JP4485860B2 - Short fiber for nonwoven fabric and short fiber nonwoven fabric - Google Patents

Description

  The present invention is a short fiber used in a nonwoven fabric such as a dry nonwoven fabric or a wet nonwoven fabric, and in the nonwoven fabric manufacturing process, web formation such as air flow, feeding of a short fiber by a card machine, dispersion, defibration, lamination process, etc. The present invention relates to a short fiber for a nonwoven fabric provided with an appropriate crimped form in which no fiber lump is generated in the process, and a short fiber nonwoven fabric containing the short fiber.

  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 and wet nonwoven fabrics obtained by water flow or entanglement with metal needles are used.

  In the case of obtaining a dry nonwoven fabric using such short fibers, especially in the airlaid method, the fibers are defibrated and transported in a flow of air, passed through a screen having a wire mesh or pores, and then on a wire mesh. However, in the process of defibrating, transporting, dispersing, and laminating short fibers, the friction between fibers and fibers and fibers and metals is large, and static electricity is easily generated. The problem of being apt to occur.

  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 for product differentiation, upgrading, and high functionality. Some of them require low-temperature processing, high-viscosity thermoplastic resins, etc. As compared with the conventional fiber, a fiber having a greater fiber-fiber friction and fiber-metal friction is used. In addition, 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.

  In order to solve such problems, it is effective to apply a fiber treatment agent having antistatic properties and smoothness to the fiber surface. As finishing oil agents that impart smoothness and antistatic properties, fats mainly composed of waxes or fatty acids, and quaternary ammonium salts containing long-chain alkyl groups are widely used. However, although these fats can impart antistatic properties to some extent, they cannot impart sufficient smoothness.

  On the other hand, silicone finishing oils are known as fiber finishing oils having excellent smoothness. For example, fibers and fiber cords to which dimethylsiloxane emulsion polymer, amine-modified silicone and the like are added have been proposed (for example, patents). (See Reference 1.)

  However, both the dimethylsiloxane emulsion polymer and the amine-modified silicone have insufficient antistatic properties, and further, there is a problem that the hydrophilicity is inhibited and the fiber and the obtained product are yellowed. Moreover, these are not short fibers but long fibers (fiber cords), and cannot solve the problems caused by the generation of static electricity in the manufacturing process of the nonwoven fabric.

  Further, as a fiber imparted with smoothness, antistatic property and hydrophilicity, a highly smooth fiber imparted with a mixture of an alkyl phosphate salt and an amide group-containing polyoxyalkylene-modified silicone composition has been proposed. (For example, see Patent Document 2.)

However, since this fiber also has smoothness and antistatic properties by applying a special treatment agent, there is a problem that it is disadvantageous in terms of operability and cost. In addition, there are various needs for the obtained nonwoven fabric, and various treatments are performed for the purpose of imparting high functionality to the nonwoven fabric, so that the resulting nonwoven fabric may be discolored or colored by the treatment agent applied to the fibers. There were problems and quality was insufficient.
Japanese Patent Publication No. 48-1480 Japanese Patent Laid-Open No. 9-67772

  The present invention solves the above problems and generates static electricity due to friction between fibers and fibers or between fibers and machines, particularly in the production process of a dry nonwoven fabric, without applying a special treatment agent to the fiber surface. The short fiber for a nonwoven fabric and the short fiber nonwoven fabric containing the short fiber, which can prevent the generation of fiber mass due to the above, can obtain a nonwoven fabric excellent in uniformity, high quality and sufficient bulkiness It is a technical challenge to provide

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) and (b).
(A) In a composite fiber composed of a polyester A mainly composed of alkylene terephthalate units and having a melting point of 220 ° C. or higher and a polymer B having a flow initiation temperature or a melting point 30 ° C. lower than that of the polyester A, the fiber length is 1.0 to 30 mm, A short fiber with a crimp of 0.3 to 40 dtex, and the crimped form of the single yarn connects the bottom points of the valleys adjacent to the peak of the peak at the maximum peak of the crimped part. The ratio (H / L) of the height (H) and base (L) of the triangular triangle satisfies the following formula (1), and the number of crimps and the crimp ratio satisfy the following formulas (2) and (3) at the same time: A short fiber for nonwoven fabric, characterized by:
(1) Formula: 0.01T + 0.1 ≦ H / L ≦ 0.02T + 0.25
(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 a number per 25 mm fiber length. T is a short fiber nonwoven fabric characterized by containing the short fibers for nonwoven fabric described in the dtex number (b) (a) of the single yarn fineness .

  Since the short fiber for nonwoven fabric of the present invention satisfies a specific crimped form, it does not give a special treatment agent to the fiber surface, and is caused by generation of static electricity due to friction between fibers and fibers and between fibers and machines. It is possible to prevent the generation of fiber clumps, and furthermore, since it is possible to prevent the entanglement of the fibers between the fibers and the fibers, the uniformity is excellent, the quality is high, and the bulkiness is sufficient. It becomes possible to obtain a nonwoven fabric (a dry nonwoven fabric and a wet nonwoven fabric).

  Moreover, since the short fiber nonwoven fabric of the present invention comprises the short fiber for nonwoven fabric of the present invention, both the dry nonwoven fabric and the wet nonwoven fabric have excellent uniformity, high quality, and sufficient bulkiness. Therefore, it can be used for various purposes.

Hereinafter, the present invention will be described in detail.
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 in 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), since an air flow is actively generated, the fibers are rubbed with each other. The generation of static electricity also increases due to friction with the device (metal).

  The short fiber of the present invention generates static electricity by friction between fibers and between fiber and metal in all web forming processes (defibration, transport, dispersion, and lamination processes) by making the fiber structure specific. It is difficult to prevent static electricity generated and the short fibers gather to form a fiber lump.

  When considering the problem of static electricity as described above, there are many crimps. That is, if the fiber is crimped, it exhibits a three-dimensional structure, so that static electricity is more likely to accumulate as the three-dimensional space portion increases. On the other hand, as the flat state without crimping becomes flat, the structure becomes planar and it becomes difficult to accumulate static electricity, but the contact points (surfaces) between the fibers or between the fibers and the metal increase, 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. Further, since a three-dimensional structure is formed by crimping, the single yarn fineness is a factor that affects the size of the space portion, and is a factor that affects the degree of static electricity and the degree of fiber entanglement.

  Therefore, the present inventors considered these factors in consideration and made the above-mentioned effect (static electricity, fiber entanglement) particularly by adopting a three-dimensional shape to which specific crimps were given in consideration of the single yarn fineness. And the improvement of the texture of the nonwoven fabric was found to be improved.

First, the short fiber for nonwoven fabric of the present invention, as shown in FIG. 1, in the crimped form of a single yarn, the apex P of the peak in the maximum peak of the crimped part, and the bottom point Q of the adjacent valley, A triangle is formed by connecting two points R, and the ratio (H / L) of the height (H) to the base (L) of the triangle satisfies the following expression (1). In particular, when a dry nonwoven fabric is obtained by the air laid method, it is preferable that H / L is represented by the formula (4).
Here, when there are a plurality of peak portions in the fiber length of the short fiber of the present invention, the maximum peak portion means the one having the highest peak height (H).
(1) Formula: 0.01T + 0.1 ≦ H / L ≦ 0.02T + 0.25
(4) Formula: 0.01T + 0.1 ≦ H / L ≦ 0.02T + 0.2

  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. In the present invention, even if the expression (3) that defines the crimping rate described later is satisfied, if there is a part where the crimping is greatly applied to some of the crimped parts in the fiber, the space of the three-dimensional structure A part becomes large, it is easy to accumulate static electricity, and it becomes easy to produce the entanglement of fibers. Therefore, as specified in the formula (1), by making the form at the maximum peak part specific as the crimped form, it becomes possible to prevent the generation of fiber mass due to static electricity or fiber entanglement.

  When H / L is too large, the space portion of the three-dimensional structure becomes large, static electricity is easily accumulated, and fiber entanglement tends to occur. On the other hand, if H / L is too small, 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. It is not preferable. Moreover, the obtained nonwoven fabric tends to be poor in bulkiness.

  For the measurement of H / L, 1 g of short fibers are collected, and 20 single fibers are arbitrarily taken out 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 short fibers of the present invention, (2): 0.1 T + 3.8 ≦ crimps ≦ 0.3 T + 7.3 [T is decitex (dtex) number of single yarn fineness] you satisfied. The number of crimps is measured and calculated based on JIS L1015 8.12.1. In addition, when the fiber length is short and measurement is difficult in the measurement of the number of crimps, the measurement is performed on the fibers before the crimping and before the cut, and converted into the number per 25 mm fiber length.

  If the number of crimps is higher than the formula (2), the number of crimped portions that become space portions due to a three-dimensional structure increases, and the short fibers are fed, dispersed, defibrated, and laminated between the fibers in the air flow. The generated static electricity is easily accumulated, and the 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 likely to occur. This is not preferable because a fiber-like fiber lump is formed. Moreover, the obtained nonwoven fabric tends to be poor in bulkiness.

Further, non-woven fabric short fiber of the present invention, (3): 0.8 T + 0.3 ≦ crimp ≦ 1.0 T + 4.9 [T is decitex (dtex) number of single yarn fineness] you satisfied. This crimp rate is measured and calculated based on JISL1015 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 part due to the three-dimensional structure increases, and the static electricity generated between the fibers is reduced during the feeding, dispersion, defibration, and lamination processes of the short fibers in the air flow. Since it becomes easy and the fibers are easily entangled, a ball-shaped fiber lump is generated, 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. Is not preferable. Moreover, the obtained nonwoven fabric tends to be poor in bulkiness.

In terms of the number of crimps and the crimp rate, it is preferable that the crimp number satisfies the formula (5) and the crimp rate satisfies the formula (6), particularly when a dry nonwoven fabric is obtained by the airlaid method.
(5) Formula: 0.1T + 4.8 ≦ crimp number ≦ 0.2T + 6.6
(6) Formula: 0.8T + 1.2 ≦ crimp rate ≦ 1.0T + 2.8

  The short fiber of the present invention has a fiber length of 1.0 to 30 mm and a single yarn fineness of 0.3 to 40 dtex, and a more preferable fiber length is 2 to 25 mm, more preferably 5 to 15 mm. The single yarn fineness is preferably 0.5 to 33 dtex, more preferably 1.0 to 25 dtex. The fiber length was measured based on the JIS L1015 8.4.1A method, and the fineness was measured based on the JIS L1015 8.5.1B method.

  The short fiber of the present invention is a composite fiber comprising a polyester A mainly composed of alkylene terephthalate units having a melting point of 220 ° C. or higher and a polymer B having a flow initiation temperature or melting point 30 ° C. lower than that of the polyester A, and only the polymer B is heated. It is preferable to use a binder fiber that melts by the above. Thus, when the short fiber of the present invention is used as a binder fiber to form a nonwoven fabric, the polymer B is fused and becomes an adhesive component, but the polyester A does not melt and becomes a fiber portion constituting the nonwoven fabric. . And the nonwoven fabric obtained using the short fiber of this invention may consist only of the short fiber of this invention, or may be used with the other fiber used as a main fiber.

  Examples of the polyester A in the short fiber of the present invention include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and among them, PET is preferable. And as long as the effect of this invention is not impaired, it is good also as a copolyester containing the copolymerization component as needed. For example, the copolymer components include terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, bisphenol S, bisphenol A, cyclohexane dimethanol, 1,4-butanediol, 1, 6-hexanediol, diethylene glycol, polyethylene glycol and the like, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA) and itaconic acid as flame retardant components (IA) or the like can also be copolymerized, whereby polyester A can be made flame retardant.

  When the melting point of the polyester A is less than 220 ° C., it is difficult to stably produce the composite fiber, and it is not preferable because the thermal degradation easily occurs during the thermal bonding treatment.

  On the other hand, the polymer B has a flow starting temperature or melting point of 30 ° C. or more lower than that of the polyester A, and is a polyester mainly composed of polyolefin or alkylene terephthalate units, and a copolymer polyester containing a copolymer component in PET or PBT. Is mentioned.

  If the difference between the flow starting temperature or melting point of the polymer B and the melting point of the polyester A is less than 30 ° C., it is necessary to increase the heat treatment temperature in order to fuse the polymer B. As a result, the polyester A and the polymer B are easily decomposed. The difference between the flow start temperature or melting point of polymer B and the melting point of polyester A is preferably 30 ° C to 180 ° C. If it exceeds 180 ° C, the melt viscosity becomes too low during spinning, and fiber formation tends to be difficult.

  As the polymer B, polyethylene, polybutylene, or the like can be used as the polyolefin. As the copolyester, it is preferable to use PET or PBT containing various copolymer components, and among them, copolymerized PET obtained by copolymerizing isophthalic acid can lower the flow start temperature or the melting point. ,preferable.

  At this time, the copolymerization amount of isophthalic acid is preferably 10 to 50 mol% with respect to the total acid component. If the copolymerization amount is less than 10 mol%, it is difficult to lower the melting point. When it exceeds 50 mol%, the polymer becomes amorphous, and single yarn adhesion occurs at the time of spinning, which tends to deteriorate the yarn forming property.

  Furthermore, as the polymer B, the copolyester containing at least one component of 1,4-butanediol component, aliphatic lactone component and adipic acid component in PET can lower the melting point and has crystallinity. Therefore, it is preferable. That is, by having crystallinity, the heat resistance of the fiber is improved, heat treatment can be performed in the fiber production process, and it becomes easy to adjust the physical property value of the fiber according to the application.

  The aliphatic lactone component is preferably a lactone having 4 to 11 carbon atoms, and particularly preferred lactone is ε-caprolactone (ε-CL).

  First, when an aliphatic lactone component is contained, the copolymerization amount is preferably 20 mol% or less, more preferably 10 to 20 mol%, based on the total acid component. When the proportion of the aliphatic lactone component is small, the crystallinity is improved, but it is difficult to lower the melting point. On the other hand, if the content is more than 20 mol%, the crystallinity is lowered, and single yarn adhesion occurs at the time of spinning, resulting in poor yarn forming properties.

  Next, when the 1,4-butanediol component is copolymerized, it is preferably 40 to 60 mol% with respect to the total glycol component. When the copolymerization amount is less than 40 mol% or exceeds 60 mol%, it is difficult to lower the melting point.

  When the adipic acid component is copolymerized, the amount of copolymerization is preferably 20 mol% or less, more preferably 10 to 20 mol%, based on the total acid component. When the copolymerization amount of the adipic acid component is less than 10 mol%, the crystallinity is improved, but the melting point tends to be high. On the other hand, if the content is more than 20 mol%, the crystallinity is lowered, and single yarn adhesion occurs at the time of spinning, resulting in poor yarn forming properties.

  Further, as the polymer B, any one of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA) and itaconic acid (IA) as a flame retardant component can be used. Either one or both may be copolymerized, and this makes it possible to impart flame retardancy to the polymer B as an adhesive component.

  In consideration of imparting flame retardancy to the short fiber of the present invention, it is preferable to copolymerize the above flame retardant component also in the polyester A, and either one of the polyester A and the polymer B is as described above. It is preferable that a flame retardant component is copolymerized, and it is preferable that both polyester A and polymer B are copolymerized with the above flame retardant component.

  The copolymerization amount is preferably 5 to 20 mol% when either component is used alone or when both components are used in combination. If it is less than 5 mol%, it tends to be difficult to impart flame retardancy. On the other hand, when it exceeds 20 mol%, the spinning operability tends to deteriorate.

  In addition, in polyester A and polymer B, matting agents such as titanium oxide, antioxidants such as hindered phenol compounds, ultraviolet absorbers, light stabilizers, pigments, flame retardants, as long as the effect is not impaired. Further, an antibacterial agent, a conductivity imparting agent, a hydrophilic agent, a water absorbing agent, and the like may be blended.

  The short fiber composite fiber of the present invention includes a core-sheath type in which polyester A is arranged in the core and polymer B in the sheath, a side-by-side type in which polyester A and polymer B are bonded together, and polyester A is an island. It is preferable to use a sea-island type with the polymer B as the sea part. As a result, the proportion of the low-melting point polymer B on the fiber surface increases, and it can be easily fused by heat treatment. Among them, the core-sheath type is preferable from the viewpoint of yarn production, and the core / sheath (mass ratio) is set to 1/4 to 4/1 as the core-sheath ratio in consideration of the texture and spinning operability of the obtained nonwoven fabric. It is preferable to do.

  And the short fiber of this invention may have a hollow part as needed, and the one component may be eccentric.

  The short fibers for nonwoven fabric of the present invention are suitable as short fibers for dry nonwoven fabrics and wet nonwoven fabrics, and the dry nonwoven fabrics are particularly suitable as short fibers for nonwoven fabrics produced by the airlaid method. According to the airlaid method, it is possible to easily obtain a non-woven fabric only by bonding with hot air, and it is possible to omit a bonding process using a binder resin or a pressure bonding process using a hot roll, which is advantageous in terms of cost.

  Furthermore, the short fiber for nonwoven fabric of this invention can be used suitably also for manufacture of a wet nonwoven fabric. As described above, the short fiber of the present invention can prevent the generation of fiber mass due to the generation of static electricity due to the friction between fiber and fiber or between fiber and machine, particularly in the production process of dry nonwoven fabric. Even in wet nonwoven fabrics, the dispersion of single fibers is good, and since there are few contact points (surfaces) between single fibers, it is difficult for fibers to converge, so that it is possible to obtain a wet nonwoven fabric with excellent uniformity and sufficient bulkiness it can.

  In order to satisfy the crimped form defined in the present invention as described above, the short fibers of the present invention satisfy the stretching conditions (magnification, temperature) in the manufacturing process as described later, and crimps such as an indentation type crimper. This can be done by adjusting crimping conditions (nip pressure, stuffing pressure) in the crimping device to appropriate values.

  Next, the short fiber nonwoven fabric of the present invention will be described. The short fiber nonwoven fabric of the present invention comprises the short fiber for nonwoven fabric of the present invention as described above. By containing the short fiber of the present invention, the nonwoven fabric has a unique texture excellent in bulkiness. Among them, the short fiber of the present invention is preferably contained in an amount of 30% by mass or more, and if it is less than 30% by mass, the texture of the nonwoven fabric tends to be poor in bulkiness.

  In the nonwoven fabric of this invention, it is preferable to use the short fiber of this invention as a binder fiber, and in this case, a sheath part becomes an adhesive component, a core part becomes a residual component, and becomes a fiber which comprises a nonwoven fabric. Moreover, in the nonwoven fabric of this invention, it is good also as what consists only of the short fiber of this invention (100 mass% use). In this case, the short fiber of the present invention serves as both a binder fiber and a main fiber.

  Moreover, in the nonwoven fabric of this invention, when using the short fiber of this invention as a binder fiber and using another fiber as a main fiber, it is preferable to contain 30 mass% or more of the short fiber of this invention. At this time, it is preferable to contain 45 to 70% by mass of the short fiber of the present invention.

  By having the crimped shape as described above, the short fiber for nonwoven fabric of the present invention can prevent the fibers from being entangled in the nonwoven fabric production process, and can form a uniform and bulky web. And when the short fiber of the present invention is used as a binder fiber, the sheath portion of the short fiber of the present invention is melted to become an adhesive component, but at the web stage, the main fiber and the short fiber of the present invention Therefore, even if the sheath of the short fiber of the present invention is melted, only the nonwoven fabric composed of the main fiber and the core of the short fiber of the present invention or the core of the short fiber of the present invention is used. The nonwoven fabric made of is excellent in uniformity and bulkiness.

  The main fiber used in the nonwoven fabric of the present invention is the same as that of the short fiber of the present invention in terms of the shape of the single yarn in consideration of the texture of the obtained nonwoven fabric, such as uniformity and bulkiness. It is preferable to use a short fiber that satisfies the shapes, the number of crimps, and the crimp rate of formulas (1) to (3).

  As such a main fiber, a synthetic fiber made of a thermoplastic resin made of polyester, polyamide, or the like can be used. Among them, a polyester mainly composed of an alkylene terephthalate unit, and the melting point of the polyester is 220 to 280. C. is preferred. Specific examples include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Among these, PET is preferable. Further, these polyesters may be copolymer polyesters obtained by copolymerizing one or more of the following copolymer components as required.

  Examples of copolymer components include terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, bisphenol S, bisphenol A, cyclohexanedimethanol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, Examples include polyethylene glycol.

  The short fiber nonwoven fabric of the present invention may be either a dry nonwoven fabric or a wet nonwoven fabric as described above. Further, the basis weight and the like are not particularly limited.

  Next, the manufacturing method of the short fiber for nonwoven fabrics of this invention is demonstrated using an example. Polyester A and polymer B are melt-spun using a commonly used compound spinning apparatus, and are wound up without stretching. The obtained undrawn yarn is converged to form a tow of about 1 to 100 ktex, and hot drawn at a draw ratio of 2 to 6 times and a temperature of about 20 to 90 ° C. And after providing a crimp with an indentation type crimper, a finishing oil agent is provided as needed, and it cuts into desired fiber length, and obtains the short fiber of this invention.

  At this time, in order to satisfy the crimping form defined in the present invention, the stretching conditions (magnification, temperature) and the crimping conditions (nip pressure, stuffing pressure) in the crimping apparatus such as a push-in crimper are set. Adjust appropriately.

  Next, about the manufacturing method of the short fiber nonwoven fabric of this invention, each of a dry-type nonwoven fabric and a wet nonwoven fabric is demonstrated using an example. In addition, the example which used only the short fiber of this invention (100% use) is described for both a dry-type nonwoven fabric and a wet-type nonwoven fabric.

  First, in the case of a dry nonwoven fabric (airlaid method), the short fiber of the present invention is fed from the sample loading blower 13 using the simple airlaid testing machine shown in FIG. Each set of five rotating first defibrating blades 11 and second defibrating blades 12 is defibrated and scattered and dropped. Falling short fibers are sucked by the suction box 14 at the lower part and deposited on a cotton collecting conveyor 17 that moves in the direction of the arrow to create a web, which is then heat treated by a heat treatment machine 18 downstream (polymer B). To obtain a dry nonwoven fabric. The basis weight adjustment of the nonwoven fabric is performed by changing the moving speed of the cotton collection conveyor 17.

  Moreover, in the case of a wet nonwoven fabric, the short fiber of this invention is thrown into a pulp disaggregator and stirred. Thereafter, the obtained sample is transferred to a paper machine, and after adding a dispersion oil mainly composed of an alkyl phosphate metal salt, stirring is performed with an accompanying stirring blade to make a paper, thereby obtaining a wet nonwoven web. The paper-made wet nonwoven web is subjected to heat treatment with a hot air dryer (polymer B is melted) to obtain a wet nonwoven fabric.

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) Flow start temperature Using a flotester (Shimadzu Corporation CFT-500 type), a load of 100 kgf / cm ²
The temperature was increased from the initial temperature of 50 ° C. at a rate of 10 ° C./min under the condition of a nozzle diameter of 0.5 mm, and the temperature was determined as the temperature at which the polymer began to flow out of the die.
(2) 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 heating rate of 20 ° C./min was defined as the melting point.
(3) Intrinsic viscosity Measured at a temperature of 20 ° C. using an equal mass mixture 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) Formation of fiber masses The short fibers obtained were evaluated for the production of fiber masses using the simple air flow agitator of FIG. 100 g of short fibers are pre-defibrated by a cotton sacking machine, and then introduced into the stirring tank 1 by an air flow from the sample feeding blower 3, and an air flow of 20 m / second is blown from the stirring blower 2 to the inside of the stirring tank 1. For 1 minute. 0.1 g of the fiber after stirring was sampled from the sampling port 4 and spread on black paper, and the presence or absence of an independent fiber mass 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 (6) Uniformity and bulkiness of the nonwoven fabric <dry nonwoven fabric>
-Uniformity-
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 ×: Incomplete defibration and non-uniformity-Bulkiness-
The obtained dry nonwoven fabric was cut into 20 cm × 20 cm to make a sample, and 10 cm of the samples were stacked, and an acrylic plate (370 g) of 25 cm × 25 cm × 5 mm was placed thereon, and a 1 kg weight was placed on the acrylic plate. The height of the center of each of the four sides of the lower surface was measured, and the three-level evaluation was performed as follows based on the average value of the four points.
(1) When using only the obtained short fiber as a dry nonwoven fabric (Examples 1 to 39, Comparative Examples 1 to 14)
○: The height is 8.5 mm or more Δ: The height is 7.5 mm or more and less than 8.5 mm ×: The height is less than 7.5 mm
(2) When the obtained short fibers and other fibers are used to form a dry nonwoven fabric (Examples 63 to 77, Comparative Examples 27 to 29)
○: The height is 5.5 mm or more Δ: The height is 4.5 mm or more and less than 5.5 mm ×: The height is less than 4.5 mm <wet nonwoven fabric>
-Uniformity-
The uniformity state of the obtained wet nonwoven fabric was observed with the naked eye, and was evaluated in three stages as follows.
○: Sufficiently dispersed and uniform Δ: Partially poorly dispersed portion ×: Insufficient dispersion and non-uniformity-bulkyness-
The obtained wet non-woven fabric was cut into 20 cm × 20 cm and used as a sample. A 10 cm pile of the samples was placed on a 25 cm × 25 cm × 5 mm acrylic plate (370 g), and a 1 kg weight was placed on the acrylic plate. The height of the center of each of the four sides of the lower surface was measured, and the three-level evaluation was performed as follows based on the average value of the four points.
(1) When it is set as a wet nonwoven fabric only using the obtained short fiber (Examples 40-62, comparative examples 15-26)
○: The height is 7.5 mm or more. Δ: The height is 6.5 mm or more and less than 7.5 mm. X: The height is less than 6.5 mm.
(2) When the obtained short fibers and other fibers are used to form a wet nonwoven fabric (Examples 78 to 92, Comparative Examples 30 to 32)
○: The height is 5.0 mm or more. Δ: The height is 4.0 mm or more and less than 5.0 mm. X: The height is less than 4.0 mm.

Example 1
As polyester A, a PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61 was used, and as polymer B, a polyester obtained by copolymerizing 33 mol% of isophthalic acid having a flow starting temperature of 130 ° C. and an intrinsic viscosity of 0.57 was used. Using a composite spinning apparatus, polyester A as a core, polymer B as a sheath component, a core-sheath mass ratio of 1/1, a spinning temperature of 280 ° C., a discharge rate of 446 g / min, and a spinning speed of 1170 m / min Then, spinning was performed with a nozzle having a round cross section with 560 holes 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. The crimp form, the number of crimps, and the crimp rate are shown in Table 1. Thereafter, a commonly used spinning oil mainly composed of polyoxyethylene alkyl ether as a finishing oil was applied so as to have an adhesion amount of 0.2% by mass, and then cut to obtain a single yarn fineness of 2.2 dtex and a fiber length. 5 mm short fibers were obtained.
Using only the obtained short fibers, a dry nonwoven fabric having a basis weight of 50 g / m ² was obtained using the simple airlaid tester shown in FIG. First, the short fibers fed from the sample feeding blower 13 are defibrated and scattered by a set of five first defibrating blades 11 and second defibrating blades 12 which are rotated by a defibrating blade rotating motor 15 via a defibrating blade rotating sprocket 16. I dropped it. Falling short fibers are sucked by the suction box 14 at the lower part and deposited on a cotton collecting conveyor 17 that moves in the direction of the arrow to create a web, which is then heat treated by a heat treatment machine 18 downstream (polymer B). ) To obtain a dry nonwoven fabric. 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 2-7, Comparative Examples 1-4, 33 and 34
Various conditions (nip pressure, stuffing pressure) for applying crimping with an indentation type crimper are changed as shown in Tables 1 and 2, and the crimping forms, the number of crimps and the crimping rate shown in Tables 1 and 2 are used. A short fiber was obtained in the same manner as in Example 1 except that the dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 10
As a polymer B, a polyester (melting point 206 ° C., intrinsic viscosity 0.63) copolymerized with 20 mol% of isophthalic acid was used. The draw ratio and the conditions for applying crimp with a push-in crimper (nip pressure, stuffing pressure) are shown in Table 1. As shown in Table 1, various changes were made, and the same procedure as in Example 1 was performed except that the crimped form, the number of crimps, and the crimping rate shown in Table 1 were used, and short fibers were obtained. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 11
As the polymer B, polyester (copolymerization temperature: 95 ° C., intrinsic viscosity: 0.56) copolymerized with 40 mol% of isophthalic acid is used. Various changes were made as shown in Table 1, and the same procedure as in Example 1 was carried out except that the crimped form, the number of crimps, and the crimp rate shown in Table 1 were used, and short fibers were obtained. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 12-13
As polymer B, a polyester (melting point: 158 ° C., intrinsic viscosity: 0.73) copolymerized with 15 mol% of ε-CL and 55 mol% of 1,4-butanediol is used. (Nip pressure, stuffing pressure) were variously changed as shown in Table 1, and the same procedure as in Example 1 was carried out except that the crimped form, the number of crimps, and the crimping rate shown in Table 1 were used. Obtained. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 14-15
Polyethylene having a melting point of 132 ° C. is used as the polymer B, and the draw ratio and the conditions for imparting crimp with a push-in crimper (nip pressure, stuffing pressure) are variously changed as shown in Table 1, and the crimp forms shown in Table 1 In the same manner as in Example 1 except that the number of crimps and the crimp rate were changed, short fibers were obtained. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 16-17
As the polymer B, polyester obtained by copolymerizing 29 mol% of isophthalic acid, 4.25 mol% of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA), and 4.25 mol% of itaconic acid ( Using the flow start temperature of 132 ° C. and the intrinsic viscosity of 0.61), the draw ratio and the crimping condition (nip pressure, stuffing pressure) with an indentation type crimper were variously changed as shown in Table 1 and shown in Table 1. A short fiber was obtained in the same manner as in Example 1 except that the crimped shape, the number of crimps, and the crimp rate were changed. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 18-19
As polyester A, 4.25 mol% HCA and 4.25 mol% polyester copolymerized with itaconic acid (melting point: 230 ° C., intrinsic viscosity: 0.63) were used, and as polymer B, the same copolymer polyester as in Example 10 was used. The stretching ratio and the conditions (nip pressure, stuffing pressure) for imparting crimp with a push-in crimper are variously changed as shown in Table 1 to have the crimp form, number of crimps, and crimp rate shown in Table 1. Otherwise, the same procedure as in Example 1 was performed to obtain short fibers. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 20-21
Table 1 shows the conditions (nip pressure, stuffing pressure) for imparting crimp with a draw ratio and a push-in crimper using the same copolymer polyester as Example 18 as polyester A and the same copolymer polyester as Example 16 as polymer B. Various changes were made as shown, and the same procedure as in Example 1 was carried out except that the crimped form, the number of crimps, and the crimping rate shown in Table 1 were used to obtain short fibers. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 22
Using the same polyester A and polymer B as in Example 1, using a composite spinning apparatus, using polyester A as the core, polymer B as the sheath component, and a core-sheath mass ratio of 1/1, spinning temperature 280 Spinning was performed with a nozzle having a round cross section with 65 holes, under the conditions of ° C., discharge rate of 268 g / min, and spinning speed of 1100 m / min to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 14.3 ktex tow, then drawn at a draw ratio of 3.41 times and a draw temperature of 60 ° C., and a crimping condition was applied by a push-in crimper with a nip pressure of 0.44 MPa and a stuffing pressure. Crimping was given as 0.14 MPa. The crimp form, the number of crimps, and the crimp rate are shown in Table 1. Then, after applying a commonly used spinning oil mainly composed of polyoxyethylene alkyl ether as a finishing oil so as to have an adhesion amount of 0.2% by mass, it was cut to obtain a single yarn fineness of 11 dtex and a fiber length of 5 mm. Short fibers were obtained. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 23-27, Comparative Examples 5 to 8, 35 and 36
Various conditions (nip pressure, stuffing pressure) for applying crimping with an indentation type crimper are changed as shown in Tables 1 and 2, and the crimping forms, the number of crimps and the crimping rate shown in Tables 1 and 2 are used. A short fiber was obtained in the same manner as in Example 22 except that. A dry nonwoven fabric was obtained in the same manner as in Example 1 using only the obtained short fibers.

Example 30
The same polyester A and polymer B as in Example 1, polyester A as the core, polymer B as the sheath component and a compound spinning device, spinning temperature of 280 ° C., discharge rate of 428 g / min, spinning speed of 750 m / min Then, spinning was performed with a nozzle having a round cross section with 65 holes to obtain an undrawn yarn. The resulting undrawn yarn was focused on a 14.3 ktex tow, then drawn at a draw ratio of 3.99 times and a draw temperature of 60 ° C., and a crimping condition was applied by a push-in crimper with a nip pressure of 0.51 MPa and a stuffing pressure. Crimping was given as 0.19 MPa. The crimp form, the number of crimps, and the crimp rate are shown in Table 1. Then, after applying a commonly used spinning oil mainly composed of polyoxyethylene alkyl ether as a finishing oil so as to have an adhesion amount of 0.2% by mass, it was cut to obtain a single yarn fineness of 22 dtex and a fiber length of 5 mm. Short fibers were obtained. Further, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Example 31-35, Comparative Examples 9 to 12, 37 and 38
Various conditions (nip pressure, stuffing pressure) for applying crimping with an indentation type crimper are changed as shown in Tables 1 and 2, and the crimping forms, the number of crimps and the crimping rate shown in Tables 1 and 2 are used. Except that, short fibers were obtained in the same manner as in Example 30. A dry nonwoven fabric was obtained in the same manner as in Example 1 using only the obtained short fibers.

Examples 38-39, Comparative Examples 13-14
Short fibers were obtained in the same manner as in Example 1 except that the fiber length at the time of cutting was changed to the fiber lengths shown in Tables 1 and 2. A dry nonwoven fabric was obtained in the same manner as in Example 1 using only the obtained short fibers.

  Tables 1 and 2 show measured values and evaluation results of the short fibers obtained in Examples 1 to 39 and Comparative Examples 1 to 14. Tables 1 and 2 show the evaluation results of uniformity and bulkiness when a dry nonwoven fabric is prepared using these short fibers.

As apparent from Tables 1 and 2, since the short fibers of Examples 1 to 39 satisfied the formula (1), in particular, Examples 1 to 7, 10 to 27, 30 to 35, 38 to Since the 39 short fibers satisfied the expressions (1) to (3), they did not generate static electricity, accumulate static electricity, and did not generate fiber clumps. For this reason, the obtained dry nonwoven fabric was excellent in uniformity and bulkiness.
On the other hand, since the H / L ratio of the short fibers of Comparative Examples 1, 3, 5, 7, 9, and 11 is larger than the range of the formula (1), all of them easily accumulate static electricity, and the fibers are entangled. A ball-shaped fiber mass was formed. Therefore, the obtained dry nonwoven fabric was non-uniform and inferior in quality.

Moreover, since the H / L ratio of the short fibers of Comparative Examples 2, 4, 6, 8, 10, and 12 is smaller than the range of the formula (1), the contact points (surfaces) between the fibers and between the fibers and the machine. ), The generation of static electricity increased, and a ball-like fiber lump was formed. For this reason, the obtained dry nonwoven fabric was non-uniform, inferior in quality, and inferior in bulkiness. Moreover, since the short fiber of the comparative example 13 had too short fiber length, the close_contact | adherence of the fiber generate | occur | produced with the frictional heat at the time of fiber cutting, and the nonwoven fabric was not able to be obtained. Since the short fiber of Comparative Example 14 was too long, it was easy to accumulate static electricity, and also entangled with the fiber, resulting in a ball-like fiber lump. The resulting dry nonwoven fabric was non-uniform and inferior in quality. there were. Since the short fibers of Comparative Examples 33, 35, and 37 had a larger number of crimps than the range of the formula (2), the short fibers of Comparative Examples 34, 36, and 38 had a smaller number of crimps than the range of the formula (2). Therefore, in all cases, a small amount of fiber lump was generated, and the obtained dry nonwoven fabric had partially unopened portions and was inferior in uniformity.

Examples 40-46, Comparative Examples 15-18
Using only the short fibers of Examples 1 to 7 and Comparative Examples 1 to 4, respectively, wet nonwoven fabrics were prepared as follows.
The obtained short fiber was put into a pulp disintegrator (manufactured by Kumagai Riki Kogyo) and stirred at 3000 rpm for 1 minute. After that, the obtained sample was transferred to a paper machine (Kumagaya Riki Kogyo's square sheet machine), and after adding a dispersion oil mainly composed of an alkyl phosphate metal salt, stirring was performed with an accompanying stirring blade to make the paper. And it was set as the wet nonwoven fabric web. The paper-made 25 × 25 cm wet nonwoven web was subjected to heat treatment at a temperature of 140 ° C. for 10 minutes with a box-type hot air dryer to obtain a wet nonwoven fabric having a basis weight of 50 g / m ² .
Table 3 shows the evaluation results of uniformity and bulkiness of the obtained wet nonwoven fabric.

Examples 47-62, Comparative Examples 19-26
As shown in Table 3, wet nonwoven fabrics were prepared in the same manner as in Example 40 using only the short fibers obtained in Examples and Comparative Examples.
Table 3 shows the evaluation results of uniformity and bulkiness of the obtained wet nonwoven fabric.

As is apparent from Table 3, the short fibers constituting the nonwoven fabrics of Examples 40 to 62 satisfy the formulas (1) to (3), and therefore have good dispersibility in water and do not converge the fibers. there were. For this reason, the obtained wet nonwoven fabric was excellent in uniformity and sufficient in bulkiness.
On the other hand, since the short fibers constituting the nonwoven fabrics of Comparative Examples 15, 19, and 23 had an H / L ratio larger than the range of the formula (1), the number of crimps and the crimp rate were further expressed by the formulas (2) and (3). Since the H / L ratio of the short fibers constituting the nonwoven fabrics of Comparative Examples 17, 21, and 25 is larger than the range of the formula (1), the crimp rate is further larger than the range of the formula (3). Therefore, in all cases, dispersibility in water was poor, and large fibers were converged. Therefore, the obtained wet nonwoven fabric was non-uniform and inferior in quality. Moreover, since the short fiber which comprises the nonwoven fabric of Comparative Examples 16, 20, and 24 has a H / L ratio smaller than the range of Formula (1), the number of crimps and a crimp rate are (2), (3) Formula In addition, since the H / L ratio of the short fibers constituting the nonwoven fabrics of Comparative Examples 18, 22, and 26 is smaller than the range of the formula (1), the crimp rate is further smaller than the range of the formula (3). Because of the small size, the obtained wet nonwoven fabrics were not sufficiently bulky.

Examples 63-67
As shown in Table 4, the short fibers of Example 1 are used as the binder fibers, the short fibers of Reference Example 1 are used as the main fibers (other fibers), and the mass ratio of the main fibers to the binder fibers (main fibers / binder fibers) is shown in Table 4. A dry nonwoven fabric was obtained in the same manner as in Example 1 except that various changes were made.

Comparative Example 27
The short fiber of Comparative Example 1 was used as the binder fiber, the short fiber of Reference Example 1 was used as the main fiber (other fiber), and the mass ratio of the main fiber to the binder fiber (main fiber / binder fiber) was 50/50. Except that, a dry nonwoven fabric was obtained in the same manner as in Example 1.

Examples 68-72
As shown in Table 4, the short fibers of Example 22 are used as the binder fibers, the short fibers of Reference Example 2 are used as the main fibers (other fibers), and the mass ratio of the main fibers to the binder fibers (main fibers / binder fibers) is shown in Table 4. A dry nonwoven fabric was obtained in the same manner as in Example 22 except that various changes were made.

Comparative Example 28
The short fiber of Comparative Example 5 was used as the binder fiber, the short fiber of Reference Example 2 was used as the main fiber (other fiber), and the mass ratio of the main fiber to the binder fiber (main fiber / binder fiber) was 50/50. Except that, a dry nonwoven fabric was obtained in the same manner as in Example 22.

Examples 73-77
As shown in Table 4, the short fibers of Example 30 are used as the binder fibers, the short fibers of Reference Example 3 are used as the main fibers (other fibers), and the mass ratio of the main fibers to the binder fibers (main fibers / binder fibers) is shown in Table 4. A dry nonwoven fabric was obtained in the same manner as in Example 30 except that various changes were made.

Comparative Example 29
The short fiber of Comparative Example 9 was used as the binder fiber, the short fiber of Reference Example 3 was used as the main fiber (other fiber), and the mass ratio of the main fiber to the binder fiber (main fiber / binder fiber) was 50/50. Except that, a dry nonwoven fabric was obtained in the same manner as in Example 30.

Reference example 1
A round cross section with a hole number of 518 using PET with a melting point of 256 ° C. and an intrinsic viscosity of 0.61, using a normal melt spinning apparatus, spinning temperature of 285 ° C., discharge rate of 344 g / min, spinning speed of 950 m / min. The undrawn yarn was obtained. The resulting undrawn yarn was focused on a 12.3 ktex tow, then drawn at a draw ratio of 3.18 times and a draw temperature of 70 ° C., and applied as a finishing oil without applying crimp with a push-in crimper. A spinning oil mainly composed of ethylene alkyl ether was applied so as to give an adhesion amount of 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.

Reference example 2
A round cross section with 120 holes, using a PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61, using a normal melt spinning apparatus, spinning temperature of 285 ° C., discharge rate of 328 g / min, spinning speed of 600 / min. The undrawn yarn was obtained. The resulting undrawn yarn was focused on a 14.2 ktex tow, then drawn at a draw ratio of 4.14 times and a draw temperature of 75 ° C., and without applying crimp with a push-in crimper, polyoxy as a finishing oil. A spinning oil mainly composed of ethylene alkyl ether was applied so as to give an adhesion amount of 0.2% by mass, and then cut to obtain a short fiber having a single yarn fineness of 11 dtex and a fiber length of 5 mm.

Reference example 3
A round cross-section with a hole number of 40 using a PET having a melting point of 256 ° C. and an intrinsic viscosity of 0.61, using a normal melt spinning apparatus at a spinning temperature of 285 ° C., a discharge rate of 283 g / min, and a spinning speed of 900 m / min. The undrawn yarn was obtained. The resulting undrawn yarn was focused on a 14.0 ktex tow, then stretched at a draw ratio of 3.57 times and a draw temperature of 80 ° C., and without applying crimp with a push-in crimper, polyoxy as a finishing oil. A spinning oil mainly composed of ethylene alkyl ether was applied so as to give an adhesion amount of 0.2% by mass, and then cut to obtain a short fiber having a single yarn fineness of 22 dtex and a fiber length of 5 mm.

  Table 4 shows the evaluation results of the uniformity and bulkiness of the dry nonwoven fabrics obtained in Examples 63 to 77 and Comparative Examples 27 to 29.

As is clear from Table 4, the dry nonwoven fabrics of Examples 63 to 77 contained the short fibers of the present invention, and thus were excellent in uniformity and sufficient in bulk. Especially, the nonwoven fabric (Examples 63-66, 68-71, 73-76) which contains the short fiber of this invention 30 mass% or more was excellent in both uniformity and bulkiness.
On the other hand, in Comparative Examples 27, 28 and 29, the short fibers constituting the nonwoven fabric are not the short fibers of the present invention, the H / L ratio is larger than the range of the formula (1), and the number of crimps and the crimp rate are ( Since it was larger than the range of the formulas (2) and (3), the obtained dry nonwoven fabric was not sufficiently uniform.

Examples 78-82
As shown in Table 5, the short fibers of Example 1 are used as the binder fibers, the short fibers of Reference Example 1 are used as the main fibers (other fibers), and the mass ratio of the main fibers to the binder fibers (main fibers / binder fibers) is shown in Table 5. A wet nonwoven fabric was obtained in the same manner as in Example 40 except that various changes were made.

Comparative Example 30
The short fiber of Comparative Example 1 was used as the binder fiber, the short fiber of Reference Example 1 was used as the main fiber (other fiber), and the mass ratio of the main fiber to the binder fiber (main fiber / binder fiber) was 50/50. Except for this, a wet nonwoven fabric was obtained in the same manner as in Example 40.

Examples 83-87
As shown in Table 5, the short fibers of Example 22 are used as the binder fibers, the short fibers of Reference Example 2 are used as the main fibers (other fibers), and the mass ratio of the main fibers to the binder fibers (main fibers / binder fibers) is shown in Table 5. A wet nonwoven fabric was obtained in the same manner as in Example 47 except that various changes were made.

Comparative Example 31
The short fiber of Comparative Example 5 was used as the binder fiber, the short fiber of Reference Example 2 was used as the main fiber (other fiber), and the mass ratio of the main fiber to the binder fiber (main fiber / binder fiber) was 50/50. Except for this, a wet nonwoven fabric was obtained in the same manner as in Example 47.

Examples 88-92
As shown in Table 5, the short fibers of Example 30 are used as the binder fibers, the short fibers of Reference Example 3 are used as the main fibers (other fibers), and the mass ratio of the main fibers to the binder fibers (main fibers / binder fibers) is shown in Table 5. A wet nonwoven fabric was obtained in the same manner as in Example 53 except that various changes were made.

Comparative Example 32
The short fiber of Comparative Example 9 was used as the binder fiber, the short fiber of Reference Example 3 was used as the main fiber (other fiber), and the mass ratio of the main fiber to the binder fiber (main fiber / binder fiber) was 50/50. Except that, a wet nonwoven fabric was obtained in the same manner as in Example 53.

  Table 5 shows the evaluation results of the uniformity and bulkiness of the wet nonwoven fabrics obtained in Examples 78 to 92 and Comparative Examples 30 to 32.

As is apparent from Table 5, the wet nonwoven fabrics of Examples 78 to 92 were excellent in uniformity and sufficient in bulkiness because they contained the short fibers of the present invention. Especially, the nonwoven fabric (Examples 78-81, 83-86, 88-91) containing 30 mass% or more of the short fiber of this invention was excellent in both uniformity and bulkiness.
On the other hand, in Comparative Examples 30, 31, and 32, the short fibers constituting the nonwoven fabric are not the short fibers of the present invention, the H / L ratio is larger than the range of the formula (1), and the number of crimps and the crimp rate are ( Since it was larger than the range of the formulas (2) and (3), the obtained dry nonwoven fabric was not sufficiently uniform.

It is an expanded explanatory view which shows the crimped form of the short fiber for nonwoven fabrics of this invention. It is explanatory drawing which shows the simple airflow stirring test machine for evaluating the production | generation of the fiber lump in an Example. It is explanatory drawing which shows the simple airlaid tester which manufactured the dry-type nonwoven fabric in the Example.

Claims (7)

In a composite fiber composed of a polyester A mainly composed of an alkylene terephthalate unit and having a melting point of 220 ° C. or higher and a polymer B having a flow initiation temperature or a melting point of 30 ° C. lower than that of the polyester A, the fiber length is 1.0-30 mm and the single yarn fineness is 0.3-40 dtex. And a short fiber to which crimps are imparted, wherein the crimped form of the single yarn is a triangle formed by connecting the two peak points of the valleys adjacent to the peak of the peak at the maximum peak of the crimped part. The ratio of height (H) to base (L) (H / L) satisfies the following formula (1), and the number of crimps and the crimp rate satisfy the following formulas (2) and (3) at the same time. A feature of short fibers for nonwoven fabrics.
(1) Formula: 0.01T + 0.1 ≦ H / L ≦ 0.02T + 0.25
(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. T is the number of decitex (dtex) of single yarn fineness. The polyester A in the core section, the nonwoven fabric for the short fibers according to claim 1, wherein the polymer B is a core-sheath type composite fibers disposed in a sheath portion. Non-woven fabric short fibers according to claim 1-2 polymer B is polyethylene terephthalate obtained by copolymerizing isophthalic acid. Polymer B is a polyester having crystallinity, comprising a terephthalic acid component, an ethylene glycol component, and a copolymerized polyester containing at least one component of a 1,4-butanediol component, an aliphatic lactone component, and an adipic acid component. The short fiber for nonwoven fabric according to any one of claims 1 and 2 . The nonwoven fabric according to any one of claims 1 to 4, wherein 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and / or itaconic acid is copolymerized with at least one of polyester A and polymer B. Short fiber. A short fiber nonwoven fabric comprising the short fiber for nonwoven fabric according to any one of claims 1 to 5 . The short fiber nonwoven fabric according to claim 6, comprising 30% by mass or more of the short fiber for nonwoven fabric according to any one of claims 1 to 5 .