JP4783175B2 - Split composite short fiber and short fiber nonwoven fabric - Google Patents

Description

The present invention is a split type composite fiber composed of two components of a polyester polymer and a polyamide polymer, and after splitting, becomes a polyester short fiber and a polyamide short fiber, and the split ratio of both components is high, has excellent split resistance, Ru der relates splittable composite short fibers used in the dry nonwoven fabric by an air-laid method.

  In various fields including the sanitary materials field, short fibers made of thermoplastic resin such as polyester, polyamide, polyolefin, etc. are used and dispersed uniformly. Adhesion with binder resin, adhesion with hot air, pressure bonding with hot roll, high pressure Dry nonwoven fabrics and wet nonwoven fabrics obtained by water flow or entanglement with metal needles are used.

  Among them, there is a high demand for nonwoven fabrics that are excellent in soft texture, low air permeability, drapeability, wiping properties, etc., and in order to make such nonwoven fabrics, it has been proposed to use nonwoven fabrics made of ultrafine fibers. For example, Patent Document 1 proposes that a high-pressure liquid flow is jetted onto divided composite fibers deposited in a web shape to divide the fibers into a nonwoven fabric made of ultrafine fibers.

  Patent Document 2 and Patent Document 3 propose a nonwoven fabric made of ultrafine fibers obtained by obtaining a nonwoven fabric made of composite fibers and then dissolving one component of the composite fibers with a solvent.

  However, any nonwoven fabric has the disadvantages that the processing speed when dividing or eluting the composite fiber is slow, the processing method is complicated and expensive, and the composite fiber is not sufficiently divided or eluted. The quality of the nonwoven fabric was not satisfactory.

  Moreover, there exists an airlaid method as a method of obtaining a dry nonwoven fabric using a short fiber. The airlaid method employs a method in which fibers are defibrated and transported in a flow of air, passed through a screen having a wire mesh or pores, and then dropped and deposited on a wire mesh. In the conveying, dispersing, and laminating processes, the friction between the fibers and the fibers and the fibers and the metal is large, and static electricity is likely to be generated.

  When a fiber lump is formed, the passability in each process deteriorates and the operability is deteriorated. In addition, even in the obtained non-woven fabric, the accumulated fibers become non-uniform, resulting in a non-uniform non-woven fabric, and the product quality is remarkably lowered. .

  Today, many functional thermoplastic resins are used to differentiate products such as higher grades and higher functionality, including those that require low-temperature processing, thermoplastic resins with high tackiness, etc. Are used, and fibers having higher fiber-fiber friction and fiber-metal friction than conventional fibers are used. Further, in order to improve manufacturing processing efficiency, the processing speed is increased. Due to these factors, the amount of static electricity generated in the manufacturing process by the airlaid method is increased, and the generation of fiber mass is also increased.

The nonwoven fabric obtained by such an airlaid method is also required to be a nonwoven fabric composed of ultrafine fibers and having sufficient quality. However, when a fiber lump is generated due to the generation of static electricity, the splitting rate of the split-type composite fibers decreases, and therefore there is a problem that it is difficult to obtain a high-quality nonwoven fabric that is made of ultrafine fibers and has no spots. It was.
JP-A-62-133164 JP-A-62-78213 JP 56-154512 A

  The present invention solves the above-mentioned problems, and particularly in the production of dry nonwoven fabrics where fiber lumps are likely to occur due to the generation of static electricity, the split rate by air agitation is high, and by dividing easily into ultrafine fibers, A split type composite short fiber that is made of ultra fine fibers, has few undivided parts, is excellent in uniformity, has a soft texture, and can obtain a low air permeability nonwoven fabric, and an ultra fine split from this split type composite short fiber It is a technical problem to provide a short fiber nonwoven fabric containing fibers.

  The present inventors have reached the present invention as a result of intensive studies to solve the above problems.

That is, the gist of the present invention is the following (a) to (c) .
(A) A split type composite fiber composed of two components of a polyester-based polymer A and a polyamide-based polymer B, the fiber for obtaining a dry nonwoven fabric by the airlaid method, and with respect to the longitudinal direction of the fiber The cross-sectional shape of a single yarn cut perpendicularly has a shape in which a plurality of polyester polymers A are arranged in contact with the periphery of the polyamide-based polymer B (however, the composite fiber has a circular cross-sectional shape) excluding.), and the air agitation split ratio is 65% or more, the fiber length is 1.0～30Mm, single yarn fineness of Ri 0.5~20dtex der, the fibers, crimping has been granted, the single yarn wound The ratio (H / L) of the height (H) to the base (L) of the triangle connecting the two peak points of the valleys adjacent to the peak of the peak at the maximum peak of the crimped part is as follows. A split-type composite short fiber characterized by satisfying the formula (1) .
(1) Formula: 0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25
T is a decitex (dtex) number of single yarn fineness (b) A method for producing a short fiber nonwoven fabric, wherein a web is formed by the air laid method using the split type composite short fiber of (a ) above, and a nonwoven fabric is obtained. .
(C) A short fiber nonwoven fabric obtained by the method for producing a short fiber nonwoven fabric of (a).

The split type composite short fiber of the present invention has a high split ratio by air agitation, and is easily split into ultrafine fibers of polyester short fiber and polyamide short fiber, so that a dry mass by an airlaid method in which a fiber lump is likely to be generated particularly due to generation of static electricity. It can be suitably used in the production of nonwoven fabrics. And it becomes possible to obtain the nonwoven fabric which consists of an ultrafine fiber with few undivided parts, excellent uniformity, a soft texture, and low air permeability.

  In addition, since the short fiber nonwoven fabric of the present invention contains the ultrafine fibers of polyester short fibers and polyamide short fibers divided from the split type composite short fibers of the present invention, the uniformity and soft texture, low The nonwoven fabric has air permeability and can be used for various purposes.

  Hereinafter, the present invention will be described in detail.

The split type composite short fiber (hereinafter abbreviated as composite short fiber) of the present invention comprises two components, a polyester polymer (referred to as polymer A) and a polyamide polymer (referred to as polymer B). The cross-sectional shape of the single yarn cut perpendicularly to the longitudinal direction of each of the fibers has a shape in which a plurality of polymers A are arranged in contact with the periphery of the polymer B (however, the cross-sectional shape of the composite fiber is a circular cross-section) Except the ones.)

That is, as shown in FIGS. 1-3, around the polymer B, are those polymer A are plural arranged around, as shown in FIG. 1, the polymer A as the center of a polymer B Are arranged in contact with the periphery. The one shown in FIG. 2 is one in which eight polymers A are arranged in contact with the periphery around the polymer B, and the one shown in FIG. 3 is the polymer A around the polymer B. Twelve are arranged in contact with the periphery.

  The number of the polymers A arranged around the polymer B is preferably 2 to 20, and more preferably 3 to 8. The shapes of the polymers A and B are not particularly limited, and may be not only round or elliptical shapes but also polygonal shapes such as triangles and squares. These shapes may be appropriately selected in consideration of the shape and fineness of the fiber obtained after the division and the operability during spinning.

  Furthermore, the composite ratio of the polymer A and the polymer B may be appropriately adjusted in consideration of the use of a product such as a nonwoven fabric to be obtained, but the ratio of the polymer A may be 50% by mass or more. Among these, 75% by mass or more is preferable.

  Next, the composite short fiber of the present invention has a fiber length of 1.0 to 30 mm, and a more preferable fiber length is 2 to 25 mm, more preferably 5 to 15 mm. The single yarn fineness is 0.5 to 20 dtex, preferably 1.0 to 15 dtex. The fiber length was measured based on JIS L1015 8.4.1 (average fiber length) A method, and the single yarn fineness was measured according to JIS L1015 8.5.1 (positive fineness) B method (simple method). It is measured based on.

  When the fiber length is less than 1.0 mm, the fibers tend to be fused by heat generated when the fibers are cut. On the other hand, if it exceeds 30 mm, a fiber lump due to entanglement of fibers occurs during air agitation, and the fiber division rate decreases.

  If the single yarn fineness is less than 0.5 dtex, it is not preferable from the standpoints of operability and productivity during yarn production. On the other hand, if it exceeds 20 dtex, the fineness of the fibers after the division is not sufficiently reduced, and it becomes difficult to obtain ultrafine fibers.

  The composite short fiber of the present invention is obtained by melt-spinning from a spinneret in which dozens to thousands of spin holes having slit holes arranged so as to have the cross-sectional shape of a single yarn as described above are obtained. Further, since the yarn is manufactured as a yarn bundle (tow) of about 1 to 100 ktex, it is usually a suf-shaped one in which thousands to tens of thousands of single yarns are gathered.

  Furthermore, the composite short fiber of the present invention has an air stirring division ratio of 65% or more. The air agitation division ratio indicates a ratio at which the composite fiber is divided into a polyester short fiber made of the polymer A and a polyamide short fiber made of the polymer B when stirred in the air. That is, the air stirring division ratio in the present invention is measured and calculated as follows.

The composite short fiber of the present invention is used in a simple air flow agitation tester as shown in FIG. 7, and 100 g of the composite short fiber is introduced into the agitation tank 1 by air flow from the sample feeding blower 3 and 20 m from the agitation blower 2. The air flow of / sec is blown and stirred in the stirring tank 1 for 1 minute. The short fibers after stirring are taken out from the sampling port 4, and arbitrary 10 positions are selected, and an enlarged photograph of the fiber cross section is taken. The number of the polymer A (polyester short fiber) divided from the composite fiber is counted in the 10 photographs taken, and is calculated from the number of arrays of the polymer A before the division by the following formula. The average value of n number 10 is used.
Air stirring division ratio (%) = (number of divided polymers A / number of arrangements of polymers A before division) × 100
Example: In the schematic diagram of FIG. 5, the number of divided polymers A = 9, the number of arrays of the polymer A before dividing = 12, the dividing ratio (%) = (9/12) × 100 = 75

  When the air stirring division ratio is 65% or more, it is easily divided into ultrafine fibers of polyester short fibers and polyamide short fibers by air stirring, so of course when manufacturing dry nonwoven fabrics by airlaid method, wet nonwoven fabrics Even in the case of producing a non-divided portion, excellent uniformity, low air permeability, and soft texture nonwoven fabric can be obtained. If the air agitation division ratio is less than 65%, it is difficult to achieve the above effects. The air stirring division ratio is preferably 70% or more, and more preferably 75% or more.

  In addition, in the case of the composite short fiber in which the polymers A and B are arranged radially as shown in FIG. 4, division by air stirring becomes difficult, and the air stirring division ratio becomes low and cannot be made 65% or more.

Furthermore, the composite short fiber of the present invention is crimped . In particular, the ratio of the height (H) and the base (L) of the triangle connecting the top of the peak and two bottom points of the adjacent valley at the maximum peak of the crimped portion where the crimped form of the single yarn (H) / L) satisfies the following formula (1) .
(1) Formula: 0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25
T is the number of decitex (dtex) of single yarn fineness

  By adopting such a shape, the generation of static electricity is reduced, and the fact that short fibers gather to form a fiber mass is remarkably reduced, so that the air stirring division ratio is also high.

  That is, when the above crimped form is satisfied, the air stirring division ratio can be set to 70% or more, which is particularly suitable when a dry nonwoven fabric is obtained by the airlaid method. Furthermore, as will be described later, when the crimped form of the composite short fiber of the present invention satisfies all the expressions (1) to (3), the air stirring division ratio can be 75% or more.

  When a dry nonwoven fabric is obtained, particularly when it is produced by the airlaid method, static electricity is generated more. As an apparatus used for this airlaid method, for example, as disclosed in Japanese Patent Laid-Open No. 5-9813, a plurality of rotating cylinders are housed in a housing, and these cylinders are rotated at a high speed to positively move to the periphery of the cylinder. An apparatus that can generate an air flow and blow the fiber component in a predetermined direction by the air flow can be mentioned. In the web formation by the airlaid method (short fiber defibration, transport, dispersion, and lamination processes), the air flow is actively generated, so that the fibers are rubbed with each other. The generation of static electricity also increases due to friction with the (metal member).

  The composite short fiber of the present invention has a specific shape of the crimped fiber, so that in each step of web formation (defibration, transport, dispersion, lamination step), between fibers, between fibers and metal It is difficult to generate static electricity due to friction, and it is difficult to accumulate the generated static electricity, so that short fibers gather to form a fiber lump.

  When considering the problem of static electricity as described above, the more the number of crimps and the larger or stronger the crimps are applied, the easier it is to store electricity in terms of shape. That is, if the fiber is crimped, it exhibits a three-dimensional solid shape, so that static electricity tends to accumulate as the three-dimensional space portion increases. On the other hand, as the flat state without crimping becomes flat, it becomes more flat and less likely to accumulate static electricity. However, the number of contact points (surfaces) between fibers or between fibers and metal increases, and the generation of static electricity due to friction increases. .

  When considering the bulkiness, the bulkiness of the nonwoven fabric obtained decreases as the flat state without crimping decreases. On the other hand, the more the crimp is applied, the higher the bulkiness of the resulting nonwoven fabric, but the higher the bulkiness of the fibers. It tends to be a nonwoven fabric with poor uniformity.

  Moreover, the problem of static electricity and fiber entanglement, and the texture (bulkness and flexibility) of the resulting nonwoven fabric are also affected by the single yarn fineness. That is, in the problem of static electricity, static electricity is generated by contact between fibers or between a fiber and a metal, and thus the single yarn fineness factor that determines the size of the contact point and the contact surface is large. In addition, since a three-dimensional solid shape is formed by crimping, the single yarn fineness is a factor that determines the size of the space portion, and is a factor that determines the degree of static electricity and the degree of fiber entanglement.

  Therefore, the present inventors have considered these factors in consideration, and by making the shape of the split-type composite short fibers into a three-dimensional shape to which a specific crimp considering the single yarn fineness is given, (The prevention of static electricity and fiber entanglement and the improvement of the nonwoven fabric texture) were further improved, and further, the split-type composite short fibers were easily divided by air agitation, and the above-mentioned air agitation division ratio was further increased.

  First, as shown in FIG. 6, the fiber of the present invention is a single yarn crimped form in which the peak apex P of the peak portion at the maximum peak portion of the crimped portion and the bottom points Q and R of the adjacent valley portions are two. The points are connected to form a triangle, and the ratio (H / L) of the height (H) to the base (L) of the triangle satisfies the following formula (1).

Here, when there are a plurality of peak portions in the fiber length of the fiber of the present invention, the maximum peak portion means the one having the maximum peak height (H).
(1) Formula: 0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25

  In order to express the degree of crimp, the crimp rate is generally used, but the method for measuring the crimp rate is obtained from the difference in length between when a load is applied and when there is no load. However, in the present invention, even if the expression (3) that defines the crimping rate described later is satisfied, the crimping is such that the space part of the three-dimensional shape becomes large in some crimped parts in the fiber. If there is a part where the area is large, it is easy to accumulate static electricity, and the fibers tend to be entangled. Therefore, as specified in Equation (1), by specifying the shape at the maximum peak as a crimped shape, the size of the space portion due to crimping is specified, so that static electricity and fiber entanglement It is possible to prevent the generation of fiber lumps due to.

  When H / L is too large, the space portion becomes large in the three-dimensional shape of the fiber, and static electricity is easily accumulated, and the fiber becomes entangled easily. On the other hand, if the H / L is too small, the shape of the fiber becomes nearly flat, and the contact points (surfaces) between the fibers or between the fibers and the metal increase, so static electricity is likely to be generated, and a fiber lump is generated. The air stirring division ratio also decreases. For this reason, even if division processing such as air stirring is performed, the number of undivided portions increases, and the resulting nonwoven fabric tends to be poor in uniformity.

  In addition, the measurement of H / L is as follows. First, 1 g of short fibers are collected, and 20 single fibers are arbitrarily extracted therefrom. Then, an enlarged photograph (about 10 times) is taken with respect to the taken out single fiber, and as described above from the photograph, two points of the bottom points Q and R of the valley part adjacent to the peak part P at the peak part are adjacent to the maximum peak part. A triangle is formed, and the height (H) and the base (L) of the triangle are measured, and the ratio (H / L) is calculated. In this way, 20 single fibers are measured and the average value is taken.

  Next, the composite short fiber of the present invention preferably satisfies the formula (2): 0.1T + 3.8 ≦ crimped number ≦ 0.3T + 7.3 [T is the number of dtex of the single yarn fineness]. The number of crimps is measured and calculated based on JIS L1015 8.12.1. In addition, when the fiber length is short in the measurement of the number of crimps, it is measured on the fiber before cutting after the crimping and is converted into the number per 25 mm fiber length.

  If the number of crimps is higher than that in equation (2), the number of crimped parts that become a space part due to a three-dimensional solid shape will increase, and will be generated between fibers in the short fiber feeding, dispersion, and defibrating process by airflow This is not preferable because static electricity is easily accumulated and fibers are easily entangled with each other. On the other hand, when the value is lower than the expression (2), the crimped portion is reduced, so that the shape of the fiber is almost flat, and the number of contact points (surfaces) between the fibers or between the fiber and the metal increases, so that static electricity is easily generated. A ball-shaped fiber lump is formed, and the air stirring division ratio is lowered, which is not preferable. For this reason, even if it performs the division | segmentation process by air stirring etc., an undivided part increases and the nonwoven fabric obtained becomes a thing with poor uniformity.

  Furthermore, it is preferable that the composite short fiber of the present invention satisfies the following formula (3): 0.8T + 0.3 ≦ crimp rate ≦ 1.0T + 4.9 [T is the decitex (dtex) number of single yarn fineness]. This crimp rate is measured and calculated based on JIS L1015 8.12.2. In addition, when the fiber length is short in the measurement of the crimp rate, it is difficult to measure, and after the crimp is applied, the fiber is measured before being cut and converted to the number per 25 mm fiber length.

  When the crimping rate is higher than that of Equation (3), the space portion due to the three-dimensional solid shape increases or becomes large, and static electricity generated between the fibers in the process of feeding, dispersing, and defibrating short fibers in the air flow. Therefore, the fibers are easily entangled with each other, so that a ball-like fiber lump is generated and the air stirring division ratio is lowered, which is not preferable. On the other hand, when the value is lower than the expression (3), the shape of the fiber becomes almost flat, and the number of contact points (surfaces) between the fibers or between the fiber and the metal increases. This is not preferable because the air stirring division ratio is reduced. For this reason, even if it performs the division | segmentation process by air stirring etc., an undivided part increases and the nonwoven fabric obtained becomes a thing with poor uniformity.

  Next, the polymer A and the polymer B constituting the composite short fiber of the present invention will be described. When the composite short fiber of the present invention is used to obtain a nonwoven fabric, it is preferable to use both the polyester short fiber made of polymer A after splitting and the polyamide short fiber made of polymer B as main fibers.

  Therefore, the polymer A preferably has a melting point of 220 ° C. or higher, and more preferably has a melting point of 220 to 280 ° C. Specific examples include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Among these, PET is preferable. If necessary, a copolymerized polyester obtained by copolymerizing one or more of the following copolymerization components may be used.

  Copolymerization components include terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, bisphenol A, bisphenol S, cyclohexanedimethanol, 1,4-butanediol, 1,6-hexadiol, diethylene glycol, polyethylene glycol Etc.

One polymer B preferably has a melting point of 200 ° C. or higher, and more preferably has a melting point of 200 to 280 ° C. Specific examples include aliphatic polyamides and aromatic polyamides, among which nylon 6 and nylon 66 are preferable. If necessary, it may be a copolymerized polyamide in which other polyamides are copolymerized, or two or more kinds of polyamides may be mixed and used. Further, the effect of the composite short fiber of the present invention is not impaired. In ranges, matting agents such as titanium oxide, antioxidants such as hindered phenol compounds, ultraviolet absorbers, light stabilizers, pigments, flame retardants, antibacterial agents, conductivity-imparting agents, hydrophilic agents, water absorbing agents, etc. It may be blended.

The composite short fiber of the present invention, the dry nonwoven fabric applications, used for producing the d Areido method. According to the airlaid method, when the fiber is transported into the production machine (preliminary defibration or air sending) or defibrated, the fiber is easily divided into short polyester fiber and short polyamide fiber, and the process and equipment for dividing the fiber There is no need to provide it separately, which is advantageous in terms of cost.

  As described above, when the composite short fiber of the present invention is made into a nonwoven fabric, it is preferable that both the polyester short fiber made of polymer A and the polyamide short fiber made of polymer B after splitting are main fibers. Therefore, it is preferable to use other fibers having a low-melting-point polymer as a constituent component as a binder fiber and heat-treat to melt the low-melting-point polymer constituting the binder fiber to obtain a nonwoven fabric.

  By using a fiber having a low melting point polymer as a binder fiber, the binder fiber can be easily melted only by heat treatment with hot air, and a main fiber (polyester short fiber made of polymer A and polyamide short fiber made of polymer B) ) Can be adhered, so that a generally used bonding with a binder resin or a pressure bonding step with a hot roll can be omitted, which is advantageous in terms of cost.

  The shape of the other fibers used as the binder fiber is the same as that of the short fiber of the present invention in consideration of the uniformity, flexibility, etc. of the resulting nonwoven fabric. ) To (3) are preferred to satisfy the shape, number of crimps, and crimp rate.

Next, the short fiber nonwoven fabric of the present invention will be described. The short fiber nonwoven fabric of the present invention is a web obtained by producing the web by the airlaid method using the above-described composite short fiber, and the composite short fiber of the present invention is used in an amount of 40% by mass or more, especially 45% by mass. In addition, it is preferable to use 50 to 90% by mass.

  Then, the low-melting-point polymer of the binder fiber is melted by using other fibers that are divided from the composite short-fiber of the present invention, the main fibers are polyester short fibers and polyamide short fibers, and the low-melting-point polymer is a constituent component of the binder fiber. It is preferable that the main fibers are bonded together.

In the manufacture of staple fiber nonwoven fabric of the present invention, the ratio used of the composite staple fiber of the present invention is less than 40 wt%, the resulting nonwoven fabric, since the ratio of the ultrafine fibers is low, poor uniformity, Low air permeability and softness are also inferior. Also, it tends to have poor mechanical properties.

Moreover, if the ratio of the composite short fiber of the present invention used is 40% by mass or more, in addition to the binder fiber of the present invention, other short fibers serving as main fibers may be used together with the binder fiber as described above. Good.

  As described above, when using a binder fiber or a fiber other than the binder fiber, the shape of the single yarn is the same as that of the short fiber of the present invention in consideration of the uniformity and flexibility of the resulting nonwoven fabric. In addition, it is preferable that the shape, the number of crimps, and the crimp rate of the expressions (1) to (3) in the present invention are satisfied.

  Next, the manufacturing method of the composite short fiber of this invention is demonstrated using an example.

  Using a commonly used composite spinning device, a polyester polymer and a polyamide polymer are cross-sectionally contacted with the periphery of the polyamide polymer so that a plurality of polyester polymers are arranged. The composite spinning is performed from the spinning hole thus drilled. At this time, a spinneret in which several tens to several thousands of spinning holes are perforated is used, and the spun yarn is once wound without stretching. The obtained unstretched yarn is converged to make a tow of about 1 to 100 ktex, and subjected to heat stretching at a stretching ratio of 2 to 6 times and a temperature of about 20 to 90 ° C. And after providing crimp with a push-in type crimper, a finishing oil agent is provided if necessary, and it cuts into desired fiber length, and obtains the composite short fiber of this invention.

  In order for the crimped form of the single yarn to satisfy the crimped form specified in the present invention, the drawing conditions (magnification, temperature) and the crimping conditions (nip pressure) in a crimping apparatus such as a push-in crimper , Adjusting the stuffing pressure).

  Next, a method for producing the short fiber nonwoven fabric of the present invention (an example in which the composite short fiber of the present invention is used as a main fiber and another fiber as a binder fiber) will be described using an example.

  As a preliminary opening, a simple air flow agitation tester as shown in FIG. 7 is used to mix the composite short fiber and the binder fiber of the present invention at a predetermined mass ratio, and the agitation tank is supplied from the sample feeding blower 3 with an air flow. 1, an air flow of 20 m / second is blown from the stirring blower 2 and stirred in the stirring tank 1 for 1 minute. Subsequently, using the simple airlaid tester shown in FIG. 8, the composite short fiber and the binder fiber of the present invention that have been pre-opened are input from the sample input blower 13, and the disentanglement blade rotation motor 15 passes through the sprocket 16 for disentanglement blade rotation. Each set of five rotating first defibrating blades 11 and second defibrating blades 12 is defibrated and scattered and dropped. Thereby, the composite short fiber of this invention is divided | segmented into a polyester short fiber and a polyamide short fiber. Then, both the short fibers and the binder fibers that fall are sucked by the suction box 14 at the bottom, and deposited on the cotton collection conveyor 17 that moves in the direction of the arrow to produce a web. Subsequently, heat treatment (heat treatment temperature: melting point of binder fiber + about 10 ° C.) is performed by a heat treatment machine 18 located downstream, and the binder fiber is melted to obtain a dry nonwoven fabric mainly composed of polyamide short fibers and polyester short fibers. The basis weight adjustment of the nonwoven fabric is performed by changing the moving speed of the cotton collection conveyor 17.

Next, the present invention will be specifically described with reference to examples. In addition, the measuring method of each characteristic value in an Example is as follows.
(1) Melting point The temperature which gives the extreme value of the melting absorption curve measured with a differential scanning calorimeter (DSC7 manufactured by Perkin Elmer Co., Ltd.) at a temperature rising rate of 20 ° C./min was defined as the melting point.
(2) Relative viscosity (polyamide)
Measurement was performed at a concentration of 1 g / dl and a temperature of 25 ° C. using 96% sulfuric acid as a solvent.
(3) Intrinsic viscosity (polyester)
The measurement was carried out at a temperature of 20 ° C. using a mixture of equal mass of phenol and ethane tetrachloride as a solvent.
(4) Fineness, fiber length, H / L of crimped portion, number of crimps, crimp rate Measured and calculated by the above method.
(5) Air stirring division ratio Measured and calculated by the above method.
(6) Formation of fiber lump The obtained composite short fiber is air-stirred under the same conditions and method as the air-stirring division ratio. When taking out the short fibers after stirring, 0.1 g of the short fibers were collected and spread on black paper, and the presence or absence of a fiber lump was visually evaluated.
○: No fiber lump is generated Δ: A small amount of fiber lump is generated x: A large amount of fiber lump is generated (8) Uniformity, air permeability, and flexibility of the nonwoven fabric
The uniformity state of the obtained dry nonwoven fabric was observed visually, and was evaluated in three stages as follows.
○: Fully defibrated and uniform △: Partially undefibrated part ×: Insufficient defibration and non-uniformity-Air permeability-
The obtained dry nonwoven fabric was measured for air permeability using a fabric air permeability tester (AP-360 type, manufactured by Daiei Kagaku Seisaku Seisakusho), and was evaluated according to an average of 5 points as follows.
When fineness before division is 2.2 dtex ○: Air permeability is less than 20.0 cc / cm ² / sec.
Δ: The air permeability is 20.0 cc / cm ² / sec or more and less than 30.0 cc / cm ² / sec.
X: Air permeability is 30.0 cc / cm ² / sec or more.
When the fineness before division is 17.0 dtex ○: The air permeability is less than 30.0 cc / cm ² / sec.
Δ: The air permeability is 30.0 cc / cm ² / sec or more and less than 40.0 cc / cm ² / sec.
X: The air permeability is 40.0 cc / cm ² / sec or more.
-Flexibility-
The obtained dry nonwoven fabric was cut out into 20 cm × 20 cm as a sample, and the softness was evaluated by a three-stage evaluation as follows by the touch of the panel.
○: Good △: Somewhat bad ×: Bad

Reference example 1
As the core polymer, PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61 was used, and as the sheath polymer, PET obtained by copolymerizing 33 mol% of isophthalic acid having a flow start temperature of 130 ° C. and an intrinsic viscosity of 0.57 was used. Using a normal composite spinning apparatus, PET is the core, copolymer PET is the sheath component, the core-sheath mass ratio is 1/1, the spinning temperature is 280 ° C., the discharge rate is 446 g / min, and the spinning speed is 1170 m. Spinning was performed with a nozzle having a round cross section with 560 holes under the conditions of / min to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 12.3 ktex tow, then drawn at a draw ratio of 3.09 and a draw temperature of 60 ° C., and a crimping condition was applied by a push-in crimper with a nip pressure of 0.39 MPa and a stuffing pressure. Crimping was given as 0.07 MPa. Thereafter, an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil agent was applied so that the adhesion amount was 0.2% by mass, and then cut to obtain a short fiber having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm. It was.

Example 1
A PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61 is used as the polymer A, and a nylon 6 having a melting point of 216 ° C. and a relative viscosity of 2.53 is used as the polymer B. Melt spinning was carried out under the conditions of ° C., discharge rate of 568 g / min (PET 426 g / min, nylon 142 g / min) and spinning speed of 1000 m / min. At this time, composite spinning was carried out so that the cross-sectional shape of the single yarn was as shown in FIG. 1 (using a spinneret having 1014 spinning holes) to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 12.3 ktex tow and then drawn at a draw ratio of 2.55 times and a draw temperature of 70 ° C. Subsequently, crimping was applied with a push-in type crimper with the nip pressure of 0.38 MPa and the stuffing pressure of 0.10 MPa. Then, after applying an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil so as to have an adhesion amount of 0.2% by mass, it is cut into a composite short fiber having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm. Obtained.
Using the simple air flow agitating tester shown in FIG. 7, the obtained composite short fiber is a main fiber, the composite short fiber of Reference Example 1 is a binder fiber, and these are in a mass ratio of 80/20 (main fiber / binder fiber). After the cotton blending, the sample feeding blower 3 was introduced into the stirring tank 1 by an air flow, and an air flow of 20 m / second was blown from the stirring blower 2 and stirred (preliminary opening) in the stirring tank 1 for 1 minute.
Next, using a simple airlaid tester shown in FIG. 8, a dry nonwoven fabric having a basis weight of 100 g / m ² was obtained as follows. First, pre-opened composite short fibers and binder fibers are input from a sample input blower 13 and rotated by a defibrating blade rotating motor 15 via a defibrating blade rotating sprocket 16, respectively. The fiber was defibrated with the defibrating blade 12 and dropped. Thereby, the composite short fiber was divided | segmented into the polyester short fiber and the polyamide short fiber. Then, while dropping these short fibers and binder fibers with the suction box 14 at the bottom, they are deposited on the cotton collection conveyor 17 that moves in the direction of the arrow to create a web. Subsequently, heat treatment (heat treatment temperature: 140 ° C.) is performed in the heat treatment machine 18 on the downstream side, the binder fiber (sheath polymer constituting the binder fiber) is melted, and the polyester short fiber and the polyamide short fiber are used as main fibers. A dry nonwoven fabric was obtained. At this time, the basis weight adjustment of the nonwoven fabric was performed by changing the moving speed of the cotton collecting conveyor 17.

Example 2 and Comparative Example 1
Composite short fibers were obtained in the same manner as in Example 1 except that the spinneret was changed so that the cross-sectional shape of the single yarn was as shown in FIG. 2 and FIG. 4 as shown in Table 1.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 3-14
Various changes were made to the conditions (nip pressure, stuffing pressure) for applying crimp with the indentation type crimper as shown in Table 1, and the crimping form, number of crimps, and crimp rate shown in Table 1 were used. A composite short fiber was obtained in the same manner as in Example 1.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 15
A PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61 is used as a polymer A, and a nylon 66 having a melting point of 257 ° C. and a relative viscosity of 2.50 is used as a polymer B. Melt spinning was performed under the conditions of 290 ° C., discharge rate of 580 g / min (PET 435 g / min, nylon 145 g / min) and spinning speed of 1000 m / min. At this time, composite spinning was carried out so that the cross-sectional shape of the single yarn was as shown in FIG. 1 (using a spinneret having 1014 spinning holes) to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 12.8 ktex tow, and then drawn at a draw ratio of 2.60 times and a draw temperature of 70 ° C. Subsequently, crimping was applied using a push-in crimper with the crimping conditions set to a nip pressure of 0.40 MPa and a stuffing pressure of 0.12 MPa. Thereafter, an oil agent containing polyoxyethylene alkyl ether as a main component as a finishing oil agent was applied so that the amount of adhesion was 0.2% by mass, and then cut to form a composite short fiber having a single yarn fineness of 2.2 dtex and a fiber length of 5 mm. Got.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Comparative Example 2
A composite short fiber was obtained in the same manner as in Example 15 except that the spinneret was changed so that the cross-sectional shape of the single yarn became the shape shown in FIG.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 15.

Example 16
The same PET as in Example 1 is used as the polymer A, and the same nylon 6 as in Example 1 is used as the polymer B. These are used in a normal composite melt spinning apparatus, and the spinning temperature is 280 ° C., the discharge amount is 452 g / min (PET 339 g). / Min, 113 g / min of nylon), and melt spinning was carried out under conditions of a spinning speed of 900 m / min. At this time, composite spinning was performed (using a spinneret with 90 spinning holes) so that the cross-sectional shape of the single yarn was a fiber having a shape as shown in FIG. 1, and an undrawn yarn was obtained. The resulting undrawn yarn was focused on a 12.8 ktex tow and then drawn at a draw ratio of 3.28 times and a draw temperature of 75 ° C. Subsequently, crimping was applied using a push-in crimper with the crimping conditions set to a nip pressure of 0.48 MPa and a stuffing pressure of 0.17 MPa. Thereafter, an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil agent was applied so that the adhesion amount was 0.2% by mass, and then cut to obtain a composite short fiber having a single yarn fineness of 17 dtex and a fiber length of 5 mm. It was.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 17, Comparative Example 3
As shown in Table 1, composite short fibers were obtained in the same manner as in Example 16 except that the spinneret was changed so that the cross-sectional shape of the single yarn was as shown in FIG. 2 and FIG.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 16.

Examples 18-29
Various changes were made to the conditions (nip pressure, stuffing pressure) for applying crimp with the indentation type crimper as shown in Table 1, and the crimping form, number of crimps, and crimp rate shown in Table 1 were used. A composite short fiber was obtained in the same manner as in Example 16.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 16.

Example 30
The same PET as in Example 1 is used as the polymer A, and the same nylon 66 as in Example 15 is used as the polymer B. These are used in an ordinary composite melt spinning apparatus, and the spinning temperature is 290 ° C., the discharge rate is 464 g / min (PET 348 g). / Min, nylon 116 g / min), and melt spinning was performed under the conditions of a spinning speed of 900 m / min. At this time, composite spinning was performed so that the cross-sectional shape of the single yarn was as shown in FIG. 1 (using a spinneret with 90 spinning holes) to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 12.3 ktex tow and then drawn at a draw ratio of 3.37 and a draw temperature of 75 ° C. Subsequently, crimping was applied using a push-in crimper with crimping conditions of 0.52 MPa for nip pressure and 0.20 MPa for stuffing pressure. Thereafter, a commonly used spinning oil mainly composed of polyoxyethylene alkyl ether as a finishing oil was applied so that the adhesion amount was 0.2% by mass, and then cut to obtain a single yarn fineness of 17.0 dtex, a fiber length. A 5 mm composite short fiber was obtained.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Comparative Example 4
A composite short fiber was obtained in the same manner as in Example 30 except that the spinneret was changed so that the cross-sectional shape of the single yarn became the shape shown in FIG.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 30.

Examples 31-32, Comparative Examples 5-6
A composite short fiber was obtained in the same manner as in Example 1 except that the fiber length at the time of cutting was changed to the fiber length shown in Table 1, and a dry nonwoven fabric was obtained in the same manner as in Example 1.

Comparative Example 7
The same PET as in Example 1 was used as the polymer A, and the same nylon 6 as that used in the example 1 was used as the polymer B. These were used in a normal composite melt spinning apparatus, with a spinning temperature of 280 ° C. and a discharge rate of 244 g / min (PET 183 g). / Min, nylon 61 g / min), and melt spinning was performed under conditions of a spinning speed of 1200 m / min. At this time, composite spinning was performed so that the cross-sectional shape of the single yarn was as shown in FIG. 1 (using a spinneret with 2000 spinning holes), and an undrawn yarn was obtained. The resulting undrawn yarn was focused on a 12.2 ktex tow and then drawn at a draw ratio of 2.54 times and a draw temperature of 70 ° C. Subsequently, crimping was applied by a push-in type crimper with a nip pressure of 0.30 MPa and a stuffing pressure of 0.10 MPa. Then, after applying an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil so as to have an adhesion amount of 0.2% by mass, the composite short fiber having a single yarn fineness of 0.4 dtex and a fiber length of 5 mm is cut. Obtained.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Comparative Example 8
The same PET as in Example 1 is used as the polymer A, and the same nylon 6 as in Example 1 is used as the polymer B. These are used in a normal composite melt spinning apparatus, and the spinning temperature is 280 ° C., the discharge amount is 508 g / min (PET 381 g). / Min, nylon 127 g / min), and melt spinning was performed under conditions of a spinning speed of 600 m / min. At this time, composite spinning was performed so that the cross-sectional shape of the single yarn was as shown in FIG. 1 (using a spinneret with 90 spinning holes) to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 12.4 ktex tow and then drawn at a draw ratio of 4.28 times and a draw temperature of 75 ° C. Subsequently, crimping was applied using a push-in crimper with a crimping application condition of a nip pressure of 0.66 MPa and a stuffing pressure of 0.27 MPa. Thereafter, an oil agent mainly composed of polyoxyethylene alkyl ether as a finishing oil agent is applied so that the adhesion amount is 0.2% by mass, and then cut to obtain a composite short fiber having a single yarn fineness of 22 dtex and a fiber length of 5 mm. It was.
Next, using the obtained composite short fiber, a dry nonwoven fabric was obtained in the same manner as in Example 1.

  Table 1 shows measured values and evaluation results of the composite short fibers obtained in Examples 1 to 32, Comparative Examples 1 to 8, and Reference Example 1. Table 1 shows the evaluation results of the uniformity, air permeability, and flexibility of the dry nonwoven fabric using these composite short fibers.

  As is clear from Table 1, the composite short fibers of Examples 1 to 32 have a plurality of polymers A in contact with the periphery of the polymer B in the cross-sectional shape of the single yarn cut perpendicular to the longitudinal direction of the fibers. Individually arranged shapes were exhibited, and the air stirring division ratio was as good as 65% or more. Among these, the composite short fibers of Examples 1 to 8, 15 to 23, and 30 to 32 satisfy the formulas (1) to (3) in the crimped form (H / L, number of crimps, crimp ratio). Therefore, there was no generation of static electricity, no static electricity, and no fiber lump. And especially the air stirring division | segmentation rate was high and it was 75% or more, and it divided | segmented into an ultrafine fiber easily. For this reason, the dry nonwoven fabric containing these short fibers was excellent in uniformity, air permeability (low), and flexibility.

  On the other hand, since the composite short fibers of Comparative Examples 1 to 4 were those in which the polymers A and B were arranged radially in the cross-sectional shape of a single yarn cut perpendicularly to the longitudinal direction of the fibers, The rate was low. For this reason, the nonwoven fabric obtained from these short fibers has high air permeability and poor flexibility.

  Further, the composite short fiber of Comparative Example 5 was too short in fiber length, so that the fibers were adhered due to frictional heat at the time of fiber cutting, hardly opened by preliminary opening, and a nonwoven fabric could not be obtained. . Since the composite short fiber of Comparative Example 6 was too long, it was easy to accumulate static electricity, entangled fibers, formed a ball-shaped fiber lump, and had a low air stirring division rate. For this reason, the obtained dry nonwoven fabric was inferior in uniformity, high air permeability, and poor flexibility. The composite short fiber of Comparative Example 7 had a single yarn fineness that was too small, so that a cut yarn was generated during spinning and the spinning operability was poor. Further, the fibers were closely adhered by the cut yarn, and the air stirring division ratio was low. For this reason, the obtained dry nonwoven fabric was inferior in uniformity, high air permeability, and poor flexibility. Since the composite short fiber of Comparative Example 8 had a single yarn fineness that was too thick, the obtained dry nonwoven fabric had high air permeability and poor flexibility.

Examples 33 to 35, Comparative Example 9
The split composite short fiber of Example 1 is the main fiber, the short fiber of Reference Example 1 is the binder fiber, and the mass ratio (split composite short fiber of Example 1 / short fiber of Reference Example 1) is shown in Table 2. Various changes were made as shown, and both fibers were put into a simple air flow agitation tester shown in FIG. 7 to obtain a dry nonwoven fabric in the same manner as in Example 1.

Examples 36 to 38, Comparative Example 10
Table 2 shows split-type composite short fibers of Example 16 as main fibers, short fibers of Reference Example 1 as binder fibers, and their mass ratios (split-type composite short fibers of Example 16 / short fibers of Reference Example 1) are shown in Table 2. Various changes were made as shown, and both fibers were put into a simple air flow agitation tester shown in FIG. 7 to obtain a dry nonwoven fabric in the same manner as in Example 1.

  Table 2 shows the evaluation results of the uniformity, air permeability, and flexibility of the dry nonwoven fabrics obtained in Examples 33 to 38 and Comparative Examples 9 to 10.

  As is apparent from Table 2, the short fiber nonwoven fabrics (dry nonwoven fabrics) of Examples 33 to 38 contained 40% by mass or more of the composite short fibers of the present invention. It was excellent in properties.

  On the other hand, since the short fiber nonwoven fabrics of Comparative Examples 9 to 10 did not contain 40% by mass or more of the composite short fiber of the present invention, the air permeability was high and the flexibility was poor.

It is a cross-sectional view showing one embodiment of the cross-sectional shape of a single yarn cut perpendicularly to the longitudinal direction of the fiber of the split composite short fiber of the present invention. It is a cross-sectional view which shows the other embodiment of the cross-sectional shape of the single yarn cut | disconnected perpendicularly | vertically with respect to the longitudinal direction of the fiber of the split type | mold composite short fiber of this invention. It is a cross-sectional view which shows the other embodiment of the cross-sectional shape of the single yarn cut | disconnected perpendicularly | vertically with respect to the longitudinal direction of the fiber of the split type | mold composite short fiber of this invention. It is a cross-sectional view showing one embodiment of a split type composite short fiber in which the cross-sectional shape of a single yarn cut perpendicularly to the longitudinal direction of the fiber is a shape in which two types of polymers are arranged radially. It is a schematic diagram which shows the state which the division | segmentation type | mold composite staple fiber of FIG. 1 divided | segmented. It is an expansion explanatory view showing the crimp form of the single yarn of the split type composite short fiber of the present invention. It is explanatory drawing which shows the simple airflow stirring tester used when performing preliminary opening when measuring and calculating the air stirring division ratio of this invention. It is explanatory drawing which shows an example of the simple airlaid tester used when manufacturing the dry type nonwoven fabric by the airlaid method among the short fiber nonwoven fabrics of this invention.

Claims (5)

A split type composite fiber consisting of two components, a polyester polymer A and a polyamide polymer B, which is used to obtain a dry nonwoven fabric by the airlaid method and cut perpendicular to the longitudinal direction of the fiber In the cross-sectional shape of the single yarn, a shape in which a plurality of polyester polymers A are arranged in contact with the periphery of the polyamide-based polymer B is shown (however, the cross-sectional shape of the composite fiber is not circular. ), and the air agitation split ratio is 65% or more, the fiber length is 1.0～30Mm, single yarn fineness of Ri 0.5~20dtex der, the fibers, crimping has been granted, crimp form of single yarn At the maximum peak of the crimped part, the ratio (H / L) of the height (H) to the base (L) of the triangle connecting the top of the peak and the bottom of the adjacent valley is (1) A split type composite staple fiber characterized by satisfying the formula .
(1) Formula: 0.01T + 0.10 ≦ H / L ≦ 0.02T + 0.25
T is the number of decitex (dtex) of single yarn fineness Claim 1 Symbol placement of splittable composite short fiber crimps and crimp ratio satisfies the following (2) and (3) at the same time.
(2) Formula: 0.1T + 3.8 ≦ crimp number ≦ 0.3T + 7.3
(3) Formula: 0.8T + 0.3 ≦ crimp rate ≦ 1.0T + 4.9
However, the number of crimps is the number per 25 mm of fiber length, and T is the number of decitex (dtex) of single yarn fineness. A method for producing a short fiber nonwoven fabric, comprising using the split composite short fibers according to claim 1 or 2 to produce a web by an airlaid method to obtain a nonwoven fabric. 4. The method for producing a short fiber nonwoven fabric according to claim 3, wherein when the web is formed by the air laid method, the split type composite fiber is divided by an air flow in the air laid method. The short fiber nonwoven fabric obtained by the manufacturing method of the short fiber nonwoven fabric of Claim 3 or 4.