JP5102723B2 - Crimpable composite fiber and fiber structure using the same - Google Patents

Description

  The present invention relates to a crimpable conjugate fiber suitable for a nonwoven fabric mainly excellent in bulk elasticity and a fiber structure using the same.

  Low melting point at least partially exposed on the fiber surface in various applications such as sanitary materials, packaging materials, non-woven fabrics used in wet tissues, filters, wipers, etc., non-woven fabrics used in hard cotton, chairs, etc., molded products A heat-bonding nonwoven fabric using a heat-fusible composite fiber composed of a component and a high-melting component having a melting point higher than that of the low-melting component is used. In particular, the demand for fibers excellent in bulk elasticity of the nonwoven fabric, that is, in the bulk recovery property in the thickness direction, is increasing as a substitute for urethane foam, and various studies have been made on nonwoven fabrics excellent in bulk recovery property.

  For example, Patent Document 1 discloses a composite fiber composed of a core component containing a polyester-based polymer and a sheath component containing a polyolefin-based polymer, and the center of gravity of the first component is shifted from the center of gravity of the fiber in the fiber cross section. is suggesting. In Patent Document 1, as described above, a polymer having a high bending elasticity and a low bending hardness is used as the first component. Further, in the fiber cross section, the center of gravity of the first component and the center of gravity of the entire fiber are determined. By shifting the crimped shape into a wave shape, a nonwoven fabric having a bulk recoverability and a large initial bulk is obtained. However, although the nonwoven fabric using the composite fiber proposed in Patent Document 1 has a large initial nonwoven fabric thickness (initial volume), it cannot be said that the bulk recovery property, particularly the initial bulk recovery property immediately after dewetting, is sufficient. There was a problem that was limited.

Therefore, Patent Document 2 discloses a crimpable conjugate fiber containing a sheath component including polybutene-1 (hereinafter also referred to as PB-1) and polypropylene, and excellent bulk recovery using the same and initial bulk recovery. An improved nonwoven fabric is proposed.
JP 2003-3334 A JP 2007-126806 A

  However, when the composite fiber proposed in Patent Document 2 and nonwoven fabrics using the same are heat-processed and bonded to each other at a temperature higher than the melting point of polybutene-1, the sheath at the bonding point between the fiber and the fiber There has been a problem that a so-called “adhesion point thinning” occurs in which the portion is thinned and the adhesion point is reduced.

  In order to solve the above-mentioned conventional problems, the present invention provides a crimped conjugate fiber that is excellent in thermal adhesiveness, and that can obtain a fiber structure in which the adhesion point between constituent fibers does not decrease even when thermally processed at high temperature, and a method for producing the same And a fiber structure using the same.

  The crimpable conjugate fiber of the present invention is a conjugate fiber comprising a first component and a second component, wherein the first component comprises polybutene-1 and an ethylene-ethylenically unsaturated carboxylic acid copolymer. And the ethylene-ethylenically unsaturated carboxylic acid copolymer is 5 to 20% by mass with respect to the first component, and the second component is melted at 20 ° C. or more higher than the melting peak temperature of polybutene-1. A polymer having a peak temperature or a polymer having a melting start temperature of 120 ° C. or higher, and in the fiber cross section, the first component occupies at least 20% of the surface of the composite fiber, and the center of gravity of the second component is the composite The composite fiber is deviated from the center of gravity of the fiber, and the composite fiber is an actual crimp expressing a three-dimensional crimp or a latent crimp expressing a three-dimensional crimp when heated.

  The fiber structure of the present invention contains at least 30% by mass of the crimped conjugate fiber of the present invention.

  The crimped conjugate fiber of the present invention selects polybutene-1 as the first component, further exhibits appropriate compatibility with polybutene-1, and heat-processes the obtained conjugate fiber to obtain a heat-bonded nonwoven fabric or the like. Fiber excellent in post-processability such as spinnability, stretchability, and thermal adhesiveness by blending with an ethylene-ethylenically unsaturated carboxylic acid copolymer that has the effect of suppressing “bonding point thinning” that may occur It becomes. And the nonwoven fabric which is excellent in bulk recovery property and is excellent also in heat adhesiveness can be obtained by using the crimpable conjugate fiber of this invention.

  The nonwoven fabric using the crimped conjugate fiber of the present invention is superior in both initial bulk and bulk recovery properties compared with a nonwoven fabric made of a conjugate fiber using a conventional elastomer. It can also be used in low density nonwoven products such as packaging materials, filters, cosmetic materials, women's bra pads, shoulder pads.

  In the crimped conjugate fiber of the present invention, the first component contains polybutene-1 and an ethylene-ethylenically unsaturated carboxylic acid copolymer. Moreover, the crimpable composite in which the flexibility and shape maintaining property (return to deformation) of polybutene-1 is utilized by arranging the first component so as to occupy at least 20% of the surface of the composite fiber. Fiber is obtained. Furthermore, since the first component does not contain a soft component such as an elastomer and has excellent heat resistance, the nonwoven fabric using the crimped conjugate fiber has a small volume reduction (sagging) during heat processing, The initial bulk can be large.

  In addition, in the present invention, the first component contains an ethylene-ethylenically unsaturated carboxylic acid copolymer in addition to polybutene-1, so that spinnability such as uniform fiber formation and stretchability at the time of melt spinning, It has been found that heat shrinkability during heat processing can be improved. That is, when melt spinning is performed only with polybutene-1, the problem is that the viscosity of the nozzle discharge polymer is not stable and it is difficult to obtain uniform fibers, and polybutene-1 has a high molecular weight and has a low degree of freedom in molecular chains. It is difficult to carry out the stretching process from the above, and in addition, since the heat shrinkability is very large, the fiber is shrunk during the heat processing, and polybutene-1 which is said to be difficult to obtain a nonwoven fabric with good formation has Problems such as poor spinnability and difficult stretchability can be solved.

  Further, the nonwoven fabric in which the fibers constituting the fiber web are thermally bonded to each other by thermally processing the fiber web containing the crimped conjugate fiber of the present invention can be subjected to thermal processing at a high temperature for a long time. 6, a phenomenon in which the sheath component is thinned and the thermal bonding point is reduced at the point where the constituent fibers are thermally bonded to each other (hereinafter referred to as thermal bonding point). Since it is difficult to occur, it is possible to strongly heat-bond the constituent fibers together, and it has been found that a heat-bonding nonwoven fabric with high adhesive strength can be obtained.

  Polybutene-1 used in the present invention preferably has a melting peak temperature of 115 to 130 ° C. determined from a DSC curve measured according to JIS-K-7121. More preferably, it is 120-130 degreeC. When the melting peak temperature is 115 to 130 ° C., the heat resistance is high, and the bulk recovery property at high temperature is good.

  The polybutene-1 has a melt flow rate (MFR; measurement temperature 190 ° C., load 2.16 kgf (21.18 N), hereinafter referred to as MFR190) measured in accordance with JIS-K-7210 1-30 g. / 10 minutes is preferable. A more preferred MFR 190 is 3-25 g / 10 min, even more preferably 3-20 g / 10 min. When MFR190 is 1 to 30 g / 10 min, polybutene-1 has a high molecular weight, and therefore, heat resistance is good, and bulk recovery when heated is high, which is preferable. Further, the take-up property of spinning and the stretchability are improved.

  The ethylenically unsaturated carboxylic acid constituting the ethylene-ethylenically unsaturated carboxylic acid copolymer used in the present invention is not particularly limited, but examples thereof include acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, maleic acid, Itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride, itaconic anhydride and the like can be mentioned.

  Specific examples of the ethylene-ethylenically unsaturated carboxylic acid copolymer include an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer (EMAA), an ethylene-ethacrylic acid copolymer, and an ethylene-maleic acid copolymer. Examples of the copolymer include an ethylene-fumaric acid copolymer, an ethylene-itaconic acid copolymer, an ethylene-maleic anhydride copolymer, and an ethylene-itaconic anhydride copolymer. Among these, an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, and an ethylene-maleic acid copolymer are preferable, and an ethylene-acrylic acid copolymer and an ethylene-methacrylic acid copolymer are more preferable.

  The ethylene-ethylenically unsaturated carboxylic acid copolymer is not limited to a copolymer composed of ethylene and an ethylenically unsaturated carboxylic acid, but includes, for example, two or more types of components containing ethylenically unsaturated carboxylic acid in ethylene. It may be a copolymer in which other components are copolymerized, including a copolymerized terpolymer (terpolymer).

  Examples of the monomer used as the other copolymerization component include vinyl esters such as vinyl acetate and vinyl propionate, methyl acrylate, ethyl acrylate, isopropyl acrylate, nbutyl acrylate, isobutyl acrylate, and acrylic acid. Ethylenic unsaturated carboxylic acid esters such as acrylic acid esters such as isooctyl, methacrylic acid esters such as methyl methacrylate and isobutyl methacrylate, maleic acid esters such as dimethyl maleate and diethyl maleate, carbon monoxide, sulfur dioxide, etc. Is mentioned.

  The copolymer in which ethylene, ethylenically unsaturated carboxylic acid and any other copolymerization component are copolymerized is not particularly limited. For example, ethylene, maleic anhydride, and an acrylic ester are copolymerized. An ethylene-acrylate-maleic acid polymer (manufactured by Arkema Japan, “Bondaine”) and the like can be mentioned.

  The ethylenically unsaturated carboxylic acid content in the ethylene-ethylenically unsaturated carboxylic acid copolymer is 1 to 50% by mass, preferably 1 to 29% by mass. In particular, in the case of acrylic acid, it is preferably 5 to 25% by mass, and in the case of methacrylic acid, it is preferably 5 to 20% by mass. Moreover, content of the other copolymerization component in the said ethylene-ethylenically unsaturated carboxylic acid copolymer is 0-30 mass%, Preferably it is the range of 0-20 mass%.

  In the present invention, as the ethylene-ethylenically unsaturated carboxylic acid copolymer, in addition to the ethylene-ethylenically unsaturated carboxylic acid copolymer itself, an ionomer in which a part or all of the carboxyl group is converted into a metal salt. Can be used. Examples of the metal species constituting the ionomer include monovalent metals such as lithium, sodium, and potassium, and polyvalent metals such as magnesium, calcium, zinc, copper, cobalt, manganese, lead, and iron. Or zinc is preferable.

  Moreover, in this invention, said ethylene-ethylenically unsaturated carboxylic acid copolymer may be used independently, and may be used in combination of 2 or more type.

  Although the said ethylene-ethylenically unsaturated carboxylic acid copolymer is not specifically limited, For example, it can obtain by high pressure radical copolymerization. The ethylene-ethylenically unsaturated carboxylic acid copolymer ionomer can be obtained by ionizing the ethylene-ethylenically unsaturated carboxylic acid copolymer by a conventional method.

  Polybutene produced when the compatibilizing effect on polybutene-1 is too low by blending an ethylene-ethylenically unsaturated carboxylic acid copolymer exhibiting an appropriate compatibilizing effect with polybutene-1 as described above. Since the spinnability of -1 is not improved, the problem that it is difficult to obtain a uniform composite fiber can be solved. Moreover, although the composite fiber which consists of the 1st component mainly containing polybutene-1 produced when the compatibilizing effect to polybutene-1 is too high is obtained, when producing a thermobonding nonwoven fabric from the obtained composite fiber, It is possible to solve the problem that adhesion points and thinness are generated by heat processing. That is, by blending polybutene-1 with an ethylene-ethylenically unsaturated carboxylic acid copolymer that exhibits an appropriate compatibilizing effect, it becomes possible to obtain a uniform composite fiber containing them and further obtain it. The thermal adhesiveness of the composite fiber thus obtained is improved, and the adhesive point and the thinness that may occur when the thermal processing is performed at a temperature higher than the melting point of polybutene-1 to be bonded can be eliminated.

  In the first component, the amount of the ethylene-ethylenically unsaturated carboxylic acid copolymer added may be 5 to 20% by mass, and 7 to 15% by mass when the entire first component is 100% by mass. It is preferable that If it is 5% by mass or more, a crimpable conjugate fiber excellent in thermal adhesiveness can be obtained, and even at a high temperature, for example, 190 ° C. or higher, the adhesive strength between the fibers does not decrease, and the above adhesion point can be reduced. Does not occur. Moreover, by being 20 mass% or less, fiber structures, such as a nonwoven fabric, with favorable hardness retainability (bulk recovery property) are obtained.

  The ethylene-ethylenically unsaturated carboxylic acid copolymer preferably has an MFR190 of 3 to 60 g / 10 min measured according to JIS-K-7210. A more preferred MFR 190 is 5 to 40 g / 10 min, even more preferably 5 to 30 g / 10 min. When MFR190 is 60 g / 10 or less, the effect which suppresses the adhesive point thinning which may arise when heat-processing to the fiber web containing the obtained crimpable conjugate fiber can be improved. Moreover, when MFR190 is 3 g / 10min or more, it is excellent in the operativity in a spinning process and a drawing process, and it becomes easy to obtain a uniform crimpable conjugate fiber.

  The ethylene-ethylenically unsaturated carboxylic acid copolymer preferably has a melting peak temperature determined from a DSC curve measured according to JIS-K-7121 of 60 ° C or higher, preferably 70 ° C or higher. Is more preferable, and it is still more preferable that it is 70-120 degreeC. When the melting peak temperature is 60 ° C. or higher, the effect of suppressing the adhesion point thinness is high, and it is difficult for the cushion performance to be reduced such as a decrease in bulk recovery property and an increase in compressive strain rate due to thermal processing. Moreover, when the melting peak temperature is 70 to 120 ° C., the effect of suppressing the adhesion point and the thinness, the effect of suppressing the deterioration of the cushioning performance, and the like can be exhibited better.

  The ethylene-ethylenically unsaturated carboxylic acid copolymer preferably has a softening temperature (Vicat softening point) measured according to JIS-K-7206 of 40 ° C or higher, more preferably 50 ° C or higher. Yes, and particularly preferably 50 to 100 ° C. When the softening temperature is 40 ° C. or higher, the effect of suppressing the adhesive point thinness is high, and the cushioning performance such as the decrease in bulk recovery property and the increase in the compressive strain rate due to thermal processing is less likely to occur. When the softening temperature is 50 to 100 ° C., the effect of suppressing the adhesion point thinness and the effect of suppressing the deterioration of the cushion performance can be exhibited better.

  The first component may further contain polypropylene (hereinafter also referred to as PP). By further blending the first component with polypropylene that is easily compatible with polybutene-1, the spinnability and stretchability of the crimped conjugate fiber become better, and the single fiber thermal shrinkage also becomes smaller. That is, by further including polypropylene in the first component containing polybutene-1 and an ethylene-ethylenically unsaturated carboxylic acid copolymer, in the crimped conjugate fiber by the ethylene-ethylenically unsaturated carboxylic acid copolymer, In addition to improving spinnability such as adhesion point, thinness, stretchability, and heat shrinkability during heat processing, spinnability, stretchability, heat shrinkability, and the like can be further improved.

  The polypropylene is not particularly limited. For example, the polypropylene does not impair the characteristics required for a homopolymer, a random copolymer, a block copolymer, or a mixture thereof, and a nonwoven fabric or cushion material such as heat resistance and bulk recovery. For example, polypropylene in which an elastomer component such as synthetic rubber is dispersed or mixed in polypropylene may be used. However, in consideration of heat shrinkability, a homopolymer or a block copolymer is preferable. In particular, homopolymers are preferable because they are advantageous in bulk recovery.

  The polypropylene has a melt flow rate (MFR; measurement temperature 230 ° C., load 2.16 kgf (21.18 N), hereinafter referred to as MFR230) measured according to JIS-K-7210 at 5 to 30 g / 10 minutes. Preferably there is. A more preferred MFR 230 is 6-25 g / 10 min. When the MFR230 is 5 to 30 g / 10 min, the decrease in the melt viscosity of the polybutene-1 can be suppressed, and since the polypropylene has an appropriate molecular weight for entering between the molecular chains of the polybutene-1, it is uniform. Fiber is obtained and heat shrinkage can be reduced.

  The ratio (Q value) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the polypropylene is preferably 6 or less. A more preferable Q value is 2 to 5. When the Q value is 6 or less, that is, the molecular weight distribution is small, the content of the high molecular weight polypropylene is reduced, so that the polypropylene easily enters between the molecular chains of the polybutene-1, and as a result, the thermal shrinkage can be reduced.

  In the first component, when polypropylene is added as described above, the amount of the polypropylene added may be 1 to 20% by mass when the entire first component is 100% by mass, and 7 to 15% by mass. Preferably there is. When the addition amount of polypropylene is 1 to 20% by mass, the stretchability is improved, the heat shrinkability is small, and the stability of the melt viscosity is also improved.

  When polypropylene is added to the first component as described above, the first component is 60 to 94% by mass of polybutene-1, 1 to 20% by mass of polypropylene, and 5 to 5% of an ethylene-ethylenically unsaturated carboxylic acid copolymer. It is preferable to contain 20% by mass. Moreover, the compounding ratio of the polypropylene and the ethylene-ethylenically unsaturated carboxylic acid copolymer in the first component is, by mass ratio, polypropylene: ethylene-ethylenically unsaturated carboxylic acid copolymer = 1: 2 to 12: 5. Preferably there is. When the blending ratio of the polypropylene and the ethylene-ethylenically unsaturated carboxylic acid copolymer satisfies the above range, the spinnability is improved and the resulting fiber web containing the crimped conjugate fiber is heat-processed. The generation of the adhesion point and the skinnyness is also suppressed, and the resulting fiber structure also has high peel strength and bulk recovery. Further, the blending ratio of the polypropylene and the ethylene-ethylenically unsaturated carboxylic acid copolymer is, by mass ratio, polypropylene: ethylene-ethylenically unsaturated carboxylic acid copolymer = 7: 10 to 12: 5. A ratio of 4: 5 to 11: 5 is particularly preferable.

  As a polymer that can be further blended with the first component, for example, a copolymer polymer with an olefin having a polar group such as a vinyl group, a carboxyl group, or maleic anhydride, or an elastomer such as a styrene, as long as the effects of the present invention are not impaired. Etc.

  The second component of the crimped conjugate fiber of the present invention may be a polymer having a melting peak temperature that is 20 ° C. or more higher than the melting peak temperature of polybutene-1, or a polymer having a melting start temperature of 120 ° C. or more. Although not particularly limited, a polymer excellent in bending strength and bending elasticity is preferable. For example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, nylon 6, nylon 66, nylon 11 , Polyamides such as nylon 12, polypropylene, polycarbonate, polystyrene and the like. When using said polymer as a 2nd component, a polymer may be used independently and may be used in combination of 2 or more type. In the crimped conjugate fiber of the present invention, the polymer used for the second component is preferably a polyester-based resin, and is also referred to as polyethylene terephthalate (hereinafter also referred to as PET) or polytrimethylene terephthalate (hereinafter also referred to as PTT). ) And polybutylene terephthalate (hereinafter also referred to as PBT).

  The intrinsic viscosity [η] of the polyester is preferably 0.4 to 1.2. More preferably, it is 0.5 to 1.1. When the intrinsic viscosity is less than 0.4, the molecular weight of the polymer is too low, so that not only the spinnability is inferior, but also the fiber strength is low and the practicality is poor. If the intrinsic viscosity exceeds 1.2, the molecular weight of the polymer becomes large and the melt viscosity becomes too high, so that single yarn breakage or the like occurs and it becomes difficult to perform good spinning. Further, by setting the intrinsic viscosity [η] within the above range, a composite fiber having excellent productivity and excellent bulk elasticity can be obtained. The intrinsic viscosity [η] referred to here is a value obtained by measuring with an Ostwald viscometer as an o-chlorophenol solution at 35 ° C., based on the following formula 1.

[Equation 1]

  However, in the above formula 1, ηr is a value obtained by dividing the viscosity at 35 ° C. in a diluted solution of a sample dissolved in o-chlorophenol having a purity of 98% or more by the concentration of the whole solvent measured at the same temperature, and C Is the solute weight value in grams per 100 ml of the solution.

  It is preferable that the melting peak temperature calculated | required from the DSC curve measured according to JIS-K-7121 of the said polyester is 180 to 300 degreeC. More preferably, it is 200 degreeC-270 degreeC. When the melting peak temperature is 180 to 300 ° C., the weather resistance is high, and the flexural modulus of the resulting composite fiber can be increased.

  In the crimped conjugate fiber of the present invention, the position of the center of gravity of the second component is shifted from the position of the center of gravity of the conjugate fiber. FIG. 1 shows a schematic diagram of a fiber cross section of a crimped conjugate fiber according to an embodiment of the present invention. The first component 1 is disposed around the second component 2, and the first component 1 occupies at least 20% of the surface of the composite fiber 10. As a result, the surface of the first component 1 is melted during thermal bonding. The gravity center position 3 of the second component 2 is shifted from the gravity center position 4 of the composite fiber 10, and the ratio of the shift (hereinafter also referred to as the eccentricity ratio) is obtained by enlarging the cross section of the crimped conjugate fiber with an electron microscope or the like. When the image is taken and the center of gravity position 3 of the second component 2 is C1, the center of gravity position 4 of the conjugate fiber 10 is Cf, and the radius 5 of the conjugate fiber 10 is rf, the numerical value shown by the following formula 2 is used.

[Equation 2]

  The fiber cross section in which the center of gravity position 3 of the second component 2 is displaced from the center of gravity position 4 of the composite fiber is preferably an eccentric core-sheath type or a parallel type as shown in FIG. Depending on the case, even a multi-core type may be used in which multi-core portions are gathered and are shifted from the center of gravity of the fiber. In particular, an eccentric core-sheath fiber cross section is preferable in that desired wave shape crimps and / or spiral crimps can be easily expressed. The eccentricity ratio of the eccentric core-sheath composite fiber is preferably 5 to 50%. A more preferable eccentricity is 7 to 30%. Further, the shape of the second component 2 in the fiber cross section may be oval, Y-shaped, X-shaped, well-shaped, polygonal, star-shaped or the like other than circular, and the shape of the composite fiber 10 in the fiber cross-section. In addition to the circular shape, an elliptical shape, a Y shape, an X shape, a well shape, a polygonal shape, a star shape, or a hollow shape may be used.

  In the crimped conjugate fiber of the present invention, as shown in FIG. 1, in the fiber cross section, the first component is arranged as the sheath component of the conjugate fiber, the second component is arranged as the core component, and the center of gravity of the second component When the position is an eccentric core-sheath structure deviated from the position of the center of gravity of the composite fiber, the composite ratio (core / sheath) of the second component and the first component is preferably 8/2 to 2/8 in volume ratio. More preferably, it is 7/3 to 3/7, and still more preferably 6/4 to 4/6. The second component serving as the core component mainly contributes to the bulk recovery property, and the first component serving as the sheath component mainly contributes to the strength of the nonwoven fabric and the hardness of the nonwoven fabric. When the composite ratio is 8/2 to 2/8, the strength and hardness of the nonwoven fabric and the bulk recoverability can be compatible. If the first component that is the sheath component is too much, the strength of the nonwoven fabric is increased, but the resulting nonwoven fabric tends to be hard and the bulk recovery tends to be poor. On the other hand, when the second component serving as the core component increases too much, the adhesion point decreases too much, and the strength of the nonwoven fabric tends to decrease, and the bulk recovery property tends to deteriorate.

  FIG. 2 shows the crimped form of the crimped conjugate fiber in one embodiment of the present invention. In the present invention, “the composite fiber expresses a three-dimensional crimp” means that the crimp shape in which the crimpable conjugate fiber expresses includes a wave crimp and / or a spiral crimp. . The corrugated crimp referred to in the present invention refers to a curved crest as shown in FIG. 2A. In addition, the spiral crimp indicates that the peak portion of the crimp as shown in FIG. 2B is spirally curved. Crimps in which corrugated crimps and spiral crimps are mixed as shown in FIG. 2C are also included in the crimped form of the three-dimensional crimps that the crimped conjugate fiber of the present invention exhibits. In the case of normal mechanical crimping as shown in FIG. 3, the crimped mountain has a sharp angle, that is, a so-called serrated crimp, and it tends to be difficult to increase the initial bulk when the nonwoven fabric is used. There is. Furthermore, it is inferior to the surface elasticity against compression, the so-called spring effect, and there is a tendency that sufficient initial bulk recovery is not obtained. In addition, as shown in FIG. 4, a crimp in which a sharp crimp of a mechanical crimp and a wave crimp are mixed, and although not shown in the figure, a sharp crimp of a mechanical crimp and a spiral crimp. Are included in the crimped form of the three-dimensional crimp that the crimped conjugate fiber of the present invention develops.

  In the crimpable conjugate fiber of the present invention, particularly the crimping in which the wave-shaped crimp and the spiral crimp shown in FIG. 2C are mixed can satisfy both the card passing property and the initial bulk and bulk recovery properties. Is preferable.

  Hereinafter, the manufacturing method of the crimpable conjugate fiber of this invention is demonstrated.

  First, a method for producing an actual crimpable conjugate fiber, which is one form of the crimped conjugate fiber of the present invention, will be described.

  First, a first component containing polybutene-1 and an ethylene-ethylenically unsaturated carboxylic acid copolymer, a polymer having a melting peak temperature 20 ° C. higher than the melting peak temperature of polybutene-1, or a melting start temperature A second component which is a polymer having a temperature of 120 ° C. or higher is prepared. In addition, in a 1st component, an ethylene-ethylenically unsaturated carboxylic acid copolymer is 5-20 mass% with respect to a 1st component. Next, in the fiber cross section, the first component occupies at least 20% of the surface of the composite fiber, and the center of gravity of the second component is displaced from the center of gravity of the composite fiber, for example, an eccentric core-sheath type composite The first component and the second component are supplied to the nozzle, the second component is melt-spun at a spinning temperature of 240 to 330 ° C., the first component is melted at a spinning temperature of 200 to 300 ° C., and taken up at a take-up speed of 100 to 1500 m / min. Get the filament. Next, the stretching temperature is set to a temperature not lower than the glass transition point of the second component and lower than the melting point of the first component, and a stretching treatment is performed at a stretching ratio of 1.8 times or more. A more preferable lower limit of the stretching temperature is a temperature 10 ° C. higher than the glass transition point of the second component. A more preferable upper limit of the stretching temperature is 90 ° C. If the stretching temperature is lower than the glass transition point of the second component, the crystallization of the first component is difficult to proceed, so that thermal shrinkage tends to increase or the bulk recovery property tends to decrease. If the stretching temperature is equal to or higher than the melting point of the first component, the fibers tend to be fused. A more preferable lower limit of the draw ratio is 2 times. A more preferable upper limit of the draw ratio is 4 times. When the draw ratio is 1.8 times or more, the draw ratio is not too low, and it becomes easy to obtain a fiber in which the above-described wave-shaped crimp and / or spiral crimp are expressed, and the initial bulk and the rigidity of the fiber itself are obtained. However, it is not inferior in nonwoven fabric processability such as card passing property and bulk recovery. Moreover, you may perform an annealing process in atmospheres, such as 90-120 degreeC dry heat, wet heat, and steam, before and after the said extending | stretching as needed.

  Next, before or after applying the fiber treatment agent as necessary, a crimp of 5/25 mm or more and 25/25 mm or less is performed using a known crimping machine such as a stuffer box type crimping machine. Give. The crimped shape after passing through the crimper may be a serrated crimp and / or a corrugated crimp. When the number of crimps is less than 5 pieces / 25 mm, the card passing property tends to deteriorate, and the initial volume and bulk recoverability of the nonwoven fabric tend to deteriorate. On the other hand, when the number of crimps exceeds 25 pieces / 25 mm, the number of crimps is too large, so the card passing property is lowered, and not only the formation of the nonwoven fabric is deteriorated, but also the initial volume of the nonwoven fabric tends to be reduced. .

  Furthermore, after providing crimp with the said crimper, it is good to give an annealing process in the atmosphere of 90-120 degreeC dry heat, wet heat, or steam. Specifically, after applying the fiber treating agent, crimping is performed with a crimping machine, and the drying process is performed simultaneously with the annealing process in a dry heat atmosphere at 90 to 120 ° C., thereby simplifying the process. Can do. When the annealing treatment is performed at 90 ° C. or higher, the dry heat shrinkage rate is not increased, and a predetermined actual crimp is easily obtained, the formation of the resulting nonwoven fabric is not disturbed, and the productivity can be improved.

  The manifest crimped conjugate fiber obtained by the above method has at least one kind of crimp selected from wave-shaped crimps and spiral crimps as shown in FIG. 2, and the number of crimps is 5/25 mm. As mentioned above, since it is 25 pieces / 25 mm or less, a bulky nonwoven fabric can be obtained without reducing card passage property, and it is preferred. And it cut | disconnects to desired fiber length, and an actual crimpable composite fiber is obtained. A more preferable number of crimps is 10-20 pieces / 25 mm.

  In addition, the above-described actual crimpable conjugate fiber is manifested by manifesting at least one type of three-dimensional crimp selected from a wave-shaped crimp and a spiral crimp by manifesting a crimp in the composite fiber, and manifesting it by manifesting it. have. In the state of the fiber, it may be an actual crimp in which a three-dimensional crimp has been fully developed, or an apparent crimp that has left a slight occurrence of crimp (which produces crimp when heat is applied to the fiber). May be. However, when heat is applied to the fibers (for example, when a temperature to be processed into a nonwoven fabric described later is applied), if the number of crimps exceeds 25/25 mm, the card passing property may be reduced. Yes, not preferred.

  2ndly, the manufacturing method of the latent crimpable conjugate fiber which is another form of the crimpable conjugate fiber of this invention is demonstrated.

  First, a first component containing polybutene-1 and an ethylene-ethylenically unsaturated carboxylic acid copolymer, a polymer having a melting peak temperature 20 ° C. higher than the melting peak temperature of polybutene-1, or a melting start temperature A second component which is a polymer having a temperature of 120 ° C. or higher is prepared. In addition, in a 1st component, an ethylene-ethylenically unsaturated carboxylic acid copolymer is 5-20 mass% with respect to a 1st component. Next, in the fiber cross section, the first component occupies at least 20% of the surface of the composite fiber, and the center of gravity of the second component is displaced from the center of gravity of the composite fiber, for example, an eccentric core-sheath type composite The first component and the second component are supplied to the nozzle, the second component is melt-spun at a spinning temperature of 240 to 330 ° C., the first component is melted at a spinning temperature of 200 to 300 ° C., and taken up at a take-up speed of 100 to 1500 m / min. Get the filament. Next, the stretching temperature is set to a temperature not lower than the glass transition point of the second component and lower than the melting point of the first component, and a stretching treatment is performed at a stretching ratio of 1.5 times or more. A more preferable lower limit of the stretching temperature is a temperature 10 ° C. higher than the glass transition point of the second component. A more preferable upper limit of the stretching temperature is 90 ° C. If the stretching temperature is lower than the glass transition point of the second component, the crystallization of the first component is difficult to proceed, so that thermal shrinkage tends to increase or the bulk recovery property tends to decrease. If the stretching temperature is equal to or higher than the melting point of the first component, the fibers tend to be fused. A more preferable lower limit of the draw ratio is 2 times. A more preferable upper limit of the draw ratio is 4 times. When the draw ratio is 1.5 times or more, the draw ratio is not too low, and when heat-treated, there is a tendency that crimps are likely to appear, the initial bulk and the rigidity of the fiber itself are not reduced, card passing properties, etc. The nonwoven fabric processability and bulk recovery are not inferior.

  Next, before or after applying the fiber treatment agent as necessary, a crimp of 5/25 mm or more and 25/25 mm or less is performed using a known crimping machine such as a stuffer box type crimping machine. Give. If the number of crimps is less than 5 pieces / 25 mm, or the number of crimps exceeds 25 pieces / 25 mm, the card passing property may be deteriorated.

  Furthermore, after providing crimps with the above crimper, an annealing treatment is performed in an atmosphere of dry heat, wet heat, or steam at 50 to 90 ° C., preferably 60 to 80 ° C., more preferably 60 to 75 ° C. Good. Specifically, after applying the fiber treating agent, crimping is performed with a crimping machine, and the drying process is performed simultaneously with the annealing process in a dry heat atmosphere of 50 to 90 ° C., thereby simplifying the process. This is preferable. By setting the annealing temperature to 50 to 90 ° C., a desired heat shrinkage rate can be obtained, and a latent crimpable conjugate fiber that exhibits steric crimps when heat-treated can be obtained. Moreover, the fiber with high card | curd permeability can be obtained.

  The fiber structure of the present invention contains at least 30% by mass of the crimped conjugate fiber. When the crimped conjugate fiber is contained in an amount of 30% by mass or more, the elasticity and bulk recoverability of the fiber structure can be maintained high. Examples of the fiber structure include a knitted fabric and a nonwoven fabric (hereinafter also simply referred to as a nonwoven fabric).

  Examples of the fiber web form constituting the nonwoven fabric of the present invention include a parallel web, a semi-random web, a random web, a cross lay web, a Chris cross web, and an air lay web. The said fiber web exhibits a still higher effect, when a 1st component adhere | attaches by heat processing. The fiber web may be subjected to a needle punching process or a hydroentanglement process as necessary before thermal processing. The thermal processing means is not particularly limited as long as the crimped conjugate fiber of the present invention is sufficiently exerted, such as a hot air through heat treatment machine, a hot air up-and-down heat treatment machine, and an infrared heat treatment machine. It is preferable to use a heat treatment machine that does not require much pressure such as wind pressure.

  Further, the fiber that can be blended with the fiber web using the crimped conjugate fiber of the present invention (hereinafter also referred to as mixed fiber) is not particularly limited as long as it does not lose the performance of the crimped conjugate fiber of the present invention. Not. For example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, single fiber of polyester such as polylactic acid, low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, or of these polyolefins Copolymers of monomers, or single fibers of polyolefin such as polyolefin using a metallocene catalyst (also referred to as Kaminsky catalyst) when polymerizing these polyolefins, nylon 6, nylon 66, nylon 11, nylon 12, etc. Engineering fiber such as polyamide single fiber, (poly) acrylic single fiber made of acrylonitrile, polycarbonate, polyacetal, polystyrene, cyclic polyolefin, etc. Mention may be made of a single fiber of the stick. Here, “single fiber” refers to a fiber composed of only one kind of polymer component. Moreover, as said mixed fiber, the composite fiber containing at least 1 or more types of polymer component can also be used in the range which does not lose the performance of the crimpable composite fiber of this invention. Examples of the composite fiber include a composite fiber obtained by combining different types of resins such as polyester, polyolefin, polyamide, engineering plastic, or resins (for example, polyethylene terephthalate and polytrimethylene terephthalate) made of the same type of different polymer components. Is mentioned. In the above-mentioned composite fiber, the composite state is not particularly limited, and the cross-sectional shape in the fiber cross section is a core-sheath type composite fiber, an eccentric core-sheath type composite fiber, a parallel type composite fiber, and a citrus tufted resin component are alternately arranged. It may be a split type composite fiber or a sea-island type composite fiber. Among these, it is preferable to use a polyester single fiber or a polyester composite fiber as the mixed fiber. When the fiber web containing 30% by mass or more of the crimped conjugate fiber and 20% by mass or more of the polyester single fiber or the polyester conjugate fiber is heat-processed at 150 ° C. to 220 ° C., it has excellent thermal adhesiveness, A nonwoven fabric excellent in bulk recovery and cushioning properties can be obtained.

  The fiber web containing the crimped conjugate fiber of the present invention can be made into a bulky fiber structure by performing heat processing even in a single layer state, but the fiber web is laminated before performing heat processing. By laminating the fiber structure after the web or heat processing to obtain a laminate of the fiber structure, a fiber structure having more excellent bulkiness can be easily obtained. Moreover, in the said fiber structure, it is preferable that the fiber which comprises a fiber structure is arranged in parallel with the thickness direction of a fiber structure, in other words, is arranged in the vertical direction of a fiber structure. This is because when the fibers constituting the fiber structure are arranged in parallel to the thickness direction, good bulk recovery and cushioning properties can be obtained with respect to the pressure applied to the thickness direction. In the present invention, the fibers constituting the fiber structure are arranged in parallel to the thickness direction of the fiber structure (arranged in the longitudinal direction of the fiber structure). It means that the acute angle made with the thickness direction is 45 ° or less. And it is more preferable that 80% or more of the total number of all the constituent fibers of the fiber structure is arranged in the longitudinal direction of the fiber structure. As described above, as the fiber structure in which the fibers constituting the fiber structure are arranged in parallel to the thickness direction, the fiber web is formed into a corrugated shape and thermally bonded while being compressed in the length direction. Nonwoven fabrics (so-called stretched nonwoven fabrics) can be mentioned, but are not limited thereto.

  When the crimped conjugate fiber contained in the fiber web is the manifest crimped conjugate fiber, the heat processing temperature of the fiber web is the wave-like crimp and / or the spiral crimp of the crimped conjugate fiber that is expressed. What is necessary is just to set to the temperature range in which shrinkage | contraction does not lose | disappear at the time of heat processing, for example, when the melting peak temperature of polybutene-1 is set to Tm, it is less than the melting peak temperature of 2nd component, Preferably Tm- 10 (° C.) to Tm + 80 (° C.). By the heat processing, at least one resin component contained in the first component of the manifest crimpable conjugate fiber is melted, and the constituent fibers are thermally fused. In particular, when at least polybutene-1 of the above-described actual crimpable conjugate fiber is melted and the constituent fibers are heat-sealed, a stronger intersection between the fibers can be formed, and the bulk recoverability is increased, which is preferable. . Furthermore, when using a single fiber of polyester, for example, a single fiber made of polyethylene terephthalate, as the other mixed fiber of the fiber web, a non-woven fabric excellent in thermal adhesiveness by heat processing at 180 ° C. to 220 ° C. Is obtained.

  When the crimped conjugate fiber contained in the fiber web is the latent crimped conjugate fiber, it may be set to a temperature range in which crimp is expressed. For example, when the melting peak temperature of polybutene-1 is Tm, It is preferable to set in the range of Tm-10 (° C) to less than the melting point of the second component, preferably Tm-10 (° C) to Tm + 60 (° C). Through heat processing, at least one resin component contained in the first component of the latent crimpable conjugate fiber is melted, and the constituent fibers are heat-sealed. In particular, when at least polybutene-1 of the latent crimpable conjugate fiber is melted and the constituent fibers are heat-sealed, it is possible to form a stronger intersection between the fibers, which increases the bulk recovery and is preferable. . Furthermore, when using a single fiber of polyester, for example, a single fiber made of polyethylene terephthalate, as the other mixed fiber of the fiber web, a non-woven fabric excellent in thermal adhesiveness by heat processing at 180 ° C. to 220 ° C. Is obtained. In particular, when the crimped conjugate fiber of the present invention is heat-processed at a high temperature in the range of 180 ° C. to 220 ° C., the adhesive strength tends to increase as the heat processing temperature increases. This is because, in the crimped conjugate fiber of the present invention, since the first component contains a predetermined amount of an ethylene-ethylenically unsaturated carboxylic acid copolymer in addition to polybutene-1, no adhesive point thinness occurs. I guess that.

  Moreover, it is preferable that the said nonwoven fabric does not fall adhesive strength also in the high temperature for heat-seal | bonding fibers, for example, the heat processing of 180 degreeC or more. Here, “adhesion strength” refers to the following measurement. First, crimped conjugate fibers are prepared and passed through a card machine to obtain a parallel card web. Next, two fiber webs are prepared and cut into a length of 150 mm and a width of 50 mm, respectively, and then the two fiber webs are overlapped with both ends in the length direction and the width direction aligned to obtain the length of the fiber web. The release paper is sandwiched between the upper and lower fiber webs so as to occupy an area of 100 mm from one end in the vertical direction and 50 mm in the width direction. As described above, the two fibrous webs in a state where the release paper is sandwiched between a part of the fibrous webs are compressed to a thickness of 5 mm and heat-treated at each thermal processing temperature for 2 minutes. Subsequently, the end of each fiber web that is not thermally bonded is attached to an attachment portion of a constant speed extension type tensile tester (Orientec Co., Ltd., “UCT-1T”), and a test speed (tensile speed) of 100 mm / The peel strength of the bonded portion is measured under the condition of min, and is defined as the bond strength of the nonwoven fabric.

  Moreover, it is preferable that the said nonwoven fabric has the compression residual strain rate measured according to A method of JIS-K-6400-4 to 45% or less. The compressive residual strain rate indicates the degree of change in the hardness of the nonwoven fabric when heated to 70 ° C. The smaller this value, the more the deterioration of the fiber or nonwoven fabric due to heat is suppressed, and the bulk recovery property is excellent. Indicates that

  Moreover, it is preferable that the said nonwoven fabric has the repetitive compression residual distortion rate measured according to B method of JIS-K-6400-4 of 10% or less. The above-mentioned repeated compression residual strain rate indicates the degree of change in the hardness of the nonwoven fabric when 50% compression is repeated 80,000 times. The smaller this value, the more the deterioration of the fiber or nonwoven fabric due to compression is suppressed. This indicates that the bulk recovery property is excellent.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

  The measurement method and evaluation method used in this example are as follows.

(Q value)
I. Analyzing device to be used (i) Cross fractionation device “CFC T-100” (hereinafter referred to as CFC) manufactured by Dia Instruments Co., Ltd.
(Ii) Fourier transform infrared absorption spectrum analysis (FT-IR), “1760X” manufactured by PerkinElmer
A fixed wavelength infrared spectrophotometer attached as a CFC detector is removed and an FT-IR is connected instead, and this FT-IR is used as a detector. The transfer line from the outlet of the solution eluted from the CFC to the FT-IR is 1 m long, and the temperature is maintained at 140 ° C. throughout the measurement. The flow cell attached to the FT-IR has an optical path length of 1 mm and an optical path diameter of 5 mmφ, and the temperature is maintained at 140 ° C. throughout the measurement.
(Iii) Gel permeation chromatography (GPC)
For the GPC column at the rear stage of the CFC, three “AD806MS” manufactured by Showa Denko KK are connected in series.

II. CFC measurement conditions (i) Solvent: orthodichlorobenzene (ODCB)
(Ii) Sample concentration: 1 mg / mL
(Iii) Injection volume: 0.4 mL
(Iv) Column temperature: 140 ° C
(V) Solvent flow rate: 1 mL / min

III. Measurement conditions of FT-IR After elution of the sample solution starts from GPC at the latter stage of the CFC, FT-IR measurement is performed under the following conditions to collect GPC-IR data.
(I) Detector: MCT
(Ii) Resolution: 8 cm ^-1
(Iii) Measurement interval: 0.2 minutes (12 seconds)
(Iv) Number of integrations per measurement: 15 times

IV. Post-processing and analysis of measurement results The molecular weight distribution is obtained using the absorbance at 2945 cm ⁻¹ obtained by FT-IR as a chromatogram. Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene. Standard polystyrenes used are “F380”, “F288”, “F128”, “F80”, “F40”, “F20”, “F10”, “F4”, “F1”, “F1”, manufactured by Tosoh Corporation. A5000 "," A2500 ", and" A1000 ". A calibration curve is prepared by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL dibutylhydroxytoluene (BHT)) so that each is 0.5 mg / mL. The calibration curve uses a cubic equation obtained by approximation by the least square method. Conversion to molecular weight uses a general-purpose calibration curve with reference to “Size Exclusion Chromatography” written by Sadao Mori (Kyoritsu Shuppan). The following numerical values are used for the viscosity equation ([η] = K × Mα) used at that time.
(I) Calibration curve using standard polystyrene K = 0.000138, α = 0.70
(Ii) Polypropylene sample measurement: K = 0.000103, α = 0.78

  In addition, in the above, it measures by GPC (gel permeation chromatography), but when measuring by another model, it is described in 2005 plastic molding material business manual (Chemical Industry Daily, published on August 30, 2004). As described above, measurement can be performed simultaneously with “MG03B” manufactured by Nippon Polypro Co., Ltd., and the value when MG03B indicates 3.5 can be used as the blank condition, and the measurement can be performed by adjusting the condition.

(Uniformity of composite fiber)
The fiber cross section of the crimped conjugate fiber was observed with an optical microscope (MORITEX, “SCOPEMAN 503”), and the uniformity of the conjugate fiber was evaluated according to the following criteria.
A: There is neither fineness variation nor volume variation of the sheath component.
B: Although there is unevenness in fineness, there is no volume unevenness of the sheath component.
C: There is considerable unevenness in fineness, and there is also a little unevenness in volume of the sheath component.
D: Both fineness unevenness and sheath component volume unevenness are large.

(Spinnability (thread breakage))
The spinnability (yarn breakage) of the crimped conjugate fiber was evaluated by the number of yarn breaks that occurred during melt spinning of 1000 kg of crimped conjugate fiber. The evaluation criteria are as follows.
A: The yarn breakage is 5 times / 1000 kg or less.
B: The yarn breakage is 10 times / 1000 kg or less.
C: The yarn breakage is 50 times / 1000 kg or less.
D: Yarn breakage occurs frequently and cannot be picked up.

(Spinning fusion)
The spin fusion of crimped conjugate fibers was evaluated according to the following criteria.
A: There is no spinning fusion.
B: There is a little spun fusion.
C: There is considerable spinning fusion.
D: Very much spun fusion.

(Adhesive strength)
First, the crimped conjugate fibers of Examples and Comparative Examples were respectively prepared and passed through a card machine to obtain a parallel card web having a basis weight of 50 g / m ² . Next, two fiber webs were prepared and cut into a length of 150 mm and a width of 50 mm, respectively. Subsequently, the two fibrous webs are overlapped with both ends in the length direction and the width direction, and the release paper is placed so as to occupy an area of 100 mm from one end and 50 mm in the width direction in the length direction of the fiber web. Laminate between upper and lower fiber webs. By carrying out like this, the area | region of 50 mm and width 50mm is thermally bonded from the other end of the length direction of the fiber web in which the release paper does not exist between the upper and lower fiber webs by the heat processing mentioned later. Then, as described above, the two fiber webs were compressed to a thickness of 5 mm in a state where the release paper was sandwiched between a part of the fiber webs and heat-treated at each heat processing temperature for 2 minutes. Subsequently, the end of each fiber web that is not thermally bonded is attached to the attachment portion of a constant speed extension type tensile tester (Orientec Co., Ltd., “UCT-1T”) at a position 10 mm from the end, and the test speed is set. (Tensile speed) The peel strength of the bonded portion was measured under the condition of 100 mm / min to obtain the bond strength of the nonwoven fabric. In addition, it measured at least 3 times and the average value was made into the value of adhesive strength.

(Compressive residual strain rate)
According to A method of JIS-K-6400-4, the strain rate after compression for 22 hours was measured at a temperature of 70 ° C. ± 1 ° C. and a compression rate of 50%, and was defined as a compression residual strain rate. In addition, all thickness measurements were made under no caustic.

(Repeated compression residual strain rate)
According to B method of JIS-K-6400-4, the strain rate after 80,000 compressions was measured at 23 ° C. and a compression rate of 50%, and was set as a repeated compression residual strain rate. In addition, all thickness measurements were made under no caustic.

The polymers used in this example are as follows.
(A) PET (“T200E” manufactured by Toray Industries, Inc., melting peak temperature (melting point): 255 ° C., IV value: 0.64)
(B) PTT (“CORTERRA 9200” manufactured by Shell Chemicals Japan, Inc., melting peak temperature (melting point): 228 ° C., IV value: 0.92)
(C) PP (Nippon Polypro Co., Ltd. “SA01A”, melting peak temperature (melting point): 160 ° C., MFR230: 10, Q value: 3.2)
(D) PB-1 (“PB0400” manufactured by Sun Allomer Co., Ltd., melting peak temperature (melting point): 123 ° C., MFR 190: 20)
(E) EMAA (“Nucleel AN4213C” manufactured by Mitsui DuPont Polychemical Co., Ltd., methacrylic acid content: 11 mass%, melting peak temperature (melting point): 88 ° C., MFR 190: 10, softening temperature: 62 ° C.) did.

  In the above, IV is the intrinsic viscosity. MFR230 is a melt flow rate measured at 230 ° C. and 21.18 N (2.16 kgf) according to JIS-K-7210. Moreover, MFR190 is the melt flow rate measured by 190 degreeC and 21.18N (2.16kgf) according to JIS-K-7210.

Hereinafter, the manufacturing conditions of the crimped conjugate fiber will be described.
(A) Extrusion temperature: The second component was 280 ° C., the first component was 250 ° C., and the nozzle cap temperature was 270 ° C.
(B) Number of nozzle holes: 600 holes (C) Composite ratio: Core / sheath = 55/45 (volume ratio)
(D) Unstretched fineness: 8 dtex
(E) Stretching temperature: wet 70 ° C
(F) Stretch ratio: 2.3 times (G) Crimp: 12-15 pieces / 25 mm
(H) Annealing temperature (drying temperature), time: 110 ° C., 15 minutes (I) Product fineness (single fiber): 4.4 dtex
(J) Fiber length: 51 mm

(Examples 1-6 and Comparative Examples 1 and 2)
Using the first component and the second component having the composition components and blending ratios shown in Table 1 below, the wrinkles of Examples 1 to 6 and Comparative Examples 1 and 2 under the production conditions for the crimped conjugate fiber described above A shrinkable conjugate fiber was produced. Table 1 below shows the results of the eccentricity, fiber cross section, spinnability (thread breakage), and spin fusion of the obtained crimped conjugate fibers of Examples 1 to 6 and Comparative Examples 1 and 2. In Examples 1 to 6 in which the crimpable conjugate fiber is a combination of the first component and the second component shown in Table 1, a single fiber consisting only of polybutene-1 or a conjugate where the first component is only polybutene-1 There was no problem related to the spinnability, which makes it impossible to take off the fiber when spinning, and undrawn fibers could be obtained in any of the examples. Moreover, there was no problem in processability even in the drawing step, and crimped conjugate fibers comprising combinations of the respective resin components were obtained. In addition, all the composite fibers of Examples 1 to 6 developed the wavy crimp shown in FIG. 2A, and the number of crimps was 16/25 mm.

  As can be seen from the results in Table 1, in the crimped conjugate fibers of Examples 1 to 6 containing polybutene-1 as the first component and the second component consisting of polyester, the ethylene-ethylenically unsaturated carboxylic acid is added to polybutene-1. By adding an acid copolymer, the difficulty of spinning and difficulty of polybutene-1 were eliminated. In particular, when both the ethylene-ethylenically unsaturated carboxylic acid copolymer and polypropylene were added to polybutene-1 in the first component, the effect was remarkable.

(Example 7)
50% by mass of the crimped conjugate fiber of Example 1 and 50% by mass of PET single fiber (single fiber fineness: 7.8 dtex) were mixed and applied to a parallel card to prepare a card web having a basis weight of 50 g / m ^2. And cut to a length of 150 mm and a width of 50 mm. Subsequently, the two card webs were overlapped with a release paper sandwiched between regions having a length of 100 mm and a width of 50 mm, compressed to a thickness of 5 mm, and using a hot air circulation type heat treatment machine, the following Table 2 The first component was heat-sealed for 2 minutes at each heat processing temperature shown in FIG.

(Examples 8 to 12 and Comparative Examples 3 and 4)
Nonwoven fabrics of Examples 8 to 12 and Comparative Examples 3 and 4 were obtained in the same manner as Example 7 except that the crimped conjugate fibers of Examples 2 to 6 and Comparative Examples 1 and 2 were used.

  The adhesive strengths of the nonwoven fabrics of Examples 7 to 12 and Comparative Examples 3 and 4 obtained above were measured as described above, and the results are shown in Table 2 below.

(Examples 13 to 18)
In each case, 100% by mass of the crimped conjugate fiber of Examples 1 to 6 was put on a parallel card to produce a card web having a basis weight of 600 g / m ² , then compressed to a thickness of 25 mm, and using a hot air circulation type heat treatment machine. The first component was heat-sealed at 190 ° C. for 4 minutes to obtain nonwoven fabrics of Examples 13 to 18.

(Comparative Examples 5 and 6)
The nonwoven fabrics of Comparative Examples 5 and 6 were obtained in the same manner as in Example 13 except that the crimped conjugate fibers of Comparative Examples 1 and 2 were used.

(Example 19)
50% by mass of the crimped conjugate fiber of Example 1 and 50% by mass of PET single fiber (single fiber fineness of 7.8 dtex) were put on a parallel card to produce a card web having a basis weight of 600 g / m ² , and then a thickness of 25 mm. The first component was heat-sealed at 190 ° C. for 4 minutes using a hot air circulation type heat treatment machine to obtain a nonwoven fabric of Example 19.

(Examples 20 to 24 and Comparative Examples 7 and 8)
The nonwoven fabrics of Examples 20 to 24 and Comparative Examples 7 and 8 were obtained in the same manner as Example 19 except that the crimped conjugate fibers of Examples 2 to 6 and Comparative Examples 1 and 2 were used.

  The repeated compressive residual strain ratio and compressive residual strain ratio of the nonwoven fabrics of Examples 13 to 24 and Comparative Examples 5 to 8 obtained above were measured as described above, and the results are shown in Table 3 below.

  Moreover, the state of the adhesion point of the constituent fiber after the heat processing in the nonwoven fabric was cut in a direction perpendicular to the length direction of the crimped conjugate fiber using a scanning electron microscope (“S-3500N” manufactured by Hitachi, Ltd.). The cut surface of the nonwoven fabric was photographed with a magnification of 70 times and observed. 5 and 6 show scanning electron micrographs (hereinafter also referred to as SEM photographs) taken as described above in Example 19 and Comparative Example 7, respectively.

  From FIG. 5, in the nonwoven fabric of Example 19, the crimped conjugate fiber of the present invention constituting the nonwoven fabric after heat processing is free from variations (unevenness) in the fineness (thickness) and peeling, and the fibers It was confirmed that the intersections of each other adhered firmly and that no adhesion points or thinning occurred. Although not shown, the same applies to the nonwoven fabrics of other examples. In the nonwoven fabric of this invention, the crimpable conjugate fiber of this invention which comprises a nonwoven fabric contains the 1st component which added the ethylene-ethylenically unsaturated carboxylic acid copolymer to polybutene-1, Therefore A 1st component is As a result of the melt viscosity being increased when melted, the melted resin tends to stay in the vicinity, resulting in a composite due to deviations in the component interface between the first component and the second component, which can occur by heating, particularly heat processing at high temperatures It is presumed that variations in fiber fineness and peeling are suppressed. Further, it is presumed that the melted resin stays at the intersection of the fibers as described above, and as a result, the fibers are strongly thermally bonded to each other and no adhesion point is generated.

  On the other hand, as can be seen from FIG. 6, in the nonwoven fabric of Comparative Example 7, the fineness unevenness occurred in the composite fiber constituting the nonwoven fabric after heat processing, and the fiber surface was uneven. Moreover, the adhesion point thinness has generate | occur | produced in the adhesion point of fibers. Although not shown, the same applies to the nonwoven fabrics of other comparative examples. In the nonwoven fabric of the comparative example, since the first component of the composite fiber constituting the nonwoven fabric does not contain an ethylene-ethylenically unsaturated carboxylic acid copolymer, the component interface between the first component and the second component is shifted by heating, As a result, variations in fineness and peeling occur, and it is presumed that adhesion points and thinning have occurred at the intersections of the fibers.

  As can be seen from the results of Examples 7 to 12 in Table 2, the nonwoven fabric comprising the crimped conjugate fiber of the present invention as a constituent fiber has excellent thermal adhesiveness, and the adhesive strength tends to increase as the processing temperature is increased. It was. This is because, as described above, in the nonwoven fabric of the present invention, the crimpable conjugate fiber constituting the nonwoven fabric contains the first component to which the ethylene-ethylenically unsaturated carboxylic acid copolymer is added, thereby heating, particularly high processing. It is presumed that even when heat treatment is performed at a temperature, variation in fineness of composite fibers, peeling is suppressed, and adhesive points and thinning are not generated at intersections of fibers. On the other hand, as can be seen from the results of Comparative Example 3 in Table 2, a nonwoven fabric comprising crimped conjugate fibers that do not contain an ethylene-ethylenically unsaturated carboxylic acid copolymer as the first component increases the processing temperature. And the adhesive strength became smaller. This is because, as described above, in the nonwoven fabric of Comparative Example 3, by heating, particularly heat treatment at a high processing temperature, the interface between the first component and the second component deviates, resulting in variations in fineness, peeling, and It is presumed that an adhesive point has become thin at the intersection.

  Moreover, as can be seen from the results in Table 3, the nonwoven fabrics of Examples 13 to 18 consisting of 100% by mass of the crimpable conjugate fibers of Examples 1 to 6 and 50% by mass of the crimpable conjugate fibers of Examples 1 to 6 The nonwoven fabrics of Examples 19 to 24 comprising 50% by mass of PET single fiber had a repeated compression residual strain ratio of 10% or less, excellent durability, and excellent bulk recovery in repeated compression. Furthermore, the compressive residual strain rate of the nonwoven fabrics of Examples 13 to 24 was 40% or less, had heat resistance, and was excellent in bulk recovery at high temperatures.

  Further, as can be seen from Table 3, the nonwoven fabrics of Comparative Examples 6 and 8 using the crimped conjugate fiber of Comparative Example 2 containing 25% by mass of an ethylene-ethylenically unsaturated carboxylic acid copolymer. The repeated compressive residual strain rate exceeded 10%, and the compressive residual strain rate exceeded 45%, and both durability and heat resistance were inferior. In addition, in the nonwoven fabrics of Comparative Examples 6 and 8 in which the crimped conjugate fiber of Comparative Example 2 is a constituent fiber, the nonwoven fabric (Comparative Example 6) composed only of the crimped conjugate fiber of Comparative Example 2 is another nonwoven fabric. Compared to the above, the compression residual strain rate and the compression residual strain rate were particularly high. This is because the content of the ethylene-ethylenically unsaturated carboxylic acid copolymer of the first component is too large, and the soft ethylene-ethylenically unsaturated carboxylic acid copolymer strongly affected the physical properties of the whole nonwoven fabric. It is considered a thing.

  The nonwoven fabric using the crimped conjugate fiber of the present invention is superior in both initial bulk and bulk recovery properties compared with a nonwoven fabric made of a conjugate fiber using a conventional elastomer. It is preferably used for low density nonwoven products such as packaging materials, cosmetic materials, female bra pads, shoulder pads and the like.

The fiber cross section of the crimpable conjugate fiber in one Embodiment of this invention is shown. The crimp form of the crimpable conjugate fiber in one embodiment of the present invention is shown. The form of the conventional machine crimp is shown. The crimped composite fiber of the present invention shows a crimped form in which wavy crimps and serrated crimps are mixed. It is a SEM photograph of the cut surface cut | disconnected in the direction perpendicular | vertical to the length direction of the crimpable conjugate fiber in the nonwoven fabric of Example 19 of this invention. It is a SEM photograph of the cut surface cut | disconnected in the direction perpendicular | vertical to the length direction of the crimpable conjugate fiber in the nonwoven fabric of the comparative example 7 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st component 2 2nd component 3 Center of gravity position of 2nd component 4 Center of gravity position of composite fiber 5 Radius of composite fiber 10 Composite fiber 11 Adhesion point in which adhesion point does not generate | occur | produce 12 Adhesion in which adhesion point thinness has generate | occur | produced Point 13 Unevenness (unevenness on the fiber surface) generated on the surface of the constituent fiber

Claims (10)

A composite fiber comprising a first component and a second component,
The first component includes polybutene-1 and an ethylene-ethylenically unsaturated carboxylic acid copolymer, and the ethylene-ethylenically unsaturated carboxylic acid copolymer is 5 to 20 mass based on the first component. %
The second component is a polymer having a melting peak temperature that is 20 ° C. or more higher than the melting peak temperature of polybutene-1, or a polymer having a melting start temperature of 120 ° C. or more,
In the fiber cross section, the first component occupies at least 20% of the surface of the composite fiber, and the center of gravity of the second component is deviated from the center of gravity of the composite fiber,
The crimped conjugate fiber, wherein the conjugate fiber is an actual crimp that exhibits a three-dimensional crimp or a latent crimp that exhibits a three-dimensional crimp when heated.   The ethylene-ethylenically unsaturated carboxylic acid copolymer is at least selected from the group consisting of an ethylene-acrylic acid copolymer, an ethylene-methacrylic acid copolymer, an ethylene-maleic acid copolymer, and an ionomer thereof. The crimpable conjugate fiber according to claim 1, which is one.   The first component further contains polypropylene, and the first component contains 60 to 94% by mass of the polybutene-1, 1 to 20% by mass of the polypropylene, and the ethylene-ethylenically unsaturated carboxylic acid copolymer. The crimped conjugate fiber according to claim 1 or 2, comprising 5 to 20% by mass.   The blend ratio of the polypropylene and the ethylene-ethylenically unsaturated carboxylic acid copolymer contained in the first component is, by mass ratio, polypropylene: ethylene-ethylenically unsaturated carboxylic acid copolymer = 1: 2 to 12: 5. The crimpable conjugate fiber according to claim 3, wherein   An eccentric core sheath in which the first component is disposed as a sheath component of a composite fiber, the second component is disposed as a core component, and the center of gravity of the second component is shifted from the center of gravity of the composite fiber in a fiber cross section The crimpable conjugate fiber according to any one of claims 1 to 4, which has a structure.   The crimpable conjugate fiber according to any one of claims 1 to 5, wherein the second component is polyester.   A fiber structure comprising at least 30% by mass of the crimped conjugate fiber according to any one of claims 1 to 6.   The fiber structure further includes 20 to 20% of a single fiber composed of a single polymer component selected from a polymer group consisting of polyester, polyolefin, polyamide, and polyacrylonitrile, or a composite fiber containing at least one polymer component selected from the polymer group. The fiber structure according to claim 7, containing 70% by mass.   The fiber structure according to claim 7 or 8, wherein at least one resin component contained in the first component of the crimped conjugate fiber is melted and the constituent fibers of the fiber structure are thermally fused.   The fiber structure according to any one of claims 7 to 9, wherein fibers constituting the fiber structure are arranged so as to be parallel to a thickness direction of the fiber structure.

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