JP5045353B2 - Polyamide short fiber - Google Patents

Description

  The present invention relates to a short polyamide fiber having excellent permeability in a fiber production process and particularly excellent in wet nonwoven fabric processability.

  Conventionally, polyamide fibers have been widely known as general-purpose synthetic fibers, and short fibers are used in various fields such as apparel made of spun yarn and material use made of various non-woven fabrics.

  Polyamide short fiber has characteristics such as comparatively excellent strength and elongation characteristics, soft touch, unique texture, moderate hygroscopicity among general-purpose synthetic fibers, and wear resistance when used as a non-woven fabric. It is possible to obtain a structure excellent in physical durability such as property and chemical durability such as chemical resistance.

  Specifically, such nonwoven fabrics are used for battery separators, papermaking felts, abrasives, and the like.

  Conventionally, short fibers were often processed into non-woven fabrics by so-called dry manufacturing methods such as thermal bonding, but wet non-woven fabrics that are easy to obtain high densification while high performance such as densification of non-woven fabrics is required. Demand is growing.

  Since wet nonwoven fabrics and dry nonwoven fabrics have different processing methods, the specifications of the raw cotton must also correspond to them. The wet nonwoven fabric is obtained by dispersing short fibers in water and making paper. Thus, in the manufacture of a wet nonwoven fabric, there is a step of dispersing short fibers in a water bath, and the dispersibility of the short fibers here is required to be good.

  Polyamide is originally a hydrophilic material, but if used as it is, its dispersibility in a water bath is usually insufficient, and it is used after applying an oil agent (hereinafter referred to as a hydrophilic oil agent) that increases the hydrophilicity of the fiber. The

  However, the hydrophilic oil agent has adhesiveness and tends to have poor permeability in the fiber production process.

  When there are many yarn breaks in the fiber manufacturing process and winding trouble occurs on rollers and guides, if the end yarn part of the yarn break is included in the tow, it is cut into short fibers without applying tension. Therefore, a fiber length longer than the desired fiber length, that is, a fiber having an abnormal length may be generated.

  Therefore, in the fiber manufacturing process, the effect of increasing the hydrophilicity of the fiber is inferior, but an oil containing an oil such as mineral oil having excellent process passability is applied, and a hydrophilic oil bath is used in the subsequent fiber cutting process. A method of re-applying a hydrophilic oil agent is also used. The hydrophilic oil agent here is also called a dispersant.

  This method has the inconvenience that adding the oil agent is troublesome twice, the production efficiency is poor, and the process-passing oil agent previously applied is practically deoiled, resulting in a large drainage load.

  Therefore, there is a demand for an oil component that is consistently excellent in process passability from the fiber production process to the higher-order processing and can increase the hydrophilicity of the fiber.

Examples of making polyamide short fibers into wet nonwoven fabrics have been known so far, and Patent Documents 1 to 3 disclose a method for producing polyamide short fibers for use in wet nonwoven fabrics. Is disclosed that a long fiber bundle having a moisture content is cut by a rotary blade type fiber bundle cutting device. Patent Document 2 discloses that a polyamide component containing a bisamide compound is exposed on the fiber surface. However, it is only disclosed that the cross-sectional shape of the fiber is a multi-leaf shape, the oil agent to be used is not specifically shown, and an oil agent component that satisfies the above requirements has been found so far. There wasn't.
JP 2004-91970 A JP 2006-89886 A JP 2007-186813 A

  The present invention has been made in view of the background of the prior art, and an object of the present invention is to provide a short polyamide fiber that is excellent in passability in a fiber production process and suitable for use in a wet nonwoven fabric.

The present invention employs the following means in order to solve such problems.
That is, the anionic oil component having a linear hydrocarbon group having a carbon number is 10 to 14, becomes attached and a nonionic oil component having a linear hydrocarbon group having a carbon number is 10 to 14 , the total adhesion amount of the oil component is 0.2 to 0.8 wt% per fiber weight, and is wet-laid nonwoven fabric for polyamide short fibers fiber length and wherein the range der Rukoto of 2~10mm .

  According to the present invention, it is possible to obtain a polyamide short fiber having good yarn-making process passing properties and excellent wet nonwoven fabric processability.

  The inventors of the present invention have made extensive studies on polyamide short fibers that satisfy both the yarn processability and the wet nonwoven fabric processability, and have found that this problem can be solved at once by adding a specific oil component. It is a thing.

  If the polyamide used for the polyamide short fiber of this invention is a polyamide which can be formed in a fiber, it can be preferably used. Among them, polycapramide and polyhexamethylene adipamide having excellent versatility can be preferably used, but hexamethylene adipamide which has high heat resistance and can be suitably used for various materials can be particularly preferably used. In addition, nylon 12 and polyamide having a copolymer component can be suitably used within a range not impairing the effects of the present invention.

The polyamide short fiber of the present invention is not limited to a single component fiber, and may be a composite fiber having a core-sheath structure or a sea-island structure. For example, a core-sheath composite fiber having a melting point difference of 20 ° C. or higher due to a combination of polyhexamethylene adipamide and polycapramide that can be used as a heat bonding binder is also preferable.
The polyamide short fiber of the present invention comprises an anionic oil component having a linear hydrocarbon group having 10 to 14 carbon atoms and a nonionic oil component having a linear hydrocarbon group having 10 to 14 carbon atoms. It is necessary to be attached. The fiber to which the oil component is attached has excellent processability in fiber production, and also has excellent hydrophilicity, which is a performance required for dispersion in a water bath during wet nonwoven fabric processing.

  As a nonionic oil agent component having a linear hydrocarbon group having 10 to 14 carbon atoms, for example, polyethers or fatty acid esters having a linear hydrocarbon group having 10 to 14 carbon atoms may be used. it can. Examples of the linear hydrocarbon group include linear alkyl and linear alkenyl. In addition, such nonionic oil components include ethylene oxide, propylene oxide, butylene oxide, etc., and block copolymers, random copolymers, alternating copolymers, etc. composed of combinations of a plurality of monomer components. The molecular chain of the nonionic oil component may contain a functional group such as an alkyl group having a branched structure, a hydroxyl group, an amide group, or an amino group.

  In the case of a polyether having a linear hydrocarbon group having 10 to 14 carbon atoms, its weight average molecular weight is preferably in the range of 200 to 20000, more preferably in the range of 400 to 15000. preferable. If the weight average molecular weight is too small, the tackiness becomes too high, and the oil component tends to drop off in the fiber production process, and the trouble of winding with the roller in the process may occur frequently. If the molecular weight is too large, the dispersibility in water at the time of wet nonwoven fabric processing may deteriorate.

  Examples of the anionic oil agent component having a linear hydrocarbon group having 10 to 14 carbon atoms include alkali metal salts such as alkyl phosphates and sulfates having a linear hydrocarbon group having 10 to 14 carbon atoms. Can be used.

  As the alkali metal in the alkali metal salt, sodium or potassium can be preferably selected.

  In the oil agent component used in the present invention, it is necessary to have a linear hydrocarbon group having 10 to 14 carbon atoms. This is called process passability in the yarn making process and imparting hydrophilicity to the fiber. This is because it generally satisfies two contradictory properties. When an oil agent having a hydrocarbon group with a carbon number of less than 10 is used, it is excellent in the effect of imparting hydrophilicity to the fiber, and the dispersibility of short fibers in the wet nonwoven fabric manufacturing process is good, but the adhesive property of the oil agent is By being high, in the fiber manufacturing process, winding around the rollers and guides increases. On the contrary, when an oil agent having a linear hydrocarbon structure having 15 or more carbon atoms is used, the resulting fiber has excellent smoothness, and the friction coefficient between the fiber and the metal also decreases. However, the dispersibility of short fibers in water in the wet nonwoven fabric manufacturing process becomes insufficient, and in order to obtain dispersibility, it becomes necessary to newly add a hydrophilic oil component.

  Since both the anionic oil component and the nonionic oil component satisfy the condition of having a linear hydrocarbon group having 10 to 14 carbon atoms, the anionic oil component and the nonionic oil component are mixed and used. It is possible to select an optimum mixing ratio in accordance with the manufacturing method.

  For example, the weight ratio of the anionic oil component to the nonionic oil component is preferably in the range of 10/90 to 60/40. If the weight ratio of the anionic oil component is less than 10%, static electricity is generated in the fiber manufacturing process in low humidity seasons such as winter, and the dispersibility in water during wet nonwoven fabric processing deteriorates. May be. Further, if the weight ratio of the anionic oil component exceeds 60%, foaming may increase during dispersion in water, so that it may be necessary to reduce the stirring speed or to add an antifoaming agent.

  Moreover, the total adhesion amount of the oil component to the fiber, that is, the oil amount is too low in the fiber manufacturing process due to poor dispersion in the water bath during wet nonwoven fabric processing, and generation of abrasion and static electricity in the process. It is not preferable because the passability deteriorates, and if the oil content is too high, the oil agent will drop off in the yarn forming process, so that winding around the rollers tends to occur and the operability deteriorates, which is not preferable. A preferred range is in the range of 0.2 to 0.8% by weight, more preferably in the range of 0.4 to 0.6% by weight, based on the fiber weight.

  It is important that components that impair the hydrophilicity of the polyamide short fibers are not attached as much as possible. For example, a silicone-based component, a neutral oil component, and the like are generally used as an oil agent component of a normal polyamide short fiber, but in the present invention, they are not adhered as much as possible.

  The fiber length of the polyamide short fiber of the present invention is preferably in the range of 2 to 10 mm. If the fiber length is too small, fiber fusion tends to occur in the process of cutting the long fiber to obtain such short fibers, and poorly dispersed fibers in the water bath frequently occur when processing into a wet nonwoven fabric. become. Moreover, when this fiber length is too large, the entanglement between fibers will become strong and the dispersibility in a water bath will worsen when processing into a wet nonwoven fabric.

  The polyamide short fiber of the present invention is obtained by applying a dispersion obtained by dispersing the above-described oil component in water, a so-called oil agent, to a polyamide tow-shaped fiber, and drying it to obtain a desired, specifically the above-described fiber length. It can manufacture by cut | disconnecting so that it may become. The oil agent should be applied to the tow-shaped fiber before stretching in consideration of the passability in the fiber production process. However, as an oil agent application method, uniform application to the surface of each individual fiber or In consideration of the ease of controlling the amount of adhesion described above, it is preferable to employ a method in which a tow-shaped fiber is passed through an oil bath, impregnated, and then the excess is squeezed out by a nip roller.

  The physical properties of the polyamide short fibers thus obtained are not particularly limited as long as they do not deteriorate the yarn making process and the wet nonwoven fabric permeability, but, for example, the single fiber fineness is used when used as a wet nonwoven fabric. In order to make use of functions such as thinning and denseness, it is preferably 2 dtex or less, and the dry strength is the durability when passing in the yarn making process and the nonwoven fabric processing process, and when actually used as a product In view of durability, it is preferably 2 cN / dtex or more. However, if the dry strength exceeds 7 cN / dtex, the burden on the knife when cutting the fiber is significantly deteriorated, and the operability and product yield in the fiber cutting process may be deteriorated.

  The dry elongation of the polyamide short fiber of the present invention is preferably 30% or more in view of the passability in the yarn production process and the nonwoven fabric processing process, and 100 in view of the shape retention of the final product nonwoven fabric. % Or less is preferable.

  The fineness, dry strength, and dry elongation referred to here are determined based on JIS L 1015 (1999) (chemical fiber staple test method).

  The polyamide short fibers of the present invention are preferably not crimped. Such straight fibers are preferred. If crimps are imparted, dispersibility in the water bath during processing of the nonwoven fabric deteriorates due to entanglement between the fibers, which is not preferable.

  The wet nonwoven fabric obtained by using the polyamide short fiber of the present invention can be used not only for filters such as an air filter but also preferably for various uses such as use as a battery separator.

  Hereinafter, the present invention will be described more specifically with reference to examples. The measuring method of various physical properties is as follows.

  Single fiber fineness, dry strength, and dry elongation were measured according to JIS L 1015 (1999) (chemical fiber staple test method).

  The oil content was calculated by subtracting the weight of the polyamide monomer and oligomer determined by the Kjeldahl method from the ethanol extract using a Soxhlet tube.

Example 1
A nylon 66 chip containing 0.30% by weight of titanium oxide was melted at a temperature of 280 ° C. by a single-screw extruder, spun using a base having a hole number of 600 holes, and cooled by chimney. The undrawn yarn was obtained by taking it up at a speed of 1300 m / min and storing it in a can.

  The tow obtained by bundling 50 undrawn yarns is passed through an oil bath adjusted so that the concentration of oil A is 1.5% by weight in the drawing process, and excess oil is squeezed with a nip roller. After that, steam was applied and stretched 3.0 times to obtain a tow.

  The composition of the oil agent A is a blend of decyl (C12) phosphate sodium salt and a polyether having a C12 structure in the molecular chain in a weight ratio of 50:50.

  When 10 tons of tow was produced, the number of occurrences of the trouble of winding around the stretching roller was 2, and the process passability was good.

  The obtained tow was cut into a fiber length of 5 mm with an EC rotor to obtain short fibers. When the short fibers were put into a water bath with stirring, they showed good dispersibility and good wet nonwoven fabric processability. Table 1 shows the measurement results of the general physical properties of the fiber.

(Example 2)
Example 1 except that a nylon 66 tip containing 0.30% titanium oxide is used on the core side and a nylon 6 tip containing 0.30% titanium oxide is used on the sheath side and spinning as a core-sheath composite fiber. Short fibers were produced in the same way. Table 1 shows the measurement results of the general physical properties of the fiber.

(Comparative Example 1)
Short fibers were produced in the same manner as in Example 1 except that the oil A was changed to the oil B.

  Here, the oil agent B is a mixture of octyl (C8) phosphate potassium salt and a polyether containing a C8 structure in the molecular chain in a weight ratio of 50:50.

  When producing 10 tons of tow, winding around the stretching roller due to adhesion of the oil agent occurred 20 times, and the operability was poor.

  Dispersibility in a water bath was good when wet nonwoven fabric processing was performed after fiber cutting.

(Comparative Example 2)
Short fibers were produced in the same manner as in Example 1 except that the oil A was changed to the oil C.

  Here, the oil agent C is a mixture of cetyl (C16) phosphate potassium salt and a polyether containing a C16 structure in the molecular chain in a weight ratio of 50:50.

  When the obtained short fibers were put into a water bath with stirring, they were not uniform when dispersed in the water bath, and thus the resulting nonwoven fabric was wrinkled, and the texture was poor.

Claims (1)

And anionic oil component having a linear hydrocarbon group having a carbon number is 10 to 14, Ri name attached and a nonionic oil component having a linear hydrocarbon group having a carbon number is 10 to 14, the total adhesion amount of oil component is 0.2 to 0.8 wt% per fiber weight, and wet-laid nonwoven fabric for polyamide short fibers fiber length and wherein the range der Rukoto of 2 to 10 mm.