JP2007126806A - Crimping conjugate fiber and non-woven fabric using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crimping conjugate fiber capable of obtaining a non-woven fabric excellent in heat resistance, showing less bulk reduction on heat-processing, and having a large initial bulk and bulk recover. <P>SOLUTION: The conjugate fiber contains a first component and second component, the first component contains 60-95 mass% polybutene-1 and 5-40 mass% polypropylene, the second component is a polymer having a melting point higher than that of the polybutene-1 by ≥20°C, the first component occupies at least 20% of the conjugate fiber surface and the position of center of gravity of the second component is deviated from the position of center of the gravity of the conjugate fiber when viewed from a cross section of the conjugate fiber, and the conjugate fiber is the crimping conjugate fiber having at least one kind of crimp selected from a wave-formed crimp and spiral crimp. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  In various applications such as sanitary materials, packaging materials, non-woven fabrics used for wet tissues, filters, wipers, etc., non-woven fabrics used for hard cotton, chairs, etc., molded products, at least a part of the low melting point component is exposed on the fiber surface. The heat-bonding nonwoven fabric using the heat-fusible composite fiber composed of the high-melting-point component having a higher melting point than the low-melting-point component is used, and in particular, the fiber is excellent in bulk elasticity of the nonwoven fabric, that is, the bulk recovery property in the thickness direction. The demand is growing as a substitute for urethane foam. The reason why there is a great demand as a substitute for urethane foam is that it is difficult to handle chemicals used in production, chlorofluorocarbons are discharged, and disposal is difficult. In addition, the properties of the urethane foam obtained include problems that it feels hard in the initial stage of compression, poor air permeability and is easily steamed, insufficient sound absorption, and easily yellowing. is there. Accordingly, various studies have been made on nonwoven fabrics having excellent bulk recovery properties.

  The following cited references 1 and 2 propose a composite fiber composed of a polyester component having a melting point of 200 ° C. or higher and a polyether ester block copolymer component having a melting point of 180 ° C. or lower, so-called elastomer component. By using an elastomer component as the sheath component, when subjected to compression deformation, the degree of freedom of the bonded portion and the durability are improved, so that the bulk recoverability is excellent.

Citation 3 below is composed of a first component containing a polytrimethylene terephthalate polymer and a second component containing a polyolefin 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. Proposed composite fiber. As the first component, a polymer having high bending elasticity and low bending hardness is used, and further, the fiber cross section is decentered and the crimped shape is corrugated, so that the bulk recovery is excellent and flexible. A nonwoven fabric having a large initial bulk is obtained.
JP-A-4-240219 JP-A-5-247724 JP 2003-3334 A

  In the cited references 1 and 2, a polyester ether elastomer is used for the sheath component, and since this polymer has rubber-like elasticity and a large degree of freedom in deformation of the adhesion point, a nonwoven fabric excellent in bulk recovery will be obtained. It is said. However, this polyester ether elastomer is a copolymer of hard polyester and soft ether, and since it contains a soft component, it is easily softened by heat (because heat resistance is low), and the bulk of the nonwoven fabric is reduced during heat processing. So-called sag occurs. As a result, the composite fiber using the polyester ether elastomer as the sheath component has a problem that the initial volume when made into a non-woven fabric is small, only a high-density non-woven fabric is obtained, and the use is limited. In addition, the nonwoven fabric after being compressed in a heated state or after being repeatedly compressed is the original nonwoven fabric such that the bonding point between the fibers and the fibers themselves are broken, bent, fiber strength is reduced, etc. In comparison, there was a problem that the nonwoven fabric hardness was greatly reduced.

  In the cited document 3, the core polymer and the fiber cross-section are specified, and the crimped state is specified, thereby obtaining a nonwoven fabric excellent in bulk recoverability. Although the nonwoven fabric has a large thickness (initial volume), the bulk recovery property, particularly the initial bulk recovery property immediately after dewetting, is not sufficient, and there is a problem that the application is limited.

  Therefore, in the prior art, a nonwoven fabric fiber having a large initial bulk (low density) and excellent bulk recoverability has not been obtained.

  In order to solve the above-mentioned conventional problems, the present invention uses a crimped conjugate fiber excellent in heat resistance, small in bulk reduction (sagging) during thermal processing, and capable of obtaining a nonwoven fabric having a large initial bulk, and the same. Provide a nonwoven fabric.

  The crimpable conjugate fiber of the present invention is a conjugate fiber containing a first component and a second component, and the first component comprises 60 to 95% by mass of polybutene-1 and 5 to 40% by mass of polypropylene. The second component is a polymer having a melting point 20 ° C. higher than the melting point of polybutene-1, and the first component occupies at least 20% of the surface of the composite fiber when viewed from the fiber cross section. The centroid position of the second component is deviated from the centroid position of the composite fiber, and the composite fiber has at least one kind of crimp selected from a wave crimp and a spiral crimp. And

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

  The crimpable conjugate fiber of the present invention is selected from polybutene-1 as the first component, and further blended with polypropylene (PP) that is highly compatible with polybutene-1 (PB-1), so that spinnability and stretching are achieved. The nonwoven fabric excellent in initial bulk and bulk recoverability can be obtained.

  The nonwoven fabric using the crimped conjugate fiber of the present invention is superior in both initial bulk and bulk recovery compared to a nonwoven fabric made of a composite fiber using a conventional elastomer. It can also be used in low density nonwoven products such as materials, filters, cosmetic materials, women's bra pads, shoulder pads and the like. Furthermore, the nonwoven fabric using the crimped conjugate fiber of the present invention is excellent in bulk recovery at high temperatures (for example, about 60 to 90 ° C.), and is used in fields requiring heat resistance, such as vehicle cushion materials, It can be used as a backing material for flooring flooring.

  The crimped conjugate fiber of the present invention uses polybutene-1 (PB-1) as the first component (for example, a sheath adhesive component). Although this polymer is relatively soft, it does not contain a soft component like an elastomer, and is excellent in heat resistance. Therefore, a bulk reduction (sagging) during heat processing is small, and a nonwoven fabric having a large initial bulk is obtained. In addition, PB-1 has a certain degree of flexibility and shape maintainability (return to deformation) like the elastomer, so that the adhesion point at the time of compression is deformed, and further excellent in recoverability against deformation and bulk recoverability. An excellent nonwoven fabric is obtained.

  However, PB-1 has a polymer characteristic that it has a high molecular weight, and has a low degree of freedom in molecular chains, so it is difficult to stretch by stretching and easily causes stretching troubles. Moreover, since the heat shrinkability is very large, the fibers shrink during heat processing, and it is difficult to obtain a good nonwoven fabric. Further, since the rate of decrease in viscosity with respect to temperature is larger than that of other polymers, it is necessary to raise the spinning temperature especially when a high melting point (for example, polyester) is used as the core polymer. There is a problem that the viscosity of the fiber is not stable and it is difficult to obtain uniform fibers. Moreover, since the melting point of PB-1 is relatively low at about 120 ° C., there was a problem in bulk recovery when used at a high temperature of about 70 ° C.

  As a result of various studies, it has been found that all of the stretchability, heat shrinkability, and melt viscosity instability can be solved by adding a small amount of polypropylene (PP) to PB-1.

  Specifically, 60 to 95% by mass of polybutene-1 and 5 to 40% by mass of polypropylene are used as the first component of the composite fiber. The first component is disposed, for example, in a composite fiber sheath.

  As the second component of the composite fiber, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polypropylene (PP) or the like whose melting point is higher than that of the sheath is used. The second component is disposed, for example, on the core of the composite fiber.

  The fiber cross-sectional shape is an eccentric cross-section in which the gravity center position of the second component is shifted from the fiber gravity center position, and is a wave shape and / or a helical crimp. Thereby, it becomes easy to enlarge the initial volume of the nonwoven fabric, and further, a spring effect can be exhibited during compression, and a nonwoven fabric excellent in bulk recoverability can be obtained.

  Hereinafter, more preferable examples will be described. First, PB-1 used in the present invention preferably has a melting peak temperature in the range 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 in the range of 115 to 130 ° C., the heat resistance is high, and the bulk recoverability at high temperatures is good.

  The melt index (MI; measurement temperature 190 ° C., load 2.16 kgf (21.18 N)) according to JIS-K-7210 of PB-1 is preferably in the range of 1 to 30 g / 10 minutes. More preferable MI is 3 to 25 g / 10 min, and even more preferable is 3 to 20 g / 10 min. When the MI is in the range of 1 to 30 g / 10 minutes, the high molecular weight of PB-1 is obtained, and therefore, heat resistance is good, and bulk recovery property when temperature is applied is preferable. Further, the take-up property of the spinning and the stretchability are improved.

  The upper limit of the addition amount of PP is, as the addition amount is increased, the stretchability is improved, the heat shrinkability is small, and the stability of the melt viscosity is improved. . Moreover, when there is much PP addition amount, since the softness | flexibility of a polymer will worsen and the deformation | transformation freedom degree of an adhesion point will become small, bulk recovery property will worsen. Further, as the amount of PP added increases, the crystallization rate of PB-1 is inhibited, so that it cannot be cooled during take-up of the spinning, and a fused yarn is likely to be generated. Therefore, it is necessary to make it 40 mass% or less. The lower limit of the addition amount of PP is 5% by mass. If it is less than 5% by mass, there is no effect of preventing the polymer viscosity from decreasing with respect to the melting temperature. In addition, the effect of preventing heat shrinkage is small. Therefore, the addition amount of polypropylene is 5% by mass or more and 40% by mass or less, preferably 7% by mass or more and 30% by mass or less, and most preferably 10% by mass or more and 25% by mass or less. When PB-1 and PP are melt blended, both polymers are easily compatible. Further, by blending polypropylene (PP) having high compatibility with polybutene-1 (PB-1), spinnability and stretchability are improved, and single fiber heat shrinkage is reduced. That is, only PB-1 has a low melt viscosity and a too high fluidity, so the melt spinning stability is poor. However, blending PP improves the flow characteristics and enables stable and uniform spinning. Moreover, since the thermal shrinkage is large only with PB-1, the crimp becomes too fine at the time of drying treatment at around 110 ° C. after the mechanical crimping is imparted, or the area shrinkage rate is too large at the time of nonwoven fabric processing, and the texture is Although it may become a nonwoven fabric with bad initial volume and a bad bulk recovery property, this can be prevented by blending PP. In addition, the stretchability is poor with only polybutene-1, but the stretchability is improved by blending PP. As described above, polybutene-1 has a problem that it has a high molecular weight (that is, a long molecular chain) and a large amount of entanglement between molecules, which makes it difficult to stretch. It is estimated that the polybutene-1 molecular chain enters the molecular weight, and the entanglement of the polybutene-1 molecular chain is moderately suppressed.

  The PP may be a homopolymer, a random copolymer, or a block copolymer, but is preferably a homopolymer or a block copolymer in consideration of heat shrinkability. In particular, homopolymers tend to be slightly harder, but are advantageous in terms of bulk recovery and are preferred.

  The ratio (Q value) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the PP 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 high molecular weight PP is reduced, so that PP easily enters between the molecular chains of PB-1, and as a result, thermal shrinkage can be reduced.

  The addition amount of PP and the Q value of PP preferably have an addition amount / Q value ratio of 2.3 or more. More preferably, it is 2.4 or more, and most preferably 2.5 or more. The PP addition amount / Q value ratio is an index that indicates the ease with which PP enters between the molecular chains of PB-1, and is an index that affects the contractility of the fiber. When the PP addition amount / Q value is 2.3 or more, it means that the PP addition amount is large or the Q value is small, and the bulk recoverability depends on the addition amount of PB-1, and both of them. By adjusting the balance of the values, the shrinkage of the fibers can be suppressed and the bulk recoverability can be increased. For example, when the amount of PP added is small, a sufficient amount of PP enters between the PB-1 molecular chains, so that the shrinkage of the fiber tends to be small. Also, when the Q value of PP is small, it tends to enter between the molecular chains of PB-1, and the shrinkage of the fiber tends to be small. On the other hand, the upper limit of the addition amount / Q value ratio is not particularly limited, but is preferably 10 or less in consideration of suppression of shrinkage and bulk recovery of the fiber.

  The melt flow rate (MFR; measurement temperature 230 ° C., load 2.16 kgf (21.18 N)) according to JIS-K-7210 in the PP is preferably in the range of 5 to 30 g / 10 minutes. A more preferred MFR is in the range of 6-25 g / 10 min. When the MFR is in the range of 5 to 30 g / 10 minutes, the decrease in the melt viscosity of PB-1 can be suppressed, and since PP has an appropriate molecular weight for entering between the molecular chains of PB-1, As a result, uniform fibers can be obtained and thermal shrinkage can be reduced.

  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, a styrene type, etc. And other elastomers.

  The second component is preferably a polymer excellent in flexural strength and flexural elasticity, for example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid or other polyester, nylon 6, nylon 66, nylon 11, Examples thereof include polyamide such as nylon 12, polypropylene, polycarbonate, polystyrene and the like. Polyester is particularly preferable. Most preferred is polytrimethylene terephthalate (PTT).

  The PTT preferably used in the present invention may be a PTT homo resin, a PTT copolymer resin shown below, or a blend of PTT and another polyester resin, and dry heat shrinkage when a crimped conjugate fiber is used. Within a range where the desired wave shape crimp and / or spiral crimp can be obtained while keeping the rate low, acid components such as isophthalic acid, succinic acid, adipic acid, 1,4 butanediol, 1,6 hexanediol The glycol component such as polytetramethylene glycol, polyoxymethylene glycol and the like may be copolymerized in an amount of 10% by mass or less, and other polyester resins such as PET and PBT may be blended in an amount of 50% by mass or less. If the copolymerization component exceeds 10% by mass, the flexural modulus becomes small, which is not preferable. On the other hand, if the blend ratio of the other polyester resin exceeds 50% by mass, it approaches the properties of the other polyester resin blended, which is not preferable.

  The intrinsic viscosity [η] of the PTT is preferably 0.4 to 1.2. More preferably, it is 0.5 to 1.1. 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 determined based on the following formula (Equation 1) measured with an Ostwald viscometer as an o-chlorophenol solution at 35 ° C.

(However, ηr: 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. C: in 100 ml of the solution) Solute weight value in grams.)
When the intrinsic viscosity is less than 0.4, the molecular weight of the resin is too low, so that not only the spinnability is inferior, but also the fiber strength is low and the practicality is poor. When the intrinsic viscosity exceeds 1.2, the molecular weight of the resin is increased and the melt viscosity becomes too high, so that single yarn breakage or the like occurs, and good spinning becomes difficult, which is not preferable.

  It is preferable that the melting peak temperature calculated | required from the DSC curve measured according to JIS-K-7121 of the said PTT is 180 degreeC-240 degreeC. More preferably, it is 200 degreeC-235 degreeC. When the melting peak temperature is in the range of 180 to 240 ° C., the weather resistance is high, and the flexural modulus of the resulting composite fiber can be increased.

  The PTT contains various additives as necessary, for example, antistatic agents, pigments, matting agents, heat stabilizers, light stabilizers, flame retardants, antibacterial agents, lubricants, plasticizers, softeners, Antioxidants, ultraviolet absorbers, crystal nucleating agents, and the like can be mixed depending on the application and the like within a range not impairing the object and effect of the present invention.

  The composite ratio (core / sheath) is preferably 8/2 to 4/6 (volume ratio). More preferably, it is 7/3 to 45/55, and most preferably 6/4 to 5/5. The core component mainly contributes to the bulk recovery property, and 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 4/6, the strength and hardness of the nonwoven fabric and the bulk recoverability can be compatible. When the composite ratio becomes rich in the sheath, the strength of the nonwoven fabric increases, but the resulting nonwoven fabric tends to become harder and the bulk recovery also worsens. On the other hand, if the core becomes too rich, the number of adhesion points becomes too small and the strength of the nonwoven fabric becomes small, and this also tends to deteriorate the bulk recovery.

  In 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 composite fiber. FIG. 1 shows 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). Thereby, the surface of the first component (1) is melted at the time of thermal bonding. The centroid position (3) of the second component (2) is deviated from the centroid position (4) of the composite fiber (10), and the rate of deviation (hereinafter sometimes referred to as eccentricity) is that of the composite fiber. The cross section of the fiber is magnified with an electron microscope or the like, the center of gravity (3) of the second component (2) is C1, the center of gravity (4) of the composite fiber (10) is Cf, and the radius of the composite fiber (10) ( When 5) is rf, it is a numerical value represented by the following formula (Formula 2).

  The cross section of the fiber in which the center of gravity (3) of the second component (2) is deviated from the center of gravity (4) of the fiber is preferably an eccentric core-sheath type 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, the 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%. In addition to the circular shape, the shape of the second component in the fiber cross section may be elliptical, Y-shaped, X-shaped, well-shaped, polygonal, star-shaped, or the like, and in the fiber cross-section of the composite fiber (10). The form may be elliptical, Y-shaped, X-shaped, well-shaped, polygonal, star-shaped, or hollow, as well as circular.

  FIG. 2 shows the crimped form of the crimped conjugate fiber in one embodiment of the present invention. The corrugated crimp referred to in the present invention refers to a curved crest as shown in FIG. 2A. Spiral crimp refers to a crimped crest as shown in FIG. 2B. A crimp in which a wave shape crimp and a spiral crimp as shown in FIG. 2C are mixed is also included in the present invention. In the case of ordinary mechanical crimping as shown in FIG. 3, the initial bulk when the nonwoven fabric is formed cannot be increased if the so-called serrated crimp is a sharp crest. Furthermore, it is inferior to the surface elasticity against compression, the so-called spring effect, and in particular, sufficient initial bulk recovery is not obtained. Further, the present invention also includes a crimp in which the sharp crimp of the mechanical crimp as shown in FIG. 4 and the corrugated crimp shown in FIG. 2A are mixed.

  In the present invention, it is particularly preferable that the wave shape crimp and the spiral crimp shown in FIG. 2C are mixed in that both the card passing property and the initial bulk and bulk recovery properties can be achieved.

  Next, the manufacturing method of the crimped conjugate fiber of this invention is demonstrated. The crimped conjugate fiber can be produced as follows. First, as a first component containing 60 to 95% by mass of polybutene-1 and 5 to 40% by mass of polypropylene, and a second component that is a polymer having a melting point 20 ° C. higher than the melting point of polybutene-1, In the cross section, the first component occupies at least 20% of the fiber surface, and the second component uses a composite nozzle arranged such that the center of gravity of the second component deviates from the center of gravity of the fiber, such as an eccentric core-sheath composite nozzle. The components are melt-spun at a spinning temperature of 240 to 330 ° C. and the first component is spun at a spinning temperature of 200 to 300 ° C. and taken up at a take-up speed of 100 to 1500 m / min to obtain a spun filament. Next, the stretching process is performed at a stretching temperature of not less than the glass transition point of the second component and less than the melting point of the first component 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. This is because the fibers are fused when the stretching temperature is equal to or higher than the melting point of the first component. A more preferable lower limit of the draw ratio is 2 times. A more preferable upper limit of the draw ratio is 4 times. If the draw ratio is less than 1.8 times, the draw ratio is too low, so it is difficult to obtain a fiber in which corrugated crimps and / or spiral crimps are expressed, and not only the initial bulk is reduced, but also the fibers Since its own rigidity is also reduced, it tends to be inferior in non-woven fabric processability such as card passage property and in bulk recovery. Moreover, you may perform an annealing process in atmospheres, such as 90-115 degreeC dry heat, wet heat, and steam, before and after the said extending | stretching at this time as needed.

  Next, before or after applying the fiber treatment agent as necessary, a known crimping machine such as a stuffer box type crimping machine is used to perform crimping of 5 pieces / 25 mm or more and 25 pieces / 25 mm or less. 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 bulk and bulk recoverability of the nonwoven fabric tend to deteriorate. On the other hand, if 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 may be reduced. .

  Further, after the crimp is applied by the crimper, an annealing treatment may be performed in an atmosphere of dry heat, wet heat, or steam at 90 to 115 ° C. 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 115 ° C., thereby simplifying the process. This is preferable. When the annealing treatment is less than 90 ° C., the dry heat shrinkage tends to increase, and the formation of the resulting nonwoven fabric may be disturbed or the productivity may be lowered.

  The composite fiber obtained by the above method is mainly composed of at least one crimp selected from wave crimps and spiral crimps having a crimp number of 5/25 mm or more and 25/25 mm or less as shown in FIG. Therefore, a bulky nonwoven fabric can be obtained without deteriorating card processability described later, which is preferable. And it cut | disconnects to desired fiber length, and a crimpable conjugate fiber is obtained. A more preferable number of crimps is 10-20 pieces / 25 mm.

  Further, the crimped conjugate fiber of the present invention has at least one kind of crimp selected from corrugated crimps and spiral crimps. There is no. In the fiber state, the crimp may be completely manifested and manifested as a crimp, or may be a manifest crimp that leaves a slight occurrence of crimp (causes the appearance of crimp when the fiber is heated). May be. However, when crimps are developed so that the number of crimps exceeds 25/25 mm when heat is applied to the fibers (for example, when a temperature to be processed into a nonwoven fabric described later is applied), the initial bulk and bulk recovery properties are reduced. Therefore, it is not preferable.

  The dry heat shrinkage rate measured under the following conditions in accordance with JIS L 1015 in the crimped conjugate fiber of the present invention is preferably 5% or less. A more preferable dry heat shrinkage rate is 3% or less. When the dry heat shrinkage rate exceeds 5%, when the non-woven fabric is heat-treated, the non-woven fabric itself shrinks with the shrinkage, and the non-woven fabric processability and the non-woven fabric texture are deteriorated. Moreover, there is a possibility that crimps may be excessively developed with heat shrinkage, and the number of crimps is excessively increased, so that the initial volume and bulk recoverability of the nonwoven fabric tend to be deteriorated. Incidentally, the dry heat shrinkage of the crimped conjugate fiber of the present invention is determined according to JIS L 1015 by performing a dry heat treatment for 15 minutes at an initial load of 0.45 mN / dtex (50 mg / de) and a temperature of 120 ° C. It was measured.

  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 the 1st component adhere | attaches by heat processing. The fiber web may be subjected to needle punching treatment or hydroentanglement treatment as necessary before heat treatment. The heat treatment means is not particularly limited, but if the function of the crimped conjugate fiber of the present invention is sufficiently exhibited, a hot air penetration heat treatment machine, a hot air up-and-down heat treatment machine, an infrared heat treatment machine, etc. It is preferable to use a heat treatment machine that does not require much pressure. The heat treatment temperature may be set to a temperature range in which the crimped and / or helical crimps of the crimpable composite fiber have the following shape. For example, the melting peak temperature of PB-1 is Tm. It is preferable to set in the range of Tm-10 (° C) to the melting peak temperature of PP + 10 (° C). In particular, when at least PB-1 of the crimped conjugate fiber is melted and the constituent fibers are heat-sealed, an intersection of stronger fibers can be formed, and the bulk recoverability is increased, which is preferable. . Further, it is most preferable to perform heat fusion at a melting peak temperature of PP of ± 5 ° C.

  The nonwoven fabric preferably has an initial bulk recovery rate of 60% or more and a long-term bulk recovery rate of 85% or more obtained at 25 ° C. by the following measurement. A more preferable initial bulk recovery rate is 65% or more, and a long-term bulk recovery rate is 85% or more.

[Bulk recovery rate]
The required number of non-woven fabrics cut into 10 cm squares so that the total basis weight is about 1000 g / m ² is overlapped to measure the initial total thickness (To), and a 9.8 kPa load is applied at 10 cm squares on the overlapped non-woven fabrics. A weight was applied for 24 hours under an atmosphere of 25 ° C., the load was removed after 24 hours, and the total thickness (T ₁ ) of the laminated nonwoven fabric immediately after dewetting, and the total thickness (T ₂ ) after 24 hours dewetting. ) And the bulk recovery rate of the nonwoven fabric is calculated according to the following formulas, which are the initial bulk recovery rate and the long-term bulk recovery rate, respectively.

Initial bulk recovery rate (%) = (T ₁ / T ₀ ) × 100
Long-term bulk recovery rate (%) = (T ₂ / T ₀ ) × 100

  Non-woven fabric satisfying an initial bulk recovery rate of 60% or more and a long-term bulk recovery rate of 85% or more is an application in which pressure is repeatedly applied in the thickness direction, such as cushioning materials, interior materials for vehicles, pad materials such as brassieres, urethane, etc. It is suitable for applications that replace foam.

The non-woven fabric is a non-woven fabric entangled by a needle punch, and has a non-woven fabric hardness H ₀ (N) measured according to JIS-K-6401-5.4 (hardness test). When the hardness H ₁ (N) of the nonwoven fabric in the hardness test after the compression residual strain test measured according to 6401-5.5 (compression residual strain test) is used, the heating represented by the following formula The hardness retention is preferably 90% or more. A more preferable heating hardness retention is 100% or more, and even more preferably 105% or more. The heating hardness retention rate is an index indicating the degree of change in the hardness of the nonwoven fabric before and after being heated to 70 ° C., and the larger the value, the more the deterioration of the fiber or the nonwoven fabric itself due to heat is suppressed. Indicates.

Heat hardness retention rate (%) = (H ₁ / H ₀ ) × 100

The non-woven fabric is a non-woven fabric entangled by a needle punch, and has a non-woven fabric hardness H ₀ (N) measured according to JIS-K-6401-5.4 (hardness test). When the hardness H ₂ (N) of the nonwoven fabric in the hardness test after a repeated compression residual strain test measured according to 6401-5.6 (repeated compression residual strain test) is shown by the following formula: The durable hardness retention is preferably 90% or more. A more preferable durable hardness retention is 100% or more. The durable hardness retention is an index indicating the degree of change in the hardness of the nonwoven fabric before and after repeating 50% compression 80,000 times. The larger this value, the more the degradation of the fiber or nonwoven fabric itself due to compression is suppressed. Indicates that

Durability hardness retention (%) = (H ₂ / H ₀ ) × 100

  As the needle punched nonwoven fabric satisfying the heating hardness retention rate and / or the durable hardness retention rate, at least PB-1 of the crimped conjugate fiber is melted, preferably PB-1 and PP are melted. It can be obtained by bonding the fiber intersections.

Hereinafter, the present invention will be described more specifically with reference to examples.
(1) Polymer PTT ("CORTERRA9200" manufactured by Shell, melting peak temperature (mp) 228 ° C, IV value 0.92)
PET (“T200E” manufactured by Toray Industries Inc., mp 255 ° C., IV value 0.64)
PP-1 (Nippon Polypro "SA03E", mp 160 ° C, MFR 20, Q value 5.6)
PP-2 (“SA03B” manufactured by Nippon Polypro Co., Ltd., mp 160 ° C., MFR30, Q value 3.6)
PP-3 (Nippon Polypro "SA01A", mp160 ° C, MFR9, Q value 3.2)
PP-4 ("CJ700" manufactured by Prime Polymer Co., Ltd., mp160 ° C, MFR7, Q value 6.5)
PB-1a (“PB0400” manufactured by Sun Allomer, mp 123 ° C., MI20)
PB-1b (“DP0401M” manufactured by Sun Allomer, mp 123 ° C., MI15)
PBT elastomer ("Hytrel 4047H-36" manufactured by Toray DuPont, mp160 ° C)
HDPE (Nippon Polyethylene “HE481”, mp 130 ° C., MI12)
The blend ratio of the sheath component is listed in the table.

  In the above, IV is the intrinsic viscosity. MFR is a melt flow rate measured at 230 ° C. and 21.18 N (2.16 kgf) according to JIS K 7210. MI is a melt index of a polymer measured at 190 ° C. and 21.18 N (2.16 kgf) according to JIS K 7210.

  The Q value was measured under the following conditions.

I. Analytical device to be used (i) Cross sorter CFC T-100 (abbreviated as CFC) manufactured by Dia Instruments
(Ii) Fourier transform infrared absorption spectrum analysis FT-IR, Perkin Elmer 1760X
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)
The GPC column in the latter part of the CFC is used by connecting three AD806MS manufactured by Showa Denko KK 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 the following brands manufactured by Tosoh Corporation. F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000. A calibration curve is created by injecting 0.4 mL of a solution dissolved in ODCB (containing 0.5 mg / mL 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) When creating a calibration curve using standard polystyrene K = 0.000138, α = 0.70
(Ii) At the time of measuring a sample of polypropylene K = 0.00103, α = 0.78
In addition, although it measures by said GPC (gel permeation chromatography), when it measures by another model, it is Japan described in 2005 plastic molding material commerce manual (Chemical Industry Daily, published on August 30, 2004). It can be measured at the same time as “MG03B” manufactured by Polypro Co., Ltd., with the value when MG03B shows 3.5 as the blank condition, and the condition can be adjusted.
(2) Extrusion temperature: The core component polymer (PTT) was 280 ° C., the sheath component polymer was 250 ° C., and the nozzle cap temperature was 270 ° C.
(3) Number of nozzle holes: 600 holes (4) Composite ratio: Core / sheath = 55/45 (volume ratio)
(5) Unstretched fineness: 8 dtex
(6) Stretching temperature: wet 70 ° C
(7) Stretch ratio: 2.3 times (8) Crimp: 12-15 pieces / 25 mm
(9) Annealing temperature (drying temperature): 110 ° C. × 15 minutes (10) Product fineness × Fiber length: 4.4 dtex × 51 mm
(11) Nonwoven fabric manufacturing conditions

100% by mass of each crimpable conjugate fiber is put on a parallel card, and a web is collected. Using a hot air circulation type heat treatment machine, heat treatment is performed for 30 seconds at the processing temperature shown in Tables 1 to 3, and the sheath component is heat-sealed. A nonwoven fabric having a basis weight of about 100 g / m ² was obtained.

(12) Each measuring method [dry heat shrinkage] Measured according to JIS L 1015. The shrinkage is measured by dry heat treatment at an initial load of 0.45 mN / dtex (50 mg / de) and a temperature of 120 ° C. for 15 minutes.
[Area Shrinkage Ratio] The card web before thermal processing is cut into a length of 100 mm and a width of 100 mm, and the area reduction rate is measured when the card web is thermally processed at a predetermined temperature.
[25 ° C. bulk recovery rate] Prepare the required number of non-woven fabrics cut to 100 mm square so that the total basis weight is about 1000 g / m ² , superimpose them, and measure the initial thickness (To) under no load. Place the weight of 100 mm square and 9.8 kPa load on the laminated nonwoven fabric, apply the load at 25 ° C. for 24 hours, remove the load after 24 hours, and the thickness of the laminated nonwoven fabric immediately after dewetting (T ₁ ) , And the thickness (T ₂ ) after 24 hours of dewetting, and the bulk recovery rate of the nonwoven fabric is calculated by the following formula.

Initial bulk recovery rate (%) = (T ₁ / T ₀ ) × 100
Long-term bulk recovery rate (%) = (T ₂ / T ₀ ) × 100

All thickness measurements shall be under no load.
[70 ° C. Bulk Recovery] Same as above except that the temperature was 70 ° C. and the load was applied for 4 hours.
[Apparent density] Measured according to JIS K 6401 5.3 (apparent density test).
[Hardness] Measured according to JIS K 6401 5.4 (hardness test).
[Compressive residual strain] Measured according to JIS-K-6401-5.5 (Compressive residual strain test).
[Repetitive compressive residual strain] Measured according to JIS-K-6401-5.6 (repetitive compressive residual strain test).

[Examples 1-7, Comparative Examples 1-7]
Each condition and the obtained result are shown in Tables 1-3. In addition, about Example 2, 4, 6 and the comparative example 6, in order to match with the initial thickness of the comparative example 7, while adjusting the thickness with the net | network one sheet so that it may be 30 mm in thickness by overlapping 10 sheets Hot air processed.

  As is clear from the above results, Examples 1 to 7 of the present invention had the same basis weight and a larger initial thickness, and the initial bulk recovery rate and the long-term bulk recovery rate were higher than those of Comparative Examples 5 to 7. In Examples 3 to 7, corrugated crimps and spiral crimps are mixed, and compared with Examples 1 and 2, the single fiber dry heat shrinkage rate and the nonwoven fabric area shrinkage rate are low, and the initial thickness of the nonwoven fabric is low. It was thick and had high initial bulk recovery rate and long-term bulk recovery rate. This is presumably because polytrimethylene terephthalate was used as the second component (core component).

  On the other hand, in Comparative Examples 1-4, since polybutene-1 exceeded 95 mass%, the number of crimps exceeded 25 pieces / 25mm, and it was crimped clearly. As a result, the single fiber dry heat shrinkage ratio and the nonwoven fabric area shrinkage ratio were large, and the nonwoven fabric could not be produced stably. In Comparative Examples 1 to 4, since the polypropylene was less than 5% by mass, the resin viscosity at the time of melt spinning became too small to obtain a fiber having a uniform eccentric core-sheath cross section. Further, the maximum stretchable ratio was 2.7 times or less, and the stretchability was inferior.

  In Comparative Examples 5 to 6, although the initial thickness was higher than that of the Example, the initial bulk recovery rate was low.

  Since Comparative Example 7 uses a PBT elastomer for the sheath component, the expression of crimp is small, and the single fiber dry heat shrinkage rate and the nonwoven fabric area shrinkage rate are slightly larger than those of the Example, so that the nonwoven fabric is used. This was a nonwoven fabric with an initial thickness of only 30 mm and a low thickness.

[Examples 8 to 15]
Under the conditions described in Table 4, crimped conjugate fibers of Examples 8 to 11 were produced. Table 4 shows the obtained results. Further, 100% by mass of the crimped conjugate fiber obtained in Example 10 and Comparative Example 7 was put on a parallel card, and a cross lay web was produced using a cross layer. Next, needle punching was performed on the cross lay web using a cone blade manufactured by Foster Needle Co., Ltd. with a needle depth of 5 mm and the number of penets shown in Table 5 (both front and back). The obtained needle punched nonwoven fabric was heat-treated at a processing temperature shown in Table 5 for 30 seconds using a hot-air circulating heat treatment machine to heat-sheath the sheath component to obtain a nonwoven fabric. Table 5 shows the results of measuring the hardness, compression residual strain, heating hardness retention, repeated compression residual strain, and durable hardness retention of the obtained nonwoven fabric.

  As is clear from the results in Table 4, Examples 8 to 15 of the present invention all had the same basis weight and large initial thickness, and both the initial bulk recovery rate and the long-term bulk recovery rate were high. Among them, in Examples 12 and 13, since the Q value and MFR of PP added to the resin 2 were small, and the PP addition amount / Q value ratio was large, both the dry heat shrinkage rate and the nonwoven fabric area shrinkage rate of single fibers were extremely small. Met.

  As is clear from the results in Table 5, the needle punched nonwoven fabric of the present invention had a heat hardness retention rate and a durable hardness retention rate of 90% or more. It can be presumed that the bonding point between the fibers and the fibers themselves are not broken, bent, or the fiber strength is not lowered in both heat compression and repeated compression. On the other hand, the nonwoven fabric of Comparative Example 7 has a heat hardness retention rate as low as 84% and a durable hardness retention rate as low as 74%, and the nonwoven fabric hardness decreases due to compression when heated at 70 ° C. and repeated compression of 80000 times. It was inferior in heat resistance and durability.

FIG. 1 shows a fiber cross section of a crimped conjugate fiber according to an embodiment of the present invention. 2A to 2C show crimped forms of the crimped conjugate fiber in one embodiment of the present invention. FIG. 3 shows a form of conventional mechanical crimping. FIG. 4 shows the crimped form of the crimped conjugate fiber according to another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st component 2 2nd component 3 The gravity center position 4 of a 2nd component The gravity center position 5 of a composite fiber Radius 10 of a composite fiber Composite fiber

Claims (11)

A composite fiber comprising a first component and a second component,
The first component includes 60 to 95% by weight of polybutene-1 and 5 to 40% by weight of polypropylene,
The second component is a polymer having a melting point higher by 20 ° C. than the melting point of polybutene-1,
When viewed from 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 has at least one kind of crimp selected from wave-shaped crimps and spiral crimps.   The crimpable conjugate fiber according to claim 1, wherein the second component is polyester.   The crimpable conjugate fiber according to claim 2, wherein the polyester is polytrimethylene terephthalate.   The polybutene-1 has a melting peak temperature determined from a DSC curve measured according to JIS-K-7121 of 115 to 130 ° C., and a melt index (MI; measurement temperature 190 ° C., load) according to JIS-K-7210. The crimpable conjugate fiber according to any one of claims 1 to 3, wherein 2.16 kgf (21.18 N)) is in the range of 1 to 30 g / 10 minutes.   The crimped conjugate fiber according to any one of claims 1 to 4, wherein the polypropylene has a ratio (Q value) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 6 or less.   The polypropylene has a melt flow rate (MFR; measurement temperature 230 ° C, load 2.16 kgf (21.18 N)) according to JIS-K-7210 in the range of 5 to 30 g / 10 min. The crimpable conjugate fiber according to any one of the above.   A nonwoven fabric containing at least 30% by mass of the crimped conjugate fiber according to any one of claims 1 to 6.   The nonwoven fabric according to claim 7, wherein at least polybutene-1 of the crimped conjugate fiber is melted and the constituent fibers are heat-sealed. The nonwoven fabric according to claim 7 or 8, wherein the nonwoven fabric satisfies an initial bulk recovery rate of 60% or more and a long-term bulk recovery rate of 85% or more obtained at 25 ° C by the following measurement.
[Bulk recovery rate]
The required number of non-woven fabrics cut into 10 cm squares so that the total basis weight is about 1000 g / m ² is overlapped to measure the initial total thickness (To), and a 9.8 kPa load is applied at 10 cm squares on the overlapped non-woven fabrics. A weight was applied for 24 hours under an atmosphere of 25 ° C., the load was removed after 24 hours, and the total thickness (T ₁ ) of the laminated nonwoven fabric immediately after dewetting, and the total thickness (T ₂ ) after 24 hours dewetting. ) And the bulk recovery rate of the nonwoven fabric is calculated according to the following formulas, which are the initial bulk recovery rate and the long-term bulk recovery rate, respectively.
Initial bulk recovery rate (%) = (T ₁ / T ₀ ) × 100
Long-term bulk recovery rate (%) = (T ₂ / T ₀ ) × 100 The nonwoven fabric is a nonwoven fabric entangled by a needle punch,
The non-woven fabric hardness H ₀ (N) measured in accordance with JIS-K-6401-5.4 (hardness test),
When the hardness H ₁ (N) of the nonwoven fabric in the hardness test after the compression residual strain test measured according to JIS-K-6401-5.5 (compression residual strain test) is obtained,
The nonwoven fabric according to claim 7 or 8, wherein the heat hardness retention represented by the following formula is 90% or more.
Heat hardness retention rate (%) = (H ₁ / H ₀ ) × 100 The nonwoven fabric is a nonwoven fabric entangled by a needle punch,
The non-woven fabric hardness H ₀ (N) measured in accordance with JIS-K-6401-5.4 (hardness test),
When the hardness H ₂ (N) of the nonwoven fabric in the hardness test after a repeated compression residual strain test measured according to JIS-K-6401-5.6 (repeated compression residual strain test)
The nonwoven fabric according to claim 7 or 8, wherein a durable hardness retention represented by the following formula is 90% or more.
Durability hardness retention (%) = (H ₂ / H ₀ ) × 100

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