ca(OH) ₂ → CaCl ₂ +2H ₂ O

The neutralization process shown in Reaction Scheme 2 is a process of adding a basic compound to neutralize hydrochloric acid, a by-product of the polymerization reaction, and the amount of the basic compound depends on the amount of metaphenylenediamine or isophthaloyl chloride used in the polymerization reaction. It should be adjusted, and it may be desirable to add 5 to 15 mol%, preferably 7 to 13 mol% more than the same as the molar ratio of metaphenylenediamine or isophthaloyl chloride used.

Apart from this, the second resin may include a polyester resin, preferably a polyethylene terephthalate (PET) copolymer, and the polyester resin is esterified by an esterification reaction between an acid and a diol component. preparing a product; preparing a polycondensation reaction product by mixing the ester reaction product with a titanium-based catalyst; and preparing a polyester resin by subjecting the polycondensation reactant to a polycondensation reaction.

In this case, the esterification reaction may be performed by reacting an esterification reaction product containing an acid component and a diol component in a molar ratio of 1: 1.2 to 2.0, preferably 1: 1.2 to 1.5.

Specifically, the esterification reaction may be carried out at a temperature of 200 to 270 °C, preferably at a temperature of 210 to 260 °C and a pressure of 1100 to 1350 Torr, preferably 1120 to 1330 Torr. If the above conditions are not satisfied, there may be a problem in that an esterification compound suitable for a polymerization/condensation reaction cannot be formed due to an increase in esterification reaction time or a decrease in reactivity.

The acid component may include at least one selected from terephthalic acid and isophthalic acid, preferably at least two selected from terephthalic acid and isophthalic acid.

If, as a preferred example, in the case of using both terephthalic acid and isophthalic acid, the isophthalic acid may contain 20 to 40 mol%, preferably 25 to 35 mol% of the acid component. If isophthalic acid is less than 20 mol% in the acid component, there may be a problem that it is not well dissolved in the amide-based solvent, and if it exceeds 40 mol%, the glass transition temperature may be excessively lowered, resulting in a problem of deterioration in heat resistance. In addition, terephthalic acid may be included in an acid component in a residual amount excluding the isophthalic acid.

Meanwhile, the diol component may include at least one selected from ethylene glycol and neopentyl glycol, preferably at least two selected from ethylene glycol and neopentyl glycol.

If, as a preferred example, when both ethylene glycol and neopentyl glycol are used, the neopentyl glycol may be included in 40 to 60 mol%, preferably 45 to 55 mol%, of the diol component. If the neopentyl glycol is included in less than 40 mol% based on the diol component, there is a concern that the solubility characteristics in amide-based solvents may be reduced and the use may be limited. In this case, the glass transition temperature may be excessively lowered, resulting in a decrease in heat resistance. In addition, the ethylene glycol may be included in a residual amount of the diol component except for the neopentyl glycol.

Next, the titanium-based catalyst is a catalyst typically used in polymerization/condensation of co-polyester, preferably a titanium-based polymerization catalyst, and more specifically, a titanium chelate polymerization catalyst. Since the titanium chelate polymerization catalyst is stable even in the presence of water molecules, it does not lose activity even when added before the esterification reaction in which a large amount of water is produced as a by-product, so that the esterification reaction and the polycondensation reaction proceed in a shorter time than before. can The titanium chelate polymerization catalyst of the present invention may be one of titanium citrate chelate, titanium lactic acid chelate and titanium maleic acid chelate. The titanium-based catalyst may be included in an amount of 200 to 500 ppm, preferably 250 to 450 ppm, based on the total weight of the first resin. As the content of the titanium-based catalyst in the prepared PET copolymer increases, the effect of better thermal stability or color tone of the PET copolymer can be seen. If provided in less than 200ppm, it may be difficult to adequately promote the esterification reaction, and if provided in excess of 500ppm, reactivity may be promoted, but there may be a problem in that coloring occurs.

Next, the polycondensation reaction may be performed at a temperature of 250 to 300 °C and a pressure of 0.3 to 1.0 Torr, preferably at a temperature of 260 to 290 °C and a pressure of 0.5 to 1.0 Torr. If the above conditions are not satisfied, there may be problems such as delay in reaction time, decrease in polymerization degree, and induction of thermal decomposition.

The second resin prepared by the above method may have a weight average molecular weight of 30,000 to 100,000, preferably 40,000 to 60,000. If the weight average molecular weight is less than 30,000, there may be a problem in processability due to low viscosity of the solution, and if the weight average molecular weight exceeds 100,000, gelation may occur when dissolved in an amide solvent.

In addition, the second resin may have a glass transition temperature of 70.0 to 150 °C, preferably 70.5 to 150 °C. If the glass transition temperature is less than 70.0 °C, there is a concern that a product implemented through the second resin may change over time in a temperature condition such as summer, for example, higher than 40 °C.

Meanwhile, the first resin and the second resin may be prepared independently or together, but are not limited thereto.

Meanwhile, the first resin or the second resin may include a flame retardant, and preferably may include a flame retardant in the first resin or a flame retardant in the second resin.

In addition, the flame retardant may be included in the first resin or the second resin in an amount of 10 to 4,000 ppm, preferably in an amount of 50 to 3,000 ppm, and more preferably in an amount of 100 to 2,000 ppm. . If the flame retardant is included in less than 10 ppm, it is difficult to prevent high-temperature thermal decomposition, and discoloration may occur in the polyester resin. This may occur, and there may be a problem in that yarn cutting may occur in the spinning process.

More specifically, when the flame retardant is used in the first resin, the flame retardant may be added during the neutralization process or after the neutralization process is finished.

In addition, when the flame retardant is used in the second resin, in preparing the second resin, the polyester resin is esterified with an acid and a diol component to prepare an ester reaction product; and preparing a polyester resin by polycondensation reaction of the polycondensation reaction product including the ester reaction product and the flame retardant.

In addition, the flame retardant is to prevent discoloration through thermal decomposition at high temperature, and a phosphorus (P)-based flame retardant or a HALS-based flame retardant may be used. At this time, as a preferred example, the phosphorus-based flame retardant is selected from phosphoric acid, monomethyl phosphate, trimethyl phosphate, triethyl phosphate, and methyl diethyl phosphate acetate. It may include one or more, and the HALS-based flame retardant may preferably be a HALS-based-triazine-based flame retardant, and as long as it is a material containing hindered amine properties and triazine, the type is not significantly limited, Specifically poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl -4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-morphine-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexane diyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(1,2,2,6,6-pentamethyl -4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-morphine-1,3,5-triazine-2,4-diyl][(1,2,2,6,6-pentamethyl-4-piperidinyl)imino]-1,6 -hexanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4 -piperidinyl)imino]-1,5-pentanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-morphine-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,5-pentane diyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(1,2,2,6,6-pentamethyl -4-piperidinyl)imino]-1,5-pentanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-morphine-1,3,5-triazine-2,4-diyl][(1,2,2,6,6-pentamethyl-4-piperidinyl)imino]-1,5 -pentanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4 -piperidinyl)imino]-1,4-butanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-morphine-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,4-butane diyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; poly[[6-[1,1,3,3-tetramethylbutyl)amino]-1,3,5-triazine-2,4-diyl][(1,2,2,6,6-pentamethyl -4-piperidinyl)imino]-1,4-butanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; Poly[[6-morphine-1,3,5-triazine-2,4-diyl][(1,2,2,6,6-pentamethyl-4-piperidinyl)imino]-1,6 -butanediyl[(2,2,6,6-tetramethyl-4-pyreridinyl)imino]]; N,N',N",N"'-tetrakis{2,4-bis[(1-hydrocarbyloxy-2,2,6,6-tetramethylpiperidin-4-yl)alkylamino] -s-triazin-6-yl} -3,3'-ethylenediiminodipropylamine; 2,4-bis{N-[1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N-alkylamino}-6 -(2-hydroxymethylamino)-s-triazine; 2,4-bis[(1-hydrocarbyloxy-2,2,6,6-tetramethylpiperidin-4-yl)alkylamino]-6-(2-hydroxyethylamino)-s-tri ajin; 2,4-bis[(1-hydrocarbyloxy-2,2,6,6-piperidin-4-yl)alkylamino]-6-chloro-s-triazine; or N,N',N"'-tris{2,4-bis[(1-hydrocarbyloxy-2,2,6,6-tetramethylpiperidin-4-yl)alkylamino]-s- triazin-6-yl} -3,3'-ethylenediiminodipropylamine;

In addition, the first and second resins may be dissolved in an amide-based solvent to prepare a first spinning solution and a second spinning solution. In this case, the first spinning solution may be prepared by mixing 15 to 25 parts by weight of the first resin, preferably 22 to 24 parts by weight, with 100 parts by weight of the amide-based solvent. In addition, the second spinning solution may be prepared by mixing 10 to 30 parts by weight of the second resin, preferably 20 to 30 parts by weight, with 100 parts by weight of the amide-based solvent.

At this time, the amide-based solvent may preferably be a polar amide-based solvent, more preferably dimethyl acetamide, hexamethylphosphoamide, N-methylpyrrolidone, tetrahydrofuran, hexaflo It may include at least one selected from loisopropanol and dimethyl sulfoxide.

to the next. The two-step composite spinning may be performed at a spinning temperature of 230 to 290 ° C. and a spinning speed of 800 to 1500 mpm, preferably at a spinning temperature of 240 to 280 ° C. and a spinning speed of 900 to 1400 mpm. The first spinning solution and the second spinning solution are mixed in a weight ratio of 1:0.25 to 1:4.0, preferably in a weight ratio of 1:0.30 to 1:3.5, more preferably in a weight ratio of 1:0.67 to 1:1.5. Radiation can be obtained by irradiation.

In addition, the composite spinning can be performed by any generally usable spinning method, preferably dry spinning.

Next, prior to step 3, the spinning material may be fibrous through an ejection process in the spinning cylinder, and the spinning ejection process may be performed for 1.0 to 5.0 seconds at 200 to 400 ° C, preferably at 300 to 350 ° C. It can be carried out for 2.5 to 4.5 seconds under the pressure, and it can be carried out by the method of solvent removal through an inert hot gas medium.

Next, the preconditioning in the third step may be performed by contacting the spinning material subjected to the spinning discharge process with a preconditioning solution. The temperature of the preconditioning solution is significantly lower than the temperature of the radiation, and may be 0 to 10 ° C, preferably 2 to 8 ° C, and the solution may include a solvent, a salt and water, and preferably the The solution may include 4 to 40% by weight of the solvent, 0.3 to 15% by weight of the salt and the remaining water, more preferably 6 to 38% by weight of the solvent, 1.0 to 14% by weight of the salt and the remaining water. .

In addition, the solvent may include at least one selected from dimethyl acetamide, hexamethylphosphoamide, N-methylpyrrolidone, tetrahydrofuran, hexafluoro isopropanol, and dimethyl sulfoxide, and the salt is lithium It may include at least one selected from chloride (LiCl) and calcium chloride.

By performing the pre-conditioning, the temperature of the fiber can be reduced and a polymer-rich phase can be additionally generated on the surface of the fiber. If a stretching process that can be stretched by several times its unit length is immediately performed, there may be a problem in that the possibility of breakage of individual fibers increases. In order to solve the above problem, the pre-conditioning yarn in a wet state is placed in a tub for a predetermined period of time, which may be several hours to several days. In addition, the spinning material may be taken out of the vat and washed with water to remove the solvent, and at the same time a drawing process may be further performed on a series of rolls in a plurality of aqueous baths to a desired extent.

Meanwhile, after performing the preconditioning step, the bundle of fibers or filaments may further be subjected to a conditioning step in which the fibers are conditioned before the subsequent drawing step to prevent breakage of individual filaments in this continuous process. The conditioning step may be performed by spraying or dipping the conditioning solution onto continuously moving fibers. The conditioning solution may include a higher concentration of solvent than the preconditioning solution, may have a higher temperature than the preconditioning solution, and may use the same type of solvent and salt as the preconditioning solution. The temperature of the conditioning solution may be 25 to 110 ° C, preferably 40 to 95 ° C, and the solution may include 2 to 20% by weight of a solvent, 2 to 10% by weight of a salt, and the remaining amount of water, Preferably, 6 to 38% by weight of the solvent, 1.0 to 14% by weight of the salt, and the remaining water may be included.

Next, the stretching and heat treatment in step 4 is carried out at a stretching ratio of 1.5 to 5.0, preferably at a stretching ratio of 2.0 to 4.8, under 40 to 120 ° C., preferably at 45 to 100 ° C. can In addition, the stretching may be performed by a method of stretching in a warm bath.

The aramid composite fiber prepared by performing the above step 4 may further include a washing step. The washing is carried out by spraying water at 80 to 100 ° C., preferably at 85 to 95 ° C., on the surface of the composite fiber for 1 to 10 seconds, preferably 2 to 10 seconds, when the composite fiber passes over the roll. It can be carried out by spraying for 8 seconds, through which residual solvents and salts on the fiber surface can be washed and removed.

Referring to FIG. 1 for the aramid composite fiber manufactured through the above manufacturing method, the composite fiber may have a side-by-side type or sheath-core cross section. At this time, the core-sheath type is a sheath containing a first resin; and a core including a second resin.

The first resin (A in FIG. 1) may include a meta-aramid polymer in which aromatic diamine and aromatic diacid chloride are copolymerized, and the second resin (A' in FIG. 1) is a polyethylene terephthalate (PET) copolymer resin. Including, the PET resin may be characterized in that it is dissolved in an amide-based solvent. The amide-based solvent may include at least one selected from dimethyl acetamide, hexamethylphosphoamide, N-methylpyrrolidone, tetrahydrofuran, hexafluoroisopropanol, and dimethyl sulfoxide.

Meanwhile, the composite fiber may have a heat shrinkage rate of 25,000 to 50,000 ppm, preferably 28,000 to 49,500 ppm, and more preferably 33,000 to 49,000 ppm, as measured by the ASTM-E881 method. If the heat shrinkage rate is less than 25,000 ppm, it may be difficult to develop sufficient crimpability, and if it exceeds 50,000 ppm, manufacturing processability may be inhibited due to the expression of shrinkage during the manufacturing process.

Meanwhile, the number of crimps per inch of the composite fiber may be 17 to 30, preferably 18 to 28. If the number of crimps per inch is less than 17, there may be a problem in that the bulkiness of the fiber is significantly reduced, and if it exceeds 30, the fiber becomes excessively bulky, and the performance of the nonwoven fabric including it may deteriorate. .

At this time, the 'crimp number' means the wavy bend of the fiber, and can be expressed as 'crimp number' as another preferred expression.

In addition, the composite fiber may have a fineness of 0.5 to 5.0 denier (de), preferably 1.0 to 4.5 de, and the number of filaments may be 500 to 2,500, preferably 800 to 2,100.

In addition, in the aramid composite fiber, the cross-sectional area ratio of the first resin and the second resin may be 1:0.25 to 1:4.0, preferably 1:0.30 to 1:3.5, and more preferably 1:0.67 It can be ~ 1:1.5. If the cross-sectional area ratio is out of the above range, there may be problems in that the fusion of the composite fiber is impossible or the stability of the fiber shape of the second resin is lowered.

For another object of the present invention, a nonwoven fabric comprising the composite fiber at 5 to 80 parts by weight, preferably at 10 to 75 parts by weight, and more preferably at 15 to 70 parts by weight, based on 100 parts by weight of the nonwoven fabric can be prepared. If the composite fiber is included in less than 5 parts by weight, there may be a problem that the thickness of the manufactured nonwoven fabric is not thick enough, and if it contains more than 80 parts by weight, the thickness of the manufactured nonwoven fabric becomes excessively thick. there may be

Meanwhile, the nonwoven fabric may be a spunbond nonwoven fabric or a meltblown nonwoven fabric, and the single yarn fineness of the nonwoven fabric may be 0.5 to 5.0 denier, preferably 1.0 to 4.5 denier . If it is out of the range of the above fineness, there may be a problem that is difficult to manufacture by a general dry spinning method.

In addition, in the aramid composite fiber, the cross-sectional area ratio of the first resin and the second resin may be 1:0.25 to 1:4.0, preferably 1:0.30 to 1:3.5, and more preferably 1:0.67 It can be ~ 1:1.5. If the cross-sectional area ratio is out of the above range, there may be problems in that the fusion of the composite fiber is impossible or the stability of the fiber shape of the second resin is lowered.

For another object of the present invention, a nonwoven fabric comprising the composite fiber in an amount of 5 to 80 parts by weight, preferably 10 to 75 parts by weight, and more preferably 15 to 70 parts by weight based on 100 parts by weight of the nonwoven fabric can be prepared. If the composite fiber is included in less than 5 parts by weight, there may be a problem that the thickness of the manufactured nonwoven fabric is not thick enough, and if it contains more than 80 parts by weight, the thickness of the manufactured nonwoven fabric becomes excessively thick. there may be

Meanwhile, the nonwoven fabric may be used without limitation as long as it is a nonwoven fabric used in the art, but preferably, the nonwoven fabric may be a spunbond nonwoven fabric or a meltblown nonwoven fabric.

In addition, the nonwoven fabric may have a single yarn fineness of 0.5 to 5.0 denier, preferably 1.0 to 4.5 denier . If it is out of the range of the above fineness, there may be a problem that is difficult to manufacture by a general dry spinning method.

Hereinafter, the present invention will be described through the following examples. At this time, the following examples are only presented to illustrate the invention, and the scope of the present invention is not limited by the following examples.

[Example]

Preparation Example 1-1: Preparation of the first resin

100 parts by weight of dimethyl acetamide (amide solvent) 10 parts by weight of meta-phenylenediamine (aromatic diamine) and 19 parts by weight of isophthaloyl dichloride (diacid chloride) at 4 ° C. Mixing and Polymerized to produce a meta-aramid polymer.

In addition, calcium hydroxide (Ca(OH) ₂ ) was mixed with the meta-aramid polymer and the basic compound in a ratio of 1:1 to neutralize the mixture, and a first resin was obtained as a result.

Preparation Example 1-2: Preparation of the first resin

100 parts by weight of dimethyl acetamide (amide solvent) 10 parts by weight of meta-phenylenediamine (aromatic diamine) and 19 parts by weight of isophthaloyl dichloride (diacid chloride) at 4 ° C. Mixing and Polymerized to produce a meta-aramid polymer.

In addition, calcium hydroxide (Ca(OH) ₂ ) was mixed with the meta-aramid polymer and the basic compound in a 1: 1 ratio and neutralized to prepare a neutralized product, and triethyl phosphate as a flame retardant was added to the neutralized product as a first resin. It was added so as to be 2,000 ppm in the total weight, and a first resin was obtained as a result.

Preparation Example 2-1: Preparation of the second resin

(1) An ester reactant was prepared by introducing an acid component having a composition of 70 mol% of TPA and 30 mol% of IPA and a diol component having a composition of 50 mol% of EG and 50 mol% of NPG into a reactor at a ratio of 1:1.5.

(2) An ester reaction product was obtained by subjecting the ester reactant to an esterification reaction at 255° C. under a pressure of 1140 Torr.

(3) The ester reaction product was transferred to a polycondensation reactor.

(4) 350 ppm of a titanium citrate chelate polymerization catalyst and 2,000 ppm of triethyl phosphate as a flame retardant were introduced into the polycondensation reactor to prepare a polycondensation reaction product.

(5) The polymerization-condensation reaction was performed by raising the temperature to 280° C. while gradually reducing the pressure to a final pressure of 0.5 Torr to prepare a second resin containing a polyethylene terephthalate copolymer.

Preparation Example 2-2 ~ Preparation Example 2-5: Preparation of the second resin

A second resin was prepared in the same manner as in Preparation Example 2-1, but Preparation Examples 2-2 to 2-5 were prepared under the conditions shown in Table 1 below.

Preparation Example 2-6: Preparation of second resin

(1) An ester reactant was prepared by introducing an acid component having a composition of 70 mol% of TPA and 30 mol% of IPA and a diol component having a composition of 50 mol% of EG and 50 mol% of NPG into a reactor at a ratio of 1:1.5.

(2) An ester reaction product was obtained by subjecting the ester reactant to an esterification reaction at 255° C. under a pressure of 1,140 Torr.

(3) The ester reaction product was transferred to a polycondensation reactor.

(4) 350 ppm of a titanium citrate chelate polymerization catalyst was introduced into the polycondensation reactor to prepare a polycondensation reaction product.

(5) A second resin containing a polyester resin was prepared by heating the polycondensation reaction product to 280° C. while gradually reducing the pressure to a final pressure of 0.5 Torr to perform a polymerization/condensation reaction.

Comparative Preparation Example 2-1 ~ Comparative Preparation Example 2-7: Preparation of the second resin

A second resin was prepared in the same manner as in Preparation Example 2-1, but Comparative Preparation Examples 2-1 to Comparative Preparation Examples 2-7 were prepared under the conditions shown in Table 1 below.

Acid content (mol%) Diol component (mol%) Residual amount (ppm) TPA IPA AA DDDA EG NPG Ti P Preparation example 2-1 70 30 - - 50 50 15 26 Preparation example 2-2 60 40 - - 50 50 16 25 Preparation example 2-3 80 20 - - 50 50 14 26 Preparation example 2-4 70 30 - - 40 60 15 26 Preparation example 2-5 70 30 - - 60 40 15 24 Preparation example 2-6 70 30 - - 50 50 15 0 Comparative preparation example 2-1 50 50 - - 50 50 15 26 Comparative preparation example 2-2 40 60 - - 50 50 14 25 Comparative preparation example 2-3 100 - - - 50 50 15 23 Comparative preparation example 2-4 70 30 - - 100 - 14 25 Comparative preparation example 2-5 90 10 - - 70 30 14 25 Comparative preparation example 2-6 70 - 30 - 50 50 15 26 Comparative preparation example 2-7 70 - - 30 50 50 13 24

Experimental Example 1: Evaluation of resin properties

The resins of Preparation Example 1-1 ~ Preparation Example 1-2, Preparation Example 2-1 ~ Preparation Example 2-6 and Comparative Preparation Example 2-1 ~ Comparative Preparation Example 2-7 were evaluated in the following manner and are shown in Table 2 below. shown in

(1) Glass transition temperature (Tg)

The glass transition temperature was measured using a differential parking calorimeter (DSC), and the analysis condition was a heating rate of 20 ° C.

(2) Weight average molecular weight (Mw)

It was measured using gel permeation chromatography (GPC).

(3) solvent solubility

Dimethylformamide (DMF; amide-based) solvent was dissolved in 20 parts by weight in 100 parts by weight at 25 ° C., and whether the resin was completely dissolved was observed. The case where the resin was completely dissolved and transparent was marked as ○, and the case where undissolved resin remained or was opaque was marked as X.

Tg (℃) Mw solvent solubility Preparation example 1-1 268 364,259 ○ 1-2 on preparation 267 364,155 ○ Preparation example 2-1 71.7 58,732 ○ Preparation example 2-2 70.5 37,594 ○ Preparation example 2-3 73.1 33,022 ○ Preparation example 2-4 70.9 38,027 ○ Preparation example 2-5 72.7 43,045 ○ Preparation example 2-6 71.5 58,597 ○ Comparative preparation example 2-1 68.6 38,292 ○ Comparative preparation example 2-2 69.4 25,808 ○ Comparative preparation example 2-3 75.7 33,032 X Comparative preparation example 2-4 63.0 32,053 X Comparative preparation example 2-5 76.1 33,497 X Comparative preparation example 2-6 58.2 41,227 ○ Comparative preparation example 2-7 53.3 43,293 ○

Looking at Table 2, it was found that the first resins prepared in Preparation Examples 1-1 to 1-2 were well dissolved in amide-based solvents.

On the other hand, it can be seen that the second resins of Preparation Examples 2-1 to 2-6 all had high glass transition temperatures of 70.0° C. or higher, and excellent solubility in amide-based solvents.

On the other hand, in the case of Comparative Preparatory Example 2-1 prepared with more than 40 mol% of isophthalic acid, compared to Preparation Example 2-2 (40 mol% of isophthalic acid), there was a problem that the glass transition temperature was 70 ° C. or less.

In addition, in the case of Comparative Preparation Example 2-2 prepared with not only isophthalic acid exceeding 40 mol% but also terephthalic acid being less than 60 mol%, Preparation Example 2-2 (isophthalic acid 40 mol% and terephthalic acid 60 mol%) and In comparison, there was a problem that the glass transition temperature was 70 ° C or less.

In addition, in the case of Comparative Preparation Example 2-3 prepared with more than 80 mol% of terephthalic acid, compared to Preparation Example 2-3 (80 mol% of terephthalic acid), there was a problem of not dissolving in an amide-based solvent.

In addition, in the case of Comparative Preparation Example 2-4 prepared with less than 40 mol% of neopentyl glycol, compared to Preparation Example 2-5 (40 mol% of neopentyl glycol), it is not soluble in dimethylformamide (DMF) solvent. There was a problem that didn't.

In addition, in the case of Comparative Preparation Example 2-5 prepared with less than 20 mol% of isophthalic acid, compared to Preparation Example 2-3 (20 mol% of isophthalic acid), there was a problem of not dissolving in an amide-based solvent.

In addition, Comparative Preparation Examples 2-6 and Comparative Preparation Examples 2-7 in which adipic acid and dodecanedioic acid were added instead of isophthalic acid had a problem that the glass transition temperature was 70 ° C or less.

Example 1: Preparation of aramid composite fibers

The first resin prepared in Preparation Example 1-1 and the second resin prepared in Preparation Example 2-1 were mixed at 20 parts by weight with 100 parts by weight of dimethyl acetamide (amide-based solvent) at 25 ° C. 1 spinning bath liquid and 2nd spinning bath liquid were prepared.

In addition, the first spinning solution and the second spinning solution are combined-spun at a spinning temperature of 350 ° C. and a spinning speed of 100 mpm (meter per minute) under gaseous nitrogen at a weight ratio of 1: 0.25 to side-by-side (side-by-side). side) type yarn was prepared, and the yarn was contacted with a preconditioning solution at 10° C. for 0.5 second. At this time, the preliminary conditioning solution was prepared by including 10% by weight of the solvent, 4% by weight of the salt and the remaining amount of water.

Then, the spinning material was contacted with the conditioning solution at 25° C. for 60 minutes. At this time, the conditioning solution was prepared by including 15% by weight of the solvent, 4% by weight of the salt and the remaining amount of water.

Then, the spinning material was stretched in a warm bath at a draw ratio of 3.5 at 90° C. to prepare latent crimp-type aramid composite fibers.

Then, when the composite fiber passed over the roll, water at 90° C. was sprayed on the surface of the composite fiber for 4 seconds to wash and remove residual solvent and salt on the surface of the fiber.

Then, the composite fibers were dried. The composite fiber thus prepared has a cross-sectional area ratio of the first resin and the second resin of 1:0.25, a fineness of 2.0 denier, and a number of filaments of 800 strands.

Examples 2 to 4 and Comparative Examples 1 to 6: Preparation of aramid composite fibers

Examples 2 to 4 and Comparative Examples 1 to 6 were prepared in the same manner as in Example 1, but under the conditions of Tables 3 to 4 below.

Experimental Example 2: Evaluation of aramid composite fibers

1st resin, 2nd resin (Preparation Example 1-1~ Preparation Example 1-2, Comparative Preparation Example 2-1~ Comparative Preparation Example 2-2 and Comparative Preparation Example 2-6~ Comparative Preparation Example 2-7) and composite Fibers (Examples 1 to 3 and Comparative Examples 1 to 6) were evaluated in the following manner and are shown in Tables 3 to 4 below.

(1) Measuring the number of crimps (number of crimps)

The number of crimps per inch (crimp number) was measured.

(2) Measurement of heat shrinkage rate

Heat shrinkage was measured through the ASTM -E881 method.

(3) Strength (tensile strength) measurement

Strength was measured at 20° C. and 65% RH (atmospheric standard conditions) by a constant rate descent method (a method in which a sample is stretched at a constant rate).

(4) Measurement of elongation

It was measured using a VIBROSKOP device at 20 ° C. and 65% RH (atmospheric standard conditions), and the length stretched until the fiber was stretched to the point of breakage was expressed as a percentage of the difference from the initial length of the fiber.

Example 1 Example 2 Example 3 Example 4
division Resin 1 Preparation example 1-1 Preparation example 1-2 Preparation example 1-1 Preparation example 1-1 2nd Resin preparation example
2-1 preparation example
2-6 preparation example
2-1 preparation example
2-1 1st resin: 2nd resin cross-sectional area ratio 1:1.0 1:1.0 1:0.25 1:4.0 Fineness (de)/Number of filaments 2.0/800 2.0/800 2.0/800 2.0/800 Crimp Number [ea/in.] 24 24 18 19 Composite fiber heat shrinkage rate [ppm] 44,000 43,000 38,000 49,000 Strength [g/d] 3.9 3.8 4.0 3.8 Believer [%] 35 34 33 35

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4
division Resin 1 Preparation example 1-1 - Preparation example 1-1 Preparation example 1-1 2nd Resin - preparation example
2-1 preparation example
2-1 preparation example
2-1 1st resin: 2nd resin cross-sectional area ratio - - 1:0.1 1:4.5 Fineness (de)/Number of filaments 2.0/800 2.0/800 2.0/800 2.0/800 Crimp Number [ea/in.] 12 16 14 16 Composite fiber heat shrinkage rate [ppm] 20,000 58,000 32,000 51,000 Strength [g/d] 4.1 3.8 4.0 3.7 Believer [%] 32 37 33 30

Looking at Tables 2 to 4, Examples 1 to 4 in which the cross-sectional area ratio of the first resin and the second resin was 1: 0.25 to 1: 4.0 had an excellent bulkiness with a crimp number of 17 or more, and a high heat shrinkage rate. Since it is within 25,000 to 50,000 ppm, it was confirmed that it had excellent crimpability and excellent processability.

On the other hand, Comparative Example 1 in which the first resin containing the meta-aramid polymer was spun alone had less than 17 crimps per inch and less than 25,000 ppm of heat shrinkage, resulting in poor bulkiness and poor crimpability. There was a problem that rarely manifested itself.

In addition, Comparative Example 2 in which the second resin was spun alone had less than 17 crimps per inch and a heat shrinkage rate of more than 50,000 ppm, resulting in poor bulkiness and poor fairness due to excessive shrinkage during the process. There was a problem with termination.

In addition, Comparative Example 3 in which the cross-sectional area ratio of the first resin and the second resin was less than 1:0.25 had a problem in that the number of crimps was less than 17 compared to Example 2 (area ratio of 1:0.25).

In addition, Comparative Example 4, in which the cross-sectional area ratio of the first resin and the second resin exceeds 1:4.0, has a heat shrinkage rate of 50,000 ppm as well as less than 17 crimps compared to Example 3 (area ratio of 1:4.0). There was an overshoot problem.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments can be easily proposed by means of changes, deletions, additions, etc., but these will also fall within the scope of the present invention.

A: first resin A': second resin

Claims (10)

A first resin comprising a meta-aramid polymer; And a second resin comprising a polyethylene terephthalate (PET) copolymer having a glass transition temperature of 70 to 150 ° C. As a composite fiber comprising a,
It is a side-by-side type composite fiber or a core-sheath type composite fiber,
The polyethylene terephthalate copolymer, which is the second resin, is a polycondensation product of an ester reaction product obtained by esterification of an acid and a diol component,
The acid includes 20 to 40 mol% of isophthalic acid and the balance of terephthalic acid,
The diol includes 40 to 60 mol% of neopentyl glycol and the remaining amount of ethylene glycol,
The second resin is dissolved in an amide-based solvent, and the amide-based solvent is one selected from dimethyl acetamide, hexamethylphosphoramide, N-methylpyrrolidone, tetrahydrofuran, hexafluoroisopropanol, and dimethyl sulfoxide including more than
The composite fiber has a heat shrinkage rate of 25,000 to 50,000ppm as measured by the ASTM-E881 method, and a crimping number (crimp number) per inch of 17 to 30. Aramid composite fiber with excellent crimpability.
According to claim 1,
The first resin is an aramid composite fiber with excellent crimpability, characterized in that it comprises a polymer in which aromatic diamine and aromatic diacid chloride are copolymerized.
delete delete According to claim 1,
The composite fiber is an aramid composite fiber with excellent crimpability, characterized in that the cross-sectional area ratio of the first resin and the second resin is 1: 0.25 to 1: 4.0.
delete According to claim 1,
The core-sheath type conjugate fibers include a core portion comprising a polyethylene terephthalate copolymer; And a sheath containing a meta-aramid polymer; aramid composite fiber with excellent crimpability, characterized in that it comprises a.
delete According to claim 1,
The composite fiber is an aramid composite fiber with excellent crimpability, characterized in that the single yarn fineness is 0.5 to 5.0 denier.
A nonwoven fabric comprising 5 to 80 parts by weight of the aramid composite fiber of any one of claims 1, 2, 5, 7 and 9.

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